 Collecting a sample of treated water for permit required laboratory analysis |
Sevenson Environmental, National Grid’s Remediation Contractor, completed excavation within the third temporary fabric structure (TFS) location on Monday, March 16. Sevenson’s survey contractor, Nelson & Pope, completed the confirmation survey of the final excavation depths and backfilling of the excavation was completed. The ancillary equipment was removed from the TFS and the structure was moved to the fourth excavation location on Thursday, March 19. Placement of the air handling unit, dewatering pumps, and other ancillary equipment was completed on Friday, and excavation within the fourth TFS location began on Saturday, March 21. 159.38 tons of MGP-impacted soils were removed from the third TFS location and 1,090.72 tons of MGP-impacted soils from the fourth TFS location were transported from the site to a thermal treatment facility in Southeast Pennsylvania. A total of 4,023.33 tons of soil were removed from the third TFS location and the total amount of soil removed from the site to date is 22,408.53 tons.
Sevenson’s dewatering subcontractor, Griffin, continued operation of the excavation dewatering system through mid-week until backfilling operations were completed. The dewatering system was temporarily shut down while dewatering wellpoints were installed in advance of the move to the fifth TFS location. The headers, which had to be removed to move the TFS into position number 4, were reconnected to the wellpoints previously installed at the third and fourth TFS locations and dewatering of the fourth excavation location began on Friday. 1,868,600 gallons of water were treated this week, bringing the total amount of treated water discharged from the site to 10,408,100 gallons.
 Crew connecting piping from the dewatering pumps to the influent line to the water treatment plant |
Two-Week Outlook
Soil excavation at the current TFS location is scheduled to be completed late next week, with backfilling completed early the following week. Upon completion of backfilling, the fourth move of the TFS, reconnection of the ancillary equipment and excavation activities at the fifth TFS location is anticipated to begin late in the week. Access road re-alignment for on-site truck traffic, site grading, and site maintenance activities will continue in preparation for excavation of the fifth location. Backfill material will continue to be delivered to the site on an as-needed basis.
Sevenson’s dewatering subcontractor will disconnect the headers and remove the wellpoints installed at the third TFS location and reconnect the headers to the wellpoints installed at TFS positions 4 and 5, once the TFS is moved to the fifth location. Dewatering will begin prior to the commencement of excavation activities at the fifth excavation location. Groundwater removed from the excavation footprint will be pumped to the water treatment plant and discharged.
Sevenson, in conjunction with National Grid and the Suffolk County Water Authority (SCWA) has contracted Roadwork to tie-in approximately 75 feet of 12-inch water main from Bridge Street east along Long Island Avenue to the existing 12-inch water main. Work will continue west towards Main Street to tie-in the businesses located along Long Island Avenue to the new 12-inch water main as SCWA intends to retire the old, smaller diameter water mains from service. Work on the water mains is scheduled to be conducted during the general site operation hours beginning on Thursday, March 26 and completed by Friday, April 3. East-bound traffic will be detoured from Long Island Avenue to West Water Street during the installation of the water main. Once the water main is installed east of Bridge Street, one lane of Long Island Avenue from Main Street to Bridge Street will be closed with traffic controls in place to support 2-way traffic flow on Long Island Avenue.
Utility crews continue to work on the temporary re-location of overhead lines on northern Bridge Street to Long Island Avenue in preparation for the excavation of soils beneath Bridge Street. The line re-location is anticipated to be completed within the next two weeks.
National Grid contractors completed the repairs of the eastern-most section of the sewer line in Long Island Avenue on Tuesday, March 17.
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.