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Water Quality Monitoring Report Forward Landfill 2.1.2 QA/QC Results The quality assurance/quality control (QA/QC) program completed for the fourth quarter 2016 water quality monitoring event included analyses of two trip blanks, one equipment blank, one field blank, laboratory method blanks, and one duplicate sample (MW -21). The field blanks were analyzed for VOCs by EPA Method 8260 and method blanks were analyzed for all of the analytes included in the monitoring program. The results of the QA/QC program indicate that no VOCs were detected in the trip, field, equipment, or method blanks. Sodium was measured at a trace concentration in one method blank analyzed with groundwater samples. However, sodium was measured at a very low concentration that did not affect the interpretation of primary sample results. The results of the duplicate sample collected from well MW -21 yielded good correlation with a relative percent difference (RPD) less than 8 percent. Review of the sampling dates and laboratory analytical certificates indicates that all laboratory analyses were completed within required holding times. Based on the results of the laboratory QA/QC analyses, it is concluded that the laboratory data generated for the fourth quarter 2016 monitoring period are acceptable and the water quality samples collected from the Forward Unit appear to be representative of water quality at the site. 2.1.3 Groundwater Elevations and Contours Prior to purging and sampling, each well was sounded for water depth using a weighted electronic sounder to an accuracy of 0.01 foot, 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 Forward Unit is summarized in Table 2-3. The groundwater elevation data obtained on November 14, 2016, were used to generate the groundwater elevation contour map shown on Figure 2-1 for the fourth quarter 2016 monitoring period, which depicts groundwater beneath the northern half of Forward Unit generally flowing to the northeast at a hydraulic gradient of 0.002 ft/ft, while groundwater beneath the southern half of Forward Unit generally flowing to the south-southeast at a hydraulic gradient of 0.003 ft/ft, potentially controlled by agricultural well pumping on adjacent properties. To calculate the approximate linear groundwater flow velocity for the Forward Unit, 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: Project No. 2016.0007 l Water Quality Monitoring Report 6 January 2017