PIPELINE SAFETY ADVISORY BULLETIN
ADVISORY BULLETIN: ADB-99-04
Date: August 23, 1999

To: Owners and Operators of Hazardous Liquid and Natural Gas Pipeline Facilities

Summary: PHMSA is issuing this advisory bulletin to owners and operators operators of natural gas and hazardous liquid pipeline systems to advise them to review, and amend if necessary, their written damage prevention program to minimize the risks associated with directional drilling and other trenchless technology operations near buried pipelines. This action follows several pipeline incidents involving trenchless technology operations which resulted in loss of life, injuries, and significant property damage. It also corresponds to National Transportation Safety Board (NTSB) Safety Recommendation P-99- 1, which suggests that PHMSA * * * ensure that the operators' damage prevention programs include actions to protect their facilities when directional drilling operations are conducted in proximity to those facilities. This advisory bulletin emphasizes the importance of having procedures to mitigate the risks of directional drilling and other trenchless technology.

Subject: Directional Drilling and Other Trenchless Technology Operations Conducted in Proximity to Underground Pipeline Facilities

Purpose: To ensure that pipeline operators take actions to recognize the dangers associated with directional drilling and other trenchless technology operations, and to ensure that underground pipeline facilities are adequately located and protected from inadvertent damage.

Advisory: PHMSA urges all owners and operators of gas and hazardous liquid pipelines to review their operations, maintenance, and damage prevention programs to include effective actions to protect their underground facilities from the dangers posed by directional drilling and other trenchless technology operations. Operators should take actions to ensure that both company and contractor personnel are following safe practices.

Trenchless technologies, including directional drilling, are effective [[Page 46968]] excavating practices that can reduce the threat of third-party damage to gas and hazardous liquid pipelines. They can also mitigate environmental and other concerns associated with traditional trenching methods of pipe and cable installation.

However, the potential exists for trenchless technology operations to damage underground facilities, sometimes with catastrophic results. Directional drilling and other trenchless technology operations employ a variety of cutting, jetting, boring, reaming, and jacking techniques. These techniques can result in rupture or damage to existing underground facilities, including oil and gas pipelines, electric cables and ducts, water and sewer pipes, telecommunications ducts, fiber optic cables, and cable television facilities.

Usually, the exact depth of existing underground facilities is not known, even if the facilities are accurately located before directional drilling commences. In addition, many facilities are buried deeper than the minimums required by law and regulation. This can be caused by changes in the surface contours due to agricultural activities, landscaping, and road building. Damage to underground facilities can occur without any immediate indication to the operator. Sometimes a damaged underground facility will not fail for years after the completion of trenchless technology operations. Drilling equipment does not need to fully rupture a facility to create a hazardous situation.

Damage to coatings and other corrosion prevention systems can increase the risk of a delayed corrosion failure. Escaping and migrating gas can create a safety issue for people living and working near these facilities long after the completion of directional drilling and other trenchless technology operations. Leakage from a damaged or ruptured hazardous liquid pipeline can create environmental and safety issues.

The primary safety concern is ensuring that trenchless technology operations do not accidentally contact existing underground facilities. This can be averted by knowing the precise locations of all underground facilities in proximity to trenchless technology operations. In addition to full compliance with the one-call notification process, the operator should also consider thorough site surveys of the area of a proposed directional drilling or trenchless technology project to locate potential conflicts with underground facilities.

Information on the safe conduct of trenchless technology operations is available from various trade associations and technical publications. In addition, the Gas Piping Technology Committee, a standards committee composed of experts on gas piping issues, publishes guidelines for planning and designing trenchless technology pipe installations in its Guide for Gas Transmission and Distribution Piping Systems, which is available from the American Gas Association.

Background: PHMSA revised its inspection form for hazardous liquid pipelines to examine how operators monitor directional drilling and other trenchless technology operations in the vicinity of underground pipelines. The pipeline safety regulations require pipeline operators to carry out a written damage prevention program for buried pipelines. The revised inspection form considers whether a pipeline operator's damage prevention program includes actions to protect their facilities when directional drilling operations are conducted in proximity to the pipeline. PHMSA will make similar changes to the natural gas pipeline inspection form in its next revision. In light of recent accidents involving trenchless technology operations, PHMSA is encouraging operators to carefully review their damage prevention program and make modifications as appropriate. PHMSA also notes the importance of accurately locating underground piping and ensuring the qualifications of personnel performing this work.

Additionally, NTSB Safety Recommendation P-99-1 (April 28, 1999) directs that PHMSA [w]hen reviewing pipeline operator safety programs, ensure that the operators' damage prevention programs include actions to protect their facilities when directional drilling operations are conducted in proximity to those facilities.

This recommendation reflects NTSB's investigation into the rupture of a natural gas pipeline near Indianapolis, Indiana. The ignition of the escaping gas caused a fatality and an injury. NTSB determined that the probable cause was the failure of the pipeline operator to ensure that safe directional drilling operations were conducted in proximity to underground facilities.

PHMSA believes that this Advisory Bulletin will encourage operators to recognize the dangers associated with directional drilling and other trenchless technology operations and to take appropriate action to ensure that underground facilities are adequately located and protected when these activities take place near pipelinethese facilities.

For further information, contact Eben M. Wyman, (202) 366-0918, or by email at eben.wyman@rspa.dot.gov.

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