Village of Northbrook
BLA provided Phase II and III engineering for a 72-inch storm sewer through utility-congested right-of-way to help alleviate Northbrook’s significant chronic flooding along Shermer Road. The project included a micro-tunnel auger of an 87.5-inch steel casing sleeve under the Metra railroad tracks followed by pulling a 64-inch ductile iron pipe through the new casing pipe. Two transmission main watermains, a 30-inch prestressed cylindrical concrete pipe and a 16-inch ductile iron pipe both ran parallel to the storm sewer and crossed in several locations. Because of the size of the pipe, traditional circular manholes were not feasible; BLA custom-designed several box structures to facilitate pipe size and directional changes. A 72-inch backflow preventer was installed at the outlet to the West Fork North Branch Chicago River in order to prevent tailwater from backing up into the new sewer system.