Ground-Water Quality at a Creosote Waste Site

An abandoned creosote facility in Conroe, Texas, has become a field site for the National Center for Ground Water Research (NCGWR) at Rice University. Ground-water contamination in the shallow aquifer beneath the site was characterized by sampling soils and water quality at 14 monitoring wells and 35 boreholes. Results from six sampling trips over two years for inorganic and organic chemical concentrations in the ground water show wells around the site were contaminated to levels above 800 μg/l for naphthalene, 400 μg/1 for methyl naphthalene, and 150 μg/1 for dibenzofuran. Conservative constituents, traced by chloride concentrations up to 75 mg/l, have migrated 300 ft (90 m) downgradient of the site. Organic contaminants have been adsorbed and microbially degraded in their migration from the waste source as evidenced by their attenuated concentrations. Detailed field pump tests have been performed to evaluate hydraulic conductivity at several of the shallow wells. The U.S. Geological Survey (USGS) Solute Transport Model (Konikow and Bredehoeft, 1978) has been used to predict chloride plume patterns and evaluate parameters which govern transport processes at the Conroe waste site.     

Groundwater Flow Near a Vertical Circulation Well with a Skin-Effect

Water Resources - Groundwater flow in the vicinity of a vertical circulation well is considered. The article presents solutions of problems of steady-state and transient groundwater flow near a...     

Simulating Errors in Statistical Tests of Leachate-lmpacted Ground-Water Quality

Data on 13 median leachate qualities at 56 landfills show a multivariate character, A simulation technique is used to include this multivariate character of leachate quality in assessing false negative error rates for statistical tests of ground-water quality. Although the technique makes gross simplifying assumptions regarding the conservative mixing of leachate and ground water, the technique is more appropriate than traditional statistical methods for simulating false negative error rates that neglect correlations among water quality parameters. The technique is applied to the simple case of a control chart, intrawell statistical test of ground-water contamination. Simulation results show that both the false positive and false negative errors of statistical tests can be reduced when tests include more parameters and a higher confidence level; thus, the technique can provide a “win-win” situation for regulators and the regulated.