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fol-b- 5 August 1992 <br /> (GeoAudit CV 30-34E3-1. 47) <br /> Page 5 of 6 <br /> 2) The lack of contamination in all soil samples, except those <br />' collected by Weiss Associates from MW-1, indicates that soil <br /> contamination was limited to the immediate vicinity of the <br /> former UST. This implies that downward migration of petroleum <br />' hydrocarbons exceeded lateral migration in the vadose zone. <br /> 3) It appears that contamination may have reached groundwater in <br /> the vicinity of MW-1 and subsequently migrated laterally along <br />' the capillary fringe to the other wells. <br /> 4) The highest levels of groundwater contamination reported to <br /> date were found in 14W-3 in 1987 . The lowest levels were found <br /> in MW-2 in 1987 . In 1992 , contamination levels in MW-4 and 14W- <br /> 5 were intermediate between those obtained in 1987 from the <br /> other wells. <br /> 5) Based on the north-northeast gradient in 1987 and the <br /> northwest gradient today, contaminated groundwater should have <br /> migrated from MW-1 and MW-3 toward MW-4 . However, <br /> contamination levels in MW-4 today are lower than those in <br /> either MW-1 or MW-3 in 1987, and floating product was <br /> encountered in MW-1 in 1991. These observations suggest that <br /> since 1987 , the contamination has not migrated far to the <br /> northeast.as. . Th.. ......tam z..a. �o.. may ..,...V.. rema�n4� JtatlV..alI , <br /> migrated to the northwest beneath the building, or dissipated <br /> somewhat over time. <br /> 6) In 1987, 'no total petroleum hydrocarbons were detected in MW- <br /> 2 , which was the most up-gradient well. In 1992 , a TPH <br /> concentration of 9. 6 ppm was detected in water from the <br /> replacement well (MW-S) is ' s now . geat <br /> well •+ r "d� awe <br />�� p • .�a• aced- s� ,��: <br /> 7) As previously suggested by Weiss Associates in their 1987 <br /> report, it is likely that withdrawal of groundwater from the <br /> City of Lodi Municipal Well #1, which is located approximately <br />' 350 feet east of the site, may have drawn down the aquifer and <br /> created the northeast groundwater gradient in 1987 . Since that <br /> time, Lodi Municipal Well #1 has been abandoned and the <br />�. (7Y•AH i Ant hAs ono h== rai�nrccri The rYr r7 i or � i c_ rrr.r <br /> more similar to the regional southwest gradient that is <br /> prevalent in the area. <br /> 8) The lateral extent of groundwater contamination has not been <br /> completely defined. The 1992 results indicate that <br />' contaminated groundwater extends to the southwest and north of <br />