Aqua Cutter HD-6000 Unsinkable Against 65-Year-Old Concrete at Pearl Harbor
Aqua Cutter HD-6000 Unsinkable Against 65-Year-Old Concrete at Pearl HarborEfficient AquaJet Systems hydrodemolition robot proves to be an invaluable investment for Triton Marine Construction
STURTEVANT, WI (May 1, 2007) – Delaminated concrete on Pearl Harbor’s Wharf F12 and Wharf F13 is being removed at a rapid pace by Triton Marine Construction’s Aqua Cutter HD-6000 hydrodemolition robot. The concrete deck is being restored as part of the U.S. Navy’s renovation on both wharves which were originally constructed at Pearl Harbor’s Ford Island facility in 1942.
The hydrodemolition of the 65-year-old concrete is just one of many projects in the U.S. Navy’s plan to bring all wharves, dry docks and piers at Pearl Harbor up to par. Supporting the entire Pacific Ocean, the harbor sees a vast number of ships stationed and transiting through each year, according to Tim Couch, project manager for Nova Group, Inc., the general contractor on this project. In addition to the concrete removal, Couch says that other renovations occurring on both wharves include new piles being installed to absorb ship docking impacts and pile repairs below the deck.
“The U.S. Navy is always looking at ways to improve their capabilities on wharves and waterfront utilities,” notes Couch. Re-vamping of both wharves started in early 2006 by the Napa, California-based Nova Group, Inc.
Triton Marine Construction, based out of Bremerton, Washington and a sub-contractor to Nova Group, Inc., was thrilled when they were approached to use their AquaJet Systems HD-6000 hydrodemolition machine on the Pearl Harbor project, according to Steve Yuhl, supervisor for Triton Marine Construction.
“We’ve worked with Nova Group, Inc. on a number of concrete restoration projects over the past three years and we’re pleased that Nova Group, Inc. wanted to work with us again,” says Yuhl. “We knew our newly purchased HD-6000 would help progress the project in an efficient manner with its fully computer-controlled system, outstanding maneuverability and its efficient cutting head.”
Nova Group, Inc. selected Triton Marine Construction for their highly-respected reputation, capabilities with their HD-6000 unit, and their extensive experience with concrete restoration. “The use of the HD-6000 reduced the number of laborers needed on the job site,” Couch says. “That means cost savings and improved on-site safety.”
Distributed in the United States exclusively by the Water Technology division of Putzmeister America, Inc., AquaJet Systems models offer power, flexibility and control. The company’s 3,500 lb. Aqua Cutter HD-6000 features versatile horizontal operation on almost any surface requiring hydrodemolition.
According to Bret Gordon, superintendent on the Pearl Harbor project with Triton Marine Construction, this project was the perfect opportunity to test and become familiar with the HD-6000 before taking on the company’s more time sensitive and larger scale projects. This includes the Highway 1 Airport Viaduct project near the Honolulu International Airport, which will require the HD-6000 to be on-site for two years and meet demanding, short closing times.
“It would take three to four times as long using our conventional method of removing concrete with hammers and chipping guns,” notes Gordon. “With the speed and performance of our HD-6000, we see hydrodemolition as the best solution for our upcoming projects and the future in concrete restoration as a whole.”
The HD-6000 arrived on the Pearl Harbor job site in November 2006. In January 2007, Putzmeister Water Technology personnel, including Eric Zimmermann, general manager of Putzmeister Water Technology, provided a two-day on-site training course at the Pearl Harbor job site for Triton Marine Construction’s employees on the HD-6000.
“The training by Eric Zimmermann and the rest of the Putzmeister Water Technology crew was incredibly helpful,” says Gordon. “With Putzmeister Water Technology’s expertise, we knew what kind of powerful performance we could expect with the HD-6000. We also gained proficiency in adjusting parameters such as cutting width, speed and angle of the jet. With our extensive training, operating and setting up the unit was fast and easy.”
After the training was complete, the unit worked on the site for a few days in January 2007. Following the arrival of a delivery vacuum truck for debris removal that would keep up with the fast pace of the HD-6000, the remainder of the project was completed in March 2007.
According to Gordon, the tasks for Triton Marine Construction’s HD-6000 on the Pearl Harbor job site included removal of selected areas of the weak concrete and any corroded rebar from the decks of the two wharves located in two individual areas.
“The concrete being removed was measured at 6,000-psi containing very soft aggregate,” says Zimmermann. “The aggregate in the concrete consisted of black porous crushed stone which is believed to be volcanic in nature.”
The reason the concrete deteriorated was due to much less stringent specifications and quality control on concrete mixes as there are today, according to Gordon. “Over the years the concrete started breaking down and eventually allowed holes where water was able to enter through.”
“The production rate of the concrete removal using the HD-6000 for both wharves was three sq. ft. per minute at a four-inch depth (one cu. ft. per minute) in just over one minute,” according to Zimmermann. “This is an exceptionally high production rate. A total of 3,000 sq. ft. of concrete was removed from the decks of both wharves.”
“The high production rate would not have been possible without the HD-6000’s flexible and compact design,” notes Gordon.
Because only selected parts of the concrete on Wharves F12 and F13 were deteriorating, the HD-6000 was required to only work on certain sections. “The removal of concrete in only selected areas on both wharves required resetting the parameters of the HD-6000 on each individual section that needed to be removed,” says Gordon. “Each section was a different shape.”
The HD-6000 minimizes the amount of good concrete that is removed. “By adjusting the traveling range of the lance and the distance moved by the machine, the passage of the machine’s jet is determined,” Gordon comments. “This means hydrodemolition is only carried out on the deteriorating concrete with no harm to the surrounding, good concrete.
“The HD-6000 also proved invaluable because the tractor did not have to realign for most areas. The proximity switch adjustment facilitated easy adjustment for varying widths of the individual areas,” continues Gordon.
In addition, the distance the machine traveled was easily controlled through visual markers set outside the concrete removal area.
“The movement time between patches of concrete that needed to be removed would have increased and the overall production rate would have been significantly reduced without the efficient parameter adjustments provided by the HD-6000,” comments Zimmermann.
The HD-6000’s forward movement and the oscillation of its head was easily adjusted specifically to each area of concrete that needed to be removed. According to Gordon, just one or two passes with the HD-6000’s high pressure jet head were needed to remove the weakest areas of the concrete to the required depth.
“We’re very happy overall with the performance and ease of use the HD-6000 has provided us on this project,” says Gordon. “The HD-6000 was a big investment that is sure to pay off for our company, as well as our customers’ business, as we plan to use the machine for many years to come.”
According to Couch, Triton Marine Construction has been on-site since November 2006 working on top deck repairs of both wharves using its conventional concrete removal methods, in addition to the HD-6000 for the horizontally deteriorating concrete. Some repairs include demolishing 1 ft. wide by 10 in. thick curbs.
“We are very pleased with the progress Triton Marine Construction has made with the HD-6000,” says Couch. “We have already contracted Triton Marine Construction’s HD-6000 for another project, a dry dock floor at Pearl Harbor that is 200 ft. wide by 1,000 ft. long by 60 ft. deep (the length of three football fields) which will occur this year.”