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activity. The information derived from this would then be used to determine if the current model American Soda has proposed (combination of TDR and mass balance calculations) is adequate enough going forwazd. What we propose is consistent with American Soda's own promise: "If a technology or method is found that has a high probability of success, it will be tested for application in American Soda's operation". 3-D Seismic must be a minimum requirement for commencing operations. The problem with the subsidence plan as it is currently written, "TDR is an accepted an effective method for monitoring subsurface subsidence in this type of application.", is that American Soda's method for extraction is unlike any other type of solution mining currently employed. Therefore, they can not conclude TDR is an accepted an effective method. Furthermore, TDR only tells the operator that subsidence has or has not occurred. It does not provide information on what the cavity looks like, whether or not the solution mining process is breaching an aquifer or whether or not the indication that subsidence has occurred also resulted in the commingling of aquifers. In short, TDR provides too little actual information. The TDR subsurface subsidence plan, coupled with information proposed in the present Groundwater and Surface Water Monitoring Plan, would make it difficult and even impossible to determine if American Soda was impacting the hydrogeological balance. If a breach of the aquifers is discovered by subsidence or by leakage of process fluids, the environmental damage would be too far gone to mitigate, leaving the public to face the costs associated with groundwater reclamation. We are continuing to give thought to the matters addressed in the Second Adequacy Letter, and may be corresponding with you further in that regard. Sincerely, J hn C. Ehmann ector of Operations