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~~ J"'t~n srgT~s ~ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY ~~ ~ REGION 8 499 18'" STREET -SUITE 300 ~~ DENVER, CO 80202-2466 ~~ http:llwww.epagovlregion08 _ TT~~. h~~L' J I __~~~ _- I i Ref: 8ENF-U"FO CERTIFIED MAIL 7003-2260-0001-7778-9333 RETURN RECEIPT REOLTESTED Mr. Ed Cooley American Soda. LLP 2717 Counrv Road 21 ~ Pazachute. CO 8163 Re: Underground Injection Control (UIC) TDR Subsidence Monitoring Neil 20-13 EPA Permit ~ C030358-04>j2 Rio Blanco County. Colorado Deaz Mr. Cooley: EPA's UIC program staff have reviewed your July 28, 2004, letter in which you included three measurement events using the 7/8 inch Time Domain ReYlectometry (TDR) subsidence monitoring cable installed inside the 2-7/3 inch tubing, now cemented to the 7 inch Long string casing in the above described well. The TDR cable was putposeiully crimped at every other tubing joint (about 60 feet). A total of 1404 feet of tubing was installed in the well. On June 17, 2004, the 2-7/8 inch tubing was cemented to the 7 inch long string casing. The tubing was lefr open for future temperature logging. The monitoring events referenced in your Letter are re-typed here for clarity. Event 1: June 17, 2004 -prior to cementing the 2-7/8 inch tubing in the 7 inch long string casing, Event 2: June 17, 2004 -immediately after cementing the 3-7!8 inch robing in the 7 inch tong string casing, and Event 3: July 1, 3004 -are-test of the June 17,'004 monitoring event, afer allowing the cement to cure. In the July 23, 3004, letter, American Soda, LLP (.~S) points out that the monitoring from Event 1 showed signal returns from as deep as 1209 feet, which correlates well with the depth of a crimp placed in the TDR cable. The monitoring from Events 3 and 3, however, only show signal returns from as deep as 1000 feet, and the aeazest crimp in the cable is at 101 ~ feet.