With concrete and landscape work largely complete on the storm water pump station facility in and around the Washington/Forest intersection, the last piece of the puzzle will be to finish the above-ground storm water detention “bowl” on the west side of the 3500 block of Forest Avenue.
On May 22, the Brookfield Village Board voted to approve spending $63,338 to shore up and regrade the 10-foot deep detention facility, whose southern and western slopes collapsed this winter.
Brookfield Village Engineer Derek Treichel said work to repair the damage is expected to begin sometime in the first two weeks of June, but that rainy weather could delay it.
Once work starts, however, it ought to progress swiftly. Treichel said the work should take four days to complete.
“We just need it to dry out a little bit and then have four days of dry weather,” Treichel told village trustees on May 22.
According to Treichel, workers will first secure a liner that is affixed to the north and east slopes of the bowl with about 300 pins that are 18 inches long and a half-inch in diameter. The liner is covered with 18 inches of top soil, and the pins will be driven through to the soil and into the clay base below the liner “to stabilize the liner and hold it to the clay,” said Treichel.
Meanwhile, the plan for the west and south slopes, which have collapsed is to build them back up with clay and then lay what’s called a “geogrid,” a plastic grid that looks something like a snow fence, on top of the regraded clay slopes.
Six inches of top soil will go on top of the geogrid and sod will be placed atop the entire bowl. The roots of the grass will grow into the geogrid, said Treichel, giving the slopes additional stability.
When Treichel last explained the structural issues with the above-ground facility on Forest Avenue back in April, he stated that about two feet of rock would be placed at the bottom of the slopes to provide more stability. However, the latest plan does not call for rock to be installed, Treichel confirmed.
Once the repair work is complete, the only thing left will be to erect the six-foot high wrought iron fence around the property. It’s unclear how the facility will be landscaped in the future to soften the look.
Last week, workers finished laying sod and planting trees on the restored parkways on the west side of Forest Avenue and along Washington Avenue. Treichel said that both electrical power for the pump station on the north side of Washington Avenue near Salt Creek and the gas service for the pump station’s generator in case of a power outage have been connected and that the pump station was now fully operational.
The pump station and storm water storage project cost about $2 million to complete, about half of which was funded by the Metropolitan Water Reclamation District of Greater Chicago. The village’s portion of the project was paid for by using cash reserves in its water and sewer enterprise fund.