2008-05-01_REVISION - M1973007SG (5)

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MINING PLAN For these reasons, the operator must have considerable flexibility with respect to where extraction actually occurs at any one time. That flexibility is needed to match the needs of the market place with the grades of sand produced. In short, access to both finer sand grades in the upper levels of the deposit and more coarse sand grades deeper in the deposit needs to be available at all times. To address this need, an approach is used that initially determines the final topography required and the general approach to creating that topography while avoiding a need to dictate in the design exactly where mining will occur at any one time. In effect, the final topography required and the stability issues needed for certain areas determine the general constraints on the mining process. So long as the final design topography is produced and proper stability for sensitive areas achieved, the actual process for extraction should be left up to the operator. The primary[mining constrain`-tinvolves stability of final slopes south of the highway,within the ditch corridor, and below the location of the ditch. In these areas it is vital that creation of final slopes using a backfill approach be avoided or kept to a very low amount. Clearly, some backfilling will be required to create these final slopes, but this backfilling should be kept to a superficial amount. That is, entire Popes show of be created by backfilling where the stability of the highway corridor or ditch could be affected by a slope failure. This is important because sand has a low capability to be compacted and until covered with dense vegetation is subject to intense gully erosion and, under special circumstances, large scale slumping. Severe gullying could cut back into the highway or undermine the ditch. Although cutting into the highway corridor is serious, undermining the ditch causing it to break could be disastrous and result in severe flooding before the water could be blocked off at its entrance into the ditch on Fountain Creek several miles to the west. Slumping of sand slopes can occur in primarily two circumstances. Although normal rainfall or even fairly heavy rainfall is not likely to cause a slump due to the low water holding capacity of sand, if the rain is heavy enough it can cause severe slumpage and slope failure. More often slope failure due to slumping is caused by animal burrows that essentially act as storm sewers directing runoff deep into the sand and saturating it from the inside out. It appears though that this is mainly a problem where the burrow entrances are on nearly flat land adjacent to a slope. If the burrows are on the sloped land they will not collect as much water,but, once again, if the rainfall is sufficient it can still happen. For the most part,the latter situation will be found in this area. West of Academy Boulevard, the former situation(burrows on flat ground) caused slumpage of the slope. But another major factor involved in those failures was an improper drainage from the roof of a Southpoint Plaza building adjacent to the slope. The design called for exiting the roof water into the parking lot on the other side of the building. But when the shopping center was built the water was drained from the back of the building next to the slope as well as on to the land where the Daniels Sand Pit Amendment (2008) Exhibit D Page 21 of 28