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Stipulation No. 15 BEFORE THE PERMANENT POND DESIGN CAN BE CONSIDERED ADEQUATE, THE APPLICANT MUST JUSTIFY THE USE OF A CURVE NUMBER OF 72. THIS MUST BE DONE WITHIN THIRTY (30) DAYS OF PERMIT ISSUANCE. The principal spillway will function as the dewatering device for this pond. It is a 12-inch diameter pipe situated above the maximum sediment level. The minimum retention time for ponds as established by the EPA is 24 hours. It is felt that the pond will dewater too rapidly to allow proper settling times with the proposed 12-inch diameter dewatering pipe. Therefore, the following stipulation is necessary. Stipulation No. 16 WITHIN THIRTY (30) DAYS OF PERMIT ISSUANCE, THE APPLICANT MUST PROVIDE THE DIVISION WITH POND OUTFLOW CALCULATIONS PROVING THAT THE 12-INCH DIAMETER PRINCIPAL SPILLWAY WILL NOT DEWATER THE MAJORITY OF WATER IN THE SEDIMENT POND BEFORE 24-HOURS FOLLOWING A DESIGN STORM. IF THESE CALCULATIONS SHOW AN INADEQUATE HOLDING TIME, THE PRINCIPAL SPILLWAY/DEWATERING DEVICE MUST BE REDESIGNED, AND RECONSTRUCTED WITHIN 60 DAYS OF PERMIT ISSUANCE. The peak flows calculated for the emergency spillway are incorrect, however, the spillway has adequate freeboard to pass these flows. The emergency spillway design is therefore adequate. The applicant does not plan on changing the existing pond and all designs are as built. Site inspections by the Division have shown that this pond is seeping either through the embankment or infiltrating through the bottom of the pond. The applicant has proposed monitoring the pond, however, the Division feels that the potential poor water quality of the pond may have detrimental effects downstream if the seepage continues. The Division stipulates the following. Stipulation No. 17 WITHIN THIRTY (30) DAYS OF PERMIT ISSUANCE, THE APPLICANT WILL SEAL THE POND WITH A NON-TOXIC BENTONITE SEAL TO PREVENT FUTURE INFILTRATION. Inflows to the pond include a discharge from abandoned underground mine workings. Past measurements have shown this discharge to exhibit low pH values. The applicant has proposed to "monitor this discharge and treat if necessary" by "adding lime to the pond or other measures". The Division requires the applicant to provide a detailed treatment plan for implementation if a low pH is detected.