Date
Monday, September 9, 2024
Time
2:00 PM - 2:30 PM
Location Name
M112
Name
Calls Creek WWTF Design Build Project
Track
Engineering & Construction
Description

The Oconee County Board of Commissioners, Georgia, selected the Ardurra/Crowder Construction Design/Build (DB) Team to upgrade and expand its existing 0.67 million gallons per day (mgd) Calls Creek Wastewater Treatment Facility. The County’s existing facility consisted of an oxidation ditch that was followed by a membrane bioreactor process. The County had an approved design concept for upgrading and expanding the facility to have a maximum monthly design flow capacity of 1.0 mgd that had been approved by the Georgia EPD. However, the County decided to complete the project using the progressive design/build process with the expectation that they could solicit best-value, alternative design concepts that would better meet the overall goals and objectives for the upgrade and expansion of the WWTF. Our Design/build approach for the project included soliciting input from the County’s management, engineering, and operations staff throughout the project by using multiple workshops, milestone design meetings, and specific design/construction meetings to gain their endorsement of the proposed methods for developing optimal solutions to the project issues. This approach ensured that construction expertise was involved throughout the design and design expertise was involved during construction. Value engineering was used throughout the design phase. This began at inception during the selection of materials, plant equipment, and process equipment. Using this workshop approach, we developed a Maintenance of Plant Operations (MOPO) Plan to ensure continued operation of the existing facilities during the design process. No specific process issues were experienced because we held weekly meetings with plant personnel to coordinate upcoming work and deliveries so that the existing facilities remained accessible throughout the project. Existing pipe and utility lines were located before any connections or crossovers to ensure the exact locations were known. Ardurra used our “in-house” Excel desktop wastewater biological process model to develop conceptual value-added alternatives to upgrade and expand the facility and reviewed these live with the County personnel. We evaluated multiple “what if” scenarios during a specific workshop and refined the number of alternative processes to determine the “best value alternative”. We used this model to quickly develop, evaluate, and optimize multiple alternative treatment scenarios and technologies and their associated costs. Following this workshop, we further evaluated the selected alternative using the EnviroSim BioWin Wastewater Process Simulation Software. The alternative that was selected by the County included constructing a new 1.5 mgd treatment plant with biological nutrient removal (BNR) capacity and tertiary filters to meet the new limits for total phosphorus that were imposed as a result of expanding the facility. Our design approach also facilitated the easy expansion of the facilities to 3 mgd in the future and maximized using the existing oxidation ditch basin for biosolids storage.