Engineering Characteristics of Compost Used for Erosion and Sedimentation Control

The importance of minimizing detrimental impacts of erosion on construction sites has been considered a pressing issue for decades. Conventional erosion control near wetlands utilizes hay bales and silt fences. Although these conventional methods may reduce the amount of erosion, their effectiveness is infrequently reliable. Recently, compost berms and compost filled geo-fabric tubes have been used as a means of erosion and sedimentation control. Compost used for this purpose comes primarily from agricultural (non-animal) and landscape waste. Up to now, most of the research on compost as an erosion and sedimentation prevention material has been on the observed efficacy of the methodology. The research presented in this paper investigates two engineering aspects of compost. The first aspect is the material properties of the compost using standardized geotechnical test methods. These tests include specific gravity, grain size distribution, hydraulic conductivity, direct shear tests, and triaxial tests. The second aspect is the geoenvironmental influence that the compost has on the water passing through. The laboratory test program consisted of passing synthetic rain water through compost samples and measuring the chemical and pathogenic content in the effluent. The compost used for erosion and sedimentation control is typically wood waste, and landscape/vegetative waste composts. For the material properties tests, three different composts, which are used by landscape contractors, were tested. For the geoenvironmental tests, forty different samples from locations throughout Massachusetts were used. Tests included of nutrient, chemical, biological, suspended solids and pH analyses. Test results indicated negligible impact of effluent on protected wetlands as compared with the traditional use of silt fences and hay bales.