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yT 7„ :C After depth measurements, each well was purged of standing water. PVC bailers and submersible purge pumps were used to remove between 3 and 5 well volumes of water from each well. The wells were purged to stabilize pH,temperature and conductivity. Parameters were measured using an ICM water analyzer. Purge water was stored on-site.in DOT- approved drums. Monitoring well data sheets are included in Appendix C. After each well was stabilized, groundwater samples were collected. Samples were collected from each well using a new,*clean, disposable plastic bailer and place in 40-m1 EPA vials and 1-liter amber bottles. The samples were placed in a chilled container and transported under chain-of-custody procedure to a McCampbell Analytical, Inc. (MAI) in Pacheco, California. Each sample was analyzed for TPH as gasoline, TPH as diesel and BTE&X in accordance with EPA methods 5030 and 602, respectively. No TPH asg asoline or BTE&X were detected in any of the samples collected,on.July 19, 1994. However, TPH as diesel was detected in samples from MW-4, MW-5, MW-7 and MW-8 at concentrations of 100 ppb, 74 ppb, 90 ppb and 90 ppb, respectively. The laboratory report indicated that the petroleum hydrocarbons detected,although reported as diesel,were actually in the motor oil range. Mr. Ed Hamilton, Laboratory Director for MAI„confirmed,, the motor oil interpretation. The laboratory report, chain-of-custody and chromatagrams (provided by MAI) are included in Appendix D. The analytical, results.are summarizedin Table 5. The relative elevation of theg roundwater in each well was calculated by subtracting the water depth from the surveyed casing elevation (Table 6). Groundwater gradient is northeast with a slope of approximately 0,0032 ft/ft. Figure 3 illustrates the relative groundwater elevation and gradient direction. Historical gradient directions are included in ' Table 6. 4,0 CONCLUSIONS AND RECOMMENDATIONS l 4.1 Hydrocarbon Impacted Solt ' As stated in previous reports concerning the Yellow Submarine site, hydrocarbon impacted soil remaining on-site is very minimal. Figure 4 is a cross-section of the site from MW-8 (south) to MW-6 (north). The cross-section illustrates the generalized soil type and remaining impacted soil, both on-site and beneath Harding Way. ' From Figure 4, we can estimate the volume of impacted soil remaining on-site and beneath Harding Way; from the volume of impacted soil, the volume of remaining hydrocarbons can be calculated. ' On-site, the remaining impacted soil can be defined by the cross-sectional area that extends p�bgsl/rd'a Sarvm.Ek 8 67}-yY61.LDW SIJ6GSR,A1 O