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QUARTIRLY GROUNDWATER 16ON"15FING FORT
<br /> 620 West Charter Way Stockton California
<br /> 10 INTRODUCTION
<br />' This report documents the results of quarterly groundwater monitoring conducted by
<br /> Aegis Environmental, Inc (Aegis), on April 30, 1992, at the Shell Oil Company (Shell)
<br /> service station located at 620 West Charter Way in Stockton, California (Figure 1) The
<br /> monitoring included collection of depth-to-groundwater measurements and water samples
<br /> from seven (MW-1, MW-3, MW-5, MW-6, MW-8, MW-9, and MW-10) of the ten wells
<br /> located at the site (Figure 2) Monitoring wells MW-2, MW-4, and MW-7 were not
<br /> sampled due to the presence of floating liquid hydrocarbons This report is based, in
<br /> part, on information obtained by Aegis from Shell, Delta Environmental Consultants, Inc
<br /> r (Delta), of Rancho Cordova, California, and Emcon Associates (Emcon) of Sacramento,
<br /> California, and is subject to modification as newly acquired information may warrant
<br /> 2 0 SITE DESCRIPTION
<br /> rThe Charter Way Shell site is an active service station that retails unleaded gasolines
<br /> The site is located in a commercial area of Stockton Details of the site's current facilities
<br />' were reported to Shell by Delta in an "Interim Remedial Acton Plan and Proposed Project
<br /> Schedule," dated April 13, 1990, and a "Quarterly Ground Water Monitoring Report," dated
<br /> March 6, 1992
<br /> 30 BACKGROUND
<br /> On February 8 and 9, 1989, Delta supervised the drilling and sampling of eight soil
<br /> borings at the site The results of the investigation were reported to Shell in a "Pre Tank
<br /> Removal Soil Assessment" report, dated July 17, 1989 The borings ranged in depth from
<br /> 16 5 to 31 5 feet below surface
<br /> I During the week of November 13, 1989, the four existing underground storage tanks
<br /> (UST) were removed and replaced with three UST Soil samples were collected from the
<br /> former tank, new tank, waste-oil tank, and product line excavations The results of this
<br />' activity were reported to Shell by Delta in a reported dated January 30, 1990
<br /> On December 11 and 12, 1989, Delta supervised the drilling of five soil borings on site to
<br />' 40 feet below surface The borings were completed as monitoring wells MW-1, MW-2,
<br /> MW-3, MW-4, and MW-6 On January 10, 1990, two more soil borings were drilled to
<br /> 40 feet below surface and completed as monitoring wells MW-5 and MW-7 On
<br />' January 26, 1990, approximately 10 gallons of floating liquid hydrocarbons were removed
<br /> from MW-2 Liquid hydrocarbon removal has continued at the site Results of these
<br />' activities were reported to Shell by Delta in a "Soil and Groundwater Investigation" report,
<br /> • dated March 6, 1990
<br />' 91 246A QMR 7
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