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® at a hydraulic gradient ranging from approximately 0.002 ft/ft to 0.013 ft/ft, although a localized southern gradient is noted in the northeast corner 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 0.013 sec– ft V = — _ [(0.04 —)* ]*2835 4.21.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 0.002 to 0.013 for the site during the second quarter 2013. ne=Effective porosity(ne=0.35);an estimated value. The maximum groundwater flow rate is calculated to be 4.21 feet per day(1,537 feet/year). Detection Monitoring Program Field and laboratory results for the Forward Unit groundwater monitoring wells for the ® second quarter 2013 monitoring period are summarized in Table 2-2. Non-Statistical Data Analysis The non-statistical VOC Water analyses performed on the DMP well data indicates that there were non-statistical exceedances for VOCs. One non-statistical exceedance was identified at well MW-2A as a result of the detection of diisopropyl ether(RIPE) and acetone above respective PQLs and chloromethane at a trace concentration. Additionally, a non-statistical exceedance was identified due to the detection of acetone and chloromethane above respective PQLs at well MW-10. Trend analyses indicate that there is a statistically significant increasing temporal trend for DIPE at well MW-2A. However, no statistically significant increasing temporal trends were calculated for acetone and chloromethane at wells MW-2A and W-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, in accordance with CCR Title 27, Section 20937, Forward continues to install additional ® landfill gas extraction wells, as needed. C:U013-0021TA_2Q13.doc 5 Geo-Logic Associates