ARCHIVED REPORTS_2014_7 - Laserfiche WebLink

Home Browse Search

3-13 0 3.7.7 Site Groundwater Quality The Forward Unit and the Austin Road Unit are now operated as Forward Landfill. WDR Order No. R5-2003-0049 (now rescinded) combined the operations of the two landfills under a single permit. However, it should be noted that while the Forward Landfill operates as one facility, groundwater monitoring for the Forward Landfill are recorded by units (i.e., Austin Road Unit and Forward Unit). Forward Unit: The groundwater quality conditions beneath the Forward Unit during the 2012 monitoring year are generally similar to those observed in previous monitoring years (GLA, 2013). Forward Inc. continues to minimize gas related impacts to groundwater by minimizing interim fill areas that promote ponding of water and continues to install additional landfill gas extraction wells, as needed. Surface water samples collected from the upgradient (FSW-1) and downgradient (FSW-2) surface water monitoring stations during the fourth quarter 2012 monitoring period are generally consistent with each other and no VOCs were detected. These results suggest that landfill operations are not impacting surface water. Austin Road Unit: The groundwater quality conditions beneath the Austin Road Unit during the 2012 monitoring year are also generally similar to those observed in the previous monitoring year (GLA, 2013). In response to continued detection of VOCs in groundwater downgradient of the Austin Road Unit, the RWQCB issued a Clean Up and Abatement Order (CAO) on December 8, 2008. As part of an ongoing Evaluation Monitoring Program (EMP) investigation, 19 additional groundwater monitoring wells have been installed downgradient of the Austin Road Unit. Surface water samples were collected from surface water stations (ASW -1 and ASW -2) during the 2012 monitoring year. Comparison of the upgradient to downgradient samples indicates generally similar concentrations and that the landfill operations are not impacting surface water quality. Background: In September 2000, the RWQCB requested that an assessment of the source and potential impacts of low-level VOC concentrations in the groundwater adjacent to the landfill. The study was performed by GLA and summarized in the Low -Level VOC Detections in Monitoring Wells letter report (February 2001). The study found that other than acetone and methyl chloride (common laboratory contaminants), VOCs were detected in samples from 8 monitoring wells during 1999 and 2000. VOCs were most commonly detected at trace levels and in samples obtained from wells MW -13, MW -14, and MW -21, in the northeastern corner of the Forward Unit. The most frequently detected VOCs in groundwater include: benzene, cis- 1,2-dichloroethene, tetrachloroethene, toluene, 1,1-dichloroethane, and 1,1,1 -trichloroethane. The concentrations at which these analytes were detected did not exceed state or federal drinking water standards. Forward Landfill SWT Engineering Joint Technical Document - April 2014 z:\projects\allied waste\forward\five year permit rvw 2013\jtd-5 yr pr 2013\text\sec 3—final.doc