PORT ANGELES — The state Department of Ecology is reviewing the city’s Dec. 21 rainfall-swollen overflow of 1.5 million gallons of untreated sewage and stormwater runoff into Port Angeles Harbor.
The deluge, which overloaded the city’s 4-year-old, $46 million combined sewer overflow (CSO) system and inundated the region, appears to have “overwhelmed the system as it was designed,” Steve Ogle, Ecology’s lead engineer for municipal operations for the southwest office, said Wednesday.
It was Port Angeles’ second combined sewer overflow in 2020; the first two since the costliest public works project in the city’s history was completed in 2016.
In February, 452,000 gallons of sewage and runoff spilled into the harbor, overwhelming the CSO system. During the storm, 17,000 gallons of sewage and stormwater bubbled up from a manhole at N and Fourth streets between Ediz Hook and the Elwha River and gushed into the Strait of Juan de Fuca.
The CSO system was built to keep such overflows to a minimum, city officials said. During an October 2013 rainfall, 8 million gallons of raw sewage and stormwater discharged from the city’s four outfalls — two at the downtown waterfront esplanade and one each at Peabody Creek near its entry point to the harbor and at Francis Street Park.
According to the city’s 59-page waste discharge permit, the outfall locations are at Oak Street and Railroad Avenue. Laurel Street and Railroad Avenue, and at Peabody Creek, with a fourth primary outfall using the Strait as the receiving body of water. To see the permit, go to ecologypermitpa.
City and state officials say the system built in 2016 was intended — to a point — to prevent stormwater and raw sewage from pouring into a harbor already sullied by timber mill-related industrial waste.
“We’re still gathering information, still talking to the city, and from what it seems, they have complied with reporting requirements, and they did that in a timely manner for all four locations,” Ogle said of the Dec. 21 CSO release.
“We’re not necessarily looking at a penalty. We’re just gathering information and trying to understand what happened.
“Lessons learned and other ways to manage that if we have a recurrence, those are probably the key things we’ll be looking at,” Ogle said, adding, “there’s a good chance we will see this again.”
That will likely be due in part to climate change, Ogle said.
“It’s hard to say what will happen in the future, but things definitely seem to be going that way, with climate change predicted that we see, so it’s wise to plan ahead,” he said.
“The increased intensity and duration of those [rain] events is an expected part of the climate changing.”
The city’s CSO system overflow management apparatus was designed using scientific data and rain projections utilized a half-decade ago, Ogle said, calling the Dec. 21 rainfall “an outlier event where actual rainfall exceeds projections, and this could be one of those events.”
Review in progress
Ogle said the agency’s review of the CSO release should be completed by spring and definitely by the summer.
“If enforcement become’s part of the incident,” he said, “they will know something by summertime.”
The combined sewer overflow system that serves Thurston County, Lacy, Olympia and Tumwater — the only other CSO system in the southwest region — also reported overflows, Ecology spokeswoman Colleen Keltz said in an emai.
“Port Angeles was certainly not alone in issues related to the major rain event,” Keltz said.
CSO systems are designed to release overflow only from permitted outfalls that must be controlled so they don’t discharge, on average, more than once a year.
“Whether a city has a combined sewer system or not, overflows from the collection system out of pump stations or manholes are not permitted and Ecology expects the municipality/sewer district to invest in and maintain their sewer system in order to prevent these from occurring,” Keltz added.
Hunter said the raw sewage is to an extent diluted in stormwater that in combined form flows into the harbor during combined sewer overflows.
A key component of the city’s CSO system is a 5-million-gallon tank formerly owned by Rayonier Inc. that stores the raw sewage and stormwater for treatment at the city’s wastewater treatment plant before it ends up in the harbor.
Hunter said the tank mitigated most of the effluent overflow problems caused by major rainstorms before the CSO system was built.
But it still has a set capacity, and when the recent rainfall hit, the groundwater table was already high, like an 8-ounce glass of water with 5 ounces already in it, he said.
“We had a system that already had stormwater in it,” Hunter said.
“Our system was designed and approved by [Ecology] to release the CSO when the system has exceeded capacity and we are at risk of catastrophic failure to the plant.”
Hunter said at the time of the release, both the 5-million-gallon storage tank and wastewater treatment plant were at capacity, as were lift stations, which pump water or sewage to higher elevations, and some sewer mains, “and the water was still coming.”
If the city designed a CSO system to handle all rainfall events, “sewer bills and stormwater bills would get to the point where nobody could afford it,” Hunter said.
“We had to design it to the best of our ability.
“Those overflows are allowed in certain situations,” he added.
“That doesn’t mean they are any less painful.
“The converse of not doing so is millions and millions of dollars worth of damage.”
Hunter said CSO system improvements are being planned that will allow the system to better cope with future high rainfall events.
An estimated $2.2 million Lift Station 3 force main improvement project is slated for design in 2025 and construction in 2026.
The city’s entire wastewater treatment system will be analyzed in a $300,000 wastewater comprehensive plan.
And a hydraulic model will be created “to see how to react to events” and plan for future capital projects, Hunter said.
“It will give us the ability to look at future development in the city and make sure we are planning facilities correctly so we are not hindering future development.”
For more on combined sewer overflows, go to a Department of Ecology website at ecologycso.
Senior Staff Writer Paul Gottlieb can be reached at 360-452-2345, ext. 55650, or at firstname.lastname@example.org.