22010_Glenwood Square_VIAWP_20200610

_ .._ = Bloc83 Phase 2 Brownfields Project
Raleigh, North Carolina
Proposed Soil Vapor Sampling Work Plan
January 24, 2020; Revised June 10, 2020
(Page 1 of 3)
GTA Associates, Inc. (GTA), at the request of Glenwood Two, LLC ("Client"), has
prepared a Soil Vapor Sampling Work Plan for the properties located at 621 and 701 Hillsborough
Street, Raleigh, North Carolina, which are included in the Bloc83 Phase 2 Brownfields Project
("subject property"). This Work Plan has been prepared as requested by the North Carolina
Department of Environmental Quality (NCDEQ), as discussed verbally on December 5, 2019, and
as part of Brownfields Project Number 22010-18-092.
The subject property is located south of Hillsborough Street and north of West Hargett
Street, between Glenwood Avenue to the east, and south Saint Mary's Street to the west, within
the city limits of Raleigh, Wake County, North Carolina. The subject property is comprised of five
parcels of land addressed as 615, 621, 623, 701, and 709 Hillsborough Street, and 11 South Boylan
Avenue. The parcels were previously occupied by five commercial structures containing vacant
office space (709 Hillsborough Street and 11 South Boylan Avenue), office space occupied by a
non-profit organization (615 Hillsborough Street), a restaurant (623 Hillsborough Street), a vacant
automobile repair shop (701 Hillsborough Street), and a retail facility and residence (621
Hillsborough Street). The buildings located on the subject property during previous field activities
have been removed.
1.0 INTRODUCTION
GTA previously prepared Phase II Environmental Site Assessments (ESAs) for the six
parcels included in the Brownfields Agreement (BFA), and identified two USTs and seven
geophysical anomalies consistent with USTs. Ten USTs were removed from the site in September
and October 2019. The UST Closure Report has been submitted to NCDEQ under separate cover.
The Phase II ESAs identified naphthalene in soil at concentrations above the NCDEQ Preliminary
Soil Remediation Goals (PSRGs) and in groundwater above the 02L groundwater standards. None
of the soil vapor samples contained concentrations above the Commercial SVISLs Commercial
Soil Vapor Intrusion Screening Levels (CSVISLs); however, tetrachloroethylene (PCE) was
detected in three samples at concentrations up to 87 µg/m3, below the SVISL of 3,500 micrograms
per cubic meter (µg/m3), and trichloroethene (TCE) was detected in three samples at
concentrations up to 20 µg/m3, below the SVISL of 180 ug.m3.
In addition, during recent excavation and construction activities at the site, petroleum -
impacted soil and groundwater was encountered on the western portion of the site.
2.0 SOIL VAPOR SAMPLING
Per the attached email from Mr. Kelly G. Johnson, P.G., with NC Department of
Environmental Quality Division of Waste Management, dated July 3, 2019, it is understood that
vapor sampling will be produced for the subject property to document the existing site conditions,
and that no vapor mitigation measures will be required/installed.
At the request of NCDEQ, GTA proposes to install sub -slab soil vapor sample points at 12
locations within the two proposed buildings (see attached Figure 1: Proposed Soil Vapor Sampling
Plan). The vapor sampling points will be constructed using VaporPino sample pins, installed in

_ ..- = Bloc83 Phase 2 Brownfields Project
Raleigh, North Carolina
Proposed Soil Vapor Sampling Work Plan
January 24, 2020; Revised June 10, 2020
(Page 2 of 3)
5/8" holes drilled through the concrete floor slab and extending approximately 12 inches from the
top of the floor slab in a flush mount configuration with a secured metal cover to allow additional
sampling rounds, if necessary. The patented VaporPin® sampling point provides an air -tight seal
through the existing concrete slab. The sample locations will be located 5 feet away from walls,
joints, utilities, and/or cracks in the slab, if possible. Sample locations #1 through #6 will be
sampled in June 2020, locations #7 through 9 will be sampled in September 2020, and locations
#10 through #12 will be sampled after the tenant moves in but prior to occupancy.
The VaporPin® will be connected to a full enclosure shroud, which encloses the sample
point and entire sample train. The sample train will consist of laboratory -cleaned 1/4-inch
NylaFlow tubing from the sample pin or bentonite borehole seal connected to a laboratory -cleaned
three-way valve, then to a flow controller/regulator set for a 4-hour sample period, and then to a
1-liter (or greater) laboratory -cleaned Summa canister. The shroud will be filled with helium (He)
to a concentration of at least 65% He, and monitored using a helium flow -through meter and hand
pump. Once the shroud is filled with He, the sample train will be purged using a hand pump or
peristaltic pump through a three-way valve installed in the sample train. The sample train will be
purged for at least five minutes and the He content of the purged air will be continuously monitored
using the He meter. Once the leak test is complete, the three-way valve will be turned to allow the
soil vapor sample to enter the Summa canister, starting the sample period. The He concentration
inside the shroud will be recorded at the start and end of the purging activities for each sample
point. New dedicated tubing and fittings will be used for each sample point. A duplicate sample
will be collected during each sampling event, using either a t-splitter or collected immediately after
closing the first canister.
Once the leak test is complete, the three-way valve will be turned to allow the soil vapor
sample to enter the Summa canister, starting the sample period. The sampling is considered
complete when the canister vacuum drops to less than 5 inches mercury (10" Hg) vacuum but not
to 0" Hg.
At the conclusion of the sampling period, the canisters will be sealed, removed, and
submitted under Chain -of -Custody protocol to GTA's North Carolina -certified laboratory for
analysis of VOCs by United States Environmental Protection Agency Method TO-15. The
laboratory will document the received canister vacuums.
3.0 REPORTING
GTA will prepare a report describing the field activities, a figure showing sample locations,
sample results, photographs, field notes, and a copy of the laboratory report with Chain of Custody
documentation. A table documenting He concentrations during purging activities in the shrouds
and the Hg vacuum at the end of the sampling event and at the laboratory for the canisters will be
included in the report. Laboratory results summary tables will include laboratory reporting limits
and comparisons to the NCDEQ Residential VI Screening Levels for soil gas, as appropriate.
Laboratory detection limits will also be presented in the summary tables in order to compare to
also compare to NCDEQ Residential VI Screening Levels for soil gas. A conservative risk

„, .„ Bloc83 Phase 2 Brownfields Project
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` Raleigh, North Carolina
Proposed Soil Vapor Sampling Work Plan
January 24, 2020; Revised June 10, 2020
(Page 3 o 3
calculation will be generated for each building based on calculations using the NCDEQ risk
calculator using the maximum compound concentration of each detected compound.
GTA will conduct a confirmatory sampling event approximately six months after building
occupancy. This confirmatory sampling event is tentatively planned to include resampling
locations #1, #2, #3, #5, #7, #8, 99, #10, #11, and #12. However, depending on the compounds
detected in this initial sampling event, GTA may request that NCDEQ reduce the number of post -
occupancy confirmatory samples. If results from the post -occupancy confirmatory sampling event
are consistent with this initial sampling event, no further sampling will be required.
The report will be signed and sealed by a North Carolina licensed Professional Geologist
or Professional Engineer.
Work Plan reviewed by:
W
W. Shawn Sullivan, P.E.
Associate
Attachments:
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Figure 1 —Proposed Soil Vapor Sampling Plan (11 "x17 ”, color)
Email — dated July 3, 2019, prepared by Kelly G. Johnson, P.G., with NCDEQ
1\Laurelldocs\Prcject Files`2020\35200786 Bloc 83 Soil Vapor Sampling\Bloc 83 Soil Vapor Sampling Work Plan - Revised for NCDEQ
comments.docx

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Chou, Shiehan
From: Stukes, Mary Katherine H. <[e-mail]>
Sent: Thursday, February 6, 2020 2:33 PM
To: Ryan Blair
Subject: FW: [External] RE: Glenwood Square VI Land Use Restriction
From: Johnson, Kelly G <[e-mail]>
Sent: Wednesday, July 3, 2019 2:18 PM
To: Stukes, Mary Katherine H. <[e-mail]>
Cc: Nicholson, Bruce <[e-mail]>
Subject: RE: [External] RE: Glenwood Square VI Land Use Restriction
***Caution: External email***
Mary Katherine — So far we've only used the compliance review letter for submitted engineering designs and I think for
this site, my email reply below should be sufficient.
This email serves as confirmation that DEQ will not require vapor intrusion mitigation measures to be installed in the
currently planned non-residential buildings, as described in the site plans attached to the approved EMP based on the
soil gas data reported in the Phase II ESA dated Jan 9, 2019 (revised March 12, 2019). However, DEQ will require sub -
slab sampling after the buildings are constructed and prior to occupancy to document what site conditions will be
present going forward.
A work plan for the sub -slab soil gas sampling event should be submitted to the Brownfields Program with enough time
for review and comment (approx. 2 months before the sampling event). We can work together to outline the number of
required samples in the future.
As you mentioned, if redevelopment plans change in the future such that residential use is anticipated, we will need to
revisit vapor mitigation requirements.
Thanks and I hope you have a great 4th!
-Kelly
Mr. Kelly G. Johnson, P.G.
Brownfields Project Manager
NC Department of Environmental Quality
Division of Waste Management
919.707.8279 (Office)
Kelly.JohnsonLncderin gov
Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.
Mary Katherine Stukes
Partner
R

Three Wells Fargo Center 1 401 South Tryon Street Suite 3000 1 Charlotte, NC 28202
Office: 704.335.9495 1 Fax: [phone] vcard map
Visit our website at
www.parkerpoe.com
From: Stukes, Mary Katherine H. [mailto:[e-mail]]
Sent: Wednesday, July 3, 2019 1:58 PM
To: Johnson, Kelly G <[e-mail]>
Cc: Nicholson, Bruce <[e-mail]>
Subject: [External] RE: Glenwood Square VI Land Use Restriction
External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to
[e-mail]
Kelly,
Cody Cannon sent me the attached "compliance letter" as an example in connection with a project we're working on
together. Would it be possible for you to put together something similar for the Glenwood Square project? I think a
reply email to my earlier email would be fine, too, but this format may be DEQ's preference.
Thanks!
Mary Katherine
Mary Katherine Stukes
Partner
0 ;-
Three Wells Fargo Center 1 401 South Tryon Street
Office: 704.335.9495 1 Fax: [phone] vcard
Visit our website at
www.parkerpoe.com
From: Stukes, Mary Katherine H.
Suite 3000 1 Charlotte, NC 28202
map
Sent: Monday, July 1, 2019 3:26 PM
To: Johnson, Kelly G <[e-mail]>
Cc: Bruce Nicholson ([e-mail]) <[e-mail]>
Subject: Glenwood Square VI Land Use Restriction
Kelly,
Following up on my voicemail, I'm writing in reference to the land use restriction regarding vapor intrusion in the
attached draft Notice of Brownfields Property (LUR "h"). Could you please confirm by reply email that DEQ will not
require vapor mitigation measures to be implemented in connection with construction of the planned improvements, as
described in the site plans attached to the approved Environmental Management Plan?

We understand that if redevelopment plans change in the future such that residential use is anticipated, we may need
to revisit the question of whether vapor mitigation will be required for such a use, but in the meantime would like DEQ's
written determination that our planned redevelopment meets the requirements of LUR "h" such that vapor intrusion
mitigation measures are not required.
Thanks,
Mary Katherine
Mary Katherine Stukes
Partner
704.335.9495
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