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• ATTACHMENT 1A <br />HYDROLOGIC DOCUMENTATION FOR SMALL AREA EXEMPTION <br />TYPICAL DRILL PAD <br />SCC has provided the following demonstration to show that drill pad sites #2, #3, #4, #8, #10, #12, #14, and <br />#16 qualify for Small Area Exemptions (SAE) under the requirements of Rule 4.05.2(3). <br />The typical drill pad for the exploration holes will be approximately 100 feet by 100 Feet. The active drill pad <br />will have a topsoil berm along the up-gradient perimeter that will direct runoff from undisturbed aeeas azound <br />the outside of the pad area. The remaining perimeter, except for access entry, will have an earthen berm and <br />ditch to contain all runoff from a 10-yr/24-hr storm event. A two-foot high berm will be constructed azound <br />the majority of the pad to control both surface water run-on and run-off The down gradient berm will be <br />constructed along contour. <br />To ensure that the run-off from a 10-yeaz, 24-hour event is contained, a containment ditch will be constmcted <br />parallel to the down gradient berm as shown on attached Figure 1, Typical Drill Pad. The ditch will be <br />approximately 2 feet deep with 1.SH:1V and 3H:1V side slopes and approximately 100 feet long. The ditch will <br />have adequate storage to contain the 10-yeaz, 24-hour event (].7 inches). The mnoff volume and ditch volume <br />calculations aze shown on the attached spreadsheet. <br />During regrading the earthen berm would be removed and the topsoil from the up-gradient berm would be <br />spread and left in a roughened condition to reduce the potential for erosion until revegetation is <br />• accomplished. On these small areas it is believed that leaving the surface in a roughened condition is <br />sufficient sediment control. However, where the terrain is extreme or conditions dictate, silt fencing will be <br />installed in appropriate locations to further reduce the potential for sHtauon off-sire. <br />SCC believes these sites qualify for SAE status for the following reasons: <br />1. The small amount of disturbance associated with each drill pad (0.2 acres), <br />2. The containment of mnoff during the active use of the pads, <br />3. The use of supplemental silt fencing (where needed) following reclamation, and <br />4. There will be no mixing of surface waters with dischazge from underground workings. <br />