John Matthews Creek receives runoff from a watershed that is composed largely of historic urban development which predates current stormwater management practices. Historically, the deep, steeply sided V-shaped John Matthews Creek ravine has experienced slope instabilities due to creek erosion. The City engaged Associated Engineering to develop a management strategy to prevent future problems by controlling flows entering the ravine, and to mitigate a known erosion site identified in a previous study.
During the course of the assignment, and after a series of small storms, a rapidly advancing headcut formed a deeply incised trough approximately 100 m long and up to 10 m deep at the upstream end. The destabilization resulted in deposition of large amounts of sediment in the lowland fish bearing reaches and created long-term risks of block slope failures due to the deep cut.
Associated Engineering undertook conceptual planning, detailed design and construction phase services for the John Matthews Creek project including a flow diversion, and restoration of stable ravine and creek channel. The project involved significant challenges in site access, slope stabilization, and incorporating environmental features to mimic the natural morphology of the creek. Associated Engineering incorporated a high flow diversion pipe constructed within the restored valley bottom. Our approach allowed for balancing of environmentally sound design with civil engineering fundamentals. Specific design features included boulder weirs and vegetated riprap bank protection