Emergency power replacement - a dam challenge for Bigge Crane and Rigging
By D.Ann Shiffler09 March 2010
Bigge Crane and Rigging started the New Year off with a large-scale emergency power replacement project that involved hauling and replacing power equipment at a remote dam in Lake McClure, California (CA), USA.
The Exchequer Dam Powerhouse in Lake McClure, CA is the sole power generator for three major counties in Northern/Central California. When the existing transformer needed replacing back in January, the company called on Bigge Crane and Rigging to manage the replacement process, a challenge that required rigging, lifting and transportation expertise on every level.
The job called for the replacement of an existing dual function transformer with two new transformers. The goal was to assure a safe, seamless operation, and that power generation never be interrupted.
Bigge performed three separate hauls from three locations. The first haul was to pick up the new transformer and haul it 175 miles to the dam powerhouse. The next haul was to pick up the second transformer and haul it 105 miles on a dual lane 8-dolly transporter. The last haul was to transport the existing transformer 45 miles to an offsite rail spur.
Bigge's role was to provide supervision, engineering, transportation and rigging equipment, crane support and labor. Due to the distance between sites, as well as the heavy crane, transportation equipment and rigging required to coordinate this job, Bigge used co-project managers working as a team to assure coordination among the crews. The teams were comprised of a transportation superintendent, a two-man heavy crane crew, and a five-man rigging crew. Co-project managers were Wayne Matheny and Frank Pavia.
A range of equipment was needed for the job, including a 600-ton Demag AC500 all terrain crane, a dual lane beam and 8-dolly transporter and a 6-line self propelled platform trailer. The Demag crane used multiple counterweight configurations to accommodate the lifts at the various places.
The new transformers were heavy and bulky. The first unit weighed 173,000 pounds and measured 18 feet 2 inches long by 10 feet 8 inches wide by 12 feet 2 inches high. The second unit weighed 310,000 pounds and measured 30 feet long by 11.5 feet wide and 14 and-a-half feet high. The unit that was being replaced weighed 195,000 pound and measured 24 feet long, 12 feet 6 inches wide and 13 feet 2 inches high.
The varied routes involved crossing into five counties, multiple cities and rural routes. Closer to the powerhouse, the crews navigated narrow roads as wide as the trailer and leaving inches on each side, multiple 90 degree turns, four main-line railroad crossings and traveling through two major cities during rush hour traffic. The mountain roads going into the jobsite had a 17 percent down and upgrade.
Assist vehicles included two pilot cars with height poles, multiple CHP units, wire pushing trucks, curb/shoulder support equipment vehicles for controlling the tight turns and obstacles, and two spotting vehicles. The permit process, engineering and coordinating started one month prior and two weeks to coordinate and perform the rigging, transportation, removal and setting of three transformers. Multiple permits were required by the state of California, and the trailers had to engineered and configured to meet the weight requirements for the state vehicle codes for over dimensional loads.
The most challenging part of the project was the access roadways in and out of the powerhouse. The access to the powerhouse was limited by an extremely narrow one-lane access road. On one side was a guard rail with a 50-foot cliff leading into the river and a vertical wall of rock on the other side.
Crews had to remove the crane and reconfigure the counterweight multiple times to allow access of the truck loads and rigging of the units. The transformers also had to be trans loaded onto various trailers before they could be hoisted and set. These circumstances required the co-project managers to have dialog between the crews to manage the execution of the equipment.
Additionally, weather was an element as heavy fog and rain prevailed from start to finish. The transportation crews had to stop on the route several times to wait out the fog, sometimes up to three hours. The operators also had to deal with heavy rains and wet conditions when hoisting and setting the transformers.
Extensive logistics were required to rig-in the crane and coordinate the trucks loads. Between loads, the crane had to be removed from the powerhouse and reconfigured to accommodate the lifts for each unit. All of the work was fully engineered, managed and performed by Bigge and all of the equipment used was owned by Bigge.
Despite all the challenges, Frank Pavia, Bigge project manager, says this is the type of project in which Bigge specializes. "These types of projects are perfect for Bigge," he says. "We have extensive experience in specialized hauling and have the engineering, skilled crews and equipment to safely complete complicated operations like this."
Wayne Matheny, Bigge project manager, says his team worked to use the most efficient equipment possible and to assure everything went off without a hitch. "We were able to utilize a single crane onsite with multiple configurations in coordination with the truckloads to save the customer's money," he says.