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Water Quality Monitoring Report Forward Landfill sampling program are included in Appendix F. Field and laboratory analyses are summarized in Tables 3-1 through 3-9 and cumulative tabulated data for all monitoring points and constituents for groundwater, unsaturated zone, leachate, and surface water are presented in Appendix F. 3.1.2 QA/QC Results The QA/QC program completed for the third quarter 2017 water quality monitoring event at the Austin Unit included analyses of one trip blank, one field blank, laboratory method blanks, and one duplicate sample. The field and trip blanks were analyzed for VOCs by EPA Method 8260 and method blanks were analyzed for all required analyses. The results of the QA/QC program indicate that no VOCs were detected in the trip,field, or method blanks, however, low level metals were detected in several method blanks. Review of the primary results indicates that the low level metal results in the method blank did not affect the primary sample results. Results from the duplicate groundwater sample collected from well AMW-32 are presented along with the primary data in Table 3-2. The duplicate sample analyses yielded good correlation with quantifiable constituents having a RPD within 10 percent. Exceptions include strontium which had an RPD of 16 percent. Review of laboratory analysis dates and required holding times indicates that with the exception of TDS in wells AMW-225, AMW-22, and AMW- 28, all samples were submitted and analyzed within the required holding times during the third quarter 2017. However,the TDS values are within the range of values measured at these wells. Based on the results of the laboratory blank and duplicate analyses, it is concluded that acceptable QA/QC procedures were exercised and the water quality samples collected from the Austin Unit appear to be representative of water quality at the site. 3.1.3 Groundwater Elevations and Contours Prior to purging and sampling, each well was sounded for water depth using a weighted electronic sounder, and the static water level was recorded on a well data sheet (Appendix F). The groundwater elevations were calculated for each well by subtracting the depth-to-water measurement from the top-of-casing reference elevation. The current groundwater elevation data for the Austin Unit are summarized in Table 3-6. The groundwater elevation data obtained during this quarterly monitoring period were used to generate the groundwater elevation contour map shown on Figure 3-1, which indicates that groundwater along the northern perimeter of the Austin unit generally flows in a north- northeast direction with an average hydraulic gradient of 0.002 ft/ft. To calculate the approximate linear groundwater flow velocity for the site, conservative assumptions were used, including a hydraulic conductivity of 255 feet per day and an estimated effective porosity of 35 percent (CDM, 1997). An estimated groundwater flow velocity was calculated using Darcy's Law: Project No.5017.1030 I Water Quality Monitoring Report 10 October 2017