Dual-chambered reservoir approved for alternate bid
After many questions regarding a proposed change in the replacement of the city’s 1 million gallon water reservoir that also brought a higher price tag, the Washington City Council Wednesday approved letting the design for a dual-chambered reservoir as an alternate bid to the project.
Council member Bob Shellmyer voted against the motion to bid the design with the single chamber design for the ground storage water reservoir that is on track to be replaced in the spring. During discussion he asked Fox Engineering firm engineer Steve Troyer many questions about the firm’s history in designing dual-chambered reservoirs. Troyer said that Fox had not designed such a reservoir before, but many were in use.
“Having a concentric tank within a tank – there is no concern on my behalf,” Troyer said. “Saying it hasn’t been done before – it has been done before, not by us and I’m not sure if there is anyone in the state who has used this concept — but it has been used before.”
Troyer said that he would provide Shellmyer with a list of cities that use dual-chamber reservoirs.
The bids are expected to be let for a winter bidding. The council will decide after the bids are received whether to go with a single or dual chamber.
According to the design, the reservoir would be divided into two parts that would each hold 500,000 gallons. The design of the reservoir is circular to maximize water flow, and the second chamber would also be a circular chamber located inside the main chamber. The dual-chambered design is expected to cost about $280,000 more. The benefit would be that one chamber could be taken out of service for cleaning or maintenance without disrupting the system.
City administrator Brent Hinson said the option was not identified in the facilities plan.
“The biggest issue is that when we initially talked about it — when it was in the water facility plan – they had just included a single chamber,” Hinson said. “I was not familiar, nor was our water superintendent, about the options out there for ground storage reservoirs. We knew what we had. When Fox brought us this idea a month ago, it makes great sense.”
During discussion, the technical aspects of how the dual-chambered reservoir would improve water quality due to the flow and reduction in chances for dead spots were outlined.
“I want this design to be as DNR-proof as humanly possible,” council member Merle Hagie said. “I think it gives us much more opportunity to do so with this design. I want to do it right the first time. There have been too many mistakes when we have tried to do things cheaply before.”
Shellmyer asked if there was additional cost to the taxpayers. The initial cost of the project is expected to be about $1.35 million, while the dual-chambered reservoir is expected to be about $1.63 million.
“I want to say that while I don’t disagree with what Merle just said, I don’t like the idea of moving forward with it until I have something in my hand which tells me where one, two, or three of these are and I can make some phone calls and study how happy those people are,” Shellmyer said. “I don’t want to commit $300,000 in taxpayer funds if there is something out there that’s hidden. After that, I am willing to move forward.”
The council learned all the water feeding into Washington’s system goes through the reservoir on North Fourth Avenue. The reservoir is scheduled to be replaced due to structural problems. The new reservoir will be constructed just east of the existing reservoir.
Hinson said that Mayor Sandra Johnson had opened discussion with the Washington Historical Society about it, but he believes that demolition of the existing reservoir will be part of the project. He said that the city eventually plans to dig a new well on the site that the reservoir is currently located on.