This final rule requires operators of distribution lines located outside business districts to use leak detectors to carry out required leakage surveys. Instead of using leak detectors, some operators survey for leaks by looking for dead or dying vegetation, a less reliable method. The rule will provide greater assurance that operators identify all hazardous leaks during required leakage surveys. Also, where electrical surveys for corrosion are impractical on cathodically unprotected metallic distribution lines located outside business districts, operators commonly use leakage survey data to determine whether the lines are corroding. However, under the present leakage survey standard, those data may be too old for purposes of evaluating lines for corrosion at 3-year intervals. Thus, the final rule assures that leakage survey data no more than 3 years old are used to evaluate lines for corrosion.