INNOVATION March-April 2012

from 100 to 500 mg/L) to the more com- plex and more mineralized sodium bicar- bonate, and sodium-calcium-magnesium sulphate-bicarbonate waters (TDS rang- ing from 500 to >2000 mg/L). Locally, natural groundwater in the region may contain elevated concentrations of iron, manganese, barium, boron, sodium and fluoride that exceed the 2011 Guidelines for Canadian Drinking Water Quality. These general hydrochemical classes of groundwater quality do not indi- cate how groundwater evolved during infiltration of rain or snowmelt into the

Level Of Development

Vulnerability

I HEAVY

II MODERATE

III LIGHT

A

IA

IIA

IIIA

HIGH

B

IB

IIB

IIIB

MODERATE

C

IC

IIC

IIIC

LOW

Figure 3. Aquifer classification system from BC Ministry of Environment.

subsurface, nor the length of time it takes for such evolution, ie, the residence time and the rate of replenishment of groundwater to the buried-valley and bedrock aquifers. This information is needed for proper groundwater management in Northeastern BC and should also be a matter of future research. Similarly the degree of confine- ment of deep saline aquifers that might be used for water supply for fracking operations or wastewater disposal needs to be better established. For these general matters of groundwater management, the use of geochemical and isotopic tools will be necessary and is a task that is yet to begin.

12

10

8

6

Unconsolidated Bedrock

4

Number of Aquifers

2

0

IA IIA IIIA IB IIB IIIB IC IIC IIIC

Figure 4. Range of classified aquifers in the Peace River area. (Data source: Lowen Hydrogeology Consulting)

heavily used and highly vulnerable (IA) aquifers, to light develop- ment and low vulnerability (IIIC) aquifers (see Figure 3). The majority of the unconsolidated aquifers in the area are moderately developed and moderately vulnerable to contamina- tion, ie, IIB aquifers. The majority of bedrock aquifers range from IIB, moderately developed and moderately vulnerable, to IIIC lightly developed to low vulnerability. An aquifer classified as (B), ie, moderately vulnerable, may contain areas of both low and high vulnerability. Only five unconsolidated aquifers and one bedrock aquifer are considered highly vulnerable to contamination from surface (Figure 4). With regard to deep subsurface activities such as hydraulic fracturing, aquifer vulnerability will likely depend upon spatial proximity, the anisotropic properties of the bed- rock formations, stress relief fracturing and configuration of the groundwater flow systems. What is currently unknown about the bedrock valley aqui- fers is their hydraulic connectivity with neighbouring bedrock formations, particularly that connectivity which has arisen due to unloading after initial erosion, then sedimentary infilling, fol- lowed by isostatic rebound of the bedrock valleys after deglacia- tion. This should be a matter for future research. Shallow groundwater quality varies widely in the region and spatially within aquifers. Water types range from the calcium- magnesium bicarbonate and sodium bicarbonate types with low to moderate levels of total dissolved solids (TDS generally ranging

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