Laserfiche WebLink
r <br />aquifer zones at different well locations was undertaken and monitoring results reported. These <br />data provided no indications of leakage from test cavities. Pressure has been maintained <br />throughout Experimental Test Mine operations and no unexplained differences between injection <br />and production fluid flow rates have occurred. <br />As a result of the review of all comments and the available information, EPA has <br />been unable to substantiate the concerns that a:torsions have taken place. Therefore, no <br />changes were made to the Permit in response to these comments. <br />Comment 9: Advanced technologv is needed to monitor caviri shape and growth. <br />The following five (5) pazaphrased comments discussed issues and concerns relating to the <br />need for a more sophisticated technology for monitoring cavity shape: <br />1. The technology of monitoring the growth of a cavity is the most important step to prevent <br />adverse envirorunental impacts. <br />2. American Soda should be forced to use some type of technology to show them cavity shape. <br />3. American Soda is going to use mass balance to determine the size of the cavity. What they've <br />said in the BLM's DEIS is that technologies currently don't exist to tell you what that well is <br />going to look like. And, that is where the problem is going to be developed. <br />4. The solution mining cavity shape must be determined. <br />S.The method of identifying the shape of the cavity, which is critical to structural integrity, is not <br />described. Some method of monitoring the migration of the solution front into pillazs via the <br />saline beds is needed. <br />Response: Section 3.3 of the Subsidence Monitoring Plan, which has been incorporated into the <br />Final Permit (See appendix I), requires the operator to evaluate technologies to characterize <br />solution cavity size and shape and present their findings to both the EPA and the BLM by June <br />2000. EPA will utilize the information collected during the evaluation of cavity shape <br />technologies to determine if the Subsidence Monitoring Plan needs modification. If deemed <br />necessary, EPA may require the drilling of pillaz monitoring wells or some other measure, such as <br />additional monitoring wells. <br />The plan also calls for application of the selected technology(s) during the initial stages of <br />commercial mining when cavities in the first mining panel have reached an anticipated radius of <br />approximately 100 feet. The field testing results for the selected technology(s) must be reported <br />to EPA, and will be used to determine if monitoring or operational or monitoring requirements <br />need to be modified. If the size and shape of the test mine cavity is considerably different than <br />that modeled by the proponent to evaluate subsidence, EPA can then require additional modeling <br />or operational changes to solution mining processes if needed. <br />As indicated in the response to Comment 6, EPA is concerned about the shape of <br />27 <br />