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

3.
3

4.
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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5.
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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6.
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

7.
Building 88 Area Results
Membrane Interphase Probe (MIP)
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8.
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
9

9.
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)

10.
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)

11.
Groundwater Well Installation
Building 88 Area
6 monitoring wells were installed at the Building 88 Area
12

12.
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
13

13.
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

14.
Traffic Island Area Results
15

15.
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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16.
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
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PCE
Upper A-aquifer
(6 to 35 ft bgs)

17.
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)

18.
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
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PCE
B2-aquifer
(~78 to 100 ft bgs*)
* Two locations to 115 ft bgs

19.
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
20

20.
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
21

21.
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
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Soil from 63 feet bgs
at 28SI-06 had
positive Sudan dye
test

22.
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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23.
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
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Lower A-aquifer
(36 to ~78 ft bgs)

24.
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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25.
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

26.
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
27

27.
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
28

28.
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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29.
Questions?
Point of Contact:
Scott Anderson
BRAC Environmental Coordinator
(619) 532-0938
scott.d.anderson@navy.mil
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