Enhanced roadside drainage system for environmentally sensitive areas.

Stormwater runoff from roadways that encroach upon environmentally sensitive areas (ESAs) is one of the leading causes of degradation in urbanizing watersheds around the world. This is due to toxicity of the pollutant cocktail commonly found in roadway runoff, including heavy metals and sediments, as well as road salts from winter maintenance operations. This paper presents a novel design of an enhanced roadside drainage system (ERDS); an improved roadside drainage system that is intended to protect groundwater recharge zones and sensitive aquatic species in ESAs. The methods highlighted in this paper can be used to select soil amendments and size filter media for ERDS based on a combination of anticipated roadway pollutants and loads, treatment media efficacy and capacity, and consideration of applicable regulatory guidelines. The design of the ERDS must ensure compliance with the regulatory guidelines related to the protection of groundwater recharge zones as well as the receiving streams to protect priority species living therein. The performance monitoring results from a pilot-scale ERDS are presented to provide guidance for the key novel aspects of the design.