U S EPA P t l H d b VU.S. EPA Petroleum Hydrocarbon...
Transcript of U S EPA P t l H d b VU.S. EPA Petroleum Hydrocarbon...
U S EPA P t l H d b VU.S. EPA Petroleum Hydrocarbon Vapor Intrusion (PHC-VI) Database – A
C h i A l i f A tiComprehensive Analysis of Aromatic and Aliphatic Hydrocarbon Data
Ian Hers, Golder AssociatesR b t T d l RTI I t ti lRobert Truesdale, RTI International
22nd Annual International Conference onSoil, Water, Energy, and Air
San Diego, March 19-22, 2012
PRESENTATION OUTLINE
Acknowledgment: Great work by Robin Davis (in part the source of this database) and complementary efforts by Matt Lahvis and Jackie Wright (& input by many others)
Motivation and project objectivesD t b t t d t t
Lahvis and Jackie Wright (& input by many others)
Database structure and contentScreening indicators for dissolved versus LNAPL source sitessource sitesDatabase analysis methodsDatabase analysis results and recommended exclusion distancesInclusionary criteria
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MOTIVATION AND OBJECTIVES
AF ? Approaches for assessment of PHC-VI that do not account for aerobic biodegradation are overly conservative Through (i) empirical data analysis and (ii) modeling studies develop better(ii) modeling studies develop better understanding of conditions for vapor attenuation and conversely potential f l t PVI thfor complete PVI pathwayDevelop better screening approaches based on exclusion distances
GOLDER ASSOCIATES
based on exclusion distances (together with inclusionary criteria)Focus Subtitle I UST sites
MOTIVATION AND OBJECTIVES
Approaches for assessment of PHC-VI that do not account for aerobic biodegradation are overly conservative Through (i) empirical data analysis and (ii) modeling studies develop better(ii) modeling studies develop better understanding of conditions for vapor attenuation and conversely potential f l t PVI thfor complete PVI pathwayDevelop better screening approaches based on exclusion distancesBio zone
GOLDER ASSOCIATES
based on exclusion distances (together with inclusionary criteria)Focus Subtitle I UST sites
CONCEPTUAL SITE MODEL
Aerobic biodegradation of petroleum hydrocarbon vapors is
a) LNAPL SOURCE
UNSATURATED ZONE sharp reaction front
O2
VOChigh mass
fluxpetroleum hydrocarbon vapors is robust and relatively rapid process
CAPILLARY ZONE
SATURATED ZONE
VOCsflux
constituent distributions
Key is sufficient oxygen supply relative to oxygen demand , which is a function of PHC flux
b) DISSOLVED-PHASE SOURCE
Owhich is a function of PHC fluxSignificant difference in source vapor concentrations and flux for CAPILLARY ZONE
UNSATURATED ZONE
limited mass flux sharp
reaction f t
O2
VOCs
dissolved vs. LNAPL sourcesSATURATED ZONE
front
constituent distributions
Lahvis et al. (2012)
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( )
CONCEPTUAL SITE MODEL
Conceptual site factors that could result in increased potential for PHC-VI:potential for PHC VI:
Shallow LNAPL, large releasesPreferential pathways – direct connectionsLarge buildings and capping effect – modeling studies suggest only potentially significant at LNAPL sites, will also depend on O transport through concrete whichalso depend on O2 transport through concrete, which can be significantMethane generated from gasoline containing ethanol –g g gpotential significance not well understand, research in progress to address this
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INCLUSIONARY CASE STUDIES
Sites with likely or confirmed complete PHC-VI pathway and oxygen < 1 % in subslab vapor
Site DistanceLNAPL-Building
Building Size
Source TPHVapor Conc.
(mg/L)
Faciilty Comment
C (L t 1 5 ft 2 300 ft2 100 R fi Sh llCasper (Luo et al., 2007)
1-5 ft 2,300 ft2 ~ 100 Refinery Shallow source
Chatterton (Hers t l 2000)
5 ft 610 ft2 ~ 40 Petro-h i l
Only when ΔP10 Pet al., 2000) chemical ~ 10 Pa
Perth (Patterson & Davis, 2009)
10 ft 2,700 ft2 ~ 20 Refinery 30 ft. buildingapron 3 sides
Unknown (Luo et al., 2010)
25-30 ft 2,100 ft2 ~ 60-160 Refinery Capping effect from geology
All large volume releases
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71 mg/L = 106 μg/m3
g
DATABASE PROCESS & SITES
Robin’s database starting point (great body of work!)ACCESS and EXCEL databases created, with references
Minnesota 22Utah 15
Added data for new sites (primarily Maine) and for existing sites (new fields)Checked data, screened
Maine 12 California 7Ohio 4N J 3
Checked data, screened data based on quality indicators, added filters – process to ensure MN
CA New Jersey 3Maryland 1South Carolina 1US unknown 1
process to ensure completeness and “data of known quality” Most gasoline sites (data UTME
CA
Canada 3Most gasoline sites (data obtained 1995-2011)38 sites with buildings
UTME
70 Sites
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DATABASE FIELDS
Background data: Site location, generic soil description, contamination type, etc.Facility type: UST, terminal, refinery, petrochemical.Site conditions: Soil type, porosity, moisture, surface cover at soil gas probe (ground pavement building)cover at soil gas probe (ground, pavement, building), depth to water table, depth to contamination, etc.Soil gas probe data: Depth, construction, & lateral distances: well, UST facility infrastructure, building.Analytical data: Date, analytical method, QC data, soil chemistry groundwater chemistry soil vapor chemistrychemistry, groundwater chemistry, soil vapor chemistry.Building data: Building use (e.g., residential, commercial, institutional), foundation type, building size, etc.
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) y g
DATA SCREENED OUT BASED ON QC INDICATORS
Analytical data obtained by unacceptable methods [Acceptable PHC methods: EPA Method TO-15, EPA Method TO-3, Modified EPA 8260/8015 and Massachusetts Air Phase Hydrocarbons (APH), Acceptable fixed gas methods: ASTM D1946 and EPAAcceptable fixed gas methods: ASTM D1946 and EPA Method 3C]Soil gas data from fractured rock systemsBenzene concentrations in groundwater below detection levelLateral spacing between groundwater monitoring well andLateral spacing between groundwater monitoring well and soil gas probe (for paired data) > ~ 30 ft (information not available for all data).
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NUMBER SOIL VAPOR ANALYTES
Benzene 879Toluene 362BCH4
879
362594
357Ethylbenzene 362Xylenes 377Naphthalene 266224 Trimethylpentane 43
B
T
CO2
362
36237787
645224‐Trimethylpentane 43Hexane 147Heptane 143MTBE 121
EO2
3772364314714312187
772 1,3‐Butadiene 87TPH 772MADEP TPH FractionsOxygen 645
XNTPH
Oxygen 645Carbon Dioxide 594
823 paired benzene groundwater-soil vapor records
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p g p
DATA ANALYSIS OVERVIEW
Soil gas proximate to LNAPLor dissolved source?
Database contains data from following facilities:
1 Exploratory Data Analysis
g1. UST2. Refinery3 Terminal1. Exploratory Data Analysis 3. Terminal4. Petro-chemical
A l i d t d f2. Vertical Distance Method Analysis conducted for:1. Dissolved (all facilities
but mostly UST)
3. Clean Soil Thickness (Davis) Method
y )2. LNAPL (UST only)3. LNAPL (all facilities)
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LNAPL PHC INDICATORSType Indicator Measures & Screening Values
Adopted for this study Direct LNAPL presence [controlling
indicator ~ 80% of time]LNAPL in wells, sheens in soil, shake and dye test resultsindicator ~ 80% of time] shake and dye test results
Indirect Concentrations approaching (>0.2) effective solubilities or “Csat” concentration [controlling indicator ~ 15% of
Groundwater - benzene > 5 mg/L - TPH > 30 mg/L (gasoline) Soil[controlling indicator 15% of
time] Soil - benzene > 10 mg/kg - TPH > 250 mg/kg (gasoline)
Indirect Proximity to source area likely to be impacted with LNAPL
Soil gas probes < 20 ft UST infrastructureto be impacted with LNAPL
[controlling indicator ~ 5% time] infrastructure
Other potential indicators Indirect Fluorescence response in
LNAPLUV, LIF, or UVIF fluorescence
LNAPL rangeIndirect Organic vapor analyzer (e.g.,
photoionization detector) >500 ppmV
Indirect Petroleum hydrocarbon vapor, PHC vapor & CO2 concentrations
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Indirect Elevated aliphatic soil gas concentrations
Hexane > 100,000 ug/m3 (Lahvis et al, 2012)
DEPTH TO TOP OF CONTAMINATION
NAPLSoil gas probes
Top of LNAPL smear/soil contamination zone estimated from logs, PID results, historical maximum water table height
DISSOLVEDWater table measured approximately same time as soil gas
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VERTICAL DISTANCE METHOD
Compare soil vapor concentrations to risk-based vapor concentrations for varying source-building distancesFor benzene, estimate probabilities for vertical source-separation distances bins: ≥ 0, ≥ 2,.., ≥ N, for dissolved & LNAPL sources:LNAPL sources:
P [Cv <=Cthreshold /z > d; NAPL or dissolved]
P = N [C < C ] / N [TOTAL]P = N [CV < CTHRESHOLD] / N [TOTAL]
Non-detects addressed through ½ DL replacement method and Kaplan-Meier methodand Kaplan Meier methodProbability > 95% less than threshold suggested as a basis for exclusion distance
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CLEAN SOIL THICKNESS (DAVIS) METHOD
Vertical thickness of clean soil required for benzene vapors to attenuate below 100 ug/m3vapors to attenuate below 100 ug/mMethod 1
Distance from top of contamination to first soil gas probe where benzene vapor < 100 ug/m3
Method 2 InterpolationDi t f t f t i ti t i t l t dDistance from top of contamination to interpolated distance between probes with benzene vapor > 100 and < 100 ug/m3
Both methods subject to maximum vertical probe spacing (10 ft) constraint to ensure adequate resolution
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RISK SOIL VAPOR CONCENTRATIONS
General approach for estimating risk-based vapor concentration (Cthreshold)
Cthreshold = Cair/AF
Where Cair = risk-based air concentration (from EPA IRIS database for lifetime exposure and no amortization)AF = 0 01 (based on modeling studies & EPA (2012)AF = 0.01 (based on modeling studies & EPA (2012) database for subslab AF where 50th and 95th percentiles of the subslab attenuation factor = 0.0025 and 0.02)For benzene, thresholds (50 and 100 ug/m3) adjusted based on practical considerations [within 10-5 and 10-6 cancer risk level ]
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cancer risk level ]
GROUNDWATER FOR DISSOLVED AND LNAPL SOURCES
100000/L)
Benzene Groundwater Concentrations
NAPL (all) N=198
1000
10000
Conc. (ug
/
Dissolved N = 98
100
1000
ound
water
10
Benzen
e Gro
10% 20% 40% 60% 80% 100%
B
Cumulative Frequency
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q y
GROUNDWATER vs. DEEP VAPOR
Benzene ‐ GW vs SV ‐ Dissolved (N=45)
DISSOLVED LNAPL (all)Benzene ‐ GW vs SV ‐ NAPL (all) (N=127)
1.E+05
1.E+06
1.E+07
m3)
( )
1.E+05
1.E+06
1.E+07
/m3)
Benzene GW vs SV NAPL (all) (N 127)
Henry's Law prediction, CVH
Henry’s Law prediction
1.E+02
1.E+03
1.E+04
or C
onc. (ug
/
CvH/ 10
1.E+02
1.E+03
1.E+04
or Conc. (ug/prediction
1.E‐01
1.E+00
1.E+01
Soil Vapo
1 E 01
1.E+00
1.E+01
Soil Vapo
1 m
g/L
1.E 011 10 100 1000 10000 100000
Groundwater Conc. (ug/L)
1.E‐011 100 10000
Groundwater Conc. (ug/L)
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VERTICAL DISTANCE METHOD - DISSOLVED
33 sites233 data points
1.E+04
1.E+05
1.E+06
/m3)
Benzene vs. Distance ‐ Dissolved
> DL
< DL
949698
100
Threh
old
Benzene Conditional Probability ‐Dissolved
1.E+01
1.E+02
1.E+03
Vapo
r Con
c. (ug
100 ug/m3
50 ug/m38688909294
ty Vapor Con
c. <
Probability < 100 (1/2DL)Probability < 50 (1/2DL)
1.E‐01
1.E+00
‐10 0 10 20 30 40
Benzen
e
Distance soil vapor probe & contamination (ft.)
808284
0 1 2 3 4 5
Prob
aili
Distance soil vapor probe & contamination (ft.)
y ( / )Probability < 100 (KM)Probability < 50 (KM)
20
25
(%)
Oxygen vs. Distance ‐ Dissolved
1.E+04
1.E+05
1.E+06
. (ug
/m3)
Xylenes vs. Distance ‐ Dissolved
> DL< DLRBCv
5
10
15
Oxygen Co
nc. (
1.E+01
1.E+02
1.E+03
enes Vapor Con
c.
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200
5
‐10 0 10 20 30 40Distance soil vapor probe & contamination (ft.)
1.E‐01
1.E+00
‐10 0 10 20 30 40
Xyle
Distance soil vapor probe and contamination (ft.)
VERTICAL DISTANCE METHOD - DISSOLVED
1.E+04
1.E+05
c. (u
g/m3)
C9‐12 Aliphatic vs. Distance ‐ Dissolved
> DL
RBCv
1.E+05
1.E+06
1.E+07
(ug/m3)
C5‐C8 Aliphatic vs. Distance ‐ Dissolved
> DL
< DL
RBC
1 E 01
1.E+02
1.E+03
phatic Vapor Con
c > DL
< DL
1.E+02
1.E+03
1.E+04
hatic Vapo
r Co
nc. RBCv
1.E+00
1.E+01
‐10 10 30 50
C9‐12 Alip
Distance soil vapor probe and contamination (ft.)
1.E+00
1.E+01
‐10 10 30 50C5‐C8 Aliph
Distance soil vapor probe and contamination (ft.)
1.E+04
1.E+05
c. (ug
/m3)
C9‐C10 Aromatic vs. Distance ‐ Dissolved
> DL
< DL 1.E+04
1.E+05
. (ug
/m3)
Hexane vs. Distance ‐ Dissolved
> DL
< DL
RBCv
RBCv
1 E+01
1.E+02
1.E+03
phatic Vapor Con
c
1 E+01
1.E+02
1.E+03
ane Vapor Con
c
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211.E+00
1.E+01
‐10 10 30 50C9‐C10
Alip
Distance soil vapor probe and contamination (ft.)
1.E+00
1.E+01
‐10 0 10 20 30
Hexa
Distance soil vapor probe and contamination (ft.)
VERTICAL DISTANCE METHOD – NAPL (UST sites)
39 sites330 data points
1.E+05
1.E+06
1.E+07
(ug/m3)
Benzene vs. Distance ‐NAPL (UST only)
> DL
< DL
80
100
120
Threshold
Benzene Conditional Probability ‐NAPL (UST only)
1.E+01
1.E+02
1.E+03
1.E+04
ene Vapo
r Con
c.
40
60
80
y Vapo
r Con
c. < T
Probability < 100 (1/2DL)Probability < 50 (1/2DL)
100 ug/m3
50 ug/m3
1.E‐01
1.E+00
‐10 10 30 50
Ben
ze
Distance soil vapor probe and contamination (ft.)
0
20
0 5 10 15 20 25 30 35
Prob
aility
Distance soil vapor probe and contamination (ft.)
y ( )Probability < 100 (KM)Probability < 50 (KM)
20
25
30
)
Oxygen vs. Distance ‐ NAPL (UST only)
1.E+05
1.E+06
1.E+07
(ug/m3)
Xylenes vs. Distance ‐ NAPL (UST only)
> DL
< DL
RBC
10
15
20
Oxygen Co
nc. (%)
1.E+01
1.E+02
1.E+03
1.E+04
nes Vapor Con
c. RBCv
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0
5
‐10 10 30 50
O
Distance soil vapor probe and contamination (ft.)
1.E‐01
1.E+00
. 0
‐10 10 30 50
Xylen
Distance soil vapor probe and contamination (ft.)
VERTICAL DISTANCE METHOD – NAPL (UST sites)
1.E+05
1.E+06
1.E+07
or Con
c.
C9‐12 Aliphatic vs. Distance ‐ NAPL (UST only)
> DL
< DL
RBC1.E+06
1.E+07
1.E+08
or Con
c.
C5‐C8 Aliphatic vs. Distance ‐NAPL (UST only)
> DL
< DL
1.E+02
1.E+03
1.E+04
12 Alip
hatic Vap
(ug/m3)
RBCv
1.E+02
1.E+03
1.E+04
1.E+05
8 Alip
hatic Vapo
(ug/m3) RBCv
1.E+00
1.E+01
‐10 10 30 50
C9‐1
Distance soil vapor probe and contamination (ft.)
1.E+00
1.E+01
‐10 10 30 50
C5‐C8
Distance soil vapor probe and contamination (ft.)
1 E+04
1.E+05
1.E+06
por C
onc.
C9‐C10 Aromatic vs. Distance ‐ NAPL (UST only)
> DL
< DL1.E+05
1.E+06
1.E+07
(ug/m3)
Hexane vs. Distance ‐ NAPL (UST only)
RBCv
RBCv
1.E+02
1.E+03
1.E+04
10 Alip
hatic Vap
(ug/m3)
1.E+01
1.E+02
1.E+03
1.E+04
ane Vapor Con
c.
> DL
< DL
RBCv
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1.E+00
1.E+01
‐10 10 30 50
C9‐C1
Distance soil vapor probe and contamination (ft.)
1.E‐01
1.E+00
‐10 0 10 20 30
Hexa
Distance soil vapor probe and contamination (ft.)
VERTICAL DISTANCE METHOD – NAPL (all sites)
44 sites560 data points
1 E 05
1.E+06
1.E+07
1.E+08
g/m3)
Benzene vs. Distance ‐NAPL (all)
> DL
< DL
90
100
Threshold
Benzene Conditional Probability ‐NAPL (all)
1 E+01
1.E+02
1.E+03
1.E+04
1.E+05
Vapor Con
c. (ug
60
70
80
y Vapo
r Con
c. < T
Probability < 100 (1/2DL)Probability < 50 (1/2DL)
1.E‐01
1.E+00
1.E+01
‐10 10 30 50
Ben
zene
Distance soil vapor probe and contamination (ft.)
40
50
0 10 20 30 40
Prob
abilit
Distance soil vapor probe and contamination (ft.)
Probability 50 (1/2DL)Probability < 100 (KM)Probability < 50 (KM)
20
25
30
)
Oxygen vs. Distance ‐ NAPL (all)
1.E+05
1.E+06
1.E+07
g/m3)
Xylenes vs. Distance ‐ NAPL (all)
> DL
< DL
RBC
10
15
20
Oxygen Co
nc. (%)
1.E+01
1.E+02
1.E+03
1.E+04
s Vapo
r Con
c. (ug RBCv
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0
5
‐10 10 30 50
O
Distance soil vapor probe & contamination (ft.)
1.E‐01
1.E+00
‐10 10 30 50
Xylene
s
Distance soil vapor probe and contamination (ft.)
VERTICAL DISTANCE METHOD – NAPL (all sites) – EFFECT SURFACE COVER
100
d
Benzene Probability Different Surface Cover ‐ NAPL (all)
25Oxygen for Different Surface Cover ‐ NAPL (all)
80
90
nc.< Th
reshold
15
20
tration (%
)
60
70
ility vap
or C
on
Probability < 100 ug/m3 ‐ Building Scenario
10
gen Concent
40
50
0 10 20 30 40
Probab
i y g g
Probability < 100 ug/m3 ‐Ground Cover Scenario
Probability < 100 ug/m3 ‐ Pavement Scenario0
5
‐10 0 10 20 30 40 50Oxyg
O2‐ BuildingO2‐GroundO2‐ Pavement
Distance soil vapor probe and contamination (ft) Distance soil vapor probe and contamination (ft)
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VERTICAL DISTANCE METHOD - SUMMARY
Dissolved Source
LNAPL Source-UST sites
LNAPL-All sites
Oxygen Most O2 conc. > 4% and no
O2 < 1% to 6 ft separation
O2 < 1% to 11 ft separation> 4%, and no
O2 < 1% separation separation
Benzene (100 ug/m3
PKM > 97% for Ds = 0 ft
PKM ~ 100% for Ds = 15 ft
PKM > 90% @ 15 ft and ~ 95% @ 30 ft
threshold) Benzene (50 ug/m3 threshold)
PKM > 94% to 95%, for Ds = 0 ft to 5 ft
PKM ~ 100% for Ds = 15 ft
PKM > > 90% @ 15 ft and ~ 95% @ 30 ftthreshold) ft to 5 ft 30 ft
Xylenes Ds <= 3 ft Ds <= 11 ft Ds = 12 ft Hexane Ds = 0 ft Ds <= 4 ft N/A C5-8 Ali Ds <= 3 ft Ds <= 3 ft N/AC5-8 Ali Ds <= 3 ft Ds <= 3 ft N/AC9-12 Ali Ds = 0 ft Ds < = 2 ft N/A C9-10 Aro Ds = 0 ft Ds <= 2 ft N/A Ds = separation distanceDs = Separation distance where concentration less than threshold
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pDs = Separation distance where concentration less than threshold
CLEAN SOIL METHOD - DISSOLVED
30p of
Thickness Clean Soil (Davis Method) ‐ Dissolved
Thickness Clean Soil Attenuate Benzene< Threshold ‐Method 1
20
25
l (from
top
n) (ft)
Benzene < Threshold ‐Method 1Thickness Clean Soil Attenuate Benzene < Threshold ‐Method 2Thickness Soil Where Benzene Not Attenuated < Threshold
10
15
Clean Soi
amination
5
10
ckne
ss of
cont
01 10 100 1000 10000 100000
Thi
Benzene Groundwater Conc. (ug/L)
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CLEAN SOIL METHOD – LNAPL (UST)
30p of
Thickness Clean Soil (Davis ) ‐ NAPL (UST only)Thickness Clean Soil Attenuate Benzene < Threshold ‐Method 1hi k l il
20
25
l (from
top
n (ft)
Thickness Clean Soil Attenuate Benzene < Threshold ‐Method 2Thickness Soil Where Benzene Not Attenuated < Threshold
10
15
Clean Soi
taminatio
5
10
ickness of
cont
01 10 100 1000 10000 100000
Thi
Benzene Groundwater Conc. (ug/L)
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CLEAN SOIL METHOD – LNAPL (All)
30op
of
Thickness Clean Soil (Davis Method) ‐NAPL (all)Thickness Clean Soil Attenuate Benzene < Threshold ‐ Method 1
20
25
il (from to
on (ft)
Thickness Clean Soil Attenuate Benzene < Threshold ‐ Method 2Thickness Soil Where Benzene Not Attenuated < Threshold
10
15
f Clean
Soi
taminatio Not Attenuated < Threshold
5
10
ickness of
cont
01 10 100 1000 10000 100000
Th
Benzene Groundwater Conc. (ug/L)
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CLEAN SOIL METHOD – SUMMARY
95th Percentile Clean Soil
ThicknessSource
Scenario and Facility Type
Number Sites
Number Data Points
Method 1 Method 2
y ypDissolved 47 170 10.0 5.4
LNAPL (UST only)
53 172 13.9 13.5 only)
LNAPL (all facility)
60 216 20.0 16.2
Note: The above statistics include site data where no benzene groundwater concentration was available
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CONCLUSIONS
Natural attenuation of PHC vapors provides opportunity for better screening approachesg ppKey factor is whether LNAPL or dissolved sourceStatistical analysis of empirical data supports vertical exclusion distance approach of 5 ft for dissolved, 15 ft for LNAPL UST sites, and 30 ft for LNAPL all sitesAnalysis of aromatic and aliphatic data shows thatAnalysis of aromatic and aliphatic data shows that benzene is the risk driver
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CONCLUSIONS (cont.)
Exclusion distance framework requires supporting protocol for identifying LNAPL sites – given weak correlation y g gbetween dissolved and soil vapor concentrations, suggest groundwater benzene concentrations should not be primary line of evidenceprimary line of evidenceSurface cover type appears to have an effect on benzene vapor attenuation and oxygen concentrations, when data for all facility types includedInclusionary factors include large buildings/capping effect, gasoline containing likely higher quantities ethanol (subjectgasoline containing likely higher quantities ethanol (subject to further research), preferential pathways, possibly high organic content (peat) soils
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2,2,4-Trimethylpentane – NAPL (all)
1 E+07
1.E+08/m
3)224 Trimethylpentane vs. Distance ‐NAPL (all)
> DL
1.E+05
1.E+06
1.E+07
or Con
c. (u
g/
< DL
1.E+03
1.E+04
1.E 05
entane
Vapo
1.E+01
1.E+02
Trim
ethylpe
1.E+00‐10 0 10 20 30 40 50 60
224 T
Distance between soil vapor probe and contamination (ft.)
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METHANE vs. BENZENE VAPOR
1 E+08Methane vs. Benzene Vapor ‐ LNAPL (all)
SiteSource
typeFacility
type
CH4 < 20% LEL (1% V/V)
CH4 > 20% LEL (1% V/V)
CH4 > 100% LEL (5% V/V)
Al d L UST Y
1.E+05
1.E+06
1.E+07
1.E+08
c.(ug/m3)
Alameda L UST YesCoachella L Refinery YesHuntington Beach L UST YesNewport Beach L/D UST YesFormer Chevron Stn L/D UST YesPaulsboro L/D Terminal YesGas & Go #7 L/D UST Yes
1.E+02
1.E+03
1.E+04
Vapo
r Co
nc
Gas & Go # / US esHal's Chevron L/D UST Yes#102 Chevron L/D UST YesSanta Clara L/D UST Yes7-Eleven #23387 L UST YesMilo L/D UST YesCF #1803 L/D UST YesB i k L/D UST Y
1.E‐01
1.E+00
1.E+01
Ben
zene
V Berwick L/D UST YesLeeds L/D UST YesSouth Portland L/D UST YesPortland-Forest_Ave L/D UST YesCF #1839 L/D UST YesSaco L/D UST YesLewiston L/D UST Yes
0.0001 0.001 0.01 0.1 1 10 100Methane (%)
Lewiston L/D UST YesNorth Windham L/D UST YesAugusta D UST YesNorth Battleford L/D UST Yes
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PAULSBORO, NJ (Roggemans, 2002)
Building
Area 1AMethod 1: 19’-8 = 11’Method 2: 19 – (12+8)/2 = 9’
Site D19’-8 = >11’
0
Feet Below Grade Area 2
(Site D)
Area 1A
Method 2: 19 (12+8)/2 9
0
5519.6 % 19.1 %
24’
10340,000
38,000
Sand Soil
240,000
5 5
390,000
3.5 %
1.0 %
19.2 %
6.0 %
19.5 %
11.0 %
8’
12’19’
Benzene in GW 9,600 ug/L to
LNAPL
20
160,000500,000 630,0001.0 %6.0 % 6.1 %
16’
DATA ANALYSIS
Primary Chemicals EvaluatedBenzene, Xylenes, yHexaneMADEP fractions (C5-8, C9-12 aliphatics, C9-10
ti ) & TPHaromatics) & TPH2,2,4-Trimethylpentane (iso-octane)Fixed gases (O2 CO2 CH4)Fixed gases (O2, CO2, CH4)
Scenarios EvaluatedDissolved (all facilities but mostly UST)( y )LNAPL (UST only)LNAPL (all facilities)
March 27, 2012
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