United States
Environmental Protection
Agency
r/EPA
Office of Solid Waste and
Emergency Response
(5102G)
EPA-542-R-98-006
September 1998
www.epa.gov
clu-in.com
Innovations in
Characterization
Case Study: Hanscom Air Force Base,
Operable Unit 1 (Sites 1,2, and 3)
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EPA-542-R-98-006
September 1998
Innovations in Site Characterization
Case Study: Hanscom Air Force Base
Operable Unit 1 (Sites 1, 2, and 3)
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Technology Innovation Office
Washington, D.C. 20460
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Notice
This material has been funded wholly by the United States Environmental Protection Agency under
Contract Number 68-W7-0051. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
Copies of this report are available free of charge from the National Center for Environmental Protection
and Information (NCEPI), PO Box 42419, Cincinnati, Ohio 45242-2419; telephone (800) 490-9198 or
(513) 489-8190 (voice) or (513) 489-8695 (facsimile). Refer to document EPA-542-R-98-006,
Innovations in Site Characterization—Case Study: Hanscom Air Force Base, Operable Unit 1, Sites 1, 2,
and 3. This document can also be obtained through EPA's Clean Up Information (CLU-IN) System on the
World Wide Web at http://clu-in.com or by modem at (301) 589-8366. For assistance, call (301) 589-
8368.
Comments or questions about this report may be directed to the United States Environmental Protection
Agency, Technology Innovation Office (5102G), 401 M Street, SW, Washington, D.C. 20460; telephone
(703) 603-9910.
11
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Foreword
This case study is the first in a series designed to provide cost and performance information for innovative
tools that support less costly and more representative site characterization. These case studies will include
reports on new technologies as well as novel applications of familiar tools or processes. They are prepared
to offer operational experience and to further disseminate information about ways to improve the efficiency
of data collection at hazardous waste sites. The ultimate goal is enhancing the cost-effectiveness and
defensibility of decisions regarding the disposition of hazardous waste sites.
in
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Acknowledgments
This document was prepared for the United States Environmental Protection Agency's (EPA) Technology
Innovation Office. Special acknowledgment is given to EPA Region 1 (the Office of Site Remediation and
Restoration and the New England Regional Laboratory), Tufts University (Center for Field Analytical
Studies and Technology), and the staff of Hanscom Air Force Base for their thoughtful suggestions and
support in preparing this case study.
IV
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Table of Contents
Notice ii
Foreword iii
Acknowledgements iv
CASE STUDY ABSTRACT viii
TECHNOLOGY QUICK REFERENCE SHEETS ix
EXECUTIVE SUMMARY 1
SITE INFORMATION 3
Identifying Information 3
Background 3
Site Logistics/Contacts 4
MEDIA AND CONTAMINANTS 4
Matrix Identification 4
Site Geology/Stratigraphy 4
Contaminant Characterization 4
Matrix Characteristics Affecting Characterization Cost or Performance 4
SITE CHARACTERIZATION PROCESS 6
Goal of Site Characterization 6
Dynamic Workplan - Adaptive Sampling Strategy 6
Data Quality Objectives 8
CHARACTERIZATION TECHNOLOGIES 11
Sample Collection 11
Field Analytical Technologies 11
PERFORMANCE EVALUATION 13
Sample Collection 13
Sampling Results 13
Method Detection Limit (MDL) Studies 17
VOC Screening Method vs. VOC Quantitative Method 17
Instrument Calibration 18
Method Blanks 19
Precision 20
Accuracy 20
COST COMPARISON 23
OBSERVATIONS AND LESSONS LEARNED 25
Dynamic Workplans and Field Analytical Methods 25
Field Instrument and Method Performance 25
Mobile Laboratory Set-up and Operation 26
REFERENCES 28
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List of Figures
Figure 1: Site Location 1
Figure 2: Hanscom Field Sites 4
Figure 3: Cis-l,2-DCE Concentrations (in ppb) Above 4 Feet at FiAFB Site 1 14
Figure 4: Toluene Concentrations (in ppb) Below 8 Feet at F£AFB Site 2 15
Figure 5: Cadmium Concentrations (in ppb) at F£AFB Site 3 16
List of Tables
Table 1: Site-specific Action Levels, Quantitation Limits, and Method Detection Limits 6
Table 2: F£AFB Data Quality Objectives for Quantitative Analysis of Organics 9
Table 3: F£AFB Data Quality Objectives for Quantitative Analysis of Metal Analytes 9
Table 4: Agreement of Screening Results with Quantitative Analysis for VOCs 15
Table 5: Initial and Continuing Calibration Summary for VOCs 19
Table 6: Field versus Laboratory VOC Data Comparison 22
Table 7: Cost Comparison between Traditional and Dynamic Field Investigations 24
VI
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Case Study Abstract
Hanscom Air Force Base
Middlesex County, Massachusetts
Site Name and Location:
Hanscom Air Force Base
Middlesex County, Massachusetts
Period of Operation:
1941 -1973 Supported fighter
aircraft operations and maintenance;
Air Force Research & Development
Operable Unit:
#01 (Site 1 - Fire Training Area II;
Site 2 & 3 - Paint Waste Areas)
Sampling & Analytical
Technologies:
1. Geoprobe;
2. Bruker Thermal Desorption Probe
Head on Gas Chromatography/Mass
Spectrometer (Bruker TDGC/MS);
3. Tekmar Purge and Trap
Concentrator with Hewlett-Packard
GC/MS;
4. Ion Signature Technology's Thermal
Desorber with Hewlett-Packard
GC/MS (Tufts TDGC/MS);
5. Ion Signature Technology's Ion
Fingerprint Detection (IFD) Software
6. Field-rugged Inductively Coupled
Plasma/Optical Emission Spectrometer
(ICP/OES)
CERCLIS #
MA8570024424
Current Site Activities:
RI/FS complete, ground water pump and
treat operational May 1991, total flow 300
GPM. Focused Feasibility Study.
Point of Contact:
Robert Lim
US EPA - Region 1
J. F. Kennedy Federal Building
Boston, MA 02203-2211
(617)223-5521
http://clu-in.com/hanscom.htm.
Media and Contaminants:
Groundwater and soils at Hanscom Air
Force Base are contaminated with
chlorinated and aromatic solvents,
metals, and petroleum compounds.
Technology Demonstrator:
Tufts University, Chemistry Dept.
Center for Field Analytical Studies &
Technology
Medford, Massachusetts 02155
(617)627-3474
Number of Samples Analyzed during Investigation:
A 10-day Adaptive Sampling and Analysis Program produced the following: 601 soil samples screened for volatile organic
compounds (VOC) (<1 min/analysis); 158 soil samples for quantitative analysis for VOCs (15 mm/analysis); 69 soil samples
for simultaneous quantitative analysis of poly chlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs);
121 quantitative soil samples for metals (8 min/analysis after microwave sample digestion).
Cost Savings:
The cost savings using this approach are estimated at 50% over traditional methods.
Results:
Field analytical methods can provide quantitative data to support remedial decisions for contaminated soil. The assessment of
contaminated soil was completed in two weeks using an Adaptive Sampling and Analysis Strategy.
Description:
As part of EPA's Environmental Technology Initiative (ETI), Tufts University conducted a demonstration of the ability of
field analytical methods to produce data of sufficient quality to support a risk assessment. The specific risk scenario was soil
contamination migration to ground water. Action limits were set at the 20 Dilution-Attenuation Factor (DAF) from EPA's
Soil Screening Levels. Over a two week period, subsurface soil cores and samples were collected using a Geoprobe. Soil
samples were screened with the Bruker Thermal Desorption GC/MS at an average rate of 75 samples/day. Quantitative VOC
analyses were performed using conventional (Tekmar) Purge & Trap GC/MS in conjunction with Tufts-developed IFD
software to speed processing of the MS signal and data analysis. After extraction, simultaneous quantitative PAH/PCB
analyses were performed by Tufts-developed Thermal Desorber GC/MS and IFD data analysis producing data with only a 10-
minute run time. Finally, fixed-lab quality data for metals was produced in the field by the use of batched microwave
digestion and a field-adapted ICP/OES.
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TECHNOLOGY QUICK REFERENCE SHEET
Case Study Name: Hanscom Air Force Base, Sites 1, 2, and 3
Technology: Geoprobe®
Summary of Case Study's Performance Information
Project Role:
Collect soil borings
Cost/Performance Information: $16,500 for 8 days. During that time 61 pushes (1016
linear feet) were made, and 601 screening samples (soils) were collected.
Total Cost: $16,500 (subcontracted)
Project Cost Breakdown
Instrument Cost:
Included in subcontract
Consumables Cost:
Disposable cellulose
sleeves: $1 per foot
Labor Cost:
Included in subcontract
Waste Disposal Cost:
Information not available
Site-Specific Performance Observed:
1016 linear feet collected. Performance generally satisfactory. Due to the sandy nature of the soil, soil samples could not be
retained within Geoprobe sleeve when collection of soil from below the water table was attempted.
At Site 1, the geology limited the sampling depth to 15-20 feet because the Geoprobe was unable to push through the till
layer to reach bedrock. Subsurface materials in others areas consisted of sandy fill material and no hindrance was found in
those areas. A total of 61 pushes were performed.
General Commercial Information (Information valid as of August 1998)
Vendor Contact:
1-800-GEOPROBE
www.geoprobesystems.com
Vendor Information:
Geoprobe® Systems
601 N. Broadway
Salina, KS 67401
Limitations on Performance:
Bedrock drilling; vehicle access to site; and depths >100ft.
[Information provided by vendor]
Availability/Rates:
Rent $1,000 to $2,000/day
Principle of Operation: Direct push soil probing
equipment
Power Requirements:
Vehicle or auxiliary engine
General Performance Information
Rate of Throughput: push up to 200 ft/day
Known or Potential Interferences:
Bedrock
Applicable
Media/Matrices: Soil,
ground water, and soil gas
sampling
Wastes Generated
Requiring Special
Disposal: Limited soil
cuttings
Analytes Measurable with
Commonly Achieved Detection
Limit Ranges:
Depends on the specific probe or
accessory used
Other General Accuracy/Precision Information:
Depends on the specific probe or accessory used
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TECHNOLOGY QUICK REFERENCE SHEET
Case Study Name: Hanscom Air Force Base, Sites 1, 2, and 3
Technology: Broker Thermal Desorption Probe Head on Gas Chromatograph/Mass Spectrometer (TDGC/MS)
Summary of Case Study's Performance Information
Project Role: Screen for VOCs using direct measuring mode
Detections flagged screening interval for quantitative analysis.
Total Cost:
Estimated as 601 screening samples x $33 = $19,833
Analytical Information Provided: Positive or
negative screening result for VOCs.
Cost Per Sample:
Estimated at $33 per screening result.
Project Cost Breakdown
Instrument Cost: 3 week rental-
$12,500/3 weeks (incl. GC/MS)
Consumables Cost:
Information not available
Labor Cost:
Information not available
Site-Specific Accuracy/Precision Achieved:
Since this technology was used as a screening device, typical precision and accuracy
evaluations were not performed. However, the use of a daily standard ensured sensitivity
to 10 ppb for 1 1 target VOC compounds. Additionally, comparison of the screening results
from this instrument with confirmatory quantitative analyses found 90% agreement, 4%
false positives, and 6% false negatives when results were compared at the 10DAF
quantitation limit (which was !/2 of the 20DAF action level).
Waste Disposal Cost:
Information not available
Throughput Achieved:
Less than 1 minute/screening
sample; 75 samples/day;
601 samples total.
Turn-around time: results
available immediately
General Commercial Information (Information valid as of August 1998)
Vendor Contact:
978-667-9580
www.bruker. com
Availability/Rates :
$185,000 purchase price
Power Requirements:
500 W
Vendor Information:
Bruker Analytical Systems,
Inc.
19 Fortune Drive
Manning Park
Billerica,MA01821
Limitations on Performance:
Maximum temperature 240 °C with air, 300 °C with
nitrogen. Extremely polar molecules cannot be
analyzed with the same sensitivity.
Principle of Operation: Used for rapid screening
of Geoprobe cores for VOCs. TD probe head placed
over small access holes cut into the cellulose sleeves at
1-ft. intervals. Soil under the probe head is heated and
VOCs are swept into the GC/MS for analysis in the
SIM mode.
Instrument Weight and/or
Footprint:
65kg
750x450x350 mm
General Performance Information
Known or Potential Interferences: Excessive water vapor or high levels of contamination
Applicable Media/Matrices:
Soil gas and soil
Wastes Generated
Requiring Special Disposal:
None
Analytes Measurable w
Expected Detection Lim
Other Analytical Perfoi
Information:
VOCs (ppb range), SVOCs
detection range)
ith Other General Accuracy/Precision
tits or Information:
•mance Accuracy consistent within 30% of the
reference concentrations; precision (as
(variable determined by RPD on duplicate samples) less
than 30% [Information supplied by vendor]
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TECHNOLOGY QUICK REFERENCE SHEET
Case Study Name: Hanscom Air Force Base, Sites 1, 2, and 3
Technology: Tekmar 3000 Purge and Trap Concentrator (with Hewlett-Packard 5890 III 5972 GC/MS)
Summary of Case Study's Performance Information
Project Role:
Quantitative analysis of VOCs
Total Cost: Estimated as 158 samples x $100 = $15,800
Analytical Information Provided:
18 VOC analytes quantitated.
Cost Per Sample: Estimated at $100 per sample.
Project Cost Breakdown
Instrument Cost:
Rental- $2,700 for 3
weeks
Consumables Cost:
Information not available
Labor Cost:
Included in cost per sample (above)
Site-Specific Accuracy/Precision Achieved:
Precision was to be evaluated by replicate analysis of 8 site soil samples, however, the
samples selected for replicate analysis had very low concentrations of target compounds.
Accuracy was assessed by the recovery of 2 surrogate compounds added to each sample. The
average recovery (for both surrogate compounds and over 158 samples) was 132%. 82% of
surrogate recoveries fell between 30-200%.
Waste Disposal Cost:
Information not available
Throughput Achieved:
15-20 minutes/sample;
158 samples total.
Turn-around time: results
available by or before the
next day
General Commercial Information (Information valid as of August 1998)
Vendor Contact:
800-543-4461
www.tekmar.com
Availability/Rates:
Purchase P&T-- approx.
$12,000, including
software & installation
Vendor Information:
Tekmar-Dohrmann
P.O. Box 429576
Cincinnati, OH 45249
Principle of Operation: Purges
volatiles from water or soil onto a
sorbent trap which is then heated and
the analytes are swept into the GC
column.
General Performance Information
Limitations on Performance:
Performs in temperatures up to an environmental
temperature of 40 °C; sample temperature of
200 °C; humidity 10-90%
Power
Requirements:
500 W
Instrument Weight
and/or Footprint:
Purge and Trap - 37 Ibs.
Known or Potential Interferences: Excessive water vapor (moisture control system set up in instrument)
Applicable
Media/Matrices:
Water and soil
Analytes Measurable with Expected
Detection Limits or Other Analytics
Performance Information:
VOCs (ppb range)
SVOCs (variable detection range: low
molecular weight compounds are more lik
to be volatized than high molecular weigh
compounds)
Turn-around time: results available
immediately
Other General Accuracy/Precision
il Information: Not available
ely
^ Wastes Generated Requiring Special
Disposal: Depends on sample; some semi-
volatiles may remain in sample and require
special disposal procedures
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TECHNOLOGY QUICK REFERENCE SHEET
Case Study Name: Hanscom Air Force Base, Sites 1, 2, and 3
Technology: Thermal Desorber with Hewlett-Packard Gas Chromatography/Mass Spectrometry (TDGC/MS)
Summary of Case Study's Performance Information
Project Role:
Quantitative analysis of
PAH/PCBs
Analytical Information Provided:
22 analytes: 16 PAHs (6 as PAH pairs) + 9 PCB chlorination levels (summed to estimate the
sample's total PCB concentration).
Total Cost: Estimated as 69 samples x $100 = $6,900
Cost Per Sample: Estimated at $100 per sample.
Project Cost Breakdown
Instrument Cost:
Information not available
Consumables Cost:
Information not available
Labor Cost: Included
in cost per sample
Site-Specific Accuracy/Precision Achieved: Because there were few detections of
PAH/PCBs in site samples, precision was estimated from the initial (ICV) and continuing
calibration verifications (CCV): A total of 8 ICVs & CCVs were run. Of the 176
analytical results (8 runs X 22 analytes per run), 80% had %D < 30%, 14% between 30-
40% and 6% had %D > 40%.
Accuracy was assessed by the recovery of a surrogate compound added to each sample.
The average recovery over 69 samples was 94%, and 92% of the surrogate recoveries fell
between 30-200%.
Waste Disposal Cost:
Information not available
Throughput Achieved:
Sample prep time: 1 hr/batch of
20 samples; Analysis time: 10
minute/sample; 69 samples total
analyzed
General Commercial Information (Information valid as of August 1998)
Vendor Contact:
Tel: 617-876-0333
Fax: 617-876-0777
ygankin@ionsigtech.com
Availability/Rates:
Purchase Thermal
Desorber -$15,000
Vendor Information:
Dr. Yuriy Gankin
Ion Signature Technology, Inc.
P.O. Box 636
Cambridge, MA 02238
Limitations on Performance:
GC: 0-55 °C; 5-95% humidity; Carrier gas, minimum
purity of 99.9995%
MS: 15-35C; Humidity (non-condensing) 25-50% RH
Principle of Analytical Power Requirements:
Operation: Ballistic GC - 120/200V, 220/240V;
heating allows for a large 47. 5-66 Hz
volume injection of sample MS - 99-127V or 198-
(1 to 1000(11) or for thermal 254V; 48-66 Hz
desorption of a sorbent trap.
Instrument Weight and/or
Footprint:
GC/MS - 133 Ibs, 46.5cm x
77cm x 66cm; the Thermal
Desorber sits inside the GC
injection port
General Performance Information
Known or Potential Interferences: moisture, oxygen (traps recommended)
Applicable
Media/Matrices:
Soil, Soil gas, Water
Wastes Generated
Requiring Special
Disposal: None
Analytes Measurable with
Expected Detection
Limits: VOCs and SVOCs
(ppb range);
Turn-around time: results
available by or before the next
day
Other General Accuracy/Precision Information:
High concentrations: RPD<60%;
Low concentrations: RPD<100%
Rate of Throughput: 10 minutes/sample for quantitative
results; less time for screening result
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TECHNOLOGY QUICK REFERENCE SHEET
Case Study Name: Hanscom Air Force Base, Sites 1, 2, and 3
Technology: Inductively Coupled Plasma/Optical Emission Spectrometer (ICP/OES)
Summary of Case Study's Performance Information
Project Role: Quantitative analysis of Cd
and Pb; sample preparation performed by
microwave digestion
Analytical Information Provided: 22 inorganic analytes quantitated.
Cd and Pb were the only target inorganic analytes for the project; the other
20 analytes were coincidental.
Total Cost: Estimated as 121 samples x $275 = $33,275
Cost Per Sample: Estimated at $275 per sample.
Project Cost Breakdown
Instrument Cost:
Information not available
Consumables Cost:
$3,000
Labor Cost: Included in
cost per sample (above)
Waste Disposal Cost:
Information not available
Site-Specific Accuracy/Precision Achieved:
Precision was evaluated by triplicate analysis of 9 site soil samples. 89%
of target analyte detections had RSDs less than 30%. 88% of all analyte
detections in the 9 replicates had RSDs less than 30%.
Accuracy was assessed by laboratory control standards, which were run
a total of 21 times. All target analyte recoveries fell within 80-120% of
the certified values for the standards.
Throughput Achieved:
Sample prep time: 1.5 hr/batch of 20 samples;
Analysis time: 8 min/ sample; 121 samples total
Turn-around time: results available by or before
the next day
General Commercial Information (Information valid as of August 1998)
Vendor Contact:
603-886-8400
www.leemanlabs.com
Vendor Information:
Leeman Labs
6 Wentworth Drive
Hudson, NH 03 051
Limitations on Performance:
Environmental temperature 60-86F0; Humidity
20-80% (non-condensing); Argon gas should be
99.995% pure; 80-90 psi
Principle of Operation:
Sample is neubilized and
heated by the plasma. The
excited atoms and ions produce
line spectra.
Power Requirements:
ICP/OES 110 V, 20 amp; 240 V,
30 amp
Water circulator 115V, 15 amp,
60 Hz
Instrument Weight and/or Footprint:
ICP/OES: 375 Ibs, 54x30x35 (in.)
Power supply: 175 Ibs, 18 cu. in.
Water circulator: 50 Ibs, 22x12x22 (in.)
Known or Potential Interferences: Excessive water vapor
Applicable Media/Matrices:
Water and soil
Wastes Generated Requiring Special
Disposal: Depends on sample composition
and TCLP results of waste analysis
Analytes Measurable with
Expected Detection Limits or Other
Analytical Performance
Information: Inorganics
(ppb to ppm range, depending on the
analyte and sample preparation method)
Other General
Accuracy/Precision
Information: Not available
Rate of Throughput:
Depends on how many metals
analyzed, and if autosampler is
used
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TECHNOLOGY QUICK REFERENCE SHEET
Case Study Name: Hanscom Air Force Base, Sites 1, 2, and 3
Technology: Ion Fingerprint Detection (IFD)™ Software
Summary of Case Study's Performance Information
Project Role: Supports
component identification in MS
analysis
Cost Per Sample: Use of the software reduced GC/MS run times by a factor of 2-4,
which increased sample throughput, and thus decreased both direct costs (e.g., labor) and
indirect costs (by decreasing turn-around time of results within the context of a dynamic
workplan).
Project Cost: $20,000 for 2 weeks usage (labor included)
Site-Specific Accuracy/Precision Achieved:
The performance of the IFD software was compared with the data processing software
typically supplied with an HP GC/MS system. Of the 158 VOC samples analyzed, 4 samples
required re-analysis by IFD to resolve interference or linearity issues, compared to 25 re-
analyses required using the traditional software package.
The GC/MS total ion current chromatograms from 205 detections of organic compounds
were processed by both software systems. For each detection, the quantitative results
computed by each software system were compared by calculating the difference between the
2 results. Of the 205 detections, 85% had RPDs < 50% and 65% had RPDs < 20%.
Internal standard data can also be used to assess software performance. The internal standard
signal was within the ±50% difference acceptance range 85% of the time for the IFD
software, compared to 78% for the other software.
Throughput Achieved:
Quantitative organic analysis
by GC/MS performed with
runtimes of 10
minutes/sample.
General Commercial Information (Information valid as of August 1998)
Vendor Contact:
Tel: 617-876-0333
Fax: 617-876-0777
ygankin@ionsigtech.com
Availability/Rates:
$10,000 per copy (1-4 copies)
$7,500 per copy (>4 copies)
Vendor Information: Limitations on
Dr. Yuriy Gankin Performance:
Ion Signature Technology, Inc. None specified
P.O. Box 636
Cambridge, MA 02238
Rate of Throughput: 10
minutes GC run time for
quantitative results; less time
for screening results
Principle of Analytical Operation: Complete data analysis system for mass
spectrometers, with complete report writing capability. The software uses mathematical
algorithms to identify target compounds by deconvoluting their ion signals from non-
uniform background interference signals contributed to the total ion current. IFD
accurately identifies and quantifies target compounds in the presence of high levels of
interferences and with minimal chromatographic separation.
Software Performance Information
The IFD software is capable of identifying low concentrations of target analytes in the presence of high levels of matrix
interferences. By "seeing through" the matrix interferences, the software reduces the need for sample re-analysis and
dilution, and increases confidence in surrogate, internal standard, and target compound identification and quantification.
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Hanscom Air Force Base
^5 EXECUTIVE SUMMARY ^^^^^^^^^^^^^^^^^^^M
Field analytical instrumentation and methods were used to support a site characterization study at the
Airfield at Hanscom Air Force Base (F£AFB) Operable Unit 1. F£AFB is located in Middlesex County,
Massachusetts, and occupies land in the towns of Bedford, Concord, Lexington, and Lincoln. U.S. Air
Force military operations began in 1941 and continued through 1973. With the cessation of military flying
activities in 1973, the airfield and the surrounding land was given to the Massachusetts Port Authority
(MASSPORT), which currently operates a civilian airport as L.G. Hanscom Field. The U.S. Air Force
continues to occupy 396 acres and operates the Electronic Systems Division of the Air Force Systems
Command at HAFB.
As part of EPA's Environmental Technology Initiative (ETI), a demonstration of a dynamic site
investigation using an Adaptive Sampling and Analysis Program was utilized at HAFB for Operable Unit
1. The goal of the HAFB investigation was to demonstrate the ability of field analytical methods to
produce data of sufficient quality to support remedial decisions. The specific project objectives used the
EPA Soil Screening Level action limits to determine if residual soil contamination posed a risk via the soil
to ground water pathway [5]. The HAFB investigation relied on data produced in the field to make
decisions as to the location of samples collected and the types of analysis performed. When compared with
the traditional site characterization process, the dynamic workplan/adaptive sampling and analysis program
for HAFB resulted in a faster and cheaper site investigation. The adaptive sampling and analysis program
provided information on a "real-time" basis to support on-site decision making. The field methods were
"performance based" and provided data of sufficient quality to achieve site-specific data quality objectives
(DQOs), with sample analysis rates that supported the dynamic site investigation process.
Innovative sampling and analytical technologies used at HAFB include Geoprobe; Bruker Thermal
Desorption Gas Chromatography/Mass Spectrometry (TDGC/MS); Tekmar Purge and Trap with a
Hewlett-Packard (HP) GC/MS; a Tufts designed thermal desorber inlet and HP GC/MS (TDGC/MS); and
Ion Fingerprint Detection (IFD) software, as well as an on-site laboratory field rugged ICP/OES. During
the HAFB investigation, an average of 75 soil samples per day were screened for volatile organic
compounds (VOCs) by the Bruker TDGC/MS. In a two-week period, a total of 601 samples were
analyzed. Quantitative VOC analysis of 158 soil samples by the Tekmar purge and trap GC/MS was made
to confirm the screening results and to delineate the extent of contamination. Quantitative analyses of 69
soil samples for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were
performed by the Tufts TDGC/MS and 121 soil samples for metals were performed by the ICP/OES.
Some important observations and lessons learned during the project were the following:
Field analytical methods employing performance-based methods can produce data of equal quality to
commercial laboratories employing standardized EPA methods, can support a dynamic workplan/adaptive
sampling and analysis program, and can support cleanup verification programs.
Cost effectiveness is maximized when site DQOs, analytical throughput rates, data turnaround times,
sample collection rates, and sample analysis costs are evaluated and optimized to meet the site-specific
scientific and engineering questions under investigation prior to the beginning of the field work.
TDGC/MS and the mass spectrometry data analysis algorithms allow PCB/PAH analyses to be performed
at the same time without the need for sample cleanup and fractionation time. Analytical run times can be
reduced from 40 minutes to 10 minutes.
DQOs were met for all target compounds except vinyl chloride. Trade-offs may need to be considered
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^^^ Hanscom Air Force Base
^S EXECUTIVE SUMMARY ^^^^^^^^^^^^^^^^^^^^m
between achieving low limits of detection for VOC gaseous compounds and meeting DQOs for all other
(less volatile) VOC target compounds.
A full copy of the report on which this case study is based, "A Dynamic Site Investigation Adaptive
Sampling and Analysis Program for Operable Unit 1 at Hanscom Air Force Base Bedford, Massachusetts"
can be downloaded off of the Internet at http://clu-in.com/hanscom.htm.
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Hanscom Air Force Base
SITE INFORMATION ^^^^^^^^^^^^^^^^^^^^^S
Identifying Information
Hanscom Air Force Base (HAFB)
Middlesex County, Massachusetts
Operable Unit: 1 (Sites 1, 2, and 3)
CERCLIS#: MA8570024424
Action Memorandum Date: 8/2/96
ROD Date: N/A
Background [1]
Physical Description: The F£AFB site is located in eastern Massachusetts in the towns of Bedford,
Concord, Lexington, and Lincoln, see Figure 1. F£AFB is approximately fourteen miles northwest
of downtown Boston. Although F£AFB covers a total of 396 acres, the combined areas of interest
in this study total only 20 acres. Operable Unit 1 consists of three sites: Site 1 is situated on the
side of a hill, that falls rapidly toward the southeast where the land levels off. Site 2 is located
approximately 2,000 feet to the southeast of Site 1, and is situated in a level plain area. Site 3 is
located approximately 4,000 feet to the southwest of Sites 1 and 2, and is situated in the same plain
as Site 2.
Site Use: From 1941 to 1973 FiAFB's primary mission was the support of fighter aircraft
operations and maintenance and the support of Air Force Research and Development (R&D).
Thereafter, F£AFB no longer provided fighter aircraft maintenance and began to support Air Force
Command, Control, Communications, and Intelligence activities. The State of Massachusetts
obtained control of the airfield in 1974 and renamed it the L.G. Hanscom Field. The airfield is
currently operated by the Massachusetts Port Authority (MASSPORT) as a civilian airport.
Except for the airfield, the remainder of the base was retained by the Air Force.
Release/Investigation History: Site
1 was used as a fire training area ^\ Hansoom Air Force Ba«
where waste oils, flammables, aircraft , __ ^ \ m^osex Comty'MA
wreckage, and fuselages were burned.
Sites 2 and 3 are areas where 50-
gallon drums containing waste
solvents, fuels, and paints were
buried. Hazardous waste site
investigations for Operable Unit 1
(Sites 1, 2, and 3) began at Hanscom
Field in 1982, see Figure 2. In 1987
and 1988, HAFB undertook a
removal action that excavated visibly
contaminated soils and removed
drums from the sites. Approximately
4100 tons of contaminated soil and
more than 300 drums were removed Figure 1: Site Location
from the three sites and sent to an off-
site landfill.
Regulatory Context: HAFB and L.G. Hanscom Field were added to the National Priorities List in
1994. A Human Health and Ecological Risk Assessment and Feasibility Study for the airfield is in
-------
SITE INFORMATION
Hanscom Air Force Base
progress.
Site Logistics/Contacts
Federal Lead Agency: U.S. Air Force
Federal Oversight Agency: EPA
Remedial Project Manager:
Mr. Robert Lim
US EPA - Region 1
J.F. Kennedy Federal Building
Boston, MA 02203-2211
(617)223-5521
Quality Assurance Chemist:
Dr. Nora Conlon
USEPA - Region 1
60 West View
Lexington, MA 02173
(781)860-4335
HAFB Contact:
Mr. Tom Best
Environmental Engineer - USAF
66 SPTG/CEVR
Hanscom AFB, MA 01731-1910
(781)377-4495
•MEDIA AND CONTAMINANTS
Matrix Identification [11
Technology Demonstrator:
Dr. A. Robbat, Jr.
Tufts University, Chemistry Department
Center for Field Analytical Studies &
Technology
Medford, MA 02155
(617) 627-3474
ETI Project Officer:
Mr. John Smaldone
US EPA - Region 1
J.F. Kennedy Federal Building
Boston, MA 02203-2211
(617)223-5519
Type of Matrix Sampled and Analyzed: Subsurface soil
Site Geology/Stratigraphy [21
Much of F£AFB Airfield is built on man-made fill, and Sites 2 and 3 have been converted into
recharge pits for the ground water treatment system. The natural geologic setting includes
approximately seven feet of sandy fill overlying the topsoil and natural peat deposits that are
laterally discontinuous at the west end of the Airfield. North of Pine Hill, five to six feet of sand
and silt fill overlies glacial fill. Similar conditions were revealed east of Hartwell's hill, where three
feet of fill overlie swamp material. The fill material present in the area of the base consists
primarily of natural sand and silt.
Contaminant Characterization [11
Primary Contaminant Groups: The primary contaminant groups at HAFB are volatile organic
compounds (VOCs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs),
and metals.
Matrix Characteristics Affecting Characterization Cost or Performance
None
-------
I MEDIA AND CONTAMINANTS
Hanscom Air Force Base
S H.
I*, f-'
If
1:6 i
J& I
I1? II
3 I
I?
t'!
»3 f
;i?
!»il 1?
il al
I
Figure 2: Hanscom Field Sites
-------
Hanscom Air Force Base
I SITE CHARACTERIZATION PROCESS ^^^^^^^^^^^^^H
Goal of Site Characterization [1,3, 4]
The goal of the Environmental Technology Initiative (ETI) project at HAFB was to demonstrate the
capability of field analytical technologies in the context of producing data of sufficient quality to
support remedial decisions in a cost-effective manner in the vadose zone at Sites 1, 2 and 3. The
specific risk scenario was the threat of ground water contamination via the soil to ground water
pathway. The action levels were set at the 20 Dilution Attenuation Factor (DAF) from EPA's Soil
Screening Levels [5].
Dynamic Workplan - Adaptive Sampling Strategy [1]
The sampling and analysis program at F£AFB was based on a dynamic workplan in which the
program itself relied on field analytical instrumentation and methods to generate on-site information
on the nature, extent, concentration, and rate of movement of the contamination present at the site.
Rather than dictate the details of the sample analyses to be performed, the numbers of samples to be
collected, and the location of each sample in the sampling plan, the dynamic workplan specified an
initial set of sampling locations at which samples would be collected and analyzed using screening
analytical technology. A data quality objective approach then was used to establish the conditions
under which additional samples would be collected, and quantitative analyses performed. Adaptive
sampling and analysis programs are intended to change or adapt based on the analytical results
produced in the field.
The dynamic workplan used at F£AFB included the following six steps:
Step 1: Select the core technical team whose responsibility it is to prepare and carry out the
dynamic workplan. The core technical team included staff from F£AFB and the Air Force's
contractor CH2M Hill, EPA Region I and their contractor Camp Dresser & McKee (COM),
the Massachusetts Department of Environmental Protection (MA DEP), and Tufts
University. The core technical team included project managers, risk assessors,
hydrogeologists, and quality assurance chemists.
Step 2: Develop the Initial Conceptual Model and Decision Making Framework. The model
contained the best-available information at the start of the project and evolved as field
data were produced. Decision making was shared among certain team members. F£AFB
staff were responsible for sampling decisions, and Tufts staff were responsible for
analytical decisions.
Step 3: Develop Standard Operating Procedures (SOPs). SOPs for sample collection and
analysis were produced by the core technical team and approved by EPA before field
activities were initiated. The field methods were "performance based" and provided
data of sufficient quality to achieve site-specific Data Quality Objectives (DQOs), with
sample analysis rates that supported the dynamic site investigation process.
Step 4: Develop Data Management Plan. Data integration, sampling, and analysis
protocols were incorporated into an overall data management plan. Site maps were
prepared using Site Planner™ software depicting current information on
contamination levels. The maps were used to inform daily operations and the
selection of additional sampling locations.
-------
Hanscom Air Force Base
I SITE CHARACTERIZATION PROCESS
Step 5: Developed Quality Assurance Project Plan (QAPP). The QAPP defined the
responsibility of the technical team and regulators. It described the procedures to
be used to monitor conformance with, or documentation and justification of
departure from, the SOPs.
Step 6: Prepare Health and Safety Plan. A health and safety plan was produced and
included DQOs for the field analytical tools used to monitor worker and
community safety.
The team carried out a dynamic site investigation at Operable Unit 1 using the workplan discussed
above. In order to effectively implement the sampling strategy, sampling was conducted in rounds.
Rounds 1 and 2 were pre-specified in the dynamic workplan and collected concurrently. Round 3
sampling was to be conducted when the results from Rounds 1 or 2 indicated the need for additional
samples to adequately identify the spatial distribution of contamination. Round 3 sampling
occurred only at Site 1.
The study objectives included the use of field analytical technologies to produce data capable of
supporting a risk assessment of threats to ground water from soil contamination. To establish the
maximum levels of contamination that could remain in place and not pose a threat to ground water
quality, or to ground water users, the DAFs contained in EPA's Soil Screening Guidance [5] were
evaluated. The 20DAF values were selected by EPA as meeting the protective criteria and were
established as the action levels for determining the need for an action. The quantitation limits were
established at one-half the action level values (i.e. 1A x 20DAF = 10DAF) to insure that action levels
could be quantitated by the field analytical technologies. For convenience, the 10DAF values were
used to produce the site maps. The site-specific action levels (i.e. 20DAF), quantitation limits (QL),
and method detection limits (MDL) for the compounds of interest are shown in Table 1.
Table 1: Site-specific Action Levels, Quantitation Limits, and Method Detection Limits
Compound
Acenaphthene
Acenaphthylene
'Anthracene
Benzene
2Benz(a)anthracene
3Benzo(b)fluoranthene
3Benzo(k)fluoranthene
Benzo(a)pyrene
Cadmium
Carbon Tetrachloride
Chlorobenzene
Chloroform
2Chrysene
Dibenz(a,h)anthracene
1 , 1 -Dichloroethane
1 .2-Dichloroethane
Action Level
20DAF
(mg/kg)
570
570
12,000
0.03
2
5
490
8
8
0.07
1
0.6
1600
2
23
0.02
QL
10DAF
(mg/kg)
285
285
6,000
0.015
1
2.5
245
4
4
0.035
0.5
0.3
800
1
11.5
0.01
MDL
(mg/kg)
0.1
0.1
0.2
0.003
0.2
0.3
0.3
0.1
0.11
0.004
0.008
0.008
0.2
0.2
0.006
0.013
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Hanscom Air Force Base
I SITE CHARACTERIZATION PROCESS
Table 1: Site-specific Action Levels, Quantitation Limits, and Method Detection Limits
(continued)
Compound
1 . 1 -Dichloroethene
cis- 1 .2-Dichloroethene
trans- 1 .2-Dichloroethene
Ethvlbenzene
Fluoranthene
Indeno( 1 .2.3 -ccDpvrene
Lead
Naphthalene
^henanthrene
Pvrene
Total PCBs
Stvrene
Tetrachloroethene
Toluene
1.1.1 -Trichloroethane
Vinvl Chloride
4m-Xvlene
o-Xvlene
4p-Xylene
Action Level
20DAF
(mg/kg)
0.06
0.4
0.7
13
43.000
14
400
84
NA
42.000
NA
4
0.06
12
2
0.01
210
190
200
QL
10DAF
(mg/kg)
0.03
0.2
0.35
6.5
21.500
7
200
42
280
21.000
0.5
2
0.03
6
1
0.005
105
95
100
MDL
(mg/kg)
0.003
0.005
0.006
0.006
0.1
0.2
1.65
0.4
0.2
0.1
0.2
0.006
0.006
0.010
0.008
0.033
0.016
0.003
0.016
Notes: Organics with the same superscript co-elute. EPA has not established a 20 DAF for total PCBs [5], therefore,
the site-specific quantitation limit was set as 0.5-mg/kg. No 20DAF concentration was available for lead. One-half of
the screening level of 400-mg/kg for ingestion was used based on the Revised Interim Soil Lead Guidance for
CERCLA Sites and RCRA Corrective Action Facilities [6].
Source: [1]
Data Quality Objectives [1]
The HAFB site-specific data quality objectives were established to provide data of sufficient
quality to support the study objectives. Just before mobilization, the core technical team held its
final field investigation planning session at Tufts University. Details of the site investigation
objectives, sample collection process, field analyses to be performed, and the framework for
making decisions in the field were finalized. HAFB staff assumed primary responsibility for
directing the sample collection effort. When questions were raised concerning measured
contaminant concentrations at the action level, EPA provided guidance to determine whether
additional sampling was required. The work performed was conducted under an EPA-approved
workplan. The EPA conducted laboratory audits, reviewed SOPs and MDL studies, and verified
the data. Staff from Tufts and CH2MHill prepared chain-of-custody forms and logged information
about the samples. Tufts prepared samples for field and off-site laboratory analysis, while
CffiMHill was responsible for shipping samples to the off-site laboratory. Field analysis for
organics and metals was provided by Tufts, while Spectrum Analytical (Agawam, MA) performed
the off-site laboratory analysis.
-------
Hanscom Air Force Base
I SITE CHARACTERIZATION PROCESS
To ensure the data quality of the field analytical measurements, the project team developed data
quality objectives for organic analyses and inorganic analyses. The data quality objectives are
shown in Tables 2 and 3 below.
Table 2: HAFB Data Quality Objectives for Quantitative Analysis of Organics
Data Quality Parameter
Data Quality Objective
Initial Calibration:
Five-point calibration
Percent Relative Standard Deviation (%RSD) of average response
factor (RF): +/- 30% for 2/3 and +/- 40% for remaining 1/3 target
compounds
Continuing RF Calibration:
Beginning and end of day
+/- 30% difference between average RF and daily RF from
continuing calibration verification (CCV) for 2/3 and +/- 40%
difference for remaining 1/3 of target compounds
Method Blank:
Beginning and end of day or
after analysis of highly
contaminated sample
No more than four target compounds with concentrations detected
at greater than three times the quantitation limit.
Measurement Precision:
Duplicate or triplicates every
20th sample
When detected concentrations are greater than five times the
quantitation limit: Relative Percent Difference (RPD) must be less
than 60%.
When detected concentrations are less than five times the
quantitation limit: RPD must be less than 100% .
Measurement Accuracy:
1) Surrogate fortified samples
2) Field versus laboratory
comparison
1) The RPD between known surrogate value and results of
surrogate analysis must fall between 30% and 200%
2) When detected concentrations are greater than five times the
quantitation limit: RPD must be less than 60%
When detected concentrations are less than five times the
quantitation limit: RPD must be less than 100%
Source: [1]
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Hanscom Air Force Base
I SITE CHARACTERIZATION PROCESS
Table 3: HAFB Data Quality Objectives for Metal Analytes
Data Quality Parameter
Initial Calibration:
Two-point calibration, a blank and one
known high-level concentration
Continuing Calibration Verification: everv 10th
sample
Instrument Blank: everv 10th sample
Method Blank: everv 20th sample
Measurement Precision: duplicate everv 20th
sample
Measurement Accuracy:
1) Laboratory control check samples (ERA
soil and solution) analyzed every 20th
sample
2) Field versus laboratory
Data Quality Objective
Requirement
Average of three solutions
Percent recovery
+/- 20%
Concentration below reporting limit
Concentration below reporting limit
+/- 25% RPD
1) Percent recovery +/- 20%
2) a) +/- 60% RPD and
b) 50% < R < 200%where
R= 100 x Con.site/Coff.site
Source: [1]
10
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Hanscom Air Force Base
• CHARACTERIZATION TECHNOLOGIES ^^^^^^^^^^^^S
Sample Collection [1]
Geoprobe™ push technology was used to collect soil samples in 4-ft plastic sleeves. Samples were
taken in continuous increments in and around each fire training and drum burial pit, from the land
surface to the ground water table. Additional samples were taken based on the screening and
quantitative results obtained as follows:
• If Gas Chromatography/Mass Spectrometry (GC/MS) screening results indicated non-
detectable VOC levels within the 4-ft sleeves from a particular boring, a soil sample for
quantitative GC/MS analysis was selected from the 2-ft section of the sleeve nearest to the
ground water.
• If only one 4-ft sleeve from a boring produced screening level concentrations at detectable
levels, a soil sample was selected for quantitative analysis from the 2-ft section of the sleeve
within the area of highest concentration. An additional soil sample was selected for
quantitative analysis from the 2-ft section of the sleeve nearest ground water whenever the
sample selected by screening was not from the sleeve nearest the ground water level.
• If target compounds were present in multiple 4-ft sleeves within the same boring above
ground water, a soil sample was selected for quantitative analysis from the 2-ft section of the
sleeve shown to be the area of highest concentration. Additional soil samples were selected
for quantitative analysis from the 2-ft section of the sleeve nearest ground water whenever
the sample selected by screening was not from the sleeve nearest the ground water level.
Supplementary samples were selected for quantitative analysis to determine the extent of
contamination from these boring locations.
Field Analytical Technologies [1]
Bruker Thermal Desorption Gas Chromatograph / Mass Spectrometer (TDGC/MS)
The Bruker GC/MS was used with a thermal desorption (TD) sampling probe to perform screening
analyses for VOCs. The technology allows direct volatile vapor sampling analysis of soil samples
without extraction. A sampling probe was held directly over one-inch holes that were cut in the 4-ft
Geoprobe™ sample sleeves, and drew vapors directly into the mass spectrometer. The MS was
operated in the continuous direct measuring mode, simultaneously monitoring eleven targeted
VOCs, with three ions measured for each analyte. The TD sampled the vapor for 30 sec (if screen
was positive) to 1 min (if screen was negative), with the MS readout shown instantly on the
instrument's monitor. An average of 75 soil samples per day were screened over a ten-day period,
for a total of 601 soil samples screened for VOCs.
Tekmar 3000 Purge and Trap Concentrator with Hewlett-Packard 5890 II / 5972 GC/MS
This technology was utilized for quantitative VOC analyses. The Tekmar Purge and Trap system
was used to extract VOCs by mixing the soil sample with reagent water in a sparging vessel and then
purging the sparging vessel with an inert gas. The extracted VOCs were concentrated on a sorbent
trap that was then thermally desorbed to transfer the VOCs to the GC inlet. The Purge and Trap
GC/MS system produced quantitative VOC data for 158 samples over ten days with a 15-min per
sample analysis time. Ion Fingerprint Detection algorithms (see below) were used to expedite the
analysis, increase sensitivity, and reduce the need for reanalysis for dilutions.
11
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Hanscom Air Force Base
• PERFORMANCE EVALUATION ^^^^^^^^^^^^^^^^5
Tufts Thermal Desorption GC/MS
This sample introduction system was utilized for quantitative analyses of PCBs and PAHs. The
thermal desorber sits in-place of the syringe injection GC inlet and was used to introduce a large
volume of sample extract into the GC/MS. Soil samples were extracted with solvent and a portion of
the solvent extract was deposited into a glass sleeve, which was then placed into the TD. The TD
was ballistically heated to 280°C which caused sample analytes to be desorbed and transferred to the
GC column for separation and MS analysis within 15 minutes. The 50-100 (iL injections that are
possible with the thermal desorber maintained the required detection levels even though only two
grams of sample were extracted. Quantitative PCB and PAH data were obtained for 68 soil samples
in 10 minutes per analysis. The Ion Fingerprint Detection (IFD) software (see below) was used to
allow compound identification and quantitation in the reduced run time.
Ion Fingerprint Detection (IFD) Software
The Ion Fingerprint Detection™ data analysis software package was developed at Tufts University
and is commercially available through Ion Signature Technology. It was used on the quantitative
GC/MS systems for the identification and quantitation of analytes. This package provides the
capability of extracting between two and ten characteristic fragment ions produced in mass
spectrometry from targeted organic compounds. Based on a set of mathematical algorithms,
compound identity and concentration are determined. Most MS data analysis software packages can
extract individual ion fragments, however the underlying mathematical algorithms unique to the IFD
software facilitate compound identification for these samples regardless of matrix interferences. IFD
provides the technology necessary to reduce long chromatographic run times from 30-40 minutes to
10 minutes.
Leeman PS-1000 Inductively Coupled Plasma / Optical Emission Spectrometer (ICP/OES)
This technology was used for the quantitative analysis of trace metals contamination in samples.
Soil samples were extracted using a microwave acid digestion and Teflon membrane filtration
procedure. The sample digestion procedure employed a 50 percent 3:2 HNO3:HC1 acid mixture, as
opposed to concentrated HNO3. A comparison study [1] determined that the 50 percent 3:2
HNO3:HC1 acid digestion procedure had benefits such as improved analyte stabilities and recoveries
of certified performance evaluation samples (especially for silver and antimony), while producing
equivalent recoveries and precision for lead determinations in actual field samples. The sample
extracts were then analyzed by ICP/OES in eight-minute analysis times. The ICP/OES in this case
was modified to provide field ruggedness. Movable parts were pneumatically locked in place, the
chassis was ruggedized to stabilize the instrument during field transport, and the nebulizer was
upgraded to a system that can handle samples with high dissolved solids and digestate acid
concentrations. The ICP/OES processed a total of 121 soil samples.
12
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Hanscom Air Force Base
• PERFORMANCE EVALUATION ^^^^^^^^^^^^^^^^5
Sample Collection [1]
There were more samples collected than were projected in the sampling plan, indicating that better
delineation was needed for organic contaminants in and around the three sites. The total number of
projected samples to be screened for VOCs was 585, and 601 samples, or 2.7 percent more, were
actually screened. Higher than projected numbers of samples were quantitatively analyzed for both
VOCs and PCB/PAH, 15.3 and 61.9 percent more, respectively. It is interesting to note that
although no samples were projected to be analyzed for PCB/PAH at Sites 2 and 3, a total of 12 and
10 samples, respectively, were actually analyzed at those sites. There were fewer samples analyzed
for metals than projected. The need for greater than projected numbers of samples for organics
analysis indicated a need for expanded characterization at each of the three sites for VOC and semi-
volatile organic compound (SVOC) contamination.
Sampling Results [1]
Samples were collected from 23 boring locations at Site 1, shown in Figure 3. Quantitative analysis
of 51 samples taken from three borings showed levels of chlorinated VOCs and benzene, toluene,
ethylbenzene, and xylene (BTEX) compounds that equaled or exceeded the 20 DAF action level.
Analyses of samples taken below four feet in depth in only one of those borings showed above
20DAF levels of chlorinated VOCs and BTEX compounds. No metals contamination that exceeded
the 20DAF action level was detected at Site 1. Figure 3 also shows the concentration contours for a
representative chlorinated VOC, cis-l,2-dichloroethene (cis-l,2-DCE).
At Site 2, 58 soil samples were collected from 18 boring locations, shown in Figure 4, for
quantitative analysis. Analyses of samples taken above eight feet in depth from only three of these
showed VOC contamination in excess of the 20DAF action level. Below eight feet in depth,
contamination was found in samples from only two of the three borings that had contained
contamination above eight feet. However, VOC contamination above the action level was found in
three additional borings. Concentrations of metals were below the action level in all borings. Figure
4 displays the concentration contour intervals for a representative BTEX compound, toluene.
At Site 3, samples were collected in 25 boring locations, shown in Figure 5, and 49 samples were
quantitatively analyzed for VOCs. Above action level VOC contamination was detected in three of
the borings at depths less than eight feet, and in only one boring at depths greater than eight feet.
Metals contamination in excess of the action level was found in four of the borings, and Figure 5
shows the cadmium concentration contour plot.
Based on the sampling results obtained at the three sites, volumes of soil contaminated with VOCs
were estimated using site mapping software. For each boring, the screening data were used to
estimate the vertical distance between points of contamination and non-measurable levels. Thus, the
x-z and x-y coordinates were determined by using a combination of quantitative and screening data.
From this, contaminated soil volumes were estimated by linearly interpolating between soil
concentrations above the action level and non measurable levels for each x-z and x-y coordinate.
Approximately 28,000, 243,000, and 66,000 cubic feet of soil are estimated to be contaminated for
Sites 1, 2, and 3, respectively.
13
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Hanscom Air Force Base
I PERFORMANCE EVALUATION
Figure 3: Cis-l,2-DCE Concentrations (in ppb) Above 4 Feet at HAFB Site 1
-i a t f ::--r:^,;| j
:
C6;
'
Q
z
0
T- i
«t
is HI
14
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Hanscom Air Force Base
I PERFORMANCE EVALUATION
Figure 4: Toluene Concentrations (in ppb) Below 8 Feet at HAFB Site 2
•a l '*-
15
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Hanscom Air Force Base
I PERFORMANCE EVALUATION
Figure 5: Cadmium Concentrations (in ppb) At HAFB Site 3
* ' •-
14
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• PERFORMANCE EVALUATION
Method Detection Limit (MDL) Studies [1]
An MDL study was undertaken to verify that VOC concentrations below the action limits could be
detected by the Tekmar Purge and Trap GC/MS. The MDL study was performed at the end of the
field investigation, rather than at the beginning, due to logistical difficulties. An MDL for each
compound was determined by calculating the standard deviation of seven replicate analyses of the
lowest calibration standard (20 ppb), and then multiplying the standard deviation value by 3.14. All
VOC MDLs were found to be below the 10DAF quantitation limit, except for the MDLs of vinyl
chloride and 1,2-dichloroethane. It was agreed that the 1,2-dichloroethane data were sufficient for
confidence of detection at the 20DAF action level, but the vinyl chloride data were unusable.
An MDL study was performed on the Tufts TDGC/MS system for PCB and PAH compounds before
the field investigation and prior to initial calibration. Seven soil samples were fortified with 300 ppb
of PAHs and Aroclor 1248 and analyzed by the TDGC/MS. The MDL was calculated using 3.14
times the product of the relative standard deviation and the concentration injected. The calculated
MDLs for all compounds were well below the 10DAF quantitation limit.
An instrument detection limit (IDL) study was also performed for the field-rugged ICP/OES
technology prior to the field investigation. Although cadmium and lead were the only target metals
for the HAFB project, the IDL study involved 22 metals and metalloids to explore the capabilities of
the instrumentation. MDLs were calculated from the results of the IDL study, and the results
showed that the MDLs for the target metals, cadmium and lead (0.11 mg/kg and 1.65 mg/kg,
respectively), where well below the 10DAF quantitation limits.
VOC Screening Method vs. VOC Quantitative Method [1]
The Bruker TDGC/MS screening results were used to determine if additional sample borings were
necessary and which samples required further analysis. For each sample where the TDGC/MS rapid
screening results indicated the presence of VOCs, quantitative analysis by Tekmar Purge and Trap
GC/MS was performed on those samples to confirm the results. Whereas screening procedures
involved the collection and analysis of sample vapors from over a nickel-sized hole in the sample
borings, quantitative GC/MS data was acquired from the analysis of 5-g soil samples. If no VOCs
were detected by screening throughout an entire sample boring, a sample for quantitative VOC
analysis was taken from the boring sleeve just above the ground water level (as discussed within the
Sample Collection section on page 9). In this way, some samples determined to be negative for
VOCs by the screening method were also analyzed by the quantitative VOC method.
Table 4 presents an evaluation of VOC screening results relative to quantitative results. Of the total
number of soil samples screened for VOCs (601), 144 were quantitatively analyzed. Additionally,
14 soil QC samples were analyzed by both methods. Ninety percent (142/158) of the quantitative
results agreed with the screening results at or above the 10DAF quantitation limit concentration
levels (refer to Table 1). Four percent (6/158) of the samples had screening results which indicated
the presence of VOC compounds at or above the 10DAF levels, but the quantitative method
indicated no detectable VOC concentrations at these levels (false positive screening results). For six
percent of the samples (10/158), the screening TDGC/MS did not detect VOCs at the 10DAF levels,
but VOCs were detected by the Tekmar Purge and Trap GC/MS system at or above the 10DAF
levels (false negative screening results).
15
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• PERFORMANCE EVALUATION
Table 4: Agreement of Screening Results with Quantitative Analysis for VOCs
Level of Interest
Quantitation Limit (10DAF)
Confirmation
90%
False Positive
4%
False Negative
6%
Source: [1]
Instrument Calibration [1]
For quantitative VOC analysis with the Tekmar Purge and Trap GC/MS, the initial calibration
DQOs required that the %RSD of the response factors generated from each of the five calibration
points be less than or equal to 30 percent for two-thirds of the 18 VOC compound results, and less
than or equal to 40 percent for the remaining one-third of the compounds. The DQO requirements
for continuing calibration verification (CCV) performance specified that the percent difference (%D)
between the average response factor from the initial calibration (RFcal) and the continuing
calibration response factor be less than or equal to 30 percent for two-thirds of the compound results,
and less than or equal to 40 percent for the remaining one-third.
The field data generally met the DQO requirements for initial and continuing calibrations for VOC
compounds with the exception of vinyl chloride. This compound exceeded the 40 percent upper
limit for one out of the three initial calibrations and for six out of the 10 CCVs. The problem with
vinyl chloride may have been due to its 100- to 1000-fold greater volatility relative to the other 17
VOC compounds. Not a single detection of vinyl chloride was found for any soil sample at the
achieved detection limit of 33 ppb, but this achieved detection limit was substantially higher than the
10DAF detection limit goal of 5 ppb for vinyl chloride. The data for vinyl chloride were judged
uninformative, but since all data for the other 17 VOC compounds were acceptable and useable for
supporting site decision making, the deficiency of vinyl chloride data was not found to impede this
stage of the site investigation. Table 5 presents the results of initial and continuing calibration tests
for VOCs. Exceedances of the 40 percent DQO criteria were caused by vinyl chloride, with
trichloroethene causing an additional exceedance during a second run of the CCV standard on the
28th.
The DQOs established for initial and continuing calibration for PCB and PAH analyses using the
Tufts TDGC/MS were the same as those for VOCs. The %RSD for the initial calibration must be
less than or equal to 30 percent for two-thirds of the PCB/PAH compound results, and less than or
equal to 40 percent for the remaining one-third of the compounds; and for CCVs, the %D between
the average response factor from the RFcal and the continuing calibration response factor must be
less than or equal to 30 percent for two-thirds of the compound results, and less than or equal to 40
percent for the remaining one-third. Two initial calibrations and six continuing calibration
verifications were performed in the field for PCB and PAH analysis. Initial calibration DQOs were
met for all of the 22 analytes measured. Continuing calibration verification DQOs were not met for
two out of the six CCVs, where some analytes (typically PAHs) fell outside of the 40 percent
difference criteria. This was likely due to a leak that developed in the TD unit which affected
responses for many compounds.
16
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Hanscom Air Force Base
I PERFORMANCE EVALUATION
Table 5: Initial and Continuing Calibration Summary for VOCs
DQO
Goal
%RSD
for 1C1
%D for
CCV2
DQO
Criteria
<30%
<40%
>40%
<30%
<40%
>40%
Date in August 1996
21st
22nd
22nd
23rd
24th
26th
27th
28th
28th
29th
30th
Number of VOC Compounds Meeting Criterion (Percent of Total Meeting Criterion) 3
18
(100%)
0
(0%)
0
(0%)
16
(89%)
2
(11%)
0
(0%)
-
-
-
17
(94%)
0
(0%)
1
(6%)
-
-
-
16
(89%)
1
(6%)
1
(6%)
-
-
-
18
(100%)
0
0
-
-
-
15
(83%)
2
(11%)
1
(6%)
17
(94%)
0
(0%)
1
(6%)
-
-
-
-
-
-
17
(94%)
0
1
(6%)
-
-
-
12
(67%)
5
(28%)
1
(6%)
-
-
-
12
(67%)
4
(22%)
2
(11%)
18
(100%)
0
(0%)
0
(0%)
14
(78%)
4
(22%)
0
-
-
-
13
(72%)
5
(28%)
0
Notes:
1 Percent Relative Standard Deviation for Initial Calibration
2 Percent Difference for Continuing Calibration Verification
3 Total number of VOC compounds was 18
Percentages may not total to 100% due to rounding. A '-' indicates that the test was not performed that day.
Source: [1]
For quantitative metals analysis by ICP/OES, calibration DQOs required that the percent recoveries
of the initial calibration verification (ICV) samples and the CCV samples must fall within 80-120
percent of the reference value for each analyte in the standard solution comprising the calibration
verification samples. The percent recoveries for ICVs and CCVs were well within the specified
DQO for, not only the two target metals (cadmium and lead), but also for the other 20 metal and
metalloid analytes detectable by the ICP/OES.
Method Blanks [1]
The DQO for organic analyses required that blanks be analyzed at the beginning and end of every
day, and after the analysis of highly contaminated samples. The blanks must not contain more than
four target compounds, and their concentrations must be less than three times the quantitation limit.
Method blank criteria for organics were met after methylene chloride was excluded as a target
compound. Despite the use of a fume hood in the field laboratory, blank analyses revealed that high
background levels of methylene chloride from its use as the extraction solvent for the PAH/PCB
analyses performed in the same trailer caused cross-contamination of VOC samples.
The DQO for metals analysis required that ICP/OES instrument blanks and method blanks be
analyzed after every 10th and 20th sample, respectively. The DQO required that corrective action be
17
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• PERFORMANCE EVALUATION ^^^^^^^^^^^^^^^^^^
taken if blank results found analyte concentrations at or above the reporting limit. ICP/OES blanks
consistently met the DQO criteria and no problems were encountered.
Precision [1]
Measurement precision DQOs for quantitative organics analyses using the Tekmar Purge and Trap
with GC/MS on field samples required that duplicates or triplicates be analyzed every 20 samples.
For duplicate samples, the measure of precision was the RPD. For triplicate samples, the
corresponding measure was the relative standard deviation (RSD). If the detected analyte
concentrations were less than five times the quantitation limit (5 x QL), the RPD (for duplicates), or
RSD (for triplicates) must be less then 100 percent. When analyte concentrations were greater than
5 x QL, the RPD or RSD was to be less than 60 percent. The procedure for selecting replicates
resulted in six VOC samples analyzed in duplicate, and two samples analyzed in triplicate. This
precision DQO for analytes detected in these samples was met 78 percent of the time.
Low VOC concentrations (near the MDL and well below the 10DAF QL) in the samples selected as
replicates contributed to the occasional failure to achieve this DQO. No replicate samples had VOC
analyte concentrations greater than 5 x QL. Additionally, workload considerations demanded that
replicates sometimes were not analyzed on the same day as the original sample and a marked decline
in VOC concentrations was apparent with even a single day of sample storage. Although replicate
sample results were not compared to the initial results, but only to back-to-back runs of the replicate
sample, sample storage caused a noticeable deterioration of data quality. VOC replicates run on the
same day as the initial sample had a much greater likelihood of meeting the DQO for replicate
precision.
Measurement precision DQOs could not be evaluated for PCB and PAH analyses because the field
samples selected for replicate analyses had no detectable PCBs or PAHs.
The measurement precision DQOs for metals analysis by field ICP/OES required that replicates be
analyzed every 20th sample, and the resulting RPD or RSD be less than 25 percent. For the target
metal cadmium, only two samples from the nine replicate samples had detectable concentrations of
cadmium. Triplicate RSDs for these two replicates both met the DQO. For lead, the other target
metal analyte, seven of the nine replicates had detectable amounts of lead. Five of those seven
triplicates met the DQO with RSDs of less than 25 percent, and one replicate just "missed" with an
RSD of 27 percent.
Accuracy [1]
Surrogates and Controls
In the HAFB investigation, matrix spikes were not used; however, surrogate recoveries were
evaluated as a measurement accuracy DQO for organic analyses. This DQO required that all
samples for quantitative VOC analysis be fortified with two surrogate compounds, and the recoveries
of the surrogates were to fall between 30-200 percent. Samples for PAH/PCB analysis were fortified
with a single surrogate compound, the recovery of which was to fall within the same range. The
surrogate recovery DQO was met for 82 percent of the quantitative VOC analyses, and 92 percent of
the PAH/PCB analyses.
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• PERFORMANCE EVALUATION ^^^^^^^^^^^^^^^^^^
The accuracy DQOs for metals analysis required that laboratory quality control standards be
analyzed regularly, and the percent recoveries fall within 80-120 percent of the certified value. Two
different controls were used during the field work. An aqueous control standard was analyzed at the
beginning and end of each day to serve as an instrumental control. A solid soil-based standard was
digested and analyzed every 20th sample to serve as a control to evaluate the digestion procedure.
The aqueous control was run a total of 12 times over the work period, and the soil-based control was
run nine times. For the target metal analytes (cadmium and lead), all (100%) of the control
measurements, both aqueous and soil-based, met the DQO. If all 22 analytes for which the ICP/OES
was calibrated are considered, 92 percent of all aqueous and 59 percent of all soil-based control
measurements met the DQO.
Field versus Laboratory Comparison
Another DQO related to measurement accuracy required that comparison between field results and
off-site laboratory results be performed. The sample selection procedure for organics called for the
fifth sample and every tenth subsequent sample to be sent for off-site laboratory analysis, and this
resulted in 14 samples sent for comparison VOC analysis. The accuracy DQO required that the
comparison must agree with less than a 60 percent RPD if the analyte concentrations were greater
than five times the quantitation limit, and with less than a 100 percent RPD if the concentrations
were less than five times the quantitation limit.
Only three of the samples selected in this manner had detectable levels of VOC constituents; the
other 11 samples were non-detect for VOCs by both the on-site and off-site laboratory methods. The
results for the VOC data comparison for these three samples appear in Table 6. These results are
noteworthy for two important reasons: Due to the presence of interferences, Samples S2-B2-(20-22)
and S3-B1-(13-15) required 5:1 and 50:1 dilutions, respectively, before analysis by the off-site
laboratory. For Sample S2-B2-(20-22), this resulted in several compounds being diluted below the
resulting MDL for the off-site laboratory (50 ppb). In contrast, because of the use of the Ion
Fingerprint Detection software's algorithms which are able to "look through" interfering ion signals
without the need for dilution, reportable quantitative results for these VOC compounds were
obtained in the field. Dilution of samples in the field was required only when very high levels of an
analyte exceeded the quantitation range of the MS detector. A reduced need for dilution produced
lower detection limits and more accurate analyte quantitation with the field equipment. Secondly, it
has been well-documented that VOCs are lost in transport and/or storage by the time off-site
laboratories analyze the samples [8, 9]. Field analysis of VOCs may therefore produce results which
are more reliable and more representative of in situ soils. This likely explains the ability of the field
laboratory to detect low levels of VOC constituents in Sample S3-B23-(13-15) whereas the off-site
laboratory did not, and the generally higher concentrations of VOC analytes as reported by the field
laboratory. For these reasons, although the DQO for the comparison between field and off-site lab
results for VOCs was not achieved, this was not considered by any means a reason to lose
confidence in the field-generated data.
The sample selection procedure resulted in five samples being sent for PCB/PAH analysis by an off-
site laboratory. The field versus off-site laboratory accuracy DQO for PCBs and PAHs could not be
evaluated because none of these samples contained these analytes above detection limits.
19
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Hanscom Air Force Base
I PERFORMANCE EVALUATION
Table 6: Field versus Laboratory VOC Data Comparison
Sample ID
S2-B2-(20-22)
S3-B1-(13-15)
S3-B1-(13-15)
S3-B23-(13-15)
Compounds
1 , 1 -dichloroethene
1,1-dichloroethane
cis- 1 ,2-dichloroethene
1,1,1 -trichloroethene
toluene
tetrachloroethane
ethylbenzene
m/p-xylene
o-xylene
toluene
ethvlbenzene
m/p-xylene
o-xylene
1 , 1 -dichloroethene
carbon tetrachloride
tetrachloroethane
ethylbenzene
o-xvlene
Field (ppb)
30
41
560
300
37,000
120
990
7,400
2,200
280,000
3.000
320,000
83,000
15
6
23
7
17
Laboratory (ppb)
<50
<50
<50
250
2,000
<50
240
1,200
480
58,200
14.500
58,700
25,500
<10
<10
<10
<10
<10
The measurement accuracy DQO for target metals in a field versus off-site laboratory comparison
required that the RPD be less than 60 percent, and that the ratio of the field result to the off-site
result be between 0.5 and 2 (i.e., the field result could not be less than half, or more than double, the
off-site result). Eleven samples were submitted to the off-site laboratory for comparison of lead and
cadmium results. Lead results were obtained for all 11 samples, and the DQO was met for 10 of the
11 comparisons. Cadmium results were comparable for only one sample, and for that sample, the
DQO was achieved. Cadmium was frequently detected by the field ICP/OES in the other samples,
but at levels which were below the detection limit of the off-site laboratory.
20
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Hanscom Air Force Base
I COST COMPARISON ^^^^^^^^^^^^^^^^^^^^^^M
Since the investigation at HAFB was conducted as a demonstration under an ETI grant, the actual
costs incurred were not representative of those that would be incurred in a full site investigation. A
cost estimate was prepared, however, to highlight some of the costs that might be incurred in a
comparable site investigation using field analytical technologies and an on-site laboratory. The cost
estimate, shown in Table 7, also provides a comparison between the estimated costs of the dynamic
investigation and those that might be seen using the more traditional approach with off-site
laboratory support. All labor costs associated with collecting samples and obtaining analytical results
are included in this cost estimate.
For both of the traditional scenarios, the number of samples collected and the types of analyses
performed are the same as in the F£AFB investigation. It is assumed that the first traditional scenario
will require two rounds of sampling, each with a separate mobilization. In this scenario, the data
turnaround time is assumed to be two to four weeks. The second traditional scenario is based on
expediting the data turnaround time, and a 50 percent surcharge is assumed to obtain data within two
days. It is also assumed that the sampling and analysis will be conducted in one mobilization and the
field team is held on site until the laboratory results are received. Thus, it is assumed that 21 days
will be needed to complete the investigation (11 days more than the 10 days actually used in the
HAFB investigation).
The analysis shown in Table 7 suggests that a traditional approach to collecting data in a site
investigation might cost between 36 and 57 percent more than the estimated cost of the HAFB
investigation. Clearly, analytical costs make up the largest share of these costs, and the 50 percent
surcharge paid for quick turnaround on the results has a significant impact on the total cost. When
the effect of this surcharge is combined with the cost of holding the field team on site, the cost of
conducting an investigation using the second traditional scenario might be more than double the cost
of the HAFB investigation.
In the analysis provided below, two categories of costs are not addressed, yet such costs may have a
significant impact on the cost of the overall investigation. First, several different technologies may
be used to collect soil samples, other than the Geoprobe that was used at HAFB. Given the
geological setting at HAFB, an example of a likely alternate would be a hollow stem auger. Whether
the cost of collecting samples with an auger is higher or lower than those associated with the
Geoprobe would depend on site-specific factors, such as the local availability of well operators and
the geology of the site. Second, because of the dynamic nature of the HAFB investigation, it is
likely that more effort will be required from mid- to high-level management than would be expected
in a traditional investigation. In the HAFB investigation, the project manager was available every
day to review the previous day's analytical results and make decisions regarding that day's sampling
efforts. Additionally, the EPA remedial project manager spent at least two days of each week at the
site, participating in the decision making process. Such participation is not likely for a traditional
investigation.
21
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Hanscom Air Force Base
COST COMPARISON
Table 7: Cost Comparison between Traditional and Dynamic Field Investigations
Traditional Investigation
Scenario 1
Off-Site Analysis
Data Turnaround
2-4 Weeks
VOC Screening
Analysis
601 Site Samples
60 QC Samples
VOC Quantitative
Analysis
158 Site Samples
16 QC Samples
PCB Quantitative
Analysis
68 Site Samples
7 QC Samples
PAH Quantitative
Analysis
68 Site Samples
7 QC Samples
Metals Quantitative
Analysis
121 Site Samples
12 QC Samples
Analytical Cost
Mobilization Cost
Remob to Collect
Quant Samples
3 Additional Field
Days
Total Project Cost
$39,065
$3,900
$19,750
$2,000
$6,800
$700
$9,860
$1,015
$36,300
$3,600
$122,990
$5,000
$5,000
$6,000
$3,186
$142,176
Traditional Investigation
Scenario 2
Off-Site Analysis
Data Turnaround
2 Days
VOC Screening
Analysis
601 Site Samples
60 QC Samples
VOC Quantitative
Analysis
158 Site Samples
16 QC Samples
PCB Quantitative
Analysis
68 Site Samples
7 QC Samples
PAH Quantitative
Analysis
68 Site Samples
7 QC Samples
Metals Quantitative
Analysis
121 Site Samples
12 QC Samples
Analytical Cost (50%
surcharge)
Mobilization Cost
1 1 Additional Field
Days
Sample Shipping
Total Project Cost
$58,598
$5,850
$29,625
$3,000
$10,200
$1,050
$14,790
$1,523
$54,450
$5,400
$184,486
$5,000
$22,000
$3,186
$214,672
HAFB Investigation
On-Site Analysis
Data Turnaround
Next Day
VOC Screening
Analysis
601 Site Samples
VOC Quantitative
Analysis
158 Site Samples
16 QC Samples
PCB and PAH
Quantitative Analysis
68 Site Samples
7 QC Samples
Metals Quantitative
Analysis
121 Site Samples
12 QC Samples
Analytical Cost
Field Laboratory/
Instrument
Mobilization Cost
Total Project Cost
$19,833
$15,800
$1,600
$6,800
$700
$33,275
$3,300
$81,308
$10,000
$91,308
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Hanscom Air Force Base
OBSERVATIONS AND LESSONS LEARNED ^^^^^^^^^^^5
Summarized below are key findings learned while conducting the HAFB investigation.
Dynamic Workplans and Field Analytical Methods
1. Successful hazardous waste site investigations should be focused with goals and objectives
clearly defined. A dynamic workplan provides an alternative to the traditional approach. It
relies, in part, on an adaptive sampling and analysis strategy. An adaptive sampling and
analysis program requires analytical methods and instrumentation that are field-practical and
can produce data fast enough to support the dynamic workplan process.
2. Successfully implementing dynamic workplans requires that the project manager invest a
significant level of resources at the planning stage and during the field investigation. At
HAFB, the USAF manager was on-site every day, and the EPA remedial project manager
(RPM) was present for at least three days of each week. Furthermore, the technical team
should be in daily communication with the person assigned the responsibility for making all
final field decisions.
3. Field analytical methods can support a dynamic workplan/adaptive sampling and analysis
program by providing near "real-time" information with which site managers can make daily
decisions on sampling locations and analytical requirements.
4. Performance-based field analytical methods are selected and refined to produce data quality
as required to address site-specific project needs. In some cases, field methods can produce
data quality equal to, or surpassing, that generated by fixed (traditional) laboratories
employing standardized EPA methods. The analyses performed during this study generally
met the study DQOs, and were comparable to those used with standard laboratory methods.
5. Cost effectiveness is maximized when site DQOs, analytical throughput rates, data
turnaround times, sample collection rates, and sample analysis costs are evaluated and
optimized to meet the site-specific scientific and engineering questions under investigation
prior to the beginning of the field work. The use of field analytical methods with an
adaptive sampling and analysis plan can result in a higher percentage of the samples
collected and analyzed containing target compounds, which may decrease the number of
uninformative sample results.
6. VOC losses during sample processing may be less when field analytical methods are used to
support a field investigation or cleanup verification program. The longer the sample holding
time and the lower the VOC concentration, the more accentuated the difference between on-
and off-site analytical results.
Field Instrument and Method Performance
1. TDGC/MS and the IFD Software (mass spectrometry data analysis algorithms) allow more
samples to be analyzed per day than current MS vendor data analysis systems, probabilistic
library sample identification matching routines, forward/backward regression search
routines, or compound identification through the standard EPA/NIST library matching data
systems.
23
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OBSERVATIONS AND LESSONS LEARNED
2. The IFD Software can be used to obtain compound selectivity rather than adjusting the gas
chromatography operating conditions. This decreases the per sample analysis time and
increases the number of samples that can be analyzed per day per instrument over standard
GC/MS instruments. The Software algorithms which "look through" non-target MS ion
signals can unambiguously determine compound identity, minimizing masking of low-
concentration target compounds by high-concentration matrix interferents. In this context,
low-level target compounds are not lost because of the need to dilute the sample. Use of the
Software algorithms makes sample dilution less necessary, keeping detection limits low and
saving time and money.
3. TDGC/MS provides increased method detection limits over standard syringe sample
introduction techniques for GC/MS and comparable detection limits with GC with electron
capture detection (BCD) without the need for a sample preconcentration step.
6. TDGC/MS and the IFD Software allow PCB and PAH analyses to be performed in one
analysis without the need for sample cleanup and fractionation time.
7. DQOs were met for all target compounds except vinyl chloride. A trade-off may need to be
considered between achieving low limits of detection for VOC gaseous compounds and
meeting DQOs for all other (less volatile) VOC target compounds.
8. A 50 percent 3:2 HNO3:HCL mixture produced a more stable environment than
concentrated HNO3 for the digestion of all Target Analyte Metals with the exception of
mercury for quantitative ICP/OES analysis.
9. Microwave digestion as a sample preparation method for metals analysis is more practical
for field application than open vessel acid digestion, and recoveries are comparable to what
can be obtained in a fixed laboratory.
Mobile Laboratory Set-up and Operation
1. A minimum of one week is required to install and calibrate all field instruments. MDL
studies should be performed prior to beginning field work.
2. Depending on the number of field instruments, separate electrical services should be
provided per instrument complement.
3. Line voltage regulators are recommended to protect instruments and computers from line
voltage surges or brownouts.
4. Instrument backup or a service repair plan should be incorporated into the workplan as
'contingency planning.' For example, the thermal desorber carrier gas leakage problem was
addressed by using the Tekmar purge and trap system for the HAFB investigation. Later,
the new electrically controlled injection valve system of the thermal desorber was found to
be more rugged than the manual valve unit.
5. Sample pretreatment for SVOC samples should be separated from the VOC sample analysis
area to eliminate sample cross-contamination during the sample extraction process. Good
24
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OBSERVATIONS AND LESSONS LEARNED
ventilation in a field laboratory is critical to prevent sample cross-contamination and
exposure of personnel to hazardous vapors.
6. All instruments can be electronically linked to a data management computer system for ease
of data review and site map generation.
25
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REFERENCES
1 . Robbat, A. A Dynamic Site Investigation Adaptive Sampling and Analysis Program for
Operable Unit 1 atHanscom Air Force Base Bedford, Massachusetts. Tufts University,
Center for Field Analytical Studies and Technology, Medford (MA). Approved December
1997.
2. Robbat A. A Guideline for Dynamic Workplans and Field Analytics: The Keys to Cost-
Effective Site Characterization and Cleanup. Tufts University, Center for Field Analytical
Studies and Technology, Medford (MA). Approved December 1997.
3. Personal Communications with Robert Lim, EPA RPM. May 20, 1998.
4. Personal Communications with Thomas Best, USAF. May 27, 1998.
5. U.S. Environmental Protection Agency. Soil Screening Guidance: Technical Background
Document. Office of Solid Waste and Emergency Response, Washington, DC. EPA/540/R-
96/128. NTIS PB 9355,4-23. April 1996.
6. U.S. Environmental Protection Agency. Revised Interim Soil Lead Guidance for CERCLA
Sites andRCRA Corrective Action Facilities. EPA/540/F-94/043.
7. U.S. Environmental Protection Agency. The Rapid Optical Screening Tool (ROST™) Laser-
Induced Fluorescence (LIF) System for Screening of Petroleum Hydrocarbons in Subsurface
Soils. Office of Research and Development, Washington, DC. EPA/600/R-97/020. February
1997.
8. Minnich, MM., BA Schumacher, JH Zimmerman. Comparison of soil VOCs measured by
soil gas, heated headspace, and methanol extraction techniques. Journal of Soil
Contamination 6 (2): 187-203 (1997).
9. Hewitt, A.D. Comparison of collection and handling practices for soils to be analyzed for
volatile organic compounds. In: Volatile Organic Compounds in the Environment. (Wang,
W., Schnoor, J., and Doi, J., Eds.) ASTM STP 1261, pp. 170-180. American Society for
Testing and Materials, West Conshohoken, PA. (1994).
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