Columbia Gas Distribution Companies — Pipeline Safety Interpretation

Page 1February 11, 1993 Ms. Marjorie H. Brant Columbia Gas Distribution Companies 200 Civic Center Drive P.O. Box 117 Columbus, OH 43216-0117 Dear Ms. Brant: This responds to your letter of February 4, 1993, to George W. Tenley, Jr. in which you ask our opinion if, using an HFI, would a standard bar hole depth of 10" be an acceptable operating technique for conducting a leakage detection survey on a liquid propane distribution system as required by §192.723(b). I am enclosing a January 8, 1993, letter from William H. Gute, Regional Director, Eastern Region, to the Virginia Corporation Commission responding to that question. I trust that this adequately responds to your inquiry. Sincerely, Cesar De Leon Director Regulatory Programs Office of Pipeline Safety dal\192\723\93-02-11 1#

Page 2January 8, 1993 Mr. Massoud Tahamtani Utilities Manager Virginia State Corporation Commission Jefferson Building P.O. Box 1197 Richmond, VA 23209 Dear Mr. Tahamtani: This is in response to your letter dated October 26, 1992, to Mr. Cesar DeLeon, Director, Regulatory Programs, Office of Pipeline Safety, requesting interpretations of Code §192.625(a) (Odorization of Gas) and §192.723(b) (Leakage Surveys and Procedures - Relating Specifically to Liquid Propane Gas Distribution Systems). The Eastern Region has discussed these Code Sections with Mr. DeLeon and as the result, we offer the following: 1. Concerning §192.625(a): A violation does not automatically exist if an operator, during random tests, finds an inadequate level of odorant in his distribution system (assuming the operator can demonstrate a history of adequate levels of odorant in his system). However, when an inadequate level is discovered, prompt action must be taken by the operator to insure that the level is increased to acceptable limits. The operator must be able to demonstrate that prompt action was taken. If for example, an unacceptable odorant level is discovered and the remedy involves increasing the injection rate of the odorizer servicing that particular area, then the operator must note that an adjustment was made (either to his test document sheet or at least some type of daily log), thus demonstrating that prompt action was taken. Obviously, some time must pass before the adjustment of the odorizer effects the area where insufficient odorant levels were discovered. Consequently, a follow-up test must be conducted by the operator in a timely manner to insure that the prompt action taken by the operator has sufficiently increased the level of odorant in the problem area. dal\192\723\93-02-11 2#

Page 32 2. Concerning §192.723(b): You may with to consult the Gas Piping Technology Committee (GPTC) Guide for Gas Transmission and Distribution Piping System, 1990-91, Guide Material Appendix G-11A, Gas Leakage Control Guidelines for Petroleum Gas Systems for guidance in further determining the instruments and techniques to be used in leak detection of liquid propane distribution systems. In your letter, you noted the following different methods presently being used by operators in Virginia: 1) Bar hole to a depth at or below main and use CGI, 2) Bar hole to a depth of ten inches and use HFI, and; 3) Mobil Survey using HFI. According to Appendix G-11A, any of the methods above "may be employed, as applicable, singly or in combination, in accordance with written procedures". You will note from this Appendix on Page 302, Section 4.4(a)(2), copy attached, that "The required depth of the test hole will depend upon the soil conditions, the depth of and pressure in the pipeline, and the type of instrument being used". Consequently, method No.2 above would be acceptable if soil conditions are such that the partial vacuum created by the HFI unit enabled the taking of "consistent and worthwhile readings". Should you have any questions, please don't hesitate to contact me. Sincerely, William H. Gute Eastern Regional Director dal\192\723\93-02-11 3#

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