Landfill 3, 4, 5
Final Restoration Complete for Three Site Landfills
While much of the focus of the ongoing remediation of the former HoltraChem site in Orrington has been on the removal of two landfills, a key part of the overall site reclamation includes the installation of new protective covers on the three remaining landfills that will remain on the site as required by the Maine Department of Environmental Protection (DEP).
These new covers, also known as landfill caps, feature geosynthetic clay liners (GCL), which are designed to keep rainfall from reaching the material below the cover. The installation of these new caps, however, was more complicated than simply overlaying new liners and finishing it with new soil and plantings. The process is not unlike installing a new roof which involves removing the old shingles first and then cleaning up the roof in preparation for the new layer of shingles.
The capped landfills (Landfills 3, 4, and 5) were all used for brief periods of time while the chlor-alkali manufacturing plant was in operation. The landfills were installed between 1972 and 1978 and have been covered, maintained and monitored since that time. All have been closed since 1984. Combined, the landfills cover approximately three acres. As outlined in the remedial design Landfills 3 and 4 were capped together, and Landfill 5 received a separate cap.
RTD Enterprises, located in Madison, Maine was selected to install the geosynthetic liners. CDM Smith, the supervising construction firm overseeing the remediation, performed the majority of the rest of the work, including removal of the soil and existing caps, placement of base layers, installation of drainage layers, placement of soil and vegetation above the geosynthetic layer and vents. They also performed the final restoration and replanting of the area this summer.
While these landfills already had secure caps in place, Mallinckrodt US LLC (Mallinckrodt) agreed to install new covers in order to upgrade the covers to the current EPA regulatory requirements. It is a standard closure design to install new caps on existing landfills, this type of project has been implemented at landfills all over the United States.
This work was completed on schedule in 2017 with the areas stabilized and final vegetation restored.
Full copy is available at the Public repository located at: Orrington Town library - 15 School Street, Orrington, ME 04474
The Final Construction Closure report for the Landfill 3, 4, and 5 remediation was submitted to the Maine DEP on July 24, 2017. Maine DEP determined the report to be complete in a letter dated October 3, 2017.