Temporary Fabric Enclosure being erected at Excavation Area 1

National Grid’s Remediation Contractor continued with site remediation activities, which included the delivery of construction materials, imported gravel for access road expansion, temporary enclosure (tent) air handling system duct work, tent structural members and hardware, additional temporary steel sheeting, and additional earthwork equipment and supplies. Pre-trenching and installation of the on-site Waterloo Barrier Wall continued in the northeast corner of the site and progressed in an east to west direction across the northern part of the Site. Record of construction surveys of the former perimeter utility cut and cap excavations were conducted at the northwestern perimeter of the site. The assembly and construction of the temporary fabric enclosure (tent) framing and ribbing continued at the Site (Tent Position #1). In addition, temporary sheets were driven along the western and northern legs of the northern half of the Tent Position # 1 footprint. Noise and vibration monitoring activities were conducted during the sheet piling operations of the on-site barrier wall (Waterloo DNAPL Migration Barrier Wall) and temporary steel sheeting.

Personnel and equipment decontamination pads were utilized throughout the site operations.  Further delineation of work zones (i.e., exclusion, decontamination, and support) continued, as required. Maintenance and expansion of the interior gravel access roads, parking areas, staging area, and upgrade of the imported backfill material (i.e., clean fill) stockpile covers continued.  Imported clean fill materials were removed from the stockpile located at the staging area in the southwest corner and used as backfill.  Imported clean fill material was delivered and staged in the central part of the site for use as backfill material. 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.

Photographs of the Waterloo Barrier Wall installation in the northern part of the On-Site Area and temporary fabric enclosure erection at Tent Position # 1 are provided on this page.

Installing the Waterloo Barrier along north side of site

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 March 30, 2009 through April 03, 2009, sixed 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. On March 30, 2009 elevated dust concentrations were reported during the sheet pile installations in the vicinity of FAM-3. Additional dust suppression measures were instituted and the reported dust concentrations quickly dropped and the site remained in the Operational Condition. Weekly Reports of the CAMP data can be found as a separate tab in the Weekly Report Archive section.

For the week of April 6, 2009 through April 10, 2009, installation of the on-site Waterloo Barrier Wall will continue from east to west across the northern part of the Site. Work activities will continue at the tunnel entrance to close off (i.e., plug) the southern end.  Erection of the temporary fabric enclosure base frame, structural members, and fabric panels will continue. Installation of the vapor management system (VMS) will commence. The on-site gravel access roads and personal and equipment decontamination pads will be further upgraded. 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.