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The groundwater elevation data obtained during the first quarter 2013 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 localized southwest gradient of 0.012 to 0.014 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;:z�0.003 for the site during the first quarter 2013. n,=Effective porosity(n,=0.35);an estimated value. The groundwater flow rate is calculated to be 0.972 feet/day(355 feet/year). Detection Monitoring Program ram Field and laboratory results for the Forward Unit groundwater monitoring wells for the first quarter 2013 monitoring period are summarized in Table 2-2. Non-Statistical Data Anal The non-statistical VOC water analyses performed on the DMP well data indicates that there were two non-statistical exceedances for VOCs. The non-statistical exceedances were identified at well MW-2A as a result of the detection of diisopropyl ether(DIPS) above the PQL and at well MW-10 due to the detection of two VOCs (acetone and dichlorodifluoromethane [DCDFM])at estimated trace concentrations. However,trend analyses indicate that there were no statistically significant increasing temporal trends calculated for the VOCs detected in wells MW-2A and MW-10. Trend analyses are included in Appendix D. 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. The particular VOCs detected in samples during the current monitoring period appear to support this conclusion. Forward has continued to minimize gas related impacts to groundwater by limiting interim fill areas that promote ponding of water. Furthermore, CA2013-0021\FA_1Q13Aoc 5 Geo-Logic Associates