Sunday, August 17, 2014

Good Old Fashioned Trail Work

Side Hill and Cribbing in Cheshire MA
June 10, 2014

Still working through the backlog of 2014 projects.  In June we set about correcting some treadway issues on the Trail between Rt 8 and the open fields south of Outlook Ave.

In one location we had a muddy section of trail that was oozing its way down hill, and in another nearby area the treadway was on the side slope of a small hill, but hiker traffic was slowly causing it to drift downwards as they looked for a level area to walk on.  While gravity was the culprit in both cases, we addressed them in two different ways.

Jim and Jim place rocks in the crib wall
In the muddy area, we harvested local stone to create a crib--a short wall parallel to the trail that is filled in with soil to create a level area that juts out from the slope of the hillside.

This requires a base row of rocks that sits below the surface of the hillside, upon which subsequent rows are stacked--each row set back from the one before.  This "batter" tilts the wall towards the trail, resisting the force of the soil packed behind it.  As the wall gets higher, mineral soil (dirt harvested from the adjacent woods and taken from below the top layers of organic matter) is laid in behind and packed down.  This soil should actually end up a little higher than the crib, and slope slightly out so water runs off over the crib, rather than flowing down the footpath.  Crib walls can also be constructed out of locally harvested tree trunks, held into the hillside with long stakes.
Crib is visible just past the white blaze

Interestingly, while we were looking for rocks, we found an old spring a few feet from the trail.  A rock wall had been built to keep the spring clear of dirt and debris running down the hillside and into the small pool.  The wall was likely constructed in the late 1800's when this area was agricultural land.  We cleared out the pool of accumulated debris, and now it's available for hikers to refill with water before heading up towards Mt Greylock.

Meanwhile, a 1/4 mile south in a drier area, the rest of our team worked to carve out the side of the hill to provide a level treadway.  Instead of installing cribbing, we cut a "full bench" shelf into the hillside creating a level area resting on undisturbed soil to provide a solid base for the trail.
Side hill trail being cut into the slope
This entails digging away a fairly large amount of soil, which is tossed down the slope well clear of the eventual footpath.  The downhill side of the trail should be at the edge of the slope of the hillside, while the uphill side is cut into the hill.  The new treadway is sloped slightly out, again so water will flow off of the trail, rather than down it.

Construction nearly complete, crew chats with an early thru-hiker
Constructing trail this way--more across the slope rather than steeply up the slope--makes for trail that will be stable, require little in the way of waterbars or similar structures and is resistant to erosion by runoff.  To route trails across slopes does require a fairly wide corridor, and works best where soils are deep and well drained.  It's not often in New England that we have these conditions, so this was a great opportunity to introduce this type of trail building to our volunteers.

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