Ground Improvements for Annacis Wastewater Treatment Plant Expansion

A. Port

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: GROUND IMPROVEMENT - I

ABSTRACT: The Annacis Island Wastewater Treatment Plant (AIWWTP) is owned and operated by Metro Vancouver in the Lower Mainland of British Columbia. To meet increasing demand requirements, the Stage 5 Phase 1 Expansion began in 2014. To reduce seismic induced displacements and to meet post-disaster operational requirements, densification of loose to compact sand was required beneath and around new structures. Ground improvement consisted of densifying an area of approximately 43,000 square meters to a depth of 32 m through the installation of 5,500 stone columns. Settlement of adjacent structures during stone column installation was a key concern. Settlement of the site and adjacent structures was monitored in real time using an automated survey system which monitored over 400 optical prisms every 4 hours. The system provided high quality data showing soil settlement and horizontal displacement as a result of stone column installation. Settlement of sensitive structures in close proximity to the densification areas was successfully reduced through construction of 420 m of Cutter Soil Mixing (CSM) double-wall to 30 m depth. Prior to CSM production, a trial wall was constructed and instrumented to assess the effectiveness of the CSM wall in reducing settlement and horizontal movement.

RÉSUMÉ: du Lower Mainland de Colombie-Britannique. Afin de répondre à une demande croissante, la phase 1 de de terre, on a du renforcer et densifier le sable meuble à dense situé autour de et sous les nouvelles structures. Des renforcer et densifier le terrain ballastées. Le tassement des bâtiments et structures annexes durant la densification est un souci majeur. Le tassement du site et des bâtiments annexes est enregistré en temps réel grâce à un système automatique de collection de données qui surveille plus de 400 prismes optiques toutes les quatre heures. Ce système fournit des données fiables montrant les mouvements horizontaux et la compaction du sol directement liés . sensibles situées à proximité immédiate des zones de compaction a été réduit via la Cutter Soil Mixing (CSM) de 420 mètres de long et de 30 mètres de profondeur. Avant la production de CSM, fut construite et équipée mur à réduire les mouvements horizontaux et le tassement du sol.

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Cite this article:
A. Port (2016) Ground Improvements for Annacis Wastewater Treatment Plant Expansion in GEO2016. Ottawa, Ontario: Canadian Geotechnical Society.

@article{3804_0707193757,author = A. Port,title = Ground Improvements for Annacis Wastewater Treatment Plant Expansion,year = 2016}