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_,~. <br />i ~ <br />DEPARTMENT OF NATURAL RESOURCES <br />D Monlo Pascnr,. Ezec uii~r Uvrnor <br />MINED LAND RECLAMATION DI <br />DAVID C. SHELTON Director <br />R~ohartl D Lamm <br />Governor <br />T0: Mike Savage <br />FROM: Jim Pendleton <br />RE: Review of TBM <br />M E M O R A N D U M <br />(~tpt•i 1 1983 <br />~/tiJ,~~ . <br />to Stipulation #14, Permit #C-048-81 <br />Pursuant to your request, I have reviewed Trinidad Basin Mining's <br />response to Stipulation No. 14 of their current permanent program <br />permit. The company basically reiterates the information which was <br />presented in its original permit application. This is inadequate to <br />satisfy the stipulation placed upon permit approval. <br />The company presents calculations for total excavated pit volumes, <br />coal volumes extracted and the resultant excavated overburden volume <br />(total pit volume minus the extracted coal). The implicit assumptions <br />made by the company are, (1) that the post-mining topography achieved is <br />essentially identical to that of the original pre-mining topography, anc <br />(2) that all materials originally within the pits have been returned <br />during backfilling. The applicant has failed, however, to demonstrate <br />the validity of these basic assumptions. <br />The stipulation's third sentence reads; "This information shall <br />include discussion of previous pit volumes, pre- and post-mining <br />topography of previously mined areas, including proposed and existing <br />road configurations, ..." The purpose of this statement was to cause the <br />applicant to demonstrate the validity of their implict material balance <br />assumptions. <br />The applicant should complete a survey of the existing topographic <br />configuration of representative previously mined areas. By comparing <br />pre-mining and post-mining topographic mapping, the applicant should <br />demonstrate that all material movements have been taken into <br />consideration. Significant quantities of overburden which were <br />originally within the pits may now be residing in road embankments, <br />sediment pond embankments, stockpiles, etc. Until this uncertainty is <br />resolved, the applicant's implicit assumption (1) that the pre-mining and <br />post-mining topographies are identical, and (2) that all materials <br />originally within the pits have been backfilled cannot be verified. <br />cc: Brian Munson <br />Document No. 2140E <br />423 Centennial Building. 1313 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567 <br />