AECOM Report B&W - N - City of Guelph

City of Guelph2008 Annual ReportClosed Eastview Road Landfill Sitewere well above the LEL as expected for probes in wastes. Probes BH51-I, BH56-I, BH59-I, BH61-I, BH62-I,BH66-I and BH67-I had methane concentrations well below LEL. Probe BH55-I had a methane concentrationslightly above LEL in March, and below LEL in September.Monitors BH51-II, BH55-I, BH56-I, BH57-I, BH58-I, BH61-I, BH63-I and BH66-I are screened in the granularoutwash below the waste. In general, there was little to no methane found in these probes in 2008. Theexception is probe BH55-I, which had gas concentrations above LEL for one of the events. Because the BHseries probes are located in the waste disposal area, high gas concentrations may be expected and are notof concern.6.3.2 Monitors Adjacent to the PLCCS (C and D Series Monitors)The “C” and “D” series probes were designed to monitor the performance of the PLCCS but are also suitablefor gas concentration measurement.The “D” series monitors are located between the PLCCS and the waste. “C” series monitors are locatedbeyond the PLCCS and sheet pile wall.West Side of the SiteMethane concentrations measured in west side “C” and “D” monitors are shown in Table E2 in Appendix E.West side PLCCS manhole methane concentrations are tabulated in Table E7 as discussed in Section 3. Allmonitoring events in 2008 from west side “C” and “D” monitors showed methane concentrations below LEL.Methane concentrations in MH 5W and MH 7W, adjacent to the probes and part of the west side PLCCSmeasured 0% methane during monitoring events in 2008.Low methane concentrations in “C” series monitors are expected on the west side of the site because boththe high water table and the sheet pile wall act as barriers to gas migration. It is also likely that the PLCCSintercepts landfill gas that may not be collected by the gas control system and vents it to the atmosphere.South Side of the SiteTable E3 documents methane concentrations in south side “C” and “D” monitors. Table E6 tabulates southside PLCCS manhole methane concentrations.Monitor D3-I, adjacent to MH 6S and inside the sheet pile wall, showed gas concentration below LEL duringthe March and September monitoring events. The nearby MH 6S recorded gas concentrations below LEL inMarch and September and no methane in June and December.Monitors C5-I, C6-II, C7-I and C8-I, located beyond the sheet pile wall between MH 8S and the South PumpStation, consistently showed no methane during 2008. As noted above, low methane concentrations in “C”series monitors are expected since the high water table and the sheet pile wall act as barriers to gasmigration. The PLCCS also tends to intercept migrating gas and vent it to the atmosphere.(111414_2ra_apr29-09_city_of_guelph.doc) - 50 -