Determination of reference concentrations for inorganic analytes in groundwater at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee
Background (or reference) concentrations for inorganics in Y-12 Plant groundwater were determined using a combination of statistical cluster analysis and conventional cumulative probability graphing. Objective was to develop a methodology for setting groundwater reference concentrations that uses all site groundwater data instead of only results of sampling upgradient of groundwater contamination. Y-12 was selected as prototype because the groundwater data set is very large and the data have been consistently collected since 1986. A conceptual framework of groundwater quality at Y-12 was formulated; as a quality check, data were statistically modeled or clustered. Ten hydrochemical regimes or clusters were identified. Six well clusters closely corresponded to the water quality framework and to observed water quality regimes in groundwater at Y-12. Four clusters were associated with nitrate, an S-3 Site contaminant, or with nonspecific contaminants commonly encountered at shallow depths at industrial sites (e.g., road salt). These four clusters were eliminated from the reference data set. Cumulative probability graphs were used within a cluster or group of clusters to distinguish contaminated wells from wells with ambient water quality. Only median values of unfiltered samples were plotted. Outlying data points (assumed to be contaminated samples) were identified and eliminated from the data set. When all outliers for a given inorganic had been identified and deleted from the data set, the reference concentration was set at the one-sided upper tolerance limit on the 95th percentile with 95% confidence. The methodology proved useful in integrating a large amount of data into the Y-12 plant groundwater conceptual framework and in identifying those wells or groups of wells that have monitoring or sample and analysis problems or that may be monitoring site-related contamination.
- Research Organization:
- Oak Ridge Y-12 Plant (Y-12), Oak Ridge, TN (United States); HSW Environmental Consultants, Inc., Oak Ridge, TN (United States); Paradigm Data Services, Inc. (United States)
- Sponsoring Organization:
- USDOE Office of Environmental Restoration and Waste Management, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 432798
- Report Number(s):
- Y/ER-234; ON: DE97001115
- Resource Relation:
- Other Information: PBD: Mar 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Calendar year 1995 groundwater quality report for the Chestnut Ridge Hydrogeologic Regime Y-12 Plant, Oak Ridge, Tennessee. Part 2: 1995 groundwater quality data interpretations and proposed program modifications
Groundwater Monitoring Report, U.S. Department of Energy Y-12 National Security Complex, Oak Ridge, Tennessee
Related Subjects
05 NUCLEAR FUELS
GROUND WATER
CONTAMINATION
MONITORING
POLYCHLORINATED BIPHENYLS
ECOLOGICAL CONCENTRATION
ORGANIC COMPOUNDS
Y-12 PLANT
SITE CHARACTERIZATION
LAND POLLUTION
CALIBRATION STANDARDS
WATER QUALITY
INORGANIC COMPOUNDS
WASTE MANAGEMENT
ENVIRONMENTAL QUALITY
NITRATES
VOLATILE MATTER