Groundwater Geochemistry of the Nanaimo Group in the Yellow Point and Gabriola Island areas

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Groundwater Geochemistry of the Nanaimo Group in
the Yellow Point and Gabriola Island areas
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Environment Ministry evidence for elevated
fluoride levels
Malaspina well-water sampling program was
initiated in 2000
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Focused on Yellow Point and Gabriola Island areas
because they showed some particularly high
levels, and are close to Nanaimo.

• 100 wells at Yellow Point (2000)
• 75 wells on Gabriola (2001)

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gabriola map
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mudstone units sandstone units
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anion diagram
mudstone units sandstone units
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Proportion of water samples with fluoride levels
above the MAC (maximum acceptable
concentration)Yellow Point 13Gabriola 8
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RDN Landfill Observation well data

• Upper and lower samples at multi-piezo-meter sites

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landfill Ca
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representative n.g. g-waters
"Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website "Representative" Nanaimo Gp. water data from M. Env. website

Location type Depth pH Ca Mg Na HCO3 Cl Cond.
    m   mg/L mg/L mg/L mg/L mg/L uS/cm
Denman recharge 3 6.3 16 2.9 7.9 71 4.1 150
Gabriola recharge 11 6.8 7 1.0 32 80 5.4 183
Hornby recharge 6 7.3 29 6.7 40 171 20 368
Mayne recharge 24 7.3 24 6.7 12 110 6.9 229
N. Pender recharge 55 6.8 55 14.0 33 244 25 523
Saltspring recharge 30 7.8 25 2.6 37 156 11 315
Denman discharge 18 8.5 11 0.2 313 189 390 1500
Gabriola discharge 27 8.7 21 0.0 170 109 223 911
Hornby discharge 24 8.0 30 4.9 1270 238 1890 6100
Mayne discharge 23 8.7 21 5.3 854 287 960 4900
N. Pender discharge 50 8.0 58 4.6 815 287 1130 4260
Saltspring discharge 62 9.0 2 0.2 354 510 220 1600

Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands, Kohut, A, Foweraker, J and Hodge, W, Groundwater Resources of British Columbia, 9.13 Gulf Islands,
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CaCO3 CO2(g) H2O Ca2 2HCO3-
 

• According to the Le Chatelier principal, a
  decrease in the Ca content (because Ca is being
  removed from the water and adsorbed onto clays)
  will drive this reaction to the right, increasing
  the bicarbonate level, and resulting in a higher
  pH. This is base-exchange softening.

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owen drilling
Outcrop sampling at Yellow Point and Gabriola
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f-b for rocks
mudstone units sandstone units
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ph-f
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ca-f
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na-f
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so4-f
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cl-f
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b-f