Pipeline Safety Interpretation PI-80-0101

Page 1PI-80-0101 May 22, 1980 Mr. John E. Myrick Manager, Technical Services Northwest Alaskan Pipeline Company Fluor Engineering and Constructors, Inc. 3333 Michelson Drive Irvine, California 92730 Dear Mr. Myrick: One of the proposed construction modes for the Alaska portion of the Alaska Natural Gas Transportation System to be used north of the Brooks Range specifies a five feet deep trench. Although a berm would be constructed over the pipeline to provide protection, the cover from the top of the pipe to the natural ground level would only be one foot. I discussed with you on May 8, 1980 in Hanover, New Hampshire the possibility that this mode of construction might not comply with the cover requirements of the Minimum Federal Safety Standards for gas pipelines contained in 49 CFR 192.327(a). A minimum cover of 30 inches in normal soil or 18 inches in consolidated rock is required in a class 1 location. It is not stated in the regulation from what point the cover is measured in order to assure compliance. However, there is some guidance given from past interpretations. One such interpretation dated December 3, 1976 states in part: “Section 192.327 of the regulations prescribes minimum cover for transmission lines and mains measured at the time of construction from the ground surface or the bottom of a drainage ditch, as applicable.” The term "ground surface" would indicate that the cover would be measured from the natural ground level before ditch excavation. I would suggest that you request an interpretation of the regulation to eliminate any possibility of conflict with the cover requirement. Please forward any such request to my office and I will expedite a response to the request within the Materials Transportation Bureau. Sincerely, Original Sign By Lloyd W. Ulrich Acting Associate Director for Alaska Pipeline Materials Transportation Bureau#

Page 2Northwest Alaskan Pipeline Company 1801 K Street, N. W. Washington, D.C. 20006 August 28, 1980 Mr. Lloyd W. Ulrich Acting Associate Director, Alaska Pipeline Materials Transportation Bureau Department of Transportation Washington, D.C. 20590 Re: Interpretation of 49 CFR 192.327(a) Dear Mr. Ulrich: Section 192.327(a) of the Code of Federal Regulations, Part 49 specifies the minimum cover required for the installation of transmission lines. However, the point from where the depth of cover should be measured is not specified. On the 48" natural gas pipeline to be constructed in Alaska as part of the Alaska Natural Gas Transportation System, an interpretation might, therefore, be required in every case where the mode of pipeline burial differed from the normal buried mode. We have been interpreting Section 192.327 to mean the following: The word "cover" shall mean "the minimum depth or thickness of backfill around the pipe measured from any point on the circumference of the pipe." We understand that where the Code is not explicit in dealing with a special case, an interpretation from the Office of Pipeline Safety Operations will provide the necessary authority, unless there is a significant departure from the code. Therefore, an official interpretation is requested of the word "cover," perhaps a determination that our interpretation is acceptable. Yours truly, Northwest Alaskan Pipeline Company Edwin (Al) Kuhn Director Governmental Affairs#

Page 3United State Government Department of Transporation Research and Special Programs Administration MEMORANDUM Date: September 5, 1980 Subject: Request for Interpretation of 49 CFR Part 192 From: Acting Associate Director for Alaska Pipeline, DMT-50 To: Acting Associate Director for Pipeline Safety Regulation, DMT-30 Attached is a request from Al Kuhn of Northwest Alaskan Pipeline Company for an interpretation of 49 CFR 192.327(a) concerning depth of cover and specifically the point from where the depth of cover should be measured. I would appreciate your Office processing Mr. Kuhn's request and provide me with an interpretation so that I can respond to his letter.#