Barrier wall construction continues 12/13

National Grid’s contractor and Project Team continued to construct the composite 120-foot deep dense non-aqueous phase liquid (DNAPL) Migration Barrier Wall (i.e., jet grouted barrier). The contractor continued Phase 3 remediation construction activities and general maintenance of the Site. The contractor continued Pre-Production Column quality control and quality assurance confirmatory drilling and core testing program. The contractor continued the management of jet grouting derived wastes within the Waste Management Facility (WMF). Jet grouting wastes were managed in accordance with NYSDEC approved procedures. The jet grouting contractor (JGC) and waste management and emergency response (WM/ER) contractor prepared submittals and scheduled activities for the project. Attached are representative photographs of the overall site.

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 December 12, 2011 through December 18, 2011, 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 week of December 19, 2011 through December 23, 2011, Phase 3 remediation construction activities consisting of the Pre-production Column quality control confirmatory tests are scheduled to be completed. The contractor is scheduled to complete the waste management inside the WMF that has been generated from the Pre-production Program which includes the off-site disposal at National Grid and NYSDEC approved and permitted facilities. The contractor will also conduct general maintenance activities and housekeeping at the Site, as necessary. The JGC and WM/ER Contractor will prepare the site and equipment for the winter holiday site shutdown. Dust suppression activities will be conducted, as necessary.