SITE INFORMATION AND CORRESPONDENCE

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Mr. Gregory Torlai, Jr - 3 - 3 April 2008 H & H Marina 0 • months in 2007 when influent samples were taken. Influent MTBE concentrations are variable, but show an overall stable trend in 2007 and are greatly reduced since 2005. The existing interim system was originally designed to address groundwater within a limited area of impact from the UST spill. The data in Tables 3 and 4 of the Report show that significant progress has been achieved in this respect. However, the MW-14 and MW-4 data show H & H Marina must upgrade the interim system to a permanent system in order to exert site-wide, hydraulic control. 2. We are concerned that there is not sufficient data to ensure that proposed changes to the existing pump and treat system will be effective in attaining site cleanup. The proposed system modifications appear to be intended to address only the September 2007 spill. However, the ultimate goal of groundwater treatment is site-wide remediation to water quality objectives (WQOs). While we do not object to H & H Marina proceeding with their plan to continue efforts to mitigate the September 2007 spill, ultimately, the goal of the proposed system enhancements must be to cleanup the entire commingled plume. The data obtained from the site assessment should be used to provide the design basis for a permanent groundwater treatment system. The Site Assessment Report must also provide calculations showing that proposed improvements to the system will have the capacity to attain WQOs site-wide. If H & H selects pump and treat as a permanent remedy, the requested calculations must include the • optimum number of extraction wells needed to achieve site-wide remediation, • optimum locations of those extraction wells, • construction details of the extraction wells, • optimum pumping rates for each of these wells, • optimized design of a permanent treatment system. These calculations may be submitted as steady-state analytical solutions. 3. The 15 June 2007 Site Optimization Report recommended reconfiguring the electrical system to permit more continuous operation and increased groundwater extraction rates. Our 6 January 2008 letter concurred with this recommendation. The extraction rate, calculated from September to December 2007, averaged about 0.2 gallons per minute (gpm). This rate is consistent with historical trends, which typically vary from 0 to about 0.8 gpm. H & H must disclose whether the proposed electrical supply upgrade was implemented as planned, and if so, why the optimized extraction rates have not been realized. 4. The Report states that the groundwater plume currently consists of dissolved TBA recently released near the location of well MW-2. However, the groundwater data from MW-2 does not substantiate this statement. The data show that a sporadic TBA concentration increase occurred in June 2007, about 3 months prior to discovery of the spill. Subsequent observations have been significantly lower and include 410 ug/L in September and ND (<5 ug/L) in December 2007. Therefore, this statement appears to be erroneous. Unless increased TBA concentrations are noted in future observations, this statement should be removed from future reports.