1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 3
Analysis
The Analysis phase links the Problem Formulation to the Risk Characterization and consists
of the technical evaluation of chemical and ecological data to determine potential for
ecological exposure and adverse effects. The assessment endpoints and ecological
conceptual site model defined in the Problem Formulation focus the Analysis, which
consists of two components - the Exposure Characterization and the Ecological Effects
Characterization. These two components are used to evaluate the relationships between
receptors, potential exposures, and potential effects. The results of these evaluations provide
the information necessary to determine or predict the potential risks to ecological receptors
from the identified stressors under defined exposure conditions. The products of the
Analysis consist of exposure profiles (from the Exposure Characterization) and stressorresponse
profiles (from the Ecological Effects Characterization) that summarize the
relationships between stressors and responses.
3.1 Exposure Characterization
The Exposure Characterization includes an overview of the field activities conducted as
part of the ERA Sampling and Analyses (CH2M HILL, 1998a) and Focused Sampling and
Analyses (CH2M HILL, 2000); an evaluation of the chemical data for sediment/soil, surface
water, pore water, and biota collected as part of the sampling and analysis, an evaluation
of onsite background conditions for inorganic chemicals, an exposure analysis for the
representative species, and the exposure profile.
3.1.1 Field Sampling and Analysis
The first phase of sampling and analysis (ERA Sampling and Analyses) was designed
to complete the initial sampling for areas away from known or suspected sources of
contamination, to conduct toxicity and bioaccumulation bioassays (using site-collected
sediment or water from “random” and “focused” sites), and to analyze field-collected biota.
The sampled areas include material within the dredging “footprint” for the Full Tidal habitat,
but only that portion just below the depth of dredging. The bioassays for the ERA were
designed to determine acceptable levels of inorganic and organic chemicals in media to which
ecological receptors may be exposed under current or future conditions. Bioassay media
included sediment, surface water, and pore water from random and focused sampling sites.
The second phase of sampling and analysis (Focused Sampling and Analyses) was designed
to evaluate the nature of contamination, if any, associated with previously identified known
or suspected sources (such as sumps, wells, pipelines, maintenance areas, etc.), and to
conduct follow-up sampling of randomly sampled locations where composited samples
contained elevated levels of chemicals. This focused sampling was conducted after the
Scoping Assessment Report and EEC Report were completed.
SAC/143368(003.DOC) 3-1 ERA REPORT
7/31/02