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the retort. In the absence of a rind, the inherently low permeability of the shale will <br />prevent the escape of products or contaminants from the mining interval. <br />b) The rind is expected to dissipate as the retort cools. The rind is not intended to be a <br />part of the long-term confinement of residual retort products. That isolation is performed <br />by the low permeability of the illite shale itself and the overlying saline mineral <br />formation layer. <br />c) The rind is not permanent, and there is no significant flow of groundwater in the RI <br />zone. <br />d) Contaminants produced by the retort in the RI zone are naturally confined as <br />explained in b). <br />e) No. The rind is caused by a traveling compressive wave at the boundary of the retort. <br />As the rind advances, the shale formerly in the rind will thermally fracture, and this <br />fracture permeability is what enables retort growth. <br />5. Is there any risk that thermomechanical fragmentation will result in intermingling <br />of the aquifers? <br />AMSO Response: <br />No. The Pilot Test will retort a limited volume of oil shale surrounding the well bore <br />within the RI zone. The retorted volume will exhibit an increase in porosity due to the <br />extraction of kerogen and some loss of mechanical strength due to thermal fragmentation. <br />Increased porosity and thermal fragmentation can be expected to alter the hydraulic <br />properties of the rock mass within the immediate vicinity of the well bore. AMSO's <br />current intent is to grow the retort volume to a diameter of up to 25 feet in 3 to 6 months. <br />No fragmentation-related impacts to the hydraulic properties of the rock mass are <br />expected beyond this diameter, thereby precluding the potential for intermingling of <br />aquifers located hundreds of feet above the R1 zone. AMSO will monitor the growth of <br />the retort volume by various geophysical techniques. <br />6 Will any water remain in the hole after retort? If so, will it be analyzed for <br />contaminants? <br />AMSO Response: <br />Only a very small amount of water could remain in the retort at the bottom of the heater <br />sump at the end of the Retort Test. As mentioned above, water flow is extremely slow <br />into wells drilled into the retorted zone, so we expect it would take years for the retort to <br />fill with water naturally. AMSO has no plans to sample after retorting. <br />7 In that the thermomechanical fragmentation causes the formation of a subsurface <br />void, is there any risk of subsidence? <br />AMSO Response: <br />AMSO's current intent is to grow retort volume to a diameter of up to 25 feet during the <br />Pilot Test. Retorting may or may not produce a subsurface void depending upon the <br />degree of thermal fragmentation, amount of kerogen extracted, shape of volume retorted, <br />in situ stress state, and thermo-mechanical properties of the oil shale. No void may occur <br />if retorting produces a porous, but stable, self-supporting "honeycomb" structure in the <br />oil shale. In the event that thermal fragmentation weakens the retorted oil shale to the <br />110 East 3`d Street. Suite 201 P.O. Box 1470, Rifle, CO 81650/phone•970-62514324 facsim0e•970-62511318 4