Spraying MGP-impacted soils with an odor-neutralizing foam while conducting the “open air” excavation near the intersection of Bridge Street and Long Island Avenue

Sevenson Environmental, National Grid’s Remediation Contractor, completed the open excavation along Long Island Avenue and the excavation within the fifth temporary fabric structure (TFS) location on Thursday, April 9. Sevenson’s survey contractor, Nelson & Pope, completed the confirmation survey of the final excavation depths and backfilling of the excavations completed. Sevenson began breakdown of the air handling unit and other ancillary equipment on Thursday in preparation for the final move of the TFS. 2,203.27 tons of MGP-impacted soils were removed and transported from the site to a thermal treatment facility in Southern Pennsylvania. A total of 6,432.24 tons of soil were removed from the open excavation and the fifth TFS location; bringing the total amount of soil removed from the site to date to 32,202.14 tons.

Sevenson’s dewatering subcontractor, Griffin, continued operation the excavation dewatering system until backfilling operations were completed. The dewatering system was temporarily shut down on Thursday and disconnection of the headers from the dewatering wellpoints was begun. 1,097,991 gallons of water was treated this week, bringing the total amount of treated water discharged from the site to 14,494,801 gallons.

Conducting soil compaction tests on the backfill material placed within the limits of the “open air” excavation

Two-Week Outlook

Access road re-alignment for on-site truck traffic, site grading, and site maintenance activities will continue in preparation for excavation of the sixth location. The final move of the TFS to the sixth excavation location will take place the beginning of next week followed by reconnection of the air handling and carbon filtration units and other ancillary equipment. The excavation and transport of MGP-impacted soils within the sixth excavation location is scheduled to be completed late next week. Backfilling and confirmation survey of the final excavation depth will continue into the following week. Disconnection of the air handling unit and other ancillary equipment, including the breakdown of the TFS for eventual removal from the site will begin upon completion of backfilling activities. Backfill material will continue to be delivered to the site on an as-needed basis.

Sevenson’s dewatering subcontractor will reconnect the headers to the wellpoints installed at TFS position 5 to begin dewatering the excavation footprint of position 6. Dewatering will begin prior to the commencement of excavation activities at the sixth excavation location. Groundwater removed from the excavation footprint will be pumped to the water treatment plant and discharge.

Roadwork Construction and the utility crews have completed their respective work in Long Island Avenue and Bridge Street. The businesses and residences along Long Island Avenue are now tied-in to the new 12-inch water main and the former water mains are now retired. The underground utilities along the northern portion of Bridge Street have been temporarily relocated overhead to facilitate the excavation of soil beneath Bridge Street.

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.