Agenda - 06-01-2010 - 4k - Laserfiche WebLink

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Sarasota County, Florida 44 General Engineering and Environmental Management Services HDR has been assisting Sarasota County with its solid waste program since 2004 and has provided services for both the active Central County Solid Waste Disposal Complex (CCSWDC) and the closed Bee Ridge landfill. Key Elements: ■ 54- acre landfill expansion permitting/design ■ Landfill Master Gas Plan for 295 -acre landfill ■ Phase I LFGCCS design, permitting, and construction administration ■ Partial closure design (including solar cap), HDR prepared a permit permitting, and construction application, construction administration ■ Landfill gas utilization project documents, and served as design, permitting and Engineer of Record for an construction assistance ■ Borrow study x approximate 54 -acre expansion of the CCSWDC Class I landfill. The Phase II design incorporates several design and operational improvements over the previous Phase I design. These improvements were identified during a thorough review of the site history and during discussions with County staff and were presented in a Phase II Basis of Design Report as a precursor to the permitting effort. These improvements include provisions for potential future leachate recirculation and bioreactor operations, provisions for a potential future vertical expansion of up to 100 feet, increased airspace by removing sideslope benches, and minimization of the number of leachate transfer pumps required by designing all Phase II sumps to drain by gravity to a single pump station. The project also includes a 9,700 -foot leachate force main to an existing leachate storage tank. Due to the absence of suitable clay liner material in the vicinity of the landfill, Phase II incorporates a double synthetic liner system consisting of (from the top down) 2 feet of operational cover, a geonet composite drainage layer, a 60 -mil HDPE primary liner, a geonet composite leak detection layer, a 60- mil HDPE secondary liner, and a geosynthetic clay liner (GCL) placed over a prepared subgrade. In order to minimize the quantity of fill required for the low -lying site, an extensive field exploration was conducted to accurately identify historical high groundwater levels and to characterize foundation conditions including settlement parameters. The $18.5 project was well below the estimated construction cost and was completed five months ahead of schedule. Several landfill gas projects have been completed or are in progress for Sarasota County. HDR prepared a Landfill Master Gas Plan and Basis of Design Report that provides recommendations for the layout of landfill gas facilities for the entire 295 -acre Class I landfill. HDR has also provided assistance with reviewing and recommending a developer for a landfill gas utilization project for the Bee Ridge Landfill. Other services provided include preparing Title V Annual Operating Reports and Tier II sampling and testing at CCSWDC, and design and permitting of the Phase I landfill gas collection and control system (LFGCCS). HDR is currently providing construction administration services during the installation of the Phase I LFGCCS. HDR is currently designing and preparing permit documents for the partial closure of Phase I of the CCSWDC. The design includes a temporary final cover on the south slope of Phase I where it is anticipated that Phase III will be constructed in approximately 2020. The temporary final cover will consist of an exposed 60 -mil HDPE geomembrane that will enable Sarasota County to control landfill gas generation on the slope while reducing maintenance issues associated with a temporary soil cover. HDR also prepared a feasibility study for the potential use of flexible photovoltaic panels on the exposed geomembrane in order to generate electricity for sale to the local electric utility. The study indicated that Sarasota County could construct a 144 -kW SEC system on the 10 -acre south slope that will pay for the temporary closure and solar electric system and provide a net profit in electric sales over the life of the facility. The County is therefore including the solar electric system in the partial closure permit application. Page 29 1 L_