The JEA St. Johns River Power Park is a 1,260-MW coal and petroleum coke fired power plant located in Jacksonville, Florida. Coal combustion products (CCPs) generated at the facility are disposed in an on-site CCP landfills. Stormwater (also referred to as “contact water”) from the Area II CCP Landfill discharged to a single retention pond where suspended CCPs were allowed to settle before the contact water was pumped to the facility’s industrial wastewater treatment system. As part of the Area II CCP Landfill Final Closure, the Florida Department of Environmental Protection (FDEP) required that JEA clean close the retention pond and provide documentation that all CCPs had been removed from the pond.
Geosyntec’s Scope of Services
Geosyntec was retained to prepare the final closure plan for the 37-acre Area II CCP Landfill, which included the assessment and remediation of the Area II CCP Landfill’s retention pond. To minimize the potential for false positives caused by traditional analytical techniques and reduce costs by accelerating the project schedule, Geosyntec pioneered a field verification method for identifying CCPs. The new method allows for the real-time assessment of any heavy metals in the retention pond.
Following excavation of the visible CCPs using traditional methods, the initial step of the field CCP verification method started with the collection, drying, and visual inspection of dozens of soil samples utilizing a 7X hand lens. Visual characteristics such as color, texture, lustrousness, and fracture were noted and compared to end member samples (i.e. site specific standards) of native soils, site specific CCPs, and uncombusted materials. If no CCPs were noted, a subset of the samples collected was subjected to the second field verification step. The second field verification step utilized a polarized 40X to 600X petrographic microscope to further assess the CCP removal efforts. The sample was again compared to end member samples. If CCPs were noted the excavation continued; however, if no CCPs were identified during the second tier observation, then a subset of the samples was submitted to a laboratory for verification analysis using polarized light microscopy (PLM) and scanning electron with energy dispersive X-ray spectroscopy (SEM/EDS) using the Methods for Evaluating Application of the Coal Ash and Wood Ash Exemption Under the Massachusetts Contingency Plan.
Geosyntec’s trained staff oversaw the successful removal of more than 11,000 tons of CCPs. They also were able to positively differentiate CCPs/uncombusted materials and native soils and to confirm their findings by laboratory microscopy analysis. This project demonstrated that this field CCP verification methodology can be used as a real-time method to dictate the terminal depth of CCPs excavations and assess the extent of CCP impacts. Without this method, tons of additional material may have been removed unnecessarily.