Illinois EPA Grants Provisional Variance at Request of Prairie Path Water Company (Northern Hills Sewage Treatment Plant)

SPRINGFIELD, IL -- The Illinois EPA has granted in part a provisional variance to Prairie Path Water Company (Northern Hills) from the five-day Carbonaceous Biochemical Oxygen Demand (CBOD5) and Total Suspended Solids (TSS) effluent limits in the facility's National Pollutant Discharge Elimination System Permit (NPDES Permit). The provisional variance will allow various repairs to components, including the package plant treatment system and clarifier, of the Northern Hills Sewage Treatment Plant (STP), extend the life of the STP, and improve its operations. The Illinois EPA has denied Northern Hills' request for a provisional variance from the Ammonia Nitrogen (Ammonia) effluent limit set forth in the NPDES Permit.

Prairie Path Water Company owns and operates the STP, located at 1438 West Fairview Road in Freeport (Stephenson County), that provides wastewater treatment and disposal services for the Northern Hills residential subdivision. The Northern Hills STP is permitted to discharge effluent to an unnamed tributary of the Pecatonica River pursuant to its NPDES Permit, which contains effluent limits for CBOD5, TSS, and Ammonia, among other parameters. Illinois EPA received the provisional variance request from Northern Hills on August 22, 2023, and has completed a technical review of the request. In the request, Northern Hills expects increased concentration ranges of CBOD5 and TSS only when the STP's existing final clarifier is taken offline for repairs. Northern Hills expects that the clarifier will be offline for 10 to 12 days. The Illinois EPA denied the request for a provisional variance from the Ammonia effluent limit because the Agency does not have the authority to grant a provisional variance from water quality standards.

Northern Hills must continue to monitor all parameters included in and comply with all other conditions specified in its NPDES Permit. The provisional variance will begin on October 2, 2023, and end no later than November 16, 2023. The facility must comply with all conditions included in the provisional variance including monitoring, documenting environmental conditions, and notifying Illinois EPA and the Illinois Department of Natural Resources of any unusual conditions. There are no public water supply intakes on the unnamed tributary of the Pecatonica River; therefore, no public water supplies should be affected. As a result of the dilution that must be provided, the discharge will be diluted in the unnamed tributary and the Illinois EPA does not expect any adverse environmental impacts.