A comprehensive desk study was recently carried out to assess the potential resources of sand and gravel in the drift deposits of County Durham. The study was based on published information, limited field observations and the analysis of 6000 subsurface datapoint references and over 1700 particle size distribution results. It was necessary, therefore, to devise a system of analysis which could provide an objective and repeatable assessment of the sand and gravel deposits and their resource potential on a regional basis.
The evaluation system previously adopted by the Industrial Minerals Assessment Unit (IMAU) for the sand and gravel resource assessments conducted by the British Geological Survey was reviewed. This system comprises a statistical procedure to classify the investigation data and gives arbitrary physical criteria to determine whether a deposit can be regarded as ‘potentially workable’.
The principal data available to the IMAU for each of their resource assessments were specifically gathered for the project under their direct supervision. The IMAU system could not be applied to the Durham study because data for this study were obtained totally from third-party sources.
A system of analysis was designed which was sensitive to the variation in data quality. It is based on a flow chart comprising both question/answer and action elements and incorporates the arbitrary physical criteria adopted by the IMAU. The system is described in this paper and the effectiveness and limitations are demonstrated with reference to the Durham study.