Round Lake is located just north of Albany, New York, and is connected to the Hudson River by the Anthony Kill. Almost a decade ago, a former hunting camp on the lake’s western shore was on the verge of being turned into a residential subdivision when the Town of Malta (where the land is located) and local conservation groups stepped in to purchase the 20-acre waterfront parcel and development rights to land surrounding the camp. Last fall, the Round Lake Preserve – a 90-acre wildlife sanctuary that is the culmination of a 10-year effort by various persons, organizations and governmental agencies to preserve recreational open space for current and future generations – finally opened to the public.
A key feature in the Preserve is a handicap-accessible boardwalk, which leads through wetlands and terminates in a boat launch. From the launch, one can paddle a canoe or a kayak (no motors allowed) back and forth in the serpentine flow of the Anthony Kill upstream to Round Lake or downstream to the Hudson River several miles away. Our construction firm was hired as a subcontractor to build the 300-ft. long x 8-ft. wide boardwalk.
Helical Pile Foundation
Working from a set of plans prepared by the LA Group, a landscape architecture and engineering firm in nearby Saratoga Springs, we began construction of the boardwalk in the autumn of 2014. Because the boardwalk would be built through sensitive wetlands, we had to take extra measures to minimize our impact on the environment during construction.
Helical piles were specified in the design, for example. They’re commonly used on wetland projects because of their minimal environmental impact compared to concrete piers or other foundation systems. They were installed by Techno Metal Post of Albany (technometalpostny.com).
Initially, their crew was able to move their auger equipment into position over wood mats placed on the ground. But as work progressed into the wetlands and the water became too deep to utilize the mats, the crew built a floating work platform. Unfortunately, that system proved to be inefficient because the water was not deep enough and the work platform would get stuck in the mud. In addition, when the platform was floating, it was difficult to keep it positioned to accurately locate the helical piles.
Even so, the crew hurried as best they could through the shortening days of October and November to beat the oncoming cold weather. But the winter of 2014-15 came early and hard, freezing the water quickly and creating a sheet of ice that effectively locked the platform in place and halted work.
While the cold never let up, this proved to be a blessing in disguise as the crew could now work on top of the frozen water. By the time spring came and the ice melted, we were left with a nice foundation system on which to build, albeit with high water. While we knew the water level would recede as warm weather returned, the brackets that received the header beams were barely above the water line when we began framing the boardwalk.
When the factory-direct shipment from the pressure treater arrived on site, we staged the lumber for efficient access by sequencing the stacks in the order that they would be needed. Of particular help was the fact that our local supplier, Curtis Lumber, provided a fork lift for unloading the approximately 25,000-board feet of 2x12 framing lumber and 5/4 x 6 decking as part of the purchase agreement.
The project specifications called for KDAT (kiln-dried after treatment) ACQ-treated #2 SYP lumber. Because kiln-drying minimizes shrinkage and may even minimize warping, it’s probably a good choice for decking and railings – areas with full exposure to the sun. However, I think it might be a waste of money to use KDAT lumber for beams and joists that are shaded by the deck above.
In fact, my local Simpson Strong-Tie representative reminded me that while kiln-dried lumber won’t shrink much, it typically will swell when placed in service and exposed to moisture. As it expands and places stresses on the fasteners, he noted that he’d seen some cases where deck screws had failed in shear. As an insurance policy against screw failures associated with KDAT lumber, we upgraded from the coated #8 screws specified in the plans to #10 deck screws.
When we started framing, we found that the KDAT lumber was slightly wider than its nominal 1 ½-inch thickness, enough so that the four PT 2-bys used to build the beams would not fit into the 6 1/8-inch wide U-shaped brackets on top of the helical piles. So we had to cut 1/8-inch deep mortises at the ends of each beam to fit the beam into the hardware. A router made short work of the problem.
In order to provide access as we proceeded into the wetland, we used long aluminum planks, and installed decking as we framed. We also used landscape mats and plywood on top of the wood framing as a temporary walkway, and set up a picnic tent for sun protection and to keep the saw dry during showers.
We supplied electricity to the remote site with a 6 kW gas generator, positioning it in front of our work trailer and away from where we were working to reduce noise levels. We also found that by propping up sheets of plywood around – but not too close to – the unit, we were able to further reduce sound pollution from the generator. It took our crew of two or three guys (depending on the day) about 6 weeks to complete the boardwalk and boat launch. In the process, we used over 15,000 deck screws to fasten the decking to the frame. While this upgrade added to our costs, we did not ask to be reimbursed (this was a public bid, fixed price project). The cost was minimal and an example of the small give-and-take between contractor and design professional that we’ve learned can help make a difficult project like this successful. And simple measures – like providing weather protection and muffling the noisy generator - increased production and made the work environment more comfortable for the crew – a win/win for everybody.
Darren Tracy PE is the owner of West Branch Engineering & Consulting, in Saratoga Springs, New York.