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

Hampton Bays

Source

Contaminationfirst identified

Shallow bay

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

Model Domain

Source

Contamination

Source

Shallow bay – constant head

Plume Centerline

Anthropogenic Recharge

Gridded MTBE

Modeled Pathline - XY

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 Well

Highest Concentration

along IRM~ 10,000 ug/L

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?

New Well(s)

Concentration21,000

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

Salient Point

Even at some of the most well characterized sites, there is detail that is not captured. A model calibrated to the data will always miss these details – but the possibilities can be investigated.