The Granville Reservoir remained dry as a safety inspection was performed last month. (File photo by Frederick Gore)
WESTFIELD – The weather pattern of cold Canadian air colliding with moist tropical air sweeping up the eastern half of the country has, and apparently will continue, to result on severe summer weather.
The cycle of storms is helping to fill the city’s Granville Reservoir after it was emptied during repairs to the earthen dam, dam spillway and raw water transmission line which carries reservoir water to the city’s surface water treatment plant in Southwick.
The Water Resource Department anticipated that Granville Reservoir would not have sufficient water to bring it and the treatment plant back on line until the fall, late September or October, and requested the Water Commission to extend its mandatory water ban on the outdoor use of water for a second year, a request that was approved at the beginning of this summer.
The constant pattern of days of rain may hasten the filling of the reservoir and allow the city to return the treatment plant to service. The raw water intake is 18 feet below the dam spillway and the intake is usually several feet below the surface of the reservoir to provide adequate pressure at the treatment plant
“It’s 40 and a half feet below the intake, so the level of the reservoir increased by eight feet since we closed the (outlet) valve last week,” Water Resource Engineer Charles Darling said. “We’ll see what the rain does (to raise the level) today. This will be good to fill the reservoir.”
The city has drawn water from aquifers since the treatment plant was closed, a much more expensive source of water because of the cost of electrical power to operate the pumps. Relying on the wells has also created problems in some areas of the city with water pressure.
The treatment plant feeding the Sackett water storage tank is at a higher elevation, which increases water pressure system wide.
The treatment plant also injects chlorine into the water distribution system which inhibits bacterial growth, particularly in long dead-end pipes where water tends to not steadily move, an environment conducive to bacteria growth.
The flow of water back into the impound area of the reservoir will create another problem, turbidity.
“The rains will wash a lot of sediment into the reservoir,” Darling said. “We’ll have to wait a couple of days to let that settle before we open the intake to the treatment plant.”
“Once we start getting water to the plant, we can begin the start-up process, testing everything, washing the filter beds,” Darling said. “It will be very good to have the plant back.
“If the summer stays wet it could happen sooner than we expected,” Darling said. “So maybe (the reservoir) fills more quickly than we expected. Usually we don’t get a lot of rain in July and the grass turns brown by the end of the month, but not this year.”
Granville Reservoir holds 600 million gallons of water and has increased the water level to about 18 feet below the top of the dam to operate the treatment plant which will take two to three weeks to be put back on line after the water starts to flow from the reservoir.
