SOLID WASTE LEACH

TESTING IN REVIEW:

A PERSPECTIVE

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February, 1981

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TD4260571981

vntario

lie HonourableKE.,ith C. Norton. Q.C.,

Min istry M inister

of the Graham VV. S. Scott, Q.C.,Erivironment Deputy Minister

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SOLID WASTE LEACH TESTING IN REVIEW:

A PERSPECTIVE

Frank C. Darcel

Laboratory Services Branch

Ontario Ministry of the Environment

February 1981

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ABSTRACT

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Some aspects of the state of the art on hazard assessment,

leachate movement and waste stabilization are discussed. The rela-

tive merits of batch versus column and lysimeter testing are

evaluated in relation to the wide variety of procedures in use today.

Scientists' concerns over attempts to standardize a test suitable

for all types of waste and conditions and EPA attempts to make

the EP test legally binding are discussed briefly.

Some of the properties of solidified waste are considered in

relation to leach procedures.

Experience with leach testing at the Ontario Ministry of the

Environment Laboratory Services Branch is reviewed. Limitations of

the current procedure of column leaching with distilled water are

discussed in relation to proposed changes in procedure and other

methods of testing.

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1TABLE OF CONTENTS

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INTRODUCTION: 1

Hazard Assessment 2

Leachate Mobilization and Attenuation 5

Waste Stabilization 6

Batch Versus Column Testing 7

Batch Leach Tests 8

Fly Ash Leach Tests 13

"EP" Test 14

Table I 15

Column Tests 17

Lysimeter Tests 21

Solidified Waste 23

Leach Tests at OMOE 25

Proposed Changes in Direction 27

CONCLUSIONS: 30

RECOMMENDATIONS: 31

ACKNOWLEDGEMENTS: 32

REFERENCES: 33

APPENDICES: 40

Figure I - EP Test i

Figure II - Column lysimeter test ii

Figure III - OMOE Leach procedure iii

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SOLID WASTE LEACH TESTING IN REVIEW:

A PERSPECTIVE

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INTRODUCTION

Evidence of leachate migration from landfills is well documented.

Some instances were reviewed by the writer (Darcel, 1975). Migration

was noted in 43 out of 50 sites checked in a United States survey

(USEPA, 1977). Migration of selenium was most common, followed by

arsenic, chromium and lead. Cadmium, iron and mercury were also

above EPA limits in another survey (James, 1977). De Walle and

Chian (1979) more recently reviewed water quality effects. Many of

the landfills in Ontario are inadequate and there is a problem of

illicit dumping often in abandoned gravel pits. This is particularly

serious with hazardous industrial wastes.

It is well known that municipal solid waste will produce a toxic

leachate which should be recycled or treated. Even wood waste can

produce a strong leachate leading to contamination of well water with

iron and manganese (Sweet and Fetron, 1975). This was confirmed

for demolition waste by Ferguson and Male (1980).

Mine operations can produce acidic leachate (Wai et al, 1980),

often with high concentrations of heavy metals.

In the United States, the Resource Conservation and Recovery

Act of 1976 and proposed guidelines of the Environmental Protection

Agency in the Federal Register of December 18, 1978 and August 22,

1979 are having impact on the disposal of solid wastes. Strict

controls are also being implemented in Ontario.

It is becoming increasingly important to determine if a waste

will develop a toxic or hazardous leachate because of the potential

danger to human health. In the United States the Environmental

Protection Agency is proposing that operators of chemical landfills

make a cash deposit large enough to guarantee that each site be

properly closed and monitored for 20 years with $5 million insurance

coverage against possible damage for each site (Maugh, 1979).

Landfills must, therefore, be correctly designed and wastes immobi-

lized or detoxified. Prediction of long term stability (at least

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for 20 years) of a waste As-Is or after chemical stabilization is

becoming, therefore, an important issue. Many patented processes

are currently available for waste stabilization (Ansari and oven,

1980; Pojasek, 1979). An advantage of such processes is that several

compatible wastes can be blended together with desirable chemical

reaction. Laboratory (and field) leach testing will be required for

solidified wastes to be processed by the private sector and by the

Ontario Ministry of the Environment at the proposed landfill in

South Cayuga.

A developing problem in Ontario is the dumping of waste material

at sites licensed only for "clean fill". It then has to be shown

by analysis that the material is not inert. One aspect is that the

material should not generate a leachate significantly different to

that produced by natural processes in the area. This could entail

leach tests on the waste using naturally occurring rock and/or

soil from the area as controls.

The Sediment/Soils (later Sediment/Sewage) unit of the OMOE

Central Laboratories has been conducting extraction tests on

industrial wastes samples submitted by field staff since 1973,

principally by a column water leach test. It was not possible to

conduct a comprehensive survey of the leaching potential of all

the various types of waste in Ontario or to develop optimum testing

conditions due to restrictions on manpower and funding. A colla-

borative study is planned, however, with the Waste Water Technology

Centre of the federal Environmental Protection Service to develop

a data base on toxic wastes, examining various leach procedures.

The present review is intended to help determine the direction

of future studies on solid waste leachability.

HAZARD ASSESSMENT

Attempts are being made to define toxic wastes. The United

States Environmental Protection Agency has prepared lists of potentially

toxic chemicals and proposed criteria for toxic concentrations

of specified metals and organics in an "EP"*test extract (USEPA, 1978).

*Extraction Procedure

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There are criteria in Ontario for mine tailings effluents,

water quality objectives for aquatic life and for human and animal

consumption (OMOE, 1978,1979).

Questions are continually being asked as to whether particular

industrial solid wastes can be "safely" disposed of at specified

landfills. In many instances, such as in illicit dumpings of

material other than "clean fill" attempts should be made to deter-

mine the potential for ground water pollution.

Sewage sludge can have potentially toxic concentrations of

certain metals. Some of this material, meeting the Ontario Sludge

Utilization Guidelines for toxic metals can be used as a soil

amendment. It has been suggested in the United States that the

sludge should be tested by the EP test, similar to an industrial

waste.

Dredged spoil not meeting criteria for open water disposal

should also be tested for hazard assessment (Lee and Jones, 1981).

Anions such as nitrate, cyanide and chloride can be important.

Other potentially toxic materials such as ammonia (Lee and Jones,

1980) and asbestos (McCartney et al, 1981) also have to be considered.

volatile organics can be hazardous (Pojasek and Scott, 1981).

Sight must not be lost of characteristics of a waste in

addition to toxicity which could render it "hazardous". The

United States Environmental Protection Agency (1978) defined the

following groups:

1 Ignitability2 Corrosivity

3 Reactivity4 Toxicity5 Radioactivity6 Infectiousness7 Phytotoxicity8 Teratogenecity and,Mutagenicity

The "Toxicity" was to be determined by an extraction procedure

(described in more detail later) "designed to determine the

pollutants that could migrate from a waste when disposed in an

open dump environment". Only this characteristic of a waste

is discussed in the present report.

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The United States Environmental Protection Agency (1978)

published "Hazardous Waste" lists, itemizing processes generating

hazardous wastes, prohibited pesticides and priority pollutants.

The Ontario Ministry of Environment and Canadian federal agencies

are also working on similar lines.

Daniels (1981) stressed the need for realistic tests for

defining "hazardous". There is no clear cut distinction between

hazard and non-hazard. Persistance and degradation are very

important factors. The possibility of bio-accumulation also has

to be considered.

In the generation of leachate it is often important to

consider the quantity produced in addition to its concentration.

The quantity of leachate can be related back to the original

waste as the percentage or fraction leached.

Attempts have been made to establish criteria for potentially

harmful waste, such as in the USEPA "EP" test. Difficulty occurs

in estimating attenuation and dilution factors for the effect of

ground-water on the ultimate concentration and hence potential

hazard for a given pollutant.

Since the possibility of seepage from a landfill is a real

life situation it is important that tests be devised to predict

leachate potential. It is generally conceded that most reliable

data can be obtained from tests conducted in cells within the

landfill itself. Unfortunately, this route is usually not satis-

factory as a prediction tool, principally because of the lengthy

duration of such a test; it can take years before any leachate

is produced. Usually, no leachate is produced until landfill

material has reached field capacity moisture content. Formation

of leachate can be accelerated by artificially adding water.

An attempt can be made to simulate natural conditions by

leaching the material in relatively large lysimeters or small

columns using material as close as possible to its natural state.

Again, such an approach can require long test periods if it is

intended to determine total release. The process can be accele-

rated by comminuting the particles and shaking them with the

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extractant. Such procedures are, however, even further removed from

natural processes.

Choice of extractant is usually more significant than the

method used for extraction. Extractants used include water (distilled

or natural), acidic solutions with or without buffering, or organic

chelates. Wastes can be evaluated for their stability under

extractant conditions of varying strengths. Testing with water

alone may be satisfactory if it is known that a waste will remain

above the water-table, be isolated from other wastes and from

municipal refuse and will only be subjected to leaching by rain.

Important considerations relating to generation of leachate

are permeability of the waste material and landfill cover (also

surface grade), controlling infiltration as opposed to run-off

(Lowenbach et al, 1977). Permeability (and permanence) of liner

and attenuating properties of the subsoil and underlying rocks

also have to be considered in some situations. In such instances,

a simple shake test approach may not be adequate.

LEACHATE MOBILIZATION AND ATTENUATION

Chemical processes involved in the natural leaching of soils

were reviewed by Wiklander (1974). Similar processes occur to

varying degrees in the leaching of municipal and industrial wastes.

Factors affecting the generation and mobilization of leachate

has been discussed (Hoeks, 1977; Lowenbach, 1978; Fuller et al, 1979).

Redox, pH, temperature, and salt content, in addition to chemical

composition of the pollutant play important roles. For example,

in leaching tests with electroplating sludges, pH was found

to have a major effect on the leaching of Cd and Cr (McCarthy, 1979).

Precipitation reactions, sulphate reduction to sulphide

(precipitating heavy metal sulphides) and organic complexing affect

mobility. The physical blocking of pores in the waste and under-

lying soil or rock by precipitates decomposed organo-iron complexes

or slime (Krofte et al, 1977) in turn affects permeability and hence

leachate migration.

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Mobilization of cadmium is of special interest. In one

leachate, Knox and Jones (1979) found that cadmium was complexed

with <500 M.W simple carboxylic acids and >10,000 M.W. phenolic

hydroxy compounds. The ability to complex cadmium varied with

COD, ranging from 500-10,000 mg/L.

Copper and lead can also form mobile ligands (Harter, 1979).

Precipitation reactions for Cu, Zn and Cd are significant

above pH 6. Exchange on clay minerals is also an important mechanism

with montmorillonite having five times the capacity of kaolinite

(Frost and Griffin, 1977). Vermiculite was an effective adsorber

for Cu and Pb (Harter, 1979).

WASTE STABILIZATION

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There is currently intense activity in the area of waste

stabilization technology and a wide range of encapsulation and

fixation processes are available (Pojasek, 1979; Maugh, 1979;

Landreth, 1979; Lima, 1981). pH is an important factor with

an optimum range of 9 to 11. Interesting developments are the

organic binders; e.g. polybutadiene can be used to bind a waste

into cubes which are then coated with high density polyethylene

(TRW process). Alternatively, waste can be placed in drums which

are then coated with a fibre glass "cocoon". Such processes,

unfortunately, are expensive.

Degree of crystallinity will affect solution rate. In a leach

test with electroplating waste sludge it was found that for waste

aged three months before leaching there were reductions of 86,

33 and 70 per cent, respectively in amounts of Cd, Pb and Cr

leached (McCarthy, 1979).

Crystallinity is also an important consideration in leach tests

with chemically stabilized wastes. Solubility will decrease

after a "curing" period, possibly of several months.

Other important factors are permeability and water absorbion.

Most solidified wastes are highly impermeable, particularly after

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they have been subjected to a consolidation step in landfilling.

Some solidified products can absorb a relatively large quantity of

water; in some instances most or all of the infiltration component

of the rainfall. This water may be transferred back to the atmos-

phere during dry periods; hence there may be no free water available

for producing leachate.

BATCH VERSUS COLUMN TESTING

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There is much discussion as to the relative merits of the two

systems for waste leaching with advantages and disadvantages for

both routes.

Some aspects of various procedures used elsewhere and at the

OMOE Central Laboratories are discussed below. One consideration

that should be kept in mind is that not only chemical but micro-

biological processes may be involved in the leaching of a waste.

This may dictate that a "quickie" test may not be adequate in some

instances, such as when the waste contains metals which can be

biologically methylated; e.g. Hg, As, Pb and Sn.

Solid waste samples as received for testing often contain

significant quantities of liquid which may be contaminated. In

some procedures the sample is tested in situ (with the liquid) such

as in OMOE column tests. In other procedures, such as in the EP

test the free liquid is first removed by pressure filtration. In

tests with metal oxide, hydroxide and carbonate sludges Lancy

et al (1981) found that if the waste was pre-washed laboratory

leach results became more similar to those from the field.

Perket and Webster (1981) reviewed ten of the wide variety

of leach tests that have been used since 1971, including the

Minnesota and ASTM methods.

It was evident that no technique is universally accepted and

there were wide variations in preferred methods of testing. The

general impression was that the leach procedure selected should

be adapted to the nature of the waste disposal site concerned;

hence there can be no universally appropriate laboratory leach

test (West, 1981).

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It is unusual for equivalent results to be obtained by shake

and column tests. However, for some materials and conditions

agreement can be obtained (Jackson et al, 1981). An NBS rotating

mixer, 20:1 liquid:solid ratio and 12 hour contact time was used.

Arsenic was an exception with three times more by the column test.

It was believed that, common to the findings of other workers,

that equilibrium conditions were not attained for As in the shake

test.

Lee and Jones (1981) stressed that it is not possible to

develop one test for all waste and disposal methods. Hazard

assessment should be site specific. Laboratory assessment should

then be compared with the actual behaviour as observed in monito-

ring wells.

BATCH LEACH TESTS

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There is a need for an accelerated environmental test (Pojasek,

1978), which should be realistic (Daniels, 1981). Shake tests

are relatively quick, simple and inexpensive, with good reprodu-

cibility. Unfortunately, it is difficult to obtain reaction

kinetics and interpret the results (Lawenbach, 1978). There is

also a problem due to re-adsorption during an extraction. Separation

of extract must also be complete (e.g. by using a 0.45 uM filter).

The most usual procedure is to shake the material in ground

form with a specified ratio of eluant:solid for a specified time

with single or multiple extractions. Although the test may be

relatively rapid, operator time requirement can be a significant

negative, particularly with multiple extractions.

In some instances, static tests can be used, immersing the

material in a beaker containing the extractant. This may have

relevance, particularly for hard rock-like materials. Lowenbach

(1978) and Perket and Webster (1981) reviewed the multiplicity

of factors affecting leachate generation and their significance.

C6t6 (1981) presented data demonstrating the effects of the more

important factors affecting batch test results.

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Jackson et al (1981) compared results using a rotating mixer

(NBS), a platform mixer (Eberbach) and a roller type mixer.

Liquid to solid ratios were varied from 4:1 to 40:1. More consistent

results for speeds of 10 and 20 rpm wer obtained with the roller

mixer.

Consideration should be given to testing for a "worst case"

situation using a buffered eluant at pH 4-5 at an eluant:solid

ratio of 10-20:1 under anaerobic conditions, and "maximizing"

surface area (Lowenbach, 1978). Test conditions such as the above

could be satisfactory for some waste materials, particularly for

material such as fly ash or foundry sand. However, for compact,

cemented wastes with low permeability, such tests "maximizing"

surface area could indicate completely unrealistic rates of leaching.

The ASTM procedure (ASTM 1977, 1978) involves extraction of

500 g of waste with four times its weight of extractant for forty-

eight hours. Method A for "homogenous" waste uses Reagent Type IV

(distilled water). Method B for "heterogenous" waste uses acetic

acid - sodium acetate buffer at pH 4.5 ± .1. A platform mixer

is used. Jackson et al (1981) felt that there was insufficient

mixing with this procedure.

Results of the ASTM method A test for a Reference Fly Ash

were statistically analyzed in an inter-laboratory program involving

fourteen laboratories in the United States (Webster et al, 1980).

Several areas were noted where tighter control over laboratory

procedures was expected to improve the precision. The ASTM Sub-

committee D.19.12 has modified the method accordingly for inclusion

in the 1981 Book of Standards. The changes include standardization

of the pre-mixing step, and clarification of the sample container

position on the shaker, definition of "strokes" and final separation

procedure. Analytical precision was satisfactory, however. The

above test results illustrate how minor differences in procedure

used in different laboratories can significantly affect inter-

laboratory variability in an extraction test.

Although the extractant medium was water there were wide

differences in pH of the extract, ranging between laboratories

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from 4 to >10. This phenemenon was attributed to differences in

efficiency of mixing noted above. The pH in turn affected the

release of some trace metals. Concentrations of As and Se were

sufficiently high in the extracts to demonstrate the effect of

increased release at higher pH levels. Cr did not correlate with

pH and Cd and Pb concentrations were too low for evaluation.

IU Conversion Systems proposed a forty-eight hour shake test

for adoption by ASTM (Taub, 1976; Lowenbach, 1981). The procedure

is similar to the ASTM Method A test except that concentrations

should be checked from two to forty-eight hours. There were,

however, negative votes because some members of ASTM felt that the

test did not represent natural conditions of leaching.

Welsh et al (1981) compared three acid extractants (Minnesota,

EPA and ASTM Method S). It was concluded that for hazard evaluation

a simple extraction procedure with moderate conditions of extraction

(neither strongly acidic or basic) was adequate. The Minnesota

test was considered to be very aggressive.

Following a comparison of numerous static and shake tests,

Lowenbach (1978) recommended the IU Conversion Systems (IUCS),

the Minnesota and Wisconsin methods for further study. The IUCS

test was considered to be the simplest. Water specific to the

field site is used, if available, to model natural conditions. A

low eluant to waste ratio is used (4:1) which may introduce common

ion effects. In addition, no provision was made for simulating

natural redox conditions.

The Minnesota test uses an acid, highly buffered synthetic

leachate at a 40:1 eluant to waste ratio. Common ion effects

are minimized. The test was considered to be too short

(twenty-four hours) for steady state conditions. In addition

natural redox was not simulated. On the other hand, the Wisconsin

test uses pyrogallol-iron II to adjust redox. The test was

also too short (twenty-four hours) and the 7:1 liquid:solid ratio

could introduce common ion effects. It was suggested that no

single test procedure would fulfil all requirements of the United

States Resource Conservation and Recovery Act.

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The National Council of the Paper Industry for Air and

Stream Improvement (NCASI, 1978) evaluated several extraction

procedures for paper industry wastes, such as board mill and de-

inking sludges. Water, weak and strong acetic acid and synthetic

leachate were investigated, in addition to 1:4 versus 1:7 ratios,

and rotating versus reciprocating shaker motion. other systems

reviewed included the ASTM procedure, the Oak Ridge, Wisconsin and

the Netherlands extraction fluid (pH 5.5). It was generally

concluded that the composition of the eluant was much more signifi-

cant than the extraction procedure or dilution ratio.

McCabe (1979) used two tests to assess the leachability of

an industrial waste-water sludge. The tests consisted of one hour

shaking with distilled water adjusted to pH 4.5 and a water solution

of acetic and butyric acids as extractants.

Ham et al (1979) reviewed the requirements for a Standard

Leach Test (SLT) and the advantages and shortcomings of a modified

IU Conversion Systems test and the Minnesota test. A tumbling

motion was considered to be most effective using water and a

synthetic leachate as extractants. Test conditions were designed

to measure "Concentration" (C) and "Release" (R) by the addition

of fresh waste or fresh leachate, respectively. The relative

"aggressiveness" of different synthetic leachates as extractants

were compared. Eluant:solid ratios of 4:1 or 10:1 were thought

to be superior to the 40:1 of the Minnesota test. As mentioned

earlier Lowenbach (1978) considered 4:1 to be unsatisfactory because

of the possibility of common ion effects.

Multiple extraction shake tests were used by Matchett (1981),with

distilled water and a synthetic acid rain ("Eastern Urban Rain" -

pH 4) currently being promoted by ASTM. Wastes selected for study

were a settling basin sludge from Uniroyal, an incinerator residue

from the SWARU* project and Dofasco "fixed" and "unfixed" waste

from the Ottawa Street slip, Hamilton.

Eluant and solid were mixed using an orbital shaker operated

*SWARU - Solid Waste Reduction Unit

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at low speed to minimize abrasion. Batch kinetic data was generated

using a range of shaking times from one-half to twenty-four hours

(somewhat similar to the IUCS test). Usually most of the soluble

components are leached in one-half hour. Desorption isotherms were

plotted from concentrations obtained by shaking three litres of

eluant in a four litre flask with varying ratios of waste, from

4:1 to 100:1. A ratio of 50:1 appeared to be optimal. For the

tests with solidified waste lumps of about one-half inch were used

(similar to the size used in OMOE column tests). Results were

similar for shake test and column for cumulative leaching of Ca and

Cu from the solidified waste.

The Waste Water Technology Centre, Burlington, Ontario, is

currently developing standardized shake tests with several extractant

systems (C6t4, 1981).

A twenty-five factorial design test (thirty-two combinations)

was run evaluating the effects and interactions of the five main

variables at two levels: agitation method, leaching medium, liquid

to solid ratio, particle size, time of elution and number of elutions.

Agitation by tumbling was found to leach three times that of an

orbital shaker. All variables had a significant effect, particularly

leaching medium.

The preliminary results of the on-going program indicated that

a precise protocol, including a methodology for waste preparation,

should be followed in order to obtain reproducible results.

It was planned to use the test, when conditions have been

defined,for studies on solidification, mobility of toxins in sludge

and in developing information for an industrial waste data base.

A variation of the batch test was used by two private labo-

ratories leaching mine tailings, mineral concentrates and foundry

sands on contract for Mr. R. J. Hawley of the OMOE Waste Management

Branch. The standardized test consisted of extracting 200 g in a

litre of water for forty-eight hours, shaking for a short period

every thirty minutes. The intermittent shaking procedure was used

as it was considered important to minimize abrasion (a consideration

also of Mr. D. Matchett with his test procedure).

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FLY ASH LEACH TESTS

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There is active interest in the leaching of fly ash, no doubt

because it is accumulating at a rapid rate with the increasing

use of coal-fired utility plants with electrostatic precipitators.

Four papers on fly ash were presented at the 1981 ASTM Symposium

on Hazardous Solid Waste Testing (Dodd et al; Miller; Sack et al;

Varnes and Drenski).

In the paper by Dodd et al of Ontario Hydro shake and column

tests were conducted on fly and bottom ash. The results from the

batch tests more closely reflected field experience, at least

in some instances, than the column tests. In the columns there

were problems due to channelling and wall effects (even in six

inch diameter columns) as observed by fluorescent dyes. The ash

was of low permeability (10-5 cm/sec in the field) hence the flow

rate was very slow requiring the tests to be continued for

an unnacceptably long period.

The shake tests used by Ontario Hydro were based on the

procedure proposed by Ham et al (1978, 1979). The tests are

designed to measure "Concentration" and "Release" components of

leaching. Samples are shaken for three cycles of twenty-two

hours with varying ratios of the D.I. water eluant to solid. For

the "Concentration" version of the test a 10:1 ratio is used for

the first cycle. The solid is replaced with fresh solid for the

second and third cycles. For the "Release" version a 10:1 ratio

is used for the first cycle, followed by 7.5:1 and then 5:1 using

fresh eluant for each cycle.

Attempts to find relationships between laboratory leach

tests and disposal site interstitial water and piezometer data

were not totally successful. Possible reasons were channelling

in the columns and too few cycles in the shake tests. Correlaticn

with field data on care samples of ash was also confounded

because of in situ leaching and solute transport in the field

prior to sampling and because of the presence of interstitial

water, contributing to results for concentration in the shake

tests.

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Tests such as the above, therefore, appear to have limited

value in predicting concentrations of trace metals in fly ash land-

fill leachate. Use of mathematical models is a promising approach.

A model predicting concentrations of trace metals in leachate in

conjunction with an attenuation-dispersion model would permit

waste loadings to be adjusted to minimize trace metal pollution

of ground-water (Chapelle, 1980). Data obtained by Theis and

Wirth (1977) by leaching fly ash with water on a horizontal

shaker at controlled pH's of 3, 6, 9 and 12 and analyzing the

extracts for trace metals was used by Chapelle for his models. A

good correlation was obtained between predicted and actual metal

concentrations using proportionality constants (K). The results

supported the assumption of the model that metals will desorb from

fly ash surfaces at a rate proportional to their concentrations on

the surface. For greater confidence, more leach data with time

as a variable was required in addition to calibration of K values

to match landfill chemical condition and leaching rates. K values

can also be expected to be different for each metal because of

differences in mobility in aqueous systems (Goldschmidt, 1954).

"EP" TEST

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The United States Environmental Protection Agency introduced

their EP (Extraction Procedure) test as part of the Hazardous

Waste Guidelines and Regulations in the Federal Register of

December 18, 1978 (USEPA, 1978). The test was designed to define

a toxic waste as that producing an extract under the conditions

of the test (with acetic acid) with concentrations of certain

contaminants exceeding specified levels. These were set at ten

times the EPA National Interim Primary Drinking Water Standards.

Later (USEPA, 1980) these were revised to one hundred times the

Drinking Water standards, partly to more closely reflect ground-

water dilution.

Concentrations in the extract in the revised test are as

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Contaminant Concentration in Extractmg/L

Arsenic 5.0

Barium 100

Cadmium 1.0

Chromium 5.0

Lead 5.0

Mercury 5.0

Selenium 1.0

Silver 5.0

Endrin 0.02

Lindane 0.40

Methoxychlor 10

Toxaphene 0.50

2, 4 D 10

2, 4, 5 - TP Silvex 1.0

The waste had first to be separated from the free liquid,

initially using options of pressure filtration through a 0.45 pM

filter or by centrifugation (the latter option was dropped in

the 1980 revision). The waste was then to be subjected to a

structural integrity procedure using a compaction tester to form

the waste into a cylinder 1.3 inches in diameter by 2.8 inches

high which is then weighed. The cylinder of waste is placed

in a standardized extraction vessel with a stirrer (Figure 1)

and water is added to sixteen times the weight of the waste. After

starting agitation, the pH is adjusted to 5.0 ± 0.2 with 0.5N

acetic acid or until a maximum of 4 mL of acid per gram of waste

is added. Agitation is continued for twenty-four hours. The

solid is then separated from the liquid, diluted to twenty times

the solid waste by weight, and mixed with the liquid initially

separated from the waste. The test is described in detail by

the Millipore Corporation (1980).

There was considerable criticism of the test, e.g. Lee (1979),

McCarthy (1980), American Electroplaters Society (1980), Lee and

Jones (1981) and Malone et al (1981). It is of interest to note

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that Cu and Zn were not included in the parameters although there

are specifications in most water quality guidelines. Arbitrary

factors for attenuation (e.g. one hundred times) should not be used

(Lee and Jones, 1981)

Tests by the American Electroplaters Society demonstrated

that although their hydroxide sludges "failed" the test (at pH 5)

they were stable under natural conditions, as represented by

water leach data. Aging was a very significant factor which was

not considered in the test. A dynamic leach test using a suction

filter was found to be more satisfactory, as described by K. Coulter

at the 1980 Ontario Industrial Waste Conference. Similarly,an

elution procedure was used for metal sludges by Lancy and Penland

(1981).

Malone et al (1981) found that EP test results gave very different

estimates of metals in leachate compared with bulk testing of a

co-disposal situation (industrial plus municipal waste) with over-

estimates of Cd, Ni, Cu and Hg. It was suggested that these

metals should not appear in co-disposal as they are easily preci-

pitated as sulphides.

Warner et al (1981) compared the extractability of various

wastes (ink pigment, baghouse dust, pharmaceuticals, sewage sludge

and organic still bottoms) by a NBS tumbler method (with a 20:1

liquid:solid ratio) and the EP procedure. There were large

differences for metals; in some tests distilled water extracted

more metal than the EP test!

The NBS test extracted much more volatiles than the EP test

(use of screw cap in the NBS test). It was felt that the EP

test was not relevant to secure landfill or solidification processes.

An inter-laboratory study was conducted for the EP test

(Webster et al, 1980) for comparison with data by the ASTM Method A

procedure. A Reference Fly Ash was used. There was poor repro-

ducibility for trace metal results between laboratories with

marginally better precision for the EP test. There was good control

(and measurement) of pH which may have been because the maximum

amount of acid allowed (4 mL 0.5 N acetic acid per gram of solid)

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was not required for the weakly buffered fly ash. The pH effect

for materials requiring the maximum allowable addition of acetic

acid was not evaluated. There was some concern that in such

situations with no pH control higher variability may be obtained

as with the ASTM-Method A.

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As for the ASTM-Method A test, most of the variability was

in the leaching step conducted either in different laboratories or

even in the same laboratory.

Some of the variability could have been due to the use of

stainless steel equipment used by at least some of the participating

laboratories. In the 1980 version of the EP test Teflon coated

equipment was specified as an alternative option for use with acidic

wastes. Both versions of the equipment are now available commercially

(e.g. Millipore, Nuclepore).

Some of the equipment needed for the "EP" test is currently

available at OMOE (excluding the pressure filtration assembly and

automatic titrator). A limited number of waste materials have been

tested using the original version of the test with centrifugation

instead of filtration. Some greasy materials could not be mixed

adequately in the extractor.

The equipment was purchased from Associated Design and Manu-

facturing Company, Alexandria, Virginia (mentioned in the December

19, 1978 Federal Register). The extraction equipment was then

Teflon coated locally to conform with the revision in the Federal

Register of May 19, 1980.

COLUMN TESTS

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Advantages claimed for column tests are low cost, minimal

equipment and a generally more accurate simulation of kinetic

factors affecting environmental systems than is obtained by shake

tests (Lowenbach, 1978). Abrasion is not of concern as it could

be for shake tests. The major disadvantage can be the length of

time to obtain results (days to years).

An important consideration is that the waste is continually

being eluted with fresh extractant whereas in the shake test

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equilibrium conditions can develop between components in solid

and liquid phases which will tend to reduce the quantity extracted

if a one stage extraction procedure is used.

As discussed earlier, biological processes may also be important

in waste leaching leading to organic transformations and biological

methylation of some metals. Organo-metallic compounds may be formed;

some of these can re-enter the external environment away from a

landfill in water soluble or gaseous form. Such processes may take

an appreciable time period to develop and could best be observed

under the conditions of an extended duration column test, particu-

larly if a potentially biologically active (or supportive) eluant

is used.

Environmental Sciences Inc. developed a column leach test to

evaluate "Chem-Fix" treated waste early in the 1970's. The procedure

was used by them to assess water leaching of mercury from Chem-Fix

treated sludge in Thunder Bay, Ontario over the equivalent of

twenty-five years, assuming one third of the rainfall infiltrated

through the waste.

A column test was also used by the writer on mercury containing

wastes (Darcel, 1973). Biologically active BOD water "seeded"

with topsoil was used as an eluant. The test was run for an

equivalent of two years leaching (60 in) over a two month period.

Progressively increasing traces of total mercury (and later methyl

mercury) were found in the leachate. Column and lysimeter tests

have been used in attenuation studies in natural soils, landfill

clay liners and underlying rocks. They have also been used to

test the downward movement of metals from surface applied sewage

sludge, acid precipitation studies and pollutant transport modelling

studies. Posajek (1978) described tests on solidified waste used

by Energy Resources Company Inc. in the United States. Similarly,

large PVC columns (250 cm long x 20 cm diameter), with poly-urethane

insulation, were used by Raveh and Avnimelech (1979) for water

leaching of solid wastes in Israel.

Column leach tests with municipal leachate were described

by Griffin and Shimp (1975). Simulated effluent was used by

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Uradnisheck and Corcoran (1973). Stanforth (1979) also used

synthetic municipal leachate. Problems in the use of natural

leaching due to instability were described by Korte et al (1976)

who suggested the use of carbon dioxide as a preservative.

Column tests with sewage effluent were conducted by de Jong

in 1978. Fuller and Alesii(1979), Chan et al (1978) and Alesii et al

(1980) used municipal solid waste (MSW) leachate. Fuller (1978)

had established that long term or steady state velocities were

established in a column 10 cm long, assuming uniform packing. It

is of interest to note that in the OMOE column tests with 100 g of

waste column length was usually >10 cm. Column diameters ranged

from 3.2 cm to 10 cm in the above studies (3.4 cm was used in recent

OMOE tests). Larger size columns are required for heterogenous

waste (e.g. demolition rubble). Acrylic, PVC, polycarbonate and

aluminum have been used for columns. Glass chromatography tubes

have also been used.

Errors can occur in column tests, particularly for small

columns, due to channelling through non-uniform packing or develop-

ment of cracks. In a study of the transport of ionic salts

Barbarick et al (1980) used a 7.5 cm I.D. column packed uniformly

using a column packing device (Wygal, 1963). Porous ceramic cups,

1.5 cm diameter, were placed at various elevations in the column.

Wall effects can also be a problem at least for some materials,

such as in tests at Ontario Hydro with fly and bottom ash using

10 cm I.D. columns (Dodd et al, 1981).

It is also difficult to simulate redox conditions which could

occur in a disposal site unless a large column is used. The soil

under a disposal site is normally in a reduced state with sulphate

reduction to sulphide (immobilizing some metals) and the formation

of low molecular weight organic acids (acetic, caproic and propionic

acids) in addition to methane (van Engers, 1978). The sulphide

and organic acids would affect metal mobility.

A decision has to be made, therefore, prior to testing if the

leach test is to be conducted under aerobic or anaerobic conditions

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("unsaturated" or "saturated" flow conditions, respectively).

Nitrogen or nitrogen/carbon dioxide blanketting can be used and

the waste continually maintained under liquid, e.g. by the use

of a constant head device.

It is usual to continue column tests with a steady flow of

eluant until steady state conditions for pollutants of interest

are obtained, as observed from a plot of concentration or cumulative

quantity leached versus time, "cut" number or pore volumes. As

an example, Luthy et al (1980) used continuous flow for 90 days,

equivalent to 77.4 pore volumes, in leaching tests with soil/coal

char.

Distilled water is perhaps the most commonly used eluant. It

can be acidified, such as with sulphuric or carbonic acid. Luthy

et al (1980) also used intermediate hard water, model hard water,

acid mine water and an acetate-tartrate-hydrosulphite reagent in

their studies with soil/coal char mixtures.

The use of the last-named reagent was intended to provide a

buffered acidic reducing medium which could more appropriately

simulate anaerobic water-logged conditions in a landfill. The

use of natural and synthetic landfill or sewage effluents as eluants

was discussed earlier.

Concentrations in leachate can be very dependant on whether

or not filtration is used, e.g. through the use of a 0.45 PM

membrane filter. Iron concentrations, particularly, can be affected.

Column tests have been used at OMOE for industrial wastes,

as discussed later. They have generally been of short duration

(three days). In some instances, this may not have been a

sufficiently long time period.

The importance of good landfill design has been stressed. As

this need becomes recognized an increasing need will develop for

attenuation studies on clay liners, underlying soils and rocks

and pollutant barriers. Columns were used by Artiola and Fuller

(1980) to investigate various densitites of packing of limestone

particles compared with Ottawa sand in the attenuation of several

metals (Be, Cd, Fe, Ni and Zn) from municipal solid waste leachate.

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Attenuation was highest for Be and lowest for Cd.

LYSIMETER TESTS

It is appreciated that small column tests can only give an

indication of potential leachate production from a waste. More

representative conditions can be obtained by using large column,

preferably with lysimeters. The writer used such an approach in

a study with solidified waste using distilled water, natural acid

rain-water (from the Haliburton area) and compost leachate (Darcel,

1979).

Modified "Swinnex" suction filters and glass fibre "collectors"

(Stevenson, 1978) placed at various depths in a 15 cm I.D. column

(Figure II) were used to sample pore water rather than rely on

analysis of leachate collected from the bottom of the column. The

test was continued for three months with periods of wetting and

drying. It was found that the leachate collected from the bottom

of the column was similar in composition to the eluant (e.g. when

compost leachate was used) due to by-passing down cracks developing

during the dry periods. Leachate collected from the suction filters

was of relatively good quality.

In some respects the best approach is to use material as

little disturbed as possible. This is sometimes practicable such

as in migration studies in soils. It is also best to use natural

precipitation conditions rather than the use of an artificially

accelerated rate of leaching.

Bourgeois and Lavkulich (1972 a, b) described the application

of silicon carbide lysimeter plates to monitor soil water movement

and chemical quality in forest soils in situ in British Columbia.

This procedure could also have application in pollutant migration

studies. The National Council of the Paper Industry for Air and

Stream Improvement Inc (NCASI, 1979) used ceramic cups to test for

pulp and paper leachate. Results were compared with the U.S.E.P.A.

"EP" test and the ASTM Procedures A and B.

Barbarick et al (1980) used 1.5 cm porous ceramic cups in

their column studies on the movement of ionic salts.

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Jurgens-Gschwind and Jung (1979) reported the results of 50 years

of leaching on permanent cultivated and fertilized plant-lysimeter*

tests in Germany. Similar work (started in 1972 and 1973) is being

conducted using cropped sewage sludge amended soil lysimeter columns

at the Waste Water Technology Centre, Environmental Protection

Service, Burlington, Ontario (Cohen and Bryant, 1978).

Fungaroli and Steiner (1979) used large rectangular lysimeters

(13 ft high x 6 ft x 6 ft) to investigate decomposing solid wastes

and "mini-lysimeters" to determine the effect of shredding in an

"accelerated" test. The mini-lysimeters consisted of 55 gallon drums

(208 litres). Lysimeters were insulated. The tests were run for

1600 days. It was estimated that 75-90% of the water soluble compo-

nents were removed.

Ferguson and Male (1980) demonstrated that comparable results

could be obtained for demolition waste from field monitoring and

on-going laboratory lysimeter studies. The lysimeters were constructed

from two steel drums joined top to bottom (overall height 1.77 m

x diameter of 0.57 m). Each lysimeter was lined with two 6-mil

thick polyurethane liners. Concentrations for lysimeter leachate

for masonry and wood based wastes after six weeks for conductivity,

alkalinity, hardness, iron and manganese were elevated and of the

same order as those for a field site with minimal dilution with

ground-water. Of interest was the high lianin-tannin concentration

in leachate from the wood waste.

On a larger scale, Newton (1977) in Great Britain used a

"simulated" landfill 5 m X 5 m. Tests were run on domestic waste,

oil emulsions, metal hydroxide and cyanide wastes over three years.

It was estimated that the rate of leaching was four times that of

the normal landfill. For Niand Cr <0.2 per cent of the amount

added was leached in 2.5 years.

Field tests are considered to be the most accurate method of

determining the quality and quantity of leachate but they are

expensive, toxic consuming and highly site specific (Lowenbach, 1978).

"Lysimeter" - term also used to describe large column or box forleaching tests

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1SOLIDIFIED WASTE

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Testing of chemically stabilized "fixed" waste is a special

situation. Many of the processes used (particularly the cheaper

ones) include the use of lime and/or calcium carbonate. The material

is made highly impermeable, hence there is minimal surface area

exposed to leaching liquid; in addition, the material will tend to

dissolve in acid media. There may be,therefore, restrictions on

the disposition of such material, particularly if it is not encap-

sulated. It can thus be argued that it is not fair or realistic

to comminute the mass of material before testing or to use acidic

extractants. However, a completely "fixed" waste would be stable

to these conditions.

In the OMOE column tests (OMOE, 1976; Darcel, 1979) air-dried

material was broken into lumps approximately 0.5 inches across,

placed in a column and leached dropwise with water. In some tests

at OMOE the wet sludge was placed in a column As-Is; in some cases

little leachate was obtained due to the low permeability. Similar

tests were conducted by McAndrews and Muthuswami (1978) and Ertel

(1981).

More elaborate and longer duration lysimeter tests with acid

rain water and compost leachate were also conducted at OMOE (Darcel,

1979) as discussed earlier in this report.

Taub (1976) described a "run-off" box devised by I.U.

Conversion Systems to test the stability of their pozzolanic

product "Poz-o-Tec". The test included measurement of the run-off

from a graded surface in addition to the infiltration.

Pojasek (1978) also described the use of large columns for

leaching stabilized waste.

An interesting application of the Soxhlet extractor was

used in the testing of "Soliroc" silicate stabilized waste (Mahieu,

1980). A more rapid and effective procedure for maximizing

contact between eluant and individual particles of "Soliroc" was

devised by Dr. J. Rousseau of Cemstobel S. A., Belgium. The

pulverized material is fluidized (and leached) by a rapidly moving

stream of eluant pumped up through the fluidization zone

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(a 2 cm I.D x 10 cm length glass column) using a peristaltic pump.

The settling zone consists of a large plastic funnel (26 cm I.D at

top) connected by Tygon tubing to the top of the fluidizer. The

solid fraction, providing flow conditions and particle size aggregate

stability and specific gravity are adequately matched, should

settle back into the fluidization zone. The funnel is equipped

with top take-off for discharge and, if required, recycle of

leachate. Some tests using this system were conducted by Mr. B.

Smith and Mr. J. Nesbitt in the laboratory of Walker Brothers Quarries

Ltd., Thorold, Ontario (unpublished). The material was said to

be stable under the relatively severe conditions of this test.

The ratio of eluant to solid is very wide in this test. A

problem could be that concentrations in leachate would then be below

analytical detection limits. Concentrations in leachate could be

increased by multiple recycling of the leachate. Quantities leached

can also be obtained by difference, analyzing original and leached

material. This type of test has application for wastes "fixed" at

the molecular level rather than by cementation or encapsulation.

The eluant water can be acidified and/or buffered, if required, to

provide more aggressive leach conditions.

Thompson (1979) proposed a modification of the Elutriate Test

for sediments (a shake test procedure) for chemically stabilized

waste. This car :)e considered as approaching a "worst case" type

of test.

The ASTM-Method A shake test with distilled water has also been

used for assessing leachability of the cement stabilized waste

"Ligwacon" (Scott, 1980). Low concentrations of metals were

obtained in the extracts, partly due to the mild extractant conditions.

The EP test can also be used as "worst case" test for solidi-

fied waste. Although material tested at OMOE from the Hamilton

landfill was highly sensitive to acidic conditions, there was

so much excess alkalinity that an acidic pH was not attained

under the conditions of the test (with a limit on acetic acid

addition). Leaching of metals was, therefore, not as severe as was

expected.

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At the other extreme, there is a case for use of a static

test, placing a piece of the material in a vessel containing water

for a long period of time and monitoring changes in concentration.

A static test devised by the International Atomic Energy Agency

for measuring the stability of radio-active sludge was used by the

Centre d'Etudes et de Recherches de L'Industrie des Liants Hydrauliques

(CERILH) in France as one of the procedures for evaluating the

leachability of "Soliroc" and other stabilized wastes by water

(CERILH, 1980). In this test a surface of about 13 cm2 is contacted

with 100 mL water at 250C. The water is changed and analyzed after

one month and one year.

A static test on Soliroc was reported by Mahieu (1980) of the

Catholic University of Louvain. Fresh Soliroc dosed with radio-

active isotopes of Cr, Ni, Zn and Co, was poured into a 5 cm I.D

plexiglass cylinder to the 5 cm mark and allowed to cure for one

month. 150 mL of distilled water was then poured above the cemented

mass and allowed to stand. Each day for forty-nine days the water

was changed and analyzed for isotope concentrations on filtered

and unfiltered extracts. Practically no additional metal was

leached after twenty-five days. Some samples were contacted with

the same water for five or six months and the water poured off and

analyzed. Interesting results, relative to the five to six month

concentrations, were obtained for water placed in contact with the

material for only one day after the five to six month test. Concen-

trations were of the same order for Ni and Co as for the five or

six month test and one order higher for Zn. These results tend

to indicate the importance of considering equilibrium conditions.

LEACH TESTS AT OMOE

Some of the earlier work on leach tests, using static tests,

shake tests, columns and lysimeters and the rationale for selecting

a certain method was discussed by the writer in a previous report

(Darcel, 1975). It was stated that the type of test should be

dependent on the nature of the waste, both physically and chemically,

and leaching conditions anticipated in the landfill.

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In the earlier work at the OMOE Laboratory Services Branch a

shake test was used using a 1:50 ratio of solid:extractant using

simulated rain water, neutral and acidified (pH 4.8) 1 N ammonium

acetate, 2.5% acetic acid and 0.005N EDTA. 0.5N H2s04 was used for

some tests. Various types of industrial waste were tested.

The material was shaken on a wrist-action shaker for fifteen

minutes, followed by a second "cut" with fresh extractant. The

shake test was superceded by column tests, usually with 500 g

material, leaching with distilled water. In some tests the water

was saturated with either carbon dioxide (to simulate rain) or

nitrogen for an anaerobic test. Leaching was continued, often for

a prolonged period, collecting a series of leachate cuts which could

be tested for pH, conductivity, metals or phenol, etc. It was

observed for both shake and column tests that acetic acid released

much higher concentrations of Zn and Fe from an automotive plant

filter waste than did distilled water. Similarly, Fe and Cr were

released in high concentrations from a chrome sulphonator sludge.

Ammonium acetate released significantly more Fe and Cr than water

but much less than acetic acid.

Distilled water was most commonly used as the extractant in

subsequent column leach tests (OMOE; Figure III) if it was under-

stood that the material was only to be contacted with rain water.

The test that evolved was 100 g As-Is leached in a 3.4 cm I.D.

acrylic column with three 300 mL "cuts" of distilled water, each

over twenty-four hours (approximating 30 in/annum rainfall and

infiltration). The flow rate was such that the infiltration rate

was usually sufficiently adequate to prevent a build-up of a

hydrostatic head, viz unsaturated flow conditions. A hydrostatic

head would develop above materials of low permeability causing

"unsaturated" flow conditions. Flow would then be assisted by

the development of the hydrostatic head and/or by suction assist.

It was considered useful to determine if the material was of low

permeability. It was also recognized that not only the concen-

tration but the quantity leached in UG (mL x mg/L) of a pollutant

was important. It was also usual to determine the total quantity

of a pollutant present in the original material to obtain some

estimate of the threat to the environment. Lacking was a criteria

for acceptability. Ideally, the leachate quality should meet

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Water Quality objectives, such as those of the OMOE; practically

however, allowance would be made for dilution by ground water.

Since it was attempted to conduct leach tests under controlled

conditions it was felt that the concentrations and/or quantity

leached of a given pollutant from different wastes could be consi-

dered relative to each other and, in some cases, to the total

quantity present in each waste as an assessment of relative

leachability. Since the waste was taken As-Is the first "cut"

could be used to obtain a measure of the immediately mobilized

interstitial liquid in the waste. Differences in concentration

between the second and third cuts were thought to indicate the

solubility of the material. The test was, of course, ineffective

for impermeable materials as there was no leachate. However, such

material was not thought to be an environmental threat except

through run-off and suspension of waste particulates.

More recently, column water leach tests at OMOE have been

involved with evaluating solidified industrial waste at the Upper

Ottawa Street Landfill, Hamilton. The EP was used to evaluate one

batch of solidified waste and has recently been used on a limited

basis for other wastes. The ASTM test has also been used on a

very limited basis.

Some shake tests on mine wastes were conducted recently for

the Ministry by private laboratories, as discussed earlier.

PROPOSED CHANGES IN DIRECTION

Column leach tests will be continued with some modifications

in equipment and procedure.

Consideration is being given to the use of wider diameter

columns (perhaps 10 cm I.D.) at least for coarser types of

waste while maintaining the same minimum depth of 10 cm. It is

also planned to de-water the wastes prior to leaching, analyzing

the liquid phase originally present separately. In the present

procedure 100 g of waste is used As-Is; this will be modified to

specify a standard volume of moderately compacted material after

separation of the free water.

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"Unsaturated flow" (aerobic) conditions will still be used for

some wastes (to be subjected only to rain) using eluants such as

distilled water, distilled water plus carbon dioxide or sulphuric

acid, or natural rain water. For situations where the waste

could be exposed to ground-water or leachate "saturated flow"and

reducing conditions will be employed, in some situations using

natural ground-water or leachate. Where indicated tests will be

run for a longer period than three twenty-four hour "cuts".

Wastes of low permeability will be leached under "saturated

flow" conditions in a modified design of column permitting the

application of increased hydrostatic head to speed up percolation

rate. Where more pressure is required for lower permeability

materials, pump discharge and gas pressurization will be used to

increase flow rate. For some wastes, addition of a filter-aid

such as Celite will be employed.

The possibility of "wall effects" such as those noted by Onartrio

Hydro with fly ash will be addressed. The use of horizontal grooves

cut into the inner surface of the column used in Ontario Hydro's

column design (Dodd et al, 1981) and the use of diffusers will be

investigated.

The use of suction lysimeters with collectors as a means of

minimizing the chance of incomplete and erratic leaching due to by-

passing will be practiced where practicable. Filtration of leachates

will also be more generally practiced using 0.45 uM membrane filters.

It is also planned to evaluate the application of a mechanical

vacuum extractor to provide more uniform and reproducible extraction

conditions. However, this may only have application for certain

types of wastes, e.g. those that have relatively uniform particle

size and adequate permeability.

The testing of stabilized wastes is expected to become an

area of major importance.

Accelerated testing procedures will be evaluated, such as the

use of the fluidized bed concept, with special application for some

types of solidified wastes. The basic apparatus for conducting the

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test (identical to that used by Dr. Rousseau of Cemstobel) was

kindly provided by Mr. Blake Smith of Walker Brothers Quarries Ltd.

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The EP test will also have some application in testing stabilized

wastes. Modific:ationa of the procedure will also be evaluated,

such as the effect of weaker and stronger extractants, adjustment

to different pH values, variations in particle size, etc.

Consideration will also be given to the static test approach

and the practicability of using radio-active tracers.

Run-off boxes, similar to those used by I.U. Conversion Systems

have been constructed and will be tested with suitable wastes.

New developments in shake tests will be pursued, particularly

tests determining "Concentration" and "Release" parameters. Orbital

and end-over-end mixing procedures will be evaluated. An exchange

of samples and data will be made with the Waste Water Technology

Centre, Burlington. Leach data will be compared between laboratories

and in the field and with measurements on interstitial water with a

view to characterizing wastes and standardizing on the most suitable

methodology.

The above proposals will necessitate funding and technical

time for development studies and effective implementation. It

can be expected that the man-power requirement per test will

increase very significantly compared with that for the present

routine simple column test; however, the generation of more

useable data will outweigh the additional cost.

The present allocation of time for leach tests in the sediment/

Sewage Laboratory is only 0.5-1 technician-days per week due to

pressure of other routine work. This does not permit time for

experimentation on improvements in procedure, such as those pro-

posals recommended in this paper.

A summary of OMOE data on leach tests will be presented

later as a separate report.

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CONCLUSIONS

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There is obviously a wide diversity of opinion as to the best

way to test the leachability of wastes. In the opinion of the writer

the present column water-leach procedure used at OMOE still has

merit as a guide to the stability of a waste under certain conditions

of disposal viz the waste is segregated from other wastes, is not

subjected to surface flooding or to ground-water, and is exposed only

to rain-water. In some cases where it is practicable, it is also

to be understood that rain-water infiltration will be minimized

by an impervious cover.

The present test, therefore, has significant limitations. The

test procedure can be improved to make it more representative of

field conditions.

The improbability of being able to devise a test which will

suit all conditions has to be recognized. The test program for

a particular waste will still have to be based on its special

characteristics and those of the disposal site. There is, however,

an urgent need for procedure(s) which can rapidly determine the

toxicity and leachability (indicating short and long term stability)

of industrial solid wastes alone or after "fixation".

-30-

1

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F1

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RECOMMENDATIONS

The collaborative study with the Waste Water Technology Centre

on leach testing and preparation of a toxic waste data base should

proceed as planned.

Pending development of improved methodology, the use of existing

OMOE procedures should be continued with minor revisions, as

discussed in this report.

Rapid laboratory shake and column procedures should be designed

to test for "worst case" as well as for environmental conditions

considered relevant for each waste-landfill situation.

The scope of the tests should be expanded to include the leaching

of low level radio-active wastes.

Results and conclusions of rapid small scale laboratory tests

should be confirmed by rigorous long term testing using large

columns in the laboratory and in situ testing of segregated cells

in a landfill.

Mathematical modelling should be initiated in conjunction with

the Hydrology and Monitoring Section of the Water Resources Branch

and Ontario Hydro to obtain better predictions of field conditions

from laboratory tests. This approach could be worth-while for

relatively homogenous wastes produced in large quantity, e.g. fly

and bottom ash, foundry sand, mine tailings and, in the future

flue gas desulphurization (F.G.D.) waste.

Criteria of acceptability should be established by the Waste

Management Branch once data has been obtained from intensive

laboratory and field testing.

Funding and man-power should be provided to support the proposed

test program. The Laboratory will then be able to provide more

effective assistance in programs to reduce and eventually eliminate

hazards from the landfilling of industrial wastes.

-31-

ACKNOWLEDGEMENTS

1

P,

1

Appreciation is extended to Mr. Blake Smith of Walker Brothers,

Thorold and to Mr. Colin West of the Regional Municipality of Hamilton-

Wentworth for their comments on the first ASTM Symposium on Hazardous

Solid Waste Testing (held in Florida) which the writer was unable

to attend. Published proceedings are not expected for several

months. These comments and those of Dr. Arnold Golomb of Ontario

Hydro and Mr. Den Coulter of the American Electroplaters Society

permitted an up-date of current thinking on waste leaching. Useful

discussions were held with Dr. George Hughes of the OMOE Hydrology

and Monitoring Section, Mr. Dave Matchett of the West-Central Region,

and Mr. John Hawley of the Waste Management Branch of the Ontario

Ministry of the Environment.

Mr. B. Neary, Supervisor, Inorganic Trace Contaminants Section

of the Laboratory Services Branch kindly reviewed the draft of this

report.

-32-

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REFERENCES

ALESII, B.A., FULLER, W.H. and BOYLE, M.V., 1980. Effect ofleachate flow rate on metal migration through soil.J. Environ. Qual. 9 (1): 119-126.

American Electroplaters Society, 1980. Electroplating waste-water sludge characterization. Final Report AES-EPA Coopera-tive Agreement No. R 880026-01.

American Society for Testing Materials, 1977. Proposedstandard test methods for leaching of waste materials.D 19.12.03.

Ibid 1978. Proposal (for information only) test methods forleaching of waste materials.

ANSARI, A. and OVEN, J., 1980. Comparing ash/FGD waste dis-posal options. Pollut. Eng. May 1980: 66-70.

ARTIOLA, J. and FULLER, W.H., 1980. Limestone liner forlandfill leachates containing beryllium, cadmium, iron,nickel and zinc. Soil Sci. 129 (3): 167-179.

BARBARICK, K.A., KLUTE, A. and SABEY, B.R., 1980. Applicationof sewage effluent to columns of a mountain meadow soil: I

Errors in calculating the transport of ionic salts. SoilSci. Soc. Am.J. 44:921-924.

BOURGEOIS, W.W. and LAVKULICH, L.M., 1972a. Application ofacrylic plastic tension lysimeters to sloping land. Can. J.Soil Sci. 52:288-290.

Ibid 1972b. A study of forest soils and leachates on slopingtopography using a tension lysimeter. Can. J. Soil Sci. 52:375-391.

Centre d'Etudes et de Recherches de l'industrie des liantshydraulics, 1980. Study program on the stabilization ofindustrial sludge and definition of tests in Proctor andRedfern Ltd., Limited. Term Liquid Industrial Waste Solidi-fication Facilities. Environmental Assessment, Appendices toVolume II, May 1980.

CHAN, K.Y., DAVEY, B.G. and GEERING, H.R., 1978. Interactionof treated sanitary landfill leachate with soil. J. Environ.Qual. 7 (3):306-310.

CHAPELLE, F.H., 1980. A proposed model for predicting tracemetal composition of fly-ash leachates. Environ. Geol.3:117-122.

COHEN, D.B. and BRYANT, D.N., 1978. Chemical sewage sludgedisposal on land (lysimeter studies) Volume II. Project No.72-3-6. Research program for the abatement of municipalpollution under the provisions of the Canada-Ontario agree-ment on Great Lakes water quality.

-33-

COTE, P., 1981. Important factors of a batch leaching test.16th Symposium on Water Research in Canada. University ofToronto, February 19.

1

1

1

1

1

1

1

DARCEL, F.C., 1973. Leaching study on Canadian IndustriesLtd. mercury containing sludge, Hamilton. Ontario Ministryof Environment (unpublished).

DARCEL, F.C., 1975. Analysis of leachate from industrialsolid waste disposal sites. 22nd Ontario Industrial WastesConf.

DARCEL, F.C., 1979. Lysimeter and column testing ofsolidified industrial waste from the Upper Ottawa Streetlandfill, Hamilton.Ontario Ministry of the Environment.

DANIELS, S.L., 1981. The development of realistic testsfor effects and exposures of solid wastes. 1st ASTMSymposium on Hazardous Solid Wastes Testing.

JONG, de, E., 1978. The movement of sewage effluent throughsoil columns. The major ions (Na, Ca, Mg, Cl and SO 4).

J. Environ. Qual. 7 (1):133-136.

WALLS, de, F.B. and CHIAN, E.S.K., 1979. Solid wastes andwater quality. Jour. Water Poll. Control Fed. 51:1402.

DODD, D.J.R., GOLOMB, A., CHAN, H.T. and CHARTIER, D., 1981.A comparative field and laboratory study of fly ash leachingcharacteristics. 1st ASTM Symposium on Hazardous SolidWastes Testing.

Environmental Sciences Inc. Leaching tests for solidsdeveloped from treatment of industrial wastes. Data sheet 105.

ERTEL, G.L., 1981. Solidification of an industrial sludge,:solutions for Industrial Wastes Disposal Seminar, PollutionControl Association of Ontario. Ontario Ministry of Environment.

FERGUSON, D.W. and MALE, J.W., 1980. The water pollutionpotential from demolition waste disposal. J. Envir. Sci.Health A 15 (6):545-559.

FROST, R.R. and GRIFFIN, R.A., 1977. Effect of pH onadsorption of copper, zinc and cadmium from landfillleachate by clay minerals. J. Environ. Sci. HealthA 12 (4 & 5):139-156.

FULLER, W.H., 1978. Investigation of landfill leachatepollutant attenuation by soils.EPA 600/2 - 18-158.USEPA, MERL, Cincinnatti, Ohio, p. 239.

FULLER, W.H., ALESII, B.A. and CARTER, G.E., 1979. Behaviourof municipal solid waste leachate I Composition variations.J. Environ. Sci. Health A 14(6):461-485.

FULLER, W.H. and ALESII, B.A., 1979. Behaviour of municipalsolid waste leachates II In soil. J. Environ. Sci. HealthA 14(7): 559-592.

-34-

FUNGAROLI, A.A. and STEINER, R.L., 1979. Investigation of

sanitary landfill behaviour. Drexel University, Philadelphia,

Pa. EPA-600/2-79-053 a.

I

1

1

1

1

1

1

P

1

GOLDSCHMIDT, V.M., 1954. Geochemistry: Fairlawn, N.J.

Oxford University Press 730 pp.

GRIFFIN, R.A. and SHIMP, N.F., 1975. Interaction of clay

minerals and pollutants in municipal leachate. Proc. 2nd

Nat. Conf. on Complete Water Use. Am. Inst. Chem. Eng.

Chicago. May 4-8.

HAM, R.K., ANDERSON, M.A., STANFORTH, R. and STEGMANN, R.,

1978. The development of a leaching test for industrial

wastes. Proc. Conf. of Applied Research and Practice on

Municipal and Industrial Wastes, Madison, Wisconsin.

Sept. 10-13, 1978.

HAM, R.K., ANDERSON, M.A., STANFORTH, R. and STEGMANN, R.,

1979. Comparison of three waste leaching tests. Univ. of

Wisconsin. Executive Summary: EPA 600/8 - 79-001.

Report: EPA 600/2 - 79-071.

HARTER, R.D., 1979. Adsorption of copper and lead by Ap and

B2 horizons of several northeastern United States soils.Soil Sci. Soc. Am. J. 43:679-683.

HOEKS, J., 1977. Mobility of pollutants in soil and ground-

water near waste disposal sites. Effects of urbanizationand industrialization on the hydrological regime and on

water quality. Symposium, Amsterdam.

JACKSON, K.F., BENEDIK J. and JACKSON, L., 1981. Comparison

of solid wastes batch extraction tests with a column

leaching method. 1st ASTM Symposium on Hazardous Solid

Wastes Testing.

JURGENS-GSCHWIND, S., and JUNG, J., 1979. Results of

lysimeter trials at the Limburgerhof facility, 1927-1977:The most important findings from 50 years of experiments.Soil Sci. 127 (3):146-160.

JAMES, S.C., 1977. Metals in municipal landfill leachateand their health effects. AJPH 67 (5):429-432.

KNOX, K. and JONES, P.H., 1979. Complexation characteristicsof sanitary landfill leachates. Water Res. 13:839-846.

KORTE, N.E., NIEBLA, E.E. and FULLER, W.H., 1976. The use

of carbon dioxide in sampling and preserving naturalleachates. Jour. WPCF 48 (5):959-961.

KROPF, F.W., LAAK, R. and HEALEY, K.A., 1977. Equilibrium

operation of subsurface absorption systems. Jour. WPCF

Sept. 1977:2007-2016.

-35-

1

1

P

1

1

P,

fl

LANCY, L.E. and PENLAND, J.L., 1981. Modified leach testincorporating an elutriation step for the evaluation ofmetal sludges. 1st ASTM Symposium on Hazardous SolidWastes Testing.

LANDRETH, R.E., 1979. Survey of solidification/stabilizationtechnology for hazardous industrial wastes. U.S. ArmyEngineers Waterways Experiment Station, Vicksburg, Miss.EPA 600/2 - 79-056.

LEE, G.F., 1979. Comments on December 19, 1978 FederalRegister "Guidelines for Hazardous Waste Management"Environmental Engineering, Colorado State UniversityOccasional Paper No. 39.

LEE, G.F. and JONES, R.A., 1980. Comments on US EPA proposalto add ammonia to toxic pollutant list. Occasional PaperNo. 51. Dept. Civil Engineering Colo. State Univ.

LEE, G.F. and JONES, R.A., 1981. A hazard assessment approachfor interpreting the results of hazardous waste leaching testsusing dredged sediment as an example. 1st ASTM Symposium onHazardous Solid Wastes Testing.

LIMA, J.V., 1981. Evaluating landfilling of stabilizedindustrial waste. 1st ASTM Symposium on Hazardous SolidIndustrial Wastes 't'esting.

L6WENBACH, W., 1978. Compilation and evaluation of leachingtest methods. Municipal Environmental Research Laboratory.Cincinnati, Ohio. EPA - 600/2 - 78-095. Mitre Corp.

LOWENBACH, W., ELLERBUSCH, F. and KING, J.A., 1977. Leachingtesting techniques surveyed. Water & Sewage Works. Dec: 36.

LUTHY, R.G., VASSILIOU, P. and CARTER, M.J., 1980. Leachcharacteristics of coal-gasification char. J. Env. Eng.Proc. Am. Soc. Civil Eng. 106:No. EE1:81-103.

MACKAY, D. 1979. Finding fugacity feasible. Envir. Sci.& Tech. 13 (10):1218-1223.

MAHIEU, B., 1980. Insolubilisation et enrobage de dechetsindustriels par le proceddf >oliroc. In Proctor and RedfernLimited. Term. Liquid Industrial Waste SolidificationFacilities. Environmental Assessment, Appendices to Volume II.

MALONE, P.G., LARSON, R.J., MYERS, T.E. and SHAFER, R.A., 1981.Evaluation of the Extraction Procedure testing of hazardousindustrial wastes in a co-disposal situation. lst ASTMSymposium on Hazardous Solid Waste Testing.

MARSHALL, D.W. and BLOSSER, R.O., 1981. Nature and environmentalbehaviour of manufacturing - derived solid wastes of pulp andpaper industry origin. 1st ASTM Symposium on HazardousSolid Wastes Testing.

-36-

1

1

1

1

1

MATCHELT, D., 1981. Solubility tests for industrial waste

materials. Master's thesis. Department of Civil Engineering,McMaster University, Hamilton.

MAUGH II, T.H., 1979. Burial is last resort for hazardouswastes. Science 204:1295-1298.

McANDREW, R.T. and MUTHUSWAMI, S.V., 1978. Technicalassessment of a solidification process for treatingindustrial liquid wastes. Univ. Toronto.

McCABE, D.J., 1979. Environmental assessment of the disposalof industrial wastewater residuals in a sanitary landfill.J. Environ. Sci. Health A14 (6):443-460.

McCARTHY, J.A., 1979. Characterization of the leachabilityof electroplating wastewater treatment sludges. Plating

and Surface Finishing. December:32-34.

McCARTHY, J.A., 1980. Personal communication, Jan. 29, 1980.

CENTEC. 11800 Sunrise Valley, Dr. Reston, Va. 22091.

McCARTNEY, M.C., RINALDO-LEE, M.B., NAGLE, D.L. and RYAN, T.G.,

1981. Laboratory and field evaluation of landfills for

asbestos containing wastes. lst ASTM Symposium for HazardousSolid Wastes Testing.

MILLER, M., 1981. Study of two fly ash fill sites throughsurface water monitoring and laboratory leachate analysis.1st ASTM Symposium on Hazardous Solid Wastes Testing.

Millipore Corporation, 1979. Hazardous waste filtrationprocedure. Technical Service Brief.

NC AS1, 1978. Response of selected paper industry sludges

to alternate solid waste toxic extraction procedures.National Council of the Paper Industry for Air and StreamImprovement Inc. Tech. Bull. 311.

NC ASl, 1979. Nature and environmental behaviour ofmanufacturing - derived solid wastes of pulp and paperorigin. Stream Improvement Tech. Bull. No. 319. NationalCouncil of the Paper Industry for Air and StreamImprovement Inc.

NEWTON, J.R., 1977. Pilot scale studies of the leachingof industrial waste in simulated landfills. WaterPollut. Control 1977:468-478.

Ontario Ministry of the Environment, 1976. An assessmentof a process for the solidification and stabilization ofliquid industrial wastes. Ontario Ministry of EnvironmentPollution Control Branch.

Ibid 1978. Water Management.

Ibid 1979. Guidelines for Environmental Control in theMining Industry (Revised).

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C

PERKET, C.L. and WEBSTER, W.C. Literature review oflaboratory leaching and extraction procedures. 1st

ASTM Symposium on Hazardous Solid Waste Testing.

PAJASEK, R.B., 1978. Stabilization, solidification ofhazardous wastes. Environ. Sci. Tech. 12 (4):382-386.

POJASEK, R.B., 1979 (Editor). Toxic and Hazardous WastesDisposal. Volumes I and II. Ann Arbor Science Publishers Inc.

POJASEK, R.B. and SCOTT, M., 1981. Surrogate screening forvolatile organics in contaminated media. 1st ASTM Symposiumon Hazardous Solid Wastes Testing.

RAVF.H, A. and AVNIMELECH, Y., 1979.Leaching of pollutantsfrom sanitary landfill models. Jour. WPCF 51 (11):2705-2716.

SACK, W.A., BOOMER, B.A., TARANTINO, J.T., KEETER, G.B.,

SEALS, R.K. and MILLER, M. Evaluation of fly ash leachabilityusing several batch leaching procedures. 1st ASTM Symposiumon Hazardous Solid Wastes Testing.

SCOTT, M.P., 1980. Solidification facilities for liquidindustrial waste. Environmental Assessment Report.Volume II. M.M. Dillon Ltd.

STANFORTH, R., HAM, R., ANDERSON, M. and STEGMANN, R., 1979.Development of a synthetic municipal landfill leachate.Jour. WPCF 51(7):1965-1975.

STEVENSON, C.D., 1978. Simple apparatus for monitoringland disposal systems by sampling percolating soil waters.Environ. Sci. Tech. 12 (3):329-331.

SWEET, H.R. and FETROW, R.H., 1975. Ground-water pollutionby wood waste disposal. Groundwater 13:227.

TAMB, S.I., 1976. Treatment of concentrated waste water toproduce landfill material. Int. Poll. Eng. Expos. andCongress. Anaheim, California, November 10.

THEIS, T.L. and WIRTH, J.L., 1977. The sorbtive behaviourof trace metals on fly ash in aqueous systems. Environ.Sci. Technol. 11 (9):1096-1100.

THOMPSON, U.W., 1979. Elutriate test evaluation of chemicallystabilized waste materials. Env. Protection Agency EPA-600/2-79-154.

United States Environmental Protection Agency, 1977. Theprevalence of subsurface migration of hazardous chemicalsubstances at selected industrial waste land disposal sites.Final Report SW-634.

Ibid 1978. Hazardous wastes. Proposed guidelines andregulations on identification and listing. Federal Register,Monday, December 18, 1978. Part IV.

Ibid 1980. Hazardous wastes management system: General.Federal Register, May 19, 1980.

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URADNISHECK, J. and CORCORAN, W.H., 1979. Anomalies in cation

concentrations during percolation of simulated effluent through

sand. JWPCF 51 (11):2691-2704.

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VAN ENGERS, L., 1978. Mineralization of organic matter in the

subsoil of a waste disposal site: A laboratory experiment.

Soil Sci. 126 (1):22-28.

VARNES, A.W. and DRENSK, T.L., 1981. Comparison of AA and ICP

for metals in fly ash leachates. 1st ASTM Symposium on Hazadous

Solid Wastes Testing.

VILLAUME, J.F., 1981. Use of a batchwise extraction for coal ash

disposal evaluation. 1st ASTM Symposium on Hazardous Solid Wastes

Testing.

WAI, C.M., REECE, D.E., TREXLER, B.D., RALSTON, D.R. and WILLIAMS, R.E.,

1980. Production of acid water in a lead-zinc mine, Coeur d'Alene,

Idaho. Environ. Geol. 3:159-162.

WARNER, J.S., HIDY, B.J., JUNGCLAUS, G.A., MCKOWN, M.M., MILLER, M.P.

and RIGGIN, R.M., 1981. Development of a method for determining the

leachability of priority pollutant organic compounds from solid

wastes. 1st ASTM Symposium on Hazardous Solid Wastes Testing.

WEBSTER, W.C., JACKSON, K.F. and PAULE, R.C., 1980. Analysis of

selected trace metals in leachate from reference fly ash. Phase II.

Supplemental leaching program U.S. Dept. Energy - ASTM Committee

D 34.

WELSH, S.K., GAGRON, J.E. and ELNABARAWY, M.T., 1981. Comparison of

three acid extraction in leaching test protocols. 1st ASTM Symposium

on Solid Waste Testing.

WEST, C., 1981. Personal communication, February 10, 1981.

WIKLANDER, L., 1974. Leaching of plant nutrients in soils. Acta

Agricultura Scandinavica 24:349-356.

WYGAL, R.G., 1963. Construction of models that simulate oil

reservoirs. Soc. Petrol. Eng. J. 3:281-286.

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1

APPENDICES

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1FIGURE I - EP TEST

SAMPLE

1

i

i

-- 3.1 D -"

POLYURETHANE .

SAMPLEHOLDERtuKrA

COMPACTION TESTERpoments*Polyurethane foam shell conform

t0requir

for Grade 21, performance Grade

established In ASTM Standard D3453.

Dimension in inches

NON CLOGGING SUPPORT BUSHING

1 Inch BLADE AT 30' TO IIORIZ014TAL

EXTRACTORUSEPA, 1978

-i-

1

COLUMN LYSIMETER TEST

1LY S I METER

1

RESERVOIR

FIGURE II

ACID RAIN WATER

1

SUCTIONTUBESTYGON

SIDEPORTS

(not used)

1

DRIP TUBETECHNICON

COMPOST55 cmCOMPOST LEACHATE

SOLIDIFIEDWASTE

SUCTIONFILTER

SWINNEX"MID" LEACHATE

75 cm

1

BOTTOMLEACHATE

"DEEP" LEACHATE

GRAVEL LAYER

ELL-i BASE STAND

15 cm

Darcel, 1979

1FIGURE III

OMOE LEACH PROCEDURE

1

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P

WasteColumn

Drain forunsaturatedflow

Reservoir

Drip tube

i

U-tube Assembly(for saturated flow only)

Leachate CollectionVessel

n

1

1