Testing of High-efficiency Street Sweeping on Highways
Project Number: BQY26
Project Chief: Judy Horwatich
Project Topics: NPDES
Cooperators: Wisconsin Department of Transportation; Wisconsin Department of Natural Resources
Period of Project: October 2004–September 2006
The control site will be swept once per week with a broom sweeper. Storm discharge and water-quality samples will be collected for at least 15 storms. Event Mean Concentrations (EMC) will be calculated at one water-quality monitoring site. The test site evaluation will compare changes in the dirt load on the roadway to predict the benefits of three sweeping formats.
Problem
The Wisconsin Department of Transportation (WDOT) is required to improve the quality of runoff from roadways under their control as part of the National Pollution Discharge Elimination System (NPDES) in agreement with the Wisconsin Department of Natural Resources (WDNR). A possible cost-effective method to control stormwater-runoff pollutants on urban freeways is the use of high-efficiency street sweepers.
Objectives
The objectives of this project are to: (1) determine the effectiveness of street sweeping in removing pollutants from highways by alternating the technique and frequency throughout the project; (2) compare the measured removal efficiencies with manufacturers’ estimates; (3) characterize the variability in freeway runoff quality; and (4) characterize pollutant loading in freeway runoff.
Approach
The control site will be swept once per week with a broom sweeper. Storm discharge and water-quality samples will be collected for at least 15 storms. Event Mean Concentrations (EMC) will be calculated at one water-quality monitoring site. The test site evaluation will compare changes in the dirt load on the roadway to predict the benefits of three sweeping formats. The sweeping formats will include: (1) sweeping at different speeds, (2) using tandem sweepers, and (3) sweeping twice per week instead of once. Roadway vacuuming at both the test and control sites will be done to determine particulate matter accumulation rates on the highway and street-sweeping efficiency. Vacuuming will initially need to occur immediately before and after a sweeper makes a pass.
Results from the water-quality sampling will be used to develop plots describing the amount of pollutants removed from the road surface for different rainfall amounts and intensities. A relation will be developed between the efficiency of each format and the amount of pollutants washed off the road surface. This relation will quantify the water- quality benefits of each street-sweeping format.
Progress
Data collection continued for flow, precipitation and water-quality samples. All data are being stored in the USGS NWIS database. Vacuuming of the test and control site continued through June 2006.
Plans
Data collected through July of 2006 will be processed and a report completed.
Publications and Reports
An investigative report will be prepared in FY07
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