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Bay Area Hydrology Model 2013 User Manual

1. FS PondPad FS PondPad 1 NI TI A 100 200 i 100 200 200 100 200 Grid Scale ft Set Area 12206 186 sq ft Grid Scale ft Set Area 12220 013 sa ft Grid X pr m Slope lm 1 Grid 2 jie Slope iz 1 Grid com Grid lo Jt Bay Area Hydrology Model 2013 User Manual March 2014 The default side slope value is 3 3 1 The side slopes can be individually changed by right clicking on the specific side which changes the line color from black to red and then entering the individual side slope value in the slope text box The grid scale can be changed by entering a new value in the grid scale box The default value is 200 feet PondPad Controls and Numbers Clear Line Point Sq Ft Grid Scale Grid X Grid Y Area Slope The Clear button clears all of the lines on the grid The Line button allows the user to draw new lines with the mouse The Point button allows the user to move individual points to alter the pond shape and size Converts the computed pond area from square feet to acres and back Changes the length of a grid line Default grid scale is 200 feet Horizontal location of the mouse pointer on the grid 0 is the upper left corner Vertical location of the mouse pointer on the grid 0 is the upper left corner Top area of the pond either in square feet or acres Side slope of the selected line side of the pond
2. 150 APPENDIX A DEFAULT BAHM2013 HSPF PERVIOUS PARAMETER VALUES FOR ALAMEDA AND SAN MATEO COUNTIES eere eren ene 151 APPENDIX B DEFAULT BAHM2013 HSPF PERVIOUS PARAMETER VALUES FOR SANTA CLARA COUNTY a 171 APPENDIX C DEFAULT BAHM2013 HSPF IMPERVIOUS PARAMETER VALUES FOR ALAMEDA SANTA CLARA AND SAN MATEO COUNTIES 191 APPENDIX D ADDITIONAL GUIDANCE FOR USING 2013 195 Infiltration Reduction 195 Flow Duration Outlet Structures Practical Design Considerations 196 Drawdown Time and Considerations eeeeseeeeeeeee eene ener nennen eene neni 197 Additional Resources 198 APPENDIX E BIORETENTION MODELING METHODOLOGY 201 xii Bay Area Hydrology Model 2013 User Manual March 2014 INTRODUCTION TO BAHM2013 BAHM2013 is the Bay Area Hydrology Model Version 2013 BAHM2013 is based on the WWHM Western Washington Hydrology Model stormwater modeling platform WWHM was originally developed for the Washington State Department of Ecology More information about WWHM can be found at www clearcreeksolutions com More information can be found about the Washington State Department of Ecology s stormwater management program and manual at www ecy wa gov programs wq stormwater manual html This user manual and develo
3. To input columns of values beyond to the right of the Storage column click on Not Used title and select the appropriate option Use Manual when the discharge has been included in the external spreadsheet 69 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Ele Edit View Help Summary Report zmeuemUiew5sasusMuoos SSO Table 1 Mitigated Facility Name Flows To Precipitation Applied Evaporation Applied Facility Type SSD TABLE Manual Infiltration Load File Browse iv Stage Computed Add La SSD Table Outlet Structure outlet 0 Riser Height ft 0 Riser Diameter in ure Riser Type Flat Notch Type Commercial Toolbox Orifice Dia in Height in E e o ERA 4 16 24 2013 4 16 Use Outlet Structure to input riser and orifice dimensions 70 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 fe Nix Ele Edit View Help Summary Report Or SOBs 2G SSD Table 1 Mitigated Flows Precipitation Applied Evaporation Applied Facility Type SSD TABLE Manual Infiltration Load File Browse Stage Computed Add La Stage f 1 Commercial Toolbox Tide Gate Series Demand Determine Outlet With Tide Gate Move Elements f
4. JI m _ CI AGE Lu 6 24 2013 4i PM Intitial Stage ft The SSD Table is a stage storage discharge table externally produced by the user and is identical in format to the stage storage discharge tables generated internally by BAHM2013 for ponds vaults tanks and channels The easiest way to create a SSD Table outside of BAHM2013 is to use a spreadsheet with a separate column for stage surface area storage and discharge in that order Save the spreadsheet file as a space or comma delimited file A text file can also be created if more convenient The SSD Table must use the following units Stage feet Surface Area acres Storage acre feet Discharge cubic feet per second cfs A fifth column can be used to create a second discharge cfs This second discharge can be infiltration or a second surface discharge 67 Bay Area Hydrology Model 2013 User Manual March 2014 Certain rules apply to the SSD Table whether it is created inside or outside of BAHM2013 These rules are 1 Stage feet must start at zero and increase with each row The incremental increase does not have to be consistent Storage acre feet must start at zero and increase with each row Storage values should be physically based on the corresponding depth and surface area but BAHM2013 does not check externally generated storage values Discharge cfs must start at zero Discharge does not have t
5. Auto Pond Auto Vault and Auto Tank all work the same Each optimizing routine automatically creates a pond vault or tank size and designs the outlet structure to meet the flow duration criteria The user can either create a pond vault or tank from scratch or optimize an existing design The following information applies to all three optimizing routines Auto Pond Auto Vault and Auto Tank but for the purposes of simplifying the following documentation the term Auto Pond applies equally to Auto Vault and Auto Tank Auto Pond requires that the Pre project and Mitigated basins be defined prior to using Auto Pond Clicking on the Auto Pond button brings up the Auto Pond window and the associated Auto Pond controls Auto Pond controls Automatic Pond Adjuster The slider at the top of the Auto Pond window allows the user to decide how thoroughly the pond will be designed for efficiency The lowest setting 0 min at the left constructs an initial pond without checking the flow duration criteria The second setting to the right creates and sizes a pond to pass the flow duration criteria 115 Bay Area Hydrology Model 2013 User Manual March 2014 however the pond is not necessarily optimized The higher settings increase the amount of optimization The highest setting farthest left will size the most efficient smallest pond but will result in longer computational time Pond Depth Pond depth is the total depth of
6. Bay Area Hydrology Model 2013 User Manual March 2014 45 C D Urban Flat 0 596 46 C D Urban Moderate 5 10 47 C D Urban Steep 10 20 48 C D Urban Very Steep gt 20 153 Bay Area Hydrology Model 2013 User Manual March 2014 Table 2 BAHM2013 Alameda San Mateo HSPF Pervious Parameter Values Part I PERLND No LZSN INFILT LSUR SLSUR KVARY AGWRC 1 5 2 0 100 400 0 05 0 8 0 985 2 4 8 0 075 350 0 10 0 8 0 985 3 4 5 0 055 300 0 15 0 8 0 985 4 4 2 0 045 200 0 25 0 8 0 985 5 5 2 0 090 400 0 05 0 8 0 955 6 4 8 0 070 350 0 10 0 8 0 955 7 4 5 0 045 300 0 15 0 8 0 955 8 4 2 0 040 200 0 25 0 8 0 955 9 5 2 0 090 400 0 05 0 8 0 955 10 4 8 0 070 350 0 10 0 8 0 955 11 4 5 0 045 300 0 15 0 8 0 955 12 42 0 040 200 0 25 0 8 0 955 13 5 0 0 060 400 0 05 1 2 0 997 14 4 6 0 050 350 0 10 1 2 0 997 15 4 2 0 040 300 0 15 1 2 0 997 16 3 8 0 030 200 0 25 1 2 0 997 17 4 5 0 080 400 0 05 1 2 0 980 18 4 3 0 060 350 0 10 1 2 0 980 19 4 1 0 045 300 0 15 1 2 0 980 20 3 9 0 035 200 0 25 1 2 0 980 21 4 5 0 070 400 0 05 1 2 0 950 22 4 3 0 055 350 0 10 1 2 0 950 23 4 1 0 040 300 0 15 1 2 0 950 24 3 9 0 030 200 0 25 1 2 0 950 25 4 5 0 070 400 0 05 1 2 0 950 26 4 3 0 055 350 0 10 1 2 0 950 27 4 1 0 040 300 0 15 1 2 0 950 28 3 9 0 030 200 0 25 1 2 0 950 29 4 3 0 050 400 0 05 1 8 0 99
7. 186 Bay Area Hydrology Model 2013 User Manual March 2014 29 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 30 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 31 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 32 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 33 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 34 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 35 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 36 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 37 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 38 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 39 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 40 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 41 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 42 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 43 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 44 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 45 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 46 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 47 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 48 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 187 Bay Area Hydrology Model 2013 Us
8. SCENARIOS lfFacility Name Sand Filter 1 Outlet 1 Outlet 2 Outlet 3 Pre Project Downstream Connections g 0 laus ili Sand Fiter Quick Filter i Facility Dimension Diagram Basic Element UEM onn B Sand Filter Outlet Structure Data VI Riser Height ft 0 Riser Diameter in 0 ES RiserType Flat ES EXE 4 Notch Type Pro Elements Right Side Slope H V Schematic sand Filter 1 Mitigated Top Side Slope Hv Infiltration ES Orifice Diameter Height E A Hydraulic Conductivity inZhr 0 Number ft LID Toolbox ib Rer DER Filter material depth f Zac no ed UE mds ER Total Volume Filtrated ac ft 0 0 0 Filter Storage Volume at Riser Head ac ft 000 0 Total Volume Through Riser ac ft Commercial Toolbox Size Infiltration Basin Initial Stage ft Move Elements Target 0 4 4 Ega Save xy Load sy x Show Filter Table Open Tabe 6 24 2013 2 30PM The sand filter is a water quality facility It does not infiltrate runoff but is used to filter runoff through a medium and send it downstream It can also have one or more surface outlets represented by an outlet structure with a riser and multiple orifices The user must specify the facility dimensions bottom length and width effective depth and side slopes The hydraulic conductivity
9. Commercial Toolbox Move Elements Ei Save xy Load sy 1 ft Flows To Area in Basin Available Pervious Acres _ BUibanMod 5 10 0 Show Only Selected Available Impervious Acres feBexsFms B Urban Stee 10 207 T BUibenves Roads Mod 5 10 Roads Steep 10 202 Di Forest Frat g 17 Forest 0 Mires if Roads VerStee gt 202 v Roof Area v Driveways Flat 0 52 CD Forest Ver 20 M Shrub 0 T C D Shrub Mod 5 107 r E D Shrub SI 10 20 2 g Driveways Mod 5 10 Driveways S102072 Driveways Vew gt 202 O jv Sidewalks Fla 05 E D Shrub Very 20 0 177 Ci Grass Fats 0 Cid GrassMods 10 0 M Ci Grass stet020 0 T EA GrassVeyo20 0 M D w 510 B5 ge 05 vir 2 1 PerviousTotal Impervious Total Basin Total E se E Ae ces Deselect Zero I Sidewalks Mod 5 10 51020 SidewaksVepp20z Parking Flat 0 572 PakingModbiUg 1 ParkingSteep 10 20 o Parking Very 20 SelectBy m _ 64372013 1 58 With the mouse pointer pull the other end of the line down to the trapezoidal pond and click on the pond This will bring up the From Basin to Conveyance screen As with the Pre project scenario we want to only connect the surface flow and the
10. Part III PERLND No CEPSC UZSN NSUR INTFW IRC LZETP 1 see Table 8 0 50 0 35 1 00 0 80 see Table 9 2 see Table 8 0 40 0 35 0 95 0 50 see Table 9 3 see Table 8 0 30 0 35 0 90 0 45 see Table 9 4 see Table 8 0 25 0 35 0 80 0 40 see Table 9 5 see Table 8 0 45 0 30 0 95 0 70 see Table 9 6 see Table 8 0 35 0 30 0 90 0 45 see Table 9 7 see Table 8 0 25 0 30 0 80 0 40 see Table 9 8 see Table 8 0 20 0 30 0 60 0 35 see Table 9 9 see Table 8 0 40 0 25 0 95 0 70 see Table 9 10 see Table 8 0 35 0 25 0 90 0 45 see Table 9 11 see Table 8 0 28 0 25 0 80 0 40 see Table 9 12 see Table 8 0 25 0 25 0 60 0 35 see Table 9 13 see Table 8 0 40 0 25 0 90 0 40 see Table 9 14 see Table 8 0 35 0 25 0 80 0 35 see Table 9 15 see Table 8 0 28 0 25 0 70 0 30 see Table 9 16 see Table 8 0 25 0 25 0 60 0 30 see Table 9 17 see Table 8 0 50 0 35 1 00 0 80 see Table 9 18 see Table 8 0 40 0 35 0 95 0 50 see Table 9 19 see Table 8 0 30 0 35 0 90 0 45 see Table 9 20 see Table 8 0 25 0 35 0 80 0 40 see Table 9 21 see Table 8 0 45 0 30 0 95 0 70 see Table 9 22 see Table 8 0 35 0 30 0 90 0 45 see Table 9 23 see Table 8 0 25 0 30 0 80 0 40 see Table 9 24 see Table 8 0 20 0 30 0 60 0 35 see Table 9 25 see Table 8 0 40 0 25 0 95 0 70 see Table 9 26 see Table 8 0 35 0 25 0 90 0 45 see Table 9 27 see Table 8 0 28 0 25 0 80 0 40 see Table 9 28 see Tabl
11. The user is required to enter the following information about the bioretention facility 78 Bay Area Hydrology Model 2013 User Manual March 2014 The bioretention dimensions are specified in terms of bottom length bottom width freeboard over road flooding effective total depth bottom slope and side slopes Bottom Length ft length dimension of surface bottom Bottom Width ft width dimension of surface bottom Freeboard ft height above riser to top of facility Over road Flooding ft maximum depth of flow over weir street only required for vertical orifice plus overflow outlet Effective Total Depth ft the total depth of the engineered soil layer s plus riser height plus freeboard effective total depth is computed by BAHM2013 Bottom Slope ft ft the slope of the bioretention facility length must be greater than Zero Top and Bottom Side Slope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical sides Top and bottom refer to sides on plan view of bioretention Left Side Slope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical sides Left refers to left side on plan view of bioretention Right Side Slope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical sides Right refers to right side on plan view of bioretention Infiltration Rate inches per hour infiltration rate of the engineered soil for all layers Layer Depth fee
12. vel TN 6 29 2013 4 47 PM The water balance chart graphically displays the runoff distribution for all three land use scenarios side by side The bottom red is the surface runoff Above in yellow is interflow then green for groundwater and blue for evaporation Basin 1 Scenario 1 is all shrub vegetation and produces the least amount of surface runoff and interflow the sum of surface and interflow is the total stormwater runoff Basin 2 is all urban vegetation it produces more surface runoff and interflow than Basin 1 Basin 3 is 50 urban vegetation and 5096 impervious and produces the largest amount of surface runoff and interflow and smaller amounts of groundwater and evaporation A maximum of seven scenarios can be graphed at one time 145 Bay Area Hydrology Model 2013 User Manual March 2014 This page has been intentionally left blank 146 Bay Area Hydrology Model 2013 User Manual March 2014 OPTIONS BAHM2013 Edit View Help Summary Report MELEE ITIS i FREE Subbasin Name Designate as Bypass for POC Interflow Groundwater Show Only Selected Available Impervious Acres Roads Flat 0 5 r Rasm p Pointof Compliance Based on Predeveloped Flow Frequency 00000 T ReadsSteep ID20 1 Analyze Durations to 10 percent of the 2 x Roads VerStee gt 20 0 tothe yr i Roof Area D Driveways Flat 0 52 Durations Based on User Defined F
13. Load x Savery toads AN _ gt ajas 672372013 4 32 PM The easiest way to compare different land use scenarios is to place all of them on the same Schematic Editor screen grid Each basin can then represent a different land use scenario Because the LID scenario generator only compares runoff volume there is no need to do any routing through a conveyance system or stormwater facility For this example the three basins are assigned the following land uses Basin 1 100 acres C D Shrub Flat Basin 2 100 acres C D Urban Flat Basin 3 50 acres C D Urban Flat 50 acres Parking Flat Each basin is assigned a different POC point of compliance for the LID analysis 142 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Edit View Help Summary Report D Xe Zausumuexsamu cc ALARSA Low Impact Development Scenario Generator as Bypass for POC Groundwater LID Scenario Generator POC To Analyze B Annual 24 T Show Only Selected PERLND NAME Area Surace interow Groundwater Precipitation Evaporation Total Runoff E Acres CID Urban Flati0 5 12782 i5 1487 2385 15421 23 589 6 625 putem ads Mod 5 10 ads VeryStee 20 pofArea 1 1 1 ays Mod 5 1072 51022027 veways Very 20 Hewalks Mod 5 10 Hewalks 51022072 Hewalks Very 20 king Flat 0 5 irking Mod 5 10
14. PCW Cohesion Water Porosity fraction PGW Gravitational Water Porosity fraction UPGW Upper Gravitational Water porosity fraction 161 Bay Area Hydrology Model 2013 User Manual March 2014 Table 6 BAHM2013 Alameda San Mateo HSPF Pervious Parameter Values Part V PERLND No STABNO SRRC SREXP IFWSC DELTA UELFAC LELFAC 1 1 0 1 0 4 0 2 4 2 5 2 1 0 1 0 4 0 2 4 2 5 3 1 0 1 0 4 0 2 4 2 5 4 1 0 1 0 4 0 2 4 2 5 5 1 0 1 0 4 0 2 4 2 5 6 1 0 1 0 4 0 2 4 2 5 7 1 0 1 0 4 0 2 4 2 5 8 1 0 1 0 4 0 2 4 2 5 9 1 0 1 0 4 0 2 4 2 5 10 1 0 1 0 4 0 2 4 2 5 11 1 0 1 0 4 0 2 4 2 5 12 1 0 1 0 4 0 2 4 2 5 13 1 0 1 0 4 0 2 4 2 5 14 1 0 1 0 4 0 2 4 2 5 15 1 0 1 0 4 0 2 4 2 5 16 1 0 1 0 4 0 2 4 2 5 17 1 0 1 0 4 0 2 4 2 5 18 1 0 1 0 4 0 2 4 2 5 19 1 0 1 0 4 0 2 4 2 5 20 1 0 1 0 4 0 2 4 2 5 21 1 0 1 0 4 0 2 4 2 5 22 1 0 1 0 4 0 2 4 2 5 23 1 0 1 0 4 0 2 4 2 5 24 1 0 1 0 4 0 2 4 2 5 25 1 0 1 0 4 0 2 4 2 5 26 1 0 1 0 4 0 2 4 2 5 27 1 0 1 0 4 0 2 4 2 5 28 1 0 1 0 4 0 2 4 2 5 29 1 0 1 0 4 0 2 4 2 5 30 1 0 1 0 4 0 2 4 2 5 31 1 0 1 0 4 0 2 4 2 5 32 1 0 1 0 4 0 2 4 2 5 33 1 0 1 0 4 0 2 4 2 5 34 1 0 1 0 4 0 2 4 2 5 35 1 0 1 0 4 0 2 4 2 5 36 1 0 1 0 4 0 2 4 2 5 37 1 0 1 0 4 0 2 4 2 5 38 1 0 1 0 4 0 2 4 2 5 39 1 0 1 0 4 0 2 4 2 5 40 1 0 1 0 4 0 2 4 2 5 41 1 0 1 0 4 0 2 4 2 5 42 1 0 1 0 4 0 2
15. 31 Bay Area Hydrology Model 2013 User Manual March 2014 7 Save project amp amp Recent files Save St Trapezoidal Pond 1 Mitigated Facility Name Trapezoidal Pond 1 Outlet 1 Facility Type Outlet 2 Outlet 3 Downstream Connections M Precipitation Applied to Facility V Evaporation Applied to Facility Facility Dimensions Facility Bottom Elevation ft Bottom Length ft Bottom Width ft Effective Depth ft Left Side Slope Bottom Side Slope H V Right Side Slope Top Side Slope Auto Pond Quick Pond Facility Dimension Diagram Outlet Structure Data RiserHeight ft 3 H Riser Diameter in Riser Type Notched H Notch Type Rectangular Notch Height ft 0 7223 H Notch Width ft rag 4 Orifice Diameter Height Infiltration Number ft 24 ee ERES S nsi Pond Volume at Riser Head ac ft B72 Show Pond Table OpenTable Initial Stage ft Commercial Toolbox Tide Gate Series Demand Determine Outlet With Tide Gate Move Elements 4 Use Tide Gate Tide Gate Elevation f DownsreemConnecion Save xy Load sy Overflow Elevation ft fo Iterations fo Fl 8 16 13 2013 12 34 PM To save the project click on File in the upper left corner and select
16. Load sy vA dt PerviousT otal Impervious Total Basin Total E E se E hees Deselect Zero Select By 50 16 23 2013 The user extends the connection line to downstream element in this example a pond and left clicks on the destination element This action brings up the From Basin to Conveyance box that allows the user to specify which runoff components to route to the downstream element Stormwater runoff is defined as surface flow interflow Both boxes should be checked Groundwater should not be checked for the standard land development mitigation analysis Groundwater should only be checked when there is observed and documented base flow occurring from the upstream basin From Basin to conveyance Flow From v Surface Flow v Interflow Groundwater After the appropriate boxes have been checked click the OK button 122 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Ele Edit View Help SummaryReport FELGEN TAS i FIRR Sela E Basin 1 Mitigated Subbasin i Designate as Bypass for POC Surface Interflow Groundwater Flows To Saas Mitigate Area in Basin Show Only Selected i Available Impervious Acres Available Pervious Acres A B UrbanMod 5 T 0 o 1 Roads FI BUrban Stee 10 20 BUrban Very ET 520 g Ras m Roads Steep 10 20 E D Forest Flat
17. March 2014 APPENDIX D ADDITIONAL GUIDANCE FOR USING BAHM2013 Scope and Purpose This appendix includes guidance and background information that are not incorporated into the BAHM2013 software but which the user needs to know in order to use BAHM2013 for designing projects in the participating jurisdictions The three main topic areas in this appendix are flagged in the main user manual text by specially formatted notes under the BAHM2013 elements or software features to which they are related Appendix D Topic Relevant Sections in User Manual Infiltration Reduction Factor Infiltration page 114 applicable when specifying characteristics of a facility pond vault tank some LID elements if yes is selected as the Infiltration option Flow Duration Outlet Structures Outlet Structure Configurations pages 108 includes sizing of low flow orifice 113 applicable when specifying and alternative configurations characteristics of a flow duration facility Drawdown drain time for flow Drawdown Analysis screen page 130 duration facilities Additional guidance and references are also discussed at the end of this appendix The sponsoring stormwater programs will revise and expand this section as time and resources allow Check the BAHM2013 website at www bayareahydrologymodel org for the most recent updates Infiltration Reduction Factor The Western Washington Hydrology Model included this factor
18. March 2014 DRY WELL ELEMENT A dry well is similar to the in ground infiltration planter except that there is no bottom discharge pipe or underdrain Water must infiltrate into the native soil underlying the gravel layer of the planter The native soil must have sufficient infiltration capacity to infiltrate all of the stormwater In BAHM2013 the dry well is represented by a specialized application of the gravel trench element available in the LID Toolbox To access the elements in the LID Toolbox menu click on the LID Toolbox bar BAHM2013 a84 File Edit View Help Summary Report Duk te FECALE MTAA EE y T leo Schematic Outlet 1 Outlet 2 Outlet 3 M Pre Pioject Downstream Connection 2 Z Mitiaatea Facility Dry Well a JMaximum Facility Area CalcueteDry Well Facility Dimensions Dry Well Length ft Dry Well Bottom Width ft Material Layers for Dry Well Reservoir Thickness ft EI Top Soil Layer Thickness ft Pro Elements Top Soil Layer Porosity 0 1 Gravel Sand Layer Thickness ft Gravel Sand Layer Porosity 0 1 Infiltration Infiltration Rate Total Volume Infiltrated ac ft Total Volume Through Riser ac ft Total Volume Through Facility ac ft Percent Infiltrated Dry Well Volume at Riser Head ac ft 000 Show Dry Well Table Open Tabe Move Elements Size Dry Well 4 Target o
19. Notch Width feet width of notch cannot be larger than the riser circumference For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section Native Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 114 Use Wetted Surface Area sidewalls Yes if infiltration through the trench side slopes is allowed If infiltration is used then the user should consult the Infiltration discussion on page 114 The infiltration trench does not explicitly include an underdrain However to include an underdrain set the underdrain height and orifice diameter using the orifice input the orifice height is defined as from the bottom of the lowest layer in the trench NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor Gravel trench bed receives precipitation on and evaporation from the trench surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should be checked 59 Bay Area Hydrology Model 2013 User Manual March 2014 SAND FILTER ELEMENT BAHM2013 a24 File Edit View Help Summary Report Del Os SORBED 2 G Dem
20. Test 2 El y Zoom se Clear Creek Solutions BAHM2013 Test2 6 29 2013 Annual Max Peak Values Flow cfs 1960 1965 1970 1975 1980 1985 1990 1995 501 1 Predeveloped tow 801 1 M amp gated tow The hydrograph shows the yearly maximum peak flow values for each time series for the entire simulation period in this example from 1960 through 2000 The graph can be either saved or printed 132 Bay Area Hydrology Model 2013 User Manual March 2014 REPORTS SCREEN BAHMI013 2013 Test 2 File Edit View Hele st Trapezoidal Pond 1 Mitigated Facility TrapezoidalPond 1 Facility Type TrapezoidalPond Outlet 1 Outlet 2 Outlet Downstream Connections Precipitation Applied to Facility Auto Pond Quick Pond v Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft Riser Height h E Bottom Length ft 2 Ri 4 Bottom Width ft p Report New Original text based report Report opens in Wordpad Formatted report with charts in pdf format Report opens in pdf viewer PDF Report v Draft Report Original text based report Landuse Report Commercial Toolbox Original text based r
21. maximum minimum or the sum of the hourly values Click the Export button ale Fe The user provides a file name and gt lt the format or type of file The file O type can be ASCII comma Documents delimited Excel spreadsheet or Access database Click Save to save the exported time Ec series file M ace femme a My Network Save as type asci Flle Places Access Database 140 Bay Area Hydrology Model 2013 User Manual March 2014 LID ANALYSIS SCREEN BAHM2013 2013 Test 2 File Edit View Help Summary Report Dae Se Or Sans ERSTE Trapezoidal Pond 1 Mitigated Facility Name Facility Type Outlet 1 Outlet 2 Outlet 3 0 lo 0 LID Scenario Generator POC To Analyze P H Annual 24 Evaporation Total Runoff IMPLND NAME Commercial Toolbox Move Elements Save EST Units of Inches EC Units of Acre Ft E 16 28 2013 3 15PM The LID tool bar button farthest on the right brings up the Low Impact Development Scenario Generator screen The LID scenario generator can be used to compare the amount of runoff from different land types and combinations The user can quickly see how changing the land use affects surface runoff interflow groundwater and evapotranspiration NOTE The LID scenario generator works only in the Mitigated scenario
22. 141 Bay Area Hydrology Model 2013 User Manual BAHM2013 Ele Edit View Zoom Help March 2014 1 Mitigates Subbasin 1 T Designate as Bypass for Surface Interflow Flows Area in Basin Available Pervious Acres a BShubVepSp20zj 0 Show Only Selected Available Impervious Acres Roads Flat 0 5 Groundwater B Grass Flat 0 5 p Brass Mod 1072 Roads Mod 5 1072 Roads Steep 10 202 B Grass Stee 10 207 Ir Grass Ney 5p20z B Urban Flat 0 5 Roads VerjStee 2072 Root Area Driveways Flat 0 5 5 10 Driveways Mod 5 10 Driveways St 10 20 BUrban Very S 2077 R Forest Flat 0 5 a F Driveways Very 20 I Sidewalks Flat 0 5 C D Forest Mod 5 10 o C D Forest St 10 20 0 M E D ForestVery 20 g Iv C D Shub Flat 0 52 E 17 E 0 ShrubModE 07 IF TD Shiub St SP Commercial Toolbox EJD Shiub Venio 20 7 7 DO GrsMods104 _ 0 Move Elements PerviousTotal Acres Impervious Total gaz Acres es Basin Total Acres Sidewalks Mod 5 10z Siewakssiin2Ug 1 SidewaksVemp20z T PakingModbiU 1 ParkingSteep 10 20 Parking Very 20 5
23. 24 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 25 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 26 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 27 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 28 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 29 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 168 Bay Area Hydrology Model 2013 User Manual March 2014 30 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 31 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 32 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 33 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 34 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 35 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 36 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 37 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 38 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 39 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 40 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 41 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 42 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 43 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 44 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0
24. 4 400 0 0 0 35 0 38 0 45 5 400 0 0 0 33 0 35 0 42 6 400 0 0 0 33 0 35 0 42 7 400 0 0 0 33 0 35 0 42 8 400 0 0 0 33 0 35 0 42 9 400 0 0 0 31 0 33 0 40 10 400 0 0 0 31 0 33 0 40 11 400 0 0 0 31 0 33 0 40 12 400 0 0 0 31 0 33 0 40 13 400 0 0 0 30 0 32 0 38 14 400 0 0 0 30 0 32 0 38 15 400 0 0 0 30 0 32 0 38 16 400 0 0 0 30 0 32 0 38 17 400 0 0 0 30 0 32 0 40 18 400 0 0 0 30 0 32 0 40 19 400 0 0 0 30 0 32 0 40 20 400 0 0 0 30 0 32 0 40 21 400 0 0 0 28 0 30 0 37 22 400 0 0 0 28 0 30 0 37 23 400 0 0 0 28 0 30 0 37 24 400 0 0 0 28 0 30 0 37 25 400 0 0 0 26 0 28 0 35 26 400 0 0 0 26 0 28 0 35 27 400 0 0 0 26 0 28 0 35 28 400 0 0 0 26 0 28 0 35 29 400 0 0 0 25 0 27 0 33 30 400 0 0 0 25 0 27 0 33 31 400 0 0 0 25 0 27 0 33 32 400 0 0 0 25 0 27 0 33 33 400 0 0 0 20 0 23 0 28 34 400 0 0 0 20 0 23 0 28 35 400 0 0 0 20 0 23 0 28 36 400 0 0 0 20 0 23 0 28 37 400 0 0 0 18 0 20 0 25 38 400 0 0 0 18 0 20 0 25 39 400 0 0 0 18 0 20 0 25 40 400 0 0 0 18 0 20 0 25 41 400 0 0 0 15 0 17 0 20 42 400 0 0 0 15 0 17 0 20 43 400 0 0 0 15 0 17 0 20 44 400 0 0 0 15 0 17 0 20 45 400 0 0 0 14 0 15 0 18 160 Bay Area Hydrology Model 2013 User Manual March 2014 46 400 0 0 0 14 0 15 0 18 47 400 0 0 0 14 0 15 0 18 48 400 0 0 0 14 0 15 0 18 MELEV Mean surface elevation of the land segment feet BELV Base elevation for active groundwater feet GWDATM Datum for the groundwater elevation feet
25. Fiat H Notch Type Orifice Diameter Height Number in ft ivl ER s 3 m ab ond Volume at Riser Head ac ft 061 Bhow Pond Table OpenTable Use Tide Gate Tide Gate Elevation ft Overflow Elevation ft The user clicks on the Infiltration option arrow to change infiltration from NO to YES This activates the infiltration input options measured infiltration rate infiltration reduction factor and whether or not to allow infiltration through the wetted side slopes walls 0 Downstream Connection 0 Iterations 0 15 24 2013 X09PM The infiltration reduction factor is a multiplier for the measured infiltration rate and should be less than one It is the same as the inverse of a safety factor For example a safety factor of 2 is equal to a reduction factor of 0 5 Infiltration occurs only through the bottom of the facility if the wetted surface area option is turned off Otherwise the entire wetted surface area is used for infiltration After the model is run and flow is routed through the infiltration facility the total volume infiltrated total volume through the riser total volume through the facility and percent infiltrated are reported on the screen If the percent infiltrated is 100 then there is no surface discharge from the facility The percent infiltrated can be less than 100 as long as the surface discharge does not exceed the flow duration criteria Infiltration facilities hav
26. Sublayer 1 porosity 0 1 0 Sublayer 2 Thickness ft 0 Sublayet 2porosity 01 fo Ino Storage Volume at Top of Pavement ac ft 000 Infiltration Commercial Toolbox Show Pavement Table OpenTable Initial Stage ft es Move Elements 4M 9 Save Load sy x iti _ 6 29 2013 15 03 90 Bay Area Hydrology Model 2013 User Manual March 2014 The permeable pavement element also called porous pavement is an impervious basin element that drains directly to storage layer similar to a gravel trench bed The permeable pavement element is anew BAHM2013 element not previously available in BAHM The permeable pavement element dimensions and parameters are Pavement Length ft Roadway length Pavement Bottom Width ft Roadway width Effective Total Depth ft Height from bottom of permeable pavement subgrade to top of pavement plus at least 0 5 feet extra Bottom Slope ft ft Gravel layer slope or grade The effective volume factor is a value between zero and 1 00 It is only used when the bottom slope is greater than 2 The effective volume factor is the fraction ratio of the average maximum water depth behind a check dam in the gravel layer Sublayer 1 compared to the maximum gravel layer depth Sublayer 1 For example if the average maximum water height is 6 and the gravel depth is 9 then the Effective Volume Factor 0 67 6 9 The eff
27. The listing is in WordPad RTF format If the listing is blank then there have been no HSPF input parameter value changes made 137 Bay Area Hydrology Model 2013 User Manual March 2014 This page has been intentionally left blank 138 Bay Area Hydrology Model 2013 User Manual March 2014 TOOLS SCREEN BAHM2013 2013 Test 2 File Edit View Help Summary Report Duk X856 SX Trapezoidal Pond 1 Facility Name Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections Precipitation Applied to Facility Quick Pond V Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft Riser Height ft B Bottom Length ft 89 2178944 Riser Diameter 4 HSPF Input File Import Export Import Existing Input File Perlnds From Commercial Toolbox Move Elements EH Save xy Load xy SE 5 28 2013 14 PM The Tools screen is accessed with the Tools tool bar second from the right The two purposes of the Tools screen are 1 To allow users to import HSPF PERLND parameter values from existing HSPF UCI files and or view and edit BAHM2013 PERLND parameter values 2 To allow users to export time series datasets To export a time series dataset click on the Export Dataset
28. computations A situation may occur where it is not possible to have both an acceptable pond drawdown retention time and meet the flow duration criteria NOTE The flow duration criteria take precedence unless the user is instructed otherwise by Appendix D or the local municipal permitting agency 130 Bay Area Hydrology Model 2013 User Manual March 2014 HYDROGRAPHS BAHM2013 2013 Test 2 Edit View Help Summary Report Duk se Aegis ee Add Data File Previous Plots d v Record Plots 1 Pan Evap Calabazas 2 Sanlose Start Date 1953 10 01 00 00 Aum EndDate 2000 09 30 24 00 1000 Trapezoidal Pond 1 ALL OUTLETS Mitigated 1001 Trapezoidal Pond 1 STAGE Mitigated DSN to Copy 13 00 PM The user graph plot or all time series data by selecting the Hydrograph tab The Create Graph screen is shown and the user can select the time series to plot the time interval yearly monthly daily or hourly and type of data peaks average or volume The following numbering system is used for the flow time series 500 599 Pre project flow Pre project scenario 700 799 Pre mitigated flow Mitigated scenario before the pond 800 899 Mitigated flow Mitigated scenario after the pond The selected time series are shown To graph the selected time series the user clicks on the Graph button 131 Bay Area Hydrology Model 2013 User Manual March 2014
29. diameter orifice as specified ELBOW RESTRICTOR DETAIL orifices sized and located as required with NTS lowest orifice a minimum of 2 from base Figure 3 18 Flow Restrictor Baffle Riser protection structures Diagrams courtesy of Washington State Department of Ecology 113 Bay Area Hydrology Model 2013 User Manual March 2014 INFILTRATION Infiltration of stormwater runoff is arecommended solution if certain conditions are met These conditions include a soils report testing groundwater protection pre settling and appropriate construction techniques NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor Outlet 1 Facility Type Outlet 2 Outlet 3 Pn Downstream Connections 0 g 0 Pond QuickPond Facility Dimension Diagram Outlet Structure Data Facility Bottom Elevation ft Bottom Length ft Bottom Width ft Effective Depth ft Left Side Slope H V pe HA Measured Infiltration Rate in hr Reduction Factar infilt factor Use Wetted Surface Area sidewalls Total Volume Infiltrated ac ft Total Volume Through Riser ac ft Total Volume Through Facility ac ft Percent Infiltrated Size Infiltration Pond Target 100 Riser Height ft 3 4 Riser Diameter fin 24 4 Riser Type
30. side slopes maximum channel depth and the channel s roughness coefficient Manning s n value NATURAL CHANNEL The user can select channel type and associated I m Manning s n from a table list directly above the Channel Dimension information or directly input the channel s Manning s n value The channel is used to represent a natural or artificial n open channel through which water is routed It can 62 Bay Area Hydrology Model 2013 User Manual March 2014 be used to connect a basin to a pond or a pond to a pond or multiple channels can linked together Channel input information Channel Bottom Width ft Open channel bottom width Channel Length ft Open channel length Manning s n coefficient Open channel roughness coefficient user menu selected or input Slope of Channel ft ft Open channel bottom slope Left Side Slope of Channel ft ft H V ratio of horizontal distance to vertical 0 zero for vertical channel sides Right Side Slope of Channel ft ft H V ratio of horizontal distance to vertical 0 zero for vertical channel sides Maximum Channel Depth ft Height from bottom of channel to top of channel bank Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 114 Use Wetted Surface Area sidewalls Yes if infiltra
31. 0 4 0 2 4 2 5 32 1 0 1 0 4 0 2 4 2 5 33 1 0 1 0 4 0 2 4 2 5 34 1 0 1 0 4 0 2 4 2 5 35 1 0 1 0 4 0 2 4 2 5 36 1 0 1 0 4 0 2 4 2 5 37 1 0 1 0 4 0 2 4 2 5 38 1 0 1 0 4 0 2 4 2 5 39 1 0 1 0 4 0 2 4 2 5 40 1 0 1 0 4 0 2 4 2 5 41 1 0 1 0 4 0 2 4 2 5 42 1 0 1 0 4 0 2 4 2 5 43 1 0 1 0 4 0 2 4 2 5 44 1 0 1 0 4 0 2 4 2 5 45 1 0 1 0 4 0 2 4 2 5 182 Bay Area Hydrology Model 2013 User Manual March 2014 46 1 0 1 0 4 0 2 4 2 5 47 1 0 1 0 4 0 2 4 2 5 48 1 0 1 0 4 0 2 4 2 5 STABNO User s number for the FTABLE in the FTABLES block which contains the outflow properties from the surface storage SRRC Surface Runoff Recession Constant per hour SREXP Surface Runoff Exponent IFWSC Maximum Interflow Storage Capacity when the groundwater elevation is greater than the upper influence elevation inches DELTA groundwater tolerance level used to determine transition between regions when high water table conditions are being simulated UELFAC multiplier on UZSN which gives the upper zone capacity LELFAC multiplier on LZSN which gives the lower zone capacity The selection of the Table 5 and Table 6 default parameter values is based on limited application of these parameters in San Francisco Bay Area by the staff of Clear Creek Solutions Inc NOTE The parameter values should be used with caution and only after consultation with the appropriate local municipal permitting agency o
32. 0 5 0 AForest Mod 5 10 D l r KFerestStee 1020 3 Roads Mod 5 10 Roads Steep 10 20 Roads VerjStee 207 Roof Area AShrub Mod 5 107z 0 Driveways Flat 0 5 2 AShrubStee 10 20 gt AshrubVery 92209 5102 Driveways 510 202 I AGrass Flat 0 5 AGrass 5 10 Driveways Very 2077 Sidewalks Flat 0 5 AGrass Stee 10 207 Albanas n 510 0 5 10202_ fo p Run Predeveloped Run Mitigated Clear All Import Basin Location BForestFlat 0 5 B Fotest Mod 5 1027 0 J B Forest Stee i0 20 D Y Sidewalks Mod 5 1072 Sidewaks 510202 E SidewsksVegp20z Pakng F052 1 M PakingModE 310z D 5 1020 U T Pakingverban 1 s e PerviousT otal p aee Impervious Total Sq Actes Basin Tota B Save xy Load sy j gt H Deselect Zero Select By 50 16 23 2013 2 47 Elements connected by right clicking on the upstream element in this example Basin 1 and selecting and then left clicking on the Connect To Element option By doing so BAHM2013 extends a line from the upstream element to wherever the user wants to connect that element 121 Bay Area Hydrology Model 201
33. 000 Riser Type Flat 4 Material Layers for LID Toolbox Layer Layer2 Layer3 ooo E n 5 Soil Layer 2 GRAVEL Orifice Diameter Height Soi Laver 3 BBAVEL Number in tt Commercial Toolbox 2 tt Hae 4 _Edit Soil Types _ 2 p ai Bg ciu 3 Show Bioretention OpenTable Bioretention Volume at Riser Head ac ft 000 4 Move Elements Native Infiltration No H x _ xml There is a simple bioretention option It is computationally much faster than the standard bioretention Before using the simple option read the note below to understand the limitations of the simple bioretention NOTE The standard bioretention routine uses HSPF Special Actions to check the available engineered soil storage and compares it with the inflow rate Because of the check done by HSPF Special Actions simulations using the bioretention element take much longer than simulations not using the bioretention element Simulations that normally take only seconds may take multiple minutes when one or more bioretention elements are added depending on the computational speed of the computer used One solution to this problem is to use the simple bioretention option check the Use Simple Bioretention box The simple bioretention does not include HSPF Special Actions It is
34. 10 0 10 0 10 0 10 0 10 0 11 0 12 10 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 11 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 12 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 13 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 14 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 15 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 16 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 17 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 18 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 19 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 20 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 21 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 22 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 23 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 24 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 25 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 26 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 27 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 28 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 166 Bay Area Hydrology Model 2013 User Manual March 2014 29 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 30 0 11 0 11 0 11 0 11 0 11 0 11 0 11
35. 2014 Table 1 BAHM2013 Alameda San Mateo Pervious Land Types PERLND No Soil Vegetation Surface Slope 1 A Forest Flat 0 596 2 A Forest Moderate 5 10 3 A Forest Steep 10 20 4 A Forest Very Steep gt 20 5 A Shrub Flat 0 596 6 A Shrub Moderate 5 10 7 A Shrub Steep 10 20 8 A Shrub Very Steep gt 20 9 A Grass Flat 0 596 10 A Grass Moderate 5 10 11 A Grass Steep 10 20 12 A Grass Very Steep gt 20 13 A Urban Flat 0 5 14 A Urban Moderate 5 10 15 A Urban Steep 10 20 16 A Urban Very Steep gt 20 17 B Forest Flat 0 596 18 B Forest Moderate 5 10 19 B Forest Steep 10 20 20 B Forest Very Steep gt 20 21 B Shrub Flat 0 596 22 B Shrub Moderate 5 10 23 B Shrub Steep 10 20 24 B Shrub Very Steep gt 20 25 B Grass Flat 0 5 26 B Grass Moderate 5 10 27 B Grass Steep 10 20 28 B Grass Very Steep gt 20 29 B Urban Flat 0 596 30 B Urban Moderate 5 10 31 B Urban Steep 10 20 32 B Urban Very Steep gt 20 33 C D Forest Flat 0 5 34 C D Forest Moderate 5 10 35 C D Forest Steep 10 20 36 C D Forest Very Steep gt 20 37 C D Shrub Flat 0 5 38 C D Shrub Moderate 5 10 39 C D Shrub Steep 10 20 40 C D Shrub Very Steep gt 20 41 C D Grass Flat 0 5 42 C D Grass Moderate 5 10 43 C D Grass Steep 10 20 44 C D Grass Very Steep gt 20 152
36. 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 42 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 43 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 44 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 45 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 46 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 47 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 48 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 189 Bay Area Hydrology Model 2013 User Manual March 2014 This page has been intentionally left blank 190 Bay Area Hydrology Model 2013 User Manual March 2014 APPENDIX C DEFAULT BAHM2013 HSPF IMPERVIOUS PARAMETER VALUES FOR ALAMEDA SANTA CLARA AND SAN MATEO COUNTIES The default BAHM2013 HSPF impervious parameter values are found in BAHM2013 file defaultpers uci These impervious parameter values have not changed from the original BAHM values The default BAHM2013 HSPF impervious parameter values are based on HSPF calibrations of Castro Valley Creek Alameda Creek and Ross Creek HSPF calibrations of Castro Valley Creek and Alameda Creek are documented in the report AQUA TERRA Consultants 2006 Hydrologic Modeling of the Castro Valley Creek and Alameda Creek Watersheds with the U S EPA Hydrologic Simulation Program FORTRAN HSPF Prepared for Alameda Countywide Clean Water Program Janua
37. AU 5 24 2013 3 48 PM The flow splitter divides the runoff and sends it to two difference destinations The splitter has a primary exit exit 1 and a secondary exit exit 2 The user defines how the flow is split between these two exits The user can define a flow control structure with a riser and one to three orifices for each exit The flow control structure works the same way as the pond outlet structure with the user setting the riser height and diameter the riser weir type flat rectangular notch V notch or Sutro and the orifice diameter and height For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section 64 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Edit View Help Summary Report zgueHmemSoowsusmMuioocsoc Flow Splitter 1 Downstream Connection Both Exits Primary Exit 1 Secondary Exil 2 Trepezoidal Pond 1 Ehannel 1 Upstream Storage Area Length ft Primary Exit 1 Structure Secondary Exit 2 Structure Flow Threshold H Flow Threshold cfs 6 Commercial Toolbox Volume at Top of Storage area ac ft 000 Zz Show Splitter Table OpenTable Move wx Initial Stage ft uc CHE Save Load sy m 1 iti Y 5 24 2013 3 48 PM The second option is that the flow split can be based on
38. Constant Slope of Channel ft ft Maximum Interflow Storage Capacity Left Side Slope HAV A Forest Flat 0 5 Right Side Slope HAV amp Forest Mod 5 1027 Maximum Channel Depth ft A Forest Stee 10 20 A Forest Very gt 20 A Shrub Flat 0 5 Shrub Mod 5 10 A Shrub Stee 10 20 E A Shrub Mew Sp20 Show Wetland Table OpenTable Move Elements A Grass Flat 0 5 t Accept Cancel Save xy Load sy I E 3 EESTI E 6 24 2013 S44PM Commercial Toolbox IDEE The High Groundwater Wetland element is a complex element that should only be used in special applications by advanced BAHM2013 users The purpose of the high groundwater wetland element is to model hydrologic conditions where high groundwater rises to the surface or near the surface and reduces the ability of water to infiltrate into the soil The element can be used to represent wetland conditions with surface ponding where the discharge from the wetland is via a surface release The user is given the choice of using either a natural channel berm weir or control structure to determine the release characteristics The element provides default values for some of the parameters especially as they relate to high groundwater The user should be fully familiar with these parameters and the appropriate values for their site prior to attempting to use this element The high groundwater parameter definitions are shown
39. Flat 0 5 34 C D Forest Moderate 5 10 35 C D Forest Steep 10 20 36 C D Forest Very Steep gt 20 37 C D Shrub Flat 0 5 38 C D Shrub Moderate 5 10 39 C D Shrub Steep 10 20 40 C D Shrub Very Steep gt 20 41 C D Grass Flat 0 5 42 C D Grass Moderate 5 10 43 C D Grass Steep 10 20 44 C D Grass Very Steep gt 20 172 Bay Area Hydrology Model 2013 User Manual March 2014 45 C D Urban Flat 0 596 46 C D Urban Moderate 5 10 47 C D Urban Steep 10 20 48 C D Urban Very Steep gt 20 173 Bay Area Hydrology Model 2013 User Manual March 2014 Table 2 BAHM2013 Santa Clara HSPF Pervious Parameter Values Part I PERLND No LZSN INFILT LSUR SLSUR KVARY AGWRC 1 5 2 0 100 400 0 05 0 8 0 985 2 4 8 0 075 350 0 10 0 8 0 985 3 4 5 0 055 300 0 15 0 8 0 985 4 4 2 0 045 200 0 25 0 8 0 985 5 5 2 0 090 400 0 05 0 8 0 955 6 4 8 0 070 350 0 10 0 8 0 955 7 4 5 0 045 300 0 15 0 8 0 955 8 4 2 0 040 200 0 25 0 8 0 955 9 5 2 0 090 400 0 05 0 8 0 955 10 4 8 0 070 350 0 10 0 8 0 955 11 4 5 0 045 300 0 15 0 8 0 955 12 42 0 040 200 0 25 0 8 0 955 13 5 0 0 060 400 0 05 1 2 0 997 14 4 6 0 050 350 0 10 1 2 0 997 15 4 2 0 040 300 0 15 1 2 0 997 16 3 8 0 030 200 0 25 1 2 0 997 17 5 0 0 080 400 0 05 1 2 0 980 18 4 7 0 060 350 0 10 1 2 0 980 19 4 4 0 045 3
40. Frequency Hydrograp gt 1 4950 1 0058 d lov 0 1476 801 POC 1 Mitigated flow b 0 0968 0 1310 1 4147 0 1982 3 4289 0 1524 1 8018 All Datasets Flow Stage Precip Evap 1 E 3 4135 5 1 3003 0 1431 2 4368 0 1471 0 2131 0 1063 0 3663 16 29 2013 255 PM Flow frequency plots are shown on the left and the 2 5 10 and 25 year frequency values are on the right Flow frequency calculations are based on selecting annual peak flow values and ranking them by their Weibull Plotting Position Bulletin 17B U S Water Resources Council 1981 provides information on the use of the Weibull Plotting Position The Weibull Plotting Position formula is P m a N a b 1 where P probability m rank N number of years a constant b constant The two constants a and b are used to adjust the probability of historical values to more accurately represent extreme events for example 100 year event when the number of years N is not sufficient to produce the appropriate Weibull plotting position For the purposes of the HM requirements which focuses on the range of 10 of the 2 year to the 10 year the constants can be assumed to equal zero This reduces the Weibull equation to 128 Bay Area Hydrology Model 2013 User Manual March 2014 m N 1 Return period Tr years 1 The return period value Tr is used in BAHM2013 to determine the 2 year 5 year 10 year and 25 y
41. Hydrology Model 2013 User Manual March 2014 Alameda Countywide Clean Water Program www cleanwaterprogram org San Mateo Countywide Water Pollution Prevention Program www flowstobay org Santa Clara Valley Urban Runoff Pollution Prevention Program www scvurppp org The BAHM2013 website includes links to specific resources on these websites about stormwater requirements for new and redevelopment projects along with BAHM2013 software and support documents and announcements about BAHM2013 updates and trainings www bayareahydrologymodel org Guidance by Other Agencies Some agencies in other parts of the US have developed extensive guidance for design of stormwater management measures Two manuals are discussed below that provide detailed discussions or examples that may be helpful to users of BAHM although the suitability of these recommendations for Bay Area conditions has not been verified These documents can help provide context and ideas for users for BAHM but adapting these ideas requires the exercise of professional engineering judgment Mention of the procedures and details in these documents does not imply any endorsement or guarantee that they will be appropriate for addressing the Hydromodification Management Standards in Bay Area jurisdictions Stormwater Management Manual for Western Washington SMMWW was prepared by the Washington Department of Ecology for implementation in 19 counties of Western Washington The latest 2
42. Lateral Pervious Flow Basin Mitigated Soil PERLND Type Change Run Scenario Lateral Area ac t Basic Elements Lateral Basin 1 m gt AForest Flat 0 5 Pro Elements Forest Mod 5 10 E A Forest Stee 10 20 AForestVerp gt 20 AShrub Flat 0 5 LID Toolbox AShrub Mod 5 10 A Shrub Stee 10 207 AShrubVery 5 gt 20 A Grass Flat 0 5 Commercial Toolbox _ Accent NN Move Elements 4 CE Save xy Load 38 401 EE Lie 6 14 2013 3 04PM _ Runoff dispersion from impervious surfaces onto adjacent pervious land can be modeled using pervious and impervious lateral basins For example runoff from an impervious parking lot can sheet flow onto an adjacent lawn prior to draining into a stormwater conveyance system This action slows the runoff and allows for some limited infiltration into the pervious lawn soil prior to discharging into a conveyance system The pervious lateral basin is similar to the standard basin except that the runoff from the lateral basin goes to another adjacent lateral basin impervious or pervious rather than directly to a conveyance system or stormwater facility By definition the pervious lateral basin contains only a single pervious land type Impervious area is handled separately with the impervious lateral basin Lateral I Basin The user selects
43. Model 2013 User Manual March 2014 Table 2 BAHM2013 HSPF Impervious Parameter Values Part I IMPLND No LSUR SLSUR NSUR RETSC 1 100 0 05 0 1 0 10 2 100 0 10 0 1 0 09 3 100 0 15 0 1 0 08 4 100 0 25 0 1 0 06 5 100 0 05 0 1 0 10 6 100 0 05 0 1 0 10 7 100 0 10 0 1 0 09 8 100 0 15 0 1 0 08 9 100 0 25 0 1 0 06 10 100 0 05 0 1 0 10 11 100 0 10 0 1 0 09 12 100 0 15 0 1 0 08 13 100 0 25 0 1 0 06 14 100 0 05 0 1 0 10 15 100 0 10 0 1 0 09 16 100 0 15 0 1 0 08 17 100 0 25 0 1 0 06 LSUR Length of surface flow path feet for impervious area SLSUR Slope of surface flow path feet feet for impervious area NSUR Surface roughness Manning s n for impervious area RETSC Surface retention storage inches for impervious area 193 Bay Area Hydrology Model 2013 User Manual March 2014 Table 3 BAHM2013 HSPF Impervious Parameter Values Part II IMPLND No RETS SURS 1 0 00 0 00 2 0 00 0 00 3 0 00 0 00 4 0 00 0 00 5 0 00 0 00 6 0 00 0 00 7 0 00 0 00 8 0 00 0 00 9 0 00 0 00 10 0 00 0 00 11 0 00 0 00 12 0 00 0 00 13 0 00 0 00 14 0 00 0 00 15 0 00 0 00 16 0 00 0 00 17 0 00 0 00 18 0 00 0 00 RETSC Initial surface retention storage inches for impervious area SURS Initial surface runoff inches for impervious area 194 Bay Area Hydrology Model 2013 User Manual
44. Moderate 5 10 16 Parking Steep 10 20 17 Parking Very Steep gt 20 The user does not need to know or keep track of the HSPF IMPLND number That number is used only for internal tracking purposes in the HSPF UCI file created by 2013 44 Bay Area Hydrology Model 2013 User Manual March 2014 TRAPEZOIDAL POND ELEMENT Bay Area Hydrology Model 2013 File Edit View Help Summary Report amp amp De Trapezoidal Pond 1 Mitigated zoidal Pon Facility Type apezoidal Po Outlet 1 Outlet 2 Outlet Y Downstream Connections 1 Precipitation Applied to Facility Facility Dimensions Facility Bottom Elevation ft Bottom Length ft Bottom Width ft Effective Depth ft Left Side Slope HAV Bottom Side Slope Right Side Slope HAV Top Side Slope Infiltration Measured Infiltration Rate in hr Reduction Factorlinfilt factor fo cH Use Wetted Surface Area sidewalls Ng H Total Volume Infiltrated ac ft 0 Total Volume Through Riser ac ft 0 Total Volume Through Facility ac t 0 00 Percent Infiltrated 0 Size Infiltration Pond Target 100 4 Tide Gate Series Demand gt fo Commercial Toolbox Auto Pond Quick Pond Facility Dimension Diagram Outlet Structure Data RiserHeight ft p H Riser Diameter in RiserType 4 Notch Type Orifice Diameter Height Number in
45. Save As 32 Bay Area Hydrology Model 2013 User Manual March 2014 Save As Pag Test1 whm Documents 3 E My Desktop M My Computer File name Test 2 Network Save as type BAHM2013 Project Files l Places Select a file name and save the BAHM2013 project file The user can exit BAHM2013 and later reload the project file with all of its information by going to File Open 33 Bay Area Hydrology Model 2013 User Manual March 2014 8 Exit BAHM2013 HM2013 2013 Test 2 Edit View Help Summary Report New Ctrl Open Ctri o Recent files Save Save As Archive Publish Commercial Toolbox Move Elements GE Save xy Load l YE HE ASHES Or SORBED 2G si Trapezoidal Pond 1 Mitigated Trepezoidal Pond 1 Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections J 7 Piecipitaion Applied to Facilly Quick Pond Facility Dimension Diagram Facility Dimensions _ Outlet Structure Data Facility Bottom Elevation ft RiserHeight ft 3 4 Bottom Length ft E Riser Diameter in Bottom Width ft 21783446 Riser Notched H Effective Depth ft Notch Type Rectangular 24 Left Side Slope HAV 5729 H Bottom Side Slope HAV BO Notch wieth tt far H Right Side Slope Top Side Slope H V Orifice Dia
46. Tool for Analyzing Hydromodification Effects of Development Projects and Sizing Solutions 2006 http www scvurppp w2k com permit c3 docs Bicknell Beyerlein Feng CASQA Paper 9 26 06 pdf The first Bay Area permit to include the new requirements was that of the Santa Clara Valley Urban Runoff Pollution Prevention Program SCVURPPP SCVURPPP conducted an assessment of hydromodification impacts on streams tributary to South San Francisco Bay and developed an HMP Report that describes the results of the assessments and technical studies and how SCVURPPP agencies will meet the hydromodification management requirements On July 20 2005 the Water Board adopted key provisions of the HMP Report into SCVURPPP s permit Subsequently other Bay Area countywide stormwater programs developed and began implementing HMPs in response to similar permit requirements The Alameda Countywide Clean Water Program ACCWP and San Mateo Countywide Water Pollution Prevention Program SMCWPPP HMPs were adopted by the Water Board on March 14 2007 On October 14 2009 the Water Board adopted a Municipal Regional Permit MRP that consolidated all Bay Area Phase I municipal stormwater program permit requirements into one permit The MRP includes the current hydromodification management requirements for the individual stormwater programs Technical Analysis of Hydromodification Controls SCVURPPP and its consultant team completed a literature review and
47. Use Tide Gate ef Tide Gate Elevation ft Downstream Connection al Overflow Elevation ft Iterations ntitial Stage ft em vang E dr lt 16 24 2013 4 17 PM 1 The fifth column used for a second surface outlet manual or outlet structure infiltration or aquifer recharge Aquifer recharge differs from infiltration in how the model separately accounts for it 71 Bay Area Hydrology Model 2013 User Manual March 2014 HIGH GROUNDWATER WETLAND ELEMENT BAHM2013 fe eX Bile Edit View Help Summary Report BEIGEN TAA 2 2 G Element 1 Designate as Bypass for H Runoff Type Surface Interflow Groundwater Downstream Connection 0 10 a High Giroundwater wetland High Groundwater Areafac Average Depth of Surface Pondinalft High Groundwater Outlet Defined by Natural Channel 2 Mean Surface Elevation ft Base Groundwater Elevation ft Channel Type Deep Groundwater Elevation ft Typical Wetland 0 1 re Cohesion Water porosity 0 1 Channel Gravitational Water porosity 0 1 General Channel Data Upper Gravitation Water porosity 0 1 0 Channel Bottom width ft Available Sail Types PERLNDs UpnenZone Stotege Factor Channel Length it Lower Zone Storage Factor Manning n coelficient Check only one Surface Runoff Recession
48. Vd RS 4 ET 34 RES 8 ey xd rc Pond Volume at Riser Head ac ft 0 Show Pond Table OpenTable Initial Stage ft Move nie Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft Overflow Elevation ft ee Save xy Load xy jg Downstream Connection rag Iterations SS Sl In BAHM2013 there is an individual pond element for each type of pond and stormwater control facility The pond element shown above is for a trapezoidal pond This is the most common type of stormwater pond A trapezoidal pond has dimensions bottom length and width depth and side slopes and an outlet structure consisting of a riser and one or more orifices to control the release of stormwater from the pond A trapezoidal pond includes the option to infiltrate runoff if the soils are appropriate and there is sufficient depth to the underlying groundwater table 45 16 14 2013 3 13 PM TRAPEZOIDAL POND Bay Area Hydrology Model 2013 User Manual March 2014 The user has the option to specify that different outlets be directed to different downstream destinations although usually all of the outlets go to a single downstream location Auto Pond will automatically size a trapezoidal pond to meet the required flow duration criteria Auto Pond is available only in the Mitigated scenario Quick Pond can be used to instantly add pond dimensions and an outlet co
49. a number of technical analyses to address key issues for hydromodification management such as the effectiveness of various flow control techniques the range of storm events to be considered for design criteria and examples of flow duration basin sizing for local projects The key findings of these analyses which served as the basis for developing performance criteria for hydromodification controls are described below Effective Design Approaches It has been previously demonstrated that control of peak flows alone is not adequate for erosion control SCVURPPP s studies showed that hydromodification controls designed for discrete event volume control or design storm hydrograph matching do not provide adequate protection of receiving streams The recommended effective method for hydromodification control is flow duration control This approach involves incorporating one or more flow control structures to maintain the magnitude and duration of post project flows at the same level as the pre project flows 1 matching the long term pattern of flow rates and the proportion of time during which they occur for the full distribution of flows within a significant range The flow duration approach considers the entire multi year discharge record as opposed to a single event Flow controls should be SCVURPPP Hydromodification Management Plan Final Report April 2005 www scvurppp org The Contra Costa Clean Water Program CCCWP and the F
50. based on saturation of top soil layer cm hr K relative hydraulic conductivity can be computed using the following Van Genuchten approximation equation Van Genuchten approximation of relative hydraulic conductivity y Equation 2 Ref K 0 8 J Blum et al 2001 0 sat 2 la L where relative hydraulic conductivity K saturated hydraulic conductivity water content 0 residual water content porosity a constant n constant m constant A few issues arise when dealing with multiple subsurface soil layers The K value used in Equation 1 must be computed from the top soil layer Infiltration into the upper soil layer must not exceed the lesser of the maximum percolation rates for each of the soil layers Finally the rate of percolation of the top layer may be reduced because the layer or layers beneath the top layer cannot accept the percolation flux because of existing saturation levels 203 Bay Area Hydrology Model 2013 User Manual March 2014 Percolation through the subsurface layers Water storage and movement through the three subsurface layers will be computed using Darcy s equation as shown below Equation 3 z Where q Darcy flux cm hr K hydraulic conductivity of the porous medium cm hr h total hydraulic head cm z elevation cm The total head h is the sum of the matric head v and the gravit
51. below Cohension water porosity soil pore space in micropores 72 Bay Area Hydrology Model 2013 User Manual March 2014 Gravitational water porosity soil pore space in macropores in the lower and groundwater layers of the soil column Upper gravitation water porosity soil pore space in macropores in the upper layer of the soil column Upper zone storage factor portion of the water stored in macropores in the upper soil layer which will not surface discharge but will percolate evaporate or transpire Lower zone storage factor portion of the water stored in micropores in the lower soil layer which will not gravity drain but will evaporate or transpire NOTE Due to permit restrictions on infiltration for stormwater treatment measures in areas of high groundwater consult with the local municipal permitting agency regarding any project conditions that might involve using this element 73 Bay Area Hydrology Model 2013 User Manual March 2014 LID ELEMENTS The following pages contain information about these LID elements Bioretention In Ground Planter Flow Through Planter Permeable Pavement Dispersion Lateral Basin Pervious Lateral I Basin Impervious Dry Well Infiltration Trench Infiltration Basin Green Roof Rainwater Harvesting 74 Bay Area Hydrology Model 2013 User Manual March 2014 BIORETENTION ELEMENT Thine TA The bioretention element is a landscaped treatment system in
52. below They have been reproduced from Volume III of the Stormwater Management Manual for Western Washington which has more information on the subject removable watertight coupling or flange 2 min 6 min IT plate welded to elbow with orifice as specified elbow restrictor see detail ELBOW RESTRICTOR DETAIL NTS 1 section of pipe attached by gasketed ISOMETRIC Breton NTS NOTES 1 Use a minimum of a 54 diameter type 2 catch basin 2 Outlet Capacity 100 Year developed peak flow treatment 1 4 Frame and ladder or steps offset so A Cleanout gate is visible from top B Climb down space is clear of riser and cleanout gate Frame is clear of curb 5 If metal outlet pipe connects to cement concrete pipe outlet pipe to have smooth O D equal to concrete pipe I D less 1 4 6 Provide at least one 3 X 080 inches support bracket anchored to concrete wall maximum 3 0 vertical spacing 7 Locate elbow restrictor s as necessary to provide minimum clearance as shown 8 Locate additional ladder rungs in structures used access to tanks or vaults to aliow access when catch basin is filled with water Figure 3 17 Flow Restrictor TEE 112 Bay Area Hydrology Model 2013 User Manual March 2014 watertigit coupling EB NOTER 6 min outlet capacity 100 year developed peak flow metal parts corrosion resistant steat parts to elbow with catch basin type 2 minimum 72
53. box 139 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 2013 Test 2 Ele Edit View Help Summary Report Os SOBER DO0 X Trapezoidal Pond 1 Mitigated Facility Name Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections Precipitation Applied to Facility Quick Pond V Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft z Riser Height ft Boo Bottom Length f Riser Diameter in Standard Import Features HSPF Input File Import Export Import Existing Input File Perlnds From Export Datasets Select Datasets azas 1H122 Irrigation for Alameda Creek Watershe 501 POC 1 Predeveloped fl IHI 1H 701 Inflow to POC 1 Mitigated 801 PDC 1 Mitigated flow 1H 1 IH 000 Trapezoidal Pond 1 ALL OUTLETS Mitigated 001 Trapezoidal Pond 1 STAGE Mitigated Commercial Toolbox Start Date SALA Timestep Out z SUM AVG x p Close Save 7 Load B iat 5 28 2013 314 The list of available time series datasets will be shown The user can select the start and end dates for the data they want to export The time step hourly daily monthly yearly can also be specified If the user wants daily monthly or yearly data the user is given the choice of either selecting the
54. button 17 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Edit View Help Summary Report igjaeHuem5eows5uHuoooc X Trapezoidal Pond 1 Mitigated Facility Name Trapezoidal Pond 1 Facility Type Trapezoidal Pond Outlet 1 Outlet 2 Outlet 3 Downstream Connections p v Precipitati Quick Pond Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft Riser Height ft o H Bottom Length ft Riser Diameter in 0 4 Bottom Width ft RiserType Fiat 4 Effective Depth ft Notch Type Left Side Slope H V Bottom Side Slope H V Right Side Slope H V Top Side Slope HAV Orifice Diameter Height Infiltration zi ong Is iin Cees S es uon aio cab 74 Pond Volume at Riser Head ac ft 0 Show Pond Table OpenTable Initial Stage ft Commercial Toolbox Tide Gate Series Demand Move lal Determine Outlet With Tide Gate Use Tide Gate sl po ee Tide Gate Elevation ft D Save xy Load xy Overflow Elevation ft 0 e E f 16 13 2013 1202 PM The point of compliance is shown on the pond element as a small box with the letter and number 1 in the bar chart symbol in the lower right corner The letter A stands for Analysis and designates that this is an analysis location where flow a
55. discharge rates of each Note that wetted surface area can be included in the discharge calculations by adding the infiltration through the wetted surface area to the lower soil layer and the upper surface layer individually This is done by computing the portion of the wetted surface area that is part of the upper surface layer and computing the infiltration independently from the portion of the wetted surface area that is part of the lower soil layers Water Movement Equations There are several equations used to determine water movement from the surface of the bioretention facility through the soil layers and into an underdrain or native infiltration The water movement process can be divided into three different zones 1 Surface ponding and infiltration into the top soil layer soil layer 1 2 Percolation through the subsurface layers 3 Underdrain flow and native infiltration 202 Bay Area Hydrology Model 2013 User Manual March 2014 Surface ponding and infiltration into the top subsurface layer The modified Green Ampt equation Equation 1 controls the infiltration rate into the top soil layer f K qe Equation 1 Ref Rossman 2009 f soil surface infiltration rate cm hr soil porosity of top soil layer 0 soil moisture content of top soil layer Q9 suction head at the wetting front cm F soil moisture content of the top soil layer cm d surface ponding depth cm K hydraulic conductivity
56. does not need to be modified If a 5 day drawdown time is exceeded more than once or twice during the simulation the system may need to be redesigned to reduce the drawdown time The designer should consider additional reductions in impervious area and or LID elements to help reduce the facility size To evaluate the frequency and distribution of larger events in more detail use the Hydrograph tool page 131 to plot monthly peaks for several years at a time of the mitigated post project scenario to get an idea of how often the discharge that corresponds to the 3 day drain time would be exceeded during warmer months when mosquito development times are shortest Flood Control Local flood control design criteria must be obtained from the appropriate agency as well as any other policies or restrictions that may apply to drainage design A single design storm event can be imported as a time series page 66 and applied to the post project scenario instead of the simulated precipitation record If additional live storage is needed it may be added to upper levels of the same facility or provided elsewhere on the site Additional Resources Stormwater Programs have produced guidance documents for new and redevelopment projects in each county which cover all C 3 requirements including hydromodification management These are available from local municipal permitting agencies and also on the following stormwater program websites 198 Bay Area
57. eene 97 DRY WELDLIBEBMENJT ies dad s deu fades 98 xi INFILTRATION TRENGH ELENMIEINT ient es fodere tonos ttes 100 INFILTRATION BASIN ELEMENT 000 0 cc cccccccececececececececececececececececececeeecs 102 GREEN ROOF ELEMENT A eroe eoe e eMe 104 RAINWATER HARVESTING 106 ADDITIONAL INFORMA TION e eoeo00eoeoeoeoeoesososososososssososososososesosososesosesososee 107 OUTLET STRUCTURE 108 AFE TRATION sists o etc Ede 114 AUTO POND AUTO VAULT AUTO 115 STAGE STORAGE DISCHARGE TABLE Ies 118 POINT OF COMPBLEIANGCB itcr n ap eara 119 CONNECTING ELEMENTS reped t reale ara Reste a dada c Te dida Dea 121 ANALYSIS SCREEN Htec t eese ree 125 FOW DURATION eee rene ene tere ek tele docoudedohce tevekezeleet eb ee tole Feeete ed secs Peve ago duo 127 BREOW FREQUENCY dp a ei e dedita Reaves sip edi 128 IB HAWVADIS ATE 130 HYDROGRAPH S eee ut Net n te TED suit a hee 131 REPORTS SGREEN ete te Pede 133 EIDANADLYSIS e ectetur ee 141 OPTIONS ni nn uet n domuit ae M eee Metas 147 DURATION CRITERIA 148 SCALING EAGTORS 55 5 Aude ee eee its 149 TIMESTEP
58. iii agencies of the LOU Participants or their authorized representatives have been advised of the possibility of such damages Software Copyright by Clear Creek Solutions Inc 2013 2014 All Rights Reserved iv FOREWORD The Bay Area Hydrology Model 2013 BAHM2013 is a tool for analyzing the hydromodification effects of land development projects and sizing solutions to mitigate the increased runoff from these projects This section of the User Manual provides background information on the definition and effects of hydromodification the regulatory history for stormwater programs in the San Francisco Bay Region and relevant findings from technical analyses conducted in response to regulatory requirements It also summarizes the current Hydromodification Management Standard and general design approach for hydromodification control facilities which led to the development of the BAHM2013 Effects of Hydromodification Urbanization of a watershed modifies natural watershed and stream processes by altering the terrain modifying the vegetation and soil characteristics introducing pavement and buildings installing drainage and flood control infrastructure and altering the condition of stream channels through straightening deepening and armoring These changes affect hydrologic characteristics in the watershed rainfall interception infiltration runoff and stream flows and affect the supply and transport of sediment in the stream syste
59. interflow shallow subsurface runoff from the basin to the pond Click OK Flow From v Surface Flow Interflow 14 From Basin to Conveyence Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Ele Edit View Help Summary Report Commercial Toolbox Move Elements 2 5 Save xy Load sy amp st Trapezoidal Pond 1 Mitigated Facity Nene memi Feci Outlet 1 Outlet 2 Downstream Connections 7 Precipitation Applied to Quick Pond Facility Dimension Diagram Facility Dimensions _ Outlet Structure Data Facility Bottom Elevation ft Riser Height ft a ES Bottom Length ft Riser Diameter in o 4 Bottom Width ft Riser Type Fiat al Effective Depth ft Notch Type Left Side Slope H V Bottom Side Slope H V Right Side Slope HAV Top Side Slope HAV Infiltration Orifice Diameter Height Number in ft VAT TEES ET i ENS a ee Pond Volume at Riser Head ac ft 0 Show Pond Table Open Tabe Initial Stage ff Tide Gate Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft Overflow Elevation ft Iterations 6 13 2013 11 58AM A line will connect the basin to the pond 15 Bay Area Hydrology Model 2013 User Man
60. larger than the riser circumference For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section 80 Bay Area Hydrology Model 2013 User Manual March 2014 File Edit View Help Summary Report Oe Ss SEES Facility Name Outlet 3 Downstream Connection Eum Facility Type Biorete le F Use simple Bioretention Quick Bioretention Underdrain Used Bioretention Bottom Elevatior 0 Bioretention Dimensions Bioretention Length ft Bioretention Bottom Width ft Freeboard ft Over toad Flooding ft Effective Total Depth ft Bottom slope of bioretention ft ft Pro Elements Top and Bottom side slope ft ft Left Side Slope Right Side Slope HV Material Layers for ow Through Underdrain ac ft Total Outflow ac ft Facility Dimension Diagram Ovelow Outlet Configuration Data Vertical Orifice diameter in npo Vertical Orifice Elevation in 0000 Width of overroad flow ft 0000 Depth ft Soil Layer 1 Soil Layer 2 Soil Layer 3 GRAVEL Edit Soil Types Show Bioretention Open Table Bioretention Volume at Riser Head ac ft 000 Native Infiltration No H The input information required for the vertical orifice plus overflow is Vertical Orifice Diameter inches diameter of vertical opening below
61. less accurate than the standard bioretention option Tests have shown that the simple option should only be used when the bioretention area and volume is relatively small compared to the contributing basin area If in doubt model the bioretention area both ways and see how close the simple answer is to the standard method The standard method will always be more accurate than the simple option 84 Bay Area Hydrology Model 2013 User Manual March 2014 IN GROUND INFILTRATION PLANTER ELEMENT An in ground planter allows stormwater to enter the planter above ground and then infiltrate through the soil and gravel storage layers before exiting through a discharge pipe Water can also infiltrate into the native soil beneath the planter For the purpose of flow control the discharge from the pipe should not exceed the pre project discharge from the project an site for the flow duration range specified by In Ground Infiltration Planter the local jurisdiction In BAHM2013 the in ground planter is represented by a specialized application of the bioretention element available in the LID Toolbox To access the elements in the LID Toolbox menu click on the LID Toolbox bar File Edit View Help Summary Report DB P wm pzusumaossaHucco Facility Downstream Connection Facility Type In Ground Plan Ox MexmumPlenerAren n Szeitration Planter Ursa enu Underdrain Diameter ft Target
62. manually size a pond or other HM facility Click on the Auto Pond button and the Auto Pond screen will appear The user can set the pond depth default 4 feet pond length to width ratio default 1 to 1 pond side slopes default 3 to 1 and the outlet structure configuration default 1 orifice and riser with rectangular notch weir 19 Bay Area Hydrology Model 2013 User Manual March 2014 To optimize the pond design and create the smallest pond possible move the Automatic Pond Adjuster pointer from the left to the right 2 trapezoidal Pond 1 x Automatic Pond Adjuster Predevelope imi 210min 5 10min HM Mitigated Fast Thorough Pond Depth incl 1 ft freeboard A0 ft Pond length to width ratio Li to1 Pond Side Slopes to1 Bottom Length Jft Bottom wiat ft Volume at riser head Choose Outlet Structure 1 orifice amp rectangular notch Progress Create Pond Optimize Pond Accept pond Close ccc The pond does not yet have any dimensions Click the Create Pond button to create initial pond dimensions which will be the starting point for Auto Pond s automated optimization process to calculate the pond size and outlet structure dimensions Running Auto Pond automates the following BAHM2013 processes 1 the hourly Pre project runoff is computed for the 35 50 years of record it varies depending on which rain gage is used 2 the Pre p
63. of increased runoff peak discharge duration and volume from proposed land use changes that impact natural streams wetlands and other Water courses BAHM2013 provides e Auniform methodology for the three South San Francisco Bay Area counties e A more accurate methodology than single event design storms e Aneasy to use software package Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 is based e Continuous simulation hydrology HSPF Actual long term recorded precipitation data Measured pan evaporation data Existing vegetation for pre project conditions Regional HSPF parameters NOTE Because of changes in input format and software architecture original 2007 BAHM project files cannot be read or used by BAHM2013 What s New in BAHM2013 BAHM2013 gives the user greater modeling flexibility options and accuracy than were available in the original BAHM dated 2007 The original BAHM included some simplified approaches to modeling stormwater LID low impact development facilities BAHM2013 includes modeling elements that more accurately represent these stormwater facilities Specific changes and additions in BAHM2013 include e Ability to run on Microsoft Windows 7 and 8 operating systems either on a workstation single computer or network e Improved Auto Pond capabilities to optimize sizing of stormwater ponds and vaults e New bioretention element that accurately represents bioretention and rain g
64. ond 1 Facility Type Outlet 1 Outlet 2 Downstream Connections p Precipitation Applied to Facility AutoPond Quick Pond v Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Bottom Elevation ft g RiserHeight ft 3 4 Bottom Length ft Riser Diameter in fg Bottom Width ft 89 21 otche Original text based report Report opens in Wordpad atted report with charts in pdf format Report opens in pdf viewer 4j PDF Repot _ Draft Report Original text based report Landuse Report Commercial Toolbox Original text based report Parameter Report 16 29 2013 3 05 PM Click on PDF Report button to generate the report file in PDF format 135 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 2013 Test 2 File Edi View Helo Summary Report Osh X818 SES ond Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections i x ez RE Ri Precipitation Applied to Facility Auto Pond Quick Pond v Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft Riser Height ft B Bottom Length ft Piser Diametertin 18 Bottom Width ft 1 i Report New Original text based report Report opens i
65. overflow width at the top of the plate between its supports Drawdown Time and Considerations Flow duration control facilities are designed to detain stormwater on site for an extended period of time The drawdown time is a concern to designers in relation to two areas of design besides hydromodification management 1 Standing water for extended periods provides a potential habitat in which mosquitoes can breed Each Bay Area stormwater program has worked with its local mosquito abatement or vector control agencies to develop guidelines for stormwater facility design these generally recommend that design detention times not exceed 72 hours and under no circumstances should exceed 5 days Provisions for access and inspection by vector control personnel are also required See stormwater C 3 guidance documents at the weblinks under Additional Resources for details of local vector control provisions which apply to both treatment measures and flow duration facilities 2 Flood control design is intended to control peak flows for large sized storms with expected recurrence intervals such as 15 25 or 100 years Flood control 15 Drawdown time also influences the effectiveness of a flow duration control facility for stormwater treatment however under the MRP HM facilities cannot be used as treatment facilities because detention basins are not considered LID treatment 197 Bay Area Hydrology Model 2013 User Manual March 2014 faciliti
66. project site location The county selection can be changed by clicking on the pulldown menu above the map and selecting one of the three Bay Area counties The user can provide site information optional The site name and address will help to identify the project on the Report screen and in the printed report provided to the local municipal permitting agency The user locates the project site on the map screen by using the mouse and left clicking at the project site location Right clicking on the map re centers the view The and buttons zoom in and out respectively The cross hair button zooms out to the full county view The arrow keys scroll the map view 36 Bay Area Hydrology Model 2013 User Manual March 2014 GENERAL PROJECT INFORMATION SCREEN BAHM2013 2013 Test 2 EER File Edit View Help Summary Report Dei Ose SEED OG elie NS Schematic ERE 33 Basin 1 Pre Project SCENARIOS Subbasin Name E Surface Interflow Groundwater Flows Ta E Ss Area in Basin Show Only Selected Available Pervious Acres Available Impervious Acres ajf AForest Flat 0 5 0 jv Roads Flat 0 5 1 2 A Forest Mod 5 10 u Roads Mod 5 10 T AforestStee i02 de S Roads Steep t0202 AForestVery 2072 o Roads VeryStee gt 20 E AShrub Mod 5 107z 0 IV Driveways Flat 0 5 amp ShrubStee 10 2077 0 P Driveways Mod 5 10 T Amevaa
67. range of flows from 1046 of the 2 year flow 0 15 cfs to the 10 year flow 3 77 cfs The horizontal axis is the percent of time that flows exceed a flow value Plotting positions on the horizontal axis typical range from 0 001 to 1 as explained below For the entire 35 to 50 year simulation period depending on the period of record of the precipitation station used all of the hourly time steps are checked to see if the flow for that time step is greater than the minimum flow duration criteria value 0 19 cfs in this example For a 50 year simulation period there are approximately 400 000 hourly values to check Many of them are zero flows The 10 of the Pre project 2 year flow value is exceeded less than 1 of the total simulation period This check is done for both the Pre project flows shown in blue on the screen and the Mitigated flows shown in red 21 Bay Area Hydrology Model 2013 User Manual March 2014 If all of the Mitigated flow duration values in red are to the left of the Pre project flow duration values in blue then the pond mitigates the additional erosive flows produced by the development If the Mitigated flow duration values in red are far to the left of the Pre project flow duration values in blue then the pond can be made smaller and still meet the flow duration criteria BAHM2014 Eje Edi Dc rye gueummows5Hmuccc EIE MIRISA Schematic T s Trapezoidal Pond 1 Mitigated i
68. rans p 5 Load s ave xy Load xy Deselect Zero Select By m eS it 16 13 2013 111 53 First check the Mitigated scenario box and place basin element on the grid 11 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Ele Edit View Help Summary Report DG mm Zusummiessamucoco je OK Basin 1 Mitigate Subbasin T Designate as Bypass for POC Surface Interflow Groundwater Flows Area in Basin Available Pervious Acres a BUibanMod 5 10 0 Show Only Selected Available Impervious Acres BUrban Stee 10 20 BUrban Very ET 520 g Roads Mod 5 10 Roads Steep 10 207 T C D Forest Flat 0 5 o IF C D Forest Mod 5 10 dicc Forest 5110220 o Roads VerySteef gt 20 v Roof Area v Driveways Flat 0 5 DD Forest Veni 20 i CAD Shrub Flat 0 5 0 Driveways Mod 5 10 Driveways 510 202 7 TO Shrub Mod E 107 r 50207 0 I Driveways Very 20 IV Sidewalks Flat 0 5 5 20 5 Dasr CD GiessMod6 102 0 m CAO GressStel0 20 a 177 ED Grass Veye J T 5 0 Sidewalks Mod 5 1022 Siewakssiin2Ug 1 SidewsksVepp20z PakngFli 5 1 Parking Mod 5 10 Parking Steep 10 20 o eel 1 U
69. slope f ft 0 000 Riser Height Above bioretention fc os Left Side Slope HAV noo Riser Diameter in Right Side Slope HV 0 000 RiserType Fat H Material Layers for Layer Layer2 Layer 3 Depth ft 0000 Soil Layer 1 Soil Layer 2 Soil Layer 3 LID Toolbox Orifice Diameter Height Number in ft Commercial Toolbox Eis 1 o zd o yp b Ap it Soil es 2h N 3d m Show Bioretention OpenTable Bioretention Volume at Riser Head 000 Native Infiltration Savexy Load xy xr vae 82 Bay Area Hydrology Model 2013 User Manual March 2014 To use the underdrain click the Underdrain Used box and input an underdrain diameter feet and the underdrain orifice diameter inches The bottom of the underdrain pipe is set by the user based on the offset inches above the bottom of the lowest engineered soil layer Underdrain Used if C or D soil Underdrain Diameter ft Underdrain pipe diameter C or D soil The engineered soil layer fills with stormwater from the top on down to where it can drain to the native soil if Native Infiltration is set to YES and or the underdrain pipe if Underdrain Used box is checked Water enters the underdrain when the engineered soil becomes saturated down to the top of the underdrain The underdrain pipe fills and conveys wat
70. that automatically loads appropriate parameters and meteorological data and runs continuous simulations of site runoff to generate flow duration curves a module for sizing or checking the control measure to achieve the hydromodification control standard and a reporting module The HSPF hydrology parameter values used in BAHM2013 are based on calibrated watersheds located in the San Francisco Bay Area two Alameda County watersheds and two Santa Clara County watersheds BAHM2013 uses one or more long term local precipitation gages for each of the three South Bay counties and then scales the precipitation to the user s site using mean annual precipitation maps developed by local flood control districts or published as NOAA rainfall maps BAHM2013 computes stormwater runoff for a site selected by the user BAHM2013 runs HSPF in the background to generate an hourly runoff time series from the available rain gauge data over a number of years Stormwater runoff is computed for both pre project and post project land use conditions Then another part of the BAHM2013 routes the post project stormwater runoff through a stormwater control facility of the user s choice BAHM2013 uses the pre project peak flood value for each water year to compute the pre project 2 through 100 year flood frequency values The post project runoff 2 through 100 year flood frequency values are computed at the outlet of the proposed stormwater facility The model routes the po
71. the pervious lateral basin land type by checking the appropriate box on the Available Soil Types Tools screen This information is automatically placed in the Soil PERLND Type box above Once entered the land type can be changed by clicking on the Change button on the right The user enters the number of acres represented by the lateral basin land type 95 Bay Area Hydrology Model 2013 User Manual March 2014 If the lateral basin contains two or more pervious land use types then the user should create a separate lateral basin for each 96 Bay Area Hydrology Model 2013 User Manual March 2014 LATERAL I BASIN ELEMENT Impervious Bay Area Hydrology Model 2013 6 File Edit View Help Summary Report Dc Agta ea Os SBE od G eb Fe e SS Be ema m alera a SCENARIOS Element Name Lateral Basin 1 Designate as Bypass for Runoff Type Surface Interflow Groundwater i Pre Project Downstream Connection 0 g g x Element Type Lateral Impervious Flow Basin r Mitigated r Impervious IMPLND Type change Run Scenario Lateral Area ac 0 Basic Element S Lateral 1 Beas eaa Pro Elements Roads Flat 0 5 je Roads Mod 5 10 I Roads Steep 10 20 Roads VeryStee 20 UD Toolbox I RaofArea Driveways Flat 0 5 Driveways Mod 5 10 Driveways St 10 20 Driveways Very gt 20 Comme
72. the pond and should include at least one foot of freeboard above the riser The pond s original depth will be used when optimizing an existing pond changing the value in the Pond Depth text box will override any previous set depth value The default depth is 4 feet Pond Length to Width Ratio This bottom length to width ratio will be maintained regardless of the pond size or orientation The default ratio value is 1 0 Pond Side Slopes Auto Pond assumes that all of the pond s sides have the same side slope The side slope is defined as the horizontal distance divided by the vertical A typical side slope is 3 3 feet horizontal to every 1 foot vertical The default side slope value is 3 Choose Outlet Structure The user has the choice of either 1 orifice and rectangular notch or 3 orifices If the user wants to select another outlet structure option then the pond must be manually sized Create Pond This button creates a pond when the user does not input any pond dimensions or outlet structure information Any previously input pond information will be deleted Optimize Pond This button optimizes an existing pond It cannot be used if the user has not already created a pond Accept Pond This button will stop the Auto Pond routine at the last pond size and discharge characteristics that produce a pond that passes the flow duration criteria Auto Pond will not stop immediately if the flow duration criteria have not yet been met Th
73. top layer standard soil mix for bioretention facilities SMMWW 15 the Washington State Department of Ecology required top layer standard soil mix for bioretention facilities Wilting wilting point 0 1 Porosity saturated moisture content 0 1 K Sat maximum saturated hydraulic conductivity cm hr VG n Van Genuchten number from literature A alpha constant L lambda constant BPH bubbling pressure head cm Table 1 values are from Schaap and Leij 1998 soil parameter estimations using Rosetta The water movement through the soil column calculations are based on the methodology described in Appendix E Bioretention Modeling Methodology The native soil infiltration is input by the user and is assumed to be constant throughout the year Inflow to the bioretention facility can exceed the engineered soil infiltration rate When this occurs the extra water ponds on the surface of the bioretention area The extra water can then infiltrate into the soil during the next time step or can flow out of the bioretention facility through its surface outlet if the ponding exceeds the surface outlet s storage JB1 Runoff in both the surface storage and engineered soil storage is available for evapotranspiration Surface storage evapotranspiration is set to the potential evapotranspiration the engineered soil evapotranspiration pan evaporation coefficient is set to 0 50 to reflect reduced evapotranspiration from the engineered soil
74. vegetation has been divided into forest shrub and non turf grass and refers to the natural non planted vegetation In contrast the developed landscape will consist of urban vegetation lawns flowers planted shrubs and trees Land slope is divided into flat 0 596 moderate 5 109406 steep 10 20 and very steep 220 land slopes HSPF parameter values in BAHM2013 have been adjusted for the different soil vegetation and land slope categories BAHM2013 HSPF soil parameter values take into account the hydrologic effects of land development activities that result from soil compaction when Urban is specified Impervious areas are divided into five types with four different slopes see Table 2 The five types are roads roofs driveways sidewalks and parking The slope categories are the same as for the pervious land use flat moderate steep and very steep 43 Bay Area Hydrology Model 2013 User Manual March 2014 Table 2 BAHM2013 Impervious Land Types IMPLND No Surface Slope 1 Roads Flat 0 596 2 Roads Moderate 5 10 3 Roads Steep 10 20 4 Roads Very Steep gt 20 5 Roof Area All 6 Driveways Flat 0 596 7 Driveways Moderate 5 10 8 Driveways Steep 10 20 9 Driveways Very Steep gt 20 10 Sidewalks Flat 0 5 11 Sidewalks Moderate 5 10 12 Sidewalks Steep 10 20 13 Sidewalks Very Steep gt 20 14 Parking Flat 0 596 15 Parking
75. 0 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 21 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 22 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 23 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 24 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 25 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 26 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 27 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 28 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 29 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 188 Bay Area Hydrology Model 2013 User Manual March 2014 30 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 31 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 32 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 33 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 34 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 35 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 36 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 37 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 38 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 39 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 40 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 41 0 40 0
76. 0 11 0 11 0 11 0 11 0 11 31 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 32 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 33 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 34 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 35 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 36 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 37 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 38 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 39 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 40 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 41 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 42 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 43 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 44 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 45 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 46 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 47 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 48 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 167 Bay Area Hydrology Model 2013 User Manual March 2014 Table 9 BAHM2013 Alameda San Mateo HSPF Pervious Parameter Values Monthly Lower Zone Evapotranspiration PERLND No JAN FEB MA
77. 0 5 o Ir Forest 511020 0 gt 202 Driveways Flat 0 5 CO Forest Veg 20 p T smera 1 E DShubModE TOz r 10200 fo Driveways Mod 5 10 M Driveways S1020 Driveways Vew gt 202 O v Sidewaks F052 E D Shrub Verl 2022 0 Sidewalks Mod 5 10z Disa 0 E 70 51 511020 _ 0 T i T 5 5 B T E Ci Urban Moat10 T Pakngvegpzox Commercial Toolbox CO Uibanstio202 B a M z Move Elements PerviousTotal B ees CH see 1 Exec Deselect Zero Select By Go vol H 16 28 2013 2 51 PM The final screen will look like the above screen The basin information screen on the right will show that Basin 1 surface and interflow flows to Trapezoidal Pond 1 groundwater is not connected 123 Bay Area Hydrology Model 2013 User Manual March 2014 This page has been intentionally left blank 124 Bay Area Hydrology Model 2013 User Manual March 2014 ANALYSIS SCREEN BAHM2013 2013 Test 2 Edit View Help Summary Report Dei X58 ggsummeouws5iauucsoc Analysis 2 Sanlose 22 Calculated Irrigation for 501 POC 1 Predeveloped flow T Seas
78. 0 5 0 3 0 01 44 0 0 0 01 0 0 5 0 3 0 01 45 0 0 0 01 0 3 5 1 7 0 10 164 Bay Area Hydrology Model 2013 User Manual March 2014 46 0 0 0 01 0 3 5 1 7 0 10 47 0 0 0 01 0 3 5 1 7 0 10 48 0 0 0 01 0 3 5 1 7 0 10 CEPS Initial interception storage inches SURS Initial surface runoff inches UZS Initial Upper Zone Storage inches IFWS Initial interflow inches LZS Initial Lower Zone Storage inches AGWS Initial Active Groundwater storage inches GWVS Initial Groundwater Vertical Slope feet feet 165 Bay Area Hydrology Model 2013 User Manual March 2014 Table 8 BAHM2013 Alameda San Mateo HSPF Pervious Parameter Values Monthly Interception Storage inches PERLND No JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 2 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 3 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 4 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 5 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 6 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 7 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 8 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 9 0 12 0 12 0 12 0 11 0 10 0
79. 0 5 00 7 30 0 85 8 30 Amended 2 5 in hr 0 0800 0 470 1 500 6 50 7 20 0 90 8 20 Amended 3 0 in hr 0 0750 0 480 1 600 7 62 7 10 1 00 8 10 Amended 5 in hr 0 0700 0 490 2 200 13 00 6 90 1 30 7 90 SMMWW 0 0650 0 850 3 000 15 24 6 50 1 40 7 50 Amended 15 in hr 0 0600 0 480 3 200 39 00 6 30 2 10 7 30 ASTM 1 0 0900 0 410 1 500 2 54 7 50 0 75 8 50 ASTM 2 0 0825 0 420 1 550 5 08 7 30 0 88 8 30 ASTM 3 0 0750 0 430 1 600 7 62 7 10 1 00 8 10 ASTM 4 0 0725 0 440 1 650 10 16 7 00 1 15 8 00 ASTM 5 0 0700 0 450 1 700 12 70 6 90 1 30 7 90 ASTM 6 0 0675 0 460 1 850 15 24 6 50 1 40 7 50 ASTM 7 0 0667 0 470 2 000 17 78 6 45 1 50 7 45 ASTM 8 0 0659 0 480 2 150 20 32 6 43 1 58 7 43 ASTM 9 0 0651 0 490 2 300 22 86 6 41 1 66 7 41 ASTM 10 0 0643 0 500 2 450 25 40 6 39 1 74 7 39 77 Bay Area Hydrology Model 2013 User Manual March 2014 ASTM 11 0 0635 0 510 2 600 27 94 6 37 1 82 7 37 ASTM 12 0 0627 0 520 2 750 30 48 6 35 1 90 7 35 ASTM 13 0 0619 0 530 2 900 33 02 6 33 1 98 7 33 ASTM 14 0 0611 0 540 3 050 35 56 6 31 2 06 7 31 ASTM 15 0 0603 0 550 3 200 39 00 6 30 2 14 7 30 ASTM 24 32 0 0590 0 550 3 200 39 00 6 25 2 25 7 20 ASTM 35 46 0 0550 0 550 3 250 90 10 6 20 2 30 7 00 ASTM 50 0 0500 0 550 3 300 127 00 6 15 2 35 6 80 ASTM 60 0 0490 0 550 3 350 152 40 6 10 2 40 6 40 ASTM 100 0 0450 0 550 3 400 254 00 6 05 2 45 6 00 BAHM 5 is the San Francisco Bay Municipal Regional Permit required
80. 00 ey 2 255556 1 046751 2 214533 0 355000 0 000000 2 333333 1 051331 2 296125 0 361069 0 000000 2 411111 1 055922 2 378074 0 367037 0 000000 2 488889 1 060522 2 460380 0 372910 0 000000 HE ul T 2 566667 1 065132 2 543044 0 378692 0 000000 Y ia H 44 82 644444 1 069752 2 626067 0 384387 0 000000 15 24 2013 The stage storage discharge table hydraulically represents facility that requires stormwater routing The table is automatically generated by BAHM2013 when the user inputs storage facility dimensions and outlet structure information BAHM2013 generates 91 lines of stage surface area storage surface discharge and infiltration values starting at a stage value of zero facility bottom height and increasing in equal increments to the maximum stage value facility effective depth When the user or BAHM2013 changes a facility dimension for example bottom length or an orifice diameter or height the model immediately recalculates the stage storage discharge table The user can input to BAHM2013 a stage storage discharge table created outside of 2013 To use a stage storage discharge table created out of BAHM2013 the SSD Table element is required see page 67 See the SSD Table element description below for more information on how to load such a table to BAHM2013 program 118 Bay Area Hydrology Model 2013 User Manual March 2014 POINT OF COMPLIANCE BAHM2013 allows for multiple points o
81. 00 0 15 1 2 0 980 20 4 1 0 035 200 0 25 1 2 0 980 21 5 0 0 070 400 0 05 1 2 0 950 22 4 7 0 055 350 0 10 1 2 0 950 23 4 4 0 040 300 0 15 1 2 0 950 24 4 1 0 030 200 0 25 1 2 0 950 25 5 0 0 070 400 0 05 1 2 0 950 26 4 7 0 055 350 0 10 1 2 0 950 27 4 4 0 040 300 0 15 1 2 0 950 28 4 1 0 030 200 0 25 1 2 0 950 29 4 8 0 050 400 0 05 1 8 0 995 30 4 4 0 040 350 0 10 1 8 0 995 31 4 0 0 030 300 0 15 1 8 0 995 32 3 6 0 025 200 0 25 1 8 0 995 33 4 8 0 050 400 0 05 2 0 0 980 34 4 5 0 045 350 0 10 2 0 0 980 35 4 2 0 035 300 0 15 2 0 0 980 36 4 0 0 030 200 0 25 2 0 0 980 37 4 8 0 045 400 0 05 2 0 0 950 38 4 5 0 040 350 0 10 2 0 0 950 39 4 2 0 030 300 0 15 2 0 0 950 40 4 0 0 025 200 0 25 2 0 0 950 41 4 8 0 045 400 0 05 2 0 0 950 42 4 5 0 040 350 0 10 2 0 0 950 43 4 2 0 030 300 0 15 2 0 0 950 44 4 0 0 025 200 0 25 2 0 0 950 45 4 6 0 040 400 0 05 3 0 0 995 174 Bay Area Hydrology Model 2013 User Manual March 2014 46 4 2 0 030 350 0 10 3 0 0 995 47 3 8 0 022 300 0 15 3 0 0 995 48 3 5 0 020 200 0 25 3 0 0 995 LZSN Lower Zone Storage Nominal inches INFILT Infiltration inches per hour LSUR Length of surface flow path feet SLSUR Slope of surface flow path feet feet KVARY Variable groundwater recession AGWRC Active Groundwater Recession Constant per day 175 Bay Area Hydrology Model 2013 User Manual March 2014 Table 3 BAHM2013 Santa Clara HSPF Pervious Parameter V
82. 01 0 0 5 0 3 0 01 35 0 0 0 01 0 0 5 0 3 0 01 36 0 0 0 01 0 0 5 0 3 0 01 37 0 0 0 01 0 0 5 0 3 0 01 38 0 0 0 01 0 0 5 0 3 0 01 39 0 0 0 01 0 0 5 0 3 0 01 40 0 0 0 01 0 0 5 0 3 0 01 41 0 0 0 01 0 0 5 0 3 0 01 42 0 0 0 01 0 0 5 0 3 0 01 43 0 0 0 01 0 0 5 0 3 0 01 44 0 0 0 01 0 0 5 0 3 0 01 45 0 0 0 01 0 3 5 1 7 0 10 184 Bay Area Hydrology Model 2013 User Manual March 2014 46 0 0 0 01 0 3 5 1 7 0 10 47 0 0 0 01 0 3 5 1 7 0 10 48 0 0 0 01 0 3 5 1 7 0 10 CEPS Initial interception storage inches SURS Initial surface runoff inches UZS Initial Upper Zone Storage inches IFWS Initial interflow inches LZS Initial Lower Zone Storage inches AGWS Initial Active Groundwater storage inches GWVS Initial Groundwater Vertical Slope feet feet 185 Bay Area Hydrology Model 2013 User Manual March 2014 Table 8 BAHM2013 Santa Clara HSPF Pervious Parameter Values Monthly Interception Storage inches PERLND No JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 2 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 3 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 4 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 5 0 13 0 13 0 13 0 14 0 15 0
83. 01 Minimum 2 Maximum f Seasonal Durations mm dd Servae Embase 16 13 2013 12 21 PM Pond drawdown retention time is computed Analysis screen NOTE This information is not required for basic sizing of the flow duration facility but can assist the user in minimizing risk of vector mosquito breeding problems See page 130 for more descriptions of this BAHM2013 feature and Appendix D for discussion and references for these requirements Click on the Stage tab at the bottom to get the Mitigated pond stage time series 26 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Ele Edit View Help Summary Report Duk x8 ga en mid ewig occ Analysis Drawdown Analysis Select Stage dataset below to analyze Analyze Stage Pond Drain Time days Stage feet Percent of Total Run Time Max Stage 001 Minimum 2 Maximum T Seasonal Durations mm dd p 65 13 2013 12 22 PM Click on the tab labeled Drawdown This is where the pond drawdown retention time results will be shown 27 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Bile Edit View Help Summary Report Du Se irueumimexusuHusoo oc Analysis Drawdown Analysis Select analysis for 1001 Trapezoidal Pond 1 STAGE Mitigated Analyze St
84. 012 edition in 5 volumes is on the Web at http www udfcd org downloads down_critmanual htm Design recommendations from this manual were the basis for many features of the WWHM that have been carried over into BAHM Portions of Volume 3 Hydrology that may be of interest to project designers include e Pages 3 2 through 3 18 illustrate several types of roof downspout controls simple pre engineered designs for infiltrating and or dispersing runoff from roof areas in order to reduce runoff volume and or increase potential groundwater recharge e Pages 3 50 to 3 63 discuss outlet control structures their maintenance and source equations modeled into WWHM and BAHM e Pages 3 75 to 3 93 regarding Infiltration Reduction Factor Urban Storm Drain Criteria Manual by the Denver Urban Drainage and Flood Control District is on the Web at http www udfcd org downloads down_critmanual htm Volume 3 covers design of extended detention basins on pages S 66 through S 77 and structural details shown on pages SD 1 to SD 16 Although these designs are not 199 Bay Area Hydrology Model 2013 User Manual March 2014 presented for hydromodification management control the perforated plate design concept allows fine tuning of drawdown times and is adaptable for use in flow duration facilities 200 Bay Area Hydrology Model 2013 User Manual March 2014 APPENDIX E BIORETENTION MODELING METHODOLOGY Water Movement Through The Soil Column Wate
85. 15 0 15 0 15 0 15 0 15 0 14 0 13 6 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 7 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 8 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 9 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 10 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 11 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 12 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 13 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 14 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 15 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 16 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 17 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 18 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 19 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 20 0 15 0 15 0 15 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 18 21 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 22 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 23 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 24 0 13 0 13 0 13 0 14 0 15 0 15 0 15 0 15 0 15 0 15 0 14 0 13 25 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 26 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 27 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12 28 0 12 0 12 0 12 0 11 0 10 0 10 0 10 0 10 0 10 0 10 0 11 0 12
86. 2 0 0 9 2 2 0 02 0 0 10 2 2 0 02 0 0 11 2 2 0 02 0 0 12 2 2 0 02 0 0 13 2 2 0 06 0 0 14 2 2 0 06 0 0 15 2 2 0 06 0 0 16 2 2 0 06 0 0 17 2 2 0 12 0 0 18 2 2 0 12 0 0 19 2 2 0 12 0 0 20 2 2 0 12 0 0 21 2 2 0 12 0 0 22 2 2 0 12 0 0 23 2 2 0 12 0 0 24 2 2 0 12 0 0 25 2 2 0 12 0 0 26 2 2 0 12 0 0 27 2 2 0 12 0 0 28 2 2 0 12 0 0 29 2 2 0 36 0 0 30 2 2 0 36 0 0 31 2 2 0 36 0 0 32 2 2 0 36 0 0 33 3 2 0 15 0 0 34 3 2 0 15 0 0 35 3 2 0 15 0 0 36 3 2 0 15 0 0 37 3 2 0 15 0 0 38 3 2 0 15 0 0 39 3 2 0 15 0 0 40 3 2 0 15 0 0 41 3 2 0 15 0 0 42 3 2 0 15 0 0 43 3 2 0 15 0 0 44 3 2 0 15 0 0 45 3 2 0 45 0 0 156 Bay Area Hydrology Model 2013 User Manual March 2014 46 3 2 0 45 0 0 47 3 2 0 45 0 0 48 3 2 0 45 0 0 INFEXP Infiltration Exponent INFILD Infiltration ratio maximum to mean DEEPER Fraction of groundwater to deep aquifer or inactive storage BASETP Base flow from groundwater Evapotranspiration fraction AGWETP Active Groundwater Evapotranspiration fraction 157 Bay Area Hydrology Model 2013 User Manual March 2014 Table 4 BAHM2013 Alameda San Mateo HSPF Pervious Parameter Values Part III PERLND No CEPSC UZSN NSUR INTFW IRC LZETP 1 see Table 8 0 45 0 35 2 25 0 60 see Table 9 2 see Table 8 0 35 0 35 2 00 0 50 see
87. 3 File Edit View Help Summary Report Oem Subbasin Name Designate as Bypass for POC Interflow Groundwater Show Only Selected Available Impervious Acres Roads Flat 0 5 Roads Mod 5 10 Point of Compliance DR Roads Steep 10 20 1 na Roads Vente 20 2 e 2 Hoof Area D Flat 0 572 Pan Evap Factor 1 lock this factor p Driveways Mod 10 E M Driveways 51022027 T D veways Vene 207 M Sidewaks FOSA O I Sidewalks Mod 5 10 Sidewaks 59110202 M SidewaksVegp20z p PakmgFlpsz O PakingMod5 0z 1 PakigSteep 1020 PakmgVeyo2Uz 1 Restore Defaults Commercial Toolbox Daras 527 xlr 05 7 Move mr PerviousTotal Acres e 4 Toa Actes mi Basin Total Acres Save xy Load xy Deselect Zero Select By s IE 16 23 2013 The user can change the scaling factors for precipitation minimum and maximum pan evaporation NOTE Any change in default scaling factors requires approval by the local municipal permitting agency or Appendix D Click on the Update button once all of the changes have been made To return to the default values click on the Restore Defaults button 149 Bay Area Hydrology Model 2013 User Manual March 2014 TIMESTEP BAHM2013 File Edit
88. 3 User Manual March 2014 BAHM2013 EJES Ele Edit View Help Summary Report Duk ie Schematic SCENARIOS OPre Project lt Basin 1 Mitigated Flows 7 Mitigated Run Scenario Area in Basin Available Pervious Acres Subbasin Name E Designate as Bypass for POC Surface Interflow Tapes Groundwater f Show Only Selected Available Impervious Acres g A Forest Flat 0 5 0 Roads Flat 0 5 amp Fotest Mod 5 10 0 Roads Mod 5 10 T Roads Steep 10 202 amp ForestVery 20 2 0 I 5 0 5 Roads VerjStee 202 Roof Area T AShrub Mod 5 107z 0 1 0 5 amp Shrub Stee 10 2077 g E AShrubVery S 207 0 Driveways Mod 5 10 Driveways St 10 20 ESEA 0 5 10 g Driveways Very 20 Sidewalks Flat 0 572 Sidewalks Mod 5 107z I AGrass Stee 10 207 o AGrass Vey 5 gt 20 0 0 AuibanMods107 _ 17 5 0202 _ 52 fo T BForestrieyo52 r BfoesWodEiOE o 17 Sidewalks 510 2020 SidewaksVegp207 10 PakmgStepiD20 Jo T PakingVewb2n2 1 Commercial Toolbox Move Elements 4 ey Save xy
89. 4 46 400 0 0 0 14 0 15 0 18 47 400 0 0 0 14 0 15 0 18 48 400 0 0 0 14 0 15 0 18 MELEV Mean surface elevation of the land segment feet BELV Base elevation for active groundwater feet GWDATM Datum for the groundwater elevation feet PCW Cohesion Water Porosity fraction PGW Gravitational Water Porosity fraction UPGW Upper Gravitational Water porosity fraction 181 Bay Area Hydrology Model 2013 User Manual March 2014 Table 6 BAHM2013 Santa Clara HSPF Pervious Parameter Values Part V PERLND No STABNO SRRC SREXP IFWSC DELTA UELFAC LELFAC 1 1 0 1 0 4 0 2 4 2 5 2 1 0 1 0 4 0 2 4 2 5 3 1 0 1 0 4 0 2 4 2 5 4 1 0 1 0 4 0 2 4 2 5 5 1 0 1 0 4 0 2 4 2 5 6 1 0 1 0 4 0 2 4 2 5 7 1 0 1 0 4 0 2 4 2 5 8 1 0 1 0 4 0 2 4 2 5 9 1 0 1 0 4 0 2 4 2 5 10 1 0 1 0 4 0 2 4 2 5 11 1 0 1 0 4 0 2 4 2 5 12 1 0 1 0 4 0 2 4 2 5 13 1 0 1 0 4 0 2 4 2 5 14 1 0 1 0 4 0 2 4 2 5 15 1 0 1 0 4 0 2 4 2 5 16 1 0 1 0 4 0 2 4 2 5 17 1 0 1 0 4 0 2 4 2 5 18 1 0 1 0 4 0 2 4 2 5 19 1 0 1 0 4 0 2 4 2 5 20 1 0 1 0 4 0 2 4 2 5 21 1 0 1 0 4 0 2 4 2 5 22 1 0 1 0 4 0 2 4 2 5 23 1 0 1 0 4 0 2 4 2 5 24 1 0 1 0 4 0 2 4 2 5 25 1 0 1 0 4 0 2 4 2 5 26 1 0 1 0 4 0 2 4 2 5 27 1 0 1 0 4 0 2 4 2 5 28 1 0 1 0 4 0 2 4 2 5 29 1 0 1 0 4 0 2 4 2 5 30 1 0 1 0 4 0 2 4 2 5 31 1 0 1
90. 4 2 5 43 1 0 1 0 4 0 2 4 2 5 44 1 0 1 0 4 0 2 4 2 5 45 1 0 1 0 4 0 2 4 2 5 162 Bay Area Hydrology Model 2013 User Manual March 2014 46 1 0 1 0 4 0 2 4 2 5 47 1 0 1 0 4 0 2 4 2 5 48 1 0 1 0 4 0 2 4 2 5 STABNO User s number for the FTABLE in the FTABLES block which contains the outflow properties from the surface storage SRRC Surface Runoff Recession Constant per hour SREXP Surface Runoff Exponent IFWSC Maximum Interflow Storage Capacity when the groundwater elevation is greater than the upper influence elevation inches DELTA groundwater tolerance level used to determine transition between regions when high water table conditions are being simulated UELFAC multiplier on UZSN which gives the upper zone capacity LELFAC multiplier on LZSN which gives the lower zone capacity The selection of the Table 5 and Table 6 default parameter values is based on limited application of these parameters in San Francisco Bay Area by the staff of Clear Creek Solutions Inc NOTE The parameter values should be used with caution and only after consultation with the appropriate local municipal permitting agency or guidance provided in Appendix D Different values should only be selected following detailed local soil analysis a thorough understanding of the parameters and algorithms and consultation with the appropriate local municipal permitting agency 163 Bay Area Hy
91. 5 30 4 1 0 040 350 0 10 1 8 0 995 31 3 9 0 030 300 0 15 1 8 0 995 32 3 4 0 025 200 0 25 1 8 0 995 33 4 0 0 045 400 0 05 2 0 0 980 34 3 8 0 040 350 0 10 2 0 0 980 35 3 6 0 035 300 0 15 2 0 0 980 36 3 4 0 030 200 0 25 2 0 0 980 37 4 0 0 040 400 0 05 2 0 0 950 38 3 8 0 035 350 0 10 2 0 0 950 39 3 6 0 030 300 0 15 2 0 0 950 40 3 4 0 025 200 0 25 2 0 0 950 41 4 0 0 040 400 0 05 2 0 0 950 42 3 8 0 035 350 0 10 2 0 0 950 43 3 6 0 030 300 0 15 2 0 0 950 44 3 4 0 025 200 0 25 2 0 0 950 45 3 8 0 035 400 0 05 3 0 0 995 154 Bay Area Hydrology Model 2013 User Manual March 2014 46 3 6 0 030 350 0 10 3 0 0 995 47 3 4 0 022 300 0 15 3 0 0 995 48 3 2 0 020 200 0 25 3 0 0 995 LZSN Lower Zone Storage Nominal inches INFILT Infiltration inches per hour LSUR Length of surface flow path feet SLSUR Slope of surface flow path feet feet KVARY Variable groundwater recession AGWRC Active Groundwater Recession Constant per day 155 Bay Area Hydrology Model 2013 User Manual March 2014 Table 3 BAHM2013 Alameda San Mateo HSPF Pervious Parameter Values Part II PERLND No INFEXP INFILD DEEPFR BASETP AGWETP 1 2 2 0 02 0 0 2 2 2 0 02 0 0 3 2 2 0 02 0 0 4 2 2 0 02 0 0 5 2 2 0 02 0 0 6 2 2 0 02 0 0 7 2 2 0 02 0 0 8 2 2 0 0
92. 55 0 45 0 40 45 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 46 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 47 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 48 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 169 Bay Area Hydrology Model 2013 User Manual March 2014 This page has been intentionally left blank 170 Bay Area Hydrology Model 2013 User Manual March 2014 APPENDIX B DEFAULT BAHM2013 HSPF PERVIOUS PARAMETER VALUES FOR SANTA CLARA COUNTY The default BAHM2013 HSPF pervious parameter values are found in BAHM2013 file defaultpers uci These pervious parameter values have not changed from the original BAHM values The default BAHM2013 HSPF pervious parameter values for Santa Clara County are based on the HSPF calibration of Ross Creek The default BAHM2013 HSPF pervious parameter values for Alameda and San Mateo counties are listed in Appendix A The HSPF calibrations of Ross Creek and Thompson Creek are documented in the report Clear Creek Solutions 2007 Hydrologic Modeling of the Ross Creek and Thompson Creek Watersheds with the U S EPA Hydrologic Simulation Program FORTRAN HSPF Prepared for Santa Clara Valley Urban Runoff Pollution Prevention Program Any changes in the default BAHM2013 HSPF pervious and impervious parameter values require approval by the local municipal permitting agency unless covered by addit
93. 57 Bay Area Hydrology Model 2013 User Manual March 2014 GRAVEL TRENCH BED ELEMENT BAHM2013 File Edit View Help Summary Report Duk Gravel Trench Bed 1 Outlet 1 Outlet 2 0 0 Gravel Trench Bed Guick Trench Facility Dimension Diagram Facility Dimensions Outlet Structure Data Trench Lenath ft Trench Bottom Width ft SE US aes Riser Diameter g RiserType Flat H Notch Type Layer 1 Thickness ft Orifice Diameter Height Layer 1 porosity 0 1 Number t Layer 2 Thickness ft o sb 4 Layer 2 porosity 0 1 2h 40 Layer 3 Thickness ft abe 4 Layer 3 porosity 0 1 Trench Volume at Riser Head ac ft 000 Commercial Toolbox Show Trench OpenTable H Initial Stage ft Sa Move Elements 4 A 6 24 2013 228PM The gravel trench bed is used to spread and infiltrate runoff but also can have one or more surface outlets represented by an outlet structure with a riser and multiple orifices The user specifies the trench length bottom width total depth bottom slope and left and right side slopes The material layers represent the gravel rock GRAVEL TRENCH BED layers and their design characteristics mw zu D V a thickness and porosity Quick Trench will instantly create a gravel a trench bed with default va
94. 7z irking Steep 10 20 iking Very 2072 v Units of Inches Water Balance Chart Close Units of Acte Ft Nu Basin Total Acres S Load x Deselect Zero Select By co st 15 28 2013 4 PM Click on the Compute LID Base Data button to generate the LID analysis data and summarize the surface runoff interflow groundwater precipitation evaporation and total runoff for all of the basins The results will be shown for each basin in terms of its POC 143 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 File Edit View Help Summary Report Dae e ABS AOS aS 21 8 El t Low Impact Development Scenario Generator xj Ix Bypass for POC LID Scenario Generator Groundwater POC Analyze 1 annual 24 Show Only Selected Surface Interfiow Groundwater Evaporation Total Runoff able Impenous Actes C D Shrub Flat 0 596 B h 15 421 11 053 X iai 5 102 Teepl10 20 eryStee gt 2077 bys Flat 0 5 Surface Percipitation Evaporation Total Runoff Hks Mod 5 10 s St 10 207 S Very 20 Units of Inches Water Balance Chart Close Units of Acre Ft Du Basin Total Acres Deselect Zero Select By 50 _16 28 2013 440PM 0 For Basin 1 50 acres of C D Shrub Flat the distributio
95. Applied to Facility boxes should be checked 61 Bay Area Hydrology Model 2013 User Manual March 2014 CHANNEL ELEMENT BAHM2013 EEK File Edit View Help Summary Report Del te gueumm Or S OBS 2 BK lt 8 channel 1 Mitigated Facility Name Channel 1 Outlet 1 Outlet 2 Outlet 3 Downstream Connection g 0 o Facility Type Use Sections Quick Channel Facility Dimension Diagram CeanandSuagh0030 4 Channel 1 Channel Dimensions General Channel Data Channel Bottom width ft Channel Length ft Manning n coefficient Slope of Channel ft ft Left Side Slope H V Right Side Slope HAV LID Toolbox Commercial Toolbox Show Channel Table OpenTable Move Elements 4 Save xy Load sy x iti Lc FH 8 24 2003 45PM The Channel element allows the user to route runoff from a basin or facility through an open channel to a downstream destination The channel cross section is represented by a trapezoid and is used with Manning s equation to calculate discharge from the channel If a trapezoid does not accurately represent the cross section then the user should represent the channel with an independently calculated SSD Table element or use the Use X Sections option The user inputs channel bottom width channel length channel bottom slope channel left and right
96. Area Hydrology Model 2013 User Manual March 2014 BAHM2013 File Edit View Help Summary Report Washes Os SeaBSalD 2a 3X Basin 1 Pre Project SubbasinName Bsin i 1 Surface Interflow Groundwater Flows To Commercial Toolbox Basin 1 ConnectTo Element Connect to Point Of Compliance Disconnect Element Disconnect POC Find Element Cut Element Copy Element Delete Element Duplicate Predeveloped Save Element Load Element Run Predeveloped Run Mitigated Clear All Steel 10 20 g Area in Basin Available Pervious Acres Show Only Selected Available Impervious Acres A BU rbanFlat 0 5 0 v Roads Flat 0 5 B Urban Mod 5 10 p Roads ModS 10 i Roads Steep 10 2027 B Urban Very S207 o C D Forest Flat 0 5 0 Reads VerjStee 2072 Roof Area C D Forest Mod 5 10 o Driveways Flat 0 5 C D Forest St 10 20 0 T Cr Forest Veg 20 0 Driveways Mod 5 10 Driveways St 10 2072 C D Shrub Flat 0 52 g E D Shrub Mod 5 107z in Driveways Very 20 Sidewalks Flat 0 5 sesioa 5 2 a 054 0 Ei GiassMods10 p je T D Grass Ste 0 20 DO GrassVewo20 0 T 5 0 951047 D T Dms 0 Sidewalks ModS 10 Sidewalks 51020 Sid
97. B30z PakinaSteepito20 O Groundwater D T PaknaVegp2Ug Commercial Toolbox r BFoestMeds10q o 2 Move Elements PerviousTotal 0 E Actes amp impervious Total Actes E p 5 Load x Savery Load Select ANNE gt The project screen also contains the Schematic Editor The Schematic Editor is the grid to the right of the elements This grid is where each element is placed and linked together The grid using the scroll bars on the left and bottom expands as large as needed to contain all of the elements for the project All movement on the grid must be from the top of the grid down The space to the right of the grid will contain the appropriate element information To select and place an element on the grid first left click on the specific element in the Elements menu and then left click on the selected grid square The selected element will appear in the grid square The entire grid can be moved up down left or right using the Move Elements arrow buttons The grid coordinates from one project can be saved Save x y and used for new projects Load x y 38 Bay Area Hydrology Model 2013 User Manual March 2014 The following discussion of the Schematic Editor is divided into Standard Elements LID Elements and Additional Information Standard Elements include Basin Trapezoidal P
98. Bay Area Hydrology Model 2013 User Manual Prepared by Clear Creek Solutions Inc www clearcreeksolutions com Prepared for Alameda Countywide Clean Water Program San Mateo Countywide Water Pollution Prevention Program Santa Clara Valley Urban Runoff Pollution Prevention Program March 2014 To download the Bay Area Hydrology Model 2013 and the electronic version of this user s manual please go to www bayareahydrologymodel org If you have questions about BAHM2013 or its use please contact ACCWP watersheds acpwa org or Arleen Feng 510 670 5575 SCVURPPP SMCWPPP Jill Bicknell jcbicknell 9 eoainc com ii End User License Agreement End User Software License Agreement Agreement By clicking on the Accept Button when installing the Bay Area Hydrology Model 2013 BAHM2013 software or by using the Bay Area Hydrology Model 2013 software following installation you your employer client and associates collectively End User are consenting to be bound by the following terms and conditions If you or User do not desire to be bound by the following conditions click the Decline Button and do not continue the installation process or use of the Bay Area Hydrology Model 2013 software The Bay Area Hydrology Model 2013 software is being provided to End User pursuant to a sublicense of a governmental licensee of Clear Creek Solutions Inc Pursuant to the terms and conditions of this Agreement End User i
99. E E Precipitation Applied to Facility Evaporation Applied to Facility Facility Dimensions EET Facility Bottom Elevation ft feu Depth ft s Riser Height ft p H Riser Diameter n g RiserType Flat H Notch Type Open PondPad Orifice Diameter Height Number ft unos 2 ah 4 LID Toolbox he mes Pond Volume at Riser Head ac ft Show Pond Table OpenTable Commercial Toolbox Initial Stage ft Use Tide Gate NO Move Elements e t AA Grid Scate __200 ft Set Area 0 000 sa ft Save xy Load sy Grid X 00 rt Slope 1 Grid Y 20 SES Hoa 6 24 2013 12 28 The PondPad interface is a grid on which the user can specify the outline of the top of the pond and the pond s side slopes The user selects the line button second from the top on the upper left corner of the PondPad screen Once the line button is turned on the user moves the mouse over the grid to locate the pond s corner points The user does this in a clockwise direction to outline the pond s top perimeter The user can select individual points by clicking on the point button immediately below the line button Once selected any individual point can be moved or repositioned
100. E Z27 PM The infiltration trench dimensions and parameters are Trench Length ft Infiltration trench length Trench Bottom Width ft Infiltration trench width Berm Height ft Height above top of trench at which overflow occurs one foot above riser height 100 Bay Area Hydrology Model 2013 User Manual March 2014 Layer 1 Thickness ft Infiltration trench soil layer depth Layer 1 Porosity Infiltration trench soil porosity Riser Height ft Height of infiltration trench overflow pipe above trench soil surface If a weir is preferred instead of a riser then set the riser height to the weir height and set the riser diameter to the weir length Riser Diameter in Infiltration trench overflow pipe diameter Native Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate If infiltration is used then the user should consult the Infiltration discussion on page 114 The infiltration trench does not include an underdrain If an underdrain is required then use the gravel trench element page 58 instead and set the underdrain height and orifice diameter using the orifice input the orifice height is defined as from the bottom of the lowest layer in the trench BAHM2013 includes automated sizing of the infiltration trench based on a user set target infiltration percentage After the target percentage is set then the use
101. Fail 1511 1429 1393 Pass 1877 1173 673 57 2243 1023 576 56 2609 906 516 56 2975 456 57 Pass 3340 706 414 58 Pass 3706 624 380 60 Pass 4072 569 356 62 4438 527 324 61 4804 488 308 63 Pass 5170 467 292 62 Pass 5536 433 273 63 Pass 5901 410 259 63 Pass 6267 378 241 63 Pass 6633 352 220 62 Pass 6999 326 209 63 Pass 7365 304 199 65 7731 283 189 66 Pass 8097 267 182 68 Pass 8463 250 171 68 Pass 8828 234 162 69 Pass 9194 222 150 67 Pass 9560 205 139 67 Pass 9926 190 132 69 Pass 0292 173 123 71 Pass 0658 165 114 69 Pass 1024 158 108 68 1389 149 100 67 Pass 1755 139 98 70 Pass 2121 125 B9 71 Pass 2487 120 85 70 Pass 2853 115 B2 3219 107 79 73 Pass FLOW cfs 0 15 SE 10E 4 10E 3 10E 2 10E 1 1 10 Percent Time Exceeding Durations Drawdown Hydrograph Analyze datasets 501 POC 1 Predeveloped fov 801 POC 1 Mitigated flow All Datasets Flow Stage Precip 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 EEE a 16 28 2013 253 PM Flow duration at the point of compliance POC 1 is the most common analysis A plot of the flow duration values is shown on the left the flow values on the right The flow duration flow range is from 10 of the 2 year flow frequency value to the 10 year value As shown in th
102. ISA Am f ET iate Facility Name Planter T Outlet 1 Outlet 3 Downstream Connection 18 Facility toune Size PlanterBox Quick Planter Optimize Maximum Planter Box Area ac 1 Underdrain Diameter ft t Orifice Diameter in 0 4 Planter Box Dimensions Planter Length ft Planter Width ft 0 000 Freeboard ft 10 000 KE Effective Total Depth ft x 20 Material Layers for Planter Pro Elements Depth f 00007 1000 Outlet Structure Data Riser Height Above Planter surface t 0 Riser Diameter in 0 Show Planter Table OpenTable H Planter Volume at Riser Head 000 Flow Through Underdrain ac ft n Total Outflow ac ft 0 Percent Through Underdrain The flow through planter dimensions and parameters are 88 Bay Area Hydrology Model 2013 User Manual March 2014 Planter Length ft Length of planter box Planter Bottom Width ft Width of planter box Freeboard Additional storage height above top of riser Effective Total Depth ft Planter height from bottom of planter to top of riser plus freeboard Soil Layer 1 Type Select from Soil Type pulldown menu select BAHM 5 Soil Layer 1 ft Planter soil layer depth NOTE For all bioretention type facilities Attachment L of the Municipal Regional Stormwater Permit MRP s
103. MATION SCRBEBN VER 36 GENERAL PROJECT INFORMATION SCRBEEN eene 37 SCHEMA TNC EDITOR bui asit lat Seabee cus 38 STANDARD 40 BASIN ELEMENT doe AO 41 TRAPEZOIDAL POND ELEMEN 45 VAULT ELEMEN De date ata aaa anes 51 TANK ELEMEN PESE NU IAN PENA THU asd 53 IRREGULAR POND ELEMENT ect 55 GRAVEL TRENCH BED ELEMENT ea e ene duces adu eM 58 SAND FILTER ELEMENT eret pv Pbi aer lane aede tig tees 60 CHANNBE BEBMBNT iet noe va ooa ug ORI SEHE MK RR DEN euin 62 FLOW SPLITTER ELEMENT EUM Ye int 64 TIME SERIES ELEMEN Phro aerea a 66 SSD TABELE ELEMEN P iud at tuc et 67 HIGH GROUNDWATER WETLAND ELEMBENT eene 72 LID ELEMENTS 74 BIORETENTION ELEMENT sc 75 IN GROUND INFILTRATION PLANTER ELEMENT eee 85 FLOW THROUGH PLANTER 88 PERMEABLE PAVEMENT ELEMENT reete eene nnne nette nnne erento ntn 90 DISPERSION wets peat cedendo qutd odes e e dU cuit 93 LATERAL BASIN ELEMENT Pervious eene 95 LATERAL I BASIN ELEMENT Impervious
104. Pond bottom width Effective Depth ft Pond height from pond bottom to top of riser plus at least 0 5 feet extra Left Side Slope H V ratio of horizontal distance to vertical 0 zero for vertical pond sides Bottom Side Slope H V ratio of horizontal distance to vertical 0 zero for vertical pond sides Right Side Slope H V ratio of horizontal distance to vertical 0 zero for vertical pond sides Top Side Slope H V ratio of horizontal distance to vertical 0 zero for vertical pond sides Riser Height ft Height of overflow pipe above pond bottom Riser Diameter in Pond overflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch Notch Width feet width of notch cannot be larger than the riser circumference For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 114 Use Wetted Surface Area sidewalls Yes if infiltration through the pond side slopes is allowed If infiltration is used then the user should consult the Infiltration discussion on page 114 47 Bay Area Hydr
105. R UD Toolbox SS CRS Pond Volume at Riser Head ac ft 672 Show Pond Table OpenTable Initial Stage ft Commercial Toolbox Tide Gate Time Series Demand Determine Outlet With Tide Gate Move Elements E Use Tide Gate vj Y Tide Gate Elevation ft 0 Downstream Connection Save xy Load xy Overflow Elevation ft 0 Iterations n RESI d 6 13 2013 1218PM The final pond dimensions bottom length bottom width effective pond depth and side slopes and outlet structure information riser height riser diameter riser weir type weir notch height and width and orifice diameter and height are shown on the trapezoidal pond screen to the right of the Schematic grid NOTE If Auto Pond selects a bottom orifice diameter smaller than the smallest diameter allowed by the local municipal permitting agency then the user has the option of specifying a minimum allowable bottom orifice diameter even if this size diameter is too large to meet flow duration criteria for this element Additional mitigating BMPs may be required to meet local hydromodification control requirements Please see Appendix D or consult with local municipal permitting agency for more details For manual sizing information see page 47 23 Bay Area Hydrology Model 2013 User Manual March 2014 5 Review analysis BAHM2013 EAR File Edit View Help Summ
106. R APR MAY JUN JUL AUG SEP OCT NOV DEC 1 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 2 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 3 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 4 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 5 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 6 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 7 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 8 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 9 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 10 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 11 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 12 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 13 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 14 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 15 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 16 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 17 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 18 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 19 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 20 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 21 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 22 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 23 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50
107. Table 9 3 see Table 8 0 25 0 35 1 50 0 45 see Table 9 4 see Table 8 0 20 0 35 1 00 0 40 see Table 9 5 see Table 8 0 40 0 30 2 00 0 50 see Table 9 6 see Table 8 0 30 0 30 1 60 0 45 see Table 9 7 see Table 8 0 20 0 30 1 30 0 40 see Table 9 8 see Table 8 0 15 0 30 0 90 0 35 see Table 9 9 see Table 8 0 35 0 25 2 00 0 50 see Table 9 10 see Table 8 0 30 0 25 1 60 0 45 see Table 9 11 see Table 8 0 23 0 25 1 30 0 40 see Table 9 12 see Table 8 0 20 0 25 0 90 0 35 see Table 9 13 see Table 8 0 35 0 25 1 50 0 40 see Table 9 14 see Table 8 0 30 0 25 1 20 0 35 see Table 9 15 see Table 8 0 23 0 25 0 80 0 30 see Table 9 16 see Table 8 0 20 0 25 0 50 0 30 see Table 9 17 see Table 8 0 45 0 35 2 00 0 60 see Table 9 18 see Table 8 0 35 0 35 1 50 0 50 see Table 9 19 see Table 8 0 25 0 35 1 00 0 45 see Table 9 20 see Table 8 0 20 0 35 0 40 0 40 see Table 9 21 see Table 8 0 40 0 30 1 50 0 50 see Table 9 22 see Table 8 0 30 0 30 1 20 0 45 see Table 9 23 see Table 8 0 20 0 30 0 80 0 40 see Table 9 24 see Table 8 0 15 0 30 0 30 0 35 see Table 9 25 see Table 8 0 35 0 25 1 50 0 50 see Table 9 26 see Table 8 0 30 0 25 1 20 0 45 see Table 9 27 see Table 8 0 23 0 25 0 80 0 40 see Table 9 28 see Table 8 0 20 0 25 0 30 0 35 see Table 9 29 see Table 8 0 35 0 25 1 00 0 40 see Table 9 30 see Table 8 0 30 0 25 0 60 0 35 see Table 9 31 see Table 8 0 23 0 25 0 40 0 30 see Table 9 32 see Table 8 0 20 0 25 0 30 0 30 see Table 9 33 see Table 8 0 35 0 35 0 80 0 60 see Table 9 34 see Tab
108. View Help Summary Report Duk x8 CEMR AAI FE Subbasin Name Designate as Bypass for POC Interflow Groundwater Show Only Selected Available Impervious Acres Roads Flat 0 5 Roads Mod 5 10 Roads Steep 10 20 Timestep Project Run Time Roads Ventes 205 Start F Roof Area 1959 10 01 00 00 ENDE 15Minute End 4 Diveways 510 C 30Minue 2000 09 30 24 00 E SCENDE Hourly 5 10 202 C Daily Driveways Very gt 2077 Sidewalks Flat 0 5 Sidewalks Mod 5 10 Sidewakest i0 202 SidewsksVegp20z PakmgFla psz 1 PakingModbinz 1 PakinoSteepito20 fo Parking Vewi2nz 1 Release Timestep Restore Defaults E _ Commercial Toolbox Ir Us FS z DesMM Move Elements PerviousTotal Acres Impervious Total 0 Aces g2 Basin Tota Acres Save xy Lond Deselect Zero Select By s IS 1 f 16 23 2013 The user can change the time step for the HSPF calculations The default time step is hourly NOTE Any change in the default time step requires approval by the local municipal permitting agency or Appendix D Click on the Update button a change has been made To return to the default value click on the Restore Defaults button 150 Bay Area Hydrology Model 2013 User Manual M
109. a flow threshold The user sets the flow threshold value cfs for exit 1 at which flows in excess of the threshold go to exit 2 For example if the flow threshold is set to 5 cfs then all flows less than or equal to 5 cfs go to exit 1 Exit 2 gets only the excess flow above the 5 cfs threshold total flow minus exit 1 flow 65 Bay Area Hydrology Model 2013 User Manual March 2014 TIME SERIES ELEMENT BAHM2013 Eile Edit View Help Summary Report Osh X88 a Os Sama ac en Schematic a Time series 1 Mitigated SCENARIOS Name Pre Project Run Scenario A DEEE 2 Sanjose 22 Calculated Irrigation for Alameda Creek Watershe 1 Predeveloped flow 1 Inflow to POC 1 d POC 1 Mitigated LID Toolbox Commercial Toolbox Move Elements Save xy Load x idolo 6724 2013 4 08 BAHM2013 uses time series of precipitation evaporation and runoff stored in its database HSPF WDM file The user has the option to create or use a time series file external from BAHM2013 in BAHM2013 This may be a time series of flow values created by another HSPF model An example is offsite runoff entering a project site If this offsite runoff is in an existing WDM file and is the same period as BAHM2013 data and the same simulation time step hourly then it can be linked to BAHM2013 model using the Time Series eleme
110. a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch Notch Width feet width of notch cannot be larger than the riser circumference For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 114 Use Wetted Surface Area sidewalls Yes if infiltration through the vault sides is allowed If infiltration is used then the user should consult the Infiltration discussion on page 114 NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor A vault is usually covered and does not receive precipitation on and evaporation from the vault surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should not be checked 52 Bay Area Hydrology Model 2013 User Manual March 2014 TANK ELEMENT BAHM2013 BEE Edit View Help Summary Report zmumeumHeu5Hucooc Fle n Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connection pcm ipitati i il Auto Tank Quick Tank Facility Dimension Diagram Dimensions Outlet Structure Da
111. age Pond Drain Time days Stage feet Percent of Total Run Time Max Stage Drawdown Time dd hh mm ss Flow Frequency Drawdown 1001 Tranezoidal Pond 1 STAGE Mitigated Duration Bounds 001 Minimum 2 Maximum Seasonal Durations mm dd sotte 7777 sege Eug Ri fae 16 13 2013 1223PM Select the pond you want to analyze for drawdown retention time in this example there is only one pond Trapezoidal Pond 1 by clicking on the dataset and highlighting it 28 Bay Area Hydrology Model 2013 User Manual March 2014 Bile Edit View Help Summary Report Duk X858 gEueHEm TAS i le lu S S es zi Analysis Drawdown Analysis ld Trapezoidal Pond 1 STAGE Mitigated Trapezoidal Pond 1 Percent of Total Run Time 8846 5587 7 j Na 7 NA Mas Stage Drawdown Time dd Pond drains in less than 3 days Durations Flow Frequency Drawdown Hydrograph Analyze datasets Duration Bounds 001 Minimum 2 Maximum T Seasonal Durations mm dd Start Date AllDatasets Flow Stage Precip POC1 EndDate 7 16 13 2013 1224PM Click on the Analyze Stage button and the computed pond stages pond water depths are summarized and reported in terms of drain retention time in days For this example a stage depth
112. ain Used Bioretention Bottom Elevatior Bioretention Dimensions Bioretention Length ft 0 000 Total Qutflow ac ft Bioretention Bottom Width ft 10 000 Freeboard ft D Facility Dimension Diagram verroad Flooding It Effective Total Depth ft Piser OutletStuctue 9 Bottom slope of bioretention ft ft 0 0007 Outlet Structure Data Top and Bottom side slope ft ft ooo Riser Height Above bioretention jf 4 Left Side Slope H V 0 000 Riser Diameter in n H Right Side Slope HAV 0 000 RiserType Material Layers for LID Toolbox 1 Lay Layer 3 Depth ft 000 E Soil Layer 1 BAHM 5 Soil Layer 2 GRAVEL Orifice Diameter Height Soil Layer 3 GRAVEL Number in f Commercial Toolbox 1f ao 4 2h do 9 Sho pen Table H pore y Bioretention Volume at Riser Head 000 4r Native Infiltration No Save xy Load xy 0 Y t2 The input information required for the riser outlet structure is Riser Height above Bioretention feet depth of surface ponding before the riser is overtopped Riser Diameter inches diameter of the stand pipe Riser Type Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch Notch Width feet width of notch cannot be
113. airfield Suisun Urban Runoff Management Program FSURMP have also developed HMPs that were adopted by the Water Board however they currently do not use the Bay Area Hydrology Model as the basis for compliance For more information on the MRP see http www waterboards ca gov rwqcb2 water issues programs stornmwater Municipal index shtml Technical memoranda describing these analyses are available in Appendix C of the SCVURPPP HMP Report See www scvurppp org vi supplemented by site design measures that reduce the amount of post project runoff generated at the site Range of Storms to Manage An evaluation was performed of the range of flows that are the most important for stream channel erosion and hydromodification impacts in Santa Clara Valley The evaluation was based on watershed assessments conducted for three subwatersheds in the Valley The lower limit of the range is based on the critical flow Qc in each stream reach that initiates erosion of the stream bed or bank For all three subwatersheds Qc could be approximated as 10 of the 2 year pre development peak flow To partition this allowable flow among contributing land areas an on site project design criteria of 10 of the pre project 2 year peak flow was proposed and later adopted as the allowable low flow from a flow control facility The upper limit on the range of storms was determined by evaluating the contribution of different flow magnitudes to the total
114. al Downstream Connections vio I Precipitation Applied to Facility C Auto Pond QuickPond 2 Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft Riser Height ft Bottom Length ft 8921789446 Riser Diameter in 4 Bottom Width ft 1789446 Riser Type faced en SEA Depth ft Notch Type Feisa Trapezoidal Pom 1 Automatic Pond Adjuster J Bl Predeveloped Umi 210mimn o 10min Mitigated Fast Thorough A Pond Depth incl 1 ft freeboard 4 ft Pond length to width ratio tol Pond Side Slopes 3 to1 BAHM2013 R Bottom Length ESZIzE9aa ft ki Bottom Width 22178924 A Volume at riser head 572 acre ft D Choose Outlet Structure A 1 orifice amp rectangular notch FLOW cfs Percent Time Exceeding 01 si AE E RASA oea 10E1 d 10 Accept pond Close TTT TT TT 6713 2013 120 Auto Pond goes through an iteration process by which it changes the pond dimensions and outlet configuration then instructs BAHM2013 to again compute the resulting Mitigated runoff compare flow durations and decide if it has made the results better or worse This iteration process continues until Auto Pond finally concludes that an optimum solution has been found and the Mitigated flow duration values in red are as close as possible to t
115. alues Part II PERLND No INFEXP INFILD DEEPFR BASETP AGWETP 1 2 2 0 5 0 0 2 2 2 0 5 0 0 3 2 2 0 5 0 0 4 2 2 0 5 0 0 5 2 2 0 5 0 0 6 2 2 0 5 0 0 7 2 2 0 5 0 0 8 2 2 0 5 0 0 9 2 2 0 5 0 0 10 2 2 0 5 0 0 11 2 2 0 5 0 0 12 2 2 0 5 0 0 13 2 2 0 5 0 0 14 2 2 0 5 0 0 15 2 2 0 5 0 0 16 2 2 0 5 0 0 17 2 2 0 5 0 0 18 2 2 0 5 0 0 19 2 2 0 5 0 0 20 2 2 0 5 0 0 21 2 2 0 5 0 0 22 2 2 0 5 0 0 23 2 2 0 5 0 0 24 2 2 0 5 0 0 25 2 2 0 5 0 0 26 2 2 0 5 0 0 27 2 2 0 5 0 0 28 2 2 0 5 0 0 29 2 2 0 5 0 0 30 2 2 0 5 0 0 31 2 2 0 5 0 0 32 2 2 0 5 0 0 33 3 2 0 5 0 0 34 3 2 0 5 0 0 35 3 2 0 5 0 0 36 3 2 0 5 0 0 37 3 2 0 5 0 0 38 3 2 0 5 0 0 39 3 2 0 5 0 0 40 3 2 0 5 0 0 41 3 2 0 5 0 0 42 3 2 0 5 0 0 43 3 2 0 5 0 0 44 3 2 0 5 0 0 45 3 2 0 5 0 0 176 Bay Area Hydrology Model 2013 User Manual March 2014 46 3 2 0 5 0 0 47 3 2 0 5 0 0 48 3 2 0 5 0 0 INFEXP Infiltration Exponent INFILD Infiltration ratio maximum to mean DEEPER Fraction of groundwater to deep aquifer or inactive storage BASETP Base flow from groundwater Evapotranspiration fraction AGWETP Active Groundwater Evapotranspiration fraction 177 Bay Area Hydrology Model 2013 User Manual March 2014 Table 4 BAHM2013 Santa Clara HSPF Pervious Parameter Values
116. amount of erosive work done on the stream bed and banks over a period of time The low flows contribute the most work over time whereas high flows contribute less work because they occur less frequently Approximately 90 95 of the total work on the channel boundary is done by flows between Qc and the pre development 10 year peak flow magnitude Flows greater than the 10 year peak flow contribute less than 10 of the total work Thus the 10 year pre project peak flow was selected as the practical upper limit for controlling erosive flows Hydromodification Management Standard and Design Approach As described in current permits the Hydromodification Management HM standard states that stormwater discharges from applicable new development and redevelopment projects shall not cause an increase in the erosion potential of the receiving stream over the pre project existing condition Increase in runoff flow and volume shall be managed so that post project runoff shall not exceed estimated pre project rates and durations where such increased flow and or volume is likely to cause increased potential for erosion of creek beds and banks silt pollutant generation or other adverse impacts to beneficial uses due to increased erosive force Most of the Bay Area stormwater program permits include performance and applicability criteria to meet this requirement Projects can meet the HM standard by use of on site control measures regional cont
117. apezoidal Pond 1 amp x s qt ft acres acre ft cfs cfs 0 000000 0 918274 0 000000 0 000000 0 000000 All 0 077778 0 922564 0 071588 0 065922 0 000000 0 155556 0 926864 0 143510 0 093228 0 000000 0 233333 0 931174 0 215767 0 114180 0 000000 L 0 311111 0 935495 0 288360 0 131844 0 000000 Trapezoidal Pond 1 0 388889 0 939825 0 361289 0 147406 0 000000 0 466667 0 944165 0 434555 0 161475 0 000000 0 544444 0 948516 0 508160 0 174413 0 000000 0 622222 0 952876 0 582103 0 186455 0 000000 0 700000 0 957246 0 656385 0 197766 0 000000 0 777778 0 961626 0 731008 0 208463 0 000000 0 855556 0 966017 0 805972 0 218638 0 000000 0 933333 0 970417 0 881278 0 228360 0 000000 1 011111 0 974827 0 956926 0 237685 0 000000 1 088889 0 979247 1 032918 0 246657 0 000000 1 166667 0 983678 1 109254 0 255314 0 000000 1 244444 0 988118 1 185935 0 263687 0 000000 LID Toobar 1 322222 0 992568 1 262961 0 271803 0 000000 1 400000 0 997028 1 340335 0 279683 0 000000 1 477778 1 001499 1 418055 0 287347 0 000000 1 555556 1 005979 1 496124 0 294811 0 000000 1 633333 1 010469 1 574541 0 302092 0 000000 1 711111 1 014969 1 653308 0 309201 0 000000 Commercial Toolbox 1 788889 1 019480 1 732426 0 316150 0 000000 1 866667 1 024000 1 811894 0 322950 0 000000 1 944444 1 028530 1 891715 0 329609 0 000000 2 022222 1 033071 1 971888 0 336137 0 000000 Move Elements 2 100000 1 037621 2 052415 0 342540 0 000000 4M 2 177778 1 042181 2 133296 0 348826 0 0000
118. arch 2014 APPENDIX A DEFAULT BAHM2013 HSPF PERVIOUS PARAMETER VALUES FOR ALAMEDA AND SAN MATEO COUNTIES The default BAHM2013 HSPF pervious parameter values are found in BAHM2013 file defaultpers uci These pervious parameter values have not changed from the original BAHM values The default BAHM2013 HSPF pervious parameter values for Alameda and San Mateo counties are based on HSPF calibrations of Castro Valley Creek and Alameda Creek The default BAHM2013 HSPF pervious parameter values for Santa Clara County are based on the HSPF calibration of Ross Creek and Thompson Creek and are listed in Appendix B HSPF calibrations of Castro Valley Creek and Alameda Creek are documented in the report AQUA TERRA Consultants 2006 Hydrologic Modeling of the Castro Valley Creek and Alameda Creek Watersheds with the U S EPA Hydrologic Simulation Program FORTRAN HSPF Prepared for Alameda Countywide Clean Water Program January 20 2006 Any changes in the default BAHM2013 HSPF pervious and impervious parameter values require approval by the local municipal permitting agency unless covered by additional guidance in Appendix D HSPF parameter documentation is found in the document Bicknell B R J C Imhoff J L Kittle Jr Jobes and A S Donigian Jr 2001 Hydrological Simulation Program Fortran User s Manual for Version 12 AQUA TERRA Consultants Mountain View CA 151 Bay Area Hydrology Model 2013 User Manual March
119. ardens with or without underdrains and or infiltration to the native soil e New permeable pavement element to accurately model the movement of water through the pavement and subgrade e Added new SSD Stage Storage Discharge Table element options e Automated sizing options for infiltration facilities Computer Requirements e Windows 2000 XP Vista 7 8 with 200 MB uncompressed hard drive space e Internet access only required for downloading BAHM2013 not required for executing BAHM2013 e Pentium 3 or faster processor desirable e Color monitor desirable Before Starting the Program e Knowledge of the site location and or street address e Knowledge of the actual distribution of existing site soil by category A B or C D e Knowledge of the planned distribution of the proposed development buildings streets sidewalks parking lawn areas overlying the soil categories Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 OVERVIEW The BAHM2013 software architecture and methodology is the same as that developed for the WWHM and uses HSPF as its computational engine Like WWHM BAHM2013 is a tool that generates flow duration curves for the pre and post project condition and then sizes a flow duration control basin or vault and outlet structure to match the pre project curve The software package consists of a user friendly graphical interface with screens for input of pre project and post project conditions an engine
120. art PERLND No MELEV BELV GWDATM PCW PGW UPGW 1 400 0 0 0 35 0 38 0 45 2 400 0 0 0 35 0 38 0 45 3 400 0 0 0 35 0 38 0 45 4 400 0 0 0 35 0 38 0 45 5 400 0 0 0 33 0 35 0 42 6 400 0 0 0 33 0 35 0 42 7 400 0 0 0 33 0 35 0 42 8 400 0 0 0 33 0 35 0 42 9 400 0 0 0 31 0 33 0 40 10 400 0 0 0 31 0 33 0 40 11 400 0 0 0 31 0 33 0 40 12 400 0 0 0 31 0 33 0 40 13 400 0 0 0 30 0 32 0 38 14 400 0 0 0 30 0 32 0 38 15 400 0 0 0 30 0 32 0 38 16 400 0 0 0 30 0 32 0 38 17 400 0 0 0 30 0 32 0 40 18 400 0 0 0 30 0 32 0 40 19 400 0 0 0 30 0 32 0 40 20 400 0 0 0 30 0 32 0 40 21 400 0 0 0 28 0 30 0 37 22 400 0 0 0 28 0 30 0 37 23 400 0 0 0 28 0 30 0 37 24 400 0 0 0 28 0 30 0 37 25 400 0 0 0 26 0 28 0 35 26 400 0 0 0 26 0 28 0 35 27 400 0 0 0 26 0 28 0 35 28 400 0 0 0 26 0 28 0 35 29 400 0 0 0 25 0 27 0 33 30 400 0 0 0 25 0 27 0 33 31 400 0 0 0 25 0 27 0 33 32 400 0 0 0 25 0 27 0 33 33 400 0 0 0 20 0 23 0 28 34 400 0 0 0 20 0 23 0 28 35 400 0 0 0 20 0 23 0 28 36 400 0 0 0 20 0 23 0 28 37 400 0 0 0 18 0 20 0 25 38 400 0 0 0 18 0 20 0 25 39 400 0 0 0 18 0 20 0 25 40 400 0 0 0 18 0 20 0 25 41 400 0 0 0 15 0 17 0 20 42 400 0 0 0 15 0 17 0 20 43 400 0 0 0 15 0 17 0 20 44 400 0 0 0 15 0 17 0 20 45 400 0 0 0 14 0 15 0 18 180 Bay Area Hydrology Model 2013 User Manual March 201
121. ary Report Osh X88 Oum 501 POC 1 Predeveloped The Facility PASSED 801 POC 1 Mitigated flow The Facility PASSED Flow cfs Predev Mit Percentage Pass Fail 1511 1429 1393 97 Pass 1877 1173 673 57 Pass 2243 1023 576 56 2609 906 516 56 2975 797 456 57 Pass 3340 706 414 58 Pass 3706 624 380 60 Pass 4072 569 356 62 Pass 4438 527 324 61 Pass 4804 488 308 63 Pass 5170 467 292 62 Pass 5536 433 273 63 Pass 5901 410 259 63 Pass 6267 378 241 63 Pass 6633 352 220 62 Pass 6999 326 209 63 Pass 7365 304 199 65 Pass 7731 283 189 66 Pass 8097 267 182 68 6463 250 171 68 Pass 8828 234 162 69 Pass 9194 222 150 67 Pass 9560 205 139 67 Pass 9926 190 132 69 Pass 0292 173 123 71 Pass 0658 165 114 69 Pass 1024 158 108 68 Pass 1389 149 100 67 Pass 139 98 70 Pass 125 B9 71 Pass 120 B5 70 Pass 115 82 71 Pass 107 79 73 Pass FLOW cfs 0 115 10E 4 10E 3 10E 2 10 1 1 10 Percent Time Exceeding Durations Drawdown Hydrograph All Datasets Flow 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 i US 1 t By 613 213 1219 The Analysis tool bar button third from the left brings up the Analysis screen where the user can look at the results Each time series dataset is listed in the Analyze Datasets box in the lower left corner To review the flow duration analysis at the point of compliance s
122. bgrade layers and their design characteristics thickness and porosity The subgrade layers Sublayer 1 and Sublayer 2 are available to provide storage prior to discharge through infiltration to the native soil or discharge via an underdrain Quick Pavement will create a permeable pavement feature with default values without checking it for compliancy with flow duration standards The permeable pavement surface area automatically receives rainfall and produces evapotranspiration Due to this model input the permeable pavement surface area should be excluded from the basin element s total surface area NOTE Check with Appendix D or the local municipal permitting agency to find out if ponding on the surface of the pavement is allowed If ponding is not allowed then the ponding depth above pavement value should be set to zero 92 Bay Area Hydrology Model 2013 User Manual March 2014 DISPERSION LID Dispersion practices can include roof runoff dispersion onto adjacent yard area parking lot runoff onto adjacent lawn area and reverse slope sidewalks draining onto adjacent vegetated areas NOTE Specific minimum requirements and standards must be met to allow dispersion see Appendix D and the local municipal permitting agency for details Dispersion is represented in BAHM2013 with lateral flow basin elements BAHM2013 Eile Edit View Help Summary Report Duk Be roo downs serves up to FOO 3f of
123. ch flow increment level comparing the Pre project and Mitigated flow duration results If any of the 100 individual ratio values is greater than allowed by the flow duration criteria then the pond fails to provide an appropriate amount of mitigation and needs to be resized BAHM2013 EAR File Edit View Help Summary Report Oe LECL GEN TAAI ENS le 5 S Schematic l SCENARIOS Faclty Name Facility Type Outlet 1 Outlet 2 Outlet 3 IB Proiect Downstream Connections 2 16 E Ln 7 Mitigated v Precipitation Applied to Facility Auto Pond Quick Pond 2 PEN Applied to Facility Facility Dimension Diagram acility Dimensions ccena Mp MM DM Bottom Lern Ift 7752409 Riser Diameter 8 Bottom Width 0 Riser Type Nothed aus Depth ft Notch Type Rectangular 4 Predeveloped B Mitigated Pond length to width ratio Pond Side Slopes Bottom Length 110775240 Bottom Width 1077524 Volume atriserhead 1 512 FLOW cfs Choose Outlet Structure 1 orifice amp rectangular notch T Progress Move Elements Performing iteration 2 of an estimated 300 Ulo 10E3 10E2 10E B Pond Optimize Pond 2 EA Close Save xy Load sy Percent Time Exceeding a i 83 2003 i207PM Flow duration results are shown in the plots above The vertical axis shows the
124. cility Dimension Diagram Outlet Structure Data 3 Riser Height ft me Riser Diameter n p RiserType Fat H Notch Type Orifice Diameter Height Number in ft rr es 4b ELA ee er Vault Volume at Riser Head ac ft 000 Show Vault Table OpenTable Commercial Toolbox Initial Stage ft Tide Gate Time Series Demand Move Elements Determine Outlet With Tide Gate Use Tide Gate e ys Tide Gate Elevation ft 0 Downstream Connection X Save ay Lead ay Overflow Elevation ft fo Iterations 0 16 24 2013 217 PM_ The storage vault has all of the same characteristics of the trapezoidal pond except that the user does not specify the side slopes by definition they are zero AutoVault and Quick Vault work the same way as Auto Pond and Quick Pond Go to page 47 to find information on how to manually size a vault or other HM facility Vault input information Bottom Length ft Vault bottom length Bottom Width ft Vault bottom width Effective Depth ft Vault height from vault bottom to top of riser plus at least 0 5 feet extra VAULT Riser Height ft Height of overflow pipe above vault bottom Riser Diameter in Vault overflow pipe diameter DEPTH Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro WIDTH 51 Bay Area Hydrology Model 2013 User Manual March 2014 For
125. clicking on the element at which the compliance analysis will be made In the example above the point of compliance analysis will be conducted at the outlet of the trapezoidal pond 119 Bay Area Hydrology Model 2013 User Manual March 2014 Once the point of compliance has been selected File Edit View Help Summary Report the element is modified on the Schematic screen to include a small box with the letter A for e 17 Analysis in the lower right corner This B Schematic identifies the outlet from this element as a point EET of compliance igo The number next to the letter A is the number of the POC POC 1 Move Elements 3 7 Load xy x Emm zm ug _ 120 Bay Area Hydrology Model 2013 User Manual March 2014 CONNECTING ELEMENTS BAHM2013 File Edit View Help Summary Report Subbasin E Designate as Bypass for POC Surface Interflow Groundwater Show Only Selected Area in Basin Available Pervious Acres Commercial Toolbox Connect to Point Of Compliance Disconnect Element Disconnect POC Find Element Cut Element Copy Element Delete Element Duplicate Predeveloped Save Element Load Element C AForestVer gt 20 t Available Impervious Acres Roads Flat 0 5 g 2 A Forest Flat
126. d or 3 diverted to a safe discharge location or other infiltration site if feasible Development of the Bay Area Hydrology Model The concept of designing a flow duration control facility is relatively new and as described above requires the use of a continuous simulation hydrologic model To facilitate this design approach SCVURPPP ACCWP and SMCWPPP decided to jointly fund development of a user friendly automated modeling and flow duration control facility sizing software tool adapted from the Western Washington Hydrology Model WWHM The WWHM was developed in 2001 for the Washington State Department of Ecology to support Ecology s Stormwater Management Manual for Western The matching criterion is as follows the post project flow duration curve may not deviate above the pre project flow duration curve by more than 10 over more than 10 of the length of the curve There are several public domain hydrologic models that can be used for simulating runoff for a continuous rainfall record and sizing flow control facilities Examples are 1 the Army Corps of Engineers Hydrologic Engineering Center Hydrologic Modeling System HEC HMS 2 the Environmental Protection Agency s EPA s Hydrologic Simulation Program Fortran HSPF and 3 the EPA s Stormwater Management Model SWMM viii Washington and assist project proponents in complying with the Western Washington hydromodification control requir
127. dership in creating the WWHM and e The countless municipal staff and consultants who tested BAHM and BAHM2013 and provided comments on earlier versions of the software 10 Washington State Department of Ecology 2001 Stormwater Management Manual for Western Washington Volume III Hydrologic Analysis and Flow Control Design BMPs Publication No 99 13 Olympia WA 11 AQUA TERRA Consultants 2005 Hydrologic Modeling of the Castro Valley Creek and Alameda Creek Watersheds with the U S EPA Hydrologic Simulation Program FORTRAN HSPF Mountain View CA www cleanwaterprogram org This page has been intentionally left blank TABLE OF CONTENTS End User License Asree eoa as ha c cas nts iii FOREWORD 25 te A th sold t e a Bet aac oes es of HydromodifIC allons eeu oerte ida mania anata ooo ecu eate debuit ne tette Technical Analysis of Hydromodification Controls eee vi Hydromodification Management Standard and Design Approach vii Development of the Bay Area Hydrology viii Acknowledgements 24290999 6 detecte Eon ode HA ote ix INTRODUCTION TO BA TIM20 T3 tea oerte RAS 1 BAHM20T 3 OV 3 QUICK START BLEND NAR UHR 5 NEXINGSCISEBNS 2 a a Bl eRe ls pa See 35 MAP INFOR
128. drology Model 2013 User Manual March 2014 Table 7 BAHM2013 Alameda San Mateo HSPF Pervious Parameter Values Part VI PERLND No CEPS SURS UZS IFWS LZS AGWS GWVS 1 0 0 0 01 0 0 5 0 3 0 01 2 0 0 0 01 0 0 5 0 3 0 01 3 0 0 0 01 0 0 5 0 3 0 01 4 0 0 0 01 0 0 5 0 3 0 01 5 0 0 0 01 0 0 5 0 3 0 01 6 0 0 0 01 0 0 5 0 3 0 01 7 0 0 0 01 0 0 5 0 3 0 01 8 0 0 0 01 0 0 5 0 3 0 01 9 0 0 0 01 0 0 5 0 3 0 01 10 0 0 0 01 0 0 5 0 3 0 01 11 0 0 0 01 0 0 5 0 3 0 01 12 0 0 0 01 0 0 5 0 3 0 01 13 0 0 0 01 0 3 5 1 5 0 10 14 0 0 0 01 0 3 5 1 5 0 10 15 0 0 0 01 0 3 5 1 5 0 10 16 0 0 0 01 0 3 5 1 5 0 10 17 0 0 0 01 0 0 5 0 3 0 01 18 0 0 0 01 0 0 5 0 3 0 01 19 0 0 0 01 0 0 5 0 3 0 01 20 0 0 0 01 0 0 5 0 3 0 01 21 0 0 0 01 0 0 5 0 3 0 01 22 0 0 0 01 0 0 5 0 3 0 01 23 0 0 0 01 0 0 5 0 3 0 01 24 0 0 0 01 0 0 5 0 3 0 01 25 0 0 0 01 0 0 5 0 3 0 01 26 0 0 0 01 0 0 5 0 3 0 01 27 0 0 0 01 0 0 5 0 3 0 01 28 0 0 0 01 0 0 5 0 3 0 01 29 0 0 0 01 0 3 5 1 5 0 10 30 0 0 0 01 0 3 5 1 5 0 10 31 0 0 0 01 0 3 5 1 5 0 10 32 0 0 0 01 0 3 5 1 5 0 10 33 0 0 0 01 0 0 5 0 3 0 01 34 0 0 0 01 0 0 5 0 3 0 01 35 0 0 0 01 0 0 5 0 3 0 01 36 0 0 0 01 0 0 5 0 3 0 01 37 0 0 0 01 0 0 5 0 3 0 01 38 0 0 0 01 0 0 5 0 3 0 01 39 0 0 0 01 0 0 5 0 3 0 01 40 0 0 0 01 0 0 5 0 3 0 01 41 0 0 0 01 0 0 5 0 3 0 01 42 0 0 0 01 0 0 5 0 3 0 01 43 0 0 0 01 0
129. e I EmFaexMedpig E D Forest St 10 20 m v Driveways Flat 0 5 1 S D I B venays Modis 102 0 Disconnect POC ener 9m Find Element _ DSe Driveways Very 207 Cut Element 55110205 Jv Sidewalks Fia 0 5 SUE Demi Do shubveybe0 Sidewalks Modi 1077 E ene o 0 Duplicate Predeveloned C D Grass Mod 5 1 0 Sidewalks 520 go jv CO GraseStei0 20 n T ive Element T Load Element C D Grass Ver gt 20 Parking 5102 r Pakaso fad KEREN oMa Run Migated PakingVegip 20 ce Ml Oban a Import Basin Location PerviousT otal Impervious Total SS Actes Basin Total Acres Save xy Load xy 05555 280 Select By 4847 gt f RAVIMA MART AM lt The trapezoidal pond element is placed below the basin element the grid Right click on the basin and select Connect To Element A green line will appear with one end connected to the basin 13 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Ele Edit View Help Summary Report EE ABS OER Ose SORBED OG See Basin 1 Mitigated Subbasin T Designate as Bypass for POC Surface Interflow Groundwater OPre Project Iv Mitigated t
130. e 8 0 25 0 25 0 60 0 35 see Table 9 29 see Table 8 0 40 0 25 0 90 0 40 see Table 9 30 see Table 8 0 35 0 25 0 80 0 35 see Table 9 31 see Table 8 0 28 0 25 0 70 0 30 see Table 9 32 see Table 8 0 25 0 25 0 60 0 30 see Table 9 33 see Table 8 0 40 0 35 1 00 0 80 see Table 9 34 see Table 8 0 35 0 35 0 95 0 50 see Table 9 35 see Table 8 0 25 0 35 0 90 0 45 see Table 9 36 see Table 8 0 20 0 35 0 80 0 40 see Table 9 37 see Table 8 0 35 0 30 0 95 0 70 see Table 9 38 see Table 8 0 30 0 30 0 90 0 45 see Table 9 39 see Table 8 0 25 0 30 0 80 0 40 see Table 9 40 see Table 8 0 20 0 30 0 60 0 35 see Table 9 41 see Table 8 0 35 0 25 0 95 0 70 see Table 9 42 see Table 8 0 30 0 25 0 90 0 45 see Table 9 43 see Table 8 0 25 0 25 0 80 0 40 see Table 9 44 see Table 8 0 20 0 25 0 60 0 35 see Table 9 45 see Table 8 0 30 0 25 0 80 0 40 see Table 9 178 Bay Area Hydrology Model 2013 User Manual March 2014 46 see Table 8 0 28 0 25 0 70 0 35 see Table 9 47 see Table 8 0 25 0 25 0 50 0 30 see Table 9 48 see Table 8 0 20 0 25 0 35 0 30 see Table 9 CEPSC Interception storage inches UZSN Upper Zone Storage Nominal inches NSUR Surface roughness Manning s n INTFW Interflow index IRC Interflow Recession Constant per day LZETP Lower Zone Evapotranspiration fraction 179 Bay Area Hydrology Model 2013 User Manual March 2014 Table 5 BAHM2013 Santa Clara HSPF Pervious Parameter Values P
131. e bottom length and width and volume at riser head will be computed by Auto Pond they cannot be input by the user AutoVault operates the same way as Auto Pond There are some situations where Auto Pond will not work These situations occur when complex routing conditions upstream of the pond make it difficult or impossible for Auto Pond to determine which land use will be contributing runoff to the pond For these situations the pond will have to be manually sized Go to page 47 to find information on how to manually size a pond or other HM facility NOTE If Auto Pond selects a bottom orifice diameter smaller than the smallest diameter allowed by the local municipal permitting agency then the user has the option of specifying a minimum allowable bottom orifice diameter even if this size 116 Bay Area Hydrology Model 2013 User Manual March 2014 diameter is too large to meet flow duration criteria for this element Additional mitigating BMPs may be required to meet local hydromodification control requirements Please see Appendix D or consult with local municipal permitting agency for more details For manual sizing information see page 47 117 Bay Area Hydrology Model 2013 User Manual March 2014 STAGE STORAGE DISCHARGE TABLE BAHM2013 EJES Eile Edit View Help Summary Report Oe X858 gueumemmo5umuocc Bag Tr
132. e flow duration table to the right of the flow duration curves this flow range is divided into approximately 100 levels flow values For each flow level value BAHM2013 counts the number of times that the flow at the Point of Compliance for the Pre project scenario Predev exceeds that specific flow level value It does the same count for the Mitigated scenario flow Dev The total number of counts is the number of simulated hours in the multi year simulation period that the flow exceeds that specific flow level value The Percentage column is the ratio of the Dev count to the Predev count This ratio must be less than or equal to 110 0 for flow levels values between 10 of the 2 year flow value and the 10 year value the upper limit If the percentage value does not exceed this maximum ratio 110 for 10 of the 2 year value to the 10 year value then the Pass Fail column shows a Pass for that flow level If they are exceeded then a Fail is shown One Fail and the facility fails the flow duration criteria The facility overall Pass Fail is listed at the top of the flow duration table 127 Bay Area Hydrology Model 2013 User Manual March 2014 FLOW FREQUENCY BAHM2013 2013 Test 2 Dc PELLE AA i FILEE Mitigated 0 7702 2 3930 3 3402 3 6819 0 1450 0 1416 1 0389 3 4659 2 0323 0 4524 0 1325 a MRI 2 2 3347 4 5999 10 20 30 50 70 80 90 95 99995100 1 2060 0 7155 2 7776 0 1190 Flow
133. e than 10 percent of the time 110 Percent Threshold then the flow duration standard has not been met 2 If more than 10 percent of the flow duration levels exceed the 100 percent threshold then the flow duration standard has not been met The duration criteria in BAHM2013 can be modified by the user if appropriate and the local municipal permitting agency allows see NOTE below The user can conduct the duration analysis using either 1 durations based on Pre project flow frequency or 2 durations based on user defined flow values If using durations based on Pre project flow frequency the percent of the lower limit can be changed from the default of the 2 year flow event to a higher or lower percent value The lower and upper flow frequency limits 2 year and 10 year also can be changed If using durations based on user defined flow values click on that option and input the lower and upper flow values The default pass fail threshold is 110 This value can be changed by the user The duration criteria can be changed for a single point of compliance Click on the Update button once all of the changes have been made To return to the default values click on the Restore Defaults button NOTE Any change s to the default duration criteria must be approved by the appropriate local municipal permitting agency or specified in Appendix D 148 Bay Area Hydrology Model 2013 User Manual March 2014 SCALING FACTORS BAHM201
134. e the option to allow users to automatically size the facility to meet an infiltration target percentage The user can set the target percentage for being filtered infiltrated to 8096 to meet the water quality treatment standard 114 Bay Area Hydrology Model 2013 User Manual March 2014 AUTO POND AUTO VAULT AUTO TANK 7i Ej BAHM2013 File Edit View Help Summary Report Duk EEI LENTASI ECES Ham Schematic X 5 Pond 1 SCENARIOS Type Tiapezoidal Pond Outlet 3 UC Pre Project 7 BA Miioated Precipitation Applied to Facility Auto Pond V Evaporation Applied to Facility Facility Facility Dimensions Facility Bottorn Elevation ft Riser Height ft 0 4 Bottom Lergh Riser Diameter in 0 H Bottom Width ft Riser Type Fiat 4 Effective Depth ft Notch Type Bl Predeveloped BEP Mitigatea lt 2 10 min gt 10 min Thorough Pond Depth incl 1 ft freeboard 4 ft Pond length to width ratio 1 to 1 Pond Side Slopes 3 BotomLeng ft Botomwem Volume at riser head Choose Outlet Structure 1 orifice amp rectangular notch Progress Move Elements 4 59 Create Pond Optimize Pond _Acceptpond Else Save xy Load xy Accent Close J ua a 6 24 2013 321PM
135. eable pavement green roofs rain gardens and vegetated swales All of these approaches reduce stormwater runoff BAHM2013 can be used to determine the magnitude of the reduction from each of these practices and the amount of stormwater detention storage still required to meet HM requirements Bay Area Hydrology Model 2013 User Manual March 2014 QUICK START Quick Start very briefly describes the steps to quickly size a stormwater detention pond using BAHM2013 New users should read the descriptions of the BAHM2013 screens elements and analysis tools before going through the steps described below 1 Select the county in which the project site is located Bay Area Hydrology Model 2013 File Edit View Help Summary Report xia EIEE Ose Seas I c 8 11 2013 19 28 AM Click the down arrow in the box in the upper left corner A list of the counties is shown Scroll down to find the county you want Left click on the county name The county map will then show on the map screen Locate the project site on the map Use the map controls to magnify a portion of the map if needed Select the project site by left clicking on the map location A red square will be placed on the map identifying the project site Bay Area Hydrology Model 2013 User Manual March 2014 16 11 2013 8 28AM The BAHM2013 selects the appropriate rain gage record and precipitation multiplication facto
136. ear peak flow values If necessary the 2 year 5 year 10 year and 25 year values are interpolated from the Tr values generated by Weibull 129 Bay Area Hydrology Model 2013 User Manual March 2014 DRAWDOWN BAHM2013 2013 Test 2 Ele Edit View Help Summary Report Dei guesummews5iusu oc Drawdown Analysis Select analysis for 1001 Trapezoidal Pond 1 STAGE Mitigated Trapezoidal Pond 1 Drain Time days Stage feet Percent of Total Run Time 01769322 8846 7A INA pa Drawdown Time dd hhimra ss Pond drains in less than 3 days Durations Flow Frequency Drawdown Analyze datasets Duration Bounds 001 Minimum Maximum f Seasonal Durations mm dd All Datasets Flow Stage Precip Evap POC1 gees ema 16 29 2013 2 57 PM The drawdown screen is used to compute pond stages water depths These stages summarized and reported in terms of drain retention time in days For this example the maximum stage computed during the entire 35 50 year simulation period is 3 30 feet This maximum stage has a drawdown time of 20 hours 17 minutes 22 seconds Stages can have drain times in excess of 5 days This can occur when a pond has a small bottom orifice If this is not acceptable then the user needs to change the pond outlet configuration manually run the Mitigated scenario and repeat the analyze stage
137. eatment systems with a specified soil mix to remove pollutants Flow control structures are generally detention retention basins or underground vaults or tanks fitted with outlet structures such as weirs and or orifices to control outflow rate and duration Flow control structures can be combined with LID treatment facilities or with flood control facilities The basic approach for design of flow control structures to meet hydromodification requirements involves 1 simulating the runoff from the project site under pre and post project conditions using a continuous simulation hydrologic model with a long term rainfall record 2 generating flow duration curves from the results and 3 designing a flow control facility such that when the post project time series of runoff is routed through the facility the discharge pattern matches the pre project flow duration curve The flow control structure is typically a type of detention facility that diverts and retains a certain portion of the runoff which is essentially the increase in surface runoff volume created between the pre project and post project condition This captured increase in volume must be discharged in one of several ways 1 to the ground via infiltration and or evapotranspiration if vegetation is present in the basin 2 released at a very low rate to the receiving stream at the project critical flow for basin design called Qcp defined as 10 of the pre project 2 year runoff event an
138. ective volume factor is multiplied by the Sublayer 1 storage volume to determine the actual maximum volume available for stormwater storage before the check dam is overtopped and the water in the gravel layer depth Sublayer 1 proceeds to a downstream conveyance facility Pavement Thickness ft Permeable pavement layer depth Pavement Porosity Permeable pavement porosity Layer Thickness ft Subgrade gravel layer depth Layer 1 Porosity Subgrade gravel porosity Layer 2 Thickness ft Sand layer depth if appropriate Layer 2 Porosity Sand porosity Ponding Depth Above Pavement ft Height at which sheet flow occurs on the pavement Underdrain Diameter in Set to zero if there is no underdrain Underdrain Height ft Height of the bottom of the underdrain above the bottom layer Native Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 114 If infiltration is used then the user should consult the Infiltration discussion on page 114 NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor 91 Bay Area Hydrology Model 2013 User Manual March 2014 The permeable pavement layers represent the pavement layer and two su
139. elect the POC 1 tab at the bottom and make sure that both the 501 POC 1 Pre project flow and 801 POC 1 Developed flow are highlighted Click the Run Analysis button if the flow duration analysis is not automatically computed 24 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 a24 Edit View Help Summary Report Duk Se MELLERI SMBS 501 POC 1 Predeveloped 801 POC 1 Mitigated flow FLOW cfs D 15 10 4 10 3 10E2 10E 1 1 10 Percent Time Exceeding Durations Drawdown Hydrograph Analyze datasets OC 1 Predes 801 POC 1 litigated fl AllDatasets Flow Stage Precip Evap POCI 16 13 2013 12 20 PM The flow duration plot for both Pre project and Mitigated flows will be shown along with the specific flow values and number of times Pre project and Mitigated flows exceeded those flow values The Pass Fail on the right indicates whether or not at that flow level the flow control standard criteria were met and the pond passes at that flow level from 10 of the 2 year flow to the 10 year If not a Fail is shown one Fail fails the pond design 25 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Edit View Help Summary Report Duk se Or SB OBS Analysis Durations Flow Frequency Drawdown Hydrograph Analyze datasets 1001 Trapezoidal Pond 1 STAGE Mitigated Duration Bounds 0
140. emblies that are within protective enclosures that screen out large particles and also have 1 2 ft of sump below the orifice to allow for some sediment accumulation While the user can manually set a minimum size for the low flow orifice doing so before running Auto Pond is not recommended as this may impair the program s ability to optimize the pond configuration The following general approach is suggested for designing a pond when there is a small value for the low end of the flow matching range 1 First estimate the minimum pond volume allowing Auto Pond to freely determine the diameter and placement of all orifices 2 Then manually accept all of the pond settings except low flow orifice diameter Set the low flow orifice to the desired minimum size after consulting the local municipal permitting agency 3 Manually run the mitigated scenario as described on page 47 and review the Analysis screen to check if the revised mitigated flow still passes the flow duration criteria for curve matching If so proceed with the pond design using the revised outlet 4 Ifthe revised design shows Fail scoring at one or more flow levels excess flow durations may be reduced somewhat by reducing the depth of the pond which 196 Bay Area Hydrology Model 2013 User Manual March 2014 lowers the head above the orifice SWMMWW recognizes a practical minimum of 3 feet of live storage if pond shallowing is required at the minimum orifice size As an alt
141. ements The original Bay Area Hydrology Model BAHM developed in 2007 was adapted from WWHM Version 3 but has been calibrated to southern San Francisco Bay Area watersheds and enhanced to be able to size other types of control measures and low impact development LID techniques for flow reduction as well This new version of the Bay Area Hydrology Model BAHM2013 includes new tools procedures and methodologies incorporated in WWHMD2012 BAHM2013 is a useful tool in the design process but must be used in conjunction with local design guidance to ensure compliance for specific projects The reader should refer to Appendix D and local stormwater program guidance for additional information and suggestions for using the BAHM Acknowledgements The following individuals and agencies are acknowledged for their contributions to the development of the BAHM2013 and User Manual e Doug Beyerlein Joe Brascher and Gary Maxfield of Clear Creek Solutions Inc for development of WWHM and BAHM2013 and preparation of the BAHM2013 User Manual e Jill Bicknell EOA SCVURPPP Arleen Feng and Jim Scanlin ACCWP Matt Fabry SMCWPPP and Fred Jarvis EOA Inc for their participation in the BAHM Oversight Committee and review of the original BAHM and User Manual e Anthony Donigian AQUA TERRA Consultants for calibration of the Alameda County watersheds and consultation on regional BAHM parameters e Washington State Department of Ecology for its lea
142. eport Parameter Report 8 28 2013 305 PM The Reports tool bar button fourth from the left brings up the Report screen where the user can look at all of the project input and output The project report can be saved or printed The user has the option of producing the report file in a number of different formats Click on Text Report button to generate the report file in WordPad RTF format 133 Bay Area Hydrology Model 2013 User Manual March 2014 Gh Test 2 rtf Microsoft Word E Type question Window Adobe PDF Acrobat Comments Gi BAHM2013 PROJECT REPORT Project Name Test 2 Site Name Site Address City Report Date 6 29 2013 Gage San Jose Data Start 1959 10 01 Data End 2000 09 30 Precip Scale 0 86 Version 2013 06 11 Low Flow Threshold for POC 1 10 Percent of the 2 Year High Flow Threshold for POC 1 10 year PREDEVELOPED LAND USE Name Basin 1 Bypass No GroundWater No Pervious Land Use Acres C D Grass Ste 10 20 10 Pervious Total 10 Impervious Land Use Acres Roads Flat 0 5 lt 3 E 39 lt Scroll down the WordPad screen to see all of the results 134 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 2013 Test 2 File Edit View Help Summary Report Osh X88
143. er Manual March 2014 Table 9 BAHM2013 HSPF Pervious Parameter Values Monthly Lower Zone Evapotranspiration PERLND No JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 2 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 3 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 4 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 5 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 6 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 7 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 8 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 9 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 10 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 11 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 12 0 40 0 40 0 40 0 45 0 50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 13 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 14 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 15 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 16 0 50 0 50 0 50 0 60 0 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 17 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 18 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 19 0 60 0 60 0 60 0 70 0 75 0 75 0 75 0 75 0 75 0 75 0 65 0 60 20 0 60 0 60 0 60 0 7
144. er proportionally to the depth of engineered soil saturation When the engineered soil is fully saturated the underdrain pipe is at full capacity If native infiltration is turned on then native infiltration will start when if 1 Water starts to fill the underdrain if an underdrain is used 2 Water enters the engineered soil if Use Wetted Surface Area sidewalls is set to YES 3 Water saturates the engineered soil layer s to 2 3rds of the total engineered soil depth if there is no underdrain and Wetted Surface Area is set to NO 83 Bay Area Hydrology Model 2013 User Manual March 2014 File Edit View Help Summary Report Dux E pEjueumms s 5iSm Tw I 7 Le Schematic DAG Broretention 1 Mitigated SCENARIOS Facility Name Bioretention 1 Outlet 1 Outlet 2 Outlet 3 L Pre Praject g mnndi E a wk Quick Bioretention Run Scenario Basic Elements i 1 Re Bioretention Dimensions Flow Through Underdrain ac ft Bioretention Length ft 1 Total Outflow act Bioretention Bottom Width ft woo Percent Through Undetdrain Freeboard ft Facility Dimension Diagram verioad Flooding 0 Outlet Structure Data Effective Total Depth ft Riser Outlet Structure Bottom slope of bioretention ft ft Outlet Structure Data Top and Bottom side slope ft ft Riser Height Above bioretention 0 4 Left Side Slope H V 0 000 Riser Diameter D H Right Side Slope HAV 0
145. erate 5 10 27 B Grass Steep 10 20 28 B Grass Very Steep gt 20 29 B Urban Flat 0 5 30 B Urban Moderate 5 10 31 B Urban Steep 10 20 32 B Urban Very Steep gt 20 33 C D Forest Flat 0 596 34 C D Forest Moderate 5 10 35 C D Forest Steep 10 20 36 C D Forest Very Steep gt 20 37 C D Shrub Flat 0 5 38 C D Shrub Moderate 5 10 39 C D Shrub Steep 10 20 40 C D Shrub Very Steep gt 20 41 C D Grass Flat 0 5 42 C D Grass Moderate 5 10 43 C D Grass Steep 10 20 42 Bay Area Hydrology Model 2013 User Manual March 2014 44 C D Grass Very Steep gt 20 45 C D Urban Flat 0 596 46 C D Urban Moderate 5 10 47 C D Urban Steep 10 20 48 C D Urban Very Steep gt 20 The user does not need to know or keep track of the HSPF PERLND number That number is used only for internal tracking purposes in the HSPF UCI file created by BAHM2013 The user inputs the number of acres of appropriate basin land use information Pervious land use information is in the form of soil vegetation and land slope For example A Grass Flat means NRCS soil type A non turf grassland vegetation and flat 0 5 land slope There are three basic soil types A well infiltrating soils B moderate infiltrating soils and C D poor infiltrating soils There are four basic vegetation categories forest native shrub rural vegetation non turf grasslands and urban landscaped vegetation Natural
146. ered soil layer should be gravel A full list of the soil mixtures included in BAHM2013 is shown in Table 1 Table 1 BAHM2013 Soil Mixtures Wilting Ksat Soil Type Point Porosity cm hr A L BPH BAHM 5 0 0700 0 450 1 700 12 70 6 90 1 30 7 90 GRAVEL 0 0050 0 420 10 000 1260 00 0 50 1 19 0 20 Sand 0 0200 0 420 3 000 23 56 6 00 0 69 7 26 Gravel Loamy Sand 0 1000 0 450 3 500 570 97 4 00 2 50 5 00 Coarse sand 0 0520 0 395 3 162 23 56 6 26 2 16 7 26 Humous loamy mcs 0 0600 0 470 2 348 15 00 6 50 1 35 7 50 Light loamy mcs 0 0600 0 394 2 145 10 00 6 50 1 14 7 50 Medium coarse sand mcs 0 0820 0 365 2 959 18 00 6 50 1 96 7 50 Loamy mcs 0 0600 0 301 1 941 9 00 7 00 0 94 8 00 Medium fine sand 0 0970 0 350 2 755 11 00 7 00 1 76 8 00 Fine sand 0 0520 0 364 2 552 10 00 7 30 1 55 8 30 Loamy fine sand 0 0600 0 439 1 738 2 18 7 69 0 74 8 69 Loam 0 0560 0 503 1 479 1 32 10 15 0 48 11 15 Sandy loam 0 0350 0 437 1 445 5 98 7 69 0 55 8 69 Fine sandy loam 0 0560 0 504 1 660 1 10 15 00 0 66 16 00 Clay loam 0 0875 0 445 1 413 0 20 24 89 0 41 25 89 Sandy clay loam 0 0665 0 432 1 318 0 30 27 08 0 32 28 08 Silty clay loam 0 0770 0 475 1 514 0 20 31 56 0 51 32 56 Silty clay 0 0980 0 507 1 318 0 10 33 19 0 32 34 19 Clay 0 0980 0 507 1 318 0 06 33 19 0 32 34 19 Peat 0 0995 0 863 3 050 0 15 39 00 2 05 40 00 Amended 1 5 in hr 0 0850 0 450 1 40
147. erflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch TANK Notch Width feet width of notch cannot be ARCHED larger than the riser circumference wa For more information on riser notch options and HEIGHT orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section 1 7 LENGTH Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 114 Use Wetted Surface Area sidewalls Yes if infiltration through the tank sides is allowed If infiltration is used then the user should consult the Infiltration discussion on page 114 NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor A tank is covered and does not receive precipitation on and evaporation from the tank surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should not be checked 54 Bay Area Hydrology Model 2013 User Manual March 2014 IRREGULAR POND ELEMENT BAHM2013 File Edit View Help Summary Report Duk zueHuemSEeeow5su
148. ernative further mitigation can be applied to the low flow orifice flow by adding an additional infiltration measure downstream This can be sized either approximately by estimating an average excess flow from the orifice or with the help of BAHM2013 by returning to the screen for the Pond characteristics and specifying a different Downstream Connection for the bottom orifice which is then connected to an additional element With this revision to the post project scenario the Point of Compliance for the system would then be located at the downstream end of the additional low flow mitigation Alternative Outlet Configurations BAHM2013 has two default types of outlet configurations multiple orifice or orifice plus weir notch based on a standpipe riser structure detailed in the SMMWW The entire standpipe is usually within a cylindrical enclosure or manhole to exclude trash and larger particles that could clog the outlet The SMMWW notes that orifices can also be placed on a tee section or a vertical baffle within the same type of enclosure An alternative configuration is a flat headwall with orifices and or notches protected by racks or gratings This may be fabricated from a large steel plate similar in construction to the extended detention outlets specified in the Denver Colorado manual referenced below This alternative outlet can be simulated in the BAHM2013 as a very large diameter standpipe where the width of the top notch is equal to the
149. es Riser Height ft Height of infiltration basin pond overflow pipe above basin pond soil surface Riser Diameter in Infiltration basin pond overflow pipe diameter Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Use Wetted Surface Area sidewalls Yes if infiltration through the basin pond side slopes is allowed If infiltration is used then the user should consult the Infiltration discussion on page 114 BAHM2013 includes automated sizing of the infiltration basin pond based on a user set target infiltration percentage After the target percentage is set then the user can click on the Size Infiltration Basin button BAHM2013 will iterate to determine the infiltration basin pond length and width needed to meet the target infiltration percentage NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor An infiltration basin pond receives precipitation on and evaporation from the basin pond surface 103 Bay Area Hydrology Model 2013 User Manual March 2014 GREEN ROOF ELEMENT A green roof is roof covered with vegetation and a growing medium typically an engineered soil mix Green roofs are not always green and are also known as vegetated roofs or eco roofs The advantage of a green roof is its abili
150. es The runoff from the Mitigated scenario is compared with the Pre project scenario runoff to determine compliance with flow duration criteria Below the scenario boxes are the Elements Each element represents a specific feature basin pond etc and is described in more detail in the following section 37 Bay Area Hydrology Model 2013 User Manual March 2014 SCHEMATIC EDITOR BAHM2013 2013 Test 2 Eile Edit View Help Summary Report Ox Same I Ef Basin 1 Pre Project SubbasinName E Surface Interflow Flows Ta E m m Area in Basin Available Pervious Acres DG Show Only Selected Available Impervious Acres zs A Forest Flat 0 572 0 jv Roads Flat 0 5 1 AForest Mod 5 10 D e Roads Mod 5 10 Roads Steep 10 202 AfoexVegozm Roads VerjStee 207 Roof Area T AShrub Mod 5 107z 0 IV Driveways Flat 0 5 117 amp ShubStes10207 N AShrubVery S 207 o M Driveways St 10 20 amp Grass Flat 0 572 0 amp Grass Mod 5 10 2 g Driveways Very gt 2077 1 Sidewalks Flat 0 5 I AGrass Stee 10 207 o AGrass Very 5 gt 20 0 L A Urban Flat 0 5 0 AUrban Mod 5 10 0 A Urban Stee 10 20 0 5 A Urban Very 50202 o Sidewalks Mod 5 10 SidewaksSQiD20z M Sidewalks Vey gt 20 PakngFl 5z 1 I PakingMod
151. es typically require capture and detention of a specified volume of stormwater which then is discharged out at flows that can be safely conveyed by downstream channels without undue risk of flooding Flood control facilities usually are required to drain within 24 hours after the end of the design storm in order to be empty for the next storm event This concern that flood control storage remain available for large events has led flood control agencies to require that any storage volume for water quality not be credited for flood control a feature that is sometimes referred to as dead storage Although many factors affect the drawdown time the suggestions below may help BAHM2013 users in evaluating these other requirements If flow duration control is required for a project site it is recommended that the design process start with by using BAHM2013 to obtain a preliminary design for the flow duration pond vault or tank Then check the performance of the facility for vector control concerns and against flood control design criteria as appropriate The latter is typically based on the concept of a single empirical design storm which does not directly correspond to the flow duration approach using frequency analysis in a long term simulation Vector Control If the 3 day drawdown is seldom or never exceeded over the simulation period then likelihood of mosquito breeding in the facility is very low and the design for the pond vault or tank
152. esting and surface maintenance NOTE Permeable pavement can be used in place of conventional pavement for roadways sidewalks driveways and parking lots Check with Appendix D or the local municipal permitting agency to find out under what conditions permeable pavement is allowed Permeable pavement can be represented by the permeable pavement element in BAHM2013 if the following three conditions are met 1 The infiltration rate of the permeable pavement is greater than the peak rainfall rate 2 The infiltration rate of the permeable pavement is greater than the underlying native soil 3 There is subgrade layer of crushed rock gravel between the permeable pavement and the native soil BAHM2013 DER Eile Edit View Help Summary Report Osh X88 pj summus 2 lei Le Ss LEM Permeable Pavement 1 Mitigated Ed SCENARIOS Facility Name Permeable Pavement 1 Outlet 1 Outlet 3 HC Pre Project Downstream Connection g E 2 Mitigate Facility Type Quick Pavement Facility Dimension Diagram Basic Facility Dimensions Overflow Data Pavement Length ft 0 Ponding Depth Above Pavement ft 0 0 Effective Total Depth ft Bottom slope ft ft 0 Effective Volume Factor Sa Layers for Permeable Pavement Pavement Thickness ft 0 Diameter Height Pavement porosity 0 1 in f Sublayer 1 Thickness ft 07 Underdrain D 4
153. ewsksVemp20z T Parking Mod 5 102 J Parking Steep 10 20 Parking Very 20 Import Basin Location Move Elements Load sy iti Y fms mi 16 13 2013 PerviousTotal Impervious Total Basin Total fo e se Acres Deselect Zero Select By B 110 30 The exit from this basin will be selected as our point of compliance for the Pre project scenario Right click on the basin element and highlight Connect to Point of Compliance the point of compliance is defined as the location at which the runoff from both the Pre project scenario and the Mitigated scenario are compared Point Of Compliance The Point of Compliance screen will be shown for Pre project Basin 1 The POC Point of Compliance outlet has been checked for both surface runoff and interflow Element Basin 1 POC Outlet Select POC ADD shallow subsurface flow These are the two flow Diod components of stormwater runoff Do not check the E groundwater box unless there is observed and documented base flow on the project site Click the Connect button in the low right corner to connect this point of compliance to the Pre project basin Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Ele Edit View Help Summary Report Or SOB 220 2 aoe Subbasin Name asi 1 Surface Interflo
154. f compliance Highlight Connect to Point Of Compliance and click 16 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 Edit View Help Summary Report Duk 7 Facility Type Outlet 2 Outlet 3 Downstream Connections V Precipitation Applied to Facility Auto Pond Quick Pond Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft Riser Heitt D 24 Bottom Length ft Riser Diameter in pg Bottom Width ft RieType Fa H Effective Depth ft Notch Type Left Side Slope H V Bottom Side Slope H V Right Side Slope HAV Top Side Slope Infiltration Orifice Diameter Height Number in ET EM Bers nod of EIS CR Pond Volume at Riser Head ac ft n Show Pond Table OpenTable Initial Stage ft Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft 0 DownsteamConnecion Sw Save xy Loadxy Overflow Elevation ft Iterations EDU Vm RAVIMA 112 The Point of Compliance screen will be shown for the pond The pond has one outlet by default The outflow from the pond will be compared with the Pre project runoff The point of compliance is designated as POC 1 BAHM2013 allows for multiple points of compliance Click on the Connect
155. f compliance maximum of 59 in a single project A point of compliance is defined as the location at which the Pre project and Mitigated flows will be analyzed for compliance with the flow control standard BAHM2013 Bile Edit View Help Summary Report Dc eds lt Trapezoidal Pond 1 Mitigated Facility Name Trapezoid Pondi Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections 07 E Elvis WW Precipitation Applied to Facility Auto Pond Quick Pond Facility Facility Dimension Diagram Paseo acility Dimensions Outlet Structure Data Bottom Elevation ft RierHeight t p Bottom Length f p Riser Diameter in p H Bottom Width ft Riser Type Fiat a Effective Depth ft Notch Type Left Side Slope H V Bottom Side Slope H V Right Side Slope H V Top Side Slope HAV Orifice Diameter Height Infiltration x Number in ft T y dh 4 d Ue i es St OC m Element Trapezoidal Pond 1 Pond Volume at Riser Head ac ft n POC Outlet SelectPOC ADD Show Pond Table OpenTable initial Stage f Ss Tide Gate Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation f DownsteemConnecion m a Loads Overflow Elevation ft D iterations ES eal 16 23 2013 2 40 PM The point of compliance is selected by right
156. f discharge conditions 1 There is no discharge from the subsurface layers except for evapotranspiration This means that there is no underdrain and there is no infiltration into the native soil Which this discharge condition is unlikely we still need to be able to model it 2 There is an underdrain but no native infiltration Discharge from the underdrain is computed based on head conditions for the underdrain The underdrain is configured to have an orifice It is possible for the orifice to be the same diameter as the underdrain With a maximum of three soil layers determining head conditions for the orifice is complicated Each modeled layer must overcome matric head before flow through the underdrain can begin Once matric head is overcome by gravity head for all of the layers then the underdrain begins to flow The flow rate is determined based on the ability of the water to move through the soil layers and by the discharge from the orifice whichever is smaller Head conditions are determined by computing the saturation level of the lowest soil layer first Once the lowest soil layer is saturated and flow begins then the gravity head is considered to be at the saturation level of the lowest soil layer Once the lowest soil layer is saturated completely then the head will include the gravity head from the next soil layer above 201 Bay Area Hydrology Model 2013 User Manual March 2014 until gravity head from all soil layers is inc
157. fico Orifice Diameter in Planter Box Dimensions Planter Length ft Planter Bottom Width ft Freeboard ft Effective Total Depth ft Material Layers for Planter Soil Layer 1 pams Sollayer2 Ji Outlet Structure Data Riser Height Above Planter surface ft p Riser Diameter in lo 4 Native Infiltration Nes 4 Native Infiltration in hr ec 4 Total Volume Through Facility ac t Total Volume Through Riser ac ft Total Volume Infiltrated ac ft Percent Infiltrated Flow Through Underdrain ac ft Percent Through Underdrain Show Planter Table OpenTable H Planter Volume at Riser Head act 000 Depth ft 0 0 0 0 0 0 The in ground infiltration planter dimensions and parameters are 85 Bay Area Hydrology Model 2013 User Manual March 2014 Planter Length ft Length of planter box Planter Bottom Width ft Width of planter box Freeboard Additional storage height above top of riser Effective Total Depth ft Planter height from bottom of planter to top of riser plus freeboard Soil Layer 1 Type Select from Soil Type pulldown menu select BAHM 5 Soil Layer 1 ft Planter soil layer depth NOTE For all bioretention type facilities Attachment L of the Municipal Regional Stormwater Permit MRP specifies the biotreatment soil mix for the top layer see Specification of Soils for Biotreatment or Bioretention Facilities in Attach
158. filter bottom width Effective Depth ft Height from bottom of sand filter to top of riser plus at least 0 5 feet extra Left Side Slope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical sand filter sides Bottom Side Slope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical sand filter sides Right Side Slope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical sand filter sides Top Side Slope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical sand filter sides Riser Height ft Height of sand filter overflow pipe above sand filter surface Riser Diameter in Sand filter overflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch Notch Width feet width of notch cannot be larger than the riser circumference For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section Infiltration Yes infiltration through the filter material Hydraulic Conductivity in hr Filtration rate through the sand filter Filter material depth ft Depth of sand filter material for runoff filtration Sand filter receives precipitation on and evaporation from the sand filter surface The Precipitation Applied to Facility and Evaporation
159. he Pre project flow duration values in blue The user may continue to manually optimize the pond by manually changing pond dimensions and or the outlet structure configuration Manual optimization is explained in more detail on page 47 After making these changes the user should click on the Optimize Pond button to check the results and see if Auto Pond can make further improvements 22 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 EER File Edit View Help Summary Report Doel CAGER LAA E FIRES 219 Schematic Trapezoidal Pond 1 Mitigated SCENARIOS Facility Facility Type Trapezoidal Pond Outlet 1 Outlet 2 Outlet 3 Downstream Connections 0 0 gt V Precipitation Applied to Facility 1 Quick Pond IV Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft xz Riser Height ft 3 Bottom Length ft Riser Diameter in jg Bottom Width ft Riser Type Notched Etfective Depth i Notch Type Rectangular Left Side Slope HA B Notch Height ft 0 7223 H Bottom Side Slope HV 3 Notch Width ft pa H Right Side Slope H V Trapezoidal Pond 1 Top Side Slope op pe 3 Orifice Diameter Height Infiltration H Number Gn 0 1 2 f 4 es R
160. iban 102 5 Parking Ver 2077 Commercial Toolbox s C DUmbanSH1020z 05 EB lt Move Elements PervicusTotal Impervious Total Actes e ys Basin Total Acres pisse ose Deselect Zero Select By 50 x iti Li Y AD 16 13 2013 17 56 AM For the Mitigated land use we have 5 5 acres of C D soil urban vegetation moderate slope 0 5 acres of C D soil urban vegetation steep slope 2 acres of roads flat 1 acre of roof area 1 acre of driveways flat 1 acre of sidewalks flat We will add a trapezoidal pond downstream of the basin The impervious land categories are roads roofs sidewalks parking and driveways All are modeled the same except that steeper slopes have less surface retention storage prior to the start of surface runoff 12 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 File Edit View Help Summary Report Duk SORBED OG I al Basin 1 Mitigated Subbasin 1 Designate as Bypass for POC Surface Interflow Groundwater Flows To _ Area in Basin Show Only Selected Available Pervious Acres Available Impervious Acres 11 B UrbanMod 5 1077 0 jv Roads Flat 0 5 2 i BUrbanStee i0 20 p Roads 5109 o 7 E C D Forest Flati0 5 U Roads VewSteel gt 20 Connect to Pont Of Complanc
161. infiltration trench is similar to the dry well There is no bottom discharge pipe or underdrain Water must infiltrate into the native soil underlying the gravel layer of the planter The native soil must have sufficient infiltration capacity to infiltrate all of the stormwater In BAHM2013 the infiltration trench is Infiltration Trench represented by a specialized application of the gravel trench element available in the LID Toolbox To access the elements in the LID Toolbox menu click on the LID Toolbox bar BAHM2013 a24 Ele Edit View Help Summary Report Duk te zueummHow5uuBuuuo c infilt Trench 1 Mitigated Facility Name IInfilt Trench 1 Outlet 1 Outlet 2 dL Pre Project Downstream Connection g 0 Mitiacted Facility Type Infiltration Trench Maximum Facility Area ac 0 Quick Trench Facility Dimensions Trench Length tt Trench Bottom Width ft Berm Height ft Material Layer for Trench Layer 1 Thickness Layer 1 porosity 0 1 Infiltration Infiltration Rate Total Volume Infiltrated ac ft Total Volume Through Riser ac ft Total Volume Through Facility ac ft Percent Infiltrated Outlet Structure Data Riser Height ft D 4 Riser Diameter in 0 Trench Volume at Riser Head ac ft 000 Show Trench Table OpenTable H Size Infiltration Trench Target 100 H Save xy Load sy 6 I 7 27 7
162. ing and the soil column during non storm periods The routine will satisfy potential evapo transpiration PET demands in the same sequence as implemented in HSPF 1 Water available from vegetation interception storage 2 Water available from surface ponding 3 Water available from the bioretention soil layers top layer first Water will be removed from vegetation interception storage and surface ponding and the bioretention soil layers starting at the top layer down to the rooting depth at the potential rate Water is taken from the soil layers below the rooting depth based on a percentage factor to be determined Without this factor there will be no way to remove water from below the rooting depth once it becomes completely saturated References Blum V S S Israel and S P Larson 2001 Adapting MODFLOW to Simulate Water Movement in the Unsaturated Zone MODFLOW 2001 and Other Modeling Odysseys International Groundwater Modeling Center IGWMC Colorado School of Mines Golden Colorado September 11 14 2001 In MODFLOW 2001 and Other Modeling Odysseys Proceedings pp 60 65 Rossman L A 2009 Modeling Low Impact Development Alternatives with SWMM Presented at CHI International Stormwater and Urban Water Systems Conference Toronto Ontario Canada February 20 2009 206
163. ional guidance in Appendix D HSPF parameter documentation is found in the document Bicknell B R J C Imhoff J L Kittle Jr T H Jobes and A S Donigian Jr 2001 Hydrological Simulation Program Fortran User s Manual for Version 12 AQUA TERRA Consultants Mountain View CA 171 Bay Area Hydrology Model 2013 User Manual March 2014 Table 1 BAHM2013 Santa Clara Pervious Land Types PERLND No Soil Vegetation Surface Slope 1 A Forest Flat 0 596 2 A Forest Moderate 5 10 3 A Forest Steep 10 20 4 A Forest Very Steep gt 20 5 A Shrub Flat 0 596 6 A Shrub Moderate 5 10 7 A Shrub Steep 10 20 8 A Shrub Very Steep gt 20 9 A Grass Flat 0 596 10 A Grass Moderate 5 10 11 A Grass Steep 10 20 12 A Grass Very Steep gt 20 13 A Urban Flat 0 5 14 A Urban Moderate 5 10 15 A Urban Steep 10 20 16 A Urban Very Steep gt 20 17 B Forest Flat 0 596 18 B Forest Moderate 5 10 19 B Forest Steep 10 20 20 B Forest Very Steep gt 20 21 B Shrub Flat 0 596 22 B Shrub Moderate 5 10 23 B Shrub Steep 10 20 24 B Shrub Very Steep gt 20 25 B Grass Flat 0 5 26 B Grass Moderate 5 10 27 B Grass Steep 10 20 28 B Grass Very Steep gt 20 29 B Urban Flat 0 596 30 B Urban Moderate 5 10 31 B Urban Steep 10 20 32 B Urban Very Steep gt 20 33 C D Forest
164. is basin as a point of compliance The number is the POC number e g POC 1 10 Bay Area Hydrology Model 2013 User Manual 3 Set up the Mitigated i e Post Project scenario BAHM2013 Ele Edit View Help SummaryReport DG E X856 Commercial Toolbox Waistline Os Sans Basin 1 Mitigated Subbasin Designate as Bypass for POC Surface Interflow March 2014 Groundwater Flows Area in Basin Available Pervious Acres j arara revo asea _ i AGrass Flat 0 5 T AGrass Mod 5 10 AGrass Stee 10 20 m Show Only Selected Available Impervious M Roads tasa amp 10 r Roads Steep i0 20 7 RoadsVeyseeb Jo Reihe fo ET 2 DB Driveways ModS 10 10 r DEI Diven Veb 1 Acres Sidewalks Mod 5 107 I AGrass Vey S202 Er cm T Sidewalks St 10 20 D A Urban Flat 0 5 0 Alban Mod 5 10 o Sidewalks Very 2072 Parking Flat 0 5 10207 anv B 7 Erem r Parking Mod 5 10 51 10 20 Parking Very 2072 p 3 Move Elements PerviousTotal Ez Acres Impervious Total Actes EHE
165. is shown below Top Vidth ro Vidth Rectangular Notch V Notch 108 Bay Area Hydrology Model 2013 User Manual March 2014 By selecting the appropriate notch type the user is then given the option to enter the appropriate notch type dimensions Riser and orifice equations used in BAHM2013 are provided below Headr the water height over the notch orifice bottom q discharge Riser Head Discharge Head water level above riser q 9 739 Riser Diameter Head 1 5 Orifice Equation q 3 782 Orifice Diameter 2 SQRT Headr Rectangular Notch b NotchWidth 1 0 2 Headr where b gt 0 8 3 33 b Headr 1 5 Sutro Wh Top Width Bottom Width Top Width Notch Height Headr Wd Bottom Width Wh the difference between the bottom and top widths Ql rectangular notch q where Notch Width Wh Q2 rectangular notch q where Notch Width Wd 4 91 02 2 V Notch Notch Bottom height from bottom of riser to bottom of notch Theta Notch Angle a 2 664261 0 0018641 Theta 0 00005761 Theta 2 b 0 48875 0 003843 Theta 0 000092124 Theta 2 0 3392 0 0024318 Theta 0 00004715 Theta 2 YoverH Headr NotchBottom Headr a b Headr c Headr 2 Tan Theta 2 Headr 5 2 These equations are provided from the Washington State Department of Ecology s 2005 Stormwater Management Manual for Western Washingt
166. le 8 0 30 0 35 0 65 0 50 see Table 9 35 see Table 8 0 25 0 35 0 50 0 45 see Table 9 36 see Table 8 0 20 0 35 0 20 0 40 see Table 9 37 see Table 8 0 30 0 30 0 75 0 50 see Table 9 38 see Table 8 0 25 0 30 0 55 0 45 see Table 9 39 see Table 8 0 20 0 30 0 35 0 40 see Table 9 40 see Table 8 0 15 0 30 0 20 0 35 see Table 9 41 see Table 8 0 30 0 25 0 70 0 50 see Table 9 42 see Table 8 0 25 0 25 0 50 0 45 see Table 9 43 see Table 8 0 20 0 25 0 30 0 40 see Table 9 44 see Table 8 0 15 0 25 0 15 0 35 see Table 9 45 see Table 8 0 25 0 25 0 50 0 40 see Table 9 158 Bay Area Hydrology Model 2013 User Manual March 2014 46 see Table 8 0 23 0 25 0 35 0 35 see Table 9 47 see Table 8 0 20 0 25 0 25 0 30 see Table 9 48 see Table 8 0 15 0 25 0 15 0 30 see Table 9 CEPSC Interception storage inches UZSN Upper Zone Storage Nominal inches NSUR Surface roughness Manning s n INTFW Interflow index IRC Interflow Recession Constant per day LZETP Lower Zone Evapotranspiration fraction 159 Bay Area Hydrology Model 2013 User Manual March 2014 Table 5 BAHM2013 Alameda San Mateo HSPF Pervious Parameter Values Part PERLND No MELEV BELV GWDATM PCW PGW UPGW 1 400 0 0 0 35 0 38 0 45 2 400 0 0 0 35 0 38 0 45 3 400 0 0 0 35 0 38 0 45
167. low Values Driveways Mod 5 10z d Driveways St 10 20 Analyze Durations for e to cls Eg TE T Driveways Very 20 r Sidewalks Pass Fail threshold Sidewalks Modi5 10 2 Altering the flow duration criteria will change the mitigation requirements for the Tueks SH selected point of compliance only These changes will impact all duration analysis 27 51 telated to the POC including automatic facility sizing and any flow duration analysis Sidewalks Very 20 ib anis Parking Mod 5 10 Restore Defaults 0 M PakingSteepiio20 7 Cometa Toten temo 177 109 _ o F i i r d Move Elements PerviousTotal Acres 4 Impervious Total D Acres g Basin Total Acres 5 Load i Deselect Zero Select By Go vio Ht 16 29 2013 449 PM Options can be accessed by going to View Options This will bring up the Options screen and the ability to modify the built in default duration criteria for flow duration matching and scaling factors for climate variables 147 Bay Area Hydrology Model 2013 User Manual March 2014 DURATION CRITERIA The flow duration criteria are 1 If the post development flow duration values exceed any of the pre project flow levels between 10 of the two year and 100 of the ten year pre project peak flow values mor
168. luded Gravity head from ponding on the surface is included in the orifice calculations only if all of the intervening soil layers are saturated 3 There is native infiltration but no underdrain Discharge infiltration into the native soil is computed based a user entered infiltration rate in units of inches per hour Specific head conditions are not used in determining infiltration into the native soil Any impact due to head on the infiltration rate is considered to be part of the determination of the native soil infiltration rate Because it is possible to have a maximum of three soil layers each modeled layer must overcome matric head before infiltration to the native soil can begin Once matric head is overcome by gravity head for all modeled layers then infiltration begins at a maximum rate determined either by the ability of the water to move through the soil layers or by the ability of the water to infiltrate into the native soil whichever is limiting 4 There is both an underdrain and native infiltration Underdrain flow and native infiltration are computed as discussed above However there is one other limitation to consider In the case where the flow through the soil layer is less than the sum of the discharge through the underdrain and the native infiltration then the flow through the soil layer becomes the limiting flow and must be divided between the native infiltration and the underdrain This division is done based on the relative
169. lues without checking it for compliancy with flow 5 duration criteria Layer 1 Layer2 Layer3 Bottom Width The gravel trench bed input information Trench Length ft Trench bed length 58 Bay Area Hydrology Model 2013 User Manual March 2014 Trench Bottom Width ft Trench bed bottom width Effective Total Depth ft Height from bottom of trench bed to top of riser plus at least 0 5 feet extra Bottom Slope of Trench ft ft Must be non zero Left Side Slope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical trench bed sides Right Side Slope ft ft ratio of horizontal distance to vertical 0 zero for vertical trench bed sides Infiltration Rate in hr Trench bed gravel or other media infiltration rate Layer 1 Thickness ft Trench top media layer depth Layer Porosity Trench top media porosity Layer 2 Thickness ft Trench middle media layer depth Layer 2 is optional Layer 2 Porosity Trench middle media porosity Layer 3 Thickness ft Trench bottom media layer depth Layer 3 is optional Layer 3 Porosity Trench bottom media porosity Riser Height ft Height of trench overflow pipe above trench surface Riser Diameter in Trench overflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch
170. m The change in runoff characteristics from a watershed caused by changes in land use conditions is called hydrograph modification or simply hydromodification As the total area of impervious surfaces increases in previously undeveloped areas infiltration of rainfall decreases causing more water to run off the surface as overland flow at a faster rate Storms that previously didn t produce runoff under rural conditions can produce erosive flows The increase in the volume of runoff and the length of time that erosive flows occur ultimately intensify sediment transport causing changes in sediment transport characteristics and the hydraulic geometry width depth slope of channels The larger runoff durations and volumes and the intensified erosion of streams can impair the beneficial uses of the stream channels Regulatory Context The California Regional Water Quality Control Board Water Board San Francisco Bay Region requires stormwater programs to address the increases in runoff rate and volume from new and redevelopment projects where those increases could cause increased erosion of receiving streams Starting in 2002 Phase 1 municipal stormwater permits in the San Francisco Bay Area contained requirements to develop and implement hydromodification management plans HMPs and to implement associated management measures Portions of this Foreword were excerpted from Bicknell Beyerlein and Feng The Bay Area Hydrology Model A
171. ment L for more details BAHM 5 contains the appropriate soil values to meet the Attachment L standard The first engineered soil layer should be the BAHM 5 soil mix specified by the Municipal Regional Stormwater Permit Attachment L Soil Layer 2 Type Select from Soil Type pulldown menu usually gravel Soil Layer 2 ft Planter gravel layer depth Underdrain Diameter ft Planter underdrain pipe diameter set to zero if no underdrain is included Orifice Diameter in Planter underdrain pipe orifice diameter set to zero if no underdrain is included Riser Height Above Planter Surface ft Height of planter overflow pipe above planter soil surface Riser Diameter in Planter overflow pipe diameter Native Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate If infiltration is used then the user should consult the Infiltration discussion on page 114 NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor 86 Bay Area Hydrology Model 2013 User Manual March 2014 SUES Os Seek 20 Effective Total Depth Material Layers for Planter Native Infiltration in hr Total Volume Through Facility act Total Volume Through Riser ac ft Total Volume Infiltrated ac ft Percen
172. meter Height Infiltration Ino 4 Number in f 1 Rs y EAE He cod tt 4b Pond Volume at Riser Head ac ft B72 Show Pond Table OpenTable Initial Stage ft Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft 0 Downstream Connection X Ss Overflow Elevation ft p Iterations To exit BAHM2013 click on File in the upper left corner and select Exit Or click on the X in red box in upper right hand corner of the screen 34 ELT Bay Area Hydrology Model 2013 User Manual March 2014 MAIN SCREENS BAHM2013 has six main screens These main screens can be accessed through the buttons shown on the tool bar above or via the View menu The six main screens are Map Information General Project Information Analysis Reports Tools LID Low Impact Development Analysis Each is discussed in more detail in the following sections 35 Bay Area Hydrology Model 2013 User Manual March 2014 MAP INFORMATION SCREEN BAHM2013 2013 Test 2 Bile Edit View Help Summary Report Du FIRR 15 14 2013 12 57 PM The Map Screen contains county information The map is directly linked to the meteorological database that contains precipitation and evaporation data The precipitation gage and precip factor are shown to the right of the map They change depending on the
173. n Wordpad Formatted report with charts in pdf format Report opens in pdf viewer PDF Report aft Repo Commercial Toolbox Original text based report Parameter Report Click on Landuse Report button to generate a listing of the input basin land use data in WordPad RTF format 136 Bay Area Hydrology Model 2013 User Manual March 2014 BAHMI013 2013 Test File Edit View Help Osh X88 gaeumimes5usmiuoosc Trapezoidal Pond 1 Mitigated Facility Name TrepezoidalPond Facility Type Trapezoidal Pond _ Outlet 2 Outlet 3 Downstream Connections ff p g 1 Precipitation Applied to Facility Auto Pond Quick Pond V Evaporation Applied to _ Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft n Riser Height ft a p Boom kenah Diameter fig Bottom Width ft Report New Original text based report Report opens in Wordpad Formatted report with charts in pdf format Report opens in pdf viewer PDF Report v Draft Report Original text based report Landuse Report Commercial Toolbox a Parameter Report st Click on Parameter Report button to generate a listing of the HSPF input parameter values that have been changed from their default values
174. n of the precipitation is Surface runoff 1 147 inches per year Interflow 1 106 inches per year Groundwater 0 928 inches per year Evaporation 11 053 inches per year The sum of the surface runoff interflow groundwater evaporation equals 14 234 inches per year The precipitation at this site equals 15 421 inches per year The difference is the water that goes to deep or inactive groundwater and is not available to the downstream stream system Note that for basins with the Urban land use category that irrigation will increase surface runoff interflow groundwater and evaporation and the total will be greater than the precipitation because of the additional irrigation water To look at the other basins click on the Select POC To arrow and select the basin of interest The LID analysis results can be presented in terms of either inches per year or acre feet per year by checking the appropriate box in the lower right portion of the LID analysis screen 144 Bay Area Hydrology Model 2013 User Manual March 2014 To compare the different scenarios side by side in a graphical format click on the Water Balance Chart button BAHM2013 DES Bile Edit View Help Summary Report Dg 58 Elie Ed ed we B E HE OO Go PERASA t Low inpact Develapment Scenaria Generator e UB Water Balance Chart Basin Total El Load x Deselect Zero Select By _ G0
175. nd stage will be computed and the output flow and stage time series will be made available to the user The number 1 denotes that this is POC 1 18 Bay Area Hydrology Model 2013 User Manual March 2014 4 Sizing the pond BAHM2013 Ele Edit View Help Summary Report Duck Se DARAS Be EIGEN TAS I FICER Outlet 1 Downstream Connections 0 Mitigated v Precipitation Applied to Facility I Evaporation Applied to Facility Facility Dimensions Run Scenario Trapezoidal Pond 1 Automatic Pond Adjuster i i i D 0 1 lt 240min gt 10 mine Bb mii Fast Thorough Pond Depth incl 1 ft freeboard 4j ft Pond length to width ratio tol Pond Side Slopes 3 tol Bottom Length ft Bottom width 1 Volume at riser head acre ft LID Toolbox Choose Outlet Structure 1 orifice amp rectangular notch Progress Create Pond Optimize Pond _Acceptpond ___ Close ond Close Commercial Toolbox Move Elements t A g2 mde cae EHI 0 0 Downstream Connection Save xy Load Overflow Elevation ft 0 Iterations n 83 2003 1203PM A trapezoidal stormwater pond can be sized either manually or automatically using Auto Pond For this example Auto Pond will be used Go to page 47 to find more information about how to
176. nfiguration without checking the pond for compliancy with flow duration criteria Quick Pond is sometimes used to quickly create a scenario and check the model linkages prior to sizing the pond Multiple clicks on the Quick Pond button incrementally increase the pond size The user can change the default name Trapezoidal Pond 1 to another more appropriate name if desired Precipitation and evaporation must be applied to the pond unless the pond is covered The pond bottom elevation can be set to an elevation other than zero if the user wants to use actual elevations All pond stage values are relative to the bottom elevation Negative bottom elevations are not allowed The pond effective depth is the pond height including freeboard above the pond bottom It is not the actual elevation of the top of the pond Pond side slopes are in terms of horizontal distance over vertical A standard 3 1 H V side slope would be given a value of 3 A vertical side slope has a value of 0 The pond bottom is assumed to be flat The pond outlet structure consists of a riser and zero to three orifices The riser has a height typically one foot less than the effective depth and a diameter The riser can have either a flat top or a weir notch cut into the side of the top of the riser The notch can be either rectangular V shaped or a Sutro weir More information on the riser weir shapes and orifices is provided later in this manual After the p
177. nt To link the external time series to BAHM2013 the user clicks on the Choose WDM button and identifies the external WDM file The external WDM s individual time series files are shown in the Time Series Out box The selected input dataset is the time series that will be used by BAHM2013 The user also has the option of modifying and or copying time series files using the options shown in the Functions box These options are add subtract apply factor multiply copy raise to a power select a threshold greater than and select a threshold less than Once a specific option is selected then by clicking on Run Analysis the time series is appropriately modified 66 Bay Area Hydrology Model 2013 User Manual March 2014 SSD TABLE ELEMENT BAHM2013 fe fei Ele Edit View Help Summary Report Oe Se zmeHemSoow5sssNuuoooc 6 SSD Table 1 Mitigated Load File Browse Stage Camputed Add Layer Area Storage Stage ft acres acre ft Not Used Not Used Not Used vs Used no Used LID Toolbox S lt Commercial Toolbox Tide Gate Time Series Demand _ Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft 0 Downstream Connection X Overflow Elevation ft 0 Iterations Save xy Load xy
178. nt of Compliance Connecting Elements 107 Bay Area Hydrology Model 2013 User Manual March 2014 OUTLET STRUCTURE CONFIGURATIONS The trapezoidal pond vault tank irregular pond gravel trench bed and sand filter all use a riser for the outlet structure to control discharge from the facility S TrapezoidalPond 1 Mitigated al Facility Name Downstream Connections Facility Type Trapezoidal Pond Precipitation Applied to Facility Riser Diameter Outlet Structure Riser Height ft H Riser Diameter in o Riser Type Notched Notch Type Rectangular NotchHeioht t o H Notch Width ft p H Facility Dimension Diagra Orifice DiameterHeight Infiltration Number In Ft cfs 1f ab 9 2f Hho Ho fo 40 a Pond Volume at Riser Head acre ft 0 Pond Increment 010 d Show Pond Table Open Table ii gt The riser is a vertical pipe with a height above pond bottom typically one foot less than the effective depth The user specifies the riser height and diameter The riser can have up to three round orifices The bottom orifice is usually located at the bottom of the pond and or above any dead storage in the facility The user can set the diameter and height of each orifice The user specifies the riser type as either flat or notched The weir notch can be either rectangular V notch or a Sutro weir The shape of each type of weir
179. o 59 Save Bi Load ub st The dry well dimensions and parameters Dry Well Length ft Length of well Dry Well Width ft Width of well Reservoir Thickness ft Depth of open water storage 98 Bay Area Hydrology Model 2013 User Manual March 2014 Top Soil Layer Thickness ft Dry well soil layer depth Top Soil Layer Porosity Dry well soil porosity Gravel Sand Layer Thickness ft Dry well gravel layer depth Gravel Sand Layer Porosity Dry well gravel porosity Native Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate If infiltration is used then the user should consult the Infiltration discussion on page 114 BAHM2013 includes automated sizing of the dry well based on a user set target infiltration percentage After the target percentage is set then the user can click on the Size Dry Well button BAHM2013 will iterate to determine the dry well length and width needed to meet the target infiltration percentage NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor Note that the dry well is covered there is no precipitation on or evaporation from the dry well 99 Bay Area Hydrology Model 2013 User Manual March 2014 INFILTRATION TRENCH ELEMENT An
180. o increase with each row It can stay constant or even decrease Discharge cannot be negative Discharge should be based on the outlet structure s physical dimensions and characteristics but BAHM2013 does not check externally generated discharge values Surface area acres is only used if precipitation to and evaporation from the facility are applied To input an externally generated SSD Table first create and save the table outside of BAHM2013 Use the Browse button to locate and load the file into BAHM2013 Save the spreadsheet file as a comma delimited file A text file can also be created if more convenient More information on stage storage discharge tables in general can be found starting page 118 68 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 fe f Edit View Help Summary Report Duk Or SOBs SSD Table 1 Mitigated Flows Precipitation Applied Evaporation Applied Facility Type SSD TABLE Manual Infiltration Load File meer a gt mi 1 Commercial Toolbox Tide Gate Series Demand Determine Outlet With Tide Gate Move Elements f Use Tide Gate 4 Tide Gate Elevation ft Downstream Connection arl B Overflow Elevation ft Iterations ntitial Stage ft Save xy Load sy el 8 E 15 24 2013 416 PM L
181. of 0 77 feet occurred 2 9 of the time and took 1 day on average to drain because of continuing inflows to the pond The pond depth of 1 86 feet occurred 0 646 of the time and took 2 days on average to drain for the same reason The maximum stage computed during the entire 35 50 year simulation period is 3 30 feet This maximum stage has a drawdown time of 20 hours 17 minutes 22 seconds approximately 20 5 hours Stages can have drain times in excess of 5 days This can occur when a pond has a small bottom orifice If this is not acceptable then the user needs to change the pond outlet configuration manually run the Mitigated scenario and repeat the analyze stage computations A situation may occur where it is not possible to have both an acceptable pond drawdown retention time and meet the flow duration criteria NOTE See Appendix D or the local municipal permitting agency for an overview of other requirements that may apply regarding drawdown time and suggestions for addressing situations where it is not possible to meet all drawdown retention time guidelines and also meet the flow duration criteria The user manual assumes that the flow duration criteria take precedence unless the user is instructed otherwise by the local municipal permitting agency 20 Bay Area Hydrology Model 2013 User Manual March 2014 6 Produce report EET zusumsessamu iccsc Quick Pond Facility Dimension Diagram Formatted repo
182. of the sand filter and the filter material depth are also needed to size the sand filter default values are 1 0 inch per hour and 1 5 feet respectively SAND FILTER NOTE When using the sand filter element check with the local municipal permitting agency to determine whether this K treatment measure is allowed and the required treatment standard percent of the ENA total runoff volume treated by the sand FILTER MATERIAL filter EM EFFECTIVE DEPTH 60 Bay Area Hydrology Model 2013 User Manual March 2014 The filter discharge is calculated using the equation Q K I A where is the discharge in cubic feet per second cfs K equals the hydraulic conductivity inches per hour For sand filters K 1 0 in hr Sand is the default medium If another filtration material is used then the design engineer should enter the appropriate K value supported by documentation and approval by the reviewing authority Design of a sand filter requires input of facility dimensions and outlet structure characteristics running the sand filter scenario and then checking the volume calculations to see if the Percent Filtered equals or exceeds the treatment standard percentage If the value is less than the treatment standard percentage then the user should increase the size of the sand filter dimensions and or change the outlet structure The sand filter input information Bottom Length ft Sand filter bottom length Bottom Width ft Sand
183. ology Model 2013 User Manual March 2014 NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor A pond receives precipitation on and evaporation from the pond surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should be checked 48 Bay Area Hydrology Model 2013 User Manual March 2014 circumference length of opening sized for 100 yr flow V A rock linino NTS Figure 3 10 Typical Detention Pond Sections NOTE The detention pond section diagram shows the general configuration used in designing a pond and its outlet structure This diagram is from the 49 Bay Area Hydrology Model 2013 User Manual March 2014 Washington State Department of Ecology s 2005 Stormwater Management Manual for Western Washington Consult with your local municipal permitting agency on specific design requirements for your project site 50 Bay Area Hydrology Model 2013 User Manual March 2014 VAULT ELEMENT BAHM2013 Ele Edit View Help Summary Report Dk EILE M rA i FILER erie See L Schematic X Vault 1 Mitigated SCENARIOS Facility Name Outlet 2 Outlet 3 i Pre Project Downstream Connection 0 0 0 Precipitation Applied to Facilty Auto Vault __Quick Vault E Fixed Width For Auto Vault EE Fa
184. on The outlet designs are shown 109 Bay Area Hydrology Model 2013 User Manual March 2014 below They have been reproduced from Volume III of the Stormwater Management Manual for Western Washington which has more information on the subject Q CA V2ghs CAV2gh CV AW Tp hb distance from hydraulic grade line at the 2 year flow of the outflow pipe to the overflow elevation Figure 3 20 Simple Orifice The diameter of the orifice is calculated from the flow The orifice equation is often useful when expressed as the orifice diameter in inches 36 880 d Jh equation 5 where d orifice diameter inches Q flow cfs h hydraulic head ft 110 Bay Area Hydrology Model 2013 User Manual March 2014 SECTION ms Figure 3 24 Rectangular Sharp Crested Weir Q C L 02H H equation 6 where flow cfs C 7327 0 40 HIP ft H P are as shown above L length ft of the portion of the riser circumference as necessary not to exceed 50 percent of the circumference D inside riser diameter ft Note that this equation accounts for side contractions by subtracting 0 1H from L for each side of the notch weir 111 Bay Area Hydrology Model 2013 User Manual March 2014 The physical configuration of the outlet structure should include protection for the riser and orifices to prevent clogging of the outlet from debris or sediment Various outlet configurations are shown
185. onal Durations mm dd 1000 Trapezoidal Pond 1 ALL OUTLETS Mitigated 1001 Trapezoidal Pond 1 STAGE Mitigated Start Date AllDatasets Flow Stage Precip Evap POC1 EndDate aS The Analysis tool bar button third from the left brings up the Analysis screen where the user can look at the results The Analysis screen allows the user to analyze and compare flow durations flow frequency drawdown times and hydrographs 125 Bay Area Hydrology Model 2013 User Manual March 2014 2013 2013 Test 2 Ele Edit View Help Summary Report Oe X8 ABS S Analysis Drawdown 1 Pan Evap Calabazas Duration Bounds 2 Sanlose GOT Minimum 2 22 Calculated Inigation for Alameda Creek Wetershe ve T Seasonal Durations mm dd Stat Date All Datasets Flow Stage Precip Eva POC1 16 28 2013 2 52 PM The user can analyze all time series datasets or just flow stage precipitation evaporation or point of compliance POC flows by selecting the appropriate tab below the list of the different datasets available for analysis 126 Bay Area Hydrology Model 2013 User Manual March 2014 FLOW DURATION BAHM2013 2013 Test 2 File Edit View Help Summary Report Osh X88 TAEI FICE 501 POC 1 Predeveloped The Facility PASSED 801 POC 1 Mitigated flow ES The Facility PASSED Flow cfs Predev Mit Percentage Pass
186. ond Vault Tank Irregular Pond Gravel Trench Bed Sand Filter Channel Flow Splitter Time Series SSD Table and High Groundwater Wetland elements LID Elements include Bioretention In Ground Planter Flow Through Planter Permeable Pavement Dispersion Lateral Basin Pervious Lateral I Basin Impervious Dry Well Infiltration Trench Infiltration Basin Green Roof and Rainwater Harvesting Additional information is provided on Outlet Structure Configurations Infiltration Auto Pond Stage Storage Discharge Table Point of Compliance and Connecting Elements 39 Bay Area Hydrology Model 2013 User Manual March 2014 STANDARD ELEMENTS The following pages contain information about these standard elements Basin Trapezoidal Pond Vault Tank Irregular Pond Gravel Trench Bed Sand Filter Channel Flow Splitter Time Series SSD Table High Groundwater Wetland 40 Bay Area Hydrology Model 2013 User Manual March 2014 BASIN ELEMENT BAHM2013 2013 Test 2 ES Eile Edit View Help Summary Report Del X858 e Basin 1 Pre Project SubbasinName E Surface Interflow Groundwater Flows Ta E m m Area in Basin Show Only Selected Available Pervious Acres Available Impervious Acres f A Forest Flat 0 5 0 jv 0 5 i AForest Mod 5 10 0 Roads Mod 5 10 1 AForest Verp gt 207 g Roads VeryStee g
187. ond is given dimensions and outlet information the user can view the resulting stage storage discharge table by clicking on the Open Table arrow in the lower right corner of the pond information screen This table hydraulically defines the pond s characteristics The user can use either Auto Pond to size a pond or can manually size a pond Use the following steps for manual sizing a pond using an outlet configuration with one orifice and a riser with rectangular notch this is usually the most efficient design 46 Bay Area Hydrology Model 2013 User Manual March 2014 1 Input a bottom orifice diameter that allows a discharge equal to 10 of the 2 year Pre project flow for a stage equal to 2 3rds the height of the riser This discharge can be checked by reviewing the pond s stage storage discharge table 2 Input a riser rectangular notch height equal to 1 3 of the height of the riser Initially set the riser notch width to 0 1 feet 3 Run Pre project and Mitigated scenarios 4 Goto Analysis screen and check flow duration results 5 If pond passes flow duration criteria then decrease pond dimensions 6 If pond fails flow duration criteria then change in order bottom orifice diameter riser notch width pond dimensions 7 Iterate until there is a good match between Pre project and Mitigated flow duration curves or fatigue sets in Pond input information Bottom Length ft Pond bottom length Bottom Width ft
188. oolbox E D Urban Mod E 10z t IP C D urban SI 10 205 0 Parking eryf 20 Move Elements PerviousT otal 0 E Actes 4 Impervious Total Sa Actes E g2 Save Load sy 30 aja _ 16 13 2013 10 11 Deselect Zero Select By Go To the right of the grid is the land use information associated with the basin element Select the appropriate soil vegetation and land slope for the Pre project scenario Soils are based on NRCS general categories A B C and D for modeling purposes BAHM2013 combines C and D into a single C D Vegetation is based on the native or existing vegetation for the Pre project area and the planned vegetation for the planned development Mitigated scenario Non urban vegetation has been divided into forest shrub and non turf grass and refers to the natural non planted vegetation In contrast the developed landscape will consist of urban vegetation lawns flowers planted shrubs and trees Land slope is divided into flat 0 5 moderate 5 10 steep 10 20 and very steep gt 20 land slopes HSPF parameter values in BAHM2013 have been adjusted for the different soil vegetation and land slope categories For this example we will assume that the Pre project land use is 10 acres of D soil with non turf grass vegetation on a steep slope 10 20 and 1 acre of pre project impervious area on a flat 0 5 slope Bay
189. over Type of vegetation on green roof choices are ground cover shrubs or trees Length of rooftop ft Length of the longest runoff path to reach a roof drain Default input values are automatically included with the element They should be changed to reflect actual roof conditions The green roof surface area automatically receives rainfall and produces evapotranspiration Due to this model input the green roof surface area should be excluded from the basin element s total surface area If the green roof is connected to a downstream element or is selected as a point of compliance the user should make sure that the groundwater runoff is included Unlike the other drainage area elements basin element etc the green roof groundwater always contributes to the total runoff The green roof groundwater has nowhere else to go 105 Bay Area Hydrology Model 2013 User Manual March 2014 RAINWATER HARVESTING Rainwater harvesting involves water collection storage and reuse for residential outdoor use The LID credit is pretty simple the drainage area for which there is 100 capture does not have to be included in the BAHM2013 Mitigated land use scenario 106 Bay Area Hydrology Model 2013 User Manual March 2014 ADDITIONAL INFORMATION The following pages contain additional information about these features Outlet Structure Configurations Infiltration Auto Pond Auto Vault Auto Tank Stage Storage Discharge Table Poi
190. p e amp Grass Flat 0 572 0 I Driveways Very gt 20 T ABesModpiUg 0 AGrass Stee 10 20 g Sidewalks Mod 5 10 5 00 p Sovak L A Urban Flat 0 5 0 Sidewalks Very 20 AUrban Mod 5 102 0 Parking Flat 0 5 fi M amsa D 52 o Parking Steep 10 20 7 r aar E 1 Commercial Toolbox Ir BFoestModE 3Uz __ 0 17 1 Move Elements PerviousT otal as Actes 4 Impervious Total Acies g2 F santaa p 5 4 Load x Savery Lond Select ANNE gt 16 14 2013 2 58PM The project screen contains all of the information about the project site for the two land use scenarios Pre project land use conditions and the Mitigated post project land use conditions To change from one scenario to another check the box in front of the scenario name in the upper left corner of the screen Pre project is defined as the existing conditions prior to the proposed land use development Runoff from the Pre project scenario is used as the target for the Mitigated scenario compliance The model will accept any land use for this scenario Mitigated is defined as the developed land use with mitigation measures as selected by the user Mitigated is used for sizing hydromodification control faciliti
191. pecifies the biotreatment soil mix for the top layer see Specification of Soils for Biotreatment or Bioretention Facilities in Attachment L for more details BAHM 5 contains the appropriate soil values to meet the Attachment L standard The first engineered soil layer should be the BAHM 5 soil mix specified by the Municipal Regional Stormwater Permit Attachment L Soil Layer 2 Type Select from Soil Type pulldown menu usually gravel Soil Layer 2 ft Planter gravel layer depth Underdrain Diameter ft Planter underdrain pipe diameter set to zero if no underdrain is included Orifice Diameter in Planter underdrain pipe orifice diameter set to zero if no underdrain is included Riser Height Above Planter Surface ft Height of planter overflow pipe above planter soil surface Riser Diameter in Planter overflow pipe diameter The only difference between an in ground infiltration planter and a flow through planter is whether or not native infiltration is allowed 89 Bay Area Hydrology Model 2013 User Manual March 2014 PERMEABLE PAVEMENT ELEMENT Permeable pavement LID options include porous asphalt or concrete and grid lattice systems non concrete and paving blocks The use of any of these LID options requires that certain minimum standards and requirements are met related to subgrade geotextile material separation or bottom filter layer base material wearing layer drainage conveyance acceptance t
192. pment of the original BAHM and BAHM2013 were funded by the Alameda Countywide Clean Water Program ACCWP the Santa Clara Valley Urban Runoff Pollution Prevention Program SCVURPPP and the San Mateo Countywide Water Pollution Prevention Program SMCWPPP Original HSPF calibration of Alameda watersheds was conducted by AQUA TERRA Consultants of Mountain View CA HSPF calibration of Santa Clara watersheds was conducted by Clear Creek Solutions Clear Creek Solutions the successor of the AQUA TERRA Washington state offices is responsible for BAHM2013 and the BAHM2013 User Manual This user manual is organized so as to provide the user an example of a standard application using BAHM2013 described in Quick Start followed by descriptions of the different components and options available in BAHM2013 Appendices A through C provide a full list of the HSPF parameter values used in BAHM2013 Appendix D contains additional guidance and recommendations by the stormwater programs that have sponsored the BAHM2013 development Throughout the user manual notes using this font sans serif italic alert the user to actions or design decisions for which guidance must be consulted that is external to the BAHM2013 software either provided in Appendix D of this user manual at the BAHM website or by the local municipal permitting agency Purpose The purpose of BAHM2013 is to size hydromodification management or flow control facilities to mitigate the effects
193. quate for other purposes such as those requiring precise location measurement or description of geographical features or engineering analyses other than those described in the documentation This program and accompanying documentation are provided as is without warranty of any kind The entire risk regarding the performance and results of this program is assumed by End User Clear Creek Solutions Inc and the governmental licensee or sublicensees disclaim all warranties either expressed or implied including but not limited to implied warranties of program and accompanying documentation In no event shall Clear Creek Solutions Inc Applied Marine Sciences Incorporated the Alameda County Flood Control and Water Conservation District EOA Incorporated member agencies of the Alameda Countywide Clean Water Program member agencies of the San Mateo Countywide Water Pollution Prevention Program member agencies of the Santa Clara Valley Urban Runoff Pollution Prevention Program or any other LOU Participants or authorized representatives of LOU Participants be liable for any damages whatsoever including without limitation to damages for loss of business profits loss of business information business interruption and the like arising out of the use of or inability to use this program even if Clear Creek Solutions Inc Applied Marine Sciences Incorporated the Alameda County Flood Control and Water Conservation District EOA Incorporated or any member
194. r Note that for this example the rain gage is San Jose and the precipitation multiplication factor is 0 862 The precipitation multiplication factor is the ratio of the project site mean annual precipitation to that of the nearest precipitation station included in BAHM2013 In the above example a factor of 0 862 indicates that the mean annual precipitation of the project site is 86 2 of the mean annual precipitation of the San Jose station BAHM2013 automatically computes the precipitation multiplication factor based on mean annual precipitation data included in its database Bay Area Hydrology Model 2013 User Manual March 2014 2 Use the tool bar immediately above the map to move to the E Scenario Editor Click on the General Project Information button The General Project Information button will bring up the Schematic Editor BAHM2013 File Edit View Zoom Help The schematic editor screen contains two n 3 t scenarios Pre project and Mitigated ri m ba Schematic t SCENARIOS Set up first the Pre project scenario and then the s Pre Project Mitigated scenario Le Mitigated Check the Pre project scenario box Left click on the Basin element under the Elements heading The Basin element represents the project drainage area It is the upper left element LID Toolbox Select any grid cell preferably near the top of the grid and left click on tha
195. r can click on the Size Infiltration Trench button BAHM2013 will iterate to determine the infiltration trench length and width needed to meet the target infiltration percentage NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor Note that unlike the dry well the infiltration trench receives precipitation on and evaporation from the trench surface 101 Bay Area Hydrology Model 2013 User Manual March 2014 INFILTRATION BASIN ELEMENT An infiltration basin pond allows stormwater to enter the basin pond above ground and then infiltrate through the bottom of the basin pond before exiting through a discharge pipe Water can also infiltrate into the native soil beneath the basin pond For the purpose of flow control the discharge from the pipe should not exceed the pre project discharge from the project site for the flow duration range specified by the local jurisdiction Infiltration Basin Pond In BAHM2013 the infiltration basin pond is represented by a specialized application of the trapezoidal pond element available in the LID Toolbox To access the elements in the LID Toolbox menu click on the LID Toolbox bar Oy BAHM2013 File Edit View Help Summary Report Oe gueHmemSoow5ssisEuao osS e e a S7 Infilt Basin 1 Mitigated Facilit
196. r guidance in Appendix D Different values should only be selected following detailed local soil analysis a thorough understanding of the parameters and algorithms and consultation with the appropriate local municipal permitting agency 183 Bay Area Hydrology Model 2013 User Manual March 2014 Table 7 BAHM2013 Santa Clara HSPF Pervious Parameter Values Part VI PERLND No CEPS SURS UZS IFWS LZS AGWS GWVS 1 0 0 0 01 0 0 5 0 3 0 01 2 0 0 0 01 0 0 5 0 3 0 01 3 0 0 0 01 0 0 5 0 3 0 01 4 0 0 0 01 0 0 5 0 3 0 01 5 0 0 0 01 0 0 5 0 3 0 01 6 0 0 0 01 0 0 5 0 3 0 01 7 0 0 0 01 0 0 5 0 3 0 01 8 0 0 0 01 0 0 5 0 3 0 01 9 0 0 0 01 0 0 5 0 3 0 01 10 0 0 0 01 0 0 5 0 3 0 01 11 0 0 0 01 0 0 5 0 3 0 01 12 0 0 0 01 0 0 5 0 3 0 01 13 0 0 0 01 0 3 5 1 5 0 10 14 0 0 0 01 0 3 5 1 5 0 10 15 0 0 0 01 0 3 5 1 5 0 10 16 0 0 0 01 0 3 5 1 5 0 10 17 0 0 0 01 0 0 5 0 3 0 01 18 0 0 0 01 0 0 5 0 3 0 01 19 0 0 0 01 0 0 5 0 3 0 01 20 0 0 0 01 0 0 5 0 3 0 01 21 0 0 0 01 0 0 5 0 3 0 01 22 0 0 0 01 0 0 5 0 3 0 01 23 0 0 0 01 0 0 5 0 3 0 01 24 0 0 0 01 0 0 5 0 3 0 01 25 0 0 0 01 0 0 5 0 3 0 01 26 0 0 0 01 0 0 5 0 3 0 01 27 0 0 0 01 0 0 5 0 3 0 01 28 0 0 0 01 0 0 5 0 3 0 01 29 0 0 0 01 0 3 5 1 5 0 10 30 0 0 0 01 0 3 5 1 5 0 10 31 0 0 0 01 0 3 5 1 5 0 10 32 0 0 0 01 0 3 5 1 5 0 10 33 0 0 0 01 0 0 5 0 3 0 01 34 0 0 0
197. r movement through the soil column is dependent on soil layer characteristics and saturation rates for different discharge conditions Consider a simple two layered bioretention facility designed with two soil layers with different characteristics As water enters the facility at the top it infiltrates into the soil based on the modified Green Ampt equation Equation 1 The water then moves through the top soil layer at the computed rate determined by Darcy s and Van Genuchten s equations As the soil approaches field capacity 1 gravity head is greater than matric head we can determine when water will begin to infiltrate into the second layer lower layer of the soil column This occurs when the matric head is less than the gravity head in the first layer top layer Since the two layers have different soil characteristics water will move through the two layers at different rates Once both layers have achieved field capacity then the layer that first becomes saturated is determined by which layer is more restrictive This is determined by using Darcy s equation to compute flux for each layer at the current level of saturation The layer with the more restrictive flux is the layer that becomes saturated for that time step The next time step the same comparison is made The rate and location of water discharging from the soil layer is determined by the discharge conditions selected by the user There are four possible combinations o
198. rao 50 min vegetaled flow path splash Hock amp M Ox Bug downs pout extersian NTS splash black Sea MB Schematic S Lateral Basin 1 Mitigated SCENARIOS Lateral Basin 1 Run Scenario Basic Elements Pro Elements LID Toolbox Commercial Toolbox Move Elements 4 ey Save xy Load RES T i Element Name Lateral Area 93 Lateral Basin 1 face _ Intepflow Lateral Impervious Flow Basin Designate as Bypass for H t Exam le Roof Area LAT change 1 6 30 2013 19 34 AM Bay Area Hydrology Model 2013 User Manual March 2014 The impervious lateral basin Lateral I Basin 1 in the above scenario is connected to the pervious lateral basin Lateral Basin 1 All of the runoff generated by impervious roof Lateral I Basin 1 is distributed onto pervious urban Lateral Basin 1 before routing to a stormwater control facility pond vault etc The lateral basin dimensions and parameters to adjust to represent dispersion are Impervious IMPLND type select either road roof sidewalks parking or driveways and the associated slope category all roofs are the same there is no roof slope category Soil PERLND type select one of the 48 different pervious land types based on soil vegetation and slope A and B soils will provide more disper
199. rcial Toolbox Move Elements 4 GE Save xy Load xy RESI 1 TN 4 M 6 14 2013 3 06 The impervious lateral basin is similar to the standard basin except that the surface runoff from the lateral impervious basin goes to another adjacent lateral basin impervious or pervious rather than directly to a conveyance system or stormwater facility By definition the impervious lateral basin contains only impervious land types Pervious area is handled separately with the pervious lateral basin Lateral Basin The user selects the impervious lateral basin land type by checking the appropriate box on the Available Impervious Coverages screen This information is automatically placed in the Impervious IMPLND Type box above Once entered the land type can be changed by clicking on the Change button on the right The user enters the number of acres represented by the lateral impervious basin land type If the lateral impervious basin contains two or more impervious land use types then the user should create a separate lateral I basin for each To model parking lot runoff dispersion onto adjacent lawn connect the Lateral I Basin the parking lot to the Lateral Basin the lawn In the model s calculations surface runoff from the parking lot is added to the surface of the lawn urban vegetation The total runoff will then directed to a stormwater conveyance system by the user 97 Bay Area Hydrology Model 2013 User Manual
200. roject runoff flood frequency is calculated based on annual peak flows 3 the range of flows is selected for the flow duration the default is 10 of the 2 year peak to the 10 year peak 4 this flow range is divided into 100 increments and 5 the number of hourly Pre project flow values that exceed each flow increment level Pre project flow duration are counted to create the flow duration curves and accompanying tabular results Next BAHM2013 computes the post project runoff in the Mitigated scenario and routes the runoff through the pond But before the runoff can be routed through the pond the pond must be given dimensions and an outlet configuration Auto Pond uses a set of rules based on the Pre project and Mitigated scenario land uses to give the pond an initial set of dimensions and an initial outlet orifice diameter and riser the riser is given a default rectangular notch This information allows BAHM2013 to compute a stage storage discharge table for the pond With this initial pond stage storage discharge table BAHM2013 1 routes the hourly post project runoff through the pond for the 35 50 years of record to create to the Mitigated flow time series 2 counts the number of hourly Mitigated flow values that exceed each flow increment level this is the Mitigated flow duration and 20 Bay Area Hydrology Model 2013 User Manual March 2014 3 computes the ratio of Mitigated flow values to Pre project flow values for ea
201. rol measures in stream measures or a combination thereof Applicable projects with on site flow control facilities that are designed to provide flow duration control to the pre project condition are considered to comply with the HM standard Flow duration controls must be designed such that post project stormwater discharge rates and durations match pre project discharge rates and durations from 10 of the pre project 2 year peak flow up to Work is a measure of the erosive hydraulic forces on the stream segment in excess of what the stream bed and bank materials can withstand critical shear stress before sediment movement occurs The requirements apply to development or redevelopment projects that create and or replace 1 acre or more of impervious surface area Consult local stormwater programs for guidance on definition of applicable projects vii the pre project 10 year peak On site flow controls include site design techniques treatment controls that have the added effect of reducing flow normally via infiltration and flow control structures Examples of site design features and flow reducing treatment controls also known as low impact development LID techniques include minimizing impervious surface areas preserving natural areas limiting development especially where native soils have good infiltration characteristics directing roof runoff to landscaped areas and installing bioretention areas landscaped tr
202. rt with charts in pdf format Report opens in pdf viewer PDF Report IV Draft Report Landuse Report Original text based report Original text based report Parameter Report Use Tide Gate Tide Gate Elevation ft Lm Downstream Connection E w Saal OverfiowEtevation t 8 terations SS vil m 16 13 2013 Click on Reports tool bar button fourth from the left to generate project report with all of the project information and results The project report can be generated as either a Microsoft Word file or a PDF file 30 Bay Area Hydrology Model 2013 User Manual March 2014 Ul default rtf Microsoft Word Type question iv i gt BAHM2013 PROJECT REPORT Project Name default Site Name Site Address City Report Date 6 13 2013 Gage San Jose Data Start 1959 10 01 Data End 2000 09 30 Precip Scale 0 86 Version 2013 06 11 Low Flow Threshold for POC 1 10 Percent of the 2 Year High Flow Threshold for POC 1 10 year PREDEVELOPED LAND USE Name Basin 1 Bypass No GroundWater No Pervious Land Use C D Grass Ste 10 20 Pervious Total Acres 10 10 Impervious Land Use Acres Roads Flat 0 5 gamme gt default rtf 14 726 characters an approximate value Scroll down the Report screen to see all of the results
203. ry 20 2006 The HSPF calibrations of Ross Creek and Thompson Creek are documented in the report Clear Creek Solutions 2007 Hydrologic Modeling of the Ross Creek and Thompson Creek Watersheds with the U S EPA Hydrologic Simulation Program FORTRAN HSPF Prepared for Santa Clara Valley Urban Runoff Pollution Prevention Program Any changes in the default BAHM2013 HSPF pervious and impervious parameter values require approval by the local municipal permitting agency unless covered by additional guidance in Appendix D HSPF parameter documentation is found in the document Bicknell B R J C Imhoff J L Kittle Jr T H Jobes and A S Donigian Jr 2001 Hydrological Simulation Program Fortran User s Manual for Version 12 AQUA TERRA Consultants Mountain View CA 191 Bay Area Hydrology Model 2013 User Manual March 2014 Table 1 BAHM2013 Impervious Land Types IMPLND No Surface Slope 1 Roads Flat 0 596 2 Roads Moderate 5 10 3 Roads Steep 10 20 4 Roads Very Steep gt 20 5 Roof Area All 6 Driveways Flat 0 596 7 Driveways Moderate 5 10 8 Driveways Steep 10 20 9 Driveways Very Steep gt 20 10 Sidewalks Flat 0 5 11 Sidewalks Moderate 5 10 12 Sidewalks Steep 10 20 13 Sidewalks Very Steep gt 20 14 Parking Flat 0 596 15 Parking Moderate 5 10 16 Parking Steep 10 20 17 Parking Very Steep gt 20 192 Bay Area Hydrology
204. s permitted to use the Bay Area Hydrology Model 2013 software solely for purposes authorized by participating municipal county or special district member agencies of signatory programs which are organized on a county wide basis for implementation of stormwater discharge permits issued by the California Regional Water Quality Control Board San Francisco Bay Region under the National Pollutant Discharge Elimination System The signatory programs include the Alameda Countywide Clean Water Program ACCWP the Santa Clara Valley Urban Runoff Pollution Prevent Program SCVURPPP and the San Mateo Countywide Water Pollution Prevention Program SMCWPPP each of which signed a Letter of Understanding LOU to jointly fund development of BAHM2013 and are hereinafter referred to collectively as LOU Participants The End User is not permitted to use the Bay Area Hydrology Model 2013 software for any other purpose than as described above End User shall not copy distribute alter or modify the Bay Area Hydrology Model 2013 software The BAHM2013 incorporates data on soils climate and geographical features to support its intended uses of identifying site appropriate modeling parameters incorporating user defined inputs into long term hydro logic simulation models of areas within the jurisdictions of the LOU Participants and assisting design of facilities for flow duration control as described in the accompanying documentation These data may not be ade
205. sMuuosoc Schematic 1 Lj racitiy Name Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections ipitation Applied to Facility e x Outlet Structure Riser Height ft fc y Riser Diameter n p H Riser Type Fa H Notch Type Open PondPad nfiltration NO Orifice Diameter Height Number ft T eos sp Av Rm cm UR TE Pond Volume at Riser Head ac ft Show Pond Table BpenTsie Commercial Toolbox Initial Stage ft Use Tide Gate 4 Move Elements T Sy Wm xy Load xy An irregular pond is any pond with a shape that differs from the rectangular top of a trapezoidal pond An irregular pond has all of the same characteristics of a trapezoidal pond but its shape must be defined by the user The Auto Pond option is not available for an irregular shaped pond Go to page 47 to find information on how to manually size an irregular pond or other HM facility To create the shape of an irregular pond the user clicks on the Open PondPad button This allows the user to access the PondPad interface see below 55 Bay Area Hydrology Model 2013 User Manual March 2014 PondPad Interface BAHM2013 a24 File Edit View Help Summary Report Duk x85 rregular Pond 1 Mingated x Facility Name Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections o
206. sion benefits than C or D soils because of their ability to infiltrate more runoff Lateral Area size of contributing or receiving area acres BAHM2013 File Edit View Help Summary Report Del Ose uoc lei Lan Lents ul Lateral Basin 1 Mitigated SCENARIOS Element Name Lateral Basin 1 I Designate as Bypass far H Surface Interflow Groundwater Pre Proj i Trapezoidal Pond 1 Trapezoidal Pond 1 Ls Lateral Pervious Flow Basin Soil PERLND Type B Urban Flat 0 5 Change Run Scenario Lateral Area Iis s LID Toolbox Commercial Toolbox Move Elements 4 eus Save xy Load xy Kem a 6 30 2013 amp 36AM Dispersion will decrease the total runoff but will not totally eliminate the need for a stormwater control facility A pond can be connected to the discharge from the pervious lateral basin to provide the final required mitigation 94 Bay Area Hydrology Model 2013 User Manual March 2014 LATERAL BASIN ELEMENT Pervious Bay Area Hydrology Model 2013 Eile Edit View Help Summary Report Dg we HELLEM TAS E FICE xfi IS ES oma ateral Ba SCENARIOS Element Name Lateral Basin 1 Designate as Bypass for Runoff Type Surface Interflow Groundwater Downstream Connection g g a 3 Element Type
207. st project runoff through the stormwater facility As with the pre project peak flow values the maximum post project flow value for each water year is selected by the model to compute the developed 2 through 100 year flood frequency The pre project two year peak flow is multiplied by 10 to set the lower limit of the erosive flows in accordance with the current hydromodification management HM performance criteria The pre project 10 year peak flow is the upper limit A comparison of the pre project and post project flow duration curves is conducted for 100 flow levels between the lower limit and the upper limit The model counts the number of 1 BAHM2013 is based on WWHM Version 2012 13 The actual flood frequency calculations are made using the Weibull ranking procedure described in Bulletin 17B United States Water Resources Council 1981 14 In BAHM2013 this low flow limit is a user defined variable to allow flexibility pending potential changes in regulatory requirements Bay Area Hydrology Model 2013 User Manual March 2014 hours that pre project flows exceed each of the flow levels during the entire simulation period The model does the same analysis for the post project mitigated flows Low impact development LID practices have been recognized as opportunities to reduce and or eliminate stormwater runoff at the source before it becomes a problem They include compost amended engineered soils bioretention perm
208. surface flow that typically does not enter a stormwater conveyance system but provides base flow directly to streams and rivers The user can specify where each of these three types of runoff should be directed The default setting is for the surface runoff and interflow to go to the stormwater facility groundwater should not be connected unless there is observed base flow occurring in the drainage basin 41 Bay Area Hydrology Model 2013 User Manual March 2014 Table 1 shows the different pervious land types represented in the Basin element Table 1 BAHM2013 Pervious Land Types PERLND No Soil Vegetation Surface Slope 1 A Forest Flat 0 596 2 A Forest Moderate 5 10 3 A Forest Steep 10 20 4 A Forest Very Steep gt 20 5 A Shrub Flat 0 596 6 A Shrub Moderate 5 10 7 A Shrub Steep 10 20 8 A Shrub Very Steep gt 20 9 Grass Flat 0 5 10 A Grass Moderate 5 10 11 A Grass Steep 10 20 12 A Grass Very Steep gt 20 13 A Urban Flat 0 596 14 A Urban Moderate 5 10 15 A Urban Steep 10 20 16 A Urban Very Steep gt 20 17 B Forest Flat 0 596 18 B Forest Moderate 5 10 19 B Forest Steep 10 20 20 B Forest Very Steep gt 20 21 B Shrub Flat 0 596 22 B Shrub Moderate 5 10 23 B Shrub Steep 10 20 24 B Shrub Very Steep gt 20 25 B Grass Flat 0 5 26 B Grass Mod
209. t depth of engineered soil Note that there can be a maximum of three different engineered soil layers Infiltration to the native soil can be turned on by setting Native Infiltration to YES The parameters for native soil infiltration are Measured Infiltration Rate inches per hour infiltration rate of the native soil Infiltration Reduction Factor between 0 and 1 1 Native soil infiltration rate safety factor see page 114 Use Wetted Surface Area sidewalls YES or NO YES allows infiltration to the native soil through the sidewalls of the bioretention unit otherwise all infiltration is through the bottom only If infiltration is used then the user should consult the Infiltration discussion on page 114 NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor The user has two bioretention surface outlet configuration choices 1 riser outlet structure or 2 vertical orifice overflow 79 Bay Area Hydrology Model 2013 User Manual March 2014 Ele Edit View Help Summary Report Du EX Se AaASHES S ol el a Schematic ia Facility Name SCENARIOS Outlet 1 Outlet 2 Outlet 3 Downstream Connection 0 0 E Facility Type Bioretention Swale l Use simple Bioretention Quick Bioretention Underdr
210. t 20 ame eooo E T AShrub Mod 5 10 o M Driveways Flat 0 5 amp ShrubStee 10 207 0 P Driveways Mod 5 10 T Amevaa p e amp Grass Flat 0 572 0 I Driveways Very gt 20 T AGesModsiog 0 iv Sidewaks Favs I AGrass Stee 10 207 g Sidewalks Mod 5 10 ABressVewSp20 0 S ewaksSQiD20z G M SideuaksVeyp20z AUmanModbTU B AUS 0 PakngModEiUE M AUibanVey Sp20 0 PakinaSteepito20 O BfeewHaps 0 PaWngVegpzU 1 Commercial Toolbox BFoestModS102 17 Move Elements PerviousTotal as Acres amp Impervious Total si Actes E g2 F santaa p 5 Load x Savery Load Select ANNE gt 16 14 2013 258 PM The Basin element represents a drainage area that can any combination of soils vegetation and land uses A basin produces three types of runoff 1 surface runoff 2 interflow and 3 groundwater Surface runoff is defined as the overland flow that quickly reaches a conveyance system Surface runoff mainly comes from impervious surfaces Interflow is shallow subsurface flow produced by pervious land categories and varies based on soil characteristics and how these characteristics are altered by land development practices Groundwater is the sub
211. t Infiltrated Show Planter Table lees Percent Through Underdin Planter Volume at Riser Head act 000 Save Load xy I J BAHM2013 includes automated sizing of the planter box based on a user set target infiltration percentage After the target percentage is set then the user can click on the Size Infiltration Planter button BAHM2013 will iterate to determine the planter length and width needed to meet the target infiltration percentage 87 Bay Area Hydrology Model 2013 User Manual March 2014 FLOW THROUGH PLANTER ELEMENT A flow through planter is similar to the in ground infiltration planter except that water is not allowed to infiltrate into the native soil underlying the gravel layer of the planter As with the in ground planter stormwater enters the planter above ground and then infiltrate through the soil and gravel storage layers before exiting through a discharge pipe Flow through Planter For the purpose of flow control the discharge from the pipe should not exceed the pre project discharge from the project site for the flow duration range specified by the local jurisdiction In BAHM2013 the flow through planter is represented by a specialized application of the bioretention element available in the LID Toolbox To access the elements in the LID Toolbox menu click on the LID Toolbox bar File Edit View Help Summary Report Duk amp amp puedes ossi DRM R
212. t grid The basin will appear in that grid cell enne Toolbox Move Elements 4M Sy Save xy Load Br 1 ly fa Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 DES File Edit View Help Summary Report Doel x88 RISA Schematic TEE Basin 1 Pre Project SCENARIOS gueummdSow5isiEiuu csc SubbasinName Bsni 1 Surface Interflow Groundwater Flows Run Scenario Basic Elements A B Urban Flat0 5 0 Area in Basin Available Pervious Acres Show Only Selected Available Impervious Acres v Roads Flat 0 5 B Urban Mod 5 10 0 r BUrban Stee 10 2077 g Roads Mod 5 10 Roads Steep 10 20 BUrban Ven 5 gt 202 0 C D Forest Flat 0 5 0 Roads VerjStee 207 Boot Area C D Forest Mod 5 10 g Driveways Flat 0 5 C D Forest St 10 20 0 E D Forest Very 20 0 5102 Driveways 510 202 C D Shrub Flat 0 52 0 E D Shrub Mod 5 107z g Driveways Very gt 20 I Sidewalks Flat 0 52 r seso E Eb shubVey gt 202 0 Darassa 0 CDre Mode Ie C D 51 1020 __ 10 T EmBressVegp2o _ 0 Sidewalks Mod 5 10 Sidewakssiin20z O Sidewalks Vey gt 202 PakimgModbiDz 51 1020 1 Colb n Commercial T
213. ta Facility Bottom Elevation ft a Riser Height ft 0 z Riser Diameter in g 4 Riser Type Flat H Notch Type Orifice Diameter Height Number in ft VALDE 4 palo eer pas 5 pc cre Tank Volume at Riser Head ac ft D Show Tank Table OpenTatle Intitial Stace ft a Commercial Toolbox Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Move Elements Tide Gate Elevation DownstreamConnection ES 4 Overflow Elevation ft Iterations Save xy Load sy Bo Lily fa 15 24 2013 2 19 PM A storage tank is a cylinder placed on its side The user specifies the tank s diameter and length Auto Tank and Quick Tank work the same way as Auto Pond and Quick Pond Auto Tank is only available in the Mitigated scenario There is a Quick Tank option that creates a tank but does not check for compliance with the flow duration criteria TANK Tank input information Tank Type Circular or Arched For Circular Diameter ft Tank diameter Length ft Tank length For Arched Height ft Tank height Width ft Tank width at widest point DIAMETER 53 Bay Area Hydrology Model 2013 User Manual March 2014 Length ft Tank length Riser Height ft Height of overflow pipe above tank bottom must be less than tank diameter or height Riser Diameter in Tank ov
214. tant BPH bubbling pressure head cm Sat maximum saturated hydraulic conductivity cm hr VG n Van Genuchten number from literature The user can see the values for any of the soil types by selecting the soil type from the pulldown menu View Edit Soil Types Duplicate Name E 4 Restore Defaults Wilting Porosity K Sat V6 n x L BPH If none of the available soil types represents the engineered soil planned for use on the site then the user can select a new soil type and input the appropriate values into the above input table NOTE For all bioretention type facilities Attachment L of the Municipal Regional Stormwater Permit MRP specifies the biotreatment soil mix for the top layer see Specification of Soils for Biotreatment or Bioretention Facilities in Attachment L for more details BAHM 5 contains the appropriate soil values to meet the Attachment L standard The first engineered soil layer should be the BAHM 5 soil mix specified by the Municipal Regional Stormwater Permit Attachment L J ON Effective Depth BIORETENTION SWALE Bottom Length Pervious Pipe Bay Area Hydrology Model 2013 User Manual March 2014 The second engineered soil layer is an intermediate material that is intended to prevent loss of fine material out of the engineered top layer soil mix into the gravel underlayer layer 3 This layer is optional The third bottom engine
215. the weir Vertical Orifice Elevation inches vertical distance from the top of the engineered soil surface to the bottom of the vertical orifice Width of Over road Flow feet weir street length Over road Flooding ft maximum depth of flow over weir street only required for vertical orifice plus overflow outlet 81 Bay Area Hydrology Model 2013 User Manual March 2014 Diagram of bioretention facility with vertical orifice plus overflow Width of Over road Flow Over road Flooding Freeboard O Vertical Orifice Diameter Vertical Orifice Elevation Effective Total Depth Native Soil Underdrain Native Soil Native Soil File Edit View Help Summary Report Duk X guess ssim oo 7 21161 Bioretention 1 Mitigated Facility Name Bioretention 1 Outlet 1 Outlet 2 Downstream Connection Facility Type F Use simple Bioretention Underdrain Diameter ft Orifice Diameter in Flow Through Underdrain ac ft Total Outflow ac ft Percent Through Underdrain Bioretention Bottom Elevatior Bioretention Dimensions Bioretention Length it 0 000 Bioretention Bottom Width ft 0 000 Freeboard It DO00 Dimension Diagram Overtoad Flooding tt e Data Effective Total Depth ft D Riser Dutlet Structure Bottom slope of bioretention ftt poop Outlet Structure Data Top and Bottom side
216. tion through the channel side slopes is allowed If infiltration is used then the user should consult the Infiltration discussion on page 114 NOTE See Appendix D or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor 63 Bay Area Hydrology Model 2013 User Manual March 2014 P BAHM2013 EJES File Edit View Zoom Help Duk te TAA i FICER 1 SS en ow Splitte gated SCENARIOS Facility Name Flow Splitter 1 Downstream Connection Pre Project Both Exits Primary Exit 1 Secondary Exit 2 Trapezoidal Pond 1 Ehannel 1 Run Scenario Upstream Storage Area Lenath ft 10 Basic Elements Maximum Depth of Ponding ft 10 Primary Exit 1 Structure Secondary Exit 2 Structure Control Structure Control Structure H z Riser Height ft fo 4 Riser Height ft 0 H Flow Splitter 1 Riser Diameter in p H Riser Diameter 0 4 Riser Flat 4 Riser Type Flat d Pro Elements Orifice Diameter Height Orifice Diameter Height LID Toolbox Number in ft in S 2 fo Cee 2 p ado 4 3 n oret ado xps zc Commercial Toolbox Volume at Top of Storage area ac ft 000 Show Splitter Table OpenTable Move re Initial Stage ft De Save xy Load xy x iti 2 Y fia aja RR L
217. to reflect the requirement in the Stormwater Management Manual for Western Washington SMMWW to incorporate a Correction Factor CF to determine long term infiltration rates the inverse of the CF is the Infiltration Reduction Factor in BAHM The SMMWW gives three methods for determining CF 1 a table providing empirical correlations between long term infiltration rates and USDA Soil Textural Classification 2 ASTM gradation testing at full scale infiltration facilities or 3 In situ infiltration tests preferably using a Pilot Infiltration Test specified in an appendix of the SMMWW Application of a CF or safety factor attempts to account for clogging and the reduction in infiltration over time which might apply to the bottom of a flow duration pond or the top layer of a bioretention facility However a safety factor is also used to account for uncertainties in the available estimate of in situ infiltration rates The SMMWW notes that its suggested CF values which range from 2 to 4 represent an average degree of long term facility maintenance TSS reduction through pretreatment and site variability 195 Bay Area Hydrology Model 2013 User Manual March 2014 in the subsurface conditions and that increases or decreases to these factors should be considered for unusual situations Suggested safety factors in other texts and guidance generally range from to 4 Bay Area stormwater permits typically require some form of tracking and
218. ty to store some runoff on the plants surfaces and in the growing medium Evapotranspiration by the plants and growing medium reduces the total runoff Runoff movement through the growing medium slows down the runoff and reduces peak discharge during storm events Y t ras LA ET u HOU V8 support panel thermal insulation vapour control layer structural support A green roof is represented by the BAHM2013 green roof element 104 Bay Area Hydrology Model 2013 User Manual March 2014 BAHM2013 DER Ele Edit View Help Summary Report Dei x38 ASHES Os S aR DO G ele SES SCENARIOS Element Name Green Roof 1 Runoff Type Surface Interflow Groundwater A Downstream Connection 1E 1 LI A Element Type I amp reen Roof eM Iv Mitigated Soil PERLND Green ECO ROOF Run Scenario Green Area ac hj i Depth of Material in 4 Dreen Root 1 Slope of Rooftop ft ft 0 001 Vegetative Cover Ground Cover 1 gLength of Rooftop ft 50 UD Toolbox Commercial Toolbox Move Elements Sae Save xy Load sy RES 0 TI E 6730 2013 11 29AM The dimensions and parameters to adjust to represent a green roof are Green Area ac Size of the green roof Depth of Material in Growing media soil depth Slope of Rooftop ft ft Roof surface slope Vegetative C
219. ual March 2014 BAHM2013 Edit View Help Summary Report Del 1 St Trapezoidal Pond 1 Mitigated L3 is Connect To Element Find Element Cut Element Copy Element Commercial Toolbox Delete Element Duplicate Predeveloped TrapezoidalPond 1 zmnenHmemsowvossusmNuoosc Facility Name Trapezoidal Pond 1 Facility Type Trapezoidal Pond Outlet 1 Outlet 2 Outlet 3 Downstream Connections v Precipitati ility Auto Pond Quick Pond Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft Riser Height ft o 4 Bottom Length ft Riser Diameter fin n H Bottom Width f nieTwe Effective Depth ft Notch Type 0 pr Left Side Slope H V Bottom Side Slope H V a Right Side Slope H V a Side Slope Orifice Diameter Height o Number in f Pond Volume at Riser Head ac ft n Show Pond Table OpenTable Initial Stage ft Save Element Load Element Run Predeveloped Run Mitigated Clear All Save xy Load xy depart Basin Location Y BC alm Gate Series Demand termine Outlet With Tide Gate Use Tide Gate le Gate Elevation ft fo Downstream Connection erflow Elevation ft 0 Iterations Ip x RAVIMA 149 1 Right click on the trapezoidal pond element to connect the pond s outlet to the point o
220. verification for treatment and hydromodification facilities In addition designers should not be overly conservative in selecting a very high safety factor since this might lead to over controlled lower post project flows and an increase risk of causing impacts from deposition or sedimentation in the receiving channels In the absence of other guidance it is suggested that the BAHM2013 Infiltration Reduction Factor the inverse of the safety factor not be less than 0 25 or greater than 0 5 Note Bay Area stormwater programs also restrict the use of infiltration for treatment purposes in certain conditions since the flow duration facilities are also performing some treatment designers should refer to the C 3 guidance on treatment measure design for the applicable jurisdiction see weblinks under Additional Resources below Flow Duration Outlet Structures Practical Design Considerations Low flow Orifice Sizing The diameter of the low flow bottom orifice is an important design parameter for flow duration facilities since flows discharged through this outlet should be at or below the project threshold for controlled flows Qcp However maintenance and or other practical considerations may dictate a practical limit to how small this orifice may be which may be larger than the optimal theoretical diameter determined by Auto Pond As an example the SWMMWW specifies a minimum orifice diameter of 0 5 inches for flow restrictor ass
221. w Groundwater Flows Commercial Toolbox Area in Basin Available Pervious Acres A BUrbanFlat 0 52 0 Show Only Selected Available Impervious Acres v Roads Flat 0 5 B UrbanMod 5 102 B Urban Steef 0 20 0 BexkModpiUg Roads Steep 10 202z M BUrbanVeySp20z 0 Di Forest Flat 5 Dub gt 202 Roof Area Driveways Flat 0 5 C D Forest St 10 20 0 E D Forest Verp 20 t M CD Shub F05 T E D Shrub Med 5 1077 g Driveways Mod 10x B D vewaysSWTUZUz M Driveways Vew gt 202 O M SidewaksFis R5 O C O Shrub St 10 20 o Sheva _ E A 0 Dib Grass Modei 0 Iv C D Grass Stel10 20 Desv Doteasy 07 D a 1 Sidewalks Mod 5 10 Sidewalks 510209 SidewaksVeyp202 M T PakigModbiUzg Parking 51 1020 PakingVegp2Uz Move Elements PerviousT otal fo 7 Actes 4 Impervious Total Ss Actes Basin Total Actes S Load x Savery tonto Sole _ gt E st 6 13 2013 10 31 AM After the point of compliance has been added to the basin the basin element will change A small box with a bar chart graphic and a number will be shown in the lower right corner of the basin element This small POC box identifies th
222. which the native soils have been excavated and replaced with engineered soil The facility can have one or more surface outlets represented by an outlet structure with a riser and multiple orifices or a vertical orifice and weir overflow structure The BAHM2013 bioretention element uses the HSPF hydraulic algorithms to route runoff but the HSPF routing is modified to represent the two different flow paths that runoff can take The routing is dependent on the inflow to the bioretention element and the engineered and native soils capacity to absorb additional runoff HSPF Special Actions is used to check the soil capacity to determine the appropriate routing option Infiltration from the engineered soil to the native soil is also possible depending on the properties of the native soil Bioretention facilities can include an underdrain pipe at a specified depth There is no underdrain for A or B soils The material layers represent the engineered soils i e soil layer s and gravel and their design characteristics thickness and vertical water movement Each engineered soil type has appropriate drainage characteristics assigned based on literature values When a soil type is selected by the user then BAHM2013 automatically assigns the appropriate values for 1 Wilting wilting point 0 1 2 Porosity saturated moisture content 0 1 75 Bay Area Hydrology Model 2013 User Manual March 2014 A alpha constant L lambda cons
223. y Name Basin 1 Outlet 1 Outlet 2 Outlet 3 Downstream Connections 0 Facility Type Maximum Facility Area ac 0 Quick Infiltration Basin Facility Dimensions Bottom Length ft 5 j 5 Right Side Slope HAV Top Side Slope Outlet Structure Data Riser Height ft Riser Diameter in ij 5 Infiltration Measured Infiltration Rate in hr Use Wetted Surface Area sidewalls Total Volume Infiltrated ac ft Total Volume Through Riser ac ft Total Volume Through Facility ac ft Percent Infiltrated Pond Volume at Riser Head ac ft 0 Show Facility Table OpenTable H Size Infiltration Basin eya Target ion H Save xy Load sy 8 30 2013 246PM__ The infiltration basin pond dimensions and parameters are Bottom Length ft Infiltration basin pond length 102 Bay Area Hydrology Model 2013 User Manual March 2014 Bottom Width ft Infiltration basin pond width Effective Depth ft Infiltration basin height from basin pond bottom to top of riser plus at least 0 5 feet extra Left Side Slope H V 0 zero for vertical infiltration basin pond sides Bottom Side Slope H V 0 zero for vertical infiltration basin pond sides Right Side Slope H V 0 zero for vertical infiltration basin pond sides Top Side Slope H V 0 zero for vertical infiltration basin pond sid
224. y head z h y z Equation 4 Substituting for yields 12 Equation 5 Z Hydraulic conductivity and matric head vary with soil moisture content These values can be computed by solving the Van Genuchten s equation Equation 6 for both values Note that y 0 when the soil is saturated 204 Bay Area Hydrology Model 2013 User Manual March 2014 Van Genuchten Equation to calculate total head Ger l 1 il lt 2 Equation 6 Ref SE Blum et al 2001 where total hydraulic head constant SE effective saturation m constant n constant and z elevation head Effective saturation SE can be computed using the following Van Genuchten equation Van Genuchten Equation to calculate effective saturation 0 0 1 j SE Equation 7 Ref 1 ay Blum et al 2001 where 6 water content 0 residual water content porosity a constant y 1 n constant 1 m constant 1 EM A1 A pore size distribution index y bubbling pressure y pressure head total hydraulic head z elevation head and SE effective saturation Ignoring z elevation head results in h hm matric head 205 Bay Area Hydrology Model 2013 User Manual March 2014 Evapotranspiration from the Soil Column Evapotranspiration is an important component of the bioretention facility s hydrologic processes Evapotranspiration removes water from bioretention surface pond

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