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• �,t- 1 VOW CE DEC 052001 Ntiitt' ENW7�_ CONDOR EARTH TECHNOLOGIES INC. December 3, 2001 188 Frank West Circle Suite I Ms. Rebecca Setliff Stockton, CA 95206 San Joaquin County Public Health Services/Environmental Health Department (209) 234-0518 304 E. Weber, Third Floor FAX (209)234-0538 Stockton, CA 95202 Re: Proposed Monitor Well Locations, California State University Stanislaus Multi-Campus Regional Center,Stockton, CA Dear Ms. Setliff Condor Earth Technologies, Inc. (Condor) conducted cone penetrometer testing (CPT) and groundwater grab-sampling from November 19 through 21, 2001 at the California State University Stanislaus Mult- Campus Regional Center(site) in Stockton, CA. The site location is shown on Figure 1, attached. Based on the results of the current investigation and previous soil and groundwater investigation, Condor recommends the installation of three shallow groundwater monitor wells at the site. Field Observations Four CPT borings were advanced to depths ranging from 82 to 96 feet to investigate the subsurface lithology and to aid in identifying probable water bearing zones. CPT boring logs indicate the subsurface materials are primarily clays and silts with interbeds of sand, silty sand, sandy silt, and sandy clay. Groundwater Sampling During a soil and groundwater investigation conducted in December 2000, groundwater was first encountered in soil borings at depths ranging from 41 to 44 feet. Groundwater rose in the borings to a depth of approximately 35 feet. Based on the results of the previous investigation and the CPT boring logs, groundwater samples were collected during the current investigation from three depth intervals from direct push borings advanced adjacent to the CPT borings. The depth of each sample interval is noted on the attached Table 1. Groundwater samples were collected using a push-type groundwater sampler. The sampler has a sealed, retrievable stainless steel screen. The sampler was pushed in a closed position to the desired sampling interval. The sampler push rod was then retracted exposing the inlet screen. Groundwater flowed hydrostatically from the formation into the inlet screen. A groundwater sample was retrieved from within the screen with a length of clean, 3/8-inch diameter polytygon tubing with a check valve at the bottom. The tubing was pumped up and down by hand to draw groundwater up the tubing. The groundwater sample was discharged directly from the tubing into laboratory supplied sample containers. All groundwater sample containers were sealed, labeled, and placed in a cooler chilled with Blue Ice® and delivered under chain-of-custody procedures to Excelchem Environmental Laboratories,Inc. of Roseville, California. The samples were analyzed using U.S. EPA Methods and California-approved methods. Laboratory Analytical Results The groundwater samples collected from the borings and monitor wells were analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-G) and total extraorrd,ble petroleum hydrocarbons (TEPH) ENVIRONMENTAL GEOLOGICAL 0 ENGINEERING GEOTECHNICAL http://www.condorearth.com