Low Impact Development for Controlling Highway Stormwater Runoff—Performance Evaluation and Linkage to Cost Analysis

摘要

Highways are major source of stormwater runoff due to their large foot print of paved areas. The runoff can lead to many environmental problems such as non-point source pollution, soil erosion, and flooding. The low impact development (LID) practice, through incorporating best management practice (BMP) elements in linear infrastructure projects such as highways, can provide a cost-effective and environmentally sound solution for on-site control and management of stormwater runoff. Because of the diversity and variety of site conditions across the country, an extensive number of factors have to be considered. For a given project, factors can include soil characteristics such as soil type and infiltration rate; site conditions such as surface vegetation cover, drainage area and pathway, slopes, imperviousness; meteorological conditions such as rainfall; available land space for BMPs, and costs associated with the installation and maintenance of BMPs. To develop a most cost-effective engineering solution for a given site, a large number of scenarios need to be analyzed to evaluate the impact of essential factors aforementioned on the performance of BMPs, which is to be linked to the cost analysis of a given scenario. For practical application, an approach that can be readily deployed for efficient evaluation of many scenarios in relatively short time is needed. Such an approach should be integrated with considerations for cost analysis. Information and reporting in the currently available LID design manuals and related technical documents about such an integrated approach linking extensive performance evaluation with cost analysis is limited. This paper discussed results from our study that takes a modeling approach to evaluate the impact of many aforementioned factors on performance of several BMPs for control of stormwater from highways, as well as the linkage with cost analysis. This study used an idealized catchment and Personal Computer Stormwater Management Model (PCSWMM) for analysis. The modeled BMPs included bioswale, infiltration trench and vegetated filter strip. The analysis results on newly constructed BMPs indicated an average runoff reduction of up to 100% from the infiltration trench, of 70-83% and 68-78% for bioswale and vegetated filter strip, respectively. The linkage between the performance and the costs of BMP installation and maintenance for linear projects were discussed. Findings from this study provides valuable information to support decision-making for selecting and placing cost-effective stormwater BMP for controlling stormwater runoff from highways and beyond.