City of Atlanta Water Supply Project
City of Atlanta Water Supply Project
City of Atlanta Water Supply Project | Atlanta, GA
The City of Atlanta has embarked on an ambitious project to correct aging conveyance infrastructure and critical lack of raw water storage capacity that threaten the ability to provide a reliable drinking water supply to its citizens.
The current raw water supply system managed by the Department of Watershed Management (DWM) for the City of Atlanta consists of aged operating components. Cast iron conveyance mains of diameters 30 inches, 36 inches, and 48 inches were installed in 1893, 1908, and 1924 respectively. Although these were renewed with a cement liner in the 1950s, they have far exceeded their design life. A fourth line, a 72-inch steel main, was built in 1975 and metallurgical weaknesses restrict its operation to warm weather months. In addition, the City has only one functional raw water storage reservoir at its largest water treatment plant, providing only several days of capacity.
The Chattahoochee River is the source of raw water for the entire Metro Atlanta. The path of the new conveyance system will follow closely the path of the current cast iron lines. The new five-mile conveyance will end at a quarry site that will be transformed into a new water storage facility. The City acquired the Bellwood Quarry in 2006 to create a raw water storage facility to improve the reliability of their water supply system and to move raw water from the Chattahoochee River to two water treatment plants and storage facilities. It will be designed to meet the current withdrawal permit limits and store any excess water not used for daily drinking water. Once filled, this facility will hold 2.4 billion gallons of water to provide the City a 30-day backup water supply.
The project will address the objectives of achieving 100 years of asset lifecycle and flexibility in system operations. The estimated cost of the conveyance and water storage is approximately $280M, and will include the following main components:
- Conversion of the Bellwood Quarry into a 2.4 billion gallon water storage facility.
- Construction of a 5-mile long, 10-foot diameter tunnel to connect the new water storage facility, Hemphill WTP, Chattahoochee WTP and the Chattahoochee River intake.
- Installation of pump stations (estimated at 145MGD capacity) and associated vertical shafts, flow control devices, and instrumentation and control systems.
Project Cost: $270M
Owner: City of Atlanta
Construction of the program is being accomplished under one contract using the Construction Manager at Risk (CMAR) process, and is currently scheduled to extend through September 2018.
Under subcontract to MWH Americas, CAS provides Construction Management expertise to the MWH Owner’s Representative Team to define and protect the Owner’s interests; act as the primary line of defense against risks to the project budget and schedule; provide advice unencumbered by any interests or firm affiliation other than those of the Owner and the Project; maximize the Owner’s control over the project’s scope, quality, time, and cost; and prepare accurate unbiased reporting of progress, and details pertaining to project issues as they arise and are solved. During the current preconstruction phase, CAS duties include analysis of GMP submittals/proposals, validation of CMAR and engineer-of-record cost estimates and value engineering proposals, provide constructibility review, and provide general oversight of the CMAR and engineer-of-record to ensure they perform their work in accordance with City expectations and requirements.