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Seattle street cleaning dramatically expanded to fight water pollution


Street-sweeping debris removed from streets as part of Seattle’s 15-year plan to protect Seattle’s Waterways.

One of the key elements to the 15-year Plan to Protect Seattle’s Waterways is a nation-leading street-cleaning program. Beginning next year, the city will double the lane miles of arterials being cleaned—from 10,000 to 20,000—to remove pollutants before they wash into public waterways.

The program’s goal is to remove at least 140 tons of pollutants per year — the equivalent of about 410 dump truck loads — from city streets. Although streets compose only 16 percent of Seattle’s surface area, they contribute more than 40 percent of the pollution load in stormwater runoff. Street cleaning, much of which takes place at night, is conducted all over the city.

Since 2011, Seattle has been ramping up a full-scale street-cleaning program and systematically measuring its effectiveness. It is believed to be the first time any U.S. city has undertaken such a study.

“Street cleaning is a cost-effective way to keep neighborhoods clean and enjoyable for children and families across the city,” Mayor Ed Murray said. “Doubling street cleaning will remove tons of street dirt and its attached PCBs and heavy metals from our streets before they run into our storm sewers. It’s an investment in the health of Seattle residents and the environmental quality of our lakes and Puget Sound.”

“For the past four years, Seattle Public Utilities (SPU) and the Seattle Department of Transportation (SDOT) have methodically gathered information on the cost-effectiveness of a citywide street-cleaning program, and the results are very encouraging,” program manager Shelly Basketfield said.

The finely tuned cleaning operation has already prevented a substantial amount of metals and toxins from potentially entering our water bodies. In 2014, the program removed 40 pounds of copper, 80 pounds of zinc, 170 pounds of phosphorus, and 130 tons of fine particulate matter with other attached pollutants.

Over the past four years, street cleaning has intercepted one and a half times the pollutants removed by all other SPU-maintained water quality treatment facilities combined — yet it costs four to ten times less than typical treatment technologies.

The program also uses an advanced system that tracks minute-by-minute cleaning activities to help adaptively manage routes and schedules, and to track street dirt pickup rates.

The overall Plan to Protect Seattle’s Waterways will fulfill a 2013 agreement in which the city promised to reduce sewer overflows to comply with state and federal law. The plan, approved by Council last month, would also keep millions of gallons of storm runoff out of public waterways, reducing threats to human and aquatic health and the region’s quality of life.