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1985 '/z SOUTH BROADWAY <br />GRAND JUNCTION, CO 81507 -9649 <br />DAUB & ASSOCIATES INC. - 1X' _... (970) 254 -1224 <br />° r ;ems %y ►'a <br />FAX (970) 242 -8438 <br />email: gjdaub @daubandassociates.com <br />www.daubandassociates.com <br />April 29, 2014 <br />, <br />Division of Reclamation, Mining and Safety <br />Attn: Minerals Division MQ <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />Re: Response to DRMS' Second Adequacy Review - Request for Additional <br />Information Regarding Technical Revision 35 to M1983 -194: Natural Soda, <br />Inc. Drilling Activity - Subsidence <br />This Natural Soda, Inc. (NSI) submission is in response to a DRMS request for <br />information regarding TR -35, regarding subsidence monitoring, the proximity of <br />proposed production wells to previously mined intervals, and a review of TR -35 <br />reclamation cost estimate. The DRMS request for additional information was contained <br />within the DRMS Second Adequacy Review of TR -35 application, dated April 24, 2014 <br />and signed by Mr. Travis Marshall of the Grand Junction DRMS office. NSI's response <br />to two requests for clarification and a request to review the TR -35 reclamation cost <br />estimate follow: <br />1) What measures will be implemented to measure the potential subsidence <br />above the proposed cavities? <br />Monitoring for potential subsidence above NSI's proposed production cavities consists <br />of surface and subsurface subsidence monitoring. Surface subsidence monitoring <br />involves the installation and monitoring of surface subsidence monuments (SSMs) <br />above the proposed mining interval. Subsurface subsidence monitoring is achieved <br />through the construction and monitoring of subsidence monitor wells (SMWs) near the <br />proposed cavity. A new SSM will be installed for the 14H well pair, and the existing <br />SMW (DS -5) will be used for subsurface subsidence monitoring. Existing SSMs will be <br />used to monitor the 8H and 9H cavities. Subsurface 5uksiden:;e for the 89-' and 9H will <br />be monitored by the DS -7 well (to be drilled 2014), and the preexisting 4A -5M well and <br />3M -TDR well. The 4A -5M well bore is abandoned, but the cables still function and are <br />still monitored. <br />2) Due to the proposed production well pairs being located within close <br />proximity to previously mined zones will the potential for subsidence be <br />magnified? <br />None has occurred to date and none is anticipated. <br />SPECIALIZING IN PROFESSIONAL GEOLOGICAL, ENVIRONMENTAL, HYDROLOGICAL, GEOTECHNICAL AND PERMITTING SERVICES <br />