ARCHIVED REPORTS XR0003451 - Laserfiche WebLink

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Ms Marla Guensler Exxon Company, U S A August 16, 1995 Page 2 Analytical Result.. Ground water samples collected from each of the eight monitoring wells on July 14, 1995, were submitted to Sequoia Analytical (a California-certified laboratory) for analysis of benzene, toluene, ethylbenzene, total xylenes (BTEX), and total petroleum hydrocarbons (TPH) as gasoline using EPA Methods 602 and 8015 Modified, respectively Analytical test results are summarized in Table 2 The ground water sample collected from monitoring well MW-3 contained benzene at a concentration of 15 micrograms per liter A dissolved benzene concentration map based on analytical results for ground water samples collected on July 14, 1995, is included as Figure 4 Copies of the laboratory analytical reports are presented in Enclosure B Extended Air Sparging Te§t On March 13, 1995, an extended air sparging test was initiated in ground water monitoring well MW-3 and continued until July 17, 1995 The test introduced compressed air into ground water monitoring well MW-3 at 15 pounds per square inch at a flow rate of approximately 5 cubic feet per minute During the test, monitoring wells MW-1, MW-4, MW-5, and MW-6 were utilized as observation wells to measure the effects of air sparging Dissolved oxygen and carbon dioxide were measured in ground water samples collected from air spargmg well MW-3 Oxygen content and the lower explosive limit (LEL) were measured from air samples collected within the well casing above static water These samples were measured using a LEL meter Pressure readings were collected from the observation wells using a magnehelic gauge temporarily attached to the well heads On July 17, 1995, the air spargmg test was completed and the air compressor was removed from the site Data evaluation is in progress and a summary report will be submitted for agency review Future W rk The next quarterly monitoring event for this site is scheduled for October 1995 Remarks/Signatures The interpretations contained in this report represent our professional opinions, and are based in part on information supplied by the client These opinions are based on currently available information and are arrived at in accordance with currently accepted hydrogeologic and engineering practices at this time and location Other than this, no warranty is implied or mtended