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Tri-Regional Recommendations Page 12 of 24 Appendix A Explanation for TABLE #2: MINIMUM VERIFICATION ANALYSES 1. As other methodologies are developed and accepted by the USEPA and the DHS,they may also be used if they have equal or better performance than the listed methods. 2. For drinking water sources,USEPA and DHS recommend that the 500 series methods for volatile organics be used in preference to the 8000-wastewater series methods due to lower detection limits and superior laboratory QA/QC. The 500 series currently comparable to Method 8260B is Method 524.2. 3. Appropriate analyses are to be used for detection of leaking tank contents. For example,there may be multiple fuels dispensed from the individual tank over its active life. Regulators must determine if the UST was used for multiple fuels, and require the appropriate analyses. 4. Total Petroleum Hydrocarbons as gasoline(TPHg)and diesel(TPHd)ranges(volatile and extractible, respectively)are to be analyzed and characterized by GC/FID with a fused capillary column and prepared by EPA method 5030(purge and trap)for volatile hydrocarbons, or extracted by sonication using Method 3550 for extractible hydrocarbons. Fused capillary columns are preferred to packed columns; a packed column may be used as a"first cut"with"dirty" samples or once the hydrocarbons have been characterized and proper QA/QC is followed. 5. Silica gel cleanup of TPHg and TPHd samples to remove weathered hydrocarbons or breakdown products is not acceptable, as these compounds removed may contribute to impairment of beneficial uses of water through adverse taste and odor and/or toxicity. If natural background compounds are suspected to be contributing to high TPH concentrations that are not associated with the petroleum hydrocarbon release, comparison with samples from background locations, out of the influence of the petroleum hydrocarbon release may be used to justify adjusting TPH concentrations. 6. Tetraethyl lead analysis may be requested if the total lead concentration exceeds the naturally occurring(or background)concentration for lead. 7. Oil and Grease(O &G) analysis may be requested when heavy, straight chain hydrocarbons are present. As of 1 January 2002,US EPA requires O&G analysis by EPA Method 1664A. 8. Practical Quantitation Limits(PQLs), also called Reporting Limit by many laboratories, are influenced by analytical method selection,matrix problems and laboratory QA/QC procedures. The PQLs shall be equal to or lower than the detection limits (DLRs) for purposes of reporting published by DHS (http://www.dhs.ca.gov/ps/dsdwem/chemicals/DLR/dlrindex.htm). 9. PQL chain-of-custody and the signed laboratory data sheets are to be submitted containing the laboratory's assessment of the condition of the samples on receipt including temperature, suitable container type,air bubbles present/absent in VOA bottles,proper preservation, appropriate holding time, etc. The sheets must also include the dates sampled, submitted,prepared for analysis, and analyzed.