Field X-ray fluorescence (XRF) chemical analyses were performed to efficiently and cost-effectively evaluate arsenic and lead concentrations in soils as part of CERCLA-driven remedial investigations at a former lead smelter. Sample preparation and analysis protocols, including extensive quality control (QC) requirements, were developed for the field XRF method that were accepted by the United States Environmental Protection Agency and other regulatory agencies. Over 800 soil samples from

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... mately 150 borings and test pits were analyzed using the field XRF technique during a three-week period. Measured arsenic and lead concentrations ranged over several orders of magnitude. Costs for using the field XRF technique were about 60 to 70 percent of the costs for traditional wet chemistry (acid digestion and spectrophotometric analysis) methods, which were also used to analyze selected samples for verification. Split samples analyzed during and immediately after the field investigation showed a good correlation between soil concentrations obtained using field XRF methods and concentrations obtained using laboratory analysis (both XRF and wet chemistry). Correlation coefficients (r 2 ) for split samples compared using linear regression ranged from 0.832 to 0.995. Split-sample comparisons were generally better at lower soil concentrations (<10,000 ppm arsenic, <15,000 ppm lead). Duplicate, blank, and control standard results for the field XRF method were within limits typically achieved by laboratory-based systems. Preparation study results suggested that increased levels of soil-sample preparation may not significantly improve data comparability. Overall, results indicated that the field XRF technique is a dependable method for "screening-level" investigations in which solids are differentiated based on order-of-magnitude differences in arsenic and ( or) lead concentrations. The field XRF method allowed rapid turnaround of analytical results while achieving data quality and comparability goals acceptable for a CERCLA remedial investigation.