Weekly Update Ending: June 04, 2010

National Grid’s Remediation Contractor continued with site remediation activities, which included the delivery of construction materials, imported backfill material (stone and common fill), as well as construction equipment and supplies. Decontamination commenced for the drill rig and equipment used in support of the Phase 1b pre-drill operations as part of the on-site 120-foot deep DNAPL Migration Barrier Wall installation in accordance with the NYSDEC-approved Field Change Request, FCR-06. In addition, the upper 65-foot Waterloo BarrierTM interlocking steel sheet piling was driven to the Site-Wide Cap subgrade elevation. Common fill material deliveries and final grading and cap installation activities continued to progress in the central, eastern, and southeastern parts of the Site. Temporary sheet piling continued to be decontaminated and staged for demobilization from 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, 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 May 31, 2010 through June 6, 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. On Wednesday, June 2, 2010 there were periods of elevated PM10 concentrations at Fixed Air Monitoring Site 3 (FAM 3) and Portable Air Monitoring Site 6 (PAM 6). These elevated concentrations were the result of high relative humidity; the elevated concentrations were reduced below the Action Limit after subtraction of background levels. Therefore, the site remained in the operational condition. 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 June 7, 2010 through June 11, 2010, Cap material deliveries along with final grading and Cap installation activities are scheduled to continue in the central and eastern parts of the Site.  Site preparations will continue for the installation of the 120-foot deep Composite DNAPL Migration Wall (Phase 3) in accordance with the NYSDEC-approved FCR-06. Site preparation activities will commence to support the Phase 1b Pre-Drill Activities waste management at Tent Position #10a and include the relocation and setup of the load-out stations (truck lining, scale, tarping, and decontamination pad). Management of the Phase 1b Pre-Drill activities waste stockpiled inside Tent Position #10a will commence and includes the off-site transport and disposal of impacted soils at approved and permitted disposal facilities. Temporary sheet piling will be demobilized from the Site.  Odor and dust suppression activities will be conducted, as necessary.  Work zone delineation, site maintenance activities, CAMP operation monitoring activities as well as noise and vibration monitoring activities will continue.