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i.r Ir Well Destruction Work Plan Advanced Environmental Concepts, Inc. y 1.0 INTRODUCTION This work plan proposes the methods to be used in the destruction of three monitoring wells at the Durham '"' Ferry Ranch (formerly Robert Bogetti &sons property). The property is located at 700 West Linne Road, San Joaquin County, California (Figure 1). V 2.0 BACKGROUND 0.+ As a precursor to foreclosure,AEC performed a Preliminary Site Assessment (PSA) of the subject property on behalf of Prudential Agricultural Investments during August and September, 1996. Two former underground storage tank (UST) emplacements previously containing a total of 3 UST's were identified in the compound w area south of the residential dwelling in the central parcel of the property during the course of the 1996 PSA. The central parcel consists of approximately 1.25 acres of land occupied by single-family residential dwelling, garage,office,domestic well pumphouse,old almond huller,and several outbuildings and storage sheds. This parcel is segregated from the remainder of the property and identified as the Paulson Life Estate. The majority �+ of the property is developed as irrigated agricultural fields and orchard and contained within parcels formerly identified as the Bogetti & Sons property. The 3 UST's, identified as 2-500 gallon gasoline tanks and 1-500 gallon diesel tank, had been excavated and removed from the Paulson Life Estate parcel during July, 1992, No UST removal permitting, regulatory oversight, or soil sampling was performed during the 1992 excavation and removal procedures. As the second phase of this Prudential project,AEC advanced exploratory soil borings and collected soil and �.. groundwater samples in order to assess the presence or absence of petroleum-based contamination in the former UST emplacements during January 1997. These borings also served to quantify concentrations of contaminants present. The January 1997 laboratory results confirmed the presence of soil and groundwater contamination beneath the site but were not judged adequate to delineate the horizontal extent of the soil or groundwater plume. In order to further evaluate the lateral migration of gasoline in the soil and shallow groundwater, AEC performed 60 additional assessment borings at the site on March 11, 1997. The lateral extent of the gasoline plume was defined to the north,east,and south by hand augering 10 additional borings identified as B12H through B21 H. Based on the results of the January and March 1997 exploratory assessment programs, AEC identified 6" significant soil and groundwater contamination beneath the property, primarily associated with the gasoline storage tank emplacement formerly located east of the main storage outbuildings and south of the residential dwelling. San Joaquin County Public Health Services requested voluntary mitigation of the petroleum-impacted 6.+ soil and groundwater beneath the property and agreed to provide regulatory oversight over the project rather than transfer jurisdiction to the California Regional Water Quality Control Board. In October, 1997 AEC began soil excavation activities for the purpose of remediating the site. Soil in the vicinity of the former underground tank emplacement was excavated from surface grade to total depths ranging from 13 to 20 feet below grade in two phases beginning in October 1997 and ending in July 1998. This remedial excavation project was performed in two phases due to delays caused by a legal dispute +..• between the onsite residential tenants of the Paulson Life Estate and Prudential combined with adverse site conditions caused by the unusually heavy seasonal precipitation which occurred during 1997 - 1998. Total vertical excavation depths varied based on daily field observations, interpretation of the analytical results of samples collected during both exploratory boring phases, continuous PID screening of excavated material, and laboratory results of confirmation samples collected during the excavation phases. The horizontal extent of the Project: AEC 98V-1950 1 •ENVIRONMENTAL CONCEPTS WITH DESIGN IN MIND 4400 ASHE ROAD.*206 • BAKERSFIELD.CA 93313 8051831.1646 FAX 8051831-1771 arr