1095 Southern Blvd, Bronx, NY 10459

Foxhurst

brownfield, CVOCs, VOCs, "Vapor Intrusion"

1095 Bronx LLC
Site Description[1] 
Location: The Site is located at 1095 Southern Blvd. in the Bronx. It is bordered by Southern Boulevard to the east, residential buildings immediately adjacent to the north and west, and a commercial building immediately adjacent to the south. Further east across Southern Boulevard are commercial properties. Site Features: The site is approximately 0.23 acres and is currently vacant and undeveloped. The previous on-site building was destroyed in a fire in 2008. Current Zoning/Uses: The property is currently vacant and undeveloped, following a fire in 2008 which destroyed the on-site building. The property is zoned R7-1 (residential district), with a C2-4 commercial overlay meaning that the property can be used for residential, commercial, or mixed (residential plus commercial) use. The proposed development is for a 40,000 square foot, 6-story office building, with below-grade parking. Historical Use: The property has historically been used for several commercial uses including, most recently, as a dry cleaning facility. It appears that chlorinated solvents detected on-site are related to the historical use of the site for dry cleaning. Site Geology and Hydrogeology: The elevation of the Subject Property is approximately 59 feet above mean sea level. The vicinity of the Site is characterized by metamorphosed sequence of bedrock known as the Manhattan Prong of the Hartland Formation. Bedrock has been identified at depths ranging from 12 to 24 feet below surface grade. The depth to groundwater beneath the Site is approximately 9 feet to 12 feet below ground surface. The groundwater flow direction beneath the Site is east.

Site Environmental Assessment
Nature and extent of contamination: The contaminants of concern are chlorinated solvents, consistent with the previous use of the site for dry cleaning. Tetrachloroethylene (PCE) and its breakdown products have been detected in soil, groundwater, and soil vapor Soil: Chlorinated Volatile Organic Compounds (VOCs) are present in soil predominantly near the eastern border of the site, in the depth range of 14 feet to 20 feet below surface grade. Concentrations of chlorinated VOCs exceed the Unrestricted Use Soil Cleanup Objectives (UUSCOs) in 4 of 14 on-site soil borings; all on the east of the site. In these borings, tetrachloroethylene (PCE) was detected as high as 1,200 parts per million (ppm); trichloroethylene (TCE) as high as 120 ppm; and cis-1,2-dichloroethene as high as 40 ppm. The UUSCOs for these contaminants, respectively, are: 1.3 ppm, 0.47 ppm, and 0.25 ppm. Low concentrations of petroleum-related VOCs and Semi-Volatile Organic Compounds (SVOCs) were detected on site, but at concentrations below the UUSCOs. Metals detected in soil at concentrations exceeding the UUSCO include: trivalent chromium at 33.8 ppm (UUSCO is 30 ppm); copper at 122 ppm (UUSCO is 50 ppm); lead at 357 ppm (UUSCO is 63 ppm); and zinc at 618 ppm (UUSCO is 109 ppm). Groundwater: The contaminants of concern in groundwater are chlorinated solvents. Similarly to soil, concentrations are highest in monitoring wells installed in the eastern portion of the site. Tetrachloroethene and its breakdown products were detected at levels exceeding NYSDEC Ambient Ground Water Quality Standards (AGWQS) in 9 of 11 on-site groundwater monitoring wells, in addition to one monitoring well installed in the sidewalk to the east of the site. Contaminants include: tetrachloroethene as high as 66,000 parts per billion (ppb) compared to the AGWQS of 5 ppb; trichloroethene as high as 17,000 ppb on-site and 52,000 ppb in an off-site well, compared to AGWQS of 5 ppb; cis-1,2-dichloroethene as high as 63,000 ppb compared to AGWQS of 5 ppb; and vinyl chloride detected as high as 7,920 ppb on-site and 13,000 ppb in an off-site well, compared to AGWQS of 2 ppb. Soil vapor: Soil vapor samples exhibited contaminants of concern at elevated levels. PCE was detected as high as 2,800 micrograms per cubic meter (ug/m3) and TCE as high as 280 ug/m3. Significant threat: The site presents a significant threat to public health and the environment due to the high concentrations of chlorinated volatile organic compounds (VOCs) in on-site soil, groundwater, and soil vapor; and due to the off-site migration of contaminants via groundwater.

Site Health Assessment
Contaminated groundwater at the site is not used for drinking or other purposes and the site is served by a public water supply that obtains water from a different source not affected by this contamination. Access to the site is restricted and contact with contaminated soil is unlikely unless persons dig below the ground surface. Volatile organic compounds in the groundwater may move into the soil vapor (air spaces within the soil), which in turn may move into the overlying buildings and affect indoor air quality. This process, which is similar to the movement of radon gas from the subsurface into the indoor air of buildings, is referred to as soil vapor intrusion. Because the site is vacant, the inhalation of site-related contaminants due to soil vapor intrusion does not represent current concern. The potential exists for the inhalation of site contaminants due to soil vapor intrusion for any future on-site redevelopment and occupancy. Furthermore, on-site soil vapor sampling indicates that off-site sampling of the adjacent structures is warranted.

Contaminants of Concern
Type of Waste Quantity of Waste
BROMOCHLOROMETHANE UNKNOWN
CHROMIUM UNKNOWN
DICHLOROETHYLENE UNKNOWN
LEAD UNKNOWN
MERCURY UNKNOWN
TETRACHLOROETHYLENE (PCE) UNKNOWN
TRICHLOROETHENE (TCE) UNKNOWN
VINYL CHLORIDE UNKNOWN
  1. DEC Environmental Site Remediation Database.  Site Name: "1095 Southern Blvd." and "1095 Southern Blvd.- Off-Site".

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