Seminole Electric Cooperative, Inc. (SECI), is one of the largest electric generation and transmission cooperatives in the United States. ECT supported SECI with an initial siting analysis and ultimately the environmental permitting/licensing of a new 1,050 megawatt (MW) (nominal) gas-fired, two-on-one, combined-cycle generating facility at its existing Seminole Generating Station (SGS) in Putnam County, Florida. SECI intends to remove from service one of the two existing SGS 650 MW, coal-fired generating units.
ECT’s project efforts included baseline field surveys such as jurisdictional wetlands delineations, threatened and endangered species surveys, ambient noise monitoring, and background water quality data studies; impact analyses; and various modeling. These efforts supported preparation of a site certification application (SCA) for the project under the Florida Electrical Power Plant Siting Act, as well as federally delegated Prevention of Significant Deterioration (PSD) and National Pollutant Discharge Elimination System (NPDES) permit applications. ECT also prepared a detailed environmental assessment (EA) for the U.S. Department of Agriculture Rural Utilities Service (RUS) to support RUS financing assistance for the project under the National Environmental Policy Act (NEPA).
For PSD permitting efforts, ECT conducted air emissions netting analyses for the new facility coupled with removal from service of an existing coal-fired generating unit. The netting analyses showed the project would have a net emissions decrease for all pollutants except volatile organic compounds (VOCs), for which the net emissions increase was greater than the PSD significant emissions rate. Thus, only VOCs were subject to PSD review and required installation of an oxidation catalyst as best available control technology.
ECT’s NPDES permitting efforts included mixing zone modeling for cooling tower blowdown and wastewater discharges to the St. Johns River, as well as evaluations of aquatic organism impacts under Section 316(a) and (b) discharge and impact requirements. As part of the SCA, ECT conducted groundwater modeling to evaluate drawdown impacts on underlying aquifers due to groundwater withdrawals for process water uses and noise modeling to quantify impacts to residential receptors.
The RUS EA addressed site and other project alternatives, impact mitigation measures, human health and safety, and environmental justice concerns using U.S. Environmental Protection Agency’s SCREEN modeling tool. The EA also included the new 21mile natural gas pipeline to supply fuel, which would be permitted, constructed, and owned by others, as a related project.