Ames wastewater treatment facility’s needed renovation could cost more than $50 million

Plans to renovate Ames' wastewater treatment facility may cost the city $8.6 million more than expected.

The Water Pollution Control Facility (WPCF) is being converted to improved nutrient removal treatment technology , which will take place over a 20-year period. The first phase of the project received only two bids, and the low bid was about $53.3 million.

The engineer's cost estimate for the project's first phase was about $44.7 million.

The Ames City Council delayed action on awarding a contract until its meeting on Aug. 13 to allow staff more time to review funding options. The council had previously delayed action until July 23.

The city will use the additional time to discuss pricing with the low bidder and explore possible changes that could reduce costs, such as identifying other projects that could be delayed and determining the impact on sewer rates if the contract is awarded to the low bidder.

How old is the city's wastewater treatment facility?

The facility's current system has performed well in what it has been designed to do, Water & Pollution Control Department Director John Dunn said.

The Water Pollution Control Facility, built in 1989 along 280 ^th Street, treats wastewater for residential, commercial and industrial operations. It is rated to handle between 8.6 million gallons and 12.1 million gallons per day with a maximum capacity of 20.4 million gallons.

The wastewater treatment facility has seven full-time employees and serves more than 18,000 homes and businesses within the city, according to cityofames.org. The operations also serve the National Centers for Animal Health, Iowa State University, and the city of Kelley.

Revenue from the city’s sewer fees covers the operation of the facility as well as new construction. No residential taxes are used to fund the operation, according to cityofames.org.

The facility recently received a Platinum 34 Peak Performance Award from the National Association of Clean Water Agencies, a recognition for 34 continuous years without a single violation of its discharge permit.

"Ames' sewer rates are currently in the lowest 25% of similar-sized systems in Iowa, based on an annual state-wide survey conducted the Ames," Dunn said. "When pairing up the Platinum 34 award with being in the lowest 25% of rates in the state, you can see how successful the Ames City Council has been in striking that balance for more than three decades."

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Project split into two phases

Splitting the WPCF's conversion into two phases allows the city to time out the necessary equipment replacement while extending the service life of other infrastructure.

The city's biggest concern is the condition of the trickling filters. Dunn said they have exceeded their useful life, and rehabilitation and replacement will cost an estimated $12 million.

"The trickling filters are the 'work horses' of the treatment plant," Dunn said. "They are integral to the plant’s performance."

Phase I will include the construction of redundant capacity, which will relieve the load on the trickling filters and extend their life until they are replaced entirely in Phase 2.

Phase I also will replace several other key pieces of equipment.

The second phase, tentatively planned to start in about 12 years, will complete the transformation to updated nutrient treatment removal technology.

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Conversion required by the state

The conversion project is necessary due to the city's permit obligation under the Iowa Nutrient Reduction Strategy. Adopted by the Iowa Department of Natural Resources in 2012, the strategy aims to reduce nutrients in Iowa waters and the Gulf of Mexico.

The liquid waste from the Water Pollution Control Facility is discharged into the South Skunk River.

Ames completed a feasibility study in 2019 evaluating the best means of achieving the strategy's goals. The Iowa DNR approved the recommendation to implement a phased program converting the WPCF.

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Celia Brocker is a government, crime, political and education reporter for the Ames Tribune. She can be reached at CBrocker@gannett.com.

This article originally appeared on Ames Tribune: Ames wastewater treatment facility’s needed renovation could cost more than $50 million