Central California Ozone Study (CCOS) - Desert Research Institute

CCOS Field Operations Plan Version 2: 5/31/00
probe. This audit method tests the integrity of the ambient monitoring site’s entire ambient air
sampling system, from the probe inlet to the air monitoring equipment. In this method, a gas
calibrator is used to control the dilution of high concentration gases from compressed gas
cylinders containing CO, NO, SO2, CH4; CO, H2S; CO, CH4, and C6H14. The gas calibrator is
also used as an ozone source. The API 400 ozone analyzer is used as a transfer standard for
auditing the site’s ozone analyzer. A TECO 48 CO analyzer is calibrated at two known ambient
level concentrations, plus zero, and is used to trace the amount of CO present in the diluted
sample. The amount of CO present in the diluted sample is then used to calculate the true
concentrations of the other gases in the compressed gas cylinder at each audit level.
4.5.8 VOC Laboratory Audits
Performance audits will consist of through-the-probe audits using a 25-component
hydrocarbon and 3-component carbonyl standard mixtures. These audits will be conducted by
the ARB QA staff using the same procedures used at PAMS sites.
4.6 Approaches To Problem Resolution And Verification Of Corrections
The goal of the audits is to verify the function of each measurement system with respect
to the DQOs. Given that the performance audits are comparisons between the audit standards
and the individual measurement systems, deviations between the audit standards or audit
standard inputs and the measurement outputs can be the result of a problem with the
measurements, the audit standard, or both. The auditors will make every effort to verify the
audit results on site. It is the auditor’s practice not to leave the site until there is deviation within
tolerance between the auditor and the site operator concerning the audit results. It should be
noted that the agreement between the auditor and site operator may be an agreement to disagree.
If this is the case, it will be necessary to further investigate the problem to achieve resolution.
For the radar profilers, RASS and sodars, the initial comparisons are qualitative and
performed using level 0 validated data. If the indicated deviation exceeds the study DQOs, the
auditor and site operator will review the audit equipment and measurement system setups. It is
anticipated that periods when exceedances occur could be validated to level 1 within one week of
the audit and a final resolution made. This assumes the data validation will not alter the values
collected, it will only determine if they are valid.
For all field monitoring audits, the results of the audits will be reported to the on-site
technician and the monitoring supervisor before leaving the sites. Problems noted will be
discussed and an action plan for resolving them developed. If there is a question about the
validity of the audit standard, it will be the responsibility of the auditor to test and correct, or
replace the standard if necessary. If the problem is verified, its disposition will be documented.
The auditor will follow up on each problem within a week of the audit.
Results from all audits will be compiled into a final report that will be submitted to
CCOS Project Manager by October 1, 2001.
Chapter 4: QUALITY ASSURANCE 4-23