King County’s largest wastewater treatment facility has been operating on the edge of disaster for years and it’s ill-equipped to deal with the growing population in the region.
That’s one of the conclusions from the independent review of February’s catastrophic failure at the West Point sewage treatment plant in Seattle’s Discovery Park.
Small Footprint, Big Demands
The beach at Discovery Park was chosen as a sewer outfall location in 1904. An upgrade to the facility in 1995 added secondary treatment and other improvements but used up most of the available space on the waterfront parcel.
The report notes that the result – a small and densely packed footprint – makes West Point remarkable compared to other sewage plants in the region.
“It’s smaller than the site of Brightwater plant, yet it’s asked to treat ten times the flow,” said Nick Cooper, one of the consultants from AECOM hired by the County to look into why West Point failed in the early morning hours of Feb. 9.
Speaking to a King County Council committee, Cooper described how torrential rains forced the plant to operate at its peak capacity for 10 to 15 hours.
“And that’s pretty rare for a facility this large – so that’s part of the unique feature that you’re dealing with,” Cooper said.
‘Everything Must Work’
AECOM’s Global Wastewater Practice Leader Beverly Stinson also testified. She echoed the description of unique constraints, including West Point’s location and less-than-optimal design. She said it lacks hydraulic outflows that can function without electricity. Instead, she said it’s like a bathtub that requires pumps to keep water flowing.
“So what that means is that everything must work, for the facility to be able to function, especially during these high peak flows. And that puts a great deal of stress on the operational protocols and procedures and equipment and the staff,” Stinson said.
The report says clearer protocols are needed to help staff prioritize in the event of failures. It notes that during the storm event in February, the plant operator was faced with more than 2,100 alarms in less than an hour. And it was not clear which were critical.
The report also notes that retaining staff at West Point has been challenging, causing additional problems running the facility smoothly.
Facility ‘On the Ragged Edge’
“You’re right on the ragged edge all the time – correct. And it’s remarkable that the operators are able to handle these events,” said Cooper.
No one was killed in the disaster, although one staffer was badly injured and narrowly escaped the flooding. Among the report’s recommendations is better training for emergencies.
AECOM also said it expects storms like the February event to become more frequent in the future because of climate change caused by global warming.
The county’s insurance covers most of the $57-million dollars in damages. But that cannot reverse the estimated 235 million gallons of untreated sewage and storm water dumped into Puget Sound, the effects of which remain unknown.