STEDIN CASE STUDY
STEDIN NV SAVES €80,000 PER WEEK ON SERVICE LINE MAINTENANCE PLANNING WITH SKYGEO INSAR
1.9 million service lines at risk
Dutch utility Stedin NV manages over 23,000 kilometers of gas distribution pipelines and is responsible for 1.9 million gas service line 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 of failure and ensure that they are maintained first. InSAR is at the heart of risk-based asset management.
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.
Existing repair targets all pipelines and causes unnecessary digging for diagnostics.
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.
Details:
Industry: civil engineering, geotechnical engineering
Use Case: underground pipelines
Product: PSI, verification and validation, geostatistics
“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.
Subsidence in the Portland area causes failures in gas delivery.
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.
Targeting service line repair based on actual subsidence rates
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.
SkyGeo delivered over 30,000 subsidence rate measurements in the Portland subdivision.
The weak link addressed: 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 has become 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.
Risk-based asset management: strategy and planning
Asset Managers and Network Operations Planners can access the risk 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.
An interpolated risk map detailing subsidence velocity within each street. The outlines of the houses and streets are shown in grey. Stedin could determine the expected subsidence impact per front door. Inset top left: zoom-in of the interpolated street-level subsidence map. Individual homes, garages and streets are outlined in grey. Inset bottom right: zoom-in of the risk map. Service lines going into homes in green (stable) areas are assigned low risk status, service lines in red areas subside rapidly and are assigned high risk.
Civil Engineering Case Studies
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City of Rotterdam
We can help cities everywhere to prevent damage before it happens, by using InSAR and analyzing these deformations with millimeter precision.
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City of Diemen
“Problems we had for years with manual measurements were resolved at once.”
