Illinois River Flood Protection

Hurricane IKE disaster floods of 2008 severely impacted the City’s wastewater treatment plant (WWTP) facility located along the Illinois and Michigan Canal adjacent to the Illinois River. Floodwaters overtopped the existing berm and inundated the plant entirely, damaging much of the infrastructure including attachments and appurtenances in the seven buildings on site, tankage throughout the facility, almost all of the electrical panels and controls, lab and office, and pump motors.

HR Green was contracted by the City to conduct preliminary design investigations, prepare contract documents, assist with bid award and provide construction administration services. The flood control protection improvements protect the WWTP up to a 500-year flood elevation. Improvements included sheet pile retaining wall, earthen levees, flood gate structures including removable flood gates, and lift station to control interior drainage and seepage through a collection system of storm sewers and toe drains. HR Green obtained permits from IDNR-OWR, coordinated with the DCEO office for an environmental clearance and assisted in coordination with the railroad for removal of a rail spur, critical in building the earthen levees on the north side of the plant.

During the design process, HR Green realized that original grant funds were not sufficient to construct the required improvements. HR Green, in partnership with the City and DCEO office secured an additional $905,000 over the original grant amount which also included replacing the effluent pumps which was not part of the original scope and grant application. Design investigations, plans and bid documents were completed on a very aggressive schedule (within 7 months from the authorization to proceed). Construction started in late September 2012 and was completed in March 2013, just a month before the April 2013 storm event. The plant remained dry during the 2013 flood event which exceeded the flood elevations of 2008 and could have been disastrous to the City had the project not been completed on an aggressive schedule. The effluent pump replacement was completed in the summer of 2015.