Sediment Management Strategy for Restoration of the Cedar and Ortega Rivers
Chandy John, Ph.D., EA Engineering, Science, and Technology, Inc., PBC; 225 Schilling Circle, Hunt Valley,
MD 21031 – Work (410) 584-7000 – cjohn@eaest.com (Primary Corresponding Author)
John C. Higman and Mike Cullum, P.E.; St. Johns River Water Management District, Palatka, Florida.
Contaminants have accumulated in the sediments of the Cedar and Ortega rivers, in North Florida, that
drain into the Lower St. John’s River main stem near the city of Jacksonville metropolitan area. The
St. Johns River Water Management District (District) had initiated projects to “Assess Fine Sediment
Deposition, Erosion, and Transport Rates, and Evaluate Dredge Scenarios” and “Source Identification,
Control Alternatives, Design, and Construct Treatment Systems for Removal of Contaminants.” These
projects were initiated to develop an understanding of where and why contaminants accumulate, which
is essential for making informed management decisions about uses of these rivers and for developing
sound strategies for monitoring environmental changes. The environmental health of the Cedar and
Ortega rivers is of public concern. The Cedar and Ortega rivers are used for transportation, fishing, and
recreation and are an important habitat for endangered marine animals. Elimination of the
contaminant discharges to these rivers and pollution source control that is planned through
implementation of these projects will significantly reduce contaminant loads to these rivers.
Many contaminants introduced into these rivers are associated with sediment particles. After repeated
cycles of transport, deposition, re-suspension, and biological and chemical interactions, the
contaminants on particles eventually may be buried in bottom sediments. Previous District-sponsored
studies had identified the Cedar and Ortega rivers, to be heavily contaminated with polychlorinated
biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), heavy metals (e.g., mercury and cadmium),
and pesticides. The Cedar River flows through an industrial zone within the city of Jacksonville, and is
believed to be a greater source of these contaminants than the Ortega River. A significant source of the
PCBs is believed to be an industrial source in the proximity of Cedar River. The PAHs are derived from
various point and non-point sources ultimately associated with petroleum hydrocarbons. Both PCBs and
PAHs have high particle affinity, and their rates of biogeochemical degradation are low. Heavy metals
show a similar affinity. These fine sediment-bound contaminants are transferred to fish and shellfish at
levels that may pose a threat to these organisms. Watershed studies in the Cedar and Ortega rivers
have found that the sediments are contaminated with PCBs and PAHs. Earlier analysis of sediment core
samples showed that average PCBs, PAHs, mercury, and lead concentrations in the Cedar and Ortega
rivers in a large percentage of the measured sample concentrations exceeded the U.S. Environmental
Protection Agency’s threshold effect levels for aquatic biota. This presentation will discuss some of the
results of these studies and potential remedial options.