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PUBLIC r. EALTH SERV- CES a� <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION N :{ <br /> Ernest M. Fujimoto, M.D., M.P.H., Acting Health Officer <br /> 304 E.Weber Ave., 3rd Floor • P. O. Box 388 • Stockton, CA 95201-0388 <br /> 209/468-3420 <br /> GEORGE LECHICH ' <br /> P o Box 881 SAILED AUG 0 11995 <br /> STOCKTON CA 95201 <br /> RE: Valley Showcase SITE CODE: 1114 , <br /> 913 West Fremont Street <br /> Stockton, CA <br /> li <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has <br /> reviewed the June 1995 "Workplan for Soil and Groundwater Investigation Valley Showcase" <br /> prepared by William J. Hunter and Associates for the above referenced site. <br /> The workplan appears to address the investigation of the lateral and vertical extent of soil and ; <br /> groundwater contamination at this site and the installation of an additional downgradient well. <br /> Analysis has been proposed for BTEX and TPH-g. PHS/EHD recommends 8010 as an <br /> additional analysis for soil and 601 as an additional analysis for groundwater to determine if this <br /> UST is the source of solvents detected during the December 1994 quarterly monitoring. <br /> PHS/EHD has reviewed the data for this site and has determined that historically groundwater <br /> is encountered at 15 or 20 feet. However, static water level usually rises to 10 feet bgs once <br /> the borehole encounters first water. The bottom of the tank removal excavation was 13 feet and <br /> was dry. The bottom of the overexcavation was 16.5 feet and groundwater was slowly seeping <br /> in at this depth. Monitoring well logs dated February 28, 1994 and March 1, 1994 indicate <br /> groundwater encountered at 20 feet bgs. Depth to water measurements taken March 8, 1994 <br /> indicated water depth at 13 feet. This data indicates that the borings may have to be drilled <br /> deeper than 10 feet to obtain a groundwater and capillary fringe sample. PHS/EHD <br /> recommends soil sampling to occur every 5 feet until a groundwater sample can be obtained. „ a <br /> 5 <br /> In order to obtain data on the lateral extent of the contamination the workplan proposes three <br /> phases of test points. These three phases are essentially proposed actions for step out borings <br /> from the west, north, and east sides of the former UST excavation. PHS/EHD recommends that <br /> you obtain permits for the sidewalk and street borings from the City of Stockton prior to, <br /> mobilization so that step out borings may be determined based upon field parameters or 24 hour " <br /> turnaround laboratory analysis, thereby, preventing additional mobilization costs. The proposed <br /> downgradient monitoring well location should be determined during this phase of the <br /> investigation. <br /> The proposed stepout boring location west of MW-1 has been eliminated based upon results of. <br /> soil analysis obtained during the installation of MW-1. <br /> , 1 <br /> A Division of San Joaquin County Health Care Services <br /> „ I <br />