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Delicate Drilling under Pearl Harbor

Trenchless Technology, December 2002

A 2,000-ft bore required some expert maneuvering and pre-planning to avoid disturbing the historic memorials at Ford Island.

By Sharon M. Bueno, Editor

Ford Island near Oahu, Hawaii, isn't just any site for a major infrastructure project. In taking on this project, the contractor must be mindful of what took place on the island some 60 years ago and what it means to the military, visitors and the people of Hawaii.

Ford Island is a 450-acre site at the heart of the Pearl Harbor Historic District. The island was acquired by the U.S. government for Army and Navy development and was transformed into a major air facility in the late 1930s. It is adjacent to what is known as Battleship Row. Shortly after the first wave of Japanese aircraft flew over Pearl Harbor on December 7, 1941, the USS Arizona exploded and sank with 1,777 of her crew. All told, 21 vessels were sunk or damaged.

Ford Island is now hallowed ground in memory of the worst attack on U.S. soil that occurred prior to September 11, 2001. The island is home to the Arizona Memorial and the USS Missouri Battleship Memorial.

Recently, HMS Construction Inc., San Marcos, California, took on the challenge of directionally drilling a 2,000-ft. bore of 20-in. of HDPE as part of a massive wastewater line project for the United States Naval Facilities Engineering Command, Pacific Division, at Ford Island. The new line was drilled from Ford Island to the intermediate pump station located on the Pearl Harbor Naval Shipyard. This project will also allow for the increased capacity for future development on the island.

HMS Construction learned of the project through the Naval Facilities Engineering Command electronic solicitation Web page in April 2001 and started contacting primary contractors about bidding on the job. HMS Construction eventually hooked up with RCI Construction Group and was hired to serve as the subcontractor. The job occurred over a 20-day period in January 2002. According to HMS Construction president Mike High, HDD was only a portion of the sewer force main installation; the project also included upgrading the two pump stations located at either end of the project.

"When we first arrived and reviewed the jobsite, it was like we had gone back in time," High says. "On Ford Island, the original World War II runway was still there. The original World War II sea plane aircraft hangars and water approach ramps looked as if you could open the doors and out would come vintage planes ready for a mission."

High also notes that the apron areas had locations where bombs and machine gun strafing were still visible from the December 7, 1941 attack.

"We have worked on various military facilities throughout the past few years and have found that the Pearl Harbor Naval Station to be the most active in regards to preservation of existing facilities," High Says. "To preserve this, the Naval Station has personnel assigned to monitor construction in these sensitive areas."

High says the contractors met with the coordinators, who noted, for example, which areas would only be open to foot traffic. "In fact, on the project's blueprints, bomb divots were identified for us to protect during the construction," he says.

The Drill Site

The drill site was set up on the Naval Shipyard side of the bore - an area also know as Hospital Point and an area on the edge of base housing. The bore was designed to be drilled from this location under the harbor entrance to Ford Island. High notes that the bore when under the original World War II sea plane approach rams and apron bomb divots. The pipe fusing and staging area went past the sea plane hangers and across the Ford Island runway.

"Every day traveling to the jobsite, you were reminded of the sacrifices made there as you drove over the Ford Island Bridge observing the USS Arizona Memorial," High says.

HMS Construction employed an American Augers DD330 330,000-lb drill rig for the job, as well as American Augers MP300 and P600 Mud Recyclers and a 600-gpm mud pump from National Oil Well. M9I HDDD, Mining and Water Well supplied drilling fluids and locating systems were from Sharewell, Inc.

High says that the most challenging aspect of this project - beyond the obvious of not damaging, let alone disturbing, any of the historical objects and memorials that make up Pearl Harbor - was the logistics. The cost of mobilizing to Hawaii is expensive and he explains that there are only two ways to transport all of the equipment to the site: by sea cargo or by air cargo. HMS Construction shipped its equipment via a three-week sea trip.

"We had to plan for the conditions we felt we were going to encounter and not bring more than what we needed," High explains, noting this example, "During the drilling process, we had anticipated much harder ground conditions so we had brought tooling to drill basalt and hard coral."

The bore itself went through a variety of differing ground conditions - including limestone, coral cobble, coral voids, volcanic tuff and 0-blow count silts - and the crew drilled more than 100 feet under the harbor channel. One of the more challenging aspects of the bore was that the borepath went from sections of volcanic tuff into approximately 1,000 feet of the 0-blow count silt and then back into consolidated formations of volcanic tuff.

High credits the thorough geotechnical information provided by James Kwong and URS Corp.'s office in Hawaii for his crew knowing how to handle the complex ground conditions as they surfaced. "The coral and limestone cut like butter with our tooling, however, the volcanic tuff gave us some excitement," High explains. "The material looked and reacted like expansive clay. Our cutting rate came to a screeching halt when we hit it. When we pulled back, our tooling was packed and gummed up. Being where we were, we decided to field-modify our tooling instead of air-lifting new tooling."

High says the Navy was impressed with the accuracy of the bore, adding that HMS and RCI were hired to handle an additional 3,500 feet of directional drilling via four land crossings, which were originally supposed to be done using open trenching methods. This part of the project - which involved bores of 600, 750, 900 and 1,000 feet - was completed in May 2002.

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