Stormwater Source Control Design Guidelines 2005 - Waterbucket

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Stormwater Source Control Design Guidelines 2005Infiltration SwaleInfiltration Swale SystemDescriptionThe Infiltration Swale System combines aspects of grass swalesand infiltration trenches.The surface component of an infiltration swale is a shallowgrassed channel, accepting flows from small areas of adjacentpaved surfaces such as roads and parking. The swale isdesigned to hold the water quality storm behind a weir, andthen allow it to infiltrate slowly through a soil bed to anunderlying drain rock reservoir system.The surface soils and drain rock reservoir are sized to store thedesign storm event, and to allow it to infiltrate slowly intounderlying soils. A perforated drain placed near the top of thedrain rock reservoir provides an underground overflow, whichalso maintains drainage of adjacent road base courses. Thesurface swale and weir structures provide conveyance forlarger storm events to a surface outlet.Other common terms used are Dry Swale with Underdrain(Stephens et al., 2002) or Swale/Trench Element (MUNLV-NRW, 2001).Photo Credit: Lanarc ConsultantsDrop curb at pavement edge to grassinfiltration swale.Application Designed to treat the water quality volume and conveylarger flows (Stephens et al., 2002). Provision of underground overflow allows use of thetechnique in most soils, including clay with infiltration ratesas low as 0.6mm/hr. Suitable for most development situations – residentialareas, municipal office complexes, rooftop runoff, parkingand roadway runoff, parks and greenspace, golf courses(Stephens et al., 2002). With proper weir spacing, practical for profiles up to 10%slope.Limitations Maximum contributing area 2 ha (Stephens et al., 2002). Minimum depth from base of drain rock reservoir to watertable 610 mm (Stephens et al., 2002). Identify pollutant sources, particularly inindustrial/commercial hotspots, that require pre-treatmentor source control upstream of this BMP. (Maryland Dept.Environmental Resources Program, 2000).Greater Vancouver Sewerage & Drainage District33
Infiltration Swale Stormwater Source Control Design Guidelines 2005Design should provide for drain rock reservoir to drain in96 hours to allow aerobic conditions for water qualitytreatment.Design GuidelinesPhoto Credit: Lanarc ConsultantsFlush curb (left) to grass filter tovegetated (shrubs, groundcover)swale.1. The swale infiltration area should be approximately 10-20% of the upstream impervious area that it serves, with itssizing preferably calculated by continuous flow modelling.2. Flow to the swale should be distributed sheet flow,travelling through a grassy filter area at the swale verges(500 mm min., >3000 mm desirable). Provide pretreatmenterosion control to avoid sedimentation in theswale. Provide non-erodable material, sediment cleanoutbasins, and weir flow spreaders at point-source inlets(Maryland Dept. Environmental Resource Programs,2001).3. Provide vegetated erosion control along all sides of weirand at drainage inlets.4. Pavement edge at the swale may be wheel stop, flushcurb, or reverse curb (Figure 2E). Provide a 25mm dropat the edge of paving to the swale soil surface, to allow forpositive drainage and buildup of road sanding/organicmaterials at this edge.5. Swale planting is typically sodded lawn. Low volumeswales can be finished with a combination of grasses,shrub, groundcover and tree planting to provide a 100%vegetated cover within 2 years of planting.6. Swale longitudinal slope should be 1-2%, or dishedbetween weirs.7. Swale bottom width - 600mm minimum, 2400mmmaximum, flat in cross section.8. Swale surface side slopes - 3(horizontal):1(vertical)maximum, 4:1 preferred for maintenance.9. Weirs to have level top to spread flows and avoidchannelization, keyed in 100mm minimum. Integratedmowing strip is desirable in lawn areas.10. Design stormwater conveyance using Manning’s formula,with attention to erosion and channel stability duringmaximum flows.11. Maximum ponded level: 150mm (Maryland Dept.Environmental Resource Programs, 2001).12. Drawdown time for the maximum surface ponded volume– 48 hours maximum ( 24 hours maximum - MarylandDept. Environmental Resource Programs, 2001).34Greater Vancouver Sewerage & Drainage District
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 and 16: DESIGN PRINCIPLES■ Maximize the a
Page 17 and 18: DESIGN PRINCIPLES■ Literature sug
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 37: Absorbent Landscape Stormwater Sour
Page 41 and 42: Infiltration Swale Stormwater Sourc
Page 43 and 44: FLOWGROWING MEDIUMADJACENT GRADE200
Page 45 and 46: FLOWADJACENT GRADE200GROWING MEDIUM
Page 47 and 48: Infiltration Swale Stormwater Sourc
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
Page 69 and 70: Green Roof Stormwater Source Contro
Page 77 and 78: 1WALL CAP FLASHING9WATERPROOF MEMBR
Page 81 and 82: Infiltration Trench and Soakaway Ma
Page 83 and 84: Infiltration Trench and Soakaway Ma
Page 85 and 86: 1 GRASS OR OTHER PLANTING2FINISH GR
Page 87 and 88: Design, Construction and Maintenanc
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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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