Over Labor Day, Snohomish County residents received an unwelcome primer on the mechanics of combined sewer overflows. Thursday’s biblical deluge maxed out a combined sewer system conceived before the advent of sewage treatment plants. The result was an output (in English, “dumping”) of domestic sewage and industrial wastewater consistent with the system’s antiquated design.
Langus Park, Rotary Park and Jetty Island were temporarily closed and Howarth Park and Pigeon Creek Park beaches remained closed on Monday. Pathogens can be absorbed by swimming or ingesting the contaminated water.
An Environmental Protection Agency map pinpoints the 772 communities nationwide that, like Everett, use combined sewer systems. In addition to the Pacific Northwest, CSO’s are concentrated in the Northeast and Great Lakes region. They are, according to the EPA website, “remnants of the country’s early infrastructure and so are typically found in older communities.” Combined systems fell out of favor by the 1940s.
The latest closures shouldn’t be confused with the July power outage at an Everett sewer-lift station that caused 40,000 gallons of raw sewage to discharge into Port Gardner. The city responded quickly, determining that the primary and secondary backup power feeds had failed. Power was restored and the problem corrected in less than an hour, but the damage was done (not a major accident, but significant.)
The EPA has a CSO control policy that dates to 1994 and continues to inform municipal and county governments. Two CSO champions worth emulating are King County and the city of Portland.
King County has been a leader in green storm water infrastructure, bureaucratese for old-school techniques to minimize storm water runoff. Many of its efforts align with Snohomish County’s. This is particularly true in the area of bioretention, small-scale projects like swales and rain gardens, which absorb runoff. Other components include permeable pavement (it can be pricey and doesn’t work in high-traffic areas) and ‘green’ roofs with low-growing vegetation (barring a sudden interest in English thatch-roofed cottages, the latter may be a non-starter.)
Portland finished its 20-year CSO program in 2011. It adopted an aggressive strategy of street sumps as well as separate sewers for storm water in select neighborhoods. The city also undertook several “big pipe” projects to channel combined sewage directly to its treatment plant.
Overflows happen, but Everett and Snohomish County still must improve their benchmarks for success. Never is the ideal, with once every few years the absolute maximum.