The New Era - All about Sweet Home since 1929

Cost of wastewater plant improvements rises, but changes should last longer


September 2, 2020

Of The New Era

Costs for the planned wastewater treatment plant have risen about $1.9 million since the last estimate, but planners say the changes will help the plant last a lot longer.

City Council held a work session to hear about the plant's design on Tuesday, Aug. 28, because the planning is now 60 percent complete. The original plan set the cost of the plant at $42 million, but the designers from the firm MurraySmith came up with a few ways to save on building costs early on. The planning phase and regulatory review should be completed in early 2021. Construction is set to be complete in fall of 2023.

A new wastewater treatment plant is necessary because the current plant does not have sufficient capacity to cope with "peak flow," which means untreated wastewater sometimes ends up released into the river. That happens during storms, when leaks in the piping system push stormwater into the wastewater system, overwhelming the plant's current capacity.

Recent leak repairs have limited the peak flow from over 20 million gallons in a day to 12 million gallons. While those repairs helped significantly, the max capacity of the current plant is currently 7 million, meaning human waste is released into the watershed during storms.

The Oregon Department of Environmental Quality has fined Sweet Home for these releases in the past, though City Manager Ray Towry said that DEQ "has been very, very kind to us, and when we've been fined it's the absolute minimum they can fine us."

Project Manager Austin Rambin said the emphasis is on rehabilitating, reusing, and repurposing existing buildings to save money. Initial estimates for a full rebuilding were at $42 million, but have been reduced to around $30 million, which will save taxpayers money.

"We're looking at an average wastewater rate of $65 a month as opposed to $95 a month," Rambin said. Elements of the plant that will be re-used or repurposed include the influent pump station, the chlorine contact chamber, which will now be an ultraviolet light contact chamber, and the aerobic digester, among others.

Initial designs set the cost of replacing the plant at $42 million, but re-use and rehabilitation dropped the cost to $28.1 million at the 20 percent schematic design. That cost has gone up slightly since, to $30.1 million. That cost still has a built-in value contingency, so the cost could go back down as the design process continues, Public Works Director Greg Springman said.

The increased cost lies in a few important changes: The maintenance building is now separated from the thickening building, whereas they used to be combined, and the primary clarifier is getting a lid to keep odors down for the sake of neighbors. The maintenance building has been moved away from the area where all plant's filtering and clarifying processes occur, which will allow the plant to use gravity to move liquid around instead of expensive pumps. It also gives the plant space to grow if regulations change or if the population goes up and a higher capacity is needed.

Rambin said the modifications will also help with the longevity of the plant, as there's space for growth. "We're looking at 40 to 50 years," he said.

Other improvements can also save the city money: "By creating compost and not bringing biowaste to the landfill, we will save over $100,000 a year," Rambin said. Currently, solid wastes are being turned into a material similar to soil, but certain disposed items, especially feminine hygiene products, remain in the solids. The new plant will do a better job of filtering out those undesirable elements, and will get the solid waste to a state where it can be used by farmers. If that happens, the waste won't have to go to landfills, and will save the city $130,000 a year in landfill costs.

The plans also involved installing energy efficient parts, which are more expensive, but which come with energy efficiency invectives that will save the city money. "By using a more expensive blower system, you get incentives based on the amount of energy saved over the lifecycle of that blower. And that's just the first one," Rambin said. That one change saves the city $330,000 through incentives.

The plan will also see some system updates that will save a lot of time for plant operators, who are otherwise on call to come to the plant in the middle of the night. "With automation, they can do it from their couch," Rambin said.

City Councilor Dave Trask asked whether it is possible to reduce costs back to the $28 million level. "Why do we have all these different buildings?" Mayor Greg Mahler voiced similar concerns about the price increase.

Springman said it's possible to trim the costs, but it may decrease the longevity of the plant. "We were tasked with solving a problem for this community for a long time," he said. "We're looking at wood versus stainless steel, those kinds of questions."

Mahler replied, "We told the citizens originally that it would be $28.1, we've got to be able to explain that to citizens."

Towry responded, "I would start that conversation with, it was originally $42 million, with a $95 a month rate."

"We're doing very well with this project as far as dollars and cents," Springman added. "Let's not cut because we want to cut." He said the actual cost to local taxpayers may be around $11 to $12 million, not the full $30 million cost, due to grants from state and federal sources. The remaining cost of constriction will come from a USDA loan, according to Towry, and will be paid out through wastewater billing over the next several decades.

Trask said it's important to do the project well, and to not wait too long either: rehabilitating old buildings gets more expensive if they get older and deteriorate. "We don't want to cut corners. If stainless steel lasts longer than wood, we should consider that," he said.

Councilor Lisa Gourley agreed. "I just want it to be a smart build. I can understand a larger investment if it's going to be a smarter investment."

Editor's note: This version of the story corrects the numbers for the cost increase for the wastewater treatment plant. The actual cost increase was from $28.2 million to $30.1 million.


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