Intercoastal Foundations & Shoring: ABI & Delmag Deliver Unbeatable Edge
Intercoastal Foundations & Shoring worked with difficult soil conditions and three different types of piles to complete deep foundation work at SkyViewParc, a 13-acre, $800 million mixed-used facility near LaGuardia Airport in New York. Throughout the project, two different sized ABI Mobilrams proved their versatility and helped the contractor push the envelope on production, said Andy Burns, project manager.
"With the ABI Mobilram, a single machine gave us the edge in different circumstances for different reasons. The machine's versatility was key -- it vibrates, it's capable of drilling, it can be used for impact driving. We were able to use the same machine to serve multiple functions on multiple pile types," Burns explained.
The site offered a variety of challenges, including as hallow water table and variable soil conditions. The upper layer consisted of 10 to 20 feet of loose fill with obstructions. Below that was 40 feet of fine silt and organic soil, then a layer of glacial outwash, more silt, and finally glacial deposits.
In areas where obstructions were a major concern,1,300 HP14x89 piles were driven to final depths of 100 to 150 feet. To limit the amount of splicing, Intercoastal installed the piles in 60-foot lengths. The telescopic mast on the Mobilram allowed the company to work easily with the long lengths.
The bottoms were vibrated in with an ABI MRVZ 1400VS vibratory hammer mounted on a TM 20/25. Because the bottoms were vibrated rather than pounded in, the tops required minimal preparation for splicing. "Another benefit of the Mobilram is that the same machine could be fitted with a Delmag impact hammer to proof test the piles," Burns added.
The Mobilram helped Intercoastal to maintain exceptionally good tolerances in the design location and orientation of the H piles, leading the project owner's engineers to use Intercoastal's work as an example of what can be done in terms of limited deviations, Burns said.
In areas where obstructions in the upper soils were not as common, engineers chose to use 2,700 18-inch diameter Monotube piles. The tapered bottom of the Monotube was vibrated to 37 feet and filled with concrete before a 40-foot top section was weld-spliced and driven on the concreted bottom with a mandrel.
Because the Monotubes have a unique fluted shape, a special jaw was designed so the Mobilram could vibrate the bottom in. The variable moment feature of the ABI MRZV 925 VS vibro mounted on a TM 13/16 was used to install the Monotube bottoms with little or no damage to the thin-wall top. Once concreted and spliced, the Monotube piles were bottom driven to 80 feet with Delmag D30 impact hammers mounted on the TM 20/25.
The project also required Intercoastal to install 600 drilled shafts. For this, the company used the TM 20/25 outfitted with an ABI double head drilling attachment to install 24-inch diameter shafts at high rates of productivity in tough drilling conditions, including shallow obstructions and dense soil. Under the watchful eye of the New York City Transit Authority, Intercoastal had to work with very tight tolerances on displacement of in-situ soil to avoid settlement or heave of the elevated subway line, which runs near the north property line, while installing the shafts.
"The real beauty is seeing the Mobilram used for all three kinds of piles on the same job," Burns noted. "There were economic advantages, scheduling advantages, engineering advantages, and innovation that led to quality improvements because of the improved deviations. You couldn't ask for more: Better quality, lower budget, better schedule and improved tolerances. It's hard to beat that." Burns estimated production with the Mobilram was "conservatively 25 percent better" than conventional methods. "I wouldn't entertain the idea of doing it any other way," he added. Additionally, he found the support offered by Hammer & Steel throughout the project to be invaluable. "They understand what we are up against, particularly when it comes to New York union labor rates," Burns said. "Hammer & Steel understands time is of the essence.