68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

COQUITLAM ULTRAVIOLET DISINFECTION FACILITY GEOTECHNICAL INVESTIGATION, DESIGN AND CONSTRUCTION CHALLENGES

Session: Problematic Soils and Ground Improvement III / Sols problématiques et amélioration du comportement III

Anthony Fuller, Golder Associates Ltd. (Canada)
Naresh Koirala, Golder Associates Ltd. (Canada)

Metro Vancouver (MV) manages and supplies drinking water for the 2.4 million residents in 21 municipalities of the Lower Mainland. In order to comply with new requirements under Health Canada’s Guidelines for Canadian Drinking Water Quality, in 2014, MV upgraded the treatment facilities in The City of Coquitlam with ultraviolet (UV) disinfection. The constraints at site for the new facility included adjacent slopes with a history of instability; the nearby Coquitlam River and an operating chlorination plant, as well as other infrastructure, in close proximity to the proposed facility. The geotechnical design and construction challenges presented by these constraints were significant. The final design had a smaller overall footprint compared to similar facilities, but deeper underground structure. Excavations up to 17 m in depth within a varved, non-plastic silt required careful design, extensive dewatering, and shoring. The paper discusses the geological and physical site conditions, the surface and subsurface investigation completed to characterize the soil and groundwater conditions and the geotechnical design and construction of the works.