Harrison Township approves engineering for pump station reconstructions

By: Kristyne E. Demske | Mount Clemens - Clinton - Harrison Journal | Published October 27, 2021


HARRISON TOWNSHIP — The Prentiss and Venetian sanitary pump stations will be reconstructed in an effort to improve and update their configurations to make them safer and more environmentally friendly.

The Board of Trustees voted Oct. 12 to approve reconstruction projects at both of those pump stations, continuing work to update the township’s sanitary infrastructure, making it more standardized throughout Harrison Township.

The Venetian Pump Station, built in the early 1970s, serves about 2,100 residents along South River Road east of Macomber Street, including all of Huron Pointe. It discharges into a force main that crosses under the Black Creek to a gravity sewer system in the Lake St. Clair Metropark that then flows west to the Prentiss Pump Station.

The pump station is a dry well/wet well configuration, with the pumps and controls 25 feet below grade in the dry well, so operators must climb down a ladder to access them. Currently, the station does not have a connection for an emergency bypass pump to be able to access the force main in the event of failure, something that led to Harrison Township having to decide between either bypassing the pump directly into the Black Creek or allowing basements to flood during a high-water event in 2019.

“That was a major sore spot. That’s the first time in my history here — of 23 years — that something like that had to take place, and it was due to the high water levels and, understandably, people not wanting their houses flooded,” Public Services Director David Axtell said. “Many (residential sump pumps) were pumping into the sanitary sewer, overtaxing the station (and) we had no way to bypass this station, so (we) had to use a gas-powered pump and pump it into the waterways, which is not something that is the norm for Harrison Township.

“It’s not something I want to have happen again.”

Reconstruction of the Venetian Pump Station will include replacement of the existing centrifugal pumps in the dry well and the relocation of the pump station controls to an above-grade panel. Wade Trim Associates will evaluate dry well submersible pumps and make a recommendation to the township. There will also be plans drawn up for a new valve vault to be constructed that will accommodate an emergency pump connection to the force main, in case emergency bypass pumping is needed again. The existing force main below the Black Creek will also be replaced.

“They will become submersible pumps, on slide tracks that can be pulled from above,” Axtell explained at the Oct. 12 meeting of the Board of Trustees. “The operating panels will also be above ground, making it a much safer operation and a much more efficient operation, as far as electrical usage and pumping.”

In an interview after the meeting, Supervisor Kenneth Verkest explained that the pump stations were not designed to handle storm water. Through either infiltration of ground water seeping into the pipe or illicit connections, the capacity limit can be reached.

“I certainly wouldn’t point to any one individual, but we have repeatedly found evidence where folks say, ‘I’m just going to tie my sump pump into the sanitary sewer system’ (or), ‘I’ll put a drain in my garage’ because the sanitary system flows constantly,’ but if you’re trying to gravity drain storm water and the place is already full of water, it won’t go anywhere.”

Verkest explained that those illegal connections would lead to increased flow overwhelming the system.

The Prentiss Pump Station, built in the late 1960s, is the second largest in the township, serving 4,000 residents. Its service area includes undeveloped property, but there is not sufficient capacity to accommodate any development. It receives flow from Selfridge Air National Guard Base and, because of that, experiences periods of very high flows. Like the Venetian Pump Station, the controls are below ground in the dry well, so proposed improvements include replacing the existing dry well centrifugal pumps with submersible pumps in the wet well and bringing the controls to the surface. The new pumps will be sized for existing and projected future flows.

Verkest pointed out that Wade Trim Associates has been designing several of the other replacement stations in the township and they were looking for consistency in the reconstructions.

“They were all built at separate times, designed and engineered differently, so each one is very diverse,” he said. “The thought is, we want to try to standardize these as much as possible so that, in some cases, we may even be able to have pumps on the shelf, knowing that the pumps go in on almost a railroad-type system ... If we had a pump fail, they would be able to pull a pump and replace it with a pump that’s on the shelf and then go about the business of either purchasing or repairing the pump that failed.”

The engineering cost for the Venetian Station was bid at $58,000, which includes $11,000 for soil borings and geotechnical engineering. Axtell said the Venetian Station work will cost more because of the need to replace the line under the Black Creek to include the valve vault, “so we won’t have this happening to us again, contaminating the waterways.”

“We’re on a great path, moving forward.”

The engineering cost for Prentiss Pump Station is $43,500.

Axtell said it would be about 12 weeks to get the engineering completed on the projects and that, once the work is put out to bid and the structures ordered, he hoped construction could start by mid-2022.

Verkest said the township is adding backup generators that run off natural gas in case of a power outage each time they renovate a pump station. The projects are being paid for with money in the sewer fund.