AECOM Report B&W - N - City of Guelph

City of Guelph2008 Annual ReportClosed Eastview Road Landfill SiteAs stated earlier, the recommended reduction in groundwater monitoring is to decrease the currentfrequency by half for most locations. This reduction is acceptable as discussed below for each of thegeological units monitored:• Sampling of the leachate and the outwash beneath the waste can be reduced from quarterly tosemi-annual as the water quality has remained similar over the years as discussed in the AnnualReports. This will still include the annual monitoring for Volatile Organic Compounds (VOCs);• Sampling of the sandy outwash monitors on quarterly basis can be reduced to semi-annual, aswell, monitors on a semi-annual basis can be reduced to annual. Water quality at most sandyoutwash monitors have generally remained similar to previous years, most noticeably at thelandfill property boundary and off-site. Although road salt effects continue to be observed atlocations 10, 13 and 14 (near Watson and Eastview Road), a reduction is still warranted as thisis not landfill related as has been known and documented since the mid 1990s. However,monitor 30-I (western wetland), although upgradient of the landfill, should remain at a semiannualfrequency as it has been recently experiencing increasing chloride, which is most likelyrelated to road salt effects;• Sampling of the upper till monitors on quarterly basis can be reduced to semi-annual, as well,monitors on a semi-annual basis can be reduced to annual. Water quality in the upper till hasremained similar over the years and has exhibited very little variation over time at most locations.• Sampling of all the lower till monitors, whether on a quarterly basis or semi-annual basis can bereduced to annual. Water quality in these monitors has remained similar over the years and hasexhibited very little variation over time. Further, the rate of groundwater movement downwardsthrough the till is only a few centimetres per year, as discussed in the annual reports, therefore,should any impacts occur, they would take hundreds of years to migrate to the lower till.However, monitor 4-IIR should remain at a semi-annual frequency for the interim. This monitorwas recently replaced as the original monitor was experiencing a leaky seal based on increasingchloride from shallow road salt impacts.• Sampling of selected bedrock monitors can be reduced from a quarterly or semi-annual basis toa semi-annual or annual basis. Water quality in these monitors has remained similar over theyears and has exhibited very little variation over time. However, monitors 4-IR, 37-I, 50-I, 53-IR,91-I, 93-I, 94-I and 95-I should continue to be sampled on a quarterly basis for the interim, until aresolution of Condition 17.10 has been completed. Further, monitors 37-I/50-I and the recentlycompleted monitors 93-I, 94-I and 95-I should continue at a quarterly basis until resolution of theincreasing chloride issue with respect to location 37/50. This issue is currently underinvestigation. Once a resolution of these issues has been rendered, these locations can bereduced to a semi-annual bases.Water Level MonitoringRoutine water level monitoring should remain at a quarterly frequency, as in the past, so that groundwaterflow conditions can still be assessed throughout the year.Reduction of the monitors as part of the monthly water level monitoring requirement to only reflect thequarterly frequency is warranted, at this time, for locations in the lower till and landfill waste. Water levels in(111414_2ra_apr29-09_city_of_guelph.doc) - 40 -