SITE INFORMATION AND CORRESPONDENCE

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Ms. Kristin Shelton Page 2 of 10 Soil Vapor: ' • TPHg, BTEX compounds and methyl tert-butyl ether (MTBE) by EPA Method TO-3. Water Level Monitoring During the first, second, third and fourth quarters of 2015 a Ground Zero technician measured the depth to groundwater in all site wells and monitored for the presence of free product. The depth to groundwater during the 2015 year ranged from 56.01 feet below ground surface (bgs), as measured in well MW 12 in March, to 60.61 feet bgs, as measured in well MW8 in September. 1 The highest average water levels during the year were recorded during the March 2015 monitoring event and conversely, the lowest average water levels were measured during the September 2015 monitoring event. Water levels rose during the first quarter of the year, fell ' during the second and third quarters of the year and rose during the fourth quarter of the year. The depth to water was not monitored in well VEW 1-D during all 2015 monitoring events because the well was actively being utilized for vapor extraction. Well MW7 was dry when ' monitored during the first, second, third and fourth quarters of 2015. No other site monitoring wells were dry during the 2015 groundwater monitoring events. ' Groundwater flow during the 2015 year ranged from southerly and southeasterly to southerly and southwesterly at gradients ranging from approximately 0.006 feet per foot (ft/ft) to 0.02 ft/ft. During all of the years monitoring events a mound of high groundwater elevation was present around well MW8. The groundwater flow direction and gradients measured during the year were generally consistent with historical data. Monitoring well construction details are presented in Table 1 and groundwater elevation data, flow directions and gradients are summarized in Table 2, both of which are provided in Attachment B. Groundwater gradient maps for each quarter are included in Attachment A. ' Free Product Measurement and Recovery The presence of free floating hydrocarbon product was monitored for in all site wells during each quarterly monitoring event. Well MW6R contained measurable free product during the third quarter of 2015 and well MW9R contained measurable free product during the first, second, third and fourth quarters of 2015. Free product was not present in MW8 during the 2015 monitoring I events. Well VEW l-D was not monitored for free product due to the operation of the SVE system. The greatest thickness of free product was measured by Ground Zero on June 4, 2015, in well MW9R at 0.21 feet. 1 On November 20, 2007, the Keck "Spoiler" Hydrocarbon Recovery Skimming System was reinstalled in well MW8. The skimmer was initially installed on August 10, 2006, the details of which were described in the Skimmer Installation letter dated August 11, 2006. The system consisted of a floating hydrophobic skimmer to separate and recover floating product and an internal bladder pump, operated by compressed air, which lifts the product to the surface, where it is ' stored in a double contained 35-gallon drum. The skimmer failed to perform well with the relatively thin product layer and currently remains non-operational. G:\Dale\GROUNDZE\WOOLSEY.ROB\RepoM\QMR\2015 QMRs\ANNUAL REPORTFinal Textjw.doc