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Conclusions and Recommendations Three exploratory borings were drilled and sampled around the former underground tank pits in Sixth Street. Soil sample data from 1990 showed high levels of TPHD in soil at that time. Soil boring samples collected in February 2003 showed that contaminants contained TPHG and TPHD in soil samples near the capillary fringe, with the highest values in B-2. Groundwater samples from the borings showed, TPHG and TPHD in Borings B-2 and B-3. These samples together with the inferred northerly groundwater flow direction indicate that a dissolved plume is assumed to extend across what is now the Delta Disposal property line. An access agreement to drill a borings to collect data on the private property was not reached at the time of this work. It is our opinion that on the basis of the data presented herein, the PHS EHD may likely require additional assessment regarding the extent of the dissolved plume. Additional assessment soil and groundwater data would then be used for monitoring program and site cleanup approach. Possible additional assessment work might include: • A historic review of possible air photograph and map sources to the south at the former rail yard that could contribute to the dissolved plume observed in the street. • Advancing an exploratory boring on the south side of Sixth Street to ascertain whether a contributing source might be present. • Additional subsurface site assessment on the Delta property to collect information on aquifer physical properties and extent of dissolved plume. • Installation of groundwater monitoring wells and initiating a quarterly groundwater- monitoring program. A review, of the results of this reconnaissance assessment should.be made with the PHS EHD representative regarding the possible additional site assessment approach to address the property owners and PHS EHD concerns. Wright recommends that these results should be reported to the PHS EHD in a timely manner. Page 4 of 6