Phosphorus removal to improve over 10-year period
Showering, flushing toilets and running dishwashers in Hayden will have less of an impact on the Spokane River after the community’s sewage treatment plant undergoes major upgrades.
The Hayden Area Regional Sewer Board broke ground Friday on $14.3 million in improvements to the plant – the first phase of a $31 million project that will dramatically cut the amount of phosphorus flowing into the river.
The project is one of many that are improving sewage treatment into the Spokane River.
The U.S. Environmental Protection Agency is preparing to issue a new discharge permit for the Hayden plant this fall, which will usher in some of the nation’s strictest phosphorus controls. The Hayden plant treats wastewater at a facility on the Rathdrum Prairie and pipes it 5 miles to the river.
A low-interest state loan will pay for a portion of the plant upgrades. Hayden residents will see their monthly sewer rates increase by about $2.50 each year through 2017.
The new permit is designed to comply with the federal Clean Water Act, reducing algae blooms and protecting water quality on both Idaho and Washington stretches of the Spokane River. The stricter discharge limits also will apply to treatment plants in Coeur d’Alene and Post Falls, which are undergoing their own upgrades. Washington dischargers to the Spokane River have been operating under similar permits since 2011.
Bringing the sewage treatment plants into compliance with the new phosphorus limits is a complex and costly endeavor, said Todd Walker, chairman of the Hayden sewer board.
“We’re here on behalf of all those people who flush and don’t really understand all the work behind it,” Walker quipped at Friday’s groundbreaking.
The initial upgrades at the Hayden plant focus on beefing up the effectiveness of existing biological phosphorus controls, said Paul Klatt of J-U-B Engineering, which designed the project.
Construction of an 800,000-gallon holding tank will allow the treatment plant to gradually feed phosphorus-rich wastewater to microorganisms that take up the nutrients, Klatt said. Without the holding tank, the microorganisms get swamped during peak flows in the morning and evening, and they’re less efficient at phosphorus removal.
Through better use of the microorganisms, engineers expect phosphorus levels in the wastewater to drop tenfold, from 2 to 4 parts per million to 0.2 to 0.4 parts per million.
“That’s pretty good, but it’s still not good enough for the river,” Klatt said.
A second phase of plant upgrades will add chemical treatments designed to lower phosphorus levels even farther, to 0.02 to 0.04 parts per million.
The new phosphorus limits will be phased in over a 10-year time frame, giving plant operators time to test and refine the phosphorus-removal methods, said Ken Windram, the Hayden plant’s general manager.
TML Construction of Hayden has been hired to complete the initial plant upgrades, which will take about 18 months.
The Hayden Area Regional Sewer Board serves more than 8,000 customers in the city of Hayden, Hayden Lake and parts of unincorporated Kootenai County. In Post Falls, design work has begun on future upgrades to the city’s treatment plant, said Terry Werner, Post Falls’ public services director. The improvements will increase the plant’s overall efficiency, in preparation for additional work on phosphorus removal.
“This is sort of like the pre-wash setting on your washing machine,” Werner said. City officials eventually expect to spend about $60 million to comply with the new discharge limits, Werner said.
In Coeur d’Alene, an advanced pilot program for phosphorus removal will begin at the city’s treatment plant in late summer, said Sid Frederickson, wastewater superintendent. The pilot will treat 1 million gallons of sewage daily, but it’s designed so it can easily be ramped up to treat all of the city’s flow, he said.
The cost of complying with the new discharge permits for Coeur d’Alene is estimated at $33.5 million, Frederickson said.
The Spokane City Council earlier this month adopted a $310 million plan aimed at meeting discharge requirements in its wastewater permit that it must meet by the end of 2017. About a third of the cost will improve treatment at the city plant. The city also is building tanks to stop the flow of raw sewage into the river when it rains or snow melts.
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