Voluntary Cleanup Program Site: Staten Island, New York
Leggette, Brashears & Graham, Inc. (LBG) LBG is managing a site in Staten Island, NY which has entered into the NYSDEC Voluntary Cleanup Program (VCP). The site is also listed on the NYS Registry of Inactive Hazardous Waste Sites. The site is currently a strip mall with several buildings. One building had been occupied by a dry-cleaning facility for an indeterminate number of years. Site investigations beginning in 1994 had identified tetrachloroethene and its byproducts in groundwater and soil. Complicating the investigation are several other environmental spill sites including another dry cleaner adjacent to the site in question.
SCOPE OF SERVICES
LBG supervised the installation of site-wide multilevel cluster wells to define the groundwater plume both laterally and vertically which extends at least 380 feet downgradient and 90 feet deep. The wells have been sampled on a regular basis since 2005. LBG has developed a work plan to define the offsite plume beneath a residential neighborhood.
A soil-vapor intrusion investigation at the site revealed significant solvent concentrations in sub-slab vapor and indoor air. The indoor air levels in several areas of the building exceeded the Department of Health Guidance Values. Interim remedial measures designed and implemented by LBG included the installation of a vapor barrier on thebasement floor, adjustment of the building HVAC system and eliminating vapor pathways via basement sump pits.
Remedial strategies being developed for the site must address several environmental media: groundwater, soil, soil vapor and indoor air. A pilot-scale test of in situ reductive de-chlorination of groundwater is pending regulatory approval.