Rigby begins moving forward with wastewater test on money-saving technology

The City of Rigby is moving forward with a pilot test for a wastewater treatment technology that could save the city more than $4 million (S$5.4 million) on upgrades to the city’s sewage plant.

The test on Nuvoda technology will cost the city an estimated $100,000 to $200,000 ($134,606 to S$269,212) in non-refundable costs and would cause Rigby to miss an Environmental Protection Agency milestone deadline of Dec. 1, 2020. Rigby City Council had elected to wait on a decision until hearing back from the Idaho Department of Environmental Quality (IDEQ) on what the ramifications of missing that deadline would be.

IDEQ has since indicated the milestone could be moved to May 1, 2021 to accommodate the Nuvoda study. In an email to Marvin Fielding of Keller Associates from A. J. Maupin with the Idaho Department of Environmental Quality (IDEQ), Maupin indicated IDEQ would likely be able to accommodate for the study. Maupin wrote that an official request to move the milestone would need to be submitted to IDEQ. He wrote “Since the City wishes to move an interim compliance date more than 120 days, this permit modification must be processed as a major modification” and would need to be opened for a 30-day public comment period.

The city previously approved moving forward with an $18 million (S$24.2 million) addition of two oxidation ditches to the wastewater treatment plant that would put Rigby in compliance with Environmental Protection Agency ammonia standards. Nuvoda would cost $13.4 million (S$18 million), but Marvin Fielding with Keller Associates indicated additional testing would be needed.

The test itself is expected to cost the city $100,000 to $200,000 ($134,606 to S$269,212) in non-refundable costs, including engineering, screen installation, a $20,000 (S$26,919.80) deposit, additional water quality testing and more. Marvin Fielding with Keller Associates told the city council last month the risk would likely be around $100,000 (S$134,606).

Fielding said those at Nuvoda have expressed their confidence that the test will work. Fielding has also said Keller Associates would not suggest moving forward with the pilot test if the technology were not promising.

Rigby Mayor Jason Richardson and a few city council members expressed hesitation at the risk the city would be taking.

“I’m just thinking, ‘Are we about to spend $200,000 (S$269,212) and end up spending an extra $4 million (S$5.4 million) anyway?’” Richardson said. “I’m just so leery of the cold stopping things for these guys.”

A somewhat similar technology, integrated fixed-film activated sludge (IFAS) has been shown not to work well in low temperatures. Richardson said he would prefer if Nuvoda took on an additional $20,000 (S$26,919.80) of the risk of the system not working.

Fielding said those with Nuvoda told him that in Northfield, the technology was working at temperatures as low as 10 degrees Celsius. He said that is typical for Rigby, though he said temperatures have dropped to around eight degrees Celsius some winters.

Council member Doug Burke said $200,000 (S$269,212) is a lot of money, but he said it might be worth the risk. Council member Blake Davis said the addition of two oxidation ditches could end up costing more than expected.

“Our estimate is around $18 million (S$24.2 million), but one issue could make it go $18.2 million (S$24.5 million) really easy,” Davis said. A few other council members murmured their agreement.

Council members ultimately approved Keller Associates as engineers for the project, and voted to explore having Nuvoda take an additional $20,000 (S$26,919.80) of risk in the pilot study agreement. If that agreement is approved, the study is expected to begin July 1, 2020 and end March 31, 2021. The goal of the study is to determine how the technology will work during winter conditions in Rigby.

If the study works, Rigby will be required to either purchase the system minus what the city already spent, or pay Nuvoda an additional $45,000 (S$60,567.75), based on a proposed agreement.

Meanwhile, the city has also approved to send out requests for proposal to seek judicial confirmation to fund the project. The council previously decided to seek judicial confirmation rather than holding a bond election to get the funding. Richardson said a legal firm will need to be hired to help with the process.