Design Considerations for Groundwater Supplied Treatment Plants
Various factors need to be taken into account when designing a typical groundwater treatment plant in Ontario. Raw water from drilled wells is deemed by Ministry of the Environment (MOE) criteria to be groundwater, under the direct influence of surface water (GUDI). Such raw water may contain elevated levels of iron, manganese, colour, turbidity, taste/odours and microbiological contamination. It is affected more by the presence of dissolved substances than the presence of suspended solids. In accordance with the MOE requirements, the service agreement for a water treatment plant (WTP) stipulates that treated water produced by the facilities must be in compliance with the Technical Support for Ontario Drinking Water Standards, Objectives and Guidelines, June 2003, and the Drinking-Water Systems Regulation (170/03). The required treatment process for this raw water consists of coagulation, flocculation, sedimentation, and filtration (or equivalent treatment). It must achieve an overall performance that provides a minimum 3.0–log removal/inactivation of Giardia cysts and 4.0–log removal/inactivation of viruses.