Watermain Seismic Vulnerability Assessment & Mitigation Plan

Project Highlights

The District of Maple Ridge retained KWL to perform a seismic risk assessment on a 3 km section of watermain on River Road between Haney Bypass and 240 Street.  The soil surrounding the watermain may be susceptible to liquefaction and lateral movements in the event of an earthquake.

Recommended Improvements

KWL determined through hydraulic modelling that the watermain could be isolated during an emergency event without considerable impact on the surrounding system, provided that some improvements were made.  These included:

• Replacing a section of cast iron main with more resistant HDPE pipe
• Installing valve isolation chambers, which include seismic sensors, pressure sensors, emergency power supply and thrust restraint
• Developing an emergency response plan, including fire protection, for areas affected by the isolated main
• Installing expansion joints to allow flexibility where watermain crosses Kanaka Creek, and
• Upgrading watermain looping in the adjacent area.

Options to fully protect the watermain were also considered, but the isolation option was chosen as it was considered to be the most cost-effective and viable solution.