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1 <br /> 1 <br /> 05 May 19976 <br /> 4 <br /> '' <br /> 'AGE-NC Project No 95-0139 ' �' <br /> L Page 4 of 9 , <br /> 1 1 <br /> I from beneath the piping in Decernbef 1988' The soil sample collected in the area,of the east <br /> dispenser island had evidenced'diesel contamination at that time However_, during removal of the ' <br /> piping,no odor or discoloration of the soil was observed, so no further soil sampling was required <br /> 2 4 INSTALLATION'OF UNDERGROUND STORAGE TANKS <br /> In January 1995,-excavation for the installation of two new USTs on a different portion of the subject <br /> site was initiated by SEMCO of Modesto, California,Hydrocarbon-impacted soil was encountered ; <br /> Iduring excavation and the PHS-EHD was notified <br /> ' Excavation resumed on 08 February 1995 The excavation was expanded to approximately 52 by " - <br /> I <br /> 38 feet at the surface and narrowed to approximately 36 feet by 22 feet at the total depth` of 13 feet <br /> ' <br /> for the installation of the USTs Additional excavation 'was performed along the south wall to <br /> remove impacted soil On 09 and 10 February 1995, nine samples were collected from the walls and 1 <br /> floor of the excavation(S-1; S-2,N-1,N-2, W-1, W-2, W-3, F-1 and F-2) Petroleum hydrocarbons <br /> were detected at concentrations as high as 210 ppm in samples collected from the west end of the <br /> excavation Hydrocarbons were not detected in samples collected from the middle or southernend <br /> of the excavation Sample locations are illustrated on Figure 4 Analytical results are summarized <br /> 10 on Table 1 <br /> IAll impacted soil from the excavation was transported to Forward Inc , under non-hazardous waste <br /> manifest and stored under a stockpile agreement pending characterization On 15 February 1995, <br /> three samples were collected from stockpile No 1 (SPI-1 to SPI-3) and 20 samples were collected <br /> from stockpile No 2 (SP2-1 to SP2-20), located at Forward Inc ', (Forward I D Nos CMM-4061 <br /> STP#1 and CMM-14061 STP#2) ,Samples from stockpile No 2 were composited 4' 1 for analysis <br /> Low concentrations of hydrocarbons were detected in seven of,the eight samples analyzed y <br /> r Therefore,'the soil stockpiles were subsequently disposed at Forward Inc Two samples were also <br /> analyzed for total lead for disposal purposes Sample locations are illustrated on Figure 5 TAnalytical <br /> I4 results of stockpile samples�are summarized�on Table 2 <br /> IJ j j <br /> Water was removed during the February-1995 excavation procedures and placed in two 10,000= V <br /> I4 gallon temporary storage tanks On '14 February 1995, water samples were collected from the tanks <br /> by GAS On 24 March 1995,,water samples were again collected from`the tanks by GeoAnaIytical <br /> Laboratories Water in Tank No 1 did not contain petroleum hydr'ocarbons�while water in Tank No <br /> 2 contained low concentrations of hydrocarbons The City of Tracy permitted discharge of Tank No " <br /> I directly tot a'sanitary sewer outlet,on-site Water in Tank No 2 was treated by carbon filtration,' <br /> retested and discharged to the sanitary sewer Analytical results of water samples are summarized { <br /> ' on Table 7 The procedures and findings for the installation of the USTs and overexcavation were <br /> described in the Quarterly Report-June 1995 prepared by AGE , <br /> 1 1 <br /> 1 ' + <br /> 1 i { <br /> 1 <br />