PORTSMOUTH — Efforts to build a new Lawton Valley water treatment plant have produced an impressive rock peak that has risen in full view of West Main Road motorists.
It is only temporary though and is fated to be ground into pea stone and dust as the project progresses.
That mountain of rock is the result of the recent removal of an old 4 million gallon water tank that had been sunk into the Lawton Valley hillside.
The tank was installed back in the 1940s by the Navy which built the Lawton Valley reservoir and treatment system in part for Navy base water and firefighting needs, said William McGlinn, general manager and chief engineer of he Portsmouth Water and Fire District.The tank, which Mr. McGlinn said was set out of sight into the hill, was about 20 feet deep and measured about 150 by 150 feet.
“They had to jackhammer and blast to get it out,” he said, a task that involved digging into underlying rock ledge.
All that rock was delivered to a lower staging area and soon grew into a mountainous heap. It would have grown even bigger except that contractor C.H. Nickerson & Co brought in an array of rock crushers and heavy-duty loaders that have been working every day for weeks to pulverize the big rocks into pea stone size.
Some of that rock will go right back into the project, serving as a footing for the new water treatment plant’s foundation that will be poured before long.
“Rather than pay to have the rock removed and then pay to bring stone in, they are recycling what is there,” Mr. McGlinn said. If there is extra, it will probably be trucked away and sold for other projects.
In place of the old 4 million gallon in-ground tank, a new 1.75 million gallon hydropillar water tower will be built alongside the existing 2 million standpipe that sits atop the hill.
Although it will hold less water than the old tank, that water will be at a higher elevation — the lower section of the hydropillar is a steel support structure designed to hold the bulbous water tank aloft. The tower will be about the same height as the existing standpipe.
Not only will it benefit from the added pressure provided by that elevation, but the system will also be served by a new Lawton Valley water plant with much more “robust” pumps than the old one.
This is one phase of an ambitious Newport Water Department project to replace not only the Lawton Valley treatment plant but also water infrastructure in Newport. Paid for with an $85 million bond, the project will resolve long-standing water treatment issues and enable the system’s aging treatment system to meet today’s and future water quality standards. Water customers, including those served by the Portsmouth Water and Fire District, face rate hikes in coming years to pay for it all.
The project has a target completion date of late 2014.