ARCHIVED REPORTS XR0003452 - Laserfiche WebLink

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Ms Marla Guensler Exxon Company, U S A June 8, 1995 Page 2 Table 2 Ground water samples collected from monitoring wells MW-1, MW-2, and MW-4 through MW-8 did not contain detectable concentrations of petroleum hydrocarbons A dissolved benzene isoconcentration map based on analytical results for ground water samples collected on April 5, 1995, is included as Figure 4 Copies of the laboratory analytical reports are presented in Enclosure B Extended Air Sparging Test On March 13, 1995, an extended air spargmg test was initiated in ground water monitoring well MW-3 and is anticipated to operate for four months The test introduces compressed air into ground water monitoring well MW-3 at 15 pounds per square inch (psi) at a flow rate of approximately 5 cubic feet per minute (cfm) During the test, monitoring wells MW-1, MW-4, MW-5, and MW-6 are utilized as observation wells to measure the effects of air sparging. Dissolved oxygen and carbon dioxide are measured in ground water samples collected from air sparging well MW-3 Oxygen content and the lower explosive limit (LEL) are measured from air samples collected within the well casing above static water These samples are measured using a LEL meter Pressure readings are collected from the observation wells using a magnehelic gauge temporarily attached to the well heads Additional ground water samples were collected from monitoring wells MW-1, MW-3, MW-4, MW-5, and MW-6 on March 31, 1995 to assess the effect of the ongoing air sparging test being performed at the site These samples were also submitted to Sequoia for analysis of BTEX and TPH as gasoline Analytical test results are summarized in Table 2, and copies of laboratory analytical reports are presented in Enclosure B The extended air sparging test will continue through July 1995 Upon completion a report will be prepared and submitted for agency review Future Work The next quarterly monitoring event for this site is scheduled for July 1995 In addition, the extended air sparging and soil vapor extraction test will continue until Julie 15, 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 intended