Groundwater sample handling

This chapter aims to provide a step-by-step guide for practitioners involved in the collection of contaminated samples by reviewing current groundwater sampling techniques and procedures and highlighting the major sources of uncertainty associated with sample collection. On-site water-quality measurements, quality assurance procedures and sample handling techniques designed to maintain the representativeness of the sample from field to laboratory are also discussed. 

Trick J. K., Stuart M., and Reeder S. describe the tools available to the field sampler for the collection of groundwater samples, methods of on-site water quality analysis, and the appropriate preservation and handling ofsamples. The authors discuss the merits of different purge methodologies and show how on-site measurements such as pH, specific electrical conductance (SEC), oxidation—reduction potential (ORP), dissolved oxygen (DO), temperature, and alkalinity can be used to provide a check on subsequent laboratory analyses. Techniques for the preservation and analysis of samples and quality assurance and quality control are also presented. 

Because hydrogeological systems, and hence groundwater bodies, are complex and often hard to monitor, it is difficult to establish formal quality control criteria for the whole programme. It is therefore recommended to establish criteria for each stage of the process as part of a quality plan. Certain elements are well controlled, e.g. sample handling, laboratory analysis and data management, but others, such as conceptual... 

Because of these findings, groundwater at the plant site was sampled and found to contain trichloroethylene. Apparently, improper handling and spill procedures led to the build-up of a pool of highly contaminated groundwater on-site. 

So long as sample collection, handling and preservation methods are satisfactory, pore-waters obtained by squeezing tend to be representative of in situ conditions when compared to chemical compositions of relevant groundwaters or pore-waters obtained by other methods (Bath 1993 Bath et al. 1996 Cottour 1997). 

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