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yINIVG ?LnN <br />• <br />all that will be needed. However, in most instances, such control will be <br />incomplete and some run-off will escape from the pit area and flow down the <br />washes. It is this run-off which will be controlled by the second measure. <br />Control of run-off within the washes, whether the site is mined for gravel or <br />not, is a necessity. In those washes where control does exist in the form of fair <br />sized stock ponds, the erosional damages are greatly reduced when compared to the <br />large washes where no stockponds exist and the water is allowed to freely flow <br />down the valley. In the free-flowing wash areas erosion channels as deep as 15 <br />feet and more can be seen. These channels are steep sloped and in places take on <br />the appearance of a developing badlands. 'this is due to the presence of the <br />Pierre Shale which erodes in this fashion when exposed on hillsides. <br />FYom these observations, it is clear that the control of water, particularly <br />• <br />in those areas where there is no current control, will be required. This control <br />will take place through the use of small catchments and dams along the water <br />courses below the operations. <br />Of course, this action will serve other purposes as well. It will help to <br />control the erosion in these areas so they can be more easily developed after the <br />operation is completed. <br />TIMETAffi.E ~ MINING PLAN: Determining the timetable for extraction of an <br />operation of this type and size is a difficult process at best. There are so many <br />variables which can alter the timetable drastically, trying to anticipate these <br />variations is virtually impossible <br />However, some crude estimates can be <br />provided. <br />Based upon the anticipated volume of gravel (a speculative projection in its <br />own right) and reasonable demand projections, it is estimated the operation will <br />last approximately 90 years. Therefore, each phase would occupy about 8 years of <br />• page 7 of 10 Exhibit D <br />