SITE INFORMATION AND CORRESPONDENCE

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Mr. Arnold Hof • - 2 - • 19 August 2004 > constituents such as TPH-g, benzene, toluene, ethylbenzene and xylene (BTEX) have been steadily declining since 1998. BTEX compounds are near their respective cleanup goals. In regards to destruction of MW-8 and MW-9, you anticipate requesting a NFA for this site in the near future, and that it will be more economical to destroy all the monitoring wells at one time. We concur, provided that you continue to monitor groundwater elevations in MW-8 and MW-9 until such time as they are destroyed. The Monitoring and Reporting Program No. R5-2004-0805 is enclosed and currently in effect. The fall sampling should occur in the third quarter(July-September) and the Annual Report is due 1 November 2004. Criteria for No Further Action In order for the Regional Board to consider a request for No Further Action, you need to show that concentration trends of nitrate and petroleum are declining, that soil source removal has been competed, and that the expectation of declining trends are likely to continue until water quality objectives are met. Concentrations of benzene hexachloride (BHC) alternate between being detected at 0.1 ug/1 and not being detected at a detection limit of 0.05 ug/l. When BHC is not detected for two consecutive annual sampling events, you may request that Board staff evaluate your site for NFA. Once Regional Board staff concur that NFA is appropriate, you will need to destroy all the monitoring wells under the supervision of the San Joaquin County Environmental Health Department. Summary Regional Board staff made three changes to the MRP subsequent to the draft: 1) since monitoring wells MW-8 and MW-9 have not been destroyed,you need to obtain groundwater elevations annually from these wells until they are destroyed; 2) in the Groundwater Monitoring Table, the Method Detection Limit has been replaced with the Practical Quantitation Limit with the requirement that all detected values falling below the Practical Quantitation Limit and above the Method Detection Limit be reported as trace values; and 3) ammonium has been removed from the schedule. Thank you for obtaining the spring monitoring data and we look forward to seeing the fall monitoring data and report which is due 1 November 2004. If you have any questions, you may contact me at (9 6) 46 4680. Our office has moved and our new address and phone number are on our letterhead. 4 G' TERRELL Private Sites Cleanup Unit Enclosure cc: Mr. Michael Infurna, San Joaquin County Environmental Health Department, Stockton Mr. Michael Miller, Karsyn Environmental Ltd., Rocklin Mr. David Smith, HydroGeologic Inc., Sacramento