Hampton Bays
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Hampton Bays
• At least one UST release• MTBE, TAME• TBA degradation product• Upper Glacial; Magothy• Sensitive shallow saline surface water discharge• IRM rate• In-situ follow-up?
Critical Prediction
Maximum MTBE concentration at Interim Remedial Measure well for number and sizing of Air Stripping Towers –
• Limited space• Neighborhood
- Location pre-determined
Characterization
• Multi-level transects across plume• Typically 8 to 12 nested sampling/wl points• Oxygenates, BTEX, EAs• No full single sampling event yet• Typical representative sample: Volume: 100,000 c-ft (x porosity)*Area: 300 sq-ft (x porosity) Spacing: 40 ft
* Long Island ‘Rule of Thumb: 50,000 to 100,000 c-ft
Modeled Pathline - RZ
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
0 500 1000 1500 2000 2500
Distance of Travel (Feet)
Ele
va
tio
n (
ft-M
SL
)
FIELD: DataMODEL: Inc. RCH = 44MODEL: Uniform RCH
IRM - Recovery
• Predicted from mass-flux:~ 2,500 ug/L
• Predicted from model:~ 2,500 ug/L
• Actual:~ 6,300 ug/L
• Dilution only 1.5:1? OR
• Extra Mass?
Current Work
Examine maximum-concentrations that could exist in the plume centerline, consistent with measured data
• Postulate XYZ locations of several points in plume centerline• Estimate values at points• Krig points onto existing starting concentrations until best match