MSRC2019: Mass, moisture, nitrogen, and phosphorus in street sweepings collected from five cities in the Twin Cities Metropolitan Area, Minnesota

Abstract

Quality of many urban water bodies is impaired because of phosphorus (P) loading from stormwater runoff. Trees near impervious surfaces contribute significantly to this P loading. Mounting evidence indicates that street sweeping, by removing nutrient-rich litterfall from streets, can effectively reduce inputs of pollutants to stormwater and reduce maintenance of downstream BMPs. Yet, street sweeping remains an underdeveloped BMP for P source reduction, as currently there is no easily implementable method for crediting sweeping practices that is approved by the Minnesota Pollution Control Agency (MPCA). Thus, water quality credits for street sweeping practices are typically not applied to permit conditions such as Total Maximum Daily Loads (TMDL) Waste Load Allocations in Minnesota. Through a UMN-MPCA-city partnership, we collected data on street sweeping loads including: sweeper volume, wet mass of solids, dry mass of solids, and nitrogen and phosphorus concentrations in sweepings and loads removed by different street sweeper types throughout the snow-free season (spring, summer, fall), across the range of tree canopy covers and species composition typical of Minnesota’s cities. Partner cities included Forest Lake, Minneapolis, Prior Lake, Roseville, and Shoreview.