4.4.1 Individual Analysis of Alternative 1, High Temperature Thermal Desorption The following sections assess Alternative 1 against the seven evaluation criteria discussed in Section 4.2, including overall protection of human health and the environment; compliance with ARARs; long-term effectiveness and permanence; reduction of mobility, toxicity, or volume; short-term effectiveness; implementability; and cost. 4.4.1.1 Overall Protection of Human Health and the Environment -- Alternative 1 Alternative 1 would protect human health and the environment in the long-term primarily through treatment of the PCB-contaminated material using HTTD. PCB-contaminated material at each of the sites would be excavated and transported to the CTF, thereby reducing the potential for direct contact with, ingestion of, or inhalation of contaminated materials at the CD sites. The majority of the waste material contaminated with PCBs would be treated using HTTD. The PCBs would be separated from contaminated material through HTTD treatment, thereby reducing the potential for the PCBs to released to the environment. The PCBs would be concentrated in a condensed oil waste stream, thus significantly reducing the volume of contaminated material. The concentrated waste stream, as well as certain PCB articles such as capacitors, would be treated at a permitted, off-site incinerator. Waste material not contaminated with PCBs would be properly disposed of in a permitted off-site facility. The short-term protection of human health and the environment during waste treatment is a primary consideration. Human health and the environment would be protected in the short term by implementing strict engineering controls on emissions from the HTTD unit. 4.4.1.2 Compliance with ARARs -- Alternative 1 Alternative 1 relies on HTTD as the primary treatment technology and on waste excavation, sorting, sizing, transporting, and storing as support technologies. Alternative 1 would meet all federal and state ARARs. Appendix B presents the ARARs and criteria TBC for Alternative 1. The ARARs and criteria TBC for Alternative 1 are briefly discussed below. PCBs HTTD effectively removes PCBs from soil, sediment, and sludge to less than 2 ppm in the treatment residual. However, HTTD creates a concentrated PCB waste stream that would require off-site incineration in a TSCA incinerator. In combination with incineration, HTTD would meet chemical- and action-specific ARARs for the treatment and disposal of PCBs. Treatment residuals containing less than 50 ppm of PCBs may be disposed of in a solid waste landfill with written approval of the State. If the treatment residuals contain less than 1 ppm PCBs, the residual could be used for clean backfill. Air Pollution HTTD units have the potential to emit air pollutants but are equipped with air pollution control equipment. This equipment is essential for the safe operation of HTTD and for collecting volatilized contaminants. When equipped with the appropriate air pollution control equipment, HTTD complies with the CAA and the IAC. Waste Treatment and Disposal Materials not treatable by HTTD, such as transformers, capacitors, PCB-contaminated solid waste, and uncontaminated solid waste, would be sorted, sampled as specified in an approved excavation plan, and packaged and shipped off site for proper disposal in accordance with ARARs. If transformers are found, they should be drained and flushed. Dielectric fluid and liquids containing greater than 500 ppm PCBs should undergo off-site incineration. The drained and flushed transformer carcasses may be disposed of as solid waste along with uncontaminated solid waste from the six sites if they contain less than 50 ppm PCBs. Capacitors would be packaged and transported off site for incineration at a TSCA-permitted incinerator. PCB-contaminated solid waste that cannot be treated to levels equivalent to incineration would be disposed of at a TSCA-compliant landfill or incinerator. PCB-contaminated material that can not be directly loaded for transportation to the commercial facility could be stored at the CTF or ISF in preparation for treatment and disposal in accordance with 40 CFR 761.65. Waste Excavation and Handling ARARs associated with waste excavation and handling would be met by Alternative 1. Fugitive dust and particulates would be controlled using best management practices such as wetting the waste material with water or foam. Surface water runon and runoff at the sites would be controlled during excavation using berms and silt fences and by collecting surface water runon in the excavation area using pumps, vacuum trucks, and storage tanks. All collected surface water would be treated using a carbon adsorption system. As part of site restoration activities, sediments collected by the silt fences or the berms would be containerized and transported to the CTF for treatment. The excavation sites would also be monitored to determine the effectiveness of dust and surface water control systems. Surface Water Decontamination water and storm water runon from the excavation sites should be collected, containerized, treated using carbon adsorption, and discharged to a POTW or surface water body in accordance with pretreatment standards or NPDES limitations of the CWA. Water from the lagoon at the Winston- Thomas Sewage Treatment Plant site could be pumped through carbon adsorption units and discharged to the Dillman Road POTW. Other Requirements Alternative 1 would also comply with other non-ARARs, including OSHA rules governing worker health and safety; INDOT regulations for the packaging, labeling, and shipping of hazardous materials; and the CERCLA Off-Site Rule for proper off-site disposal of CERCLA wastes. All waste material from the six sites handled off site must comply with the CERCLA Off-Site Rule. 4.4.1.3 Long-Term Effectiveness and Permanence -- Alternative 1 The long-term effectiveness of HTTD was assessed in terms of the risk remaining after treatment. Risks may be posed by chemicals not removed from the contaminated material during treatment. Performance data, factors that influence performance, and system limitations are discussed below. High Temperature Thermal Desorption Performance EPA has specified a PCB performance standard of 2 ppm for evaluating whether HTTD systems are equivalent to incinerators in removing PCBs. Full- and pilot-scale applications using a number of HTTD technologies prove that this PCB performance standard can be met. The results of full-scale applications of thermal desorbers at PCB-contaminated sites are discussed below. Table 4-4 summarizes full- and pilot-scale performance data for various HTTD technologies. To date, only three vendors have used thermal desorption technology for full-scale remediation of PCB-contaminated Superfund sites: SoilTech; RUST; and Westinghouse Remediation Services, Inc. (WRS). The SoilTech ATP system was used at the WBD site in Brant, New York, and at the Waukegan Harbor Superfund site in Waukegan, Illinois. At the WBD site, the ATP was used in combination with dechlorination; therefore, the performance of the ATP at the WBD site is discussed in Section 4.4.2.3. Performance data was collected during SITE demonstrations and proof-of-process (POP) tests at the three sites. Approximately 253 tons of soil was treated during the SoilTech ATP SITE demonstration at the Waukegan Harbor Superfund site in June 1992. The average PCB concentration was reduced from 9,761 mg/kg in feed soil to 2.0 mg/kg in treated soil, a 99.8 percent average removal efficiency. An average of 0.84 microgram per dry standard cubic meter (頜/dscm) of PCBs was emitted to the atmosphere from the ATP stack, resulting in a 99.999987 percent DRE. During the Waukegan Harbor site remediation, the ATP treated about 12,800 tons of harbor sediment and sandy soil containing 6,700 to 23,000 mg/kg PCBs. The treated soil PCB concentrations were less than 2 mg/kg. The SoilTech ATP has been used to remediate three additional Superfund sites contaminated with VOCs, SVOCs, and pesticides. The RUST X*TRAX system SITE demonstration was performed in May 1992 at the Re-Solve, Inc., Superfund site in North Dartmouth, Massachusetts. Approximately 215 tons of PCB-contaminated soil was treated. The average PCB concentration in feed soil was 247 mg/kg, and the average PCB concentration in treated soil was 0.13 mg/kg, a 99.95 percent removal efficiency. PCBs were not detected in stack gas samples. During the Re-Solve, Inc., site remediation, the X*TRAXTM system treated over 50,000 tons of soil containing 25 to 13,000 mg/kg PCBs. Treated soil PCB concentrations ranged from 2 to 8 mg/kg. The X*TRAX system has been selected to remediate a PCB-contaminated sludge site in South Carolina. The WRS low temperature thermal stripping (LTTS) system was selected to clean up the Acme Solvents Reclaiming, Inc. (Acme), site in Rockford, Illinois. The site is contaminated with VOCs, phthalates, and PCBs. A POP test was conducted in March and April 1994. Approximately 210 tons of contaminated soil was treated during 10 test runs. Contaminated soil contained up to 20 mg/kg of PCBs, and treated soil contained less than 2.5 mg/kg of PCBs. The vent gas contained less than 1.8 g/dscm of PCBs. During the Acme site remediation, the WRS LTTS treated about 6,000 tons of soil and achieved an average treated soil PCB concentration of 0.6 mg/kg. Limited bench-scale tests on dioxin-contaminated soil indicates that the SoilTech ATP can effectively remove dioxins from soil. Dioxin concentrations were reduced from concentrations as high as 912 頜/kg in the untreated material to 0.007 頜/kg in the treated soil (SoilTech no date). HTTD performance data is not available for sewage treatment sludge. SoilTech reportedly has conducted full-scale tests on municipal solid wastes; however, test resuts were not available for PRC's review. These materials may be treated if they contain or are blended with inert solids. Factors that Influence Performance The degree to which an HTTD system is able to remove contaminants from wastes and remain cost effective depends on certain key characteristics, including the moisture content of the waste, the boiling points of the contaminants, the hydrocarbon content of the waste, and the particle size distribution and soil classification of the waste being treated. These characteristics are described below. Moisture Content In the HTTD process, excess moisture is removed at the expense of excess burner fuel and can affect treatment performance. Depending on the specific HTTD system being used, the feed material should contain 10 to 20 percent moisture before entering the system. HTTD technologies can treat wastes that contain more than 20 percent moisture; however, pretreating wastes that contain more than 20 percent moisture improves process efficiency. Pretreatment methods include filter pressing wastes, air drying wastes, blending wastes with dryer materials, and mixing with treated fines. The moisture content of most of the contaminated material from the six CD sites except the lagoon sludge is not expected to cause problems during HTTD treatment. The lagoon sludge, even when dewatered, will contain a significant amount of moisture. The lagoon sludge should be blended with dryer material for treatment. Controlled air drying and blending should be considered to reduce the moisture content of the PCB-contaminated material. Site wastes may contain significant levels of VOCs; therefore VOC emissions may hamper air drying and blending operations. Site wastes may also contain asbestos and metals, and air drying and blending may result in significant and potentially harmful inorganic emissions to the air. All drying and blending operations should be conducted in a controlled environment. Boiling Points of Contaminants For effective desorption of contaminants from soil, an HTTD system should be operated at temperatures exceeding the boiling points of the contaminants in the soil. PCBs are the primary organic contaminants of concern at the CD sites. Commercial PCBs were produced by collecting boiling point fractions during distillation of chlorinated biphenyl mixtures. Table 2-10 presents the molecular weight, boiling point range, vapor pressure, and vaporization rate for various Aroclors. In general, the boiling point range increases and the vapor pressure and vaporization rate decrease with increasing molecular weight. Therefore, it is expected that more highly chlorinated Aroclors would be more difficult to remove from waste than less chlorinated Aroclors. Similarly, more chlorinated isomer groups such as octachlorinated biphenyls are expected to be harder to remove than less chlorinated isomer groups such as trichlorinated biphenyls. The principal Aroclor detected at the CD sites was Aroclor 1248. Therefore, an HTTD system should be operated at temperatures exceeding about 750 澹 to effectively remove PCBs from contaminated materials at the sites. Higher HTTD temperatures will be required to remove dioxins and furans, which have boiling points estimated to be as high as 1,000 澹. Hydrocarbon Content Contaminated sites typically contain "hot spots" where contamination levels are much higher than in surrounding areas. Hot spot soils have elevated heat values and can cause fluctuations in the treatment system temperature if not combined with less-contaminated material. In order to achieve uniform feed material characteristics, excavated material containing high levels of organic or oily wastes typically must be blended before being fed to the primary desorption chamber. Different systems have allowable maximum feed concentrations ranging from 3 to 25 percent hydrocarbons by weight. Daily sampling and analysis of the blended, stockpiled material for contaminant concentration and moisture content is typically performed by an on-site laboratory before processing to ensure uniform feed material. For a given volume of contaminated soil, a specific volume of gases will be created from vaporized moisture, volatilized contaminants, and products of combustion from the primary chamber burners. The concentration of the volatilized contaminants in the gas stream would determine the lower explosive limit (LEL) of the gas. The LEL is a limiting safety factor associated with low-temperature thermal treatment systems and directly relates to processing rates at specific contaminant levels. In practice, vapor concentrations should be limited to 25 percent of the LEL. Higher levels of organics may be allowed in the desorption unit if oxygen is maintained at low levels in the system. For example, a nitrogen purge gas is used in the RUST X*TRAX system to maintain low concentrations of oxygen. The wastes at the CD sites are expected to be very heterogeneous, and the hydrocarbon content of the contaminated materials are likely to vary significantly. Care should be taken to blend hot spot soils to lower the hydrocarbon content of wastes fed to the thermal desorber. Particle Size Distribution and Soil Classification Care must be taken to properly prepare the contaminated material for treatment. For optimum treatment, feed consistency should be as uniform as possible. Preparation of soils may be needed to ensure that the material is properly sized. By screening or grinding, particles can be reduced to a uniform size of less than 0.5 to 2.5 inches in diameter, depending on the requirement of the system used. Large clumps should not be fed into the HTTD system because some contaminants could remain in the soil because of inefficient heat transfer in the soil particle. Soils with high silt and clay content of greater than 20 to 30 percent and gummy solids may reduce process throughput and increase treatment costs. Heavy clays may need to be processed in a mixer with other materials such as dry sand to achieve a semi-flowable solid. In addition, contaminants tend to be adsorbed onto smaller soil particles because such particles have a larger surface area with more active sites available for contaminant sorption and chemical and physical bonding. Because fine-grained soils such as clayey soil have more active sorption sites, they are typically more difficult to treat than coarser soil and sediment that contain an equal concentration of contaminants. Soil samples collected from the CD sites indicate that site soils consist primarily of clay and silty clay. In addition, large pieces of bedrock may be intermingle with the soils. Materials blending would most likely be necessary to improve soil transport through the HTTD system. System Limitations HTTD technology is not effective in removing nonvolatile inorganic contaminants such as metal wastes (except for mercury, which has a boiling point of 674 澹). Studies indicate that metals in the leachate from the TCLP generally do not increase in concentration after treatment. Although nonvolatile inorganic contaminants such as metals are not removed, they do not inhibit the process when treating organic contaminants. The contaminated solid waste may also contain asbestos. HTTD is not effective for treating asbestos-contaminated wastes. Materials that are difficult to treat include tars and substances that form tars at low temperatures and at relatively short exposure times. The technology is most effective on matrixes that are nonadsorptive and of low porosity. Sands are easily treated because contaminants are easily desorbed from the surface. Materials that are difficult to treat include humus, organic decay products, wood, and industrial adsorbents. 4.4.1.4 Reduction of Mobility, Toxicity, or Volume Through Treatment -- Alternative 1 This evaluation criterion addresses the statutory preference for selecting remedial actions that employ treatment technologies that permanently and significantly reduce the toxicity, mobility, or volume of hazardous substances. This preference is satisfied when treatment reduces the principal threats at a site through destruction of toxic contaminants, reduction of the total mass of toxic contaminants, irreversible reduction in contaminant mobility, or reduction of the total volume of contaminated media. HTTD systems reduce the toxicity and volume of contaminated material by thermally desorbing contaminants from the waste matrix in the processor and concentrating them in oils or aqueous streams in the condensation systems. HTTD is not an immobilization technology; therefore, the mobility of contaminants is not reduced. The ability of thermal desorbers to reduce the toxicity or volume of contamination at a site is assessed based on the following considerations: Reduction in toxicity of contaminated material Irreversibility of treatment Reduction in volume of contaminated materials Each of these considerations is discussed below. Reduction in Toxicity of Contaminated Material In most cases, HTTD systems physically remove contaminants from materials without altering the composition or toxicity of the contaminants. Results from a variety of SITE demonstrations and full-scale cleanup studies indicate that HTTD systems can effectively remove VOCs, SVOCs, PCBs, and furans to low residual concentrations or to below detection limits in treated solids. The contaminants are condensed in the vapor recovery system and require off-site incineration to destroy them. Irreversibility of Treatment HTTD systems permanently remove contaminants from wastes. Desorption is a physical method of treating wastes that relies on applying heat to waste to vaporize and thereby remove contaminants from the waste. The contaminants are not chemically altered; that is, their chemical structure is not changed. Instead, their physical state is changed. The contaminants transform from a liquid or solid adsorbed to a solid matrix such as soil to a gaseous phase that is removed from the HTTD processor and condensed. Reduction in Volume of Contaminated Materials The volume of contaminated materials is reduced by HTTD through the vaporization of contaminants and condensation in a vapor recovery system, thereby transferring the contaminants from a solid matrix to a liquid matrix. The concentrations of the contaminants in the oil and water from the vapor recovery system depend on the solubility of the contaminants. VOCs are generally more soluble in water than are SVOCs; therefore, the condensed water stream is likely to contain higher concentrations of VOCs than SVOCs. SVOCs tend to accumulate in the oil phase. During the Waukegan Harbor Superfund site remediation, the ATP system treated 12,755 tons of contaminated soil and sediment at feed PCB concentrations of about 1 percent. About 200 tons of waste oil was generated during the remediation of the site. Other ATP treatment residuals contaminated with significant amounts of PCBs, including the activated carbon from ATP's flue gas and water treatment systems and preheat cyclone fines, were recycled to the ATP for treatment. Therefore, the amount of contaminated material was reduced to about 1.5 percent of the original amount of contaminated soil and sediment. 4.4.1.5 Short-Term Effectiveness -- Alternative 1 The potential short-term effectiveness of the HTTD technology application involves worker safety considerations and potential community exposure. The technology's impact on these areas is discussed below. Worker Safety Worker safety considerations associated with application of HTTD systems can be grouped in two categories: (1) general site hazards and (2) potential chemical hazards. General site hazards include the following: Heavy equipment hazards Occupational noise exposure Potential slip, trip, or fall hazards Potential for contact with underground or overhead mechanical and electrical hazards or utility lines Airborne dust hazards Potential splashing of hazardous liquids Heat and cold stress Exposure to physical hazards is reduced by providing (1) appropriate safety equipment for noise, dust, and liquid exposure, and (2) awareness training to orient personnel with the physical hazards in the workplace. Potential chemical hazards include inhalation, absorption, ingestion, and contact with constituents of concern in contaminated material. For HTTD systems, the likelihood for these types of exposure is highest during handling of untreated wastes and waste oil. Exposure to chemical hazards can be reduced by conducting waste and oil handling in well-ventilated areas, providing appropriate health and safety equipment, and conducting ambient air and personnel monitoring. Potential Community Exposure Potential community exposure to health hazards from the application of an HTTD system could include exposure to stack gas and fugitive dust emissions. These potential exposures can be minimized by developing standards for stack gas and dust emissions at each site. These standards must be approved by EPA, IDEM, and local authorities before remediation begins. Compliance with the standards should be demonstrated during POP testing and by testing during remedial activities. Potential community exposure to stack gas and fugitive dust emissions are discussed below. Exposure to Stack Gas Emissions Exposure to stack gas emissions primarily depends on (1) the concentration of contaminants in stack gas emissions and (2) the proximity of the treatment system to potential receptors. Stack gas samples typically are collected during initial POP testing at the beginning of treatment operations and during other testing. Stack gas sampling results from the Waukegan Harbor, Re-Solve, and Acme sites are presented in Table 4-5. Before an HTTD system is designed or selected, additional waste characterization data are required to select the appropriate APC equipment. Cyclones, baghouses, or venturi scrubbers are typically used to remove particulates in the off-gas from the HTTD unit; and direct- contact scrubbers, condensers, chillers, and carbon adsorption systems are typically used to remove organics from the vapor stream. Volatile metals and acid gases are typically treated using an acid gas scrubber. Site-specific equipment and stack testing would be required if HTTD is used to treat the contaminated materials from the six CD sites. The proposed CTF is located in a predominantly rural area that is 7 miles southwest of the City of Bloomington. Approximately 1,500 people live in the site area, which has an area of 7 square miles and is defined as the two census block groups immediately adjacent to the site. Residents in the area may potentially be exposed to emissions from the HTTD system stack. Testing and air dispersion modeling is required to ensure that the community would not be exposed to harmful concentrations of chemicals from the stack. Exposure to Fugitive Dust Emissions Fugitive emissions are a concern at the feed and discharge points of the HTTD system. Fugitive emissions at the feed point may include VOC and SVOC vapors and particulates containing SVOCs and metals. Fugitive emissions from the discharge point may contain particulate metals. Fugitive emissions at the feed point of the HTTD would be controlled by enclosing screens and feed conveyors, and fugitive emissions from the discharge point of the HTTD system should be controlled by quenching hot, dry solids. Because the soil and sediment to be treated contains a significant amount of fines, an enclosed conveyor should be used to transport soils from the HTTD processor to a roll-off box or similar container to reduce the potential for dust emissions. 4.4.1.6 Implementability -- Alternative 1 Implementation considerations for HTTD systems include technical feasibility, administrative feasibility, and availability of services and materials. Additional information is also needed to implement HTTD systems. These considerations are discussed below. Technical Feasibility The technical feasibility of implementing the HTTD technology depends on (1) operating experience and technical difficulties, and (2) system reliability. These considerations are discussed below. Operating Experience and Technical Difficulties HTTD systems have been widely used during the past 5 years to remediate hazardous waste sites containing organic contaminants. Therefore, a significant amount of knowledge concerning the operation of the systems has been gained. The systems are highly automated and automatically shut down when lower or higher than desired temperatures occur and when positive pressure occurs in the processor. Because of this automation, most HTTD systems are technically easy to control. However, heterogenous wastes containing various amounts of hydrocarbons, moisture, or material types may increase the difficulty of maintaining steady temperatures and pressures in the processor; therefore, contaminated materials should be blended or mixed with treated inert material for better control of the system. System Reliability During POP testing at the Waukegan Harbor Superfund site, the ATP system had problems meeting the site-specific requirement for the PCB DRE of 99.9999 percent and total dioxin and furan emissions requirement of 30 ng/dscm at 7 percent oxygen. Process modifications implemented in March 1992 resulted in improvements in ATP stack emissions. The process modifications included the following: The carbon bed depth in the stack was increased to 24 inches. The scrubber was taken out of service and converted to an adsorption unit by addition of two new carbon beds to the scrubber. The retort zone residence time was increased by reducing the amount of solids recycled from the combustion zone to the retort zone through the sand seal. Activated carbon beds were installed in the preheat and retort zone noncondensable vapor return lines to the burners. The burners were operated at their maximum capacity to maintain the combustion zone temperature at the maximum operating level. Possible leaks in the GAC adsorption system were sealed. These process modifications enabled the ATP system to meet the PCB DRE and dioxin and furan emissions requirements at the Waukegan Harbor Superfund site. On-line percentage, the percentage of time that a system operates, is one measure of the reliability of a treatment system. SoilTech reports achieving an on-line system percentage of 85 percent at the Waukegan Harbor Superfund site. Administrative Feasibility The administrative feasibility of HTTD depends primarily on the ability of an HTTD system to receive all necessary federal, state, and local permits. The HTTD system would have to be tested to evaluate whether the system can meet the required performance standard for PCB removal of 2 ppm. Availability of Services and Materials HTTD services and materials are readily available. Many companies offer preconstructed HTTD equipment. Most HTTD systems can be transported on trailers and be assembled at the site. Because HTTD systems have been used at a significant number of Superfund sites, many experienced operators are also available. Operation of many HTTD systems requires maintenance supplies and services such as welding supplies and tools, PPE, and leased equipment such as front-end loaders. An adequate supply of spare parts such as pumps, flow meters, and piping should also be available from an on-site supply or from a nearby industrial supply center. For hollow-auger heating systems, additional heating fluid should be kept on site to replenish minor losses in the heating system. Additional Information Needed to Implement High Temperature Thermal Desorption Additional information, especially additional waste characterization, is needed to evaluate the technical feasibility of implementing the HTTD technology to treat wastes from the six CD sites. For wastes that contain a large concentration of organics such as the solid waste and sludge, waste characterization studies should be conducted to determine the British thermal unit (Btu) content, ash content, and moisture content. An ultimate analysis should also be conducted to determine the elemental makeup of the solid waste and sludge. These parameters are important to evaluate the heating and cooling requirements for the HTTD system. The particle size distribution of all contaminated materials should also be determined to estimate the amount of fines in the contaminated materials. 4.4.1.7 Cost -- Alternative 1 The total capital and O&M costs, and NPV for HTTD treatment are shown in Table 4-6 and detailed in Appendix C. Total fixed costs are $1,260,000. The annual O&M costs are $8,710,000. The NPV has been estimated for Scenario 1 and 2 for a period of 6 and 9 years, respectively, discounted at a rate of 7.5 percent. The NPV of all costs for Alternative 1 including material handling costs and treatment and disposal costs is $ 128,000,000 and $157,000,000 for Scenario 1 and 2, respectively.