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Mr.M. Scott Mansholt—CEMC First Quarter 2006 Groundwater Monitoring and Sampling Report April 18,2006 US Can-Welty Road Page 4 of 5 • BTEX using EPA Method 802113; and • PAHs using EPA Method 8270C SIM. Samples were not collected from wells MW-1 and MW-2 because of the presence of SPO sheen or odor and the presence of petroleum-absorbing(oleophilic) socks in these wells; and no samples were collected from well MW-4 due to insufficient water volume in the well for sample collection. No TPHg or BTEX were detected in the groundwater samples. No TPHd was detected in MW-5. TPHd at concentrations of 1,000 and 66 gg/L were detected in wells MW-3 (March 30, 2006 results are reported) and WFSMW-1,respectively. No PAHs were detected in the groundwater samples from MW-5. PAHs were detected in the groundwater sample from well MW-3 at concentrations ranging from 0.024 to 0.25 gg/L. Pyrene was detected in WFSMW-1 at the 0.025 gg/L. All detected PAHs were below their respective Preliminary Remediation Goals (PRGs) for direct exposure to tap water.2 The groundwater analytical results are presented in Tables 2 and 3. A petroleum-hydrocarbon distribution map is presented as Figure 4. A copy of the laboratory analytical report is presented as Attachment B. QUARTERLY OLEOPHILIC SOCK REPLACEMENT An oleophilic sock was installed in well MW-1 due to the presence of SPO in the well and an oleophilic sock was placed in MW-2 due to the petroleum odor detected from the well. The socks in MW-1 and MW-2 have been monitored and replaced as necessary on a quarterly basis. During the first quarter 2006,the oleophilic sock from MW-1 was weighed but not replaced,and approximately 4 ounces (0.04 gallon) of SPO had been absorbed. The oleophilic sock from MW-2 was also weighed but not replaced, and approximately 2 ounces(0.02 gallon)of SPO had been absorbed. A summary of SPO thickness measurements is included in Table 1. QUALITY ASSURANCE/QUALITY CONTROL (QA/QC) All field procedures were conducted in accordance with SAIC's Quality Assurance and Quality Control Sample Collection, Handling, and Analysis 3procedures. No sample was received by the laboratory outside of acceptable temperature or pH limits. In addition to routine laboratory QC sample analysis, four field QC samples were analyzed for this event in accordance with SAIC's standard field procedures: a trip blank(QA-T); a rinsate blank(QA-R); duplicate (MW-5D); a matrix spike(MW-5MS); and matrix spike duplicate(MW-5MSD). No indication of potential cross contamination was identified in the sample analyses. No THPd, TPHg,BTEX,or PAHs were detected in the laboratory blank sample. The field duplicate, surrogate QC,matrix spike, and matrix spike duplicate sample results associated with the samples collected on February 14, 2006,were within acceptable ranges,except for the TPHd (with silica-gel preparation) surrogate recovery for MW-3 that was slightly out of the specification range. MW-3 was re-sampled on March 30, 2006 due to potential matrix interference noted from the analysis of the February samples. The lab compliance QC and the surrogate QC results associated with the March 30,2006 samples met QC requirements. The laboratory considers the sample results acceptable and useable. 2. The PRGs are risk-based tools for evaluating potential exposure risk to human health at the screening level and for establishing preliminary cleanup goals. 3. SAIC,2006. Quality Assurance and Quality Control Sample Collection,Handling,and Analysis. January (Update).