New London ― A series of unexpected ruptures along a major sewer line on Pequot Avenue late last year that led to sewage backups will cost nearly $2 million to fix.

That repair job is expected to be followed by the reconsideration of a defunct city sump pump replacement program aimed at preventing future overflow incidents.

The City Council this week unanimously authorized appropriating up to $1.8 million to conduct an emergency repair of the sewer line running between Jerome Road and Neptune Avenue not far from Ocean Beach Park.

About half of the funding will cover the cost of introducing about 3,500 linear feet of flexible lining into the damaged 12-inch diameter pipe. That lining will cure into an inner shell ― harder than the pipe it protects ― after exposure to an ultraviolet light system, Public Utilities Director Joseph Lanzafame said on Thursday.

The work will be done by the National Water Cleaning Main Company which submitted the lowest, $1.09 million, of the three bids for the project.

The remaining funds are needed to cover excavation, paving, labor and project management costs, according to Feb. 20 memo from Lanzafame to Mayor Michael Passero.

The problem began in mid-December when officials learned the sewer line, which ferries wastewater from the Ocean Beach pump station and another on Pequot Avenue, ruptured. Two more fractures occurred within a three-week span, Lanzafame said.

A temporary bypass was placed along the street to allow for the inspection of the damaged line, but that pipe was overwhelmed by heavy January rains leading to sewage backing up into 10 residences – including five beach bathroom structures – on Pequot and Mott avenues and Lower Boulevard.

A more robust bypass pipe was added on Jan. 12 and is still in place.

Lanzafame said the January backup can be partially attributed to home sump pumps being illegally hooked into the city sewer lines, which are not designed to handle stormwater flow.

“We will be discussing resurrecting an old sump pump replacement program we introduced years ago,” he said. “There’s nothing nefarious about those hook-ups; people just don’t know not to connect to a sewer line. But it’s a significant cost increase to treat all that extra flow.”

Lanzafame said it was initially thought that scouring action due to grit and sand whirling through the flow may have caused the original main line rupture, but that theory was discarded after a close inspection of the pipe.

“It’s hard to say or know what caused the issue,” he said. “But the bottom of that pipe had degraded to the point where it was paper-thin.”

The council on Monday approved transferring the repair funding from the Water and Water Pollution Control Authority’s general fund account, which stood at $6.2 million as of this week, Finance Director David McBride said.

The lining, a specialized material only manufactured in Germany, is slated to be delivered in about five weeks. Installation will take another two to three weeks and paving several more weeks.

Lanzafame said his hope is to get the pipe repair job done and the partially above-ground bypass pipe removed before early May when the area is inundated with beach tourists.

“It would take more than a couple of cones to protect that length of pipe when you have so many people coming in that are unfamiliar with the area,” he said.

Though the liner material does not come with a warranty, Lanzafame said the repaired pipe is expected to remain intact “beyond 50 years.”

j.penney@theday.com