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± Y 3 <br /> f <br /> 7-7 <br /> � 4 ' GROUNDWX1 ER <br /> - <br /> �. <br /> TECHNOLOGY, INC. <br /> :yU.ill'nllClll[aQnIIt�+htrat',Cun[nYd.Gl4y;i�iFf�lirlia";ti: <br /> i <br /> Februay 22, 1991 <br /> 3 <br /> Job No.203 175 3289.01 <br /> Mr.Clint Rodger <br /> '• Chevron tJ.SA Inc. ITCE/ <br /> 2410 Camino Ramon VQ <br /> San Ramon,CA 94583.0804 r1AR <br /> s <br /> Subject: Groundwater Monitoring and Sampling EIVVjR()NMEN 1 1991 <br /> k <br /> Chevron <br /> South Service <br /> Dorado Street os42 AERM;r"SE�VjCES LTk <br /> Stockton,California <br /> } <br /> This Monitoring and Sampling Letter Report summarizes the results of the groundwater monitoring and <br /> sampling conducr,3d by Groundwater Technology,Irk.at Chevron Service Station No.9-0342, located <br /> at 1374 South EI Dorado Street In Stogy i,California(Figure 1 attached). This report documents the <br /> first in a series of quarterly monitoring and sampling events performed under work release order number <br /> 430-4620,Issued by Mr.Clint Rodgers of Chevron J.S.A. Inc.(Chevron). The site layout and locations <br /> of the three monitoring wells are shown on the attached Site Plan(Figure 2). <br /> s' The three monitoring wells were monitored on January 9, 1991,to determine depth-to-groundwater, <br /> hydraulic gradient and groundwater-flow directlon,and to check for the presence of separate-phase <br /> hydrocarbons. <br /> r Standard operating Procedure(SOP)6, (Appendix A),describes the groundwater-monitoring <br /> procedures. Monitoring was performed using a water-level Indicator graduated to 1/100th of a foot,and <br /> e tha depth-to-water(DTV)measurements were taken from the top of the well casings. These monitoring <br /> data are shown on the standard monitoring data form(attached). <br /> f <br /> The DTW data collocted during well monitoring were combined with wellhead survey Information to <br /> produce the Groundwater Contour Map presented as Figure 3. Compared with the August 1990 water- <br /> level data,the groundwater level has dropped 3 feet. The groundwater gradient measured for the <br /> f January 9, 1991,event Is approximately 0.002 foot-per-foot Jt/tt),in,a northeasterly direction;this <br /> compares with a 0.02 tt/ft gradient to the northwest,which was mwasured In August 1990. Changes of <br /> water level,direction of groundwater flow,and groundwater gradient are not unusual for the <br /> Stockton area,due to the presence of active wells and variable recharge areas. Groundwater behavior <br /> will be monitored In subsequent quarters and compared for signs of seasonal trends. Table 1 <br /> summarizes the August 1990.and the January 1991 groundwater-elevation data(attad*M. <br /> Sepafate-phase hydrocarbons were not detected In any wells monitored In August 19W or <br /> January 1991. <br /> r <br /> f <br /> Offices thr quhrrul the C.K.Canada and Oreneas <br /> y <br />