User`s Manual
Contents
1. Transverse gutter width The gutter width usually the lip of gutter Q Res SSIONAL Page 36 GROUP INC WinStorm 3 0 User s Manual Max allowed ponded The maximum allowed ponded width for traffic safety width Transverse slope 2 Additional cross slope to compute ponded width spread Transverse width 2 Additional cross width Approach Gutter in Sag Left and Right Left Approach Gutter in Sag Percent Discharge 100 os N gutter value oms Longitudinal Gutter Slope o 005 ftft Transverse Gutter width 5 f Transverse Gutter Slope 0 031 3 ft ft Max Allowed Ponded Width P2 _ ft Second Cross Section Data Transverse Slope2 fo ftt Transverse Width2 0 ft The information required is the same as with the previously described Gutter on Grade plus the following term Percent Discharge 100 The percent of flow coming from left and right side of the sag inlet Curb on Grade Curb On Grade Curb Lenath fi 5 ft Gutter Depression 0 25 ft Depression Width fis ft Curb Length The length of the curb inlet If null then the inlet will be designed Gutter Depression Gutter depression The a value from 0 to 6 inches QB Page 37 GROUP INC WinStorm 3 0 User s Manual Depression Width The width of depression in front of opening Usually the lip of gutter Curb in Sag Curb Length The length of the curb inlet If null then the inlet will be designed Gutter Depressio2. Q Q Grate Inlets in a Sag Sag inlets operate as a weir at low ponding depths and as an orifice at high ponding depths WinStorm uses an iterative process to calculate the inlet size needed for the existing flow regime The following equations describe capacity for a grate inlet when operating as a weir and as an orifice respectively weir flow O S3 P yr 3 for metric and 1 66 for English units orifice flow Q 0 67 A 2gy QR Page 14 GROUP INC WinStorm 3 0 User s Manual where 0 67 is the Orifice coefficient metric and English flow rate cfs weir perimeter ft allowed ponded depth on grate ft clear opening grate area available for flow ft acceleration due to gravity ft s n gt lt VC l Area or perimeter reduction to account for clogging is not included The designer should consider the factor when input area and perimeter WinStorm selects the minimum of weir or orifice flow for the given ponded depth as the controlling discharge The capacity of a grated inlet in a sag is based on the minimum flow calculated from weir and orifice conditions The figure below demonstrates the relationship between weir and orifice flow If Qo is greater than Qw to the left of the intersection in the figure then the capacity would be that calculated with the weir equation If however Qo is less than Qw to the right of the intersection then the capacity as determined with the orifice equation
3. 12 The applicable equations are as follows The length of curb inlet required for total interception using equation 1 0 6 L 0 60 oe 5 gs n Se where Coefficient 0 6 for English and 0 817 for metric L length of curb inlet required ft Q flowrate in gutter cfs S longitudinal slope ft ft n Manning s roughness coefficient Se equivalent cross slope ft ft for non depressed inlets The equivalent cross slope Se for a depressed curb opening inlet using equation S S E W where Se equivalent cross slope ft ft Sx cross slope of the road ft ft a gutter depression depth ft W gutter depression width ft E ratio of depression flow to total flow The ratio of depression flow to total flow is determined using the following equation 8 3 Ww K B 1 1 w T Kw Ko The simplified HEC 12 equation using W T is not used in lieu of the more general conveyance form of the equation THOMPSON PROFESSIONAL GROUP INC Page 9 WinStorm 3 0 User s Manual where is ratio of depression flow to total flow Kw conveyance of the depressed gutter section ft s K conveyance of the gutter section beyond the depression ft s Conveyance is calculated with equation 5 3 A K n P23 where conveyance of cross section cfs area of cross section E x 1 486 for English Manning s roughness coefficient wetted perimeter ft DE pW Inlet interception capac
4. De aen fo 33 M Runoff Coefficients For Land Use Type Storm Frequency Depression Width fis ft eee T Standard Curb Size Increment E ft Standard Slotted Drain Increm fi o m Allowable Bypass G 0 25 cts Maximum Ponded width 12 ft Multi Family Maximum Ponded Depth fos ft Single Family Analysis Commercial Industrial Develop Inlet in Sag Opening Height fo s ft Grass Undeveloped 9 35 Minimum Tc fi 0 min Transverse Gutter Slope 0 02 ftft Drainage Area ID Prefix a None Gutter n Value fo oi Minimum Cover Depth 25 ft F Junction Loss Computation It is recommended that Project Preferences and Project Information be entered first because data is automatically stored and used for the other inputs English Units Only one unit may be selected by activating the toggle of Metric Units the desired units Once selected the option is utilized to display the associated standard units within each dialog box Storm frequency Storm frequency must be indicated by selecting the Design Analysis appropriate toggle button At least one option is required If both Design and Analysis frequencies are used then Design is always the first event computed by the system Default Values The system is using a list of defaulted values depending Metric English units on measurement units These values must be set up at the beginning of the project If the values are changed f
5. Transportation STORM DRAIN DESIGN Last Update Jan 25 2002 Notice The results derived from the Texas Hydraulic System WinStorm are intended for the review interpretation and approval by a Registered Professional Engineer The program has been tested however the developers assume no responsibility for the validity of the input data and results produced by WinStorm program Runoff Coefficients For Land Use Type Analysis Menu Bar The menu bar consists of six options Project Run Print Reports Convert Help and About Project Options New This option creates a new WinStorm File Prior to opening the new file WinStorm will close the original file If any changes were previously made to the original file and not saved a dialog appears prompting to save or ignore the changes BABE Page 26 GROUP INC WinStorm 3 0 Open Save Save As Exit Run Options Run Project Compute Runoff Compute Inlets Print Reports Options Convert Option Help About User s Manual This accesses an existing WinStorm project file If another project is already open WinStorm will close the original project If any changes were previously made to the original file and not saved then a dialog appears prompting to save or ignore the changes This operation saves the current contents to the currently active WinStorm project Any changes made on the dialog are not recorded in the WinStorm project fil
6. Wet Time when hydrograph starts It is the time interval in which the hydrographs are generated in fraction of hour The rainfall depth for the project area The number can be computed using the county name and the frequency G Besa PR Page 34 GROUP INC WinStorm 3 0 User s Manual Base flow A constant flow from which the hydrograph starts SCS Rainfall distribution Rainfall distribution based on location of watershed For Table Texas two types of rainfall distribution are considered Type IL and Type III Node List When you select the Add Node or Edit Node icon from the Node List area of the Drainage Components tab the dialog box below appears The Edit Node function can also be accomplished by double clicking on the desired row Pt Node Data Input Form Node Select Drainage Area Node ID v Description Critical or Top 845 67 ft Default Elev Elevation Soffit or Flowline Node Inlet Type Curb On Grade Curb On Grade Curb In Sag 842 Grate On Grade Grate In Sag Curb And Grate On Grade Junction Loss Calculati Curb And Grate In Sag i A Slotted Drain Junction Type User Ke Vel Head x Circular Manhole Curb On Grade Curb Length fi 5 ft Gutter Depression 0 25 ft Depression Width 1 5 ft Cancel Node ID Any alphanumeric characters maximum 8 The ID should be selected from the drainage area list to have connect
7. analyzing various conveyance elements links including pipes box culverts arch pipes elliptical pipes semicircular arches and ditches e Optionally junction loss computations can be performed at the nodes e Graphical visualization of the hydraulic grade line for a selected reach e Runoff computations using SCS TR20 method or the Rational method are provided for e WinStorm is capable of designing and analyzing a system simultaneously when sizes of features are specified Additionally two frequency storms can be run simultaneously in order to evaluate the performance of a system during different events or design a system based on one event and analyze the design under a different event Design Procedure The input and computation features within WinStorm are designed to follow the typical progression of urban storm drain design An understanding of this procedure is beneficial in developing the systems describing it within WinStorm and evaluating the results Storm drainage design is an iterative procedure Design modifications are made throughout the project development process to arrive at an economical and hydraulically suitable solution These modifications often require extensive recalculations of initial designs and it is this repetitive yet necessary step that the true benefits of WinStorm can be realized The following describes the typical design steps of both manual storm drainage design and the steps recommended for the inpu
8. field with a maximum of 32 characters Job Alphanumeric field with a maximum of 16 characters Description Alphanumeric field with a maximum of 64 characters Drm SSIONAL Page 29 GROUP INC WinStorm 3 0 Outlet ID County e b d values Absolute Intensity Input Tail water Compute Tail water No Tail water Out fall channel s Manning n value and slope Additional Q X Y table Browse SaveX Y Plot User s Manual Any alphanumeric maximum 8 characters A Texas county name to get e b d values for the intensity calculation Rainfall intensity coefficients based on county and frequency event This field can be filled by selecting a county name or key in the values These values and Tc are used to compute the rainfall intensity Intensity to be used in lieu of computed intensity Using combination of absolute and computed intensity may result in unexpected flow in conduits Selecting this option a dialog box with Design tailwater elevation and Analysis tailwater elevation shows up Selecting this option a panel containing required data to compute tailwater shows up The user may input the out fall channel cross section up to maximum 50 X Y points Manning n value for channel and slope are required The tailwater is computed based on the channel s uniform depth using the fall discharge A text shows up when this option selected Data required to compute tail water using uniform depth at
9. network layout THOMPSON PROFESSIONAL GROUP INC Page 4 WinStorm 3 0 User s Manual Special Considerations and Limitations e Pumps are not supported Other commonly utilized pump routines and other available programs should be utilized and the results integrated with WinStorm e Weirs and orifices must be modeled as equivalent length conduits or as losses applied to junctions manholes e Multiple incoming links to a node allowed but only one outgoing link e Only one outfall per network e Diversions and looped systems must be split up and modeled as separate networks Network Don ts Networks must be split up that violate basic computational engine rules Examples of these scenarios are illustrated below D THOMPSON PROFESSIONAL Page 5 GROUP INC WinStorm 3 0 User s Manual WinStorm Design Algorithms This section indicates the methods and equations used internally by WinStorm All of the equations are given in their English form All metric units are in meters except area and intensity which are given in hectares and millimeter per hour respectively Refer to the metric release of the Hydraulic Volume of the Design Manual for the metric version of these equations and FHWA Urban Drainage Design Manual Hydraulic Engineering Circular 22 Nov 1996 Runoff Calculation WinStorm models runoff using the Rational Method and the SCS TR 20 Method The Rational Method is expressed as where discharge c
10. outlet and proceeds upstream through each link in the same fashion A starting HGL at this downstream point elevation must be defined The procedure for developing the HGL through a link of the network from downstream node to upstream node is as follows Uniform Depth Critical Depth QA Page 20 GROUP INC WinStorm 3 0 User s Manual 1 Beginning with the HGL at the downstream node HGL the Energy Gradeline EGL is computed from y EGL HGL 28 where v velocity of flow ft s g gravity due to acceleration 32 2 ft sec HGL elevation of hydraulic gradeline Assuming a very small change in the energy and depth an increment termed Ay compute HGL from HGL HGL Ay The increment in length Ax corresponding to an assumed increment in depth of water surface profile is describe by the relation Ax HGL HGL So Ss where So Slope of the conduit pipe Sf Average friction slope for the two adjacent depths under consideration Sat Sp 2 Friction slope at depth 1 and 2 is computing using Manning s equation This procedure of computing HGL and the curve length along the pipe proceeds until one of two things occurs 1 If the total length of the calculated curve equals or exceeds the length of conduit then the HGL is the depth in the pipe at the entrance or 2 If the current depth of the water profile is equal or less than uniform depth then the HGL is the uniform dep
11. selected the dialog box dynamically changes to reflect the selection as depicted below Ei WinStorm Version 3 Project English Test Project Run PrintReports Convert Help About Computation TxDOT WinStorm STORM DRAIN DESIGN Version 3 0 4 10 24 00 12 PROJECT NAME English Test JOB NUMBER 2 PROJECT DESCRIPTION english job DESIGN FREQUENCY Years MEASUREMENT UNITS ENGLISH OUTPUT FOR DESIGN FREQUENCY of C Value Tc Used Intensity Supply Q acre min imin fin hr 10 Pavement Multi family 10 0 10 0 10 0 10 0 10 0 10 0 Compute Options Several computation options are supported within this tab To select the desired results simply click the Option Project Compute Runoff Inlets and Network Runoff Runoff computation only Inlets Runoff and Inlets computation only Plot HGL Plot Hydraulic Grade Line for a selected reach View Save Output View the computation text using Notepad windows and Save it QR Page 44 GROUP INC WinStorm 3 0 Plotting the HGL User s Manual When the Plot HGL button is selected another dialog box appears such that the desired reach may be defined WinStorm Version 3 Project D WinStorm30 English stm Project Run Print Reports Convert Help About Project Information Drainage Components Computation Options TxDOT WinStorm STORM DRAIN DESIGN Version 3 0 4 Project Define reach for HGL n 1 30 01 11 4 Runoff PROJECT NAME JO
12. the out fall channel This Q and the discharge from the drainage network are used for tailwater computation Channel cross section X Y coordinates up to a maximum 100 points This command button will open a dialog box to import an existing text file containing the X Y values The values must be stored in the file as X Y comma separator This command button will open a dialog box to save the X Y coordinates from table to a text file The values will be stored in the file as X Y comma separator This command will plot the X Y coordinates Q Res SSIONAL Page 30 GROUP INC WinStorm 3 0 User s Manual Drainage Components When the Drainage Components tab is selected the dialog dynamically changes to reflect the selection as depicted below kd WinStorm Yersion 3 Project EnglishT est Project Run Print Reports Convert Help About Drainagee Area List Node List Link List Des crip on Any Description Area 2 descript Add Edit Update Grate In Sag Grate In Sag Junction M anhole Grate In Sag Junction M anhole Grate In Sag Junction M anhole Grate In Sag Slotted Drain Curb On Grade Slotted Drain Slotted Drain Curb On Grade Slotted Drain List of drainage area included into project Node includes Junctions Manholes Inlets Any valid convey type pipe ditch For each drainage component list add edit and update buttons are available The same fun
13. would be used Weir Q lt h Orifice Qxh Inlet Capacity Q Orifice Control Effective Head h Combination Inlets Combination inlets consist of a curb opening inlet and a grate inlet placed side by side A combination inlet is sometimes used with a part of curb opening placed upstream of the grate and is called a sweeper inlet THOMPSON PROFESSIONAL GROUP INC Page 15 WinStorm 3 0 User s Manual The curb opening intercepts debris that might otherwise clog the grate inlet Combination inlets may be used under special conditions The experience and many studies indicate that the additional cost of such inlets is rarely justified due to the relatively small additional inlet capacity afforded The data are insufficient to allow a true GRATE CURB COHBINATION SECTION A A INLET capacity calculation For combination inlets WinStorm computes the capacity of grate inlet and curb inlet separately and select the greatest of two If the curb opening length is greater than grate length WinStorm computes the sweeper s capacity and selects the greater capacity of grate inlet plus sweeper or curb opening One of the advantages of combination inlets is that the curb inlet intercepts the debris and reduces the clogging factor for grate Slotted Drains gp mueson SSIONAL Page 16 GROUP INC WinStorm 3 0 User s Manual The following equation describes the slotted drain length required for tota
14. 1 e Conveyance elements or links e g pipes boxes or ditches are identified by a single numeric identification e g 1 765 3 and the respective upstream and downstream nodes are entered in exactly the same manner used to define the inlet junction or outfall e Shortcut methods of entering identifications are provided to assist in maintaining the consistency of the ID WinStorm 3 0 is case sensitive Two inlets named al and Al would not be considered the same identification therefore caution must be used in naming nodes e All dimensions are in feet for English units and meters for metric units Exceptions to this are drainage areas which is measured in acres English and hectares metric and intensity which is measured in inches per hour English and millimeter per hour metric Each input data has a label indicating the measurement units e All WinStorm project files are binary with stm extension e WinStorm project files created with an old version can be opened with version 3 0 A dialog box is prompted asking Yes No for the old stm file conversion QR Page 24 GROUP INC WinStorm 3 0 User s Manual Error Checking All input data windows contain an OK Update Add or Cancel button that performs data checking as each element is entered If the window is closed using the X or Cancel option then the data will not be checked It is recommended to select the OK or Update button in order to ensure data is corre
15. B NUMBER PlotHGL PROJECT DESCRI DESIGN FREQUEN MEASUREMENT UN OUTPU Plot HGL for 5 year frequency Plot HGL Reach HGL From node list Reach HGL to node list Set Flow Reach From To Plot HGL 10 0 Pavement Multi family 10 0 10 0 10 0 10 0 10 0 10 0 A list with all available node to create a reach A list with all available node to create a reach Define the reach based on list selection Define the path of flow Upstream node reach ID Downstream node reach ID Pressing the Plot HGL button dynamically changes the dialog as depicted below The complete path of the flow is shown on the top of the window Use X top right window button to hide the window QR Page 45 GROUP INC WinStorm 3 0 User s Manual HGL Path A1 42 43 44 45 A6 A7 A8 A9 01 convey Base line elevation 825 ft Print HGL Outfall flowline eley 829 5 Reach 1794 00 ft When the Print HGL button is selected printer dialog box appears The HGL plot can be printed if the computer is linked to a printer QR Page 46 GROUP INC
16. HOMPSON PROFESSIONAL Page 7 GROUP INC WinStorm 3 0 User s Manual WinStorm calculates the ponded depth and the ponded width by an iterative process using a modified Manning equation for spread flow conditions Q Ke ny Sx A S XT Te S where Q flow rate in gutter cfs n Manning s roughness coefficient Kg 0 56 English and 0 376 metric S transverse slope or cross slope ft ft So longitudinal slope ft ft T ponded width ft y ponded depth ft Ponded Width allowable distance water may accumulate into the roadway WinStorm reports a warning if gutter flow exceeds this ponding width measured from the curb face ft or m Ponded Depth allowable depth water may accumulate over a grate or curb at a sag inlet WinStorm uses this as the default depth to size grates and curbs at sag ft or m When there is a change to the measurement units the inlet control data must be updated accordingly otherwise the system is using the previous inlet control data stored into the database Inlet Calculations Curb Inlets On Grade Calculations The computation of on grade curb opening inlets involves a determination spread or ponded width characteristics computation of length required for total interception and consideration of inlet efficiency THOMPSON PROFESSIONAL GROUP INC Page 8 WinStorm 3 0 User s Manual Pavement The hydraulics of Curb Inlets On Grade is derived from HEC
17. P INC Page 40 WinStorm 3 0 User s Manual Slotted Drain Slotted Drain length The length of the slotted drain Carry Over or bypass Carry Over to Inlet The inlet ID to carry over the flow Allowable Q to Bypass The discharge to be carried over to other inlet Percent of Q The discharge to be carried over to other inlet computed as a percentage of the total flow at the inlet Link List When you select the Add Link or Edit Link icon from the Link List area of the Drainage Components tab the dialog box below appears The Edit Link function can also be accomplished by double clicking on the desired row QE Bow Page 41 GROUP INC WinStorm 3 0 User s Manual Pt Conveyance Input Form Run fi Node ID 4 Elevation From ft Soffit or Flowline 842 42 h Length jo ft E Compute Size Rise 2 5 Span 4 Number of Barrels Select Node To lisNode Downstream a2 842 13 ft Shape mm Run From Node ID To Node ID Select Node list Soffit or Flowline elevation upstrem Soffit or Flowline elevation downstream Length Shape list Material List Compute size option Max Rise Required Cancel Run number If null will be generated Upstream node ID Click the text box and select from the list Downstream node ID List with available node to create the network Soffit or flowline elevation at upstream node Soffit or flowline
18. WinStorm 3 0 User s Manual Introduction WinStorm 3 0 represents the newest release of the WinStorm program by TxDOT The program itself while having much of the same look and feel of previous versions has had its GUI Graphical User Interface and hydraulic engine redone to provide for more speed flexibility computational capability and robustness Also WinStorm 2 0 limitations regarding installation and data input have been eliminated New features in v3 0 include e Independent computation of runoffs and inlets without being incorporated into a drainage network e Allows for the creation of a network with all or only a partially selected number of nodes and links e Allows the computation of a system tailwater using normal depth as calculated within an input cross section of the outfall channel e Graphic representation of HGL computations e Includes the ability to use the SCS TR20 methodology for runoff computations for drainage areas not suitable for the rational method e Allows for the conversion of units of measure within an existing project e Carryover or bypass flow at an inlet can be defined by a specific discharge or as a percentage of incoming discharge e Utilization of standard Windows help files Credits for the development and testing of the program are represented below Principal Developer Michael Mihai Stan P E ISD Contributors David Stolpa P E Bridge Division Amy Ronnfeldt Bridge Division Ken Mu
19. and shape Under uniform flow depth and flow area are constant and the friction slope actual slope and energy slope are all equal After sizing a run WinStorm calculates the uniform flow depth the flow area and the velocity through the conduit The time of travel to the downstream node is computed by adding the longest travel time to the upstream node and the travel time through the conduit As the time of travel increases downstream the design rainfall intensity decreases It is possible that the cumulative value of CA does not increase in proportion to the inverse of the design rainfall intensity This is most likely when junctions introduce either no additional drainage area or just a small increase in CA The result can be a drop in the calculated discharge from upstream to downstream If this situation occurs WinStorm will use the higher discharge for design and analysis Similarly if the slope of a downstream run is higher than the preceding upstream run such that Manning s equation would indicate a smaller conduit size downstream when designing WinStorm will flag the downstream conduit size such that the user may adjust the size Hydraulic Grade Line Calculation The methodology employed by WinStorm to compute the water surface profiles though a storm drain network is typical of any open channel water surface procedure A backwater analysis is performed through the system beginning at the most downstream point outlet and progr
20. cal for the drainage area C value Run off coefficient for the overland part of the drainage area Slope Average water course Slope of the overland flow path Length The length of the flow path for the overland area Velocity Flow velocity for concentrated flow QR Page 33 GROUP INC WinStorm 3 0 Travel Time Total Tc User s Manual Travel time for the specific portion of the area Computed travel time Compute Runoff Using SCS TR20 Method When the SCS TR20 button is selected then the widow dialog box below appears i Runoff Using SCS TR20 Method Data required for SCS TR20 Method Drainage Area fi 22 sql Time of Concentration fo 33 hour Curve Numyer z2 E Antecedent Moist Condit 2 El Hydrograph Starting Time fo o houn Hydrograph Time Increm bi hour Rainfall Depth 265 n 2 Base flow foo efs SCS Rainfall Distribution Table Texas Type2 24 Hour x an o Peak Discharge 561 746 cfs Time to peak 2574 hour Drainage area Time of concentration Curve number Antecedent Moisture Condit Hydrograph start time Hydrograph time increment Rainfall depth LO x TR20 Hydrograph Qicfs o ho 4 6 8 Time hour Drainage area in square miles or square kilometer The average time of concentration in hour SCS curve number depending on soil characteristics and land use A number representing the moisture conditions 1 Dry 2 Medium and 3
21. ctions can be used by double clicking the line THOMPSON PROFESSIONAL GROUP INC Page 31 WinStorm 3 0 Drainage Area List User s Manual When selecting Add or Update a Drainage Area dialog box appears as depicted below The update function can be accomplished by highlighting and double clicking the desired row Ke Drainage Area Data Input Form Rational Method Drainage Area Data Drainage Area ID a2 Descriptionfaea2 000 sts sS Supplied Discharge fo cfs Absolute Intensity fo inch h Drainage Area C Runoff Coeff Compute Runoff fo 4 Ge fo li Using SCS TR20 Method p m Sub area Land Use Definition SCS TR20 Sub rea C Value Description 7 Pavement Compute Runoff 2 Concrete Using Regional 3 Industrial Regression Equations 4 Multi famil 5 Single family Reg Eq 6 Undeveloped Cancel Drainage Area ID An alphanumeric field with a maximum of 8 characters The field cannot be changed in the table Any changes are accomplished by using the drainage area data input form Description Alphanumeric field with a maximum of 32 characters Supplied discharge This is the user discharge This value will be used for Absolute intensity Drainage Area Runoff Coefficient Tc calculation This is the user intensity This value will be used to compute the runoff in the CIA equation Drainage area in acre or hectare Runoff coefficient depending on land use There are 6 land use types avai
22. ctly entered Whenever WinStorm determines an error in the input a message will be displayed in a message box specifying the type of error and the field in which the error exists A typical error message box is displayed below WinStorm Version 3 0 D wWinStorm30 english stm EA IN Invalid Drainage Area PESA Page 25 GROUP INC WinStorm 3 0 User s Manual Starting WinStorm WinStorm is typically run from the Windows Start button or from a shortcut saved to your desktop Once WinStorm is started the following screen appears on the desktop WinStorm Version 3 04 Jan 25 2002 Project File Untitled stm Project Run PrintReports Convert Help About Project Information Drainage Components Computation Units Default values Option For Pipe Elevation Connection English Metric English Default Yalues Match Soffit Match Flowline Standard Gutter Depression fo33 tt Storm Frequency Depression Width 1 5 ft Pavement 9 Standard Curb Size Increment E ft i Commercial 0 82 Standard Slotted Drain Increm fo m Allowable Bypass Q fo 25 cfs EI ice Maximum Ponded Width 1 2 M Multi Family Maximum Ponded Depth jos ft Single Family Inlet in Sag Opening Height fos ft Grass Undeveloped Minimum Tc fi 0 min Transverse Gutter Slope fo o2 fteft Drainage Area ID Prefix fa Gutter n Value fo o14 X Junction Loss Computation exas Department Win S tor m Yersion 3 04 2001 of
23. e conveyance of cross section cfs area of cross section ft Manning s roughness coefficient wetted perimeter ft DE gt The ratio of frontal flow intercepted to total frontal flow Ry 1 0 3 V V if V gt V R 1 0 if V lt V where Rs ratio of frontal flow intercepted to total frontal flow V approach velocity of flow in gutter ft s V gt minimum velocity that will cause splash over grate ft s The splash over velocity is of the form of V AL factor where Vo is splash over velocity A constant for different grate type N apower coefficient for different grate type L grate length factor 1 for English and 3048 for metric Grate Type Coefficient A Coefficient N Parallel 5 74872 0 5038679 Narrow 0 5058875 Curved Vane 0 5954068 45 Tilt Bar 0 5926234 30 Tilt Bar 0 7567052 Transverse 0 6454720 Reticuline 0 7659749 QES Page 13 GROUP INC WinStorm 3 0 User s Manual The ratio of side flow intercepted to total side flow 1 T i 0 083 oa s 23 L where 0 083 for metric and 0 15 for English units Rs ratio of side flow intercepted to total flow z inverse of transverse slope V approach velocity of flow in gutter A s L length of grate ft The efficiency of grate Es using the equation E R E R 1 E The interception capacity of the grate Qi using the equation Q E Q Q R E R 1 E The bypass flow rate or carryover is CO
24. e unless a File gt Save or File gt Save As operation is executed Hence any power interruption or malfunction will result in loss of data that can be avoided through the judicious use of the File gt Save tool Utilize this option to save the current settings to a new file name Utilize this option to close and exit the WinStorm application If the current project has not been saved a message is displayed Storm Drain Design Anal Project Print Reports C Run Project Compute Runoff Compute Inlets This option performs a complete WinStorm project computation including Runoff Inlets and Network Utilize this option to compute runoff only Utilize this option to compute inlets only Not Currently Available This option will convert the project measurement unit from English to Metric and vice versa Opens the WinStorm help file Gives information on the Version of WinStorm THOMPSON PROFESSIONAL GROUP INC Page 27 WinStorm 3 0 User s Manual Preferences When the Preferences tab is selected the dialog dynamically changes to reflect the selection as depicted below WinStorm Version 3 05 Jan 25 2002 Project File Untitled stm Project Run Print Reports Convert Help About Preferences Project Information Drainage Components Computation Units Default values Option For Pipe Elevation Connection Engish Metric English Default Yalues Match Soffit O Match Flowline Sereal En
25. elevation at downstream node The length of the conveyance link List with available conveyance shape 6699 List with available material list or Manning n value Option to compute the conveyance size Maximum rise required when compute size option THOMPSON PROFESSIONAL GROUP INC Page 42 WinStorm 3 0 Nuber of barrels Type Span Rise Left right side slope Bottom Width Ditch Depth Bottom Width User s Manual selected Number of barrels Default 1 Options include Box Circular PipeArch Arch Ellipse and Ditch The desired option is selected from the shape list The span of the selected shape For ditch span it is the bottom of the ditch The rise or the selected shape or the diameter of circular shape pipe Left Side Slope fo Right Side Slope fo ft ft Max Depth fo ft Side slope horizontal value horizontal vertical for ditches Options include Box Circular PipeArch Arch Ellipse and Ditch The desired option is selected from the shape list The depth of ditch is the rise Span is the ditch bottom For ditches the soffit elevation is the water surface in the ditch When designing ditches run once to compute the water depth rise in the ditch then adjust the soffit elevation such that the flow line matches the control elevation usually the ground QR Page 43 GROUP INC WinStorm 3 0 User s Manual Computation When the Computation tab is
26. essing upstream to the most remote nodes WinStorm will compute the hydraulic grade line using gradually varied flow analysis in free surface flow conditions and pressure flow computations under full flow conditions The resulting hydraulic grade line represents the locus of elevations to which the water would rise if open to atmospheric pressure e g piezometer tubes along a pipe run and can be used to evaluate the adequacy of the design and identify areas where flooding occurs PESA Page 19 GROUP INC WinStorm 3 0 User s Manual Hydraulic water Level Grade Line Piezometers The difference in elevation of the water surface in successive pipes usually represents the friction loss in conduits If the conduit has a slope equal to the friction slope then the HGL would be parallel to the top of the conduit If the conduit is placed on a slope less than friction slope then the HGL gradient would be steeper than conduit slope If the HGL rises above the top of the conduit soffit this would mean that the conduit is under pressure until at some point upstream the HGL is once again at or below the soffit elevation An analysis is usually necessary to determine the flow characteristics of the outfall channel The tailwater level occurring in the outfall to the storm drain system will be used in the development of a hydraulic grade line Hydraulic Gradeline The hydraulic gradeline HGL procedure begins at the most downstream node
27. fs runoff coefficient cfs hr ac in rainfall intensity in hr drainage area acre Q C I A The rainfall intensity is a function of frequency geography climatology and the specific time of concentration for the watershed The time of concentration describes the longest time it takes for runoff from the most remote part of the watershed to travel to the outfall of the watershed TxDOT uses the following equation for rainfall intensity b le t d where I rainfall intensity in hr te time of concentration min b d e empirical factors that characterize the intensity duration frequency IDF curves for Texas counties The SCS TR 20 Method is intended for larger contributing drainage areas generally greater than 200 acres The basis for computing direct runoff in TR 20 is the equation _ P 2S Q P 8S D THOMPSON PROFESSIONAL Page 6 GROUP INC WinStorm 3 0 User s Manual where actual runoff inches potential maximum retention inches rainfall inches mn Hou ou The potential maximum retention P may be expressed as 1 2S As such Q 0 if P is less than or equal to 2S The value of S is more directly related to the SCS runoff curve number 5 10001 CN where CN SCS curve number Determination of the SCS curve number is based upon land use soil type and other parameters Most readily available hydrologic reference books have tabulations of various CN values Another factor incl
28. ity is then defined by Qin ercepted Qrotal x Efficiency where Qi intercepted discharge cfs Qt total inlet discharge cfs Efficiency inlet efficiency defined below fo ee dee Lis Efficiency 1 7 1 L where L length of curb inlet required for 100 interception ft L length of curb inlet provided ft Curb Inlets in a Sag A curb inlet operates as a weir to depths equal to the curb opening height and as an orifice at depths greater than 1 4 times the opening height At depths between 1 0 and 1 4 BAB Page 10 GROUP INC WinStorm 3 0 User s Manual times the opening height flow is in a transition stage and should be based on the lesser of the weir and orifice capacity computed The following equation describes the inlet length required for a curb inlet in a sag operating as a weir pee 1S Cwh WinStorm reports the capacity by rearranging the previous equation Q C L 1 8 W h where length of curb inlet opening ft total flow reaching inlet cfs weir coefficient 3 087 English and 1 25 metric head at inlet opening allowed ponded depth at inlet not computed lateral width of depression 27 90 Holl The equation for capacity of curb openings operating under orifice conditions is the following Q CodoL 2gh where Q total flow reaching the inlet cfs C orifice coefficient 0 67 d depth of curb opening This is the physical depth of the opening including depressio
29. ivity Select Drainage Area List of the drainage area ID available for connectivity Description Any maximum 32 characters Critical or Top Elevation The elevation to flag when the HGL in the node is above this value usually the lip of gutter elevation Top Elev QR SSIONAL Page 35 GROUP INC WinStorm 3 0 User s Manual Default Soffit or Flowline The elevation to connect the pipes in the node Default is Elevation soffit elevation Node Type List List with all available node type Additional Discharge Additional discharge in the node from outside the system Junction Loss Calculation Junction Loss Calculation Junction Type RURA Cais He fo 1 1 None User Ke Vel Head User Ke Delta VellHead fde Vel Head Ke Vel Head b Length 5 Bend Type Narrow Absolute Loss Junction Type A list of various junction loss calculations is depicted Ke Value This field is used for the Ke value bend angle or Absolute loss Approach Gutter on Grade Approach Gutter on Grade N gutter value fo 5 Longitudinal Gutter Slope 0 006 ftft Transverse Gutter Slope 0 0208 ftt Transverse Gutter Width 1 5 ft Max Allowed Ponded Width 12 ft Composite Cross Section Data Transverse Slope2 fo ft Transverse Width2 0 ft 6699 N gutter value Manning n value for the gutter Longitudinal gutter slope The slope along the roadway Transverse gutter slope The cross slope of the gutter
30. l interception of the flow weir flow equation i E 0 706 0 aia SE 749 r 0 384 n where 0 706 for English and 1 04 for metric units L length of drain required for total interception of flow ft Q flowrate in gutter cfs S gutter longitudinal slope ft ft E an exponent of the longitudinal slope S E is a function of S and z as shown z reciprocal of transverse slope ft ft n concrete gutter roughness coefficient usually about 0 015 The equation for slotted drain is limited to the following ranges of pertinent variables e total discharge lt 5 5 cfs e longitudinal gutter slope lt 0 09 e roughness coefficient n in the curb and gutter 0 011 lt n lt 0 017 The longitudinal slope exponent E is determined with the equation E 0 207 19 0845 2 6138 0 0001z 0 007z 0 049Sz WinStorm calculates carryover for slotted drain as follows L 1 769 0 918 1 Q osisofi r where Q carryover cfs Q total gutter flow rate cfs L design length of slotted drain inlet ft L length of slotted drain inlet required to intercept the total flow ft Note Regarding carryover or bypass flow for any type of inlet on grade that allowed a carryover flow or bypass the approach flow to design the inlet is reduced with the amount of carryover D THOMPSON PROFESSIONAL Page 17 GROUP INC WinStorm 3 0 User s Manual Conveyance Computation Sizing Conveyance Ele
31. lable Time of concentration to compute rainfall intensity QB Page 32 GROUP INC WinStorm 3 0 User s Manual Sub area Land Use There are 6 land use types are available with the Definition corresponding C value SCS TR20 This command will open a Windows for runoff computation using SCS TR20 method Regression Equations This option is not available Compute Tc If the Compute Tc button is selected then the dialog widow below appears ia Compute Time of Concentration Tc Land Use Flow Regime C Yalue Slope Length VYelocity Travel Time ftft ft fts min Forest with Heavy Ground Litter Overand po ooo ooo oor Fallow or Minimum Tillage Oveand oo ooo ooo oor Woodland Ovelnd oo ooo ooo oor Short Grass pasture Oveand oo ooo ooo oor Cultivated Straight Row Oveand oo ooo ooo oor Nearly Bare Land and Untiled Overland oo ooo ooo oor Grassed waterway Overland Sheest 00 ooo ooo oor Pavedarea SheetFlow ooo ooo ooo oor Small Upland Gulies SheetFew 00 ow 000 om ooo 000 NOTE Overland flow time is computed using gase 0 00 equation Tc K 1 1 C L 0 5 Slope 0 333 K 0 702 metric K 0 3875 english For Channelized Flow Use Length and Velocity After the user enters the C Value Slope and Length click on the Travel Time column to calculate Tc Land Use The type of land used in the drainage area Flow regime Type of flow typi
32. llin P E Bridge Division Stewart Molina P E Bridge Division Jim Thompson P E Thompson Professional Group Houston TX Review Houston District Austin District Fort Worth District amp Dallas District Jim Thompson P E Thompson Professional Group Houston TX Support Judy Skeen P E ISD Mary Lou Ralls P E Bridge Division Leah Coffman P E ISD D THOMPSON PROFESSIONAL Page 1 GROUP INC WinStorm 3 0 User s Manual This Seminar document has been prepared using much of the information and exhibits provided within the Help files of WinStorm 3 0 Acknowledgement is hereby given to the above individuals for their contribution in these regards Editing and additional information regarding the various computational procedures has been added for further explanation by James F Thompson P E of Thompson Professional Group Inc D THOMPSON PROFESSIONAL Page 2 GROUP INC WinStorm 3 0 User s Manual Overview WinStorm models storm drainage systems using a drainage network comprised of three basic drainage components 1 Drainage Areas 2 Nodes 3 Links The user describes the components of the system by proceeding through a series of dialogue windows defining each portion of the drainage components The computational features within WinStorm include the following e Computing peak discharges associated with the drainage areas e Designing and or analyzing 7 types of storm drain inlets e Designing and or
33. ments pipe ditches WinStorm will either analyze the hydraulics of a described conduit or channel or size the run according to the specified maximum size and type of element The design discharge for each run is based on the contributing drainage area the composite runoff coefficient and the longest travel time to the upstream node of the run Numerous algorithms are employed to perform the pipe and ditch hydraulic computations The fundamental equations and terminology are presented here for reference purposes The most widely used formula for determining the hydraulic characteristics of storm drain networks is the Manning Formula expressed by the following equation val R23 g2 n where mean rate of flow ft s the hydraulic radius ft the slope of hydraulic gradeline ft ft Manning s roughness coefficient pnw lt The hydraulic radius R is defined as follows A P R where Wp A wetted perimeter ft cross sectional area of flow A To satisfy continuity Q AV where Q discharge m s Combining these equations gives the following equation Q 1 A R23 gl n QES Page 18 GROUP INC WinStorm 3 0 User s Manual Conveyance describes the geometric carrying capacity of a hydraulic conduit and is described by the following equation Friction Slope is that slope S in Manning s formula required to convey a specified discharge under uniform flow conditions given a depth roughness
34. n Width The width of depression in front of opening Usually it is the lip of gutter Max Allowed Ponded The maximum allowed ponded depth for inlet calculation Depth Inlet Opening Height The inlet opening height including the depression Grate on Grade Pa Grate Type List of grate type available Grate Width The grate width P rea Page 38 GROUP INC WinStorm 3 0 Grate length Grate in Sag User s Manual The grate length Grate In Sag Grate Type Parallel Effective Grate Area fa sf Effec Grate Perimeter 46 ft Max Ponded Depth fo 5 ft hy Safety Reduction Factor jo Es a Grate Type Grate Area Grate Perimeter Maximum Ponded Depth Safety Reduction Factor er Ger hamse OK List of grate type available The effective grate area Bar sizes should not be included The effective grate perimeter Bar sizes should not be included The perimeter should be computed for 3 side or 4 side depending on the grate location The maximum allowed ponded depth for inlet calculation The inlet capacity will be reduced with this percent Curb and Grate on Grade combination inlet Curb And Grate On Grade Grate Type X Grate Width o o ft Grate Length o o ft Curb Lenath jis ft Gutter Depression 0 25 ft Depression Width fi 5 M Grate Type Grate Width List of grate type available The effective grate width Bar sizes sh
35. n depth L length of curb opening inlet ft g acceleration due to gravity ft s h effective head at the center of the orifice throat Allowed ponded depth 0 5d The depth of opening do will vary with the type of inlet used The user must input the allowed ponded depth as design criteria for curb inlet in sag calculations QR Page 11 GROUP INC WinStorm 3 0 User s Manual Grate Inlets on Grade The capacity of a grate inlet on grade depends on its geometry and the cross slope longitudinal slope total gutter flow depth of flow and pavement roughness The design of a grate inlet on grade involves an analysis of given grate dimensions to estimate the interception rate The difference between the estimated interception rate and the total approach discharge equals the bypass rate The following procedure is applicable to grate inlets on grade The ratio of discharge over the grate Frontal Flow to flow to total flow is determined using the following equation x 8 3 E Kw B 1 1 a T Ky Ko The simplified HEC 12 equation using W T is not used in lieu of the more general conveyance form of the equation where Eo ratio of flow over the grate to total flow Ky conveyance of the area over the grate ft s Ko conveyance of the pavement section beyond the grate cfs Conveyance is calculated with the following equation AY K n P23 QR Page 12 GROUP INC WinStorm 3 0 User s Manual wher
36. or an BAB Page 28 GROUP INC WinStorm 3 0 User s Manual existing project then only the new drainage components are using the new input Option for pipes Soffit elevation option default or Flowline is available to elevation connection connect the links at nodes Default Runoff Defaulted values for runoff coefficients Maximum 6 land Coefficients use type Junction Loss Option to perform junction loss computation at each computation upstream node Several computation options are available Prefix for ID Option for the prefix for Drainage area ID Maximum 4 characters Project Information When the Project Information tab is selected the dialog dynamically changes to reflect the selection as depicted below WinStorm Yersion 3 04 July 2001 Project File D WinStorm30 Houston stm Project Run Print Reports Convert Help About Project Information Drainage Components Computation Project Name Test Job 7 Compute Uniform Depth Using The Outlet Channel oe Cross Section tailwater is the uniform depth Description we are gonna learn this today maybe 110 County List Outlet 1D 01 Hanis 7 w Runoff Intensity Coeff 100 Tailwater Elevation Options e value 0 753 95 rant ror value OT d value 77 0 Absolute Intensity El Browse fo inch h Manning s n 0 033 Channel Slope 0 001 2 ftt Additional Q e50 cts i SavexY Project Name Alphanumeric
37. ould not be included D THOMPSON PROFESSIONAL GROUP INC Page 39 WinStorm 3 0 Grate length Curb Length Gutter Depression Depression Width User s Manual The effective grate length Bar sizes should not be included The length of the curb inlet Gutter depression The a value from 0 to 6 inches The width of depression in front of opening Usually it is the lip of gutter Curb and Grate in Sag combination inlet Curb And Grate In Sag ote Grate Type Parallel bi Effective Grate Area 2 sf Effec Grate Perimeter 3 6 ft Max Ponded Depth 0 5 ft Curb Lenath 5 ft Gutter Depression Width fi 5 ft Max Ponded Depth fi Mt Inlet Opening Height fo 5 ft Grate Type Grate Area Grate Perimeter Maximum Ponded Depth Curb Length Gutter depression Width Maximum Allowed Ponded Depth Inlet Opening Height List of grate type available The effective grate area Bar sizes should not be included The effective grate perimeter Bar sizes should not be included The perimeter should be computed for 3 side or 4 side depending on the grate location The maximum allowed ponded depth for inlet calculation The length of the curb inlet The width of depression in front of opening Usually it is the lip of gutter The maximum allowed ponded depth for inlet calculation The inlet opening height including the depression THOMPSON PROFESSIONAL GROU
38. sses 3 Absolute junction losses Manhole Junction Loss V 2 H K 28g where V Velocity at the upstream node of conveyance K Loss Coefficient for manhole junction For manhole losses please reffer to Modern Sewer Design Bend Losses Bend losses may be estimated from the equation TR b b 2g Where K can be estimated from the following table Degree of Turn at Bend I 0 5 0 56 60 0 64 75 QB Page 22 GROUP INC WinStorm 3 0 User s Manual gomso SSIONAL Page 23 GROUP INC WinStorm 3 0 User s Manual Input amp Computation Naming Conventions and Input Rules There are a few rules and conventions that apply to identifications of various system components Below are some basic fundamentals that apply to WinStorm input e Input Fields or controls labeled with blue text are optional entries All other input fields and controls are either required or recommended e g for documentation e Drainage areas and Nodes should have an identification containing a maximum 8 alphanumeric characters e Project names are limited to 32 characters and Job names to 16 characters e Project descriptions are limited to 64 characters Other descriptions are limited to 32 characters e A drainage area and the respective node to which the discharge is to be applied must have the same identification in order to establish connectivity For example drainage area A 1 flow will enter through inlet A
39. t of the system into WinStorm 1 Locate tentative surface collection features e g inlets 2 Determine contributing drainage areas and define relevant runoff parameters 3 Compute runoff associated with each drainage area D THOMPSON PROFESSIONAL Page 3 GROUP INC WinStorm 3 0 User s Manual 4 5 6 7 8 Locate and size analyze each inlet for interception capacity and ponding criteria Locate and size analyze the capacity and hydraulics of each conveyance element pipe or channel Calculate the hydraulic grade line through the storm drain system Evaluate the suitability of the resulting system Revise the components as necessary to meet defined design criteria System Description The storm drain system must be described sufficiently to perform the requested analysis Data verification is provided throughout the program but a layout or description of the system is difficult to ascertain A storm drain system is a series of ditches inlets and enclosed conduits that are connected to collect runoff from drainage area to an outfall It can be represented by a network of nodes inlets and junctions interconnected with links or runs conduits terminating at a single point outfall It is this connectivity that must be defined by the user Certain identification protocols have been established to simplify the definition of the storm drain network and define the interconnectivity of the system Below is a simple
40. th at the entrance The resulting upstream HGL is subsequently used on the next upstream pipe as its starting downstream HGL If junction losses are desired then they are computed prior to progressing upstream and added to the hydraulic grade line Special Considerations If the starting HGL is less than critical depth or uniform depth then minimum of critical or uniform depth will be assumed If the HGL converges to equal the uniform depth the computations proceed to the upstream end at uniform depth QR Page 21 GROUP INC WinStorm 3 0 User s Manual e Once the HGL reaches the soffit of the pipe full flow conditions begin e Hydraulically steep pipes where uniform depth is less than the critical depth are checked with a backwater profile to verify if the resulting upstream HGL drowns out critical depth at the upstream end If it does then the backwater profile is accepted If the backwater curve does not exceed the critical depth then a forewater profile is generated for this supercritical condition A forewater profile uses the same procedure as above but progresses from the upstream end towards the downstream end It begins at critical depth at the upstream end and converges towards uniform depth as the calculations proceed downstream e The energy grade line computation is not included in WinStorm Junction Loss Calculation Three junction loss methodologies are discussed 1 Manhole junction losses 2 Bend lo
41. uded in the SCS TR 20 Method includes antecedent moisture content AMC which is a representative value of relative soil moisture valued as 1 for dry 2 for average and 3 for wet conditions The recommended value is 2 If an AMC value of 1 or 3 is chosen then the CN value is modified accordingly For AMC 1 CN 4 2CN 10 0 058CN For AMC 3 CN 23CN 10 0 13CN WinStorm will provide the value of P or rainfall depth in inches for 24 hour storms from NWS TP 40 relating to the County and storm event previously selected Six storm frequencies are supported Alternately a value of P may be input by the user directly The manner in which the storm is distributed is based upon various SCS distribution tables Again the user may use many different distributions however in Texas for 24 hour storms it is common to use a Type II or III 24 hour distribution It is recommended that NRCS formerly the SCS reference material be obtained to determine what distribution is appropriate for each County From these data WinStorm produces a runoff hydrograph using the TR 20 methodology and a peak discharge is provided in conjunction with the time to peak Gutter Flow Calculations There are two important considerations regarding the gutter approach flow the ponded width how far the water extends into the street and the ponded depth the depth of water in the gutter The ponded depth affects the interception rate of on grade inlets D T
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