As reported by the Review last week, Christopher Burke Engineering (CBE) presented the Forest Park Village Council with an extensive sewer system and flooding prevention report at its July 27 meeting. Although not a problem unique to Forest Park, flooding has consistently been a community issue during Mayor Anthony Calderone’s tenure. In the report, commissioned by Calderone in late 2014, CBE used computer models to individually assess the north, south and middle sections of town.
Although the village’s entire sewer system suffers from “inadequate pipe capacity” and lack of a comprehensive “separated” sewer system, the report offers unique remedies, varying in cost and scale, for each distinct geographical area.
As a result of piecemeal construction projects over many years, Forest Park’s sewer system resembles a patchwork of piping. For instance, in the northern 325 acres of town, which the report refers to as “Area 1,” there are 110 acres of separated sewers. However, in the middle part of town, “Area 2,” the entire 275-acre section uses a combined system.
Separated sewer systems are generally able to accommodate heavy rainfall more effectively than combined systems because two distinct pipes are used — one for sanitary and the other for storm water runoff.
The report also mentions that Forest Park’s current system offers a level of flood protection that is “less than a 1-year storm event.” In the report, a 1-year, 10-year and 100-year storm event respectively have a 100%, 10% and 1% chance of occurring annually. In other words, Forest Park residents can expect to experience some flooding on a yearly basis.
To assess the effectiveness of each construction option, CBE used both a 10-year storm event and a July 2010 storm as benchmarks to demonstrate the need for reduction in flooding. James Amelio, a project manager at CBE, told the Review that costs were determined using data from similar construction projects in neighboring communities.
For Area 1, which is bounded by Harlem Avenue, Lake Street, Desplaines Avenue and I-290, CBE suggested three different construction options. The first, which is estimated to cost $12.6 million, recommends converting the existing combined sewer running along the Prairie Path into a dedicated storm sewer and installing new piping as needed to transition to a completely separated system. According to the report, if implemented, Area 1 would see a 13% reduction in flooding during a 10-year-storm event.
The second option is very similar to the first, but instead calls for an entirely new 96-inch pipe along the Prairie Path. This option would cost $17.4 million but would see a 17% reduction in flooding during a 10-year storm event.
Comparing the two options, Christopher Burke, founder and president of CBE, said, “You can see there is a modest benefit to doing [option 2]. We don’t see a significant reduction [in flooding] … but we do see a significant increase in price.”
Option 3 calls for eliminating all combined sewers by installing new storm sewers. This option is vastly more expensive, $34.7 million, but also would reduce flooding in a 10-year storm by 79%.
For Area 2, which is bounded by Harlem Avenue, Harrison Street, Roosevelt Road and Desplaines Avenue, CBE developed four construction alternatives. The first involves converting Roosevelt Road’s existing combined system to be exclusively used for storm runoff, building a storage basin and pump station at the corner of Roosevelt Road and Desplaines Avenue and installing new storm sewers throughout the area. This option is estimated to cost around $37 million and would reduce flooding in a 10-year storm by roughly 86%.
A second $21.2 million option forgoes constructing the storage basin and pump station but would still reduce flooding by 72%. Options 3 and 4 call for entirely new storm piping along Roosevelt Road and would cost $46.4 and $30.6 million respectively and reduce flooding by 95% and 88%. Option 3 is comparatively more expensive because it includes constructing the pump station and storage basin.
For Area 3, which covers 80 acres in the southern part of town, CBE recommends a single $9.3 million option that consists of enlarging the existing system while also completely separating the storm and sanitary piping. The report does not specifically mention a percent reduction in flooding but states that the project would “provide 10-year-level protection from street flooding.”
Regardless of which options the village selects, Burke was careful to note that other factors will influence flood-prevention efforts moving forward.
“We obviously need permits … [and] coordination and cooperation with the MWRD [Metropolitan Water Reclamation District of Chicago]. … They’ve always been cooperative with communities in this area [but] they are trying to implement projects of their own.”
He also mentioned possible collaboration with the U.S. Army Corps of Engineers, the Illinois Department of Natural Resources (IDNR) and possibly the Illinois Department of Transportation (IDOT).