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Water Quality Monitoring Report <br /> Forward Landfill <br /> the depth-to-water measurement from the top-of-casing reference elevation. The <br /> current groundwater elevation data for the Austin Unit are summarized in Table 3-6. <br /> The groundwater elevation data obtained during this quarterly monitoring period were <br /> used to generate the groundwater elevation contour map shown on Figure 3-1, which <br /> indicates that groundwater flows in a radial pattern from a groundwater high located in <br /> the vicinity of the infiltration pond along the northern perimeter of the Austin Unit. The <br /> hydraulic gradients vary from of 0.001 to 0.004 ft/ft. <br /> To calculate the approximate linear groundwater flow velocity for the site, conservative <br /> assumptions were used, including a hydraulic conductivity of 875 gallons per day per <br /> square foot (0.04 cm/sec) and an estimated effective porosity of 35 percent (CH21Vl Hill <br /> 2000). An estimated groundwater flow velocity was calculated using Darcy's Law: <br /> Ki cm 0.004 sec— ft <br /> V = _[(0.04 )* ]*2835 = 1.296 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= Hydraulic gradient: i=0.001 to 0.004 at the site during the third quarter 2014. <br /> ne= Effective porosity(ne=0.35); an estimated value. <br /> The estimated groundwater flow rate is calculated to be 0.324 to 1.296 feet/day(118 to <br /> 473 feet/year). <br /> 3.1.4 Detection Monitoring Program <br /> Field and laboratory results for the Austin Unit DMP wells for the third quarter 2014 are <br /> summarized in Table 3-1. <br /> Non-Statistical Data Analysis <br /> During the third quarter 2014 monitoring period, the CNSDAM was performed for VOCs <br /> detected in the DMP wells. As shown in Table 3-1, non-statistical indications of a <br /> release were identified at well AMW-6 as a result of a quantifiable concentrations of <br /> dichlorodifluoromethane (DCDFM) (0.69 Vg/L),tetrachloroethene (PCE) (2.2 µg/L), and a <br /> trace-level detection of trichloroethene (TCE) (0.29j µg/L). In a letter dated October 1, <br /> 2014, the RWQCB was notified of these exceedances. Forward had previously <br /> requested that well AMW-6 be reclassified as a CAP well, since similar concentrations <br /> have been historically measured in this well. There were no other VOCs detected in <br /> DMP wells for the Austin Unit. <br /> M:\2014.0012\FA_3Q14.docx 10 <br /> 10/31/2014,Rev.0 <br />