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Uniondale, NY. At least two UST releases MTBE mass release estimated 7,000 lb Upper Glacial; Magothy Threatened PWS deeper in Magothy IRM design In-situ follow-up?. Critical Prediction(s). Mass removal rate at Interim Remedial Measure wells (4) for sizing of Air Stripping Towers*
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Uniondale, NY • At least two UST releases • MTBE mass release estimated 7,000 lb • Upper Glacial; Magothy • Threatened PWS deeper in Magothy • IRM design • In-situ follow-up?
Critical Prediction(s) Mass removal rate at Interim Remedial Measure wells (4) for sizing of Air Stripping Towers* Maximum concentration at public supply well Probable source *IRM location f(constructibility)
Characterization • Multi-level transects across plume • Typically 8 to 12 nested sampling/wl points • Oxygenates, BTEX • One full single sampling event • Typical representative sample: Volume: 120,000 c-ft (x porosity)* • Area: 500 sq-ft (x porosity) * Long Island ‘Rule of Thumb: 50,000 to 100,000 c-ft
Characterization Flow PWS
Model Domain Existing USGS model domain Local model
8 Hour Pump Test Modflow Measured Log
Current Investigation • Calibration of recharge with cemetary, drainage basin, roadside run-off collection of interest • Targets: • XYZ path of particle through plume centerline • Concentrations * Long Island ‘Rule of Thumb: 50,000 to 100,000 c-ft
Recharge Basin Area of increased recharge
IRM - Recovery • Predicted from mass-flux: • Early 250 Max 800 ug/L • Predicted from model: • Early 200 Max 900 ug/L • Actual: • Early 200 ug/L* * Weighted average of samples
Salient Point Presentation of a model’s reasonableness, goodness of fit, calibration, reliability, should always be in terms of the prediction for which the model was built. Other methods may be misleading.