1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 3: ANALYSIS
sampling program is included in Table A-1. Biota (terrestrial plants, terrestrial and aquatic
invertebrates, fish, black-necked stilt eggs, and small mammals) were collected at various
locations within the Lowlands (as shown in Figure 3-1).
Focused sampling was conducted to characterize and determine the extent of contamination
of selected known or suspected sites where previous industrial activity took place and to
measure chemicals present in surface water inflows to the Lowlands. In the ERA Sampling
and Analyses phase of the project, sediment samples were taken within the selected sites to
provide media for bioassays and to determine concentrations of contaminants at various
depths; they were analyzed for Suites A, B, or C. Surface water inflow areas were sampled
for pH, conductivity, metals, organochlorine herbicides, and organophosphorus insecticides
during low-flow and storm events.
Table A-2 in Appendix A summarizes the chemical analyses of surface sediments collected
during the field sampling (Suite C), sediments or water tested for toxicity/bioaccumulation
(Suite C or D), and sediment/soil collected from deeper depths within the same sample
cores (Suites A and B). In addition, plant and animal tissues were analyzed for those
chemicals that were likely to bioaccumulate, including metals, organochlorine insecticides,
polychlorinated biphenyls (PCBs) and polycyclic aromatic hyrocarbons (PAHs) (Suite E).
Bird eggs were analyzed using a modified Suite E, which includes all Suite E compounds
except PAHs. Tissue samples resulting from the laboratory bioaccumulation exposures were
also analyzed for contaminants (Suite E).
3.1.1.2 Focused Sampling and Analyses
The purpose of the focused sampling program was to further characterize known or
potential sources of contamination within the Lowlands. The focused sampling sites include
Random Follow-up sites (composite areas sampled during the Random Sampling where at
least one analyte exceeded benchmarks selected by the Technical Committee), CAR sites,
and Partially Characterized sites (previously sampled by Tetra Tech [1996]). The sampling
strategy is discussed in more detail in Appendix A, and the numbers of samples are listed
by facility/feature and analytical suite in Table A-1:
Random Follow-up
Random Follow-up sites are discrete locations sampled during the Random Sampling
program where the composite sample representing those locations had at least one analyte
that exceeded criteria established by the Technical Committee. Calculated LC20 and LC50
values (from the Bolsa Chica ERA), Effects Range-Low (ER-L) and Effects Range-Median
(ER-M) values published by Long et al. (1995), and calculated background levels were used by
the Technical Committee as guidelines in establishing the selection of Random Follow-up sites.
A total of 190 Random Follow-up sites were sampled and are shown in Table A-1 in
Appendix A. Most of the individual random sampling locations were re-sampled to a depth
of 0.5 feet bgs. Boring depths were advanced to the original project depth of 6 feet bgs when
the bottom composite sample exceeded any of the above stated criteria. Selection of analyses
to be performed on the Random Follow-up sites was based on those constituents that
exceeded screening levels set by the Technical Committee on sediment/soil samples at the
intervals where the exceedances occurred at each location. Appendix A provides a complete
listing of analyses performed on the Random Follow-up samples.
SAC/143368(003.DOC) 3-3 ERA REPORT
7/31/02