Terasen’s high-pressure pipeline is located above the portal of an operating mine. Excavation of overburden to remediate the portal resulted in a very steep, 25 m-high slope below the pipeline. The portal was extended with a timber box structure and fill was placed to re-establish a milder slope below the pipeline. A drainage layer was placed at the bottom of the fill and around the timber tunnel section. However, it was grouted in the vicinity of the timber, which had undergone some displacement when the fill was placed.
Klohn Crippen Berger supervised a drilling investigation to assess the bedrock location and nature of overburden and performed static and seismic stability analyses to confirm that the long term stability of the reinstated slope was adequate. The influence of potential loss of drainage due to grouting in the timber structure vicinity was included in the analyses.
- Site investigation and laboratory testing
- Static and seismic stability analyses