HomeMy WebLinkAbout22002_Decision Memorandum_Overture Cary_20201022DECISION MEMORANDUM
DATE: October 16, 2020
FROM: Kelly Johnson & Kathleen Markey
TO: BF Assessment File
RE: Overture Cary
3624 Davis Drive
Cary, Wake County
BF Project No. 22002-18-092
Based on the following information, it has been determined that the above referenced
site, whose intended use is for no uses other than an age -restricted, senior residential
community, and associated parking, can be made suitable for such uses.
Introduction:
The Brownfields Property is approximately 6.93 acres and is currently vacant land. A cell
tower site is located adjacent to, but is excluded from, the Brownfields Property. The
Prospective Developer (PD) is CRP-GRP Overture Cary Owner, LLC. The principal
officer of Greystar GP II, LLC is Robert A. Faith.
Redevelopment Plans:
The PD began redevelopment of the Brownfields Property for an age -restricted (55+)
"Active Adult" senior housing community in June 2019. Occupancy is scheduled for
early 2021. This community will incorporate both indoor and outdoor amenity spaces as
well as an outdoor pool and will ultimately include approximately 189 residential units.
Approximately 13,000 cubic yards of the southeast portion of the site was cut, including
impacted soil that as disposed of offsite. Imported fill material was approved for use as
fill in the northwest area of the Brownfields Property. The water supply well located near
the former residence was abandoned by Acme Well Service Co. in accordance with
NCAC 2C rules.
Site History:
Historically, the site had been used for agricultural purposes and a single-family
residence. A portion of the Brownfields Property was used as a single-family residence
from 1988 until the PD demolished it in June 2019. There were two known household
debris piles that were historically associated with the demolition of the house. There was
a residential heating oil above ground storage tank (AST) associated with the residence
along the southwest side of the former residential building. As of 2001, the AST was
removed from the Brownfields Property, but evidence of a release from the AST was
observed. The release was confirmed by soil sampling beneath the former location of the
AST. The AST was not assigned an incident number by the DEQ Underground Storage
Tank (UST) Section in regard to the observed release. A total of 773.28 tons of
petroleum -impacted soil was excavated from this area between July 9, 2019 and July 12,
2019, and disposed of offsite at Earthtec of NC in Bear Creek, NC.
Potential Receptors:
Potential receptors are: construction workers, on -site workers, future residents, visitors,
animals, and trespassers.
Contaminated Media:
DEQ has evaluated data collected from the following media at the Brownfields Property:
soil and groundwater. DEQ relies on the following data to base its conclusions regarding
the Brownfields Property and its suitability for its intended reuse.
Soil
Soil samples were taken near the former AST associated with the former residential
structure. On April 15, 2019, three soil samples were obtained from an observed release
area in the vicinity of the former AST, and were screened for volatile organic compounds
(VOCs), semi -volatile organic compounds (SVOCs), and RCRA 8 Metals using the QED
field screening process. Additionally, due to historical uses, six soil samples were taken
in the vicinity of the two observed debris piles and near the cellular tower. The data from
the soil samples taken from the former AST area confirmed the presence of total
petroleum hydrocarbons (TPH) diesel range organics (DRO) and TPH gasoline range
organics (GRO) up to 1,255 milligrams/kilogram (mg/kg) DRO and 209.7 mg/kg GRO,
respectively. Analytical results from all soil samples indicated the presence of chromium
in soil up to 26 mg/kg, but it was deemed to be naturally occurring and in the form of
trivalent chromium due to the lack of historic industrial activity at the Brownfields
Property; therefore, the chromium values did not exceed the DWM Preliminary Soil
Remedial Goals (PSRGs) for chromium. Arsenic was detected above residential PSRGs
ranging from 1.6 mg/kg-5.5 mg/kg in soil samples SB-2, SB-3, SB-4, SB-6 and BG-1,
but these single -digit concentrations and the lack of former industrial activity at the
Brownfields Property suggest that the arsenic is also naturally occurring.
The petroleum -impacted soil was removed from the Brownfields Property in July 2019.
Confirmatory soil samples indicate VOC's and SVOC's below PSRGs. RCRA 8 metals
were tested and only Arsenic and Chromium was detected above PSRGs. Arsenic was
detected above PSRGs for SS-2, SS-5, SS-6, SS-7, SS-9, SS-10 and SS Duplicate.
Chromium. Chromium was detected above PSRGs for all samples taken however due to
historical uses of the property and the lack of industrial uses, both metals are believed to
be naturally occurring.
A total of approximately 5,000 cubic yards of imported fill soil was brought onto the
Brownfields Property. It was obtained from the Morrisville Carpenter (Ashton Woods)
Site, and was approved by the Brownfields Program for use at the site in October 2019
based on laboratory data provided on October 16, 2019 and a description of the borrow
pit and its history provided on October 15, 2019.
Groundwater
Under the direction of DEQ, one groundwater well, TW-1, was installed at the
Brownfields Property in the vicinity of the only known source: the former AST location.
A second well location was attempted downgradient of the cellular tower site, but hit
refusal before encountering groundwater. One groundwater sample was obtained from
temporary well TW-1 and sampled for VOCs, SVOCs and metals. The results indicated
that there were no SVOCs detected, and chloroform, which was the only VOC detected in
TW-1 was below its 70 microgram per liter (µg/L) NC 2L standard, and its Groundwater
Vapor Intrusion Screening Levels (VISLs) of XXX µg/L . Chromium was detected in
TMW-1 at 79 µg/L above its NC 2L standard of 10 µg/L. Lead was detected at its NC 2L
standard of 15 µg/L.
Surface Water
Surface water is not located on the site, although Hatches Pond is adjacent to the
Brownfields Property to the east.
Soil Vapor
Based on the low concentrations of VOCs detected in the groundwater sampling results
and the lack of recognized environmental conditions elsewhere on the Brownfields
Property, soil vapor was not evaluated on the Brownfields Property.
Sub -Slab Vapor
The only structure on the Brownfields Property was the two-story residence that was
demolished on June 6, 2019. Based on the low concentrations of VOCs in the
groundwater sampling results and historical use of the property, sub -slab vapor sampling
was not indicated on the Brownfields Property.
Indoor Air
The only structure on the Brownfields Property was the two-story residence that was
demolished on June 6, 2019. Based on the low concentrations of VOCs in the
groundwater sampling results and historical use of the property, indoor air sampling was
not indicated on the Brownfields Property.
Risk Calculations
Risk calculations were performed using the DEQ Risk Calculator (December 2019
version). For the purposes of looking at the site spatially, the site was evaluated as a
whole for soil and groundwater using the maximum concentrations identified in those
media. The risk calculations indicated the following based on available data, including
the following media: groundwater, residual soil:
Risk for Izdicidual Patliwaas
Version Date: Ilia- 2019
Basis: Max- 2019 EPA RSL Table
Site ID: 22002-18-092
Exposure Uxit TD: Parcel l & 2
DIRECT CONTACT SOIL AND WATER CALCULATORS
Receptor
Pathtsar
Carinotgsenic
Hazard Index
Risk exceeded?
46........................1.8E-4.1
Resident
.....................................................Soil................................................................_8.-$E
................................NO
. ......................
Groundwater Use*
2.5E-01
2.3E+03
YES
S°t7
a6........................1.:3E.-Q2................................NO
Ilan -Residential Worker
..... .................................................................1.:gE,
Groundwater Use*
5.0E-02
3.4E+02
YES
Construction worker
Soil
3_1E-07
1.4E-01
NO
Sorl
4.9E-06
4.8E-42
NO
Recreator.Trespasser
.........................................................r..............................................................................................................................
Surface Water
NI C
NC
NC
VAPOR ]IN TRti SIGN CALCUTATORS
Receptor
Pathwa4
Carcinogrenic
Hazard Ind
Risk exceeded?
Ris
Groundwater to Indoor Air
1.5E-a6
3.DE-DE
NO
Resident
..............................................................................................................................................................................................................................................................................
So>7 Gas to Indoor Air
.............................................................................................................................................................................................................................................................................
0.0E+00
0.6E+00
NO
Indoor Air
0.0E+06
0.0E+60
NO
Groundwater to Indoor Air
3.4E-07
7.1E-44
NO
Non -Residential Worker
.............................................................................................................................................................................................................................................................................
So>7 Gas to Indoor Air
..............................................................................................................................................................................................................................................................................
0.0E+00
0_QE+0O
NO
Indoor Air
0.6E+00
0.6E+60
NO
CONTADiINANT AiIGRATION CALCULATORS
Pathway
Source
Target Receptor Concentrations Fxceeded".
Source So>7..........
Exceedence of 2L at Receptor?
NM
Groundwater
.......................................................................................................................................
Source Groundwater
Exceedence of 2L at Receptor?
NM
Source Soil
Exceedence of 2B at Receptor?
NM
Surface Water
..................................................................................................................................................................................................................
Sc=cp. Groundwater
Exceedence of 2S at Receotor?
NM
The risk calculations for the groundwater and soil remaining on the Brownfields Property
indicates that carcinogenic risk and noncancer hazard indices are not exceeded for either
residential or nonresidential exposure scenarios for soil uses. Groundwater
concentrations indicate risk for residents and non-residential workers. In addition,
groundwater concentrations do not indicate a risk to indoor air quality for residential and
nonresidential exposure scenarios based on the groundwater sample collected at the
known source area at the Brownfields Property.
Risk For Individual Pathways
Version Date: Mav 2419
Basis: Mav 2019 EPA RSL Table
Site ID: 22002-11-p92
Exposure Unit ID: Fill Soil Oct.2, 2019 samples
DIRECT CONTACT SOIL. AND WATER CALCLI ATORS
Receptor
Pathway
Car �otgenic
Hazard bider
Rick exceeded?
�E. 46......................_7.-E.-42................................No....................
Resident.....................................................5°................................................................_�
Groundwater Use*
NC
NC
NC
S°>7
0?......................_5...1E-43
NO
Non -Residential Worker
..............................................................._5-0E
Groundwater Use*
NC
NC
NC
ConstructionWarker
So@
1.OE-07
5_1E-02
NO
So>7
1.5E-05
4.0E-02
NO
Recrealorffrespasser
.............................................................................................................................................................................................................................................................................
Surface Water*
NC
NC
NC
VAPOR INTRUSION CALCULATORS
Receptor
Paflmw
Car i otgenic
Hsui�bndex
Riskescee"?
Ris
Groundwater to Indoor Air
4.4E+00
0.0E+00
NO
Resident
..............................................................................................................................................................................................................................................................................
So>7 Gas to Indoor Air
.............................................................................................................................................................................................................................................................................
0.0E+00
4.4E+00
NO
Indoor Air
4.4E+00
0.0E+00
NO
Groundwater to Indoor Air
0.0E+44
4.4E+00
NO
Non -Residential 1'v arker
.............................................................................................................................................................................................................................................................................
So>7 Gas to Indoor Air
..............................................................................................................................................................................................................................................................................
0.4E+00
4.4E+00
NO
Indoor Air
0.0E+00
0.0E+00
NO
CONTAMINANT
MIGRATION CALCULATORS
IN
Padmay
Sanrce
Target Receptor Concentrations Esceeded?
Source Soil
Exceedence of 2L at Receptor?
NM
Groundwater
..........
.........................................................................................................................................
Source Groundwater
Exceedence of 2L at Receptor?
NM
Source Soil
Exceedence of 2B at Receptor?
NM
Surface Water
.........................................................................................................................................
Source Groundwater
1 Exceedence of 2B at Receptor?
NM
Risk Calculator run for Oct. 2, 2019 fill soil samples of approximately 5,000 cubic yards.
The risk calculator indicates that carcinogenic risk and noncancer hazard risk is not
exceeded for the imported soil.
Required Land Use Restrictions:
Based on the site history, available site data and the risk calculator output, the
Brownfields Agreement for this project will include standard land use restrictions with
regards to groundwater use, soil disturbance, soil import/export, vapor intrusion
mitigation, well abandonment, EMP and redevelopment summary report, notification and
access, known contaminants, and land use restriction update obligations.
Based on the site -specific data provided to the Brownfield program, the Brownfields
Property is suitable for the intended reuse as long as the agreed upon land use restrictions
in the BFA are abided by.
Brownfields Property Management Unit Issues: Non known.