22034-18-032 Fairey Finishing PLant VIMS Monitoring Letter

lFrerracon
2401 Brentwood Road, Suite 107
Raleigh, North Carolina 27604
November 11, 2022
North Carolina Department of Environmental Quality
Division of Waste Management - Brownfields Section
1646 Mail Service Center
Raleigh, North Carolina 27699-1646
Attn: Kelly Johnson
Re: VIMS Monitoring Report
Fairey Finishing Plant Brownfields Project
1604 E. Lawson Street, Durham, Durham County, NC
Brownfields Project ID: 22034-18-32
Terracon Project No. 70197104
Dear Mr. Johnson:
P [phone]
F [phone]
Terracon.com
On behalf of Durham Technical Community College (DTCC), Terracon Consultants, Inc.
(Terracon) is pleased to submit these monitoring results for the Vapor Intrusion Mitigation
System (VIMS) located at the above -referenced site. Per the North Carolina Department of
Environmental Quality (NCDEQ) Vapor Intrusion Guidance, Terracon checks the vacuum
readings from the active VIMS approximately every month and reports the results to the North
Carolina Brownfields Program on a quarterly basis. The following table summarizes vacuum
readings at the monitoring points located in the building from July 2021 to October 2022:
Point ID VP-01
VP-02
VP-03
VP-04
VP-05
VP-06
7/26/2021
-1.090
-1.077
-1.073
-1.081
-1.057
-1.064
8/31/2021
-1.214
-1.215
-1.210
-1.221
-1.223
-1.232
9/28/2021
-0.639
-0.626
-0.640
-0.635
-0.645
-0.632
10/26/2021
-0.593
-0.577
-0.587
-0.589
-0.594
-0.582
11/29/2021
-0.445
-0.417
-0.440
-0.441
-0.453
-0.431
12/30/2021
-0.450
-0.419
-0.450
-0.446
-0.444
-0.440
1 /27/2022
-0.503
-0.478
-0.498
-0.500
-0.505
-0.485
2/25/2022
-0.510
-0.491
-0.510
-0.509
-0.513
-0.501
3/21/2022
-0.668
-0.650
-0.663
-0.662
-0.672
-0.651
4/26/2022
-0.535
-0.522
-0.540
-0.531
-0.543
-0.526
5/31/2022
-0.848
-0.836
-0.854
-0.842
-0.859
-0.848
7/6/2022
-0.530
-0.500
-0.525
-0.523
-0.529
-0.513
10/31 /2022
-0.395
-0.347
-0.391
-0.397
-0.397
-0.386
Note: Units are in kilopascals
Facilities I Environmental I Geotechnical I Materials 1

VIMS Monitoring Report I Revision 1.0
Fairey Finishing Plant Brownfields Project I Durham, North Carolina
November 11, 2022 1 Terracon Project No. 70197104
r Terracon
The system was activated in February 2021 and the building has been occupied since Fall
2021. Vacuum readings from February 2021 to June 2021 are summarized in the VIMS
Monthly Monitoring Report dated July 13, 2021 (Terracon, 2021). The locations of the vapor
monitoring points and vent risers are shown in Exhibit 1.
In general, the vacuum measurements appear to be stabilizing over time, although seasonal
variations were observed. Decreases in pressure may also be due to increased permeability
of the subsurface due to continued drying of the subgrade and/or potential blockages of the
VIMS roof vent. During the next pressure monitoring event, Terracon or DTCC maintenance
staff will check the VIMS roof vents for blockages. In general, vacuum measurements at each
of the vapor monitoring points exceeded a pressure differential of 4 pascals, and thus the
VIMS is considered sufficiently depressurized per the NCDEQ Vapor Intrusion Guidance
(NCDEQ, 2018). If you have any questions, please do not hesitate to contact us at 919-873-
2211.
Sincerely,
Terracon Consultants, Inc.
Ethan C. Dinwiddie, PG
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Senior Staff Geologist ®ZH QCCAR®I�,aa=
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Donald R. Malone, PE (NC)
Senior Engineering Consults;
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J11Labriziani, RSM
Environmental Department Manager
Attachments: Exhibit 1 — Vapor Mitigation System Plan
Facilities I Environmental I Geotechnical I Materials 2

VIMS Monitoring Report I Revision 1.0
Fairey Finishing Plant Brownfields Project I Durham, North Carolina Terracon
November 11, 2022 1 Terracon Project No. 70197104
References:
North Carolina Department of Environmental Quality, 2018. Vapor Intrusion Guidance,
Division of Waste Management, Version 2, March.
Terracon Consultants, Inc. (Terracon), 2020a. Vapor Intrusion Mitigation Design Submittal,
Fairey Finishing Plant, New Applied Technologies Building, 1604 E. Lawson Street
Durham, Durham County, NC. February 28.
Terracon, 2020b. Vapor Intrusion Mitigation System Pilot Testing and Vapor Sampling
Brownfields Work Plan, DTCC Applied Technologies Building, 1604 E. Lawson Street
Durham, Durham County, NC. April 23.
Terracon, 2021. VIMS Monthly Monitoring Report, Fairey Finishing Plant Brownfields
Project, 1604 E. Lawson Street, Durham, Durham County, NC, Brownfields Project
ID: 22034-18-32. July 13.
Facilities I Environmental I Geotechnical I Materials 3

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