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• <br /> Executive Summary <br /> Cox & Cox (595 E 11"}' Street, Tracy, CA 95736) is a former gas station site where fuel <br /> leaked from underground tanks The tanks were removed and the site has been <br /> investigated to determine the extent of contamination migration The dissolved <br /> groundwater plume is no longer moving (stable) however, Total Petroleum Hydrocarbons <br /> as Gasoline (TPHG) concentrations in the shallow groundwater have been rising and are <br /> attributed to residual soil contamination around two of the monitoring wells (MW) <br /> These wells, MW-3 and MW-9, are northerly of the building still remaining on site and <br /> down gradient (in the mobile home park) from the former tank pit that was located on the <br /> east side of the building The site currently has several constraints upon it including, <br /> mobile home trailers, numerous unplotted domestic water supply lines, unplotted electric <br /> and natural gas subsurface utilities, a large diameter agricultural irrigation water pipeline, <br /> and City of Tracy subsurface utilities("utilities") <br /> Wright Environmental Consultants proposes to implement an interim remedial action <br /> (IRA) to clean up the residual contamination around the two monitoring wells This IRA <br /> will be limited excavations (removal of contaminated soil) to depths of about 9 to 14-feet <br /> around and between MW-3 and MW-9 The contaminated soil would be excavated, <br /> sampled, and removed while clean excavated soils near the surface would be segregated, <br /> stored on site, and eventually used to refill the excavation The presence of the mobile <br /> homes, loose flowing sands in the upper portions of the excavation, and the presence of <br /> numerous utilities are three constraints that could impact this approach The excavations <br /> would be advanced to the nearest safest point considering these constraints. If needed, <br /> the utilities would be temporarily relocated and/or supported with beams across the <br /> excavation area The site will be fenced with 24-hour security during the period when <br /> excavations are open Open excavations would be kept to a minimum, backfilled at the <br /> close of each workday, thereby ninumizing displacement and discomfort to affected <br /> tenants Groundwater is anticipated to flood the bottom few feet of the excavations The <br /> excavations will be allowed to flood and water will be pumped out to remove <br /> contaminated water The subsurface irrigation pipeline that feeds the canal in front of the <br /> Former Heinz Plant is to be turned off on or about October 31, 2003 The feasibility of <br /> removing soil within feet of the pipeline in the summer months when the pipeline is full <br /> is not an option. Excavation work must be done when the pipeline is empty <br /> It is anticipated that the utility relocation, contaminated soil excavations and hauling, and <br /> backfilling and compaction immediately following the excavation work would take place <br /> over a two-week period This time frame could be shortened if contaminated soil is <br /> allowed to be immediately transported and stored prior to disposal at a permitted off site <br /> location (Forward Landfill) <br /> After excavation work is completed the site will remain in its current uses Some <br /> additional cleanup work may be required depending on the effectiveness of the Interim <br /> Remedial Action work descnbed above <br /> 1 I <br /> i <br /> i <br /> I <br />