Difference between revisions of "Talk:Green Roofs Design Guide"

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!colspan="2" style="background:white; color:black"| LID Practice
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Revision as of 17:06, 10 October 2017

LID Practice CANADA United States
Green Roof CVC+TRCA (Factsheets-2010)[1] LID-SWM Guide 2010[2] LID-Design Guide Edmonton- 2014 New York State SWM Design Manual-2015 Massachusets 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 Minnesota SW Manual-2016 Tennessee-LID Development-SWM 2016 Texas-LID Technical Guidance Manual-2013 Oregon SWM Manual-2014 Oregon State Univ. Fact Sheets-2011
Slope (%) <= 10 <= 10 < 5 (requires sloped underdrain), 5-20 (gravity drainage), > 20 lath grid is required See Table 2 for Media specs (Below)
Green roof assembly Weight(kg/m2) 80 290-967.7 (Intensive), 129.1-169.4 (Extensive)
Growing medium depth (cm) 4-15 4-15
Intensive > 15 > 15 20-60
Extensive <= 15 <= 15 10-15
Fertilizer applications (nitrogen/m2) < = 5.0 g
Porosity of the drainage Layer (%) > = 25% > = 25%
Ratio of impervious area to treatment facility area, % 1:1 CDA:GR size +25% DA not limit, generally no runoff from surrounding area
Plant density Seeds >= 325/m2, Cuttings>= 12 kg/100m2, Plugs>= 11/m2
Filter Media
Organic 25% < 5% <20% < 15% <20% < 15% See Table 1 for media parameter ranges < 15% < 20% 25% 20%
Light Weight in-organic 75% 95-100 % 80-90% 100% > 85% 80-90% 85-100 % 80-90 % 80-90 % 50%
CEC > 10 > 10 > 10
pH 6.5-8 6.5-7.8 6.5-8
Sand S: 95%; D:85-95%
Silt S: <5%; D: 5-15%
Clay 0%
P-Content E: 2-10; I:2-15
Topsoil 25%
Porous Material 70%
Digested fiber 10%
Table 1: Recommended green roof growing medium parameter ranges
Parameter Extensive green roofs Intensive green roofs
pH 6.5 to 7.8 6.5 to 7.8
Nitrate-N (mg/L) 1 to 4 2 to 32
Ammonium-N (mg/L) 0.1 to 0.8 0.1 to 0.8
Nitrogen (total) (mg/L) 2 to 8 2 to 32
Phosphorus (total) (mg/L) 2 to 10 2 to 15
Potassium (mg/L) 8 to 32 8 to 64
Calcium (mg/L) 100 to 300 100 to 300
Magnesium 10 to 80 10 to 80
Iron (mg/L) 8 to 32 8 to 32
Manganese 1 to 8 1 to 8
Boron (mg/L) 0.04 to 0.6 0.04 to 0.6
Sodium (mg/L) <20 <20
Zinc (mg/L) 1 to 10 1 to 10
Soluble salts (mmhos/cm) 0.4 to 1.2 0.4 to 1.2
Sodium Absorption Ratio (SAR) <2 <2
Table 2:Example green roof media specifications
Parameter Specification
Noncapillary pore space at field capacity 155 (vol.)
Moisture content at field capacity 12% (vol.)
Maximum media water retention 30% (vol)
Alkalinity, CaCo3 equivalents 2.50%
Total organic matter by wet combustion 3-15% (dry wt.)
pH 6.5-8.0
Soluble Salts 6 mmhos/cm
Cation exchange capacity 10 meq/100g
Saturated hydraulic conductivity for single media assemblles 0.05 in/min
Clay fraction (2 micron) 0
Pct. Passing US#200 sieve (i.e., silt fraction) 5%
Pct. Passing US#60 sieve 10%
Pct. Passing US#18 sieve 5%-50%
Pct. Passing 1/8 inch sieve 20%-70%
Pct. Passing 3/8 inch sieve 75%-100%