AECOM Report B&W - N - City of Guelph

City of Guelph2008 Annual ReportClosed Eastview Road Landfill SiteAs stated earlier, data has now been collected for just over one year at the new bedrock monitors. Thispreliminary data continues to suggest that groundwater flow in the shallow bedrock is towards the landfillfrom 37-I. This is best demonstrated by the water level elevations at monitors 94-I and 95-I. Monitor 94-I islocated between the landfill and 37-I, whereas 95-I (near the former office) is located between 37-I and 50-I.Based on these monitors, groundwater flow is interpreted to be back towards the landfill and slightlysoutherly towards monitor 50-I. Further, water quality results for chloride indicate that 94-I has similar verylow concentrations as the other bedrock monitors at the site (generally around 1 mg/L), whereas, 95-I hasconcentrations that are slightly higher than observed at 50-I. These observed concentrations appear tosupport the interpreted groundwater flow and to verify that the chloride at 37-I does not appear to be landfillrelated, as the monitor closest to the landfill has the lowest concentrations. Further, monitor 95-I has slightlyhigher concentrations than 50-I and is interpreted to be downgradient and closer to 37-I. Therefore, thepreliminary data from the new locations continue to indicate that there is another upgradient source for theelevated chloride at 37-I.In conclusion, there is no indication of leachate impacts in the bedrock groundwater in the area of the landfillbased on chloride alone, although elevated and increasing chloride concentrations in some bedrock monitorswill continue to be assessed in the future. As well, preliminary data continues to suggest that the increasingchloride at 37-I is not landfill related and most likely from an upgradient source. However, continuedinvestigations of these data are ongoing as recommended to better assess groundwater flow and waterquality in the area around 37-I. Based on the data collected to date, an interim report on the overall findingswill be submitted to the MOE under separate cover upon completion of the Annual Report.It should be noted that during the assessment of the bedrock groundwater quality all leachate indicatorparameters are used to determine if there are potential landfill impacts occurring. The evaluations of bothchloride and boron as critical leachate indicator parameters is completed as chloride is very mobile andfound at high levels in the landfill leachate and boron, while less mobile than chloride, is only found in thelandfill leachate. Due to the fact that chloride can also come from other sources, if it is found to beincreasing it would only act as an early warning that a change is occurring that may be related to the landfillor some other source. However, should boron begin to increase on its own or with chloride, it is a morecertain indication that landfill impacts are occurring. Therefore, based on the above assessment of thecritical leachate parameters boron and chloride, along with a full analysis of all leachate indicatorparameters, there is no indication of leachate impacts in the bedrock groundwater.In conclusion, the bedrock groundwater quality is found to be similar to previous years.No leachate contamination is observed in the bedrock groundwater, nor would it be expected based on thevery slow rate of groundwater flow downwards through the overlying tills.Since leachate has not been detected in the bedrock, there can be no exceedance of Reasonable Use.However, to further confirm this, groundwater quality at the bedrock locations downgradient of the site havebeen compared to the B7 Guideline Limits (Table C8, Appendix C). As expected, there were no parametersthat exceeded the B7 limit in the bedrock from the landfill. The only exception is at monitor 17-I, where ironappears to exceed the B7 limit. This is considered to be natural and not landfill related for two reasons:a) the upgradient monitors, closer to the landfill, had lower iron concentrations; andb) the actual concentrations observed at monitor 17-I are within the range observed in thebackground monitors.(111414_2ra_apr29-09_city_of_guelph.doc) - 29 -