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Person

Craig Brown

Research Hydrologist (Geol)
Email: cjbrown@usgs.gov
Office Phone: 860-291-6766
Fax: 860-291-6799
ORCID: 0000-0002-3858-3964

Location
339 Main Street
East Hartford , CT 06118-0000
US
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This dataset contains water-quality data, quality-control data, and input and output data for geochemical models that support the findings of a study of lead in drinking water in the Sturbridge, Massachusetts, study area. These data include major and trace element data for unfiltered and filtered (dissolved) samples collected from both taps and well heads at private well sites, and quality-control data, including blank sample data and replicate sample data. The computer program PHREEQC (Parkhurst and Appelo, 2013) was used with the water-quality data and the WATEQ4F thermodynamic database (Ball and Nordstrom, 1991) to calculate aqueous and surface speciation; mineral saturation index (SI=log (IAP/K), where IAP is...
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A boosted regression tree (BRT) model was developed to predict pH conditions in three-dimensions throughout the glacial aquifer system (GLAC) of the contiguous United States using pH measurements in samples from 18,258 wells and predictor variables that represent aspects of the hydrogeologic setting. Model results indicate that the carbonate content of soils and aquifer materials strongly controls pH and when coupled with long flow paths, results in the most alkaline conditions. Conversely, in areas where glacial sediments are thin and carbonate-poor, pH conditions remain acidic. At depths typical of drinking-water supplies, predicted pH > 7.5 – which is associated with arsenic mobilization – occurs more frequently...
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Hydrogeologic and Geochemical Assessment of the Effects of Leakage from the Catskill and Delaware Aqueducts on the Local Bedrock and Overburden Aquifers in Southeastern New York
PROBLEM As part of an effort to sustain a viable water-supply system for 8 million residents in New York City, and 1 million other residents in upstate New York that rely on City water, the New York City Department of Environmental Protection (NYCDEP) has requested a multi-disciplinary study by the U.S. Geological Survey (USGS) to determine the source(s) of water to surface-water sites (springs and expressions) in areas adjacent to the Catskill Aqueduct. In the area near the Delaware Aqueduct, which has been determined by the USGS to have a water-tunnel contribution to flooding issues during periods of high precipitation, the NYCDEP plans to repair the leaks with a grouting procedure. However, without monitoring...
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This dataset provides analytical and other data in support of an analysis of lead and manganese in untreated drinking water from Atlantic and Gulf Coastal Plain aquifers, eastern United States. The occurrence of dissolved lead and manganese in sampled groundwater, prior to its distribution or treatment, is related to the potential presence of source minerals and specific environmental factors including hydrologic position along the flow path, water-rock interactions, and associated geochemical conditions such as pH and dissolved oxygen (DO) concentrations. A DO/pH framework is proposed as a screening tool for evaluating risk of elevated lead or manganese, based on the occurrence of elevated lead and manganese concentrations...
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