District Engages Finance Advisor To Complete User Charge Rate Study

In its latest USEPA main treatment plant discharge permit, Thorn Creek Basin Sanitary District received a new, unfunded mandate to remove phosphorous from its wastewater effluent by the year 2035.  District compliance with the USEPA mandate will require physical modification of existing treatment plant processes over several years into the future.  In order to plan responsibly for these capital improvements, the District Board of Trustees approved an agreement with Ehlers Public Finance Advisors to independently review the District’s finances and to develop a user charge rate study.  This work will provide a firm foundation for financial planning and decision-making in upcoming fiscal years.

The necessary construction improvements will be completed in a series of two projects over a period of ten years.  This gradual approach will allow District staff to reliably operate treatment facilities while significant construction work occurs.  The District intends to fund both projects via IEPA low-interest loans or similar government loan instrument.  Such loans typically have 20- to 30-year repayment terms.  The District currently has one of the lowest wastewater treatment user charge rates in Illinois, which will better position customers as loan repayments are gradually incorporated into the rate structure.

The USEPA’s phosphorous removal directive was recently applied to all major Illinois wastewater treatment plants.  In response, the District conducted a series of engineering studies to identify the most cost-effective set of necessary associated plant improvements.  The first of two projects will convert the District’s anaerobic digestion and biosolids lagoon system to aerobic digestion, centrifuge drying and new biosolids storage buildings.  The second project will overhaul the District’s biological treatment process and tertiary filtration system.  Incidental miscellaneous improvements across the plant will be incorporated where they are cost-effective.

As of February 2026, two of the three phases of the financial study have been completed.  The third phase will be completed when bids are received for the first major project, so that the rate study can be updated to reflect known initial costs.  A final report will then be prepared.