ARCHIVED REPORTS XR0004157 - Laserfiche WebLink

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PROJECT 02510.01 January 31, 1991 INTRODUCTION At the request of Ultramar Inc. (Ultramar) , a subsurface investigation was conducted at the subject site. This report presents a description of the investigation procedures, the results of the Soil Gas Survey and Performance Test, an interpretation of the results, and conclusions based on these findings. BACKGROUND The subject site is Ultramar Station No. 696, located at 800 East Highway 12 in Lodi , California. Extensive environmental investigative work has been performed at the site. Work has included drilling of soil borings and installation of groundwater monitoring wells in the boreholes. A vapor extraction system has been installed and operated at the site to remediate soils impacted by petroleum hydrocarbons. PURPOSE AND SCOPE The objectives of this investigation were to 1) define the extent of hydrocarbons remaining in the soil and determine the areas of highest concentrations of hydrocarbon vapors and 2) evaluate the feasibility of using vapor extraction for soil remediation at the subject site: These objectives were met through the completion of a Soil Gas Survey and Performance Test. All data collected in this investigation are considered confidential . and will not be .released to a third party without the- written consent of an authorized representative of Ultramar. PROCEDURES Soil Gas Survey The Soil Gas Survey was conducted January 29 and 30, 1991 at the subject site. Twenty-one existing groundwater monitoring wells were used for the investigation (Figure 1) . Soil gases were analyzed for total volatile hydrocarbons (TVH) during the Soil Gas Survey to 1) screen for the presence of hydrocarbon vapor and 2) delineate the extent of TVH impacted soils at the subject site. A vacuum was applied to each well to extract soil gas. One psi sample pressure was maintained during the analysis. Sample flow rate and instrument pressures were checked before each test. The soil gas was - 1 -