Chris Martin writes: The Glossop Award is made annually to an outstanding engineering geologist under the age of 30. The Engineering Group of the Geological Society has decided that it should go in 2009 to Stacy English of W A Fairhurst & Partners for her presentation ‘Rockfall Protection of Jamestown Wharf, St Helena.’
W A Fairhurst & Partners were appointed by St Helena Government to undertake a rockfall protection scheme on a 200m high, 400m long basaltic cliff on the island of St Helena, South Atlantic Ocean. Stacy played a key role in each stage of the scheme from the early review of previous studies, through the field data collection and design process, preparation of tender documentation and supervision of the construction phase of the works. Due to unusual travel constraints, because the island has no airfield facilities, the initial site visit was limited in time and a high level of organisation was essential to ensure that all the necessary data was obtained for the design process.
Initial activities included targeted rope access stability inspections and a number of field trials to gain an understanding of the behaviour of the failure masses. The cliff, which sits immediately above Jamestown Wharf, was characterised with respect to its geological formation, principal rock types and structural controls, together with the typical failure mechanisms and block sizes. Rock trials included trajectory surveys and vertical drop experiments to establish site specific parameters for rockfall models and for model calibration purposes. The final design included standard and reinforced rockfall containment netting, together with rockfall catch fences to provide the required level of risk reduction to Jamestown Wharf, while ensuring a safe and efficient construction method. The system was also designed to be straightforward to safely maintain, making it feasible for this to be carried out by trained local labour resident on the island, without the need for constant external specialist intervention.