Laserfiche WebLink
July 29, 1999 <br /> Page 3 <br /> • April 15, 1999—Additional excavation and sampling was completed to remove the <br /> unidentified piping discovered on April 8, 1999. Over-excavation was also <br /> completed in the area of D-1 and the unidentified piping. Over-excavation in the <br /> southern portion of the site was terminated to protect the structural integrity of the <br /> station canopy supports. Extents of excavation and sample locations for this event are <br /> shown on Figure 4. <br /> • June 1 and 2, 1999—Following removal of the former station canopy, canopy <br /> footings and kiosk, additional over-excavation excavation was completed in the area <br /> of D-1, D-3, PBB-1 and PBW-1. An additional 960 tons of soil were removed to a <br /> maximum depth of 31 feet bgs. Over-excavation was terminated when obviously <br /> impacted soil was removed,the structural integrity of the sidewalk was endangered or <br /> groundwater was encountered. Extent of the additional excavations and sample <br /> locations for this event are shown on Figure 5. Groundwater was encountered at 31 <br /> feet and a grab sample was collected. Results of the groundwater sampling are <br /> included in Table 2. <br /> STOCKPILED SOIL CHARACTERIZATION <br /> Soils generated during the excavation activities were stockpiled on site for charac- <br /> terization and disposal. A total of eleven 4-part composite soil samples were collected <br /> from the stockpile. Soil sample designations, collection dates, and the results of <br /> laboratory analyses performed on these samples are summarized in Table 3. <br /> SOIL DISPOSAL <br /> Manley Trucking transported a total of approximately 1,707 tons of stockpiled soil offsite <br /> for disposal at the Forward Landfill in Manteca, California. The disposal confirmation <br /> sheets are included as Attachment D. <br /> FINDINGS <br /> • The maximum extent of obviously impacted soil was removed. Primary and <br /> secondary over-excavation removed approximately 1701 tons of impacted <br /> soil. <br /> • The majority of the secondary sources (impacted soils)were removed during <br /> over-excavation. Only one area of impacted soil remains under the southern- <br /> most dispenser island near Harding Way. <br /> • Groundwater was encountered during additional over-excavation activities at <br /> a depth of approximately 31 feet bgs. One water grab sample was collected <br /> from the excavation. The grab water sample contained elevated TPH-g and <br /> BTEX levels. <br /> • MtBE was below the method detection limit in all soil samples collected <br /> • following over-excavation. <br /> 9110111 A/Report <br />