Laserfiche WebLink
This does present a fairly constant overburden thickness ranging from approximately 15 to 100 feet, <br />which lends itself to area surface mining. The relatively high angle of dip on the coal seam and <br />surface requires some modification of what would be considered a conventional area mining pii <br />progression. This modification will be detailed later in this section. <br />A general description of the engineering techniques utilized in the development of an area surface mine <br />must begin with the exploratory phase. After the initial discovery of a potential coal field has been <br />made (generally by drilling several "wildcat" test holesl, engineers and geologists, utilizing available <br />maps and information, will establish an exploratory drilling program to "prove up" the coal reserves. <br />The drill hole pattern is determined and is normally based on some convenient breakdown of the public <br />land survey system. Additional drilling is conducted where the coal is expected to outcrop or where <br />faulted conditions are expected. The engineers then direct survey crews to establish baseline control <br />in order to locate the drill holes and property corners. With this survey control available, the area of <br />interest can be contour mapped from aerial photography. With an accurate base map and all of the <br />necessary drilling information, the engineers can calculate the various factors necessary to establish a <br />mining plan. In area surface mining, these factors would include acres of coal available, tons of <br />recoverable coal expected, cubic yards of overburden to be removed, and the ratio of cubic yards of <br />overburden removed per ton of coal produced. These factors and others are examined in the light of • <br />prevailing market conditions and a determination made as to the potential economic viability of a mine. <br />Once a positive determination is made and an annual output established for the mine, the engineers <br />are required to determine the size, type, and numbers of equipment or facilities needed, including <br />topsoil removal equipment, primary stripping machines, drills, tractors, loaders, haulage equipment, <br />reclamation equipment, coal handling facilities, and service facilities. Standard mine engineering <br />practices, including the examination of contour maps, borings, range diagrams, and manufacturer's <br />specifications, are utilized in sizing the major stripping machines. Quantities of soils to be moved las <br />determined by soil surveys) and the distances and travel conditions involved are used to determine <br />fleet type and size for topsoil handling equipment. Overburden borings, indicating type and amount of <br />rock, as well as expected production rates are examined in sizing blasthole drills and pit tractors. <br />Quantities of coal and rate of production are the major determining factors in sizing loaders and <br />haulage <br /> <br />2 <br />