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March 7, 2019 | Page 3 File No. 0504-119-01 <br />Purge water generated during groundwater sampling was drummed and labeled for future disposal at a <br />permitted facility. <br />4.3. Monitored Natural Attenuation Parameters <br />Water quality parameters, including turbidity, DO, ORP, specific conductivity, pH, and temperature were <br />measured in the field using a calibrated water quality meter equipped with a flow-through cell and the <br />results are summarized in Table 1 below. Relatively low DO and ORP levels at MW-2, within the former UST <br />basin indicate the potential reducing conditions that support bioremediation. The ORP levels in the <br />upgradient well (MW-1) and downgradient wells (MW-5 and MW-6), are elevated; as is ORP in MW-3 which <br />is closer but cross-gradient to the former UST area. DO is high in MW-1 and MW-6, moderately high in MW- <br />3 and low in MW-4 and MW-5, possibly indicating an anaerobic zone extending from MW-2 to MW-5. <br />TABLE 1. DEPTH TO GROUNDWATER AND GROUNDWATER QUALITY PARAMETERS <br />Monitoring <br />Well ID <br />Depth to Water and Field Measured Natural Attenuation Parameters <br />Depth <br />to <br />Water <br />(feet) <br />Groundwater <br />Elevation <br />(feet) <br />pH <br />(pH <br />units) <br />Specific <br />Conductivity <br />(mS/cm) <br />ORP <br />(mV) <br />Dissolved <br />Oxygen <br />(mg/L) <br />Turbidity1 <br />(NTU) <br />Temperature <br />(degrees C) <br />MW-1 3.80 1,573.84 7.08 0.568 166.7 2.75 10.4 7.0 <br />MW-2 3.70 1,573.38 6.66 0.689 130.5 1.22 4.8 5.5 <br />MW-3 3.86 1,573.16 6.94 0.814 168.8 0.80 4.9 8.4 <br />MW-4 4.43 1,572.29 7.14 0.733 140.5 0.97 2.6 12.7 <br />MW-5 4.39 1,569.84 7.08 1.152 170.5 1.39 9.4 8.3 <br />MW-6 4.98 1,571.49 7.29 0.647 164.3 6.26 4.1 9.4 <br />Notes: <br />1Turbidity is not a natural attenuation parameter but was measured in the field to evaluate groundwater stabilization. <br />2 Groundwater elevations calculated using the formula: Groundwater Elevation = Top of Casing Elevation - Depth to Water <br />mS/cm = milliSiemens per centimeter; mV = millivolts; mg/L = milligrams per liter; NTU = nephelometric turbidity units <br />5.0 CHEMICAL ANALYTICAL RESULTS <br />Six groundwater samples, and one duplicate, were submitted to TestAmerica for the chemical analyses <br />described in “Section 3.0 Scope of Services.” This section presents the analytical results for groundwater <br />samples collected during the January 2019 monitoring event. <br />5.1. Groundwater Chemical Analytical Results <br />Six groundwater samples, and one duplicate, were submitted from monitoring wells MW-1 through MW-6 <br />to TestAmerica for the chemical analyses described in “Section 3.0 Scope of Services.” The duplicate <br />sample was collected from monitoring well MW-2. TestAmerica’s laboratory report is included in Appendix B; <br />chemical analytical results are summarized and compared to MTCA Method A cleanup levels for <br />unrestricted land use in Table 2 and summarized below. Contaminants were not detected in the samples <br />collected from MW-1 through MW-6.