Background

South East Water’s operational water supply network, approximately 620 kilometres of underground water pipelines are constructed from mild steel. The pipelines range from 225 to 2100mm in size with construction dates ranging from 1905 to present. The arrangement of the water mains makes them electrically continuous and, in most instances, are subjected to corrosion due to reaction with the environment, galvanic contact with dissimilar metals or as a result from stray DC current pickup (electrolysis) originating from train and tram traction systems.

To identify pipeline corrosion activity SEW participate in two pipeline monitoring programs.

1.Pipeline Potential Survey

Pipeline potential surveys are conducted at intervals along a pipeline to provide an indication of corrosion resulting either from poor pipe coatings, contact with other pipelines, services or foreign structures, adverse interference effects from other cathodic protection systems or train and tram traction systems. Measured potentials are evaluated against criteria to determines the changes in pipeline potential with respect to the environment. Surveys indicate the effectiveness and requirement for corrosion mitigation system

2.VEC Area Testing

Under the legislative framework of the Energy Safe Victoria (ESV) the Victorian Electrolysis Committee (VEC) is responsible for the protection of underground structures such as water pipelines from stray current corrosion effects. Area testing involves underground structure owners and traction system operators working in a coordinated test including one or more adjacent traction substations in a nominated test area. Similar to Pipeline Potential Surveys, measurements are conducted at intervals along a pipeline to provide an indication of any adverse corrosion activity.

Contract Objectives

The outcomes that South East Water is looking for are as follows:

• Appoint a Corrosion Monitoring Contractor to perform activities to fulfill SEW’s pipeline potential measurement program.
• Appoint a Corrosion Monitoring Contractor to perform activities to fulfill SEW’s responsibility as a Structure Owner under the direction of the VEC.