Water Quality Characteristics and Performance of Compost Filter Berms

The Texas Department of Transportation, in conjunction with the Texas Commission on Environmental Quality and the Environmental Protection Agency, commissioned a study to examine the water quality impacts of compost leachate constituents and structural integrity of unseeded compost filter berms, seeded compost filter berms, and compost/mulch filter socks. Wood mulch filter berms, straw bales, and silt fence were tested comparatively. Three compost types were tested: dairy manure, biosolids, and yard waste. The berms and filter sock material used a mixture of 50 percent compost and 50 percent wood chips. Studies were conducted with low velocity flows. Each of the alternatives was tested for two rounds consisting of three repetitions each round on both sand and clay soils. Results showed that the yard waste compost outperformed the dairy manure compost and biosolid compost in water quality characteristics and structural durability in performance. The berms that were seeded and left in place long term surpassed the unseeded berms in their ability to sustain overtopping and retain their structure.