24053 TA Sherrill VIMP Approval 20210414

From:Schmithorst, William L
To:Frazier, William O
Cc:Matt Murphy; Mack, Elizabeth E.; Chinery, Alex; Hall, Matthew B.; Corbitt, Chris L.; McElveen, Neal
Subject:RE: RE: 24035-20-060_Former TA Sherril Construction Co_VIMS Design - DEQ Comments/Approval
Date:Wednesday, April 14, 2021 3:28:00 PM
Will,
The revised TA Sherrill Construction VIMS Plan dated April 13, 2021 is approved. Please keep the
DEQ apprised of the schedule.

Regards,

Bill Schmithorst
Project Manager, DWM Brownfields Program
North Carolina Department of Environmental Quality
919.441.3606 (Mobile - Primary)
919.707.8159 (Office)
[e-mail]

Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.

From: Frazier, William O [mailto:[e-mail]]
Sent: Tuesday, April 13, 2021 12:50 PM
To: Schmithorst, William L <[e-mail]>
Cc: Matt Murphy <[e-mail]>; Mack, Elizabeth E. <[e-mail]>; Chinery,
Alex <[e-mail]>; Hall, Matthew B. <[e-mail]>; Corbitt, Chris L.
<[e-mail]>; McElveen, Neal <[e-mail]>
Subject: RE: [External] RE: 24035-20-060_Former TA Sherril Construction Co_VIMS Design - DEQ
Comments

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Bill,

I have attached the revised Vapor Mitigation Plan, which includes an updated design and work plans
for post-installation system efficacy testing based on DEQ’s comments on the initial submittal.
Please let us know if you have any questions.

Thanks,
Will

Will Frazier, P.G.
Project Geologist I Environmental Services
Terracon Consultants, Inc
2701 Westport Road I Charlotte, North Carolina 28208
P [phone] I F [phone] I M [phone]
[e-mail] I terracon.com

From: Schmithorst, William L <[e-mail]>
Sent: Thursday, March 25, 2021 11:11 AM
To: Frazier, William O <[e-mail]>
Cc: Matt Murphy <[e-mail]>; Mack, Elizabeth E. <[e-mail]>; Chinery,
Alex <[e-mail]>; Hall, Matthew B. <[e-mail]>; Corbitt, Chris L.
<[e-mail]>; McElveen, Neal <[e-mail]>
Subject: RE: [External] RE: 24035-20-060_Former TA Sherril Construction Co_VIMS Design - DEQ
Comments

Will,
Please see DEQ responses following your questions below. Let me know if you have any additional
questions or need to discuss.

Regards,

Bill Schmithorst
Project Manager, DWM Brownfields Program
North Carolina Department of Environmental Quality
919.441.3606 (Mobile - Primary)
919.707.8159 (Office)
[e-mail]

Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.

From: Frazier, William O [mailto:[e-mail]]
Sent: Wednesday, March 24, 2021 11:03 AM
To: Schmithorst, William L <[e-mail]>
Cc: Matt Murphy <[e-mail]>; Mack, Elizabeth E. <[e-mail]>; Chinery,
Alex <[e-mail]>; Hall, Matthew B. <[e-mail]>; Corbitt, Chris L.
<[e-mail]>; McElveen, Neal <[e-mail]>
Subject: [External] RE: 24035-20-060_Former TA Sherril Construction Co_VIMS Design - DEQ
Comments

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Morning Bill,

We have a few questions regarding DEQ’s comments to the VIMS design submittal:

1) Based on discussions with the PD team, we would like to utilize a Nitra-Seal system that
includes a 40-mil spray-applied layer for the VIMS rather than a 60-mil system as proposed
in the initial submittal. Please see the attached submittal with the Nitra Seal product
specifications. Would DEQ approve this product for use in the VIMS?

Response: The DEQ has no objections to the change as long as it is approved by the project’s NC
licensed design engineer and complies with the manufacturer’s requirements.

2) Could you please elaborate on the objective of installing additional vapor pins at the
requested locations? Was there a particular sample frequency per square footage that you
are shooting for and were these particular locations chosen to provide additional sample
data coverage? We chose the seven proposed vapor pin locations in areas that will be least
obtrusive to future building tenants but still accessible to sample. We can’t locate the pins
within the rental units, and the hallways will be carpeted and relatively highly trafficked, so
we were limited to stairwells and mechanical-type rooms/closets. Given the layout of the
building, our options were limited in the areas you’ve proposed additional pins. If we can
better understand your goal in having pins in these particular locations, we can figure out
the best way to marry those goals with our post-occupancy access constraints/requirements.

Response: The added sampling locations were chosen to provide additional sample data coverage. A
minimal amount of soil vapor sampling was previously conducted at the site, and soil vapor samples
were not collected at the suspected source area. In addition, data from other brownfields projects
have indicated that the extent of VOCs detections in soil vapor can change after a site is redeveloped.
The DEQ is requesting the additional data for protection of public health.

The DEQ understands that the additional samples are proposed in hallways of the proposed building.
According to the VIMS Design Submittal: “Sub-membrane vapor testing will be conducted following
the installation of the VIMS and concrete slab pour, but prior to building interior construction
completion.” The additional proposed vapor pin locations can be abandoned prior to carpeting the
hallways (the original proposed locations will remain). The DEQ is open to approving the relocation
of the requested vapor pin locations as long as they are adequately spaced between the original
proposed locations. If the construction schedule allows, the additional vapor pin locations should
remain until the laboratory results are reviewed in the event additional sampling is needed. Note
that, as with any NC Brownfields Program project, modifications to the sampling plan may be
required if unexpected conditions are encountered.

3) We are concerned with the request for indoor air sampling. As we are all aware, new
building materials will off-gas VOCs that would very likely lead to noisy data where it is
difficult to interpret whether you have a subsurface source or whether concentrations are
coming from those building materials. If initial sub-slab sampling indicates that the air
turnover from beneath the passive system is sufficient to limit build up of VOC
concentrations, then indoor air sampling would be unnecessary as there would not be a
source to enter the building. We’d like to discuss this request further.

Response: It's standard Brownfields Program policy to require indoor air sampling for passive vapor
mitigation systems. The interference issues described above are typically addressed by comparing the
indoor air sample data to the sub-slab soil vapor data. Note that the following is to be added to the
VIMS Design submittal: New construction materials such as paint, carpet, etc., which could be
sources of VOCs in indoor air, may cause interference with Site-specific compounds during indoor air
sampling. Therefore, the construction contractor should be requested to provide safety data sheets
(SDSs) for materials used during construction which will be submitted to DEQ if elevated compounds
are detected in indoor air. At a minimum, the contractor(s) shall not use building materials that
contain the chlorinated solvents PCE or TCE.

The DEQ is open to revisiting the frequency of indoor air sampling after review of the sub-slab
sampling laboratory results. In addition, sub-slab soil vapor samples can be collected and analyzed
first, allowing the indoor air sample laboratory analytical list to potentially be reduced to site specific
compounds, in concurrence with the DEQ. This will further reduce the potential for indoor air
interferences from construction materials.

In regard to the last two questions, it is probably easiest to discuss in real-time. Would you please
let us know your availability to jump on a conference call with the PD team?

Thanks,
Will

Will Frazier, P.G.
Project Geologist I Environmental Services
Terracon Consultants, Inc
2701 Westport Road I Charlotte, North Carolina 28208
P [phone] I F [phone] I M [phone]
[e-mail] I terracon.com

From: Schmithorst, William L <[e-mail]>
Sent: Thursday, March 11, 2021 4:38 PM
To: Frazier, William O <[e-mail]>
Cc: Matt Murphy <[e-mail]>; Mack, Elizabeth E. <[e-mail]>; Chinery,
Alex <[e-mail]>; Hall, Matthew B. <[e-mail]>; Corbitt, Chris L.
<[e-mail]>; McElveen, Neal <[e-mail]>
Subject: RE: 24035-20-060_Former TA Sherril Construction Co_VIMS Design - DEQ Comments

Will,
The DEQ has completed review of the Vapor Intrusion Mitigation System Design Submittal provided
on January 14 and 18, 2021. DEQ comments are included in the attached file.

Please submit a revised plan to my attention and contact me if you have any questions.

Regards,

Bill Schmithorst
Project Manager, DWM Brownfields Program
North Carolina Department of Environmental Quality
919.441.3606 (Mobile - Primary)
919.707.8159 (Office)

Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.

From: Frazier, William O [mailto:[e-mail]]
Sent: Thursday, January 14, 2021 9:20 AM
To: Schmithorst, William L <[e-mail]>
Cc: Matt Murphy <[e-mail]>; Mack, Elizabeth E. <[e-mail]>; Chinery,
Alex <[e-mail]>; Hall, Matthew B. <[e-mail]>; Corbitt, Chris L.
<[e-mail]>; McElveen, Neal <[e-mail]>
Subject: [External] 24035-20-060_Former TA Sherril Construction Co_VIMS Design

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Morning Bill,

Please see the attached VIMS design for Brownfields’ review.

We are sensitive to the Program’s workload and understand there are many projects competing for
time and attention. Based on our current projected redevelopment schedule, we respectfully
request that review of this design be completed by the end of March. Please do not hesitate to
reach out to us with questions regarding the design as the review progresses. If there is any
information we can provide along the way to assist in completing the review, please do let us know.

Thanks,
Will

Will Frazier, P.G.
Project Geologist I Environmental Services
Terracon Consultants, Inc
2701 Westport Road I Charlotte, North Carolina 28208
P [phone] I F [phone] I M [phone]
[e-mail] I terracon.com

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