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<br />J~~TEO STgJFS <br />z <br />. ~ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY ~ <br />2 ~ <br />~f ~,o~ REGION 8 <br />'~= ="0'4` 999 18T" STREET -SUITE 300 <br />DENVER, CO 80202-2466 <br />Phone 800-227-8917 <br />h11p:llwww.epa.govlre0ion08 <br />F~t~.;~ii/~~ <br />FEB 2 5 2004 FEB 2 ~ 1004 <br />Division of Minerals and Geology <br />Ref: 8P-W-GW <br />CERTIFIED MAIL <br />RETURN RECEIPT REQUESTED <br />Mr. Ed Baker, REM <br />Plant Manager <br />Natural Soda, lnc. <br />3200 County Rd. 31 <br />Rifle, CO 81650 <br />Re: A_paroval 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 />Dear 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 bentonite (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 maybe reached by calling (800) 227-8917, <br />extension 6211 and 6405 respectively. <br />w <br />~a Printed on Recycled Paper <br />Page 1 of 2 <br />