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' � • Mr.M. Scott Mansholt—CEMC March 31,2005 Site Investigation Work Plan, Mountain House Site#6 Page 4 of 5 PROPOSED ANALYSES ' SOIL SAMPLE ANALYSES Soil samples from selected borings will be collected from depths that coincide with affected intervals ' observed in previous borings or from the most affected soil interval encountered in new borings. Selected soil samples will be submitted to Lancaster Laboratories (Lancaster) in Lancaster,Pennsylvania(ELAP# 2116),under proper chain-of-custody protocol. Selected soil samples will be analyzed for benzene, toluene,ethylbenzene and xylenes(BTEX)by EPA Method 8021B,TPHc by EPA Method 8015 modified, and polynuclear aromatic hydrocarbons(PAHs) by EPA Method 8270C Selective Ion Monitoring(SIM). Following completion of the soil borings,the open boreholes will be destroyed according to SJCPHS requirements. GROUNDWATER SAMPLE ANALYSES SAIC will obtain grab groundwater samples from selected borings and submit them to Lancaster under ' proper chain-of-custody protocol for the following chemical analyses: BTEX by EPA Method 826013; TPHg and TPHd by EPA Method 8015 modified; TPHd by EPA Method 8015 modified with silica-gel cleanup for positive detections by EPA Method 8015; and PAHs by EPA Method 8270C SIM. ' To facilitate the use of groundwater samples in a HHRA, SAIC recommends that detection limits for BTEX and PAHs be requested from the laboratory that are lower than the EPA Region IX Preliminary Remediation Goals(PRG). The benzene detection limit for use in a HIIRA should be less than the EPA ' tap water PRG of 0.34 µg/L. A detection limit of<0.1 µg/L should be requested for benzene. A detection limit of<1.0 µg/L is adequate for toluene,ethylbenzene, and total xylenes. Groundwater detection limits for all PAH compounds should be requested at<0.01 µg/L except for benzo(a)pyrene and ' dibenzo(a,h)anthracene,which should be requested at<0.005 µg/L to ensure the grab groundwater data is adequate for use in a HHRA. QUALITY ASSURANCE/QUALITY CONTROL This investigation will be conducted in accordance with SAIC SOPS Quality Assurance& Quality Control Sample Collection, Handling, and Analysis Guidelines(2005)and the CTA(Geomatrix 2005). One trip-blank water sample and one equipment-blank water sample will be collected and analyzed. Quality control samples will be analyzed for BTEX by EPA Method 826013; TPHg and TPHd by EPA Method 8015 modified; TPHd by EPA Method 8015 modified with silica-gel cleanup for positive ' detections by Method EPA 8015; and PAHs by EPA Method 8270C SIM, REPORTING AND SCHEDULE Upon completion of all field activities described above and receipt of all analytical results, SAIC will evaluate whether soil and groundwater has been delineated at the subject site and will prepare a subsurface investigation report summarizing the field activities and observations,the laboratory analytical ' results, and our conclusions and recommendations. The subsurface investigation report will include the following: ' • Description of drilling methods and boring logs; • Description of soil and groundwater sampling methods and procedures; • A summary of soil and groundwater analytical test results; • A site plan with new boring locations; • A tabulation of soil and groundwater data;