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Water Quality Monitoring Report Forward Landfill sample results. Results from the duplicate groundwater sample collected from well AMW-11 are presented along with the primary data in Table 3-2. The duplicate sample analyses yielded good correlation with quantifiable constituents having a RPD of five percent or less. Review of laboratory analysis dates and required holding times indicates that all samples were submitted and analyzed within the required holding times during the second quarter 2014. 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 (including previously inaccessible offsite EMP wells that were gauged for groundwater elevation in June 2014) 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 and offsite EMP wells generally flows to the northeast at a hydraulic gradient of 0.001 to 0.002 ft/ft, to the north at a gradient of 0.002 to 0.003 ft/ft, and to the northeast at a gradient of 0.003 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: Ki cm 0.001 sec— fit V = —= R0.04—)* ]* 2835 = .324 fit/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= Hydraulic gradient: i gz 0.001 to 0.003 at the site during the second quarter 2014. ne= Effective porosity(ne= 0.35); an estimated value. The estimated groundwater flow rate is calculated to be 0.324 to 0.972 feet/day (118 to 355 feet/year). M:\2014.0012\FA-2Q14rev.docx 10 9/5/2014,Rev.1