Abstract The Randle Reef contaminated site, located in the southwest corner of Hamilton Harbour, is approximately 60 hectares in size. This site contains approximately 695,000 m3 of sediment contaminated with polycyclic aromatic hydrocarbons (PAHs) and metals. The complex Randle Reef sediment remediation project is finally coming to fruition after more than 30 years of study, discussion, collaborations, stakeholder consensus-building, and debate. This paper unravels the reasons behind the delays associated with implementing sediment management at the Randle Reef site. In-depth interviews with experts and professionals from organizations who are/were involved in the project were conducted to identify the nature of performance in five theme areas that are important for successful action namely: (1) participation of appropriate actors with common objectives; (2) funding and resources; (3) decision-making process; (4) research and technology development; and (5) public and political support. It is evident from this study that the hurdles to progress with addressing contaminated sediment sites involve technical, political, regulatory as well as social challenges. We offer potential solutions and a series of recommendations based on experts' first-hand experience with the management of such complex sites to inform how future remediation projects can overcome obstacles. This article has been made Open Access thanks to the kind support of CAWQ/ACQE (https://www.cawq.ca).