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TRANSCRIPT
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Passive Soil Gas Sampling: A Cost Effective Approach to Identify Source Areas
and Vapor Intrusion Pathways, Delineate Contaminant Plumes, and Optimize
Remediation Systems
By: Harry O’Neill
Beacon Environmental Services, Inc.
May 3, 2012
Presented to: U.S. EPA Technical Support Project
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Road Map
• Passive Soil Gas (PSG): Background and Technology
• Why PSG Surveys: Spatial and Temporal Variability of VOCs/SVOCs in
the Subsurface
• QA/QC Procedures: In the Field and In the Lab
• How to use PSG Data
• Case Study: Application and Results Targeting Source Area and
Delineating PCE Plume
• Conclusions
• Resources -- New Guidance Documents Available
3
Experience -- The Company
• Beacon Environmental formed in 1999 with the focus of providing site characterization solutions through the use of advanced passive soil gas (PSG) sampling methodologies.
• Beacon provides PSG services throughout the United States, as well as internationally, and continues to improve upon the process and understanding of subsurface vapor movement.
• Beacon supports the research community by aligning ourselves with several prominent universities to further the understanding of soil vapor dynamics and develop innovative sorbent based sampling and analytical methods for soil gas, indoor air, and ambient air applications.
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Experience -- The People
• Beacon’s staff has managed soil gas investigations for more than 20 years working on both industrial and military projects.
• We have been on the forefront of the acceptance of passive soil gas sampling technologies at both the national and international level and have overseen the implementation of over one-thousand soil gas surveys.
• Harry O’Neill is the lead author of the recently drafted ASTM Standard: D7758-11, Standard Practice for Passive Soil Gas Sampling in the Vadose Zone for Source Identification, Spatial Variability Assessment, Monitoring, and Vapor Intrusion Evaluations.
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BESURE Sample Collection Kit
Passive Soil Gas Technologies are typically provided through easy to use sample collection kits.
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Easy-to-Use in the Field
PSG Technologies are easy to use and are designed to maintain high quality control (QC) in the field
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ASTM D5314 and D7758 Compliant Sampler
The sorbents need to be hydrophobic and the housing of the PSG Samplers should not contain sorptive materials (e.g.,
PDMS or other membranes) that will compete with the sorbents and bias results
Two types of adsorbents to target a broad
range of compounds
Two pairs for duplicate or confirmatory
analysis
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Applications
• Identify source areas and release locations of VOCs/SVOCs
• Focus soil and groundwater sampling locations
• Focus remediation plans
• Identify vapor intrusion pathways
• Track groundwater plumes
• Monitor remediation progress
• TRIAD Approach – Expedited Site Characterization
PSG surveys are routinely performed to:
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Routine Targets
Halogenated compounds • PCE • TCE • DCEs • Vinyl chloride • TCA • Carbon tetrachloride • Chloroform • Freons • Chlorobenzene • Dichlorobenzenes • Trichlorobenzenes
Complex mixtures • Stoddard solvent • Paint thinners Petroleum Blends • Gasoline • Fuel oil • Diesel • Jet Fuel BTEX, MTBE and PAHs • Naphthalene • 2-Methylnaphthalene
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Additional Targets
Heavier PAHs • Acenaphthalene, Fluorene, Pyrene
Ketones
Alcohols
Explosives
Pesticides
Chemical Warfare Agent (CWA) and Breakdown Products
• Mustard, GB, VX, 1,4-Thioxane, 1,4-Dithiane, Thiodiglycol
Mercury (Hg)
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• Maximize the number of locations that can be sampled
• Reduce uncertainty, surprises, and unforeseen costs
• Make well-informed and appropriate corrective action decisions
• Rapidly collect accurate data
Why PSG Surveys? – Spatial Variability
Benefits of PSG Surveys:
Overcome the challenges of SPATIAL VARIABILITY of subsurface contamination by allowing you to collect a high resolution data set
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Why PSG Surveys? – Temporal Variability
Overcome the challenges of the TEMPORAL VARIABILITY of soil gas concentrations by collecting time-integrated measurements over several days or weeks
Soil gas concentrations can change daily and
even hourly at the same location.
On which day and at what time should you collect an
active soil gas sample? Chart courtesy of
Ion Science
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Why PSG Surveys? – Cost Saving Approach
"If we had not had the soil gas data we would have taken 200 borings (identified by ground penetrating radar) across the entire site. Instead we were able to drill only about 40 borings, which resulted in excellent data.” – Bhate Environmental
High Density, Low Cost Low Density, High Cost
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Why PSG Surveys? – Versatile Technology
Passive Targets a Broader Range of VOCs and SVOCs than Active
Effective in Most Soil and Geologic Conditions
Time Integrated… able to identify contamination at low concentrations
“The Circles of Trust”
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Sustainable Technology
IN THE FIELD No waste from soil cuttings are generated when sampling.
Only hand tools required to collect samples -- no DPT or drill rigs. In-situ sample collection onto adsorbents that are reused, no waste.
IN THE LAB Samples analyzed using thermal desorption-gas chromatography/
mass spectrometry (TD-GC/MS) instrumentation. No solvents are used for sample extraction.
Green CharacterizationTM
A green site investigation relies on information gained from a thorough preliminary assessment that identifies target areas and
site conditions through minimally intrusive techniques. -- USEPA OSWER Dec. 2009
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Precision In Sampler Design
Each PSG Sampler is made of inert materials in accordance w ith ASTM protocols – no membranes are used which can act as competing adsorbents
Each PSG Sampler contains an equal mass of hydrophobic
adsorbents weighed out w ith an analytical balance
Important for consistency of sampling from one location to another and allows for excellent reproducibility and precision,
as demonstrated w ith duplicate field samples
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Precision In The Lab
• Analysis by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) following EPA Method 8260C or equivalent
• Analytical results based on 5-point initial calibration
• Internal standards and surrogates included with each analysis
• Daily continuing calibration checks
• Duplicate field samples
• System daily tunes
• Method blanks
• Method Detection Limit (MDL) Studies
• Meets requirements of EPA Level III/Level IV data quality objectives
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Survey Reports
Reports are provided with a narrative discussing QA/QC findings and include tabular results, as well as color isopleth maps showing distribution of compounds.
Options:
EDDs (e.g., SEDD 2A)
EPA CLP Summary Forms
Surrogate Results
TICS
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Reported Data in Units of Mass… Not Concentration
PSG data should not be reported in units of concentration No agencies or regulators accepting PSG data converted to concentration All soil gas guidance documents clearly state data not to be used for determining concentration However, reporting data in units of mass (ng or ug) meets project objectives to characterize sites and guide where to collect a limited number of soil, gw, or active soil gas samples
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Temporal Variability
Separate objective is to determine the average or worst case soil gas concentrations
Soil gas concentrations can change daily and
even hourly at the same location.
On which day and at what time should you collect an
active soil gas sample? Chart courtesy of
Ion Science
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Applications
EXAMPLE PROJECTS
A04
A05
A06
A07
A08
A09
B04B05
B06
B07
B08 B09
C04C05
C06
C07
C08C09
D04D05
D06
D08
D09
E04E05
E06
E07
E08E09
F04
F05
F06
F07
F08
F09
G04
G05
G06
G07
G08G09
G10
G12
G14
G16
H04H05
H06H07
H08
H09
H10
I04I05
I06
I07
I08
I09
I10
I12
I14
I16
J04
J05
J06
J07
J08J09
J10
K04
K05
K06K07
K08K09
K10
K11
K12
K13
K14
K15
K16
K17
K20
L04
L05
L06
L07
L08L09
L10
L11
L12
L13
L14
L15
L16
L17
M04
M05
M06
M07
M08M09
M10
M11
M12
M13
M14M15
M16
M17M18
M20
M22
N04
N05
N06N07
N08
N09
N10
N11
N12
N13
N14
N15
N16
N17
N18
O04O05
O06O07
O08O09
O10O11
O12
O18
O20O21
O22
P04
P05
P06P07
P08P09
P10
P11
P12P13
P14
P15
P16
P17
P18
P20
P21
P22
Q04
Q05Q06
Q07
Q09
Q10
Q11Q12
Q13
Q14
Q15
Q16
Q17
Q18
Q20Q21
Q22
Q30Q32
R01
R02
R03
R04
R05
R06
R07
R08R09
R10
S01
S02S03
S04S05
S06
S07
S08
S09
S10
S12
S22
T01
T02
T03T04
T05
T06
T07
T08
T09
U01
U02 U03
U04U05
U06 U07
U08
U09
U10
U12
U14
U16
U18
U20
U22
V01
V03
V04
V05
V06
V07
V08
W01
W02
W03
W04
W05W06
W07
W08
W10
Y08
D07
O17
T10
V02Scale in Feet
2601300
Q08
Q31
12,203
Color Scale(nanograms)
0
25,000
50,000
75,000
100,000
125,000
150,000
175,000
200,000
225,000
250,000
275,000
300,000
325,000
22-122-222-3
23-123-223-323-423-523-623-723-8
55-1
55-2
55-3
55-4
55-5
A-1A-2A-3A-4A-5A-6A-7A-8A-9A-10A-11
B-1B-2B-3B-4B-5
C-1
C-2
IP-1
IP-2
IP-3
IP-4
IP-5
IP-6
IP-7
IP-8
IP-9
IP-10
P-1
P-2
P-3
P-4
P-5
P-6
P-7
P-8
P-9
P-10
14 J15 J4316 J12 J5 J31
12 J
6 J
145
67
6 J
7 J
8 J
28
13 J
12 J
9 J
ALAMEDA DRIVE ALAMEDA DRIVE
IND
UST
. PA
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AVE
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PRIE
ST D
RIV
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IEST
DR
IVE
PRIE
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55TH
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23RD ST.
21ST ST.
CU
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BROADWAY ROAD
Color Scale(nanograms)
0
25
50
75
100
125
150
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Example Project: Manufacturing Site Investigation
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Example Project: Gas Station Investigation
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Example Project: DOD Site – Identify Fuel Releases
A04
A05
A06
A07
A08
A09
B04B05
B06
B07
B08 B09
C04C05
C06
C07
C08C09
D04D05
D06
D08
D09
E04E05
E06
E07
E08E09
F04
F05
F06
F07
F08
F09
G04
G05
G06
G07
G08G09
G10
G12
G14
G16
H04H05
H06H07
H08
H09
H10
I04I05
I06
I07
I08
I09
I10
I12
I14
I16
J04
J05
J06
J07
J08J09
J10
K04
K05
K06K07
K08K09
K10
K11
K12
K13
K14
K15
K16
K17
K20
L04
L05
L06
L07
L08L09
L10
L11
L12
L13
L14
L15
L16
L17
M04
M05
M06
M07
M08M09
M10
M11
M12
M13
M14M15
M16
M17M18
M20
M22
N04
N05
N06N07
N08
N09
N10
N11
N12
N13
N14
N15
N16
N17
N18
O04O05
O06O07
O08O09
O10O11
O12
O18
O20O21
O22
P04
P05
P06P07
P08P09
P10
P11
P12P13
P14
P15
P16
P17
P18
P20
P21
P22
Q04
Q05Q06
Q07
Q09
Q10
Q11Q12
Q13
Q14
Q15
Q16
Q17
Q18
Q20Q21
Q22
Q30Q32
R01
R02
R03
R04
R05
R06
R07
R08R09
R10
S01
S02S03
S04S05
S06
S07
S08
S09
S10
S12
S22
T01
T02
T03T04
T05
T06
T07
T08
T09
U01
U02 U03
U04U05
U06 U07
U08
U09
U10
U12
U14
U16
U18
U20
U22
V01
V03
V04
V05
V06
V07
V08
W01
W02
W03
W04
W05W06
W07
W08
W10
Y08
D07
O17
T10
V02Scale in Feet
2601300
Q08
Q31
12,203
Color Scale(nanograms)
0
25,000
50,000
75,000
100,000
125,000
150,000
175,000
200,000
225,000
250,000
275,000
300,000
325,000
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Example Project: DOE Site – Identify Legacy CCl4
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Example Project: TCE Source Area and Plume
22-122-222-3
23-123-223-323-423-523-623-723-8
55-1
55-2
55-3
55-4
55-5
A-1A-2A-3A-4A-5A-6A-7A-8A-9A-10A-11
B-1B-2B-3B-4B-5
C-1
C-2
IP-1
IP-2
IP-3
IP-4
IP-5
IP-6
IP-7
IP-8
IP-9
IP-10
P-1
P-2
P-3
P-4
P-5
P-6
P-7
P-8
P-9
P-10
14 J15 J4316 J12 J5 J31
12 J
6 J
145
67
6 J
7 J
8 J
28
13 J
12 J
9 J
ALAMEDA DRIVE ALAMEDA DRIVE
IND
UST
. PA
RK
AV E
.
PRIE
ST D
RIV
EPR
IEST
DR
I VE
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ST D
RIV
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55TH
ST R
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23RD ST.
21ST ST.
CU
TLER
DR
.
BROADWAY ROAD
Color Scale(nanograms)
0
25
50
75
100
125
150
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Case Study: Identify Source Area and Track Plume
Objective: Identify Source of PCE in Monitoring Well
PCE concentration in groundwater is 6.8 ug/L
Challenges: Urban Environment Multiple potential source areas present Gaining access to properties difficult PCE concentration at low ppb level in gw at 5 m depth
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OVERALL GRID PATTERN 74 PSG Samplers
Sampled near PRPs and in public right of ways.
Groundwater was approximately 5 meters bgs
10 m spacing near two dry cleaners
Typically 30 m spacing along public right of ways
Case Study – PSG Sampling Plan
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Case Study – PSG Sampling Plan
GRID NEAR DRY CLEANERS
Locations of former and active
dry cleaners
Location of MW-1 which reported 6.8 ppb of PCE
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Definitively identified PCE releases from
former and active dry cleaners.
Non-Detects Excluded out other PRPs
Tracked plume to downgradient well contaminated with
PCE by sampling in public right of ways.
Case Study – Results
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Case Study – GW Results
PSG Data and GW data correlated very well
GW data isoconcentration maps confirming PSG findings
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Case Study – Findings
Findings: • PSG data for PCE ranged from non detects to 29,117 ng
• Sources of PCE releases were identified
• PCE measurement of 29,117 ng equated to 17,000 ug/L in gw
• PSG data identified migration pathways from source areas to impacted monitoring well – plumes commingled
• PCE measurement of 125 ng equated to 6.8 ug/L in gw – SENSITIVE METHOD
Client Stated: “The PSG survey proved to be a cost-effective method to identify the source areas and the extent of the PCE plume. A minimal number of soil borings to collect grab groundwater samples was required to confirm the results of the passive soil vapor survey, thus minimizing costs.”
Reference: Clarke, Goodwin, O’Neill, Odencrantz, Preliminary Investigation of a Perchloroethylene (PCE) Groundwater P lume using a Passive Soil Gas Survey, 2008, REMEDIATION, Wiley Periodicals, Vol. 18, No. 4.
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Conclusions
• PSG Surveys Reduce Data Gaps and Overcome the Uncertainty Associated With Subsurface Spatial Variability
• PSG Surveys Collect Time-Integrated Samples over Several Days or Weeks and Overcome the Uncertainty Associated with Temporal Variability
• PSG Surveys Can Rapidly Characterize a Site for a Broad Range of Compounds (VOCs and SVOCs) with Minimal Disturbance to the Site
• Advanced PSG Surveys will Identify Source Areas, as well as Delineate the Contaminant Plume even at Low Concentrations
• When Strict QA/QC Procedures are Followed in the Field and in the Lab, the Resulting PSG Data will Best Reflect Subsurface Concentrations
• High-Quality PSG Data Sets Minimize the Required Number of Soil and/or Groundwater Samples
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ASTM D7758-11 – Approved Dec. 1, 2011
Standard Practice for Passive Soil Gas Sampling in the Vadose Zone for Source Identification, Spatial Variability Assessment, Monitoring, and Vapor Intrusion Evaluations.
Provides guidance on: • Sampler design • Sampling depth • Sampler exposure periods • Sampling procedures • Applications • Limitations • Field QC samples • Reporting • Data Usage
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Additional Resources
Brownfields Technology Primer: Vapor Intrusion Considerations for Redevelopment U.S. EPA Office of Solid Waste and Emergency Response, EPA Document No. 542-R-08-001, 2008.
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Additional Resources
Cal/EPA DTSC -- Guidance For The Evaluation And Mitigation Of Subsurface Vapor Intrusion To Indoor Air (Vapor Intrusion Guidance), October 2011 US EPA OSWER Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance) – Final Scheduled for Nov. 2012 Byrnes, M.E., Field Sampling Methods for Remedial Investigations, CRC Press, New York, 2009. New Jersey Department of Environmental Protection Field Sampling Procedures Manual, 2005.
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Any Questions?
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Thank You!
Please contact us if you have any questions:
Beacon Environmental Services, Inc. Harry O’Neill
President Bel Air, MD 21014 USA
1-410-838-8780 www.beacon-usa.com