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Network Innovation Allowance
GD - Reliability and maintenance and GT - Reliability and maintenance
Asset Management, Maintenance & Inspection, Gas Distribution Networks and Gas Transmission Networks
The nature of LTS pipeline easements represents an asset management complexity. The monitoring methods used for transmission pipelines include aerial surveillance using helicopters and foot patrols along the pipeline route. These patrols prevent developments and events which could place the pipelines, the surroundings of pipelines or security of supplies at risk. Although these methods ensure a high level of safety in pipeline operation, the cost is also very high. Various agricultural practices remain permitted over the pipeline corridor, and recent changes in environmental policy allows natural processes such as lateral river movements across floodplains to go on unchecked by human intervention. It was once the case that artificial network defences were constructed, whereas now rivers migrate unimpeded. Where such river migrations place parts of the gas network at-risk, network licensees are responsible for redirecting their assets to accommodate these environmental changes.
Where allowable, visual inspections of around 2,400km of LTS network are conducted by helicopter surveys on a fortnightly basis. Helicopter surveys include a Raptor system of GPS-tagged full motion video, and the ability to annotate threat observations by on-board surveyors in real-time. In a small number of cases, immediate threats require the safe landing of the survey helicopter and direct intervention. Most threat observations however undergo secondary assessment through a systematic post-flight log review by asset managers. Subject to the nature and severity of the threat observed, asset managers will initiate any number of response mechanisms as defined by policy. Whether the threat is deemed an immediate threat or a normal threat observation, we face difficulty with the speed in which it may respond to a threat at all. For immediate threats, activities could conceivably have been occurring for up to 13 days prior to the survey acquisition, or it may be unsafe to land adjacent to an immediate threat, further delaying intervention.
Policy guidelines of fortnightly surveying is the result of risk/affordability assessment at the time of policy drafting, rather than a decision around the safety margin criticality for detecting and responding to threats in a timely manner. The policy goes further to state, “An aerial survey of all pipelines should be undertaken every two weeks. Normally, this activity is completed by an observer from a helicopter but can also be achieved by fixed wing aircraft or by the use of satellites.” As the existing policy contemplates multi-modal surveying techniques, the status quo of our current practices around LTS monitoring may be enhanced by using satellite imagery to reduce the overall risk to the high-pressure pipeline infrastructure and so deliver enhanced value to network customers.
The Stage 1 project represents a feasibility study to understand how satellite remote sensing (SARS), Visible Near Infrared (VNIR) and Short-Wave Infrared (SWIR) may best support the operational routine detection of such events to improve the expedition of intervention detection through a greater collection frequency, and over the longer term replace the traditional helicopter/walking surveys.
The status quo of our current practices around LTS monitoring may be enhanced in two ways, both of which would reduce the overall risk to the high-pressure pipeline infrastructure and so deliver enhanced value to network customers:
The nature of threat detections.
It may be possible using Synthetic Aperture Radar (SAR) and/or Visible Near Infrared (VNIR) and/or Short-Wave Infrared (SWIR) satellites for remote monitoring to improve the overall detection process across the complex asset network.
The timeliness of threat detections.
The satellite sensors have improved revisit rates over what was achievable just a few year ago. This coupled with; wide-area acquisition in a single overpass; cloud penetrating properties of SAR imaging; and sophisticated change detection algorithms and high-performance automated processing environments translates to an improved temporal window between threat initiation and threat detection.