ARCHIVED REPORTS THIRD QUARTER GROUNDWATER MONITORING REPORT AUGUST 2015

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' Third Quarter 2015(Semi-Annual)Groundwater Monitoring Report Former Pilkington North America,Inc. Lathrop,California Page 2 of 8 ' Summary of Diesel Skimming Operations(April 1 2015 through September 30,2015) ' Nineteen diesel recovery and skimmer operations and maintenance (O/M) events were conducted at the Site during the current six-month reporting period. Free product was observed in recovery wells RW-1, RW-2, RW-3, and RW-4, and approximately 13.28 gallons of product were recovered during the ' monitoring and skimming period (Figures 3A-3F, Attachment A). Product recovery from the Site's recovery wells has produced a cumulative total of approximately 263.46 gallons of recovered diesel (Figure 4,Attachment A). ' THIRD QUARTER 2015 GROUNDWATER MONITORING EVENT Field Observations On August 21, 2015, a Condor representative measured the depth to groundwater and recorded field observations at the three monitoring wells, and collected groundwater samples from the three monitoring wells and two facility sumps. Field observations included the physical appearance of samples (color, clarity, and presence of petroleum product sheen or phase in samples)and collection of water quality field parameters. Field parameters included dissolved oxygen (DO), oxidation reduction potential (ORP), pH, electrical conductivity (EC), total dissolved solids (TDS), and temperature (see Attachment D for field ' forms). Groundwater field inspection samples collected from the monitoring wells were noted as cloudy without odor or sheen. The monitoring wells were purged until at least three well-casing volumes of water were ' removed and sampled with single-use disposable bailers. All wells were purged until the EC, pH, and temperature stabilized. ' Groundwater elevation measurements indicate that the average groundwater elevation in the three Site monitoring wells on August 21, 2015, was 0.43 feet, a decrease of 1.40 feet since previously measured on February 9, 2015. An estimated groundwater gradient of 0.0033 ft/ft to the east-northeast was calculated ' using water level data from monitoring wells MW-1, MW-2, and MW-3 (Figure 2). The groundwater levels measured on August 21, 2015, are included in Table 1, below. Groundwater measurements are provided in the field forms(Attachment D). Table 1. Groundwater Elevation Data(August 21,2015) Monitoring Well I Screened Interval(bgs) TOC Elevation Depth to Water Groundwater Elevation ' MW-1 7— 17 15.12 14.39 0.73 MW_2 6- 16 15.24 15.21 0.03 MW-3 6- 16 14.81 1 14.29 0.52 'Top of Casing(TOC)Elevation:Elevations surveyed on 05/09/05 relative to NA1)83 and NGVD29 datum. ' bgs:below ground surface All measurements are in feet. ' Laboratory Analytical Results The groundwater samples collected from the three monitoring wells and two facility sumps were analyzed for TPH-D, TPH-K, and TPH-MO by EPA Method 8015M. Laboratory analytical results indicate that ' TPH-MO, TPH-K, and TPH-D were not detected in the samples collected from MW-2, MW-3, and the SW-sump on August 21, 2015. TPH-D and TPH-MO were detected in MW-1 at concentrations of 0.505 and 0.502 milligrams per liter (mg/L), respectively. TPH-D was detected in the SE-sump sample at a concentration of 1.34 mg/L. The samples were analyzed by Excelchem Environmental Labs of Rocklin, California. Laboratory analytical results from the August 2015 sampling event are summarized in Table 2, on the following page, and are also provided in Attachment E. Historic groundwater monitoring data is ' provided in Table A,Attachment C. %4, ' n CONDOR is