Prepared by: Michael A. Zarull, John H. Hartig, and Lisa Maynard
Sediment Priority Action Committee
Great Lakes Water Quality Board
VI. CASE STUDIES OF SEDIMENT REMEDIATION AND ASSOCIATED ECOLOGICAL BENEFITS
PCB Contaminated Sediment Remediation in Waukegan Harbor
Waukegan Harbor is situated in Lake County, Illinois on the western shore of Lake Michigan. Constructed by filling a natural inlet and portions of adjacent wetlands, Waukegan Harbor has water depths varying from 4.0 to 6.5 m. The harbor sediment is composed of soft organic silt (muck) which lies over medium, dense, fine-to-coarse sand.
In 1990, approximately 75 commercial ship dockings were present in the harbor. The majority of the materials brought through the harbor were building/construction materials for nearby Chicago industries (Hey and Associates 1993).
Although substantial recreational use occurs in the area around the harbor, land use in the Waukegan Harbor area is primarily industrial. Of the major facilities present, the Outboard Marine Corporation (OMC) was identified as the primary source of PCB contamination in harbor sediment. In 1972, OMC dismantled a coke oven gas plant (previously built and owned by the North Shore Coke and Chemical Company) to construct their own facilities for manufacturing recreational marine products. U.S. EPA investigations in 1976 revealed high levels of PCBs in Waukegan Harbor sediment and in soil close to OMC outfalls. Concurrently, high levels of PCBs (above the U.S. Food and Drug Administration action levels of 2.0 mg/kg PCB) were also found in resident fish species. As a result, in 1981, the U.S. EPA formally recommended that no fish from Waukegan Harbor be consumed. Subsequently, the Lake County Health Department posted signs warning residents that consumption of fish from the northern harbor could be dangerous to human health.
With the discovery of Waukegan Harbor's PCB problem in 1976, the U.S. EPA and Illinois EPA became involved in a lengthy litigation process with OMC, and as a result of the requirements of the 1980 Comprehensive Environmental Response Compensation and Liability Act (Superfund) and its 1986 Amendments, a Consent Decree was entered by the U.S. Justice Department in District Court in 1989. The Consent Decree called for remediation of the contaminated sediment greater than 50 mg/kg PCBs.
Early investigations of harbor sediment indicated that approximately 136,000 kg of PCBs were in the harbor proper (International Joint Commission 1989). In the most highly contaminated areas of the harbor (Slip #3), PCB concentrations in sediment were as high as 500,000 mg/kg (Figure 3). Severely contaminated areas totaled about 19 ha, including the Upper Harbor, Slip #3, and land on the northern edge of OMCs property (International Joint Commission 1987a).
Remedial efforts in the harbor began in 1990, with harbor dredging conducted in 1992. As a result of the Consent Decree, OMC provided approximately $20-25 million for remediation, which included the construction of three containment cells. Approximately 24,500 m3 of PCB contaminated sediment was removed from the harbor using a hydraulic dredge. Approximately 2,000 m3 of PCB contaminated sediment in excess of 500 mg/kg PCBs was removed from Slip #3 (a "hot spot" that accounts for the majority of the PCBs on the site), and thermally extracted onsite to at least 97% (Taciuk Process). Soils in excess of 10,000 mg/kg of PCBs were also excavated
Figure 3. Outboard Marine Corporation site before remedial action (U.S. EPA 1988)
and treated onsite by thermal extraction (Hartig and Zarull 1991). In all, 11,521,400 kg of material were treated, and 132,500 liters of PCBs were extracted and taken offsite for destruction. The treated harbor sediment was placed in the OMC containment cells. The upper harbor sediment that was dredged was placed in the Slip #3 containment cell. Extracted PCBs were transported to an offsite facility for high-temperature combustion (>2200oF) in accordance with the U.S. Toxic Substances Control Act (TSCA). No soils or sediment that exceeded 50 mg/kg PCBs remained onsite, except those within the containment cells.
Following completion of the soil and sediment remediation, the cells were closed and capped with a high density polyurethane liner and a soil cover. Extraction wells in each cell maintain an inward hydraulic gradient, to prevent PCB migration. The cells are operated and maintained by OMC. To offset the loss of slip #3, a new slip (#4) was dredged and opened to the public in July 1991.
OMC was required to comply with the 1989 Consent Decree and all Superfund requirements. In addition, extracted PCBs had to be transported and incinerated in accordance with requirements of the U.S. TSCA. The primary cleanup target was the removal, containment, and treatment of contaminated sediment in and around the OMC property in order to meet the 50 mg/kg PCB limit determined under the consent decree.
Fish contaminant monitoring, conducted after the Superfund remediation dredging in 1992, shows a substantial decrease for PCB concentrations in carp fillets. Figure 4 presents trend data for PCBs in Waukegan Harbor carp fillets (Illinois Environmental Protection Agency undated memo; Illinois Environmental Protection Agency 1996; U.S. Environmental Protection Agency - STORET). PCB levels in 1993 fish suggest that dredging did not cause significant PCB resuspension. Contaminant levels in 1993 fish averaged 5 fold lower than those tested in previous years up through 1991 (Table 3). Contaminant levels from 1993-1995 appeared to remain at these lower levels, but there is a suggestion of an apparent increase for the period 1996-1998. There is no statistically significant difference between the 1983 and 1998 levels of PCBs in carp (based on a two sample t-test using the data in Table 3).
As a result of the dramatic decline of PCBs in several fish species between the late 1970s and 1990s, the posted Waukegan Harbor fish advisories were removed, although fish advisories still exist for carp and other fish throughout Lake Michigan. The Illinois Lake Michigan Lakewide Advisory is protective of human health, as PCB concentrations in Waukegan Harbor fish are considered similar to those found elsewhere in Lake Michigan.
Approximately 136,000 kg of PCBs were removed from the sediment through this Superfund action. Sediment sampling indicates that about 900 kg of PCB contaminated sediment remains in the navigational channel of the harbor. This PCB contamination and silting has resulted in cargo carrier restrictions on ships passing into the channel. The Department of Transportation has observed disturbance of navigational sediment by prop wash. The U.S. Army Corps of Engineers, working with the Waukegan Port District, is in the second phase of a study to dredge the remaining contaminated sediment from Waukegan Harbor. The proposed project has three objectives: to remove the remaining contaminated material that lies outside of the Federal navigational channel (an estimated 23,000 m3); to deepen the inner and outer harbor to a proposed 7-8.2 m and 7.6-8.8 m depth, respectively; and to complete maintenance dredging (207,000 m3) of the Federal navigational channel (the Superfund cleanup occurred in the uppermost portion of the inner harbor, which lies outside of the Federal navigational channel; the navigational channel itself hasn't been dredged since the early 1970s). The total amount of sediment to be dredged in this project is 230,000 m3, at a total estimated cost of $12-14 million. Work could possibly begin in 2002, with the first year involving construction of a Confined Disposal Facility and the second year consisting of dredging.
Figure 4. Average PCB levels, with 95% confidence intervals, in Waukegan Harbor carp fillets
(1991 and 1994 - one sample only; 1992 - dredging occurred, no sampling)
Table 3. Qualitative comparison of PCB levels in Waukegan Harbor fish
|Description of Sample||Reference or Source|
|white sucker||3.6||whole||U.S. EPA|
|white sucker||26.8||whole||U.S. EPA|
|white sucker||1.06||whole||Illinois EPA|
|white sucker||0.62||whole||Illinois EPA|
|white sucker||0.10||whole||Illinois EPA|
|white sucker||0.01||whole||Illinois EPA|
|white sucker||1.17||whole||Illinois EPA|
|white sucker||0.26||whole||Illinois EPA|
|white sucker||0.37||whole||Illinois EPA|
|white sucker||0.52||whole||Illinois EPA|
|white sucker||0.17||fillet||Illinois EPA|
|white sucker||0.36||fillet||Illinois EPA|
|white sucker||0.86||whole||Illinois EPA|
|white sucker||0.77||whole||Illinois EPA|
|white sucker||0.90||whole||Illinois EPA|
|white sucker||0.30||whole||Illinois EPA|
PAH Contaminated Sediment Remediation in the Main Stem, Black River
The Black River enters the south shore of Lake Erie at Lorain Harbor, in north-central Ohio between Cleveland and Sandusky. This river system drains approximately 1,210 km2 of Lorain, Medina, Ashland, Huron, and Cuyahoga Counties. The geographic limits of the Area of Concern are considered to be the entire river basin.
The Black River drainage basin is dominated by agricultural and rural land uses (89%). Residential, commercial, and recreational uses make up the remaining 11%, and are concentrated in the lower regions of the river. Although USS/KOBE Steel Company is the primary industry in the lower river (between river kilometer 8.7 and 3.3), several other major facilities are located further upstream.
The Area of Concern has 45 National Pollutant Discharge Elimination System (NPDES) permitted dischargers - 26 industrial and 19 municipal. Of the industrial dischargers, the only one that is considered to be "major" (discharging >1 million gallons/day) by the U.S. EPA is USS/KOBE Steel. Until 1982, USS operated a coking facility, which is considered to have been the major source of PAH and metal contamination within the area.
A 1985 Consent Decree (U.S. District Court - Northern District of Ohio 1985) mandated USS/KOBE Steel Company to remove 38,000 m3 of PAH contaminated sediment from the mainstem of the Black River. The goal of the sediment remediation project was to remove PAH contaminated sediment in order to eliminate liver tumors in resident brown bullhead populations.
Tests from 1980 confirmed the presence of elevated levels of cadmium, copper, lead, zinc, cyanide, phenols, PAHs, oils, and grease in sediment adjacent to the former USS steel coke plant outfall. PAH concentrations in this area totaled 1,096 mg/kg (Baumann et al. 1982). Tests also confirmed the presence of low levels of pesticides (DDT and its metabolites) in both the mainstem and the harbor regions (Black River Remedial Action Plan Coordinating Committee 1994). This sediment exceeded U.S. EPA's Heavily Polluted Classification for Great Lakes harbor sediment. As a result, all mainstem and harbor sediment dredged during U.S. Army Corps of Engineers maintenance operations required disposal in a confined disposal facility.
High sediment PAH levels corresponded to a high frequency of liver tumors in resident populations of brown bullheads (Black River RAP Coordinating Committee 1994). Although sediment PAH levels had declined since the USS's coking facility was shut down, levels were still of concern.
Sediment remediation occurred upstream of the federal navigational channel in the vicinity of the coke plant outfall. Dredging of the sediment began in 1989. The operation utilized a closed, watertight, clamshell dredge to reduce the loss of sediment to the water column. To prevent the spread of oil, an oil boom was erected. The sediment was moved from a dredge barge to a containment cell on the USS/KOBE site using specially designed vehicles. Although the sediment was not considered hazardous waste, the disposal site had special design requirements to clean all hazardous waste from the cell, line it, allow for dewatering of the dredged sediment and collection of the decanted water for treatment, capping after the dredged materials were deposited, and post-closure monitoring. Without these conditions, the placement of the dredged sediment in the cell would have exacerbated existing ground water contamination and violated Resource Conservation and Recovery Action (RCRA) requirements for closure. In the event of a spill, a contingency plan was defined and environmental monitoring was conducted prior to, during, and following dredging. A total of 38,000 m3 of sediment were removed during the operation. This action was completed in December 1990.
Under the Consent Decree, USS/KOBE Steel paid $1.5 million for the dredging and containment of the sediment. USS/KOBE Steel was required to comply with the 1985 Consent Decree (U.S. District Court - Northern District of Ohio 1985). The Consent Decree was issued to deal with violations of the Clean Air Act, but included several supplementary environmental requirements, one of which was the dredging of the PAH contaminated sediment. In addition, disposal of dredged sediment had to comply with U.S. RCRA requirements. The dredging project also required permits under the Clean Water Act for NPDES, Section 404 dredge and fill, and a Section 401 water quality certification.
The primary cleanup target was the removal of sediment in the area of the former USS coke plant to "hard bottom", or the underlaying shale bedrock. No quantitative environmental targets or endpoints were established, although post-dredging sampling was required to test for remaining areas of elevated PAH concentrations.
Prior to dredging, PAH concentrations ranged from 8.8-52.0 mg/kg within Black River sediment. As a result of dredging, PAH concentrations in sediment declined (Table 4).
Table 4. PAH concentrations (mg/kg) in Black River sediment in 1980 (during coke plant operations), 1984 (coking facility closed, pre-dredging), and 1992 (post-dredging)
(USS coking facility closed down in 1982, dredging occurred from 1989-1990)
aBaumann et. al. (1982)
bFabacher et. al. (1988)
cBlack River Remedial Action Plan Coordinating Committee (1994)
PAH levels in brown bullheads, which had been monitored since the early 1980s (Baumann et al. 1982; Baumann and Harshbarger 1995), suggest some very interesting relationships between liver neoplasms and the dredging of sediment. Figure 5 illustrates the prevalence of hepatic tissue conditions (cancer, non-cancer neoplasm, altered hepatocytes, normal) found in fish of age 3 in 1982 (during coke plant operations), 1987 (after coke plant closing, prior to dredging), 1992 (exposed to dredging as age 1), 1993 (exposed to dredging as young of year), and 1994 (hatching after dredging was completed).
The incidence of liver cancer in bullheads of age 3 decreased between 1982 and 1987, corresponding with decreased PAH loadings following the coke plant closure in 1982. There is general consensus that the increase in liver cancer found in the 1992 and 1993 surveys is a result of PAH redistribution which occurred during the 1990 dredging efforts. No instance of liver cancer was found in 1994 samples of age 3 brown bullheads. Further, the percent of normal liver tissues increased from 34% to 85% between 1993 and 1994. This elimination of liver tumors and the increase in the percentage of normal tissues in the resident brown bullhead populations as a result of sediment remediation provides substantial evidence of the efficacy of the remedial strategy.
Figure 5. Percentage of age 3 brown bullheads from the Black River having various liver lesions (Baumann and Harshbarger [in press])
Existing Links Between Contaminated Sediment and Ecological Damage
Establishing quantitatively the ecological significance of sediment-associated contamination in any area is a difficult time- and resource-consuming exercise. It is, however, absolutely essential that it be done. It will likely be used as the justification to force action, and also as the rationale for proposing when intervention is necessary in one place but not another. Bounding the degree of ecological impact (at least semi-quantitatively) provides for realistic expectations for improvement if sediment remediation is pursued. It should also provide essential information on linkages that could be used in other use restoration components in the RAP (e.g., habitat improvements to increase population levels, etc.).
Based on the investigations, a rather straightforward ranking of sites should be possible. At best, a ranking among Areas of Concern, but at worst, a ranking of sites within an individual Area of Concern. However, in order to do this, and thereby establish a priority for action, the investigation should also provide information of a temporal nature (that is, how stable are the observed relationships with time, what are the key controlling factors, and what temporal scales are they expressed or affected on?). This information is critical, whether a non-intervention or an intervention option for remediation is chosen. In the former case, while the sediment-associated contaminant may not be responsible for any significant ecological damage, conditions may change in the future (e.g., sewage loads increase, leading to increased oxygen demand in the water and sediment, leading to changes in the redox conditions at the sediment-water interface, leading to increased bioavailability of a metal, leading to toxic effects, leading to population shifts in the benthos, and so on). In the latter case, attention may be focused on one specific contaminant or condition, while others are ignored because they are of little or no immediate significance. When conditions are changed because of a cleanup, surprise and disappointment may result (e.g., anoxic bottom waters resulting from high organic sediment oxygen demand are removed, invertebrate and demersal fish species once absent due to anoxia now inhabit the area and are exposed to low-level concentrations of a persistent organic compound that biomagnifies, leading to reproductive problems in fish-eating birds). In establishing the present and potential linkages among sediment-associated contaminants and the biota, some information regarding physical stability is essential to complete the temporal picture. Knowledge of susceptibility to resuspension and dispersion of contaminant deposits may affect their priority ranking for cleanup.
Some selected examples of Areas of Concern in the Great Lakes that have compiled and interpreted some of the critical information necessary to link sediment-associated contaminants and specific ecological damage or impairment are presented here. In some cases, they are only a first step in what needs to eventually be done, and they may not yet be quantitative enough to establish and evaluate all of the relationships and conditions described above; however, the value of the information and the effort that has gone into it should be recognized and shared. These are areas where little or no sediment remediation has taken place; however, some of the difficult groundwork essential for the development and implementation of a sediment remedial action plan has.
The Natural Resource Damage Assessments performed in Green Bay (Lake Michigan) and Saginaw Bay (Lake Huron) are good examples of where this link has been made. In Green Bay, contaminated sediment has been quantitatively linked to both fish consumption advisories and reproductive impairment of the Forster's tern population. In Saginaw Bay, contaminated sediment has been linked to fish consumption advisories and reproductive impairment of the common tern population. The linkage of contaminated sediment to use impairments in Saginaw Bay resulted in a $28 million settlement, $10.9 million of which was allocated for PCB contaminated sediment remediation (Table 2).
The Bay of Quinte, Lake Ontario, is nutrient enriched to the point of impairment. Historical inputs of nutrients, especially phosphorus, resulted in excessive algal growth, nuisance algal blooms, and widespread and excessive growth by aquatic macrophytes. These conditions, in turn, have been responsible for (or partially responsible for) taste and odor problems in the drinking water, reduced oxygen in the bottom waters, shifts in the plankton and fish communities, and navigational and recreational problems. The record of increasing nutrient enrichment has been codified in the sediment of the bay. Ironically, it is the sediment that "...will delay the further recovery of the ecosystem and it does affect our ability to influence the ecosystem and improve water quality" (Bay of Quinte Remedial Action Plan Coordinating Committee and Bay of Quinte Remedial Action Plan Public Advisory Committee 1989). Considerable research and monitoring on the external loadings of nutrients, the internal loading (sediment recycling), and ecological processes has quantified the relative significance of the sediment and provided the Bay of Quinte RAP with the information necessary to plan their remediation of these problems.
Hamilton Harbour, Lake Ontario, is contaminated with nutrients, oxygen demanding substances, metals, and persistent organics. All of these contaminants can be found in the harbour sediment in high concentrations. In an attempt to remediate the sediment-associated problems, the RAP Technical Team developed an approach, which was endorsed by the RAP Stakeholders (Canada Ontario Agreement 1985):
The strategy has three essential components. First, it notes that successful remediation depends on source control, as a first priority. It includes, among sources to be controlled, zones of sediment in which concentrations of contaminants are very high. It specifies the locations of these zones, and recommends active intervention in these locations through a combination of removal and in situ treatment. Second, the strategy includes experimentation with techniques such as capping, which may or may not be appropriate as a remedial measure or a follow-up to remedial measures. Third, the strategy calls for monitoring and research to evaluate progress, and to see whether once the above measures have been taken, a passive approach will yield the desired result over time.
The basis for the active intervention part of this strategy stems from detailed studies of the sediment contaminants and their effects on biota (toxicity testing and benthic invertebrate community structure). The second and third parts of the strategy recognize the importance of research and adaptive management to solving a complex problem.
In a number of Canadian Areas of Concern, such as Collingwood Harbour, Spanish River, Severn Sound, and the St. Lawrence River (Cornwall area), a new sediment assessment technique has been applied. This technique, based on biological guidelines, links contaminated sediment with biological effects, allows these effects to be quantified, and allows intercomparisons and priority setting among Areas of Concern and sites within Areas of Concern. These guidelines incorporate the structure of benthic invertebrate communities by using predictive models that relate physical/chemical habitat to an expected community structure and functional responses such as growth, reproduction, and survival in four toxicity tests (bioassays) with benthic invertebrates, using ten test endpoints. Research has established guidelines that allow determination of the community as unstressed, potentially stressed, stressed, or severely stressed. In addition, sediment can be classified as either non-toxic, potentially toxic, or toxic. To simplify the assessment process, software has been developed that incorporates the complex analyses required by the approach and provides the user with straightforward categories of sediment quality on a site by site basis. Where this technique has been applied, an increased understanding of the role, significance, and mode of expression of contaminated sediment has been acquired. In addition, the technique has consistently demonstrated that the volumes of sediment requiring intervention are significantly smaller than were initially estimated, based on chemical guidelines (Reynoldson and Day 1994; Reynoldson et al. 1995; Reynoldson 1998; Reynoldson and Day 1998).
Future sediment remediation will undoubtedly be contingent upon relating ambient contamination with beneficial use restoration. In particular, it will be essential to establish the relationship between contaminated sediment remediation and ecological improvement or benefit. Accomplishing this requires not only an understanding of the linkages involved, but also a quantification of those relationships. This will not only drive remediation, but also frame expectation.