1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 3: ANALYSIS
The quality of the data obtained during the ERA Sampling and Analyses and the Focused
Sampling and Analyses consisted of a review of 100 percent of the samples (Appendix C).
The results were qualified as appropriate and validation flags were added. The validation
flags used consisted of the following:
• U – Not detected
• J – Estimated value
• UJ – Estimated detection limit
• R – Rejected
The results of data quality evaluation processes indicated that overall, the project data
quality objectives for precision, accuracy, representativeness, completeness, and
comparability were met (Appendix C). Those instances which required qualifying the data
are summarized below:
Matrix effects were evident for some analytes based on the matrix spike, surrogate, and field
duplicate results. Most of these were for sediments and biota tissue, and were expected due
to the complexity of the sample matrices. Most of the matrix recovery failures were
associated with the presence of high concentrations of chlorides in the samples. The matrix
spike, surrogate, and field duplicate deviations resulted in approximately 1.5 percent of the
results being qualified as estimated detects (“J”) and estimated nondetects (“UJ”).
Method blanks were analyzed at the required frequency of at least 1 for every
20 environmental samples or one per analytical batch. Phthalates were routinely detected
in the method blanks, but they are ubiquitous and are considered common laboratory
contaminants. The levels found did not exceed the ecological screening benchmarks and
as such were considered acceptable. Method blanks for method SW8720 (semi-volatiles)
routinely indicated that phthalate contamination may have affected the sensitivity required
to meet the project objectives.
• There were calibration difficulties with some of the analytes resulting in a few results
being rejected and some being qualified as estimated detects and non-detects. The
rejections were due to failure to meet the minimum instrument response, and involved
one analyte (2,4-dinitrophenol) for the Random Sampling. Overall, the qualifications due
to calibration difficulties involved approximately 3 percent of the results for Random
Sampling and 0.7 percent for Focused Sampling.
• Several results (107 from Random Sampling, 236 from Focused Sampling) for
semivolatiles, toxaphene, diesel, or waste oil were qualified as estimated values due
to holding time violations. All other results met the holding time requirements.
• About 1 percent of positive results for pesticides and PCB congeners for Random
Sampling and 0.8 percent for Focused Sampling were qualified as estimated due to
differences between the primary and confirmation results exceeding the acceptance
criterion. The differences were mostly due to interference from coeluting Aroclor peaks
when at least one Aroclor was present.
• In samples that contained Aroclors, some of the Aroclor peaks coeluted within the
retention time windows for some of the pesticides on both the primary and confirmation
columns. This made the identification of some of the pesticides that were reported
SAC/143368(003.DOC) 3-7 ERA REPORT
7/31/02