R2018-13 Professional Services Agreement AECOM for Ellen and Division Inflow and Infiltration Reduction

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A.�M 303 E.Wacker or. Exhibit A-1 Suite 1400 Chicago,IL 60601 312-373-7700 tel January11, 2018 Paul Caswell, PE Assistant City Engineer City of Decatur Public Works Department #1 Gary K Anderson Plaza-3rd Floor Decatur, Illinois 62523 Regarding: Ellen and Division—Inflow and Infiltration(181) Program Scope of Work Dear Mr. Caswell: AECOM Technical Services, Inc. (AECOM) is pleased to provide this scope of work(Scope)for the above-referenced project. This Scope encompasses AECOM's engineering and field services for the subject project. Note that a detailed breakdown of task costs and a schedule is included in this Scope. Background The City is currently under Administrative Consent Order (ACO) by the United States Environmental Protection Agency (USEPA). The ACO requires a reduction in basement backups within the City's combined and sanitary sewer system, as well as the elimination of all unauthorized Combined Sewer Overflows (CSOs)and Sanitary Sewer Overflows (SSOs). In order to demonstrate compliance with the ACO, the City was required to submit a Sewer Collection System Alternatives Analysis (SCSAA). In partnership with AECOM, the SCSAA (and subsequent revisions)were submitted on April 12, 2016, November 4, 2016, and November 30, 2017. As a part of this work, it became clear that the reoccurring SSOs at Manhole No. 10-13 in the Ellen and Division area (see attached Figure A) could not be eliminated through regular maintenance. Therefore, additional study is needed to eliminate this SSO, either by reducing 1/1 or removing hydraulic deficiencies(or both). SCOPE OF WORK Our scope of work will be as follows: Task 1: HYDRAULIC AND HYDROLOGIC MODELING The purpose of this task is to perform hydrologic and hydraulic modeling of the Ellen and Division study area. This modeling will be used to better understand performance of the local sewer collection system and assess options to prevent the reoccurring SSOs at Manhole No. 10-13, as well as any other manholes for which the model predicts SSOs. A hydraulic model of the drainage collection system will be developed using the Personal Computer Storm Water Management Model(PCSWMM) package. AECOM has previously used PCSWMM to analyze other reaches of the City of Decatur collection system, including Basins 5 and 6.