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Line 5: − + + + + + + + + + + − + − An example of sandy loam topsoil is + − *60 % sand, − *25 % silt, − *15 % clay, − *organic matter 5 %, and − *pH value of 6 - 7.5. − Topsoil must be capable of sustaining vigorous plant growth and be free from toxic material and roots, stones or debris over 50 mm in diameter. Specify that samples of topsoil from each source to be drawn upon be provided to the consultant for visual inspection, along with topsoil quality test results from an accredited soil testing laboratory, or a quality assurance certificate from the supplier. We recommend restoring a minimum topsoil depth of 200 mm for planting turf areas, and 400 mm for planting perennials, shrubs and trees.
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The factors to consider in determining a suitable soil mix for a vegetated stormwater practice include the following:
The factors to consider in determining if a topsoil is suitable for use as planting soil for a vegetated stormwater practice, or use in producing a bioretention filter media mixture include the following:
* Must be friable and capable of sustaining vigorous plant growth;
* Must be free from toxic material and roots, stones or debris over 50 mm (2") in diameter;
* Should not have been passed through sieves or screens smaller than 50 mm (2”) to avoid eliminating peds;
* Should have a Loamy Sand, Sandy Loam, Sandy Clay Loam, Loam or Silty Loam soil texture;
* For use as planting soil for a vegetated stormwater practice , the topsoil must contain a minimum of 5% organic matter by dry weight or be amended so, through addition of an organic soil conditioner;
* For use in producing bioretention filter media Blend B (water quality treatment priority), the topsoil must contain at least 9%, and not greater than 36% clay-sized particles and at least 2% organic matter by dry weight.
* Must have a pH of between 6.0 and 8.0;
* Must have a sodium absorption ratio less than 15;
* Must have a cationic exchange capacity greater than 10 milliequivalents per 100 grams (meq/100 g).
Specify that topsoil must be friable, neither heavy clay nor of a very light sandy nature.
Specify that 4 litre samples of topsoil, from each source to be drawn upon, be provided to the consultant for visual inspection, along with topsoil quality test results from an accredited soil testing laboratory, or a quality assurance certificate from the supplier.
We recommend a planting soil or filter media depth of 300 mm to support grasses, 600 mm for shrubs and perennials, and 1000 mm for trees.
[[category: materials]]
[[category: materials]]