City of Statesville, NC
Third Creek Wastewater Treatment Plant Upgrade and Expansion
McGill assisted the City of Statesville with the planning, permitting, design, and construction administration of the Third Creek Wastewater Treatment Plant (WWTP) upgrade and expansion. The project involved an upgrade and expansion to 6 MGD with biological nutrient removal (BNR) treatment.
Major project components included:
- Two mechanical screens
- Influent pump station with four pumps
- Vortex grit removal
- Two BNR treatment trains
- Two secondary clarifiers
- Chlorine contact structure with chlorine addition, chlorine contact, non-potable water pumping, effluent metering, dechlorination, post-aeration, and effluent sampling
- A return sludge pump station with three pumps
- Sludge wasting
- Aerobic digester upgrades
- Plant sewers, piping, valves, electrical, standby generator, controls, SCADA, and related appurtenances
Statesville desired to pursue a plant expansion to accommodate future population growth and increased wastewater flows. The facility was also facing low-nutrient limits, due to the impairment of High Rock Lake, downstream of the plant’s discharge outfall.
McGill assisted the City in obtaining a modified NPDES discharge permit for the facilities project with interim, less stringent effluent limits. A phased treatment strategy was implemented, which paralleled the NPDES permit negotiated with NCDEQ and EPA. A three-stage biological process was selected for the first phase nutrient removal, with anaerobic, anoxic, and aerobic stages. Influent wastewater enters the anaerobic basins and combines with return activated sludge (RAS) from the clarifiers without aeration to allow phosphorus-storing bacteria to excel. The oxidation ditches operate as aerobic basins with mechanical mixing and aeration, as well as variable frequency drives (VFDs) to maintain the dissolved oxygen (DO) at optimal levels. Mixed liquor internally recycles through the anoxic basins to denitrify oxidized nitrogen components (nitrate and nitrite) formed in the aerobic process. The facility was also designed to accommodate a future upgrade to a 5-stage BNR process, chemical addition, and filters to meet the lower-nutrient limits.
McGill assisted the City with procuring low-interest funding through the Clean Water State Revolving Fund in the amount of $23 million. The project bid in 2013 for $2 million under the project budget. The project was successfully completed and the plant began operating in August 2015.
“McGill provided a high level of service during the complex permitting process. The City’s interest was well looked after and they communicated well with stakeholders. Their continuous pursuit of funding on the City’s behalf went above and beyond the traditional role of consultants. There was continuous and seamless progression until successful completion of the project.”