United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-190 August 1982
Project Summary
Environmental Impacts of
Special Types of Landfills
Deborah Grant Lord and William W. Beck, Jr.
Monitoring was done for 1 year at a
hillfill, balefill, millfill, strip mine land-
fill, and permitted sanitary landfill to
determine the impact of each on
water quality. Leachate generated by
the hillfill was strongest during initial
decomposition, but it was in the final
stages of anaerobic degradation dur-
ing the study period and therefore of
low strength. The presence of a shal-
low water table and groundwater
mounding within the hillfill resulted in
a severe, localized impact on ground-
water quality, but no impact on adja-
cent surface water. The balef ill method
channels water through the landfill
producing low strength leachate. This
low strength and the 30-meter separa-
tion distance between the landfill and
water table results in minimal impact
on groundwater quality. The millfill
generated the strongest leachate dur-
ing the study period because milling
accelerated the decomposition of
refuse. The millfill, however, had min-
imal, localized effect on groundwater
resources. The strip mine landfill gen-
erated leachate of moderate strength
and exerted a moderate impact on
ground- and surface-water resources.
The permitted sanitary landfill also
produced leachate of moderate strength
and exerted minimal, localized impact
on water quality because of the atten-
uative properties of the surficial
materials and a significant depth to
water.
This Project Summary was devel-
oped by EPA's Municipal Environ-
mental Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Solid waste generation and disposal
represent a continuing environmental
problem throughout the United States.
The amount of solid waste being dis-
posed of on land represents 90 percent
of the total municipal solid waste. This
solid waste is disposed in approximately
15,000 sites of which approximately
one-third are permitted facilities. The
Resource Conservation and Recovery
Act (RCRA) requires the phasingout of
open dumps during the 1980's, which
will result in disposing of increased
volumes of waste in existing sanitary
landfills and/or the opening of large
landfills.
Therefore, wherever suitable landfill
sites are available, they must be used
efficiently by placing more refuse in the
site (i.e., increasing its height, or hillfills)
or through volume reduction (i.e., mill-
ing or baling.) Large abandoned strip
mines offer potential for resolving
waste disposal problems in major met-
ropolitan areas. The growing need to
completely use available space at suit-
able waste disposal sites makes it
necessary to evaluate and compare the
standard sanitary landfill with alterna-
tive landfilling methods to determine
the relative environmental impact,
especially on ground- and surface-
water resources.
The alternative methods of waste dis-
posal (millfill, balefill, hillfill, and strip
mine landfill) represent potential pollu-
tion sources as does the standard sani-
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tary landfill. The characteristics of these
methods that may promote or prevent
pollution have not, however, been fully
documented. The purpose of this study
was to compare and evaluate volume
reduction (millfill and balefill) and alter-
native methods of waste disposal (hillfill
and strip mine landfill) with the sanitary
landfill to (1) determine the relative
environmental impact on water re-
sources, (2) determine site characteris-
tics that contribute to or, conversely,
prevent pollution, and (3) provide pro-
jections of the probable usefulness of
each method in a particular geographic
area.
Site selection was initiated with a
survey of known sites using alternative
methods of waste disposal (hillfill, bale-
fill, millfill, and coal strip mine landfill).
The survey identified 17 hillfills, 15
balefills, 23 millfills, and 253 coal strip
mine landfills east of the Mississippi
River.
Each site was evaluated on a selec-
tion criteria encompassing many varia-
bles (depth to water, geology, hydrology,
refuse-processing, site preparation).
Site selection criteria included:
1. Availability of detailed engineer-
ing and scientific reports.
2. Availability of background ana-
lytical data.
3. Existence of monitor wells.
4. Availability of the site for study.
5. Accessibility of the site.
6. Status of litigation, if any.
7. Overall representative nature of
the site.
8. The sites must be unlined.
9. Refuse must have reached field
capacity and be generating leach-
ate.
10. The sites must not accept large
quantities of industrial wastes.
11. All sites must have similar clima-
tology.
Survey data and site selection criteria
were compared and reduced to a matrix
that identified the principal characteris-
tics of each site as they relate to the
criteria and identified facilities appear-
ing to meet the criteria. The operator of
each site was contacted and a formal
request made for their cooperation in
conducting the study. To gain the coop-
eration of site owners, it was agreed
that site names and locations would be
held in confidence, so sites will be
referred to only by the method of land-
filling used and the general location.
Five sites were identified as principal
candidates for study. Their existing
hydrologic and analytical data were
reviewed to define the direction of
groundwater flow and contaminant
enclaves. This information was used to
determine whether additional monitor
wells were necessary to refine the capa-
bilities of the monitoring system that
would assess groundwater quality and
evaluate the environmental impact of
the waste disposal sites on the ground-
water quality. All sites except the sani-
tary landfill required additional wells.
Because of a previous study, the sani-
tary landfill had an.adequate network of
wells. Monitoring wells were located at
each of the other sites, upgradient and
downgradient of the landfills, to define
groundwater and contaminant move-
ment. Drilling methods were developed
for each site based on the prevailing
geologic conditions. Air rotary drilling
was used at the millfill and coal strip
mine landfill; soil boring was used at the
hillfill; and mud rotary drilling, at the
balefill.
To gain additional information on the
attenuation properties of each site, par-
ticle size analyses were conducted on
samples obtained during well drilling for
the four sites located on unconsolidated
material: the hillfill, balefill, millfill, and
permitted sanitary landfill. Samples
were tested according to the American
Society for Testing and Materials
(ASTM) D 422 to plot grain size distribu-
tion curves.
Chemical analytical parameters were
determined (by the U.S. Environmental
Protection Agency (EPA)) before the
study and were limited to three anions,
three cations, three nutrients, and three
demand tests. After studying the histor-
ical data for each site, it was determined
that each sample collected would be
analyzed for alkalinity, acidity, sulfate,
chlorides, total organic carbon (TOC),
chemical oxygen demand (COD), total
solids, total dissolved solids (TDS),
nitrate nitrogen, ammonia nitrogen,
phosphates, total Kjeldahl nitrogen
(TKN), copper, iron, manganese, sodium,
lead, and zinc. In addition, pH, tempera-
ture, and specific conductivity would be
measured in the field for each sampling
point.
Data from samples collected on a
quarterly basis for a year were exam-
ined tor seasonal fluctuations and to
determine if the results of chemical
analysis could be correlated with
meteorological events. At each site,
depth to water was first measured to
assess groundwater flow direction.
Then samples were collected after each
well had been cleared to ensure that
representative samples were obtained.
After samples were obtained and field
measurements of pH, temperature, and
specific conductivity taken, the samples
were filtered through No. 40 filter paper
using a Buchner filtering funnel and
flask. Samples were preserved accord-
ing to EPA standard methods, iced, and
shipped by air to the laboratory where
EPA standard analytical procedures
were followed.
The initial process of data interpreta-
tion involved reviewing historical (pre-
viously existing) analytical data for each
site selected.
Methods of display (series of bar
graphs (histograms). Stiff diagrams, and
a nitrogen index) were developed to
illustrate the results and to allow clear
concise interpretation and comparison.
Bar graphs illustrated the mean concen-
tration of the general indicators of water
quality including alkalinity, acidity, TDS,
TKN, COD, and TOC. The relative height
of each bar makes comparison among
the monitoring points readily apparent
for similar parameters.
To further illustrate effects on ground-
water and surface water and on water
quality variations, Stiff diagrams were
constructed using the average concen-
trations of sodium, iron, manganese,
zinc, chloride, sulfate, nitrate, and
phosphate.
The nitrogen index was used to delin-
eate redox (oxidation and reduction)
zones in groundwater and to determine
the location of reducing fronts as leach-
ate migrates from the landfill. Ratios for
the study period were calculated using
mean values.
On the basis of the environmental
impacts and the consideration of site
characteristics, waste disposal methods
were compared and contrasted to iden-
tify the suitability of each for use in var-
ious geographic areas.
Conclusions
Virtually all unlined solid waste dis-
posal facilities impact negatively on
ground- and surface-water resourcesto
some extent. The factors that effectively
mitigate the impacts of waste disposal
facilities include methods of operation,
site suitability (in particular, depth to
groundwater), and engineering design.
Based on the site selection process for
the present study, the conventional per-
mitted sanitary landfill is the most com-
mon method of waste disposal. The next
most common method is using strip
mine landfills, which are frequently
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found in Pennsylvania, Ohio, and Illi-
nois. Millfills, balefills, and hillfills are
relatively uncommon.
The landfills investigated in this study
performed fairly well and exerted only
minimal, localized adverse impacts on
the surrounding groundwater and sur-
face water; an exception is the hillfill. In
general, contamination from each site
was not significant beyond the property
boundary. The effects of each landfill on
groundwater quality could be compared
with that of the background ground-
water quality, but downgradient water
quality was frequently within drinking
water standards. Many differences
observed in the study resulted from the
method of landfilling and variations
among site conditions, ages, and the
amount of refuse emplaced in each land
fill (Tables 1 and 2). The potential volume
and strength of leachate were two pri-
mary factors that are direct functions of
the method of landfilling.
The following are conclusions regard-
ing each of the five methods of opera-
tions investigated.
Hillfill
Hillfilling is an effective method to
reduce the areal extent of a landfill. It
increases the volume of waste per unit
area through an increase in height and
decreases the potential volume of
leachate because of steep slopes that
reduce infiltration. Its relatively small
base lends itself well to a leachate
collection system. Since the hillfill that
was studied was large, however, it had
the greatest total potential volume of
leachate. The leachate generated by the
hillfill (1969 data) was the strongest.
During 1978 and 1979, the hillfill was
in the final stages of anaerobic degrada-
tion, however, and therefore generated
a leachate of lower strength at that time.
A hillfill may be less structurally stable
than a permitted sanitary landfill and
leachate breakouts between lifts and
cells may occur. Gas production also
may be a problem. In addition, the steep
slopes increase runoff that contributes
to erosion and causes maintenance
problems.
The hillfill had the most severe
environmental impact on groundwater
resources but no impact on adjacent
surface water Its impact was localized
because of a minimal groundwater
gradient and attenuation attributable to
the presence of clay at the site.
Leachate did not contaminate the
bedrock aquifer but moved downward
into the shallow aquifer. Degradation of
the groundwater resources was pri-
marily caused by the shallow depth to
water and the groundwater mounding
occurring within the hill. Leachate is
impounded within the hill as a result of
the construction of a relatively im-
permeable clay base. Because of the
head of leachate within the hillfill, it is
possible that leachate migrates outward
from the base of the landfill through
ruptures in the clay.
Balefill
Baling is the most effective method of
volume reduction; it results in the
highest density of refuse, void space is
reduced, and structural stability is
increased. It effectively reduces the
area required for landfilling and mini-
mizes the amount of cover material
required. Among the five sites investi-
gated, the balef ill contained the greatest
total weight of refuse and the greatest
density of refuse. Although the balefill
should have the lowest potential
volume of leachate per unit basal area
because of its large basal area, it has the
second highest total potential leachate
volume.
Less equipment is needed at the site,
and it is more easily maintained; only a
forklift and small front-end loader are
necessary. In addition, if the baling
facility is centrally located for col lection
trucks, there will be less driving time
and fuel consumption. Resource re-
covery is facilitated at the baling plant;
as refuse travels along conveyor belts,
metals and corrugated cardboard are
easily removed for recycling.
The disadvantages of baling refuse
include equipment costs, which may be
partially offset by the economic ad-
vantages previously discussed. Care-
less operation and stacking at the
balefill site may forfeit much of the
benefit of volume reduction. Finally, if
refuse bales are placed near water or in
an area where groundwater may reach
them during wet periods, there will be
considerable pollution potential.
The leachate generated had the
lowest concentration of any among the
five landfills studied, and this was
attributable to the high density of refuse
that causes a rapid channeling of water
through the bales. The site has had a
minimal, localized impact on ground-
water resources, indicating a lower
level of contamination when compared
with that of the permitted sanitary
landfill. The minimal impact can be
attributed to a combination of low
strength leachate and a separation
distance in excess of 30 m (100 ft)
between the base of the landfill and the
water table.
Millfill
Millfilling achieves a high density of
refuse and is an effective volume
reduction method that minimizes the
area required for landfilling and,
although such was not th.e practice at
the site studied, does not require daily
cover. It is structurally more stable and
has less settlement than a permitted
sanitary landfill because of its relative
density. The increased volume of refuse
within a smaller area and the rapid
decomposition producing higher con-
centrations of leachate facilitate leach-
ate collection and treatment. This
method can be advantageous because
proper site selection and a substantial
separation between the millfill and the
groundwater result in rapid decomposi-
tion and a shorter time period needed
for stabilization with the landfill.
The public is generally more receptive
to a millfill site bacause blowing papers,
vectors, and odors are reduced. Less
cover material is needed, and there^are
more efficient transport and landfilling
procedures.
A major disadvantage of this method
is the cost of running a milling facility. In
addition, if not properly separated from
groundwater, or surface water, or both,
the strong leachate produced could
have a severe effect on the environment.
The leachate generated by the millfill,
based on the one sample that could be
collected, was the strongest among the
leachates analyzed during the study
period. The increased surface area of
milled refuse accelerates physical and
chemical decomposition; leachate is
produced more quickly and is charac-
teristically of greater strength. The
leachate is comparable to the initial
leachate concentration generated by
the hillfill. It has had a minimal localized
effect on groundwater resources and
comparably less impact that the per-
mitted sanitary landfill which, in part,
may be because of the distance be-
tween the fill and the monitor wells. The
millfill has not significantly polluted the
aquifer, and the water supply at the
landfill remains potable. Because daily
cover is applied, the millfill examined in
this study appears to behave more
similarly to a permitted sanitary landfill
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Table 1. Characteristics Contributing to the Impact of Each Landfill on Ground and Surface Water
Landfill
Hillfill
Balefill
Millfill
Strip mine
landfill
Permitted
sanitary
landfill
Years since
completion
8
(operated
from
1965-71)
5
(operated
from
1971-74)
Active
(since
Dec. 1973)
Active
(since
June 1971)
4
(operated
from
1971-75)
Area of
fill
16 ha
(40 ac)
4 ha
(9ac)
12 ha
(30 A)
7 ha
(18 ac)
5.7 ha
(14 ac)
4 ha
(10 ac)
Total weight
of refuse
272,340 tonnes'
(300,000 tons)
337,800 tonnes
(372, 155 tons)
317,700 tonnes
(350.000 tons)
105,000 tonnes
(11 6,000 tons)
38,800 tonnes
(42,750 tons)
Average volume
per unit area
47,500 m3/ha
(25,000 ycP/ac)
250,000 m3/ha
(130,000 yd3/ac)
127,840 m3/ha
(64,800 ycP/ac)
69,957 rri>/ha
(37.027 yd3/ac)
25. 155 m3/ha
(13.1 04 yd3/ ac)
Approximate
density
of refuse
355 kg/m3 a
(600 Ibs/yd3)
800 kg/m3
(1.350 Ibs/yd3)
653 kg/m3
(1. 100 Ibs/yd3)
263 kg/m3
(450 Ibs/yd3)
386 kg/m3
(652 Ibs/yd3)
Method of
operation and
cover-to-refuse
ratio
Above-grade
landfill refuse
cells.
1:1
Baled refuse.
stacked.
1:9
Covered, milled;
• area filled.
1:7
Refuse filled
in strip mine
excavation.
1:4
Trench method.
1:1
a Estimated value. ,
b Chemical interference suspected.
c Chemical interference.
d Boone County test cell 2D - mean value of analyses from 4 years following completion of cell.
e No historical data is available for the millfill, the strip mine landfill, or the permitted sanitary landfill.
Table 2. Impact of Five Sites Shown by Representative Downgradient Wells
Parameter a
alkalinity
TOC
COD
TDS
TKN
Na
DTW'
distance0
Avg% clay
PVL*
Hillfill b
589
22.4
52.0
922
2.04
12.1
899
52.0
131.8
1360
5.14
115.1
0
Balefill c
370
33.6
71.5
424
0.25
24.3
35(115)
42.7(140)
27,057
4%
(21.93)
0
3%
20,032 (16.02)
Millfill c
334
9.4
8.7
396
0.14
7.78
6. 1 (20)
133.2 (437)
4%
15,232 (12.86)
Strip
mine
landfill "
min max
243
6.8
11.7
623
0.28
6.5
24
318
8.8
17.3
817
1.60
50.0
.4 (80)
Permitted
sanitary
landfill e
min max
279
5.9
0.55
455
0.14
5.9
42. 1 (138)
13,059
—
(10.52)
581
10.1
14.3
607
0.37
66.7
15.2 (50)
0
9%
7,072 (5.80)
* Chemical analyses expressed in mg/L
b Downgradient wells, MP #4, #5, #3, and #10 showing minimum and maximum values.
c Downgradient well, MP #2.
d Downgradient wells, MP #5 and #7 showing minimum and maximum values.
e Downgradient wells, MP #2 and #5 showing minimum and maximum values.
' Depth to water below landfill base in m (ft).
9 Approximate distance between landfill and well(s) in m (ft).
h Potential volume of leachate in m3 (ac-ft).
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Sediment type
underlying landfill
rom surface to bedrock)
and average % clay
1 sorted sands & gravels,
n (40 ft). Poorly sorted
12 m (40 ft). 4%
dy till, 15 m (50 ft).
•ial drift (clay, sand,
el). 9-37 m (30-1 20 ft).
Average annual
precipitation
Depth to water + deviation
from base of during
landfill study period
Mounded in 86.49
hillfill +27.23
35. 1 m (1 15 ft) 65.88
+ 9.74
cm (34.05
cm (10. 72
cm (25.94
cm ( 3.84
in)
in)
in)
in)
Strength of
Potential
volume
of leachate
27,057 m3
(21.93 ac-ft)
20,032 m3
(16.02 ac-ft)
1978-79
study in
mg/L
COD
TDS
Na
SO*
COD
TDS
Na
2,992
3,084
380
12,000
967
3,801
572
Leachate6
historical
data in
mg/L
(39,680)
(19.144)
( 900)
( 680)
( 718)
( 2.241)
( 1.079)
vial sands & gravels,
m (328 ft). 3%
2.040
•ial outwash (sands &
els), 15 m (50 ft).
4%
ey decomposed spoil.
5 m (5-1 6 ft).
5m (16 ft). 9%
6.1 m( 20 ft) 83.69 cm (32.95 in)
+ 0.06 cm ( 0.02 in)
24.4 m ( 80 ft) 104.10 cm (40.98 in)
+ 6.92 cm ( 2.71 in)
15.2 m ( 50 ft) 78.60 cm (30.94 in)
+ 4.94 cm ( 1.94 in)
15,232 m3
(12.86 ac-ft)
13,059 m3
(10.52 ac-ft)
7.072 m3
(5.80 ac-ft)
COD
TDS
Na
S04
COD
TDS
Na
S04
COD
SC
Na
SO4
23,650
19,500
828
519
9.580
11,145
1,500
b
17,799C
8,320C
281C
171C
than to the classic millfill, which is
uncovered.
Strip Mine Landfill
The strip mine landfill had the lowest
refuse density of the five sites investi-
gated. Because of the existing strip pits,
previously excavated cover material
(spoil), and existing access roads,
however, a strip mine landfill can be
operated at a relatively lower cost than a
permitted sanitary landfill or either
method of volume reduction landfilling.
Land reclamation being simultaneously
accomplished is an additional benefit.
Another possible advantage might be
the presence of established rail service
to major cities that would facilitate the
long-range transport of wastes from
metropolitan areas.
Excavation creates substantial high-
walls in many strip mines so that the
volume of refuse per area may be
increased in comparison with that at a
permitted sanitary landfill. Steep slopes
may minimize infiltration and therefore
decrease the potential volume of
leachate generated. The leachate tends
to neutralize acidity from acid mine
drainage. Underclays that often are
present beneath coal limit leachate
migration.
Disadvantages of strip mine land-
filling include the absence of significant
soil thickness for the attenuation of
leachate; this increases the pollution
potential of the landfill. The complex
hydrogeologic conditions associated
with coal mining frequently increase
the potential for contamination. Ex-
amples are the presence of perched
water tables, underclays, and imperme-
able shales as well as a potential forthe
channeling of contamination through
fractures and bedding planes. The steep
slopes often found at strip mine landfills
may promote erosion and maintenance
problems not found at permitted sani-
tary landfills, balefills, or millfills.
A strip mine landfill would be subject
to blowing paper, vectors, and odor
problems similar to those of the conven-
tional type landfill. Because of the
remoteness of most strip mining areas,
however, less public reaction may be
anticipated, but the transportation of
refuse from the place of generation to
the landfill site may involve greater
distances than at other types of landfills.
The leachate generated was of
moderate strength and lower in' con-
centration than that initially generated
by the hillfill or millfill. The leachate
exerted a .moderate impact on ground-
water and surface water resources.
Because attenuative soils generally are
not present, there is the greatest
potential for contamination. The site,
however, did not have a significantly
adverse impact on the groundwater
because: (1) a substantial separation
exists between the base of the landfill
and the water table; (2) the base of the
landfill was backfilled with spoil mate-
rial before initiating landfilling opera-
tions; and (3) the slopes increase the
amount of runoff and decrease infiltra-
tion because the completed areas of the
landfill have been restored to approxi-
mate original contour.
Permitted Sanitary Landfill
Permitted 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.
The planning and applying of sound
engineering principles and construction
techniques make the sanitary landfill an
acceptable alternative to open or
burning dumps.
The primary advantage of a permitted
sanitary landfill is the relatively low
operation cost. Disadvantages include
the large area required for landfilling
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and the cost of suitable land. Subsidence
limits the possible subsequent uses of
the land. In addition, vectors, blowing
paper, and odors are problems common
to this method of landfilling and often
incur negative public reactions.
Among the sites investigated, the
permitted sanitary landfill had the least
amount of refuse and the lowest
potential volume of leachate due to its
small areal extent. It exerted a minimal
localized impact on the surface and
groundwater resources in its vicinity.
Immediately beneath and adjacent to
the landfill, degradation of groundwater
was noticeable; however, there was no
contamination to adjacent surface
water. The minimal impact of the
permitted sanitary landfill leachate on
groundwater may be attributed to a
combination of the attenuative proper-
ties of the surficial materials at the site
and a significant depth to water.
When projecting the applicability of
the methods of landfilling discussed in
this report, a primary consideration is
the potential contamination of surface
and ground waters. Among the factors
that must be considered when siting
landfills, climate is the most important
since it determines the amount of
recharge to an area. The amount of
recharge is also affected by topography
and vegetation.
The geology, soils, and topography of
a region determine the capacity of the
natural surroundings of a landfill site to
accept and attenuate pollutants. The
type of bedrock (and/or surficial geologic
deposits) beneath a landfill are of basic
importance because they determine the
characteristic soils and topography of
an area. Geology also influences
groundwater movement. Depending on
the type of bedrock and the climate,
physical and chemical weathering
processes produce varying conditions
such as shallow depth to bedrock
(shallow soils), thick saprolite, and
problems such as sinkholes in lime-
stone terrain.
Desirable conditions for a landfill site,
because they promote attenuation,
include the presence of thick saprolite,
thick deposits of glacial till, other glacial
sediments containing clay, and other
unconsolidated sediments containing
significant amounts of clay. The
presence of 'sand or gravel and the
absence of soil or unconsolidated sedi-
ment are undesirable conditions.
The characteristics of the ground-
water in an area is a primary concern. A
substantial distance between the base
of a landfill and the top of the water table
is imperative. All types of landfills have
a great potential for the severe con-
tamination of groundwater resources if
they are located above the apparent
level of the water table. Seasonal
variations and the tendency for mound-
ing of groundwater within landfills must
be considered. The natural qualityof the
groundwater should also be considered.
If it has already been degraded by
geologic conditions (e.g., acid mine
drainage) or if the groundwater is saline
as in coastal areas, a landfill will have a
relatively diminished impact since such
groundwater cannot be considered for
use without treatment.
Finally, the population of an area
should be considered; density deter-
mines the amount of refuse produced
and the rate at which it is produced and
affects the availability and cost of useful
land. Considerations of population may
affect the preference for using volume
reduction compared with using conven-
tional methods of landfilling.
The combination of the factors pre-
sented above makes certain methods
of landfilling more desirable in particu-
lar geographic areas of the country or
where certain socioeconomic condi-
tions prevail.
Recommendations
Hillfills are particularly suitable for
densely populated areas since the
volume of refuse per acre is reduced.
Since the potential volume of leachate
isalsoreduced, hillfillsmaybe preferred
over other methods of landfilling in
humid regions; care must be taken,
however, to avoid areas with a shallow
depth to groundwater.
Balefilling is also a preferred method
for densely populated regions because it
too is a method of volume- reduction.
Because a balefill produces leachate of
low strength and has a relatively low
potential for contamination, balefilling
might be the best method of landfilling
for the humid south, especially in areas
with a shallow depth to water, and in
sandy coastal areas with relatively little
potential forattenuation. The benefits of
balefilling generally are not applicable
to arid regions because such areas are
usually-less populated and because the
potential volume of leachate in such
regions would be small for any type of
landfill.
Because it produces a strong leachate,
millfills would be best located in areas
having thick deposits of unconsolidated
sediments containing significant
amounts of clays. The glaciated north-
east, the Great Lakes region, and the
Piedmont province in both the northeast
and the humid south are examples of
areas suitable for millfills. They charac-
teristically have geologic materials that
can attenuate the relatively strong and
rapidly produced leachate of a millfill,
provided there is a substantial depth to
water beneath the landfill. Millfilling
reduces the volume of refuse and the
size of the area needed for landfilling;
these considerations are advantageous
in the densely populated eastern
portions of the country.
Strip mine landfills are limited to
areas of the country that have been strip
mined. Those located in the arid west
have the benefit of a climate that tends
to limit the potential volume of leachate.
Strip mine landfills are advantageous
primarily because strip mining areasare
sparsely populated and the previous site
development for mining offers certain
economic benefits.
The conventional method of land-
filling solid waste is applicable through-
out the country, but particularly in
sparsely populated arid areas where
landfilling by the trench method would
offer the advantage of relatively low
cost. The conventional method of
landfilling is also desirable in glaciated
regions and in older eroded mountainous
regions where saprolite is found. The
permitted sanitary landfill (trench
method) is not recommended for the
humid south or coastal plain regions
because of the shallow depth to water
typical of such areas. Excavations for
trenches decrease the distance to the
water table and thus increase the
pollution potential of the landfill.
Based on the environmental impacts
of each of the five sites studied, it
appears that all five methods are envi-
ronmentally acceptable methods of
operation if site characteristics allowfor
the natural renovation of leachate. It
must be emphasized that site character-
istics, particularly depth to water, are
crucial to the ultimate impact of any
landfill, regardless of the method of
operation. The results of this study
suggest that balefilling and millfilling
offer significant benefits when these
methods are used under optimal site
specific circumstances. Because of
their capital cost, however, a relatively
dense level of population is required to
support the associated processing
facilities.
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The full report was submitted in ful-
fillment of Contract No. 68-03-2620 by
SMC-MARTIN under sponsorship of the
U.S. Environmental Protection Agency.
Deborah Grant Lord and William W. Beck, Jr., are with SMC-MARTIN, King of
Prussia, PA 19406.
Donald E. Banning is the EPA Project Officer (see below}.
The complete report, entitled "Environmental Impacts of Special Types of
Landfills, "(Order No. PB82-231432; Cost: $22.50, subjectto change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati. OH 45268
OUSGPO: 1982 — 559-092/0446
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