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The groundwater elevation data obtained during the second quarter 2012 monitoring period were used to generate the groundwater elevation contour map shown on Figure 2-1, which indicates that groundwater generally flows to the northeast towards the Austin Unit, at an average hydraulic gradient of approximately 0.003 ft/ft, although a southwest gradient of 0.012 was noted along the northeast perimeter of the Forward Unit. To calculate the approximate linear groundwater flow velocity for the site, conservative assumptions were used, including a hydraulic conductivity of 875 gallons per day per square foot(0.04 cm/sec) and an estimated effective porosity of 35 percent(CH2M Hill 2000). An estimated groundwater flow velocity was calculated using Darcy's Law: Ki cm 0.003 sec– ft V = —_ [(0.04—)* ]* 2835 ,& 0.972 ft/day ne sec 0.35 cm – day where: V=Groundwater flow velocity. K=Hydraulic conductivity of the water-bearing unit(0.04 cm/sec). i=Hydraulic gradient: i,&0.003 for the site during the second quarter 2012. ne=Effective porosity(n,=0.35);an estimated value. The groundwater flow rate is calculated to be 0.972 feet/day(355 feet/year). 2.1.4 Detection Monitoring Program Field and laboratory results for the Forward Unit groundwater monitoring wells for the second quarter 2012 monitoring period are summarized in Table 2-2. As shown in Table 2-2, diisopropyl ether(RIPE) was measured above the PQL in the samples collected from wells MW-2A and MW-16. In addition, tetrachloroethene (PCE) and trichloroethene (TCE) were measured at estimated trace concentrations (between the method detection limit [MDL] and the PQL) in the samples collected from well MW-14 during the second quarter 2012 monitoring period. On behalf of Forward Inc., GLA prepared a letter report dated February 14, 2001 (RWQCB Case No. 2209),to assess the source and potential impacts of low-level VOCs in groundwater adjacent to the Forward Landfill. The letter report concluded that the sporadic detection of low-level VOCs in groundwater(and lysimeter samples) at the Forward Unit are most likely due to landfill gas from unlined unit WMU-B. Forward has continued to minimize gas related impacts to groundwater by limiting interim fill areas that promote ponding of water. Furthermore, in accordance with CCR Title 27, Section 20937, Forward continues to install additional landfill gas extraction wells, as needed. New Historical Intrawell Maximum Values As shown in the table below, two new historical intrawell maximum values were measured during the second quarter 2012 monitoring event, both in background well MW-24. C:\2OI2-0025\FA_2QI2.doc 5 Geo-Logic Associates