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Preliminary Adequacy Review <br />Bear Coal Co., Inc. - Bear Mine <br />Pa qe Five <br />2.05.4 Ponds, Impoundments and Diversions <br />1. Demonstrate how the statement that alteration of a natural drainage is "not <br />applicable" (page 62) while the plan labelled 2.04.3(2)(a)-1 shows a "permanent run- <br />off diversion" with riprap (page 23). A detailed design of the permanent diversion <br />by a professional engineer must be supplied. The structure must be designed for the <br />100-year, 24-hour event pursuant to 4.05.4(2)(b) and 4.05.4(4). The sharp right <br />angled turn in the diversion seems to compromise the intention of establishing a <br />natural post-mining configuration. The spoil pile North of the turn in the diversion <br />must be addressed if a modification of the plan is warranted. <br />2. Sediment control system: Due to the short expected life of mine, problems noted <br />regarding sediment control design will be waived if an adequate maintenance plan <br />is supplied. The applicant should note that the highest sediment yield will be <br />in the first phase of site reclamation. This may entail sediment removal more <br />than twice a year. <br />a. 4.05.6(3)(b) Sediment clean out: The statement that sediment will be removed <br />from the ponds on an annual basis will only be appropriate if the sediment volume <br />does not meet or exceed the pond's design capacity. A preferable maintenance <br />schedule would call for removal of sediment when the volume of sediment <br />accumulated equals some fraction of the design volume (say 600). This must be <br />continued throughout reclamation phase of the operation. Ths Division suggests <br />the placement of permanent markers in each of the sediment ponds at the elevation <br />of the cleanout volume. This will assist mine and inspection personnel in pro- <br />viding for maintenance when necessary. <br />b. 4.05.2(4)(e)(i) Culverts: On page 62 of the application, BCC states that <br />two 16 inch culverts convey undisturbed drainage under the road and to the <br />river. These culverts should be displayed on some mine area map, peak flows <br />for the 10-year, 29-hour event should be provided and calculations provided <br />to show that the culverts are adequate. <br />c. 4.05.6(4) Design Drawings: BCC has not provided detailed design drawings <br />of any of the sediment control structures. BCC must provide detailed design <br />drawings, including: <br />1) Embankment cross-sections showing: <br />I. Elevation of the 200% and cleanout sediment storage volumes. <br />II. Elevation of the principal and emergency spillways and dewatering <br />devices. <br />2) Cross-section drawings of principal and emergency spillways. <br />3) Certification that the drawings were done by or under the supervision <br />of a Certified Professional Engineer. <br />