1. Former NAS Moffett Field
Site 28 Supplemental Investigation
RAB Meeting
November 14, 2013
Valerie Harris, PE – Navy Remedial Project Manager
Neil Hey, PG - CB&I Federal Solutions
BRAC PMO West
2. Presentation Overview
Site Background
Project Objectives
Technical Approach
Building 88 Area - Preliminary Results
Traffic Island Area – Preliminary
Results and Additional Planned Work
Questions
2
5. Treatability Tests
Treatability tests were performed in three areas at Site
28 between July 2010 and June 2011
Analytical results from treatability study wells in the
Building 88 Area showed that the shallower
“upgradient” well had the highest concentrations of
chlorinated ethenes.
Analytical results from observation wells in the Traffic
Island Area showed that the deepest treatment area
well had the highest concentrations of chlorinated
ethenes.
These two areas were targeted for a supplemental
investigation after the treatability tests were complete
to better define the high concentration areas.
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6. Project Objectives
Supplemental investigation is needed to:
1) Further delineate PCE & daughter products (TCE, DCE, & VC)
in A-aquifer within & around the Former Building 88 & Traffic
Island source areas
2) Confirm depth & lateral continuity of A/B-aquitard in Traffic
Island Area
3) Verify depth to top of B2-aquifer in Traffic Island Area
4) Confirm whether existing well W88-1, located in the Traffic
Island Area, is screened in the B2-aquifer
5) Confirm whether B-aquifer beneath Traffic Island Area is
impacted by chemicals of concern above ROD cleanup
standards and MCLs (EPA, 1989)
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7. Technical Approach
Phase 1:
• SCAPS
Semi-quantitative COC concentration data (mg/L
of calibration solution). Membrane interphase
probe (MIP) data are only considered estimates.
Results by MIP system are relative & should be
verified by soil and groundwater.
Phase 2:
• Monitoring Well Installation/Soil
Sampling
• Groundwater Sampling
9. Building 88 Investigation Activities
SCAPS Investigation – (Feb 2013 RAB)
•
•
24 SCAPS tests to 70 feet below ground surface
Soil Sampling and Grab Groundwater Sampling
•
•
9 discrete soil samples and 9 grab groundwater
samples
Monitoring Well Installation
•
•
6 groundwater monitoring wells
Soil Sampling
•
•
2 to 3 samples from each well borehole
Groundwater Sampling
•
•
2 rounds of samples collected
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10. SCAPS PCE Results – Upper A-aquifer
Former Building 88 Area
mg/Lcs denotes milligrams per liter
28SI-05 (9 of DSITMS bgs)
– 19 ft calibration solution
General
Groundwater
Flow Direction
28SI-03 (10 – 20 ft bgs)
≥500 mg/Lcs - DSITMS
>100 mg/Lcs - DSITMS
>1 mg/Lcs - DSITMS
28SI-02 (10 – 20 ft bgs)
Not Detected
28SI-01 (10 – 20 ft bgs)
Maximum MIP/DSITMS
Response
PCE
Upper A-aquifer
10
(6 to 35 ft bgs)
11. SCAPS PCE Results – Lower A-aquifer
Former Building 88 Area
General
28SI-04 (39 - 49 ft bgs)
Groundwater
Flow Direction
mg/Lcs denotes milligrams per liter
of DSITMS calibration solution
28SI-12 (46 - 51 ft bgs)
>100 mg/Lcs - DSITMS
≥1 mg/Lcs - DSITMS
Not Detected
Maximum MIP/DSITMS
Response
PCE
Lower A-aquifer
11
(35 to ~67 ft bgs)
13. Groundwater – PCE Results
Building 88 Area
28SI-03 (10 – 20 ft bgs)
PCE =not detected
28SI-05 (9 – 19 ft bgs)
PCE = 150 mg/L
28SI-02 (10 – 20 ft bgs)
PCE = 35 mg/L
28SI-01 (10 – 20 ft bgs)
PCE = 14 mg/L
4 shallow wells – screened ~10 to 20 ft bgs
Concentrations not indicative of source area
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14. Groundwater – PCE Results
Building 88 Area/Lower A
28SI-04 (39 - 49 ft bgs)
PCE = 820 mg/L
28SI-12 (46 - 51 ft bgs)
PCE = 2,900 mg/L
2 deeper wells – screened 39 to 49 ft bgs & 46 to 51 ft bgs
Concentrations higher than shallow wells but we have existing
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down gradient wells for definition
16. Investigation Activities
Traffic Island Area
SCAPS Investigation
•
•
•
28 SCAPS tests to 100 feet
2 SCAPS tests to 115 feet
Monitoring Well Installation
•
•
6 wells
Soil Sampling
•
•
2 to 3 samples from each well boring
Groundwater Sampling
•
•
new wells, two sampling events
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17. SCAPS PCE Results – Upper A-aquifer
Traffic Island Area
mg/Lcs denotes milligrams per liter
of DSITMS calibration solution
>1,000 mg/Lcs - DSITMS
>100 mg/Lcs - DSITMS
>5 mg/Lcs
28SI-08 (7 -17 ft bgs) - DSITMS
Not Detected
Maximum MIP/DSITMS
Response
General
Groundwater
Flow Direction
17
PCE
Upper A-aquifer
(6 to 35 ft bgs)
18. SCAPS PCE Results – Lower A-aquifer
Traffic Island Area
mg/Lcs denotes milligrams per liter
of DSITMS calibration solution
>10,000 mg/Lcs - DSITMS
>1,000 mg/Lcs - DSITMS
≥100 mg/Lcs - DSITMS
≥3
28SI-011 (48 -58 ft bgs)mg/Lcs - DSITMS
Not Detected
Maximum MIP/DSITMS
Response
General
Groundwater
Flow Direction
18
PCE
Lower A-aquifer
(36 to ~78 ft bgs)
19. SCAPS PCE Results – B2-aquifer
Traffic Island Area
mg/Lcs denotes milligrams per liter
of DSITMS calibration solution
>10,000 mg/Lcs - DSITMS
>1,000 mg/Lcs - DSITMS
>100 mg/Lcs - DSITMS
>8 mg/Lcs - DSITMS
Not Detected
28SI-10 (90 – 100 ft bgs)
28SI-06
(90 – 100 ft bgs)
28SI-09 (90 – 100 ft bgs)
Maximum MIP/DSITMS
Response
28SI-07 (105 – 115 ft bgs)
General
Groundwater
Flow Direction
19
PCE
B2-aquifer
(~78 to 100 ft bgs*)
* Two locations to 115 ft bgs
20. Groundwater Well Installation
Traffic Island Area
• Wells installed from July 10 to 24, 2013 at
locations based on results of the SCAPS
• Upper/Lower A-aquifer
– One shallow well (screened 7 to 17 ft bgs)
– One well screened 48 to 58 feet bgs
• B2-aquifer
– Three wells screened 90 to 100 feet bgs
– One well screened 105 to 115 ft bgs
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21. Upper A-aquifer Groundwater Results
28SI-08 (7 -17 ft bgs)
PCE = 300 mg/L
Well installed to provide
information on the shallow
groundwater near Building 126
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22. Lower A-aquifer Groundwater Results
28SI-011 (48 -58 ft bgs)
PCE = 5,300 mg/L
• Well installed to provide
information about groundwater
typical Sudan dye test
downgradient of high
concentration area
• EPA considers PCE >1,000 mg/L
to be a “source”
• Positive Sudan dye test was at
63 ft bgs in the Lower Aaquifer, but a well was not
screened at this depth
22
Soil from 63 feet bgs
at 28SI-06 had
positive Sudan dye
test
23. Additional Wells in Traffic Island
• 3 additional monitoring wells are planned for
Lower A-aquifer
– 2 collocated wells in down gradient direction
• Screen intervals of 32 to 42 feet bgs and 58 to 68
feet bgs
• Provide definition of source area
– 1 at location of observed DNAPL ganglia
• Screen interval from 60 to 65 feet bgs
• Installation planned for early December 2013
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24. Proposed Additional Traffic Island Wells
mg/Lcs denotes milligrams per liter
of DSITMS calibration solution
>10,000 mg/Lcs - DSITMS
>1,000 mg/Lcs - DSITMS
28SI-14
(32 – 42 ft bgs)
≥100 mg/Lcs - DSITMS
28SI-15 (58 – 68 ft bgs)
28SI-011 (48 -58 ft bgs)
≥3 mg/Lcs - DSITMS
Not Detected
Proposed New Well
Newly Installed Well
28SI-13 (60 - 65 ft bgs)
General
Groundwater
Flow Direction
24
Lower A-aquifer
(36 to ~78 ft bgs)
25. A/B-aquitard
• SCAPS tests confirmed that predominately fine grained
sediments are present at all locations investigated
between ~ 75 and 78 ft bgs.
• These materials are considered to be the A/B-aquitard
• It varies in thickness in the Traffic Island Area from ~3
feet to >10 feet thick.
• However poorly graded sand with silt observed in well
boring 28SI-07 from 76 to 77.5 ft bgs; and clayey sand
in well boring 28SI-10 from 76 to 78 ft bgs
• Aquitard may not be laterally continuous
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26. B2 Aquifer – Traffic Island
• Based on CPT data from 28 SCAPS tests, the B2 aquifer
begins about 78 feet bgs (proj obj #2)
• Existing deep well W88-1 is screened (72 to 82 ft bgs)
across the interval of the lower A-aquifer, A/B-aquitard
and top of the B2 aquifer (proj obj #4)
• Four new wells installed in the B2 aquifer in
predominately fine grained sediments (with thin silty
sand layers)
– Screened interval 90 to 100 ft bgs:
• 28SI-06; 28SI-09;28SI-10
– Screened interval 105 to 115 ft bgs:
• 28SI-07
27. B2 Aquifer – Traffic Island Area
28SI-10:
• Groundwater flow to the
PCE: 9.5 mg/L
north-northwest
• High concentration area
defined by SCAPS tests with
28SI-09:
W88-1:
PCE: 2.4 mg/L
ND response
PCE: 260 mg/L
• Low groundwater
28SI-06:
concentrations confirmed
PCE: 10,000 mg/L
near ND response
• B-aquifer is impacted by
COCs above cleanup
PCE Groundwater Results
standards (proj obj #5)
85 - 100 ft bgs
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28. Results for Monitoring Well 28SI-07
Deepest well installed in
Traffic Island Area
PCE result from August:
9,500 mg/L
Total depth of SCAPS
investigation was
limited by approved
scope
MIP response at bottom
of hole was 400 mg/Lcalibration solution
28SI-07
PCE: 9,500 mg/L
Groundwater Results
100-115 ft bgs
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29. Next Steps
• Install additional wells in Traffic Island Area
• Collect second round of groundwater samples
from the 12 newly installed monitoring wells
• Prepare Technical Memorandum
– Draft Technical Memorandum: May 2014
• Evaluate Path Forward for Treatment
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