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Water Quality Monitoring Report Forward Landfill groundwater mounding in the vicinity of the front entrance gate due to landscape irrigation. To calculate the approximate linear groundwater flow velocity for the Forward Unit, 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 to 0.016 at the site during the first quarter 2014. ne= Effective porosity (ne = 0.35); an estimated value. The maximum groundwater flow rate is calculated to be 0.972 feet per day (355 feet/year) to the north and northeast and 5.2 feet/day (1,892 feet/year) to the southeast. 2.1.4 Detection Monitoring Program Field and laboratory results for the Forward Unit groundwater monitoring wells for the first quarter 2014 monitoring period are summarized in Table 2-2. Non -Statistical Data Analysis The non -statistical VOCwater analysis was performed on the DMP well data during the first quarter 2014. Review of the analytical data indicates that there was a non - statistical indication of release identified at well MW -2A as a result of a quantifiable detection of diisopropyl ether (DIPE). However, trend analysis did not calculate a statistically significant increasing temporal trend for RIPE at well MW -2A. Trend analysis is included in Appendix D. The occurrence of RIPE in well MW -2A is not believed to be related to a release from the facility, but is believed to be related to the groundwater gradient reversal in the northeast corner of the landfill beginning in the Spring of 2011. With the exception of DIPE, only one estimated trace concentration of a VOC (dichlorodifluoromethane [DCDFM] at well MW -10) was measured in the samples collected from the Forward Unit. 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 M:\ 2014.0012\FA_1Q14.docx 6 4/28/2014, Rev. 0