After a layoff of nearly five months due to unforeseen difficulties rerouting a water main, work has resumed at the site of what will be a new Brookfield Avenue bridge over Salt Creek.
More exactly, crews are working immediately north of Brookfield Avenue, preparing for the installation, perhaps as early as next week, of an aquadam to expose the Salt Creek riverbed so a trench can be excavated for the new water main.
There is a 16-inch water main that runs east-west under Brookfield Avenue. Because the new bridge will be so much wider than the former one, that water main needs to be rerouted north under the village hall parking lot and then west under the creek before jogging back south to reconnect with the existing Brookfield Avenue main.
The village, along with its engineering consultant, Ciorba Engineering, and its general contractor, Lorig Construction, had hoped to bore a hole beneath Salt Creek north of the bridge site for the water main.
However, after augers hit solid objects on two attempts late last summer, officials halted work in order to get permission from the Illinois Department of Transportation, which is the lead agency for the project since it involves federal grant funding.
IDOT approved the roughly $470,000 open-cut project in December. The water main re-routing effort and other change orders have pushed the total cost of the new bridge to about $4.5 million, 80 percent of which is being covered by the federal grant.
On Feb. 1 crews began drilling the first of the eight 45-foot-deep wells – four on either side of Salt Creek – in preparation for the installation of the aquadam, which had been tentatively scheduled for installation the week of Feb. 14. Heavy snow delayed the well-drilling work by two days last week.
As of the morning of Feb. 7, five of the wells – including all four on the west side of the river — had yet to be drilled. Piping and a pump were delivered to the site that morning.
According to Jesse Singer, Ciorba’s lead project engineer for the Brookfield Avenue bridge, ground water will be pumped from the wells to ensure that there will be no upwelling into the creek bed when the aquadam is installed and water pumped from that area.
“We‘re hoping for not a lot of additional snowfall,” said Singer. “The dryer it is the better.”
Pumps will be running 24 hours a day for about 10 days to drain the wells, said Singer. In the meantime, a series of eight 18-inch diesel-powered bypass pumps – six operational and two in reserve – will be set up on the east side of Salt Creek.
Workers will then install a pair of tubular aquadams, which Singer described as “big water balloons” filled with water and placed across the creek bed to define the work area. The pumps will then remove the water from the work area and then run continuously in order to divert 50,000 gallons of water per minute through three 24-inch high-density polyethylene lines to Salt Creek downstream of the south aquadam.
The pumps for both the wells and to divert Salt Creek are equipped with noise-suppressing equipment, said Singer, but noise from the pumps, which will operate 24 hours a day, is inevitable.
A notice on Brookfield’s website about the project states the sound likely will be similar to “an idling semi-trailer truck.”
Once the dams are in place and work area is dewatered, an excavator will dig a trench across the Salt Creek bed where the water main and a ComEd power line will be placed.
After the water main is tied in, it will be chlorinated and pressure tested. That work was tentatively scheduled to begin the week of Feb. 21, with a breakdown of the bypass pumps and piping, wells and aquadams scheduled for the week of Feb. 28.
The work schedule is wholly dependent on weather conditions. Heavy rain or snow likely will result in delays.
There’s plenty of work remaining once the water main is rerouted, including the demolition of the old bridge superstructure on the east side of Salt Creek and the installation of the new bridge itself.
It’s unclear exactly how long that work will take to complete. Brookfield Avenue between the village hall and Forest Avenue has been closed to traffic since last May.