X-/EPA
                                  United States
                                  Environmental Protection
                                  Agency
                                  Municipal Environmental Research
                                  Laboratory
                                  Cincinnati OH 45268
                                  Research and Development
                                  EPA-600/S2-81-018  Mar. 1981
Project Summary
                                  Particle  Size Variation  Effects
                                  on  Landfilled  Solid  Waste:
                                  Cold  Climate Studies
                                  John V. Klingshirn
                                   An investigation was conducted to
                                  determine the effects of milled refuse
                                  particle size on landfilled solid waste.
                                  Four experimental test plots were
                                  constructed  using  four  different
                                  particle  size distributions. Each pit
                                  containing a specified  milled refuse
                                  particle  size was  evaluated in an
                                  attempt to correlate particle size with
                                  several variables: Wind displacement
                                  of  milled refuse,  differential
                                  settlement  of   compacted  milled
                                  refuse,  and attraction of vectors,
                                  rodents  , birds,  and wildlife to  the
                                  milled refuse.
                                   Data were collected over a period of
                                  20  months. Particle size distribution
                                  curves were developed for the milled
                                  refuse used. Four breakdowns "of the
                                  composition of the raw solid waste
                                  before  milling  were  included.
                                  Moisture content and  field density
                                  were determined, and  the variables
                                  correlated  with  particle size were
                                  studied.
                                   This Project Summary was devel-
                                  oped  by EPA's  Municipal Environ-
                                  mental  Research Laboratory,  Cin-
                                  cinnati, OH, to announce key findings
                                  of the research project that is  fully
                                  documented in a separate report of the
                                  same title (see Project Report ordering
                                  information at the back).

                                 Introduction
                                   To establish appropriate criteria  for
                                 design  and regulation of milled refuse
                                 disposal facilities,  detailed data were
                                 required  to correlate the effects of
                                  particle size  on operational and
                                  aesthetic variables.
                                   The purpose of this project was to
                                  evaluate the effects of particle size on
                                  the following variables:

                                   1. Wind  displacement  of  milled
                                      refuse.

                                   2. Differential settlement and
                                      deterioration of compacted milled
                                      refuse.

                                   3. Presence  of vectors,  rodents,
                                      birds, and wildlife at  a  milled
                                      refuse disposal site.


                                  Facility Design and
                                  Construction
                                   The site selected for excavation of
                                  four test cells was on a hillside in the
                                  vicinity of  the  City  of  Great Falls,
                                  Montana,  landfill. The site offered a
                                  wide,  unobstructed wind  path and
                                  proximity to the city-owned shredding
                                  facility.
                                   Following  excavation of the pits,
                                  plywood form walls were constructed
                                  inside to prevent collapse of the heavy
                                  native clay as it dried. Dimensions of
                                  each subsurface cell were 20 ft wide by
                                  35  ft long by 6 ft deep. Eight feet of
                                  undisturbed soil separated adjacent test
                                  cells.
                                   Municipal  refuse of  typical
                                  composition for waste collected in the
                                  autumn throughout the Great Fallsarea
                                  was hauled to the shredding facility. The

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solid waste shredding plant is equipped
with two Heil grinding mills with vertical
shafts and  capacities of  15  and 20
tons/hr.

  Since the primary objective of this
project  was  to  evaluate  various
parameters according to particle size, a
sieve  unit was designed and fabricated
to separate milled refuse  particle sizes
accurately. The sieve consisted of two
circular trommel units mounted on a
support frame. Each of the two cylindri-
cal units contained three different
screens.  Milled  refuse placed  in the
raised, open end tumbled down through
three  successively smaller  screens as
the trommel  was  turned  by hand.
Refuse  of  each  particle  size  was
collected  below  the  corresponding
sieves,  loaded into 65  yd3 transfer
trailers, and transported to the test site.
One  composite  sieve   sample  was
collected,  and  moisture  content  was
determine for each load.

  Hammermills  such   as  those
employed at the Great Falls facility wear
on  a   day-to-day basis,  resulting in
gradually  increasing  particle  size.
Special care was therefore  required to
ensure a reasonably consistent particle
size for the surface lift of each test cell
where wind displacement would occur.
  The  shredded refuse was spread in
lifts approximately  18 in. deep and
compacted to maintain an in-place wet
density averaging 1,000 Ib/yd3. A wide
range of particle sizes occurred in the
lower lifts of the test cells as a result of
hammer wear,  zthe sizes of  milled
refuse particles are given  as the screen
size through which 70%  of the refuse
passes. The  particle size  ranges in the
lowere lifts were as follows:

   Test cell:         inches

     No. 1	3Y4 to 4V2

     No. 2	2%to41/4

     No. 4	4   to 51/2

During placement of the refuse, test cell
No. 3 was  destroyed by  fire when
cinders were blown  from a fire at the
nearby landfill.
  After approximately 4 to 5 ft of refuse
had been placed, steel plates 2  ft in
diameter  were  installed to measure
settlement in the lower portions of the
test cells. The top lift on  each test cell
was  placed  over  the   plates  and
consisted of particles sized as follows
(70% passing screen sizes):

  Test cell    inches

    No. 1	21/2
    No. 2.
.41/2
    No. 4	6

On completion of the refuse placement,
holes were  drilled  back  down  to the
plate  surfaces,  and a 4-in.-diameter
pipe was installed above each to allow
for measuring settlement.
  Following  placement of the refuse,
fencing of Vz-in. galvanized mesh was
erected around  each  test cell.  A 3-ft
buffer  area was allowed  on the  sides,
and a 4-ft area was left on the ends of
each test cell to collect refuse displaced
by the wind. The U.S. Weather Bureau
Station at Great  Falls   recorded the
fastest observed 1 -min. sustained wind,
the precipitation, and  the temperature
data.  Displaced  refuse was  collected,
weighed,  and  recorded. To  permit
access to birds, no top  closure was
provided on the test cells. Observations
of bird activity at the site were made
while other  data were being collected.
Two small holes were cut  in the fencing
on opposite corners of  each test cell
area to allow access to ground animals.
Snap traps and box traps were placed to
record activity of mice and rodents in the
enclosed areas. A  Scudder grille was
employed to count fly  population.

Site Monitoring
  On  November   29,   1978,   when
construction  of the  test cells and
installation  of the  fencing had been
completed,  a  20-month monitoring
period began.  Shortly after monitoring
began, snow covered the test cells and
remained  until   mid-March.  The
extremely harsh winter (1978-1979)
had a detrimental effect on the variables
that were being monitored during this
time.  Heavy  snow cover and  frost
eliminated  any displacement  of the
refuse by the  wind.  Little settlement
appeared to be taking place within the
test cells because of the frozen ground
conditions. Except for the presence of
several mice,  no  bird,  fly,  or  rodent
activity occurred.
  Early  spring  brought  considerable
precipitation,  which also affected the
field  variables.  By mid-June,  it was
decided that if any wind displacement of
the refuse was to be observed,  action
should be taken to loosen the bondini
layer  that had  formed a crust on thi
surface. A rototiller was used to scarif
the surface  of the  test  cells. Thi
elevy'ion of the reference points on th(
surface of each test cell  was  thei
redetermined and again monitored fo
settlement.  Monitoring of  the othe
variables   continued   withou
interruption.
  Weed growth, a variable not originalh
monitored, was initially observed on th<
test cells  in May 1980. Weed  growth
continued throughout  the summer t<
the point where refuse displacement b\
wind was negligible. Most of the growth
occurred in test cell No. 1 and the leas
in test cell No. 4.
  Based  on   data   analysis   of  the
monitored variables,  it was  concludec
that the particle size of milled refuse
becomes important only if winds exceec
10 mph on a regular basis (the speec
reported by the U.S. Weather Bureai
Service as the fastest observed 1-min
sustained  wind). In such a case, largei
particles will be displaced in greatei
quantities than the  smaller  particles
Settlement and deterioration of millec
refuse compacted to a density of 1 ,OOC
Ib/yd3 does not proceed rapidly during
the initial 18  months. No  difference
appears to exist in  the settling and
deterioration  rates between  large and
small   refuse  particle sizes,  nor  does
there   appear  to be  any correlation
between particle size and the attraction
of flies,  mice, or birds.  The quick
formation  of  a surface bonding  layer
most likely accounts for the lack of wind
displacement,   vectors, rodents,  and
birds.  Compaction to achieve a relatively
high  density   may  account  for  the
absence of  rapid  deterioration  and
negligible  settlement  of  the  milled
refuse.
  The  full report, submitted  in fulfill-
ment of Grant No. R805012, by Thomas,
Dean  and Hoskins,  Inc.,  Great Falls,
Montana, under sponsorship of the U.S.
Environmental  Protection Agency, was
authored by L David Heckler.

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John V. Klingshirn was an Engineering Technician with the U.S. Environmental
  Protection Agency, Cincinnati, OH 45268.
Richard A. Carnes was the EPA Project Officer.
The complete report, entitled "Particle Size Variation Effects on Landfijjed Solid
  Waste: Cold Climate Studies," (Order No. PB 81-152 050; Cost: $6.50, subject
  change) will be available only from:
        National Technical Information Service
        5285 Port Royal Road
        Springfield, VA 22161
        Telephone:  703-487-4650
Stephen C. James is the EPA contact and can be reached at:
        Municipal Environmental Research Laboratory
        U.S.  Environmental Protection Agency
        Cincinnati, OH 45268
                                                                                    * U.aaOVBINilINTMWITINOOFnO«:1«»1-757-012/7024

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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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Fees Paid
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Protection
Agency
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