MIDDLETON — The beeping front end loaders and busy construction crews at the Danvers water treatment plant on Lake Street are out of sight to most Danvers and Middleton residents.
But the importance of the project along the shore of Middleton Pond will be evident every time customers in both towns turn on their taps.
A more than $20 million project to retrofit the Vernon C. Russell Water Treatment Plant is now 80 to 90 percent complete, and it’s expected to wrap up this fall, said Richard Rodgers, the town engineer for Danvers. Danvers supplies both towns with water, mostly drawn from Middleton Pond.
The upgrade is expected to give the plant another 20 to 30 years of life, and allow it to meet stringent new regulations in the federal Safe Drinking Water Act by 2015.
In the meantime, the work has caused discolored water in some areas, but new pumps should clear up the problem. The water is safe to drink, officials said, and residents can run cold water to flush out their pipes.
The soup-to-nuts renovation and addition involves everything from a new walkway at the front entrance to construction of new filtration, ozone treatment and sludge dewatering buildings. The original plant went online in 1976.
The plant also changed the way it disinfects water, switching from chlorine to monochloramines. The latter chemical lasts longer and causes fewer harmful byproducts.
The new filtration building at the back of the plant added massive sand and carbon filters, each the size of a large, rectangular swimming pool, to the two filters already in place. This work increased the plant’s capacity to pump out clean water at a higher rate.
The upgrade also includes a new sludge handling facility to capture water from leftover sediments. Because the plant is not connected to sewers, it must store sludge in lagoons at the back of the property before it is trucked to the South Essex Sewerage District for disposal. Capturing water from the sludge will mean fewer truck trips and less waste.