Gewalt Hamilton Associates (GHA) was retained by the East Skokie Drainage District (ESDD) to address a failing storm sewer system crossing a ComEd substation which lies in the 100-year floodplain and the regulatory floodway.

ESDD initially proposed replacement of the failing storm sewer with an upsized sewer and new alignment. However, GHA proposed abandoning the sewer and excavating a naturalized drainage channel. After a lengthy and spirited negotiation process, all sides came to recognize the environmental and flood-control benefits of restoring above-ground conveyance to the Skokie River.

The design reduced stormwater velocity, erosion and sedimentation. In addition, a substantial amount of compensatory floodplain storage was provided, allowing ComEd to construct a floodwall to protect the substation. The completed design provides stable conveyance of small, frequent nuisance rainfall events as well as additional flood storage within the watershed for more severe storms.

These improvements were awarded “Lake County Stormwater Project of the Year” in 2015.