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HYD11,,C ODIC ASSESSMENT RESULTS AND <br /> QUARTERLY aFuumDWATER mowrmw REPORT <br /> 4445 Pershing Avenue Stockton California <br />' The monitoring well was developed and purged, prior to sampling, until a <br /> minimum of three well volumes were removed, respectively The <br /> development and purge water was collected and stored in 55-gallon <br /> Department of Transportation (DOT)-approved barrels for disposal <br /> • A survey of the top-of-casing elevation and location of the well was <br /> completed by Tom O Morrow, Inc , of West Sacramento, California, a <br /> licensed surveyor <br />' The field and laboratory data were analyzed and this report of the <br /> investigation and quarterly groundwater monitoring was prepared <br /> 1 <br /> 20 BACKGROUND <br />' 2.1 Site Description <br /> The site is located on the southwest corner of the intersection of Rose Marie Lane and <br /> Pershing Avenue in Stockton The site is located within a commercial/residential area <br /> The facility is an active service station that retails regular-unleaded, super regular- <br /> unleaded, and super-unleaded gasolines <br /> 2 2 Previous Investigation <br /> Shell removed the former underground storage tanks (UST) and associated piping, and <br /> installed a new double-wall fiberglass UST system in June 1990 Regulatory tank closure <br /> sampling was performed by Aegis and reported to Shell in a "Tank Closure Report," dated <br /> June 14, 1990 Laboratory analytical reports indicated total petroleum hydrocarbons <br /> (TPH), as gasoline, ranged from below the detection limit (BDL) to 4,300 parts-per-million <br /> (ppm) in soil samples collected beneath the former UST Concentrations of benzene <br /> ranged from BDL to 10 0 ppm Subsequent to the UST replacement, Aegis installed, <br /> developed, and sampled three groundwater monitoring wells, MW-1, MW-2, and MW-3, <br /> Eand installed two vapor extraction wells, VIEW-1 and VEW-2, in July 1990 The results of <br /> the July 1990 investigation were reported to Shell by Aegis in a "Monitoring Well <br /> Installation Results Report," dated March 5, 1991 Laboratory analysis of groundwater <br /> samples indicated TPH, as gasoline, and benzene, toluene, ethylbenzene, and total <br /> I xylenes (BTEX) were all BDL at the time of the initial monitoring well installation <br /> 89-016A QMR 2 <br /> h <br />