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<br /> below grade (the existing shallow water table depth) During
<br /> excavation, two monitoring wells (MW1 and MW7) and all seven vapor
<br /> extraction wells were destroyed Also during excavation, six of
<br /> the remaining seven monitoring wells (MW2 , MW3 , MW4 , MW5 , MW8 , and
<br /> MW9) suffered various amounts of wellhead damage Documentation of
<br /> the soil excavation methods , sampling techniques, and the analyti-
<br /> cal results are presented in KEI ' s report (KEI-P88-1.013) dated
<br /> December 15 , 1988 As previously stated, during the excavation
<br /> activities it was necessary to destroy two monitoring wells, MW1
<br /> and MW7 The wells were destroyed on September 25 , 1988 , after
<br /> permits were obtained from the SJCPHS .
<br /> KEI concluded that both the source of the contamination and the
<br /> majority of the contaminated soil had been removed from the site,
<br /> and that it was necessary to determine the extent of ground water
<br /> contamination It was also concluded that KEI would prepare
<br /> proposals , as necessary, for well repair and abandonment, installa-
<br /> tion of additional monitoring wells, and subsequent ground water
<br /> remediation (if warranted)
<br /> On November 29 , 1988 , an attempt was made to obtain ground water
<br /> samples from the then existing monitoring wells However, most of
<br /> the wellheads were found to be damaged during soil excavation
<br /> Wells MW2 , MW3 , MW4 , MWS , and MW9 were in need of repair Although
<br /> damaged, access was gained to most of the wells Wells MW4, MW6 ,
<br /> MW8 , and MW9 were essentially dry, while only 2 5 to 6 4 gallons of
<br /> water could be purged from MW2 , MW3 and MW5 . Based on the lack of
<br /> rainfall and the subsequent drop in elevation of the ground water
<br /> table at the site, it was decided by Unocal and KEI to attempt to
<br /> sample the wells later in the winter
<br /> On February 24 , 1989 , an attempt was again made to sample as many
<br /> existing monitoring wells as possible Only wells MW2 , MW3 , MW4,
<br /> and MW5 were sampled Monitoring well MW6 was dry, MW8 contained
<br /> approximately one to two gallons of water and did not recharge
<br /> sufficiently to be sampled after purging, and MW9 was covered with
<br /> soil (prior to excavation, MW9 had also been dry)
<br /> Water samples were collected from wells MW2 , MW3 , MW4, and MW5 on
<br /> February 24 , 1989 The water samples were analyzed at Sequoia
<br /> Alla-L Cal Laboratory in nedirv'v Vd amity, Cuii9___, a, fVr total
<br /> petroleum hydrocarbons (TPH) as gasoline, benzene, toluene,
<br /> ethylbenzene, and xylenes (BTEX) , and EPA method 601 constituents
<br /> The analytical results are summarized in Table 3 The results of
<br /> the first quarter of monitoring and sampling of these wells
<br /> Performed by KEI are presented in KEI ' s report (KEI-P88-1013 -QR1)
<br /> dated March 17 , 1989
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<br /> KEI-Pgg-1D13 APA
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