ARCHIVED REPORTS FIRST QUARTER GROUNDWATER MONITORING REPORT FEBRUARY 2014

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1 Pilkington North America,Inc. Site Background Page 10 of 13 One diesel recovery and skimmer O/M event was conducted at the Site between April 1 and June 30, ' 2010. Free product was observed in RW-2 and RW-3, and approximately 2.88 gallons of product were removed during the monitoring and skimming period. Product recovery from the Site's recovery wells has produced a cumulative total of approximately 203.35 gallons of recovered diesel. ' Condor sampled the three Site monitoring wells and two facility sumps during the third quarter groundwater monitoring event conducted on August 2 and 3, 2010. The average groundwater elevation measured in the Site monitoring wells on August 2, 2010, was 2.35 feet, a decrease of 0.43 feet since the previous monitoring event on May 11, 2010, and the calculated groundwater gradient was approximately 0.003 ft/ft to the northeast. Laboratory analytical results indicated that none of the constituents of concern were detected in the monitoring wells or the SE-sump. A low concentration of TPH-D was detected in the ' SW-sump. Five diesel recovery and skimmer O/M events were conducted at the Site between July 1 and September ' 30, 2010. Free product was observed in RW-2, RW-3, and RW-4, and approximately 10.41 gallons of product were removed; product recovery operations have produced a cumulative total of approximately 213.74 gallons of recovered diesel. ' In a letter dated September 7, 2010, Mr. Gerald Djuth of the CRWQCB directed submittal of a work plan to investigate the source of the free product in the recovery wells, and specifically to investigate the possibility of another (post-1996) leak; the Soil Investigation Work Plan dated October 27, 2010, was ' subsequently approved by Mr. Djuth in his letter dated December 15,2010. Condor sampled the three Site monitoring wells and two facility sumps during the first quarter ' groundwater monitoring event conducted on February 7 and 9, 2011. The average groundwater elevation measured in the three Site monitoring wells on February 7, 2011, was 3.21 feet, an increase of 0.86 feet since the previous monitoring event on August 2, 2010, and the calculated groundwater gradient was ' approximately 0.003 ft/ft to the northeast. Laboratory analytical results indicated that none of the constituents of concern were detected in the monitoring wells or the SE-sump. A low concentration of TPH-D was detected in the SW-sump. ' Six diesel recovery and skimmer O/M event were conducted at the Site between October 1, 2010 and March 31, 2011. Free product was observed in recovery wells RW-2 and RW-3, and approximately 5.26 ' gallons of product were removed; product recovery operations have produced a cumulative total of approximately 219.00 gallons of recovered diesel. ' Condor conducted a soil investigation on March 18, 2011. Twelve direct push borings were hydraulically advanced to investigate the soil for residual diesel contamination in utility corridors, near the current fuel dispenser, and near the current 1,000-gallon diesel AST and associated aboveground piping to the standby generator. One soil sample was collected from each boring for laboratory analyses based on field ' observations and PID measurements. No groundwater samples were collected for laboratory analyses because most of the borings were located within the known LNAPL plume. ' Soils encountered consisted of sand and silty sand to the depths investigated at 12 feet bgs, with a thin silty clay to clayey silt horizon often present at 3 to 3.5 feet bgs. Groundwater occurred under unconfined conditions and was measured at an average depth of approximately 11 to 12 feet bgs on March 15, 2011. ' Field observations generally indicated that there was a pattern of greater hydrocarbon impacts with proximity to the location of the original release location. t