Illinois EPA grants Midwest Generation Joliet Station 9, Joliet Station 29, and Will County Station Provisional Variance from Discharge Requirements

Springfield—The Illinois Environmental Protection Agency (IEPA) has granted the Midwest Generation Joliet 9 and Joliet 29 and Will County power stations in Will County a provisional variance from the National Pollutant Discharge Elimination System (NPDES) water discharge permitted temperature limits, due to recent extremely warm weather conditions and high demand for electricity. 

The power stations are coal-fired electric generating facilities with steam-electric generating processes that require the use of large volumes of surface water. Will County Station is in Romeoville on the Chicago Sanitary and Ship Canal and Joliet 9 and Joliet 29 on the Des Plaines River and the facilities use circulating water that is discharged into the Lower Des Plaines River.  

Midwest Generation’s NPDES permit places limits on the temperature of the effluent based on ambient river temperatures during a given season, and gives an allowance of excursion hours it can use if its discharge exceeds the temperature.  These thermal limits are measured at the I-55 bridge over the Des Plaines River.  Without a provisional variance from the thermal provisions in the permit, all three power stations would have to be shut down, which would reduce critically-needed power availability at a time of high demand and potentially damage equipment at the plants,  according to Midwest Generation. Illinois EPA has determined that no reasonable alternatives are available and the provisional variance is appropriate.  The relief is not expected to have any long-term impacts on aquatic life, no public water supplies should be affected and no federal regulations will preclude the granting of this request. 

Midwest Generation will be required to continuously monitor the temperatures at the I-55 bridge and will provide the results to Illinois EPA and will also assess aquatic life conditions and provide documentation in the unlikely event of any adverse impacts. During the variance period, which is in effect through July 13, all other NPDES permit requirements will remain in effect.

###