Preload Effect on Groundwater Levels

A significant portion of the City’s lands are within the floodplain and natural springs are present in the highlands. Although the water table fluctuates throughout the year and associated seasons and rainfall events, the water table is relatively high. Additionally, the soils within the City contain areas of highly compressible silts, clays and peats. The high water table coupled with the soil conditions leads to an increased potential for groundwater risks.

The City recently undertook a groundwater study and built a groundwater model to evaluate and classify the potential groundwater risks associated with preloading. Additional groundwater data will be inputted into the model yearly.

Figure 15 below outlines the various risk levels in the southern part of the City, and the City has developed a list of additional information that may be requested of developers, depending on the risk area.

This model can also be utilized by developers by uploading site-specific information for their proposed development to assess the impacts on the groundwater (which would be completed by the City’s consultant as a cost). This may help provide additional information on the level of mitigation needed for a site to ensure it does not impact surrounding properties or have unintended consequences.

For more information, please contact the Engineering Department at

A map showing the different risk levels for preloading throughout Pitt Meadows

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