9001_UnionCoMSWLF_LFGAssmt_DIN27054_20161111

-i- Landfill Gas Assessment Report
November 11, 2016

TABLE OF CONTENTS

1.0 INTRODUCTION..............................................................................................................1
1.1 Project Information ................................................................................................. 1
1.2 Background ............................................................................................................. 1
1.3 Vadose Zone Soil Gas Evaluation .......................................................................... 2
1.4 Headspace Gas Sampling in Groundwater Monitoring Well MW-1A ................... 3
2.0 DATA EVALUATION ......................................................................................................4
2.1 Comparison of Soil Gas and Well Headspace Data................................................ 4
2.2 Evaluation of Observed and Calculated Equilibrium Soil and Well
Headspace Data ....................................................................................................... 5
3.0 FINDINGS ..........................................................................................................................7
4.0 RECOMMENDATIONS ...................................................................................................9

FIGURES
Attached
Figure 1 – Site Location Map
Figure 2 – Soil Gas Probe and Well Location Map

TABLES

Attached
Table 1 – Soil Gas and Groundwater Monitoring Well MW-1A Headspace Vapor Data
Table 2 – Calculated Equilibrium Groundwater VOC Concentrations from Soil Gas VOC
Concentrations
Table 3 – Comparison of Observed and Equilibrium Soil Gas and Groundwater Concentrations
to Predict Direction of Partitioning of VOCs

APPENDICES

Appendix A – Laboratory Analytical Data Report

-1- Limited Soil Gas Assessment Report November 11, 2016

1.0 INTRODUCTION

1.1 PROJECT INFORMATION

Report Title: Soil Gas Assessment Report

Project Site: Union County NC Landfill 2125 Austin Chaney Road
Wingate, NC 28174
Facility Permit No. 90-01

Facility Owner/Operator: Union County Department of Public Works
500 N. Main Street, Suite 500
Monroe, NC 28112

County Representative: Ron Gilkerson, Solid Waste Division Director Union County Department of Public Works

Consultant: Civil & Environmental Consultants, Inc.
1900 Center Park Drive, Suite A
Charlotte. NC 28217
Consultant Contact: Edward H. Stephens, P.G. #1031

1.2 BACKGROUND

Union County owns and operates a Solid Waste Management Facility in Wingate, North
Carolina. A site vicinity map is provided in Figure 1. The Solid Waste Facility contains a closed
unlined Municipal Solid Waste (MSW) Landfill and an active Construction and Demolition
(C&D) Landfill. The North Carolina Solid Waste Management Rules 15A NCAC 13B require
that Union County monitor the quality of groundwater and surface water at the Union County
Solid Waste Management Facility in accordance with an approved Groundwater Monitoring
Plan, and to monitor for potential migrating landfill gas in accordance with an approved Methane
Monitoring Plan.

-2- Limited Soil Gas Assessment Report November 11, 2016

Low-level volatile organic compounds (VOCs) have been detected in groundwater samples from
monitoring well MW-1A, which is situated hydraulically upgradient of the landfill waste
disposal area, during recent landfill monitoring events. These detections were reported to the
North Carolina Department of Environmental Quality (NCDEQ) Solid Waste Compliance Unit
in past semi-annual monitoring reports. During a regulatory inspection of the landfill facility on
July 6, 2016, the NCDEQ Hydrogeologist requested that a “quick” soil gas assessment be
conducted in the area of the site monitored by MW-1A to determine whether landfill gas
migration may be occurring between the landfill waste boundary and MW-1A.

1.3 VADOSE ZONE SOIL GAS EVALUATION

The scope of the evaluation included the installation of three temporary soil gas sampling points
and subsequent collection of soil gas samples for laboratory analyses of targeted constituents.
As depicted on Figure 2, soil gas sampling points were located within the vadose zone between
the landfill waste disposal area and upgradient groundwater monitoring well MW-1A. The
initial approach for the vadose zone sampling was to collect soil gas from approximately one to
two feet above the static water table. The targeted sampling depth was interpolated to be
approximately 25 feet based on recent water level gauging in MW-1A. A Geoprobe® 7822DT
using direct push technology (DPT) was employed to advance the soil borings to install the soil
gas probes. DPT refusal in the weathered Slate Belt mudstone was encountered in the borings at
depths from approximately 8.75 to 12 feet below ground surface. Thus, soil gas sampling points
were set at these depths. The subsurface materials encountered were gray to brown to yellow
mottled clayey silts to silty clays.

At each selected sampling location, a pilot hole was advanced using Geoprobe DPT to facilitate
the installation of a soil gas sampling tip and tubing. A specially designed stainless steel vapor
sampling tip was installed at the bottom of the soil boring. Teflon tubing (1/4-in OD) was
connected to each tip and extended to above the ground surface to allow for the collection of a
soil gas sample. Filter sand was placed in the annular space around the vapor sampling tip to one
foot above the tip. The remainder of the open soil boring was sealed with hydrated bentonite.

-3- Limited Soil Gas Assessment Report November 11, 2016

The temporary soil gas sampling probes were then marked with high-visibility traffic cones, and
the sampling points were allowed to equilibrate several days prior to sample collection.

Prior to each sample collection, CEC used a hand pump to evacuate at least three tubing volumes
of air from each soil gas probe. Soil gas sampling was performed at a flow rate of approximately
200 milliliters per minute to limit the potential for short-circuiting. Soil gas samples were
collected from each probe using 1.4 L Summa canisters and were subsequently submitted to
Enthalpy Analytical, Inc. for analyses of methane, carbon dioxide, carbon monoxide, hydrogen,
nitrogen, and oxygen by ASTM D1946-90 Canister Analysis and low-level VOC analysis by
EPA Method TO-15. The soil gas samples were transported under chain-of-custody protocol to
the analytical laboratory

1.4 HEADSPACE GAS SAMPLING IN GROUNDWATER MONITORING WELL
MW-1A

A gas sample was also collected from the well headspace of MW-1A in which VOCs have been
detected. Plastic tubing was lowered into the groundwater monitoring to a few feet above the
gauged water level to collect the well headspace sample. The sampling flow rate was limited to
approximately 200 milliliters per minute into a 1.4 L Summa canister. This canister was
submitted along with the soil gas samples accompanied by a chain-of-custody record to Enthalpy
Analytical, Inc. for analyses of methane, carbon dioxide, carbon monoxide, hydrogen, nitrogen,
and oxygen using ASTM D1946-90 Canister Analysis and low-level VOC analysis using EPA
Method TO-15.

-4- Limited Soil Gas Assessment Report November 11, 2016

2.0 DATA EVALUATION

2.1 COMPARISON OF SOIL GAS AND WELL HEADSPACE DATA

The laboratory analytical data detections for the soil gas and well headspace samples are
tabulated in Table 1. Elevated methane and carbon dioxide were detected in the soil gas
samples. However, methane and carbon dioxide were not detected in the well headspace sample
from groundwater monitoring well MW-1A. The absence of elevated methane and carbon
dioxide in the well headspace sample could indicate that 1) MW-1A is not impacted by landfill
gas, or 2) the well screen in MW-1A is below the water table such that landfill gas cannot enter
the well headspace via the vadose zone. A well construction record could not be located for
MW-1A. However, recent well depth and water level gauging provided respective
measurements of 50 feet and 29 feet below ground surface. The screen interval is not likely 20
feet, so it would appear that the well has limited to no headspace directly in contact with the
vadose zone.

As shown in Table 1, similar VOCs where detected in the MW-1A headspace sample as were
identified in the soil gas samples. Chloromethane, ethyl acetate, methyl methacrylate, 2-
hexanone, styrene, 1,3-dichlorobenzene, and naphthalene were detected in the well headspace
sample but not in the soil gas samples. Conversely, 1,3-butadiene and methylene chloride were
not detected in the well headspace sample yet were detected in at least two soil gas samples. In
general, the VOCs detected in the soil gas samples at the most elevated concentrations
correspond with the VOCs historically detected in the aqueous phase in MW-1A. These VOCs
include benzene, dichlorodifluoromethane, 1,1-dichloroethane, cis-1,2-dichloroethene,
tetrachloroethene, trichloroethene, and vinyl chloride.

Observed VOC gas concentrations in the well headspace sample are generally one to two orders
of magnitude lower that the soil gas VOC concentrations. As provided in Table 2, calculated
equilibrium gas concentrations from VOC concentrations detected in the MW-1A groundwater
sample multiplied by the respective Henry’s Constant results indicates that the observed well
headspace gas concentrations are not high enough to have resulted in the observed groundwater

-5- Limited Soil Gas Assessment Report November 11, 2016

concentrations as calculated with the equilibrium air-water partition coefficients. The low level
VOC gas concentrations may be the result of dilution within the well headspace. It seems likely
that the headspace gas concentrations would be higher if the gas sample was collected from a
finite interval immediately above the groundwater surface in the well.

2.2 EVALUATION OF OBSERVED AND CALCULATED EQUILIBRIUM SOIL AND WELL HEADSPACE DATA
In the attached Table 2, the air-water partition coefficients, also known as Henry’s Law
constants, for the selected VOCs were used to calculate the equilibrium groundwater
concentration (EGWC) of the compound as a result of interaction with the observed soil gas
concentration (OGC) either in the groundwater well headspace or the soil gas probes. The
EGWC was compared with the respective observed groundwater concentration (OGWC)
detected in MW-1A during the most recent May 2016 monitoring event.

EGWCs calculated for the selected compounds detected in the nearest soil gas probe (SGP-1)
indicate a similar fingerprint as the OGWCs previously detected in MW-1A. Similar compounds
and higher observed soil gas concentrations for several VOCs were observed in SGP-3 also
located upgradient of the landfill waste area yet downgradient of SGP-1 and MW-1A and closer
to the landfill waste area. These data do not necessarily indicate that landfill gas is the source of
the groundwater impacts in MW-1A; however, the distribution of the soil gas data does indicate
a potential that landfill gas is a likely source of the groundwater VOCs.

If we assume that the system is at disequilibrium but tends toward equilibrium, then comparing
the observed gas concentration (OGC) with the calculated equilibrium gas concentration (EGC),
which is the observed groundwater concentration (OGWC) multiplied by the respective Henry’s
Constant (H), can provide an indication of the direction of VOC partitioning (Morris, H.H., The
Potential for Landfill Gas to Impact Ground Water Quality). Several of the predominant VOCs
that have been previously detected in the area groundwater and were also detected in the soil gas
samples are evaluated in Table 3. The Table 3 comparison evaluation shows for several VOCs
(e.g., trichloroethene, cis-1,2-dichloroethene, and benzene) that partitioning of VOCs from the
soil gas to groundwater is indicated by the sample data. Also, the comparisons for 1,1-

-6- Limited Soil Gas Assessment Report November 11, 2016

dichloroethane and tetrachloroethene indicate similar orders of concentrations that appear to
show the potential for partitioning from soil gas to groundwater. The comparisons for other
detected VOCs (e.g., dichlorodifluoromethane and vinyl chloride) indicate partitioning of VOCs
from groundwater to soil gas. The conclusions of this evaluation are mixed; however, it is clear
that the VOC concentrations detected in the soil gas samples are high enough to have resulted in
the observed groundwater concentrations as calculated with the equilibrium air-water partition
coefficients.

-7- Limited Soil Gas Assessment Report November 11, 2016

3.0 FINDINGS

The following findings are drawn from our evaluation of the landfill gas and groundwater quality
data:

• Similar VOCs where detected in the soil gas probes and groundwater well MW-1A
headspace samples. The detected VOCs with typically the most elevated concentrations
were propylene, benzene, hexane, dichlorodifluoromethane, 1,1-dichloroethane, cis-1,2-
dichloroethene, tetrachloroethene, trichloroethene, and vinyl chloride.

• Soil gas VOC concentrations were most elevated in soil gas probe (SGP-1) located in
proximity to monitoring well MW-1A. Also noted, soil gas VOC concentrations were
significantly elevated in SGP-3, which was located approximately 30 feet from the
landfill waste disposal area and 175 feet hydraulically downgradient of MW-1A. These
data do not necessarily indicate that landfill gas is the source of the groundwater impacts
in MW-1A; however, the distribution of the soil gas data does indicate a potential that
landfill gas is a likely source of the groundwater VOCs.

• No methane or carbon dioxide was detected in the headspace gas sample collected at
MW-1A. The absence of methane and carbon dioxide in the well headspace sample is
not unexpected because the well screen in MW-1A appears to be below the water table so
that landfill gas that may occur in the vadose zone cannot migrate into the well
headspace. Also, VOC gas concentrations in the well headspace sample are generally
one to two orders of magnitude lower that the soil gas VOC concentrations. The low
level VOC gas concentrations in the well headspace sample may be the result of dilution
within the well headspace and/or due to the well screen being below the water table.

• The calculated equilibrium gas concentrations for several detected VOCs (i.e.,
trichloroethene, cis-1,2-dichloroethene, and benzene) are less than the observed gas
concentrations indicating the potential for partitioning of VOCs from the gas phase to the
aqueous phase. Also, the comparisons for 1,1-dichloroethane and tetrachloroethene

-8- Limited Soil Gas Assessment Report November 11, 2016

indicate similar orders of concentrations that appear to show the potential for partitioning
from soil gas to groundwater. The comparisons for other detected VOCs (e.g.,
dichlorodifluoromethane and vinyl chloride) indicate partitioning of VOCs from
groundwater to soil gas. The conclusions of this evaluation are mixed; however, it is
clear that the VOC concentrations detected in the soil gas samples are high enough to
have resulted in the observed groundwater concentrations as calculated with the
equilibrium air-water partition coefficients.

• A site-specific checklist is presented below based on what researchers have identified
where landfill gas may be the source of groundwater contamination.

SITE CONDITION POTENTIAL FOR LANDFILL GAS TO
IMPACT GROUNDWATER
YES NO
Presence of migrating landfill gas is confirmed in soil or landfill gas wells. x
VOCs are in some cases detected in upgradient
groundwater monitoring wells. x
Direct relationship between the landfill gas and
gases observed in the headspace of monitoring wells x
VOC detected in groundwater was either the same
compound or a degradation product of the VOC found in the landfill gas. x
Typical detected VOC parameters are associated with vapor migration in landfills x
Low levels of VOCs are detected above background values x
VOC concentrations in groundwater are reduced
during landfill mitigation
No landfill gas
mitigation is occurring at the site

-9- Limited Soil Gas Assessment Report November 11, 2016

4.0 RECOMMENDATIONS

The data collected and evaluated during this limited soil gas study indicate that significant
landfill gas concentrations exist at the southeast perimeter of the landfill waste disposal area in
the vadose zone (just above the Geoprobe DPT refusal depth of approximately 8.75 to 12 feet
below ground surface) between the buried waste mass and upgradient groundwater monitoring
well MW-1A. These data also confirm that landfill gas is migrating beyond the waste
boundaries, but not beyond the Methane Compliance Monitoring Boundary as referenced in the
facility’s Quarterly Methane Gas Monitoring Data Reports. The limited data also appear to
indicate that migrating landfill gas has impacted groundwater in the vicinity of monitoring well
MW-1A.

Due to the limited scope of the soil gas assessment, it is CEC’s opinion that gas probes should be
installed along the unused portion of the waste disposal area along the southeastern perimeter to
1) verify the presence of landfill gas within the landfill mass; 2) confirm the potential for landfill
gas to impact MW-1A; and 3) provide data to design a passive landfill gas control system, if
warranted.

FIGURES

REFERENCE
DATE:DWG SCALE:
DRAWN BY:CHECKED BY:APPROVED BY:
PROJECT NO:
FIGURE NO.:
SITE LOCATION MAP
151-7971"=5000'DECEMBER 2015
PNP EHS EHS 1
UNION COUNTY LANDFILL
2125 AUSTIN CHANEY ROAD
WINGATE, NORTH CAROLINA
www.cecinc.com
1900 Center Park Drive - Suite A - Charlotte, NC 28217
3KÃ)D[
NORTH
DATE:DWG SCALE:
DRAWN BY:CHECKED BY:APPROVED BY:
PROJECT NO:
ATTACHMENT:
SOIL GAS ASSESSMENT
WELL PROBE LOCATION MAP
151-7971"=400'JULY 2016
PNP EHS EHS 2
UNION COUNTY LANDFILL
2125 AUSTIN CHANEY ROAD
WINGATE, NORTH CAROLINA
REFERENCE
www.cecinc.com
1900 Center Park Drive - Suite A - Charlotte, NC 28217
Ph: 980.237.0373 · Fax: [phone]
NORTH
LEGEND

TABLES

Table 1
Soil Gas and Groundwater Monitoring Well MW-1A Headspace Vapor Data
Union County Landfill
CEC Project No. 151-797.0005
Carbon Dioxide
Carbon Monoxide
Hydrogen
Methane
Nitrogen
Oxygen
ppbv µg/m3 ppbv µg/m3 ppbv µg/m3 ppbv µg/m3
Propylene 1,627 2,800 3,639 6,262 2,107 3,625 30.8 53.0
Dichlorodifluoromethane (Freon 12) 152 754 15.2 75.1 171 846 50.0 247
Freon 114 189 1,323 315 2,203 95.4 667 4.89 34.2
Chloromethane ND ND ND ND ND ND 3.34 6.9
1,3-Butadiene 19.6 43.4 8.44 18.7 11.8 26.2 ND ND
Vinyl Chloride 1,950 4,984 201 515 613 1,568 3.37 8.6
Bromomethane ND ND ND ND ND ND ND ND
Chloroethane 29.7 78.4 3.07 8.09 16.9 44.5 1.33 3.51
Trichlorofluoromethane (Freon 11) ND ND ND ND 7.4 41.6 0.254 1.43
Ethanol 285 537 813 1,532 80.8 152 26.5 49.8
Acrolein ND ND ND ND ND ND ND ND
Trichlorotrifluoroethane (Freon 113) ND ND ND ND ND ND ND ND
1,1-Dichloroethene 40.2 160 ND ND 10.3 40.7 5.09 20.2
Acetone 52.5 125 99.6 237 40.5 96.1 305 724
Carbon Disulfide 8.14 25.4 17.4 54.2 14.3 44.7 0.532 1.66
Isopropyl Alcohol 20.6 50.6 10.8 26.6 16.0 39.3 2.13 5.23
Acetonitrile 46.2 77.5 27.4 46.0 130 218 2.17 3.64
Methylene Chloride 4.7 16.3 ND ND 285 989 ND ND
trans-1,2-Dichoroethene 172 682 23.9 94.9 126 500 2.6 10.3
Hexane 350 1,232 622 2,194 189 667 11.6 40.9
1,1-Dichloroethane 106 428 4.44 18 113 456 29.1 118
Ethyl Acetate ND ND ND ND ND ND 4.23 15.2
Vinyl Acetate ND ND ND ND ND ND ND ND
cis-1,2,-Dichloroethene 3,864 15,319 373 1,478 10,701 42,428 259 1,027
2-Butanone (MEK) ND ND ND ND ND ND ND ND
Chloroform 2.32 11.3 ND ND 6.63 32.4 0.708 3.46
Tetrahydrofuran ND ND ND ND ND ND ND ND
Cyclohexane 289 993 480 1,653 120 412 30.7 106
Carbon Tetrachloride ND ND ND ND ND ND ND ND
Benzene 207 661 280 894 808 2,581 28.4 90.7
2,2,4-Trimethylpentane 244 1,142 486 2,270 140 654 8.75 40.9
Heptane 627 2,569 788 3,231 197 809 0.762 3.12
Trichloroethene 1,745 9,375 100 538 804 4,321 442 2,375
Methyl Methacrylate ND ND ND ND ND ND 1.76 7.19
1,2-Dichloropropane ND ND ND ND ND ND ND ND
Methyl Isobutyl Ketone 90.4 370 ND ND ND ND 0.193 0.79
Toluene 60.4 228 330 1,245 95.4 360 814 3,066
Tetrachloroethene 117 793 51.8 352 402 2,727 228 1,547
2-Hexanone ND ND ND ND ND ND 0.216 0.884
Chlorobenzene 21.1 97.1 3.65 16.8 8.28 38.1 8.07 37.1
Ethylbenzene 14.8 64.2 10.6 46.1 127 552 1.79 7.77
Styrene ND ND ND ND ND ND 0.367 1.56
m-/p-Xylenes 60.9 264 31.1 135 828 3,597 1.77 7.68
o-Xylene 25.6 111 11.3 48.9 400 1,737 0.715 3.1
1,1,2,2-Tetrachloroethane ND ND ND ND 14.5 100 ND ND
4-Ethyltoluene ND ND ND ND 11.1 54.5 ND ND
2-Chlorotoluene ND ND 5.43 28.1 ND ND ND ND
1,2,4-Trimethylbenzene 2.21 10.9 ND ND 101 498 0.324 1.59
1,3,5-Trimethylbenzene ND ND ND ND 95.5 470 ND ND
1,3-Dichlorobenzene ND ND ND ND ND ND 0.228 1.37
1,4-Dichlorobenzene 2.55 15.3 ND ND 10.1 60.9 0.413 2.48
Naphthalene ND ND ND ND ND ND 0.37 1.94
ppbv = parts per billion per volume
µg/m3 = micrograms per cubic meter
28.0
1.06 J
SGP-1 SGP-2
40.0
0.110 ND
0.247 ND
6.88
40.5
0.828 J
13.1
MW-1ASGP-3
46.8
0.109 ND
0.246 ND
Percent (%)
17.8
35.5
0.213 ND
0.478 ND
5.67
43.5
1.55 J
0.640 J
0.101 ND
0.227 ND
0.0825 ND
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,
2
0
0

3
4
.
8

0
.
0
5

1
1
1
.
0
3

0
.
0
0

1
0
.
7
2

0
.
1
4

3
0
7
.
5
0

0
.
0
0

7
.
4
4

5
2
.
4
tr
a
n
s
-
1
,
2
-
D
i
c
h
o
r
o
e
t
h
e
n
e

1
7
2

6
8
2

2
3
.
9

9
4
.
9

1
2
6

5
0
0

2
.
6

1
0
.
3

7
1
.
0

1
5
1

2
.
4
2

1
.
1
4

0
.
3
4

0
.
1
6

1
.
7
7

0
.
8
3

0
.
0
4

0
.
0
2

N
D
Be
n
z
e
n
e

2
0
7

6
6
1

2
8
0

8
9
4

8
0
8

2
,
5
8
1

2
8
.
4

9
0
.
7

6
9
.
9

6
9
.
5

2
.
9
6

2
.
9
8

4
.
0
1

4
.
0
3

1
1
.
5
6

1
1
.
6
3

0
.
4
1

0
.
4
1

1
.
8
To
l
u
e
n
e

6
0
.
4

2
2
8

3
3
0

1
,
2
4
5

9
5
.
4

3
6
0

8
1
4

3
,
0
6
6

7
1
.
3

7
0
.
0

0
.
8
5

0
.
8
6

4
.
6
3

4
.
7
1

1
.
3
4

1
.
3
6

1
1
.
4
2

1
1
.
6
3

N
D
Tr
i
c
h
l
o
r
o
e
t
h
e
n
e

1
,
7
4
5

9
,
3
7
5

1
0
0

5
3
8

8
0
4

4
,
3
2
1

4
4
2

2
,
3
7
5

8
2
.
5

6
9
.
3

2
1
.
1
5

2
5
.
1
8

1
.
2
1

1
.
4
4

9
.
7
5

1
1
.
6
0

5
.
3
6

6
.
3
8

2
3
Te
t
r
a
c
h
l
o
r
o
e
t
h
e
n
e

1
1
7

7
9
3

5
1
.
8

3
5
2

4
0
2

2
,
7
2
7

2
2
8

1
,
5
4
7

1
6
.
2

5
8
.
0

7
.
2
2

2
.
0
2

3
.
2
0

0
.
8
9

2
4
.
8
1

6
.
9
3

1
4
.
0
7

3
.
9
3

7
.
5
Et
h
y
l
b
e
n
z
e
n
e

1
4
.
8

6
4
.
2

1
0
.
6

4
6
.
1

1
2
7

5
5
2

1
.
7
9

7
.
7
7

7
7
.
9

7
0
.
4

0
.
1
9

0
.
2
1

0
.
1
4

0
.
1
5

1
.
6
3

1
.
8
0

0
.
0
2

0
.
0
3

N
D
m-
/
p
-
X
y
l
e
n
e
s

6
0
.
9

2
6
4

3
1
.
1

1
3
5

8
2
8

3
,
5
9
7

1
.
7
7

7
.
6
8
ND
o-
X
y
l
e
n
e

2
5
.
6

1
1
1

1
1
.
3

4
8
.
9

4
0
0

1
,
7
3
7

0
.
7
2

3
.
1
ND
To
t
a
l

X
y
l
e
n
e

8
6
.
5

3
7
5

4
2
.
4

1
8
3
.
9

1
,
2
2
8

5
,
3
3
4

2
.
4
9

1
0
.
7
8

7
5
.
2
48
.
8
1.
1
5

1
.
7
7

0
.
5
6

0
.
8
7

1
6
.
3
3

2
5
.
1
6

0
.
0
3

0
.
0
5

N
D
pp
b
v

=

p
a
r
t
s

p
e
r

b
i
l
l
i
o
n

p
e
r

v
o
l
u
m
e
µg
/
m
3

=

m
i
c
r
o
g
r
a
m
s

p
e
r

c
u
b
i
c

m
e
t
e
r
µg
/
L

=

m
i
c
r
o
g
r
a
m
s

p
e
r

l
i
t
e
r
Eq
u
i
l
i
b
r
i
u
m

G
W

C
o
n
c
e
n
t
r
a
t
i
o
n
s

=

O
b
s
e
r
v
e
d

S
o
i
l

G
a
s

C
o
n
c
e
n
t
r
a
t
i
o
n

/

H
e
n
r
y
'
s

C
o
n
s
t
a
n
t
He
n
r
y
'
s

C
o
n
s
t
a
n
t

SG
P
-
1

S
G
P
-
2

S
G
P
-
3

M
W
-
1
A
Eq
u
i
l
i
b
r
i
u
m

G
W

C
o
n
c
e
n
t
r
a
t
i
o
n
s
SG
P
-
1

S
G
P
-
2

S
G
P
-
3

M
W
-
1
A
Ob
s
e
r
v
e
d

G
a
s

P
r
o
b
e

S
a
m
p
l
e

C
o
n
c
e
n
t
r
a
t
i
o
n
MW
-
1
A

H
e
a
d
s
p
a
c
e

Sa
m
p
l
e

C
o
n
c
e
n
t
r
a
t
i
o
n
Ta
b
l
e

3
Co
m
p
a
r
i
s
o
n

o
f

O
b
s
e
r
v
e
d

a
n
d

E
q
u
i
l
i
b
r
i
u
m

S
o
i
l

G
a
s

a
n
d

G
r
o
u
n
d
w
a
t
e
r

C
o
n
c
e
n
t
r
a
t
i
o
n
s
to

P
r
e
d
i
c
t

D
i
r
e
c
t
i
o
n

o
f

P
a
r
t
i
t
i
o
n
i
n
g

o
f

V
O
C
s
Un
i
o
n

C
o
u
n
t
y

L
a
n
d
f
i
l
l
CE
C

P
r
o
j
e
c
t

N
o
.

1
5
1
-
7
9
7
.
0
0
0
4
OG
W
C
Co
n
d
i
t
i
o
n

I
n
d
i
c
a
t
i
o
n

o
f

P
a
r
t
i
t
i
o
n
i
n
g
MW
-
1
A

H
c

H
r

E
G
C
c

E
G
C
r

S
G
P
-
1
SG
P
-
2

S
G
P
-
3
µg
/
L

p
p
b
v
-
L
/
µ
g

p
p
b
v
-
L
/
µ
g

p
p
b
v

p
p
b
v

p
p
b
v

p
p
b
v

p
p
b
v
Di
c
h
l
o
r
o
d
i
f
l
u
o
r
o
m
e
t
h
a
n
e

1
.
9

2
0
,
0
0
0

9
,
3
4
0

3
8
,
0
0
0

1
7
,
7
4
6

1
5
2

1
5
.
2

1
7
1

E
G
C

>

O
G
C

V
O
C
s

f
r
o
m

G
W

→ soil gas
Vi
n
y
l

C
h
l
o
r
i
d
e

1
.
6

1
,
2
7
0

2
,
4
7
0

2
,
0
3
2

3
,
9
5
2

1
,
9
5
0

2
0
1

6
1
3

E
G
C

>

O
G
C

V
O
C
s

f
r
o
m

G
W

→ soil gas
1,
1
-
D
i
c
h
l
o
r
o
e
t
h
a
n
e

2
.
5

5
9
.
0

5
3
.
9

1
4
7
.
5

1
3
4
.
8

1
0
6

4
.
4
4

1
1
3

E
G
C

>

O
G
C

V
O
C
s

f
r
o
m

G
W

→ soil gas
ci
s
-
1
,
2
,
-
D
i
c
h
l
o
r
o
e
t
h
e
n
e

5
2
.
4

7
5
,
2
0
0

3
4
.
8

3
,
9
4
0
,
4
8
0

1
,
8
2
4

3
,
8
6
4

3
7
3

1
0
,
7
0
1

E
G
C

<

O
G
C

V
O
C
s

f
r
o
m

s
o
i
l

g
a
s

→ GW
Be
n
z
e
n
e

1
.
8

6
9
.
9

6
9
.
5

1
2
5
.
8

1
2
5
.
1

2
0
7

2
8
0

8
0
8

E
G
C

<

O
G
C

V
O
C
s

f
r
o
m

s
o
i
l

g
a
s

→ GW
Tr
i
c
h
l
o
r
o
e
t
h
e
n
e

2
3

8
2
.
5

6
9
.
3

1
,
8
9
8

1
,
5
9
4

1
,
7
4
5

1
0
0

8
0
4

E
G
C

<

O
G
C

V
O
C
s

f
r
o
m

s
o
i
l

g
a
s

→ GW
Te
t
r
a
c
h
l
o
r
o
e
t
h
e
n
e

7
.
5

1
6
.
2

5
8
.
0

1
2
1
.
5

4
3
5

1
1
7

5
1
.
8

4
0
2

E
G
C

>

O
G
C

V
O
C
s

f
r
o
m

G
W

→ soil gas
if

E
G
C

>

O
G
C
,

t
h
e
n

V
O
C
s

a
r
e

p
a
r
t
i
t
i
o
n
i
n
g

f
r
o
m

t
h
e

g
r
o
u
n
d
w
a
t
e
r

t
o

t
h
e

s
o
i
l

g
a
s
,

a
n
d

if

E
G
C

<

O
G
C
,

t
h
e
n

V
O
C
s

a
r
e

p
a
r
t
i
t
i
o
n
i
n
g

f
r
o
m

t
h
e

s
o
i
l

g
a
s

t
o

t
h
e

g
r
o
u
n
d
w
a
t
e
r
.
EG
C

He
n
r
y
'
s

C
o
n
s
t
a
n
t
OG
C
As
s
u
m
i
n
g

t
h
a
t

t
h
e

s
y
s
t
e
m

i
s

a
t

d
i
s
e
q
u
i
l
i
b
r
i
u
m

b
u
t

t
e
n
d
s

t
o
w
a
r
d

e
q
u
i
l
i
b
r
i
u
m
,

t
h
e
n

c
o
m
p
a
r
i
n
g

t
h
e

o
b
s
e
r
v
e
d

a
n
d

t
h
e

e
q
u
i
l
i
b
r
i
u
m

c
o
n
ce
n
t
r
a
t
i
o
n
s

o
f

t
h
e

sa
m
e

m
e
d
i
a

(
i
.
e
.
,

g
a
s

o
r

g
r
o
u
n
d
w
a
t
e
r
)

c
a
n

p
r
o
v
i
d
e

a
n

i
n
d
i
c
a
t
i
o
n

o
f

t
h
e

d
i
r
e
c
t
i
o
n

o
f

p
a
r
t
i
t
i
o
n
i
n
g

a
s

f
o
l
l
o
w
s
:

APPENDIX A LABORATORY ANALYTICAL DATA REPORTS