Field comparison of groundwater sampling methods

Most ground-water sampling methods require the investigator to purge a large quantity of stagnant water from a well prior to collecting a sample. The use of in situ ground-water sampling devices which minimize or eliminate the need for purging would help to alleviate these problems. In this field comparison study, the performances of seven ground-water sampling devices, including two in situ sampling systems, were evaluated to determine if these devices would yield accurate, precise, and representative data. The sampling devices included a bladder pump, a bladder pump below an inflatable packer, a bailer, the Westbay{dollar}\sp\circler{dollar} Mp System, two in situ BAT{dollar}\sp\circler{dollar} devices, and a BAT{dollar}\sp\circler{dollar} well probe. The sampling devices were installed at a site contaminated by a benzene-chlorobenzene plume, and the comparison was based on the ability of the devices to recover representative concentrations of these volatile organic compounds. (Abstract shortened with permission of author.)