By Devin Rose
A second engineering firm presented options to the River Forest village board Monday night to help trustees decide if they want to invest in a new sewer line and pump station that will alleviate flooding in the north section of the village.
Christopher Burke and Associates gave the board three options for sewer systems, including a review of a report by FluidClarity, the water services firm that gave trustees the first opinion in the spring.
FluidClarity had recommended upgrading the Elmwood Park outfall sewer that runs in North Avenue to a 10-year storm frequency capacity, which would provide more room for storm water. Currently, that sewer holds waste from Chicago, Elmwood Park and the area north of Division Street in River Forest, and can't handle more than a common rainfall without flooding.
Burke said Monday that FluidClarity's project was feasible as long as the Deep Tunnel system is open. But if a storm occurs during one of about 26 times a year that the system is closed and cannot provide an outlet for runoff, street and home flooding could occur. Burke estimated the cost for that project, including a new main sewer line and laterals, to be $16.9 million, up from FluidClarity's estimate of $11.5 million. Burke said there was a difference because the system would combine storm and sanitary water, and would therefore need additional service adjustments.
Another alternative Burke presented was a separate storm sewer that would discharge storm runoff to the Des Plaines River. That system would eliminate the dependence on the Deep Tunnel system and the Terminal Reservoir, a water-holding system that will be completed in 2029. Minor street flooding would still be expected in lower locations for larger storms. It would cost about $19.1 million, according to the presentation.
The least expensive option, at $5.3 million, would have a new mainline sewer constructed in North Avenue and no construction of lateral combined sewers.
Burke also said that a 400-cubic-feet-per-second, or cfs, pump station at the end of a 78-inch Lake Street relief sewer would be too large. FluidClarity's modeling indicates the relief sewer has a maximum capacity of 225 cfs, according to Burke.
Board members said input from residents of the affected area would be useful before a decision is made to proceed with any of the options. The board asked Burke if he could provide more information at their Dec. 10 meeting.
Answer Book 2018
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