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Water Quality Monitoring Report Forward Landfill 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. Calcium, magnesium, potassium, sodium, cadmium, lead, tin, and thallium were measured at trace concentrations in several method blanks analyzed with groundwater samples. Similar concentrations of tin were measured in leachate and were flagged as a suspected laboratory contaminant. It should also be noted that anomalous acetone concentrations were measured in several of the primary samples. Since acetone is a common laboratory contaminant and has rarely been detected in groundwater at Austin Unit wells, acetone was also flagged as a suspected laboratory contaminant. Results from the duplicate groundwater sample collected from well AMW-21 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. Review of laboratory analysis dates and required holding times indicates that all samples were submitted and analyzed within the required holding times during the fourth quarter 2017. 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 flows in a northeast direction with an average hydraulic gradient of 0.001 ft/ft. To calculate the approximate linear groundwater flow velocity for the Austin Unit, conservative assumptions were used, including a hydraulic conductivity of 255 feet per day(CDM, 1997), and an estimated effective porosity of 35 percent (CH2M Hill, 2000). The maximum groundwater flow rate is calculated to be 0.728 feet per day(266 feet/year). 3.1.4 Detection Monitoring Program Field and laboratory results for the Austin Unit DMP wells for the fourth quarter 2017 are summarized in Table 3-1. Project No.5017.1030 I Water Quality Monitoring Report 10 January 2018