Engineered (bioretention) media amendments material properties and specifications

Engineered (bioretention) media amendments material properties and specifications.
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Property	Biochar	Coir	Water treatment residuals1	Spent lime	Compost	Peat	Iron	Wood chips
Phosphorus leaching	No	No to slight
Phosphorus retention	No to slight	No
Handling concerns	Potential explosive concerns in closed space situations; volatile compounds (depending on pyrolysis temperature)	Dust
Soil hydraulic properties	Significant improvement	Significant improvement
Soil physical properties	Significant improvement	Moderate improvement
Plant effects	Beneficial but varies with feedstock	Beneficial
Availability	Multiple distributors	Widely available
Specifications available	Limited due to variability with feedstocks	Yes
Cost
Research needs	Feedstocks suitable for stormwater applications	Phosphorus fate in stormwater applications
Applications	[1]	[2]
Chemical and physical properties	[3]	[4]
Sustainability	Sustainable, but has current market constraints	Sustainable
Potential contaminants	Minor risk - metals and polycyclic aromatic hydrocarbons (PAHs)	Low risk - possible chloride depending on preparation method
Test methods	Not standardized but International Biochar Initiative widely used [5]	Not standardized but multiple methods available [6]
Effects of aging	Varies with production method [7]	Decomposes slowly unless nutrients are added [8]
Notes	Characteristics vary with feedstock and pyrolysis temperature	Coir must be composted or incorporated with compost, lime, fertilizer, and/or microbes

¹Exclusive of spent lime