Monday, August 27, 2012

Aug 25, Bog Bridging on Mt Greylock

Saturday Aug 25th, Bog Bridge Install, North of Mt Greylock

We loaded up the truck from our materials storage area near the Mt Greylock Visitors Center.  We had about 40 pieces of lumber to carry in to the work site on the AT just north of the Bellows Pipe Trail junction.

Loaded up and ready to go.

Bog bridging (also known a puncheon) is used to carry hikers over intermittent wet or muddy areas along the Trail.  The goal is not to keep hikers feet clean, but to keep hikers from widening the footpath as they try and walk around wet and muddy areas.  If left un-bridged, these areas will just become wider and wider, creating increasing impacts on the adjacent vegetation. 

Whenever we can, we try and resolve the problem by improving the drainage, or installing large step stones, but this is not always possible in very we areas, or locations where water is collecting on top of bedrock.

Bog bridging lasts about 10 years and tends to stay on top of muddy areas, rather than sinking in.  In remote locations, we prefer to use native trees cut from the nearby forest.  However, this is time consuming, and eventually we will run out of suitable trees.   In most AT locations in Massachusetts, it is possible to use rot resistant rough sawn lumber from local saw mills.  Tamarack (also know as Larch) and Black Locust are preferred species, as they are modestly priced and are naturally resistant to decay.  This does mean that we need to carry in materials for most bog bridging work.
Don and Dave bring in some planks
Sim carries in a base timber

In some locations, we have used man-made materials such a Trex or similar products.  While they last a very long time, they are expensive, heavy, and look very unnatural in the back country.    We also try and avoid pressure treated lumber, as we hesitate to introduce poisons into the local environment.  We've also found that PT lumber can dry out and split in direct sunlight.

Dave and Sim replace some missing planks
On today's project, two sites were replacements of existing bog bridging where the planks had rotted off of the base timbers.  Four other sites received new bog bridging, as they are showing signs of widening.

Don and Greg set some step stones

At two other sites we added stepping stones leading on and off of an existing set of bog bridging.  This protects a slightly longer wet section not quite covered by the existing bridging.

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