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Geological Tee6utics lnc. <br /> Page 12 <br /> City of Escalon <br /> Project No.: 750.2 <br /> y May 16,2005 <br /> �, • The small amount of residual contamination will likely attenuate to background <br /> conditions. <br /> • Portions of the site and adjoining properties not covered with buildings are covered <br /> with asphalt or compacted base rock (on-site), thereby limiting vertical migration via <br /> filtration. <br /> C • Groundwater quality parameters, including DO & ORP measurements, demonstrate <br /> that natural attenuation has been active at this site since contaminant release. <br /> LTPH-G Contamination <br /> • An estimated 56 gallons of residual TPH-G contamination remain in the soil. This <br /> estimate does not include soil removed during investigation activities nor does it <br /> Laddress natural attenuation. <br /> • The February 16, 2005 groundwater-monitoring event reveals that all of the site's <br /> monitoring wells are non-detect above laboratory reporting limits. <br /> �,, • There are no sensitive receptors within at least 1,600-feet of the site <br /> • Portions of the site and adjoining properties not covered by structures are capped by <br /> C asphalt,compacted base rock or concrete making migration by infiltration unlikely <br /> L <br /> MtBE Contamination <br /> • Historically, MtBE was only detected in one groundwater-monitoring well (MW-1). <br /> That monitoring well has been non-detect above laboratory reporting limits for MtBE <br /> over the last twelve consecutive quarterly groundwater-monitoring events. <br /> L • The.most recent soil samples, collected during October 2003, showed no traces of MtBE above laboratory reporting re ortin limits. <br /> 4.0 LIMITATIONS <br /> LThis report was prepared in accordance with the generally accepted standard of care and <br /> practice in effect at the time Services were rendered. It should be recognized that definition <br /> and evaluation of environmental conditions is an inexact science and that the state or practice <br /> L of environmental geology/hydrology is changing and evolving and that standards existing at <br /> the present time may change as knowledge increases and the state of the practice continues to <br /> improve. Further, that differing subsurface soil characteristics can be experienced within a <br /> small distance and therefore cannot be known in an absolute sense. All conclusions and <br /> recommendations are based on the available data and information. <br /> LThe tasks proposed and completed during this project were reviewed and approved by the <br /> local regulatory agency for compliance with the law. No warranty, expressed or implied, is <br /> Lmade. <br /> L <br /> i <br /> l� ` <br />