Supply of sand and crushed rock in The Gambia : visit findings by the British Geological Survey, December 2024

This report details a visit by the British Geological Survey (BGS) to The Gambia in late 2024 focused on disseminating research findings from work completed in The Gambia as part of BGS International Geoscience Research and Development (IGRD) programme. The visit and meeting in The Gambia were aimed at sharing knowledge from this recent work to Geological Department of The Gambia to support sustainable management of sand supply chains. This is a follow-up to a 2023 visit, expanding its scope to include crushed rock aggregate alongside sand. The study seeks to address shortages caused by the depletion of coastal dune sands and identify alternative materials to reduce reliance on imports. Activities consisted of laboratory training in particle-size analysis and fieldwork to better understand mineral supply chains in The Gambia. The report findings are that marine dredged sand from Denton Bridge has temporarily resolved sand shortages in The Gambia by providing a reliable supply even during the rainy season. However, the operation is nearing its end-of-life due to resource depletion, shifting focus to alternative marine extraction sites. These sites may alleviate inland mining pressure but may pose significant coastal erosion risks. Coastal impact assessments and stakeholder involvement are critical for sustainable extraction. Laterite fines, a byproduct of local quarrying, show potential for manufactured sand, though further characterization is required due to their high clay content fine grain sizes and strengths. Crushed laterite could substitute imported basalt aggregate for construction but requires careful use as it is weaker than traditional materials.