Loading...
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.