25054_Mt Gilead VIMS Design Report Rev2 20220629

Hanley Environmental, PLLC
323 Manning Drive
Charlotte, North Carolina 28209
NC Engineering License P-2407
T: [phone]
www.hanleyenvironmental.com

June 29, 2022

Ms. Carolyn Minnich
Brownfields Project Manager
Brownfields Program
North Carolina Department of Environmental Quality

Subject: Vapor Intrusion Mitigation System Design Report – Revision 2
Mt. Gilead Cotton Oil Company Brownfields Property
Mt. Gilead, Montgomery County, North Carolina
Brownfields Project No. 25054-21-062
Hanley Environmental Project Number: PJ22017

Ms. Minnich,

On behalf of Mt Gilead DG, LLC, Hanley Environmental, PLLC is pleased to provide the
enclosed Vapor Intrusion Mitigation System Design Report for the Mt. Gilead Cotton Oil
Company Brownfields Property located in Mt. Gilead, Montgomery County, North Carolina.
This report was originally submitted on May 18, 2022 and has been revised based on
comments provided by NCDEQ on June 28, 2022.

Please do not hesitate to contact me with any questions regarding this submittal.

Sincerely,
David Hanley, PE
Hanley Environmental, PLLC

Hanley Environmental, PLLC
323 Manning Drive
Charlotte, North Carolina 28209
NC Engineering License P-2407
T: [phone]
www.hanleyenvironmental.com

VAPOR INTRUSION MITIGATION
SYSTEM DESIGN REPORT

Mt. Gilead Cotton Oil Company Brownfields Property

Mt. Gilead, Montgomery County, North Carolina
Brownfields Project No. 25054-21-062
Project Number: PJ22017

Revision 2
June 29, 2022
Prepared for:

Mt Gilead DG, LLC
Vapor Intrusion Mitigation System Design Report – Revision 2
Mt. Gilead Cotton Oil Company Brownfields Property
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TABLE OF CONTENTS
TABLE OF CONTENTS i
1.0 INTRODUCTION 1
1.1 Assessment Summary 1
1.2 System Overview and Objectives 3
1.3 Proposed Development Overview 3
1.4 Contact Information 4
1.5 Certification 4
2.0 DESIGN BASIS 5
3.0 QUALITY ASSURANCE/QUALITY CONTROL 7
4.0 PRE-OCCUPANCY EFFECTIVENESS TESTING 8
4.1 Pressure Field Extension Testing 8
4.2 Pre-Occupancy Sub-Slab Soil Gas Sampling 9
5.0 POST-OCCUPANCY EFFECTIVENESS TESTING 10
5.1 Post-Occupancy Monitoring Requirements 10
5.2 Contingency for System Activation 11
6.0 FUTURE TENANTS & BUILDING USES 12
7.0 REPORTING 12
8.0 DESIGN SUBMITTAL EXHIBITS 13
9.0 SPECIAL CONSIDERATIONS FOR RETROFITS 13
10.0 REFERENCES 13

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List of Figures

Figure 1 Site Vicinity Map

List of Appendices

Appendix A VIMS Design Submittal Requirements Checklist
Appendix B Historical Data Summary
Appendix C VIMS Design Drawings and General Specifications
Appendix D Vapor Intrusion Barrier and Vapor Collection System Specifications
Appendix E TO-15 Analyte List

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1.0 INTRODUCTION
This Vapor Intrusion Mitigation System (VIMS) Design Report presents the design of a VIMS
for a proposed building to be constructed at the Mt. Gilead Cotton Oil Company Brownfields
Property (Site ID 25054-21-062) in Mt. Gilead, Montgomery County, North Carolina (the site).
The site is located at 299 Industry Avenue and 0 South Wadesboro Boulevard, and consists
of two parcels (parcel IDs 6593-12-95-4641 and 6593-12-95-3728) with a total area of 3.55
acres. A map depicting the site vicinity is included as Figure 1. The site was formerly part of
an industrial complex that included the Former Mt. Gilead Cotton Oil Company and the
Russell-Harville Hosiery Mill.
The site is being redeveloped by Prospective Developer (PD) Mt Gilead DG, LLC for
commercial use including a one-story retail facility (Dollar General). Hanley Environmental,
PLLC was contracted by the PD to prepare this VIMS Design Report. This report has been
prepared pursuant to the NCDEQ Brownfields Program’s VIMS Design Submittal
Requirements checklist dated July 2021 (Appendix A). The report includes a basis of design
along with system design drawings and specifications, quality assurance/quality control
(QA/QC) procedures, pre-occupancy testing requirements, post-occupancy operation,
maintenance, monitoring (OM&M), and reporting procedures.
1.1 Assessment Summary
Environmental assessment activities performed at the site are summarized in the Phase I
Environmental Site Assessment (ESA) prepared by Emerald, Inc., dated April 22, 2021; the
Phase II ESA prepared by Emerald, Inc. dated May 12, 2021; and the Brownfields Assessment
Report prepared Emerald, Inc. dated April 1, 2022. Data summary excerpts from these
reports are included in Appendix B.
According to these reports, the site was used for parking and storage related to the adjacent
Former Mt. Gilead Cotton Oil Company and the Russell-Harville Hosiery Mill since at least
1940. The Phase I ESA indicated that former cotton oil and hosiery mill facility used unknown
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chemicals and oils in operations. Additionally, an aboveground storage tank (AST) with
unknown contents was located approximately 50 feet from the site boundary. A May 2021
Phase II ESA was performed, which did not identify impacts to site soil from VOCs. Two site
groundwater samples had constituent concentrations exceeding 15A NCAC 02L .0202
standards (2L Standards) including tetrachloroethylene (PCE) with a maximum concentration
of 7.4 micrograms per liter (µg/L), trichloroethylene (TCE) with a maximum concentration of
14.5 µg/L, and vinyl chloride with a maximum concentration of 1.1 µg/L.
Brownfields assessment activities were conducted in February 2022, which included
installation and sampling of one monitoring well, collection of six soil samples, and collection
of two soil gas samples. Results are summarized below.
• Soil analyses identified an arsenic concentration above its Industrial/Commercial
Preliminary Soil Remediation Goal (PSRG) in one sample, but below background
arsenic concentration, indicating that the arsenic was naturally occurring. No volatile
organic compounds (VOCs) or semi-volatile organic compounds (SVOCs) were
detected in soil samples.
• Groundwater assessment activities identified shallow perched water above dry
weathered rock throughout the site. VOCs and SVOCs were not detected in the
samples collected from the one well installed at the site.
• Soil gas samples were collected from approximately five feet below ground surface.
Ten soil gas probes were installed, and groundwater was found to have impacted
eight of the ten probes. Samples were collected from two probes (SG-9 and SG-10),
which were located within the footprint of the planned site building. Analytical results
identified several VOCs in soil gas. PCE was the only compound detected at a
concentration above Non-Residential Soil Gas Screening Levels (SGSLs), with a
maximum concentration of 16,000 micrograms per cubic meter (µg/m3) in the
duplicate sample collected from SG-9). PCE was also detected at a concentration of
3,100 µg/m3 in SG-10, which was just below the Non-Residential SGSL of 3,500 µg/m3.
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• A vapor intrusion risk assessment was performed using the NCDEQ Risk Calculator
by inputting the highest detected soil gas concentrations to evaluate the soil gas to
indoor air pathway for a non-residential receptor. The results indicated an
incremental lifetime cancer risk of 3.7x10-6 and a hazard index of 0.97, which are
below the NCDEQ Brownfields Program’s acceptable risk thresholds (incremental
lifetime cancer risk of 10-4 and hazard index of 1).
Although the results of the vapor intrusion risk assessment did not indicate unacceptable
risk of vapor intrusion in the planned site building, based on the amount of data collected
and planned construction timeframe, the Prospective Developer intends to proactively
install a VIMS at the proposed site building.
1.2 System Overview and Objectives
The objective of the proposed VIMS is to reduce occupant exposure to volatile compounds
originating from subsurface contamination in the planned site building to acceptable risk
levels. This will be achieved by providing a pathway for venting of soil gas from below the
building floor slab to above the building roof, reducing the likelihood of soil gas containing
hazardous chemicals from entering the occupied building spaces.
1.3 Proposed Development Overview
The site was recently vacant and is currently undergoing development for commercial use
with a single story commercial building to be occupied by a Dollar General store. A
preliminary site development plan is included in Appendix B. Planned site features in
addition to the building include a driveway and parking areas, a dumpster enclosure, and a
stormwater detention facility. The majority of the proposed building will be rectangular,
measuring approximately 80 feet by 156 feet, with an attached rectangular entryway
measuring approximately 7 feet by 32 feet, with a total building footprint area of
approximately 12,650 square feet. The building will be constructed with a four-inch thick
slab-on-grade with 18 column footings spaced around the perimeter of the building. The
building footprint will consist of one continuous slab. No grade beams, thickened slab areas,
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or other obstructions to vapor flow are planned inside the slab perimeter. No subgrade
features or vertical walls in contact with soil are planned.
1.4 Contact Information
As specified in the VIMS Design Submittal Requirements checklist, relevant contact
information is provided below.
• Prospective Developer – Mt Gilead DG, LLC, Tom C. James,
[e-mail]
• Brownfields Assessment Consultant – Emerald, Inc., Ronny Lowder,
[e-mail]
• VIMS Design Engineer – Hanley Environmental, PLLC, David Hanley, P.E.,
[e-mail]
• VIMS Installation Contractor – to be determined
• Brownfields Project Manager – Carolyn Minnich, [e-mail]
1.5 Certification
This VIMS design has been certified by a North Carolina licensed Professional Engineer in
accordance with 21 NCAC 56 .1103. The document was originally certified on May 18, 2022,
and revised on May 31, 2022 and June 29, 2022 to address comments provided by NCDEQ.
The VIMS detailed herein is designed to mitigate intrusion of subsurface vapors into the
subject building from known Brownfields Property contaminants in a manner that is in
accordance with the most recent and applicable guidelines including, but not limited to,
NCDEQ Department of Waste Management (DWM) Vapor Intrusion Guidance, Interstate
Technology & Regulatory Council (ITRC) guidance, and American National Standards Institute
(ANSI)/American Association of Radon Scientists and Technologists (AARST) standards. The
sealing professional engineer is satisfied that the design is fully protective of public health
from known Brownfields Property contaminants.
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Use of specific guidance documents in development of this VIMS Design is described in
Section 2.0.
This VIMS Design requires implementation of the specified QA/QC procedures, pre-
occupancy testing requirements, post-occupancy OM&M, and reporting procedures. Failure
to implement these procedures and requirements may limit the system’s effectiveness.
As specified in the Brownfields Property Reuse Act §130A-310.32, implementation of a
brownfields agreement will result in use suitable of the property “fully protecting public
health and the environment instead of being remediated to unrestricted use standards”.
Accordingly, risk-based standards will be used in evaluating system effectiveness and the
proposed VIMS is designed to reduce risk to non-residential receptors to below the NCDEQ
Brownfields Program’s acceptable risk thresholds (incremental lifetime cancer risk of 10-4
and hazard index of 1) for contributions of known volatile compounds originating from
subsurface contamination. These risk thresholds are considered “fully protective of public
health” in the context of this Brownfields property.
This VIMS Design is subject to compliance review by the NCDEQ Brownfields Program. Minor
modifications to the design (e.g., use of equivalent products/materials, minor modifications
to system component locations) will be approved by the engineer and documented in as-
built drawings (Section 7.0). Significant alterations to the VIMS Design (e.g., changes to the
areas to receive mitigation, the number of risers, or the number of monitoring points) will
be submitted to the NCDEQ Brownfields Program in a VIMS Design Report Addendum for
compliance review.
2.0 DESIGN BASIS
The VIMS design was developed in general accordance with design standards contained in
Soil Gas Control Systems in New Construction of Buildings (ANSI/AARST, 2018). System
design drawings and specifications are included in Appendix C.
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The VIMS will provide soil gas control beneath the entirety of the proposed building by
providing a pathway for venting of soil gas from below the building floor slab to above the
building roof, reducing the likelihood of soil gas containing volatile contaminants from
entering the occupied building spaces. The VIMS will operate as a passive system and will
provide venting without the use of electric fans. If warranted based on performance
monitoring data, the system may be converted to an active system in the future with the
addition of electric fans. Contingency measures for conversion to an active system are
included in Section 5.3.
In general, VIMS components will include:
• A vapor intrusion barrier beneath the concrete slab consisting of a 30-mil composite
geomembrane (MonoShieldTM System, manufactured by Land ScienceTM) sealed at
seams, penetrations, and terminations using a fluid-applied nitrile latex and asphalt
emulsion (Nitra-Core, manufactured by Land ScienceTM);
• A gas permeable layer beneath the vapor barrier consisting of at least 4 inches in
depth of washed gravel, with the gas permeable layer enclosed on the top and sides
by the concrete slab or footings;
• A system of vapor collection vents within the gas permeable layer serving as an inlet
for soil gas and providing routing to soil gas exhaust vent pipes;
• Four soil gas exhaust vent pipes (R-1 through R-4) consisting of solid PVC piping
extending from the gas permeable layer beneath the building slab to exhaust outlets
above the building roof;
• Four exhaust outlets at the terminations of exhaust vent riser pipes above the
building roof with slotted caps that draw out soil gas using the Venturi effect;
• Four permanent vacuum monitoring points (VMP-1 through VMP-4) consisting of PVC
piping installed through the slab and vapor intrusion barrier and open to the gas
permeable layer to allow for measurement of pressure field extension and sub-slab
soil gas sample collection from the gas permeable layer following slab installation;
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• Four temporary vacuum monitoring points (TVMP-1 through TVMP-4) consisting of
PVC piping installed through the slab and vapor intrusion barrier and open to the gas
permeable layer to allow for measurement of pressure field extension, which will be
abandoned with NCDEQ approval following pressure field extension testing; and,
• Sealing of potential soil gas pathways from the sub-slab to indoor air including utility
penetrations and cracks in the slab.
Detailed specifications for VIMS components are included in Appendix C (for general VIMS
system specifications) and Appendix D (for installation of the vapor intrusion barrier and
vapor collection vents).
The specified vapor intrusion barrier system was selected based on factors including its
documented resistance to diffusion of volatile chemicals including chlorinated solvents,
constituents of concern and soil gas concentrations documented at the site, and
constructability. Other system design parameters (e.g., gas permeable layer design; type and
placement of vapor collection vents, number and diameter of exhaust vent pipes, number
and placement of VMPs) were based on standards in the Soil Gas Control Systems In New
Construction of Buildings (ANSI/AARST, 2018) and the Standard Plan: Methane Hazard
Mitigation (City of Los Angeles Department of Building and Safety, 2010).
3.0 QUALITY ASSURANCE/QUALITY CONTROL
QA/QC procedures during installation will consist of inspections for compliance with design
specifications. The following inspections shall be performed during construction of the VIMS.
• Sub-slab system components (e.g., gas permeable layer, soil gas inlets and piping) will
be inspected prior to being covered with a vapor intrusion barrier.
• Placement of the vapor intrusion barrier will be inspected prior to pouring the
concrete slabs.
• Smoke testing will be performed in accordance with vapor intrusion barrier
manufacturer requirements.
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• Exhaust riser piping will be inspected prior to covering with drywall or other
finishings.
• Exhaust outlets will be inspected after installation.
Inspections will be performed and documented by personnel under direction of a North
Carolina registered Professional Engineer, including photographs and field logs. Findings
that do not meet specifications will be re-inspected following correction. The PD or its
designee will provide notification to the NCDEQ Brownfields Program at least 48 business
hours prior to inspection.
4.0 PRE-OCCUPANCY EFFECTIVENESS TESTING
Pre-occupancy testing will include pressure field extension testing and sub-slab soil gas
sampling as described in the following sections. Results of pre-occupancy testing will allow
for evaluation of system effectiveness.
4.1 Pressure Field Extension Testing
Pressure field extension testing will be performed prior to building occupancy to verify that
areas below the slab can be effectively influenced by the piping network. Pressure field
extension testing will occur after slabs have been cast. The evaluation will include connecting
one or more fans to exhaust vent piping and measuring the resulting vacuum within the gas
permeable layer at strategic locations. This testing will verify that no changes are needed for
the design of exhaust vent piping assemblies. VMPs will be installed at strategic locations
remotely distant from the exhaust vent pipe risers to evaluate effectiveness and consistency
of vacuum propagation/soil gas transport beneath the building slab.
Testing may be performed before or after riser pipes are extended to the building roof. One
or more fans will be connected to riser pipes to apply a vacuum to the gas permeable layer
and the pressure differential in nearby VMPs will be measured and recorded. The vacuum
measurements will be evaluated for evidence of poor effectiveness and inconsistencies, and
consideration of system modifications will be taken if such evidence is identified. Results of
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pre- or post-occupancy sampling may be considered when evaluating whether system
modifications are warranted.
Pressure field extension testing activities and results will be presented in the VIMS
Installation Report (Section 5.1).
4.2 Pre-Occupancy Sub-Slab Soil Gas Sampling
Four sub-slab soil gas samples will be collected following completion of VIMS installation and
prior to building occupancy to evaluate system effectiveness. One sample will be collected
from each VMP. Sampling will be performed pursuant to the NCDEQ Division of Waste
Management Vapor Intrusion Guidance dated March 2018.
One-liter or six-liter Summa® canisters batch certified by the laboratory will be used to collect
sub-slab soil gas samples. Canisters will be inspected prior to sampling to verify that vacuum
levels are within 10% of the level recorded by the laboratory prior to shipment. Dedicated
tubing and flow controllers will be used at each sample collection point. Each sub-slab
sampling point will be sampled by connecting sample tubing to each VMP. PTFE or nylon
tubing will be used for sample collection. A short length of flexible Tygon® tubing may be
used to connect the VMP to the sample tubing.
Vacuum shut-in testing will be performed at each sample location by closing a valve on the
sample train to prevent airflow from the VMP to the sample train. The valve on the summa
canister will then be opened to confirm no vacuum losses occur in the sample train.
At least three sample train volumes of air will be purged from each sample point prior to
sampling. During purging, the sample canister, tubing, and sample point will be surrounded
with a shroud consisting of a plastic container. The container will be filled with helium to a
concentration of approximately 15% as measured using a Dielectric MGD 2002 helium
detector (or similar). Purged vapors will be collected in Tedlar® bags using a peristaltic pump,
syringe, or lung box. The helium concentration of the vapor in the Tedlar® bags will be
measured. If the concentration of helium in extracted vapors is greater than 10% of the
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helium concentration in the shroud, the sample train connections and sampling point seal
will be reevaluated and improved, and additional helium testing will be performed until an
acceptable result of less than 10% of the shroud helium concentration is measured.
Following purging and leak testing, a soil gas sample will be collected into the sample canister
at an approximate flow rate of 200 mL/min. A target final vacuum level of approximately 5
to 10 inches of mercury (in Hg) vacuum will be used. Canisters will not be allowed to reach
zero vacuum. After sampling, the canisters will be transported under chain-of-custody
protocols via courier to the laboratory for analysis. The soil gas samples will be analyzed for
VOCs by EPA Method TO-15 for compounds previously detected in site soil gas, groundwater,
and soil as listed in Appendix E.
Analytical results will be input into the NCDEQ Risk Calculator to evaluate the soil-gas to
indoor air pathway for non-residential receptors, and results will be compared to NCDEQ’s
acceptable risk thresholds (incremental lifetime cancer risk of 10-4 and hazard index of 1).
Sampling activities will be summarized and results will be presented in the VIMS Installation
Report (Section 5.1). If results warrant additional data collection including indoor air samples,
a Work Plan for additional sampling will be submitted to NCDEQ for approval prior to
sampling.
The building shall not be occupied until approval is provided by NCDEQ based on pre-
occupancy data. This requirement is separate from a certificate of occupancy provided by
local code enforcement or other federal, state, or local occupancy authorizations.
5.0 POST-OCCUPANCY EFFECTIVENESS TESTING
5.1 Post-Occupancy Monitoring Requirements
One additional round of sub-slab soil gas sampling will be performed following building
occupancy. Sampling will be performed approximately six months after pre-occupancy
sample collection in order to evaluate VIMS performance under varied weather/heating and
cooling conditions. Four samples will be collected (one from each VMP) following the
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procedures described in Section 4.2. Sampling activities will be summarized and results will
be presented in a VIMS Post-Occupancy Monitoring Report, which will be submitted to the
NCDEQ Brownfields Program within approximately two months of sample collection. Based
on monitoring results, a request to terminate sampling may be submitted to NCDEQ for
approval. If termination of sampling is approved, VMPs may be permanently abandoned by
filling with non-shrinking cement/grout to reduce the risk of VMPs serving as a preferential
pathway for soil gas to enter the building.
5.2 Contingency for System Activation
If monitoring indicates that the VIMS cannot provide effective vapor intrusion mitigation,
contingency measures will be implemented which provide for conversion of the system from
a passive system to an active system. With an active system, electric fans will be used to place
a vacuum on exhaust vent pipes to depressurize the sub-slab relative to indoor air.
If pre- or post-occupancy monitoring activities indicate that NCDEQ’s acceptable risk
thresholds for indoor air are exceeded for non-residential receptors, (incremental lifetime
cancer risk of 10-4 and hazard index of 1), or if the indoor air TCE concentration exceeds
NCDEQ’s non-residential TCE indoor air inhalation immediate action level (8.8 µg/m3) with
the VIMS operating passively in accordance with this VIMS Design, system activation be
required.
To implement system activation, a North Carolina licensed Professional Engineer will prepare
a VIMS Design Report Addendum to specify installation of electronic fans, low vacuum
alarms, and additional monitoring requirements. The design addendum will be subject to
compliance review by the NCDEQ Brownfields Program. If warranted, interim measures (e.g.,
use of temporary fans or indoor air purification units) may be implemented temporarily
without NCDEQ approval.
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6.0 FUTURE TENANTS & BUILDING USES
Proper operation of the VIMS requires continued adherence to the system OM&M
requirements from future owners, tenants, and occupants. Notification of the presence and
requirements of the system must be given to building tenants and occupants by the owner,
and future owners should be made aware of system requirements. Building modifications
should not alter system components (e.g., riser pipes, exhaust fans, concrete slab, sub-slab
components) without approval from a Professional Engineer. If the vapor intrusion barrier is
exposed or penetrated (e.g., for installation of sub-slab utilities), approval is required.
Approved changes to system components should be conducted under the QA/QC
requirements described in Section 3.0. System changes should be documented in revised as-
built drawings.
7.0 REPORTING
Documentation of construction, deviations from the design, and information on operation,
maintenance, and monitoring (OM&M) of the VIMS will be presented in a VIMS Installation
Report, which will include the following components:
• A description of the system components and objectives;
• A summary of construction QA/QC activities including inspection records (field logs
from each inspection including photographs);
• Results and evaluation of pre-occupancy testing;
• As-built drawings documenting the final locations and construction details of system
components;
• Safety data sheets provided by the PD and/or contractor for chemicals or materials
used during construction that could contribute to background indoor air
concentrations;
• System operation and maintenance requirements;
• System monitoring requirements; and,
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• The following statement from the Professional Engineer: “The VIMS detailed herein is
designed to mitigate intrusion of subsurface vapors into the subject building from
known Brownfields Property contaminants in a manner that is in accordance with the
most recent and applicable guidelines including, but not limited to, NCDEQ DWM
Vapor Intrusion Guidance, ITRC guidance, and ANSI/AARST standards. The sealing
professional engineer is satisfied that the design and its installation are fully
protective of public health from known Brownfields Property contaminants.”
The VIMS Installation Report will be submitted to the NCDEQ Brownfields Program for
conditional occupancy consideration.
8.0 DESIGN SUBMITTAL EXHIBITS
A site vicinity map is included as Figure 1. Site figures including historical sampling locations
and summaries of analytical data are included in Appendix B. Detailed specifications for
VIMS components are included in Appendix C (for general VIMS system specifications) and
Appendix D (for installation of the vapor intrusion barrier and vapor collection vents).
9.0 SPECIAL CONSIDERATIONS FOR RETROFITS
The proposed development does not include retrofit of an existing building. Therefore, this
section is not applicable.
10.0 REFERENCES
American National Standards Institute/ American Association of Radon Scientists and
Technologists, Soil Gas Control Systems In New Construction of Buildings , CC-1000
2018, dated 2018.
City of Los Angeles, Standard Plan: Methane Hazard Mitigation, Revised February 10, 2010.
Emerald, Inc., Phase I ESA, Mt. Gilead Cotton Oil Company, April 22, 2021.
Emerald, Inc., Phase II ESA, Mt. Gilead Cotton Oil Company, May 12, 2021.
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Emerald, Inc., Brownfields Assessment Report, Mt. Gilead Cotton Oil Company, April 1, 2022.
NCDEQ Division of Waste Management Vapor Intrusion Guidance dated March 2018.

FIGURE

APPENDIX A
VIMS Design Submittal Requirements Checklist

APPENDIX B
Historical Data Summary

APPENDIX C
VIMS Design Drawings and General Specifications

R-1
R-4
R-3
R-2
VMP-4
VMP-3
VMP-1
VMP-2
BUILDING FOOTER (DETAIL 4)SLAB TURNED DOWN EDGE (DETAIL 4)VAPOR INTRUSION BARRIER
AND GAS PERMEABLE LAYER
UNDER 4-INCH SLAB (DETAIL 1)
TVMP-1
TVMP-2
TVMP-3
TVMP-4
PROJECT
SHEET TITLE
SHEET NO.CLIENTDATE
PROJECT NO.
DRAWN BY
STAMP
REVISION DATE DESCRIPTION ENG
HANLEY ENVIRONMENTAL, PLLC
323 MANNING DRIVE
CHARLOTTE, NORTH CAROLINA 28209
NC LICENSE P-2407
MT. GILEAD COTTON OIL COMPANY
BROWNFIELDS PROPERTY
MT. GILEAD DG LCC
LEGEND
LOW PROFILE VAPOR COLLECTION SYSTEM (DETAIL 2)
3" SCH 40 PVC SOLID EXHAUST VENT PIPE (DETAIL 5)
PERMANENT VACUUM MONITORING POINT (DETAIL 3)
VAPOR INTRUSION MITIGAITON SYSTEM
LAYOUT - SUB-SLAB
V1
NOTES
1.SEE GENERAL SPECIFICATIONS ON SHEET
V3.
2.DRAWING BACKGROUND FOUNDATION
PLAN PROVIDED BY CLIENT, NO DATE OR
ENGINEER LISTED.
3.THIS VAPOR INTRUSION MITIGATION SYSTEM
DESIGN IS INTENDED TO BE USED FOR
DIRECTION OF VAPOR INTRUSION MITIGATION
SYSTEM COMPONENTS ONLY AND IS NOT
INTENDED TO GUIDE CONSTRUCTION OF
STRUCTURAL COMPONENTS. CONTRACTOR
SHALL VERIFY CONSISTENCY OF DETAILS WITH
APPLICABLE STRUCTURAL, ARCHITECTURAL,
MECHANICAL, AND PLUMBING PLANS AND
RESOLVE INCONSISTENCIES PRIOR TO
INSTALLATION.
4.VIMS COMPONENTS ARE EXAGGERATED FOR
CLARITY.
PJ22017
DH
SCALE: 1/8" = 1'-0"
5/4/2022
VAPOR INTRUSION BARRIER EXTENT (DETAIL 1)
0 5/14/2022 FOR NCDEQ REVIEW DH
TEMPORARY VACUUM MONITORING POINT (DETAIL 7)
1 5/31/2022 REVISIONS TO ADDRESS NCDEQ COMMENTS DH
R-1
R-4
R-3
R-2
VMP-4
VMP-3
VMP-2
VMP-1
TVMP-1
TVMP-2
TVMP-3
TVMP-4
PROJECT
SHEET TITLE
SHEET NO.CLIENTDATE
PROJECT NO.
DRAWN BY
STAMP
REVISION DATE DESCRIPTION ENG
HANLEY ENVIRONMENTAL, PLLC
323 MANNING DRIVE
CHARLOTTE, NORTH CAROLINA 28209
NC LICENSE P-2407
MT. GILEAD COTTON OIL COMPANY
BROWNFIELDS PROPERTY
MT. GILEAD DG LCC
LEGEND
3" SCH 40 PVC SOLID EXHAUST VENT PIPE (DETAIL 5)
PERMANENT VACUUM MONITORING POINT (DETAIL 3)
VAPOR INTRUSION MITIGAITON SYSTEM
LAYOUT - GROUND FLOOR
V2
NOTES
1.SEE GENERAL SPECIFICATIONS ON SHEET
V3.
2.DRAWING BACKGROUNDS FLOOR PLAN
PROVIDED BY NARRAMORE ASSOCIATES,
INC. FLOOR PLAN IS PRELIMINARY, NOT
FINAL.
3.THIS VAPOR INTRUSION MITIGATION SYSTEM
DESIGN IS INTENDED TO BE USED FOR
DIRECTION OF VAPOR INTRUSION MITIGATION
SYSTEM COMPONENTS ONLY AND IS NOT
INTENDED TO GUIDE CONSTRUCTION OF
STRUCTURAL COMPONENTS. CONTRACTOR
SHALL VERIFY CONSISTENCY OF DETAILS WITH
APPLICABLE STRUCTURAL, ARCHITECTURAL,
MECHANICAL, AND PLUMBING PLANS AND
RESOLVE INCONSISTENCIES PRIOR TO
INSTALLATION.
4.VIMS COMPONENTS ARE EXAGGERATED FOR
CLARITY.
PJ22017
DH
SCALE: 1/8" = 1'-0"
5/18/2022
0 5/14/2022 FOR NCDEQ REVIEW DH
TEMPORARY VACUUM MONITORING POINT (DETAIL 7)
1 5/31/2022 REVISIONS TO ADDRESS NCDEQ COMMENTS DH
CONCRETE FLOOR SLAB
GAS PERMEABLE LAYER (NOTE 2)
VAPOR INTRUSION BARRIER (NOTE 1)
SUBBASE
MIN.
4"
CONCRETE FLOOR SLAB
GAS PERMEABLE LAYER (NOTE 2)
VAPOR INTRUSION BARRIER (NOTE 1)
SUBBASE
LOW PROFILE VAPOR COLLECTION SYSTEM (NOTE 3)
1" SCH. 40 PVC
CONCRETE FLOOR SLAB
GAS PERMEABLE LAYER (NOTE 2)
VAPOR BARRIER (NOTE 1)
4-INCH DIAMETER
CLEANOUT WITH
THREADED LID
FLUSH WITH SLAB
PENETRATION SEALED AROUND PIPE (DETAIL 6)
NON-SHRINKING
CEMENT/GROUT
WATERRA 1" ECOPLUG
WITH VAPOUR SAMPLING VALVE
LABEL
MIN. 18"
3-INCH DIAMETER SOLID PVC
EXHAUST VENT PIPING (NOTE 4)
AURA AV-3-PVC PIPE CAP (NOTE 5)
ROOF PENETRATION SEALED
PER MANUFACTURER
RECOMMENDATIONS
LABEL (NOTE 4)
VAPOR BARRIER PENETRATION
SEALED AROUND PIPE (DETAIL6)
LOW PROFILE VAPOR
COLLECTION SYSTEM (NOTE 3)
BRACE EVERY 10' MIN. OR
PER LOCAL CODE
LOW PROFILE VENT TO
PIPE TRANSITION (NOTE 3)
SLAB TURNED DOWN EDGE
OR FOOTING (WIDTH VARIES)
VAPOR INTRUSION BARRIER (NOTE 1)
GAS PERMEABLE LAYER (NOTE 2)
EXTERIOR WALL
EXTEND VAPOR INTRUSION
BARRIER TOP OF CONCRETE
VAPOR INTRUSION BARRIER
CABLE TIEREINFORCEMENT
FABRIC`
NITRA-CORE (60 MIL)
1" SCH. 40 PVC
CONCRETE FLOOR SLAB
GAS PERMEABLE LAYER (NOTE 2)
VAPOR BARRIER (NOTE 1)
PENETRATION SEALED AROUND PIPE (DETAIL 6)
COVER OPENING WITH TAPE
MIN. 12"
PROJECT
SHEET TITLE
SHEET NO.CLIENTDATE
PROJECT NO.
DRAWN BY
STAMP
REVISION DATE DESCRIPTION ENG
V3
GENERAL SPECIFICATIONS
1.VAPOR INTRUSION BARRIER SHALL CONSIST OF MONOSHIELDTM SYSTEM (LAND SCIENCE), INCLUDING A 30-MIL COMPOSITE GEOMEMBRANE SEALED AT SEAMS, PENETRATIONS, AND
TERMINATIONS USING FLUID-APPLIED NITRA-CORETM (LAND SCIENCE). VAPOR INTRUSION BARRIER SHALL BE INSTALLED BY A MANUFACTURER-CERTIFIED INSTALLER IN ACCORDANCE WITH
SPECIFICATIONS INCLUDED IN APPENDIX D.
2.THE GAS PERMEABLE LAYER SHALL CONSIST OF A UNIFORM LAYER OF AT LEAST 4 INCHES IN DEPTH OF WASHED #57 STONE WITH <5% FINES, OR ANOTHER GRAVEL THAT MEETS ASTM C33
REQUIREMENTS FOR SIZE NUMBERS 5, 56, 57, OR 6.
3.VAPOR COLLECTION SYSTEM SHALL CONSIST OF TERRA-VENTTM (LAND SCIENCE) LOW PROFILE VENTING SYSTEM. VAPOR COLLECTION SYSTEM SHALL BE INSTALLED BY A MANUFACTURER-CERTIFIED
INSTALLER IN ACCORDANCE WITH SPECIFICATIONS INCLUDED IN APPENDIX D.
4.EXHAUST VENT PIPES SHALL CONSIST OF 3-INCH DIAMETER PVC PIPING WHICH SHALL PASS THROUGH THE BUILDING SLAB TO THE EXHAUST OUTLET TERMINATIONS ABOVE THE ROOF. PIPING
SHALL BE SECURED IN ACCORDANCE WITH LOCAL BUILDING CODES (10 LINEAR FOOT MINIMUM SPACING) AND LABELED “SOIL GAS” WITH CONTACT INFORMATION FOR QUESTIONS OR REPAIRS AT LEAST
EVERY 10 LINEAR FEET, AND ABOVE THE ROOF. VENT PIPES SHALL RUN STRAIGHT UP TO ROOFTOP. PVC GLUE, PRIMER, AND OTHER MATERIALS USED IN VIMS CONSTRUCTION SHALL NOT CONTAIN
TETRACHLOROETHYLENE (PCE) OR TRICHLOROETHYLENE (TCE).
5.EXHAUST OUTLET TERMINATIONS SHALL BE CAPPED WITH VENT PIPE CAPS (AURA PVC PIPE CAP AV-3-PVC). EXHAUST OUTLETS SHALL BE AT LEAST 18 INCHES ABOVE THE ROOF. EXHAUST OUTLETS
SHALL BE MORE THAN 10 FEET FROM ANY OPENINGS IN STRUCTURES, AIR INTAKES, OR BREATHING SPACES WHERE INDIVIDUALS CONGREGATE OR TRAVERSE.
6.TEMPORARY AND PERMANENT VACUUM MONITORING POINTS (VMPS) SHALL BE INSTALLED PRIOR TO POURING CONCRETE SLAB. VMPS SHALL CONSIST OF 1-INCH DIAMETER SCH-40 PVC
PENETRATING THE VAPOR INTRUSION BARRIER AND ALLOWING FOR AIRFLOW FROM THE GAS PERMEABLE LAYER INTO THE VMP. PERMANENT VMPS SHALL BE CAPPED WITH A 1-INCH ECOPLUGTM WITH
VAPOR SAMPLING VALVE (WATERRA). PERMANENT VMPS SHALL BE PLACED WITHIN A 4-INCH DIAMETER CLEANOUT WITH THREADED LID FLUSH WITH SLAB. TEMPORARY VMPS SHALL EXTEND MINIMUM
12-INCHES ABOVE THE SLAB AND BE COVERED WITH TAPE. TEMPORARY VMPS SHALL BE ABANDONED BY FILLING WITH NON-SHRINKING CEMENT/GROUT AFTER SUCCESSFUL VACUUM EXTENSION
TESTING.
7.CONTRACTOR SHALL SEAL OPENINGS AND PENETRATIONS THROUGH CONCRETE SLABS TO PREVENT AIR LEAKAGE, INCLUDING OPENINGS AROUND PLUMBING, ELECTRICAL CONDUITS, EXHAUST
VENT PIPES, MECHANICAL PIPING, STRUCTURAL SUPPORTS, AND OTHER GAPS. SEALING SHALL BE PERFORMED WITH CAULK THAT COMPLIES WITH ASTM C920 CLASS 25 OR EQUIVALENT. BACKER ROD OR
OTHER COMPARABLE FILLER MATERIAL SHALL BE USED TO SUPPORT CAULK TO SEAL JOINTS OR OPENINGS GREATER THAN ½-INCH IN WIDTH.
8.SYSTEM CONSTRUCTION SHALL BE SUBJECT TO QA/QC INSPECTIONS BY OWNER'S REPRESENTATIVE FOR COMPLIANCE WITH SPECIFICATIONS :
A)SUB-SLAB SYSTEM COMPONENTS (E.G., GAS PERMEABLE LAYER, SOIL GAS INLETS AND PIPING) SHALL PASS INSPECTION PRIOR TO BEING COVERED WITH A VAPOR INTRUSION BARRIER.
B)PLACEMENT OF THE VAPOR INTRUSION BARRIER SHALL PASS INSPECTION BY A MANUFACTURER-CERTIFIED INSPECTOR PRIOR TO POURING THE CONCRETE SLABS. SMOKE TESTING SHALL BE
PERFORMED BY CONTRACTOR IN ACCORDANCE WITH MANUFACTURER RECOMMENDATIONS UNDER OBSERVATION BY INSPECTOR.
C)EXHAUST RISER PIPING SHALL BE INSPECTED PRIOR TO COVERING WITH DRYWALL OR OTHER FINISHINGS.
D)EXHAUST OUTLETS SHALL BE INSPECTED AFTER INSTALLATION.
FINDINGS THAT DO NOT MEET SPECIFICATIONS SHALL BE CORRECTED BY THE CONTRACTOR AND RE-INSPECTED PRIOR TO SYSTEM COMPONENTS BEING COVERED (E.G., BY VAPOR INTRUSION BARRIERS,
CONCRETE SLABS, OR DRYWALL). AT LEAST ONE WEEK NOTICE SHALL BE GIVEN TO INSPECTOR PRIOR TO INSPECTIONS.
9.THIS VIMS DESIGN IS INTENDED TO BE USED FOR DIRECTION OF VAPOR INTRUSION MITIGATION SYSTEM COMPONENTS ONLY AND IS NOT INTENDED TO GUIDE CONSTRUCTION OF STRUCTURAL
COMPONENTS. CONTRACTOR SHALL VERIFY CONSISTENCY OF DETAILS WITH APPLICABLE STRUCTURAL, ARCHITECTURAL, MECHANICAL, AND PLUMBING PLANS AND RESOLVE INCONSISTENCIES PRIOR TO
INSTALLATION.
DH
SCALE: NOT TO SCALE1 VAPOR BARRIER, AND GAS PERMEABLE LAYER
SCALE: NOT TO SCALE3 PERMANENT VACUUM MONITORING POINT
5 EXHAUST VENT RISER AND OUTLET (TYPICAL)
2 PERFORATED SUB-SLAB COLLECTION PIPING SCALE: NOT TO SCALE
SCALE: NOT TO SCALE
SCALE: NOT TO SCALE4 TYPICAL VAPOR INTRUSION BARRIER TERMINATION
HANLEY ENVIRONMENTAL, PLLC
323 MANNING DRIVE
CHARLOTTE, NORTH CAROLINA 28209
NC LICENSE P-2407
0 5/18/2022 FOR NCDEQ REVIEW DH
MT. GILEAD COTTON OIL COMPANY
BROWNFIELDS PROPERTY
MT. GILEAD DG LCC
VAPOR INTRUSION MITIGAITON SYSTEM
DETAILS
PJ22017
5/18/2022
SCALE: NOT TO SCALE6 TYPICAL VAPOR INTRUSION BARRIER PENETRATION SCALE: NOT TO SCALE7 TEMPORARY VACUUM MONITORING POINT
1 5/31/2022 REVISIONS TO ADDRESS NCDEQ COMMENTS DH

APPENDIX D
Vapor Intrusion Barrier and Vapor Collection System
Specifications

Specification Index
Mt. Gilead Cotton Oil Company Brownfields Property
Brownfields Project 25054-21-062

1. MonoShieldTM Specifications
2. TerraVentTM Specifications

1
MonoShield™
Vapor Intrusion Barrier
Geo-Composite &
Fluid Applied Gas
Barrier
Note: If membrane will be subjected to hydrostatic pressure, please contact Land Science™ for proper recommendations.
PART 1 – GENERAL
1.1 RELATED DOCUMENTS A. Drawings and general provisions of the contract apply to this section.
1.2 SUMMARY
A. This section includes the following:
1. Substrate preparation: 2. Vapor intrusion barrier components: 3. Seam sealer and accessories.
1.3 PERFORMANCEREQUIREMENTS A. General: Provide a vapor intrusion barrier system that prevents the passage of volatile organic compound vapors and complies with physical requirements as demonstrated by testing performed by an independent testing agency of manufacturer’s current vapor intrusion barrier formulations and system design.
1.4 SUBMITTALS A. Certified Installer Certificates – Submit certificates signed by manufacturer certifying that installers comply with requirements under the “Quality Assurance” article.
1.5 QUALITY ASSURANCE A. Installer Qualifications: Engage an experienced installer who has been trained and certified in writing by the membrane manufacturer, Land Science™ for the installation of the MonoShield™ System. B. Manufacturer Qualification: Obtain vapor intrusion barrier materials and system components from a single manufacturer source Land Science.
C. Pre-installation Conference: A pre-installation conference call shall be held prior to installation of the venting system
and vapor intrusion barrier to assure proper site and installation conditions, to include contractor, applicator,
engineer and special inspector (if any).
D. The following inspections shall be performed associated with the vapor intrusion barrier.
1. Sub-slab system components (e.g., gas permeable layer, soil gas inlets and piping) will be inspected prior to being
covered with a vapor intrusion barrier.
2. Placement of the vapor intrusion barrier will be inspected prior to pouring the concrete slabs.
3. Smoke testing will be performed in accordance with vapor intrusion barrier manufacturer requirements.
Findings that do not meet specifications will be re-inspected following correction. Installer shall provide notification at least one week prior to inspections.
2

1.6 DELIVERY, STORAGE, AND HANDLING
A. Deliver materials to project site as specified by manufacturer labeled with manufacturer’s name, product brand
name and type, date of manufacture, shelf life, and directions for storing and mixing with other components.
B. Store materials as specified by the manufacturer in a clean, dry, protected location and within the temperature
range required by manufacturer. Protect stored materials from direct sunlight. If freezing temperatures are
expected, necessary steps should be taken to prevent the freezing of the Nitra-Core and Nitra-Core Detail
components.
C. Remove and replace material that cannot be applied within its stated shelf life.
1.7 PROJECT CONDITIONS
A. Protect all adjacent areas not to be installed on. Where necessary, apply masking to prevent staining of
surfaces to remain exposed wherever membrane abuts to other finish surfaces. B. Perform work only when existing and forecasted weather conditions are within manufacturer’s recommendations for the material and application method used. C. Minimum clearance of 24 inches is required for application of product. For areas with less than 24-inch clearance, the membrane may be applied by hand using Nitra-Core Detail. D. Ambient temperature shall be within manufacturer’s specifications. (Greater than +45ºF/+7ºC.) Consult manufacturer for the proper requirements when desiring to apply Nitra-Core below 45ºF/7ºC. E. All plumbing, electrical, mechanical and structural items to be under or passing through the vapor intrusion barrier system shall be positively secured in their proper positions and appropriately protected prior to membrane application. F. Vapor intrusion barrier shall be installed before placement of fill material and reinforcing steel. When not possible, all exposed reinforcing steel shall be masked by general contractor prior to membrane application.
G. Stakes used to secure the concrete forms shall not penetrate the vapor intrusion barrier system after it has been
installed. If stakes need to puncture the vapor intrusion barrier system after it has been installed, the necessary
repairs need to be made by a certified MonoShield applicator. To confirm the staking procedure is in agreement
with the manufactures recommendation, contact Land Science. 1.8 WARRANTY A. General Warranty: The special warranty specified in this article shall not deprive the owner of other rights the owner
may have under other provisions of the contract documents, and shall be in addition to, and run concurrent with,
other warranties made by the contractor under requirements of the contract documents.
B. Special Warranty: Submit a written warranty signed by vapor intrusion barrier manufacturer agreeing to repair or
replace vapor intrusion barrier that does not meet requirements. Warranty does not include failure of vapor
intrusion barrier due to failure of substrate prepared and treated according to requirements or formation of
new joints and cracks in the attached to structures that exceed 1/16 inch (1.58 mm) in width.
1. Warranty Period: 1 year after date of substantial completion. Longer warranty periods are available upon
request to the manufacturer.
C. Extended material warranties are available upon request to the manufacturer.
PART 2 – PRODUCTS
2.1 MANUFACTURERS
A. MonoShield™ System; Land Science™, San Clemente, CA. [phone]
1. MonoBase Layer
2. Nitra-Core layer and Nitra-Core Detail
3

2.2 VAPOR INTRUSION BARRIER SHEET MATERIALS A. The MonoShield™ System is a 30-mil composite geomembrane comprise of flexible chemically resistant
metalized film laminated to a geotextile, a copolymer polyethylene and tear resistant PET reinforcement grid
structure.
B. Sheet Course Usage
1. As foundation base layer, made to receive the Nitra-Core layer between seams.

MonoBase Properties

PROPERTIES TEST METHOD MonoBase

Composite Thickness MFX internal Method 30 mil
Layer Thickness MFX internal Method 22 mil
Weight EN1849-2 13 oz./SY
Colors Metallic Gray/Black
Geotextile Tensile Strength (Grab) ASTM D751 - Procedure A MD – 236 lbs.
CD – 247 lbs.
Elongation ASTM D751 – Procedure A MD – 81%
CD – 20%
Tear Resistance ASTM D5884 MD – 26 lbs.
CD – 30 lbs.
Fire Properties EN13501-1 Class F UV Stability 6 Months Free Outdoor Exposure
Methane Permeability ASTM D1434 <11 (mL(STP)/m2.d.atm)
Benzene Diffusion Coefficient GeoKinetics Method 2.1 x 10-18 m2/sec
TCE Diffusion Coefficient GeoKinetics Method 2.89 x 10-17 m2/sec
Chemical Resistance Excellent
Packaging: Dimension: 9.84’ x 164’ Weight: 143 lbs.

2.3 VAPOR INTRUSION BARRIER SPRAY MATERIALS A. Fluid applied vapor intrusion barrier system – Nitra-Core; a single course, high build, polymer modified, nitrile latex
and asphalt emulsions. Waterborne and spray applied at ambient temperatures. A nominal thickness of 60 dry mils
between MonoBase seams, unless specified otherwise. Non-toxic and odorless, Nitra-Core Detail has similar
properties with greater viscosity and is roller or brush applied. Manufactured by Land Science.

4

Nitra-Core Properties
PROPERTIES TEST METHOD NITRA-CORE
Application to MonoBase 60 mils (17 ft2/gal) at
seams
Typical Uncured Properties
Specific Gravity ASTM D 244 1.0
Brookfield Viscosity ASTM D2196 75 – 90 centipoises
pH Oakton 10 – 13
Residue Content ASTM D2939 62 – 65%
Color Brown to Black
Demulsibility ASTM D6936 35 – 40%
Non-Toxic No Solvent
Shelf Life 6 months

Typical Cured Properties
with
MonoBase

Benzene Diffusion Coefficient GeoKinetics Method 2.1 x 10-18 m2/sec
TCE Diffusion Coefficient GeoKinetics Method 2.89 x 10-17 m2/sec
Methane Permeability ASTM D1434 <11 (mL(STP)/m2.d.atm)
Packaging: 55 gal. drums and 275 gal. totes
2.4 AXILLARY MATERIALS
A. Sheet Flashing: 60-mil reinforced modified asphalt sheet good with double-sided adhesive. B.
Detailing Fabric: Manufacturer’s recommended polypropylene and polyester fabric.
C. Gas Venting Materials: TerraVent and associated fittings. PART
3 – EXECUTION
3.1 AUXILIARY MATERIALS A. Examine substrates, areas, and conditions under which vapor intrusion barrier will be applied, with installer present, for compliance with requirements. Do not proceed with installation until unsatisfactory conditions have been corrected.
3.2 SUBGRADE SURFACE PREPARATION
A. Verify substrate is prepared according to manufacturer’s recommendations. On a horizontal surface, the substrate
should be free from material that can potentially puncture the vapor intrusion barrier. Additional protection or
cushion layers might be required if the earth or gravel substrate contains too many jagged points and edges that
could puncture one or more of the system components. Contact manufacturer to confirm substrate is within
manufactures recommendations. B. MonoShield™ System can accommodate a wide range of substrates, including but not limited to compacted earth, sand, aggregate, and mud slabs. 1. Compacted Earth: Remove pieces of debris, gravel and/or any other material that can potentially puncture the MonoBase prior to application.
2. Sand: A sand subgrade requires no additional preparation, provided any material that can potentially
puncture MonoBase not present.
5

3. Aggregate: Contact the manufacturer to ensure the aggregate layer will not be detrimental to the
MonoBase. The gravel layer must be compacted and rolled flat. Ideally a ¼” minus gravel layer with
rounded edges should be specified; however MonoBase can accommodate a wide variety of different
substrates. Contact Land Science if there are questions regarding the compatibility of MonoBase and the
utilized substrate. Exercise caution when specifying pea gravel under the membrane, if not compacted
properly, pea gravel can become an unstable substrate. NOTE: Angular substrates will likely require the
use of a 4 oz. geotextile cushion layer, contact Land Science for additional information.
4. Mudslabs: The use of a mubslab under the MonoBase is acceptable, contact Land Science for job specific
requirements.
C. Mask off adjoining surface not receiving the vapor intrusion barrier system to prevent the spillage or over spray affecting other construction.
D. Earth, sand or gravel subgrades should be prepared and compacted to local building code requirements.
3.3 PREPARATIONS AND TREATMENT OF TERMINATIONS A. Prepare the substrate surface in accordance with Section 3.3 of this document. Concrete surfaces that are not a light trowel, light broom or equivalent finish, will need to be repaired. B. Terminations on horizontal and vertical surfaces should extend 6” onto the termination surface. Job specific conditions may prevent a 6” termination. In these conditions, contact manufacturer for recommendations.
C. Apply 60 mils of Nitra-Core to the terminating surface and then embed the MonoBase by pressing it firmly into the Nitra-
Core layer. Next, apply 30 mils of Nitra-Core spray applied on MonoBase over the edge of the termination. For further
clarification, refer to the termination detail provided by manufacturer.
D. The stated termination process is appropriate for terminating the membrane onto exterior footings, pile caps, interior
footings and grade beams. When terminating the membrane to stem walls or vertical surfaces the same process
should be used.
3.4 PREPARATIONS AND TREATMENT OF PENETRATIONS
A. All pipe penetrations should be securely in place prior to the installation of the MonoBase. Any loose penetrations should
be secured prior to MonoBase, as loose penetrations could potentially exert pressure on the membrane and damage the
membrane after installation. B. To properly seal around penetrations, cut a piece of the MonoBase that will extend 6” beyond the outside perimeter of
the penetration. Cut a hole in the MonoBase just big enough to slide over the penetration, ensuring the MonoBase fits
snug against the penetration, this can be done by cutting an “X” no larger than the inside diameter of the penetration.
There should not be a gap larger than a 1/8” between the MonoBase and the penetration. Other methods can also be
utilized, provided, there is not a gap larger than 1/8” between the MonoBase and the penetration.
C. Seal the MonoBase using Nitra-Core spray applied or Nitra-Core Detail to the underlying cut piece of MonoBase.
D. Apply one coat of Nitra-Core spray or Nitra-Core Detail to the MonoBase and around the penetration at a thickness
of 30 mils. Penetrations should be treated in a 6-inch radius around penetration and 3 inches onto penetrating
object.
E. Embed a Detail Fabric strip after the first application of the Nitra-Core spray applied or Nitra-Core Detail material
and then apply a second 30 mil coat over the embedded joint reinforcing strip ensuring its complete saturation
of the embedded strip and tight seal around the penetration. F. A cable tie should then be placed around the finished penetration. The cable tie should be snug, but not overly tight so as to slice into the finished seal. OPTION: A final application of Nitra-Core spray may be used to provide a finishing seal after the protective layer has been installed. NOTE: Metal or other slick penetration surfaces may require treatment in order to achieve proper adhesion. For plastic pipes, sand paper may be used to achieve a profile, an emery cloth is more appropriate for metal surfaces. An emery cloth should also be used to remove any rust on metal surfaces.
6

3.5 MONOBASE INSTALLATION A. Install the MonoBase over substrate material in one direction with six-inch overlaps.
B. Secure the MonoBase layer by applying 60 mils of Nitra-Core tween the 6” overlapped sheets. C.
Visually verify there are no gaps/fish-mouths in seams.
D. For best results, install an equal amount of MonoBase and Nitra-Core in one day. Leaving the MonoBase unsprayed overnight might allow excess moisture to collect on the MonoBase. If excess moisture collects, it needs to be removed.
NOTE: In windy conditions it might be necessary to encapsulate the seam by spraying the Nitra-Core layer over the
completed MonoBase seams. 3.6 NITRA-CORE APPLICATION
A. Set up spray equipment according to manufacturer’s instructions.
B. Mix and prepare materials according to manufacturer’s instructions.
C. The two catalyst nozzles (8001) should be adjusted to cross at about 18" from the end of the wand. This apex of catalyst
and emulsion spray should then be less than 24" but greater than 12” from the desired surface when spraying. When
properly sprayed the fan pattern of the catalyst should range between 65° and 80°.
D. Adjust the amount of catalyst used based on the ambient air temperature and surface temperature of the
substrate receiving the membrane. In hot weather use less catalyst as hot conditions will quickly “break” the
emulsion and facilitate the curing of the membrane. In cold conditions and on vertical surfaces use more catalyst
to “break” the emulsion quicker to expedite curing and set up time in cold conditions.
E. To spray Nitra-Core layer, pull the trigger on the gun. A 42° fan pattern should form when properly sprayed. Apply one
spray coat of Nitra-Core to obtain a seamless membrane free from pinholes or shadows, with an average dry film
thickness of 60 mils (1.52 mm).
F. Apply the Nitra-Core layer in a spray pattern that is perpendicular to the application surface. The concern when spraying
at an angle is that an area might be missed. Using a perpendicular spray pattern will limit voids and thin spots and will
also create a uniform and consistent membrane.
G. The seams will generally cure in 24 to 48 hours. As a rule, when temperature decreases or humidity increases, the
curing of the membrane will be prolonged. The membrane does not need to be fully cured prior to smoke test.
H. Do not penetrate membrane after it has been installed. If membrane is penetrated after the membrane is
installed, it is the responsibility of the general contractor to notify the certified installer to make repairs.
I. Conducting smoke tests on the barrier is recommended with general emphasis towards the seams, penetrations, and perimeter terminations. Land Science recommends conducting smoke tests every 5,000-10,000 square feet or a minimum of two per building structure (if less than 5,000 square feet in size). The square footage for testing can be increased upon successful smoke tests conducted initially at a 5,000 square foot area.
NOTE: Care should be taken to not trap moisture between the layers of the membrane. Trapping moisture may occur from applying a second coat prior to the membrane curing. Repairs and detailing may be done over the Nitra- Core layer when not fully cured.
3.7 QUALITY ASSURANCE A. The MonoShield™ system must be installed by a trained and certified installer approved by Land Science.
B. For projects that will require a material or labor material warranty, Land Science will require a manufacturer’s
representative or certified 3rd party inspector to inspect and verify that the membrane has been installed per the
manufacturer’s recommendations.
The certified installer is responsible for contacting the inspector for inspection. Prior to application of the membrane, a notice period for inspection should be agreed upon between the applicator and inspector.
7

C. Smoke Testing is highly recommended and is the ideal way to test the seal created around penetrations and
terminations. Smoke Testing is conducted by pumping non-toxic smoke underneath the MonoShield™ system and
then repairing the areas where smoke appears. Refer to smoke testing protocol provided by Land Science. For
projects that will require an extended material warranty, Land Science will require a smoke test. D. Visual inspections prior to placement of concrete, but after the installation of concrete reinforcing, is recommended
to identify any punctures that may have occurred during the installation of rebar, post tension cables, etc. Punctures
in the MonoShield™ system should be easy to identify due to the color contrasting layers of the system.
1
TerraVent™
SOIL GAS COLLECTION SYSTEM

PART 1 – GENERAL
1.1 RELATED DOCUMENTS

A. Drawings and general provisions of the contract apply to this Section.

1.2 SUMMARY

A. This Section includes the following:

1. Substrate preparation.
2. TerraVent™ installation.
3. TerraVent accessories.

1.3 PERFORMANCEREQUIREMENTS

A. General: Provide a gas venting material that collects gas vapors and directs them to discharge or to collection points as specified
in the VIMS Design drawings and complies with the physical requirements set forth by the manufacturer.

1.4 SUBMITTALS
A. Certified Installer Certificates – Submit certificates signed by manufacturer certifying that installers comply with requirements under the “Quality Assurance” article.

1.5 QUALITY ASSURANCE

A. Installer Qualifications: Engage an experienced Installer who is certified in writing and approved by vapor intrusion barrier
manufacturer Land Science for the installation of the TerraShield and Nitra-Seal vapor intrusion barrier system.
B. Manufacturer Qualification: Obtain gas venting, vapor intrusion barrier and system components from a single manufacturer Land Science.
C. Pre-installation Conference: A pre-installation conference call shall be held prior to installation of the venting system and vapor
intrusion barrier to assure proper site and installation conditions, to include contractor, applicator, engineer and special
inspector (if any).

D. The following inspections shall be performed associated with the vapor intrusion barrier.
1. Sub-slab system components (e.g., gas permeable layer, soil gas inlets and piping) will be inspected prior to being covered
with a vapor intrusion barrier.
2. Placement of the vapor intrusion barrier will be inspected prior to pouring the concrete slabs.
3. Smoke testing will be performed in accordance with vapor intrusion barrier manufacturer requirements.
Findings that do not meet specifications will be re-inspected following correction. Installer shall provide notification at least one week prior to inspections.
1.6 DELIVERY, STORAGE, AND HANDLING

A. Deliver materials to project site as specified by manufacturer labeled with manufacturer’s name, product brand name and type,
date of manufacture, shelf life, and directions for handling.
2
B. Store materials as specified by the manufacturer in a clean, dry, protected location and within the temperature range required by manufacturer. Protect stored materials from direct sunlight.
C. Remove and replace material that is damaged.
PART 2 – PRODUCTS
2.1 MANUFACTURER

A. Land Science, San Clemente, CA. [phone]

1. TerraVent™

2.2 GAS VENT MATERIALS

A. TerraVent – TerraVent is a low profile, trenchless, flexible, sub slab vapor collection system used in lieu or in conjunction
with perforated piping. TerraVent is recommended for sites with methane gas and aggressive chlorinated volatile organic or
petroleum vapors. Manufactured by Land Science.

B. TerraVent physical properties
PROPERTIES TEST METHOD TerraVent

Vent Core Properties
Compressive Strength ASTM D-1621 9,500 psf.
Thickness 1 inch
Flow Rate (Hydraulic gradient = 0.1) ASTM D-4716 30 gpm/ft width

Vent Fabric Properties
Grab Tensile Strength ASTM D-4632 100 lbs.
CBR Puncture ASTM D-6241 250 lbs.
Flow ASTM D-4491 140 gpm/ft2
AOS ASTM D-4751 70 U.S Sieve
Permittivity ASTM D-4491 2.0 sec-1
U.V Resistance ASTM D-4355 70% @500 hrs.
Packaging: Dimension: 12”x 165’
Weight: 68 lbs.

2.3 AUXILIARY MATERIALS

A. TerraVent End Out

B. Reinforced Tape.
PART 3 – EXECUTION
3.1 EXAMINATION

A. Examine substrates, areas, and conditions under which gas vent system will be installed, with installer present, for
compliance with requirements. Do not proceed with installation until unsatisfactory conditions have been corrected.

3.2 SUBSTRATE PREPARATION

A. Verify substrate is prepared according to project requirements.
3
3.3 PREPARATION FOR STRIP COMPOSITE

A. Mark the layout of strip geocomposite per VIMS Design drawings.

3.4 STRIP GEOCOMPOSITE INSTALLATION

A. Install TerraVent over substrate material where designated on drawings with the flat base of the core placed up and shall be
overlapped in accordance with manufacturer’s recommendations.

B. At areas where TerraVent strips intersect cut and fold back fabric to expose the dimpled core. Arrange the strips so that the
top strip interconnects into the bottom strip. Unfold fabric to cover the core and use reinforcing tape, as approved by the
manufacturer, to seal the connection to prevent sand or gravel from entering the core.

C. When crossing TerraVent over footings or grade beams, consult with the specifying environmental engineer and
structural engineer for appropriate use and placement of solid pipe materials. Place solid pipe over or through concrete
surface and attach a TerraVent End Out at both ends of the pipe before connecting the TerraVent to the pipe reducer. Seal the
TerraVent to the TerraVent End Out using fabric reinforcement tape. Refer to TerraVent detail provided by Land Science.

D. Place vent risers per VIMS Design drawings. Connect TerraVent to TerraVent End Out and seal with fabric reinforced tape. Use
TerraVent End Out with the specified diameter piping as shown on system drawings.

3.5 PLACEMENT OF OVERLYING AND ADJACENT MATERIALS
A. All overlying and adjacent material shall be placed or installed using approved procedures and guidelines to prevent damage to the strip geocomposite.
B. Equipment shall not be directly driven over and stakes or any other materials may not be driven through the strip
geocomposite.

APPENDIX E
TO-15 Analyte List
TO-15 Analyte List
Mt. Gilead Cotton Oil Company Brownfields Property
Brownfields Project 25054-21-062

Future analyses of soil gas or indoor air at the proposed site building will be analyzed for
the following compounds previously detected in site soil gas, groundwater, or soil:
Acetone
Benzene
2-Butanone (MEK)
Carbon Disulfide
Carbon tetrachloride
Chloroform
Chloromethane
Cis-1,2-dichlorethylene
Dichlorodifluoromethane (Freon 12)
Ethanol
Ethylbenzene
4-Ethyltoluene
Heptane
Hexane
4-Methyl-2-pentanone (MIBK)
Styrene
Tetrachloroethylene
Tetrahydrofuran
Toluene
Trans-1,2-dichlorethylene
Trichloroethylene
1,2,4-Trimethylbenzene
1,3,5-Trimethylbenzene
m-Xylene
p-Xylene
o-Xylene
Vinyl chloride