Continuation of decommissioning

National Grid’s contractor and Project Team completed the construction of the composite 120-foot deep dense non-aqueous phase liquid (DNAPL) Migration Barrier Wall (i.e., jet grouted barrier) in April 2012. The Jet Grouting Contractor (JGC) completed the decommissioning and demobilization of construction equipment, supplies and materials, while the Waste Management (WM) contractor continued this process. In addition, the WM contractor continued the decommissioning and disassembly of the Waste Management Facility (WMF) and Vapor Management System (VMS), temporary enclosure (tent) and air handling system (TIGG units). Two TIGG units have been decommissioned and demobilized from the site.

General maintenance and security activities also continued at the Site. Contractor demobilization of construction equipment and materials commenced. Maintenance of the imported backfill material (i.e., clean fill) stockpile covers and soil erosion and sediment control (SESC) measures continued. Odor and dust suppression activities were conducted, as necessary. National Grid’s consulting engineers continued to monitor the site activities with the community air monitoring program (CAMP) equipment.

During the period from May 28, 2012 through June 3, 2012, six fixed base CAMP units were in operation and measured total volatile organic compounds (TVOC) and particulates (PM10). Fifteen-minute averages for both TVOC and PM10 data remained in the Operational Condition. There were no elevated readings for TVOC or PM10 for this monitoring period. The Weekly Report that summarizes the CAMP data can be found as a separate tab in the Weekly Report Archive section. Since site intrusive work has been completed and as approved by NYSDEC, future CAMP operations will only measure PM10.

For the week of June 4, 2012 through June 8, 2012, the WM contractor will continue conducting general Site maintenance, decommissioning and demobilization of the temporary enclosure structure and VMS, construction equipment, supplies and materials associated with the on-site waste management operation. Further, the WM contractor is scheduled to complete the load-out of the remaining jet grouting derived wastewater during the week. Six fixed base CAMP units will be in operation to measure PM10. Dust suppression activities will be conducted, as necessary. The contractor will perform general maintenance activities and housekeeping at the Site, as necessary.