Hellings Tank Condition Assessment

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  • OfferingWater management
  • LocationNorth Delta, BC, Canada
  • ClientGreater Vancouver Water District (GVWD)
  • Timeframe2013
  • ServiceStudies and technical solutions

Seismic Withstand Capacity Study

Ausenco with sub-consultant Golder Associates (Golder) were retained by GVWD to assess the seismic withstand capacity and general service condition of the Hellings Tank, a concrete water tank designed and built in the early 1970s.

The scope of work included:

  • Geotechnical investigation, condition survey of the tank exterior/interior and its components as well as testing of concrete and interior paint samples.
  • The analytical part of the study focused on determining the tank components’ seismic demand using a 3D computer finite elements model and comparing the expected maximum seismic demands with the components’ existing capacities determined based on the calculated and tested capacity of the materials.
  • To address deficiencies in both the seismic withstand capacity and the tank’s general condition, upgrade schemes were proposed with associated cost estimates. The retrofit ideas were presented on drawings.
  • The work was summarised in a report that will form the basis for detailed design and construction in the future.

The upgraded tank performance is expected to be equivalent to what NBCC 2010 and BCBC 2012 define for post-disaster buildings, for an earthquake with 2% probability of exceedance in 50 years.