In October of 2017, Crofton began a transmission tower rehabilitation project on three towers located near Clarksville, Virginia, on the shores of Kerr Lake.
Two of the structures were accessible via power line right-of-way land access however, one of the three structures were only accessible by barge. The greatest challenge associated with the waterborne structure was transporting concrete from the land-based trucks on to the barge and then into the foundation forms at the tower.
Shortly after mobilizing and completing initial excavation work at the first land-based structure, Crofton was informed by environmentalists that there was an active Bald Eagle nest on the waterborne structure. All work on this structure would have to be completed by December 15th. Time was of the essence.
With only a little over a month to complete work at that structure, the crew had to act fast. Crofton personnel quickly mobilized sectional barges to create a 30’ x 60’ floating platform which would be used to transport earth moving equipment and materials to and from the tower structure. Within three days of notification, materials and equipment were on site and work commenced. Two weeks prior to the deadline, concrete trucks were brought in through the nearby right-of-way, 1500 feet from the tower location. The concrete was unloaded by a pump truck into empty concrete hoppers on a waiting barge. Concrete was then transported to the tower and deposited into the concrete forms. Each transmission tower foundation required 7 trucks of concrete. The barge would hold one truck’s worth of concrete which made each foundation require 7 “round-trips” to the tower by barge!
Watch below to see how Crofton executed this critical phase of concrete mobilization!
Forms were stripped, and all equipment was removed by the deadline. The crew continued and completed work on the two remaining structures with access via land, completing all rehabilitation on these structures by the end of January 2018.
All three transmission towers were typical lattice-type towers each with four (4) cast-in-place concrete cylinder foundation piles. Over time and with the continuous rise and fall of water levels at Kerr Lake, soils eroded from around these foundations thereby reducing the bearing capacity or each foundation. The rehabilitation specifications required the installation of helical piles around the perimeter of each foundation, install reinforcing steel, and form and pour a 6’ 6” square foundation encompassing each foundation pile, embedded 2’ below the existing grade at each foundation. Due to permitting restrictions, no direct contact was allowed between ground and construction equipment. This required strategic placement of mats so that each of the tower foundations were accessible as well as the barges for retrieving materials.
It was a challenging work environment that presented numerous opportunities for creative thinking and collaboration. At Crofton, we pride ourselves on giving each project the same amount of safety, service, integrity, and innovation—no matter the size, scope, or complexity. Thanks to project managers Kurt Feairheller and Josh Will for their leadership and attention to detail, and to the rest of the crew for their ability to adapt and respond quickly to our client’s changing needs!
To learn more about Crofton’s past project experience, visit our projects page.
Want to learn more about Bald Eagle conservation? Visit The Center for Conservation Biology’s website.