Laserfiche WebLink
will only be required if the plan has undergone significant changes. Modification of the <br />Water Monitoring Plan may also be required based on the results of on-going monitoring <br />or as appropriate, in consultation with other regulatory agencies. <br />(6`" Paragraph) The Permittee will monitor a network of 25 monitoring well completions <br />for the 0-S year mine panel. Some of the monitoring well completions are grouped <br />together as nested or co-located monitoring wells for the Uinta Formation, A-Groove, <br />B-Groove, and Dissolution Surface. The Upper Aquifer will be monitored at twelve (12) <br />locations, the Lower Aquifer will be monitored at nine (9) locations, and the Alluvial <br />Aquifer will be monitored at four (4) locations. <br />(7~" paragraph) ,The monitoring wells for the initial five (S) year panel are positioned <br />up-gradient, down-gradient, and cross-gradient of the mine panel. The monitoring well <br />layout for the Yankee Gulch lease site is shown in Appendix I, along with the well <br />summary of the Final Ground Water Monitoring Plan (dated December 23, 1999) as <br />presented in Table 1. <br />*** <br />(9`h paragraph) The permittee is required to establish surface subsidence monuments, <br />including the initial 24 (twenty four) wells, by the Subsidence Monitoring Plan. EPA <br />requires American Soda to submit this data in their fourth quarter reports. In order to <br />establish a clear link between the UIC Permit and the activities listed in the Fourth <br />Revision of the Subsidence Monitoring Plan dated December 23, 1999, EPA has adopted <br />this Plan as Appendix J of this Permit. This subsidence plan may be changed based on <br />the results of the monitoring data and the studies to be carried out regarding technology <br />to determine the shape of the cavities. Changes of the Subsidence Monitoring Plan will <br />be made by modifying Appendix J of the Permit. <br />1. Solution Mining Well Field Monitoring Program. <br />*** <br />(~ Cavity development shall be monitored to estimate cavity size. Because the <br />leached solution cavity will be a matrix of oil shale rather than a void, size and <br />shape must be determined by indirect methods and standard logging methods <br />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 <br />performed. Continuous monitoring of flow rates, temperature, and densities will <br />provide an ongoing material balance, which will allow the permittee to make <br />calculations of the mass of nahcolite extracted, this information will be submitted <br />quarterly to EPA. A combination of time domain reflectometry (TDR) and <br />borehole geophysical techniques shall be employed for determination of <br />subsurface movement and to ascertain movement of strata overlying the solution <br />cavities (see Section 3.0, Subsurface Monitoring, Subsidence Monitoring Plan, <br />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 <br />FINAL: Modification No. 9, UIC Area Permit No. CO30858-00000 <br />Page 4 of 46 <br />