18050_CENCO_DM_20191120

DECISION MEMORANDUM
DATE: November 20, 2019
FROM: Sarah Young & Sharon Eckard
TO: BF Assessment File
RE: CENCO
Formerly 500 and 600 (currently 609) Melynda Road
Charlotte, Mecklenburg County
BF #18050-14-060
Based on the following information, it has been determined that the above referenced
site, whose intended use is for no uses other than transit, distribution, warehousing,
container yard and depot operations, limited truck, equipment, and container maintenance
and repairs, container sales, intermodal transportation services, associated parking, and
with prior written approval from DEQ, other commercial uses, can be made suitable for
such uses. Residential or sensitive population uses are strictly prohibited at the
Brownfields Property.
Introduction:
The Prospective Developer (PD) is Melynda Road Realty, LLC and its principal officer is
Tim A. Frye, Sr. of 4511 Keeter Drive, Charlotte, NC 28214. The Brownfields Property
was originally comprised of six parcels totaling 37.27 acres, but was modified since the
application was first submitted to two parcels totaling 13.75 acres (Parcel Nos. 05712101
and 05712102).
Parcel No. 05712102 is comprised of approximately 11.85 acres and is improved
with an onsite facility building, which recently was damaged by a fire, and a smaller
building erected to provide a working area after the fire damaged the main building. This
parcel was historically used for truck rinsing, transportation, and truck repair. An
unnamed stream is located on the easternmost boundary of this parcel. Solid waste
management units (SWMU) Nos. 3-28 are located on this parcel.
Parcel No. 05712101 is comprised of approximately 1.9 acres and includes a
man-made pond (SWMU No. 2), an unnamed stream that transects this parcel (flowing
north to south) and is connected to the man-made pond and two former impoundments
(SWMU No. 1). This parcel remains unused and consists of partially wooded and
vegetated land. The stream exits the Brownfields Property at its southern boundary.
These industrial parcels were evaluated under CERCLA decades ago and were originally
assessed by the DEQ predecessor Hazardous Waste Section under RCRA. The
wastewater impoundments (SWMU No. 1) were closed under RCRA in the early 1990s.
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Redevelopment Plans:
With approval from the Brownfields Program, the PD began operations at the
Brownfields Property for limited minor maintenance activities (welding, electrical repair,
& tire changes & minimal servicing of onsite equipment such as forklifts). PD arranges
for general truck maintenance activities (oil changes, fluid changes, and heavier repairs at
an off -site location. No oil changes or other fluid servicing of machinery is to be
conducted on the Brownfields Property. No container rinsing or cleaning will be
conducted at the Brownfields Property.
In 2018-2019, the eastern area of Parcel No. 05712102 was logged and graded. A gravel
parking lot, retention pond and associated drainage feature associated with the eastern
stream were subsequently constructed on this parcel. These actions were conducted under
the approved Environmental Management Plan dated February 1, 2019.
On the southern portion of this same parcel, an approximately 2,700 square foot steel -
enclosed building was constructed to provide a work space after the fire partially
damaged the main building.
Future redevelopment plans that will require a revised EMP should soil disturbance occur
will include construction of covered parking, fencing, and lighting on the eastern portion
of Parcel No. 05712102, and the addition of a railroad spur that could connect to the CSX
railroad line on the southern end of Parcel No. 05712102.
At the time of the Brownfields Agreement, there were no plans to disturb the man-made
pond (SWMU No. 2), the western most un-named stream, and the former impoundments
that are all located on Parcel No. 05712101.
Site History:
The onsite main facility building, located on Parcel No. 05712102, was constructed in
1969. The main building is approximately 14,350 square feet with a slab on grade
foundation and two-story office area. The main building includes an office, maintenance
garage, historic truck washing bays, and surrounding gravel and pavement parking area.
On November 6, 2018, a fire at the main building caused damage to the building. The
PD is considering renovations to the main building at this time.
The Brownfields Property is listed as a Hazardous Waste (HW) and Inactive Hazardous
Sites Branch (IHSB) site with the facility names of Honbarrier Inc. and Central Transport
Company, respectively, and corresponding Facility ID No. NCD046148540. The
Brownfields Property is also listed under the Hazardous Waste Site Facility Name: Cenco
Inc. and Facility ID No. NCD982131054.
The Brownfields Property was reviewed under the Comprehensive Environmental
Response, Compensation, and Liability Information System (CERCLIS) in 1987. After
preliminary assessment was completed, the property was deferred to Resource
Conservation and Recovery Act (RCRA) corrective action in 1992, was archived in 1996,
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and was transferred to the DEQ predecessor Groundwater Section in 1998. In 2008,
DEQ was reorganized and the property was assigned the IHSB facility ID number listed
above.
In the 1980s and 1990s, environmental investigation and cleanup activities at the site
were conducted under oversight of DEQ's (predecessor) Division of Waste Management,
Hazardous Waste Section because Central Transport, Inc. (CTI, Inc.) operations were
regulated under RCRA. On May 30, 1990, CTI and the DEQ's predecessor Hazardous
Waste Branch entered into an Administrative Order on Consent to address conditions at
the site, including managing the former waste impoundments in accordance with the
Solid Waste Management Act. There are 28 Solid Waste Management Units (SWMU)
located on portions of Parcel Nos. 05712102 and 05712101.
The description of the SWMUs and their history is provided in the Brownfields
Agreement. The two former wastewater treatment ponds were closed under the Resource
Conservation and Recovery Act (RCRA) and as a result two Notices of Property
Restriction (NPR) under 40 CFR Subpart G Regulations were filed in the Mecklenburg
County Register of Deeds on October 28, 1994 (Book 07954, Page 0882/Map Book 26,
Page 379 & Book 07954, Page 0877). These NPRs shall be cancelled by DEQ.
From February 19 to February 20, 2018, the following ASTs were removed from the
Brownfields Property under the DEQ-approved January 29, 2018 EMP:
• 2- 20,000-gallon empty product storage tanks associated with SWMU No. 25;
• 2- 12,000-gallon empty fuel oil tanks associated with SWMU No. 19;
• 2- 6,000-gallon empty wastewater holding tanks associated with SWMU No. 11;
and
• 1- 10,000-gallon empty water holding tank located on the north side of the onsite
main building.
Additional assessment of groundwater, sub -slab vapor, surface water, & soil in various
areas of the Brownfields Property has been performed to support site activities and the
preparation of a Brownfields Agreement.
Potential Receptors:
Potential receptors are: construction workers, on -site workers, visitors, and trespassers.
Contaminated Media:
DEQ has evaluated data collected from the following media at the subject property:
surface water, groundwater, soil, soil gas, and sub -slab soil vapor. DEQ relies on the
following data to base its conclusions regarding the subject property and its suitability for
its intended reuse.
Soil
Soil sample results for SWMUs 5, 7, 9, 10, 22, 23, 24, and 27 were reported in 1995 and
1996. Methylene chloride and acetone were detected in soil samples. No VOC, SVOCs,
or metals were detected at concentrations that exceeded the Industrial/Commercial Health
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Based PSRGs (May 2019 version), with the exception of a detection of 1,2,4-
trichlorobenzene (CT-3) at 12 feet below the ground surface (bgs). Total chromium
(presumed to be primarily chromium III) ranged from 7.8 to 286 mg/kg.
In 2018-2019, additional soil assessment was conducted in SWMU No. 22, 23, and 24,
with the sampling depth and location representative of soil disturbance plans outlined in
the February 1, 2019 EMP and associated work plan. Elevated detections of Aroclor 1254
in composite sample SB-28/SB-29 (2-3 ft bgs) and subsequent detections of PCB 105,
118, 126, and high risk PCBs at concentrations above the Industrial/Commercial Health
Based PSRGs (May 2019 version) were identified in soil sample SB-29A (2-3 ft bgs)
within SWMU No. 22 (filled in trench) footprint.
Two additional soil samples (SB-35 and 36) were collected from within the SWMU No.
2 footprint at a depth representative of the planned one (1) foot depth cut area. No
detections within these samples were identified above the Industrial/Commercial Health
Based PSRGs (May 2019 version).
A total of twenty soil samples were collected from the footprint of the SWMU No. 22
and submitted for laboratory analysis of PCBs (EPA 8082). Of the twenty soil samples,
only one soil sample (SB-54) resulted in a detection of a PCB compound, specifically,
Aroclor 1254, above the Industrial/Commercial Health Based PSRGs (May 2019
version). This sample was submitted for additional laboratory analysis in which PCB 126
and the high risk PCBs were detected above the Industrial/Commercial Health Based
PSRGs (May 2019 version). As a result, the trench footprint will be overlain with a
geotextile barrier and a minimum of six (6) inches of crush and run gravel in accordance
with the DEQ-approved February 1, 2019 EMP.
An additional soil sample(SB-58) collected at a depth of 0.5-2.5 feet bgs in a proposed
cut area of the drainage feature associated with the retention pond area exhibited green
staining and was found to be associated with a concentration of 3,090 mg/kg
bis(2ethylhexyl)phthalate in excess of its industrial screening level of 160 mg/kg;
however, approximately 50 cubic yards of soil from this area was excavated, temporarily
stockpiled onsite, and transported offsite by EVO Corporation of Winston-Salem, NC on
Friday September 27, 2019. Confirmatory samples (CS -BASE and CS -SIDES) from the
SB-58 excavation were submitted for laboratory analysis, where no exceedances of bis(2-
ethylhexl) phthalate, hexavalent chromium or the RCRA metals were identified at
concentrations above the Industrial/Commercial Health Based PSRGs (May 2019
version).
Samples SB-66 Surface and SB-66 were located within the retention pond footprint.
These samples were collected post -excavation at 0-0.5 feet bgs and 5.5-5.7 feet bgs and
are characterized by detections of hexavalent chromium at 6.4 mg/kg and 230 mg/kg,
respectively. Approximately 330 cubic yards of impacted soil were excavated from
within the general area of these samples and stockpiled onsite. Three stockpile samples
(POND STOCKPILE-1, 2A and 2B) were submitted for laboratory analysis of RCRA
metals and hexavalent chromium. The results indicated that there were no detections that
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exceeded the Industrial/Commercial Health Based PSRGs (May 2019 version) and these
soils were reused as fill onsite.
Sediment
Man-made pond (SWMU No. 2)
The sludge from the man-made pond, Pond No. 3 (SWMU No. 2) located on Parcel No.
05712101 (west of the main facility building) was reported to be characterized by only
phthalate compounds historically. In January 2018, two sediment samples (PSED-1 and
PSED-2) were collected from the north and southern ends of this pond. Laboratory
analysis for EPA Methods 8260, 8270 and RCRA metals did not result in detections that
exceeded their respective Industrial/Commercial Health Based PSRGs (May 2019
version). Total chromium was detected at 16.2 mg/kg and 40.8 mg/kg.
Western un-named stream sediment
Sediment samples were collected from the stream that intersects Ponds No. 3 (SWMU
No. 2.) Laboratory analysis of the sediment samples for EPA Methods 8260, 8270, and
RCRA metals indicated no detections above their respective Industrial/Commercial
Health Based PSRGs (May 2019 version). Total chromium was detected in the sediment
samples at 22.8 mg/kg, 88.2 mg/kg, and 97.5 mg/kg.
Eastern un-named stream sediment
On February 6, 2019, three sediment samples (ESSED-1, 2 and 3) were collected from
the eastern most stream located on the Brownfields Property Parcel No. 05712102.
Detections identified in the laboratory analysis did not exceed Industrial/Commercial
Health Based PSRGs (May 2019 version), except for arsenic detected at ESSED-3 (3.8
mg/kg), which is within typical background concentrations for soils in this area.
Groundwater
Historically, 24 monitoring wells were installed as part of the assessment for the
property, with the initial data obtained as early as 1989. Currently, only six of the
original 24 monitoring wells exist with five of the existing monitoring wells located on
the Brownfields Property, and one monitoring well (MW-19) located offsite to the south
of the Brownfields Property. Historically, benzene up to 1,010 µg/L, chlorobenzene up
to 630 µg/L, 1,4-dichorobenzene up to 110 µg/L, 1,1-dichloroethane (1,1-DCA) up to
110 µg/L, cis-1,2-dichloroethene (cis-1,2-DCE) up to 590 µg/L, tetrachlorethene (PCE)
up to 35.7 µg/L, trichloroethene (TCE) up to 48.2 µg/L, and vinyl chloride up to 190
µg/L were detected in certain onsite wells.
The most recent groundwater sampling event available at the time the PD applied to the
Brownfields Program was conducted on February 25, 2014 when wells MW-2, MW-7,
MW-13, MW-16, MW-18, and offsite well MW-19 were sampled and analyzed for
VOCs (8260B), SVOCs (8270D), and metals (6010C). The respective monitoring wells
are located on the eastern side and downgradient of the impoundment (SWMU No. 1) on
the property, with the exception of MW-19, that is located offsite immediately south of
the Brownfields Property. Analysis of the groundwater samples in 2014 indicated that
benzene (up to 19 µg/L), chlorobenzene (up to 370 µg/L), cis-1,2-DCE (up to 380 µg/L),
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and vinyl chloride (up to 46 µg/L) were in exceedance of NC 2L Groundwater Standards
(April 1, 2013).
In February 2018, monitoring wells MW-7, MW-13, and the off -site well MW-19 were
resampled and subsequent laboratory analysis indicated that concentrations of benzene,
chlorobenzene, 1,4-DCB, 1,1-DCA, cis-1,2-DCE, PCE, TCE, and/or vinyl chloride in the
resampled wells was at least one order of magnitude lower than the maximum
concentrations for wells MW-7 and MW-13. An exception is that the concentration of
vinyl chloride in well MW-13 was reported at its maximum concentration in 2018.
Concentrations of constituents in offsite well MW-19 were fairly low with only one
detection of vinyl chloride at 0.49J exceeding the NC VISL for groundwater of 0.03 for
this compound.
Temporary monitoring wells (TW-series) were installed within the former footprints of
SWMU No. 26 (TW-7), SWMU No. 25 (TW-8), and SWMU No. 23 (TW-6).
Temporary monitoring wells were also installed upgradient of the onsite main facility
building (TW-4) and downgradient of the onsite facility building (TW-5) and adjacent to
the SWMU No. 19 containment pad (TW-9). Groundwater samples were collected from
these temporary monitoring wells and subsequent laboratory analyses detected (TCE) in
temporary wells TW-5, TW-6, TW-7, TW-8, TW-9, and PCE in temporary wells TW-5,
TW-7, TW-8, and TW-9 at concentrations that exceeded the NC 2L groundwater
standard for TCE of 3 µg/L and PCE of 0.7 µg/L, and the Non -Residential VISL
(February 2018) for TCE of 4.4 µg/L. PCE and TCE was not detected in temporary well
TW-4, which was located upgradient of the main building, in excess of either their
respective NC 2Ls nor their Non -Residential VISLs.
Surface Water
Western Most Stream
Surface water samples (SW-1 through SW-3) were collected from the stream that
intersects SWMU No. 2 to the west of the Brownfields Property. Laboratory analysis of
the surface water samples for EPA Methods 8260, 8270, and RCRA metals indicated no
detections above respective North Carolina 15A NCAC 02 Water Quality Standards for
Surface Waters, Water Supply (June 10, 2019 version) (NC 2B Standards). Total
chromium was detected in surface water samples at 1.2J µg/L and 1.4J µg/L. At the time
of this Brownfields Agreement there are no plans to reuse or disturb SWMU No. 2 or the
associated stream.
Eastern Most Stream
On February 6, 2019, two surface water samples (SW-4 and SW-5) were collected from
the easternmost stream. Chromium, lead, and mercury were detected in these water
samples ranging from 0.57 µg/L to 1.1 µg/L, at 0.2 µg/L, and ranging from 0.1 µg/L to
0.11 µg/L respectively in one or both of these samples. Neither chromium nor lead have
listed NC 2B Surface Water Standards, but mercury has an Aquatic Life and Secondary
Recreation Class C Freshwater Standard of 0.012 µg/L.
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Soil Vapor
Soil vapor samples were collected from the following locations: SWMU No. 26 (SGB-
1), SWMU No. 25 (SGB-2), SWMU No. 23 (SGB-3) at depths of from 6 to 19 feet bgs,
and analyzed by method TO-15. PCE was detected at concentrations that exceeded the
Non -Residential VISL (February 2018) in SGB-1 and 2, ranging from 4,250 µg/m3 to
10,800 µg/m3. No other VOCs were detected at concentrations exceeding an established
Non -Residential VISL.
Soil vapor samples (SGB-5/5A and SGB-6/6A) were also collected from the footprint of
a new proposed building at two depth intervals of approximately 5 feet bgs (SGB-5 and
SGB-6) and 20 ft bgs (SGB-5A and SGB-6A). PCE was detected in all four samples
ranging from 1,100 µg/m3 to 3,900 µg/m3, with this highest concentration in sample
SGB-6A exceeding the Non -Residential VISL (February 2018) of 3,500 µg/m3.
Sub -Slab Vapor
Six sub -slab soil vapor samples were collected from the onsite main facility building in
two events: January 30, 2018 and May 2, 2018. Samples were analyzed by Method TO-
15. Of these samples, detections of vinyl chloride up to 12,000 µg/m3 (SSV-2),
chloroform up to 825 µg/m3 (SSV-5), and PCE up to 6,340 µg/m3 (SSV-6) were above
their respective Non -Residential VISL (February 2018).
A sub -slab soil vapor sample was collected from the boiler building that was since
converted to use for dry goods storage (SSV-9), and the waste water treatment building
(SSV-7 and 8) on January 30, 2018. Both structures are located east of the two
wastewater impoundments and west of the onsite facility building. Concentrations of
2,2,4-trimethylpentane were found in all three samples ranging in concentration from 8.9
µg/m3 to 10,700 µg/m3, but there is no VISL for this compound. Of the other site
contaminants, on cis-1,2-DCE was detected in sample SSV-7 and its duplicate at a low
concentration range of 7.9 µg/m3 to 9.1 µg/m3.
Indoor Air
Even though certain VOCs, including PCE and vinyl chloride in sub -slab vapor exceeded
their respective Non -Residential Vapor Intrusion Screening Levels within the main
building, the risk calculator output indicated that an unacceptable risk to indoor air was
not likely. However, the PD is planning on renovating the main building after the fire
and if so, indoor air sampling may be warranted to confirm.
No indoor air sampling has been conducted in the newly constructed 2,700 square foot
building because soil gas sampling results located near the building when entered into the
DWM Risk Calculator did not indicate an unacceptable risk to indoor air. The
construction plans of the 2,700 square foot building and soil vapor samples (SGB-5/5A
and 6/6A) were reviewed internally by the Brownfields Program. The building was
assembled on site with metal walls, one standard door, three bay doors, and a suspended
HVAC system. The building was constructed on a concrete slab with two footers (2-3
feet deep) running along the outside edges of the slab.
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Risk Calculations
Risk calculations were performed using the DWM Risk Calculator (May 2019 version).
For the purposes of looking at the site spatially, the site was divided into three areas:
which are: 1) the former wastewater treatment area (SWMU Nos. 1 and 2, and the
samples collected west of, proximate to, and including within the main building; 2)
shallow soil samples collected at depths ranging from 0-5 feet bgs from the former
wastewater treatment area (SWMU Nos. 1 and 2, and the samples collected west of,
proximate to, and within the main building; 3) the eastern area of the site excluding the
trench area (SWMU No. 22); 4) Eastern portion of Brownfields Property, excluding the
"Area of Soil Contamination" delineated on the plat (SWMU No. 22 Footprint, including
final grade sample results); 5) the "Area of Soil Contamination", which is the best
approximation of the boundary of the unlined trench area (SWMU No. 22); 6) assessment
conducted within the footprint of the 2,700 square foot building, including soil gas
samples collected near the groundwater table; and 7) shallow soil gas samples collected
within the footprint of the 2,700 square foot building. The risk calculations indicated the
following based on available data, including the following media: groundwater, insitu
soil, residual soil (based on confirmatory soil data), soil gas, sub -slab vapor, sediment
and surface water:
1. Risk Calculator No. 1: SWMU Nos. 1 and 2, and area affected by wastewater
treatment building
Parcel No. 05712102: Main Facility Building and area to the west of the Main
Facility Building including SWMU No. 6, 3, 4, 5, 7,10, 9,11, 27, 15, 14, 13, 12, 8,17,
18, and 19.
Parcel No. 05712101: two former impoundments Pond No. 1 and Pond No. 2
(SWMU No. 1), Pond No. 3 (SWMU No. 2), and un-named stream.
Soil Samples include: Wastewater impoundment (SWMU No. 1) confirmatory samples,
historic SWMU samples located west of the existing facility building for which sample
data was available; soil samples collected adjacent to the main onsite facility building
(TW-4 and 5), S13-16, pond sediment, and western un-named stream sediment samples.
Sample depths ranged from 0-12 feet below ground surface (bgs).
Groundwater Samples include: the monitoring wells located west of the main facility
building (MW-2, 7, 18, 13, 16, 19 (offsite)); temporary monitoring well located adjacent
to the North side of the onsite main facility building (TW-4); the temporary monitoring
well located adjacent to the South side of the facility building (TMW-5 and TW-9)
Sub -Slab Soil Gas Samples include: the main facility building (SSV-1, 2, 3, 4, 5, and 6);
the boiler building utilized for dry goods storage (SSV-9); the waste water treatment
building (SSV-7 and 8).
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Surface Water Samples: Un-named stream located west of the main facility building
(SW-1, 2, and 3)
Risk for Individual Pathways (Risk Calculator No. 1)
P
Version Date:
May 2019
Basis: May 2019 EPA RSL Table
Site ID: CENCO
Exposure Unit ID: Described in the text above.
DIRECT CONTACT SOIL AND WATER CALCULATORS
Receptor
Pathway
Carcinogenic Risk
Hazard Index
Risk exceeded?
Soil
2.5E-05
7.7E+00
YES
Resident
Groundwater Use*
1.2E-02
6.9E+01
YES
Non -Residential
Soil
5.5E-06
1.1E+00
YES
Worker
Groundwater Use*
7.7E-04
1.4E+01
YES
Construction
Soil
1.9E-06
7.3E+00
YES
Worker
Soil
1.2E-05
2.6E+00
YES
Recreator/Trespasser
Surface Water*
2.3E-05
2.4E-02
NO
VAPOR INTRUSION CALCULATORS
Receptor
Pathway
Carcinogenic Risk
Hazard Index
Risk exceeded?
Groundwater to
Indoor Air
1.5E-03
1.6E+01
YES
Resident
Soil Gas to Indoor
2,4E-03
8.7E+00
YES
Air
Indoor Air
0.0E+00
0.0E+00
NO
Groundwater to
Indoor Air
1.2E-04
3.9E+00
YES
Non -Residential
Soil Gas to Indoor
Worker
Air
6.0E-05
6.9E-01
NO
Indoor Air
0.0E+00
0.0E+00
NO
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2. Risk Calculator No. 2: Shallow soil samples (0-5 ft bgs) from the SWMU Nos. 1
and 2, and area affected by wastewater treatment building.
Risk calculator No. 1 (above) included laboratory detections for soil samples collected
from depths that ranged from 0-12 feet bgs. Risk Calculator No. 2 (below) was completed
for soil samples collected from depths of 0-5 ft bg to better assess the risk for the non-
residential worker, recreator/trespasser, and construction worker disturbing soil at a
maximum depth of 5 feet below the ground surface. Risk Calculator No. 2 excludes soil
sample results collected from depths exceeding 5 feet.
Soil Samples:
Risk for Individual Pathways (Risk Calculator No. 2)
Version Date: May 2019
Basis: May 2019 EPA RSL Table
Site ID: CENCO
Exposure Unit ID: Described in the text above.
DIRECT CONTACT SOIL AND WATER CALCULATORS
Receptor
Pathway
Carcinogenic Risk
Hazard Index
Risk
exceeded?
Resident
Soil
5.2E-06
1.7E+00
YES
Groundwater Use*
NC
NC
NC
Non -Residential Worker
Soil
1.2E-06
1.4E-01
NO
Groundwater Use*
NC
NC
NC
Construction Worker
Soil
2.1E-07
1.2E+00
YES
Recreator/Trespasser
Soil
2.5E-06
9.0E-01
NO
Surface Water*
NC
NC
NC
Based on a review of Risk Calculators 1 and 2 (above) and subject to the areas for which
the respective data was collected, the following interpretations were made:
For the Pathway: Soil (Risk Calculator 1), at depths greater than 5 feet bgs, in areas for
which there is representative data, there are exceedances of risk for the following
receptors: resident, non-residential worker, construction worker, and recreator/trespasser.
For the Pathway: Soil (Risk Calculator 2), at depths of 0-5 feet bgs, in areas for which
there is representative data, there are exceedances of risk for the following receptors:
resident and construction worker.
As a result, residential use is prohibited in accordance with the BFA and soil disturbance
in these areas is prohibited unless prior Brownfields Program approval is provided.
Future Brownfields approval for future work in these areas will require an Environmental
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Management Plan (EMP), and likely representative soil sampling within the footprint and
depths of soil disturbance.
For the Pathway: Groundwater Use (Risk Calculator 1), there are exceedances of risk for
the following receptors: resident and non-residential worker. The BFA prohibits the use
of groundwater at the Brownfields Property.
For the Pathway: Groundwater to Indoor Air (Risk Calculator 1), there are exceedances
of risk for the following receptors: resident and non-residential worker. Subsequent soil
vapor assessment conducted in 2018 is discussed in the contamination section above. For
the Pathway: Soil Gas to Indoor Air, there are exceedances of risk for the residential
receptors. The Pathway: Soil Gas to Indoor Air was not exceeded for the non-residential
worker. The buildings, depicted on the plat, for which there is available sub -slab
assessment are: 1) the main onsite facility building; 2) the boiler building that was since
converted to use for dry goods storage; and 3) the waste water treatment building, which
is also used for dry goods storage.
3. Central and eastern portion of Brownfields Property, excluding the "Area of Soil
Contamination" delineated on the plat (SWMU No. 22 Footprint)
Soil Samples include: shallow soil samples collected along the SWMU No. 22 footprint
that will not be covered by geotextile barrier, surficial soil samples collected from
SWMU No. 22 (SB-26, 27 and TW-6), SWMU No. 24 (SB-30 and 31), deep soil samples
collected from the retention pond and drainage feature footprints (SB-59-60), SWMU
No. 21 and 28 (SB-17, 18, 19, 33, 34, and TW-7), SWMU No. 25 and 26 (SB-20-25,
TW-8), and SB-66 & SB-66 Surface. Sample depths ranged from 0-5 feet below ground
surface (bgs).
Groundwater Samples include: the monitoring wells located west of the main facility
building (MW-2, 7, 18, 13, 16, 19 (offsite)); temporary monitoring well located adjacent
to the north side of the onsite main facility building (TMW-4); and the temporary
monitoring well located adjacent to the south side of the facility building (TMW-5 and
TMW-9).
Soil Vapor Samples include: SGB-1, 2, 3, 5, 5A, 6, 6 (Dup-10), and 6A. The planned
2,700 square foot building will be constructed over SGB-5, 5A, 6, 6 (Dup-10), and 6A.
Surface Water Samples: Un-named stream located at the eastern boundary of the
Brownfields Property (SW-4 and SW-5)
Sediment Samples: eastern stream sediment samples (SW-4 and SW-5).
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Risk for Individual Pathways (Risk Calculator 3)
Version Date:
May 2019
Basis: May 2019 EPA RSL Table
Site ID: CENCO
Exposure Unit ID: Described Above
DIRECT
CONTACT SOIL
AND WATER CALCULATORS
Receptor
Pathway
Carciin kenic
Ri
Hazard Index
Risk exceeded?
7.6E-04
1.2E+00
YES
Soil
Resident
Groundwater Use*
1.0E-04
1.8E+01
YES
Non -Residential
Soil
3.7E-05
8.5E-02
NO
Worker
Groundwater Use*
1.7E-05
4.0E+00
YES
Construction
Soil
6.4E-05
4.8E-01
NO
Worker
YES
Soil
4.2E-04
6.8E-01
Recreator/Trespasser
Surface Water*
1.9E-05
8.1 E-02
NO
VAPOR INTRUSION CALCULATORS
Receptor
Pathway
Carcinogenic
Risk
Hazard Index
Risk exceeded?
Groundwater to
4.3E-05
1.0E+01
YES
Indoor Air
Resident
Soil Gas to Indoor
9.6E-05
9.7E+00
YES
Air
Indoor Air
0.0E+00
0.0E+00
NO
Groundwater to
7,0E-06
2.4E+00
YES
Indoor Air
Non -Residential
Soil Gas to Indoor
Worker
Air
7.3E-06
7.7E-01
NO
Indoor Air
0.0E+00
0.0E+00
NO
The results of Risk Calculator No. 3 indicate that acceptable environmental risk is
exceeded for residential soil and groundwater exposure pathways, but not for non-
residential soil or construction worker exposure pathways. An unacceptable risk is
calculated based on these data for a trespasser scenario, but this is addressed with Risk
Calculator No. 4 below. Vapor intrusion calculators indicated that residential exposure
pathways exceed acceptable environmental risk, and the groundwater to indoor air
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CENCO/ 18050-14-060/20NoQ019

pathway for non-residential exposures exceeds acceptable risk, but that the soil vapor to
indoor air pathway for non-residential scenarios is within acceptable limits.
4. Eastern portion of Brownfields Property, excluding the "Area of Soil
Contamination" delineated on the plat (SWMU No. 22 Footprint)
The risk for the recreator and trespassor was exceeded in the Risk Calculator No. 3
(above). A review of the data utilized in Risk Calculator No. 3 identified a detection of
hexavalent chromium as the driver for the exceedance of risk for the recreator and
trespasser pathway. This hexavalent chromium detection (230 mg/kg) was sampled at a
depth of 5.5-5.7 feet bgs within the planned retention pond area of the Brownfields
Property. Subsequently, surficial soil sampling was conducted in the area of this
exceedance and hexavalent chromium was detected at 6.4 mg/kg. Risk Calculator No. 4
was completed using the same data set as Risk Calculator No. 3 with the following
changes: the hexavalent chromium detection of 230 mg/kg at SB-66 was removed from
the risk calculator and replaced with the hexavalent chromium detection of 6.4 mg/kg
detected in the surficial soil sample, SB-66 Surface, to more accurately reflect the
concentrations in soil that a trespasser walking across the property may come in contact
with. With this change, Risk Calculator No. 4 indicates that there is no unacceptable
exceedance of environmental risk from surface soils either in residential, non-residential,
construction worker, nor trespasser scenarios.
Risk for Individual Pathways (Risk Calculator 4)
Version Date:
May 2019
Basis: May 2019 EPA RSL Table
Site ID:
Exposure Unit ID:
Described
Above.
DIRECT
CONTACT SOIL AND WATER
CALCULATORS
Receptor
Pathway
Carcinogenic
Risk
Hazard
Index
Risk exceeded.
Resident
Soil
2.7E-05
2.7E-01
NO
Groundwater Use*
NC
NC
NC
Non -Residential
Worker
Soil
2.4E-06
2.1E-02
NO
Groundwater Use*
NC
NC
NC
Construction
Worker
Soil
2.0E-06
1.8E-01
NO
Recreator/Trespasser
Soil
1.5E-05
1.5E-01
NO
Surface Water*
NC
NC
NC
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CENCO/ 18050-14-060/20NoQ019

5. Eastern portion of Brownfields Parcel, SWMU No. 22 Footprint, specifically the
Area of Soil Contamination" delineated on the plat.
Risk for Individual Pathways (Risk Calculator 5)
1 0 WIT
Version Date:
May 2019
Basis: May 2019 EPA RSL Table
Site ID: CENCO
Exposure Unit ID: SB-29/28, 29A, 28A, 54
DIRECT CONTACT SOIL AND WATER CALCULATORS
Receptor
Pathway
CarcinogenicRisk
Hazard Index
Risk exceeded.
Resident
Soil
1.3E-03
2.2E+01
YES
Groundwater Use*
NC
NC
NC
Non -Residential
Worker
Soil
1.2E-04
1.8E+00
YES
Groundwater Use*
NC
NC
NC
Construction
Worker
Soil
8.9E-05
3.9E+00
YES
Recreator/Trespasser
Soil
6.9E-04
1.2E+01
YES
Surface Water*
NC
NC
NC
Risk Calculator No. 5 was completed to address risk within the "Area of Soil
Contamination" delineated on the plat component of the Notice of Brownfields Property.
For the Pathway: Soil (Risk Calculator No. 5), within the "Area of Soil Contamination"
delineated on the plat, there is an exceedance of risk for the following receptors: resident,
non-residential worker, recreator/trespasser, and construction worker. As a result,
residential use is prohibited by the BFA, and the trench footprint will be overlain with a
geotextile barrier and a minimum of six (6) inches of crush and run gravel in accordance
with the DEQ-approved February 1, 2019 EMP, as discussed in the Contaminated Media:
Soil section above.
6. Environmental assessment conducting within the 2,700 square foot building (Risk
Calculators No. 6 and No. 7)
Soil Samples include: shallow soil samples (SB-33 and 34) were collected from within
the 2,700 square foot building proposed building footers.
Groundwater Sample include: the temporary monitoring well, TW-7, located within
proximity to the 2,700 square foot building.
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CENCO/ 1805 0-14-060/20Nov2019

Soil Vapor Samples include: SGB- 5, SG13-5A, SGB-6, SGB-6 (Dup-10), and SG13-6A.
SGB-5 and SGB-6 were collected at depths of approximately 5 ft bgs and SBG-5A and
SG13-6A from depths of 20 ft bgs.
Risk Calculator No. 6 contains soil gas samples collected at 20 feet bgs (SGB-5A and
6A) and Risk Calculator No. 7 contains soil gas samples collected at 5 feet bgs (SGB-5
and 6).
Risk for Individual Pathways (Risk Calculator 6)
Version Date: May 2019
Basis: May 2019 EPA RSL Table
Site ID: CENCO Deep Soil Gas ONLY SGB-5A and 6A
Exposure Unit ID: Shallow soil samples (SB-34 and 35) , groundwater (TW-7) and deep soil
as (SGB-5A and 6A) at 20 feet bgs
DIRECT CONTACT SOIL AND WATER CALCULATORS
Receptor
Pathway
Carcinogenic
Risk
Hazard Index
Risk
exceeded?
Resident
Soil
4.9E-06
1.1E-01
NO
Groundwater Use*
6.5E-05
1.2E+01
YES
Non -Residential
Worker
Soil
1.1E-06
8.7E-03
NO
Groundwater Use*
1.1E-05
2.6E+00
YES
Construction Worker
Soil
1.8E-07
8.6E-02
NO
Recreator/Trespasser
Soil
2.7E-06
5.8E-02
NO
Surface Water*
0.0E+00
0.0E+00
NO
VAPOR INTRUSION CALCULATORS
Receptor
Pathway
Carcinogenic
Risk
Hazard Index
Risk
exceeded?
Resident
Groundwater to Indoor Air
2.8E-05
6.5E+00
YES
Soil Gas to Indoor Air
6.6E-05
9.6E+00
YES
Indoor Air
0.0E+00
0.0E+00
NO
Non -Residential
Worker
Groundwater to Indoor Air
4.7E-06
1.5E+00
YES
Soil Gas to Indoor Air
5.0E-06
7.6E-01
NO
Indoor Air
0.0E+00
0.0E+00
NO
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7. Shallow soil gas assessment (SGB-5 and 6) conducting within the 2,700 square
foot building (Risk Calculator No. 7)
Risk for Individual Pathways (Risk Calculator 7)
Version Date: May 2019
Basis: May 2019 EPA RSL Table
Site ID: CENCO
Exposure Unit ID: Shallow soil gas samples SBG-5 and 6 (5 feet below ground surface)
VAPOR INTRUSION CALCULATORS
Receptor
Pathway
Carcinogenic
Hazard Index
Risk exceeded?
Resident
Groundwater to
Indoor Air
2.8E-05
6.5E+00
YES
Soil Gas to Indoor Air
2.2E-05
2.6E+00
YES
Indoor Air
0.0E+00
0.0E+00
NO
Non -Residential
Worker
Groundwater to
Indoor Air
4.7E-06
1.5E+00
YES
Soil Gas to Indoor Air
1.7E-06
2.IE-01
NO
Indoor Air
0.0E+00
0.0E+00
NO
Risk Calculators No. 6 and No. 7 specifically address environmental assessment
conducted within the 2,700 square foot building footprint. This building was constructed
to house workers after a fire damaged the main building. It is only approved for non-
residential worker use.
Risk Calculator No. 6 indicates that the soil beneath the building does not exceed risk for
the following receptors: resident, non-residential worker, construction worker, trespasser
and recreator. Risk exceedances for direct contact with groundwater were identified for
the following receptors: resident, non-residential worker, construction worker, trespasser
and recreator.
The risk for groundwater to indoor air was assessed using groundwater data from TW-7,
a temporary well located within proximity to the proposed building. Risk Calculator No.
6 indicates that risk is exceeded for groundwater to indoor air for the following receptors:
resident and non-residential worker. Soil gas assessment was conducted within the
footprint of the proposed 2,700 square foot building. Risk Calculator No. 6 utilizes soil
gas assessment results collected from near the groundwater table (SGB-5A and 6A).
Deeper soil gas samples collected immediately above the source of contamination are
likely to be more representative of what may come into contact with and accumulate
underneath the structure's slab over time. Risk Calculator No. 7 indicates that the risk is
exceeded for residential scenarios, but not for non-residential worker exposure pathways.
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Required Land Use Restrictions:
In order to address the exceedances of risk, the land use restrictions in the Brownfields
Agreement will include standard restrictions as to requirements for an EMP, no
groundwater use, water well abandonment, no surface water use, prohibitions for soil
disturbance without an EMP, nor the export or import of soil without data, notice, access,
and annual update form, and other prohibitions.
Also specifically for this site: residential and other sensitive population use will be
strictly prohibited at the Brownfields Property, land uses are limited to minor vehicle
repairs and special requirements regarding the storage of fuels and other chemical
products, and a cover including a demarcation barrier with a six-inch crush and run
gravel is required for the former unlined trench area delineated on the Brownfields Plat as
"Area of Soil Contamination". Such cover was installed in October 2019, but must be
maintained to prevent exposure to contaminated soil below and erosion of the cap
material.
In addition, no building may be constructed or modified on the Brownfields Property
without prior Brownfields approval, this includes additions to existing building
footprints, removal of existing building slabs, alterations to the HVAC system, etc. Such
work may require additional sampling dependent upon the owner's building plans. The
boiler building and wastewater treatment building have been approved for storage only;
changes to site use of the buildings may require additional testing.
Based on the site -specific data provided to the Brownfield program, the site reuse is
suitable for the site as long as the agreed upon land use restrictions in the BFA are abided
by.
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