The former HoltraChem manufacturing facility was constructed in 1967 for the purpose of manufacturing chlorine and sodium hydroxide for use in the pulp and paper industry in Maine. Other products were also produced at the plant over the years before it ceased operation in 2000.  
The Plant Area at the Site, which is approximately 12 acres in size, is the area on which the former manufacturing processes took place. This area included numerous buildings and related infrastructure such as storage tanks and associated piping. The former “Cell Building” was where the majority of the manufacturing operations occurred, although there were other buildings for various ancillary production processes, maintenance, and materials storage. (The groundwater treatment plant, constructed in 2012, was not part of the former HoltraChem facility.) All of the former HoltraChem tanks and piping will be demolished upon final completion of the remediation and restoration at the Site.

 
The soils in and around the Plant Area have been investigated and some have been impacted by prior facility operations.

 
The original Corrective Measures Implementation Plan (CMIP) for the Plant Area was submitted in early 2017. Based on subsequent discussions between Maine DEP and Mallinckrodt, the remediation of the Plant Area has been separated into different phases of work. The Phase 1 design was submitted to Maine DEP in December 2017 and involved excavating impacted soils above the Soil Media Protection Standard and transporting those impacted soils offsite to a secure landfill. Maine DEP approved Phase 1 in January 2018 and the removal of impacted soils was completed in early 2019. Final backfill was completed in early summer 2019 and final restoration was completed in 2019.

 
Technical discussions were held with Maine DEP in December 2018 and design plans for the next phases of work were developed. The Phase 1A scope of work included excavation and restoration of the former Retort Area and pre-trenching in preparation for installation of a temporary sheet pile wall around the former Cell Building. Maine DEP issued a conditional approval for this work on July 12, 2019. The Cell Building scope of work was submitted to Maine DEP on August 7, 2019 and conditionally approved on September 16, 2019. This included the installation of a temporary sheet pile wall around the former Cell Building area and excavation and restoration of the former Cell Building area.

The Phase 1A and Cell Building Corrective Measures Implementation work began on July 26, 2019 and ended in September of 2020.

The next phase of work is the Plant Area CMIP – Concrete and Utility Removal. This was submitted to Maine DEP on July 2, 2020 and approved by Maine DEP on July 24, 2020. The objective of this work is to identify and remove obstructions (e.g. foundations and utilities) and prepare portions of the Plant Area for site clearance and future activities. This stage of work focuses on the portions of the Plant Area not previously excavated except for the Maintenance Building, Temporary Soil Stockpile Area 1, the railroad spurs, and the Chloropicrin Area. The Concrete and Utility removal work began in the fall of 2020 and continues into 2022. Additional work in the Plant Area is continuing throughout 2022.  The Catch Basin #6/Paved Sump CMIP was approved by Maine DEP on August 24,2022. This scope of work focuses on an area downgradient of the Cell Building and adjacent to the former Landfill 1 area. Additional plans to perform work in other Plant Area locations are being discussed and will be developed.