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d I <br /> Mr. Michael <br /> May 222,, 2008 2008 <br /> CONESTOGA-ROVERS - <br /> & ASSOCIATES <br /> During early March 2008, the Mid-2 sample did not contain TBA (or other oxygenates) but the Mid-3 <br /> sample, downstream of Mid-2, was found to contain TBA during the March l l ° sampling event. The <br /> system was turned off on March 13`s, but resampled before shutdown (a permit condition). In the <br /> interim, a carbon change-out was performed. However, TBA was detected in the March 13s` Mid-2, Mid- <br /> 3, and effluent samples creating a discharge permit non-compliance. We have been unable to determine <br /> why TBA was detected in the Mid-3 sample while not being detected in the Mid-2 sample on March <br /> 11th. <br /> Shell designs and operates all remediation systems with the intent of full compliance with permit <br /> conditions and considers permit non-compliance a very serious matter. The City of Stockton has issued a <br /> Notice of Violation (NOV) for this non-compliance event, and as stated, this is the second NOV Shell <br /> has received for the discharge of TBA into the sanitary sewer. Per the current discharge permit, a third <br /> violation of the discharge permit can result in permanent revocation of our discharge permit for this <br /> system <br /> The above considerations prompted an evaluation of upgrading the existing treatment system, as well as <br /> investigating completely different remediation technologies. Due to the restrictive nature of the discharge <br /> permit conditions and the limitations of carbon treatment for treatment of groundwater at this particular <br /> site, our investigation has determined that an upgrade or expansion of the current carbon treatment <br /> system will not ensure permit compliance. Shell can only consider treatment technologies for this site <br /> that will ensure permit compliance. <br /> We are currently evaluating insitu chemical oxidation as an alternative treatment technology for this site, <br /> We plan to leave the GWE system shutdown until we have determined an appropriate remedial <br /> technology, for site clean up. We expect to complete our evaluation in June. <br /> 240783 2 <br /> Worldwide Engineering, Environmental, Construction, and IT Services <br />