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Page 2 of 4 <br /> I believe EPA Method is 8260 using liquid-based standards is perfectly fine for the BTEX and fuel <br /> oxygenate compounds at our site. <br /> I spoke to the TEG Soil Gas lab in Sacramento (lab contracted to do soil gas analysis for the site) and H&P <br /> Mobile Geochemistry lab in San Diego and they indicate that most labs in California are not doing the <br /> vapor-phase validation check because the difference in value is not significant for BTEX and oxygenate <br /> compounds. In addition,the cost of a single standard is $75 and assuming 70 VOCs on the list, the cost of <br /> one validation check will be approximately $6,000. Add to that the cost of using a second standard to <br /> check the first standard as stated in the 2010 DTSC advisory and we end up with a cost of$12,000 for <br /> doing the vapor-phase validation check for this project. It will be hard to justify the high cost to the client <br /> and the UST Cleanup Fund because the improvement to data quality is insignificant. <br /> As I was reading the 2010 Advisory I noticed that there is an inconsistency in percent recovery during <br /> validation of calibration curve. On page 73, it says the percent recovery should be less than 20% and on <br /> page 74 it says it can be upto 30%. I bought this to the lab's attention and they said this is one of the many <br /> inconsistencies in the procedures described in Appendix F. I believe this is one of the bigger issues that <br /> DTSC and labs are trying to work out and a better and accurate validation procedure will be described in <br /> the final advisory. <br /> Your second request related to ensuring the reporting limits are below the ESLs or CHHSLs for residential <br /> land use. Our lab is able to meet this requirement. <br /> In conclusion, we believe that soil gas sample analysis by EPA Method 8260 using liquid-based standards <br /> is perfectly ok for the BTEX and fuel oxygenate target compounds at the site and it will meet the data <br /> quality objectives for the proposed risk assessment. Also,the reporting limits for EPA Method 8260 will be <br /> below the ESLs or CHHSLs. <br /> Understanding that the DTSC advisory is only a guidance not a regulation, we sincerely request that you <br /> consider the site background, our data quality objectives, target compounds, and re-evaluate the <br /> soil gas your request for vaor-phase validation <br /> the traditionalEPA Method 8260 using rwith analyzing <br /> ng l quid based standards.proceedd let us know if we can <br /> Regards, <br /> Dinesh Rao <br /> Senior Project Manager <br /> Ami Adini &Associates, Inc. <br /> 4130 Cahuenga Blvd, Suite 113 <br /> Los Angeles, California 91602 <br /> Tel (714) 538 0226 <br /> Fax(818)824-8112 <br /> dinesh amiadini.com <br /> From: Vicki McCartney [EH] [mailto:vmccartney@sjcehd.com] <br /> Sent: Friday, January 28, 20113:18 PM <br /> To: Larry <br /> Cc: Dinesh Rao; Yarone (Ron) Madnick <br /> Subject: RE: Work Plan for Soil Gas Collection <br /> Larry, Dinesh, and Yarone: <br /> I have read the draft Advisory-Active Soil Gas Investigation, and agree to AA&A's amended work plan that <br /> includes the collection of one duplicate soil gas sample in a 250 milliliter Summa canister and the analysis <br /> of the soil gas sample by EPA Method 8260 in an off-site State-certified Environmental laboratory. <br /> 2/3/2011 <br />