Called a programmable logic controller, or PLC, the part is an electrical device used to manage various stages of water and wastewater treatment with little to no human intervention. PLCs can complete tasks such as turning pumps on and off to fill tanks and reservoirs, and pacing chemicals to meet regulations, according to the Cybersecurity and Infrastructure Security Agency.
Zooming in
Officials said the infrastructure needs to be replaced because the technology is outdated and no longer able to be supported. The PLC at Liberty Hill’s wastewater treatment plant was installed in 2009, and the typical shelf life for this type of equipment is about 15 years.
A failure of this equipment would also result in a loss of communication with the entire wastewater collection system, according to city documents. The equipment is no longer being manufactured and cannot be replaced with a like item.
“If it fails, I cannot replace it at all,” said Dewey Pierce, the supervisory control and data acquisition technician for the city’s wastewater treatment plant. “It will result in wastewater going to 24/7 operations.”
Pierce said the replacement has all upgraded software and will be supported for the foreseeable future.
What experts are saying
“This is a long time in the running here—one of our critical pieces of infrastructure is desperately needing to be replaced,” Pierce said.
A quick note
The PLC was originally slated to be replaced through another project. However, Pierce said it would be more cost effective for the city to pay for it separately rather than going through multiple contractors. This method saves the city $80,000.
