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Section 816.46(q) Continued. <br />year, 24-hour precipitation event, <br />regulatory authority. <br />or a larger event specified by the <br />(2) The embankment shall be designed and constructed with a static safety <br />factor of at least 1.5, or a higher safety factor as designated by the <br />regulatory authority to ensure stability. <br />(3) Appropriate barriers shall be provided to control seepage along <br />conduits that extend through the embankment. <br />(4) The criteria of the Mine Safety and keaith Administration as <br />published in 30 CFR 17.216 shall be met. <br />Sedimentation Ponds A and D have storage volumes greater than 20 <br />. acre-feet, and the emergency spillways for these ponds have been <br />designed to safely discharge the 100-year, 24-hour event without <br />regard to the additional dewatering capacity provided by the <br />principal spillway (riser). This design consideration is <br />conservative, because the riser will operate during the 100-year, 24- <br />hour event and supplement the dewatering capacity of the emergency <br />spillway. <br />As documented in Exhibit 42, Drainage and Sediment Control Plan, a <br />static safety factor of over 1.5 is incorporated in the design. <br />Seepage barriers are designed and will be constructed around the <br />outlet conduit extending through the embankments. All criteria of 30 <br />CFR 71.216 are reflected in the design specifications. <br />(r) Each pond shall be designed and inspected during construction under <br />the supervision of, and certified after construction by, a registered <br />professional engineer. <br /> <br />816-58R <br />Revised - January, 1991 <br />