Sam Ziemann From - Region of Waterloo

July 23, 2010Lisa Lachuta, P.Eng.Page 4 of 7Reference: Technical Memorandum A1 –Strange Street Well Field Water Quality Assessmentexceeding the ODWS Aesthetic Objective (AO) of 250 mg/L were observed at formerProduction Wells K12 and K17, as well as Production Well K10A. A similar upwardtrend was noted in the concentration of sodium at each of the production wells,suggesting that winter road salt activities is the likely source of the impacts. Bothhistoric (Stantec, 2000) and current (May 2010) water quality analysis at monitoringwells throughout the well field found elevated chloride and sodium in select wells. Inparticular, monitoring wells OW1-82, SS13-99 and SS08-99 indicated concentrationsthat are approaching or exceeding the ODWS. All the residential wells sampled (RW1,RW2 and RW3) exhibited elevated sodium and chloride concentrations.The monitoring and production wells on the western edge of the well field typically havelower concentrations of chloride and sodium than those wells further east. In particular,wells east of Westmount Road exhibit elevated sodium and chloride. The exceptions tothis were SS08-99, RW1, RW2 and RW3, where chloride and sodium were observed tobe elevated during the May 2010 sampling, and OW4B-46, in the vicinity of K11A andK13, where the ODWS was exceeded for both sodium and chloride during the 1999sampling event (Stantec, 2000).IRONIron concentrations found within production wells have varied historically, but aretypically below the ODWS AO of 0.3 mg/L (Figure 2). Iron levels within raw waterobtained from Production Well K10/K10A have been the most variable, with occasionalspikes in the data resulting in exceedances of the ODWS. Water quality resultsobtained from monitoring wells in the 2010 sampling event found elevated ironconcentrations in all wells (8.92 mg/L to 0.035 mg/L), as indicated on Figure 1. Duringthe 1999 sampling event (Stantec, 2000), the ODWS was exceeded in monitoring wellsnear all the currently active production wells. Elevated iron is naturally found ingroundwater extracted from this aquifer, and is not the result of anthropogenic activity.The Region is currently planning for the installation of a water treatment plant to treatthe elevated iron found in the water obtained from the Strange Street Well Fieldproduction wells.MANGANESEWithin the Strange Street production wells, manganese has historically been near orabove the ODWS AO of 0.05 mg/L (Figure 2). A slight increasing trend was noted forall production wells, with Production Wells K10/K10A and K11 typically having thehighest levels of manganese. Production Well K12 also exhibited elevated levels ofmanganese while in operation, typically above 0.4 mg/L.Within monitoring wells sampled as part of the 2010 monitoring program, elevatedmanganese was observed to be above the ODWS AO in all monitoring wells east ofProduction Wells K18/K19. This is consistent with the 1999 water quality results, whichfound elevated manganese in many of the wells that were sampled throughout the wellfield. Elevated manganese is naturally found in groundwater extracted from this supplyaquifer, and is not the result of anthropogenic activity. The Region is currently planningfor the installation of a water treatment plant to treat the elevated manganese found inthe water obtained from the Strange Street Well Field production wells.