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• <br />Tab 13 <br />C~ <br />38. Seneca has revised the model for Pond 10 using a curve <br />number of 91 for pit disturbance areas, including <br />topsoil stripped, pit, and spoil areas. This curve <br />number was mutually agreed upon by SCC and the <br />Division. <br />39. Seneca has revised the model for Pond 11 using a curve <br />number of 91 for pit disturbance areas in accordance <br />with the comments of Item 38. <br />40. This comment addresses the concerns of the Division <br />with regard to the performance of an existing road <br />culvert downstream from the outlet of Pond 11. The <br />Division requested SCC to provide information to <br />demonstrate that the existing .culvert will handle any <br />increases in flow generated by mining activity. The <br />Rockcastle Road is an unmaintained and very limited use <br />road. The main traffic along this road is from oil <br />well personnel, employees of Bogle Farms, and hunters <br />to gain access to State lands. <br />A field survey of the conditions existing downstream <br />from Pond 11 along Rockcastle Road was conducted by <br />Michael Altavilla, SCC. The first culvert downstream <br />from Pond 11 is a 20-foot long, 18-inch CMP. It is <br />approximately 1150 feet from the proposed outlet of <br />Pond 10. This culvert is under a jeep trail which <br />heads to the northwest off Rockcastle Road. The second <br />culvert is 2400 feet from Pond 11 outlet. This 15-inch <br />CMP is 50 feet long and lays underneath Rockcastle <br />Road. A V-ditch runs parallel to and on the north side <br />of Rockcastle Road. The ditch averaged between 10 to <br />12 feet in width at the top and had a depth range of 2 <br />to 4 feet. The conditions of both culverts showed <br />partially plugged and crushed inlets and outlets. <br />Please refer to a copy of Exhibit 13-3 at the end of <br />the comment section showing the previously described <br />conditions. <br />Also included at the end of the comment section are <br />several SEDCAD+ and Dodson outputs for the vegetated <br />ditch and two culverts along Rockcastle Road. There <br />are several drainages including where Pond 11 will be <br />located that carry runoff to these culverts. The <br />outflow from a 10-year, 24-hour storm for Pond 11 was <br />calculated to be 3.21 cfs. The three designs provided <br />for these structures utilized a design discharge of 5.0 <br />cfs. All outputs show the existing conditions will <br />handle any flows created during the period of mining <br />activity. After mining and reclamation activities are <br />completed, because these disturbances are some distance <br />3 <br />