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~~R"b~ UNITED~ATES ENVIRONMENTAL PROT~-ION AGENCY _~„ REGION VIII ~~ 999 78th STREET -SUITE 500 DENVER, COLORADO 80202-2466 i Luc - s is~~ SUBJECT: GROUND WATER SECTION GUIDANCE NO. 37 Demonstrating Part II (external) Mechanical Integrity for a Class II injection wellyp permit. FROM: Tom Pike, Chief ///~~/ ~C UIC Direct Implement8tion Section TO: All Section Staff Montana Operations Office During the review for a Class ZI injection well permit, consideration must be given to the mechanical integrity (MI) of the well. MI demonstrates that the well is in sound condition and that the well is constructed in a manner that prevents injected fluids from entering any formation other than the authorized injection formation. A demonstration of MI is a two part process: PART I - INTERNAL MECHAZTICAL INTEGRITY is an assurance that • there are no significant leaks in the casing/tubing/packer system. PART II - EETERNAL ?iECBANICAL INTEGRITY demonstrates that after fluid is injected into the formation, the injected fluids will not migrate out of the authorized injection interval through vertical channels adjacent to the wellbore. A Class II injection well may demonstrate Part II MI by showing that injected fluids remain within the authorized injection interval. This may be accomplished as follows: 1) Cement bond log showing 80t bond through the an appropriate interval (Section Guidance 34), 2) Radioactive tracer survey conducted according to a EPA- approved procedure, or 3) Temperature survey conducted according to a EPA- approved procedure (Section Guidance 38). For each test option above, the operator of the injection well should submit a plan for conducting the test. The plan will then be approved (or'Llodified and approved) by EPA. EPA's pre- approval of the testing method will assure the operator that the test is conducted consistent with current EPA guidance, and that the test will provide meaningful results. PYinNd on Ree~cled Peper