Junction Creek Remediation: Another Chapter in the Re-Greening of Sudbury, Ontario

摘要

The City of Greater Sudbury is a mining community in Northern Ontario,Canada, originally founded as a camp for railway workers in 1883. Years of environmentaldegradation from industry saddled the city with the reputation of having a barrenlandscape rife with pollution. With the 1970s came the advent of a paradigm shift in thearea. The City of Greater Sudbury initiated an unprecedented land reclamation program,and has since become a case study in commitment to environmental protection and rehabilitation.This paper tells the story of another chapter in the re-greening of Sudbury.Measuring approximately 20 km in length, Junction Creek flows through downtownSudbury, Ontario, and receives inputs from a variety of sources including industrialfacilities, urban runoff, and a downstream sewage treatment plant. Much of the creek isheavily engineered and forms a major part of Sudbury’s urban drainage system. In responseto the discovery of creosote impacts in the creek in 1999, several investigationswere conducted, including a Screening Level Risk Assessment (SLRA) identifyingbenzo(a)pyrene (B(a)P) as the main parameter of concern with respect to human health.The SLRA also developed cleanup targets for the creek bed. The remedial design includedconstruction of earthen dams and the use of bypass pumps to divert creek flowaround the work area. Excavated sediments were dewatered and sampled to determinedisposal requirements. A contingency plan consisting of confinement through the placementof geosynthetic clay liner (GCL) was developed in the event that impacts aboveSLRA criteria were encountered below the design excavation depth. A synergistic approachto site rehabilitation was adopted, in which the long-term goals of local interestgroups were incorporated into the design. The site access road was left in place for use bythe Rainbow Routes Association to complete the Sudbury leg of the Trans Canada Trail.Creek banks were restored with reduced slopes to minimize erosion and prevent slopefailure. To increase bed morphology and improve aquatic life habitat, riffles and poolswere constructed in the channel. A post-remediation monitoring program has been implemented,consisting of visual inspection, field monitoring and water sampling. Initialresults indicate that remediation was successful in addressing potential risk to receptors,and the placement of GCL has mitigated the risk of the migration of any additional potentiallyimpacted sediments.