Weekly Update Ending: April 15, 2011

National Grid’s Remediation Contractor and Project Team continued to plan for the composite 120-foot deep dense non-aqueous phase liquid (DNAPL) Migration Barrier Wall (i.e., jet grouted barrier) installation. The Remediation Contractor performed general maintenance activities and housekeeping at the Site. No intrusive remediation construction activities were conducted at the Site. National Grid participated in the April 12, 2011 Community Board # 14 update meeting.

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 April 11, 2011 through April 17, 2011, six fixed base CAMP units were in-use 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 April 18, 2011 through April 22, 2011, perimeter privacy screen and silt-fence repairs, general site maintenance and housekeeping are scheduled to be performed. No intrusive remediation construction activities are scheduled at the Site. Dust suppression activities will be conducted, as necessary. CAMP operation monitoring activities will continue. The specialty contractor procurement for the 120-foot deep Composite DNAPL Migration Barrier Wall Installation is scheduled to continue.