ARCHIVED REPORTS THIRD QUARTER GROUNDWATER MONITORING REPORT AUGUST 2015

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' Third Quarter 2015(Semi-Annual)Groundwater Monitoring Report Fomter Pilkington North America,Inc. Lathrop,California Page 6 of 8 ' Table 3.Diesel Thickness Measurements and Product Recover Continued FRe Depth to Depth to Diesel Cumulative Operations and Maintenance ' DateDiesel Groundwater Thickness Diesel Removed Notes feet feet feet (gallons) 14.31 14.48 0.17 0.52 Dry 50.76 14.81 15.89 1.08 77.12 Initial drum measurement was 8/21/15 not taken of on-site 55-gal - 14.18 15.58 1.40 128.99 drum. ' RW-5 14.07 RW-6 Dry 4.27 RW-1 14.44 14.48 0.04 0.55 ' RW-2 Dry, 50.76 RW-3 15.01 15.89 0.88 78.01 RW-5 observed to have 9/3/15moisture in mud on the bottom RW-4 14.49 15.59 1.10 129.87 of the well. ' RW-5 Dry RW-6 I I Dry 4.27 Note:RW-I has a damaged screen and free product measurements at this location may not be representative of subsurface conditions. ' DISCUSSION OF SITE CONDITIONS (APRIL THROUGH SEPTEMBER 2015) ' Third quarter 2015 groundwater monitoring was conducted on August 21, 2015. 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. Groundwater levels were near historic lows, ' which occurred during the 2004-2005 dry season.The groundwater gradient has historically varied from slightly southeast to northeast; typically to the northeast. The calculated groundwater gradient on August 21, 2015 was approximately 0.0033 ft/ft to the east-northeast, consistent with historic groundwater gradients. ' Concentrations of TPH-D, TPH-K, and TPH-MO were not detected at or above the laboratory reporting limits in MW-2, MW-3, and the SW-sump. Diesel was detected above the laboratory reporting limit in ' MW-1 and the SE-sump at concentrations of 0.505 and 1.34 mg/L, respectively. Motor oil was also detected above the laboratory reported detection limits in MW-1 at a concentration of 0.502 mg/L. Low concentrations of TPH-D are sporadically detected in the monitoring well and facility sump samples with ' the highest concentrations typically occurring during seasonal low groundwater periods. Low concentrations of TPH-MO have historically been detected in groundwater samples collected from near the facility, primarily from the SW-sump. The TPH-MO may be related to past site use or a historic ' hydraulic oil release in the cullet tunnel which was investigated, cleaned up to the extent practicable, and which received case closure status prior to the diesel-line release. t Nineteen diesel recovery and skimmer operations and maintenance 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, with the thickest accumulations observed in RW-3. Historically,the wells with thickest measured free product have varied between recovery wells RW-2, RW-3, and RW-4. The greatest free product thicknesses are typically observed during seasonal low groundwater periods and since approximately 2006, the thickest accumulation has typically been measured in recovery well RW-3. Monitoring results for the facility sumps and down gradient well MW-2 indicate that the free product ' plume is stable. ' 4 is CONDOR