- October 27th, 2014
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Update 20141030: Terrain image from Google Maps Engine. Highlighted area shows the approximate area of the North Basin discussed below.
As most Silver Comet Trail cyclists know, it has been a problem keeping the mud and water out of the Brushy Mtn train tunnel. When we started our clean-up efforts the tunnel was flooded with mud and water. When I began my work at the tunnel, one of my first projects, I investigated the source of the runoff at the east end of the tunnel. Since the tunnel is cut into the rock of the mountain it is a long hike from the trail to the areas near the tunnel entrances, so I decided to start from the road above the tunnel. You can read about that here.
I found that a large area of many acres drained into a basin, North of the East entrance to the tunnel. The water that was flooding the east end the tunnel was coming from a hole in the wall of a natural basin (perhaps a sink hole). Over the last few years I’ve been thinking how best to control the water and sediment that is carried down and filling the water retention pond. I tried silt fences, this did slow the water, but not effective at eliminating the erosion of the 150 ft long channel that feeds into the the tunnel “cut” from this “natural” dam.
This Friday I attempted to create a solution. Leonard, the guy that works for Jim Brannon came out to help. We dropped the bulk of our gear from Brush Mtn Rd at at point that we hoped would be near the basin. Then drove the trail, parked East of the tunnel and hiked to the the work location. After some searching (I had made a good guess for the drop point) we located the dropped gear at the west rim of the basin. Our first chore was to clean out debris and the existing silt fence. Our plan was good, I brought a post-hole-digger to help “open the channel” under bank where the water flowed. Leonard from the basin side, me from the channel side, we dug from both sides. The bank was about 15-16 ft wide, wider than I remembered. I was skeptical that we would be successful. I worked for 1/2 hour and was able to get the 10 ft section of 4″ drain line through up to my shoulder. That was amazing. Leonard could see the end! We attached the 50 ft section of drain line and attempted to “snake” it through. Our first attempt me pushing and Leonard coaxing from the opposite side, failed. The ten ft section came loose, but it was close. After some work Leonard could see the end of the drain line. He manged to grab it with post-hole-digger and pull it through. Eureka, we had manged to get the 4 inch drain line through this 15 ft earth chasm!
Now we began the process of attempting to seal the chasm around the drain line. I brought thick foam, which we packed in around the drain line. Then silt fence fabric, rock on top of that. Wish we had more rock, but rock was scarce in this area. Then dirt, another layer of silt fence fabric, sticks and branches to hold that, then lots of dirt.
Fortunately, the bank over the area where we were working was soft dirt. Leonard worked really hard piling in more dirt. Then a layer of plastic screen and more dirt.
We covered the dirt with a layer of leaves and branches to help hold the leaves in place. Hopefully, this will control the rain water and eliminate most of the sediment that fills the retention pond. The next phase is to add an additional 100 ft of drainline and this will complete the 150 ft run to carry the water to the trail cut and eliminate the heavy sedimentation from erosional processes.