Seattle's failed winter-storm strategy — which involved dumping nearly 12,400 tons of sand on iced-over streets last December — is causing new problems for a wastewater-treatment plant, where unprecedented amounts of grit from city storm drains have plugged up pumps and triggered emergency repairs.
Seattle’s failed winter-storm strategy — which involved dumping nearly 12,400 tons of sand on iced-over streets last December — is causing new problems for a wastewater-treatment plant, where unprecedented amounts of grit from city storm drains have plugged up pumps and triggered emergency repairs.
“We’re getting hammered,” said Wade Schrader, a maintenance mechanic at the West Point Wastewater Treatment Plant.
Plant operators called the situation “unprecedented” and attributed it to heavy rains that apparently flushed out pockets of sand and gravel still remaining on city streets four months after it was dropped.
The volume of material became so heavy April 16 that it shut down a pump and forced the early shutdown of a basin that filters grit from wastewater before it’s treated and released into Puget Sound.
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Problems at the plant, while unintended, were not exactly unforeseen.
Plant manager Pam Elardo said her boss sent her a newspaper article about the amount of sand Seattle was using to combat a series of storms that rolled over the area in December.
“I looked at it, and thought, ‘Oh, no,’ ” Elardo said last week, as cleanup of one of the plant’s four grit–removal basins continued. The plant is owned and managed by King County but serves as the primary treatment facility for sewage and stormwater originating in Seattle.
Richard Sheridan, spokesman for Seattle’s transportation department, said in an e-mail that the city has swept up more than 11,300 tons of sand since January. That’s more than 91 percent of the nearly 12,400 tons the city says it dropped in what proved to be a largely futile effort to make city streets passable.
The city refused to use salt to clear the roads, citing concerns about its impact on chinook salmon habitat. That policy has since been changed.
Transportation managers dispatched sweepers to clean up the sanding material after the storms passed. They stepped up their efforts in late January — paying a private contractor $42,000 to help them — after receiving reports that bicyclists were being injured by riding into roadside sand berms.
In an e-mail to The Seattle Times in February, Sheridan wrote that “SDOT is confident we are aggressively cleaning the streets and preventing significant amounts of sand from entering catch basins and drainage pipes.”
He did not respond to repeated phone and e-mail requests Friday to discuss how so much sand could end up at the plant if the city’s sweeping strategy had been successful.
A spokesman for Mayor Greg Nickels also did not respond to requests to discuss the issue.
A Seattle Times analysis of transportation-department records shows that managers directing the city’s snow response did not keep a centralized record of where sand was applied to help focus their cleanup. Instead, they relied on the general snow-clearing routes to dispatch sweepers, Sheridan said.
Seattle Public Utilities also has vacuumed sand from drains throughout the city since the storms. But the utility said it was unable to discern how much of the material it collected was dropped during the city’s snow-control efforts.
Annie Kolb-Nelson, spokeswoman for King County’s wastewater division, said most of the sand was generated by the city’s snow-control efforts. But plant operators could not attribute an exact figure to the city. Kolb-Nelson the county removed 2,432 tons of sand and gravel from the plant in 007, and 2,820 tons of grit last year. Amounts of grit removed from the plant in 2009, which would reflect the stormwater runoff, are not yet available.The plant, located next to Discovery Park in Magnolia, removes sand, gravel and other inorganic particles from wastewater before it’s treated. What remains is turned into fertilizer.
Seattle accounts for the bulk of the influent. But the plant also serves parts of north King County and south Snohomish County.
Master maintenance mechanic Todd Smith said that in a decade of work at West Point, he’s never seen so much grit.
No wastewater spills into Puget Sound have been attributed to the sand, but plant manager Elardo said pumps and pipes are taking a beating as the grit scours its way through the system.
Elardo ordered one of the plant’s four grit-removal basins cleaned April 16 after determining that large amounts of sand had clogged a pump attached to the basin.
Cleaning the basins is a smelly operation that is typically done later in the year. The county paid $1,200 in overtime to employees who worked for three days to clean the basin.
Elardo said she expects the other basins to be equally laden with sand, but so far, their pumps have held out.
Logan Harris, public-affairs manager for the King County department that runs the plant, said the wastewater division is “committed to working with Seattle to identify best practices going into the next storm season.”
Susan Kelleher: 206-464-2508 or firstname.lastname@example.org