(Certified Best Practice by BMPCOE)
Mason & Hanger Corporation, Pantex Plant - Amarillo, TX
Mason & Hanger Corporation (M&H) found that rapid purging of the well caused changes in the pH of the groundwater samples such that they were no longer representative of the actual groundwater values. M&H similarly found that the groundwater sample bottle must be filled in a particular manner in order to obtain repeatable data--seemingly insignificant items such as rapidly pouring the water sample into the bottle or wiping of the threads of the bottle can have a major impact on the quality of the groundwater sample and resulting data. For example, a 1991 set of total organic carbon data from a well (consisting of 4 data points) could be interpreted that the correct value was either 3 ppm or 15 ppm. A similar set of 1993 data following the improvement of the sampling process shows more consistency, with all values ranging between 1.0 ppm and 1.6 ppm.
As a result of the review of groundwater sampling practices, M&H has found that scrupulous care is required in all groundwater sampling actions, and that consistency in work patterns is critical.
A M&H groundwater monitoring review resulted in M&H examining its processes for establishing well locations, acquiring groundwater samples, and evaluating data from more than 30 wells located at Iowa Army Ammunition Plant (IAAP). As a result of the review, M&H corrected water table elevation data on several wells and installed additional wells where needed to monitor a landfill site. A critical benefit from the 1992 review of the groundwater monitoring program is the identification of improved processes for obtaining groundwater samples. Because the composition of the water in a well changes as it stands for months, the well must be purged and allowed to re-fill just prior to taking the groundwater sample.
Detailed groundwater wimple acquisition plans have been developed and are carefully allowed to ensure high quality data that can then be sued with confidence for monitoring and remediation purposes. M&H also realized a spillover benefit as a result of the groundwater sampling process improvements, as a better understanding of the importance of careful and repeatable techniques has also resulted in the improvement o other laboratory processes.