To Sweep or Not to Sweep? San Diego’s Street Sweeping Pilot Study

By Clem Brown & Jennifer Nichols Kearns

The Storm Water Department implemented a Street Sweeping Pilot Study starting in April 2008 to determine if enhanced sweeping is a cost-effective solution for reducing pollution and meeting existing and future total maximum daily load compliance targets. The two goals of the project are:

1. To determine whether different sweeping frequencies help reduce pollution, specifically debris and fine metal particles, in both residential and commercial areas; and

2. To find out if newly acquired vacuum-assisted sweepers are more efficient or cost-effective than conventional sweepers.

Three pilot communities were chosen for this study: Mid-City, which impacts Chollas Creek and San Diego Bay; Clairemont, which drains to Tecolote Creek and Mission Bay; and La Jolla Shores, which drains to two areas of special biological significance. Locations for this study were selected based on a high potential for metal contaminants.

The first phase included dry-weather debris analysis to determine the most effective and efficient sweeper technology and sweeping frequency. The second phase included a wet-weather analysis to determine if enhanced sweeping produced any beneficial impacts to water quality.

Since the study began, the department has swept the equivalent of more than 9,500 miles of streets and collected more than 381 tons of trash and debris. A significant amount of heavy metals has been removed from city streets as well.

Although the City continues to analyze data in order to make recommendations, preliminary results indicate that street sweeping has a positive impact on water quality by providing an effective means of reducing pollutant concentrations in storm water runoff.

Comparisons indicate that a vacuum sweeper is more effective in reducing pollution than a mechanical sweeper under certain conditions (e.g., topography). The data also indicates that conducting aggressive sweeping using a vacuum sweeper is more efficient than sweeping at the same frequency with a mechanical sweeper.

The Storm Water Department is committed to protecting water quality and preserving natural resources in San Diego. With studies like the Street Sweeping Pilot Project, the Department will continue to identify new opportunities to reduce pollution and urban runoff in order to protect our region’s water quality.

Clem Brown is senior planner for the City of San Diego Storm Water Department. Brown can be reached at cmbrown@sandiego. gov. Jennifer Nichols Kearns is senior public information officer for the City of San Diego Storm Water Department. Nichols Kearns can be reached at jennifernk@sandiego.gov.

Source: Storm Water Solutions July-August 2010 Volume: 4 Number: 6 Copyright ^© 2010 Scranton Gillette Communications