-------
     Coastal marshes develop on relatively flat terrain between the limits of
normal high and low tide of protected bays, estuaries, and lagoons.  They are
dominated by a few species of tall emergent reed-like vegetation which are
tolerant of rhythmic submergence and saline conditions.  The water may be nearly
fresh or nearly marine or highly variable in salinity, and flushing occurs with
each tidal cycle.  Within saltwater marshes there is a gradual build-up of organic
peat deposited by the vegetation itself.  Highly dendritic tidal creeks dissect
the marshes and serve as avenues of entrance and egress of the tidal waters
which alternately flood and drain the marshes.  Because of their adaptations to
the intertidal zone, salt marshes are highly sensitive to even minor change
in water levels.
     The coastal marsh ecosystem lies from a few feet above sea level to a
few feet below it.  Hence, it is subject to the ebb and flow sweeping action of
tidal currents, and all must be tolerant of some salinity change.  All trap
suspended nutrients by slowing down the water currents, and they all provide
shelter and food for a variety of small brackish water and marine animals.  These
are among the most productive ecosystems of the world with annual production
rates running around five tons per acre.  Much of this plant production becomes
available as organic detritus which provides the chief food base for the coastal
fish and shellfish populations of commercial importance.  Without these important
production and nursery areas, our coastal seafood resources would suffer severe
decline.
     Although tolerant of short-term inundations with fresher or more saline
waters and even short-term exposure to the air, these systems cannot tolerate
long-term changes in these environmental factors.  Drying of the habitat or
major intrusion of fresh- or saltwater has been shown to change the composi-
tion of the dominant vegetation with long-term erosion of the productivity of
these systems.
     The marsh vegetation is dominated by several species of the tall Spartina
grass and to lesser extents by other emergent species such as Distichlis, Juncus,
and Salicornia.  Around the bases of these plants and on the surfaces of old
leaves grow a variety of filamentous algae including blue-green, brown, and red
algal types.  On the mud flats between the bases of the plants grow a variety of
                                     7-3

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diatoms and blue-green algae.  Plant production of the marsh is dependent upon
all three groups of producers, the tall emergent species, the filamentous attached
forms, and the mud flat inhabitants.
     Only grasshoppers and a few birds such as seaside sparrows may be found among
the tall Spartina grass, but the water and mud flats are teeming with animal
life.  This includes snails, mussels, and oysters, as well as a variety of worms,
crabs, shrimp, and small fishes.  Many of the crabs, shrimp, and fishes are juve-
niles of species which support the commercial catch as adults.  Large numbers
of shore and wading birds forage in these marshes at low tide.
     Studies have shown that there is a regular export of decomposing organic
matter through the tidal creeks to the estuaries, but the major export occurs
when storms inundate the marshes with high water and flush out great quantities
of organic matter to the estuaries and the continental shelves.

7.1.1   Occurrence of Coastal Marshes
     Coastal marshes (or intertidal emergent wetlands) are recognized as an eco-
logical class within the Estuarine System of a wetland classification (Figure
7-1).  There are nearly 70 million acres of natural wetlands in the continental
United States of which coastal marshes total about 17.5 million acres.

7.1.2   Related Land Tyj)es_
     Coastal marshes as an ecosystem type are very similar to coastal swamps
and grass flats.  All are emergent wetland ecosystems (Figure 7-1).
     A coastal swamp is an association of mangrove trees which grows in the sea
or in the water of sheltered bays and estuaries of subtropical regions.  The
average water depth may be from a few inches to about four feet.  Extensive prop
root systems reduce the action of waves and tidal currents and produce a charac-
teristic set of internal environmental conditions.  Water flow is greatly reduced.
Sedimentation is high, and much organic matter accumulates.  Oxygen levels are
low, and the environment is in many respects similar to that of anaerobic sub-
merged soils.  Strong gradients in oxygen content and other factors exist from
the periphery to the interior of the swamp.  In some cases, saltwater swamps
grade inland into saltwater marshes.
                                     7-5

-------
     Coastal swamps are dominated by the low, bush-like red. black, and white
mangrove trees.  A few other shrubs and vines may also be present.  The exten-
sive root systems developed by the mangroves provide surfaces for attachment of
filamentous algae, and the surface muds may support large and productive diatom
floras.  Large numbers of oysters are often found attached  to the mangrove roots;
a variety of small crabs, shrimp, and fishes feed on the organic forage around
the roots and mud flats at low tide; and birds nest in the  branches of the man-
groves.
     Grass flats or submarine meadows consist of a few species of grasses which
are tolerant of continual submergence in salt and brackish waters.  They are
normally found from the low water line to a depth of about three feet, but they
may extend considerably deeper in very clear waters.  Although seldom found in
very strong current, they are most luxuriant where there is moderate flushing.
The long flat blades of the dense beds protect the bottom from erosion, and
extensive deposition creates a substratum of finely particulate, high organic
muds.  Sufficient water penetrates the beds to-maintain high oxygen levels in
the water above the bottom.
     The grass flats are dominated by eelgrass (Zostera spp) in northern lati-
tudes or by turtle grass (Thalassia spp) or manatee grass (Cymodocea spp) in
the more tropical areas.  The long grass blades are often clothed with a layer
of attached filamentous algae which produce organic matter and which also act
as brushes to remove suspended matter from the flowing water above.  Many small
animals live among the stems and roots of the grass beds, and larger fishes and
birds forage there.

7.2   NATURAL PERTURBATIONS
     Coastal marshes are generally considered to represent a serai stage in the
succession of water to dry land.   In areas with relatively stable climatic
conditions, succession is extremely slow and the marsh maintains the same appearance
year after year.   In other areas, violent climatic fluctuations cause coastal
marshes to revert to an open water phase in some years and the concept of succes-
sion in the normal sense of the word has little meaning.  Fire has been shown to
play an important role in maintaining coastal marshes.  Coastal marshes can
recover from fires in a couple of years if the fire does not burn down to the
bare soil and thereby permit excessive erosion.
                                    7-6

-------
     Large storm systems  (e.g., hurricanes) can cause extensive damage to coas-
;tal wetlands due to erosion and excessive freshwater runoff.  Erosion physically
disrupts  the marsh while  the freshwater inflow may temporarily upset biota
adapted to marine or estuarine conditions.  These effects are generally short
term and  marsh recovery would be expected within a few years.  Studies of natu-
ral perturbation show  effects on primary and  'secondary productivity but these
perturbations are well within the range of homeostatis within the marsh ecosystem.
 7.3   MAN-MADE  PERTURBATIONS

 7.3.1   Impact on  Baseline  Ecosystem  Components
     The  coastal  marsh  is  a semi-aquatic  system  in equilibrium with the prevail-
 ing  climatic, hydrographic, geological, and biological forces of the coast.
 Even slight modification in the  level of  the water table or the rate of surface
 freshwater flow greatly modifies the biological  characteristics of the system.
 Although  the coastal marshes vary greatly in detail, a more or less typical
 marsh has freshwater vegetation  at the  landward  side, saltwater vegetation at
 the  marsh is drained by highly dendritic  tidal creeks which empty into the bay
 or estuary.  Freshwater entering along  the upper edges of  the marsh drain across
 the  surface and enter the  tidal  creeks.
     Many of the  marshes of the  Atlantic  and Gulf coasts have undergone great
 attrition in recent years, primarily as a result of  levee  and canal construction.
 A levee placed  across the  upper  end  of  a  coastal marsh has the following primary
 effects:
      — cuts off  all distributaries  feeding the  marsh
      — prevents  freshwater flooding
      — prevents  annual flushing
      — prevents  annual renewal  of  sediments and nutrients
      — ends  foi-mation  of  new  marshes.
      Canals  which lace  the coastal  marshes for navigation, pipelines,  or mosquito
 control have  the  following primary  effects:
      —  intercept and  carry off freshwater drainage
      —  block  freshwater from  flowing  across  the portion  of  the  marsh that
         is  seaward of  the  first canal
      —  rapidly carry  off  freshwater to the bay  or estuary

                                      7-7

-------
     — lower the water table
     — permit saltwater intrusion well into the marsh proper.

 7.3.2   Unassisted  Recovery  Sequence
     The biological consequences are clear.  On the Atlantic coast where sub-
sidence rates are fairly slow, the marsh vegetation gives way to dry land vege-
tation with accompanying changes in the animal populations.  Bourn and Cottam
reported on a detailed 10-year study of the fate of a drained coastal marsh in
Delaware.   Prior to canalization, 90 percent of the marsh vegetation was salt-
marsh cordgrass (Spartina alterniflora) with smaller amounts of other marsh
species, especially at higher elevations.  A few open water areas supported
luxuriant growths of widgeongrass (Ruppia maritima) and other submerged aquatic
species.
     Ten years after ditching had taken place the wetland plants had been reduced
to small groups in the remaining low spots and along canal margins.  Groundsel-
bush (Baccharis halimifolia)  dominated the plant community which now was made up
largely of dry land species such as asters, goldenrods, terrestrial grasses, and
young trees (pine, juniper, sweetgum, maple, and hawthorn).  Aquatic animal
populations of the ditched areas had been greatly reduced in areal extent and in
density, even in the wetland habitat which still remained (Table 7-2).   The
density of the total invertebrate population was reduced from 39 to 97 percent
in the various samples, and the mollusks and crustaceans, which make up important
food items for many fishes and shore birds, were reduced 32 to 100 percent.  Open
aquatic areas, which formerly supported widgeongrass and other important duck foods,
had been reduced to mud flats and dry land.  Thus, the wetland habitat, important
in the production of fishes,  shellfishes, ducks, and wading birds, had given way
to land with its low wildlife values.

     On a subsiding coast, such as occurs  in southern Louisiana, elimination of
the normal freshwater and sediment input upsets the land-water equilibrium, and.
the subsiding marsh tends to become an open water area.  This tendency is intensi-
fied by canals which drain the marshes, enhancing compaction.  These canals tend
to grow wider as a result of marginal  subsidence, wave erosion, and disturbance
from boat traffic.  Plant production by marsh grasses of the Gulf coast is very
high, exceeding 10 tons per acre per year  and a great deal of additional plant
production occurs in the marshes due to attached algae, mud flat diatoms, and

                                      7-8

-------
   Table 7-2.   Effects  of ditching  a  Delaware  tidewater marsh  on  the  aquatic
               invertebrate  populations.   Vegetational zones are  characterized
               by the dominant  plant  species.   Six-foot square quadrants were
               sampled  for comparison of  invertebrate  density  in  the  drained
               and undrained sections of  the marsh,  and they represent  three
               consecutive years  of sampling during  the months of April-December
               (from U.S.  Environmental Protection Agency^)-
   Vegetation  Zones
 Feet above mean
sea level (for the
undisturbed marsh)
                                                      Percent  reduction of the
                                                      invertebrate  populations
    Total
invertebrates
Mollusks and
crustaceans
Saltmarsh cordgrass
(Spartina alterniflora)
Saltgrass
(Distich! is spicata)
Saltmeadow cordgrass
(Spartina patens)
Saltmarsh bulrush
(Scirpus robestus)
1.88-2.93
2.35-2.90
2.58-3.32
2.75
39-82
64-88
41-97
50-97
32-95
82-94
55-100
58-98
phytoplankton in the shallow waters.  A large fraction of this organic matter

is exported through tidal creeks to nearby bays and estuaries.  When the marsh

becomes an open water area, however, production is apparently reduced, and

instead of exporting organic matter, the area becomes a nutrient sink.  Birds

and mammals no longer find food and refuge among the marsh grasses, and canals

create migrational barriers to terrestrial and semi-terrestrial animals which

utilize the marsh.  Complete shifts in vegetation accompany increased salinity

and subsidence.
     Saltwater intrusion increases the salinity of the marshes,  eliminating

the broad mixing zone so important as nursery grounds for juvenile fishes,

shrimp, and crabs.  In deeper channels where reducing conditions prevail,

large quantities of hydrogen sulfide are produced which are toxic to the marsh
       o
grasses  and to the aquatic animals.  Acid conditions of the canals may also

result in release of heavy metals from the sediments.  As a result of habitat

loss, decreased food supply, increased salinity, and increased hydrogen sulfide,


                                      7-9

-------
populations of aquatic animals are adversely affected.  Moore and Trent  compared
oyster production  in natural and canalized marshes.  They found that in the
altered marsh the  set of young oysters was reduced by over 90 percent, juvenile
growth was slowed, average length was reduced by 36 percent, weight was reduced
by  27 percent, and mortality was increased by 39 percent.  As a result of these
and other studies, St. Amant (unpublished) has concluded that lack of freshwater
has drastically modified the ecology of coastal marshes and severely damaged
production of valuable oysters, shrimp, fur animals, and waterfowl.
     In areas of eroding shorelines where dredged spoil has been used to sup-
port vegetation, both seeding and transplanting methods have been used to re-
develop the flora.  Both methods have been highly successful and after two grow-
ing seasons, little or no difference existed in appearance and primary produc-
tivity between these new marshes and long established natural marshes.
     The methods of soil removal are dependent on the depth and characteristics
of the unstable material as well as upon the nature of the underlying stable
substrate (Figure  7-2).  Where depths of unstable material do not exceed about 10
feet a dragline, shovel, or dredge may be used to excavate the unstable material
to sufficient width.  The excavated material handled by dragline or shovel is
usually side cast beyond the excavation, forming a spoil bank, and it must be
removed a sufficient distance to prevent lateral displacement back into the
excavation.
     Where deeper unstable deposits are encountered (about 10 to 25 feet), dis-
placement methods are commonly used.  In such methods the fill is advanced by
end-dumping and placement with a bulldozer in a V-shape (i.e., highest along the
central crest).  Fill height is increased until the load is sufficient to produce
failure in the underlying unstable materials, displacing them laterally.  Dis-
placement may be accelerated by jetting with water prior to, during, and after
displacement of the fill.  As the fill settles,  additional material must be
placed to maintain the grade.  The weight of the fill  will cause lateral compres-
sion in the displaced materials which may result in settling and horizontal
movement of the shoulders for several years.
     Displacement of unstable materials under the fill may also be accomplished
by blasting.   In the "underfill" technique the surface layers are broken with
equipment or light charges, the fill is placed,  and explosives are then positioned
through the fill in jet holes or casings.  Usually one to three rows of explosives

                                     7-10

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are placed along the center line about midway between the fill bottom and the top
of the underlying solid substratum.  In addition, at each edge of the fill two
or three rows of charges are placed 4 to 5 feet below the surface.  The explo-
sion displaces the soft materials, creating a cavity under the fill which then
settles rapidly.  In the "toe-shooting" technique the soft material is displaced
by blasting ahead of the advancing fill.  Added fill material is pushed into the
cavity left by the blast, and the fill is advanced with a V-poir.t which displaces
the soft material and', develops a wave in front of the fill.  In the process, the
front face of the fill is overburdened, and the explosive charges are placed
around the toes of the fill near the bottom of the soft material.
     The cutting and digging action of the dredging operation breaks through
the thin oxidized layer of the submerged soil and exposes the deeper unoxidized
layer.  Furthermore, most of the sediments placed in suspension are removed from
this layer and, hence, are in the chemically reduced state.  Such materials have
very high chemical and biological oxygen demands.  Frankenberg and Westerfield
calculated that some dredge spoils require 535 times their own volume of oxygen
for complete oxidation, and Brown and Clark  reported oxygen levels near dredges
18-83 percent below normal.  Both the sedimentary particles and the interstitial
waters released contain immediately toxic materials such as hydrogen sulfide,
methane, and a variety of organic acids, ketones, aldehydes, etc., as well as
heavy metals and pesticides which exhibit persistent toxic effects.  Turbidity,
per se, reduces light penetration and interferes with photosynthetic production
of oxygen, and it tends to elevate water temperatures.  Eventually the suspended
material settles to the bottom either near the dredging site or far downstream.
Thus, there is a redistribution of sediments together with whatever nutrients
and chemical pollutants which they may contain, and this may result in modified
bottom topography and altered patterns of water circulation.  Such sedimentation
problems are greatly accentuated when dredge spoil is placed back into the water.
General and immediate effects of dredging and spoil placement are listed in
Table 7-3.
     In coastal marshes the matter is complex because of the adjacency of salt-
water and the natural process of coastal subsidence.  Coastal marshes, in the
undisturbed state, represent vast drainage systems.  Freshwater enters on one
side, generally from the floodwaters of annual river overflow, and it gradually
works down to the coast in a broad, flat surface sheet.  Occasional creeks and
bayous aid in the runoff.  Near the estuaries the marshes are dissected by

                                     7-12

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dendritic tidal creeks.  Thus, through the marsh there is naturally a gradual
salinity gradient from freshwater to the more brackish waters of the estuary.
Marshes overlie deep layers of unconsolidated river deposits which gradually
undergo compaction as the water is squeezed out.  Such marshes would gradually
subside, but sediment input through river overflow and buildup of organic matter
through plant growth counteracts this tendency and maintains the delicate land-
sea, and freshwater-saltwater balances.
     Soil removal (including denuding) from marshes accelerates the rate of
freshwater runoff, and it may lower the water table of the soil, drying out the
higher areas of the marsh.  Artificially denuded areas do not correspond to nat-
ural coastal meandering tidal streams.  They may, however, erode to form open
canals.  Once opened, such canals tend to widen due to tidal and other natural
action or due to the effects of boat traffic.  Land loss from canal erosion has
reached serious proportions in Louisiana and elsewhere.
     In addition to draining away the freshwater, the canals offer paths for
saltwater penetration of the marshlands, and this is especially prominent in
the deeper canals.  Since rivers no longer are permitted to flood the upper
reaches of the marshes, they are now deprived of both the annual freshwater
and the annual sediment load.  Thus, as compaction and subsidence proceed, and
as saltwater penetrates through the canals, the effect of saltwater is being
felt further and further inland.  Vehicular traffic over the marshlands (mud-
boats, marsh buggies, and heavy equipment) associated with restoration activities
accentuates this problem.

     Marsh canals have very high contents  of organic matter and high oxygen
demands.  Yet water  circulation is often poor,  and this  leads to reducing or
near reducing conditions, especially  in the bottom water.  Saltwater is rich  in
sulfates, and when the sulfates enter  the  reducing conditions,  they are con-
verted to sulfides,  which are very potent  biotoxins.   Precipitated iron sulfide
is  a common marsh deposit.
     Spoil banks are often cast up alongside the  canals  creating a surface dam
effect.  Such banks  impound waters on  both sides  and  seriously  interfere  with
normal surface  drainage patterns.  The spoil banks directly cover  vast acreages
of  marshland, and erosion from  the  spoil banks  tends  to  drain back  into the
canal, on one side,  and  into  the marshland,  on  the other.   Since the  sediment

                                     7-14

-------
itself is mostly in the chemically reduced state, it tends to lower the oxygen

concentration of the canal waters when it flows back.  Erosion of spoil banks

and shallowing of canals require redredging in a never-ending cycle.  Effects

of soil removal and spoil placement in marshlands are listed in Table 7-4.
          Table 7-4.   Effects of soil  removal  and placement of dredge
                      spoil  in marshlands (modified from U.S.  Environ-
                      mental  Protection Agencyll).
              Interference with surface drainage patterns

                  Acceleration of surface drainage by canals

                  Damming of surface drainage by spoil  banks

                  General acceleration of freshwater runoff


              Loss of marshland habitat

                  Loss due to canalization

                  Loss due to water table lowering
                  Loss due to erosion and widening of canals

                  Loss due to spoil coverage
                  Loss due to acceleration of marsh subsidence


              Acceleration of saltwater penetration


              Conversion of sulfates (of saltwater) to sulfides in the
                  canals and precipitation of iron sulfide in the
                  canals

              Erosion of spoil banks and distribution of chemically
                  reduced sediment into canals and open marsh
7.4  EFFECTS OF CLEAN-UP PROCEDURES
     ON COASTAL MARSHES

    Clean-up procedures considered for marsh land types include temporary con-

tainment, contaminant removal and barrier exclusion.  The following subsections

discuss the effects of these treatments on the marsh ecosystem.

    The first techniques considered are those which may be applicable for pre-

venting further spread of contaminants across the marsh until contaminant removal
                                     7-15

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by clean-up can be accomplished.  The various alternative methods are considered
to be appropriate for coastal marshes if they might pre/ent further redistri-
bution.  The techniques discussed in this subsection include chemical stabili-
zation, clear cutting, stumping and grubbing, plowing, and application of un-
contaminated soil cover.
    (1-1)  Chemical Stabilization
    Chemical stabilizers are materials employed to bind soil particles together
as an aid to preventing erosion.  Chemicals may also be applied to mulch mater-
ials to act as a binding agent.
    The effect of chemical stabilizers is usually temporary and in the water-
logged soils of the marsh environment may be very transitory.  Because of this
characteristic, chemical stabilization may not be an appropriate treatment for
large areas.  However, for small plots, this approach may be of some use.  Since
chemical application is commonly a part of revegetation programs, little eco-
logical impact would be expected from application in marsh areas.
    Certain chemical stabilizers are designed to reduce the rate of infiltration
In a coastal marsh environment, with the frequent flooding associated with high
tides, infiltration reduction has little meaning.  Use of this treatment is
therefore inappropriate for this land type.
    (1-2)  Clear Cutting Vegetation
    Clear cutting would be an appropriate treatment for relatively upland por-
tions of coastal marshes which support significant populations of trees and
to large emergent stands such as found in mangrove swamps.  Since root systems
would not be removed, erosion potential will clearly be appreciably diminished
relative to root layer removal techniques discussed in subsequent sections.
Root and/or stump sprouting is likely to occur and recovery would thus be ac-
celerated relative to total clearing treatments.

     (1-3)   Stumping and Grubbing
     Stumping and grubbing involves the removal of all surface vegetation and
major root systems.  Disposal of vegetation may be by natural decomposition or
by burning, depending on the volume of organic material and the properties of
the contaminant.
                                     7-16

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      The  clearing  of  the  land removes the vegetative cover and permits the rain-
 fall  to strike  the bare land surface.  These processes  lead to increased surface
 runoff and  severe  erosion.  The  effects will be accentuated in rainy weather.
 In  dry weather  considerable quantities of soil in relatively upland areas may be
 raised as dust  clods  which will  be transported at a later date when the rains
 fall.  Runoff and  erosion will add a great deal of soil solids to the marsh re-
 sulting in  greater water  turbidity and increased sedimentation in tidal creeks.

    Denuded areas  have been shown to lose large quantities of dissolved min-
 erals, particularly sodium, potassium, calcium, magnesium, nitrates, and phos-
phates.   In some cases increased groundwater and springflow has been noted
 immediately following removal of phreatophytes (which normally pump water up
through the roots  to be lost via transpiration), but the springflow may even-
tually diminish as the water table is lowered through lack of recharge.
    If the brush cleared from the land is burned in the flood plain the ashes,
which are highly alkaline, may enter tidal creeks and cause an immediate in-
crease in the pH of the water (in one study the pH jumped almost immediately
from 7.8 to 11.3 and remained high for some time).   In addition,  heat  from
the fire can elevate the marsh water temperature quickly and keep it high for
some hours.
    Denuding equipment in operation as well  as spills in maintenance yards can
result in the passage of petroleum products into the water courses.
    The net result may be summarized in the  following points:
        — loss of habitat  from devegetation  of the  area
        — loss of land fertility from surface erosion and subsurface flow
        — increased erosion from denuding  site activities
        — lowered groundwater level  from  devegetation
        — greatly increased fluctuation  in water level  due to  faster runoff
          following rains  and decreased  flow during  dry periods  because  of
          loss of groundwater
       — greatly increased marsh sediment load due  to  erosion and
          runoff
       — greatly increased marsh turbidity  due to  erosion and runoff
                                     7-17

-------
        — modified chemical composition of the water due to increased
          sedimentation and runoff,  turbidity, leaching of soil
          nutrients.
    As a result of these influences, the coastal marsh will undergo a number
of changes.  The violent fluctuation in water level will result  in greater
freshwater flow rate during wet weather.  The creek beds may be  cut deeper,
the banks will be undercut, and the open water sections will be  widened.   Rif-
fles may disappear and pool areas fill.  Marsh areas may be swept clear by
flood waters.
    Increased sediment loads clog the interstices of riffles, fill the pools,
and cover the bottom generally with a layer of inorganic silt.  Bottom habitat
diversity would be significantly diminished.  Accompanying the increased run-
off, there would be an increase in water turbidity.  This lowers the light
penetration of the water, increases oxygen demand, and modifies  the chemical
characteristics of the water in other ways.  Loss of vegetative  cover and in-
crease in turbidity both serve to elevate the temperature of the water (as
much as 10°F).5
    During dry weather freshwater flow may slack off or it may cease entirely,
since the marsh now receives less groundwater inflow than before.  As pointed
out by Bayly and Williams,  land clearing may so alter the local hydrological
regime that formerly perennial streams may approach or become intermittent.
Since open water pools tend to be reduced or lost, the aquatic habitat may be-
come severely restricted or dried up between floods.  Any water that remains is
now subjected to more rapid and estreme temperature fluctuation in response to
prevailing atmospheric conditions.
    The long-term results will depend greatly upon local circumstances but,
in general, they would include the following:
        — permanent loss of natural land habitat — If the topsoil is
          eroded away, a native ecosystem will not return for many years
        — increased surface runoff and  reduced groundwater  flow — The
          denuded surfaces will continue to yield rapid and  complete runoff
        — persistent chemical changes — The high level of sedimentation
          and turbidity may eventually  taper off.
                                      7-18

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     Recovery after stumping and grubbing would be  dependent  upon several  fac-
 tors including
         — size  of area  denuded (the  magnitude  of the  effects outlined
           above would be  increased with  increasing area)
         — location of disturbed area relative  to open water  (areas
           adjacent to open  water would be subject  to  runoff  effects
           as well as the  erosional influence of tidal currents  and
           wave  action)
         — weather following cleanup  (heavy rains would magnify  runoff
           impacts and extended dry periods would delay recovery by
           possibly drying exposed muds).

     (1-4)    Scrap-ing and  Grading
     Surface  alteration  such as scraping  and grading of a marsh  area would
 have environmental  consequences  similar  to those discussed above for vegeta-
 tion removal.   However, more complete removal  of the  surface layer organic
 matter would result with  this  type of treatment.   In  addition,  epibenthic
 and  burrowing animals would be more  directly affected by surface alteration.
     Because  of  the  relatively  flat characteristics of marsh  lands, grading
 for  containment would not entail  leveling  as may be the case  in  more upland
 ecosystems.  Grading in coastal marshlands  would probably include banking
 of materials so that drainage  patterns would be  from the edges of the af-
 fected area  inward  (the reverse of the normal  drainage pattern).  This could
 alter the  fresh -  salt water gradients within  the marsh and  ultimately modify
 the  biological  character of the marsh.  However, the slight  gradients in-
volved here would undoubtedly  be overcome by tidal and wave  action and flood
 events and eventually more-or-less normal gradients would prevail and con-
 tainment would be temporary.

    (1-5)   Shallow Plowing
    Plowing is not felt to be  an appropriate treatment for a coastal marsh.
 Bottom sediments  in marshes  are continually in a state of flux in response
to tides, waves and runoff events.  Plowing would be not only destructive to
the marsh habitat but would  also probably enhance contaminant mobility by dis-
rupting the hydrologic regime and creating new flow routes.
                                     7-19

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     (1-6)   Deep Plowing
     See treatment 1-5;  this technique is not appropriate for this land type.

     (1-7)   Soil Cover Less than 25 cm
     Because of the scouring action of tides, waves and flood events,  thin soil
 cover may be only a very temporary containment treatment for this land type.
 Thus its use in marsh systems may be limited.
     The effects o£"this treatment are in two areas—the area covered and the
 source of the cover material.  Naturally the magnitude of effects,  and hence
 the restrictions to recovery are a direct function of the area treated.
     In the covered area, the habitat of epibenthic, burrowing and semi-
 terrestrial animals would be destroyed.  Also young stands of marsh grasses
 would be buried and would not be expected to survive.  Larger grasses, bushes
 and trees would not be buried; however machinery used to dump the cover soil
 may be very destructive.
     Recovery would be more rapid than if the covering process was preceded
 by vegetation removal,  as root or stem sprouting may not be prevented with the
 shallow cover.  Vegetation recovery would be fairly rapid with this treatment
 due to the shallowness of the cover which would not bury larger plants and
 which would probably soon erode.

     (1-8)   Soil Cover 25 to 100 am
     If the uncontaminated soil fill is up to 100 cm in depth, then the marsh
has simply been filled in and it no longer can be referred to as a coastal marsh.
The addition of 100 cm of soil may cause the land level to excbed the tidal
ranges and, consequently, the saltwater intrusion which is characteristic of a
coastal marsh will cease to occur.  The marsh may:  (1) cease to have a hydric
soil and begin to behave as a predominantly non-hydric type;  (2) change from a
vegetation cover of hydrophytes to predominantly mesophytes or xerophytes;
(3) change from land that is flooded at some time of the year to land that is
infrequently or never flooded during years of normal precipitation.

    Treatments  considered next  are  those  which  remove  contaminated  soil
layers.   Mechanical  and  chemical  stabilization  after  soil  removal is  also
discussed.
                                      7-20

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    (2-1)   Remove Plow Layer1                             ,.
    The plow layer is defined here as the soil layer from the surface to a
depth of about 10 centimeters.  Removal would be accomplished by hand shovel-
ling or larger digging machinery.  The unstable marsh soils would necessitate
working from platforms, barges or other support structures.
    The ecological effects of soil removal in the marsh would be similar to
those discussed for surface alteration (scraping and grading) and vegetation
removal.  Some inference can also be drawn from the earlier discussion of
dredging effects  (Section III).  Major influences include
        — acceleration of surface runoff
        — alteration of drainage patterns
        — loss of habitat for wildlife
        — increased erosion
        — loss of organic matter and nutrients in surface
          soil layers.
Recovery would be similar to that for scraping and grading but would be
slower because more of the soil-organic layer is removed and elevations are
somewhat altered thus changing the tidal flooding depth.

    (2-2)   Remove Shallow Root Zone
    In a coastal marsh, the root zone is relatively shallow and theiefore,
the effect of soil removal to the depth of a plow layer and/or to the shallow
root zone can be treated the same.  See treatment 2-1.

    (2-3)   Remove by Scraping and Grading,
            Meohanioally Stabilize
    The effects of scraping and grading are discussed in treatment 1-4.
This treatment, combined with "mechanical stabilization" includes removal of
contaminated soils (less than 5 ^m in this case) and compaction of subsurface
soils or surfacing with impervious materials to seal the subsurface against in-
filtration.  As previously noted  (treatment 1-1) infiltration control in a marsh
area which is at' least periodically flooded has little meaning.  Hence this
combined treatment method is inappropriate since mechanical stabilization is
inappropriate.
                                      7-21

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    (2-4)   Remove Plow Layer., Meohaniaally Stabilize
    This combined treatment is inappropriate for the marshland type; see treat-
ment 2-3 and 2-1 for further discussion.

    (2-5)   Remove Shallow Root Zone, Mechanically Stabilize
    This combined treatment is inappropriate for the marshland type; see treat-
ments 2-3 and 2-2 for further discussion.

    (2-6)   Remove by Scraping and Grading,
            Chemically Stabilize
    The effects of this combined treatment are essentially those discussed in
treatments 2-3 and 1-1.  The chemical stabilization method employed would
have to be instituted for erosion control rather than infiltration control for
the reasons previously given.  The erosion control provided would be expected
to be transient but might be sufficient to somewhat mitigate runoff impacts
resulting in a more rapid recovery than scraping and grading alone.

    (2-7)   Remove Plow Layer, Chemically Stabilize
    This combined treatment would result in effects similar to those discussed
for plow layer removal alone (treatment 2-1).  However, as discussed above,
erosional problems would be mitigated temporarily and recovery would be some-
what more rapid than that without stabilization.

    (2-8)   Remove Shallow Root Zone, Chemiaally Stabilize
    The effects of this treatment are discussed in treatments 2-2 and 2-7.
    Barriers to exclude people and to exclude both large and small animals are
discussed in the following treatments.

    (3-1)   Barriers to Exclude People
    It is assumed that exclusion would be accompanied through the use of
barbed wire fencing or some sort of mesh material such as chain link or Cy-
clone fencing, hardware cloth, or poultry wire.
    If a natural state is deemed beneficial, then nothing but benefit can
derive from the exclusion of humans.  Benefits due to increased "naturalism"
will accrue in direct proportion to  the  intensity of previous human use or
intrusion.  Numbers of species and their diversity will certainly  increase as
shy species return to  the marsh; this may be especially true  in  the case  of

                                   7-22

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migratory game fowl if hunting is terminated.  Vegetative cover, arid hence
primary and secondary productivity, will increase if these parameters had been
below maximum levels due to human trampling.  However, note that secondary
productivity is not likely to increase greatly due to the lack of macrophyte-
consuming herbivores which frequent salt marshes.  Finally, erodibility would
likely remain unchanged or perhaps even decrease; indeed, a negative erodibility
may exist for marshes since they are areas of deposition.

     Humans often find cause for interfering in coastal marshes, especially
 when they live near such areas.   Natural marshes are .doomed to self-destruc-
 tion due to sedimentation and consequent evolution (succession) into an.up-
 land habitat.   Part of this evolution is often the buildup of a bar at the  "
 tidal inlet(s),  hence,  the tidal flushing of the marsh is greatly reduced or
 eliminated.  As  this happens, conditions may become anaerobic as water temper^
 ature and salinity rises and, therefore, marsh flora and fauna die and decay.
 Such conditions  create a great nuisance near points of human activity, and
 they provide a haven for insects such as gnats and mosquitoes, further ag'gra-
 vating the condition of local human populations.  For exactly these reasons,
 and also to maintain a maximum level of productivity, marsh channels are often
 dredged regularly, especially at the tidal inlet(s).4  Such dredging also en-
 hances the flood control value of marshlands by providing open channels for
 runoff during precipitation events.  Thus, exclusion of human activity may not
 be taken to include channel dredging, especially if there is significant human
 activity in the vicinity of the contaminated area.  It should be noted that, if
 periodic dredging is performed,  the dredged materials must be checked for con-
 taminant level and, if found to contain unacceptable levels of contamination,
 must be dealt with accordingly.

     (3-2)   Barriers  to Exelude  Large Animals
     Not applicable to this land type.

     (3-3)   Barriers to Exclude Large and Small Animals
     It is assumed that exclusion would be accomplished through the use of
fine-meshed materials, such as screen with mesh diameter less than 1.0 cm, or  "
through the use of solid materials,  for example,  brick and cinder block.
                                     7-23

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     Animals such as mice, voles, raccoons, rabbits, possums, skunks,  weasels,
                                                 4
 and coyotes could be excluded by this treatment.   Mammals rarely live within
 a coastal marsh; generally they reside in nearby upland habitat and use the
 marsh only for forage, consuming seeds, some plants, insects, and other small
 aniirals.  Further, such mammals are noted to be "represented by relatively
 small populations."  Hence, exclusion of these creatures would have very little
 effect on the marsh ecosystem; a slight drop in species diversity and in the
 total number of species occurring in the marsh would be the only noteworthy
 effects.
     However, if a large area, e.g. 1 to 10 km2, were fenced off, the result-
 ing pressure on surrounding lands for forage and prey could cause significant
 harm to these lands.  This also could cause effects on nearby human popula-
 tions ranging from a minor nuisance to a significant economic hardship, for
 example, if the search for food led the displaced animals into human dwellings
 or into agricultural lands, of if predators were forced to prey upon domestic
 animals.

     Birds are the most important small animals in a coastal marshland from the
perspective of contaminant mobility.  Birds forage on seeds, benthic invertebrates,
open channel vertebrates, and insects; some of these prey species may concentrate
a contaminant through direct ingestion (e.g., worms and filter feeders), or
through their own food source which has already ingested a contaminant and per-
haps concentrated it to some degree.  Hence the birds may ingest significant
quantities of a contaminant and may then pass it through their digestive system
and deposit it offsite in feces or concentrate the contaminant in their own tis-
sues and then die or be preyed upon offsite.  The former seems more probable.
The same set of circumstances may also apply to fish and insects, in which cases
the latter event is more likely.

   Therefore it may be pointless to prohibit only horizontal crossings at the
 land surface; some sort of barrier to movements above and below the surface
 may also be desirable.  The effects of such barriers would be considerable,
 compounding greatly as the size of the area of exclusion increases.
                                      7-24

-------
    First, although net secondary productivity may change very little over a
long period of time, large short-term fluctuations may be expected as predator
species and prey species adjust to sudden partitioning from each other.  It
is especially the prey species which may explode in population with a sudden
halt to predation.  "Boom and bust" cycles of prey populations could be ex-
pected as the affected species increase their numbers, outstrip the available
food supply, and die back in catastrophic instances, whereupon the cycle is
renewed.  Ifcan be seen that, within this cycle, vast effects on the food
sources of the former prey species can be expected.
    Additional effects can be anticipated from the elimination of certain
species which spawn in the marshland.  These effects may range from the triv-
ial to the extreme depending on the size of the area fenced from the intru-
sion, the availability of alternative breeding sites, and the importance of
the species whose spawning grounds have been contaminated.
    Additional pressure on surrounding lands from avian predators and for-
agers displaced from the contaminated areas can be highly significant if sur-
rounding marshland is burdened beyond its capacity to produce food for the
                                                                   o
displaced birds.  This could, occur, for example, if half of a 20 km  marsh
were fenced and screened*  Thus, wildly fluctuating populations of predator,
prey, and forage species may occur offsite in areas unaffected by contamina-
tion.
    Finally, diversion of migratory waterfowl from contaminated marshlands
can not only have serious effects on surrounding areas, but may also irrevoc-
ably reduce the populations of sensitive species already pressured by general
habitat reduction, diversion from nesting or wintering sites by human activi-
ties other than habitat reduction, and hunting.  Such effects would be en-
tirely site-specific and cannot be addressed further for the general case.

    (4-1)   Asphalt Hard Surface Stabilization
    This treatment is outside the scope of work.

     (4-2)   Conarete Hard Surface Stabilization
    This treatment is outside the scope of work.

     (5-0)   Application of Sewage Sludge
    This treatment is outside the scope of work.

                                    7-25

-------
     (6-1)  High Presure Washing  (<3 om)
    This treatment is outside the scope of work.
     (6-2)   Flooding to SO am
    This treatment is outside the scope of work.
     (7-0)   Soil .Amendments Added
    ftiis treatment is outside the scope of work.

7.5   RECOVERY AFTER CLEANUP
    Recovery of coastal marsh ecosystems following clean-up operations is de-
pendent upon several factors beyond the characteristics of the clean-up oper-
ation itself.  Included in these factors are
        — the size of the area affected by the clean-up operation
        — location of the disturbed area relative to open water (areas
          adjacent to open water are subject to wave and tidal effects
          as well as fresh water runoff)
        — weather conditions following cleanup  (heavy rains would
          increase runoff erosion problems)
The sequence of events leading to "complete" recovery in a coastal marsh sys-
tem is not a multistep successional scheme such as is the case with develop-
ment of the classic climax forest.  Recovery in the marsh system would be
                                        •
essentially directly from disturbed state  (e.g. denuded) to the original
vegetation type (e.g., Spartina).  Graphs portraying a very general recovery
sequence are provided in Figures 7-3 through 7-5 (see Appendix B).
    The rate of recovery is largely determined by the erosional processes.
which characterize the marsh system and which may be intensified by cleanup.
The growth rate of vegetation is probably secondary to the physical processes
determining soil stability and substrate composition.  With the normal high
productivity rates characteristic of the marsh land type, once erosion is con-
trolled and revegetation initiated, recovery would be expected to proceed quite
rapidly.

7.6   QUANTITATIVE ASSESSMENT OF CLEAN-UP  IMPACTS
    Clean-up procedures in coastal marshes are scaled in Table 7-5 with re-
gard to impact on this ecosystem.  The scaling provides a relative view of
the length of time (in growing seasons) required for complete recovery to the
                                     7-26

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          SOIL STABILIZATION (Chemical)
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Figure 7-3.   Recovery of coastal  inter-tidal  marsh following  chemical

              soil stabilization and application of shallow  soil  cover,
                                  7-27

-------
           VEGETATION REMOVAL
                                                   SOiL REMOVAL
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                               7-28

-------
                    ACCESS BARRIERS
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                        7-29

-------
 "natural" state after clean-up operations are terminated.   It should be
 stressed that these rankings are highly subjective in nature.  The specula-
 tive nature of these results is also emphasized by the location and meteor-
 ological factors which will influence recovery.
     The confidence with which this scaling is provided is somewhat inversely
 related to the size of the area affected.  This results from the uncertainties
 related to recovery processes and the potential for external influences on
 the marsh ecosystem subsequent to clean-up operations.  Hence the scaling
 here is much more relative than absolute  (more numerical than quantitative).
     The rationale for developing Table 7-5 is provided in Section 7.4.   General
conclusions drawn from Section 7.4 and Table 7.5 are presented in the following
section.
     Examination of Table 7-5 indicates that for the 0.01 km  area, the treat-
 ments may be grouped into three basic categories with regard to level of ef-
 fect and length of time to recovery.
     The lowest impact group includes construction of barriers  (3-1, 3-2),
 chemical stabilization alone (1-1), clear cutting  (1-2) and soil covering
 (1-7, 1-8).  Tne common characteristic of this group of treatments is gen-
 erally a lack of disturbance of the root and "native soil" structure. Or-
 ganic muds and root systems may mitigate erosion, which is an  important fac-
 tor in recovery of the coastal marsh.  Naturally, some disruption will occur
 from the means and equipment involved in the clean-up operations.  Hence, bar-
 rier construction  (3-1, 3-2) will have the least impact and soil covering
 (1-7, 1-8) the most within this relatively low impact group of treatments.
     Deep soil coverings  (1-8) may elevate the marsh to a level where the
 natural flooding cycles ar'e eliminated.  Recovery  in such areas would not
 lead to a marsh habitat, but creation of a new terrestrial habitat type with-
 in the coastal marsh.
     The group of treatments which have an intermediate level of effect in-
 cludes surface alteration  (scraping and  grading) alone  (1-4) or accompanied by
 chemical stabilization  (2-6);  stump and  root removal  (1-3);  and removal of
 the plow layer followed by  chemical stabilization  (2-7).  These clean-up
 treatments are characterized by a more severe  disruption of  the native soil
                                     7-30

-------
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structure than would be experienced with the lowest impact group.   Thus the
potential for erosion is more substantial and recovery would be delayed as
a result.
    In addition to increasing erosion, removal of roots and disruption or re-
moval of surface soils would remove the plant and soil materials which would
most enhance rapid habitat recovery.  Root sprouting, which would occur after
clearcutting (1-2) would be eliminated and revegetation would occur via root
systems in adjacent areas and seeds dispersed by wind and flooding of the area.
Revegetation by seeds would be hindered to some extent by surface disruption
and soil removal.
    The most deleterious set of clean-up treatments  include removal of the
plow layer  (2-1) and removal of the shallow root zone  (2-2).  The processes
of increased erosion and delayed revegetation, which are discussed above, are
enlarged by these treatments.
    As previously stated, the level of effect associated with any of the
treatments for the marsh land type  is area dependent.  That is, the effects
generally increase with size of the area affected.   This dependence can be
clearly  seen from the  importance of erosion  in determining recovery and the
importance of neighboring areas for revegetation.  With the smaller sized
clean-up areas, the surrounding area  would  act as  a  buffer for  both tidal
and  freshwater flooding events.  In addition, seeding  and root  sprouting  from
adjacent areas would be more  effective with smaller  cleared zones.  Larger
clean-up sites would benefit  less  from these erosion buffer and revegetation
processes,  and hence  slower natural recovery would be expected.
     Treatments which do not involve disturbing  the spill  area (i.e. natural
rehabilitation  (0-1)  and  barrier  construction (3-1,  3-2)  would not have area
dependent  impacts.   However,  some  increased stress in adjoining areas may re-
 sult with increasing  size of barrier  enclosures.
     As discussed in the preceding sections several of the alternative clean-
 up treatments may effectively destroy the marsh land type.   In these instances,
 recovery would not be to the original habitat form.  Such treatments include
 2-2, removal of the shallow root zone (less than 40 cm), and 1-8, deep soil
 covering (up to 100 cm).  The flooding cycle may be disrupted  to the extent that
 the former treatment results in an open water area  and the latter in a more
                                      7-32

-------
 dryland environment.   Because of these consequences,  these treatment types  may
 not be reasonable with regard to recovery  considerations.   The  effects of
 other treatments  are  probably not irreversible  although  subsequent  erosional
 damage may result in  an extended recovery  period,  particularly  for  larger
 treatment  areas.

 7.7   CONCLUSIONS
      Of the clean-up  treatments  considered, several were concluded  to be inap-
 propriate  for  the coastal marshland type.  Shallow and deep plowing is not  ap-
 propriate  for  containment of  spill materials.   Mobility  would be enhanced rather
 than retarded  by  this action.  Also, mechanical stabilization is inappropriate
 as  a mechanism for sealing the marsh soils against infiltration.  This is because
 infiltration control  has no clear meaning  for a frequently flooded  environment
 such as a  marsh.   For similar reasons,  some chemical  stabilizers are inappropri-
 ate treatments in coastal marshes.  However, for binding, soil materials together
 to  mitigate erosion,  chemical  treatments may be useful as  a temporary measure,
 particularly for  rather small  disturbed areas.

     Soil removal methods were  concluded to be the most deleterious  to marsh
 recovery.   Effects  of such treatment increases  with the  depth of removal.
 Deep  soil  coverings may have  similar effects.   In  fact,  appreciable eleva-
 tion alterations in either direction may effectively destroy the marsh hab-
 itat; recovery may be to more  terrestrial or to open-water  communities.  Chem-
 ical stabilization may mitigate erosion and thus aid recovery for all soil  re-
moval techniques from scraping and grading to removal of the shallow root
 zone.  Vegetation removal was  felt to be less destructive than soil removal
 treatments since the substrate materials which  supported "climax" vegetation
may remain largely undisturbed.  Clear cutting  is certainly less detrimental
than removal of all vegetation and roots.
    Barriers were felt to have little overall effect on the coastal marsh
although certain stresses in neighboring areas may result.
                                   7-33

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 7.8   COASTAL INTER-TIDAL MARSH REFERENCES


 1.   Bayly,  I.  A.  E.  and  W.  D.  Williams.   Inland  Waters  and Their  Ecology.
     Longman,  Australia,  1973,  316 pp.

 2.   Bourn,  W.  S.  and C.  Cottam.   Some  Biological Effects  of  Ditching Tide-
     water Marshes,  Res.  Rep.  19,  U.S.  Fish  and Wildlife Service,  1950,  30 pp.

 3.   Brown,  C.  L.  and R.  Clark.   Observations of  Dredging  and Dissolved  Oxygen
     in a Tidal Waterway, Water Resour.  Res.  4(6):1381-1384,  1968.

 4.   California Department of  Fish and  Game.   The Natural  Resources  of Capinteria
     Marsh and Recommendations for Use  and Development,  Coastal  Wetlands Series
     No. 13, 1976.

 5.   Chapman,  D. W.  Effects of Logging  Upon  Fish  Resources of the  West Coast,
     J. Forest., 60:533-537, 1962.

 6.   Frankenberg,  D.  and  C.  W.  Westerfield.   Oxygen Demand and Oxygen Depletion
     Capacity of Sediments from Wassaw  Sound, Georgia,  Bull.  Georgia Acad.- Sci.,
     1969.

 7.   Moore,  D.  and L. Trent.  Setting,  Growth and Mortality of Crassostrea
     virginica in a Natural Marsh and a Marsh Altered by Housing Development,
     Proc. Nat'l.  Shellfish Assoc. 61:51-58, 1941.

 8.   Smith,  W.  G.  Spartina "Die-back" in Louisiana Marshlands, Coastal Studies
     Bull. Special Sea Grant Issue, 5:89-96, 1970.

 9.   U.S. Dept. of Interior.  Interim Classification of Wetlands and Aquatic
     Habitats of the United States, U.S. Fish and Wildlife Service,  1976, 109 pp.

10.   U.S. Dept. of Interior.  A Study of the Disposal of Effluent  from a Large
     Desalinization Plant, Office of Saline  Water R§D Prog. Rep. No. 316, 1968.

11.   U.S. Environmental Protection Agency.  Impacts of Construction Activities
     in Wetlands of the United States,  Rep.  No.  EPA-600/3-76-045,  1976,  392  pp.

12.   Whittaker, R. H.  Communities and Ecosystems.  The Macmillan Company,
     London, 1970.
                                     7-34

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              PART  II
        MANAGED ECOSYSTEMS

CHAPTER 8,  AGRICULTURAL LAND AREAS
CHAPTER 9,  URBAN/SUBURBAN LAND AREAS

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                                  CHAPTER 8
                                 AGRICULTURE
8.1  OVERVIEW
     Lands used for the production of renewable resources and products con-
sumed as food, fiber, timber, and feeds for livestock are by definition agri-
cultural lands.  Crops raised for livestock feeds are discussed as forage,
permanent pasture, rangeland and the native pastures of woodlots.  Plant spe-
cies discussed range from local area natives to patented specialty cultivar
crops.
     In the broad sense, agricultural land could include tundra crops of li-
chens consumed by reindeer herds and the alpine meadows grazed by rodent her-
bivores.  A narrower view is held in this chapter.  Agricultural lands are
considered to be those managed to produce crops at commercially significant
rates for food, feeds, and fibers.
     In this chapter the impacts by cleanup are taken as short-term disturb-
ances because the vegetative component can be replaced precisely—for a price.
Mature deciduous trees as large as 20 to 23 cm in diameter and 8 meters tall
can be dug up, moved, and replanted in normal landscaping.   Sodding or reseed-
ing is likewise economically determined as are most decisions about rehabili-
tation of agricultural lands after cleanup of some contaminant.  As a routine
practice in the deciduous forest, a farm can be cleared of standing crops,
whether small grains or timbered woodlot, surface-mined for coal, the spoils
graded to the original contour, limed, fertilized, reseeded, and be back in
full production in 2 years.  Equipment used in surface mining is different
from earthmoving equipment for local road building, light building construc-
tion and farming.  In general, surface-mining earthmoving equipment is orders
of magnitude larger than usual construction equipment.
     Agricultural land is estimated to be from 526 million hectares to 930
million hectares in the United States  but a variety of figures are used for
agriculture depending on the author's interest.  The percentages of use are

                                     8-1

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approximately 25 percent for grazing in livestock production and 20 percent
for crop production.
     This chapter concentrates on farming in three of the natural ecosystems.
These are the hot desert of the southwestern United States,  where irrigation
supplies almost all agricultural water supply, the adjoining midcontinental
grasslands, and the formerly hardwood forest areas.  These are located as
defined in Figure 8-1.  Because it lies in the intermediate position between
the other two sources of agricultural land, and because almost the entire
grassland has been appropriated for agriculture, the prairie is described in
some detail with its crops.  The irrigated desert is confined to gently slop-
ing or flat terrain and the actual commercial use is a small portion of the
desert terrain.  Deciduous hardwoods occupy rolling to steeply sloping terrain
but agriculture is practiced on the flatter slopes which, as in desert, are
only a fraction of the total area.
     Agriculturally important, the midcontinental grasslands in Figure 8-1
reach from the 30th parallel in the south to the north beyond the Canadian
border.  Bordered on the west by the Rocky Mountains, they rise along the
105th meridian from the central Mexican border into Wyoming, turning north-
westly across 8 degrees of longitude before meeting the Canadian border.  The
eastern grasslands boundary lies along the 96th meridian with a major incur-
sion, generally northeast on a concave arc, from the Red River into south cen-
tral Ohio.  The east grassland boundary keeps west of the Mississippi River
to the Missouri River, crosses both in a few miles and arches north of the
Ohio River into central Ohio, north across Ohio, and turns generally west to
recross the Mississippi and parallel it to the northwest, crossing into Canada
on the 96th meridian.
     Topography of the agricultural prairie ranges from the western short
grass high terraces and alluvial fans across the plains to the steep hills and
lakes on the eastern fringes of Illinois and west Ohio.  The wide, level to
gently rolling plains with tree-clad streambanks in the prairie midsection
were the first to fall totally to the plow as croplands.  Hard red winter
wheats grow in -the southern prairie and grade into hard spring wheats in upper
Nebraska north to the Canadian border.    Annual precipitation in the winter
wheat belt ranges from 350 mm in eastern Colorado, Wyoming, and Montana to

                                      8-2

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900 mm in eastern Kansas and Oklahoma, with warmer summers and longer growing
seasons than the spring wheat belt.  Precipitation" in the spring wheat belt
ranges from 300 mm in northern Montana to 600 mm in western Minnesota and
eastern Dakotas.  Generally, the separation of the winter and spring red
wheats is the isotherm of 18°C for the three summer months of growth into
ripeness.
     Precipitation regimes for prairie are shown in Chapter 2, Part I, and
these are basic figures around which agricultural needs are managed.  In the
west side near the Little Powder River in northeast Wyoming, annual rainfall
is 400 mm with an evaporation potential for 1500 mm in an area where wheat
and oat agriculture displaced mixed prairie grassland and artemesia species,
but the primary use became cattle-grazing because of the combination of lim-
ited rainfall and deficiencies in soil phosphorus and nitrogen.
     The physical characteristics of prairie soils reflect the environmental
regimes of the grasslands as shown in Table 8-1.  On the Missouri side, the
soils are deep and the rainfall is sufficient for tall grass.  The Colorado
side of the prairies have permanently dry subsoil and short grass.  Between
these boundaries lies the minimum line of annual runoff shown in Figure 8-1
as the 2-cm precipitation isogram.  The small grains straddle this precipita-
tion feature and their presence results in the designation of "breadbasket."

Table 8-1.  Relationship between annual precipitation, species composition,
            and moisture consumption, Rocky Mountains to Missouri transect
            of prairie (adapted from Jenny

Indigenous
Plant
Community
Grama grass
Buffalo grass
Wire grass
Bluestem grass
Bunqh grass
Bluestem grass
Sod grass
Depth to
permanently
dry zone
(cm)
30-36
60-80
85-115
absent
Approximate
annual
pptn
(cm)
<45
45-55
55-70
70-100
Plant
height
(cm)
10-35
45
75
110
Region of
observations
Eastern Colorado
Western Kansas
Central Kansas
Eastern Kansas and
Western Missouri
                                     8-4

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8.2  NATURAL PERTURBATIONS               .          .
     The significant agricultural event in physical and economic terms is the
                                  18
loss of soil by erosion processes.    These losses are generated by two dif-
ferent agencies, wind and water runoff.  West of the 2-cm isogram (Figure 8-1)
erosion is driven by wind.  East of the 2-cm isogram water runoff is the
principal erosive force.
     Publications dealing with erosion are numbered in the thousands.  One
agency field office has collected 2,500 reports, bulletins, and books on wind
erosion alone.   This author estimates runoff erosion publications number
more than twice as many as cited for wind erosion.  A simplification is called
for.
     The national wind erosion area is defined in Figure 8-2, while water
erosion sites are shown in Figure 8-3.
     Wind erosion data and its erosive forces are used in general predictions
of soil loss as shown in handbooks.   However, these must be used with cau-
tion.  Attempts to estimate wind erosion by land types across the spectrum of
suggested cleanup techniques faces a basic inadequacy in the primary data.
The data on wind speed and direction are generally collected at airport loca-
tions and a few electricity-generating plants.  These locations are represen-
tative of flat terrain rather than rolling, or hilly or mountainous regions.
The erosive power of wind may be seriously underestimated by using published
                                                               2     '
data to predict wind erosion damage for sites as small as 10 km  and smaller
and a few kilometers distant, since the extreme wind speed is pertinent.
Horizontal extrapolation of wind speed for offsite predictions faces direc-
tional shear, turbulent discontinuities, and orographic deflection of unknown
magnitudes.
     Wind-energy distribution maps are being undertaken at this time and may
alleviate a degree of the risk in making horizontal extrapolations from the
site of measurement to the cleanup site.  These maps will be useful in flat
terrain under overcast conditions.  They are not available for generic use
unless the cleanup treatments are restricted to the vicinity of airports.
     Probably the best return in deciding what sites should be chosen as can-
didates for cleanup would come from installing remote wind recording equipment
                                     8-5

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               Wind erosion
          Soil moisture-Wind velocity factor
              Very low   [1110-10%
              Low

              Intermediate ["JJ 26-60%

              High      ££381-150%

              Very high   QH > 150%
Figure 8-2.
Surface soil  moisture-wind velocity  soil loss
factor as a  percent of soil  loss at  Garden City,
Kansas (marked by X)  (adapted  from Agricultural
Research Service^).
                               8-6

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          Figure 8-3.  Rainfall erosivity index, based on maximum
                       30-minute intensity, from an average of
                       annual maximums (from Wischmeierl?).
and precipitation recorders at the sites.   From onsite data general regres-
sions would be possible with the weather station network data.   Without onsite
data the predictions are worthless since they can be highly misrepresentative
of the site.
     Rainfall intensity is the factor detaching soil fragments  and allowing
runoff to carry them away.  The data summarized in Figure 8-3 represent a
portion of the work done by Wischmeier and his colleagues."  .One of their sum-
maries  has been widely used in erosion predictions.  Two reviews of erosion
dislocation mechanisms and of detachment by wind  and water   lay the basis
for the widely used "Universal Rainfall-Erosion Equation."  This is based on
the kinetic energy of the rainfall and the maximum 30-minute intensity of
the storm.  It must be used by trained staff for particular sites.
     Plant growth, precipitation and climate are interrelated variables that
determine the erosive force exerted upon soil from which sediments are derived.

                                     8-7

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A general  integration  for  all  these  factors  is  shown  in Figure 8-4.  That
precipitation regime transects the natural ecosystems upon which the agri-
culture discussed  in this  chapter draws.  These are the natural forces that
test the wisdom  in selection of cleanup treatment, when the choice is field-
tested at  a  site.



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Figure 8-4.  Idealized effective precipitation, vegetation, and sediment .yield
             on west to east transect (adapted from Bennett and Donahue8).

8.3  MAN-MADE PERTURBATIONS
     All agriculture is a man-made perturbation that functions as a production
system because of the energy added to change it from a natural ecosystem.  In
                                     8-8

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the context of this chapter the alleviation of natural perturbations on
cleanup areas is addressed.                                 •
     The ideal preventative of wind and water erosion is a layer of wetted,
attached mulch.  For semi-arid lands the procedures were derived after the
enormous dust storms of the late 1930s.  The amount of mulch needed varies
with soil texture and species of crop.   A summary of application rates for
deciduous forest agriculture is given in Table 8-2.  As shown there seedling
plants hold soil losses to those comparable to tonnage quantities of straw
and stover (fodder) residues.  Plant residues and seedling grasses are almost
universally used for wind and water erosion control.

          Table 8-2.  Effectiveness of ground cover on soil erosion
                      loss at construction sites in deciduous forest
                      zones.
          Ground cover
Soil loss relative
 to bare surfaces
     (percent)
          Established seedlings
            Permanent grasses
            Ryegrass (perennial)
            Ryegrass (annual)
            Small  grain
            Millet and sudangrass
            Field  bromegrass
          Grass sod
          Hay (5 tons per ha)
          Small grain straw (5 tons per ha)
          Corn residues (10 tons per ha)
          Wood chips (10 tons per ha)
          Asphalt  emulsion (310 gal per ha)
         1
         5
        10
         5
         5
         3
         1
         2
         2
         2
         6
         2
          (Adapted from Notes et al.11)
     Large amounts of surface runoff are generated by acreages of cropped
soils.   Need for runoff control is intensified where the soil is bared and
                                    8-9

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multiple treatments are rated for runoff control in Table 8-3.   These are
the kinds of combined treatments that are evaluated in Section 8,.6,  Quanti-
tative Assessments.

           Table 8-3.  Control systems and relative effectiveness.
     System
             Components
Percent effectiveness
       1.
       2.
       3.

       4.
Seed, fertilizer, straw mulch plus
erosion structures, normal
Same as (1) except chemical (12
months protection) replaces straw
Same as (1) except chemical straw
tack replaces asphalt
Seed, fertilizer, straw mulch with
diversion berms plus sediment basins
Seed, fertilizer, straw mulch; down-
stream sediment basin using flocculants
Same as (3) without straw mulch
Chemical (12 months protection) sedi-
ment basin using flocculants
Same as (4) with seed, fertilizer
         91

         90

         91

         90

         96.

         94
         94

         96
     (Adapted from Hotes et al.11)
8.3.1  Runoff and Fertilization
     Runoff does more than produce sedimentation.  It can strip away organic
matter and mulches.  The plant nutrients lost in this way are some of those
recommended for reseeded areas in Table 8-3.  These nutrient losses were
studied quantitatively on field plots in 1917 and included nitrogen, phos-
phorus, calcium, and sulfur.   A recent review on phosphorus   losses from
                                                                     14
vegetables fertilized with manure placed losses at 70 kg/ha per year.
This is much more than many farm programs call for in fertilization regimes.
                                                                      4
Seasonal variations are pronounced with three identified loss periods.    Most
of the nitrogen and phosphorus loss occurred when the plants were newly estab-
lished and correspond to plowing and soil cover treatments evaluated in Section
3.6.
                                    8-10

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     The 24 cleanup treatments are potential treatments for a variety of
soils and crops grown in the desert, grassland, or forest.  Representative
groupings of species for different purposes are shown in Table 8-4 with the
environment in which they are being produced.  A number of the contaminant
removal techniques include soil removal to a. specified depth and these depths
can be compared to the optimum root zone shown in Table 8-5 that each species
will permeate in deep soils.

8.3.2  Soil Compaction
     .The average density of weathered rock fragments in soil is approximately
2.5 times the density of water.  Taking the density of air as close to zero,
compared to rock, and a mixture of 50 percent air and 50 percent rock, the
average density of the mixture would be expected to be about 1.25 times that
of water.  For most soils with rock minerals as their principal ingredient,
the density is near 1.3.  In these soils there is a little more rock than
air if the density is judged from this discussion.
     Our hypothetical soil with 50 percent air would be a mass of small rock
fragments, with holes among the solid particles for the air.  The rock frag-
ments would not float because they are about 2.5 times heavier than water.
After a rain part of the air space is filled with water; in fact,the escape
of air can be seen where water is held on soil as in basin irrigation.  In
most soils the water wets the weathered rock particles and lubricates them
with the result that they slide across one another much easier wet than when
dry.
     The objective in compacting soils is to squeeze the particles close to-
gether so the volume occupied by the soil is smaller,  and the density is more
like rock than air.  When the density is near 1.5 to 1.7 plant roots do not
penetrate and plant growth is halted.   The water sprayed onto soil during
compaction is intended to lubricate the particles so they move across one
another under pressure from equipment.  A list of equipment and the depths
to which it compacts the root zone is given in Table 4-2 of Chapter 4.  These
are the depths to which the soil must be broken apart  for crop production if
the soils are intended for agriculture.
                                    8-11

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Table 8-4.  Commercial crop species in managed ecosystems.

Ecosystem Forage/pasture Row crops/field crops
Desert alfalfa/ladino clover sugar beets/dry farmed
dry beans/dry fanned
vegetables/dry farmed
Grasslands sweet clover/ fescues corn /winter wheat
alfalfa/wheatgrasses soybeans /spring wheat
home grass sorghum /barley
sugar beets/rye
Deciduous clovers/1 espedosa corn
forests timothy/bluegrass soybeans
tobacco
vegetabl
Table 8-5. Rooting depths of agricultural
soils.*
/spring wheat
/oats
es
crops in fertile,
Orchards
citrus
apricot
peach
household
plants
apple
pear
peach
deep, well drained

Use/species
Forage
alfalfa
sweetclover
clover
timothy
Pasture
ladino clover
fescue
wheat grass
brome grass
1 espedosa
blue grass
Row Crops
cotton
sugar beets
dry beans
corn
*Examples are irrigated
Rooting depth
observed
(meters)
3-4
3
1-2
1
0.5
1-2
3-4
1-2
1
0.5
1.5-3
1-2
1.6-1.8
2
Use/ species
Field Crops
wheat
barl ey
rye
oats
flax
Orchards
citrus
peach
apricot
apple
pear
Row Crops
sorghum
soybeans
tobacco
vegetables
Rooting depth
observed
(meters)
2-3
2-3
2-3
2
2
2-3
2
5
8-10
2
2-3
1.5-2
1-1.5
1-4
desert and tall-grass prairie.
                         8-12

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8.3.3  Compaction and Runoff
     Any description of hydrologic effects originating from clearing large
tracts of cultivated land and then resurfacing with an impervious layer de-
pends on having generic predictors available.  The net hydrologic effects
from resurfacing do have an area-dependent generic factor.  Intuitively, the
surface-storage of runoff is related to precipitation intensity and to local
topographic features.  Resurfacing a flat, downwardly concave area creates
runoff storage capacity that may enhance groundwater supplies locally, but
resurfacing the rolling topography that formerly supported deciduous forest
has variable outcomes that are directly dependent on the area involved.
     Flood water runoff on the northeastern belt of the former deciduous
forests of Ohio was most highly correlated with watershed area.  However,
there were two distinctly different area-dependent watershed classes, so
different that square kilometers of area drained was used as the criterion
for dividing the classes.  The zone separating the two flood classes was
           o
50 to 75 km .  Runoff volume correlated best with drainage area size, rain-
fall intensity, and soil infiltration rate.  These three variables were sig-
nificantly different from random correlates (probability of random correla-
tion being less than 1 percent for all three variables taken together or
individually).
     The effects of compacting soil on local runoff from micro-areas are
well known.  Examples are streets that require storm drains and diversion
structures, parking lots, building sites, and construction areas in general.
Bar-Kochba and Simon  rated infiltration rate into surface soil as the most
important non-climatic variable in their eastern Ohio study.  Reduction of
surface water infiltration rates has the obvious effect of increasing runoff
and reducing groundwater recharge rates.  This effect is less damaging upon
     2
10-km  areas in humid precipitation regions than in semi-arid zones where
agriculture depends on pumped water for crop production.  Thus, the effect
of a compacted area in restricting groundwater recharge increases as the hypo-
thetical compacted area is moved westerly along a decreasing precipitation
gradient.
                                    8-13

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8.3.4  Infiltration and Crops
     In an intensively studied area, eastern Ohio, the average water infil-
tration rate for grassed areas was more than twice the intake rate of adja-
cent row-cropped fields.   A soil-series-dependent influence on intake rate
was measurable but the relative infiltration rates were consistent among the
                                                      2
several soil series within the approximately 40,000-km  study area.  The
higher infiltration rate suggests why runoff is reduced and groundwater re-
charge increased by grass cover in deciduous forest agriculture.  Grass is
the preferred cover for drainage waterways because the stems reduce runoff
flow velocity and the abundant fibrous roots keep soil aggregates in place
against detachment.

8.4  EFFECTS OF CLEANUP PROCEDURES ON AGRICULTURE
     Qualitative descriptions of the effects that each of the different
cleanup treatments have on agricultural land are presented in this section.
The recovery of longer-lived agricultural crops to their precleanup produc-
tivity is briefly described in Section 8.5.  Quantitative assessment of the
impacts of cleanup treatments on agricultural systems is given in Section 8.6
in terms of the estimated times required for return to commercial productivity.
     The cleanup procedures described in this section have essentially three
different kinds of functions:  (1) treatments temporarily holding the con-
taminant in place, (2) treatments physically removing contaminants which
depend upon stabilization after the cleanup to prevent wind or rainfall ero-
sion until rehabilitation occurs, and (3) restriction of access into the
area by humans and animals.
     The projections made in this section are predicated on the information
which was available at the time the literature survey was completed.  Serious
revisions of these recommendations or rejections  of the projected  consequences
of the cleanup  in agricultural lands as more information is obtained appear
unlikely.  However, a number of publications will soon be available which are
indirectly related to cleanup techniques  in agricultural areas.   Surface min-
ing  in the Western states has resulted  in a great many techniques  being per-
formed for rehabilitation and reclamation of semi-arid and  arid lands.  These
techniques are  experimental  at present  and are being  evaluated for their

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effectiveness at the different sites involved in surface mining.  In a few
years these experimental methods will have been published in journals which
carry reports of experimental research, and subsequently they will be in-
corporated into books and reports that will be of use to individuals con-
cerned with agricultural land cleanup after a contaminating event.  An ;exam-
ple of the kind of material to be anticipated from surface mining rehabili-
tation is the statement in the recently released operating handbook published
by Coal Age.  This handbook stated in its Foreword:
          This Coal Age operating handbook of underground mining
          is the first of a series of books planned to cover key
          areas of present day coal mining operations.  Future books
          in this series will cover strip mining and reclamation,*
          coal preparation, management, and maintenance"]
     As noted in Section 8.1 the agricultural areas described as impacted
represent the irrigated southwestern desert, the short grass irrigated and
dryland agriculture on the west side of the American prairies and grasslands,
and from the midcontinent east to the northeastern middle-west of the United
States formerly covered by hardwoods and river bottom deciduous forests.
The desert area represents a transect across the American Southwest, extend-
ing east from the Imperial Valley of California to those irrigated parts of
New Mexico and southwest Texas.
     The impact of the cleanup treatments on domestic animals is not covered
here.  It is presumed that rehabilitation of contaminated areas for produc-
tion of agricultural crops is a prerequisite to any animal husbandry enter-
prises.  The general crops for which cleanup impacts are described generally
fall within three groups of cultivars:  (1)  dryland and irrigated forage
crops, (2) commonly produced row crops and small grains, and (3) tree crops
ranging from the citrus orchards of the irrigated desert to the stone fruit
and pome orchards in originally deciduous forest areas.

     CO-1)  Natural Rehabilitation
     Unlike natural ecosystems, agricultural ecosystems have no capacity to
replace the destroyed commercial crop by the same species after cleanup.
Since agricultural crops are grown at an energy cost, when this energy is
*Emphasis added.
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no longer supplied to the system the crops will no longer grow in commer-
cially productive quantities.  Waiting for natural rehabilitation to replace
an agricultural crop is an unacceptable procedure.  The time course of re-
turn from agricultural to natural ecosystems (Old Field Studies) has been
defined in Chapters 1, 2, and 3 under the heading Man Made Perturbations.
Further details for recovery sequences are in each of those chapters in
sections headed Recovery after Cleanup.  Those descriptions should be re-
viewed before forecasting the vegetational changes that will occur on aban-
doned farmland.  Ecologic journals are replete with flora succession studies
conducted on Old Field farmlands; they do not return to cultivars.

     (1-1)  Chem-leal S-tdb-Jt-izat-ion
     Containing the contaminant to diminish its redistribution has an imme-
diate and obvious benefit in both hazard reduction and in minimizing the size
of the area of ecological impact by later cleanup methods.  The function of
chemical stabilization in an agricultural system is to prevent redistribution
of the deposited contaminant.  More than seventy stabilizers are reviewed in
Appendix A; those suitable for use in agricultural fields have been desig-
nated in Table A-l.  With the exception of water-soluble emulsions, applica-
tion of a preferred chemical stabilizer requires a number of preparatory
steps before the field can be treated.  The area to be treated must be cleared
of vegetation or clearcut, stumped, and grubbed for tree crops, the slash and
vegetative refuse removed, and the fields smoothed and either graded or shal-
low plowed.  Most of the "preferred" stabilizers require direct mixing with
friable soils before they become effective in preventing resuspension of soil
and contaminant particles.  Because of this requirement for similar pretreat-
ment, the after effects from most of the chemical stabilizers will be very
similar on the farmlands treated.
     Chemical stabilizers which deflocculate soil particles, such as sodium.
chloride, sodium hydroxide, sodium carbonate, and Ca.lgon, are unsuitable for
use in western agricultural fields.  Although this class of alkaline and high-
sodium dispersants would stabilize surface soil, they can only be used in
areas which have high  levels of precipitation or access to free water in basin
irrigation.  The requirement for large amounts of water is to assist plants
in withstanding the effects of the saline soil that would be produced by these
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stabilizers.  Leaching of the soil for a long period of time before green
manure crops would compound the damage these stabilizers produce by removing
free salts, resulting in the deflocculated smrface soil becoming impervious
to water infiltration.  Sodium adsorbed on clay disperses mineral particles
and prevents water infiltration.  Lack of soil moisture prevents subsequent
plant growth.  Growth of plants prior to extensive water leaching has been
found the simplest way to remove the effects of sodium deflocculants and
reconstruct soil tilth.  Surface incorporation of high quantities of organic
matter into the soil is mandatory at the time recovery is instituted.  Crop
residues from plants produced for organic matter (green manure), or addition
of mulch which is worked into the surface soil are standard procedures.
     Thirty-six "preferred" stabilizers for agricultural  use are listed in
Appendix A; 29 of these require reseeding or replanting of the crops to which
they are applied.  The remaining seven would not destroy the crop to which
the stabilizer was applied.  Appendix A has an additional list of 22 "accept-
able" stabilizers that are acceptable as alternates for use when the pre-
ferred stabilizer cannot be used.
     Only 9 of the 58 stabilizers can be applied directly on growing crops
without totally endangering their commercial value.  Two of the nine plant-
safe stabilizers require special handling for cropland application; three
of the nine that are safe for plants are  water emulsions of asphalt or
resin, and four are colloidal suspensions of protein.

     (2-2)  Clearcutting Vegetation
     Clearcutting orchards has the same effect as clearing coniferous and
deciduous forests insofar as crop production is concerned.  It is very
improbable that the operators of commercial orchards would depend on stump
sprouting, for those species in which it occurs, as a method of creating
a replacement orchard.  It is more likely that the trees would be removed
in toto (treatment 1-3).  Clearcutting of irrigated and nonirrigated for-
age is the normal harvesting procedures and would have no significant im-
pact in cleanup considerations.
     Row crops would be eliminated by Clearcutting if undertaken before the
normal harvest time.  Clearcutting is the method of harvest for a number of

                                    8-17

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row crops.  Examples are machine-harvested tomatoes, combine harvesting of
all the small grains, the harvesting of the various species of maize and
sorghums, and the mechanical picking of cotton crops.
     The physical structure of agricultural soils would be unaffected by
this treatment.  Organic matter content would be undisturbed and the fer-
tility levels unchanged.  There would be no change in the suitability of
seed beds for subsequent crop production.

     (1-3)-  Stumping and Grubbing
     With the exception of orchards, this treatment is inappropriate for
agricultural crops.  The effects of stump chippers and root rakes on east-
ern orchards would be similar to the effects described for deciduous forests
(Section 3.4).  This technique would, of course, eliminate any productive
capacity of an orchard by eliminating the producing plants.
     The physical effects on the soils in the eastern United States would
be due primarily to mixing the fertile surface layers with the relatively
infertile subsoil layers which the new tree roots would normally penetrate.
For desert orchard soils, there would be a small increase in fertility of
the lower segments of the profile and little decrease in fertility of the
upper parts of the profile,  Irrigated desert citrus would be eliminated
as a crop, but the effects upon the soil structure would be relatively mild
for most undeveloped irrigated desert soils.  The principal post-cleanup
effects would be the reduction in the fertility of the profile utilized in
the new mixed soil surface.  This would need correction before reestablish-
ing orchards in the eastern United States.  A secondary impact on eastern
orchards would be displacement of wildlife from hedgerows and fencelines
surrounding the orchards.  The measure of any economic impact would be the
potential for a reduction in production of those crops dependent upon dis-
placed animals for pollination.

     (1-4)  Scraping and Grading
     The consequences of surface scraping and grading upon any agricultural
crop is seasonally dependent.  Performing this operation when fields have
been harvested and are normally clear of crops would result in removal of
                                     8-18

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 substantial  portions  of the limited  organic  matter  in the  desert,   it  would••--'•;-
 have essentially no effect  in the grassland  areas but clearcutting  would make
 it  be an extreme perturbation in  eastern  orchard areas and on  any of the grow-
 ing eastern  row crops.   Surface soil  would be  laid  bare to wind  and water  ero-
 sion.   If the  soil were moist at  the  time of scraping and  grading Cpresumably
 by  heavy equipment such as  road graders,  land  scrapers,  and bulldozers), sig-
 nificant compaction would be  likely  to result  (the  effects of  soil  compaction
 are described  in cleanup treatments  2-3,  2-4,  and 2-5).
      The physical-chemical  properties of  most  agricultural soils would not
 be  greatly changed by scraping and grading (excluding compaction effects).
 The principal  effects would be increased  susceptibility to wind or  water ero-
 sion at  the  loosened  surface.  However, there  would be little  opportunity for
 excess  sedimentation  since  the basic  runoff  water diversion structures would
 be  unchanged.

      (1-5)  Shallow Plowing
     Shallow plowing  would  eliminate  an unharvested cultivated crop and, if
 the  crop were near maturity, would create a  trashy surface.  In the noncrop-
 ping season  its  impact would be minimal or insignificant since plowing is a
 normal operation of agriculture.   Plowing with disc equipment would have lit-
 tle  impact on standing orchards in either irrigated or rainfed agriculture.
 The most likely  effect would be soil compaction in the wheel tracks, and fur-
 row bottoms resulting from the use of plowshare equipment,  if the soil were
 significantly moist at the time operations were carried out.
     The effects overturning the plow layer has on the seed sources, vegeta-
 tion, and soil erosion processes of semi-arid rangeland sods-are overcome in
one or two seasons of regrowth.  Shallow plowing of less than 10 cm has little
 impact on survival of grasses but  afterward the roughened  surface is unsuit-
able for stabilizing by mechanical compaction because the  surface is trashy.
Clays and deflocculants would fall among the sod chunks and be lost  to subse-
quent stabilization techniques.
     Runoff is reduced by the increase of surface storage  in the roughened
area but groundwater recharge in the western shortgrass prairie would be un-
changed because the subsoils are permanently dry.  Surface erosion by wind

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and water would be unchanged as grass cover is the cure recommended for both
erosion mechanisms.
     Damage to woody plants is of short duration.   Seed stocks would remain
and stump and root sprouts would soon revegetate the plowed rangeland.   Ani-
mal grazing on the new growth may be a problem in establishing regrowth.

     (1-6)  Deep Plowing
     Plowing to a depth of 40 cm would entirely disrupt any of the agricul-
tural crops during their growing season.  If the land were fallow, it would
eradicate standing orchards, pastures, and rangelands.  The fallow season im-
pact in areas with row crops and small grains would be relatively small and
approximately analogous to the consequences of shallow plowing (treatment 1-5).
Its effect in pastures and rangelands would be a reduction in productivity
of one or more growing seasons.  On shallow profiles in the short grass prai-
ries it is likely to produce a mixing of the A- and B-horizons, reducing plant
growth in subsequent seasons unless fertilization, and possibly reseeding in
the drier areas (less than 35 cm mean annual precipitation), is carried out.

     (1-7)  Soil Cover Less than 25 cm
     The significance of the impact on agricultural crops is a direct function
of the quality of the soil used for the cover.  A soil high in clay would sig-
nificantly impair aeration in orchard crops and production decline would begin
in a few months.  Attempts to add soil to areas with row crops would be im-
practical in terms of attempting to save the crop from the equipment.  The
minimum impact would occur in those areas which are grassed—either rangelands
or irrigated grasses.  Sweetclover forages would probably survive but the sur-
vival of  irrigated forages, such as alfalfa and ladino clover, is uncertain.
The basic soil fertility  in the root  zone would be unchanged by this depth of
cover.  The principal effects on seed bed  suitability  for cropping would be
fertility changes  from the soil added.  The soil used  for covering would prob-
ably not  be equal  in tilth and fertility to the soil  it covers up.

      (1-8)  Soil Cover 25 to 100 am
      It  is improbable that commercial agricultural  crops would survive the
addition  of a  soil cover  of this depth.
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     (.2-1)  Remove Plow Layer
     This layer is about the minimum depth that can be removed as a controlled
cut by ordinary heavy earthmoving equipment.  Soil removal would create a
radical disturbance in agricultural land, almost regardless of the crops that
were involved.  It would totally destroy rangeland grasses, forage crops,
irrigated forage crops, small grains, and standing tree crops normally found
in orchards.  It would represent an especially severe disturbance east of the
2-cm -runoff isogram (Figure 8-1).   In the short grass prairie this treatment
accomplishes complete removal of the A- and a substantial part of the B-horizon
with the corresponding loss of the normal organic accumulation upon which the
fertility of the land is based.  Removal of the organically rich A-horizon in
this area would leave the soil with a severe nitrogen deficit.
     It is unlikely that any of the standing orchard species would survive
removal of the surface 6 inches of soil in the long term, outside of irrigated
areas.   Minimum effect would be anticipated in those deep-lying desert soils
that are normally irrigated for crop production.  These generally coarse-
textured soils allow a more rapid deep penetration of plant nutrients from
surface and shallow subsoil applications into the soil profile than occurs
with nonirrigated agriculture.  However, removal of this layer in irrigated
agriculture would destroy row crops produced there.

     (2-2)  Remove Shallow Root Zone
     On the shallower soils, removal of up to 40 cm of soil profile would
eliminate the fertilized root zone where the major dry-farmed crops are grown
(i.e.,  the infertile and highly calcareous regions of the short grass prairie  •
and in some of the caliche areas underlying irrigated deserts).  The resulting
truncated soil profile would more nearly resemble an unpaved roadway after
deep cuts to maintain a uniform grade in hilly terrain. • Shallow root zone
removal in the tall grass prairies would have relatively little effect since
the profile would still contain significant depth and amounts of organic mat-
ter below the soil cut away.  In crop lands formerly occupied by deciduous
forests, this treatment would destroy the agricultural potential of many of
the farmed areas,  eradicating the entire organic matter content of those soil
profiles as well as any residual artificial fertility elements applied to pro-
mote production of crops.  The phosphate-rich plow layer would be removed and
the surface remaining would be more suitable for nonagricultural purposes.
                                     8-21

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     Prevention of erosion is the immediate problem in soil management when
the root zone has been stripped to a depth of 40 cm.  West of the 2-cm runoff
isogram surfaces not naturally compacted or cemented are vulnerable to wind
erosion.  East of the 2-cm isogram, post-cleanup surface erosion by runoff
water would be a severe problem throughout the stripped areas.  Uniformly
removing 40 cm of soil surface would impair runoff diversion structures nor-
mally incorporated into farmlands.  Removal of the shallow root zone west of
the 2-cm runoff isogram would leave a smooth erodible surface in the place
of the roughened trashy surface normally utilized to prevent wind erosion;
that is, planting ridges, grass waterways, lister ridges, shallow terraces,
and the basic contour structures would be removed.  The basic contour struc-
ture could be maintained if care were taken during the soil stripping to take
the soil along field contours previously constructed for dry farming and
irrigation.
     The most severe impact in the excavated agricultural areas would be soil
erosion.  Other serious impacts relate to crop production, i.e., loss of the
soil organic matter, and hence loss of soil fertility.

     (2-3)   Remove Scraping and Grading, Mechanically Stabilize
     This treatment would have little impact on the internal structures nor-
roal to control of overland water flovf in agriculture.  The dikes, berms,
drainage ditches, grassed waterways, and overfall structures normally present
would be devegetated but not basically eradicated.  Scraping and grading on
grasslands in pasture- and rangelands would remove the surface organic matter
layer, subsequently reducing nitrogen availability in the grasslands.  The
principal consequence would be reduction of sedimentation onto lands adjoin-
ing the cleaned up area.  Scraping and grading, removing the loosened mate-
                                                            2
rial, and stabilizing the surface in areas as large as 10 km  would signifi-
cantly reduce sediment loss that would otherwise occur from scraping and
grading large areas.
     The effects of this treatment and removal of deeper layers of soil to
40 cm were previously described in cleanup treatments 2-1 and 2-2.
     The basic physical effects of this cleanup treatment on desert, grass-
land, and crops grown on the formerly deciduous forest lands have been de-
scribed in Chapters 1.4, 2.4, and 3.4  (under cleanup treatment 2-3) to which
                                    8-22

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 the reader is referred for added detail.  The effects and probabilities of
 wind erosion and runoff erosion by surface flow are discussed there and are
 not repeated here.  The descriptions in Chapter 2 (Prairies) are especially
 pertinent to cleanup in areas producing grasses under dryland conditions and
 for both native and reseeded vegetation on rangelands.
      The number of mechanical stabilization procedures that can be used in
 agricultural areas to be returned to croplands is limited.  The slopes in
 cropped areas are not usually steep enough to require that meshes, nettings,
 or plastic films be laid in the areas involved.   Furthermore, the areas; to
 be protected in farmed fields may be so large that substantial problems would
 arise from attempts to use plastic films as covers.   In a relatively short
 time the plastic would rip and tear and lose its effectiveness in containing
 contamination.   The otherwise usable mechanical  stabilizations would subse-
 quently require removal of an additional layer of soil because they are
 variations of the compaction process.
      The success of compaction methodology is directly dependent  on the
 amount  of clay in the soil which is compacted.   It is unsuccessful in the
 coarse-textured,  sandy soils frequently found in the  irrigated desert where
 reduction of pore space will be sufficient to destroy agricultural crops.
 Removal of shallow soil and mechanical  stabilization  by compaction in an
 orchard would kill  the trees in a  short time  due to the combined  effects  of
 poor aeration and severe moisture  deficits brought about  by  preventing pre-
 cipitation infiltrating into the soil profile of the  orchard.   If there is
 enough  clay in  the  surface soil  for compaction to  be  effective, compaction
 would be relatively permanent in agricultural terms.   Return of the area  to
 agricultural  productivity  would  require rippers,  subsoil  chisels,  repeated
 plowing,  and  other  action  to break  apart the  compacted layer and  free the
^oil aggregates  from the effects of prior  compression.  The  offsite surface
 flow of runoff would have  a major  impact on adjacent  areas.   For  areas  as
 large as 10 km  ,  uncontrolled runoff could be a  significant  factor  down-
 stream.   It is also  probable  that there  would be a drastic reduction  of the
                                  2
 groundwater in an area  where  10  km  was  mechanically  compacted  for  stabili-
 zation  purposes.   It  is unlikely that deflocculants such as  sodium  chloride
 would be  tolerated  for  lands  that were to  be  returned  to agricultural pro-
 duction,  so mechanical  stabilization or  short-term chemicals  are needed.
                                    8-23

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     (2-4)  Remove Plow Layer-} Mechanically Stabilize   '                  .
     The physical effects on the suitability of the cleaned-up area for agri-
cultural crops under this cleanup treatment are essentially the same as those
described under cleanup treatment 2-1.  The effects of mechanical stabiliza-
tion would be very similar to those described in treatment 2-3.  The princi-
pal differences relate to changes in organic matter and soil fertility induced
by compaction. .Where there is a relatively high water table and a high or-
ganic matter content below the compacted area (e.g., from a large root mass),
the fields would be subject to anaerobic decomposition of the organic matter
and the nitrogen would be reduced to ammonia forms with the potential for its
slow volatilization out of the soil profile.  Effectively, the nitrogen con-
tent of the cropland would be reduced compared to that which existed prior
to the cleanup, as in treatment 2-3.  Crop production could not be resumed
until the compacted area had been broken apart by mechanical means.

     (2-5)  Remove Shallow Root Zone, Mechanieal~iy Stabilize
     The effects of this treatment, insofar as agricultural use of-the land
is concerned, are very similar to those for plow layer and shallow root zone
removal.  Soil fertility would be reduced more than with removal of the plow
layer.  The deeper truncation of the soil profile would render revegetation
of the rangcland or native pastures unlikely without renovation in the semi-
arid short grass prairie region.  The desert soils on alluvial fans and
deeper profiles would be least affected by this treatment.  The deeper cut-
ting is likely to have significant effects on surface runoff control struc-
tures in the sub-humid and humid agricultural regions.  These control and
diversion structures would have to be reinstituted before surface stabiliza-
tion was undertaken if severe erosion effects are to be avoided.  The same
soil preparation methodology as described for treatments 2-3 and 2-4 would
have to be undertaken to neutralize soil compaction disadvantages prior to
reestablishing agricultural production.

     (2-6)  Remove Scraping and Grading,, Chemically Stabilize
     The physical effects upon agricultural production from this .treatment
are about the same as the combined  effects of cleanup treatments 1-4 and  2-3.
The effects of chemical stabilization would, not be as. long-lasting as the

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 mechanical  stabilizing  treatments,  and  in  a number  of  cases  immediate reveg-
 etation with some  variety of the grasses is required where runoff may cause
 surface erosion.   Infiltration  into the soil profile is  controlled by the
 soil profile physical and chemical  characteristics  rather than by the chemi-
 cal stabilizer  applied;  hence,  it is unaffected by  this  treatment.
     The most suitable  chemical  stabilizers to use  in  an agricultural area
 are those which break down without  leaving toxic residues that would impair
 food values  or  plant growth  at  a later  time.  Some  of  the chemical stabili-
 zers described  in  treatment  1-1  would be the stabilizers of  choice in this
 treatment also.

     (2-7)  Remove Plow Layer, ChemJoally  Stabilize
     This is  a  composite  technique  described separately  under treatments 1-4
 and 2-6.  The overall consequence is one of reduced soil fertility with seed
 bed conditions  less suitable  for reintroduction of agricultural crops than
 those conditions resulting from  treatment  2-6.

     (2-8)  Remove Shallow Root  Zone, Chemically Stabilize
     Slicing  away the surface profile to a depth of approximately 40 cm would
 require  the greatest application  of chemical stabilizers.  Loss of the or-
 ganic debris  leaves the grassland soils susceptible to wind erosion,  and re-
 quires immediate reseeding with  grasses to stabilize the soil against runoff
 in sub-humid  to humid regions.   Removal of the loosened  soil minimizes sedi-
mentation problems downstream in the runoff area but increases flooding po-
tential  from  runoff out of areas as large as 1 to 10 km2.

     (3-1)  Barriers to Exclude People
     The most effective fencing for the exclusion of people would be  a chain
 link fence 6 to 10 feet high posing a physical restraint to trespassers.

     (3-2)  Barriers to Exclude Large Animals
     Design of fences to restrain cattle is a well developed technology.  Re-
 straining of  large game animals, such as elk and moose,  is not likely to be
a problem in most agriculturally developed areas.   Preservation of mechani-
cally and chemically stabilized surfaces would require  that large animal

                                    8-25

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traffic be restricted.  The hooves of domestic cattle and sheep would rapidly
break down either of the stabilized surfaces, especially since the animals
are prone to travel single file which concentrates the cutting action of the
hooves in a small path.

     (3-3)  Barriers to Exalude Large and Small Animals
     Attempts to eliminate small burrowing animals, such as ground squirrels
and gophers, would probably not be successful in large areas.  Containment
of these animals within the area would be more successful than elimination.
Consequently, fencing should be directed towards retention of animals pre-
sumed to have become contaminated in the area rather than to keep small mam-
mals out of the area.  Horizontally oriented small-mesh fencing in ditches
around the cleaned-up area and backfilling to provide a mesh ledge will pre-
vent the escape of both large and small burrowing animals.  Because these
animals have a relatively limited home range there is not much danger of
them transporting large quantities of contaminants significant distances.
Fencing of successive containment areas may be the most practical method to
deal with burrowing animals.  It is assumed that-larger animals can be suc-
cessfully excluded from contaminated areas until the appropriate cleanup
treatment has been selected for the area.

     (4-1)  Asphalt Hard-Surface Stdb-Llizat-ion
     Consideration of the use of this treatment  in an agricultural area
should be based on the understanding that it will be a very temporary cover.
Since the surface in most: agricultural areas will inevitably be disrupted
by stray cattle at some time soon after the material is  laid down, it cannot
be considered to be a permanent way of securing  a contaminant.  In areas
where surface soil experiences freezing and  thawing, such as the  grassland
and deciduous forest  areas, frost heaving is  likely  to be highly  destructive
to an asphalted or road-oil treated area in  a relatively few seasons.
     Application of hot road oil  or asphalt  to an  existing crop in agricul-
tural production would be  disastrous.   In most circumstances the  standing
agricultural  crop  would be removed, with the possible  exception of tree
crops.  An  agricultural crop must be  considered a  total  loss if the  appli-
cation  of asphalt  or  hot  road  oil is  necessary to  hold the contaminant  in
                                     8-26

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place until  subsequent cleanup treatments are undertaken.  Few agricultural
crops can resprout and puncture heavy asphalt surfacing.  The more damaging
effects would include compression tracks introduced by the heavy equipment
needed for transporting asphalt or hot road oil across the areas to be
treated.  Reclamation of the sites will be an extremely expensive process
since the oil-soaked or asphalt layers must be removed before agricultural
production can be resumed.

     (4-2)  Concrete Hard-Surfaoe Stabilization
     This is the most severe cleanup treatment proposed for use in agricul-
tural areas.  The expense of removing the concrete at a later date almost
entirely eliminates use of this cover from consideration.  It is inappropri-
                                           "2
ate for use in areas as large as 1 to 10 km .  The transportation costs of
recovering and disposing of the large amount of concrete that would be re-
quired for even 0.01 km  is almost certain to eliminate it from serious con-
sideration in areas where agriculture is to be resumed.

    . (5-0)  Application of Sewage Sludge
     The properties of urban sludge are significantly different from farm
manures and crop residues.  The use of sludge requires highly specialized
information in agricultural management practices.  Outright recommendations
for the application of sludge are unsafe.  Urban sludge is still suspected
of containing viable viruses and must not be allowed to come into direct
contact with the edible portions of plants.
     Sludge contains high quantities of industrial wastes at times.   Such
wastes contain heavy metals which are poisonous to man:  lead, cadmium,
chromium,  copper, and nickel.  Other elements hazardous to man (unless proper
soil management practices are used)  are aluminum in various compounds, ar-
senic,  selenium, antimony, and mercury.   Wastes from industrial electroplat-
ing processes are extremely high in these particular metals.

     Sludge supplies moderate amounts of nitrogen to cropland and increases
the organic matter content of soils.   Sludge application is not safe for
crops grown on acid soils of the former deciduous forest areas for either
human consumption*or as animal, feeds.  However,  the low solubility of the

                                    8-27

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heavy metal elements in neutral and alkaline soils minimizes these hazards.
Sludges contain from 1 to 6 percent nitrogen on a dry-weight basis.   Moder-
ate amounts of sludge would supply nitrogen to croplands and significantly
increase the organic matter content of the soil.  Five to 40 tons of dry
matter per hectare will supply nitrogen and organic matter in the alkaline
grassland and desert soils.  A decay series worked out for breakdown of the
organically contained nitrogen indicates that approximately 25 percent of
the nitrogen will be available to plants in the first four years the sludge
is in the field.  Approximately 30 to 60 percent of the nitrogen in the
sludge is in an inorganic form and would be readily available to plants in
the first year after the sludge application.  This soluble nitrogen poses
a potential hazard to groundwater supplies.  For this reason, large excesses
of sludge should not be applied in renewing the organic content of soils
following soil removal, scraping and grading of desert soils, or the addi-
tion of soil covers at a depth of 25 to 100 cm over croplands.

     (6-1)  High Pressure Washing (<3 mm)
     This cleanup treatment is outside the scope of work for this report.

     (6-2)  Flooding to SO am
     One-time flooding for redistribution of the contaminant into the soil
profile is outside the scope of work for this report.

     (7-0)  Soil Amendments Added
     Experiments in which a variety of materials have been added to soils
for the purpose of preventing plant uptake of hazardous material have been
unsuccessful.  Contaminants that are adsorbed onto the exchange surfaces
of soil minerals become available to plants either by contact exchange be-
tween the mineral surface and the root or by normal  solution processes.
Once a contaminant  is no longer retained on the surface  soil but has,  in
fact, penetrated the root  zone of agricultural  crops, the  suggested reclama-
tion procedure  is one of management that will produce  luxuriant vegetative
growth that  is  discarded.  This is accomplished by normal  management  prac-
tice,  soil  liming where needed in  the  deciduous area,  and  large  additions
of nitrogen,  potassium and phosphate  to  promote luxuriant  plant  growth where

                                    8-28

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 water supplies are adequate.  In the prairie and desert areas the limiting
 factor in land reclamation is the water supply.  Attempts to immobilize
 heavy metals to avoid plant uptake in the deciduous area have been unsuc-
 cessful.   Breakdown of the sludge releases nitrates, sulfates, and other
 acid forms which will readily consume the added lime and result in highly
 acid soils from which plants readily extract the injurious metals cpntained
 in the sludge.

 8.5  RECOVERY FOLLOWING CLEANUP
 8.5.1  Irreversible Changes
      The  complement of cleanup techniques discussed in this report has  no
 irreversible changes.   The limits to recovery of croplands are economic;  the
 question  is  whether to rehabilitate  the spill area,  soils, and crops.  The
 limits to the use  of the most  damaging  cleanup practices,  asphalt (treatment
 4-1)  and  concrete  (treatment 4-2), are  the cost and  effort required to  in-
 stall the asphalt/concrete cover  and remove it later.   The soils  under  these
 two hard  surfaces  are  damaged  more by compaction than  by seepage  of chemi-
 cals.   Compaction  can  be rectified mechanically,  as  highway reconstruction
 and relocation have shown.

 8.5.2  Rates  of  Recovery
      In this  chapter all the cropping systems  that are  discussed  have been
 created by energy  input  by man.  The rates  of  recovery  from  cleanup are
 directly  proportional  to the energy  input  expended for  rehabilitation in
 agricultural  systems.  None of the agricultural  systems described will re-
 habilitate themselves  to commercially viable  levels once cleanup has been
 performed.  Agricultural systems do not follow  the concept of species suc-
 cession through intermediate stages to climax as described in Appendix B
 for natural ecosystems.  They follow the growth, pattern of one individual
plant.
     Few of the environmental insults that may have extremely large impacts
 in natural systems would have significant impacts in nonorchard agricultural
systems.  Agricultural systems normally have structures appropriate for con-
trol of erosion by wind or water runoff.  The suggested cleanup treatments
need not destroy structures.
                                    8-29

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     Rangeland and pasture grasses would need reseeding and modest nitrogen
fertilization to recover their productivity.  Precipitation controls the
rate of recovery to be expected.  Unusually intense rainfall would float
the seed away and drought would kill the seedlings after germination.  In
normal weather, productivity on rainfed land is regained in 2 to 3 growing
seasons.
     Row crops, small grains, and field crops would need the same management
they are given each season for normal productivity.  The same recovery scheme
is appropriate to nontree irrigated crops.  Land leveling for irrigation is
more severe than any of the recommended cleanup techniques; only mechanical
stabilization and asphalt/concrete resurfacing are more disturbing than re-
sloping a field for irrigation.
     Orchards would require replanting after any but cleanup treatments 1-1,
5-0, and 7-0.  First fruit bearing would begin in 5 to 6 years and full pro-
duction by 10 to 12 years, including citrus.
     The general case for recovery of row crops, small grains, irrigated,
and rainfed pastures follows the  sequence imposed by natural disasters  such
as drought, fire, or flooding.  Tree orchards  likewise have as their recov-
ery model the growth and management steps that would follow renovation  of
an old, declining orchard.

8.6  QUANTITATIVE ASSESSMENT OF CLEANUP  IMPACTS
     The impact assessment assumes  in cleanup  treatments that the contaminant
is on  the  surface  soil  initially, and that  clearcutting  is carried out  before
any of the other temporary containment  and  removal  measures  (1-3  through 2-2,
2-3 through  2-8, and 4-1  and 4-2) are performed.   Tree crops are  assumed to
be  entirely  removed prior to  soil manipulation,  including  root  removal  (treat-
ment  1-3) .
      All erosion  control  devices  for  runoff are  expected to remain functional
 in the eastern hardwood croplands.
      The  impacts  in this chapter  require the intervention of man in almost
 all cases  after a cleanup treatment has been performed.   The multitude of
 corrective actions possible with four kinds of crops (forages and pasture,
 row crops,  small  grains,  and citrus,  stonefruit  and pome orchards), 24 cleanup
                                     8-30

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techniques, and three ecosystems (desert, grassland, and deciduous forest)
requires that the impact analysis be general and easily reproduced.  To that
end the impact indexing system is shown here for reference.
     Response Required to Resume Production
       No measurable impact, no correction needed
       Loss ends with crop directly exposed to contaminant
       Restored by normal agricultural practice for that crop
       One renovating technique required for crop next year**
       Two renovating techniques required for crop next year**
       Three or more renovating techniques required for crop
       next year**
       Renovation restores crop production in second growing
       season**
       Greater than 5 seasons for commercial crop
       Greater than 10 seasons for commercial crop
 Index
Number*
  0
  1
  2
  3
  4
  6
  7
  8
     The soil profile and climatic variables for pasture and grassed range
are discussed in Chapter 2.6.  Removing 40 cm of soil on the Rocky Mountain
side of the shortgrass prairie cuts into the alkaline B-horizons.  In that
region natural precipitation is too low for maize and orchards.  On the Iowa
side of the grasslands revegetation will recover almost spontaneously in
rainfed pastures.
     Cleanup techniques that are similar in impact intensity to normal farm-
ing are mowing (1-2) forage and pastures; shallow plowing (1-5) and scraping
and grading (1-4, 2-1) are similar to land leveling and are readily erased
by the usual seed bed preparation in row crops; and small grains.  Trees are
entirely traumatized by clearcutting (1-2); thus stumping and grubbing and
subsequent operations have no additional effect on the tree crop.  Trees in
orchards in the broad sense are totally destroyed by cleanup.  They survive
 *A11 treatments requiring unusual treatments for regaining productivity are
  equivalent to conditionally retrogressive (Index Number = N+2).
**Renovating techniques are early reseeding, early transplants, annual fer-
  tilizer additions, mulching, unusual irrigation, reterracing, recontouring,
  and other substantial, unusual treatments such as early summer defoliation
  of orchards.
                                    8-31

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contamination retention processes and soil amendment but not any of the
standard decontamination procedures where soil is moved about.
     No significant physical impact on the land occurs when barriers (3-0)
are used, but the economic impact caused to the owner by lack of resource
availability may be severe.  This is true in all the systems reviewed and
for normal fertilization (7-0).  Recommended chemical stabilizers (1-1) have
a similar impact across the species and soils and cause the loss of the
standing contaminated crop from the sprays and machinery used in the fields.
Clearcutting (1-1) forage and pastures is ordinary mowing and likewise costs
one cutting of one crop.  On row crops the entire crop seasons' product is
lost from clearcutting (1-1) unless it occurs at harvest time.  Sludge ap-
plications (5-0) are risky and surface applications are limited to fields
that grow animal feeds or to citrus orchards if injected into the subsoil.
     Rendering the surface impervious to precipitation entry has two effects,
deficits in subsurface stored water and downstream channel flooding, whether
it is accomplished by soil compaction (treatments 2-3, 2-4, and 2-5) or by
paving (treatments 4-1 and 4-2).  Groundwater in the treated zone is cut off
from local recharge and channel flow becomes proportional to the incidence,
intensity, and duration of precipitation once the surface threshold for wet-
ting is reached.   Erosion control structures would need to be maintained on
all far^s to handle the increased runoff from soil stabilizers.
     Loosening the surface soil by plowing (1-5, 1-6) and using soil covers
(1-7, 1-8) can lead to enormous runoff erosion losses but are otherwise non-
traumatic to forage, pastures, and small grains.  Land leveling fills is
similar to treatment 1-4, and erosion control terracing and contouring fields
are analogous to treatment 1-8.
     Hardsurfacing treatments (4-1 and 4-2) are likely to be acceptable on
a few acres if they are removed later or the land is condemned.  The concrete
or asphalt residues are not especially harmful to plants where they have been
mixed with the soil.  Removal of slabs might be expensive but hard surfacing
has features of, retention that other treatments lack.
     No treatments were judged entirely prohibited on a reclamation basis,
except some chemical stabilizers.
                                    8-32

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     Successful soil compaction increases runoff from rainfall to high per-
centages.  The proportion may increase to three-quarters of the local pre-
                                                                          2
cipitation, and downstream flooding is assured in areas as large as 1.0-km .
The degree of success in compaction sets the magnitude of impact afterward
for degrees of hazard.  An effective resurfacing depends on low organic
matter content in the soil and high clay.  These are soil characteristics
of the deciduous forest agricultural areas.  Cleanup treatments 2-3, 2-4,
and 2-5 have been given consistently high recovery time indices in ail non-
tree crops in deciduous areas, and lesser impact recovery time indices in
prairie.  Mechanical compaction is impaired in prairie fields by the high
organic matter residue in the profile, even if 40 cm of topsoil is removed
as in treatment 2-5.
     Lands in crops will have basic erosion control structures in place be-
fore cleanup where wind or water erosion is predictable; however, as the
area compacted increases in size, effects on underlying groundwater tables
and adjoining water sheds become more severe.  Community flood control
structures needed for 1.0- and 10-km  fields would exist in deciduous agri-
cultural zones.
     Desert crop system impact indices are shown in Table 8-6.  Removing
soil and chemically or mechanically stabilizing the fields has relatively
low impact because the coarsely textured soils pack together poorly and
plant nutrients are dispersed vertically throughout the profile.  Surface
soil removal has less impact on fertility than in other land types, and a
lower impact recovery time index rating.  Soil renovation practices needed
for recovery are ordinary irrigation management practices in irrigated
agriculture.  Soil chisels and heavy fertilization are common.
     Grasslands in small grains and irrigated row crops have deep lying
nitrogen reserves in the soil profile and are less impacted than the shal-
lower profile on the forested land types.  The relative impact index for
grasslands under cleanup is given in Table 8-7.  Soil cover in grasslands
may add weed seeds and be infertile, which has more impact than in forested
lands which are of lower fertility initially.
     Removing the upper profile has severe impact on later crops in the
deciduous forest land type by removing fertility in organic matter and nu-
trients.  The deeper cuts have greater impact as shown in Table 8-8.  Runoff

                                   8-33

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erosion is more of a problem because the deep cuts on pastures remove pro-
gressively more grass roots, that have bound soil together.  Row crops gen-
erally are on flatter slopes in well managed farms where erosion is less
severe than on scalped pastures.

8.7  CONCLUSIONS
     The preferred cleanup treatments are those which isolate the food chain
from man.  For small areas this may include fencing (treatment 3-1) or apply-
ing hard surfaces (treatments 4-1 and 4-2) to a small area with the expecta-
tion that they will be retrieved at a later date.  Shallow or deep plowing
to 40 cm is acceptable with the exception of eastern orchards which might
suffer moderate root pruning from deep plowing.  Seven of the chemical sta-
bilizers recommended for agricultural use would be appropriate in short-term
response to a contaminating event.
     Cleanup techniques which axe inappropriate in an agricultural area ex-
pected to be returned to crop production are those which involve dispersing
soil by the addition of sodium compounds in large quantities, particularly in
either desert or semi-arid grassland areas.  Removal of the shallow root zone
soil to 40 cm depth should not be considered for areas larger;than 1 or 2 hec-
tares because the problem of disposing of the contaminated soil is a greater
problem than other ways of decontaminating.  Although fenced areas to exclude
cattle have been recommended in the natural ecosystems as a preferred treat-
ment, they are not recommended here because of their position near the top
of the food chain leading to man.  Jt is almost inevitable that domestic
cattle would breach fencing in grassland or deciduous forest areas if the
land is left fenced for more than a few months.
                                   8-37

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8.8  AGRICULTURAL REFERENCES

 1.  Agricultural Research Service.  Predicting Rainfall-Erosion Losses from
     Cropland East of the Rocky Mountains:  Guide for Selection of Practices
     for Soil and Water Conservation.  Agriculture Handbook No. 282, U.S.
     Dept. of Agriculture, 45 pp.

 2.  Agricultural Research Service.  A Universal Equation for Measuring Wind
     Erosion—An Aid to Conservation Farming in the Great Plains.  U.S. Dept.
     of Agriculture, Special Report ARS-22-69, 1961, 20 pp.

 3.  Agricultural Research Service.  Wind Erosion Forces in the United States
     and Their Use in Predicting Soil Loss.  Agriculture Handbook No. 346,
     U.S. Department of Agriculture, 42 pp.

 4.  Alberts, E.E., G.E. Schuman, and R.E. Burwell.  Seasonal Runoff Losses
     of Nitrogen and Phosphorus from Missouri Valley Loess Watersheds.
     J. Environ. Qual., Vol. 7, No. 2, 1978, pp. 203-208.

 5.           .  Don't drift . . . avoid Wind Erosion.  Agribook Magazine,
     Vol. 3, No. 1, 1977, p. 10.

 6.  Bar-Kochba, Y., and A.L. Simon.  Factors Affecting Floods from Watersheds
     in Humid Regions of Northeastern Ohio.  Water Resources Bulletin, Vol. 8,
     No. 6, 1972, pp. 1235-1245.

 7.  Barrows, H.L., and V.J. Kilmer.  Plant Nutrient Losses from Soils by Water
     Erosion.  Advances in Agronomy, 15:  303-316, 1963.

 8.  Bennett, F.W., and R.L. Donahue.  Processes, Procedures and Methods to
     Control Pollution Resulting from Silvicultural Activities.  Misc. Publi-
     cation, U.W. Environmental Protection Agency, Office of Air and Water
     Programs, Washington, D.C. 1973.

 9.  Chepil, W.S., and N.P. Woodruff.  The Physics of Wind Erosion  and Its
     Control.  Advances in Agronomy, 15:  211-302, 1963.

 10.  Godfrey, R.S., ed.   Building  Construction Cost Data, 34th Annual  Edition.
     Robert Snow Means Co., Inc.,  Duxbury, Mass., 1975,  330 pp.

 11.  Hotes, F., L.K.H. Ateshian, and B.  Sheikh.  Comparative Costs  of  Erosion
     and  Sediment Control, Construction  Activities.  EPA-430/9-73-016, U.S.
     Environmental Protection Agency, Washington, D.C.,  1973,  205 pp.

 12.  Jenny, H.  Factors of Soil Formation.  McGraw-Hill,  New York, 1941.

 13.  Nuttonson, M.Y.  Wheat-Climate  Relationships and  the  Use  of Phenology in
     Ascertaining the Thermal  and  Photo-Thermal  Requirements of  Wheat.   Ameri-
     can  Institute of Crop  Ecology,  Washington,  D.C.,  1955,  388  pp.

 14.  Ryden, J.C., J.K.  Syers,  and  R.F. Harris.   Phosphorous  in Runoff and
     Streams.   Advances  in  Agronomy,  25: 1-45,  1973.

                                      8-38

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15.



16.



17.



18.
      D        ™
     , Fart  it  1924.
                    >  Z°n>  Natural  Vegetation.  Atlas of American Agricul-
'H'  WiSCh*eier-
                                            Erosion.  Advances  in Agronomy,
Wischmeier  W.H.  A Rainfall Erosion Index for a Universal Soil-Loss Equa
tion.  Soil Sci. Soc. Amer. Proc. 23: 246-249, 1959.

Wischmeier, W.H.  Use and Misuse of the Universal Soil Loss Equation
Soil Erosion, Prediction and Control.  Soil Conservation Society of
America, Ankeny, Iowa, 1977, pp. 371-378.
                                     8-39

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                                 CHAPTER 9
                           URBAN/SUBURBAN AREAS
9.1  OVERVIEW
     Urban/suburban areas differ from the agricultural and undeveloped areas
addressed in other chapters of this report in a number of ways that affect the
reclamation decisions and their impacts.

     The characteristics of urban/suburban areas that may influence the cleanup
strategies and procedures are diverse.  At one extreme, urban/suburban areas
include downtown areas of major cities which are completely covered by build-
ings and pavements, with residential and transient populations numbering hun-
dreds of thousands of people per square mile at any one time.  In contrast,
urban/suburban areas also include single-family homes on spacious lots with
only a small fraction of the land area covered by buildings and paved walkways
and roadways, and with populations of, at most, a few thousand persons per
square mile.  Between these extremes are various other types of land use
classes, such as commercial and industrial sections.  In addition, within an
area of certain overall characteristics, such as a residential area of single-
family homes, great diversity can exist.  Such places can have significant park
and recreational areas, scattered shopping centers and other commercial areas,
and undeveloped areas.*

     In addition to the diversity of population density and land use and the
degree of structural buildup, a particular area will have other characteristics
that influence the cleanup options.  Some of these factors are:  the surface
and subsurface hydrology of the area, the existing sewer and storm-drain sys-
tem, availability of equipment and manpower, the source of water supply (in-
cluding areas outside the affected area whose water supply might become
*Undeveloped areas within urban/suburban areas are not addressed in this chap-
 ter.  For these areas, the land type which best describes the undeveloped
 area should be determined and the appropriate chapter in this report referred
-to while recognizing that the greater likelihood of human exposure in the
 vicinity of urban/suburban areas may require special considerations as to the
 cleanup techniques.
                                      9-1

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contaminated unless care is taken), season of the year (e.g.,  whether the
ground is frozen or covered with snow), and short-term meteorology (e.g.,
humidity, winds, likelihood of rain).

     From this discussion it must be recognized that for any particular inci-
dent that releases contaminating materials in an urban/suburban area, the
courses of action and the effectiveness and consequences of such actions are
highly dependent on the specific situation.  However, it is useful to attempt
to describe a "typical" urban/suburban area.  One important characteristic is
the fraction of land area that is covered by (1) impervious surfaces such as
roofs, paved walkways and road areas,  and  (2) permeable surfaces consisting
of lawns, plants and trees, and bare earth.  Each of these types of areas
requires different cleanup techniques having different environmental impacts.

     The Census Bureau defines an "urbanized area" as a central city (or con-
tiguous cities) with a total population in excess of 50,000 plus the surround-
ing "closely held" populated areas, i.e., what is generally thought of as an
urban area and its suburbs (exclusive of large parks, golf courses, cemeteries,
etc.).  Based on 1970 Census data,  there were 248 such urbanized areas in the
United States with a total land area of 35,081 square miles and a total  popu-
lation of 118,446,566 people, or 58 percent of the total U.S. population.
Thus, according to the U.S. Bureau  of the  Census , the average population
density in urbanized areas is 3,376 people per square mile.

     National statistics regarding  the fraction of ground surface covered by
streets, buildings and permeable surfaces  in urban/suburban areas could  not
be found, so residential areas in  Santa Barbara, California,  were randomly
selected and surveyed to develop these statistics.  The population density of
the "place" of Santa Barbara  is 3,333 people per square mile6, which is  in
excellent agreement with the  average population density of urbanized areas,
so it is assumed that statistics for Santa Barbara are reasonably representa-
tive of  typical urban/suburban areas of the Nation.

     Within single-family  housing  tracts  of Santa Barbara, the approximate
coverage of the ground  surface area is 20  percent by buildings;  15 percent
by streets; 8 percent by driveways, sidewalks,  walkways, patios,  etc.;  and
the remaining  57 percent by  lawn and soil  areas.  Thus  within housing  tracts,
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the  impervious surfaces comprise approximately 43 percent of the surface
area.  Such single-family housing tracts that are fully developed have popu-
lation densities of approximately 10,000 persons per square mile.

     The above statistics are applicable for small areas within fully devel-
oped single-family housing tracts.  Within a larger area, the permanent popu-
lation density is less because of commercial areas, open spaces, etc., and
therefore -the proportion of the area which is covered by impervious surfaces
may differ.  A recent study was concerned with the recharge of groundwaters
in suburban areas of Santa Barbara.   Within the area of interest of that
study, which can be described as primarily residential single-family suburban
housing tract areas (upper-middle to middle income housing), the population
density is approximately 3,500 to 4,500 persons per square mile (i.e., roughly
in agreement with the typical population density of an urbanized area).  The
ground surface consists of approximately 37 percent impervious surfaces (build-
ings, streets, etc.), 24 percent lawn and yard areas, 9 percent agricultural
areas, and 30 percent open space and native vegetation areas.  Thus it can be
seen that a surprisingly large percentage of a suburban area (39 percent for
the case of Santa Barbara) consists of areas having "rural" or "natural" char-
acteristics.  However; the percent of surface which is impervious is not much
less than the value of 43 percent within housing tracts.

     It is estimated that approximately one-half of the rainfall from small
storms in Santa Barbara that falls on impervious surfaces finds its way to
storm sewer systems with the remaining one-half soaking into the ground.4
Therefore,  if the cleanup option is to flush the contaminant from building
roofs,  streets,  and walkways with water, approximately one-half of the con-
taminated water can be expected to soak into the ground unless measures are
taken to prevent this occurrence.

     Other data for the upper Santa Ana Valley in California indicate that the
fraction of land area which is covered by impervious surfaces varies linearly
from approximately 20 percent for an area that is 40 percent urban developed
to approximately 70 percent for an area that is 100 percent urban developed.4
For the Santa Barbara area,  which is approximately 60 percent urban developed,
the ground surface should be approximately 38 percent covered by impervious
surfaces.   This  is in excellent agreement with the actual value of 37 percent.
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     In summary, the characteristics of small areas of 0.01 km  in size withir,
an urbanized area may vary considerably.  If one randomly selects a small area
within an urbanized areas, the probability is approximately 40 percent that
the area will have "rural" or "natural" characteristics rather than urban
characteristics.  As the area, of contamination is increased to the maximum of
10 km2 used in this study, the characteristics of the area approach the aver-
age characteristics of 60 percent urban developed with 37 percent of the land
covered by impervious surfaces and a population density of approximately 3,400
people per square mile.

9.2  NATURAL PERTURBATIONS
     Natural perturbations that produce some of the environmental effects that
could occur from cleanup treatments in urban/suburban areas include most of
the natural disasters, i.e., floods, fires, earthquakes, and severe storms.
In most cases, these natural perturbations will have significant effects on
man-made structures; whereas the reclamation treatments will have little ad-
verse effects.  In contrast, some of the reclamation techniques will typically
have more adverse effects on the "natural" ecology of urban/suburban areas than
do natural disasters.  For example, removing 40 cm of soil will destroy essen-
tially all vegetation, whereas no natural disaster is likely to produce this
degree of total destruction.

9.3  MAN-MADE PERTURBATIONS
     A number of activities of man can cause destruction to the man-made envi-
ronment and the natural environment of urban/suburban areas.  Such activities
include war, urban development or redevelopment, and spills of hazardous ma-
terials.

     The normal construction activities associated with urban development or
redevelopment usually employ most of the cleanup techniques that are discussed
in Section 9.4.  Typically, earthmoving and destruction of vegetation are re-
quired to prepare land for development.  By design, the land is not allowed
to return to its natural condition; instead, lawns are established and desir-
able trees and  smaller plants are planted.  Within a few months to a couple
of years the desired vegetation, except large trees, is established.
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      Spills  of materials  that  are  hazardous  or  ecologically damaging  require
 cleanup techniques  identical or  similar to the  treatments  for  cleanup of  radio-
 active material.  Again,  in the  urban/suburban  situation there is usually no
 significant  lasting effect  (except for  social and  economic impacts) because
 the  artificial man-made environment that is  disturbed by the treatment can
 usually be reestablished  relatively quickly.  An exception to  this  statement
 would OCCIT  if the  contamination could  not be cleaned up to the necessary de-
 gree,  forcing  restriction or abandonment of  an  urban/suburban  area  or removal
 of structures.  However,  even  in this case the  impact is primarily  social and
 economic, with little additional effect on the  natural  environment.

 9.4   EFFECTS OF CLEANUP PROCEDURES  ON
      URBAN/SUBURBAN AREAS
      The urban/suburban environment  is  largely  a man-made  environment,  in
 contrast to the natural environments of undeveloped areas.   Some cleanup  op-
 tions  that might^cause significant  environmental impact in  undeveloped  areas
 (e.g., vegetation clearing, removal of  soil  layers, and applying soil  cover)
 are common activities in  urban/suburban areas.

      Because of the greater hazard to humans from contamination of urban/
 suburban areas, a greater cleanup effort  is not only justified but required.
 To clean up the area to the maximum possible extent, a series of cleanup  tech-
 niques would probably be used rather than a single technique.  The effective-
 ness of the cleanup is primarily limited only by the monetary cost of carrying
 out the tasks.  For example, contaminated roofs could be stripped of shingles
 and reshingled if necessary.  Contaminated pavements could  even be removed.
 In an urban/suburban area, virtually the entire surface area could be stripped
 and removed without significant  impact on the "natural" ecology—but with a
high monetary and social cost.

     Treatments that can be used in urban/suburban areas to remove contami-
nants or to reduce the hazard from such contaminants can be grouped into
those that lend themselves to application for lawn, plant,  and soil areas in
yards and parks (treatments 1-1 through 7-0 in the following list),  and those
 that lend themselves to application for hard, relatively impervious, artifi-
cial surfaces, such as building roofs, walkways, and paved areas (treatments
8-1 through 8-7 in the following list).
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         Treatments for Lawn, Plant and Soil Areas*

         0-1  Natural Rehabilitation-
         1-1
         1-2
         1-3
         1-4
         1-5
         1-6
         1-7
         1-8

         2-1
         2-2
         2-3
         2-4
         2-5
         2-6
         2-7
         2-8

         3-1
         3-2
         3-3

         4-1
         4-2

         5-0

         6-1
         6-2

         7-0
Chemical Stabilization
Clear Cutting Vegetation
Stumping and Grubbing
Scraping and Grading
Shallow Plowing
Deep Plowing
Soil Cover Less than 25 cm
Soil Cover 25 to 100 cm
       Plow Layer
       Shallow Tloot Zone
       Scraping and Grading, Mechanically Stabilize
       Plow Layer, Mechanically Stabilize
       Shallow Root Zone, Mechanically Stabilize
       Scraping and Grading, Chemically Stabilize
       Plow Layer, Chemically Stabilize
       Shallow Root Zone, Chemically Stabilize
Remove
Remove
Remove
Remove
Remove
Remove
Remove
Remove
Barriers to Exclude People
Exclude Large Animals
Exclude Large and Small Animals
Asphalt Hard Surface Stabilization
Concrete Hard Surface Stabilization
Application of Sewage Sludge
High Pressure Washing (<3 mm)
Flooding to 30 cm
Soil Amendments Added
          Treatments for Hard,  Impervious,  Artificial  Surfaces
          8-1  Washing with High-Pressure Water (Firehosing)
          8-2  Vacuuming
          8-3  Sweeping
          8-4  Mechanized Street Flushing
          8-5  Surface Removal  Techniques
          8-6  Other Removal Methods
          8-7  Containment

    ' In general, treatments 1-1 through 1-8 are not treatments for the removal

of a contaminant (although 1-2 is a removal treatment if contamination of
vegetation is significant).  Instead, these treatments are those that might be
*This list of treatments applies to all land types, and is included for a com-
 plete discussion.  Some of these treatments are not appropriate for urban/
 suburban areas.
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 applied  as  a  temporary measure  to  hold  the  contaminant  in  place  to  prevent  its
 redistribution.   In  the  case  of treatments  1-5  through  1-8,  the  immediate haz-
 ard  is reduced because the  contaminant  is shielded  by soil cover.

     Treatments  1-1  through 7-0 apply to land types in  general.  • Most  of these
 treatments  also  apply for the lawn, plant,  and  soil areas  (yards) of urban/sub-
 urban areas.  However, in the urban/suburban situation  some  of the  treatments
 may  be more appropriate  than  others and the environmental  impacts may  be sig-
 nificantly  different than would be the  case for an  undeveloped or, agricultural
 area.

     Because of  the greater potential hazard from a contaminating incident  in
 a populated area, several of  the treatments might be used  on urban/suburban
 yards so as to reduce the hazard to the maximum practical  extent.   For example,
 a stabilizer might be applied to lawns  to hold  the  contaminant in place while
 the  sod is  removed and any  residual contamination hazard might be further re-
 duced by turning over the soil  before resodding.

     Depending on circumstances it may  be desirable or  it  may be -undesirable
 to coat the ground with a sealant, such as  liquid asphalt, so that  contami-
nated water from washing of roofs and walkways  will run off into the storm
drain system rather than soak into the  soil.

     Flushing with water or blowing with compressed air may remove the con-
taminant from the foliage of plants if  the resuspension in air or the washing
into the soil of the contaminant is acceptable.   Otherwise, the contaminant
can be fixed onto the leaves of the plant by a  stabilizer  and then the plant
can be pruned, defoliated, or removed.

     Some of the treatments which are used for  cleanup of hard artificial
surfaces, such as sweeping and firehosing,  cam  also be used with some limited
effectivess on frozen ground.

     Each of the potential treatments is discussed below in the order listed.
The discussion is based primarily on Owen et al.  and to a lesser extent on
Bennett and Owen  and Cobb and Van Hemert.
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9.4.1   Lawn,  Plant and Soil  Area Treatments
     (0-1)   Natural Rehabilitation
     Because of the proximity of humans, it is assumed that doing nothing to
clean up urban/suburban areas is not a viable option; rather, any contamina-
tion will have to be reduced to some acceptably low level.   Therefore, natural
restoration does not apply for urban/suburban areas.

     (1-1)  Chemical Stabilization
     The purpose of the chemical stabilizers is to hold the contaminant in
place, to prevent redistribution until the contaminant can be removed.  The
properties of the general classes of chemical stabilizers are given in Appen-
dix A, Soil Stabilizers.  Chemical stabilizers vary as to their effectiveness
and longevity in holding the contaminant in place and in their effects on
vegetation.  Some of the stabilizers cannot be used without necessitating
subsequent removal of the vegetation>

     In  lawn areas the sod will undoubtedly be removed and the lawn area re-
established with seed or resodding,  in which case the use of chemical stabi-
lizers has no significant adverse environmental effect.

      (1-2)   Clear Cutting Vegetation
     For lawns  and ground covers, this  treatment consists of mowing or perhaps
renovating down to the soil.  There  is  no  significant adverse effect  from mow-
ing or renovating, since the root zone  is  not damaged and the grass or ground
cover grows back relatively  quickly.

      In  general,  clear cutting  of bushes and  trees  is to clear the ground  sur-
face  for plowing or  soil removal.   Many bushes,  and some  trees,  will  reestablish
from  the r-oot  systems of  the clear-cut  vegetation,  although  not  as quickly as
grass.   The  time to  reestablish varies  from  a year  for  small  shrubs to many
decades  for  large trees.

      (1-3)   Stumping and Grubbing
      This  treatment  contributes little  additional  impact  to  that which occurs
when the trees and bushes  are  cut down.  If  trees  are cut  down,  new  trees  would
probably be planted so  removal of stumps is  desirable.   Shrubs would  have  to be
replanted rather than allowed to propagate from existing root systems.

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      (1-4)   Scraping and Grading
      The removal  of up to 5  cm of soil  by scraping  and  grading  is  equivalent
 to removing the sod layer for lawns.  Removal  of this layer  will not have any
 effect  on trees and larger shrubs unless  they  must  be removed to provide room
 for equipment.  Smaller plants may be damaged,  but  they would likely be re-
 moved in any case to ease the task of scraping and  grading.

      (1-5)   Shallow Plowing
      The disturbance of the  upper 10 cm of soil by  shallow plowing will have
 more significant  effects than treatment 1-4.   If plowing is  done close to
 small plants they may be killed by root disturbance; but most trees will not
 be killed or seriously damaged by plowing to this depth.

      (1-6)   Deep  Plowing
      Deep plowing (10  to 40  cm)  will have more  serious  effects on  trees.  Most
 trees in  yards and parks have shallow root systems  because of improper water-
 ing;  plowing  to a depth  of 40 cm will damage these  root  systems.   However, be-
 cause of  interference by larger  roots it  may not  be possible to plow close to
 the  tree, so many trees  that  might otherwise be killed by close plowing will
 survive.

      (1-7)  Soil  Cover less than  25 am

      (1-8)  Soil  Cover 25 cm  to  100 am
      If not only  a temporary  treatment, and if not  removed within  a relatively
 short time period, soil  cover  in  an urban/suburban  area will change grade lev-
 els  and affect water drainage around buildings.  As a short-term measure,  add-
 ing  soil cover will not  affect trees and  larger bushes.   Smaller bushes may be
 covered and killed and lawns will die in  a short time period.

      Except for palms, trees cannot tolerate the permanent addition of soil
unless measures are taken to ensure adequate air circulation about the trunk
down  to the original grade level.  If soil is placed around the trunk,  rot
will  set in and the tree will eventually die.  The  addition of 25 cm of soil
will have no effect on trees if it is kept from the trunk.  A 100-cm layer
requires a larger space around the trunk to ensure  adequate air circulation,
and can be expected to affect the root system of the trees by oxygen depletion.
                                     9-9

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     There may be practical limitations on using soil cover.   To cover the
ground to a depth of 100 cm in one square kilometer of the typical urban
area, whose surface is comprised of 63 percent soil and vegetation, requires
824,000 cubic yards (630,000 cubic meters) of fill soil.

     Treatments 2-1 through 2-8 are designed to remove a contaminant from
yards so that it can be transported to a safe place.  These treatments are
straightforward—by whatever means are practical, sod and layers of soil are
removed until the residual contamination is at an "acceptable" level.  In the
urban/suburban situation, uncontaminated topsoil will usually have to be
brought in as fill to restore yards to the original grade level.  Stabilizers
might be used to prevent erosion, but stabilization techniques which have
adverse effects on the revegetation of the area, such as compacting, would
not be required.  Stabilization is required only for a relatively short time
period while lawns become established.

     The depth to which soil can be removed from around a tree without injur-
ing or killing the tree depends on the proximity of the root system to the
ground surface.  This, in turn, primarily depends on the type of tree, its
location, and the watering it has received.  Some of the most desirable trees,
such as maples and some oaks and conifers, have relatively shallow root sys-
tems.  Also, because of frequent and shallow watering, trees in yards often
develop root systems relatively close to the ground surface; such trees ar&
more susceptible to damage from soil removal than are trees which rely on
rainfall.

     For lawns, using sod cutters and rolling up the sod for hauling away is
effective.  Past experiments indicate that this procedure will remove 98 per-
cent to 99 percent of a contaminant.  Removing sod by garden tractors or by
hand shoveling appears to be less effective in removing contaminant than us-
ing a sod cutter, although the data are limited.

     Where access is not restricted, larger machinery such as bulldozers, back-
hoes, road graders, etc., may be used to scrape off the top layers of soil.
Typically, for large working areas, removal of 5 to 10 cm of soil will  sig-
nificantly reduce contamination, although results are quite variable.  For
smaller working areas, such as typical urban/suburban yards, the effectiveness
of heavy machinery is limited and it must be supplemented by hand  labor.
                                     9-10

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      The magnitude  of  the  disposal  problem  associated  with  removing  contami-
nated soil,  and  the task of  hauling in uncontaminated  soil  for  fill, must be
appreciated.   Removing the plow  layer of  soil  (10  cm)  from  the  "typical"
urban/suburban area requires  the disposal of 82,400  cubic yards (63,000 cubic
meters) of contaminated earth per square  kilometer,  compacted to  the original
density.  Disturbed earth  takes  up  more volume than  undisturbed earth, prob-
ably  by a factor of 20 to  40  percent, so  removing  the  plow  layer  of  soil from
a 10-km2 typical urban/suburban  area requires disposing of  approximately one
million cubic  yards of contaminated earth and hauling  in the same volume of
uncontaminated earth for fill.   Removing  soil in the shallow root zone quad-
ruples these requirements.

      (2-1)  Remove  Plow Layer
      In the urban/suburban situation there  is little impact from  removing the
top 1.0 cm of soil from  yards.  Lawns can be reseeded or resodded, and plants
and small bushes can be replaced.   Only very shallow-rooted trees will be
seriously damaged or killed by the  removal of soil to  this depth.

      (2-2)  Remove Shallow Root  Zone
     Whether or not a tree is killed from removal of 40 cm of soil depends
on the particular tree and its situation; however, in  general,  the removal
of this amount of soil will probably kill most trees that do not have signif-
icant taproots.  The use of heavy equipment will cause more damage than care-
ful use of hand tools.
     , . : » " ' , , ".  •
      (2-3)  Remove Seraping and  Grading,  Mechanically Stabilize
     Removal of the top 5 cm of  soil will have no significant effect on trees
and large bushes.  This is equivalent to removing the  sod layer from lawns.
The lawns can be reseeded or resodded,  and smaller plants that have been
removed can be replaced.  Compacting of the soil for erosion control would
not be required;  other means of  stabilization that are practical would have
no significant adverse effects.
     (2-4)  Remove Plow Layer, Mechanically Stabilize
     The impact is the same as for treatment 2-1, provided compacting or hard-
surface stabilization techniques are not used.

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     (2-5)  Remove Shallow Root Zone, Mechanically. Stabilise
     The impact is the same as for treatment 2-2, provided compacting or
hard-surface stabilization techniques are not used.

     (2-6)  Remove Scraping and Grading, Chemically Stabilize
     The impact is the same as for treatment 2-3.

     (2-7)  Remove Plow LayeT3 Chemically Stabilize
     The impact is' the same as for treatment 2-1.

     (2-8)  Remove Shallow Root Zone, Chemically Stabilize
     The impact is the same as for treatment 2-2.

     (3-1)  Barriers to Exclude People
     This technique is probably practical only as a short-term measure while
the contaminant is removed.  Barricading people from urban/suburban areas to
which they normally have access for  longer than a few days or weeks would
cause considerable social disruption and adverse economic impact.

     (3-2)  Exclude Large Animals
     Any barrier to exclude large animals would also exclude people, which is
unacceptable in an urban/suburban area  except for a brief time period.  Because
of the relative scarcity of large animals in urban/suburban areas, there would
be no significant impact on them.

     (3-3)  Exclude Large and Small Animals
     Except for very small areas, exclusion of small animals would be difficult.
Household pets would have to be relocated with their owners or impounded.  Wild
animals, primarily birds and rodents, might multiply.  They also might become
vectors for spreading a contaminant  to  other areas.

     (4-1)  Asphalt Hard-Swfaoe Stabilization
     Probably in most cases asphalt  hard-surface stabilization would be com-
bined with some degree of plant and  soil removal,  thus entailing additional
logistic and economic problems both  for initial  treatment and subsequent
                                      9-12

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removal.  An asphalt surface would kill any unremoved vegetation.  Unre-
moved  trees would die  from  lack of water  and  oxygen  to  the roots.

     Ii^JLLJ?grcorete Hard-Surfaae Stabilization^
     The same comments apply as for  treatment 4-1, except that concrete would
provide a more permanent surface or,  if removed, be  slightly more difficult
to break up and transport.

     (5-0)  Appliaation of Sewage Sludge
     Outside the scope of work.

     (6-1)  High-Pressure Washing
     Outside the scope of work.

     (6-2)  Flooding to 30 am
     Outside the scope of work.

     (7-0)  Soil Amendments Added
     Outside the scope of work.

9.4.2  Impervious, Artificial Surface Treatments
     The treatments that may apply to remove a contaminant from the hard, im-
pervious artificial surfaces that cover much of the urban/suburban land areas
are:   washing with high-pressure water (treatment 8-1), vacuuming (treatment
8-2)," sweeping (treatment 8-3), mechanized street flushing (treatment 8-4),
surface removal techniques (treatment 8-5), and other removal techniques
(treatment 8-6).

     As would be expected,  smoother surfaces retain less residual contaminant
than  rougher surfaces,  larger particulates are more effectively removed than
smaller particulates,  and the fraction of contaminant removed is greater for
initially greater loading densities.   Data on the effectiveness of the cleanup
techniques are primarily based on results of simulations using sand.   The par-
ticulate sizes were often on the order of 100 microns or more and the surface
loading densities on the order of 100 grams/ft2.  For smaller particulates and
less  dense surface loading,  effectiveness should be considerably less.

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     (8-1)  Washing with High-Pressure Water f>3 mm)
     Large, impervious areas such as roofs and streets can be cleaned by high-
pressure streams of water.  The high-pressure water dislodges and dilutes most
of the contaminating particles and carries them away in the runoff.   In this
case, the contaminant is simply being moved to a different location.  Deter-
gents, manual or motorized scrubbing, and special hose nozzles may be employed.
In general, firehosing has been envisioned as an emergency technique to be used
in catastrophic situations to clean up a relatively large populated area where
concern with the runoff of contaminated water is secondary to reduction of the
immediate hazard.

     Examination of results from numerous experiments summarized by Owen et al.
indicates that, in general, firehosing will remove 90 percent or more of con-
taminating particulates from areas paved with asphalt, concrete, and asphaltic
concrete.  Often less than 1 percent of the residue remained after a single
pass.  Repeated passes with the water stream removed more contaminant, but
with decreasing effectiveness.  Contaminants in  slurrys appear to be removed
as effectively as are particulates.  Although roofs are not as effectively
firehosed as are street areas, tar-and-gravel and composition shingle roofs
can be 90 percent or more decontaminated.  Limited data on wood  shingles  indi-
cate 80 to 90 percent decontamination effectiveness.

     Firehosing roofs and paved areas requires  10 to  20 liters of water per
square meter of area per pass.  To  treat a typical suburban area in .this  man-
ner would  require 1 to  2 million gallons  (3.7 to 7.4  million  liters) of water
per square kilometer per pass, exclusive of water needed  to wash down vertical
      *l                                            O
surfaces.  Even the smallest-sized  area of 0.01  km  would result in  500 to
1,000 50-gallon drums of wastewater.  Thus,  except for very  small areas,  it may
not be practical to collect  and  store contaminated wastewater from  cleanup  .

     Hosing down impermeable  surfaces simply moves the bulk of the  contaminant.
to a different location and/or reduces it to more acceptable  concentrations.
Runoff from structures  moves  the contaminant  to the ground level onto other
impermeable surfaces, or  onto soil  and plants.   Flushing  walkways and  streets
moves the  contaminant onto  soil  surfaces  or  into storm drain systems.   If
                                      9-14

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 measures are not taken to collect the runoff, shrubs, lawns, and bare earth
 areas will receive contaminated water as will storm drain discharge points.

      Uncontaminated, permeable surfaces can be sealed with substances such as
 liquid asphalt to prevent contaminated runoff water from soaking"into the
 ground.  However, it is unlikely that all splashes can be contained; in fact,
 it may be desirable in some instances to let contaminated runoff water soak
 into permeable ground surfaces as a means of contaminant collection.  Radio-
 active contaminants are often quite insoluble and can be effectively filtered by
 soils, and the portions that are soluble are quickly adsorbed onto surface
 soil particles.   For example,  as discussed in The Behavior of Radioactive
 Fallout in Soils and Plants^  approximately 99 percent of fallout is insoluble
 (in distilled water)  and a solution oi soluble portions poured through the
 soil in one set  of experiments was 80 to 85 percent adsorbed by the first few
 centimeters of soil.   Plutonium,  a radionuclide of great concern,  is very in-
 soluble in water and  might best be trapped by soil filtration and subsequent
 removal of a layer of soil.

      (8-2)   Vaouuming
      Removal  of  contaminating  particulates from hard  surfaces by  vacuuming  has
 not  been  examined  in  as much detail  as other  techniques,  such as  firehosing.
 The  reason  for this relative neglect may be because of  the  slow working rate
 compared  to  firehosing.  A street  can be firehosed at a  rate  of 300  to 500
 square  feet per minute compared to a few tens of square  feet  per minute for
 vacuuming.  Nevertheless,  examination of the data from Owen et al.5  indicates
 that vacuuming can be effective in removing particulate  contamination from
 hard surfaces.  In general, based on  a limited number of experiments, vacuum-
 ing can remove in excess of 90 percent,  and sometimes in excess of 99 percent,
 of the particulate contamination from composition shingles and concrete with
 a single "pass."  In the single experiment where repeated vacuumings were
 employed to decontaminate concrete, the  second vacuuming removed 90 percent
 of the residue from the first vacuuming and the third and fourth vacuumings
 removed about one-half of the remaining residue.  Thus, it appears that care-
 ful vacuuming can remove in excess of 99 percent of particulate contamination
from pavement and roofs.  In an experiment for decontaminating frozen bare
ground, vacuuming removed about 60 percent of the contaminant after 4 passes
 (40 percent was removed on the first pass).
                                     9-15

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     Details on the design of the vacuuming experiments are not.available,
but it is presumed that the particulates were "fresh," i.e., the particulates
were not allowed sufficient time to "weather" and become more firmly attached
to the contaminated surfaces.

     Vacuuming has a significant advantage over firehosing and other types of
methods that simply move the contaminant to another location because vacuum-
ing picks up the contaminant and contains it for safe disposal.  Care must be
taken that absolute filters are used, in addition to the coarse filters in
the typical vacuum cleaner, so that very small particulates will be trapped
rather than resuspended in the air by the cleaner's exhaust.  Otherwise, no
adverse environmental effects appear to be associated with vacuuming contam-
inants from hard surfaces.

      (8-3)  Sweeping
     Mechanized street sweepers can remove significant amounts of contaminants
from dry paved surfaces.  In experiments few passes of these sweepers typically
removed more than 99 percent of the contaminant.  Mechanical street sweepers
have a realtively high rate of cleaning, e.g., a few thousand  square feet per
minute per pass.  Again, in a large-scale emergency where  the  primary concern
is to reduce the gross hazard as quickly as possible,  street sweeping may be a
viable technique.  However, in cases where it  is less  critical,  street  sweepers
probably would be a less acceptable alternative due to resuspension of  paticu-
late  materials.  Dust can be kept down  to  some extent  by  sprinkling.  In any
event, mechanized street sweepers can only be  used on  large paved  areas where
access is available.  (Street sweepers can  also be used, with  limited effective-
ness, on open  areas of  frozen ground.)  Hand brooms have  some  limited effective-
ness  for sweeping roofs.

      Environmental  impact  from  sweeping is  limited  to particulate  resuspension.

      (8-4)   Mechanized Street Flushing
      As  is  the case with mechanized street sweepers,  street flushers have  the
 advantage  of a high rate of areal coverage,  e.g.,  a few thousand square feet
 per minute per pass.   A single  pass typically removes 90 to 99 .percent  of the
 contaminant and a second pass  typically results in more than 99 percent removal
 of the original amount of contaminant.   Thus mechanized street flushers appear
                                      9-16

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 to be as  effective as  firehosing  and  faster.   However,  their use  is  limited
 to streets  or other large paved areas.

      Using  mechanized  street  flushers-poses  the  potential  problem of flushing
 contaminants  into the  storm sewer system and thence  into the sewage  treatment
 plant or  some other discharge point.   If this is not desired,  the runoff must
 be captured.   Otherwise,  there are no significant adverse  ecological effects.

      (8-5)  Surface Removal Teohni-ques
      Firehosing,  flushing with water,  sweeping,  and  vacuuming  do  not usually
 have  any  significant effect on the building  or paving surfaces which are being
 decontaminated.   Another  class of cleanup techniques for hard  surfaces consists
 of removal  of some  of  the surface to  which the contamination adheres.  Surface
 removal techniques  would  likely be applied only  for  residual contamination
 which cannot  be removed by the nondestructive techniques.  These  techniques
 include removal of  contaminated surfaces by chemicals,  scraping or wirebrush-
 ing,  sandblasting,  or  other abrasive  techniques.  Sandblasting, while very
 effective in  removing  contaminants from hard  surfaces,  poses the  hazard of
 suspending  contaminants in air unless preventive measures are  taken.

      Using  surface  removal techniques on artificial  surfaces poses no signif-
 icant  ecological problems.  Paint  stripping requires  the use of caustic chem-
 icals, but  the sludge will have to be collected  in any  case.   Sandblasting is
not a viable  technique unless measures are taken to  contain the particulate
dust which would otherwise be  resuspended in  the air.

      (8-6)  Other Removal Methods
     Other methods for removing contaminants from hard  surfaces,  primarily
small areas,  include wiping with tac-cloths or similar material,  applying
strippable films,  and perhaps even ultrasonic cleaning.   Strippable films and
wiping are probably only effective on very smooth surfaces such as furniture
tops or automobiles, but may have some application.  Ultrasonic cleaning poses
the possible hazard of resuspending small particulates.

      (8-7)  Containment
     Containment techniques may be used (1)  to temporarily immobilize contam-
inants onto hard surfaces while cleanup measures are being formulated, (2)  as
                                     9-17

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a long-terra measure to seal off a contaminant from being a hazard,  or (3)  as
a final step to seal off any residual radiation after cleanup measures have
been completed.  Containment techniques using an impervious sealant are 100
percent effective for reducing the hazard from alpha emitters since the ex-
ternal hazard from these radionuclides is negligible.  However, the sealant
must be maintained for as long as the underlying surface might be a hazard,
to avoid a hazard when the sealant weathers or otherwise deteriorates.  Paint,
tar, oils, and liquid asphalts are the commonly known containment materials,
based on 1950s and 1960s technology that was primarily concerned with nuclear
weapon fallout.  Many of the soil stabilizers shown in Table A-l (Appendix A)
could also be used to temporarily contain contaminants.

     If the containment is temporary, solvents or other techniques are needed
to remove the sealant to permit cleanup of the surface.  (The sealant itself
may be employed as a means of removing the contamination by "locking onto"
the contaminant so that it is removed with the sealant.)

     Applying techniques for containing contaminants in place on impervious
surfaces and then perhaps removing the containing material may be costly in
monetary terms and disruptive to human activities, but otherwise there is no
significant effect on the environment.

9.5  RECOVERY AFTER CLEANUP
     Most of the cleanup techniques for urban/suburban areas will not cause
significant long-term ecological damage.  Within a matter of months to a year
or two following the destruction of vegetation, lawns and small plants could
be reestablished.  The only  long-term impact would be the lack of large trees
and shrubs, if they had to be removed.

     Many of the treatments  involving earthmoving, destruction of vegetation,
or soil stabilization are commonly used  in urban/suburban areas when preparing
land for development.

9.6  QUANTITATIVE ASSESSMENT OF CLEANUP  IMPACTS
     Table  9-1 is an  estimate of the relative  impact on  the  ecology of an
urban/suburban area as a result of applying  the cleanup  treatments described

                                      9-18

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in Section 9.4.  The impacts are rated on a scale of 0 (no impact)  to 100
(greatest impact) for the various treatments and the size of the area disturbed.

     In the urban/suburban case impact is assumed to be directly proportional
to the area affected, because there are relatively few wild animals, except
those considered pests, to be displaced and the vegetation will be replaced
rather than permitted to reestablish naturally.  Therefore, the impact on a
10-km2 area is assumed to be 1,000 times greater than the impact on the 0.01-
km2 area.  This is" in contrast to undeveloped land types where impact is not
assumed to be directly proportional to the size of the area.

     Treatments 4-1 and 4-2, stabilization with a hard surface, are judged to
be the most severe with a rating of 100.*  Not only will these treatments re-
sult in killing all vegetation and obviating most social and economic uses,
but the surface remains in place for a significant time period, in contrast
to the other treatments where the area can be restored to near its original
condition within a few years.

     Treatment 1-3, stumping and grubbing, and treatments 2-2, 2-5, and 2-8,
removing the shallow root zone, are rated next in severity with a rating of
75.  These treatments will result in the death of essentially all vegetation.
Treatment 1-2, clear cut vegetation, is rated  less damaging at 70 because some
of the vegetation can propagate from existing  root systems.

     Treatments  1-7 and  1-8, soil cover; treatment  1-6,  deep plowing;  and
treatments 2-1,  2-4, and 2-7, removing the  plow  layer,  are  judged roughly
equivalent with  a rating of 50.  Most trees will  not  be seriously damaged  or
killed by these  treatments,  but  all other vegetation  will  be destroyed.  Treat-
ments  1-4, 2-3,  and  2-6, scraping and grading, and  treatment  1-5, shallow  plow-
ing,  are rated approximately equal  with  a  rating of 25.   Damage is  to a lesser
degree than  with removal of the plow  layer.

      Treatments  3-1, 3-2, and  3-3,  barriers to exclude people  and animals,
are  assigned impact  ratings of  10.  Presumably the  barriers are for a short
time period.   Application of sewage sludge  may pose some problems  in social
unacceptability.
 *A11 ratings are for a 10 square km area.

                                      9-20

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      Treatment 1-1,  chemical  stabilization,  and treatments  8-1  through 8-7,
 treatment for artificial  surfaces,  are judged to have negligible environmental
 impact provided they are  done correctly so that the  contaminant is  either con-
 tained or controlled in a desirable manner.

 9.7   CONCLUSIONS
      Although it may be very  expensive and socially  disruptive  to clean up
 contamination from a large urban/suburban  area,  significant adverse effects
 on the natural ecology are short term.   Many of the  treatments  are  used during
 normal construction  activities that occur  in urban/suburban areas.   Within a
 matter of months to  a year or two following  cleanup,  lawns  and  small plants
 will  be reestablished (except in the case  of hard-surface stabilization).
 The only  change  will  be the lack of large  trees  and  shrubs  if they  have been
 removed.   The  consequences of not effectively cleaning up the contaminant
 (e.g.,  human health)  may  be more significant than concern for the environ-
 mental  impact  of cleanup  treatments.  Thus,  environmental impacts must  be
 secondary to selecting the most effective  treatment  or treatments.   The resid-
 ual contamination must be reduced to some  acceptably low level;  if  this neces-
 sitates the complete  destruction of  all vegetation,  that impact must be ac-
 cepted.   In this context  there are no treatments that are'unacceptable, ex-
 cept natural rehabilitation.   Circumstances  will dictate the most desirable
 treatments for a particular situation.

 9.8  URBAN/SUBURBAN LAND AREAS REFERENCES
 1.   Bennett, C.B., and W.L.  Owen.   Planning Radiological Reclamation of Test
     Facilities at Kwajalein Contaminated by Plutonium, Volume II—Radiologi-
     cal Reclamation  Procedures.   U.S. Naval Radiological Defense Laboratory,
     San Francisco, CA 94135,  Report USNRDL-TR-67-68  (AD 820010), 29 May 1967.
      (Official Use Only)
 2.   Cobb, LTC F.C.,   and LTC  R.L.  Van Hemert.  USAF,  Source Book on Plutonium
     and its Decontamination.   Field Command, Defense Nuclear Agency, Technol-
     ogy and Analysis Directorate,  Kirtland Air Force Base NM 87115, 24 Sep-
     tember 1973.
 3.   National Academy of Sciences,  National Research Council.  The Behavior of
     Radioactive Fallout in Soils and Plants.  Washington,  D.C., Publication
     1092, 1963.
4.   Office of Environmental  Quality (in cooperation with Geotechnical Consul-
     tants, Inc.).   Impact of Urbanization on Recharge Potential of  the Goleta
     Groundwater Basin.   Prepared for the County of Santa Barbara, Santa Barbara,
     California, March 1976 (revised July 1976).

                                     9-21

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Owen, W.L., F.K. Kawahara, and L.L. Wiltshire.  Radiological Recalamation
Performance Summary, Volume 1-Performance Test Data Compilation.  U.S.
Naval Radiological Defense Laboratory, San Francisco, CA 94135, Report
USNRDL-TR-967, OCD Work Unit No. 3114A, 13 October 1965.
U.S. Bureau of the Census.  County and City Data Book-1972 (A Statistical
Abstract Supplement).  U.S. Government Printing Office, Washington, D.C.,
1973.
                                  9-22

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      PART III



      WILDLIFE







CHAPTER 10, WILDLIFE

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                              CHAPTER  10
                              WILDLIFE
 10.1  OVERVIEW

     A  large amount of information must be integrated to describe which
 impacts to wildlife will occur in particular situations.  For example,
 the time span over which impacts occur, the type of disturbance, land
 area, land types, vegetation component,  wildlife component, and wild-
 life ecology all must be considered.  In addition, feedback and inter-
 actions among these factors must be considered.  So that this informa-
 tion can be more easily dealt with, several simplifications will be
 made.  These include a standardization of the above variables.  This is
 followed by a general discussion of characteristics which relate to im-
 pacts on each wildlife group of birds and mammals.  This discussion is
 made first for immediate impacts, and then repeated for long-term effects.

     The term "ecological impact" implies two basic actions.  First,
 there is some disturbance to an area.  Second, there is a reaction
 (impact) which results from the disturbance.   Of interest are those im-
 pacts caused by human disturbance which result in a change in population
numbers and/or species content of an area.  Since impacts can be subtle
 or gross, only those impacts which are quantitatively measurable in the
 field are considered.

     The impact on an area usually has short-term and long-term com-
ponents.  The short-term component can be measured immediately following
 the disturbance.   The long-term component must be examined for duration
as well as magnitude.   Some criterion is needed to decide how much change
 is required to "recover" the disturbed areat (i.e., the quality of the
 recovery), and how long the recovery will take.  However, the product of
 the recovery can vary.  If the land and vegetation return to a different
 condition, a new wildlife community may become established which is very
                                 10-1

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different from the original one.  Naturally, the rate of recovery will
vary among land types and climates.

     This raises the question of the location of the end point of the im-
pact.  Since "impact" is defined as a change, the end point is where
changes become too small to measure quantitatively.  However, natural en-
vironmental processes are dynamic; that is, they fluctuate constantly.
When this fluctuation is slow the ecosystem is considered stable, or in
equilibrium.  Likewise, wildlife communities are only relatively stable.
Thus it is both unreasonable and impossible to restore a community to its
exact original condition.  The practical solution is to restore the origi-
nal natural conditions in land and vegetation as nearly as possible, and
simulate recolonization of wildlife.  A new, but somewhat different, wild-
life community will become established in a dynamic equilibrium with the
new and somewhat different habitat.

     A broad range of human disturbances can result from the treatment of
hazardous material spills.  The least significant disturbance is probably
surface scraping of a thin layer of ground.  The impact of this to wild-
life might be unmeasurable.  Probably the greatest impact would result
from defoliation of plant life,  followed by covering the soil surface
with cement or some other mechanical stabilizer.  If done on the maximum
area size, this treatment would cause immediate local extinction or emi-
gration of the majority, if not all, of the wildlife in the area.  It
might also cause abnormally high population densities in areas contiguous
to the treated area due to emigration.

     In order to evaluate the impact of treatment disturbance in the dif-
ferent land types, a reference standard for "disturbance" is needed.
This standard will be taken as the most drastic disturbance as described
above.  In this case the immediate impact is that which follows the
treatment.  The recovery phase is defined as following the erosion or
removal of the ground covering.  For simplicity this is assumed to be
removed at one point in time.  Less drastic treatments can be evaluated
across the land types by using the same rationale applied on a lesser
scale.
                                10-2

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     The impact to the local wildlife of a land treatment is heavily
dependent on the land area that is disturbed.   The areas of concern
range from 0.01 km  to 10 km2.  These areas can be envisioned as
squares:  the smaller is 100 meters on a side and the larger is approxi-
mately 3.16 km on a side.  Since a point-to-point discussion of this
entire size range is impractical, these end points plus a midpoint area
of 1 km2 (1 km or 1000 meters on a side) will be discussed.  An addition-
al area 100 km2 is also included because it approaches an upper "end
point", at which a measurable impact can be expected for almost all wild-
life species.  These should typify the desired range of areas.

     A wide variation in habitats exists for each land type under con-
sideration.  Again, some simplification is needed in order to organize
the wide range of impacts.  This can be done by using a procedure which
has proved successful in plant ecology; i.e., describing a typical
habitat type within each land type.  The following is an adaptation of
Whittaker's system   for this purpose:

  •  Deserts include a wide range of communities.  It is appropriate to
     note that two types of desert occur in the United States:  (1) warm-
     temperate deserts, represented by the widespread creosote bush com-
     munities and the floristically rich uplands of the Chihuahuan and
     Sonoran deserts, and (2) cool-temperate desert scrub, including the
     sagebrush semidesert of the Great Ba.sin.  The floras of both these
     desert types share a scrubby habitat.  Also, in both a lack of
     moisture is critical to the maintenance of the various habitats.
     Thus deserts can be typified as those areas of extremely low
     annual rainfall.

  •  Prairie (or grassland) includes the great prairies, plains, and
     desert grasslands of the United States.  Despite reduction of
     vegetation structure to a single major horizontal stratum, plant
     species diversity in grasslands can be high compared with most
     forests.  These are areas of relatively low rainfall  (but more
     than  deserts)  and experience  a broad  range  in mild  temperatures.
                                10-3

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•  Deciduous forests grow in modera,tely humid, continental, tem-
   perate zone climates, with summer rainfall and severe winters.
   Broad-leaved deciduous trees (oak, beech, maple, ash, basswood,
   etc.) are dominant in forests with trees 30 to 40 meters tall.
   Animal life of temperate deciduous forests is abundant but
   varies according to the season; diversity of plant and animal
   species is moderately low to moderately high.  Deciduous for-
   ests are extensively developed in the eastern United States.

C  Coniferous (evergreen) forests occur in varied temperate zone.
   circumstances.  Extensive needle-leaved evergreen forests occur
   in continental climates of the western United States, and in
   places where soil characteristics, or fire frequency, or both,
   favor pines over broad-leaved trees in the milder climate of
   the eastern United States.  Coniferous forests are dominated
   by pine, fir, spruce, etc.  A special type of coniferous for-
   est is the subarctic-subalpine needle-leaved forest of the
   cold edge of the climatic range of forests.  These areas exist
   in the northern part of North America and exist to the south
   at higher elevations in mountain areas.

a  Mountain areas can be categorized as vertical extensions of
   other land types, as well as those areas which are exclusively
   non-forested aeolian or alpine regions.  Aeolian mountain areas
   are almost never the sole habitat of animals using them.  There-
   fore, wildlife responses detailed in the discussions of the
   other land types are applicable.  When mountain areas are ex-
   tensive, they may be very similar to tundra, and that land
   type should be referred to.  The reader  is referred  to these
   specific sections for treatment of the wildlife of mountain
   habitats.

•  Turidras are the treeless arctic plains.  The vegetation forms
   are varied and there are often complex patterns of dominance  by
   dwarf-shrubs, sedges and gresses, and mosses and  lichens.   In.
   many tundras the deep layers of the  soil are permanently  frozen,
   and only the surface soil is thawed  and  becomes biologically

                             10-4

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   active during the summer.  In many of these communities, re-
   peated freezing and thawing of the soil separates rocks from
   finer soil materials and arranges the rocks in parallel strips,
   or in networks with polygonal cells; striking internal pattern-
   ing of the plant communities in relation to soil differences
   results.  Vegetation cover decreases toward the sparse lichen
   communities, rock fields and ice of high elevations.

•  Coastal inter-tidal marshland can be salt-water or estuarine.
   These areas, especially salt-water marshes, are extremely rich
   energy sources.   Like prairies,  they are limited in vertical
   structure.  The plants of salt-water marshes are herb and forb-
   like.   Marshes are not usually extensive,  but are rather patchy in
   occurrence, or form a narrow band along a lake or coast.

•  Agriculture is unique, being the substitution of a usually monotypic
   community for one or more natural plant communities.  Agriculture
   is practiced in nearly all climates,  although many hot and cold
   areas are not yet occupied fully.   Agriculture can be characterized
   as managed fields with generally low vegetation (under 12 feet)
   dominated by 1 or 2 cultivated plant species.  The most common
   secondary species are those generally considered "weeds," i.e.,
   introduced herbs.  Agriculture is extremely widespread .in the
   United States except where climate and/or terrain are exceed-
   ingly harsh.

•  Suburban land types are best described as  those areas which make
   up areas of human habitation.   Like agriculture,  these areas are
   extremely widespread.   The numerous roads  and human activity
   associated with this land type severely restrict  the type of
   wildlife which can exist.   The human dwellings are usually asso-
   ciated with exotic introduced  plants  and/or weedy species.   As
   with agriculture,  this land type is an imposition of a new com-
   munity upon a previous and older natural community.   This favors
   a low number of species,  but with high densities.
                              10-5

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     Some species have extremely low population numbers and must be
examined individually to assess potential cleanup impact.   Identification
of these sensitive species can be obtained from Federal and State lists
                                     5 22
of threatened and endangered species. '    State lists are to be pre-
ferred since they often include recent information on steps which have
been taken to protect the species.   State agencies also usually have
recent literature and staff knowledge which may bear on the problem.

     If a habitat which supports such, a species is disturbed, several
things may be done to speed up the recovery phase for the animal.  This
may be necessary for disturbances to rare species.  For example, the
Trumpeter Swan was close to extinction (about 65 birds) in 1935.   Areas
where these birds breed were designated as off-limits to hunters.  Also,
additional food was made available at these sites in winter.  Finally,
the birds were introduced to other potential breeding sites.  Due to
these steps, the population had recovered (to about 915 in the U.S.)
by 1976.   Other direct steps can be taken to accelerate faunal recovery,
that is, increasing the rate of vegetative recovery.

     Faunal recovery is strictly related to the recovery of the vegeta-
tion.  The fauna cannot normally respond before the vegetation has
done so.  There are three components of the vegetation which are particu-
larly important to animals.  The first is the plant species which colo-
nize a disturbed area.  These are of especial importance to the herbivores.
The other two components are vegetative height and density, i.e., the
vegetational structure (see Emlen  for an exception).  All three of the
above components will change over time in the successional processes of
the vegetation.  Faunal recovery must, to some degree, be an upward pro-
cess in terras of the food chain.  Carnivores cannot colonize an area
until their prey is available.  Since abundances may  increase  slowly by
reproduction, or quickly by invasion, it is difficult to predict a  re-
covery  for animals at the top of the food chain.  However,  these effects
can be mitigated for those predators which can utilize a wide  variety  of
prey, so that food can be caught during several stages of the  vegetation
succession.
                                 10-6

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      Once vegetational succession has produced a new climax community,
 the more similar the new vegetation is to the original, the more similar
 the new fauna  should be to the original fauna.  This does not require a
 vegetation be  established that is identical to the original.  All that
 should be required is an approximation of the original vegetation which
 provi-es the same resource value in terms of food and structure.  The
 critical questions to wildlife restoration are the "quality" and duration
 of vegetation  recovery.
                                                               25
     Plant succession has been well studied by plant ecologists   but
the faunal community succession process which occurs in nature has not
been studied as much.   As plant succession occurs,  multiple feedbacks
are possibly among and within plants and animals (not to mention soil
content changes, ground-level temperature regime cahnges,  etc.).  The
network can be extremely complicated.   However,  faunal changes can be
closely examined with respect to plant succession,  and different animal
species will show greater or lesser facility for recovery.

      In most cases some species which were not among the original fauna
of the area will move in during part of the vegetative recovery.  These
species will probably move out of the disturbed area as the habitat
changes toward one more similar to the original one.  This causes a
decrease in species diversity as the climax of the faunal succession is
 reached.  The  pattern of plant species diversity in succession  emerges
as a  rise from the start of recovery to a pre-climax peak, and  then a
 leveling off at a slightly lower level as the dynamic equilibrium of
                  Q
the climax ensues.
     The few studies that have been done on faunal succession draw
evidence from  the fossil record and emphasize evolutionary (very long
term) time.  Of concern here is ecological, not geological, time, i.e.,
a relatively short period of time during which succession may occur,
                     19
but evolution  cannot.    Thus this discussion emphasizes the responses
which are expected from individual species, rather than faunal  succession.
                                 10-7

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10.2  EFFECTS ON BIRDS
     Much information must be integrated in an examination of impacts on
birds.  Unfortunately, much of this information dealj with particular
species, making generalizations difficult.  However, in order to understand
impacts on birds some generalization is necessary, as a discussion of each
species individually is impractical.  Therefore, impacts are described
for groupings of birds which share some general life history and/or feed-
ing characteristics, or are closely related.  These groupings are examined
for short-term effects (immediate impacts) and long-term effects (recovery
phase), then each land type is examined for specific short- and long-term
effects.
     Measurement of a change in the numbers, or population, of a bird
species is not an easy or unambiguous process.  First the term "popula-
tion" must be defined in some way which is not necessarily land-area de-
pendent.  Once this is done a census method must be picked from those
which have been shown to be accurate. '    But even after a standard for
measurement is chosen, and the data taken, it is still necessary to put
the measured impact into context.  What is really desired is the effect
on the  local species.  This effect can only be ascertained by having a
local wildlife expert analyze the data for the disturbed area and gener-
alize the measured impact into an impact value based on local abundances.

10.2.1  Short-Term Effects
     In general, a disturbance to an area will be much more serious to
permanent residents than to migrators.  This is especially true where the
disturbed area is along a migration route.  If .adequate alternative routes
of migration are available there may be no quantitative impact.  Where
only one route is possible, if food is not taken from the area by the
migrants the impact may be very slight.  However, once alternative routes
of travel are used, it may prove very difficult to reintroduce the dis-
turbed  area as a part of the migration route.  This will depend on how
many of the migrators are lost, whether the alternative route is really
as adequate as the original, and whether the route is learned or innately
known.  The slow rate of reintroduction of residents and migrants who
                                   10-8

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feed on an area should be slightly greater for the more mobile migrant
populations.
     The seasonality of a disturbance is of extreme importance to birds.
In general, disturbances in the spring will have a much greater initial
impact than those in other seasons for two principal reasons.  The first
is that the breeding season occurs in the spring for most American bird
        24
species.    The second reason is that the spring is also a very critical
time of growth for plants.  Naturally, a disturbance in another season
can affect spring conditions; however, most bird species can react to ad-
verse habitat conditions before breeding occurs.  For example, they may
nest elsewhere, or at least nest in lower densities.
     Among most birds, a disturbance to the breeding grounds is generally
more serious than an equal disturbance to the wintering range.  Many
birds hold territories during the breeding season, but form flocks during
the winter.  Flocks can lose members to other flocks when food is scarce,
or can remain cohesive at a small cost to each of the members.  This is
not true of the destruction of breeding territories.  The area lost here
will almost always result in a lower number of breeders.  Thus an immediate
impact is more likely to be of greater magnitude when breeding habitats
are destroyed.
     Some birds feed away from the nesting area or hold feeding terri-
tories around the nesting area.  The nesting can be done in tightly
packed colonies or, when food is taken at some distance away from the
area of the nest, in looser aggregations.  Those species which hold
feeding-nesting territories are much more spaced out.  Obviously, dis-
turbance of a colonial breeding area will affect more birds than the
same area disturbance to a feeding-nesting territory.
     A strong correlation between body size and feeding-nesting terri-
tory size has been shown for many bird species.    Thus a disturbance
of a given-sized area will usually affect more members of small species
                                                 2                         ~
than larger ones.  The loss of an area of 0.01 km  can cause the loss
of six song sparrows' feeding-nesting territories.  However, the same
area is only 0.25 percent of a red-tailed hawk's feeding-nesting terri-
             2
tory.  A 1 Ion  area is roughly a quarter of the size of a red-tailed hawk's
                                    10-9

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territory, and is a reasonably large area in terms of most smaller birds.
                                                                         2
In any case, there can be little doubt that the loss of an area of 100 km
from the breeding range of almost any species will have a measurable impact.

10.2.2  Long-Term Effects
     Birds respond very quickly to habitat changes due to their high mo-
bility.  When the proper conditions prevail, bird dispersal is facilitated.
However, different life histories will cause some differences.  Size dif-
ferences will also be critical, as larger birds can expand their terri-
tories more easily than smaller birds.  The following differences also
hold for some broad groups of birds.
    • In general, migrators being more mobile than permanent residents,
will colonize areas more quickly.  However, where migration routes and
summer/winter grounds do not border on a suitable area, colonization can
be much slower.  Permanent residents have an advantage in being able to
establish themselves at a time when migrators are not present.  Some
species, such as the Trumpeter Swan, can migrate or not, depending upon
food resources, and will recover accordingly.
     The area used for breeding grounds by migrators may spread at a
somewhat more rapid rate than that of permanent residents.  However, the
choice of wintering grounds is  likely to be even more flexible.  The par-
ticular migratory species which uses an area will probably depend on the
successional  stage of  the vegetation.  Some species of migrators may
colonize new  breeding  habitats more quickly than others.  These effects
may not have  corresponding effects on the wintering range except  for a
change in the number of  young present.  However,  since the breeding ter-
ritories must be reestablished  each year, complicated variable changes  in
the species pattern on the breeding grounds may occur.  The damping of
these  changes may extend beyond the vegetative recovery phase.
     Feeding  flocks are  apt to  be  rapid  colonizers  since  their foraging
method entails  high mobility  and allows  them to  exploit  a thinly  spread
          f\
resource.    Birds with feeding  territories  usually colonize from  a
"leading  edge"  of the  population.   This  movement  is necessarily slower.
The  recruitment into  flocks may be somewhat slower,  by reproduction,  so
                                   10-10

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that even though a flock may use an area, the vegetation is not exploited
to as great an extent as by the slower colonizing territorial species.
     Competition among species may be important to recolonization.   The
first bird species to colonize an area can move in unopposed.  However,
the species which replace it in faunal succession may have to compete
with the established species in the area.  The net effect is one of pro-
longing the faunal successional process.   Just how long the succession
takes will therefore be somewhat dependent on the intensity and duration
of the total amount of interspecies competition that occurs.
     The following "trophic/niche" groups of birds contain families whose
species share trophic level and lifestyle characteristics.  Naturally,
some families have members in more than one group.  These families  are
divided into the respective groups in the following discussion.  Examples
of typical families are:
     1.  Large carnivorous birds:  American vultures, buteo hawks
         (Accipiter family), and large owls..
     2.  Medium-sized carnivorous birds:   medium-sized falcons, kites
     3.
(Accipiter family), and medium-sized owls.
Small carnivorous birds:  kestrels (Falcon family), shrikes,
and small owls.                    ;
Large primarily herbivorous birds:  grouse, pheasants, and
turkeys.
Medium-sized primarily herbivorous birds:  mockingbirds,
thrashers, thrushes, blackbirds, and quail (Pheasant family).
Small primarily herbivorous birds:  hummingbirds, titmice,
and sparrows (i.e., almost all of the Fringillid family).
Medium-sized insectivorous birds:  woodpeckers, tyrant fly-
catchers, and swallows.
     8.
     9.
Small insectivorous birds:
All sized truly omnivorous birds:
gulls.
wrens, vireos, and wood warblers.
       ducks, jays, crows, and
    10.  All sized aquatic feeder birds: plovers, sandpipers, and
         phalaropes.
     Some land types take longer to restore than others.   This can be
considered the sensitivity of the land type to disturbance.   The reasons
for sensitivity can be the magnitude of the disturbance,  the amount of
vegetative structure, and climatic conditions present, the length of the
                                  10-11

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growing season, the soil types present, and other, factors.   These many
factors are integrated in the analysis of recovery of vegetation and land
types over time.  Here, differences in the responses of the bird faunas
to the immediate disturbance and the subsequent recovery of the different
land types are described.
     Table 10-1 gives examples of bird species from each trophic/niche
group in each land type which yield a measurable impact if the maximum
disturbance has been made on the specified (or larger) land areas.  The
table uses ;area size differences among groups of birds to show how the
groups are affected.  This should not be equated with the qualitative
"importance" of a species.  For example, more robins would be lost than
red-tailed hawks for a disturbance to a habitat for both.  But the hawks
may be more "important" than the robins in terms of numbers in existence
or aesthetics.
     The table assumes that at least ten breeding territories must be
lost to a species before impact can be measured.  No literature is
available upon which to base an estimate of the number of breeding pairs
which must be removed from a habitat to yield a measurable impact,
The figure of ten was chosen because it represents a number at which
large and/or uncommon species will begin to show a measurable impact.
The figure of ten is thus a minimum.  The real figure should be higher
for many species.  However, lower figures should seldom occur.  A
further assumption is made that measurement is solely on a local scale.
Bird breeding territory area is used because the breeding grounds are
of the greatest immediate importance to the multiplication (reproduction)
of most populations.  Bird breeding territories may vary with food
resources in some cases.  However, breeding area should generally be
less variable than any other type of defended area used by individual
birds.

     10.2.2.1  Deserts—
     The imp'act of a disturbance in deserts will be greatest for  small
herbivores, medium  sized  insectivores,  and all carnivorous birds.  An
added impact on carnivores is the  loss  of a great diversity of reptilian
                                   10-12

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Table  10-1.
Examples of bird  species  impacted  by  maximum  disturbance
to  specified types  arid  sizes  of land  areas.
MAJOR GROUPS
1. LAND TYPE
DESERT
Large Carnivores
Medium Carnivores
Small Carnivores
Small Herbivores
Medium Insectivores
PRAIRIE
Large Carnivores
Medium Carnivores
Small Carnivores
Large Herbivores
Omnivores
DECIDUOUS FOREST
Large Herbivores
Medium Herbivores
Smal 1 Herbi vores
Medium Insectivores
Small Insectivores
CONIFEROUS FOREST
Small Herbivores
Medium Insectivores
Small Insectivores
TUNDtfA
large Herbivores
Aquatic Feeders
COASTAL INTER-TIDAL
Medium Herbivores
Small Herbivores
Medium Insectivores
Small Insectivores
Omni tore:
Aquatic Feeders
2. LAND USES
AGRICULTURE
Large Carnivores
Medium Carnivores
Small Carnivores
Medium Herbivores
Small Herbivores
SUBURBAN
Medium Herbivores
Small Herbivores
Medium Insectivores
Omnivores
SIZE fir LAND AREA
0.01 km2












Franklin's gull




Least flycatcher
White-eyed vireo









Song sparrow
Bank swal low







Robi n
House sparrow

Cardinal6
Song sparrow
Cliff swallow

1 km2




Loggerhead shrike
Black-throated s,parrow
Ash-throated flycatcher




Greater prairie chicken
Common crow

Ruffled grouse
Baltimore oriole
Black-capped chickadee
Acorn woodpecker
Tennessee warbler

Pine siskin
Western flycatcher
Olive warbler

Willow ptarmigan
Whimbrel

Yellow-headed blackbird
Marsh wrens
Tree swallow
Yellow- throat
Pintail
Willet



Loggerhead shrike
Mockingbird
Chipping sparrow

Mockingbird
House finch
Black phoebe
Blue jay
10 km2




Elf owl





Sparrow hawk
























Barn owl
Burrowing owl
Sparrow hawk







100 km2


Red-tailed hawk-
Prairie falcon




Golden eagle
Prairie falcon


Common raven































   Territory sizes takjn from Welty  and Schoener  or estimated from sizes of similar species.

   Species nomenclature follows Peterson,1 where scientific name;, are also qiven.

   Member of the sparrow family.
                                        10-13

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prey.  Large- and medium-sized herbivores occasionally occur in desert,
usually on its fringes, as is true of most small insectivores and omni-
vores which live in or near deserts.  The desert itself is not the sole
habitat of these species, and impacts are thus lessened.
     Resident desert bird faunas should contain a high proportion of
specialist species which have low population densities.  These birds
will be extremely slow to respond to most recovery situations.  The
generalist species which do occur in desert can usually be expected to
expand their numbers beyond the normal level upon colonizing a disturbed
area.  In this particular habitat the presence of generalists in abundance
will probably further retard reeolonization of specialists to a measurable
degree.  Management may be extremely useful in this unusual case.

     10.2.2.2  Prairies--
     Prairies are remarkable for having a distinct lack of vegetative
height.  Large herbivores and omnivores are the groups most impacted by
a disturbance here.  These are  closely followed by carnivores of all
sizes.  Carnivores feed not only on bird prey on prairies, but also on
the  high populations of mammals which are common herbivores.  Medium-
sized  and small herbivores, while not as diverse on prairies  as  in other
land types, may still  be very abundant.  Once again,  as smaller herbi-
vore*  are examined; the  impact  of a disturbance is usually magnified.
Medium-sized insectivores often feed over prairie, but seldom nest there.
Thus the impact to this  group should be reduced.  Even less  impact should
be seen in aquatic feeders, who use prairie areas as  stopping-feeding
sites  during migration.
     Prairies  contain  an imbalance  of generalist  species, mainly due  to
the  high  carnivore and omnivore diversity.  Thus  the  recoveries  of prairie
bird faunas  are  largely secondary effects,  since  both the above  groups
depend to some extent  on animal prey.   Carnivore  recovery may lag far
behind the vegetative  recovery.  The omnivores,  on  the other hand,  are
 generalists  and  will  recover more quickly.  Much more omnivore feeding
 than breeding occurs  in prairie areas,  also facilitating  the return of
 this group.   The remaining breeding species are herbivores which are
                                   10-14

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generally mobile species for their size.  They will recover relatively
quickly.

      10.2.2.3  Deciduous Forests--
      Deciduous forests have good diversity and abundance of herbivores
and insectivores of all sizes.  These groups will bear the major impact
of a  disturbance in most cases.  Here also large and medium sized
carnivores will occur mainly where there are breaks in the forest, and
be impacted in proportion to the disturbed area of the forest breaks.
Small carnivores and omnivores, while lacking in diversity in these
forests, may be locally abundant.  These last two groups should be wide-
spread where they occur, thus lessening potential .impacts upon them.
      Deciduous forests are generally richer in bird fauna than coniferous
forests and relatively higher proportions of specialist species occur.
Thus, the faunal recovery will take longer in deciduous forests.   However,
these forests also have the advantage of being extensive, so colonists
are available.  These bird faunas may be extremely sensitive to dis-
turbance, since the specialists may have a more "patchy" distribution
as well as lower population densities.  Because of their size and lesser
mobility, the smaller herbivores and insectivores may be very slow in
recolonization.

      10.2.2.4  Coniferous Forests—
     The disturbance of coniferous forests should impact small herbivores
and insectivores of all sizes to the greatest degree.   A great abundance
and diversity of these groups occur here.  In breaks in the forest,  large
and medium-sized carnivores occur and will be impacted where the breaks
are disturbed.  Coniferous forest supports relatively less small  carni-
vores, large and medium-sized herbivores, and omnivore diversity.   Where
these groups occur, however, they may do so in abundance, and thus be
impacted.  Again,  these last groups (except the small  carnivores)  are
more  likely to occur in breaks in the forest.
      Coniferous forests tend to contain a relatively limited fauna
compared with the other land types.  However, the number of specialists
                                   10-15

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and generalists is usually evenly balanced.  Naturally, the generalists
will respond to vegetative recovery more quickly.  However, since coni-
ferous forests are generally extensive, surrounding forest areas are
almost always present to provide colonists.  As vegetative recovery nears
completion, more and more specialists will move in to supplement the
labile generalists.

     10.2.2,5  Aeolian Mountain Peaks—
     A disturbance to a mountain-alpine habitat will affect only those
few birds which have adapted to this barren land type.  An example of
one of the few species of birds which are specialized for this type of
habitat are the Ptarmigans (in the Grouse family).  During winter,
alpine birds move to lower elevations, and live in other land types.
Herbivores of all sizes will receive the greatest impact from an environ-
mental disturbance, because of the disruption in their food supply.
Large and medium sized carnivores may use alpine areas for hunting and
breeding, but carnivores will be impacted to a lesser degree due to
their ability to move into other types of habitat below treeline.  The
other trophic/niche bird groups should rarely occur in alpine areas and
thus receive no impact from a disturbance to it.
     Due to specialization of herbivorous alpine birds and the patchy
and disconnected nature of the alpine habitat, recovery from a disturbance
will be an arduous process.  Mountains are to a  large extent "islands"
                               25
separated by a "sea" of forest;   therefore, recolonization of alpine
areas may only be possible from within the original population.  Many
alpine birds winter in nearby forests, thus, the more isolated a mountain
is, the longer it will take for colonists from other mountains to arrive.
Since large and medium carnivores of alpine areas are generalists they
will recover more quickly.  However, they will only be able to recolonize
alpine areas as their prey also recolonizes.

     10.2.2.6  Tundra Areas—
     The tundra is commonly only the summer range of  species which  breed
there.  However, a group  of large herbivores  (ptarmigans)  are resident
on tundra, and thus are subject to  the greatest  impact of  any disturbance.
                                    10-16

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 Impact on  the principal'summer breeding migrants, the aquatic feeders, is
 also very  serious.  Many of  these birds nest  in  aggregation, so impacts
 are either drastic  or  considerably dampened,  depending on the location
 of the disturbance.  A few omnivores  (gull  species)  share this charac-
 teristic and nest on or near tundra.  Two large  carnivores  (the snowy
 owl and gyrfalcon)  feed on tundra and breed nearby.  These  last two birds
 have large ranges which help to mitigate any  impact  upon them.
     Tundra bird faunas are  largely migratory, so that bird recovery can
 be relatively rapid.   However, since the bulk of breeding for the aquatic
 feeders occurs here, the recovery of breeding populations must generally
 follow the recovery of food  resources.  The yearly freezing of the. ground
 does not encourage  invertebrates, so that more vegetation must be eaten.
 The only resident birds, the large herbivorous ptarmigans, are also
 closely tied to vegetative recovery.  Where tundra occurs it is usually
 extensive, so that the  bird  fauna can recolonize an  area easily.

     10.2.2.7  Coastal  Inter-Tidal Marshlands—
                                               OC
     Marshlands are usually  rich energy sources   and therefore all non-
 carnivorous groups except large herbivores are usually represented.
The small  insectivores  and aquatic feeders are especially noticeable,
 the former even more so in fresh-water marshlands.  Since those species
which live in marshes are pften restricted to it, they will be impacted
 severely by a disturbance.    Large- and medium-sized carnivores which
frequent marshes usually include other areas  in their hunting range,
or can easily do so.  They are therefore less impacted.   Many aquatic
feeders and omnivores use marshland as stopping and/or feeding places
during migration, and can be subjected to a lesser impact by changing
their migration routes.
     Marshland bird species are generally very sensitive in terms of
faunal recovery.   A very high relative proportion of specialists occurs
here.   Their recovery is complicated by the patches in which this habitat
occurs.   If the disturbance occurs over an entire patch of marshland,
recovery will be much slower than that expected for a disturbed area
within a patch.   Thus,  disturbed area size effects are especially
                                   10-17

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important.  Size effects will be greatly magnified for smaller birds,  but
may have relatively little significance for the more mobile large- and
medium-sized carnivores.

10.2.3  Land Uses
     10.2.3.1  Agricultural Areas--
     Agricultural areas contain either breeding or feeding areas for
some members of all the trophic/niche groups except small insectivores.
However, the groups which are most impacted by disturbance of agriculture
are the medium and small herbivores and the carnivores of all sizes which
prey upon them.  Large herbivores, medium insectivores, and omnivores are
more likely to feed on agricultural areas than to breed on them, and will
usually be less heavily impacted.  Aquatic feeders are the least likely
group to be impacted since they occur only under special conditions
(excess water or ponds available).  However, the impact on this group
increases if they can breed where an area is disturbed, again a special
case.
     Agricultural land mainly supports generalist type bird species (i.e.,
those with a broad niche).  This  land type has not existed long enough for
specialists (birds with a narrow  niche) to evolve necessary adaptations
for habitat specialization.  The  few specialists found here were pre-
adapted to some special feature of the agricultural habitat, and moved
in from other habitats.  The result is an extremely resilient bird
fauna.  This fauna will follow vegetative recovery very closely.  Since
the species which occur in agricultural areas have dense populations,
dispersal from surrounding populations should send almost constant waves
of colonizers into the disturbed  area.
     A second alternative for agricultural land  is to allow it  to revert
to a state more similar to its preagricultural condition.  In this case
the agricultural condition can be considered an  additional disturbance
from which the avifauna must recover.  In order  to evaluate this particular
type of recovery, the  sections dealing with the  preagricultural land
type should be consulted.  Differences from these  land type recoveries
should not vary greatly due  to the agricultural  use of the land.  The
                                   10-13

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avifauna will change from an agricultural one to one commensurate with
the particular land type's plant succession.

     10.2.3.2  Suburban Areas--
     Suburban birds are generally birds which were preadapted to live
with humans.  This implies a versatile lifestyle and a broad niche.
The groups which would be impacted  (about equally) by a disturbance are
medium and small herbivores, medium-sized insectivores, and omnivores.
Groups which occur on the fringes of suburban areas are large carnivores,
large herbivores, small insectivores, and aquatic feeders.  These will
be lightly impacted by a suburban disturbance, if at all.
     Suburban bird faunas will also respond quickly in recovery of a
disturbed^area.  Evidence for this is abundant in almost any spreading
city.  A heavy proportion of generalists exists in most suburban habi-
     9                                                      12
tats.   In addition, rather dense populations usually occur.    These
areas are usually extensive or at least connected by corridors such as
freeways, construction sites, and/or rural human populations.  Thus
colonization can be extreme during the recovery of the land type.  In
addition, the recovery of many species need not be tied to vegetation
recovery since human dwellings provide structural diversity, and may
provide food.
     As in the agricultural land use, the alternative of allowing the
suburban area to succeed to something more like the presuburban land
type exists.. However,-this process is complicated by the presence of
semipermanent structures (e.g., buildings) which increase bird habitat
heterogeneity.  Without these structures a recovery similar to that
described in the appropriate land type is possible.  However, if suburban
land is simply deserted, species which depend on suburban structures for
nesting and/or roosting (or cover from predators) will be favored.
These will generally not be the species commonly found in the presuburban
land type, and recovery will be retarded.
                                  10-19

-------An error occurred while trying to OCR this image.

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     7.  Small omnivorous mammals:  opossums, raccoons, ringtails,
         and armadillos,
     8.  Insectivorous mammals:  shrews and moles.
     9.  Flying mammals:  two bat families.

     10.3.1.1  Large Carnivores--
     The primary immediate impact of a land disturbance to the large
carnivores should be negligible for the range of area sizes under
consideration.  An area of 100 km  is equivalent to only about one to
                              23
six mountain lion home ranges.    Due to the wide ranging of these cats,
even a much larger disturbance would be very hard to measure in terms of
a change in population numbers.  However, a secondary impact to this
animal is the loss of its prey.  Again this effect is probably unmeasur-
able, since the deer they feed on are also large animals which are
widely distributed.
     A slightly different situation exists for the other large carnivore
group, the wolves.  Measurement of populations is extremely difficult,
even for the exceedingly common coyote.  But in addition to measurement
problems, the grey (timber) wolf also forms packs.  A disturbance to the
      2
100 km  area size could eliminate (from the area) a minimum size pack of
two, but this area is only about one-tenth the home range of a pack of
eight,   so that primary impacts are impossible to assess.  Some attempt
can be made to measure the change in pack size as an indication of impact,
but this is an extremely variable characteristic.  Again, secondary im-
pacts are possible, but they are unlikely to be measurable.  In all large
mammalian species emigration is the most likely cause of a drop in popu-
lation numbers after a disturbance.

     1073.1.2  Medium-Sized Carnivores—
     Impacts on medium-sized carnivores are also difficult to measure,
Once again, the maximum disturbance to the maximum area size specified
      2
(10 km ) for consideration should not produce a measurable impact in
most cases.  The major prey of these carnivores, small herbivorous birds
and mammals, will be impacted at some area size, so that it may be
possible to get some measure of secondary impacts.  The medium-sized
                                   10-21

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carnivores are not as mobile as the large carnivores,  so that it may
be possible to estimate an impact in some cases for a disturbed area
size of 100 km2.

     10.3.1.3  Small Carnivores--
     Many of the small carnivorous mammals are nocturnal, and thus
ignored by the majority of humans.  However, it is in this group that
impacts in the larger area sizes can be measured.   Weasels will have
measurable impacts where pre-cleanup prey densities are either high,
or are moderate but extensive in area.  The other small carnivores
have larger home ranges in general and will be much harder to examine.
Secondary (prey) effects need not be examined for the groups which have
measurable impacts, since these effects are included in the change in
population size.

     10.3.1.4  Large Herbivores—
     With the large herbivores size of the cleanup area again becomes
important.  This difficulty is compounded by the ability of most large
herbivores to change home ranges seasonally  (by migration).  Local
changes in population size can probably be measured for disturbances
of the 100 km  area size.  However, these changes will probably be
measurable only immediately, for the high mobility of the larger herbi-
vores will soon reduce the possibility of finding many of the animals
which reside in the area, since they may leave it or perish.  Animals
which successfully leave the area are not defined as being impacted.

     10.3.1.'5  Small Herbivores--
     Small herbivores are generally restricted to  living  their  entire
lives in  relatively small areas.  The once  popular idea  that some small
                                                         13 14
mammal herbivores  migrate has  been thoroughly disproved.   '   .  These
animals are the most  important United States mammals  in  terms  of  species
diversity and abundance.  Their populations are easily  sampled and  moni-
tored in  most cases.   In addition,  they  form an important link between
primary producers  (plants)  and the  carnivores  which depend on  them  for
 -  ,  11
food.
                                   10-22

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      Table  1Q-2  gives  examples  of  small  herbivorous mammal  species that
 occur in each land  type  which yield  a measurable  impact  if  the maximum
 disturbance has  been made  on the specified  (or  larger) land areas and
 types.   The table indicates  the kind of  rodents and lagomorphs  (the
 rabbit  order)  which occur  in the various land types and  the general
 disturbed area sizes which will produce  impacts.  The density of these
 animals is  relatively  easy to measure.
      Table  10-2  assumes  that at least 12 to  15  home ranges  must be lost
 in  an area  before a local  impact can be  measured.  As in the bird section,
 this  home range  (area) amount is a minimum for  measurable impact, except
 for large and/or uncommon  mammals.   A special case of vole  and lemming
 home  ranges  being very small is somewhat counteracted by their excep-
 tional  movement  abilities, so that a larger  area must be disturbed for
 these species  than  just  15 home ranges.   Home range size usually varies
 with  changes in  the density  of  food  resources.  Special  cases in specific
 locations are  to be expected to vary from the predictions of the table.
      It may be that small  herbivore  species  can be used  as  indicators
 to measure the effects of  various disturbances.   Small herbivore species
 can change at  the onset  of a disturbance.    As succession  ensues,  changes
 in  species composition and density can also occur.16  When  the original
 species distribution and density reoccur, an advanced stage of recovery
 has probably been entered.   A distinction must be made,   however, between
 those small rodent species considered "pests," or those deemed undesirable
 by man, and species which  are more beneficial to man's interests.   Pest
 species are generally exterminated periodically where they exist near
 humans and impacts on them,  although measurable, may not  be of real
 concern.

      10.3.1.6  Large Omnivores—
      Large omnivores (bears)  are another group for which  it is exceedingly
difficult to measure impacts.  Only three bear species occur within  the
designated land types in North America.   These will  not  be measurably
 impacted for disturbances to the land area sizes under consideration.
For example, even without the problems  of impact measurement, the  100 km2
                                   10-23

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Table 10-2.  Examples of -small  herbivorous mammals, impacted  by maximum
             disturbance to specified types and sizes of land areas.a
   MAJOR GROUPS
   LAND TYPE

      Desert
      Prairie
      Deciduous
      Forest
      Coniferous
      Forest
      Tundra
   LAND USE

      Agriculture
       Suburban
                                   SIZE OF LAND AREAb
  0.1 km£
Cactus mouse
Pocket gophers
Pocket mouse
Harvest mouse
Grass voles
Jumping mouse

Deer mouse
Deer mouse
Phenacomys
Redback voles
Lemmings
Tundra  redback  vole
 House mouse
 Pocket gophers
 Cotton ratsc

 Black ratc
 Norway rat
 House mouse
                                                     1  km
Antelope squirrels
Kangaroo rats
Wood rats
Jackrabbits

Ground squirrels
Prairie dogs
Jackrabbits
Tree squirrels
Flying squirrels
Chipmunks
Cottontail rabbits

Marmots
Tree squirrels
Flying squirrels
Chipmunks

Showshoe hare
 Ground squirrels
 Jackrabbitsc
    a  Home range sizes  taken  from  McNab,    Vaughn,    and  Burt and
      Grossenheider,4 or estimated from home  range  sizes  of  similar
      species.   Nomenclature  of the genera  and  species  follows  Burt
      and Grossenheider,4 where scientific  names  are also given.

    b  For land areas of 0.01  km2 or less no small mammal  herbivore
      should be impacted, above 1  km2 all  should  be impacted.

    c  Denotes pest species or genera.
                                  10-24

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 area size is only about half the size of the Grizzly bear home range.23
 However, the actual effects on these animals can be serious since they
 art. restricted to isolated patches of wilderness areas,4 and emigration
 may not always be possible.

      10.3.1.7  Small  Omnivores—
      The impacts from disturbance of the larger area sizes may be
 measurable for the small omnivores.   These animals  are generally nocturnal
 and occur in areas which are human-disturbed (mainly agricultural).   Im-
 pacts should be easier to measure for opossums,  and more difficult to
 measure for the wider ranging raccoons.17  These animals are widely dis-
 tributed where they occur,  so that immediate impacts are difficult to
 measure due to a reassortment of individuals during movement away from
 the disturbed  area.

      10,3.1.8   Insectivores—
      Insectivores  are small mammals with  extremely  limited mobility.
 Like small  rodents, they are  closely  tied to  their  area  of residence
 and can  be  expected to be measurably  impacted in disturbances to  all  but
 the  smallest land  area sizes.  In'addition, these animals depend on insect
 and  other small  animal prey,  so that  a disturbance  to the prey can cause
 as great an impact as a  direct disturbance to the insectivores themselves.

      10.3.1.9   Flying Mammals—
      The impact  from  a disturbance on the flying mammals  (bats) is
 roughly  comparable to that on insectivorous birds.  These nocturnal
 animals have excellent mobility, but are most sensitive to disturbances
 to breeding areas.  In addition, many bat species are colonial, so the
breeding areas are patchy in occurrence.   A disturbance of the smallest
designated area size could have a measurable impact on a breeding colony.
On the other hand, much  larger feeding areas would have to be disturbed
to yield a measurable impact.  Bat species occur in several types of land
areas.
                                   10-25

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10.3.2  Long-Term Effects
     The recovery phase of a mammal community is closely tied to the re-
covery of the vegetation.  The food value of the vegetation is an impor-
tant determinant in mammal recovery.  In addition, the amount of cover
provided by the vegetation is important to small mammals which are subject
to avian predators.  The vertical height of the vegetation is actually of
less general importance since relatively fewer mammals are canopy dwellers
than ground dwellers.  The main benefit provided by the vegetation height
is the amount of feed which exists at each level for herbivores and om-
nivores.  Another extremely important benefit for some prey species is
cover.6  Naturally, the habitat beneath the vegetation should vary with
vegetative height and density.  Therefore an important indirect benefit
is provided.

      10.3.2.1  Large Carnivores--
      Large carnivores will respond  to the recovery of their prey following
a disturbance.  The functional response of carnivores, an  increase  in  the
exploitation of prey, can be  practically  instantaneous.  However, the
numerical response, an  increase  in the number of  predators in an area,
is  necessarily slower.   This  response can occur both  through  immigration
or  large carnivores to  the recovering area   and  by reproduction, but
the latter process  is much slower  and may be masked by  immigration.
Since large  carnivores  are not measurably impacted by a  disturbance,
their recovery in an  area will be  a qualitative rather  than a quantita-
tive change.  Qualitative changes  can be  measured, but  only on a very
restricted  local  scale,  so that  the measurements  are  of questionable
significance in  assessing  impacts  to the  individuals  of highly mobile
species. The pertinent point is that  the quality of  the local area
changes when the animals leave.

      10.3.2,2  Medium-Sized Carnivores--
      The recovery of medium-sized carnivores should share the same
 characteristics as the recovery of large carnivores,  but on a more local
 scale.  Since medium-sized carnivores have less mobility, they will be
 slower  in responding to prey in the interior of a large disturbed area.
                                      10-26

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 However,  the numerical  response  will  still  be made mainly by  immigration.
 Again,  population changes  of these  animals  will  be limited by changes  in
 the populations  of their prey.   The medium-sized carnivores are also
 unlikely  to  be impacted measurably, so  that recovery will only be a
 qualitative  process.

      10.3.2.3 Small  Carnivores--
      Disturbances  to  the larger  land  area sizes  will have measurable
 impacts on the small  carnivores, and  therefore "recovery" can  be demon-
 strated quantitatively.  Since these  carnivores  are less mobile than the
 larger classes, much  of the numerical response must come from  reproduc-
 tion.  Small  carnivores  should follow fluctuations in prey density much
 more  closely  than  larger carnivores due to  their more limited mobility.

      10.3.2.4  Large  Herbivores--
      For  large herbivores, size effects are again of critical importance
 in  evaluating recovery  from a disturbance and their recovery will be
 qualitative rather than  a measurable change.  Since the large herbivores
 are highly mobile  (some are migratory),  the rate of movement  back into
 an area will depend on the reestablishment of edible vegetation.   The
number of large herbivores that a disturbed area can support  will  change
 gradually, and some disturbed areas may actually support higher densities
than originally existed.  This will occur where  the plant food is
actually denser and/or of better quality during  recovery than  in  the
 climax community.
complex.
      12
     10.3.2.5  Small Herbivores--
     The recovery phase of small herbivore populations can be extremely
        3,12
              Interspecies competition effects will be important in many
cases.~~  The recovery of small herbivore numbers should depend on both
immigration and reproduction.  Small mammals are noted for their ability
to respond reproductively, but dispersal abilities can also play a
key role in their population dynamics.    The recovery of small herbi-
vores should be very closely tied to changes in the vegetation, and
several distinct successional communities may occur.
                                     10-27

-------
     The immediate disturbance to an area may well create ideal conditions
for invasion by small "pest" rodents.  These animals may aid plant suc-
cession by cycling nutrients in the community and thus provide a beneficial
function.    However, competition may occur among "natural" species attempt-
ing to immigrate and could have a very detrimental effect.  Careful manage-
ment of small mammals can provide means for facilitating community recovery.
Predators can be introduced to dampen outbreaks in small herbivore popu-
lations, if control measures are needed.  Small mammal populations can
provide an index for monitoring community recovery of both the flora and
              i.
fauna.
     10.3.2.6  Large Omnivores—
     Because of their great mobility and large home range sizes, the re-
covery of large omnivores (bears) after a disturbance to an area is, like
that of other large animals, a qualitative process.  The recovery of bears
is most likely to consist of them simply using the area to forage and/or
den in again.  The problem of range reduction is a serious one for North
American bear species.  Therefore real recovery may be very difficult if
the maximum area size disturbance causes the loss of one or both of a
breeding pair which live in an isolated patch of habitat.  This problem
will rarely occur, however, and can be overcome by introduction of one or
more outside individuals as appropriate.

     10.3.2.7  Small Omnivores--
     The small omnivorous mammals are for the most part opportunistic
species.  Both the opossum and raccoon are familiar species which have
managed to survive in areas of human disturbance due to their versatile
feeding abilities.  The armadillo has actually extended its range of
occurrence in the Southwestern United States during the last hundred
years.    Quantitative recovery of these species should occur closely
in pace with changes in both vegetation and prey species on the largest-
size area.  These Species are reasonably mobile and can probably spread
as well by immigration as by reproduction.
                                      10-28

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      10.3.2.8  Insectivores—
      Insectivore recovery will depend on the recovery of insectivorous
 prey,  which in turn will  probably depend largely on vegetative  recovery.
 Thus the return of insectivores to a disturbed area is a second-order
 effect and will'require a longer time lag than that which will  occur
 for the similarly impacted small rodents.   The recovery of moles  will be
 stimulated where macroinvertebrates are  added to the soil ,o  assist
 vegetative recovery.   Few insectivores breed more than twice  a  year, and
 many breed but once.   This will tend to  retard recovery,  as reproduction
 is  an  essential part  of colonization due to the animal's  limited  mobility.

      10.3.2.9  Flying Manrnals—
     The recovery of  bats after a  disturbance to an area  will vary with
 the nature of the disturbance.   Like many birds,  bats  require the re-
 establishment of vertical structure in the  vegetation.  However,  several
 bat species roost in  dead trees, so that  available  roosts may actually
 increase from a disturbance.   Bats  are commonly known  for their mobility.
 Several  species  migrate seasonally,  or nightly,  to  food sources.  For
 these  reasons,  bat  recovery can  occur rapidly after recovery of insect
 prey in  feeding  habitats,  and  densities may actually increase given the
 proper circumstances.  Changes  in bat populations will usually be due
 to  emigration  and immigration  rather  than reproduction,

 10.3.3   Land  Types
     Table  10-3 gives examples of mammal species other than small herbi-
vores  from  each trophic/niche group in each  land type which are measurably
 impacted if the maximum disturbance has been made to the  specified land
areas.  Large mammal groups are extremely mobile, and are therefore im-
pacted only by area sizes greater than 100 km2.  Many of  the species occur
in more than one  land type.  This phenomenon is more evident in this table
than it is for birds  (Table 10-1) and small herbivorous mammals (Table 10-2)
The greater body size and mobility of many of the mammal species may be the
reason for this.  Again, the number of home ranges lost is used in estimat-
ing the types of species lost when a given size area is disturbed.
                                     10-29

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Table  10-3.
Examples  of mammals  other  than small  herbivores  impacted  by
maximum  disturbances to  specified types  and sizes of land
areas.3
MAJOR GROUPS
1. LAND TYPE
DESERT
Large Carnivores
Medium Carnivores
Small Carnivores
targe Herbivores
Bats
PRAIRIE
Large Carnivores
Medium Carnivores
Small Carnivores
Large Herbivores
Small Oronivores
Insectivores
DECIDUOUS FOREST
Large Carnivores
Medium Carnivores
Small Carnivores
Large Herbivores
Large Omnivores
Small Omnivores
Inseetivores
Bats
CONIFEROUS FOREST
Large Carnivores
Medium Carnivores
Small Carnivores
Large Herbivores
Large Oranivores
Small Oranivores
Insectivores
Sats
TUNDRA
Large Carnivores
Medium Car-sivoren
Small Carnivores
Large Herbivores
Large Omnivores
2. LAND USES
AGRICULTURE
Medium Carnivores
Small Carnivores
Large Herbivores
Small Omnivores
Insectivores
Bats
SUBURBAN
Small Omnivores
Bats
SIZE OF LAND AREA
0.1 km2


. b
Yuma myotis


Vagrant shrew


Pacific mole b
Little brown myotis

Shortfall shrew .
Mexican freetail bat0



Eastern mole
Evening batD
h
Pallid bat0
! km2








Armadi llo


Least weasel


Least weasel






10 km2


Hoqnose skunk


Spotted skunk
Opossum


Long-tail weasel
Opossum


Short-tail "weasel
Opossum


Short-tail weasel

Spotted skunk
Opossum


Opossum

-100km2

Mountain lion
Kit fox
Mule deer

Coyote
Red fox
Pronghorn

Mountain lion
Lynx
Marten
Whitetail deer
Slack bear
Raccoon


Grey wolf
Lynx •
Marten
Mule deer
Grizzly bear
Raccoon


Grey wolf
Arctic fox
Barren ground caribou
Grizzly bear

Red fox
Mule deer
Raccoon


Raccoon

       3  Home ranqe si^es  taken from McNab,  Vaughn,23 and Burt and Grossenheider,  or estimated from home range sizes
          of similar species.  Nomenclature of the genera and species follows Burt and Grossenheider»H where scientific
          names are also given.
       0  Bats, although migratory, appear in the smallest area category because of their colonial or semicolonial
          nesting :haracteristics.
                                                 10-30

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     Impacts can be defined more precisely as smaller mammals are ex-
amined, due to their reduced mobility which smaller size usually causes.
Therefore, in the discussion of the mammal fauna, small mammals are
emphasized.  In addition, some land types, notably agricultural and
suburban, support more "pest" specimens than others.  A special con-
sideration regarding these land types is the desirability of restoring
these mammals.

     10.3.3.1  Deserts—
     The single most important and prevalent group of mammals in the
desert habitat is the small herbivores.  Although large, medium, and
small carnivores, large herbivores, and bats may occur in deserts, their
diversity does not approach that of the small herbivores.  When a desert
area is disturbed, some measure of the impact on small mammals is often
obtainable.  However, the impact must be '.nferred from a comparison of
the disturbed area with some nearby area.  The return of herbivores will
keep pace with the vegetation return, a distinctly slow process.  Deserts
are continuous, so that colonization by both dispersal and reproduction
can occur from the edges of the disturbed area.  Intermediate faunal com-
munities are not expected for succession in most desert disturbances.

     10.3.3.2  Prairies—
     The prairie habitat supports a diversity of large herbovores.  Car-
nivores of all sizes as well as small omnivores may occur here, but by far
the most abundant and diverse group in prairies is the small herbivores.
The importance of small herbivores in this habitat is greater than in any
other habitat except tundra, where their importance is roughly equal.
A disturbance to prairie will certainly have a measurable impact on some
small herbivores for all but the smallest area size.  Therefore some
measurement of the recovery may be possible.  The recovery of the small
herbivores may involve changes in the densities and distributions of the
species present, as the vegetation changes.  The community recovery in
this habitat can be relatively rapid.  The continuous nature of prairies
should aid in this process.
                                     10-31

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     10.3.3.3  Deciduous Forests--
     Deciduous forests follow a pattern of response similar to coni-
ferous forests, but with some important differences.  These forests can
be expected to be somewhat richer in their mammal fauna.  The seasonal
change in canopy cover allows a richer understory of forage for both
large and small herbivores.  Bats and insectivores occur here, but are
seldom a major component of the fauna.  Medium size carnivores and
small omnivores should occur more frequently in deciduous forests.  The
response of the mammal fauna to a disturbance may again involve the
movement of large mammals out of the area, and an increase in small
herbivores.  In comparison to forests, the importance of small mammals
will be greater than in nonintensive agriculture during the recovery;
but in the mature forest, small mammals will have a similar importance
to that in nonintensive agriculture.

     10.3.3.4  Coniferous Forests—
     In coniferous forests during the recovery cycle following a dis-
turbance the number of small mammals will probably increase rather than
decrease.  Large mammals (carnivores, herbivores, and omnivores) will
usually leave the area, at least until restoration is well under way,
and then return.  Thus in coniferous forest, impacts are very difficult
to measure but: recovery is easier to assess.  This habitat is ideal for
the use of small mammals as indicators of recovery.
     Bats and insectivores are relatively unimportant components of the
mammal fauna, though they do occur in coniferous forest.  If insectivores
are present they may feed on insects which attack the dominant trees,
and thus increase their importance.  The medium carnivores and small
omnivores are more likely to occur at the forest border, and thus will
recolonize from other habitats.   The continuity of coniferous forests
should help most species recolonize from undisturbed areas.

     10.3.3.5  Tundra Areas--
     In tundra, small herbivores are key species to the ecosystem
economy.    Small carnivores depend upon these herbivores for prey.
                                     10-32

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Large herbivores, large omnivores, and large and medium carnivores may
also occur seasonally in tundra.  A disturbance to tundra will certainly
impact the small mammals measurably in most years.  The well known cyclic
fluctuations in population size of the dominant herbivores may cause an
inability to measure immediate impact in some years.  However, the
recovery phase measurements of following years will show the impact
belatedly.  Tundra is extremely sensitive to disturbance and a long
period of time is required for the vegetation to recover.  Whether
the recovery of the tundra habitat and fauna is possible in ecological
time is questionable, and predictions about recovery cannot be made.

     10.3.3.6  Coastal Inter-Tidal Marshlands--
     The marshlands are not expected to support extensive mammal faunas.

10.3.4  Land Uses
     10.3.4.1  Agricultural Areas--
     Herbivorous species are generally detrimental to man's interests
where they occur in agricultural areas.  The most common pests are, of
course, the small herbivores.  However, as the intensity of agriculture
increases, the role of small herbivores decreaises.    The other trophic/
niche groups are less frequent in occurrence in agriculture, but small
omnivores and medium-sized and small carnivores are considered pests
where animal husbandry is involved.  Large omnivores and carnivores
should occur only rarely.  Farm buildings are usually excellent places
for bat "nursery" breeding places, so that their occurrence in agri-
culture areas may be relatively high.  Insectivores are a relatively
unimportant, though occurring, component of the mammal fauna here.
     The recovery of mammals, particularly small herbivores, on dis-
turbed agricultural land can be extremely rapid.  Most, if not all, of
the responding animals will be pest species.  Most recovery problems
will involve having too many animals, at least in density, rather than
too few.   Some beneficial effects may result from nutrient cycling
through small herbivores.  However, these benefits are minimal because
of the control that man can exert on the nutrient balance.
                                     10-33

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     Here again, another alternative exists of allowing succession to
something similar to the preagricultural land type.  This is best thought
of by considering agriculture as an additional disturbance to the treat-
ment under consideration.  The mammal recovery will be similar to the
recovery described for the specific preagriculture land type, except
where precluded by fencing.  Fences which restrict large mammal access  .
will not greatly retard recovery, but may have subtle effects.  For
example, if predators are excluded, prey species may be affected.  A
fence which excludes all ground-moving mammals will eliminate, the re-
covery for all mammals except bats, and in some cases squirrels.

     10.3.4.2  Suburban Areas—
     The suburban habitat, much like agriculture, is typified by pest
species.  No large mammals of any type and no carnivores of any size
occur regularly in this habitat.  Small omnivores, small herbivores,
and bats make up the rather depauperate mammal fauna of the suburban
habitat.  The small omnivores have principal habitat elsewhere, and
the easily measurable impact to small herbivores is probably not of
concern.  Feral domestic species, especially cats, may be impacted.
Again this is probably not of concern.  What may be very important,
however, is the increase in rodent pests, and the diseases they carry,
during the recovery.  Introduction of predators such as feral cats may
be the best technique for managing these outbreaks.  The importance of
mammals in suburban faunas is likely to be quite low, perhaps on a
par with intensive agriculture.
     If the suburban land use is abandoned, succession to a land type
similar to the presuburban one may occur.  However, the rate and quality
of this recovery will depend on whether man-made structures remain or
not.  As in agriculture, this land use itself may be considered a dis-
turbance.  Fencing out large mammals will simply cause the loss of these
animals as participants in the recovery.  However, fencing out all
ground-moving mammals may also fence surviving pest species in,,  These
pests may require control measures to avoid health hazards to humans
which might periodically occur in the fenced area.
                                     10-34

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10.4  CONCLUSIONS
     The impact of a disturbance to a species was carefully defined at
the beginning of the wildlife section, but many people may simply want
to know if the disturbance will have a significant impact on the wild-
life species.  This demands not only  a definition of impact, but also an
evaluation of impact significance.  If significance is defined as whether
or not a disturbance puts any species in danger of becoming extinct, for
the vast majority of wildlife species and the designated land areas the
answer is "no".
     The real concern must be for those species so small in numbers that
extinction is a danger to them.  These species fill the rare, threatened,
                             5 22
and endangered species lists. '    Many of these species are nearly
extinct due to man's encroachment upon their habitats.  Other species
may be on the way to extinction with or without man's help.  These two
classes of endangered species may be difficult to tell apart.  Whether
or not species which are becoming extinct should be preserved is a social
decision.  This decision, conscious or unconscious, will govern their
fate.
     Many sensitive species may not be recoverable after a disturbance
to their range.  Other sensitive species may require expenditure of a
great effort in order to assure their revival.  This must be decided
upon in each case where an endangered species is affected, presumably
on the basis of the social and political values which predominate at
the time of the disturbance.   Any effort directed to this end may also
have a fringe benefit of aiding in the recovery of the total floral and/or
faunal community.
     Table 10-4 rates the relative impacts on wildlife, immediately after
cleanup, of the maximum disturbance possible in the individual treatment
categories in each land type for the stated area sizes.  Impacts on
mammal and bird wildlife are scaled from 0 (no measurable impact) to 5
(elimination of most original species) for each combination of the three
axes of  land type, treatment, and area size with the exception of fencing,
which divides impacts on mammals and birds.
                                 10-35

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Table  10-4.
Relative impacts of land cleanup treatments on  wildlife
following maximum  possible  land disturbance.
MAJOR GROUPS
LAND TYPE
Desert
Prairie
Deciduous
Forest
Conl ferous
Forest
Mountains
(Alpine)
Tundra
Coastal
Inter-Tidal
LAND USES
Agriculture
Suburban
TREATMENT

Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
• Vegetation removal
'Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds)
Flooding
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds' only)
Vegetation removal
Soil removal, stabilisation
Fencing (birds only)

Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Sludge application
Fencing (mammals only)
Fencing (birds only), soil additive
Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
TREATMENT*
NUMBER

4^0
1
2
3-2
3-2
1
2.
3-2
3-3
4-0
1
2
3-2
3-3
4-0
1
2
3-2
3-3
4-0
1
2
3-2
3-3
1
2
3-2
3-3
1
2
3-3

4-0
1
2
5-0
3-2
3-3
4-0
1
2
3-2
3-3
RELATIVE IMPACTS FOR DIP- b
FERENT AREA SIZES (in km2)
0.01 0.10 1.0 10 100

34555
1 2345
24555
01210
00001
1 2344
23455
01221
00011
24555
1 1233
23455
01210
00011
24555
1 1223
23455
0 12 10
00011
34555
34555
12321
00011
000 00
3 4 5 5 5
34555
12321
00011
34555
345 55
Oil 11

2 4 555
22345
1 1233
0 01 22
01211
00011
1 2345
01234
0 1122
001 00
0 0.0 00
        a Treatment number 1 implies treatments 1-2 through 1-8, in general.
         Treatment number 2 implies treatments 2-1 through 2-8, in general.

         Relative impact, based on reduction in biomass
                 0 - No measurable Impact on species, < 5 percent reduction
                 1 - 5 to 35 percent reduction
                 2 - 35 to 60 percent reduction
                 3 - 60 to 80 percent reduction
                 4 - 80 to 90 percent reduction
                 5 - Original species eliminated, > 90 percent reduction
                                             10-36

-------
     The assignment of the values of the table is a subjective process     •
which necessarily assumes that all wildlife responds homogeneously to the
disturbance.  Although such an assumption is unrealistic, the table still
provides insights toward the truth, i.e., reasonable estimates of hpw a
wildlife community responds to a disturbance.  The table can also be viewed
as a ranking of treatments within each land type and area size.
     Table 10-5 estimates the relative time for recovery of wildlife from
the maximum disturbance possible and the individual treatment categories
of each land type for the stated area sizes.  The relative time to recovery
is scaled from 0 (about one year) to 5 (2 or 3 centuries).  The one-year
period is required as a baseline to measure whether a community has changed
to a greater degree than would be expected under "natural" conditions.
The 5 rating puts recovery sufficiently far into the future that it is not
reasonable to consider that recovery can take place, since evolution'may
change the community before it reaches equilibrium.
     One major assumption has been made in the derivation of relative im-
pacts:  that is, the colonization rate must remain constant for all species
in the succession^! process.  While this is not true in most individual
cases, it may be true on the average.  That is, the species in the coloni-
zation process may have varying movement rates.  But if the rates do not
vary widely, then violating the assumption may not be very serious.  The
mathematical reasoning implies a linear relationship between area size and
recovery time.  The constant colonization rate assumption is actually
another form of this assumption.              .
     Wildlife'is dependent on vegetative recovery; in fact, it is not
reasonable to try to uncouple these two types of recovery.  Therefore,
Table 10-5 includes biases which are a direct result of considering the
total environment in which the wildlife lives.  These biases are necessary
in order to improve the accuracy of impact assessment, and the computa-
tion of recovery times.
                                     10-37

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Table 10-5.
Relative  time  for recovery of wildlife following
maximum disturbance  to land and cleanup  treatment.
MAJOR GROUPS
LAND TYPE
Desert
Prairie
Deciduous
Forest
Coniferous
Forest
Mountains
(Alpine)
Tundra
Coastal
Inter-Tidal
LAND USES
Agriculture
Suburban
TREATMENT
Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Fencing (manna Is only)
Fencing (birds only)
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only}
Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
Flooding
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
Vegetation removal
Soil removal, stabilization
Fencing (birds only)
Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Sludge application
Fencing (mammals only)
Fencing (birds only), soil additive
Stabilization, asphalt
Vegetation removal
Soil removal, stabilization
Fencing (mammals only)
Fencing (birds only)
TREATMENT3
NUMBER
4-0
1
2
3-2
3-3
1
2
3-2
3-3
4-0
1
2
3-2 '
3-3
4-0
1
2
3-2
3-3
4-0
1
2
3-2
3-3
1
2
3-2
3-3
1
2
3-3
4-0
1
2
5-0
3-2
3-3
4-0
1
2
3-2
3-3
RELATIVE TIME FOR RECOVERY FORb
DIFFERENT AREA SIZES (in km2)
0.01 0.10 1.0 10 100
55555
22344
34555
21100
00000
11222
12344
2 11 00
0 00 00
45555
22333
23455
21100
00000
45555
22333
23 4 5 5
2 1 1 00
00000
34555
33455
21100
00000
00000
34555
33455
21100
00000
1 2,3 44
11222
00000
45555
11111
11111
11111
11000
00000
34555
12233
11122
1 1000
00000
    a Treatment number 1  implies treatments 1-2  through 1-8, in general.

      Treatment number 2  implies treatments 2-1  through 2-8, in general,


    b T - - 1 year
      1 - 1 to 3 years
      2 - 3 to 5 years
      3 - 5 to 50 years
      4 - 50 to 100 years
      5 -  -100 years
                                      10-38

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 10.5  WILDLIFE REFERENCES
 1.  Adams, D. L. ,  and G. W.  Barrett, 1976.  "Stress Effects on Bird Species
         Diversity Within Mature Forest Ecosystems."  American Midland
         Naturalist, 96(1), p. 179.

 2.  Belrose, F.  C., 1976.  Ducks, Geese, and Swans of North America.
         Harrisburg, Penn.: Stackpole Books.

 3.  Bunnell, S.  D., and D. R. Johnson, 1974.  "Physical Factors Affecting
         Pika Density and Dispersal."  Journal of Mammology, 55(4),
         pp. 866-69.

 4.  Burt, W. H., and R. P. Grossenheider, 1964.   A Field Guide to Mammals.
         Boston,  Mass.: Houghton Mifflin Co., 284 pp.

 5.  California Department of Fish and Game, 1976.  At the Crossroads.

 6.  Cook, Sherburne F., Jr., 1959.   "The Effects of Fire on a Population
         of Small Rodents."  Ecology 40(1), pp.  102-108.

 7.  Delacour, J.,  1954.  The Waterfowl of the World.   London: Country
         Life Ltd.

 8.  Emlen, J. M.,  1973.  Ecology:  An Evolutionary Approach.   Reading,
         Mass.: Addison-Wesley Pub.  Co.

 9.  Emlen, J. T.,  1974.  "An Urban  Bird Community in  Tucson,  Arizona:
         Derivation, Structure, Regulation."  Condor 72(2), pp. 184-97.

10,  Frauzreb, K. E., 1976.  "Comparison of Variable Strip Transect  and
         Spot Map Methods for Censusing Avian Populations in a Mixed
         Coniferous Forest."   Condor 78(2) , pp.  260-62.

11.  Golley, F. B., K.  Petrusewicz,  and L. Ruszkowki,  editors, 1975.
         Small Mammals:  Their Productivity and Population Dynamics.
         Cambridge, Mass.: Cambridge University Press.

12.  Joule, J., and G.  N. Cameron, 1975.  "Species Removal Studies I.
         Dispersal  Strategies of Sympatric Sigmodon hispidus and
         Reithrodontomus fulvescens  Populations."  Journal of Mammology,
         56(2), pp. 378-96.

13.  Krebs, C. J.,  1964.  "The Lemming Cycle at Baker  Lake, Northwest
         Territories, during  1959-62."  Arctic Inst. N.  Amer.  Tech.  Paper
         No. 15,  104 pp.

14.  Krebs, C. J.,  1966.  "Demographic Changes in Fluctuating Populations
         of Microtus californicus."   Ecological  Monographs, 36(3), pp.
         239-73.
                                   10-39

-------
15.   Krebs, C.  J., 1972.   Ecology.   New York:   Harper  §  Row,  Inc.

16.   Lawrence,  George C., 1966.   "Ecology of Vertebrate  Animals  in Relation
         to Chaparral Fire in the Sierra Nevada Foothills."   Ecology,
         47(2), pp. 278-91.

17.   McNab, B.  K., 1963.   "Bioenergetics and the Determination of Home
         Range Sizes."  American Naturalist, 97(3),  pp.  133-40.

18.   Peterson,  R. T., 1964.  A Field Guide to Western Birds.   Boston,
         Mass.: Houghton Mifflin Co.

19.   Pianka, E. R., 1974.  Evolutionary Ecology.  New York:  Harper-Row,
         Inc.

20.   Schoener,  T. W., 1968.  "Sizes of Feeding Territories Among Birds."
         Ecology, 49, pp. 123-41.

21.   Twigg, G.  I., 1975.  "Marking Mammals."  Mammal Review,  5(3), pp.
         191-16.

22.   U.S. Department of the Interior, Fish and Wildlife Service, 1976.
         Endangered and Threatened Wildlife and Plants.   Federal Register,
         Wed. 27 Oct. 1976, pt. IV.

23.   Vaughn, T. A., 1972.  Mammology.  Philadelphia, Penn.: W,B. Saunders
         Co.

24.   Welty, J.  C., 1962.  The Life of Birds.  Philadelphia, Penn.: W.B.
         Saunders Co.

25.   Whittaker, R. H., 1970.  Communities and Ecosystems.  New York:
         MacMillan.
                                   10-40

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              PART IV
            APPENDICES
APPENDIX A,  STABILIZERS
APPENDIX B,  IMPACT ASSESSMENT
APPENDIX C.  LAND TYPES
APPENDIX D,  CLEANUP TREATMENTS
APPENDIX E,  GLOSSARY

-------

-------
                                    APPENDIX A
                                   STABILIZERS
    A.I   INTRODUCTION
        This appendix contains a brief description of the major categories of
   soil stabilizers, the subgroupings of stabilizers, and the values assigned to
   the stabilizer subgroupings, land types, and land-use classes given in Table
   A-l.  The use of Table A-l is also explained.

   A.2  TYPES OF STABILIZERS
        For purposes of this report, "soil stabilizers" are defined and categorized
   to determine their practical application to soil stabilization with the land
   types defined Herein.  Stabilizers are generally classified into three major
   categories according to Ingles and Metcalf:1  chemical,  mechanical,  and physi-
   cal.   A fourth category,  chemical with mechanical characteristics,  is also
   considered here.
        Individual  stabilizers are shown  at the top of Table A-l.   The  major
   category of each is  shown by a symbol  underneath in one  of the first two
   horizontal rows;  these rows additionally denote  whether  the stabilizer is
   organic or inorganic.   The  stabilizers listed in Table A-l  are listed in
   Table A-2 with  information  on  manufacturers provided  for those that  have
   patented name.

   A.2.1   Chemical
        These  stabilizers  are  liquid  or  solid  additives to  soil that  effectively
   alter the physical  properties  of the  soil being  treated.

•  A.2.2 Mechanical
       These  stabilizers mechanically provide  sufficient  stability to bare soils
  to retard and/or prevent  soil erosion caused primarily  by wind and water,
                                        A-l

-------
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 without modifying the physical properties of that soil.  The process con-
 sists primarily of compacting soils to a density that rejects water.  It also
 includes hard surface materials, manufactured soil retention materials,  and
 chemical aids to compaction.                                                  •
      Materials used for mechanical stabilization of soils include,  but are not
 limited to,  hard surface paving such as concrete and bituminous surfaces.  .Other
 manufactured materials are meshes, polyvinyl films,  and erosion control-nettings.
 Materials such ,as burlap bags with concrete, sandbags,  rip-rap, and. cribbing
 are also means of mechanical, stabilization.                              •
      Other forms of this type of stabilizer  include  the use of. grouts,  sand,
 and other filler compounds that  can be used  to  physically fill voids in  the
 soil by absorbing water and swelling to seal off the surface area from water
 infiltration.
      Equipment used for mechanical soil  stabilization is divided into  two  types:
 (1)  compaction equipment such as pneumatic-tired rollers,  tandem rollers,  sheeps-
 foot rollers, vibratory rollers,  vibratory packers;  and  (2)  application  equip-
 ment such as concrete  pavers,  asphalt  pavers, rock spreaders,  distributors, and
 sprayers.
      A  third subcategory of equipment  also should be  considered for mechanical
 stabilization of  contaminated  areas.   This includes  equipment  such as bull-
 dozers, turn-a-pulls,  and  scrapers which are used to  construct  diversion channels,
 ditches,  berms, and retention  basins around  the  affected area.  (These structures
 would be  temporary to  collect, divert, or retard surface drainage from adjacent
 areas or  to prevent water  from leaving affected  areas and causing downstream
 contamination.)

 A.2.3   Physical
     These stabilizers stabilize soils by modifying their physical properties
with heat, electricity, and cold.

 A.2.4   Chemical with Mechanical  Characteristics
     This term applies to stabilizers that are chemically produced or chemical
compounds that bind surface soils for short  periods of time.  Primarily,  they
                                     A-3

-------
are compounds used by the agricultural industry to promote germination and
then break down once germination has begun.  They are not true "mechanical"
stabilizers because of their lack of relative permanency, and because there
are brief periods between application and stabilization during which chemical
reaction with soil occurs.

A.3  STABILIZER GROUPINGS
     The four categories of stabilizers can be further categorized into group-
ings.  These groupings define the physical characteristics and treatment types
to promote "prescription-type" treatment of affected areas within the land
types defined in the report.  These groupings are shown at the left of Table
A-l, separated by broken  lines.  To determine the rating of a grouping cate-
gory for a particular stabilizer, use the number  immediately above the broken
line for the grouping category.  The key to these number ratings is at the
bottom of Table A-l.
     The following definitions are provided for the  groupings of soil sta-
bilizers:
     Organic and  Inorganic  — the category given  to  stabilizers that  generally
     define the physical  composition  of the specific material.
     Hazard  Levels  — primarily  the degree of  safety with  which a  stabilizer
     can be  handled by  personnel during the application  periods.   It  also
     includes  the "environmental safety" of the material  after application.
     Application  —  the method  or procedure of applying  the  prescribed
     stabilizer  to a defined  area as  it relates  to  available normal  applica-
     tion  equipment and methods.
     Durability  — the  ability of a chemical  or mechanical stabilizer to
     maintain a  specified treatment for  a  prescribed time period.   This
      includes the ability of a specified  stabilizer to withstand  the effects
      of the seasonal environmental  changes.
      Vegetation Recovery Period —  the ability of a chemical or mechanical
      stabilizer to disintegrate in the normal revegetation process where
      localized natural seed sources are present  (does not include conventional
      reseeding methods).
                                       A-4

-------
A.4  RATINGS OF STABILIZER GROUPINGS
     The ratings of the stabilizer groupings noted on Table A-l are defined
as follows:
     1,  Safe — a material or technique that is generally harmless to the
     applicator, environment, and .equipment.
     2,  Handling Precautions Required — requires compliance with manufac-
     turers instructions for physical applications during handling, mixing,
     applying, and temperature extremes.
     5,  Adverse Environmental Effects — materials where there is no oppor-
     tunity for the area to recover from the use of a stabilizer without
     major rehabilitation operations.  It does not include consideration as
     a toxic substance to man.
     4,  Highly Hazardous — materials or techniques where the "cure" is
     more dangerous than the "disease."  However, these can be situations
     where highly specialized personnel can be called upon to perform this
     type of stabilization.

A. 4.1  Application
     1,   Manual  (normal) —  hand-operated.equipment that can be used effec-
     tively and is frequently available to the home gardner.
     2,   Mapual  (difficult)  — stabilizers that must be applied to a small
     area,  are caustic to operators and equipment, have difficulty staying
     in solution,  require difficult or specialized mixing techniques, or
     require special carrier substances for proper application.
     5,   Equipment (normal)  — can be applied to large affected areas using
     standard agricultural or construction equipment; restricted to areas
     where there is space for the equipment to be used effectively.
     4,   Equipment (specialized)  — requires specially, manufactured equipment
     for proper application  or standard equipment greatly modified to accom-
     modate the stabilizer to be  used.
                                     A-5

-------
A.4.2  Durability
     1,   Permanent — will remain in place without radical physical change as
     a result of normal climatic conditions.   This includes the use of chemical
     stabilizers that permanently change surface soil characteristics.  Any
     alteration of an area where this stabilizer is used would require major
     construction.
     2,   Intermediate — broad terminology meaning that natural recovery will
     eventually take place.  This also applies to stabilizers that persist
     for at least 5 years when considered for surface applications.  These
     same stabilizers can persist for periods of more than 5 years when in-
     corporated into a compacted soil.
     3,   Short Term (1 year or less) — stabilizers that effectively control
     soil movement resulting from normal rainfall.  It also includes stabilizers
     generally accepted in the agricultural industry as erosion retardents
     during germination periods of most crops.

A.4.3  Vegetation Recovery
     1,   Immediate (natural) — stabilizers which have little resistance to
     climatic conditions, and which permit natural invader plants to germinate
     and grow on disturbed areas.
     2,   Requires Seeding  (normal response) — effectively hold surface soils
     intact for a period of at least 6 months, providing the applied membrane
     is not disturbed.  Revegetation requires normal seedbed preparation and
     planting of  selected varieties.  Residues of these stabilizers, after
     they are incorporated, are biodegradable and have no effect upon the new
     seedlings.
     3,  Complete New Seedbed Required  —  stabilizers that were used must be
     completely removed or buried at  sufficient  depth with new "cold  soil"  so
     that an affected area can provide  suitable  growing conditions  for vegeta-
     tive reestablishment.
     4,  No Recovery  — change the  physical makeup of the  surface  soil  suf-
      ficiently so that the plant  zone cannot  subsequently support  any type  of
     vegetation,  and  the  stabilizer is  not effectively  altered by  normal  freeze
      and thaw conditions.
                                       A-6

-------
 A.5  LAND TYPES AND LAND USE CLASSES
      The  seven  land types  and two  land use  classes  discussed  in this report
 are shown at  the right  of  Table  A-l,  separated  by solid  lines.  To determine
 the rating of each  stabilizer on each land  type or  land-use class, use the
 letter  above  the solid  line  for  the  particular  land type or class.  The key
 to  these  letters (ratings) is located at  the  bottom of Table  A-l.  Each of
 these ratings is defined as  follows.
      a,   Preferred  — materials  that  are  short-term effective, generally
      environmentally safe  naturally  and sociologically,  and subject to the
      general  moisture and  climatic conditions of a  land  type.
      b,   Acceptable as  an  Alternate  — basically the same characteristics as
      those classified "preferred," however, because of the effectiveness of
      the  material or application procedures they should  not be considered
      exclusively for stabilization of affected  areas.
      c,   Not  Acceptable  (last  resort  measure) — materials that should not be
      used because of the resultant damage, primarily to  the natural environ-
      ment.  When there  are situations where the  natural  environment cannot be
      protected  from irreversible effects of "accidental  spillage," these
      materials  may  be used.   This assignment is  also made to materials when
      applied  to various  land  types because of the variability within the land
      types  themselves.   For example,  "prairies"  can  be divided into many
      types  of "prairie"  and a  particular stabilizer  can  be effective for
      one  of these "prairie" types without serious environmental damage.  In
      other  "prairies," however,  this  same stabilizer would produce irreversible
      effects  and must not be used.   Based upon this  type of comparison with
      each of  the land types, the Mnot acceptable" assignment is made where
      there  is an irretrievable commitment of the natural resources present.
      d,   Not  Applicable  — materials  that cannot be  applied because of soil
      conditions, temperature  extremes, or moisture  conditions.

A.6  APPENDIX A REFERENCE
1.
Ingles, O.G., and J.B. Metcalf.  Soil Stabilization Principles and Practice.
J. Wiley § Sons, New York—Toronto, 1973.  374 pp.
                                      A-7

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A-9