Berm Slope Construction Puts a Green Face on Coal Mining
By using Neoloy® Tough-Cells for berm slope construction, soil structure was preserved, erosion reduced and the mine enjoyed an aesthetic facade.
Challenge
Environmental considerations in the development of the Zacatoza coal mine pit, near Piedras Negras, required the construction of a 12m high protective berm. The berm functions as a physical and aesthetic barrier between the open pit and the neighboring residential areas of the town. In addition to a visual barrier, the slope is landscaped with mixed vegetation to provide a green ‘face’ to the mining operations. The berm also aids in containing and controlling fugitive dust and erosion of sediment from the site.
The berm slope is very steep (45°), which required soil stabilization and erosion control, including drainage, particularly as the slope abuts an adjacent highway. Unidad Micare evaluated several soil protection solutions that could achieve their goals in a cost-effective manner.
Conventional Solutions
The height and steepness of the slope requires unique soil protection strategies. Earth retention walls are more expensive to construct, while hard armor surfaces negate a green landscape. Erosion mats and mulches with netting are unreliable, do not ensure subsurface soil stability and cannot be used alone. Grass turf is another conventional solution, but it is inappropriate and expensive in an arid environment and difficult to maintain, particularly when revegetation may take time to establish itself.
Neoloy Tough-Cell Solution
Small 330-10 cm high Neoloy Tough-Cells were chosen as the best available solution. Neoloy was anchored on the steep slope at the crest and downslope with iron j-bars. Local topsoil with gravel content was used for infill. 330-7.5 high Neoloy Tough-Cells with concrete infill were used at the foot of the slope to construct a drainage ditch for the road to handle excess stormwater.
Neoloy serves as a mechanical barrier that preserves the soil structure and minimizes the erosive impact of water and gravity. This prevents runoff erosion, sedimentation to local water bodies and loss of fines (air-borne dust) to preserve local environmental quality.
In addition the perforated Neoloy Tough-Cells are an excellent growth stratum for roots and plants. Landscaping improves the visual environment, providing additional dust control, while the plant and soil interlock help stabilize the soil