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• generally similar inorganic constituent concentrations. With the exception of an estimated trace-level detection of toluene in upstream station SW-1, no VOCs were detected in the surface water monitoring stations, suggesting that the landfill is not impacting surface water quality. Stream gauging was performed on March 25 and May 21, 2013, at monitoring points SG- S and SG-2 and the data is summarized in Table 5. As shown in Figures 1 and 2, monitoring point SG-1 is located upgradient in the Walker Slough and monitoring point SG-2 is located upgradient in the French Camp Slough. 5.0 SOIL-PORE GAS MONITORING In accordance with WDR Order No. R5-2007-0046, soil-pore gas probes are monitored semiannually using a field screening protocol, and soil-pore gas samples are only collected if field screening indicates methane concentrations greater than 2.5 percent. During the monitoring period, field screening of soil-pore gas probes was conducted on March 26, 2013. As shown on Table 6, methane was not detected in any of the soil-pore gas probes, and as a result, no samples were collected. 6.0 CONSTITUENTS OF CONCERN During the first quarter 2013 monitoring period, groundwater, leachate, and surface water samples from the French Camp Landfill were analyzed for the five-year COCs listed in RWQCB Order No. R5-2007-0046 and are summarized in Tables 2, 3, and 4. As shown in Tables 2 and 3, with the exception of one semi-VOC (dimethyl phthalate)that was detected in samples at both upgradient and downgradient monitoring wells, no organic COCs were detected in the groundwater or leachate monitoring water samples. Generally similar concentrations of diethyl phthalate, which is used in insect repellant, were measured in the upgradient and downgradient samples. Accordingly, it is believed that the source of this constituent is from agricultural activities upgradient of the landfill. For surface water samples (Table 4), 2,4-D (herbicide) was detected in samples from both upstream and downstream surface water samples and dimethoate (insecticide) was detected in upstream surface water samples. Since these constituents were measured at the highest concentrations in upstream surface water samples, their presence is believed to be related to agricultural activities upgradient of the landfill. No other organic COCs were detected in surface water samples. Several inorganic COCl were detected in both upgradient/upstream and downgradient/downstream monitoring wells and surface water stations. The similarity in the concentrations in both upgradient and downgradient wells and surface water stations suggest that the inorganic COCs are naturally occurring. However,cyanide was not detected in the samples from surface water monitoring stations SW-1 and SW-2, though a quantifiable concentration of cyanide was measured in the sample from downstream surface water station SW-3. Cyanide will be retested at surface water station SW-3 and reported in the July-December 2013 monitoring report. • C:\2013-002AFC ISA13.doc 5 Geo-Logic Associates