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(2„a Paragraph) The applicant has prepared the Subsidence Monitoring Plan dated April, 1999, <br />which was submitted to the BLM, Colorado Division of Minerals and Geology (CDMG) and the <br />EPA. The 4th revision of this plan, dated December 23, 1999, is incorporated into this Permit as <br />Appendix I. As provided in this plan, the permittee must establish surface monitoring <br />monuments on the initia125 wells in addition to the grid of land surface monuments. The <br />subsurface monitoring plan includes the installation of coaxial cable in solution mining well <br />bores for use of Time Domain Reflectometry (TDR), which. is technology used to detect <br />differential movement close to the top of the cavity and above. If subsurface movement occurs, <br />the coaxial cable will break or stretch. The location of the change in coaxial cable properties <br />will be determined by use of a cable tester. Borehole geophysical logs will also be run <br />periodically to substantiate the TDR monitoring results, and corrective action implemented if <br />necessary. The shape of the cavity is, of course, an important element that affects subsidence. <br />For that reason, the permittee is required to undertake studies and evaluate techniques for <br />assessing cavity shape. Depending on the results of these studies, American Soda may be <br />required to establish additional monitoring wells to better track cavity influence on the pillars. <br />*** <br />(4`h Paragraph) The injection fluid and production fluid pipelines shall be equipped with <br />sampling ports to facilitate periodic collection of samples for chemical analysis. Injection fluid <br />samples shall be collected from the pipeline immediately upstream of where the pipeline <br />branches to feed all solution mining wells. Production fluid shall be sampled on the production <br />trunk pipeline prior to entering the steam stripper. Samples of both the production and the <br />injection fluid shall be collected and analyzed (for WQ2 Parameters, Table 3), according to <br />Section 4.0 Process Monitoring of the Ground Water Surface Water and Process Monitoring <br />Plan dated December 23, 1999, prepared by Agapito Associates, Inc. (the Water Monitoring <br />Plan). <br />(S`h paragraph) Monitoring of water quality and water level (see Section 2.0 of the Water <br />Monitoring Plan) shall occur at least once per month for monitoring wells located in the mine <br />panel. The monitoring wells listed in the Plan shall be monitored as provided in Section 5.0. <br />Five (S) quarters of additional data shall be collected prior to the commencement of operations. <br />The permittee must collect this additional baseline data for the Alluvial Aquifer, the Upper <br />Aquifer (A-Groove and Uinta Formation), and the Lower Aquifer (B-Groove and Dissolution <br />Surface). Additional monitoring wells may be deleted or added to the monitoring program, if <br />necessary, as development of the commercial solution mining well field progresses, or as <br />warranted by monitoring results. This will be done by modifying the Water Monitoring Plan. <br />*** <br />C. WELL OPERATION <br />**~ <br />3. Injection Zone. The injection zone is required to be a minimum of 1 SO feet below <br />the Dissolution Surface. The bottom of the injection interval will be <br />approximately 800 feet below the Dissolution Surface. The proposed injection <br />zone (approximately I, SSO feet to 2,200 feet in depth at a surface elevation of <br />about 6,230 feet M.S.L.) is outside of and isolated from the major aquifer systems: <br />FINAL: Modification No. 9, UIC Area Permit No. C030858-00000 <br />Page 2 of 45 <br />