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