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Publisher Summary The evaluation of the nature and extent of heavy metal contamination in the environment and the need for remediation has become one of the most perplexing environmental challenges for mankind in recent years. This chapter describes a case study in which bioassays were used in conjunction with soil data to determine the areas of contamination and the need for remediation. A Remedial Investigation was undertaken by the U.S. Department of the Navy at the Naval Weapons Station, Concord, California, under the Navy Installation Restoration (IR) Program to meet the requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act (SARA). Contamination resulted from the uncontrolled discharges of industrial waste into environments adjacent to chemical manufacturing plants. Chemical contamination was thought to have migrated from the sources either down a creek into wetlands or down drainage ditches in the wetlands into tidal creeks that ultimately emptied into Suisun Bay. The extent of the migration was not known in 1984, when this investigation was initiated. Soil samples had shown elevated levels of arsenic, cadmium, copper, lead, zinc, and selenium in certain locations in the field.

Publisher Summary This chapter emphasizes the contaminant mobility of heavy metals using data collected between 1983 and 1989. The placement of Black Rock Harbor sediment in an upland disposal environment resulted in pronounced changes in some attributes of the contaminated sediment. Following upland disposal, the dredged material dried and oxidized. The pH of the dredged material dropped from 7.6 in 1983 to 3.2 by the end of a joint Corps of Engineers (CE)/Environmental Protection Agency Field Verification Program (FVP) in 1986. This substantial decrease in dredged material pH was presumably a result of the decomposition of organic matter, the oxidation of sulfide, limited pH buffering capacity in Black Rock Harbor sediment, low percent CaCO 3 equivalent, and the acid rainfall of pH 4.0–4.5 at the field site location. The upland animal bioassay predicted that earthworms would not survive in the dredged material under oxidized conditions. Through 1986, earthworms could not survive on the dredged material. Currently, control plots devoid of vegetation contain few animals. In particular, no soft bodied animals were observed or collected from this environment.