ARCHIVED REPORTS_2010_20 - Laserfiche WebLink

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f I f1 i E The fourth quarter 2010 and annual leachate monitoring results are generally similar to those observed historically at the Forward Unit. During the monitoring period, 13 dissolved metal constituents were measured with eight above their PQL;three VOCs were measured above their PQL; eight semi-volatile organic compounds(SVOCs)were measured with three above their PQL; and one herbicide was measured above its PQL in the leachate sample collected during the fourth quarter 2010 monitoring period. No pesticides were detected. The results of the annual leachate sample indicate that no new COCl were detected. During the October and November 2010 inspections,methane concentrations exceeded the regulatory limit of five percent in perimeter soil-pare gas probe GP-I 1. In December,BAS Construction completed the tasks outlined in the landfill gas(LPG)remediation plan which has been submitted to the San Joaquin County Environmental Health Department(LEA)and Cal Recycle to reduce landfill gas near GP-11,and as a result,methane concentrations were less than S percent at gas probe GP-11 during the December 2010 LEA inspection. Groundwater quality conditions beneath the Austin Unit during the fourth quarter 2010 monitoring period are generally similar to historical results. CLs were exceeded in detection monitoring program(DMP)wells AMW-13 and AMW-14,however,with the exception of the barium concentration measured in well AMW-14,no CLs were exceeded for constituents that exhibited statistically significant increasing trends. However,the barium concentration measured in the sample collected from well AMW-14 is within the historical range of values observed at this well,and well below the state primary drinking water standard. In the corrective action program(CAP)wells,trend analyses are performed instead of comparison to CLs. During the current monitoring period,statistically significant increasing trends were noted for one or more VOC constituents in CAP wells AA W-1,AMW-10,AMW-19,and AMW-19BR,while one or more decreasing VOC trends were noted in CAP wells AMW-1,AMW-4,AMW-10,and AMW-11. The increasing cis-1,2-DCE trends in wells AMW-1 and AMW-10,suggest that active reductive dechlorination is occurring in the vicinity of these wells. During the fourth quarter 2010 monitoring period,at the Austin Unit the leachate results are generally similar to those observed historically. During the fourth quarter 2010 monitoring period, 12 dissolved metal constituents were detected with seven measured above the PQL;three VOCs were detected above the PQL;and two trace level SVOCs were detected. No pesticides or herbicides were detected in the leachate sample collected during the fourth quarter 2010 monitoring period. Review of the Annual 2010 leachate sample data indicates no new COCs were detected. According to the Forward Landfill Operations Manager,standard observations have been conducted weekly during the reporting quarter. The Forward Landfill Operations Manager also reported that no surface water was discharged from the facility during the reporting period. CA2010-06l34BorwatdLtr_�P0.dac -2-