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/wat/aquifers/aquifers_crd/aquif_crd.html. Saanich-Victoria bedrock geology.
Based on a 2004 compilation by Sylvia Kenny for the Ministry of Water, Land Air and Parks (now Environment Ministry)
Glacial and glacio-fluvial sediments
from Kenny, 2004
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.
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.