United States
Environmental Protection
Agency
Laboratory
Research and Development
EPA-600/S2-83-055 Aug. 1983
&EPA Project Summary
Standardized Procedures for
Planting Vegetation on
Completed Sanitary Landfills
Edward F. Oilman, Franklin B. Flower, and Ida A. Leone
A manual was developed for those
charged with establishing a vegetative
cover on completed landfills. Special
problems associated with grownig
plants on these sites are discussed, and
step-by-step procedures are given for
converting a closed landfill to a variety
of end uses requiring a vegetative
cover. Instructions are given for
vegetating landfills with either limited
or adequate funds. A hypothetical case
of landfill conversion is also included.
This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory, Cincinnati, 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 back).
Introduction
Completed landfills throughout the
United States are being developed into
parks, golf courses, nature areas, and
other multiple-use facilities. An effective
vegetative stand must be established and
maintained on the final cover soil to
achieve one of these successful end uses,
however. This manual was written for
those charged with establishing such a
vegetative cover.
Step-by-step procedures are given for
vegetating a completed landfill with
either limited or adequate funds. Each
step is to be performed in sequence. A
hypothetical case of landfill conversion to
a multiple-use recreational facility is also
described to illustrate the procedures
outlined in the manual. This hypothetical
site includes a nine-hole golf course,
botanical garden, toboggan run, picnic
area, nature area, tree and shrub nursery,
bicycle paths, and campgrounds.
Data were collected from more than 60
site visits in 21 states, other field experi-
ences, textbooks, and standard
references on the growth of plants under
adverse conditions.
Vegetating Landfills with
Limited Funds
Step A-1. Selecting an End Use
An end use should be selected as soon
as possible. In cases where funds are
limited, the plan might include a park, a
hunting ground, or a natural open space
for trees, shrubs, and grasses. Intensive
recreational uses such as golf courses
require greater expenditures.
Step A-2. Determining Depth of
Cover
Cover soil must be at least 60 cm deep
for grass establishment and 90 cm for
trees. Soil depth can be determined with
a backhoe or a soil auger and shovel. A
minimum of one hole per acre should be
dug for large sites (50 acres) and two
holes per acre for smaller areas. When
funds are limited, trees may be planted
wherever 90 cm of cover soil exists, or
soil maybe moved from one section of the
site to the area desired for tree planting.
Step A-3. Establishing an
Erosion Control Program
The soil on recently covered landfills
must be stabilized soon after spreaing to
prevent erosion. Because the soil is
frequently of poor quality and growing
conditions are often adverse, a one-
growing-season study should be
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conducted to select landfill-tolerant
grasses. Seeds should be handspread
and raked into the soil. Mulch and tack
should be usedto hold the seed in place in
sloping areas and to conserve moisture.
Microterracing is recommended before
seeding and mulching for steep, sloping
ground. Grass and ground cover growth
should be evaluated once a month by a
qualified specialist during the first 4 to 6
months.
Step A-4. Determining the Soil
Nutrient Status
Before or during the grass and ground
cover experiments, soil tests should be
made for pH, major nutrients (nitrogen,
potassium, and phosphorus),
conductivity, bulk density, and organic
matter. Samples should be collected over
the entire landfill in a number of areas
within the proposed planting sites. The
local county agricultural agent or soil
conservation service office can help
evaluate site specific problems and
recommend the addition of fertilizer or
lime.
Step A-5. Determining Soil Bulk
Density
Cover soil is frequently compacted by
landfill equipment during spreading
operations to bulk densities that will
severely restrict plant root growth. Bulk
density can be determined by weighing
two or three undisturbed soil cores of a
known value for each acre. Compacted
soil should at least be scarified and
organic matter should be added to
enhance the physical properties.
Step A-6. Amending Cover Soil
The soil over the entire planting area
should be amended with lime, fertilizer,
and/or organic matter according to the
recommendations from the soils
laboratory one to several weeks before
planting. These materials should be
incorporated into the top 15 cm of soil.
Step A-7. Selecting Landfill-
Tolerant Species
Grasses and other ground covers can
be selected for planting in the soil cover
by evaluating the results of the experi-
mental plots established earlier to
determine landfill-tolerant species.
Step A-8. Planting Grass and
Ground Covers
No studies have been done to define
the best planting techniques for estab-
lishing grasses on landfills, but it is
generally desirable to embed the seed in
the soil. Mulches have been used as an
alternative to embedding the seed, but
this approach is less likely to be effective
on adverse growing sites such as landfills.
Mulches must be used on steep slopes
where embedding or drilling is impossible.
Special techniques such as hydroseeding
may be used on steep slopes inaccessible
to conventional equipment. Gently
sloping or flat sites may be planted by any
of a number of methods (hand spreading,
cyclone spreading, drilling,furrowing, etc.).
Barren areas where plants will not grow
because of high landfill gas concentra-
tions may have to be landscaped with
wood chips or large stones to prevent
erosion and provide a pleasing
appearance.
Step A-9. Developing Tree and
Shrub Growth
Trees and shrubs should not be planted
for 1 or 2 years after grass has been
planted. If the grass cannot grow because
of gases from the landfill, other deeper-
rooted species are not likely to thrive
either.
To develop a good cover of woody
plants, 90 cm of soil must be in place. If
funds are available, a barrier should be
placed beneath each tree-planting area to
protect the root system from harmful
landfill gases.
Vegetating Landfills with
Adequate Funds
Step B-1. Constructing the
Landfill
A successful vegetation program is
more likely to be implemented if the end
use plan has been established before
construction or closure of the landfill. If
such a plan has been developed, steps
can then be taken to minimize gas
production and surface settlement
accordingly. Final contouring can also be
planned to hinder erosion and promote
vegetation.
Step B-2. Extracting Gas
The most successful landfill-to-park
conversions will incorporate a gas
extraction system in the landfill to reduce
the volume of gases escaping into the
final soil cover and inhibiting root growth.
These systems will be compatible with
gas recovery operations and may
eventually pay for some park construction
and maintenance.
Step B-3. Selecting Gas Barriers
Landfill gases may migrate into the
final cover soil even with a commercial
gas extraction system in operation. The
best procedure is to cover the entire
landfill with an impervious soil layer or
synthetic membrane to keep gases from
entering the final cover soil. But if funds
are not available for such extensive
barriers, they should at least be installed
i n areas where trees and shrubs are to be
planted.
A variety of barriers are currently
available to control gas migration,
including a 30- to 60-cm-thick layer of
impermeable clay followed by 60+ cm of
fertile soil, polyvinyl chloride, hypalon,
and other types of membrane sheeting.
Step B-4. Selecting Cover Soil
Though final cover soils may be
costly and difficult to obtain, they are
essential to the success of any
revegetation program. A soil should be
chosen with a texture resembling loam
for areas where trees and shrubs will be
planted, since they require looser, deeper
soil for root development than do grasses
and ground covers. The soil should be
tested for pH, Mg, Ca, P, K, N03, NH4 ,
conductivity, Cu, Fe, Zn, Mn, particle size
distribution, bulk density, and organic
matter. The soil should be tested before it
is delivered to the site, since it can be
easily amended before or during spread-
ing.
Step B-5. Spreading Cover Soil
The clay soil layers should be spread
over the final refuse layers to prevent
infiltration of precipitation. Final cover
soil should then be placed using special
methods to avoid compacting. The
avoidance or elimination of these
compacted layers can be the key to a
successful reclamation project.
Step B-6. Providing Proper Soil
Depth
Areas in which trees and shrubs are to
be planted should be spread with 90 cm of
cover soil, with the top 20 cm consisting
of topsoil to accommodate most of the
fine feeder roots. At least 60 cm of cover
soil should be spread in areas where
grasses and other stabilizing vegetation
will be grown.
Step B-7. Locating Areas
Unsuited for Tree and Shrub
Growth
Areas unsuited for tree and shrub
growth may be identified by several
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indicators: dead vegetation, no
vegetation, anaerobic soil, high soil
temperatures, and thin cover soil.
Step B-8. Selecting Tree and
Shrub Material
Factors to be considered in choosing
tree species to be planted include end use
of the landfill, geographic location, type of
refuse in the landfill, and characteristics
of the species (growth rate, final size,
rooting depth, flood tolerance,
mycorrhizal fungi, and pathology).
Step B-9. Planting and
Maintaining Vegetation
Special planting instructions must be
followed for specific areas, species, and
types of planting materials. The principles
of maintaining plant material on
completed landfills arethe same asthose
for nonlandfill areas, except that addi-
tional irrigation is required.
The full report was submitted in
fulfillment of Grant No. CR-807673 by
Rutgers University under the sponsorship
of the U.S. Environmental Protection
Agency.
Edward F. Oilman, Franklin B. Flower, and Ida A. Leone are with Cook College,
Rutgers University, New Brunswick, NJ 08903.
Robert E. Landreth is the EPA Project Officer (see below).
The complete report, entitled "Standardized Procedures for Planting Vegetation
on Completed Sanitary Landfills," (Order No. PB 83-241 018; Cost: $8.50,
subject to 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
tfUS GOVERNMENT PRINTING OFFICE 1983-659-W7/7167
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Environmental Protection
Agency
Center for Environmental Research
Information
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