Case studies for street sweeping

Street sweeping is an effective non-structural water quality best management practice for controlling pollutant loading from municipal road surfaces. Debris from road surface degradation and associated pollutants, leaf litter, and trash can accumulate on road surfaces over time. If not controlled, built-up debris will eventually make its way to storm sewer inlets and into the municipal separate storm sewer system (MS4), degrading water quality in receiving waterbodies.

This page provides case studies for street sweeping.

City of Roseville

Roseville street sweeper in operation

The City of Roseville implemented a City-wide street sweeping program in 1990 which completed three to four sweeps a year. Since 2015, the City has completed four to five city-wide street sweeping operations over the course of a given year, targeting periods of street debris buildup associated with spring thaw (March-April), twice during fall leaf litter (October-November), and targeting areas of the City discharging to sensitive water resources. Street sweeping operations are organized by the City’s Streets Maintenance Department. On average, the City removes of 400 tons of material annually during initial spring sweeping operations and about 600 tons annually with all sweepings. The average cost to the City of spring sweeping operations is $46,000 and 440 hours of labor, with subsequent sweeps being significantly less expensive and requiring fewer labor hours.

A barrier encountered by the City early in development of their street sweeping program was related to material testing (i.e., when should collected street sweeping material be tested, how often, and what to do with contaminated materials). After years of operations, the City found the spring sweepings were almost always contaminated, primarily with diesel range organics. Due to the low cost-benefit of screening collected material and limited storage capacity for screened material, the City now ships and landfills all material collected during spring operations. Sweepings collected outside the spring season have not been considered contaminated.

More information regarding the City of Roseville’s street sweeping operations can be found on their municipal website, or by contacting Ryan Johnson, Environmental Specialist, City of Roseville Engineering Department (Ryan.Johnson@cityofroseville.com).

• Project Location: City of Roseville
• Completion Date: 1990 to Present (Ongoing)
• Organizations Involved: City of Roseville Streets Maintenance Department
• Project Budget Summary: Annual cost / hours for Spring street sweeping operations: $46,000, 440 labor hours
• Quantitative Outcomes: An average of 400 tons of debris is collected during spring sweeping operations each year. Using the MPCA street sweeping calculator and assuming an average moisture content of 27.8%, this equates to 238 pounds of phosphorus removed at a cost of $193/lb-P for the spring sweeping.

City of Lakeville – Using Sweepers in Tandem along with Education and Outreach to Address their Rapidly Growing City

City Size (square miles) 37.8 City Population (2020) 69,490 Number and Type of Sweepers Owned by the City 2 mechanical and 1 vacuum (replaced every 10 years) Does the City Use Contractors for Sweeping? No Curb Miles (either owned or managed by the City) 600 lane miles Miles Swept Annually 1,200 lane miles Frequency of Sweeping Spring and Fall Disposal After materials are gathered, they are stockpiled, tested, and then hauled to the landfill. The fall leaves are composted. The amount of fall compost is more than what the city needs. The city is exploring uses for extra material. Annual Sweeping Costs $246,000 Funding Source General fund and the stormwater utility fee

Effectiveness of stormwater BMPs in treating dissolved phosphorus (DP)

37.8

69,490

2 mechanical and 1 vacuum (replaced every 10 years)

No

600 lane miles

1,200 lane miles

Spring and Fall

After materials are gathered, they are stockpiled, tested, and then hauled to the landfill. The fall leaves are composted. The amount of fall compost is more than what the city needs. The city is exploring uses for extra material.

$246,000

General fund and the stormwater utility fee

Lakeville is a rapidly developing community in the Minneapolis-St Paul Metro Area and is adapting to changing needs related to street sweeping. Lakeville currently sweeps in the spring and the fall, focusing on the older parts of the community with more mature trees and in areas close to streams and lakes. The city also deploys sweepers following large storm events. Lakeville begins spring sweeping activities as soon as the gutters are free of snow and ice. Each of the sweepers are equipped with GPS technology, which the city uses to track areas of high-frequency sweeping. In the fall, the city prioritizes leaf pickup based on the species of the old growth trees and when they drop their leaves. Staff move to other locations as priority areas are completed, visiting all city streets two to three times in the fall months. Staff spend approximately 600 hours sweeping during the fall season. In the spring, all three sweepers are used throughout the city multiple times for a total of 900 staff hours. The mechanical and vacuum sweepers are run in tandem in heavy debris areas, with the mechanical sweeper collecting larger debris and vegetation while the vacuum sweeper removes salt and dirt.