LEWISTON – A cost-saving plan to build giant underground tanks to hold heavy storm runoff will go ahead, councilors agreed Tuesday.

Councilors approved the purchase of two parcels of land between Lincoln Street and the Androscoggin River for $750,000. That includes 15 Lincoln St., home to Schemengee’s Billiards and Infab Refractories. The second lot, at 34 Water St., is vacant.

The building will be torn down to let crews work on an underground stormwater line there. The city plans to install a series of five 350-foot-long concrete culverts underground on the Water Street parcel.

Downtown storm drains would flow into the tanks during heavy storms. That water would be pumped back through the treatment plant once the storm had passed and the runoff had subsided.

The project will cost $5 million, compared to the $21 million for a combined sewer overflow project. The overflow project would involve digging up most of the downtown streets over the next several years.

Preliminary work should begin this fall and wrap up next summer – just in time to meet a federal storm-sewer separation deadline, according to Lincoln Jeffers, assistant to the city administrator.

The city is negotiating with both Schemengee’s and Infab to find new locations, Jeffers said.

Combined sewer overflow systems link storm drains with sanitary sewers from homes and businesses. The street runoff can overwhelm the treatment plant during heavy storms, and that forces a combination of stormwater and sewage into the river.

Lewiston has spent $12.1 million since 1997 on sewer overflow projects, installing about 58,000 feet of sewer drains. Those projects, part of a 15-year program to meet federal water quality standards, involved digging up streets to build a duplicate drainage system for rain and snow runoff.