As a result of recent accidents, this notice proposes to require operators of distribution lines to use gas detectors in conducting leakage surveys on lines located outside business districts. Some operators now survey these lines for leaks by looking for dead or dying vegetation, a method that is less reliable than using gas detectors. The proposed rule would assure that operators detect all hazardous leaks during leakage surveys of distribution lines outside business districts. Also, at least every 3 years, operators must reevaluate certain cathodically unprotected metallic pipelines for the presence of active corrosion, using electrical survey or other means if -electrical survey is impractical. The means commonly used instead of electrical survey is assessment of leakage survey data. For distribution lines located outside business districts, that data may be as much as 5 years old under the present rule on survey frequency. Exclusive reliance on such old data, however, is not in keeping with the purpose of determining the presence of corrosion at least every 3 years. Thus, to assure that data no more than 3 years old are available for this purpose, RSPA is proposing that the lines involved be surveyed for leaks at least every 3 years. In addition, for distribution lines of any material located outside business districts, RSPA is seeking comment on (1) the need to shorten the maximum interval between leakage surveys from 5 years to 3 years, and (2) the need for annual leakage surveys on cathodically unprotected metallic lines on which electrical surveys are impractical.