Holistic evaluation of inlet protection devices for sediment control on construction sites.

ABSTRACT

To address the deleterious impacts of excess soil erosion from the construction sites, the United States Clean Water Act requires that erosion and sediment control measures (ESCs) be implemented on construction projects disturbing more than 0.4 ha. Inlet protection devices (IPDs) are a common ESC utilized on construction projects to reduce the amount of sediment entering storm sewers. In Ohio, regulatory agencies use approved, non-proprietary IPDs made from commonly available materials (e.g., silt fence, geotextile, lumber, and aggregate) to mitigate sediment on construction projects; however, these IPDs often rely on extended ponding to remove sediment and require frequent maintenance making these unsuitable for road construction projects. Commercially manufactured (i.e., proprietary) IPDs which rely on filtration to quickly dewater following rainfall may prove more practical for road construction projects. However, little research which quantitatively compares the holistic performance of these two types of IPDs in field settings has been performed to date. To address this knowledge gap, the performance of 24 proprietary IPDs was evaluated at field-scale using simulated construction site runoff and compared to three non-proprietary IPDs currently approved for use in Ohio. Bypass flows, which typically occurred due to poor IPD fit to standard drainage inlets used in Ohio transportation settings, significantly increased effluent total suspended solids (TSS) and turbidity compared to tests of IPDs where bypass did not occur. Overflow, or intentional bypass around primary IPD flow pathways during high flows, did not significantly impact effluent water quality. Despite differences in treatment mechanisms (i.e., sedimentation versus filtration), the water quality performance of non-proprietary and proprietary IPDs were not statistically different, indicating comparable sediment removal was provided by both categories. Findings from this research can provide design engineers and state regulatory agencies the necessary tools to evaluate IPD performance in road construction settings and, ultimately, alleviate the impact of excess sediment discharged from construction sites.