Street & Parking Lot Sweeping

=Key components of a successful sweeping program

Pollutants collect on surfaces in between storm events as a result of atmospheric deposition, vehicle emissions, winter road maintenance, construction site debris, trash, road wear and tear, and litter from adjacent lawn maintenance (grass clippings). Sweeping of materials such as sand, salt, leaves and debris from city streets, parking lots and sidewalks prevents them from being washed into storm sewers and surface waters. Pollution Prevention and the MS4 Program 15

Timing, frequency and critical area targeting greatly influence the effectiveness of sweeping. This fact sheet provides an overview of studies assessing the benefits of street and parking lot sweeping and guidance on improving the pollution reduction benefits of sweeping programs applicable to MS4 SWPPPs.

Benefits / Pollution Reduction

Regular street sweeping reduces the amount of pollutants that get washed into the storm drain and ultimately discharge to lakes, rivers and wetlands. Targeted pollutants include sediment, trash and debris, leaves, organic matter and nutrients; metals and hydrocarbons. The following pollutant removal efficiencies for total solids (TS), total phosphorus (TP) and total nitrogen (TN) are from a conceptual model developed by the Center for Watershed Protection based on research findings from a variety of studies.

This image shows street sweepings can be filtered and recycled for sanding or filling
Street sweepings can be filtered and recycled for sanding or filling Image Courtesy of Emmons & Olivier Resources, Inc.

The lower removal efficiencies represent monthly street sweeping by a mechanical street sweeper. The upper efficiencies characterize the pollutant removal efficiencies using a regenerative air or vacuum street sweeper at weekly frequencies. Note that the relatively high frequencies of sweeping generate particularly low removal efficiencies, indicating that sweeping, although an effective aesthetic practice, does not necessarily translate into improved water quality. This is a similar finding of Selbig and Bannerman (2007) in their study of street sweeping in Madison, WI. Even so, every pound of trash and debris removed by sweeping is another pound not entering local waterbodies.

Pollutant removal efficiencies from street sweeping for total solids, total phosphorus, and total nitrogen. Source: Deriving Reliable Pollutant Removal Rates for Municipal Street Sweeping and Storm Drain Cleanout Programs in the Chesapeake Bay Basin. Center for Watershed Protection.
Link to this table

Frequency Technology TS % TP % TN %
Monthly Mechanical 9 3 3
Regenerative Air/Vacuum 22 4 4
Weekly Mechanical 13 5 6
Regenerative Air/Vacuum 31 8 7

Program Development & Implementation

Surface Sweeping Program Assessment

The Center for Watershed Protection recommends considering the following questions in order to improve the efficiency and effectiveness of your surface sweeping program. Image Courtesy of Emmons & Olivier Resources, Inc.

  • What surfaces or streets in the community are dirtier than others (e.g. have higher street particulate matter loadings compared to others)? Which streets drain to sensitive water bodies? Prioritize streets with higher loadings. The City of Rochester, New York, has an online street sweeping request form. This contributes to the City’s ability to identify dirty streets and surfaces for more frequent cleaning.
Many cities identify street areas draining to sensitive receiving waters, such as lakes, or to BMPs that could clog with debris and prioritize sweeping on those streets. Consider conducting a street and storm drains investigation, a visual inspection of pollutant accumulation along streets, curbs and gutters, in lake deltas, and storm drain inlets based on the Center for Watershed Protection’s Urban Subwatershed

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