AECOM Report B&W - N - City of Guelph

City of Guelph2008 Annual ReportClosed Eastview Road Landfill Site4.6 Private Water Well QualitySix private wells (P5, P6, P7, P8, P12 and P13) and one landfill well (P10), all drawing their water from theshallow bedrock, were routinely sampled during 2008. P13 was added in to the private well monitoringprogram in 2005. This well is located on Eastview Road south of the landfill and Location 92. These wellswere sampled in June and November 2008, with the exception of P12.P12 was only sampled in June, as the owners could not be contacted in November. The water qualityresults are provided in Appendix D.There were no adverse effects from the landfill in the private wells. It should be noted that with the exceptionof the landfill water well, all of the private wells are located upgradient of the landfill site. Water quality ineach well is similar to previous years. Some water quality in the wells exhibit iron concentrations above theOntario Drinking Water Standards, which is attributed to natural groundwater conditions or possibly wellconstruction. These iron concentrations have been observed historically and also found in some of thebedrock monitoring wells. At wells P7 and P8, very minor increasing trends were observed for chloride fromthe early 1980s until the late 1990s. Since this time there has been a greater increase in chloride and to alesser extent sodium. At well P7, chloride has increased from 2.2 mg/L in 1984 to a high of 55.9 mg/L inJune 2004, remaining at these levels in 2005, but increasing to a high of 66 mg/L in June 2006. Although, in2007 a slight decrease was noted back down to 48 mg/L by November 2007, concentrations increased againto 71 mg/L in 2008.At well P8, chloride has increased from 6 mg/L in 1984 to a high of 34 mg/L in April 2003 but had seasonallystabilized at this level into 2005. Similar to P7, chloride also increased slightly again to a high of 48 mg/L inNovember 2006 at P8 and have remained similar into 2008. An overall similar increase has been noted atP12, since it was constructed in 1997. It should be noted that the chloride concentrations now observed atthese wells have become higher than concentrations found at well P5. P5 has exhibited chlorideconcentrations between 20 and 30 mg/L historically. In fact P7 has become similar to slightly higher thanlocation 50 chloride concentrations. Although there appears to be some increasing trend in chloride, theactual concentrations to date are 5 to 8 times lower than the ODWS for chloride of 250 mg/L. As well, it wasnoted that sodium had also shown some minor increases; however, the concentrations at all wells are below20 mg/L, with the exception of P7, which had sodium around 21 and 19 mg/L. This is over 10 times lowerthan the ODWS for sodium of 200 mg/L. Although trends are occurring, it should be noted that these wellsare located upgradient of the landfill site; it is therefore concluded that these trends are not related toleachate impacts.Further to the above, the water quality from well P13, added in 2005, was reviewed. Since the addition ofthis well, chloride concentrations have been observed to be elevated above background. Initial samplescollected in 2005 showed elevated chloride concentrations of 62 mg/L (July 2005) and 85 mg/L (November2005) in this well. Further in 2006, chloride concentrations continued to be elevated at 59 mg/L (June 2006)and 105 mg/L (November 2006) in this well. In 2007 and into 2008, although slightly lower, chloridecontinues to be elevated at between 71 and 80 mg/L. These concentrations are higher than those currentlyobserved at P7 and at location 50, although still much lower than the ODWS. Similarly, sodium is also(111414_2ra_apr29-09_city_of_guelph.doc) - 35 -