as the Final BART Rule; The agreement contains a commitment by the current owners of NGS to cease their operation of conventional coal-fired generation at NGS no later than December 22, 2044. Wastewater handling NGS was built with one of the first zero liquid discharge (ZLD) systems in a power plant, recovering all cooling tower blow-down and runoff from developed areas of the site. The waste water is processed through three brine concentrators and a crystallizer, which remove the solids and produce distilled water for re-use within the plant. Several lined ponds are used in conjunction with the ZLD system to capture and regulate the flow of waste water to the system. Byproducts handling The plant sold about 500,000 tons of fly ash per year for use in the manufacture of concrete and Flexcrete insulating block building product. Bottom ash and gypsum, a byproduct of the scrubber operation, are dewatered in the removal process; and, along with any fly ash not sold, were landfilled on-site as solids. The plant's ash handling contract required the landfilled ash be covered with a minimum of two feet of native soil cover at closure, and be contoured to contain a 100-year storm runoff event to prevent erosion, although the original lease had only specified covering it with six inches of native soil. Economic aspects Economic benefits of the plant resulted from NGS wages and site leases, as well as Kayenta Mine wages and royalties that result from NGS coal purchases, NGS being the sole source of revenue for the mine. The plant and mine annually pay out about $100 million in direct wages and $50 million in leases and royalties. The majority owners of the NGS did not plan to keep the plant running past 2019, because natural-gas fired electricity is a cheaper nationwide trend. The Navajo Nation has petitioned the federal government to keep the plant open and preserve Navajo jobs. This would likely require relaxation of emissions standards and/or direct subsidy. Plant employment, leases, and payments NGS had 538 employees, and paid about $52 million per year in total wages. The 1,786 acres for the plant site is leased from the Navajo Nation. Rights-of-way and easements on tribal lands, permitted under a 25 U.S.C. §323 grant, include the plant site, 78 miles of railroad right-of-way covering 1,309 acres, and 96 miles of transmission line right-of-way covering 3,850 acres. Annual lease payments to