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
Soil physical properties Mixed results; may initially improve soil structure but over time may impair structure through formation of cementitious compounds
Plant effects Improves plant response in acid soils; may have adverse effects if pH becomes elevated [2]
Availability Depends on source; many materials are widely available as they have been treated as wastes and landfilled (e.g. spent lime) [3]
Specifications available No [4]
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 [5]
Chemical and physical properties [6]
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 [7]
Effects of aging Not expected to be a concern [8]
Notes

1Includes spent lime