1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 1: INTRODUCTION
Assessment (1996) into a single ERA chemical database for evaluation of potential risks
to aquatic and terrestrial receptors in the Lowlands.
• Incorporate and update the information from the EEC Report to provide the Problem
Formulation, Exposure Characterization, and Ecological Effects Characterization for this
ERA.
• Present the results of the Risk Characterization, including weight of evidence for
potential risks to aquatic and terrestrial receptors as well as a summary of uncertainties
and/or limitations in the evaluations conducted.
• Present the conclusions and recommendations of the ERA.
1.2 Project Approach
The ERA was conducted using a phased approach as recommended by the U.S. EPA (1992a
and 1998) and California EPA (Cal/EPA 1996a and 1996b). This approach consisted of three
data collection or evaluation phases (Figure 1-3) that were used to produce various
documents, as described below. The data and observations from one phase were used to
determine whether further studies were necessary to meet the objectives of the ERA. This
ensured that “…only the necessary work [was] done and all of the necessary work [was]
done” (U.S. EPA, 1992c). The three data collection phases and associated reports for the
Bolsa Chica Lowlands are:
Phase 1 – Initial review of available data resulting in the CSP/ERA Work Plan (1998a) and
the Scoping Assessment (CH2M HILL, 1998b).
Phase 2 – ERA Sampling and Analyses. Collection and evaluation of additional site-specific
data and preparation of the EEC Report (CH2M HILL, 1999). The Work Plan was then
revised (CH2M HILL, 2000) to describe the next phase of sampling.
Phase 3 – Focused Sampling and Analyses. Additional collection and evaluation of sitespecific
data to fill any remaining data gaps and preparation of this final baseline ERA.
The Work Plan and Scoping Assessment (Phase 1) reviewed and evaluated previously
available data (with the Bolsa Chica Technical Committee) in sufficient detail to identify
chemicals, habitats, and receptors of concern and screen chemical concentrations against
available criteria, standards, or effect levels. The previously available data (Steffeck, et al.,
1996; Tetra Tech, 1996) focused primarily on selected sites within the Lowlands where
known or suspected oil field activities or urban inflow most likely resulted in contaminants
being introduced into the Lowlands environment. Little sampling and few analyses had
been done in most of the Bolsa Chica Lowlands.
The site wide sampling and analyses for the project were implemented in two rounds – the
ERA Sampling and Analyses (first round) and the Focused Sampling and Analyses (second
round). Because of schedule constraints for the project and the level of data review and
evaluation conducted to prepare the Work Plan, the Technical Committee determined that
the first round of sampling sampling could be conducted concurrently with preparation of
the Scoping Assessment (Figure 1-3).
ERA REPORT 1-4 SAC/143368(001.DOC)
7/31/02