The city’s new $4.2 million reservoir is being built on the east side of South Ninth Street. (Photo by Brad Fuqua/Philomath News)

A construction firm didn’t follow contract specifications when pouring a massive concrete slab for the city of Philomath’s reservoir June 28 — and that could be a costly error, officials said during Monday’s City Council meeting.

“Removal and replacement may be three-quarters to a million (dollars),” City Attorney Jim Brewer said during the July 10 meeting.

The council unanimously approved hiring an independent consultant, at a cost of no more than $30,000, to evaluate the slab and see if there are structural problems.

City Manager Chris Workman said that RiverBend Materials had equipment problems that led to delays and didn’t meet time requirements for the pour. At one point, the company was directing trucks to Philomath from Eugene rather than its Corvallis site, he added.

According to Workman and Brewer, RiverBend and its experts believe the concrete slab is strong enough with no defects despite the June 28 delays.

“We may end up in a litigation-type situation,” Workman said. “We may need assurances that it’s going to be fine and we may need some insurance that it’s going to be fine.”

Brewer said the slab is one solid piece of concrete that is 110 feet in diameter and more than two feet thick.

The city’s engineering firm, Westech Engineering of Salem, is worried about the slab and doesn’t believe the city of Philomath should accept the work. But that office lacks the expertise with concrete needed for a comprehensive analysis, Workman said.

“If we find flaws or defects in the slab, that will strengthen our case,” he added.

Brewer said there may be no risk of immediate failure, but concerns remain about whether the slab would last long-term.

Workman said he thought the expected lifespan of the reservoir is 50 years or more.

The city’s new $4.2 million reservoir is being built on the east side of Ninth Street and will hold 1.5 million gallons.

It’s part of a comprehensive modernization and overhaul of the city’s aging water system that includes a new treatment plant, a system to collect water from the Marys River and a high-service pump station.

Brewer acknowledged that delays for the city’s water infrastructure would result over the concrete slab situation.

HP Civil Inc. of Stayton won the $4.16 million contract for the reservoir project in November. Marion Construction Co. of Clackamas is a subcontractor on the project that sourced the concrete from RiverBend.

Kyle Odegard, who graduated from Lebanon High School and earned a degree from Portland State University, has been covering covering news as a reporter and editor in Oregon for a quarter of a century.