On the way to Bear Spring: a butterfly finds something interesting on Big Tree Jr.
The Bear Spring crew had an ambitious "to do" list for Saturday. On the way to Bear Spring, Dave W., one of the club's certified sawyers, was going to get a first-hand look at Big Tree Jr. The sawyers are planning how to get BT Jr. off the trail in the safest way possible and Dave's mission was to provide an assessment to add information that will figure into the sawyer's final 'plan of action'. Once at Bear Spring, there were two projects on the trail, one above the switchback just south of the spring and one just below the switchback and running past the spring itself.
Here is the problem above the switchback and the one we tackled first:
As you can see, we had a serious wash-out problem on the AT that had progressed to mini-gully status from all the heavy rains we've been having over the last couple of months. This problem was created by tree debris piled along the tread edge which created a berm that kept water in the trail. The solution was two-fold: get a waterbar in as high as we could to get water off the trail as soon as possible and restore the tread from a 'U' shape to an almost level tread with a slight outslope (after removing the debris berm). A tread with a slight outslope allows water to flow off the trail at many points rather than running down the trail, all the while gaining volume and velocity that has enough power to scour dirt off the tread. We restored the AT in two phases to a condition that was very similar to the original sidehill when the trail was constructed.
Project #1 - Tread repair:
David single-handedly takes out the largest offending log with a rock bar (and here I'd been thinking we might need a chainsaw!)
The depth of the built-up dirt and leaf debris that had washed up against the log berm .... from the bottom of the pick head to the bottom of the first yellow paint band. The obvious leaf debris was fire-raked off and the next layer of decomposed leaf matter as well, until the actual dirt was exposed.
The compacted dirt had to be 'pick axed' loose and moved back up into the tread. While doing this, a large rock partially above tread level was determined to be in the way and had to be removed.
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The inside "angle of repose" slope had slumped down into the tread and also had to be repaired. Whenever you either dig new sidehill or repair old sidehill, you always remove leaf matter and 'duff' to get down to the mineral soil before digging. This debris is raked way on down the hill to prevent it from acting as a berm and trapping water. These pictures show the leaf matter removed and the inside 'angle' clean and ready for digging/restoration.
Meanwhile, back at the waterbar:
Dave has marked where the trench will be for the waterbar rocks and has started excavating.
Probably the biggest issue of the day was finding suitable rocks - the immediate area had one decent rock and all the rest had to be moved a good way down the trail to the waterbar site. Here is rock #1, in place.
Rock #2 ready to go in place as soon as the trench is the proper depth.
Looking like a waterbar! All that is needed is a rock to complete the 'runout' which makes sure the water goes totally off tread and doesn't creep back around the lower edge.
Here comes that last 'runout' rock ..... looks like a big one!
What is going on? Rocks #2 & 3 are back out of the waterbar! It turned out that the runout rock had some nice tread/step edges as well as being large and heavy. After some mulling-it-over time, it was decided the runout rock would be a better #2 rock, #2 would become #3 and the new runout rock would be the former #3. The switches were made ..... not easy, but the waterbar was constructed the 'best/right way' for the rocks that were available.
The final result for Project #1 - a beautiful waterbar that should be easy for hikers to navigate while keeping water off the tread. The tread itself has been restored ..... 40 feet of it! That is the original 'Big Tree' in the distance, marking the location of the switchback above Bear Spring.
This is another washout problem which is pretty bad, although it has not started to 'gully' yet. You can see the top layer of dirt on the tread has washed off, exposing rocks and a large root. The trail visible going off to the left is the trail to Bear Spring.
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About the time the guys were setting the last rock on the waterbar and starting to dig out the water runoff ditch to complete that project, the tread repair was also finished up. A big thunder storm was rumbling and it was becoming obvious it was going to catch us on the mountain. There was no time to put in a waterbar on the lower section ....... but maybe there was a temporary solution. Initially, the thought was to put a 'grade dip' sort of structure where we would be ditching for a rock waterbar, just to get water off the trail since heavy rain was obviously on the way. In moving debris off the side of the trail above the switchback (that log wasn't the only thing that had to be removed), a pile of large limbs was moved and one of them was just the right size to span the tread exactly where a waterbar was needed. A 15-minute waterbar was put in to divert water until we can get back up to Bear Spring for permanent waterbar number two.
A temporary solution to a bad water erosion problem.
By this time, the storm was all but overhead and lightning was starting to crack around us. We had fixed one of two wash-out problems at Bear Spring and Mother Nature washed us out as well on our trip off the mountain in some wicked weather. It was an 'exciting' end to a day that saw one interesting project completed, which should be of great benefit to the structural integrity of the trail and give hikers better footing on that section of AT. We'll be back at Bear Spring in the near future to finish up the second project by installing a permanent lower section water erosion control structure, removing that big old root in the trail and maybe working with the spring sign placement as well.
(Photos and video: Merlot)
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