One of our clients has a 65.6 ft (20 m) tall mechanically supported earth (MSE) wall (to dump the ore from the mine into the crushers). The wall is about 984.25 ft (300 m) long and has approximately 30-degree slopes on both ends, like a pyramid. These slopes have eroded over the last 8 years of operation and some of the wall reinforcing is exposed. We want to stop the erosion and stabilize the slopes. The instructions issued to the contractor are: level the slopes; fill the voids; compact; apply shotcrete (maximum 1 in. [25 mm]). The area in question is 6.6 x 65.6 x 131.2 ft (2 x 20 x 40 m). Is shotcrete application in this case appropriate? Can you forward information on experts we could consult on?

Shotcrete is well suited to the application you have described. You need to determine the characteristics that you want from the shotcrete (strength, toughness, freeze-thaw durability) and include these in the specification. The 1 in. (25 mm) seems very thin for a long-term installation. Please be aware that the material costs (in most cases) will be a small part of the total cost of the installation. You should also make sure that you have a good specification for surface preparation. If the existing surface is not properly prepared, the added shotcrete will not bond well and the installation will not last very long.

The ASA Online Buyers Guide (www.Shotcrete/BuyersGuide) is an excellent source to locate members within the field of shotcrete whom are listed as shotcrete consultants.