Laserfiche WebLink
7810 Thornton Road,Stockton,California <br /> 6.0 RECOMMENDATIONS <br /> The initial goal of this preliminary investigation at the former service station <br /> was twofold: first,to determine whether a soil only,or a soil and groundwater <br /> remediation should be considered; and second, if only soil remediation is <br /> required,what is the lateral and vertical extent of the soil contamination?Both <br /> of these goals have been accomplished as a result of this investigation. <br /> The chemical analysis of soil samples collected from exploratory borings <br /> placed around and through.the former tank excavation have confirmed that <br /> although soil contamination is still present,it is confined to the former tank site. <br /> Moreover, the contamination has been restricted to the near-surface clayey <br /> soils and extends to a depth of no more than approximately 16 feet below the <br /> ground surface. <br /> Boring SB 1 .confirmed that the near surface water table (saturated zone) <br /> direct] beneath the site is relative] deep,approximately 50 or more,below the <br /> Y Y p pp Y <br /> ground surface.Based upon the thickness of uncontaminated soils between the <br /> base of the former excavation (16 feet) and the deepest boring (46 feet), it is <br /> evident that the shallow groundwater(water table) has been unaffected by the <br /> release of gasoline from the tank. <br /> As a result of this investigation,it is our recommendation that no further work <br /> be required at this site. Lateral and vertical migration of petroleum hydrocar- <br /> bons has been limited by soil permeability and the low concentrations of these <br /> hydrocarbons in the shallow soils.Augeas Corporation therefore,requests that <br /> site closure be approved by San Joaquin.County. <br /> I <br /> Project Number. USDMO192 Page 8 of 9 <br />