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Kicm 0.002 sec– ft V = —= [(0.04—)* ]* 2835 = 0.648 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=Average hydraulic gradient:i z 0.002 for the site during the current(second quarter 2006)monitoring period. ne=Effective porosity(ne=0.35);an estimated value. The groundwater flow rate is calculated to be 0.648 feet/day(237 feet/year). 3.1.4 Detection Monitoring Program Field and laboratory results for the DMP wells for the second quarter 2006 are summarized in Table 3-1 and time-series plots are presented in Appendix D. As shown in Table 3-1,nine VOCs were measured in DMP wells with the greatest number of VOCs (four)measured above the PQL in wells AMW-12,AMW-13, and AMW-14. For the DMP wells at the Austin Unit, CLs are used for the water quality protection standards (WQPS). The CLs shown in Table 3-1 were calculated by Herst&Associates using Sanitas , a state-approved statistical software program are presented in Appendix D. Based on a comparison of the data obtained during the second quarter 2006 monitoring period,the following analytes were found to exceed a CL. CONSTITUENT Concentration DMP MONITORING WELL Limit I AMW-2*I AMW-6 AMW-7 AMW-12 AMW-13 AMW-14 MONITORING PARAMETERS m Barium 0.24 0.270 Bicarbonate 506.3 530 hromium hexavalent 0.0047 1 1 0.0057 0.0079 0.007 VOLATILE ORGANIC COMPOUNDS 1,2-Dichlororoane 0.16 0.54 0.52 is-1 2-Dichloroethene 0.19 8.2 Dichlorodifluoromethane 0.20 0.66 0.78 0.62 Mchloroethene 0.15 11 18 11 loroethene 0.18 1.3 5.0 1.3 NOTES: (*)-Background Well. (j)-Trace Value(between MDL and PQL). DMP-Trend Analyses In order to evaluate changes in water quality in DMP wells at the Austin Unit,historical trends in groundwater were evaluated beginning in 1994 when the groundwater treatment facility(GTF)began operation. The observed groundwater quality constituent trends were evaluated using Sen's Slope trend analyses to determine if significant increasing or decreasing trends were evident in the data. Trend analyses,performed by Herst& Associates, are presented in Appendix D and summarized below. Wells and analytes not discussed below either do not show significant trends (rising or falling)or have too few data points to establish meaningful trends. As shown in the following table,increasing trends were noted for three VOCs in DMP well AMW-13,while decreasing VOC trends were noted in well AMW-14. Of the increasing inorganic constituent trends identified D:V.003_021\ForwardAusBn sP06.doc 11 Geologic Associates