USEPA Imposes New Treatment Mandate

In its latest USEPA main treatment plant discharge permit, the District received a new, unfunded mandate to remove phosphorous from its wastewater.  This significant directive has been newly applied to all major Illinois wastewater treatment plants.  District compliance with the mandate will require physical modification of many aspects of the existing treatment plant processes over several years into the future.

In the last decade, USEPA has increased its focus on reducing nutrients – including phosphorous – in US waterways.  Nutrients, which enter waterways primarily from farm field fertilizer runoff, can accumulate and cause undesirable physical and biological conditions.  Surface algae blooms can form, which are a visual nuisance and potentially harmful to aquatic life.  The most significant impact of excessive nutrients can be seen at the discharge of the Mississippi River into the Gulf of Mexico, where a “dead zone” has formed that prevents aquatic life from thriving.

The deadline for District compliance is the year 2035.  The District has conducted a series of studies to identify the most cost-effective set of necessary associated plant improvements.  Complicating the District’s efforts are unique industrial pollutants entering the District’s influent wastewater, which makes biological phosphorous removal more challenging.

The necessary treatment plant improvements will be completed in a series of two projects.  This will allow plant staff to continue to operate reliably, while significant construction work occurs alongside existing treatment processes.  The first project will convert the District’s anaerobic digestion and biosolids lagoon system to aerobic digestion, centrifuge drying and a new biosolids storage building.  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.

The District plans to fund both projects via IEPA low-interest loans or similar government loan instrument.  These loans typically have 20- to 30-year repayment terms, although USEPA may offer longer repayment periods.  The District currently has one of the lowest wastewater treatment user charge rates in Illinois, which will better position customers when loan repayments are eventually incorporated into the rate structure.  Third party rate studies are included in the planning process.

All preparatory work related to the phosphorous removal mandate has proceeded under the leadership and guidance of the District Board of Trustees.  Their oversight and support of planning for this new USEPA requirement has been invaluable in ensuring that the District provides its customers efficient and reliable facilities for decades to come.