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t <br /> PUBLIC HEALTH SERVIds <br /> pp'gU1N�C` <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D., M.P.H., Health Officer <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 952 ILE COP <br /> 2091468-3420 <br /> PETER LENZ MAY 2 6 1999 <br /> 6465 PACIFIC AVE <br /> STOCKTON CA 95207 <br /> I <br /> RE, Howard Lenz Property SITE CODE., 2181 <br /> 1648 Shaw Road <br /> Stockton CA 95207 <br /> San Joaquin County Public Health Services, Environmental health Division (PHS/EHD) <br /> has reviewed the"Site Assessment Work Plan — May 1999" that was submitted by <br /> Advanced Geo Environmental, Inc. (AGE) for the above referenced site and has the <br /> following comments. I <br /> The work plan proposes the advancement of four soil borings on site and the conversion <br /> of,ane of the borings to a dual completed soil vapor extraction/groundwater monitoring <br /> well. The purpose of the proposed work is to define the vertical and lateral extent of <br /> petroleum hydrocarbon contamination in soil, and to begin the investigation of possible <br /> contaminant impact to groundwater. <br /> The purpose of the soil vapor extraction (SVE) well is to conduct feasibility testing for <br /> future remediation alternatives. The levels of total petroleum hydrocarbon contamination <br /> in soil that were documented following the October 1986 removal of the underground <br /> tanks were sufficiently high to expect that remediation at this site will be warranted. As <br /> additional wells will be needed to conduct a SVE pilot test, PHS/EHD recommends more <br /> than one monitoring well be installed during this field mobilization. Two additional wells <br /> should be placed, one in the boring proposed to the west of the former tank pit, and one <br /> to the south of the former tank pit (expected down-gradient direction). Having three <br /> wells on site will allow for calculation of groundwater gradient, as well as provide points <br /> for monitoring radius of influence during the SVE pilot test. <br /> Depth to groundwater at this site is unknown. Depth to water at a site located less than <br /> one half-mile north of the subject site was 60 feet below surface grade (bsg) in <br /> September 1998. Depth to water at a nearby site, 1500 Shaw Road; was approximately <br /> 40 feet bsg in June 1998. The work plan proposes that the total depth of the borings, <br /> and the groundwater monitoring well, will be 65 feet bsg. The work plan also notes that <br /> total depths required may be adjusted in the field, should observations and field <br /> screening with an organic vapor monitor indicate the need. Groundwater gradient is <br /> expected to be to the south. <br /> It is known that pumping from area production wells can influence the groundwater <br /> gradient. Please conduct a well survey that documents the location of all domestic, <br /> municipal, agricultural, industrial and other wells within a 2000-foot radius of the subject <br /> site. The construction of these wells, if known, should be included. <br /> A Division of San Joaquin County Health Care Services <br />