WWTP NPDES Permitting Technical Support, River Surveys, and Water Quality Modeling
The City of Sumter was required to expand its wastewater discharge capacity in order to meet the needs of its growing community. Sumter’s Pocotaligo River Wastewater Treatment Plant (WWTP) discharges to the adjacent Pocotaligo River and the city sought to increase the WWTP’s wasteload allocation. HydroAnalysis provided NPDES permitting support, designed and conducted a river hydrologic and water quality field program spanning a two-year period, and developed and applied a river low-flow modeling application. HydroAnalysis conducted coordination meetings with state regulatory staff throughout the project to ensure approvability and compliance with water quality standards.
The river investigation was focused on determining the potential impact of wastewater treatment plant effluent on ambient dissolved oxygen concentrations in the river under low-flow summertime conditions. HydroAnalysis developed a quality assurance project plan and conducted a field investigation featuring long-term streamflow monitoring, dye studies, in-situ water quality measurements, and water quality grab sampling for laboratory analysis. The modeling analysis featured hydrologic and water quality simulation focused on critical summertime, low-flow, high-water temperature conditions.
The HydroAnalysis study found that the river had available assimilative capacity. As a result of our findings, the City of Sumter successfully obtained a revised NPDES permit that enabled the city to improve its wasteload allocation while maintaining water quality standards in the river. In September 2016, DHEC approved the Pocotaligo River water quality study and issued a new NPDES permit to the City of Sumter that will enable community growth for decades to come. HydroAnalysis received high praise for our river study and for our collaborative approach to working with the state regulatory agency.
This project was conducted for the City of Sumter, SC, under subcontract to Davis & Floyd, Florence, SC.