-8
United States
Environmental Protection
Agency
Municipal Environmental
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-155 Nov. 1984
Project Summary
Sewage Sludge Versus
Commercial Methods for
Reclaiming Strip-Mine Soils
Lilia A. Abron-Robinson and Leon W. Weinberger
Two types of methods for reveget-
ating strip-mined soils were compared
with regard to cost, feasibility, and
environmental impacts: the use of
municipal sewage sludge and commer-
cial methods.
The in-depth investigation included
visits to strip-mined sites being reclaimed
with sewage sludge and a literature
review to gather data on strip-mined
land reclaimed with commercial meth-
ods. The literature review was neces-
sary because adequate data were not
available otherwise.
Cost comparisons of the two reclama-
tion methods were made using only
those costs associated with renovation
after the sludge or commercial materials
were delivered to the site. This compari-
son indicated that reclamation of strip-
mined land with sewage sludge costs
roughly the same as commercial meth-
ods.
The study also used available data to
show that both commercial methods
and sewage sludge application could
be used successfully to reclaim strip-
mined soils with no adverse environ-
mental impacts. Selection of the re-
clamation practice should be based on
site-specific evaluations of cost, social.
political, and aesthetic factors.
This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory, Cincinnati, Ohio,
to announce key findings of the research
project that is fulfy documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The process for the surface mining of
coal, called strip mining, is accomplished
with either area or contour stripping. Both
practices involve the removal of over-
burden materials to expose the coal, the
removal of the coal, and the replace-
ment of overburden into the excavated
pits. Strip-mining operations typically
leave behind steeply sloping spoil or
waste mounds depleted of plant nutrients
and organic matter. These mounds
rarely support vegetation and are easily
eroded, causing contamination of near-
by water supplies and the destruction of
wildlife habitat. These mounds prevent
rapid, productive redevelopment of strip-
mined lands.
The Surface Mining Control and Rec-
lamation Act of 1977 (PL-95-87) was
passed by the Federal government in
response to citizen concern and the
negative environmental impacts of the
waste mounds. Section 508 of the Act
sets forth the general requirements for
reclamation plans submitted as part of
application permits. The main objective
of reclamation is to restore the ability of
the residual spoils to support a vegetative
cover.
Reclamation. with commercial meth-
ods relies on products readily available
on the open market. Inorganic fertilizers
are used in combination with lime and
topsoil to restore the fertility of strip-
mined lands.
Reclamation with municipal sewage
sludge uses the residue remaining after
the treatment of wastewater. Sewage
sludge contains essential plant nutrients,
organic matter, and a high alkalinity
that can neutralize acid soils. The dis-
posal of sewage sludge has been a
problem for many municipalities, and
using it for reclamation provides a
beneficial alternative to sludge disposal.
Sewage sludge also contains various
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trace elements (such as metals) that
could cause environmental problems,
depending on the quality of the sludge.
Thus environmental monitoring programs
are required by Federal and usually State
regulatory agencies to document en-
vironmental changes at sludge applica-
tion sites.
This study was undertaken to compare
the costs, feasibility, and environmental
impacts of both types of strip-mined
reclamation methods (commercial and
municipal sewage sludge). The investi-
gation included visits to strip-mined sites
being reclaimed with sewage sludge
and a literature review to gather data on
strip-mined land reclaimed using com-
mercial methods. The review was neces-
sary because adequate data were not
available otherwise.
Reclamation Sites
Fulton County, Illinois
At the Fulton County site, sewage
sludge is being applied to about 480 ha
(1,200 acres). The sludge disposal
operation has continued since 1971,
with certain fields receiving the maximum
annual sludge application of 576 metric
tons/ha. Successful reclamation has
been achieved, and both soil organic
levels and fertility have increased.
Growing a corn crop each year and
selling it to a local animal feedlot results
in a financial return.
Extensive environmental monitoring at
the site does not indicate any significant
adverse impacts on surface water or
groundwater. Although cadmium con-
centrations have increased in the corn,
they are within Federal limits for animal
feed.
Costs for the Fulton County operation
are primarily influenced by transportation
and land costs. The distance from the
sludge generation point to the disposal
site incurs transportation costs that are
nearly half of the total cost. The entire site
includes 6,100 ha (15,250 acres) located
outside the jurisdiction of the municipal
agency producing the sewage sludge.
The land costs and real estate taxes
would not usually be incurred if a
municipality used sludge to reclaim land
in its own jurisdiction. The Fulton County
operation has permanently solved a
sludge disposal problem, reclaimed
strip-mined land, and been positively
received by the public.
Ottawa, Illinois
The State of Illinois requires that about
0.8 ha (2 acres) of a 60.7-ha (150-acre)
strip-mined site be reclaimed to demon-
strate the effectiveness of using sewage
sludge before the remaining area is
subsequently reclaimed. Digested lagoon
sludge was applied to the area, and
grass was sown in late 1979. The pilot
project successfully reclaimed the site by
producing a flourishing grass cover.
Environmental monitoring did not
indicate any adverse impact on ground-
water or surface water. Costs for the
project were greatly influenced by the
sludge transportation distance, which
represented more than 64 percent of the
total costs for reclaiming the 0.8-ha (2-
acre) site.
The Ottawa operation provides a
viable sludge disposal operation. Though
no large volume of sludge has been
used to date, the project demonstrates
the usefulness of sludge in reclaiming
strip-mined sites. Overall, the Ottawa
operation has had positive public reac-
tions, with no negative reaction of any
kind. In fact, it may influence other private
concerns to enter into similar ventures.
Sites Using Commercial
Methods
A literature review was conducted to
gather data on strip-mined land that
had been reclaimed using commercial
methods. The review indicated that
although commercial methods can be
successful for reclamation, the vegetation
may not survive on very acid soils if the
underlying acids migrate upward to the
root zone. On very acid spoils, the depth
of the topsoil should be increased, and
limestone should be applied before the
topsoil is added. In all cases, periodic
fertilization and liming are needed to
maintain a good vegetative ground
cover.
The data also indicated that the water
quality of acidic mine spoil runoff is
rapidly upgraded after the spoil is
covered with topsoil. The duration of this
improvement depends on the stability of
the topsoil and the growth of the plant
cover. Groundwater quality has shown a
short-term reduction in acidity and
sulfate concentration following mine
spoil reclamation.
Cost Analysis
The full report presents only cost data
for sites where the costs were actually
incurred and documented. The data
were developed using two scenarios: (1)
an acid strip-mined site with relatively
steep slopes reclaimed to produce a
forage crop similar to the Ottawa opera-
tion, and (2) a neutral-pH soil withtlatter
slopes reclaimed to support row crop
agriculture similar to the Fulton County
operation. Cost estimates were developed
for each scenario with a range for unit
and total costs. Earthworking generally
incurred the greatest unit cost.
Cost comparisons for reclaiming strip
mines using sludge and commercial
methods are difficult to make because
of the dissimilarities of the two methods
and the differences in the cost data
bases available.
For purposes of comparison, costs for
reclaiming with sludge included only
those costs associated with the operation
after the sludge was delivered (monitor-
ing, staff, sludge application, site prepar-
ation, and farming costs). Therefore, the
total unit costs used for comparison with
commercial methods for the Fulton
County and Ottawa operations were
$9,045/ha (S3,660/acre) and $26,8047
ha ($ 10,850/acre), respectively. The unit
costs for commercially reclaiming the
two sites ranged from $8,382/ha ($3,3957
acre) to $15,543/ha ($6,290/acre) and
from $7,243/ha ($2,930/acre) to $13,5687
ha ($5,495/acre), respectively. These
costs do not take into consideration the
degree of reclamation achieved at any
of the sites studied or described. The rate
of sludge application that would be
required to be equivalent to commercial
methods of reclamation is not clear, so a
range of reclamation costs was calcu-
lated to achieve the various reclamation
objectives described as follows.
The main objective of the Fulton
County operation was to build up organic
matter since the soil pH was neutral.
Costs were estimated for achieving 1, 2,
and 3 percent soil organic matter, which
corresponds to a sludge application rate
of 100, 200 and 300 metric tons/ha,
respectively. The costs ranged from
$13,546/ha ($5,485/acre) to $40,6387
ha ($16.450/acre). The objective of
reclamation at the Ottawa site was to
neutralize the acid soils and promote
grass growth. Costs were estimated for
sludge application rates ranging from
1,000 to 2,500 metric tons/ha, and they
ranged from $10,860/ha ($4,400/acre)
to $27,150/ha ($11,000/acre).
Reclamation costs for commercial
methods were estimated for each scenario.
Estimates were made for costs of topsoil
replacement ranging from 30 to 122 cm
deep. The estimates ranged from $8,3827
ha ($3,395/acre) to $29,8087 ha ($12,0707 ^
acre) for site 1, and from $7,243/ha I
($2,935/acre) to $27,833/ha ($ 11,2707
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acre) for site 2. Municipal sludge applica-
tion for strip-mined reclamation was
shown to be roughly equal in cost to
commercial reclamation methods. A one-
time sludge application (Ottawa) appeared
to be less costly and more comparable to
commercial methods.
Social and Environmental
Impacts
Selection of a sludge management
strategy cannot be based solely on cost.
Land reclamation using sewage sludge
offers the municipal agency a productive
use for a waste product. The public
usually reacts positively to using sludge
for reclamation, as this practice tends to
be more aesthetically acceptable than
a landfill or an incinerator complex.
Residents near the reclamation site
may oppose the transportation of sludge
outside the jurisdiction of the sludge-
generating municipal agency. The public
may also be concerned with the potential
for environmental degradation posed by
the presence of many trace elements in
the sludge.
Private companies may chose to
reclaim their strip-mined lands using
sewage sludge to improve public rela-
tions, or they may avoid it because of
public concern. Additionally, these
companies are notgenerallyfamiliar with
the concept of reclamation using sewage
sludge. They may riot have the proper
equipment for applying sludge and may
also be hesitant about becoming involved
with the requirements and red tape of
municipal agencies.
Conclusions
The results of the environmental
monitoring at the Ottawa and Fulton
County sludge reclamation sites indicate
that municipal sewage sludge does not
adversely affect groundwater, surface
water, soil, or crops when properly
managed. The data from these two sites
show that the use of sewage sludge for
strip-mined reclamation is a highly
satisfactory procedure, since sludge
restores the neutral pH of acid soils and
increases the nutrient and organic
matter content. The Fulton County site is
now producing corn, and the Ottawa
site supports a vigorous stand of grass.
The literature survey revealed that
commercial methods would not nega-
tively affect groundwater, surface water,
soil, or crops if properly managed. But
commercial methods may have a short-
lived effect, since there appears to be a
tendency for the underlying acids to
migrate upward to the root zone even-
tually and affect the growing plants.
Sewage sludge may thus have a more
permanent effect on keeping a good
vegetative cover on renovated, strip-
mined land. This tendency may make
the sewage sludge renovation of strip-
mined land attractive, even if it is more
costly.
Recommendations
1. Factors that should be considered
when selecting sewage sludge or
commercial methods for reclaiming
strip-mined lands include the owner-
ship of the site, the availability of
sewage sludge, the sludge trans-
portation distance, and the pros-
pects for short- or long-term disposal.
2. The cost comparison procedure will
vary depending on who is making
the comparison—the strip-mine
owner or the sludge generator. An
owner should compare the costs of
both practices based on site-specific
information, whereas a sludge
generator should compare the cost
of land reclamation with that for
other viable sludge management
options.
3. Insofar as possible, cost comparisons
for sewage sludge and commercial
methods should be made for achiev-
ing the same end conditions.
4. Many studies have been conducted
to demonstrate that sewage sludge
can be used to renovate strip-
mined land. Thus attention should
now be paid to improving opera-
tions (such as methods of applica-
tion, transportation, etc.) and to
defining more clearly the level of
renovation achieved by various
sludge application rates.
The full report was submitted in partial
fulfillment of Contract No. 68-03-3018 by
PEER Consultants, Inc., Rockville, Maryland
20852, under the sponsorship of the U.S.
Environmental Protection Agency.
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LiliaA. Abron-Robinson and Leon W. Weinberger are with PEER Consultants,
Inc., Rockville, MD 20852.
Gerald Stern is the EPA Project Officer (see below).
The complete report, entitled "Sewage Sludge Versus Commercial Methods for
Reclaiming Strip-Mine Soils,"(Order No. PB 85-107 779; Cost: $13.00,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
U S GOVERNMENT PRINTING OFFICE; 1984 — 559-016/7850
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
DEC 11-31 ; :;:,;,,,Tf PERMIT NO. G-35 j-
Official Business
Penalty for Private Use $300
"'•-,. OK >c,,.
AGENCY
CHICAGO IL 60604
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