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-14- 5. Design velocity for Ditch D-3 must be reported as required under section 4.05.3(b)(a). 6. Design discharge for Ditch D-4 does not concur with peaks reported in the !•lash program. The design must include all calculations including slope adjust- ment and basin shape correction factor if SCS method is to be used. Please include raw calculations to verify compliance raith 4.05.3. The design velocity for this ditch is also required under section 4.05.3(6). 7.' Ditch D-5: Peak discharge calculations exhibit the same discrepancy as noted in No. 6 above. This discrepancy needs to be addressed. Design velocities also must be reported. 8. The application must justify the use of ponds,P-4 ,:, etc. and 6 instead of a continuous ditch. !dhat is the storage capacity of these ponds? If these ponds are permanent who will maintain the ponds after completion of mining? These detention ponds are considered under our regulations to be impoundments and therefore must comply with section 4.05.9 and the design criteria of U.S. Soil Conservation Public Standard 378, 'Ponds', October, 1978. Please consult these references for further details and requirements. 9. Design velocities for Ditch D-6, D-7, and D-8 must be reported. 10. Ditch D-9, and D-10 peak flow calculations do not indicate the use of a slope adjustment and basin shape correction factor. Peak flow calculations will not be approved riithout this adjustment. ?evised designs which include design velocities must be included. 11. Design velocities for Ditch D-11 and D-12 must be reported. 12. Please provide information on the existing pond, culvert, and ditch at the bend in the haul road above Ditch D-10. This diversion is essential to the proper operation of ,your refuse disposal drainage system. if the existing diversion were to breach or overflow, failure of Ditch D-10 and the sediment pond could occur. 13. It appears that all cuvverts were designed with an allowable head water. The application rwst include culvert profiles to verify that this design head water will be available. The application must also address embankment erosion and fill saturation. 4!h en computing head ~•iater requirements for all culverts, the culvert rating form used should be referenced to allor•~ the Division to cross check the calculation. The application should also distinguish between inlet and outlet controlled culverts. 14. The manning's 'n' value, type of culvert, and entrance loss coefficients used in the designs of culverts must be included in the application. This infor- mation was only included for culvert C-6. 'rJe need this information for all culverts. 15. The Division requires the !MASH and FLDROT computer printouts used in the design of the sediment control plan. The application should also reference the source of the ;•JASH and FLDR07 program manual.