Stormwater runoff quality control in green highway projects

Abstract

Stormwater runoff quality (SWRQ) within a city is influenced by the dual effect of the hydromodification and the pollutant loadings. Highway and road corridors increase impervious surfaces and generate several pollutants which contributory affect SWRQ. The aim of this study is to investigate sustainable highway features in order to protect SWRQ. Specifically, the study identifies green/sustainable highway requirements in terms of criteria and sub-criteria which are weighted and Best Management Practices (BMPs) capable of achieving better control of SWRQ. Discussion with experts in highway development, water resources management, and sustainable development have allowed the study to formulate the theoretical framework of the research and a questionnaire was administrated to professionals in those disciplines to provide their level of agreement using five-level Likert scale rating system. The average index and the factors analysis methods are used to assess and weight the importance of criteria and sub-criteria using the Statistical Package of Social Sciences (SPSS) tool. The study identifies three main criteria, Instrumentation and Monitoring Runoff Quality, Storm Runoff Treatment, and Pollution Reduction Practices for SWRQ control. Those criteria scored an average of 30% of water and environment protection. The most significant sub-criteria are Instrumentation to monitor and analyze pollutants, Ensure entire waste water treatment, and use structural BMPs to treat 90 percentile of annual rain fall. Furthermore, the study reveals that a combination of non structural and structural BMPs has to be adopted to exert better control over SWRQ. Most significant BMPs are Vegetation and Landscaping using native ground cover, Runoff Quality/Peak Rate BMPs, and Minimization of land disturbance by fitting the project into the site.