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tGlobal Presence <br /> Personal Attention <br /> HERST & ASSOCIATES, INC <br /> Mr.Rick Jaime <br /> California Department of Corrections and Rehabilitation (� <br /> 7650 S.Newcastle Road/P.O.Box 213004 <br /> ' Stockton,CA 95213-9004 <br /> March 11 2008 �-` ;,' <br /> ' Dear Mr.Jaime: <br /> ' Summary of Northern California Youth Center Sampling Results <br /> February 2008 <br /> ' On February 22, 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 February 2008 tetrachloroethene concentration at Well#4 was <br /> reported at 1.4 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 <br /> February 2008 tetrachloroethene concentration at Well #1 was reported at 4.0 ug/1 compared to an <br /> ' MCL of 5 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 February 2008 tetrachloroethene <br /> concentration at Well#2 was reported at 5.3 ug/l compared to an MCL of 5 ug/1. <br /> Quality assurance samples collected during the February 2008 sampling event included a field blank at <br /> Well#2,a field blank at the indoor faucet,a trip blank,and duplicate samples at Well#4 and the indoor <br /> faucet. The field blank sample at Well #2 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 February 2008 field blank samples yielded no detectable concentrations of VOCs, except for an <br /> ' estimated concentration of methylene chloride,at the indoor faucet field blank,of 0.28 ug/L. All VOCs <br /> were reported as non-detect in the trip blank sample. Duplicate sample results for the February 2008 <br /> sampling event were similar to the original sample results, indicating good reproducibility. Based on <br /> previous site evaluations,the facility's water supply system provides continuous chlorination treatment <br /> 4630 South Highway 94—North Outer Road Telephone(636)939-9111 <br /> ' St.Charles,Missouri 63304 Fax(636)939-9757 <br />