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' Global Presence <br /> gt�Qn <br /> HERST & ASSOCIATES, INC.' �� � �� !�✓/L� <br /> M.4 y � 'j Z008 <br /> Ef VIp,0p,ij,,1Epy-,- ,. <br /> ' Mr.Rick Jaime HEALTH <br /> California Department of Corrections and Rehabilitation �'tRr���`TISERVICES <br /> 7650 S.Newcastle Road/P.O.Box 213004 <br /> ' Stockton,CA 95213-9004 <br /> May 21,2008 <br /> ' Dear Mr.Jaime: <br /> Summary of Northern California Youth Center Sampling Results <br /> ' April 2008 <br /> On April 16, 2008, sampling was performed at the Northern California Youth Center (NCYC) to <br /> ' provide supplemental information regarding volatile organic compound(VOC)concentrations at Well <br /> #1, Well #2, Well #4, and the indoor faucet location included in other recent sampling events. <br /> Sampling was performed by Herst & Associates, Inc. VOC analyses were performed by BC <br /> ' Laboratories,Inc. <br /> Well #4 (reported to be the primary water supply well for the facility) yielded a tetrachloroethene <br /> ' concentration well below the MCL. The April 2008 tetrachloroethene concentration at Well #4 was <br /> reported at 1.5 ug/l. <br /> Well #1 (now reported to be a supplemental water supply well that operates about 20% of the year <br /> ' during peak demand periods) exhibited a tetrachloroethene concentration below the MCL. The April <br /> 2008 tetrachloroethene concentration at Well #1 was reported at 3.9 ug/l compared to an MCL of 5 <br /> ug/1. <br /> Well#2(now reported to be utilized only during short term emergencies, should they occur)exhibited <br /> a tetrachloroethene concentration slightly above the MCL. The April 2008 tetrachloroethene <br /> ' concentration at Well#2 was reported at 5.4 ug/l compared to an MCL of 5 ug/1. <br /> The indoor faucet sample yielded a tetrachloroethene concentration of 1.4 ug/l. <br /> Quality assurance samples collected during the April 2008 sampling event included a field blank at <br /> Well#4,a field blank at the indoor faucet,a trip blank,and duplicate samples at Well#2 and the indoor <br /> ' faucet. The field blank sample at Well #4 was collected to provide an indication of VOCs present in <br /> the ambient outdoor air or the laboratory analytical process. The field blank sample at the indoor faucet <br /> location was collected to provide an indication of VOCs present in the ambient indoor air or the <br /> laboratory analytical process. The trip blank sample was collected to provide an indication of any <br /> VOCs associated with shipment or the laboratory analytical process. The duplicate samples were <br /> collected to provide an indication of sampling and laboratory testing reproducibility. <br /> ' The April 2008 field blank samples yielded no concentrations above the Practical Quantitation Limit <br /> (PQL)for all VOCs. All VOCs were reported as non-detect in the trip blank sample. Duplicate sample <br /> 4630 South Highway 94—North Outer Road Telephone(636)939-9111 <br /> St.Charles,Missouri 63304 Fax(636)939-9757 <br /> 1 <br />