United States       Solid Waste and
              Environmental Protection  Emergency Response   EPA530-R-94-020
              Agency         (5305)             May 1994
vvEPA
Sampling and Analysis
Of Municipal Refuse
Incinerator Ash
              DRAFT
           Recycled/Recyclable
       "). ~O Printed on paper that contains at
                    7").
                    \_]f_/ least 50% post-consumer recycled fiber

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                           INTRODUCTION
                                                DRAFT
     The purpose of this document is  to  assist generators of ash
from municipal incinerators in designing a  plan  to determine
whether any constituent in the ash exceeds  the levels  specified
in EPA's Toxicity Characteristic (TC).

     Determining whether a waste passes  or  fails the TC requires
reliable information on the chemical  properties  of the waste.
Several factors contribute to this reliability.   Accuracy can be
achieved by collecting and testing enough unbiased samples to
determine the average properties of the  waste and its
variability.  Bias can be prevented by incorporating randomness
into the sampling collection process, and precision can be
obtained by selecting an appropriate  sampling interval and number
of samples.

     This document provides general guidelines on approaches for
achieving these goals.   Users are reminded, however, that this
guidance must be adapted to the particular  facility under
consideration to assure accuracy in determining  whether wastes
pass or fail the TC.   This document is based on  limited
information on municipal waste resource  recovery incinerators.
The sampling and testing described represents the minimum that
the Agency considers  as being appropriate.  As the Agency obtains
more information on these facilities, this  document may be
revised.   In the meantime,  facility owners  should use this
document as a general guidance in developing a facility-specific
plan.

     This document contains the following sections:

     1.   Sampling:   Describes how to design a sampling plan,
          including type and frequency of sampling, as well as
          location.

     2.   Analysis:   Describes the  specific procedures from "Test
          Methods for Evaluating Solid Waste" (SW-846)  for the
          species listed in 40 CFR  261.24.

     3.   Strategy for  Evaluating Samples:  Describes criteria
          for evaluating data to determine which  wastes pass or
          fail the TC and the frequency  of recharacterization.

     4.   Quality Assurance and Quality  Control:   References
          procedures  to follow to insure  the quality of the
          sampling and  analysis data.


                                                  ENVIRONMENTAL
                                                    PROTECTION
                                                      AGENCY
                                                   DALLAS, TEXAS

                                                   LIBRARY

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                                                Di
                             SAMPLING
     The objective of sampling and analysis is to assess the
properties of the waste being generated.  Each residual waste
stream that is stored, transported, or disposed of as a separate
unit is considered to be a discrete waste and must be evaluated
accordingly.  You must determine whether the ash from your
facility passes or fails the TC.

     The sampling plan described in this document represents the
Agency' s current thoughts on what constitutes the minimum amount
of sampling needed to determine the average property of the ash
from the combustion of municipal refuse.  As noted later,
facility operators are responsible for evaluating the waste to
ascertain its variability over time.  Currently,  the Agency
believes that, at a minimum, seasonal rechecking of residual
properties is necessary to insure that the waste has not
substantially changed.

     The sampling strategy for evaluating the ash is based on the
assumptions that 1) the waste feed prior to incineration is not
segregated by type of generator (e.g., household, commercial,
industrial)  and 2)  the ash generated is not separated by size
during storage or disposal.  The strategy is designed to
determine the average concentration of TC analytes. If the above
assumptions are not valid, then a facility-specific sampling and
analysis program designed by knowledgeable personnel should be
employed.

     For characterizing ash from facilities for which all of the
above assumptions apply, the sampling procedure is as follows:

     1.  Determine the most convenient location for sampling.  In
     situations where the sampling can be conducted either from
     transport vehicles or from the waste conveyance device, the
     Agency recommends sampling from the transport vehicle  (e.g.,
     dump truck, barge) .

     2.  Construct a sampling device  (trough,  bucket, shovel,
     thief,  etc.) to be used to gather a grab sample of the
     entire depth of the hopper, pile, or truck load, or the
     entire width of the belt conveyor, drag chain flight, or
     vibrating conveyor.  A draft practice for sampling
     unconsolidated waste materials from trucks is currently
     under development by ASTM Committee D-34.  Pending
     completion of the standard, this draft practice may be used
     for guidance on appropriate procedures for sampling ash from
     trucks .

     3.  If a conveyor is to be the sample location, collect the
     entire width of the conveyor at a fixed point each hour for
     eight (8) hours.  If trucks are to be sampled, randomly
     select 8 trucks to sample during the eight  (8) hour period.
     In certain situations, where less than 8 truckloads are

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generated, a different schedule may be necessary  (e.g.,  less
than 1 truck per hour).  Composite all samples for the
period into an eight  (8) hour composite.  Containerize,
label, and set aside  for further processing.

4.  Collect a second  eight  (8) hour composite during the
course of the work day.  The second composite should be
collected during a different shift from the first composite.

5.  For an initial waste characterization, samples should be
collected each day for a minimum of one week's operation.

6.  Each composite is to be passed over a 2 inch screen.
Material passing the  2 inch screen is to be set aside.
Material >2 inches is to be subjected to repeated blows with
a five (5) pound sledge hammer dropped from one foot above
the >2 inch size pieces. If a piece does not break after
 eing subjected to three (3) blows of the hammer, it is to
be weighed and discarded.  Material that breaks is then
reduced in size to pass the 2 inch screen and recombined
with the original <2  inch sample.  As an alternative,
facilities may reduce all material in a composite to pass a
3/8 inch  (9.5 mm) screen and not discard any components of
the composite.

7.  Each composite should be crushed to pass a 3/8 inch  (9.5
mm)  screen,  and riffled or coned and quartered to obtain a
1000 gram aliquot.  Properly label the sample and store it
in a clean,  dry,  cool secure area.  For further details, see
ASTM standard D346.

8.  Analyze the composite samples for the properties of
interest.

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                                                     RAi
i.r
                             ANALYSIS
     In order to determine whether the ash exhibits the TC,  100
gram or larger size aliquots of each eight hour composite shall
be tested using Method 1311 and the extract analyzed for the
species listed in 40 CFR 261.24.  All testing shall be performed
following the specific procedures described in "Test Methods for
Evaluating Solid Waste"  (SW-846).

     Briefly, Method 1311  (TCLP) consists of mixing 100 grams of
sample with an acetic acid extraction fluid in a liquid-to solid
ratio of 20:1.  The sample/extract is then agitated end-over-end
for 18 hours, after which it is filtered through a 0.7 urn filter
and the filtrate analyzed for the species found in Table 1 of 40
CFR 261.24 (attached).

     Given the low probability of their occurrence in incinerator
ash, it is recor -ended that the organic compounds be analyzed for
only in the first 1 or 2 extracts.  Only if one or more organic
compounds are detected should the remaining extracts be routinely
analyzed for the organics.

     Prior to analysis of the extracts using atomic absorption
spectrometry  (AA),  inductively coupled plasma spectroscopy (ICP),
or gas chromatography (GC), the extracts must be prepared using
the appropriate methods. Recommended SW-846 methods are shown in
Figure 2-3B of Chapter Two of SW-846 (attached).

     SW-846 contains several analytical techniques for trace
metal determinations:  ICP, direct aspiration flame atomic
absorption (FAA), graphite furnace atomic absorption (GFAA),
hydride generation atomic absorption (HGAA)  and cold vapor atomic
absorption (CVAA).   Each of these is briefly discussed below in
terms of advantages, disadvantages,  and cautions for analysis of
municipal incinerator wastes and TCLP extracts.

     1.  ICP's primary advantage is that it allows simultaneous
     or rapid sequential determinations of many elements in a
     short time.   The primary disadvantage of ICP is interference
     by background radiation from other elements and the plasma
     gases.  Although all ICP instruments use high-resolution
     optics and background correction to minimize these
     interferences, analysis for traces of metals in the presence
     of a large excess of a single metal is difficult.   Examples
     would be traces of metals in a limed (high calcium)  waste.
     ICP and FAA have comparable detection limits (within a
     factor of 4),  except that ICP exhibits greater sensitivity
     for refractory elements (e.g.,  aluminum, barium).   GFAA, in
     general, exhibits lower detection limits than does either
     ICP or FAA.   However, all these techniques have adequate
     sensitivity for determining whether the wastes pass or fail
     the TC.

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2.  FAA determinations, as opposed to ICP determinations,
are normally completed as single-element analyses and are
relatively free of interelement spectral interferences.
Either a nitrous oxide-acetylene or an air-acetylene flame
is used as an energy source for dissociating the aspirated
samples into the free atomic state, making analyte atoms
available for absorption of light.  In the analysis of some
elements, the temperature or type of flame used is critical.
If the proper flame and analytical conditions are not used,
chemical and ionization interferences can occur.

3.  GFAA replaces the flame with an electrically heated
graphite furnace.  The furnace allows for gradual heating of
the sample in several stages. Thus, the processes of
dissolution, drying, decomposition of organic and inorganic
molecules and salts, and formation of atoms, which must
occur in FAA or ICP -' i a few milliseconds,  may be allowed to
occur over a much longer time and at a controlled
temperature in the furnace.  This allows an experiences
analyst to remove unwanted matrix modifiers.  The major
advantage of this techniques is that it affords extremely
low detection limits.  It is the easiest to perform on
relatively clean samples.  Because this technique is so
sensitive,  interferences can be a real problem with complex
matrices.  Finding the optimum combination of digestion,
heating times and temperatures,  and matrix modifiers can be
a challenge.

4.  HGAA uses a chemical reduction to reduce and separate
arsenic or selenium selectively from a sample digest.   The
techniques therefore has the advantage of being able to
isolate these two elements from complex samples that may
cause interferences for other analytical procedures.
However,  significant interferences have been reported when
any of the following is present:   an easily reduced metal
(copper,  silver,  mercury); a high concentration (>200  mg/L)
of a transition metal;  or an oxidizing agent (oxides of
nitrogen)  remaining after sample digestion.

5.  CVAA uses a chemical reduction to reduce mercury
selectively.   the procedure is extremely sensitive but is
subject to interferences from some volatile organics and
sulfur compounds.

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f nvtoonuwntol Protection Agency
                              §261.30
quantity sufficient to present a danger
to human health or the environment.
  (5) It is a cyanide  or sulflde bearing
waste which, when exposed to pH con-
ditions between 2 and 12.5, can generate
toxic gases, vapors or fumes in a quan-
tity sufficient to present a danger to
human health or the environment.
  (6) It is capable of detonation or ex-
plosive reaction if it is subjected to a
strong  initiating source  or if heated
under confinement.
  (7) It is readily capable of detonation
or explosive decomposition  or reaction
at standard temperature and pressure.
  (8) It is a forbidden explosive as de-
fined in 49 CFR 173.51, or a  Class A ex-
plosive as defined in 49 CFR 173.53 or a
Class B explosive as defined in 49 CFR
173.88.
  (b) A solid waste  that exhibits the
characteristic   of  reactivity  has the
EPA Hazardous Waste Number of D008.
[45 FR  33119, May 19, I960, aa amended at 55
FR 22684, June 1. 1990]

$261.24  Toxicity characteristic.
  (a) A solid  waste  exhibits the char-
acteristic of toxicity if, using the test
methods  described  in appendix  n or
equivalent methods  approved  by the
Administrator under the procedures set
forth in §§260.20 and 260.21.  the extract
from a representative sample  of the
waste  contains any of the  contami-
nants  listed in table  1 at the concentra-
tion equal to  or greater than the  re-
spective  value  given in   that table.
Where the waste contains less than 0.5
percent filterable solids,  the waste it-
self, after filtering using the methodol-
ogy outlined  in appendix n, is consid-
ered to be the  extract for the  purpose
of this section.
   (b) A solid waste that  exhibits  the
characteristic of toxicity has the EPA
Hazardous Waste Number specified in
Table I which corresponds to the toxic
contaminant causing  it to be hazard-
ous.

TABLE  1—MAXIMUM CONCENTRATION OF CON-
   TAMINANTS FOR THE Toxicmr  CHARACTERIS-
   TIC
TABLE 1—MAXIMUM CONCENTRATION OF CON-
  TAMH4ANTS FOR THE TOXIOTY CHARACTERIS-
  TIC—Continued

EPAHW
No.'

0004

Contaminant

Arsanc 	 _ 	

CAS No.'

7440-38-2
Raov
latory
Laval

0006
0018
0006
DO20
0021
0022
0007
0023
0024
0023
0026
0016
0027
0028
0030
0012
0031
0033
0034
0008
0013
0009
0014
0035
0036
0038
0010
0011
ryvM
001 5



0017
0043
Contamnant
Barium 	
Banzana ,,,,.,.,,... 	 .__
Cadmium 	
Chtordana .. .
Chtorebanzana 	
Chromium _„_....._ 	
O*€faBOl 	 	 r-T-lrlll
m-C/aaol 	 , 	
p-Crwol 	
OMOI
2.4-O .._........—...— ~.
1,4-Oicnlorobaruana -..
2-Oichloroathana 	
2 4-Oinilrotaluana
Endrin 	 	
HaptacNor (and to ag-
enda*.
HayacNorobutadtena ».
Haxachtaroatiana 	
I*!*! 	
Lindana 	 .
Marcury 	
Mathoncninr
Mawyl alnyl katorta »«..
NMrobanzana »....«...».
aniiacnHrapnanoi —
Pyridina 	
Sttanium 	
Sivar 	
Toxapnana 	


z,4.!>-TiKnioropnanoi _.
2,4,5-TP (Sifeax) 	
Vinyl chloride 	
CASNtxt
7440-39-3
71-43-2
7440-43-9
56 23-6
57-74-9
108-90-7
67-66-3
7440-47-3
96-48-7
106-39-4
106-44-6
94-75-7
106-46-7
107-06-2
Tg *K A
121-14-2
72-20-8
76-44-8
87-68-3
67-72-1
7439-92-1
58-89-9
7439-97-6
7"?— J*W»
78-93-3
96-95-3
87-oft-o
110-86-1
7782-49-2
7440-22-4
1 97—1 ° -*
8001-35-2


35- 0O 4
93-72-1
75-01-4
Ragw
latory
Laval
5.0
1.0
5.0
ft 7
05


9 ft
1.0
0.2
  1 Hazardout waste numbar.
  z Chemical at»liaU» sarvica numbar.
  3Quan«alion limrt a graatar than tha calcUatad ragulatory
 (aval. Tha quamWabon limit tharatora bacomas tha
  4 If o-, m-t and p-Crasol concantrabons cannot ba drftoran-
 tiatad, tha totaJ enact (0026) i
itratan a usad. Tha ragu-
 latory (aval of total craaoi « 200 mgA.

 [55 FR 11862, Mar. 29, 1990, as amended at 55
 FR 22684, June 1, 1990; 55 FR 26987, June 29,
 1990]

    Subport D—Lists of Hazardous
                Wastes

 §261.30 General.
   (a) A solid waste is a hazardous waste
 if it is listed in this subpart, unless it
 has been excluded from  this list under
 §§260.20 and 260.22.
   (b) The Administrator will indicate
 his basis for listing the classes or types

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                                FIGURE 2-3B.
          RECOMMENDED SW-846 METHODS OF ANALYSIS FOR TCLP LEACHATES
                           I  Sample  I
                              TCLP

1
3010

1
7470
Hg




3510
Neutral

1
8240
8260
Volatile
Orqanics

1
3510
(Acidic
and
Basic)

1
8150
8151
Herbic-
ides
   6010
Ba -


Cr -


Ag -
- As


- Cd


- Pb


- Se
                                  TWO  - 49
                                                             Revision 2
                                                          November 1992

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                                                    D!
              QUALITY ASSURANCE AND QUALITY CONTROL
     Appropriate use of data generated under the great range of
analytical conditions encountered in waste characterization
requires reliance on the quality control practices incorporated
into the various testing methods and sampling procedures.  The
Agency has, in many cases, issued approved methods for sampling
and analysis operations fulfilling regulatory requirements.
However, the mere use of approved methods does not guarantee
accurate results.  Inaccuracies can result from many causes,
including unanticipated matrix effects, equipment malfunctions,
and operator error.  Therefore, the quality control component of
each method is indispensable.

     To ensure that the test data used to evaluate the ash are of
known and appropriate quality, all activities associated with
sampling and measurement should be conducted under strict quality
control.  Prior to initiating a sampling/testing prograr
facilities should prepare a detailed quality assurance project
plan describing the steps and controls to be followed.  In
addition, a knowledgeable person should be appointed to oversee
the program to insure that all procedures are followed.  For more
information on preparing and implementing quality assurance
programs, see Chapter One of the Third Edition of SW-846.
                                8

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                                                    DRAFT
                         DATA EVALUATION
     In evaluating the data to determine whether or not  the ash
passes or fails the TC, use the following approach (see  attached
Tables 9-1 and 9-2 of Chapter Nine of SW-846 for statistical
formulas to use in the following calculations):

     1.  Determine the mean TC concentration (x)  of the  fourteen
     eight-hour composite samples for each regulated analyte
     (equation 2a).

     2.  Determine the standard deviation (s)  of the data
     employed to calculate the mean (i.e.,  the individual
     composite extract results) (equations 3a and 4).

     3.  Determine the upper bound of the 90 percent (one-sided)
     confidence interval for the mean for each analyte  (equation
     6) .

     4.  If the upper bound of the interval is below the
     applicable regulatory threshold for all analytes listed in
     40 CFR 261.24,  then the waste passes the TC.   If the upper
     bound of the interval is above the applicable regulatory
     threshold for any analyte listed in 40 CFR 261.24,  then the
     waste fails the TC.

     5.  Given the variability inherent in the ash generation
     process, facilities should recharacterize their ash at least
     four (4) times each year to insure that accurate
     characterization is obtained.  In determining how often to
     recharacterize the ash, the generator should consider all
     facility-specific and external factors that could cause the
     ash properties to vary.  These factors include changes in
     the composition of the waste (e.g.,  new types of industries
     moving into the area, institution of recycling programs in
     the collection area, seasonal changes affecting population
     or waste composition); changes in plant design (e.g.,
     addition of dry scrubber, addition of quench tank);  and
     significant changes in plant operating conditions  (e.g.,
     increase in combustion time or temperature,  change  in lime
     utilization rate).
                           REFERENCES

1.  Test Methods for Evaluating Solid Waste,  Physical/Chemical
Methods, (SW-846),  Third Edition,  US EPA,  Washington, DC, August,
1993.

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TABLE 9-1.  BASIC STATISTICAL TERMINOLOGY APPLICABLE TO SAMPLING PLANS FOR SOLID WASTES
   Terminology
Symbol
Mathematical equation
(Equation)
   Variable (e.g., barium
   or endrin)

   Individual measurement
   of variable
   Mean of all possible
   measurements of variable
   (population mean)

   Mean of measurements
   generated by sample
   (sample mean)
                                                     N
                                                     E
                           with N « number of
                           possible measurements
              Simple random sampling and
              systematic random sampling
     n
     E x
     1=1
      n
                                                       1
                                                         ,  with n = number of
                                                           sample measurements
                                        (1)
                                                     (2a)
                                               Stratified random sampling
                      r
                      E
                                                               with X|< = stratum     (2b)
                                                               mean and W|< - frac-
                                                               tion of population
                                                               represented by Stratum
                                                               k (number of strata
                                                               [k] range from 1 to r)
    Variance  of sample
               Simple  random sampling and
               systematic random sampling
                    n  „    n
                                                     E x
                          - (E x,)2/n
                            1=1 1
                                                        n - 1
                                                                                     (3a)
                                               Stratified random sampling

                                                *%    i     o          *i
                                                     E
                                                    k-1
                               with sr = stratum
                               variance and WV =
                               fraction of population
                               represent by Stratum k
                               (number of strata [k]
                               ranges from 1 to r)
                                       (3b)
                                        NINE - 2
                                                                    Revision      0
                                                                    Date  September 1986
                                             10

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TABLE 9-1.  (Continued)
   Terminology
Symbol
Mathematical equation
(Equation)
   Standard deviation of
   sample

   Standard error
   (also standard error
   of mean and standard
   deviation of mean)
   of sample
  sx
                = 17
s	L.
 x   Jn
       (4)


       (5)
   Confidence Interval
   for /»a
 CI
« - * ± t.20 s7, with t.go
                      "led
                                obtained from
                                Table 2 for
                                appropriate
                                degrees of freedom
       (6)
   Regulatory threshold3
 RT
Defined by EPA  (e.g., 100 ppm for      (7)
barium 1n elutriate of EP toxldty)
   Appropriate number of
   samples to collect from
   a  solid waste  (financial
   constraints not considered)
                                    RT - x
                                       (8)
 •  Degrees of  freedom
 df
df = n - 1
       (9)
      aThe  upper limit  of  the  CI  for /i  1s  compared with the applicable regulatory
 threshold  (RT)  to  determine 1f a solid waste  contains the variable  (chemical
 contaminant)  of concern at a  hazardous level.  The contaminant of concern 1s not
 considered to be present  1n the  waste  at  a  hazardous level 1f the upper limit of the CI
 1s  less  than  the applicable RT.   Otherwise, the opposite conclusion 1s reached.
                                        NINE - 3
                                                                   Revision      0
                                                                   Date  September 1986
                                          11

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       TABLE 9-2.  TABULATED VALUES OF STUDENT'S "t" FOR EVALUATING
                               SOLID WASTES
Degrees of
freedom (n-l)a
1
2
3
4
5
6
7
8
9
10
11
12 ,
13
14
15
16
17
18
19
.20
21
22
23
24
25
26
27
28
29
30
40
60
120

Tabulated
"t" valueb
3.078
1.886
1.638
1.533
1.476
1.440
1.415
1.397
1.393
1.372
1.363
1.356
1.350
1.345
1.341
1.337
1.333
1.330
1.328
1.325
1.323
1.321
1.319
1.318
1.316
1.315
1.314
1.313
1.311
1.310
1.303
1.296
1.289
1.282
     aDegrees of freedom (df) are equal to the number of samples  (n)
collected from a solid waste less one.

     tabulated "t" values are for a two-tailed confidence Interval
and a probability of 0.20 (the same values are applicable to a one-tailed
confidence Interval and a probability of 0.10).
                                  NINE - 4
                                                         Revision      0
                                                         Date  September 1986

                                   12

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                                                     D:
                            APPENDIX A
               DEFINITIONS  OF TERMS APPROPRIATE TO
                 ASH GENERATION/CHARACTERIZATION

MSW:  Municipal  Solid Waste including domestic solid wastes,
commercial  solid wastes,  light demolition and renovation waste
and non-hazardous  industrial wastes usually removed from
dumpsters.

Bottom Ash:   Coarse, relatively dense  (40-70 lbs/ft3 dry)  ash
remaining on  the furnace  grate after controlled combustion of MSW
 (usually less than 2" OD).

Clinkers:   Large (greater than 2" OD) glass-like fused
noncombustible materials  which form during the high temperature
combustion  on the  furnace grate and are discharged from the
furnace in  this  fused, agglomerate form.

Slagging:   Usually larger (greater than 6" OD) fused and layered
silicates and semi-volatile metals which build up on the
refractory  and convective surfaces of the furnace internal
fireside walls and either break off during furnace operation or
are manually  removed during furnace and boiler cleaning.

Riddlings:  Sand-like material which passes down through the
furnace grate system during normal facility operation.  This
material is quite  often silica-based and noncombustible.

Non-Combustibles:  Variable sized materials which are only
partially volatile at their surfaces and maintain a majority of
their structural integrity  through the combustion process.
Examples are  car wheels,  springs, machine parts,  frames, rocks,
and bottle  tops.

Soot Blows:   Very  fine  (10  micron +) agglomerated particles and
particle-entrapped gases  which collect by condensation,
impingement and/or attachment onto boiler tube faces,  usually in
boiler regions where gas  velocities suddenly decrease or form
eddy turbulent flow.  These layered materials are removed during
boiler maintenance usually  by high pressure hydraulics or steam
spargers or by vibratory, pneumatic or impact devices.

Fly Ash:  Light  (usually  less than 20 lbs/ft3  dry weight basis)
flue gas-entrainable particle material carried off the furnace
grate during  combustion by  the updrafting of underfire air.
Depending on  the facility design, these flue gas entrained
particles, volatilized elements/compounds,  and gaseous fractions
will be partially  collected in post combustion flyash hoppers
mostly in solid  particle  form,  with some smaller gaseous
fractions entrapped in gaseous form.

Scrubber By-Product:  Unreacted lime and lime-gas reaction
products resulting from the injection of lime prior to an
ESP/Cyclone/FF;   used primarily for control  of acid gases.   By-

                               13

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                                                   u ,  <...   .." .:


products include CaSO3,  CaSO4, CaCl2, CaF2,  unreacted lime  (CaO or
Ca(OH)2)  and a small amount of solid-to-solid phase reaction
compounds.


     The most common collection points for fly ashes and soot
blows are as follows:

     1.  Superheater hopper:  Similar to boiler hopper and many
     times discharged directly back onto the furnace grate.
     Collects flyash in the superheater section of the boiler.

     2.  Boiler hopper:  Usually collects heavier particles in
     the main boiler tubed sections; often discharged onto
     bottom-ash.

     3.  Economizer hopper:  Collects flyash in the economizer
     sec xon of the boiler.  This is sometimes collected separate
     from the bottom ash within the plant process.

     4.  ESP/cvclone/FF hoppers:  Three possible particulate
     collection devices, Electrostatic Precipitators (ESP),
     cyclone collection devices and fabric filters (FF) are used
     primarily to reduce fine particle emissions to the
     atmosphere.  These devices usually account for 75% of the
     flyash weight basis collected by all hoppers, with the
     boiler, superheater and economizer accounting for the
     remaining 25%.
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