22001_S Graham Tower Decision Memorandum 20190806

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DECISION MEMORANDUM
DATE: August 6, 2019 FROM: Bill Schmithorst TO: S. Graham Tower BF File
RE: South Graham Tower 401 South Graham Street Charlotte, Mecklenburg County BF # 22001-18-060
Based on the following information, it has been determined that the above referenced site, whose intended use is for no uses other than retail, office, parking, high density residential, and, subject to DEQ’s prior written approval, other commercial uses, can be made suitable for such uses.
Introduction: The Brownfields Property is 0.673 acres and is currently used as a parking lot. The Brownfields Property is located in an urban area.
Redevelopment Plans: The PD plans to construct a high rise building for residential and commercial uses. The building will encompass nearly all of the entire parcel. Site History:
The parcel was occupied with residences and associated structures until approximately 1951, when the parcel was cleared and used for parking. The Brownfields Property remained undeveloped and has been used for parking for an undetermined amount of time.

Records indicate the historic presence of a cold storage facility on the south adjoining property. Records also indicate the historic presence of auto repair facilities on the south and southeast adjoining property. Groundwater contaminated with VOCs has been detected on the south adjoining parking lot at Mint and 2nd Streets. Based on the reports
submitted to the DEQ and a review of agency files, no indication of a release of
hazardous materials on the Brownfields Property was found in historical records. Potential Receptors: Potential receptors are: construction workers, on-site workers, and future residents. A
receptor survey was conducted and no sensitive receptors or water supply wells were
located within 1,500 feet of the Brownfields Property.
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Contaminated Media: DEQ has evaluated data collected from the following media at the subject property:
groundwater, soil, and soil gas. DEQ relies on the following data to base its conclusions regarding the subject property and its suitability for its intended reuse. Soil An environmental assessment of soil was conducted at the Brownfields Property in
September 2018. Eight soil samples were collected from eight soil borings and submitted to a laboratory for the analysis of volatile organic compounds (VOCs), semi volatile organic compounds (SVOCs) and RCRA metals. Laboratory results indicated four samples exceeded Residential PSRGs for arsenic, with the highest concentration at 3.0 mg/kg (B2). Laboratory results indicated that no other constituents analyzed exceeded
PSRGs.
Groundwater An environmental assessment of groundwater was conducted at the Brownfields Property in October 2017. Three temporary groundwater monitoring wells were installed and
sampled for VOCs, SVOCs, ammonia, and ethylene glycol. Laboratory results indicated that 1,2-dichloroethane and tetrachloroethylene were detected above 15A NCAC 2L.0202 North Carolina Groundwater Standards (NCAC 2L) in each temporary monitoring well. In addition, trichloroethylene was detected above NCAC 2L in a sample collected from monitoring well TW-2.

Soil Vapor Two soil vapor samples were collected at the Brownfields Property in September 2018 and submitted to a laboratory for the analysis of VOCs by EPA Method TO-15. Laboratory results indicated the detection of tetrachloroethylene in SG-1 at a
concentration of 420 ug/m3 above North Carolina Residential Vapor Intrusion Screening Level of 280 ug/m3. Risk Calculations Risk Calculations were performed using Excel worksheets provided by Sandy Mort,
NCDEQ Brownfields Toxicologist. For the purposes of looking at the highest possible risk, the highest concentrations were used in the risk analysis from groundwater, soil and soil gas samples. The risk calculations indicated the following based on available data, including the following media: groundwater, residual soil, and soil gas:

PRIMARY CALCULATORS
Receptor Pathway Carcinogenic Risk Hazard Index Risk exceeded?
Resident
Soil Combined Pathways 4.4E-06 8.6E-02 NO
Groundwater Combined Pathways* 4.5E-05 6.4E+00 YES
Non-Residential Worker
Soil Combined Pathways 1.0E-06 6.2E-03 NO
Groundwater 1.1E-05 1.5E+00 YES
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Combined Pathways*
Construction Worker Soil Combined Pathways 1.7E-07 6.5E-02 NO
VAPOR INTRUSION CALCULATORS
Receptor Pathway Carcinogenic
Risk
Hazard
Index
Risk
exceeded?
Resident
Groundwater to
Indoor Air 2.0E-05 4.1E+00 YES
Soil Gas to Indoor Air 8.8E-06 5.2E-01 NO
Non-Residential Worker
Groundwater to Indoor Air 4.4E-06 9.9E-01 NO
Soil Gas to Indoor Air 6.5E-07 4.1E-02 NO
Red shading LICR> 1E-04 or HI> 1.
LICR = Lifetime Incremental Cancer Risk HI = Hazard Index
Risk assessment results indicate risk exceedances from VOCs in groundwater to residents
and non-residential workers. In addition, risks from VOCs were exceeded for groundwater to indoor air for residents. In order to mitigate risks to onsite workers and construction workers, all construction work will be completed under an approved Environmental Management Plan. In addition, the Prospective Developer will install a
building vapor mitigation system to prevent unacceptable VOC levels from impacting the
interior of the building planned for construction. Arsenic concentrations were detected in soil above risk levels; however, these detections are comparable to concentrations found in naturally occurring soil in the area, as supported by environmental reports from multiple brownfields properties in the greater Charlotte area. The footprint of the
proposed building will encompass most of the property and little to no surface soil will be
exposed. Required Land Use Restrictions:
Based on the site-specific data provided to the Brownfield program, the site reuse is
suitable for the site as long as the PD/land owner complies with the agreed upon land use restrictions. A summary of the land use restrictions is provided below. 1. No use other than for high-density residential, retail, office, hotel, parking, restaurant,
and, subject to DEQ’s prior written approval, other commercial uses.
2. No groundwater use 3. No disturbing soil without DEQ approval or for landscape/mowing/pruning/repair of underground infrastructure (written notice to DEQ)/work for EMP. 4. Soil Import/Export.
5. No new buildings until PD demonstrates to the DEQ that indoor air is safe/no VI issues/VI protection installed. 6. No use of property for child care, adult care centers, or schools. 7. EMP
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8. Access to Brownfields Property for environmental assessment. 9. NBP reference in deed.
10. No contaminants on property except for de minimis amounts, fluid in vehicles, fuels for generators/equipment. 11. Ongoing maintenance of vapor mitigation systems. 12. Final grade soil sampling for RCRA metals, SVOCs, and VOCs will be conducted in exposed areas.
13. LURU submission January 1st