Bedrock aquifers of the SaanichVictoria area - PowerPoint PPT Presentation

Title: Bedrock aquifers of the SaanichVictoria area


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Bedrock aquifers of the Saanich-Victoria area
Based on a 2004 compilation by Sylvia Kenny for
the Ministry of Water, Land Air and Parks (now
Environment Ministry) http//www.env.gov.bc.ca/wa
t/aquifers/aquifers_crd/aquif_crd.html
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Saanich-Victoria bedrock geology
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Saanich Peninsula cross-section
Glacial and glacio-fluvial sediments
Karmutsen
Island Intrusive
Bonanza Gp.
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Major aquifers of the Saanich-Victoria area
from Kenny, 2004
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Island Intrusive
Aquifer 608 North Central Saanich Granitic
rocks (granodiorite) of the Island Intrusive
suite (Jurassic) 41 of wells in the area.
As water is transported within the aquifer
through joints and fractures, the productivity of
individual wells varies, depending on whether the
well intercepts these structures, and upon the
hydraulic connectivity of intercepted fractures
with other major fault systems. Previous
studies have found the fracture network within
the granodiorite can yield increasing quantities
of water with depth, with the greatest yield
occurring at depths between 40 and 80
metres. 62 of the wells are confined by
either clay or till, or both. Hardness is a
factor in some wells, and relatively high TDS is
also an issue. It is not clear if the high TDS
levels are derived from old deep water, or from
sea-water.
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Wark and Colquitz gneiss
Aquifer 680 Colwood, Langford, Esquimalt,
southern Saanich and Victoria Gneissic rocks of
the West Coast Crystalline Complex (mafic Wark
Gneiss and felsic Colquitz Gneiss) 31 of wells
in the area
The majority of well records describe the
bedrock of this aquifer as green, white and black
granite (!). other records describe the
occurrence of diorite and gabbro with feldspar
and quartz venation Most water-bearing
fractures are observed at depths of around 60
m 28 of the wells are confined by either clay
or till, or both. High iron and manganese levels
have been reported. Numerous contaminated sites
overly the aquifer, but no impact to water wells
has been documented.