Pipeline Safety: Grant of Waiver; Portland Natural Gas Transmission System

AGENCY:

Research and Special Programs Administration (RSPA); U.S. Department of Transportation (DOT).

ACTION:

Notice; grant of waiver.

SUMMARY:

PNGTS Operating Co., LLC, operator of the Portland Natural Gas Transmission System (PNGTS), requested a waiver of compliance with the regulatory requirements at 49 CFR 192.611 that require natural gas pipeline operators to confirm or revise the maximum allowable operating pressure of their natural gas pipelines after changes occur in Class location.

SUPPLEMENTARY INFORMATION:

Background

PNGTS Operating Co., LLC, operator of the Portland Natural Gas Transmission System, submitted a request to RSPA's Office of Pipeline Safety (RSPA/OPS) seeking a waiver of compliance with the regulatory requirements at 49 CFR 192.611 to confirm or revise the maximum allowable operating pressure of its natural gas pipeline after Class location changes occurred in areas associated with two sections of the pipeline totaling 595 feet in length in West Stewartstown, New Hampshire. In lieu of complying with the § 192.611 requirements, PNGTS proposed to conduct certain alternative risk control activities on the pipeline that exceed the minimum requirements of Part 192. These activities included performing internal inspections at six-year intervals on the entire 24-inch mainline, annual close-interval cathodic protection surveys on the waiver segments, a direct current voltage gradient survey on the waiver segments, direct assessment and repair of any anomalies identified by the inspections and electrical surveys, and more frequent ground and aerial surveillance patrols and instrumented leak surveys on the pipeline.

PNGTS requested a waiver of compliance with the requirements at 49 CFR 192.611 to confirm or revise the pipeline's MAOP for the referenced portions of its pipeline based on the following reasons:

1. The size of the geographic areas associated with the waiver segments is minimal. The area associated the two waiver segments is only 595 feet in length.

2. The construction activity that resulted in the Class location change was minimal and is not expected to expand further. The construction consisted of several mobile homes and two multi-tenant structures containing four units each on the perimeter of a tree farm. The multi-tenant units cross the 660-foot Class boundary by distances of only 0.7 to 22.8 feet. In addition, the mobile home park is now at capacity and is unlikely to expand due to the sloping terrain in the area and property ownership constraints.

3. The pipeline was constructed as recently as 1999 and hydro tested during the fourth quarter of 1998 to a pressure of 1,806 psig. Having been in service for only four years, the pipeline is nearly new and in excellent condition. No deficiencies were identified in a baseline close-interval cathodic protection survey conducted in 2000, and no anomalies were identified on or near the waiver segments in a baseline internal inspection conducted in 2002 with both magnetic flux leakage and geometry in-line inspection tools.

4. The pipeline's operating history has been trouble-free. No leaks have been identified anywhere on the PNGTS pipeline since it was put into service.

5. The pipeline is equipped with a satellite-linked supervisory control and data acquisition (SCADA) system, including pressure transmitters and mainline valves equipped with remote control actuators enabling PNGTS to identify and promptly mitigate any releases in the vicinity of the waiver segments should they occur.

6. The proposed alternative risk control activities would provide a margin of safety and environmental protection that equals or exceeds that of the measures required under § 192.611 in the absence of a waiver.

7. Granting the waiver would avoid the delivery interruptions and costs associated with excavating and replacing the pipe in the specified areas.

8. The proposed alternative risk control activities would benefit virtually the entire pipeline system, as opposed to only the 595 foot portion associated with the Class location change.

After reviewing the waiver request, RSPA/OPS published a notice inviting interested persons to comment on whether a waiver should be granted (Notice 1) (68 FR 66156; Nov. 25, 2003). RSPA/OPS stated that it was considering granting the requested waiver because of the minimal distance by which the structures cross the Class boundary, the age and condition of the pipeline, and the additional inspection and monitoring activities on which the waiver would be conditioned. No comments were received from the public in response to the notice.

For the reasons explained above and in Notice 1, and in light of the equivalent level of safety provided by the alternative risk control activities, RSPA/OPS finds that the requested waiver is not inconsistent with pipeline safety. Therefore, PNGTS's request for waiver of compliance with 49 CFR 192.611 is granted on the condition that PNGTS conducts the following activities:

1. Perform internal inspections on the entire 143.8 miles of 24-inch pipeline in 2008 and subsequent internal inspections at intervals not to exceed six years. The internal inspections must be performed using both magnetic flux leakage and geometry in-line inspection tools capable of detecting metal loss, dent-like deformations, and other integrity threats;

2. Perform annual close-interval cathodic protection surveys on the Class 3 sections of the pipeline, as well as an additional 1000 feet of the Class 1 or 2 pipe on both the upstream and downstream ends of these sections;

3. Perform annual direct current voltage gradient surveys on the Class 3 sections of the pipeline, as well as an additional 1000 feet of the Class 1 or 2 pipe on both the upstream and downstream ends of these sections;

4. Perform assessments and appropriate repairs of all anomalies or other indications of corrosion identified by the internal inspections and electrical surveys, regardless of the size or depth of the anomaly;

5. Perform weekly aerial patrols and quarterly ground road crossing patrols over the entire 143.8 miles of 24-inch pipeline. The ground road crossing patrols must include leak surveys on all Class 3 portions of the pipeline using appropriate instrumented leak detection equipment; and

6. Perform semi-annual leak surveys on the portion of the pipeline extending from Mile Post (MP) 0.0 to MP 6.80 using appropriate instrumented leak detection equipment.