ARCHIVED REPORTS_XR0010429 - Laserfiche WebLink

Home Browse Search

4. 1 .1 Conclusions - Washpad Minor soil contamination exists under the aircraft washpad. Contamination is probably localized under cracks and expansion aoints . The likelihood of contaminant migration laterally beyond the edge of the pad is slight. The TPH detected at 10 feet in boring 2-3 was identified by the analytical laboratory as motor oil. The presence of this relatively heavy hydrocarbon at such a depth, under the hardpan layer, particularly in the absence of detectable TPH at 2 feet and 7 feet, is unusual. Recommendations for verifying this TPH contamination are presented in the next chapter. 4.2 Clarifier Three 10 foot deep hand augered borings were successfully completed around the clarifier perimeter. Apparent contamination based on soil discoloration and odor was observed in the upper 3 feet of boring 3 and the entire depth of boring 1 . Clarifier soil sample data for m8015 (petroleum hydrocarbons) and 602 (purgeable aromatics) analyses is summarized in Table 2 . All analytical results for 82.70 (semi-volatile) analyses were non- detectable with the exception of 2-Methylnaphthalene. This compound was detected in all three boring 1 samples as indicated below: Sample C-1 -2: 590 PPB 2-Methylnapthalene Sample C-1 --5 : 720 PPB 2-Methylnapthalene Sample C-1 -10 : 16, 600 PPB 2-Methy1napthalene Original laboratory report forms indicating minimum detection limits for each constituent are presented in the appendix. No hardpan layer was encountered in any of the borings . Boring logs are presented in the appendix. 4.2. 1 Conclusions - Clarifier Moderate soil contamination exists around the clarifier area. Contaminant concentrations are highest near the surface, however significant hydrocarbon and solvent levels extent to an unknown depth near the influent (western) end. No vertical barrier to downward contaminant migration was encountered at this site . Recommendations for further site assessment are presented in Section 5 . 2 . 16