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A-1 Bioretention Soil Mix with Compost

A-1 Bioretention Soil Mix #8A is a blend of 80% washed coarse sand and 20% sandy loam topsoil. Added to this blend is 20% by volume of our A-1 Lifelike 3/8” Compost. The final blend equates to approximately 60-70% Coarse Sand, 15-20% Sandy Loam, & 15%-20% A-1 Lifelike 3/8” Compost. The blended material is low in silt and clay which allows the material to perform at the required minimum drainage properties of ˃ 5” per hour KSat Perc Rate @ 85% relative compaction. This satisfies civil engineering requirements while maintaining the agronomical properties of a well-graded sand with silt to satisfy the landscape architect’s desire to support growth of plant material. Clay content is limited to provide a minimum cation exchange capacity for healthy plant material if desired.

The uniform sand sizes of A-1 Bio-Retention Soil Mix #8A results in long-lasting pore space and moisture capacity for a reasonably priced, readily available, consistent source of an appropriate soil medium to comply with State Water Quality requirements.

Organic matter incorporated into the A-1 Bioretention Soil Mix #8A helps support vegetation but will affect the Ksat Perc Rate. It is recommended that organic matter is incorporated into the soil medium’s top six inches after installation to relieve compaction or in the planting hole for trees or shrubs to concentrate the amendment where it will benefit the plants and restrict water movement.

Bioretention Soil w/ Compost Mix Cutsheet



A-1 Bioretention Soil Mix #8A is a soil medium for Bioretention Basins and Swales which helps remove contaminants from stormwater runoff as required by the State of California Regional Water Quality Control Board and other government agencies charged with enforcement of these requirements. The ultimate goal is to help prevent contamination of the downstream beneficial water sources of the State.

*NOTE: All materials should be sampled, submitted, and approved prior to shipment or installation as job plans and specifications vary greatly. It is the customer’s responsibility to assure the soil is approved before installation!


A-1 Bioretention Soil should be installed per construction plans or engineers specifications. Compaction should be avoided and ideally, the soil should be installed at less than optimum moisture.


Sieve Analysis % Passing

  • 3/8"-100
  • #495-100
  • #8 40-60
  • #200 <15
  • USDA Soil Classification Very Gravelly Sand
  • PH Range 6.5-8
  • ECe (Salinity) <3.0
  • KSat (Perc Rate) <5.0 inches/hr @ 85% Compaction (Compaction affects permeability)
  • Sand 80-90
  • Topsoil 20% added topsoil (sand component in topsoil shows up in final mix evaluation)
  • Compost 20% added by volume to A-1 Bioretention Soil Mix #8
  • Silt and Clay5% - 15% (from added topsoil and compost)

Specification data subject to change. Additional data available upon request. 

Limitation of Warranties: Seller makes no warranty of any kind, express or implied, regarding the materials; and all warranties, including any implied warranty of merchantability and any implied warranty of fitness for a particular purpose, are hereby excluded.