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Dividend Development Company July 22. 1991 Report of Findings - North Parcel Page 13 DISCUSSION OF THE DATA:. Seven 7( ( ) groundwater monitoring wells were drilled an the North Parcel (MW-1 through MW-7) . The Drilling Map, Appendix A shows the location of these wells. Laboratory analyses of soil samples indicate contamination in the immediate area of the underground pipeline placed in the Southern Pacific Railroad Easement and bounding the site along West Byron Road. Contaminated soils were detected in MW-21 MW-3, MW-4, MW-6, and MW-7 at six to fourteen y feet ' (6 ' to 141 ) below grade. MW-1 is located at Site 1, the UST siteFi ure 2 ( g Appendix A) . The other wells are located at Site 2, adjacent to the pipeline site (Figure 2, Appendix A) . Monitoring well #1 shows no indication of contamination. However, i' the pipeline site is positively identified as an area of contamination. The soil at Site 2 is composed predominately of clay which will retard lateral contaminant migration. Monitoring well #5 shows no detectable levels of petroleum contamination, thus defining the maximum migration northward from the pipeline at less than two hundred feet (<2001 ) . Laboratory analyses ofthewater sample from MW-2 indicate up to approximately thirty-six parts per million (36 ppm) of dissolved hydrocarbon contamination. Free floating product, approximately two inches (211) thick, was also observed in MW--2. On the other hand, MW-1, MW--3 , MW-4, MW-5, MW-6, and MW-7 indicate no detectable i levels of petroleum hydrocarbon contamination thus indicating limited migration. I' Petroleum hydrocarbon vapor concentrations in MW-2 , MW-4, and MW-6 in the contaminated region of the site were five (5) to ten (10) I, ppm in MW-2 and MW-3 and forty (40) ppm in MW--6. Sustained vapor levels in MW--2 and MW-3 were less than five (5) ppm and less than twenty (20) ppm in MW-6. a Toxic Technology. Inc.