Stormwater Source Control Design Guidelines 2005 - Waterbucket

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DESIGN PRINCIPLES■ Literature suggests swale areas ofabout 10-20% of upstream imperviousarea. For GVRD, calculate swale areaby continuous flow modelling.2% SLOPE2.0% SLOPELEVEL BASE (TYP)10m MAXTRENCH DAM OF COMPACTEDNATIVEMATERIAL OR EQUIVALENT TO CREATESUBSURFACE BASIN2.0% SLOPE10m MAXWEIR5%SLOPE SLOPE2.0% SLOPE10%2.0%2.0%2.0%5m MAXOUTLET TO PIPE SYSTEM ORWATERCOURSE2.0%2.0%■ Flow to the swale should bedistributed sheet flow, travellingthrough a grassy filter area at theswale verges. Provide pre-treatmentand erosion control to avoidsedimentation in the swale.■ Provide a 25mm drop at the edge ofpaving to the swale soil surface, toallow for positive drainage andbuildup of road sanding/organicmaterials at this edge.■ Swale planting is typically soddedlawn. Low volume swales can befinished with a combination ofgrasses, shrub, groundcover and treeplanting.■ Swale bottom - flat cross section, 600to 2400mm width, 1-2% longitudinalslope or dished between weirs.■ Swale side slopes -3(horizontal):1(vertical) maximum, 4:1preferred for maintenance.■ Weirs to have level top to spreadflows and avoid channelization, keyedin 100mm minimum.■ Maximum ponding level - 150mm.Drawdown time for the maximumsurface ponded volume - 24 hours.ADJACENT GRADERETENTIO7PLAN123481236 4PROVIDE EROSION CONTROLALONG SIDES OF WEIR ANDAT DRAINAGE INLETSCONCRETE WEIRAn Infiltration Swale is a shallow grassedor vegetated channel designed to capture,detain and treat stormwater and conveylarger flows. It takes surface flows fromadjacent paved surfaces, holds the waterbehind weirs, and allows it to infiltrate througha soil bed into underlying soils. The swaleand weir structures provide conveyance forlarger storm events to the storm drainsystem. Variations on designs include anunderlying drain rock reservoir, with orwithout a perforated underdrain.Full InfiltrationWhere water entering the swale is filteredthrough a grass or groundcover layer, andthen passes through sandy growing mediumand a sand layer into underlying scarifiedsubgrade. Suitable for sites with smallcatchments and subsoil permeability> 30mm/hr.Full Infiltration with ReservoirDesigned to reduce surface ponding byproviding underground storage in a drain rockreservoir. Suitable for sites with smallcatchments and subsoil permeability> 15mm/hr.■ Treatment soil depth - 450mmdesirable, minimum 150mm if designprofessional calculates adequatepollutant removal.■ Design stormwater conveyance usingManning’s formula or weir equationswhichever governs with attention tochannel stability during maximumflows.■ Drain rock reservoir and underdrainmay be avoided where infiltrationtests by a qualified professional,taken at the depth of the proposedinfiltration, show an infiltration ratethat exceeds the inflow rate.751236 41. Weir Keyed into Swale Side Slope2. Growing Medium (300mm Min.)3. Sand4. Existing Scarified Subsoil88Partial Infiltration withReservoir and SubdrainWhere a perforated drain pipe is installed atthe top of the reservoir, providing anunderground overflow that removes excesswater before it backs up to the surface of theswale. Suitable for sites with largercatchments and low infiltration rates intosubsoil permeability < 15mm/hr. Provideswater quality treatment even if infiltration intosubsoils is limited.5. Perforated Underdrain (150mm Dia. Min.)6. Drain Rock Reservoir (300mm Min.)7. Geotextile Along All Sides of Reservoir8. Trench Dams at All Utility CrossingInfiltration Swale SystemGreaterVancouverRegionalDistrictStormwater Source Control Design Guidelines 2005Goya NganLandscape ArchitectDetailed design guidelines can be found in the DesignGuidelines 2005 report, available at www.gvrd.bc.ca11
DESIGN PRINCIPLES■ Literature suggests rain garden areasof about 10-20% of upstreamimpervious area. For GVRD, calculaterain garden area by continuous flowmodelling. Optimum rain garden sizeis about 50sq.m. draining 250sq.m. ofimpervious area.■ Smaller, distributed rain gardens arebetter than single large scale facilities.■ Locate rain gardens a minimum 30.5mfrom wells, 3m downslope of buildingfoundations, and only in areas wherefoundations have footing drains andare not above steep slopes.■ Provide pretreatment and erosioncontrol i.e. grass filter strip to avoidintroducing sediment into the garden.■ At point-source inlets, installnon-erodable material, sedimentcleanout basins, and weir flowspreaders.■ Bottom width - 600mm (Min.) to3000mm (desirable). Length-widthratio of 2:1.■ Side slopes - 2:1 maximum, 4:1preferred for maintenance.Maximum ponded level - 150 -300mm.■ Draw-down time for maximum pondedvolume - 72 hours.■ Treatment soil depth - 450mm (Min.)to 1200mm (desirable); use soils withminimum infiltration rate of 13mm/hr.■ Surface planting should be primarilytrees, shrubs, and groundcovers, withplanting designs respecting thevarious soil moisture conditions in thegarden. Plantings may include rushes,sedges and grasses as well as lawnareas for erosion control and multipleuses.■ Apply a 50-75mm layer of organicmulch for both erosion control and tomaintain infiltration capacity.An Infiltration Rain Garden is a form of bioretention facility designed to have aesthetic appealas well as a stormwater function. Rain gardens are commonly a concave landscaped area whererunoff from roofs or paving infiltrates into deep constructed soils and subsoils below. On subsoilswith low infiltration rates, Rain Gardens often have a drain rock reservoir and perforated drainsystem to convey away excess water.1. Tree, Shrub and Groundcover Plantings2. Growing Medium Minimum 450mm Depth3. Drain Rock Reservoir4. Flat Subsoil - scarified5. Perforated Drain Pipe 150mm Dia. Min.6. Geotextile Along All Sides of Drain Rock Reservoir7. Overflow (standpipe or swale)8. Flow Restrictor Assembly9. Secondary Overflow Inlet at Catch Basin10. Outflow Pipe to Storm Drain or Swale System11. Trench Dams at All Utility CrossingsFull InfiltrationWhere all inflow is intended to infiltrate into theunderlying subsoil. Candidate in sites withsubsoil permeability > 30mm/hr. An overflow forlarge events is provided by pipe or swale to thestorm drain system.Full Infiltration with ReservoirAdding a drain rock reservoir so that surfacewater can move quickly through the installedgrowing medium and infiltrate slowly into subsoilsfrom the reservoir below. Candidate in sites withsubsoil permeability > 15mm/hr.Partial InfiltrationDesigned so that most water may infiltrate intothe underlying soil while the surplus overflow isdrained by perforated pipes that are placed nearthe top of the drain rock reservoir. Suitable forsites with subsoil permeability > 1 and
Page 1 and 2: Stormwater Source ControlDesign Gui
Page 3 and 4: Contents Stormwater Source Control
Page 5 and 6: Acknowledgements Stormwater Source
Page 7 and 8: Introduction Stormwater Source Cont
Page 13 and 14: Summary Posters Stormwater Source C
Page 15: DESIGN PRINCIPLES■ Maximize the a
Page 19 and 20: DESIGN PRINCIPLES■ Suitable for f
Page 23 and 24: Rainwater Source Control Around the
Page 29 and 30: Absorbent Landscape Stormwater Sour
Page 39 and 40: Infiltration Swale Stormwater Sourc
Page 43 and 44: FLOWGROWING MEDIUMADJACENT GRADE200
Page 45 and 46: FLOWADJACENT GRADE200GROWING MEDIUM
Page 49 and 50: Infiltration Rain Garden Stormwater
Page 51 and 52: Infiltration Rain Garden Stormwater
Page 53 and 54: 12345678910TREE, SHRUB ANDGROUNDCOV
Page 55 and 56: 1123456789101112TREE, SHRUB ANDGROU
Page 57 and 58: 1RAIN WATER LEADER OROTHER INLET4DA
Page 59 and 60: Pervious Paving Stormwater Source C
Page 65 and 66: 1PERMEABLE PAVERS (MIN. 80mm THICKN
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Pervious Paving Stormwater Source C
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Green Roof Stormwater Source Contro
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1WALL CAP FLASHING9WATERPROOF MEMBR
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Infiltration Trench and Soakaway Ma
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Infiltration Trench and Soakaway Ma
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1 GRASS OR OTHER PLANTING2FINISH GR
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Design, Construction and Maintenanc
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Candidate Plant List Stormwater Sou
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Glossary Stormwater Source Control
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Glossary Stormwater Source Control
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Stormwater Source Control Design Gu
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Key ContactsLast revised 11 April 2
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Key ContactsLast revised 11 April 2
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Key ReferencesKey AuthorBarry, K.,
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Key ReferencesKey AuthorDeutsche Ve
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Key ReferencesKey AuthorHorner, R.R
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Key ReferencesKey AuthorLower Hunte
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Key ReferencesLast revised 11 April
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Key ReferencesLast revised 11 April
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Key ReferencesKey AuthorUnited Stat
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