WESTFIELD – The Water Commission voted last night to award the contract for repair of the Granville Reservoir dam and spillway to a Weymouth construction company.
Water Resource Superintendent Dave Billips said that the staff recommendation was to award the contract to Northern Construction Services, LLC, which submitted the second lowest bid, $2,990,000 for the project. The lower bidder, Roach Brothers Construction, Inc., was allowed to withdraw their bid because of an error.
The City Council recently approved a $3.75 million bond to finance repairs to the Granville dam and spillway. The Granville Reservoir provides about half of the city’s drinking water supply.
Billips said last night that the actual contract documents were not available to the commission for their signature because they were being signed by the contractor to hasten the project which is already behind the projected schedule.
“We’re a couple of months behind on this project because we ran into snags in the permitting process with the DEP (Department of Environmental Protection) and the state dam regulators,” Billips said recently. “But that is not unusual whenever you’re doing work on a dam.”
The timing of the project is critical because the reservoir was taken off line in early spring when work started on replacing the raw water main that transports reservoir surface water to the city’s treatment plant in Southwick.
The department’s surface water supply is much cheaper than well water because it uses gravity to move the water to the treatment plant, then to elevated storage tanks which pressurize the system.
The department is now relying on well water to provide domestic water service to city residents, an expensive alternative because of the huge consumption of electricity to pull the water out of the aquifer, and then pump it up to the storage tanks.
Typically the city’s water is divided equally between the two systems. The current improvements to the raw water transmission main will increase flow from the reservoir to the treatment plant by 1 to 1.5 million gallons a day.
The commission also approved an outdoor water-use ban when the reservoir was taken off line in the middle of April for both the dam repair and transmission main projects.
The dam repair work includes reconstruction of a section of the reservoir overflow channel which was washed out during Tropical Storm Irene, and repairs of damage to the dam face that have occurred since the structure was originally constructed in 1928.
Billips said that the city will receive an $800,000 reimbursement for the Irene related spillway damage from the Federal Emergency Management Agency and the Massachusetts Emergency Management agency after the replacement work is complete.
The engineering cost projection for the spillway repair is $2.1 million, but the project will also include an estimated $1.1 million in repairs to the face of the reservoir dam.
Pushing the “toe” or base of the dam out 30 feet, creating a more gradual slope, will protect the dam face. The original dam, built in 1928, was constructed with “weeping tiles” under the top layer of soil, a system to wick water off the dam face. However, over the years, the dam face has been damaged and a new drainage system will be installed to remediate existing, as well as preventing future, damage to the earthen dam.
