WASTEWATER/City performs pipe repairs without digging
Newton, Mass., has started a pipe rehabilitation project to repair some of its oldest sewers. But, because it wants to avoid major disruptions on roads, the city is attempting the repairs without digging up any existing pipe.
Installed more than 100 years ago, Newton’s original egg-shaped, brick sewers were constructed to divert groundwater from the sanitary sewer flow. However, deterioration of those pipes has allowed groundwater to infiltrate the sanitary system, increasing the amount of sewage that must be transported and treated by the Massachusetts Water Resources Authority (MWRA). The problem was costing the city significantly more in sewer fees — totaling $14 million annually — according to Utilities Director Jay Fink. He expects charges to drop 5 to 10 percent after the rehabilitation is completed.
Located near Boston and bordered on three sides by the Charles River, Newton began looking for rehabilitation options two years ago. The city contracted with Insituform, Chesterfield, Mo., to repair 51/2 miles of damaged sewers using a cured-in-place technology that restores the pipes without digging. Workers enter the pipeline from manholes and use water pressure to insert a flexible liner into existing sewers. The liner is then heated and cured in place to form a “pipe within a pipe.”
The city is performing installations in segments across two-thirds of the city with nearly 30,000 feet of pipe; each installation requires 12 to 36 hours to complete. During the rehabilitation, a temporary bypass pumping system transports sewage, which does cause some inconvenience for the residents near the temporary bypass, Fink explains.
As part of the project, the city also is rehabilitating manholes and access ports — the connections between the underdrains, the sanitary system and the stormwater system. A public outreach program, accomplished through the media and door-to-door visits, has informed residents about the work and explained how it would affect them.
Residents adjacent to a work area may experience a slight water shortage for 15 to 24 hours, Fink says. When the work near their homes is completed, the residents are informed before workers move to the next site. “It’s very important to have a good public notification system before undertaking this kind of project,” Fink says.
Newton received state and federal funding to finance the $4.2 million project, which began in November. It is expected to be completed in May. A second phase, covering cleanup work and additional rehabilitation, will start later this year and will require about nine months of work.