WCW24

November 1, 2023, was a relatively normal day at the City of Red Deer's wastewater treatment plant (WWTP). A portion of the WWTP was shut down to upgrade electrical components that were at the end of their service life. Following completion of the work, as electrical loads were being reconnected a fire occurred in the yet to be replaced main electrical switchgear. Red Deer Emergency Services responded quickly and put out the fire. Within an hour of the fire being put out, a meeting of all WWTP staff on site was convened to evaluate the operational impacts to the WWTP. While the plant has back up power, most of it is routed through the switchgear where the fire occurred. As a result, a large portion of the plant was without power including the aeration blowers for 50% of the available plant bioreactor capacity and most of the solids handling processes. Further, the loss of the switchgear impacted the laboratory, administration building and the plant entrance gates. A list of operational priorities and a series of supporting tactics to accomplish the priorities were developed. The highest priority was getting the aeration and pumping systems for the bioreactors and secondary clarifiers back on-line. The contractor that was upgrading the electrical components had a mobile switchgear on site that they had been using while components were upgraded. Fortunately, the contractor allowed us to use their mobile switchgear until the contractor was able to complete a permanent replacement of the burnt-up switchgear. While the repairs were underway, the operations staff contacted our regional customers to try and limit the amount of wastewater they were discharging. A portion of the wastewater flow was diverted to three on-site equalization lagoons to avoid overloading the bioreactors that were not impacted by the fire. A more robust monitoring program including increased nutrient testing frequency and microscopic observation of the biomass was carried out for the first week after the fire. Thanks to the efforts of plant electrical and instrumentation staff and the electrical contractor, aeration was restored in 17 hours and the bioreactor and clarifier mechanical systems were fully operational in 27 hours. All electrical systems were back on-line within 48 hours. Thanks to the operators and lab staff, the WWTP came through the event with minimal impact on treatment and very minor reporting violations under our Alberta Environment and Protected Areas operating approval. The presentation will discuss in greater detail the cause of the fire, the response steps taken and how the recovery went.