Talk:Bioretention Design Guide

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LID Practice CANADA United States
Bioretention CVC+TRCA (Factsheets-2010)[1] CVC-Construction Guide-2012 [2] CVC-Retrofit Guide-2014[3] Toronto- 2016 LID
SWM
Guide
2010[4]
LID-Design Guide Edmonton- 2014[5] New York State SWM Design Manual-2015 Massachu-sets
SW BMP
2013
District of Columbia-SWM Guidebook-2010 San Diego LID Handbook-2014 Alabama LID Handbook-2013 W. Virginia-SWM design guidance manual-2012 Rhode Island-SW design & Installation Standards Manual-2012 Pennsylva-nia
Green St.
design manual
2014
Minnesota SW Manual-2017 Tennes-see
LID SWM
2016
Texas-LID Technical Guidance Manual-2013 Oregon SWM Manual-2014 Oregon State Univ. Fact Sheets-2011
Filter media depth (m)
Depth 1-1.25 1-1.25 1-1.25 0.5-1.0 >= 2.5 ft.
Composition
Topsoil 30-50% 20-30 % 8-20 % Table 1 & 2 (below)
sand 85-88 % Fine sand=0-17%, Coarse to medium sand=71-92 % 85-88 % 85-88 % 85-88 % 50-85 % 50-70 40% 85-88 % 65% sand, 20% sand loam 85-88 % 70-88 % 85-88 % 50-80 % 70-85 % (sandy loam) 85-88 % 66% 60% (sandy loam)
Fines(silt and clay) 8-12 % 8-12 % 8-12 % 7-12 % 8-12 % 10-15% (silt),3-10% (clay), both combined, max 20% clay < 5% 8-12 % 8-12 % 0-12 % silt, 0-2 % clay Silt 40% , Clay 10% 10-20% (silt), max. 10% (clay) 8-12 %
gravel 15%
Organic matter 3-5 % 3-5 % 3-5 % 3-5 % 3-5 % 5-10% 5% 30-40 % 1-5 % 2-5 % 3-15 % 3-5 % 3-5 % 2-10 % 5-10 % 2-5 % 33% 40%
P-index value 10-30 ppm 12-30 ppm 10-30 ppm 10-30 < 15
Soluble salts < 2.0 mmhos/cm
Cationic exchange capacity
(meq/100g)
> 10 10 > 10 > 10 > 10 > 5 > 10 > 5 > 10 > 10 > 5
pH 5.5-7.5 5.5-7.5 5.5-7.5 5.5-7.5 5.5-7.5 5.5-7.5 6-8 6-7 6-8.5 (WQ blend) 6-8 5.5-7.5
Phosphorus 10-30 ppm Table 1 & 2 (below)
Infiltration rate > 25 mm/hr > 25 mm/hr > 25 mm/hr > 25 mm/hr
Surface resistance <= 110 PSI
Sub-surface resistance <= 260 PSI
Saturated hydraulic conductivity , mm/hr 25 min.
P-Content 10-30 < 15 ppm 7-23 mg/kg
Compost (optional) 15-25% 15%
Gravel storage
Void space ratio 0.4 0.4
Depth min. 300 mm min. 300 mm min. 300 mm
Diameter(clear stone) 50 mm 50 mm 50 mm
Pea Gravel Choking Layer depth (mm) 100 100 100
diameter (mm) 3-10 3-10
Mulch
Depth 75 mm <=75 mm 75 mm 75 mm 70-80
Overflow
Overflow invert above the filter bed surface 150-250 <= 250 mm
Monitoring well
Vertical perforated pipe diameter 100-150 mm 100-150 mm 100-150 mm 100-150 mm
Underdrain
Required when infiltration rate
(mm/hr)
< 15 < 15 < 13
Diameter
(mm)
min. 100
(200 recd.)
min. 100
(200 recd.)
min. 200 min. 100
(200 mm recd.)
200 mm 4 inches
Depth above the gravel storage layer 100 mm 100 mm
Available head beween the inflow point and the downstream stream drain invert 1-1.5 m 1-1.5 m Typical CDA 0.1-2.5 acres of 100% IP(<0.5 no underdrain), alternative to checking layer is needle punched non-woven geotextile
Contributing drainage area
Typical 100 m2 to 0.5 hectare 100 m2 to 0.5 hectare 0.5-2 acres preferred, max 5 acres, BR min. size 200 ft2 5 acres
Maximum recommended 0.8 hectare 0.8 hectare
Setback from building Foundation(m) 4 4 4 3 (clay), 5 (heavy clay) see table 3 below
(Impervious drainage/treatment facility) area 5:1 to 15:1 5:1 to 15:1 5:1 to 15:1 < 5:1 loading ratio (DA to IA, DA 100% IP) SA of BR
3-6% of
CDA
sized at 5-8 % of IPCDA BR SA 3-6% of CDA CDA < 5 acres CDA < 2.5 acres CDA < 5 acres BR SA: 6-15 % of IP area
Contributing Slope (%) 1-5 1-5 >1 % and < 33%
Slope of the surface, % <= 1%
Water table depth min. 1.0 m min. 1.0 m > 1.8 3 ft.
Outlet min. 100 mm above the bottom of the facility Difference in elevation between inflow and outflow =4-6 ft (when underdrain is used)
Maximum ponding depth above the filter bed surface 150-250 mm 250 mm 150-250 mm 350 mm 18 inch
Facilties receiving road runoff are not located within time of travel 2 2
wellhead protection areas, year
Drainage time of ponded water after the end of storm event , hr 24 (48 recommd.) < 48 (2 yr. design) Max. 48 hr.
Inlet design for non-point source-grass filter buffer, m 0.5-3.0
Contributing impervious area < 4.0 ha. ` < 15000 ft2
Facility flow velocity < 0.3 m/s-planted area <= 1 ft/sec, tree-shurb-mulch cell
< 0.9 m/s- mulched zone <= 3 ft/sec , grassed cell
Discharge velocity (outlet point) < 4 ft/sec
Side slope (H:V) 4:1 preferred(max 2:1) 3:1 (H:V)
Surface geometery (length/width) 2:1
Infiltration trench (optional)
Depth, m 0.5-1.0
Width, m 1.0-6.0
Bottom slope, % 0
C/N Ratio 12:1-25:1
Table 1: Bioretention media composition
Sand Soil Fines Organic P-Index, milligram/kg Gravel
Water Quality Blend 60-70 % < 5% clay 15-25 % 10-30
Enhanced filtration blend 70-85 % 15-30 % 10-30
North Carolina WQB 85-88 % 8-12 % 3-5 % 10-30
Mix D by dry Weight 60-75 % 25-40 % 2-5 % < 12 %
Mix E 60-80 % 20-40 % MnDot 3890 grade 2 compost 30%
Mix F by weight 75% loamy sand 25 % MnDot grade 2 compost
Table 2: Minimum bioretention soil media depths recommended to target specific stormwater pollutants
Pollutant Depth of Treatment with upturned elbow or elevated underdrain Depth of Treatment without underdrain or with underdrain at bottom Minimum depth
Total suspended solids (TSS) Top 2 to 3 inches of bioretention soil media Top 2 to 3 inches of bioretention soil media Not applicable for TSS because minimum depth needed for plant survival and growth is greater than minimum depth needed for TSS reduction
Metals Top 8 inches of bioretention soil media Top 8 inches of bioretention soil media Not applicable for metals because minimum depth needed for plant survival and growth is greater than minimum depth needed for metals reduction
Hydrocarbons 3 to 4 inch Mulch layer, top 1 inch of bioretention soil media 3 to 4 inches Mulch layer, top 1 inch of bioretention soil media Not applicable for hydrocarbons because minimum depth needed for plant survival and growth is greater than minimum depth needed for hydrocarbons reduction
Nitrogen From top to bottom of bioretention soil media; Internal Water Storage Zone (IWS) improves exfiltration, thereby reducing pollutant load to the receiving stream, and also improves nitrogen removal because the longer retention time allows denitrification to occur underanoxic conditions. From top to bottom of bioretention soil media Retention time is important, so deeper media is preferred (3 foot minimum)
Particulate phosphorus Top 2 to 3 inches of bioretention soil media. Top 2 to 3 inches of bioretention soil media. Not applicable for particulate phosphorus because minimum depth needed for plant survival and growth is greater than minimum depth needed for particulate phosphorus reduction
Dissolved phosphorus From top of media to top of submerged zone. Saturated conditions cause P to not be effectively stored in submerged zone. From top to bottom of bioretention soil media Minimum 2 feet, but 3 feet recommended as a conservative value; if IWS is included, keep top of submerged zone at least 1.5 to 2 feet from surface of media
Pathogens From top of soil to top of submerged zone. From top to bottom of bioretention soil media Minimum 2 feet; if IWS is included, keep top of submerged zone at least 2 feet from surface of media
Temperature From top to bottom of bioretention soil media; Internal Water Storage Zone (IWS) improves exfiltration, thereby reducing volume of warm runoff discharged to the receiving stream, and also improves thermal pollution abatement because the longer retention time allows runoff to cool more before discharge. From top to bottom of bioretention soil media Minimum 3 feet, with 4 feet preferred
Table 3: Recommended minimum setback requirements
Setback from Minimum Distance (m)
Property Line 10
Building Foundation* 10
Private Well 50
Septic System Tank/Leach Field 35
* Minimum with slopes directed away from the building