BACKGROUND: Administrative Consent Order
In 2012, the United States Environmental Protection Agency (US EPA) served Decatur with an Administrative Consent Order (ACO), requiring the City to eliminate overflows and reduce basement backups. The City retained outside legal counsel with expertise and direct experience in US EPA administration of the Clean Water Act. With the assistance of outside counsel and AECOM, extensive negotiations between the City and the US EPA resulted in the US EPA’s issuance of an ACO that was greatly limited in scope compared to the initial Order. This was in large measure due to the City’s ongoing commitment to improving its sanitary sewer systems, and its good faith efforts to negotiate a reasonable ACO with the US EPA.
The Administrative Consent Order’s major requirements includes:
1. The development of a Capacity Management, Operations, and Maintenance (CMOM) program. The CMOM program provides a comprehensive review of the City’s sewer collection system, including system management, maintenance, and capital improvement funding. The City’s CMOM program was approved by the USEPA on May 1, 2018 and has been implemented as required by the ACO.
2. The preparation of a Sewer Collection System Alternatives Analysis (SCSAA) for areas identified to be experiencing Sanitary Sewer Overflows (SSOs) and sewer back-ups during storm events. This analysis is focused on keeping storm water from entering into the separate sanitary sewer system and to better manage stormwater entering the combined sewer system.
US EPA Administrative Consent Order Status
The current version of the City’s Sanitary Sewer Collection System Analysis (SCSAA) identified four top priority areas of the City experiencing high inflow and infiltration during storm events. It should be noted that these are not the only areas in the City with high rain induced sewer problems, but these are the highest priority areas:
- North Lost Bridge Area
- Florian Avenue Area
- Grand and Oakland Area (Basin 5&6 in the SCSAA)
- Ellen / Division Area
The Oakland and Grand area was identified in the SCSAA due to its history of wet weather basement backups. The predominant cause of basement backups in this area is the combined sanitary sewers where both sanitary sewage and storm water are carried in the same pipe. Combined sewers still serve nearly 40% of the City, mostly in the older areas. The Grand and Oakland area is the only location on the high priority list that is served by combined sewers.
The City has not received any correspondence regarding the SCSAA from the USEPA since the current version was submitted on November 30, 2017. The plan has still not received final approval; however, following discussions with the City Council in the fall of 2020, it was determined to move forward in addressing the four priority sewer problems. The design process for each area follows this general pattern:
- Start with a preliminary review to determine the scope of the inflow and infiltration problems in an area and identify options to address them.
- Using the results of the preliminary review, complete a final design, including contract drawings and specifications for bidding.
- Bid and award the project.
- Complete the project.
- Review the system to determine if enough inflow and infiltration was removed. If necessary take additional steps.
The table below provides the project status of each priority area.
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Project Name
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Preliminary Design
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Final Design
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1
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North Lost Bridge Area Preliminary Study
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Completed in 2017
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2
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Florian Ave Area Preliminary Study
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Completed in 2017
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3
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Oakland and Grand Area
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Proposed Begin 2021
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4
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Ellen and Division Preliminary Study
Ellen and Division Final Design
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Completed in 2018
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75% Complete
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Professional Services Agreement
The October 2020 storm and sanitary sewer study session with the City Council provided direction to City staff to proceed with the Ellen/Division and Oakland/Grand Areas. The Ellen and Division Inflow and Infiltration (I&I) Reduction Project final design is approximately 75% complete. It is planned to advertise the project for bid late summer.
The Grand and Oakland Sewer Separation Study will review the combined sewer area shown on the attached location map. This area was identified in the SCSAA due to it having one of the highest clusters of wet weather basement backups. The combined sewer network in this area is undersized compared to many other combined sewer areas. The project corridor is in an older urban area and it is expected to require detailed coordination with IDOT, the Norfolk Southern Railroad, the Sanitary District of Decatur, and the Decatur Park District.
The Agreement with AECOM will provide the following services.
- Evaluation of the existing drainage system – AECOM will review and calculate the drainage requirements of the Oakland and Grand drainage area, identified as Basins 5 & 6 in the SCSAA.
- Review of televised sewer inspections.
- Prepare options and alternatives - AECOM will provide options to fully and partially separate the area to reduce basement backups. Hydraulic modeling of the existing combined sewer system may be required depending on the selected alternative.
- Meeting with stake holders - Meetings with IDOT, Sanitary District of Decatur, Decatur Park District, Norfolk Southern and Public may be required in the determination of options.
- Final Report - A final report will be provided detailing the findings and providing a recommended alternative. This final report will be the basis of determining the scope of services for a final design agreement.
The cost for the preliminary design is not to exceed $199,146.