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The groundwater elevation data obtained during this quarterly monitoring period (including the offsite EMP wells)were used to generate the groundwater elevation contour map shown on Figure 3-1,which indicates that groundwater beneath the Austin Unit generally flows to the northeast at a hydraulic gradient ranging from 0.001 to 0.002 ft/ft. 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: Kicm 0.001 sec— ft V = —_[(0.04—)* ]*2835 = .324 ft/day ne sec 0.35 cm —day where: V=Groundwater now velocity. K=Hydraulic conductivity of the water-bearing unit(0.04 cm/sec). i=Hydraulic gradient:i=0.001 to 0.002 for the site during the four quarter 2013. ne=Effective porosity(ne=0.35);an estimated value. The estimated groundwater flow rate is calculated to be 0.324 to 0.648 feet/day (118 to 237 feet/year). Detection Monitoring Program Field and laboratory results for the Austin Unit DMP wells for the fourth quarter 2013 are summarized in Table 3-1. Non-Statistical Data Analysis The non-statistical VOC wa,analyses performed on the DMP well data indicates that there were three non-statistical exceedances for VOCs. The non-statistical exceedances were identified at well AMW-6 as a result of the detection of tetrachloroethene (PCE) above the PQL and dichlorodifluoromethane (DCDFM)at an estimated trace concentration; at well AMW-13 as a result of the detection of PCE,DCDFM, and trichloroethane (TCE) at concentrations above the PQL and 1,1-dichloroethane (1,1- DCA)and trichlorofluoromethane (TCFM) at estimated trace concentrations; and at well AMW-14 as a result of the detection of PCE above the PQL. Trend analyses indicate that statistically significant increasing temporal trends were calculated for PCE and TCE in well AMW-13 and for PCE in well AMW-14. Trend analyses are included in Appendix D. These results are similar to previous results and it is recommended that wells AMW- 6, AMW-13, and AMW-14 be re-designated as CAP wells since they have historically contained VOCs. CA2013.MIWA_4Q13.dw 9 Geo-Logic Associates