20593_N Mangum St_WP_20220608

S&ME, Inc. | 3201 Spring Forest Road | Raleigh, NC 27616 | p 919.872.2660 | www.smeinc.com
June 8, 2022
North Carolina Department of Environmental Quality
Division of Waste Management, Brownfields Program
217 West Jones Street
Raleigh, North Carolina 27605
Attention: Ms. Sharon Eckhard via email: [e-mail]
Brownfields Project Manager
Reference: Assessment Work Plan for Soil, Soil Gas, and Groundwater
601 N. Mangum Street, Durham, North Carolina
Brownfields Project Name: N. Mangum St. Properties II
Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
Dear Ms. Eckhart:
S&ME, Inc. (S&ME) on behalf of our client, Mangum Street Partners, LLC, is submitting this Work Plan to conduct
assessment activities at the above referenced site. Mangum Street Partners, LLC 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, soil gas, and groundwater samples from selected areas to support development design
and considerations regarding possible exposures and environmental management of 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.
Michael W. Pfeifer Samuel P. Watts, PG
Senior Project Manager Principal Geologist
[e-mail] [e-mail]
Enclosure: Work Plan for Soil, Soil Gas, and Groundwater Assessment, dated June 8, 2022
cc: Shirley Liggins ([e-mail]) – NC Brownfields Program
John Sunter ([e-mail]) - Mangum Street Partners, LLC
Assessment Work Plan
for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum St. Properties II
Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
PREPARED FOR:
Mangum St. Partners, LLC
c/o Four Points Development, LLC
1805 7th Street, NW
Washington, DC 20001
PREPARED BY:
S&ME, Inc.
3201 Spring Forest Road
Raleigh, NC 27616
Corporate Registration for Licensing of NC Geologists No. C-145
NC Engineering Firm No. F-0176
June 8, 2022
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 1
Table of Contents
CERTIFICATION......................................................................................................................................................... ii
1.0 Introduction ....................................................................................................................... 2
2.0 Scope of Work .................................................................................................................... 4
2.1 Basis and Approach ....................................................................................................................... 4
2.2 Project Management, Health and Safety Plan, and Coordination ........................................... 4
2.3 Schedule ........................................................................................................................................... 4
3.0 Sampling Methodology ................................................................................................... 5
3.1 Soil Gas Sampling ........................................................................................................................... 5
3.1.1 Sample Locations ............................................................................................................................... 5
3.1.2 SGI Sampling Train Setup and Helium Leak Test Methodology ..................................................... 6
3.1.3 Soil Gas Sampling Methodology ....................................................................................................... 8
3.2 Groundwater Sampling ................................................................................................................. 9
3.3 Soil Sampling ................................................................................................................................ 10
4.0 Laboratory Analysis ........................................................................................................ 10
5.0 Quality Assurance/Quality Control ............................................................................ 10
5.1 Field and Laboratory Control Duplicates ................................................................................. 10
5.2 Sampling Equipment ................................................................................................................... 11
5.3 Sample Custody ............................................................................................................................ 11
5.4 Laboratory Analytical Report ..................................................................................................... 11
6.0 Investigative Derived Waste (IDW) Management and Disposal .......................... 11
7.0 Reporting .......................................................................................................................... 12
8.0 References ......................................................................................................................... 12
List of Attachments
Figure 1 – Site Topographic Map
Figure 2 – Sample Location Map
Figure 3 – Historical Sample Location Map
Figure 4 – Site Grading Plan
Table 1 – Sample Point Information
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 2
1.0 Introduction
S&ME, Inc. (S&ME) on behalf of our client, Mangum Street Partners, is submitting this Work Plan to conduct soil,
soil gas, and groundwater assessment activities at the Brownfields Project Site: Greenhouse Project/Mangum
Street Properties II (Brownfields Project No.: 20593-21-032). Mangum Street Properties intends to develop the
Site under the North Carolina Department of Environmental Quality (NCDEQ) Brownfields Program (NCBP). The
referenced property is west of North Mangum Street, south of Broadway Street and north of Hunt Street in
Durham, Durham County, North Carolina and is owned by Mangum Street Partners, LLC. A site vicinity map is
provided as Figure 1 and a site map showing proposed sampling locations is provided as Figure 2. The property
consists of 10 property parcels, totaling approximately 1.52 acres:
Durham County Parcel ID Property Address Acreage
104952 110 Hunt Street 0.15
104951 108 Hunt Street 0.114
104953 106 Hunt Street 0.148
104594 601 N. Mangum Street 0.188
104955 603 N. Mangum Street 0.233
104956 605 N. Mangum Street 0.161
104957 607 N. Mangum Street 0.127
104958 103 Broadway Street 0.073
104959 107 Broadway Street 0.153
104960 109 Broadway Street 0.173
Based on prior environmental reports prepared by others, the site was historically developed with residential
structures, beginning in 1913. An auto repair shop and gasoline filling station with two underground storage tanks
(USTs) were formerly present on the northeast corner of the site (607 N. Mangum Street). The UST system was
reportedly removed from the site in 1988, and approximately 50 cubic yards of petroleum-impacted soils were
spread on the ground surface near the center of the site at a thickness of approximately 0.5 to one foot. The
laboratory analytical results of three soil samples (labeled as HA-3,9, HA-4,8, and HA-6,4) collected on June 14,
1989 indicated that total petroleum hydrocarbons (TPH) gasoline range organics (GRO) was detected below the
North Carolina Action Level (at that time) of 10 parts per million (PPM) in HA-3,9 and HA-6,4. TPH-GRO was not
detected in sample HA-4,8.
In addition, one groundwater sample was collected (labeled as HA-6W) and analyzed for volatile organic
compounds (VOCs). The laboratory analytical results of this sample indicated that benzene was detected at a
concentration of 48 micrograms per liter (µg/L), exceeding the North Carolina Groundwater 2L Standard (2L
Standard) of 1 µg/L. Several other targeted contaminant constituents were detected in concentrations exceeding
their laboratory detection limits, but below their respective 2L Standards.
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 3
It is unclear from the documentation available to S&ME where these soil and groundwater samples were
collected, however, it is likely that they were collected within the former UST basin on the northeastern corner of
the site.
At the request of the North Carolina Department of Environment, Health, and Natural Resources, two additional
soil samples (labeled as HB-1 and HB-2 – depths unknown) were collected in the area of the former UST
excavation on August 2, 1989. The laboratory analytical results of the soil samples indicated TPH-GRO were not
present in concentrations above the laboratory’s detection limits.
One groundwater monitor well (MW-1) was apparently installed within the former UST area in August 1989, and
subsequently sampled. The laboratory analytical results of the groundwater sample collected from the well
reported the following compounds typically associated with petroleum contamination: benzene (735 µg/L),
toluene (155.2 µg/L), chlorobenzene (6.8 µg/L), ethylbenzene (53.7 µg/L), 1,3-dichlorobenzene (50.0 µg/L), 1,4-
dichlorobenzene (29.9 µg/L), and 1,2-dichlorobenzene (15.0 µg/L). The incident (No. 3788) was closed by the
North Carolina Department of Environment and Natural Resources (NCDENR) in 1989. Piedmont Geologic, P.C.
resampled this monitoring well in 2007 and the sample exhibited petroleum constituents and chlorinated
compounds at concentrations that exceeded the 2L standards. However, NCDEQ issued a second No Further
Action letter on April 23, 2007. The monitor well was reportedly grouted by the City of Durham sometime in 2007.
In May 2021, S&ME conducted a Geotechnical Exploration at the site, consisting of installing eight geotechnical
soil borings across the site. Due to the potential for encountering contaminated soils, S&ME environmental
personnel were also present during the installation of the soil borings to monitor VOCs in the soil cuttings utilizing
a hand-held photo-ionization detector (PID). Elevated readings on the PID were encountered in two of the soil
borings (B-2 and B-5). Petroleum odors were noted in B-2 (located on the northeastern portion of the site) from
approximately six feet below ground surface continuing to the boring termination depth of 39 feet below ground
surface. The PID measurements from B-2 ranged from 77.6 parts per million (ppm) at a depth of approximately
8.5 feet to 4.5 ppm at a depth of approximately 23.5 feet. The PID measurements collected from boring B-5
(located on the eastern portion of the site) ranged from 412 ppm at a depth of approximately 3.5 feet to 1.4 ppm
at a depth of approximately 33.5 feet.
Section 8.0 in this Work Plan includes a list of assessment reports, relevant to the Greenhouse Project/N. Mangum
St. Properties II Site, which were considered in preparing this assessment work plan. Figure 3 depicts locations of
previous soil and groundwater sample locations over the assessment history of the site.
We understand that parking will occupy the lower three levels of the structure. The current site elevations range
from approximately 396 feet above mean sea level (AMSL) on the northern portion of the site to approximately
382 feet AMSL on the southern portion of the site. Based on information previously provided to S&ME, the
elevation of the foundations is expected to be approximately 377 feet AMSL, with the average grade at each
building corner at 389 feet AMSL.
A preliminary site grading plan, indicating the cut/fill areas is included as Figure 4.
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 4
2.0 Scope of Work
2.1 Basis and Approach
As indicated previously, Mangum Street Partners is constructing an eight-story structure, consisting of parking,
retail, and residential components A such, S&ME is proposing to conduct soil, soil gas, and groundwater sampling
within the proposed structure footprint. The results of the soil gas investigation will be used to determine the
need for a vapor mitigation system below the proposed structure. The results of the soil and groundwater
investigation will be used to assess the absence of contaminants of concern in the soil and groundwater across
the site and/or identify areas that may require impacted media management during 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 2022). 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. Figure 2 shows the proposed locations of soil, soil gas and groundwater locations.
Soil Sampling – S&ME will collect three soil samples from the northeastern portion of the site during this
assessment. In addition, soil samples will be collected during the installation of the borings for the groundwater
monitor wells and soil gas samples (additional 12 soil samples).
Groundwater Sampling – S&ME will collect four groundwater samples during this assessment. The groundwater
sampling locations have been selected to address areas of concern and/or fill in analytical data gaps for the
groundwater across the site.
Soil Gas Assessment – S&ME will collect eight soil gas samples during this assessment. The soil gas sampling
locations have been selected to widely cover the site. The results of the soil gas assessment will be used to
determine the need for a vapor mitigation system beneath the proposed structure.
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:
Prepare 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
groundwater and soil vapor samples are to be collected.
2.3 Schedule
The field assessment activities are planned to begin in June 2022 (pending NCDEQ approval of this Work Plan)
and will be completed within approximately three weeks. S&ME anticipates submitting a draft summary of
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 5
findings approximately one week after receipt of final laboratory results. The general site assessment schedule is
presented below.
Site Assessment Schedule
Task Duration
Project Management, Health and Safety Plan, and Coordination As Needed
Elevation Survey, Groundwater and Soil Gas Sampling 1 week
Laboratory Analysis 2 weeks
Prepare Additional Groundwater and Soil Gas Assessment Report 2 weeks
3.0 Sampling Methodology
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)
3.1 Soil Gas Sampling
3.1.1 Sample Locations
S&ME proposes to install up to eight soil gas implants (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 soil gas implants (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(s) of the proposed structure. The targeted depth of
each of the SGIs will be approximately 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 the attached 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
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 6
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 PID for the presence of volatile
organic compounds (VOCs). The soil samples will be screened in approximate two-foot increments utilizing VOC-
free media.
3.1.2 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
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.
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 7
The photograph below is an example of the sampling array during a leak test.
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.
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 8
3.1.3 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. During the sampling event, S&ME will record the temperature, wind speed, weather conditions,
and barometric pressure that are recorded at the Raleigh-Durham International Airport weather station via the
National Oceanic and Atmospheric Administration website.
Once the soil gas samples are collected, the samples will be shipped under standard chain-of-custody protocol to
a North Carolina certified laboratory for analysis of VOCs (including naphthalene) by EPA Method TO-15. 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.
Upon approval from the NCDEQ Brownfields Program, S&ME will properly abandon the void created by the
Geoprobe® rods with hydrated bentonite clay mix. The disturbed surface material will be restored to the condition
it was prior to the subsurface probe/drilling.
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 9
3.2 Groundwater Sampling
S&ME proposes to install four temporary wells for the collection of groundwater samples, to evaluate
groundwater quality and elevations in the building footprint. S&ME will use a track-mounted Geoprobe® drill rig
with direct push technology to install the three temporary groundwater wells for the collection of groundwater
samples at the locations shown on the attached Figure 2. According to S&ME’s Geotechnical Exploration Report,
dated June 9, 2021, groundwater was encountered in several geotechnical borings at depths of 1.5 to 14 ft-bgs.
We assume a maximum drilling depth of 20 ft-bgs for installing the monitor wells. See the attached Table 1 for
the planned depths of the groundwater samples.
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 volatile organic compounds (VOCs). The soil samples will be screened in approximate two-
foot increments.
After reaching termination depths in each of the soil borings, the temporary wells will be constructed by installing
a 10-foot section of one-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.
S&ME will measure the depth to groundwater using 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 temporary sampling points, S&ME will purge each temporary
well using a submersible peristaltic pump with new dedicated Teflon-lined tubing in each temporary well. The
tubing depth will be selected to intersect the well screen in each temporary well. Prior to collecting samples for
laboratory analysis, S&ME will measure field parameters consisting of pH, temperature, specific conductivity,
dissolved oxygen, and turbidity after each volume of groundwater is purged, or until the temporary well runs dry.
The groundwater samples will be collected utilizing low-flow techniques when the pH remains constant within 0.1
standard unit and the specific conductance varies no more than 5%. The purge parameters will be recorded on
field collection sheets and will also be tabulated in the report.
Groundwater pumped from the temporary 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 8260B, for semi-volatile organic compounds (SVOCs) by EPA Method 8270, and for RCRA 8
Metals by Method 6010 and for hexavalent chromium by Method 7196. One blind duplicate sample will be
collected and analyzed for the same parameters as the record samples.
After the groundwater samples are collected, S&ME will properly abandon temporary wells in general accordance
with 15 NCAC Subchapter 2C Rule .0113 Abandonment of Wells, by removing the PVC casing, and filling the
borehole void with hydrated bentonite clay mix. The disturbed surface material will be restored to the condition it
was prior to the subsurface probe/drilling.
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 10
3.3 Soil Sampling
During the installation of the groundwater and soil gas samples, S&ME will collect soil samples in approximate
two-foot intervals. In addition to the samples collected from groundwater and soil gas borings, three additional
soil samples will be collected at locations shown on Figure 2. The soil samples will be continuously collected in
five-foot long disposable acetate-plastic sleeves that line the hollow stainless-steel sample probes that are
advanced by the Geoprobe®. The soil from each boring will be visually classified by S&ME personnel and field-
screened with a PID for the presence of VOCs. The section of soil exhibiting the highest PID reading of VOCs will
be collected for laboratory analysis. Additionally, if there are indications of contamination (staining, odors), S&ME
will collect a sample from that interval. If the PID does not reveal the presence of VOCs, and if there are no
physical indications of contamination, S&ME will collect the soil sample at the depth closest to the groundwater
table for laboratory analysis.
The soil samples will be placed into laboratory-supplied containers, stored in an ice-filled cooler, and shipped
under chain of custody to a North Carolina certified laboratory. The soil samples will be analyzed for VOCs by EPA
Method 8260B, for semi-volatile organic compounds (SVOCs) by Method 8270, for the RCRA 8 Metals by EPA
Method 6010, and for hexavalent chromium by EPA Method 3060A/7196A.
4.0 Laboratory Analysis
As noted above, the media samples will be analyzed as summarized below:
Soil gas samples - VOCs, including naphthalene, by EPA Method TO-15.
Groundwater samples - VOCs by EPA Method 8260, SVOCs by EPA Method 8270/625, 8 RCRA Metals by
EPA Method 6010/7470, and hexavalent chromium by Method 7196.
Soil samples - VOCs by EPA Method 8260, for SVOCs by EPA Method 8270/625, for the RCRA 8 Metals by
EPA Method 6010, and for hexavalent chromium by Method 7196.
Samples will be submitted under standard chain-of-custody procedures to a North Carolina 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
One additional co-located, blind duplicate quality assurance/quality control (QA/QC) sample will also be collected
during soil gas and groundwater 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.
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 11
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 temporary 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
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 (COC) 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 COC. If the samples are
shipped using a commercial courier, the bill of lading will become part of the COC 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 COC is still intact. The laboratory will maintain the COC
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 Eurofins Environment Testing for this project.
The laboratory 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 “J 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
Assessment Work Plan for Soil, Soil Gas, and Groundwater
Greenhouse Project / 601 N. Mangum Street, Durham, NC
Brownfields Project Name: N. Mangum Street Properties II
NCDEQ, Brownfields Project No.: 20593-21-032
S&ME Project No. 213673
June 8, 2022 12
coordinate the removal of the drums from the site. For purposes of this proposal, 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.
7.0 Reporting
Following receipt of the laboratory analyses and results, S&ME will prepare and submit a letter report including
the following information:
Introduction: Describes the site conditions as 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.
Field Data Collection sheets, including groundwater purging parameters, 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 Greenhouse Project/N. Mangum
Street Properties II, which were considered in preparing this assessment work plan.
February 20, 2007 – Phase I Environmental Site Assessment Report, prepared by Piedmont Geologic,
P.C.
February 20, 2007 – Results of REC File Review, prepared by Piedmont Geologic, P.C.
March 2, 2007 - Environmental Site Assessment Addendum, prepared by Piedmont Geologic, P.C.
June 8, 2007 – Phase I Environmental Site Assessment Report, prepared by Dunklee & Dunham, P.C.
August 20, 2019 – Phase I Environmental Site Assessment Report, prepared by Dunklee & Dunham, P.C.
June 9, 2021 – Geotechnical Exploration Report, prepared by S&ME, Inc.
ATTACHMENTS
USGS The National Map: National Boundaries Dataset, 3DEP ElevationProgram, Geographic Names Information System, National HydrographyDataset, National Land Cover Database, National Structures Dataset, andNational Transportation Dataset; USGS Global Ecosystems; U.S. CensusBureau TIGER/Line data; USFS Road Data; Natural Earth Data; U.S.Department of State Humanitarian Information Unit; and NOAA NationalCenters for Environmental Information, U.S. Coastal Relief Model. Datarefreshed August, 2021.Subject Property
SCALE:
DATE:
PROJECT NUMBER
FIGURE NO.
11 " = 2,000 '
5-25-22
213673
GREENHOUSE PROJECT601 SOUTH MANGUM STREETDURHAM, DURHAM COUNTY, NORTH CAROLINA
Drawing Path: T:\GEO\Projects\2021\213673_Mangum(Four Points Dev)_Greenhouse Project_Durham, NC\!GIS\Brownfields Assessment\Vicinity Map.mxd plotted by lhester 05-25-2022
0 2,000 4,000(FEET)
VICINITY MAP
³
REFERENCE:GIS BASE LAYERS WERE OBTAINED FROM THE USGS NATIONAL TOPOGRAPHIC BASEMAP.THIS MAP IS FOR INFORMATIONAL PURPOSES ONLY. ALL FEATURE LOCATIONS DISPLAYEDARE APPROXIMATED. THEY ARE NOT BASED ON CIVIL SURVEY INFORMATION, UNLESSSTATED OTHERWISE.
North
St
Durham County Parcels
SCALE:
DATE:
PROJECT NUMBER
FIGURE NO.
2
1 " = 61 '
2-24-22
213673
GREENHOUSE
PROJECT
601
SOUTH
MAGNUM
STREET
DURHAM,
DURHAM
COUNTY,
NORTH
CAROLINA
DrawingPath:
Z:\Shared\SME\Ops\GEO\Projects\2021\213673_Mangum(Four
Points
Dev)_Greenhouse
Project_Durham,
NC\GIS\Brownfields
Assessment\Site
Plan.mxdplottedbylhester
02-24-2022
0 100 200
(FEET)
SAMPLE
LOCATION
PLAN
REFERENCE:
GIS BASE LAYERS WERE OBTAINED FROM XXXXXXXX. THIS MAP IS FOR INFORMATIONAL
PURPOSES ONLY. ALL FEATURE LOCATIONS DISPLAYED ARE APPROXIMATED. THEY ARE
NOT BASED ON CIVIL SURVEY INFORMATION, UNLESS STATED OTHERWISE.
Proposed Groundwater /Soil Sample Location
Proposed Soil Gas Sample/Soil Sample Location
Proposed Soil Sample Location
North St
Dowd St
N Mangum St
Hunt St
Broadway St
Durham County Parcels
SCALE:
DATE:
PROJECT NUMBER
FIGURE NO.
3
1 " = 61 '
2-24-22
213673
GREENHOUSE PROJECT
601 SOUTH MAGNUM STREET
DURHAM, DURHAM COUNTY, NORTH CAROLINA
Drawing Path: Z:\Shared\SME\Ops\GEO\Projects\2021\213673_Mangum(Four Points Dev)_Greenhouse Project_Durham, NC\GIS\Brownfields Assessment\Site Plan.mxd plotted by lhester 02-24-2022
0 100 200
(FEET)
PREVIOUS SITE INVESTIGATIONS
³
REFERENCE:GIS BASE LAYERS WERE OBTAINED FROM XXXXXXXX. THIS MAP IS FOR INFORMATIONALPURPOSES ONLY. ALL FEATURE LOCATIONS DISPLAYED ARE APPROXIMATED. THEY ARENOT BASED ON CIVIL SURVEY INFORMATION, UNLESS STATED OTHERWISE.
UPUP
UP
UP
2S/2
R
2S/2
R2S/2
R2S/2
R
2S/2R
2S/2
R
UP UPUP
UP
UP
UP
RISERROOM
LOBBY
LOBBY
MAIL
PATIO
7.81%
LEASING
STORAGE
RETAIL
RETAIL
RETAIL
RETAIL
STAIR
ELEVATOR
TRASH
LOADINGUNITUNITUNIT
TERRACE
STAIR
BIKEPARKING
UNIT UNIT UNIT UNIT UNIT
ELEVATOR
ELEVATOR
STAIR
DOGWASH
UNIT
UNIT
13.74%
VAN
UP DOWN
GRADING & STORM DRAINAGE PLAN
1" = 20'SD-3.0
1
SD-3.00201040
GRADING &STORMDRAINAGE PLAN
RevisionsDateCheckedDrawn
JSA, PBRDAD
2047
01-04-2022 SP SUB #1
111 West Main StreetDurham, N.C. 27701
p 919.682.0368f 919.688.5646www.cjtpa.com
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NC BOARD OF EXAMINERS FORENGINEERS AND SURVEYORSLIC # C-1209NC BOARD OF LANDSCAPEARCHITECTS LIC # C-104
04-01-2022 SP SUB #2
grading and storm drainage notes
ADA route notes applies to all sheets
BUILDING HEIGHT - GRADE CALCULATION
Date: 6/8/2022
SG-1 390 390 0 6 4 to 6
SG-2 389 390 -1 6 4 to 6
SG-3 387 387.4 -0.4 6 4 to 6
SG-4 387 387.4 -0.4 6 4 to 6
SG-5 385 385 0 6 4 to 6
SG-6 384 384 0 6 4 to 6
SG-7 390 390 0 6 4 to 6
SG-8 390 390 0 6 4 to 6
GW-1 390 390 0 20 10-20
GW-2 390 390 0 20 10-20
GW-3 388 390 -2 20 10-20
GW-4 392 392 0 20 10-20
SS-1 390 390 0 6 5
SS-2 390 390 0 6 5
SS-3 389 389 0 6 5
Notes:
ft. AMSL: Feet Above Mean Sea Level RCRA: Resource Conservation and Recovery Act
ft. BGS: Feet Below Ground Surface See Figure 2 for Proposed Sample Locations
VOCs: Volatile Organic Compounds See Figure 4 for Site Grading Plan
SVOCs: Semi-Volatile Organic Compounds Cr6 - Hexavalent Chromium
Soil
VOCs/8260
SVOCS/625 RCRA 8
Metals and Cr6
Determine soil conditions in the
proposed structure footprint.
Three plus soil samples
collected from soil gas and
groundwater borings
four plus one blind
duplicate (total is 5)Groundwater
VOCs/8260
SVOCS/625 RCRA 8
Metals and Cr6
Determine groundwater quality and
flow direction in proposed structure
footprint.
Current Surface
Elevation
(Ft. AMSL)
Proposed
Final Floor
Elevation (Ft.
AMSL)
Soil Gas TO-15 + Naphthalene
Determine need for vapor mitigation
system for proposed structure
footprint.
Boring
Depth
(ft. BGS)
Sample
Interval
(ft. BGS)
No. of Samples Proposed Analyses PurposeSample Media
Eight plus one blind
duplicate (total is 9)
S&ME Project No. 213673
Proposed
Excavation
Depth
(ft. BGS)
TABLE 1
Summary of Sample Point Information
Greenhouse Project
Brownfields Project Name: N. Mangum St. Properties II
Brownfields Project No. 20593-21-032
Sample ID