The Utilities Committee met 09/24/2024. They spent around 15 minutes receiving and discussing the final update pertaining to the 12/26/2022 Polymer Incident at the wastewater treatment plant. During that incident, 4-5 months’ worth of treatment chemicals were dumped into the wastewater treatment plant’s system which temporarily stopped their digesters and the hauled waste program.
The last report given to the committee on the matter was June of 2023 in which then Utilities Director Chris Shaw talked about some of the procedural changes that they were implementing in order to prevent such an incident happening again in the future. At that time, he also provided an estimate of costs and revenue losses associated with the incident.
This September 2024 update provided by Utilities Director Chris Stempa provided a more accurate estimate on associated costs and lost revenue. He was also able to report that the remaining waste polymer left over from the incident had been successfully processed.
I’ve prepared a transcript of the discussion for download:
The overall estimated cost to the city of the incident was $352,547. This included staff time, outside contractors, the loss of polymer, and natural gas purchases that were necessary because for two months the plant was not utilizing biogas from the digesters the way it normally did. The inability to utilizing biogas for two months while the digesters were down meant they had to purchase around $50,000 more of natural gas then they usually consumed.
Additionally, the revenue they took in through the hauled waste program decreased for the two months they could not run that program, and amounted to around $140,000 in lost revenue.
They also ended up having to spend around $18,000 to process the waste polymer that was left over from the incident. If I understood Director Stempa correctly, they did this by slowly feeding the polymer waste into the plant’s dewatering operation. They had initially expected this process to take around a year and a half, but it ended up taking less than 7 months which was very nice because the polymer waste smelled quite bad. This process did require staff time and attention as well as the purchase of some ancillary materials such as pipes to create work-arounds with the plant’s existing equipment. Director Stempa noted that if they had had to rely on a hazardous waste cleaning service, the cost would have been over $100,000, whereas handling it in-house had resulted in only $18,000 in costs.
Finally, there had been around $46,000 in costs that had not been incurred during the 2 months the hauled waste program was shut down. Although they did not bring in revenue through the program during those months, they also didn’t need to pay the operating costs associated with it.
Alderperson Chad Doran (District 15) asked what plans had been put in place to prevent such an incident from happening again in the future. Director Stempa said that after the incident investigate was completed, they had immediately posted more explicit signage at the plant. They also revamped some of the internal procedures and protocols.
Additionally, they were working on fully changing their training and refresher training programs. He noted that they did not have the same kind of structure that they had a decade ago. There was a lot more turnover in employees, and it was a large and complex facility with a lot of truck traffic as well as, currently, construction work taking place. “The larger task is really now and moving forward, having a training program that matches the experience levels of the people that are working at our facility.”
Alderperson Patrick Hayden (District 7) asked about the possibility of installing a second digester because it seemed like that had the potential to increase the revenue produced through the hauled waste program and a new digester might be able to pay for itself rather quickly.
Director Stempa said there had been discussions about that, but it sounded like doing such a thing would be more complicated that merely installing a second digester. The wastewater treatment plant has been built to handle the amount of waste that it expects to have to process, so there would only be so much waste available to process regardless of the number of digesters. Additionally, installing another digester would require excavating and relocating parts of buildings.
View full meeting details and video here: https://cityofappleton.legistar.com/MeetingDetail.aspx?ID=1204448&GUID=D17B8E33-72AA-410A-A193-FABBFBE500A8
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