Board mulls pipeline options
By DAN MORIARTY
Staff Writer
WESTFIELD – The Water Commission found itself between a rock and a hard place last night as it was asked to approve a project without sufficient data to make a deliberate decision.
The rock is the bedrock of the Granville Gorge, while the hard place is the extremely aggressive timetable to secure a $2.9 million, low-interest federal loan to install a new water pipeline between the Granville Reservoir and the water treatment plant in Southwick.
Dave Edson of Hoyle, Tanner Associates, Inc. said that pipe line is in need of replacement. The consultant has assessed the function of the pipe for more than a decade and observed a drop in the volume of water reaching the treatment facility.
“The (existing) pipeline is losing capacity, which has a real economic impact on the department because this is the least expensive water to produce because the system is almost entirely gravity fed,” Edson said.
Water Resource Superintendent Dave Billips said that the surface water collected in the Granville Reservoir accounts for about half of the city’s drinking water. The wells could produce more water if needed, but there is the cost associated with operating the wellhead pumps.
Edson said a 14-inch pipeline was originally installed through the Granville George in 1890, then two sections of 20-inch pipe were laid in 1927, above and below the pipeline in the gorge.
“When you have pipe that is over 100 years old, catastrophic failure is a concern,” Edson said. “The treatment plant has a (treatment) capacity of 2,800 gallons per minute while the pipeline has a capacity of 1,900 to 2,000 gallons per minute.”
Billips said the most efficient operation of the water treatment plant is at high capacity, which is not occurring because of the pipeline’s “limiting factor” in delivering water to the plant.
Edson said the federal low-interest loan, part of which is forgiven over time, is administered through a state revolving fund program, but that the engineering and design work needed to generate the cost of options in not funded through the loan, nor does the timetable give the city time for deliberate evaluation of those options.
The timetable requires the city to begin the design process, appropriate funding by June 30, and submit the loan application, with engineering, design and permitting documents in place, by Oct. 15, 2012, with a construction contract awarded by April 2013.
The project is also required to have a “green” energy element. The proposed option to meet that requirement is to install turbines inside the pipeline to take advantage of the “head” of water rushing down through the pipe from the reservoir. The power generated would be sufficient to operate the treatment plant, furthering reducing the cost of producing the city’s drinking water.
Edson outlined seven options, the benefits and potential costs of each option. One option is not to replace the pipeline, just release water from the reservoir down through the gorge and collect it as it spills out of the gorge, an approach that the treatment plant is not designed to handle.
“The treatment plant is designed to handle clean water from the reservoir and not water churned (with suspended particle) through the gorge,” Edson said.
The most expensive option is to drill a tunnel through the mountain from the reservoir to the area of Loomis Street.
Edson also described an option to pipe the water across the gorge and install a pipeline along Route 57, but the project then loses the green renewable energy element, because the system would rely on pumps and not gravity.
Digging up and replacing the existing pipeline is expensive, because that line is installed along a narrow path dug into the north face of the gorge. An alternative to that option is pipe bursting. In that alternative the pipe is destroyed and a new pipeline is pulled through the cavity left when the original line is burst.
Another alternative is to use the path to install a flexible pipeline down through the gorge. However that approach eliminates the ability to access the pipeline path with equipment needed for repair and, because it is above ground, make the pipeline vulnerable to vandalism.
Other factors included in the board’s discussion is that the city will retire the bond used to build the treatment facility in the next couple of year and the projected life of the plant is for another 25 to 40 years. But the treatment plant relies on the Granville Reservoir for water to treat and the pipeline to deliver that water.
Ron Cole, commission chairman, said the board needed more information to make a decision.
“We need to know the true costs of the entire project,” he said.
The Water Commission voted to continue the study of options to produce more definitive information it needs to make its decision.
Dan Moriarty can be reached at [email protected]
