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V <br /> 7720 LORRAINE AVENUE <br /> SUITE 105 <br /> STOCKTON,CA 95210 26 October 1990 <br /> PHONE:209-957-3405 <br /> MANAGERS DESIGNERSICOMSULTANTS <br /> Ms. Margaret Lagorio � 1 <br /> Public Health Services <br /> San Joaquin County <br /> P.O. Box 2009 <br /> Stockton, CA 95201 OCT 26 7990 <br /> RE: Laura Scudders/Navarra Ranch Property -N\,!;,'7'0N y,H NiAL i€EAUP <br /> 100 West Valpico Road, Tracy, California PERMIT/SE;;VJCLS <br /> Site Code 14231 <br /> Dear Ms. Lagorio: <br /> The purpose of this letter is to clairify the method and <br /> reporting format of the analysis performed by our laboratory in <br /> support of the above mentioned project. <br /> We received the Laura Scudders Project soil sample identified as <br /> "T-2 15-16 . 5 A, B" for analysis by the Extraction Procedure (EP) <br /> Toxicity Test to determine the concentration of leachable lead. <br /> The extract was analyzed using SW-846 method 6010 which utilizes <br /> the inductively coupled argon plasma spectrophotometer. This <br /> method is preferred to method 7421 for analysis of EP Tox <br /> extracts because of chemical interferences with method 7421, <br /> resulting from the acetic acid used in the extraction procedure. <br /> The method detection limit (MDL) for 6010, although higher than <br /> 7421, is well below the regulatory level for lead of 5, 000 ug/L <br /> or 5. 0 mg/L. <br /> Enclosed is an amended copy of the original report which <br /> clarifies the method used for the lead analysis of the extract. <br /> The results for the lead concentration in the leacheate have been <br /> reported as 11500 u" , expressed in units of ug/L. So that there <br /> is no misinterpretation of this data as reported, the <br /> concentration of lead in the extract was nondetectable at the <br /> reporting limit of 500 ug/L or 0. 5 mg/L, one-tenth the regulatory <br /> limit. <br /> If there are any further questions regarding either the <br /> information presented above or the revised data report, please do <br /> not hesitate to contact me directly. <br /> Sincerely, <br /> Roy F. Weston, Inc. <br /> oseph M. Demmler <br /> Project Manager <br /> JMD:ms <br /> Enclosure <br />