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Highly Vulnerable Aquifers of the Toronto & Region Source Protection Authority Highly Vulnerable Aquifers are aquifers that are more susceptible to contamination because of their location. In general, an HVA will consist of source granular aquifer materials (e.g. sand and/or gravel) or fractured rock that has a high permeability and is exposed near the ground surface with a relatively shallow water table. The approval of TRCA's Updated Assessment Report (UAR) in November of 2011 included an update to the HVA to include transport pathways (well clusters and aggregate extraction pits). The new HVA (AVI with a score of 6) replaces the old one which fulfilled the purposes of the Clean Water Act, 2006. |