Review of remedial options for the Boat Harbour remediation project in Nova Scotia, Canada

Boat Harbour, located in Pictou County, Nova Scotia, Canada has been receiving industrial effluent wastewater from a nearby kraft pulp mill and chlor-alkali plant for over 50 years. Before receiving industrial effluent wastewater, the tidal estuary was culturally significant to the nearby Pictou Landing First Nation community. The tidal estuary was known for its medicinal, recreational, ceremonial, and subsistence functions. Formally a 140-ha natural tidal estuary, raw industrial wastewater was discharged into Boat Harbour beginning in 1967. Since inception, effluent treatment has undergone several upgrades in aeration capacity within the Boat Harbour Effluent Treatment Facility (BHETF) until the cessation of effluent discharge in 2020. Fifty years of industrial wastewater effluent discharge has resulted in widespread inorganic and organic contamination of unconsolidated sediments and surface water. Primary contaminants of concern include metals, dioxins and furans, and polycyclic aromatic hydrocarbons. The province of Nova Scotia has committed to the remediation of the BHETF, estimated to cost over $292 million CAD. The goal of the remediation program is to return Boat Harbour to its natural state as a tidal estuary to restore the historical, traditional, and recreational uses of the land. Remediation components and alternatives were rated based on technical (26%), environmental (24%), economic (22%), social (14%), and regulatory (14%) weighted indicators. Criteria weighting for the five indicator categories was determined collaboratively with stakeholders. For each design component of remediation, a list of approaches was developed along with subsequent alternatives. Approaches and alternatives were screened to eliminate options that were not technically feasible or did not align with remediation goals. The remaining feasible concepts underwent detailed review and evaluation to select Qualified Remedial Options to be shared with stakeholders for input.