This Technical Report is a summary of best practice for those involved in geophysical borehole logging for hydrogeological purposes. It describes the factors that need to be considered and the measurements that are required to be made when logging boreholes. There can, however, be no definite "standard" logging procedure because of great diversity of objectives, ground-water conditions and available technology. Geophysical logging of boreholes is an evolving science, continually adopting new and different techniques. Every application poses a range of problems and is likely to require a particular set of logs to gain maximum information. This Technical Report therefore provides information on field practice with the objective of how variations in measured parameters may be useful to take account of particular local conditions. It deals with the usual types of logging carried out for delineation of aquifer boundaries; mapping aquifer geometry; assessing the chemical quality and quantity of ground water; water-supply purposes; landfill investigations and contamination studies; borehole construction and conditions; and subsurface lithological information.

Applications not specifically considered in this Technical Report include mineral and hydrocarbon evaluation and geotechnical and structural engineering investigations. However, this Technical Report may be a source of general information for any borehole geophysical logging effort.

NOTE Interpretation of the data collected during logging is referred to in this Technical Report only in a general way. For full details of the analysis and interpretation of geophysical logs, reference should be made to specialized texts. Examples of such texts are included in the Bibliography.