Indirect and Direct Assessment

Our overall approach to corrosion risk assessment and corrosion mitigation:

Pre-assessment stage
Indirect assessment stage
Direct assessment stage
Recommendations for Remediation

Pre-assessment stage:

Desk study of soil types (USGS data) in the area.

Matergenics is the only company that maps the existing data into a GIS to create a corrosion map (soil corrosivity map) so that the assets that are most at risk can be easily identified, inspected, and protected. Please visit https://matergenicsgis.com/ for Additional Technical Details.

The collected data will be mapped on individual map layers, and all map layers will be combined to generate a Corrosion Risk Assessment Map. GIS corrosion map layers are input and weighted by Matergenics to construct the final corrosion map.

The final corrosion map identifies areas with low to severe risk of external corrosion. A proprietary method will be utilized for corrosion risk assessment. The method includes an algorithm to assign a corrosivity index to each location on the map based on soil properties, geological data, and external corrosion factors. The accuracy of this algorithm has been field-tested in several projects.

Indirect Assessment Stage

This involves desk study, review of inspection and failure reports and pre-assessment

Soil resistivity measurement (per ASTM G57: Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method), with different pin spacing to perform Barnes layer analysis. This allows calculating soil resistivity at specific depths.
Collection of soil samples in areas with a higher concentration of breaks or corrosive soils.
Chemical and corrosivity analysis of soil samples in Matergenics soils lab and modeling for remaining life.
Electrochemical potential measurements in areas with higher and lower concentration of water main breaks.
Look for correlations among the above data to identify “hot” areas for the direct assessment stage.

Direct Assessment Stage

This involves the condition assessment of cast iron water mains through on-site examination.

Perform direct observation and visual observation of pipe condition, with a major goal of determining whether the primary corrosion losses are internal (water side) or external.
Check for the presence of galvanic corrosion conditions

Measure level of graphitization – which is basically the corrosion-related deterioration of the cast iron microstructure which severely weakens the pipes – using a proprietary sensor device.