Former NAS Moffett Field

RAB Meeting

November 14, 2013

Valerie Harris, PE – Navy Remedial Project Manager

Neil Hey, PG - CB&I Federal Solutions

BRAC PMO West

Site 28 Supplemental Investigation

Presentation Overview

Site Background

Project Objectives

Technical Approach

Building 88 Area - Preliminary Results

Traffic Island Area – PreliminaryResults and Additional Planned Work

Questions

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Treatability Tests

Treatability tests were performed in three areas at Site28 between July 2010 and June 2011

Analytical results from treatability study wells in theBuilding 88 Area showed that the shallower“upgradient” well had the highest concentrations ofchlorinated ethenes.

Analytical results from observation wells in the TrafficIsland Area showed that the deepest treatment areawell had the highest concentrations of chlorinatedethenes.

These two areas were targeted for a supplementalinvestigation after the treatability tests were completeto better define the high concentration areas.

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Supplemental investigation is needed to:

1) Further delineate PCE & daughter products (TCE, DCE, & VC)in A-aquifer within & around the Former Building 88 & TrafficIsland source areas

2) Confirm depth & lateral continuity of A/B-aquitard in TrafficIsland Area

3) Verify depth to top of B2-aquifer in Traffic Island Area

4) Confirm whether existing well W88-1, located in the TrafficIsland Area, is screened in the B2-aquifer

5) Confirm whether B-aquifer beneath Traffic Island Area isimpacted by chemicals of concern above ROD cleanupstandards and MCLs (EPA, 1989)

Project Objectives

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Phase 1:

• SCAPS

Semi-quantitative COC concentration data (mg/Lof calibration solution). Membrane interphaseprobe (MIP) data are only considered estimates.

Results by MIP system are relative & should beverified by soil and groundwater.

Phase 2:

• Monitoring Well Installation/SoilSampling

• Groundwater Sampling

Technical Approach

Building 88 Area Results

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Membrane Interphase Probe (MIP)

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 groundwatersamples

• Monitoring Well Installation

• 6 groundwater monitoring wells

• Soil Sampling

• 2 to 3 samples from each well borehole

• Groundwater Sampling

• 2 rounds of samples collected9

SCAPS PCE Results – Upper A-aquiferFormer Building 88 Area

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GeneralGroundwaterFlow Direction

Maximum MIP/DSITMSResponse

PCE

Upper A-aquifer(6 to 35 ft bgs)

mg/Lcs denotes milligrams per literof DSITMS calibration solution

>100 mg/Lcs - DSITMS

>1 mg/Lcs - DSITMS

Not Detected

≥500 mg/Lcs - DSITMS

28SI-03 (10 – 20 ft bgs)

28SI-05 (9 – 19 ft bgs)

28SI-02 (10 – 20 ft bgs)

28SI-01 (10 – 20 ft bgs)

SCAPS PCE Results – Lower A-aquiferFormer Building 88 Area

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GeneralGroundwaterFlow Direction

Maximum MIP/DSITMSResponse

PCE

Lower A-aquifer(35 to ~67 ft bgs)

mg/Lcs denotes milligrams per literof DSITMS calibration solution

>100 mg/Lcs - DSITMS

≥1 mg/Lcs - DSITMS

Not Detected

28SI-12 (46 - 51 ft bgs)28SI-04 (39 - 49 ft bgs)

Groundwater Well InstallationBuilding 88 Area

6 monitoring wells were installed at the Building 88 Area

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Groundwater – PCE ResultsBuilding 88 Area

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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

28SI-03 (10 – 20 ft bgs)

PCE =not detected

4 shallow wells – screened ~10 to 20 ft bgs

Concentrations not indicative of source area

Groundwater – PCE ResultsBuilding 88 Area/Lower A

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28SI-12 (46 - 51 ft bgs)

PCE = 2,900 mg/L

28SI-04 (39 - 49 ft bgs)

PCE = 820 mg/L

2 deeper wells – screened 39 to 49 ft bgs & 46 to 51 ft bgs

Concentrations higher than shallow wells but we have existingdown gradient wells for definition

Traffic Island Area Results

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Investigation ActivitiesTraffic 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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SCAPS PCE Results – Upper A-aquiferTraffic Island Area

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GeneralGroundwaterFlow Direction

Maximum MIP/DSITMSResponse

PCE

Upper A-aquifer(6 to 35 ft bgs)

mg/Lcs denotes milligrams per literof DSITMS calibration solution

>1,000 mg/Lcs - DSITMS

>100 mg/Lcs - DSITMS

>5 mg/Lcs - DSITMS

Not Detected

28SI-08 (7 -17 ft bgs)

SCAPS PCE Results – Lower A-aquiferTraffic Island Area

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GeneralGroundwaterFlow Direction

Maximum MIP/DSITMSResponse

PCE

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

mg/Lcs denotes milligrams per literof DSITMS calibration solution

>1,000 mg/Lcs - DSITMS

≥100 mg/Lcs - DSITMS

≥3 mg/Lcs - DSITMS

Not Detected

>10,000 mg/Lcs - DSITMS

28SI-011 (48 -58 ft bgs)

SCAPS PCE Results – B2-aquiferTraffic Island Area

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GeneralGroundwaterFlow Direction

Maximum MIP/DSITMSResponse

PCE

B2-aquifer(~78 to 100 ft bgs*)

* Two locations to 115 ft bgs

mg/Lcs denotes milligrams per literof DSITMS calibration solution

>1,000 mg/Lcs - DSITMS

>100 mg/Lcs - DSITMS

>8 mg/Lcs - DSITMS

Not Detected

>10,000 mg/Lcs - DSITMS

28SI-07 (105 – 115 ft bgs)

28SI-09 (90 – 100 ft bgs)

28SI-10 (90 – 100 ft bgs)

28SI-06

(90 – 100 ft bgs)

Groundwater Well InstallationTraffic Island Area

• Wells installed from July 10 to 24, 2013 atlocations 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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Upper A-aquifer Groundwater Results

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28SI-08 (7 -17 ft bgs)

PCE = 300 mg/L

Well installed to provideinformation on the shallowgroundwater near Building 126

Lower A-aquifer Groundwater Results

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28SI-011 (48 -58 ft bgs)

PCE = 5,300 mg/L

• Well installed to provideinformation about groundwaterdowngradient of highconcentration area

• EPA considers PCE >1,000 mg/Lto be a “source”

• Positive Sudan dye test was at63 ft bgs in the Lower A-aquifer, but a well was notscreened at this depth

Soil from 63 feet bgsat 28SI-06 hadpositive Sudan dyetest

typical Sudan dye test

Additional Wells in Traffic Island

• 3 additional monitoring wells are planned forLower A-aquifer

– 2 collocated wells in down gradient direction

• Screen intervals of 32 to 42 feet bgs and 58 to 68feet 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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Proposed Additional Traffic Island Wells

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GeneralGroundwaterFlow Direction

Proposed New Well

Newly Installed Well

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

mg/Lcs denotes milligrams per literof DSITMS calibration solution

>1,000 mg/Lcs - DSITMS

≥100 mg/Lcs - DSITMS

≥3 mg/Lcs - DSITMS

Not Detected

>10,000 mg/Lcs - DSITMS

28SI-011 (48 -58 ft bgs)

28SI-14

(32 – 42 ft bgs)

28SI-13 (60 - 65 ft bgs)

28SI-15 (58 – 68 ft bgs)

A/B-aquitard

• SCAPS tests confirmed that predominately fine grainedsediments are present at all locations investigatedbetween ~ 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 ~3feet to >10 feet thick.

• However poorly graded sand with silt observed in wellboring 28SI-07 from 76 to 77.5 ft bgs; and clayey sandin well boring 28SI-10 from 76 to 78 ft bgs

• Aquitard may not be laterally continuous

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B2 Aquifer – Traffic Island

• Based on CPT data from 28 SCAPS tests, the B2 aquiferbegins 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-aquitardand top of the B2 aquifer (proj obj #4)

• Four new wells installed in the B2 aquifer inpredominately fine grained sediments (with thin siltysand layers)

– Screened interval 90 to 100 ft bgs:• 28SI-06; 28SI-09;28SI-10

– Screened interval 105 to 115 ft bgs:• 28SI-07

B2 Aquifer – Traffic Island Area

• Groundwater flow to thenorth-northwest

• High concentration areadefined by SCAPS tests withND response

• Low groundwaterconcentrations confirmednear ND response

• B-aquifer is impacted byCOCs above cleanupstandards (proj obj #5)

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PCE Groundwater Results

85 - 100 ft bgs

28SI-06:

PCE: 10,000 mg/L

28SI-10:

PCE: 9.5 mg/L

28SI-09:

PCE: 2.4 mg/LW88-1:

PCE: 260 mg/L

Results for Monitoring Well 28SI-07

Deepest well installed inTraffic Island Area

PCE result from August:9,500 mg/L

Total depth of SCAPSinvestigation waslimited by approvedscope

MIP response at bottomof hole was 400 mg/L-calibration solution

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Groundwater Results

100-115 ft bgs

28SI-07

PCE: 9,500 mg/L

Next Steps

• Install additional wells in Traffic Island Area

• Collect second round of groundwater samplesfrom the 12 newly installed monitoring wells

• Prepare Technical Memorandum

– Draft Technical Memorandum: May 2014

• Evaluate Path Forward for Treatment

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Questions?

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Point of Contact:

Scott Anderson

BRAC Environmental Coordinator

(619) 532-0938

scott.d.anderson@navy.mil