Overview

The owner of two natural gas transmission pipelines with diameters of 20” and 26” respectively, were subject to disturbance from longwall mining activities occurring far beneath the pipelines. The longwall mining process causes the surface above, including the pipelines, to sink 1-3 meters as coal and minerals were removed from far below. Open trenching the pipelines protected them during the settling after the mining, but both lines had three crossings; two roads and one stream that could not be open trenched. As a result, we were employed to review plans and recommend alternate solutions for the crossings.

Solution Details

Proposed solutions included customized corrugated culverts, geotextile buoyancy control systems, and heavy duty bridge decking. This was in order to ensure the safety and stability of the crossings, as well as satisfy the West Virginia Department of Transportation standards. Some of the services provided by Entech included a brief assessment of environmental encroachments, review of drawings, trench box design/cost estimates, site location map development, pothole and stream detail, and exploration of other options. Such options focused on constructability, pipe clearance, cost, maintenance access, and reusability. The options provided allowed the client to make a more informed decision to protect the integrity and safety of their pipelines.