The engineering, procurement, and construction of the plant were managed by Black & Veatch. It was expected that PG&E would pay approximately $1.5 million to Contra Costa County annually in property tax. The work for underground piping and powertrain equipment included loading, setting and alignment of heavy haul items, in addition to installation of pipe supports, piping, in-line instrumentation, platforms and enclosures. This portion of the work, along with associated management cost, encompassed 152,000 direct man-hours of labor over 21 months. By July 2008, construction was "two-thirds" finished. The gas turbines were first fired in November 2008; commercial operation, supplying power to nearly 400,000 customers, began on January 4, 2009. Randy Livingston, PG&E's vice president of power generation, said to the Brentwood Press that the project came "ahead of schedule, on budget, and we had no lost-time injuries during the entire construction of the plant". The overall cost of the plant was $386 million. Facility The combined-cycle facility is located at 3225 Wilbur Avenue in Antioch. While it was constructed as a nominally 530 MW facility, an additional 50 MW of low-cost peaking capability brings its overall capacity to 580 MW. The facility consists of a combustion turbine air inlet chiller system, two combustion turbines paired with heat recovery steam generators (HRSGs), one steam turbine, an air-cooled condenser system, generator step-up transformers, a plant substation, an interconnecting transmission line, an administration building, and a control building. The combustion turbine air inlet chiller system, made by Turbine Air Systems, uses aqueous ammonia to lower the temperature of air prior to being taken into the combustion turbines. While Mirant had originally intended to use evaporative cooling for intake chilling, PG&E switched to an air-cooled design due to a desire to avoid drawing water from the nearby San Joaquin River. The system is charged with up to 18,000 gallons of aqueous ammonia solution, or of ammonia; the ammonia storage tanks are in a walled containment basin. The combustion turbines were made by General Electric, with the model designation PG7241FA (the same as model designation 7FA.03, and the later re-designation 7F.04). Each has a capacity of per hour, and per hour when combined with the HRSG. Heat recovery, performed by two Vogt-NEM three-pressure reheat HRSGs, uses waste heat from the combustion turbines to generate steam to power an additional turbine. This steam turbine, also made by General Electric, is a model D11 tandem compound