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in a letter report dated January 12, 1993. A copy of the letter report, <br />including the certification statement is also presented in Appendix 12-1A. <br />HGTI, as part of the property title and permit transfer process, completed a <br />survey of the pond in 1992. A certified, as-built drawing, based on HGTI's <br />survey data, is presented in Exhibit 12-3, Truck Loop Pondl Existing Condition. <br />A SEDCAD 4 modeling demonstration shows that the Truck Loop Pond, in the <br />current configuration, contains sufficient storage capacity to treat the 10- <br />year, 24-hour storm event, as well as safely pass runoff from the 25-year, 24- <br />hour storm event. The SEDCAD 4 demonstration is presented in Appendix 12-18, <br />Pond Capacity Demonstrations. <br />Rail Loop Pond <br />As noted above, the Rail Loop Pond mss also constructed by the facilities <br />previous owner, H-G Coal Company in 1980. The outlet structure was modified in <br />late-1985/early-1986 to meat the requirements of Rule 4.05.5(7) . An existing <br />culvert spillway was replaced with a trapezoidal spillway constructed of <br />fabriform. A certification report, dated April 1986, stating the pond was <br />constructed in accordance with initial design and applicable CM LRD regulations <br />is presented in Appendix 12-LA, Pond Certifications. A second certification <br />report was prepared in September 1986, which certified the pond had sufficient <br />storage, at that time, to treat runoff from the 25-year, 24-hour storm event. <br />During preparation of RN-O1, HGTI determined the existing pond storage <br />capacity, based on a 1992 survey conducted by HGTI, was slightly less than the <br />original design capacity presented in Permit C-80-003. Consequently, HGTI <br />evaluated the pond configuration to determine that the pond met the <br />requirements of CDMG's sedimentation pond regulations. A technical revision <br />(TR-03) application was submitted to CDMG in 1997, which used SEDCAD +3 <br />modeling to demonstrate there was adequate storage to treat the runoff from a <br />10-year, 24-hour storm event. In addition, TR-03 presented a design to raise <br />the embankment a minimum of 0.5 feet to assure there was sufficient freeboard <br />in accordance with Rule 4.05.9 (7)(d). The embankment construction was <br />completed in 1998. <br />The as-built pond draining is presented in Exhibit 12-4, Rail Loop Pond2 <br />Existing Condition. The draining is based on survey data collected by HGTI in <br />June 1998, and verified in April 2005. <br /> <br />TR-06 12-1.2 Revisetl OS/OS <br />