ARCHIVED REPORTS_2010_20 - Laserfiche WebLink

Home Browse Search

4.5 AUSTIN UNIT 4.5.1 Groundwater Measured groundwater elevations during 2010 generally reflect seasonal precipitation patterns. Hydrographs depicting groundwater elevations over the past 13 years are presented in Appendix D. Overall groundwater flow direction during the 2010 monitoring year were generally consistent with past monitoring periods with flow generally directed to the north and northeast with an average gradient of 0.002 ft/ft. Groundwater quality conditions beneath the Austin Unit during the 2010 monitoring year are generally similar to those observed in the previous monitoring year. For DMP wells, CLs were consistently exceeded in wells AMW-13 and AMW-14 and intermittently in well AMW-6. Both wells AMW-13 and AMW-14 consistently contained VOCs at concentrations greater than the PQL, while low-level VOCs were intermittently measured in well AMW-6. In the CAP wells, VOCs were consistently detected in wells AMW-1, AMW-10, AMW-19, and AMW-19BR at concentrations exceeding the PQL. Trend analyses indicate increasing trends were consistently noted for VOCs in wells AMW-1, AMW-10, and AMW-19, and intermittently in well AMW-I 9BR. The increasing trend exhibited for cis-1,2-DCE at wells AMW-I and AMW-10, suggests reductive dechlorination is occurring in the vicinity of these wells. 4.5.2 Surface Water Surface water samples are collected quarterly from surface water stations ASW-1 and ASW-2. However, with the exception of the first quarter monitoring period surface water station ASW-2 has been reported dry during the 2010 monitoring year. During the year, no CLs were exceeded at downgradient surface water station SW-2. Comparison of the upgradient(ASW-1)to downgradient(ASW-2) surface water samples indicates generally similar concentrations and that the landfill operations are not impacting surface water quality. 4.5.3 Leachate Monitoring According to the Operations Manager,no leachate was taken off site during the 2010 monitoring year. The leachate collection system, which collects leachate from the north face of the landfill, has been operational since November 1996. WQPS (concentration limits) are not required for leachate because it is collected and removed for disposal, rather than discharged. According to the Operations Manager, the leachate monitoring and collection system operated effectively during the 2010 monitoring year. Leachate samples were collected on a monthly basis and analyzed in the field for pH, specific conductance, and temperature. In addition to monthly monitoring, the leachate is sampled annually during the fourth quarter monitoring period for the parameters listed in Table 2-1. The annual leachate sample results indicates that there were no new COCl were identified. D:\2010_0013\FA_4Q10.doc 17 Geologic Associates