24020_Peerless Master Cleaners Dyers_DM_20231117

DECISION MEMORANDUM
DATE: November 17, 2023
FROM: Stephanie Graham
TO: BF Assessment File
RE: Peerless Master Cleaners and Dyers
501 Hillsborough Street, 500 W. Morgan Street; and 10 S. West Street
Raleigh, Wake County
BF # 24020-20-092
Based on the following information, it has been determined that the above referenced
site, whose intended use is for no uses other than high density residential, retail, office,
hotel, recreation, associated parking, and subject to NC Department of Environmental
Quality (DEQ) prior written approval, other commercial uses, can be made suitable for
such uses.
Introduction:
The Prospective Developer (PD) is Hennepin Ventures LLC located at 1212 New York
Avenue NW, Suite 1000, Washington, DC 20005. Hennepin Interests LLC, of the same
address, is the manager of Hennepin Ventures LLC. Keith P. Harney is the entity contact
for the PD. The PD entity is also affiliated with Dalian Development, also of the same
address, with Marston Smith of that company acting as the PD's representative.
The Brownfields Property consists of a 1.12-acre property identified by parcel
identification number (PIN) 1703498069. Prior to October 2023, the Brownfields
Property consisted of multiple parcels and associated addresses formerly identified as
5011503, 509, 513 & 515 Hillsborough Street (PINs 1703499156, 1703498193,
1703498135, 1703497166, respectively); 502, 510, 512 & 514 W. Morgan Street
(PINsl703499022, 1703488949, 1703498033, 1703497057, respectively); and 10 S.
West Street (PIN 1703499059), Raleigh, NC.
The Brownfields Property consists of four unoccupied commercial buildings and
associated paved surface parking.
Redevelopment Plans:
The PD plans to redevelop the property with a 13-story, high -density residential building
that includes nine to ten floors of residential units over three to four levels of
aboveground parking and retail space, and subject to DEQ prior written approval, other
commercial uses. The existing buildings will be demolished.
Site Historv:
Previous uses of the Brownfields Property include single-family residential structures (at
least 1903-1940s) and four commercial buildings constructed in 1935, 1941, 1954
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(including a basement) and 1959. Previous tenants of these buildings include but are not
limited to various retail operations, autobody repair (1940s-1950s), automotive repair
(1940s-at least 2010), drycleaners (at least 1936-1972), cleaning and dyeing and printing
operations (1940s-1970s), and most recently offices, a violin maker, a basement bar, and
an outdoor equipment and repair facility with a paint room.
Site assessment at the Brownfields Property from 2019 through 2022 identified impacts
from various petroleum and chlorinated solvent compounds above applicable standards.
In 2005, an underground storage tank or vault structure with two metal caps was
observed south of the 501 Hillsborough Street building on the northeastern portion of the
Brownfields Property. This structure was found to extend approximately six feet below
ground surface (bgs). The use of the underground structure was not confirmed in
historical records; however, it was reported to likely have been used as an oil/water
separator or wastewater sump. Neither the 2005 field screening activities, nor the soil and
groundwater sampling collected in the proximal area in 2019 identified contaminants of
concern (COCs) from this structure.
Potential Receptors:
Potential receptors include future onsite residents, visitors, onsite workers, construction
workers, and trespassers.
Contaminated Media:
DEQ has evaluated data collected from the following media at the subject property: soil,
groundwater, exterior 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. Exhibit 2 of the Brownfields Agreement provides specific sample locations, dates,
and COCs.
Risk Calculations
Risk calculations were performed using the July 2023 DEQ Risk Calculator
https: Hdeq.nc. gov/permits-rules/risk-based-remediation/risk-evaluation-resources.
For the purposes of looking at the site spatially, the site was addressed as a whole but
distinguishes between exterior soil gas and sub -slab soil vapor samples, with the first risk
calculator below including groundwater, soil and sub -slab vapor, and a second risk
calculator only based on the exterior soil gas results. This allows a comparison of the
risk associated with sub -slab soil vapor verses that based on exterior soil gas results only.
The risk calculations indicated the following based on available data, including the
following media: groundwater, residual soil, exterior soil gas and sub -slab vapor.
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Risk for Individual Pathways 1
Version Date: July 2023
Basis: May 2023 EPA RSL Table
Site ID: 24020-20-092
Exposure Unit ID: Sitewide GW, Soil & Sub -slab Vapor
DIRECT CONTACT SOIL AND WATER CALCULATORS
Receptor
Pathway
Carc inogenic
Risk
Hazard Index
Risk exceeded?
Resident
Soil
1.9E-05
1.1E+00
YES
Groundwater Use*
5.4E-04
9.0E+00
YES
Non -Residential Worker
Soil
3.4E-06
1.8E-01
NO
Groundwater Use*
8.4E-05
2.0E+00
YES
Construction Worker
Soil
7.4E-07
6.2E-01
NO
Recreator/'Trespasser
Soil
8.2E-06
3.2E-01
NO
Surface Water*
NC
NC
NC
VAPOR INTRUSION CALCULATORS
Receptor
Pathway
Carcinogenic
Risk
Hazardlndex
Risk exceeded?
Resident
Groundwater to Indoor Air
1.2E-05
2.9E+00
YES
Soil Gas to Indoor Air
1.6E-05
7.5E-01
NO
Indoor Air
NC
NC
NC
Non -Residential Worker
Groundwater to Indoor Air
2.7E-06
7.0E-01
NO
Soil Gas to Indoor Air
1.2E-06
5.9E-02
NO
Indoor Air
NC
NC
NC
The sitewide risk calculator summary output indicates that the maximum acceptable
regulatory carcinogenic risk range of lE-4 is exceeded for the direct residential
groundwater exposure pathway; however, no additional carcinogenic risk exposure
pathways were exceeded. The non -cancer hazard index (HI) threshold of 1.0 is exceeded
for direct residential soil and groundwater pathways as well as the direct non-residential
groundwater exposure pathway.
The calculated vapor intrusion risk output indicates that the non -cancer HI threshold of
1.0 is exceeded for the residential groundwater to indoor air exposure pathway. Based on
the presence of trichloroethene (TCE) in sub -slab vapor above residential VISLs, and the
calculated residential soil gas to indoor air vapor intrusion value of 0.75, a VIMS system
is recommended. Pre -occupancy and post -occupancy sampling will be required.
Soil
Soil data from the Brownfields Property has been collected from as early as 2005 through
2022 to a depth of 15 feet bgs. A geotechnical investigation was also completed in 2020
to a depth of 78.5 feet bgs, which identified significant fill comprised of organic debris,
rock and brick fragments, concrete and asphalt from 3 to 13 feet bgs, and a significant
petroleum odor in a boring (B5) located on the north side of the building facing Morgan
Street.
Several compounds, including arsenic, benzo(a)pyrene, hexavalent chromium,
naphthalene, and 1,2,4-trimethylbenzene were detected in onsite soils above their
respective DEQ Preliminary Soil Remedial Goals (PSRGs) for residential land uses, with
1,2,4-trimethylbenzene driving the risk for the non -cancer HI for direct exposure to
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residential soil of 1.1. Other compounds were detected in site soil, including
benzo(g,h,i)perylene, 4-isopropyltoluene, and phenanthrene, but there are no established
PSRGs for these compounds.
Groundwater
The most recent groundwater assessment was completed in 2022 and consisted of the
collection of 18 samples, including three duplicates. Site groundwater results indicated
concentrations of chlorinated and petroleum VOCs, a semi-VOC, and metals in excess of
their respective NC 2L groundwater standards. Various groundwater contaminants
detected in 2022 at the Brownfields Property exceed the Residential Vapor Intrusion
Screening Levels (VISLs) for VOCs in groundwater. The report summarizing the 2005
assessment was missing the analytical data; therefore, while reviewed by the Brownfields
Program, no data reported from the 2005 investigation was included in the risk calculator
but is provided on Exhibit 2 to the Brownfields Agreement for documentation purposes
only.
Mercury, naphthalene, cadmium, barium, hexavalent chromium, and trichloroethylene
(TCE) concentrations in groundwater are driving the risk for the direct groundwater
exposure calculation, while mercury and naphthalene drive the risk for non-residential
direct groundwater use, and mercury drives the risk for the calculated residential
groundwater to indoor air risk.
As a result of the plat parcel combination completed in October 2023, groundwater
assessment locations GW-4 and GW-7 are no longer within the boundaries of the
Brownfields Property. These samples were removed from Exhibit 2, and the sitewide risk
calculator was updated to reflect this change affecting the southern Brownfields Property
boundary.
Sub -Slab Vapor
Thirteen sub -slab vapor samples, including two duplicates, were collected on the
Brownfields Property in 2022. Sample SG-2 and its duplicate (DUP-6) were collected
approximately 6 feet bgs, due to the presence of a crawl space. The remaining sub -slab
samples were collected from installed Vapor Pins. Benzene, chloroform, 1,4-
dichlorobenzene, tetrachloroethene (PCE) and TCE exceeded their respective residential
VISLs for soil vapor. Other compounds detected in these sub -slab vapor samples include
acetone, 1,3-dichlorobenzene, cis-1,2 dichloroethene, ethanol, 4-ethyltoluene,
trichlorofluoromethane, and 2,2,4-trimethylpentane, but there are no established VISLs
for these compounds.
The concentrations of PCE and TCE in sub -slab vapor drive the risk for the calculated
soil gas to indoor air value. The non -cancer HI of 0.75 that is based on these and other
compounds is less than the threshold level of 1.0 but falls within a range for which the
Brownfields Program is recommending a VIMS for residential uses.
Surface Water
No surface water is located on the Brownfields Property.
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Indoor Air
Indoor air samples were not collected in the Brownfields Property buildings; however, all
existing buildings will be demolished prior to redevelopment.
Below is the risk output for just the exterior soil gas samples collected across the site to
distinguish the output from those results based on sub -slab vapor data.
Risk for Individual Pathways
Version Date: July 2023
Basis: May 2023 EPA RSL Table
Site ID: 24020-20-092
Ex sure Unit ID: Exterior SoilGas
DIRECT CONTACT SOIL AND WATER CALCULATORS
Receptor
Pathway
Carc inogenic
Risk
Hazardlndex
Risk exceeded?
Resident
Soil
NC
NC
NC
Groundwater Use*
NC
NC
NC
Non -Residential Worker
Soil
NC
NC
NC
Groundwater Use*
NC
NC
NC
Construction Worker
Soil
NC
NC
NC
Recreator/rrespasser
Soil
NC
NC
NC
Surface Water*
NC
NC
NC
VAPOR INTRUSION CALCULATORS Rd
Receptor
Pathway
Carciin genic
Fi
Hazardhidex
Risk exceeded?
Resident
Groundwater to Indoor Air
NC
NC
NC
Soil Gas to Indoor Air
1.2E-05
4.5E-01
NO
Indoor Air
NC
NC
NC
Non -Residential Worker
Groundwater to Indoor Air
NC
NC
NC
Soil Gas to Indoor Air
8.9E-07
3.6E-02
NO
Indoor Air
NC
NC
NC
The exterior soil gas risk calculator summary output indicates that neither the
carcinogenic risk of lE-4 nor the non -cancer HI threshold of 1.0 is exceeded for the
residential or non-residential worker exposure pathways for vapor intrusion. Due to the
presence of TCE at the Brownfields Property and the HI of 0.45, the exterior soil gas risk
calculator output also points to a recommendation of a VIMS at this location for
residential uses. The risk is driven by 1,2-dichloropropane in exterior soil gas samples.
Exterior Soil Gas
Five exterior soil gas (SG) samples, including one duplicate, were collected on the
Brownfields Property in 2022. Two of these samples (SG-1 and SG-3) were collected in
the existing western parking lot, in the areas of planned stairwells within the proposed
building. Exterior samples SG-14 and SG-15 were collected on the southern portion of
the property, in the footprints of the former drycleaning and automotive repair buildings.
Benzene, chloroform, 1,2-dichloropropane, and ethylbenzene were detected above the
residential VISLs. Other compounds detected include acetone, ethanol, 4-ethyltoluene,
trichlorofluoromethane, and 2,2,4-trimethylpentane; however, residential VISLs have not
been established for these compounds.
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Land Use Restrictions:
The Brownfields Agreement will include the standard land use restrictions (LURs)
regarding land uses, the requirement for an approved Environmental Management Plan
(EMP), redevelopment reporting, prohibitions on groundwater use, restrictions on soil
disturbance, no soil import/export without DEQ approval, known contaminant uses,
notification, access, vapor intrusion and LUR update provisions.
Based on the site -specific data provided to the Brownfields program, the site reuse is
suitable as long as the agreed upon land use restrictions in the BFA are abided by.
Property Management Issues:
Although we are not requiring a VIMS, we are recommending the system due to the
presence of TCE, and the calculated vapor intrusion risk calculator output. At this time,
the PD team has not determined whether a VIMS will be installed at the site. After
construction, a final grade sampling workplan has been requested.
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