Design Considerations for Groundwater Supplied Treatment Plants

Abstract

Various factors need to be taken into account when designing a typical groundwatertreatment plant in Ontario. Raw water from drilled wells is deemed by Ministry of theEnvironment (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 dissolvedsubstances than the presence of suspended solids.In accordance with the MOE requirements, the service agreement for a water treatmentplant (WTP) stipulates that treated water produced by the facilities must be in compliance withthe Technical Support for Ontario Drinking Water Standards, Objectives and Guidelines, June2003, and the Drinking-Water Systems Regulation (170/03). The required treatment process forthis raw water consists of coagulation, flocculation, sedimentation, and filtration (or equivalenttreatment). It must achieve an overall performance that provides a minimum 3.0–logremoval/inactivation of Giardia cysts and 4.0–log removal/inactivation of viruses.