Efficacy of Undisturbed Vegetated Buffers in Capturing Suspended Sediment

Abstract

The U.S. Environmental Protection Agency’s Construction General Permit requires a 50 ft (15 m) undisturbed vegetated buffer to be maintained when construction activities are adjacent to a water body. However, maintaining a buffer is not always feasible, especially in highway construction activities; therefore, a contractor may use alternatives that capture sediment at an efficiency equivalent to an undisturbed buffer. However, little research has been conducted on the sediment removal efficacy of an undisturbed vegetated buffer. Several factors influence the sediment capture efficiency of a natural vegetated buffer, including climate, soils, topography, and vegetation characteristics. This research aimed to explore the sediment removal capabilities of various vegetated buffers with factors common to Nebraska roadway construction projects using the Revised Universal Soil Loss Equation 2 Model. A multiple linear regression model was developed to analyze relationships between 7,776 model iterations. Statistical analysis indicated that decreasing the slope of the buffer and the clay and silt content in the soil increased the sediment removal efficiency of the buffer; this finding matched the conclusions of past research on vegetated filter strips and vegetated buffers. Sediment removal ranged between 77% and 99%, with an average efficiency of 94%—comparable to the efficacy of manufactured sediment barrier practices commonly used on construction sites.