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r <br /> � APR 0 8 ,S5 <br /> Uncoil ENVIROMENTAL HEALTH <br /> A S S O C I A T E S F�RMIT�SEF7VICES <br /> Consultants in wastes July 25, 1484 <br /> Management and <br /> Enrironm er'I ai Conl.y! Project 438-•22.01 <br /> Gettler-Ryan, Incorporated <br /> 1992 National Avenue <br /> Hayward, California 94545 <br /> Attention: Mr. Jeffrey M. Ryan <br /> Re: Subsurface Geophysical <br /> Investigations <br /> ARCO Station <br /> I-U8 Benjamin Holt Drive <br /> Stockton, California <br /> Gentlemen: <br /> This letter constitutes our report on soil and ground-water investi- <br /> gations at the ARCO service station located at),908 Benjamin Holt Drive <br /> in Stockton, California. The purposes of the investigations were to <br /> (a) determine the extent of ground-dater contamination resulting from <br /> leakage of gasoline from underground storage tanks at the site, and <br /> (b) initiate development of a plan for remedial action that would miti- <br /> gate the potential hazard to the ground-viater. <br /> FIELD INVESTIGATION PROCEDURES . <br /> Twelve exploratory borings were drilled using continuous-flight, hollow- <br /> stem auger drilling equipment and logged by an EMCON geologist. Soil <br /> samples for logging were obtained from auger-return materials and using <br /> a California split-spoon sampler advanced into undisturbed ground beyond <br /> the tip of the auger. Logs of exploratory borings are attached. <br /> All exploratory borings 'were converted to monitoring wells with the <br /> installation of 3-inch PVC. casing. A summary of well construction. <br /> details is presented on the attached exploratory boring logs. <br /> a; <br /> SOIL AND GROUNID-.•LATER CONDITIONS <br /> The twelve exploratory borings drilled at the site varied in depth from <br /> 19.5 to 30 feet. Surficial clay was encountered in all exploratory <br /> borings to depths ranlino from 8 to 24 feet. This clay is underlain by <br /> an interbedded seauence of, silt, fine sand, and sandy clay. Ground water <br /> stabilized at depths ranging from 9.5 to 11,5 feet on June 21, 1994. <br /> HeadJ.3rIQ,5 <br /> W]q;:•..,$•.oel Sam?c se Cat .�,a�_r*: _. _ -__ <br /> Bmr_n offices 9008a Vtnder•n•gt Ct ccf,m c•a r:a­.,aru 2'03= <br /> legs Scnuyii,u na F'J:,Si:'h•, vc•�sr,.•a:,�o �gjgs - <br />