Photo courtesy Archer Western Construction LLC

“They had to keep the existing plant running while they built the new one adjacent to it,” said one judge. “In the water/wastewater world, that’s the toughest thing … You can’t turn the pipe off even for a minute.”

To manage that feat, the project team says everyone—contractor, engineer, owner and plant staff—worked together to develop work plans, which were staged to avoid affecting other plant operations essential to Cobb County’s water supply.

Photo courtesy Archer Western Construction LLC

The site was divided and existing facilities protected and buttressed during the demolition and construction. Leaving half of the plant in service meant designing a temporary control room to allow the owner to use a portion of the existing facility if demand for water required it during construction.

The safety record on the project impressed judges, too, with no lost-time accidents for the entire 353,000 man-hours and an incidence rate of 1.1, described by one judge as not the best in class, but right there with it.

Photo courtesy Archer Western Construction LLC

“It’s the open-heart surgery aspect of it,” that made it stand out, said one judge.

Subterranean pipe chambers and structures had to be constructed in variable materials from soil to rock, requiring special attention to excavation and backfilling to reduce the effect of different bearing materials. Concrete mixes were tailored to reduce shrinkage cracking, and included waterproofing admixtures to ensure water tanks remain watertight.

Project crews utilized 3D modeling, which Archer Western paired with site drawings to model all site yard piping and utilities to bring the entire project into one 3D model, used to identify conflicts well in advance of starting work.