Weekly Update Ending: May 14, 2010

Cap Installation

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. Off-set Tent Position # 10 (Tent Position # 10a) continued to operate 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. The pre-drill material management system and bentonite slurry mixing system continue to operate in support of the Phase 1b pre-drill program.  Phase 1b pre-drill equipment start-up activities and initial pre-drill operations continued along the east end of the 120-foot deep DNAPL Migration Barrier Wall. Common fill material deliveries and final grading and cap installation activities continued to progress in the south-central and north-east parts toward the south-east area of the Site. Temporary sheet piling installation along the western side of the projected Tent Position #15 was completed. 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 10, 2010 through May 16, 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 May 17, 2010 through May 21, 2010, Tent Position # 10a will continue to be operated in support of the Phase 1b pre-drill activities. Phase 1b On-Site 120-foot deep DNAPL Migration Barrier Wall pre-drilling operations (relief/tool shafts) will continue and the sheet pile driving will commence in accordance with the NYSDEC-approved FCR-06.  Cap material deliveries along with final grading and cap installation activities are scheduled to continue in the central and eastern parts of 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.