Laserfiche WebLink
Underground Injection Control Branch Guidance No. 5 <br />' • <br />w s~yg://3~/http://www.epa.gov/reg5oh2o/uidr5_OS.htm <br />2. If any anomalies are evident on the coarse log, construct a finer grid by making noise <br />measurements at intervals of 20 feet within the coarse intervals containing high noise level <br />Make noise measurements at intervals of 10 feet through the firs[ 50 feet above the injectio <br />interval and at intervals of 20 feet within [he 100-foot intervals containing: t) the base of tl <br />lowermost bleed-off zone above the injection interval, 2) the base of the lowermost USDW <br />and 3) in the case of varying water quality within the zone of USDW, the top and base of e. <br />interval with significantly different water quality from the next interval; <br />4. Additional measurements may be made to pinpoint depths at which noise is produced; and <br />5. Use a vertical scale of 1 or 2 inches per 100 feet. <br />E. Interpretation <br />The interpretation of noise logs for [he purpose of demonstrating part 2 of MI is quite <br />straightforward. The following steps are used: <br />1. Determine the base noise level in the well (dead well level); <br />2. Identify departures from this level. An increase in noise near the surface due to equipment <br />operating at the surface is to be expected in many situations; <br />3. Attempt to determine the extent of any movement, this may be difficult when there are few <br />Flow constrictions; <br />4. If Flow is into or between USDWs, a lack of mechanical integrity is indicated. If flow is frc <br />the injection zone of a hazardous-waste disposal well into or above the confining zone, fail <br />of containment is indicated. <br />If the log measurements are ambiguous, the determination should be confirmed using another <br />method. <br />ATTACHMENT 7 <br />OXYGEN ACTIVATION METHOD <br />A. Basis <br />The oxygen activation method is based on the ability of the tool to convert oxygen into Nitrogen <br />(N16) within a short distance of the tool. This is accomplished by emitting high energy neutrons i <br />the tool's neutron source. N 16 is an unstable isotope of nitrogen which is referred to as activated <br />oxygen. The half life of activated oxygen is just 7.13 seconds, and the release of gamma rays as tl <br />activated oxygen decays into oxygen can be measured. If [he tool is stationary and oxygen is <br />activated, detectors placed near the activator device will detect increased gamma radiation. The <br />intensity of the additional radiation will be inversely proportional to the square of the distance of <br />activated oxygen from [he detector. Much of the oxygen near [he tool occurs in water. If water <br />containing activated oxygen moves, [he measured intensity of radiation will be greater if the slug <br />23 of 34 526/99 1:09 PM <br />