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CLEARWATER <br /> G R O U P, I N C <br /> Envvanmentu7 Services <br /> hydrocarbons in the vadose zone are shown on the Hydrocarbon Distribution in Soil Map (Figure 5) <br /> Using this data the quantity of residual TPH-G in the vadose zone was estimated by Clearwater to be <br /> 7 28 gallons <br /> Conclusions and Recommendations <br /> The County indicated in a conversation with Clearwater in June 1998 that file closure would be <br /> considered if the results of the testing were consistent with recent events and if concentrations of fuel <br /> additives were not present or present in acceptably low concentrations <br /> The sampling and analysis completed during this recent phase of investigative activity completes the <br /> subsurface investigation at the subject facility The subsurface in the vicinity of the former source area <br /> has been investigated laterally and vertically, with testing results showing the soil and water beneath the <br /> site to contain only residual concentrations of hydrocarbon constituents, and no detectable concentrations <br /> of fuel additives The results of this phase of testing augment and confirm the results of the extensive <br /> i groundwater monitoring program that has been in place for the past eight years <br /> b� <br /> The results of this phase of investigation document the following facts <br /> 1) The extent of contamination in the soil has been thoroughly evaluated and defined in all directions <br /> The remaining contaminants in the soil are minimal and amount only to 7 gallons of hydrocarbons <br /> Monitoring results demonstrate that these residual contaminants are stationary, and pose no risk to long- <br /> I <br /> term groundwater quality <br /> 2) The groundwater has been monitored extensively for the past eight years, indicating that contaminant <br /> concentrations are declining steadily in all'wells installed The boundary of contaminants in the <br /> groundwater is defined in all directions The residual contaminants in the groundwater is estimated to be <br /> less than 0 40 gallons <br /> I <br /> Given these facts, and the historic detection of only low concentrations of contamination, Clearwater <br /> ' concludes that the potential threat to groundwater quality or other sensitive environmental'receptors does <br /> not appear to be a significant concern, and therefore recommends that no further investigative,efforts be <br /> invested in this site This file should be closed following proper abandonment of all monitoring wells <br /> I <br /> I , <br /> Page 151 <br />