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Fort Delaware Uses Helical Technology For Upgrades And Enhancements
Pea Patch Island, a small, approximately one-mile-long island, sits in the channel of the Delaware River near the entrance to the Delaware Bay. Strategically located, its storied military history began as early as the 1790s when Pierre L’Enfant proposed its use in the defense of Philadelphia and Delaware. It is home to Fort Delaware, previously an active fort, but now one of the Delaware State Parks. Its strategic location, however, is not limited to its military value. Pea Patch Island, a wetlands stopping ground for migratory birds along the Atlantic Flyway, has been designated as an Important Bird Area by the Audubon Society.
Pea Patch Island now serves as a tourist destination, focusing on its history and environmental significance. Exploring the fort is not its only attraction. Bird watching is a rewarding pursuit. According to the Fort Delaware State Park website, “The Pea Patch Heronry is one of the largest mixed species nest colonies for herons, egrets, and ibis in the eastern United States. Other nesters on the island include osprey and bald eagles.”
The administrators for Fort Delaware State Park decided to enhance the birding experience for visitors by adding an elevated walkway and raised pavilion to one of the popular pedestrian trails. The new lookout is directly across from the heron rookery. At the same time, they decided to build a new maintenance facility. Both projects required eco-friendly deep foundations.
The construction challenges were typical for remote location projects. All the material and equipment had to be transported to the island by ferry. Because the installation team was ferried to and from the island by boat, manpower hours were dependent on, and limited by, the 6 AM – 7 AM departure and 4 PM return ferry schedule. The tight Spring schedule and frequent inclement weather events in the middle of a river created uncomfortable working conditions and frequent construction delays.
The walkway/pavilion site was remote with limited access. Equipment and material transportation was restricted to a rough low-lying secondary trail that was frequently inundated with water. The installation crew had to walk almost a mile from the ferry dock to the walkway location by a separate trail. Environmental sensitivity required the installing contractor, RE ECO Drill LLC, to be mindful of the impact on the flora and fauna in addition to the soggy trail the equipment and materials had to traverse. On the day that I was on-site, a front-end loader with a load of helicals got stuck and had to be pulled out by another piece of equipment sent to the rescue. It was not the first such incident. In addition, only a limited amount of material could be stored on-site, requiring frequent trips through the muck and mire. A Yanmar 87 E Pro easily and gently negotiated the site and installed 28 IDEAL 3.5” pipe piles to 45’ to achieve the 23 kips compression load. Five 1.5’ Square Shaft batter piles were used to achieve the required 2 kips in tension. Click here to read Pea Patch Island Walkway Case Study.
Installing the foundation for the Maintenance building was a different story. The site of the Maintenance building, adjacent to the prison, was a shorter walk and more straight forward from an installation standpoint. Forty IDEAL 3.5” pipe piles were installed 60’ on a grid to achieve the 100-kips ultimate. Since access was not an issue at this location, a Caterpillar 312 excavator, provided by the GC, Merit Engineering and Construction, was used for the install. Click here to read Pea Patch Island Maintenance Building Case Study.
Many of our installers have installed helicals on islands throughout our territory in addition to other remote, environmentally sensitive locations. This was not installing contractor Art Kozoil’s first rodeo as he is an experienced hand in the muck and mire. Click here to read Maurice River Redux.
Experienced walkway/boardwalk installers, utilizing small minimal impact equipment and a product packaged in bundles, are adept at working remotely in challenging environments. The new walkway, pavilion, and maintenance building constructed on Pea Patch Island, in the middle of the Delaware River, in Fort Delaware State Park, are just the latest examples of how flora/fauna friendly helical piles can make the difficult, possible. Click here for walkway case studies.
by Pat Haffert
Danbro Vice President