Installation of the Waterloo Barrier along the north boundary.

National Grid’s Remediation Contractor continued with site remediation activities, which included the delivery of construction materials, imported backfill material (clean fill), construction equipment and supplies. Installation of the on-site Waterloo Barrier Wall continued to progress from east to west across the northern part of the site. In addition, the Waterloo Barrier Wall joints along the western part of the On-Site barrier wall were flushed and grouted. Record of construction surveys and construction stake-out surveys continued as site remediation activities progress. Final assembly and construction of the Tent Position #1 (southeast corner of the site) was completed and start-up operation of the vapor management system (VMS) commenced. Shallow Excavation remedial activities have commenced inside the temporary fabric enclosure at Tent Position # 1. Noise and vibration monitoring activities were conducted during the sheet piling operations of the on-site barrier wall (Waterloo DNAPL Migration Barrier Wall).

Personnel and equipment decontamination pads were utilized throughout site operations.  Further delineation of work zones (i.e., exclusion, decontamination, and support) continued, as required. Maintenance of the on-site gravel access roads, parking areas and material staging areas, the imported backfill material (i.e., clean fill) stockpile covers, and maintenance of the perimeter privacy screen continued.  Imported clean fill materials continued to be staged in the central part of the site and utilized as backfill material for the Tent Position #1 Shallow Excavation Area and for the construction of a stabilized working platform for the Waterloo DNAPL Migration Barrier Wall sheet piling rig.  Maintenance of 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.

Truck at egress from tent

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 April 27, 2009 through May 3, 2009, six fixed base CAMP units and one portable CAMP unit were in-use and measured TVOC and PM10. Fifteen-minute averages for TVOC and PM10 data remained in the Operational Condition. No elevated readings for TVOC or PM10 were reported for the monitoring period. Weekly Reports of the CAMP data can be found as a separate tab in the Weekly Report Archive section.

Foaming excavated material under the enclosure

For the week of May 4, 2009 through May 8, 2009, installation of the on-site Waterloo Barrier Wall will continue from east to west across the northern part of the site. In addition, the On-Site Waterloo Barrier Wall joints are scheduled to be flushed then grouted. Shallow Excavation remedial activities will continue within Tent Position # 1; where impacted material will be loaded out for off-site transport and disposal at the approved and permitted facilities. Excavations are backfilled with imported backfill materials. Work zone delineation and maintenance of the on-site gravel access roads, truck lining and tarping stations, personal and equipment decontamination pads, and the truck scale will continue. 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.