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Data Usability Summary Page 3 of 4 Representativeness Representativeness was assessed through the evaluation of method blank samples,trip and equipment blank samples, chain-of-custody forms,preservation, and holding times. Method Blank Results TPHd were detected at 34 micrograms per liter(gg/L)in the method blank associated with the samples in this data set. TPHd were detected in samples QA-R-070123 and MW-5-W-070123 at 86 gg/L and 56 gg/L,respectively. The results were qualified U as non-detect because the concentration are within five times the concentration detected in the method and are likely due to contamination. TPHd were also detected in samples WFSMW-I-W-070123 and field duplicate WFSMW-I-WD-070123 at 390 gg/L and 340 gg/L,respectively. These results were not qualified because the concentrations are greater than five times the amount detected in the method blank and are not biased from laboratory contamination. Sodium was detected in the method blank associated with sample MW-5-W-070123 at 519 gg/L. The result in the field sample was 111,000 gg/L. No qualifier was applied to the result because the concentration in method blank is negligible compared to the concentration detected in the field sample. Field QC Results One equipment rinsate blank, QA-R-070123,was submitted with the samples. TPHd and naphthalene were detected below the laboratory LOQs. TPHd were detected in the associate method blank, and the result in the equipment blank was qualified U for the contamination. Naphthalene was detected at similar concentrations that were also below the laboratory LOQ in samples MW-5-W-070123,WFSMW-I-W- 070123, and field duplicate WFSMW-I-WD-070123. The detection of naphthalene in the equipment blank indicates the sample results were likely biased due to introduced contamination during sample collection,handling, and/or analysis. The naphthalene results were qualified U as non-detect to indicate the detections are not representative of field conditions. Chain-Of-Custody Forms Sample analytical results were evaluated for agreement with the chain-of-custody form. Based on the evaluation, all samples were received at the lab in the appropriate containers and in good condition with the chain-of-custody form filled out properly. Preservation and Holding Times Samples were preserved in the field as appropriate and were received at the laboratory within the acceptance temperature criterion of 4+2 °C. The samples were prepared and analyzed within specified holding times. Reporting Limits Data reported for this sampling event were reported with the laboratory MDLs. The MDL represents the lowest concentration point where an analyte can be positively identified,but the quantitation is an estimate. The LOQ is the lowest concentration of an analyte in a sample that the laboratory can report with precision and accuracy. Analytes that were reported between the MDL and LOQ for this data set were qualified J as estimates. Laboratory Fuel Notes for TPHd Analysis The laboratory noted that the observed hydrocarbon fuel pattern for TPHd analysis in samples QA-R- 070123 and MW-5-W-070123 were not typical of#2 fuel/diesel and the reported results were due to individual peaks eluting in the diesel-carbon range. The lab also noted that fuel patterns for WFSMW-1- W-070123 and WFSMW-I-WD-070123 included#2 fuel/diesel, an additional pattern that eluted later in the carbon range, and individual peaks. These samples were also silica-gel cleaned prior to the analysis and TPHd were not detected after the silica-gel cleanup. This indicates the TPHd results could be biased '�iAajE7. From Science to Solutions