1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 5
Summary, Conclusions, and Recommendations
This section presents the summary, conclusions, and recommendations of the ERA for the
Bolsa Chica Lowlands. The objectives of the Bolsa Chica Lowlands project ERA consisted
of adequately characterizing of contamination in the Lowlands, providing
bioassay/bioaccumulation data necessary to assess ecological risks and to determine cleanup
criteria, to assess potential and actual risks to ecological receptors using the Lowlands,
and to aid in the design of wetland restoration. The ERA provides a format to achieve these
objectives and uses all of the available site information to evaluate potential effects to aquatic,
semi-aquatic, and terrestrial receptors under current and expected future conditions.
5.1 Summary
The ERA was conducted using a phased/tiered approach that was consistent with
established methodologies, but had been adapted to the specific needs of the Bolsa Chica
project. Phase I included an initial review of available data and resulted in the CSP/ERA
Work Plan (CH2M HILL, 1998a), and Scoping Assessment (CH2M HILL, 1998b). Phase II
consisted of the ERA Sampling and Analyses whereby additional site-specific data were
collected and evaluated resulting in the EEC Report (CH2M HILL, 1999 ) and Revised Work
Plan (CH2M HILL, 2000). Phase III consisted of the Focused Sampling and Analyses, during
which additional site-specific data were collected and evaluated to fill remaining data gaps,
and completion of this baseline ERA.
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/Kinnetic
Laboratories during the ERA Sampling and Analyses and the Focused Sampling and Analyses.
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) and the data set was of high quality.
The ERA Sampling and Analyses project component was designed to complete sampling for
areas away from known or suspected sources of contamination (random sampling
locations), to conduct toxicity bioassays and bioaccumulation studies using site-collected
sediment and water from both random and focused sampling areas, and to analyze fieldcollected
biota for chemicals that bioaccumulate. Random sampling was conducted in areas
away from known or suspected contamination, while focused sampling was conducted at
selected areas with known contamination.
The Focused Sampling and Analysis phase of the ERA occurred in 2000 to conduct more
detailed analyses of previously sampled “random” locations (sampled as part of the ERA
Sampling), and to identify the nature of contamination associated with previously identified
sources (such as sumps, wells, pipelines, maintenance areas, etc.) and potential sources. The
focused sampling locations were divided into three main categories: (1) Random Follow-up
sites, (2) Previously Uncharacterized sites (Cleanup Agreement and Release [CAR] sites),
and (3) Partially Characterized sites.
SAC/143368(005.DOC) 5-1 ERA REPORT
7/31/02