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GeologualTecluucslxc Page 20 Site Conceptual Model Report Project No 724 2 May 2,2005 t encroachment is primarily occurring in the deeper aquifer, but not as severely in the water table and intermediate aquifer levels • The TPH-G levels present in the wells associated with Morita Brothers (<50 — 1580 ug/I) attenuate to non detectable levels within 220 feet east of the site No groundwater receptor was located down gradient of the site to the east within the 2000 foot survey radius • Gasoline oxygenates are present in the co-mingled plume but the quantity beneath the Morita Brothers site does not warrant remedial action • Operating a traditional groundwater pump & treat technology to address the residual ' groundwater plume would serve to accelerate the encroachment of the GASCO site plume onto the Morita Brothers property This applies to the less investigated UST releases to the immediate west of the GASCO site at 701 & 709 E Charter Way as well • The groundwater plume is unstable at the GASCO site GTI downloaded benzene and TPH-G data from the Geotracker's graphing function for well MW-1 at the ' GASCO site The chart is included in front of Appendix G and it demonstrates that the concentrations of these constituents are showing an increasing trend If this site cleanup is not addressed, it will continue to impact the Morita Brothers property ' 6.0 RECOMMENDATIONS Our recommendations are based on our knowledge of site conditions, and on the state and limitations of subsurface investigative technology Based on the conclusions outlined above, Geological Technics Inc recommends the following ' oThere is negligible risk to human health or the environment from the residual gasoline plume artifact present on this site Therefore, on behalf of Mr Frank Morita, GTI ' requests that the site closure be granted ' 7.0 LIMITATIONS This report was prepared in accordance with the generally accepted standard of care and ' practice in effect at the time Services were rendered It should be recognized that definition and evaluation of environmental conditions is an inexact science and that the state or practice of environmental geology/hydrology is changing and evolving and that standards existing at ' the present time may change as knowledge increases and the state of the practice continues to improve Further, that differing subsurface soil characteristics can be experienced within a small distance and therefore cannot be known in an absolute sense All conclusions and recommendations are based on the available data and information. The tasks proposed and completed during this project were reviewed and approved by the local regulatory agency for compliance with the law No warranty, expressed or implied, is made