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I ??nss ? <br />American Shale Oil, LLC <br />MAR 0 3 2010 <br />n o eclamadon, <br />February 18, 2010 Mining and Safety <br />Ms Wendy Cheung / <br />US EPA Region 8 <br />8P-W-GW <br />1595 Wynkoop Street <br />Denver, CO 80202-1129 <br />-Dear Ms Cheung: <br />$ A <br />FEB 2 32010 / <br />GMPAM <br />a C 1 Cr <br />Replies to EPA Questions of February 2 <br />Further to our meeting of 0 February, please find attached a partial reply to the questions of <br />Sarah Bahrman, sent to us on 2`d February concerning our UIC permit application, submitted <br />in September 2009. The remaining questions require some analysis that is still in progress. <br />We hope to submit these last replies by end February. To assist you with our application, we <br />have also outlined below the methodology that we have applied in our design so as to protect <br />the aquifers. <br />One of the main attributes of AMSO's pilot oil shale retort is protection of the aquifers. Unlike <br />other research projects, our pilot test retort is located in the Illite Oil Shale below the nahcolitic <br />oil shale formation that is below all the aquifers. Our well design sets and cements a 9 5/8" <br />casing about 175 feet below the aquifer system. The pilot test retort interval is below this <br />casing point. The 175 foot section is the main barrier preventing any retort products or <br />injected fluids from reaching and contaminating the aquifers. Our geologic and hydrologic <br />exploration activity over the last several years has determined that this barrier provides strong <br />isolation protecting the aquifers. <br />Our approach has been to determine the risks to the integrity of this protective formation <br />barrier and 9 5/8° cemented casing, take measures to mitigate this risk and then design ways <br />of monitoring that the confinement works during the operation of the pilot test. The primary <br />risks identified are: <br />a) Integrity of the cement bond <br />b) Integrity of the casing <br />c) Integrity of the formation from the cement shoe to the aquifers <br />The integrity of the cement bond will be maintained by using a special high temperature <br />cement blend. This type of cement exists commercially, and the chosen cement slurry will be <br />tested prior to cementing to ensure that it will sustain the anticipated temperatures. After <br />cementing, pressure testing and cement bond log will be used to ensure that there is <br />satisfactory cement placement and bonding. Remedial action will be taken if necessary. <br />For the integrity of the casing, there are two risks identified, namely 1) collapse of the casing <br />near to the shoe due to the expansion of the formation with heating, and 2) the internal <br />corrosion of the casing. The mitigation for the collapse of the casing is to use three 30 foot <br />110 East 3' Street. Suite 201 P.O. Box 1470• Rifle CO 81650 970-625-4324 phone 970.625-4318 facsimile