AECOM Report B&W - N - City of Guelph

City of Guelph2008 Annual ReportClosed Eastview Road Landfill Site3.6 Effectiveness of the Leachate Collection SystemIn the following discussion, the overall effectiveness of the leachate collection and containment system willbe evaluated based on:a) assessing the overall leachate quantity collected through the use of the detailed water budgetfor 2008;b) confirming that leachate flows freely towards the collection system through the outwash belowthe waste; andc) confirming that the sheet pile wall is still effectively preventing off-site leachate migration asindicated by water level differences.3.6.1 Correlation of Predicted and Actual Leachate Quantities CollectedTo provide a benchmark to assess the effectiveness of the PLCCS in the collection of leachate during 2008, adetailed water budget was once again calculated (Table 4). This water budget is used to predict theapproximate amount of available surplus precipitation that could ultimately infiltrate through the landfill coverand waste and then be collected by the PLCCS. It should be noted that the calculations are for infiltration onlyand do not take into consideration surface water runoff from the landfill, a portion of which could also becollected by the PLCCS.Table 4. Water Balance Calculation for the Closed Eastview Road Landfill – 2008MonthMean Temperature Total Precipitation Evapotranspiration Surplus(°C)(mm)(mm)(mm)January -5.34 95.2 0 92.2February -7.61 104.4 0 104.4March -4.53 80.7 0 80.7April 7.91 63.8 42.5 21.3May 10.18 86 62.8 23.2June 18.83 107 113 -6July 20.29 196.9 133.9 63August 18.40 106.4 111.4 -5September 16.06 121 83.4 37.6October 7.52 53.8 33.7 20.1November 1.31 90.6 4.4 86.1December -5.39 146.6 0 146.6Total Year 1,252 585.2 667.2Average Year* 881 566 316WaterNotes: Soil Moisture Storage Based on 100 mm. / Under Average Conditions for 2008.* 20 year average (1984-2003) for Guelph DamThe detailed water budget determined that overall, 2008 was wetter than an average year (Appendix G).The calculated total yearly surplus precipitation was 667.2 mm (Table 4), which is over double the normal.During and average year, surplus water is available to infiltrate during the winter, spring and fall and there is(111414_2ra_apr29-09_city_of_guelph.doc) - 11 -