Dirt stockpile changes could contribute to $400,000 overrun for Liberty Park stormwater tank

Engineers will ask Spokane lawmakers to dig a little deeper to cover the potential costs of trucking dirt removed in advance of burying a massive stormwater tank in Liberty Park.

Some of the mounds of earth now lining the freeway headed east out of Spokane were originally slated for a spot beneath the Hamilton Street interchange. In a report prepared for the Spokane City Council’s consideration Monday, city engineers said a verbal agreement with the Washington Department of Transportation to pile the dirt beneath the overpass fell through over concerns about the stress on road supports.

Trucking the dirt to a new location is part of the potential $400,000 in additional costs now anticipated for the $10 million project, one of several in a larger effort to reduce sewage flows into the Spokane River.

“We put the bid out, still thinking that we had a shot at that place across the street,” said Scott Simmons, the city’s public works director. “But then, before we got the bids back, we got notified that wasn’t going to be the case.”

Al Gilson, a spokesman for the Transportation Department in Spokane, said state officials tasked with reviewing road safety made the call.

“The bridge engineers in Olympia saw something they didn’t like,” Gilson said.

There were no documents signed assuring the city the overpass location would be acceptable.

“It was a discussion that was going on,” Gilson said. “There was never any formal approval.”

The contract to build a 2-million-gallon stormwater tank, tucked into the side of a bluff overlooking the East Central neighborhood park and the bustling Interstate 90 corridor, was awarded to Spokane-based Halme Construction in October 2016. The project is part of a plan to install subterranean chambers throughout town that capture rain and snowmelt before it enters the city’s combined sewer system. When there’s too much runoff in the system, the mix of rainwater and sewage flows untreated into the Spokane River.

The total cost of the stormwater tanks was estimated to be about $144 million, and includes some funding through the state’s Department of Ecology.

City engineers knew in April last year that the stockpiling plans would need to change and likely would cost close to an additional $100,000, according to city records. But that cost would have been covered under an amount of money set aside from the city’s reserve account for public projects to cover unexpected expenses during construction.

Additional issues with the project, including the requirement to buy more expensive steel and iron than anticipated, have created costs that now require lawmakers to set aside more of that reserve money than anticipated, Simmons said.

The original bid didn’t include the price for using only American-made steel and iron, a requirement to receive financial assistance from the Ecology Department. The error added another roughly $132,000 to the project above what was originally estimated.

Like many of the other tanks being built around town, including the one being burrowed into the hillside near the Downtown Spokane Library, a public green space is slated for construction above the Liberty Park chamber. Some of the soil that was removed will be returned to the site, which necessitated finding a new stockpile location nearby. The city leased a lot at Second Avenue and Madelia Street for storage of the dirt, just across the freeway from the tank site.

“We’re intending to use a lot of this back on-site,” Simmons said. “We’re trying to save the citizens costs on these projects, and not having to truck them miles and miles away. We still got a good location.”

The City Council delayed approving a similar request for more money on the work underneath Lincoln and Monroe streets downtown last fall over concerns the Public Works Department hadn’t promptly informed them of the excess expenses, putting them in a position where work had already been completed over the project’s budget without review.

Simmons said the request, which will be considered by the City Council on Monday, is intended to avoid that issue. According to the engineer’s report, roughly $7.9 million of the project’s total authorized budget of $10.6 million has been spent, with completion planned for the end of this year.

“This is a good practice for us, rather than asking for approval after the fact,” Simmons said. It’s uncertain if the full $390,000 in additional funding tied to the dirt stockpile issue will be needed.

While the Liberty Park tank may exceed the administrative reserve amount laid out for the project, other public works contracts have come in well under their allotted reserves, Simmons said. The city is averaging spending around 5 percent of its reserve funds on public works projects, and the savings on other projects will be able to cover the additional costs of the tank.