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

Gridded MTBE, Water Levels

Model Domain Existing USGS model domain Local model

Water Level Calibration

8 Hour Pump Test Modflow Measured Log

Modeled Pathline

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.