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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 #1, #2, and #3 qualify for <br />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 <br />pad will have a topsoil berm along the up-gradient perimeter that will direct runoff from undisturbed <br />areas azound the outside of the pad azea. The remaining perimeter, except for access en[ry, will have <br />an earthen berm and ditch to contain all runoff from a 10-yr/24-hr storm event. A two-foot high <br />berm will be constructed around the majority of the pad to control both surface water run-on and mn- <br />off The down gradient berm will be constructed along contour. <br />To ensure that the mh-off from a ]0-year, 24-hour event is contained, a containment ditch will be <br />constructed pazallel to the down gradient berm as shown on attached Figure 1, Typical Drill Pad. The <br />ditch will be approximately 2 feet deep with 1.SH:1V and 3H:1V side slopes and approximately 100 feet <br />long. The ditch will have adequate storage to contain the 10-yeaz, 24hour event (1.7 inches). The <br />runoff volume and ditch volume calculations are shown on the attached spreadsheet, <br />During regrading the earthen berm would be removed and the topsoil from the up-gradient berm <br />would be spread and left in a roughened condition to reduce the potential for erosion until <br />revegetation is accomplished. On these small areas it is believed that leaving the surface in a <br />roughened condition is sufficient sediment control. However, where the terrain is extreme or <br />conditions dictate, silt fencing will be installed in appropriate locations to further reduce the potential <br />for siltation off-site. <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 />• <br />10 <br />