Brookfield trustees signaled their interest Monday, Feb. 24, in pursuing a plan to build a pump station along with facilities for both underground and surface storm-water storage in the vicinity of Forest and Washington avenues.
If built, the entire project would cost an estimated $2 million but would bring relief to the roughly two dozen homeowners in the area whose homes risk flooding when the storm sewers back up into the streets during high-intensity rainstorms.
“The question is, do we address this?” asked Village President Kit Ketchmark. “We can leave it the way it is … or we can deal with it and build some sort of pump to get it out of there.”
The area around the intersection of Prairie and Washington and the 3500 block of Forest Avenue, in particular, have suffered extensive flooding on at least three occasions since 2008.
In those cases, Salt Creek overtopped its banks, but by the time that happened much of the damage had already been done. A pump station and storm-water storage facilities would buy some time in those types of events and would prevent completely street flooding when Salt Creek remains safely within its banks.
“By staying dry, it gives the village and residents additional time to flood-fight,” said Derek Treichel, the village’s engineer.
A pump station would also allow the village to pump water away from the area quickly — in hours instead of days — once the river begins to recede after flood events.
What the village board is recommending as a solution is contained in a report completed last year by Hancock Engineering and delivered to the village board, Feb. 24.
The project includes a pump station that would be located underground in an area north of Washington Avenue and just west of Salt Creek. The pump would have a capacity to eject 5,000 gallons per minute (enough capacity to address a high-intensity, short-duration event that would bring an inch of rainfall within 10 minutes) from the storm sewer system into Salt Creek.
While the pumps would be located below grade, a natural gas generator, which would start in the event of a power outage, would be located above ground at the location. A fenced-off area measuring about 8 x 15 feet would be needed to house the generator.
In addition, the village would build an underground 120,000-gallon water storage vault beneath the north side of Washington Avenue, running west from Forest Avenue. Finally, the village is proposing constructing a 10-foot-deep, 150,000-gallon storm-water retention area, probably on the west side of the 3500 block of Forest Avenue, where the street is at its lowest point.
In order for that facility to be built, the village would have to acquire at least two adjacent properties in that area. Whether the village will be able to do that is not certain. If not, the village would build the pump station and underground storage vault.
The surface storage area would allow the streets in the area to stay dry in the event of a storm that dumped 5.5 inches of rain within 24 hours, along with embedded high-intensity rains. That’s the kind of storm that hit the area in April 2013.
What the system won’t be able to prevent is flooding resulting from Salt Creek overflowing. If that happens, the pump station would be turned off.
“Once the water overtops the banks, the pumps will not be able to keep up,” said Treichel. “But we will be able to pump it out quicker [when the water recedes].”
Treichel said that pumping storm sewer overflow into Salt Creek will not have any noticeable impact on the level of the river. Compared to the amount of runoff flowing into the entire Salt Creek watershed, Brookfield’s local runoff won’t have much impact.
“We have the right to pump it,” said Treichel. “Other villages are doing it. Villages are allowed to protect themselves.”
Village officials set aside $500,000 in Brookfield’s 2014 budget for the pump station, but it’s unlikely any work would begin this year. The village will seek grant funding from the Metropolitan Water Reclamation District of Cook County, which is providing funding for projects that address local flooding issues.
Brookfield applied for a similar grant in 2013, but wasn’t successful. However, said Treichel, the village has been encouraged to reapply for a grant in 2014 by the MWRD. The grants typically cover between 50 and 75 percent of the total cost of flood-control projects, said Treichel.
If the village is successful in obtaining an MWRD grant, construction on the project could begin sometime in 2015.
In the meantime, the Brookfield village board is expected to approve spending up to $175,000 for construction design engineering. Treichel said an agreement to that effect should be before the village board sometime this month.
Any money for the project would come from reserves in the village’s water and sewer fund.
Last year, the village commissioned Hancock Engineering to complete drainage study of the area near the Washington and Prairie intersection and provide possible solutions to combat flooding created when storm sewers back up.
Since the 1980s, the village has completed a number of projects that both protected the area but didn’t solve the problem of flooding.
The village raised Washington Avenue and constructed a berm on the west side of Salt Creek along the 3500 block of Forest Avenue, which helped prevent the creek from overflowing into the area. However, those improvements also served to prevent runoff reaching the river from the west.
The village also extended its network of storm sewers, much of which empties into the creek near Washington Avenue. Prior to those sewers being built, said Treichel, all of that runoff would have flowed into the village’s combined sewer system.
In heavy rain events when the Deep Tunnel system is filled to capacity and the level of Salt Creek rises, the combined sewer system backs up into basements. All of the runoff that now goes into the storm sewer system relieves some of the pressure on the combined sewer system.
Brookfield late last year also commissioned a study from a company called Living Waters Consultants to provide recommendations for improving the berm along Sat Creek on Forest Avenue.
The berm was constructed out of sandbags, which were later covered with earth, in the 1980s in the aftermath of flooding. The results of the Living Waters Consultants’ study have not been considered by the board yet.