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r , • <br /> <br />To emphasize how favorable geologic conditions at Amherstburg site are, Figure 35a <br />compares two horizontal stress profiles, for the proposed field at Amherstburg and for the <br />nearby Sandwich field that was abandoned after formation of a sinkhole. Analyses show <br />that some tension would occur in the shale stratum immediately above the 30 ft thick salt <br />layer within the unit D at Amherstburg. This tension, however, is much smaller compared <br />to the one predicted for the Sandwich field where the overburden essentially failed. <br />Figure 35b further clarifies that tension above the salt within Unit D at Amherstburg <br />develops after about 37 years into the life of the field (if it is completely undermined). In <br />this condition, the magnitude of tension would increase slowly, as Figure 356 suggests, <br />and this shale stratum may be damaged, probably after about 50 years into the life of the <br />field. However, it is highly unlikely that this damage would lead to some adverse <br />consequences as other strata above [he field exhibit not tension at that time. <br />Of particular importance here is that even after 100 years tension will not develop <br />immediately above the cavity roof, Figure 35a. In the analysis, [his result is predicated by <br />a 20 ft thick layer of salt that was assumed to be left in place in the process of solution <br />mining. This salt layer in the roof is very important and should be carefully guarded <br />during solution mining operation. <br />The information that I presented in this letter is entirely a part of the report in its present <br />form. Should you require a more detailed exposition of [his topic along the lines as I <br />discuss here, I would be happy to revise the report. <br />Sincerely, <br />Ph.D. P.Eng. <br /> <br />