26 May 2014

Assisting New Zealand’s TCC with pipe and valve criticality assessments

We assisted New Zealand’s Tauranga City Council (TCC) urban infrastructure planners by providing them with a pipe and valve criticality assessment.

We assisted New Zealand’s Tauranga City Council (TCC) urban infrastructure planners by providing them with a pipe and valve criticality assessment. The pipe and valve criticality ranking was used as one of the main criteria in the city’s regular network reconstruction plan – part of its infrastructure rehabilitation planning programme.

Tauranga is a coastal city in the North Island of New Zealand and the TCC supplies water to approximately 120,000 customers every day. TCC has long-term aspirations for the use of criticality levels, which represent consequences of the failure of the water distribution pipes. Adding the probability of failure allows for the development of a risk-based replacement programme.

Pipe criticality develops a pipe ranking based on their importance for the water supply. Pipe criticality is assessed by modelling a distribution system response to pipe breaks, planned reconstructions, and other scenarios of limited water supply. Valve criticality analysis aim to find what valves needs to be closed in order to replace the selected valve. Calculated number of closed valves is used to define the valve criticality ranking.

The TCC asset management system provides the necessary inputs to the city’s infrastructure planners to help them in optimising TCC investments and network maintenance costs. It’s based on the ESRI ArcGIS platform – a geographic information system that entails working with maps and geographic data. In addition to the required pipe and valve criticality assessment results, TCC needed to periodically update their criticality statuses for both planning and operational purposes.

As such, we used our water distribution WD-Tools for Arc Map for the criticality assessments, as the tools are fully compatible with the TCC asset management system. Our tools helped them update pipe and valve criticality status in-house, as and when required.

Valve criticality is a powerful tool, providing operational and maintenance staff with the on-line, accessible information to open and close valves for operational and maintenance purposes and to understand the immediate impact on customers. The resultant savings in time and cost and the consequent effective communication with customers is invaluable. TCC operators aim to make use of the provided WD-Tools for Arc Map and its outputs when preparing for planned pipe or valve replacement as well as during emergency pipe burst situations, when fast action is required. Calculated pipe and valve criticality assessment ranking allows TCC to implement the infrastructure asset operational importance into their long-term rehabilitation planning programme.