Presentation to the Community of Faulder, BC Faulder Groundwater Supply

Transcription

1 Presentation to the Community of Faulder, BC Faulder Groundwater Supply Presented by: Jacqueline Foley, M.Sc. Senior Hydrogeologist September 4, 2008

2 OUTLINE Meadow Valley Aquifer Overview Review of Previous (2005) Investigation 2008 Well Rehabilitation 2008 Age-Dating Analyses Questions

3 Study Area

4 Meadow Valley Aquifer

5 Meadow Valley Aquifer

6 Meadow Valley Aquifer

7

8 Meadow Valley Aquifer

9 2005 Preliminary Hydrogeological Investigation Water Balance Water Users Faulder Community Well Other Residents of Private Wells Estimated Agricultural Uses Total Current Estimated Withdrawal Proposed Private Development Total Proposed Estimated Withdrawal Estimated Withdrawal (m 3 /year) 400, , ,000 1,632, ,000 1,992,000

10 2005 Preliminary Hydrogeological Investigation Water Balance Groundwater Recharge Estimate (based on climate data) Groundwater Recharge Estimate (based on Darcy s Law) Average Recharge Estimated Proposed Withdrawals Water Balance 10,600,000 m 3 /year 9,500,000 m 3 /year 10,000,000 m 3 /year -2,000,000 m 3 /year +8,000,000 m 3 /year

11 2008 Investigations Well Rehabilitation Air-Burst Technology Water Level Analyses Age-Dating Tritium Helium Analyses Isotope Analyses

12 2008 Well Rehabilitation & Age Dating

13 1-Jan-05 1-Jan-06 1-Jan-07 1-Jan Dec-08 Depth to Water (mbgs) 2008 Well Rehabilitation & Age Dating Results 0 2 LEGEND MoE Obs Well MoE Obs Well Date

14 Declining water levels can be a result of: Climatic change i.e. low precipitation Current precipitation values are above the historical mean precipitation Other MoE observation wells completed in both confined and unconfined aquifers in the Okanagan Valley show yearly recharge, particularly in Increased groundwater withdrawals from the aquifer One additional groundwater withdrawal was noted and consists of approximately 60,000 m 3 /year (Acland Spring) in the north end of Meadow Valley. Change in the characteristics of the recharge area Thirsk Dam water levels were significantly lower in Thirsk Dam in 2003 (due to drought and increase irrigation demand) and in 2006/2007 (construction on dam).

15 2008 Age Dating Results Groundwater collected from the Gibbs Well and Community Well had similar isotope characteristics to surface water samples from both Trout Creek and Darke Creek. Isotope analyses indicated that winter and spring precipitation play a dominant role in the recharge of the aquifer. Tritium-Helium analyses indicated that the groundwater from the wells was between 5 years and 43 years old = modern water. Based on an average linear groundwater velocity ranging from 4x10-4 m/sec to 9x10-4 m/sec, a groundwater age of 5 to 43 years, and a maximum distance of 30 km to the edge of the watershed boundary, the recharge area was estimated to be between 5 km and 30 km from the Community Wells. Thirsk Dam is located approximately 25 km to the northwest of the Community Well.

16 Summary It can be inferred that low water levels at Thirsk Dam resulted in decreased recharge to the aquifer. Until approximately the end of June, water levels within the confined aquifer were declining. However, since July, water levels have show an increasing trend. There is sufficient recharge within the aquifer to support the estimated current needs for the Community of Faulder. The challenge is in accessing the water efficiently and effectively. Current withdrawals (2,060,000 m 3 /yr) from the aquifer only represent approximately 20% of the total flow (10,000,000 m 3 /yr) within the aquifer.

17 Water Conservation Recommendations Verify relationship between water levels at Thirsk Dam and the Community Well record water levels to assess trends Confirm Static Water Levels, Groundwater Flow Direction and Gradient - Wells should be surveyed Continue monitoring pumping and static water levels within the Community Well, Mearns Well and Gibbs Well. Secure a back-up water supply Drill a new well Acquire an existing well Additional field work Geophysics to assess the location of the maximum depth of the aquifer Monitoring wells farther up Darke Creek Valley and Trout Creek Valley

18 Questions?