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section D-E} Sample CPT-3-118' appears to be from a finer-grained interval that may be outside of this possible channel deposit No hydrocarbons were detected in CPT-3-118', but both TPH-g and TPH-d were reported in CPT- 1-114', and xylene was reported at 0 7 ppb Concentrations were about 4-10 times higher than those reported in the sample at 80 feet This is the reverse of the expected result The reason for this anomaly is uncertain at this time 4.0 SUMMARY AND CONCLUSIONS r The vertical and lateral extent of diesel and gasoline in groundwater within the Riverbank Formation was investigated by drilling six cone penetrometer borings in conjunction with regular quarterly monitoring of the five existing monitor wells The borings ranged in depth from 100 to 130 feet, and three separate water-bearing sand bodies were sampled A total of fourteen water samples were collected using hydropunch methods, in addition to the five well samples Eighteen samples were analyzed for TPH-d, ten were analyzed for TPH-g and BTEX, and three were analyzed for gasoline oxygenates Diesel was detected in six of the hydropunch samples and two of the well samples, and gasoline was detected in three of the hydropunch samples No gasoline oxygenates were detected The uppermost sand body in the Riverbank Formation, which is present at a depth of approximately 65 feet, is impacted by diesel at concentrations that range between 100 and 700 parts per billion in • seven of the eight samples that contained detectable concentrations These concentrations are reasonable and within historical ranges for the three monitor wells that are completed within this zone One sample, from the CPT boring nearest the former UST cavity, was reported to contain both diesel and gasoline at extremely elevated concentrations that are much greater than can be explained in terms of known soil concentrations The validity of that sample is questionable In general, the distribution of diesel follows the trend of the sand body Diesel was detected in the two hydropunch samples of the two deeper sand bodies in the boring nearest the UST cavity, but not in any other hydropunch or well sample These sand bodies are probably not impacted, except perhaps very locally near the UST cavity Thick, fine-grained, locally cemented aquitards separate each of the sand bodies and inhibit groundwater communication and contaminant migration, and are responsible for the downward dissipation of hydrocarbons in both soil and groundwater These aquitards can be confidently traced throughout the site area in both geologic logs and CPT logs i