Evaluation of Mine Surveying Practices and Their Influence on Reserve Estimation Accuracy at Selected Nigerian Mines

Accurate mine surveying underpins reliable reserve estimation, production reconciliation, and regulatory reporting at mining operations. This study evaluates mine surveying practices and their influence on reserve estimation accuracy at eight medium-scale mines in Plateau, Nassarawa, and Kogi states. Surveying methods in use at each operation were documented and benchmarked against the Society of Exploration Geophysicists and the South African Code for Reporting of Exploration Results, Mineral Resources and Mineral Reserves (SAMREC) standards. Survey data collected during the study period were used to independently re-estimate mineable reserves at three operations and compare results to operator-declared reserves. Discrepancies between surveying-based estimates and operator declarations were analysed for systematic bias. Findings reveal that five of the eight operations conduct surveys using only hand-held GPS devices, with positional accuracy inadequate for reserve grade block reconciliation. Two operations have not conducted topographic surveys in over four years, creating unquantified deviations between planned and actual mine geometry. Independent reserve re-estimation reveals operator overstatements averaging 23 percent relative to the study's surveying-based estimates. The study recommends mandatory adoption of total station and drone-based survey methods, minimum survey reporting standards, and annual third-party reserve audits as conditions of mining licences. Keywords: mine surveying, reserve estimation, Plateau State, Nassarawa State, mining accuracy.