HomeMy WebLinkAbout23077_Diversey Water Tech_Decision Memo_20210423DECISION MEMORANDUM
DATE: April 23, 2021
FROM: Kathleen Markey and Jordan Thompson
TO: BF Assessment File
RE: Diversey Water Technologies
1200, 1208, 1210 & 1212 S. Mint St. and 1201 S. Graham Street
Charlotte, Mecklenburg County
Brownfields Project No. 23077-19-060
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, recreational,
commercial and parking, can be made suitable for such uses.
Introduction:
The Brownfields Property consists of four parcels totaling approximately 1.606 acres of
land. The property is associated with Mecklenburg county Parcel Identification Numbers
07326604, 07326605, 07326606, and 07326607.
Redevelopment Plans:
The Prospective Developer (PD) has demolished the existing structures that are located
on the Brownfields Property. The PD intends to redevelop the Brownfields Property for
high density residential, recreational, parking, and commercial uses.
Site History:
The Brownfields Property was historically used for residential purposes prior to 1911.
Following that time, the Brownfields Property has been used for commercial purposes.
The eastern and northern portions of the site were utilized by two machine shops and a
welding shop by 1929. A propane gas supply company occupied the southern portion of
the former buildings from the 1950’s to the 1960’s. In the early 1950’s, an office
building was constructed on the southernmost parcel. A warehouse building was
constructed on the northern portion of the property in 1964 it was subsequently utilized
for: a manufacturer of chromium-based water treatment chemicals and fuel oil additives
(1960s to late 1990s), janitorial supply companies (1970s to 2000s), a heating,
ventilation, and air conditioning (“HVAC”) control panel repair business (mid-2000s to
mid-2010s), and a furniture and millwork company (late 2010s).
The welding shop and machine shop that had been on the property since the 1920’s was
demolished in the early 1970’s. A sign company occupied the property in the 1970’s,
followed by a steel rule die company in the late 1970’s, a printing company in the 1990’s
and medical offices in the 1990’s through the 2000’s. The Brownfields Site is also
associated with IHSB number NONCD0001610.
A former occupant of the Brownfields Property, Mechanical Systems & Services
(MS&S) (located at 1201 S. Graham St in the northeastern portion of the property), was
previously registered as a Resource Conservation and Recovery Act (RCRA) Large
Quantity Generator (LQG) of ignitable (D001), corrosive (D002), chromium (D007),
mercury (D009), carbamodithioic acid, bis-1,2-ethanediyl, salts and esters (U114),
hydrazine (U133), and TCE (U228) hazardous wastes. No RCRA compliance violations
were reported in connection with the facility.
The below figure depicts the Brownfields Property in a recent configuration and outlines
areas of concern based on former site operations.
Environmental Assessment Overview:
Soil and groundwater assessment activities were conducted in 1992 and 1993 in the
vicinity of the existing warehouse and adjoining office building. According to the June
1994 Investigation of the Diversey Water Technologies Inc. Site report (“1994 Report”),
chromium and lead were detected above the North Carolina Department of
Environmental Quality (“DEQ”) Residential Preliminary Soil Remediation Goals
(“PSRGs”) in shallow soil samples collected on the southwestern portion of the
Brownfields Property near an 18-inch diameter corrugated metal pipe. The former use of
the pipe is unknown. Metals, including nickel, chromium, iron, lead, and manganese
were detected above the North Carolina Administrative Code Title 15A Subchapter 2L
Standards (“2L Standards”) in groundwater samples collected at the Brownfields
Property. The 1994 Report also indicated trichloroethylene (TCE) was detected above
the 2L Groundwater Standard, with the highest concentration identified near the
northwestern corner of the Brownfields Property.
The detection of TCE was further evaluated and documented in the February 1997
Comprehensive Site Assessment Report, the highest concentrations of TCE in
groundwater were confirmed to be in the northwestern corner of the Brownfields
Property. Soil sampling did not indicate the presence of TCE, the report concluded that
the TCE was likely due to one or more off-site sources.
In 2019 a Phase II assessment was conducted, with the report issued in December 2019
including the collection of soil, groundwater, soil gas, and sub-slab vapor samples. This
assessment further documented the presence of TCE in groundwater in the northwest
portion of the property. The results above an applicable standard are summarized further
below. The Phase II assessment indicated that there was a detection of benzo(a)pyrene
and hexavalent chromium at concentrations above the residential PSRG for soil. The sub-
slab vapor and exterior soil gas results indicated the presence of multiple VOCs including
low concentrations of chlorinated and petroleum-related compounds. However, none of
these concentrations exceed the residential SGSLs.
A July 2020 Brownfields Assessment Report conducted as part of a work plan approved
by NCDEQ detailed results of additional soil, groundwater, and vapor intrusion sampling
conducted at the Brownfields Property in May 2020. One soil, one groundwater, seven
sub-slab vapor, and two soil gas samples were collected to obtain additional assessment
data and to confirm select historical vapor intrusion assessment results. Based on the
sub-slab results additional samples were collected in July 2020 and reported in the
August 2020 Vapor Intrusion Assessment Report. The results above an applicable
standard are summarized further below.
Potential Receptors:
Potential receptors are; construction workers, on-site workers, future residences, visitors
and trespassers.
Contaminated Media:
DEQ has evaluated data collected from the following media at the subject property: soil,
groundwater, soil vapor and soil gas. DEQ relies on the following data to base its
conclusions regarding the subject property and its suitability for its intended reuse.
Below is a sample location map depicting the most recent sample locations collected on
the Brownfields Property.
Soil
Soil samples were collected in assessments conducted in 1994, 2019 and 2020. The 1994
Report, conducted under IHSB supervision, indicated that nickel, chromium, iron, lead
and manganese were identified above residential IHSB Preliminary Soil Remediation
Goals (PSRGs). No VOCs were identified during the 1994 sampling event. The
December 2019 phase II identified arsenic and hexavalent chromium concentrations
above residential PSRGs. Benzo(a)pyrene was also detected at a concentration above the
residential PSRG. The 2019 phase II did not detect any VOCs above residential PSRGs.
The 2020 Brownfields Assessment Report identified arsenic above residential PSRGs
near the northern corner of the site. The 2020 sampling event did not identify VOC
concentrations above PSRGs and did not identify SVOCs at concentrations greater than
method detection limits.
Groundwater
Depth to groundwater is approximately 14.8 feet below ground surface to 36.07 ft below
ground surface and groundwater flow is northwest towards Irwin Creek. The 1994 Report
indicated the presence of trichloroethylene (TCE) in groundwater above 2L Standards
near the northwestern corner of the property. Following these results, additional
assessment was conducted from 1994-1996 to evaluate the source of the TCE. TCE
appears to be sourced from one or more off-site properties based on the concentrations in
the northwest and southwest area of the Brownfields Property. 1,2-Dichloroethane was
detected above the 2L standard in one deep groundwater sample collected in the
northwestern portion of the site. The 2019 phase II identified chromium above the 2L
standard near the northwestern and central portions of the site. TCE was also detected at
4.2 ug/L near the northwestern portion of the site in this assessment, consistent with the
historical groundwater data. In the 2020 Brownfields Assessment Report, chromium was
detected in the southern portion of the site at a concentration above the 2L standard. This
sample did not contain VOCs that were above the method detection limits.
Surface Water
Surface water is not located on the site.
Soil Vapor
Soil Vapor was not sampled at this site.
Sub-Slab Vapor and Soil Gas
In the December 2019 Phase II Environmental Site Assessment, Benzene, naphthalene,
and chloroform were identified near the southeastern portion of the Brownfields property
at concentrations exceeding the DEQ Residential Sub-slab and Exterior Soil Gas
Screening Levels (“SGSLs”). Chloroform and naphthalene exceeded the residential
SGSLs in one sub-slab vapor sample collected near the center of the property. In the
2020 Brownfields Assessment Report, benzene, ethylbenzene, naphthalene, and vinyl
chloride exceeded the residential SGSLs. The 2020 Brownfields Assessment Report also
identified the presence of 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzen and xylenes near
the northern, southern, and western portions of the site at concentrations exceeding
residential SGSLs. The northern portion of the site identified benzene, 1,2-
dichlorobenzene, 1,4- dichlorobenzene, ethylbenzene, naphthalene, 1,2,4-
trimethylbenzene, 1,3,5-trimethylbenzene, and/or xylenes at concentrations exceeding the
Residential SGSLs. The southernmost sub-slab sample that was collected in the August
21, 2020 report identified 1,2,4- trimethylbenzene that exceeded the Residential SGSLs.
Indoor Air
The onsite structures will be demolished, therefore indoor air was not evaluated on the
Brownfields Property.
Risk Calculations
The DEQ Risk Calculator was developed to evaluate the risk of multiple contaminants
and multiple exposure routes associated with contaminated environmental media at a site.
The risk evaluation procedures, equations, and default parameters used to create the
calculator follow the current USEPA risk assessment guidance. The DEQ Risk
Calculator dated July 2020 was used to evaluate the following.
The Brownfields Property was evaluated as a whole. The risk calculations indicated the
following based on available data, including the following media: groundwater, soil
(based on confirmatory soil data), soil gas, and sub-slab soil gas samples:
Based on the above risk calculations, exposure risk is exceeded for direct groundwater
contact for both residential and non-residential reuse due to the hazard index exceedance
of 1. Additionally, the risk calculator indicates that risk is exceeded for residential and
nonresidential vapor pathways for groundwater and soil gas to indoor air.
Based on available data for this site, the risk calculator indicates that for the planned
residential structures (as well as any potential future non-residential structures), vapor
intrusion and Hazard Index risk exceeds appropriate risk levels and that VI mitigation
measures approved by DEQ will be a necessary requirement of redevelopment plans on
the property.
Required Land Use Restrictions:
• There will be no use other than high density residential, retail, office, recreational,
parking, open space, and with prior written DEQ approval, other commercial
uses.
• No groundwater or surface water use.
• No disturbing soil without DEQ approval or for landscape/mowing/pruning/repair
of underground infrastructure (written notice to DEQ),
• Soil Import/Export must be approved by DEQ.
• Access to Brownfields Property for environmental assessment. \
• Standard vapor intrusion LUR.
• No childcare or adult care centers.
• NBP reference in deed.
• No contaminants (as included in Ex. 2 to the BFA) on property except for de
minimis amounts, fluid in vehicles, fuels for generators/equipment.
• Final grade sampling will occur for volatile organic compounds by EPA Method
8270, semi-volatile organic compounds by EPA Method 8270 and RCRA Metals
by EPA Methods 6020/7471.
Based on the site-specific data provided to the Brownfield program, the site reuse appears
suitable for the site as long as the agreed upon land use restrictions in the BFA are abided
by.
PMU NOTES
As part of active Brownfields work, an EMP and VIMP for this property have been
approved. As of recordation, the site buildings have been demolished and construction is
underway.
The VIMS is designed as a passive system below enclosed areas of the Brownfields
Property (excluding a large parking deck). Following installation, influence sampling will
be conducted and following, concurrent soil gas and indoor air sampling (IAS sampling
especially needed because this is a TCE impacted site). Following installation and
approval of occupancy, a minimum of 3 years of annual sampling will be conducted on
the property to determine VIMS effectiveness and if the system needs to become active.
If areas exist that qualify for final grade sampling, the EMP has committed to a separate
work plan for those. Further, there is an LUR requiring final grade sampling.