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Triad Case StudyMarine Corps Base Camp Pendleton

U.S. EPA Office of Superfund Remediation and Technology Innovation

Streamlined Investigations and Cleanups Using the Triad Approach

CA DTSC Delivery � Cypress, CA

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Camp Pendleton is located in Northern San Diego County, and occupies some of the last remainig open space between Orange County and San Diego.

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Site 1114 Background� Site 1114 identified in 2003 because PCE

concentrations in well at adjacent site increased from 4 ug/L to 97 ug/L between 1993 when LTM ROD was signed and 2002

� MW 9W-07A is a cross-gradient perimeter well for Site 9, the former Waste Stabilization Pond

Figure 2-1. Water Quality Hydrograph,

PCE in 9W-07A GroundwaterIR Site 9 MCB Camp Pendleton, California

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PCE MCL 5.0 ug/L

This slide shows Site 9, the Former Waste Stabilization Pond, which was characterized for 8 years using traditional investigations (PA/RI/FS).

In 1993, a ROD for MNA and long-term monitoring was signed.

Since then, PCE concentrations in cross-gradient well have increased from near MCL to 97 ppb.

Additional sampling at Site 9 was conducted in 2002 to address data gaps and attempt to link Site 9 to PCE.

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Site Description� Located on base in undeveloped canyon

� Approximately 0.5 mile upgradient from non-beneficial use boundary

� Site used for Marine Corps training

� Endangered species habitat precludes future development

1994 Air Photo

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Working Conceptual Site Model

Conceptual Site Model

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Site 1114 Investigation� Four phases of investigation executed

within one Dynamic Work Plan / reporting cycle:

� Phase I � File and Records Review, Interviews

� Phase II � Lithologic and Groundwater Investigation

� Phase III � Focused Source Area Investigation

� Phase IV � Installation of Permanent Monitoring Wells

Distinguish between old phased approach and Triad approach proposed

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Triad at Site 1114

� Systematic Planning � Project end goals are the identification of the VOC source area and plume extent

� Dynamic Work Plan � Flexibility to determine sample locations and numbers in the field to meet project end goals and optimize CSM, as necessary.

� Real-Time Measurement Tools � SCAPS, CPT, mobile laboratory, MIP, EPA 8265.

Experienced technical field staff empowered to make decisions, and close communication with greater project team during work plan implementation.

Site Characterization and Penetrometer System

Membrane Interface Probe

Direct sampling ion trap mass spectrometer

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Project Objectives� Identify potential VOC source

areas� Target VOCs include PCE and

related degradation products TCE, DCE and VC

� Delineate area where VOCs exceed MCLs in groundwater

� Investigation conducted following U.S. EPA�s Triad approach with goal of streamlining sampling, analysis, and decision making

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� Obtained permits

� Utility clearance

� Conducted GPS survey of planned sample locations

� Constructed access roads to sample locations

� Set up FTP site for data communication

� Established field technical team (FTT)

Mobilization Tasks

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Project Personnel

CORE FFA TEAMBeatrice GriffeyRWQCB RPM Agency Point of Contact

Martin HausladenU.S. EPA RPM

Bill MabeyTech Law

Tayseer MahmoudDTSC RPM

Mark BonsavageMDBCP IR Branch Manager

Michael BilodeauSWDIV RPM

Patricia Underwood, PhDSWDIV RTM

Ed MirandaSWDIV RPM

Nars AncogSWDIV QAO

FIELD TECHNICAL TEAM

Geoff Buckner Registered Geologist

Karen CollinsProject Manager

Timothy ShieldsSCAPS Manager

Adrianne SaboyaPWC QA Manager

Bill Davis, PhDDSITMS Chemist

Fred EssigSCAPS Geologist

Bill HagenSCAPS Operator

Craig HaverstickPWC Health and Safety

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Phase I � File and Records Review, Interviews

� Compiled and reviewed available historical information on upgradient operations.� Archives of Base Historian

� Historical air photos

� Utility maps

� Site visits

� Interviews with key facility personnel

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Phase I � Preliminary Assessment1932 1953

� No history of industrial operations southwest of Stuart Mesa Road.

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Phase I � Preliminary Assessment1958 1993

� Development NE of road consists of barracks, NEX, fire station, medical/dental clinic, mess hall, training facilities, equipment storage areas.

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� Two areas of interest identified.� Tank maintenance

facility in 41 Area

� Equipment disassembly north of IR Site 9

Phase I � PA Investigation Results

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Phase I � PA Investigation Results

Tank Maintenance Facility

� West of Bldg. 41312� Military tanks serviced from mid-

1950s through 1990s. � Cleaning chemicals reportedly

used, type undetermined� No VOCs reported in

groundwater samples from UST wells at B41312

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Phase I � PA Investigation Results

Area North of IR Site 9� Rumored to have been used for equipment

disassembly� Specifically, hovercraft fuel tanks

reportedly dismantled in this area� Equipment parts not identified in site walks� No supporting facility, tools, or equipment

located in area � Geophysical survey yielded no anomalies

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Phase II � Lithologic and Groundwater Investigation

� Lithologic and groundwater quality data collected adjacent to and upgradient of 9W-07A

� CPT data collected at 12 locations provided continuous lithologic characterization

� Discrete groundwater samples collected from 12 temporary microwells at 10 locations.

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Phase II � Lithologic and Groundwater Investigation

� Three sampling transects initiated, radiating out- and up-gradient from 9W-07A

� Five locations problematic: roads to 4, 14, and 15 were impassable, and shallow refusal at 1 and 3 prohibited well construction.

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SCAPS CPT POINTS

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CPT Log CP1114-13

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Designing Well Screen

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Phase II � Groundwater Investigation

SCAPS Microwells� 12 temporary microwells constructed and

sampled at 10 locations� Each well constructed with a 5 foot screen� Groundwater samples analyzed by HP Labs

with detection limit of 1.0 ug/L� Target VOCs not detected in microwells 2,

5, 6, 7, 8, 10, 11A, 11B, and 12. � PCE and TCE reported in 13A and 13B.

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Temporary Microwell Data

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Geoprobe® Systems Membrane Interface Probe (MIP) � An inert ultrapure helium carrier gas is

sent down to the probe, sweeps behind the membrane, and returns to the surface to be analyzed.

� A temperature controller allows the membrane to be heated, which may optimize membrane performance.

� When the membrane is heated, VOCs advect away from the membrane. However, some of the VOCs pass through the membrane and are brought to the surface with the carrier gas to be analyzed.

� SCAPS analyzes the gas stream with a Direct Sample Ion Trap Mass Spectrometer (DSITMS)

Phase III � Focused Source Area Investigation

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MIP Probe

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Calibrating the system. � Samples of water containing a known concentration

of contaminant are added to sand in a calibration jig and measured with the MIP/DSITMS.

� The results are used to prepare a calibration curve.

Note that this calibration procedure assumes that the matrix will be fully saturated sand. Therefore, results from other matrices (such as unsaturated soils) need to be evaluated carefully for usability. Comparison sampling using traditional ex-situ laboratory analysis may be beneficial.

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Phase III � Source Area Investigation

SCAPS MIP� Thirteen SCAPS/MIP borings advanced� 12 sample locations positioned along three

transects upgradient from 9W-07A, southwest of Stuart Mesa Road

� 1 location northeast of Stuart Mesa Road near former tank maintenance facility by Bldg. 41312

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MIP Results

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Phase III � Source Area Investigation

SCAPS MIP� Over 690 linear feet

of site area assessed for VOCs

� MIP-11 was the single location where target VOCs were detected

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Conclusions

� Detailed conceptual site model produced identifying:� Site 1114 lithologic conditions� Well-delimited VOC presence

� Greatest PCE concentration was 1,000 ppb at MIP-11 between 42.5 and 44.4�bgs

� PCE concentration at MIP-11 declines sharply with depth, dropping order of magnitude within 2 feet

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Conclusions

� VOC source area is well bounded � Laterally within ~200 feet � Vertically within 10 feet� Groundwater samples from

microwells confirm vertical boundary

� DNAPL conditions and product-level concentrations were not encountered

� Data suggests small volume of initial release.

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Conclusions� No complete pathways linking PCE at Site 1114

with receptors� Site 1114 is overlain by protected habitat,

therefore not subject to development� Site is located ~1/2 mile upgradient from non-

beneficial use boundary� FFA team concurred that no further

characterization required� DoN recommending No Further Action; ROD

planned