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I INTRODUCTION <br /> EA Engineering, Science, and Technology (EA) was retained by Exxon Company, U S A <br /> (Exxon) to install a remediation system to treat groundwater and soil below the water table at <br />' former Exxon Retail Site (RS) 7-3942, located at 4444 North Pershing Avenue in Stockton, <br /> California This report documents the construction and start-up of a vacuum vaporizer well <br /> system, known as UVB (Underdruck Verdampfer Brunnen), for groundwater remediation at <br />' former Exxon RS 7-3942 <br /> The installation of the UVB system consisted of overdri111ng existing groundwater recovery well <br /> RW3 to install the dual-screen UVB well for groundwater extraction-injection, and the <br /> installation of adjacent monitoring wells UVB-MW i and UVB-MW2 to monitor system <br /> performance The work was performed according to the Groundwater Remediation System <br />' Technical Plan (EA 1996) <br /> 1.1 SCOPE OF WORK <br />' The installation and start-up of the UVB system consisted of the following work <br /> • On 1 I November 1996, existing monitoring well RW3 was overdrilled, removed, and <br /> replaced by the UVB well <br /> • From 4 to 6 December 1996, the UVB well was developed <br /> • On 5 February 1997, the installation of the UVB equipment and start-up <br /> troubleshooting was completed The system was tested for air leaks and blockages <br /> • On 6 February 1997, the UVB system was started and an off-gas sample was collected <br />' for laboratory analysis <br /> • On 11 February 1997, the UVB system was shut down for the installation of UVB <br /> monitoring wells UVB-MWI and UVB-MW2 adjacent to the UVB well <br />' • On 14 February 1997, the UVB system was restarted, following the installation of <br /> UVB monitoring wells UVB-MW 1 and UVB-MW2 <br /> • On 17 and 20 February 1997, a UVB off-gas sample was collected for laboratory <br /> ' analysis <br /> • On 24 and 25 February 1997, all onsite and offsite wells, except for MW 11 and the <br /> onsite air sparge wells, were surveyed for vertical elevations and northing and easting <br /> positions <br /> • On 25 February 1997, the UVB system was shut down for the development of UVB <br /> Y p <br /> monitoring wells UVB-MW 1 and UVB-MW2 <br /> WP61 71942 R01397 3 l <br />