ARCHIVED REPORTS_XR0006338 - Laserfiche WebLink

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• 1.0 INTRODUCTION Upgradient Environmental Consultants was retained by Mrs Marjorie Conrady in March, 1998 to provide site remediation and groundwater monitoring services at her property located at 1002 Yosemite Street in Stockton, California The property is the former location of a gasoline service station that was demolished about 1980, when the underground fuel storage tanks were removed Upgradient submitted a Corrective Action Plan in April, 1998, which was approved • by Michael Infurna of the Environmental Health Division of San Joaquin County Public Health Services (PHS/EHD) in nud-April, and the corrective action was performed in late April The purpose of this report is to describe the activities that Upgradient performed during the period, and to present the results that have been obtained to this point The investigation is currently managed for Mrs Conrady by Mr James Dyke of Neumiller& Beardslee, Attorneys at Law 2.0 BACKGROUND 2.1 History and Location The property is located on the northeast corner of Acacia and Yosemite streets in a predominantly residential area of west Stockton (Figure 1) The site is now vacant, but was operated as a gasoline service station from 1961 to 1978 The fuel storage tanks and dispenser islands were removed in 1980, and observers noted evidence of an unauthorized release of gasoline Nothing was done to investigate potential contamination at that time Subsurface drilling to investigate the extent of contamination began several years later (1990) and was conducted in a senes of phases by three consulting firms Included in this drilling effort are ten wells Figure 2 is map of the site presented by the Clearwater Group in its October • 1995 report entitled Report on Sde Aswssnlenl AclnWies, Idol Test, and Orrcarlerly Grounchvaler Monitoring, and shows the location of six groundwater monitoring wells, two wells that were drilled for future soil vapor extraction, two wells that were drilled as air sparging wells, and a cone penetrometer boring that was drilled to investigate the possibility of deep (>70 feet) soil contamination Clearwater used this map as a base for additional maps of the groundwater gradient and contaminant plume, as well as for selecting locations for the borings that were planned as part of the present remedial work Unfortunately, not all of the wells are accurately located on flus map Therefore, Upgradient remapped the site during the first quarter of 1998 and prepared a more accurate well location map (Figure 3) In order to gain a fuller appreciation of the density of coverage of the subsurface data, Upgradient also prepared a composite site map showing the location of all of the previous borings (Figure 4) This map includes the location of 15 probes that were installed by Evax Technologies in 1990 to collect soil vapors (A through O) and 6 soil borings that were drilled by Geological Audit Services in 1992 (BI through 136) It is evident that the site has been extensively investigated to determine the source of the gasoline hydrocarbons and their present extent in both the soil and groundwater 0 2