,STANDARDIZED PROCEDURES FOR PLANTING VEGETATION^
            i"~"      ON COMPLETED SANITARY LANDFILLS
          3-1/8'
		 __ __ 	1_ __ ,;_-]
         Edward  F.  Gilman
,„.,	Franklin B.  Flower	
           Ida A.  Leone
        Rutgers  University
 New  Brunswick,  New Jersey  08903

            l
                           Grant No.  CR807673
                             Project Officer
            i               Robert E. Landreth
            '•   Solid and Hazardous Waste Research Division
            j   Municipal Environmental Research Laboratory
                         Cincinnati, Ohio  45268
               MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
                   OFFICE OF RESEARCH AND  DEVELOPMENT'
                  U.S. ENVIRONMENTAL PROTECTION AGENCY
              	CINCINNATI, OHIO  45268  . .  - 	

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                A
                                   DISCLAIMER
!      The information in this document has been funded wholly or in part by
i  the United States Environmental Protection Agency under assistance agreement
I  number CR807673 to Rutgers University.   It has been subject to the Agency's
i  peer and administrative review, and it  has been approved for publication as
i  an EPA document.  Mention of trade names or commercial products does not
  constitute endorsement or recommendation for use.

                                      ii

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                                    FOREWORD
      The U.S.  Environmental Protection Agency was created because of
  increasing public and government concern about the dangers of pollution to  j
  the health and welfare of the American people.  Noxious air,  foul water, and
  spoiled land  are tragic testimonies to the deterioration of our natural
  environment,   the complexity of that environment and the interplay of its
  components require a concentrated and integrated attack on the the problem.

      Research  and development is that necessary first step in problem
  solution,  and it involves defining the problem,  measuring its impact, and
  searching  for solutions.   The Municipal Environmental Research Laboratory
 e
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     NS
Ht.RE
ABSTRACT
             A manual was developed for those charged with establishing  a vegetative
         cover on completed landfills.  Special problems associated with growing
         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 report was submitted in fulfillment of Grant No. CR-807673 by
         Rutgers University under the sponsorship of the U.S. Enviromental Protection
         ^Agency.—This-ireport1 covers-the-period-August-1980 to July"1982,~and work  -^
         was completed as of July 1982.       j                                       i
                     9-1/8"

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'  !


  i
  !

JS|—
"3^
                                  CONTENTS
                                     i
Foreword ...
Abstract . . .i
Figures. . . .j
Tables . . . .'
Acknowledgment
              I
    1.   Introduction	j	
    2.   Vegetating Landfills with Limited Funds
                         Selecting an end use	
                         Determining depth of cover. .. 	  ..
                         Establishing~an~erosion-control- program-.—7 —
                         Determining the soil nutrient status	
                         Determining soil bulk density 	
                         Amending cover soil 	
                         Selecting landfill-tolerant species 	
                         Planting grass and ground covers	
                         Developing tree and shrub growth	
         Vegetating Landfills with Adequate Funds	
              Step B-l:  Contructing the landfill	
                         Extracting gas	
                         Selecting gas barriers	
                         Selecting cover soil	
                         Spreading cover soil	
                         Soil depth. :	
                         Locating areas unsuited for tree and shrub
                         growth.	
                         Selecting tree and shrub material 	
                         Planting and maintaining vegetation 	
                 Step A-l
                 Step A-2
     	Step 'A-3
                 Step A-4
                 Step A-5
                 Step A-6
                 Step A-7
               9'1Step A-8
                 Step A-9
       3.

                 Step B-2:
                 Step B-3:
                 Step B-4:
                 Step B-5:
                 Step B-6:
                 Step B-7:
                 "Step B-8:
                 Step B-9:
    4.   Landfill Conversion:  A Hypothetical Case
References
    v
   vi
  vii
 viii.
     !
     i
    1
    2
    2
    2.
— 3-4
    9
   10
   10
   10
   11
 - 12
   13
   13
   14
   15
   16
   19
   20

   22
   24
   32
   35

   37
 5PA-237

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CHOPPED
HEAD.
3EG1M
                                             FIGURES
        j Number         i                       I                                Paee
        , —^_«___         j                                                       •*• c*&g*

        j    1   Suggested grid pattern  for  sampling soil depth on a
        i           50-acre site	,	3
        i                '                       I
                        i                       i
            2   Experimental design plan  for  testing tolerance of
                   grass species  to landfill. .1	.5
            -3- —
Gas -protection scheme using -synthetic-membrane-covering	• —
   large areas of former refuse	15
        i                       !
Good tree and grass growth in  75-cm soil mound  over  a
   3-cm thick layer of bentonite	17
                      i- i/ 0
            5   Gas prevention scheme  for  small  planters	17
                        !                       i
            6   Gas prevention scheme  for  vegetation planting island in a
                   paved parking  lot over  a  former  refuse landfill	18
                        !                       i
            7   Area with shallow cover  soil and consequently little or
                   no plant growth	22
                        1                       i
            8   Excavated green ash on landfill  showing most roots in top
                   soil layer	28
                       ~!              -        '
            9   Excavated green ash in control area showing even distribution
                   of root system.............;................„....... „..... „. 29
              3'8"
           c?A-i2? O;;i.
           • 1-751

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3EG":   j
                                           TABLES
            Number
                                                           Page
                   Some grasses and legumes  that should be  tested
                      for landfill adaptability	
                                                           ...5

                                                           ,6-7
               2   Suggested herbaceous species for erosion  control	
                        1                       i
              —3 — Preferred:varieties of seed -for- erosion-control -on	
                      Pennsylvania landfills.. I	8
                   Some'slow, moderate, and rapid  growing  tree  species
                      found in the United States	
                     9-1/8"                     |
                        t                       '
                   Volunteer  (pioneer) species  indigenous  to various
                      geographical areas of the United  States	
               6


               7
Vertical distribution of tree roots in landfill and
   non-landfill soil	'.	
Some small trees and shrubs  (less than 9 m  tall
   at maturity)	;	
,25


,26


.27


,31
            * 3/8'
                'Gin.

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                         A
  CROPPED
  SECTIONS
r
                                             SECTION 1
                                           INTRODUCTION
               Completed landfills throughout the United States are being  developed
           into parks, golf courses, nature areas, and other multiple-use  facilities.
           A critical factor in achieving one of these end uses is establishing  and
           maintaining an effective vegetative stand on the final cover  soil.  This
           manual is written for those charged with establishing such  a  cover.   The
           special problems of growing plants on completed landfills are discussed,  and
           step-by-step procedures are given for converting a closed landfill  to a
           variety of end'uses that require a vegetative cover.
               The manual;has three major sections:  Vegetating  a completed  landfill    j
           with limited funds, vegetating a completed landfill with adequate funds, and
           converting a hypothetical  landfill to a multiple-use  recreational facility   1
           with adequate  funds.                 I
                       9-1/8"
                          !                      1
               Each section presents  a series of steps to be performed  in sequence.
           Data were collected from more than 60 visits to  landfills  in 21 states
           (Flower et al., 1981 and Leone et al.', 1979), other experiences in the
           field, textbooks, and standard references on the growth of plants under
           adverse conditions.                  j
                                                i
            £:jA-237 ;c,n.
            1-+-/01

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DnOPPSD i
HEAD,   j
nr.-'M   i
O£OUV   i
SECTIONS;
H5?E   13
                                          SECTION 2
                            VEGETATING LANDFILLS WITH LIMITED FUNDS
           STEP  A-l.   SELECTING AN END USE
                        i
                The process  of  selecting  an end. use for a particular landfill will be
           largely  dictated  by  local  needs  and  the politcal community.   The selection
           should take place as soon  as possible to expedite initiation of all steps
           required to complete the project.  Accomplishing each step will be much
           easier once a plan has.,been formulated.  In cases_where_funds_ are_limited,
           the "plan mTghlE include a passive park,  a hunting ground,  or  a natural
           open  space where  trees, shrubs,  and  grasses will be planted.  (Golf
           courses, multiple-use  parks, and other highly intensive recreational
           uses  would require greater expenditures and will be covered  in Section 2 )
           If an end  use has not  been selected,  then controlling erosion will be the
           primary  short-term goal (see Step A-3).

                        1                       '
           STEP  A-2.   DETERMINING DEPTH OF  COVER
                        i                       i
                Probably because  of high  costs  and lack of availability, the amount
           and quality of soil  covering the refuse in a landfill has frequently been
           found to be inadequate for vegetation growth.  Such deficiencies need to
           be corrected before grass or woody vegetation is planted.   The cost of
           covering an entire landfill with enough rich soil for satisfactory tree
           growth is  excessive.  Therefore, enough soil should be present to bring
           the total  depth to 60  cm (not  including the gas barrier layer) in all
           areas except where trees and shrubs  will be planted; the latter areas
           require  at least  90  cm. If portions of the landfill have no cover soil
           over  the final refuse  layer, select  and spread soil according to steps
           B-4 and  B-5. j                      i
                        '                      i
                A back-hoe is best suited for determining soil depth, because many
           holes can  be dug  in  a  short time.  If this equipment is unavailable, a
           soil  auger and shovel  can  be used.  Because soil depth generally varies
           over  the landfill, several determinations should be made at different
           points in  the'area to  be planted (Fig. 1).
                                                                                       50TTC
                                                                                       IMAGE
                                                                                       CUTS!
 •^ 3/8"      ---,
 1	L

5A-;37 (Cm.)
                                                                                        TrATH

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UMw'i ~r!_'
HEAD

s»-








90
'•90 	
90
*


70
•

70

i
i
90
f
— 90
1
ds
1
i
60
*
)
80
f

85
— 90
80
•


50

80


90
"'"90 "
70


40

90


8?.
• 80
70


20

80
*

85
/b
*
20


20

80


85
•~75~~
20


10
*

40


90
" 70
*
20


40

50


9p
70
30


90

80


9.0
85
45
*


90

80
•
i
1
1
i






        I
                        Figure

                      9-1/3"
           Suggested grid pattern for sampling soil
           depth on a 50-acre site (values, in cm).
           By  digging a minimum of one hole per acre for large sites (>50 acres) and  i
           two holes  per,acre  for smaller areas,, enough data can be collected to make  i
           an  adequate determination of whether additional soil is necessary, how
           much is  needed,  and where it should be placed.   Follow the procedures in
           Steps B-4  and B-5 when selecting and spreading additional soil cover.

                Fifty holes are dug in a grid-like pattern with a back-hoe, and soil
           depth is measured in each hole and recorded on a map of the site
           (Figure  1).   The results show that more soil is needed in the center of
           the site.   Two options are available to the landscaped •. 1) soil can be moved
           from the northwest  end of the fill to the center, or 2) soil can be        j
           trucked  in from  another site and spread in the center.  Moving the soil is j
           the obvious choice  if trees are not to be planted in the northwest end and j
           if  the soil is of good quality (see Step A-4).   If the soil is poor,
           however, and a stand of trees is desirable (e.g., as a source of food and
           cover for  wildlife), consider bringing soil of a higher quality for the
           center and planting the trees there.'  If the cover soil on the site is
           suitable for tree growth in some areas (see Step A-4), supply soil in the
           center to  a depth of 60 cm for grass establishment and plant the trees
           wherever there is enough soil for tree root development (i.e. 90 cm).
7
                                                                                       SO: K
                                                                                       iMAG'
                                                                                       CUTS
                                                                                     ^»i
                                                                                       TP.AT:
           i?A-237
           •4-7S5

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DRC°?
r-E^O.
"STEP A-3.   ESTABLISHING AN EROSION CONTROL PROGRAM                      —
                                    !
 Testing Tolerance of Ground Cover Species
              I                      I
      The soil on recently covered landfills must be stabilized  soon after
-spreading  to prevent erosion.   But the combination of soil conditions   —
-found-on-completed -landfills- is not found-in -other-areas.—Soil-concen	
 rations of C02 and CIfy  can be high, and 02 can be low.   The soil is
 frequently of poor quality,  soil moisture is often limiting,  compacted
 soil is common,  soil temperatures can be high,  and exposure to  weather
 can be extreme.   Furthermore,  little  is known  about grass  and ground cover
 adaptability to landfills,  and tolerant species have not been identified.
 Since no research has been published  on establishing grasses on landfills,
 a  one-growing-season study should be  conducted to select landfill-tolerant
 grasses.   Such studies  can be easily  performed during the operation of the
 active portion of the landfill.   About 2 acres will accommodate-, the
 following  experiments.
           	First, -select -several-closed-, areas-that-will- remain .undisturbed-Jfor
           at  least  one growing-season  if  the  landfill  is  still active.   If the fill !
           is  above  ground,  five  areas  will  be required—one on the flattened top,  and
           one on each  of  the  four  compass cardinal-point  side-slopes  of the landfill,
           since species growth requirements may be  specific for different  exposures.
                     9-1/8"                    j
                The  conditions at the experimental plots must represent  those expected
           over most of the  fill  area if meaningful  conclusions are to be drawn.      j
           Conditions that should be considered  include  (1)  cover soil depth, type,
           and compaction, (2)  soil gas concentrations,  (3)  refuse type, depth,
           age,  and  compaction, and (4) surface  aspect and slope.
                        !                      |
                Soils in the experimental  plots  should be  tested for pH, Mg,  Ca,  P,
           K,  N03, NH4,  conductivity, Cu,  Fe,  Zn, Mn, particle size distribution, bulk
          -density,  and organic matter.. Four  to five samples should be  collected per !
           acre.   Step  A-4 gives  the details on  collecting these samples.  Soil tests 'l
           should be performed by the State  Agricultural Experiment Station or other
           certified soil  testing laboratory to  indicate whether amendments and/or
           conditioning is required for acceptable seed germination and  growth.
           These amendments  should  be applied  according to soil test recommendations
           and mixed into  the  top 15 cm before the plot is seeded.

                Each test  area should be divided into at least three blocks and
           each block should be planted with all the species being evaluated in 9-
           to~18m2 plots delineated by  string  (Figure 2).   This will provide three
           replications 'of every  species in  each area.  The species should  be randomly
           distributed  within  each  block.  Hand  seeding will be necessary.   Twenty   i
           or  more species can be easily handled in  this manner.                     !
                        I                      !                                       I
                                                                                     I SOTiC
                                                                                     i  IMAGE
                                                                                     !  CUTS!
                                                                                     7  C!M=;-,
            2 3/B"
                                                                                     >AND
                'C',',:.)
          . 4-76!

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    DROPPED I
    HEAD.
    BEGIN
  X
I  v_/
,'S*


1
2__

3
4
5
6

7
— 8-
9
10
11
12
13

14
15
16
17
18
19
-20
21
22
23
24
17
18 -
19
20
21
22
23

24
1
2
3
4

5
<*
o
7
8
9
10
11
-12-
13
14
15
16
3

4
5
6
7
8
9

10
11
12
13
14
15
16-
17
18
19
20
21
— *%rt .
2.2.
23
24
1
2
               	Block; 1/2*
                              _Block-2	Block 3	
                          Figure 2.  Experimental design plan for testing  tolerance
                           I          of grass species to landfill.  Numbers  in blocks
                           j          indicate different species.
                         9-1/8"
                    Seed companies and the State Agricultural Experiment Station are
               likely to cooperate in selecting species with which to experiment.  In
               most cases,  seed varieties should be chosen to accomodate very dry sites
               and the cover soil conditions particular to the landfill (these .should be
               checked by testing the soil as in Step A-4),  Species selection may require'
               more care on fills with a known end use, since aesthetics and compatability
               with the end use must be considered along with erosion control.  A list    j
               of  species that have been recommended for strip mines or other difficult-
               to  reclaim areas are listed- in Table 1.
                     TABLE 1.   SOME GRASSES AND LEGUMES THAT  SHOULD  BE  TESTED
                           I               FOR LANDFILL ADAPTABILITY3
              Grasses
                                                 Legumes
    3EG:
    LAG'
    OF •
 Kentucky 31 Festuca arandinacea
 Perennial ryegrass Lolium perenne
 Weeping lovegrass Eragrostis curvulara
 Millet Echinochloa spp.
 Reed canary Phalaris arundinacea
 Switchgrass Panicum virgatum
-Orchard grass Dactylis glomerata
                                                       Crownvetch Coronilla varia
                                                       Birdsfoot trefoil  Lotus corniculatus
                                                       Alfalfa Medicago sativa
                                                       Lespedeza Lespedeza  spp.
                                                       Flatpea Lathyrus
              aReference: Vogel, 1981
 30TTC
 I MAGI
 GUTS
\ Dl.V.Ef
j ~CR T


              EPA-237 (Cin.)
              '4-761
                                                    • MBFR

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M . 1
TABLE 2. SUGGESTED HERBACEOUS SPECIES FOR EROSION CONTROL
Geographic
Regions
Northeast &
North Central U.S
and Northern
Appalachia
•
Mid and southern
Appalachia,
western
Kentucky,
Arkansas,
Oklahoma
I
S ? 1 1 3
Seeding
Time
Early spring
to
mid-spring
Mid-spring
- -~ • to ~ " " '
mid-summer
Late summer
to
early fall
Early spring
to
mid-spring
Late summer
to
early fall

Temporary (quick cover annual) Permanent (L<
_j 	 species3 	 i, 	 J 	 perennial t
(use one with permanent mix)
Name Seeding rjate Name
(Ib/acre)
Annual ryegrass
Perennial ryegrass
Oats
Weeping lovegrass
Foxtail millet
• - "Japanese millet" """
Weeping lovegrass
Rye
Winter wheat
Annual ryegrass
Perennial ryegrass
Oats
Weeping lovegrass
Annual ryegrass
Rye
Winter wheat
Annual ryegrass
Perennial ryegrass
Crimson
s"\
1
25 |
»!
10 1
1
.... . ^ i
so r
10 |
I
80 j
80 '
25 t
i
50 i
75 1
25 !
80 j
80 I
25
50 1
50 |
f

Ky-31 Tall fescue
Birdsfoot trefoil i
Crownvetch or
Flatpea
1
t
i
|
?ng lived)
species 	 ^
Seeding rate ,
(Ib/acre)
md 75
Jr 30
50
80
Ky-31 Tall fescue and 75
Birdsfoot trefoil <
Crownvetch or
Flatpea
Ky-31 Tall fescue j
Birdsfoot trefoil <
Crownvetch
Ky-31 Tall fescue a
Korean and/or Kobe
Lespedezac or
Crownvetch
Ky-31 Tall fescue
Sericea lespedeza
(1/2 unhulled seet
Crownvetch
sr 30
50 ,
80 ;
md 75
>r 30
50
md 75
i
50 j
50
and 75
)~ or 50 i
50
r\ '

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                                                                                              n.
in

r
I "1 I ~ 0J
-n fV %
>: r *~
--i :-;
'.'if r"
..../r_
h;u •
1 t.,> -i 	
co
Geographic
Regions
Mid and
Southern
Appalachia
:'.:j:j: Illinois,
:':•: Indiana,
""* Iowa,
'••' Northern
•;: :'j: Missouri
Missouri,
Kansas,
Oklahoma
— Use only
of each
TABLE 2. (continued)
Seeding
Time
Early-spring
to
mid-spring
Early spring
to
^mid- spring
Early spring
to
mid-spring
Late summer
to
early fall
one of the temporary
species in proportion
'v ,/

1
Temporary (quick cover an
species
(use one with permanent m
^ ' _,.,..,,-. 	 „. . 	 ~ . —___
Name Seeding ra
(Ib/acre
Weeping lovegrass
Sorghums
Pearl millet
' Foxtail millet
Browntop millet
Oats
Annual ryegrass
	 Perennial ryegrass
Oats
Winter wheat
Rye
species at rates shown
to number used (i.e.,
10 *
80
50
50
.. fin
75
25
	 50-
75
120
120
. If more
for two spe
r

	
nual) Permanent (Lon
perennial sp
lx)
te Name
-? Ky-31 Tall fescue
Sericea lespedeza^
Korean and/or Kobe
Lespedeza —'
Ky-31 Tall fescue
Smooth bromegrass
Alfalfa or ' '
Birdsfoot trefoil
Crown vetch
Ky-31 Tall fescue
Alfalfa or
Crownvetch
Ky-31 Tall fescue
Alfalfa
than one is used, reduce
:cies, use half the seed:!
i
rii  •
"'• :•:• :;: a 1 .'"
< ) " ,n
::< a
W ':': 	 _ , t
'i i1
g lived )
acies
Seeding rate
(Ib/acre)
and 75
or 50
50
or . 75
and 75-
— 50— 	
or 30
50


:
and 75
50
50
and 75
50
seeding rate |
ing rate of each)
  L.^,
Ji'Half or more ot Sericea lespeaeza seea snouia oe unnuiieu auu uusuaj
  germination and insure sufficient seed for germination next spring.

                                                                 I                        ,
S-'fhese annual lespedezas usually reseed each year and may become a permanent component c
                                                                                                f jthe
   -1 )•> '11  .
   >   -  <

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 -     The experiments should be planned so that seed can be sown preferably
  in the fall,  or where necessary, in the very early spring.   The seeding rate,
  which varies  with the species, can be suggested by the seed supplier.  Seed
  companies and soil conservationists generally recommend that the seeding   j
  rate be several times that specified for undisturbed lands.  Several
 ..legumes (Table 1) should be tested along with the grasses; since they   	1
 jLre_widely_ adaptableland_require,.far.,less_nitrogen_j£or.., growth, .-they.-.are	j
  often used for reclamation purposes.''                                       j
               '                       '                                       i
       Mixtures .of annual and perennial species (Table 2) are reported to be
  best suited for stabilizing soil and protecting against erosion on reclaimed
  strip mines.  iThe annual plants provide a quick temporary cover that is
  succeeded by  a more permanent perennial species.  Seeding rate recommend-
  ations should be followed carefully for the quick-cover species, because
  higher rates  could produce dense stands that prevent or retard establishment
  of the permanent species.
               i
       If it becomes necessary to cover portions of the landfill with soil-
  holding grasses__before. the_experiments Jiave been_cgmpleted,_then_the	
  ,r    _, •^r-£-cuYtu^ai agent or soil conservation service can supply the
  standard seeding and feeding rate (based on the soil analysis outlined in
  Step A-4) for that area for the species selected from Table 1 or otherwise
  recommended by the county agent.    !

       Mixtures"for spring and fall seeding are suggested in Table 2.  Some
  of the mixtures suited for erosion control and site stabilization are not
  compatible with other land uses.  For example, Sericea lespedeza and
  flatpea are excellent for long-term erosion control, but their value as
  forage and wildlife habitat is lower than that of other legume species.
  Species should thus be selected for their suitability for  the approved
  land use as well as for their ability to control erosion.  Some specific-
  ations are given in Table 3 for erosion control plantings  found to be
  adapted to conditions on landfill sites in Pennsylvania (Swope, 1975).
                i                       !
         TABLE 3.  PREFERRED VARIETIES OF SEED FOR EROSION CONTROL
                             ON PENNSYLVANIA LANDFILLS
i  Species       |
!
i  Tall fescue   I
  Birdsfoot trefoil
  Crownvetch    '
Variety
   K-31
   Empire
   Penngift
Lbs/Aere

  20
   4
   6
                                  PAGE .^

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DROPP
HEAD;
   Planting Procedures                 j
                                       i
        The best procedure to prevent erosion is to microterrace steep,
   sloping ground before seeding and mulching.   Microterracing can be
   accomplished by running a wide-tracked bulldozer up and down the slope
'—without touching the soil with the blade,  to create a series of ridges  —
  -and -troughs-across-the-side-of-the-slope -that-will—help ~prevent~erosion—
   and aid in seed germination and growth.
                i                       !
        The seed should be handspread in each subdivision and raked into the
   soil.  A mulch and tack designed to hold the seed in place should be
   applied to sloping areas where grass seed has been planted to prevent
   the seed and soil from washing out during heavy rains and to help keep
   moisture in the soil.  Some of the annuals can be seeded in the spring
   and then cut and used as a mulch in a fall perennial planting.
  •oi -i. :±:
                Grass  and  ground-cover growth should be evaluated once a month by a
           qualified specialist during the first 4 to 6 months following seed
                i                       i
        The soil' on landfills that have been covered and completed for 1 or
   more years may have volunteer and planted vegetation that was placed there
   before plans were developed for a specific end use.  If the particular use
   will include-'a?natural area,  consider testing those species that are
   already volunteering on the site.  These are likely to. include a variety
   of annual species if the site is young,  or perennials if the site has been
   established for 2 or more years.  Begin these experiments in the fall so
   that the following three steps (determining soil nutrients and bulk
   density and amending the cover soil) can be implemented during the next
  summer.  Planting over the entire landfill can thus be done the following
  fall.         |                       j
   STEP A-4.   DETERMINING THE SOIL NUTRIENT STATUS
                '                       S
   Sampling Procedure                  j

        Before or during the grass and ground cover experiments,  soil tests
   should be made for pH, the major nutrients (nitrogen, potassium, and
   phosphorus), conductivity, bulk density, and organic matter.  Where
   possible,  tests should be made for the other macro-and micro-nutrients
   mentioned in Step A-3.  Soil samples for these tests should be collected
   over the entire landfill in a number of areas within the proposed planting
   sites.  A grid or zig-zag sample pattern should be used.  If the cover
   soil is homogeneous and originated from a single source then one sample
   for each 5 acres may be sufficient. 1 But if a wide variety of materials
   were used as cover, then a more frequent sampling pattern should be
   designed.   Samples should be collected from a 0 to 20-cm-deep  soil column.
   Five subsamples should be collected over an area and pooled to form a single
   composite sample.  Any of a number of soil auger types or shovels may be   j
   used to obtain samples (picks and shovels may be required in very compacted
   soils).  Decaying plant material, roots, etc. should be removed from the	!
   sample.      '                       •                                       ;
                                                                                       OUTSi
                                 '•••<: •:. 9
                                                                                       THAT;
           SPA-237 (Cin.i
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        !Fertilizer
                        !
DROPPED
HEAD;
BEGIN
SECTION;
HERE   ';
 EEGiM
    EXi
      The local county agricultural agent or soil conservation service office
 may help to collect and analyze the samples, interpret the results, and make
 recommendations for the addition of fertilizer and/or lime.  Remember      j
"however, that fertilizer may encourage such rapid, vigorous growth of      |
-the -herbaceous—vegetation"thatr the~establishment~of "woody ~species~f rom     |
 seed may be supressed or prevented. ,' Again, such site-specific problems    ]
 must be worked out with local officials and reclamation specialists
              i
 Metals       i

      Soils that contain high concentrations of zinc, copper, manganese,
 iron, cadmi,um, or lead should not be. used for cover material unless this
 situation can be corrected by increasing the pH between 6.5 and 7.0,
 increasing the phosphorus content or. adding organic matter.  Studies are
 available on the relationship of the' metal contents of soils to plant
 growth (Chaney, 1973).
(f-	!• — 6-1/2"	-i	•
 Conductivity !
 	  1                       1
              !                       i
      Conductivity is an important soil characteristic that is frequently
 neglected in routine analysis.  Since salt content can dramatically affect
 plant root growth and water balance, avoid planting in soils with a
 conductivity greater than 2  miaohs /cm.  Soils with greater conductivity
 can be used only after rain water has leached enough salt from the soil
 to bring it within acceptable limits, (i.e., less than 2  mmohs ) •  This
 process may take several weeks or months, depending on the amount of
 rainfall and drainage characteristics.  Salts may never leach from soils
 in the drier parts of the country.  Conductivity tests can be performed
 along with the more routine analyses.
              i                      I
 STEP A-5.  DETERMINING SOIL BULK DENSITY
              i                      i
      Cover soil is frequently compacted by landfill equipment during
 spreading operations to bulk densities exceeding 2. fj g/cm3.  Bulk density
 can be determined by weighing two or; three undisturbed soil cores of a
 known volume(e.g., 300 cm3) for each acre.  If the  density is greater
 than 1.7 to Ii8 g/cm3, plant root growth will probably be  severely
 restricted (Bohrn, 1979).  Compacted soil should at  least be scarified,
 and organic matter added to enhance the physical properties.

 STEP A-6.  AMENDING COVER SOIL
               t
      The soil'over the entire planting area should  be amended with  lime,
 fertilizer, and/or organic matter  according to recommendations from the
 soils  lab one  to  several weeks before anything is  planted.  These materials
 should be incorporated into  the  top 15 cm  of  soil.
        EJ	STEP A-7.  SELECTING LANDFILL-TOLERANT  SPECIES
             1 3/8"      I
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                 (Cin.)

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CROPPED
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*I —    From the results of the experimental plots established in Step A-3,
i  grasses and other ground covers can be selected for planting in the soil
•  cover spread on the entire landfill..
SECTIONS S,
BEGIN
         STEP A-8.  PLANTING GRASS AND GROUND COVERS
                                                           _define.,j;he_best_planting«
    technique for establishing grasses on landfills, but it  is  generally  desirable
    to embed the seed in the soil.  Mulches have been used as an alternative  to  j
    embedding the seed, but this approach is less likely to  be  effective  on ad-  j
    verse growing sites such as landfills.'  On steeper  slopes,  where  embedding or
    drilling is impossible, a mulch must be used to prevent  the surface soil
    layers from drying out and to hold the seed on the  soil  until  it  germinates
    and establishes a reasonable cover.
                   i
    Planting Steep Slopes

         Several methods exist for dispensing seed onto the  cover  soil.   Steep
    slopes that are inaccessible to conventional equipjnent ^st_be_hydrgj-^	
   pprocesse'd"in" 6ne"operation~with"fertilizer, lime, seed,  mulch,  and enough   j
    tack to hold the mulch on the slope.  iHydroseeded soil must not be compacted I
    during spreading and must be very friable at seeding time.  Seed  will germ-
    inate beneath the mulch on hard, compacted soil, but the roots will not
    penetrate the soil surface and will succumb to drought.  Although hydro-
    seeding has been advertised as a miraculous process for  vegetating slopes
    and other areas with adverse growing conditions, results will  be  disappoint-
    ing unless the soil is properly prepared with the right  equipment at  the
    proper time.

    Planting Flat or Gently Sloping Ground
   i	        j                       i
   I      Many methods exist for spreading fertilizer, lime,  seed,  and mulch
   i on flat and gently sloping ground  (hand-spreading,  use of cyclone spreader,
   \ drilling, furrowing, etc.).  The method chosen will be dictated by the soil  j
   ; type and condition, and by other factors particular to the  planting areas
    to be determined by the contractor.  To assure that the  methods used  are
    suited to the existing conditions, these factors should  be  carefully
    studied just prior to planting.

    Barren Areas

         Areas may exist on the landfill cover where plants  will not  grow
    because of high' landfill gas concentrations.  Replanting these areas  will
    generally not eliminate this barren area problem.   Wood  chips  or  large
    stones can be used to prevent erosion and provide an aesthetically pleasing
    appearance.  If! gas is extracted or otherwise recovered  from the  landfill,
    the ability of the cover soil to support vegetation will be increased.
    Further discussion of this matter  is presented in Step B-2.      :-
                                          j
         If no gas is present in the areas of poor growth, the  soil  should be
 i-,ic checked for the constituents listed in Step A-3 and for  erosion washout.
r^^p:! replanting is necessary, the area may first have to be refilled,  regraded
 '" '—and- micro terraced.-	_____	.                                  —.—,-
                                                                                30TTC
                                                                                I MAG!
                                                                                GUTSi
                    _JL
                                                                                TRAT!
           £?A-257 !Ci:i.j
           .'•1-78!
                                           AGE

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•JMU
H£AD,
ScG'.N
SECT'CUS
HSR3   ^
 BEGIN
 LAST L;NE
 Cr TEXT
• STEP A-9.  DEVELOPING TREE AND-SHRUB GROWTH                             "	
             i                       i
      Efforts to develop a good cover of woody plants should begin by
 ascertaining that 90 cm of soil is in place in areas where trees and
 shrubs will  be planted.  Woody plants generally have a deeper root system
.and require  better anchorage than ground cover species.  Soil added to 	
_bring the_j?riginal cover to a depth of 90 cm should_.be,_selec.ted_.and_3pread.
 according  to Steps B-4 and B-5.  If sufficient funds are available, a
 barrier (Step  B-3) should be placed beneath each tree-planting area to
 protect  the root system from harmful landfill gases.
             !                       i
      The least expensive and most practical means for establishing trees
 on a completed landfill that has been closed for some time is to plant
 seeds or small whips of species already establishing themselves on the
 landfill.  Some of these species may be available from the State nursery.
 Since recently closed portions of landfills and older landfills with very
 poor cover material are not likely to support many volunteer trees or
 shrubs, consult Step B-8, a good reference (e.g., Harlow and Harrar, 1969)i
 and/or the county a gricultura^a\gent_to_determine_ which £f the_volunteer
 s~pec~ies~ is" b~est~suited fbV~the~ area;
             I                      i
      After the grass has been planted, a 1-or 2-year waiting period is
 recommended  before areas are selected for planting trees and shrubs.
 If the grass cover with its shallow roots dies or fails to germinate
 because of "the" influx of gases from the landfill, it is nearly certain
 that other deeper-rooted vegetation (trees and shrubs) will not thrive
 at these locations.

      The procedures presented so far represent the bare minimum required
 for establishing plants on a completed landfill.  As the funds for land-
 fill end uses increase the more sophisticated procedures described in the
 next section can be used for establishing grass, shrubs, and trees.
                        t                       i
                Because gas migration into the!root zone will adversely affect the
            survival  rate  of grass,  shrubs, and trees,  active extraction of gas from
            the  refuse layers  is recommended*  This procedure, while effective, is
            expensive.  However, if  the gas can be sold for its heating value, the
            cost of the gas-extraction system may be recovered.  If this procedure
            is not practical,  consider placing gas barriers between the refuse and
            tree roots to  prevent gas migration.   These procedures are covered in
            Steps  B-2 and  B-3.                 I
                                                                             sorrc
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               3/3'
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cp—-nvc
                                          SECTION 3
                                               i
                            VEGETATING LANDFILLS WITH ADEQUATE FUNDS
    STEP  B-l.  CONSTRUCTING THE LANDFILL

         Developing an end-use plan before construction or closure of the
    landfill will increase the likelihood that a successful vegetation
    program can  be implemented.   Factors  to be considered in vegetating a
    former landfill include refuse age, ; type,  dep th,  and compaction; _lpcation  ,
    of" degradable" or" rion-degradable refuse, proportion of refuse to daily
    soil  cover,  amount and type  of final  soil cover,  surcharging of refuse
    with  cover material,  area climate,  final contouring (including maximum
    slope),  and  gas extraction.         j
                 '.
              9-* /3"
    Minimizing "Gas Production

         The amount of landfill  gas produced during refuse decomposition is
    generally  related to  the amount of  putrescible or volatile material de-
    posited in the landfill,  age and depth of landfill, water infiltration,
    etc.  (Emcon  Assoc., 1980).  To minimize gas production, the ratio of
    nondegradable to degradable  material  can be increased by including
    greater quantities of nonputrescibles in the refuse or by increasing the
    ratio of daily cover  to landfilled  refuse.
                 i                      !
         Placing nonputrescibles (glass,  plastics, metals, rubber, concrete,
    etc.) in specific areas to -create nonbiodegradable refuse islands may
    allow plants to grow  in areas relatively free of landfill gases and
    facilitate more efficient resource  recovery in the future, tGases may
    migrate into these zones from areas  containing decomposable material,
    but grass,  shrubs, and trees should  grow better above these islands.

    Minimizing Surface Settlement
                 i
         Surface settlement may  have to be minimized in some areas so that
    irrigation lines can  be installed and maintained to support trees and
    shrubs. Islands of nonputrescible  refuse have minimum surface settlement  j
    and can generally support irrigation  lines without the constant mainten-   j
    ance  required in the  areas containing putrescible refuse, where  frequent   !
    breaks are caused by  uneven  settlement.  Later surface settlement can also
    be minimized by surcharging  the refuse witfi the soil that will be used     ;
     s cover material in  the future or by filling the area with shredded or —;
^Z.—baled-refuse.	i	*,	              . •
             ,  ,
             ?i j \j t
           -PA-237 (Cin.
           M-7R1
                                         /•••••••••• 13 ••:''-'---'\
                                          PAGE NLM8F.R
                                                                                        30TTC
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DROPPED
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3ECN
SECT:ONS
zcrz,
       i   Final Contouring

       i        A. critical consideration in landfill design  is  the  slope of  the final
       i   contours.  A. steep-sided landfill  slope allows  for the placement  of a
       ;   greater volume of refuse, but it also promotes  soil  erosion  and hinders
       ~J~vegetative establishment.  Evidence  indicates that slopes  steeper than
       r  3:l~(hbTizblitaTfvertic~aT.)^nh^
       ;   component during the  closing of a  landfill.  Since recommendations
       !   for maximum allowable slope are still a subject for  discussion, one
       }   must practice good  judgment when grading for final contours.
           STEP B-2.  EXTRACTING GAS
                        i
                The most successful landfill-to-park conversions in the coming
           years will incorporate a gas extraction system in the landfill  to
           reduce the volume of gases escaping into the final soil cover and  inhib-
           iting root growth.  These systems will be compatible with gas recovery
           operations and may .eventually p3y_for^a_poTt±on_o£_the^ park construction
           ati3~maihtehance~requirements.      ~
                        i
           Induced Exhaust Systems
                        i
                Extracting gas from within the refuse fill by an induced exhaust
           system, as "is currently being done in several states, should aid plant
           growth by reducing the quantity and pressure of landfill-generated gas.
           The economic value of the extraction operations may end before  gas
           generation ceases, but successful plant growth may require continuing
           operation of the extraction  equipment.  The soil in which the  vegetation
           established itself probably had a very low gas content: any sudden in-
           crease in gas 'would be likely to cause severe plant stress.
                        i                       I
           Patterns of Gas Contamination       I
           '             j                       I
                The gases of anaerobic refuse  decomposition  (primarily methane and
           carbon dioxide) can migrate- from the refuse layers  into  the cover  soil,
           and in some cases into property adjacent  to the landfill.  The  latter  is
           most likely to occur  at  landfills located  in former stnd  and  gravel pitss
           where the  surrounding soil is very  porous, facilitating  lateral gas flow.
                        !                       ]
                Gas contamination of the cover•soil will not be  uniform ovar  the
           entire landfill site.  Some areas will contain  relatively high carbon
           dioxide  (>25%) and methane  <>40%) concentrations, and consequently low
           oxygen  «6%) .contents.   Other cover soil  areas  may  be influenced very little
           by the underlying refuse material.
    Effect of Climate on Gas Production'
    'j           ~  '         i                            -.
         Site visits to some 60 completed landfills within nine major
    climatic regions of the United States generally revealed a high negative
    :orrelation between plant growth and concentrations of methane and/or
*±	carbon dioxide -in the -root .atmosphere _.(Flower-at._al. ^JL978) <>—Little——
                                                                                        30TTC
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\ — i  . . •• * *•-
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  /'
c
         -variation in the magnitude of landfill gas production and consequent    *	,
         .""vegetation damage was observed among the different climatic regions,  except
         ! for the arid southwest (Arizona), where concentrations of methane  and
         , carbon dioxide were found to be somewhat less than in the either other
         i climatic regions.
                       '  1
         "Gases from Hazardous Wastes
             Very little appears  in the published literature about decomposition
       •i and  gas  generation  in  hazardous waste landfills.   Shen (1981)  states that
        | most organic wastes will  degrade biologically and chemically into gaseous
        i components, but no  data are presented to  support  this statement.
        I
        | STEP B-3.  SELECTING'GAS BARRIERS
                       i
             Since landfill gases may migrate into the final cover soil even with
         a commercial gas extraction system in operation,  special precautions should
         be considered when  planting trees and shrubs.   The best planting procedure ,
         would be to cover the  entire__landfill_with_ain_impervious _soil  layer	.^.J
        e(Iutt6n,~1980)"~of~synthetic lnembVane~to Keep  gases from entering the final ;
         cover soil.  Provision must be  made to release the gases from  beneath      j
         the  impervious layer.   This barrier will  also  prevent water infiltration   1
        j into the underlying refuse  and  thereby reduce  leachate generation.  If
        !such a procedure is economically unfeasible,  then gas barriers should at
        ! least be,.installed  in  areas where trees and shrubs will be planted.  Of
        I course,  the grass or ground cover in other areas  of the fill that do not
        I have gas barriers will be subjected to gas contamination that  may cause
        i patchy areas of poor growth.
        |               j
        !     A variety of barriers  are  currently  available to control  gas migration!.
        |A  30-to-60-cm-thick layer  of impermeable  clay spread over the final       j
        irefuse layer and followed by an adequate  amount (>60 cm)  of  fertile soil   I
        Affectively prevents the upward migration  of landfill gases  into the root  j
        !zone.  Polyvinyl chloride (PVC), hypalon,  and  other  types of membrane      j
        .sheeting C>20-mil)  also prevent gas migration  (Matrecon,  1980).   Special   j
        ^installation requirements are illustrated  in Figure  3.                      j
                                         VEGETATION
1 "^"^^ COVER SOIL ^^X^^x,
i
SAND
SAND N
                                                          YNTHETIC MEMBRANE
                       Figure  3.
  SEGiN

  OF TEXT
                                Gas protection scheme using synthetic membrane
                                covering large areas-over former refuse fill.
                                                                                      i BOTTC
                                                                                    ., FORT
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                  .'C.n.i

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        .—The sand  layers  above  and below  the membranes  provide physical protection —j
        I  during  installation.   Bentonite  has also  been  effectively used to prevent  I
CHOPPED j  gas migration  into  tree  and  grass  root  zones.   The trees and grass pictured
-E.--.D,   i  in Figure 4 were growing in  75 cm  of  soil spread over a 3-cm-thick bentonite
~V:,~:M   i  ]_ayer that was applied by hand over a rolled 15 cm clay base.  Note the    j
       Si—poor grass growth around the mound where  there was no gas barrier.  At  	i
       ;r!l_least^0._cnu.o.f._soil .shouldJae ..spread .over..these -barriers_to insure~.	_]
        ;  adequate  tree  growth.               <                                       I
        ;                i                      !                                       i
        i       The  trench  barrier  system (a  modification of the mound system)  may be
        ;  useful  if soil mounds  are not desirable in a particular area.  Although
        j  this system  (Figure 5) has been  successful on  a small scale (3 x 4 m) ,
        j  (Leone, et al.,  1979)  it would be  preferable to secure a barrier all the
          way to  the soil  surface  and  avoid  leaving a portion of the cover soil exr
         posed to the waste material and the entry  of laterally migrating gases.
                        i                      1
               Another method that may be  suitable  for planting trees and shrubs
          in small  areas such as planting  islands in parking lots involved the
         ^construction of  a saucer lined with one of the impermeable polymeric
        a*3^£.  	 	  		. 	   .  —  ——   ..  — .  .. -.	  	   	     - .t — .  -	*.,*—	-^_ __
        |  materials previously mentioned and drained by  an open U-tube installed at
          the bottom of  the saucer (Figure 6).{ The U-tube would allow accumulated
          water to  drain from the  bottom and prevent gases from back-flushing into
          the saucer.   <                      j
                     3-1/8"                   !
               Proper  functioning  of all the gas-barrier techniques mentioned
          depends on the assumption that the gas  barrier remains intact.  Since
          refuse  decomposition is  likely to  continue for scores of years, refuse
          settlement is  also  likely to continue for a similar time.  Cracks or
          breaks  in the  barrier  resulting  from  such settlement may also permit gas
          to migrate into  previously uncontaminated areas, and areas that contain
          gas may become free from gas.       j

          STEP B-4. SELECTING COVER SOIL
                        j
               Many landfill  operators cannot afford the luxury of selecting
          from a  variety of final  cover soils because of their high cost or lack
          of availability. Consequently,  many  revegetation attempts have failed.
          Methods of selecting and spreading the  first lajers of soil over the final
          refuse  layers  have  been  examined (Lutton, 1980), but the final layers
          of cover  soil  should be  selected according to  the criteria outlined below.

               The  first task in selecting cover  soil is to determine what kinds
          of soil are  available.  One, two,  or  more types of soil may be immediately
          transportable  to the site.   The  soil  with a texture closest to a loam
          should  be selected  for areas where trees  and  shrubs will be planted,
          because they generally require a looser,  deeper soil for root development
          than do the  grasses and  ground  covers.  This  soil  should then be tested
        I  for the constituents listed  in  Step A-3.   Five composite samples-con-
        |  sisting of five  subsamples  each  (Step A-4) should be collected and  sent
        I  to a certified soil testing  laboratory  if the  soil appears to be uniform.
        t~~More  samples will be necessary  if  a variety of soils are to be used for
                                                                                      GUTS!
    Lirut
:? TEXT
                                                                                    •-3*»,'
          CPA-2S7 iCiti.i
          ,4-76;

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f D{~' '*OCP,
LiriOi i -~
'-i~ \T]
                                    Good tree and grass growth  in 75-cm soil mound
                                    over a 3-cm thick layer  of  bentonite.
                                                           Tre
          60
cm Cover
 Soil
               Refuse
                                          90 cm Loamy Sand

                                          30 cm;Sand or
                                            Round Gravel
                                   20-mil synthetic  membran
                                                           10 cm Diameter  ;
                                                            PVC "-Vent Pipes  sQTTC
BSGiN
LAoT Li
            .Figure 5.  Gas  prevention scheme for small planters.  Vent
            i           pipes  should be spaced no more than 2 m apart.
 IMAGE
 OUTS!
{ DIME:
I rCR T
             § 3/3"
            I
            1
                                                                                        : TRAY,

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DROPPED
MEAD,
H£R£   -z
         20-mil Polymeric
             Liner     i

             Soil Base
5EG1N
LAbT •_
 r 75/
                                                                 Curb
                                                                 Parking Surface
                                                                 Demolition Base
Refuse
                                                             10 cm.  Diameter PVC
                                                               Vent  Pipes
                              ^d  Water Level in Trap
                                         Refuse
                       Figure 6.   Gas protection scheme for vegetation planting
                                  island  in a paved parking lot located over  a
                                  former  refuse landfill.  .
_i_:	i_	
                                          ':  18
              i T'ATiC
           4-7SJ

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DRG--ED !
HEAD.   !
   cover.  This decision should be made by a qualified soil scientist, because
   it is likely to be different for each site.  The soil should be tested
   before it is sent to the site, because of the relative ease of amending
   the soil before or during spreading.
^	STEP B-5.  SPREADING COVER SOIL.
        The clay soil layers should be spread over the final refuse layers
   to prevent infiltration into the landfill according to recommendations
   in "Evaluating Cover Systems for Solid and Hazardous Waste"  (Lutton,
   1980).  Since this soil will not adequately support vegetation, additional
   soil should be spread in the manner described below.
                ||
        One of the most critical steps in reclamation projects  is the actual
   placement of cover soil.  Earthscrapers are usually used for this task,
   and the end product is a series of horizontal layers of more or less loose
   soil, with vertically and horizontally adjacent compacted zones.  Bulk
   densities on the order of 2.0 g/cm3 in the wheelings of earthscrapers are
     iamon .w.ith .1..2_g/cm^2in.the. loosely ..spread, soil-between -the-wheels.™ The,~
   compacted zones have been shown to restrict root growth and  downward
   movement of soil moisture and may contribute to surface-water ponding.      j
   Soils that compact most easily include those of clay texture, those low     j
   in organic matter  (e.g., subsoils), and any soils that are wet during       j
   spreading. 9-1/3"                    j                                        j
                1                      i                                        i
        The avoidance or elimination of these compacted layers  can be a key    j
   to a successful reclamation project.  They can be avoided by mixing organic
   matter with the soil before it is spread, spreading soil only when it is    j
   dry, and by using earth-moving machinery other than the normal earthscraper.
   Dragline excavators, bucket-wheel excavators, forward-acting shovels, and
   bulldozers have been proposed, but may result in considerably higher
   operating costs than earthscrapers (McRae, 1979).                           ]
                1                      I                                        i
        If several  different soils will be used in the final 60 to 90 cm of   j
   cover material spread over the gas/water barrier, they should be mixed
   together and spread as a unit, not in separate layers.  Spreading soil
   in a thick layer will promote les-s^orer-all compaction, increased water
   movement, and better root growth than spreading in several thin layers.
                I                   '   M
        If soil must be spread in a conventional manner and bulk densities
   are above 1.7.to 1.8 g/cm , consider several procedures currently available'
   that will promote better root growth and soil water flow and ultimately     j
   provide a more successful reclamation project.                              j
                 I                      !,
        The destruction of the compacted layers by means of subsoiling or
   deep-tine ripping  after the full thickness  of soil cover has been placed
   will encourage better root growth, but it is not usually completely
 i  effective.  The available machinery most often cannot draw the  tines  deeply
 j  enough or sufficiently close together; or the operation is quite often
 •	performed at the wrong soil moisture  (i.e., too high)  (McRae, 1979).    , 	
       •5 Q
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rtr-se
'"-—Some success has been achieved with ripping each layer after it is spread —.
:   and with the use of specially designed subsoiler such as a vibrating       ;
   subsoiler or the double-digger.  This modified equipment may be used to    \
   incorporate the organic matter into the deeper soil layers.  Organic matter
   should preferably be mixed with the cover before it is spread.             !
                i                   "    i                                       !
                i              .         '                                       .
       J)rganic_ amendments areJbeneficial to the physic^l^_.chemicaJL,._and_
          biological properties of most cover soil.  Addition of organic materials
          decreases bulk density and increases water infiltration and retention.
          Some organic materials provide an energy source and improve the environ-
          ment for beneficial soil microorganisms.  These materials include humus,
          peat moss, manure, crop residues, food wastes, logging wastes, industrial
          organics, leaf compost, composted sewage sludge,  or refuse compost.  A
          soil bulk density of 1.2 to 1.4 g/cc is desirable depending on soil  texture.
          A higher density can generally be tolerated in a coarser soil.  Gypsum,
          perlite, or vermiculite may also be 'disced or chiseled into the existing
          soil.  These materials should also be incorporated into as deep a soil
          layer as possible, preferably at the time the cover soil is originally
        ^US-
           pread on the, landf ill,.or_o_n_ thejgas/liquid barrier._
 ."': rrvr  .<-•
               Soil structure can also be improved by  establishing  a  grass  or  ground
          cover for several years before planting trees and  shrubs.   The processes
          of freezing and  thawing, rainfall, earthworm and insect activity,  perco-
          lation, and leaching will  also help  increase soil  porosity  and promote
          more desirable physical properties.  'This process  of  reestablishing  the
          network" of soil  pores and  fissures that provide adequate  air  exchange with
          the atmosphere may take many years.
           STEP B-6.  SOIL DEPTH
                        1
               It has been  reported  (Bohm, 1979)  that  60%  to  80%  of tree root volume
           in  the forest  can be found in  the  top  20  cm  of mineral  soil and that most  |
           of  the fine feeder  roots are in  the  top several  centimeters.   Roots are    i
           likely to be  somewhat  deeper in  open plantings such as  parks and golf      !
           courses than  in the forest situation.   The remaining portion of the root   j
           system is located at varying depths  (from 20 to  90  cm), depending on       |
           species and soil  characteristics.  Thus a 30-cm  soil may normally accommod-
           ate a good portion  of  root volume; but on a  landfill, this shallow soil    j
           would dry out.very  quickly during  seasonal drought  spells and would not    |
           adequately support  large trees.

               Because  of the excessive  cost of  covering  the  entire landfill with
           deep, rich soil,  the planner should  consider spreading 90 cm only in
           those areas where trees are to be  planted.  This layer need not be made
           up  entirely of topsoil, but the  depth  at  which most of the feeder roots
           will be  growing  (20 cm) should be  topsoil.,  At  least 60 cm of soil should
           be  spread  in  areas  where  trees will  not be planted.  The depth of cover
           soil  should allow enough  space for grasses and  other stabilizing vegetation
           to  develop an adequate root system,  provided landfill gases are not present
           in  the  cover  soil.                   I
                                                                                2GTTO
                                                                                 '-'AGE
                                                                                CiMEN
                                                                                FOR T-
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                                                                                TRATK

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I-
            —STEP B-7.  LOCATING AREAS UNSUITED FOR TREE AND SHRUB GROWTH
           i     '           i                       ;
           ;        Areas unsuited for tree and shrub growth can be located either
           \   before or after selecting specific sites for tree and shrub planting.
           ;   Possible indicators of a potentially poor growth site include dead or
                 vegetation,  anaerobic soil, high soil temperatures, thin cover soil.
 Areas  with Dead  or  No Vegetation    i
          •    i                      i
     The simplest method for  locating unsuitable areas  for trees  and
 shrubs is to  observe existing vegetation patterns.   Areas where soil
 appears thin  will most likely have very little or no plant growth
 (Figure 7).   The C02 and CH^  concentrations  in these soil atmospheres
 are  likely to be high and limiting to plant  establishment.  Soil  temper-
 atures are frequently elevated in these so called "hot  spots",  ranging
 anywhere from! a  degree or two to  more than 20°C above surrounding un-
 contaminated  soil.   Such barren areas should be avoided when selecting
 sites. for_j:rees_and, shrubs.	j	,	
              I                      I
 Anaerobic Soils                     j
              1                      '                                       i
     Anaerobic soil conditions may not occur until  after plants have been :
 growing for some time.  Vegetation will die  if the  soil becomes contaminated
 with the gases of   anaerobic  decomposition.   If plants  of different  species
 in an  area are dead,  dying, or nonexistent,  chances are that the  soil has ]
 been contaminated with gas and that this area is poorly suited  for growing
 plants of any kind.   If plants of only one species  appear to be affected,
 one  should have  a qualified plant pathologist or county agricultural
 agent  evaluate the  problem, as there  may be  a disease or insect problem.
 Some of the following  -.tests  may  be performed to check  for anaerobic soil
 conditions.   ,                      i
           !
Direct Gas Measurement—            '•                                        \
     Direct measurements of ^combustible gases can be made in the root zone  i
of an area where one wishes to plant.   A gas sample is drawn from the soil  j
through a holev made with a barhole-maker,to an explosimeter (the type of    1
instrument frequently used by the utility companies when looking for leaks  j
in their underground gas lines).  Readings taken from the 30-, 60- and 90-  j
cm depths generally present an accurate picture of the amount of gas in the,
cover soil.  Planting is not recommended if any combustible gases are       j
present in the cover soil.  If gas is not extracted from the landfill and   j
no clay or other barrier exists over the refuse, then portions of the soil  j
cover will most likely become contaminated.
              I                      1
     The carbon dioxide and oxygen contents of the root zone should also
           |  be measured.  Soil gas samples can be taken from bar holes with Bacharach
           i  Fyrite or other carbon dioxide and oxygen indicators.  High carbon dioxide
           :  concentrations are sometimes found in landfill soils despite  the  absence
                                                                             2CTTC
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                                                                                             1V! :.' '•'' O
                                                                                                     in
                                                                                                     O
              Figure 7.  Area with shallow cover soil and consequently little or no plant growth
.^.-L—
r"" ?' I'J "j f- ^ O
j> Q uj ^ IH > -H
                                                                                              J	1

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  HEA
C
  55
  -of combustible gases.  The high carbon dioxide  content  is  toxic  to plants —
  and indicates the possibility that soils may be anaerobic  at  times.   In
  fact, current scientific evidence indicates that carbon dioxide  is probably
  more toxic to vegetation than methare. (Arthur et al.,  1981).  Root
  growth of some plant species is inhibited when  soil oxygen content decreases
  _to 10%.  Other species are not adversely affected by  02 concentrations as_
  low as 1% (Flpw^r_ej:^l^,_]JJ8^.__^he_Jtog
                            _
           "low oxygen concentrations are often highly correlated with each other.

                 Though an area may have been chosen for planting as a result of low
            combustible gas readings, differential settlement and varying gas production
            rates may saturate an area that was once free of landfill gases; the reverse
            may also occur.
                         i
            Physical Characteristics —
                 The soil. itself should be examined to detect anaerobic conditions.
            In many cases,  unpleasant odors of anaerobic decomposition are quite
            noticeable in ] soils that are lacking in oxygen.  Such soil is generally
j  darker, damper, and more_clay-like_ (less_ friable)_ thj^J           -™ __ .3
r*^Erob"ic~condition. J"lAerobTc~s6ils~that  do not  contain measurable landfill
  gases  do not  tend  to  accumulate  as  much moisture as anaerobic soils.
                !                       I
 Tests for Ammonium-nitrogen, Manganese and Iron —
       Soil  tests will  also  generally reveal higher amounts of ammonium-
  nitrogen  (NH^-N) and  available manganese (Mn)  in anaerobic than in
  aerobic" soils.  The available iron  (Fe)  and zinc (Zn) content may also be
  considerably  higher in  soils that  have been anaerobic for an extended
  period of  time.

 H igh_Soil Temperatures
 -            : ~                      i
       Temperatures  in  anaerobic soils 'are frequently higher than in nearby
  aerobic soil—from a  degree or two  to perhaps  20° or 30°C in extreme cases.;
  The reason for these  high  soil temperatures is undetermined, but it may
  result from microbial activity,  chemical reactions, and/or underground
  fires.       !
 Thin Soil Cover

      The amount and quality of soil covering the refuse in a landfill
 has frequently been found to be inadequate for vegetation growth.
 Measures for correcting these deficiencies are outlined in Steps A-2,
 A-4, A-6, B-4:and B-6.

 Settled Areas
              i
      Refuse and soil settlement caused by loss of solid refuse material
 through biological and chemical decomposition will create an undulating
 surface that causes water to accumulate in low areas during periods of
 rain and irrigation.  Trees, shrubs,:and grass in flooded areas may
 eventually die if water remains for extended periods and/or if rainfall
-is frequent. !Furthermore, undulating greens will not be tolerated in
           	  '	 	 	     - -	-j- | - -         	j_.ii.-_	 _u V- -i IV i j-. - --	--J—i	 .: -------  	
   -3 3/8"      w                 -m:--'23" :-;•'•
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 h=AD,
     :NS
  -most golf courses.   Operation of farm equipment may also be hindered by
   uneven surfaces.  Provisions should therefore be made to accommodate
   settlement.   In extremely dry climates,  on the other hand,  plant growth
   may be enhanced in  the settled areas because of increased soil moisture.
                ;                   .   i
	.STEP B-8.  SELECTING TREE AND SHRUB MATERIAL
SEuhM
                The  end  use  for  the  completed  landfill  must  be known before plant
           species are selected.   The  desired  species for  a  nature area may be
           different from those  selected  for a park or  golf  course.   Once an end use
           has been  selected and the general type  of vegetation has been determined,
           the following guidelines  will  be useful.
                        I                       I
                The  first consideration should be  the great  variation in species that
           grow  in widely separated  geographic areas on this continent.   Choices
           should be limited to  plants that are known to be  adaptable to the areas
           and that  will be  commercially  available there.
,    __   ^ sjecond_consideration  shojuld  be_that jrefuse_quaJLity, _quantity,  age,
\ " and  depth differ markedly  from landfill  to  landfril~and™from"one" geographic"
]   area to  another.   For instance, a  former open-burning  dump  may generate    \
i   little landfill gas  and  undergo only  minor  settlement  because  it contains  i
\   only small amounts of biodegradable organics.  Variations in climate are   |
\   also represented across  North  America.   These  factors  and others interact  }
   to produce widely  different  environmental stresses  as  well  as  varying gas  !
   production rates and mixtures.      I
                i                      i
       The third item  to consider is that  field  data  indicate that when the
   combustible gas and/or carbon  dioxide concentrations are excessive and
   the  soil is anaerobic, few if  any  tree species are  able to  survive.
                i                      i
       Despite these limitations, research results  have  indicated that trees
   and  shrubs grown successfully  on completed  landfill sites have a variety
   of common characteristics  (Flower  et  al. , 1981, Oilman et al., 1981).
               .i              _        !
       Factors to be considered  in choosing the  tree  species  to  be planted
   include  growth rate,  tree  size, rooting  depth, flood tolerance, mycorrhi-
   zal  fungi and pathological considerations.  A  discussion of these factors
   follows .      i

   Slow-Growing vs. Rapid-Growing Species
                I                      i
       Evidence ! indicates  that slow-growing trees are more tolerant to land-
   fill conditions than rapid-growing species.  The  faster-growing trees      i
   generally draw more  moisture from  the soil  and would therefore require      i
   more irrigation to maintain  growth comparable  with  their growth on a non-
   landfill area.  But,  if  comparison with non-landfill  areas is not a
   concern,  a faster- growing  tree may be more  desirable with its  more quickly
   produced vegetative  cover.   Species classified as fast growers produce
   more total growth  on a landfill than  the slow  growers  if they  are regularly
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          -irrigated during the first 3 years after planting.  Table 4 lists some of"
          the slow moderate- and rapid- growing tree species found in the United
cao;:?SO | States. | • |
HEAD,
BEGIN
i 1
TABLE 4. SOME SLOW, MODERATE AND
SECTIONS 	 ! FOUND IN THE
A|^ -r - - 	 ----- 	 	


RAPID GROWING TREE SPECIES
UNITED STATES
- 	 	



	 ,
	 .
          Slow
                                      Moderate
       Rapid
          Serviceberry '
          Sargent cherry
          European hornbeam
          Yellow-wood  '
          Ginkgo       j
          Flowering dogwood
           	!  	 6-1/2"	
                             Littleleaf European linden
                             European white birch
                             October Glory red maple
                             Kentucky coffee-tree
                             Hackberry    j
                             Kwanzan Japanese flowering
                               cherry
                                             T
 Summershade Norway
   maple
 Shademaster thornless
   honey locust
 Sawtooth oak
 Hybrid poplar
 Willow oak
-Tree-of-heaven- —as
 Silver linden
-.EC:'
LAST
                 -*— t t i"*
      More complete lists are available in Pirone (1978) and Fowells  (1965), or
      at the county agricultural agent's office.
                    1                      j
      Small versus Large Plant Material   I
                    i                      I
           Results of limited investigations indicate  that trees planted when
      small ( 1 m-tall) show significantly better growth on landfills than  do
      those of the same species planted when taller than 2 m, regardless of
      species.  This phenomenon is related to the ability of a  small  tree to
      adapt its root system to the adverse environment in the cover soil by
      producing roots close to the surface (i.e., away fvom the high  landfill
      gas concentrations that occur deeper in the soil).  Roots of larger trees,
      on the other hand, start much deeper and  sometimes cannot produce much
      growth toward^the surface before being killed by landfill gases.  In  fact,
      by the time the larger tree adjusts to the landfill by attempting to
      produce a shallow root system, the smaller specimens, which started with
      a shallow root system, may actually equal or surpass the  larger trees.
      If it is necessary to plant trees taller  than 1.5 m, plant them on a
      raised bed to'provide an adequate depth of soil  uncontaminated  by land-
      fill gas to accomodate roots already developed in non-landfill  soil.
      Larger plant material can be used only if landfill gas is kept  from the
      root system and the plants are well irrigated.

                                          !                            ,  •
      Volunteer Species                   <
    j                !                      i
'   J       Although volunteer tree species  (early" successional  species) have not
.~lTEj	been specifically studied on landfills, they are generally, very adaptable—
                      HOTTC
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                      wO ! Ol
                      OiMEN
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3EG!;\
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          -to poor  soil  conditions  and  are often the best species for establishing 	;
          trees in a low public-use  area  of  a landfill.   Volunteer species indigenous
          to several areas of  the  country are given in Table 5.                      <
               TABLE 5.
VOLUNTEER (PIONEER) TREE SPECIES INDIGENOUS  TO  VARIOUS
     GEOGRAPHIC AREAS OF THE UNITED  STATES
          Southeast     '
                        1
          Mimosa        i
          Eastern  cottonwood
          Sweetgum     j
          Red stemmed  dogwood
          Loblolly pine'
          Eastern  red  cedar
          Sumac         i
          Boxelder     '
            	, _	j. _ 6-1/2'
          Northeast     j

          Gray birch   '
          Mulberry     !
          Paulownia  9-1/3"
          Catalpa-      i
          Eastern  red  cedar
          Red stemmed  dogwood
          Red maple     '
          Bayberry     j
          Quaking  aspen
          Hybrid poplar
          Sumac         j
          Boxelder     ]
          Black locust !
                                                 Northeast-Great Lakes

                                                 Jack pine
                                                 Quaking aspen
                                                 Pin cherry
                                                 Red stemmed  dogwood
                                                 Paper birch
                                                 Boxelder

                                                 Plains States

                                                 Choke cherry
                                                 Boxelder
                                                 Red stemmed  dogwood
                                                 Black locust

                                                 Northwest

                                                 Red alder
                                                 Red stemmed  dogwood
                                                 Quaking  aspen
                                                 Boxelder

                                                 Appalachia

                                                 Black locust
                                                 Boxelder
                                                 Red  stemmed  dogwood

                                                 Puerto  Rico

                                                 Mimosa
                                                 Acacia
                                                 West-Indian locust
                                                 Hollywood
                                                 Dominican mahogany
                                                 Lignum vitae
0cr;;N
LAST LINE)
0" 'EXT- -'S|br
           Additional information on volunteer  species" can be found in Harlow and
           Harrar, 1969.,                                         ,   .
                                          -.:=.•••;.' 26
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          •—Natural Rooting Depth
                 Tree and shrub species that enjoy shallow  root  systems were found to
            be significantly more adapted to landfill sites than species  requiring
            a much deeper root system  (Table 6).;
                 _TABL.E_6J___VERTI.CAL_DISTRIBUTIQN jpFJIREE^RQOTS_.IN .LANDFILL .AND.
                          '             NON-LANDFILL SOIL
            Species
                                                      Average Depth  (cm)
                               On Landfill
 Off Landfill
          i  Japanese black pine
          1  Norway spruce
          !  Hybrid poplar cuttings
          UsaHoney- locust—I — 6-1/2"
            Green ash     ]
            Hybrid poplar!saplings
                                   7!
                                   5''
                                   6
                                   8'-
                                   9
                                   9
       9
       4
      13
	1-7
      15
      13
c
           9-1/3"                    I
aSpecies at top of list were more adapted to the landfill than those
 at the bottom (Gilman, et al, 1981).

The deeper roots are subjected to higher concentrations of landfill gases
and lower concentrations of 02-  Some species can avoid this adverse gas
environment by producing a shallow root system.  Observations at the South  ;
Coast Botanical Garden in Palos Verdes, California  (a former 87-acre land-  j
fill site) showed that shallow-rooted plants are seldom affected by landfill
gases; in some cases, however, root damage has occurred in the larger  trees
and shrubs (Flower et al., 1978).  Several texts are readily available     I
showing the natural rooting depth of woody species  (Fowells, 1965; Harlow   j
and Harrar, 1969), however these lists are incomplete.
                                    i

     The fact | that trees growing on landfills generally develop .shallower
roots than the same species growing off the landfill emphasizes the need
for frequent irrigation of landfill soils planted with woody vegetation—
especially if gas is not extracted from the refuse.  If landfill gas is
kept out of the cover soil, roots should be able to grow deeper.  Species
excavated for extensive root studies on landfills had a significantly
larger portion of their root system in the top soil layers (Figure 8)
than in the deeper layers.  But, roots were much more evenly distributed
depthwise on trees growing in the nearby non-landfill control area  .
(Figure 9).   j                      i                            :.
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                                                27
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                        Eigure  8.   Excavated green ash on landfill showing most  roots in top soil layejr
                                                                                                               1	J'!
       : t > p.i o O ;; ™
       ,JJ ", C.' r- r" > u
       ,t^ P! U) :' -J > -t
         °         -

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   4 PC-    -
c
   3EGIM
   LAST LINEi
   OF TEXT
C
                      Figure 9.   Excavated green ash in control area showing  even
                            |      distribution depthwise of root system.
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                                               :•.-•...  29  ••••:>
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oEGINi
SEC';"';
HERE
        ,	Because many roots are found growing close to the surface and since the 	i
        !   top several centimeters of soil regularly dry out for extended periods     ]
DROPPED ;   in the temperate zone of North America, landfill soils must be irrigated   i
           more frequently than nearby non-landfill areas to ensure good vegetation
           growth.  Also,  our field studies indicate that landfill cover-soils do
          _not maintain as high a moisture content as the same soils off the land- 	1
          _fill.	This ._may.J>e_due.__tQ_a._lac.k. of ,,ve,r .t ical_upwaK.d_transport_Qf_jpaQi.st.ur^	j
           through the refuse and greater evapotranspiration on the landfill.          1
                        i                       j
               Lysimeter  studies have shown that plant roots can penetrate into
           refuse zones,' but these studies fail to report on the gaseous conditions
           in the refuse.   More than likely, the refuse was not in an anaerobic
           state, since most plant roots soon succumb in such environments.  Few
           roots  on the one landfill studied ever grew deeper than 20 cm.  Those
           that were deeper always died before reaching the refuse—probably from
           the lack of oxygen in areas close to the refuse.
                        !                       I
                It is difficult to know whether tree roots will penetrate a synthetic
          ^membrane j>laced_pver .^he_refus_e as a_gas andJLiquid_barrie_r.	 If jthe__seal  '
          'remains intact  (i.e.,"if settlement does not disturb the integrity of the  j
           membrane), and  if landfill gas is kept from the soil above the seal, then  j
           roots  may penetrate 1 m of soil and grow to the membrane.  Root growth     j
           may continue if water has drained away from this point.  The propensity
           for roots to attempt to penetrate this layer would be species-dependent
           (i.e.,"the shallower rooted species are not as likely to penetrate the
           membrane as the more deeply rooted trees).  Also a factor is the extreme
           force  required  to penetrate a 20-mil PVC membrane.  Research in this area
           is lacking, so  no definite answers exist presently.  Techniques such as
           surface fertilizing (as opposed to fertilizing at depth, the standard
           procedure for- tree fertilization) and frequent light irrigation will
           promote shallow-rootedness.  Since the roots will be shallow, irrigation
           will be required to maintain the trees and shrubs on such an area.
                        i                       i
                The root systems of grasses are generally much shallower than tree
           roots, so these roots should not penetrate gas/liquid barriers if at
           least  60 cm of  cover is present above the barrier.

           Flood  Tolerance

             __~~ Our field  data indicate that the changes produced by landfill gases
           in the cover soils are similar to those imposed by the flooding of soils;
           the difference  is that the high moisture content is lacking on a landfill.
           Thus species that are resistant to wet feet (flooding conditions) may do
           well on landfills only if they are supplied with adequate water.  Dry-site I
           species should  be planted if water will not be readily available
          Size of Plants at Maturity
               Another factor to consider when  selecting  species  for landfills is
          size of the tree at maturity.  If the only  cover  soil available for root
        	growth is relatively shallow  (30 to 60  cm), a tree  should be chosen that
                                                                                       30TTC
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                                              30

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   DROPPED
   HuAD;
   BEGIN
'C
'—-  remains  relatively  small  at maturity;  otherwise there is a risk that the—
    tree will topple  during high-volocity  winds.   If a deeper soil cover
    (>1  m) is available to the roots,  the  risk of  windthrow will be dimin-
    ished  because  the root systems  has adequate soil space to produce anchor
    roots  (provided landfill  gases  are kept  out of the cover soil and the
	  trees  are irrigated).  A  number of publications contain information on	
    tree height  aj^maturity (^owells,._!965_;_Pirone, 1978)).	Th_e__c_ounty_	
    agricultural agent, local nurseries, and landscape architects can
    provide  information for a particular locale.   Some of the smaller trees
    and  shrubs are listed in  Table  7.
               i
               *
        TABLE 7.  SOME SMALL TREES AND SHRUBS (LESS THAN 9m TALL
               i                  AT MATURITY)
                     Common.Name
                                                Latin Name
           ;«*
    Upright  European^hornbeam
   -Servic'eberry ~~  5-1/2"
    Hawthorn   |
    Goldentrain tree
    Flowering  dogwood
    Kwanzan  cherry
    Black chokecherry
   Common chokecherry
   American elder
   Sawtooth oak
   Osage-orange
   •Crabapple
   Virginia pine
   Eastern red cedar
                                              Carpinus betulus f. fastigiata
                                              'Amelanchier spp.
                                              Crataegus spp.
                                              Voelreuteria paniculata
                                              Cornus florida
                                              Prunus serrula'ta 'Kwanzan'
                                              Aronia melanocarpa
                                              Prunus virginiana
                                              Sambucus canadensis
                                                  Quercus  acutissima
                                                  Maclura  pomifera
                                                  Malus spp
                                                  Pinus virginiana
                                                  Juniperus virginiana

OCUi
  ;n    '•
Cr TEXT 3
               Trees  that  are  small  at maturity  should be  chosen if cover soils are
               shallow,  if ;gas is  not extracted  from the fill,  or if a gas barrier
               is not installed.                  !
                           I
               Mycorrhizal Fungi

                    Mycorrhizal fungi in association with  plant roots have been shown
               to greatly  increase water and  nutrient uptake by the plants.  This
               symbiotic association has been successfully used in reclamation of coal
               strip  mines.  Mycorrhizae may  also aid in successfully establishing
               vegetation  on completed dump sites,  since landfill cover soil frequently
               has  a  poor  capacity for holding nutrients and water.  Spore- and
               mycelium-inoculated soil  has been tested for its ability to promote
               mycelium development  on trees  in  landfill cover  soil (Telson, Leone,     |
               and  Flower, 1980 personal communication).   Results of limited experiments
               indicate that both  forms  of inoculation may be viable alternatives to    j
                                                                              30TTC
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planting trees in un-inoculated  soil; however, the spore inoculum appears
to be more suited to areas of higher gas content.  The roots may be      j
inoculated directly just before planting to increase the likelihood      }
of successfully establishing the beneficial mycorrhizal relationship.
            ;                      i
Pathological Considerations       i                                     _
                 The selection of trees,  shrubs or grasses should always be based on
            their ability to withstand attack by damaging diseases or insects common
            to the given area.  The county agricultural agent or soil conservation
            service should be contacted,  as they can frequently provide valuable
            practical information concerning disease and insect-resistant plant
            material, optimum planting time, proper fertilization, and other
            amendments critical to an insect and disease control program.
                        i                       !
            STEP B-9.  PLANTING AND MAINTAINING VEGETATION
                        i                       J
                 Trees and shrubs survive best'if planted in early spring or fall.
            The Extension Service, or Soil Conservation  Service can ^identify_which_
            ~plantlng'~time~Ts "best for~a "ipecific area and species.  Do not plant
            during the summer.  Plants purchased from a nursery and delivered to the
            site should be planted as soon as possible.  Bare-rooted material can
            dry out in a matter of hours  if left in the sun.  Balled and burlapped
            material can be left for some time longer,  but it must be irrigated       j
            within a day or two, depending on the weather conditions.  One person
            should not be scheduled to plant too many trees in one day.  Schedule
            the work load so that only the trees that can be planted in a day
            are present on the site.  In the long run,  it may be more desirable
            to schedule a pick-up or delivery of plants each day, if practical.  If
            all the trees must be delivered on the same day, arrangements should
            be made for storing the plants in a shaded, preferably cool, indoor
            environment free from wind.  Regardless of how the plants are stored or
            how soon after delivery they are put into the ground, an irrigation truck
            or other water-supplying vehicle should be made available to deliver      j
            several gallons of water to each tree at the time of planting.
                       -j              ^        j
                 A planting hole about twice as wide as the root mass diameter and
            up to 15 cm deeper than the deepest root is well suited for trees and
            shrubs.  Care should be taken to avoid compacting the sides of the
            planting hole; such a step might promote prolific root growth inside
            the original hole but inhibit root 'penetration into the surrounding
            soil.

                 Mix some of the original cover soil with some loamy textured material
            (preferably a highly organic soil) and spread enough of it in the bottom  •:
            of the hole to make a 15-cm deep layer  (50:50 mixture would be a          \
            desirable combination).  Hold the main stem of the tree or shrub and      |
            fill in around the root system until the hole is half filled.  'Gently     I 30T70
            press the soil down with the sole  of your  shoe; do not pack  it down.      i IMAGE
                                               i                                        GUTS! i
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         ~T—During the backfilling process, be sure to relocate the roots so that their
         I   depth is equal to their original depth in the nursery.  The latter can
         ;   usually be determined by letting the roots hang freely before planting.
         i   Do not compact all the roots at the bottom of the hole.  Spread them out
         I   as much as possible.  At this point, the soil should be watered so that the
         ;	entire root system has been moistened.  This step may take one to several
         •fs~ gallons, depending on tree size.  When the water has all soaked into the
                 '~"~
C
         fill the rest  of the hole with the  soil  mix and gently press the
   soil down with your  foot.   Form a  ridge around the stem with an inside
   diameter about equal to the extent of the root system and fill this well
   with water.   These simple  procedures will retain all possible moisture
   from rainfall and irrigation and help trees  survive through the most
   critical first season.  Mulching with wood chips,  bark, sawdust, grass
   clippings, plant debris, or many other materials can help control water
   loss by reducing weed growth and evaporation from the soil surface around
   the trees.   i                       i

        The principles  set forth above for planting small, bare-rooted trees
i   generally hold for planting older, larger balled-and-burlapped^specimens.
h*1Tfe~do~h"ot~reconmend  planting" trees older  than~2 "to ~3~ years", "6V taller" than" ;
j   1 to 1.5 m with root systems 15 cm or more below the soil surface unless
!   specific provisions  for preventing gas migration into the root zone have
!   been implemented and the soil is at least 90 cm deep.  If it is impossible
!   to obtain small seedlings  for planting, several additional provisions are
i   necessary for,the larger trees. First, more water will be required at the
I   time of planting and during subsequent irrigation periods to saturate the
   soil around the root system.  Second, each of the trees must be supported
   with at leas t^ two stakes and preferably three.
                !                       i
        The principles  of maintaining plant  material on completed landfill
   sites are no different from those  for non-landfill areas except that
   additional irrigation is required.  Soil  with a low nutrient status must
   be fertilized, and soils with the  wrong pH (below 5.5 and above 7.0) must
   be limed or acidified to desirable limits.  The pH and nutrient levels in
   the soils should be  tested periodically (every 2 to 3 years) after plant-
   ing.  Fall is the best season for  such testing so that any necessary
   soil application can be made in early spring.   The county agricultural
   agent and Step A-4 can provide information on proper soil sampling methods
   and interpretion of  the test results.
                i                       i
        Irrigation is an extremely important requirement for establishing and
   maintaining healthy plant  material on former sanitary landfills, particul-
   arly during the first 2 to 3 years after  planting.  After this time, roots
   may have established a large enough system to withstand moderate drought
   periods; however, irrigation should be practiced during extended hot,
   humid weather, even for large, established trees.  This additional watering
   is needed because of the shallow roots close to the landfill soil surface  |
   where there is little available soil moisture during extended dry periods. ;
   In-ground irrigation systems require continual repair, since settlement
   is likely to cause frequent breaks in the pipes and thus increase main-
    tenance costs.  Various above-ground, expandable joint irrigation systems —
    ire_available.	;	.	^	—
                                               33
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.—      Plants should be protected  from disease and insect infestations an3  i
    damaging animals.  Several animals  enjoy chewing the bark of certain      j
:    species during the winter.  Check with the county agricultural agent and  ;
>    nurserymen to see if the  selected species are susceptible to such attack. ;
•    Some species are particularly vulnerable to winter desiccation.  The      j
'	 county agent can recommend procedures for overcoming this problem.     	!
^  Excellent instructions.-for-tree .maintenance-are-provided by Pirone -(1978) .
     	j. _ 6-1/2'
                                        i
               9-1/3"
                                                                                 80TTO
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     .4-75)

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3F TEXT-.£
                                          SECTION 3
                                               i
                               LANDFILL CONVERSION: A HYPOTHETICAL CASE
                 This section uses a hypothetical example to illustrate the pro-
            cedures described in this manual for closing a landfill and converting
            it into a multiple-use recreational facility where adequate funds are
            available to. select from a variety of cover materials, gas barriers,
            and tree species.

            	For_this hypqthetical_landfill,_ a_landscape_ architectjrecommends
            that a larger variety of end uses be incorporated into the reclamation
            plan, including a nine-hole golf course,  botanical garden, toboggan run
            picnic area, | nature area, tree and shrub  nursery for replacing dead
            plants, bicycle paths, and campgrounds.
                      9-1/8"                    I
                 'Ideally, gases should either be extracted from within the landfill
            layers or the entire, landfill covered by  a gas barrier with passive
            gas vents.  The following suggests methods for developing the end use
            where neither a complete gas extraction system or gas-barrier was
            instituted.  (            .           !
                 Consider the type,  age,  and depth of refuse when choosing areas to
            locate the various recreational facilities.  Gas problems are likely to
            be somewhat less severe  in the older,  shallower, and least putrescible
            refuse areas, so they should  be chosen as sites for the botanical garden
            and nurseryJ  Any area receiving only demolition debris would be well
            suited for these uses.  If"putrescible materials are present (as is
            generally the case),  install  one of the gas barrier systems described
            in Step B-3 and spread a  high -quality soil above it.  If little or no
            putrescible material  was placed here,  then check for combustible gas
            at the 60-and 90-cm depths (see Step B-7) in 10 to 15 locations per acre,
            since gases can migrate  from  adjacent areas containing putrescibles and   j
            adversely affect vegetation.   If combustible gas readings are consistently.
            100% of the lower explosive limit or higher in concentration, a gas       j
            barrier should definitely be  installed (Step B-3) before additional soil
            is spread (Step B-5)  or  before trees and shrubs are planted (Step B-9).
            Cover material can be removed and stockpiled to give a total depth of
            90 cm in tree-growth  areas.  Trees should not be planted on a landfill
            without a gas-barrier, since  more than 50% of unshielded specimens may
            be killed during the  first year after planting.  An above-ground irrigation
            system should be installed so that every tree will be watered during the
           •growing season.                    i
            3 3/8"
            j	

           £.-A-2S7 JCiM.j
                        1
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HERE   2r
      The trees on the golf course can be planted in soil mounds under-"
 laid with a suitable gas barrier such as 20-mil PVC sheeting, a 30-cm-
 thick clay layer, or a 3-cm-thick layer of bentonite.  This method does
 not protect the grass in the fairways, however.  No remedy exists for
 this problem, and replanting will not help unless the gas later
 moves away from the area.  The course superintendent can check for this—<
_pccurrence._je.yery_Jl_.-or _2_.months._after,_the problem .arises.—If-the-problem ',
 persists, consider converting the area into a sand trap.  The course     j
 architect may even consider locating the sand traps 1 or 2 years after   j
 the fairways are established so that they can all be situated over areas
 of gas effusion where they will serve as passive gas vents.
            I                       i
      A system must be designed to accommodate settling beneath the
 greens, and perhaps the tees,, since these areas must remain flat.
 Reinforced concrete slabs can be installed under each green so that, as
 the ground settles, the green will move as a single unit and remain
 flat.  Unfortunately, it may not retain the same pitch.
            i                       I
	The_nature area can .be ..planted, withjaative..volunteer jtrees »_shrubs,.
 and grasses in a fashion simulating natural succession.  If barriers are
 not installed, the trees and shrubs should be planted as seeds or 1-year
 whips so that the root systems can adapt to the soil conditions.  A 90-
 cm cover of soil should be placed over the refuse, and the soil should be
 checked for'nutrients (Step A-4) and bulk density  (Step A-5).  Areas
 that do not,support plant growth can at least be used for educational
 purposes.  Such areas can dramatically demonstrate the effects of gas
 kill on vegetation.

                        i
                  The picnic areas,  tobaggon runs, and camp grounds should be seeded
             with grass and perhaps  other ground covers if desirable.  Species should
             be chosen that performed best in the experimental test grounds established
             several years earlier (Step A-3).  jBare spots where no vegetation grows
             because of soil gas contamination can be covered with stones or wood-
             chips to help control erosion and make the area presentable.  Trees can
             be planted .in groves if a gas barrier is placed 90 cm below the
             soil surface.

                  A perennial maintenance program must be instituted to keep this
             multiple-use facility operating effectively.  Dead trees must be removed
             and new ones must be planted.  Living trees must be fertilized, pruned,
             and treated(for insects and diseases.  Grasses must be maintained and
             the nursery,  botanical garden, and golf course will need special attention
             Erosion must be checked in bare areas that develop.  The soil surface
             must be maintained in areas of uneven settlement throughout the park,
             and the plants must be irrigated more frequently than those on off-
             landfill parks.  A reputable tree expert company, arborist, or land-
             scaper should be retained for professional services and recommendations
             throughout the life of the park.  \
 LAST Li^b
 OF TEXT
         I
                                              •' '-I-'
                                               36
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          4.
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          6.



          7.


          8.



          9.


         10.
       EJ
       -ll.
                                           REFERENCES
 Arthur, J.;J., I. A. Leone, and F. B. Flower.   Flooding and Landfill
 Gas Effects on Red and Sugar Maples.  J. of Environ.  Qual.  10:431-
 433, 1981.:
            1
 Bohm, W.  Methods of Studying Root Systems.  Springer-Verlag,
 Berlin-Heidelberg, 1979.  188 pp.i
            I                       1
 Chaney, R.!L.  Crop and Food Effects of Toxic  Elements  in Sludges and
-Effluents,-! -In: :-i.Prbceedings on Recycling -Municipal-Sludges-and-	2s*j
 Effluents on Land.  Nat. Assoc. State University  and  Land Grant Colleges,
 U.S. Environmental Protection Agency, and U.S.  Department of Agriculture
 Workshop,  iChampaign, Illinois, 1973.  pp. 129-141.                      j
            !                       !
 EmcoJi Associates.  Methane Generation and Recovery from Landfills.
 Ann Arbor Science, Michigan, 1980.[ 139 pp.
                                   i
 Flower, F. B., I. A. Leone, E. F.:Gilman, and  J.  J. Arthur. A Study
 of Vegetative Problems Associated with Refuse  Landfills.   EPA-600/2-
 78-094.  U.S. Environmental Protection Agency,  Cincinnati,  Ohio,1978.
 142 pp.    '                       j
            *  ,                     J
 Flower, F. B., E. F. Gilman, and  I. A. Leone.   Landfill Gas:   What It
 Does to trees and How Its Injurious Effects May be Prevented.   J. of
 Arboriculture, 7(2): 43-52, 1981. ;
           ~i              *         I
 Fowells, H. A.  Silvics of Forest Trees of the United States.   U.S.
 Department .of Agriculture.  Handbook No. 271,  1965.   762 pp.
            i                       |
 Gilman, E. |F., I. A. Leone, and F. B. Flower.   Critical Factors
 Controlling Vegetation Growth on Landfills.  EPA-600/2- 81-164,
 U.S. Environmental Protection Agency, Cincinnati, Ohio, 1981.   197 pp.
            i                       i
 Harlow, W. M. and E. S. Harrar.  Textbook of Dendrology.   McGraw-
 Hill, New York, 1969,512 pp.

 Leone, I. A., F. B. Flower, E. F.!Gilman, and  J.  J. Arthur. Adapting
 Woody Species and Planting Techniques to Landfill Conditions."- EPA
 600/2-79-128, U.S. Environmental Protection Agency, Cincinnati,  Ohio
 1979, 134  ipp.                    ;
                                                                                        JOTTC
                                                                                         MAGE
                                                                                        OUT SI
 Lutton, R. J.  Evaluating Cover Systems for Solid and Hazardous  Waste.
~SW-867r~U.~S ,~Environmental"Protect ion~Age~hl:yT~Cinric!fo^
1 " '       ?                 ••(/:•:•••: 37 ••'xix'::                                  \  '~?ATi
                                           'GE :V_:.U8ER

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 12.


13.
1
?J^
 147
|
J15.
1
\
J16.

u
Matrecon, Inc.  Lining of Waste Impoundment and Disposal  Facilties.   	1
SW-870.  U.S. Environmental Protection Agency, Cinncinnati,  Ohio*  385 pp.
1980.      -                       ,

McRae, S. G.  The Agricultural Restoration of Sand and Gravel
Quarries in Great Britain.  Reclamation Review.   2: 133-141, 1979.
             Pirone, P. P.  Tree Maintenance.  Oxford University Press,  New
             York, 1978.  587  pp.             i
                        ;                       j
             Shen, T. T.'  Control Techniques for Gas Emissions  from Hazardous
             Waste Landfills.  J. of Air Pollut. Control  Assoc.  31: 132-135,  1981.

             Swope, G. L. Revegetation of Landfill  Sites.   M. S.  Thesis.  The
             Pennsylvania State University, 1975.   98 pp.
                        l                       i
             Vogel, W. G.  A Guide for Revegetating Coal  Mine Spoils in  the
             Eastern United States.  Gen. Tech.  NE-68.   USDA,  NE Forest Experiment
             Station, 1981, 248,,pp.            j
                      9-1/3"
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             A-,-
                                           :'.  38  .-':

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                                    TECHNICAL REPORT DATA
                             (Please read Instructions on the reverse before completing)
1. REPORT NO.
                                                              I. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
                                                              5. REPORT DATE
    STANDARDIZED  PROCEDURES FOR  PLANTING VEGETATION  ON
    COMPLETED SANITARY LANDFILLS
                                                            6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
                                                              8. PERFORMING ORGANIZATION REPORT NO.
    Edward Gil man.  Franklin Flower.  Ida Leone
9. PERFORMING ORGANIZATION NAME AND ADDRESS
    Rutgers University
    New Brunswick,  New Jersey
                                                            10. PROGRAM ELEMENT NO.

                                                                 BRD1A     	
                                08903
                                                            11. CONTRACT/GRANT NO.
                                                                  CR807673
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal  Environmental Research Laboratory--Cin.,  OH
Office of  Research and Development
U. S. Environmental Protection  Agency
             Db.tQ..., 15363	
                                                            13. TYPE OF REPORT AND PERIOD COVERED

                                                            Final  August iqan-.luly
                                                              14. SPONSORING AGENCY CODE
                                                                 EPA/600/14
15. SU
  Project Officer:   Robert E. Landreth
                                                 513/684-7871
!6. ABSTRACT
  A manual was  developed for those  charged with establishing a vegetative cover  on
  completed landfills.   Special  problems associated  with growing 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.
17.
                                 KEY WORDS AND DOCUMENT ANALYSIS
a.
                   DESCRIPTORS
                                              b.IDENTIFIERS/OPEN ENDED TERMS  C.  COSATI Field/Group
13. DISTRIBUTION STAT6M6N1
                                              19. SECURITY CLASS (This Report!
                                                 Unclassified
                                                                            21. NO. OF PAGcS
          RELEASE  TO PUBLIC
                                              20. SECURITY CLASS (This page/
                                                 Unclassified
                                                                            22. PRICE
 EPA Form 222Q-! (R«v. i-77)   PREVIOUS soi TION is OBSOUSTE

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