SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Mr. Carl W. Knowles, Successor Trustee Page 4 of 5 Knowles Family Trust 23 December 2009 Former Roek Construction 102 S. Wilson Way As the discussion of contaminant concentration trends in the subsurface was not presented in the RCC by a properly licensed professional, the EHD will not comment on it in detail at this time; however, it should be noted that the EHD has concurred with GZA's interpretation that dissolved MTBE on your site is the result of on-site migration from unauthorized UST system releases on either the former Top Filling site or the Arco site, and by letter dated 23 February 2009, the EHD relieved you of any further sampling responsibility for monitoring wells MW-3, MW-4, MW-7, MW-14, MW-16A and MW-16B. The EHD has left some wells that contain MTBE on your sampling regimen because the EHD interprets other contaminants, for example 1,2- DCA, to be from your release. If it can be convincingly demonstrated to the EHD that any wells you still sample are predominantly impacted by one of the off-site releases, and that the information derived from such wells does not contribute to the proper management or characterization of your plume, the EHD will also remove them from your sampling regimen. To be clear, the EHD does not expect you to remediate the migrating MTBE plume or trespassing TPHg and BTEX from one of the off-site releases; in fact the EHD specifically noted in the directive by letter dated 31 August 2005, that MTBE was not a target contaminant of the directive to submit a work plan for interim groundwater remediation. Your directives are to address groundwater impacted by your unauthorized release, which is typically characterized by the presence of TPHg, BTEX, 1,2-DCA, and on occasion, locally by ethylene dibromide (EDB). Over a 2-year period, from November 1997 to December 1999, a soil vapor extraction unit operated on your site, removing an estimated 12,700 pounds of contaminants. GZA estimates that an additional 750 pounds of hydrocarbons resides in soil above the groundwater and 15,000 pounds resides in soil saturated by groundwater. The residual 22,500 pounds of contaminants is apparently the source of contaminants that continually flux into groundwater, maintaining the plume of groundwater impacted by TPHg, BTEX and 1,2-DCA. No active remediation has occurred at the site for the last 10 years despite efforts by the EHD to address the impacted groundwater issue; such efforts go back as far as 20 July 2001 when the EHD recommended by letter that the feasibility of in situ air sparging and groundwater extraction should be evaluated and directed by letter dated 04 January 2002 evaluation of ozone injection. More recently the EHD directed by letters dated 31 August 2005 submission of a work plan for interim groundwater remediation, 26 October 2006 preparation of a corrective action plan or feasibility study, and 23 February 2009 submission of a corrective action plan and reinitiate soil vapor extraction; none of these directives have been met to date; the due dates have been ignored. GZA recommended in a report dated 06 October 2005 repair and reinitiating operation of the soil vapor extraction unit on your site, which the EHD approved by letter dated 26 October 2006, but the approved scope of work has not been implemented. The EHD does not understand why the unit could not be repaired and returned to operation over the three-year period that has elapsed since the EHD approved the GZA recommendation. Finally, the EHD cannot comment in detail on the applicability of the Chevron case that resulted in the State of California State Water Resources Control Board Order WQO 2004-0005, as the applicability of that case was not presented by a properly licensed profession showing how the site-specific details of the Chevron case are closely matched by your site characteristics. The Chevron case circumstances in the Order are given in general terms, and the details of the two sites' hydrogeology, contaminant species, concentrations and masses are not provided that would enable the EHD to evaluate the applicability of WOO 2005-0005 to your site. If you wish further consideration of this issue, have your consultant submit a report that supports your argument. You should be aware that the EHD believes that your site data overwhelmingly Site Closure Request Response 1209