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Water Quality Monitoring Report Forward Landfill the Forward Unit flows to the southeast at a hydraulic gradient of 0.003 to 0.005 ft/ft; is while groundwater beneath the northwestern portion of the Forward Unit flows to the northeast at a hydraulic gradient of 0.001 ft/ft. 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 0.005 sec— ft V = —_ [(0.04—)* ]*2835 1.62 ft/day ne see 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;--0.005 at the site during the first quarter 2015. ne= Effective porosity (ne= 0.35); an estimated value. The maximum groundwater flow rate is calculated to be 1.62 feet per day (591 feet/year). 2.1.4 Detection Monitoring Program Field and laboratory results for the Forward Unit groundwater monitoring wells for the first quarter 2015 monitoring period are summarized in Table 2-2. Non-Statistical Data Analysis The California Non-Statistical Data Analysis Method (CNSDAM) was performed for VOCs detected less than 10 percent of the time in background samples. Under the CNSDAM, a measurably significant indication of release occurs in a given sample when: two or more VOCs exceed their respective Method Detection Limits (MDLs); or one or more VOCs equals or exceeds its respective practical quantitation limit (PQL). During the first quarter 2015 monitoring period, non-statistical indications of a release were identified at well MW-13 as a result of a quantifiable concentration of diisopropyl ether (DIPS) (0.58 Vg/L), and at well MW-14 as a result of trace-level concentrations of dichlorodifluoromethane (DCDFM) (0.17j µg/L), tetrachloroethene (PCE) (0.16j Itg/L), and trichlorofluoromethane (TCFM) (0.17j pg/L). In a letter dated April 1, 2015, the RWQCB was notified of these exceedances and retesting is scheduled for April 2015. The results of the verification sampling will be reported under separate cover. On behalf of Forward Inc., GLA performed an assessment of the source and potential impacts of low-level VOCs in groundwater adjacent to the Forward Landfill. It was concluded that the sporadic detection of low-level VOCs in groundwater (and lysimeter M:\2015.0014\FA 1Q15.docx 6 4/27/2015,Rev.0