The Department of Transportation’s newly-proposed rule for pipeline safety issued last week incorporates much of the recently passed pipeline safety legislation, and also extends the impact zone for “high consequence areas” (HCA) beyond the current 660 feet from large-diameter, high pressure pipelines.

The HCA definition for gas transmission lines originally was based on broad corridors that could potentially be impacted by a pipeline rupture and explosion. However, additional calculations have to be used to determine the likely actual area that would be impacted, the rule proposed by DOT’s Research and Special Programs Administration (RSPA) and the Office of Pipeline Safety (OPS) noted. The definitions of a potential impact circle and potential impact zone are based on a mathematical equation. But, the agency said an earlier HCA definition only addressed broad corridors or distances perpendicular to a pipeline, and neglected longitudinal distances (axially along the pipeline). The new definition now does both to better define “the actual area of impact in an HCA, and narrow the area to which the proposed assessment and repair requirements will apply.”

The expanded definition also “is based on the need to provide the same level of added protection to population groups, as the current HCAs provide to facilities that house people who are difficult to evacuate, people with impaired mobility, people who are confined, and areas where people congregate. This population group living at distances greater than 660 feet was inadvertently omitted from the definition when we proposed and later finalized the HCA definition.”

The proposed rule calls for initial assessments and periodic inspections as outlined in the “Pipeline Safety Improvement Act of 2002.” The new law provides for pipeline integrity inspections under which facilities with the highest risk factors will be given priority for completing inspections within a five-year period, which lawmakers interpreted as meaning at least 50% of gas pipeline facilities need to be inspected within the next five years. All facilities must be examined within 10 years. Pipelines then must be re-examined again in seven years. Also the transportation secretary will be able to order an operator to fix a pipeline that has a potentially unsafe condition. (see NGI, Dec. 23, 2002)

The rule proposes to require pipeline operators to:(a) Implement a comprehensive integrity management program; (b) conduct a baseline assessment and periodic reassessments focused on identifying and characterizing applicable threats; (c) correct defects; (d) and monitor the effectiveness of their programs. Pipeline operators would identify HCA and high risk areas of their lines for special treatment.

The rule also provides for addressing concerns raised by the federal OPS on behalf of a state authority. It does not apply to gas gathering or to gas distribution lines.

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