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Mining Plan proportions than is the case today. Today it is a small scale structural problem, but in the early 1970's, as will be discussed later, it was a huge problem that, in effect, was allowing most of the mountainside to simply fall apart in pieces as large as city blocks. That problem is no longer there and cannot recur because of Castle Concrete's continued mining. This is because the structural feature that was allowing the mountainside to slowly collapse has been removed by mining most of the remaining limestone. In general, the method of mining is to select an area for extraction, drill the site to a predetermined depth, partially fill the holes with explosive, and blast the rock. The drilling pattern and amount of charge largely determines the dimensions of the resulting rocks. Some control over the kind of product to be produced is achieved by varying these factors. As will be explained, when the final topographic configuration is approached a different procedure will be used in the future that will produce greater control over the amount of reclaimable land, allow the final bench to be more easily reclaimed, and help alleviate the small scale structural problem produced by the dip of the limestone bed itself. The result will be good production from the resource and far more reclaimable land than has been produced in the past. • Bench Production and Clwracteristics.• The key to producing more reclaimable benches is to reclaim the bench before the next bench down the slope is created. In the past, the next bench was created before any reclamation was attempted. This resulted in the previous bench being almost inaccessible for reclamation and only limited amounts of growth could be produced, as is the case today on most of the older benches. A second aspect of producing more reclaimable benches is to determine the required width of the step before it is created. Rather than using a set figure for step width, the width should be determined with a view toward the final topography needed for that area. This requires some preplanning. On the following page is presented the Bench Geometry Model that will be used to calculate appropriate step width based upon the fmal topography wanted and the height of the backwalls to be produced. First, the final average slope desired needs to be determined for the particular area to be mined. Then, the horizontal and vertical distance of the total slope is measured. These values can be measured from the mining and the reclamation plan maps. By using various backwall heights and plugging the measured values into the formulas an average step width can be calculated. This average is the value that should be sought during the mining. • The model allows for variations produced by non-vertical backwalls. Geometry model Pikeview Quarry Amendment Exhibit D Page 11