Cooperator: Wisconsin Department of Transportation and Wisconsin Department of Natural Resources
Location: City of Madison
Project Chief: Judy Horwatich
Project Number: BQY26
Period of Project: October 2004–September 2006
updated 2/20/07
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 (January 2006 to June 2006)
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 (July 2006 to December 2006)
Data collected through July of 2006 will be processed and a report completed.
Reports
An investigative report will be prepared in FY07
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