City: Wastewater treatment plant needs updates

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SANDPOINT — The city’s wastewater treatment plant is in need of updates.

Next year the city is planning to spend $5 million to get the [wastewater treatment plant] project management started, Jennifer Stapleton, city administrator, told City Council members August, 4th, 2021.

The current plant was built in 1955 from components purchased from the Farragut Naval Station, said Stapleton. Today, over 60 years later, the primary clarifiers from the original plant are still in use.

The typical planned life of a wastewater facility is 20 years. This makes Sandpoint’s plant beyond the useful life span. In May 2017, the city and its consulting engineers began developing a new 20-year facility plan.

Other than the current treatment plant's age, Sandpoint is built on poor draining soil. When there is a high level of precipitation the groundwater levels rise quickly.

Groundwater then flows into the city’s wastewater collection system through cracks and holes in the system mains, cracked or broken lateral lines, sump pumps and road drains that are connected to the sewer system rather than the stormwater system, uncapped cleanouts and storm drain cross-connections, officials said on the website.

“When experiencing high levels of inflow and infiltration into our system, we exceed the peak flows of the city of Coeur d’Alene’s plant which is serving a population of over 50,000. Even our typical wet weather flows are the same as the peak flows experienced by cities of Post Falls and Rathdrum combined,” officials said on the website.

Sandpoint’s wastewater goes through the waste water distribution system to the treatment plant before it is discharged into the Pend Oreille River. Treatment of wastewater reduces the amount of pollutants that are discharged back into the environment, said city officials.

According to data from the University of Nebraska-Lincoln Institute of Agriculture and Natural Resource, all wastewater must be treated and disinfected prior to use and cannot be discharged to the land, or to surface or groundwater.

“The reduction of the amount of pollutants discharged into the Pend Oreille River is of utmost importance and critical to the health of the river and anyone downstream that uses the water,” Sandpoint officials said on the city’s website.

The city said, up until the middle of the 20th century, dilution was the “solution to pollution.” The larger populations grew, the more apparent it became that waters were taking in more pollution than they could naturally treat.

The plan for the new plant must address hydraulic capacity, treatment capacity, project financing and operations and maintenance considerations to determine the effects of a project on the overall wastewater infrastructure, as required by the state of Idaho, said Stapleton.

The total projected cost for the updated wastewater treatment plant is $50 to $70 million dollars. The next step is seeing how the city can grow the system beyond the city limits, Stapleton said.

“[The city has] entered into multiple agreements with rural districts and discussions with Kootenai/Ponderay Sewer District for potential interconnectivity into our wastewater treatment plant,” she added. "This could be a win-win for ratepayers in both systems and could be environmentally positive for our areas.”

If the budget plans for fiscal year 2022 pass then the city plans to finish the updates on the new wastewater treatment plant by 2027.