Designation:D4874–95(Reapproved2001)
Standard Test Method for
Leaching Solid Material in a Column Apparatus1
This standard is issued under thefixed designation D4874;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.
1.Scope
1.1This test method is a standard laboratory procedure for generating aqueous leachate from materials using a column apparatus.It provides a leachate suitable for organic analysis of semivolatile and nonvolatile compounds as well as inorganic analyses.
1.2The column apparatus is designed and constructed of materials chosen to enhance the leaching of low concentrations of semivolatile and nonvolatile organic constituents as well as to maximize the leaching of metallic species from the solid. Analysis of column effluent provides information on the leaching characteristics of material under the conditions used in the test.
1.3This test method provides for the passage of an aqueous fluid through materials of known mass in a saturated up-flow mode.
1.4It is intended that the sample used in the procedure be physically,chemically,and biologically representative of the material.
1.5This test method does not produce results that can be used as the sole basis for(1)engineering design of a disposal site,or(2)the characterization of wastes based on their leaching characteristics.
1.6This test method has the following limitations:
1.6.1Maximum particle size is10mm(0.4in.).Particle size reduction is not recommended.Large-diameter material(cin-ders,rocks,and so forth)should be removed prior to packing the column to ensure adequate compaction.
1.6.2Test materials containing densely immiscible organic material may result in phase separation and lead to column plugging.
1.6.3This test method does not differentiate between dis-solved constituents and sub-70-µm particulates that pass through the pores of the end plates.
1.6.4This test method is not applicable to the leachability characterization of materials with regard to volatile com-pounds.
1.6.5This test method is not applicable to the characteriza-tion of materials that dissolve in water to a degree that significantly impacts the void volume in the column or the determination of the specific gravity of the material.
1.7Application of this test method to materials with initial low permeability,or to those that lose permeability over the course of the test,may result in long testing periods.
1.8The values stated in SI units are to be regarded as the standard.The values given in parentheses are in approximate inch-pound equivalents.
1.9This standard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.
2.Referenced Documents
2.1ASTM Standards:
C819Test Method for Specific Surface Area of Carbon or Graphite2
D422Test Method for Particle Size Analysis of Soils3
D698Test Method for Laboratory Compaction Character-istics of Soil Using Standard Effort(12400ft-lbf/ft3)(600 kN-m/m3)3
D854Test Method for Specific Gravity of Soils3
D1125Test Methods for Electrical Conductivity and Re-sistivity of Water4
D1129Terminology Relating to Water4
D1293Test Methods for pH of Water4
D1498Practice for Oxidation-Reduction Potential of Wa-ter4
D1888Test Methods for Particulate and Dissolved Matter in Water5
D2216Test Method for Laboratory Determination of Water (Moisture)Content of Soil and Rock3
D2434Test Method for Permeability of Granular Soils (Constant Head)3
D3370Practices for Sampling Water4
D3694Practice for Preparation of Sample Containers and for Preservation of Organic Constituents6
D4253Test Methods for Maximum Index Density and Unit
1This test method is under the jurisdiction of ASTM Committee D34on Waste Management and is the direct responsibility of Subcommittee D34.01.04on Ancillary Topics.
Current edition approved Oct.10,1995.Published December1995.Originally published as D4874–89.Last previous edition D4874–89.
2Discontinued,see1988Annual Book of ASTM Standards,V ol15.01.
3Annual Book of ASTM Standards,V ol04.08.
4Annual Book of ASTM Standards,V ol11.01.
5Discontinued,see1990Annual Book of ASTM Standards,V ol11.01.
6Annual Book of ASTM Standards,V ol11.02.
1
Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United
States.
Weight of Soils Using a Vibratory Table 3
E 691Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method 7
3.Terminology 3.1Definition:
3.1.1reagent water —as defined in SW-846,Method 1311,5.2.8
3.1.2void volume —the volume between the solid particles in a bed of granular material.Also called the
interstitial volume.
3.2Several terms used in this test method are defined in Terminology D 1129.
4.Significance and Use
4.1This test method is intended to provide an aqueous leaching of a material in a dynamic partitioning manner.
4.2Specific operating conditions for the column can be selected to satisfy the objectives of individual studies.An understanding of the fundamental principles governing column leaching is necessary in the selection of appropriate conditions.References (1-3)9provide useful information on these prin-ciples.
4.3The column apparatus is constructed of materials that permit the generation of a leachate which is suitable for low concentration organic analysis for semivolatile and nonvolatile compounds as well as inorganic species.
5.Apparatus (See Fig.1)
5.1Columns :
5.1.1The column body is constructed of glass pipe,300mm (12in.)in length,with an inside diameter of 100mm (4in.).The cylinder wall must be of sufficient thickness,approxi-mately 6mm (1⁄4in.),to withstand the operating pressure.
7
Annual Book of ASTM Standards ,V ol 14.02.
8
SW-846,3rd ed.,Method 1311,Available from USEPA,Office of Solid Waste and Emergency Response,Washington,DC 20460.
9
The boldface numbers in parentheses refer to the list of references at the end of this
standard.
FIG.1Column
Apparatus
5.1.2End plates are constructed of stainless steel.They are attached by means of eight,6-mm (1⁄4-in.)threaded rods or any other means which ensures a leakproof seal.
5.1.3Gaskets,one at each end of the column,are con-structed of chemically inert materials,and are as thin as possible while still providing a good seal.The gasket diameter should overlap the inside column diameter by 3mm (1⁄8in.)to prevent the gasket from being forced out while under pressure.Techniques o
ther than gaskets for providing a seal between the column and end plates are allowed provided the technique used is specified in the report.
5.1.4Flow distribution disks must be constructed of sin-tered stainless steel,with a nominal pore diameter of 70µm.The disk thickness shall be 6mm (1⁄4in.),with a diameter equal to the inside diameter of the column,approximately 100mm (4in.).The disk shall have eight evenly spaced grooves;each of which is 3mm (1⁄8in.)wide,3mm deep and 50mm (2in.)long.These grooves shall be positioned in a ray originating from the center of the disk.
5.1.5Tubing used in the apparatus shall be of inert materi-als,for example,glass,stainless steel,polytetrafluoroethylene lined.The outer diameter shall be 6mm (1⁄4in.).
5.1.6Substitution of materials of construction of the column or any of its parts is acceptable,as long as it is demonstrated that levels of contamination for analyte(s)of interest are equal to or less than those specified.Any modification of the apparatus as described in this test method must be justified,documented,and delineated in the report.
5.2Pressurized Reservoir Vessel ,which is used to contain the leaching fluid,is constructed with requirements similar to those of the leaching column with the following exceptions:(1)no diffusion disks
are used,and (2)it is equipped with a top port for refilling the fluid.
5.3Balance ,10-kg capacity,with a 1-g sensitivity.
5.4Compressed Gas Source ,prepurified nitrogen or argon with a two-stage delivery regulator (0to 350kPa)(0to 50psig),and a pressure gage capable of measuring the pressure in the head space of the liquid reservoir to within 67kPa (1psig).
6.Reagents and Materials
6.1American Chemical Society (ACS)Reagent grade chemicals or equivalent are preferred.10
6.2Other grades of chemicals may be used,provided that the reagent is of sufficiently high purity to permit its use without compromising the objectives of the testing.
6.3Demonstration of acceptability through reagent blank data at or below the quantitation limits for all analytes of interest is required.
6.4Unless otherwise indicated,references to reagent water mean water as defined in SW-846,Method 1311,5.2.See reagent water under the terminology section of this test method (3.1.1).
N OTE 1—Reagent water is defined in SW-846as water in which an interferant is not observed at or above the method’s detection limit of the analyte(s)of interest.
7.Safety Precaution
7.1General operating pressure should not exceed 275.8kPa (40psig)with materials as defined herein.Other inert materials are available that can be used to manufacture the column which will withstand pressures above 275.8kPa (40psig).8.Sampling
8.1Sampling must be performed so as to obtain a represen-tative sample of the material.
8.2Where no specific sampling methods are available,sampling methods for materials of physical form similar to the material shall be used.
8.3A minimum sample of 5000g,or three column volumes,whichever is larger,shall be sent to the laboratory for each column.
8.4Samples must be kept in closed containers appropriate to the sample type and otherwise protected if necessary prior to testing to prevent sample contamination or constituent change or loss.Where it is desired to test biologically or chemically active samples in their existing state,any sample storage requi
red should be at 4°C (Practice D 3370)and the leaching should be started within 8h of sample collection.Where appropriate,the tester may modify a test portion before leaching to simulate the results of biological or chemical activity in the field.Record the storage conditions,sampling procedures,handling practices,and any abnormal sampling conditions in the report.9.Preparation of Apparatus
9.1The assembled apparatus is shown in Fig.1.9.2Column Preparation :
9.2.1Before use,clean all parts of the test apparatus that will contact the waste material,leaching fluid,or product leachate.
9.2.1.1Clean the sintered disks by boiling them for 15min in reagent water,followed by a backflush with reagent water.Then saturate the disks with concentrated sulfuric acid and soak until all residues are removed.Then vacuum or pressure remove the excess acid with reagent water.Next,pump or draw either acetone or methanol through the disks,followed by either hexane or methylene chloride.Permit disks to air dry.9.2.1.2Clean the column apparatus by washing it with a nonionic surfactant soap and water.Rinse with tap water and follow with a reagent water rinse.Then rinse it with either acetone or methanol,followed by a rinse with either hexane or methylene chloride.Permit the apparatus to air dry.
9.3Assemble the apparatus as depicted in Figs.1and 2.Weigh the dried,clean empty column,including end caps and other fittings necessary to contain the waste,and record the mass.This is the tare of the apparatus.Record the inside diameter and height of that part of the column to be filled with waste (that is,the column cylinder).If,following column saturation,the tester wishes to check the degree of saturation,
10
Reagent Chemicals,American Chemical Society Specifications ,American Chemical Society,Washington,DC.For suggestions on the testing of reagents not listed by the American Chemical Society,see Analar Standards for Laboratory Chemicals ,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeia and National Formulary ,U.S.Pharmaceutical Convention,Inc.(USPC),Rockville,
MD.
it will first be necessary to determine the mass of water that can be contained in the porous flow distribution disks,end plates,and fittings.
10.Procedure
10.1Preconditioning :
10.1.1Prepare a test portion of waste in a manner that simulates the state the waste is in or will be in as it undergoes leaching in the field.Preparation of the test portion may include such factors as curing,and adjustment of moisture content and density.For such adjustments,the following procedures can be used where appropriate.
editorial column10.1.2Moisture Content —Adjust the moisture content to that defined in the disposal scenario by dewatering or adding reagent water to the material.Increase moisture content to that defined in the disposal scenario by addition of reagent water.Note and record the volume of reagent water added.If the concentration of any trace analyte of concern found in the reagent water exceeds the reporting (quantitation)limit for the volume added,note this on the report form.Decrease moisture content by determining scenario temperature (normally less than 60°C)and drying the material at the temperature for a specified time interval.Determine actual moisture content of the waste as it is placed in the column using Test Method D 2216and an appropriate drying temperature.Note and record the drying temperature used.Record the moisture content.10.1.3Density —Density is to be adjusted by vibration (see Test Method D 4253)or compaction (see Test Method D 698)to the anticipated field density.Pack the waste material in the column so that uniform density is achieved.This can be checked by visual ob
servation of the waste in the transparent column.
10.1.4Curing —Aging may be necessary for those materials that undergo physical or chemical changes with time in order to obtain a specimen (test portion)representative of the desired conditions.Curing may be accomplished in the field before testing in the column to produce a physical and chemical state representative of the waste as it undergoes leaching in the field.Note and record field conditions of temperature,humidity,and atmospheric pressure.Record the duration of the curing pro-cess and report with the test data.
10.1.5Particle Size —Ensure that the particle size distribu-tion of the waste as placed in the column is representative of that expected in field placement.Interpretation of results is based in part on a knowledge of the particle size distribution and surface area of the material.Maximum particle diameter must not exceed 1⁄10of the inside diameter of the column.Particle size reduction is not recommended.An evaluation of the particle characteristics of size distribution and surface area may be useful.Test Methods D 422and C 819should be used to evaluate these properties of the waste.10.2Column Filling
:
FIG.2Packing
Configuration
10.2.1Fill the column by compacting or vibrating the waste infive approximately equal layers.Approximate the expected field density.Scarify the top surface of each layer before adding the next increment.Do not scarify the top layer after final compaction.Fill the column to itsfinal height,ensuring that thefinal height of the compacted material is equal to the height of the leaching column.
10.2.2Afterfilling the column,determine the mass,includ-ing the samefittings as in the determination of the tare.Record the total mass.
10.3Leaching:
10.3.1The leaching process is conducted in a continuous up-flow mode.
10.3.2Saturation—After assembling the column as shown in Fig.1,saturate the column with reagent water by the method outlined in Test Method D2434for determining permeability coefficients using a constant head permeameter.In this case, the column assembly replaces the constant head permeameter of that procedure.If it is determined that it is not possible to saturate the waste using Test Method D2434,it may be necessary to increase the vacuum used in the procedure or attempt to saturate the column under pressure,or both,to promote the dissolution of gasses.
10.3.3Water used to saturate the waste should be of the same quality as that to be used to leach the waste in the column.Collect a sample of this water at the time of saturation and analyze for the same properties and constituents as will be measured in the column effluent.An appropriate sample container,similar to that used for sample collection should be chosen and cleaned.Sample container guidance is given in 10.6.1.The test portion will be collected using the procedures for leachate collection.
10.3.4Determination of the Void Volume—V oid volume is estimated from the measurement of specific
gravity of the solids in accordance with Test Method D854,the mass of the wet solids placed into the column,the moisture content of the material in accordance with Test Method D2216,and the volume of the column.Although the drying temperatures used in Test Methods D854and D2216can be selected on the basis of the specific characteristics of the material being dried,the drying temperatures used in the two procedures must be the same for the data to be used for porosity and void volume calculations.
10.3.4.1Measure the mass of the sample material which fills the column apparatus.Note and record the moisture content of the material,as well as the specific gravity and any other specific information relevant to the material.
10.3.4.2Calculate the void volume using the following equation:
V p5V c$M/@~11w!3S3D#%(1) where:
V p=void volume in the column,cm3,
V c=volume of the column,cm3,
M=as-packed mass of the material,including moisture, contained in the column,
w=moisture content of the material contained in the column as a mass ratio from Test Method D2216,g
water/g solids
S=specific gravity of the material as determined in Test Methods D854,unitless,and
D=density of water,g/cm3.
10.3.5Estimate the degree of saturation by calculating the porosity n of the material using the following equation:
n5V p/V c(2) Calculate the mass gain in the saturated material.Add the value of the mass gain to the mass of the water in the packed column.Compare the value to the calculated void volume.The ratio is the degree of saturation.The degree of saturation can be estimated by determining the mass gain due to the water added to the waste during the saturation process,adding this mass gain to the mass of water in the packed column before saturation,and comparing this to the void volume just calcu-lated.The mass gain can be determined by subtracting the mass of the packed,unsaturated column plus the mass of the packed, unsaturated column plus the mass of the water retained in the end plates,flow distribution disks,andfittings,from the mass of the saturated column.
10.4Effluent Flow:
10.4.1Once the column is saturated,begin the testing period.Adjust the pressure or hydraulic head,or both,so that one complete void volume exchange rate is accomplished in24 63h.Maximum operating column pressure,for apparatus specified,should not exceed275kPa(40psig).Read and record operating pressure,and effluent start time.If some test period other than2463h(an alternate void volume period) is warranted,record justification,time interval required,oper-ating conditions,and effluent start time.Collect all column effluents as discrete void volume increments.
10.4.2Operating Requirements—The column must be op-erated continuously.Note and record stop and restart times for all cessations.Determine total stoppage time for each occur-rence per day and total daily stoppage.Cease test if,on any one day,total stoppage exceeds1h.
10.4.3No type of channeling is permitted.When channeling is noted,note the time and cease the test.Determine if samples generated previously are usable.Document rationale for acceptance/rejection of previous sample effluent.Columns shall be protected from extraneous light except during column checks and sample collection intervals.Note and record all exposure periods.
10.4.4Columns are to be run at ambient temperature,under normal test conditions.Sufficient pressure i
s required to maintainflow at the specified rate which will yield a void volume during the specified time interval.Temperature and pressures must be read and recorded periodically.For safety reasons,do not operate this equipment above275kPa(40 psig).
10.5Leachate Collection:
10.5.1The column must be inspected periodically and adjustments made if necessary to maintain the desired operat-ing conditions.
10.5.2Sufficient leachate from void volume periods shall be collected to establish a basis for judgment on completeness
of
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