AECOM Report B&W - N - City of Guelph

City of Guelph2008 Annual ReportClosed Eastview Road Landfill Siteautomobiles on the adjacent roads, metals in culverts, debris near the watercourse, and disturbedwatercourse sediment in the samples.Comparison of zinc concentrations measured at SW1 and SW16 found that, generally, concentrationsmeasured downstream are equal to or lower than those measured upstream (Figure 20).Iron exceeded its PWQO (0.30 mg/L) at every sampling site, at least once, in 2008. Higher concentrations ofiron were found at SW3A (downstream from landfill), SW2 (on-site station) and SW7 (reference site). Thehighest iron concentrations were measured at the reference site SW7 (0.64 – 27 mg/L) and were above thePWQO on all sampling events. High concentrations of iron at the reference site suggest that elevatedconcentrations of iron occur naturally in this area. Possible sources of iron include the surrounding soils,automobiles on the adjacent roads, metals in culverts, and disturbed watercourse sediment in the samples.At all stations, during all sampling events, boron was below its PWQO (0.2 mg/L).In summary, the 2008 data for the Eastview Road Landfill site showed similar trends to those observed inrecent years. None of the parameters exceeded their respective IAL values at SW3A. PWQO exceedancesof zinc and iron were observed, however these parameters are not indicators of leachate. Since theinstallation of the leachate collection system in 1991, impacted groundwater has not been contributing tosurface water flows at the site, resulting in better water quality than prior to the installation of the system.5.4.2 Suspended SedimentsSurface water sediment control is achieved using two crescent-shaped rock check dams lined with filtercloth, constructed upstream of station SW24 on the existing channel. During rain events, the check damspromote ponding of water between them, thus decreasing the flow velocity and allowing suspended sedimentto settle. Although the silt dams have been working adequately, the City replaced them in the fall of 2008.The effectiveness of the check dams in reducing total suspended solids (TSS) is determined by sampling bothupstream and downstream of the check dam. SW24a is located upstream of the dams, SW24m is located inthe ponded area between the dams, and SW24 is located downstream of the dams. The TSS concentrations(mg/L) for the check dam sites in 2008 are shown in Table 13.Table 13. TSS Concentrations (mg/L) in 2008SiteSpring FreshetSummer RainApril 9, 2008September 16, 2008SW24a (above the check dam)