Demobilization operations

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). The jet grouting contractor and waste management contractor continued the decommissioning and demobilization of construction equipment and materials. The waste management (WM) contractor continued the management of jet grouting derived wastes within the Waste Management Facility (WMF). The WMF, which manages wastes (e.g., soils, cement mix and water) that are generated from jet grouting activities, is operated inside the tent with an active Vapor Management System (VMS). Jet grouting wastes were managed in accordance with NYSDEC approved procedures and wastes were disposed of off-site at a licensed and permitted disposal facility. In addition, the WM contractor commenced the disassembly of the temporary enclosure.

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 21, 2012 through May 27, 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.

For the holiday week of May 28, 2012 through June 1, 2012, the jet grouting contractor will continue the decommissioning and demobilization of the jet grouting equipment. The WM contractor will continue conducting general Site maintenance, decommissioning and demobilization of construction equipment and materials associated with the on-site WMF operation. Further, the WM contractor is scheduled to complete the load-out of the jet grouting derived wastes wastewater during the week. Dust suppression activities will be conducted, as necessary. The contractor will perform general maintenance activities and housekeeping at the Site, as necessary.