When wastewater disappears down most Eastsound drains, where does it go?
After undergoing aerobic treatment, it eventually winds up in the Salish Sea, at an average rate of 100,000 gallons per day.
It gets there through an 8-inch diameter outfall pipe extending 1,100 feet into President’s Channel, off of North Beach. That pipe had multiple holes knocked into it two years ago by the Port of Orcas’ nearby stormwater outfall pipe and concrete hold-downs, which were tossed around by winter storms and wave action, said sewer plant manager Roy Light.
He said the port has since anchored their stormwater pipe down more effectively, but the sewer outfall pipe has been badly corroded and filled with rocks, and attempts at repair have proven fruitless. Because of the damage, the effluent is being released through the holes closer to shore instead of as intended, through diffusers at the end of the pipe.
The project
Eastsound Sewer and Water District is now working on engineering a replacement for the pipe.
Chris Betcher of Jen-Jay, Inc, the company hired to engineer the new pipe, told the board that state and federal agencies are satisfied with its progress, per August 10 board meeting minutes.
The new outfall may be 12 inches in diameter to allow for future expansion, and construction could begin next spring. Betcher has also recommended horizontal boring under the sea floor to avoid disturbing the area’s eelgrass beds. Cost estimates for the project have not yet been released.
The process
Light gave the Sounder a tour of the aerobic treatment plant on North Beach Road, where waste is pumped from septic tanks in the district’s service area.
There, in huge vats of frothy brown liquid, it is mixed with oxygen and a specific concentration of a certain kind of bacteria that digests human waste. As these bacteria feed and multiply, they form clumps, or “flock”, and become heavier, settling to the bottom of the tanks. This removes most of the solids from the resulting effluent, which is then allowed to flow into secondary treatment compartments, where it is disinfected with a carefully monitored chlorine solution before being discharged into the ocean. Solids are removed and sent to a landfill in Eastern Washington.
The plant’s operating permit specifies that the operator test effluent quality five days per week to determine that levels of pH, chlorine, ammonia, fecal coliform bacteria, biological oxygen demand and total suspended solids are at or under allowed percentages.
Light said the treatment process used has been around for roughly a hundred years, and while the process removes the bulk of pathogenic bacteria, the plant was not designed to remove personal care products or pharmaceuticals, now becoming a topic of increasing concern among environmental scientists. Light said many community members are surprised to learn that the plant works without filters.
A complex series of chemical and biological processes takes place in the bubbling brew.
“Treatment removes quite a few of them (PCPs and pharmaceuticals),” said Light. “The bacteria absorb them and then are taken to the landfill. Some of them are oxidized and rendered neutral. They interact with each other, and the bacteria change some into other compounds.”
