Demolition of a former U.S. Coast Guard pier in historic New Castle, N.H., is under way by Reed & Reed Inc., as the contractor builds a new pier for the University of New Hampshire's (UNH) marine research program.
The Woolwich, Maine, contractor has a $5.7-million contract to construct the pier to serve as a home berth for the university's coastal research vessels as well as a catamaran-style coastal mapping vessel that is currently being constructed for the National Oceanic and Atmospheric Administration (NOAA). Construction of the pier is being paid for with funds originally provided in a 2001 grant from NOAA. As with the existing pier, fish pens associated with UNH's Open Ocean Aquaculture research program will be housed under the pier. Floating docks and a gangway will also be built as part of the contract.
Reed & Reed originally planned to mobilize in mid-November 2006 and bring barges and cranes to the job location. Project specifications require major construction equipment and materials to be remotely staged and barged to the site, and demolition debris from the pier to be removed from the site via barge for off-loading elsewhere. However, unusually high seas delayed the project for several weeks, according to Mark Buckbee, P.E., the contractor's project manager.
"The swells were too large so we waited it out. Although we only have about seven months to do the job, we juggled our schedule to make up the lost time and expect to meet the project deadline," said Buckbee.
According to UNH, the project originally was to include construction of a new research laboratory adjacent to the pier in New Castle, but deed restrictions prohibited any impact on historic resources at the site, including Fort Constitution. Originally an earthwork defense built on the site soon after New Castle was settled in 1623, the fortification became known as Fort William and Mary, was given to the United States by the State in 1791, and was rebuilt and renamed Fort Constitution in 1808. Eventually, a U.S. Coast Guard Station was built near the fort, and the pier now being demolished was used as a berth for a cutter which has since been moved to Portsmouth Harbor.
As bids started coming in, the apparent cost of the research lab was much higher than expected. As well, the requirements to investigate historic resources and develop acceptable plans to preserve and maintain those resources would add years to the process. And in the meantime, construction costs would be spiraling upward every year.
In light of this, UNH officials abandoned the plan to build the lab and confined the scope of the project to the construction of the new pier, deciding to use the remaining NOAA grant to meet high-priority marine lab needs on campus and at other existing UNH facilities.
The original pier, built in the early 1970s, has a foundation of rock-filled, creosoted timber cribs supporting a precast concrete deck and a cast-in-place concrete overlay. Reed & Reed is self-performing most of the demolition and construction, employing three barges — two carrying 80-ton LS-518 cranes and a third barge with a Komatsu 400 excavator. One of the Link-Belts is being used as a service crane, while the second, equipped with a clamshell, and the excavator are demolishing the existing pier and loading debris on a barge for ferrying to shore and ultimate disposal. Barges are maneuvered and towed by the contractor's two Inland tugs, each with twin screws and two, 250-horsepower marine engines.
To remove the deck, crews sawcut the concrete overlay in patterns matching the seams of the underlying precast slabs. This allowed them to remove sections of both the overlay and precast slabs at the same time.
Once the existing pier has been razed, construction will begin in earnest on the new pier. Designed by Appledore Engineering Inc. of Portsmouth, N.H., the pier consists of a 101-foot by 24-foot trestle section, and a 329-foot by 28-foot pier section. Trestle and pier are supported by 17 bents spaced approximately 25 feet on center, each bent comprised of two, 30-inch-diameter battered steel, concrete-filled piles topped by cast-in-place concrete caps measuring roughly 4 feet by 6 feet. Piles in turn rest on 6-inch-diameter rock dowel sockets ("stinger" piles). Reed & Reed is driving the 30-inch piles using an ICE 216 vibratory hammer, except for the bottom 2 feet, for which a Delmag D36 impact hammer is employed to seat the piles about 2 feet into ledge. A subcontractor, Terra Drilling of Hudson, Mass., is installing the stinger piles. Terra drills 12-inch-diameter holes about 13 feet into the ledge, inserts the 6-inch stingers, and grouts them in place. Then Reed & Reed fills the 30-inch piles with concrete, and forms and pours the caps.
On top of the pile caps, the contractor will place two, longitudinal precast edge beams. These will shoulder transverse 4-foot by 15-inch-thick precast concrete planks and a thin cast-in-place concrete overlay.
The new pier is expected to be ready for use early in summer 2007. In commenting on the project, Jonathan Penncock, director of the UNH Marine Program, said, "The replacement pier will provide essential berth space for the small fleet of UNH vessels, and access to the seawater environment, both of which are critical for the university's world-class, $35-million per year marine research activity."
(Key personnel for the construction of the new pier are: for UNH, Richard Rouleau, P.E., facilities project manager; for Appledore Engineering Inc., Craig Morin, P.E., project manager, and Richard Beckwith, P.E., on-site representative; and for Reed & Reed, Mark Buckbee, P.E., project manager, and Scott Stanchfield, project superintendent.)