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' Global Presence <br /> Personal Attention <br /> HERST & ASSOCIATES, INC <br /> �r J <br /> 1;a L` j11'J l <br /> ' Mr.Rick Jaime � !; <br /> California Department of Corrections and Rehabilitation <br /> 7650 S.Newcastle Road/P.O.Box 213004 01—'T I 1 20017 <br /> ' Stockton,CA 95213-9004 <br /> f�j ryry L <br /> October 8,2007 J <br /> tDear Mr.Jaime: <br /> Summary of Northern California Youth Center Sampling Results <br /> tSeptember 2007 <br /> On September 11, 2007, sampling was performed at the Northern California Youth Center(NCYC)to <br /> ' provide supplemental information regarding volatile organic compound(VOC) concentrations at Well <br /> #2, Well #4, and the indoor faucet location included in other recent sampling events. Sampling was <br /> performed by Herst&Associates,Inc. VOC analyses were performed by BC Laboratories,Inc. <br /> ' Based on the sample results, there were no MCL exceedances at the indoor faucet location during <br /> September 2007. A summary of detected VOCs is provided in the attached table. <br /> Well #2 (reported to be a supplemental water supply well that operates about 20% of the year during <br /> peak demand periods) continued to exhibit a tetrachloroethene concentration slightly above the MCL. <br /> The September 2007 tetrachloroethene concentration at Well #2 was reported at 6.8 ug/l compared to <br /> ' an MCL of 5 ug/l. <br /> Well #4 (reported to be the primary water supply well for the facility) yielded a tetrachloroethene <br /> ' concentration well below the MCL. The September 2007 tetrachloroethene concentration at Well #4 <br /> was reported at 1.4 ug/1. <br /> ' Quality assurance samples collected during the September 2007 sampling event included a field blank <br /> at Well #2, a field blank at the indoor faucet, a trip blank, and duplicate samples at Well #4 and the <br /> indoor faucet. The field blank sample at Well #2 was collected to provide an indication of VOCs <br /> ' present in the ambient outdoor air or the laboratory analytical process. The field blank sample at the <br /> indoor faucet location was collected to provide an indication of VOCs present in the ambient indoor air <br /> or the laboratory analytical process. The trip blank sample was collected to provide an indication of <br /> ' any 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 September 2007 field blank samples yielded no detectable concentrations of VOCs except for <br /> ' chloroform in the field blank sample collected at the indoor faucet. Water at the indoor faucet has been <br /> chlorinated. Chloroform is a common by-product of the chlorinated water. Chloroform was not <br /> detected in the samples collected from Well#2,Well#4,or the indoor faucet. All VOCs were reported <br /> ' as non-detect in the trip blank sample. Duplicate sample results for the September sampling event were <br /> similar to the original sample results,indicating good reproducibility. <br /> ' 4630 South Highway 94—North Outer Road Telephone(636)939-9111 <br /> St.Charles,Missouri 63304 Fax(636)939-9757 <br /> 1 <br />