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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />FAX: (303) 832-8106 <br />October 29, 2010 <br />Mr. Tom L. Adams <br />ExxonMobil ,// <br />P.O. Box 2567 <br />Houston, TX 77252-2567 <br />Re: ExxonMobil, Colony Oil Shale?roject, Permit No. <br />Technical Revision, TR-13. r/ <br />I- -- <br />Dear Mr. Adams: <br /> <br /> <br /> <br /> <br /> SAFETY <br />C;7-J\[ 20 Bill Ritter, Jr. <br />G <br /> overnor <br />?? James B. Martin <br />?? <br />C, 3 Executive Director <br /> <br />? ,c<,'SA3lq <br />ti.v7 G kS <br />?il3 Loretta E. Pineda <br />q <br />FF <br />;' and ..'V"-A?y Director <br />l l:ira: <br />V <br />M-1980-047, Second Adequacy Review <br />The Division of Reclamation, Mining and Safety (Division) reviewed ExxonMobil's response to the Preliminary <br />Adequacy Review for a 1] 2 Hard Rock, Metal Technical Revision for the Colony Oil Shale Project, File No. M- <br />1980-047. A few minor issues must be addressed before the revision can be approved. <br />1. Please provide an estimate of the volume of water that will be captured and discharged from the four (4) to <br />eight (8) proposed A-Groove drainage holes. <br />• Response adequate <br />2. Monitoring of the A-Groove aquifer immediately above the Mahogany zone is not included in the <br />monitoring program. The operator must protect and monitor aquifers above and below the <br />mining/experiment interval. Therefore an A-Groove monitoring well(s) shall be included in the monitoring <br />program. <br />• Response adequate. It is understood that the lack of water and the chance of downgradient water <br />quality degradation is minimal to nonexistent due to the water from the A-Groove aquifer exiting <br />above the Mahogany Marker at the face of the formation above the mine portals. <br />The section titled Ground and Surface Water Monitoring does not provide enough information about the <br />proposed ground water monitoring program. Please provide all required information described in Rule <br />3.1.7(7)(b) regarding the proposed groundwater monitoring program. <br />• Regarding Rule 3.1.7(7)(b)(iii), specifically the part about reporting sample results to the office. <br />The Division will require that the reporting frequency of sampling results to be provided quarterly <br />in order to frequently observe water quality and the seasonal fluctuation of water levels. <br />4. The proposed wellbore abandonment for non-cased drain holes is stated to be "as-is". The Division requires <br />all holes, cased or not, to be plugged and abandoned in accordance with the requirements set by the State of <br />Colorado Office of the State Engineer. Specifically, the operator shall follow the requirements of Rule <br />16.2.1 in the Rules and Regulations for Water Well Construction. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines <br />COLORADO <br />DIVISION O F <br />RECLAMATION <br />MINING