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STATE OF COLORADO RIC NnRD D. •.1. Gov crnm III III III III IIII III <br />DEPARTMENT OF NATURAL RESOURCES <br />D. Monte Pascoe, Executive Director <br />MINED LAND RECLAMATION <br />423 Centennial Building, 7313 Sherman Street <br />Denver, Colorado 80203 Tel. (303) 839-3567 <br />David C. Shelton <br />Director <br />March 3, 1981 <br />~ . <br />T0: Brian Munson j <br />`-" <br />FROM: Jim Pendleton ~~-^~= -~ ~- ---_ . <br />SUBJECT: Review of the Subside a and Underground Development Waste Geotechnical <br />Sections of th~e-i~7unger Mine Plan <br />Pursuant to your request I have completed a preliminary review of the subsidence <br />and waste disposal sections of the Munger Mine plan submitted by Sheridan <br />Enterprises. I forward the following comments for your consideration. <br />Subsidence: <br />Section 2.1.6 of the permanent program permit application includes the statement <br />that; "convergence data and observation of rib stabi]ity obtained to date during <br />exploration activities have shown no abnormal movement." The application should <br />include data to substantiate the applicants subjective judgment of normal move- <br />ment". Further, this section of the application states that, because the work <br />in this permit term (five years) will include only development work, which will <br />preclude subsidence, no subsidence monitoring is planned for this permit term. <br />This subjective opinion should also be better supported by data or literature <br />references within the application. Minor subsidence may occur and a properly <br />designed monument monitoring system could allow the collection of valuable rock <br />mechanics data which could be utilized in subsidence prediction for furture permit <br />operations. <br />Paragraph 2 of section 2.1.6 contains: the statement that; "...no structures or <br />renewable resource lands exist within the proposed permit and adjacent areas." <br />If you and Roy Cox concur with that statement, the applicant is correct in <br />presenting no further response to permanent regulatory program Rule 2.05.6(6). <br />Thought should be given, however, to whether projected future mining activity <br />could affect structures or renewable resource areas in an expanded permit area. <br />If the answer to this query is affirmative, the operator should anticipate <br />future information and conformance requirements with Rule 2.05.6(6). <br />Underground Development lJaste Disposal: <br />This permit application a]lows for the placement of development waste from the <br />McClane Canyon operations of Sheridan Enterprises within the Munger operation's <br />underground development waste disposal fill. I believe that this may require <br />specific variance to be grante~.Rules 2.05.3(6) and 4.09 appear to limit disposal <br />to within the specific permit area in which the waste is generated. <br />The second paragraph on page 2-31 of the application includes the statement that <br />the topography of the site of the disposal pile ranges from slopes of 1 vertical: <br />2 horizontal to 1 vertical: 1 horizontal. Rule 4.09.1(10) of the permanent <br />regulatory program requires that key-way cuts excavated to stable bedrock or rock <br />