Upon completion of site remediation, the site will transition from active remediation to long-term operation and maintenance. The plant produced chlorine and other chemicals for the pulp and paper industry in Maine until the plant was closed in 2000. Mallinckrodt US LLC (Mallinckrodt), the successor to one of the former owners of the site, previously assumed responsibility for remediating and restoring the site. 
 
Remediation of the former HoltraChem plant site has been focused on the 60 acres of the 235-acre site where the manufacturing operations occurred during the 33 years the plant was in operation. A team of engineering firms with extensive experience in environmental remediation projects in Maine is working closely with Mallinckrodt US LLC and Maine DEP to complete the project. Remediation activities to date have included site investigation, monitoring, demolition activities, excavation of contaminated soil, construction of a groundwater treatment plant, replacements of caps on Landfills 3, 4, and 5, and monitoring the site daily.

Mallinckrodt began the process of dismantling buildings and infrastructure at the site in 2003 under oversight of the Maine DEP. Mallinckrodt also commissioned the design and construction of a new groundwater treatment plant (GWTP) which began operation in 2012. Agreement with the Maine DEP on the scope and sequencing of the site remediation was resolved in April 2014. One of the first tasks was rehabilitating a railroad spur that had fallen into disrepair, after its use as the major source for transport of materials to and from the plant.

As described under Project Cleanup / Regulatory Process, extensive sampling across the site provided information for the detailed design plans which were submitted to the Maine DEP. Upon approval of these designs, the plans were implemented to remediate the areas, confirmation sampling was conducted, and Closure Plans were submitted to Maine DEP for approval.

Site excavation work began in earnest in 2015, and the Maine DEP has approved the cleanup of nearly all the remedial areas. Remediation and restoration of the Landfill Ridge, was completed in 2015, Landfills 1 and 2, Landfills 3, 4, and 5, Southerly Stream, Northern Ditch, Southern Cove and the Scrap Metal Yard have all been completed. The last area of remediation, the Plant Area has detailed information available under Project Clean Up/Plant Area.