Ford Island, just across Pearl Harbor from Oahu, Hawaii, served its part in history early on Sunday morning, Dec. 7, 1941. The mile-and-a-quarter-long islet’s tarmac airstrip is still scarred with 65-year-old strafing gunfire patterns, and the hulk of the USS Arizona battleship lies sunken in the harbor.
But today, Ford Island is the focal point of a comprehensive five-year multimillion-dollar U.S. Navy redevelopment project that will include construction of a new conference center, the $240-million headquarters of the Pacific National Oceanographic and Atmospheric Administration, the Pacific Aviation Museum, the Pacific War Fighting Center, and 2,000 housing units, at a cost of $84 million for the civilian and military personnel who will live and work on the island.
It was immediately apparent that the island’s existing power capacity would be inadequate for the projected energy demands of the planned complex and infrastructure, so local utility Hawaiian Electric Co. Inc. (HECO), Honolulu, was awarded a $22 million contract to install a new substation and two 46-kilovolt (kV) circuits that would have to be pulled under Pearl Harbor, a distance just short of a mile. This would provide a total potential of 50 megavolt-amperes capacity for the island.
When electrical contractor American Electric Co. LLC, Honolulu, learned that the bidding process for the cable pull was underway, it began discussions with the companies competing for the general contract.
Mark Fischbach, the firm’s executive vice president, developed a comprehensive risk analysis profile of the operation.
“I stressed that the length and complexity of the pull would require extremely close coordination among the players and getting my points across almost required divulging confidential estimating data,” said Fischbach.
The prebid discussions paid off, because when Hawaiian Dredging Construction Co. (HDCC), Honolulu, was awarded the general contract, it tapped American Electric to be the electrical sub.
“This pull would be pushing the envelope as far as technology and equipment were concerned,” Fischbach said. “I had heard a story about a longer pull of approximately 7,000 feet on the East Coast, but that involved much smaller cable.”
In this case, the 3-inch-diameter 1,750 MCM 46 kV cable would weigh 8 pounds per foot. Each 5,300-foot reel would tip the scales at 48,000 pounds.
For the pull, there would be twin mile-long, 24-inch-diameter steel casings each containing four high-density polyethylene (HDPE) ducts, three of them 6 inches in diameter for the 46 kV cable and another for a spare. In addition, there was a 5-inch duct for fiber optics and a 2-inch duct for ground wire.
Despite all measures taken to ensure coordination in the prepull stages, both HDCC and American Electric had to adapt to circumstances that weren’t included in their original calculations.
Originally, HDCC had planned to do their pipeline preassembly immediately adjacent to the island’s airstrip, and American Electric was initially given permission to locate its cable storage yard near the south end of the runway.
But at this point, the historical site preservation officials entered the equation, informing both companies that the runway had to be avoided, especially the bullet holes left from attacking Japanese warplanes that the authorities had delineated in green paint on the pavement.
Accordingly, HDCC had to move its planned preassembly staging area, requiring extensive coordination with American Electric. The 5,300-foot staging area was still close to the waterline at both ends of the island. Fortunately, the cable storage area was just shy of the strafing marks.
“Besides struggling with all the interlocking technological and mechanical problems, we also had to take into account these unique cultural and historical considerations,” Fischbach said.
And, history would also be an issue in the actual underwater horizontal drilling for the casings, with special care needed to thread the pipestream through the harbor bed so as to avoid the memorial to the USS Arizona and also overcome magnetic interference from the World War II submarine USS Bowfin exhibit close by the bore entry pit on Oahu.
Adapt and improvise
Unforeseen delays due to various causes had set the project back slightly by the turn of the year, so original plans to pull the cable through the casing above ground on the island were scrapped in order to make up time. The cable would have to be pulled after the casings were in place. But this raised new questions about cable tension and equipment capabilities.
Fischbach decided he needed to reconfirm the calculations he had done months before in order to accommodate the altered situation. He obtained engineering survey data on the proposed casing preassembly layout from HDCC and also drawings from the boring subcontractor, Laney Directional Drilling Co., Humble, Texas.
Among the team American Electric had assembled for the pull was American Polywater, Corp., Stillwater, Minn., manufacturer of cable lubricants. Of critical importance was the fact that the company’s president, John Fee, had developed a proprietary software program called Pull-Planner 2000 for calculating the variables involved in any given cable pull.
Fortunately, the resulting calculations revealed that the pull on the island would be 8,500 pounds and the pull under the harbor some 7,900 pounds, both safely under the cable’s tensile limit of 14,000 pounds. Once this was established, American Electric agreed to pull the cable through the submerged casings.
The challenge at this point was to devise a way to handle and install the cable without damaging it or exceeding its tensile limits and 60-inch minimum bending radii.
Fundamental to the operation was a 20,000-pound capacity cable puller called the T-UDP-240, made by the Wagner-Smith Equipment Division, Lawrenceville, Ill.
According to Fischbach, the unit was chosen not only for its capacity but because it was equipped with a digital screen and readout providing real-time monitoring of pulling tension, pulling speed and length of cable being pulled. In addition, there was a software interface for a laptop connection so that the whole pull could be viewed on a chart as it was taking place, and the chart could be saved as a permanent record of the job. Three pieces of customized equipment, fabricated for the job at hand, were key to the successful completion of the pull.
American Electric located a specialized equipment manufacturer, HisBusiness Inc., Laguna Beach, Calif., and commissioned two cable-handling components. The first was a series of 10 roller devices mounted on a 20-foot flatbed truck that would guide the cable off the 12-foot reel, across the back of the truck and down into the manhole where the casing terminated.
Then, to take the back tension off the cable reel during pulling, a second motorized variable-speed-drive roller unit was designed that would spin the reel and feed the cable off as it was pulled.
Lube application was the next hurdle, and Fischbach was aware of a foot-actuated lubricating device called the SoaperMonkey, manufactured by WLD LLC, Manchester, N.H.
As the cable is fed into the conduit, the lube is pumped directly from a standard 5-gallon bucket through a supply hose and into a split fitting that wraps around the cable ensuring even application. This requires only one operator, not two workers, which is the case with manual lubrication.
The equipment was ideal for the job, but there was one drawback—each of the six cable pulls would require 75 to 80 gallons of lube, and given the calculated speed of the pull, the crew would not have time to be incessantly replacing 5-gallon buckets.
Fischbach found out that the American Polywater lube was available in 55-gallon drums, so he called WLD and asked if they could customize a unit for use on a drum that size. A prototype was engineered and delivered, dubbed the SoaperGorilla. It worked with total efficiency when tested, and subsequently the manufacturer has made the unit available as a standard model.
American Electric was ready for the pull.
The proof is in the pulling
The first six pulls—three of 400 feet and three of 850 feet—took place in early October 2005 to connect a site near the casing bore entrance on Oahu to two existing HECO overhead line circuits.
Twelve pulls of approximately 1,000 feet each, followed in November, six to the new HECO substation and six to a site near the casing bore exit on Ford Island in December. Scheduling of these pulls had to be closely coordinated with HDCC’s duct bank and manhole work on the island.
The final six pulls under the harbor were completed in January and February and were followed by splicing, arc proofing and grounding. The two lines were energized on February 24 and 28—ahead of HECO’s “power on” deadline of March 3.
At this point, Fischbach said, the power is available for the anticipated needs of the entire Ford Island redevelopment project. The lines under Pearl Harbor will service the entire island including existing homes and new structures, the museums and any future construction that will continue for the next few years. EC