Central Maine Power Co. (CMP), a subsidiary of Iberdrola USA, has completed construction of four 370-ft, lattice towers that will carry transmission lines over the Penobscot River in Maine. The towers and 345 kV transmission lines are part of the Maine Power Reliability Program (MPRP), CMP’s $1.4 billion investment in its transmission system. During a four-day operation from June 21 to 25, an Erickson Air-Crane heavy-lift helicopter hoisted sixteen sections of lattice tower into place as crews on the structures bolted the sections together.
“Completing these towers marks another milestone for CMP, Iberdrola USA, and the MPRP team,” says Doug Herling, vice president for Special Projects at CMP. “These towers are the tallest structures in the MPRP, and the half-mile span across the river is the longest in the project.”
The Penobscot River crossing includes two towers in the town of Winterport on the west side of the river and two towers in Bucksport on the east bank. The towers were assembled in four sections up to 60 ft wide and weighing more than 17,000 lb each. Once the transmission lines are in place, they will span 2,419 ft across the river with a minimum clearance of 177 ft above the river.
“This was a complex operation involving highly specialized equipment and training for crews in the air, on the towers, and on the ground,” said Herling. “It also required considerable coordination with federal, state, and local authorities for air traffic control, roadway safety, and other public safety measures. Everyone involved deserves credit for their part in the safe and successful completion of this project.”
The MPRP will ensure the long-term reliability of CMP’s bulk power system. The project includes the construction of five new 345-kV substations and related facilities linked by approximately 440 mi of new transmission lines. The new facilities will reinforce the backbone of the company’s 40-year-old bulk power system and create greater capacity for the integration of new generation in the New England region.
The MPRP is the largest construction project ever undertaken in Maine. More than 2,700 people are employed directly in the construction, and a 2009 economic impact study projected that the construction spending would generate as many as 900 more jobs through indirect and induced employment. Begun in September of 2010, the first new 345 kV substation will be energized later this year. The company expects to complete construction in mid-2015.