Tom's Blog

Friday, December 18, 2009

Constructing a boardwalk

One of our major winter/spring projects is the construction of a boardwalk that will permit access across our wetland to the creek. The goal here is to have access to the wetland and creek, so that we can carry out restoration work on the wetland. At the same time, we will be able to monitor changes in the flora and fauna.

The boardwalk is being constructed in units that will lie atop 5-foot sections of used utility poles (donated by Madison Gas and Electric). Each unit of pressure-treated wood is 10 feet long and the deck boards are 3 feet long X 6 inches wide. The design, created by Jim Hess, is simple and easy for non-skilled workers to construct. All 20 units needed for the complete boardwalk have been constructed in the past two days.

The first photo shows the initial layout of a unit. The 10 foot long "stringers" standing on end are laid into spacer templates at both ends. These hold the stringers at the proper distance until the deck boards are attached.



The second photo shows the early stage in the installation of the deck boards. A thin spacer board is placed between each deck board, and another spacer is used on each side to ensure that the unit remains straight and true during construction. Self-threading screws are used, which penetrate the screw holes and into the side grain of the stringers. As the deck boards are fastened, the unit begins to take shape. When about half the deck boards are fastened, the templates are removed.








The third photo shows screw holes being drilled in the deck boards. These holes were found to be necessary to keep the deck boards from splitting.


The next photo shows a unit almost completed. We found that a second unit could be built on top of the first unit, up to a stack of six units. A simple design involving alternating light- and dark-colored boards is being created.


The final photos show several completed units, being stored outside in the snow. In addition to Susan, Marci, and Amanda (shown here), the construction crew included Jim Hess, Denny Connor, and Kathie and Tom Brock.


The boardwalk will be installed in the marsh as soon as conditions are suitable (absence of snow; hard surface). The units will be trucked to the starting point and laid end to end across the sedge meadow. Each unit will be fastened on each side to the next unit by two 2 foot connector pieces, using 1/2" bolts. The connection was designed so that the boardwalk units can shift, but the whole boardwalk will remain intact. Twenty units are needed to go from dry ground to the creek edge. A small bridge (already built) crosses a small, permanently flowing rivulet.

Installation of the boardwalk will require the help of a group of volunteers. Keep posted for further information.

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