CARBON AND CONVERSE COUNTIES, WYOMING

Tetra Tech provided engineering, procurement, and construction (EPC) services for the Glenrock, Rolling Hills, and Seven Mile Hill wind farm projects in Wyoming. Tetra Tech served as the prime contractor on these three wind energy projects, totaling approximately $150 million, for PacifiCorp Energy, a Mid-American Energy Holdings Company and one of the leading utilities in the western U.S. Each of the three wind projects included 66 General Electric (GE) 1.5sle megawatt (MW) turbines and each has since expanded to 79 turbines. The total generating capacity of each project is 118.5 MW of power. Awarded in January 2008, work on the three projects began in March 2008. All three wind farms were brought on-line in February 2009.

The Glenrock and Rolling Hills projects are located in Converse County, Wyoming, on 14,000 acres wholly owned by PacifiCorp Energy. Sited on the former Dave Johnston Coal Mine, this is the first wind farm in the country to be developed on a reclaimed strip mine. The Seven Mile Hill wind project is located in Carbon County, Wyoming, between the towns of Hanna and Medicine Bow.

The scope of work for the three wind projects consisted of:

• Erect and install 237 GE 1.5 MW wind turbine generators, their associated underground and overhead collection systems, and six meteorological towers;
• Construction of approximately 60 miles of access and site roads, laydown areas, and the modification, repair, and maintenance of all existing public roads at project boundary;
• Constructed project and interconnection substation facilities, which include an office, warehouse, maintenance, and associated control buildings;
• Designed and constructed multiple foundations types (Spreadfooting, H-Pile, Micropile, and Deep Dynamic Compaction), structures, and building refurbishment;
• Maintained compliance with necessary permits and approvals from local, state, federal, and other authorities through an environmental construction compliance plan.

Tetra Tech identified cost savings by moving the Seven Mile Hill substation on the hill instead of in the valley.

This is the first wind farm in the country to be developed on a reclaimed strip mine.

PERFORMANCE HIGHLIGHTS

• Tetra Tech executed three major wind EPC projects concurrently, consisting of 237 wind turbines, a clear indication of PacifiCorp’s confidence in our level of expertise and the financial strength of our corporation to stand behind our work
• Tetra Tech mobilized immediately, beginning the project with little lead time and completing the design concurrent with construction activities.
• Tetra Tech identified cost savings associated with earth-moving during construction and with road maintenance during winter conditions by moving the Seven Mile Hill substation to a more cost efficient location