SITE INFORMATION AND CORRESPONDENCE

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Mr. Andrew Smith - 2 - 20 March 2002 3. The Work Plan proposed a survey of existing monitoring wells and based on investigation results, stated that H&H Marina would propose additional monitoring wells. The Report does not include this information. 4. The Report suggests that the pollution on site is mostly from the former underground storage tanks (USTs). The Site Model Section supports this explanation by showing the vaned distances and concentrations of the constituents of concern (CDCs)in relation to their proximity to the former USTs, and stating that constituents migrate at varying rates (i.e, methyl tertiary butyl ether migrates faster than benzene). Board staff does not agree with the assessment of the source of pollution. The three USTs were removed in October 1991. The elevated levels of COCs suggests that the pollutants in soil and groundwater are much newer than 1991. Furthermore, the Report states that flow direction is both locally and seasonably variable. This variability could be the cause of the variable migration of COCs at the site. By 15 May 2002,please submit a work plan for an additional investigation to delineate the lateral and vertical extent of groundwater pollution. The work plan needs to address the above comments, include installation of monitoring wells,propose surveying all existing and proposed monitoring wells to mean sea level datum, and include a schedule to implement proposed work. The work plan should be prepared in general accordance with the attached Items To Be Included In A Site Assessment Work Plan. If you have any questions, you may contact meat (916) 255-3119 or by email at lewisd(o)rbSs.swrcb.ca.gov. DEVRA LEWIS Environmental Scientist Attachment cc: Ms. Margaret Lagorio, San Joaquin County Environmental Health Department, Stockton Mr. Brian Millman, Advanced GeoEnvironmental, Inc., Stockton