FA-719_17850_CA_MRP_20230824

SUBSEQUENT MONITORING
REPORT
WARD'S CITGO (INCIDENT NO. 17850)
10236 W R LATHAM STREET
CLARKTON, BLADEN COUNTY, NORTH CAROLINA
ESP Project No. 23-00200-019

Prepared For:
North Carolina Department of Environmental Quality
Division of Waste Management
1646 Mail Service Center
Raleigh, North Carolina 27699-1646

Prepared By:
ESP Associates, Inc.
P. O. Box 7030
Charlotte, North Carolina 28241

August 24, 2023

ESP Associates, Inc.
P.O. Box 7030 • Charlotte, NC 28241
1.800.960.7317 • NC: 704.583.4949, fax [phone] • SC: 803.802.2440, fax [phone]
www.espassociates.com

August 24, 2023

Mr. Hassan Osman
North Carolina Department of Environmental Quality
Division of Waste Management
1646 Mail Service Center
Raleigh, North Carolina 27699-1646

Email: [e-mail]

Reference: SUBSEQUENT MONITORING REPORT
Ward’s Citgo (Incident #17850)
10236 W R Latham Road
Clarkton, Bladen County, North Carolina
ESP Project No. 23-00200-019

Dear Mr. Osman

ESP Associates, Inc. (ESP) is pleased to present this Subsequent Monitoring Report documenting
activities performed at the subject site, Ward’s Citgo, in accordance with North Carolina Department
of Environmental Quality (NCDEQ), Task Authorization No. 1, approved on May 22, 2023. The
subject site is located at 10236 W R Latham Road in Clarkton, Bladen County, North Carolina.

We appreciate the opportunity to provide environmental services on this project. If you should have
any questions, please do not hesitate to contact us at [phone].

Sincerely,
ESP Associates, Inc.
Matthew R. Craig Christopher J. Ward, PG, RSM
Project Manager Senior Geologist

Attachment – Subsequent Monitoring Report

TABLE OF CONTENTS

Section Page

SITE INFORMATION ..................................................................................................................... i

EXECUTIVE SUMMARY ............................................................................................................. iii

1.0 INTRODUCTION ............................................................................................................... 1
1.1 SITE SETTING ........................................................................................................... 1
1.2 SITE GEOLOGY AND HYDROGEOLOGY ................................................................. 1
1.3 SURFACE WATER ..................................................................................................... 2
1.4 WATER SUPPLY WELLS ........................................................................................... 3

2.0 SITE HISTORY .................................................................................................................. 4

3.0 FIELD ACTIVITIES ........................................................................................................... 6
3.1 WATER LEVEL GAUGING ........................................................................................ 6
3.2 GROUNDWATER SAMPLING ................................................................................... 6
3.3 FREE PRODUCT EVALUATION ................................................................................ 6
3.4 FIELD QUALITY CONTROL SAMPLING AND ANALYSIS ....................................... 7

4.0 ANALYTICAL RESULTS .................................................................................................. 8

5.0 CONCLUSIONS AND RECOMMENDATIONS ................................................................. 9

6.0 REFERENCES ................................................................................................................. 10

FIGURES
Figure 1 USGS Topographic Site Location Map
Figure 2 Site Map
Figure 3 Groundwater Elevation Map
Figure 4 Groundwater Results Map
Figure 5 Benzene Isoconcentration Map

TABLES
Table 1 Water Supply Well Information
Table 2 Monitoring Well Construction and Groundwater Elevation Data
Table 3 Summary of Groundwater Analytical Results

APPENDICES
Appendix A Tables of Previous Groundwater Elevations and Analytical Results
Appendix B Field Documentation and Photographs
Appendix C Laboratory Data Reports

Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

i

SITE INFORMATION

Date of Report: August 24, 2023
NCDEQ Incident No: 17850
NCDEQ UST No.: FA-719
Site Name: Ward’s Citgo
Site Location: 10236 W R Latham Road
Clarkton, Bladen County, NC 28433

Latitude: N 34.490474
Longitude: W -78.661626

UST Owner/ Operator: John Ward and Sampson-Bladen Oil Company
510 Commerce Street, PO Box 469,
Clinton, NC 28329
[phone]
Current Property
Owner: Mr. Woodrow Marlowe / Snake Island LLC
PO Drawer 36
Clarkton, NC 28433
Contact: Woodrow Marlowe (910-647-5521)

Current Property
Occupant: Burger Shack and an unnamed auto repair shop
[phone]

Consultant: ESP Associates, Inc.
10P.O. Box 7030
Charlotte, NC 28241
[phone]

Laboratory: Pace Analytical Services, LLC
NCDEQ No. 5342
9800 Kincey Avenue
Huntersville, NC 28028
[phone]

Release Information: Release Discovery Date: September 1994 and August 1997
Estimate Quantity: Unknown
Cause of Release: UST System
Source of Release: UST System
Currently Active Tanks: None
Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

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I, Christopher J. Ward, a Professional Geologist for ESP Associates, Inc., do certify that the
information contained in this report is correct and accurate to the best of my knowledge.

ESP Associates, Inc. is licensed to practice both geology and engineering in North Carolina. ESP
Associates, Inc.’ certification numbers are: Geology: C-556 / Engineering: F-1407
Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

iii

EXECUTIVE SUMMARY

This executive summary section provides an abbreviated reporting of our Site observations and
findings. Refer to the main text and appendices for a complete reporting of our observations and
findings.

ESP Associates, Inc. (ESP) has completed a Subsequent Monitoring Report documenting
assessment activity performed at the Ward’s Citgo site (Incident No. 17850). The site is an
approximate 0.62-acre commercial site (Tax Parcel PIN. 120605197542) located at 10236 W R
Latham Road, Clarkton, Bladen County, North Carolina. This report was completed to summarize
the findings of assessment activities performed on June 13, 2023, in accordance with North Carolina
Department of Environmental Quality (NCDEQ), Task Authorization No. 1, approved on May 22,
2023.

The work was performed as part of the State Lead Contract #N70522-D between NCDEQ and ESP.
This report was prepared in general accordance with the 15A NCAC 2L .0115 regulations and the
NCDEQ Underground Storage Tank (UST) Section Guidelines for Assessment and Corrective Action
for UST Releases, January 2021, under the supervision of Christopher J. Ward, North Carolina
registered professional geologist (North Carolina License No. 1600).

Field activities performed by ESP on June 13, 2023, included:
• Gauging static water levels in site monitoring wells MW-3 through MW-12 and free
product in MW-1. Although planned, ESP was unable to gauge MW-5 as it was destroyed
during previous UST removal. Additionally, MW-1 and MW-3 were found to be filled
with sand; thus, water level measurements were not possible; and
• Collecting groundwater samples from MW-4 through MW-12. Although planned, ESP
was unable to obtain groundwater samples from MW-3 (filled with sand) and MW-5
(previously destroyed).

Collected water samples were analyzed for volatile organic compounds (VOCs) for comparison to
both North Carolina Groundwater Quality Standards 15A NCAC 2L .0202 (2L Standards) and Gross
Contaminant Levels (GCLs).
Based on results of the above field activities and previous reporting, ESP concludes the following:
• MW-1 and MW-3 were found to be filled with sand; thus, neither water level measurements
or collection of groundwater samples were possible;
• Static water level depths ranged from 2.60 ft to 9.11 ft bTOC;
• Free product was not encountered in any of the gauged monitoring wells;
• The general direction of groundwater flow beneath the site is to the southwest, southeast,
and northeast;
• No analytes were detected at concentrations exceeding their respective GCLs;
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Ward’s Citgo (Incident #17850) August 24, 2023

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• Various analytes were detected at concentrations greater than their respective 2L
groundwater standards in MW-4, MW-6, MW-8, MW-9, and MW-12;
• No analytes were detected above 2L standards in MW-7, MW-10, or MW-11;
• A comparison of groundwater laboratory analytical results from the June 13, 2023,
sampling event to the September 30, 2021, sampling event reveals that concentrations in
site monitoring wells have remained relatively stable except for MW-12, which has shown
a continued downward trend in concentrations;
• No exceedances of GCLs have been reported since the January 16, 2018 sampling event;
and
• Due to our inability to gauge for free product in MW-1, the impact of the June 28, 2022
AFVR event at MW-1 could not be assessed.

Based on the above results, ESP offers the following recommendations:
• Continue to sample site monitoring wells on a semiannual basis to further understand
concentration trends and plume stability;
• Consider installation of replacement wells for MW-1, MW-3, and MW-5;
• Abandon compromised monitoring wells MW-1 and MW-3;
• Consider conducting an AFVR event on the MW-1 replacement well and possibly MW-9
to recover any remaining free product and further reduce constituent concentrations; and
• Install oxidation sleeves in monitoring wells MW-4, MW-6, MW-9, and MW-12 to attempt
to further reduce VOC concentrations and stabilize the contaminant plume.

Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

2

1.0 INTRODUCTION

1.1 Site Setting

The Ward’s Citgo site is an approximate 0.62-acre site (Tax Parcel PIN. 120605197542) located at
10236 W R Latham Road in Clarkton, Bladen County, North Carolina (see Figures 1 and 2). The
site is commercially developed with an approximate 1,600-square foot (sqft) building used for storing
automobiles with an attached canopy, an approximate 200 sqft building used as a restaurant, and an
approximate 200-sqft building used for storage. The site is bound to the north by a commercial
warehouse, to the east by N W R Latham Street, to the west by Green Street, and to the south by the
intersection of N W R Latham Street and Green Street.

1.2 Site Geology and Hydrogeology

Consideration of surface and subsurface drainage and geology are of interest since they provide
an indication of the direction that contamination, if present on-site or off-site, could be transported.
The site is located within the Coastal Plain Physiographic Provence. The Coastal Plain Region was
formed by deposition of unconsolidated, flat layers of sediment sourced from erosion of mountains
to the west. Sediments were deposited into varying depositional environments in accordance with
sea level changes. Most parts of the Coastal Plain Region consist of well to moderately well-
drained loamy soils. The site is underlain by the Tertiary-aged Yorktown and Duplin Formations.
Materials in the Yorktown formation consist of fossiliferous clay with varying amounts fine-
grained sand, and bluish-gray shell material commonly concentrated in lenses. Materials in the
Duplin formation consist of shelly, medium-to-coarse-grained sand and sandy marl. Soils in the
site area consist of Lynchburg fine sandy loam (Ly).

The direction and movement of groundwater through soil is generally dependent on soil type, the
presence of relict structures, and the textures of the underlying rock. Fractures, faults, folds, and
foliation planes affect the migration of groundwater in rock. No major geologic features (faults,
etc.) are present at or near the site. Groundwater typically flows in directions parallel to the ground
surface and under the influence of gravity, migrates to discharge points such as surface water
features, the toes of slopes or natural springs. Fluctuations in the depth of the water table can be
expected depending on variations in precipitation, surface water run-off and other factors.
Normally, the highest levels of the water table occur in late winter and spring and the lowest levels
occur in the late summer and fall. Based on historical data and June 13, 2023, water level
measurements, groundwater at the site is expected to flow generally to the southwest, southeast,
and northeast.

1.3 Surface Water

The only surface water feature present within 1,000 feet of the site is an unnamed intermittent stream
located approximately 800 feet south of the site (see Figure 1).
Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

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1.4 Water Supply Wells

No water supply wells have been identified as being located within 1,000 feet of the site. Two
water supply wells (i.e., TOC WSW-1 and TOC WSW-3) were identified as being located
approximately 1,100 feet to the east and 1,350 feet to the southeast, respectively (see Table 1).
These municipal water supply wells are located within a wellhead protection area that encompasses
the entire Town of Clarkton. Municipal water is reportedly available at the site and within the
Town of Clarkton.
Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

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2.0 SITE HISTORY

The following description of historical site activities was obtained from a report titled “Annual
Monitoring Report, Ward’s Citgo, Clarkton, North Carolina” dated November 2, 2021, by
Terracon Consultants Inc. (Terracon) and a report titled “Aggressive Fluid Vapor Recovery Event
Letter Report, Ward’s Citgo” dated August 4, 2022 by Terracon.
• In March 1992, the first release was discovered after laboratory analysis of monitoring
well samples revealed an increased presence of petroleum constituents.
• In September 1994, soil and groundwater samples were collected during the partial
removal of the UST system on site. Three 4,000-gallon and one 3,000-gallong USTs and
two 10,000-gallon USTs were removed during this event. Laboratory analysis indicated
the presence of Total Petroleum Hydrocarbons (TPH) and (Diesel Range Organics
(DRO) above action levels.
• In August 1997, the second release was discovered when a site check revealed cracks in
the fiberglass supply lines of a 12,000-gallon UST. The UST was left in place and
removed later as noted below.
• In 1998, monitoring wells MW-1 through MW-5 were installed and sampled. The sample
analysis was not presented when it was originally obtained, and therefore cannot be
referenced. However, it should be noted that no free product was observed inside the
wells after installation.
• On October 5, 2007, the 12,000-gallon UST was removed from the site along with 50 cu
yds of petroleum impacted soil. Monitoring wells MW-1, MW-3 and MW-4 were also
sampled. MW-2 was deemed to be lost during this event, and MW-5 was destroyed
during the process of UST removal. Laboratory analysis of the samples collected
indicated constituents above the 2L standards in MW-3 and MW-4.
• On August 20, 2009, a sampling event took place for monitoring wells MW-1 through
MW-1 along with TOC WSW-1. Free product was measured in MW-1 at a thickness of
4.83 feet. Continued efforts to locate MW-2 were unsuccessful. Laboratory analysis
indicated that benzene concentrations in MW-4 exceeded the GCL. Several other
constituents were also detected in MW-4 below their respective GCL, but above their 2L
standard.
• Between April 27 and 28, 2010, monitoring wells MW-6 through MW-9 and MW-2R to
replace the lost MW-2, were installed. The wells sampled after installation. Analysis
indicated benzene concentrations in MW-9 were above the GCL. Several constituents
were also detected above the 2L standard in all wells sampled during this event.
• On July 19, 2011, monitoring wells MW-10 and MW-11 were installed off site, across
W R Latham Street. Samples were collected from MW-2R through MW-11. MW-1 was
not sampled due to the presence of free product. MW-6 was also not locatable during this
sampling event. Sample analysis indicated benzene concentrations above the GCL were
present in MW-2R and MW-9. All wells, except for MW-11, contained constituents
above 2L standards.
Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

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• On July 25, 2011, Terracon mobilized to perform a receptor survey of the site.
• On July 23, 2014, Terracon mobilized to sample monitoring wells MW-1 through MW-
11 and a recently discovered well marked MW-18. MW-2R was not able to be located.
• Between November 10 and 14, 2014, a mobile multi-phase extraction (MMPE) event
was performed over the course of 96 hours on MW-1, MW-4, MW-6, MW-8, and MW-
9. An estimated 79.37 gallons of gasoline were recovered. Terracon re-mobilized on
November 20, 2014, to gauge the free product in MW-1, and found the thickness to be
0.01 feet.
• On June 15, 2015, Terracon mobilized to remove the remaining tanks in the UST network
on site. While Terracon was aware of petroleum impacted soil around the tanks,
excavation of the soil was not possible due to the proximity of the tanks to the commercial
structure on site.
• In January 2018, MW-18 was closed and abandoned by another investigation team, and
MW-2R was considered destroyed, as it had not been located since 2012.
• Between April 16 and 20, 2018, a 96-hour MMPE event was performed on MW-1, MW-
6, MW-8, MW-9, and MW-12. During the event, 34.32 gallons of dissolved gasoline
were removed along with 12 gallons of free product.
• On June 28, 2022, HERR performed an AFVR event for 8 hours using monitoring well
MW-1 for extraction. Terracon estimated that 0.035 gallons of gasoline were recovered
during the event.

Historical groundwater elevations and analytical results are provided in Appendix A.
Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

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3.0 FIELD ACTIVITIES

Field activities performed by ESP on June 13, 2023, included:
• Gauging static water levels in site monitoring wells MW-3 through MW-12 and free
product in MW-1. Although planned, ESP was unable to gauge MW-5 as it was destroyed
during previous UST removal. Additionally, MW-1 and MW-3 were found to be filled
with sand; thus, water level measurements were not possible; and
• Collecting groundwater samples from MW-4 through MW-12. Although planned, ESP
was unable to obtain groundwater samples from MW-3 (filled with sand) and MW-5
(previously destroyed).

Sample locations are depicted on Figure 2. Field logbook entries along with water level survey,
groundwater sampling, and field instrument calibration forms were completed in the field to
document site activities (see Appendix B). Photographs are also provided in Appendix B. Details
of field activities are provided below.

3.1 Water Level Gauging

On June 13, 2023, prior to purging or collecting groundwater samples, depth to groundwater from
the top of casing (TOC) within each monitoring well was measured and recorded using a
decontaminated electronic water level meter. The water level measurements were collected by
first removing covers and plunger caps from all site monitoring wells and allowing water within
the wells to stabilize. The electronic water level meter probe was then lowered into the well and
the depth to water measured relative to the well’s TOC.

As noted on Table 2, static water level depths ranged from 2.60 ft to 9.11 ft below top of casing
(ft bTOC). Figure 3 depicts the groundwater elevations based off a benchmark of 100.00 ft given
to an arbitrary area near the southwest corner of the site. As depicted on Figure 3, the general
direction of groundwater flow beneath the site is to the southwest, southeast, and northeast.

3.2 Groundwater Sampling

On June 13, 2023, MW-4 and MW-6 through MW-12 were sampled. It should be noted that MW-
3 was found to be filled with sand to a depth of approximately 10 ft bTOC and thus groundwater
was not available for sampling.

Groundwater samples were collected using dedicated and disposable polyvinyl chloride (PVC)
bailers (1.5” x 3’) attached to braided nylon rope. Prior to groundwater sample collection, each
well was purged using the bailer. During purging, water quality parameters including pH,
conductivity, temperature, and turbidity were measured using calibrated field water quality
instruments. Readings were taken at the start of purging and periodically until a minimum of three
well volumes were removed from the well and water quality parameters stabilized. Following
Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

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purging, a groundwater sample for laboratory analysis was collected from the well using the bailer.
The water quality parameters were recorded on groundwater sampling forms along with time,
water level depth, and cumulative volume of water purged (see groundwater sampling forms in
Appendix B).

Groundwater samples were collected following Guidelines for Sampling by the Underground
Storage Tank Section, Division of Waste Management, North Carolina Department of
Environmental Quality (NCDEQ, 2022). Groundwater samples were placed in laboratory-
prepared vials preserved with hydrochloric acid (HCl), labeled, and stored on ice in a cooler for
subsequent delivery under standard chain-of-custody (COC) procedures to Pace Analytical (Pace),
a North Carolina-certified laboratory, located in Huntersville, North Carolina, for analysis. The
groundwater samples were analyzed for VOCs by EPA Method 6200B including MTBE, ethylene
dibromide (EDB), and isopropyl ether (IPE).

3.3 Free Product Evaluation

ESP originally planned to gauge free product thickness in MW-1 and determine if an additional
AVFR event would be warranted; however, the monitoring well was discovered buried under sand
and soil, with the well casing full of soil. Therefore, gauging of free product thickness or depth
to groundwater in this well was not possible.

3.4 Field Quality Control Sampling and Analysis

A field duplicate groundwater sample was collected on June 13, 2023 from MW-12 and analyzed
for VOCs by EPA Method 6200B including MTBE, EDB, and IPE to assess variance between
collected samples.

Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

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4.0 ANALYTICAL RESULTS

Results of the laboratory analysis of groundwater samples MW-4 and MW-6 through MW-12, plus
field duplicate, are tabulated in Table 3. As noted in Table 3, the analytical results are compared
to both 2L standards and GCLs. The Pace laboratory analytical report is provided in Appendix
C.

No analytes were detected at concentrations exceeding their respective GCLs; however, various
analytes were detected at concentrations greater than their respective 2L groundwater standards in
MW-4, MW-6, MW-8, MW-9, and MW-12. No analytes were detected above 2L standards in
MW-7, MW-10, or MW-11 (see Table 3 and Figures 4 and 5). A summary of the analytical
results is as follows:
• In MW-4, benzene (905 µg/L), diisopropyl ether (77.9 µg/L), MTBE (534 µg/L),
naphthalene (222 µg/L), and n-propylbenzene (105 µg/L) were detected above their
respective 2L standards;
• In MW-6, benzene (924 µg/L), diisopropyl ether (159 µg/L), MTBE (158 µg/L),
naphthalene (338 µg/L) and n-propylbenzene (77.4 µg/L) were detected above their
respective 2L standards;
• In MW-8, benzene (114 µ/L), MTBE (58.5 µg/L), and naphthalene (18.9 µg/L) were
detected above their respective 2L standards;
• In MW-9, benzene (2,960 µg/L), diisopropyl ether (79.9 µg/L), ethylbenzene (1,010 µg/L),
isopropylbenzene (99.7 µg/L), MTBE (296 µg/L), naphthalene (594 µg/L), n-
propylbenzene (191 µg/L), 1,2,4-trimethylbenzene (799 µg/L), and m&p-xylenes (2,790
µg/L) were detected above their 2L standards;
• In MW-12, benzene (348 µg/L), naphthalene (299 µg/L), and n-propylbenzene (166 µg/L)
were detected above their respective 2L Standards;
• In Duplicate (MW-12), benzene (409 µg/L), isopropylbenzene (73.9 µg/L), naphthalene
(358 µg/L), n-propylbenzene (193 µg/L), and 1,2,4-trimethylbenzene (492 µg/L) were
detected above their respective 2L Standards; and
• MW-7, MW-10, and MW-11 did not have any constituent concentrations greater than their
2L standards.

A comparison of groundwater laboratory analytical results from the June 13, 2023, sampling event
to the September 30, 2021, sampling event reveals that concentrations in site monitoring wells
have remained relatively stable except for MW-12, which has shown a continued downward trend
in concentrations. No exceedances of GCLs have been reported since the January 16, 2018
sampling event.

Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

9

5.0 CONCLUSIONS AND RECOMMENDATIONS

Based on results of the above field activities and previous reporting, ESP concludes the following:
• MW-1 and MW-3 were found to be filled with sand; thus, neither water level measurements
or collection of groundwater samples were possible;
• Static water level depths ranged from 2.60 ft to 9.11 ft bTOC;
• Free product was not encountered in any of the gauged monitoring wells;
• The general direction of groundwater flow beneath the site is to the southwest, southeast,
and northeast;
• No analytes were detected at concentrations exceeding their respective GCLs;
• Various analytes were detected at concentrations greater than their respective 2L
groundwater standards in MW-4, MW-6, MW-8, MW-9, and MW-12;
• No analytes were detected above 2L standards in MW-7, MW-10, or MW-11;
• A comparison of groundwater laboratory analytical results from the June 13, 2023,
sampling event to the September 30, 2021, sampling event reveals that concentrations in
site monitoring wells have remained relatively stable except for MW-12, which has shown
a continued downward trend in concentrations;
• No exceedances of GCLs have been reported since the January 16, 2018 sampling event;
and
• Due to our inability to gauge for free product in MW-1, the impact of the June 28, 2022
AFVR event at MW-1 could not be assessed.

Based on the above results, ESP offers the following recommendations:
• Continue to sample site monitoring wells on a semiannual basis to further understand
concentration trends and plume stability;
• Consider installation of replacement wells for MW-1, MW-3, and MW-5;
• Abandon compromised monitoring wells MW-1 and MW-3;
• Consider conducting an AFVR event on the MW-1 replacement well and possibly MW-9
to recover any remaining free product and further reduce constituent concentrations; and
• Install oxidation sleeves in monitoring wells MW-4, MW-6, MW-9, and MW-12 to attempt
to further reduce VOC concentrations and stabilize the contaminant plume.

Subsequent Monitoring Report ESP Project No. 23-00200-019
Ward’s Citgo (Incident #17850) August 24, 2023

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6.0 REFERENCES

Bladen County GIS, https://gis.bladenco.org/

1985 Geologic Map of North Carolina, The North Carolina Geological Survey, Phillip M. Brown,
1985.

Guideline for Sampling Underground Storage Tank Section, Division of Waste Management,
North Carolina Division of Environmental Quality, March 7, 2022, Change 4.

Terracon, November 2, 2021, Annual Monitoring Report: Ward’s Citgo (Incident #17850),
Clarkton, Bladen County, North Carolina.

Terracon, August 2, 2022, Aggressive Fluid Vapor Recovery Event Letter Report: Ward’s Citgo
(Incident #17850), Clarkton, Bladen County, North Carolina.

FIGURES

0 350 700Feet
ESP Associates, Inc.
P.O. Box 7030Charlotte, NC 28241
Phone [phone]
www.espassociates.com
SHEET TITLE
PROJECT
PROJECT NO.
SCALE
DRAWN BY
CHECKED BY
23-00200-019
ET
CWDATE08/01/2023
FIGURE 1USGS TOPOGRAPHIC SITE LOCATION MAPµAs Shown
CLARKTON, NORTH CAROLINA
SITE BOUNDARY
All locations are approximate.
WARD'S CITGO SITE
LEGEND:
<
<
<
<<
<
<
<
<
<
<
<
<
MW-2R
MW-3
MW-7
MW-8MW-4
MW-12 MW-5
MW-1
MW-18
MW-9
MW-11
MW-10
MW-6
PIT A
PIT B
PIT C
N W R LATHAM STREETGREEN STREET
0 20 40Feet
ESP Associates, Inc.
P.O. Box 7030Charlotte, NC 28241
Phone [phone]
www.espassociates.com
SHEET TITLE
PROJECT
PROJECT NO.
SCALE
DRAWN BY
CHECKED BY
23-00200-019
ET
CWDATE08/01/2023
FIGURE 2SITE MAPµAs Shown
CLARKTON, NORTH CAROLINA
SITE BOUNDARYMONITORING WELL (ACTIVE)MONITORING WELL (NOT LOCATED/ABANDONED)UST PITFORMER FUEL DISPENSERS
All locations are approximate.
WARD'S CITGO SITE
LEGEND:
<
<
<
<
<
<<
<
<
<
<
<
<
<
<
MW-2R
MW-3
MW-7
MW-8MW-4
MW-12 MW-5
MW-1
MW-18
MW-9
MW-11
MW-10
MW-6
PIT A
PIT B
PIT C
GREEN STREET N W R LATHAM STREET0 20 40Feet
ESP Associates, Inc.
P.O. Box 7030Charlotte, NC 28241
Phone [phone]
www.espassociates.com
SHEET TITLE
PROJECT
PROJECT NO.
SCALE
DRAWN BY
CHECKED BY
23-00200-019
ET
CWDATE08/01/2023
FIGURE 3GROUNDWATER ELEVATION MAPJUNE 13, 2023µAs Shown
CLARKTON, NORTH CAROLINA
SITE BOUNDARYMONITORING WELL (ACTIVE)MONITORING WELL (NOT LOCATED/ABANDONED)UST PITFORMER FUEL DISPENSERSESTIMATED GROUNDWATER FLOW DIRECTIONESTIMATED GROUNDWATER ELEVATION
All locations are approximate.
WARD'S CITGO SITE
LEGEND:
<
<
<
<
<
<<
<
<
<
<
<
<
<
<
MW-2R
MW-3
MW-7
MW-8MW-4
MW-12 MW-5
MW-1
MW-18
MW-9
MW-11
MW-10
MW-6
PIT A
PIT B
PIT C
GREEN STREET N W R LATHAM STREET0 20 40Feet
ESP Associates, Inc.
P.O. Box 7030Charlotte, NC 28241
Phone [phone]
www.espassociates.com
SHEET TITLE
PROJECT
PROJECT NO.
SCALE
DRAWN BY
CHECKED BY
23-00200-019
ET
CWDATE08/01/2023
FIGURE 4GROUNDWATER RESULTS MAPJUNE 13, 2023µAs Shown
CLARKTON, NORTH CAROLINA
SITE BOUNDARYMONITORING WELL (ACTIVE)MONITORING WELL (NOT LOCATED/ABANDONED)UST PITFORMER FUEL DISPENSERS
All locations are approximate.
WARD'S CITGO SITE
LEGEND:
<
<
<
<
<
<<
<
<
<
<
<
<
<
<
MW-2R
MW-3
MW-7
MW-8MW-4
MW-12 MW-5
MW-1
MW-18
MW-9
MW-11
MW-10
MW-6
PIT A
PIT B
PIT C
GREEN STREET N W R LATHAM STREET0 20 40Feet
ESP Associates, Inc.
P.O. Box 7030Charlotte, NC 28241
Phone [phone]
www.espassociates.com
SHEET TITLE
PROJECT
PROJECT NO.
SCALE
DRAWN BY
CHECKED BY
23-00200-019
ET
CWDATE08/01/2023
FIGURE 5BENZENE ISOCONCENTRATION MAPJUNE 13, 2023µAs Shown
CLARKTON, NORTH CAROLINA
SITE BOUNDARYMONITORING WELL (ACTIVE)MONITORING WELL (NOT LOCATED/ABANDONED)UST PITFORMER FUEL DISPENSERSAPPROXIMATE CONCENTRATION CONTOUR
All locations are approximate.
WARD'S CITGO SITE
LEGEND:
<
<

TABLES

Table 1
Water Supply Well Information
Ward's Citgo
Clarkton, North Carolina
NCDEQ Incident No. 17850
Well No.Property Owner Mailing
Address
Property
Address
Distance from
Source Area
(ft)
Hydraulic
Relationship to
Source Area
Well
Status/Use
Municpal
Water Parcel No.
TOC WSW-1 Town of Clarkton
P.O. Box 307
Clarkton, NC
28433
81 N. Elm
Street ~1,100 feet east Downgradient Active -
Potable No 120606299472
TOC WSW-3 Town of Clarkton
P.O. Box 307
Clarkton, NC
28433
205 Peach
Street
~1,350 feet
southeast Downgradient Active -
Potable No 120605283171
Notes:
Information obtained from previous monitoring report.
Table 2
Monitoring Well Construction and Groundwater Elevation Data
Ward's Citgo
Clarkton, North Carolina
NCDEQ Incident No. 17850
Well ID Date Intalled Screened Interval
(ft BGS) a
Bottom of
Well
(ft BGS) a
Top of Casing
Elevation
(ft) a,b
Date Water
Level Measured
Depth to Water
from Top of
Casing
(ft bTOC)
Groundwater
Elevation
(ft)
Free Product
Thickness
(ft.)
11/14/2019 0.04
2/8/2021 3.25 95.66 0.85
9/30/2021 5.30 93.86 1.20
6/13/2023 NM**NM**NM**
11/14/2019 10.85 88.90 ---
2/8/2021 7.13 92.62 ---
9/30/2021 9.20 90.55 ---
6/13/2023 NM**NM**NM**
11/14/2019 9.61 89.48 ---
2/8/2021 6.07 93.02 ---
9/30/2021 7.90 91.19 ---
6/13/2023 8.39 90.70 ---
11/14/2019 8.38 90.65 ---
2/8/2021 5.27 93.76 ---
9/30/2021 6.90 92.13 ---
6/13/2023 7.40 91.63 ---
11/14/2019 9.92 89.48 ---
2/8/2021 6.41 92.99 ---
9/30/2021 8.30 91.10 ---
6/13/2023 9.11 90.29 ---
11/14/2019 5.67 93.42 ---
2/8/2021 3.20 95.89 ---
9/30/2021 3.90 95.19 ---
6/13/2023 4.93 94.16 ---
11/14/2019 8.03 90.63 ---
2/8/2021 4.79 93.87 ---
9/30/2021 6.23 92.43 ---
6/13/2023 6.28 92.40 ---
11/14/2019 7.98 88.98 ---
2/8/2021 4.00 92.96 ---
9/30/2021 6.50 90.46 ---
6/13/2023 7.46 89.50 ---
11/14/2019 9.21 88.29 ---
2/8/2021 5.03 92.47 ---
9/30/2021 7.45 90.05 ---
6/13/2023 8.52 88.98 ---
11/14/2019 3.35 96.45 ---
2/8/2021 0.50 99.30 ---
9/30/2021 1.65 98.15 ---
6/13/2023 2.60 97.20 ---

Notes:
a Top of casing elevations, screened intervals, and bottom of well measurements are from previous consultants' monitoring reports.
b Top of casing elevations are based off of an assumed benchmark elevation of an arbitrary point within the site.
-- - no measureable free product
BGS - below ground surface
ft - feet
ft bTOC - feet below TOC
FP - free product
TOC - top of casing
NM - not measured
*No historical records for the screened interval or install date of this well. Not available in previous reports or NCDEQ Laserfiche database.
** MW-3 was partially filled with sand to a depth of approximately 10 ft bTOC while MW-1 was filled with sand to ground surface.
14.30 98.29
Free Product
c Groundwater elevation adjusted for measurable free product by using the following calculation:
(TOC Elevation - Depth to water) + (FP thickness * 0.729), where 0.729 is the specific gravity for automotive gasoline.
MW-1
MW-3
MW-4
MW-6
MW-7
MW-8
MW-10
MW-11
MW-12
MW-9
Unknown*
15.00
14.70
Unknown*
1/21/2016
Unknown*
Unknown*
3.8-13.8
5.0-15.0
Unknown*
4/27/2010
4/28/2010
4/27/2010
Unknown*
4/28/2010
7/19/2011
7/19/2011
2.75-12.75
5.0-15.0
5.0-15.0
5.0-15.0
5.9-15.9
99.75
99.40
98.68
97.50
99.80
99.09
99.03
99.09
96.96
15.00
12.75
15.00
15.90
13.80
15.00
15.00
Table 3
Summary of Groundwater Analytical Results
Ward's Citgo
Clarkton, North Carolina
NCDEQ Incident No. 17850
(Page 1 of 2)
1 70 70 70 70 600 70 20 6 70 600 400 400 500 500 500
5,000 5,900 8,800 14,750 70,000 80,000 30,500 20,000 6,000 26,100 260,000 28,500 24,100 50,000 50,000 50,000
1/16/18 <0.50 <0.50 <0.50 <0.50 0.33 J <0.50 <0.50 58.8 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
11/14/19 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 17 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
9/30/21 0.43 J <0.50 <0.50 <0.50 3.5 <0.50 <0.50 66 0.60 0.41 J <0.50 0.46 HJ <0.50 0.56 NR NR
6/13/23
1/16/18 137 <0.50 <0.50 <0.50 18.0 12.5 3.2 236 9.8 6.5 1.6 9.4 <0.50 24.2 NR NR
11/14/19 1,360 <0.50 <0.50 <0.50 125 147 46.1 1,340 139 99.6 <0.50 129 32.3 346 NR NR
9/30/21 950 H 5.1 3.7 0.79 120 H 66.0 50.0 1,100 H 120 96.0 3.0 66.0 18.0 169 H NR NR
6/13/23 905 4.3 <2.0 <1.6 77.9 46.6 62.3 534 222 105 2.3J 36.2 11.9 NR 47.2 11.6
1/16/18 1,130 <5.0 <5.0 <5.0 226 136 26.7 283 216 51.8 15.9 188 <5.0 102 NR NR
11/14/19 978 10.4 10.4 <5.0 184 138 32.5 205 266 70.2 <5.0 247 36.0 164 NR NR
9/30/21 1,400 7.1 7.2 <5.0 130 230 30.0 220 300 62.0 <5.0 240 50.0 244 NR NR
6/13/23 924 16.2 <2.0 <1.6 159 148 42.3 158 338 77.4 4.8 276 37.2 NR 162 7.4
1/16/18 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 1.2 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
11/14/19 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 7.9 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
9/30/21 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 1.3 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
6/13/23 <0.34 <0.49 <0.40 <0.32 <0.31 <0.30 <0.33 7.3 <0.64 <0.34 <0.24 <0.50 <0.33 NR <0.71 <0.34
1/16/18 225 <0.50 <0.50 <0.50 13.2 20.0 10.7 44.0 27.4 16.1 5.8 74.5 19.1 22.9 NR NR
11/14/19 370 4.6 4.2 <0.50 54.1 6.5 18.3 105 6.0 33.8 3.2 <0.50 <0.50 <0.50 NR NR
9/30/21 460 H 7.2 H 4.7 HJ 1.1 18 H 11 H 28 H 34 H 9.0 H 56 H 14 H 8 H 2.3 12.1 H NR NR
6/13/23 114 <0.49 4.7 1.5 37.2 9.5 30.8 58.5 18.9 48.8 4.3 14.8 5.0 NR 4.8 0.91
1/16/18 5,070 <10 <10 <10 166 1,450 87.8 1,170 480 185 938 894 228 3,642 NR NR
11/14/19 3,110 <10 <10 <10 94.6 1,140 89.2 443 453 191 292 757 174 2,505 NR NR
9/30/21 2,300 H 4.1 J <5.0 <5.0 44 H 810 H 39 H 180 H 190 H 82 H 560 H 480 H 120 H 2,320 H NR NR
6/13/23 2,960 <12.2 <10.0 <8.1 79.9 1,010 99.7 296 594 191 500 799 189 NR 2,790 271
1/16/18 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 3.1 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
11/14/19 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 2.1 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
10/1/21 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 0.47J <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
6/13/23 <0.34 <0.49 <0.40 <0.32 <0.31 <0.30 <0.33 <0.42 <0.64 <0.34 <0.24 <0.50 <0.33 NR <0.71 <0.34Benzenen-Butylbenzenesec-Butylbenzenetert-ButylbenzeneGCL (µg/L)
Sample
ID
Collection
Date
MW-4
MW-6
MW-10
MW-3
2L Standard (µg/L)m&p-Xyleneo-XyleneDiisopropyl ether (IPE)MW-9
MW-8
MW-7 Toluene1,2,4-Trimethylbenzene1,3,5-TrimethylbenzeneNot Sampled - obstruction in well casing Xylene (Total)EthylbenzeneIsopropylbenzene (cumene)Methyl tert-butyl ethyl (MTBE)Naphthalenen-Propylbenzene
Table 3
Summary of Groundwater Analytical Results
Ward's Citgo
Clarkton, North Carolina
NCDEQ Incident No. 17850
(Page 2 of 2)
1 70 70 70 70 600 70 20 6 70 600 400 400 500 500 500
5,000 5,900 8,800 14,750 70,000 80,000 30,500 20,000 6,000 26,100 260,000 28,500 24,100 50,000 50,000 50,000Benzenen-Butylbenzenesec-Butylbenzenetert-ButylbenzeneGCL (µg/L)
Sample
ID
Collection
Date
MW-3
2L Standard (µg/L)m&p-Xyleneo-XyleneDiisopropyl ether (IPE)Toluene1,2,4-Trimethylbenzene1,3,5-TrimethylbenzeneXylene (Total)EthylbenzeneIsopropylbenzene (cumene)Methyl tert-butyl ethyl (MTBE)Naphthalenen-Propylbenzene1/16/18 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
11/14/19 <0.50 <0.50 0.52 <0.50 <0.50 <0.50 <0.50 1.1 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
10/1/21 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 NR NR
6/13/23 <0.34 <0.49 <0.40 <0.32 <0.31 0.34J <0.33 0.49J <0.64 <0.34 <0.24 <0.50 <0.33 NR <0.71 <0.34
1/16/18 7,170 <25 <25 <25 <25 2,620 118 65.8 581 <25 12,800 1,600 <25 9,820 NR NR
11/14/19 4,120 <25 <25 <25 <25 1,970 114 18.5 672 299 1,120 1,930 <25 4,760 NR NR
9/30/21 740 26 16 <25 <25 980 90 27 340 250 170 1,200 280 1,994 NR NR
6/13/23 348 27.5 <1.6 <1.3 <1.2 424 64.2 <1.7 299 166 41.6 397 81.5 NR 384 13.2
Notes:
Bold values indicate constituent concentrations were greater than the 2L Standard.
Yellow highlighted values indicate constituent concentrations were greater than the GCL.
Samples presented prior to the May 31, 2023 event were obtained from prevous consultants reports.
<## - less than the method detection limit
µg/L - micrograms per liter
2L Standard - North Carolina 02L standard for groundwater
GCL - Gross Contaminant Level
H - Sample analyzed out of holding time
J - Estimated concentration above the method detection limit and below the reporting limit.
NR - not reported
MW-11
MW-12
6/13/23 409 31.0 <2.0 <1.6Duplicate
(MW-12)<1.5 508 16467NR98.049249.3193358<2.173.9

APPENDICES

APPENDIX A

APPENDIX B

APPENDIX C

ESP Corporate Office
3475 Lakemont Boulevard
Fort Mill, SC 29708
803.802.2440

Mailing Address: P.O. Box 7030 Charlotte, NC 28241
800.960.7317 | www.espassociates.com

Concord
7144 Weddington Rd. NW
Suite 110
Concord, NC 28027
704.793.9855

Cornelius
20484 Chartwell Center Dr.
Suite D
Cornelius, NC 28031
704.649.2863

Raleigh
2200 Gateway Centre Blvd.
Suite 216
Morrisville, NC 27560
919.678.1070

Greensboro
7011 Albert Pick Rd
Suite E
Greensboro, NC 27409
336.334.7724

Wilmington
211 Racine Drive
Suite 101
Wilmington, NC 28403
910.313.6648

Charleston
2154 North Center Street
Suite E-503
North Charleston, SC 29406
843.714.2040

Nashville
500 Wilson Pike Circle
Suite 310
Brentwood, TN 37027
615.760.8300

Pittsburgh
One Williamsburg Place
Suite G-5, Box 13
Warrendale, PA 15086
724.462.6606
Bradenton
518 13th Street
West Bradenton, FL 34205
941.345.5451

Indianapolis
8673 Bash Street
Indianapolis, IN 46256
317.537.6979

Albuquerque
1203 West Ella Drive
Corrales, NM 87048
505.314.1322

Birmingham
291 Cahaba Valley Parkway North Suite A
Pelham, AL 35124
205.664.8498

Vickrey & Associates, LLC - An ESP Company

San Antonio
12970 Country Parkway
San Antonio TX 78216
210.349.3271

Austin
3600 West Parmer Lane
Suite 175
Austin, TX 78727
512.494.8014

McAllen
1216 East Jasmine Avenue
Suite C
McAllen, TX 78501
956.340.0045