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Selective Repairs Provide Stedin NV with Significant Savings

By October 15, 2020February 23rd, 2022No Comments

Stedin NV saves €80,000 per week on service line maintenance

A SkyGeo Case Study

Selective repair targets only pipelines at risk and avoids unnecessary digging.

Dutch utility, Stedin NV manages over 23,000 kilometers of gas distribution pipelines and is responsible for 1.9 million connections into homes in the Netherlands. By using SkyGeo’s door-by-door displacement risk estimates, Stedin staff can identify those pipelines with the highest risk and ensure the are maintained first. This approach as led to significant savings in their maintenance budgets.

Ivo Visser, Risk Analyst explains the significant savings made by this company

“With SkyGeo’s door-by-door displacement measurements, Stedin removes the most risk per euro we invest in maintenance.”
Ivo Visser, Risk Analyst, Stedin NV

The weak link: gas service lines in subsiding cities

Most houses in The Netherlands’ soft soil are built on a foundation so they do not subside.

Gas distribution pipelines on the other hand subside with the soil. This creates a hinge point where the gas service pipeline enters the building. These connections are prone to breaking. The severity of displacement directly correlates with problems in gas delivery service. Therefore displacement-related maintenance is part of Stedin’s long-term planning.

Previously, Stedin’s knowledge of displacement effects on risk was based on estimations from 1 soil sample per 10,000 m2 This is not good enough, because ground displacement in soft-soil areas is a heterogeneous process: within a street, one service line can be okay, and a few doors down, a service line can experience severe strain due to settlements.

Real scheduled maintenance planning required more detailed information on displacement. Now SkyGeo provides a direct estimate of displacement effects on distribution lines from door to door, across Stedin’s entire service area.

Actual effects of displacement on the most vulnerable part of a service line which can be seen floating in subsiding ground.

Subsidence in the Portland area

Just south of the city of Rotterdam, the Portland subdivision was built on four artificial islands. In this area, complaints about the gas delivery service were filed routinely in recent years. Visible signs of rapid displacement in the roads coincided with high incidence of broken service lines.

Standard maintenance procedure was scheduled and would have dictated replacement of the majority of over 800 pipeline service connections. This scheduled maintenance would have progressed from connections in West Portland first, to the East last.

Where no damage is found for several connections in a row, the maintenance is skipped. The operation was budgeted for more than €850,000. Stedin’s asset manager decided to apply actual displacement measurements as a proxy for risk in order to prioritize the maintenance activities. SkyGeo‘s satellite-based displacement measurements started with 30,000 displacement time series in the 3 km2 area. The data shows 5 years of dynamic displacement history of streets, buildings and other objects.

The measurements were used to create a street-level displacement map. This showed displacement rates up to 3 cm per year, distributed unpredictably over the area. Ultimately, only 20% of the service lines in the area were found to be at high risk due to displacement, including the area where the customer complaints originated. Stedin decided to prioritize maintenance on this 20% of the connections.

The other parts of the area are monitored. As a test, Stedin dug out 5 random pipeline connections selected from the other, low risk 80%. These samples confirmed no damage from displacement at all as predicted based on our data.

An interpolated risk map detailing displacement velocity within each street that Stedin uses to determine the expected displacement impact per front door.

The weak link: gas service lines in subsiding cities

Based on the results in Portland, Stedin decided to use SkyGeo’s high resolution data to map displacement risk for the rest of its service area with 1.9 million subscribers.

Stedin becomes the first gas distribution company in the world to have this innovative system operational for its network. Implementing the displacement maps Realizing the importance of accurate and detailed displacement measurements, Stedin has implemented these maps in their corporate asset management infrastructure.

Asset Managers and Network Operations Planners can access the data in a GIS environment, while field personnel can view data on a tablet. Specifically, service lines are identified where likely no displacement occurs.

Nowadays, before scheduled maintenance gets done by a field crew, the planner assesses the displacement risk. Since digging up and checking an individual connection costs up to €1,500, Stedin has saved hundreds of thousands of euros in Portland alone while reducing customers’ exposure to construction.

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