ARCHIVED REPORTS_2013 - Laserfiche WebLink

Home Browse Search

is well below risk-based concentrations and has been attributed to landfill gas. Results of trend analysis performed on these constituents indicate no statistically significant increasing trends. The results of water quality analyses completed from the surface water monitoring stations are generally consistent with previous results. With the exception of a trace detection of toluene at upstream surface water monitoring station SW-I, no VOCs were detected during the monitoring period. A comparison of upstream (SW-I and SW-2) to downstream (SW-3) surface water samples indicates generally similar inorganic constituent concentrations between upstream and downstream surface water monitoring locations, suggesting that the landfill is not impacting surface water quality. Quarterly field screening results from soil-pore gas monitoring probes indicate that no methane was measured in soil-pore gas monitoring probes during the monitoring period. As required every five years, samples collected during the current monitoring period from all groundwater and leachate monitoring wells and surface water monitoring stations were analyzed for the COCs listed in RWQCB Order No. R5-2007-0046. With respect to organic COCs,one semi-VOC (dimethyl phthalate) was detected in samples from wells MW-2, MW-6A, and MW-10A. Additionally, 2,4-D was detected in all surface water samples and dimethoate was detected in upstream surface water samples. When detected, concentrations of organic COCl were comparable between upgradient/upstrearn and downgradient/downstream samples. Accordingly, the presence of these insecticides and herbicides are believed to be related to agricultural activities upgradient of the site. Inorganic COCs were generally measured at similar concentrations in both upgradient/upstrearn and downgradient/downstream samples. However, while cyanide was not detected in upstream surface water sample, it was measured above the PQL in the sample from downstream surface water station SW-3. Accordingly, surface water location SW-3 will be sampled and retested for cyanide and the results reported in the July- December 2013 monitoring report. Based on the results of the COC analyses,no changes to the current monitoring program are recommended at this time. I certify under penalty of law, that I have personally examined and am familiar with the information submitted in this document and all attachments,and that based on my inquiry of those individuals immediately responsible for obtaining this information, I believe that the information is true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment. If you have any questions regarding this report, please call me at (209) 982-4298. Sincerely, Jllmlk 11 C�/VV Erin Fanning Environmental Manager Attachment -2-