ARCHIVED REPORTS_2014 - Laserfiche WebLink

Home Browse Search

l MW-2 No general water quality parameter concentration limits were exceeded this period. Two VOCs, PCE and Toluene, were detected at trace concentrations. CFC-12 and 1,2-Dichloropropane were not detected in MW-2 during this sampling period. These two compounds were historically detected at MW-2 until last detected in 2007. The lack of these compounds indicates that landfill gas extraction apparently has been successful in reducing or removing the VOC impact near this well. The trend analysis by Sanitas software indicates increasing trends for Turbidity, TDS, Sulfate, Calcium, Hardness as CaCO3, and Oxygen Reduction Potential and a decreasing trend for Chloride, and PCE during this period. The Electrical Conductivity concentration in this well (376.4 mg/L) is far below the secondary maximum contaminant level (MCL) of 900 uS/cm, which indicates good water quality. TDS has also not exceeded the secondary MCL standards. It is unlikely that the increasing trend in turbidity is a result of landfill activities. Siltation within the well is often the cause of an increase in turbidity that does not affect the water quality of the aquifer outside of the well. As such, turbidity is an indicator of well function and not an indicator of landfill impact to groundwater. MW-3A (Directly Down-Gradient) Concentrations of all the parameters analyzed were within established concentration limits where limits could be determined (Table 1). One VOC (CFC-12) was detected at a trace concentration. MW-4A Concentrations of all the parameters analyzed were within established concentration limits where limits could be determined (Table 1). Two VOCs (PCE and Trans-1,2-Dichloroethene) were detected. The concentration of trans-1,2- Dichloroethene decreased from 21 to 3.7 ppb since the last sampling event. Similarly, PCE decreased from, 0.72 ppb to trace in the same time. This may indicate that these compounds were inadvertently introduced during construction, and are now being purged from the well. MW-5 Concentrations of all the parameters analyzed were within established concentration limits where limits could be determined (Table 1). A trace concentration of PCE and CFC-12 below 1.0 ppb were detected. MW-5 was installed between the sewage treatment ponds of the migrant labor camp and Landfill 2 portion of the site. The purpose of this well is to determine if the treatment ponds were contributing constituents to groundwater. MW-5 is upgradient of Landfill 2 and represents background water quality conditions. Harney Lane Sanitary Landfill 5 Department of Public Works/Solid Waste 1s'Semiannual 2014 Groundwater Monitoring Report County of San Joaquin—July 31,2014