FIELD TRIALS OF ACTIVE AND MULTIPORT SOCK SAMPLERS IN GRAVEL-PACKED WELLS

Four novel sampling systems were tested for their ability to obtain level-representative groundwater samples from two gravel-packed boreholes in different hydrogeological settings at Skrydstrup (Denmark) and Torgau (Germany). Samples obtained with the novel devices were compared with those obtained from nearby permanent dedicated reference systems. Results obtained using the novel samplers vary from excellent agreement to no agreement. Numerical analysis was carried out in an attempt to understand the variation in the sampling results. Investigation showed that a single perfect sampler does not exist for these sites. Level-determined groundwater samples in gravel-packed wells can be obtained using active as well as multi-port sock samplers. The choice of the sampler depends mainly on the specific hydrogeological conditions, well completion, the type of pollution and the time available for sampling.