17060 Perfecting WP IAS-Approval 20180723

July 23, 2018

Sent Via E-Mail
David Stoner
Shield Engineering 4301 Taggart Creek Road
Charlotte, North Carolina 28207
[e-mail]

Subject: Work Plan Approval Perfecting Service Division
332 Atando Ave, Charlotte, Mecklenburg County
Brownfields Project No. 17060-13-060
Dear Mr. Stoner,
The Department of Environmental Quality (DEQ) Brownfields Program received the Revised
Additional Assessment Work Plan dated July 20, 2018 for the above referenced Brownfields
Property. DEQ Brownfields reviewed this document, and determined that comments made by DEQ Brownfields to the previous versions of this work plan (dated June 29) have been incorporated as requested. Therefore, DEQ Brownfields approves the Work Plan dated July 20, 2018.

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 questions about this correspondence or require additional information, please feel free to contact me by phone at 704/661-0330 or by email at
[e-mail]

Sincerely, Carolyn Minnich
Carolyn Mininch
Brownfields Project Manager
ec: Toole, William [e-mail]
John D. [e-mail]

Additional Assessment Work Plan
Automotive Group, LLC
332 Atando Avenue July 2018
Charlotte, North Carolina

TABLE OF CONTENTS
Page No.
1.0 INTRODUCTION.................................................................................................................. 1

1.1 Site Location and Description ...................................................................................... 1
1.2 Background and Purpose ............................................................................................. 1

2.0 SCOPE OF WORK ................................................................................................................ 1

2.1 Indoor Air Sampling .................................................................................................... 2
2.2 Additional Soil Sampling ............................................................................................. 3
2.3 Brownfields Receptor Evaluation ................................................................................ 4
2.4 Additional Assessment Summary Report .................................................................... 4

3.0 SCHEDULE .......................................................................................................................... 4

ATTACHMENTS

Figure 1 – Site Location/Tax Map
Figure 2 – Proposed Indoor Air and Sampling Locations
Brownfields Property Receptor Survey
Additional Assessment Work Plan
Automotive Group, LLC
332 Atando Avenue July 2018
Charlotte, North Carolina Page 1 of 4
1.0 INTRODUCTION
1.1 Site Location and Description
The subject site is located at 332 Atando Avenue in Charlotte, NC. See the attached Site
Location/Tax Map as Figure 1. The site is comprised of one parcel identified in the Mecklenburg
County Geographic Information System as Parcel ID 08506108. The property is approximately 4.24
acres in size and currently contains four (4) interconnected buildings totaling approximately 78,500
square feet of space. The property is owned by the Automotive Group, LLC. The site has
historically been used for various forms of metals products manufacturing. Current operations at the
site are an automobile parts warehouse, with some associated parts installation services provided to
customers, and associated business offices.

1.2 Background and Purpose
The Automotive Group, LLC is pursuing a Brownfields Agreement with the North Carolina
Department of Environmental Quality (NCDEQ). In a letter dated March 12, 2015, the NCDEQ
Brownfields Project Manager requested assessment information that the NCDEQ could use to
evaluate the site risks. Shield Engineering, Inc. (Shield) conducted the soil and groundwater
sampling as detailed in the initial Sampling Work Plan approved by the NCDEQ on February 26,
2016. Thereafter, we prepared and submitted to the NCDEQ a Sampling and Analysis Report dated
May, 2017 summarizing the soil and groundwater results. The NCDEQ responded by requesting a
sub-slab vapor study largely to assist in determining if there is a source of chlorinated volatile
organic compounds (VOCs) under the buildings at the location, and what effects any detected VOC
vapors may have on the indoor air at the location.

Shield submitted a Revised Vapor Intrusion Work Plan dated January 18, 2018 which was
subsequently approved for implementation by the NCDEQ on January 19, 2018. The work scope
outlined in the document was executed in February 2018. The results were summarized in the report
titled Sub-Slab Vapor Study Report dated April 3, 2018. NCDEQ reviewed the report and
determined that data gaps still exist and requested additional assessment work outlined in their April
10, 2018 comment letter. This Revised Additional Assessment Work Plan outlines the additional
assessment activities that will be executed.

2.0 SCOPE OF WORK
This Revised Additional Assessment Work Plan is based on the above mentioned correspondence and
follow-up discussions between Shield and Carolyn Minnich. Ms. Minnich requested indoor air
sampling, some sub-slab soil sampling, completion of a Brownfields Receptor Survey, and
preparation of a summary report discussing the work done with the results. Ms. Minnich further
requested that if there are any elevated indoor air sampling results, copies of that data be submitted to
her immediately. Figure 1 shows the initial proposed locations to be sampled.

Additional Assessment Work Plan
Automotive Group, LLC
332 Atando Avenue July 2018
Charlotte, North Carolina Page 2 of 4
2.1 Indoor Air Sampling
We will generally follow the NCDEQ Vapor Intrusion Guidance dated March 2018 (Guidance)
during the collection of the indoor air samples. Per the Guidance, we will conduct a Building Survey
and Pre-Sampling Evaluation. These surveys were conducted during the sub-slab sampling so a
baseline database exists to compare with any new information. It is known that indoor and
background potential sources of volatile organic vapors exist at the site. These sources were not
removed during the sub-slab sampling. Further evaluation will be made to assess if any potential
background sources can be moved away from sampling zones or eliminated entirely. It would be
ideal to sample when the heating, ventilation, and air conditioning system is not operating if that will
be possible at the time.

Sample point locations will coincide with the locations of the sub-slab samples previously collected.
These locations are shown on Figure 2. Since the intent of this work is to evaluate indoor breathing
air, sample canisters will be located in the normal breathing zone (4.5 feet to 6 feet off the floor) as
possible, where possible. This is a variation from the sub-slab samples as they were collected at
floor level.

Samples will be collected using 6-liter summa canisters. Each summa canister will have a flow
controller set to collect an eight (8) hour (minimum) sample. Pre- and post-collection vacuum
readings will recorded on each canister. We will end the sampling period with at least minus five (5)
inches of mercury vacuum remaining in each canister prior to closing the canister valves.
Temperature and relative humidity data will also be collected when the sample collection starts and
finishes.

Quality assurance/quality control (QA/QC) measures will include collecting at least one (1) outdoor
“background” air sample per the Guidance to identify possible outside sources of VOC vapors. The
background sample will also be collected from a breathing zone height (4.5-6 feet). The sample will
be an eight (8) hour minimum duration sample collected while other field sampling is completed.
The location will correspond to the regional upwind direction and be in the area between Buildings 4
and 5. See Figure 2. Pre- and post-sampling vacuum readings of the canisters will be documented.
Canisters which indicate a pre-sampling vacuum reading greater than 10% lower than what the
laboratory notes on the delivery paperwork will not be used. We will have minus five (5) inches of
mercury vacuum remaining in the canisters upon completion per the Guidelines. The vacuum
reading of each canister will be recorded by the laboratory upon receipt of the canisters at the lab.

Additional QA/QC measures will include collecting one (1) duplicate indoor air sample. The
duplicate sample will be collected from the AG-2 sample location because this location exhibited the
highest concentration of tetrachloroethene (PCE) in the sub-slab sampling event. The location is also
potentially related to AG-4 the location that exhibited the second highest concentration in the sub-
slab sampling event, although AG-4 is in a different building section. The samples will be located
Additional Assessment Work Plan
Automotive Group, LLC
332 Atando Avenue July 2018
Charlotte, North Carolina Page 3 of 4
using field measurements to fixed structures in the building since a global positioning system (GPS)
device will not work within a building.

The samples will be delivered under proper chain of custody to Pace Analytical Services, a NC
certified laboratory. The indoor air samples will be analyzed by EPA Method TO-15 with only
tetrachloroethene (PCE), trichloroethene (TCE), vinyl chloride (VC), 1,1-dichlorethene (1,1-DCE),
and cis-1,2-dichloroethene (cis-1,2 DCE) being reported as requested in the April 10, 2018 NCDEQ
Comment Letter. The detection levels for each parameter will be requested to meet the Inactive
Hazardous Sites Branch non-residential vapor intrusion soil gas screening levels. Level II QA/QC
data packages will be requested.

Upon receipt of the laboratory results, Shield will review the indoor air data and compare the results
to the Inactive Hazardous Sites Branch (IHSB) Non-Residential Vapor Intrusion Screening Levels.
If any data is determined to exceed any of the aforementioned screening levels, the laboratory report
will be submitted to NCDEQ prior to completion of the summary report.

2.2 Additional Soil Sampling

During the Pre-Sampling Evaluation conducted to determine the locations for the sub-slab vapor
samples, two previously unidentified rooms were located. These rooms contained a waste oil storage
unit which may be a crude separator, an evaporator for the waste oil, and a concrete-patched
rectangular area with what appeared to be previous floor drains. It was agreed that this discovery
represents a new Area of Concern (AOC).

Because of the observed structures and the stained nature of the concrete floor, sub-slab soil samples
from this AOC were requested to be conducted by the NCDEQ. An attempt will be made to advance
two (2) soil borings on the hydraulically upgradient and downgradient sides of the concrete patched
rectangular area inside the building. The attempt will be made to advance the borings as close as
possible to the borders of the area. If the borings cannot be advanced inside the building, two
borings will be advanced outside of the building. Those locations will be selected in the field with
emphasis placed on trying to locate the borings on two different sides of (straddling) the AOC. The
soil sample locations will be measured from fixed structures.

Each boring will be advanced to a depth of approximately three (3) to eight (8) feet, depending on
the ability to hand auger to eight (8) feet. Soil cuttings from the borings will be classified, logged in
the field and screened with a photoionization device (PID) for organic vapors. Cuttings with no
organic vapor readings will be put back in the borings upon completion. Otherwise cuttings will be
placed into a drum for proper disposal. Two soil samples will be collected from one boring and one
soil sample will be collected from the other boring. The boring with two (2) soil samples will have
one shallow sample from zero (0) to six (6) inches collected for analyses. The two (2) deeper soil
samples to be collected for analyses will be from the sample intervals containing the highest PID
Additional Assessment Work Plan
Automotive Group, LLC
332 Atando Avenue July 2018
Charlotte, North Carolina Page 4 of 4
reading or the bottom of the borings.

The soil samples collected for analyses will be submitted under proper chain of custody to Pace
Analytical Services. The soil samples will be analyzed for volatile organic compounds (VOCs) by
EPA Method 8260, semi-VOCs (SVOCs) by EPA Method 8270, and the eight (8) RCRA Metals
plus hexavalent chromium by EPA Method 6020/7471/7196 as requested in the April 10, 2018
NCDEQ Comment Letter. Level II QA/QC data packages will be requested with qualifiers such as
estimated values (J flags) noted. For QA/QC purposes, a trip blank will accompany the sample
bottles and samples during shipping. The trip blank will be analyzed for VOCs only.

2.3 Brownfields Receptor Evaluation

At the request of the NCDEQ, Shield will gather the required information to complete the attached
Brownfields Property Receptor Survey. The completed receptor survey will be submitted with the
Additional Assessment Summary Report, discussed below.

2.4 Additional Assessment Summary Report

Once the indoor air sampling data is received, it will be reviewed and if the previously mentioned
conditions exist, submitted to NCDEQ. The air data will be compared to the IHSB Non-Residential
Vapor Intrusion Screening Levels. The soil sample data will be reviewed and compared to the
Industrial/Commercial Health Based Preliminary Soil Remediation Goals (PSRGs). The QA/QC
data will be reviewed and evaluated.

All of the sampling data will be summarized in a report containing a description of field activities,
tabulated data in comparison to applicable screening levels, and the laboratory data packet with
applicable QA/QC documentation. A site plan with well locations, locations of sample points, and
current site structures will be provided. Concentration map(s) for contaminants detected above
applicable standards will be provided.

We will also make the requested revisions to the Sub-Slab Vapor Sampling Report and submit it
with the estimated “J” values from the laboratory along with a table of historical analytical data.

3.0 SCHEDULE
This Work Plan is being submitted to the NCDEQ for approval. Once the NCDEQ approves the
Work Plan, the Indoor Air Sampling and Soil Sampling will be scheduled with the Automotive
Group, LLC. Shield will notify the NCDEQ of the date the field work is scheduled. We anticipate
the field work taking three (3) days to complete with laboratory results available within two weeks
after the sampling. Data evaluation and our report of findings should take about two weeks to
complete once the laboratory data is received. We will strive to have the report submitted within one
month of receiving Work Plan approval.