Operator error causes sewage spill


STAMFORD — A Water Pollution Control Authority operator accidentally turned off the sewage treatment facility’s ultraviolet disinfection system Sunday afternoon, sending 80,000 gallons of non-disinfected wastewater into Stamford Harbor.

The UV system, which is the last step in the sewage treatment process, blasts outgoing wastewater with ultraviolet light to neutralize harmful pathogens such a e coli. The system has failed repeatedly since it was installed 10 years ago and has recently undergone extensive, expensive repairs and upgrades.

Sunday’s spill occurred when a technician from the UV system’s manufacturer, who was on site Sunday completing final repairs, asked a WPCA worker to shut down one bank of lamps so he could install new sensors, WPCA Executive Director Bill Brink said in an email Monday. The worker accidentally turned off the wrong set of lights, and as a result 80,000 of otherwise treated wastewater was not properly disinfected over the course of 12 minutes.

“This is a very unfortunate event caused by human error,” Brink wrote. “The UV equipment itself has been operating well and without incident for the past few months since the upgrades and modifications were made to the UV system.”