Draglines Explained: Dragline Operations in Bradford & Union County
As previously highlighted, HPS plans to operate two draglines, one in Bradford County and the other in Union County. After the mining sites are prepared (e.g., establishment of the perimeter ditch and berm, vegetation clearing, and topsoil and overburden removal), the draglines will be used to excavate phosphate matrix.
What is a dragline?
A dragline is a heavy piece of equipment, resembling a large excavator, used in a variety of settings, including civil engineering, surface mining, and excavating. Draglines come in a variety of sizes, ranging anywhere from 5 to 10 to even 35-ton models. The bucket of the dragline also comes in a variety of capacities.
Bucket capacity for standard models can be anywhere from 50 to 90 cubic meters, but smaller models can be as small as 10 to 30 cubic meters and the largest models up to 120 cubic meters. Due to their large size, draglines are typically shipped in multiple pieces and then assembled on site. This is the procedure HPS will follow.
A dragline is operated by a large excavator that uses the dragline to pull a bucket by a wire cable. Using a series of cables, chains, and ropes powered by an electric motor, the bucket gets lowered down to the ground and is drawn using the cable so that the bucket drags and scoops up the material to be excavated. This process largely resembles using a crane. After the bucket is full, it is lifted and emptied.
Moving a dragline
It typically takes some time to move draglines, especially when moving a dragline a long distance. Due to the size of the dragline, it moves at a relatively slow pace. The size and weight of the particular dragline will usually determine the rate at which it can be relocated. Typically, to move a dragline, it is loaded on to a platform that will transport it along a path that has been cleared.
Impact of the draglines
HPS proposes a plan that will specifically avoid the majority of the undisturbed natural stream and creek systems and their riparian corridors. The very few exceptions to this involve threeproposed dragline crossings. The draglines will need to cross over Fivemile Creek, Richard Creek, and one unnamed stream;however, there will be no dragline crossing over the New River. These crossings will be temporary and result in no permanent impacts.
To eliminate and reduce the potential for downstream impacts that can be associated with a crossing, HPS plans to implement erosion and sedimentation best management practices before any crossing construction. HPS will also provide sufficient construction access for the equipment to avoid any rutting from vehicular traffic. Additionally, HPS will monitor the avoided streams as well downstream of the crossings to confirm adjacent mining activities do not cause water quality impacts.