Siler City, NC — Wastewater Treatment Plant Improvements

The Siler City Wastewater Treatment Plant Improvements project is a comprehensive, multi-phase upgrade designed to increase treatment capacity, improve plant performance, and support long-term regulatory compliance for the growing Siler City community. The project expands the facility’s capacity to 6.0 MGD and enhances biological treatment processes to meet National Pollutant Discharge Elimination System (NPDES) permit requirements.

Major improvements include:

• New headworks facility with advanced screening and grit removal systems
• New influent pump station
• New biological treatment system using the BIO-DENIPHO process 
• Conversion of existing oxidation ditches to BIO-DENIPHO configuration
• Tertiary disc filtration
• Ultraviolet disinfection and post-aeration systems
• Upgraded sludge dewatering facilities
• Rehabilitation of existing secondary clarifiers and construction of a new clarifier
• New return activated sludge and waste activated sludge pumping systems
• New piping, electrical systems, instrumentation, controls, and telemetry

A key challenge involved maintaining continuous treatment operations within the active facility while major upgrades were underway. To support interim performance, the team temporarily converted an existing oxidation ditch to a multistage biological nutrient removal process while new systems were constructed. This required careful sequencing, coordination with plant operations, and attention to seasonal treatment requirements.

Advanced modeling and coordination tools helped the team manage complex site conditions, resolve conflicts, and adapt to evolving design requirements. Upon completion, the improved facility will provide Siler City with more reliable, efficient, and resilient wastewater treatment infrastructure designed to support future growth and long-term environmental performance.