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f Methanol was detected in MW-8 at the low value of 62.µg/L. The compound 1,2 DBA was not detected in any of the monitor wells sampled. The fuel oxygenates DIPE, EtBE, TAME, TBA, and ethanol were not detected at or above the laboratory reporting limit in any of the groundwater samples collected and analyzed from the eight monitor wells. Results.of the analyses are summarized in Table 11. The analytical laboratory data sheets can be found in Appendix B. 3.3 Groundwater Flow Direction and Gradient h: JJW prepared a groundwater potentiometric surface map based on the'static groundwater elevations measured on June 23, 2009 in. the seven monitor wells screened across the groundwater table. During this first half of semi-annual groundwater sampling the groundwater level is approximately thirty-one feet below the ground surface. The groundwater elevations for this sampling event were approximately one foot higher than the last quarterly sampling event in December 2008. The shallow groundwater flow direction, in the vicinity of the former USTs, was calculated to flow toward the southeast with an average, relatively flat, groundwater gradient of approximately 0.0014 ft/ft. This is consistent with the data collected from previous quarters. ' Figure 3 illustrates the groundwater potentiometric surface and flow direction. Based on the analytical data from the monitor wells, the TPH-gasoline plume is inferred to be approximately 90 feet in length along its long axis. The plume is not inferred to extend down gradient very far due in part to the relatively flat groundwater gradient. Figure 4 illustrates the inferred limits of groundwater contamination at the top of the groundwater table for the June E r? 2009 sampling event. 4.0 OZONE SPARGE SYSTEM Lr The ozone sparging system was started, and ozone sparging was initiated on December 1, 2004. On 29 March 2009, sparge point SP-6 was taken of-line and SP-4 put on-line to focus on ozone remediation at the 125 foot bgs level near to monitor well MW-11. From the quarterly sampling event on 9 December 2008, to 30 May 2009, the system ran 60 days out of 172 days, for a total run time of 18,280 hours. From 30 May 2009 to the last time the system was checked, on 7 November 2009, the system:has run continuously for 161 days, and has a total run time of 21,384 hours since initial startup. The ozone generating stations on the ozone sparge system panel are currently plumbed to the following sparge points at the listed depths (feet below ground surface): Sparge Point Depth Sparge Point Depth Sparge Point Death SP-1 50 SP-5 50 SIP 50 SP-2 50 SP-6 SP-10 38 f SP-3 50 SP-7 50 SP-11 50 SP-4 125 SP-8 48 SP-12 50 All the sparge points at the 50 foot level are currently being utilized to maximize the + remediation efforts on the most contaminated zone, the shallow groundwater in the vicinity of the former USTs. One sparge point in each UST excavation pit (SP-6 and SP-10), installed at the top of the groundwater table, has been on-line to remediate soil contamination from ozone system initial startup to 29 March 2009, when SP-6 was taken off-line for the benefit of deeper remediation efforts. Sparge point SP710 is currently still on-line. The system is 4 JJW GEOSCIENCES Inc.