JD Mollard and Associates

JDMA was retained to investigate the geological and hydrogeological setting of a rupture on a high pressure natural gas pipeline. Study tasks included compilation of regional and local geological data, review of stratigraphy and historical piezometric water levels in a network of groundwater wells, air photo terrain analysis of the site and surrounding area, collection of ground electrical conductivity data using and EM31 and EM38 conductivity meters, excavation of test holes, description of stratigraphy and material sampling, and collection of ground water and sediment samples for microbial analysis.

Study results demonstrated a correlation between the rupture mechanism and fluctuating seasonal ground water levels and the local transition from ground moraine to glaciodeltaic sediments with high and fluctuating water table. Anomalous levels of microbial activity were also present at the rupture site. Data and analysis from the site were used to assist the client with assessing susceptibility to a similar type of failure elsewhere on their pipeline system.

Terrain mapping and site characterization