Home

WWHM3 User Manual - Riverside County Flood Control

1. End Date Mixed Surface Types Calculate the composite Runoff Coefficient C for the BMP Tributary Area Use the following equation based on the WEF ASCE Method C 0 85812 0 7812 0 7741 0 04 C 0 00 Determine Design Storage Volume Vgyp Calculate Vy the 85 Unit Storage Volume Vy 2 Dgs x C V 0 00 infac ac 6 4 2013 14 08 PM All Datasets Stage Precip Evap POC1 Riverside County and local municipalities use the Rational Method Q C I A to calculate the LID BMP design volume Vgyp and flow rate Qpmp These calculations are completely separate from the other runoff calculations produced by SMRHM using HSPF See Riverside County s Design Handbook for Low Impact Development Best Management Practices September 2011 for the most up to date information regarding BMP standards The handbook should be consulted prior to the start of any SMRHM LID BMP modeling The calculation of the BMP design volume Vgyp and flow rate Ogyp is done on this screen The user first enters the 85 percentile 24 hour rainfall depth Dgs 98 Santa Margarita Region Hydrology Model Guidance June 2013 Eje Edit Wew Hep Summary Report D n XH m 2 e Eu usummess5aHuoosc depo reco z o Saves SBT PM The 85 percentile 24 hour rainfall depth Dg5 can be found for any location in the Santa Margarita Region from the Isohyetal Map button on the SMRHM map scr
2. po Roof Area po Ponies 0 Deselect Zero Select By GO lt 6 4 2013 12 56 PM The Project screen also contains the Schematic Editor The Schematic Editor is the grid to the right of the elements This grid is where each element is placed and linked together The grid using the scroll bars on the left and bottom expands as large as needed to contain all of the elements for the project A maximum of 500 elements is allowed NOTE All movement of water on the grid must be from the top of the grid down The space to the right of the grid will contain the appropriate element information To select and place an element on the grid first left click on the specific element in the Elements menu and then drag the element to the selected grid square The selected element will appear in the grid square The entire grid can be moved up down left or right using the Move Elements arrow buttons The grid coordinates from one project can be saved Save x y and used for new projects Load x y 39 LAND USE BASIN ELEMENT SMRHM Eje dt bew Hei ummary Report CLE Il Schematic i el Jedi ai ases a Ux I zuje ye FL santa Margarita Region Hydrology Model Guidance June 2013 p oHumHOG6 s5HUHBioc i mfx si DMA 1 Pr edeveloped DMA Name D Sulace Flows To Area in Drainage Management Areo Available Impervious Acres ajr fiesti p 3
3. 15 poo Qoo pot po 850 150 pto 16 poo poo poi poo 350 150 pio z o poo poo poi poo ps5o pao pol 18 poo Qoo pot po ps5o p3ao Qo 19 po poo poi poo ps5o pao pol 20 ooo poo poi poo ps5o pao pol 21 poo Qoo pot poo ps5o 30 pot 22 poo po poi poo ps5o pao pol 23 poo poo poi poo ps5o pao pol 24 00 poo pot po ps5o p3ao Pot 25 poo poo poi poo ps5o pao pol 26 poo poo poi poo ps5o pao pol 27 poo Qoo pot po ps5o 30 pot 28 n poo poo poi poo ps5o pao pol 29 poo poo Pot poo 850 150 pto 80 1 1 po poo poi poo 850 150 pio 31 po poo poi poo 850 150 p10 32 poo poo poi poo 850 150 pio 33 poo poo pot poo ps5o pao Pot 34 poo poo poi poo ps5o pao pol 385 poo poo pot po ps5o 30 Pot 36 1 poo poo poi poo ps5o pao pol 37 poo poo poi poo ps5o pao pol 388 poo poo poi poo ps5o pao pol 39 Doo poo poi po ps5o pao Qo 40 poo poo poi poo ps5o pao pol 41 poo Qoo pot po ps5o p3o pot 42 poo po poi poo ps5o pao pol 43 poo poo wot po X ps5o p3o pot 44 poo po poi poo ps5o pao pol 45 poo poo pot poo B50 L7 pto 149 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 46 0 00 0 00 0 01 0 00 3 50 1 70 0 10 CEPS Initial interception storage
4. 45 Santa Margarita Region Hydrology Model Guidance June 2013 The user has the option to specify that different outlets be directed to different downstream destinations although usually all of the outlets go to a single downstream location Auto Pond will automatically size a trapezoidal pond to meet the required flow duration criteria NOTE Auto Pond is available only in the Mitigated scenario Quick Pond can be used to instantly add pond dimensions and an outlet configuration without checking the pond for compliancy with flow duration criteria Quick Pond is sometimes used to quickly create a scenario and check the model linkages prior to sizing the pond Multiple clicks on the Quick Pond button incrementally increase the pond size The user can change the default name Trapezoidal Pond 1 to another more appropriate name if desired Precipitation and evaporation must be applied to the pond unless the pond is covered The pond bottom elevation can be set to an elevation other than zero if the user wants to use actual elevations All pond stage values are relative to the bottom elevation Negative bottom elevations are not allowed The pond effective depth 1s the pond height including freeboard above the pond bottom It is not the actual elevation of the top of the pond Pond sideslopes are in terms of horizontal distance over vertical A standard 3 1 H V sideslope would be given a value of 3 A vertical sideslope has a va
5. peo beo bro prs prs Qs or prs brs pes pe 2 peo peo P60 p70 P 75 0 75 75 75 075 pr75 pe5 peo 3 peo peo peo P 70 075 p75 0 75 075 75 075 p65 peo 4 pe peo peo pro poro pre prs 075 pre p75 pes 060 5 050 Qo5o ps5o Q e0 pe5 0 65 0 65 0 65 065 p65 p55 p50 6 1 1 p 50 p50 X p 50 p6o_ pes 0 65 0 65 0 65 0 65 0 65 0 55 0 50 7 50 X50 X050 Q0 X Q e5 065 0 65 0 65 0 65 0 65 0 55 0 50 8 11 p 50 fPp s5o X p 50 X Q0 pes 0 65 0 65 0 65 0 65 0 65 0 55 0 50 9 1 p40 pQ40 040 Q45 050 055 0 55 0 55 0 55 055 45 p40 13 p50 p50o p50 Q e0 065 0 65 0 65 0 65 065 0 65 0 55 50 14 50 fPps5o 050 P 60 P 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 15 1 1 p 50 X 0 50 X p 50 X peo P 65 0 65 0 65 0 65 0 65 0 65 0 55 p os 16 1 050 0 50 X O50 X Q e0 P 65 P 65 P 65 p65s SSS 050 7 eo peo ne pro prs br prs ors prs brs bes ps 18 p6so X peo p6o_ p70 P 75 075 75 75 75 75 Qe5 060 19 peo peo peo p70 075 075 0 75 075 075 075 65 peo 20 peo peo X peo p70 75 075 p75 75 075 75 X Qe5 60 21 50 0 50 X 0 50 X Q0 P 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 22 0 50 P5o X 0 50 X Q0 P 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 23 ps0 p50 p50 p60 0 65 0 65 p65 0 65 65 0 65 0 55 p50 24 50 0 50 050 P 60 pes 0 65 0 65 0 65 0 6
6. 1 The infiltration rate of the permeable pavement is greater than the peak rainfall rate 2 The infiltration rate of the permeable pavement is greater than the underlying native soil 3 There is subgrade layer of crushed rock gravel between the permeable pavement and the native soil 125 Santa Margarita Region Hydrology Model Guidance June 2013 Santa Margarita Region Hydrology Model Eje Edit View Zoom Help Del DA ASHE Os 6 ae G CAS MM Schemati E led S Permeable Pavement 1 Mitigated x Facility Name de nec Miligated Downstream Connection TM Facility Type Facility Dimension Diagram Facility Dimensions Overflow Data Porement Length It no ao P t Bottom Width M foo Ponding Depth Above Pavement It foo Elfective Total Depth 1 Bottom slope fU poo 1 Elfectree Volume Factor Layers for Permeable Pavement Pavement Thickness ft Diameter Height in ft Underdrain E h Storage Volume at Top of Pavement act 357 n 2a ms Show Pavement Table Open Table H mi NO initia Stage tt 4 619 Total Volume Through Facility acti Total Volume Through Ares ac f 6 251 Size Pavement Target fino 5 5 2013 3 02 AM The permeable pavement dimensions and parameters are Pavement Length ft Roadway length Pavement Bottom Width ft Roadway width Effective Total Depth ft Height from bottom of permeable pavement subgrade to
7. 6 Predevelopment scenario runs okay l 7 Mitigated scenario runs okay 8 Compare SMRHM Report screen with report file l a Project location descriptions match b Precipitation gauges match c Precipitation scales match d Flow frequency results match e All flow duration values PASS o S f Any pervious PERLND landusechanges g Any impervious IMPLND landusechanges h Any scaling factor changes Y i Any duration criteria changes Y j pond dimensions match k pond outlet structure info matches 9 SMRHM pond dimensions match drawings 10 Infiltration set to YES for infiltration pond 11 Total SMRHM drainage area matches drainage maps drawings 12 Mitigated drainage area s match Predevelopment 13 Predevelopment vegetation correct IE 14 Mitigated land use areas correct 15 Routing correct 222222222 16 Check facility drawdown Gf included J a Used POC Mitigated stage b Drawdown times okay o O oo 17 Options set to default values Y 18 Other issues S o SMRHM submittal APPROVED 167 Appendix D Santa Margarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank 168 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 APPENDIX E SMRHM BACKGROUND Effects of Hydromodification Urbanization of a watershed modifies natu
8. 8163 430 288 66 Pass 8997 399 265 66 Pass 9831 365 245 67 Pass 0666 339 228 67 Pass 501 POC 1 Predeveloped flow 801 POC 1 Mitigated flow 1500 317 207 65 Pass 2334 284 187 65 Pass 3168 268 175 65 Pass 4002 258 162 62 Pass 4837 241 199 61 Pass 5671 222 139 62 Pass 6505 208 129 62 Pass 2339 191 116 60 Pass All Datasets Flow Stage Precip Evap POCI1 8173 184 106 57 Pass 9008 172 96 55 Pass 9842 164 88 53 Pass 0676 152 77 50 Pass o o o o o o o O 1 1 1 X X di 1 1 1 7329 464 326 70 Pass 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 3 16 4 2013 10 02 AM The flow duration plot for both Predevelopment and Mitigated flows will be shown along with the specific flow values and number of times Predevelopment and Mitigated flows exceeded those flow values The Pass Fail on the right indicates whether or not at that flow level the flow control standard criteria were met and the pond passes at that flow level in this example from 10 of the 2 year flow to the 10 year If not a Fail 1s shown NOTE A single Fail fails the hydromod pond design criteria 25 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM gueumuows 6uHkcooc Drawdown Analysis Select analysis lor 1001 Trapezesdal Pond 1 STAGE Mibgabed Analyze Stage Pond Pond Drain Time ds Stage feel Percent of Total Fiun Time 5 4 2013 Tr AM Pond drawdown retention time is computed o
9. GEOTEXTILE FABRICAS GEOTECH NICAL REPORT 10 FT MIN Figure courtesy of Riverside County Flood Control and Water Conservation District An infiltration trench is similar to the infiltration basin However there is no bottom discharge pipe or underdrain Water must infiltrate into the native soil underlying the gravel layer of the planter Overflow is controlled by an overflow outlet For the purpose of flow control the discharge from the overflow outlet should not exceed the predevelopment discharge from the project site for the flow duration range specified by the local jurisdiction In SMRHM the infiltration trench is represented by the gravel trench bed element 122 Santa Margarita Region Hydrology Model Guidance June 2013 Santa Margarita Region Hydrology Model File Edit View Zoom Help cr E agm pgmealUeSXew3s 5i34 u c o MM Schematic SEE SL infiltration Trench Mitigated Facility Name Infiltration Trench Outlet 1 Outlet 2 Outlet 3 Downstream Connection pa Facility Type v Precipitation Applied to Facility Quick Trench Facility Dimension Diagram MV Evaporation Applied to Facility Facility Dimensions Outlet Structure Data Trench Length ft Riser Height ft a a oO Ll e Trench Bottom Width ft i Effective Total Depth ft B jJ ques Diameter in 24 EE Bottom slope ft ft 0 01 Riser Type Flat y Left Side Slop
10. RNS ot Top Fie Sipe HA Orifice Diameter Height Infiltration Number in It 1 55 dh AH 2 p spo 4 gt sh Pond Volume at Aire Head ac ft 217 Show Pond Table OpenTae Initial Stage ft A i Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation H o Downstream Connection Overflow Elevation ff o Merations AE To save the project click on File in the upper left corner and select Save As 32 Santa Margarita Region Hydrology Model Guidance June 2013 Save As Save in C3 projects 4 e ex E3 2 Ea default whm File name My Network Save as type SMRHM Project Files Places Select a file name and save the SMRHM project file The user can exit SMRHM and later reload the project file with all of its information by going to File Open 33 Santa Margarita Region Hydrology Model Guidance June 2013 9 Exit SMRHM New Cim gzueummiows5i3iB oosc Open Ctri 0 eee rn _Recentfies o ED Save Save As a FOX E Trapezoidal Pond 1 Mitigated x Ttapezoidal Pond 1 Downstream Connections 5 JP F Preciptatan Aledo Fac AitoPond Quick Pond v Evaporation Applied to Faciity Facility Dimension Diagram Vom re eese Outlet Structure Data Facility Bottom Elevation It Riser Height It mi Bottom Length ft Riser Diameter in fig H A Riser Type Noche oi pike e FEM Notch Heig
11. Sand filter overflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch Notch Width feet width of notch cannot be larger than the riser circumference For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section Infiltration Yes infiltration through the filter material Hydraulic Conductivity 1n hr Filtration rate through the sand filter Filter material depth ft Depth of sand filter material for runoff filtration Sand filter receives precipitation on and evaporation from the sand filter surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should be checked 59 Santa Margarita Region Hydrology Model Guidance June 2013 OUTLET STRUCTURE CONFIGURA TIONS The trapezoidal pond vault tank irregular pond gravel trench bed and sand filter all use a riser for the outlet structure to control discharge from the facility Riser Diameter 3 sb AH Pomni Vokama el Peer Mead ec el 0 Show Pond Table om Tam Tide Gate Tone Senes Demand The riser is a vertical pipe with a height above pond bottom typically one foot less than the effective depth The user specifies the riser height and diameter The riser can have up to three round orifices The bottom orif
12. CD X Shub Moderate 5 10 39 CD X Shub X gteep 10 2090 10D Sm _ Very Steep gt 20 Grass Flat 0 596 Moderate 5 10 25 eB N N nm O CO OOIND N jO 0O0 0 41 Santa Margarita Region Hydrology Model Guidance June 2013 The user does not need to know or keep track of the HSPF PERLND number That number 1s used only for internal tracking purposes The user inputs the number of acres of appropriate basin land use information Pervious land use information is in the form of soil land cover and land slope For example A Grass Flat means NRCS soil type A natural grass vegetative cover and flat 0 596 land slope There are four basic soil types A well infiltrating soils B moderate infiltrating soils C poor infiltrating soils and D really poor infiltrating soils There are four basic land cover categories forest shrub grass and urban landscaped vegetation Native land cover is assumed to be grass and refers to the natural non planted vegetation In contrast the developed landscape will consist of urban vegetation lawns flowers planted shrubs and trees Urban vegetation is irrigated in SMRHM Land slope is divided into flat 0 596 moderate 5 10 steep 10 20 and very steep gt 20 land slopes HSPF parameter values in SMRHM have been adjusted for the different soil land cover and land slope categories SMRHM HSPE soil parameter values take into account the h
13. Duplicate Predeveloped gt Gate Time Series Demand Save Element ermine Outlet With Tide Gate Load Element se Tide Gate Run Predeveloped 2 Gate Elevation ft fo Downstream Connection z Id Mm rflow Elevation ft lo Iterations jo Import Basin Location v v meanma lGonAM Right click on the trapezoidal pond element to connect the pond s outlet to the point of compliance Highlight and click on Connect to Point Of Compliance 15 SMRHM santa Margarita Region Hydrology Model Guidance June 2013 File Edit View Help Summary Report Dc EB 48 amp MM Schematic apezoidal Pond 1 a Point Of Compliance Element Trapezoidal Pond 1 POC Outlet Y Qutlet 1 Move pul Di 1 dt ERES ls JASEN ossis Trapezoidal Pond 1 Mitigated DOG Facility Name Trapezoidal Pond 1 Facility Type Trapezoidal Pond Outlet 1 Downstream Connections V Precipitation Applied to Facility MV Evaporation Applied to Facility Facility Dimensions Facility Bottom Elevation ft Bottom Length ft Bottom Width ft Effective Depth ft Left Side Slope H Bottom Side Slope H V Right Side Slope H Top Side Slope H v Infiltration UIT Tide Gate Time Series Demand Outlet 2 Outlet 3 Auto Pond Quick Pond Facility Dimension Diagram Outlet Structure Data Riser Height ft lo H Riser Diameter i o H Riser Type Flat N
14. Example Sama Samuoco L Schematic at Low impact elopm Scenario Generator Quick Pond UC TEE EE EE GE EE E Total Runoff 3x s usb AT Ru soles E IMPLND NAME E A Total Runofl Roads Moo 5 10 25 13862 EXT HU is Rootes 15 13721 E ono zam naza Ca OOEEO C FF Units of Inchez s Maler Balance Chart Clase Unis of Acre t Low Tide Gate Elevation Hf O Downstream Connection z Overflow Elevation It j Iterations o 6 4 2013 4 20 PM The LID tool bar button farthest on the right brings up the Low Impact Development Scenario Generator screen The LID scenario generator can be used to compare the amount of runoff from different land types and combinations The user can quickly see how changing the land use affects surface runoff interflow groundwater and evapotranspiration NOTE The LID scenario generator works only in the Mitigated scenario 110 SMRHM File Edit View Help Summary Report Dc E 368 m Move Elements e Save x y Load x y E gi al dle Santa Margarita Region Hydrology Model Guidance June 2013 DMA Name Surface Flows To Area in Drainage Management rea Available Pervious Acres BlrbanMod 5 10 M BUbansteslo20 7 0 CO ForestFlai0 5 J o 7 UD Forest Mod 5 10 fo PCO Forest St10 20 fo PCO ForestVeyo20 JO 1 o E DShubFaosz 0 Y C OShubModS10
15. J o TA CD Shubstlo2x Jo CShubVeyp20 Jo p CD Brass Flai052 _ jv C D GrassModi510z D 1 TF C D GrassSteft020 JO C DGrasVeyp207 Jo C DUlbanFlai05 J o v C DUanMod5ing i Jr Emus fo lr Ora gt PerviousT otal Aces m Acre Aces Impervious Total DMA Total Deselect Zero Interflow DESK EH Or Se oc DMA 4 Designate as Bypass for POC Groundwater Show Only Selected Available Impervious Acres a F Roads Flat 0 5 Bees Pme 0 Select By GD 5 4 2013 4 36 PM The easiest way to compare different land use scenarios 1s to place all of them on the same Schematic Editor screen grid Each DMA can then represent a different land use scenario Because the LID scenario generator only compares runoff volume there 1s no need to do any routing through a conveyance system or stormwater facility For this example the four DMAs are assigned the following land uses DMA 1 1 acre A Grass Moderate 5 10 DMA 2 1 acre C Shrub Moderate 5 10 DMA 3 1 acre C Grass Moderate 5 109406 DMA 4 1 acre D Urban Moderate 5 10 Each basin is assigned a different POC point of compliance for the LID analysis 111 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM File Edit View Help Summary Report Don soe AE MAA IPS LID Scenario Generator POC To Analyz
16. Sand filter underdrain bottom 1 in above bottom gravel layer No infiltration to native soil 135 Santa Margarita Region Hydrology Model Guidance June 2013 EXTENDED DETENTION BASIN SIDE SLOPES NO STEEPER THAN 4H 1V U BASIN GUI ISSUED BY THE ENGINEERING PA OR PLANNING AUTHORITY FOREBAY VOLUME 3 5 OF Vp SURFA INFLOW INFLOW 1 m r PAVED BOTTOM HERWISE PER D R OTHER GUIDELINES AUTHORITY ISTRICT SIZE NOT 1 pda WER BAY INVERT OF VOLUME IN 5 MINUTES 48 W X 24 D GRAVEL FILLED LOW FLOW TRENCH WATER SURFACE COLLECTOR TRENCH FILTER DRAIN PERFORATED PIPE SUBDRAIN OUTLET WITH TRASH PER WQ501 SECTION A A LOW FLOW TRENCH MIN eye ls WOL 0 5 LOWEST fy ORIFICE A al SEE WQ501 T DETAILS AASHTO NO 57 OR 87 COARSE AGGREGATE LAYER 2 FINE AGGREGATE PER ASTM C 33 3 AASHTO NO 2 GRAVEL LAYER GENERAL NOTES 1 SEE RIVERSIDE COUNTY FLOOD CONTROL DISTRICTS APPENDIX B UNDERDRAINS OR ADDITIONAL INFORMATION REGARDING F UNDERDRAINS 2 SEE RIVERSIDE COUNTY FLOOD CONTROL DISTRICT3 APPENDIX C BASIN GUIDELINES FOR ADDITIONAL GENERAL BASIN INFORMATION Figure courtesy of Riverside County Flood Control and Water Conservation District The extended detention basin is a combination stormwater pond forebay gravel trench connector trench and sand filter filter drain In SMRHM there is not a single element that represents this combination 136 Santa
17. Target fino ACA Or SBE Downstream Connections Facility Dimension Diagram Outlet Structure Data Rze Hett D Riser Dismetes n 0 a ReeType Fa Motch Type Orifice Diameter Height Number in ft ib sih ilo lU zaj Um JE Filter Storage Volume at Rice Head ac4tj 000 Show Filter Table Initial Stage ft Open Tae H pd 5 4 2013 302 PM The sand filter is a water quality facility It does not infiltrate runoff but is used to filter runoff through a medium and send it downstream It can also have one or more surface outlets represented by an outlet structure with a riser and multiple orifices The user must specify the facility dimensions bottom length and width effective depth and sideslopes The hydraulic conductivity of the sand filter and the filter material depth are also needed to size the sand filter default values are 1 0 inch per hour and 1 5 feet respectively NOTE When using the sand filter element check with Appendix C or the local municipal permitting agency to determine the required treatment standard percent of the total runoff volume treated by the sand filter SAND FILTER EFFECTIVE DEPTH BOTTOM LENGTH FILTER MATERIAL OBRA 58 Santa Margarita Region Hydrology Model Guidance June 2013 The filter discharge 1s calculated using the equation Q K I A where Q 1s the discharge in cubic feet per second cfs K equals th
18. duration criteria for curve matching If so proceed with the pond design using the revised outlet 4 If the revised design shows Fail scoring at one or more flow levels excess flow durations may be reduced somewhat by reducing the depth of the pond which lowers the head above the orifice As an alternative further mitigation can be applied to the low flow orifice flow by adding an additional infiltration measure 162 Appendix C Santa Margarita Region Hydrology Model Guidance June 2013 downstream This can be sized either approximately by estimating an average excess flow from the orifice or with the help of SMRHM by returning to the screen for the pond characteristics and specifying a different Downstream Connection for the bottom orifice which is then connected to an additional element With this revision to the post project scenario the POC for the system would then be located at the downstream end of the additional low flow mitigation Alternative Outlet Configurations SMRHM has two default types of outlet configurations multiple orifice or orifice plus weir notch based on a standpipe riser structure detailed in the SMMWW The entire standpipe is usually within a cylindrical enclosure or manhole to exclude trash and larger particles that could clog the outlet The SMMWW notes that orifices can also be placed on a tee section or a vertical baffle within the same type of enclosure An alternative configuration is a flat headwall wi
19. requires the use of a continuous simulation hydrologic model To facilitate this design approach Clear Creek Solutions CCS has created a user friendly automated modeling and flow duration control facility sizing software tool adapted from its Western Washington Hydrology Model WWHM The WWHM was developed in 2001 for the Washington State Department of Ecology to support Ecology s Stormwater Management Manual for Western Washington and assist project proponents in complying with the Western Washington hydromodification control requirements The Santa Margarita Region Hydrology Model SMRHM is adapted from WWHM Version 4 but has been modified to represent Riverside County hydrology and enhanced to be able to size other types of control measures and low impact development LID techniques for flow reduction as well SMRHM is a useful tool in the design process but must be used in conjunction with local design guidance to ensure compliance for specific projects The reader should refer to Appendix C and local stormwater program guidance for additional information and suggestions for using the SMRHM 1 Washington State Department of Ecology 2001 Stormwater Management Manual for Western Washington Volume Ill Hydrologic Analysis and Flow Control Design BMPs Publication No 99 13 Olympia WA 169 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM Overview The SMRHM software architecture and methodology is th
20. 3 Run Predevelopment and Mitigated scenarios 4 Goto Analysis screen and check flow duration results 5 If pond passes flow duration criteria then decrease pond dimensions 6 If pond fails flow duration criteria then change in order of priority bottom orifice diameter riser notch width pond dimensions 7 Tterate until there is a good match between Predevelopment and Mitigated flow duration curves or fatigue sets 1n Pond input information Bottom Length ft Pond bottom length Bottom Width ft Pond bottom width Effective Depth ft Pond height from pond bottom to top of riser plus at least 0 5 foot extra Left Sideslope H V ratio of horizontal distance to vertical O zero for vertical pond sides Bottom Sideslope H V ratio of horizontal distance to vertical O zero for vertical pond sides Right Sideslope H V ratio of horizontal distance to vertical O zero for vertical pond sides Top Sideslope H V ratio of horizontal distance to vertical O zero for vertical pond sides Riser Height ft Height of overflow pipe above pond bottom Riser Diameter 1n Pond overflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch Notch Width feet width of notch cannot be larger than the riser circumference For more information on riser notch options and orif
21. 764867 Riser Diameter in 18 Bottom Width ft 67 764867 Riser Type Notched 4 Effective Depth ft Nath Tope TT ai Left Side Slope H Notch Height ft 0 7203 a Bottom Side Slope H Notch Width t is x 15 4 Right Side Slope HA Top Side Slope H v Drainage Elements Orifice Diameter Height I JI amp j Gol co _ j ale n3 n3 DIVA TrapezoidalPond 1 Infiltration No Number in ft SCENE 1 fis Ho mo o 25 3 o l Pond Volume at Riser Head ac ft 2171 Show Pond Table OpenTable Initial Stage ft Commercial Toolbox Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft lo Downstream Connection lo Iterations lo Move E 4 ey MA aa Ka Y p4 1 it sij E Overflow Elevation ft lt 6 4 2013 10 00 AM The final pond dimensions bottom length bottom width effective pond depth and sideslopes and outlet structure information riser height riser diameter riser weir type weir notch height and width and orifice diameter and height are shown on the trapezoidal pond screen to the right of the Schematic grid NOTE If Auto Pond selects a bottom orifice diameter smaller than the smallest diameter allowed by the local municipal permitting agency then the user has the option of specifying a mi
22. Depth Pervious Pipe Bottom Length and orifices see discussion in OUTLET To use the underdrain click the Underdrain Used box and input an underdrain pipe diameter feet underdrain outlet orifice diameter inches and offset inches The offset defines the height of the bottom of the underdrain pipe above the bottom of the lowest amended soil layer 82 Santa Margarita Region Hydrology Model Santa Margarita Region Hydrology Model Guidance June 2013 Eje Edt Wew Hep ummary Report AS asc Schematic Run le Scenario SSe nm 1 d Hitigated Tem o Liv m it ajo ea Use simple swale Underdrain Used Swale Bottom Elevation ft 0 Edit Sail Types KSat Safety Factor Mona C 2 Native Infiltration Default Swale Underdrain Diameter ff o Offset in Orifice Diameter in lo Hp Flow Through Underdrain lact 0 Total Quiflow act Ww LJ utlet Structu O re Data Rise Quiet Shuchure zaj Outlet Structure Data Riser Height Above Swale surface M p ed Riser Diameter fin fp H Rise Type Fia y Orifice Diameter Height Number im ft ih zih lt 2 b dp o 4 b Sp Show Swale Table OpenTable H ale Volume of Fee Head ac ft 6 4 2013 330 PM The amended soil layer fills with stormwater from the top on down to where it can drain to the native soil Gf Native Infiltration is set to YES and or the underdrain p
23. Dimension Diagram Outlet Structure Data Biser Height i lo Ad Piser Diameter n H Riser Type Fig H Hotch Type Orifice Diameter Height Humber in tt ib fo milo co 2 3 o sih 4 Pond Volume at ier Head act Show Pond Table Oper Table Initial Stage ff E Tide Gate Elevation H o Downstream Connection Overflow Elevation ft i Iterations lo 5 4 2013 31 AM The point of compliance is shown on the pond element as a small box with the letter A and number 1 in the bar chart symbol in the lower right corner NOTE The letter A stands for Analysis and designates that this is an analysis location where flow and stage will be computed and the output flow and stage time series will be made available to the user The number 1 denotes that this is POC 1 You can have an analysis location without having a point of compliance at the same location but you cannot have a point of compliance that is also not an analysis location 17 Santa Margarita Region Hydrology Model Guidance June 2013 5 Sizing the trapezoidal pond SMRHM Dg De el ee i Poe of ee eli I Schematic d AA Facility Dimensions Facility Bottom Elevation It OF min 2 10 min gt NL Miti Fast Pond Depth incl 1 ft freeboar ar m Pond length to width ratio 11091 Pond Side Slopes 3 to 1 Bottom Length Ji Bottom wien Ta Volume at meer head Choos
24. EA LETAR IrL lt i Trapezoldal Pond 1 Mitigated Facility Type Trapezoidal Pond Outlet 1 Outlet 2 Outlet 3 Downstream Connections Auto Pond ij Quick Pond Facility Dimension Diagram Facility Dimensions Facility Bottom Elevation It Bottom Length It IF HSPF Input File Import Export gl e ew Dis Penndz Fica zs uE vm 1t al 6 4 2013 ETZ PM The Tools screen is accessed with the Tools tool bar second from the right The two purposes of the Tools screen are 1 To allow users to view SMRHM HSPF PERLND parameter values See Appendix A for a list of the SMRHM HSPF PERLND parameter values 2 To allow users to export time series datasets 106 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM Example puse Hm AA oc el t si Trapezoidal Pond 1 Mitigated d Hiligated acil Facility Type Trapezoidal Pond Outlet 1 Outlet 2 Outlet 3 Downstream Connections Auto Fond Quick Pond Facility Dimension Di j Facility Dimensions Facility Bottom Elevation It Bottom Length It Standard Import Features GIS Import SSD Import Element Connection HSPF Input File Irmport E pert EID TELSINDRE EVAP P 15 2 Temecula Valey 1115122 IRRIGATION IN INCHES 1151501 POC 1 Predeveloped flow PF 115 1701 inflow lo POC 1 Maxgated J eR FL abel fiov F115 1000 Trapercedal Pond 1 ALL OUTLETS Mitigabed 5 15 1001 Trapezesdal Pond 1 STAGE Mitigated 2011 03 30 24 0
25. Equation 1 controls the infiltration rate into the top soil layer f g 1 010 Equation 1 f soil surface infiltration rate cm hr g soil porosity of top soil layer 0 soil moisture content of top soil layer o suction head at the wetting front cm F soil moisture content of the top soil layer cm d surface ponding depth cm K hydraulic conductivity based on saturation of top soil layer cm hr K relative hydraulic conductivity can be computed using the following Van Genuchten approximation equation Van Genuchten approximation of relative hydraulic conductivity Equation 2 where K 0 relative hydraulic conductivity K saturated hydraulic conductivity 0 water content 0 residual water content 0 porosity a constant n constant m constant A few 1ssues arise when dealing with multiple subsurface soil layers The K value used in Equation 1 must be computed from the top soil layer Infiltration into the upper soil layer must not exceed the lesser of the maximum percolation rates for each of the soil layers Finally the rate of percolation of the top layer may be reduced because the layer or layers beneath the top layer cannot accept the percolation flux because of existing saturation levels 175 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 Water storage and movement through the three subsurface layers will be computed using Darcy s equation as shown
26. For the purpose of flow control the discharge from the overflow outlet should not exceed the predevelopment discharge from the project site for the flow duration range specified by the local jurisdiction In SMRHM the infiltration basin 1s represented by the trapezoidal or irregular shaped pond element 119 Santa Margarita Region Hydrology Model Guidance June 2013 Santa Margarita Region Hydrology Model File Edit View Zoom Help cy E tag pgmgIlREHS53 90w3Bui voco MM Schematic SEE i Infiltration Basin Mitigated Facility Name Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections P amp Je V Precipitation Applied to Facility Auto Pond Quick Pond 4 Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft o FER HORE B Bottom Length ft Riser Diameter in 24 gt Bottom Width ft Riser Type Flat Effective Depth ft HM Notch Type i Left Side Slope HV pa Bottom Side Slope H fa Right Side Slope Hv fa O aee T pp Orifice Diameter Height Infiltration ves Number in ft Measured Infiltration Rate in hr Bo jo ah Reduction Factorfinfilt factor o5 gt ai Use Wetted Surface Area sidewalls No Wh lt Total Volume Infiltrated ac ft 400 83 Total Volume Through Riser ac ft 0 Pond Volume at Riser Head ac
27. Merations o FTT E E i z 6 4 2013 4 10 PM The Reports tool bar button fourth from the left brings up the Report screen where the user can look at all of the project input and output The project report can be saved or printed The project report contains the project input information provided by the user and a summary of the project output information produced by SMRHM The project report can be generated as either a Microsoft Word file or a PDF file 104 Santa Margarita Region Hydrology Model Guidance June 2013 wy Example1 rtf Microsoft Word acia Type a question for help X SMRHM PROJECT REPORT Project Name Examplel Site Name Site Address City 3 Report Date 6 4 2013 Gage Temecula Valley Data Start 1974 10 01 Data End 2011 09 30 Precip Scale 1 00 Version 2013 05 13 Low Flow Threshold for POC 1 10 Percent of the 2 Year High Flow Threshold for POC 1 10 year PREDEVELOPED LAND USE Name DMA 1 Bypass No GroundWater No Pervious Land Use Acres C D Grass Mod 5 10 10 Pervious Total 10 v 2 Impervious Land Use Acres o 7 T vam m ama Ma 1 n lw Example 1 rtf 12 338 characters an approximate value This 1s an example of the project report in the format of a Microsoft Word file RTF format 105 Santa Margarita Region Hydrology Model Guidance June 2013 TOOLS SCREEN SMRHM Example
28. Mod 5 10 po RC 8 Urban Flat o 5 lp 1 Roads Steep 10 20 fo ki M B Urban Mod 5 102z p m Roads VeryStee gt 20 po Isconne emen Disconnect POC B Urban Stee 10 20 p jJ Roof Area BUranVeySp20 Jo O Driveways Flat 0 5 io ete C FoesFlo5 gt DiewasModbiUg JE OO Cut Element C D Forest Mod 5 10 Dp jJ Driveways St 10 20 po Copy Element C D Forest St 10 20 o Driveways Very 20 D 1 desino C D Forest Very gt 20 p jJ Sidewalks Flat 0 5 z po Duplicate Predeveloped C D Shrub Flat 0 5 o Sidewalks Mod 5 10 o C D Shrub Mod 5 10 p jJ Sidewalks St 10 20 po Save Element z sc C D Shubst 10 20 o Sidewalks Very gt 20 lo px C D Shrub Very gt 20 p jJ Parking Flat 0 5 o Run Predevelope v z Rus Hn C D Grass Flat 0 5 o Parking Mod 5 10 Dp Clear All v C D GrassMod5 10 Parking Steep 10 20 po C D GrassSte 10 20 o Parking Very 20z po Import Basin Location C D GrassVery gt 20 D jJ Pond Area po dr CO Uan Fasa Move pu PerviousT otal Acres lt a 4p Impervious Total Actes JI DMA Total Acres Save xy Load x usta fuss DeselectZero Select By GO k gi lt 6 4 2013 3 20AM The downstream discharge from this DMA will be selected as our point of compliance for the Predevelopment scenario Right clic
29. Sees Type a question for help X E default rtf Microsoft Word t yi rt Format Tools Table Window Help Adobe PDF a t EE E zi x ru x SMRHM PROJECT REPORT Project Name default Site Name Site Address City 3 Report Date 6 4 2013 Gage Temecula Valley Data Start 1974 10 01 Data End 2011 09 30 Precip Scale 1 00 Version 2013 05 13 Low Flow Threshold for POC 1 10 Percent of the 2 Year High Flow Threshold for POC 1 10 year PREDEVELOPED LAND USE Name DMA 1 Bypass No GroundWater No Pervious Land Use Acres C D Grass Mod 5 10 10 Pervious Total 10 v n Impervious Land Use Acres o z T mm o meri oma TA n Scroll down the Report screen to see all of the results 3l Santa Margarita Region Hydrology Model Guidance June 2013 8 Save project New Cun Ameumuewsamu ccc El P al Trapezoidal Pond 1 Mitipated x ped Mitigated iy Name Trapezcidal Pond 1 Facility Type TiapezodsPond Outlet 1 Outlet 2 Outlet 3 Downstream Connections p Je JE 1 V Precipitation Applied to Faciity QuickPond RV Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facil Bottom Elevation EJ Rie Hagati 3 H Bottom LENTA i A RiserDiameterfn ig 24 e pO posle EI Left Side Slope HA Hotch Haight AI fies a Bottom Side Slope HA Notch Widh cU Right Side Slope HN
30. The user inputs the number of acres of each land cover and the model calculates the runoff coefficient C 101 Santa Margarita Region Hydrology Model Guidance June 2013 w BMP Design El JES Class 2 Base Gravel or Class 2 Permeable Base Pervicus Concrete Porous Asphalt Open and Porous Pavers Turf block Ornamental Landscaping Natural A Soil Natural B Soil Natural Soil Natural D Soil Mixed Surface Types Calculate the composite Runoff Coefficient C for the BMP Tributary Area Use the folowing equation based on the WEF ASCE Method C 0 85812 0 78I2 0 7741 0 04 C 039 Determine Design Storage Volume Vaw Calculate Vo the 85 Unit Storage Volume Vu Ds 5X C V 0 89 m acyac 12 n ft EMP Design Flow Rate g p CxIx Ar Click on the Calculate button at the bottom of the screen to calculate the BMP design volume Vgwp and flow rate Opmp 102 Santa Margarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank 103 Santa Margarita Region Hydrology Model Guidance June 2013 REPORTS SCREEN SMRHM Example ose xi dag ma Ow Sh BBs o SI N i Schematic m OIX SU Trapezoidal Pond 1 Mitigated x Outlet 1 Downstream Connections suis Ka nll oe Es zre Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ff U Downstresm Connection y Overflow Elevation ff 0
31. Wew Heb Summary Report Deb x gis eS Oe Sa es o ie ee en S Bes Schematic fi x at Bio Swale 1 Mitigated 4 Mitigated Facility Name i Outlet 1 Downstream Connection Facility Type Bioretenlicn Swale l Use simple swale Default Swale Underdrain Used Swale Bottom Elevation f 0 Swale Dimensions Flow n Vnd He Outlet Structure Data RieOuleSbuctue 1 1 7H Outlet Structure Data Riter Height Above Swale suface MJ p Riser Diameter in p Rise Type Fim Y Orifice Diameter Height Humber in ft EditSoil Types 3 me KSat Safety Factor 3 b i None C 2 Show Swale Table OpenTable Sle Volume at Fires Head act Native Infiltration Ho 6 4 2013 328 PM 81 Santa Margarita Region Hydrology Model Guidance June 2013 The input information required for the riser outlet structure is Riser Height above Swale Surface feet depth of surface ponding before the riser 1s overtopped Riser Diameter inches diameter of the stand pipe Riser Type Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch Notch Width feet width of notch cannot be larger than the riser circumference For more information on riser notch options STRUCTURE CONFIGURATIONS section BIORETENTION SWALE Effective
32. With Tide Gate Use Tide Gate Tide Gate Elevation ft Downstream Connection Overflow Elevation ft U Herations o 6 4 2013 9 30 AM A line will then be shown connecting the DMA to the trapezoidal pond 14 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM File Edit View Help Summary Report Dc E X Ba AASEN Or Suul oOo E Schematic I EX 3X Trapezoidal Pond 1 Mitigated ES Predeveloped KITE Facility Name Trapezoidal Pond 1 Facility Type Trapezoidal Pond a Outlet 1 Outlet 2 Outlet 3 Downstream Connections V Precipitation Applied to Facility Auto Pond Quick Pond gt V Evasion Applet Faci Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft fs Riser Height ft D Bottom Longs ft fo Riser Diameter in g Bottom Width t fs Riser Type Flat H Effective Depth ft o Nach Tope Left Side Slope HV o Bottom Side Slope HV p Right Side Slope HA fs leia Hu p Orifice Diameter Height 4 nfiltration no Number in ft i Element On Lis x 2 Connect To Element VE H Connect to Point Of Compliance 2 o o ET Analyze 3 o o sej Disconnect Element Disconnect POC Pond Volume at Riser Head ac ft D Find Bement Show Pond Table OpenTable Cut Element Initial Stage ft Copy Element Delete Element
33. automated optimization process to calculate the pond size and outlet structure dimensions NOTE Depending on the complexity of the project the length of the precipitation record and the computational speed of the computer Auto Pond may take 1 to 15 minutes to run Running Auto Pond automates the following SMRHM processes 1 the 15 minute Predevelopment scenario runoff is computed for the 30 50 years of record it varies depending on the rain gauge used 2 the Predevelopment runoff flood frequency is calculated based on the partial duration peak flows 3 the range of flows is selected for the flow duration 10 of the 2 year peak to the 10 year peak this flow range is divided into 100 increments and the number of 15 minute Predevelopment flow values that exceed each flow increment level Predevelopment flow duration are counted to create the flow duration curves and accompanying tabular results ae Next SMRHM computes the post development runoff in the Mitigated scenario and routes the runoff through the pond But before the runoff can be routed through the pond the pond must be given dimensions and an outlet configuration Auto Pond uses a set of rules based on the Predevelopment and Mitigated scenario land uses to give the pond an initial set of dimensions and an initial outlet orifice diameter and riser the riser is given a default rectangular notch This information allows SMRHM to compute a stage storage discharge
34. b n it al gt il 5 4 2013 250 PM A storage tank is a cylinder placed on its side The user specifies the tank s diameter and length Auto Tank and Quick Tank work the same way as Auto Pond and Quick Pond Go to page 48 to find information on how to manually size a vault or other HMP facility NOTE Auto Tank is available only in the Mitigated scenario There is a Quick Tank option that creates a tank but does not check for compliance with the flow duration criteria TANK Tank input information CIRCULAR Tank Type Circular or Arched TT For Circular Diameter ft Tank diameter Length ft Tank length For Arched Height ft Tank height DIAMETER LENGTH 51 Santa Margarita Region Hydrology Model Guidance June 2013 Width ft Tank width at widest point Length ft Tank length Riser Height ft Height of overflow pipe above tank bottom must be less than tank diameter or height Riser Diameter 1n Tank overflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top of the weir to the bottom of the notch Notch Width feet width of notch cannot be larger than the riser circumference TANK ARCHED For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section or LENGTH Infiltration Yes infiltration into the unde
35. below q K z Eguation 3 Z Where q Darcy flux cm hr K hydraulic conductivity of the porous medium cm hr h total hydraulic head cm z z elevation cm The total head h is the sum of the matric head y and the gravity head z h w z Equation 4 Substituting for A yields ae Equation 5 dz 176 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 Hydraulic conductivity and matric head vary with soil moisture content These values can be computed by solving the Van Genuchten s equation Equation 6 for both values Note that y 0 when the soil 1s saturated Van Genuchten Equation to calculate total head ie loq 7 Equation 6 a SE 2 where A total hydraulic head a constant SE effective saturation m z constant n constant and z elevation head Effective saturation SE can be computed using the following Van Genuchten equation Van Genuchten Equation to calculate effective saturation 0 0 1 ay 0 0 1 LSF Equation 7 where 8 water content 0 residual water content porosity a constant y 1 n z constant 1 m constant RN A A z pore size distribution index y lt bubbling pressure y pressure head h z h total hydraulic head z elevation head and SE effective saturation Ignoring z elevation head results in h hm matric head Evapotranspiration is an important component
36. compliance The number 1 next to the letter A is the number of the POC POC 1 86 Santa Margarita Region Hydrology Model Guidance June 2013 CONNECTING ELEMENTS Santa Margarita Region Hydrology Model File Edit View Help Summary Report Dci t Bw MM Schematic Move Elements i mnmusuesmeow ddHEiio5oo SE lt DMA 1 Mitigated DMA Name Flows To Area in Drainage Management rea Available Pervious Acres Disconnect Element Disconnect POC e AForest Flat 0 5 Ar afosa Jp Connect to Point Of Compliance AForest Stee 10 20 p A Forest Very 2027 fos Find Element A Shrub Flat 0 5 p A Shrub Mod5 10 p Sid A Shrub Stee 10 20 Cut Element Copy Element Delete Element Duplicate Predeveloped psd Save Element Load Element A Grass Very S 20 p A Urban Flat 0 5 Run Predeveloped Run Mitigated Clear All A Urban Mod 5 10 A Urban Stee 10 20 fs AUrbanVey Sp 20 po B Forest Flat 0 5 pp e B Forest Mod 5 10 p sir B Forest Stee 10 20 pp PerviousT otal Poo Acres Impervious Total pp Acres DMA Total pp Acres Designate as Bypass for POC Surface Interflow Groundwater Show Only Selected Available Impervious Acres a Roads Flat 0 5 D Rufe 8 Pme 6 JJ Save x
37. consulted that is external to the SMRHM software either provided in Appendix C of this guidance documentation or by the local municipal permitting agency Purpose The purpose of SMRHM is to size hydromodification management or flow control facilities to mitigate the effects of increased runoff peak discharge duration and volume from proposed land use changes that impact natural streams wetlands and other water courses SMRHM provides e A uniform methodology for Santa Margarita Region County e A more accurate methodology than single event design storms An easy to use software package Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM is based on Continuous simulation hydrology HSPF Actual long term recorded precipitation data Measured pan evaporation data Existing vegetation for predevelopment conditions Regional HSPF parameters Computer Requirements Windows 2000 XP Vista 7 8 with 300 MB uncompressed hard drive space Internet access only required for downloading SMRHM not required for executing SMRHM Pentium 3 or faster processor desirable Color monitor desirable It is important to know the following information prior to using SMRHM for a project e Knowledge of the site location and or street address Knowledge of the actual distribution of existing site soil by category A B C or D Knowledge of the actual distribution of existing and proposed site land cover by category f
38. dd 125 BIORETENTION STANDARD DESIGN Lat 128 BIORETENTION VERTICAL SIDESLOPES Fabi 130 BIORETEN HON PLANTER BOX encata 132 SANDFILEER BASIN oer a EE tea eae eae 134 EXTENDED DETENTION BASIN esa E 136 APPENDIX A DEFAULT SMRHM HSPF PERVIOUS PARAMETER VALUES 140 APPENDIX B DEFAULT SMRHM HSPF IMPERVIOUS PARAMETER VALUES 157 APPENDIX C ADDITIONAL GUIDANCE FOR USING SMRHM 161 Initiation Reduction Factor asa Oe a aate Reid edes deo uaa udi 161 Flow Duration Outlet Structures Practical Design Considerations 162 Drawdown time and treatment vector considerations oooooonnncnnnnnnnnnnnanannnnnnnnnnnnnnnos 163 APPENDIX D SMRHM REVIEWER CHECKLIST eene 167 APPENDIX E SMRHM BACKGROUND sua iia 169 Effects of Hydromodification a E Re base to A eR ed tue e bets 169 Development of the Santa Margarita Region Hydrology Model 169 SMRAMONVERVIEW PC Pt 170 BIORETENTION MODELING METHODOLOGY eene 172 vi Santa Margarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank vil Santa Margarita Region Hydrology Model Guidance June 2013 INTRODUCTION TO SMRHM SMRHM is the Santa Margarita Region Hydrology Model SMRHM is based on the WWHM Western Washington Hydrology Model stormwater modeling software platform WWHM was originally developed for the Washington State Dep
39. e e e m Move Elements e ease Y fig H Er dle lt 6 5 2013 231 PM O The bioretention dimensions and parameters to adjust to represent the bioretention standard design are discussed on page 81 The Riverside County Design Handbook for Low Impact Development Best Management Practices specifies the following criteria for bioretention vertical sideslopes Min width 2 ft Sideslope 0 to 1 Max ponding depth 0 5 ft Mulch top layer 2 to 3 inches deep above amended soil layer Min amended soil layer depth 1 5 ft Max amended soil layer depth 3 ft Max amended soil porosity 0 30 Max gravel layer 1 ft below amended soil layer Gravel layer porosity 0 40 Min underdrain diameter 0 5 ft No infiltration to native soil 131 Santa Margarita Region Hydrology Model Guidance June 2013 BIORETENTION PLANTER BOX Bioretention in the form of a planter box allows stormwater to enter the bioretention facility above ground and then infiltrate through the mulch layer engineered soil media and gravel storage layers before exiting through a discharge pipe For the purpose of flow control the discharge from the pipe should not exceed the predevelopment discharge from the project site for the flow duration range specified by the local jurisdiction In SMRHM the planter box bioretention 1s represented by the bioretention element SMRHM File Edit View Zoo
40. inches SURS Initial surface runoff inches UZS Initial Upper Zone Storage inches IFWS Initial interflow inches LZS Initial Lower Zone Storage inches AGWS Initial Active Groundwater storage inches GWVS Initial Groundwater Vertical Slope feet feet 150 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 Table 6 SMRHM HSPF Pervious Parameter Values Monthly Interception Storage inches PERLND No JAN TED MAR APR MAY JUN JUL AUG EP OCT NOV DEC pists pis bo bo b2 zo zo peo beo bao pie 2 p 15 pi5 015 020 pao pao pao pao pao pao pao pia 8 Pas 015 015 p20 p20 pao po p20 pao pao 020 tg 6 1 p1i3 p13 pi3 014 pi5 015 015 015 015 0415 pi4 pi e 1 p1i3 pta pi3 pi4 pi5 15 015 015 015 015 pi4 pia 9 1 p12 p12 ptz pti pio pito pto 010 pio pio tt pta 24 IS pas p13 Di pi p15 Dis 018 016 p15 b14 018 on s pia bi pie bn oi bio pio bio bio bio br br 27 it p12 ptz 011 pto pio pto pio pio pio pti pto 152 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 31 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 0 11 153 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 Table 7 SMRHM HSPF Pervious Parameter Values Monthly Lower Zone Evapotranspiration PERLND No WAN FEB MAR APR MAY JUN JUL A AUG SEP OCT NOV DEC v ps
41. layer is more restrictive This is determined by using Darcy s equation to compute flux for each layer at the current level of saturation The layer with the more restrictive flux 1s the layer that becomes saturated for that time step The next time step the same comparison is made The rate and location of water discharging from the soil layer 1s determined by the discharge conditions selected by the user There are four possible combinations of discharge conditions 1 There is no discharge from the subsurface layers except for evapotranspiration This means that there is no underdrain and there is no infiltration into the native soil Although this discharge condition is unlikely we still need to be able to model it 2 There is an underdrain but no native infiltration Discharge from the underdrain is computed based on head conditions for the underdrain The underdrain 1s configured to have an orifice It 1s possible for the orifice to be the same diameter as the underdrain With a maximum of three soil layers determining head conditions for the orifice is complicated Each modeled layer must overcome matric head before flow through the underdrain can begin Once matric head is overcome by gravity head for all of the layers then the underdrain begins to flow The flow rate is determined based on the ability of the water to move through the soil layers and by the discharge from the orifice whichever is smaller Head conditions are determ
42. may be of interest to project designers include e Pages 3 2 through 3 18 illustrate several types of roof downspout controls simple pre engineered designs for infiltrating and or dispersing runoff from roof areas in order to reduce runoff volume and or increase potential groundwater recharge o Pages 3 50 to 3 63 discuss outlet control structures their maintenance and source equations modeled into WWHM and SMRHM 165 Appendix C Santa Margarita Region Hydrology Model Guidance June 2013 e Pages 3 75 to 3 93 regarding Infiltration Reduction Factor Urban Storm Drain Criteria Manual by the Denver Urban Drainage and Flood Control District is on the Web at http www udfcd org downloads down critmanual htm Volume 3 covers design of stormwater treatment measures including extended detention basins on pages S 66 through S 77 and structural details shown on pages SD 1 to SD 16 Although these designs are not presented for hydromodification management control the perforated plate design concept allows fine tuning of drawdown times and is adaptable for use in flow duration facilities 166 Appendix D Santa Margarita Region Hydrology Model Guidance June 2013 APPENDIX D SMRHM REVIEWER CHECKLIST MRHM Reviewer Checklist Received SMRHM project WHM and WH2 files Received SMRHM WDM WDM file Received SMRHM report DOC file Project WHM file loads okay 5 Project location matches location on SMRHM screen
43. measure design with the applicable jurisdiction Flow Duration Outlet Structures Practical Design Considerations Low flow Orifice Sizing The diameter of the low flow bottom orifice is an important design parameter for flow duration facilities since flows discharged through this outlet should be at or below the project threshold for controlled flows Qcp However maintenance and or other practical considerations may dictate a practical limit to how small this orifice may be which may be larger than the optimal theoretical diameter determined by Auto Pond As an example Riverside County specifies a minimum orifice diameter of 1 0 inch While the user can manually set a minimum size for the low flow orifice doing so before running Auto Pond is not recommended as this may impair the program s ability to optimize the pond configuration The following general approach is suggested for designing a pond when there is a small value for the low end of the flow matching range l First estimate the minimum pond volume allowing Auto Pond to freely determine the diameter and placement of all orifices 2 Then manually accept all of the pond settings except low flow orifice diameter Set the low flow orifice to the desired minimum size after consulting the local municipal permitting agency 3 Manually run the mitigated scenario as described on page 48 and review the Analysis screen to check if the revised mitigated flow still passes the flow
44. soil layer depth 3 ft Max amended soil porosity 0 30 Max gravel layer 1 ft below amended soil layer Gravel layer porosity 0 40 Min underdrain diameter 0 5 ft No infiltration to native soil 129 Santa Margarita Region Hydrology Model Guidance June 2013 BIORETENTION VERTICAL SIDESLOPES VARIES 2 MINIMUM CALTRANS D73 TYPE 6 1 OR FUNCTIONAL EQUIVALENT DROP INLET WHEELSTOP AS NEEDED PONDING DEPTH WHEELSTOP AS NEEDED G MAXIMUM PARKING TYP JA m PARKING TYP r T 3 7 CT Y FI zali SS LE Y YE VOV VOV YN EE pz LLL si 1 E A ALLE MATURE VEGETATION 18 36 EE IN EZ 5205 et AND 2 3 MULCH LAYER gt gt ENGINEERED ld sco vue de dm SOIL MEDIA Fs t p k ua A PE Sra Weil aem RETAINING VALL TYPE LA PER zoe 6 PERFORATED PIPE TIESUBDRAIN CALTRANS STANDARD B3 3 OR INTO INLET i ENGINEERED ALTERNATIVE BASED ON GEOTECHNICAL PARAMETERS Figure courtesy of Riverside County Flood Control and Water Conservation District Bioretention with vertical sideslopes allows stormwater to enter the bioretention facility above ground and then infiltrate through the mulch layer engineered soil media and gravel storage layers before exiting through a discharge pipe For the purpose of flow control the discharge from the pipe should not exceed the predevelopment discharge from the project site for the flow duration range specified by the local jurisdicti
45. the Time Series element To link the external time series to SMRHM the user clicks on the Choose WDM button and identifies the external WDM file The external WDM s individual time series files are shown in the Time Series Out box The selected input dataset is the time series that will be used by SMRHM 73 Santa Margarita Region Hydrology Model Guidance June 2013 STAGE STORAGE DISCHARGE TABLE SMRHM Example IG File Edit View Help Summary Report D m kl X ma zi A shez esoun oaa Tx Trapezoidal Pond 1 Stage Area Storage Dschrge Infilt gt ft acres acre ft cfs cfs 0 000000 0 646121 0 000000 0 000000 0 000000 0 044444 0 648177 0 028762 0 054940 0 000000 0 088889 0 650236 0 057616 0 077697 0 000000 0 133333 0 652298 0 086561 0 095159 0 000000 0 177778 0 654364 0 115598 0 109880 0 000000 0 222222 0 656433 0 144727 0 122850 0 000000 0 266667 0 658505 0 173948 0 134575 0 000000 0 311111 0 660580 0 203261 0 145358 0 000000 0 355556 0 662658 0 232666 0 155394 0 000000 0 400000 0 664740 0 262164 0 164820 0 000000 0 444444 0 666825 0 291754 0 173736 0 000000 0 488889 0 668914 0 321437 0 182215 0 000000 0 533333 0 671005 0 351213 0 190318 0 000000 0 577778 0 673100 0 381082 20 198089 0 000000 0 622222 0 675198 0 411044 0 205567 0 000000 0 666667 0 677300 0 441100 0 212782 0 000000 0 711111 0 679404 0 471249 0 219760 0 000000 0 755556 0 681512 0 501491 0 226524 0 000000 0 800000 0 683623 0 531828 0 23309
46. track of all of the individual components of the hydrologic cycle including surface runoff interflow groundwater soil moisture and evapotranspiration HSPF since its introduction in 1980 has become the industry standard for hydrologic modeling One of the major advantages of continuous simulation hydrologic modeling is the ability to accurately determine soil moisture conditions immediately prior to storm events Single event hydrologic models have to make assumptions about the antecedent soil moisture conditions assumptions which are often not accurate or appropriate This is an important distinction because antecedent soil moisture conditions play a major role in determining the amount and timing of runoff Not all continuous simulation hydrologic models handle the calculation of soil moisture conditions in the same level of detail HSPF uses a potential evapotranspiration time series to compute actual evapotranspiration each time step HSPE uses parameter values to determine the proportion of the actual evapotranspiration from interception storage upper soll layer storage lower soil zone layer storage groundwater storage and base flow Other continuous simulation hydrologic models SWMM included use a much more simplified approach to determining soil moisture Such simplified approaches do not accurately reflect the seasonal and daily variability of the actual evapotranspiration and its effects on soil moisture 2 SMRHM is based o
47. values in blue then the number of occurrences decreases and the pond successfully mitigates the additional erosive flows produced by the development If the Mitigated flow duration values in red are far to the left of the Predevelopment flow duration values in blue then the pond can be made smaller and still meet the flow duration criteria e AEAEE EP ie e li El MM Schematic PM imi Trapezoidal Pond 1 Mitigated Facility Name Facility Type Outlet 1 Outlet 2 Outlet 3 Downstream Connections 0s V Precipitation Applied to Facility Quick Pond M Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Facility Bottom Elevation ft Outlet Structure Data Riser Height ft Trapezoidal Pond 1 Automatic Pond Adjuster 0 1 min lt 210 min gt 10 mine Fast Thorough Pond Depth incl 1 ft ma e ft Pond length to width ratio 1 to 1 Pond Side Slopes 3 to1 Bottom Length 167 764867 ft Bottom Width 167 764867 ft Volume at riser head 2 171 acre ft SMRHM X Autopond Finished 4 53 F LOVV cfs Choose Outlet Structure 1 orifice amp rectangular notch Progress Pond ma malna timize Pond _ Accept pond t pond ooo Cose ttt TOE 4 10E 3 10E 2 10E 1 1 10 100 Percent Time Exceeding o Iterations 6 4 2013 9 59 AM Auto Pond goes throu
48. 0 BA 2D3 amp 13PM To export a time series dataset click on the Export Dataset box The list of available time series datasets will be shown The user can select the start and end dates for the data they want to export The time step 15 minute daily monthly yearly can also be specified If the user wants daily monthly or yearly data the user is given the choice of either selecting the maximum minimum or the sum of the 15 minute values Click the Export button 107 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM Example1 File Edit View Help Summary Report Dc EB X8 8 p e ik z S en uelut Oe Suma 2000 E olx Save As d m Save in C3 projects er EB E defaultERR txt E nfile txt My Recent Documents Desktop Start Date End Date i 374 10 01 00 00 201 1 09 30 24 00 Timestep Out Move Pu Hoy y SUM AVG y Close e Save xy Load xy xbu 1 EE y E 6 4 2013 4 14 PM The user provides a file name and the format or type of file The file type can be ASCII text comma delimited Access database recharge SWMM or WWHM Click Save to save the exported time series file 108 Santa Margarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank 109 Santa Margarita Region Hydrology Model Guidance June 2013 LID ANALYSIS SCREEN SMRHM
49. 0 x A Mw ION este NI HM hne tha mibigabion nequi selected pomi of compliance only These changes vall impact all duration analysis E A A ir Le 3 TEBAM Options can be accessed by going to View Options This will bring up the Options screen and the ability to modify the built in default duration criteria for flow duration matching and scaling factors for climate variables 114 Santa Margarita Region Hydrology Model Guidance June 2013 DURATION CRITERIA The flow duration criteria are 1 If the post development flow duration values exceed any of the predevelopment flow levels between the lower threshold 10 of the two year and five year predevelopment peak flow values then the flow duration standard has not been met 2 If the post development flow duration values exceed any of the predevelopment flow levels between the 5 year and the upper threshold 100 of the 10 year predevelopment peak flow values more than 10 percent of the time 110 Percent Threshold then the flow duration standard has not been met 3 If more than 10 percent of the flow duration levels exceed the 100 percent threshold then the flow duration standard has not been met The duration criteria in SMRHM can be modified by the user if appropriate and the local municipal permitting agency allows see NOTE below The user can conduct the duration analysis using either 1 durations based on Predevelopment flow frequency or 2 durations
50. 00 E 701 Inflow to POC 1 Mitigated Plot Hydrograph El 1000 Trapezoidal Pond 1 ALL OUTLETS Mitigated 3 Peaks 1001 Trapezoidal Pond 1 STAGE Mitigated b C Average C Volume CalendarY ear Graph Esport Copy to WDM DSN to Copy B 4 2013 3 58 PM The user can graph plot any or all time series data by selecting the Hydrograph tab The Create Graph screen is shown and the user can select the time series to plot the time interval yearly monthly daily or 15 minute and type of data peaks average or volume The following numbering system is used for the flow time series 500 599 Predevelopment flow Predevelopment scenario 700 799 Inflow to the POC Mitigated runoff entering the BMP facility 800 899 POC flow Mitigated flow exiting the BMP facility The selected time series are shown To graph the selected time series the user clicks on the Graph button 96 Santa Margarita Region Hydrology Model Guidance June 2013 a Example Clear Creek Solutions SMRHM Example1 6 4 2013 il aly Zoom Set Annual Max Peak Values go Flow cfs o p 1975 1980 2000 2005 2010 _ 501 POC 1 Predeveloped tow 801 POC 1 Magated fow The hydrograph shows the yearly maximum peak flow values for each time series for the entire simulation period in this example from 1974 through 2010 The graph can be either saved or printed 97 Santa Margarita Region Hydrology Model Gui
51. 1 0 000000 0 844444 0 685738 0 562258 0 239478 0 000000 0 888889 0 687856 0 592782 0 245699 0 000000 0 933333 0 689977 0 623401 0 251767 0 000000 0 977778 0 692101 0 654113 0 257692 0 000000 1 022222 0 694228 0 684921 0 263483 0 000000 1 066667 0 696359 0 715823 0 269150 0 000000 1 111111 0 698493 0 746819 0 274700 0 000000 1 155556 0 700630 0 777911 0 280140 0 000000 Move Elemenis 1 200000 0 702771 0 809098 0 285477 0 000000 A 1 244444 0 704915 0 840380 0 290715 0 000000 Ey 1 288889 0 707062 0 871757 0 295861 0 000000 Y 1 333333 0 709212 0 903230 0 300919 0 000000 seas Lond Bees 1 377778 0 711366 0 934798 0 305893 0 000000 1 422222 0 713523 0 966462 0 310788 0 000000 1 466667 0 715683 0 998222 0 315606 0 000000 v Bad Ho M1 51111i 0 717846 1 030079 0 320353 0 000000 6 4 2013 13 17 PM The stage storage discharge table hydraulically represents any facility that requires stormwater routing The table is automatically generated by SMRHM when the user inputs storage facility dimensions and outlet structure information SMRHM generates 91 lines of stage surface area storage surface discharge and infiltration values starting at a stage value of zero facility bottom height and increasing in equal increments to the maximum stage value facility effective depth When the user or SMRHM changes a facility dimension for example bottom length or an orifice diameter or height the model immediately recalculates the stage storag
52. 1 D less 1 4 NTS 6 Provide at least one 3 X 080 inches support bracket anchored to concrete wall maximum 3 0 vertical spacing 7 Locate elbow restrictor s as necessary to provide minimum clearance as shown 8 Locate additional ladder rungs in structures used as access to tanks or vaults to allow access when catch basin is filled with water Figure 3 17 Flow Restrictor TEE 64 Santa Margarita Region Hydrology Model Guidance June 2013 removable water light coupling i i NOTES min outlet capacity 100 year developed peak flow metal parts corrosion resistant steat parts to elbow with 6 max catch basin type 2 minimum 72 diameter sa ELBOW RESTRICTOR DETAIL orifices sized and located as required with NTS lowest orifice a minimum of 2 from base Figure 3 18 Flow Restrictor Baffle Riser protection structures PIENE courtesy of Washington State Department of Ecology INFILTRATION Infiltration of stormwater runoff is a recommended solution if certain conditions are met These conditions include a soils report testing eroundwater protection pre settling and appropriate construction techniques NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor The user clicks on the Infiltration option arrow to change infiltration from NO to YE
53. 10 and 25 year frequency values are on the right Flow frequency calculations are based on selecting partial duration flow values and ranking them by their Cunnane Plotting Position The Cunnane Plotting Position formula is Tr N a m b where Tr return period years m rank largest event m 1 N number of years a 0 2 b 0 4 Probability 1 Tr The return period value Tr is used in SMRHM to determine the 2 year 5 year 10 year and 25 year peak flow values If necessary the 2 year 5 year 10 year and 25 year values are interpolated from the Tr values generated by Cunnane 94 Santa Margarita Region Hydrology Model Guidance June 2013 DRAWDOWN SMRHM Example1 File Edit View Help Summary Report D c B X afa ABSHES Oe SO BEE D OGD Analysis Drawdown Analysis Select analysis for 1001 Trapezoidal Pond 1 STAGE Mitigated Pond Trapezoidal Pond 1 Drain Time days Stage feet Percent of Total Run Time 528435 239943 172922 ZA Max Stage 3 408461 Drawdown Time dd hh mm ss 01 20 33 08 Pond drains in less than 4 days Durations Flow Frequency Drawdown LID BMP Sizing Analyze datasets 1 ELSINORE EVAP Duration Bounds 2 Temecula Valley Minimum Maximum 22 IRRIGATION IN INCHES Bal 2 501 POC 1 Predeveloped flow 701 Inflow to POC 1 Mitigated 801 POC 1 Mitigated flow Seasonal Durations mm dd 1000 Trapezoidal Pond 1 ALL OUTLETS Mitigate 1001 Trapezoidal Pond 1 STAGE Mit
54. 13 45 C D Urban Flat 0 5 142 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 Table 2 SMRHM HSPF Pervious Parameter Values Part I 4 4 CEN Bo A BO 6 poo ooo Bo A jp o CENE e A ICI 15 11 B20 poso Boo p15 20 997 16 1 11 g880 po3o 200 p25 120 Q997 17 o 00 X 0800 40 05 120 p980 18 1 RM70 0060 pso pio 20 0 980 19 1 g40 Q045 g00 X p15 120 poso 20 gio 0035 oo p25 120 980 21 500 pozo oo pos 120 22 a ZN 25 S 26 S TM RN 290 BO Bt P 1 2 3 5 7 10 11 12 13 1 15 16 17 18 19 20 21 9 0 22 23 2 25 26 27 28 29 30 31 4 35 M20 0 035 B00 b15 45 460 143 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 46 4 20 0 030 350 0 10 3 00 0 995 LZSN Lower Zone Storage Nominal inches INFILT Infiltration inches per hour LSUR Length of surface flow path feet SLSUR Slope of surface flow path feet feet KVARY Variable groundwater recession AGWRC Active Groundwater Recession Constant per day 144 Appendix A Table 3 SMRHM HSPF Pervious Parameter Values Part II PERLND No INFEXP_ NFILD DEEPFR BASETP AGWETP OOOO po pos O00 2 Roo oo poo pos poo O em o pos po 4 m go po 200 po boe bo 0 02 200 Bo poz fo 2 00 p00 0 02 0 2 00 p00 0 02 0 0 poo poo poz po 2 00 0 02 0 02 2 00
55. 1H from L for each side of the notch weir 63 Santa Margarita Region Hydrology Model Guidance June 2013 The physical configuration of the outlet structure should include protection for the riser and orifices to prevent clogging of the outlet from debris or sediment Various outlet configurations are shown below They have been reproduced from Volume III of the Stormwater Management Manual for Western Washington which has more information on the subject removable watertight coupling or flange plate welded to elbow with orifice as specified eibow restrictor see detail j handholds steps or ELBOW RESTRICTOR DETAIL sce Now s ladde NTS invert and elevation shear gate with control rod for cleanout drain 1 section ot pipe attached by gasketed band to allow removal restrictor plate Ai with orifice diameter as MR specified not needed if SECTION A A ISOMETRIC NTS NTS NOTES 1 Use a minimum of a 54 diameter type 2 catch basin 2 Outlet Capacity 100 Year developed peak flow 3 Metal Parts Corrosion resistant Non Galvanized parts perferred Galvanized pipe parts to have asphalt treatment 1 4 Frame and ladder or steps offset so A Cleanout gate is visible from top B Climb down space is clear of riser and cleanout gate C Frame is clear of curb 5 If metal outiet pipe connects to cement concrete pipe outlet pipe to have smooth PLAN VIEW O D equal to concrete pipe
56. 2013 For the three amended soil material layers the user inputs Layer Thickness feet depth of amended soil Type of amended soil 24 different soil types are included the user can also create their own soil type using the Edit Soil Type button NOTE Amended soil layers 2 and 3 are optional Infiltration to the native soil can be turned on by setting Native Infiltration to YES The parameters for native soil infiltration are Measured Infiltration Rate inches per hour infiltration rate of the native soil Infiltration Reduction Factor between 0 and 1 1 Native soil infiltration rate safety factor see page 69 Use Wetted Surface Area sidewalls YES or NO YES allows infiltration to the native soil through the sidewalls of the swale otherwise all infiltration 1s through the bottom only If infiltration 1s used then the user should consult the Infiltration discussion on page 69 NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor The user has two bioretention surface outlet configuration choices 1 Vertical Orifice Overflow or 2 Riser Outlet Structure 79 Santa Margarita Region Hydrology Model Guidance June 2013 Santa Margarita Region Hydrology Model psHEE Osh aa lt sl Bio Swale 1 Mitigated ed Facility Name Downstream Connection Facilit
57. 4 Pass Peroent Time Exceeding 399 454 13 Pass 560 417 78 Fass 328 3858 73 Pass 502 354 70 Fass 464 326 70 Pass 430 258 66 Fass 399 265 66 Pass 365 245 67 Pass 339 228 57 Pass 317 207 65 Fass 284 187 65 Pass z68 175 65 Fass 258 16 62 Pass 241 145 61 Fass aad 139 amp 2 Pass 208 125 62 Fass 191 116 50 Fass 184 106 57 Faas 172 36 55 Pass i64 BB 53 Pass 152 TT 50 Fass FLOVvwv cfs 10 3 102 101 NET q002AM To review the flow duration analysis at the point of compliance select the POC 1 tab at the bottom and make sure that both the 501 POC 1 Predevelopment flow and 801 POC 1 Developed flow are highlighted 24 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM File Edit View Help Summary Report Dc EB X8 8 pmaeumsUsows5umMx oo The Facility PASSED ll 801 POC 1 Mitigated flow x The Facility PASSED Flow cfs Predev Mit Percentage Pass Fail 3981 1854 1854 100 Pass 4816 1591 1493 93 Pass 5650 1431 1256 87 Pass 6484 1287 1094 85 Pass 7318 1156 972 84 Pass 8153 1049 878 83 Pass 8987 963 793 82 Pass 9821 888 704 79 Pass 0655 822 634 77 Pass 1489 753 577 76 Pass 2324 700 517 23 Pass 3158 649 482 74 Pass 3992 599 454 75 Pass 4826 560 417 74 Pass 5660 529 389 73 Pass 6495 502 354 70 Pass FL OVV cfs 0 40 ns 10E 5 10E 4 10E 3 10E 2 10E 1 Percent Time Exceeding Durations Drawdown Hydrograph LID BMP Sizing Analyze datasets
58. 5 65 0 55 0 50 25 p40 po X Q40 P45 p 50 26 p 40 0 40 X 040 X 045 XQ50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 27 40 040 po X Q45 X Q50 0 55 0 55 0 55 0 55 0 55 0 45 0 40 28 1 p40 p40 040 Q45 050 055 055 0 55 0 55 055 45 p40 29 050 P 5so 050 0 60 65 0 65 0 65 0 65 0 65 0 65 0 55 0 50 0 50 050 050 p 60 65 P 65 P 65 065 D 65 0 65 0 55 P 50 154 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 0 50 0 50 0 50 0 60 0 65 gt 65 E 65 65 65 E 65 55 gt 50 p bsa oso bso beo pes pss pes nes pss pes pss ps is pe pe beo bro 075 prs pz prs br 075 be peo 34 peo peo peo p70 075 0 75 p75 075 075 075 65 peo peo peo xum p75 075 qne o5 075 Ru pe mm s oeo peo peo pro 075 pre prs Drs pre p75 65 peo 575050 bso peo bes pes pes pes pes bes bss bso 88 Q 50 X 0 50 X 0 50 p6o_ pes X Q e5 0 65 0 65 0 65 0 65 0 55 50 39 qo50 X 0 50 X 0 50 P 60 pes X Q e5 0 65 0 65 0 65 p65 0 55 0 50 40 1 p50 X Q050 p50 X60 065 0 65 0 65 0 65 65 pP65 55 Q50 45 50 0 50 X 0 50 X Q0 pes 0 65 0 65 0 65 0 65 0 65 0 55 0 50 46 1 p50 X p50 Q5o p60 065 0 65 p65 0 65 65 065 0 55 p50 47 pso 0 50 X 0 50 peo Q5 0 65 0 65 0 65 0 65 0 65 0 55 0 50 48 1 p 50 50 p50 60 65 65 65 P 65 65 0 65 055 p50 155 Appendix A Santa Ma
59. 5 200 045 geeTabe7 21 see Table6 0 90 p 30 300 70 see Table7 23 seeTable6_ 050 030 160 0 40 see Table 24 ee Tables 0 40 0 30 p 60 p35 seeTable7 28 see Tables 030 025 060 0 35 geeTabe7 32 see Tables 030 025 060 030 seeTable7 35 see Table6 60 035 100 245 geeTabe7 37 see Tables 090 030 200 070 geeTabe7 147 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 46 see Table 6 0 50 0 25 0 70 0 35 see Table 7 CEPSC Interception storage inches UZSN Upper Zone Storage Nominal inches NSUR Surface roughness Manning s n INTFW Interflow index IRC Interflow Recession Constant per day LZETP Lower Zone Evapotranspiration fraction 148 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 Table 5 SMRHM HSPF Pervious Parameter Values Part VI PERLND No CEPS SURS UzS FWS zs AGWS GWVS p00 0 00 por poo so bso bo 2 poo poo poi poo ps5o pao pol 3 pom X po poi poo ps5o pao pol 4 1 poo poo pot po ps5o pao Pot 5 po poo poi poo ps5o pao pol 6 111 poo Qoo pot po ps5o p3o pot 7 po poo poi poo ps5o pao pol Boo 11 po poo poi poo ps5o pao pol 9 1 pom poo poi poo ps5o pao pol 10 poo poo pot po ps5o pao Qo o O po X po poi poo ps5o pao fo 12 poo poo pot po ps5o p3o Pot 13 1 po poo pot poo 50 150 pio 14 poo po poi poo 350 150 pio
60. ALBASINELEMENT Pervious artos do ias 43 LATERAL I BASIN ELEMENT Impervious eene eene nennen nennen 44 TRAPEZOIDAL POND ELEMENT esos ionen 45 NVAULCELEMEN ui A ue De Dedi e bug 49 TANK ELEMEN s ER 2 IRREGULAR PONDEREMENT sai esi Sn irm 53 PONDENDINDEBIEAS Puso oae derat T rette 54 GRAVEL TRENCH BED ELEMENT 00 ii ade teal eect oan ee e dos 56 SAND FILTER ELEMENT 525i rtr tono dali eus ve ToU EU EUREN SUR oa 58 OUTLEFSTRUCTURE CONFIGURATIONS usada 60 INPIETRATI N serana a td id ds 66 AUTO POND Pm 67 CHANNEL ELEMENT asa 69 LELOWSGPELIETER ELEMENT iio 71 ROLE SERIES ELEMENT optant nint bu iaa tas 73 STAGE STORAGE DISCHARGE TABLE nena 74 STADE PLEMENT cc ER EE E 75 BIORE TENTION ELE VEN o o EN od eae aa use SAN re be udedits 78 POINT OC OER LINO p 85 CONNECTING ELEMEN VS 3 2 1 57 1 paid 87 ANALYSIS SCREEN Mc 90 PLOW DURATION nn TE 92 EXON PRECUENEY patatas 94 DRAWDOWN Deni cacao 95 HY DROGRAP EIS ta UU Me uM a Ulo es tubo UN eL uU lb aud 96 ED BMP SI ZING M 97 REPORTS SCREEN serio n T TA 104 Santa Margarita Region Hydrology Model Guidance June 2013 TOOLS CREEN iris 106 LIDRANALI SIS SCREEN io 110 BIS NT 114 DURATION CRITERIA 5 2 13 22 ote N US 115 SEALING EACTORS M 116 TIPS AND TRICKS FOR LID PRACTICES AND FACILITIES 118 INFILTRATION BAN PON Dias 119 INFILTRATION TRENG tr id 122 LERME ADELA EME do
61. Available Pervious Acres ajr AfseRPaBSr AFseuModE WR M AFoea edi taj Je NETA M Asmera Je M aema ESTE 8 M Koen Foie M AGressMed10 5 gt Meade ira R M Atep Spam o BFeesFlupsx i M Faena 0 cjr Efron p E PervicusT otal imperious Total DMA Total Face fp Acre Pece egeleci Zero Interflows 7 Show Only Selected RosdsMedi510 Po is BoadiVen teb i fo r Rasa 07 a Ir rs O Y EA 8 SdewaksfiDSx Jo ETT 105 Sidemalks SUT 20 Parking Fisi0 5 M ParkingMods 10 O Packing Stei M Bava COS Pod amp es Jeo Select By so 5 4 2013 1256 PM The Land use Basin element represents a DMA Drainage Management Area that can have any combination of soils land cover and land slopes A DMA produces three types of runoff 1 surface runoff 2 interflow and 3 groundwater Surface runoff 1s defined as the overland flow that quickly reaches a conveyance system Surface runoff mainly comes from impervious surfaces Interflow is shallow subsurface flow produced by pervious land categories and varies based on soil characteristics and how these characteristics are altered by land development practices Groundwater 1s the subsurface flow that typically does not enter a stormwater conveyance system bu
62. D Bl 801 POC 1 Mitigated flow 2x The Facility PASSED Flow cfs Predev Mit Percentage Pass Fail 3981 1854 1854 100 Pass 4816 1591 1493 93 Pass 5650 1431 1256 87 Pass 6484 1287 1094 85 Pass 7318 1156 972 84 Pass 8153 1049 878 83 Pass 8987 963 793 82 Pass 9821 888 704 79 Pass 0655 822 634 71 Pass 1489 753 571 76 Pass 2324 700 517 73 Pass 3158 649 482 74 Pass 3992 599 454 75 Pass 4826 560 417 74 Pass 5660 529 389 73 Pass 6495 502 354 70 Pass 7329 464 326 70 Pass 8163 430 288 66 Pass 8997 399 265 66 Pass 9831 365 245 67 Pass 0666 339 228 67 Pass 1500 317 207 65 Pass 2334 284 187 65 Pass 3168 268 175 65 Pass 4002 258 162 62 Pass 4837 241 149 61 Pass 5671 222 139 62 Pass 6505 208 129 62 Pass 7339 191 116 60 Pass 8173 184 106 57 Pass 9008 172 96 55 Pass 9842 164 88 53 Pass 0676 152 77 50 Pass FL OVV cfs 10E 4 10E 3 10E 2 10E 1 1 Percent Time Exceeding Durations Drawdown Hydrograph LID BMP Sizing Analyze datasets 501 POC 1 Predeveloped flow 801 POC 1 Mitigated flow All Datasets Flow Stage Precip Evap PDC 1 O 0 0 O 0 O 0 0 i 1 1 1 1 1 1 1 A li 1 1 2 2 2 2 2 2 2 2 2 2 2 2 3 6 4 2013 3 52 PM Flow duration at the point of compliance POC 1 is the most common analysis A plot of the flow duration values is shown on the left the flow values on the right The flow duration flow range 1s from the lower th
63. D elements to help reduce the facility size To evaluate the frequency and distribution of larger events in more detail use the Hydrograph tool page 99 to plot monthly peaks for several years at a time of the mitigated post project scenario to get an idea of how often the discharge that corresponds to the maximum allowed drain time would be exceeded during warmer months when mosquito development times are shortest 164 Appendix C Santa Margarita Region Hydrology Model Guidance June 2013 Treatment Credit Use the applicable design criteria to determine the minimum treatment volume for the post project scenario Look at the pond volume representing a 2 day drawdown in the SMRHM s flow duration drawdown table If this 1s larger than the calculated treatment volume no further treatment design is needed If the pond volume is less than the treatment volume or always drains in less than 2 days most or all of the water quality criteria may still be met 1f the combination of infiltration loss and detainment captures 80 of the runoff from the site Infiltration loss for each pond stage 1s shown in the Stage Storage Discharge table accessed by selecting the Open Table option at the bottom of the main Pond screen Flood Control Detention Local flood control design criteria must be obtained from the appropriate agency as well as any other policies or restrictions that may apply to drainage design A single design storm event can be
64. GE Mitigated Duration Bounds 0 01 Minimum 2 Maximum Seasonal Durations mm dd StatDate _ Al Datasets Flow Stage Precip Evap_ POC1 EndDate 674 2013 10 03 AM Select the pond you want to analyze for drawdown retention time in this example there 1s only one pond Trapezoidal Pond 1 by clicking on the dataset and highlighting it 28 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM Fie Edt Wew Hep Summary Report Dae Da ASHE Our Sane lie Se Drawdown Analysis CBE Trapezcedsi Pond 1 STAGE Mitigated Trapezoidal Pond 1 5 Seasonal Duration mm dd StatDate Eao 5 4 2013 10 06 AM Click on the Analyze Stage button and the computed pond stages pond water depths are summarized and reported in terms of drain retention time in days For this example the maximum stage computed during the entire 30 50 year simulation period is 3 40 feet This maximum stage has a drawdown time of 1 day 20 hours 33 minutes and 8 seconds Ponds may have drain times in excess of the allowed maximum of hours This can occur when a pond has a small bottom orifice If this 1s not acceptable then the user needs to change the pond outlet configuration manually run the Mitigated scenario and repeat the analyze stage computations A situation may occur where it is not possible to have both an acceptable pond drawdown retention time and meet th
65. HSPF Special Actions is used to check the swale soil capacity to determine the appropriate routing option A bioretention facility is a swale in which the native soils have been excavated and replaced with amended soil At the downstream end of the swale a weir or riser controls the surface discharge from the swale and detains runoff encouraging it to infiltrate into the amended soil Infiltration from the amended soil to the native soil is also possible depending on the properties of the native soil Swales can include an underdrain pipe The amended soil placed in the swale is assumed to have storage capacity equal to its porosity and volume Runoff infiltrates from the surface of the swale to the amended soil at an infiltration rate set by the user The infiltration rate cannot exceed the available storage capacity of the amended soil The available storage capacity 1s determined each time step by HSPF Special Actions Once the amended soil is saturated then water has the opportunity to infiltrate into the underlying native soil at the native soil s infiltration rate The native soil infiltration 1s input by the user and is assumed to be constant throughout the year Inflow to the swale can exceed the amended soil infiltration rate When this occurs the extra water ponds on the surface of the swale The extra water can then infiltrate into the soil during the next time step or can flow out of the swale through its surface outlet if the ponding e
66. Margarita Region Hydrology Model Guidance June 2013 In SMRHM the extended detention basin is represented by treatment train connecting a trapezoidal pond or irregular pond element to a gravel trench element to a sand filter element in that order There 1s also the option of creating the extended detention basin s stage storage discharge table outside of SMRHM and inputting 1t as a SSD Table element File Edit View Help Summary Report ES a nasusalOssamzjoos a Filter Drain Mitigated Facility Name Filter Drain Qutlet 1 Qutlet 2 Qutlet 3 Downstream Connections Facility Type Sand Filter v Precipitation Applied to Facility Quick Filter Moon qne Facilitv Dimension Diagram A NA p A 3 Qutlet Structure Data Bottom Width ft Riser Height ft las Riser Diameter in 12 Riser Type Flat E BL Bottom Side Slope HAY fi Notch Type 4 Right Side Slope HZ Top Side Slope H Infiltration ves Orifice Diameter Height Hydraulic Conductivity in hr hs Number in ft 1 fo db Filter material depth ft 3 ES 2 D Jl oo a Total Volume Filtrated ac ft 54 554 3 o H lo Total Volume Through Riser ac ft 58 873 Total Volume ac ft 113 427 Filter Storage Volume at Riser Head ac ft 204 E Filter Drain Percent Filtered 48 1 Show Filter Table OpenTable Al 1 Size Infiltration Basin Initial S
67. S This activates the infiltration input options measured infiltration rate infiltration reduction factor and whether or not to allow infiltration through the wetted sideslopes walls Santa Margarita Region Hydrology Model Guidance June 2013 fa Irapezoidal Pond 1 Mitigated Trapezokdal Pond 1 Pond 1 Outlet 1 Downstream Connections IV Precipitation Applked to Facility IV Evaporation Appled lo Facility Facility Dimensions Facility Bottom Elevation H Bottom Length A Bottom Width H Effective Depth It Left Side Slope HA Bottom Side Slope HY Richie ETA op Side Slope HV Infiltration higasured Initiation Rate mu Redi N Bn Use Wetted Surface Area sdewal a No Total Volume brdltrated act Total Volume Thecugh Rise lach 0 Total Volume Though Facity lact 0 00 Percent Infdtiated 0 Size Infiltration Pond Target 100 Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation It Cveto Elevation ft Facility Type Trapezoidal Pond Outlet 2 Outlet 3 Auto Pond Quick Pond Facility Dimension Diagram Outlet Structure Data Riser Hegi fp yH Riser Diameter fin go H Riser Type Fiat Notch Type Orifice Diameter Height umber im ft ih Ab sej Sp a gt pio Pond Volume st Riser Head fact ij Show Pond Table Openlabe Initial Stage If fo Downstream Connection fo Iterati
68. Santa Margarita Region Hydrology Model Guidance Document Clear Creek Solutions Inc www clearcreeksolutions com June 2013 Santa Margarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank Santa Margarita Region Hydrology Model Guidance June 2013 To download the Santa Margarita Region Hydrology Model and the electronic version of this document please go to www clearcreeksolutions com downloads If you have questions about SMRHM or its use please contact Clear Creek Solutions Inc 360 943 0304 8 AM 5 PM Pacific time 11 Santa Margarita Region Hydrology Model Guidance June 2013 End User License Agreement End User Software License Agreement Agreement By clicking on the Accept Button when installing the Santa Margarita Region Hydrology Model SMRHM Software or by using the Santa Margarita Region Hydrology Model Software following installation you your employer client and associates collectively End User are consenting to be bound by the following terms and conditions If you or User do not desire to be bound by the following conditions click the Decline Button and do not continue the installation process or use of the Santa Margarita Region Hydrology Model Software The Santa Margarita Region Hydrology Model Software is being provided to End User pursuant to a sublicense of a governmental licensee of Clear Creek Solutions Inc Pursuant to the terms and c
69. TTED CURE PARKING OR DRIVE AISLE d Y RSS FEV WV r 1 SMEJ 18 36 Meta ri Y tno tne NE MATURE VEGETATION 277 2 ENGINEERED fet be ste em e tL Lut L AND SET UREE cas SOIL MEDIA IC Tes a ko rere A dL ba em XM is PERFORATED PIPE TIE SUBDRAIN INTO INLET RETAINING WALL TYPE 1A PER CALTRANS STANDARD B3 3 OR ENGINEERED ALTERNATIVE BASED ON GEOTECHNICAL PARAMETERS Figure courtesy of Riverside County Flood Control and Water Conservation District Bioretention standard design allows stormwater to enter the bioretention facility above ground and then infiltrate through the mulch layer engineered soil media and gravel storage layers before exiting through a discharge pipe For the purpose of flow control the discharge from the pipe should not exceed the predevelopment discharge from the project site for the flow duration range specified by the local jurisdiction In SMRHM the bioretention standard design is represented by the bioretention element 128 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM File Edit View Zoom Help eS AASEN PRAH R DOD MM Schematic TB 8 Bio Swale 1 Mitigated Predeveloped LITE Facility Name Run Scenario fiel Outlet 1 Outlet 2 Outlet 3 Drainage Elements Flow Connections Downstream Connection pp Facility Type l Use simple swale Default Swale iv Underdrain Used Underdrain Diameter ft 05 O
70. Underdram ac ft Total Outflow act Vertical Orice Ovestom H Qutlet Configuration Data Vertical Onfice diameter m Vertical Onfice Elevation in Width of overoad flow ff Material Layers for Swale Layer Layer2 Lager 3 Dei EJE Sod Layer 1 GRAVEL i Sol Layer 2 GRAVEL gt Scd Layer 3 GRAVEL Edit Soil Types KSat Safety Factor G Noe C2 Cd Show Swale Table Open Table H Swale Volume at Rises Head ac ft Native Infiltration No 5 4 2013 322 PM The Bioretention element represents a bioretention area or rain garden In modeling shorthand terms SMRHM has abbreviated bioretention to the default name bio swale This name can be changed by the user The bioretention element has two available outlet structure configurations 1 vertical orifice plus overflow 2 riser outlet The user is required to enter the following information about the bioretention Swale Length ft length dimension of swale surface bottom Swale Bottom Width ft width dimension of swale surface bottom Effective Total Depth ft computed by SMRHM Bottom Slope of Swale ft ft the slope of the swale length must be greater than zero Left Sideslope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical swale sides Right Sideslope ft ft H V ratio of horizontal distance to vertical O zero for vertical swale sides 78 Santa Margarita Region Hydrology Model Guidance June
71. User Clear Creek Solutions Inc and the governmental licensee or sublicensees disclaim all warranties either expressed or implied including but not limited to implied warranties of program and accompanying documentation In no event shall Clear Creek Solutions Inc or authorized representatives be liable for any damages whatsoever including without limitation to damages for loss of business profits loss of business information business interruption and the like arising out of the use of or inability to use this program even if Clear Creek Solutions Inc has been advised of the possibility of such damages Software Copyright O by Clear Creek Solutions Inc 2005 2013 AII Rights Reserved iii Santa Margarita Region Hydrology Model Guidance June 2013 FOREWORD The Santa Margarita Region Hydrology Model SMRHM is a tool for analyzing the hydromodification effects of land development projects and sizing solutions to mitigate the increased runoff from these projects This section of the guidance documentation provides background information on the definition and effects of hydromodification and relevant findings from technical analyses conducted in response to regulatory requirements It also summarizes the current Hydromodification Management Standard and general design approach for hydromodification control facilities which led to the development of the SMRHM Regulatory Context The California Regional Water Quality Control Board
72. Volume at riser head 2758 acre ft 4 5 FLOWw cfs Choose Outlet Structure 1 orifice amp rectangular notch Progress Performing Reraior Jof an ezhmabed 300 TDE 4 10E 3 10E 2 10E 1 10 100 Peroent Time Exceeding o erations 5 4 2013 3 55 AM Flow duration results are shown in the plots above The vertical axis shows the range of flows from 10 of the 2 year flow 0 40 cfs to the 10 year flow 8 66 cfs The horizontal axis is the percent of time that flows exceed a flow value Plotting positions on the horizontal axis typically range from 0 001 to 1 as explained below For the entire 30 to 50 year simulation period depending on the period of record of the precipitation station used all of the 15 minute time steps are checked to see 1f the flow for that time step 1s greater than the minimum flow duration criteria value 0 40 cfs in this example For a 50 year simulation period there are approximately 1 600 000 15 minute values to check Many of them are zero flows The 10 of the Predevelopment2 year flow value 1s typically exceeded less than 1 of the total simulation period 20 Santa Margarita Region Hydrology Model Guidance June 2013 This flow duration check is done for both the Predevelopment flows shown in blue on the screen and the Mitigated flows shown in red If all of the Mitigated flow duration values in red are to the left of the Predevelopment flow duration
73. Water Board requires stormwater programs to address the increases in runoff rate and volume from new and redevelopment projects where those increases could cause increased erosion of receiving streams Phase municipal stormwater permits in Riverside County contain requirements to develop and implement hydromodification management plans HMPs and to implement associated management measures Acknowledgements The following individuals are acknowledged for their contributions to the development of SMRHM and guidance documentation e Doug Beyerlein Joe Brascher Gary Maxfield and Shanon White of Clear Creek Solutions Inc for development of WWHM BAHM and SMRHM and preparation of the SMRHM guidance documentation e Daniel Apt and Remi Candaele of RBF Consulting a Company of Michael Baker Corporation for providing SMRHM meteorological data maps and technical specifications IV Santa Margarita Region Hydrology Model Guidance June 2013 TABLE OF CONTENTS End User license Ares ment airis iii PORE WORD H IV Resulator ONO Uni c di IV ZNXCKHOWIGdPE MENI na bent eo e idest dies Na eb ne ne bie ask IV INTRODUCTION TOS MIRE cut l OUEN STAR c EI IE EI MARI 3 MAIN SCREENS oi 35 MAP INFORMATION SCREEN iiti pee nested aeo eaae ut Fee ea doa RT Sae esaet Fete egeo 36 GENERAL PROJECT INFORMATION SCREEN nena 37 SCHEMA LIC EDITO en 39 LAND USE BASIN ELEMENT as dd 40 LATER
74. ad acu Show Pond Table Open Table Sage MN Use Tide Gate ko i tt 2m B 4 2013 259 Phi An irregular pond is any pond with a shape that differs from the rectangular top of a trapezoidal pond An irregular pond has all of the same characteristics of a trapezoidal pond but its shape must be defined by the user The Auto Pond option is not available for an irregular shaped pond Go to page 48 to find information on how to manually size an irregular pond or other HMP facility To create the shape of an irregular pond the user clicks on the Open PondPad button This allows the user to access the PondPad interface see below 53 Santa Margarita Region Hydrology Model Guidance June 2013 PondPad Interface SMRHM pusummHOowo uHo Ox S iregular Pond 1 Mitigated 1 Mitigated Facility Na Facility Type Outlet 1 Outlet 2 Downstream Connections Precpiation Applied to Faciity Evaporation Applied to Facit Facility Dimensions Outlet Structure Rises Height h o H Fises Diameter in pg H Fines Type Ra II HEP 5 4 2013 3 00 PM The PondPad interface is a grid on which the user can specify the outline of the top of the pond and the pond s sideslopes The user selects the Line button second from the top on the upper left corner of the PondPad screen Once the Line button is turned on the user moves the mou
75. am Connections p 1 Facility Type v Precipitation Applied to Facility Quick Filter M Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Qutlet Structure Data Riser Height ft 35 y Riser Diameter in 1 2 Riser Type Flat Bottom Side Slope Hv TA Right Side Slope H V Top Side Slope HV Infiltration ves Orifice Diameter Height Hydraulic Conductivity in hr hs 4 Number in ft 1 o ao Filter material depth ft 3 ote 2 oo ET Total Volume Filtrated ac ft 54 554 3 o fo r Total Volume Through Riser ac ft 58 873 i Total Volume ac ft 113427 Filter Storage Volume at Riser Head ac ft 204 Percent Filtered 48 1 Size Infiltration Basin Initial Stage ft Show Filter Table OpenTable Target Foo 4 m Move Elements ef na eae xn 1 E F m H mum dle lt 6 5 2013 2 48 PM The sand filter dimensions and parameters to adjust to represent the sand filter basin are discussed on page 61 The Riverside County Design Handbook for Low Impact Development Best Management Practices specifies the following criteria for the sand filter basin Max tributary area 25 ac Max basin depth 5 ft Max Sideslope 4 to 1 Sand filter top below bottom orifice min 4 in Sand filter top layer min 18 in of sand Sand filter bottom layer min 10 in of gravel sand filter underdrain diameter 6 in
76. artment of Ecology More information about WWHM can be found at www clearcreeksolutions com More information can be found about the Washington State Department of Ecology s stormwater management program and manual at http www ecy wa gov programs wq stormwater manual html Clear Creek Solutions is responsible for SMRHM and the SMRHM guidance documentation This guidance documentation is organized so as to provide the user an example of a standard application using SMRHM described in Quick Start followed by descriptions of the different components and options available in SMRHM The Tips and Tricks section presents some ideas of how to incorporate LID Low Impact Development facilities and practices into the SMRHM analysis Riverside County s Design Handbook for Low Impact Development Best Management Practices September 2011 has the most up to date information regarding BMP standards and should be consulted prior to the start of any SMRHM LID BMP modeling Appendices A and B provide a full list of the HSPF parameter values used in SMRHM Appendix C contains additional guidance and recommendations by the stormwater programs that have sponsored the SMRHM development Appendix D 1s a checklist for use by SMRHM project reviewers Appendix E provides additional background information on SMRHM Throughout the guidance documentation notes using this font sans serif italic alert the user to actions or design decisions for which guidance must be
77. ased on the native vegetation for the Predevelopment project area and the planned vegetation for the planned development Mitigated scenario Non urban land cover can be forest shrub and or grass In contrast the developed landscape will consist of urban vegetation lawns flowers planted shrubs and trees and is regularly irrigated Land slope is divided into flat 0 596 moderate 5 109406 steep 10 20 and very steep 220906 land slopes HSPF parameter values in SMRHM have been adjusted for the different soil land cover and land slope categories For this example we will assume that the Predevelopment land use is D soil grass vegetation moderate slope 5 10 DMA equals 10 acres Santa Margarita Region Hydrology Model Guidance June 2013 Note that the Predevelopment land use never includes man made impervious areas Existing impervious areas must be modeled as they were prior to any land use development on the project site File Edit View Help Summary Report D acl B ASHER Oe Se BE ooo le k EN ES en MM Schematic m SU DMA 1 Predeveloped INCEST Mitigated gt DMA 1 o Run DMA Name DMA 1 Scenario Surface Interflow Groundwater Flows To Dis Eten Area in Drainage Management rea Show Only Selected Available Pervious Acres Available Impervious Acres z WO EGrass Stee 10 20 o 2 Roads Flat 0 5 po Connect To Element B Grass Very S 2027 o O Roads
78. assumed to have a lid no precipitation or evaporation Auto Vault and Quick Vault work the same way as Auto Pond and Quick Pond Go to page 48 to find information on how to manually size a vault or other HMP facility NOTE Auto Vault is available only in the Mitigated scenario Vault input information Bottom Length ft Vault bottom length Bottom Width ft Vault bottom width Effective Depth ft Vault height from vault bottom to top of riser plus at least 0 5 foot extra Riser Height ft Height of overflow pipe above vault bottom Riser Diameter in Vault overflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro 49 Santa Margarita Region Hydrology Model Guidance June 2013 For a rectangular notch Notch Height ft distance from the top of the weir to the bottom of the notch Notch Width ft width of notch cannot be larger than the riser circumference For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 69 Use Wetted Surface Area sidewalls Yes if infiltration through the vault sides is allowed If infiltration is used then the user should consult the Infiltration discus
79. ater than depth NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor The infiltration trench receives precipitation on and evaporation from the trench surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should be checked 124 Santa Margarita Region Hydrology Model Guidance June 2013 PERMEABLE PAVEMENT PROPOSED BUILDING NOTE ALWAYS CONSULT YOUR GEOTECHNICAL ENGINEER FOR SITE SPECIFIC RECOMMENDATIONS Figure courtesy of Riverside County Flood Control and Water Conservation District Permeable pavement LID options include porous asphalt or concrete and grid lattice systems non concrete and paving blocks The use of any of these LID options requires that certain minimum standards and requirements are met related to subgrade geotextile material separation or bottom filter layer base material wearing layer drainage conveyance acceptance testing and surface maintenance NOTE Permeable pavement can be used in place of conventional pavement for roadways sidewalks driveways and parking lots Check with Appendix C or the local municipal permitting agency to find out under what conditions permeable pavement is allowed Permeable pavement can be represented by the permeable pavement element in SMRHM if the following three conditions are met
80. based on user defined flow values If using durations based on Predevelopment flow frequency the percent of the lower limit can be changed from the default of the 10 of the 2 year flow event to a higher or lower percent value The lower and upper flow frequency limits 2 year and 10 year also can be changed If using durations based on user defined flow values click on that option and input the lower and upper flow values The default pass fail threshold is 100 for the flows between 10 of the 2 year and 5 year flow This value cannot be changed by the user The default pass fail threshold is 110 for the flows between the 5 year and 10 year flow This value can be changed by the user The duration criteria can be changed for a single point of compliance Click on the Update button once all of the changes have been made To return to the default values click on the Restore Defaults button NOTE Any change s to the default duration criteria must be approved by the appropriate local municipal permitting agency or specified in Appendix C 115 Santa Margarita Region Hydrology Model Guidance June 2013 SCALING FACTORS Dg ig Xm EuoumE NA O Site N Address City cape cava Precip Scaling factor E EN 1 Pan Evap Fatw 1 O lock thes factor 16 5 2013 4 AM The user can change the scaling factors for precipitation minimum and maximum and pan evaporation NOTE Any change in default scaling factor
81. c 200 za 2 00 200 T zm 0 o p00 po bi h 01 a bo poo oi bs B tm po p12 s 26 200 pm be e os 200 Boo 012 po 200 poo pt po 200 B00 p36_ po 200 poo 036 pO 200 poo 36 p o 200 200 p 36 pO 3 00 200 015 p i Bo 200 O15 pa T ooN 28 290 380 0 000 a B20 B83 B40 35 0 15 s bo go pis Y 37 800 900 15 4 388 1 11 800 200 15 P 1 O go 015 pi mo FE AB Aa AB 0 15 o po pis bu so eo pas ba 145 Santa Margarita Region Hydrology Model Guidance June 2013 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 46 3 00 2 00 0 45 0 15 0 00 47 800 oo 045 045 poo 48 poo BOO p45 C 15 poo INFEXP Infiltration Exponent INFILD Infiltration ratio maximum to mean DEEPFR Fraction of groundwater to deep aquifer or inactive storage BASETP Base flow from groundwater Evapotranspiration fraction AGWETP Active Groundwater Evapotranspiration fraction 146 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 Table 4 SMRHM HSPF Pervious Parameter Values Part III PERLND No CEPSC UZSN NSUR JNTFW RC ZETP 3 S eTable6 060 035 3 00 045 geeTabe7 5 S eTable6 090 030 400 070 seeTable7 6 1 1 feeTable6 70 p 30 8 11 1 geeTabe6 040 030 180 0 35 geeTabe7 9 1 11 1 geeTabe6 080 025 400 070 geeTabe7 16 19 See Tables 060 03
82. dance June 2013 LID BMP SIZING e SMRHM Example1 w BMP Design Sl ES Santa Margarita Watershed BMP Design Volume Vg and Flow Rate Qayp Company Name Date Designed by aw County City Case No A Company Project Number Name perm A Drainage Area Number Name A Site Location Township AAA Range zz Section SSS Enter the 85th Percentile 24 hour Rainfall Depth Ds Determine the Effective Impervious Fraction Enter the Area Tributary Type of post development surface cover Effective Impervious Fraction to this Feature acres Ar Roofs Concrete or Asphalt Grouted or Gapless Paving Blocks Compacted Soil e g unpaved parking lel summary Report Dc E Ba Analysis Results Decomposed Granite Permeable Paving Blocks w Sand Filled Gap Class 2 Base Gravel or Class 2 Permeable Base Durations Drawdown Analyze datasets Flow Frequency Hydrograph Pervious Concrete Porous Asphalt Open and Porous Pavers 1 ELSINORE EVAP Duration Bounds 2 Temecula Valley 0 01 Minimum 2 Ma Turf block 501 POC 1 Predeveloped flow Natural A Soil 701 Inflow to POC 1 Mitigated 801 POC 1 Mitigated flow Seasonal Durations mm Natural B Sol 1000 Trapezoidal Pond 1 ALL OUTLETS Mitigated s 1001 Trapezoidal Pond 1 STAGE Mitigated Stet Dats Natural Soil Natural D Soil
83. dded to the DMA the land use basin element will change A small box with a bar chart graphic and a number will be shown in the lower right corner of the element This small POC box identifies this DMA as a point of compliance The number is the POC number e g POC 1 Santa Margarita Region Hydrology Model Guidance June 2013 4 Set up the Mitigated scenario Ele Edit Wew Zoom Hep DG Xm plupsumE 6wonulko o oc Ar Da x fl e 22 AM 6 4 2013 First select the Mitigated scenario tab at the top of the grid Place a land use basin element on the grid to represent the same DMA as selected in the Predevelopment scenario 10 SMRHM santa Margarita Region Hydrology Model Guidance June 2013 File Edit View Help Summary Report Dc E tete PX DMA 1 Mitigated Designate as Bypass for POC Surface Interflow raje A EI M Oe PS FILER DMA Name Flows To Area in Drainage Management Area Available Pervious Acres Trase OO Groundwater Show Only Selected Available Impervious Acres a F Roads Flat 0 5 Bees Pme 0 r BFaexsesz Jo Move Elements e mum A E lE Y PerviousT otal p Acre m Acre D Acre Impervious Total DMA Total DeselectZero Select By GO ml Er dle lt 8 4 2013 19 22AM Fo
84. destination element This action brings up the From Basin to Conveyance box that allows the user to specify which runoff components to route to the downstream element From Basin to conveyance Stormwater runoff 1s defined as surface flow plus interflow Both boxes should be checked Groundwater should not be checked for the standard land development mitigation analysis Groundwater should only be checked when there 1s observed and documented base flow occurring from the upstream basin Flow From Iw Surface Flow Interflow Groundwater After the appropriate boxes have been checked click the OK button 88 Santa Margarita Region Hydrology Model Guidance June 2013 Santa Margarita Region Hydrology Model AIRE OSA coc m x m DMA 1 Mitigated S url ace Inteaflave Groundwater Tiapezcadal Pond 1 Tiapezcedal Pond 1 Area in Drainage Management Area Show Only Selected ajr ri m RR ES Fe po ee 0 r E TP As ae rea ho r RRA fo r asmora Jo Bese O 15 FAm 8 r Siemans 0 erre 8 oe POZ ee 50 p T AG TT TT ETT pi eros Fame h raras 6 r ense 0 r a i i is Y es CS PI res F pervious Total PO Acres DMATast PO Aces S ae DerelectZero Select By G0 E E Ho l 06 4 2013 340 PM The final screen will look like the above sc
85. ditions upstream of the pond make it difficult or impossible for Auto Pond to determine which land use will be contributing runoff to the pond For these situations the pond will have to be manually sized Go to page 48 to find information on how to manually size a pond or other HMP facility NOTE If Auto Pond selects a bottom orifice diameter smaller than the smallest diameter allowed by the local municipal permitting agency then additional mitigating BMPs may be required to meet local hydromodification control requirements Please see Appendix C or consult with local municipal permitting agency for more details For manual sizing information see page 48 68 Santa Margarita Region Hydrology Model Guidance June 2013 CHANNEL ELEMENT SMRHM gBSHmE oP eee op oe T 1 f EX A Channel 1 Mitigated loped KITE Facility Name Downstream Connection Facility Type Channel Usex Sechons Quick Channel Facility Dimension Diagram Clean and Staigh 0 030 Channel Dimensions Browse for file General Channel Data Channel Bottom vadth H Channel Length H Manning n cost hcsent Siope of Changed FT Let Side Spe HM 5 Right Se Shoe tW 5 Mac mum Channel Depth ft Infiltration No Channel 1 l Show Channel Table Open Tabe Save xy Load xy i x Ea mem The Channel elem
86. drological Simulation Program Fortran User s Manual for Version 12 AQUA TERRA Consultants Mountain View CA 140 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 Table 1 SMRHM Pervious Land Types TA re o E k dus hou E 10 res Steep 10 20 4 1 hA X Forest J go Se gt 20 o FR Rh Ea usus E 10 7 A hub Steep t0 20 8 CUA O gSmb very Steer gt 20 ooo A os SMS E E o gt oo no E 10 DEM GEM NN Steep 10 20 q E Steet gt 20 h utm at ja A ban Moderate E 10 is ho n Steep 10 20 ie A Urban vey Steet gt 20 mo o B Forest Flat 0 5 18 Forest Moderat Z 0 19 B _ Forest Steep 10 20 20 Bp X Fores X VerySteep gt 20 21 J4B JHShub Flat 0 5 2 DB gShub X Moderate 5 10 03 B hub Steep 10 20 244 O B Shwe go Sisep gt 20 SS MA IA z a eo a E 10 op ie Steep 10 20 EA go Seep gt 20 B Urban Flat 0 5 Bj Urban Teens E 1096 B Urban Steep 10 20 B Urban X VerSteep gt 20 CD F E CO Flat 0 596 Moderate 5 10 Steep 10 20 Very Steep gt 20 Flat 0 5 Moderate 5 10 Steep 10 20 Very Steep gt 20 Flat 0 5 AM 5 E Very Steep 620 CO O SS J E 0 Eom o o OS AS NO 00 N 141 Appendix A Santa Margarita Region Hydrology Model Guidance June 20
87. ducted for 100 flow levels between the lower limit and the upper limit The model counts the number of 15 minute intervals that predevelopment flows exceed each of the flow levels during the entire simulation period The model does the same analysis for the post project mitigated flows Low impact development LID best management practices BMPs have been recognized as opportunities to reduce and or eliminate stormwater runoff at the source before it becomes a problem They include compost amended soils bioretention permeable pavement green roofs rain gardens and vegetated swales All of these approaches reduce stormwater runoff SMRHM can be used to determine the magnitude of the reduction from each of these practices and the amount of stormwater detention storage still required to meet HMP requirements 3 The actual flood frequency calculations are made using the Cunnane flood frequency equation 171 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 Bioretention Modeling Methodology The bioretention element is also known as a landscape swale or rain garden The SMRHM bioretention element is a special conveyance feature with unique characteristics The element uses the HSPF hydraulic algorithms to route runoff but the HSPF routing 1s modified to represent the two different flow paths that runoff can take The routing is dependent on the inflow to the swale and the swale soil capacity to absorb additional runoff
88. e H V b Notch Type Right Side Slope HV o Material Layers for Trench Bed J Layer 1 Thickness ft Orifice Diameter Height Layer 1 porosity 0 1 Number in ft Layer 2 Thickness ft p 1 o 4h Layer 2 porosity 0 1 po 2 o 40 ay Layer 3 Thickness ft o 3h Al Layer 3 porosity 0 1 o Infiltration ves mel Trench Volume at Riser Head ac ft 141 Measured Infiltration Rate in hr 12 EE Reduction Factor infilt factor E E Show Trench pen Table Use Wetted Surface Area sidewalls IN O a Initial Stage ft Dess Total Volume Infiltrated ac ft 294 833 Total Volume Through Facility ac ft 365 244 Total Volume Through Riser ac ft 70 406 Percent Infiltrated 80 72 Size Infiltration Trench Target 100 4 r Move Elements a oy Ne km zn n lt 6 5 2013 8 54 AM The gravel trench bed dimensions and parameters to adjust to represent an infiltration trench are Trench Length ft Infiltration trench length Trench Bottom Width ft Infiltration trench width Effective Total Depth ft Infiltration trench height from bottom of trench to top of riser plus at least 0 5 feet extra Bottom Slope of Trench ft ft Must be non zero Left Sideslope ft ft O zero for vertical infiltration trench sides Right Sideslope ft ft O zero for vertical infiltration trench sides Infiltration Rate in hr Infiltration trench soil infiltration rate Layer Thickness ft Infiltratio
89. e discharge table The user can input to SMRHM a stage storage discharge table created outside of SMRHM To use a stage storage discharge table created out of SMRHM the SSD Table element is required See the SSD Table element description below for more information on how to load such a table to SMRHM program 74 Santa Margarita Region Hydrology Model Guidance June 2013 SSD TABLE ELEMENT Santa Margarita Region Hydrology Model ASAE AAA Manual Infitration Load File Bremse Add Laye Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft D DeownsteamConnecion Overflow Elevation ff j Meretons b Intitial Stage ft la 644 2013 3 19 PM The SSD Table is a stage storage discharge table externally produced by the user and is identical in format to the stage storage discharge tables generated internally by SMRHM for ponds vaults tanks channels etc The easiest way to create a SSD Table outside of SMRHM is to use a spreadsheet with a separate column for stage surface area storage and discharge in that order Save the spreadsheet file as a comma delimited file A text file can also be created if more convenient The SSD Table must use the following units Stage feet Surface Area acres Storage acre feet Discharge cubic feet per second cf
90. e fi mua aroundwater Selected rvious Acres V Units of Inches Water Balance Chart Close Units of Acre Ft e DMA Total Acres Deselect Zero Select By GO 164 2013 14 40 PM _ Click on the Compute LID Base Data button to generate the LID analysis data and summarize the surface runoff interflow groundwater precipitation evaporation and total runoff for all of the basins The results will be shown for each basin in terms of its POC For DMA 1 1 acre of A Grass Moderate slope the distribution of the precipitation 1s Surface runoff 0 242 inches per year Interflow 2 133 inches per year Groundwater 2 089 inches per year Evaporation 11 419 inches per year The sum of the surface runoff interflow groundwater evaporation equals 15 883 inches per year The precipitation at this site equals 15 910 inches per year The difference 1s because 2 of the groundwater goes to deep or inactive groundwater and is not included in the LID table To look at the other DMAs click on the Select POC To arrow and select the DMA of interest The LID analysis results can be presented in terms of either inches per year or acre feet per year by checking the appropriate box in the lower right portion of the LID analysis screen 112 Santa Margarita Region Hydrology Model Guidance June 2013 To compare the different POCs side by side as bar charts click on the Water Balance Chart SMRHM Eje Edt Mew Hel
91. e Data oan pas IE Sed Layer GRAVEL Sod Layer 2 GRAVEL Orifice Diameter Height Sod Layer 3 GRAVEL E Number in ft ras zem ib db Edit Soil Types H E ip do si KSat Safety Factor 3 He amp None 02 CA Show Swale Table Open Table Swale Volume sl Rue Head act Native Infiltration NO E Fa P d v 5 4 2013 3 33 PM There is a simple swale option It is computationally much faster than the standard bioretention Before using the simple swale option read the note on the screen and the information below to understand the limitations of the simple swale The standard bioretention routine uses HSPF Special Actions to check the available amended soil storage and compares it with the inflow rate Because of the check done by HSPF Special Actions simulations using bioretention take much longer than simulations not using bioretention Simulations that normally take only seconds may take multiple minutes when one or more bioretention facilities are added depending on the computational speed of the computer used One solution to this problem is to use the simple swale option check the Use Simple Swale box The simple swale does not include HSPF Special Actions It is less accurate than the standard swale Tests have shown that the simple swale option should only be used when the swale area and volume 1s relatively small compared to the contributing basin area If in doub
92. e Outlet B 1 orifice amp rectangular notch z Overflow Elevation ff 6 herations 5 4 2013 32 M A trapezoidal stormwater pond can be sized either manually or automatically using the Auto Pond feature For this example Auto Pond will be used Go to page 48 to find more information about how to manually size a stormwater pond detention basin or other HMP facility Click on the Auto Pond button and the Auto Pond screen will appear The user can set the pond depth default 4 feet pond length to width ratio default 1 to 1 pond sideslopes default 3 to 1 and the outlet structure configuration default 1 orifice and riser with rectangular notch weir 18 Santa Margarita Region Hydrology Model Guidance June 2013 To optimize the pond design and create the smallest pond possible move the Automatic Pond Adjuster pointer from the left to the right 4 Trapezoidal Pond 1 eg Automatic Pond Adjuster 0 1 min lt 2 10 min gt 10 mine MM Predeveloped MM Mitigated Fast Thorough Pond Depth incl 1 ft freeboard ft Pond length to width ratio 1 to 1 Pond Side Slopes I to 1 Bottom Length ft Bottom Width D jit Volume at riser head Choose Outlet Structure 1 orifice amp rectangular notch Progress The pond does not yet have any dimensions Click the Create Pond button to create initial pond dimensions which will be the starting point for Auto Pond s
93. e flow duration criteria NOTE See Appendix C or the local municipal permitting agency for an overview of other requirements that may apply regarding drawdown time and suggestions for addressing situations where it is not possible to meet all drawdown retention time guidelines and also meet the flow duration criteria The guidance documentation assumes that the flow duration criteria take precedence unless the user is instructed otherwise by the local municipal permitting agency 29 Santa Margarita Region Hydrology Model Guidance June 2013 7 Produce report SMR E XT in Sur mary Report nem sy gaeummHewsamuccc EIER MM chemati mI s apezol Pan Mitipate E d bliligated Outlet Z Outlet 3 Downstream Connections I Precision Agp o aci a e on V Evaporation Applied to Facity Fact Dimension Diagram SH eight Hi pa ype ET Type Rectanada Height ti 07259 wahi hs Diameter Height Se a m 0 bo ih o Ho m ee 2471 zgo Table pen Tide Gate Elevation ff o Downstream Connection z Overflow Elevation If D ermis LN lenan O 1008AM Click on the Reports tool bar button fourth from the left to generate a project report with all of the project information and results The project report can be generated as either a Microsoft Word file or a PDF file 30 Santa Margarita Region Hydrology Model Guidance June 2013
94. e grid 0 1s the upper left corner Grid Y Vertical location of the mouse pointer on the grid 0 is the upper left corner Area Top area of the pond either in square feet or acres Slope Sideslope of the selected line side of the pond 55 Santa Margarita Region Hydrology Model Guidance June 2013 GRAVEL TRENCH BED ELEMENT SMRHM Eje dt bew Hep ummary Report MM Schematic j OX si Gravel Trench Bed 1 Mitigated x Facility Name Gravel Trench Bed 1 Outlet 1 pjueummSEoOuy5suHo Gravel Trench Bed Quick Trench Facility Dimension Diagram Outlet Structure Data Rise Height t Dm lt A Riser Diameter fin fo l RmeTye fia Motch Type Material Layers for Trench Bed Layer 1 Thickness M o Orifice Diameter Height Humber in It vp sho fuo a lt 3 p Ho Trench Volume at Aite Head ac R 000 Layer 3 Thickness M Layer 3 porosity 0 1 Infiltration Show Trench Open Table rial Stage 1 p O O am 5 4 2013 301 PM The gravel trench bed is used to spread and infiltrate runoff but also can have one or more surface outlets represented by an outlet structure with a riser and multiple orifices The user specifies the trench length bottom width total depth bottom slope and left and right sideslopes The material layers represent the gravel rock layers and their design characteristics thickness and p
95. e hydraulic conductivity inches per hour For sand filters K 1 0 in hr Sand is the default medium If another filtration material is used then the design engineer should enter the appropriate K value supported by documentation and approval by the reviewing authority Design of a sand filter requires input of facility dimensions and outlet structure characteristics running the sand filter scenario and then checking the volume calculations to see if the Percent Filtered equals or exceeds the treatment standard percentage If the value is less than the treatment standard percentage then the user should increase the size of the sand filter dimensions and or change the outlet structure The sand filter input information Bottom Length ft Sand filter bottom length Bottom Width ft Sand filter bottom width Effective Depth ft Height from bottom of sand filter to top of riser plus at least 0 5 feet extra Left Sideslope ft ft H V ratio of horizontal distance to vertical O zero for vertical sand filter sides Bottom Sideslope ft ft H V ratio of horizontal distance to vertical O zero for vertical sand filter sides Right Sideslope ft ft H V ratio of horizontal distance to vertical 0 zero for vertical sand filter sides Top Sideslope ft ft H V ratio of horizontal distance to vertical O zero for vertical sand filter sides Riser Height ft Height of sand filter overflow pipe above sand filter surface Riser Diameter in
96. e same as that developed for BAHM Bay Area Hydrology Model SDHM San Diego Hydrology Model SOHM South Orange County Hydrology Model and WWHM and uses HSPF as its computational engine Like BAHM SDHM and WWHM SMRHM is a tool that generates flow duration curves for the pre and post project condition and then sizes a flow duration control pond basin or vault and outlet structure to match the predevelopment curve The software package consists of a user friendly graphical interface with screens for input of predevelopment and post project conditions an engine that automatically loads appropriate parameters and meteorological data and runs continuous simulations of site runoff to generate flow duration curves a module for sizing or checking the control measure to achieve the hydromodification control standard and a reporting module The HSPF hydrology parameter values used in SMRHM are based on best professional judgment using our experience with calibrated watersheds in other parts of California SMRHM uses the Riverside County long term 15 minute precipitation data records selected to represent Santa Margarita Region County rainfall patterns HSPF is the U S Geological Survey and U S Environmental Protection Agency continuous simulation hydrology software package maintained by AQUA TERRA Consultants The HSPF continuous simulation hydrology model is preferred over single event hydrology models because of its ability to compute and keep
97. e target for the Mitigated scenario compliance The model will accept any land use for this scenario Mitigated is defined as the developed land use with mitigation measures as selected by the user Mitigated is used for sizing stormwater control and water quality facilities The runoff from the Mitigated scenario 1s compared with the Predevelopment scenario runoff to determine compliance with flow duration criteria The Run Scenario button executes the runoff calculations for the scenario shown on the screen Note Any changes made by the user to the element dimensions and other input are not analyzed by SMRHM until the Run Scenario button is clicked 37 Santa Margarita Region Hydrology Model Guidance June 2013 Below the Run Scenario button are the Elements Each element represents a specific stormwater related feature drainage elements flow connections BMPs etc and 1s described in more detail in the following section 38 SCHEMATIC EDITOR SMRHM File Edit View Help Summary Report D c E x Gm ES V DMA 1 Predeveloped Santa Margarita Region Hydrology Model Guidance June 2013 a ER LEM EAA LE DMA Name DMA 1 Surface Interflow Flows To Area in Drainage Management rea Available Pervious Acres lr Erase gt PerviousT otal p Aue m Acre E ue Impervious Total DMA Total Groundwater Show Only Selected Available Impervious Acres a F Roads Flat 0 5
98. een 99 Santa Margarita Region Hydrology Model Guidance June 2013 ph Appendix D Isohyetal Map pdf Adobe Acrobat SE A cete A BD amp E3 amp E 3 8 M 1 W E Tools Comment Share RIVERSIDE COUNTY CONTROL AND WATER CONSERWATION DISTRICT Isohyetal Map for the 85th Percentile 24 hour Storm Event July 2011 The project site s 85 percentile 24 hour rainfall depth can be found on the isohyetal map based on the project s location This is the value that is entered into Rational Method calculations as Dgs 100 Santa Margarita Region Hydrology Model Guidance June 2013 m BMP Design Enter the 85th Percentile 24 hour Rainfall Depth Determine the Effective Impervious Fraction Enter the Area Tributary Type of post development surface cover Effective Impervious Fraction to this Feature acres AT Roots Concrete or Asphalt Grouted or Gapless Paying Blocks Compacted Soil e g unpaved parking Decomposed Granite Permeable Paving Blacks w Sand Filled Gap Class 2 Base Gravel or Class Z Permeable Base Perviaus Concrete Porous Asphalt Open and Porous Pavers Turf black Ornamental Landscaping Natural 5 Soil Natural B Soil Natural Soil Natural D Soil Mixed Surface Types Calculate the composite Runoff Coefficient C for the BMP Tributary rea The effective 1mpervious fraction is calculated in the model based on the tributary area Ar for the post development land cover
99. ent allows the user to route runoff from a land use basin or facility through an open channel to a downstream destination 5 4 2013 307 PM The channel cross section is represented by a trapezoid and is used with Manning s equation to calculate discharge from the channel If a trapezoid does not accurately represent the cross section then the user should represent the channel with an independently calculated SSD Table element or use the Use X Sections option The user inputs channel bottom width channel length channel bottom slope channel left and right sideslopes maximum channel depth and the channels roughness coefficient Mannings n NATURAL CHANNEL value The user can select channel type and x associated Manning s n from a table list directly above the Channel Dimension information or directly input the channel s Manning s n value The channel is used to represent a natural or artificial open channel through which water is routed It can be used to connect a basin to a pond or a pond to a pond or multiple channels can linked together 69 Santa Margarita Region Hydrology Model Guidance June 2013 Channel input information Channel Bottom Width ft Open channel bottom width Channel Length ft Open channel length Manning s n coefficient Open channel roughness coefficient user menu selected or input Slope of Channel ft ft Open channel bottom slope Left Sideslope of Channel ft ft H V rat
100. ention are discussed on page 81 132 Santa Margarita Region Hydrology Model Guidance June 2013 The Riverside County Design Handbook for Low Impact Development Best Management Practices specifies the following criteria for planter box bioretention Min width 2 ft Sideslope O to 1 Max ponding depth 0 5 ft Mulch top layer 2 to 3 inches deep above amended soil layer Min amended soil layer depth 1 5 ft Max amended soil layer depth 3 ft Max amended soil porosity 0 30 Max gravel layer 1 ft below amended soil layer Gravel layer porosity 0 40 Min underdrain diameter 0 5 ft No infiltration to native soil 133 Santa Margarita Region Hydrology Model Guidance June 2013 SAND FILTER BASIN 6 minimum diameter centers solid pipe Overflow 18 min ASTM C 33 sand 10 min gravel layer Section A A Figure courtesy of Riverside County Flood Control and Water Conservation District A sand filter basin allows stormwater to enter the sand filter above ground and then filtrate through the filter media before exiting through a discharge pipe In SMRHM the sand filter basin is represented by the sand filter element 134 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM aca File Edit View Zoom Help Deh e IABSHE OR Cer SO BBE 9 h 4 b h 4 rv A Y MN PRI Ill Schematic Ef S Sand Filter 1 Mitigated Facility Name Outlet 1 Outlet 2 Outlet 3 Downstre
101. entrations of pollutants in receiving waters so treatment design focuses on typical storms which contain the bulk of annual runoff volume Stormwater permits and guidance documents describe the local design criteria for volume based treatment measures which apply to a wider range of projects than the hydromodification management requirements Recommended drawdown times for detention structures are typically at least 48 hours but not to exceed 96 hours 163 Appendix C Santa Margarita Region Hydrology Model Guidance June 2013 3 Flood control design is intended to control peak flows for large sized storms with expected recurrence intervals such as 25 50 or 100 years Flood control facilities typically require capture and detention of a specified volume of stormwater which then is discharged out at flows that can be safely conveyed by downstream channels without undue risk of flooding Flood control facilities usually are required to drain within 24 hours after the end of the design storm in order to be empty for the next storm event This concern that flood control storage remains available for large events has led flood control agencies to require that any storage volume for water quality not be credited for flood control a feature that is sometimes referred to as dead storage Although many factors affect the drawdown time the suggestions below may help SMRHM users in evaluating these other requirements If flow duration control 1s req
102. f the weir to the bottom of the notch Notch Width feet width of notch cannot be larger than the riser circumference For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section Native Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 69 Use Wetted Surface Area sidewalls Yes if infiltration through the trench sideslopes is allowed If infiltration 1s used then the user should consult the Infiltration discussion on page 69 NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor Gravel trench bed receives precipitation on and evaporation from the trench surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should be checked 57 SAND FILTER ELEMENT SMRHM santa Margarita Region Hydrology Model Guidance June 2013 Eje dt bew Hep ummary Report e ei s S s develoned B5 EL zl A Sand Filter 1 Mitigated tal Facility Name x IE ai TO E Filter mabenal depth H Total Volume Fitrated ac t Total Volume Through Riser acf Total Volume ect Percent Fiketed Size Infiltration Basin
103. ffsetfin Swale Bottom Elevation ft Orifice Diameter in le Jo Swale Dimensions Flow Through Underdrain ac ft 14 663 Swale Length ft mn Total Outflow ac ft 113 338 Swale Bottom Width ft Percent Through Underdrain 12 34 Facility Dimension Diagram Effective Total Depth ft Riser Dutlet Structure Bottom slope of Swale ft ft Outlet Structure Data Top and Bottom side slope ft ft Riser Height Above Swale surface ft o5 a Left Side Slope H RiserDiameter in o4 Right Side Slope HAY Riser Type Flat Material Layers for Swale Notch Type Layer Layer2 Layer3 Peat Y Amended 5 in h y Orifice Diameter Height EI Number in ft Edit Soil Types um E d E 2 o Jl KSat Safety Factor 3 h None C 2 C4 Show Swale Table Open Table Swale Volume at Riser Head ac ft 109 m Move Elements e ease Y fig H Native Infiltration NO Er dle lt 6 5 2013 223PM___ The bioretention dimensions and parameters to adjust to represent the bioretention standard design are discussed on page 81 The Riverside County Design Handbook for Low Impact Development Best Management Practices specifies the following criteria for bioretention standard design Min width 6 ft Sideslope 4 to 1 Max ponding depth 0 5 ft Mulch top layer 2 to 3 inches deep above amended soil layer Min amended soil layer depth 1 5 ft Max amended
104. ft 3 124 Total Volume Through Facility ac ft 400 83 Show Pond Table Open Table a Percent Infiltrated 100 AS Stage f T Size Infiltration Pond Target 100 Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft o Downstream Connection Overflow Elevation ft fo Iterations 0 r Move Elements a oy Ne km n lt 6 5 2013 8 44 AM The pond dimensions and parameters to adjust to represent an infiltration basin are Bottom Length ft Infiltration basin length Bottom Width ft Infiltration basin width Effective Depth ft Infiltration basin height from basin bottom to top of riser plus at least 1 0 foot of freeboard Left Sideslope H V ratio of horizontal distance to vertical for infiltration basin sides Bottom Sideslope H V ratio of horizontal distance to vertical for infiltration basin sides Right Sideslope H V ratio of horizontal distance to vertical for infiltration basin sides Top Sideslope H V ratio of horizontal distance to vertical for infiltration basin sides Riser Height ft Height of infiltration basin pond overflow pipe above basin soil surface Riser Diameter 1n Infiltration basin overflow pipe diameter Riser Type Flat Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate 1n hr Native soil infiltration rate Infiltration Reduction Fac
105. garita Region Hydrology Model Guidance June 2013 TRAPEZOIDAL POND ELEMENT igpueumH Qv Sana DOG oidal Pond 1 Mitigated A Facility Type TrapezcidalPond Outlet 2 Outlet 3 Auto Pond Guick Fond Facility Dimension Diagram Facility Dii dAsione Faciity Bottom Elevation It Bottom Length It Bottom Width it EHective Depth it Left Side Slope HV Bottom Side Shope H V Right Side Slope HAV Top Side Slope H V Orifice Diameter Height Infiltration It Number in Pond Volume al Fires Head act Show Pond Table OpenTable Initial Stage ft Tide Gate Time Series Demi Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation H o Downstream Connection z Overflow Elevation It Es kerations amp 4j2013 135 PM In SMRHM there is an individual yo III pond detention basin element for each type of pond and stormwater control facility The pond element shown above is for a trapezoidal pond This is the most common type of stormwater pond A trapezoidal pond has dimensions bottom length and width depth and sideslopes and an outlet structure consisting of a riser and one or more orifices to control the release of stormwater from the pond A trapezoidal pond includes the option to infiltrate runoff if the soils are appropriate and there is sufficient depth to the underlying groundwater table TRAPEZOIDAL POND
106. gh an iteration process by which it changes the pond dimensions and outlet configuration then instructs SMRHM to again compute the resulting Mitigated runoff compare flow durations and decide if it has made the results better or worse This iteration process continues until Auto Pond finally concludes that an optimum solution has been found and the Mitigated flow duration values in red are as close as possible to the Predevelopment flow duration values in blue When this occurs the Auto Pond Finished message appears on the screen 21 Santa Margarita Region Hydrology Model Guidance June 2013 The user has the option to continue to manually optimize the pond by manually changing pond dimensions and or the outlet structure configuration Manual optimization 1s explained in more detail on page 48 After making these changes the user should click on the Optimize Pond button to check the results and see if Auto Pond can make further improvements File Edit View Help Summary Report Duk 5 a6 p sj amp lkiti Oe SER ra ru ra ATA ra ul El EB Schematic mE V Trapezoidal Pond 1 Mitigated Facility Name Facility Type Run gt Outlet 1 Outlet 2 Outlet 3 Scenario Downstream Connections IV Precipitation Applied to Facility EMO EANA Quick Pond NM Evaporation Applied to Facility Facility Dimension Diagram e A Outlet Structure Data Facility Bottom Elevation ft Riser Height ft B a Beton tanga gy 67
107. gth to Width Ratio This bottom length to width ratio will be maintained regardless of the pond size or orientation The default ratio value is 1 0 Pond Sideslopes Auto Pond assumes that all of the pond s sides have the same sideslope The sideslope is defined as the horizontal distance divided by the vertical A typical sideslope is 3 3 feet horizontal to every 1 foot vertical The default sideslope value is 3 Choose Outlet Structure The user has the choice of either one orifice and rectangular notch or three orifices If the user wants to select another outlet structure option then the pond must be manually sized Create Pond This button creates a pond when the user does not input any pond dimensions or outlet structure information Any previously input pond information will be deleted Optimize Pond This button optimizes an existing pond It cannot be used if the user has not already created a pond Accept Pond This button will stop the Auto Pond routine at the last pond size and discharge characteristics that produce a pond that passes the flow duration criteria Auto Pond will not stop immediately if the flow duration criteria have not yet been met The bottom length and width and volume at riser head will be computed by Auto Pond they cannot be input by the user Auto Vault and Auto Tank operates the same way as Auto Pond There are some situations where Auto Pond will not work These situations occur when complex routing con
108. heta 2 c 0 3392 0 0024318 Theta 0 00004715 Theta 2 YoverH Headr NotchBottom Headr Coef a b Headr c Headr 2 q Coef Tan Theta 2 Headr 5 2 These equations are provided from the Washington State Department of Ecology s 2005 Stormwater Management Manual for Western Washington The outlet designs are shown 61 Santa Margarita Region Hydrology Model Guidance June 2013 below They have been reproduced from Volume III of the Stormwater Management Manual for Western Washington which has more information on the subject Q CA V2 CAVE CVZ AWh Ata hb distance from hydraulic grade fine at the 2 year flow of the outflow pipe to the overflow elevation Figure 3 20 Simple Orifice The diameter of the orifice is calculated from the flow The orifice equation is often useful when expressed as the orifice diameter in inches d Ea equation 5 where d orifice diameter inches Q flow cfs h hydraulic head ft 62 Santa Margarita Region Hydrology Model Guidance June 2013 SECTION NTS Figure 3 21 Rectangular Sharp Crested Weir Q C L 0 2H H equation 6 where Q flow cfs C 3 27 0 40 H P ft H P are as shown above L length ft of the portion of the riser circumference as necessary not to exceed 50 percent of the circumference D inside riser diameter ft Note that this equation accounts for side contractions by subtracting 0
109. ht tt 07259 Right Side Slope H V Kop site ipe EUY Orifice Diameter Height Infiltration a Number in IERS 4 4 Mingated Pond Volume at Riser Head ac ft 2171 Show Pond Table Open Tabie Initial Stage f Tide Gate Time Series Demand Determine Outlet With Tide Gate 7 Use Tide Gate Tide Gate Elevation ff 6 Downstream Connection Overflow Elevation H 6 iterations 6 Mi m ar v r TS MVP To exit SMRHM click on File in the upper left corner and select Exit Or click on the X in the red box in the upper right hand corner of the screen 34 Santa Margarita Region Hydrology Model Guidance June 2013 MAIN SCREENS SMRHM has six main screens These main screens can be accessed through the buttons shown on the tool bar above or via the View menu The six main screens are e Map Information e General Project Information e Analysis e Reports e Tools e LID Low Impact Development Analysis Each is discussed in more detail in the following sections 35 Santa Margarita Region Hydrology Model Guidance June 2013 MAP INFORMA TION SCREEN SMRHM Example File Edit View Help Summary Report Oem 856 m HSumHOursaag ooo eu En Santa Mar garita Santa Margarita y Site Information Site Name Address City Sape Precip Factor Map Controls ejes 4 3 7 2013 1 50 PM The Map screen contains county information The p
110. ice 1s usually located at the bottom of the pond and or above any dead storage in the facility The user can set the diameter and height of each orifice The user specifies the riser type as either flat or notched The weir notch can be either rectangular V notch or a Sutro weir The shape of each type of weir is shown below Top Vidth Bottom Width Width Rectangular Notch V Notch Sutro 60 Santa Margarita Region Hydrology Model Guidance June 2013 By selecting the appropriate notch type the user 1s then given the option to enter the appropriate notch type dimensions Riser and orifice equations used in SMRHM are provided below Headr the water height over the notch orifice bottom q discharge Riser Head Discharge Head water level above riser q 9 739 Riser Diameter Head 1 5 Orifice Equation q 3 782 Orifice Diameter 2 SORT Headr Rectangular Notch b Notch Width 1 0 2 Headr where b gt 0 8 q 3 33 b Headr 1 5 Sutro Wh Top Width Bottom Width Top Width Notch Height Headr Wd Bottom Width Wh the difference between the bottom and top widths Ql rectangular notch q where Notch Width Wh Q2 rectangular notch q where Notch Width Wd q Q1 0Q2 2 V Notch Notch Bottom height from bottom of riser to bottom of notch Theta Notch Angle a 2 664261 0 0018641 Theta 0 00005761 Theta 2 b 0 48875 0 003843 Theta 0 000092124 T
111. ices see discussion in OUTLET STRUCTURE CONFIGURATIONS section Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate 1n hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 69 Use Wetted Surface Area sidewalls Yes if infiltration through the pond sideslopes is allowed If infiltration is used then the user should consult the Infiltration discussion on page 69 NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor A pond receives precipitation on and evaporation from the pond surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should be checked 47 Santa Margarita Region Hydrology Model Guidance June 2013 circumference length of opening sized for 100 yr fiow SECTION B B has 2 options L as required tor 6 depth gg 1 XT M 2 aT min 2 asphalt emergency overflow water surface VO AMEN UG ICONE TONO Jan arca s da 4 Y Z qe f CA AN 1 ft rock himno overfiow design how W w embankment Outlet Protection in Vol Il SECTION C C NTS Figure 3 10 Typical Detention Pond Sections NOTE The detention pond section diagram shows the general configuration used in designing a po
112. igated Start Date All Datasets Flow Stage Precip Evap POC 1 End Date A 6 4 2013 3 57 PM The drawdown screen is used to compute pond stages water depths These stages are summarized and reported in terms of drain retention time 1n days For this example the maximum stage computed during the entire 30 50 year simulation period is 3 40 feet This maximum stage has a drawdown time of 1 day 20 hours 33 minutes 8 seconds approximately 45 hours Ponds may have drain times in excess of the allowed maximum This can occur when a pond has a small bottom orifice If this 1s not acceptable then the user needs to change the pond outlet configuration manually run the Mitigated scenario and repeat the analyze stage computations A situation may occur where it is not possible to have both an acceptable pond drawdown retention time and meet the flow duration criteria NOTE The flow duration criteria take precedence unless the user is instructed otherwise by Appendix C or the local municipal permitting agency 95 Santa Margarita Region Hydrology Model Guidance June 2013 HYDROGRAPHS SMRHM Example1 File Edit View Help Summary Report Dc E X Ba BS LuEIixs i4imBx OOG Create Graph Add Data File Previous Plots IV Record Plots 1 ELSINORE EVAP 2 Temecula Valley Start Date 1974 10 01 00 00 TT ese 22 IRRIGATION IN INCHES End Date zad 501 POC 1 Predeveloped flow 2011 03 30 24
113. imported as a time series page 76 and applied to the post project scenario instead of the simulated precipitation record If additional live storage 1s needed it may be added to upper levels of the same facility or provided elsewhere on the site Guidance by Other Agencies Some agencies in other parts of the United States have developed extensive guidance for design of stormwater management measures Two manuals are discussed below that provide detailed discussions or examples that may be helpful to users of SMRHM although the suitability of these recommendations for Riverside County conditions has not been verified These documents can help provide context and ideas for users for SMRHM but adapting these ideas requires the exercise of professional engineering judgment Mention of the procedures and details in these documents does not imply any endorsement or guarantee that they will be appropriate for addressing the Hydromodification Management Standards in Santa Margarita Region County jurisdictions Stormwater Management Manual for Western Washington SWMMWWo was prepared by the Washington Department of Ecology for implementation in 19 counties of Western Washington The latest 2012 edition in 5 volumes is on the Web at http www ecy wa gov programs wq stormwater manual html Design recommendations from this manual were the basis for many features of the WWHM that have been carried over into SMRHM Portions of Volume 3 Hydrology that
114. ine down to the 22 43 32 uS trapezoidal pond with the mouse pointer and click on the pond This action will bring up the From Basin to Conveyance screen Flow From w Surface Flow wv nterflowi As with the Predevelopment scenario we want to only connect the surface flow and the interflow shallow subsurface runoff from the basin to the pond Click OK Groundwater 13 SMRHM santa Margarita Region Hydrology Model Guidance June 2013 File Edit View Help Summary Report Dc E MM Schematic Commercial Toolbox e pmueummowosssiaa coosc aW Trapezoidal Pond 1 Mitigated Facility Name Trapezoidal Pond 1 Facility Type Trapezcidal Pond Outlet 1 Outlet 2 Outlet 3 Downstream Connections v Precipitation Applied to Facility Auto Pond Quick Pond Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft Riser Height ft omm a Bottom Length ft Riser Diameter in 0 Bottom Width ft Riser Type Flat 4 Effective Depth ft Notch Type Left Side Slope HZA Bottom Side Slope H Right Side Slope H V Top Side Slope HV EM D p ll pl E NEM f0 eo Orifice Diameter Height Number in ft Eo o me CN o ui o na uo Pond Volume at Riser Head ac ft 0 Show Pond Table OpenTable Initial Stage ft i 1 Infiltration Tide Gate Time Series Demand Determine Outlet
115. ined by computing the saturation level of the lowest soil layer first Once the lowest soil layer is saturated and flow begins then the gravity head is considered to be at the saturation level of the lowest soil layer Once the lowest soil layer is saturated completely then the head will include the gravity head from the next soil layer above until gravity head from all soil layers 1s included Gravity head from ponding on the surface is included in the orifice calculations only if all of the intervening soil layers are saturated 3 There is native infiltration but no underdrain Discharge infiltration into the native soil is computed based on a user entered infiltration rate in units of inches per hour Specific head conditions are not used in determining infiltration into the native soil Any impact due to head on the infiltration rate 1s considered to be part of the determination of the native soil infiltration rate Because it is possible to have a maximum of three soil layers each modeled layer must overcome matric head before infiltration to the native soil can begin Once matric head is overcome by gravity head for all modeled layers then infiltration begins at a maximum rate determined either by the ability of the water to move through the soil layers or by the ability of the water to infiltrate into the native soil whichever 1s limiting 173 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 4 There 1s both a
116. io of horizontal distance to vertical O zero for vertical channel sides Right Sideslope of Channel ft ft H V ratio of horizontal distance to vertical O zero for vertical channel sides Maximum Channel Depth ft Height from bottom of channel to top of channel bank Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate 1n hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 69 Use Wetted Surface Area sidewalls Yes if infiltration through the channel sideslopes is allowed If infiltration 1s used then the user should consult the Infiltration discussion on page 69 NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor 70 FLOW SPLITTER ELEMENT SMRHM santa Margarita Region Hydrology Model Guidance June 2013 Eje dt bew Hep ummary Report ele eel iL us 3 zie ze i al Flow Splitter 1 Mitigated Facility Name Downstream Connection ALTA SE MAA o Both Exits Primary Exit Secondary Exi 2 Trapezaidal Pond 1 Channel 1 Upstream Storage Areas Length H 0 Primary Exit 1 Structure Cortrol Structure ed Orfice Diameter Height Number in ft ip se 4 p se 3 a0 lt p y Vol
117. ipe if Underdrain Used box 1s checked Water enters the underdrain when the amended soil becomes saturated down to the top of the underdrain The underdrain pipe fills and conveys water proportionally to the depth of amended soil saturation When the amended soil is fully saturated the underdrain pipe 1s at full capacity Discharge from the underdrain pipe is controlled by the underdrain orifice diameter If native infiltration 1s turned on then native infiltration will start when if Water starts to fill the underdrain 1f an underdrain 1s used 2 Water enters the amended soil af Use Wetted Surface Area sidewalls is set to YES 3 Water saturates the amended soil layer s to 2 3rds of the total amended soil depth if there is no underdrain and Wetted Surface Area is set to NO 83 Santa Margarita Region Hydrology Model Guidance June 2013 Santa Margarita Region Hrdrolen Model DSU im REA AA set Il Schematic O X Bio Swale 1 Mitigated Lj d BID Facility Hame Bia Swale 1 Run Outlet 1 Outlet 2 Outlet 3 Scenario Bioretenbon Svale Default Swale Underdrain Used levation ft 0 1 Swale Dimensions Flow Through Underdram ac R i Swale Length fit noo Total Ciuiflow act Swale Bottom width A loo Percent Thecugh Underdrain Freebosrd Ht nooo s Facility Dimension Diagram load Flooding 1 0 000 Outlet Structur
118. k on the DMA and highlight Connect to Point of Compliance the point of compliance is defined as the location at which the runoff from both the Predevelopment scenario and the Mitigated scenario are compared The Point of Compliance screen will be i shown for Predevelopment DMA 1 The fu us POC Point of Compliance Outlet has been Element DMA 1 checked for both surface runoff and interflow shallow subsurface flow These are the two flow components of stormwater v Surface Flow runoff Do not check the groundwater box unless there is observed and documented base flow on the project site POC Outlet e Interflow Groundwater Connect Click the Connect button in the low right E corner to connect this point of compliance to the Predevelopment basin Santa Margarita Region Hydrology Model Guidance June 2013 CMA ASW Or SBE DOO EI Schematic M im ix ad DMA 1 Predeveloped Ei DMA Name Surlace Inteiflovs Groundwater Flows To Area in Drainage Management rea Show Onky Selected Available Pervious Acres Available Impervious Acres jr Eines JP r Resmraosy p Eva Je r tama Tf SR lr BUbmMedEi Tp a mi r brenr IT C bfeesMedS10 RESTE M OD Foesve di EN IT ED ShwbModE iit r Ob tabVeo 2 0 JP ED bra Mods 10 i M iensen o Ta E Isi TT 7 de ears S21AM After the point of compliance has been a
119. l street names are shown on the map Santa Margarita Region Hydrology Model Guidance June 2013 2 Select the project site location Locate the project site on the map Use the map controls to magnify a portion of the map 1f needed Select the project site by left clicking on the map location A red circle will be placed on the map identifying the project site 7 SMRHM File Edit View Help Summary Report santa Margarita Santa Margarita Site Name Address Ci The model will then automatically select the appropriate rain gauge record for the project site The Santa Margarita Region has four long term 15 minute precipitation records Eastern Slopes Temecula Valley Western Plateau and Wildomar North Murrieta For this example we will use the Temecula Valley rain gauge The site name address and city information 1s optional It is not used by SMRHM but will be included in the project report summary Santa Margarita Region Hydrology Model Guidance June 2013 3 Use the tool bar immediately above the map to move to the rw Scenario Editor Click on the General Project Information button The General Project Information button will bring up the Schematic Editor SMRHM Eje Edi view Zoom Help The schematic editor screen contains two scenarios DNEH Da Predevelopment and Mitigated ie s I Schematic E a Ed R Predeveloped Mitigated f First set up the Predevelopment
120. low and the 5 year flow and 110 for flow levels values between the 5 year flow and the upper threshold value If the percentage value does not exceed this maximum ratio 100 for the lower threshold to the 5 year flow value and 110 for the 5 year flow value to the 10 year value then the Pass Fail column shows a Pass for that flow level If they are exceeded then a Fail is shown A single Fail and the facility fails the flow duration criteria The facility overall Pass Fail 1s listed at the top of the flow duration table 93 Santa Margarita Region Hydrology Model Guidance June 2013 FLOW FREQUENCY SMRHM Example1 File Edit View Help Summary Report Dci Ba PERE Or SO FILEE Analysis Flow Frequency Cumulative Probability Elon atay aa RM 6 2050 3 1306 8 6568 4 1453 11 3924 5 9575 Annual Peaks 12 4123 5 7931 2 5295 4 4180 3 2368 4 7101 1 12125 2 0295 2 1702 Os O Oi 5 WH PA A oe xt x X X XXXX 10 20 30 50 70 80 95 1976 2264 3883 3193 3236 8480 4328 0918 2469 2324 5237 1713 8814 5282 1372 2526 5511 4133 3971 5327 0519 Durations Flow Freguency Hydrograph LID BMP Sizing Analyze datasets 501 POC 1 Predeveloped flow 801 POC 1 Mitigated flow All Datasets Flow Stage Precip Evap PDC 1 2 0 2 0 1 9 2 6 1 3 4 1 0 0 3 0 0 3 0 4 2 3 16 4 2013 3 54 PM Flow frequency plots are shown on the left and the 2 5
121. lue of O The pond bottom is assumed to be flat The pond outlet structure consists of a riser and zero to three orifices The riser has a height typically one foot less than the effective depth and a diameter The riser can have either a flat top or a weir notch cut into the side of the top of the riser The notch can be either rectangular V shaped or a Sutro weir More information on the riser weir shapes and orifices is provided later in this guidance document After the pond is given dimensions and outlet information the user can view the resulting stage storage discharge table by clicking on the Open Table arrow in the lower right corner of the pond information screen This table hydraulically defines the pond s characteristics The user can use either Auto Pond to size a pond or can manually size a pond Follow the steps below for manual sizing a pond using an outlet configuration with one orifice and a riser with rectangular notch this 1s usually the most efficient design l Input a bottom orifice diameter that allows a discharge equal to the lower threshold e g 10 of 2 year Predevelopment flow for a stage equal to 2 3 the height of the riser This discharge can be checked by reviewing the pond s stage storage discharge table 46 Santa Margarita Region Hydrology Model Guidance June 2013 2 Input a riser rectangular notch height equal to 1 3 of the height of the riser Initially set the riser notch width to 0 1 foot
122. m Help AE zaueumdoeowouHiuccos MM Schematic Predeveloped ESL Facility Name Bioretention Planter Box Outlet 1 Outlet 2 Scenario Downstream Connection p O 1 p 35 p Facility Type Drainage Elements Use simple swale Default Swale El iv Underdrain Used Underdrain Diameter ft 05 Offsetfin Swale Bottom Elevation fi 0 Orifice Diameter in le fo Swale Dimensions Flow Through Underdrain ac ft 0 937 Swale Length ft Total Outflow ac ft 111 637 Swale Bottom Width ft 00 Percent Through Underdrain 0 84 Freeboard ft ooo Facility Dimension Diagram Effective Total Depth ft Riser Dutlet Structure a Bottom slope of Swale ft ft 001 Outlet Structure Data Top and Bottom side slope ft ft 000 Riser Height Above Swale surface ft o5 a Left Side Slope HA Riser Diameter in 24 4 Right Side Slope H V 000 Riser Type Flat H Material Layers for Swale Notch Type Layer Layer2 Layer 3 Peat Y Amended 5 in h y Orifice Diameter Height GRAVEL y Number in ft Edit Soil Types E dilo H 2b 4c KSat Safety Factor ZZ sh eco Move Elements None C2 C 4 Show Swale Table OpenTable 4 Swale Volume at Riser Head ac ft 037 lt a y gt Native Infiltration No Save xy Load x y Flow Connections 6 5 2013 2 40 PM The bioretention dimensions and parameters to adjust to represent the planter box bioret
123. ment Load Element Run Predeveloped Run Mitigated Clear All B Forest Mod 5 10 fs B Forest Stee 10 20 fo Import Basin Location Pervious otal Face p Actes B Aces Impervious Total DMA Total Interflow Groundwater Show Only Selected Available Impervious Acres a Roads Flat 0 5 pd Ruhe ____ 0 iros OS Ail DeselectZero Select By GO KE y lt Eta NM 10 50 Ahd Place the trapezoidal pond element below the DMA in any cell on the grid It doesn t have to be directly below the DMA but it must be somewhere on a lower row in the grid Right click on the DMA and select Connect To Element A green line will appear with one end connected to the DMA 12 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM File Edit View Help Summary Report Du i 66 FELLE MKIII LACEE seje Ek Y DMA 1 Mitigated DMA Name Designate as Bypass for POC Surface Interflow Groundwater Flows To Available Pervious Acres xlr Fosen Move put PerviousT otal pp Acres lt a 4 Impervious Total PO O Acres DMA Total Poo Acres Area in Drainage Management Area Show Only Selected Available Impervious Acres a M Roads Flat 0 5 RefAes Pme i DeselectZero Select By GO 5 4 2013 9 29 AM Pull the other end of the l
124. mpliance 1 Jo o ci a Element Trapezoidal Pond 1 3 D POC Outlet SelectPOC ADD Pond Volume at Riser Head ac ft 0 Z Outlet 1 Show Pond Table OpenTable Initial Stage ft Commercial Toolbox Connect Tide Gate Time Series Demand Move Elements Determine Outlet With Tide Gate pn LI Use Tide Gate Tide Gate Elevation ft fo Downstream Connection y Save xy Y Load xy Overflow Elevation ft a Iterations a REI ti To amp 16 4 2013 3 34 PM The point of compliance is selected by right clicking on the element at which the compliance analysis will be made In the example above the point of compliance analysis will be conducted at the outlet of the trapezoidal pond Additional points of compliance can be added by clicking on the ADD button and then highlighting the POC number to be used for the element Once a POC number is added it cannot be removed but if it is not used then it has no effect 85 Santa Margarita Region Hydrology Model Guidance June 2013 Once the point of compliance has been Santa Margarita Region Hydrology Model na Ele Edit Wew Hep ummary Report selected the element is modified on the Ose ine Schematic screen to include a small box le e d E ASIS with the letter A for Analysis in the II Schematic lower right corner This identifies the outlet from this element as a point of
125. n WWHM Version 4 170 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 Santa Margarita Region Hydrology Model Guidance May 2013 SMRHM computes stormwater runoff for a site selected by the user SMRHM runs HSPF in the background to generate a 15 minute runoff time series from the available rain gauge data over a number of years Stormwater runoff 1s computed for both predevelopment and post project land use conditions Then another part of the SMRHM routes the post project stormwater runoff through a stormwater control facility of the user s choice SMRHM uses the predevelopment peak flood values from a partial duration series of individual peak events to compute the predevelopment 2 year through 25 year flood frequency values The post project runoff 2 year through 25 year flood frequency values are computed at the outlet of the proposed stormwater facility The model routes the post project runoff through the stormwater facility As with the predevelopment peak flow values partial duration post project flow values are selected by the model to compute the developed 2 year through 25 year flood frequency The predevelopment 2 year peak flow is multiplied by a percentage 10 percent to set the lower limit of the erosive flows 1n accordance with the current HMP performance criteria The predevelopment 10 year peak flow is the upper limit A comparison of the predevelopment and post project flow duration curves 1s con
126. n the Analysis screen NOTE This information is not required for basic sizing of the flow duration facility but can assist the user in determining the overall suitability of the mitigated design in meeting additional related requirements for treating stormwater runoff and minimizing risk of vector mosquito breeding problems See page 98 for more descriptions of this SMRHM feature and Appendix C for discussion and references for these requirements Click on the Stage tab at the bottom to get the Mitigated pond stage time series 26 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM glueums53 w5i3Bu vo Drawdown Analysis Select anabens lor 1001 Trapezesdal Pond 1 STAGE Mibigated Analyze Stage Pond Pond Drain Time day Stage leet Percent of Total Run Time Max Stage UZ DiwdownTimelddhhmmss BU OAM Click on the tab labeled Drawdown This is where the pond drawdown retention time results will be shown 27 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM File Edit View Help Summary Report D xg M Analysis Drawdown Analysis Select analysis for 1001 Trapezoidal Pond 1 STAGE Mitigated Analyze Stage Pond Pond Drain Time days Stage feet Percent of Total Run Time 1 Max Stage Drawdown Time dd hh mm ss o Durations Flow Frequency Drawdown LID BMP Sizing Analyze datasets 1001 Trapezoidal Pond 1 STA
127. n trench soil layer depth Layer 1 Porosity Infiltration trench soil porosity Layer 2 Thickness ft Infiltration trench gravel layer depth Layer 2 Porosity Infiltration trench gravel porosity Layer 3 Thickness ft Infiltration trench gravel layer depth Layer 3 Porosity Infiltration trench gravel porosity NOTE Layers 2 and 3 are optional Riser Height ft Height of infiltration trench overflow pipe above trench bottom If a weir is preferred instead of a riser then set the riser height to the weir height and set the riser diameter to the weir length 123 Santa Margarita Region Hydrology Model Guidance June 2013 Riser Diameter in Infiltration trench overflow pipe diameter Riser Type Flat Native Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate 1n hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 69 If infiltration 1s used then the user should consult the Infiltration discussion on page 69 Any changes made by the user to the element dimensions and other input are not analyzed by SMRHM until the Run Scenario button is reclicked The Riverside County Design Handbook for Low Impact Development Best Management Practices specifies the following criteria for infiltration trenches Max drawdown 72 hrs Max tributary area 10 ac Max depth 8 ft Sideslope 0 to 1 vertical e Trench width must be gre
128. n underdrain and native infiltration Underdrain flow and native infiltration are computed as discussed above However there is one other limitation to consider In the case where the flow through the soil layer 1s less than the sum of the discharge through the underdrain and the native infiltration then the flow through the soil layer becomes the limiting flow and must be divided between the native infiltration and the underdrain This division 1s done based on the relative discharge rates of each Note that wetted surface area can be included in the discharge calculations by adding the infiltration through the wetted surface area to the lower soil layer and the upper surface layer individually This is done by computing the portion of the wetted surface area that 1s part of the upper surface layer and computing the infiltration independently from the portion of the wetted surface area that 1s part of the lower soil layers There are several equations used to determine water movement from the surface of the bioretention facility through the soil layers and into an underdrain or native infiltration The water movement process can be divided into three different zones 1 Surface ponding and infiltration into the top soil layer soil layer 1 2 Percolation through the subsurface layers 3 Underdrain flow and native infiltration 174 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 The modified Green Ampt equation
129. nd and its outlet structure This diagram is from the Washington State Department of Ecologys 2005 Stormwater Management Manual for Western Washington Consult with your local municipal permitting agency on specific design requirements for your project site 48 Santa Margarita Region Hydrology Model Guidance June 2013 VAULT ELEMENT SMRHM Ele Edt yew Hep ummary Report DS DMA L Schematic Run Scenario lt i Vault 1 Mitigated developed LIFE Facility Name Downstream Connection 7 Precpiation Appbed to Facity Evaporation Appbed to Facit Facility Dimensions Use Tide Gate Tide Gate Elevation H Overflow Elevation If THE am al ALLERTA Outlet 1 Outlet 2 Outlet 3 Auto Vault Quick Vault Fired Width For Auto Vault Facility Dimension Diagram Outlet Structure Data Rise Heght Wi 9 H Heer Diameter m lo Riser Type fi Notch Type Orifice Diameter Height Number in it Io 2 p Hho c Vault Volume al Fiser Head ac f JOGO Show Vault Table Openlate Initial Stage tt m es Tide Gate Time Series Demand Determine Outlet With Tide Gate 0 Downstream Connection m o iterations lo 5 4 2013 1 07 PM The storage vault has all of the same characteristics of the trapezoidal pond except that the user does not specify the sideslopes by definition they are zero and the vault is
130. nimum allowable bottom orifice diameter even if this size diameter is too large to meet flow duration criteria for this element Additional mitigating BMPs may be required to meet local hydromodification control requirements Please see Appendix C or consult with local municipal permitting agency for more details For manual sizing information see page 48 22 Santa Margarita Region Hydrology Model Guidance June 2013 6 Review analysis SMRHM Example Eje Edit view Heb Summary Report Dc E amp plaueHmsvewsuplzEkEOSOSO BE Analysis 1 ELSINORE EVAP 2 Temecula Valey 22 IRRIGATION IH INCHES 501 POC 1 Predeveloped Row 1000 Trapezoidal Pond 1 ALL OUTLETS Mibgated 1001 Trapezoidal Pond 1 STAGE Mibgated RAD HT dr 65m3 313 PM The Analysis tool bar button third from the left brings up the Analysis screen where the user can look at the results Each time series dataset is listed in the Analyze Datasets box in the lower left corner 23 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM Ele Edt yew Heb Summary Report D x3 pasma Gui Bu occ Analysis E The Facility PASSED 8 65 The Facility PASSED Predev Mit Percentage Pass Fail 1854 1854 1060 Pass 1551 1453 23 Fass 1431 1256 BT Pass 1287 1054 a5 Pass 1156 972 B4 Pass 1049 273 83 Pass 563 793 B2 Pass BER 704 79 Fass 822 634 TT Pass 753 ETT 76 Fass 700 517 73 Pass 645 482 7
131. oads Flas0 55 Roads Modi5 105 Roads Sbeep 10 205 Rosdi Veiy5tes gt 20 Roo Ama Drenas Flst 0 5 Driveways Mod 5 105 Driveways 5 10 20 Dee Mendo 2007 Save xy Load x y la r 5 4 2013 1 03 PM The impervious lateral basin is similar to the standard land use basin except that the surface runoff from the lateral impervious basin goes to another adjacent lateral basin 1mpervious or pervious rather than directly to a conveyance system or stormwater facility By definition the impervious lateral basin contains only impervious land types Pervious area is handled separately with the pervious lateral basin Lateral Basin The user selects the impervious lateral basin land type by checking the appropriate box on the Available Impervious Coverages IMPLNDs screen This information is automatically placed in the Impervious Type IMPLND box above Once entered the land type can be changed by clicking on the Change button on the right The user enters the number of acres represented by the lateral impervious basin land type To model parking lot runoff dispersion onto adjacent lawn connect the Lateral I Basin the parking lot to the downstream Lateral Basin the lawn In the model s calculations surface runoff from the parking lot is added to the surface of the lawn urban vegetation The total runoff will then be directed to a stormwater conveyance system selected by the user 44 Santa Mar
132. of the bioretention facilitys hydrologic processes Evapotranspiration removes water from bioretention surface ponding and the soil column during non storm periods The routine will satisfy potential evapo transpiration PET demands in the same sequence as implemented in HSPF l Water available from vegetation interception storage 2 Water available from surface ponding 3 Water available from the bioretention soil layers top layer first 177 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 Water will be removed from vegetation interception storage and surface ponding and the bioretention soil layers starting at the top layer down to the rooting depth at the potential rate Water is taken from the soil layers below the rooting depth based on a percentage factor to be determined Without this factor there will be no way to remove water from below the rooting depth once 1t becomes completely saturated 178
133. oil prior to discharging into a conveyance system The pervious lateral basin is similar to the standard land use basin except that the runoff from the lateral basin goes to another adjacent lateral basin 1mpervious or pervious rather than directly to a conveyance system or stormwater facility By definition the pervious lateral basin contains only a single pervious land type Impervious area is handled separately with the impervious lateral basin Lateral I Basin The user selects the pervious lateral basin land type by checking the appropriate box on the Available Soil Types PERLNDS screen This information is automatically placed in the Soil Types PERLNDs box above Once entered the land type can be changed by clicking on the Change button on the right The user enters the number of acres represented by the lateral basin land type If the lateral basin contains two or more pervious land use types then the user should create a separate lateral basin for each 43 Santa Margarita Region Hydrology Model Guidance June 2013 LATERAL I BASIN ELEMENT Impervious SMRHM Ele Edit Wew Heb Summary Report Dae 5 te PERSIA EB NAO UA Amas EN Schematic Ox SX Lateral i Basin 1 Predeveloped Element Name Runoff Type Surface Interflow Groundwater Downstream Connection Element Type Lateral Impervious Flow Bann Imperio IMP ND Type change Lateral Flow IMPUND Available mpertous coverages IMPLNDSs R
134. on In SMRHM the bioretention vertical sideslopes is represented by the bioretention element 130 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM File Edit View Zoom Help eS ABSHEA Or 8S BERD OG MM Schematic Z Xx Y Bioretention Vertical Side Slopes Mitigated Facility Name Bioretention Vertical Side Slopes Outlet 1 Outlet 2 Outlet 3 Predeveloped ca Downstream Connection Facility Type l Use simple swale Default Swale iv Underdrain Used Underdrain Diameter ft 55 Offsetfin Swale Bottom Elevation ft Orifice Diameter in le J0 Swale Dimensions Flow Through Underdrain ac ft 4 569 Swale Length ft 00 000 Total Outflow ac ft 111 778 Swale Bottom Width ft Percent Through Underdrain 4 09 000 Facility Dimension Diagram Effective Total Depth ft Riser Outlet Structure E Bottom slope of Swale ft ft 001 Outlet Structure Data Top and Bottom side slope ft ft 000 Riser Height Above Swale surface ft o5 a Left Side Slope H RiserDiameter in o4 Right Side Slope HAY 000 Riser Type Flat Material Layers for Swale Notch Type Layer Layer2 Layer 3 Peat Y Amended 5 in h y Orifice Diameter Height EI Number in ft Edit Soil Types um E d E 2 o Jl KSat Safety Factor 3 h None C 2 C4 Show Swale Table Open Table Swale Volume at Riser Head ac ft 048 Native Infiltration NO elelelel o i o e c
135. onditions of this Agreement End User is permitted to use the Santa Margarita Region Hydrology Model Software solely for purposes authorized by participating municipal county or special district member agencies of signatory programs which are organized on a county wide basis for implementation of stormwater discharge permits issued by the California Regional Water Quality Control Board under the National Pollutant Discharge Elimination System The End User is not permitted to use the Santa Margarita Region Hydrology Model Software for any other purpose than as described above End User shall not copy distribute alter or modify the Santa Margarita Region Hydrology Model Software The SMRHM incorporates data on soils climate and geographical features to support its intended uses of identifying site appropriate modeling parameters incorporating user defined inputs into long term hydrologic simulation models of areas within the County of Riverside and assisting design of facilities for flow duration control as described in the accompanying documentation These data may not be adequate for other purposes such as those requiring precise location measurement or description of geographical features or engineering analyses other than those described in the documentation This program and accompanying documentation are provided as is without warranty of any kind The entire risk regarding the performance and results of this program is assumed by End
136. ons n The infiltration reduction factor is a multiplier for the measured infiltration rate and should have a value of 1 00 or less Itis the same as the inverse of a safety factor For example a safety factor of 2 is equal to a reduction factor of 0 50 Infiltration occurs only through the bottom of the facility if the wetted surface area option is turned off Otherwise the entire wetted surface area is used for infiltration After the model is run and flow is routed through the infiltration facility the total volume infiltrated total volume through the riser total volume through the facility and percent infiltrated are reported on the screen If the percent infiltrated is 100 then there is no surface discharge from the facility The percent infiltrated can be less than 100 as long as the surface discharge does not exceed the flow duration criteria 66 Santa Margarita Region Hydrology Model Guidance June 2013 AUTO POND SMRHM pueumseow sHus _ a fol 3 trapezoidal Pond 4 mitigated Downstream Connections V Precipitation Appbed to Facility Iv Evaporation Applied to Facility Facility Dimensions Facility Bottom Elevation It Boltcen Length 1 Riser Diameter in p Bottom Width it Riser Type Fim EMHectrve Depth It Notch Type Predeveloped Bb Mitigated T Pond Depth finel 1 ft freeboard aji Pond length to width ratio 1 to 1 Volume sl reper head Choose Outlet Structure 1
137. orest shrub grass or urban Knowledge of the actual distribution of existing and proposed site topography by category flat moderate steep or very steep Knowledge of the planned distribution of the proposed development buildings streets sidewalks parking lawn areas overlying the soil categories Santa Margarita Region Hydrology Model Guidance June 2013 QUICK START Quick Start very briefly describes the steps to quickly size a stormwater detention pond using SMRHM New users should read the descriptions of the SMRHM screens elements and analysis tools before going through the steps described below 1 Open SMRHM SMRHM will open with a map of the Santa Margarita Region of Riverside County SMRHM File Edit View Help Summary Report Dc E see AASEN Os Suul e elg ESSI zl S Bo Santa Mar garita Santa Margarita y Site Information Site Name Address City Precip Factor E Map Controls aam Mp unns 3 7 2013 9 33 AM Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM File Edit View Help Summary Report O ze hl 5 cm A p Bl Site Information Site Name Address City Frecip Factor EE Map Controls sij ey 5 sahyetal Map The map controls can be used to enlarge a specific area on the street map layer This option helps to locate the specific project site When the street map layer 1s enlarged a sufficient amount the individua
138. orifice amp rectangular notch d 5 4 2013 205 PM Auto Pond automatically creates a pond size and designs the outlet structure to meet the flow duration criteria The user can either create a pond from scratch or optimize an existing pond design Auto Pond requires that the Predevelopment and Mitigated basins be defined prior to using Auto Pond Clicking on the Auto Pond button brings up the Auto Pond window and the associated Auto Pond controls Auto Pond controls Automatic Pond Adjuster The slider at the top of the Auto Pond window allows the user to decide how thoroughly the pond will be designed for efficiency The lowest setting 0 min at the left constructs an initial pond without checking the flow duration criteria The second setting to the right creates and sizes a pond to pass the flow duration criteria however the pond is not necessarily optimized The higher settings increase the amount of optimization The highest setting farthest right will size the most efficient smallest pond but will result in longer computational time 67 Santa Margarita Region Hydrology Model Guidance June 2013 Pond Depth Pond depth is the total depth of the pond and should include at least one foot of freeboard above the riser The pond s original depth will be used when optimizing an existing pond changing the value in the Pond Depth text box will override any previous set depth value The default depth 1s 4 feet Pond Len
139. orosity Quick Trench will instantly create a gravel trench bed with default values without checking it for compliancy with flow duration criteria Layer3 The gravel trench bed input information Bottom Width Trench Length ft Trench bed length 56 Santa Margarita Region Hydrology Model Guidance June 2013 Trench Bottom Width ft Trench bed bottom width Effective Total Depth ft Height from bottom of trench bed to top of riser plus at least 0 5 feet extra Bottom Slope of Trench ft ft Must be non zero Left Sideslope ft ft H V ratio of horizontal distance to vertical O zero for vertical trench bed sides Right Sideslope ft ft H V ratio of horizontal distance to vertical O zero for vertical trench bed sides Infiltration Rate in hr Trench bed gravel or other media infiltration rate Layer 1 Thickness ft Trench top media layer depth Layer 1 Porosity Trench top media porosity Layer 2 Thickness ft Trench middle media layer depth Layer 2 is optional Layer 2 Porosity Trench middle media porosity Layer 3 Thickness ft Trench bottom media layer depth Layer 3 1s optional Layer 3 Porosity Trench bottom media porosity Riser Height ft Height of trench overflow pipe above trench surface Riser Diameter 1n Trench overflow pipe diameter Riser Type options Flat or Notched Notch Type Rectangular V Notch or Sutro For a rectangular notch Notch Height feet distance from the top o
140. otch Type Orifice Diameter Height Number in ft m mo e a o iE Pond Volume at Riser Head ac ft D Show Pond Table OpenTable Initial Stage ft Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft Overflow Elevation ft fo Downstream Connection z lo Iterations p CA Imma 10 04 Abd The Point of Compliance screen will be shown for the pond The pond has one outlet by default The outflow from the pond will be compared with the Predevelopment runoff The point of compliance is designated as POC SMRHM allows for multiple points of compliance Click on the Connect button 16 SMRHM santa Margarita Region Hydrology Model Guidance June 2013 Eje Edit Wew Help ummary Report ss Bi Schematic Run Scenario Es Trapezoidal Pond 1 Mitipated ned BLU Outlet 1 f Downstream Connections Iv Precipitation Apobed to Facity Facility Dimensions Facility Bottom Elevation It eau ELI EE eli Bottom Length It Bottom Width It Effective Depth pit Left Side Slope HV Bottom Side Slope H V Right Side Slope HV Top Side Slope HA Infiltration ES cem Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate BEK ALE M A A Facility Type Trapezoidal Pond Outlet Z Outlet 3 Auto Pond Quick Pond Facility
141. ottom of a flow duration pond or the top layer of a bioretention facility However a safety factor 1s also used to account for uncertainties in the available estimate of in situ infiltration rates The SMMWW notes that its suggested CF values which range from 2 to 4 represent an average degree of long term facility maintenance TSS reduction through pretreatment and site variability in the subsurface conditions and that increases or decreases to these factors should be considered for unusual situations 161 Appendix C Santa Margarita Region Hydrology Model Guidance June 2013 Suggested safety factors in other texts and guidance generally range from 1 to 4 Santa Margarita Region County stormwater permits may require some form of tracking and verification for treatment and hydromodification facilities In addition designers should not be overly conservative in selecting a very high safety factor since this might lead to over controlled lower post project flows and an increase risk of causing impacts from deposition or sedimentation in the receiving channels In the absence of other guidance it is suggested that the SMRHM Infiltration Reduction Factor not be less than 0 25 or greater than 0 5 Note Santa Margarita Region County stormwater programs may also restrict the use of infiltration for treatment purposes in certain conditions since the flow duration facilities are also performing some treatment designers should discuss treatment
142. p gummary Report D Gk Xa pj oumE 0r oS Y MO ela E lll Schematic Low Impact Development Scenario Generator t xi TT 5 4 2013 447 PM The water balance chart graphically displays the runoff distribution for all four POCS side by side In the bar chart the bottom red 1s the surface runoff Above in yellow is interflow then green for groundwater and blue for evapotranspiration DMA 1 POC 1 is an A soil with grass land cover on a moderate slope and produces the least amount of surface runoff and interflow the sum of surface and interflow is the total stormwater runoff DMA 2 1s a C soil with shrub land cover on a moderate slope it produces more surface runoff and interflow than DMA 1 DMA 3 is a C soil with grass land cover on a moderate slope it produces more surface runoff and interflow than either DMA 1 or DMA 2 DMA 4 is a D soil with urban land cover on a moderate slope Urban land covers are irrigated Urban produces the largest amount of surface runoff and interflow in addition to a large amount of evapotranspiration due to the addition of irrigation water A maximum of seven scenarios can be graphed at one time 113 Santa Margarita Region Hydrology Model Guidance June 2013 OPTIONS Ele Edt yew Heb Summary Report HOLA PERE MM AAA OO Ju 3 7 Durstors Based on Use Defined Flow Values C AnakzeDunatonsto 0 Jes to 0 Jets Pate Fal threshold 11
143. r the Mitigated scenario DMA we will input the following information Pervious area e D soil e urban vegetation moderate slope 5 10 e 4 5 acres Impervious area s Roads moderate slope 2 5 acres Roof Area 1 5 acres Parking flat slope 1 5 acres The impervious land category includes roads roofs sidewalks parking driveways and any other impervious surfaces All are modeled the same the surface runoff produced from an impervious land surface only varies by land slope steeper slopes produce more runoff than flatter slopes The next step is to add a mitigation facility downstream of the DMA For this example we will use a trapezoidal stormwater pond also known as a detention basin to provide the required hydromod mitigation 11 SMRHM File Edit View Help Summary Report Dc EB 48 amp e se G e Commercial Toolbox Move Elements yo Save xy Load xy JE Santa Margarita Region Hydrology Model Guidance June 2013 EALE Or SO NA 5200 xt DMA 1 Mitigated Designate as Bypass for POC DMA Name Surface Flows To Area in Drainage Management Area Available Pervious Acres A Forest Flat 0 5 A Forest Mod 5 10 po AForest Stee 10 20 po Connect To Element Connect to Point Of Compliance Disconnect Element Disconnect POC Find Element Cut Element Copy Element Delete Element Duplicate Predeveloped Save Ele
144. ral watershed and stream processes by altering the terrain modifying the vegetation and soil characteristics introducing pavement and buildings installing drainage and flood control infrastructure and altering the condition of stream channels through straightening deepening and armoring These changes affect hydrologic characteristics in the watershed rainfall interception infiltration runoff and stream flows and affect the supply and transport of sediment in the stream system The change in runoff characteristics from a watershed caused by changes in land use conditions is called hydrograph modification or simply hydromodification As the total area of impervious surfaces increases in previously undeveloped areas infiltration of rainfall decreases causing more water to run off the surface as overland flow at a faster rate Storms that previously didn t produce runoff under rural conditions can produce erosive flows The increase in the volume of runoff and the length of time that erosive flows occur ultimately intensify sediment transport causing changes in sediment transport characteristics and the hydraulic geometry width depth slope of channels The larger runoff durations and volumes and the intensified erosion of streams can impair the beneficial uses of the stream channels Development of the Santa Margarita Region Hydrology Model The concept of designing a flow duration control facility is relatively new and as described above
145. recipitation gauge and precip factor are shown to the right of the map They are based on the project site location The user can provide site information optional The site name and address will help to identify the project on the Report screen and in the printed report provided to the local municipal permitting agency The user locates the project site on the map screen by using the mouse and left clicking at the project site location Right clicking on the map re centers the view The and buttons zoom 1n and out respectively The cross hair button zooms out to the full county view The arrow keys scroll the map view 36 Santa Margarita Region Hydrology Model Guidance June 2013 GENERAL PROJECT INFORMATION SCREEN SMRHM File Edit View Zoom Help Dc EB X8 amp MM Schematic Run Scenario PIERCE OSB ANH 100 00 e MEA Mitigated Oo 4 Flow Connections Drainage Elements ey lt 6 4 2013 12 54 PM The Project screen contains all of the information about the project site for the two land use scenarios Predevelopment land use conditions and Mitigated developed land use conditions To change from one scenario to another click on the tab containing the appropriate scenario name at the top of the grid Predevelopment is defined as the native land cover conditions prior to any land use development Runoff from the Predevelopment scenario is used as th
146. reen The basin information screen on the right will show that DMA 1 surface and interflow flows to Trapezoidal Pond 1 groundwater 1s not connected 89 Santa Margarita Region Hydrology Model Guidance June 2013 ANALYSIS SCREEN SARHM Examplet Ele Edit Wew Hep Summary Report Oca sme Aagsims Or Sa Be 0 oo 6 4 2013 46 PM The Analysis tool bar button third from the left brings up the Analysis screen where the user can look at the results of the Predevelopment and Mitigated scenarios The Analysis screen allows the user to analyze and compare flow durations flow frequency drawdown times hydrographs and LID BMP sizing by calculating Vgyp and Qgyp using the Rational Method 90 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM Example Dg DA MOTERO EM ANN RA 1ELSINORE EVAP emecula 22 IRRIGATION IN IHCHES 501 POC 1 Predeveloped Bow 701 Inflow to POC 1 Mitigated 3801 POC 1 Mibgated Hae Mi iapezodal Pond 1 STAGE Misgated Eana SEPH The user can analyze all time series datasets or just flow stage precipitation evaporation or point of compliance flows by selecting the appropriate tab below the list of the different datasets available for analysis 91 Santa Margarita Region Hydrology Model Guidance June 2013 FLOW DURATION SMRHM Example1 File Edit View Help Summary Report Duc E 39 museum Oe S B E amp D OD z Analysis The Facility PASSE
147. reshold flow frequency value 10 of the 2 year value to the upper threshold flow frequency value 10 year value As shown in the flow duration table to the right of the flow duration curves this flow range is divided into approximately 100 levels flow values The division of the flow range into a large number of levels is important to make sure that the erosive flows do not increase between the lower threshold 10 of the 2 year flow and the 2 year flow frequency value and between increasing flow frequency levels 3 year 4 year 5 year etc The majority of the erosive flows occur between the 10 of the 2 year flow value and the 2 year flow frequency value It is important to divide the flow levels in that range into multiple level steps to not miss any occasions when the mitigated flows exceed the predevelopment flows For each flow level value SMRHM counts the number of times that the flow at the Point of Compliance for the Predevelopment scenario Predev exceeds that specific flow level value It does the same count for the Mitigated scenario flow Mit The total number of counts is the number of simulated 15 minute time steps that the flow exceeds that specific flow level value 02 Santa Margarita Region Hydrology Model Guidance June 2013 The Percentage column is the ratio of the Dev count to the Predev count This ratio must be less than or equal to 100 for flow levels values between the lower threshold 10 of the 2 year f
148. rgarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank 156 Appendix B Santa Margarita Region Hydrology Model Guidance June 2013 APPENDIX B DEFAULT SMRHM HSPF IMPERVIOUS PARAMETER VALUES The default SMRHM HSPF impervious parameter values are found in SMRHM file defaultpersp uci HSPF parameter documentation is found in the document Bicknell B R J C Imhoff J L Kittle Jr T H Jobes and A S Donigian Jr 2001 Hydrological Simulation Program Fortran Users Manual for Version 12 AQUA TERRA Consultants Mountain View CA Table 1 SMRHM Impervious Land Types 2 Roads Moderate 5 10 3 1 Roads Steep 10 20 4 Roads VerySteep gt 20 6 Driveways Flat 0 5 7 Prveways Moderate 5 10 8 Driveways Steep 10 20 9 Driveways VerySteep gt 20 11 Sidewaks Moderate 5 10 12 Sidewalks Steep 10 20 13 Sidewalks VerySteep gt 20 14 Parking 16 Parking Parking Mery Steep gt 20 157 Appendix B Santa Margarita Region Hydrology Model Guidance June 2013 Table 2 SMRHM HSPF Impervious Parameter Values Part I IMPLND No SUR SLSUR NSUR RETSC 2 noo 010 pto pos 4 1 po p2s pio po 6 111 po pos pio 0 10 7 o 1 p00 010 pto pos 8 o poo 015 010 08 9 poo X 025 X010 06 11 100 pto pto O09 13 00 025 pto 060 15 00 pio pto po 16 17 gt oo P25 pto poe LSUR Leng
149. rlying native soil Measured Infiltration Rate in hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 69 Use Wetted Surface Area sidewalls Yes if infiltration through the tank sides is allowed If infiltration is used then the user should consult the Infiltration discussion on page 69 NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor A tank is covered and does not receive precipitation on and evaporation from the tank surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should not be checked 52 Santa Margarita Region Hydrology Model Guidance June 2013 IRREGULAR POND ELEMENT SMRHM Eje dt Wew Hep ummary Report Ill Schematic Im E irregular Pond 1 Mitigated x regda Pondi Facility Type Imega Pond Outlet 1 Outlet 2 Outlet 3 vaeumHos ausHuoc Downstream Connections MN Precipitation Applied to Faciity O Erpe Apoled oficij Facility Dimensions T Facility Bottom Elevation i e Outlet Structure ica i Rises Height ft 0 y Electes Devin Hi e oma Riser Diameter in mi Rise Type Ra 44 Hotch Type Orifice Diameter Height Number in ft le sijo cH 2b ZD 3 p fp Pond Volume at Fires He
150. s A fifth column can be used to create a second discharge cfs This second discharge can be infiltration or a second surface discharge 75 Santa Margarita Region Hydrology Model Guidance June 2013 Certain rules apply to the SSD Table whether it is created inside or outside of SMRHM These rules are Stage feet must start at zero and increase with each row The incremental increase does not have to be consistent Storage acre feet must start at zero and increase with each row Storage values should be physically based on the corresponding depth and surface area but SMRHM does not check externally generated storage values Discharge cfs must start at zero Discharge does not have to increase with each row It can stay constant or even decrease Discharge cannot be negative Discharge should be based on the outlet structure s physical dimensions and characteristics but SMRHM does not check externally generated discharge values Surface area acres is only used if precipitation to and evaporation from the facility are applied To input an externally generated SSD Table first create and save the table outside of SMRHM Use the Browse button to locate and load the file into SMRHM Santa Margarita Region Hydrology Model Eje fot yew Hep Summary Report BCA m ASUS Our Seek oc iH Schematic Run Scenario S ai Ta il el S el im Ed SSD Table 1 Mitigated Ed eloped Le Facilit
151. s allowed Underdrain Diameter inches and Height feet above bottom layer native soil interface The underdrain is optional Native Infiltration Yes infiltration into the underlying native soil Measured Infiltration Rate 1n hr Native soil infiltration rate Infiltration Reduction Factor 1 Native soil infiltration rate safety factor see page 69 If infiltration 1s used then the user should consult the Infiltration discussion on page 69 Any changes made by the user to the element dimensions and other input are not analyzed by SMRHM until the Run Scenario button is re clicked The Riverside County Design Handbook for Low Impact Development Best Management Practices specifies the following criteria for permeable pavement Max drawdown 24 hrs Max tributary area 10 ac Max reservoir gravel subgrade depth 1 ft Max pavement slope 0 03 Permeable pavement bottom slope zero Aggregate porosity 0 40 NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor 127 Santa Margarita Region Hydrology Model Guidance June 2013 BIORETENTION STANDARD DESIGN 6 MINIMUM TOP WIDTH 1 i RM Ni T i gt 0 ae DEPTH X SIDE SLOPE 2 MINIMUM DEPTH X SIDE SLOPE PONA EQUIVALENT DROP INLET PONDING DEPTH GRAVEL PAD 6 MAXIMUM PARKING OR DRIVE AISLE TY SLO
152. s are Infiltration Basin Infiltration Trench Permeable Pavement Bioretention standard design Bioretention vertical sideslopes Bioretention planter box sand Filter Extended Detention Basin MIS mS UE Each of these eight LID BMPs are described below NOTE Many of these LID BMP practices and facilities rely on infiltration into native soils See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of an infiltration reduction factor where appropriate 118 Santa Margarita Region Hydrology Model Guidance June 2013 INFIL TRATION BASIN POND Concrete impact wall berm with weir s Overflow Outlet offset from inlet Per District Standard Drawing Concrete CB 110 or similar forebay Maintenance acces Either CB 110 overflow PLAN outlet or emergency oa spillway may be used Pipe inlet at embankment Concrete impact wall with full height weir s Water surface at Vamp Flat basin floor 2 L 1 min with native grass MON D LILI E g LA G N 4 LA 4 x G 4 k ES AS SK SL SSEFESDEGDSGEES VR TIRED Figure courtesy of Riverside County Flood Control and Water Conservation District An infiltration basin allows stormwater to enter the basin above ground and then infiltrate through the bottom of the basin into the native soil beneath the basin Overflow is controlled by an overflow outlet
153. s requires approval by the local municipal permitting agency or Appendix C Click on the Update button once all of the changes have been made To return to the default values click on the Restore Defaults button 116 Santa Margarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank 117 Santa Margarita Region Hydrology Model Guidance June 2013 TIPS AND TRICKS FOR LID PRACTICES AND FACILITIES There are many different tips and tricks that can be used to tailor SMRHM to solve different stormwater problems This section presents only a fraction of the tricks that we and others have found and used but it should give you a good idea of the options and flexibility built into SMRHM The tips and tricks show how different LID BMPs Low Impact Developments Best Management Practices can be represented by SMRHM elements LID BMP practices and facilities reduce the need for and the size of stormwater control facilities LID BMP practices and facilities typically try to mimic the natural environment and provide source control and storage of runoff Riverside County s Design Handbook for Low Impact Development Best Management Practices September 2011 include eight 8 practices that can be modeled using the comparable SMRHM elements This handbook has the most up to date information regarding BMP standards and should be consulted prior to the start of any SMRHM LID BMP modeling The eight LID BMP
154. scenario and then S the Mitigated scenario Left click on the Land use Basin element under the ED Drainage Elements heading The Land use Basin element represents a drainage management area aan DMA SEO Select any grid cell preferably near the top of the grid and left click on that grid The DMA will appear in that grid cell Save xy Load xy LE xi T a SMRHM Eje E Mew Help Summary Report Deh Da Le le s ST e m Schematic Predeveloped P Miligat Run lm santa Margarita Region Hydrology Model Guidance June 2013 E DMA 1 Predeveloped DMA Name Flows To Surface Intesflows Groundwater Area in Drainage Management rea Show Only Selected al A amp Faonest Arnes bo E AE B M Asme J ETT B a pI M Aereo 5 Aiba Fas ADR Mas M Alcan Se 8 E s e ieee Available Pervious Acres AFeesFi5x Available im ervious Acres a RoadzFla D 5 r Roads Modi5 10x F ees Ems 0 ETT 5 r Poing Step M Fda 5 4 2013 817 AM To the right of the grid 1s the land use information associated with the DMA Select the appropriate soil land cover and land slope for the Predevelopment scenario Soils are based on NRCS general categories A B C and D Land cover is b
155. se over the grid to locate the pond s corner points The user does this in a clockwise direction to outline the pond s top perimeter The user can select individual points by clicking on the point button immediately below the line button Once selected any individual point can be moved or repositioned m PondPad PondPad E Grid Scale ft Set Area 12206 186 Grid Scale ft Set Area 12220 013 sq ft Grid X 5i Je Slope dA 1 Grid X 62 Slope Em 1 Grid Y mn Grid Y eo jt Santa Margarita Region Hydrology Model Guidance June 2013 The default sideslope value is 3 3 1 The sideslopes can be individually changed by right clicking on the specific side which changes the line color from black to red and then entering the individual sideslope value in the slope text box The grid scale can be changed by entering a new value in the grid scale box The default value 1s 200 feet PondPad Controls and Numbers Clear The Clear button clears all of the lines on the grid Line The Line button allows the user to draw new lines with the mouse Point The Point button allows the user to move individual points to alter the pond shape and size Sq Ft Converts the computed pond area from square feet to acres and back Grid Scale Changes the length of a grid line Default grid scale is 200 feet Grid X Horizontal location of the mouse pointer on th
156. sea fect 000 Show Splitter Table Open Table 24 Initial Stage It p 1 5 4 2013 310 PM The second option is that the flow split can be based on a flow threshold The user sets the flow threshold value cfs for exit 1 at which flows in excess of the threshold go to exit 2 For example if the flow threshold is set to 5 cfs then all flows less than or equal o 5 cfs go to exit 1 Exit 2 gets only the excess flow above the 5 cfs threshold total flow minus exit 1 flow 72 Santa Margarita Region Hydrology Model Guidance June 2013 TIME SERIES ELEMENT SMRHM Ele Edit Yew Hep Summary Report els E isl st Time Series 1 Mitigated pj oHumHovs5HUuHBuo developed Hitigated 1 ELSINORE EVAP 2 Temecula Valley di IRRIGATION IN INCHES UI Indio to PUL T Miboaded 801 POC 1 Mitgated flow 1000 Channel 1 ALL OUTLETS Mibgated 1001 Channel 1 STAGE Miigated spercidal Pond 1 ALL OUTLETS Mitiga re 5 4 2013 315 PM SMRHM uses time series of precipitation evaporation and runoff stored in its database HSPF WDM file The user has the option to create or use a time series file external from SMRHM in SMRHM This may be a time series of flow values created by another HSPF model An example is offsite runoff entering a project site If this offsite runoff is in an existing WDM file and is the same period as SMRHM data and the same simulation time step 15 minute then it can be linked to SMRHM model using
157. sion on page 69 NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor A vault is usually covered and does not receive precipitation on and evaporation from the vault surface The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should not be checked unless the vault top is open to the atmosphere 50 Santa Margarita Region Hydrology Model Guidance June 2013 TANK ELEMENT SMRHM ALTA MAA o E Schematic a Le Ir si Tank 1 Mitipated X Pr Taki Facility Type Tank developed Miliqated Outlet 1 Outlet 2 Outlet 3 Downstream Connection AM Precipitation Applied to Facsiy Auto Tank QOuickTank Evaporation Appied to Facit Facility Dimension Diagram _ Facility Dimensions Outlet Structure Data Facility Bottom Elevation It Pl ee po Tank Type Cece ian DN W b nsi Diameter t o SC sn SD H Length 9 NN S 5 ee Notch Type Orifice Diameter Height Number in tt ib ih 4 2 lp Jl ap Tank Volume al Aie Head sci Show Tank Table DpenTabe initial Stage If Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation D Downstream Connection e Overflow Elevation ft fo Meratons
158. t model the bioretention both ways and see how close the simple swale answer is to the standard swale method The standard swale method will always be more accurate than the simple swale 84 Santa Margarita Region Hydrology Model Guidance June 2013 POINT OF COMPLIANCE SMRHM allows for multiple points of compliance maximum of 59 in a single project A point of compliance is defined as the location at which the Predevelopment and Mitigated flows will be analyzed for compliance with the flow control standard Santa Margarita Region Hydrology Model File Edit View Help Summary Report D c E X Bs MASAH HEH Ose BAR iu ooo MM Schematic In X i Trapezoidal Pond 1 Mitigated Lill Predeveloped MITE mm Facility Name Trapezoidal Pond 1 Facility Type Trapezoidal Pond Run mane Outlet 1 Outlet 2 Outlet 3 Scenario Downstream Connections l v Precipitation Applied to Facility Auto Pond Quick Pond Drainage Elements V Evaporation Applied to Facility Facility Dimension Diagram Facility Dimensions Outlet Structure Data Facility Bottom Elevation ft fs Riser Height ft o Bottom Langh ft po Riser Diameter in p Bottom width ft po Riser Type Flat sl Effective Depth ft fs Moleh Tues Left Side Slope H v po Bottom Side Slope HV fs Right Side Slope HV po UT seen Ad pS Orifice Diameter Height TE a Infiltration No Number in ft EM Point Of Co
159. t provides base flow directly to streams and rivers The user can specify where each of these three types of runoff should be directed The default setting is for the surface runoff and interflow to go to the stormwater facility groundwater should not be connected unless there 1s observed base flow occurring in the DMA 40 Santa Margarita Region Hydrology Model Guidance June 2013 Table 1 shows the different pervious land types represented in the Land use Basin element Table 1 SMRHM Pervious Land Types 1 A Forest Flat 0 5 A Foret X Moderate 5 10 A Forest Steep 10 20 a Very Steep gt 20 Flat 0 5 Moderate 5 10 Steep 10 20 Very Steep gt 20 9 OA Qgras fFlat 0 5 10 A Grass Moderate 5 109 H Rh ass Steep 10 20 122 gt A Grass Nery Steep gt 20 Bo Hen Fatos ja RA an Moderate 5 10 6 ZAJ tm Steep 10 20 16 Arba vey RE gt 20 E B pes Fabia B oes Moderate B 10 B oet Steep 10 20 B Forest yerySteep 2072 B Shrub fFlat 0 5 B 1 gShub Moderate 5 10 B B gf Steep 10 20 Very Steep gt 20 B Gras lat 0 5 B Gras Moderate 5 10 Grass Steep 10 20 B Gras ven Steep gt 20 B_ Urn Flat 0 5 B _ Urban Moderate 5 10 B Uran y 10 a E o Ses gt 20 cD forest A LA E 10 E A Steep 10 20 86 1 CD X Forest Very Steep gt 20 38
160. table for the pond 19 Santa Margarita Region Hydrology Model Guidance June 2013 With this initial pond stage storage discharge table SMRHM l routes the 15 minute post project runoff through the pond for the 30 50 years of record to create the Mitigated flow time series 2 counts the number of 15 minute Mitigated flow values that exceed each flow increment level this 1s the Mitigated flow duration and 3 computes the ratio of Mitigated flow values to Predevelopment flow values for each flow increment level comparing the Predevelopment and Mitigated flow duration results If any of the 100 individual ratio values is greater than allowed by the flow duration criteria then the pond fails to provide an appropriate amount of mitigation and needs to be resized SMBHM Eje dt Wew Hep ummary Report DS id DA zueumHioows5ssmSu HERAS A E Schematic aag Predeveloped LITA 2 JFaciityName Facility Type Run Outlet 1 Outlet 2 Outlet 3 scone Downstream Connections EJ V Precision Acc to Fac QuckPond v Evaporation Applied to Facdity Facility Dimension Diagram Facility Dimensions utlet Structure Data Facility Bottom Elevation It A E Dramage Elements n T T dll 2 10 min gt 10 min Fast Thorough Pond Depth incl 1 ft freeboard 4 ft Pond length to width ratio 1 ta1 Pond Side Slopes 3 to 1 Bottom Length 184583499 ft
161. tage ft O Target 100 E Move Elements mE EF xm ME lt 6 5 2013 2 50 PM The trapezoidal pond dimensions and parameters to adjust to represent the forebay are discussed on page 46 The irregular pond dimensions and parameters to adjust to represent the forebay are discussed on page 56 The gravel trench dimensions and parameters to adjust to represent the connector trench are discussed on page 59 The sand filter dimensions and parameters to adjust to represent the filter drain are discussed on page 61 The SSD element is discussed on page 78 The Riverside County Design Handbook for Low Impact Development Best Management Practices specifies the following criteria for the extended detention basin 137 Min tributary area 5 ac Max drawdown 72 hrs Max Sideslope 4 to 1 Trench bottom slope 1 Min filter drain depth 2 33 ft Santa Margarita Region Hydrology Model Guidance June 2013 138 Santa Margarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank 139 Appendix A Santa Margarita Region Hydrology Model Guidance June 2013 APPENDIX A DEFAULT SMRHM HSPF PERVIOUS PARAMETER VALUES The default SMRHM HSPF pervious parameter values are found in SMRHM file defaultpersp uci HSPF parameter documentation is found in the document Bicknell B R J C Imhoff J L Kittle Jr T H Jobes and A S Donigian Jr 2001 Hy
162. th of surface flow path feet for impervious area SLSUR Slope of surface flow path feet feet for impervious area NSUR Surface roughness Manning s n for 1mpervious area RETSC Surface retention storage inches for impervious area 158 Appendix B Santa Margarita Region Hydrology Model Guidance June 2013 Table 3 SMRHM HSPF Impervious Parameter Values Part II IMPLND No RETS SURS 1 po po RETS Initial surface retention storage inches for impervious area SURS Initial surface runoff inches for impervious area 159 Appendix B Santa Margarita Region Hydrology Model Guidance June 2013 This page has been intentionally left blank 160 Appendix C Santa Margarita Region Hydrology Model Guidance June 2013 APPENDIX C ADDITIONAL GUIDANCE FOR USING SMRHM Scope and Purpose This appendix includes guidance and background information that are not incorporated into the SMRHM software but which the user needs to know in order to use SMRHM for designing projects in the participating jurisdictions The three main topic areas in this appendix are flagged in the main guidance documentation text by specially formatted notes under the SMRHM elements or software features to which they are related Appendix C Topic Relevant Sections in Guidance documentation Infiltration Reduction Factor Infiltration page 69 applicable when specifying characteristics of a facility pond vault tank some LID elements if
163. th orifices and or notches protected by racks or gratings This may be fabricated from a large steel plate similar in construction to the extended detention outlets specified in the Denver Colorado manual referenced below This alternative outlet can be simulated in the SMRHM as a very large diameter standpipe where the width of the top notch is equal to the overflow width at the top of the plate between its supports Drawdown time and treatment vector considerations Flow duration control facilities are designed to detain stormwater onsite for an extended period of time The drawdown time is a concern to designers in relation to three areas of design besides hydromodification management l Standing water for extended periods provides a potential habitat in which mosquitoes can breed Riverside stormwater programs work with their local mosquito abatement or vector control agencies to develop guidelines for stormwater facility design these generally recommend that design detention times not exceed 96 hours Provisions for access and inspection by vector control personnel are also required Contact the local permitting agency for details of local vector control provisions which apply to both treatment measures and flow duration facilities 2 Stormwater that is detained also undergoes water quality treatment through settling and or infiltration of pollutants The focus of water quality management is reducing mean annual loads and typical conc
164. top of pavement plus at least 0 5 feet extra Bottom Slope ft ft Pavement slope or grade Effective Volume Factor zero unless the bottom slope is greater than 2 The effective volume factor is a value between zero and 1 00 It is only used when the bottom slope is greater than 2 The effective volume factor is the fraction ratio of the average maximum water depth behind a check dam in the gravel layer Sublayer 1 compared to the maximum gravel layer depth Sublayer 1 For example if the average maximum water height is 6 and the gravel depth is 9 then the Effective Volume Factor 0 67 6 9 The effective volume factor is multiplied by the Sublayer 1 storage volume to determine the actual maximum volume available for stormwater storage before the check dam is overtopped and the water in the gravel layer depth Sublayer 1 proceeds to a downstream conveyance facility Pavement Thickness ft Permeable pavement layer depth Pavement Porosity Permeable pavement porosity Sublayer 1 Thickness ft Subgrade gravel layer depth 126 Santa Margarita Region Hydrology Model Guidance June 2013 Sublayer 1 Porosity Subgrade gravel porosity Sublayer 2 Thickness ft Sand layer depth 1f appropriate Sublayer 2 Porosity Sand porosity Ponding Depth above Pavement ft Height at which surface runoff occurs NOTE Check with Appendix C or the local municipal permitting agency to find out If ponding on the surface of the pavement i
165. tor 1 Native soil infiltration rate safety factor see page 69 Use Wetted Surface Area sidewalls Yes if infiltration through the basin sideslopes is allowed If infiltration is used then the user should consult the Infiltration discussion on page 69 120 Santa Margarita Region Hydrology Model Guidance June 2013 Any changes made by the user to the element dimensions and other input are not analyzed by SMRHM until the Run Scenario button is reclicked The Riverside County Design Handbook for Low Impact Development Best Management Practices specifies the following criteria for infiltration basins Maximum drawdown time 72 hrs Maximum tributary area 50 ac Maximum depth 5 ft Maximum sideslopes 4 to 1 NOTE See Appendix C or consult with the local municipal permitting agency for additional considerations regarding infiltration and determination of the appropriate infiltration reduction factor An infiltration basin pond receives precipitation on and evaporation from the basin surface area The Precipitation Applied to Facility and Evaporation Applied to Facility boxes should be checked 121 Santa Margarita Region Hydrology Model Guidance June 2013 INFILTRATION TRENCH NOCURB PREFERRED IFREQUIRED MUST BE SLOTTED OBSERVATION WHEEL WELL WITH PARKING STOPS REMOVEABLE CAP LOT SCREENED FILTER STRIP OVERFLOW FILTER TRIP LAYER D SO Varo i DEPTH DEPTHOF RESERVOIR CR DE BM TOTAL TRENCH
166. uired for a project site 1t 1s recommended that the design process start by using SMRHM to obtain a preliminary design for the flow duration pond vault or tank Then check the performance of the facility for vector control concerns and against treatment and or flood control design criteria as appropriate The latter are both based on the concept of a single empirical design storm which does not directly correspond to the flow duration approach using frequency analysis in a long term simulation Stormwater treatment design requires the use of volume based runoff coefficients which although similar in concept to runoff coefficients used for flood control are determined differently Runoff coefficients used for flood control were derived for large storms with some conservatism built in to estimates of peak flow rates and water surface elevations Runoff coefficients for stormwater treatment have been adjusted to reflect runoff from small storms where a greater percentage of the rainfall is held within the catchment Vector Management If the maximum allowed drawdown 1s seldom or never exceeded over the simulation period then likelihood of mosquito breeding in the facility 1s very low and the design for the pond vault or tank does not need to be modified If a maximum allowed drawdown time is exceeded then the system may need to be redesigned to reduce the drawdown time The designer should consider additional reductions in impervious area and or LI
167. ume at Top of Storage wea fach Show Splitter Table Initial Stage It Macamum Depth of Ponding ft Secondary Exit 2 Structure Control Stucture HA Rise Height H fo so Ree Dismetes in p H Rise Type Fu Onfice Diameter Height in ft p mi ep db 4 sip O 28 OpenTable 2 5 4 2013 3 08 PM The flow splitter divides the runoff and sends it to two different destinations The splitter has a primary exit exit 1 and a secondary exit exit 2 The user defines how the flow is split between these two exits The user can define a flow control structure with a riser and from one to three orifices for each exit The flow control structure works the same way as the pond outlet structure with the user setting the riser height and diameter the riser weir type flat rectangular notch V notch or Sutro and the orifice diameter and height For more information on riser notch options and orifices see discussion in OUTLET STRUCTURE CONFIGURATIONS section 71 Santa Margarita Region Hydrology Model Guidance June 2013 SMRHM m E Mew Helo gummary Report letele t S en Ill Schematic ml EJ sl Flow Splitter 1 Mitigated 3 e Facility Name o Downstream Connection Both Exits Primary Exfl Secondary Exif Trapezoidal Pond 1 Channel 1 Upzhream uns dii Length ft ESL EXT Suviiure Secondary Exit 2 Structure Flow Threshold Flow Threshold cts s Volume a Top ol Storage
168. xceeds the surface outlet s storage Runoff in both the surface storage and amended soil storage is available for evapotranspiration Surface storage evapotranspiration is set to the potential evapotranspiration the amended soil evapotranspiration pan evaporation factor is set to 0 50 to reflect reduced evapotranspiration from the amended soil In the amended soil water movement through the soil column is dependent on soil layer characteristics and saturation rates for different discharge conditions Consider a simple two layered bioretention facility designed with two soil layers with different characteristics As water enters the facility at the top it infiltrates into the soil based on the modified Green Ampt equation Equation 1 The water then moves through the top soil layer at the computed rate determined by Darcy s and Van Genuchten s equations As the soil approaches field capacity 1 e gravity head is greater than matric head we can determine when water will begin to infiltrate into the second layer lower layer of the soil column This occurs when the matric head is less than the gravity head in the first layer top layer 172 Appendix E Santa Margarita Region Hydrology Model Guidance June 2013 Since the two layers have different soil characteristics water will move through the two layers at different rates Once both layers have achieved field capacity then the layer that first becomes saturated 1s determined by which
169. y Load xy Sl s DeselectZero Select By GO 5 4 2013 3 38 PM Elements are connected by right clicking on the upstream element 1n this example DMA 1 and selecting and then left clicking on the Connect To Element option By doing so SMRHM extends a line from the upstream element to wherever the user wants to connect that element 87 Santa Margarita Region Hydrology Model Guidance June 2013 Santa Margarita Region Hydrology Model File Edit View Help Summary Report Dac E X we i musSumemM OuwaoDiuiJuloo A Grass Mod 5 10 A Urban Flat 0 5 o ii reses CONS F Ill Schematic ax DMA 1 Mitigated BUT Predeveloped IOTZ DMA Name Designate as Bypass for POC Scenario Surface Interflow Groundwater Flows To a Area in Drainage Management Area Show Only Selected Available Pervious Acres Available Impervious Acres a A Forest Flat 0 5 a Roads Flat 0 5 I A Forest Mod 5 10 D Reads Mod 5 10z po B Forest Flat 0 5 o Parking Very gt 20 po I B Forest Mod 5 10 Dp jJ Pond Area po Ss r BForestSteei020 p Move pu PerviousT otal PO O Acres Impervious Total Acres e 4 p PO DMA Total PO O Acres S y Load x ee DE Bly Rn it uim JE vi 44 70012 2 20 DH The user extends the connection line to the downstream element in this example a pond and left clicks on the
170. y Name 550 Table 1 Flows To I Precipialion A Evaporation Appked Facility Type55D TABLE Manual initiation Load File Browse P Not Used Manual Outlet Structure Tide Gate Time Series Demand Determine Outlet With Tide Gate Use Tide Gate Tide Gate Elevation ft 0 Downstream Connection Overflow Elevation ff jo Meretons b 8 rt initial Stage ft fo 544 2013 3 20PM 76 Santa Margarita Region Hydrology Model Guidance June 2013 The first three columns Stage Area Storage will automatically show in the table To use the additional columns Column 4 5 etc click on the Not Used at the head of the table and select the appropriate option For externally calculated discharge cfs select Manual in Column 4 To have SMRHM calculate discharge based on outlet structure dimensions select Outlet Structure If infiltration is included then click on Not Used in Column 5 and select the appropriate option TI Santa Margarita Region Hydrology Model Guidance June 2013 BIORETENTION ELEMENT Santa Margarita Region Hydrology Model Ele Edit Wew Heb gummaryReport Dc b tha pjuseumm ws ele E SS ol MM Schematic A im x si Bio Swale 1 Mitipated ed P Facility Name Outlet 1 Downstream Connection Facility Type Bioretention Swale Use simple swale Default Swale Underdrain Used Swale Bottom Elevation ft Swale Dimensions Flow Through
171. y Type Use simple swale Default Swale Underdrain Used Swale Bottom Elevation ft Swale Dimensions Swale Length It Svale Bottom width H Freeboard It Oversoad Flooding li wy p Elfecive Total Depth Il Verica Once Ovediow H Bottom slope of Swata ft Outlet Configuration Data Top and Bottom side slope it oo Vertical Orifice diameter in Left Side Slope HV Vertical Orifice Elevation in Width of overroad flow ft Material Layers for Swale Layer Layer Laer 3 Edit amp ail Types KSat Safety Factor E Nona 02 ra Show Swale Table Open Table Swabs Volume at Are Head ac ft Native Infiltration No 6 4 2013 3 27 PM The input information required for the vertical orifice plus overflow is Vertical Orifice Diameter inches diameter of vertical opening below the weir Vertical Orifice Elevation inches vertical distance from the top of the amended soil surface to the bottom of the vertical orifice Width of Over road Flow feet weir street length Diagram of bioretention with vertical orifice plus overflow 80 Santa Margarita Region Hydrology Model Guidance June 2013 Width of Over road Flow Over road Flooding Freeboard Native Soil O Vertical Orifice Diameter Vertical Orifice Elevation Effective Total Underdrain Native Soil Native Soil Riser outlet structure option Santa Margarita Region Hydrology Model Fle Edt
172. ydrologic effects of land development activities that result from soil compaction when Urban is specified The impervious land category includes roads roofs sidewalks parking driveways and any other impervious surfaces All are modeled the same the surface runoff produced from an impervious land surface only varies by land slope steeper slopes produce more runoff than flatter slopes 42 Santa Margarita Region Hydrology Model Guidance June 2013 LATERAL BASIN ELEMENT Pervious SMRHM Ele Edit Wew Help Summary Report Dc IDA EMPERO MM AAA BG lt sele ENEJ Bl Schematic E x Y Lateral Basin 1 Predeveloped x Element Name Lo nisl Mitigated Run 2 E Runoff Type Scenario Downstream Connection Element Type Lateral Pervious Flow Basin al Lateral Barin 1 Surface Interflow Groundwater Change fici A Forest Flaij 5 A Foret Mod 5 10 A Forest Stee 10 20 A Foret Very 20 A Shub Flan 55 A Shrub Mod 5 105 A Shub Stee 10 20 A Shrub Very S AE A Brass Flas 0 5 5 4 2013 1 01 PM Runoff dispersion from impervious surfaces onto adjacent pervious land can be modeled using pervious and impervious lateral basins For example runoff from an impervious parking lot can sheet flow onto an adjacent lawn prior to draining into a stormwater conveyance system This action slows the runoff and allows for some limited infiltration into the pervious lawn s
173. yes is selected as the Infiltration option Flow Duration Outlet Structures Outlet Structure Configurations pages 63 65 includes sizing of low flow orifice and applicable when specifying characteristics of a flow alternative configurations duration facility Drawdown drain time for flow duration Drawdown Analysis screen page 98 facilities This guidance was originally created by the stormwater programs of Alameda Santa Clara and San Mateo Counties Please consult with the local municipal permitting agency for additional considerations Additional guidance and references are also discussed at the end of this appendix infiltration Reduction Factor The Western Washington Hydrology Model included this factor to reflect the requirement in the Stormwater Management Manual for Western Washington SMMWW to incorporate a Correction Factor CF to determine long term infiltration rates the inverse of the CF is the Infiltration Reduction Factor in SMRHM The SMMWW gives three methods for determining CF 1 a table providing empirical correlations between long term infiltration rates and USDA Soil Textural Classification 2 ASTM gradation testing at full scale infiltration facilities or 3 In situ infiltration tests preferably using a Pilot Infiltration Test specified in an appendix of the SMMWW Application of a CF or safety factor attempts to account for clogging and the reduction in infiltration over time which might apply to the b

WWHM3 User Manual - Riverside County Flood Control

Contents

Download Pdf Manuals

Related Search

Related Contents