While most mining facility managers focus their attention primarily on the processing ponds used for mineral and ore recovery, the collection and transportation ditches connecting the ponds together are just as important. Failing to design the ditches with care will only result in erosion, loss of flow, processing issues, and expensive repairs. Ditches are less expensive to install and maintain than closed pipes in most systems, but there may be some situations in which pipes are preferable or even required.
Connecting the Pad and the Ponds
The drainage ditches connecting the leaching pad with the processing ponds are the most sensitive parts of the transfer system. With direct and constant contact with the most corrosive and reactive chemical mixture, these ditches experience the most wear and tear. They’re also prone to filling up with sludge and reducing in volume and flow over time. If only some of the ditches will be lined with a geomembrane, rather than concrete or a clay liner, concentrate the polymer materials in the first few hundred feet of the drainage ditches to make the most of your materials.
Lining the Ditches and Trenches
The entire processing system will function best if all of the ditches are lined; from the leaching pad all the way to the return pumps for reusing the barren solution. Without liners, it’s all too easy for ditches to fall prey to erosion and bank collapse. Even if the banks of the ditches are kept shallowly graded to purposely prevent collapses, erosion causes silt to accumulate over time. Lined ditches won’t grow more shallow due to silt infiltration over time which slows flow rates, although they will still need cleaning to control solution carried sludge.
Preventing Debris and Blockages
Lined ditches may not have problems with silt and soil eroding off of the banks and into the channel, but silt can still accumulate from runoff entering from the wider area. Blockages also occur when branches, leaves, and other debris fall into the ditch and reduce water flow. Other waste begins to accumulate on the first piece of debris, quickly leading to a complete blockage that stops pregnant solution from reaching the processing ponds. Blockages also create the risk of overflow that leaves you at risk for environmental damage. Silt screens are a good method for preventing volume loss, but they won’t control trash and tree debris. Manual inspection, and removal, is the standard technique for keeping blockages under control at most ore processing facilities.
Bird Protection Netting
If your processing ponds qualify for bird protection netting to keep waterfowl from drinking or bathing in the solution, the ditches may need the same cover as well. Yet, trying to cover multiple linear miles of interconnected ditches can seem nearly impossible. This is one case in which adding some piping to the system in place of open ditches may reduce the work required for maintenance. Combining closed pipes or culverts with open ditches lowers the amount of space in need of bird netting, making it a more achievable goal for the entire facility.
There’s no reason to choose a different flexible liner material just for your collection and drainage ditches. The same tough liner you choose for your processing ponds and leach pad base will work well for the ditches as well. BTL Liners has all the materials you need for preventing seepage in your ponds and ditches, regardless of the type of mining solution you’re handling.
