AECOM Report B&W - N - City of Guelph

City of Guelph2008 Annual ReportClosed Eastview Road Landfill Sitecheck dams. Therefore, there is no TSS loading into the wetland. TSS concentrations measured at the othersurface water monitoring stations in 2008 were typical for urban/rural watercourses (Appendix C, Table C3).5.4.3 SummaryThe key highlights of the 2008 surface water sampling program include:a) due to insufficient precipitation and flow only three (Spring Freshet, Summer Rain and FallRain) of the four monitoring events were fully sampled;b) no parameters at SW3A exceeded their respective IAL during the 2008 monitoring period;c) the 2008 surface water chemistry results indicate that the landfill had a negligible effect ondownstream water quality. This was also observed in recent years, since the leachate collectorsystem was installed in 1991; andd) repairs made to the buried surface water storm sewer in 1994 continue to be successful inlimiting leachate infiltration into the storm sewer. Boron concentrations, which had beenelevated in surface water prior to the installation of the leachate collection system, were similarat SW1 and SW16 with all values below the PWQO of 0.2 mg/L.e) The buried surface water storm sewer was also inspected in 2008 with minor repairscompleted.5.5 Adequacy of the Monitoring Program and Recommended ChangesThe monitoring frequency should be reduced from eight events per year to four events per year. Monitoringshould capture two wet events (enough precipitation to cause runoff) and two dry events (no precipitation for48 hours prior to sampling). Attempts should be made to collect at least one of the dry events in the summer(July to September).This revised monitoring program is based on long-term results, which shows that the landfill continues tohave a negligible effect on downstream water quality. This trend has been seen each year since theleachate collector system was installed in 1991. Further, this program will provide more flexibility to ensurethat at least four samples are collected throughout the year.However, current stormwater sampling for TSS should continue at SW24 (rock check dams) for the interim.It is our understanding that that clean fill topsoil will be accepted by the City and stored in the formerstockpile area near SW24. This topsoil is to be used as part of the construction of the proposed post-closurepark that is to be completed on the landfill property. Upon completion of the park, monitoring of SW 24 canbe discontinued.(111414_2ra_apr29-09_city_of_guelph.doc) - 48 -