Line Walking Surveys for Buried Pipelines

Throughout the year, the BPA Lands Team constantly monitors and inspects our buried pipeline network to identify any potential threats or problems along the route. Among the various inspection methods, line walking surveys are perhaps the best at detecting issues that might not be apparent through other monitoring techniques.

What is a Line Walking Survey?

A line walking survey involves physically walking along the route of a buried pipeline to establish the condition of the surrounding environment. This practice is particularly effective in identifying localised issues such as ground movement, shallow cover, or encroachments that could pose a threat to the pipeline’s integrity.

While other survey methods like aerial or overline inspections provide a broader overview, line walking allows us to undertake a close-up assessment that can reveal subtle changes and potential hazards that might otherwise go unnoticed.

Legislative and Standard Requirements

In the UK, the maintenance of pipelines is governed by the Pipelines Safety Regulations 1996 (PSR), which, while not specifying line walking as a mandatory practice, emphasises the need for regular maintenance and inspection to ensure pipeline safety.

Regulation 13 of the PSR mandates that pipelines be maintained in an efficient state and in good repair. This regulation underscores the importance of regular inspections, including line walking surveys, to validate and maintain pipeline safety.

Industry standards also provide guidance on the frequency and conduct of line walking surveys. It is recommended that pipeline routes be walked at least once every four years unless a risks require a different frequency. Similarly, it is important for regular inspections to identify factors that could affect pipeline safety, such as third-party activities, ground movement, or environmental changes.

Risk-Based Approach to Line Walking

Given the varying environments through which pipelines traverse, a one-size-fits-all approach to line walking is not practical. Instead, a risk-based approach is undertaken where the frequency and focus of line walks are tailored to the specific risks associated with different sections of the pipeline. This approach considers factors such as the potential for ground movement, the proximity of the pipeline to populated areas, and the likelihood of third-party interference.

For example, pipelines located in areas prone to flooding, ground erosion, or significant human activity may require more frequent inspections. Conversely, sections of the pipeline in stable, less populated areas might be inspected less frequently. The risk-based approach ensures that resources are allocated efficiently, with more attention given to high-risk areas that are more likely to experience issues.

Our inspectors are equipped with the necessary tools to document their findings, such as GPS devices, cameras, and notebooks. They also have clear guidelines on what to look for, including the condition of marker posts, signs of ground movement, and any new developments in the area that could impact the pipeline.

What we Look For During a Line Walk

During a line walking survey, inspectors focus on identifying any signs of degradation or potential threats to the pipeline. Key areas of concern include:

• Marker Posts and Cathodic Protection (CP) Test Posts: These are critical for maintaining pipeline integrity. Inspectors ensure that they are intact and functioning properly.
• Signs of Ground Movement or Shallow Cover: Changes in the landscape, such as soil erosion or ground subsidence, can reduce the cover over the pipeline, increasing the risk of damage.
• New Developments: Construction activities or new buildings near the pipeline can pose a threat if not properly managed. Inspectors should be vigilant for any changes in land use.
• Third-Party Activities: Unauthorized activities near the pipeline, such as excavation or construction, are a significant risk and should be reported immediately.

Responding to Immediate Threats

If an immediate threat to the pipeline is identified during a line walk, our inspectors will take prompt action. This could involve stopping any nearby construction activities or marking the area for further investigation. Aquick response is crucial to preventing potential accidents or damage.

Post-Survey Actions

After completing a line walk, the team documents all findings comprehensively. This includes recording any issues identified, actions taken, and recommendations for further inspection or repair. Proper documentation ensures that all concerns are addressed and provides a record for future reference.

Line walking surveys are a vital component of pipeline integrity management. By allowing for close-up inspection of the pipeline and its environment, they help identify potential threats before they become critical issues.

If you see a member of BPA’s Lands Team undertaking a line survey on land near you, feel free to ask them any questions or concerns you may have about the buried pipeline network in your area.  Alternatively, contact the BPA’s lands team by clicking here.