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Vicki, please read Leticia's'*�_ sponse and comment whether thef'l are other chromatograms to compare for motor oil. Jim >>> Leticia Valadez 2/24/2006 9:10 AM >>> Hi Jim, I reviewed the attached chromatograms. . .the motor oil standard chromatogram is of analysis in April, while the comparison standard of diesel and sample overlay is in November. It is hard to really compare chromatograms since these chromatograms are presented at different response scales, and with such a large time frame between analyses. Also, it appears a different data acquisition method was used for the motor oil standard (GC1IAT.M) vs. GC11AT1.M for sample, continuing calibration standard, method blank, and instrument blank. I suggest comparing chromatograms using the same acquisition method, and analysis of motor oil within an appropriate time frame at the same response resolution. Thanks, Leticia Leticia E. Valadez Staff Chemist CA Regional Water Quality Control Board 11020 Sun Center Drive #200 Rancho Cordova, CA 95670-6114 Phone: 916-464-4634 E-Mail: lvaladez@waterboards.ca.gov >>> Jim Barton 2/22/2006 2 :37 PM >>> James L.L. Barton, P.G. Engineering Geologist California Regional Water Quality Control Board Central Valley Region, 11020 Sun Center Drive, Suite 200, Rancho Cordova, CA 95670 office (916) 464-4615 fax (916) 464-4704 >>> "Vicki McCartney [EH] 11 <vmccartney@sjcehd.com> 2/16/2006 3 :31:54 PM >>> Jim, I am forwarding a chromatogram for a groundwater sample collected from monitoring well MW- 1 at the Jimco Truck Plaza site in Ripon, California, along with chromatograms I requested from McCampbell Analytical, Inc. for the instrument method blank, motor oil standard, overlay of the sample with the diesel standard, and an instrument blank. The first attachment is the chromatogram for the sample (file 11170513.D) analyzed on November 17, 2005, at 5:16 pm. The second chromatogram is for the method blank associated with this sample (file 11150521.D) analyzed on November 16, 2005 at 12 :14 am. As you can see, this method blank was analyzed 41 hours prior to analyzing the sample. The third chromatogram is for motor oil. I believe this chromatogram is taken from running a curve on this instrument on April 26, 2005 (seven months prior to analyzing this sample) . The fourth attachment shows the sample chromatogram overlaid by the diesel continuing calibration standard chromatogram (file 11170501.D) . It appears to me that the sample fingerprint matches the diesel fingerprint quite well. The last attachment is an instrument blank (file 11170505.D analyzed eight positions prior to analyzing the sample. The consulting firm would like to stop analyzing groundwater samples collected from MW-1 for motor oil since the sample chromatogram appears to match the diesel standard. My concern is that I do not have a current motor oil standard chromatogram to compare with the sample chromatogram. The laboratory spokesperson stated in a different e-mail that the GC-FID instrument is very stable as verified by the diesel CCV and no major maintenance has been performed on the instrument since April 2005. This statement was in response to my concern about whether the column had been cut or any maintenance done on the instrument that would cause a retention time shift. Should I accept that there is no motor oil found in the groundwater sample without comparing the sample chromatogram to a current motor oil chromatogram? Please present this question to your chemist. Unrelated to the above, I need guidance when requesting that a responsible party assess the threat of vapor intuition in a building. Exactly what must be done to evaluate this 2