SITE INFORMATION AND CORRESPONDENCE

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OEOMATAIX Product Removal Geomatrix began quarterly product removal from on-site wells REW-2 and REW-3 in October 2001; product removal activities were assumed by SAIC in March 2003. SAIC began quarterly product removal in November 2004. Since October 2001,the estimated amount of product removed from well REW-2 and REW-3 is 16.53 and 22.13 gallons,respectively. 3.0 DATA EVALUATION AND CHEMICALS OF POTENTIAL CONCERN Data evaluation is the process of analyzing site characteristics and analytical data to identify data of sufficient quality for inclusion in the risk assessment and,based on these data, to Iden- tify COPCs. This section of the HHRA describes the methodology that was used to evaluate and select COPCs. 3.1 DATA USABILITY As discussed in Section 2.0, soil and groundwater samples have been collected during multiple phases of investigation by various consultants. As indicated above, a HHRA using historical soil and groundwater data was prepared by Dames and Moore and approved by DHS in 1990. Because historical soil samples may no longer represent current or future soil conditions at the site as a result of possible grading activities that were likely conducted after the completion of the 1990 HHRA,only the most recent soil data(Geomatrix, 2003)were considered in this evaluation. Soil samples collected in 2003 also were analyzed using the most current analytical techniques, thereby improving the sensitivity of quantifying concentrations of constituents in soil. In general,total petroleum hydrocarbons, quantified as crude oil(TPHc) and polynuclear aromatic hydrocarbons (PAHs)are the primary chemicals detected in soil at the site. The analytical results for chemicals detected in soil are presented in Table 1. For groundwater, analytical results from the most recent round of groundwater sampling in February 2005 were included in the data evaluation process; this data was used because it best represents both a current and a conservative estimate of future groundwater conditions at the site. Analytical results for groundwater from locations outside the periphery of the site, such as wells E, F, and REW-1,were not included in the evaluation because these monitoring wells are located outside the site boundary. 3.2 IDENTIFICATION OF COPCS COPCs for the HHRA are identified in this section. COPCs are generally defined as those chemicals that are most likely to be of concern to human health. All chemicals detected in soil, except TPHc,were conservatively considered as COPCs (Table 1). For the purposes of this 1:\Doc Safe\7000s\7065.001\HRA\HHRA Report Am 6