Federal contaminated sites management, as has traditionally been undertaken as part of the Federal Contaminated Sites Action Plan program, can present some challenges to program efficiencies and resulting effective outcomes. Current approaches may be limited by funding, contracting and resource allocation constraints, which can result in large-scale complex contaminated site issues being treated and managed in a less effective silo fashion. The generation of more effective solutions and site management strategies requires consideration of the overall site setting as a whole, including all potential sources (both on-site and upgradient off-site); all current and future land uses and potential receptors and exposure pathways; all impacted media; all involved stakeholders; and, potential limits and constraints resulting from site uses, site users and existing infrastructure. Silo management, only considering specific issues, contaminants, or physical limits within a large-scale complex site in isolation of other influencing factors (i.e., potential risk arising from co-mingled on and off site plumes, analysis tailored to only assess one suite of contaminants of concern and not considering more which may be present), precludes the generation of more robust and synergistic solutions, resulting in less favourable outcomes for long-term site management and achievement of the overall program goals for all stakeholders involved. This presentation features a case study discussing an alternative holistic management approach to address a chlorinated solvent (DNAPL) plume in fractured bedrock at CFB Trenton. Due to the physical site setting, nature of the contaminants of concern, impacts arising from the contaminated plume and impacted media, co-mingling of potential sources, socioeconomic and political considerations and the involvement of various stakeholders, the most effective long-term management solution for the site will require consideration of multiple concurrent components. Considering the contaminated site holistically has allowed for the development of a stepwise site assessment program that has been tailored to inform the development of a detailed conceptual site model in tandem with a detailed quantitative risk assessment, groundwater treatment system specification, and future updated remedial options analysis. In this way, the identified potential risk to site users and receptors has been used to direct the subsequent supplemental field programs and investigations to address data gaps, which in turn has allowed for the prioritization of data and field programs to best support the finalization of the conceptual site model, confirmation of potential unacceptable risk to receptors and feasible remedial options. Considering the site contamination and potential adverse impacts as a whole will allow for more robust and favourable solutions for the long-term management of the site. Su-Kim Roy, Senior Project Manager and Environmental Engineer, Environmental Services Group, Stantec Consulting Limited Su-Kim Roy is a Senior Project Manager and Environmental Engineer in the Environmental Services group in Ottawa with over 20 years of experience in the environmental consulting field. Su-Kim is the Ontario Region Lead for Stantec Consulting Limited’s Federal Sector Team and has managed and been the primary environmental engineer or contaminant hydrogeologist on many projects for public sector clients including Public Services and Procurement Canada (National Capital and Ontario Regions), Defence Construction Canada, National Capital Commission, National Research Council, Natural Resources Canada, Canada Post and the City of Ottawa. Projects have included large multi-disciplinary teams providing technical expertise and support to complete Phase I/II/III environmental site assessments, data gap analysis, remediation programs, remedial options analysis, remediation design / specifications, tender and construction support, conceptual site models, risk assessments, and risk management plans at various federal sites across Canada.