Rockin' It In The Rain (Sec 10)

A saddleback caterpillar at the Humpback Rocks Visitor Center

On Friday, the Weather Channel was predicting an 80% chance of precipitation on the mountain Saturday with a chance of thunderstorms. It didn’t sound good, but knowing that conditions on our section are really unpredictable, we made backup arrangements at Sherando for the planned picnic and confirmed that all would go as we planned on Thursday. Saturday morning I double-checked the forecast and noted that they were only predicting a 10-30% chance of rain before 1 pm with worsening weather afterwards. 

Up on the mountain in dense fog and a light drizzle, we split into four crews and made the decision to send the picnic crew down to Sherando. My crew was headed to Section 10 to put in some waterbars and consider a cribbing project that we had identified on the August work trip. We grabbed two rockbars, three pick mattocks, a shovel, a Pulaski, and a pair of loppers for the five person crew before driving over to Dripping Rock. 

Once on the Trail, we reconsidered the erosion problem and decided that a pair of check steps followed by a waterbar would be the best solution to the gullying that was occurring, since there was no easy way to direct water off the Trail near the top. Unlike waterbars that are designed to deflect the water off the Trail, check steps are designed to dam up the water and slow it down. The slower water deposits sediment above the step and helps restore trail that has been eroded into a gully.

 

 Mark digs the trench for a check step

Mark chops a root in the trench with the step rock ready to go as Bill looks on

The lower check step went in fairly easily, using the perfect rock that we had unearthed on the last work trip. The upper check step was a bit more troublesome. Only six to eight inches below the surface, we ran into a slab that prevented us from placing the step exactly where we wanted it. Some exploratory digging revealed the outline of the slab and the space that a step rock of the right size could fit in. The rock we had wanted to use was definitely too large, so we took the measurements and went on a rock hunt. 

 The first (lower) check step in place

Hunting for the right rocks can be one of the most frustrating parts of rock projects. Rocks in the same small area often have the same shape and general size. Sometimes there seems to be nothing but football-shaped rocks, with convex faces on both sides that are extremely hard to place securely in the ground. In other areas, rocks of any sort are just not to be found. My technique is to take a large pick mattock and probe under the leaves with the pick in areas that seem to have some exposed rock with the right general features. Ideally, I’ll find the rock above the work site so that it can be easily moved downhill. I hesitate to accept the first rock that might work, but continue looking in case the perfect rock shows up. Often that rock isn’t right at the surface, but is hidden by leaves or a little soil and duff.

 

 Theresa searches for a bedrock free location for a second check step

We did manage to find a set of rocks that fit the required measurements. We set the main rock to create a 6-8 inch step from the downhill side while providing a solid tread surface on top. We buried a full 2/3 of the rock and locked it in with small wedge-shaped rocks. Then we added a pair of rocks to capture and retain water on the sides. Finally we placed a series of large rocks on both sides of the step in a natural pattern to discourage people from walking around the step.

 

 Dave works on the second step

The second check step from below

And from above

While this second step was being completed, a rock waterbar was installed lower down to direct any water off the trail that had made it over the check steps. Large narrow rocks were buried deep in the trail in a shingle pattern, leaving only a small portion exposed to form the backbone of a dirt trough and berm structure that will shunt any water off the trail. 

Project three completed - a waterbar (there's a fair bit of rock under that dirt!)

Just as we were finishing up, the rain began to intensify, so we decided to leave the crib project for another day and hauled our muddy tools out to the road. We rinsed off the tools at Dripping Rock and, after putting them away in the shed, headed down to Sherando for warm dry clothes and good food at the picnic. Not a bad day’s work for a rainy Saturday!

Many thanks to Dave W., Theresa D., Dave G. Mark F. & Bill F.

 for making a great deal of progress on the Section 10 erosion issues .....

 despite the rain!

 

 ♦ ♦ ♦

(Photos & narrative: Dave W.)