South Fulton County Wastewater Capacity Study

The nine cities in the southern part of Fulton County are experiencing rapid growth. To prepare the sanitary sewer system to meet the needs of each city through a planning horizon of 2050, the County commissioned Gresham Smith to determine the current capacity of the collection system, pumping and treatment facilities and develop a road map for future expansion. Ultimately, we delivered a comprehensive capacity evaluation report with recommendations for improvements and the associated costs.

To determine total flow projections for the planning decades between 2020-2050, our team coordinated with each of the nine municipalities to develop individual flow projections based on local conditions. We paid special attention to interjurisdictional flow meters and existing cross flows to prevent double counting or capturing flows not counted by billing meters. After compiling the data, our team updated and calibrated the County’s InfoWorks ICM model.

For each planning decade, we evaluated the system’s pump stations, force mains and gravity sewers to determine if upsizing would be needed. We identified the need for more than 120,0000 linear feet of new gravity sewer and more than 34,000 linear feet of replacement sewer, as well as eight new pump stations, three upsized pump stations and more than 92,000 linear feet of force main. We then estimated the costs associated with each upgrade. As a follow-on effort, we prepared a water/wastewater rate analysis to identify a rate structure that will support the improvements to south Fulton County’s sanitary sewer system.