Engineered (bioretention) media amendments material properties and specifications

Engineered (bioretention) media amendments material properties and specifications.
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Property	Al- and Fe-water treatment residuals	Ca-water treatment residuals1	Iron	Expanded lime	Expanded aluminum	Taconite
Phosphorus leaching	No	No
Phosphorus retention	Yes	Yes
Handling concerns		Dust may be corrosive and irritant to skin and eyes [1]
Soil hydraulic properties		Mixed results; has shown clogging when incorporated into soil [2]
Soil physical properties		Mixed results; may initially improve soil structure but over time may impair structure through formation of cementitious compounds [3]
Plant effects		Improves plant response in acid soils; may have adverse effects if pH becomes elevated [4]
Availability		Depends on source; many materials are widely available as they have been treated as wastes and landfilled (e.g. spent lime) [5]
Specifications available		No [6]
Cost		Can be inexpensive if sources exist locally (e.g. spent lime from water treatment)
Research needs		Performance in incorporated media; design specifications; maintenance requirements
Applications		[7]
Chemical and physical properties		[8]
Sustainability		Sustainable
Potential contaminants		Elevated pH; avoid waste products that may have elevated concentrations of metals (e.g. spent lime from wastewater treatment)
Test methods		Standard test methods not available; methods may be described in individual reports [9]
Effects of aging		Not expected to be a concern [10]
Notes

¹Includes spent lime