Wastewater Treatment Plant Recovering from Excessive Loading
Facility in Compliance with IDNR Limits
The Sioux City Wastewater Treatment Plant (WWTP) recently experienced an upset condition related to an excessive loading of wastewater solids. Staff are investigating the cause. The WWTP is designed to separate solids from liquids, however the elevated level of solids placed abnormal stress on some critical equipment and processes which has caused the performance of the WWTP to decline temporarily. Water discharged from the WWTP is sampled daily and analyzed for various pollutants. The results from that sampling and testing need to meet certain permitted requirements. While the results from those tests are still preliminary, it is believed that the discharge permit limits were exceeded for a two to three-day period. Notification was made to Iowa Department of Natural Resources (IDNR) by phone and as is routine, a written report will be provided to IDNR.
The WWTP staff, in consultation with plant engineers and a pretreatment consultant, immediately developed a plan of action to minimize any impacts and that plan is being implemented now. Sample results appear to indicate that the WWTP is recovering already and is back into compliance with permitted limits. Quick action by WWTP staff has resulted in minimal impact to the receiving stream. Measures are already underway to further enhance the WWTP’s treatment capabilities.