19054_HD Supply WP_Approval Sampling 20220420

April 20, 2022
Sent Via E-mail Bo Cappleman
Hart & Hickman, PC
2923 S Tryon Street, Suite 100 Charlotte, NC 28203 [e-mail]
Subject: Supplemental Post-Occupancy VIMS Efficacy Sampling Work Plan-Approval HD Supply Brownfields Property Charlotte, Mecklenburg County Brownfields Project No. 19054-15-060

Dear Mr. Cappleman: The North Carolina Department of Environmental Quality (DEQ) Brownfields Program received the Supplemental Post-Occupancy VIMS Efficacy Sampling Work Plan dated April 18, 2022 (Work Plan).
DEQ Brownfields comments to previous revision dated April 11, 2022 of this Work Plan have been
addressed; therefore, the Work Plan is approved. Please be advised that this approval from DEQ Brownfields does not waive any applicable requirement to obtain any necessary permits, licenses or certifications which may be required from other state or local
entities. If you have any questions, please feel free to contact me at 704-661-0330, or via e-mail at
[e-mail]. Sincerely,

Carolyn Minnich Brownfields Project Manager
ec: Andrew Besu [e-mail]
DuBose Williamson [e-mail]

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- Centro Railyard (4-11-22_rev 4-18-22).doc
Supplemental Post-Occupancy VIMS Efficacy Sampling Work Plan
Centro Railyard
HD Supply Brownfields Site
1425 Winnifred Street
Charlotte, North Carolina
Brownfields Project No. 19054-15-060
H&H Job No. CTT-001

Table of Contents

Section Page No.

1.0 Introduction ............................................................................................................................ 1 
2.0 Scope of Work ........................................................................................................................ 3 
2.1 Indoor Air Sampling ............................................................................................................. 3 
2.2 Sub-Slab Vapor Assessment ................................................................................................. 4 
2.3 Quality Assurance/Quality Control ...................................................................................... 5 
3.0 Reporting ................................................................................................................................ 7 

List of Tables
Table 1 Sample Summary Table
Table 2 Site-Specific VOC List
List of Figures
Figure 1 Site Location Map
Figure 2 Site Map
Figure 3 Proposed Sub-Slab Vapor and Indoor Air Sample Location Map

List of Appendices

Appendix A Level 1 and Level 2 Floor Plans

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Supplemental Post-Occupancy VIMS Efficacy Sampling Work Plan
Centro Railyard
HD Supply Brownfields Site
1425 Winnifred Street
Charlotte, North Carolina
Brownfields Project No. 19054-15-060
H&H Job No. CTT-001

1.0 Introduction

As requested by the Brownfields Program, Hart & Hickman, PC (H&H) is pleased to present this
work plan to conduct supplemental post-occupancy vapor intrusion mitigation system (VIMS)
efficacy indoor air and sub-slab vapor sampling for the Centro Railyard apartments located at
1425 Winnifred Street in Charlotte, Mecklenburg County, North Carolina (Site). The Site is
located in the western portion of the HD Supply Brownfields Property and is subject to the North
Carolina Department of Environmental Quality (DEQ) Notice of Brownfields Property
(Brownfields Project No. 19054-15-060). A Site location map is provided as Figure 1, and a Site
map showing the HD Supply Brownfields Property is included as Figure 2.

As part of the Site development, the Brownfields Program required the installation of a VIMS in
the southern wing of the Centro Railyard apartment building as outlined in the DEQ-approved
Vapor Mitigation Plan – Revision 1 (VMP) dated May 30, 2019 prepared by H&H. A passive
VIMS is currently installed within the Centro Railyard apartment building in accordance with the
VMP. The sub-slab components of the VIMS consists of 3-inch slotted PVC horizontal vapor
collection piping installed within a 4-inch to 5-inch thick layer of 57 stone overlain by the Stego
Industries, LLC 20-mil Drago Wrap vapor barrier. The sub-slab vapors collected by the sub-slab
piping are then conveyed above the roofline by 3-inch risers terminated with wind-driven passive
ventilator fans. The building includes a slab-on-grade foundation with retail and amenity spaces
on the ground level and residential and amenity spaces on the upper floors.

In accordance with the DEQ-approved VMP and installation reports, H&H completed annual
post-occupancy indoor air sampling event in April 2021. In addition, H&H completed a separate
indoor air sampling event following tenant upfit activities in Commercial Space 12 in

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April 2021, and a supplemental sub-slab vapor and indoor air sampling event was conducted
approximately five months after the tenant upfit in August 2021. The results of indoor air
sampling were summarized and submitted to DEQ in the VIMS Post-Occupancy Annual indoor
Air Sampling Report dated May 14, 2021 and the VIMS Upfit Inspection and Sampling Report –
Revision 1 dated November 29, 2021. Based on the results of indoor air sampling in 2021, DEQ
requested collection of two additional indoor air samples and a sub-slab vapor sample adjacent to
the elevator doors to assess potential VOC migration from floor 1 to floor 2 via the elevator
shaft. The methodology for proposed sub-slab vapor and indoor air sampling is provided below.

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2.0 Scope of Work

The supplemental vapor intrusion assessment activities will be performed in conjunction with the
annual post-occupancy indoor air sampling activities and in general accordance with DEQ’s
Inactive Hazardous Sites Branch (IHSB) Guidelines for Assessment and Cleanup (Guidelines)
dated July 2021, the DEQ Division of Waste Management (DWM) Vapor Intrusion Guidance
dated March 2018, and most recent version of the U.S. Environmental Protection Agency (EPA)
Region IV Laboratory Services and Applied Science Division (LSASD) guidance. A sample
summary table is provided as Table 1, the proposed sample locations are depicted on Figure 3,
and building floor plans for Level 1 and Level 2 are provided as Appendix A. The proposed
scope of work is presented in the following sections.

2.1 Indoor Air Sampling

Prior to collecting indoor air samples, H&H will complete an Indoor Air Building Survey and
Sampling Form to document conditions within the sampling areas and to identify potential
background sources of volatile organic compounds (VOCs). The results of the survey will be
incorporated into the laboratory data evaluation.

DEQ has requested collection of one indoor air sample adjacent to elevator doors on floor 1
(adjacent to retail space) and floor 2 (within non-residential common areas), for a total of two
indoor air samples. A duplicate indoor air sample will be collected from the sample location on
floor 2. An indoor air sample adjacent to the elevator door on floor 1 is required for annual
indoor air sampling activities. Therefore, the supplemental vapor intrusion assessment activities
will satisfy a portion of the annual indoor air sampling activities. In addition, a background
ambient air sample will be collected at a location upwind of the Site. The indoor air samples will
be collected using individually-certified Summa canisters, and the background sample will be
collected using a batch-certified Summa canister. The Summa canisters will be connected to a
laboratory-provided in-line flow controller set to collect the sample over a 24-hour period.

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Following sample collection, the Summa® canisters will be placed in laboratory-supplied
shipping containers, properly labeled, and shipped under standard chain-of-custody protocols to
a qualified laboratory for analysis of select VOCs by EPA Method TO-15 in accordance with the
VMP. Site-specific VOCs, which include all VOCs that have historically been detected during
previous soil gas sampling at the Site, are listed in Table 2. The laboratory will be requested to
use reporting limits that are below DEQ DWM Residential and Non-Residential Indoor Air
Screening Levels (IASLs).

2.2 Sub-Slab Vapor Assessment

H&H will collect one sub-slab vapor sample and a duplicate sample from monitoring point
OP-2. The sub-slab vapor sample will be collected utilizing laboratory-supplied batch certified
Summa® canisters (1 or 3-Liter canisters depending on laboratory availability) connected to an
air-flow regulator calibrated by the laboratory to collect the sub-slab vapor at a rate no greater
than 200 mL/min. Prior to collection of the sub-slab vapor samples, a “shut-in” test will be
conducted on the sampling train and a helium leak check will be conducted at the sub-slab vapor
sampling point. The purpose of the shut-in test and helium leak check is to ensure that short
circuiting with ambient air does not occur during sampling. A description of the shut-in test and
helium leak testing procedures is provided below.

The shut-in test will be conducted by connecting the flow regulator with the vacuum gauge to the
Summa® canister and sealing the flow regulator with the laboratory provided brass cap. Once
the sampling train is “closed”, the sample valve on the Summa® canister will be opened and the
reading on the vacuum gauge will be recorded. The Summa® canister sample valve will then be
closed and the vacuum gauge will be observed to ensure no vacuum loss occurs. If the vacuum
reading remains the same, the shut-in test will be considered successful. If vacuum loss occurs,
the flow regulator and/or brass cap will be reseated and the shut-in test will be repeated until the
vacuum reading remains stable.

Following the shut-in test, the Summa® canister will be connected to the sample point via
Teflon® sample tubing using a brass nut and ferrule assembly to create an airtight seal and the

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leak check will be performed. The leak check will be performed by constructing a shroud over
the sampling train, including the canister, and flooding the shroud with helium gas. A calibrated
helium gas detector will be utilized to measure helium concentrations within the shroud. Once
helium concentrations stabilize within the shroud, the sample tubing will be purged outside of
the shroud using a syringe and a three-way valve to collect purged soil gas into a Tedlar® bag.
The purged sub-slab vapor will then be analyzed using the helium gas detector to ensure that
helium concentrations in the soil gas point are less than 10% of the helium concentrations
measured within the shroud.

Following a successful leak check, the sub-slab vapor sample will be collected. Vacuum
readings on the Summa® canister will be recorded prior to and following the sampling period to
ensure adequate sample volume was collected. A vacuum will be maintained within the
canisters at the conclusion of the sampling event with a target of 5 inches of mercury remaining
in the summa canisters at the conclusion of sampling.

Following sample collection, the Summa® canisters will be placed in laboratory-supplied
shipping containers, properly labeled, and shipped under standard chain-of-custody protocols to
a qualified laboratory for analysis of select VOCs by EPA Method TO-15 (see Table 2). The
laboratory will be requested to use reporting limits that are below DEQ DWM Residential Sub-
Slab and Exterior Soil Gas Screening Levels (SGSLs).

2.3 Quality Assurance/Quality Control

For field and laboratory quality assurance/quality control (QA/QC) purposes, H&H will collect
one duplicate sub-slab vapor sample and one duplicate indoor air sample. The duplicate samples
will be analyzed for the same parameters as the parent samples.

Laboratory QA/QC procedures will be employed to ensure appropriate sample handling and
analysis and to aid in the review and validation of the analytical data. QA/QC procedures will be
conducted in accordance with the method protocols and will include regular equipment
maintenance, equipment calibrations, and adherence to specific sample custody and data

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management procedures. Samples will be analyzed in conjunction with appropriate blanks,
laboratory duplicates, continuing calibration standards, surrogate standards, and matrix spiking
standards in accordance with approved methodologies to monitor both instrument and analyst
performance. Laboratory reporting limits for each analyte will be at or below appropriate
screening criteria, where possible. Additionally, H&H will request that the laboratory include
estimated concentrations for compounds that are detected at levels above the laboratory method
detection limit, but below the laboratory reporting limit (J flags).

The laboratory analytical data report and QA package for each group of samples submitted to
and analyzed by the subcontracted laboratory will be provided in an appendix to the final report.
Laboratory QA data consistent with Level II documentation will be provided for this project. A
copy of the completed chain of custody record will be appended to the corresponding laboratory
analytical report included with the final report.

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3.0 Reporting

Following completion of assessment activities and receipt of the analytical data, H&H will
include the results of supplemental vapor intrusion assessment in the VIMS Post-Occupancy
Annual Indoor Air Sampling Report which describes the methods and results of the vapor
intrusion assessment activities conducted. The report will include a description of the sampling
activities, a figure depicting sample locations, laboratory analytical data, a discussion of the data
in comparison to regulatory screening levels, risk calculations, and conclusions and
recommendations concerning our activities.

Table 1Sample Summary TableCentro RailyardHD Supply Brownfields Site1425 Winnifred StreetCharlotte, North Carolina H&H Project No. CTT-001IAS-1 (Floor 1) Indoor Air 1IAS-2 (Floor 2) Indoor Air 1SSV-OP-2 Sub-Slab VaporAssess sub-slab vapor for comparison to indoor air sampling results1DUP-1 Indoor Air 1DUP-2 Sub-Slab Vapor 1BG-1 Ambient Air Background 1Notes:VOCs = Volatile Organic Compounds; QA/QC = Quality Assurance/Quality ControlAssess potential VOC migration from Floor 1 to Floor 2 via the elevator shaftQA/QCselect VOCs by EPA Method TO-15Sample IDsNumber of SamplesLaboratory AnalysisSample ObjectiveSample Typehttps://harthick.sharepoint.com/sites/MasterFiles-1/Shared Documents/AAA-Master Projects/Collett Capital - CTT/CTT-001 Centro Railyard/2022 Additional Post-Occupancy Sampling/Sample Summary Table 2.xlsxTable 1Hart & Hickman, PC
Table 2
Site-Specific VOC List
HD Supply Brownfields Property/Centro Railyard
1425 Winnifred Street
Charlotte, North Carolina
H&H Job No. CTT-001
Select VOCs by TO-15
Acetone
Benzene
1,3-Butadiene
2-Butanone
Carbon Disulfide
Carbon Tetrachloride
Chloroethane
Chloroform
Chloromethane
Cyclohexane
1,3-Dichlorobenzene
Dichlorodifluoromethane
1,2-Dichloropropane
Ethanol
Ethyl Acetate
Ethylbenzene
4-Ethyltoluene
Heptane
Hexane
Isopropanol
Methylene Chloride
4-Methyl-2-pentanone
Naphthalene
Propene
Styrene
Tetrachloroethene
Toluene
Trichloroethene
Trichlorofluoromethane
1,1,2-Trichloro-1,2,2-trifluoroethane
1,2,4-Trimethylbenzene
1,3,5-Trimethylbenzene
Vinyl Chloride
m&p-Xylene
o-Xylene
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5/5/2021
Table 2
Hart & Hickman, PC
Copyright:© 2013 National Geographic Society, i-cubed
SITE LOCATION MAP
CENTRO RAILYARD1425 WINNIFRED STREETCHARLOTTE, NORTH CAROLINA
DATE: 11-19-20
JOB NO: CTT.001
REVISION NO: 0
FIGURE NO: 1
2923 South Tryon Street - Suite 100Charlotte, North Carolina 28203704-586-0007 (p) 704-586-0373 (f)License # C-1269 / # C-245 Geology
TITLE
PROJECT
0 2,000 4,000
SCALE IN FEET
SITE
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U.S.G.S. QUADRANGLE MAP
CHARLOTTE EAST, NORTH CAROLINA 2013
QUADRANGLE7.5 MINUTE SERIES (TOPOGRAPHIC)
S. TRYON STREETW
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S
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B
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WINNIFRED STREETW
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NORTH
TOWER
PARKING
GARAGE
CENTRO RAILYARD APARTMENTS AND
GROUND LEVEL RETAIL
RAILYARD NORTH TOWER
RAILYARD SOUTH TOWER
REVISION NO. 0
JOB NO. CTT-001
DATE: 4-11-22
FIGURE NO. 2
HD SUPPLY BROWNFIELDS SITE
S. TRYON STREET AND WINNIFRED STREET
CHARLOTTE, NORTH CAROLINA
SITE MAP
LEGEND
CENTRO RAILYARD MIXED-USE DEVELOPMENT
THE RAILYARD COMMERCIAL DEVELOPMENT
2923 South Tryon Street-Suite 100
Charlotte, North Carolina 28203704-586-0007(p) 704-586-0373(f)License # C-1269 / #C-245 Geology
NOTES:
1. AERIAL IMAGERY OBTAINED FROM MECKLENBURG
COUNTY GIS, 2020.
WI
N
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A

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SOUTH TRYON STREETW
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WINNIFRED STREET
PARKING DECK
S:\AAA-Master Projects\Collett Capital - CTT\CTT-001 Centro Railyard\Post Up-fit Sampling (FZR-001)\Figures\Site Map.dwg, FIG 2, 6/2/2021 7:38:03 AM, sperry
UP
UP
DN
STAIR #2
LOBBY
ELEC.
COMMERCIAL
07
COMMERCIAL
08
COMMERCIAL
09
COMMERCIAL
10
COMMERCIAL
11
COMMERCIAL
12
COMMERCIAL
13
COMMERCIAL
14
COMMERCIAL
15
ELECTRICAL
PUMP
ELEV
#2
VESTIBULE STORAGE
DATA
MECH.
WOMEN'S
MEN'S
750.50'
F-1
F-2
OP-2
OP-1
OP-3
OP-4
OP-5
UP UP
UP
UP DNUPSTAIR #1 STAIR #2
TRASH
FITNESS
LEASING
COMMERCIAL01
COMMERCIAL02 COMMERCIAL03 COMMERCIAL04 COMMERCIAL05 COMMERCIAL06
PACKAGE
MAIL LOBBY
ELEC.
COMMERCIAL07 COMMERCIAL08 COMMERCIAL09 COMMERCIAL10 COMMERCIAL11 COMMERCIAL12
COMMERCIAL13
COMMERCIAL14
COMMERCIAL15
ELECTRICAL
PUMP
ELEV
#1
ELEV
#2
VESTIBULE VESTIBULE
DATA
MECH.
STORAGE
DATA
MECH.
WOMEN'S
MEN'S
WOMEN'S
MEN'S
750.50'750.50'
F-1
F-2
OP-2
OP-1
OP-3
OP-4
OP-5
REVISION NO. 0
JOB NO. CTT-001
DATE: 4-5-22
FIGURE NO. 3
CENTRO RAILYARD
1425 WINNIFRED STREET
CHARLOTTE, NORTH CAROLINA
PROPOSED SUB-SLAB VAPOR AND INDOOR AIR SAMPLE LOCATION MAP
LEGEND
EXTENT OF VAPOR BARRIER
SLOTTED 3" DIA SCH 40 PVC PIPE
SOLID SCH 40 PVC PIPE (3" OR 4" DIA,
REFER TO VIMS LAYOUT)
LOCATION OF VERTICAL RISER AND
APPROXIMATE LOCATION OF TURBINE FAN
ON ROOFTOP
LOCATION OF PRESSURE MONITORING
POINT
PROPOSED INDOOR AIR SAMPLE
LOCATION - LEVEL 1
PROPOSED INDOOR AIR SAMPLE
LOCATION - LEVEL 2
2923 South Tryon Street-Suite 100
Charlotte, North Carolina 28203
704-586-0007(p) 704-586-0373(f)
License # C-1269 / #C-245 Geology
NOTES:
1.LAYOUT SHOWS GROUND FLOOR OF SOUTHWESTERN
APARTMENTS ONLY.
2.VIMS MODIFICATIONS TO SUB-SLAB PIPING AND VAPOR
BARRIER IN AREA OF COMMERCIAL SPACE 12
DOCUMENTED IN "REQUEST FOR VIMP MODIFICATIONS"
DATED MARCH 1, 2021.
SEE NOTE 2
PROPOSED SUB-SLAB VAPOR SAMPLE LOCATION
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Appendix A

Level 1 and Level 2 Floor Plans