National Grid’s Remediation Contractor continued with site preparation activities, which included the delivery of construction materials, additional equipment and supplies. The two foot thick Site Wide Cap and perimeter utility cut and cap excavations continued along the southern and northern parts of the site. Utilities exposed during the operation were identified and marked to be subsequently surveyed and decommissioned, as appropriate. The excavated materials were transported off-site for disposal at approved and licensed disposal facilities. Demolition of concrete continued at the northern and southern parts of the site. The demolished concrete was relocated to a staging area in the southwest corner of the site. Noise and vibration monitoring activities were conducted during the concrete demolition activities.

The personnel and equipment decontamination pads were utilized throughout the site operations.  Further delineation of work zones (i.e., exclusion, decontamination, and support) continued, as necessary. Maintenance of the interior access roads, parking areas, staging area, and upgrade of the imported backfill material (i.e., clean fill) stockpile covers continued.  Fill materials were removed from the imported fill material staging area located in the northwest corner of the Site and used as backfill for the perimeter cut and cap excavations. After the imported fill material was removed, the former staging area was restored as a construction support zone and parking area.  Additional DNAPL migration barrier Waterlootm steel sheet piles were delivered and staged in the northwest corner of the site. Maintenance of the site engineering controls and soil erosion and sediment control (SESC) measures continued. Odor and dust suppression activities were conducted as necessary. National Grid’s consulting engineer continued to monitor the site activities with the fixed base community air monitoring program (CAMP) equipment.

CAMP data is reviewed and compared to specific NYSDEC/NYSDOH approved criteria, known as “Action Limits.” As a result of this evaluation process, site conditions are categorized into two categories, “Operational Condition” and “Action Condition.” The “Operational Condition” is applicable when the data is below the “Action Limits”, and means that normal operations can continue. The “Action Condition” occurs when one or more of the fifteen minute average measurements for Dust (PM10), Total Volatile Organic Compounds (TVOC), Naphthalene or Odor Intensity are greater than the background or upwind measurement by the specified “Action Limits.” Reaching an Action Level requires corrective action or stopping work until the condition is addressed or abates. During the period from February 23, 2009 through March 1, 2009, six fixed base CAMP units and two portable CAMP units were in-use and measured TVOC and PM10. Fifteen-minute averages for TVOC and PM10 data remained in Operational Condition. No elevated readings for TVOC or PM10 were reported during the weekly monitoring period. Weekly Reports of the CAMP data can be found as a separate tab in the Weekly Report Archive section.

For the week of March 2, 2009 through March 6, 2009, perimeter utility cut and cap excavation activities are scheduled to continue along the southern and northern parts of the site with off-site transport and disposal of excavated impacted material at an approved and licensed disposal facility. In addition, pre-trenching activities for the on-site DNAPL migration barrier wall will be conducted concurrently with the northern perimeter utility cut and cap activities. Utilities exposed during the excavation activities will be identified, surveyed, and decommissioned, as appropriate. Concrete pads along the northern and southern part of site will be demolished. Demolished concrete selected for reuse will be consolidated in the southwestern area of the Site for future crushing and reuse in accordance with the applicable NYSDEC approvals. National Grid’s consulting engineer will continue to monitor the site activities with noise and vibration monitoring equipment. Odor and dust suppression activities will be conducted as necessary. National Grid’s consulting engineer will continue to monitor the site activities with CAMP equipment.