 Perimeter of the excavation showing the scalloped soil mix wall (SMW) and dewatering wellpoints |
Sevenson Environmental, National Grid’s Remediation Contractor, began soil excavation from within the temporary fabric structure (TFS) on Tuesday, February 3. A total of 4,843.80 tons of MGP-impacted soils were transported from the site to a thermal treatment facility in Southeast Pennsylvania. Sevenson’s survey contractor, Nelson & Pope, began to survey the base of the excavation to confirm that final excavation depths had been achieved. Once the final excavation depth was confirmed, backfilling of the excavation commenced. Sevenson continued mobilization of equipment, winterization of the water treatment plant, and delivery of backfill material.
Sevenson’s dewatering subcontractor, Griffin, continued operation the excavation dewatering system. Operation of the water treatment plant continued uninterrupted this past week. 1,213,305 gallons of water was treated from February 1 through February 7, bringing the total amount of treated water discharged from the site to 2,734,560 gallons.
 Survey stakes marking final excavation depth with loader bringing in backfill material |
Two-Week Outlook
Soil excavation and backfilling at the current location of the TFS is scheduled to be completed next week. The first move of the TFS and ancillary equipment is anticipated to begin late next week. Site grading, access road construction for on-site truck traffic, and site maintenance activities will continue in preparation for the relocation of the TFS. Continued winterization of the water treatment plant will be ongoing for the next week.
Sevenson’s dewatering subcontractor will continue the operation of the excavation dewatering system and begin installation of dewatering wellpoints at the next excavation location. Groundwater removal from the current excavation location will continue until backfilling of the excavation is completed and will commence at the next excavation footprint prior to the relocation of the TFS.
General hours of operation will continue to be Monday through Friday, 7:00 AM to 5:00 PM, and Saturdays, between 8:00 AM and 6:00 PM.