The Big Dig at Mill Creek Central
The railroad is expanding up the big hill to the west of the main yard. The track will go along the side of the hill for about 400 feet to the north end of the property and then make a long loop back, continuing up grade through a 104 foot tunnel (the big dig) before arriving at the relatively flat meadow. The tunnel has been under construction since 2001 and is now (summer of 2006) nearing completion. The construction of the track from the main yard to the tunnel is underway and the tunnel should be in operation by fall 2006.
The railroad has another tunnel (shown on the right) which goes under the driveway. This tunnel was constructed by digging a trench and placing a 20 foot long 8 foot diameter filling station gasoline storage tank in the trench and then covering up the tank. Large holes were cut in the end of the tank making it a large pipe or tube.
The plan for the big dig was to use the same technique as for the tunnel under the driveway: dig a trench, lay in the tanks and then cover the trench.
At the beginning the backhoe made pretty quick work of the trenching with the truck hauling the dirt away.
Some of the dirt was used on the right-of-way leading to the tunnel and the remainder was used to build up abutments for a future trestle at the south end of the meadow.
Opps ----- we ran into sandstone and progress stopped. No problem, get out the jackhammers.
Man was that slow dirty work. Work stopped in the fall or 2001 as winter approached. During 2002 tanks were collected and thought was given to digging through the rock.
In 2003 a bigger shovel was brought in. The trench was made wider and somewhat deeper.
A concrete breaker was also tried on the rocks. It didn't do much good..
The bigger shovel made some progress but the deeper we went the harder the rock. We had to settle with the tunnel floor about 2 foot higher than initially planned. At least it won't settle.
The big digger also made moving the tanks easy.
The tanks were about 20 foot long. Each tank was cut in half so that the the sections could follow the 80 foot tunnel radius.
The tanks were aligned such that there was an end at each joint to strengthen the joint.
The right tool makes any job easy...... or at least easier.
The big equipment left after the tanks were in the trench. At this point another 20 or 30 feet of tanks were needed. Work progressed on the other tanks. The tank ends were cut out, the tanks abutted against each other and welded together. Because the tanks were joined at an angle there were gaps at the joints which had to be covered. This work was carried out in 2003 and 2004.
This is the north end in the summer of 2004. All that is needed is the cribbing around the entrance and a drainage pipe plus gravel in the tunnel bottom.
This is the south end in 2004. A couple more tank sections are needed.
Two additional 10 foot long tanks were obtained in 2005. These were 8.5 foot diameter oil field storage tanks. One was installed in 2005 and the last in early spring 2006. Photo at right shows the south end mid summer 2006. This completed the work on the tanks except for the cribbing around the portals and final back filling.
This is the view from the south portal mid summer 2006. There is a slight upgrade for about 50 feet and then the track is flat for several hundred feet across the meadow. A drainage pipe had just been installed on the up hill side of the roadbed. The pipe runs beside the roadbed for about 40 feet and then under the roadbed and down the hill on the left. Part of the pipe remains to be covered with gravel.
This is looking out of the north portal mid summer 2006. That track is awaiting installation. The stakes on the right are marked with the objective grade.
This is looking into the north portal mid summer 2006. Everything is ready for a final grading of the roadbed and laying the track. The cribbing around the portal and final backfilling will be done as time permits.
This is the inside of the tunnel . A perforated drainage pipe has been run down the center and the floor then covered with gravel.
Note that part of the tank ends have been left to increase the strength at the joints.
Update October 29, 2007: We finally got the track down through the tunnel in the spring of 2007. Later in the fall we installed the tunnel portals, built retaining walls and graded the area. See following photos.
Photo above shows the north entrance. Sure looks different from the earlier photos. Some final smoothing of the soil is required and then seeding to finish this end.
Photo at right is taken looking out of the south portal. A lot of the grading involved making sure that water drains while at the same time making the hill look like a scale
Photo above is of the south portal. The grade on the right is near final. The bank on the left needs to be cut back a bit and smoothed.
Photo at right shows view from the south portal. The track doesn't go off a cliff --- it curves to the right then across the meadow to the trestle.
A bit of final grading and seeding is all that is needed to finish this project. The area should be green by the middle of 2008.