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III IIIIIIIIIIIII III <br />Phi Cr ~ E <br />E~~ NECA <br />S Coa/Company Seneca Coal Company <br />March 11, 1997 <br />Mr. Jim Burnell <br />Division of Minerals and Geology <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203-2273 <br />~?ECEIVED <br />MAR 131997 <br />3;v,~,on ~~ ~~,~ne~a~s s Geolo9Y <br />RE: Yoast Mine Permit C-94-082, Haul Roads A and B Preliminary <br />As-Built Certification Addendum <br />Dear Mr. Burnell: <br />This is an addendum to the preliminary as-built certification for <br />Haul Roads A and B to the Yoast Mine that was submitted to the <br />Division on November 22, 1996. It was agreed upon by both the <br />Division and Seneca that this additional information be provided <br />until the final survey can be conducted which will generate the <br />as-built drawings and configurations for both haul roads. <br />Culverts & Drainage Ditches <br />Drainage control for both roads is provided by culverts and <br />ditches. All designed culverts have been installed and riprap has <br />been placed at the inlets and outlets for these structures. <br />Riprap lined channels are also used near several fill locations <br />to convey water to the culverts. Culverts YB-7 and YB-8 were not <br />installed since this portion of Haul Road "B" was not <br />constructed. Final as-built data for the culverts will be <br />provided in the final report, similar to the road as-built <br />certifications for the Seneca II-w Mine. Please refer to Exhibit <br />13-9, Typical Haul Road Details, for typical drainage structure <br />information and Attachment 13-7, Ditch Designs, for the two types <br />of ditch sections. <br />Cut and Fill Slopes <br />As is stated in the permit, road cut slopes are not steeper than <br />1v:1.5h, in unconsolidated material or 1v:0.25h in rock. <br />Embankment fill slopes are not steeper than lv:2h, except where <br />embankment material is a minimum 85 percent rock. Embankment <br />slopes will not be steeper than 1v:1.35h unless it has been <br />demonstrated to the Division that embankment stability will <br />result. The minimum safety factor for all embankments will be <br />1.25. A stability report entitled "Geotechnical Investigation <br />Haul Roads Y-A and Y-B and Sedimentation Pond 010" is located in <br />Attachment 13-5. This report concluded that all road cut and <br />fills will be stable. Attachment 13-6 "Engineering Geologic <br />Mapping, Yoast Mine and Vicinity" discusses the various road cuts <br />Seneca Coal Company • P.O. Drawer D • Hayden, Colorado 61639 <br />Telephone (970) 276-3707 • FAX (970) 276-3014 <br />