August 2021
Archer Western completes new 33-MGD facility at Quarles Water Treatment Plant
Marietta, GA - Archer Western Construction has completed the replacement of Plant 1 at the James E. Quarles Water Treatment Plant in Cobb County. The Quarles plant treats raw water from the Chattahoochee River and distributes clean drinking water to the nearby communities. The project, orchestrated by the Cobb County-Marietta Water Authority, replaced the facility's Plant 1 with a new conventional water treatment plant capable of handling 33 million gallons per day (MGD).
The plant replacement project included the demolition of the nearly 70-year-old Plant 1, construction of a new facility, along with entirely new landscaping and the replacement of Plant 2's raw water meters. Associated site work included earthwork, electrical upgrades, yard piping and stormwater control that contributed to the overall improvement of the plant. A list of primary features within the newly constructed plant include:
• New raw water transmission main with flow meter and flow control valve.
• Three new hydraulic flocculation basins and three new sedimentation basins equipped with inclined plate settlers and hose-less sludge collectors.
• Eight new dual media filters with air scour backwash, including associated pipe gallery and filter building.
• New high service pump station with three 20 MGD horizontal split case pumps equipped with variable frequency drives.
• New alum bulk storage and concrete containment area and alum feed building.
• New approximate 460,000-gallon pre-stressed concrete backwash water storage tank.
A significant challenge for the project was managing demolition of the existing plant in order to allow the new plant to be built, while half of the existing plant was still in operation. The site was divided and existing facilities protected and reinforced during the demolition and construction. For half of the old plant to remain in partial service, a temporary control room was designed to house the existing control panels and computer workstations until the remaining half of the plant could be demolished.
"From demolition through construction, our entire team - Archer Western, Cobb County, Hazen and Sawyer, subcontractors and plant staff - worked together to develop and implement the project work plans," said David Walker, program manager at Archer Western. "This collaboration and teamwork was essential to properly demolishing the old plant, bringing the new plant online, testing its safety, and thereby ensuring delivery of high-quality water to the community."
The Archer Western team utilized 3D modeling to assist with the visualization and construction of the project. Archer Western engineers converted the 2D site drawings to create one 3D model of the facility. Structures were scanned and incorporated into the model to ensure the complex piping was fabricated correctly. With the use of this technology, Archer Western was able to identify possible conflicts and adapt to mitigate downtime during the construction process.
Archer Western crews self-performed construction of concrete structures, process piping, metal fabrications, and process equipment for this state-of-the-art facility. The project was completed under budget and with zero lost time incidents.
