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f A S S O C I A T E 5 I N C , <br /> Fes] <br /> SUMMARY REPORT <br /> SUPPLIMENTAL SUBSURFACE INVESTIGATION <br /> E at <br /> SMITHS CANAL PUMPING PLANT <br /> 2144 FONTANA AVENUE <br /> STOCKTON,CALIFORNIA <br /> 1.0 INTRODUCTION <br /> i <br /> r. This report summarizes procedures and practices utilized by ATC Associates Inc. to investigate <br /> petroleum-impacted soil and groundwater associated with the former underground storage tank <br /> (UST) located at 2144 Fontana Avenue Stockton California. Previous investigations have <br /> �.- , <br /> shown that free product was present in the subsurface in the vicinity of monitoring well MW-4. <br /> The purpose of this.investigation was to evaluate current subsurface conditions and potential <br /> }= offsite migration of petroleum hydrocarbons. In brief, the investigation consisted of drilling five <br /> soil borings, collecting soil and groundwater samples, submitting the samples for laboratory <br /> analysis, grouting the borings, and preparing this report. <br /> 1_1 Site Location <br /> The site is located at the south end of Fontana Avenue adjacent to Smiths Canal in Stockton, <br /> California, as shown on Figure 1. The location is generally a residential area. The site is currently <br /> occupied by Smiths Canal Pumping Plant. <br /> f: <br /> 1_2 Site Baekground and Previous Work <br /> r An estimated 1,100-gallons of diesel fuel was reportedly leaked from the above referenced 5,000- <br /> gallon fiberglass tank as a result of an inadvertent puncture. The tank was repaired and returned to <br /> active service. <br /> In May 1988, Ensco Environmental performed a limited investigation, advancing a single soil boring <br /> (B-1)beneath the northern (fill) side of the tank to a maximum depth of approximately 17 feet below <br /> grade. A soil sample collected from this boring at 17-17.5 feet below ground surface (bgs) recorded <br /> 130 parts per million (ppm) total petroleum hydrocarbons as diesel (TPHd). Results of soil sample <br /> analyses are summarized in Table 1. As a result of this initial investigation, the San Joaquin County <br /> Public Health Services Environmental Health Division (PHS/EBD) required further assessment of the <br /> extent of contamination at the subject site. <br /> w:162574162574.02Srcports\sup_su6_inv.doc 1 <br />