Home

(PLRM) User`s Manual - California Stormwater Quality Association

1. Continous Simulation Length 2 Short Simulation O Full Simulation Sawe Project Info Lake Tahoe PLAM v1 0 Figure 3 2 Project Editor The following functions are executed by the Project Editor Project Location Grid No defines the physical location of the water quality improvement project in the Tahoe Basin by designating a PLRM meteorological grid cell Clicking on the button Find Met Grid from the Project Editor will activate an image of the Tahoe Basin overlain with the PLRM meteorological grid Each grid cell is 800 meters by 800 meters You can zoom into the image to find your project area and the associated grid cell Select and enter the grid cell that is closest to the centroid of your project area Only one grid cell can be defined for a Project Defining the grid cell of your Project will execute a temperature and precipitation algorithm in the PLRM that will provide pre processed hourly precipitation and temperature data for your specified location for Water Years 1989 through 2006 Precipitation data is extrapolated to your grid cell using the historical time series of precipitation from the most applicable SnoTel gage and a relationship derived from the Parameter elevation Regressions on Independent Slopes Model PRISM developed at PLRM User s Manual 36 December 2009 Oregon State University PRISM 2008 Temperature data 1s extrapolated to your grid cell using the historical time series of temperature from
2. Key Concept Box recommended by local and regional hydrology guidelines or codes for flood protection Finally the model will not explicitly evaluate the effects of hydrologic modification on downstream channel erosion and associated sediment loads 1 2 PLRM Documentation This User s Manual is one part of the documentation developed for the PLRM Table 1 1 lists three documents that are available to assist users in applying and understanding the PLRM Table 1 1 Description of PLRM Documentation The manual is the primary document describing how to use the PLRM User s Manual The manual provides information that is directly applicable for setting up and performing basic PLRM simulations The guide provides simple example applications of the PLRM The Applications Guide example applications walk the user through the basic steps of developing a PLRM simulation and interpreting results The document supplements the User s Manual by providing the interested reader with more background on the PLRM program structure development of data sets supporting the PLRM and technical algorithms used to develop data sets as well as inform computational Model Development a j methods Although the information in this document will not generally Document es be needed to perform basic simulations it provides important background on the fundamental model structure and supports a more in depth understanding of model computations and a baselin
3. PLRM User s Manual 99 December 2009 As shown in Figure 8 11 storm water that passes through the filter media is considered Treated Flow The quality of Treated Flow from the Bed Filter is assigned CECs for pollutants of concern as defined in the Bed Filter Editor If the incoming flow rate exceeds the treatment flow rate the Equalization Basin Volume above the filter bed will begin to fill Storm water that passes through the bypass outlet when the Equalization Basin Volume is exceeded is considered Bypass Flow The quality of Bypass Flow is equal to the influent concentration of the storm water entering the Bed Filter The Bed Filter Editor allows for modification of CEC values but any modification should be justified by the user Customized Filtration Rate The Bed Filter Editor provides a function that allows the user to customize Filtration Rate as a function of the Equalization Basin Volume to account for head dependent filtration rates or variable stage area relationships This function can be accessed by clicking on the Custom Volume Discharge Curve button from the Bed Filter Editor Figure 8 10 Clicking on the button will activate the Volume Discharge Curve Editor Figure 8 12 The column Volume cf divides the user defined Equalization Basin Volume entered in the Bed Filter Editor into ten increments For each increment the user can set the Filtration Rate inch hr of the Bed Filter The following functions can be performed f
4. To access the Wet Basin Editor add a Wet Basin to the Schematic Window and double click on the Wet Basin icon This will bring up the Wet Basin Editor as shown in Figure 8 7 Y EN Wet Basin Editor Wet Basins Edit Object Mame WetBasinl Design Parameters Parameters Default Value User Value Wet Pool Yolume 2500 2500 wet Pool Footprint 1000 1000 Minimum HRT of Wek Pool 24 24 Surcharge Basin Yolume 2500 Brim Full Draw Down Time 48 CICK ere TO 66 S0Reatic Wiin parameter ESOO Characteristic Effluent Concentration Pollutants of Concern Default Value User Value 10 10 10 10 0 95 0 95 0 1 0 1 0 1 0 1 0 04 0 04 Lake Tahoe FLAM v1 0 Figure 8 7 Wet Basin Editor PLRM User s Manual 94 December 2009 The following are data entry fields for a Wet Basin e Name edit the default name of the Wet Basin if desired By default the PLRM will name Wet Basins in a Scenario sequentially as WetBasin1 WetBasin2 etc e Flows to contains a drop down box to select the object that receives flow from the Wet Basin Objects that can receive flow include junctions outfalls dividers or another SWT Only previously created objects in the Schematic Window will be available to select from the drop down box Design Parameters The Wet Basin Editor requires entry of key Design Parameters to simulate the performance of the Wet Basin for capturing and treating storm water runoff Key Design Parameters includ
5. e Volume Load Removed average annual runoff volume and pollutant load removed by the SWT facility e Change Removed Influent relative percent of average annual runoff volume and pollutant load removed Note that the subtraction or addition of PSCs and HSCs to the catchment s draining to an SWT will influence the load removed by the SWT e Capture 1 Bypass Influent average annual hydraulic capture of the SWT or the percent of the influent volume captured and treated and or infiltrated by the SWT The percent capture 1s an important performance metric that provides an indication of the effectiveness of the hydraulic design of the SWT relative to inflowing storm water characteristics For example a target percent capture of 80 90 is common in practice because this range is typically the point of diminishing returns where small incremental increases in the percent capture require a much larger facility Hydraulic capture increases for short drain times or high infiltration filtration rates Short drain times decrease the time it takes for an SWT to recover its storage capacity For actual SWT facilities short drain times may not provide the hydraulic residence necessary to achieve the Characteristic Effluent Concentrations CECs assumed in the PLRM For this reason recommended limits for several input parameters that affect hydraulic capture are provided in Section 10 2 For example the minimum recommended brim full d
6. A description of each field can be reviewed by opening the table in Design View in Access Reference Section 4 2 of the Model Development Document BuildupParcels Description The table includes SWMMS code required to simulate buildup of pollutants for each land use and associated pollutant of concern Because the PLRM does not use SWMMS5 algorithms to simulate the buildup of pollutants all values in this table are zero Structure A description of each field can be reviewed by opening the table in Design View in Access Reference None cited Pollutant buildup is not simulated in the PLRM but the code is transferred from the PLRM Database to the SWMM5 input file to ensure the SWMM5 simulation executes correctly PLRM User s Manual 137 December 2009 CatchmentValidationRules Description The table includes default recommended ranges for key Input Parameters that are associated with data entry for defining the properties of a catchment Structure Values in Min and Max columns are used by the Recommended Range Report to flag user entered values that are outside the Min or Max value The Flag column categorizes the type of message that will be generated as a Note Warning or Error Reference See Section 10 2 of this Manual Codes Description This is the primary table used within the PLRM Database to relate internal fields and to define fields The PLRM Database uses values in the codes column to relate to most other fields
7. Characteristic Runoff Concentrations Pollutant Delivery Factors Pollutants of Concern mg L Fines A Road Risk T55 FSP TP SRP TN Dissolved Particulates High Moderate Low Lake Tahoe PLAM v1 0 Figure 2 12 Road Conditions Editor The Road Conditions Editor is divided into three sections Within each section the user enters information by Road Risk category This allows for varying road conditions and water quality strategies to be explored by Road Risk category The three sections provide the following functions 1 Pollutant Potential defines the relative magnitude of available pollutants that may be transported during a storm water runoff event from a road Pollutant potential is adjusted by the presence or absence of varying levels of road abrasive control strategies and varying road shoulder conditions 2 Sweeping Effectiveness defines pollutant recovery actions associated with street sweeping Sweeping effectiveness is adjusted based on the type of sweeper and the frequency of sweeping 3 Characteristic Runoff Concentrations CRCs representative concentrations for each pollutant of concern in storm water runoff based on the Road Risk category Pollutant Potential and Sweeping Effectiveness CRCs are dynamically calculated within the Road Conditions Editor as information is entered for Pollutant Potential and Sweeping Effectiveness PLRM User s Manual 23 December 2009 For this example enter th
8. Figure 6 6 Land Use Conditions Editor Parcel Methodology PLRM User s Manual 68 December 2009 Note that the current version of the form will display all available urban land uses in the PLRM but the Area for land uses that are not defined to be present in the Land Use Editor will be equal to zero While the form would allow entry of information for urban land uses not present in the catchment the program would not use the input BMP implementation is entered in the Pollutant Source Controls Editor by defining the percent of area for each urban land use with completed BMPs In typical practice the amount of BMP implementation is reported based on the number of parcels with completed BMPs If data is only available on the number of parcels with completed BMPs for existing conditions this data will need to be converted to an area using GIS or by assuming an average size for the parcels There are two types of BMP Implementation that can be defined in the PLRM Source Control Certificates and BMP Retrofit Certificates The definition of each which is based on TRPA definitions is as follows Source Control Certificate a property has completed PSC implementation 1 e pervious areas of the property are stabilized However the property has recognized constraints that do not allow for HSC implementation to the typical standard 1 e storage of runoff from 20 year 1 hour storm on the property In the PLRM defining a property to have
9. Wet Basins require perennial or seasonal base flow and an outlet design that maintains the wet pool Wet Basins can be designed with extended detention of storm water by providing storage above the wet pool surface typically called surcharge storage Wet Basins provide pollutant load reductions from 1 volume reduction via evaporation of the wet pool and 2 improvements in effluent quality relative to influent quality A Wet Basin is also known as a wetland basin retention pond wet pond storm water wetland etc Urban Land Use a subset of land uses classified by the TMDL Land Use GIS Layer specifically Single Family Residential Multi Family Residential CICU Commercial Institutional Communications Utilities and Vegetated Turf Primary Roads and Secondary Roads are a special class of Urban Land Uses termed Road Land Uses PLRM User s Manual 154 December 2009
10. and 8 below are examples of Stable and Protected road shoulders The designation was determined based on answers to the following two questions ae lo p k e Photo 6 Stable and Protected Photo 7 Stable and Protected o 8 Stable and Protected L Question 1 Could storm water runoff collect along the road shoulder and cause erosion NO stable in Photo 6 conveyance is stabilized by the rolled curb and gutter in Photo 7 conveyance is stabilized by the dense vegetation in Photo 8 storm water runoff will not collect and convey as it will sheet flow off the road Question 2 Can automobiles and or snow plow activity disturb a significant portion of the unpaved road shoulder NO protected in Photo 6 and Photo 7 the majority of the unpaved area in the shoulders is protected by dense vegetation in Photo 8 the steep natural topography will deter shoulder parking and snow plow disturbance Determination Stable and Protected PLRM User s Manual 65 December 2009 6 1 2 2 Sweeping Effectiveness The Sweeping Effectiveness section of the Road Conditions Editor defines pollutant recovery actions associated with street sweeping where street sweeping assumes the entire road 1s swept Sweeping effectiveness 1s adjusted based on the type of sweeper used and the frequency of sweeping For each Road Risk Category the user selects a sweeper type from the Type of Sweeper drop down box in the Road Conditions Edit
11. informs the user of calculated Brim Full Draw Down Time and average Infiltration Rate based on their values entered for each volume increment Information entered in the form is saved and the PLRM returns to the Dry Basin Editor e Auto Calculate restores the values of Treatment Rate and Infiltration Rate calculated based on design parameters entered in the Dry Basin Editor e Cancel disregards changes to the form and returns to the Dry Basin Editor PLRM User s Manual 88 December 2009 PLRM User s Manual Volume Discharge Curve Editor Note Changing these values will overwrite any previously entered values for drawdown time or infilration rate Volume cP D 3 333 333 666 667 1000 1333 333 1666 667 2000 2333 333 2666 667 3000 Lake Tahoe PLAM v1 0 Treatment Rate cfs Infilt Rate tnthri j 0 01157 0 01157 0 01157 0 01157 0 01157 0 01157 0 01157 0 01157 0 01157 0 01157 o 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 Save and Close Auto Calculate Cancel Figure 8 3 Dry Basin Volume Discharge Curve Editor 89 December 2009 8 2 Infiltration Basin An Infiltration Basin is a volume based SWT designed to detain and infiltrate storm water runoff Compared to a Dry Basin an Infiltration Basin does not include a treatment outlet that discharges treated storm water as surface flow Infiltration Basins provide pollutant load reductions from volume reductions via infiltratio
12. 06 0 1 0 02 Remaining Area Draining To Outlet 100 0 50 0 06 0 1 0 02 Edit HSC Facility Secondary Roads 4 acres i 0 i Edit HSC Facilit Area Draining to Infiltration Facilities Y Edit HSC Facility Area Draining To Pervious Dispersion Areas Remaining Area Draining To Outlet hi Lake Tahoe PLRM v1 0 Figure 7 1 Drainage Conditions Editor Road Methodology PLRM User s Manual 71 December 2009 In the PLRM hydrologic calculations are aggregated by land use This approach supports land use based pollutant load computations by facilitating hydrologic analysis by land use e g routing a portion of the Secondary Roads to a pervious area or installation of private property BMPs within residential land uses Key Concept Box Note that land uses are typically distributed through a catchment and aggregation by land use does not allow Land uses are typically distributed through a catchment and aggregation by land use does not allow flows or loads to be tracked geographically within a catchment if results are needed flows or loads to be tracked geographically within a catchment if results are needed for a particular portion of a catchment it should be divided into two or more catchments Additionally if hydrologic properties of a single land use are significantly different from one for a particular portion of a portion of the catchment to another it may be catchment it should be divided advan
13. 53 198 07 25 45 Figure 9 2 Scenario Report The following summarizes the output included in each section of the Scenario Report Global Information The Global Information section lists the Project and Scenario names the number of years simulated and the meteorological grid cell used in the simulation The number of years simulated should be 18 for a Full Simulation or 6 years for a Short Simulation Global Information also includes the time the PLRM Scenario was created and the time that PLRM Scenario was run that created the Scenario Report being viewed Catchments The Catchments section provides a summary of the average annual runoff volumes and pollutant loads for pollutant of concern for each catchment in the Scenario PLRM User s Manual 111 December 2009 Storm Water Treatment The Storm Water Treatment section summarizes for each SWT facility in the Scenario the following e Total Influent average annual runoff volume and pollutant load to the SWT facility e Bypass Stream average annual runoff volume and pollutant load not captured by the SWT facility 1 e runoff and pollutant load bypassing the SWT facility e Treatment Stream average annual runoff volume captured and treated by the SWT facility average annual pollutant load remaining after treatment by the SWT facility e Total Effluent combined bypass stream and treated stream average annual runoff and pollutant load downstream of the SWT facility
14. A Treatment Vault is a generic flow based SWT facility where treatment may occur via a number of processes The default CECs for Treatment Vaults in the PLRM is based on storm water performance data for hydrodynamic separators a proprietary type of Treatment Vault With supporting effluent quality data a user may modify CEC values in the Treatment Vault Editor and model any flow based SWT facility Treatment Vaults are considered flow through devices in the PLRM and storage is considered to be negligible To access the Treatment Vault Editor add a Treatment Vault to the Schematic Window and double click on the Treatment Vault icon This will bring up the Treatment Vault Editor as shown in Figure 8 15 Ey Treatment Vault Editor a Se Treatment Vaults Edit Object Mame Treatmentwanltl Outlet Design Parameters Parameters Default Value User Value Maximum Treatment Flaw 0 COE era fo see schemat MALA parameter OECTA Characteristic Effluent Concentration Pollutants of Concern Default value User value 46 45 43 45 Lake Tahoe PLAM v1 0 Figure 8 15 Treatment Vault Editor PLRM User s Manual 104 December 2009 The following are data entry fields for a Treatment Vault e Name edit the default name of the Treatment Vault if desired By default the PLRM will name Treatment Vaults in a Scenario sequentially as TreatmentVaultl TreatmentVault2 etc e Flows to contains a drop down box to select
15. Conditions Editor and defined as disconnected in the Drainage Conditions Editor see Section 7 While pollutant generation and impervious area connectivity are independent input parameters in the PLRM they are interdependent components of the pollutant load calculations in the PLRM Note that it will likely be more efficient to assess road shoulder condition and impervious area connectivity of roads at the same time Therefore it is recommended that the user review Section 7 of this manual before developing input parameters for road shoulder conditions Guidance for Estimating Road Shoulder Conditions The following is recommended guidance for populating the Road Shoulder Conditions table within the Pollutant Potential section of the Road Conditions Editor The necessary input for the Road Conditions Editor is shown in Table 6 3 There are four types of road shoulder conditions defined in the PLRM 1 Erodible 2 Protected 3 Stable and 4 Stable and Protected Within a catchment the percentage of each road shoulder condition by Road Risk Category must be tabulated where the sum equals 100 PLRM User s Manual 57 December 2009 Table 6 3 Road Shoulder Conditions Input Road Shoulder Conditions Road Risk Categor Erodible Protected Stable SALOU Bory Protected ma se Ooa g o Moers w w oo S o The steps below are recommended activities that occur outside of PLRM to develop input parameters Step 1 Qua
16. Help x A Ay Search 5 2 Favorites 4 z4 y a E La Wes Ea A rel Address C Program Files PLRM Engine Validation yvalidation html Google v f search Br Ly Bookmarks Y AutoFill 4 Recommended Range Report Figure 2 17 Recommended Range Report Viewing Scenario Results When the PLRM completes a run the program will return to the Schematic Window To view results for a completed run click on the Report button on the Schematic Window within the Function Toolbar Figure 2 6 This will bring up the Scenario Report that includes the results for pollutant loading and runoff volumes for the simulated Scenario Figure 2 18 Note that the results shown in the Scenario Report are pollutant loads and not pollutant load reductions The PLRM calculates pollutant loads for a Scenario within a Project Pollutant load reductions produced by the PLRM are the result of comparing multiple Scenarios within the same Project PLRM User s Manual 30 December 2009 that have completed Scenario Reports using the Scenario Comparison Report discussed below Figure 2 18 illustrates the Scenario Report for the completed Scenario which is described in detail in Section 9 of this User s Manual The Scenario Report provides results on average annual runoff volumes and average annual pollutant loads for pollutants of concern The Scenario Report is organized into sections that describe pollutant loading from simulated Catchments the perf
17. PLRM so there are no changes to make on the Road Methodology portion of the Drainage Conditions Editor Click the tab Parcel Methodology This will switch the form in the Drainage Condition Editor to the Parcel Methodology Figure 2 14 EX Drainage Conditions Editor Parcel Methodology Road Methodology Drainage Conditions Pery Imperv Impervy Dep Dep of Area Area DCIA Ksat Storage Storage Single Family Residential 8 acres Area ac ac in hr in in Area Draining To Infiltration Facilities 25 2 0 8 100 0 99 0 1 0 02 Edit HSC Facility Remaining Area Draining To Outlet 75 6 2 4 50 0 99 0 1 0 02 Multi Family Residential O acres Area Draining To Infiltration Facilities Edit HSC Facility Remaining Area Draining To Outlet CICU O acres Area Draining To Infiltration Facilities Edit HSC Facility Remaining Area Draining To Outlet Vegetated Turf O acres Area Draining To Outlet All Others O acres Area Draining To Outlet Lake Tahoe PLRM v1 0 Figure 2 14 Drainage Conditions Editor Parcel Methodology The form for the Parcel Methodology 1s similar to the Road Methodology except for the following differences e There is no option to specify the percentage of Area Drainage to Pervious Dispersion Areas e The PLRM automatically inputs the percentage of Area Draining to Infiltration Facilities and the Remaining Area Draining to Outlet This
18. Schematic Window The buttons within the Schematic Window are organized within three toolbars e Object Toolbar Contains all objects that can be added into a PLRM simulation Catchments SWT facilities Junctions Flow Dividers and Outfalls e Function Toolbar Contains commands for the program to Save Run and Display Results e View Toolbar Contains buttons to adjust the view The toolbar also contains the selection command arrow icon which allows selection and movement of specific objects as well as access to input forms for specific objects The toolbars may be moved and placed anywhere in the Schematic Window PLRM User s Manual 14 December 2009 Return to Compare Projectand Scenariosto View Export About Scenario WE Run Estimate Load Scenario Scenario PLRM l runcrion M Scenario Scenario Reductions Report Report Version View Toolbar Toolbar amager AW Lake Tahor PLRM v1 0 Project Name DefaultProject Scenario Nan Project Manager sig Save l DefaultSce nario Run Y Compare Scenarios li View Report Pi xport Report About a f A EE fa Create a Catchment Object Junction Selection Tool Adjust Window Toolbar o uta Size Flow Divider Ly lt Dry Basin y Infiltration Basin i igo Wet Basin Cartridge Filter ee Y AN Treatment Vault or User Defined SWT Figure 2 6 Schematic Window and Functions As an example exercise for the purposes of following alo
19. Tool Adjust Window Toolbar outfall Size A lt 4 Flow Divider LJ LJ lt Dry Basin Infiltration Basin ts Wet Basin ne Y Bed Filter a Cartridge Filter Treatment Vault or User Defined SWT Figure 4 1 Schematic Window and Functions The buttons are organized within three toolbars and that may be moved and placed anywhere in the Schematic Window e Object Toolbar Contains all objects that can be added to a PLRM simulation A hyperlink to guidance in Section 8 of this Manual describing each object is provided below To use the hyperlink function hold the CTRL button on your keyboard and click on a hyperlink Catchments Dry Basins Infiltration Basins Wet Basins Bed Filters Cartridge Filters Treatment Vaults or User Defined SWT Junctions Outfalls and Flow Dividers O O Oo PLRM User s Manual 41 December 2009 e Function Toolbar Contains commands for the program to Save Run and Display Results The following functions are accessible from the toolbar Where applicable a hyperlink to guidance in this Manual describing each function is provided below To use the hyperlink function hold the CTRL button on your keyboard and click on a hyperlink o Project Manager closes the Scenario and returns to the Project and Scenario Manager Save saves the current inputs for the Scenario o Run executes a PLRM simulation for a Scenario with completed input S
20. User s Manual 127 December 2009 Unit Area Storage for an Infiltration Facility Flagged As Range Message Reference Guidance PLRM User s Manual Note Low 1 0 inch impervious area High 1 0 inchAmpervious area Current TRPA regulations require containment at a minimum of the storm water runoff volume generated by a 20 year return period 1 hour duration design storm from impervious surfaces The calculation of runoff volume is made by multiplying the intensity of the 20 year 1 hour design storm taken as one inch of precipitation in one hour by the impervious surface area A value other than 1 inch indicates the user is evaluating an infiltration facility that is sized for a runoff volume generated by something other than one inch of precipitation 1 e the current design storm The minimum and maximum values for the recommended range were both set to 1 inch to flag when the user is evaluating an alternative design sizing criteria for an HSC Based on TRPA regulations for the 20 year 1 hour storm which equates to 1 inch of precipitation over the impervious drainage area The PLRM allows the user to adjust the sizing criterion for an Infiltration Facility by adjusting the unit area storage value This may be useful to evaluate situations where Infiltration Facilities cannot be sized to store the 20 year 1 hour storm because of physical constraints For example it s common for water quality improvement proj
21. and the PLRM returns to the Infiltration Basin Editor e Auto Calculate restores the values of Infiltration Rate based on design parameters entered from the Infiltration Basin Editor The default is a constant infiltration rate for all storage volume increments greater than zero e Cancel disregards changes to the form and returns to the Infiltration Basin Editor PLRM User s Manual 92 December 2009 Volume Discharge Curve Editor Note Changing these values will overwrite any previously entered values for drawdown time or infiltration rate Infilk Rate Cin hr o 0 4 0 4 0 4 0 4 0 4 0 4 0 4 0 4 Save and Close 0 4 4uto Calculate 0 4 Cancel Lake Tahoe PLAM v1 0 Figure 8 6 Infiltration Basin Volume Discharge Curve Editor PLRM User s Manual 93 December 2009 8 3 Wet Basin A Wet Basin also known as a wetland basin retention pond wet pond constructed wetland etc 1s aclass of volume based SWT that includes a permanent or seasonal pool of water typically called a wet pool Wet Basins require perennial or seasonal base flow and an outlet design that maintains the wet pool Wet Basins can be designed with extended detention of storm water by providing storage above the wet pool surface typically called surcharge storage Wet Basins provide pollutant load reductions from 1 volume reduction via evaporation of the wet pool and 2 improvements in effluent quality relative to influent quality
22. and Hydrologic Source Controls To enter information on Hydrologic Properties and Hydrologic Source Controls HSCs click on the button Step 5 Define Drainage Conditions from the Catchment Properties Editor This will bring up the Drainage Conditions Editor as shown in Figure 7 1 There are two tabs on the Drainage Conditions Editor 1 Road Methodology and 2 Parcel Methodology The Road Methodology tab defines hydrologic properties for Primary Roads and Secondary Roads and the Parcel Methodology tab defines hydrologic properties for all other non road Urban Land Uses The Drainage Conditions Editor is organized by land use and includes an Area column and an Impervious Area column with values populated based on information entered in the Land Use Editor Note that the form will display all available urban land uses for the specific methodology but the Area for land uses that are not defined as present will be zero While the form would allow entry of information for urban land uses not present in the catchment the program would not use the input Drainage Conditions Editor fohment JD Catchi f Area Jac Parcel Methodology Road Methodology Drainage Design Pery Impery Impery Dep Dep of Area Area DCIA Ksat Storage Storage Primary Roads O acres Area ac ac 0 in hr in in Area Draining To Infiltration Facilities o 0 100 0 06 0 1 0 02 Edit HSC Facility Area Draining To Pervious Dispersion Areas 9 0 0 100 0
23. and conditions Foreword and Acknowledgements The Pollutant Load Reduction Model is part of a multi stakeholder effort to provide technical tools for project planners funders implementers and regulators to work collaboratively to minimize the deleterious effects of urban storm water on the remarkable clarity of Lake Tahoe a keystone in the ecological and economic health of the Lake Tahoe Basin This product would not be possible without the generous participation of several Basin regulatory and project implementing entities This specific product 1s authorized pursuant to Section 234 of the Water Resources Development Act of 1996 PL 104 303 which provides for coordinated interagency efforts in the pursuit of water quality and watershed planning This product was funded by IA iva SYSTEM OF ES PUBLIC LANDS US Army Corps SOUTHERN NEVADA of Engineers e PUBLIC LAND MANAGEMENT ACT er www blm gov snplma Sacramento District Support and in kind services were provided by SN TAHOE UCDAVIS b i yr UNIVERSITY OF CALIFORNIA AGENCY This product was prepared by nhc Geosyntec NONATURE consultants ecosystem science design TABLE OF CONTENTS 1 0 INTRODUCTION AND OVER VEE Wa ciao 1 Lal INTENDED USE OF THE RIM a ees see de ee ee 1 1 2 PERM DOCUMENTATION id lis 2 LS USER S MIANUAL CONTENT oia ia 3 1 4 MODELING APPROACH AND CAPABILITIES cccsceccsceccececcscsceccececescecesescecescecsceceses
24. associated with SWT facilities as well as default recommended ranges for Characteristic Effluent Concentrations CECs for each SWT facility Structure Values in Min and Max columns are used by the Recommended Range Report to flag user entered values outside the Min or Max value The Flag column categorizes the type of message that will be generated as a Note Warning or Error For CECs the Min and Max values are equal in this table This ensures that any value other than the default CEC value will be flagged by the Recommended Range Report if CECs are changed in the SWT Editors e g Dry Basin Editor Wet Basin Editor Reference See Section 7 1 of the Model Development Document for more information on SWT design parameters See Section 7 2 of the Model Development Document for more information on default CEC values PLRM User s Manual 141 December 2009 Options Description This table includes default values that standardize the parameters used to define a PLRM Simulation relative to the various analysis options that can be performed in a SWMMS5 simulation Structure Each field in the Category column describes a SWMMS5S analysis option The Parameter column is the value or option used for a PLRM simulation The Start Date and End Date fields are blank because these values are populated based on the user s selection of either a Short Simulation or Full Simulation from the Project Editor Reference See Appendix D of the SWWM5 Us
25. criteria Adjusting the default value will adjust the storage volume for the Infiltration Facility as a function of the tributary impervious area Adjusting the default value may be useful in certain cases For example it s common for public water quality improvement projects that primarily target storm water runoff from roads to implement HSCs that store less than 1 inch or runoff because of constraints in the right of way that limit storage opportunities Section 10 2 provides additional guidance on modifying this Input Parameter User s Manual 81 December 2009 e Saturated Hydraulic Conductivity Infiltration in an Infiltration Facility is simulated using the Green Ampt equation Values for saturated hydraulic conductivity Ksat are the most sensitive input parameter for the Green Ampt equation The default value in the Infiltration Facility Editor is 0 5 inches hour Section 10 2 provides additional guidance on modifying this Input Parameter In PLRM Version 1 defining an Infiltration Facility will add a minute amount of area to the simulation above that specified by the user in the Land Use Editor For example in a typical catchment if all impervious area was routed to Infiltration Facilities this would increase the area simulated by roughly 0 5 relative to the area defined by the user in the Land Use Editor This minor discrepancy has been tested and does not appear to influence results no action is required by the user A
26. for Tahoe Basin urban areas using a GIS analysis of the Tahoe Basin Digital Elevation Model DEM available for download at http tahoe usgs gov DEM html The calculation of average slope only needs to provide a representative value for a user defined catchment A high level of accuracy 1s not required In most cases the following calculation will suffice for average slope maximum catchment elevation minimum catchment elevation length of catchment If a significant grade break is evident in the catchment e g half the catchment is a 20 slope and the other half 1s 2 slope the user may want to consider modeling two separate catchments 122 December 2009 Percentage DCIA Flagged As Range Message Reference Guidance PLRM User s Manual Note Low 10 High 80 The percentage of directly connected impervious area DCIA defined by the user can significantly affect runoff volumes Given the significance of this parameter values entered by the user for DCIA outside the recommended range are flagged The message is only categorized as a Note because values outside the recommended range can be a common occurrence No specific reference is cited The recommended range was developed to highlight values entered by the user that indicate the impervious area is either highly connected or highly disconnected When a user enters a value that is below the recommended minimum the user has defined the imperv
27. for capturing infiltrating and treating storm water runoff Key Design Parameters include e Water Quality Volume cf storage capacity below the bypass outlet designed for water quality treatment e Footprint sf surface area that will typically be inundated approximately the area at the average design depth e Infiltration Rate in hr characteristic rate of infiltration expected over the life span of the SWT while factoring in assumptions for anticipated or committed maintenance The recommended range is 0 05 0 5 inches hour e Brim Full Draw Down Time hr time it takes for the Water Quality Volume to completely drain through treatment outlet s without consideration of the infiltration rate The recommended range is 48 72 hours An illustration of how the Design Parameters relate to the conceptual representation of a Dry Basin in the PLRM is accessible from the Dry Basin Editor by clicking on the link Click here to see schematic with parameters descriptions Clicking on the link will bring up Figure 8 2 PLRM User s Manual 87 December 2009 Inflow gt Bypass Flow Treated Flow Brim Full Draw Down Time Figure 8 2 Dry Basin Representation in PLRM The volume of infiltrated storm water as well as an estimate of pollutant load removed with the infiltrated storm water is tracked by the PLRM Surface water that is retained in the Dry Basin and exits through the treatment outlet is cons
28. future version of the PLRM may develop a more automated method to address this minor discrepancy 7 3 2 Pervious Dispersion Area Editor Figure 7 6 displays the Pervious Dispersion Area Editor accessed from the Drainage Conditions Editor EN Pervious Dispersion Area Editor Hydrologic Properties of HSC Receiving Runoff Storage a Default Footprint of Pervious Dispersion Area 5000 Average Slope of Pervious Dispersion Area 0 5 Saturated Hydraulic Conductivity 0 320 Depression Storage 0 1 sq ft Lo infhr in Units Lake Tahoe PLRM v1 0 Figure 7 6 Pervious Dispersion Area Editor PLRM User s Manual 82 December 2009 Four Input Parameters can be adjusted for a Pervious Dispersion Area Footprint of Pervious Dispersion Area the physical area of the Pervious Dispersion Area that will typically be inundated with storm water The default value is 5 000 square feet but the user should always adjust this value when modeling a Pervious Dispersion Area dependent upon their site specific conditions and or proposed project design Average Slope of Pervious Dispersion Area average slope entered as a percent Saturated Hydraulic Conductivity infiltration is simulated using the Green Ampt equation and values for saturated hydraulic conductivity Ksat are the most sensitive input parameter for the equation The default value is 0 5 inches hour Section 10 2 provides additional guidance on this Input Par
29. machine with Pentium processor or higher a Pentium III or highly is recommended e A hard disk with at least 1 gigabyte of free space e A minimum of 256 megabytes of RAM however additional RAM is recommended e Windows XP Service Pack III or newer e Windows Vista with User Account Control turned off e As of December 2009 PLRM has not been tested on Windows 7 Uninstall Procedure The PLRM setup program automatically registers the software with the Windows operating system The software can be uninstalled by clicking on the uninstall icon in the PLRM program group under the Start menu or by navigating to Add Remove programs on the Control Panel PLRM User s Manual 8 December 2009 2 0 Quick Start Guide This Quick Start Guide provides basic information on how to enter required information to successfully build a PLRM simulation and run the program This section does not provide any guidelines regarding how to estimate Input Parameters or how the input forms influence computations and results Sections 3 through 11 of this User s Manual should be reviewed to gain a thorough understanding of the program the Input Parameters required by the program and the guidelines for estimating Input Parameters To Start the PLRM When you run the PLRM setup program you automatically get a new program group called PLRM and associated program icon The PLRM should appear in the start menu under Programs The setup program will also give you
30. not have a permanent pool of water they are designed to drain completely between runoff events To access the Dry Basin Editor add a Dry Basin to the Schematic Window and double click on the Dry Basin icon This will bring up the Dry Basin Editor as shown in Figure 8 1 EN Detention Basin Editor a Dry Basins Edit Object Mame DiryBasinl Flows To Outta Custom Volume Discharge Curve Parameters Default value User Value Design Parameters Water Quality volume 2500 2500 Footprint 1000 1000 Infiltration Rate 0 2 0 2 Grim Full Draw Down Time 60 60 ick here to see schematic with parameter OECO TONS Characteristic Etluent Concentration Pollutants of Concern Default Value User Value 25 25 Lake Tahoe PLAM v1 0 Figure 8 1 Dry Basin Editor PLRM User s Manual 86 December 2009 The following are data entry fields for a Dry Basin e Name edit the default name of the Dry Basin if desired By default the PLRM will name Dry Basins in a Scenario sequentially as DryBasin1 DryBasin2 etc e Flows to contains a drop down box to select the object that receives flow from the Dry Basin Objects that can receive flow include junctions outfalls dividers or another SWT Only previously created objects in the Schematic Window will be available to select from the drop down box Design Parameters The Dry Basin Editor requires entry of key Design Parameters to simulate the performance of the Dry Basin
31. notable discrepancy in output After adding a Pervious Dispersion Area the user should return to the Land Use Editor and subtract out the area from the associated land use that comprises the Pervious Dispersion Area A future version of the PLRM may develop a more automated method to address this discrepancy PLRM User s Manual 148 December 2009 Urban Hydrology Model The PLRM was developed to compute pollutant loading from storm water quality improvement projects in urban areas of the Lake Tahoe Basin The PLRM runs the EPA s Storm Water Management Model version 5 SWMM5 SWMM5 was selected to run the PLRM in part because of its recognized strengths in urban hydrology However SWMMS5 may not be the best model to simulate hydrology and pollutant loading in pervious forested areas of the Tahoe Basin Given the development focus on urban pollutant loading the PLRM should not be used to estimate pollutant loading from forested areas in the Tahoe Basin Groundwater Algorithms PLRM development focused on computations of surface runoff and pollutant loading generated from urban areas The PLRM uses simplified groundwater algorithms to track infiltrated volumes and evapotranspiration The approach will only provide reasonable results for areas with a low water table High groundwater conditions will likely not be accurately depicted although this is more a general limitation of the hydrologic approach in SWMMS and would be difficult to improve up
32. outside recommended ranges for key Input Parameters The Recommended Range Report provides a brief message regarding any suggested actions for the user for any flagged value Section 10 2 of this Manual describes the key Input Parameters that will be flagged the default recommended ranges and any suggested actions for flagged values E Recommended Range Report Microsoft Internet Explorer File Edit View Favorites Tools Help x 2 CA s Search P Favorites H A gt fw H3 te rel Address l C Program Files PLRMiEngineiYalidationywalidation html Google v Y search Eh Ly Bookmarks YE AutoFill 4 Recommended Range Report Figure 9 1 Recommended Range Report The time required to complete a PLRM simulation will likely be on the order of a few minutes but will vary depending on 1 the speed of your computer 2 the complexity of your simulation the presence of SWTs noticeably increases the simulation time and 3 the selection of a Short Simulation or Full Simulation from the Project Editor During the simulation two separate routines will run 1 the first routine is the SWMM5S simulation and 2 the second routine is the PLRM collecting and summarizing the time series of SWMMS output into average annual output After the simulation completes a message box will appear stating that All Results Collected Click OK on the message box The PLRM will return to the Schematic Window and your Scenario PLRM User s
33. pollutant loading among Scenarios using the Scenario Total output at the bottom of the Scenario Report If the user wishes to explore more runoff from a specific catchment attributed to varying the levels of HSC implementation among Scenarios then the Scenario Reports must be compared manually Scenario Reports can be compared manually by first detailed results among Scenarios exporting each Scenario Report using the Export Report then individual Scenario Reports option on the Schematic Window within the Function must be compared manually Toolbar This option allows the user to define a location on their computer where a Scenario Report will be exported in a format that can be viewed copied and edited using any text editor The Export Report button will export the Scenario Report for the active Scenario in the PLRM PLRM User s Manual 115 December 2009 10 0 Parameter Guidance This section provides guidance for defining key model parameters that strongly influence PLRM model results and that require some user judgment to determine The structure of the PLRM was developed to streamline input data entry by limiting the number of parameters accessible from the PLRM Interface to those that are project area specific and are sensitive in terms of influencing PLRM output This structure relieves the burden on the user to develop all input data required to execute a SWMMS simulation Input necessary for a PLRM simulation is similar to some
34. promote sheet flow and avoid concentration of storm water and conveyance along the road shoulder or 2 stabilize the conveyance of storm water and inhibit erosion along the road shoulder Physical improvements are actions that stabilize a road shoulder e g curb and gutter rock lined channel etc Other elements can include vegetation that stabilizes a road shoulder or topography that promotes sheet flow and avoids concentration and conveyance of storm water in the road shoulder The following are key points to consider when judging if a road shoulder is Stable a Following the decision process of Figure 6 4 ask the question Could storm water runoff collect along the road shoulder and cause erosion 1 Ifthe answer is YES then the road shoulder is not stable 11 If the answer is NO then the road shoulder is stable b Visual evidence of erosion in the road shoulder is not required to make a determination that the road shoulder is not stable 2 Protected The road shoulders have physical features e g structures vegetation etc or policies parking ordinances that discourage or minimize disturbance by automobiles and snow plows Defining a road shoulder as Protected means that the majority of the PLRM User s Manual 59 December 2009 pervious portion of road shoulder within the public right of way will remain undisturbed under typical conditions The following are key points and definitions to consider when judging if a road
35. road shoulders do not meet the definitions of stable or protected as discussed above Following the decision process of Figure 6 4 the answer to the following two questions would be YES a Could storm water runoff collect along the road shoulder and cause erosion b Can automobiles and or snow plow activity disturb a significant portion of the unpaved road shoulder PLRM User s Manual 60 December 2009 Developing Road Shoulder Conditions for Formulated Alternatives The methods in the PLRM do not explicitly distinguish or rank the different types of PSCs that could be implemented on road shoulders Itis up to the project designer and project reviewers to assess how proposed PSCs in formulated alternatives will influence the condition of road shoulders in terms of pollutant generation Water quality improvements attributed to PSC implementation on road shoulders is based on the road shoulder condition they create Any PSC that creates the same road shoulder condition is considered equal in the methodology in terms of pollutant generation For example the Road Methodology does not distinguish between curb and gutter and a rock lined channel Using the PLRM definitions for road shoulder condition both curb and gutter and a rock lined channel are PSCs that could create a stabilized road shoulder condition However user discretion should be applied to adjust road shoulder conditions as deemed appropriate For example if an existing rock lined ch
36. schematic with parameters descriptions Clicking on the link will bring up Figure 2 16 Inflow Bypass Flow Treated Flow Brim Full Draw Down Time Figure 2 16 Dry Basin Representation in PLRM For this example enter the information as shown in Figure 2 15 e Water Quality Volume 3 000 cubic feet e Footprint 2 000 cubic feet e Infiltration Rate 0 0 inches hour e Brim Full Draw Down Time 72 hours After completing data entry in the Dry Basin Editor to match Figure 2 15 click the OK button to close the form and return to the Schematic Window PLRM User s Manual 29 December 2009 2 7 Running the Model and Viewing Results At this point all information needed to execute a PLRM simulation has been entered To run the model click on the Run button on the Schematic Window within the Function Toolbar Figure 2 6 As the PLRM begins to run in the background your default web browser will open and display the Recommended Range Report Figure 2 17 which is described in detail in Section 10 2 of this Manual In summary when a value for the input parameters shown in Table 10 2 is outside a recommended range the program will flag the input parameter in the Recommended Range Report for review The Recommended Range Report provides a brief message regarding any suggested actions for the user for any flagged value 4 Recommended Range Report Microsoft Internet Explorer File Edit View Favorites Tools
37. separate definition of the condition of Primary Roads and Secondary Roads within a catchment Note that the methodology applies to primary and secondary roads as a land use and thus includes paved and unpaved areas within the right of way and not just the road pavement areas e The Parcel Methodology defines the condition of predominantly private land uses Single Family Residential Multi Family Residential CICU and Vegetated Turf The Parcel Methodology allows for separate definition of private property BMP implementation for each applicable land use within a catchment 6 1 Road Methodology The PLRM Road MEHIOCO DEy cone new concepts idan Onoon IR and methods to predict the quality of runoff generated from roads The methodology is based on the hypothesis The definitions and methods in that the condition of roads can be correlated to Section 6 1 are focused on characteristic runoff concentrations CRCs for defining CRCs rather than pollutants of concern The key variables that are use to pollutant loads The methods are not influenced by the connectivity of impervious area O to downstream receiving waters application practices and pollutant recovery activities N PEC RET ee predict CRCs include physiographic characteristics PSCs applied to the road shoulder road abrasive appropriate place and methods in A detailed discussion of the research and development of the PERM to incorporate the Road Methodology is provided i
38. shoulder is protected a Typical condition 1s defined as a state that can be reasonably anticipated For example the presence of vegetation in the road shoulder is not much of a barrier to a snow plow but the presence of vegetation indicates that under typical conditions the shoulder 1s not disturbed by plowing and therefore can be considered Protected b Following the decision process of Figure 6 4 ask the question Can automobiles and or snow plow activity disturb a significant portion of the unpaved road shoulder 1 Ifthe answer is YES then the road shoulder is not protected 11 If the answer is NO then the road shoulder is protected c In cases where a policy is implemented to discourage road shoulder disturbance the user may need to judge the success of the policy by estimating the amount of visual disturbance in the road shoulder For example 1f 20 of the road shoulders within a particular block appear to be parked on then the parking ordinance is protecting 80 of the road shoulders on the block 3 Stable and Protected The road shoulders meet the definitions of stable and protected as discussed above Following the decision process of Figure 6 4 the answer to the following two questions would be NO a Could storm water runoff collect along the road shoulder and cause erosion b Can automobiles and or snow plow activity disturb a significant portion of the unpaved road shoulder 4 Erodible The
39. term simulations of hydrology Runoff captured is assumed treated to a characteristic effluent concentration CEC Runoff that is bypassed is assumed to equal influent concentration Current capabilities for SWT in the PLRM include PLRM User s Manual 6 December 2009 e Representation of volume based and flow based SWT facilities based on key design criteria e g water quality storage drain time water quality flow rate infiltration rate etc e Representation of treatment trains e Pre loaded defaults for CECs based on Tahoe Basin data sets supplemented by data from the International BMP Database e Flexibility for user specified CECs to represent advanced or innovative treatment 1 5 Installing and Running the Program Installation Procedure 1 To obtain the PLRM setup program download the PERM_Setup zip file from the TIIMS website http www tims org TIIMS Sub Sites PLRM aspx 2 After downloading the zip file extract the contents to a folder on your computer 3 In the folder run the setup program PLRM_SetUp exe from within the folder Install PLRM 4 Follow the instructions on the screen to install the PLRM Key Concept Box 5 If you have Microsoft Access 2007 on your A user needs to have Microsoft Access 2007 installed on their computer to view the PLRM unsure you need to complete the following for the Database However Microsoft computer skip this step If you do not have Microsoft Access 2007 on your computer o
40. the Soils Table at the bottom of the form To complete the Soils Table the PLRM needs to know the following for each Map Unit defined as present in the catchment PLRM User s Manual 48 December 2009 e of Catchment Area the percentage of the catchment occupied by the soil The sum of percentages for all soils in the catchment should add up to 100 in the Sub totals row of the table e Acres The PLRM automatically calculates the area of each soil using of Catchment Area field and the total area of the catchment entered in Step 1 The data source for deriving the soils distribution within a catchment is the 2006 Tahoe Basin Soil Survey which can be downloaded from the NRCS website for Soil Survey Symbol CA693 http soildatamart nrcs usda gov Survey aspx State CA An alternative method for developing the soils distribution information is to use the Web Soil Survey tools created by the NRCS The tools are accessible at http websoilsurvey nrcs usda gov app HomePage htm PLRM User s Manual 49 December 2009 6 0 Defining Land Use Conditions and Pollutant Source Controls To enter information for Land Uses Conditions and Pollutant Source Controls PSCs click on the button Step 4 Define Land Use Conditions from the Catchment Properties Editor This will bring up the Pollutant Source Controls Editor as shown in Figure 6 1 The Area column will be populated based on information entered in the Land Use Editor The f
41. the most applicable SnoTel gage and a temperature lapse rate developed for use in the Lake Tahoe Watershed Model Additional documentation describing the precipitation and temperature algorithms can be found in the PLRM Model Development Documentation Section 3 and Appendix A Database defines the PLRM Database used for the Project The Default Parameters included within the PLRM Database are not recommended for modification by the user unless the modifications are done to incorporate new or additional data Maintaining consistent Default Parameters in the PLRM Database is recommended because 1t will help to maintain consistency of results generated by multiple user s across multiple project areas Additionally the structure of the PLRM Database should not be modified only data within the database Section 11 of this Manual describes the PLRM Database Continuous Simulation Length this function provides an option to reduce the run time of a PLRM simulation by reducing the length of the continuous simulation A Short Simulation will run a subset of the current PLRM time series Water Years 1990 through 1996 A Full Simulation will run the complete PLRM time series Water Years 1989 through 2006 The intent of providing the Short Simulation option is to allow the user to decrease run times when creating and testing a Scenario The time period for the Short Simulation was selected because it includes Water Years with above average below av
42. transfer the selected land use to the list box titled Selected Land Uses as well as add the land use to the table at the bottom of the form For this example we 1l assume a simple residential catchment serviced by secondary roads Following the procedure above add the following land uses to Selected Land Uses Secondary Roads ROW and Single Family Residential Next the program needs to know the percentage of the total catchment area that each land use occupies Enter the information as shown in Figure 2 9 in the column of Catchment Area where Secondary Roads occupies 20 of the catchment and Single Family Residential occupies the remaining 80 of the catchment The acreage of each land use is calculated and displayed in the Acres column of the table The PLRM provides a default estimate of percent impervious area for each land use Impervious We ll use the defaults for this example however in practice this value should be changed or confirmed by the user for each land use because impervious area can significantly affect surface runoff in a catchment Finally click OK to save the information entered and return to the Catchment Properties Editor PLRM User s Manual 18 December 2009 Ey Land Use Editor Catchment Land Uses Catchment AO Cato f Area Tac Available Land Uses Selected Land Uses vegetated Burned Secondary Road ROW Single Family Residential Erosion Potential 5 Land Use of Catchment Area Impervious
43. 1 Kneeridge gravelly sandy loam 2 to 9 percent Next the program needs to know the percentage of the total catchment area that the Map Unit occupies Enter the information as shown in Figure 2 10 in the column of Catchment Area where the 7171 Kneeridge overlays 100 of the catchment Finally click OK to save the information entered and return to the Catchment Properties Editor EW Soil Editor Soil Type Distribution Cafoiment io Catch fArea tac Available Map Units Selected Map Units 7151 Jorge very cobbly fine sandy loam 5 to 15 percent 7171 Kneeridge gravelly sandy loam 2 to 9 per 7152 Jorge very cobbly fine sandy loam 15 to 30 percen 7153 Jorge very cobbly fine sandy loam 30 to 50 percen 7154 Jorge very cobbly loam 2 to 15 percent slopes ext 7155 Jorge very cobbly loam 15 to 50 percent slopes es 7156 Jorge Tahoma complex 15 to 30 percent slopes 715 Jorge Tahoma complex 30 to 50 percent slopes 7161 Kingsbeach stony sandy loam 2 to 15 percent slope 7172 Kneeridge gravelly sandy loam well drained 5 to 15 Map Unit o of Catchment Area Sub totals 7171 Kneeridge gravelly sandy loam 2 to 9 percent slopes extremely stony Lake Tahoe PLAM v1 0 Figure 2 10 Soils Editor PLRM User s Manual 20 December 2009 2 4 Land Use Conditions and Pollutant Source Controls To enter information for Land Uses Conditions and Pollutant Source Controls PSCs click on the button Step 4 Define Land Use Conditi
44. 2 1 of this Manual to understand the capabilities of the project area or catchment that can be modeled However if a user is modeling areas that are smaller or larger than the recommended size they should first review Section model and the potential 12 1 of this Manual to understand the capabilities of the situations where the PLRM may model and the situations where the PLRM may not not generate appropriate output generate appropriate output for small and large catchments The PLRM may eventually support broader objectives beyond prediction of the relative performance of storm water project alternatives However additional development testing and an institutional framework for supporting the PLRM are needed to expand the use of the PLRM The structure of the PLRM was designed to be flexible and robust so that future refinements can efficiently improve upon the PLRM without the need to incorporate significant redevelopment or rebuilding of the model structure PLRM User s Manual 1 December 2009 The PLRM is not intended to predict pollutant loads in non urbanized settings in the Tahoe Basin The PLRM should not be used to size facilities and conveyances for flood The PLRM should not be used to protection The PLRM will not replace tools and models size facilities and conveyances for flood protection The PLRM will not replace tools and models recommended by local and regional hydrology guidelines or codes for flood protection
45. 5 December 2009 6 1 2 1 Pollutant Potential Pollutant Potential further refines estimated CRCs generated from each Road Risk category based on road abrasive applications and road shoulder conditions This is done separately for Primary and Secondary Road land use categories In the Pollutant Potential section of the Road Conditions Editor the user inputs the road abrasive application strategy and the road shoulder conditions for each Road Risk Category in a catchment The following guidance describes how to define 1 road abrasive application control strategies and 2 road shoulder conditions 6 1 2 1 1 Road Abrasive Application Strategy Road abrasive application strategies in PLRM are intended to represent long term programmatic efforts to minimize the total mass of road abrasives applied while maintaining safe driving conditions A general description of each strategy is provided in Table 6 2 Each strategy in Table 6 2 can be selected in the PLRM drop down box titled Road Abrasive Application Strategy The road abrasive application strategy that best fits each Road Risk Category should be selected If a Road Risk Category in your catchment does not receive road abrasives select Advanced Control Measures Table 6 2 Road Abrasive Application Strategies Road abrasive applications are minimized to the extent possible while maintaining traffic safety Abrasive durability and chemical quality are Minimal Control controlled to reduce generat
46. A Code Current regulations for BMP implementation require the stabilization of pervious areas as well as the containment of storm water runoff from impervious surfaces on individual parcels The calculation of the runoff volume required for storage and infiltration on a parcel is made by multiplying the intensity of the 20 year 1 hour design storm generally taken as one inch of rain in one hour by the impervious surface area associated with the parcel The level of BMP implementation can be defined for each urban land use where urban land uses include Single Family Residential Multi Family Residential CICU and Vegetated Turf To enter information for the Parcel Methodology click on the button Step 4 Define Land Use Conditions from the Catchment Properties Editor This will bring up the Pollutant Source Controls Editor as shown in Figure 6 6 The Area column will be populated based on information entered in the Land Use Editor Pollutant Source Controls Editor Applicable Catchment Catchment ID Catch Area 10ac Road Methodology Road Risk Categories Define Road Area of Land Use Conditions High Moderate Lowy Primary Roads Edit Road Condition Defaults Secondary Roads 40 Edit Road Condition Defaults Parcel Methodology i BMP Implementation Area of Land Use Source No Control BMP BMPs Certificate Certificate Single Family Residential Multi Family Residential CICL vegetated Turf Other Lake Tahoe PLAM v1 0
47. BASIN REPRESENTATION IN PLRM ee eeececeeeeeeeeeeeeeeeees 29 FIGURE 2 17 RECOMMENDED RANGE REPORT vievenssasdvasusedssandeeaedeautedesgusedeudodeertebeviseasies 30 FOURE 2 19 SCENARIO REPOR Dar iso 31 FIGURE 2 19 SCENARIO COMPARISON REPORT ssssssssssessssssesesesessesesssesseeeeeees 32 FIGURE 3 1 gt PROJECT AND SCENARIO EDITOR aaien iae E REEERE 34 FIGURE S 2 PROJEC TEDI TOR uses aaa antes 36 FIGURE 33 SCENARIO EDITO usuarias E its 38 FIGURE 3 4 FINDING PROJECT AND SCENARIO FOLDERS ON YOUR COMPUTER 40 FIGURE 4 1 SCHEMATIC WINDOW AND FUNCTIONS ooococccccccccnccnnnnnnccnnnnnnnnnnnnnnnnnnnnananos 41 FIGURE CATCEHMENT PROPERTIES EDITOR 5d 44 FIGURE3 2 LAND USE EDIPO R oi los bio eel ee 4 FIGURES SOILS EDITOR 0 ti nia 48 FIGURE 6 1 LAND USE CONDITIONS EDITOR ROAD METHODOLOGY 50 FIGURE 6 2 EXAMPLE OF DEFAULT ROAD RISK LAYER ooooooooooocoooooccccncccccnnnnnnononoos 53 FIGURE 6 3 ROAD CONDITIONS EDITOR 0d li a 55 FIGURE 6 4 ROAD SHOULDER CONDITION DECISION PROCESS 58 FIGURE 6 6 LAND USE CONDITIONS EDITOR PARCEL METHODOLOGY 68 FIGURE 7 1 DRAINAGE CONDITIONS EDITOR ROAD METHODOLOGY 71 FIGURE 7 2 ENTERING HYDROLOGIC PROPERTIES FOR A DRAINAGE AREA 76 FIGURE 7 3 SIMPLIFIED IMPERVIOUS AREA CONNECTIVITY DEPICTION T1 FIGURE JAS ACCESS TO HSC FACILITY EDITO Sois id 80 FIGURE 7 53 INFILTRA
48. BLE 10 1 SENSITIVE DEFAULT PARAMETERS WITHIN PLRM DATABASE 117 TABLE 10 2 SENSITIVE INPUT PARAMETERS WITHIN PLRM INTERFACE 119 PLRM User s Manual IV December 2009 List of Abbreviations BMP Best Management Practice CEC Characteristic Effluent Concentration CICU Commercial Institutional Communications Utilities CRC Characteristic Runoff Concentration DIN Dissolved Inorganic Nitrogen FSP Fine Sediment Particles less than 16 microns GIS Geographic Information System GUI Graphical User Interface HSC Hydrologic Source Control HSG Hydrologic Soil Group KML Keyhole Markup Language Ksat Saturated Hydraulic Conductivity PLRM Pollutant Load Reduction Model PSC Pollutant Source Controls SRP Soluble Reactive Phosphorus SWMMS Storm Water Management Model version 5 SWT Storm Water Treatment TMDL Total Maximum Daily Load TN Total Nitrogen TP Total Phosphorus TSS Total Suspended Sediment XML eXtensible Markup Language XSLT eXtensible Stylesheet Language Transformations PLRM User s Manual V December 2009 1 0 Introduction and Overview 1 1 Intended Use of the PLRM The Pollutant Load Reduction Model PLRM 1s intended to be used for evaluating and comparing pollutant load reduction alternatives for storm water quality improvement projects in the Tahoe Basin The PLRM uses publicly available software an
49. Catchment Properties Editor 2 5 Hydrology and Hydrologic Source Controls To enter information on Hydrologic Properties and HSCs click on the button Step 5 Define Drainage Conditions from the Catchment Properties Editor This will bring up the Drainage Conditions Editor as shown in Figure 2 13 There are two tabs on the Drainage Conditions Editor 1 Road Methodology and 2 Parcel Methodology Click on the Road Methodology tab and this will bring up the screen shown in Figure 2 13 Similar to the Land Use Conditions Editor the Drainage Conditions Editor includes an Area column and an Impervious Area column with values populated based on information entered in the Land Use Editor Note that the form will display all available urban land uses for the specific methodology but the Area for land uses that are not defined as present will be zero While the form would allow entry of information for urban land uses not present in the catchment the program would not use the input PLRM User s Manual 24 December 2009 EN Drainage Conditions Editor Catchment 1 Catchi fArea Tac Parcel Methodology Road Methodology Drainage Design Pery Imperr Impery Dep Dep Wo of rea rea DCIA Ksat Storage Storage Primary Roads O acres Area ac ad fin hr in in Area Draining To Infiltration Facilities Edit HSC Facility Edit HSC Facility Secondary Roads 2 acres Edit HSC Facilit Area Draining to Infiltration Faciliti
50. Cs provide a representative estimate of average annual pollutant loading for specific land use conditions Default Parameter parameters necessary fora SWMMS simulation that either do not strongly influence PLRM output e g Manning s n or are typically not project specific e g snowmelt coefficients Parameters that are not directly accessible from the PLRM Interface are termed Default Parameters and are included in the PLRM Database PLRM User s Manual 151 December 2009 Dry Basin a volume based SWT designed to detain runoff for an extended period of time to allow particle and associated pollutant settling Dry basins provide pollutant load reductions from 1 volume reduction via infiltration and 2 improvements in effluent quality relative to influent quality Dry Basins do not have a permanent pool of water they are designed to drain completely between runoff events A Dry Basin is also known as an extended detention basin or dry pond Infiltration Basin a volume based SWT designed to detain and infiltrate storm water runoff Compared to a Dry Basin an Infiltration Basin does not include a treatment outlet that discharges treated storm water as surface flow Infiltration Basins provide pollutant load reductions from volume reductions via infiltration Infiltration Basins are constructed with a highly permeable base to promote infiltration Infiltration Facility distributed infiltration features in a catchment that cou
51. Facility in the PLRM is used to distinguish an HSC that has the functions of either an Infiltration facility or a Pervious Dispersion Area relative to other HSCs activities that can be simulated in the PLRM e g disconnecting or removing impervious area For example decreasing the amount of DCIA is considered an HSC and can be simulated in the PLRM To enter information on hydrologic properties of an HSC Facility click on the button Edit HSC Properties from the Drainage Conditions Editor In the Road Methodology the modeler can edit the properties of an HSC Facility for both an Infiltration Facility and a Pervious Dispersion Area Figure 7 4 In the Parcel Methodology the user can edit properties for an Infiltration Facility Different properties for an HSC facility can be entered and saved for different urban land uses 1 e an Infiltration Facility for Secondary Roads can have different properties relative to an Infiltration Facility for Single Family Residential E Drainage Conditions Editor Catcnent ID Catchy As Accesses Infiltration Facility Editor Figure Parcel Methodology Road Methodology 7 5 of this Manual Drainage Design Impery Dep PRL of Area Area DCIA Ksat Storage Stora Primary Roads 10 acres Area ac ac in hr in in yr Area Draining To Infiltration Facilities 100 0 06 0 1 0 02 Q_ Edit HSC Facility Y Area Draining To Pervious Dispersion Areas 100 0 06 0 1 0 02 Moss a Remaining Area Dr
52. Manual 109 December 2009 The PLRM provides two options for viewing and evaluating results 1 Scenario Report and 2 Scenario Key Concept Box Comparison Report A Scenario Report provides results for the active Scenario in the PLRM The results shown The results shown in the Scenario Report are pollutant loads and not pollutant load reductions Pollutant load in the Scenario Report are pollutant loads and not pollutant load reductions Pollutant load reductions result from comparison of multiple Scenarios within the same reductions result from Project that have completed Scenario Reports The comparison of multiple Scenarios Scenario Comparison Report is used to estimate within the same Project that have pollutant load reductions among multiple Scenarios completed Scenario Reports within the same Project The two reporting options are described below 9 1 Scenario Report To view results for the active Scenario with a completed simulation click on vi iew Report the View Report button on the Schematic Window within the Function eo Toolbar This will bring up the Scenario Report as shown in Figure 9 2 which is organized into four sections Global Information Catchments Storm Water Treatment and Scenario Summary Each section is accessible using the Bookmarks function on the left hand panel of the Scenario Report or by simply scrolling down to the desired section Note that the output in a Scenario Report cannot be edit
53. Pollutant Load Reduction Model PLRM User s Manual December 2009 Terms and Conditions for Use The software product is provided on an as is basis The members of the PLRM Development Team United States Government State of California State of Nevada Northwest Hydraulic Consultants Inc Geosyntec Consultants Inc and 2NDNATURE LLC make no representations or warranties of any kind and specifically disclaim without limitation any implied warranties of title merchantability applicability fitness for a particular purpose and non infringement Although care has been used in preparing the software product the PLRM Development Team members disclaim all liability for its accuracy or completeness and the user shall be solely responsible for the selection use efficiency and suitability of the software product Members of the PLRM Development Team and their agencies officials representatives employees and subcontractors shall not be liable for lost profits or any special incidental or consequential damages arising out of or in connection with use of PLRM regardless of cause including negligence PLRM Development Team members shall have no liability to users for the infringement of proprietary rights by the software product or any portion thereof Any person who uses this product does so at their sole risk and without liability to members of the PLRM Development Team By using this product you voluntarily agree to these terms
54. Project or Scenario to the Project and Scenario Manager The PLRM will provide a default name for a copied Project or Scenario which can be renamed 3 1 Project Editor To create a new Project select the New Project button on the Project and Scenario Manager This will bring up the Project Editor as shown in Figure 3 2 To edit a Project that has already been created double click on the Project name to bring up the Project Editor The following information can be entered in the Project Editor The only required input parameter in the Project Editor is the Project Location Grid No Project Name name of the Project when viewed within the PLRM Interface Changing the name of the Project from the PLRM Interface will not change the default name of the Project Folder on your computer see Section 3 3 EIP Number if applicable where applicable the water quality improvement project s Environmental Improvement Program EIP number s Implementing Agency agency designing and constructing the water quality improvement project Project Location Description location of the water quality improvement project within the Tahoe Basin Where applicable include the Urban Planning Catchment UPC identification PLRM User s Manual 35 December 2009 Eg Project Editor Project Information Project Mame EIP Number if applicable Po Implementing Agency Po Project Location Description PO Project Location Grid No
55. Sub tokals Secondary Road Row Single Family Residential Figure 2 9 Land Use Editor Step 3 Define Soils To enter soil information click on the button Step 3 Define Soils from the Catchment Properties Editor This will bring up the Soils Editor as shown in Figure 2 10 The form is pre populated with all Map Units defined in the 2006 Tahoe Basin Soil Survey NRCS 2006 Identifying the Map Units present in your catchment based on information from the 2006 Tahoe Basin Soil Survey activates an algorithm in the PLRM that will recommend default values for hydrologic properties of soil for the catchment The data source for deriving the soils distribution within a catchment is the 2006 Tahoe Basin Soil Survey which can be downloaded from the NRCS website for Soil Survey Symbol CA693 http soildatamart nrcs usda gov Survey aspx State CA PLRM User s Manual 19 December 2009 The pre populated soils information is organized by Map Unit within the selection box titled Available Map Units To add a Map Unit to the catchment click on the name of the desired Map Unit within the selection box Available Map Units With the soil highlighted click on the Single Arrow button This will transfer the soil to the list box titled Selected Map Units as well as add the soil to the table at the bottom of the form For this example we ll assume a single Map Unit comprises the entire catchment Following the procedure above add Map Unit 717
56. TION FACILITY EDITOR 0 dene a 81 FIGURE 7 6 PERVIOUS DISPERSION AREA EDITOR 00000 ee eecssssssssseeeeeeeeeeseeeeseeeeees 82 FIGURE 5S DRY BASIN EDITOR oia 86 FIGURE 8 2 DRY BASIN REPRESENTATION IN PERM eccccssseseseeeeeeeseeeeeeeeeseees 88 FIGURE 8 3 DRY BASIN VOLUME DISCHARGE CURVE EDITOR eee 89 FIGURE 8 4 INFILTRATION BASIN EDITOR asii dais 90 FIGURE 8 5 INFILTRATION BASIN REPRESENTATION IN PERM oee 91 FIGURE 8 6 INFILTRATION BASIN VOLUME DISCHARGE CURVE EDITOR 93 PLRM User s Manual lil December 2009 FIGURE WETBASIN EDITOR e een SL o 94 FIGURE 8 8 WET BASIN REPRESENTATION IN PLRM ernennen 96 FIGURE 8 9 WET BASIN VOLUME DISCHARGE CURVE EDITOR cenn 97 FIGURE 8 10 BED FILTER EDITOR cc cccccscessssscescesscecsesscsccsscsscsecesscssccsscssesacesscsscsacessesuens 98 FIGURE 8 11 BED FILTER REPRESENTATION IN PLRM ccccccscesccescesscesscesscsscessecseeees 99 FIGURE 8 12 BED FILTER VOLUME DISCHARGE CURVE EDITOR c ccccccssceseeseees 101 FIGURE 8 13 CARTRIDGE FILTER EDITOR ou ccccccccssssscescessesscesscssccsccssessecasessesecseesseeees 102 FIGURE 8 14 CARTRIDGE FILTER REPRESENTATION IN PLRM cccccccessceseeesceseees 103 FIGURE 8 15 TREATMENT VAULT EDITOR ccccccccscssccscessessccsscscccsccsscsscessessessecssessenees 104 FIGURE 8 16 TREATMENT VAULT REPRESENTATION IN PLRM n 105 FIGURE 8 17 OUTFALL EDITOR c
57. Use GIS Layer classifies urban land uses 1 e Single Family Residential Multi Family Residential and CICU as impervious and pervious To populate the Land Use Editor using the TMDL Land Use GIS Layer for these land uses e of Catchment Area tabulate the impervious and pervious area of each land use in GIS and divide by the total catchment area e Impervious divide the impervious area of the land use by the total area of the land use as tabulated in GIS The TMDL Land Use GIS Layer only classifies the impervious area of road land uses 1 e Primary Roads and Secondary Roads and does not provide a method to tabulate the right of way area of road land uses The area within a catchment that is road right of way of Catchment Area field in the Land Use Editor will need to be tabulated in GIS AutoCAD or any other applicable method using a data source other than the TMDL Land Use GIS Layer The Impervious field could be derived using the estimated impervious area of a road land use from the TMDL Land Use GIS Layer and the road right of way area tabulated from other sources PLRM User s Manual 47 December 2009 5 3 Soils Clicking on the button Step 3 Define Soils from within the Catchment Properties Editor will launch the Soils Editor Figure 5 3 This form is pre populated with all Map Units for the Tahoe Basin defined by the 2006 Tahoe Basin Soil Survey NRCS 2006 Defining the Map Units present within a catchment activates
58. Window This will bring up the Dry Basin Editor as shown in Figure 2 15 The first requirement in the Dry Basin Editor is to define the receiving object where surface water leaving the SWT will drain treated and bypassed flows The field Flows to contains a drop down box to select the object that receives flow from the Dry Basin Objects that can receive flow include junctions outfalls dividers or other SWTs Only previously created objects will be available to select from the drop down box For this example select the Outfall you previously created in Key Concept Box the Schematic Window If you didn t rename your Outfall Outfalls are required objects because the PLRM calculates and summarizes average annual runoff volumes and pollutant it will be named Outfall1 in the drop down box Note that Outfalls are required objects in any PLRM simulation because the PLRM calculates and summarizes loading at Outfalls If storm average annual runoff volumes and pollutant loading of a water runoff is not routed to an Scenario at the Outfalls defined for that Scenario If storm Outfall then the Scenario Report water runoff is not routed to Outfalls then the Scenario will not include all runoff and Report Section 9 1 of this Manual will not include all pollutant loading for the runoff and pollutant loading Scenario PLRM User s Manual 27 December 2009 EN Detention Basin Editor A ep N Dry Basins Edit O
59. a source control certificate reduces the CRCs generated from that property BMP Retrofit Certificate a property has completed both PSC implementation i e pervious areas of the property are stabilized and HSC implementation to the typical standard i e storage of runoff from 20 year 1 hour storm on the property Representation in the PLRM Source Control Certificates and BMP Retrofit Certificates signify that PSC implementation has been completed for a certain amount of a particular land use The designation of a Source Control Certificate or BMP Retrofit Certificate will adjust pollutant generation through adjustments to CRCs Table 6 5 to signify that PSCs have been implemented While it 1s recognized that urban land use condition will vary substantially and result in variable CRCs a detailed methodology characterizing parcel condition was not part of the scope of work for PLRM Version Unlike the Road Methodology the Parcel Methodology uses static CRC values that reflect the average condition of a land use based on the presence of PSC implementation or the absence of PSC implementation Table 6 5 displays the default CRCs used by the PLRM and the data sources used to develop the CRCs Table 6 5 is not displayed in PLRM User s Manual 69 December 2009 the Pollutant Source Controls Editor Section 5 2 of the Model Development Documentation provides additional detail regarding development of the Parcel Methodology and the CRCs Ta
60. able the general interactions of the table with the PLRM Interface 3 Reference provides a pointer to additional information about how the data included in the table was developed PLRM User s Manual 136 December 2009 ArealDepletion Description Values in this table are used to specify points on Areal Depletion Curves for both impervious and pervious surfaces Areal depletion refers to the tendency of accumulated snow to melt non uniformly Each curve is defined by 10 equal increments of a relative depth ratio between 0 and 0 9 where a relative depth ratio is an area s current snow depth divided by the depth at which there is 100 areal coverage Structure The table includes two rows that define Areal Depletion Curves separately for impervious and pervious surfaces in 10 equal increments Reference Values in the PLRM Database are default values used by SWMMS for natural areas Additional discussion of Areal Depletion Curves can be found in the SWMM5S User s Manual http www epa gov ednnrmrl models swmm Aquifer Description Values in this table are used calculate transpiration and to define the groundwater elevation at the start of the simulation Structure The table includes one row and a number of columns organized to inform the SWMMS5 code for Aquifers A number of fields are blank in the table because an algorithm is used to populate the fields based on the meteorological grid cell the user defines in the Project Editor
61. aining To Outlet 40 0 06 0 1 0 02 Secondary Roads O acres Area Draining to Infiltration Facilities q Area Draining To Pervious Dispersion Areas A l Remaining Area Draining To Outlet Accesses Pervious Dispersion Area Editor Figure 7 6 of this Manual Lake Tahoe PLRM v1 0 Figure 7 4 Access to HSC Facility Editors PLRM User s Manual 80 December 2009 7 3 1 Infiltration Facility Editor Figure 7 5 displays the Infiltration Facility Editor accessed from the Drainage Conditions Editor EN Infiltration Facility Editor Em lx Hydrologic Properties of HSC Receiving Runoff Infiltration Facilities Storage Default Units Value Unit Area Storage in 1 Saturated Hydraulic Conductivity infhr 0 50 Figure 7 5 Infiltration Facility Editor Two Input Parameters can be adjusted for an Infiltration Facility PLRM Unit Area Storage defined as the depth of precipitation over the impervious drainage area which an Infiltration Facility 1s sized to store Current TRPA regulations require containment of the storm water runoff volume generated by a 20 year return period 1 hour duration design storm from impervious surfaces The calculation of runoff volume is made by multiplying the precipitation depth taken as one inch of precipitation in one hour by the impervious surface area The default value in the Infiltration Facility Editor is set to 1 inch reflecting the TRPA
62. all runoff and pollutant loading for that Scenario PLRM User s Manual 149 December 2009 Sequence of Data Entry in Catchment Properties Editor The sequence of data entry within the Catchment Properties Editor is forced by the PLRM because input data in subsequent steps 1s contingent upon input data entered in previous steps If you complete data entry in the Catchment Properties Editor but then decide to go back and edit one of the intermediate steps e g edit land uses in Step 2 the PLRM will require you to reconfirm data entered for subsequent steps Note that 1f you find the OK button 1s not active on the Catchment Properties Editor but all five steps appear active as shown this means you need to reenter Step 5 Define Drainage Conditions and reconfirm input data for that step After reconfirming input data in Step 5 the OK button will be active and the PLRM will allow you to exit the Catchment Properties Editor with the edits saved PLRM User s Manual 150 December 2009 12 2 Definitions of Terms Bed Filter a flow based SWT designed for vertical filtration of storm water through a porous medium such as sand compost zeolite or combinations of natural and engineered substrates Bed filters provide pollutant load reductions by removing particulates and associated pollutants from storm water through physical straining and adsorption Some storage 1s typically designed above the media bed that temporarily ponds storm water when t
63. alue for the Drainage Conditions Area Draining to Infiltration Facilities and Remaining Area Draining to Outlet This is automatically done for each land use based on user entered information in the Land Use Conditions Editor for BMP Retrofit Certificates By definition a BMP Retrofit Certificate indicates impervious area on a parcel that is routed to an Infiltration Facility For each Urban Land Use in the Parcel Methodology the of Area value that the user entered for BMP Retrofit Certificates is therefore the value used in the Drainage Conditions Editor for the Drainage Area Area Draining to Infiltration Areas The remaining area is automatically calculated by the PLRM and input into the Drainage Area Remaining Area Draining to Outlet PLRM User s Manual 74 December 2009 7 2 Hydrologic Properties of Land Uses For each Drainage Condition within a land use the Drainage Conditions Editor will suggest Input Parameters for hydrologic properties that most strongly influence calculations of surface runoff in the PLRM The following provides a description of each Input Parameter The most sensitive Input Parameter accessible from the Drainage Conditions Editor is the percentage of the impervious area that 1s directly connected to the drainage system termed directly connected impervious area DCIA Section 10 2 provides additional guidance for the Input Parameters described below DCIA The percentage of impervious area that is
64. ameter Depression Storage Storage of precipitation provided through ponding surface wetting and interception on pervious surfaces Section 10 2 of this Manual provides guidance on selecting a value for pervious depression storage based on the characteristics of the pervious area The default value for a Pervious Dispersion Area is 0 2 inches A value close to 0 1 should be used for pervious areas without significant vegetation or forest cover A value closer to 0 2 should be used for areas with thick vegetative cover or a forest litter layer In PLRM Version 1 defining a Pervious Dispersion Area will add area to the simulation above that specified by the user in the Land Use Editor Depending on the size of the Pervious Dispersion Area this could cause a notable discrepancy in output After adding a Pervious Dispersion Area the user should return to the Land Use Editor and subtract out the area from the associated land use that comprises the Pervious Dispersion Area A future version of the PLRM may develop a more automated method to address this discrepancy PLRM User s Manual 83 Key Concept Box A Pervious Dispersion Area will add area above that specified by the user in the Land Use Editor After adding a Pervious Dispersion Area the user should return to the Land Use Editor and subtract out the area from the associated land use that comprises the Pervious Dispersion Area December 2009 8 0 Defining Storm Water Tr
65. an algorithm in the PLRM that will recommend default values for hydrologic properties of soil for the catchment The recommended default values can be reviewed and edited by the user in Step 5 Define Drainage Conditions EW Soil Editor Soil Type Distribution Available Map Units Selected Map Units 7151 Jorge very cobbly fine sandy loam 5 to 15 percent A 7171 Kneeridge gravelly sandy loam 2 to 9 per 7152 Jorge very cobbly fine sandy loam 15 to 30 percen 7153 Jorge very cobbly fine sandy loam 30 to 50 percen 7154 Jorge very cobbly loam 2 to 15 percent slopes ext 7155 Jorge very cobbly loam 15 to 50 percent slopes e 7156 Jorge Tahoma complex 15 to 30 percent slopes 7157 Jorge Tahoma complex 30 to 50 percent slopes 7161 Kingsbeach stony sandy loam 2 to 15 percent slope 7172 Kneeridge gravelly sandy loam well drained 5 to 15 y Map Unit of Catchment Area Sub totals DO 7171 Kneeridge gravelly sandy loam 2 to 9 percent slopes extremely stony 00 Lake Tahoe PLRM v1 0 Figure 5 3 Soils Editor The pre populated soils information is organized by Map Unit within the selection box titled Available Map Units To add a Map Unit to the catchment click on the name of the desired Map Unit within the selection box Available Map Units With the soil highlighted click on the Single Arrow button This will transfer the soil to the list box titled Selected Map Units as well as add soil to
66. annel was not deemed to be effective at stabilizing a road shoulder then the user could classify that particular road shoulder as not stable PLRM User s Manual 61 December 2009 Example 1 Erodible Photos 1 and 2 below are examples of Erodible road shoulders The designation was determined based on answers to the following two questions Be OO RIG vay te Ak GOmue Photo 1 Erodible Photo 2 Erodible Question 1 Could storm water runoff collect along the road shoulder and cause erosion YES not stable runoff could collect and erode the pervious shoulders Note that the road shoulders in the photos may be disconnected from the drainage system However as discussed in various places in this document the connectivity of impervious area is not used to judge the condition of road shoulders for pollutant generation Therefore the road shoulders should be designated as Erodible in the examples above because runoff will collect in the unpaved portion of the road shoulder and could erode the shoulder Question 2 Can automobiles and or snow plow activity disturb a significant portion of the unpaved road shoulder YES not protected the majority of the unpaved pervious right of way can be disturbed Determination Erodible PLRM User s Manual 62 December 2009 Example 2 Protected Photo 3 below shows an example of a Protected road shoulder The designation was determined based on answers to the follow
67. antly altered the hydrologic properties of the soil The recommended range was developed based on analysis of the 2006 NRCS Tahoe Basin Soil Survey Survey Technical documentation regarding how the PLRM provides a suggested default value for Ksat is included in the PLRM Technical Development Document Section 4 1 The user may override the suggested value for Ksat for each urban land use The user should justify overriding suggested values for Ksat based on site specific information or site specific measurements that may have been collected during the Existing Conditions Analysis The PLRM simulates runoff and pollutant loading individually from specific urban land uses e g Single Family Residential within a user defined catchment The estimate of Ksat should be characteristic of the pervious areas associated with the specific land use within the user defined catchment If a specific land use has significantly dissimilar hydrologic properties of soil dispersed in different areas within the catchment the user may want to consider splitting the catchment into two separate catchments 125 December 2009 Pervious Depression Storage Flagged As Range Message Reference Guidance Warning Low 0 1 inches High 0 2 inches Depression storage 1s used to simulate the storage of precipitation provided through ponding surface wetting and interception Pervious depression storage below the recommended minimum may be to
68. asin volume 2500 2500 Footprint of Filter 1000 1000 Filtration Rate 1 1 Oc here fo see schenatic wit parameter gegooi Characteristic Effluent Concentration Pollutants of Concern Default value User value Figure 8 10 Bed Filter Editor Lake Tahoe PLRM v1 0 PLRM User s Manual 98 December 2009 The following are data entry fields for a Bed Filter e Name edit the default name of the Bed Filter if desired By default the PLRM will name Bed Filters in a Scenario sequentially as BedFilter BedFilter2 etc e Flows to contains a drop down box to select the object that receives flow from the Bed Filter Objects that can receive flow include junctions outfalls dividers or another SWT Only previously created objects in the Schematic Window will be available to select from the drop down box Design Parameters The Bed Filter Editor requires entry of key Design Parameters to simulate the performance of the Bed Filter for capturing and treating storm water runoff Key Design Parameters include e Equalization Basin Volume cf the storage volume above the surface of the bed filter e Footprint of Filter sf surface area of the Bed Filter e Filtration Rate in hr the average rate of flow through the filter media The filtration rate times the footprint of the filter 1s the average treatment flow rate cfs An illustration of how the Design Parameters relate to the conceptual repres
69. bject Mame DryBasin1 Flows To Qutfall1 w Design Parameters Custom volume Discharge Curve Parameters Default Value User Value Water Quality Volume 2500 3000 Footprint 1000 000 Infiltration Rate 0 2 0 0 Brim Full Draw Down Time 60 Te CHA ere to see schenatic with parameter Descuidos Characteristic EMuent Concentration Pollutants of Concern Default value lUser value 25 25 25 25 dal 1 1 0 16 Lake Tahoe PLAM v1 0 Figure 2 15 Dry Basin Editor The Dry Basin Editor requires entry of key Design Parameters to simulate the performance of the Dry Basin for capturing and treating runoff Key Design Parameters include e Water Quality Volume storage capacity below the bypass outlet designed for water quality treatment e Footprint surface area that will typically be inundated approximately the area at the average design depth e Infiltration Rate characteristic rate of infiltration expected over the life span of the SWT while factoring in assumptions for anticipated or committed maintenance PLRM User s Manual 28 December 2009 e Brim Full Draw Down Time time it takes for the Water Quality Volume to completely drain through treatment outlets s as treated storm water runoff without consideration of the infiltration rate An illustration of how the Design Parameters relate to the representation of a Dry Basin in the PLRM is accessible from the Dry Basin Editor by clicking on Click here to see
70. ble 6 5 Parcel CRCs With and Without PSCs Parcel Land Use Condition CRC Values mg L unless otherwise noted a Data Source Poe ween iS Type by mass SS MEE Yume 20 3 36 1 752 0 144 0 468 0 144 Conditions Values With PSCs TMDL Tier 1 Values 14 0 36 1 577 0 421 With P TMDL Existi tilo xisting 150 87 0 58 2 844 0 42 0 588 0 144 Conditions Values With PSCs TMDL Tier 1 Values 32 7 58 0 378 0 529 With P TMDL Existi os xisting 206 4 186 7 63 2 472 0 293 0 702 Conditions Values CICU With PSCs TMDL Tier 1 Values 128 5 63 2 136 0 195 0 536 Without PSCs nutrient values from 2NDNATURE 2007 o Sei eats valine 12 4 3 36 4 387 0 547 1 09 0 631 Existing Conditions Veg_ Turf With PSCs nutrient values from 2NDNATURE 2007 sediment 12 4 3 36 2 369 0 319 0 454 0 289 values from TMDL Tier 1 Unlike Source Control Certificates which signify that only PSC implementation was completed BMP Retrofit Certificates signify that HSC implementation has been completed with PSC implementation In addition to assigning the CRCs shown in Table 6 5 to the area designated as having BMP Retrofit Certificates storm water runoff from that area will be routed to an HSC in the PLRM to retain and infiltrate the runoff The details of how the HSC operation works in the PLRM are discussed in Section 7 2 of this Manual PLRM User s Manual 70 December 2009 7 0 Defining Hydrology
71. cal terms a High Risk Road relative to a Moderate Risk Road is 1 steeper 2 has higher average traffic volumes and or 3 has denser urban land uses adjacent to the road Conversely a Low Risk Road relative to a Moderate Risk Road is 1 flatter 2 has lower average traffic volumes and or 3 has less dense urban land uses adjacent to the road PLRM User s Manual 52 December 2009 Legend High Risk Primary Road Moderate Risk Primary Road Low Risk Primary Road High Risk Secondary Road Moderate Risk Secondary Road Low Risk Secondary Road Figure 6 2 Example of Default Road Risk Layer PLRM User s Manual 53 December 2009 Table 6 1 outlines the criteria used to create the Basin wide default urban Road Risk GIS Layer available with the PLRM executable Figure 6 2 You can adjust the Road Risk for specific road segments in your catchment 1f you believe the actual Road Risk 1s not adequately defined by the criteria outlined in Table 6 1 or 1f they are not accurately reflected in the default GIS layer Remember that the definition of Road Risk 1s not influenced by the connectivity of impervious area to downstream receiving waters You should not revise Road Risk based on considerations for impervious area connectivity as this characteristic is an input of the Drainage Conditions Editor Section 7 of this Manual Adjusted Road Risk should reflect the relative risk to produce high medium or low CRCs based solely on physiographic condi
72. cccccccssessceccessessccccesscsscccesscsscsaccsscssecacesseessessecscesseseeeees 106 FIGURE 8 18 JUNCTION EDITOR 0 cccccccessceccessesscccccssesscccesscsscseccsecsscacesseessessesecasessenees 107 FIGURE 8 19 FLOW DIVIDER EDITOR c ccccccscsscescessesscessessccscesscssccsccsscssecasessessecssessenees 108 FIGURE 9 1 RECOMMENDED RANGE REPORT ccccsssccssessesscescessesecessessecssessessceseessenees 109 FIGURE 9 2 SCENARIO REPORT cccccccessessccccescesscsecessesscsseesscsscsacssscsseacessecseessessecsseasenees 111 FIGURE 9 3 SCENARIO COMPARISON REPORT cccssessessesscescesscsccsscsccssessesscessessenees 114 FIGURE 11 1 SIMPLIFIED IMPERVIOUS AREA CONNECTIVITY DEPICTION 124 FIGURE 11 1 PLRM DATABASE AND PROGRAM STRUCTURE nern 136 List of Tables TABLE 1 1 DESCRIPTION OF PLRM DOCUMENTATION cccccssesscescescessccscesscsseeseessenees 2 TABLE 6 1 CRITERIA FOR DEFAULT ROAD RISK GIS LAYER rennen 54 TABLE 6 2 ROAD ABRASIVE APPLICATION STRATEGIES erren 56 TABLE 6 3 ROAD SHOULDER CONDITIONS INPUT cccccsssescessesseescessesccssessesscessesseees 58 TABLE 6 4 SWEEPER TYPE ccccccccsccssessccccessesscstcessesscscesscsscacesscsscsaecseeesssssessccsesssesacesseaseess 66 TABLE 6 5 PARCEL CRCS WITH AND WITHOUT PSCS ccccccscssccccessesseescessessecscessesseees 70 TABLE 7 1 DEFAULT PERCENT DCIA VALUES ccccccccccocsessssscessesscessessescesscssescessesseens 78 TA
73. cenario Comparison Report location where pollutant load reductions for a Project can be calculated among Scenarios with completed simulations o Scenario Report provides summary results for a single Scenario after a simulation has been completed for that Scenario O e View Toolbar Contains buttons to adjust the view in the Schematic Window and select objects The function of each button is as follows Resize and view multiple windows Select objects referred to as the Selection Tool in this Manual Select objects in a defined area ar Zoom in Zoom out HLS Zoom to extents Adding Objects from the Object Toolbar To add an object from the Object Toolbar make sure the Selection Tool is active and click on the desired object The cursor will change to an icon that resembles cross hairs Move the cross hair cursor into the white space on the Schematic Window and click once The object you selected from the Object Toolbar should appear To add additional objects select the next object you would like to add from the Object Toolbar and repeat the process When all objects have been created click on the Selection Tool within the View Toolbar to close the session for adding objects Moving Objects To move an object after 1t has been added to the Schematic Window make sure the Selection Tool is active Left click once on the object near its center A blinking square will appear inside the obje
74. cesescess 4 1 5 INSTALLING AND RUNNING THE PROGRAM cscceccscsceccececcscscesceccscesceceecscectecesceseecescseces 7 ZO OUICK START GUIDE Sonia aa li 9 2 1 STARTING A NEW PROJECT AND SCENARIDO ccccccccececcececcececcccecesescecescecsescsescesesceceseeceses 10 2 7 DEV ECOPINGA SCHEMA TIC e e ee a bel ete neonate 14 2 9 ENTERING CATCAMENTIODA TA ia 16 2 4 LAND USE CONDITIONS AND POLLUTANT SOURCE CONTROLS ccescececcsceccececescecesceceses 21 2 5 HYDROLOGY AND HYDROLOGIC SOURCE CONTROLS c cecescecescecscsceccscscecescecescecseecuses 24 JO STORM WATER REATMENT Sess eeccte ued estar sshia vate ous ied treo ue uate bet ec see aubecasiaws A riaa 27 2 7 RUNNING THE MODEL AND VIEWING RESULTS cecccceccececccceccscccecescecscscesescecescecesesceces 30 3 0 WORKING WITH PROJECTS AND SCENARIOS 1z ccecccccccccccccccccccccccccccces 34 ils Fede Vi eM ON te ot ee ade ae cto da e o 35 DZS CEN AR EDITOR oto oie a dae betcha ee east 37 3 3 MANAGING PROJECTS AND SCENARIOS ON YOUR COMPUTER cscecescececcececcececescecescececes 39 4 0 DEVELOPING A SCHEMATIC wicca cccccasersctccseeeccckscacelacasccecdesedealacdoncssseveockecucdualecavesdesevcones 41 5 0 ENTERING CATCHMENT DATA ada 44 SEPH SIC ALT RT WS aeaa a T 45 A A a O IN 46 ES 1S A et ote as ae erg tbe ene IA RP A en EOD ro PE tae ere IO 48 6 0 DEFINING LAND USE CONDITIONS AND POLLUTANT SOURCE CONTROLS 50 OL ROADIMETAODOLOS Vi O e O e so
75. cific Project and Scenario When a user creates a new Project a Project Folder is created in the Projects Directory When a user creates a new Scenario a Scenario Folder is created and placed in the associated Project Folder Project and Scenario Folders are named sequentially by the PLRM e g Project1 Project2 Scenariol Scenario2 etc and should never be moved or renamed from Windows Explorer Within the PLRM Interface a Project or Scenario can be renamed using the Project and Scenario Editors This will create an alias for the Project or Scenario when viewed within the PLRM Interface However it will not rename a Project or Scenario Folder on your computer PLRM User s Manual 39 December 2009 The directory structure on your computer for Project and Scenario Folders uses the default naming convention of the PLRM for file management purposes If you rename a Project or Scenario to create an alias name in the Project and Scenario Editors the Project and Scenario Manager Figure 3 4 provides a function to show you the pathname to the files on your computer When you click on a Project or Scenario 1t will be highlighted and the location of the associated Project Folder or Scenario Folder will be shown at the bottom of Project and Scenario Manager In the example shown in Figure 3 4 the Project with the alias HSC Test can be found in the folder C PLRM Project Project1 If you want to delete or view individual files created fo
76. cococococococococososososococococococococosocosocecoso 116 10 1 DEFAULT PARAMETERS iia 117 LO INPUT PARAMETERS dernire o tee ees 118 11 0 PLRM DATABASE OVERVIEW 00 is 135 12 0 NOTES ON PLRM MODELING esesesesesecesecesescocococcecesecesecscocococococococococococococosocosocososo 147 12 1 LIMITATIONS AND STRUCTURE OF VERSION 1 ccceccsceccscececcececescscscscecescecescecesceceses 147 12 2 DEFINITIONS OF TERMS a a aes do 151 PLRM User s Manual il December 2009 List of Figures HGOURE1L MODELINOS APPROACH siii 5 FIGURE 2 iP IIR VNC ON e T R 9 FIGURE 22 STARTING THE PER Miri a a S 10 FOURE 2 3 PROJECTED OR e ud 11 FIGURE 2 4 PROJECT AND SCENARIO MANAGER ssssssssssesssessseseeseeeseseeseseeess 12 PIGURE 253 SCENARIO EDITOR rror n A EE de dese 13 FIGURE 2 6 SCHEMATIC WINDOW AND FUNCTIONS onnccccccocconcccocccncccocconococcconccccocoocnoos 15 FIGURE 2 7 QUICK START EXAMPLE ELEMENTS ias 16 FIGURE 2 8 CATCHMENT PROPERTIES EDITOR sonscntiio nati 17 FIGURE 29 AND USE PDIO Ro ee ee 19 FIGURE 21050 TiS EDOR ni ies ao e a 20 FIGURE 2 11 LAND USE CONDITIONS EDITOR iwecsinnsswetanputsnerandvatesepanadeapessanesndvetecepuseddisics 21 FIGURE 2 P2 ROAD CONDITIONS EDITOR cia 23 FIGURE 2 13 DRAINAGE CONDITIONS EDITOR ROAD METHODOLOGY 25 FIGURE 2 14 DRAINAGE CONDITIONS EDITOR PARCEL METHODOLOGY 26 FIGURE 2 15 DRY BASIN EDITOR vests eters ei eer 28 FIGURE 2 16 DRY
77. cription of each field and each row used to populate the SWMM5 code can be reviewed by opening the table in Design View in Access Reference See Section 4 3 of the Model Development Document Soils Description This table includes hydrologic properties of soil for each Map Unit from the 2006 NRCS Tahoe Basin Soil Survey Survey Structure Available soils by Map Unit in the Soils Editor are populated from this table Additionally this table is used to generate recommended values for Ksat that appear in the Drainage Conditions Editor The following are functions of key columns in the table e MU unique identifier for the Map Unit as defined by the Survey e HydSoilGroupID the dominant hydrologic soil group of the Map Unit This value is related to the table HydSoilGroup to supply Soil Suction Head to the SWMMS5 code for the Green Ampt equation e KsatPervoius value taken from the Survey for saturated hydraulic conductivity Ksat of the Map Unit in units of inches hour e SoilMoisDef initial soil moisture deficit of the Map Unit value is used in the Green Amp equation in SWMMS5 e MUName long description of the Map Unit Reference See Section 4 1 of the Model Development Document Sweeping Effectiveness Description This table provides default values that estimate the effectiveness of pollutant recovery through street sweeping by sweeper type and sweeping frequency Structure The Road Conditions Editor interacts dynamica
78. ct 1t may take a few attempts to find the location of the blinking square for _ Blinking Square PLRM User s Manual 42 December 2009 different objects Left click again on the blinking square and hold the left click button You should now be able to move the object by moving your mouse Deleting Objects To delete an object after it has been added to the Schematic Window make sure the Selection Tool is active Left click once on the object near its center A blinking square will appear inside the object 1t may take a few attempts to find the location of the blinking square for different objects Hit the Delete button on your keyboard The PLRM will ask you to confirm the deletion of the object Select YES to delete the object and NO to cancel Accessing Input Forms for Objects To access Input Forms for each object after 1t has been added to the Schematic Window double click on the object In most cases you can double click anywhere on the object to bring up the relevant Input Form Defining Storm Water Routing Between Objects Storm water routing between objects 1s not defined from the Schematic Window but rather from within the individual Input Forms For each object there 1s drop down box titled Flows to that will include all other objects that have been added to the Schematic Window that can receive flow Objects that can receive flow include junctions outfalls dividers or other SWTs Examples of objects t
79. ctiveness Volume of surface runoff and seasonal timing of runoff Volume of surface runoff and the estimate of evapotranspiration relative to infiltration Volume of surface runoff Pollutant loads generated December 2009 10 2 Input Parameters Table 10 2 below describes the most sensitive Input Parameters included in the PLRM Interface including a description of each parameter the specific form where they can be found in the PLRM Interface and a brief description of how each Input Parameter influences PLRM output Table 10 2 also provides the minimum and maximum recommended ranges for each Input Parameter When the user enters a value outside the recommended ranges shown in Table 10 2 the user entered value will be flagged by the program and will be included in the output report titled Recommended Range Report The Recommended Range Report provides a brief message regarding any suggested actions for any value entered by the user that 1s flagged as being outside the recommended range Three descriptions are used in the Recommended Range Report to categorize values entered by the user that have been flagged A value flagged by the Recommended Range Report does not necessarily mean the value entered by the user 1s incorrect 1 Note An action by the user is not likely required as values outside the recommended range commonly occur However given the sensitivity of the input parameter a value outside the recommended range is fla
80. cts and the Scenarios associated with each Project using a tree structure For the Project you just created click once on the plus sign next to the name of the Project to expand the tree structure You ll see that the PLRM automatically created your first Scenario when you created the Project with the default name Scenario1 Depending on whether you edited the name of your Project in the Project Editor the form should look like Figure 2 4 PLRM User s Manual 11 December 2009 ES Project and Scenario Manager Double Click on a Project Scenario to Begin Copy Selected Scenariol New Project Project or Scenario Files at C Program Files PLRM Projects Project1 Lake Tahoe PLRM v1 0 Figure 2 4 Project and Scenario Manager To start working with a Scenario double click on the default Scenario1 created by the PLRM for your Project In this example the Scenario is named Scenario1 This will bring up the Scenario Editor as shown in Figure 2 5 PLRM User s Manual 12 December 2009 Ea Scenario Editor Project Information EIP Number if applicable Po Implementing Agency AAA Project Location Description A Project Location Grid No Continous simulation Length Short Simulation Scenario Information Working Directory Scenario Mame Scenario Lake Tahoe FLAM v1 0 Figure 2 5 Scenario Editor The program does not require you to enter information in the Scenario E
81. d Available Scenarios and Results 2 In the drop down box titled Step 2 Select Baseline Scenario select Scenario1 This will be the baseline Scenario typically the existing condition to which other Scenarios will be compared for calculating pollutant load reductions 3 Inthe selection box titled Available Scenarios and Results click on Scenario2 to highlight it Then click on the Single Arrow button pointing to the list box titled Compared to Baseline This will move Scenario2 into the list box and populate the tables below Completing the steps above will populate the pollutant load reductions tables in the Scenario Comparison Report as shown in Figure 2 19 Two tables are provided in the Scenario Comparison Report that report 1 average annual loads and 2 the relative difference of pollutant loads among Scenarios To export the output in this form to an editable format click on the button Export and specify the location for saving the file PLRM User s Manual 33 December 2009 3 0 Working with Projects and Scenarios When you first start the PLRM you will see the Project and Scenario Manager as shown in Figure 3 1 The Project and Scenario Manager creates copies and organizes Projects and Scenarios In PLRM terminology Projects and Scenarios are defined as follows Project a set of analyses within the PLRM used to compare existing or proposed storm water conditions to predict potential pollutant load reducti
82. d source code to provide users with complete access to the tools developed The PLRM is intended to be practical for application by users possessing a basic understanding of hydrology water quality and water resources modeling The PLRM provides predictions of storm water pollutant loads on an average annual basis for urbanized areas within the Tahoe Basin The PLRM reports an average annual mass of pollutants of concern and an average annual runoff volume The primary purpose of the PLRM is to assist project designers to select and justify a recommended storm water project alternative based on a quantitative comparison of pollutant loads and runoff volumes for project alternatives Pollutant loads in storm water are highly variable and notoriously difficult to predict with absolute accuracy at particular locations and times The focus of the PLRM is to make use of best available Lake Tahoe storm water quality information to compare relative performance of Key Concept Box alternatives over the long term _ There are no restrictions to the size of a catchment that can be The recommended spatial scale of application for the modeled However if you model PLRM is the typical Tahoe Basin storm water quality catchments that are smaller or improvement project scale i e roughly 10 100 acres larger than the recommended There are no restrictions in the PLRM on the size of a size scale roughly 10 100 acres you should first review Section 1
83. detailed tabulation in GIS or AutoCAD The intent of the methods is to reasonably estimate the general Road Methodology characteristics of storm water For the Road Methodology three types of Drainage routing within a catchment by Conditions are defined for each Road Land Use Primary land use Roads and Secondary Roads The user specifies the of or 100 of Secondary Roads within the catchment drain to infiltration facilities Area in each Drainage Condition in the Drainage Conditions Editor Drainage Conditions in the Road Methodology are defined as follows e Area Draining to Infiltration Facilities the impervious portion of a road land use within the catchment routed to an Infiltration Facility An Infiltration Facility could be a dry well an infiltration trench or any other physical structure designed to store and infiltrate runoff e Area Draining to Pervious Dispersion Areas the impervious portion of a road land use within the catchment routed to a pervious surface for dispersal and infiltration of runoff A Pervious Dispersion Area is typically not the pervious portion of the right of way but rather an urban lot or collection of urban lots where storm water is dispersed Representing impervious pervious connectivity of the pervious portion of the right of way is defined by specifying Directly Connected Impervious Area DCIA discussed in Section 7 2 of this Manual e Remaining Area Draining to the Outlet th
84. directly connected to the drainage system DCIA can significantly affect runoff volumes and pollutant loading This is a key Input Parameter in the PLRM that can significantly influence results and care should be taken when estimating this value However the intent of the PLRM and the Formulating and Evaluating Alternatives FEA process in general avoids recommending overly cumbersome techniques for estimating DCIA as the quantification of DCIA is recognized to be somewhat subjective The amount of time allocated for estimating the DCIA for input into the Drainage Conditions Editor should be limited to the time Key Concept Box DCIA can significantly influence results and care should be taken when estimating this Input Parameter However the quantification of DCIA is recognized to be somewhat subjective The amount of time allocated for estimating the DCIA for input into the Drainage Conditions Editor should be limited to the time needed to gain confidence that the estimated value is reasonably accurate needed to gain confidence that the estimated value is reasonably accurate for each Drainage Condition In general estimation closer than about 10 may provide diminished returns in modeling results relative to the time it takes to gain such accuracy e g 1s the impervious area of a land use routing type 0 20 40 60 80 or 100 directly connected A project that decreases DCIA in a catchment will reduce runoff
85. ditor to proceed Primarily you can use this form to edit the name of your Scenario in the field Scenario Name The users name and Scenario notes may also be entered into the form for future reference Click the Next button to begin building a PLRM Scenario using the Schematic Window After clicking the Next button a message will pop up that explains that the long term meteorological data for the selected grid cell needs to be created This operation will take up to five minutes depending on the speed of your computer The operation will not be repeated again as long as you don t change the meteorological grid cell for your Project Click the OK button on the message and in about five minutes the PLRM will complete the meteorological data extraction operation and the Schematic Window will become active PLRM User s Manual 13 December 2009 2 2 Developing a Schematic The Schematic Window is the central input form for the PLRM and allows the modeler to complete the following functions e Create a visual representation of their Scenario e Define model elements and drainage routing between model elements e Access input forms for Catchments and SWT s that are created e Run a simulation for a single Scenario e View results for a single Scenario or compare the results for multiple Scenarios The Schematic Window will appear as shown in Figure 2 6 for a new Scenario Figure 2 6 provides a brief overview of the functions of the buttons on the
86. down box to select the object that receives flow from the Catchment Objects that can receive flow include junctions outfalls dividers or SWTs Only previously created objects in the Schematic Window will be available to select from the drop down box e Area catchment area units in acres e Slope average slope of the catchment enter slope in units of percent e g a catchment with an average slope of 5 5 2 Land Uses Clicking on the button Step 2 Define Land Uses from within the Catchment Properties Editor will launch the Land Use Editor Figure 5 2 This form is pre populated with Tahoe Basin land uses as defined by the Lake Tahoe TMDL program The pre populated land uses are selectable from the box titled Available Land Uses To add a land use to the catchment click on the name of the desired land use within the selection box Available Land Uses With the desired land use highlighted click on the Single Arrow button This will transfer the selected land use to the list box titled Selected Land Uses as well as add the land use to the Land Use Table at the bottom of the form To complete the Land Use Table the PLRM needs to know the following for each land use defined as present in the catchment e of Catchment Area the percentage of the catchment occupied by the land use The sum of land use percentages for the catchment should add up to 100 in the Sub totals row of the table e Impervious the percent imp
87. e e Wet Pool Volume cf the wet pool water quality volume used for flow through treatment The wet pool can be depleted by evaporation and is regenerated by incoming flows e Wet Pool Footprint sf surface area of the wet pool which affects the rate of evaporation from the wet pool surface e Minimum Hydraulic Residence Time HRT of Wet Pool hr the minimum travel time of a parcel of water entering the wet pool for which effective water quality treatment would occur The wet pool volume divided by the minimum HRT is used to compute the wet pool treatment flow rate The recommended range is 24 to 96 hours e Surcharge Basin Volume cf the water quality storage volume above the wet pool This parameter is used for hybrid Wet Basins that include both retention and detention storage The surcharge basin volume is not flood control storage e Brim Full Draw Down Time hr time it takes for the Surcharge Basin Volume to completely drain through treatment outlet s The recommended range is 48 72 hours An illustration of how the Design Parameters relate to the conceptual representation of a Wet Basin in the PLRM is accessible from the Wet Basin Editor by clicking on the link Click here to see schematic with parameters descriptions Clicking on the link will bring up Figure 8 8 PLRM User s Manual 95 December 2009 Wet Pool Volume Surcharge Basin Volume O gt Minimum HAT Brim Full I
88. e for future model development PLRM User s Manual 2 December 2009 1 3 User s Manual Content The User s Manual is the primary document describing how to apply the PLRM The manual is organized into the following sections A hyperlink to each section in this Manual is provided below To use the hyperlink function hold the CTRL button on your keyboard and click on a hyperlink e Section 1 Introduction and Overview Describes the intended uses of the PLRM provides an overview of the modeling approach provides guidance on how to install and run the program and describes the typical data needs and sources for obtaining necessary data e Section 2 Quick Start Guide Describes how to use the PLRM in a brief step by step procedure e Section 3 Working With Projects and Scenarios Describes the file management structure of the PLRM and the relationship of projects and scenarios e Section 4 Developing a Schematic Describes how to build a scenario using the PLRM graphical user interface GUI as well as how to link graphical elements together to define storm water routing within a scenario e Section 3 Entering Catchment Data Describes how to enter catchment data for key physiographic parameters land uses and soils e Section 6 Defining Land Use Conditions and Pollutant Source Controls Describes the PLRM Road Methodology and Parcel Methodology which are used to estimate characteristic runoff concentration
89. e impervious portion of a road land use within the catchment not routed to an HSC Facility prior to reaching the catchment outlet An HSC Facility is either an Infiltration Facility or a Pervious Dispersion Area PLRM User s Manual 73 December 2009 Parcel Methodology The tab in the Parcel Methodology in the Drainage Conditions Editor is similar to the Road Methodology except the Parcel Methodology does not include an option to specify a Drainage Conditions for Area Draining to Pervious Dispersion Areas Representation of impervious pervious connectivity for urban land uses included in the Parcel Methodology is defined by specifying Directly Connected Impervious Area DCIA discussed in Section 7 2 of this Manual Urban Land Uses in the Parcel Methodology include Single Family Residential Multi Family Residential CICU and Vegetated Turf Drainage Conditions in the Parcel Methodology are defined as follows e Area Draining to Infiltration Facilities the impervious portion of an urban land use within the catchment routed to an Infiltration Facility An Infiltration Facility could be a dry well an infiltration trench or any other physical structure designed to store and infiltrate runoff e Remaining Area Draining to the Outlet the impervious portion of an urban land use within the catchment not routed to an Infiltration Facility prior to the catchment outlet In the Parcel Methodology the PLRM automatically inputs the of Area v
90. e information as shown in Figure 2 12 Note how the CRCs dynamically change for each Road Risk category as information about the Pollutant Potential and Street Sweeping activities are entered After completing data entry in the Road Conditions Editor to match Figure 2 12 select the OK button to save the information close the form and return to the Pollutant Source Controls Editor Figure 2 11 Parcel Methodology The Parcel Methodology defines the amount of private property BMP implementation for each urban land use present in the catchment BMP implementation is entered in the Pollutant Source Controls Editor in the table titled BMP Implementation as the percent of area of the land use There are two types of BMP Implementation as defined by TRPA which issues BMP certificates Source Control Certificate a property has completed PSC implementation 1 e pervious areas of the property are stabilized However the property has recognized constraints that do not allow for HSC implementation to the typical standard 1 e storage of runoff from 20 year 1 hour storm on the property BMP Retrofit Certificate a property has completed both PSC and HSC implementation to the typical standard For this example we ll assume that the Single Family Residential land use has 25 of its total area under BMP Certificate compliance Enter the information to reproduce Figure 2 11 then Click the OK button to save the information entered and return to the
91. eas Existing condition DCIA is highly variable 50 was selected Remaining Area for the default but the user should always confirm or edit Draining to the 50 the default value based on an understanding of their Outlet catchment and drainage characteristics Results can be very sensitive to this Input Parameter Ksat inch hour Infiltration over pervious areas is simulated using the Green Ampt equation and values for saturated hydraulic conductivity Ksat are the most sensitive input parameter for the equation The PLRM provides a suggested value for Ksat in the Drainage Conditions Editor that applies to the pervious area of each land use The suggested value is based on user input in the Soils Editor as well as a number of algorithms that are described in detail in Section 4 1 of the Model Development Document The basis for developing the suggested value for Ksat provided in the Drainage Conditions Editor is the following 1 The user inputs the distribution of soils in their catchment using the Map Units defined by the 2006 NRCS Tahoe Basin Soil Survey Survey 2 The PLRM calculates an area weighted value for Ksat in the catchment based on the hydrologic properties of the Map Units as defined in the Survey 3 A compaction factor is applied to the area weighted Ksat value to incorporate the likely impact of urbanization on infiltration Compaction factors vary among urban land uses where land uses judged to typically decrease inf
92. eatment Facilities and Objects There are a number of Storm Water Treatment SWT facilities than can be simulated in the PLRM A hyperlink to guidance describing each SWT as well as the other PLRM objects junctions outfalls and dividers is provided below To use the hyperlink function hold the CTRL button on your keyboard and click on a hyperlink e Dry Basins e Infiltration Basins e Wet Basins e Bed Filters e Cartridge Filters e Treatment Vaults or User Defined SWT e Junctions Outfalls and Flow Dividers The reduction in pollutant loading achieved by a SWT facility depends on the portion of runoff treated and the extent of treatment achieved The PLRM estimates pollutant load reductions achieved by an SWT facility using basic design information supplied by the user and a long term simulation of hydrology to continuously compute hydraulic capture for the SWT Runoff captured by the SWT is considered treated and is assigned a characteristic effluent concentration CEC for pollutants of concern that is specific to each SWT facility Runoff that is not captured by the SWT is considered untreated or bypassed and is assigned an effluent concentration equaling the influent concentration Pollutant loads can be reduced in a SWT facility through reductions in storm water volumes and or improvements in storm water quality Both processes are controlled by the hydraulic capture of the SWT i e the percent of the runoff volume captured a
93. ective The recommended level of effort for the Road Methodology is to designate the dominant road shoulder condition by block 1 e one designation for every 500 foot segment of road In many cases the left and right road shoulder conditions may vary markedly for the same block If this occurs the user should define the dominant road shoulder condition for the left and right shoulder of the same block The user can choose to define road condition at a finer or coarser scale of spatial resolution 1f increased resolution 1s thought to significantly improve results In particular the user may find it useful to define a finer scale of spatial resolution for High Risk and Moderate Risk road shoulders because these Road Risk Categories will likely have highest pollutant loads and therefore will be targeted for water quality improvements e Relationship to Impervious Area Connectivity This section provides guidance on estimating road shoulder condition as 1t relates to pollutant generation and PSC implementation As mentioned above impervious area connectivity is not a consideration for judging the condition of the road shoulder for pollutant generation For example a disconnected compacted dirt road shoulder should not be defined as stable because one might assume that storm water runoff does not reach a storm water inlet or piping system Using the PLRM methodology a disconnected compacted dirt road shoulder should be defined as erodible in the Road
94. ects on roads to store less than the 20 year 1 hour storm volume because of constraints in road rights of way that limit storage opportunities 128 December 2009 Infiltration in a Dry Basin Flagged As Warming Range Low 0 05 in hour High 0 5 in hour Message Infiltration in a dry basin is calculated based on the infiltration rate of the Dry Basin and the footprint of the Dry Basin Unlike pervious drainage areas and HSCs infiltration in a Dry Basin is not calculated based on Ksat but is directly specified by the user as an infiltration rate An infiltration rate below the minimum recommended range indicates that a Dry Basin is not functioning for infiltration Similar to HSCs an infiltration rate above the maximum recommended range should be justified as a hydraulically loaded Dry Basin may not perform above the recommended maximum over the long term simulation 18 years without significant maintenance Reference The recommended range was developed based on analysis of literature values that relate Hydrologic Soil Group HSG to Ksat NRCS 2007 While it is recognized that HSG does not directly correlate to the long term performance of a Dry Basin for infiltration the relationship was used to conservatively bound expected performance Sensitivity tests show that values above the recommended range strongly influence results and may result in overly optimistic estimates of long term load reductions Guidance The PLRM pr
95. ed in the Moderate and Low columns see Key Concept Box After completing the Road Risk input we ll move on to defining the condition of the Secondary Roads within the catchment Select the button Edit Road Conditions Defaults to bring up the Road Conditions Editor as shown in Figure 2 12 Make sure you select the button for Secondary Roads and not the button for Primary Roads PLRM User s Manual 22 Key Concept Box The PLRM code was written to ensure percentages in tables add up to 100 Fields with text in blue with a shaded background are not editable and are calculated based on information entered in other associated fields For example in the Road Risk table the value for High is calculated as 100 minus value in Moderate column minus value in Low column December 2009 E Road Conditions Editor ce s ha Pollutant Potential Road Shoulder Conditions Percent Pollutant Road Abrasive Eradible Protected Stable Stable and Potential Road Risk Application Strategy Protected Score Minimal control measures High ka Moderate Minimal control measures e e Low Minimal control measures Sweeping Effectiveness Sweeping Effectiveness Road Risk Type of Sweeper Sweeping Frequency Score High Regenerative Air wt Winter 0 times Summer 1 2 times wt 2 Moderate Regenerative Air e Winker 0 times Summer 1 2 times w a 1 0 Low Mechanical Broom Winter 0 times Summer 1 2 times bl
96. ed or copied from a i Export Report E the PLRM Interface To copy or compare output in a Scenario Report it must first be exported by clicking on the Export Report button on the Function Toolbar in the Schematic Window This option allows the user to define a location on their computer where a Scenario Report will be exported in a format that can be viewed copied and edited using any text editor The Export Report button will export the Scenario Report for the active Scenario in the PLRM PLRM User s Manual 110 December 2009 EN Lake Tahoe PLRM v1 0 Project Name Project1 Scenario Name TestRoads Status Report Project Manager 443 Save El Run A Compare Scenarios li View Report P xport Report g About A h rr A im ES Status Re port Bookmarks Global Information Catchments Storm Water Treats Projecti Scenario Summary s 6 C Program Files PLRM Projects Projecti1 Scenarioi 10 15 2009 11 27 33 10 15 2009 11 57 31 amp LEO OO e El Volume ac ft yr TSS lbs yr FSP lbs yr TP lbs yr SRP lbs yr TN lbs yr DIN lbs yr 40615 70 acre feet fyr Total Precipitation Evaporation Loss 6 33 System Surface Discharge 14 67 Percolation to Groundwater 7 29 Continuity Error 0 55 Percent Surface Runoff 52 15 Average Annual Surface Loading TSS lbs yr ESP lbs yr TP lbs yr SRP lbs yr TN lbs yr DIN lbs yr Outfalli 54488 78 40608 06 Scenario Total 14 67 54488 78 40608 06 81
97. eeuts 51 OL LORA TASK COTE COTE EEA ci DZ 6 1 2 Road CONAItIONS cccccccccuccccccecccoccececucaccccecscnscececscnccsceuscscscccesesscnsesesuscsseseeescscesesesesces 55 02 PARCEL METHODOLOGY siria E TE EE a E a eee 68 7 0 DEFINING HYDROLOGY AND HYDROLOGIC SOURCE CONTROLS 71 7 1 DRAINAGE CONDITIONS lt A ein ithe Son hei ees 73 7 2 HYDROLOGIC PROPERTIES OF LAND USES ccececcecececccecececececescscecececescecscncesescecnceeuecs 75 7 3 HYDROLOGIC PROPERTIES OF HSC FACILITIES ccceccscececcececcccecscscsesceccscecescecesesceses 80 PILAR UTE ON EF A CUNETA A A 8l J Dice POVOS DISDCTSLOMPATCA E QU OF ssn E AO OO 82 8 0 DEFINING STORM WATER TREATMENT FACILITIES AND OBJECTS o o 84 S LDORY BAS A A A A A 86 8 2 INFILTRATION BAS IN aaa 90 PLRM User s Manual December 2009 SW ET BASIN ilatina oa ee cle tia aaa e a ie elle nia oa da cal stress 94 SADO arses se o erotic t ios aid 98 0 CARTRIDO ES FILIE ta o a a a a a O 102 8 6 TREATMENT VAULT OR USER DEFINED FLOW BASED SWT cceccececececcccececscsceees 104 8 7 OUTFALLS JUNCTIONS AND FLOW DIVIDERS ccecceccecceccecceccsccsccscescescescescescescetceecs 106 9 0 RUNNING THE MODEL AND VIEWING RESULTS u ccccccccccccccccccceces 109 9 SCENARIO REPOR cc henets oso korea o Lee de Achaea aie 110 0 SCENARIO C OMPARISON REPORT ad Dias 114 10 0 PARAMETER GUIDANCE sesesesecesecesececececeoeccococc
98. entation of a Bed Filter in the PLRM is accessible from the Bed Filter Editor by clicking on the link Click here to see schematic with parameters descriptions Clicking on the link will bring up Figure 8 11 E y ji F r A f f f F 5 i j r j f f j f 4 i 7 Fi 7 A n f J i i f f Y i f i i 5 4 ri f f H 4 5 i H f i f i F 7 F f d i j f i s f F i j i A j f s 7 f s g A y s Inflow e gee ot ot tts es O AAA cono e 0 A A EEPE TE RES mos At A A AA to e ors 0 90 wee gt 0590 wee e o otoo e oes ot ere ee Se IAS AA IA AA pa T ri oe o 7 eRe te er 7s o atajo o RA AE 5 y steets San an RA A o A Se ae a o AAA A A AAA PA 6 7 gt te atte o a3 ee o AAA AAA RO AAA YAA AO AAA ra PA AA O PARA N e ey 0 Mo Fe ya 0 8 86 0 re x hd SAO Y IAEA AAA ee or rr rr rr or 9 tee 9 9 0 o r rr oro ae a Pe a oo AAA errors oF evagtes lt 0 B a OO AT Sea PAPA et et we ee et th ee ee oe E oot eth we gece t att ee eet at thet eee A A b A c oraotostoge METER Me st Doe wee II ME fe Media Filter Rate Treated Flow gt Figure 8 11 Bed Filter Representation in PLRM
99. epings 4 Frequent Winter twice monthly summer 1 2 times assume roads well swept prior to first fall rain 12 annual sweepings 5 Very Frequent Winter as soon as possible after abrasive application summer monthly assume roads well swept prior to first fall rain 24 annual sweepings PLRM User s Manual 66 December 2009 6 1 2 3 Characteristic Runoff Concentrations CRCs The condition of roads within a catchment is correlated to characteristic runoff concentrations CRCs to estimate average pollutant generation A CRC is a representative concentration for a pollutant of concern in runoff from a specific Road Land Use Road Risk Category and associated condition When combined with continuous runoff hydrology from the PLRM CRCs are intended to provide a representative estimate of average annual pollutant loading for specific land use conditions CRCs are automatically calculated within the Road Conditions Editor for each Road Risk Category as information is entered for Pollutant Potential and Sweeping Effectiveness CRCs are calculated for all pollutants of concern which include e TSS Total Suspended Sediment e FSP Fine Sediment Particles TSS less than 16 microns in diameter e TP Total Phosphorus e SRP Soluble Reactive Phosphorus e TN Total Nitrogen e DIN Dissolved Inorganic Nitrogen The research and development that went in to relating Pollutant Potential and Sweeping Effectiveness to CRCs fo
100. er s Manual 76 December 2009 Figure 7 3 below 1s taken directly from the Interim Guidance Paper However the complete guidance for estimating DCIA as described in the Interim Guidance Paper is not repeated here Directly Connected Impervious Area DCIA impervious surfaces draining to a conveyance system Area A in Figure 7 3 Indirectly Connected Impervious Area ICIA impervious surfaces draining to pervious surfaces that promote infiltration distribution and energy dissipation or storage prior to overflow draining to a conveyance system Area B in Figure 7 3 Figure 7 3 Simplified Impervious Area Connectivity Depiction Table 7 1 displays the defaults for DCIA in the Drainage Conditions Editor by Drainage Area PLRM User s Manual 77 December 2009 Table 7 1 Default Percent DCIA Values Default 9 l RRA DER s Rationale for Default and Sensitivity of Value _ Impervious area routed to an HSC facility is typically directly PEA Preinine ye l 100 connected to the HSC facility and the default was set to Infiltration Facilities 100 For example 1 a roof draining to a drip line trench 2 a driveway draining to a dry well or 3 a road with curb and gutter routed to an urban lot Because the area is Area Draining to routed to an HSC the calculations of surface runoff at the Pervious Dispersion 100 catchment outlet will have minimal sensitivity to the Areas selection of the DCIA for these Drainage Ar
101. er s Manual for a description of the various analysis options for a SWMMS simulation ParcelCRCs Description This table includes characteristic runoff concentrations CRCs for pollutants of concern for all land uses not incorporated into the Road Methodology which is all land uses in the Parcel Methodology as well as all Erosion Potential land uses Structure This table provides CRCs to the SWWM5 code for all land uses except Road Land Uses including Urban Land Uses with BMPs implemented A description of each field can be reviewed by opening the table in Design View in Access The following are functions of key columns in the table e code value in the Codes table for land uses e Pollutant_Code value in the Codes table for pollutant of concern e Land_Use abbreviation used in XML code to generate a SWMMS input file e Pollutant abbreviation for pollutant of concern e Function SWWMS analysis option always EMC e Coeffl CRC for land use and pollutant of concern in units of mg L Reference See Section 5 2 of the Model Development Document Pollutants Description This table defines pollutants of concern simulated by the PLRM Structure The table includes a number of required fields needed by the SWMM5 code to define each pollutant of concern A description of each field can be reviewed by opening the table in Design View in Access Reference See Section 5 2 of the Model Development Document PLRM U
102. erage and average precipitation In most cases the Short Simulation will produce output with similar results to a Full Simulation Once the Scenarios have been developed and quality assured the user should switch to the Full Simulation option to assess and report output Save Project Info Saves information entered in the Project Editor and returns to the Project and Scenario Manager 3 2 Scenario Editor The Project and Scenario Manager organizes Projects and the Scenarios associated with each Project using a tree structure The PLRM will automatically create the first Scenario for a Project with the default name Scenariol If Scenarios are not visible in the Project and Scenario Manager click once on the plus sign next to the name of the applicable Project to expand the tree structure To create a new Scenario for the Project with the Project highlighted click on the New Scenario button in the Project and Scenario Manager You can access the Scenario Editor Figure 3 3 by either creating a new Scenario or double clicking on an existing Scenario The PLRM does not require you to enter information in the PLRM User s Manual 37 December 2009 Scenario Editor to proceed to the Schematic Window The Project Information box in the Scenario Editor is provided for information purposes and can only be edited from the Project Editor The Scenario Information box allows you to enter and edit the following information Created By the pe
103. ervious area within each land use The PLRM provides a default estimate of percent impervious area for each land use However this value should be changed or confirmed by the user for each specific catchment because impervious area can significantly affect surface runoff in a catchment The PLRM will calculate the average percent imperviousness for the entire catchment in the Sub totals row based on user entry for percent imperviousness of individual land uses e Acres The PLRM automatically calculates the area of each land use from the of Catchment Area field and the total area of the catchment entered in Step 1 The recommended data source for deriving the land use distribution within a catchment is the TMDL Land Use GIS Layer which can be downloaded from the Lahontan LRWOCB website http www waterboards ca gov lahontan water_issues programs tmdl lake_tahoe index shtml PLRM User s Manual 46 December 2009 Ee Land Use Editor Catchment Land Uses tchi f Area Jacy Available Land Uses Selected Land Uses vegetated Burned Secondary Road ROW Unpaved Road Single Family Residential Ski Run Erosion Potential 1 Erosion Potential 2 Erosion Potential 3 Erosion Potential 4 Erosion Potential 5 v Land Use of Catchment Area Impervious Sub totals 100 00 148 0 Secondary Road ROW 20 80 Single Family Residential sol 40 Lake Tahoe PLRM v1 0 Figure 5 2 Land Use Editor The TMDL Land
104. es _ Edit HSC Faciity_ Area Draining To Pervious Dispersion Areas Edit HSC Facility Remaining Area Draining To Outlet Lake Tahoe FLAM 1 0 Figure 2 13 Drainage Conditions Editor Road Methodology For the Road Methodology three drainage areas can be defined for each road land use e Area Draining to Infiltration Facilities e Area Draining to Pervious Dispersion Areas e Remaining Area Draining to the Outlet The user specifies the of Area that comprises each drainage area within a road land use For each drainage area the Drainage Conditions Editor will suggest input parameters for drainage characteristics that most strongly influence calculations of surface runoff in the PLRM The most sensitive input parameter is the percentage of the impervious area within a drainage area column titled Imperv Area ac that is directly connected to the drainage system column titled DCIA The DCIA value should be changed or confirmed by the user for each drainage area because DCIA can significantly affect surface runoff PLRM User s Manual 25 December 2009 For this example we ll assume that HSCs have not been implemented and the entire Secondary Road land use drains to the outlet Remaining Area Draining to Outlet 100 We ll also assume that the impervious area associated with the roads in the catchment is roughly 50 directly connected to the outlet DCIA 50 Note that these assumptions are the default values for the
105. filtration Basin for capturing and infiltrating storm water runoff Key Design Parameters include e Water Quality Volume cf storage capacity below the bypass outlet designed for infiltration e Footprint sf surface area that will typically be inundated approximately the area at the average design depth e Infiltration Rate in hr characteristic rate of infiltration expected over the life span of the SWT while factoring in assumptions for anticipated or committed maintenance The recommended range is 0 5 1 5 inches hour and the default value is inch hour An illustration of how the Design Parameters relate to the conceptual representation of an Infiltration Basin in the PLRM is accessible from the Infiltration Basin Editor by clicking on the link Click here to see schematic with parameters descriptions Clicking on the link will bring up Figure 8 5 5 As i 4 f f A 0 P 7 f F Y Pi f f f i i i ee f i j i i f f l i j 0 p r il p j j j q f j d i Y j JE r y Fi H s Inflow Flow Infiltration Rate Figure 8 5 Infiltration Basin Representation in PLRM PLRM User s Manual 91 December 2009 Pollutant load reductions from Infiltration Basins in the PLRM are a function of volume losses via infiltration of the Water Ouality Volume The volume of infiltrated storm water as well as an estimate of pollutant load removed from
106. gged by the program for review by the user 2 Warning Action by the user 1s likely required as values outside the recommended range are not typical In certain instances values outside the recommended range are allowable However in these instances the warning message signifies that the user should provide a rationale for selection of a value outside the recommended range e g pollutant delivery factors not equal to 1 3 Error Action by the user is required as data input will result in model instabilities and or erroneous results For each input parameter identified in Table 10 2 additional guidance not found in the Recommended Range Report is provided below regarding the 1 Message significance of being outside the recommended range 2 Reference brief description of how the recommended range was developed and 3 Guidance discussion on the level of effort for estimating an input parameter and or additional guidance regarding how to estimate the input parameter PLRM User s Manual 118 December 2009 Table 10 2 Sensitive Input Parameters within PLRM Interface Inout Parameter Mecenotion Location in A ni a Influence on PLRM P j PLRM Interface Output Used to explicitly vary CECs for Pollutant pollutant source controls not directly Road Conditions Pollutant loads ratio Delivery Factors accounted for in the Road Editor generated from roads Methodology A Maximum elevation minimum Catchment 1 30 P elevatio
107. hat cannot receive flow include 1 any Catchment or 2 any object cannot be routed to itself The user should first add all objects envisioned for a Scenario to the Schematic Window then define storm water routing of individual objects from the Input Forms This approach will ensure that all potential objects that could receive flow are accessible from each Input Form when defining storm water routing PLRM User s Manual 43 Key Concept Box The routing between objects is not defined from the Schematic Window but rather from within the individual Input Forms for each object using a drop down box titled Flows to The user should first add objects envisioned for a Scenario to the Schematic Window then define storm water routing using Input Forms December 2009 5 0 Entering Catchment Data To access the Catchment Properties Editor add a Catchment to the Schematic Window and double click on the catchment icon The Catchment Properties Editor requires entry of catchment information in a series of steps Information entered from one step 1s used to populate recommended default parameters and inputs parameters in subsequent steps Thus the steps must be completed sequentially When you first access the Catchment Properties Editor Figure 5 1 some steps will not be active and cannot be selected The sequence of data entry is forced by the PLRM because input data in subsequent steps is contingent upon input data entered in previ
108. he best available long term continuous precipitation data included in the PLRM is at hourly intervals from the SnoTel gages The use of 1 hour interval precipitation data may not represent peak flows that would be expected from short duration high intensity precipitation c Flow based SWT facilities in the PLRM require the user to define a maximum treatment rate runoff above the maximum treatment rate will bypass the SWT and be considered untreated The PLRM may overestimate performance of flow based SWT facilities in small catchments because the hourly interval precipitation data may cause peak flows to be under predicted during high intensity events User s Manual 147 December 2009 d The sensitivity of potential errors was tested on a limited basis using a data set of sub hourly precipitation compared to hourly precipitation available from the Lake Tahoe Airport The sensitivity testing showed a negligible difference in the long term average annual capture ratio for flow based SWT facilities for catchments within the recommended size range for the PLRM This result is due to longer times of concentration for larger catchments and the infrequent nature of the high intensity precipitation events 1 e summer thunderstorms which have a relatively small contribution to the overall water balance in the Tahoe Basin for any given water year However as catchment size decreases below the recommended range precipitation intensity will become a
109. he rate of inflowing storm water 1s greater than the rate of filtration through the media Treated storm water is collected in an underdrain system and routed as surface flow Cartridge Filter a flow based SWT that typically houses a number of proprietary cartridges that contain engineered filtration media Cartridge filters provide pollutant load reductions by removing particulates and associated pollutants from storm water through physical straining and adsorption While some storage is often provided within the vaults that house the cartridge filters the SWT facility is typically designed as a flow through device and storage 1s considered negligible Characteristic Effluent Concentration CEC represents the effluent concentration typically achieved by a SWT facility Water quality improvement attributed to the treatment of storm water in a SWT is modeled by applying CECs to the volume of runoff captured that exits the treatment outlet s of a SWT facility The current default CEC values are based on best available data and were derived from statistical analysis of multiple storm water performance studies to predict a representative level of treatment for each SWT facility for the pollutants of concern Characteristic Runoff Concentration CRC a representative concentration for a pollutant of concern in runoff from a specific land use and associated land use condition When integrated with continuous runoff hydrology from the PLRM CR
110. hough land uses may be spatially distributed throughout the catchment The intent of the PLRM and the Formulating and Evaluating Alternatives FEA process is not to require overly cumbersome techniques for estimating DCIA the quantification of DCIA is recognized as being somewhat subjective The amount of time allocated for this effort should be limited to the time needed to gain confidence that the estimated DCIA 1s reasonably accurate for each land use within a catchment An estimate to the nearest 10 will normally be sufficient If a specific land use has dramatically dissimilar percentages of DCIA dispersed in different areas within the catchment the user may want to consider splitting the catchment into two separate catchments PLRM User s Manual 124 December 2009 Ksat for a Pervious Drainage Area Flagged As Range Message Reference Guidance PLRM User s Manual Note Low 0 05 in hour High 3 in hour Infiltration over pervious areas is simulated using the Green Ampt equation and values for saturated hydraulic conductivity Ksat are the most sensitive input parameter for the equation Ksat values above the maximum recommended range are not uncommon for Tahoe Basin soils However values above the recommended range indicate that the pervious area has relatively undisturbed hydrologic characteristics In other words values above the recommended range indicate that urban land use activities have not signific
111. hours 1t takes for the user specified water quality volume of an SWT to completely drain through treatment outlet s as treated storm water runoff A constant discharge rate 1s used in the PLRM for the entire volume unless the user specifies a custom volume discharge curve See Section 9 Runoff leaving a SWT through treatment outlets 1s assigned a Characteristic Effluent Concentration CEC for each pollutant of concern Values below the recommended minimum drain time are not suggested because the modeling approach assumes a relatively long hydraulic residence time 1s needed to produce the default CECs used in the PLRM Values above the recommended maximum are acceptable for water quality performance but may conflict with mosquito concerns vector control requirements which typically require ponded water to drain in 72 hours The recommended minimum drain time of 48 hours was selected to be consistent with assumptions for default CECs in PLRM and to avoid user input that might over predict actual SWT performance see Guidance below The California Stormwater BMP Handbook for New Development and Redevelopment January 2003 recommends a minimum drain time of 48 hours and cautions against a drain time of more than 72 hours because of vector control concerns The recommended range for drain time is relatively narrow The minimum drain time of 48 hours reduces the potential for performance in volume based SWT s to be over predicted CEC values fo
112. ic conductivity Ksat are the most sensitive input parameter for the equation Ksat below the minimum recommended range indicates the HSC is not functioning for infiltration Ksat values above the maximum recommended range should be justified as a hydraulically loaded HSC may not perform above the recommended maximum over the long term simulation 18 years without significant maintenance The recommended range was developed based on analysis of literature values that relate Hydrologic Soil Group HSG to Ksat NRCS 2007 While it 1s recognized that HSG does not directly correlate to the long term performance of an HSC the relationship was used to conservatively bound expected performance Sensitivity tests show that values above the recommended range strongly influence results and may result in overly optimistic estimates of long term load reductions The PLRM provides a conservative estimate of the characteristic long term performance of infiltration in a HSC When modifying the suggested default value outside the recommended range the user should ensure that a characteristic value is estimated and not an optimal value A characteristic value is defined as the average expected condition of the HSC over the life span of the HSC while factoring in assumptions for anticipated or committed maintenance NRCS U S Department of Agriculture 2007 National Engineering Handbook Part 630 Hydrology Chapter 7 Hydrologic Soil Groups PLRM
113. ided within the vaults that house the cartridge filters the SWT facility is typically designed as a flow through device and storage is considered negligible To access the Cartridge Filter Editor add a Cartridge Filter to the Schematic 38 Window and double click on the Cartridge Filter icon This will bring up the mm Cartridge Filter Editor as shown in Figure 8 13 En Cartridge Filter Editor Cartridge Filters Edit Object Name CartridgeFilter 1 Flows To Design Parameters Parameters Default Value User Value Maximum Treatment Flow 0 O Gok mere lo see schematic Wih parameter Desonbtions Characteristic Effluent Concentration Pollutants of Concern Default Value User Value 13 13 13 13 ei 1 5 Lake Tahoe PLAM v1 0 Figure 8 13 Cartridge Filter Editor PLRM User s Manual 102 December 2009 The following are data entry fields for a Cartridge Filter e Name edit the default name of the Cartridge Filter if desired By default the PLRM will name Cartridge Filters in a Scenario sequentially as CartridgeFilter 1 CartridgeFilter2 etc e Flows to contains a drop down box to select the object that receives flow from the Cartridge Filter Objects that can receive flow include junctions outfalls dividers or another SWT Only previously created objects in the Schematic Window will be available to select from the drop down box Design Parameters The Cartridge Filter Editor requires entry of a single key De
114. idered Treated Flow The quality of Treated Flow is assigned CECs for pollutants of concern as defined in the Dry Basin Editor Storm water that bypasses the Dry Basin through the bypass outlet when the Water Quality Volume is exceeded is considered Bypass Flow The quality of Bypass Flow is equal to the influent concentration of the storm water entering the Dry Basin The Dry Basin Editor allows for modification of default CEC values but any modification should be justified by the user Customized Treatment Rate and Infiltration Rate The Dry Basin Editor provides a function that allows the user to customize the Treatment Rate and Infiltration Rate of a Dry Basin as a function of the Water Quality Volume to account for complex outlet designs head dependent infiltration rates or variable stage area relationships This function can be accessed by clicking on the Custom Volume Discharge Curve button from the Dry Basin Editor Figure 8 1 Clicking on the button will activate the Volume Discharge Curve Editor Figure 8 3 The column Volume ft divides the user defined Water Quality Volume entered in the Dry Basin Editor into ten increments For each increment the user can set the Treatment Rate cfs and Infiltration Rate in hr of the Dry Basin The Treatment Rate cfs 1s surface runoff that drains through the treatment outlet s of the Dry Basin The following functions can be performed from the Volume Discharge Curve Editor e Save and Close
115. iltration in pervious areas the most have the highest compaction factors From highest to lowest compaction factors are ranked as follows Primary Roads Secondary Roads CICU Multi Family Residential Single Family Residential PLRM User s Manual 78 December 2009 The user may override the suggested value for Ksat for each urban land use or for a specific Drainage Condition within a land use in the Drainage Conditions Editor The user should base adjustments to Ksat on site specific information that may have been collected during an Existing Conditions Analysis or field reconnaissance and ensure that it represents anticipated long term performance Pervious Depression Storage inch Pervious depression storage accounts for the storage of precipitation on pervious surfaces caused by ponding surface wetting and interception The default value in the PLRM is 0 1 inches A value close to 0 1 should be used for pervious areas without significant vegetation or forest cover A value closer to 0 2 should be used for areas with thick vegetative cover or a forest litter layer Impervious Depression Storage inch Impervious depression storage accounts for the storage of precipitation on impervious surfaces caused by ponding surface wetting and interception The default value of 0 05 inches is recommended for use without modification PLRM User s Manual 79 December 2009 7 3 Hydrologic Properties of HSC Facilities The term HSC
116. in centralized BMPs Figure 1 1 Modeling Approach The following discussion highlights the modeling capabilities for the PLRM organized into sections representing the PLRM Interface and each element of the pollutant load simulation 1 e HSC PSC and SWT PLRM Interface The following are current capabilities of the PLRM Interface e Simple and intuitive data entry architecture e Graphic representation of a project area e Multiple catchment simulation e Pre processed Tahoe specific input data and default input parameters that facilitate ease of use and consistency e Flexibility for user override of default input parameters e Summarized output for hydrology pollutant loading and storm water treatment e Comparison of multiple scenarios to compute pollutant load reductions e Automated flagging and reporting of user variations outside recommended ranges for sensitive input parameters PLRM User s Manual 5 December 2009 Hydrology and Hydrologic Source Controls HSC Hydrologic simulations in the PLRM include the following capabilities e Snowfall and snowmelt e Effects of directly and indirectly connected impervious area including routing directly connected areas to pervious areas e Private property BMP implementation e Infiltration and evapotranspiration including accounting and reporting of volumes For the hydrologic computations in the PLRM pre processed input data sets and default input parameters are provided
117. in the PLRM Database Structure This is the primary table used to define a new field for land uses pollutants of concern SWT facilities etc The following are functions of the columns in the table e code value used by the PLRM Database to define a field e name name of field e PLRM_Name abbreviation used in XML code to generate a SWMM5 input file e description describes how a specific code fits within a family of codes Reference None cited this is the internal reference table for the PLRM Database Defaults Description The table includes various defaults used in the PLRM Interface and some values used by database algorithms This table also includes land use specific compaction factors used in the algorithm that generates recommended values for Ksat that appear in the Drainage Conditions Editor Land use specific compaction factors have IDs in the 700s for this table Structure The following are functions of key columns in this table e defaultValue the value used by the PLRM Interface for a specific variable e description a brief description of where the default value is used e variable a brief description of the variable Reference See Section 10 2 of this Manual for a discussion on the various default values See Section 4 1 of the Model Development Document for discussion on how compaction factors are applied to generate recommended Ksat values PLRM User s Manual 138 December 2009 Evaporation Descr
118. increases the potential for scour and pollutant transport e Traffic Density Highly trafficked roads receive more frequent road abrasive applications and are subject to increased road shoulder disturbance through human and vehicle traffic Sediment on highly trafficked roads will be subject to more pulverization and therefore a higher fraction of FSP is anticipated in storm water runoff e Adjacent Land Use Roads adjacent to denser urban land uses e g Commercial and Multi Family Residential tend to have more frequent road abrasive applications and are subject to increased road shoulder disturbance through human and vehicle traffic Figure 6 2 displays the default Road Risk GIS Layer developed from these parameters for use in the PLRM You can use the default Road Risk Layer in GIS to develop an estimated distribution of Road Risk Categories in your catchment for Primary and Secondary Roads The default Road Risk GIS Layer is available for download along with the PLRM setup program and documentation from http www tims org TIIMS Sub Sites PLRM aspx Road Risk can be defined separately for Primary Roads and Secondary Roads in the Land Use Conditions Editor Figure 6 1 The distribution of Road Risk is entered as percentages of the total road land use i e Primary Roads or Secondary Roads using categories of High Risk Moderate Risk and Low Risk The sum of percentages for the three Road Risk Categories should equate to 100 In practi
119. ing two questions Photo 3 Protected Question 1 Could storm water runoff collect along the road shoulder and cause erosion YES not stable runoff will convey along the unpaved portion of the shoulder between the pavement and vegetation Question 2 Can automobiles and or snow plow activity disturb a significant portion of the unpaved road shoulder NO protected the vegetation indicates that parking and snowplow disturbance does not occur for a significant portion of the unpaved road shoulder within the right of way although a user must judge if this condition can be reasonably expected in future Determination Protected PLRM User s Manual 63 December 2009 Example 3 Stable Photo 4 below shows an example of a Stable road shoulder The designation was determined based on answers to the following two questions Ste Photo 4 Stable Photo 5 Stable Question 1 Could storm water runoff collect along the road shoulder and cause erosion NO stable conveyance is stabilized by the rolled curb and gutter Question 2 Can automobiles and or snow plow activity disturb a significant portion of the unpaved road shoulder YES not protected the rolled curb and gutter will not deter parking in the unpaved area of the road shoulder within the right of way behind the curb and gutter Determination Stable PLRM User s Manual 64 December 2009 Example 2 Stable and Protected Photos 6 7
120. ion of FSP and phosphorous Note Reductions in Measures overall road abrasive applications have occurred in most jurisdictions across the Basin in the last several years These reductions are not assumed to meet the definition of moderate or advanced control measures Alternative deicing strategies such as brine pre application are employed to Measures reduce the frequency and quantity of road abrasive applications Alternative deicing strategies are used in combination with advanced management measures such as temperature sensors or meteorological monitoring to minimize road abrasive applications based on antecedent conditions and storm types Also if there is a section of road that does not receive any abrasive application it should be specified as this strategy Advanced Control Measures 6 1 2 1 2 Road Shoulder Conditions The following key points should be kept in mind when estimating road shoulder conditions e Recommended Level of Effort The intent of the PLRM is not to require overly burdensome methods for estimating road shoulder conditions The amount of time allocated for this effort should be limited to the time needed to gain confidence that the estimated road shoulder conditions are reasonably accurate on a catchment scale Road shoulder conditions can be highly variable within neighborhoods and even between PLRM User s Manual 56 December 2009 individual houses Determining road shoulder condition is somewhat subj
121. ious area to be almost entirely disconnected 1 e lt 10 DCIA When a user enters a value that is above the recommended maximum the user has defined the impervious are to be almost entirely connected 1 e gt 80 DCIA The most current guidance for estimating the percentage of DCIA is found in Interim Guidance Paper for Formulating and Evaluating Alternatives for Tahoe Basin Water Quality Improvement Projects 2008 That Interim Guidance Paper can be downloaded at http www trpa org default aspx tabindex 44tabid 168 Figure 11 1 below is taken directly from the Interim Guidance Paper However the complete guidance for estimating DCIA as described in the Interim Guidance Paper is not repeated here Directly Connected Impervious Area DCIA impervious surfaces draining to conveyance systems via a hydraulic connection Area A in Figure 11 1 Indirectly Connected Impervious Area ICIA impervious surfaces draining to pervious surfaces that promote infiltration distribution and energy dissipation or storage prior to overflow draining to a conveyance system Area B in Figure 11 1 123 December 2009 Figure 11 1 Simplified Impervious Area Connectivity Depiction The PLRM simulates runoff and pollutant loading individually for specific land uses e g Single Family Residential within a catchment Therefore the user must estimate the percentage of DCIA for the specific land uses contained within a catchment even t
122. iption This table includes daily evaporation rates in inches per day organized as monthly normals Evaporation rates are used to calculate evaporation and transpiration over the simulation period Structure Evaporation rates are input as monthly normals in units of inches day Reference See Section 4 4 of the Model Development Document Groundwater Description Values for parameters in this table are used to compute rate of groundwater flow which affects computations that determine the volume of infiltrated runoff that percolates to groundwater relative to the amount that is transpired Structure The table includes one row and a number of columns formatted in a manner to inform the SWMMS code A description of each field can be reviewed by opening the table in Design View in Access Reference See Section 4 2 of the Model Development Document HydSoilGroup Description This table relates hydrologic soil group to soil suction head Structure The table is used with the Soils table to provide a value for soil suction head for the Green Ampt equation in the SWMM5 code used to compute infiltration Hydrologic soil group is defined based on user entry in the Soils Editor The following are functions of key columns in the table e HSC hydrologic soil group e SoilSuctionHead the assigned soil suction head for the associated hydrologic soil group Reference See Section 4 1 of the Model Development Document PLRM User s Manua
123. is automatically done based on the information entered in the Land Use Conditions Editor for BMP Implementation In PLRM User s Manual 26 December 2009 our example we entered in the Land Use Conditions Editor that 25 of the Single Family Residential area had BMP Retrofit Certificates Based on the definition of the BMP Retrofit Certificates this means that 25 of the area for that land use 1s draining to infiltration facilities For this example we ll assume that the impervious area associated with Remaining Area Draining to Outlet in Single Family Residential is roughly 50 directly connected to the outlet DCIA 50 Note that these assumptions are the default values for the PLRM so there are no changes to make on the Parcel Methodology portion of the Drainage Conditions Editor Click the OK button to close the form and return to the Catchment Properties Editor At this point all information required for the catchment has been completed On the Catchment Properties Editor click the OK button to close the form and return to the Schematic Window 2 6 Storm Water Treatment There are a number of Storm Water Treatment SWT facilities than can be simulated in the PLRM For this Quick Start Guide we ll go over how to input information for a Dry Basin Section 8 describes inputs parameters for all SWT facilities in the PLRM To enter and edit SWT data for a Dry Basin double click on the Dry Basin icon we created from the Schematic
124. ject where storm water runoff from the catchment will drain The field Flows to contains a drop down box to select the object that receives flow from the catchment Objects that can receive flow include junctions outfalls dividers or other SWTs Only previously created objects will be available to select from the drop down box For this example select DryBasin1 which is the dry basin previously created PLRM User s Manual 17 December 2009 Step 1 Define Physical Attributes Within the context of the PLRM the key physical attributes of a catchment are the catchment area defined in acres and the average slope of the catchment defined as a percent slope For this example set the catchment area equal to 10 acres and the slope equal to 5 percent After entering the information click on the button Step 2 Define Land Uses Step 2 Define Land Uses The Land Use Editor is shown in Figure 2 9 The form is pre populated with Tahoe Basin land uses as defined by the Lake Tahoe TMDL The TMDL Land Use GIS Layer can be downloaded from the Lahontan RWOCB website http www waterboards ca gov lahontan water_issues programs tmdl lake_tahoe index shtml The pre populated land uses are selectable from the box titled Available Land Uses To adda land use to the catchment click on the name of the desired land use within the selection box Available Land Uses With the desired land use highlighted click on the Single Arrow button This will
125. l 139 December 2009 LandUseParcels Description This table includes SWMMS3 code required for each land use and associated pollutant of concern to simulate street sweeping intervals Because the PLRM uses external algorithms to estimate the effectiveness of street sweeping all values in this table are zero Structure The table includes each unique land use in the PLRM A description of each field can be reviewed by opening the table in Design View in Access Reference None cited The SWMMS algorithms for sweeping are not used in the PLRM but the code is transferred from the PLRM Database to the SWMM5 input file to ensure the SWMMS simulation executes correctly LandUses Description This table includes TMDL land uses that will be selectable from Land Use Editor The table includes default values for the percentage of impervious area associated with each land use that appear in the Impervious field of the Land Use Editor Structure Available land uses in the Land Use Editor are populated from this table The following are functions of key columns in the table e code value in the Codes table of the PLRM Database e name name of land use e PLRM_Name abbreviation used in XML code to generate a SWMM5 input file e defaultlmpervFraction default values that populate the Impervious field of the Land Use Editor e description describes family of codes land uses can be any code from 100 199 Reference Default land uses incl
126. l Runtime on a user s computer to ensure the interacts with the PLRM PLRM successfully interacts with the PLRM Database Database regardless of the presence of Microsoft Access 2007 Figure 11 1 illustrates the function of the PLRM Database within the overall PLRM program structure The PLRM Input Forms interact with the PLRM Database to automate many of the data entry needs required for a simulation Besides the storage of Default Parameters the PLRM Database executes technical algorithms on certain data sets to generate required data entry based on user entry in the PLRM Input Forms For example location specific meteorological data sets are created from the PLRM Database based on the meteorological grid cell the user defines in the Project Editor PLRM User s Manual 135 December 2009 Typical User Interacts Solely with Input and Output Forms PLRM Input PLRM Output Forms Forms PLRM Input PLRM Database File XML Input Output Processor Processor SWMM5 Binary Output File Figure 11 1 PLRM Database and Program Structure The remainder of this section provides an overview of the content included in each table in the PLRM Database The name of each PLRM Database table is provided in bold below For each table the overview 1s organized as follows 1 Description provides a brief summary of the content and purpose of the table 2 Structure describes the format of the table key fields and when applic
127. lbs yr TN lbs yr DIN lbs yr Figure 2 18 Scenario Report Creating and Viewing Scenario Comparisons Estimates of pollutant load reductions are created in the PLRM through Scenario comparisons So far in our example we have only created one Scenario so we cannot view a Scenario comparison To quickly create another Scenario from the Schematic Window return to the Project and Scenario Manager by clicking on the Project Manager button in the Function Toolbar Figure 2 6 PLRM User s Manual 31 December 2009 In the Project and Scenario Manager expand the tree structure for our Project by clicking once on the plus sign next to the name of our Project Then click on the name of the Scenario we created to highlight the Scenario Finally with the Scenario highlighted click on the button Copy Selected This will copy our Scenario into the Project and open the Scenario Editor In the Scenario Editor for the field Scenario Name rename the Scenario to Scenario2 and click the Next button The Schematic Window will now be shown with the copied Scenario Key Concept Box The results shown in the PLRM Scenario Report are pollutant loads Pollutant load reductions are calculated by comparing multiple Scenarios within the same Project using the Scenario Comparison Report Now we ll slightly modify Scenario to illustrate how pollutant loads are compared by the PLRM Double click on the Dry Basin icon to bring up
128. ld be a dry well an infiltration trench or any other physical structure designed to store and infiltrate runoff An Infiltration Facility is different from an Infiltration Basin in that Infiltration Facilities are smaller features distributed throughout a catchment that store and infiltrate distributed storm water runoff whereas an Infiltration Basin stores and infiltrates concentrated storm water runoff Input Parameter parameters that are accessible from the PLRM Interface The structure of the PLRM was developed to streamline input data entry by limiting the number of parameters accessible from the PLRM Interface to those that are project area specific and are sensitive in terms of influencing PLRM output Hydrologic Source Control HSC Facility an Infiltration Facility or a Pervious Dispersion Area Hydrologic Source Controls HSCs reduce runoff volumes and minimize the concentration of storm water runoff through distributed runoff interception infiltration and disconnection of impervious surfaces HSCs primarily function to increase infiltration which routes precipitation or surface runoff to groundwater Parcel Methodology defines the condition of predominantly private land uses Single Family Residential Multi Family Residential CICU and Vegetated Turf to estimate pollutant loads generated The Parcel Methodology allows for separate definition of private property BMP implementation for each applicable land use withi
129. le Figure 6 4 Road Shoulder Condition Decision Process PLRM User s Manual 58 December 2009 Mark up the hard copy map with the dominant road shoulder condition by block or your preferred spatial resolution using a color coded legend Distinguish between left and right road shoulder conditions if they are markedly different on the same block Step 4 For each Road Risk category in the catchment estimate the percentage of area that equates to a particular road shoulder condition The percentage of area can be estimated by transferring the hard copy map information to GIS or AutoCAD and tabulating distances by Road Risk Category Transferring the information to digital form will also allow for better presentation and subsequent use in alternatives evaluation The estimate of road shoulder condition does not need to be precise The intent of the Road Methodology 1s to reasonably estimate the general distribution of road shoulder conditions e g Are the road shoulders 0 25 50 75 or 100 stable Users may deviate from these recommended steps based on available resources and compatibility with other planning and maintenance activities the key objectives are 1 categorization of road segments at a reasonable resolution and 2 production of a digital record for use in model input and analysis Definitions of Road Shoulder Condition 1 Stable The road shoulders have physical improvements or other elements that either 1
130. lity assure and modify as needed the designations of Road Risk in the default Road Risk GIS Layer provided with the PLRM Step 2 Print out a hard copy map of each catchment with the Road Risk Categories distinguishable on the map 1 e High Moderate and Low Risk roads distinguished Step 3 Use either field survey Google Maps Street View or a combination to develop an inventory of road shoulder conditions for a catchment Figure 6 4 provides a decision process for determining road shoulder condition Detailed definitions of each road shoulder condition are provided after Figure 6 4 The decision process of Figure 6 4 is used to estimate condition of the road shoulder for pollutant generation and does consider the connectivity of the road shoulder to the drainage system Connectivity is an important factor in estimating pollutant loads and Section 7 of this Manual Define Drainage Conditions describes the appropriate place and methods in the PLRM to incorporate impervious area connectivity Question 1 Could storm water Question 2 Can automobiles and or runoff collect along the snow plow activity disturb a significant Erodible road shoulder and cause erosion portion of the unpaved road shoulder Question 2 Can automobiles and or O A snow plow activity disturb a significant portion of the unpaved road shoulder Protected __ Decision Point Road Shoulder Condition a a a a a a a a md Stable and Protected Stab
131. lly with this table to continuously update Sweeping Effectiveness based on user entry which in turn adjusts CRCs in the Road Conditions Editor A description of each field can be reviewed by opening the table in Design View in Access e SweeperTypeScore value in the column relates to the Codes table for the specific sweeper type e SweepFrequencyScore value in the column relates to the Codes table for the specific sweeping strategy e PollutantCode Pollutant code from the Codes table e Percent_Red Percent reduction in CRC based on the combination of sweeper type and sweeping strategy selected in the Road Conditions Editor for each pollutant of concern PLRM User s Manual 145 December 2009 Reference Section 5 1 and Appendix B of the Model Development Document describe how default street sweeping effectiveness values were developed SWTCECs Description The table includes default characteristic effluent concentrations CECs for each SWT facility and pollutant of concern in the PLRM Default values are use to populate CECs in the SWT Editors e g Dry Basin Editor Wet Basin Editor Structure A description of each field can be reviewed by opening the table in Design View in Access notable columns in the table include e SWT_Code value relates to the Codes table to define the specific SWT facility e CEC Value default CECs for each SWT facility and each pollutant of concern Reference See Section 7 2 of the Model Deve
132. long term simulation 18 years without significant maintenance The recommended range was developed based on analysis of literature values that relate Hydrologic Soil Group HSG to Ksat NRCS 2007 While it 1s recognized that HSG does not directly correlate to the long term performance of an Infiltration Basin the relationship was used to conservatively bound expected performance Sensitivity tests show that values above the recommended range strongly influence results and may result in overly optimistic estimates of long term load reductions The PLRM provides a suggested default value of 0 4 inches hour for infiltration rates as an estimate of the characteristic long term performance of infiltration in an Infiltration Basin When modifying the suggested default value the user should ensure that a characteristic value is provided and not an optimal value A characteristic value is defined as the average expected condition of the Infiltration Basin over the life span of the Infiltration Basin while factoring in assumptions for anticipated or committed maintenance 7 NRCS U S Department of Agriculture 2007 National Engineering Handbook Part 630 Hydrology Chapter 7 Hydrologic Soil Groups PLRM User s Manual 130 December 2009 Brim Full Draw Down Time Flagged As Range Message Reference Guidance PLRM User s Manual Warning Low 48 hours High 72 hours The brim full draw down time 1s the number of
133. lopment Document SWTDesignParameters Description The table includes default design parameters organized by SWT facility Default values are used in the SWT Editors e g Dry Basin Editor Wet Basin Editor Structure A description of each field can be reviewed by opening the table in Design View in Access notable columns in the table include e SWT_Code value in the column relates to the Codes table to define the specific SWT facility e variable description of design parameter e defaultValue default value used by in the SWT Editors Reference See Section 7 1 of the Model Development Document TempTimeSeries Description This table includes an 18 year data set Water Year 1989 to 2006 of temperature for eight SnoTel gages in the Tahoe Basin Data is provided in degrees Fahrenheit at hourly intervals Structure The columns in the table are formatted so the time series can be read exported and read directly as a SWMM5 input file for temperature The column SnoTellD is the code identifying the SnoTel station The column AirTemp is the temperature recorded at that SnoTel station for the specific hour in degrees Fahrenheit Reference See Section 3 of the Model Development Document PLRM User s Manual 146 December 2009 12 0 Notes on PLRM Modeling 12 1 Limitations and Structure of Version 1 Catchment simulation size The PLRM was built for the typical Tahoe Basin storm water quality improvement project scale i e ro
134. modifications or additions The database structure was developed to dynamically interact with the PLRM Interface so that future updates or modifications to PLRM Database are reflected in the PLRM without the need to redesign and recompile the program Note that as discussed in the previous section the Default Parameters included within the PLRM Database are not recommended for modification by the user unless the modifications are done to incorporate new or additional data Maintaining consistent Default Parameters in the PLRM Database 1s recommended because it will help to maintain consistency of results generated by multiple user s across multiple project areas During the installation process for the PLRM the PLRM ey Concept Box Database is unpacked and saved into the Data Directory with a filename of PLRMv1 0 accdb The PLRM Database was built in Microsoft Access 2007 and a user A user needs to have Microsoft Access 2007 installed on their computer to view the PLRM needs to have Microsoft Access 2007 installed on their Database However Microsoft computer to view the PLRM Database However Access 2007 does not need to be Microsoft Access 2007 does not need to be installed on installed to run the PLRM The a user s computer to run the PLRM The PLRM setup PLRM setup program includes program includes cae free software Microsoft Access Hok saa dd noth ce Rune 2007 CULT The PLRM setup program to ensure the PLRM successfully will instal
135. more sensitive input parameter and the modeler should be mindful of performance results produced by the PLRM for flow based SWT facilities at the outlets of small catchments 2 Large catchments the PLRM was not developed with the intention of simulating pollutant loading from large catchments e g TMDL subwatersheds or TRPA watersheds The following are limitations of the PLRM for simulating large catchments that the user should consider a The PLRM uses simplified routines for hydrologic routing of storm water that may not adequately represent runoff characteristics in large catchments b The PLRM allows only one meteorological file to be assigned to a Project Given strong orographic effects in the Tahoe Basin a single large catchment can have markedly different precipitation and temperature characteristics and these characteristics won t be represented Pervious Dispersion Areas A Pervious Dispersion Area is an urban lot or collection of urban lots where storm water is dispersed and infiltrated to simulate the implementation of a Hydrologic Source Control HSC A Pervious Dispersion Area can be added to a simulation using the Pervious Dispersion Area Editor which is accessed from the Drainage Conditions Editor In PLRM Version 1 defining a Pervious Dispersion Area will add area to the simulation above that specified by the user in the Land Use Editor Depending on the size of the Pervious Dispersion Area this could cause a
136. n length of catchment Editor j The percentage of impervious area Percent DCIA draining directly to conveyance systems Key parameter in the Green Ampt equation Used to calculate infiltration for pervious areas Ksat for Pervious h Drainage Area MOU Volume of surface Drainage Enno Conditions Editor Storage of precipitation provided through ponding surface wetting and interception on pervious surfaces Pervious Depression Storage n Storage of precipitation provided through ponding surface wetting and interception on impervious surfaces Impervious Depression Storage n Infiltration Key parameter in the Green Ampt Facility or equation Used to calculate Pervious infiltration for a HSC Dispersion Area Editor Volume of surface in hour runoff infiltrated by the HSC Ksat for an HSC Facility PLRM User s Manual 119 December 2009 Influence on PLRM Output Inout P t Descrinti Location in Recommended Range A AAE dd PLRM Interface Storage provided by an HSC calculated as a depth of precipitation Volumetric capture efficiency of the HSC which affects the volume of surface runoff infiltrated by the HSC Unit Area Storage for an Infiltration Facility Infiltration over the impervious area routed to p Facility Editor the specific HSC i e 1 inch is the default 20 year 1 hour storm Volume of surface in hour runoff infiltrated by the Dry Basin C iow mig
137. n Infiltration Basins are constructed with a highly permeable base to promote infiltration To access the Infiltration Basin Editor add an Infiltration Basin to the Schematic Window and double click on the Infiltration Basin icon This will bring up the LJ Infiltration Basin Editor as shown in Figure 8 4 En Infiltration Basin Editor a a e Infiltration Basins Edit Object Name InfiltrationBasin1 Flows To Outfalll Design Parameters Custom Wolume Discharge Curve Parameters Default Value User Value Water Quality Yolume 2500 2500 Footprint 1000 1000 Infiltration Rate 0 4 0 4 OLE here 10 see hematit With parameter gegra tiors Lake Tahoe PLRAM v1 0 Figure 8 4 Infiltration Basin Editor PLRM User s Manual 90 December 2009 The following are data entry fields for an Infiltration Basin e Name edit the default name of the Infiltration Basin if desired By default the PLRM will name Infiltration Basins in a Scenario sequentially as InfiltrationBasin1 InfiltrationBasin etc e Flows to contains a drop down box to select the object that receives flow from the Infiltration Basin Objects that can receive flow include junctions outfalls dividers or another SWT Only previously created objects in the Schematic Window will be available to select from the drop down box Design Parameters The Infiltration Basin Editor requires entry of key Design Parameters to simulate the performance of the In
138. n a catchment Pervious Dispersion Area an urban lot or collection of urban lots where storm water is dispersed and infiltrated PLRM User s Manual 152 December 2009 Pollutant Source Controls PSCs reduce the generation of pollutants of concern at their sources by inhibiting or reducing mobilization and transport of pollutants with storm water Project a set of analyses within the PLRM used to compare existing or proposed storm water conditions to predict potential pollutant load reductions Note that a Project is also a defined physical area that cannot vary among Scenarios which ensures results are comparable Road Land Uses Primary Roads and Secondary Roads Primary Roads include all state and U S roads as well as major arterial roads in the Tahoe Basin Secondary Roads are all urban roads in the Tahoe Basin that are not Primary Roads Road Land Uses are a subset of Urban Land Uses Road Methodology defines the condition of public right of ways which is used to estimate pollutant loads generated from Road Land Uses The Road Methodology allows for separate definition of the condition of Primary Roads and Secondary Roads within a catchment The methodology applies to primary and secondary roads as a land use and thus includes paved and unpaved areas within the right of way and not just the road pavement areas Road Risk used to categorize the pollutant potential of a road segment based on physiographic charac
139. n in Figure 8 19 Ee Flow Divider Editor Flow Dividers Name Dividerl Cutoff Flow Rate cfs 1 E a Flows Above Cutoff Go To Outfall2 Flows Below Cutoff Go To Outfall3 Y Figure 8 19 Flow Divider Editor The following are data entry fields for a Flow Divider e Name edit the default name of the Flow Divider if desired By default the PLRM will name Flow Dividers in a Scenario sequentially as Dividerl Divider etc e Cutoff Flow Rate cfs the threshold flow rate controlling the bifurcation of storm flows e Flows Above Cutoff Go To contains a drop down box to select the object where high flows should be routed Only previously created objects in the Schematic Window will be available to select from the drop down box e Flows Below Cutoff Go To contains a drop down box to select the object where low flows should be routed Only previously created objects in the Schematic Window will be available to select from the drop down box PLRM User s Manual 108 December 2009 9 0 Running the Model and Viewing Results After all information 1s entered for a Scenario a simulation can be initiated by Run 2 clicking on the Run button on the Schematic Window within the Function Toolbar As the PLRM begins to run in the background your default web browser will open and display the Recommended Range Report Figure 9 1 The Recommended Range Report flags user entered input that is
140. n the PLRM Model impervious area connectivity Development Document Section 5 1 Appendix B and Appendix C This section of the User s Manual describes how to apply the Road Methodology in the PLRM as it pertains to Pollutant Generation and PSC Implementation The definitions and methods in this section are focused on defining CRCs rather than loads and are not influenced by the connectivity of impervious area to downstream receiving waters Connectivity is an important factor in estimating pollutant loads and Section 7 of this Manual Define Drainage Conditions describes the appropriate place and methods in the PLRM to incorporate impervious area connectivity PLRM User s Manual 51 December 2009 6 1 1 Road Risk Categories As shown in the Land Use Conditions Editor Figure 6 1 the first step in the Road Methodology is to define the distribution of Road Risk for Primary Roads and Secondary Roads Road Risk is used to categorize the pollutant potential of a road segment based on physiographic characteristics that are assumed to most strongly influence the quality of storm water generated specifically Slope Traffic Density and Adjacent Land Use The rationale for selecting these physiographic characteristics to define Road Risk is summarized as follows e Slope Steeper sloped roads generally receive more frequent road abrasive applications Additionally storm water on steeper sloped roads is conveyed at higher velocities which
141. narios will be associated with a single Project because the comparison of Scenarios produces the estimates of pollutant load reductions To create a new Project select the New Project button on the Project and Scenario Manager This will bring up the Project Editor as shown in Figure 2 3 A default project name is provided by the PLRM and can be changed in the field Project Name Additional supplemental information about the Project can be entered on this form that will be included in the summary results PLRM User s Manual 10 December 2009 BR Project Editor Project Information Project Mame EIP Number if applicable Po Implementing Agency Po Project Location Description Po Project Location Grid No y Continous Simulation Length Short Simulation O Full Simulation Sawe Project Info Lake Tahoe PLAM v1 0 Figure 2 3 Project Editor The only information that must be entered in the Project Editor for the program to continue 1s the Project Location Grid Number If you click on the button Find Met Grid this will activate an image of the Tahoe Basin overlain with a grid You can zoom and browse through the image to find your Project area and enter the associated grid number For now enter 204 which is the grid number for Tahoe City Then click on the button Save Project Info This will close the Project Editor and return you to the Project and Scenario Manager The Project and Scenario Manager organizes Proje
142. narios will be compared against The Baseline Scenario is typically the existing conditions Scenario but it doesn t need to be Once selected the runoff volume and pollutant loads of the Baseline Scenario are summarized at the top of the two grid boxes at bottom of the form 3 Inthe selection box titled Available Scenarios and Results select a Scenario to compare to the Baseline Scenario and click on the right arrow The runoff volume and pollutant loads of the selected Scenario will be added to the first grid box and the pollutant load reduction between the Baseline Scenario and the selected Scenario will be summarized in the second grid box Multiple Scenarios within a Project may be compared simultaneously using the approach outlined in this step 4 Pollutant load reductions and or comparisons of the effectiveness among various storm water improvement alternatives may be viewed as absolute or relative values by clicking on the tabs at the top of the second grid box 5 The Scenario Comparison Report may be exported to a comma delimited text file by clicking the Export button The Scenario Comparison Report compares and estimates differences in total pollutant loading among Key Concept Box Scenarios using the Scenario Total output at the bottom of the Scenario Report If the user wishes to explore more The Scenario Comparison detailed results among Scenarios such as differences in Report compares and estimates differences in total
143. nce The user may have performance estimates for a specific type of media or from a manufacturer that suggest using a different higher filtration rate However when modifying the suggested default value the user should ensure that a characteristic value is provided and not an optimal value A characteristic value is defined as the average expected condition of the SWT over the life span of the SWT while factoring in assumptions for anticipated or committed maintenance PLRM User s Manual 133 December 2009 Characteristic Effluent Concentration Flagged As Range Message Reference Guidance PLRM User s Manual Warning Defaults depend on the type of SWT and pollutant of concern Characteristic Effluent Concentrations CECs were developed through a statistical analysis of storm water performance data to predict a representative level of treatment for each type of SWT facility included in the PLRM Modification to CECs values should be justified by the user and the program will flag any value for any pollutant of concern that deviates from the default value The development of the existing default CEC values for each type of SWT facility included in the PLRM are described in the PLRM Model Development Document Section 7 2 The PLRM provides suggested default CEC values As noted in Section 7 2 of the Model Development Documentation additional work is needed and is underway to improve the default CEC values The cu
144. ncludes Primary Road mostly highways and Secondary Road land uses The Road Methodology allows for separate definitions of the condition of Primary Roads and Secondary Roads within a catchment e The Parcel Methodology defines the condition of predominantly private land uses Single Family Residential Multi Family Residential CICU and Vegetated Turf The Parcel Methodology allows for separate definitions of private property BMP implementation for each applicable land use within a catchment The discussion below provides a quick example for entering the required information for the two methodologies Section 6 of this User s Manual provides detailed information and guidance on the definition of input variables and the use of the two methodologies in estimating pollutant loads from actual catchments Road Methodology The first step in the Road Methodology defines Road Risk using three categories High Moderate and Low The three categories of Road Risk are related to the anticipated quality of storm water runoff generated from a road based on key physiographic and anthropogenic characteristics Within each risk category Road Conditions are used to further define expected pollutant concentrations For this example enter the Road Risk distribution for Secondary Roads as shown in Figure 2 11 High 30 Moderate 30 and Low 40 Note that the value in the High column is calculated based on the values enter
145. nd Scenario at the Outfall s defined for that Scenario If l summarizes average annual storm water runoff is not routed to an Outfall then the runoff volumes and pollutant Scenario Report Section 9 1 of this Manual will not loading of a Scenario at the report all runoff and pollutant loading for the Scenario Outfall s defined for that Scenario PLRM User s Manual 106 December 2009 Junction Editor To access the Junction Editor add a Junction to the Schematic Window and double click on the Junction icon This will bring up the Junction Editor as shown in Figure 8 18 ES Junction Editor EROS Name Junction4 Flows to Node Ml Figure 8 18 Junction Editor The following are data entry fields for a Junction e Name edit the default name of the Junction if desired By default the PLRM will name Junctions in a Scenario sequentially as Junction1 Junction2 etc e Flows to contains a drop down box to select the object that receives flow from the Junction Objects that can receive flow include junctions outfalls dividers or an SWT Only previously created objects in the Schematic Window will be available to select from the drop down box PLRM User s Manual 107 December 2009 Flow Divider Editor To access the Flow Divider Editor add a Flow Divider to the Schematic Window and double click on the Flow Divider icon This will bring up the Flow Divider Editor as A show
146. nd temperature minutes depending on the speed data will take up to five minutes depending on the of your computer The data is speed of your computer Click the OK button on saved and the operation will not be repeated when the same the message and in about five minutes the PLRM i i meteorological grid cell is used will complete the meteorological algorithm and the Schematic Window will become active The PLRM will save the time series of precipitation and temperature for the meteorological grid cell to your computer With the time series saved the operation will not be repeated the next time you click the NEXT button from the Scenario Editor The operation will be repeated 1f you change the meteorological grid cell in the Project Editor 3 3 Managing Projects and Scenarios on Your Computer This section describes how to manage Projects and Scenarios outside of the Project and Scenario Manager To conserve programming resources for PLRM Version 1 some file management functions e g delete a Project or Scenario are not yet incorporated into the Project and Scenario Manager but can be completed manually using Windows Explorer When the PLRM is installed on your computer a directory named PLRM 5 PLRM is created in a user specified location Within the PLRM directory three S Data directories are created Data Engine and Projects The Projects Directory is E Engine 5 Projects used to store files related to a spe
147. nd treated removed by the SWT Depending on the type of SWT there are several input parameters that influence the hydraulic capture of an SWT for example storage volume drain time water quality flow rate stage discharge relationships and infiltration rate The PLRM standardizes the representation of SWT facilities and the required user supplied input parameters for each SWT that most strongly influence hydraulic capture Water quality improvement attributed to the treatment of storm water in an SWT is modeled by applying CECs to the volume of runoff captured that exits the treatment outlet of a SWT Gf present If an influent concentration is less than a CEC for a pollutant of concern then the CEC will not be applied and effluent concentration equals influent concentration Default values for CECs are pre loaded in the database for each SWT type The current default CEC values are based on best available data and were derived from statistical analysis of multiple storm water PLRM User s Manual 84 December 2009 performance studies to predict a representative level of treatment for each SWT facility for the pollutants of concern The PLRM Model Development Document Section 7 provides additional detail on how the default CECs were developed for each SWT facility As discussed in various places in this Manual Input E Key Concept Box Parameters should be characteristic of the long term average expected condition of the SWT The PLRM
148. ndition Defaults The Road Conditions Editor is structured for data entry by Road Risk Category This allows for varying water quality strategies to be explored by Road Risk Category The Road Conditions Editor is divided into three sections where Pollutant Potential and Sweeping Effectiveness define CRCs by Road Risk Category A hyperlink to guidance for each section is provided below e Pollutant Potential e Sweeping Effectiveness e Characteristic Runoff Concentrations CRCs EN Road Conditions Editor Pollutant Potential Road Shoulder Conditions Percent Pollutant i Road Abrasive Erodible Protected Stable Stable and Potential Road Risk Application Strategy Protected Score High Minimal control measures Moderate Moderate Control Measures Low 4dyanced Control Measures Sweeping Effectiveness i Sweeping Effectiveness Road Risk Type of Sweeper Sweeping Frequency Score High Mechanical Broom Winter 0 times Summer 1 2 times wt 1 0 Moderate Mechanical Yacuum Sweeper Tandem Operatic Winker twice monthly Summer 1 2 times ka a Shou Late High Efficiency Yacuurm Assisted Dry Sweeper w Winter after abrasive application Summer monthly w Characteristic Runoff Concentrations Pollutant Delivery Factors Pollutants of Concern mg L Fi Ines Road Risk T55 FSP TP SRP TN Dissolved Particulates High Moderate Lor Lake Tahoe PLAM v1 0 Figure 6 3 Road Conditions Editor PLRM User s Manual 5
149. nflow o Draw Down Time Wet Pool Volume Minimum HAT r Inflow Figure 8 8 Wet Basin Representation in PLRM As shown in Figure 8 8 two parallel storage units are used to simulate treatment within the Wet Pool and Surcharge Storage Inflow equal to or below the computed maximum wet pool treatment flow rate Qmax 1n Figure 8 8 is routed to the Wet Pool Inflow in excess of Qmax 18 routed to the Surcharge Storage where treatment will occur for flow that exits through the treatment outlet of the Surcharge Storage The Treatment Rate of the Surcharge Storage is defined as a function of the Surcharge Basin Volume and the Brim Full Draw Down Time Storm water that passes through the bypass outlet when the Surcharge Basin Volume is exceeded is considered Bypass Flow The quality of Bypass Flow is equal to the influent concentration of the storm water entering the Wet Basin Infiltration is not simulated for a Wet Basin The quality of Treated Flow from the Wet Pool is assigned CECs for pollutants of concern as defined in the Wet Basin Editor The Wet Basin Editor allows for modification of CEC values but any modification should be justified by the user The CECs for the Surcharge Storage are fixed values that relate the Wet Basin CECs to multipliers contained in the PLRM Database For the default values in the PLRM Database the ratios are set as the difference in CECs between a Wet Basin and a Dry Basin The multiplier approach ensure
150. ng Low 1 0 High 1 0 The Pollutant Delivery Factors provide a method to adjust the quantity of pollutants of concern delivered to the outlet of the catchment This option was incorporated recognizing that the Road Methodology does not account for every PSC action that may be implemented to improve runoff quality Values other than are acceptable as Pollutant Delivery Factors but are flagged because the user should provide justification to project reviewers when Pollutant Delivery Factors other than 1 are used The Pollutant Delivery Factors adjust the CRCs for pollutants of concern No specific reference is cited Pollutant Delivery Factors are an internal algorithm implemented in the PLRM to provide a flexible and transparent process for adjusting CRCs if the Road Methodology is not deemed to be sufficient to represent PSCs for roads Developing the rationale and justification for using a Pollutant Delivery Factor other than 1 is the responsibility of the user 121 December 2009 Average Slope Flagged As Range Message Reference Guidance PLRM User s Manual Warning Low 1 High 30 The average slope is bounded by a recommended range to ensure the user has entered a reasonable value Values outside the recommended range will be rare for Tahoe Basin urban areas and the user should double check their calculation of average slope The recommended range was developed based on review of calculations of slopes
151. ng with this Quick Start Guide add a single Catchment Dry Basin and Outfall to the Schematic Window To add each of these objects Click once on the desired object within the Object Toolbar The cursor will change to an icon that resembles cross hairs Move the cursor into the white space on the Schematic Window and click once The object you selected form the Object Toolbar should appear Select the next object you would like to add from the Object Toolbar and repeat the process After adding each object your example should appear similar to Figure 2 7 When all objects have been created click on the Selection Tool Arrow Icon within the View Toolbar to close the session for adding objects and to allow access to Input Forms for the objects created Note that storm water routing between objects is not defined from the Schematic Window but from within the individual Input Forms PLRM User s Manual 15 December 2009 Ea Lake Tahoe PLRM v1 0 Project Name Projecti Scenario Name Scenario1 Project Manager iai Save i Aun EA Compare Scenarios l View Report Export Report E k aa H El Catch LJ B A LJ m 4 Cutral fa E Figure 2 7 Quick Start Example Elements 2 3 Entering Catchment Data To enter and edit catchment data double click on the Catchment icon from the Schematic Window This will bring up the Catchment Properties Editor as shown in Figure 2 8 The Catchment Properties Edito
152. o Estimate of characteristic infiltration ito BAG Volume of surface rate for a storm water treatment l 0 05 1 5 in hour runoff infiltrated by the Infiltration Basin sie Editor facility Infiltration Basin DES ES Estimate of characteristic infiltration rate for a storm water treatment Dry Basin Editor facility Infiltration in a Dry Basin Drain time for the water quality Dry Basin Editor Brim Full Draw volume of a basin i e amount of Infiltration Basin Down Time time it takes to drain from brim full Editor and Wet to empty Basin Editor hours Volumetric capture efficiency of the SWT which affects the hours volume of surface runoff treated by the SWT Minimum hydraulic residence time of the permanent pool of a Wet Basin HRT of Wet Pool used to compute the maximum flow Wet Basin Editor through rate for which treatment is effective Characteristic treatment flow rate l l Filtration Rate Bed Filter Editor through the filter media Characteristic Characteristic effluent in hour Defaults in Database b SIAMA to Ay Pollutant loads reduced by SWT facilities SWT Editors e g SWT see Database table SWTCECs Effluent concentrations for SWT facilities for Dry Basin Editor Concentrations treated surface runoff y SL 2 PLRM User s Manual 120 December 2009 Pollutant Delivery Factors Flagged As Range Message Reference Guidance PLRM User s Manual Warni
153. o be over predicted because the CEC values for SWTs are not explicitly linked to design information the user enters in the PLRM A HRT less than the recommended minimum will increase the capture efficiency of the Wet Basin but will not consider how decreased HRT may decrease treatment performance for surface runoff exiting the Wet Basin As an example if the anticipated baseflow for the Wet Basin is 0 1 cfs then with a minimum HRT of 24 hours the Wet Pool Volume would need to be at least 8 640 cf Where Wet Pool Volume HRT Baseflow Wet Pool Volume 24 Hours 0 1 cfs 3600 seconds hour Wet Pool Volume 8 640 cf 132 December 2009 Filtration Rate Flagged As Warming Range Low 0 5 in hour High 2 5 in hour Message The filtration rate is specific to a Bed Filter e g sand filter The filtration rate is the characteristic rate of surface runoff passing through the media in the bed filter A filtration rate below the minimum recommended range indicates that the bed filter is not functioning for storm water treatment A filtration rate above the maximum recommended range should be justified as a hydraulically loaded SWT may not perform above the recommended maximum over the long term simulation 18 years without significant maintenance Reference The recommended range was developed based on typical filtration rates reported for storm water in Table 10 15 of the reference Stormwater Treatment Minton 2005 Guida
154. o low for a pervious area unless it is absent of vegetation and the soil is compacted Pervious depression storage above the maximum 1s unlikely for an urban area unless the pervious area is heavily vegetated or forested with a thick duff layer SWMM User s Manual Table A 5 Values within the recommended range should be used unless supporting information that justifies deviating outside the recommended range is provided A value close to 0 1 should be used for pervious areas without significant vegetation or forest cover A value closer to 0 2 should be used for areas with thick vegetative cover or a forest litter layer Impervious Depression Storage Flagged As Range Message Reference Guidance PLRM User s Manual Warning Low 0 02 inches High 0 1 inches Depression storage 1s used to simulate the storage of precipitation provided through ponding surface wetting and interception Impervious depression storage outside the recommended range is unlikely SWMM User s Manual Table A 5 The default value is 0 05 Values within the recommended range should be used For PLRM Version 1 it is recommended that 0 05 inches 1s used 126 December 2009 Ksat for a HSC Facility Flagged As Range Message Reference Guidance Warning Low 0 05 in hour High 1 0 in hour Infiltration in Hydrologic Source Controls HSC is simulated using the Green Ampt equation and values for saturated hydraul
155. of the data typically collected for a Tahoe Basin Existing Conditions Analysis SWQIC 2004 Parameters accessible from the PLRM Interface are termed Input Parameters Parameters that are necessary fora SWMMS simulation but either do not strongly influence PLRM output e g Manning s n or are typically not project specific e g snowmelt coefficients are included in the PLRM Database see Section 11 Parameters that are not directly accessible from the PLRM Interface are termed Default Parameters Section 10 1 describes the most sensitive Default Parameters and the way that they influence PLRM output Section 10 2 describes key Input Parameters The guidance in Section 10 2 is limited to Input Parameters that are not easily measured e g percentage of directly connected impervious area or may vary over time e g infiltration rates Input Parameters that are easily measured and are relatively static values e g quantity of impervious area are assumed to be relatively straightforward for the user and are not discussed in this section although they may strongly influence PLRM output PLRM User s Manual 116 December 2009 10 1 Default Parameters Table 10 1 lists the most sensitive Default Parameters in the PLRM Database and includes a description of each parameter the specific location in the PLRM Database and a brief summary of how each default parameter influences PLRM output Documentation regarding the development of default
156. on by adjusting PLRM Database defaults If complex groundwater issues need to be evaluated for a project area then the use of the PLRM and its parent model SWMM5 are likely not the appropriate model The interested reader is directed to Section 4 2 of the Model Development Document for more information on the groundwater algorithms employed and the default values used Snowfall Snow Accumulation and Snowmelt While not discussed in this Manual the PLRM computes snowfall snow accumulation and snowmelt throughout the long term continuous simulation The parameters and algorithms used for the computations of snowfall snow accumulation and snowmelt are specific to the routines employed by SWMMS5 For consistency of application among PLRM users as well as to simplify the date entry requirements on the user snow hydrology is not accessible to the user from the PLRM Interface Snow hydrology parameters are Default Parameters accessible only through the PLRM Database The interested reader is directed to Section 4 3 of the Model Development Document which discusses Snow Hydrology and default parameters used in the PLRM Outfalls Outfalls are required objects in any PLRM simulation because the PLRM calculates and summarizes average annual runoff volumes and pollutant loading of a Scenario at the Outfalls defined for that Scenario If storm water runoff is not routed to Outfalls then the Scenario Report Section 9 1 of this Manual will not include
157. ons Note that a Project 1s also a defined physical area that cannot vary among Scenarios which ensures results are comparable Scenario a unique PLRM simulation associated with a specific Project A Scenario typically represents existing conditions or a potential water quality improvement alternative The comparison of Scenarios within a Project produces an estimate of pollutant load reduction Multiple Scenarios are associated with a single Project e g Existing Conditions Alternative 1 Alternative 2 etc EA Project and Scenario Manager Double Click on a Project Scenario to Begin a Copy Selected Scenariol New Project Project or Scenario Files at C Program Files PLRM Projects Project1 Lake Tahoe PLRM v1 0 Figure 3 1 Project and Scenario Editor PLRM User s Manual 34 December 2009 The following functions are executed by the Project and Scenario Manager New Project Creates a new Project and launches the Project Editor The PLRM will provide a default name for the Project which can be renamed within the Project Editor New Scenario Creates a new Scenario and launches the Scenario Editor The PLRM will provide a default name for the Scenario which can be renamed within the Scenario Editor Note that this function only works when a Project is selected in the Project and Scenario Manager because a Scenario must be associated with a Project Copy Selected Copies and adds the selected
158. ons from the Catchment Properties Editor This will bring up the Pollutant Source Controls Editor as shown in Figure 2 11 The Area column will be populated based on information entered in the Land Use Editor In this example the Secondary Roads and Single Family Residential land uses were defined in the Land Use Editor as shown by the values populated in the Area column Figure 2 11 Note that the current version of the form will display all available urban land uses in the PLRM but the Area for land uses that are not defined as present will be zero While the form would allow entry of information for urban land uses not present in the catchment the program would not use the input Land Use Conditions Editor Applicable Catchment Catchment ID Catchi Area 10ac Road Methodology Road Risk Categories Define Road Area of Land Use Conditions High Moderate Low Primary Roads l E Edit Road Condition Defaults Secondary Roads Edit Road Condition Defaults Parcel Methodology BMP Implementation Area of Land Use Source No Contral BMP BMPs Certificate Certificate Single Family Residential Multi Family Residential CICU vegetated Turf Other Lake Tahoe PLAM v1 0 Figure 2 11 Land Use Conditions Editor PLRM User s Manual 21 December 2009 Two separate methods are accessible from the Land Use Conditions Editor to represent PSCs e The Road Methodology defines the condition of public right of ways which i
159. or The sweeper type will likely be the same for the entire project area but the user has the option to select different types of sweepers by Road Risk Category The available sweeper types to select are listed in Table 6 4 Table 6 4 Sweeper Type Road Sweeper Type Example Sweeper Hich effici E 1gh efficiency vacuum assisted Schwarze EV dustless Regenerative air dustless Elgin Crosswind Schwarze A Series Elgin Eagle or Mobil Mechanical 1988 followed by TYMCO vacuum sweeper Mechanical broom 1988 model or Elgin Eagle Mobil Mechanical newer 1988 The user selects a sweeping frequency for each Road Risk Category from the Sweeping Tandem operation mechanical vacuum sweeper Frequency drop down box in the Road Conditions Editor The description of sweeping frequency that best fits an existing practice or future commitment should be selected The option to define sweeping frequency by Road Risk Category allows a user to evaluate various levels of effort for sweeping and the potential incremental benefits of sweeping different Road Risk Categories at different frequencies The categories of sweeping frequency to select from the drop down box are as follows 1 Rare Winter 0 times summer 1 2 times 2 annual sweepings 2 Occasional Winter and summer 1 2 times per season 4 annual sweepings 3 Often Winter monthly summer 1 2 times assume roads well swept prior to first fall rain 8 annual swe
160. orm will display all available urban land uses in the PLRM but the Area for land uses that are not defined as present in the Land Use Editor will be equal to zero While the form would allow entry of information for urban land uses not present in the catchment the program would not use the input Pollutant Source Controls Editor applicable Catchment Catchment ID Catch Area 10ac Road Methodology Primary Roads Secondary Roads Parcel Methodology Single Family Residential Multi Family Residential CICL Vegetated Turf Other Lake Tahoe PLAM v1 0 Area Io oF Total Acres o Ie 20 20 Area Hy oF Total Acres Road Risk Categories Define Road 2 Area of Land Use Conditions High Moderate Low Edit Road Condition Defaults Edit Road Condition Defaults BMP Implementation Area of Land Use Source No Control BMP BMPs Certificate Certificate Figure 6 1 Land Use Conditions Editor Road Methodology PLRM User s Manual 50 December 2009 Two separate methods are accessible from the Land Use Conditions Editor to represent PSCs e The Road Methodology defines the condition of public right of ways which includes Primary Roads and Secondary Roads Primary Roads include all state and federal highways as well as major arterial roads in the Tahoe Basin e g Pioneer Trail Secondary Roads are all urban roads in the Tahoe Basin that are not Primary Roads The Road Methodology allows for
161. ormance of simulated SWT facilities and Scenario Summary results that summarize the average annual hydrology and outfall loadings ES Lake Tahoe PLRM v1 0 Project Name QuickStartGuide Scenario Name Scenario1 Status Report Project Manager 43 Save lA Run A Compare Scenarios li View Report P xport Report J About a h rze a Dale E Status Report Bookmarks D Global Information Catchments la Storm Water Treat Scenario Summary Number of years in simulation Met Grid simulated 204 Working Directory C Program Files PLRM Projects Project11 5 12 04 2009 10 06 08 12 04 2009 10 17 35 TSS lbs yr ESP 1bs yr TP 1bs yr SRP lbs yr TN lbs yr DIN 1bs yr 1451 03 TSS lbs yr Total Influent Bypass Stream 1 80 Treated Stream 2 75 Total Effluent 4 56 Volume Load Removed 0 00 1449 77 500 32 187 19 687 47 762 31 243 27 185 93 429 17 306 93 2 39 1 20 3 59 0 59 0 37 0 96 9 93 8 24 18 16 1 00 0 90 1 90 2 58 0 43 8 12 0 38 Change Removed Influent 0 04 52 58 41 80 30 68 30 89 31 59 Capture 1 Bypass Influent 60 47 41 70 acre feet yr Total Precipitation Evaporation Loss e 6 27 System Surface Discharge 4 56 Percolation to Groundwater 17 48 Continuity Error 0 28 Percent Surface Runoff 16 20 Average Annual Surface Loading Volume ac ft yr TSS lbs yr FSP lbs yr TP lbs yr SRP
162. ources by inhibiting or reducing mobilization and transport of pollutants with storm water e Storm Water Treatment SWT SWT removes pollutants of concern after they have entered concentrated storm water runoff flow paths This might include treatment of flows infiltrated to groundwater as well as those discharged to surface waters The PLRM streamlines and automates many of the data inputs required to setup and execute a simulation The PLRM is intended to minimize the burden on the end user for data collection and data compilation For example the PLRM automatically generates location specific PLRM User s Manual 4 December 2009 meteorological data needed for the long term continuous simulation based on user input With some minor exceptions performing a PLRM simulation only requires data typically collected and compiled in current Tahoe Basin practice for implementing storm water quality improvement projects 1 e Formulating and Evaluating Alternatives SWQIC 2004 The PLRM is intended to standardize the methods used to estimate pollutant loads for urban areas in the Lake Tahoe Basin The PLRM reports the pollutants of concern defined by the Lake Tahoe TMDL specifically TSS fine sediment particles lt 16 microns total and dissolved phosphorus and total and dissolved nitrogen Hydrologic Simulation including hydrologic source controls Pollutant Load Generation including pollutant source controls o Storm Water Treatment
163. ous steps If you complete data entry in the Catchment Properties Editor but then decide to go back and edit one of the intermediate steps e g edit land uses in Step 2 the PLRM will require you to reconfirm and re enter data in subsequent steps PLRM User s Manual EN Catchment Properties Editor Catchment Properties Mame Catchi Flows To Outtalll Outtall1 DOrvBasinl Additional Attributes Step 2 Define Land Uses Lake Tahoe FLAM v1 0 Figure 5 1 Catchment Properties Editor 44 December 2009 There are five steps for data entry in the Catchment Properties Editor Steps 1 through 3 are described in this section of the Manual Input parameters described in this section are typically developed during the Formulating and Evaluating Alternatives FEA process and are available within a project s Existing Conditions Analysis Memorandum ECAM Therefore the methods to develop input parameters for Steps 1 through 3 are not described in detail here The formulation of alternatives should also include the input parameters described in this section if alternatives change catchment boundaries relative to existing conditions or if alternatives change land uses Key Concept Box A hyperlink to each step is provided below The sequence of data entry within the Catchment Properties Editor e Step 1 Define Physical Attributes is forced by the PLRM because e Step 2 Define Land Uses l input data in subsequent step
164. ovides a suggested default value Of 0 2 inches hour for infiltration rates as an estimate of the characteristic long term performance of infiltration in a Dry Basin When modifying the suggested default value the user should ensure that a characteristic value 18 provided and not an optimal value A characteristic value is defined as the average expected condition of the Dry Basin over the life span of the Dry Basin while factoring in assumptions for anticipated or committed maintenance NRCS U S Department of Agriculture 2007 National Engineering Handbook Part 630 Hydrology Chapter 7 Hydrologic Soil Groups PLRM User s Manual 129 December 2009 Infiltration in an Infiltration Basin Flagged As Range Message Reference Guidance Warning Low 0 05 in hour High 1 5 in hour Infiltration in an Infiltration basin is calculated based on the infiltration rate of the Infiltration Basin and the footprint of the Infiltration Basin Unlike pervious drainage areas and HSCs infiltration in an Infiltration Basin 1s not calculated based on Ksat but is directly specified by the user as an infiltration rate An infiltration rate below the minimum recommended range indicates that an Infiltration Basin is not functioning for infiltration Similar to HSCs an infiltration rate above the maximum recommended range should be justified as a hydraulically loaded Infiltration Basin may not perform above the recommended maximum over the
165. ppendix B of the Model Development Document describes how CRCs were developed and related to Pollutant Potential scores for each pollutant of concern RoadPollutantPotential Description Values in this table are used to relate Road Risk a road shoulder stabilization score and a road abrasive application score to a Pollutant Potential score Structure The Road Conditions Editor interacts dynamically with this table to continuously update Pollutant Potential based on user entry in the Road Conditions Editor The PLRM queries this table for 1 Road Risk column RdLandUseAndRisk 2 Road Stabilization Score RdStabScore and 3 Abrasive Application Score column AbrAppScore to return a unique Pollutant Potential Score column PollutantPotential The Pollutant Potential score is related to the CRCs in the table RoadCRCs Reference See Section 5 1 and Appendix B of the Model Development Document describe how Pollutant Potential relates to Road Risk road shoulder stabilization and abrasive applications PLRM User s Manual 143 December 2009 Simulation Period Description This table defines the Start Date and End Date for a Short Simulation and Full Simulation The user selects the simulation period from the Project Editor Structure The fields in this table are used to populate blank fields in the Options table based on user entry in the Project Editor Reference See Section 3 1 of this Manual Snowmelt Description This table incl
166. r SWTs are not explicitly linked to design information the user enters in the PLRM A drain time less than the recommended minimum will increase the capture efficiency of the SWT facility but will not consider how decreased hydraulic residence time may decrease treatment performance for surface runoff exiting the SWT If a user enters a custom volume discharge curve the brim full draw down time is calculated and reported to the user See Section 9 131 December 2009 HRT of a Wet Pool Flagged As Range Message Reference Guidance PLRM User s Manual Warning Low 24 hours High 96 hours The hydraulic residence time HRT of the wet pool is calculated as the Wet Pool Volume Average Baseflow Runoff leaving the wet pool through treatment outlets 1s assigned a CEC for each pollutant of concern Values below the recommended minimum HRT are not suggested because the modeling approach assumes the minimum hydraulic residence time is needed to produce the default CECs used in the PLRM No recommended maximum is necessary but a limit of 96 hours was set to indicate that increased performance may not be realized for HRTs greater than four days The recommended minimum HRT of 24 hours was selected based on best professional judgment to avoid user input that might over predict actual Wet Basin performance see Guidance below The minimum HRT of 24 hours for the wet pool reduces the potential for performance in a Wet Basin t
167. r are PLRM to run on your computer Access 2007 does not need to be a After extracting the content from the installed to run the PLRM The PLRM_Setup zip file to your computer PLRM setup program includes the free software Microsoft Access Runtime 2007 which needs to be installed for the Runtime PLRM to run and successfully b Follow the instructions on the screen to interact with the PLRM run the setup program AccessRuntime exe from within the folder Install Access install the free software Microsoft Access Database Runtime 2007 The setup program will automatically create a program group called PLRM The program group will be listed under the Programs menu which is under the Start menu The PLRM icon will be contained within the PLRM program group The PLRM executable can be found in the directory C Program Files PLRM Engine Note that if you have administrative access limitations on your computer you should ask your computer administrator to give you write access to the directory C Program Files PLRM on your computer when your administrator installs the PLRM PLRM User s Manual 7 December 2009 Having write access to the C Program Files PLRM will allow you to manage files better because certain file management functions are have not been developed into PLRM Version 1 see Section 3 3 Hardware Requirements This version of the PLRM will run on a computer that has the following e Intel Based PC or compatible
168. r each pollutant of concern can be reviewed in the Model Development Document in Section 5 Appendix A and Appendix B Pollutant Delivery Factors Pollutant Delivery Factors provide a method to adjust the quantity of pollutants of concern delivered to the outlet of the catchment This option was included in the Road Conditions Editor recognizing that the Road Methodology does not account for every PSC action that may be implemented to improve the quality of runoff generated from roads The intent of Pollutant Delivery Factors is to provide a flexible and transparent process for adjusting pollutant loads if the Road Methodology is deemed insufficient for representing PSCs By default Pollutant Delivery Factors are set to 1 in the Road Conditions Editor Changing a Pollutant Delivery Factor to a value other than 1 will linearly adjust CRCs for pollutants of concern Two Pollutant Delivery Factors are provided to separately adjust 1 Particulate CRCs TSS TP and TN and 2 Fines and Dissolved CRCs FSP SRP and DIN Adjusting Pollutant Delivery Factors to a value other than 1 is acceptable but the adjustment will be flagged by the Recommended Range Report because the user should provide justification to project reviewers when Pollutant Delivery Factors other than are used PLRM User s Manual 67 December 2009 6 2 Parcel Methodology The Parcel Methodology defines the level of Best Management Practices BMP implementation as defined by TRP
169. r requires entry of information about the catchment in a series of steps Information entered from one step is used to populate recommended default values and inputs parameters in subsequent steps Thus the steps must be completed sequentially As shown in Figure 2 8 when you first access the Catchment Properties Editor Step 3 through Step 5 will not be active and cannot be selected The sequence of data entry is forced by the PLRM since input data in subsequent steps is contingent upon input data entered in previous Steps Until all five data entry steps have been completed only the Cancel button and Apply button will be active in Catchment Properties Editor The OK button will become active once all five steps have been completed The functions of each button are as follows Cancel disregards changes and returns to the Schematic Window Apply saves input parameters for a particular step such as Step 1 Define Physical Attributes e OK saves input parameters for all steps in Catchment Properties Editor and returns to the Schematic Window PLRM User s Manual 16 December 2009 BN Catchment Properties Editor Catchment Properties Blame Catchl Flows To ln Additional Attributes Step 3 Define Soils Step 4 Define Land Use Conditions Step 5 Define Drainage Conditions Lake Tahoe PLAM v1 0 Figure 2 8 Catchment Properties Editor The first requirement in the Catchment Properties Editor is to define the receiving ob
170. r this Project you can use Windows Explorer to navigate to the appropriate directory named Project1 Note that the PLRM must be closed when deleting a Project Folder or Scenario Folder EEG Project and Scenario Manager Ea 50 100 MFR50 Big MER CICU Pervious E FlatStreets Spaces Work New Project amp CRC a Project or Scenario Files at C PLRM Projects Project1 Lake Tahoe PLRM v1 0 Figure 3 4 Finding Project and Scenario Folders on Your Computer You can view edit or print files created by the PLRM by browsing to the associated Project or Scenario Folder A complete list of file types created by the PLRM and their functions are described in Section 2 of the PLRM Model Development Document PLRM User s Manual 40 December 2009 4 0 Developing a Schematic The Schematic Window is the central input form for the PLRM Figure 4 1 illustrates the functions of the buttons on the Schematic Window Return to Compa re Projectand Scenariosto View Export About Functi Scenario Save Run Estimate Load Scenario Scenario PLRM MSIE neat i i i i iew Toolbar Toolbar Manager Scenario Scenario Reductions Report Report Version Le Lake Tahor PLRM 1 0 Project Name DefaultProject Scenario Nan gt DefaultSce nario Project Manager 443 Save fe Run Y Compare Scenarios li View Report DP xport Report About a fc A TE 2 lt Create a Catchment Object _ Junction Selection
171. ration of the storm water entering the Treatment Vault The Treatment Vault Editor allows for modification of CECs values With supporting effluent quality data a user may modify CEC values in the Treatment Vault Editor and model any flow based SWT facility PLRM User s Manual 105 December 2009 8 7 Outfalls Junctions and Flow Dividers Outfalls Junctions and Flow Dividers are hydrologic routing objects in the PLRM Outtfalls define the final discharge point s for a Scenario and are required objects for any PLRM Scenario Junctions can be used to combine flows prior to routing to a downstream object Flow Dividers can be used to split flows Junctions and Flow Dividers are optional objects for any PLRM Scenario Below is a brief discussion of each object Outfall Editor To access the Outfall Editor add an Outfall to the Schematic Window and double click on the Outfall icon This will bring up the Outfall Editor as shown in Figure 8 17 0 ES Outfall Editor Outfalls Name Outfall2 Figure 8 17 Outfall Editor The only item to edit for an Outfall is the name By default the PLRM will name Outfalls in a Scenario sequentially as Outfall 1 Outfall2 etc Key Concept Box Outfalls are required objects in any PLRM simulation because the PLRM calculates and summarizes average Outfalls are equir ed objects in annual runoff volumes and pollutant loading for a any PLRM simulation because the PLRM calculates a
172. rawdown time for a Dry Basin is 48 hours PLRM User s Manual 112 December 2009 Scenario Summary The Scenario Summary section summarizes average annual hydrology and surface loading The hydrology summary includes average annual precipitation evaporation losses system surface discharge and percolation to groundwater The summary also calculates a water balance continuity error and the percent of rainfall that generates surface runoff The surface loading summary provides average annual runoff volumes and pollutant loading for each outfall in the Scenario as well as Scenario Total The Scenario Total is simply the sum of the runoff volumes and pollutant loads for all outfalls in the Scenario The Scenario Total is used by the Scenario Comparison Report to estimate pollutant load reductions among Scenarios PLRM User s Manual 113 December 2009 9 2 Scenario Comparison Report After more than one Scenario within a Project has been successfully simulated comparisons among Scenarios may be made to estimate pollutant load reductions or compare effectiveness of storm water improvement alternatives Estimating a load reduction would typically involve comparing one or more improvement Scenarios to a baseline condition such as an existing conditions Scenario To access the Scenario Comparison Report Figure 9 3 click on the Compare Scenarios button in the Function Compare Scenarios ly Toolbar from the Schematic Window EN Scenario Compa
173. risons SE y aeo o Scenario Comparision Step 1 Select Project Step 2 Select Baseline Scenario Project1 Project1 Scenariol Scenariol Available Scenarios with Results Compared to Baseline Scenario2 Scenarioz Scenarios Scenarios Runoff Volume and Pollutant Load Reduction Runoff Average Annual Loads lbs Yolume Scenario ac ft T55 FSP TP SRP Scenarioe 2 5 390 6 Scenarios 4 6 1868 2 Relative Differences Absolute Differences Average Annual Load Reduction 0 Runoff Note ve Reduction ve Increase 5 Yolume cenario ac ft FSP TP SRP Scenariol eel 476 35 56 6 1 9 ds 3 1 Scenarioz 9 3 5 47o 3 2 5 3 0 0 0 0 Scenarios 112 1 330 3 201 6 263 2 208 3 204 8 Figure 9 3 Scenario Comparison Report Only Scenarios within the same Project may be compared However any Project with completed Scenarios may be assessed at any time by accessing the Scenario Comparison Report To compare Scenarios for a Project complete the following steps in order 1 In the drop down box titled Step 1 Select Project select a Project After selecting the Project you ll notice that Scenarios associated with that Project with completed simulations will appear in the selection box titled Available Scenarios and Results PLRM User s Manual 114 December 2009 2 In the drop down box titled Step 2 Select Baseline Scenario select a Baseline Scenario that all other Sce
174. rom the Volume Discharge Curve Editor e Save and Close informs the user of calculated average Filtration Rate based on values entered for each volume increment Information entered in the form is saved and the PLRM returns to the Bed Filter Editor e Auto Calculate restores the values of Filtration Rate based on the design parameters entered from the Bed Filter Editor The default is a constant filtration rate for all storage volume increments greater than zero e Cancel disregards changes to the form and returns to the Bed Filter Editor PLRM User s Manual 100 December 2009 PLRM User s Manual Volume Discharge Curve Editor Note Changing these values will overwrite any previously entered values for drawdown time or infiltration rate volume tcf T aa Arr RO 599 990 Daa ts 1111 111 1500 009 1666 66 1944 444 Cde 00 Lake Tahoe PLAM v1 0 Filtration Rate inf hr O 1 1 Save and Close Auto Calculate Cancel Figure 8 12 Bed Filter Volume Discharge Curve Editor 101 December 2009 8 5 Cartridge Filter A Cartridge Filter is a flow based SWT that typically houses a number of proprietary cartridges that contain engineered filtration media Cartridge filters provide pollutant load reductions by removing particulates and associated pollutants from storm water through physical straining and adsorption While some storage is often prov
175. rrent CEC values are based on a statistical analysis of best available data from multiple storm water performance studies for each type of SWT facility included in the PLRM The statistical nature of the analysis is assumed to provide a representative performance estimate for each SWT facility Justification should be provided if the default CEC values are replaced using data from a single storm water performance study For example 1f the design of the proposed facility 1s very similar to the design of a monitored facility the performance of the two may be expected to be comparable assuming similar drainage characteristics and climatic conditions However the user should be cautious about using data from relatively short term studies 134 December 2009 11 0 PLRM Database Overview The PLRM Database 1s a Microsoft Access 2007 database used to 1 store Default Parameters and preprocessed input data 2 store program configurations and 3 dynamically generate several PLRM Interface components and Input Parameters based on user entry The PLRM Database significantly reduces the data preparation and data input burden on the user relative to typical requirements for building a continuous simulation model of hydrology and pollutant loading The typical user of the PLRM does not need to interact directly with the PLRM Database The PLRM Database was designed to provide an application that is simple to use while allowing flexibility for future database
176. rson or organization developing the Scenario Scenario Name name of the Scenario when viewed within the PLRM Interface Changing the default name of the Scenario from the PLRM Interface will not change the default name of the Scenario Folder on your computer see Section 3 3 Scenario Notes the box below the Scenario Name field allows for a longer description of the Scenario to be entered EN Scenario Editor Project Information EIP Number if applicable A Implementing Agency Po Project Location Description A Project Location Grid No Continous Simulation Length Short Simulation Full Simulation Scenario Information Scenario Name Scenario 1 Lake Tahoe PLAM v1 0 Figure 3 3 Scenario Editor PLRM User s Manual 38 December 2009 The following functions are executed by the Scenario Editor Back Returns to the Project and Scenario Manager Next Proceeds to the Schematic Window where you can start building a PLRM Scenario If you Key Concept Box select a new meteorological grid cell in the Project Editor when you click the NEXT button on the The PLRM executes an algorithm to create hourly time series data of precipitation and temperature for your project location This Scenario Editor a message will pop up explaining that the long term meteorological data for the selected grid cell needs to be created Creating the operation will take up to five hourly time series of precipitation a
177. s CRCs for each land use e Section 7 Defining Hydrology and Hydrologic Source Controls Describes how to enter input parameters and edit default parameters for hydrologic properties of drainage areas and for defining hydrologic source controls e Section 8 Defining Storm Water Treatment Facilities Describes how to enter and edit input parameters to define the function of Storm Water Treatment facilities e Section 9 Viewing Results Describes how to access and interpret results of a PLRM simulation for a single scenario and for comparing multiple scenarios e Section 10 Input Parameter Guidance Provides a description of the most sensitive input parameters in the PLRM provides guidance for estimating sensitive input parameters and documents the recommended ranges for sensitive input parameters e Section 11 Database Overview Provides an overview of the structure of the PLRM database e Section 12 Notes on PLRM Modeling Describes some key limitations of the model PLRM User s Manual 3 December 2009 1 4 Modeling Approach and Capabilities Figure 1 1 illustrates the three elements used for simulating pollutant loads in the PLRM 1 hydrology and hydrologic source controls HSC 2 pollutant load generation and pollutant source controls PSC and 3 storm water treatment SWT User input is required for each element and the results derived from each element are used in subsequent elements Computed pollutant load
178. s is e Step 3 Define Soils contingent upon input data e Step 4 Define Land Use Conditions is entered in previous steps If you described in Section 6 of this Manual complete data entry in the Catchment Properties Editor but then decide to go back and edit one of the intermediate steps e g edit land uses in Step 2 the Until all five data entry steps have been completed only PLRM will require you to the Cancel button and Apply button will be active in reconfirm and re enter data in Catchment Properties Editor The OK button will subsequent steps become active once all five steps have been completed e Step 5 Define Drainage Conditions described in Section 7 of this Manual The functions of each button are as follows e Cancel disregards changes and returns to the Schematic Window e Apply saves input parameters for a particular step such as Step 1 Define Physical Attributes e OK saves input parameters for all steps in Catchment Properties Editor and returns to the Schematic Window 5 1 Physical Attributes Physical attributes include the storm water routing of the catchment the size of the catchment and the average slope of the catchment The following are input parameters for Step 1 e Name you can edit the default name of the catchment if desired By default the PLRM will name catchments sequentially as Catch1 Catch2 etc PLRM User s Manual 45 December 2009 e Flows to contains a drop
179. s represent the combined effectiveness of the three major elements A detailed rationale for the modeling approach is discussed in the report Methodology to Estimate Pollutant Load Reductions nhc and Geosytnec 2006 The definition of each element is as follows e Hydrology and Hydrologic Source Controls HSCs Hydrology is reported as average annual runoff volumes from long term continuous simulations of precipitation and runoff Continuous hydrologic simulations include many time steps over a specified period of time including many hydrologic events and intervening dry periods rather than a single storm to represent the full range of hydrologic conditions during the period of time simulated HSCs reduce runoff volumes and minimize the concentration of storm water runoff through distributed runoff interception infiltration and disconnection of impervious surfaces HSCs primarily function to increase infiltration which routes precipitation or surface runoff to groundwater e Pollutant Generation and Pollutant Source Controls PSCs Pollutant generation focuses on estimating the total pollutant load from a drainage catchment based on the characteristics of the catchment in particular the land uses with the catchment and the condition of the land uses The product of storm water volume and storm water pollutant concentration is the pollutant load generated from the catchment PSCs reduce the generation of pollutants of concern at their s
180. s than the Surcharge Storage CECs are never lower than the Wet Basin CECs Customized Treatment Rate The Wet Basin Editor provides a function that allows the user to customize the Treatment Rate of the Surcharge Storage as a function of the Surcharge Basin Volume to account for complex outlet designs or variable stage area relationships This function can be accessed by clicking on PLRM User s Manual 96 December 2009 the Custom Volume Discharge Curve button from the Wet Basin Editor Figure 8 7 Clicking on the button will activate the Volume Discharge Curve Editor Figure 8 9 The column Volume cf divides the user defined Surcharge Basin Volume entered in the Wet Basin Editor into ten increments For each increment the user can set the Treatment Rate cfs of the Surcharge Basin Volume of the Wet Basin The Treatment Rate cfs 1s surface runoff that drains through the treatment outlet s of the Surcharge Storage The following functions can be performed from the Volume Discharge Curve Editor e Save and Close informs the user of calculated Brim Full Draw Down Time based on values entered for each volume increment Information entered in the form is saved and the PLRM returns to the Wet Basin Editor e Auto Calculate restores the values of Treatment Rate based on design parameters entered from the Wet Basin Editor e Cancel disregards changes to the form and returns to the Wet Basin Editor Volume Discharge Curve Edi
181. ser s Manual 142 December 2009 PrecipTimeSeries Description This table includes an 18 year data set Water Year 1989 to 2006 of precipitation for eight SnoTel gages in the Tahoe Basin Data is provided as depth in inches on hourly intervals Data is only for hours when precipitation is recorded SWMM 5 assumes missing hours are periods without precipitation Structure The columns in the table are formatted so the time series can be exported and read directly as a SWMMS input file for precipitation The column SnoTellD is the code identifying the SnoTel station The column Precip is the depth of precipitation recorded at that SnoTel station for the specific hour in units of inches Reference See Section 3 of the Model Development Document RoadCRCs Description This table includes characteristic runoff concentrations CRCs for pollutants of concern for Road Land Uses which are related to the calculation of Pollutant Potential Pollutant Potential is determined through user input in the Road Conditions Editor and the database table RoadPollutantPotential Structure For each pollutant of concern the table repeats Pollutant Potential scores in one tenth increments from 0 5 to 5 A CRC is assigned to each Pollutant Potential score for each pollutant of concern These CRC values are dynamically read into the Road Conditions Editor based on the Pollutant Potential Score calculated by the Road Conditions Editor Reference Section 5 1 and A
182. sign Parameter to simulate the performance of the Cartridge Filter for capturing and treating storm water runoff e Maximum Treatment Flow cfs the maximum flow rate through the Cartridge Filter that provides effective treatment For proprietary devices a unit rate is typically specified per cartridge that can be used to estimate the total treatment rate of the device An illustration of how the Design Parameters relate to the conceptual representation of a Cartridge Filter in the PLRM is accessible from the Cartridge Filter Editor by clicking on the link Click here to see schematic with parameters descriptions Clicking on the link will bring up Figure 8 14 Bypass Flow Inflow 50050 Treated Flow Maximum Treatment Flow Figure 8 14 Cartridge Filter Representation in PLRM As shown in Figure 8 14 storm water that passes through the filter media is considered Treated Flow Bypass Flow occurs when the incoming flow rate exceeds the Maximum Treatment Flow The quality of Treated Flow from the Cartridge Filter is assigned CECs for pollutants of concern as defined in the Cartridge Filter Editor The quality of Bypass Flow is equal to the influent concentration of the storm water entering the Cartridge Filter The Cartridge Filter Editor allows for modification of CEC values but any modification should be justified by the user PLRM User s Manual 103 December 2009 8 6 Treatment Vault or User Defined Flow Based SWT
183. surface water by infiltration is tracked by the PLRM Storm water that bypasses the Infiltration Basin through the bypass outlet when the Water Quality Volume is exceeded is considered Bypass Flow The quality of Bypass Flow is equal to the influent concentration of the storm water entering the Infiltration Basin Note that Infiltration Basins do not include a treatment outlet Hence there are no CECs for Infiltration Basins and treatment is assumed to only occur via volume reductions from infiltration Customized Infiltration Rate The Infiltration Basin Editor provides a function that allows the user to customize the Infiltration Rate as a function of Water Quality Volume to account for head dependent infiltration rates or variable stage area relationships This function can be accessed by clicking on the Custom Volume Discharge Curve button from the Infiltration Basin Editor Figure 8 4 Clicking on the button will activate the Volume Discharge Curve Editor Figure 8 6 The column Volume cf divides the user defined Water Quality Volume entered in the Infiltration Basin Editor into ten increments For each increment the user can set the Infiltration Rate in hr of the Infiltration Basin The following functions can be performed from the Volume Discharge Curve Editor e Save and Close informs the user of calculated average Infiltration Rate based on their values entered for each volume increment Information entered in the form is saved
184. tageous to use two or more catchments into two or more catchments In the Drainage Conditions Editor the user is required to enter the hydrologic properties that most strongly influence calculations of surface runoff in the PLRM The discussion in the following section describes entry of information in the PLRM for a single catchment This simplifies the text but is not a limitation of the PLRM There is no limitation on the number of catchments that can be simulated in a Scenario in the PLRM PLRM User s Manual 72 December 2009 7 1 Drainage Conditions For each urban land use Drainage conditions are defined by estimating the portions of a land use routed to the catchment outlet or to an HSC facility where an HSC facility can either be an Infiltration Facility or a pervious area where storm water runoff is dispersed termed a Pervious Dispersion Area Defining Drainage Conditions based on the routing of storm water for a particular land use is termed Land Use Routing in the PLRM Land Use Routing allows the PLRM to account for flow volume reductions associated with Hydrologic Source Controls HSCs implemented for a specific land use The methods used to define Drainage Conditions are not Key Concept Box intended to require a detailed tabulation in GIS or AutoCAD The user should estimate the general The methods used to define characteristics by land use e g does 0 25 50 75 Drainage Conditoins are not intended to require a
185. teristics that are assumed to most strongly influence the quality of storm water generated specifically Slope Traffic Density and Adjacent Land Use Scenario a unique PLRM simulation associated with a specific Project A Scenario typically represents existing conditions or a potential water quality improvement alternative The comparison of Scenarios within a Project produces an estimate of pollutant load reduction Multiple Scenarios are associated with a single Project e g Existing Conditions Alternative 1 Alternative 2 etc Storm Water Treatment SWT facilities that remove pollutants of concern after they have entered concentrated storm water runoff flow paths This might include treatment of flows infiltrated to groundwater as well as those discharged to surface waters SWT facilities in the PLRM include a Dry Basin Infiltration Basin Wet Basin Bed Filter Cartridge Filter and Treatment Vault Treatment Vault a generic flow based SWT facility where treatment may occur via multiple treatment processes The default CECs for Treatment Vaults are based on storm water performance data for hydrodynamic separators a proprietary type of Treatment Vault Treatment Vaults are considered flow through devices in the PLRM and storage is considered to be negligible PLRM User s Manual 153 December 2009 Wet Basin a class of volume based SWT that includes a permanent or seasonal pool of water typically called a wet pool
186. the Dry Basin Editor Set the Infiltration Rate to equal 0 2 and then click the OK button to save and return to the Schematic Window Now run the PLRM by selecting the Run button Once the simulation has completed click on the Compare Scenarios button in the Function Toolbar Figure 2 6 from the Schematic Window This will bring up the Scenario Comparison Report Figure 2 19 PLRM User s Manual Scenario Comparisons Scenario Comparision Step 1 Select Project Step 2 Select Baseline Scenario Project1 Project11 Scenario1 Scenario1 Available Scenarios with Results Compared to Baseline Scenario2 Scenario2 Runoff Volume and Pollutant Load Reduction Runoff Average Annual Loads lbs A Yolume Scenario ac ft yr TSS FSP TP SRP Scenariol 4 6 687 4 429 1 3 6 1 0 Scenario2 3 1 494 8 302 4 2 5 0 7 Relative Differences Absolute Differences Average Annual Load Reduction Runoff Note ve Reduction ve Increase Volume Scenario Cac ft yr TSS FSP TP SRP TN DIN Scenariol 4 6 687 4 429 1 3 6 1 0 16 2 1 9 Scenario2 30 7 28 0 29 5 30 6 31 3 30 3 Figure 2 19 Scenario Comparison Report 32 December 2009 To compare Scenarios for our Project complete the following steps in order 1 In the drop down box titled Step 1 Select Project select our Project After selecting the Project you ll notice that our Scenarios will appear in the selection box title
187. the object that receives flow from the Treatment Vault Objects may include junctions outfalls dividers or another SWT Only previously created objects in the Schematic Window will be available to select from the drop down box Design Parameters The Treatment Vault Editor requires entry of a single key Design Parameter to simulate the performance of the Treatment Vault for capturing and treating storm water runoff e Maximum Treatment Flow cfs the maximum flow rate through the Treatment Vault that provides effective treatment For proprietary devices design guidelines or manufacturer guidelines can be used to determine the maximum treatment flow An illustration of how the Design Parameters relate to the conceptual representation of a Treatment Vault in the PLRM is accessible from the Treatment Vault Editor by clicking on the link Click here to see schematic with parameters descriptions Clicking on the link will bring up Figure 8 16 Bypass Flow Inflow i Treated Flow Maximum Treatment Flow Figure 8 16 Treatment Vault Representation in PLRM As shown in Figure 8 16 storm water that passes through the vault is considered Treated Flow Bypass Flow occurs when the incoming flow rate exceeds the Maximum Treatment Flow The quality of Treated Flow from the Treatment Vault is assigned CECs for pollutants of concern as defined in the Treatment Vault Editor The quality of Bypass Flow is equal to the influent concent
188. the option to create a shortcut on your desktop If you decide to create a shortcut the icon on your desktop will look like Figure 2 1 P L R M PLRM v1 0 Figure 2 1 PLRM Icon From your desktop double click on the PLRM icon If you did not create a PLRM icon on your desktop go to the Start menu and select Programs then select PLRM When you first start the PLRM you will see the Project and Scenario Manager as shown in Figure 2 2 The PLRM Schematic Window will be visible in the background but will not be accessible to you at this point PLRM User s Manual 9 December 2009 Ea Lake T ahoe PLRM 0 Project Name DefaultProject Scenario Name DefaultScenario Project Manager 43 Save E Run A Compare Scenarios li View Report LD xport Report B About E EN Project and Scenario Manager amp k amp LO gt OO8 seeeeeans e E Double Click on a Project Scenario to Begin Copy Selected New Project Lake Tahoe PLRM v1 0 Figure 2 2 Starting the PLRM 2 1 Starting a New Project and Scenario The first step in developing a PLRM simulation is to define a new Project and a new Scenario In PLRM terminology a Project 1s the physical area where storm water quality improvements and the potential for pollutant load reduction will be assessed A Scenario is a unique PLRM simulation that can represent existing conditions or a water quality improvement alternative Multiple Sce
189. tions Additional input parameters can be used in the Road Conditions Editor see below to further refine pollutant potential in each Road Risk category Table 6 1 Criteria for Default Road Risk GIS Layer Primary Roads Primary Road Average Low Slope Moderate Slope High Slope Annual Daily Traffi a lt 3 3 7 gt 7 Low Average Annual Daily Traffic lt 10 000 AADT High Average Annual Daily Traffic gt 10 000 AADT Secondary Roads Dominant Land Use Low Slope Moderate Slope High Slope A e 3 Do TH The following guidelines can be followed to adjust Road Risk for factors that were not incorporated into the GIS analysis The factors listed below might justify increasing Road Risk for individual road segments relative to the defaults provided in the Road Risk GIS Layer You can also decrease Road Risk categories relative to default values 1 Primary access roads for ski resorts or other large commercial or recreational facilities 2 School bus routes 3 Secondary Roads that contain above average road traffic such as roads that access a large neighborhood or other major throughways PLRM User s Manual 54 December 2009 4 Intersections of Secondary Roads with Primary Roads 5 Roads that are predisposed to icy conditions and are managed frequently for safety 6 1 2 Road Conditions To access the Road Conditions Editor Figure 6 3 within the Land Use Conditions Editor click on the button Edit Road Co
190. to represent Tahoe Basin conditions Pre load input data sets include e Long term meteorological data sets of precipitation and temperature at hourly intervals e Snowmelt and snow management parameters e Evapotranspiration parameters e Hydrologic properties of soil from the Tahoe Basin Soil Survey NRCS 2006 Pollutant Generation and Pollutant Source Control PSC Pollutant generation in the PLRM is based on the product of average annual runoff and land use based characteristic runoff concentrations CRCs Two separate methods are used to represent the implementation of PSCs which can reduce the CRCs for 1 public right of ways Road Methodology and on 2 predominantly private land uses Parcel Methodology Capabilities for simulating pollutant generation and PSC implementation in the PLRM include e Road Methodology a standardized approach that integrates physiographic characteristics pollutant source control efforts and pollutant recovery to predict the likely road condition and associated CRCs e Parcel Methodology a simple method to estimate improvements in CRCs from private property BMP implementation consistent with current regulations Storm Water Treatment SWT The reduction in pollutant loading achieved by a SWT facility depends on the portion of runoff treated and the extent of treatment achieved The modeling approach calculates the percentage of runoff captured by the SWT from user entered design information and long
191. tor Note Changing these values will overwrite any previously entered values for drawdown time or infiltration rate Treatment Rate crs O 0 01447 0 01447 0 01447 0 01447 0 01447 0 01447 0 01447 0 01447 Save and Close 0 01447 Auto Calculate 0 01447 Cancel Lake Tahoe PLAM v1 0 Figure 8 9 Wet Basin Volume Discharge Curve Editor PLRM User s Manual 97 December 2009 8 4 Bed Filter A Bed Filter is a flow based SWT designed for vertical filtration of storm water through a porous medium such as sand compost zeolite or combinations of natural and engineered substrates Bed filters provide pollutant load reductions by removing particulates and associated pollutants from storm water through physical straining and adsorption Some storage 1s typically designed above the media bed that temporarily ponds storm water when the rate of inflowing storm water is greater than the rate of filtration through the media Treated storm water is collected in an underdrain system and routed as surface flow To access the Bed Filter Editor add a Bed Filter to the Schematic Window and dh double click on the Bed Filter icon This will bring up the Bed Filter Editor as b shown in Figure 8 10 EN Bed Filter Editor Bed Filters obs TY Edit Object Mame BedFilter 1 Flows To Design Parameters Custom Yolume Discharge Curve Parameters Default Value User Value Equalization B
192. uded in the table are defined by the TMDL Land Use GIS Layer which can be downloaded from the Lahontan LRWQCB website http www waterboards ca gov lahontan water_issues programs tmdl lake_tahoe index shtml PLRM User s Manual 140 December 2009 MetGrid Description The table includes data sets for each meteorological grid cell used in the meteorological extrapolation Structure Each row in the table is a unique meteorological grid cell and includes the assigned SnoTel gage monthly scaling factors for precipitation average elevation of the grid cell in the Tahoe Basin and a temperature adjustment based on the difference in elevation between the assigned SnoTel gage and the average elevation of the grid cell A description of each field can be reviewed by opening the table in Design View in Access Reference See Section 3 of the Model Development Document MonthlyWindSpeed Description This table includes the monthly average windspeed used by the heat budget equation for SWMMS to calculate snowmelt during periods with precipitation Structure Wind speed values are input as monthly normal values in units of mph Reference Default values are average values for the Tahoe Basin taken from the Fifth Generation Mesoscale Model MM5 which was used by researchers at UCDavis to predict meteorological variables for the Tahoe Basin nodeValidationRules Description The table includes default recommended ranges for key Input Parameters
193. udes snowmelt parameters for the temperature index method used by SWMMS to compute snowmelt Structure A description of each field can be reviewed by opening the table in Design View in Access The column ElevationAboveMSL is blank because the elevation is populated based on the meteorological grid cell the user defines in the Project Editor Elevation is read from the MetGrid table Reference See Section 4 3 of the Model Development Document Snowpacks Description This table includes snowmelt parameters for the temperature index method used by SWMMS5 as well as parameters used by the SWMM5 snow management algorithm Structure The table includes values for minimum and maximum melt coefficients snow management coefficients etc Three separate snowmelt routines are included in the table The three separate snowmelt routines are applied as follows to land uses in the PLRM 1 Roads applied to Road Land Uses 2 Parcels applied to Single Family Residential Multi Family Residential and CICU 3 Pervious applied to all other land uses Each routine is organized in the formatting required by the SWMMS3 code which includes four rows of data entry 1 Row 1 defines the melt coefficient for plowable surfaces 2 Row 2 defines the melt coefficient for impervious surfaces not plowed 3 Row 3 defines the melt coefficient for pervious surfaces 4 Row 4 defines plowing characteristics PLRM User s Manual 144 December 2009 A des
194. ughly 10 100 acres However there are no restrictions applied in the PLRM on the size of a project area that can be modeled or to the size of a catchment that can be modeled That said the user should be aware of the following when simulating catchments that are smaller or larger than the recommended size l PLRM Small catchments the PLRM was not developed with the intention of simulating pollutant loading from individual parcels e g 5 000 square feet to 1 acre parcels Theoretically there is nothing about the structure of the PLRM that would cause errors in a simulation of a single parcel However providing parcel scale assessments 1s not the intention of the PLRM and this functionality has not been robustly tested There is the potential for small scale analyses to produce inaccurate results examples of why this can occur are described below Small catchments can be simulated in the PLRM and the pollutant load and runoff generated from these catchments should be reasonable However the user should follow standard engineering methods to size flow based storm water treatment SWT facilities placed at the outlet of small catchments instead of sizing flow based SWT facilities based on PLRM results This is because a As the drainage area of a catchment decreases the time of concentration of the catchment will also decrease making peak flows in the catchment more sensitive to short duration high intensity precipitation b T
195. use within a catchment and for a specific Drainage Condition within that land use E Drainage Conditions Editor Catchment JD Catchi f Area Tac a Parcel Methodology Road Methodology Drainage Design Pery Impery Impery Dep Dep of Area Area DCIA Ksat Storage Storage Primary Roads 10 acres Area ac ac in hr in in Area Draining To Infiltration Facilities 0 100 0 06 01 0 02 Edit HSC Facility Edit HSC Facility Area Draining To Pervious Dispersion Areas 0 p 0 06 0 1 0 02 Remaining Area Draining To Outlet 100 0 06 0 1 0 02 Secondary Roads O acres Edit HSC Facilit Area Draining to Infiltration Facilitie Edit HSC Faciity_ Edit HSC Facility In this example for Primary Roads For the field DCIA enter the with the Drainage Area percentage of the 9 impervious Remaining Area Draining to acres that is directly connected to Outlet the PLRM has calculated drainage systems and therefore an impervious area of 9 acres the outlet of the catchment based on previous user input Lake Tahoe PLRM v1 0 Figure 7 2 Entering Hydrologic Properties for a Drainage Area The most recent guidance for estimating DCIA 1s found in Interim Guidance Paper for Formulating and Evaluating Alternatives for Tahoe Basin Water Quality Improvement Projects 2008 That Interim Guidance Paper can be downloaded at http www trpa org default aspx tabindex 4 amp tabid 168 PLRM Us
196. values for the parameters shown in Table 10 1 can be found in the PLRM Model Development Document and are not discussed here In general the Default Parameters included within the PLRM Database should not be modified by the user unless the modifications are done to incorporate new or additional data Maintaining consistent Default Parameters in the PLRM Database 1s recommended because 1t will help to maintain consistency of results generated by multiple user s across multiple project areas Snow Parameters Evaporation Rates Overland flow length Characteristic Runoff Concentrations CRCs Sweeping Effectiveness PLRM User s Manual Table 10 1 Sensitive Default Parameters within PLRM Database A Location in PLRM Influence on PLRM Parameter Description Database Output Includes snow melt coefficients the dividing temperature between rain and snow and the base temperature at which snow begins to melt Monthly estimates of evaporation rates Characteristic width of the overland flow path for sheet flow runoff Calculated for the user within the PLRM Database based on the area of each drainage catchment and a shape factor CRCs for parcel land uses and roads where Road CRCs are related to the condition of the road Estimate of the percent reduction in a CRC based on street sweeping practices 117 SnowMelt and SnowPacks Evaporation Defaults IDs 400 402 RoadCRCs and ParcelCRCs SweepingEffe
197. volumes and therefore this action will meet the definition of Hydrologic Source Controls HSCs in this Manual It is important to note that there are three ways to simulate implementation of HSCs in the PLRM among Scenarios within a Project 1 Land use changes that decrease the amount of impervious area Changes to impervious area are specified in the Land Use Editor 2 Routing some portion of impervious area from a land use to an HSC facility An HSC Facility in the PLRM 1s defined as either an Infiltration Facility or a Pervious Dispersion Area Changes in storm water routing to an HSC Facility are specified in the Drainage Conditions Editor using Drainage Areas PLRM User s Manual 75 December 2009 3 Disconnecting existing impervious area The concept of disconnected impervious area is different than Land Use Routing 1 e the HSC described above in 2 In this case storm water runoff is not purposely routed to an HSC facility but rather is deterred from becoming concentrated flow by allowing or promoting sheet flow from impervious surfaces to convey over pervious surfaces Changes to the amount of DCIA within a land use and Drainage Condition are specified in the DCIA field of the Drainage Conditions Editor Figure 7 2 below illustrates how the DCIA field in the Drainage Conditions Editor relates to the impervious area for a land use As shown in Figure 7 2 the user must enter hydrologic properties for a specific land
198. will The PLRM will simulate simulate performance of an SWT continuously over an 18 performance of an SWT year time period when the Full Simulation option is continuously over an 18 year selected from the Project Editor However the Input time period However the Input Parameters used to define the performance characteristics of the SWT are static and do not explicitly account for changes in activities or a lack of maintenance activities Therefore the condition over time such as Parameters used to define the performance characteristics of the SWT are static and do not explicitly account for changes in condition over time such as maintenance modeler must decide what the average expected condition maintenance activities or a lack of the SWT will be for each Input Parameter required by of maintenance activities the PLRM over the life span of the SWT while factoring in assumptions for anticipated or committed maintenance Section 10 2 of this Manual provides recommended ranges and guidance for key Input Parameters PLRM User s Manual 85 December 2009 8 1 Dry Basin A Dry Basin also known as an extended detention basin or dry pond is a volume based SWT designed to detain runoff for an extended period of time to allow particle and associated pollutant settling Dry basins provide pollutant load reductions from 1 volume reduction via infiltration and 2 improvements in effluent quality relative to influent quality Dry Basins do

(PLRM) User`s Manual - California Stormwater Quality Association

Contents

Download Pdf Manuals

Related Search

Related Contents