Recent Projects

Columbia Gas Hill Slide

Marco Concrete Lifting was contacted by Columbia Gas Company to provide a solution for a hill slide issue they were having. A few years ago a gas line had exploded and caused the hill to slide. Because of the blast the earth received during the explosion, the rock strata on the hillside was disrupted, causing slippage.

This project is very important to ensure the stability of the broken strata located around the gas line as to help prevent any further explosions. We were able to provide Columbia Gas Company with a permanent solution that will help to ensure the safety of the slope as well as the gaslines from being disrupted any further. 

Our project location was on a very steep hillside near Poca River Road in Putnam County, WV. After discussing options with Columbia Gas company, we proposed to create a more environmentally friendly solution to the slippage problem.  By using rock fall netting held onto the hillside with rock anchors, all parties agreed that this method would be best because it would allow natural vegetation to grow back on the hillside versus installing an unsightly retaining wall.

Our primary concern was to attend to and secure the land movement of the two sections of pipeline as indicated by Columbia Gas Company. Our project covered one section on either side of pipeline and one section over the pipeline.

Sections on either side of pipeline were anchored on approximately 10′ centers down each side with staggered/split-spaced rows down the middle on approximately 10′ center. To complete this project we used only the best products in the industry. Geo Brugg 4mm Tecco Mesh rock fall netting along with Con-Tech Systems, Ltd. Titan 30/14 hollow bar anchors secured with grouting.

After clearing off the hillside of brush, stones, etc., we regraded the area. After the clearing work was complete we set the site up for the installation of our rock fall netting. To prepare to hang the Tecco Mesh on the hillside, we first marked off the pipeline areas as well as our locations that were to be drilled for anchor placement.

The drilling process begins by attaching a Titan 30 Cross-Cut, Carbide drill bit to a 30/14 Titan hollow bar anchor. Anchors are driven with a TEI 250 rock drill mounted on on our ZX-75 Ingersol Rand excavator. Because of the steep grade of the slope we had to attach our excavator with mounted drill rig to our Caterpillar D5 dozer to ensure the safety of our workers. We attached the dozer to the excavator via winch cable. Once safely connected to one another for stability the ZX-75 is lowered over the hill into place at the bottom. We work our way from bottom to top with the anchor drilling and installation process.

Once we begin drilling an anchor we drill down 25′ with compressed air. As anchors are placed firmly in the rock/hillside, we have our grouting team standing by on the top of the hillside. The grout men begin mixing Portland cement to water and sending it down to the drilled anchors by hoses. We fill the hollow anchors with the Portland cement grout mixture until rich grout is observed over topping the hole. Some of the anchors we drilled took up to 20 bags of pure Portland cement which is equal to 2,000 pounds!

We inject the earth with grout and the grout spreads out to fill any voids underground. It also provides us with a solid hillside to hold our anchors in place. The anchors are used to hold the rock fall netting and, together our anchors and mesh will hold the slope from any further damage.

After a seven day set (which is the industry standard), a torque test was taken on the first few anchors that were installed. The results were 500-600 foot pounds of torque. This project covered two separate areas of the hillside covering a total of 9,094 Square feet. We drilled 120 anchors varying in depth from 5′-25′ deep to provide us with our support for the Tecco Mesh.
After all grout is completely set-up, we bring in our state of the art Geo Brugg Tecco Mesh mounted to a Caterpillar excavator. This stuff is seriously heavy, weighing in at 845 Lbs. per roll. Each roll is (11′6”wide and 98′ long) and we had to carefully direct the mesh to the proper areas. Once in place, the mesh is unrolled and cautiously placed down slope.
We strategically drape the mesh over the anchors as we work our way down slope. Once each piece of mesh is installed properly on the face, we install a spike plate on each of the anchors. Next we tighten anchors to the spike plate with a spherical nut designed specifically for the spike plates and torque to full capacity. This step ensures that our mesh isn’t going anywhere and will continue to hold the hill from any further slippage.

We finish up the project by re-establishing water breaks in the slope and then re-veg with fertilizer, winter rye, grass seed and straw.  From start to finish the project took 21 days and because we followed a strict safety regime, we had no work related injuries. Success!