LEWISTON - A collapsed sewer pipe and not a mysterious blob is to blame for a Main Street blockage, according to city officials.

Crews from St. Laurent and Sons pulled the first 20 feet of 12-inch diameter non-reinforced concrete from under the intersection at Bates and Main streets Tuesday afternoon. It's part of project that should continue throughout the week.

"The end result is that we didn't collapse the pipe trying to clear a blockage," said Kevin Gagne, deputy city public services director. "The back up was there, and it was caused by a collapse."

Crews discovered the clog earlier this month, identifying it as a white, doughy blob blocking about 50 feet of pipe. Gagne said all attempts to dislodge the clog failed. Gagne said he wasn't sure if that work had caused the pipe to collapse in places.

The 170-foot-long sewer pipe on Main Street starts between Blake and Bates streets and continues south. Six businesses feed into the line above the blockage: Wolf Eye Associates, the United Baptist Church, Sam's Italian Foods, Classy Lady Boutique, PEG Associates and Pro-Print.

Gagne said the pipe is actually collapsed in several places along its length.

Crews found pockets of dirt-free voids around the pipe in places. Those come from leaks in the pipe farther upstream washing the dirt away. That weakens the pipe and can lead to a complete collapse.

"That's when it starts," he said. Sewage begins backing up the around the break.

"We know we have more voids, further up along the line," he said. "So it's likely we'll find more collapses as we go along."

The work is costing $51,000, Gagne said. The city has the option of paying an additional $12,600 to have St. Laurent and Sons return in the spring to prepare the street for final paving.