am
tary
 and
  &4,'i * .<*;•'
fill"
  1''

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     Sanitary Landfill
Design and Operation
          This report (SW-65ts) was written by
        DIRK R, BRUNNER and DANIEL J. KELLER
            ENVIRON.^?-:'•; P^~rcT  ,
                         "•• *•• •i*'—-jltO
     U.S. ENVIRONMENTAL PROTECTION AGENCY
                1972

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          An environmental protection publication

       in the solid waste management series (SW-65ts)

For sale by the Superintendent of Documents, U.S. Government Printing Office
              Washington, D.C. 20402 - Price 65 cents
                    Stock Number 5502-0085

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foreword
    Sanitary Landfill Design and Operation is a state-of-the-art treatise. It
not only describes the known in sanitary landfill technology,  it also indicates
areas in which research is needed.
    This  publication represents the combined efforts of many individuals
within the Federal solid waste management program, other Federal agencies,
State and local governments, private industry,  and universities.
    It is the hope of the U.S. Environmental Protection Agency that planners,
designers, operators, and government officials  will use this  document as a
tool to help overcome the poor land disposal practices that are evident today.

                            —SAMUEL HALE, JR.
                              Deputy Assistant Administrator
                              for Solid Waste Management
                                           III

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ChaPter                                                  page

  1.       THE SOLID WASTE PROBLEM	   1

  2.       SOLID WASTE DECOMPOSITION 	   3
               Leachate
               Contaminant Removal
               Decomposition Gas

  3.       HYDROLOGY AND CLIMATOLOGY	  10
               Surface Water
               Groundwater

               Climatology

  4.       SOILS AND GEOLOGY	  13
               Soil Cover

               Land Forms

  5.       SANITARY LANDFILL DESIGN	  20
               Volume Requirements
               Site Improvements
                    Clearing and grubbing
                    Roads
                    Scales
                    Buildings
                    Utilities
                    Fencing
               Control of Surface Water
               Groundwater Protection
               Gas Movement Control
                    Permeable methods
                    Impermeable methods
               Sanitary Landfilling Methods
                    Cell construction and cover material
                    Trench method
                    Area method
                    Combination methods
               Summary of Design Considerations

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Chapter                                                        page

  6.         SANITARY  LANDFILL OPERATION	  31
                 Hours of Operation
                 Weighing the Solid Waste
                 Traffic Flow and Unloading
                 Handling of Wastes
                      Residential, commercial, and industrial plant
                        wastes
                      Bulky wastes
                      Institutional wastes
                      Dead animals
                      Industrial process wastes
                      Volatile and flammable wastes
                      Water and wastewater treatment plant sludges
                      Incinerator fly ash and residue
                      Pesticide containers
                      Animal manure
                      Radioactive wastes and explosives
                 Placement of Cover Material
                      Daily cover
                      Intermediate cover
                      Final cover
                 Maintenance
                 Weather  Conditions
                 Fires
                 Salvage and Scavenging

  7.         EQUIPMENT	  39
                 Equipment Functions
                      Waste handling
                      Cover material handling
                      Support functions
                 Equipment Types and Characteristics
                      Crawler machines
                      Rubber-tired machines
                      Landfill compactors
                      Scrapers
                      Dragline
                      Special-purpose equipment
                      Accessories
                      Comparison of characteristics

                 Size of Operation
                      Single-machine sites
                      Small sites
                      Multiple-machine operation
                 Costs
                      Capital Costs
                      Operating and maintenance costs

  8.         COMPLETED SANITARY LANDFILL	  48
                 Characteristics
                      Decomposition
                      Density
                      Settlement
                      Bearing capacity
                      Landfill  gases
                      Corrosion
                 Uses
                      Green area
                      Agriculture
                      Construction
                      Recreation
                 Registration

                                              vi

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Chapter
  9.
MANAGEMENT  	
    Administrative Agency
          Municipal operations
          Special districts
          County operations
          Private operations
    Administrative Functions
          Finances
          Operational cost control
          Performance evaluation
          Personnel
          Public relations
BIBLIOGRAPHY  	
page
52
             ACKNOWLEDGMENTS
56
59
                                          List of tables
                                                                           page

  Table  1    Composition of initial leachate from municipal solid waste             4
  Table  2    Groundwater quality near a landfill                                 6
  Table  3    Landfill gas composition                                          8
  Table  4    Suitability of soil types as cover material                            14
  Table  5    Soil classification and characteristics pertinent to sanitary landfills     17
  Table  6    Application of cover material                                     35
  Table  7    Insecticides for fly control                                        37
  Table  8    Accessories for landfill equipment                                 44
  Table  9    Performance characteristics of landfill equipment                    45
  Table 10    Landfill equipment needs                                        45
  Table 11    Machine capital cost                                             46

                                          List of figures
                                                                          Page

  Figure  1   Concentration  of cations in leachate                                5
  Figure  2   Concentration  of anions in leachate                                 6
  Figure  3   Gas production from an experimental  sanitary landfill                 7
  Figure  4   Leachate and infiltration movements affected by soil and bedrock     13
  Figure  5   Textural classification chart                                       16
  Figure  6   Yearly volume of waste from a community of 10,000                20
  Figure  7   Daily volume of waste from large communities                      21
  Figure  8   Daily volume of waste from small communities                      21
  Figure  9   Special litter-control fences near a landfill's working face            23
  Figure 10   Diversion ditch to transmit upland drainage around a landfill         23
                                             VII

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              List of figures (continued)
                                                                           page
Gravel vents or gravel-filled trenches to control lateral gas movement   25
Figure 11
Figure 12    Gases vented via pipes inserted through top cover                    26
Figure 13    Clay as a liner or curtain wall to block underground gas flow          26
Figure 14    Cell construction and cover material                                27
Figure 15    Trench method of sanitary landfilling                              28
Figure 16    Area method of sanitary landfilling                                28
Figure 17    Slope or ramp method of sanitary landfilling                        29
Figure 18    Reduction of cushioning and bridging on working face of slope       33
Figure 19    Crawler dozer used for grading                                    40
Figure 20    Crawler loader with a general-purpose bucket                       41
Figure 21    Crawler loader with a multiple-purpose bucket                      41
Figure 22    Rubber-tired dozer                                               41
Figure 23    Rubber-tired loader                                              41
Figure 24    Steel-wheeled landfill compactor                                   42
Figure 25    Landfill compactor wheels                                        43
Figure 26    Scrapers                                                        43
                            vru

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the   solid   waste   problem
     The Nation  is  emerging from  a prolonged
period  in which  it neglected  solid  waste  manage-
ment, and it is  becoming increasingly aware  that
our  present  solid  waste storage,  collection,  and
disposal  practices  are inadequate.  Much  of  this
awareness has been brought about by active cam-
paigns directed against air and water pollution and
has resulted  in a  third  campaign—the abatement of
land pollution.
     The magnitude of the problem  can be  appre-
ciated when  we consider that the Nation produced
250 million  tons of residential,  commercial,  and
institutional  solid wastes in 1969. Only 190  million
tons were collected. Much of the remainder found
its way to scattered heaps across  the countryside,
was  left to accumulate in backyards and vacant lots,
or was strewn along our roadways.  To compound
the problem, an estimated 110 million tons of indus-
trial wastes and nearly 4 billion tons of mineral and
agricultural wastes were generated.
     Because of  our affluence and  increasing popu-
lation, these quantities are expected to increase. In
1920,  solid  waste  collected  in our urban areas
amounted to only 2.75 Ib per capita. In 1970, the
figure stood  at over 5 Ib, and it  is estimated  that
it will reach 8 Ib by 1980.
     Solid waste processing and disposal practices
are grossly  inadequate for today's needs.  Only  6
percent of land disposal operations and 25  percent
of incinerator facilities were considered adequate in
the  1968 National Solid  Wastes  Survey.1
     This inadequacy  is the  result of lack of plan-
ning and  financing and, until  recently, public apathy
with regard to  our environment. There has  been far
too little  effort made to locate and reserve suitable
areas for land disposal operations in anticipation
of community growth.  Consequently,  it is becoming
more and more difficult to locate disposal  sites in
urban areas.  This directly affects disposal  costs,
because hauling expenses to a suitable landfill site
increase or a  more expensive alternative method of
processing  is required prior to disposal.
     More than 90  percent of our Nation's solid
waste is directly  disposed  of  on land, the vast
majority of it  in an  unsatisfactory manner.  Open
and  burning  dumps, which are  all  too common,
contribute to  water  and air pollution and p'rovide
food, harborage, and  breeding grounds for insects,
birds, rodents,  and  other carriers of  disease. In
addition, these dumps are unsightly and very often
lessen the value of nearby land and residences. In
response to an aroused  public, legislation has been
passed on  the local, State, and Federal levels to aid
the development of  satisfactory  disposal practices
and to plan for all aspects of solid waste manage-
ment. The development and implementation of such
plans will, however,  require the  combined support
of all citizens, industry, and government.
     An acceptable alternative to the present poor
practices of land  disposal is the  sanitary landfill.
This alternative involves the planning and applying
of sound  engineering principles  and  construction
techniques. Sanitary  landfilling  is an  engineered
method  of  disposing of solid wastes on land  by
spreading  them in thin layers,  compacting  them
to the smallest practical volume,  and covering them
with soil each working day in a manner that protects
the environment. By definition, no burning of solid
waste occurs at a  sanitary landfill. A sanitary land-
fill is not only an acceptable and  economic method
of solid waste disposal, it is also an excellent way
to make  otherwise  unsuitable  or marginal land
valuable.
     Thorough planning and the application of sound
engineering principles to all stages of site selection,
design, operation,  and completed use will result in
   470-406 O - 72 - 2

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a successful and efficient sanitary landfill. In order
to meet this  objective,  it is  also essential to have
an understanding of solid waste decomposition pro-
cesses—how  the  many variables  may  affect  the
decomposition  rate, decomposition  products, and
how  these factors may influence the  environment.
In essence, these relationships determine the physi-
cal stability of the fill  and its potential  to produce
such  environmental  problems  as  uncontrolled  gas
generation and  movement  and  water  pollution.
Although  these  relationships  are not fully  under-
stood,  sufficient  knowledge is available  to  enable
us to recognize potential problems and to plan and
design  sanitary  landfills that will  not  harm  the
environment.
     The final selection of a sanitary landfill site,  its
design,  and  its  operation should  be based on  a
systematic,  integrated  study  and an  evaluation  of
all physical conditions,  economics, and social politi-
cal  restraints.
                                            REFERENCE

                1. BLACK, R.  J-, A. J. MUHICH, A. J.  KLEE, H. L  HICKMAN, JR., and  R.  D.
                         VAUGHAN.    The national solid  wastes survey;  an interim report.
                         [Cincinnati],  U.S. Department of Health, Education,  and Welfare,
                         [1968]. 53  p.

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solid   waste   decomposition
     A knowledge of solid waste decomposition pro-
cesses and the many influences they exert is essen-
tial to proper sanitary landfill site selection and
design.
     Solid wastes deposited  in a  landfill degrade
chemically and biologically to produce  solid, liquid,
and gaseous products.  Ferrous and other metals are
oxidized;  organic and inorganic wastes are utilized
by microorganisms through  aerobic and anaerobic
synthesis. Liquid waste products of microbial deg-
radation,  such as organic acids, increase chemical
activity within the fill. Food wastes degrade quite
readily,  while  other materials, such  as plastics,
rubber,  glass  and  some  demolition  wastes, are
highly  resistant  to  decomposition. Some factors
that affect degradation are the heterogeneous char-
acter of the wastes, their physical, chemical, and
biological properties, the availability of oxygen and
moisture within the fill, temperature, microbial pop-
ulations,  and type  of synthesis. Since the solid
wastes usually form  a  very  heterogeneous mass of
nonuniform size and variable composition and other
factors are complex, variable,  and difficult to con-
trol,  it is  not possible to accurately  predict  con-
taminant  quantities and production  rates.
     Biological activity  within a landfill  generally
follows a set pattern.  Solid  waste  initially decom-
poses aerobically, but as the oxygen supply is ex-
hausted, facultative  and anaerobic  microorganisms
predominate and produce methane gas,  which is
odorless and colorless. Temperatures   rise to the
high mesophilic-low thermophilic range  (60 to 150F)
because of  microbial  activity.  Characteristic  pro-
ducts of aerobic decomposition of waste are carbon
dioxide,  water,  and nitrate.  Typical  products of
anaerobic decomposition of waste are methane, car-
bon dioxide,  water,  organic  acids,  nitrogen,  am-
monia, and sulfides of iron, manganese, and  hy-
drogen.

Leachate

     Groundwater or infiltrating surface water mov-
ing through  solid  waste can produce  leachate, a
solution containing  dissolved and finely suspended
solid matter and microbial waste products. Leachate
may leave the fill at the ground  surface as a spring
or percolate through the soil and rock that underlie
and surround  the waste.
     Composition of leachate is important in deter-
mining its potential  effects on the quality of nearby
surface water and  groundwater. Contaminants car-
ried in leachate are dependent on solid  waste com-
position and on the simultaneously occurring physi-
cal, chemical,  and  biological activities within the
fill. Identification of leachate composition has been
the object of several laboratory  lysimeter and field
studies.1'6
     The chemical and biological characteristics of
leachate were determined in two studies conducted
over a period  of time with solid waste of the same
general type at both sites (Table 1). The data exhibit
a significant range of values. As an example, pH of
the leachate  investigated in study A was  found to
vary between  6.0  and 6.5' while pH  in  study  B
varied between 3.7  and 8.5.2 Chloride varied from
96 to 2,350  mg per liter in study A  and from  47
to 2,340  in study B. Although the leachates for the
two studies were similar in many  respects,  there
were differences which  further  indicate the varia-
bility of  leachate composition  with time  for indi-
vidual sites and between sites. For example, mean
sulfate concentrations  were 614 mg per liter for
study A,  ranging from 730 near the start of the

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                     TABLE 1
     Composition of Initial  Leachate*
       from Municipal Solid Waste
Component
                    Study A1
Study B*
                  Low      High     Low       High
pH                 6.0        6.5     3.7       8.5

Hardness, CaC03    890      7,600    200       550

Alkalinity, CaC03    730      9,500

Ca               240      2,330

Mg                64       410

Na                85      1,700    127     3,800

K                 28      1,700

Fe (total)            6.5      220      0.12   1,640

Ferrous iron         8.7t       8.7t

Chloride            96      2,350     47     2,340

Sulfate             84       730     20       375

Phosphate           0.3       29      2.0      130

Organic-N            2.4      465      8.0      482

NH4-N              0.22     480      2.1      177

BOD            21,700    30,300

COD                               809    50,715

Zn                                  0.03     129

Ni                                  0.15      0.81

Suspended solids                      13    26,500
    ** Average composition,  mg per liter of first  1 3 liters of
     leachate per cubic foot of a compacted, representative,
     municipal solid waste.
    t One determination.
test to  84 near the conclusion.  Sulfate concentra-
tions in study B averaged 152 mg per liter, ranging
from 375  at  the  beginning of sampling to 20 at
the  conclusion.
     The quantity of contaminants  in leachate from
a completed fill where no more waste is  being  dis-
posed of  can be  expected  to decrease with time.
Only a few studies have attempted to determine the
effect of long term leaching of solid waste.1'3 Much
more research is  needed in the laboratory  and in
the field to adequately describe this  phenomenon.
The  limited data  available indicate  a  removal of
large quantities of contaminants by leaching during
active stages of decomposition, and a slackening off
of removal as the fill stabilizes  (Figures  1,  2).  If
the fill is considered as a mass of material contain-
ing  a  finite  amount  of  leachable  material,  then
depending  on the  removal  rate, leaching  should
eventually  cease.
     The types and quantities of contaminants that
enter the  receiving  water and  the  ability of that
water to assimilate these  contaminants will  deter-
mine the degree of leachate control needed. In some
cases  it may be  established that introduction of
leachate will not upset the ecology or  usefulness of
the receiving water. Careful examination of dilution
and  oxygen demand criteria  of the  stream can be
useful  tools in showing the  ability of a stream to
assimilate  leachate.  In  all  cases,  water  quality cri-
teria and the laws and ordinances of Federal,  State,
and  local  agencies  pertaining  to water  pollution
must be followed.
     Some investigators believe that even in a sani-
tary landfill,  leachate  production  is inevitable  and
that some leachate will  eventually  enter surface
water or groundwater. This has not been proven but
neither has the opposite view. The present philos-
ophy held by the Office of Solid Waste Management
Programs,  most State  solid waste control agencies,
and  many experts in the field is that through sound
engineering and  design,  leachate production  and
movement  may be prevented or  minimized to the
extent that it will not create a water pollution prob-
lem. The most obvious means of controlling leachate
production and movement  is to prevent  water from
entering the fill  to the greatest extent practicable.

Contaminant Removal

     Leachate percolating  through soils underlying
and  surrounding the solid waste  is subject to puri-
fication (attenuation)  of the  contaminants  by ion
exchange,  filtration,  adsorption,  complexing, pre-
cipitation, and biodegradation. It moves either as an
unsaturated flow if the voids in soil are only partially
filled with water or as a saturated flow  if they are
completely filled. The type of flow affects the mech-
anism  of attentuation, as do soil particle  size  and
shape  and  soil composition.
     Attentuation  of  contaminants flowing  in  the
unsaturated zone  is generally  greater than in  the
saturated  zone because there is  more potential for
aerobic degradation,  adsorption,  complexing,  and
ion exchange of organics, inorganics, and microbes.
Aerobic degradation of organic  matter  is  more rapid
and  complete  than anaerobic degradation. Because
the  supply of oxygen  is  extremely  limited in  sat-

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      2500
      2000-
       1500
   q
   5
   |   1000
   UJ
   u
   o
   u

   B    500
                Calcium
                 Sodium
             Magnesium o
                                                   -o--o
                       200         400         600         800         1000        1200
                                      WATER APPLIED AFTER SATURATION (gallons)
                                                                                               1400
                        13
        217             306     350
ELAPSED TIME AFTER SATURATION (days)
                                                                                   419
                                                                                               488
                 Figure.  1   Concentration of cations in leachate; adapted from Reference 1.
urated flow, anaerobic degradation prevails. Adsorp-
tion and ion exchange are highly dependent on the
surface area of the  liquid and solid  interface. The
surface area to flow volume ratio is greater in an
unsaturated flow than in a saturated flow.
     Leachate  travel in  the saturated zone is  pri-
marily controlled by  soil  permeability and hydraulic
gradient, but a limited amount of capillary diffusion
and dispersion  do occur.  The leachate is diluted very
little in groundwater unless a natural geologic mix-
ing basin  exists.  Leachate movement  will  closely
follow  the  streamlines of  groundwater flow.
     Information on  leachate travel  in  the unsat-
urated zone is lacking.  Most of  the studies made
of residential  and industrial wastewaters traveling
through  the unsaturated  zone  indicate  that  the
organic and microbial   removal  level  achieved  is
very good.  As an example,  when  a  citrus  liquid
waste was  applied to the ground  surface, COD was
reduced from  5,000 mg per liter to less than 100
in the  top  3 ft of soil.7  However,  the rate and  fre-
quency at which the  waste liquid  is applied and the
              type of soil have great influence on attenuation effi-
              ciency.  Nitrification  can also occur  in  the  unsat-
              urated soil  zone and produce  nitrate  and  nitrite
              from ammonia-nitrogen. A water that was bacteriolo-
              gically safe,  according to USPHS Drinking Water
              Standards for the coliform group, was obtained  by
              percolating settled  domestic waste water through
              at least 4 ft of a fine, sandy loam soil.8 This last
              study is especially important since pathogens  have
              been  detected  in solid waste and leachate.'il0
                   Travel  of  leachate in the saturated zone has
              been  monitored  by several  investigators,4'5'" but
              more research is  needed to clearly define its signifi-
              cance. Results obtained  so  far indicate  that the
              distance the contaminants travel depends on the
              composition of the  soil,  its  permeability,  and the
              type  of contaminant.  Organic  materials  that are
              biodegradable do not travel far,  but  inorganic ions
              and  refractive organics can travel  appreciable dis-
              tances. Some inorganic contaminants from a  dump
              located in an abandoned gravel pit have been traced
              for 1,200 ft.4 Contaminant movement was through

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  O)

 Z
 O
 u
 Z
 O
 (J
 Z
 O
      2500
      2000
1500
1000
        500
                Chloride
                 Sulfate <
                                                     o(XX>	O-QT,,—O-Oo	Orv-0	O-
                                                                    OQ	OQ-O	O—O
                200         400         600         800        1000
                                WATER APPLIED AFTER SATURATION (gallons)
                                                                                   1200
                                                                                                1400
                        13           95          217             306      350

                                         ELAPSED TIME AFTER SATURATION (days)

                  Figure 2.  Concentration of anions in leachate; adapted  from Reference 1.
                                                                             419
488
a highly porous glacial alluvium. Another study indi-
cates that the rate of movement through some soils
is so slow that the full impact of contaminant  travel
may not be realized for many years.5 If contaminant
travel is slow, the release  of contaminants  to an
aquifer would also be slow.
     Inorganic materials appear to be most resistant
to attenuation. This is especially true of chloride ion,
and it serves, therefore, as a good indicator of  leach-
ate movement. Data from monitoring wells surround-
ing a landfill  in Illinois reflected a  sharp increase in
chlorides and  total dissolved solids (Table 2).  Chlo-
ride concentrations  in the  unaffected groundwater
were  18  mg per liter, those in the fill were l,710,v
and those in a monitoring well 150 ft  downstream
of the fill were 248.
     Natural  purification processes have only  a lim-
ited  ability to remove contaminants,  because  the
number of adsorption sites and exchangeable ions
available is finite.  In addition, the processes  are
time dependent—residence time is shortened by high
flow rates. Flow  rates through soils near landfills
                                                                          TABLE 2
                                                     Groundwater Quality  in the
                                                          Vicinity of a Landfill5
Characteristic
Total dissolved solids
PH
COD
Total hardness
Sodium
Chloride
Background
mg/1
636
7.2
20
570
30
18
Fill* Monitor well*
mg/1 mg/1
6,712
6.7
1,863
4,960
806
1,710
1,506
7.3
71
820
316
248
                                                  •" Groundwater quality in a saturated fill and in a monitor-
                                                   ing well located approximately 150 ft downstream from
                                                   the landfill at a depth of 11 ft in sandy, clayey silt.

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 may  be reduced naturally by filtering and settling
 of  suspended contaminants. Porosity and  permea-
 bility of the soil  are then reduced. Thus, additional
 protection against  contaminant travel may be pos-
 sible as  time passes.  (Analysis  of  precipitation,
 flooding,  upland drainage,  and evapo-transpiration
 necessary to determine whether leaching will occur
 at a site is discussed later.)

 Decomposition Gas

      Gas is  produced naturally when solid wastes
 decompose. The  quantity generated in a landfill and
 its composition  depend on the types of solid waste
 that are decomposing. A waste with a  large fraction
 of  easily  degradable  organic  material will  produce
 more gas than one that  consists largely of ash and
 construction  debris. The rate of gas  production  is
 governed  solely  by the  level  at  which  microbial
 decomposition is occurring in the solid waste. When
 decomposition ceases,  gas production  also  ends.
 In  a  field  study  conducted over a 907-day period,
 approximately 40 cu ft  of  gas were  produced per
 cu yd of solid waste.12 Gas production was monitored
 throughout the  duration  of this study  (Figure 3).
 Theoretically,  if decomposition  is carried to comple-
 tion,  each Ib  of  solid waste containing  25 percent
 inerts can produce up to 6.6 cu ft of  gas.
                                                          Methane and  carbon dioxide are  the  major
                                                     constituents of landfill decomposition gas, but other
                                                     gases are  also  present  and some may  impart a
                                                     repugnant odor. Hydrogen sulfide, for example, may
                                                     be generated at  a landfill, especially  if it contains
                                                     a large amount of sulfate, such as gypsum  board
                                                     (calcium  sulfate)  or if brackish water  infiltrates the
                                                     solid waste.
                                                          Limited  studies have been made  on the vary-
                                                     ing composition of landfill gas over a period of time
                                                     (Table  3).  The data indicate that  the percentages
                                                     of carbon dioxide and methane present three months
                                                     after solid wastes were placed in the fill were 88 and
                                                     5, respectively;  four years later the  respective fig-
                                                     ures  were  51 and 48. Very  little  methane is pro-
                                                     duced  during the early  stages of  decomposition
                                                     because aerobic  synthesis prevails.
                                                          Landfill  gas  is important to consider  when
                                                     evaluating the effect a  landfill may have  on the en-
                                                     vironment,  because methane can  explode and be-
                                                     cause mineralization of groundwater  can occur  if
                                                     carbon  dioxide dissolves and forms carbonic acid.
                                                     Methane  is explosive only when present in  air at
                                                     concentrations between 5 and  15 percent.  Since
                                                     there is no oxygen present in a landfill when  meth-
                                                     ane concentrations in  it  reach this  critical  level,
                                                     there is no danger of the fill exploding. If, however,
                                                     methane  vents  into the  atmosphere  (its  specific
         y
    2000
 Q
 o
 a.
 <
 O
o
UJ
>
<
    1500
    1000
     500
                           200       300      400       500      600      700

                               ELAPSED TIME SINCE CELL CONSTRUCTION (days)
                                                                                    800
900
     Figure 3.  Gas production from an experimental sanitary landfill; adapted from Reference 12. Gas production
is from 40 cu yd  of residential solid waste at a density of 634 Ib per cu yd with a moisture content (wet weight)
of 34.6  percent.  Composition  of the  solid waste used, on  a percentage basis: paper  (42.7); grass and garden
clippings (38); plastic (3); glass (5); metal (7); dirt (5).

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            TABLE 3
Landfill Gas Composition1
Time interval since start
of cell completion
(months)
0-3
3-6
6-12
12-18
18-24
24-30
30-36
36-42
42-48
Average
N2
5.2
3.8
0.4
1.1
0.4
0.2
1.3
0.9
0.4
percent
C02
88
76
65
52
53
52
46
50
51
by volume
CH«
5
21
29
40
47
48
51
47
48
gravity  is less than that of air) it may accumulate
in buildings  or other  enclosed spaces  on or close
to a sanitary landfill.
     The potential movement  of gas is, therefore, an
essential element to consider when selecting a site.
It is particularly important if enclosed structures are
built on or adjacent to  the sanitary landfill or  if it
is to be located near existing industrial,  commercial,
and residential areas.
     Gas  permeability of the soils  surrounding the
landfill  can  influence  the movement  of decomposi-
tion gas. A dry soil will not significantly  impair its
flow, but a saturated  soil, such as clay, can  be an
excellent  barrier.  A  well-drained  soil acts  as  a
vent to  gas flow. If cover material acts as a barrier,
then the  landfill gases will  migrate laterally until
they can vent to the atmosphere.  More research  is
needed  to reliably predict rate  and distance of gas
movement.
     Landfill  gas movement  can  be controlled  if
sound  engineering principles  are  applied. Of the
several  methods that have been devised and tested,
permeable vents and  impermeable  barriers are the
two basic types. Both are discussed in Chapter 5.
                                   REFERENCES

       1. California State Water Pollution Control Board.   Report on  the investigation
                 of  leaching of a sanitary landfill. Publication No.  10. Sacramento,
                 1954.  [92 p.]
       2. FUNGAROLI, A.  A.   Pollution of subsurface water by sanitary landfill. (In
                 preparation.)
       3. QASIM. S.  R.    Chemical characteristics of seepage  water  from  simulated
                 landfills.  Ph.D.  Dissertation,  West Virginia  University, Morgantown,
                 1965.  145  p.
       4. ANDERSEN, J.  R., and J. N.  DORNBUSH.   Influence  of sanitary  landfill on
                 ground water quality. Journal American Water  Works Association, 59
                 (4):457^70, Apr. 1967.*
       5. HUGHES, G. M.,  R. A. LANDON, and  R.  N.  FARVOLDEN.   Hydrogeology of
                 solid waste disposal sites in northeastern  Illinois;  a final report on
                 a solid waste  demonstration  grant  project. Washington,  U.S.  Gov-
                 ernment Printing Office,  1971.  154 p.
       6. Ministry of  Housing and Local Government.   Pollution of  water by tipped
                 refuse; report of the  Technical Committee on the  experimental dis-
                 posal of house refuse in wet and dry pits. London, Her Majesty's Sta-
                 tionery Office,  1961.  141  p.
       7. ANDERSON, D. R., W. D. BISHOP, and H.  F. LUDWIG.   Percolation of citrus
                 wastes through soil.  In  Proceedings; 21st Industrial Waste Confer-
                 ence, May 3-5,  1966. Lafayette, Ind., Purdue University, p. 892-901.
       8. California State Water Pollution Control Board.   Field  investigation of  waste
                 water  reclamation in  relation  to ground  water pollution.  Publication
                 No. 6. Sacramento, 1953. 124  p.
       9. WEAVER, L.   Refuse disposal, its significance. In Ground Water Contamina-
                 tion; Proceedings of the 1961 Symposium, Cincinnati, Apr.  5-7,  1961.
                 Technical Report W61-5. Robert A. Taft Sanitary Engineering Center.
                 p. 104-110.
          ' This land disposal site does not meet the standard for a sanitary landfill.

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           10.  COOK,  H. A.,  D.  L CROMWELL,  and  H.  A.  WILSON.    Microorganisms  in
                      household  refuse and seepage  water  from  sanitary landfills.  In  Pro-
                      ceedings;  West Virginia  Academy of Science, 39:107-114.  1967.
           11.  County of Los  Angeles,  Department of County Engineer and  Engineering-
                      Science, Inc.    Development  of construction  and use  criteria  for
                      sanitary landfills; an interim report. Cincinnati,  U.S.  Department  of
                      Health,  Education, and  Welfare, 1969. [267 p.]
           12.  MERZ, R. C., and R. STONE.  Special studies  of a sanitary landfill. Washing-
                      ton,  U.S. Department of Health, Education, and Welfare,  1970. (Dis-
                      tributed by National Technical  Information Service, Springfield,  Va.,
                      as PB-196  148.  240 p.)
470-406 O - 72 - 3

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hydrology   and   climatology
     A major consideration  in selecting the site for
a sanitary landfill and in designing it is the hydrol-
ogy of the area.  To a  large extent,  hydrology will
determine whether  the formation of  leachate will
produce a water pollution  problem.
     When solid  wastes  are  placed  in  a sanitary
landfill, they  may vary tremendously with regard to
moisture content. Wood,  concrete, and  other  con-
struction rubble may have very little, whereas many
food wastes may  be extremely wet. Paper, a major
constituent of solid  waste,  is usually quite low in
moisture. Metals and glass  are also generally  pres-
ent in solid waste but are essentially free of mois-
ture.
     In general, the  moisture content of mixed solid
waste generated by  a community ranges from 20 to
30 percent by weight. (Wide fluctuations  can occur
depending on climatic conditions during storage and
collection.) In this general range, the moisture alone
should not produce leachate provided the solid waste
is fairly well mixed  and has been well compacted.
The water that results from decomposition of the
relatively small amounts of intermixed food wastes
and other moist, readily  degradable organics can
be absorbed  by the  comparatively large amounts of
paper and other dry components present.
     Leachate is not produced until all of the sani-
tary  landfill  or  a  sizable  portion  of  it  becomes
saturated by water entering  it from outside. For this
reason, it is extremely important that a study of the
site hydrology be made. Precipitation, surface runoff
characteristics, evapo-transpiration, and the location
and movement  of groundwater with relation to the
solid waste are the major  factors that should be
considered.
Surface Water

     Surface water that infiltrates the cover soil and
enters the underlying solid waste can  increase the
rate  of waste decomposition  and eventually cause
leachate to leave the solid waste and  create water
pollution  problems. Unless rapid decomposition  is
planned and the sanitary landfill is so designed that
leachate is collected and treated, as much surface
water as is practicable should  be kept from entering
the fill.
     The  permeability of a  soii is the measure of the
ease or difficulty with which water can pass through
it. This is greatly affected  by the texture, gradation,
and structure of the soil and the  degree to which it
has been compacted. Coarse  grained soils (gravels
and sands) are usually much  more permeable than
fine grained soils (silts and clays). However, small
amounts  of silts  and clays  (fines)   in a  coarse
grained  soil  may  greatly decrease  permeability
while cracks  in  fine grained soils  may  do the
opposite.*
     The  quantity of water that can  infiltrate the
soil cover of a sanitary landfill depends not only on
these physical characteristics but also on the resi-
dence time of the surface water. It can be minimized
by: (1) diverting  upland drainage; (2)  grading and
sloping the daily and final  cover to allow for runoff;
(3) decreasing the permeability  of the cover  ma-
terial.
     There have  been few detailed investigations
    •' Specific information on the percentage of water infil-
     trating a particular soil can be obtained from the Soil
     Conservation Service,  U.S. Department of Agriculture.
10

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 made of the quantity  of moisture that can enter a
 sanitary landfill through a  cover and on the amount
 and quality  of  water  that may  leave the fill  and
 enter an aquifer or stream. One investigator claims,
 however, that it is possible to predict the quantity
 of surface  water that will enter the  underlying solid
 waste if the available water storage capacity, quan-
 tity, and frequency  of  water  infiltration,  and  rates
 of evaporation and transpiration for  a cover material
 are known.1 Under ideally controlled laboratory con-
 ditions or at a field test site, this would seem plausi-
 ble, but more studies must  be made of  leaching
 potentials at  operational sanitary landfills. These are
 needed  because the placement of cover soils cannot
 be  rigidly  controlled and  some discontinuities  al-
 ways develop in the structure of a sanitary landfill.
 They derive  from  variations in  soil thickness,  tex-
 ture, and  degree  of compaction  as  well as  from
 slight changes that  occur  in the grade or slope of
 the cover soil when it settles; this  may cause cracks
 or  fissures to  develop. Furthermore,  slight  varia-
 tions in the  amount or intensity  of rainfall,  minor
 changes in vegetation, or other presumably less im-
 portant alterations  of  the  fill's  final surface may
 have major effects on the amount of surface mois-
 ture entering the solid waste.
Ground water

     Groundwater is water that is  contained within
the zone of saturation  of soil  or rock—that  is, all
the  pores  in the  containing  earth  materials are
saturated. This  zone is just beneath the land  sur-
face in many parts of the country and  is on the
surface at many  springs, lakes, and  marshes. In
some areas, notably most of the arid west, the zone
of saturation is  deep in the  ground.
     The  water table  is the  surface where  water
stands in wells  at  atmospheric pressure. In highly
permeable  formations,  such as  gravel, the  water
table is essentially the top of the zone of saturation.
In many fine grained formations, however, capillary
action  causes water to rise above this zone,  and the
inexperienced observer  might  think this  capillary
fringe is part of  the zone.
     The zone  of  saturation commonly is  not con-
tinuous with depth nor does it necessarily have later-
al continuity. In exploring for underground water, a
saturated  zone  may be  found  that yields  water at
a shallow depth, but if  the  exploration  hole is con-
tinued,  dry  material  is encountered at a  greater
depth and then another zone of saturation is found.
Isolated high zones or  lenses of saturated material
are referred to as perched water.  Perched water is
common to glacial soil (till plain) areas  where inter-
stratified  lenses or patches  of porous  sand  and
gravel are underlaid by relatively impervious glacial
clay.
     Because the conditions affecting groundwater
occurrence are so complex, it is essential that the
sanitary landfill site investigation  include an  evalu-
ation  by a qualified groundwater hydrologist. This
is needed not only to  locate the zone of saturation
but also to predict the direction and  rate of flow of
groundwater  and the quality of the aquifer.
     Leachate  from   a   landfill  can  contaminate
groundwater. In order to determine if leachate will
produce a  subsurface pollution  problem, it  is es-
sential that the quality  of the groundwater be es-
tablished and that the aquifer's flow rate and  direc-
tion be determined. Water within the zone of satura-
tion  is not static. It  moves vertically and laterally
at varying  rates, depending on the permeability of
the soil or  rock formation in which it is located and
the external  hydraulic forces acting upon it.
     The movement of  groundwater is  determined
by using a tracer such  as  fluorescein dye  or by
making piezometer readings.  The  estimated  quan-
tity of groundwater flow  is based on the permeabil-
ity of the aquifer, effective cross-sectional flow area,
and the pressure gradient  that  induces the  water
to move. The groundwater  hydrologist should also
determine whether the aquifer is  in a discharge or
recharge area.  In a  discharge area,  water  leaves
the aquifer and emerges through  the  ground sur-
face as a spring. In recharge areas, water infiltrates
the ground and enters the aquifer. Lakes, streams,
and rivers may serve as recharge or discharge  areas,
or both, depending on the surrounding groundwater
level and geologic conditions.
Climatology

     Wind,  rain,  and temperature directly  affect
sanitary  landfill design and  operation. Windy sites
need to have litter fences at  the operating area and
personnel to clean up the area at the  end of the
day. Such  sites can  also be very dusty when the
soil dries,  and  this  may irritate  people  living  or
working nearby. Trees planted on  the perimeter of
a sanitary  landfill help keep dust and litter  within
the site.  Water sprinkling or the use of other dust
palliatives  are  often  necessary along  haul  roads
constructed of soil, crushed stone, or gravel.
     The effect  of rain that  infiltrates the  sanitary
landfill and influences solid  waste decomposition
has been discussed previously. Rain can also  cause
operational problems; many wet soils are difficult to
spread and  compact,  and traffic over  such soils is
impeded.
                                                                                                   11

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     Freezing  temperatures may  also  cause prob-     may be required, or it may be necessary to stockpile
lems. If the frost line is more than  6 in. below the     cover soil and protect it from freezing. A well-drained
ground  surface,  cover  material  may  be  difficult     soil is more easily worked in  freezing weather than
to obtain. A crawler dozer equipped with a ripper     one that is poorly drained.
                                            REFERENCE

               1.  REMSON, I., A. A. FUNGAROLI, and A. W. LAWRENCE.  Water  movement
                         in an unsaturated sanitary landfill. Journal of the Sanitary Engineer-
                         ing  Division,  Proc. ASCE, 94(SA2):307-317, Apr. 1968.
 12

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soils   and   geology
    A study of the soils and geologic conditions
of any area  in  which  a sanitary landfill  may  be
located is essential to  understanding how its con-
struction might  affect the environment. The study
should outline the  limitations that soils and geo-
logic  conditions impose  on  safe, efficient design
and operation.
    A comprehensive study identifies and describes
the soils present,  their variation, and their  dis-
tribution. It describes  the  physical  and chemical
properties of bedrock, particularly as it may relate
to the movement of water and gas (Figure 4). Per-
meability and workability are essential elements of
the soil evaluation, as are stratigraphy and structure
of the bedrock.
     Rock materials are generally classified as sedi-
mentary,  igneous,  or  metamorphic.  Sedimentary
rocks are formed from the products of erosion of
older rocks  and -from the deposits of  organic mat-
ter and chemical  precipitates. Igneous rocks derive
from the  molten  mass  in the depths of the earth.
Metamorphic rocks are derived  from both igneous
and sedimentary rocks that have  been altered chem-
ically or physically by  intense heat or  pressure.
     Sands, gravels, and clays are sedimentary in
origin.  The  sedimentary  rocks,   sometimes  called
                              Precipitation
                                                                  Surface runoff
                        ..... ...I...-.-.-. .,

                          t    t
                           Subsurface movement
                          KLIMESTONE soLUTipjTwiDENED JOINTS^
                              1      U—r—\
 ;.*"/•* •„** "•-*•  Permeable sandstone
   Figure 4.  Leachate and infiltration movements are affected by the characteristics of the soil and bedrock.
                                                                                           13

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aqueous rocks, are often very permeable and there-
fore  represent  a great  potential  for the flow  of
groundwater.  If  leachate develops  and  enters the
rock strata, contaminant travel will usually be great-
est in sedimentary formations. Other rocks common-
ly classed as sedimentary are limestone,  sandstone,
and conglomerates.  Fracturing and  jointing of sedi-
mentary formations  are common, and they increase
permeability.  In  fact, the  most productive  water-
bearing  strata for  wells  are formations of porous
sandstone,  highly  fractured limestone,  and  sand
and gravel  deposits. Siltstones  and  shales,  which
are also of sedimentary origin,  usually have  a very
low permeability  unless they have been subjected  to
jointing and form a series  of connected  open frac-
tures.
      Igneous and metamorphic rocks,  such as shist,
gneiss,  quartzite,  obsidian,  marble,  and granite,
generally have a very low permeability. If these rocks
are fractured  and jointed, however, they can serve
as aquifers of limited productivity.  Leachate  move-
ment through them  should not,  therefore, be cate-
gorically discounted.
      Information concerning the geology of  a pro-
posed site may be obtained from the U.S. Geologi-
cal Survey, the U.S. Army Corps  of Engineers, State
geological and soil agencies, university departments
of soil  sciences  and geology, and consulting soil
engineers  and geologists.
             Soil  Cover

                 The striking visual difference between a dump
             and a  sanitary landfill is the use of soil cover at the
             latter. Its compacted solid waste is fully enclosed
             within a  compacted earth layer at the end of each op-
             erating day, or more often if necessary.
                 The  cover  material  is  intended to  perform
             many functions at a sanitary landfill (Table 4); ideal-
             ly, the soil available at the site should  be capable
             of performing all of them.
                 The cover  material controls the  ingress and
             egress of flies, discourages the entrance of rodents
             seeking  food, and prevents scavenging birds from
             feeding on  the waste. Tests have  demonstrated that
             6 in. of compacted sandy loam will prevent fly emer-
             gence.1  Daily or  more frequent application of soil
             cover  greatly reduces the attraction of birds  to the
             waste  and also discourages rodents  from burrowing
             to get food. The cover material  is  essential  for
             maintaining a proper  appearance  of the  sanitary
             landfill.
                 Many soils,  when suitably compacted,  have a
             low  permeability, will not shrink, and can be used to
             control  moisture that  might otherwise  enter  the
             solid waste and produce leachale.
                 Control of gas  movement is also an  essential
             function of the cover material. Depending  on antic-
             ipated use of the completed  landfill  and the sur-
                                                TABLE4
                   Suitability  of  General Soil  Types as Cover  Material'
          Function
Minimize moisture entering
Minimize landfill gas venting
  through cover

Provide pleasing appearance
  and control blowing paper

Grow vegetation

Be permeable for venting
  decomposition gast
Clean    Clayey-silty    Clean    Clayey-silty
gravel      gravel      sand      sand
                                                                                  Silt
  P


  P


  E

  P
F-G

F-G


 E

 G
 P

 P


 E

P-F
G-E

G-E


 E

 E
G-E

G-E


 E

G-E
                                                                                             Clay
Prevent rodents from burrowing
or tunneling
Keep flies from emerging

G
P

F-G
F

G
P

P
G

P
G

P
Et
 Et


 Et


 E

F-G
    * E, excellent; G, good; F, fair; P, poor.
    t Except when cracks extend through the entire cover.
    i Only if well drained.
14

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rounding land, landfill gases can be  either blocked
by or vented through the cover material. A  perme-
able soil that does not retain much water can serve
as a good gas vent. Clean sand, well-graded gravel,
or crushed  stone are excellent when  kept  dry.  If
gases are to be prevented from venting through the
cover material,  a gas-impermeable  soil  with  high
moisture-holding  capacity  compacted  at  optimum
conditions should be  used.
     Enclosing the  solid waste within a compacted
earth shell offers  some protection against the spread
of fire.  Almost all  soils are noncombustible,  thus
the earth side walls and floor help  to confine a fire
within the cell. Top cover over a burning cell offers
less  protection because it becomes undermined and
caves in, thus exposing the overhead  cell to the fire.
The  use of a compactible soil of low  permeability  is
an   excellent   fire-control  measure,  because   it
minimizes the flow of oxygen into  the fill.
     To maintain a  clean  and  sightly  operation,
blowing litter must  be controlled. Almost  any work-
able soil satisfies this  requirement,  but fine sands
and  silts without  sufficient binder and moisture con-
tent  may create a dust problem.
     The soil  cover often serves as a road bed for
collection vehicles moving to and from the operating
area of the  fill. When it is,  it should be trafficable
under all weather conditions. In wet  weather,  most
clay  soils are  soft and  slippery.
     In general,  soil  used  to cover the  final lift
should  be capable of growing vegetation.  It should,
therefore, contain adequate nutrients  and  have  a
large moisture-storage  capacity.  A minimum  com-
pacted thickness  of 2 ft is recommended.
     Comparison of the soil characteristics  needed
to fulfill all  of these  functions indicates that some
anomalies exist.  To serve as a  road  base, the soil
should  be  well-drained  so that  loaded  collection
vehicles do not  bog  down. On  the  other hand,  it
should  have a low permeability if water is to  be
kept out of the fill, fire is to  be kept from spreading,
and  gas is not to be vented  through the final cover.
These differences can be solved  by  placing a  suit-
able  road  base on   top  of  the  normally  low
permeability-type cover material. A  reverse situation
occurs  when  landfill  gases are to be  vented  uni-
formly through the cover material. The soil  should
then be gas  permeable, have  a  small  moisture-
storage capacity,  and not be highly  compacted. As
before,  the criteria for moisture and  fire control re-
quire the soil  to  have a low permeability.  Leachate
collection and treatment facilities may  be required
if a  highly permeable soil is used  to vent gas uni-
formly through the cover materials;  if this is not
done, an alternative means  of venting  gas through
the cover material must be  sought.
     There are many soils capable of fulfilling the
functions  of cover material.  Minor differences in
soil grain  size or clay mineralogy can  make  signifi-
cant differences  in the  behavior of soils that fall
within  a given  soil group or  division.  In  addition,
different methods of  placing and compacting the
same soil can result  in a significantly different be-
havior.  Moisture  content  during  placement,  for ex-
ample,  is  a critical factor—it influences the soil's
density, strength, and porosity.
     The soils present at proposed sites should be
sampled by  augering,  coring, or excavating,  and
then be classified. The volume of suitable soil avail-
able for use as cover material can then be estimated
and the depth of excavation for waste disposal can
be determined.  Specific  information  on the top  5
ft of the soil mantle can often be obtained from the
Soil Conservation Service, U.S. Department of  Agri-
culture.
     Sanitary landfilling  is a carefully  engineered
process of solid waste disposal that involves appre-
ciable excavating, hauling, spreading, and  compact-
ing of  earth. When manipulating soils in this  man-
ner,  the Unified  Soil  Classification System (USCS)
is  useful.  Although recommendations for soil to be
used at a  landfill are often  expressed  in the U.S.
Department  of  Agriculture  textural  classification
system  (Figure 5), the USCS is preferred because it
relates  in more  detail the workability  of soils  from
an engineering viewpoint. (Table  5).
     Clay soils are very fine in texture even  though
they commonly contain small  to  moderate amounts
of silt and sand.  They vary greatly in their physical
properties,  which depend not  only  on  the small
particle size but on the  type of clay  minerals and
soil water  content. When dry, a clay soil can  be
almost  as  hard and  tough as  rock and  can  sup-
port heavy loads. When wet, it often becomes very
soft, is sticky or  slippery, and  is very  difficult to
handle. A clay soil swells when it becomes wet, and
its permeability  is very low.
     Many clay  soils  can absorb large  amounts of
water but, after  drying,  usually  shrink  and crack.
These  characteristics make many clays less desir-
able than other soils for use as a cover material.
The  large cracks that usually develop allow water
to enter the fill  and permit decomposition gases to
escape. Rats and insects can also enter or  leave
the fill through these apertures.
     Clay soil  can,  however, be used  for  special
purposes at a landfill. If it is desirable to  construct
an impermeable lining or cover to control leachate
and gas movement, many clays can be  densely  com-
pacted at optimum moisture. Once they are in place,
it  is almost always necessary to keep them moist
so they do not crack.
                                                                                                    15

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     The  suitability  of  coarse  grained   material
(gravel  and sand) for cover material depends most-
ly on grain size distribution  (gradation), the shape
of grains,  and  the amount  of  clay  and silt  fines
present. If gravel, for example, is poorly graded and
relatively free of  fines,  it  is not  suitable  as cover
material for moisture, gas, or fly  control. It cannot
be compacted enough, and  the  gravel  layer will be
porous and highly permeable; this would allow water
to enter the fill easily.  Flies would  have little diffi-
culty emerging through the loose particles. On  the
other hand, a gravel layer no  more  than 6 in. deep
would  probably discourage  rats  and other  rodents
from burrowing into the fill and would provide good
litter control.  If gravel is fairly  well-graded and con-
tains 10 to 15 percent sand and  5 percent or more
                                                                   50 \?
                     100    90    80    70    60    50    40     30     20     10
                                       Sand —2 0 to 0 05 mm diameter
                                       Silt —0 05 to 0 002 mm diameter
                                       Clay — smaller than 0 002 mm diameter
                           COMPARISON OF  PARTICLE  SIZE  SCALES

 Sieve openings in  inches                     U.S. Standard Sieve Numbers
         3   2 l'/2  1  3/4  '/z  3/e    4      10     20   40  60        200
n
USDA

uses
1 1 1 1 1 1

GRAVEL
II 1 1 1 1
1 1 1
SAND
Very 1
coarse Coarse] Med

GRAVEL
Coarse | Fine
Fine


„._ „ SILT
"Very ilu
fine
CLAY

SAND
Coarse
Medium 1
Illll i i I i IIMII 111 i II
Fine


SILT OR CLAY
II III
|
      100   50            105      2     1     f 0.42 0.25   0.1 /  0.05    0.02  0.01  0.005  0.0002 0.001
                                                0.5             0.074
                                         Grain size in Millimeters

 Figure 5. Textural classification chart (U.S. Department of Agriculture)  and comparison of particle size scales.
16

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.0, .0
                       o o o
                        o o
                       O 0 0
                                                                                             17

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fines, it  can make an excellent cover. When com-
pacted, the  coarse particles maintain grain-to-grain
contact, because they are held in place by the bind-
ing action of  the  sand and fines and cohesion  of
the clays. The presence of fines greatly decreases
a soil's permeability. A  well-graded,  sandy, clayey
gravel  does not develop shrinkage  cracks.  It can
control flies and rodents, provide odor control, can
be  worked  in  any weather, and  supply excellent
traction for  collection trucks and other vehicles.
     Many soils classified as sand  (grain size gen-
erally in the range of 4.0 to 0.05 mm)  contain small
amounts of  silt and clay and often some gravel-size
material  as  well.  A well-graded  sand that  contains
less than 3  percent fines usually has good compac-
tion characteristics.  A small increase  in fines, par-
ticularly  silt,  usually improves  density and allows
even  better compaction. A poorly  graded  sand is
difficult  to  compact unless it  contains  abundant
fines. The permeability  of clean sand soils  is  al-
ways high, even when compacted, and they  are not,
therefore, suitable for controlling the  infiltration of
water. They are also ineffective in constraining flies
and gases.
     A well-drained sandy soil can be  easily worked
even  if  temperatures  fall below freezing,  while a
soil with a  large  moisture-storage  capacity  will
freeze.
      Practically the only soils  that can be ruled
out for use as cover material  are  peat and  highly
organic soils.  Peat is an earthy soil (usually  brown
to  black) and  is  composed largely  of partially de-
composed plant matter. It usually  contains a high
amount of voids,  and  its water content may range
from 100  to  400 percent of  the  weight of dried
solids.  Peat  is  virtually  impossible to compact,
whether wet  or  dry.  Peat deposits  are scattered
throughout  the country but are most abundant in
the States  bordering  the Great Lakes. Highly  or-
ganic soils  include sands, silts, and clays that con-
tain at least  20  percent organic matter. They  are
usually very dark, have an earthy odor when freshly
turned,  and often contain fragments  of decompos-
 ing vegetable  matter. They are very difficult to com-
pact, are normally  very sticky, and  can vary  ex-
tremely  in their moisture content.
      Many  soils  contain  stones and boulders of
varying  sizes, especially those in  glaciated  areas.
The use of  soils  with boulders that hinder  compac-
tion should be avoided.
      Soil surveys prepared by the Soil Conservation
 Service  of the U.S. Department of Agriculture  are
 available for  a major  portion of the country.  Local
assistance  in using and interpreting  them  is avail-
able through  soil conservation districts  located in
some  3,000  county seats throughout  the United
States. The surveys cover such specific factors as
natural drainage, hazard  of  flooding,  permeability,
slope,  workability,  depth  to  rock,  and stoniness.
They are  commonly used  to locate potential areas
for sanitary  landfills.  They also can  serve  as the
basis  for  designing  effective  water  management
systems and selecting suitable  plant cover to con-
trol runoff and erosion during and  after completion
of fill operations. Sanitary landfill owners and their
consultants can avoid costly investigations of un-
suitable sites by using soil surveys to select areas
for which detailed  investigations appear warranted.
Using soil surveys  for the foregoing purposes does
not, however, eliminate the need for making detailed
site investigations.
Land Forms

     A sanitary landfill can  be constructed on vir-
tually any terrain, but some land forms require that
extensive site improvements  be made and expensive
operational  techniques followed. Flat or gently roll-
ing  land  not  subject  to flooding is best,  but this
type is also highly desirable  for farming and indus-
trial parks,  and this drives up the purchase price.
     Depressions, such as canyons and ravines, are
more efficient than flat areas from a land  use stand-
point  since  they can  hold  more solid  waste per
acre. Cover material may, however, have to be hauled
in from surrounding areas. Depressions  usually re-
sult when  surface  waters run off and  erode the
soil and rock.  By their nature, they require special
measures to  keep surface waters from  inundating
the  fill.  Permeable  formations that  intersect the
side walls or floor  of the fill  may  also have  to be
lined with an impervious layer of clay or other ma-
terial to control the movement of  fluids.
     There  are  also  numerous man-made  topo-
graphic features  scattered over the country—strip
mines, worked-out  stone  and  clay quarries, open
pit  mines, and sand and gravel pits. In most cases,
these  abandoned depressions are useless, dangerous
eyesores. Many  of  them  could be  safely  and eco-
nomically  reclaimed by utilizing them as  sanitary
 landfills. Clay  pits, for example, are located in most
 impermeable formations, which are natural barriers
to gas and  water movement. Abandoned strip mines
also are naturally suited  for use as sanitary land-
fills. Most  coal  formations are underlaid  by  clays,
shales, and siltstones that have  a very low perme-
 ability. When permeable formations, such  as sand-
 stones, are encountered near an  excavation, imper-
 meable soil layers can be constructed from  the near-
 by abundant spoil. Abandoned limestone,  sandstone,
 siltstone, granite,  and traprock quarries and open
 18

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pit mines generally require more extensive improve-
ments because they are in permeable or often open-
fractured formations. The pollution potential of sand
and  gravel pits is  great, and worked-out pits con-
sequently require extensive investigation and proba-
bly  expensive improvements to control  gas  move-
ment and water pollution.
     Marsh and tidal lands may also be filled,  but
they are less desirable from an ecological point of
view.  They  have  little value as  real  estate,  but
possess considerable ecological value as nesting and
feeding grounds for wildlife.  Filling of such  areas
requires,  however,  the permanent lowering of the
groundwater or the raising of the ground surface to
keep  organic  and soluble solid waste from  being
deposited in  standing water. Roads for collection
vehicles  are also needed,  and cover material gen-
erally has to be hauled in.
                                             REFERENCE

                1. BLACK, R. J., and A. M. BARNES.   Effect of earth cover on fly emergence
                          from sanitary landfills. Public Works, 89(2):91-94, Feb.  1958. Con-
                          densed  and  reprinted as Fly emergence control in sanitary landfills.
                          Refuse  Removal Journal,  1(5):13, 25, May 1958.
                                                                                                   19

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sanitary   landfill   design
     The designing of a  sanitary landfill calls for
developing a  detailed description  and plans that
outline the steps to be  taken to  provide for the
safe, efficient disposal of the quantities and types
of solid wastes  that are  expected to be received.
The  designer outlines  volume requirements,  site
improvements (clearing of the land, construction of
roadways and buildings, fencing,  utilities), and all
the equipment necessary  for day-to-day operations
of the specific landfilling  method involved. He also
provides  for  controlling  water pollution and  the
movement of decomposition gas. The sanitary land-
fill designer should also recommend  a specific use
of the site after  landfilling is completed. Finally, he
should determine capital  costs and  projected op-
erating expenditures for  the estimated  life of the
project.

Volume Requirements

     If the rate  at which  solid wastes are collected
and the capacity of the proposed site  are known, its
useful  life  can  be estimated. The  ratio of  solid
waste to cover material volume usually  ranges be-
tween 4:1 and 3:1; it is, however,  influenced by the
thickness of the cover used and cell  configuration.
If cover material is not excavated from the fill site,
this  ratio may  be  compared with the  volume of
compacted  soil  waste and  the capacity  of  a  site
determined (Figure 6). For example,  a town having
a 10,000 population and a per capita  collection rate
of 5  Ib per day must dispose of, in a year, 11 acre-ft
of solid waste if it is compacted to 1,000 Ib per cu
yd. If it were compacted  to only 600 Ib per cu yd,
the volume disposed of in a year would  occupy 19
acre-ft. The volume of soil required for the 1,000-lb
density at a solid waste-to-cover ratio of 4:1  would
be 2.75 acre-ft;  the  600-lb density waste  would
need 4.75 acre-ft. A density of 800 Ib per cu yd is
easily achievable if the compacting of a representa-
tive municipal waste is involved. A density of 1,000
Ib per cu yd can usually be obtained if the waste
is spread and compacted according to procedures
described in  Chapter 6.
     The number of tons to be disposed of at a pro-
posed sanitary landfill can be estimated from data

            24      6      ,8      10
        SOLID WASTE COLLECTED (Ib/capita/talendor dayl

    Figure  6.  Determining the yearly volume  of
compacted solid waste generated by a community of
10,000 people.
20

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    2000 -
                                                        800 •
              200     400     600     800     1000
              SOLID WASTE DISPOSED OF DAILY (Ions)

     Figure 7.   Determining the daily volume of com-
pacted solid waste generated by large communities.

recorded when solid wastes are delivered to disposal
sites. The  daily volume  of  compacted solid waste
can then be easily determined for a large community
(Figure 7) or for a small  community (Figure 8). The
volume of soil required to cover each day's waste is
then estimated by using the appropriate solid waste-
to-cover ratio.
     The terms used to report  densities at landfills
can be confusing. Solid waste density (field density)
is the weight of a unit  volume  of solid waste  in
place. Landfill density is the weight  of a unit volume
of in-place  solid waste  divided by the  volume of
solid  waste and its cover material. Both methods of
reporting density are usually expressed  as pounds
per cubic yard, on an in-place weight basis, includ-
ing moisture, at time of the test,  unless otherwise
stated.

Site Impovements

     The plan for a sanitary landfill should prescribe
how the site will be improved  to provide an orderly
and sanitary operation. This may simply involve the
clearing of shrubs,  trees, and  other obstacles  that
could  hinder vehicle  travel and  landfilling  opera-
tions  or it could  involve the construction of build-
ings,  roads, and  utilities.
     CLEARING  AND  GRUBBING.  Trees  and brush
that hinder landfill equipment or collection vehicles
must  be removed. Trees that cannot be pushed  over
should  be  cut as close as possible to the ground
so that the stumps do  not  hinder compaction or
obstruct vehicles.  Brush and tall grass in working
areas can  be  rolled  over or  grubbed.  A large  site
should  be  cleared in increments to avoid  erosion
                                                      < 400 •
                                                      a.
                                                      Ł
                                                      O
              40      80      120     160     200
               SOLID WASTE DISPOSED OF DAILY (tons)
    Figure 8.   Determining the daily volume of com-
pacted solid waste generated  by small  communities.
and scarring of the land. If possible, natural wind-
breaks and green belts of trees or brush should be
left in strategic  areas to improve appearance  and
operation.  Measures  for minimizing  erosion  and
sedimentation problems are outlined in the publica-
tion Community  Action Guidebook for Soil Erosion
and Sediment Control.'
     ROADS. Permanent roads should be provided
from the public road system to the site. A large site
may have to have permanent roads  that lead from
its  entrance to  the vicinity of  the working area.
They should be designed to support  the anticipated
volume  of truck  traffic.  In general, the  roadway
should consist of two lanes  (total minimum  width,
24  ft),  for two-way traffic. Grades  should not  ex-
ceed  equipment  limitations.  For  loaded vehicles,
most  uphill grades should be less than 7 percent
and downhill grades less than 10.  Road alignments
and pavement designs  have been  adequately  dis-
cussed  elsewhere.2'3 The initial  cost of  permanent
roads is higher than  that  of temporary  roads, but
the savings in equipment  repair and  maintenance
could  justify the  building of permanent,  on-site
roads.
     Temporary roads are  normally  used to deliver
wastes to the working face from the permanent road
system, because the location of the working face is
constantly changing. Temporary  roads may be con-
structed  by compacting the natural soil present and
by controlling drainage  or by topping them with a
layer of a tractive material, such as gravel, crushed
stone, cinders, broken concrete, mortar, or bricks.
Lime,  cement, or asphalt binders may make such
roads more  serviceable.
     If fewer than  25 round trips per day to the
                                                                                                  21

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landfill are expected, a graded and compacted soil
will usually suffice.  More than 50 round trips per
day generally justifies the use of calcium chloride  as
a dust  inhibitor  or  such binder  materials as soil
cement or asphalt. A base course plus a binder is
desirable if more than 100 to  150 round trips per day
are anticipated.
     SCALES. Recording the weights  of solid waste
delivered  to  a site  can help regulate  and control
the sanitary  landfill operation as  well as the solid
waste collection system that serves it.
     The  scale type and  size used will depend  on
the scope of the operation. Portable  scales  may
suffice for a small site, while an  elaborate system
employing load cells, electronic relays, and printed
output may be needed at a large sanitary landfill.
Highly automated electronic scales  and recorders
cost more than a portable, simple, beam scale,  but
their use  may often be justified,  because they are
faster  and  more  accurate.  The  platform or scale
deck may be constructed of wood,  steel, or concrete.
The first  type is the least expensive, but also  the
least durable.
     The  scale should be able to  weigh the largest
vehicle that will use the landfill on a routine basis;
30 tons is usually adequate.  Generally, the platform
should  be long enough to weigh  all  axles  simulta-
neously. Separate axle-loading scales (portable ver-
sions) are the cheapest,  but they are less accurate
and slower operating.  The scale platform should  be
10 by 34 ft  to  weigh most collection  vehicles. A
50-ft  platform will accommodate  most trucks with
trailers.
     The  accuracy and  internal  mechanism of the
scale  and the  recording device  should meet  the
commercial requirements imposed by the State and
any other jurisdiction involved, particularly if user
fees are based  on weight.  Recommended scale  re-
quirements  have been  outlined  by  the  National
 Bureau of Standards.4
     Since weights are seldom recorded closer than
to the nearest tenth of a ton and most applied loads
are between  8 and  14 tons,  a  scale accuracy of
 ±1.0  percent is  acceptable. All  scales  should  be
periodically  checked and certified as to standard
accuracy.
      Both mechanical and  electronic scales should
 be tested  quarterly  under load.  The  inspection
should include: (1) checking for a change in indi-
cated  weight as a  heavy load  is moved from  the
front to  the  back of the scale;  (2) observing  the
 action of the  dial during weighing for an  irregularity
 or "catch" in its motion; (3) using test weights.
      BUILDINGS. A building  is  needed for office
space and employee facilities at all but the smallest
 landfill; it can also  serve as a scale  house. Since a
landfill operates in wet and cold weather, some pro-
tection from the elements should be provided. Opera-
tional  records  may  also  be kept  at  a large site.
Sanitary facilities should be provided for both land-
fill and collection personnel. A building should also
be provided for equipment storage and maintenance.
     Buildings  on sites that will be used  for less
than 10 years should be temporary types and, pref-
erably, be movable.  The design  and location of all
structures should  consider  gas movement  and  dif-
ferential  settlement  caused  by the  decomposing
solid  waste.
     UTILITIES. All sanitary landfill sites should have
electrical, water, and sanitary services. Remote sites
may have to extend existing services or use accept-
able substitutes. Portable chemical  toilets  can  be
used to avoid the high cost of extending sewer lines,
potable water  may be  trucked in,  and an  electric
generator  may  be used  instead of having power
lines  run into the site.
     Water should be  available  for  drinking,  fire
fighting,  dust control, and employee sanitation. A
sewer line  may be  called  for,  especially  at large
sites  and at those where leachate is collected  and
treated  with  domestic  wastewater. Telephone or
radio communications are also desirable.
      FENCING. Peripheral and litter fences  are com-
monly needed at sanitary landfills. The first type is
used  to control or limit access, keep  out  children,
dogs,  and other large animals,  screen the  landfill,
and delineate  the  property line. If  vandalism  and
trespassing are to be discouraged, a 6-ft high fence
topped with three strands of barbed wire projecting
at  a  45° angle is  desirable. A wooden  fence or  a
hedge may  be  used to screen the  operation from
view.
      Litter fences are used to  control blowing paper
in the immediate vicinity of the working face. As  a
general  rule, trench operations  require less litter
fencing  because the solid  waste tends to  be  con-
fined within the walls of the trench. At a very windy
trench site, a  4-ft snow  fence will usually suffice.
 Blowing  paper is  more  of a problem in  an  area
operation; 6- to 10-ft litter fences  are often needed.
Some litter fences  have been  specially  designed
 and fabricated  (Figure 9).  Since the location of the
working face shifts frequently,  litter fences should
 be movable.


Control of Surface Water

      Surface water courses should be diverted from
 the sanitary landfill. Pipes may be  used in gullies,
 ravines, and canyons that are being filled  to trans-
 mit  upland drainage through  the  site and open
 channels employed  to divert runoff from surround-
 22

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     Figure 9.   Specially designed and fabricated litter-control fences are often used near the working face of
sanitary landfill.
ing areas (Figure 10).  Sump pumps  may  also  be
used.  Because of operating  and maintenance  re-
quirements, the  use of  mechanical equiment for
water  control  is,  however,  strongly  discouraged
unless the  control is needed only  temporarily.  If
trenches or depressions are being filled, collection
sumps and pumps may be used to keep them  from
flooding.  Equipment  sizes  can  be  determined  by
analyzing storm  and  flood  records  covering about
a 50-year period. Counseling and guidance in  plan-
ning  water management  measures are  available
through  local soil  conservation  districts upon re-
quest. A landfill located in a flood plain should be
protected by impervious dikes and  liners. The top
of the dike should be wide enough for maintenance
work  to  be carried  out and may be  designed for
use by collection and landfill vehicles.
     The top cover material of a landfill should be
graded to allow runoff of rainfall. The grade of the
cover will depend on the material's  ability to  resist
erosion and the planned use of the  completed site.
Portable or permanent drainage channels  may be
         Upland drainage flow
                                                                    SECTION
     Figure 10.  Plan and section views of the use of a diversion ditch to transmit upland drainage around a
sanitary landfill.
                                                                                                    23

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constructed to intercept and  remove runoff water.
Low-cost,  portable drainage channels can be made
by bolting together half-sections of corrugated steel
pipes.  Surface water that runs off stockpiled cover
material may  contain suspended solids and should
not be allowed to enter watercourses unless it has
been ponded to remove settleable solids.

Groundwater Protection

     It is a basic premise that groundwater  and the
deposited  solid  waste not be allowed  to  interact.
It is unwise to assume that a leachate will be diluted
in  groundwater because very little mixing occurs  in
an aquifer since the groundwater flow there is usual-
ly laminar.
     When issuing permits  or  certificates, many
States  require that groundwater and  deposited solid
wastes be 2 to 30 ft apart. Generally, a 5-ft separa-
tion will remove enough readily decomposed organics
and coliform bacteria to make  the liquid bacteriolog-
ically safe.5' *  On the other hand, mineral pollutants
can travel long distances through soil or rock forma-
tions.  In addition to other considerations, the sani-
tary landfill designer must evaluate the: (1)  current
and projected  use of the water resources of the area;
(2) effect  of  leachate on  groundwater quality; (3)
direction of groundwater movement; (4) interrela-
tionship of this aquifer with other aquifers and sur-
face waters.
     Groundwater mounds, rises in the piezometric
level of an aquifer in a  recharge area,  have been
found  at several landfills.7 The mounds are reported
to be up to 5  ft above the surrounding groundwater
level,  and they  have intersected  deposited  solid
waste.  The investigators  believe the water  table
probably rose because: (1) the permeability of the
landfill's  soil  boundary  decreased  as  a result  of
excavation and reworking; (2)  more water infiltrated
through  the  cover material  and solid waste than
through  the  undisturbed soils  of the surrounding
area.7
     If a groundwater  mound intersects the solid
waste, leachate will undoubtedly enter the  ground-
water  and  may emerge as a spring around the toe
of  the fill where the groundwater table intersects
the ground surface. Both surface and groundwaters
may, therefore, be endangered if a mound forms.
     An impermeable liner may be employed to con-
trol the movement  of fluids. One of the most com-
monly used  is a well-compacted natural clay  soil,
usually constructed as a  membrane 1 to 3  ft thick.
It  must, however, be kept moist. If sufficient clay
soil is not available locally,  natural clay additives,
such as montmorillonite,  may be disked into  it  to
form an effective liner. The use of additives  requires
evaluation   to   determine  optimum   types  and
amounts.
     Since  synthetic  liners  have  been  used  to
construct  wastewater-holding-and-treatment  ponds,
they may have an application in solid waste disposal
operations. They are usually made of butyl rubber,
polyethylene, or polyvinyl  chloride and are installed
in  multiple  layers.  (If the  movement of both gas
and  leachate is to be  controlled, polyvinyl chloride
should work  better than polyethylene because it is
less permeable by  gas.)  The  membranes  must  be
put down carefully to avoid punctures, and  layers of
soil (usually sand) must be placed on both sides of
them. Asphalt  liners, which have been used to re-
duce  seepage  from  canals and  ditches,  may also
have an application in  a solid  waste disposal opera-
tion.
     The use of an impermeable barrier requires that
some method be provided for removal of  the con-
tained fluid. If a natural ravine or  canyon is  involved,
the removal  point should be  the downstream end
of the filled  area. The fluid in a bowl-shaped  liner
could be  pumped by  a well  or  series of wells  or
it  could exit through gravity  outlets  in the  bottom
of the liner. In the  latter  case, the pipes should  be
sloped l/z  to l/4 in. per  ft.
     It is often possible  to permanently or  tempo-
rarily lower the groundwater in free-draining,  gravel-
ly, and sandy soils.  Drains, canals, and ditches are
frequently  used to intercept  the groundwater and
channel it  to surface  water or recharge area at a
lower elevation. Doing this generally requires that
the designer have a  thorough  knowledge of the soil
permeabilities  and the groundwater  flow system in
the area. It is inadvisable to use temporary methods,
such as  wells, to  lower the water table because it
will rise after pumping ceases, and the waste will be
inundated. It is well  to recognize  that highly  perme-
able soils that  can be  readily drained by ditching or
pumping will offer  equally little resistance  to the
movement  of leachate from the  decomposing solid
waste. Even  though groundwater can be kept from
coming into  direct  contact with the  solid waste, in
most climates infiltrated surface  water will probably
enter the  solid waste  eventually, cause  leaching,
and then percolate  through the  underlying  porous
soil  to enter the lowered groundwater. It  is advis-
able, therefore, to  view  sites in  highly permeable
material  with extreme caution.
     Little work  has  been  done to determine the
types and  costs of leachate treatment. Analysis of
leachate samples  from a few landfills and  labora-
tory lysimeters indicates that  leachate is a complex
liquid waste and  has variable  characteristics. Since
most of the contaminants  in leachate are water solu-
ble, conventional biological and chemical treatment
 24

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methods are probably required and, hopefully, will
prove effective.
     To  help  establish if  a landfill  is  creating a
groundwater  and surface water pollution problem,
a series of observation wells and sampling stations
can be used to periodically monitor the water quality.
Data on the upstream or uncontaminated water and
downstream water quality are necessary to evaluate
the pollution potential.

Gas Movement Control

     An important part of sanitary landfill design is
controlling the movement  of decomposition gases,
mainly carbon dioxide and  methane.  Traces of  hy-
drogen sulfide and other odorous gases may also be
involved.
     Methane (CH4)  is a colorless,  odorless gas that
is highly explosive in concentrations of 5 to 15 per-
cent when in the presence of oxygen. In a few in-
stances, methane gas  has moved from a  landfill
and  accumulated in  explosive  concentrations  in
sewer lines and  nearby buildings. Gas from  landfills
has  also  killed  nearby vegetation, presumably by
                                    Slope
                                    . Slope
               Final cover material
                 Vented gas
          Cell
                                        f I
     Figure 11.  Gravel vents or gravel-filled trenches
 can  be used to control  lateral gas  movement in  a
 sanitary landfill.
excluding oxygen from the root zone. Carbon dioxide
(C02) is  also a colorless, odorless gas, but it does
not support  combustion.  It is approximately  1.5
times as heavy as air and is soluble in water. The
C02 reacts to a limited extent to form carbonic acid
(H2C03),  which can dissolve mineral matter, partic-
ularly carbonates,  in refuse, soil, and rock. If this
occurs, the mineral content or hardness of the water
increases, as has  been  noted  at wells located  near
landfills  and dumps.
     In general, no problems arise when landfill gas
can disperse into  the atmosphere.  If the  fill has a
relatively impermeable cover, however, the methane
will try  to vent into the atmosphere by moving
laterally  through a more permeable  material.
     The natural soil, hydrologic, and geologic condi-
tions  of  the site may provide  control of gas move-
ment.  If not,  methods  based on  controlling gas
permeability can be constructed. The  following  have
been  used or are considered possible.
     PERMEABLE  METHODS. Lateral  gas movement
can  be  prevented by  using a  material that  is—
under alf circumstances—more permeable than the
surrounding soil; gravel vents or gravel-filled trench-
es have  been employed  (Figure 11). Preferably, the
trenches should be somewhat  deeper than the fill
to make  sure they intercept all  lateral gas flow. The
filter  material  should be  graded to avoid infiltration
and clogging by adjacent  soil  carried in  by water.
If possible,  the trench  should be  built so that it
drains naturally; field tile  is  often  placed in  the
bottom of the trench. The surface of gravel trenches
should be kept free of soil and vegetation, because
they retain moisture and  hinder venting.
      In  another method,  vent  pipes are inserted
through  a relatively impermeable top cover (Figure
12).  Collecting laterals   placed  in  shallow  gravel
trenches within or on top of the waste can be con-
nected to the  vertical riser. The sizes and  spacings
required have not been established,  but they depend
on the rate of  gas production,  total weight of  solid
waste, and the gas permeability of both  the  cover
and  the surrounding soil. In  some cases, vertical
risers have been  used to burn  off  the  gas.  Pipe
vents should  not  be located near buildings, but if
this  is  unavoidable, they should discharge above
the roof line.
      Pumped  exhaust wells may be used for  gas
venting.  In this method,  pipe vents are attached to
the line of a  suction pump  to  create differential
driving pressure for gas movement. This method is
costly and  requires frequent maintenance.
      IMPERMEABLE METHODS.  The movement of
gas through soils can be controlled by using materials
that are more impermeable to it than the  surround-
ing soil. An  impermeable barrier  can be used to
                                                                                                   25
      470-406 O - 72 - 5

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               V

          Vegetation
                       \f
                ented gas I i
        Final cover material
         Gravel
                              Perforated lateral
     Figure 12.   Gases are sometimes vented out of
a sanitary landfill via pipes that are inserted through
a relatively impermeable top cover and are connected
to collecting laterals placed in shallow gravel trenches
within or on top  of the  waste.
contain the gas and  vent  it through the top cover
or simply to block the flow of gas.
     The  most common method, and possibly the
most practical, calls for the use  of compacted clay.
The  material must, however,  be kept moist,  other-
wise it could shrink and crack. (Other fine grained
soils may also be used, with  the same stipulation.)
The clay can be placed as a liner in an excavation
or installed  as  a curtain wall to block underground
gas flow  (Figure  13).  A clay layer 18  to  48  in.
thick  is probably  adequate,  but it  should  be con-
tinuous and  not be penetrated by solid waste or out-
croppings of the surrounding soil or rocks. The liner
should be constructed as the fill progresses, because
prolonged exposure to air will dry the clay and cause
it to shrink  and crack.
     The use of synthetic membranes was described
in the section on Groundwater Protection.

Sanitary Landfilling Methods

     The designer of a sanitary landfill should pre-
scribe the  method of construction  and the  proce-
dures to be  followed in  disposing of the solid  waste,
because there is no "best method" for all sites. The
method selected depends on the physical conditions
involved and the  amount and types of solid waste
to be handled.
     The  two basic landfilling methods are  trench
and area; other approaches are only modifications. In
general, the trench method is used when the ground-
water  is low and  the  soil  is  more  than  6 ft deep.
It is best employed on flat or gently rolling land.
The  area  method  can  be  followed  on most  topog-
raphies and is  often used if large quantities of solid
                                        *    final ....*... 9r'
       ade
4
7
                                                                                   Clay barrier
                                         Proposed    ^    final     4    grade

                                         	I	

                                     '   Vented gas  I
                                                                                        Clay barrier
     Figure 13.  Clay can be placed as a liner in an excavation or installed as a curtain wall to block underground
 gas flow.
 26

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                    i^^V. Cell :.-:  :*%Ł Daily
  ^SJ^^
                           Original  ground
     Figure 14.  The cell is the common building block in sanitary landfilling. Solid waste is spread and compacted
in layers within a confined area. At the end of each working day, or more frequently, it is covered completely with
a thin, continuous layer of soil, which is then also compacted. The compacted waste and soil constitute a cell. A
series of adjoining cells makes up a lift. The completed fill consists of one or more lifts.
waste must be disposed of. At many sites, a com-
bination of the two methods is used.
     CELL CONSTRUCTION AND COVER MATERIAL.
The building block common  to both methods is the
cell. All the solid waste  received is spread and com-
pacted in layers within a confined area. At the end of
each working day, or more frequently, it is covered
completely with a thin, continuous layer of soil, which
is  then also compacted. The compacted waste and
soil cover  constitute a  cell. A  series of adjoining
cells,  all of the same height, makes up a lift (Figure
14). The completed fill consists of one or more  lifts.
     The dimensions of the cell are determined  by
the volume of the compacted waste, and this,  in
turn,  depends  on  the density of the in-place solid
waste. The  field  density of most compacted solid
waste within the cell should be at least 800 Ib per
cu yd. (It  should be considerably higher if large
amounts of  demolition rubble, glass,  and well-
compacted   inorganic materials are  present.)  The
800-lb figure may be difficult to achieve if brushes
from  bushes and  trees, plastic turnings, synthetic
fibers, or rubber  powder and trimmings  predomi-
nate.  Because  these materials normally tend to re-
bound when  the compacting load is  released,  they
should be  spread in layers up  to 2  ft thick,  then
covered with 6 in. of soil.  Over this, mixed solid
waste should be spread and compacted.  The over-
lying  weight keeps  the fluffy or  elastic  materials
reasonably compressed.
     An orderly operation should  be achieved  by
maintaining a narrow working face (that portion of
the uncompleted  cell on which  additional  waste is
spread and  compacted). It should be wide enough
to prevent a backlog of  trucks waiting to dump, but
not be so  wide  that  it becomes  impractical  to
manage properly—never over 150 ft.
     No hard-and-fast rule can be laid down regard-
ing the proper height of a cell. Some designers think
it should be 8 ft or less, presumably because this
height will  not cause severe settlement problems.
On the other hand,  if a multiple lift operation is in-
volved and all the cellls are built to the same height,
whether 8 or 16 ft, total settlement should not dif-
fer  significantly.  If land and  cover material are
readily available, an 8-ft  height restriction might be
appropriate, but heights up  to 30 ft are  common
in  large operations. Rather than deciding on  an ar-
bitrary figure, the designer should attempt to keep
cover material volume at  a  minumum  while ade-
quately disposing of as much waste as possible.
     Cover material volume  requirements are de-
pendent on the surface area of waste to  be covered
and the thickness of soil needed to perform  partic-
ular functions. As  might be expected, cell  configu-
ration  can  greatly affect the volume of cover ma-
terial  needed. The surface area to be covered should,
therefore, be kept minimal.
     In general, the cell  should  be about square,
and its sides should be sloped as steeply as  practi-
cal operation will permit. Side slopes of  20°  to 30°
will not only keep  the surface area,  and hence the
cover material volume, at a minimum but  will also
aid in shredding and obtaining good compaction of
solid  waste,  particularly  if it  is spread in  layers
not greater than 2 ft thick and worked from the bot-
tom of the slope to the top.
     TRENCH METHOD.  Waste is spread and com-
pacted  in  an  excavated trench.  Cover material,
which is taken from the  spoil of the  excavation,  is
spread and  compacted over the waste to form the
basic cell structure (Figure  15).  In this  method,
cover material is  readily available as  a result of
the excavation. Spoil  material not needed  for daily
                                                                                                   27

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     DAILY EARTH COVER (6 IN ) - _-^
     1—ORIGINAL
       GROUND
     Figure 15   In the trench method of sanitary landfilling, the collection truck deposits its load into a trench
where a bulldozer spreads and compacts it. At the end of  the day, the trench  is extended, and the excavated
soil is used as daily cover material.
cover may be stockpiled  and later used as a  cover
for an area fill operation on top of the completed
trench fill.
     Cohesive soils, such  as glacial till  or  clayey
silt, are desirable for use in  a trench operation be-
cause  the walls between the trenches can be thin
and nearly vertical. The trenches can, therefore,  be
spaced very closely. Weather and the length of time
the trench is  to remain open also affect soil stabil-
 ity and  must be considered  when the slope of the
trench walls  is being designed.  If the trenches are
 aligned  perpendicularly to the prevailing  wind, this
can  greatly reduce  the amount  of  blowing litter.
The  bottom of the trench should  be  slightly sloped
for drainage,  and  provision  should  be made  for
surface water  to run off at the low end of the trench.
Excavated  soil can  be used  to form a temporary
berm on the  sides of the trench to divert  surface
water.
     The trench can be as deep as soil and ground-
water  conditions safely allow, and  it should be at
least twice as wide an any compacting equipment
that will work in it.  The equipment at the site may
excavate the  trench continuously at  a  rate geared
      Figure 16.  In the area method of sanitary landfilling, a bulldozer spreads and compacts th
-------
to landfilling requirements.  At  small  sites, excava-
tion may be done on a contract basis.
     AREA METHOD. In this method, the waste  is
spread  and compacted on  the  natural  surface  of
the ground, and cover material is spread and com-
pacted over it (Figure 16). The area method is used
on flat or gently sloping land and  also in quarries,
strip mines, ravines, valleys, or other land depres-
sions.
     COMBINATION  METHODS. A  sanitary  landfill
does not need to be operated by using only the area
or trench method. Combinations of the two are possi-
ble, and flexibility is, therefore, one of sanitary land-
filling's greatest assets. The methods used  can be
varied  according to the constraints of a particular
site.
     One common variation  is the progressive slope
or ramp  method, in which the solid waste is spread
and  compacted  on a slope.  Cover material  is ob-
tained  directly in front of  the working  face  and
compacted on the waste (Figure 17). In this way,
a small excavation is made for a portion of the next
day's waste. This technique allows for  more effi-
cient use of  the disposal site when a single lift  is
constructed than  the  area  method  does,  because
cover does not have to be imported,  and a  portion
of the waste is deposited below the original surface.
     Both  methods might have to be used  at the
same site  if  an extremely  large  amount  of solid
waste must be disposed of. For example, at a site
with a thick soil zone over much of it but with only
a  shallow  soil over  the  remainder,  the designer
would  use  the  trench  method in the  thick  soil
zone and  use the extra spoil  material obtained to
carry out the  area  method  over  the rest of the
site. When  a site  has  been  developed  by either
method,  additional  lifts can  be constructed using
the area method by having cover material hauled in.
     The  final surface  of the completed  landfill
should be so designed that ponding of precipitation
does not occur. Settlement must, therefore,  be con-
sidered. Grading of the  final surface should induce
drainage  but not be so  extreme  that  the cover
material  is  eroded.  Side  slopes of the  completed
surface should  be  3 to  1 or flatter to minimize
maintenance.
     Finally,  the designer should consider complet-
ing the sanitary landfill in  phases so that portions of
it  can  be  used as  parks and  playgrounds, while
other parts are still accepting solid wastes.

Summary of Design Considerations

     The  final  design of  a sanitary  landfill should
describe in detail: (1) all  employee and operational
facilities;  (2)  operational  procedures  and their se-
quence,  equipment, and  manpower  requirements;
(3) the pollution  potential and  methods of control-
                                     -COMPACTED
                                      SOLID WASTE
     Figure 17.   In the progressive slope or ramp  method of sanitary landfilling, solid waste is spread and com-
pacted on a slope. Cover material  is obtained directly in  front of the working face and compacted on the waste.
                                                                                                  29

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ling  it;  (4) the final grade and planned use of the
completed  fill;  (5)  cost estimates  for  acquiring,
developing,  and operating the proposed site.
     The designer should also provide a  map that
shows the  location of the site and the area to be
served  and  a topographic  map covering the area
out to 1,000 ft  from the site. Additional maps and
cross-sections should also be  included  that  show
the planned stages of filling  (startup,  intermediate
lifts, and completion). They should present the de-
tails of:

        1.  Roads on and off the site;
       2.  Buildings;
       3.  Utilities above and below  ground;
       4.  Scales;
       5.  Fire protection facilities;
       6.  Surface drainage (natural  and con-
          structed)  and groundwater;
       7.  Profiles of soil and bedrock;
 8.  Leachate collection and  treatment
    facilities;
 9. Gas control devices;
10. Buildings within 1,000 ft of proper-
    ty  (residential, commercial,  agri-
    cultural);
11. Streams,  lakes, springs,  and wells
    within 1,000  ft;
12. Borrow areas  and volume of  ma-
    terial available;
13. Direction of prevailing wind;
14. Areas to  be  landfilled,   including
    special waste areas, and  limitations
    on  types of waste that may  be dis-
    posed of;
15. Sequence of filling;
16.  Entrance to facility;
17. Peripheral fencing;
18. Landscaping;
19. Completed  use.
                                            REFERENCES

                1. Community  action guidebook  for soil  erosion and  sediment control.  The
                          National Association of Counties  Research  Foundation, 1970.  66 p.
                2. HAY, W. H.  Transportation engineering.   John Wiley & Sons, Inc. New York,
                          1961. 505 p.
                3. OGLESBY, C. H., and L. I. HEWES. Highway engineering. John Wiley & Sons,
                          Inc. New York, 1963.
                4. U.S.  National Bureau of Standards.   Specifications, tolerances, and cither
                          technical   requirements  for  commercial weighing  and  measuring
                          devices adopted by National Conference on Weights and Measures.
                          Handbook 44. 3d  ed.  Washington, U.S. Government Printing Office,
                          1965. 178 p.
                5. California State Water Quality Control Board. Waste water reclamation in
                          relation to ground water  pollution.  Publication  No.  24. Sacramento,
                          1953.
                6. ANDERSON, D. R., W. D. BISHOP, and H. F. LUDWIG.  Percolation of citrus
                          wastes through soil. In Proceedings; 21st Industrial Waste Conference,
                           May 3-5,  1966. Lafayette, Ind., Purdue University, p. 892-901.
                7. HUGHES, G. M.,  R.  A. LANDON,  and R.  N.  FARVOLDEN.   Hydrogeology of
                          solid waste disposal sites in  northeastern Illinois; a  final report on a
                          solid waste  demonstration grant project. Washington, U.S. Govern-
                          ment Printing Office, 1971. 154 p.
30

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           .-*. •>•' •*, *>
            11     ijjt  <*
          5 i >-f  *
          iy*. <
sanitary   landfill   operation
    The  best designed disposal facility will be of
little value unless it is constructed and operated as
prescribed.  This  is  especially true  of a  sanitary
landfill because  it is under construction up  to the
day the last particle of solid waste is  disposed of.
Constructing the  sanitary  landfill on a daily basis
in accordance with the design should be unequivo-
cally required in an operations plan.
    An  operations plan is essentially the specifi-
cation for construction and it  should contain all
items  required to construct the sanitary landfill.
It should describe: (1) hours of operation;  (2) mea-
suring procedures;  (3) traffic  flow and unloading
procedures;  (4)  designation  of specific  disposal
areas  and  methods of handling and  compacting
various solid  wastes; (5)  placement of cover  ma-
terial; (6)  maintenance  procedures;  (7)  adverse
weather operations; (8) fire control;  (9) litter  con-
trol; (10) salvaging operations,  if permitted.
     Proper operation calls for drawing up a com-
prehensive  plan  that spells out routine procedures
and anticipates  abnormal  situations.  It must  also
provide continuity of activities even when personnel
changes  occur.   New  supervisors  and personnel
responsible for  solid  waste disposal  must know
what is being done at the landfill and why.  The  plan
must,  however,   remain  open  for revision when
necessary.  Changes  should be  noted,  and the ra-
tionale behind them explained.  New personnel will
benefit from  the  experience  of  others,  and  con-
tinuity of operations will be preserved.
    The  plan should  also be  used  as  a tool in
training employees, defining their jobs, and giving
them  an  insight  into the  work of  others. In  this
manner, the employee will more fully understand
the  overall  operation, and he may be  able to  per-
form other duties in an emergency.
Hours of Operation

     The hours a sanitary landfill  operates depend
mainly on when the wastes are delivered,  and gen-
erally this is  done during normal working  hours.
In large cities, however, waste  collection systems
sometimes operate 24 hr a day.  In this case, a site
should not be located in a residential area. The usual
landfill is open 5 to 6 days a week and 8 to 10 hr
a day.
     The hours of operation should be posted on a
sign  at the landfill entrance. It should also indicate:
what wastes are  not  accepted;  fees  charged;  and
the name, address, and telephone number  of the
operating body (sanitation  district or private com-
pany). All this information must  be  kept current.
Fees are usually  levied  on  a  cost-per-ton  basis for
large loads  and  on a  fee basis  for small amounts
brought  to  the site by  homeowners. The sanitary
landfill should be open only when operators are
on duty. If it is anticipated that waste will be brought
to a  disposal  site at other times, a large container
should be placed  outside the site entrance.
Weighing the Solid Waste

     The efficiency of filling and compacting opera-
tions can  be adequately judged  if the amount of
solid waste delivered, the quantity of cover material
used, and the volume  occupied  by the landfilled
solid waste and cover are known. (Weighing is the
most reliable means  of measurement.) These values
are also  used  to determine the density  of the fill
and to  estimate the  amount of settlement that will
probably  occur. Weight  and volume data can also
be used  in designing new landfills and  predicting
                                                                                           31

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the remaining capacity of currently operating land-
fills.
     The  number of vehicles  that can  be weighed
in a unit  of time will vary. An  experienced weigh-
master is  able to record manually, for short periods
of time, the  net weight  and types of material de-
livered at  a  rate  of  60  trucks  per  hr,  but it  is
extremely taxing to maintain  this pace for long
periods.  A  highly  automated  weighing procedure
can  easily accommodate over  60 trucks per  hr,
record more data,  require less supervision, and be
more accurate. Landfills disposing of  1,000 tons or
more per day will usually  require two  or more auto-
matic scales. Truck scales require little maintenance
if  inspected  and maintained  as recommended  by
their  manufacturers.
     Although a seemingly simple operation, weigh-
ing presents  many  problems. To ensure that  all
trucks are weighed, vehicle-handling controls and
accounting techniques  must  be developed.  Tech-
niques being used  include a two-gate system (one
at the front and one at the  back of the scale) that
locks a  truck  on the scale  until weighed, one-way
exit  barricades,  signal  lights,  curbing, alarms, and
numerous automated recording devices.
     If a  truck  is  not properly positioned on the
platform (one or more axles off) the weight recorded
will be wrong. Suitable curbing, markings, elevated
transverse bumps, or extra  long scales can reduce
or prevent unintentional misplacement of vehicles
on the scale.
     Dirt,  water, snow,  and  ice  may  accumulate
on and under the deck of the  scale and cause it to
wear and rust, lead  to hazardous driving conditions,
and generate weighing errors.

Traffic  Flow and  Unloading

     Traffic flow on the site can affect the efficiency
of daily  operations. Traffic should  be allowed to
bypass the scale only if it is inoperative. Haphazard
routing between the scale and  the disposal area can
lead to indiscriminate dumping and cause accidents.
Pylons, barricades,  guardrails, and traffic  signs can
be used to direct traffic. Large sites may need posted
maps to direct drivers.  If separate working areas are
established  for different types  of  wastes,   signs
should be used  to direct drivers to the appropriate
disposal areas.
     Wastes are delivered to  a landfill in vehicles
that range from automobiles to  large  transfer trail-
ers.  Operationally,  they  comprise groups that are
unloaded  manually or  mechanically. The  two cate-
gories are established  because of the difference  in
time  it takes to unload them at the  working face.
If large  numbers  of  manually unloaded vehicles
must be handled, special procedures may be neces-
sary.
    Mechanically discharging vehicles include dump
trucks, packer-type collection trucks,  tank trucks,
and open or closed body  trucks  equipped with a
movable bulkhead that requires the use of a crawler
dozer  or  loader.  These vehicles  are  capable of
rapidly discharging their loads and should be routed
directly to the working face without delay.
     Manually discharging  vehicles take more time
to unload and should not be permitted to  slow the
unloading of vehicles that can discharge  mechan-
ically.  Many of  the  drivers  will not be  familiar with
the landfill operation  and will require  close super-
vision. If  a  large number  of  manually discharging
vehicles is involved, a separate unloading area  may
be necessary to avoid delaying other vehicles.
     Scavenging should  not  be permitted, and no
vehicle should be left unattended. Waste should be
deposited at the toe  of the working face,  because
it can  be compacted better there since it is worked
up the slope rather than down. If  it is  necessary to
discharge solid wastes at the top of the slope, as
in a narrow trench operation, telephone  poles or
similar objects  should be emplaced to  warn drivers
that they are  near its edge. The unloading area
should be as level as practical for dump trucks and
other vehicles having high  centers of gravity in  the
raised  position.

Handling of Wastes

     Wastes come  from  residences,  commercial
establishments,  institutions,  municipal operations,
industries, and  farms.  Some may require special
methods of  handling  and  burial.  The landfill  de-
signer should  know  all  the types that will  likely
be  involved  and make provision for their disposal.
Materials that  cannot be  safely  buried  should be
excluded.
     RESIDENTIAL,  COMMERCIAL, AND  INDUS-
TRIAL  PLANT WASTES. These wastes  (exclusive of
process wastes discussed  later) are usually  highly
compactible.  They  contain a heterogeneous mixture
of such materials as paper, cans, bottles, cardboard
and wooden  boxes, plastics,  lumber,  metals, yard
clippings, food waste,  rocks, and soil. When exposed,
boxes,  plastic and  glass containers, tin  cans,  and
brush can be compressed and crushed under relative-
ly low pressure. In a landfill, however, these items are
incorporated  within the  mass  of solid waste, which
acts as a cushion and often bridges, thus protecting
the relatively  low-strength materials  from  being
crushed under the load of the compaction equipment.
     Cushioning and  bridging can  be  reduced  and
greater volume  reduction achieved if the waste is
32

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spread in layers  less than  2 ft  deep and  is then
compacted by tracked, rubber-tired, or steel-wheeled
vehicles that pass over  it 2  to 5 times. Solid waste
that contains a high percentage of brush and yard
clippings  requires the  expenditure of more  com-
pactive  effort.  If entire loads  of these items  are
received,  they  should  be spread  and  compacted
near the  bottom  of the cell so  that  less resilient
wastes can be compacted on top.
     The  equipment operator should try to develop
the working face on a  slope between  20°  and 30°
(Figure  18). Waste is spread against the slope, and
the machine moves up  and down it,  thus tearing
and  compacting  the  waste  and  eliminating voids.
The equipment operator should make passes until
he  no longer  can  detect that the surface of  the
waste  layer is  being depressed  more  than  it is
rebounding.
     BULKY WASTES.   Bulky  wastes  include  car
bodies, demolition and construction debris,  large ap-
pliances,  tree  stumps, and timbers. Significant vol-
ume reduction of construction rubble and stumps by
compaction cannot be achieved, but car bodies, furni-
ture, and appliances can be significantly reduced in
volume. A small crawler dozer (110 HP and 20,000
Ib. or less) has greater difficulty in compacting wash-
ing machines and auto  bodies than would heavy ma-
chines, but some volume reduction can be achieved.
Such items should be crushed on  solid ground and
then pushed onto the working face, near the bottom
of the cell or into a separate disposal area. Once in
place, most bulky items do not degrade (at least not
at a rate comparable to surrounding refuse). Conse-
quently, if bulky items are incorporated into degrad-
able wastes,  uneven settlement will result.  Special
areas for bulky items  should be  identified on  the
final plan of the completed  site. Even though bulky
wastes  do not  usually  contain putrescibles,  they
should be completely  covered at  the end of each
operating day to eliminate  harborage for rats and
other pests.
     Selected  loads  of demolition  and construction
    = STEPT-  Un'°.ad  '"'^^>
    .:•; •.; .'.•;••;   solid waste    ' '
    .•'•.'•.'•'.;.::':•. •.'.'•  at  toe  of  slope
     STEP 2 •'..'•..••  Spread in  thin layers
    .:...-'j;:y ••.••;•.'.•.';.'.  (approximately 2 feet)-'.
    ••Ł,™''~''/:°i:. Compact by  running  tractor
    •      ... '•'•:. over  waste layer 2 to 5 times  :
     Figure 18.  Cushioning and bridging can be reduced and greater volume reduction achieved if the waste is
 spread in layers less than 2 ft deep and is then compacted by a tracked, rubber-tired, or steel-wheeled  vehicle
 that passes over it  2 to 5 times. The equipment operator should try to develop the working face on a slope be-
 tween 20 and 30 degrees.
                                                                                                   33

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debris—broken concrete, asphalt,  bricks, and plas-
ter—can  be stockpiled and  used to build  on-site
roads.
     INSTITUTIONAL  WASTES,  Solid wastes from
schools, rest homes, and hospitals are usually highly
compactible and can often  be handled in the same
manner as  residential  and  commercial wastes  and
are often delivered  along  with them.  If  hospital
wastes  are  delivered  separately,  they should  be
spread immediately,  compacted, and  enclosed with
another layer of waste or a cover  material  because
they could contain pathogenic organisms. Pathologi-
cal wastes are  usually disposed of in a special in-
cinerator, but if  accepted, they should  be  buried
immediately  under 1  ft of  cover material. Some
States have restrictions  on  the way such  wastes
are  buried,  and  pertinent  State  laws should  be
consulted.
     DEAD ANIMALS. Dead  birds, cats, dogs, horses,
and  cows are  occasionally  delivered to  sanitary
landfills.  The burial method  is covered  by  law  in
most States. Some require  that they be immediately
incorporated into  the  landfill and covered,  others
demand  that they be  placed in a pit and covered
with lime. In general,  small animal corpses can be
safely disposed of if placed in  a landfill along  with
other wastes and  immediately covered. Very large
animals  are usually dismembered so they  can be
transported  to the  disposal  site. They  are then
placed in a  pit  and covered with 2 ft of compacted
soil;  this should  be  graded  periodically to avoid
ponding and settlement, which could be appreciable.
      INDUSTRIAL PROCESS WASTES.  Because  of
the wide variety of industrial process wastes and their
different chemical, physical, and  biological character-
istics, it  is difficult  to  generalize about  handling
them. The  best  source  of information concerning
their characteristics is the industries that produce
them. It is extremely important to evaluate the influ-
ence of these  wastes on  the  environment.  If an
industrial waste is determined  to  be  unsuitable for
disposal at  the landfill, it  should be excluded and
the respective industries notified. Another important
factor is the health and safety of landfill personnel.
      Industrial wastes delivered to  a landfill  may
be in the form of a liquid, semi-liquid, films,  sheets,
granules, shavings,  turnings, powders, and defec-
tively manufactured   products  of all shapes and
sizes. Whether or not these  are disposed of in the
sanitary landfill depends on the environmental con-
ditions of  the site  and whether or not they are
chemically  and biologically stable. They should not
be allowed  to pollute surface water or groundwater.
      Liquids and semi-liquids, if deemed  safe to
place in a landfill, should be  admixed with relatively
dry, absorbent solid waste or they may be disposed
of in  a  pit well  above the groundwater  table. The
pit should be fenced and the gate locked  to prevent
unauthorized access; its location should be recorded
in the final plan of the completed  site.
     Films and  other  light, fluffy, easily airborne
materials  can be a  nuisance  at the working  face,
and they should be covered immediately when de-
posited  there. Spraying  them  with  water  may be
helpful,  but the detrimental effects of adding water
should be  considered.
     Large sheets  of metal,  plastic, or  wood can
also be  nuisances at the working  face. The equip-
ment operator should  align the sheets  parallel to
one  another.  Random  placement  leads to  large
voids, poor compaction,  and substantial  settlement
of the completed landfill.
     Granules, shavings, turnings,  and powders can
be health  hazards to operating personnel, nuisances
if they become airborne, and  very abrasive or cor-
rosive to  the landfill  equipment; they  should be
covered immediately.
     The  workers may have to wear  face  masks,
goggles, or protective clothing to avoid respiratory,
eye, or skin ailments.
      Defectively  manufactured  products  are de-
livered to the landfill to  keep  them off the market.
These wastes should be  incorporated into the sani-
tary  landfill  immediately so that  drivers,  helpers,
and others at the working face are  not tempted  to
engage  in  scavenging. Their doing so would violate
the manufacturer's trust and,  even more important-
ly, would  expose them to injury.
     VOLATILE  AND FLAMMABLE WASTES.  Some
wastes,  such as paints, paint residues, dry cleaning
fluids, and magnesium shavings, are volatile or flam-
mable. They may be in powder, solid, or liquid form,
and they usually derive from industrial processing or
are commercial  wastes. If they are not highly flam-
mable or  volatile, they may be admixed with other
wastes, otherwise  they  should be  excluded from
the fill  or quickly  disposed of in a  separate area
at  the  site. If  the latter  step is  taken, the area
should  be clearly marked  with  warning  signs, and
its  exact  location  recorded in the final plan of the
completed  site.  Under  no  circumstances  should
smoking or open  flames be allowed  in the vicinity
of volatile or flammable wastes when they are being
disposed  of.
    WATER AND WASTEWATER TREATMENT PLANT
SLUDGES. Dewatered  sludges received  from water
treatment plants  and dewatered  digested  sludges
received from wastewater treatment plants can  be
disposed of at a sanitary landfill. In most cases, they
can be placed in the regular part of the fill, but they
should  be  covered immediately.  If their  moisture
content is  relatively high,  the sludges should  be
 34

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mixed with the other wastes before being covered
to prevent localized  leaching. Raw sewage sludges
and septic tank pumpings should not be disposed
of at a sanitary landfill.
     INCINERATOR FLY ASH AND RESIDUE. Fly ash
is a fine particulate material that has been removed
from  combustion  gases.  As  more  stringent  air
pollution control regulations are enforced, the quan-
tity of fly ash that must  be disposed of is expected
to increase. Fly ash may  be moist or dry, depending
on how it is separated from the gas stream. If it is
dry,  water may  have to be added to it so that it
does not  become  airborne and create  a nuisance.
Covering  should take place immediately. Residue
is the solid material that  remains after a combustion
process ends. The amount of decomposable organics
present in incinerator residue varies widely, but few
incinerators produce a residue low enough  in de-
composable organics to allow  it to be  used  as a
daily cover material. When the  residue dries, the
fines  can  create a  dust problem. Because  of its
moisture  and food  content, residue  may  have a
foul  odor and  attract  flies,  birds,  and  rodents.
Residue of this  nature should  be incorporated into
a sanitary landfill.
     PESTICIDE CONTAINERS. Pesticide containers
may be delivered to landfills in  agricultural areas. If
they are empty,  they can be  crushed by the landfill
equipment and disposed of along with other solid
wastes. If they are full or only  partially empty, they
should be excluded  from  the  sanitary landfill and
stored  with proper inspection to avoid environmental
insult,  pending final detoxification and disposal by
incineration or pyrolysis under carefully  controlled
time and  temperature conditions.
     ANIMAL MANURE. Another waste originating
primarily  in  agricultural  areas is  animal manure,
which often contains a large  amount of hay or bed-
ding. If the waste is not wet enough to flow, it can be
placed in the regular part of the fill  but should be
covered  immediately.  If the  moisture  content  is
high, the manure  should be mixed  with dry waste
and immediately covered.
     RADIOACTIVE WASTES  AND EXPLOSIVES.
Landfills do not accept radioactive wastes.* If any are
detected in a delivery,  the operator  should isolate
the wastes, truck, and driver and contact the proper
health  authorities.  Explosives  are  rarely delivered
to a disposal  site,  and  should be handled with
extreme caution when they are.  If they are accepted,
the operations plan should contain a provision that
explicitly outlines handling procedures, and a demo-
litions  expert should be consulted  if possible. The
exact location of the waste should be recorded on
                     TABLE 6
      Application  of Cover  Material
Cover material
Daily
Intermediate
Final
Minimum
thickness
6 in.
1ft
2ft
Exposure
time*
0-7 days
7-365 days
>365 days
    * The length of time cover material will be exposed to
     erosion by wind and rain
the final plan of the completed  site,  and security
fencing and warning signs should be erected.


Placement of Cover Material

     The operations plan should  specify what soils
are to be  used  as cover material, where  they  are
to be obtained, and how they are to be placed over
the compacted solid waste. The first two specifica-
tions are determined by the landfill designer after
he  has evaluated  the  soil  investigation  and  the
functional requirements of the cover material. Cover
materials used at  a  sanitary landfill are classed as
daily, intermediate, and final; the classification  de-
pends on the thickness of soil used. This  is deter-
mined by its susceptibility to wind and water erosion
and  its ability to  meet  certain functional require-
ments.  Guides for using the different classes  are
determined  by the length of time the cover is to
be exposed to the elements (Table 6).  In general,
if the cover is to be exposed for  more than 1 week
but less than 1  year, intermediate  cover should be
used. If the cover is to be exposed less than 1 week,
daily cover is sufficient,  and if the cover is to be
exposed longer  than  1  year final cover should be
used. All cover material  should be  well compacted.
Coarse  grained  soils  can be compacted to 100 to
135  Ib  per cu ft, fine grained  soils to 70  to 120.*
     DAILY COVER. The important control functions
of daily cover are vector, litter, fire, and moisture.
Generally,  a  minimum  compacted  thickness of 6
in. of soil  will perform  these functions. The cover
is applied to the compacted waste at  least  at  the
end of each operating day. If possible,  it should be
spread  and compacted  on the top and sideslopes
as construction of the cell progresses, thus leaving
only the working face exposed. At the end  of  the
    * Radioactive wastes are disposed of under the auspices
     of the U.S. Atomic Energy Commission.
    " Unit dry weight of compacted soil at optimum moisture
     content for Standard AASHO compactive effort.
                                                                                                  35

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operating day,  the working  face  is  also  covered.
No waste should  be exposed, and  the cover should
be graded to prevent erosion  and  to  keep water
from ponding.
     INTERMEDIATE COVER. Functions of  interme-
diate cover are the same as daily cover but include
gas control and possibly service as  a  road base. It is
applied  in the same manner as daily cover, but the
minimum compacted  depth recommended  is  1 ft.
Periodic grading and compacting may be necessary
to repair erosion  damage  and  to  prevent  ponding
of water.  Cracks  and  depressions  may  develop be-
cause of  moisture loss and  settlement of the fill,
and periodic  maintenance is required.
     FINAL COVER. Final cover serves basically the
same functions as intermediate cover,  but it  must
also  support vegetative growth. At  a  minimum,  2
ft of soil should be used, compacted  into 6-in.  thick
layers.  Such factors  as soil type and anticipated
use  of  the completed  landfill  may  require  more
than 2 ft.
     Grading is  extremely important,  and grades
should  be specified in the  landfill  design. The gen-
eral  topographic   layout of the completed landfill
surface  is attained by carefully locating solid waste
cells, but the final cover is graded and compacted
to achieve the desired configuration. Water should
not be allowed to pond on the landfill surface and
grades should not exceed 2 to 4 percent to prevent
the erosion of cover material. Sideslopes should be
less than 1 vertical to 3 horizontal. Preferably, topsoil
from the site should be stockpiled  and reserved for
placement on top  of the final cover. Since  the top-
soil will be seeded, it  should  not be highly  com-
pacted.

Maintenance

     A  properly  operated  sanitary  landfill is  dis-
tinguished from an open dump by its appearance.
The effectiveness of pollution control measures also
depends on how well the landfill is maintained  dur-
ing construction and after  completion.
     Dust  is  sometimes a problem, especially  in
dry climates and  if the soil is fine  grained.  Dust
can  cause excessive wear  of equipment, can  be a
health hazard to  personnel on the site, and can be
a  nuisance if there are residences  or businesses
nearby.
     Dust raised  from vehicular traffic can be tem-
porarily controlled by wetting down roads with water
or by using  a deliquescent chemical, such as cal-
cium chloride, if  the  relative humidity is  over 30
percent. Calcium chloride  may  be  applied  at a rate
of 0.4  to 0.8  Ib  per sq yd and then  be  admixed
with the top  3 in. of the road surface. Frequent ap-
plications are  usually  required, because calcium
chloride  is soluble  in water and  is readily leached
from the soil surface. Waste oils can also be used
as temporary dust palliatives.  Periodic  treatment
or multiple sprayings at a rate  of  0.25 to  1.0  gal
per sq yd  may be necessary. After  several treat-
ments, a  packed,  oily soil  crust  usually develops
that  has  good resistance to traffic  abrasion and is
moderately resistant to  water. Good penetration by
the oil can  be expected in more permeable soils.
Clayey soils  or tightly  knit  surfaces  may resist
penetration,  in which case  it may  be desirable to
lightly scarify the surface, apply 0.25 to 0.5 gal of
oil per sq yd, and  compact the  surface. Waste  oil,
water spraying, and calcium chloride  treatment  are
only  temporary solutions;  heavily traveled  roads
should be  covered with bituminous  or cementing
materials to  provide a more permanent  surface.
     One of  the most important aspects of main-
tenance  is litter control. A landfill  operator  who
permits litter to accumulate and  spread from  the
site  is open  to warranted public criticism.  Public
acceptance of  proposed  sanitary  landfills  will be
easier if those under construction are properly main-
tained. Blowing litter can be kept at a minimum by
maintaining a small-size working face and covering
portions  of the cell as they are constructed. Snow
fences can be positioned around the working  face
to catch  blowing paper and plastic,  but unique wind
problems may  make it  necessary to  fabricate  spe-
cially designed fencing. All  fences  used should be
portable  so that they  can be kept near  the working
face.  Personnel  should  clean up litter  periodically
every working day,  especialy near the close of busi-
ness. The  litter should be  placed  on the working
face before it is covered.
     Equipment used at a landfill  requires regular
maintenance, and the operations plan should estab-
lish a  routine preventive maintenance program for
all equipment.  Information  used  to develop  this
program  is available from the respective manufac-
turers.
     A daily  application of  cover material prevents
problems associated  with  rats,  flies,  and  birds.
These  pests  are  rarely troublesome  at  a properly
operated sanitary  landfill.
     Rats are occasionally brought  in along with the
solid  waste delivered. When the waste  is unloaded
the rats  seek cover. They are  then  buried when  the
waste  is  spread,  compacted, and covered. Infre-
quently,  rats  escape and seek protection elsewhere.
If they then  become a  nuisance,  they should be
killed by  conducting a baiting prcgram that is super-
vised by  an experienced  exterminator. Local inhabi-
tants  must  be  informed of the baiting program,
signs must be erected, and  children and pets must
36

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be kept away  from the bait stations. If strong poi-
sons are  used,  guards should  keep people away.
Generally, an  anticoagulant poison should be used
over a two-to-three week period. When no more bait
is taken, the extermination program can be termi-
nated.  Procedures for using and  making poisoned
bait  have been  developed for employment at dis-
posal sites.'-3  In no case, however, should extermi-
nation  procedures  be substituted  for daily cover.
Poisoning is  rarely 100 percent effective, and it is
only a  short-term  solution.
     If fly problems become severe in summer and
an insecticide is used, daily application is necessary,
because  the  insecticide  particle  must impinge  on
the fly. Effective insecticides are malathion,  dichlor-
vos,  naled,  dimethoate,  Diazinon,  fenthion,  and
ronnel  (Table 7).  Application of cover material as
the  cell  is  constructed  may control flies  without
using insecticides.
     Birds that are sometimes attracted  to  landfills
can  be a nuisance, a  health hazard, and a danger
to low-flying  aircraft. Various  methods,  such as
cannon fire,  have been used  to frighten the birds,
but they  become  familiar with the particular noise
and  rapidly  return.  Falcons  have  been used  with
varying success,  but  they  apparently cannot  con-
tend with seagulls. Recording the troublesome birds'
distress  call  and  playing  it  back  over a public
address  system has  also  failed.  The only way to
reduce the problem is to  make each working face
as  small as   possible and  to  cover all wastes as
soon as feasible.

Weather Conditions

     Weather can slow the construction of a sani-
tary landfill, and the operations plan should provide
detailed  instructions  on  how to operate  the landfill
during anticipated inclement periods.
     In freezing weather,  the greatest difficulty is
obtaining cover  material.  If the  frost  penetrates
below 6  in., crawler dozers or loaders equipped with
hydraulic rippers  are needed to  loosen the  soil.
If several soils are available at the  site, well-drained
soils, not as  susceptible to freezing as those that
are  poorly drained,  should be reserved  for  use as
winter cover  material.  If the frost line  goes more
than 1 ft below the surface,  cover material should
be  stockpiled beforehand. Calcium  chloride  can be
admixed into  the  soil to prevent freezing, or it  can
be  covered  with  tarpaulins  or  leaves;  tarpaulins
should  be dark to  adsorb the sun's heat. If  the
trench construction  method  is  used,  enough  soil
should be excavated during warm months to handle
the  wastes  to  be  disposed of  during  freezing
weather. The trench bottom should be sloped to one
                                                                          TABLE 7
       Insecticides for Fly  Control3
            (Outdoor space  sprays)
Insecticide
Approximate Ib per acre dosage
  required for effective kills
       (up to 200 ft)
Malathion
Dichlorvos
Naled
Dimethoate
Diazinon
Fenthion
Ronnel
0.6
0.3
0.1-0.2
0.1-0.2
0.3
0.4
0.4
end to collect rainfall, which should be pumped out
before it freezes.
     Rain can cause operational  problems. Roads
leading from  all-weather access roads to the work-
ing face can  become a quagmire and  prevent  col-
lection trucks from unloading. Roads leading to the
active working area should be passable in any/kind
of weather. Gravel, crushed stone, and construction
and demolition rubble may be applied to the surface.
Collection  trucks  that pick up  mud on the  site
should  be cleaned before leaving  it to  keep them
from dirtying the  public road system.

Fires

     No burning of wastes is permitted  at  a sani-
tary landfill,   but  fires  occur occasionally  because
of carelessness  in the handling of  open flames or
because hot  wastes  are  disposed  of.  The  use of
daily cover should keep fire in a cell that is under
construction  from spreading laterally to  other cells.
All  equipment operators  should  keep a  fire extin-
guisher on their machines at all times, since it may
be  able  to put  out  a small fire.  If the fire is too
large, waste  in the buring area must be spread out
so that water can be applied. This  is an extremely
hazardous chore,  and water should be  sprayed on
those parts  of the  machine that come  in  contact
with the  hot wastes. The  operations plan  should
spell  out fire-fighting  procedures  and  sources of
water. All  landfill personnel should be thoroughly
familiar with these procedures.
     A collection truck occasionally arrives carrying
burning  waste.  It should not be  allowed near the
                                                                                                   37

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 working face of the fill but be routed as quickly as
 possible to a safe area, away  from buildings, where
 its load can  be dumped and  the fire extinguished.
Salvage and Scavenging

     Salvaging  usable  materials from  solid waste
is laudable in concept, but it should be allowed only
if a sanitary  landfill  has been designed to permit
this operation and appropriate processing and stor-
age facilities  have  been provided. All salvage pro-
posals must be thoroughly evaluated to determine
their economic  and practical feasibility. Salvaging
is usually more effectively accomplished at the point
where waste is generated or at specially built plants.
The capital and operating costs of salvage operations
at a disposal site  are  usually high, even  if it  is
properly designed  and  operated.  If  salvaging  is
practiced, it should be accomplished at a specially
designed  facility away from  the  operating  area.
Salvaging should never be practiced at the working
face.
     Scavenging, sorting through waste  to  recover
seemingly  valuable  items,  must  be  strictly  pro-
hibited. Scavengers are too intent  on  searching to
notice  the approach of spreading and compacting
equipment, and they  risk being injured. Moreover,
some of the  items collected may be harmful, such
as food  waste,  canned or otherwise;  these  items
may be contaminated. Vehicles left unattended by
scavengers interfere with operations at the fill.
                                           REFERENCES

                1. BRUNNER, D. R., S. J. HUBBARD, D. J. KELLER, and J. L. NEWTON.  Closing
                       open  dumps.  [Washington, U.S. Government Printing Office], 1971.
                         19 p.
                2. MALLIS, A.   Handbook of pest  control. 3d ed.  New York, MacNair-Dorland
                         Company, Inc., 1960. p.  46.
                3. Public health pesticides.   Pest Control, 38(3):15-54, Mar. 1970.
38

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equipment
     There is a wide variety of equipment available
for  sanitary  landfill operations. The types  selected
will depend on the amount and kinds of solid waste
to be landfilled each day  and  on the operational
methods to be employed at a particular site. Since
money spent on equipment constitutes a large cap-
ital investment and accounts for a large portion of
operating costs, the selection should be based  on
a careful evaluation of the functions to be performed
and  the cost and  ability of various  machines to
meet the needs.

Equipment Functions

     Sanitary landfill  machines fall  into three gen-
eral  functional  categories:  (1)  those  directly  in-
volved in handling waste; (2) those used to handle
cover material; (3) those that perform support func-
tions.
     WASTE  HANDLING. The  practical and safe dis-
posal of solid waste  is the primary objective of a
sanitary landfill. Although the  handling  of  solid
waste at a landfill site  resembles an earthmoving
operation,  differences  exist  that  require  special
consideration. Solid waste is less dense, more com-
pactible,  and  more   heterogeneous  than  earth.
Spreading  a given  volume of solid waste  requires
less energy than an equal amount of soil.
     Because of its size, strength, and shape, solid
waste is not as conducive as soils to compaction
by vibration. In the main, solid waste is compacted
by the compressive forces developed by the overall
massive loading of a  landfill  machine. If maximum
compaction is desired, a large, heavy machine that
is operated in accordance with the recommendations
contained in Chapter  6  will give  better  results than
a light machine. Since repeated loading of the solid
waste improves its compaction, enough  machines
should be available that 2 to 5 compaction passes
can be made during the operating day. If it is not
possible to purchase a large machine,  spreading
the solid waste into thinner layers and making more
passes with a  lighter machine may  suffice.  The
optimum number of passes depends on the moisture
content and composition of the solid  waste. Their
exact relationships, as they affect density,  have
not, however,  been determined.
     Machines that operate on  solid waste, espe-
cially during spreading and  compaction,  are  sus-
ceptible to overheating because of clogged radiators,
to broken fuel and hydraulic lines, to tire punctures,
and to damage incurred when waste becomes lodged
in the tracks or between  the wheels and the  ma-
chine body. The various accessories that are avail-
able to help alleviate  these problems are  discussed
later in this chapter.
     COVER MATERIAL HANDLING. The excavating,
hauling, spreading, and compacting of cover material
are similar to  other  earthmoving  operations, such
as highway construction. In landfill operations, how-
ever, rigorous control  of moisture content to achieve
maximum  soil  density is not  usually  practiced,
although  it is desirable to wet a very dry soil some-
what to hold down dust and to improve  compaction.
The equipment operator who spreads and compacts
cover material should be  capable of grading it as
specified  to drain the  site.  Specific   earthmoving
requirements vary according to the topographic and
soil  conditions  present. Sand,  gravel,  and certain
loamy  clay and loamy silt soils can be  excavated
with wheeled  equipment, but tougher  natural soils
require tracked machines.  If  the natural  soil cover
is thin, underlying formations composed of weath-
ered or partially  decomposed  bedrock may make
                                                                                             39

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suitable cover  material,  but  they may  have to be
broken with a crawler equipped with a rock ripper.
Rippable materials include most uncemented shale,
thinly  interbedded   limestone  and  shale,   poorly
cemented  siltstone,  and partially decomposed gran-
itic rock types. These are, however, only generaliza-
tions, and a particular soil may be easier to excavate
or more difficult to work because soil  properties
may change significantly from season  to season.
Glacial till can usually be excavated by heavy tracked
equipment if the compact clay has a moderate to
high moisture content, as in the  spring and early
summer.  In the late summer and fall,  when  less
rain falls,  glacial tills or clay soils  of similar texture
and  composition dehydrate and become very hard
and difficult to excavate.  They must often be ripped
first.  Freezing  weather may  also require the  use
of a rock  ripper to remove the frost layer.
     SUPPORT FUNCTIONS.  A sanitary  landfill re-
quires support equipment to perform such tasks as
road construction and maintenance, dust control, fire
protection, and  possibly  to  provide assistance in
unloading operations. Road construction  and main-
tenance must be provided  so that the working face
can  be reached  in all types of  weather.  This often
requires  the adoption  of  a  dust control program
which, in turn, may  call for the use of special equip-
ment, such as a water wagon  and  sprinkler or a  salt
spreader.  Mobile firefighting equipment may be  sta-
tioned on  the site or readily available nearby. Assis-
tance  in  the  unloading  operation  may   include
emptying  collection  trucks  equipped with a movable
bulkhead and pulling out  vehicles that become stuck
near the operating face during rainy weather. Unless
there are many collection trucks  requiring assis-
tance, the spreading and compacting machine  can
handle the situation.

Equipment Types and
Characteristics

     A knowledge of the types and characteristics
of earthmoving  machines  is essential if the right
selection  is  to be  made, especially since most
machines  can perform multiple functions.
     CRAWLER MACHINES. Crawler machines are of
two  types: dozer and loader.  Other common  names
for them are: bulldozer, crawler, crawler dozer, track
loader, front end loader, and bullclam;  many trade
names are also used.  They all have good flotation
and  traction capabilities,  because their self-laying
tracks provide  large  ground  contact  areas.  The
crawler is excellent for excavating work and  moving
over unstable surfaces, but it can operate approxi-
mately only 8 mph,  forward or reverse.
     The  crawler dozer is excellent for grading and

     Figure 19.  The  crawler dozer is  excellent  for
grading and can be economically used for dozing waste
for  up to  300  ft. It should  be  equipped with a U-
shaped blade that has been fitted with a top extension
to increase its  pushing area.
can be economically used for dozing waste or earth
over distances  of  up to 300 ft  (Figure 19). It  is
usually fitted with  a straight dozer  blade for earth-
work, but at a sanitary landfill it should be equipped
with a U-shaped blade that has been fitted  with a
top extension (trash or landfill blade) to push more
solid  waste.
     Unlike the crawler dozer, the crawler  loader
can  lift materials  off the ground,  but  its  bucket
is not as wide, and  it is not able, therefore, to spread
as much solid waste. The crawler  loader is an excel-
lent excavator and  can carry soil as  much as 300 ft.
There are  two types of buckets usually used  for
sanitary  landfilling:  the general  purpose  and the
multiple purpose (Figures 20-21). The general-pur-
pose  bucket  is a  scoop of  one piece construction.
The multiple-purpose bucket, which is also  known
as a bullclam or 4  in 1,  is of two-piece construction,
is hinged  at the top, and is  hydraulically operated.
It can thus clamp  onto  such objects as tree  trunks
or telephone poles and lift  and  place them  in the
fill, or it  can crush junked  autos  or washing ma-
chines. It  is also useful  in spreading cover material.
The general-purpose and  multiple-purpose buckets
come in many sizes. Matching a bucket to a machine
should be done with the advice  of the  machine
manufacturer. A landfill  blade similar to that used
on  dozers can also be fitted to loaders.
     RUBBER-TIRED MACHINES. Both  dozers and
loaders are available with rubber-tired wheels. They
are generally faster than crawler machines (maximum
forward or reverse speed  of  about  29 mph)  but do
not excavate as well. The plausible claim has been
made that because  the weight of rubber-tired ma-
chines is  transferred to  the ground over a  much
smaller contact area, they  provide better compac-
tion,  but significant differences  of  in-place density
40

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    Figure 20.   Crawler loader with a general-purpose
bucket of  one-piece construction.  The crawler  loader
is an excellent excavator.
     Figure 21.   Crawler loader with  a  multiple-
 purpose bucket, which  is also known  as a bullclam or
 4 in 1. The bucket can clamp onto such objects as tree
 trunks and telephone poles and lift and place them in
 the  fill; it can also crush junked cars and  washing
 machines.
       Figure 22.   The rubber-tired dozer is used only
infrequently at sanitary landfills. Because of the rough
and spongy surface formed by compacted solid waste,
this  machine does  not grade as well as  a  crawler
dozer.
     Figure  23.   The  rubber-tired  loader  is usually
equipped  with a  general-purpose or multiple-purpose
bucket. Because of its high operating speed, this ma-
chine  is especially suited for putting cover material
into haul  trucks  or  carrying  it economically  for dis-
tances of  up to 600 ft.
 have not been proven.  Because their loads are con-
 centrated  more,  rubber-tired machines  have less
 flotation and  traction than crawler machines. Their
 higher speed,  however,  allows  them  to complete
 more  cycles or passes in  the same amount of time
 than a crawler machine. Rubber-tired machines per-
 form  satisfactorily  on landfill  sites  if they  are
 equipped with steel  guarded tires, called rock tires
 or landfill tires.  Rubber-tired machines can be eco-
 nomically operated at distances  of up to 600 ft.
      The rubber-tired  dozer is not commonly used
 at a  sanitary landfill. Because of the  rough and
 spongy  surface  formed by compacted solid waste
 and the concentrated  wheel loads, the rubber-tired
 dozer does not  grade as well  as a crawler  dozer.
 The flotation of the crawler dozer makes  it much
 more suitable for  grading operations. The rubber-
 tired dozer should be equipped  with a landfill  or
 trash blade (Figure 22) similar to that recommended
 for a track dozer.
      The  rubber-tired  loader is  usually equipped
 with  a  general-purpose or multiple-purpose  bucket
 (Figure  23).  A particular asset of  this  machine is
 the  high speed and mobility of its  operation. When
 it is only needed  part  time at  a sanitary landfill,
 it can be driven over public roads to perform other
 jobs.  Because of  its  high  operating  speed,  the
 rubber-tired loader is  especially  suited  for putting
 cover material  into haul trucks or carrying  it eco-
 nomically over distances of up to 600 ft.
      LANDFILL COMPACTORS.  Several equipment
 manufacturers  are marketing landfill   compactors
                                                                                                     41

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equipped with large trash blades.  In general, these
machines are modifications of road compactors and
log skidders. Rubber-tired dozers and  loaders have
also been modified. The power train and structure of
landfill compactors are similar to those of  rubber-
tired machines, and their major asset  is their steel
wheels (Figure 24). The  wheels are either rubber
tires sheathed in steel  or hollow steel cores; both
types are studded  with load concentrators  (Figure
25).
     Steel-wheeled  machines probably  impart great-
er crushing and compactive effort than do  rubber-
tired or  crawler  machines. A study  comparing a
47,000-lb steel-wheeled compactor, the same  unit
equipped with rubber tires, and a 62,000-lb crawler
dozer indicated  that  under the same  set of con-
ditions,  the  in-place dry  density  of  solid  waste
compacted  by the steel-wheeled compactor was 13
percent greater  than  that effected  by the  crawler
dozer and the rubber-tired compactor.1
     The landfill compactor  is an excellent machine
for spreading  and compacting on  flat  or  level  sur-
faces and operates fairly  well on moderate  slopes,
but it lacks traction when  operating on steep slopes
or when excavating. Its maximum achievable speed
while spreading and compacting on  a  level surface
is about  23 mph, forward and  reverse. This makes
it  faster  than  a  crawler but  slower  than  a  rubber-
tired  machine. Since  landfill compactors operate
at high speeds and  produce  good in-place  densities,
they are  best  applied when they are used only for
spreading and  compacting  solid waste and cover
material. When the cover  material is a clay,  it and
some of the solid  waste lodge between the load
concentrators  and must be  continually removed by
cleaner bars. The surface  of a soil layer compacted
with a landfill  compactor is  usually covered  by pits
or indentations formed by the load concentrators.
Numerous passes are needed to minimize the rough-
ness of the surface.
     SCRAPERS.  Scrapers are available as self-pro-
pelled and  towed  models having  a wide range  of
capacities  (Figure  26). This  type  of  earthmoving
machine  can haul cover material economically over
relatively long distances  (more than  1,000 ft  for
the self-propelled versions and 300  to 1,000 ft for
towed models). Their prime  function is to excavate,
haul, and  spread  cover  material.  Since they  are
heavy when loaded, routing them over the fill area
will help compact the solid waste. Hauling  capacities
range from 2 to 40 cu  yd.
     DRAGLINE. Large excavations can  be  made eco-
nomically with a  dragline.  Its outstanding character-
istic is its  ability to dig  up moderately hard soils
and  cast or throw them away from  the excavation.
Because  of this  feature, it can also  be used  to
    Figure 24.  In general, landfill compactors  are
modifications of road  compactors and  log  skidders.
The power train and structure are  similar to those of
rubber-tired machines.  The major asset of the  landfill
compactor is its steel wheels; it  can  probably achieve
better  compaction  than  a  rubber-tired  or crawler
machine.
spread cover material  over compacted solid  waste.
It  is particularly  useful in wetland operations. The
dragline  is most  commonly found at large landfills
where  the  trench method is  used or where cover
material  is obtained from a  borrow pit. As  a rule
42

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                           /\       /\
 Tamping
               Cleat
                           Geometric
Triangular
     Figure 25.   The wheels of a landfill compactor
are either rubber tires sheathed in steel or  hollow
steel cores; both types are studded  with load concen-
trators.
of thumb,  the boom length should  be two times
the trench  width. Buckets  used at landfills usually
range from 1 to  3  cu yd.
    SPECIAL-PURPOSE EQUIPMENT. Several pieces
of earthmoving and  road construction equipment are
put to limited use on landfills  that dispose of  less
than  1,000 tons  a day. Their purchase may  not,
therefore,  be warranted.  When  they are needed,
they can be  borrowed,  leased,  rented, or the work
can be performed under contract.
     The road grader can be used to maintain dirt
and  gravel roads on the site,  to grade  the inter-
mediate and  final cover, and to  maintain drainage
channels surrounding the fill.
     Water is  useful  in controlling  blowing litter
at the working face and control of dust from on-site
roads. Water wagons  range from converted tank
trucks to highly specialized, heavy vehicles that are
generally   used  in   road  construction  operations.
They can also be used  at the  landfill to fight fires.
     The road sweeper is a real asset at sites where
mud  is tracked onto the  public  road  system.  Its
periodic use will encourage local residents to accept
the landfill because roadways remain safe.
     ACCESSORIES. The equipment used at landfills
can  be provided  with accessories that protect the
machine and  operator and increase the effectiveness
and versatility of the machine (Table 8).
     Engine screens and radiator guards keep paper
and  wire from  clogging radiator pores and causing
the engine to overheat. A reversible fan can  also
help alleviate this  problem,  because the direction
of air flow or  vane pitch  can  be changed in  less
than 5 min.  Under-chassis guards can  be installed
to shield the engine, and  hydraulic lines and other
essential  items  of  the machine  should also  be
protected   if  they are susceptible to damage (Fig-
ure 27).
     The operator's comfort, safety,  and efficiency
can  be increased by providing roll bars, a canopy
or cab, cab or helmet air conditioning,  and backup
warning systems. A canopy is especially desirable
for machines that  operate  in  a  trench  into which
                 Figure 26.  Scrapers are available as  self-
            propelled or towed models; their prime function  is to
            excavate, haul,  and  spread cover material.  Capacities
            range from 2 to 40 cu yd.
            waste is dumped from above. Cabs are particularly
            useful when the working area  is very dusty or the
            operator must work in very cold weather. Because
            rubber-tired machines and landfill compactors oper-
            ate  at  relatively high speeds,  an audible backup
            warning system  should  be provided  to alert other
            equipment operators and  personnel  in  the imme-
            diate area. This system is  also desirable on crawler
                                                                                                  43

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                    TABLE 8
Recommended and  Optional  Accessories
            for Landfill Equipment
Dozers
Accessory Crawler Rubber-
Tired
Dozer blade
U-blade
Landfill blade
Hydraulic controls
Rippers
Engine screens
Radiator guards-hinged
Cab or helmet
air conditioning
Ballast weights
Multiple-purpose
bucket
General-purpose
bucket
Reversible fan
Steel-guarded tires
Life-arm extensions
Cleaner bars
Roll bars
Backing warning system
0*
0
Rt
R
0
R
R
0
0
—
—
R
—
—
—
R
R
0
0
R
R
—
R
R
0
0
—
—
R
R
—
—
R
R
Loaders
Landfill
Crawler Rubber- corn-
Tired pactor
—
—
0
R
0
R
R
0
R
R
0
R
—
0
—
R
R
—
—
0
R
—
R
R
0
R
R
0
R
R
0
—
R
R
0
0
R
R
—
R
R
0
R
—
—
R
—
—
R
R
R
" O, Optional.
t RF Recommended
 machines, especially when two or more are operat-
 ing in the same area.
      Equipment versatility  and  effectiveness can
 be increased  by use of a  number of accessories.
 A hydraulically operated ripper is needed  when
 extensive excavation  must be carried  out  in  hard
 soils.  It  should be mounted on  a tracked machine
 to take  advantage of its greater traction.  (Back-
 rippers,  hinged teeth attached to buckets or blades
 that dig  into the soil when the machine is reversing,
 are  not  as  effective as hydraulically  operaed  rip-
                                                        Figure 27.  The equipment used at sanitary land-
                                                   fills can be provided with accessories that protect the
                                                   machine and operator and increase their effectiveness.
pers.) To give  rubber-tired  machines  and landfill
compactors  more  traction,  their  wheels  can be
ballasted with a calcium chloride solution or water,
and steel or concrete counterweights can be used
on loaders and  landfill compactors.
     Different  power trains can  be used on  many
large machines. The power shift and torque conver-
ter options are  preferable  to the dry clutch, direct-
drive  models because greater speed of operation
and  less  strain on the engine  and  operator  are
possible  with them.
     COMPARISON OF CHARACTERISTICS. The abil-
ity of various machines to perform the many functions
that must be carried out at a sanitary landfill should
be analyzed with respect to the needs and conditions
of each  site  (Table 9). General  recommendations
regarding the best types and sizes of machines to
use at a specific landfill can be  misleading. More
exhaustive analysis is  needed  before the  final equip-
ment selection is made.

Size of Operation

     Definition of functions and evaluation of equip-
ment  performance must be matched with the size
of the  landfill  to determine the type, number, and
size  of  the machines needed. No one  machine is
capable  of performing all functions  equally  well.
Neither can it  be  assumed that  equipment  effec-
tively used at  one  site will  be  the most  suitable
elsewhere. Unfortunately, production rates expressed
in tons of solid waste spread and compacted per
hour  are  not  readily  available   for  comparison.
Guides that have been proposed by equipment man-
ufacturers and others should be considered only
rough estimates of equipment needs for  a particular
landfill  (Table 10).
     SINGLE-MACHINE SITES.  Particular difficulty
is encountered  when selecting equipment for a site
 44

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                                               TABLE 9
                  Performance Characteristics  of  Landfill  Equipment*!
Equipment
Crawler dozer
Carwler loader
Rubber-tired dozer
Rubber-tired loader
Landfill compactor
Scraper
Dragline
Solid
Spreading
E
G
E
G
E
NA
NA
Waste
Compacting
G
G
G
G
E
NA
NA

Excavating
E
E
F
F
P
G
E
Cover
Spreading
E
G
G
G
G
E
F
Material
Compacting
G
G
G
G
E
NA
NA

Hauling
NA
NA
NA
NA
NA
E
NA
   * Basis of evaluation: Easily workable soil and cover material haul distance greater than 1,000 ft.
   t Rating Key: E, excellent; G, good; F, fair; P, poor; NA, not applicable.
                                               TABLE 10
                                   Landfill  Equipment  Needs3
Solid
waste handled
(tons/8 hr)
0-20
20-50


50-130


130-250


250-500


500-plus
Crawler loader
Flywheel Weight*
horsepower (Ib)
<70 < 20,000
70 20,000
to to
100 25,000
100 25,000
to to
130 32,500
150 32,500
to to
190 45,000
combination of
machines

COME
Crawler
Flywheel
horsepower
<80
80
to
110
110
to
130
150
to
180
250
to
280
H N A T 1 0 N
dozer
Weight*
(Ib)
< 15,000
15,000
to
20,000
20,000
to
25,000
30,000
to
35,000
47,500
to
52,000
0 F M A C
Rubber-tired loader
Flywheel Weight*
horsepower (Ib)
<100
100
to
120
120
to
150
150
to
190



H 1 N E S
< 20,000
20,000
to
22,500
22,500
to
27,500
27,500
to
35,000
combination of
machines


    Note:    Compiled from assorted promotional material from equipment manufacturers and based on ability of one machine
m stated class to spread, compact, and cover within 300 ft of working face
    ' Basic weight without bucket, blade, or other accessories.
where  only one machine will be used.  It must be
capable of spreading and  compacting both  solid
waste and  cover material, but it may also have to
be  used to excavate  trenches or cover  material.
In general, the most versatile machine  for a small
landfill  is  the  tracked  or rubber-tired  loader. If the
machine will not be used full time, a wheeled loader
is preferable because of  its  mobility. If the machine
is to stay at the  site  full  time  and will  not  be
required to load cover material into trucks, a  crawl-
er dozer may be better.
     Regardless of  the size of  a  single-machine
operation, the dependability of the machine should
be high. Arrangements should be made in advance
to obtain a  replacement  if  a  breakdown occurs,
because this development is no excuse for unaccept-
able disposal. A replacement machine  may be made
available  through  the  equipment dealer,  a  local
                                                                                                    45

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                                              TABLE 11

                                     Machine  Capital Cost
Equipped Machine
Machine type
Crawler dozer


Crawler loader




Rubber-tired loader



Flywheel
Horsepower
<80
110-130
250-280
<70
100-130
100-130
150-190
150-190
<100
<100
120-150
120-150
Weight
(Ib)
< 15,000
20,000-25,000
47,500-52,000
< 20,000
25,000-32,500
25,000-32,500
32,500-45,000
32,500-45,000
< 20,000
< 20,000
22,500-27,500
22,500-27,500
Approximate
weight*
(Ib)
19,000
32,000
67,000
23,000
31,000
32,000
45,000
47,000
17,000
18,000
23,000
26,000
Approximate
costf
($)
21,000
38,000
70,000
21,000
30,000
32,000
46,000
49,000
21,000
23,000
33,000
36,000
Comment
landfill blade
landfill blade
landfill blade
GPBJ— 1 cu yd
GPB —2 cu yd
MPB**—l3/4cuyd
GPB— 3 cu yd
MPB-2i/2 cu yd
GPB-13/4 cu yd
MPB-iy2 cu yd
GPB— 4 cu yd
MPB-21/4 cu yd
    * Basic machine plus engine sidescreens, radiator guards,  reversible fan, roll bar, and either a landfill blade, general-purpose
     bucket, or multiple-purpose bucket as noted.
    tJune 1970.
    t General-purpose bucket.
   " Multiple-purpose bucket.
contractor, or a municipal public works department.
     SMALL SITES. Municipalities disposing of less
than 10 tons a day may find the cost of owning a
small dozer or loader too high. If excavation and
stockpiling of cover material are done on contract,
a farm tractor equipped with a blade or bucket may
be  sufficient for spreading the  solid waste. The
tractor will not, however,  be able to produce much
compaction, even  if  the  waste is spread  in thin
layers. The poor  compaction achieved means that
a larger fill area will  be needed. This  requirement,
together  with the  total cost of the  contract work,
should be  compared to the  expense of owning and
operating a small dozer or loader.
     MULTIPLE-MACHINE OPERATION. It is easier
to select equipment for a multiple-machine operation
than it is fora one-machine operation. Such special-
ized machines as scrapers and landfill compactors
may then  be economical  to use. If cover  material
has been  stockpiled and more than one machine is
available, operations  need not be  interrupted when
an equipment breakdown  occurs. As an added pre-
caution,  replacement  machines should be available
through a lease, contract, or borrowing arrangement.

Costs

     The equipment selected for a sanitary landfill
must not only be able to perform  well under con-
ditions present at the site, it must also  do so at
the least total cost.  Equipment  costs, both capital
and  operating, represent a  significant portion of
the expenses incurred  in operating a  sanitary land-
fill.
     CAPITAL COSTS.  Except for land, the cost of
equipment may be the greatest portion of  initial ex-
penditures. The sanitary landfill equipment market is
very competitive,  but rough approximations of costs
have been developed (Table 11). A crawler machine
weighing 29,000  Ib without accessories costs about
$29,000. With engine sidescreens, radiator guards,
reversible fan,  roll  bar, and a  multiple-purpose
bucket, the  same  machine  costs   approximately
$32,000. A new dragline can cost between $75,000
and $110,000 depending on  the length of its  boom
and  cables, and the size of  its  bucket. In general,
most landfill equipment used  for excavating, spread-
ing, and  compacting has a useful life of 5 years or
10,000 operating hours.
     The price of a  used  machine depends on its
type, size, condition, and number of recorded oper-
ating  hours.  Specific  resale values are  available
from auctioneers  and manufacturers of  earthmov-
ing equipment. The condition and  remaining useful
life of used  equipment should be  determined by
an expert.
     OPERATING AND MAINTENANCE COSTS. Pur-
chases of fuel, oil, tires, lubricants,  and filters and
46

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any expenses  associated with routine  maintenance
are considered operating costs. Expenditures on fuel
account for approximately  90 percent  of operating
costs.  The expense  of operating dozers,  loaders,
and landfill compactors varies according to type and
make;  the manufacturer should, therefore, be con-
sulted  for  specific estimates. Generally speaking,
direct operating costs are $3.00 per hour. The skill
of  the  equipment operator,  the  type of  waste
handled, topography, and soil conditions also affect
operating costs.
     Maintenance  costs, parts,  and labor also vary
widely  but  can be approximated by spreading one-
half the initial cost of the  machine over its antici-
pated useful life (10,000 hr). To make these costs
more  predictable, most equipment dealers  offer
lease agreements and maintenance contracts.  Long
downtimes usually associated  with major  repairs
can  be reduced by taking advantage  of  programs
offered by most equipment dealers.
     High operating costs are frequently associated
with low  initial  costs  of the equipment  and  vice
versa.  The purchaser should, therefore,  require that
equipment bids  include estimated operating costs.
     Actual operating  and  maintenance  expenses
should be determined during site operation by use
of a cost  accounting system.2 This  information can
be used to identify areas where costs  may  be re-
duced; excessive  fuel  consumption,  for  example,
may mean the machine  needs adjustment  or  that
operating   procedures  should  be  modified.  Data
from the  cost accounting system can  be used to
more accurately predict operating and  maintenance
costs.
                                           REFERENCES

               1.  STONE, R., and  Ł. T. CONRAD.  Landfill  compaction  equipment efficiency.
                         Public Works, 100(5):111-113, May 1969.
               2.  ZAUSNER,  E.  R.   An accounting  system  for  sanitary  landfill  operations.
                         Public Health  Service  Publication No. 2007. Washington, U.S.  Gov-
                         ernment  Printing Office, 1969.  18 p.
                                                                                                 47

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completed   sanitary   landfill
     Reclaiming  land  by  filling and  raising  the
ground surface is one of  the greatest benefits of
sanitary landfilling. The completed sanitary landfill
can be used for  many  purposes,  but  all  of them
must be planned  before operations begin.

Characteristics

     The designer should  know the purposed  use
of the completed  sanitary  landfill before he begins
to work. Unlike an earthfill, a sanitary  landfill con-
sists of cells containing a great variety  of materials
having different physical,  chemical,  and  biological
properties.  The decomposing solid waste imparts
characteristics to the fill that are peculiar to sani-
tary landfills. These characteristics require that the
designer plan for gas and  water controls,  cell con-
figuration, cover  material  specifications (as deter-
mined by the planned use), and the periodic main-
tenance needed at the completed  sanitary landfill.
     DECOMPOSITION. Most of the materials in a
sanitary landfill will decompose, but at varying rates.
Food  wastes  decompose  readily,  are moderately
compactible, and form organic  acids that aid de-
composition. Garden  wastes are resilient  and diffi-
cult  to compact  but  generally decompose rapidly.
Paper products and  wood decay at a  slower  rate
than food wastes. Paper is  easily  compacted  and
may be pushed  into voids,  whereas lumber,  tree
branches,  and stumps are difficult to compact  and
hinder the compaction of adjacent wastes.  Car
bodies, metal containers, and  household appliances
can  be compacted and will  slowly rust in the fill
with the help of organic acids produced by decom-
posing food wastes. Glass and ceramics are usually
easily compacted but do not degrade in  a landfill.
Plastics and rubber  are resilient and difficult to
compact; rubber decomposes very slowly, most plas-
tics not at all. Leather and textiles  are  slightly
resilient but can be compacted; they  decompose,
but at  a much  slower rate than garden and food
wastes.  Rocks, dirt, ashes, and construction rubble
do not decompose and  can  be easily  worked and
compacted.
    DENSITY. The density of solid waste in a landfill
is  quite variable. One that is well constructed can
have an in-place density as great as 1,500 Ib per
cu yd,  while that of poorly compacted solid waste
may be only 500. Generally,  800 to 1,000 Ib per
cu yd  can  be achieved with a  moderate compactive
effort.  Soft and  hard spots occur within the fill as
a result of  different decomposition rates and com-
paction  densities. Density  influences  such  other
characteristics as settlement and bearing capacity.
    SETTLEMENT. A sanitary landfill will settle as a
result   of waste decomposition,  filtering of fines,
superimposed loads, and its own weight.  Bridging
that  occurs during  construction  produces voids.
As the waste  decomposes,  fine particles from the
cover  material  and  overlying solid waste often sift
into these  voids. The weight of the overhead waste
and cover  material helps consolidate the fill, and
this development  is  furthered  when  more  cover
material is  added or a structure or roadway is con-
structed on the fill.
    The most  significant cause of settlement is
waste   decomposition, which  is greatly influenced
by the amount  of water in the fill. A landfill will
settle  more slowly if only limited water is available
to decompose the waste chemically and biologically.
In Seattle,  where rainfall exceeds 30 in. per year,
a 20-ft fill settled 4 ft in the first year after it was
completed.1 In Los Angeles, where less than 15 in.
of rain falls per year, 3 years after a landfill had
48

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been completed a 75-ft  high area had settled only
2.3 ft,  and another  section that had been  46 ft
high had settled a mere 1.3 ft.2
     Settlement also depends on the types of wastes
disposed of, the volume of cover material used with
respect to the volume of wastes disposed of, and
the compaction  achieved during  construction. A fill
composed only of construction and demolition debris
will not settle as  much  as  one that is constructed
of residential  solid  wastes. A  landfill constructed
of highly compacted waste will settle  less  than one
that is poorly  compacted.  If two landfills contain
the same types of wastes  and are  constructed  to
the same height, but one has  a  waste-to-cover vol-
ume ratio of 1:1 and the other  a ratio of 4:1,  the
first will settle  less.  Because  of the  many factors
involved, a fill  may settle as much  as 33  percent.3
     Settling can produce wide cracks in the cover
material that  expose the wastes to rats and flies,
allow water to  infiltrate, and permit gas to escape.
Differential settling may form depressions that per-
mit water  to  pond  and infiltrate the fill.  Settling
may also cause structures on the landfill  to  sag
and  possibly collapse; the underground utility lines
that serve these buildings or traverse the site may
then shear. Because every landfill  settles, its sur-
face  should  be  periodically  inspected  and  soil
should be added and graded when necessary.
     BEARING CAPACITY. The bearing capacity of a
completed sanitary  landfill is the  measure  of  its
ability in pounds per square foot to  support founda-
tions and keep them intact. Very little information
is available on the subject, but  a few investigators
place  the  bearing capacity of a completed  landfill
between 500  and 800  Ib per  sq ft";  higher values
have,  however,  been  noted.5 Since there is no defi-
nite procedure for interpreting the  results of solid
waste  bearing tests,  any value obtained should  be
viewed with extreme  caution. Almost without excep-
tion, the integrity and bearing capacity of soil cover
depend on the underlying solid waste. Most bearing
strength tests of soil are  conducted over a short
period—several  minutes for  granular materials to
a maximum of 3 days for clay having a high mois-
ture or air content. During the test,  the soil adjusts
to its  limits under the load imposed and conditions
of confinement. Solid waste, on the other hand does
not follow this pattern of deformation  but continues
to alter its structure and  composition over a long
period  of time. Natural soils,  which  are  not  as
heterogeneous as solid  waste,  produce test values
that fall within a predictable  range.  Moreover,  re-
peated tests of the soil  will produce similar results
—similar  relationships  have not been established
for solid waste.
     LANDFILL GASES. Landfill gases  continue to be
produced  after the  landfill is completed  and  can
accumulate  in structures or soil, cause  explosions,
and stunt or kill  vegetation.6  Placement of a thick,
moist, vegetative, final cover may act as a gas-tight
lid that forces gases to migrate laterally  from the
landfill. If the site is converted into a paved parking
lot, this  may  also prevent the gases from venting
into the atmosphere. Design of gas controls should,
therefore, conform  with the planned  use  of the
completed fill.
     CORROSION. The decomposing  material in a
landfill is very corrosive. Organic acids are produced
from  food,  garden,  and  paper wastes, and some
weak  acids are  derived  from ashes.  Unprotected
steel  and  galvanized  pipe used  for utility lines,
leachate  drains, and building foundations are sub-
ject to severe and rapid  pitting. All  structural  ma-
terials susceptible to corrosion should be protected.
Acids present in a saintary landfill  can deteriorate
a concrete surface and thus expose the reinforcing
steel; this could eventually  cause the  concrete to
fail.

Uses

     There  are  many ways  in which a completed
sanitary  landfill can  be used; it can, for example,
be converted  into a green area or be designed  for
recreational, agricultural, or light construction pur-
pbsesTTfnrTario'fin  designer  should evaluate each
proposal from a  technical and economic viewpoint.
More suitable land is often available elsewhere that
would not  require the expensive construction tech-
niques required at a sanitary  landfill.
     GREEN AREA. The use of a completed sanitary
landfill as a  green area  is very common. No expen-
sive structures  are built, and  a grassed area  is
established   for  the pleasure of  the  community.
Some  maintenance  work  is,  however,  required to
keep  the fill  surface  from being  eroded  by wind
and water. The  cover material should be graded to
prevent water from ponding and  infiltrating the fill.
Gas and water monitoring stations,  installed during
construction,  should be  periodically sampled until
the landfill  stabilizes. Gas and water controls and
drains also require periodic  inspection and main-
tenance.
      If the final cover material is thin, only shallow-
rooted grass,  flowers, and shrubs should be planted
on the landfill surface. The decomposing solid waste
may be toxic to plants whose roots penetrate through
the bottom  of the final cover. An accumulation of
landfill gas in the root zone may  interfere with the
normal  metabolism  of  plants. This  can be avoided
by selecting a cover material having a low  water-
holding capacity, but this type of soil provides poor
                                                                                                    49

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support for vegetation.  On the other hand, a  moist
soil does  not  allow decomposition  gas to disperse
and consequently  gas venting must be considered.
     The most commonly used vegetation is grass.
Most  pasture  and  hay  grasses are shallow-rooted
and can be used  on a  landfill having only 2 ft of
final cover, but alfalfa  and clover  need  more than
this. The  soil  used for final  cover influences  the
choice of vegetation. Some  grasses,  such as  tall
meadow oat grass, thrive well  on light sand  or
gravelly soils,  while others, such as timothy grass,
do better  in such  heavier soils as clays and  loams.
     Climate  also  influences  the   selection   of
grasses. Bermuda  is a good soil binder and thrives
in  southern States. Perennial rye does best where
the climate is  cool and  moist and winter  is mild;  it
roots  rapidly   but  dies off   in  2 to  3  years  if
shaded. Redtop and bent grass thrive almost any-
where except in drier areas and the extreme south.
The selection  of the grass or mixture of grasses
depends,  therefore,  on  climate, depth of the root
system, and soil used  for  cover material.*  Mowing
and  irrigating  requirements  should  also be  con-
sidered. In general, it is not advisable to irrigate the
landfill surface, because the water may infiltrate and
leach  the fill.
     AGRICULTURE. A completed  sanitary  landfill
can be made productive by turning it into  pasture or.
crop land.  Many  of the grasses  mentioned above
are suitafjTe for hay production. Corn and wheat
usually  have 4-ft  roots, but  the  latter occasionally
has longer ones. The depth of the final cover must,
therefore, be increased accordingly.
     If  cultivated  crops are  used, the final cover
should be thick enough that roots or cultivating do
not disturb its bottom  foot.  If the landfill is to be
cultivated, a 1- to 2-ft layer of relatively impermea-
ble soil, such  as clay,  may be placed on  top of the
solid waste and an additional layer of agricultural
soil placed above to prevent the clay from drying
out. Excessive  moisture will also  be prevented from
entering the fill. Such a scheme of final cover place-
ment  must also provide for  gas venting  via gravel
trenches or pipes.
     CONSTRUCTION. A foundations engineering ex-
pert should be consulted if plans call for  structures
to be built on or near a completed sanitary landfill.
This  is  necessary  because  of  the  many  unique
factors  involved—gas movement, corrosion, bearing
capacity, and settlement. The cost of designing, con-
structing, and  maintaining buildings is considerably
higher  than  it is for  those erected on a  well-
compacted  earth  fill or  on  undisturbed  soil.  The
    * Information on the grasses mainly used in a landfill area
     is available from county agricultural  agents  and the
     U.S. Soil Conservation Service.
most  problem-free technique is to preplan  the  use
of islands to avoid settlement,  corrosion, and bear-
ing-capacity problems. Ideally, the islands should be
undisturbed soils that are bypassed during  excavat-
ing and  landfilling  operations.  Settlement would
then be governed by the normal  properties of the
undisturbed soil. Alternatively,  truck loads of rocks,
dirt, and rubble could be laid down and compacted
during construction of the landfill at  places where
the proposed structure would be built.
     The decomposing landfilled waste  can be ex-
cavated and replaced with compacted rock or soil fill,
but this method  is very  expensive and could  prove
hazardous to the construction workers. The decom-
posing waste emits a very putrid smell, and hydrogen
sulfide, a  toxic gas,  may be  present  with methane,
an  explosive gas.   These two  gases  should  be
monitored throughout the excavating operation.  Gas
masks may have to be  provided  for the workmen,
and no open flames should be permitted.
     Piles  can also  be  used to support buildings
when  the piles  are  driven completely through the
refuse to firm soil or  rock. Some of the piles should
be battered  (angled) to resist lateral movement  that
may occur in the fill. Another  factor to  consider  is
the load  imposed on the piles by  solid  wastes  set-
tling around them. The standard  field  penetration
resistance test is used to determine the strength of
the earth  material  in  which the  piles are to be
founded.  During this test, penetration  will be re-
sisted  by the solid waste, but as the refuse decom-
poses  and settling  occurs, it may no longer resist
and will more likely create a  downward force on the
pile. There  are  no data  for established procedures
for predicting this change  in  force.
     Several  peculiar problems  arise  when  piles
are used to support a structure over a landfill. The
decomposing waste  is very  corrosive,  so the  piles
must  be protected with corrosion-resistant coatings.
It may be very difficult to drive the piles  through the
waste  if large bulky items, such as junked  cars and
broken concrete, are in  the fill where the structure
is to be located. The  fill  underlying a pile-supported
structure  may settle, and  voids or air spaces  may
develop between the landfill surface and the bottom
of  the structure. Landfill  gases  could  accumulate
in these voids and create an explosion hazard.
     Light,  one-story buildings are sometimes  con-
structed on the landfill surface. The  bearing capac-
ity of the  landfill  should be  determined  by  field
investigations in order to design continuous founda-
tions.  Foundations should be  reinforced to bridge
any gaps  that  may  occur because of differential
settling in the fill. Continuous floor slabs reinforced
as  mats can  be  used, and the structure should be
designed  to accommodate settlement.  Doors,  win-
50

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dows,  and partitions  should  be able to  adapt to
slight differential movement between them and the
structural framing. Roads, parking  lots, sidewalks,
and  other paved areas should be constructed of a
flexible and  easily repairable  material,  such  as
gravel  or  asphaltic concrete.
     Consolidating  the landfill to improve its bear-
ing capacity and reduce settlement  by surcharging
it  with  a  heavy layer  of  soil  does  not directly  in-
fluence the decomposition  rate.  If the  surcharge
load is removed and  the structure  is  built before
the waste has  stabilized, settlement will still  be a
problem, and  the bearing capacity  may not  be as
great as expected.
     None of  the methods for supporting  a  struc-
ture over a landfill are problem-free. A common dif-
ficulty  is keeping landfill gases from accumulating in
the  structure.  Even  buildings  erected on undis-
turbed islands of soil must be specially designed to
prevent this from developing. A  layer of sand  can
be laid  over the proposed structural area and then
be covered by two or more layers of polyvinyl chlo-
ride sheeting.  An additional layer of sand  can then
be  emplaced.  If the  bottom  layer of sand is  not
saturated, it will act as a gas-permeable vent, and
the sheeting will prevent  the  gas from entering or
collecting under the  structure.  The  top  layer of
sand protects the sheeting from being  punctured.
Another approach is to place an impermeable mem-
brane  of  jute  and asphalt under  all  below-grade
portions of the structure. A gravel or sand layer must
underlie the jute-asphalt membrane and be vented
to the  atmosphere. The most  reliable  method  is to
construct  a ventilated  false basement to keep  gas
from accumulating.
     Utility connections must  be made gas proof if
they enter a structure below grade. If the building is
surrounded by filled land, utility lines that traverse
the fill  must  be flexible, and  slack  should be pro-
vided so the lines can adjust to settlement. Flexible
plastic  conduits  are  more  expensive than  other
materials but would  probably work  best,  because
they are elastic and  resist corrosion.  Gravity waste-
water pipelines  may  develop low points  if the fill
settles.   Liquid wastes should  be  pumped  to  the
nearest sewer unless the grade from  the  structure
to the  sewer prevents  low points from  forming.
Shearing of improperly designed water and waste-
water services caused by differential settlement  can
occur where they enter the  structure or  along  the
pipeline  that traverses the fill.
     RECREATION.  Completed  landfills  are often
used as ski slopes, toboggan runs, coasting hills,  ball
fields,  golf courses,  amphitheaters,  playgrounds,
and  parks. Small, light buildings, such as conces-
sion  stands,  sanitary facilities,  and  equipment
storage sheds, are usually required at recreational
areas.  These  should  also be constructed  to keep
settlement  and gas problems at a minimum.  Other
problems encountered are  ponding,  cracking,  and
erosion  of cover  material. Periodic  maintenance in-
cludes regrading, reseeding, and replenishing  the
cover material.
Registration

     The completed  landfill should be inspected  by
the governmental  agency  responsible for ensuring
its proper operation. Following final  acceptance of
the site, a  detailed description,  including a  plat,
should be recorded with the proper authority in the
county  where the  site  is  located.  This provides
future  owners or users  with  adequate information
regarding the previous use of the  site. The descrip-
tion  should, therefore,  include  type and general
location  of  wastes,  number  and  type of  lifts, and
details about the original terrain.
                                            REFERENCES

               1. DUNN, W. L.  Settlement and temperature of a covered  refuse dump. Trend
                         in Engineering (University of Washington), 9(1):19-21, Jan. 1957.
               2. County of Los Angeles,  Department  of County Engineer  and Engineering-
                         Science, Inc.   Development of construction and use criteria for sani-
                         tary  landfills;  an  interim  report. Cincinnati, U.S.  Department of
                         Health, Education, and Welfare, 1969. [267 p.]
               3. Refuse volume reduction in a sanitary landfill.  Journal of the Sanitary Engi-
                         neering Division, Proc. ASCE, 85(SA6):37-50,  Nov.  1959.
               4. SOWERS, G.  F.   Foundation problems in sanitary landfills. Journal  of the
                         Sanitary Engineering Division, Proc.  ASCE, 94(SA1):103-116,  Feb.
                         1968.
               5. ELIASSEN, R.   Load-bearing characteristics of landfills. Engineering  News-
                         Record,  129(11):103-105,  Sept. 10, 1942.
               6. How to use your completed landfills.  American City, 83(8):91-94, Aug. 1965.
                                                                                                   51

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management
     The size and scale of operations carried out at
a sanitary landfill and the area served will influence
the mechanics of management. The purpose and
goal of solid waste managers should  be to  con-
solidate and coordinate all the resources necessary
to dispose of solid wastes in the most  sanitary
and efficient manner possible.

Administrative Agency

     The responsibility for operating a sanitary land-
fill  is normally determined  by the community ad-
ministrative  structure  involved, and it must do  so
in the light of its own  circumstances.
     MUNICIPAL OPERATIONS. In most municipal
operations, administrative responsibility is assigned
to the department of  public works,  one  of whose
divisions manages the  solid  waste program. As the
scope of  this division's activities  increases,  it is
desirable  to subdivide  the division  into functional
sections.  Regradless  of  organizational  structure,
collection  and disposal plans  and operations must
be coordinated to achieve satisfactory and economi-
cal solid waste management.
     SPECIAL DISTRICTS. Many States have enabl-
ing legislation that permits the formation of special-
purpose  districts, which  can include solid  waste
disposal districts. These districts are advantageous
in that  they can serve many  political jurisdictions
and may have provisions for levying special taxes.
Before any special district is considered,  the State
laws applicable to them should be investigated.
     COUNTY OPERATIONS. A sanitary landfill ad-
ministered by a county may  have advantages over a
municipal operation. A county operation could serve
a number of incorporated and unincorporated areas
using  existing   governmental  apparatus,  and  it
might allow comprehensive planning  for a  larger
geographic  area.  Other advantages are economy of
scale and greater availability of land.
     PRIVATE OPERATIONS. Many sanitary landfills
are operated successfully by private industry under a
contract, franchise, or permit arrangement.  In con-
tract operations,  the municipality  contracts with
the operator to dispose of  its solid waste for a fixed
charge per ton or load.  The municipality  usually
guarantees  that the contractor will receive a certain
minimum amount of money. Franchises usually grant
the operator permission to dispose of wastes from
specified areas and charge regulated fees. Permits
allow the operator to accept wastes  for disposal
without regard to source.
     Private operations may be beneficial to munic-
ipalities that have limited funds, but the community
must  not shirk its responsibility for  proper solid
waste disposal. Of the three methods, contract op-
erations generally give  the municipality the best
guarantee  that  solid  wastes  will be  disposed  of
properly because standards can be written into the
contract.1 Franchises  usually provide the next best
control of operation.

Administrative  Functions

     An administrative  agency is responsible for
proper solid  waste disposal, including planning,
designing,   financing, cost  accounting, operating,
recruiting and training, informing the public, and
establishing minimum disposal standards.
     FINANCES.  Sanitary  landfill capital costs  in-
clude land,  equipment, and site improvements. Op-
erating costs include salaries, utilities, fuel, and
equipment  maintenance.  Equipment  and  mainte-
nance costs were discussed in Chapter 7.
52

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     There are  several sources  of  funds to meet
capital  and operating  costs.*  The  general  fund,
derived from taxes, normally cannot  provide enough
money to meet  capital costs  but is often used to
pay for operating expenses. There  are advantages
to using the general fund for this purpose. The ad-
ministrative procedures and extra cost of billing and
collecting are eliminated.  Since all  the  taxpayers
help pay for  the sanitary  landfill,  they  are more
likely to use the  sanitary landfill rather than an open
dump.
     Using  general funds  for  landfill  operations
does, however,  have  disadvantages.  Cost account-
ing and other  administrative procedures may be so
relaxed disposal costs are difficult or impossible to
determine, and users may  have  to be monitored. It
may also be extremely difficult for solid waste man-
agement operations to get money from the general
fund because  of the  low priority often  assigned to
them.
     General  obligation borrowing  is  a  common
method of financing the capital  costs of  a sanitary
landfill. This type of bond  generally carries a  low
interest  rate  but is easily  marketed because  it is
secured  by the  pledge of real estate taxes and be-
cause  all of the real  estate within  the taxing  dis-
trict serves as  security for  the  borrowed  funds.
State statutes usually limit the amount  of debt a
community can  incur.  If the  debt is already  sub-
stantial, this method  may not  be available. In some
cases,  general  obligation  bonds  are retired  with
revenues generated by the landfill  operation; this
minimizes the ad valorem taxes  necessary for bond
retirement.
     Revenue  bonds  differ  from general  obligation
bonds in that they are secured only by  the ability
of the project to  earn enough to pay  the  interest
and retire the bonds.  In this case, fees must be
charged to landfill users in amounts necessary to
cover all capital  and operating expenses. It is neces-
sary to set the  fees  high enough to accumulate a
surplus over and above debt service needs in order
to  make the  bonds  attractive to prospective  pur-
chasers. This  method of financing requires that the
administering  agency follow good  cost accounting
procedures, and it allows the  agency to be the sole
beneficiary of cost saving  procedures.  In addition,
the producer of  solid waste is  forced to pay the true
cost of its disposal.
     User  fees  are primarily a source of operating
revenue, but a municipality  might also employ them
     Additional information is available from Solid Waste Man-
     agement'  Financing,  one of a series of guides developed
     by the National Association of Counties Research Foun-
     dation
to generate funds for future capital expenditures.
The fees can be adjusted to cover not only the op-
erating  and capital  costs  of present landfills  but
also  to  provide a surplus  for acquiring land and
equipment.  Fees  do not provide the capital outlay
needed to start a  sanitary landfill.
     Although fees necessitate  more work  and ex-
pense because of the weighing,  billing,  and collect-
ing involved, these requirements provide an insight
into the management and  operation of  the  landfill.
Commercial haulers  are usually  billed on a  per ton
basis. Since the  individual loads from  homes are
small, the users  are charged on  a  per load basis
to reduce weighing  and  bookkeeping. Because fee
operations require that  collection vehicles be re-
corded at the  gate, this provides an additional con-
trol over wastes received at the landfill.
     OPERATIONAL COST CONTROL. A primary duty
of administration is to monitor and control  the cost
of operation. Cost accounting isolates the  detailed
expenses  of ownership and  operation and  permits
comparison of costs against revenues. The impor-
tant costs of operation include: wages and salaries,
maintenance of and fuel  for equipment,  utilities,
depreciation  and interest  on buildings and equip-
ment, and overhead. Basic data  for cost accounting
include  the amount of waste disposed of at the fill,
either by  the  ton or cubic yard.  A cost accounting
system  recommended  for use at a sanitary landfill
has been developed  by  the Office  of  Solid Waste
Management Programs.2
     PERFORMANCE EVALUATION. In  most cases,
there is a control  agency at the State or  local level
that determines if the operation is being conducted
in a  manner that safeguards against environmental
pollution.  To  ensure a sanitary operation,  the ad-
ministrative agency should  conduct its  own per-
formance evaluation. This  should be done at the
administrative, not  the operating  or  supervisory
level,  and its requirements should  be at  least  as
stringent  as those  of the higher control  agency.
While operating and supervisory  personnel should
know  that these inspections will occur  at specified
frequencies, they  should not know the exact day.
This will help ensure a more representative inspec-
tion.
     PERSONNEL. To secure and retain competent
employees, the administration must have a  system-
atic  personnel management plan. First a  job de-
scription  should  be prepared for each position at
the sanitary landfill. A typical list  of positions for a
large  operation might  include:  (1)  administrative
tasks  (management, accounting, billing, engineer-
ing, typing, filing);  (2) operating tasks (weighing,
operating equipment—spreading, compacting,  ex-
cavating,  hauling, road  maintenance, dust control
                                                                                                   53

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—maintaining  equipment;   traffic  control,  vector
control, litter control, site security).*
     Once  the  job areas are defined,  management
must determine how many employees are needed;
there may be some overlapping responsibilities. For
instance, a  small  sanitary  landfill may need  only
one  operator to handle  all its  equipment. As the
size  of the operation increases, a division of labor
will become necessary for sustained efficiency.
     Governmental  operations normally will have a
civil  service system  that defines hiring and career-
advancement  procedures.   In this  case,  manage-
ment's responsibility is  to  write good job descrip-
tions and interview applicants. A potential employee
should understand the job fully before he is hired.
If  he is  expected to perform  other duties  during
emergencies, he should be fully apprised of this
fact. Management must  evaluate  the ability of po-
tential employees to comprehend and perform  their
tasks before they are hired.
     Private  operators may have more  latitude in
their employment practices. They  should also inter-
view and evaluate applicants as to interest in the job,
ability to do the work,  and potential for increased
responsibility.
     Once  an employee is  hired,  management  must
see that he is trained properly. Such training should
emphasize the  overall operation of the  landfill,  safe-
ty, and emergency procedures. Employees  responsi-
ble for more critical and complex tasks are given
more intensive  training. Employees should thorough-
ly  understand work  rules as well as procedures for
handing out reprimands  and submitting grievances.
     Wages must be comparable with similar em-
ployment  elsewhere.  Larger operations  may  in-
crease  employee  satisfaction  by  providing  lunch
room and locker facilities at the site. It is  desirable
to have on-the-job training, insurance plans,  pen-
sion plans, uniforms,  paid holidays and  vacation,
and  sick leave programs.
     PUBLIC RELATIONS. Public  relations is one of
the manager's  most important administrative  func-
tions. Solid waste disposal sites represent  an ex-
tremely emotional issue, particularly to those who
live in the vicinity of a proposed site. Many sites are
acceptable from an environmental  control aspect but
are  vigorously opposed  by citizens who  associate
them with old-fashion open or burning dumps. Con-
vincing the public of the advantages  of a sanitary
landfill  is  a tedious process  but can  be accom-
plished by explanation and education. The program
should begin early in the long-range planning stages
and  continue after operations begin. Public informa-
tion  should stress that at a  sanitary landfill  the
waste is covered daily, access  is restricted, insects
and  rodents  are  controlled, and  open  burning is
prohibited, Examples of properly operated sanitary
landfills  that have been accepted  near residential
areas should  be  pointed  out.  Benefits to be  de-
rived  by  using the completed site  as  a park or
playground, for example,  should  be emphasized.
The  media available to the solid  waste  manager
are not limited to radio, television, billboards,  and
newspapers,  but   include  collection  vehicles,  col-
lectors, disposal facilities, and  billing receipts. Help
provided by community organizations can do  much
to increase public support.  Extensive  "stumping"
by elected and appointed  officials  in support of a
proposed solid waste disposal  system is  invaluable
if the  speakers are knowledgeable and  have suffi-
cient aids to help them, such  as slides, films,  and
pamphlets.*
     The single most  important factor for winning
public  support of  a solid waste disposal system is
an elected or appointed  official who  firmly  believes
that it  is acceptable and needed. A  person willing to
accept the challenge of developing short- and long-
range plans and to see that they are properly  imple-
mented  is invaluable.  Once these  plans  are  devel-
oped and implemented, the disposal system must
be  operated  in a  manner that upholds  the  high
performance  of which  it is capable.
     A   comprehensive  solid  waste management
plan should be developed, preferably on  a  regional
basis.  Detailed design  and operating plans should
cover  a 10-year   period  and  long-range, land-use
planning should be developed  for  20 years. Appro-
priate  locations for sanitary landfill  sites can then
be  identified, based on the needs of the area to
be served. These sites  can be zoned for  waste  dis-
posal or other usage that will discourage develop-
ment of a residential area. The regional approach to
planning and implementation is especially desirable
because it often  is more  economically feasible for
all concerned. Land suitable for sanitary landfilling
is usually scarce or nonexistent within the jurisdic-
tion of  a  large city.  Smaller  communities nearby
may be  able to provide the land and thus be  able
to dispose of their own solid  wastes in an accept-
able manner.
     A key aspect of  public relations is  the  proce-
dure for handling citizen complaints. Deficiencies
in operating methods  or employee courtesy should
be investigated and acted  on promptly. If this prac-
      Depending on the scale of operation, certain of these
      tasks may be performed either on or off site.
    " Information pamphlets on the entire spectrum of solid
     waste management are available from the Office of Solid
     Waste Management Programs and in a series of guides
     issued by the National Association of Counties.
54

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tice is followed, citizens will be less  hostile toward    relatively  inexpensive step communities  can take
the operation, and employees will become more con-    to provide a  safe  and attractive environment.  By
scientious.                                           proper design, operation, and  management, sanitary
     A sanitary landfill  represents  a positive and    solid waste disposal can be provided.
                                            REFERENCES

              1.  National Solid  Wastes Management  Association  and Bureau  of  Solid Waste
                         Management. Sanitary landfill operation agreement and recommended
                         standards for sanitary landfill design and construction.  [Cincinnati],
                         U.S. Department of  Health,  Education, and Welfare, 1969. 44 p.
              2.  ZAUSNER, E. R.  An accounting system for sanitary landfill operations. Public
                         Health Service Publication No. 2007. Washington,  U.S.  Government
                         Printing Office, 1969. 18 p.
                                                                                                   55

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bibliography
Committee on Sanitary Engineering  Research, Solid  Waste Engineering Section.
            SED research report no.  21; sanitary landfill tests investigating refuse
            volume reduction and other phenomena. Journal of the Sanitary En-
            gineering Division, Proc., ASCE, 84(SA6):1853.1-1853.3,  Nov. 1958.
Committee on Sanitary Engineering  Research.  Survey of sanitary landfill prac-
            tices; thirtieth progress  report. Journal of the Sanitary Engineering
            Division, Proc., ASCE, 87(SA4):65-84), July 1961. Discussion. J. L.
            Vincenz, D. T. Mitchell, T. E. Winkler, and J. R. Snell. 88(SAl):43-49,
            Jan.  1962.  Reply.  Committee  on Sanitary  Engineering  Research.
            88(SA3):169-171, May 1962.
Committee on Sanitary  Landfill  Practice  of  the  Sanitary Engineering Division.
            Sanitary landfill.  ASCE—Manuals of Engineering  Practice No.  39.
            New York, American  Society of Civil Engineers, 1959.  61 p.
ANDEREGG, R. A.  Sanitary  landfill  proves financially best. American City, 73
            (7):159, 161, July 1958.
BAILEY, C. A., JR.  Public approves sanitary fill in a  residential zone "A" when
            the potential improvement to the land is apparent. American  City,
            67(11):126-127, Nov. 1952.
BASGALL, V. A., W. F. JOHNSON, and C.  F. SCHWALM.  Sanitary lill series—
            trench type: civic pride;  one man, one machine; do you realize that
            a  city's garbage  can turn  wasteland  into a  beautiful  playground?
            American City, 69(2):102-105, Feb. 1954.
BEVAN, R.  E.  Notes on the science and practice of controlled tipping of  refuse.
            London, The Institute of  Public Cleansing, 1967. 216  p.
BJORNSON, B. F., and M. D. BOGUE.   Keeping a sanitary landfill sanitary. Public
            Works, 92(9):112-114, Sept. 1961.
BLACK, R.  J.  Suggested landfill standards and methods.  Refuse  Removal Jour-
            nal, 4(10):10, 20-21, 25-29, Oct. 1961.
BLACK, R.  J.,  J. B. WHEELER, and W. G. HENDERSON.   Refuse  collection and
            disposal; an  annotated bibliography, 1962-1963. Public Health Service
            Publication  No.  91.  Washington,  U.S. Government Printing  Office,
            1966. 134 p. Suppl. F.
BOOTH,  E., and  E. CARLSON.  Rubber  tires  work  well  on  sanitary landfills.
            American City, 81(7):98-99, July 1966.
BOOTH,  E. J., and  D. KEAGY.   How to  operate  sanitary  landfill  in  really  cold
            weather. Public Works, 83(5):64-65, 102-103, May 1952.
California State  Water  Pollution  Control  Board.   Effects  of refuse  dumps on
            ground  water quality. Publication No. 24. Sacramento, 1961.  107 p.
[BLACK, R. J.]  Do you need a sanitary landfill? Public Health Service Publication
            No. 1012. Washington, U.S. Government  Printing Office, 1963. [8 p.]
ELIASSEN, R., F. N. O'HARA, and E. C. MONAHAN.  Sanitary landfill gas control;
            how Arlington,  Mass., discovered and corrected a danger spot in its
            sanitary landfill. American City, 72(12):115-117, Dec.  1957.
56

-------
FLEMING, R. R.   Solid-waste disposal. Part I—sanitary landfills. American City,
            81(1):101-104,  Jan.  1966.  Fundamentals of sanitary  landfill  opera-
            tion. Public Works, 95(12):88-89, Dec. 1964.

GOODROW, T. E.   Sanitary  landfill becomes major league training field.  Public
            Works, 96(8):124-126, Aug.  1965.

HENNIGAN,  R. D.   Sanitary landfill equipment  requirements. In  American Public
            Works Association Yearbook. Chicago, American  Public Works Asso-
            ciation, 1963. p. 327-332.

Institute  for Solid Wastes, American Public Works Association. Sanitary landfills.
            chap. 4. In Municipal refuse disposal. Chicago, Public Administration
            Service, 1970. p. 91-146.

JOHNSON, W. H., and B. F. BJORNSON.  The sanitary landfill; training guide.
            Atlanta, Communicable Disease Center,  1962. 20 p.

KLASSEN, C.  W.   Locating, designing  and operating sanitary  landfills.  Public
            Works, 81(ll):42-43, Nov. 1950.

KLASSEN, C. W.   Sanitary  fill standards.  American  City, 66(2):104-105,  Feb.
            1951.

MERZ, R. C., and R.  STONE.   Factors  controlling utilization of sanitary  landfill
            site;  final  report to  Department of Health, Education, and Welfare,
            May  1,  1960-May 31,  1963.  Los Angeles,  University of Southern
            California, 1963. 126 p.

MERZ, R. C., and  R. STONE.   Gas production in a sanitary landfill. Public  Works,
            95(2):84-87, 174-175, Feb. 1964.

MERZ, R. C. and  R. STONE.   Landfill settlement rates. Public Works,  93(9):103-
            106,  210, 212, Sept. 1962.

MICHAELS, A.  Municipal solid-waste disposal.  Part  II. The sanitary landfill. Amer-
            ican City, 77(3):92-94, Mar. 1962.

MOEHR,  L. H.  Park and playground built with  sanitary fill. American City, 65(4):
            102-103,  Apr.  1950.  Municipal  refuse  collection  and  disposal—
            evaluation, regulations,  methods,  procedures; a  guide for municipal
            officials. State of New York, Office for Local Government, 1964. 69 p.

NICKERSON, H. D.   Selection of sanitary landfill sites. San/talk, 9(2):9-12, Spring
            1961.

Operation of sanitary  landfills.   Public  Works, 89(9): 115-117,  206-209, Sept.
            1958.

PARTIN,  J. L.  Sanitary fill  practice in Los Angeles County. Journal of the Sani-
            tary Engineering Division, Proc., ASCE, 81(Separate 688):688.1-688.6,
            May  1955.

Refuse collection and  disposal—repairs and utilities; wartime technical manual.
            TM5-634. War Department,  Oct. 1945.

ROGUS,  C. A.  Use of completed sanitary landfill sites. Public Works,  91(1):139-
            140,  Jan. 1960.

Sanitary  fill—how it operates.  Part 1.  What it  is, and data on how it functions in
            cities with commendable fills. American City,  76(2):84-87, Feb. 1961.

Sanitary  fill—how it operates. Part II.   Basic  principles, economics, equipment
            and future use of reclaimed land. American City, 76(3):98-103, Mar.
            1961.

Sanitary  fill—how it operates.  Part III.   Basic methods and operating techniques.
            American City, 76(4):84-88, Apr. 1961.

SPENCER, C. C.  Recommended wartime refuse disposal practice; with particular
            reference  to sanitary landfill method  of disposal for mixed  refuse.
            Public  Health Reports, Suppl.  173. Washington, U.S.  Government
            Printing Office,  1943. 19 p. Reprinted as Refuse  disposal  by sanitary
            landfill method. Water & Sewage, 82(8):17-21, 48-50,  Aug. 1944.

University of California.   Analysis  of refuse collection and sanitary  landfill  dis-
            posal. Technical Bulletin No. 8. Sanitary Engineering  Research  Proj-
            ect. Richmond,  University of California, Dec. 1952. 133 p. (Series 37.)
                                                                                                       57

-------
VANDERVELD, J., JR.  Design and  operation of sanitary landfills. In American
           Public Works Association Yearbook.  Chicago, American  Public Works
           Association, 1964. p. 242-246.
VAN DERWERKER, R. J.  Sanitary landfill or incineration? American City, 66(3):
           98-99, Mar. 1951.
VAN DERWERKER, R. J.   Sanitary landfills in  northern  states;  a  report on the
           Mandan, North  Dakota  project.  Pub//c  Health  Reports,  67(3):242-
           248, Mar. 1952.
VAN KLEECK,  L. W.  Safety practices at sanitary landfills. Public  Works, 90(8):
           113, Aug. 1959.
WEAVER, L, and  D.  M. KEAGY.   Sanitary landfill method  of refuse  disposal  in
           northern states.  Public Health Service Publication No. 226. Washing-
           ton, U.S. Government Printing Office, 1952. 31 p.
WEAVER, L., and D. KEAGY.   Mandan, N.D., tries cold-weather operation  of sani-
           tary landfill. American City, 67(9):110-111, Sept. 1952.
WILLIAMS,  E. R., G. F.  MALLISON, and  P. P.  MAIER.   Light equipment for small
           town  sanitary landfill operations. Public  Works,  89(2):89-91,  Feb.
           1958.
WINKLER, T.  E.  Compaction, settlement of sanitary landfills.  Refuse  Removal
           Journal, l(12):8-9, 24-25, Dec. 1958.
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              ACKNOWLEDGMENTS
                   The Office of Solid Waste Management Programs gratefully acknowledges
               the many individuals who,  over the past three years, assisted in  developing
               the outline and  portions of the technical data contained in this  publication
               and those who graciously reviewed the numerous  drafts.
                   Members of the ad hoc panel  chaired by Mr. Ralph Black included: Donald
               Anderson, L. W.  Bremser,  Dale Garst, Eugene Glysson, Orville Meyer, John
               Parkhurst, Joseph Salvato, John  Vanderveld,  Jr., Jean Vincenz, and William
               Warner. U.S. Public Health Service officers John Wheeler and Charles Reid
               coordinated  the first year  efforts and assembled the initial data; the  latter
               also did much of the original work on finance and management.
                   Early drafts of this publication  were reviewed  by the  American Society
               of Civil Engineers;  the American Public Works  Association;  the American
               Public Health Association; the Consulting Engineers Council; the  National
               Solid Wastes Management  Association; the U.S.  Department of Health, Edu-
               cation, and Welfare's Bureau of Community Environmental  Management; the
               Soil  Conservation Service of the U.S.  Department of Agriculture; the Bureau
               of Land  Management  and  former Federal Water Quality Administration of
               the Department  of Interior; the Department of Defense;  and numerous State
               health agencies.
                                                                            pa  474
                                                                                                59

U. S. GOVERNMENT PRINTING OFFICE • 1972 O - 470-406

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