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9 • ethylene dibromide and organic lead, should be provided with the Work Plan because they are not readily available. 60. Table B-2A, Analytical Method References for DDRW-Tracy Footnote (e) indicates that ammonia will be one of the anions analyzed by EPA Method 300.0. Although it is possible to analyze ammonia by ion chromatography, there is currently no EPA method for this approach. The ammonia ion would react with the carbonate-bicarbonate eluent used in EPA Method 300.0 and inaccurate results would be obtained. Either an alternative method should be selected or the modified method should be provided for review. 61. Tables B-6A to B-12A, Method Reporting Limit Tables A number of the analytes in these lists have detection limits well below those usually associated with the method. For example, for EPA Method 8240, carbon disulfide, 2- hexanone, and vinyl acetate detection limits will be difficult to achieve, and many of the Method 8270 solid limits and pesticide limits in water are lower than arc routinely achieved. This discrepancy should be noted and the table modified to explain the lower detection limits.2 62. Table B-7A, Method Reporting limit for Semivolatile Organic Compounds, Method 8270 Many of the detection limits in this table, especially for soils, are below what are typically achieved for environmental laboratories using EPA Method 8270. Sec the discussion above. Please explain this with a modification or footnote to the table. 63. Table B-19-A, Surrogate Spike Recovery Acceptance Criteria It is not clear to what analysis footnote (a) refers, nor how this footnote applies. For example, does this statement mean that 15% of a given type of sample may have 2 Laboratory limits should be compared to the limits in SW-846. Where detection limits are more than a factor of 5 below the practical quantitation limit, the procedures which will be followed to obtain these limits should be discussed. Alternatively, the Work Plan should require that a detection limit verification standard be analyzed. This standard should be within a factor of 2 or 3 of the detection limit in the tables, and should display a reasonable signal to noise ratio (such as 5:1) for the detection limits to be considered valid. The discussion in the footnotes to Tables B-9A to B-12A suggests that the limits may reflect instrument detection limits rather than method detection limits. If this is the case, this and the other tables should make this clear. Although the Work Plan makes it clear•what the rationale is for needing low detection limits, the Work Plan should also make it clear how these limits are to be achieved. USEPA/R9 12 Apr 93 13/19 i