25097_Eno Industrial WP 2022-08-29

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park
1420 Old Oxford Road; 1225, 1507, and 1539 Hamlin Road
Durham, North Carolina
Brownfields Project Name: Eno Industrial Park
Brownfields Project No. 25097-21-032
S&ME Project No. 218154

July 22, 2022
North Carolina Department of Environmental Quality
Division of Waste Management, Brownfields Program
217 West Jones Street
Raleigh, North Carolina 27605
Attention: Ms. Shristi Shrestha via email: [e-mail]
Brownfields Project Manager
Reference: Work Plan for Soil, Groundwater and Soil Gas Sampling
Welcome Venture Park/Eno Industrial Park
1420 Old Oxford Road, 1225 Hamlin Road, 1507 Hamlin Road and 1539 Hamlin Road
Durham, Durham County, NC
Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154
Dear Shristi:
S&ME, Inc. (S&ME) on behalf of our client, Welcome Venture Park LLC (Client, WVP), is submitting this Work Plan
to conduct assessment and limited source removal activities at the above -referenced site. WVP plans to improve
the Site under the North Carolina Department of Environmental Quality (NCDEQ) Brownfields Program (NCBP).
This Work Plan is intended to collect soil, groundwater, and soil gas samples from selected areas to support
development design and considerations regarding possible exposures and environmental management of soil,
groundwater, and soil gas during redevelopment.
If you have any questions, or comments, about the enclosed Work Plan please contact the undersigned.
Sincerely,
S&ME, Inc.
Lucas Barroso-Giachetti, PE, CHMM Samuel P. Watts, PG
Senior Environmental Engineer Principal Geologist/Senior Environmental Consultant
Ibarroso(d)smeinc.com swatts(o)smeinc.com
Enclosure: Work Plan for Soil, Groundwater, and Soil Gas Assessment dated July 22, 2022
Cc: Sharon Eckard (sharon.eckard@ncdenr ciov) — NC Brownfields Program
S&ME, Inc. 13201 Spring Forest Road I Raleigh, NC 27616 1 p 919.872.2660 1 www.smeinc.com

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
p Brownfields Project Name: Eno Industrial Park
�aJA Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
CERTIFICATION
Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park
1420 Old Oxford Road; 1225, 1507, and 1539 Hamlin Road Durham, North Carolina
Brownfields Project Name: Eno Industrial Park
Brownfields Project No. 25097-21-032
S&ME Project No. 218154A
I, Samuel P. Watts , a Licensed Geologist for S&ME, Inc. , do hereby certify this work plan was prepared by me
or under my direct supervision.
Samuel P. Watts, P.G.
Principal Geologist
NC Licensed Geologist No. 1806
S&ME, Inc. is licensed to practice engineering in North Carolina. The firm's license number is C-145.
S&ME, Inc. is licensed to practice geology in North Carolina. The firm's license number is F-0176.
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
Brownfields Project Name:
Eno Industrial Park
III
Brownfields Project No.: 25097-21-032
S&ME
Project No. 218154A
Table of Contents
CERTIFICATION.........................................................................................................................................................ii
1.0
Introduction.....................................................................................................................34
1.1
Proposed Development...............................................................................................................56
1.2
Data Gaps......................................................................................................................................56
2.0
Scope of Work..................................................................................................................67
2.1
Basis and Approach.....................................................................................................................67
2.2
Project Management, Health and Safety Plan, and Coordination.........................................78
2.3
Schedule...........................................................................................................................................8
3.0
Sampling Methodology.................................................................................................89
3.1
Limited Source Removal of Electric Transformer Area..........................................................89
3.2
Site -Wide Soil Sampling............................................................................................................940
3.3
Borrow Area Soil Sampling.......................................................................................................940
3.4
Groundwater Sampling...........................................................................................................1044
3.5
Soil Gas Sampling.....................................................................................................................1242
3.5.1
Sample Locations.........................................................................................................................1242
3.5.2
SGI Sampling Train Setup and Helium Leak Test Methodology...................................................12
3.5.3
Soil Gas Sampling Methodology.....................................................................................................14
4.0
Laboratory Analysis....................................................................................................1514
5.0
Quality Assurance/Quality Control.........................................................................
15
5.1
Field and Laboratory Control Duplicates.................................................................................15
5.2
Sampling Equipment...................................................................................................................15
5.3
Sample Custody............................................................................................................................16
5.4
Laboratory Analytical Report.....................................................................................................16
6.0
Investigative Derived Waste (IDW) Management and Disposal
..........................16
7.0
Reporting..........................................................................................................................16
8.0
References.........................................................................................................................17
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I I Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
Table of Contents (cont'd)
List of Figures
Figure 1 —Topographic Map
Figure 2 — Proposed Sampling Locations with Historical Soil Gas Samples
Figure 3 — Borrow Pit Area Sample Locations
List of Tables
Table 1 —Sample Point Information
List of Attachments
Sheet C-3.0 — Overall Storm Drainage & Grading Plan (02/24/2022)
Sheet No. 1 — Preliminary Earthwork Heat Map (06/23/2022)
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
III Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
1.0 Introduction
S&ME, Inc. (S&ME) on behalf of our client, Welcome Venture Park, LLC (Client, WVP), is submitting this Work Plan
to conduct soil, groundwater and soil gas assessment and limited source removal activities at the Brownfields
Project Site: Welcome Venture Park (Brownfields Project No.: 25097-21-032). Our client, WVP, intends to develop
the Site under the North Carolina Department of Environmental Quality (NCDEQ) Brownfields Program (NCBP).
The referenced property is located at 1420 Old Oxford Road, 1225 Hamlin Road, 1507 Hamlin Road and 1539
Hamlin Road, Durham, Durham County, North Carolina, and is owned by WVP. A topographic map, depicting the
project site and surrounding vicinity is provided as Figure 1.
According to the Brownfields Property Application (dated November 4, 2021), the site is approximately 160 acres
and is comprised of Durham County Tax Parcels 0833-02-89-5258, 0844-01-10-2331, 0843-01-09-6498 and 0833-
02-99-6163. Based on the Phase I Environmental Site Assessment (ESA) prepared by S&ME during 2021, the
following Recognized Environmental Conditions (RECs) were identified with the subject property:
• The pole -mounted transformer observed on -site represents a REC. Between the 1930s and the 1970s,
transformers were sometimes manufactured with polychlorinated biphenyls (PCBs) and synthetic fire-
resistant chemicals used in the electrical insulating fluids. Review of historical sources indicate the on -site
structures (and likely the associated electric power supply) were built during this period. Absent markings
that would identify the transformer as non -PCB containing, or identify the manufacturer, or the
manufacture date, the transformer can be presumed to contain PCBs and other constituents of concern
(COCs). Furthermore, the transformer appeared to be in poor condition and located over exposed soils.
• Based on a review of regulatory documentation, the Mitsubishi Electric release of volatile organic
compounds (VOCs) from a former waste storage building has impacted the groundwater on the subject
property with tetrachloroethene (PCE), trichloroethene (TCE), cis-1,2-Dichloroethene (DCE) and vinyl
chloride. This documented VOC impact to groundwater on the subject property represents a REC. Due to
the proximity to the subject property and the established fate and transport mechanisms associated with
chlorinated solvent releases, there is also a possibility for vapor encroachment.
• Based on a review of regulatory documentation, a release of chlorinated solvents associated with the
Beckmann -Durham -Sandefur State Hazardous Waste Site (SHWS) site is present on the northeastern
adjacent properties. Based on a determined groundwater flow direction to the west, towards the subject
property, this represents a REC. Similar to the Mitsubishi Electric chlorinated solvent release and due to
the proximity to the subject property, there is also a possibility for vapor encroachment.
To further evaluate the RECs identified above, S&ME conducted a Limited Phase 11 ESA during February 2022 for
the subject property. The overall objective of the Phase II ESA was to provide information on possible sediment,
surface water and groundwater contamination at the subject property to help prepare plans for the
redevelopment of the site, preparing an Environmental Management Plan (EMP) for site development and
preparing a Brownfields Agreement (BFA) between NCDEQ and WVP.
Based on the assessment activities completed by S&ME during early 2022, the following findings are presented
below associated with the subject property:
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I I Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
Electric Transformer — The dielectric fluid from the electrical transformer encountered during the Phase I
ESA was sampled for its PCB content. Due to the PCB concentrations reported at less than 50 parts per
million (ppm), the fluid is considered non -PCB material/fluid by the United States Environmental
Protection Agency (USEPA). However, the PCB -containing oil and PCB -contaminated equipment should
be properly disposed of in an environmentally sound manner by a licensed disposal company. S&ME
estimates that as much as 10 gallons of dielectric fluid may have been released from the electric
transformer. A limited excavation and proper disposal of soil from this area is recommended to address
the low-level PCB impact. Following completion of the excavation activities, confirmation soil sampling
should be conducted to document removal of the potentially PCB -impacted soils.
Surface Water - The upstream (SW-1) and downstream (SW-3) surface water locations were dry at the
time of the assessment. Therefore, surface water quality could not be gathered during the Phase II ESA.
Sediment - Based on the findings of the assessment, the sediment at the site does not pose an
unacceptable risk to human health and should not hinder the redevelopment of the subject property.
Soil - Background concentrations of arsenic and chromium were similar to the assessment samples S&ME
collected in the buried debris area and the burn area. Based on this comparison, we believe these
detections are naturally occurring and are not from an anthropogenic source(s). Based on the findings of
the assessment, the soil at the site does not pose an unacceptable risk to human health or the
environment and should not hinder the redevelopment of the subject property.
Groundwater - S&ME recommends that the on -site monitor wells be surveyed so groundwater
potentiometric maps may be prepared depicting the elevation of the local groundwater table and
groundwater flow direction may be calculated. The analytical results of the assessments indicate the
groundwater is not impacted with contaminants above their respective screening levels, beyond those
areas previously identified by the groundwater assessment and remediation activities associated with the
release of VOCs by Mitsubishi Electric to the southeast, with the exception of metals. Arsenic, barium,
chromium, lead and selenium were reported above their applicable North Carolina 2L Groundwater
Quality standards.
Soil Gas — VOCs — The COCs associated with nearby Mitsubishi Electric and the nearby Beckmann -
Durham -Sandefur sites (VOCs), were not detected in the soil gas samples collected at the site above their
applicable practical quantitation limits (PQLs), supporting that these two documented groundwater
incidents do not appear to adversely affect soil gas quality at the subject property.
• Soil Gas —1,3-butadiene - The source of 13-butadiene and chloroform detections above their respective
Non -Residential Soil Gas Screening Levels (SGSLs) is unknown. According to the EPA document, Locating
and Estimating Air Emissions From Sources of 1,3-Butadiene, November 1996, the primary sources of 1,3-
butadiene are the manufacturing of synthetic elastomers (rubbers, latex, etc.), producing raw materials for
nylon, and in the combustion of petroleum products, among other sources. The possibility exists for the
detections of 1,3-butadiene across the site to be a result of external sources and not from the historical
site operations. Another possibility for the detections of 1,3-butadiene is a "false -positive" by the
laboratory's ion chromatograph.
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
r Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
• Soil Gas — Chloroform — Chloroform is a trihalomethane typically found in chlorinated municipal water
supplies. Federal drinking water standards limit total trihalomethanes (i.e., chloroform,
bromodichloromethane, dibromochloromethane, and bromoform) to 80 micrograms per liter (pg/L) (US
EPA, 2009). Chloroform is ubiquitous in indoor air and often found in soil gas samples due to irrigation
using chlorinated water or leaks from water lines.
1.1 Proposed Development
The prospective developer intends to redevelop the property with 1.1 million to 1.5 million square feet of light
industrial warehouses. The project will involve multiple buildings occupied by a variety of tenants. Attachment A
includes two preliminary site development figures depicting the entire 160-acre site development plans.
♦ Sheet C-3.0 — Overall Storm Drainage & Grading Plan (02/24/2022)
• Sheet No. 1 — Preliminary Earthwork Heat Map (06/23/2022)
Phase 1 of the development is outlined with a red dashed line; encompasses approximately 61 acres; and will
include roads, utilities, and five single -story commercial/light industrial buildings. Anticipated construction of
Phase 1 is scheduled to start Q3/Q4 of 2022, with an anticipated 24-month completion schedule. Future phases
will be dictated by market conditions and tenant demand. But would likely be after the 24-month construction
wraps up in Phase 1. The five buildings in Phase 1 have the following preliminary designations and square footage.
Building C — 100,000 sf
Building D — 103,200 sf
Building E — 74,400 sf
Building F — 192,000 sf
Building G — 25,200 sf
At this time, the PD anticipates soil will be borrowed ("cut") from the central portion of the site to fill portions of
the Phase 1 development to achieve the desired elevation. Max depth of cut in the borrow area will be
approximately 30 feet BGS at the planned SCM south of Buildings I and J in the attached master grading plan.
The anticipated excavation will decrease sharply at the proposed building footprints, with a max cut of about 19
feet BGS. The design of the stormwater control ponds will be prepared after receiving the results of groundwater
testing at these locations.
1.2 Data Gaps
Based on S&ME's review of historical environmental reports and our assessments complected during 2021 and
2022, the purpose of this assessment is to address the data gaps regarding (1) confirming groundwater quality at
the site in support of the BFA and (2) evaluating soil gas quality beneath the proposed building footprints shown
in Figure 2 to determine if there is a need for a vapor intrusion mitigation system (VIMS).
In preparation for the submittal of this Work Plan, S&ME conducted a conference call on June 9, 2022 with Ms.
Shristi Shrestha and Ms. Sharon Eckard of NCDEQ to discuss the elements of the assessment and request
preliminary comments on the proposed approach. As a result of this meeting with NCDEQ, S&ME has included
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
Brownfields Project Name: Eno Industrial Park
i
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
the requested Borrow Pit soil sampling scope of work in addition to our previously presented assessment for soil,
soil gas and groundwater.
2.0 Scope of Work
2.1 Basis and Approach
As indicated previously, WVP will be improving the site with industrial warehouse buildings. S&ME is proposing
to conduct soil, groundwater, and soil gas sampling within Site in support of the EMP that will provide the best
practices and design considerations, as applicable, for the Site's development. This Assessment Work Plan was
prepared in general accordance with Minimum Requirements Checklist for Site Assessment Work Plans and Reports
(NCDEQ Brownfields Program - February-2022November 2018) and Vaaor Intrusion Assessment _Work Plan _& _ _ , Formatted: Font: italic
Report Checklist (NCDEQ Brownfields Program - March 2022).
The results of this investigation will be used to further evaluate soil, groundwater and soil vapor quality at the Site
and provide NCBP with recommendations for approval that will be the basis of the EMP. S&ME will perform the
following scope, to further assess onsite media that may have been impacted by historical use of the site and
surrounding properties.
Limited Source Removal of Electric Transformer Area - S&ME proposes to conduct a limited excavation of the
surficial soils identified with potential impacts from electrical transformer di -electric fluid. Prior to mobilizing to
the site to complete the source removal, S&ME will collect confirmation sidewall and bottom of the excavation soil
samples to define/confirm the dimensions of the proposed excavation. Based on an assumed radial dispersion of
the historical electrical transformer di -electric fluid and to incorporate an over -excavation approach of impacted
surficial soils (top 12 inches), the excavation area is assumed to be approximately 20 feet by 20 feet.
Site -Wide Soil Sampling - S&ME will install up to six soil borings using either hand augers or direct -push
technology (DPT) from within the upper 10 feet below ground surface (BGS). S&ME will select six locations where
the soil gas implants (SGIs) are proposed across the site, depicted on Figure 3, to screen soil quality and confirm
the February 2022 Phase II ESA results via laboratory analysis.
In addition, S&ME will collect soil samples from selected deeper depth intervals (approximately 20 feet to 30 feet
BGS) for potential analysis during the installation of monitoring wells MW-18 and MW-19 located within the
proposed stormwater control measure (SCM) ponds, which be the subject of excavation or "cuts" from existing
grade to approximately 30 feet BGS.
Results of the soil sampling will be used to assess the absence of contaminants of concern in the soils across the
site and/or identify areas that may require impacted media management during redevelopment.
Borrow Area Soil Sampling - S&ME provided a copy of Sheet C3.0 - Overall Storm Drainage and Grading Plan
prepared by the PD's civil engineering consultant, WithersRavenel, during the conference call on June 9, 2022 with
NCDEQ. This engineering plan is provided in Attachment A and outlines the proposed Phase I development area
(identified with a red, dashed line) and the associated borrow area (identified with a blue, solid -dashed line).
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
S&ME notes that the anticipated construction of Phase 1 is scheduled to commence during the Third Quarter
2022 to Fourth Quarter of 2022. Based on information provided by WithersRavenel, we understand that the
following areas within the blue -outlined Borrow Pit area will be excavated as follows:
♦ Areas within the approximate Building I and Building J footprints will be excavated or "cut" to a depth
of approximately 20 feet below current ground surface.
♦ The areas south of Buildings I and 1, featuring proposed SCM ponds, will be excavated or "cut" to a
depth of approximately 30 feet below current ground surface.
S&ME's approach to evaluate soil quality within the borrow area includes dividing the approximately 20-acre area
into 5 approximately 4-acre sub -areas. Each sub -area will be sampled using a grid pattern with soil borings
screening soil quality at ten -foot depth intervals to the proposed excavation or "cut" depth. Figure 3 shows the
approximate limits of each sub -area and the grid -based soil boring locations to screen soil quality within the
Borrow Pit area. Results of the soil sampling and analysis will be used to assess the absence of contaminants of
concern in the Borrow Pit soils and/or identify areas that may require impacted media management during
redevelopment.
Groundwater Assessment— S&ME will install five permanent groundwater monitoring wells, MW-15 through
MW-19, during this assessment. The monitoring well locations are depicted on Figure 2 and are located in the
proposed stormwater control measures. The locations have been selected to address areas of concern and fill in
groundwater analytical data gaps for the site proposed site development. Results of the additional groundwater
sampling will be used to assess the absence of contaminants of concern in the groundwater across the site and
identify areas that may require impacted media management during redevelopment.
Soil Gas Assessment— S&ME will collect up to 13 soil gas samples (SVI-C-1 and SVI-C-2, SVI-D-1 through SVI-D-
4, SVI-E-1 through SVI-E-3, SVI-F-1 through SVI-F-3 and SVI-G-1) during this assessment within the approximate
footprints of the proposed structures. The SGI locations are depicted on Figure 2 and have been selected to (1)
evaluate soil gas quality potentially impacted by the documented offsite VOC groundwater plumes and (2)
determine the need for a VIMS beneath the proposed structures.
2.2 Project Management, Health and Safety Plan, and Coordination
Prior to mobilizing to the site to conduct the proposed sampling, S&ME will conduct the following:
♦ Update a previously prepared a health and safety plan to comply with currently proposed site activities, in
accordance with 29 CFR 1910.120 as required by the Occupational Safety and Health Administration
(OSHA).
♦ Contact NC 811 and contract with a private utility location company prior to mobilizing to the site to
locate public underground utilities at the site.
♦ Contract a North Carolina -licensed surveyor to survey elevations at the existing ground surface where soil,
groundwater, and soil vapor samples are to be collected.
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
2.3 Schedule
The field assessment activities are planned to begin in July 2022 (pending NCDEQ approval of this Work Plan), and
will be completed within approximately three to four weeks. S&ME anticipates submitting a draft summary of
findings approximately one week after receipt of the final laboratory results for the soil, groundwater and soil gas
investigation. The general site assessment schedule is presented below.
Site Assessment Schedule
Task
Duration
Project Management, Health and Safety Plan, and Coordination
As Needed
Groundwater, Soil and Soil Gas Sampling
1 week
Laboratory Analysis
2 to 3 weeks
Limited Source Removal of Electric Transformer Area
1 week
Prepare Soil, Groundwater, and Soil Gas Assessment Report
2 weeks
3.0 Sampling Methodology
Table 1 provides a summary of the planned sample point information (sample media, sample location/depth, no.
of samples, proposed analyses, and objective). Sampling and assessment will be conducted in general accordance
with the following guidance manuals:
♦ NCDEQ Inactive Hazardous Sites Branch (IHSB), Guidelines for Assessment and Cleanup of
Contaminated Sites (July 2021)
♦ NCDEQ Division of Waste Management, Vapor Intrusion Guidance (March 2018)
U.S. Environmental Protection Agency (EPA) Region IV Science and Ecosystem Support Division (SESD)
Field Branches Quality System and Technical Procedures (most recent version)
♦ NCDEQ Brownfields Proaram. Minimum Reauirements Checklist for Site Assessment Work Plans and
Reports (November 2018)
♦ NCDEQ Brownfields Program, Vapor Intrusion Assessment Work Plan & Report Checklist (March 2022). ,
3.1 Limited Source Removal of Electric Transformer Area
S&ME proposes to conduct a limited excavation of the soils identified with potential impacts from electrical
transformer dielectric fluid. Prior to mobilizing to the site to complete the source removal, S&ME will collect
confirmation sidewall and bottom of the excavation soil samples to define the dimensions of the proposed
excavation. Based on an assumed radial dispersion of the historical electrical transformer di -electric fluid and to
incorporate an over -excavation approach of the impacted surficial soils, the excavation area is assumed to be
approximately 20 feet by 20 feet removing the surficial or top 12 inches of impacted soils.
S&ME will collect confirmatory soil samples from the sidewall and bottom of the planned excavation diSEF to sail
samples using either hand augers or direct -push technology (DPT) at the following approximate depths: one -foot
BGS, two feet BGS and three feet BGS. The one -foot surficial confirmation soil samples will be analyzed for PCB
Aroclorss by EPA Method 8082 VOCs by EPA Method 8260B, and SVOCs by EPA Method 8270a44d
July 22, 2022
Formatted: Font: Italic
Formatted: Font: Italic

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I I Brownfields Project Name: Eno Industrial Park
i
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
(VPH EPH) Methods. The confirmation soil samples collected from the two -foot interval and three-foot interval
will be submitted to the laboratory and placed on "hold" pending the analysis results from the surficial 1-foot BGS
interval. The deeper intervals on "hold" will be analyzed for the applicable parameter if the PCBs, VOCs and
SVOCs and/or /EPH concentrations are reported above their applicable health -based standards. Additionally,
soil samples will be collected for analysis of PCB Congeners by EPA Method 1668. These samples will also be
collected from the sidewall and bottom of the planned excavation; submitted to the laboratory; and placed on
"hold" pending the analysis results from the PCB Aroclors. Once the final confirmation samples, from the lowest
excavated interval, have been identified, PCB Cogeners will be taken off hold for analysis.
In addition to the laboratory analysis of the confirmation soil samples, S&ME will conduct a qualitative screening
by collecting an aliquot of soils and placing them into a container with clean water. The container will be agitated
and the surface of the water within the container will be observed for the presence of oil globules, which would
serve as an indicator that dielectric fluids or oils are present within the soil matrix of the soil aliquot. The area of
the electric transformer is shown on Figure 2 at the former location of soil boring SS-1.
errOnce the laboratory analysis have confirmedatiOR of -the dimensions of the limited source removal area,
S&ME will mobilize to the site with an environmental contractor and conduct the soil excavation. Excavation
activities are anticipated to be completed within one working day and will involve the excavation of the impacted
area with a track -mounted excavator and directly loading into a dump truck for transportation of the impacted
soils offsite. When the pre -determined excavation dimensions have been achieved and confirmed by S&ME staff,
the impacted soils will be transported offsite to a licensed soil waste facility under a Non -Hazardous Waste
Manifest.
S&ME will document the final dimensions of the excavations, prepare a photographic log documenting the source
removal process and provide a copy of the signed Non -Hazardous Waste Manifest provided by the licensed solid
waste facility receiving the impacted soils.
3.2 Site -Wide Soil Sampling
S&ME will collect up to six discrete soil samples and one duplicate soil sample using either hand augers or direct -
push technology (DPT) from within the upper five to ten feet BGS. Representative portions of each one -foot
interval will be collected, logged, and screened using a photoionization device (PID). A separate portion of the
soil sample should be used for the laboratory analysis and the field screening. The interval exhibiting the highest
organic vapor concentrations will be collected for laboratory analysis, as detailed below. The potential soil
sampling locations are depicted on Figure 2. The proposed soil samples will be collected and analyzed for VOCs
by EPA Method 826013, semi -volatile organic compounds (SVOCs) by EPA Method 8270, the 8 Resource
Conversation and Recovery Act (RCRA) metals by EPA Method 6010/7470 and hexavalent chromium by EPA
Method 71996.
3.3 Borrow Area Soil Sampling
As discussed in Section 2.1, S&ME will divide the approximately 20-acre borrow area into five approximately 4-
acre sub -areas. Each sub -area will be sampled using a grid pattern with soil borings screening soil quality at ten -
foot depth intervals to the proposed excavation or "cut" depth. Figure 3 shows the approximate limits of each
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
sub -area and the grid -based soil boring locations to screen soil quality within the borrow area. Sub -areas 1
through 4 located within the Building I and Building J footprints will include four soil borings that will be advanced
to depths of approximately 20 feet BGS. Sub -area 5 will include four soil borings that will be advanced to a depth
of approximately 30 feet BGS.
Discrete soil samples will be collected at randomized depths from each 10-foot depth interval at each soil boring
location. Discrete soil samples collected at each depth interval will conducted in general accordance with the
Lnoctive Hazardous Sites Program Guidelines for Assessment and Cleanup dated _October '^' 5July 2021. S&ME Formatted: Font: italic
proposes to collect composite soil samples from the proposed Borrow Pit soil area as follows:
♦ Sub -Areas 1 through 4 -Composite samples from the ground surface to 10 feet BGS and 10 feet BGS
to 20 feet BGS. An example of the soil sample IDs is sample "SA-1-0-10" screening soil quality within
Sub -Area within the surficial interval from the ground surface to 10 feet BGS.
♦ Sub -Area 5- Composite samples from the ground surface to 10 feet BGS, 10 feet BGS to 10 feet to 20
feet BGS and 20 feet to 30 feet BGS.
S&ME will collect the soil samples using either hand augers or direct -push technology (DPT). Soil samples will be
logged and classified to identify soil types according to the Unified Soil Classification System (USCS) and field -
screened for volatile organic compounds (VOCs) using a hand-held photo -ionization detector (PID).
The soil samples will be appropriately labeled, placed on ice within a secured cooler and delivered the laboratory
under standard chain -of -custody protocols for analysis. The proposed soil samples will be collected and analyzed
for VOCs by EPA Method 8260B, SVOCs by EPA Method 8270, the 8 RCRA metals by EPA Method 6010/7470 and
hexavalent chromium by EPA Method 7196. A Geographic Positioning System (GPS) will be used to record the
location of the soil borings.
3.4 Groundwater Sampling
S&ME proposes to install five permanent wells for the collection of groundwater samples, to evaluate
groundwater quality. S&ME will use a track -mounted Geoprobe® (or equivalent) drill rig with hollow -stem augers
to install the five permanent groundwater wells for the collection of groundwater samples at the locations shown
on the attached Figure 2.
After reaching termination depths in each of the soil borings, the wells will be constructed by installing a minimum
of 10-foot section of two-inch diameter 0.010-inch slotted PVC well screen fitted to sufficient riser pipe to bring
each temporary -well to the ground surface. Filter sand will be poured between the casing and boring annulus to a
depth of approximately one foot above the top of the screen. A one -foot bentonite seal will be placed on top of
filter pack.
ca44 •voll mpag- e-tAfter wells have been constructed, the depth to groundwater shall be measured using a water
level indicator probe that emits an audible tone when in contact with water. The water level indicator probe will be
decontaminated between each depth to water measurement. After measuring water levels in the temperary
sampling peiatwells, S&ME will purge each well using a submersible peristaltic pump with new dedicated Teflon -
July 22, 2022 10

Work Plan for Soil, Groundwater, and Soil Gas Assessment
r Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
IIIr Brownfields Project Name: Eno Industrial Park
r Brownfields Project No.: 25097-21-032
i
S&ME Project No. 218154A
lined tubing in each tenMaefwF -well. The tubing depth will be selected to intersect the well screen in each
terieraFy-well.
Prior to collecting groundwater samples for laboratory analysis, each well shall be purged of stagnant standing
water in the casing so that the sample retrieved is representative of the groundwater environment surrounding
the well. The volume of water to be removed to obtain a representative sample may consist of one of the
following, based on the recharge rate of the well:
a) To dryness in a slow recharging well; or
t — Formatted: Numbered + Level: 1 + Numbering Style: a, b,
c, ... + Start at: 1 + Alignment: Left + Aligned at: 0.25" +
b) An adequate purge is achieved when the pH. specific conductance, and temperature of the indent at: o.s"
potable/ground water have stabilized and the turbidity has either stabilized or is below ten Nephelometric
Turbidity Units (NTUs). Although ten NTUs is normally considered the minimum goal for most water
sampling objectives, lower turbidity has been shown to be easily achievable in most situations, and
reasonable attempts should be made to achieve these lower levels. Stabilization occurs when, for at least
three consecutive measurements, the pH remains constant within 0.1 Standard Unit (SU), specific
conductance varies no more than approximately ten percent, and the temperature is constant (±1.0°C); or
c) If, after three well volumes have been removed, the chemical parameters have not stabilized according to
the above criteria, additional well volumes (up to five well volumes), should be removed. If the
parameters have not stabilized within five volumes, it is at the discretion of the project leader whether or
not to collect a sample or to continue purging. If, after five well volumes, pH and conductivity have
stabilized and the turbidity is still decreasing and approaching an acceptable level, additional purging
should be considered to obtain the best sample possible, with respect to turbidity.
Prior to collecting samples for laboratory analysis, S&ME i.vill. measure field parameters consisting of pH,
temperature, spec 0 fic conductivity, dissolved oxygen, and turbidity after each volume of groundwater is purged, or
° .The depth -to -
water measurements and purge parameter measurementss, and the time the measurements were observed, will
be recorded on field collection sheets -logs and will also be tabulated in the technical report.
Groundwater pumped from the wells will be pumped via low -flow techniques directly into laboratory -supplied
containers, labeled, and placed into an insulated cooler for shipment, under chain -of -custody procedures, to a
North Carolina -certified laboratory for analysis. The groundwater samples will be analyzed for VOCs by EPA
Method 826013, SVOCs by EPA Method 8270, the 8 RCRA metals by EPA Method 6010/7470 and hexavalent
chromium by EPA Method 7196. One blind duplicate sample will be collected and analyzed for the same
parameters as the record samples.
Upon receipt of the laboratory analyses and approval from the NCDEQ, Brownfields Program, S&ME will re-
mobilize to the site and abandon the permanent monitoring wells in accordance with industry standards.
July 22, 2022

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I I Brownfields Project Name: Eno Industrial Park
i
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
3.5 Soil Gas Sampling
3.5.1 Sample Locations
S&ME proposes to install up to 13 SGIs for the collection of soil gas samples. S&ME will use a track -mounted
Geoprobe® drill rig with direct push technology to install the SGIs for the collection of soil gas samples. The SGIs
will be installed at the locations shown on the attached Figure 2. The depths of the SGIs will be based upon the
final floor elevation of the proposed structure. The targeted depth of each of the SGIs will be approximately one
to two feet below the level of the final floor elevation. If groundwater is encountered prior to the intended depth
of the SGI, then S&ME will install the SGI no deeper than two feet above the apparent groundwater depth. See
Table 1 for the planned depths of the soil gas samples.
Once the boring for the SGI has reached the desired depth, the six-inch stainless steel screen SGI will be installed.
The SGI will be fitted with 0.25-inch Teflon tubing and installed at the base of the boring. Filter sand will be
placed from the bottom of the boring to six inches above the top of the screened interval. A hydrated bentonite
seal will be placed over the top of the filter sand to the ground surface to form a seal. The tubing will be capped
and covered at the ground surface.
During the advancement of the soil borings, soil samples will be continuously collected in five-foot long
disposable acetate -plastic sleeves that line the hollow stainless -steel sample probes. The soils from each boring
will be visually classified by S&ME personnel and field -screened with a calibrated photo -ionization detector (PID)
for the presence of VOCs. The soil samples will be screened in approximate two -foot increments utilizing VOC-
free media. A separate portion of the soil sample should be used for the laboratory analysis and the field
screening.
3.5.2 SGI Sampling Train Setup and Helium Leak Test Methodology
Following installation of the SGIs, S&ME will perform a leak test of each SGI. A plastic shroud will be placed
overtop the SGI installation area. The tubing from the SGI will be fitted through the shroud and attached to a
Tedlar bag. S&ME will then inject helium (tracer) gas into the plastic shroud. Three volumes of air will be purged
from each SGI, associated tubing, and borehole annulus (similar to a personal air monitoring pump or peristaltic
pump) at a rate less than 200 milliliters per minute and collected in a Tedlar bag. A Sensidyne Go -Cal Air Flow
Calibrator will be plumbed in the exhaust tubing to measure continuous air flow rates during the purging process.
Following completion of the purging process, the Tedlar bag will be screened with a helium detector. If the tracer
gas is not detected in the Tedlar bag at a concentration greater than 10% of the concentration within the shroud
array, then the SGI will be considered leak free. If leaks are detected, the SGI will be re -installed and re -tested for
leaks. Following a successful leak test, each SGI point will be capped for approximately 48 hours.
No sooner than 48-hours after installation of the SGIs, S&ME will return to the site to connect the summa
canisters to the sampling train and perform a helium test of the entire sampling array. S&ME will perform a
second leak test by attaching a brass T-connector to the end of the SGI tubing and connecting a section of Teflon
tubing to one part of the T-connector and another section will be attached to an individually certified one -liter
summa canister. A plastic shroud will be placed overtop the SGI tubing array and summa canister. The other
section of tubing from the T-connector will be fitted through the shroud and attached to a Tedlar bag. S&ME will
then inject helium (tracer) gas into the plastic shroud. The shroud will be filled with helium to a concentration of
July 22, 2022 12

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I I Brownfields Project Name: Eno Industrial Park
i
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
greater than 90%, while a soil gas sample is collected into a Tedlar® bag through the 1/4" Teflon® sample tube for
onsite sample analysis of helium content.
Three volumes of air will be purged from each sampling array (this includes the tubing and borehole annulus)
using a calibrated low flow pump (similar to a personal air monitoring pump or peristaltic pump) at a rate less
than 200 milliliters per minute and collected in a Tedlar bag. A Sensidyne Go -Cal Air Flow Calibrator will be
plumbed in the exhaust tubing to measure continuous air flow rates during the purging process. Following
completion of the purging process, the Tedlar bag will be screened with a helium detector. If the tracer gas is not
detected in the Tedlar bag at a concentration greater than 10% of the concentration within the shroud array, then
the sampling array will be considered leak free. If leaks are detected, the sampling array will be re -built and re-
tested for leaks.
One blind duplicate soil gas sample will be collected and analyzed for the same parameters as the record samples.
The duplicate sampling train will be constructed so that the brass T-connector leading from the end of the SGI
tubing will be connected to an additional T-connector with Teflon tubing. Each end of the additional T-connector
will be connected to an individually -certified one -liter summa canister with Teflon tubing. The helium test of the
entire duplicate sampling array will be performed as described above.
The photograph below is an example of a duplicate sampling train construction.
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Work Plan for Soil, Groundwater, and Soil Gas Assessment
!' Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
3.5.3 Soil Gas Sampling Methodology
Upon determining the sampling array is leak free, the valve to the one -liter summa canister will be opened to
allow the collection of the soil gas samples. The sample collection rate will be set with a one -hour regulator with a
flow rate of less than 200 milliliters per minute. Pressure readings of the summa canisters will be recorded at the
start and end of collection. A residual vacuum of up to -5 inches of mercury will exist in the canister upon
completion of the sampling event. The post sampling vacuum rate will be recorded in S&ME's field
documentation and on the laboratory's chain of custody forms. The laboratory will record receipt pressures of the
summa canisters.
Once the soil gas samples are collected, the samples will be shipped under standard chain -of -custody protocol to
a NELAC certified laboratory for analysis of VOCs by EPA Method TO-15 including naphthalene. S&ME will cap
each sampling point after the soil gas samples have been collected.
Upon receipt of the laboratory analyses and approval from the NCDEQ Brownfields Program, S&ME will re-
mobilize to the site and remove the SGI tubing to approximately one foot below the top of the ground surface
and will fill the top of the boring with soil. Please note that during SGI construction the borehole is filled with
hydrated bentonite clay. The location of the soil gas samples will be recorded with a mapping grade sub -meter
GPS unit.
July 22, 2022 14

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I I Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
4.0 Laboratory Analysis
As noted above, the media samples will be analyzed as summarized below:
• Soil from the SGIs, monitoring well locations, and borrow area - VOCs by EPA Method 8260B, SVOCs by
EPA Method 8270, the 8 RCRA metals by EPA Method 6010/7470, and hexavalent chromium by EPA
Method 71996.
• Soil from the electric transformer area pre -source removal area — PCB Aroclors by EPA Method 8082 PCB
Congeners by EPA Method 1668.- VOCs by EPA Method 826013, and SVOCs by EPA Method 8270and
/aliphatics by the MADEP VPH/EPH Methods
• Groundwater - VOCs by EPA Method 8260B, SVOCs by EPA Method 8270, 8 RCRA metals by EPA Method
6010/7470, and hexavalent chromium by EPA Method 71996.
• Soil gas - VOCs by EPA Method TO-15 (include naphthalene & exclude acrolein).
Samples will be submitted under standard chain -of -custody procedures to a North Carolina -certified laboratory
(air samples to a NELAC-certified laboratory). Reporting Limits/Method Detection Limits will meet applicable
screening criteria (to the extent feasible). Laboratory reports will include reporting of J-Flags to meet criteria.
5.0 Quality Assurance/Quality Control
5.1 Field and Laboratory Control Duplicates
Blind duplicate quality assurance/quality control (QA/QC) samples will also be collected during the soil,
groundwater and soil gas sampling. The QA/QC samples will be collected during the sampling event, at the same
time and location, under the same conditions and submitted in separated containers, with unique sample IDs. The
blind duplicate samples will be analyzed for the same constituents as the record samples, to evaluate analytical
precision, field precision and sample homogeneity.
Due to VOCs being a contaminant of concern, a trip blank will be included in every cooler submitted to the
laboratory with soil/groundwater samples and analyzed for VOCs by EPA Method 8260B. In addition, the
adequate volumes of soil and groundwater will be collected in order to conduct a matrix spike/matrix spike
duplicate (MS/MSD) analysis and the lab reports will be a Level II QA/QC standard.
5.2 Sampling Equipment
The direct push tooling will be decontaminated between soil gas and soil borings and before sampling using an
Alconox®/water soap mixture and water rinse. A new PVC sleeve will be inserted in the direct push rods prior to
collection of soil samples. A new, dedicated SGI will be used for each soil gas sample and new PVC casing will be
used for each tenVerapy-well. Dedicated Teflon -lined tubing will be used in collection of the soil gas samples.
Summa canisters for both the record sample, and the duplicate sample, will be individually certified and pre -
evacuated from the laboratory. Analytical documentation, demonstrating that the individually -certified summa
July 22, 2022 15

Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
S&ME Project No. 218154A
canisters are free of the target compounds down to the project reporting limits, will be obtained from the
laboratory, and provided in S&ME's report.
5.3 Sample Custody
The sampler will complete a chain -of -custody form provided by the laboratory. The sampler will sign where
indicated and record the site identification, sample number, date and time of sampling, matrix code, sample type,
bottle/preservative type, and the analyses requested. When the custody of samples is transferred, the persons
relinquishing and receiving custody will sign, date, and record the time of transfer on the chain -of -custody. If the
samples are shipped using a commercial courier, the bill of lading will become part of the chain -of -custody and
will serve as the signature of the person receiving the samples. Upon receipt of the samples at the laboratory, a
sample custodian will accept custody of the sample and verify that the chain -of -custody is still intact. The
laboratory will maintain the chain -of -custody throughout the analytical and reporting processes. For the soil gas
samples, the laboratory will record the pressure upon arrival of the summa canisters. If the initial vacuum prior to
sampling is in excess of 10% lower than the vacuum documented by the laboratory upon receipt, the cannister will
not be used.
5.4 Laboratory Analytical Report
It is anticipated that routine analytical services will be provided by Pace Analytical Laboratory (soil and
groundwater) and Enthalpy (soil gas) for this project. The laboratories will provide Level II QA/QC analyses for this
project, including the reporting of target analytes at concentrations between the laboratory method detection
limits and the laboratory reporting limits, otherwise known as "1 values". To the extent feasible, the laboratory
method detection limits will not exceed the respective regulatory standards.
6.0 Investigative Derived Waste (IDW) Management and Disposal
Drill cuttings and liquids generated during field activities (purge water) will be containerized in a 55-gallon
drum(s), labeled, secured, and stored onsite. S&ME will collect one composited sample from the drum(s) for VOCs
and chromium and lead, using Toxicity Characteristic Leaching Procedure (TCLP) Extraction. The laboratory data
will be used to determine the appropriate disposal methodology for the contained purge water. S&ME will
coordinate the removal of the drums from the site, if applicable. For purposes of this Work Plan, S&ME has
assumed the IDW will be disposed of as a non -hazardous waste. A copy of the disposal manifest will be included
in our report, if applicable.
7.0 Reporting
Following receipt of the laboratory analyses and results, S&ME will prepare and submit a Technical Report
including the following information:
♦ Introduction: Describes the site conditions at the time of the field activities.
♦ Deviations: S&ME will describe any deviations from this Work Plan.
♦ Results: S&ME will review and tabulate the laboratory analytical results and, if appropriate, will visually
map the results on a drawing(s). The drawing(s) will show the sample locations and analytical results.
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Work Plan for Soil, Groundwater, and Soil Gas Assessment
Welcome Venture Park, Oxford and Hamlin Roads, Durham, NC
I I Brownfields Project Name: Eno Industrial Park
Brownfields Project No.: 25097-21-032
i
S&ME Project No. 218154A
♦ Field Data Collection sheets, including groundwater purging parameters, soil boring logs and soil gas
sampling data.
♦ Quality control data will also be presented and discussed with regard to data quality.
♦ Appendices: S&ME will provide completed photographic logs, a copy of the laboratory analytical
reports, chain -of -custody records, and disposal manifests and applicable permits.
♦ The report will be prepared under the supervision of a North Carolina Licensed Professional Geologist
(PG), or Professional Engineer (PE), and will bear both the firm PG/PE license numbers and individual
license numbers and seals.
8.0 References
Below is a chronological list of previous assessment reports, relevant to the Welcome Venture Park site, which
were considered in preparing this assessment work plan.
♦ January 18, 2019 — Phase I ESA, prepared by Geosyntec Consultants of NC, PC.
♦ April 14, 2020 — Annual Groundwater Remediation Progress Monitoring Report for January 2020 —
Mitsubishi Electric, prepared by Wood Environment and Infrastructure Solutions, Inc.
♦ October 15, 2021 — Phase I ESA, prepared by S&ME, Inc.
♦ February 22, 2022 — Phase 11 ESA, prepared by S&ME, Inc.
July 22, 2022 17

ATTACHMENTS