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17 <br />r1 <br />U <br />Water Quality Monitoring Report <br />Forward Landfill <br />Ki crn 0.003 sec — ft <br />V = — = [( 0.04 —) * ] * 2835 - 0.972 ft / day <br />ne sec 0.35 cm — day <br />where: V= Groundwater flow velocity. <br />K = Hydraulic conductivity of the water -bearing unit (0.04 cm/sec). <br />i = Maximum hydraulic gradient: i gz� 0.003 during the fourth quarter 2016. <br />ne= Effective porosity (ne = 0.35); an estimated value. <br />The maximum groundwater flow rate is calculated to be 0.972 feet per day (355 feet/year). <br />2.1.4 Detection Monitoring Program <br />Field and laboratory results for the Forward Unit groundwater monitoring wells for the fourth <br />quarter 2016 monitoring period are summarized in Table 2-2. <br />Non -Statistical Data Analysis <br />The California Non -Statistical Data Analysis Method (CNSDAM) was performed for VOCs <br />detected less than 10 percent of the time in background samples. Under the CNSDAM, a <br />measurably significant indication of release occurs in a given sample when: two or more VOCs <br />exceed their respective Method Detection Limits (MDLs); or one or more VOCs equals or <br />exceeds its respective practical quantitation limit (PQL). During the fourth quarter 2016 <br />monitoring period, non -statistical indications of a release was identified at well MW -2A as a <br />result of trace concentrations of 1,1-dichloroethene (1,1 -DCA) and cis- l,2-dichloroethene (cis- <br />1,2-DCE); MW -16 as a result of a quantifiable concentration of diisopropyl ether (DIPE); and at <br />well MW -17 as a result of a trace concentration of trichlorofluoromethane (TCFM) and <br />quantifiable concentrations of chloroform and carbon tetrachloride. Similar concentrations of <br />VOCs in wells MW -2A, MW -16, and MW -17 were previously reported to the RWQCB and <br />confirmed in retest samples. It should be noted that these confirmed VOCs remain well below <br />state and/or federal maximum contaminant levels (MCLS), and were place in "tracking mode" <br />and are being evaluated quarterly for temporal trends (discussed below). <br />Historically, low-level concentrations of VOCs have been detected in the samples collected from the <br />Forward Unit. On behalf of Forward Inc., GLA prepared a letter report dated February 14, 2001 <br />(RWQCB Case No. 2209), to assess the source and potential impacts of low-level VOCs in <br />groundwater adjacent to the Forward Landfill. The letter report concluded that the sporadic <br />detection of low-level VOCs in groundwater (and lysimeter samples) at the Forward Unit are most <br />likely due to landfill gas from unlined unit WMU-B. Forward has continued to minimize gas related <br />impacts to groundwater by preventing ponding of water through regular site maintenance. <br />Furthermore, in accordance with CCR Title 27, Section 20937, Forward continues to install <br />additional landfill gas extraction wells, as needed. <br />Project No. 2016.0007 1 Water Quality Monitoring Report 7 <br />January 2017 <br />