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FOURTH QUARTER,2002 GROUNDWATER MONITORING REPORT AND ADDITIONAL ASSESSMENT REPORT JAMAR OIL DISTRIBUTION MARCH 2003 The MTBE levels are quite different between the 65-foot sample (3,900 gg/1) and the 96-foot sample(41 gg/l) The TPH G, BTEX, TBA, and 1,2-DCA levels are also significantly different between the two higher permeability zones This upper hydrogeologic unit is where monitoring wells MW-1 through MW-5 are screened The depth to water was 64-feet bgs in MW-4 at the time of sampling The CPT-2 boring log analysis is less definitive There is a relatively thick hydrogeologic unit beginning at approximately 100-feet bgs and what appears to be a small hydrogeologic unit between approximately 68 and 71-feet bgs Groundwater was encountered at 65-feet bgs while drilling the adjacent geoprobe, HP-2 The similarity of the analytical data taken from the two groundwater samples in HP-2 indicate one thick hydrogeologic unit instead of two distinct units MTBE was reported at 3,200 µgll 65-feet bgs and at 2,500 µg/1 100-feet bgs 1,2-DCA and TBA results for the two samples from HP-2 were also similar Because of technical difficulties between the CPT rod and the CPT computer program, the boring log data below approximately 60-feet bgs in CPT-3 is not as definitive as that for the other two CPT logs As such, the CPT logs indicate two separate hydrogeologic units in the area beneath CPT-3, a smaller unit between approximately 59 and 70-feet bgs and a larger unit beginning approximately 94-feet bgs Initially, the geoprobe drilling was stopped at approximately 65-feet bgs based on the CPT log and the depth to water in the onsite wells Only a small amount of water came into this hole after more than 12 hours of leaving the hole open Groundwater was encountered at 96-feet bgs in the lower hydrogeologic unit The analytical data for HP-3 reported TPH D at 120 µg11 in both the upper and lower samples as well as minor amounts of toluene and MTBE MTBE was reported at 7 0 µg/l and 3 1 µg/l in the two samples It should be noted that the groundwater flow direction, based on the onsite wells, is to the southeast which is where HP-3 was located It appears that the groundwater impacts found beneath HP-2 may originate at the subject site while the soil and groundwater impacts found beneath HP-3 may be originating from the former service station on the southwest corner of Main St and Oro Ave, based on the fact that MTBE Z impacts were found in all three soil samples from HP-3 but none of the soil samples from HP-2 ' Also, the MTBE levels found in groundwater samples from HP-2 were stmilar to those found m2 HP-1 but not to those from HP-3 ` Figures 9 and 10 are cross sections showing the geologic data between CPT-1B and CPT-2 and between CPT-1B and CPT-3, respectively TPH G, TPH D, benzene and MTBE groundwater data, as well as groundwater level data are included on the cross sections to show the relative similarity in the depths of the groundwater zones and the dis-similanty between the groundwater data in HP-3 as compared with HP-1 and HP-2 11