Project:
Cropsey
Location:
Brooklyn, NY
Date:
2009 to Current
General Services:
NYSDEC Spill Site Investigation and Remediation, Installation of SSD System

Hydro Tech was contacted when strong odors associate with gasoline vapors were detected in the basement of the new development prior to the building being occupied. The site was associated with an open NYSDEC Spill number which was supposedly rectified by others during site development. However, the strong odors entering into the basement were a red flag that something had gone array.

The New York State Department of Health (NYSDOH) through the New York State Department of Environmental Conservation (NYSDEC) the New York City Department of Health (NYCDOH) issued an order not to occupy the building so Hydro Tech had to work fast to get the problem fixed. We coordinated with all agencies to install a beneath each of the seven 3-story vacant residential buildings to prevent the soil vapor intrusion beneath the site and mitigate indoor air impacts. The systems were designed to provide a means of establishing a negative pressure field beneath the slab of the building in order to eliminate the potential vapor intrusion pathway between the vapor source (soil and groundwater) and the receptor (indoor air within the building interior). A quantitative pre-mitigation diagnostic testing exercise was performed in compliance with applicable sections of the Technical Guidance for Active Soil Depressurization Systems for Radon Reduction Techniques for Existing Detached Houses as published by the U.S. Environmental Protection Agency and applicable sections of the Guidance for Evaluating Soil Vapor Intrusion in the State of New York – October 2006 as published by the New York State Department of Health. The test successfully verified the likely full scale communication of SSDS suction vacuum beneath each building square footage. The SSDS was then installed beneath each building and SSDS operation was monitoring on a quarterly basis. The SSDS successfully prevented the sub-slab gasoline vapors from impacting the indoor air, which was revealed to contain petroleum-related compounds close to the background concentrations. Upon verifying this conclusion, the NYSDEC in consultation with NYSDOH and NYCDOH authorized the occupation of the seven new developments at this site.

Hydro Tech then performed a remedial investigation of the groundwater which consisted of the installation of both on-site and off-site monitoring wells. Based upon these results we designed a remedial action plan consisted of the injection of ORC and Chemox. These remedial products were injected using Hydro Tech’s fleet of geoprobes and injection equipment. The injection has been successful in reducing the levels of gasoline compounds in the groundwater and we are now in the monitoring phase of the project.