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GEOTHASE <br /> ENVIRONMENTAL <br /> 24 April 2008 <br /> GPE Project No.:480.2 <br /> 0 <br /> Ms. Kathy Amaru L u, <br /> Regional Water Quality Control Board > <br /> 11020 Sun Center Drive, Suite 200 <br /> Rancho Cordova, CA 95670 :Z: E2 <br /> CD rT <br /> Re: Valley Water Site <br /> 612 N Buena Vista,Stockton,CA <br /> Dear. Ms. Amaru. <br /> The subject site is the target of separate remedial investigations of releases of a gasoline UST <br /> and of brine pit release, both of which have impacted the groundwater. Four on-site <br /> groundwater monitoring wells (MW1R to MW-4) have been constructed to investigate- the <br /> distribution of gasoline in groundwater. A fifth well (MW-5) was constructed solely for the <br /> purpose of investigating the down-gradient limit of salt. We completed a round of <br /> groundwater monitoring on April 11, 2008, and have included information from a corrected <br /> laboratory report from the last quarter of 2008. The data summarized below reflect the <br /> corrected lab report as well as the new sample results from earlier this month. <br /> Sample I.D. Date Chloride TDS Sam le I.D. Date Chloride TDS <br /> MW-1 & 1R 12/16/05 4,900 8,200 MW-2 12/16/05 260 1,100 <br /> 3/21/06 3,700 7,300 3/21/06 220 890 <br /> 6/16/06 2,800 6,100 6/16/06 190 896 <br /> 9/6/06 3,400 6,800 9/6/06 180 870 <br /> 3/30/07 1.400 5,900 3/30/07 440. 840 <br /> 6/19/07 2,100 4,300 6/19/07 230 870 <br /> 9/13/07 1,500 3,600 9/13/07 1 220 930 <br /> 12/28/07 1.500* 2,900 12/28/07 530 1,000 <br /> 4/11/08 1.200 2.500 4/11/08 450 940 <br /> replicate 4/11/08 1,100 N/A replicate 4/11/08 290 N/A <br /> MW-3 12/16/05 190 960 MW-4 12/16/05 2,300 4.400 <br /> 3/21/06 190 1 1.100 3/21/06 1,600 3.500 <br /> 6/16/06 180 1,000 6/16/06 1.200 3.300 <br /> 9/6/06 150 1,000 9/6/06 1.100 3,200 <br /> 3/30/07 120 1.000 3/30/07 930 2,900 <br /> 6/19/07 150 960 6/19/07 1,200 2.800 <br /> 9/13/07 140 1,000 9/13/07 1,200 3.100 <br /> 12/28/07 320 980 12/28/07 1,300* 3,000 <br /> 4/11/08 210 880 4/11/08 1,400 2.800 <br /> replicate 4/11/08 130 N/A replicate 4/11/08 1,000 N/A <br /> MW-5 9/13/07 130 1,000 139 Background 3/9/07 100 700 <br /> 12/28/07 140 840 <br /> 4/11/08 120 770 <br /> replicate 1 4/11/08 83 N/A <br /> MDL 1 m 10 nig MDL I mg/L 10 mg/L <br /> MDL'=Method Detect Limit Value <br /> mg/L=Milligrams per Liter <br /> (*)=Corrected Lab Data <br /> 2937 Veneman Ave.,#B240 Geo-Phase Environmental Inc. Phone: (209) 569-0293 <br /> Modesto, Ca 95356 Fax: (209) 569-0295 <br /> ATTACHMENT 2 <br />