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Mr. James Mills - 2 - 28 April 2000 <br /> purging/sampling) to lessen the disturbance and alteration of groundwater intended for analysis. <br /> This evaluation should include consideration of well redevelopment, which could increase the <br /> productivity of the monitoring wells. <br /> 4. The report states that MTBE was not detected above the reporting limit of 5.0 µg/1 in any wells. The <br /> acceptable reporting limit for MTBE is 0.5 µg/l, for nondetectable results. Unless historic data are <br /> available showing MTBE analyses using a maximum detection limit of 0.5 µg/1, additional analyses <br /> will be required. All MTBE analytical results and maximum reporting limits for nondetections <br /> (current and historic) shall be included in Table 3 - Historic Groundwater Analytical Data. <br /> 5. SECOR recommends continued weekly free product removal from MW-3 and continued <br /> groundwater monitoring at reduced frequencies in selected wells. Under separate cover, I am <br /> sending you a draft revised Monitoring and Reporting Program (MRP)your review and comment. <br /> Once we have received your comments, the final revised MRP should be available for the second <br /> quarter(April-June 2000) monitoring event. <br /> 6. In Table 4 of the report, there are asterisks in the last column; however, no footnote is present <br /> defining the asterisks. The legend should define the footnotes and abbreviations used in the table. <br /> 7. In future annual reports, graphical representations of the analytical data results shall be provided for <br /> analytes detected in each well. Available historical data(if accessible) shall be included on the <br /> graphical diagrams to provide a summary of contaminant trends in each well. <br /> 8. Due to the continued presence of free-phase product in MW-3, an evaluation of remedial alternatives <br /> is needed (e.g., soil vapor extraction) to remove contaminants from soil and groundwater at the site. <br /> We understand that intrusive activities are constrained due to the condition of the levee; however, <br /> minimally invasive and non-invasive alternatives may expedite the remediation of soil and <br /> groundwater at this site. The evaluation should include determining whether there are on-going leaks <br /> at the site continuing to release petroleum constituents to the environment. <br /> By 26 May 2000, please respond to these comments and submit the evaluations described in items 3 and <br /> 8 above. If you have any questions, you may contact me at (916) 255-3119. <br /> tizzi <br /> J SSICA HARDY <br /> ngineering Geologist <br /> cc: Mr. Mike Infurna, San Joaquin County Public Health Services, Stockton <br /> Ms. Susan Gahry, SECOR International Inc., Oakland <br />