characterizing waste

Part IGetting Started

Chapter 2 Characterizing Waste

Contents

I. Waste Characterization Through Process Knowledge ..............................................................................2 - 2

II. Waste Characterization Through Leachate Testing ..................................................................................2 - 3

A. Sampling and Analysis Plan ..................................................................................................................2 - 4

1. Representative Waste Sampling..........................................................................................................2 - 6

2. Representative Waste Analysis ..........................................................................................................2 - 8

B. Leachate Test Selection ..........................................................................................................................2 - 9

1. Toxicity Characteristic Leaching Procedure (TCLP) ........................................................................2 - 10

2. Synthetic Precipitation Leaching Procedure (SPLP)..........................................................................2 - 11

3. Multiple Extraction Procedure (MEP) ..............................................................................................2 - 12

4. Shake Extraction of Solid Waste with Water or Neutral Leaching Procedure ..................................2 - 13

III. Waste Characterization of Volatile Organic Emissions ..........................................................................2 - 13

Waste Characterization Activity List ............................................................................................................2 - 15

Resources ....................................................................................................................................................2 - 16

Appendix ....................................................................................................................................................2 - 18

Getting Started—Characterizing Waste

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Understanding the physical andchemical properties of a wasteusing sampling and analysistechniques is the cornerstoneupon which subsequent steps in

the Guide are built. It is necessary for gaugingwhat risks a waste might pose to surface water,ground water, and air and drives waste man-agement unit design and operating decisions.Knowing the composition of the waste is alsonecessary when determining the constituentsfor which to test. And, as discussed in Chapter3–Integrating Pollution Prevention, knowledgeof the physical and chemical properties of thewaste is crucial in identifying pollution pre-vention opportunities.

In many instances, you can use knowledgeof waste generation processes, analytical test-

ing, or some combination of the two to esti-mate waste generation rates and waste con-stituent concentrations. To the extent that thewaste is not highly variable, the use of processknowledge can be a sound approach to wastecharacterization and can prove more reason-able and cost effective than frequent samplingof the waste. It is important to note, however,that owners or operators using process knowl-edge to characterize a waste in lieu of testingare still responsible for the accuracy of theirdeterminations. No matter what approach isused in characterizing a waste, the goal is tomaximize the available knowledge that is nec-essary to make the important decisionsdescribed in later chapters of the Guide. Also,as changes are made to the industrial process-es or waste management practices, it might benecessary to recharacterize a waste in order toaccurately make waste management decisionsand evaluate risk.

In considering the use of process knowl-edge or analytical testing, it is important tonote that the ground water and air emissionsmodels that accompany the Guide use con-stituent concentrations to estimate risk. Inputrequires specific concentrations which cannotbe precisely estimated solely by knowledge ofthe processes that generate the waste. Further,when wastes are placed in a waste manage-ment unit, such as a landfill or surface

Characterizing WasteThis chapter will help you:

• Understand the industrial processes that generate a waste.

• Determine the waste’s physical and chemical properties.

• Estimate constituent leaching to facilitate ground-water risk analysis.

• Quantify total constituent concentrations to facilitate air emissionsanalysis.

This chapter will help you address thefollowing questions:

• How can process knowledge be usedto characterize a waste?

• Which constituent concentrationsshould be quantified?

• Which type of leachate test should beused?

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impoundment, they are subjected to variousphysical, chemical, and biological processesthat can result in the creation of new com-pounds in the waste, changes in the mass andvolume of the waste, and the creation of dif-ferent phases within the waste and within thelandfill or impoundment. In order to accu-rately predict the concentration of the conta-minants in the leachate, these changes mustbe accounted for.

Accurate waste management unit con-stituent characterization is also necessary forinput to the modeling tools provided in theGuide. Because model input requires specificdata, model output will be based on the accu-racy of the data input. Process knowledgealone (unless based on previous testing) mightnot be sufficiently accurate to yield reliableresults. Leachate testing (discussed later inthis chapter), for example, will likely give youa more precise assessment of waste con-stituent concentrations than process knowl-edge. Also note that whether you are usingprocess knowledge, testing, or a combinationof both, sources of model input data must bewell documented so that an individual evalu-ating the modeling results understands thebackground supporting the assessment.

I. WasteCharacterizationThrough ProcessKnowledge

A waste characterization begins with anunderstanding of the industrial processes thatgenerate a waste. You must obtain enoughinformation about the process to enableproper characterization of the waste, forexample, by reviewing process flow diagramsor plans and determining all inputs and out-puts. You should also be familiar with other

waste characteristics such as the physicalstate of the waste, the volume of waste pro-duced, and the general composition of thewaste. In addition, many industries havethoroughly tested and characterized theirwastes over time, therefore it might be benefi-cial to contact your trade association to deter-mine if waste characterizations have alreadybeen performed and are available for process-es similar to yours. Additional resources canassist in waste characterization by providinginformation on waste constituents and poten-tial concentrations. Some examples include:

• Chemical engineering designs orplans for the process, showingprocess input chemicals, expectedprimary and secondary chemicalreactions, and products.

• Material Safety Data Sheets (MSDSs)for materials involved. (Note that notall MSDSs contain information on allconstituents found in a product.)

• Manufacturer’s literature.

• Previous waste analyses.

• Literature on similar processes.

• Preliminary testing results, if available.

A material balance exercise using processknowledge can be useful in understandingwhere wastes are generated within a processand in estimating concentrations of waste con-stituents particularly where analytical test data


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are limited. In a material balance, all inputstreams, such as raw materials fed into theprocesses, and all output streams, such asproducts produced and waste generated, arecalculated. Flow diagrams can be used to iden-tify important process steps and sources wherewastes are generated. Characterizing wastesusing material balances can require consider-able effort and expense, but can help you todevelop a more complete picture of the wastegeneration process(es) involved.

Note that a thorough assessment of yourproduction processes can also serve as thestarting point for facility-wide waste reduc-tion, recycling, or pollution preventionefforts. Such an assessment will provide theinformation base to explore many opportuni-ties to reduce or recycle the volume or toxici-ty of wastes. Refer to Chapter 3–IntegratingPollution Prevention for ideas, tools, and ref-erences on how to proceed.

While the use of process knowledge isattractive because of the cost savings associat-ed with using existing information, you mustensure that this information accurately char-acterizes your wastes. If using processdescriptions, published data, and document-ed studies to determine waste characteristics,the data should be scrutinized carefully todetermine if there are any differences betweenthe processes in the studies and the wastegenerating process at your facility, that thestudies are acceptable and accurate (i.e.,based on valid sampling and analytical tech-niques), and that the information is current.

If there are discrepancies, or if you begin anew process or change any of the existingprocesses at your facility (so that the docu-mented studies and published data are nolonger applicable), you are encouraged toconsider performing additional sampling andlaboratory analysis to accurately characterizethe waste and ensure proper management.Also, if process knowledge is used in addition

to, or in place of, sampling and analysis, youshould clearly document the informationused in your characterization assessment todemonstrate to regulatory agencies, the pub-lic, and other interested parties that the infor-mation accurately and completelycharacterizes the waste. The source of thisinformation should be clearly documented.

II. WasteCharacterizationThroughLeachate Testing

Although sampling and laboratory analysisis not as economical and might not be asconvenient as using process knowledge, itdoes have advantages. The resulting data usu-ally provide the most accurate informationavailable on constituent concentration levels.

What is processknowledge?Process knowledge refers to detailedinformation on processes that generatewastes. It can be used to partly, or inmany cases completely, characterizewaste to ensure proper management.Process knowledge includes:

• Existing published or documentedwaste analysis data or studies con-ducted on wastes generated byprocesses similar to that which gener-ated the waste.

• Waste analysis data obtained fromother facilities in the same industry.

• Facility’s records of previously per-formed analyses.

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Incomplete or mis-characterization of wastecan lead to improper waste management, inac-curate modeling outputs, or erroneous deci-sions concerning the type of unit to be used,liner selection, or choice of land applicationmethods. Note that process knowledge allowsyou to eliminate unnecessary or redundantwaste testing by helping you focus on whichconstituents to measure in the waste. Again,thorough documentation of both the processknowledge used (e.g., studies, published data),as well as the analytical data is important.

The intent of leachate and extraction testingis to estimate the leaching potential of con-stituents of concern to water sources. It isimportant to estimate leaching potential inorder to accurately estimate the quantity ofchemicals that could potentially reach ground-or surface-water resources (e.g., drinkingwater supply wells, waters used for recre-ation). The Industrial Waste ManagementEvaluation Model (IWEM) developed for theGuide uses expected leachate concentrationsfor the waste management units as the basisfor liner system design recommendations.Leachate tests will allow you to accuratelyquantify the input terms for modeling.

If the total concentration of all the con-stituents in a waste has been estimated usingprocess knowledge (which could include pre-vious testing data on wastes known to be verysimilar), estimates of the maximum possibleconcentration of these constituents in leachatecan be made using the dilution ratio of theleachate test to be performed.

For example, the Toxicity CharacteristicLeachate Procedure (TCLP) allows for a totalconstituent analysis in lieu of performing thetest for some wastes. If a waste is 100 percentsolid, as defined by the TCLP method, then

the results of the total compositional analysismay be divided by twenty to convert the totalresults into the maximum leachable concentra-tion1. This factor is derived from the 20:1 liq-uid to solid ratio employed in the TCLP. Thisis a conservative approach to estimatingleachate concentrations and does not factor inenvironmental influences, such as rainfall. If awaste has filterable liquid, then the concentra-tion of each phase (liquid and solid) must bedetermined. The following equation may beused to calculate this value:2

(V1)(C1) + (V2)(C2)

V1 + 20V2

Where:

V1 = Volume of the first phase (L)

C1 = Concentration of the analyte of con-cern in the first phase (mg/L)

V2 = Volume of the second phase (L)

C2 = Concentration of the analyte of con-cern in the second phase (mg/L)

Because this is only a screening method foridentifying an upper-bound TCLP leachateconcentration, you should consult with yourstate or local regulatory agency to determinewhether process knowledge can be used toaccurately estimate maximum risk in lieu ofleachate testing.

A. Sampling and AnalysisPlan

One of the more critical elements in properwaste characterization is the plan for samplingand analyzing the waste. The sampling plan isusually a written document that describes theobjectives and details of the individual tasks of

1 This method is only appropriate for estimating maximum constituent concentration in leachate for non-liquid wastes (e.g., those wastes not discharged to a surface impoundment). For surface impoundments,the influent concentration of heavy metals can be assumed to be the maximum theoretical concentrationof metals in the leachate for purposes of input to the ground-water modeling tool that accompanies thisdocument. To estimate the leachate concentration of organic constituents in liquid wastes for modelinginput, you will need to account for losses occurring within the surface impoundment before you can esti-mate the concentration in the leachate (i.e., an effluent concentration must be determined for organics).

2 Source: Office of Solid Waste Web site at <www.epa.gov/sw-846/sw846.htm>.


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a sampling effort and how they will be per-formed. This plan should be carefully thoughtout, well in advance of sampling. The moredetailed the sampling plan, the less opportu-nity for error or misunderstanding duringsampling, analysis, and data interpretation.

To ensure that the sampling plan isdesigned properly, a wide range of personnelshould be consulted. It is important that thefollowing individuals are involved in thedevelopment of the sampling plan to ensurethat the results of the sampling effort are pre-cise and accurate enough to properly charac-terize the waste:

• An engineer who understands themanufacturing processes.

• An experienced member of the sam-pling team.

• The end user of the data.

• A senior analytical chemist.

• A statistician.

• A quality assurance representative.

It is also advisable that you consult theanalytical laboratory to be used when devel-oping your sampling plan.

Background information on the processesthat generate the waste and the type andcharacteristics of the waste management unitis essential for developing a sound samplingplan. Knowledge of the unit location and sit-uation (e.g., geology, exposure of the waste tothe elements, local climatic conditions) willassist in determining correct sample size andsampling method. Sampling plan design willdepend on whether you are sampling a wasteprior to disposal in a waste management unitor whether you are sampling waste from anexisting unit. When obtaining samples froman existing unit, care should be taken toavoid endangering the individuals collectingthe samples and to prevent damaging the unit

itself. Reasons for obtaining samples from anexisting unit include, characterizing the wastein the unit to determine if the new wastebeing added is compatible, checking to see ifthe composition of the waste is changing overtime due to various chemical and biologicalbreakdown processes, or characterizing thewaste in the unit or the leachate from theunit to give an indication of expected concen-trations in leachate from a new unit.

The sampling plan must be correctlydefined and organized in order to get anaccurate estimation of the characteristics ofthe waste. Both an appropriate sample sizeand proper sampling techniques are neces-sary. If the sampling process is carried outcorrectly, the sample will be representativeand the estimates it generates will be usefulfor making decisions concerning proper man-agement of the waste and for assessing risk.

In developing a sampling plan, accuracy isof primary concern. The goal of sampling is toget an accurate estimate of the waste’s charac-teristics from measuring the sample’s charac-teristics. The main controlling factor indeciding whether the estimates will be accu-rate is how representative the sample is (dis-cussed in the following section). Using a smallsample increases the possibility that the sam-ple will not be representative, but a samplethat is larger than the minimum calculatedsample size does not necessarily increase theprobability of getting a representative sample.

As you are developing the sampling plan, youshould address the following considerations:

• Data quality objectives.

• Determination of a representativesample.

• Statistical methods to be employed inthe analyses.

• Waste generation and handlingprocesses.

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• Constituents/parameters to be sampled.

• Physical and chemical properties ofthe waste.

• Accessibility of the unit.

• Sampling equipment, methods, andsample containers.

• Quality assurance and quality control(e.g., sample preservation and han-dling requirements).

• Chain-of-custody.

• Health and safety of employees.

Many of these considerations are discussedbelow. Additional information on data qualityobjectives and quality assurance and qualitycontrol can be found in Test Methods forEvaluating Solid Waste, Physical/ChemicalMethods—SW-846 (U.S. EPA, 1996e), Guidancefor the Data Quality Objectives Process (U.S.EPA, 1996b), Guidance on Quality AssuranceProject Plans (U.S. EPA, 1998a), and Guidancefor the Data Quality Assessment: PracticalMethods for Data Analysis (U.S. EPA, 1996a).3

A determination as to the constituents thatwill be measured can be based on processknowledge to narrow the focus and expenseof performing the analyses. Analyses shouldbe performed for those constituents that arereasonably expected to be in the waste atdetectable levels (i.e., test method detectionlevels). Note that the Industrial WasteManagement Evaluation Model (IWEM) thataccompanies this document recommendsliner system designs, if necessary, or theappropriateness of land application based oncalculated protective leachate thresholds(Leachate Concentration Threshold Values orLCTVs) for various constituents that are like-ly to be found in industrial waste and posehazards at certain levels to people and theenvironment. The constituents that are evalu-ated are listed in Table 1.2 of the IndustrialWaste Management Evaluation Model Technical

Background Document (U.S. EPA 2002). TheLCTV tables also are included in the IWEMTechnical Background Document and the modelon the CD-ROM version of this Guide, andcan be used as a starting point to help youdetermine which constituents to measure. Itis not recommended that you sample for allof the organic chemicals and metals listed inthe tables, but rather use these tables as aguide in conjunction with knowledge con-cerning the waste generating practices todetermine which constituents to measure.

1. Representative WasteSampling

The first step in any analytical testingprocess is to obtain a sample that is represen-tative of the physical and chemical composi-tion of a waste. The term “representativesample” is commonly used to denote a samplethat has the same properties and compositionin the same proportions as the populationfrom which it was collected. Finding one sam-ple which is representative of the entire wastecan be difficult unless you are dealing with ahomogenous waste. Because most industrialwastes are not homogeneous, many differentfactors should be considered in obtainingsamples. Examples of some of the factors thatshould be considered include:

• Physical state of the waste. Thephysical state of the waste affectsmost aspects of a sampling effort. Thesampling device will vary accordingto whether the sample is liquid, solid,gas, or multiphasic. It will also varyaccording to whether the liquid isviscous or free-flowing, or whetherthe solid is hard, soft, powdery,monolithic, or clay-like.

• Composition of the waste. Thesamples should represent the averageconcentration and variability of thewaste in time or over space.

3 These and other EPA publications can be found at the National Environmental Publications Internetsite (NEPIS) at <www.epa.gov/ncepihom/nepishom/>.


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• Waste generation and han-dling processes. Processes toconsider include: if the wasteis generated in batches; ifthere is a change in the rawmaterials used in a manufac-turing process; if waste com-position can vary substantiallyas a function of process tem-peratures or pressures; and ifstorage time affects the waste’scharacteristics/composition.

• Transitory events. Start-up,shut-down, slow-down, andmaintenance transients canresult in the generation of awaste that is not representativeof the normal waste stream. Ifa sample was unknowinglycollected at one of these inter-vals, incorrect conclusionscould be drawn.

You should consult with your state orlocal regulatory agency to identify anylegal requirements or preferences beforeinitiating sampling efforts. Refer toChapter 9 of the EPA’s SW-846 testmethods document (see side bar) fordetailed guidance on planning, imple-menting, and assessing sampling events.

To ensure that the chemical infor-mation obtained from waste samplingefforts is accurate, it must be unbiasedand sufficiently precise. Accuracy isusually achieved by incorporatingsome form of randomness into thesample selection process and by select-ing an appropriate number of samples.Since most industrial wastes are het-erogeneous in terms of their chemicalproperties, unbiased samples andappropriate precision can usually beachieved by simple random sampling.In this type of sampling, all units inthe population (essentially all locations

More information on Test Methodsfor Evaluating Solid Waste, Physical/Chemical Methods—SW-846

EPA has begun replacing requirements mandat-ing the use of specific measurement methods ortechnologies with a performance-based measure-ment system (PBMS). The goal of PBMS is toreduce regulatory burden and foster the use ofinnovative and emerging technologies or meth-ods. The PBMS establishes what needs to beaccomplished, but does not prescribe specificallyhow to do it. In a sampling situation, for exam-ple, PBMS would establish the data needs, thelevel of uncertainty acceptable for making deci-sions, and the required supporting documenta-tion; a specific test method would not beprescribed. This approach allows the analyst theflexibility to select the most appropriate and costeffective test methods or technologies to complywith the criteria. Under PBMS, the analyst isrequired to demonstrate the accuracy of the mea-surement method using the specific matrix that isbeing analyzed. SW-846 serves only as a guidancedocument and starting point for determiningwhich test method to use.

SW-846 provides state-of-the-art analytical testmethods for a wide array of inorganic and organicconstituents, as well as procedures for field andlaboratory quality control, sampling, and charac-teristics testing. The methods are intended to pro-mote accuracy, sensitivity, specificity, precision,and comparability of analyses and test results.

For assistance with the methods described in SW-846, call the EPA Method InformationCommunication Exchange (MICE) Hotline at 703676-4690 or send an e-mail to [email protected].

The text of SW-846 is available online at:<www.epa.gov/sw-846/main.htm>. A hard copyor CD-ROM version of SW-846 can be purchasedby calling the National Technical InformationService (NTIS) at 800 553-6847.

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or points in all batches of waste from which asample could be collected) are identified, anda suitable number of samples is randomlyselected from the population.

The appropriate number of samples toemploy in a waste characterization is at leastthe minimum number of samples required togenerate a precise estimate of the true meanconcentration of a chemical contaminant in awaste. A number of mathematical formulasexist for determining the appropriate numberof samples depending on the statistical preci-sion required. Further information on sam-pling designs and methods for calculatingrequired sample sizes and optimal distribu-tion of samples can be found in Gilbert(1987), Winer (1971), and Cochran (1977)and Chapter 9 of EPA SW-846.

The type of sampling plan developed willvary depending on the sampling location.Solid wastes contained in a landfill or wastepile can be best sampled using a three-dimensional random sampling strategy. Thisinvolves establishing an imaginary three-dimensional grid or sampling points in thewaste and then using random-number tablesor random-number generators to select pointsfor sampling. Hollow-stem augers combinedwith split-spoon samplers are frequentlyappropriate for sampling landfills.

If the distribution of waste components isknown or assumed for liquid or semi-solidwastes in surface impoundments, then a two-dimensional simple random sampling strategymight be appropriate. In this strategy, the topsurface of the waste is divided into an imagi-nary grid and grid sections are selected usingrandom-number tables or random-numbergenerators. Each selected grid point is thensampled in a vertical manner along the entirelength from top to bottom using a samplingdevice such as a weighted bottle, a drumthief, or Coliwasa.

If sampling is restricted, the sampling strat-egy should, at a minimum, take sufficientsamples to address the potential vertical varia-tions in the waste in order to be consideredrepresentative. This is because containedwastes tend to display vertical, rather thanhorizontal, non-random heterogeneity due tosettling or the layering of solids and denserliquid phases. Also, care should be takenwhen performing representative sampling of alandfill, waste pile, or surface impoundmentto minimize any potential to create hazardousconditions. (It is possible that the improperuse of intrusive sampling techniques, such asthe use of augers, could accelerate leaching bycreating pathways or tunnels that can acceler-ate leachate movement to ground water.)

To facilitate characterization efforts, consultwith state and local regulatory agencies and aqualified professional to select a sampling planand determine the appropriate number of sam-ples, before beginning sampling efforts. Youshould also consider conducting a detailedwaste-stream specific characterization so thatthe information can be used to conduct wastereduction and waste minimization activities.

Additional information concerning sam-pling plans, strategies, methods, equipment,and sampling quality assurance and qualitycontrol is available in Chapters 9 and 10 of theSW-846 test methods document. Electronicversions of these chapters have been includedon the CD-ROM version of the Guide.

2. Representative Waste AnalysisAfter a representative sample has been col-

lected, it must be properly preserved to main-tain the physical and chemical properties thatit possessed at the time of collection. Sampletypes, sample containers, container prepara-tion, and sample preservation methods arecritical for maintaining the integrity of thesample and obtaining accurate results.Preservation and holding times are also


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4 There are several general categories of phases in which samples can be categorized: solids, aqueous,sludges, multiphase samples, ground water, and oil and organic liquid. You should select a test that isdesigned for the specific sample type.

important factors to consider and will varydepending on the type of constituents beingmeasured (e.g., VOCs, heavy metals, hydro-carbons) and the waste matrix (e.g., solid,liquid, semi-solid).

The analytical chemist then develops ananalytical plan which is appropriate for thesample to be analyzed, the constituents to beanalyzed, and the end use of the informationrequired. The laboratory should have standardoperating procedures available for review forthe various types of analyses to be performedand for all associated methods needed to com-plete each analysis, such as instrument main-tenance procedures, sample handlingprocedures, and sample documentation proce-dures. In addition, the laboratory should havea laboratory quality assurance/quality controlstatement available for review which includesall key personnel qualifications.

The SW-846 document contains informa-tion on analytical plans and methods.Another useful source of information regard-ing the selection of analytical methods andquality assurance/quality control proceduresfor various compounds is the Office of SolidWaste Methods Team home page at<www.epa.gov/sw-846/index.htm>.

B. Leachate Test SelectionLeaching tests are used to estimate poten-

tial concentration or amount of waste con-stituents that can leach from a waste toground water. Typical leaching tests use aspecified leaching fluid mixed with the solidportion of a waste for a specified time. Solidsare then separated from the leaching solutionand the solution is tested for waste con-stituent concentrations. The type of leachingtest performed can vary depending on thechemical, biological, and physical characteris-tics of the waste; the environment in whichthe waste will be placed; as well as the rec-

ommendations or requirements of your stateand local regulatory agencies.

When selecting the most appropriate ana-lytical tests, consider at a minimum the phys-ical state of the sample, the constituents to beanalyzed, detection limits, and the specifiedholding times of the analytical methods.4 Itmight not be cost-effective or useful to con-duct a test with detection limits at or greaterthan the constituent concentrations in awaste. Process knowledge can help you pre-dict whether the concentrations of certainconstituents are likely to fall below the detec-tion limits for anticipated methods.

After assessing the state of the waste, assessthe environment of the waste managementunit in which the waste will be placed. Forexample, an acidic environment mightrequire a different test than a non-acidic envi-ronment in order to best reflect the condi-tions under which the waste will actuallyleach. If the waste management unit is amonofill, then the characteristics of the wastewill determine most of the unit’s conditions.Conversely, if many different wastes are beingco-disposed, then the conditions created by

Which leaching test isappropriate?

Selecting an appropriate leachate testcan be summarized in the following foursteps:

1. Assess the physical state of the wasteusing process knowledge.

2. Assess the environment in which thewaste will be placed.

3. Consult with your state and/or localregulatory agency.

4. Select an appropriate leachate testbased on the above information.

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5 EPA has only reviewed and evaluated those test methods found in SW-846. The EPA has not reviewedor evaluated the other test methods and cannot recommend use of any test methods other than thosefound in SW-846.

6 EPA is undertaking a review of the TCLP test and how it is used to evaluate waste leaching (describedin the Phase IV Land Disposal Restrictions rulemaking, 62 Federal Register 25997; May 26, 1998). EPAanticipates that this review will examine the effects of a number of factors on leaching and onapproaches to estimating the likely leaching of a waste in the environment. These factors include pH,liquid to solid ratios, matrix effects and physical form of the waste, effects of non-hazardous salts onthe leachability of hazardous metal salts, and others. The effects of these factors on leaching might ormight not be well reflected in the leaching tests currently available. At the conclusion of the TCLPreview, EPA is likely to issue revisions to this guidance that reflect a more complete understanding ofwaste constituent leaching under a variety of management conditions.

7 The TCLP was developed to replace the Extraction Procedure Toxicity Test method which is designatedas EPA Method 1310 in SW-846.


the co-disposed wastes must be considered,including the constituents that can be leachedby the subject waste.

A qualified laboratory should always be usedwhen conducting analytical testing. The labora-tory can be in-house or independent. Whenusing independent laboratories, ensure thatthey are qualified and competent to performthe required tests. Some laboratories might beproficient in one test but not another. Youshould consult with the laboratory before final-izing your test selection to make certain thatthe test can be performed. When using analyti-cal tests that are not frequently performed,additional quality assurance and quality controlpractices might need to be implemented toensure that the tests are conducted correctlyand that the results are accurate.

A brief summary of the TCLP and threeother commonly used leachate tests is provid-ed below (procedures for the EPA test meth-ods are included in SW-846 and for theASTM method in the Annual Book of ASTMStandards). These summaries are provided asbackground and are not meant to imply thatthese are the only tests that can be used toaccurately predict leachate potential. Otherleachate tests have been developed and mightbe suitable for testing your waste. The tablein the appendix at the end of this chapterprovides a summary of over 20 leachate teststhat have been designed to estimate thepotential for contaminant release, includingseveral developed by ASTM.5 You should con-

sult with state and local regulatory agenciesand/or a laboratory that is familiar withleachate testing methods to identify the mostappropriate test and test method proceduresfor your waste and sample type.

1. Toxicity Characteristic LeachingProcedure (TCLP)

The TCLP 6 is the test method used to deter-mine whether a waste is hazardous due to itscharacteristics as defined in the ResourceConservation and Recovery Act (RCRA), 40CFR Part 261. The TCLP estimates the leacha-bility of certain toxicity characteristic hazardousconstituents from solid waste under a definedset of laboratory conditions. It evaluates theleaching of metals, volatile and semi-volatileorganic compounds, and pesticides fromwastes. The TCLP was developed to simulatethe leaching of constituents into ground waterunder conditions found in municipal solidwaste (MSW) landfills. The TCLP does not sim-ulate the release of contaminants to non-groundwater pathways. The TCLP is most commonlyused by EPA, state, and local agencies to classifywaste. It is also used to determine compliancewith some land disposal restrictions (LDRs) forhazardous wastes. The TCLP can be found asEPA Method 1311 in SW-846.7 A copy ofMethod 1311 has been included on the CD-ROM version of the Guide.

For liquid wastes, (i.e., those containingless than 0.5 percent dry solid material) thewaste after filtration through a glass fiber fil-

ter is defined as the TCLP extractant. Theconcentrations of constituents in the liquidextract are then determined.

For wastes containing greater than or equalto 0.5 percent solids, the liquid, if any, is sep-arated from the solid phase and stored forlater analysis. The solids must then bereduced to particle size, if necessary. Thesolids are extracted with an acetate buffersolution. A liquid-to-solid ratio of 20:1 byweight is used for an extraction period of 18± 2 hours. After extraction, the solids are fil-tered from the liquid through a glass fiber fil-ter and the liquid extract is combined withany original liquid fraction of the wastes.Analyses are then conducted on the liquid fil-trate/leachate to determine the constituentconcentrations.

To determine if a waste is hazardousbecause it exhibits the toxicity characteristic(TC), the TCLP method is used to generateleachate under controlled conditions as dis-cussed above. If the TCLP liquid extract con-tains any of the constituents listed in Table 1of 40 CFR Part 261 at a concentration equalto or greater than the respective value in thetable, the waste is considered to be a TC haz-ardous waste, unless exempted or excludedunder Part 261. Although the TCLP test wasdesigned to determine if a waste is hazardous,the importance of its use for waste characteri-zation as discussed in this chapter is tounderstand the parameters to be consideredin properly managing the wastes.

You should check with state and local reg-ulatory agencies to determine whether theTCLP is likely to be the best test for evaluat-ing the leaching potential of a waste or ifanother test might better predict leachingunder the anticipated waste managementconditions. Because the test was developed byEPA to determine if a waste is hazardous(according to 40 CFR 261.24) and focusedon simulating leaching of solid wastes placed

in a municipal landfill, this test might not beappropriate for your waste because the leach-ing potential for the same chemical can bequite different depending on a number of fac-tors. These factors include the characteristicsof the leaching fluid, the form of the chemicalin the solids, the waste matrix, and the dis-posal conditions.

Although the TCLP is the most commonlyused leachate test for estimating the actualleaching potential of wastes, you should notautomatically default to it in all situations orconditions and for all types of wastes. Whilethe TCLP test might be conservative undersome conditions (i.e., overestimates leachingpotential), it might underestimate leachingunder other extreme conditions. In a landfillthat has primarily alkaline conditions, theTCLP is not likely to be the optimal methodbecause the TCLP is designed to replicateleaching in an acidic environment. For mate-rials that pose their greatest hazard whenexposed to alkaline conditions (e.g., metalssuch as arsenic and antimony), use of theTCLP might underestimate the leachingpotential. When the conditions of your wastemanagement unit are very different from theconditions that the TCLP test simulates,another test might be more appropriate.Further, the TCLP might not be appropriatefor analyzing oily wastes. Oil phases can bedifficult to separate (e.g., it might be impossi-ble to separate solids from oil), oily materialcan obstruct the filter (often resulting in anunderestimation of constituents in theleachate), and oily materials can yield bothoil and aqueous leachate which must be ana-lyzed separately.8

2. Synthetic PrecipitationLeaching Procedure (SPLP)

The SPLP (designated as EPA Method 1312in SW-846) is currently used by several stateagencies to evaluate the leaching of con-


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8 SW-846 specifies several procedures that should be followed when analyzing oily wastes.

stituents from wastes. The SPLP was designedto estimate the leachability of both organicand inorganic analytes present in liquids, soils,and wastes. The SPLP was originally designedto assess how clean a soil was under EPA’sClean Closure Program. Even though the fed-eral hazardous waste program, did not adoptit for use, the test can still estimate releasesfrom wastes placed in a landfill and subject toacid rain. There might be, however, importantdifferences between soil as a constituentmatrix (for which the SPLP is primarily used)and the matrix of a generated industrial waste.A copy of Method 1312 has been included onthe CD-ROM version of the Guide.

The SPLP is very similar to the TCLPMethod 1311. Waste samples containingsolids and liquids are handled by separatingthe liquids from the solid phase, and thenreducing solids to particle size. The solids arethen extracted with a dilute sulfuricacid/nitric acid solution. A liquid-to-solidratio of 20:1 by weight is used for an extrac-tion period of 18±2 hours. After extraction,the solids are filtered from the liquid extractand the liquid extract is combined with anyoriginal liquid fraction of the wastes.Analyses are then conducted on the liquid fil-trate/leachate to determine the constituentconcentrations.

The sulfuric acid/nitric acid extractionsolution used in the SPLP was selected tosimulate leachate generation, in part, fromacid rain. Also note that in both the SPLP

and TCLP, some paint and oily wastes mightclog the filters used to separate the liquidextract from the solids prior to analysis,resulting in under reporting of the extractableconstituent concentrations.

3. Multiple Extraction Procedure(MEP)

The MEP (designated as EPA Method 1320in SW-846) was designed to simulate theleaching that a waste will undergo from repeti-tive precipitation of acid rain on a landfill todetermine the highest concentration of eachconstituent that is likely to leach in a realworld environment. Currently, the MEP is usedin EPA’s hazardous waste delisting program. Acopy of Method 1320 has been included onthe CD-ROM version of the Guide.

The MEP can be used to evaluate liquid,solid, and multiphase samples. Waste sam-ples are extracted according to the ExtractionProcedure (EP) Toxicity Test (Method 1310of SW-846). The EP test is also very similarto the TCLP Method 1311. A copy of Method1310 has been included on the CD- ROMversion of the Guide.

In the MEP, liquid wastes are filteredthrough a glass fiber filter prior to testing.Waste samples containing both solids and liq-uids are handled by separating the liquidsfrom the solid phase, and then reducing thesolids to particle size. The solids are thenextracted using an acetic acid solution. A liq-uid- to-solid ratio of 16:1 by weight is usedfor an extraction period of 24 hours. Afterextraction, the solids are filtered from the liq-uid extract, and the liquid extract is combinedwith any original liquid fraction of the waste.

The solids portion of the sample thatremains after application of Method 1310 arethen re-extracted using a dilute sulfuricacid/nitric acid solution. As in the SPLP, thisacidic solution was selected to simulate

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leachate generation, in part, from acid rain.This time a liquid-to-solid ratio of 20:1 byweight is used for an extraction period of 24hours. After extraction, the solids are onceagain filtered from the liquid extract, and theliquid extract is combined with any originalliquid fraction of the waste.

These four steps are repeated eight addi-tional times. If the concentration of any con-stituent of concern increases from the 7th or8th extraction to the 9th extraction, the pro-cedure is repeated until these concentrationsdecrease.

The MEP is intended to simulate 1,000years of freeze and thaw cycles and prolongedexposure to a leaching medium. One advan-tage of the MEP over the TCLP is that theMEP gradually removes excess alkalinity inthe waste. Thus, the leaching behavior ofmetal contaminants can be evaluated as afunction of decreasing pH, which increasesthe solubility of most metals.

4. Shake Extraction of SolidWaste with Water or NeutralLeaching Procedure

The Shake Extraction of Solid Waste withWater, or the Neutral Leaching Procedure,was developed by the American Society forTesting and Materials (ASTM) to assess theleaching potential of solid waste and has beendesignated as ASTM D-3987-85. This testmethod provides for the shaking of an extrac-tant (e.g., water) and a known weight ofwaste of specified composition to obtain anaqueous phase for analysis after separation.The intent of this test method is for the finalpH of the extract to reflect the interaction ofthe liquid extractant with the buffering capac-ity of the solid waste.

The shake test is performed by mixing thesolid sample with test water and agitatingcontinuously for 18±0.25 hours. A liquid-to-

solid ratio of 20:1 by weight is used. Afteragitation the solids are filtered from the liquidextract, and the liquid is analyzed.

The water extraction is meant to simulateconditions where the solid waste is the domi-nant factor in determining the pH of theextract. This test, however, has only beenapproved for certain inorganic constituents,and is not applicable to organic substancesand volatile organic compounds (VOCs). Acopy of this procedure can be ordered bycalling ASTM at 610 832-9585 or online at<www.astm.org>.

III. WasteCharacterizationof VolatileOrganicEmissions

To determine whether volatile organicemissions are of concern at a waste manage-ment unit, determine the concentration of theVOCs that are reasonably expected to beemitted. Process knowledge is likely to beless accurate for determining VOCs thanmeasured values. As discussed earlier in thischapter, modeling results for waste manage-ment units will only be as accurate as theinput data. Therefore, sampling and analyticaltesting might be necessary if organic concen-trations cannot be estimated confidentlyusing process knowledge.

Table 2 in Chapter 5–Protecting Air Qualitycan be used as a starting point to help youdetermine which air emissions constituents tomeasure. It is not recommended that yousample for all of the volatile organics listed inTable 2, but rather use Table 2 as a guide inconjunction with process knowledge to nar-row the sampling effort and thereby minimize


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unnecessary sampling costs. A thoroughunderstanding of process knowledge can helpyou determine what is reasonably expected tobe in the waste, so that it is not necessary tosample for unspecified constituents.

Many tests have been developed for quan-titatively extracting volatile and semi-volatileorganic constituents from various samplematrices. These tests tend to be highlydependent upon the physical characteristicsof the sample. You should consult with stateand local regulatory agencies before imple-menting testing. You can refer to SW-846Method 3500B for guidance on the selectionof methods for quantitative extraction ordilution of samples for analysis by one of thevolatile or semi-volatile determinative meth-ods. After performing the appropriate extrac-tion procedure, further cleanup of the sampleextract might be necessary if analysis of theextract is prevented due to interferencescoextracted from the sample. Method 3600of SW-846 provides additional guidance oncleanup procedures.

Following sample preparation, a sample isready for further analysis. Most analyticalmethods use either gas chromatography(GC), high performance liquid chromatogra-phy (HPLC), gas chromatography/mass spec-trometry (GC/MS), or high performanceliquid chromatography/mass spectrometry(HPLC/MS). SW-846 is designed to allow themethods to be mixed and matched, so thatsample preparation, sample cleanup, andanalytical methods can be properlysequenced for the particular analyte andmatrix. Again, you should consult with stateand local regulatory agencies before finalizingthe selected methodology.

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To determine constituent concentrations in a waste you should:

■■■■ Assess the physical state of the waste using process knowledge.

■■■■ Use process knowledge to identify constituents for further analysis.

■■■■ Assess the environment in which the waste will be placed.

■■■■ Consult with state and local regulatory agencies to determine any specific testing requirements.

■■■■ Select an appropriate leachate test or organic constituent analysis based on the above information.

Waste Characterization Activity List

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ASTM. 1995. Annual Book of ASTM Standards.

ASTM. Standard Methods for Examination of Water and Wastewater.

ASTM. D-3987-85. Standard Test Method for Shake Extraction of Solid Waste with Water

California EPA. Handbook for the Analysis and Classification of Wastes.

California EPA. 1995. Preliminary Proposal to Require the TCLP in Lieu of the Waste ExtractionTest. Memorandum to James Carlisle, Department of Toxics Substances Control, from JonMarshack, California Regional Water Quality Control Board. December 18.

California EPA. 1994. Regulation Guidance: When Extraction Tests are Not Necessary.

California EPA. 1994. Regulation Guidance: TCLP vs. WET.

California EPA. 1993. Regulation Guidance: Lab Methods.

California EPA. 1993. Regulation Guidance: Self-Classification.

Cochran, W.G. 1977. Sampling Techniques. Third Edition. New York: John Wiley and Sons.

Dusing, D.C., Bishop, P.L., and Keener, T.C. 1992. Effect of Redox Potential on Leaching fromStabilized/Solidified Waste Materials. Journal of Air and Waste Management Association. 42:56.January.

Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. New York: VanNostrand Reinhold Company.

Kendall, Douglas. 1996. Impermanence of Iron Treatment of Lead-Contaminated Foundry Sand—NIBCO, Inc., Nacogdoches, Texas. National Enforcement Investigations Center Project PA9. April.

Kosson, D.S., H.A. van der Sloot, F. Sanchez, and A.C. Garrabrants. 2002. An IntegratedFramework for Evaluating Leaching in Waste Management and Utilization of Secondary Materials.Environmental Engineering Science, In-press.

New Jersey Department of Environmental Protection. 1996. Industrial Pollution Prevention Trendsin New Jersey.

Resources


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Northwestern University. 1995. Chapter 4—Evaluation of Procedures for Analysis and Disposal ofLead- Based Paint-Removal Debris. Issues Impacting Bridge Painting: An Overview. InfrastructureTechnology Institute. FHWA/RD/94/098. August.

U.S. EPA 2002. Industrial Waste Managment Evaluation (IWEM) Technical Background Document.EPA530-R-02-012.

U.S. EPA. 1998a. Guidance on Quality Assurance Project Plans: EPA QA/G-5. EPA600-R-98-018.

U.S. EPA. 1998b. Guidance on Sampling Designs to Support QA Project Plans. QA/G-5S

U.S. EPA. 1997. Extraction Tests. Draft.

U.S. EPA. 1996a. Guidance for the Data Quality Assessment: Practical Methods for Data Analysis:EPAQA/G-9. EPA600-R-96-084.

U.S. EPA. 1996b. Guidance for the Data Quality Objectives Process: EPA QA/G-4. EPA600-R-96-055.

U.S. EPA. 1996c. Hazardous Waste Characteristics Scoping Study.

U.S. EPA. 1996d. National Exposure Research Laboratory (NERL)-Las Vegas: Site CharacterizationLibrary, Volume 2.

U.S. EPA. 1996e. Test Methods for Evaluating Solid Waste Physical/Chemical Methods—SW846. ThirdEdition.

U.S. EPA. 1995. State Requirements for Non-Hazardous Industrial Waste Management Facilities.

U.S. EPA. 1993. Identifying Higher-Risk Wastestreams in the Industrial D Universe: The StateExperience. Draft.

U.S. EPA. 1992. Facility Pollution Prevention Guide. EPA600-R-92-088.

U.S. EPA Science Advisory Board. 1991. Leachability Phenomena: Recommendations and Rationale forAnalysis of Contaminant Release by the Environmental Engineering Committee. EPA-SAB-EEC-92-003.

Winer, B.J. 1971. Statistical Principles in Experimental Design. New York: McGraw-Hill.

Resources (cont.)

Test Method Leaching Fluid Liquid:Solid Maximum Number of Time of CommentsRatio Particle Size Extractions Extractions

I. Static Tests

A. Agitated Extraction Tests

Toxicity 0.1 N acetic acid solution, 20:1 9.5 mm 1 18 ±2 hours Co-disposal scenario might Characteristic pH 2.9, for alkaline wastes not be appropriate; no Leaching 0.1 N sodium acetate allowance for structural Procedure (1311) buffer solution, pH 5.0, integrity testing of

for non-alkaline wastes monolithic samples

Extraction 0.5 N acetic acid (pH-5.0) 16:1 during 9.5 mm 1 24 hours High alkalinity samples can Procedure extraction result in variable dataToxicity Test (1310) 20:1 final

dilution

ASTM D3987-85 ASTM IV reagent water 20:1 As in 1 18 hours Not validated for organicsShake Extraction environment of Solid Waste (as received)with Water

California WET 0.2 M sodium citrate 10:1 2.0 mm 1 48 hours Similar to EP, but sodium(pH- 5.0) citrate makes test more

aggressive

Ultrasonic Distilled water 4:1 Ground 1 30 minutes New—little performance Agitation dataMethod for Accelerating Batch Leaching Test9

Alternative TCLP TCLP acetic acid solutions 20:1 <9.5 1 8 hours Uses heat to decrease for Construction, extraction timeDemolition and Lead Paint Abatement Debris10

Extraction Soxhlet with THF and 100g:300mL 9.5 mm 3 24 hours (EP)Procedure for Oily toluene EP on remaining 20:1Waste (1330) solids

Synthetic #1 Reagent water to pH 4.2 20:1 9.5 mm 1 18±2 hours ZHE option for organicsPrecipitation with nitric and sulfuric Leaching Procedure acids (60/40) (1312) #2 Regent water to pH 5.0

with nitric and sulfuric acids (60/40)

Equilibrium Leach Distilled water 4:1 150 mm 1 7 days Determines contaminants Test that have been insolubilized

by solidification

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9 Bisson, D.L.; Jackson D.R.; Williams K.R.; and Grube W.E. J. Air Waste Manage. Assoc., 41: 1348-1354.

10 Olcrest, R. A Representative Sampling and Alternative Analytical Toxic Characteristic Leachate ProcedureMethod for Construction, Demolition, and Lead Paint Abatement Debris Suspected of Containing LeachableLead, Appl. Occup. Environ. Hyg. 11(1), January 1996.

Appendix: Example Extraction Tests (Draft 9/30/97)

B. Non-Agitated Extraction Tests

Static Leach Test Can be site specific, 3 VOL/surface 40 mm2 1 >7 days Series of optional steps Method (material standard leachates: water, 10 cm surface area increasing complexity of characteristic brine, silicate/bicarbonate analysiscentre- 1)

High Temperature Same as MCC-1 (conducted VOL/Surface 40 mm2 1 >7 Days Series of optional steps Static Leach Tests at 100°C) 10 cm Surface Area increasing complexity of Method (material analysischaracterization centre-2)

C. Sequential Chemical Extraction Tests

Sequential 0.04 m acetic acid 50:1 9.5 mm 15 24 hours per Extraction Tests extraction

D. Concentration Build-Up Test

Sequential 5 leaching solutions of Varies from 150 mm 5 Varies 3 or Examines partitioning of Chemical increasing acidity 16.1 to 40.1 14 days metals into different Extraction fractions or chemicals forms

Standard Leach DI water SYN Landfill 10:1, 5:1, As in 3 3 or 14 days Sample discarded after each Test, Procedure C 7.5:1 environment leach, new sample added to (Wisconsin) existing leachate

II. Dynamic Tests (Leaching Fluid Renewed)

A. Serial Batch (Particle)

Multiple Extraction Same as EP TOX, then 20:1 9.5 mm 9 (or more) 24 hours perProcedure (1320) with synthetic acid rain extraction

(sulfuric acid, nitric acid in 60:40% mixture)

Monofill Waste Distilled/deionized water 10:1 per 9.5 mm or 4 18 hours perExtraction or other for specific site extraction monolith extractionProcedures

Graded Serial Batch Distilled water Increases N/A >7 Until steady (U.S. Army) from 2:1 to state

96:1

Sequential Batch Type IV reagent water 20:1 As in 10 18 hoursExt. of Waste with environmentWater ASTM D-4793-93


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Use of Chelating Demineralized water with 50 or 100 <300 µm 1 18, 24, or Experimental test based on Agent to Determine EDTA, sample to a final 48 hours Method 7341the Metal pH of 7±0.5Availability for Leaching Soils and Wastes11

B. Flow Around Tests

IAEA Dynamic DI water/site water N/A One face >19 >6 monthsLeach Test prepared(International Atomic Energy Agency)

Leaching Tests on 0.1N acetic acid 20:1 0.6 µm-70µm 1 24 hours S/S technologies most valid Solidified Products12 (Procedure A) when applied to wastes

2:1 (6 hrs.) contaminated by inorganic & 10:1 pollutants(18 hrs.) (Procedure B)

DLT DI water N/A Surface 18 196 dayswashing

C. Flow Through Tests

ASTM D4874-95 Type IV reagent water One void 10 mm 1 24 hoursColumn Test volume

III. Other Tests

MCC-5s Soxhlet DI/site water 100:1 Out and 1 0.2 ml/minTest (material washedcharacteristic center)

ASTM C1308-95 Only applicable if diffusion Accelerated Leach is dominant leaching Test13 mechanism

Generalized Acid Acetic acid 20:1 Able to pass 1 48 hours Quantifies the alkalinity of Neutralization through an binder and characterizes Capacity Test14 ASTM No. 40 buffering chemistry

sieve

Acid Neutralization HNO3, solutions of 3:1 150 mm 1 48 hours per Capacity increasing strength extraction

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11 Garrabrants, A.C. and Koson, D.S.; Use of Chelating Agent to Determine the Metal Availability for Leachingfrom Soils and Wastes, unpublished.

12 Leaching Tests on Solidified Products; Gavasci, R., Lombardi, F., Polettine, A., and Sirini, P.

13 C1308-95 Accelerated Leach Test for Diffusive Releases from Solidified Waste and a Computer Program toModel Diffusive, Fractional Leaching from Cylindrical Wastes.

14 Generalized Acid Neutralization capacity Test; Isenburg, J. and Moore, M.



characterizing waste

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