Difference between revisions of "Topsoil"

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The factors to consider in determining a suitable soil mix for a vegetated stormwater practice include the following:
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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:
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* Must be friable and capable of sustaining vigorous plant growth;
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* Must be free from toxic material and roots, stones or debris over 50 mm (2") in diameter;
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* Should not have been passed through sieves or screens smaller than 50 mm (2”) to avoid eliminating peds;
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* Should have a Loamy Sand, Sandy Loam, Sandy Clay Loam, Loam or Silty Loam soil texture;
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* 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;
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* 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.
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* Must have a pH of between 6.0 and 8.0;
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* Must have a sodium absorption ratio less than 15;
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* Must have a cationic exchange capacity greater than 10 milliequivalents per 100 grams (meq/100 g).
  
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Specify that topsoil must be friable, neither heavy clay nor of a very light sandy nature.  
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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.  
  
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An example of sandy loam topsoil is
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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.
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*60 % sand,  
 
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*25 % silt,
 
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*10 % clay,
 
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*organic matter 5 %, and
 
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*pH value of 6 - 7.5.  
 
  
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Topsoil must be capable of sustaining vigorous plant growth and to be free from subsoil, roots, vegetation, debris, toxic materials and stone over 50 mm diameter. Specify that topsoil sample must be provided to the consultant for testing and analysis including herbicide or atrazine content. All topsoil supplied must conform to a sample provided. Minimum topsoil depth is 150 mm for turf areas and ranging to 1.25 m for perennials, shrubs and trees.
 
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Avoid creating a "bathtub" effect where isolated areas of coarser soils or loamy sands are surrounded by fine soils or clay. The design engineer and landscape architect should review both subsoil and topsoil materials for compatibility of compactness and texture in planting areas of the LID Practice. Methods, such as soil amendment and preparing a larger planting bed, may be required to prevent discontinuous soil layers. In bioretention practices with a loamy sand soil media placed in clay soil textures, an underdrain is necessary.
 
  
 
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Latest revision as of 16:53, 11 September 2020

  • Topsoil may be material that was stripped from the project site and stored in stockpiles for re-use, or material imported to the site from a supplier provided the physical and chemical characteristics are within acceptable ranges.
  • Topsoil shall be in compliance with Ontario Regulation 153/04 Record of Site Condition standards for soil quality or as amended through Ontario Management of Excess Soil - A Guide for Best Management Practices.
  • Soil laboratory reports shall certify the material to be suitable for re-use on residential, parkland, institutional, industrial, commercial, or community landscapes for the germination of seeds and the support of vegetative growth.

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 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.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

The engineered soil component of bioretention cell or dry swale designs, typically with a high rate of infiltration and designed to retain contaminants through filtration and adsorption to particles.

Mineral particles which are smaller than 2 mm, and which are free of appreciable quantities of clay and silt. Coarse sand usually designates sand grains with particle size between 0.2 and 0.02 mm.

1. A mineral soil separate consisting of particles less than 0.002 millimeter in equivalent diameter. 2. A soil texture class. 3. (Engineering) A fine-grained soil (more than 50 percent passing the No. 200 Sieve) that has a high plasticity index in relation to the liquid limit. (Unified Soil Classification System).

1. A mineral soil separate consisting of particles less than 0.002 millimeter in equivalent diameter. 2. A soil texture class. 3. (Engineering) A fine-grained soil (more than 50 percent passing the No. 200 Sieve) that has a high plasticity index in relation to the liquid limit. (Unified Soil Classification System).

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