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1EDMUND G. BROWN JF. <br /> p GOVERNOR <br /> OPM <br /> �. IFORNI< <br /> MAY 2 1 2013 SECRETARY FORDRIOU E2 <br /> Water Boards tp p f fNVIRONMFNTAI PROTFf'.Inh <br /> ENp�IY�'dfi...'1Jl�;r dTln��l"is;-'�� - <br /> Central Valley Regional Water Quality Controi Board <br /> 13 May 2013 <br /> Mr. Frank Guinta <br /> Guinta Enterprises <br /> 305 North Union Road <br /> Manteca, CA 95336 <br /> RESPONSE LETTER, CLEANUP AND ABATEMENT ORDER NO. R5-2003-0713, <br /> FRANKS ONE STOP, 2072 W. YOSEMITE AVE., MANTECA, SAN JOAQUIN <br /> COUNTY <br /> This letter is written in response to your 29 March 2013 letter (attached), which <br /> questioned the validity of the laboratory data for the 4 December 2012 (1S) and <br /> 7 January 2013 (2Nd) water sampling of domestic well #17926. The data in your table <br /> on the first page of your letter, reproduced from the 2012 Annual and Fourth Quarter <br /> 2012 Groundwater Monitoring Report (Report) that was submitted by state consultant <br /> GHD to you, was also flagged in the Report on pages 7 (table) and 8 (text) as "suspect" <br /> for the 1St sample event. The 2Nd data result was a confirmation of the 1St data result. <br /> Both analyses reported the identical concentration (MTBE, 240 micrograms per Liter or <br /> ug/L). While it is unusual to see two exact same concentrations reported for two <br /> separate #17926 water sampling events spaced a month apart, it is not unlikely or <br /> necessarily anomolous. <br /> The fact that the sample locations (influent and after the first carbon unit) were <br /> accidentally switched (either by the sampler or due to a lab error in recording a location) <br /> in the 1 St event was very obvious to all of us after the 2Nd event. However, standard <br /> practice requires that when MTBE concentrations increase an order of magnitude (here <br /> to a historical high) from the prior quarters, we would require a 2Nd limited confirmation <br /> sampling event for that well, to validate the 1St event results, even if the two sample <br /> locations had not been accidentally switched. At the request of Regional Board staff <br /> and with agreement from GHD staff, the laboratory was questioned about the matching <br /> laboratory results. Subsequently, the laboratory chemists reviewed and validated both <br /> of the sample events data, and they stand by the MTBE, 240 ug/L results. Future water <br /> sampling events will confirm whether these spikes in MTBE concentrations are <br /> increasing or are decreasing. <br /> Which brings up the question, why did the MTBE increase? The answer may have <br /> been more evident had the offsite monitoring wells been installed to complete the <br /> investigation. There is a high probability that there are pockets of MTBE in the aquifer <br /> KARL E. LONGLEY SCD, P.E.. CHAIR I PAMELA C. CREEDON P.E.. BCEE. EXECUTIVE OFFICER <br /> 11020 Sur,Center Drive#200.Rancho Cordova CA 95670 1 www.waterboaros.ca.gov/centralvalley <br />