22054 2100 S Tryon Work Plan - Additional Soil Gas Sampling 20181221

Mr. Bill Schmithorst December 21, 2018
Page 2
S:\AAA-Master Projects\Vision Brokerage- VBG\VBG-013 2100 S. Tryon Street\Brownfields\Work Plan\Work Plan - Additional Soil Gas Sampling - 2100 S. Tryon Street (BF #22054-18-060).docx
• Non-petroleum UST related chlorinated solvents, including tetrachloroethene (PCE) were
detected in groundwater samples collected on the subject Site at concentrations above the
NC 2L Groundwater Standard (2L Standard).

• Marathon/Petro-Express (formerly known as Conoco Store #33012, Circle K #2723935,
and Kayo Oil, 2200 S. Tryon Street) is a gas station/convenience store located adjacent,
southeast, and topographically upgradient of the subject Site. In September 1991, soil and
groundwater contamination was discovered during removal of gasoline USTs and
associated product lines.

In September 2018, H&H conducted Phase II ESA activities at the Site to further evaluate the
potential for the above-mentioned concerns to impact the Site. The results of soil gas sampling
activities indicate the following:

• Multiple petroleum-related volatile organic compounds (VOCs) were detected at
concentrations above the North Carolina Department of Environmental Quality (DEQ)
Division of Waste Management (DWM) Soil Gas Screening Levels (SGSLs). To further
evaluate the detected compounds, H&H input the concentrations of the compounds in each
sample into the DEQ Risk Calculator (February 2018 Version). Risk calculations indicate
that only soil gas concentrations in the northeastern portion of the Site exceed DEQ
acceptable risks under a non-residential use scenario.

• PCE was detected at a concentration above the Residential SGSL but below the Non-
Residential SGSL in one soil gas point sample (SG-1) collected in the northwestern portion
of the Site. However, the cumulative potential carcinogenic and non-carcinogenic risks in
the SG-1 sample are acceptable under both residential and non-residential use scenarios.

Based on email correspondence dated December 5, 2018, we understand that the DEQ Brownfields
Program recently reviewed the 2018 Phase I and II ESA reports prepared by H&H to assess and
Mr. Bill Schmithorst December 21, 2018
Page 3
S:\AAA-Master Projects\Vision Brokerage- VBG\VBG-013 2100 S. Tryon Street\Brownfields\Work Plan\Work Plan - Additional Soil Gas Sampling - 2100 S. Tryon Street (BF #22054-18-060).docx
delineate soil, groundwater, and soil gas impacts at the Site. Based on DEQ Brownfields review
of the documents, we understand that DEQ has requested the following additional action items:

1) collection of two additional soil gas samples from locations in the northeastern portions of
the Site in an area of a former gas station for the purpose of worker protection during future
redevelopment activities; and
2) preparation and submittal of a Work Plan for DEQ approval prior to conducting soil gas
sampling.

A summary of our scope of work to conduct the additional DEQ requested activities is presented
in the following Section.

2.0 Phase II ESA Scope of Work
2.1 Utility Location

Prior to conducting soil gas sampling activities, H&H will contact North Carolina 811, the public
utility locator, to mark subsurface utilities located on the Site. H&H will also hire a private utility
locator to screen proposed boring locations for subgrade utilities. Prior to boring advancement, a
hand auger will be advanced to a depth of approximately 5 ft below ground surface (ft bgs) at each
proposed boring location to further clear the boring of potential subsurface utilities.

2.2 Soil Gas Sampling

H&H collected soil gas samples from seven (7) locations at the Site (SG-1 through SG-7). As
requested by DEQ, H&H proposes to install and sample two (2) additional temporary subsurface
soil gas monitoring points (SG-8 and SG-9) at locations near W. Tremont Avenue and S. Tryon
Street to further evaluate soil vapor delineation data near the property lines in the northeastern
portion of the Site (see Figure 2).

Mr. Bill Schmithorst December 21, 2018
Page 4
S:\AAA-Master Projects\Vision Brokerage- VBG\VBG-013 2100 S. Tryon Street\Brownfields\Work Plan\Work Plan - Additional Soil Gas Sampling - 2100 S. Tryon Street (BF #22054-18-060).docx
The soil gas points will be installed and sampled in general accordance with the DEQ Division of
Waste Management (DWM) Vapor Intrusion Guidance dated March 2018 and as described below.
The soil gas monitoring points will be installed using hand auger and DPT methods to a depth
approximately 3-5 ft above the water table and at least 5 ft below grade. During recent Phase II
ESA activities, groundwater was identified at a depth of approximately 20 ft below the ground
surface (bgs) in the northeastern portion of the Site. Therefore, H&H anticipates installing soil
gas points SG-8 and SG-9 at a depth of approximately 15 ft bgs. During advancement of the
borehole, soil recovered from the DPT sampler or hand auger will be described for lithologic
purposes, and will be screened for the presence of odors, staining, and for organic vapors utilizing
a calibrated photo-ionization detector (PID).

The soil gas monitoring points will be constructed with a 6-inch long screen point fitted with
Teflon® tubing that extends to the surface. Once the screen point has been set at the desired depth,
sand will be installed in the boring around the screen point to approximately 6-inches above the
top of the screen. Following installation of the sand, hydrated bentonite will be installed from the
top of the sand to approximately 6-inches bgs. Following installation, H&H will purge
approximately three volumes of vapor from the screen point and Teflon® tubing using a dedicated
syringe provided by the laboratory. Following purging, the Teflon® tubing will be capped and the
soil gas monitoring point will be allowed to stabilize for a minimum of 24 hours.

A field leak check will be conducted at each soil gas monitoring point sample location. The leak
check will be conducted by placing a temporary shroud around the above ground portion of the
sampling point and saturating the air within the shroud with helium gas. The concentration of
helium gas in the shroud will be measured using a helium gas detector, with the goal being
approximately 75% to 100% helium. Vapor will be purged from the soil gas point using a
dedicated syringe provided by the laboratory and sampled outside of the shroud into a separate
Tedlar® bag and analyzed using the helium gas detector to ensure that helium concentrations from
the soil gas monitoring point are less than 10% of the helium concentrations in the shroud. Shut-
in leak tests will be performed on each Summa canister and sampling train prior to sampling.

Mr. Bill Schmithorst December 21, 2018
Page 5
S:\AAA-Master Projects\Vision Brokerage- VBG\VBG-013 2100 S. Tryon Street\Brownfields\Work Plan\Work Plan - Additional Soil Gas Sampling - 2100 S. Tryon Street (BF #22054-18-060).docx
Following a successful leak check, soil gas samples will be collected into 6-liter stainless steel
Summa canisters for laboratory analysis. The Summa canisters will be allowed to fill slowly using
an airflow regulator over a period of approximately one hour at each location. During collection
of the samples, H&H will collect measurements of ambient temperature at the beginning, middle,
and end of the sampling day. Precipitation, if any, will also be noted.
Vacuum readings during sample collection will be recorded in a field book at approximate 15
minute-intervals during the sampling event. The vacuum pressure in each Summa
canister upon completion of the sampling event will be between three and six inches of mercury.
Following sample collection, the Summa canisters will be shipped to Pace Analytical
Laboratories, Inc. (Pace) of Huntersville, NC for analysis of VOCs by EPA Method TO-15.
Upon receipt of the canisters, H&H will request that the laboratory measure and record the
vacuum in each canister.
For quality control purposes, one duplicate soil gas sample (DUP-1) will be collected for
laboratory analysis of VOCs by EPA Method TO-15. The soil gas point locations will be
estimated using a sub-meter GPS unit.
2.3 Investigation Derived Waste
Based on previous soil data, we anticipate soil cuttings generated from this investigation will be
spread on-Site in accordance with 15A NCAC 02T.1503. However, if significant impacts are
suspected, the soil cuttings will be containerized in 55-gallon drums, and a composite sample of
the waste soil will be submitted for laboratory analysis.
3.0 Phase II ESA Reporting
Following completion of the soil gas sampling activities and receipt of the analytical data, H&H
will document our findings in an updated Phase II ESA Report. The report will include a
description of the sampling activities, a figure depicting sample locations, boring logs, a discussion
of the data in comparison to regulatory screening levels, results of risk calculations, laboratory
analytical data, and conclusions concerning our activities. H&H will request that the laboratory
Mr. Bill Schmithorst December 21, 2018
Page 6
S:\AAA-Master Projects\Vision Brokerage- VBG\VBG-013 2100 S. Tryon Street\Brownfields\Work Plan\Work Plan - Additional Soil Gas Sampling - 2100 S. Tryon Street (BF #22054-18-060).docx
meet reporting and method detection limits and report estimated “J-flag” values in the lab data.
The report will include a firm PE/PG license number and will be sealed by a PE/PG prior to
submittal to DEQ.
We look forward to your approval of this work plan. If you have any questions or comments
concerning this submittal, please contact us.
Very truly yours,
Hart & Hickman, PC
Matt Ingalls Brett Lawrence, PG
Project Manager Project Geologist
Attachments:
Table 1 Proposed Sample Location and Summary Table
Figure1
Figure 2
Site Location Map
Proposed Sample Location Map
Appendix A Summary of Historical Soil Gas Data

Table 1 Proposed Sample Location and Summary Table
2100 S. Tryon Street Brownfields Site
Charlotte, North Carolina
DEQ Brownfields Project #22054-18-060 H&H Job No. VBG-013

Sample ID Sample Objective Proposed Depth (ft bgs)
Analytical Method
SG-8 Assess soil vapor in the NE portion of the Site along Tremont Avenue 15 VOCs by TO-15
SG-9 Assess soil vapor in the NE portion of the Site along
S. Tryon Street 15 VOCs
by TO-15
DUP-1 QA/QC 15 VOCs by
TO-15
Note:
VOCs = volatile organic compounds ft bgs = feet below the ground surface
QA/QC = quality assurance/quality control
TITLE
PROJECT
SITE LOCATION MAP
2100 S. TRYON STREETCHARLOTTE, MECKELENBURG COUNTY
NORTH CAROLINA
DATE:
JOB NO:
REVISION NO:
FIGURE:
6/15/2018 0
1VBG-013
SITE
0 2000 4000
APPROXIMATE
SCALE IN FEET
N
U.S.G.S. QUADRANGLE MAP
QUADRANGLE
7.5 MINUTE SERIES (TOPOGRAPHIC)
CHARLOTTE EAST, NORTH CAROLINA 1991
GAS FIRED PRODUCTS
(421 WEST TREMONT AVENUE)SOUTH TRYON STREETWEST TREM
O
N
T

A
V
E
N
U
E
CAROLINA CORE RECYCLING
(511-567 WEST TREMONT AVENUE)
INNER PEAKS CLIMBING
(FORMER DIXIE ELECTRONICS)
(2220 SOUTH TRYON STREET)
MARATHON/PETRO
EXPRESS GAS STATION
K9 PLAYLAND
(2139 SOUTH TRYON STREET)
KEG'N'QUE
(2135 SOUTH TRYON STREET)
BEST IN TECH
(2123 SOUTH TRYON STREET)
NEONWORKS
(2115 SOUTH TRYON STREET)
ENVIRONMENT SERVICES
OF CHARLOTTE
(2107 SOUTH TRYON STREET)
FORMER VCC
FORMER TREMONT MUSIC HALL
(400 WEST TREMONT AVENUE)
SOUTH TRYON COMMERCIAL
(2025 SOUTH TRYON STREET)
PRETTY-N-INK
(2030 SOUTH TRYON STREET)
NORTHERN
PARCEL
SOUTHERN
PARCEL
SIGNS DESIGNED
(2119 SOUTH TRYON STREET)
HIBISCUS
(2125 SOUTH TRYON STREET)
MICHEAL GAVON SALON AND
TRANSFORMATIONS
INTERIORS
(2131 SOUTH TRYON STREET)
BILLBOARD
FORMER UST BASIN
FORMER SUNOCO
GAS STATION
FORMER PUMP
ISLAND
GRAVEL PARKING
AREA
UST BASIN
FORMER RAIL SPUR
LOCATION
PROPOSED PARKING
DECK
PROPOSED OFFICE
BLDG
PROPOSED OFFICE
BLDG
SB-4
TMW-1
SG-1
SG-4
SG-2
SG-3
SG-7
SB-2
SB-3
SB-5
SB-6
SB-7
TMW-2
TMW-3
TMW-4
SB-1
SG-5
SG-6
REVISION NO. 0
JOB NO. VBG-013
DATE: 9-18-18
FIGURE NO. 4
VACANT PROPERTY
2100 S. TRYON STREET
CHARLOTTE, NORTH CAROLINA
PROPOSED SOIL GAS SAMPLE
LOCATION MAP
LEGEND
SITE PROPERTY BOUNDARY
PROPOSED STRUCTURE
POLE-MOUNTED TRANSFORMER
SOIL BORING LOCATION
SOIL GAS POINT LOCATION
TEMPORARY MONITORING WELL
LOCATION
ESTIMATED EXTENT OF SOIL GAS
IMPACTS ABOVE NON-RESIDENTIAL
SCREENING LEVELS
ESTIMATED EXTENT OF SOIL GAS
IMPACTS ABOVE RESIDENTIAL
SCREENING LEVELS
2923 South Tryon Street-Suite 100
Charlotte, North Carolina 28203
704-586-0007(p) 704-586-0373(f)
License # C-1269 / #C-245 Geology
NOTE:
ANALYTICAL RESULTS FOR SG-1 INDICATED LOW LEVEL
DETECTIONS OF PCE BUT WAS EXCLUDED FROM IMPACTED
SOIL GAS AREA BECAUSE RISK CALCULATIONS INDICATED
AN ACCEPTABLE RISK IN THIS SAMPLE.S:\AAA-Master Projects\Vision Brokerage- VBG\VBG-013 2100 S. Tryon Street\Phase II ESA\Figures\Site Plan-Phase II.dwg, FIG 4, 9/18/2018 10:51:09 AM, erichardson
Appendix A
Summary of Historical Soil Gas Data
Table 3Summary of Soil Gas Analytical Data2100 S Tryon StreetCharlotte, North CarolinaH&H Job No. VBG-013Sample ID SG-1 SG-2 SG-3SG-DUP (SG-3)SG-4 SG-5 SG-6 SG-7Sample Date 8/22/2018 8/22/2018 8/22/2018 8/22/2018 8/22/2018 8/22/2018 8/22/2018 8/22/2018Screen Depth (ft bgs) 7.5-8 12.5-13 12.5-13 12.5-13 8.5-9 8.5-9 7.5-8 4.5-5Units µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ µg/m³Location DescriptionCentral Portion of the SiteFormer Rail SpurSouthern Portion of the SiteVOCs (TO-15)Acetone 9.4<10,60011.2 15.1 35.0 J 10.6 4.2 360 220,000 2,700,000Benzene 7.386,6005.8 4.3 70.0 108 0.87 31.7 120 1,600Bromomethane<0.39 <1,990 <0.35 <0.36 <4.0 <0.36 <0.370.39 J 35 4402-Butanone (MEK)<0.63 <3,230 <0.57 <0.58 <6.5 <0.58 <0.5957.5 35,000 440,000Carbon disulfide 56.4<1,92023.0 25.1 195 494 3.2 20.9 4,900 61,000Carbon tetrachloride<0.73 <3,760 <0.66 <0.68 <7.5 <0.68 <0.691.2 J 160 2,000Chloroform 6.5<1,72014.8 14.5<3.4 <0.310.45 J 0.70 J 41 530Chloromethane<0.27 <1,370 <0.240.34 J<7.4 <0.250.40 J 0.76 630 7,900Cyclohexane 20.3<3,090 <0.55 <0.56 <6.254.9 0.83 J 1.7 J 42,000 530,0001, 4-Dichlorobenzene<1.7 <8,760 <1.6 <1.6 <17.5 <1.6 <1.65.6 85 1,100Dichlorodifluoromethane 2.3<2,5701.8 2.0<5.12.1 1.8 2.7 700 8,800Ethyl acetate 1.5<1,660 <0.29 <0.30 <3.3 <0.30 <0.313.6 2,700 11,000Ethylbenzene 37.6318,00030.1 24.9394 5118.7 4.3 370 4,9004-Ethyltoluene 12.4 98,600 8.4 6.8 123 159 2.9 J 3.5 J NE NEn-Heptane 28.4537,00021.1 12.1 127 143<0.615.0 2,800 35,000n-Hexane 26.6486,00013.7 5.1 66.9 52.6 1.1 J 7.9 4,900 61,000Methylene Chloride 13.5<8,2604.6 J 4.8 J<16.53.9 J 5.6 J 4.3 J 4,200 53,0004-Methyl-2-pentanone (MIBK)<0.89 <4,540 <0.80 <0.82 <9.1 <0.82 <0.831.1 J 21,000 260,000Naphthalene 3.8 J20,100 J3.4 J 3.4 J40.6 J3.9 J 3.3 J 4.8 21 260Propylene 71.9<1,2502.6 3.3<2.570.7 1.7<0.2478 330Styrene<0.59 <3,010 <0.53 <0.54 <6.0 <0.54 <0.55 <0.597,000 88,000Tetrachloroethene (PCE)443<2,7502.4 3.4 185 1.8<0.511.4 280 3,500Tetrahydrofuran<0.45 <2,290 <0.40 <0.41 <4.6 <0.41 <0.9718.5 14,000 180,000Toluene 143 9,070 98.6 101 1,510 2,260 23.7 21.3 35,000 440,000Trichloroethene<0.44 <2,250 <0.40 <0.41 <4.5 <0.41 <0.41 <0.4414 180Trichlorofluoromethane 18.1<3,2001.1 J 0.99 J<6.41.6 J 1.0 J 2.3 NS NS1,2,4- Trimethylbenzene 19.3224,00018.1 14.1 287 375 6.3 14.0 420 5,3001,3,5- Trimethylbenzene 6.8134,0006.0 4.4 78.8 109 2.4 3.7 420 5,300m&p- Xylenes 106314,00088.0 84.61,250 1,79028.3 20.0 700 8,800o- Xylene 40.44,000 J25.2 25.8 410 588 10.3 7.0 700 8,800Notes:1) North Carolina Department of Environmental Quality (DEQ) Division of Waste Management (DWM) Residential Soil Gas Screening Levels (SGSLs), February 20182) North Carolina DEQ DWM Non-Residential SGSLs, February 2018EPA Method number follows parameter in parenthesisBold concentration exceeds North Carolina DEQ DWM Residential SGSLsBold and Underlined concentration exceeds North Carolina DEQ DWM Residential and Non-Residential SGSLsft bgs = feet below ground surface; NE = not establishedµg/m³ = micrograms per cubic meterOnly those compounds detected in at least one sample shown above, with the exception of trichloroetheneJ = result is less than the laboratory reporting limit but greater than or equal to the method detection limit. The concentration is a lab calculated approximate valueScreening Criteria Non-Residential Soil Gas Screening Level2Residential Soil Gas Screening Level1Former Sunoco Gas StationS:\AAA-Master Projects\Vision Brokerage- VBG\VBG-013 2100 S. Tryon Street\Brownfields\EMP\Tables\Data Tables for EMP11/5/2018Table 3Hart & Hickman, PC