An American Electric Power plant in Ohio generates electricity from two, 1,300-MW, coal-fired units. The client's objective for the project was to have additional capacity for residual waste disposal available at a reasonable construction cost before the existing coal ash residual waste landfill (RWL) reached capacity in approximately 18 months.
Geosyntec’s Scope of Services
Geosyntec produced a value engineering assessment that examined a greenfield site and two variations of lateral expansion. One involved modifications to the preliminary lateral expansion approach, and the other involved a hybrid lateral and vertical expansion at the existing landfill. Further, we examined the overall financial effect of using the expansion site as a cover over the existing fly ash impoundment. The client selected the hybrid lateral and vertical expansion approach.
Geosyntec then performed detailed engineering and design of the selected landfill expansion option and prepared the permit-to-install (PTI) applications for submittal to the Ohio Environmental Protection Agency (OEPA). Our comprehensive subsurface site investigation program, in accordance with OEPA requirements, yielded the geologic, hydrogeologic, and geotechnical data necessary for the siting and design of the landfill. Sampling and analysis of fly ash and an assessment of static and seismic liquefaction were incorporated into the investigation and design. We finalized the engineering analyses, detailed design drawings, and supporting plans and report for the permit application. The permit application included 67 drawing sheets addressing the siting criteria, subsurface characterization, staged site development sequence, detailed landfill grading and design sheets for the liner, leachate management, stormwater management, air, and final cover systems and closure plan of the landfill expansion. Construction documents were prepared in 2013.
Geosyntec addressed significant geometric constraints and geotechnical challenges to achieve an acceptable disposal capacity for the expansion. We worked with the client during the leachate and stormwater management system design to utilize existing leachate/stormwater treatment ponds, thereby reducing the number of additional future point discharge permits required for the facility. The client reported that the estimated initial startup cost was one of their lowest over the past 10 years. OEPA verbal approval of the PTI was received only 14 months after initial submittal, which is four months faster than typical permit approval.