FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

The excavation was backfilled to within 3 feet of the finish grade with pea gravel and the remainder was backfilled with Class II baserock and compacted as required by Ms.Turkatte of PHS-EHD. Copies of the weight tickets for the fill materials are included in Appendix D. DISCUSSION The former underground storage tank displayed evidence of corrosion and soil samples B-1 and B-2, directly under the tank, displayed the highest level of TPHG and Benzene. However, these concentrations are low and the BTEX components display a degraded amount compared to TPHG and TPHD concentrations. The samples at the perimeter of the excavation show that contaminants were not detected. The lack of contaminant distribution in perimeter sample locations, together with the lack of floating product or sheen on the groundwater or lack of detectable Gasoline or its constituents in this water in the pit indicates in our opinion that the leakage was limited. Groundwater monitoring wells do not exist at this site, however, the site gradient is surmised to be very flat and possibly a net inward flow gradient given the proximity of the river level, dikes and elevation. If a significant quantity of fuel was lost, residual concentration would be expgcted on the capillary fringe samples. However, the absence of petroleum containments in the perimeter samples suggests incidental leakage and minimal to no movement CONCLUSIONS AND RECOMMENDATIONS An underground storage tank was located and removed by the Trust from a parking area on Kings Island. The Trust delayed contacting the agency, but solicited advice from Wright regarding a course of action. Wright informed the Trust that the agency must be notified and pointed out the need to place soil and the tank on plastic. Wright later assisted the Trust in tank and soil characterization, permitting and agency-supervised soil sampling and chemical analysis. Soil samples and a water sample taken at PHS-EHD regulator request indicated that very low concentrations of TPHG, TPHD and BTM were observed in samples collected directly beneath the tank. Excavation perimeter and water samples revealed that contaminants were not detected. In our opinion, the data indicates that the tank leaked a limited quantity of gasoline fuel, which penetrated only a very short distance beneath the tank. The source has been removed and the excavated soil characterized and disposed of offsite rather than being used for fill. Evidence of a contaminated groundwater plume is lacking based upon this data and the assumed very flat gradient on the island and in the river vicinity. Wright suggests that no further action to taken to investigate the release from the UST. If after reading this report, PHS-EHD concurs that this site does not warrant further corrective action, then the Trust should request PHS-EHD to provide a letter stating that no further soil or groundwater samples are required and will recommend closure of this site to the RWQCB.