Sewer Consultants Recommend Repair Priorities
By Kevin Rudden Staff Reporter/Columnist · June 19, 2012
The Sewer Department's consulting engineers have begun prioritizing the $3.5 million in repairs to the town's sewage system they outlined to the Board of Sewer Commissioners in a Comprehensive Wastewater Management Plan (CWMP) first presented in April.
Questioned by board members at their May 22 meeting, consulting engineers Tata & Howard, Inc. of Marlborough recommended as its two top priorities the need to replace a temporary pump helping to bring sewage into the wastewater treatment plant with a permanent one and building a sludge storage/pumping facility at the plant. A third priority discussed was rebuilding the Field Pond sewage pumping station.
Overall, the CWMP said the plant needs about $1-million in preventive maintenance – including that new pump – to prolong its life by another two decades and said that sewage systems pumping stations located throughout the town need about $1.7 million in upgrades and maintenance. The sludge storage/pumping station would cost an additional $750,000.
Jack O'Connell, senior vice president at the engineering firm, said the sludge storage/pumping facility should be considered a priority because it would pay for itself within a few years. The sludge – basically the solid material left over after treating sewage – used to be placed in an adjacent landfill until that reached capacity, O'Connell explained in April. The Sewer Department now stores it in various sections of the treatment plant and pays to have it trucked away, he said. By installing equipment to reduce the water content in the sludge by half – from six percent to three percent – the Sewer Department will save enough money on hauling costs to pay for the storage/pumping station, O'Connell said.
The commission also looked at Tata & Howard's initial recommendations for continuing to remove groundwater inflow and infiltration ("I and I") from the sewer system. Project Engineer Amanda Cavaliere said the Sewer Department in 2008 and 2009 concentrated on the three worst areas of town by relining sewer mains with a cured-in-place pipe (CIPP) process. CIPP is a technique that does not involve digging up streets. Instead, a jointless flexible liner is placed inside a sewer main, "cured" in place, and then forms a seamless "pipe within a pipe" that prevents groundwater from entering the sewer main.
For the fiscal year beginning on July 1, the town should look at six more areas, replacing old sewer pipes where needed and using the CIPP process for pipes with cracks in them, Cavaliere said. Her firm will look at the list of work that needs to be done and recommend a priority list, she added.
The developer of the Walden Woods condominium complex off Cedar St. (Route 85) will do the pipe replacement work as its part of the process that allowed sewer mains to be extended to that condo development, Sewer Superintendent John Mainini said.