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 Engineering Bulletin 
 
 Solidification/Stabilization 
 
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 Purpose 
 
 Section 121(b) of the Comprehensive Environmental Re¬ 
 sponse, Compensation, and Liability Act (CERCLA) mandates 
 the Environmental Protection Agency (EPA) to select remedies 
 that "utilize permanent solutions and alternative treatment 
 technologies or resource recovery technologies to the maxi¬ 
 mum extent practicable" and to prefer remedial actions in 
 which treatment "permanently and significantly reduces the 
 volume, toxicity, or mobility of hazardous substances, pollut¬ 
 ants, and contaminants as a principal element." The Engineer¬ 
 ing Bulletins are a series of documents that summarize the most 
 current information available on selected treatment and site 
 remediation technologies and related issues. They provide 
 summaries of and references for this information to help reme¬ 
 dial project managers, on-scene coordinators, contractors, and 
 other site cleanup managers understand the type of data and 
 site characteristics needed to evaluate a technology for poten¬ 
 tial applicability to their Superfund or other hazardous waste 
 site. Those documents that describe individual treatment tech¬ 
 nologies focus on remedial investigation scoping needs. Ad¬ 
 denda are issued periodically to update the original bulletins. 
 
 granular consistency resembling soil. During in situ operations, 
 S/S agents are injected Into and mixed with the waste and soil 
 up to depths of 30 to 100 feet using augers. 
 
 Treatability studies are the only means of documenting the 
 applicability and performance of a particular S/S system. Deter¬ 
 mination of the best treatment alternative will be based on 
 multiple site-specific factors and the cost and efficacy of the 
 treatment technology. The EPA contact identified at the end of 
 this bulletin can assist in the location of other contacts and 
 sources of information necessary for such treatability studies. 
 
 It may be difficult to evaluate the long-term (>5 year) 
 performance of the technology. Therefore, long-term monitor¬ 
 ing may be needed to ensure that the technology continues to 
 function within its design criteria. 
 
 This bulletin provides information on technology applica¬ 
 bility, the limitations of the technology, the technology descrip¬ 
 tion, the types of residuals produced, site requirements, the 
 process performance data, the status of the technology, and 
 sources for further information. 
 
 Abstract 
 
 Solidification refers to techniques that encapsulate hazard¬ 
 ous waste into a solid material of high structural integrity. 
 Encapsulation involves either fine waste particles 
 (microencapsulation) or a large block or container of wastes 
 (macroencapsulation) [1, p. 2]*. Stabilization refers to tech¬ 
 niques that treat hazardous waste by converting it into a less 
 soluble, mobile, or toxic form. Solidification/Stabilization (S/S) 
 processes, as referred to in this document, utilize one or both of 
 these techniques. 
 
 S/S technologies can immobilize many heavy metals, cer¬ 
 tain radionuclides, and selected organic compounds while de¬ 
 creasing waste surface area and permeability for many types of 
 sludge, contaminated soils, and solid wastes^ Common S/S 
 agents include: Type 1 Portland cement or cement kiln dust; 
 lime, quicklime, or limestone; fly ash; various mixtures of these 
 materials; and various organic binders (e.g., asphalt). The 
 mixing of the waste and the S/S agents can occur outside of the 
 ground (ex situ) in continuous feed or batch operations or in 
 the ground (in situ) in a continuous feed operation. The final 
 product can be a continuous solid mass of any size or of a 
 
 Technology Applicability 
 
 The U.S. EPA has established treatment standards under 
 the Resource Conservation and Recovery Act (RCRA), Land 
 Disposal Restrictions (LDRs) based on Best Demonstrated Avail- - 
 able Technology (BOAT) rather than on risk-based or health- 
 based standards. There are three types of LDR treatment 
 standards based on the following: achieving a specified con¬ 
 centration level, using a specified technology prior to disposal, 
 and "no land disposal." Achieving a specified concentration 
 level is the most common type of treatment standard. When a 
 concentration level to be achieved is specified for a waste, any 
 technology that can meet the standard may be used unless that 
 technology is otherwise prohibited [2]. 
 
 The Superfund policy on use of immobilization is as fol¬ 
 lows: "Immobilization is generally appropriate as a treatment 
 alternative only for material containing inorganics, semi-volatile 
 and/or non-volatile organics. Based on present information, 
 the Agency does not believe that immobilization is an appropri¬ 
 ate treatment alternative for volatile organic compounds (VOCs). 
 Selection of immobilization of semi-volatile compounds (SVOCs) 
 and non-volatile organics generally requires the performance of 
 
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a site-specific treatability study or non-site-specific treatability 
 study data generated on waste which is very similar (in terms of 
 type of contaminant, concentration, and waste matrix) to that 
 to be treated and that demonstrates, through Total Waste 
 Analysis (TWA), a significant reduction (e.g., a 90 to 99 percent 
 reduction) in the concentration of chemical constituents of 
 concern. The 90 to 99 percent reduction in contaminant 
 concentration is a general guidance and may be varied within a 
 reasonable range considering the effectiveness of the technol¬ 
 ogy and the cleanup goals for the site. Although this policy 
 represents EPA's strong belief that TWA should be used to 
 demonstrate effectiveness of immobilization for organics, other 
 teachability tests may also be appropriate in addition to TWA to 
 evaluate the protectiveness under a specific management sce¬ 
 nario. "To measure the effectiveness on inorganics, the EPA's 
 Toxicity Characteristic Leaching Procedure (TCLP) should be 
 used in conjunction with other tests such as TCLP using distilled 
 water or American Nuclear Society (ANS) 16.1 [3, p. 2]. 
 
 Factors considered most important in the selection of a 
 technology are design, implementation, and performance of 
 S/S processes and products, including the waste characteristics 
 (chemical and physical), processing requirements, S/S product 
 management objectives, regulatory requirements, and econom¬ 
 ics. These and other site-specific factors (e.g., location, condi¬ 
 tion, climate, hydrology, etc.) must be taken into account in 
 determining whether, how, where, and to what extent a par¬ 
 ticular S/S method should be used at a particular site [4, p. 
 7.92]. Pozzolanic S/S processes can be formulated to set under 
 water if necessary; however, this may require different propor¬ 
 tions of fixing and binding agents to achieve the desired immo¬ 
 bilization and is not generally recommended [5, p. 21]. Where 
 non-pumpable sludge or solid wastes are encountered, the site 
 must be able to support the heavy equipment required for 
 excavation or in situ injection and mixing. At some waste 
 disposal sites, this may require site engineering. 
 
 A wide range of performance tests may be performed in 
 conjunction with S/S treatability studies to evaluate short- and 
 long-term stability of the treated material. These include total 
 waste analysis for organics, teachability using various methods, 
 permeability, unconfined compressive strength (UCS), treated 
 waste and/or leachate toxicity endpoints, and freeze/thaw and 
 wet/dry weathering cycle tests performed according to specific 
 procedures [6, p. 4.2] [7, p. 4.1]. Treatability studies should be 
 conducted on replicate samples from a representative set of 
 waste batches that span the expected range of physical and 
 chemical properties to be encountered at the site [8, p. 1]. 
 
 The most common fixing and binding agents for S/S are 
 cement, lime, natural pozzolans, and fly ash, and mixtures of 
 these [4, p. 7.86] [6, p. 2.1]. They have been demonstrated to 
 immobilize many heavy metals and to solidify a wide variety of 
 wastes including spent pickle liquor, contaminated soils, incin¬ 
 erator ash, wastewater treatment filter cake, and waste sludge 
 [7, p. 3.1] [9], S/S is also effective in immobilizing many 
 radionuclides [10], In general, S/S is considered an established 
 full-scale technology for nonvolatile heavy metals although the 
 long-term performance of S/S in Superfund applications has yet 
 to be demonstrated [2]. 
 
 Traditional cement and pozzolanic materials have yet to be 
 shown to be consistently effective in full-scale applications treat¬ 
 ing wastes high in oil and grease, surfactants, or chelating 
 agents without some form of pretreatment [11] [12, p. 122]. 
 Pretreatment methods include pH adjustment, steam or ther¬ 
 mal stripping, solvent extraction, chemical or photochemical 
 reaction, and biodegradation. The addition of sorbents such as 
 modified day or powdered activated carbon may improve ce¬ 
 ment-based or pozzolanic process performance [6, p. 2.3]. 
 
 Regulations promulgated pursuant to the Toxic Substances 
 Control Act (TSCA) do not recognize S/S as an approved treat¬ 
 ment for wastes containing polychlorinated biphenyls (PCBs) 
 above 50 ppm. ft is EPA policy that soils containing greater 
 than 10 ppm in publtc/residential areas and 25 ppm in limited 
 access/occupational areas be removed for TSCA-approved treat¬ 
 ment/disposal. However, the policy also provides EPA regional 
 offices with the option of requiring more restrictive levels. For 
 example, Region 5 requires a deanup level of 2 ppm. The 
 proper disposition of high volume sludges, soils, and sediments 
 is not specified in the TSCA regulations, but precedents set in 
 the development of various records of decision (ROOs) indicate 
 that stabilization may be approved where PCBs are effectively 
 immobilized and/or destroyed to TSCA-equivalent levels. Some 
 degree of immobilization of PCBs and related polychlorinated 
 polycyclic compounds appears to occur in cement or pozzolans 
 [15, p. 1573]. Some field observations suggest polychlorinated 
 polycydic organic substances such as PCBs undergo significant 
 levels of dechlorination under the alkaline conditions encoun¬ 
 tered in pozzolanic processes. Recent tests by the EPA, how¬ 
 ever, have not confirmed these results although significant 
 desorption and volatilization of the PCBs were documented 
 [13, p. 41] [14, p. 3]. 
 
 Table 1 summarizes the effectiveness of S/S on general 
 contaminant groups for soils and sludges. Table 1 was pre¬ 
 pared based on current available information or on professional 
 judgment when no information was available. In interpreting 
 this table, the reader is cautioned that for some primary con¬ 
 stituents, a particular S/S technology performs adequately in 
 some concentration ranges but inadequately in others. For 
 example, copper, lead, and zinc are readily stabilized by 
 cementitious materials at low to moderate concentrations, but 
 interfere with those processes at higher concentrations [12, p. 
 43]. In general, S/S methods tend to be most effective for 
 immobilizing nonvolatile heavy metals. 
 
 The proven effectiveness of the technology for a particular 
 site or waste does not ensure that it will be effective at all sites or 
 that treatment efficiencies achieved will be acceptable at other 
 sites. For the ratings used in Table 1, demonstrated effective¬ 
 ness means that at some scale, treatability tests showed that the 
 technology was effective for that particular contaminant and 
 matrix, the ratings of "Potential Effectiveness' and 'No Ex¬ 
 pected Effectiveness' are both based upon expert judgment 
 When potential effectiveness is indicated, the technology is 
 believed capable of successfully treating the contaminant group 
 in a particular matrix. When the technology is not applicable or 
 will probably not work for a particular combination of contami¬ 
 nant group and matrix, a no expected effectiveness rating is 
 given. 
 
 2 
 
 Engineering Bulletin: SoikMccriion/StabOization of Organics and Inorganics 
 
Tab** 1 
 
 Effectiveness of S/S on Sonora* Contaminant 
 Groups for Soil and Sludges 
 
 
 Contaminant Groups 
 
 Effectiveness 
 
 Soil/Sludge 
 
 
 Halogenated volatiles 
 
 □ 
 
 
 Nonhalogenated volatiles 
 
 □ 
 
 
 Halogenated semivolatiles 
 
 ■ 
 
 u 
 
 1 
 
 Nonhalogenated semivolatiles 
 
 
 and nonvolatiles 
 
 ■ 
 
 1 
 
 PCBs 
 
 ▼ 
 
 
 Pesticides 
 
 ▼ 
 
 
 Dioxins/Furans 
 
 ▼ 
 
 
 Organic cyanides 
 
 ▼ 
 
 
 Organic corrosives 
 
 ▼ 
 
 
 Volatile metals 
 
 ■ 
 
 
 Nonvolatile metals 
 
 ■ 
 
 * 
 
 Asbestos 
 
 ■ 
 
 1 
 
 Radioactive materials 
 
 ■ 
 
 
 Inorganic corrosives 
 
 ■ 
 
 
 Inorganic cyanides 
 
 ■ 
 
 d 
 
 Oxidizers 
 
 ■ 
 
 2 
 
 
 
 z 
 
 a 
 
 Reducers 
 
 ■ 
 
 d 
 
 0c 
 
 
 
 KEY: ■ Demonstrated Effectiveness: Successful treatability test 
 
 at some scale completed. 
 
 
 ▼ Potential Effectiveness 
 technology will work. 
 
 Expert opinion that 
 
 
 □ No Expected Effectiveness: Expert opinion that 
 
 
 technology will/does not work. 
 
 Another source of general observations and average re¬ 
 moval efficiencies for different treatability groups is contained 
 in the Superfund LDR Guide #6A, "Obtaining a Soil and Debris 
 Treatability Variance for Remedial Actions," (OSWER Directive 
 9347.3-06FS, September 1990) [16] and Superfund LDR Guide 
 #6B, "Obtaining a Soil and Debris Treatability Variance for 
 Removal Actions," (OSWER Directive 9347.3-06BFS, Septem¬ 
 ber 1990) [17]. Performance data presented in this bulletin 
 should not be considered directly applicable to other Superfund 
 sites. A number of variables such as the specific mix and 
 distribution of contaminants affect system performance. A 
 thorough characterization of the site and a well-designed and 
 conducted treatability study are highly recommended. 
 
 Technology Limitations 
 
 Tables 2 and 3 summarize factors that may interfere with 
 stabilization and solidification processes respectively. 
 
 Physical mechanisms that can interfere with the S/S pro¬ 
 cess include incomplete mixing due to the presence of high 
 moisture or organic chemical content resulting in only partial 
 wetting or coating of the waste particles with the stabilizing 
 and binding agents and the aggregation of untreated waste 
 into lumps [6]. Wastes with a high day content may dump, 
 interfering with the uniform mixing with the S/S agents, or the 
 day surface may adsorb key reactants, interrupting the poly¬ 
 merization chemistry of the S/S agents. Wastes with a high 
 hydrophilic organic content may interfere with solidification by 
 disrupting the gel structure of the curing cement or pozzolanic 
 mixture [11, p. 18] [18]. The potential for undermixing is 
 greatest for dry or pasty wastes and least for freely flowing 
 slurries [11, p. 13]. All in situ systems must provide for the 
 introduction and mixing of the S/S agents with the waste in the 
 proper proportions in the surface or subsurface waste site envi¬ 
 ronment Quality control is inherently more difficult with in situ 
 products than with ex situ products [4, p. 7.95]. 
 
 Chemical mechanisms that can interfere with S/S of ce¬ 
 ment-based systems include chemical adsorption, complex- 
 ation, predpitation, and nucleation [1, p. 82]. Known inor¬ 
 ganic chemical interferants in cement-based S/S processes 
 indude copper, lead, and zinc, and the sodium salts of arsen¬ 
 ate, borate, phosphate, iodate, and sulfide [6, p. 2.13] [12, p. 
 11]. Sulfate interference can be mitigated by using a cement 
 material with a low tricalcium aluminate content (e.g.. Type V 
 Portland cement) [6, p. 2.13]. Problematic organic interferants 
 indude oil and grease, phenols [8, p. 1 9\ surfactants, chelating 
 agents [11, p. 22\ and ethylene glycol [18]. For thermoplastic 
 micro- and macro-encapsulation, stabilization of a waste con¬ 
 taining strong oxidizing agents reactive toward rubber or as¬ 
 phalt must also be avoided [19, p. 10.114]. FTetreating the 
 wastes to chemically or biochemically react or to thermally or 
 chemically extract potential interferants should minimize these 
 problems, but the cost advantage of S/S may be lost, depend¬ 
 ing on the characteristics and volume of the waste and the type 
 and degree of pretreatment required. Organic polymer addi¬ 
 tives in various stages of development and field testing may 
 significantly improve the performance of the cementitious and 
 pozzolanic S/S agents with respect to immobilization of organic 
 substances, even without the addition of sorbents. 
 
 Volume increases associated with the addition of S/S agents 
 to the waste may prevent returning the waste to the landfonm 
 from which it was excavated where landfill volume is limited. 
 Where post-dosure earth moving and landscaping are required, 
 the treated waste must be able to support the weight of heavy 
 equipment The EPA recommends a minimum compressve strength 
 of 50 to 200 psi [7, p.4.13]; however, this should be a site-specific 
 determination. 
 
 Other sources of information include the U.S. EPA's Risk 
 Reduction Engineering Laboratory Treatability Database (acces¬ 
 sible via ATTIC) and the U.S. EPA Center Hill Database (contact 
 Patricia Erickson). 
 
 Environmental conditions must be considered in determin¬ 
 ing whether and when to implement an S/S technology. Ex¬ 
 tremes of heat, cold, and precipitation can adversely affect S/S 
 applications. For example, the viscosity of one or more of the 
 
 Engineering Bulletin: Soildification/Stabilization of Organics and Inorganics 
 
 3 
 
Tab*# 2. 
 
 Summary of Focton that May Interior* wtth Stabttzattoo Proc#»#s 
 
 Characteristics Affecting Processing feasibility 
 
 Potential Interference 
 
 VOCs 
 
 Volatiles not effectively immobilized; driven off by heat of reaction. 
 
 Sludges and soils containing volatile organics can be treated using a 
 heated extruder evaporator or other means to evaporate free water and 
 VOCs prior to mixing with stabilizing agents. 
 
 Use of acidic sorbent with metal hydroxide wastes 
 
 Solubilizes metal. 
 
 Use of acidic sorbent with cyanide wastes 
 
 Releases hydrogen cyanide. 
 
 Use of acidic sorbent with waste containing ammonium compounds 
 
 Releases ammonia gas. 
 
 Use of acidic sorbent with sulfide wastes 
 
 Releases hydrogen sulfide. 
 
 Use of alkaline sorbent (containing carbonates such as cakite 
 or dolomite) with acid waste 
 
 May create pyrophoric waste. 
 
 Use of siliceous sorbent (soil, fly ash) with hydrofluoric acid waste 
 
 May produce soluble fluorosiiicates. 
 
 Presence of anions in acidic solutions that form soluble 
 calcium salts (e.g., calcium chloride acetate, and bicarbonate) 
 
 Cation exchange reactions - leach calcium from S/S product 
 increases permeability of concrete. Increases rate of exchange 
 reactions. 
 
 Presence of halides 
 
 Easily leached from cement and lime. 
 
 * Adapted from reference 2 
 
 Table 3. 
 
 Summary of Factors that May Interfere with SoNdMcatton Processes * 
 
 Characteristics Affecting 
 Processing Feasibility 
 
 Potential Interference 
 
 Organic compounds 
 
 Organics may interfere with bonding of waste materials with inorganic binders. 
 
 Semivolatile organics or poly¬ 
 aromatic hydrocarbons 
 (PAHs) 
 
 Organics may interfere with bonding of waste materials. 
 
 Oil and grease 
 
 Weaken bonds between waste particles and cement by coating the particles. Decrease in unconfined 
 compressive strength with increased concentrations of oil and grease. 
 
 Fine particle size 
 
 Insoluble material passing through a No. 200 mesh sieve can delay setting and curing. Small particles 
 can also coat larger particles, weakening bonds between particles and cement or other reagents. 
 
 Particle size >1 /4 inch in diameter not suitable. 
 
 Halides 
 
 May retard setting, easily leached for cement and pozzolan S/S. May dehydrate thermoplastic 
 solidification. 
 
 Soluble salts of manganese, 
 tin, zinc, copper, and lead 
 
 Reduced physical strength of final product caused by large variations in setting time and reduced 
 dimensional stability of the cured matrix, thereby increasing teachability potential. 
 
 Cyanides 
 
 Cyanides interfere with bonding of waste materials. 
 
 Sodium arsenate, borates, 
 phosphates, iodates, sulfides, 
 and carbohydrates 
 
 Retard setting and curing and weaken strength of final product. 
 
 Sulfates 
 
 Retard setting and cause swelling and spalling in cement S/S. With thermoplastic solidification may 
 dehydrate and rehydrate, causing splitting. 
 
 * Adapted from reference 2 
 
 4 
 
 Engineering Bulletin: SoOdttcation/StabUzation of Organics and Inorganics 
 
Tabid 3 
 
 Summary o i Facto n that May Intwfar* with SoSdMcatlon Pro cd— t * (continued) 
 
 Characteristics Affecting 
 Processing Feasibility 
 
 rwi/ioor Mttfmttcncc 
 
 Phenols 
 
 Marked decreases In compressive strength for high phenol levels. 
 
 Presence of coal or lignite 
 
 Coals and lignites can cause problems with setting, curing, and strength of the end product 
 
 Sodium borate, calcium 
 sulfate, potassium 
 dichromate, and 
 carbohydrates 
 
 Interferes with pozzolanic reactions that depend on formation of calcium silicate and aluminate 
 hydrates. 
 
 Nonpolar organics (oil, 
 grease, aromatic 
 hydrocarbons, PCBs) 
 
 May impede setting of cement pozzolan, or organic-polymer S/S. May decrease long-term durability 
 and allow escape of volatiles during mixing. With thermoplastic S/S, organics may vaporize from heat 
 
 Polar organics (alcohols, 
 phenols, organic acids, 
 glycols) 
 
 With cement or pozzolan S/S, high concentrations of phenol may retard setting and may decrease short¬ 
 term durability; all may decrease long-term durability. With thermoplastic S/S, organics may vaporize. 
 
 Alcohols may retard setting of pozzolans. 
 
 Solid organics (plastics, tars, 
 resins) 
 
 Ineffective with urea formaldehyde polymers; may retard setting of other polymers. 
 
 Oxidizers (sodium 
 hypochlorite, potassium 
 permanganate, nitric acid, 
 or potassium dichromate) 
 
 May cause matrix breakdown or fire with thermoplastic or organic polymer S/S. 
 
 Metals (lead, chromium, 
 cadmium, arsenic, mercury) 
 
 May increase setting time of cements if concentration is high. 
 
 Nitrates, cyanides 
 
 Increase setting time, decrease durability for cement-based S/S. 
 
 Soluble salts of magnesium, 
 tin, zinc, copper and lead 
 
 May cause swelling and cracking within inorganic matrix exposing more surface area to leaching. 
 
 Environmental/waste 
 conditions that lower the 
 pH of matrix 
 
 Eventual matrix deterioration. 
 
 Flocculants (e.g., ferric 
 chloride) 
 
 Interference with setting of cements and pozzolans. 
 
 Soluble sulfates >0.01% in 
 soil or 150 mg/L in water 
 
 Endangerment of cement products due to sulfur attack. 
 
 Soluble sulfates >0.5% in 
 soil or 2000 mg/L in water 
 
 Serious effects on cement products from sulfur attacks. 
 
 Oil, grease, lead, copper, 
 zinc, and phenol 
 
 Deleterious to strength and durability of cement, lime/fly ash, fly ash/cement binders. 
 
 Aliphatic and aromatic 
 hydrocarbons 
 
 Increase set time for cement 
 
 Chlorinated organics 
 
 May increase set time and decrease durability of cement if concentration is high. 
 
 Metal salts and complexes 
 
 Increase set time and decrease durability for cement or day/cement. 
 
 Inorganic acids 
 
 Decrease durability for cement (Portland Type 1) or clay/cement 
 
 inorganic bases 
 
 Decrease durability for clay/cement; KOH and NaOH decrease durability for Portland cement Type III 
 and IV. 
 
 * Adapted from reference 2 
 
 Engineering Bulletin: Soildification/StabQization of Organics and Inorganics 
 
 5 
 
materials in the mixture may increase rapidly with falling tem¬ 
 peratures or the cure rate may be slowed unacceptably [20, p. 
 27], In cement-based S/S processes the engineering properties 
 of the concrete mass produced for the treatment of the waste 
 are highly dependent on the water/cement ratio and the de¬ 
 gree of hydration of the cement High water/cement ratios 
 yield large pore sizes and thus higher permeabilities [21, p. 
 1 77}. This factor may not be readily controlled in environmen¬ 
 tal applications of S/S and pretreatment (e.g., drying) of the 
 waste may be required. 
 
 Depending on the waste and binding agents involved, S/S 
 processes can produce hot gases, including vapors that are 
 potentially toxic, irritating, or noxious to workers or communi¬ 
 ties downwind from the processes [22, p. 4]. Laboratory tests 
 demonstrate that as much as 90 percent of VOCs are volatilized 
 during solidification and as much as 60 percent of the remain¬ 
 ing VOCs are lost in the next 30 days of curing [23, p. 6]. In 
 addition, if volatile substances with low flash points are in¬ 
 volved, the potential exists for fire and explosions where the 
 fuel-to-air ratio is favorable [22, p. 4], Where volatization 
 problems are anticipated, many S/S systems now provide for 
 vapor collection and treatment. Under dry and/or windy envi¬ 
 ronmental conditions, both ex situ and in situ S/S processes are 
 likely to generate fugitive dust with potentially harmful impacts 
 on occupational and public health, especially for downwind 
 communities. 
 
 Scaleup for S/S processes from bench-scale to full-scale 
 operation involves inherent uncertainties. Variables such as 
 ingredient flow-rate control, materials mass balance, mixing, 
 and materials handling and storage, along with the weather 
 compared to the more controlled environment of a laboratory, 
 all may affect the success of a field operation. These potential 
 engineering difficulties emphasize the need for a field demon¬ 
 stration prior to full-scale implementation [2]. 
 
 Technology Description 
 
 Waste stabilization involves the addition of a binder to a 
 waste to immobilize waste contaminants effectively. Waste 
 solidification involves the addition of a binding agent to the 
 waste to form a solid material. Solidifying waste improves its 
 material handling characteristics and reduces permeability to 
 leaching agents such as water, brine, and inorganic and or¬ 
 ganic acids by reducing waste porosity and exposed surface 
 area. Solidification also increases the load-bearing capacity of 
 the treated waste, an advantage when heavy equipment is 
 involved. Because of their dilution effect, the addition of bind¬ 
 ers must be accounted for when determining reductions in 
 concentrations of hazardous constituents in S/S treated waste. 
 
 S/S processes are often divided into the following broad 
 categories: inorganic processes (cement and pozzolanic) and 
 organic processes (thermoplastic and thermosetting). Generic 
 S/S processes involve materials that are well known and readily 
 available. Commercial vendors have typically developed ge¬ 
 neric processes into proprietary processes by adding special 
 additives to provide better control of the S/S process or to 
 
 enhance specific chemical or physical properties of the treated 
 waste. Less frequently, S/S processes combine organic binders 
 with inorganic binders (e.g., diatomaceous earth and cement 
 with polystyrene, polyurethane with cement, and polymer geh 
 with sScate and imie cement) [2]. 
 
 The waste can be mixed in a batch or continuous system 
 with the binding agents after removal (ex situ) or in place (in- 
 situ). In ex situ applications, the resultant slurry can be 1) 
 poured into containers (e.g., 55-gallon drums) or molds for 
 curing and then off- or onsite disposal, 2) disposed in onsite 
 waste management cells or trenches, 3) injected into the sub¬ 
 surface environment, or 4) re-used as construction material 
 with the appropriate regulatory approvals. In in situ applica¬ 
 tions, the S/S agents are injected into the subsurface environ¬ 
 ment in the proper proportions and mixed with the waste 
 using backhoes for surface mixing or augers for deep mixing 
 [5]. Liquid waste may be pretreated to separate solids from 
 liquids. Solid wastes may also require pretreatment in the form 
 of pH adjustment, steam or thermal stripping, solvent extrac¬ 
 tion, chemical reaction, or biodegradation to remove excessive 
 VOCs and SVOCs that may react with the S/S process. The type 
 and proportions of binding agents are adjusted to the specific 
 properties of the waste to achieve the desired physical and 
 chemical characteristics of the waste appropriate to the condi¬ 
 tions at the site based on bench-scale tests. Although ratios of 
 waste-to-binding agents are typically in the range of 10:1 to 
 2:1, ratios as low as 1:4 have been reported. However, projects 
 utilizing low waste-to-binder ratios have high costs and large 
 volume expansion. 
 
 Figures 1 and 2 depict generic elements of typical ex situ 
 and in situ S/S processes, respectively. Ex situ processing 
 involves: (1) excavation to remove the contaminated waste 
 from the subsurface; (2) classification to remove oversize de¬ 
 bris; (3) mixing; and (4) off-gas treatment In situ processing 
 has only two steps: (1) mixing; and (2) off-gas treatment. 
 Both processes require a system for delivering water, waste, 
 and S/S agents in proper proportions and a mixing device (e.g., 
 rotary drum paddle or auger). Ex situ processing requires a 
 system for delivering the treated waste to molds, surface 
 trenches, or subsurface injection. The need for off-gas treat¬ 
 ment using vapor collection and treatment modules is specific 
 to the S/S project 
 
 Process Residuals 
 
 Under normal operating conditions neither ex situ nor in 
 situ S/S technologies generate significant quantities of contami¬ 
 nated liquid or solid waste. Certain S/S projects require treat¬ 
 ment of the offgas. Prescreening collects debris and materials 
 too large for subsequent treatment. 
 
 If the treated waste meets the specified cleanup levels, it 
 could be considered for reuse onsite as backfill or construction 
 material. In some instances, treated waste may have to be 
 disposed of in an approved landfill. Hazardous residuals from 
 some pretreatment technologies must be disposed of accord¬ 
 ing to appropriate procedures. 
 
 6 
 
 Engineering Bulletin: Soildification/Stabilization of Organics and Inorganics 
 
Figure 1. 
 
 G*n#ric Elements of a Typical Ex Situ S/S Process 
 
 S/S Binding 
 Agent(s) 
 
 Figure 2. 
 
 G*rreric El*m*nts of a Typical In Situ S/S Process 
 
 El 
 
 Stabilized/Solidified 
 
 Media 
 
 Water—► 
 
 
 
 Off-Gas 
 
 
 Mixing 
 
 
 Treatment 
 
 S/S Binding —► 
 
 (1) 
 
 
 (optional) 
 
 Agent(s) 
 
 
 
 (2) 
 
 Residuals 
 
 Site Requirements 
 
 The site must be prepared for the construction, operation, 
 maintenance, decontamination, and ultimate decommission¬ 
 ing of the equipment. An area must be cleared for heavy 
 equipment access roads, automobile and truck parking lots, 
 material transfer stations, the S/S process equipment, set up 
 areas, decontamination areas, the electrical generator, equip¬ 
 ment sheds, storage tanks, sanitary and process wastewater 
 collection and treatment systems, workers' quarters, and ap¬ 
 proved disposal facilities (if required). The size of the area 
 required for the process equipment depends on several factors, 
 including the type of S/S process involved, the required treat¬ 
 ment capacity of the system, and site characteristics, especially 
 soil topography and load-bearing capacity. A small mobile ex 
 situ unit could occupy a space as small as that taken up by two 
 standard flatbed trailers. An in situ system requires a larger area 
 to accommodate a drilling rig as well as a larger area for auger 
 decontamination. 
 
 Process, decontamination, transfer, and storage areas should 
 be constructed on impermeable pads with berms for spill reten¬ 
 tion and drains for the collection and treatment of stormwater 
 runoff. Stormwater storage and treatment capacity require¬ 
 ments will depend on the size of the bermed area and the local 
 climate. Standard 440V, three-phase electrical service is usually 
 needed. The quantity and quality of process water required for 
 pozzolanic S/S technologies are technology-specific. 
 
 S/S process quality control requires information on the 
 range of concentrations of contaminants and potential 
 interferants in waste batches awaiting treatment and on treated 
 product properties such as compressive strength, permeability, 
 teachability, and in some instances, contaminant toxicity. 
 
 Performance Data 
 
 Most of the data on S/S performance come from studies 
 conducted for EPA's Risk Reduction Engineering Laboratory 
 under the Superfund Innovative Technology Evaluation (SITE) 
 Program. Pilot scale demonstration studies available for review 
 during the preparation of this bulletin included: Soliditech, Inc. 
 at Morganville, New jersey (petroleum hydrocarbons, PCBs, 
 other organic chemicals, and heavy metals); International Waste 
 Technologies (IWT) process using the Geo-Con, Inc. deep-soil- 
 mixing equipment, at Hialeah, Florida (PCBs, VOCs); Chemfix 
 Technologies, Inc., at Clackamas, Oregon (PCBs, arsenic, heavy 
 metals); Im-Tech (formerly Hazcon) at Douglassville, Pennsyl¬ 
 vania (oil and grease, heavy metals including lead, and low 
 levels of VOCs and PCBs); Silicate Technology Corporation 
 (STQ, at Selma, California (arsenic, chromium, copper, penta- 
 chlorophenol and associated polychlorinated dibenzofurans and 
 dibenzo-p-dioxins). The performance of each technology was 
 evaluated in terms of ease of operation, processing capacity, 
 frequency of process outages, residuals management, cost and 
 the characteristics of the treated product Such characteristics 
 
 Engineering Bulletin: Soiidification/StdbBization of Organics and Inorganics 
 
 7 
 
included weight, density, and volume changes; UCS and mois¬ 
 ture content of the treated product before and after freeze/ 
 thaw and wet/dry weathering cycles; permeability (or 
 permissivity) to water; and teachability following curing and 
 after the weathering test cycles. Leachability was measured 
 using several different standard methods, including EPA's TCLP. 
 Table 4 summarizes the SITE performance data from these sites 
 [20] [24] [25] [26] [27] [28], 
 
 A full-scale S/S operation has been implemented at the 
 Northern Engraving Corporation (NEC) site in Sparta, Wiscon¬ 
 sin, a manufacturing facility which produces metal name plates 
 and dials for the automotive industry. The following informa¬ 
 tion on the site is taken from the remedial action report. Four 
 areas at the site that have been identified as potential sources of 
 soil, groundwater, and surface water contamination are the 
 sludge lagoon, seepage pit, sludge dump site, and lagoon 
 drainage ditch. The sludge lagoon was contaminated primarily 
 with metal hydroxides consisting of nickel, copper, aluminum, 
 fluoride, iron, and cadmium. The drainage ditch which showed 
 elevated concentrations of copper, aluminum, fluoride, and 
 chromium, was used to convey effluent from the sludge lagoon 
 to a stormwater runoff ditch. The contaminated material in the 
 drainage ditch area and sludge dumpsite was then excavated 
 and transported into the sludge lagoon for stabilization with 
 the sludge present. The vendor, Geo-Con, Inc., achieved stabi¬ 
 lization by the addition of hydrated lime to the sludge. Five 
 samples of the solidified sludge were collected for Extraction 
 Procedure (EP) toxicity leaching analyses. Their contaminant 
 concentrations (in mg/I) are as follows: Arsenic (<.01); Barium 
 (.35 -1.04); Cadmium (<.005); Chromium (<.01); Lead (<.2); 
 Mercury (<.001); Selenium (<.005); Silver (<.01); and Fluoride 
 (2.6 - 4.1). All extracts were not only below the EP toxicity 
 criteria but (with the exception of fluoride) met drinking water 
 standards as well. 
 
 Approximately three weeks later UCS tests on the solidified 
 waste were taken. Test results ranged from 2.4 to 10 psi, well 
 below the goal of 25 psi. One explanation for the low UCS 
 could be due to shear failure along the lenses of sandy material 
 and organic peat-like material present in the samples. It was 
 determined that it would not be practical to add additional 
 quantities of lime into the stabilized sludge matrix because of its 
 high solids content. Therefore, the stabilized sludge matrix 
 capacity will be increased to support the clay cap by installing 
 an engineered subgrade for the cap system using a stabilization 
 fabric and aggregate prior to cap placement [29]. 
 
 The Industrial Waste Control (IWC) Site in Fort Smith, 
 Arkansas, a closed and covered industrial landfill built in an 
 abandoned surface coal mine, has also implemented a full-scale 
 S/S system. Until 1978 painting wastes, solvents, industrial 
 process wastes, and metals were disposed at the site. The 
 primary contaminants of concern were methylene chloride, 
 ethylbenzene, toluene, xylene, trichloroethane, chromium, and 
 lead. Along with S/S of the onsite soils, other technologies used 
 were: excavation, slurry wall, french drains, and a landfill cover. 
 Soils were excavated in the contaminated region (Area C) and a 
 total of seven lifts were stabilized with flyash on mixing pads 
 previously formed. A clay liner was then constructed in Area C 
 to serve as a leachate barrier. After the lifts passed the TCLP test 
 
 they were taken to Area C for in situ solidification. Portland 
 cement was added to solidify each lift and they obtained the 
 UCS goal of 125 psi. With the combination of the other tech¬ 
 nologies, the overall system appears to be functioning properly 
 [30], 
 
 Other Superfund sites where full scale S/S has been com¬ 
 pleted to date include Davie Landfill (82,158 yd 3 of sludge 
 containing cyanide, sulfide, and lead treated with Type I Port¬ 
 land cement in 45 days) [31J; Pepper's Steel and Alloy (89,000 
 yd 3 of soil containing lead, arsenic, and PCBs treated with 
 Portland cement and fly ash) [32]; and Sapp Battery and 
 Salvage (200,000 yd 3 soil fines and washings containing lead 
 and mercury treated with Portland cement and fly ash in roughly 
 18 months) [33], ail in Region 4; and Bio-Ecology, Inc. (about 
 2P,000 yd 3 of soils, sludge, and liquid waste containing heavy 
 metals, VOCs, and cyanide treated with cement kiln flue dust 
 alone or with lime) in Region 6 [34], All sites required that the 
 waste meet the appropriate leaching test and UCS criteria. At 
 the Sapp Battery site, the waste also met a permeability crite¬ 
 rion of 10^ cm/s [33]. Past remediation appraisals by the 
 responsible remedial project managers indicate the S/S tech¬ 
 nologies are performing as intended. 
 
 RCRA LDRs that require treatment of wastes based on 
 BOAT levels prior to land disposal may sometimes be deter¬ 
 mined to be Applicable or Relevant and Appropriate Require¬ 
 ments (ARARs) for CERCLA response actions. S/S can produce a 
 treated waste that meets treatment levels set by BDAT but may 
 not reach these treatment levels in all cases. The ability to meet 
 required treatment levels is dependent upon the specific waste 
 constituents and the waste matrix. In cases where S/S does not 
 meet these levels, it still may in certain situations be selected for 
 use at a site if a treatability variance establishing alternative 
 treatment levels is obtained. Treatability variances may be 
 justified for handling complex soil and debris matrices. The 
 following guides describe when and how to seek a treatability 
 variance for soil and debris: Superfund LDR Guide #6A, 'Ob¬ 
 taining a Soil and Debris Treatability Variance for Remedial 
 Actions' (OSWER Directive 9347.3-06FS) [16] and Superfund 
 LDR Guide #6B, 'Obtaining a Soil and Debris Treatability Vari¬ 
 ance for Removal Actions' (OSWER Directive 9347.3-06BFS) 
 [17]. Another approach could be to use other treatment tech¬ 
 niques in conjunction with S/S to obtain desired treatment 
 levels. 
 
 Technology Status 
 
 In 1990,24 ROOs identified S/S as the proposed remediation 
 technology [35]. To date only about a dozen Superfund sites 
 have proceeded through full-scale S/S implementation to the 
 operation and maintenance (O&M) phase, and many of those 
 were small pits, ponds, and lagoons. Some involved S/S for off¬ 
 site disposal in RCRA-permitted facilities. Table 5 summarizes 
 these sites where full scale S/S has been implemented under 
 CERCLA or RCRA [7, p. 3-4]. 
 
 More than 75 percent of the vendors of S/S technologies 
 use cement-based or pozzolanic mixtures [11, p. 2]. Organic 
 polymen have been added to various cement-based systems to 
 enhance performance with respect to one or more physical or 
 
 8 
 
 Engineering Bulletin: SoOdlfication/Stabaization of Organics and Inorganics 
 
Table 4. Summary.of SITE Performance Data 
 
 Engineering Bulletin: Soildification/Stabilization of Organics and Inorganics 
 
 9 
 
 TCLP - Toxicity Characteristic Leaching Procedure 
 TWA - Total Waste Analysis 
 
Tctot* 5. Summary of Full Scale S/S Site* 
 
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 10 
 
 Engineering Bulletin: Soildlfication/StabOization of Organics and Inorganics 
 
chemical characteristics, but only mixed results have been 
 achieved. For example, tests of standardized wastes treated in 
 a standardized fashion using acrylonitrile, vinyl ester, polymer 
 cement, and water-based epoxy yielded mixed results. Vinyl 
 and plastic cement products achieved superior UCS and leach- 
 ability to cement-only and cement-fly ash S/S, white the acry¬ 
 lonitrile and epoxy polymers reduced UCS and increased teach¬ 
 able TOC, in several instances by two or three orders of 
 magnitude [36, p. 156]. 
 
 The estimated cost of treating waste with S/S ranges from 
 $50 to 250 per ton (1992 dollars). Costs are highly variable 
 due to variations in site, soil, and contaminant characteristics 
 that affect the performance of the S/S processes evaluated. 
 Economies of scale likely to be achieved in full-scale operations 
 are not reflected in pilot-scale data. 
 
 EPA Contact 
 
 Acknowledgments 
 
 This bulletin was prepared for the US Environmental Pro¬ 
 tection Agency, Office of Research and Development (ORD), 
 Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio, 
 by Science Applications International Corporation (SAIQ under 
 contract No. 68-C8-0062 (WA 2-22). Mr. Eugene Harris served 
 as the EPA Technical Project Manager. Mr. Cary Baker was 
 SAJC's Work Assignment Manager. This bulletin was written by 
 Mr. Larry Fink and Mr. George Wahl of SAJC. The authors are 
 especially grateful to Mr. Carlton WUes and Mr. Edward Bates of 
 EPA, RREL and Mr. Edwin Barth of EPA, CER1, who have contrib¬ 
 uted significantly by serving as technical consultants during the 
 development of this document 
 
 The following other EPA and contractor personnel have 
 contributed their time and comments by participating in the 
 expert review meetings or peer reviews of the document 
 
 University of Cincinnati 
 Battel te 
 SAIC-Raleigh 
 SAIC-Raleigh 
 SAIC-Cincinnati 
 SAIC-Cincinnati 
 
 Management Branch 
 
 Risk Reduction Engineering Laboratory 
 
 5955 Center Hill Road 
 
 Cincinnati, OH 45224 
 
 Telephone: (513) 569-7795 or (513) 569-7884 
 
 Technology-specific questions regarding S/S may be di¬ 
 rected to: 
 
 Carlton C. Wiles or Patricia M. Erickson 
 U.S. Environmental Protection Agency 
 Municipal Solid Waste and Residuals 
 
 Dr. Paul Bishop 
 Dr. Jeffrey Means 
 Ms. Mary Boyer 
 Mr. Cecil Cross 
 Ms. Margaret Croeber 
 Mr. Eric Saylor 
 
 Engineering Bulletin: Soikfflcatton/StabBization of Organics and Inorganics 
 
 11 
 
REFERENCES 
 
 1. Conner, J.R. Chemical Fixation and Solidification of 
 Hazardous Wastes, Van Nostrand Reinhold, New York, 
 
 1990. 
 
 2. Technical Resources Document on Solidification/Stabiliza¬ 
 tion and its Application to Waste Materials (Draft), 
 Contract No. 68-CO-0003, Office of Research and 
 Development, U.S. Environmental Protection Agency, 
 Cincinnati, Ohio, 1991. 
 
 3. Guidance on Key Terms. Office of Solid Waste and 
 Emergency Response. U.S. Environmental Protection 
 Agency. Directive No. 9200.5-220, Washington, D.C., 
 
 1991. 
 
 4. Wiles, C.C. Solidification and Stabilization Technology. In: 
 Standard Handbook of Hazardous Waste Treatment and 
 Disposal, H.M. Freeman, Ed., McGraw Hill, New York, 
 1989. 
 
 5. Jasperse, B.H. Soil Mixing, Hazmat World, November 
 1989. 
 
 6. Handbook for Stabilization/Solidification of Hazardous 
 Waste. EPA/540/2-86/001, U.S. Environmental Protection 
 Agency, Cincinnati, Ohio, June 1986. 
 
 7. Stabilization/Solidification of CERCLA and RCRA Wastes; 
 Physical Tests, Chemical Testing Procedures, Technology, 
 and Field Activities. EPA/625/6-89/022, U.S. Environmen¬ 
 tal Protection Agency, Cincinnati, Ohio, May 1990. 
 
 6. Wiles, C.C. and E. Barth. Solidification/Stabilization: Is It 
 Always Appropriate? Pre-Publication Draft, American 
 Society of Testing and Materials, Philadelphia, Pennsylva¬ 
 nia, December 1990. 
 
 9. Superfund Treatability Clearinghouse Abstracts. EPA/540/ 
 2-89/001, U.S. Environmental Protection Agency, 
 Washington, D.C., August 1989. 
 
 10. Kasten, J.L, H.W. Godbee, T.M. Gilliam, and S.C. 
 
 Osborne, 1989. Round I Phase I Waste Immobilization 
 Technology Evaluation Subtask of the Low-Level Waste 
 Disposal Development and Demonstration Program, 
 Prepared by Oak Ridge National Laboratories, Martin 
 Marietta Energy Systems, Inc., Oak Ridge, Tennessee, for 
 Office of Defense and Transportation Management under 
 Contract DE-AC05-840R21400, May 1989. 
 
 11. |ACA Corporation. Critical Characteristics and Properties 
 of Hazardous Soiidification/Stabiiization. Prepared for 
 Water Engineering Research Laboratory, Office of 
 Research and Development, U.S. Environmental Protec¬ 
 tion Agency, Cincinnati, Ohio. Contract No. 68-03-3186, 
 1985. 
 
 12. Bricka, R.M., and LW. Jones. An Evaluation of Factors 
 Affecting the Solidification/Stabilization of Heavy Metal 
 Sludge, Waterways Experimental Station, U.S. Army 
 Corps of Engineers, Vicksburg, Mississippi, 1989. 
 
 13. Fate of Polychlorinated Biphenyls (PCBs) in Soil Following 
 Stabilization with Quicklime, EPA/600/2-91/052, U.S. 
 Environmental Protection Agency, Cincinnati, Ohio, 
 September 1991. 
 
 14. Convery, J. Status Report on the Interaction of PCB's and 
 Quicklime, Risk Reduction Engineering Laboratory, Office 
 of Research and Development, U.S. Environmental 
 Protection Agency, Cincinnati, Ohio, June 1991. 
 
 15. Stinson, M.K. EPA SITE Demonstration of the Interna¬ 
 tional Waste Tech oologies/Geo-Con In Situ Stabilization/ 
 Solidification Process. Air and Waste Management J., 
 40(11): 1569-1576. 
 
 16. Superfund LDR Guide #6A (2nd edition), "Obtaining a 
 Soil and Debris Treatability Variance for Removal Ac¬ 
 tions', OSWER. Directive 9347.3-06FS, September 1990. 
 
 17. Superfund LDR Guide #68, "Obtaining a Soil and Debris 
 Treatability Variance for Removal Actions', OSWER 
 Directive 9347.3-06BFS, September 1990. 
 
 18. Chasalani, D., F.K. Cartiedge, H.C. Eaton, M.E. 
 Tittlebaum, and M.B. Walsh. The Effects of Ethylene 
 Glycol on a Cement-Based Solidification Process. Hazard¬ 
 ous Waste and Hazardous Materials. 3(2): 167-173, 
 1986. 
 
 19. Handbook of Remedial Action at Waste Disposal Sites. 
 EPA/625/6-85/006, U.S. Environmental Protection 
 Agency, Cincinnati, Ohio, June 1985. 
 
 20. Technology Evaluation Report SITE Program Demonstra¬ 
 tion Test Soliditech, Inc. Soiidification/Stabiiization 
 Process, Volume I. EPA/540/5-89/005a, U.S. Environ¬ 
 mental Protection Agency, Cincinnati, Ohio, February 
 1990. 
 
 21. Kirk-Othmer. Cement Encyclopedia of Chemical 
 Technology, 3rd Ed., John Wiley and Sons, New York: 
 163-193,1981. 
 
 22. SoundararaJan, R., and J.J. Gibbons, Hazards in the 
 Quicklime Stabilization of Hazardous Waste. Unpublished 
 paper delivered at the Gulf Coast Hazardous Substances 
 Research Symposium, February 1990. 
 
 23. Weitzman, L, LR. Hamel., and S. Cadmus. Volatile 
 Emissions From Stabilized Waste, Prepared By Acurex 
 Corporation Under Contract No. 68-02-3993 (32, 37) for 
 the Risk Reduction Engineering Laboratory, Office of 
 Research and Development U.S. Environmental Protec¬ 
 tion Agency, Cincinnati, Ohio, May 1989. 
 
 12 
 
 Engineering Bulletin: SoBdlfication/Stabttzation of Organics and Inorganics 
 
24. Technology Evaluation Report SITE Program Demonstra¬ 
 tion Test International Waste Technologies In Situ 
 Stabilization/Solidification - Hialeh, Florida, Volume I. 
 EPA/540/5-89/004a, U.S. Environmental Protection 
 Agency, Cincinnati, Ohio, June 1989. 
 
 25. Technology Evaluation Report Chemfix Technologies, 
 Inc. Solidification/Stabilization Process - Clackamas, 
 Oregon, Volume I. EPA/540/5-89/011 a, U.S. Environ¬ 
 mental Protection Agency, Cincinnati, Ohio, September 
 1990. 
 
 26. Technology Evaluation Report SITE Program Demonstra¬ 
 tion Test, HAZCON Solidification, Douglassville, Pennsyl¬ 
 vania, Volume I. EPA/540/5-89/001 a, U.S. Environmen¬ 
 tal Protection Agency, Washington, D.C., February 1989. 
 
 27. Bates, E.R., P.V. Dean, and I. Klich, Chemical Stabilization 
 of Mixed Organic and Metal Compounds: EPA SITE 
 Program Demonstration of the Silicate Technology 
 Corporation Process. Journal of the Air & Waste Manage¬ 
 ment Association. 42(5): 724-728, 1992. 
 
 28. Applications Analysis Report. Silicate Technology 
 Corporation. Solidification/Stabilization Technology for 
 Organic and Inorganic Contaminants in Soils, EPA/540/ 
 AR-92/010, U.S. Environmental Protection Agency. 
 Washington, D.C., December 1992. 
 
 29. Eder Associates Consulting Engineers, P.C. Northern 
 Engraving Corporation Site Remedial Action Report. 
 
 Sparta, Wisconsin, 1989. 
 
 30. Remedial Construction Report Industrial Waste Control 
 Site. Fort Smith, Arkansas. U.S. Environmental Protection 
 Agency, 1991. 
 
 31. Jackson, R. RPM, Davie Landfill, Florida. Personal 
 Communication. Region 4, U.S. Environmental Protection 
 Agency, Atlanta, Georgia, August 1991. 
 
 32. Scott, D. RPM, Pepper's Steel and Alloy. Personal 
 Communication. Region 4, U.S. Environmental Protection 
 Agency, Atlanta, Georgia, October 1991. 
 
 33. Berry, M. RPM, Sapp Battery and Salvage, Florida. 
 Personal Communication. Region 4, U.S. Environmental 
 Protection Agency, Atlanta, Georgia, August 1991. 
 
 34. Pryor, C. RPM, Bio-Ecology Systems, Texas. Personal 
 Communication. Region 6, U.S. Environmental Protection 
 Agency, Dallas, Texas, August 1991. 
 
 35. Rod Annual Report; FY1990. EPA/540/8-91/067, U.S. 
 Environmental Protection Agency, Washington D.C., July, 
 1991. 
 
 36. Kyles, J.H., K.C. Malinowski, J.S. Leithner, and T.F. 
 
 Stanczyk. The Effect of Volatile Organic Compounds on 
 the Ability of Solidification/Stabilization Technologies To 
 Attentuate Mobile Pollutants. In: Proceedings of the 
 National Conference on Hazardous Waste and Hazardous 
 Materials. Hazardous Materials Control Research Institute, 
 Silver Springs, MD, March 16-18, 1987. 
 
 Engineering Bulletin: Solidification/Stabilization of Organics and Inorganics 
 
 13 
 
 ☆ l.s. government printing office: im • 750-on/wxm 
 
* 
 
TECHNICAL REPORT DATA 
 
 (Please read Instructions on the reverse before complet 
 
 mi iii mini 
 
 i. REPORT no. 2. 
 
 EPA/540/S-92/015 
 
 3 . iii linn mi 
 
 PB9 
 
 mi iniiiiiii 
 
 4-106333 
 
 4. TITLE AND SUBTITLE 
 
 Engineering Bulletin 
 
 Solidification/Stabilization of Organics and Inorganic 
 
 5 REPORT DATE 
 
 9/92 
 
 ft. PERFORMING ORGANIZATION CODE 
 
 5 
 
 7. AUTHOR(S) 
 
 Various 
 
 8. PERFORMING ORGANIZATION REPORT NO. 
 
 9. PERFORMING ORGANIZATION NAME AND ADDRESS 
 
 Technical Support Branch 
 
 Risk Reduction Engineering Laboratory, D.S.E.P.A. 
 
 26 W. Martin Luther King Drive 
 
 Cincinnati, OH 45268 
 
 10 PROGRAM ELEMENT NO. 
 
 Y-109 
 
 11. CONTRACT/GRANT NO 
 
 NA 
 
 12. SPONSORING AGENCY NAME AND ADDRESS 
 
 Risk Reduction Engineering Laboratory—Cin., OH 
 
 Office of Research and Development 
 
 D.S. Environmental Protection Agency 
 
 Cincinnati, OH 45268 
 
 13. TYPE OF REPORT AND PERIOD COVERED 
 
 Bulletin 
 
 14. SPONSORING AGENCY CODE 
 
 EPA/540/2-9/022 
 
 15. supplementary NOTES 
 
 Eugene Harris (513) 569-7862 
 
 16. ABSTRACT 
 
 Solidification refers to techniques that encapsulate hazardous waste 
 into a solid material of high structural integrity. Encapsulation involves 
 either fine waste particles (microencapsulation) or a large block or container 
 of wastes (macroencapsulation). Stabilization refers to techniques that treat 
 hazardous waste by converting it into a less soluble, mobile, or toxic form. 
 Solidification/Stabilization processes utilize one or both of these 
 techniques. 
 
 This bulletin provides information on the technology applicability, the 
 technology limitations, a description of the technology, the types of 
 residuals produced, site requirements, the latest performance data, the status 
 of the technology, and sources of further information. 
 
 17 KEY WORDS AND DOCUMENT ANALYSIS 
 
 a. DESCRIPTORS 
 
 b. 1DENTI F IE R S/OPEN ENDED TERMS 
 
 c. COSati Field/Group 
 
 Stabilization, Solidification, Soil 
 
 Treatment, CERCLA 
 
 
 
 18. DISTRIBUTION STATEMENT 
 
 RELEASE TO PUBLIC 
 
 19 SECURITY CLASS (This Report) 
 
 UNCLASSIFIED 
 
 21. NO. OF PAGES 
 
 10 
 
 20. SECURITY CLASS (This page) 
 
 UNCLASSIFIED 
 
 22 PRICE 
 
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