1. AQUIFER DESCRIPTION FOR ALDERGROVE CD AQUIFER (AQUIFER NO. 1192) 1.1 Conceptual Understanding of Hydrostratigraphy 1.1.1 Aquifer Extents The Aldergrove CD Aquifer is comprised of two westerly to northwesterly prograding bodies of glaciomarine outwash sands and gravels up to 50 meters thick, generally located between 30 and 70 meters elevation in the northeast part of the Township of Langley. The first sand body is recognized from 48th Avenue north, west of 276th Street and the second is observed further to the west, north of 72nd Avenue. The two sand deposits merge to the north. 1.1.2 Geologic Formation (Overlying Materials) The aquifer is generally overlain by glaciomarine silts and clays of the Fort Langley Formation, but can also be overlain by till in some locations. The aquifer is exposed locally in the cliffs along the Fraser River and the south side of Glen Valley. 1.1.3 Geologic Formation (Aquifer) The Aldergrove CD Aquifer is comprised of Fort Langley Formation sands and gravels interpreted to have been deposited as glaciomarine outwash. 1.1.4 Vulnerability Moderate – the aquifer is overlain by low permeability materials throughout the majority of its extent and at higher elevations, the aquifer is known to be unsaturated. However, as the aquifer is exposed along the Fraser River and Glen Valley, the vulnerability is considered moderate. 1.2 Conceptual Understanding of Flow Dynamics 1.2.1 Groundwater Levels and Flow Direction The permeable deposits of the Aldergrove CD Aquifer are exposed on both the cliffs of the Fraser River and the south side of Glen Valley, effectively allowing the aquifer to underdrain the local highlands and, as a result, the upper portions of the aquifer are known to be unsaturated over a sizable extent of the aquifer, with groundwater consistently observed below 40‐50 meters of elevation. As a result, depending on the elevation of the local ground surface, the depth to groundwater is considered to be Moderately Deep (30‐60 m), with regional groundwater flow direction towards the topographic lows to the north and northwest. 1.3 Recharge Recharge is generally from leakage from overlying confining units, sourced either from precipitation or from overlying watercourses (West Creek). Weak, local connections to the Aldergrove AB and Hopington AB Aquifers may also provide some minor amounts of recharge. 1.3.1 Potential for Hydraulic Connection The Aldergrove CD aquifer has weak hydraulic connections to other aquifers in the area (Aldergrove AB, Beaver River, and Hopington AB Aquifers). As a result of the general depth of the Aldergrove CD Aquifer, direct connections to overlying surface water features are not present. Seepage to underlying deposits or indirectly to watercourses where the Aldergrove CD Aquifer is exposed along various cliff and valley faces is possible. 1.4 Additional Information on Water Use and Management The Aldergrove CD Aquifer is utilized predominantly for private domestic water supply, though small scale use for irrigation and commericial/industrial purposes are possible. In comparison to other aquifers in the area, the Aldergrove CD Aquifer is more lightly utilized with the overall groundwater demand considered to be moderate based on the observed well density. 1.5 Additional Assessments or Management Actions: Given the relatively light degree of utilization of the aquifer and the fact that it is not being used for municipal water supply, management actions have not been identified for this aquifer. 1.6 Aquifer References Armstrong, J.E., 1980. Surficial Geology, Mission, British Columbia; Geological Survey of Canada, Map 1485A. Armstrong, J.E. 1981. Post‐Vashon Wisconsin Glaciation, Fraser Lowland, British Columbia; Geological Survey of Canada, Bulletin 322, 34 pages. Armstrong, J.E., 1984. Environmental and Engineering Applications of the Surficial Geology of the Fraser Lowland, British Columbia; Geological Survey of Canada, Paper 83‐23, 54 pages. Bernardinucci J. and K. Ronneseth, 2002. Guide to Using the BC Aquifer Classification Maps for the Protection and Management of Groundwater. BC Ministry of Water, Land and Air Protection, Water Air and Climate Change Branch, Water Protection Section. Carmichael, V., M. Wei and L. Ringman, 1995. Fraser Valley Groundwater Monitoring Final Report. Clague, J.J. (compiler), 1989. Quaternary geology of the Canadian Cordillera; Chapter 1 in Quaternary Geology of Canada and Greenland, R.J. Fulton (editor); Geological Survey of Canada, Geology of Canada, no.1, pages 17‐96. Clague, J.J., 1994. Quaternary Stratigraphy and History of South‐coastal British Columbia; in Geology and Geological hazards of the Vancouver Region, J.W. Monger (editor); Geological Survey of Canada, Bulletin 481, pages 181‐192. Clague, J.J., and J.L. Luternauer, 1982. Excursion 30A: Late Quaternary Sedimentary Environments, Southwestern British Columbia; International Association of Sedimentologists, Field Excursion Guidebook, Eleventh International Congress on Sedimentology, McMaster University, Hamilton, Ontario, Canada, August 22‐27, 1982, 167 pages. Clague, J.J., R.W. Matthewes, J.P. Guilbault, I. Hutchinson, B.D. Ricketts, 1997. Pre‐younger Dryan resurgence of the southwestern margin of the Cordilleran ice sheet, British Columbia, Canada; Boreas, Volume 26, pages 261‐278. Dakin, A., 1994. Fraser Lowland; in Chapter 9, Groundwater Resources of the Basins, Lowlands and Plains; in Groundwater Resources of British Columbia; B.C. Environment and Environment Canada, pages 9.1–9.30. Golder Associates Ltd. 2005. Comprehensive Groundwater Modelling Assignment. Submitted to the Township of Langley. 022‐1826/5000 Golder Associates Ltd. 2012. Groundwater Management Strategy: Protection, Management and Governance. Submitted to the Abbotsford/Mission Water and Sewer Commission. 10‐1435‐ 0013. Golder Associates Ltd. 2014. Assessment of Long‐Term Groundwater Availability for Domestic and Public Use and for Aquatic Habitats. Report Number: 1214350003‐005‐R‐Rev1. Submitted to the Township of Langley. September 30, 2014. Golder Associates Ltd., 2015. Monthly Groundwater Budget for the Hopington Aquifer – Salmon River Area, BC. British Columbia Water Science Series 2015‐01. Golder Associates Ltd., 2016. Refinement of Aquifer Mapping and Classification for Six Aquifers in the Township of Langley. Technical memorandum 1650437‐007‐TM‐Rev0 submitted to the BC Ministry of Environment, 29 July 2016. Kreye, R. and W. Wei. 1994. A proposed Aquifer Classification System for Groundwater Management in British Columbia. Ministry of Environment, Lands and Parks, Water Management Division, Province of British Columbia, Victoria. .