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Part II, D, Monitoring, 9th paragraph (last paragraph before II, D, (1)) is proposed to be <br />changed as follows: <br />Current laneuaee: <br />The Permittee is required to establish surface subsidence monuments, including the initia124 (twenty- <br />four) wells, by the Subsidence Monitoring Plan. EPA requires American Soda to submit this data in <br />their fourth quarter reports. In order to establish a clear link between the UIC Permit and the activities <br />listed in the Fourth Revision of the Subsidence Monitoring Plan dated December 23, 1999, EPA has <br />adopted this Plan as Appendix J of this Permit. This subsidence plan may be changed based on the <br />results of the monitoring data and the studies to be carried out regarding technology to determine the <br />shape of the cavities. Changes of the Subsidence Monitoring Plan will be made by modifying Appendix <br />J of the Permit. <br />Proposed lan8uaee: <br />In order to establish a clear link between the UIC Permit and the activities listed in the Subsidence <br />Monitoring Plan (revised as of August 2004), EPA has adopted this Plan as Appendix J of this <br />Permit {replacing the original December 23, 1999 document). The permittee shall establish <br />surface subsidence monuments, including some located on some wells and well pads, as specified <br />in the Subsidence Monitoring Plan, Appendix J. American Soda shall submit this data in their <br />fourth quarter reports. This subsidence plan maybe changed based on the results of the <br />monitoring data and the studies carried out to determine the shape of the cavities. Changes of the <br />Subsidence Monitoring Plan will be made by modifying Appendix: J of the Permit. <br />• Part II, D (1) (f) is proposed to be changed as follows: <br />Current lanQUaee: <br />Cavity development shall be monitored to estimate cavity size. Because the leached solution cavity will <br />be a matrix of oil shale rather than a void, size and shape must be determined by indirect methods and <br />standazd logging methods used in mining operations will not be accurate. Material balances of the <br />volumetric fluid flow rates into and out of the solution mining cavities shall be performed. Continuous <br />monitoring of flow rates, temperature, and densities will provide an ongoing material balance, which <br />will allow the permittee to make calculations of the mass of nahcolite extracted, this information will be <br />submitted quarterly to EPA. A combination of time domain reflectometry (TDR) and borehole <br />geophysical techniques shall be employed for determination of subsurface movement and to ascertain <br />movement of strata overlying the solution cavities (see Section 3.0, Subsurface Monitoring, Subsidence <br />Monitoring Plan, Appendix J). The performance of the TDR monitoring will determine how TDR is <br />incorporated into the long-range monitoring program. If TDR proves to not be an adequate means of <br />monitoring subsurface movement, other instrumentation techniques shall be evaluated by the Permittee, <br />and if changes aze significant EPA will be notified as specified by Section III, E.10. TDR will be <br />collected monthly for each well in service and reported quarterly. <br />A subsidence report shall be submitted to the EPA annually. The report will contain data from surface <br />monument measurements, time domain reflectometry (TDR) data, and borehole geophysical data. The <br />annual subsidence report shall also include a map of surface monument locations, locations of wells <br />where TDR and borehole geophysics were conducted, a list of monument and well coordinates, and a <br />summary of pertinent observations during the reporting period. <br />Draft Addendum to SOB For Modification No. 9, UIC Area Permit No. CO30858-00000 Page s oj27 <br />