Duke Energy is part of the Duke family of companies, which constructs and operates power plants worldwide. Duke Energy is a global energy company with more than $26 billion in assets, and is the largest electric and gas entity in the nation. On July 1, 1998, Duke Energy purchased the seven generating units and support facilities of Moss Landing Power Plant (MLPP) from PG&E as part of the utility's divestiture of fossil-fueled power plants and the transition of the California electric generation market to a competitive market.

The MLPP is located on the eastern shoreline of Moss Landing Harbor. This medium sized harbor, which provides dock space for approximately 600 commercial and recreational vessels, is located about 110 miles (177 km) south of San Francisco. Moss Landing Harbor is located roughly midway between Santa Cruz and Monterey, California and is open to Monterey Bay. The plant is located in a relatively undeveloped area that includes industrial facilities, agricultural lands, sparse residences, recreational beaches, and tidal wetlands.

Duke Energy teamed with Duke-Fluor Daniel to create a design, construction and operation team to develop a state-of-the-art power plant entirely within the existing MLPP. The MLPP currently produces 1,500 MW from two 180-foot-tall steam boiler structures (Units 6 and 7) characterized by an intricate maze of piping, with walkways and structural steel. Associated with Units 6 and 7 and considered as local landmarks are two 500-foot-tall stacks. In addition, the MLPP site includes retired Units 1 through 5 and their associated boiler structures, steam turbines and eight 225-foot-tall stacks.

The MLPP has two separate intake structures in Moss Landing Harbor for withdrawal of cooling water that is necessary to remove excess heat from the power generation process. One intake previously serviced the now retired Units 1 through 5 and is currently unused and a second intake structure services the presently operating Units 6 and 7. Cooling water from Units 6 and 7 is discharged into Monterey Bay through two (one/unit) subsurface conduits. Historically, cooling water from Units 1 through 5 discharged into Elkhorn Slough.

The Project is designed to minimize environmental impacts and maximize the efficiency of the MLPP. The design includes utilization of existing once-through seawater cooling water intake and discharge structures. To assure protection of the Elkhorn Slough, Duke Energy will spend considerable sums to redesign the cooling water system used to supply Units 1 through 5. This redesign will enable the new combined-cycle units to utilize the existing Units 1 through 5 intake structure located in Moss Landing Harbor and the existing Units 6 and 7 discharge structure, thus eliminating any discharge into Elkhorn Slough.

The Duke-Fluor Daniel team contracted with Ameron International's Water Transmission Group in late 2000 to manufacture and deliver the redesigned cooling water supply (CWS) and cooling water return (CWR) piping for the new system. Ameron worked closely with the Duke-Fluor Daniel team throughout the design process and assisted with the pipe design criteria. The project used AWWA C300 Standard for Reinforced Concrete Pressure Pipe, Steel-Cylinder Type on the 4,700 linear feet of parallel 84-inch diameter CWS and 1,200 linear feet of 120-inch diameter CWR pipelines. Selection of the rigid Reinforced Concrete Cylinder Pipe (RCCP) resulted in a strong self-supporting large diameter pipe for the owner that would not have been provided by other large diameter flexible pipe. Cement mortar lined and coated steel pipe ranging in size from 24-inch to 48-inch diameter was used for the various connections to structures and the new generating units. The delivery of the piping was completed weeks ahead of the project schedule in July 2001.

Duke Energy is replacing the 1950s technology of Units 1 through 5 with two 530-MW high efficiency combined-cycle (CC) units, and removing Units 1 through 5's eight existing stacks. Each combined-cycle unit will consist of two advanced class combustion turbine generators, two heat recovery steam generators, and a single steam turbine generator. Only the new steam turbine generators will require a significant amount of ocean cooling water. About two-thirds of the total new power output will be produced by the combustion turbine generators, which require no ocean cooling water.

In addition, Duke Energy will upgrade existing Units 6 and 7 through replacement of the high-pressure rotor and increasing the steam flow rate, which will result in an additional 73 MW per unit of generation capacity. These two actions combined will yield an additional 1,206 MW (i.e., 1,060 MW + 146 MW).

The Project is scheduled over a 29-month construction period. Initial startup of the new 1,060-MW facility is planned one month after construction is complete, with full-scale operation expected three months later. Based on a construction start in winter 2000, initial startup would occur in summer 2002 and full-scale operation would commence in fall 2002. The Unit 7 upgrade is scheduled to be operational in December 2001. The Unit 6 upgrade is scheduled to be operational in June 2003.

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