Successful Use of Engineer-Procure-Construct Helps Strengthen Nation's Power Grid
When MidAmerican Energy required a new high-voltage transmission line to deliver electricity from the Council Bluffs Energy Center to a new substation in Grimes, Iowa, they relied on Stanley Consultants to design a sustainable solution for their needs.
An engineer-procure-construct (EPC) contract was awarded to design and construct a new 15-acre 345/161 kV substation in Grimes, Iowa, along with 108 miles of new double-circuit 345/161 kV and 16 miles of 345/345 kV double-circuit transmission line, within existing line corridors, from the energy center to the new substation.
Engineering and construction occurred concurrently on this fast-track project. Built in five segments, the line contains 730 self-supporting steel poles ranging from 95 to 180 feet tall, and weighing up to 176,400 pounds.
Extensive outage restrictions and a fast-track schedule required construction of foundations 25 feet deep and 13.5 feet in diameter using low drill operations beneath energized lines to maintain power throughout construction. While not a common practice, extensive safety measures were taken and no accidents occurred during the low-drill operations.
The substation and new transmission line strengthen the nation's power grid by providing increased capacity to handle higher electrical demand. Rarely seen on large transmission and distribution projects, this successful use of EPC will alert other utilities that EPC is a viable alternative to design-bid-build.