State of the Practice: Assessing Water Quality Benefits from Street Sweeping

AbstractMunicipal separate storm sewer system (MS4) permittees face costly obligations to reduce pollutant of concern (POC) loadings for achieving waste load allocations (WLAs) assigned from total maximum daily loads (TMDLs). Because of the magnitude of reductions necessary to achieve WLAs at a watershed scale, implementation of nonstructural best management practices (BMPs) that can be applied to large areas within the watershed appears necessary. Street sweeping serves as an example because streets exist throughout urban watersheds, often are directly connected to the storm sewer, and are found to contain an abundance of contaminants. Although pollutant removal from street sweeping has been evaluated for decades, an understanding of the impact on water quality in receiving streams is elusive. The current review of rigorous street sweeping studies, in the context of application toward WLAs, suggests that impacts are potentially significant in reducing downstream pollutant loads. Because there are few adequate sampling studies, a lack of feasible methodologies, and perhaps an inability to evaluate impacts downstream from street sweeping altogether, alternative methods have emerged to quantify POC reductions as measures of effectiveness required for regulatory compliance.