remediation of pcb-contaminated sediments: volatility and solubility considerations

Remediation of PCB-Contaminated Sediments: Volatility and Solubility Considerations

Ronald J. Scvudato Jeffvey R. Chiarenzelli JuwesJ Pa~ano Michele Wundevlich

The authors are aflliated with the Environmental Research Center (ERC) of the State University of New York, Oswego. R Scrudato received his Ph.D. in geology from the University of North Carolina, Chapel Hill In 1977, he became director of the ERG and has been involved with inactive hazardous waste site remediation and remedial technology development for more than 20 years. He has been a member of the New York State Superfund Management Board since 1986 and is on the Board of Directors of the New York Sea Grant Institute. Jeffrey Chiarenzelli is a geologist and has been aflliated with the Environmental Research Center for aboutfive years. He has been responsible for directing the ERC's advanced oxidative technology and PCB volatilization research programs. James Pagano is a biologist and has directed the ERC's PCB biodegradation research program He is also responsible for the development and maintenance of the ERGS congener-speczQk PCB analytical program, including quality control and assurance. Michele Wunderlich has a background in environmental sciences and has been affiliated with the ERC as a research assistant since 1994. She has worked on the advanced oxidative technology development as well as with the ongoing outreach program involving the National Institute of Environ- mental Health SciencesAJSEPA Superfund Basic Research program focused on the Mohawk Nation PCB project at Akwesasne.

Through volatilization and long distance atmospheric transport, polychlorinated biphenyls (PCBs) have been redistributed throughout the global environment. Over the last 70 years, these compounds havepermeated eve y known environmental niche including the remotepolar regions of theglobe. In this article, thesolubility and volatility of the PCB congeners are reviewed relative to the remedial technologies that are currently in use or under consideration. 7he following discussion focuses primarily on the management options for PCB-contaminated, subaqueous solids that require removal, dewatering, dying, and other treatment to degrade the target contaminants and/or containment in engineered facilities including constructed islands, upland secure landfills and subaqueouspits. Environmen- tal mobility resulting from natural and engineeredprocesses is discussed in relation to thepotential for contributing to theglobal loading and redistribution of PCBs. Additionally, select emerging technologies and management options are reviewed relative to theirpotential toproduce seconda y environmental impacts resulting from the soluble and/or volatile redistribution of PCBs. Based on a lack of long-term experience and the recognition that Contaminants will remain unaltered for decades, technologies involving engineered containment structures should be considered ternporav remedial measures until cost-competitive, destructiveprocessing of contaminated sediments is feasible. 0 1999 John Wiley G Sons, Inc.

INTRODUCTION Polychlorinated biphenyls (PCBs) are a family of semivolatile, organic

chemicals that exhibit properties that made them highly desirable for use in a wide range of industrial applications. This class of compounds was extensively used in processes that required low water solubility, low vapor pressure, inflammability, high heat capacity, low electrical conductivity, and favorable dielectric properties. Although accurate data on the total amount of PCBs produced by the Monsanto Industrial Chemicals Co., sole manufacturer in the United States, are not available, it is estimated that more than 1.2 billion pounds were manufactured during the period between 1929 and 1977 (US. EPA, 1976b). These compounds were used in electrical insulating fluids, lubricants requiring tolerance to high

CCC 1051 -5658/99/0902007-15 0 1999 John Wiley & Sons, Inc.

7

RONALD J. SCRUDATO JEFFREY R CHIARENZELLI JAMES J. PAGANO MICHELE WUNDERLICH

I t is estimated that PCB production in the United States accounted for about one-half of the total world production.

pressures and temperatures; to improve heat and fire resistance in transfer and hydraulic fluids; and as a constituent in elastomers, inks, adhesives, paints, lacquers, varnishes, pigments, garment coatings, pesticides, car- bonless copy paper, and waxes (U.S. EPA, 1976a).

In addition to the United States, other known producers of PCBs include the United Kingdom, France, Italy, Germany, Spain, the former Czechoslovakia, and (up to 1972) Japan. It is estimated that PCB production in the United States accounted for about one-half of the total world production. By mid-1971, Monsanto terminated sales of PCBs and polychlorinated terphenyls (PCTs) except for use in closed electrical systems. In 1976 the Toxic Substances Control Act was passed by Congress and the US. production of PCBs was soon halted because of growing concerns over the environmental persistence and the adverse effects attributed to this class of compounds. Although production in the United States ceased in 1977, PCBs continue to be used in a wide range of industrial applications in the United States and abroad. In 1976, the U.S. Environmental Protection Agency (EPA) estimated that of the total amount of PCBs purchased by U.S. industries for the period from 1930 to 1975, about 150 million pounds were distributed in the general environment-contaminating water, air, solids, and biota (U.S. EPA, 1976b).

As can be seen from Exhibit 1, the PCB molecule consists of the biphenyl ring with one to as many as ten chlorines attached at the ortho, meta, or para positions. These compounds have been internationally marketed under a number of trade names including Aroclor (United States), Clophen (Germany), Phenoclor (France), Kanechlor (Japan), Cloresil (Italy) and others. The Aroclors manufactured in the United States by Monsanto included a range of chlorinated compounds with 21 to as much as 70 percent chlorine. Although an Aroclor can theoretically contain as many as 209 individual compounds or congeners, in practice, environmental samples contain far fewer identifiable chromatographic peaks.

PCB SOLUBIL,ITY AND VOLATILITY Each PCB congener has unique physicochemical properties depen-

dent on the number and position of the chlorine substitution on the biphenyl. Although there are exceptions, with increasing chlorination, congeners become less soluble and less volatile and are consequently more environmentally stable and immobile. For example, the water solubility and vapor pressure (25'C) of a PCB compound with 42 percent chlorine, marketed in the United States as Aroclor 1242, is 0.016 mg/l and 5.7 x lo-*, whereas the more chlorinated Aroclor 1260 is 9.5 x lo-* mg/l and 1.3 x respectively (Hutzinger, 1974). In addition to being less soluble, the more chlorinated PCB compounds have the greater affinity for solid particles and are also the most resistant to chemical and reductive biochemical degradation.

PCBs are generally noted for their low water solubility, yet based on the chlorine content of the compound, the solubility ranges from several parts per million to sub part per billion for the more chlorinated

8 REMEDIATION/SPRING 1999

REMEDIATION OF PCB-CONTAMINATED SEDIMENTS: VOLATILITY AND SOLUBILITY CONSIDERATIONS

Exhibit 1. PCB Molecule Illustrating the Dichlorobiphenyl and Chlorine Bonding at the Ortho, Meta, and Para Positions on the Biphenyl

Polychlorinated Biphenyls (PCBs)

d i c hlo ro b p henyl

Meta Ortho Meta

M d a Ortho Meta

compounds (Rue11 et al., 1993). As can be seen from Exhibit 2, the solubility of the range of congeners comprising Aroclors can vary by more than seven orders of magnitude. The solubility of individual PCB compounds varies by orders of magnitude depending on the degree of chlorination. For example, the water solubility of a PCB congener with one chlorine attached to the biphenyl, 2-monoch1orobipheny1, is 5.9 mg/l, whereas the octachlorinated biphenyl solubility is 0.007 mg/l. The discharge of a specific Aroclor to the aquatic environment can therefore result in the selective partitioning of the lower chlorinated congeners to the aqueous phase. Bush et al. (1995) reported that 65 percent of the PCBs contained in upper Hudson River water consisted of three, lower chlorinated congeners. The more chlorinated compounds are more readily sorbed to particulates and therefore become concentrated in the suspended and bottom sediments.

Within water bodies, microbial processes can have a profound effect on the solubility and therefore the availability of PCBs. Anaerobic microbial dechlorination of PCB-contaminated bottom sediments does not degrade compounds with chlorines attached at the 2 or 6 positions (ortho) on the biphenyl. As a consequence, lower chlorinated, orthosubstituted compounds are enriched in the partially degraded sediment. The residual, partially transformed PCB compounds are more soluble and therefore more available to aquatic organisms. Exhibit 3 depicts the microbial reductive dechlorination of PCBs with time. As can be seen from this illustration, about 25 percent of the total PCBs were degraded within about three months. Dechlorination plateaus after about three months and no further degradation was observed during the remaining 110+ week period

REMEDIATION/SPFUNG 1999 9

RONALD J. SCRUDATO JEPFREY R CHIARENZELLI JAMES J. PAGANO MICHELE WUNDERLICH

Exhibit 2. PCB Solubility Relative to Gas Chromatographic Retention Time (Chlorine Content)

I 0c

I

0.01

0.0001

1 E-06

PCB Solubility In H,O (ppm)

Solubility estimates from: Ruell et al. (1 993) - - _ . - - -

Increasing I

1 E-08 0 I 0 20 30 40 50

Retention Time (min.)

(Pagan0 et al., 1995, 1997). Furthermore, florisil traps used to collect the gaseous products from the reactor used in these experiments indicated the lower chlorinated, primarily orthosubstituted, congeners escaped the reactor as volatile PCBs.

Increased solubility considerations also become an availability factor with physicochemical and biochemical degradation processes that result in the production of lower chlorinated intermediate products. For example, hydroxylated PCBs are produced as intermediate products during photocatalysis (Wang et al., in press), and the produced compounds may be more soluble, and therefore more available, than the suite of parent compounds.

Although relatively insoluble in water, PCBs are lipophilic and readily concentrate in fats and oils. The accumulation of PCBs in the fatty tissues of Great Lakes fish was one of the growing environmental concerns that led to the limited use of these compounds to closed systems during the early to mid-1970s and to the eventual ban on its production and wide use in the United States. PCBs persist in Great Lakes fish at levels requiring fish advisories that recommend that children and women of child-bearing age eat no fish and all others limit consumption to one meal each month.

In addition to carcinogenic concerns, there is growing research evidence that the lower chlorinated PCBs may be implicated in a variety of health effects including breast cancer, hormonal disruption, and


REMEDIATION OF PCB- CONTAMINATED SEDIMENTS: VOLATILITY AND SOLUBILITY CONSIDERATIONS

- 4.1 E a a 3 * 9 t i .L

rn . 3.7

'C: 3.5 aJ R

0 I g 3.3

& 3.1 - a L

2.9

2.7 -

2.5

4

Exhibit 3. Anaerobic Dechlorination of PCBs over Time

- -

A A A A A M A A A A A A A A A A A - -

- -

- - 00 0 II

0 0

A ~ A A A A A f 4 2 8 p p : g P p P - -

I I I I I I I I j : I I I I I I / I I / I I I I I : : I : I / I I I 1 I I / I I I I I I I / I I I I / I I I I I I I I

0 S F 4 SF4(sediment) A SF5 A Aroclor 1248 4.3 1

Anaerobic dechlorination of Aroclor 1248-contaminated sediments during a 124-week experiment conducted in a recirculating, upflow reactor maintained at 35°C. Note the relatively rapid reduction in the chlorine per biphenyl concentration during the initial 20 to 25 week period, followed by a plateau that persisted for the remaining 100+ weeks.

neurobehavioral impacts (Arcaro and Gierthy 1997; Carpenter et al., 1997; Seegal et al., 1997). Natural and engineered processes contributing to the increased bioavailability of the lower chlorinated PCB compounds may therefore have significant health implications that to date have been overlooked or disregarded.

The potential and concern for volatile losses, atmospheric transport, and redistribution of PCBs were recognized as early as the mid-1970s (Bidleman and Olney, 1974; Harvey and Steinhauer, 1974; Haque et al., 1974; Fuller et al., 1976). In reports prepared for EPA, vapor phase PCBs were recognized as a major component of the total PCB budget (U.S. EPA, 197613). More than twenty years ago, EPA estimated that as much as 13 percent of the total PCB input to Lake Michigan was from atmospheric fallout. Recent research indicates PCBs and other semi-volatile compounds readily volatilize from contaminated soils and sediments and as much as 75 percent of the total PCBs can be lost as water is evaporated from subaqueous sediments at ambient temperatures (Chiarenzelli et al., 1997a and b, 199813).

Although classified as semivolatile, vapor phase PCBs are recognized as a primary contributor to the total loading of persistent organic pollutants (POPS) that have been globally redistributed to the higher latitudes (Wania and Mackay, 1993, 1996; Wania et al., 1996; Muir et al., 1996). The lower chlorinated compounds are also the more volatile and partition to the

REMEDIATION/SPRING 1999 11

RONALD J. SCRUDATO JEEFFREY R. CHIARENZELLI JAMES J. PAGANO MICHELE WUNDERLICH

higher altitudes where they have been found in Canadian alpine snows and meltwaters (Blais et al., 1998). Vapor phase partitioning of PCBs will also result in the lower chlorinated compounds being atmospherically redistributed while the more chlorinated congeners remain as residuals in the originally contaminated material.

PCBs continue to be released from environmental stores, including soils and contaminated water bodies, as the atmospheric fugacity changes.

PCB REMEDIAL TECHNOLOGIES During the period between 1930 and 1775, an estimated 290

million pounds of PCBs were deposited in landfills and dumps. By 1975, an additional 150 million pounds were released to the environment, providing a source of contamination to the air, water, soil, sediment, and biota (U.S. EPA, 1976b). There are commercially available technologies to manage the highly contaminated PCB oils- including secure landfills, incineration, pyrolytic processing, and other destructive processes. Since 1776 and passage of the Toxic Substances Control Act (TSCA), the United States has imposed strict regulatory guidelines governing the transport, storage, and disposal of highly contaminated PCB substances that carry stiff penalties for violations. Material containing less than 50 mg/kg total PCBs can still be disposed of in landfills. Since the mid-l970s, however, the highly contaminated fluids contained in decommissioned transformers and capacitors are not being released to the environment or disposed of in municipal landfills. PCB oils, fluids, and material containing greater than 50 mg/kg are classified as hazardous wastes and disposal must meet the TSCA regulatory standards. Because they are strictly regu- lated, these substances do not currently pose as significant a problem to the environment as other, less contaminated and more broadly dispersed material. However, there are large global stores of PCB contaminated liquids and solids in the waters, bottoms, and suspended sediments of lakes, harbors, and rivers of the world. Addition- ally, PCBs continue to be released from environmental stores, including soils and contaminated water bodies, as the atmospheric fugacity changes. Although long regarded to be relatively insoluble and nonvolatile, large quantities of PCBs sorbed to particulates and in the vapor phase are present in the world atmosphere.

In aquatic systems that have been impacted by direct and indirect discharges of PCBs, the size and character of the receiving body of water determine whether the majority of the total PCBs will be in the aqueous phase or contained in the suspended and bottom sediments. Whereas the bottom sediments in a water body impacted by PCB discharges may often contain concentrations in the mg/kg level, the associated aqueous phase concentrations will normally be two to three orders of magnitude lower. Nevertheless, depending on the size and concentration of the water body, the aqueous phase mass of PCBs may be greater in large lake and river systems than the amount stored in the suspended bottom sediments. For example, the total estimated amount of PCBs in solution in Lake Michigan in 1976 was 1.0 x lo5 pounds, whereas the total in the bottom sediments was estimated to be 1.7 x lo4 pounds (US. EPA, 1776b).



REMEDIAL PROCESSES Aqueous Phase PCBs

Isolation and degradation of aqueous phase PCBs are readily achievable using a wide range of commercially available and developing technologies including, but not limited to, activated carbon or resin sorption, biofiltration, ultraviolet irradiation, photocatalysis, ozonation, peroxidation, and a range of electrochemical processes. The more chlorinated compounds are more difficult to desorb from associated organic and inorganic solids whereas the lower chlorinated fractions are more difficult to remove from contaminated liquids because of their relative higher solubilities. Technologies designed to degrade the aqueous phase PCBs, including photochemical, electrochemical and other forms of advanced oxidative processes, preferentially degrade the lower chlorinated congeners and may result in a relative increase in the more chlorinated compounds (Chiarenzelli et al., 1996). Advanced oxidative treatment of aqueous phase PCBs can also lead to the production of more mobile products including hydroxylated intermediates that may be more soluble than the original compound (Wang et al., in press). The effectiveness of advanced oxidative technologies to degrade aqueous phase PCBs is also dependent on the physical and chemical characteristics of the contaminated water. Water hardness, for example, directly affects the effectiveness of the process because the radicals will be scavenged by dissolved carbonates.

Although there are a number of technologies that are effective in degrading aqueous phase P C B ~ , remediation of solids andsolidsuspensions presents unique challenges.

CONTAMINATED SOLIDS AND SOLID SUSPENSIONS Although there are a number of technologies that are effective in

degrading aqueous phase PCBs, remediation of solids and solid suspensions presents unique challenges. Tightly sequestered compounds sorbed to particulates; mixing effectiveness; quenching effects of associated suspended or dissolved compounds; and reduced thermal, radiant, and electrical energy transmission achievable in solid suspensions negatively affect treatment efficiencies of PCB-contaminated solids and slurries. The PCBs are more readily degraded when they are physically and/or chemically removed and isolated from solids. Separation technologies to remove and isolate contaminants sorbed to associated solids involve physical, thermal, and chemical partitioning. Low temperature thermal extraction has been commercially used to separate PCBs from soils. In this process, indirect heating of the contaminated solids vaporizes the semivolatile compounds and, with condensation, the PCBs are concentrated in the aqueous phase. Once separated from the solids, the liquids can be isolated or degraded by thermal, biological, or physico-chemical processes.

Soil washing technologies have been used to remove contaminants adsorbed to solids in slurry suspensions. A wide range of ionic and non- ionic surfactants have been used in solid suspensions or slurries to improve desorption of the contaminants from the particulates. Additionally, a range of organic and inorganic solvents, including steam, have also been effectively used to extract PCBs from contaminated solids. Bench scale

REMEDIATION/~PRING 1999 13


In the United States, 200 miles of the Hudson River have been impacted by PCB discharges by the General Electric Corporation facility at Fort Edwards, New York.

steani extraction experiments conducted on PCB-contaminated soils reduced the total concentration of an Aroclor 1260 from 193 to 76 mg/kg at a liquid to solids ratio of 3:l (Chiarenzelli, personal communication, 1998). With the use of steam extraction, the aqueous solubility was exceeded and three separate phases formed including the condensed liquid, the extracted solids, and a yellow grease-like substance. Analysis of the three phases indicated more than 95 percent of the PCBs were contained in the grease-like material. The liquid condensate contained 122 pg/L and the solids retained 39 percent of the original concentration.

CONTAINMENT TECHNOLOGIES Solids containing a concentration of up to several hundred mg/kg of

PCBs represent one of the most challenging, contentious, and politically charged environmental issues involving PCB-contaminated materials. The extensive, worldwide contamination of riverine and harbor sediments contaminated by PCBs and similar semi-volatile compounds and the large potential costs involved with the remediation of these materials has heightened debate amongst regulators, responsible parties, the scientific community, and community members.

In the United States, 200 miles of the Hudson River have been impacted by PCB discharges by the General Electric Corporation facility at Fort Edwards, New York. Millions of cubic yards of contaminated dredge material must be removed from the New York/New Jersey harbor area annually in order to maintain shipping channels. Thousands of cubic yards of PCB-contaminated sediments are planned for removal from the St. Lawrence River contaminated by PCB and polyaromatic hydrocarbon (PAH) discharges by the Alcoa, Reynolds, and General Motors Corpora- tions. Contaminated soils must be excavated and removed from the residential neighborhoods of Pittsfield, Massachusetts, and thousands of cubic yards of highly contaminated sediments will be removed from the New Bedford, Massachusetts Harbor and stored in engineered containment structures.

Long-term storage of PCB-contaminated solids in designed containment facilities does provide a relatively inexpensive remedial option. As long as the system is kept dry and the integrity of the containment structure is maintained, the contaminants should remain isolated from the surround- ing environment. Containment facilities will require continuous monitoring and maintenance for decades, perhaps centuries. Because there are no long-term examples to provide insights to the effectiveness of containment facilities to isolate contaminated solids, in 1975 EPA expressed concerns about the responsibility, liability, and long-term integrity of landfills used for storage of PCBs.

Containment facilities are designed to prevent the infiltration of surface and groundwater to minimize leachate production. The PCBs sampled from contaminated sediments dredged from the Hudson River remained unchanged for more than a decade after being deposited in containment fill sites (Rhee, personal communication, 1998). As long as the contaminated sediments are kept dry, physicochemical and microbial processes



Because of the low solubility and strong partitioning to solids of the more chlorinated congeners, the bottom sediments of water bodies that have received direct PCB discharges serve as vast repositories of the contaminant.

are inhibited and the contaminated sediments will remain unchanged as long as the integrity of the containment facility is intact.

Because of the low solubility and strong partitioning to solids of the more chlorinated congeners, the bottom sediments of water bodies that have received direct PCB discharges serve as vast repositories of the contaminant. These contaminated sediments consist of admixtures of organic and inorganic solids and when dredged from aquatic systems, varying amounts of water must be removed or separated in order to remove or treat the target contaminants, Additionally, much of the PCB-contaminated sediments found in harbors and rivers are also impacted by other organic and inorganic contaminants. Dioxins, a range of trace metals and other organic contaminants including, but not limited to, PAHs also impact the New York/New Jersey Harbor sediments.

Remediation of subaqueous contaminated sediments therefore presents unique problems and challenges. The bottom sediments must be removed without redistributing large quantities of the contaminated material down current. Once the saturated material is removed, it is dewatered and, if the removed material is to be thermally treated, it must be dried.

PCBs in subaqueous environments present other unique challenges and debate continues on whether more environmental damage is done by physically removing the contaminated material from the impacted body of water. The General Electric Corporation has argued for years that natural biodegradation is effectively reducing the total concentration and toxicity of the PCBs in the Hudson River. Reductive dechlorination of Hudson River PCBs is an active phenomena and there is convincing evidence that the total quantity has declined with time. However, research conducted on reductive microbial degradation indicates this process is limited in that a minimum concentration of about 40 mg/kg total PCBs is required in order for the process to be initiated (Sokol et al., 1998). Furthermore, reductive degradation is not able to completely degrade PCBs and produces a host of lower chlorinated compounds that are more readily available within the aquatic environment.

Various technologies have been proposed and assessed to remediate large quantities of contaminated material that will be removed from the world’s waterways. The range of containment technologies includes long- term storage in engineered upland disposal facilities; containment in excavated, subaqueous pits; and creation of fill sites or islands near the source of the contaminated dredge material similar to the Miller-Hart Island (Hamons et al., 1997) used to contain sediments removed from the Chesapeake Bay area near the Baltimore Harbor.

Containment is normally favored over treatment technologies primarily because of the relatively lower costs. Depending on the selected containment option and transportation costs, this management option is relatively inexpensive compared to treatment technologies designed to degrade the contaminant. However, recent studies suggest significant quantities of PCBs volatilize as water evaporates from contaminated solids (Chiarenzelli et al., 1997a, b; 1998a, b). Although these studies were

&MEDIATION/~PRING 1999 15


conducted on small samples at the laboratory scale, there is sufficient evidence to indicate that PCBs and similar semivolatile organic compounds are being globally redistributed atmospherically (Wania and Mackay, 1993, 1996; Muir et al., 1996; Tenenbaum, 1998).

The PCB concentration of the St. Lawrence River sediments used in the series of experiments illustrated in Exhibits 4 and 5 was about 63 mg/kg. Exhibit 4 schematically illustrates the relative volatile losses of a PCB- contaminated sediment in relation to initial moisture content. As can be seen from this exhibit, volatile losses were directly related to the initial moisture content and maximum losses occurred when the sample was completely saturated. Exhibit 5 depicts the relative volatile losses of Aroclors spiked onto quartz sands. Note also that the sediment collected from the St. Lawrence River (StLR) behaved more like Aroclor 1260 even though the original Aroclor consisted of 1248. The St. Lawrence River sediment used in the experiments depicted in Exhibit 5 was subjected to more than 20 years of reductive dechlorination and therefore enriched in the lower chlorinated congeners. The difference in volatility is attributed to the age of the sediment and the tight sequestering of the PCBs to the solids (Hatzinger and Alexander, 1995). It is evident from these data that the lower chlorinated Aroclors more readily volatilize at ambient temperatures and relative humidity. In a series of similar experiments conducted on contaminated St. Lawrence River sediments, the volatile loss of PCBs at

Exhibit 4. Evaporative Loss of PCB-Contaminated Sediments at Various Initial Moisture Contents

0 20 40 60 30 100

Initial Moisture Content (YO)



ambient temperature and relative humidity was found to be directly related to the evaporative loss of water (R2 > 8.998).

The potential for volatile losses of PCBs from drying sediments at ambient temperatures and relative humidity suggests that effective monitoring is required to ensure that volatilization does not contribute to the global burden of atmospheric organic contaminants. Safeguards may be required to prevent volatile losses during the dewatering and drying of contaminated dredge material. This is particularly true for those sediments that have been microbially degraded resulting in the production of lower chlorinated and therefore more soluble and volatile compounds.

One containment technology currently being considered for the New York/New Jersey dredge material is to transport the material from the dredge site first by barge and then by rail to the Pennsylvania coal fields where it will be mixed with cement and then used to fill abandoned mines. Solidification of contaminated dredge material by addition of a cementing agent is also being considered for other containment facilities. Addition of a cementing agent to dredge material can increase the temperature of the mixture and thereby increase the evaporative loss of water, potentially resulting in the volatile losses of semi-volatile compounds. In order to assess the effects of lime additions to PCB-contaminated material, the USEPA sponsored a research project designed to determine whether the compound affected the temperature of the admixture and resulted in the evaporative loss of the PCBs (Constant et al., 1995). Quicklime additions

Exhibit 5. Evaporative Loss of PCB Aroclors Spiked onto Quartz Sand and Sediment Samples Collected from the St. Lawrence River Contaminated by Aroclor 1248

1 6

1 4

h 1 2

1 0 ul 5 Y

N .- - .- Z # s * 6 2

4

2

0

v)

0 5 I 0 15 20 25

Evaporation Time (hours)

Note: The St. Lawrence River (StLR) sediment has been partially degraded by anaerobic bacteria and the relative evaporative loss in comparison to the spiked sands is attributed to the age and sequestering of contaminants to the particulates.


RONAL,D J. SCRUDATO JEFFREY R CHIARENZELLI JAMES J. PAGANO MICHELE WUNDERLICH

There are commercial technologies to destroy highly concentrated PCB oils and wastes including incineration and land burial in engineered containment facilities.

resulted in significant increases in the temperature of the contaminated material and volatilization accounted for the majority of the loss of the PCBs.

SUMMARY There are commercial technologies to destroy highly concentrated PCB

oils and wastes including incineration and land burial in engineered containment facilities. Aqueous phase PCBs can be separated from liquids by sorption and can be effectively degraded using a range of physicochemical processes.

Additionally, chemical, physical, and biological technologies are available to degrade the lower concentrations, normally at pg/l concentrations, associated with contaminated water. The most difficult challenge involves the removal and effective remediation of the millions of cubic yards of PCB-contaminated bottom sediments in the world’s water bodies. It is now recognized that PCBs are subjected to degradation by indigenous anaerobic microbes found in the bottom sediments of contaminated water bodies and that this process is active in most subaqueous environments. Anaerobic microbial degradation, however, cannot totally degrade the PCBs and produces lower chlorinated, orthosubstituted PCBs, enhancing the solubility and availability of the contaminant to aquatic organisms. In order to reduce the exposure of PCBs, it is therefore imperative to remove the source from the impacted water body and either isolate or degrade the contaminant.

Since the early to mid-l970s, it has been recognized by the regulatory agencies and others that the lower chlorinated PCBs are soluble and volatile and that consequently, select compounds will readily partition to the aqueous environment and to the atmosphere. Despite this recognition, remedial technologies that are invariably contributing to the global loading and redistribution of PCBs and other similar, semivolatile compounds are being used and aggressively promoted. The major remedial challenge, therefore, is to develop cost-effective treatment processes to degrade the PCBs associated with the millions of cubic yards of contaminated soils and sediments that need to be removed from the aquatic environment while minimizing volatile losses. Containment alternatives being considered for this class of material include pretreatment involving the mixing of cementing agents with the contaminated solids or vitrification. Stabilized or solidified contaminated solids will require some form of environmental isolation and long-term monitoring and maintenance to ensure the contaminants continue to remain isolated and immobile.

Containment management options are currently favored over processes involving the destruction of contaminants because of the costs required to destroy or effectively isolate and remove the PCBs from the solid particles. Effective containment will not only require continuous maintenance, but will need to be maintained to ensure the engineered system continues to prevent off-site migration as well as guard against water intrusion. Without water, however, the contaminants will remain virtually unchanged for decades, possibly centuries. Although cost-competitive treatment options are not

18 REMEDIATION/~PRING 1999

&MEDIATION OF PCB-CONTAMINATED SEDIMENTS: VOLATILITY AND SOLUBILITY CONSIDERATIONS

It is evident that the global redistribution of PCBs and similar semi-volatile compounds results from the volatile

atmospheric transport of this class of compounds.

~ lossesand

presently available, engineered containment technologies should be considered temporary solutions. Containment facilities will require additional remedial attention at some time in the future and should be designed and constructed with this recognition. Designs of containment structures should incorporate features that will enable effective recovery of the contaminated sediments when advanced, cost-effective degradation technologies become available.

Bench scale research results indicate PCB volatilization is directly correlated with evaporative water losses. Contaminated sediments subjected to periodic wetting and drying, including intertidal fluctuations and periodic flooding, may well be contributing to the volatile loss of PCBs. Dewatering and drying during the dredging and handling of contaminated sediments may be contributing to the overall global loading of PCBs. Technologies that involve low temperature extraction and/or exothermic reactions that elevate the temperature of the sediments to promote the evaporative loss of water result in the volatile loss of PCBs. Aerobic microbial degradation of PCB-contaminated sediments that involve mixing, aeration, and watering may also be contributing to the global redistribution of PCBs.

It is evident that the global redistribution of PCBs and similar semivolatile compounds results from the volatile losses and atmospheric transport of this class of compounds. To reduce continued exposure to the aquatic environment, the sources must be removed and isolated from the impacted water bodies. However, currently employed and proposed remedial technologies that involve dewatering and drying of contaminated sediments may contribute to the loading of PCBs and other semivolatile compounds to the global environment. To ensure against this possibility, effective monitoring programs should be designed and implemented at remediation sites involving dewatering, drying, thermal processing, and chemical and/or microbial degradation of PCB-contaminated sediments.

REFERENCES Arcaro, K.F., & Gierthy, J.F. (1997). Estrogenic responses of human breast cancer cells to combination of hydroxylated PCBs, pesticides and 17b-estradiol. The Toxicologist (Abst. No. 14991, 39, 295.

Ridleman, T.F. & Olney, C.E. (1974). Chlorinated hydrocarbons in the Sargasso Sea atmosphere and surface water. Science, 183, 516-518.

Blais, J.M., Schindler, D.W., Muir, C.G., Kimpe, L.E., Donald, D.B., & Rosenberg, B. (1998). Accumulation of persistent organochlorine compounds in mountains of western Canada. Nature, 395, 585-588.

Bush, B., Simpson, K. Shane, L., & Koblintza, R. (1995). PCB congener analysis of water and Caddisfly larvae (1nsectd:Trichoptera) in the Upper Hudson River by glass capillary chromatography. Bulletin of Environmental Contamination and Toxicology. 34, 96-105.

Carpenter, D.O. (1997). New dimensions in our understanding of the human health effects of environmental pollutants. In Proceedings of the 1996 Pacific Basin Conf. on Hazardous Waste (CONF.-9611157:404-418), Kuala Lumpur, Malaysia.

Chiarenzelli, J.R., Scrudato, R.J., Jensen, K., Maloney, T., Wunderlich, M., Pagano, J., Mr Schneider, J. (1998a). Alteration of Aroclor 1248 in foundry waste by volatilization? Water, Air and Soil Pollution, 104, 112-124.

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RONALD J. SCRUDATO JEFFREY R. CHIARENZELLI JAMES J. PAGAN0 MICHELE WUNDERLICH

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remediation of pcb-contaminated sediments: volatility and solubility considerations

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