Developing a street sweeping credit for stormwater phosphorus source reduction

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 new
UMN-MPCA-city partnership, we aim to use to improve empirical models to enable the MPCA
to develop and disseminate a stormwater P crediting program for street sweeping. In
partnership with three cities (Minneapolis, Roseville, Shoreview), we will develop new empirical
relationships among sweeper volume, wet mass of solids, dry mass of solids, and P 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. We will use these relationships to develop methods to calculate P load reductions from
street sweeping and guidance for applying calculated load reductions as credit toward
achieving water quality goals. Methods will be integrated into existing calculators and the
Minnesota Stormwater Manual, and disseminated in webinars, workshops, presentations,
meetings, and written material.

2019 Midproject Presentation .pdf

Project Staff: 

Lead Investigator: Sarah Hobbie, Department of Ecology, Evolution and Behavior, University
of Minnesota, shobbie@umn.edu
Co-Investigator: Lawrence Baker, Department of Biosystems and Bioengineering, University
of Minnesota,
Co-Investigator: Jacques Finlay, Department of Ecology, Evolution and Behavior, University of
Minnesota, jfinlay@umn.edu
Co-Investigator: Mike Trojan, Minnesota Pollution Control Agency, mike.trojan@state.mn.us
Co-Investigator: David Fairbairn, Minnesota Pollution Control Agency,
david.fairbairn@state.mn.us

Project Duration: 

January 1, 2019 – June 30, 2020