ARCHIVED REPORTS XR0012868 - Laserfiche WebLink

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I Trichloroethene in the water, all soil samples were ND This ' minor contamination may be due to another source, but is most likely associated with the large Nomellini plume which exists to the east ' PLATE VIIE - lines of equal concentration of TPHg - confirms the existence of two separate plumes Water samples from MW-9 measured 111., 000 ug/L, although free product was not observed ' during collection Soil samples at 1016" measured 1, 600 , 000 ug/L, 1, 120, 000 ug/L at 1516 " and 3 , 090, 000 ug/L at 2016" ' PLATE VIIF shows lines of equal concentration of TEPH Diesel was the only compound identified, and only from MW-4 This agrees with prior data, since that well is near the site of the removed diesel UST' s ' CONCLUSIONS ' Based upon the results of this latest work, the following conclusions appear to be valid 1 Based upon data obtained to date, the hydraulic gradient is to the east/northeast, which agrees well with other data However, the presence of the Nomellini plume beneath this site indicates that historically the gradient has been divergent 2 The groundwater plume caused by leaking UST' s on the Nomellini property to the east of this site exists at least as 17 ' far west as MW-4, and most likely to MW-3 and possibly beyond_— , The minor amount of contamination measured in MW-7 may also be a result of that plume A "halo" effect may account for the presence of benzene in MW-3 , (toluene, ethylbenzene, xylenes & ' TPHg were non-detect, ) although the benzene could also be from the westerly source 3 A major source of gasoline exists to the west of the Indepen- dent Trucking facility MW-9 , which is located at 1245 West Charter Way, approximately 45 feet west of , and upgradient from the subject site, measured extremely high levels of BTEX & TPHg, ' but no heavier compounds The gasoline compounds detected in soil and water samples during removal of the septic system and leach lines, soil borings, and existing monitoring wells between ' the shop building and property line at 1145 W Charter Way appear to be due to this new source 4 Residual soil contamination remaining after removal of the ' three diesel UST' s has been impacted by gasoline compounds from n the Nomellini site . Additional excavation cannot be justified 11