Summary of recommended bioretention filter media mixes from worldwide sources
Summary of recommended bioretention filter media mixes from worldwide sources
Link to this [[Summary of recommended bioretention filter media mixes from worldwide sources
|table]].
| Guideline | Aggregate | Organic | Note |
|---|---|---|---|
| Auckland Regional Council (2003), Waitakere City Council (2004) | Sandy loam, loamy sand, loam, loam/sand mix (35 - 60% v/v sand) | Not specified | Clay content < 25% v/v1 |
| Prince George’s County, Maryland (2007) | 50 - 60% v/v sand | 20 - 30% v/v well aged leaf compost, 20 - 30% v/v topsoil2 | Clay content < 5% v/v |
| The SUDS manual (Woods-Ballard et al. 2007) | 35 - 60% v/v sand, 30 - 50% v/v silt | 0 - 4% v/v organic matter | 10 - 25% v/v clay content |
| Facility for Advanced Water Biofiltration (FAWB, 2009a) | Washed, well graded sand with specified PSD band | 3% w/w organic material | Clay content < 3% w/w, top 100 mm to be ameliorated with organic matter and fertilizer |
| Seattle Public Utilities (2008) | 60 - 65% v/v mineral aggregate, PSD limit (“clean sand” with 2 - 5% passing #200 sieve), U3 ≥ 4 | 35 - 40% v/v fine compost which has > 40% w/w organic matter content | |
| Puget Sound Partnership (2009) | 40% v/v compost, or 8 - 10% w/w organic matter | ||
| North Carolina Cooperative Extension Service (Hunt & Lord 2006) | 85 - 88% v/v washed medium sand4 | 3 - 5% v/v organic matter | 8 - 12% v/v silt and clay |
| City of Austin (2011) | 70 - 80% v/v concrete sand5 | 20 - 30% v/v screened bulk topsoil2 | 70 - 90% sand content, 3 - 10% clay content, silt and clay content < 27% w/w. Warning not to use sandy loam (“red death”).6 |
1 % v/v is percent by volume; % w/w is percent by weight (mass)
2“Topsoil” is a non-technical term for the upper or outmost layer of soil, however there is no technical standard for topsoil.
3U, Coefficient of Uniformity = D60/D10, where D60 is particle diameter at 60% passing and D10 is particle diameter at 10% passing.
4A specific definition for “medium sand” was not identified. ASTM D2487-10 classifies coarse-grained sandsas those with > 50% retained on the (USA) No. 200 sieve (75 m) and > 50% of coarse fraction passing the No. 4 sieve (4.76 mm). Clean sands contain < 5% fines. Fine-grained soils are silts and clays whereby > 50% passes the No. 200 sieve.
5Concrete sand is described by ASTMD2487-10 as coarse sand that is retained by a (USA) No. 10 sieve (2.00mm)
6“Red death” is commercially available fill material in Austin marketed as sandy loam.