AN INTEGRATED STUDY OF CONTROLS ON SOLUTE TRANSPORT IN THE LINCOLNSHIRE LIMESTONE

A study site located in a quarry on the Lincolnshire Limestone has bee n selected to examine the validity of the 'dual porosity' hypothesis a nd its application in models for the prediction of solute migration. A n integrated approach has been adopted for the experimental programme, combining data obtained from both field and laboratory-scale investig ations with mathematical modelling. The results of the first to stages of the experimental developments at the site are reported and the res ults are discussed in relation to he development of a full tracer test programme. Fracture mapping has been conducted on the face and the fl oor of the quarry where the vertical fractures are seen to be disconti nuous over depth. However, extensive horizontal bedding plane fissures are readily identifiable in the boreholes and represent the main path s for lateral flows. An extensive data collection programme has been c onducted to characterize the hydraulic properties of these fissures, a s well as the adjacent altered and unaltered matrix. Important results for future tracer testing were obtained from the hydraulic tests whic h suggest the strong possibility of non-Darcian flow in the fissures u nder pumping and tracer test conditions and the probability of strong spreading of solutes at injection wells under forced inflows. Prelimin ary tracer tests confirm the difficulty of employing laboratory define d diffusion coefficients as input data to 'dual porosity' models of lo cal-scale transport.