Motion to Finalize Scope of Proposed Work Fairview/Grand Sewer Project

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PUBLIC WORKS MEMORANDUM DATE: April 5,2023 TO: Honorable Mayor Moore Wolfe and City Council Members FROM: Scot Wrighton,City Manager Matt Newell,P.E.,Public Works Director Paul Caswell,P.E.,City Engineer SUBJECT: Oakland and Grand Area Sewer Separation Project(Basin 5/6) City Project 2021-01 This serves as a report to the City Council regarding the Oakland and Grand Area Sewer Separation Project. This inflow/infiltration reduction project is part of the City's overall response to the directives from the U.S. EPA as described in Appendix A. A design agreement with AECOM Technical Services was approved by the City Council on October 17,2022,with the direction that staff would reach out to the City's water consultant Lisa Bonnett to determine the Illinois Environmental Protection Agency's(IEPA)approach to the two alternatives presented to Council: • Alternative 3: Full separation of the storm and sanitary with a storm discharge to Steven's Creek south of Fairview Park. • Alternative 5a: Partial separation of the storm and sanitary directing storm drainage to holding ponds and releasing the storm water back into the combined sewer system over time. Illinois Environmental Protection Agency Discussion Public Works staff contacted Lisa Bonnett about getting input from the IEPA. Ms.Bonnett indicated that this was not within her expertise but did provide contacts to individuals within the organization that would be of help. She offered to make introductions if we had trouble getting to them. Following up on Ms.Bonnett's recommendations, City staff and AECOM had discussions with the IEPA which were useful and productive. We were told that there were no requirements that would prohibit the City from using holding ponds to retain storm water and then discharge it back into a combined sewer system. The IEPA did not appear willing to provide a written response,however;they were having a discussion with the Sanitary District of Decatur on the issue,who could provide a written response. Sanitary District of Decatur Discussion In discussions with the Sanitary District,it was their clear recommendation that the City pursue Alternative 3 a complete separation and not return the separated flow into the combined sewer p p P system. They followed up these discussions with a letter dated March 23,2023 (attached). The letter indicates the District's preference and outlines the difficulties that would be inherent in using holding ponds. Essentially,reintroducing storm water into the sewer system would require Page ( 1