The Hemingway site was graded at approximately 1.7% to maintain a flat surface and minimize the amount of soil excavation, Bracke says. “To maintain the natural drainage, a ditch system with water retention ponds was built around the station,” he adds. “The water-retention ponds slow the flow so that the natural drainage system is not compromised in case of a flood.
“The station also has an underground drainage system to move the water from the large station pad to the ditch system and water retention ponds. As the ponds fill, the water then exits into the natural drainage, leaving any sentiment carried by the water in the retention pond,” Bracke says.
Biggest to Date
Jason Kangas, project manager for the Nevada office of general contractor Energy Erectors, says the Hemingway project is the biggest substation that his company has built. The substation covers more than 68 acres, or 3 million sq ft. Construction on the substation started in February 2009, and at the height of construction, there were 90 to 100 people onsite.
Cole says Power Engineers worked with Idaho Power on the civil, electrical and mechanical engineering, but the inhouse control systems were done by Idaho Power. “We did the major design for everything inside the station fence except controls,” Cole says.
The fenced portion of the station includes 500-kV to 230-kV transformers, switching equipment, a control building, communications facilities and a microwave tower. The fenced area is large enough for future expansion.
About 3 million lb of steel construction materials were used and approximately 8,300 cu yd of concrete. The two-story control building is 14,000 sq ft.
One reason for the large size of the facility is that the spacing of a 500-kV line is 25 ft, compared to approximately 10-ft spacing on 345-kV substations.
The station is located on private property and not subject to federal environmental protection measures. Although not required to do so, Idaho Power followed most of the federal environmental-protection measures.
Owner: Idaho Power
Contractor: Energy Factors
Engineers: Power Engineers, Terracon Consultants