A Glen Ellyn village consultant will be investigating ways to increase the rate at which stormwater leaves Lake Ellyn as one possible solution to reduce flooding in the neighborhood around the lake.
Glen Ellyn officials have been looking to increase the discharge rate of the lake from its current level of 37 cubic feet per second to at least 61.4 cubic feet per second, which is the current maximum rate allowable under DuPage County's stormwater regulations.
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Increasing the rate would allow the lake to discharge up to 40 million gallons of water per day, from its current amount of 24 million gallons per day.
Officials from the village and county are currently in discussions to increase the rate even further, perhaps to 85 cubic feet per second.
But first, officials say studies must be done to evaluate the impact that a discharge rate increase could have upon downstream areas.
On Monday, the village board unanimously approved a $38,000 engineering services agreement with Warrenville-based Engineering Resource Associates to determine the peak discharge rate of the lake.
It follows the hiring of another consultant in June who is designing changes to an outlet control structure that would also allow the discharge rate to be increased.
The lake is a stormwater detention facility located north of the village's downtown that releases water through underground pipes that lead to nearby Perry's Pond and the East Branch of the DuPage River.
Bob Minix, the village's professional engineer, said increases in release rates above the current level require verification that downstream areas won't be adversely impacted.
Engineers from ERA, the consultant hired Monday, will evaluate the impact of various rates by what is called FEQ modeling, a "continuous flow" computer simulation that will look at a variety of large and small storm events and see how downstream areas could be impacted, Minix said.
Minix said ERA is one of a select number of firms with the expertise to do such modeling, which is used by DuPage County's stormwater department.
ERA will also do modeling to see if greater storage is allowed in the East Branch of the DuPage River. That's one element of mini-watershed/flood control study that's required before the county gives consideration to raising the discharge rate above 61.4 cubic feet per second.
The consultant's work is expected to be complete by the end of the year.