WSB was contracted to perform a comprehensive geohazard risk assessment, per PHMSA regulation (Section 192 of Title CRF 49), on 2,275 miles of designated transmission lines across Louisiana, Mississippi, Alabama, Tennessee, Arkansas, Oklahoma, and Missouri. The risk assessment program analyzed the geohazard risk of nine hazards: groundwater seepage, flooding, stream channel erosion (washout), sinkholes, seismicity, freeze-thaw, subsidence, slope failure, and active mining.
This project involved three major phases: (1) remote desktop modeling, (2) on-site field verification, and (3) final risk calculations and analyses. Remote desktop modeling was completed using Geographic Information System (GIS)-programming to model the occurrence, risk, and proximity of potentially active geohazards to designated transmission lines. Model input parameters, related to each type of geohazard, were extracted from publicly available data.
On-site field programs were used to verify remote modeling and document any evidence of hazardous conditions, pipeline damage, or exposure. Field programs consisted of traversing the transmission lines via appropriate rights-of-way (ROW) to collect data. Logged field site data included local geology, active hazardous conditions, evidence of past failure or hazardous conditions, causative factors of identified hazards, and pipeline damage or exposure, if any. All field data collected on-site was logged within GIS programming for geospatial accuracy.
After the completion of remote modeling and field programs, risk matrices for each hazard were developed to calculate the magnitude of potential consequences (level of impacts) and likelihood (level of probability) of those consequences occurring. Risk calculations were performed to (1) determine and communicate risk effectively and (2) provide a quantitative analysis of the highest priority sites for remediation and monitoring across all assets.