1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 3: ANALYSIS
3.1.2 Data Evaluation
The chemical data were evaluated for usability in the ERA (as described in this section) and
evaluated for potential risk to representative receptors based on sample location within
specific evaluation areas. The data for specific Cells were combined into evaluation areas
that either currently have or will have similar habitats after the proposed restoration is
completed. These evaluation areas and the Cells included in each one are as follows:
• Bolsa Bay - Inner Bolsa Bay (Cell IB) and Outer Bolsa Bay (Cell OB)
• Garden Grove - Wintersburg Flood Control Channel - Cell 52
• Full Tidal - Cells 1, 1A, 3 through 8, 15 through 18, 43, 44, 51, 58, 59, 61, and 62
• Future Full Tidal - Cells 14, 19 through 40, and 63
• Muted Tidal plus Rabbit Island - Cells 41, 42, 45 through 50, 53, 55, 60, 66, and 67
• Seasonal Ponds - Cells 2, 9 through 13
• Gas Plant Pond Area - Samples collected downgradient of the former Gas Plant (outside
the numbered Cells, just south of Cells 11 and 12)
• Sitewide (biota only) - terrestrial invertebrates that were composited from throughout
the Lowlands
The analytical data used to characterize exposures consist of the sediment/soil, pore water,
surface water, and biota collected previously by Tetra Tech (1996) and by
CH2M HILL/Kinnetics Laboratories during the ERA Sampling and Analyses and the
Focused Sampling and Analyses. These data were compiled into the ERA chemical database
presented in Appendix D in electronic format (CD).
The electronic data obtained for the Tetra Tech Phase II sampling were checked against the
hardcopy to ensure resolution of the items that had precluded their use in the EEC Report
(CH2M HILL, 1999). These items included missing samples or groups of analytes, lack of
identification for tissue samples, and incompatible structure for inclusion in the electronic
database for the EEC Report. During this review, it was found that all of the items could not
be fully resolved. The electronic database was still deficient in some areas including missing
samples (e.g., diesel and waste oil data were not present for surface water), QA/QC samples
included in the data that were not labeled as such, and lack of locational information (i.e.,
northings and eastings). In addition, the electronic data from Tetra Tech did not include
either a method detection limit or reporting limit for those chemicals that were not detected.
Chemicals that were not detected had either a zero (“0”) or a blank entry for the value. This
results in a slight underestimation of the values calculated in the summary statistics because
one-half the reporting limit was still zero for these chemicals.
The electronic Tetra Tech data were corrected to the extent possible. Data available
electronically from Tetra Tech were incorporated into the ERA chemical database. Tetra
Tech data were also not subjected to any addition data validation processes because this was
reported to have been completed by Tetra Tech when conducting the Phase II
Environmental Assessment (Tetra Tech, 1996).
ERA REPORT 3-6 SAC/143368(003.DOC)
7/31/02