Weekly Update: March 01 - March 05, 2010

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Installation of 120 foot DNAPL Migration Barrier

National Grid’s Remediation Contractor continued with site remediation activities, which included the delivery of construction materials, imported backfill material (stone and common fill), and construction equipment and supplies.  Shallow Excavation Area remedial activities continued at Tent Position #13 with off-site transport and disposal of impacted soils at approved and permitted disposal facilities. Placement and compaction of imported clean backfill material continued within the Tent Position #13 Shallow Excavation Area. In addition, On-Site 120-foot deep DNAPL Migration Barrier Wall installations (Phase 1a) commenced at the Site.    National Grid’s consulting engineer conducted noise and vibration monitoring activities, as necessary.

Maintenance of the decontamination areas, work zones, on-site gravel access roads, parking areas and material staging areas, the imported backfill material (i.e., clean fill) stockpile covers, the perimeter privacy screen, 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 March 1, 2010 through March 7, 2010, six fixed base CAMP units and one portable CAMP unit 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.  No elevated TVOC or PM10 readings were reported for the weekly 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 March 8, 2010 through March 12, 2010, Tent Position #13 Shallow Excavation activities are scheduled to be completed with off-site transport and disposal of impacted soils at approved and permitted disposal facilities. Delivery of imported clean backfill material (stone and common fill) and backfill material placement and compaction are scheduled for completion inside Tent Position #13. Tent relocation activities from Tent Position #13 east to the next Tent Position are scheduled to commence. Tent relocation activities will include the temporary disassembly and staging of tent anchors and the vapor management system (VMS), temporary removal of the central panel, end panels and access doors, followed by the relocation of the two tent sections and replacement of the central panel, access doors, and end panels.  The temporary fabric enclosure supports, tent anchors, and VMS will be reset as the final phase of the tent position relocation.  In addition, Phase 1b On-Site 120-foot deep DNAPL Migration Barrier Wall mobilization activities are scheduled to commence in accordance with the NYSDEC-approved Field Change Request, FCR-06 (which is in the Major reports section of the Key Documents tab on this website).   Cap material deliveries and final grading and cap installation activities are scheduled to commence in the western part of the site.  Odor and dust suppression activities will be conducted, as necessary.  The NYSDEC-approved supplemental dust control measure, SoilTacTM, will be placed on non-traffic areas of the site, as necessary. Work zone delineation, site maintenance activities, and CAMP operation monitoring activities will continue.