Sequoia was awarded the contract to excavate four former CCR basins, two coal pile runoff ponds and an ash stack area so that the land can be redeveloped for a future power generation unit. The 90-acre project includes dewatering the existing basins, confirming clean closure by visual inspection and achieving closure grades and then backfilling all ponds to match surrounding grades. All materials excavated from the site were hauled to a private, third part municipal solid waste landfill.
Sequoia removed 620,00 cubic yards of ash and impacted soil material and hauled them 25 miles to a MSW landfill operated by a private waste company. Once the ponds were cleaned, over 700,000 cubic yards of new soils were imported to backfill the excavated areas to match surrounding grades. The imported fill was compacted to 95% standard proctor to support future re-development of the former coal generating plant area with a new generating unit. Provisions for addressing buried asbestos throughout the site we in place throughout the project. If suspect material was identified, the area was cordoned off, the material tested for the presence of asbestos and then abated in accordance with site specific asbestos abatement permit requirements. Over 2,000 tons of legacy construction and demolition materials were removed from the site including loose materials in the basins as well as legacy pump stations, concrete support and pipeline structures as well as modifications to and existing flow control discharge weir upon project completing. Close coordination was required to avoid impacting a major natural gas pipeline that transected the site and avoiding multiple low hanging electrical transmission lines over the basins. Sequoia designed, constructed and operated a water filtration system to meet State NPDES discharge limits for water quality discharges. The project is allowed a 24-month duration to meet State and Federal ash basin closure deadlines.
