Mayor's Report - March 2005


2004 BELCARRA AQUIFER STUDY

In April 2002, the Environmental Affairs Committee hosted the first Belcarra Aquifer Forum to raise awareness about groundwater. The regional Hydrogeologist for WLAP was the keynote presenter at the forum, and provided an excellent overview of the “workings” of groundwater movement and wells. It’s worth reviewing the Belcarra Aquifer Forum material posted here on this website.

Mayor Ralph Drew

In June 2004, the Environmental Affairs Committee hosted the second Belcarra Aquifer Forum to introduce a multifaceted approach to the development of a potable water supply strategy for Belcarra. The first facet of the strategy focuses on the hydrological aspects of the groundwater supply in Belcarra. (Other facets include: community education, conservation, protection from contamination, etc.) To pursue this strategy, Council funded a study by SFU student Melissa Holt under the direction of Dr. Diana Allen, Ph.D., Professor of Hydrogeology at SFU. (Dr. Allen has previously conducted groundwater studies for Hornby Island and other similar locations.)

The first phase of the study, conducted during the summer of 2004, focused on developing a conceptual model of the Belcarra Aquifer and the associated subsurface hydrogeology, and involved the following aspects:


  • Review existing reports, aerial photographs, surface and geological maps.
  • Obtain all available water well logs for existing and abandoned wells.
  • Survey the residents of Belcarra to obtain ‘missing’ information, determine the number and status of water wells (in use, abandoned, decommissioned, etc.), request water use information to estimate water consumption, and request sampling frequency and results, etc.
  • Prepare drawings showing well locations, the status of each well, and the anticipated location, size and flow direction for the identified aquifers.
  • Create cross sections showing the subsurface stratigraphy and anticipated groundwater regimes.
  • Determine the catchment area and precipitation infiltration for each identified aquifer.
  • Determine the aquifers from which the water wells draw water.
  • Estimate potential groundwater yields for the identified aquifers.

On March 7th Melissa Holt presented the results of the 2004 Belcarra Aquifer Study Adobe Acrobat Format (4.8 MB) to a joint meeting of Belcarra Council and the Environmental Affairs Committee. Some of the conclusions from the report are as follows:

  • The Belcarra Aquifer is an unconfined, fractured bedrock aquifer overlain by unweathered glacial till and soil, and is classified as a Type 1A aquifer by BCWLAP.
  • There are three main geological units in the Belcarra area: topsoil – developed by soil-forming processes (weathering, plant growth, biological activity) from the underlying till and bedrock; unweathered glacial till; and bedrock.
  • Bedrock is overlain by 5-20m of glacial till variably composed of silt, sand, clay and gravel, and 0-5m of topsoil.
  • Based on measured heads in wells, recharge generally occurs in areas of elevation above approximately 30-60m elevation. Discharge occurs in regions of elevation below 30-60m. Subsurface flow is radial from areas of recharge to areas of lower elevation.
  • Groundwater can be generally classified as a bicarbonate to bicarbonate-chloride-sulfate type water in terms of its anion chemistry, and as a calcium-magnesium to a sodium-calcium type water in terms of its cation chemistry. (The water quality is considered to be “very good”.)
  • Comparison with older chemistry data shows that the overall relative concentrations have not changed appreciably over time in these wells.
  • The total annual precipitation for Belcarra is calculated to be 2331 mm, and the total area of recharge for Belcarra is roughly 8.79 km2.
  • The hydrograph method of recharge estimates recharge to the aquifer on the order of 114 mm/year using an unconfined storativity of 0.01. The amount of recharge estimated from this method is approximately 4.9% of the total annual precipitation to Belcarra.
  • Recharge to the Belcarra Aquifer is estimated at 10x105 m3/yr. With estimates of consumption rates in the Village of Belcarra around 148,000 m3/yr, the village is using approximately 14.8% of the annual recharge to the aquifer. (The current usage is considered to be “sustainable”.)

RALPH DREW
MAYOR


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Village of Belcarra
4084 Bedwell Bay Road
Belcarra, BCCANADA
V3H 4P8

E-mail: belcarra@belcarra.ca
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