Winslow Public Works Director Paul Fongemie walks past 16-inch sewer line April 10 at the Chaffee Brook Pump Station in Winslow. Construction on a new pipeline at the station hit a snag last month when a barge hit the pipe, releasing hundreds of thousands of gallons of untreated sewage into the Kennebec River. Rich Abrahamson/Morning Sentinel file

WINSLOW — Hundreds of thousands of gallons of untreated sewage spilled into the Kennebec River during renovations on a local sewer station last month.

A barge struck and punctured the pipe Oct. 22, spilling an estimated 150,000 gallons of raw sewage into the Kennebec River, according to Winslow Public Works director Paul Fongemie.

Construction workers were in the final stages of replacing the single pipe beneath the Kennebec, through which all of Winslow’s untreated sewage from the Chaffee Brook Pump Station is pumped to Waterville’s Kennebec Sanitary Treatment District.

“They hit our existing force main with a barge and punched a hole in it. It took us about 29 hours to get divers in there to fix it,” Fongemie said. “We lost 150,000 gallons of sewage to the river.”

The pumping station was built in 1970 and until a $9 million project to modernize the facility began last November, it had not been updated since 1998. Repair work has faced repeated delays and budget increases due to flooding and federal permitting processes.

While “it was not a complete break in the pipe,” according to Maine Department of Environmental Protection Deputy Commissioner David Madore, sewage flowed into the Kennebec for about 30 hours before underwater divers could be found to repair it.

Divers patched the hole within two hours, Madore said. There is no plan to remediate the sewage spilled into the Kennebec.

“This was a rapid and appropriate response,” Madore wrote in an email. “Unfortunately, with this type of break there is no ‘cleanup’ that is feasible in terms of recovering any sewage that was discharged to the river.”

Because the pipe had only partly ruptured, the Chaffee Brook station was able to continue operating at near full capacity throughout the ordeal, Fongemie said.

“We kept pumping (sewage) because we were still getting probably 90% across the river, so most of it was still going to the plant,” Fongemie said.

Low water levels in the Kennebec River likely caused the barge to strike the pipe, which lies at the bottom of the riverbed, both Fongemie and Madore said.

“Last year was no problem; we had 6 feet of water. This year we got 2 feet of water. It happens,” Fongemie said. “It was handled as quickly as possible.”

It was not immediately clear if any action would be taken against Winslow Public Works or the contractor operating the barge that struck the pipe.

The DEP is still reviewing the case, though, Madore said, “it is noted that the cause was accidental during a challenging project to upgrade important infrastructure and the response was very quick.”

Each year the Chaffee Brook station experiences three or four “overflow events” in which up to 300,000 gallons of sewage can spill into the Kennebec during flooding or high rainfall. The repairs to the station are intended to stem the frequency of such incidents.

There have been three major overflow events at the Chafee Brook station in the last three years, the DEP says.

Operator error sent more than 50,000 gallons of sewage into the Kennebec in a March overflow event this year. Another 4,000 gallons were discharged during a 2022 wind storm. An “unknown quantity” of sewage entered the Kennebec when the Chaffee Brook station was flooded with 12 feet of water in December 2023.

Prior to the passage Clean Water Act in 1972, the Chaffee Brook station pumped sewage directly into the Kennebec River. The station’s last upgrades in 1998 were made after about 100,000 gallons of sewage leaked into the Kennebec that year.

While officials had initially hoped to complete the upgrades by this summer, flooding and federal permitting processes have extended work at Chaffee Brook through 2025.