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G~-4 <br />,a~~n sT„~ <br />3 ~ U <br />~,z <br />Pam,,..,. <br />UNITED STATES <br />ENVIRONMENTAL PROTECTION AGENCY <br />REGION 8' <br />999 78'" STREET -SUITE 300 <br />'DENVER, CO 80202-2488 <br />Phone 800.227.89!7 <br />http:llwww.e pa.govlregton OB <br />11~~j~~ Y i~® <br />FEB 2 5 2004 FEB 2 7 2004 f <br />Division of Minerals end Geology <br />Ref: 8P-W-GW <br />CERTIFIED MAIL ~Ry <br />RETURN RECEIPT REQUESTED .L <br />Mr. Ed Baker, REM Yl'1 I ~ g 7' I ~ 7 <br />.Plant Manager <br />/0: Natural Soda, Inc. <br />3200 County Rd. 31 <br />Rifle, CO 81650 <br />7p~.. ~p.r~C <br />Re: Approval of Plan to Cement <br />Subsidence Monitoring We113M-~ <br />TDR: Natural Soda Inc. Solution <br />Mine EPA UIC Area Permit # <br />C030358-00000; Sodium Lease # C- <br />0118327, Rio Blanco County, CO. <br />Deaz Mr. Baker: <br />We received your letter of February 18, 2004, requesting an approval of your plan for <br />cementing the subsidence monitoring well # 3M-TDR.. The cementing is required to shut off an <br />8 - 15 gallons per minute flow in the well annulus downward from the perched, A-Groove, and <br />B-Groove aquifers into the Dissolution Surface aquifer. <br />After reviewing your letter and the attached plan, we are approving your plan. The plan <br />calls for injecting 30 barrels of food grade oil mixed with bentbnite (11 pounds per gallon) <br />through the perforations in the 4-1/2 inch casing. This will be followed by an enriched cement <br />mixture (15 pounds per gallon). If this attempt fails a sodium silicate/cement option will be <br />utilized. As a last resort, a hot mix of cement plus an accelerant will be utilized. Please notify <br />Nathan Wiser or Ken Phillips in the UIC Technical Enforcement Program of the final results of <br />this cementing effort. Mr. Wiser and Mr. Phillips may be reached by calling (800) 227-8917, <br />extension 6211 and 6405 respectively. <br />rr <br />~~ Printed on Recycled Paper <br />Page 1 of 2 <br />