Soil Amendments


Including the use of both soil conditioners and fertilizers, soil amendments make the soil more suitable for the growth of plants and increase water retention capabilities. The use of soil amendments is conditional on their compatibility with existing vegetation.

Design Variations

A variety of techniques are included as potential soil amendments including aerating, fertilizing, and adding compost, other organic matter, or lime to the soil.

Stormwater Management Objectives


Soil amendments increase a soil's infiltration capacity and thereby add storage volume to a site. Allowing more stormwater to infiltrate on-site decreases the total volume of runoff; good control of small storm events is achieved with the possibility of eliminating runoff. A reduction in total runoff of large storm events is also obtained.

Peak Discharge

By effectively controlling volume and extending runoff duration, soil amendments also diminish the peak discharge from the site. The maximum stormwater flow rate is reduced by the enhanced infiltration capability of the site and the additional storage volume that is realized in the amended soils.

Water Quality

Amended soils have the ability to remove pollutants through sorption, precipitation, filtering, and bacterial and chemical degradation. Water quality improvements in compost-amended soils are realized because surface runoff volumes are significantly lower from compost-amended soils than conventional soils, and compost materials are less prone to erosion than topsoil or compacted subsoil. As a result, while pollutant concentrations in many compost materials are far higher than in topsoil or compacted subsoil, the mass discharge of most soluble and adsorbed pollutants in surface runoff is far lower in amended soils than in conventional soils.

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