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The No-Purge Scetuarno � (Lessons Learned) Thomas Wayne„ Kabis Background The essential importance of groundwater quality is now recognized as development of groundwater continues to expand Monitoring of groundwater quality is becoming increasingly more important due to public worries over chemical contamination The development of new equipment and techniques for measuring contaminants in minute concentrations without the additional production of hazardous and toxic wastes has been added to a list of sampling concerns. Accuracy and cost savings top the list of concerns surrounding the sampling and monitoring of groundwater The measure of cost savings when engaging in groundwater sampling is calibrated with many standards The most common standards involve the expenditure of manpower and raw materials for the collection of any one sample, suite of samples or for the conduct of an entire program of groundwater sampling. The expenditure of manpower and use of raw materials takes on a much more complicated meaning when viewed through an established sampling plan and to a greater extant, when compiling and publishing a sampling plan. First and foremost, it is necessary to understand the medium to be sampled, the environment in which the sampling is to take place, and exactly what is to be expected from the sampling event. It is also pertinent to consider the consequences of using any particular type of equipment or procedure, either based on the equipment itself, or on imposed standards. Current sampling standards are based on antiquated equipment and involve the production of large amounts of additional hazardous waste as a result of the sampling event, in order to obtain a repeatable average sample This produced waste, must then be discharged elsewhere or treated and discharged, generally adding greatly to the confusion of exactly what the regional chemical composition of groundwater is at any one site There has been much study completed on the problem of obtaining representative groundwater samples from rapidly recovering ground-water monitoring wells Scalf, et. al. reported in a 1981 paper that bacterial activity can dramatically affect VOC analysts results Dissolved VOCs can effervesce in as little as 2 hours after sample acquisition. Seanor and Brannaka noted in their 1983 paper that water in ground-water monitoring wells is stagnant, this means that, typically, water standing in a well is usually considerably above the screened interval and this water is not in communication with formational water This standing water is subject to different chemical equilibria and often has different pH, Eh, temperature, and dissolved solids Wilson and Dworkin reported in their 1984 paper that rust and scale from ground-water monitoring wells may interfere with laboratory analyses, as may the presence of colloids and clay platelets Barcelona and Helfrich concluded in 1986, that no or improper purging of a ground-water monitoring well was a greater cause for sampling error than was sampling . method, well construction materials, or sampler materials They went so far as to state that improper purging was the dominant error factor