| Wood chips were studied for their efficacy in controlling soil erosion on construction sites that have disturbed soils on steep slopes. The purpose of the research was twofold: to determine if wood chips could be used to reduce the off-site movement of soil during construction activities, and to find an environmentally sound alternative to the landfill disposal of wood wastes generated in the urban forest. The research was conducted using field plots that received natural precipitation and laboratory plots that received simulated rainfall. At a local construction site, twelve erodible plots were established on an embankment with a 55 percent slope and an elevation change of nearly 12 m. Each plot had a width of 3 m and a slope length of 10 m. A series of flow dividers was installed at the toe of each plot to measure runoff and sediment. The laboratory plots were one meter wide and had a slope length of three meters. A variable slope stand was fabricated to hold the laboratory plots at 40 percent (2.5:1), 50 percent (2:1), and 67 percent (1.51) slope steepnesses. The simulated rain events had a constant intensity of 64 mm/h. Four treatments were studied: large wood chips, small wood chips, a mixture of wood chips sizes, and no chips. The wood chips were applied at a rate that provided coverage to 80 percent of the soil surface.At the construction site, the small wood chip treatment did not produce an erosion rate that was significantly different from the zero-cover plots the large wood chip and mixture of chip sizes were not significantly different from one another but were significantly different from the zero-cover treatment. Overall, as compared to the zero-cover treatment, the small wood chip treatment reduced erosion by 22 percent, the large wood chips reduced erosion by 78 percent, and the mixture of chips sizes reduced erosion by 86 percent. The results of this project indicate that wood chips should be utilized as a soil cover and need not be discarded as solid waste. |
