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                                        FIGURE 9-2
                            CONFIGURATION OF STATIC MIXER
                  Air
   Flow
Source: USEPA, 1985
                                           9-18
-------
This concentration is  sufficient  only  for  degradation  of  about  5 mg/1
hydrocarbons, and would therefore  provide  an  inadequate oxygen  supply.   A
pressurized line can increase oxygen concentrations  as can the  use of pure
oxygen.

     The equilibrium oxygen  concentration  in  water  increases  with increased
air pressure according to Henry's  Law  (Sawyer and McCarty,  1967):

where:    CL =  PIL

          CT = concentration of oxygen in  liquid  (mg/1)
           Lt

             = volume  fraction (0.21 for 0 in air)

          P  = air pressure  (atm)

          H,  = Henry's Law Constant for oxygen.

     The value of Henry's Law Constant  is  43.8 mg/1-atmosphere  at 68°F  (20°C).
 Pressure increases with groundwater depth at the rate of 0.0294 atmospheres
per foot.

     The use of in-situ aeration wells  (Figure 9-3)  is a  more suitable  method
for injecting air into contaminated leachate  plumes.   A bank  of aeration wells
can be installed to provide  a zone of  continuous aeration through which the
contaminated groundwater would flow.   Oxygen  saturation conditions can  be
maintained for degrading organics  during the  residence time of  groundwater
flow through the aerated zone.  The required  time for  aeration  can be derived
from bench-scale studies.  Residence time  (t  ) through the  aerated zone can be
calculated from Darcy's equation  (Freeze and  Cherry, 1979) using groundwater
elevations (i.e., head) and  hydraulic  conductivity  as  follows:
          t  = (L )2/K(h1-h2)
           L     cl      •*-  *•*
where:
          t  = residence time (sec)

          K  = hydraulic conductivity (ft/sec)

          L  = length of aerated zone (ft)
           3
          h  = groundwater elevation at beginning of aerated zone  (ft)

          ho = groundwater elevation at end of aerated zone (ft).

     In the design of an in-situ aeration well zone system, the  zone must  be
wide enough to allow the total plume to pass through.  The flow  of air must be
sufficient to give a substantial radius of aeration while small  enough to  not
cause an air barrier to the flow of groundwater-
                                     9-19
-------
                                           Figure 9-3
               POSSIBLE CONFIGURATION OF IN SITU AERATION WELL BANK
      Plane View
                                                                     Zone of Aeration
         Surface Contours.
                                                                        Direction of Groundwater Flow
Cross-sectional
View
A

c
1

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, ••••••
• 0 0
••*:
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Source: USEPA, 1986
                                            9-20
-------
     Various methods can be used to inject air or pure oxygen.  Air has been
sparged into wells using diffusers.  For example, Raymond et al.  (1975),
sparged air into wells using diffusers attached to paint sprayer  type
compressors which could deliver approximately 2.5 cubic feet per  minute.  They
were fitted with steel end plates and fittings to accommodate a polyethylene
air line and a nylon rope and were suspended into the wells.

     A blower can also be used to provide the flow rate and pressure for
aeration.  At the groundwater bioreclamation project in Waldwick, NJ,
5 pounds per square inch pressure is maintained in nine 10-foot aeration
wells, each with an air flow of 5 cubic feet per minute (Groundwater
Decontamination Systems, Inc., 1983).

     Microdispersion of air in water using colloidal gas aprons (CGA) creates
bubbles 25 to 50 micrometers in diameter.  This is a newly developed method
which holds great promise as a means of introducing oxygen to the subsurface
(Michelsen, Wallis, and Sebba, 1984).  With selected surfactants, dispersions
of CGA's can be generated containing 65 percent air by volume.

     Oxygenation systems, either in-line or in-situ can also be installed in
order to supply oxygen to the bioreclamation process.  Their advantage over
conventional aeration is that higher oxygen solubilities and hence, more
efficient oxygen transfer to the microorganisms can be attained.  Solubilities
of oxygen in various liquids are four to five times higher under  pure oxygen
systems than with conventional aeration.  Therefore, in-line injection of pure
oxygen will provide sufficient dissolved oxygen to degrade 20 to  30 mg/1 of
organic material, assuming 50 percent cell conversion.  The higher oxygen
solubilities may provide some flexibility in the design of cell banks,
especially at greater pressures, since the oxygen may not be used up
immediately, as with aeration.

     Hydrogen peroxide (^02) as an oxygen source has been used successfully
at the cleanup of several spill sites (Brubaker, G.R. FMC Aquifer Remediation
Systems, Princeton, NJ, personal communication, 1985).  Advantages of hydrogen
peroxide include:

     •  Greater oxygen concentrations can be delivered to the subsurface.
        100 mg/1 HO  provides 50 mg/1 0 .

     •  Less equipment is required to oxygenate the subsurface.  Hydrogen
        peroxide can be added in-line along with the nutrient solution.
        Aeration wells are not necessary.

     •  Hydrogen peroxide keeps the well free of heavy biogrowth.  Microbial
        growth and subsequent clogging is sometimes a problem in  air injection
        systems (Yaniga, Smith, and Raymond, 1984).

Hydrogen peroxide is cytotoxic, but research has demonstrated that it can be
added to acclimated cultures at up to 1,000 ppm without toxic effects (Texas
Research Institute, 1982).  The remediation at Granger, Indiana,  involved
adding an initial concentration of 100 ppm, and increasing it to  500 ppm over


                                     9-21
-------
the course of the treatment (API, Washington, DC, personal communication,
1985).

     Hydrogen peroxide decomposes to oxygen and water (H-0    0  + HO).  In
the subsurface, hydrogen peroxide decomposition is catalyzed by chemical and
biological factors.  There has been some concern that decomposition could
occur so rapidly that oxygen would bubble out near the site of injection and
no oxygen would be made available to the distal portions of the treatment
zone.  Research has shown that high concentrations of phosphates (10 mg/1) can
stabilize peroxide for prolonged periods of time in the presence of ferric
chloride, an aggressive catalyst (Texas Research Institute, 1982).  However,
there are problems associated with adding such high phosphate concentrations
to the subsurface, such as precipitation.  One company claims to have
developed specially stabilized hydrogen peroxide products for aquifer
remediation-  However, process performance information on these products is
not available.

     Ozone is used for disinfection and chemical oxidation of organics in
water and wastewater treatment.  In commercially available ozone-from-air
generators, ozone is produced at a concentration of one to two percent in air
(Nezgod, W.  PCI Ozone Corporation, West Caldwell, NJ, personal communication,
1983).  In bioreclamation, this ozone-in-air mixture could be contacted with
pumped leachate using in-line injection and static mixing or using a bubble
contact tank.  A dosage of 1 to 3 mg/1 of ozone can be used to attain chemical
oxidation (Nezgod, W.  PCI Ozone Corporation, West Caldwell, NJ, personal
communication, 1983).  However, German research on ozone pretreatment of
contaminated drinking waters indicates that the maximum ozone dosage should
not be greater than 1 mg/1 of ozone per mg/1 total organic carbon; higher
concentrations may cause deleterious effects to microorganisms (Rice, R.G.
Rip G. Rice, Inc., Ashton, MD, personal communication, 1983).  At many sites,
this may limit the use of ozone as a pretreatment method to oxidize refractory
organics, making them more amenable to biological oxidation.

     A petroleum products spill in Karlsruhle, Germany, was cleaned up in-situ
using ozone as an oxygen source for biological degradation (Nagel et al«, 1982
in Lee and Ward, 1984).  The groundwater was pumped out, treated with ozone,
and recirculated.  Approximately one gram of ozone per gram of dissolved
organic carbon was added to the groundwater and was allowed a contact time of
four minutes in the aboveground reactor.  This increased the oxygen content to
9 mg/1 with a residual of 0.1 to 0.2 gram of ozone per cubic meter in the
treated water.
               b.  Nutrients
     Nitrogen and phosphate are the nutrients most frequently  present  in
limiting concentrations in soils.  Other nutrients required  for microbial
metabolism include potassium, magnesium, calcium, sulfur,  sodium, manganese,
iron, and trace metals.  Many of these nutrients may already be present in  the
aquifer in sufficient quantities and need not be supplemented.


                                     9-22
-------
     The optimum nutrient mix can be determined by  laboratory  growth  studies
and from geochemical evaluations of the site.  Caution must  be exercised  in
evaluating microbial needs based on soil  and groundwater  chemical  analysis.
Chemical analysis does not necessarily indicate what  is available  to  the
microorganisms.  In some cases generalizations can  be made,  e.g.,  if  calcium
is present at 200 mg/1 (a very high concentration), it is likely that calcium
supplementation is unnecessary.

     The form of nutrients may or may not  be critical in  terms of  microbial
requirements, depending on the site.  Studies have  shown  that  forms of
nitrogen and phosphate were not critical  for microorganisms  (Jamison, Raymond,
and Hudson, 1976).  However, it has been  recommended  than an ammonia-nitrogen
source is preferable to a nitrate-nitrogen source because ammonia-nitrogen is
more easily assimilated by microorganisms  (FMC, 1985).  Nitrate is also a
pollutant limited to 10 mg/1 in drinking water.

     The site geochemistry may be a critical factor in determining the form of
nutrients, as well as the added concentrations.  For  example,  use  of
diammonium phosphate could result in excessive precipitation (Jamison,
Raymond, and Hudson, 1976) and nutrient solution containing  sodium could  cause
dispersion of the clays, thereby reducing  permeability (Anderson,  D.,  K.W.
Brown, and Associates, Inc., College Station, TX, personal communication,
1985).  Where calcium is high, it is likely to lead to the precipitation  of
added phosphate, rendering it unavailable  to microbial metabolism. If a  site
is likely to encounter problems with precipitation, iron  and manganese
addition may not be desirable. If the total dissolved solids content  in the
water is extremely high, it may be desirable to add as little  extra salts  as
possible.

     The compositions of some basal salts media are given in Tables 9-7 and
9-8.  Only phosphate and nitrogen had to be added to  a site  in Ambler, PA.
Bulk quantities of ammonium sulfate [ (NH^^SO, )], disodium phosphate
(Na-HPO,), and monosodium phosphate (NaH.PO.) were mixed  in  a  2,200 gallon
tanE truck and added to the groundwater In the form of a  30  percent concen-
trate in water which was metered into the  injection wells (Raymond, Jamison,
and Hudson, 1976).  Phosphate concentrations in injection wells varied from
200 to 5,800 mg/1 throughout the site cleanup.  Phosphate concentrations
in all wells were determined weekly and injection rates were adjusted
accordingly.

     CDS, Inc. used the basal salt medium  listed in Table 9-8  in the  combined
surface/in-situ treatment system at the Biocraft site (Jhaveri and Mazzacca,
1984).  The nutrient solution used at the  Granger, Indiana,  site was  composed
of ammonium nitrate and disodium phosphate (FMC, 1985).

     An organic carbon source, such as citrate or glucose, could be added  if
the compound of interest is only degraded  cometabolically and  a primary carbon
source is required.  Such additions could  also be made when  low levels of
contaminants are present and are not sufficient to sustain an  active  microbial
population.  Citrate, or another chelate such as EDTA, could be added to hold
metals in solution if water is alkaline, a condition  under which metals may


                                     9-23
-------
                    TABLE 9-7
        COMPOSITION OF BASAL SALTS MEDIUM

Salt Type
KH2P04
Na2HP04
(NH4)N03
MgS04.7H20
Na,CO,
£• J
CaCl2.2H20
MnS04.H20
FeS04.7H20
Concentration (mg/1)
400
600
10
200
100
10
20
5

Source:  Jamison, Raymond, and Hudson, 1976
                    TABLE 9-8
       BASAL SALT MEDIUM USED BY CDS INC.

Salt
NH,C1
4
KH2P04
K2HP04
MgS04
Na2C03
CaCl2
MnSO,
4
FeSOA
4
Concentration (mg/1)
500

270
410
1.4
9
0.9
1.8

0.45


Groundwater Decontamination Systems, Inc., 1983
                      9-24
-------
precipitate.  Citrate, however, will be preferentially degraded relative to
other organics, and could slow the degradation of contaminants.  Addition
of low concentrations of a source of araino acids, such as peptone or yeast
extract, could promote biodegradation.  However, high concentrations of these
compounds could inhibit degradation of contaminants because of preferential
degradation.
               c.  Design of Delivery and Recovery Systems
     One of the major factors determining success of an in-situ treatment
system is to ensure that the injection and recovery systems are designed to
accomplish the following:

     •  Provide adequate contact between treatment agents and contaminated
        soil or groundwater

     •  Provide hydrologic control of treatment agents and contaminants to
        prevent their migration beyond the treatment area

     •  Provide for complete recovery of spent treatment solutions and/or
        contaminants where necessary.

     A number of design alternatives are available for delivering nutrients
and oxygen to the subsurface and for collecting and containing the ground-
water.  These methods can generally be categorized as gravity flow or forced
methods.  Most of the systems that have been used for bioreclamation have
involved the use of subsurface drains (gravity system), injection wells and
extraction wells.  Subsurface drains and extraction wells are described in
detail in Sections 5.2 and 5.1, respectively.  Some examples of delivery and
recovery systems are described below.

     Figure 9-4 illustrates a hypothetical configuration in which groundwater
is extracted downgradient of the zone of contamination and reinjected
upgradient.  In-situ aeration supplies oxygen directly to the contaminated
plume while nutrients and oxygen are added in-line by way of mixing tanks.
Treated water is infiltrated through contaminated soil in order to flush
contaminants from the soil.  Extraction and injection wells can be used to
treat contaminants to almost any depth in both the saturated and unsaturated
zone.  However their use becomes cost-prohibitive in very low permeability
soils because of the need to space the wells very close together to ensure
complete delivery or recovery.  Subsurface drains can be used under conditions
of moderately low permeability although delivery and recovery of chemicals
will be slow.  They are generally limited to depths of 40 feet or less because
of the cost associated with excavation (shoring, dewatering, hard rock
excavation) of the trench.  Surface gravity delivery systems (e.g., spray
irrigation, flooding, ditches) which involve application of treatment
solutions directly to the surface, as illustrated by "surface flushing" in
Figure 9-4, are most effective for treating shallow contaminated zones located
                                     9-25
-------
                               FIGURE 9-4
    SIMPLIFIED VIEW OF GROUNDWATER  BIORECLAMATION
                                   Subsurface Aeration Wells
Inaction Well
                                                           Extraction Well
                                                    Direction of Flow
       Simplified View of
       Bioreclamation of
       Soil and Groundwater
               Aeration Zone

Direction of Groundwater Flow
                                                                     Extraction Well
                                    9-26
-------
in  the unsaturated  zone.   They  can  also  be  used  to  treat  contaminants in the
saturated zone, provided  the  following conditions are  met:

     •  The soil above  the saturated  zone  (through  which  treatment  solutions
        percolate)  is sufficiently  permeable  to  allow  percolation of  treatment
        solutions to the  groundwater  within a reasonable  length of  time

     •  Groundwater flow  rates  must be sufficient to ensure  complete  mixing of
        the treatment solutions with  the groundwater.

     The feasibility and  effectiveness of these  methods is affected by
topography and climate.

     Figure 9-5 shows the design of a groundwater injection/recovery  system
which is currently  being  used for bioreclamation at an Air Force site.
(SAIC/JRB, 1985).   The  system,  which  is  designed to operate  in moderately low
permeability soils, consists  of nine  pumping  wells  and four  injection wells.
Groundwater is pumped at  an even rate from  the pumping wells to a central flow
equalization (surge tank).  Flow is metered from this  tank into a length of
pipe into which measured  amounts of nutrients and hydrogen peroxide are added.
The treated water then  flows  to a distribution box  to  be  distributed  at an
even rate to each of the  four injection  wells.   Overflow  from the equalization
tank will flow into an  on-site  storage tank.

     The injection/recovery system was designed  using  a two-dimensional,
geohydrologic non-steady  flow model which simulated the flow of groundwater at
the site in response to an injection/recovery pumping  system.

     Important criteria used  for the  design of the  injection/recovery system
include the following:

     •  The groundwater injection rate will be the  same as the rate determined
        during the  field  testing program

     •  All injected groundwater and  associated  elements  are to be  kept within
        the site boundary to  prevent  the transport  of  contaminants  to adjacent
        areas (this implies that there may  be some  net groundwater  pumpage at
        the site)

     •  The distance between  the injection-pumping wells  should be  such that
        approximately six injection-pumping cycles can be completed within a
        6-month period.

     Figure 9-6 illustrates an  injection trench  used in the  treatment of  the
Biocraft site (Jhaveri and Mazzacca,  1983).   The trench was  10 feet deep  by
4 feet wide by 100 feet long.   The trench had a  15 mil plastic liner  installed
on the bottom, back, ends, and  top such  that  reinjected water  only  flowed out
of the front (downgradient) face of the  trench.  About 40 feet of slotted
steel pipe was installed  horizontally in the  trench to carry reinjected water
into the trench system.   As water flowed into the injection  trench, the water
was forced to exit only from  the front face.  Backflow is minimized by this
                                     9-27
-------
FIGURE 9-5. PLAN VIEW OF EXTRACTION/INJECTION SYSTEM
               USED AT AIM AIR FORCE SITE
                                             KEY:
                                                Pumping Wells

                                            j)  Injection Wells
                                            	'   Untreated Groundwater Lines

                                             — ~   Treated Groundwater Lines
                            9-28
-------
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                                                         9-29
-------
design feature.  Barriers can also be used behind the trench and extended  to  a
point where backflow is further minimized.  In extreme cases, total control
over backflow and plume containment can be obtained by installing a
circumferential wall barrier.

     Optimum extraction and injection flow rates will many times be pre-
determined by aquifer yield limits or hydraulic design for plume containment.
The factors affecting aquifer flow rates are described in Section 5.1.

     Aquifer flow rates should be sufficiently high so that the aquifer is
flushed several times over the period of operation.  Thus, if the cleanup
occurs over a three year period, flow rates between injection and extraction
wells should be such that a residence time of one-half year dr less occurs
between the well pairs.  This corresponds to six or more flushes.  Several
recycles would cause flushing of soils containing organics, preventing the
clogging caused by microorganism buildup because of increased flow rate; more
even distribution of nutrients and organic concentration within the plume; and
better and more controlled degradation.  Flow rates and recycle should not be
high enough to cause excessive pumping costs, loss of hydraulic containment
efficiency because of turbulent conditions, corrosion, excessive manganese
deposition, flooding, or well blow out.  The operating period will depend  on
the biodegradation rate of the contaminants in the plume and the amount of
recycle.  If the period of operation is excessively long, for example more
than five years, the operating costs of bioreclamation may outweigh the
capital costs of another remedial alternative.


          9.1.3.2  Anaerobic Bioreclamation
     Anaerobic treatment is generally not as promising for site remediation  as
aerobic treatment.  Anaerobic processes are slower, fewer compounds can  be
degraded, and the logistics of rendering a site anaerobic have not been
developed to date.

     Anaerobic metabolism includes:  (1) anaerobic respiration, in which
nitrate or sulfate may be used by nitrate or sulfate reducers as a terminal
electron acceptor, and (2) interactive fermentative/methanogenic processes,
which are carried out by what is referred to as a methanogenic consortium.

     If it were possible to provide proper reducing conditions, degradation  by
methanogenic processes would be promising.  A considerable body of research
indicates that methanogenic consortiums are active in the subsurface  and are
capable of degrading certain organics (Ehrlich et al., 1982; Parsons  et  al.,
1982; and Suflita and Gibson, 1984).  Most notably, methanogenic consortiums
are able to degrade TCE, PCE, and other lower molecular weight halogenated
organics which generally cannot be degraded by aerobic or other respiratory
processes. Reductive dehalogenation appears to be the primary mechanism
involved in degradation.  Methanogenic consortiums are also able to degrade
various aromatics, halogenated aromatics, and some pesticides.  Degradation  of
                                      9-30
-------
petroleum hydrocarbons, straight-chain and branched alkanes  and  alkenes,  is
not possible under methanogenic conditions.

     Methanogenic_activity requires a very low  redox  potential,  -250  mv  or
less.  No 0«, NO. , or SO,   can be present or  the redox potential will  not  be
low enough.  Currently, there are no demonstrated methods  for  rendering  a site
anaerobic.  When the contamination is shallow,  there  is an aquitard below the
zone of contamination, and the flow of groundwater can be  contained,  it  might
be possible to induce reducing conditions by  flooding the  site,  as one would a
rice paddy.  Another possible method or rendering the site anaerobic  would be
to add excessive amounts of easily biodegradable organics  so that the oxygen
would be depleted.  One other promising possibility might  be to  circulate
groundwater to the surface through anaerobic  digesters or  anaerobic lagoons.
These methods may require long retention times  because of  slow degradation
rates under anaerobic conditions.  There have been no reports  of pilot or
field studies using anaerobic degradation under methanogenic conditions.

     Nitrate respiration may be a feasible approach to decontaminating an
aquifer.  Denitrification (the reduction of NO  to NH or  N  )  has been
demonstrated to occur in contaminated aquifers.  Nitrate respiration  was  used
successfully in the treatment of an aquifer contaminated with  aromatic and
aliphatic hydrocarbons (see Table 9-4) (Stief,  1984).  Nitrate can be added
in-line along with other nutrients and intimate mixing with  groundwater  can
occur.  The cost is moderate; all that is required is the  nutrient feed  system
and an in-line mixer.

     Nitrate, however, is a pollutant, limited  to 10  ppm in  drinking  water.
Consequently, it may be more difficult to obtain permits for use of nitrate  at
a site than for oxygen or hydrogen peroxide.  Additionally,  degradation  rates
under aerobic conditions are more rapid and a broader range  of compounds  can
be degraded.  There is no reason why nitrate  respiration would be a better
treatment approach given the amount of success  that has been demonstrated with
aerobic treatment approaches to date.


     9.1.4  Operation and Maintenance


     Operation and maintenance of a bioreclamation process involve aspects of
the hydraulic system as well as the biological  system.  The  hydraulic aspects
relate to pumps, extraction and injection wells, and  injection trenches;  these
are discussed in Sections 5.1 and 5.2.

     Monitoring a number of parameters is necessary to determine process
performance.  Monitoring of groundwater can be  performed at  the  injection and
extraction wells, as well as at monitoring wells.  Monitoring  wells should be
placed on-site to monitor process performance and off-site to  monitor for
pollutant migration as well as to provide background  information on changes  in
subsurface conditions due to seasonal fluctuation.  Table  9-9  lists parameters
which should be monitored, and suggests methods which can  be used to  monitor
these parameters.


                                     9-31
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                                  TABLE 9-9.
                       RECOMMENDED PARAMETERS TO MONITOR
Parameter
Location     Media
of Analysis
                    Analytical Method
Total Organic
Carbon (TOC)

Priority pollutant
analysis or analysis
of specific organics

Microbiology-
cell enumerations
laboratory   groundwater
laboratory
laboratory
                      field
Temperature
conductivity
dissolved oxygen (DO)
PH
Alkalinity
Acidity, M&P
Chloride
Hardness (total
NH--N
NO^-N
PO,, all forms
SOT
TDS (total dissolved
     solids)

Heavy metals
(if present)
field
soil and
groundwater
soil and
groundwater
             groundwater
groundwater
field
groundwater
field
laboratory
groundwater
soil and
groundwater
                    TOC analyzer
Direct counts.  Plate
counts on groundwater
media or enriched
media.

Plate counts with
portable water test
kits (e.g. Soil Test
Inc., Evanston, IL).

In-situ water quality
monitoring instrument
or prepackaged
chemicals, field test
kits.

Prepackaged chemicals/
field test kits; water
analyzer photometer
(Soil Test. Inc.,
Evanston, IL; Lamotte
Chemical, Chestertown,
MD).
Prepackaged chemicals/
test kits;
                                                       GC/MS; AAS.
                                                                  (2)
                                                                   (continued)
                                     9-32
-------
                            TABLE 9-9.   (continued)
Parameter             Location     Media               Analytical Method
                      of Analysis
Hydrogen peroxide     field        groundwater         Prepackaged chemicals
    2)                                                 for ^2°2' test  striPs
                                                       available.  Titanium
                                                       sulfate titration  and
                                                       spectrophotometer
                                                       analysis for H^C^  for
                                                       greater accuracy.


   GC/MS = gas chromatography/mess spectrometry
(2)
v 'AAS = Atomic absorption spectrometry
     In a biological system, pH should be maintained in a range between 6 and
8 and concentrations of both nutrients and organics should be kept as uniform
as possible to protect against shock loading.  Dissolved oxygen should be
maintained above the critical concentration for the promotion of aerobic
activity, which ranges from 0.2 to 2.0 mg/1, with the most common being
0.5 mg/1 (Hammer, 1975).

     Clogging of the aquifer, injection wells or trenches, or extraction wells
by microbiological sludge is a possibility.  CDS Inc. installed two wells in
each of their injection trenches in case flushing was ever required to remove
sludge.  After 1-1/2 years of operation, clogging had not occurred (Ground-
water Decontamination Systems Inc., 1983).  However, problems with biofouling
and plugging of sparging points was encountered during a spill cleanup con-
ducted by Groundwater Technology (Yaniga, Smith, and Raymond, 1984).  This
interfered with oxygen transfer and necessitated frequent mechanical cleaning.
When hydrogen peroxide was substituted for air sparging in order to deliver
increased quantities of oxygen to the aquifer, one added benefit was that the
hydrogen peroxide kept the wells free of heavy biogrowth.

     The permeability of the aquifer could be reduced due to precipitation, as
discussed in Section 9.2.2.  Other factors, such as dispersion of clays, could
reduce aquifer permeability.  When calcium concentrations are high in the
soil, phosphates can be rapidly attenuated due to precipitation with calcium,
becoming unavailable for microbial metabolism.  Nutrient formulations should
be devised with the help of experienced geochemists which will minimize
problems with precipitation and dispersion of clays.  One company claims to
                                     9-33
-------
have developed special soil preconditioners and nutrient formulations which
reduce these problems and maximize nutrient mobility and solubility; however,
no process performance data are available on these products.

     Maintenance of the bacterial population at their optimal levels is also
important, especially for selective mutant organisms which tend to be more
sensitive than naturally occurring species.  A continuous incubation facility
operating at higher temperatures and under more controlled conditions could be
used to maintain the microbial population.  The high biomass-containing stream
formed from such a facility could then be reinjected via wells or trenches so
as to reinoculate the subsurface continuously with microorganisms.

     Aeration wells may be particularly susceptible to operational problems.
If injected gas fluidizes the material around it, soil substrata shifts can
occur which may cause a well blowout (free passage of air to the surface).
The cone of influence in a blown out well will be greatly reduced, therefore
requiring the installation of a new well.  The best method to prevent blowouts
is to keep gas velocities below those necessary to cause fluidization, or to
place wells deep enough so that overburden pressure prevents excessive fluidi-
zation, or both (Sullivan, Chemineer Kinecs, Dayton, OH, personal communica-
tion, 1983).  Suntech stated that a number of aeration wells became inopera-
tive because of blowout during their groundwater cleanup in 1972 and had to be
replaced (Raymond, Jamison, and Hudson, 1976).  This suggests that aeration
well blowout could become a commonly encountered problem if attention is not
paid to the design criteria.


     9.1.5  Technology Selection/Evaluation


     Aerobic bioreclamation has been demonstrated to be effective in degrading
organics at more than 30 spill sites.  Although it has not yet been demon-
strated at hazardous waste sites, it can be expected to be effective and
reliable provided the organics are amenable to aerobic degradation and the
hydraulic conductivity of the aquifer is sufficiently high.  There are sub-
stantial research data to suggest that microorganisms found at uncontrolled
hazardous waste sites are well-acclimated to the wastes.  Effectiveness and
reliability could be adversely affected by factors, such as precipitation,
which could reduce the permeability of an aquifer.

     Relative to conventional pump and treat methods, bioreclamation may be
more effective since it is capable of degrading organics sorbed to soils.
Sorbed organics are not removed using conventional pump and treat methods.

     The nature of the delivery systems can effect the reliability of the
bioreclamation approach.  Pumping systems are prone to mechanical and
electrical failure.  However, repairs can be made relatively quickly.
Subsurface drains are less prone to failure since there are no electrical
components.  Where mechanical failures do occur, repairs can be both costly
and time consuming.
                                     9-34
-------
     Implementation of a remedial action involving bioreclamation will  take
longer than excavation and removal of contaminated soils.  Depending upon  the
site, it could also take longer than a conventional pump and  treat  approach.
The advantage of in-situ bioreclamation over a pump and treat  approach  is  that
in-situ biodegradation treats contaminated subsurface soils,  thereby removing
the source of groundwater contamination.

     The increased time required for in-situ bioreclamation is  dependent
primarily upon the degradation rates, which are in turn dependent upon  oxygen
availability.  The form in which oxygen is delivered to the subsurface  and the
aquifer permeability are the critical factors in this respect.  As  discussed
previously, far more oxygen can be delivered to the subsurface  in the form of
hydrogen peroxide•

     Other aspects of implementation are similar to implementation  of conven-
tional pumping or subsurface drain systems with a few exceptions.   Depending
upon the hydraulic conductivity, drains or wells must generally be  spaced
closer together to ensure nutrient and oxygen availability at all portions of
the zone being treated.  The lower the flow rate of the nutrient/oxygen-
enriched water and the more rapidly nutrients and oxygen are  attenuated, the
closer the injection wells or drains must be spaced.  Well/drain spacing will
also be dictated by the need, if any, to contain the contaminated plume or
treatment solution.

     There are few additional safety hazards associated with  in-situ
bioreclamation aside from those hazards normally associated with being  on  a
hazardous waste site or a drill site.  Since wastes are treated in  the  ground,
the danger of exposure to contaminants is minimal during a bioreclamation
operation relative to excavation and removal.

     A nutrient/oxygen or nutrient/hydrogen peroxide solution does  not
represent an environmental threat.  Most of the nutrients will  be utilized and
attenuated by microbial activity.  If the form of the nutrient  is carefully
selected (e.g. ammonia-nitrogen rather than nitrate-nitrogen),  the  remaining
nutrients will not present an environmental threat.  The hydrogen peroxide
will rapidly decompose in the subsurface to oxygen and water.

     The only treatment reagent which could pose a hazard, if used,  is  the
concentrated hydrogen peroxide solution prior to mixing with groundwater.
Worker protection for operations involving hydrogen peroxide outside of a
closed container or pipe should include the use of chemically resistant
gloves, an apron, and a face shield.  Safety training in the use of  hydrogen
peroxide should be provided by qualified personnel.


     9.1.6  Costs
     Costs for biological in-situ treatment are determined by the nature of
the site geology and geohydrology, the extent of contamination, the kinds
and concentrations of contaminants, and the amount of groundwater and soil


                                     9-35
-------
requiring treatment.  There is no easy formula for predicting costs.  Costs
provided for actual site cleanups indicate that biological treatment can be
far more economical as an alternative to, or in conjunction with, excavation
and removal or conventional pump and treat methods.

     In-situ treatment costs include costs for well construction and pumping.
These are provided in Sections 5.1 and 5.2.  Unit costs for chemicals,
nutrients, and hydrogen peroxide are provided in Table 9-10.  Cost data for an
actual and hypothetical site cleanups involving in-situ treatment are
presented below.

     Total capital and research and development costs for cleanup of the
Biocraft site (Table 9-11) were $926,158 including $446,280 which were spent
on process development (R&D).  Project costs also included the hydrogeological
study, and design and operation of the groundwater injection and collection
system, and biostimulation plant.  Total operating costs, based on treating
13,680 gallons/ day, were approximately $226/day, or $0.0165/gal.  The total
cost including amortization based on projected costs is $0.0358/gal over a
three year period. Prior to the biological treatment program, contaminated
water had been removed at a rate of 10,000 gal/month.  The average disposal
cost had been $0.35/gal (Jhaveri and Mazzacca, 1984).  The cost of biological
treatment of an equal number of gallons is an order of magnitude less than
that for disposal.  The Biocraft site employed surface biological reactors as
well as enhancing in-situ treatment by reinfiltrating oxygen and nutrient
treated groundwater.  Costs for in-situ treatment alone would have been less
because process plant design and equipment would not be included in an in-situ
approach.  (See Table 9-11).

     Table 9-12 presents the estimated site cleanup costs for hypothetical
sites involving the use of hydrogen peroxide as an oxygen source for the
enhancement of in-situ biodegradation (FMC, 1985).  The cleanup of 300 gallons
of gasoline from a sand gravel aquifer over a period of 6 to 9 months is
between $70,000 and $120,000 (Site A).  Cleanup of 3,000 gallons of diesel
fuel from a fractured bedrock formation is estimated to require 9 to 12 months
and $160,000 to $250,000.  The cost estimate for degrading 10,000 gallons of
jet fuel from a fine gravel formation is estimated to cost $400,000 to
$600,000 and take 14 to 18 months.
9.2  Chemical Treatment
     9.2.1  General Description
     Generally, organic and inorganic contaminants can be immobilized,
mobilized for extraction, or detoxified.  Technologies placed in the category
"immobilization" include precipitation, chelation, and polymerization.  The
category encompassing methods for mobilizing contaminants for extraction  is
termed "soil flushing."  Flushing agents include surfactants, dilute acids and
                                     9-36
-------
                                  TABLE 9-10.
                                CHEMICAL COSTS
Category
Chemical
Cost/Unit
Acids
Hydrochloric acid, 20° Baume tanks
Nitric acid 36°to 42° Baume tanks
Sulfuric acid
  virgin, 100%
  smelter, 100%
$55-105/ton
$195/ton

$61-95.9/ton
$48-65/ton
Bases

Chelating agents


Fertilizers
(Microbial nutrients)
Caustic soda, liquid 50%, low iron  $255-285/ton
Liming material



Oxidizing agents


Reducing agents

Precipitating agents
Ammonium chloride
Citric acid

Ammonia, anhydrous, fertilizer
Ammonium chloride
Ammonium sulfate
Sodium monophosphate
Sodium diphosphate
Phosphoric acid
  75%, commercial grade
  52-54% a.p.a., agricultural
    grade
Potassium muriate, 60 to 62%,
  minimum
Potassium chloride
Potassium-magnesium sulfate

Agricultural limestone (dolomite)
Lime
Hydrated lime

Hydrogen peroxide, 35%
Potassium permanganate
$18/100lbs
$0.81-$1.19/lb

$140-$215/ton
$18/100 Ibs
$73-79/ton
$55.75/100 Ibs
$54.50/100 Ibs

$27.5/100 Ibs

$3.10/unit-tona

$0.82-0.92/unit-ton
$105/ton
$59/ton

3.50-34/tonb
$30.75-45/ton
$32.5-34.5/ton

$0.24/lb
$1.03-1.06/lb
Caustic soda, liquid 50%, low iron  $255-285/ton
Ferrous sulfate
  heptahydrate
  monohydrate
                                                           130/ton
                                                           160/ton
                                                                   (continued)
                                     9-37
-------
                            TABLE 9-10. (continued)
Category               Chemical                            Cost/Unit
Surfactant                                                             c
  Anionic              Witconate 605A                      0.65-0.85/lbc
                       Witconate P-1020BV                  0.70-0.88/lb
                       (calcium sulfonates)                           c
  Nonionic             Adsee 799                           0.75-0.87/b
Source:  Schnell, 1985, unless otherwise noted.

a.  unit-ton:  1 percent of 2,000 pounds of the basic constituent or other
    standard of the material.  The percentage figure of the basic constituent
    multiplied by the unit-ton price gives the price of 2,000 pounds of the
    material.
b.  Source:  USEPA, 1984a.
c.  Source:  Witco Chemical Corp., Houston, TX, personal communication, 1985:
    cost varies depending on quantity purchased (drum, truckload, or bulk).


bases, and water.  Detoxification techniques include oxidation, reduction,
neutralization, and hydrolysis.

     These categories do not define the limits of each technology.  For
example, a treatment method that immobilizes a contaminant may also serve to
detoxify it; a flushing solution that mobilizes one contaminant may
precipitate, detoxify, or increase the toxicity of another.

     Tables 9-13 and 9-14 provide a summary of those in-situ chemical
treatment methods for organics and inorganics, respectively, that are most
promising or have been most widely discussed in the literature.  The compounds
amenable to treatment, the treatment reagents, and the process are summarized.


     9.2.2  Applications/Limitations
     The feasibility of an in-situ treatment approach  is dictated  by  site
geology and hydrology, soil characteristics, and waste characteristics.  Since
the application of many chemical in-situ treatment techniques  to hazardous
waste disposal site reclamation is conceptual or in the developmental stage,
there is little hard data available on the specific site characteristics
that may limit the applicability of each method.  A list of  site and  soil
                                      9-38
-------
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-------
                                  TABLE 9-12.
               ESTIMATED COSTS FOR HYPOTHETICAL BIORECLAMATIONS
                  USING HYDROGEN PEROXIDE AS AN OXYGEN SOURCE
                   Site A
Site B
Site C
Contaminant
Formation
Flow Rate
Project Time
Estimated Costs
300 gallons
gasoline
Sand/gravel
50 gpm
6-9 months
$70-120M(1)
2,000 gallons
diesel fuel
Fractured bed rock
10 gpm
18-24 months
$200-300M(1)
10,000 gallons
jet fuel
Coarse gravel
100 gpm
18-24 months
$500-700M(1^

(1)M=1000
Source: FMC, 1985






characteristics considered important in evaluating the treatment  applicability
is provided in Table 9-15 (Sims and Wagner, 1983).

     Most of the treatment approaches discussed in this section involve  the
delivery of a fluid to the subsurface.  Therefore, the same factors that  limit
the use of injection/extraction wells, drains, or surface gravity application
systems such as flooding and spray irrigation for bioreclamation  will  limit
the applicability of most in-situ chemical treatment approaches.   Minimal
permeability requirements must be met if the treatment solution is to  be
delivered successfully to the contaminated zone.  Sandy soils  are far  more
amenable to in-situ treatment than clayey soils.  Further, the contaminated
groundwater must be contained within the treatment zone.  Measures must  be
taken to ensure that treatment reagents do not migrate and, of themselves,
become contaminants.  Care must be taken during the extraction process not to
increase the burden of contaminated water by drawing uncontaminated water  into
the treatment zone from the aquifer or from hydraulically connected surface
waters.

     Potential chemical reactions of the treatment reagents with  the  soils and
wastes must be considered.  Most hazardous waste  disposal sites contain  a mix
of contaminants.  A treatment approach that may neutralize one contaminant may
render another more toxic or mobile; for example, chemical oxidation  will
                                      9-40
-------























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-------
                                  TABLE 9-15.
  SITE AND SOIL CHARACTERISTICS IDENTIFIED AS IMPORTANT IN IN-SITU TREATMENT
Characteristics


Site location/topography

Slope of site-degree and aspect

Soil, type and extent

Soil profile properties
   depth
   boundary characteristics
   texture*
   amount and type of coarse fragments
   structure*
   color
   degree of mottling
   presence of carbonates
   bulk density*
   cation exchange capacity*
   clay content
   type of clay
   pH*
   Eh*
   surface area*
   organic matter content*
   nutrient status*
   microbial activity*

Hydraulic properties and conditions
   depth to impermeable layer or bedrock
   depth to groundwater*, including seasonal variations
   infiltration rates*
   permeability* (under saturated and a range of unsaturated  conditions)
   water holding capacity*
   soil water characteristic curve
   field capacity/permanent wilting point
   flooding frequency
   run-off potential*
   aeration status*

                                                                    (continued)
                                     9-44
-------
                           TABLE 9-15.  (continued)
Characteristics
Clitnatological factors
   temperature*
   wind velocity and direction
*  Factors that may be managed to enhance soil treatment

Source:  Sims and Wagner, 1983

(Manuscripts originally printed in the Proceedings of the National Conference
on Management of Uncontrolled Hazardous Waste Sites.  1983.  Available  from
Hazardous Materials Control Research Institute, 9300 Columbia Blvd., Silver
Spring, MD  20910).


destroy or reduce the toxicity of many toxic organics, but chromium III,  if
present, will oxidize to the more toxic and mobile chromium VI state.   The
permeability of soils may be reduced by the treatment approach.  In soils high
in iron and manganese, for example, oxidizing the subsurface could result in
the precipitation of iron and manganese oxides and hydroxides, which could
clog the delivery system and the aquifer.


     9.2.3  Soil Flushing


     Organic and inorganic contaminants can be washed from contaminated soils
by means of an extraction process termed "soil flushing," "solvent flushing,"
"ground leaching," or "solution mining."  Water or an aqueous solution  is
injected into the area of contamination, and the contaminated elutriate is
pumped to the surface for removal, recirculation, or on-site treatment  and
reinjection.   During elutriation,  sorbed contaminants are mobilized into
solution by reason of solubility,  formation of an emulsion, or by chemical
reaction with the flushing solution.

     Solutions with the greatest potential for use in soil flushing fall into
the following classes:

     •  Water

     •  Acids-bases

     •  Complexing and chelating agents
                                     9-45
-------
     •  Surfactants

     •  Certain reducing agents.

     Water can be used to flush water-soluble or water-mobile organics and
inorganics.  Hydrophilic organics are readily solubilized in water.  Organics
amenable to water flushing can be identified according to their soil/water
partition coefficient, or estimated using the octanol/water coefficient.
Octanol-water partition coefficients are available for a large number of
compounds in:  Substituent Constants for Correlation Analysis in Chemistry and
Biology (Hansch and Leo, 1979).Chemical Property Estimation Methods (Lyinan,
Reehl and Rosenblatt, 1982) provides various methods for estimating the
octanol-water partition coefficient using readily available physical and
chemical data.  Organics considered soluble in the environmental sense are
ones with a partition coefficient (K) of approximately less than 1000 (log K =
3).  High solubility organics, such as lower molecular weight alcohols,
phenols, and carboxylic acids, and other organics with a coefficient less than
10 (log K _
-------
     Another possibility for mobilizing metals which are strongly adsorbed to
manganese and iron oxides in soils is to reduce the metal oxides which results
in release of the heavy metal into solution.  Chelating agents or acids can
then be used to keep the metals in solution.  Treatment agents which may be
suitable for this purpose include hydroxylamine together with an acid, or
sodium dithionite/citrate.

     Surfactants can be used to improve the solvent property of the recharge
water, emulsify nonsoluble organics, and enhance the removal of hydrophobic
organics sorbed onto soil particles.  Surfactants improve the effectiveness of
contaminant removal by improving both the detergency of aqueous solutions and
the efficiency by which organics may be transported by aqueous solutions
(USEPA, 1985).  Surfactant washing is among the most promising of the in-situ
chemical treatment methods.

     Numerous environmentally safe and relatively inexpensive surfactants are
commercially available.  Use of surfactants to date has been restricted to
laboratory research.  Most of the research has been performed by the petroleum
industry for tertiary oil recovery (Barakat et al., 1983; Cash et al., 1977;
Doe, Wade, and Schechter, 1977; and Wilson and Brandner, 1977).  Aqueous
surfactants have also been proposed for gasoline cleanup.  In a study
performed by the Texas Research Institute (1979) for the American Petroleum
Institute, a mixture of an anionic and nonionic surfactants result in con-
taminant recovery of up to 40 percent.  In a laboratory study conducted by
Ellis and Payne (1983), crude oil recovery was increased from less than
1 percent to 86 percent, and PCB recovery was increased from less than
1 percent to 68 percent when soil columns were flushed with an aqueous
surfactant solution.

     Characteristics of surfactants and their environmental and chemical
properties are listed in Table 9-16 (USEPA, 1985).  This table can be used to
aid in the preliminary selection of a surfactant.  However, laboratory testing
of the surfactant should be performed to verify surfactant properties.

     An economically feasible soil flushing method may involve the recycling
of elutriate through the contaminated material, with make-up solvent being
added to the system while a fraction of the elutriate stream is routed to a
portable wastewater treatment system.  The appropriate types of wastewater
treatment operations will depend on waste stream characteristics, and a
discussion of their applications can be found in Section 10.1.

     The advantages of the soil flushing process are that, if the waste is
amenable to this technique and distribution, collection, and treatment costs
are relatively low, solution mining can present an economical alternative to
the excavation and treatment of the wastes.
                                     9-47
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-------
     9.2.4  Immobilization
     Immobilization methods are designed to render contaminants insoluble and
prevent leaching of the contaminants from the soil matrix and their movement
from the area of contamination.  Little is currently known about the
effectiveness and reliability of immobilization techniques (Truett, Holberger,
and Banning, 1982).

     Immobilization methods which are currently being investigated include:
precipitation, chelation, and polymerization.

     Precipitation is the most promising method for immobilizing dissolved
metals such as lead, cadmium, zinc, and iron.  Some forms of arsenic,
chromium, mercury, and some organic fatty acids can also be treated by
precipitation (Huibregtse and Kastman, 1979).  All of the divalent metal
cations can be precipitated using sulfide, phosphate, hydroxide, or carbonate.
However, the solubility product and the stability of the metal complexes vary.
Because of the low solubility product of sulfides and the stability of the
metal sulfide over a broad pH range, sulfide precipitation looks most promis-
ing.  The remaining anions decrease in effectiveness in the following order:
phosphate > hydroxide > carbonate.  Metal carbonates and hydroxides are stable
only over a narrow pH range and the optimum pH range varies for different
metals.  Precipitation of the metal as the metal phosphate may require very
high concentration of orthophosphate since calcium and other naturally
occurring soil cations present in high concentrations will precipitate first.

     Sodium sulfate used in conjunction with sodium hydroxide has  shown wide-
spread applicability for precipitatiion of metals.  Precipitation  takes place
at a neutral or slightly alkaline pH.  Resolubilization of sulfides is low.
Addition of sodium hydroxide minimizes the formation of hydrogen sulfide gas
by assuring an alkaline pH.  Experiments with sulfide precipitation of zinc
indicate that a high residual of unreacted sulfide may remain in solution.

     As with other in-situ 'techniques, precipitation is most applicable to
sites with sand or coarse silt strata.  Disadvantages include the  injection of
a potential groundwater pollutant; the potential for formation of  toxic gases
(in the case of sulfide treatment); the potential for clogging soil pore
space; and the possibility of precipitate resolubilization.

     The use of chelating agents may also be a very effective means of
immobilizing metals although considerable research is needed in this area.
Depending upon the specific chelating agent, stable metal chelates may be
highly mobile (as described in Section 9.2.3) or may be strongly sorbed to the
soil.  Tetran is an example of a chelating agent which is strongly sorbed to
clay in soils (USEPA, 1984a).

     A third method for immobilizing metals applies specifically to chromium
and selenium.  These metals can be present in the highly mobile, hexavalent
state but can be reduced to less mobile Cr (III) and Se (IV) by addition of
ferrous sulfate.  Arsenic exists in soils as either arsenate, As (V), or as
                                     9-50
-------
arsenite, As  (ill),  the more  toxic and  soluble  form.  Arsenic  can  be  effec-
tively immobilized by oxidizing As (ill)  to As  (IV) and  treating the  As  (IV)
with  ferrous  sulfate to form  highly  insoluble Fe-AsO,.

     Polymerization  involves  injection  of a catalyst  into  a  groundwater  plume
to cause polymerization of an organic monomer (e.g.,  styrene,  vinyl chloride,
isoprene, methyl methacrylate, and acrylonitrile).  The  polymerization
reaction transforms  the once  fluid substance into a gel-like,  non-mobile mass.
In-situ polymerization is a technique most suited for groundwater  cleanup
following land  spills or underground leaks of pure monomer.  Applications  for
uncontrolled  hazardous waste  sites are  very limited.  Major  disadvantages
include very  limited application and difficulty of initiating  sufficient
contact of  the  catalyst with  the dispersed monomer (Huibregtse and Kastman,
1979).  In-situ  polymerization was successfully performed  to remedy an
acrylate monomer leak, in which 4,200 gallons of acrylate  monomer  leaked from
a corroded  underground pipeline into a  glacial  sand and  gravel layer.  Soil
borings indicated  that as much as 90 percent of the monomer  had been
polymerized by  injection of a catalyst, activator, and wetting agent
(Williams,  1982).

      In-situ  treatment of a leachate plume using precipitation or  polymer-
ization techniques probably has limited application.  Problems associated with
these techniques include:

     •  Need  for numerous, closely-spaced injection wells  even in  coarse-
        grained  deposits because the action of  precipitation or polymerization
        will  lower hydraulic  conductivities near injection wells reducing
        treatment  effectiveness

     •  Contaminants are not  removed from the aquifer or some  chemical
        reactions  can be reversed allowing contaminants  to again migrate with
        groundwater  flow

     •  Injection  of a potential groundwater pollutant or  the  formation of
        toxic byproducts.

Therefore, prior to the application of  an in-situ precipitation or polymeriza-
tion technique at  a hazardous waste site, thorough laboratory- and pilot-scale
testing should be  conducted to determine deleterious effects and assure
complete precipitation or polymerization of the chemical compounds.

     Solidification methods used for chemical soil consolidation can also
immobilize contaminants.   Solidification and stabilization techniques are
assessed in terms of their applicability for in-situ treatment of  landfilled
wastes in Guide to the Disposal of Chemically Stabilized and Solidified Wastes
(USEPA,  1982).  The assessment concluded that most work with these techniques
has not involved in-situ treatment;  most are not applicable to hazardous waste
sites, and most of the techniques involve a thorough mixing of the solidifying
agent and the waste (Truett,  Holberger, and Banning,  1982).  Injection of
silicate gel may be feasible   to immobilize subsurface contaminants, but may
negatively impact groundwater quality (Truett,  Holberger,  and  Sanning, 1982).
                                     9-51
-------
     9.2.5  Detoxification
     In-situ treatment techniques discussed in this section are those which
serve to destroy, degrade, or otherwise reduce the toxicity of contaminants
and include neutralization, hydrolysis, oxidation/reduction, enzymatic
degradation, and permeable treatment beds.  These methods are applicable to
specific chemical contaminants, therefore, use of these in-situ techniques at
waste sites will be limited.

     Neutralization involves injecting dilute acids or bases into the ground-
water to adjust the pH.  This pH adjustment can serve as pretreatment prior to
in-situ biodegradation, oxidation, or reduction to optimize the pH range.  It
can be used to neutralize acidic or basic plumes that need no other treatment,
or to neutralize groundwater following another treatment.  It can also be used
during oxidation, reduction, or precipitation to prevent the formation of
toxic gases including hydrogen sulfide and hydrogen cyanide.

     The pH adjustment can also be used to increase the hydrolysis rate of
certain organics.  Hydrolysis involves the displacement of a group on an
organic moiety with a hydroxyl group from water, according to the displacement
reaction:

                  RX + H20 -» ROH + HX

in which R is the organic moiety and X is the leaving group.  Of the param-
eters which affect the rate of hydrolysis (temperature, solvent composition,
catalysis, and pH), pH adjustment has the greatest potential.  The rate of
hydrolysis can be increased up to one order of magnitude for a change of one
standard unit in pH (USEPA, 1985).  Classes of compounds with potential for
in-situ degradation by hydrolysis include:

     •  Esters

     •  Amides

     •  Carbamates

     •  Phosphoric and phosphonic acid esters

     •  Pesticides.

Because a hydrolysis product may be more toxic than the present compound, the
pathways for reactions must be determined to ensure toxic products are not
produced.  USEPA (1985) has a more thorough discussion of this technology.

     Many of the environmental, health, and safety considerations that apply
to solution mining also apply here.  In contrast to solution mining, in-situ
neutralization/detoxification techniques do not inherently incorporate
collection systems.  However, a collection system should be incorporated as a
fail safe measure, to prevent migration of the treatment reagents and any
contaminants which are not successfully treated.
                                     9-52
-------
     Oxidation and reduction reactions serve to alter the oxidation state of a
compound through loss or gain of electrons, respectively.  Such reactions can
detoxify, precipitate, or solubilize metals, and decompose, detoxify, or
solubilize organics.  Oxidation may render organics more amenable to bio-
logical degradation.  As with many of these chemical treatment technologies,
oxidation/reduction techniques are standard wastewater treatment approaches,
but their application as in-situ treatment technologies is largely conceptual.

     Oxidation of inorganics in soils, is for all practical purposes limited
to oxidation of arsenic and possibly some lead compounds.  The in-situ
oxidation of arsenic compounds with potassium permanganate (KMnO,) has been
used to successfully reduce the arsenic concentrations in groundwater in the
vicinity of a zinc ore smelter near Cologne, Germany (Stief,  1984).  64,000
lb- of KMnO, were injected into 17 wells and piezometer wells resulting in an
average decrease in arsenic groundwater concentrations from 13.6 mg/1 to 0.06
mg/1 from 1975 to 1977.  In 1979, however, an increase indicated that the
mixing of groundwater and KMnO, had not been thorough.

     Of the numerous oxidizing agents available, three have been considered
potentially useful in the in-situ detoxification of organics groundwater and
soils contaminated with organics:  hydrogen peroxide, ozone, and hypochlorites
(USEPA, 1985).  Each can react with a broad range of organics and could
potentially oxidize a number of different organic contaminants in a hazardous
waste site-  Selection of the appropriate oxidizing agent is dependent in part
upon the substance or substances to be detoxified, but also upon the feasi-
bility of delivery and environmental safety.  Although there are some
compounds that will not react with hydrogen peroxide but will react with ozone
or hypochlorite, hydrogen peroxide appears to be the most feasible for in-situ
treatment.

     Ozone gas is a very strong oxdizing agent that is very unstable and
extremely reactive.  It cannot be shipped or stored; therefore it must be
generated on-site prior to application.  Ozone rapidly decomposes and its
half-life in groundwater is only 18 minutes (USEPA, 1985).  Ozone is used in
the treatment of drinking water, municipal wastewater, and industrial waste,
but has never been used in the treatment of contaminated soils or groundwater.
Ozone oxidation with ultraviolet irradiation successfully reduced concentra-
tions of benzene, phenols, and trichloroethylene in lake water (Glaze et al.,
1980).

     Hypochlorite, generally available as potassium, calcium, or sodium hypo-
chlorite (bleach) is also used in the treatment of drinking water, municipal
wastewater, and industrial waste.  Hypochlorites have never been used in the
treatment of contaminated groundwater or soils.  Tolman et al. (1978) has
described the conceptual design and in-situ detoxification of cyanide with
sodium hypochlorite.  The reaction of many organics with hypochlorite results
in the formation of chlorinated organics which can be as or more toxic than
the original contaminant.  The formation of lower molecular weight chlorinated
organics (e.g., trihalomethanes) in drinking water from hypochlorite treatment
for disinfection purposes has become a major concern of the drinking water
industry.


                                     9-53
-------
     Hydrogen peroxide (H,^)-), a moderate strength chemical oxidant, is used
routinely in municipal wastewater treatment to control various factors of
biological treatment, and is also used in industrial waste treatment to
detoxify cyanide and various organic pollutants.  Table 9-17, developed by
USEPA (1985), indicates chemical compound classes that may be degraded using
hydrogen peroxide.

     Hydrogen peroxide is commercially available in aqueous solutions of
several concentrations and is miscible in water at all concentrations.  It has
been delivered successfully in dilute solutions to the subsurface as an oxygen
source in a bioreclamation project (Raymond, Jamison, and Hudson, 1984) (see
Section 9.1).  One supplier has developed a line of hydrogen peroxide
solutions specifically designed for reclamation purposes (FMC, 1985).

     Chemical reduction is the process by which the oxidation state of a
compound is reduced.  Reducing agents are election donors, with reduction
accomplished by the addition of elections to the atom.

     Chemical reduction does not appears as promising as oxidation for the
treatment or organics.  Although reseaches have demonstrated reductive
dehalogenation of a variety of chlorinated organics and reduction of
unsaturate aromatics and aliphatics in laboratory studies using catalyzed
metal powders the treatment reagents are costly and the effectiveness of
chemical reduction in soils has not been demonstrated.

     Chemical reduction does, however, appear promising for treatment of
chromium and selenium in soils.  The in-situ reduction of hexavalent to
divalent chromium has been accomplished in Arizona well water using minute
quantities of reducing agent.  (Srivastava and Haji-Djafari, 1983).

     There are a number of disadvantages with the use of oxidizing and
reducing agents which limit their use at hazardous waste sites.  The treatment
compounds are non-specific and this may result in degradation of non-targeted
compounds.  There is the potential, particularly with oxidation, for the
formation of more toxic or more mobile degradation products.  Also, the
introduction of these chemicals into the groundwater system may create a
pollution problem in itself.  As with soil flushing, uncertainty exists with
respect to obtaining adequate contact with the contaminants in the plume.

     Enzymatic degradation of organics with cell-free enzymes holds potential
as a possible in-situ treatment technique.  Purified enzyme extracts,
harvested from microbial cells, are commonly used in industry to catalyze a
variety of reactions, including the degradation of carbohydrates and proteins.
A bacterial enzyme preparation has been used to detoxify organophosphate waste
from containers (Munnecke, 1980).  Parathion hydrolase has been tested under
field conditions in the degradation of the pesticide diazinon (Paulson et al.,
1984).  The studies indicate that parathion hydrolase can be used to effec-
tively reduce rapidly large concentrations of diazinon in soil.  The enzyme is
readily soluble in water, is reasonably stable at summer temperatures, and can
be easily handled in the field.  The pH or organic content of the soil does
not appear to affect the enzyme's effectiveness.  It appears from the study
                                     9-54
-------











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9-55
-------
that parathion hydrolase could be used effectively to clean up diazinon
spills, but more research is required to determine how to obtain optimal field
efficacy of the enzyme.

     Permeable treatment beds are essentially excavated trenches placed
perpendicular to groundwater flow and filled with an appropriate material to
treat the plume as it flows through the material (see Figure 9-7).  Some of
the materials that may be used in the treatment bed are limestone, crushed
shell, activated carbon, glauconitic green sands, and synthetic ion exchange
resins.  Permeable treatment beds have the potential to reduce the quantities
of contaminants present in leachate plumes.  The system is applicable to
relatively shallow groundwater tables containing a plume.  To date, the
application of permeable treatment beds at hazardous waste sites has not been
performed.  However, bench- and pilot-scale testing has provided preliminary
quantification of treatment bed effectiveness.  Potentially numerous problems
exist in using a permeable treatment bed.  These include saturation of bed
material, plugging of bed with precipitates, and short life of treatment
materials.  Therefore, permeable treatment should probably be considered as a
temporary remedial action rather than a permanent one.

     A limestone or crushed shell bed can be used to neutralize acidic ground-
water and retain certain metals such as cadmium, iron, and chromium.  The
effectiveness of limestone as a barrier depends primarily on the pH and volume
of the solution passing through the limestone (Artiola and Fuller, 1979).  The
nature of the heavy metal is also an important factor.  A laboratory study
demonstrated that limestone was more effective at retaining chromium III than
for chromium VI and other metals (Artiola and Fuller, 1979).

     Fuller and other researchers (USEPA, 1978) have discussed the use of
crushed limestone as an effective, low cost landfill liner to aid in attenu-
ating the migration of certain heavy metals from solid waste leachates.
According to the authors, dolomitic limestone (containing significant amounts
of magnesium carbonate) is less effective in removing ions than purer
limestone containing little magnesium carbonate.  Therefore, in the design of
a limestone treatment bed, limestone with high calcium content is recommended
to remove heavy metals and to neutralize contaminated groundwater.

     In regard to designing vertical permeable treatment beds, the particle
size of the limestone used should be selected dependent on the type of soil in
which groundwater flows (i.e., which controls flow rates) and the level of
contamination.  In general, a mixture of gravel-size and sand-size limestone
should be used to minimize settling through dissolution.  Where excessive
channelling through the bed by rapid groundwater movement is expected or where
improved contact time between the contaminated groundwater and the treatment
bed is required, a higher percentage of sand-size particles is more
appropriate.

     A variation on the use of limestone permeable treatment beds to neutral-
ize plumes is the use of limestone or crushed shell layered over a waste site
to indefinitely stabilize the disposed waste.  This approach will be used to
                                     9-56
-------
                FIGURE 9-7
INSTALLATION OF A PERMEABLE TREATMENT BED
                             Permeable Treatment Bed
                 9-57
-------
reduce solubility of metal hydroxides by maintaining highly alkaline
conditions in the waste (Francis, 1984).

     Activated carbon as a possible treatment bed material has the capability
of removing nonpolar organic compounds from contaminated plumes, but is not
practical for the removal of heavy metals.  Activated carbon will not remove
polar organics.  However, the high cost of activated carbon, the potential for
desorption of adsorbed compounds, and the likelihood of a short bed-life in
the presence of high waste concentrations make the use of activated carbon
beds cost-prohibitive under most circumstances.

     Glauconitic greensands have potential for the removal of heavy metals.
Bench-scale studies with leachate indicate that the highest removal effi-
ciencies are for copper, mercury, nickel, arsenic, and cadmium and that effi-
ciencies increase with contact time (Spoljaric, N. Delaware Geological Survey,
Newark, DE, personal communication, 1980).  With contact time in the field
being on the order of days, metal removal efficiencies may be extremely high.
Experiments indicate that the greensands may also have a high capacity for
heavy metal cation retention, even when flushed with solutions of highly
alkaline or acidic pH (Spoljaric, N. Delaware Geological Survey, Newark, DE,
personal communication, 1980).  An in-situ experiment in England (Ross, 1980)
demonstrated promising retention capabilities.  Glauconitic greensands appear
promising; however, more research is required to determine their sorptive
capacity and capability for treating higher concentrations of heavy metals.

     Advantages of glauconitic treatment beds, based on studies to date,
include good permeability, abundance in the Atlantic Coastal Plain (i.e., New
Jersey, Delaware, and Maryland), effectiveness in removal and retention of
many heavy metals, and good retention time characteristics for efficient
treatment.  Among the disadvantages of using glauconitic treatment beds are
unknown saturation characteristics and potential for plugging over time,
potential reduction in pH, limited to areas of natural occurrence such as the
mid-Atlantic region, and possibility of land purchase requirements as
glauconite is not commercially mined•


     9.2.6  Technology Selection/Evaluation


     This section described a wide range of chemical and in-situ treatment
methods, therefore, generalizations regarding the feasibility and effective-
ness of these methods are not possible.  However, all of these methods are
developmental or conceptual and none have been fully demonstrated for
hazardous waste site remediation.

     Of all the methods described, soil flushing methods involving the use of
water surfactants appear to be most feasible and cost-effective for organics.
They .can use relatively cheap, innocuous treatment reagents, can be used to
treat a broad range of waste constituents, and do not result in toxic degrada-
tion products.
                                      9-58
-------
     The most feasible methods for treating inorganics in-situ  include  soil
flushing with dilute acids, chelating agents or other treatment agents  which
will mibolize the metals.  Precipitation of the metals as  sulfides  or
phosphates, and the use of permeable treatment beds have potential  application
although there are potentially serious drawbacks with each of these methods.
For example, permeable treatment beds are prone to clogging, and sulfide
precipitation can clog soils and reduce permeability.

     Mention of these potential drawbacks should not preclude consideration of
in-situ methods.  However, laboratory- and possibly pilot-scale testing is
likely to be required in each case, resulting in delays in implementing the
remedial action.

     As with biological treatment methods, chemical treatment methods used to
deliver and recover treatment reagents also affect the reliability  of these
methods.  Reliability of pumping and subsurface drainage systems have been
described previously.

     Again, worker safety considerations are the same as those  related  to
in-situ biological treatment methods involving a potentially hazardous
chemical reagent.  The same precautions required when working with  hydrogen
peroxide (Section 9.1.6) are required when working with acids,  bases,
surfactants, and other potentially hazardous reagents.
     9.2.7  Costs
     Costs for the chemical in-situ treatment approaches discussed in this
section are difficult to estimate since these methods have largely not been
demonstrated at hazardous waste sites and no actual cost data are available.
In-situ treatment costs are variable, but could be less than excavation and
removal methods and/or pump and treat methods.  As with removal, in-situ
approaches are conducted on a one-time basis, so there are generally no
long-term operation and maintenance costs.

     Costs for the chemical treatment approaches involving the delivery of a
reagent to the subsurface (soil flushing, various immobilization techniques,
neutralization, hydrolysis, oxidation, reduction, and enzymatic degradation)
will depend on the amount of material to be treated, the amount of chemical
reagent required, the costs for the delivery system (injection wells or
infiltration galleries), the chemical and feed system, and fees for probing,
excavation, and drilling.  Costs for laboratory- and pilot-scale studies
should also be considered when performing such a treatment approach.  Soil
flushing, which involves bringing contaminated water to the surface for
treatment, would require a wastewater treatment system.  Costs for the drains
and pumping are presented in Sections 5.1 and 5.2, respectively.  Table 9-10
provides unit costs for chemicals.

     1985 unit costs for the installation of a permeable treatment bed are
shown in Table 9-18.  Total closure costs for stabilizing approximately 8,000


                                     9-59
-------
                                  TABLE 9-18.
           UNIT COSTS FOR INSTALLATION OF A PERMEABLE TREATMENT BED
   Item
     Assumptions
    Costs
Trench excavation
Spreading
Well-point dewatering
Sheet piling
Walers, connections,
  struts

Liner
Limestone
20 ft deep, 4 ft wide,
by backhoe

Spread by dozer to grade
trench and cover

500 ft header 8" diameter,
for one month

20 feet deep; pull
and salvage

2/3 salvage
30 mil PVC
30 mil CPE

Mixed "gravel size" and
"sand size"

Installation
(Backfill trench,
100 foot haul)
$1.40 cubic yard
$l/cubic yard
$115/linear foot
$7.70/square foot
$165/ton
$0.25-0.35/square foot
$0.35-0.45/square foot

$30-45/ton3
                                                       $3.70/cubic yard
-Godfrey, 1984; Costs are total, including contractor overhead and profit.
-Godfrey, 1984; Materials only.
fSchnell, 1985.
 Cope, Karpinski, and Steiner, 1984.
                                     9-60
-------
cubic yards of sludge contaminated with nickel hydroxide by covering the site
with a I inch layer of calcium carbonate are estimated at $100,000 to
$200,000, compared with $900,000 to $1 million estimated for excavation and
removal (Francis, 1984).


9.3  Physical In-Situ Methods


     9.3.1  General Description
     A number of methods are currently being developed which involve physical
manipulation of the subsurface in order to immobilize or detoxify waste
constituents.  These technologies, which include in-situ heating, vitrifica-
tion and ground-freezing, are in the early stages of development and detailed
information is not available.

     In-situ heating has been proposed as a method to destroy or remove
organic contaminants in the subsurface through thermal decomposition, vapori-
zation, and distillation.  Methods recommended for in-situ heating are steam
injection (Hoogendorn, 1984) and radio frequency heating (Dev, Bridges, and
Sresty, 1984).

     The radio frequency heating process has been under development since the
1970s.  Field experiments have been conducted for the recovery of hydro-
carbons.  The method involves laying a row of horizontal conductors on the
surface of a landfill and exciting them with an RF generator through a
matching network.  The decontamination is accomplished in a temperature range
of 300° to 400°C, assisted with steam, and requires a residence time of about
two weeks.  A gas or vapor recovery system is required on the surface.  Exca-
vation, mining, drilling, or boring is not required.  Field tests found that
leakage radiation levels did not exceed the recommended ANSI Standard C-95.
Preliminary design and cost estimates for a mobile RF in-situ decontamination
process (see Section 9.2.5) indicate that the method is 2 to 4 times cheaper
than excavation and incineration (Dev, Bridges, and Sresty, 1984).  This
method appears very promising for certain situations involving contamination
with organics, although more research is necessary to verify the effectiveness
in-situ.

     Artificial ground freezing involves the installation of freezing loops in
the ground and a self-contained refrigeration system that pumps coolant around
the freezing loop (Sullivan, Lynch and Iskandar, 1984).  Although never used
in an actual waste containment operation, the technology is being used
increasingly as a construction method in civil engineering projects.
Artificial ground freezing is done not on the waste itself, which may have a
freezing point much lower than that of the soil systems, but on the soil
surrounding the hazardous waste.  It renders the soil practically impermeable,
but is useful only as a temporary treatment approach because of the thermal
maintenance expense (Sullivan, Lynch, and Iskandar, 1984).
                                     9-61
-------
     In-situ vitrification is a technology being developed for the stabiliza-
tion of transuranic contaminated wastes, and is conceivably applicable to
other hazardous wastes (Fitzpatrick et al., 1984).  Several laboratory-scale
and pilot-scale tests have been conducted, and a large-scale testing system is
currently being fabricated.  The technology is based upon electric melter
technology, and the principle of operation is joule heating, which occurs when
an electrical current is passed through a molten mass.  Contaminated soil is
converted into durable glass, and wastes are pyrolyzed or crystallized.  Off-
gases released during the melting process are trapped in an off-gas hood.  The
depth of the waste is a significant limiting factor in the application of this
technology:  1 to 1.5 meters of uncontaminated overburden lowers release
fractions considerably (Fitzpatrick et al., 1984).

     Cost estimates for five in-situ vitrification large-scale configurations
are provided in Table 9-19 (Fitzpatrick et al., 1984, citing Oma et al.).
These cost comparisons are based on vitrifying to a depth of 15 feet.  Of
these costs, approximately 30 to 46 percent is for power, 10 to 13 percent is
for equipment, 36 to 45 percent is for labor, and 5 to 10 percent is for
electrodes (Banning, 1984).  Soil moisture can increase operating costs by
increasing requirements because the water in the soil must be evaporated.
Estimates for treating a humid site in the eastern United States is near
$85/cubic foot (1982 dollars) (Sanning, 1984).

     The cost of a hypothetical hazardous waste site decontaminated by radio
frequency heating was estimated for a 1 acre landfill area with contamination
extending to 20 feet (Dev, Bridges, and Sresty, 1984).  Volatile matter in the
landfill was assumed to range from 5 to 20 percent by weight, with 10 percent
of the total volatile matter being organic.  Total capital costs for a
purchase power option was estimated at approximately $17 million.  The capital
costs increase to $27.5 million if the power is generated on-site.  Capital
costs for equipment for excavation and incineration were estimated at
$832,000.  The total costs of decontamination (including operating costs but
not capital costs) was estimated to be between $4.6 and $5.7 million for radio
frequency heating (purchased power plant).  Total treatment costs for
incineration (excluding capital costs) were estimated at between $9 and $25.2
million (Dev, Bridges, and Sresty, 1984).

     Figure 9-8 provides estimated costs for ground freezing plotted as a
function of freezing rod space for a hypothetical site.  The site requires a
1,000 foot frozen wall which is 3 feet thick and is placed down to depth of
bedrock (40 feet).  The site is assumed to be located in coarse quartz sand,
150 miles from the drilling and refrigeration contractors.  From Figure 9-5,
one can see that as the drill space becomes tighter, the fuel costs, equipment
rentals, and time for wall completion are reduced.  A tight drill space yields
small frozen soil column radii and permits use of less expensive refrigeration
equipment.  The drawback of close drill spacing is the expense associated with
the drilling operation.  The linear footage of piping, a drive shoe for each
well drilled, and the labor charge per vertical foot drilled overwhelm all
other economic parameters.  Analysis of costs for this hypothetical site
illustrated that ground/freezing is only applicable as a short-term remedial
measure (Sullivan, Lynch, and Iskandar, 1984).


                                     9-62
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                                  TABLE 9-19.
 1982 COST ESTIMATES FOR FIVE IN-SITU VITRIFICATION LARGE-SCALE CONFIGURATIONS



Number
1
2

3

4
5


Site
Hanford
Hanford

Hanford

Generic
Generic


Power
Local
Local

Local

Local
Portable


Heat Loss
High
Average

Average

Average
Average

Manpower
Level
Average
Average

Above
Average
Average
Average
Total Cost
of Soil
Vitrified
$187/m3
$161/m3
3
$183/m

$180/m3
$224/m3
Total Cost
of Soil
Vitrified
$5.30/ft2
$4.60/ft2
2
$5.20/ft

$5.10/ft2
$6.30/ft2

Source:  Fitzpatrick et al., 1984
                                     9-63
-------
                          FIGURE  9-8
         ECONOMIC OVERVIEW OF GROUND FREEZING FOR
                      A HYPOTHETICAL SITE
    500 _.


    400 -


8  sooj
5

I  200 J


    100 L
                      FROZEN WALL 1000 X 3 X 40 FT
             SOLID   - OVERALL COST
             _._._   - DRILL EXPENSE
             	   - FUEL COSTS
             	   - EQUIPMENT RENTAL
             	- DAYS
                                                      -50
                                                        30D
                                                          A
                                                          Y
                                                          S
                       4         6         8

                         DRILL SPACING (FT)
                                                 10
Source: Sullivan, Lynch, and Iskandar, 1984
                              9-64
-------
                                  REFERENCES
Artiola, J., and W.H. Fuller.  1979.  Effects of Crushed Limestone Barriers on
Chromium Attenuation in Soils.  Journal of Environmental Quality.  Vol. 9, No.
4.  pp. 503-510.

Barakat, Y., L.N. Fortney, R.S. Schechter, W.H. Wade, and S.H. Yiv.   1983.
Criteria for Structuring Surfactants to Maximize Solubilization of Oil  and
Water.  J. Colloid Interface Sciences.  Vol. 92, No. 2.
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-------
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                                     9-66
-------
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Huibregtse, K.R., J.P. LaFornara, and K.H. Kastman.  1978.   In  Situ
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Jamison, V.W., R.L. Raymond, and J.O. Hudson.  1976.  Biodegradation of
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Chemical Manufacturer's Association, Washington, DC.

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JRB Associates/SAIC.  1985.  Field Demonstration Plan for In-Situ Treatment of
Contaminated Groundwater and Soils, Kelly AFB, TX.   Prepared  for:  USEPA
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Kufs, C., P. Rogeshewski, E. Repa, and N. Barkley.   1982.   Alternatives to
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Lee, M.D. and C.H. Ward.  1984.  Reclamation of  Contaminated  Aquifers,
Biological Techniques.  In:  1984 Hazardous  Material  Spills Conference
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Litchfield, J.H. and L.C. Clark.  1973.  Bacterial Activity in Groundwaters
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Lyman, Reehl, and Rosenblatt.  1982.  Handbook of Chemical  Property  Estimation
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Metcalf and Eddy, Inc.  1972. Wastewater Engineering:  Collection, Treatment,
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                                     9-67
-------
                            REFERENCES (continued)


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                                     9-68
-------
                            REFERENCES (continued)


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                                     9-69
-------
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USEPA.  1984a.  Review of In-Place Treatment Techniques for Contaminated
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USEPA.  1984b.  Case Studies 1-23:  Remedial Response at Hazardous Waste
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                                     9-70
-------
                            REFERENCES (continued)
Wilson, J.T., J.F. McNabb, B.H. Wilson, and M.J. Noonan.   1983.
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                                     9-71
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                                  SECTION  10

                            DIRECT WASTE TREATMENT
     This section describes direct waste treatment methods  applicable  for
treating aqueous, gaseous, and solid waste streams produced  at hazardous waste
sites.  Many of the treatment methods described  in this  section  are widely
used in industrial waste treatment applications  and  information  on their
design and construction is well described in the literature  cited throughout
the section.  As a result detailed information pertaining to design and
construction has not been included.  Instead, this section emphasizes
applications and limitations of these methods for hazardous  waste treatment.
Section 10.1 describes aqueous waste treatment methods.  Section 10.2
describes methods for solid waste treatment including solids separation and
dewatering methods.  Section 10.3 addresses solidification and stabilization
technologies applicable for liquid and solid wastes.  Commonly used methods
for treating gaseous emissions (with the exception of incineration) are
addressed in Section 10.4  Incineration and other thermal treatment methods
are addressed separately in Section 10.5 since these methods apply to  liquid,
solid, and gaseous wastes.
10.1  Aqueous Waste Treatment


     Aqueous waste streams resulting from the clean up of hazardous waste
sites vary widely with respect to volume, level, and type of contaminants and
level of solids.  The major sources of aqueous wastes include:

     •  Leachate plumes which have been pumped to the surface or collected via
        subsurface drains

     •  Contaminated water generated during dredging operations

     •  Contaminated run-off collected in impoundments or basins

     •  Contaminated water generated from equipment cleanup

     •  Aqueous waste generated from sediment or sludge dewatering

     •  Highly concentrated wastewater streams generated from certain aqueous
        waste treatment processes (e.g., backwash from filtration, concentrate
        from reverse osmosis).
                                     10-1
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     Because these waste streams are so diverse in volume, type, and concen-
tration of contaminants, a wide variety of treatment processes will have
application to hazardous waste site cleanup.  This section addresses those
processes which are considered most applicable for hazardous waste site
remediation.  Rarely will any one unit treatment process be sufficient for
aqueous waste treatment.  Therefore, the discussions which follow include
information on unit treatment processes which are frequently used in combina-
tion and any pretreatment requirements which are a prerequisite to effective
use of each treatment process.  The unit treatment processes considered in
this section include:

     •  Activated carbon
     •  Activated sludge
     •  Filtration

     •  Precipitation/flocculation
     •  Sedimentation

     •  Ion exchange
     •  Reverse osmosis

     •  Neutralization
     •  Gravity separation

     •  Air stripping
     •  Chemical oxidation

     •  Chemical reduction.

     Aqueous waste treatment at hazardous waste sites can be accomplished
using one of four general approaches:

     •  On-site treatment using mobile treatment system
     •  On-site construction and operation of treatment systems
     •  Pretreatment followed by discharge to a POTW

     •  Hauling of waste to an off-site treatment facility.

     Mobile treatment systems and systems constructed on-site have broadest
applicability.  Wastewaters discharged to POTWs often require extensive
pretreatment in order for the facility to meet its NPDES permit conditions.
Other factors which determine the feasibility of POTW discharge include
whether the facility has the hydraulic capacity to handle the waste, whether
accepting the waste will result in additional monitoring requirements or
process changes, and the potential for opposition in the community.

     Hauling wastes off-site  for treatment  is limited to all but very small
wastewater volumes.
                                      10-2
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     10.1.1  Activated Carbon Treatment
          10.1.1.1  General Description


     The process of adsorption onto activated carbon  involves  contacting  a
waste stream with the carbon, usually by flow through a series of packed  bed
reactors.  The activated carbon selectively adsorbs hazardous  constituents by
a surface attraction phenomenon in which organic molecules are attracted  to
the internal pores of the carbon granules.

     Adsorption depends on the strength of the molecular attraction between
adsorbent and adsorbate, molecular weight, type and characteristic of
adsorbent, electrokinetic charge, pH, and surface area.

     Once the micropore surfaces are saturated with organics,  the carbon  is
"spent" and must either be replaced with virgin carbon or removed, thermally
regenerated, and replaced.  The time to reach "breakthrough" or exhaustion is
the single most critical operating parameter.  Carbon longevity balanced
against influent concentration governs operating economics.

     Most hazardous waste treatment applications involve the use of adsorption
units which contain granular activated carbon (GAG) and operate in a downflow
series mode such as that shown in Figure 10-1 (Brunotts et al., 1983).

     The downflow fixed bed series mode has been found to be generally most
cost-effective and produces the lowest effluent concentrations relative to
other carbon adsorber configurations (e.g., downflow  in parallel, moving  bed,
upflow-expanded).   The units may be connected in parallel to provide increased
hydraulic capacity.


          10.1.1.2  Applications/Limitations


     Activated carbon is a well developed technology which is widely used in
the treatment of hazardous waste streams.  It is especially well suited for
removal of mixed organics from aqueous wastes.  Table 10-1 provides an
indication of the treatability of organics commonly found in groundwater.

     Table 10-2 delineates various factors which influence the applicability
of activated carbon treatment for any given waste (Nalco Chemical Co., 1979).
As carbon adsorption is essentially an electrical interaction phenomenon, the
polarity of the waste compounds will largely determine the effectiveness  of
the adsorption process.  Highly polar molecules cannot be effectively removed
by carbon adsorption.  Another factor to consider in determining the likely
effectiveness of carbon adsorption is aqueous solubility.  The more hydro-
phobic (insoluble) a molecule is, the more readily the compound is adsorbed.
Low solubility humic and fulvic acids which may be present in the groundwater
can sorb to the activated carbon more readily than most waste contaminants and
result in rapid carbon exhaustion.

                                     10-3
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                                   FIGURE 10-1.
               TWO-VESSEL GRANULAR CARBON ADSORPTION SYSTEM
            FEED WATER
    REGENERATED/MAKEUP
      ACTIVATED CARBON
         BACKWASH EFFLUENT
          BACK WASH FEED
                         ADSORBER I
                                             ADSORBER 2
REGENERATED/MAKEUP
ACTIVATED CARBON
                                                       BACK WASH EFFLUENT
                                                         BACK WASH FEED
                                                   TREATED EFFLUENT
                         SPENT CAHBON
      VALVE CLOSED

      VALVE OPEN
        Source: USEPA, 1973a
     In addition,  some metals and  inorganic species have  shown excellent to
good adsorption potential, including  antimony, arsenic, bismuth,  chromium,
tin, silver, mercury, cobalt, zirconium,  chlorine, bromine,  and iodine.

     Carbon  adsorption is frequently  used following biological treatment
and/or granular media filtration  in order to reduce the organic and suspended
solids load  on the carbon columns, or to remove refractory organics which
cannot be  biodegraded.  Air  stripping may also be  applied prior to carbon
adsorption in  order to remove a portion of the volatile contaminants, thereby
reducing  the organic load to the  column.  These pretreatment steps all
minimize  carbon regeneration costs.

     The  highest concentration of  solute in the influent  stream that has been
treated on a continuous basis is  10,000 ppm total  organic carbon (TOC), and  a
1 percent  solution is currently considered as the  upper limit (De Renzo,
                                       10-4
-------
                                  TABLE 10-1.

                  FACTORS AFFECTING EQUILIBRIUM ABSORBABILITY
     Compound Adsorbability Favored by:
          Increasing carbon chain length
          Increasing aromaticity
          Decreasing polarity
          Decreasing branching
          Decreasing solubility
          Decreasing degree of dissociation
     Functionality
          Relative adsorbability:  acids > aldehydes > esters > ketones >
          alcohols > glycols when number of carbon atoms is <4
     pH Effects
          Undissociated species are mo're easily adsorbed                    ,
          - low pH favors adsorption of acids (e.g., volatile acids, phenol)
          - high pH favors adsorption of bases (e.g., amines)
          Other compounds:  adsorption can be favored by higher pH
          - Postulated general effect:
                     Partial neutralization of surface acidity reduces
                     hydrogen-bonding of surface groups eliminating steric
                     blockage of micropores
     Temperature
          Increased temperatures can increase rate of adsorption due to
            viscosity and diffusivity effects
          Exothermic adsorption reactions are favored by decreasing
            temperatures, usually a minor effect on equilibrium level
 When the rate is controlled by intraparticle transport, decreasing molecular
 size would result in faster rate, all else being equal.

 This often is the most significant pH effect, so adsorption generally is
 increased with decreasing pH;
Source:  Conway and Ross, 1980.
                                      10-5
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                                  TABLE 10-2.

                          CARBON INFLUENT AND EFFLUENT
Organic Compounds
in Groundwater
 Number of
Occurrences
  Influent*
Concentration
    Range
   Carbon
  Effluent*
Concentration
  Achieved
Carbon tetrachloride                 4
Chloroform                           5
DDD                                  1
DDE                                  1
DDT                                  1
CIS-l,2-dichloroethylene             8
Dichloropentadiene                   1
Disopropyl ether                     2
Tertiary methyl-butylether           1
Diisopropyl methyl phosphonate       1
1,3-dichloropropene                  1
Dichlorethyl ether                   1
Dichloroisopropylether               1
Benzene                              2
Acetone                              1
Ethyl acrylate                       1
Trichlorotrifloroethane              1
Methylene chloride                   2
Phenol                               2
Orthochlorophenol                    1
Tetrachloroethylene                 10
Trichloroethylene                   15
1,1,1-trichloroethane                6
Vinylidiene chloride                 2
Toluene                              1
Xylene                               3
             130 ug/1-10 mg/1
             20 ug/1-3.4 mg/1
                       1 ug/1
                       1 ug/1
                      4 ug/11
                5 ug/1-4 mg/1
                     450 ug/1
                   20-34 ug/1
                      33 ug/1
                   1,250 ug/1
                      10 ug/1
                     1.1 mg/1
                     0.8 mg/1
                  0.4-11 mg/1
                  10-100 ug/1
                     200 mg/1
                       6 mg/1
                    1-21 mg/1
                      63 mg/1
                     100 mg/1
               5 ug/1-70 mg/1
                 5 ug-16 mg/1
              60 ug/1-25 mg/1
                5 ug/1-4 mg/1
                     5-7 mg/1
                  0.2-10 mg/1
                    <0
                    <0
     .05
     .05
     .05
     ug/1
     ug/1
      g/1
     ug/1
     ug/1
  <1 ug/1
 <10 ug/1
  <1 ug/1
<5.0 ug/1
 <50 ug/1
  <1 ug/1
  <1 ug/1
  <1 ug/1
  <1 ug/1
 <10 mg/1
  <1 mg/1
 <10 ug/1
<100 ug/1
  <1 ug/1
  <1 mg/1
     ug/1
     ug/1
     ug/1
     ug/1
     ug/1
     ug/1
*Analyses conducted by Calgon Carbon Corporation conformed to published U.S.
 EPA protocol methods.  Tests in the field were conducted using available
 analytical methods.

Source:  O'Brien and Fisher, 1983
                                    10-6
-------
1978).  Pretreatment is required  for  oil  and  grease  and  suspended solids.
Concentrations of oil and grease  in the  influent  should  be  limited to 10 ppm.
Suspended solids should be  less than  50  ppm for upflow systems,  while downflow
systems can handle much higher solids  loadings.


          10.1.1.3  Design  Considerations


     The phenomenon of adsorption is  extremely complex and  not mathematically
predictable.  To accurately predict performance,  longevity  and operating
economics, field pilot plant studies  are  necessary.

     In order to conduct an initial estimate  of carbon column  sizing,  the
following data need to be established  during  pilot plant  testing:

     •  Hydraulic retention time  (hours)
     •  Flow (gallons/minute)
     •  Hyraulic capacity of the  carbon  (gallons  waste/pound carbon)
     •  Collected volume of treated waste  at  breakthrough (gallons)
     •  Carbon density (pounds carbon/cubic foot).

     In the above data list, the  term  "breakthrough"  refers to the moment  when
the concentration of solute being treated  first starts to rise in the carbon
unit effluent.  The term "exhaustion"  refers  to the moment  when  the
concentration of solute being treated  is  the  same in  both effluent and
influent.
          10.1.1.4  Technology Selection/Evaluation


     Activated carbon is an effective and reliable means of  removing  low
solubility organics.  It is suitable for treating a  wide range  of  organics
over a broad concentration range.  It is not particularly  sensitive to  changes
in concentrations or flow rate and, unlike biological  treatment,  is not
adversely affected by toxics.  However, it is quite  sensitive to  suspended
solids and oil and grease concentrations.

     Activated carbon is easily implemented into more  complex treatment sys-
tems.  The process is well suited to mobile treatment  systems as well as to
on-site construction.  Space requirements are small, start-up and  shut-down
are rapid, and there are numerous contractors who are  experienced  in  operating
mobile units.

     The EPA's Mobile Physical/Chemical Treatment System includes  three carbon
columns that can be operated either in series or in  parallel and are  designed
for a hydraulic loading of 200 gpm with a 27 minute  contact  time.  This
contact time has been found to be adequate for many  hazardous waste streams.


                                     10-7
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However,  longer contact  times  can be  provided by  reducing  the  hydraulic flow
rate (Ghassemi, Yu, and  Quinlivan,  1981).

     Use  of several carbon  adsorption columns at  a  site  can  provide  con-
siderable flexibility.   Various  columns  can  be  arranged  in series  to increase
service life between regeneration of  the  lead bed or  in  parallel  for maximum
hydraulic capacity.  The piping  arrangement  would allow  for  one  or more beds
to be regenerated while  the other columns  remain  in  service.

     The  most obvious maintenance consideration associated with  activated
carbon treatment is the  regeneration  of  spent carbon  for reuse.  Regeneration
must be performed for each  column at  the  conclusion  of its bed-life  so  the
spent carbon may be restored as  close as  possible to  its original  condition
for reuse; otherwise, the carbon must  be  disposed of.  Other operation  and
maintenance requirements of activated  carbon technology  are minimal  if
appropriate automatic controls have been  installed.

     It is recommended that the  thermal destruction  properties of  waste
chemicals be determined  prior  to selection of activated  carbon treatment
technology, since any chemicals  sorbed to  activated  carbon must eventually  be
destroyed in a carbon regeneration  furnace.  Therefore,  of crucial importance
to the selection of activated  carbon  treatment  is whether  the  sorbed waste
material  can be effectively destroyed  in  the regeneration  furnace; otherwise,
upon introduction to the  furnace, they will  become  air pollutants.

     The  biggest limitation of the  activated carbon  process  is the high
capital and operating cost.  As  described  previously, the  operating  costs can
be substantially reduced by pretreatment  of  the waste using  biological
treatment or air stripping.
          10.1.1.5  Costs
     The cost of activated carbon units depends  on  the  size  of  the  contact
unit which is influenced by the concentrations of the target  and  non-target
organic compounds  in the waste stream  and  the desired level  of  target
compounds in the effluent.  Table 10-3 presents  construction, operation and
maintenance  costs  for cylindrical pressurized,  downflow steel  contactors
based on a nominal  detention time of 17.5 minutes and a carbon  loading  rate  of
5gpm/ft .  The construction costs include housing,  concrete  foundation, and
all the necessary  pipes, valves, and nozzles for operating the  unit  plus the
initial change of  carbon.  The operation and maintenance cost  include  the
electricity and assume carbon replacement once a year.   However,  systems for
unloading spent carbon and loading fresh carbon  are not included.

     There are a number of manufacturers such as Calgon Carbon  Corporation who
market mobile activated carbon treatement  systems.   For example,  Calgon Carbon
Corporation has a  trailer-mounted carbon adsorption treatment unit  that can  be
shipped to a treatment location within 24 to 48  hours.   The  system  can  be
configured wih either single or multiple pre-piped  adsorber vessels.   It can
handle flow of up  to 200 gpm.  The following describes  costs  associated with a

                                     10-8
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                                  Table 10-3
    GENERAL COST DATA FOR VARIOUS SIZES OF ACTIVATED CARBON CONTACT UNITS
 Capacity (gpra)     Column        Column    Housing  Construction        O&M
                Diameter (ft)  Length (ft) Area (ft )   Costs*    Costs  ($/yr)*
1.7
17
70
175
350
0.67
2
4
6.5
9
5
5
5
5
5
60
150
300
375
450
12,320
23,776
42,425
64,000
93,822
1,690
2,315
4,800
8,110
12,540

*Updated from 1979 to 1984 dollars using third quarter Marshall and Swift
 Equipment Index.

Source:  Adapted from Hansen, Gumerman, and Gulp, 1979.
                                      10-9
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mobile system consisting of two 10-foot diameter,  10-foot high,  skid mounted
vessels capable of handling up to 200 gpm (Calgon  Corp, undated):

     Delivery, supervision of installation             $25,000
     and startup, tests to conduct re-
     activation of carbon, dismantling and
     removal of system (including freight to
     and from the site)

     Delivery and removal of one truck-               $15,200
     load of carbon (2,000 Ibs)

     (Two truckloads required for a
     two-vessel system) - Rental fee (per month)      $5,000/month

     Calgon Carbon Corporation will take spent carbon back  for reactivation.
Otherwise, disposal costs for spent carbon must be added.
     10.1.2  Biological Treatment


          10.1.2.1  General Description


     The function of biological treatment is to remove organic matter  from  the
waste stream through microbial degradation.  The most prevalent  form of
biological treatment is aerobic, i.e., in the presence of oxygen.   A number of
biological treatment processes exist which may be  applicable  to  treatment of
aqueous wastes from hazardous waste sites, including conventional  activated
sludge, various modifications of the activated sludge process  including  pure
oxygen activated sludge, extended aeration, and contact  stabilization,  and
fixed film systems which include rotating biologial discs,  and trickling
filters.

     In the conventional activated sludge process, aqueous  waste flows  into an
aeration basin where it is aerated for several hours.  During  this time, a
suspended active microbial population (maintained  by recycling sludge)
aerobically degrades organic matter in the stream  along  with  producing  new
cells.  A simplified equation for this process is  shown  below:

          Organics + 02       >      CO- + H~0 + new cells

The new cells produced during aeration form a sludge which  is  settled  out  in a
clarifier.  A portion of the settled sludge is recycled  to  the aeration  basin
to maintain the microbial population while the remaining sludge  is wasted,
i.e., it undergoes volume reduction and disposal.  Clarified  water flows to
disposal or further processing.
                                      10-10
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     In the pure oxygen activated  sludge  process,  oxygen  or  oxygen-enriched
air is used instead of air to  increase  the  transfer  of  oxygen.   Extended
aeration involves longer detention times  than  conventional activated  sludge
and relies on a higher population  of microorganisms  to  degrade wastes.
Contact stabilization involves only short contact  of  the  aqueous wastes and
suspended microbial solids, with subsequent  settling  of sludge and  treatment
of the sludge to remove sorbed organics.  Fixed  film  systems  involve  contact
of the aqueous waste stream with microorganisms  attached  to  some inert medium
such as rock or specially designed plastic material.  The original  trickling
filter consisted of a bed of rocks over which  the  contaminated water  was
sprayed.  The microbes forming a slime  layer on  the  rocks, would metabolize
the organics, while oxygen was provided as  air moved  countercurrent from  the
water flow (Canter and Knox, 1985).

     Biological towers are a modification of the trickling filter.  The medium
(e.g., of polyvinyl chloride (PVC), polyethylene,  polystyrene, or redwood) is
stacked into towers which typically reach 16 to  20 ft.  The  contaminated  water
is sprayed across the top and, as  it moves downward,  air  is  pulled upward
through the tower.  A slime layer  of microorganisms  forms on  the media and
removes the organic contaminants as the water  flows over  the  slime layer.

     A rotating biological contactor (RBC) consists of  a  series of rotating
discs, connected by a shaft, set in a basin or trough.  The contaminated  water
passes through the basin where the microorganisms, attached  to the discs,
metabolize the organics present in  the water.  Approximately  40% of the disc's
surface area is submerged.  This allows the slime  layer to alternately come in
contact with the contaminated water and the air where oxygen  is provided  to
the microorganisms (Canter and Knox, 1985).


          10.1.2.2  Applications/Limitations


     There is considerable flexibility  in biological  treatment because of the
variety of available processes and  adaptability of the microorganisms them-
selves.  Many organic chemicals are considered biodegradable, although the
relative ease of biodegradation varies widely.  Several generalizations can be
made with regard to the ease of treatability of organics  by aerobic biological
treatment:

     •  Unsubstituted nonaromatics or cyclic hydrocarbons are preferred over
        unsubstituted aromatics

     •  Materials with unsaturated bonds such as alkenes  are  preferred over
        materials with saturated bonds

     •  Soluble organics are usually more readily  degraded than insoluble
        materials.   Biological treatment is more efficient in removing
        dissolved or colloidal materials,  which are more  readily attacked by
        enzymes.   This is not the case, however, for  fixed film treatment
        systems which preferentially treat suspended matter
                                     10-11
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     •  The presence of functional groups affects biodegradability.  Alcohols,
        aldehydes, acids, esters, amides, and amino acids are more degradable
        than corresponding alkanes, olefins, ketones, dicarboxylic acids,
        nitriles, and chloroalkanes

     •  Halogen-substituted compounds are the most refractory to
        biodegradation; chlorinated alphatics are generally more refractory
        than the corresponding aromatics, although the number of halogens and
        their position is also significant in determining degradation.

     •  Nitro-substituted compounds are also difficult to degrade  although
        they are generally less refractory than the halogen-substituted
        compounds.

     Although there are a number of compounds which are considered to be
relatively resistant to biological treatment, it is recommended in practice
that the treatability of waste be determined through laboratory Biological
Oxygen Demand (BOD ) tests on a case-by-case basis.  Section 9.1 provides
further discussion of the degradability of organics.

     Despite the fact that industrial type wastes may be refractory to bio-
logical treatment, microorganisms can be acclimated to degrade many compounds
that are initially refractory.  Similarly, while heavy metals are  inhibitory
to biological treatment, the biomass can also be acclimated, within limits, to
tolerate elevated concentrations of metals.

     In terms of the variety of biological treatment processes available,
Table 10-4 presents the applications and limitations of each.  The completely
mixed activated sludge process is the most widely used for treatment of
aqueous wastes with relatively high organic loads.  However, the high purity
oxygen system has advantages for hazardous waste site remediation.

     In addition, a number of other parameters may influence the performance
of the biological treatment system, such as concentration of suspended solids,
oil and grease, organic load variations, and temperature.  Table 10-5 lists
parameters that may limit system performance, limiting concentrations, and the
type of pretreatment steps required prior to biological treatment.


          10.1.2.3  Design Considerations


     Design of the activated sludge or  fixed-film systems for a particular
application can be achieved best by first representing the system  as a
mathematical model, and then determining the necessary coefficients by running
laboratory or pilot tests.
                                     10-12
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                                  TABLE 10-4.

      SUMMARY OF APPLICATIONS/LIMITATIONS FOR BIOLOGICAL TREATMENT PROCESS
PROCESS
APPLICATIONS/LIMITATIONS
Conventional
Completely-mixed
Conventional

Extended Aeration
Contact Stabilization

Pure Oxygen



Trickling Filters



Rotating Biological Disc
Applicable to low strength wastes; subject to
shock loads

Resistant to shock loads
Requires low organic load and long detention
times; low volume of sludge; available as package
plant

Not suitable for soluble BOD

Suitable for high strength wastes;
low sludge volume;
reduced aeration tank volume

More effective for removal of colloidal and
suspended BOD; used primarily as a roughing
filter

Can handle large flow variations and high organic
shock loads; modular construction provides
flexibility to meet increases or decreased
treatment needs.
                                     10-13
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                                 TABLE   10-5

        CONCENTRATION OF  POLLUTANTS THAT MAKE  PREBIOLOGICAL
                     OR PRIMARY TREATMENTS DESIRABLE
Pollutant or
System Condition
Limiting
Concentration
                                                     Kind  of Pretreatment
Suspended solids


Oil or grease


Toxic ions

  Pb
  Cr

pH

Alkalinity



Acidity

Organic load variation

Sulfides


Phenols


Ammonia



Dissolved salts

Temperature
                            >50-125 mg/1
                            flotation, lagooning

                            >35-50 mg/1
                            £0.1 mg/1
                            <1 mg/1
                            P mg/1
                            <_ 10 mg/1

                            <6, >9

                            0.5 Ib alkalinity
                            as CaCO /Ib BOD
                            removed

                            Free mineral acidity
                            MOO mg/1


                            >70-300 mg/1


                            >1.6 g/1



                            >10-16 g/1

                            13-38'C in reactor
                        Sedimentation,
                        Skimming tank or
                        separator

                        precipitation or ion
                        exchange
                        Neutralization

                        Neutralization for
                        excessive alkalinity
                        Neutralization

                        Equalization

                        Precipitation or
                        stripping with recovery

                        Extraction, adsorption,
                        internal dilution

                        Dilution, ion exchange,
                        pH adjustment and
                        stripping

                        Dilution, ion exchange

                        Cooling, steam addition
Source:   Conway  and Ross, 1980
                                    10-14
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     The  following models have been  found  to  be  reliable  for  designing
biological treatment  systems  for waste  streams containing priority pollutants
(Cantor and Knox, 1985).

     Activated Sludge:

                    FS./X
               V =
                   U    S. - 1C
                    max   i    B
                   S. - S
                    i     e
     Biological Tower and Rotating Biological  Contactor:
                    FS.
                      i
                    U    S.
                     max  i  - K,,
                                B
                    S. - S
                     i    e
                                           •j
where     V  = volume of aeration tank ( f t )
          F  = flow rate (ft /day)
          X  = mixed liquor volatile solids (mg/1)
          S. = influent BOD, COD, TOC, or  specific organics  (mg/1)
          S1 = effluent BOD, COD, TOC, or  specific organics  (mg/1)
U    and  K  = biokinetic constants (day   )
          A  = surface area of biological  tower or rotating  biological
               contactor ( f t )
     The biokinetic constants are determined by conducting  laboratory  or  pilot
plant studies.  After the biokinetic constants are determined,  the  required
volume of aeration tank or the required surface area  for  a  biological  tower  or
rotating biological contactor can be determined for any flow  rate,  influent
concentration of BOD, COD, TOC, or specific organic,  and  a  required effluent
concentration of BOD, COD, TOC, or specific organic.


          10.1.2.4  Technology Selection/Evaluation


     Biological treatment has not been as widely used  in  hazardous  waste  site
remediation as activated carbon, filtration and precipitation/flocculation.
However, the process is well established for treating  a wide  variety of
organic contaminants.  Kincannon and Stove as reported by Canter  and Knox
(1985) have demonstrated the effectiveness of activated sludge  for  treating
priority pollutants.  The results shown in Table 10-6  indicate  that activated
sludge was effective for all groups of contaminants tested  except for
halogenated hydrocarbons.
                                     10-15
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                                  TABLE 10-6.

                     REMOVAL MECHANISMS OF TOXIC ORGANICS
          Compound
                                         Percept Treatment Achieved
Stripping
Sorption
Biological
Nitrogen Compounds
     Acrylonitrile
Phenols
     Phenol
     2,4-DNP
     2,4-DCP
     PGP
Aromatics
     1,2-DCB
     1,3-DCB
     Nitrobenzene
     Benzene
     Toluene
     Ethylbenzene
Halogenated Hydrocarbons
     Methylene Chloride
     1,2-DCE
     1,1,1-TCE
     1,1,2,2,-TCE
     1,2DCP
     TCE
     Chloroform
     Carbon Tetrachloride
Oxygenated Compounds
     Acroleiln
Polynuclear Aromatics
     Phenanthrene
     Napthalene
Phthalates
     Bis(2-Ethylhexyl)
Other
     Ehtyl Acetate
   21.7
    2.0
    5.1
    5.2

    8.0
   99.5
  100.0
   93.5
   99.9
   65.1
   19.0
   33.0
    1.0
                  0.58
   0.02
   0.19

  91.7
   0.50
   0.83
   1.19
   1.38
                                99.9
                                99.9
                                99.
                                95,
   97.3

   78.2

   97.8
   97.9
   94.9
   94.6
   33.8
   78.8
   64.9

   99.9

   98.2
   98.6

   76.9

   98.8
Source:  Canter and Knox, 1985 as cited by Kincannon and Stover, undated,
                                     10-16
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     Although biological  treatment  can  effectively  treat  a  wide  range  of
organics, it has several  drawbacks  for  hazardous waste  site applications.   The
reliability of the process can be adversely  affected by "shock"  loads  of
toxics.  Start-up time can be slow  if the  organisms need  to be  acclimated  to
the wastes and the detention time can be long  for complex wastes.   However,
the existence of cultures which have been  previously adapted to  hazardous
wastes can dramatically decrease start-up  and  detention time.

     There are a number of cleanup  contractors who  have used biological  treat-
ment as part of a mobile  treatment  system.   The high purity oxygen  treatment
process is well suited for mobile treatment  applications  because the high
oxygen efficiency enables use of smaller reactors,  shorter  detention time,  and
reduced power consumptions relative to  other activated  sludge processes.  A
hazard associated with the high purity  oxygen  process is  that the presence  of
low flash-point compounds can present a potential fire  hazard.   However, the
system is equipped with hydrocarbon analyzers  and control systems that
deactivate the system when dangerously  high  concentrations  of volatiles  are
detected (Ghassemi, Yu, and Quinlivan,  1981).  Loss of  volatile  organics from
other biological treatment processes can also  pose  some localized air
pollution and a health hazard to field  personnel.

     Rotating biological  contactors also have  advantages  for hazardous waste
site treatment.  The units are compact, and  they can handle large flow
variations and high organic shock loads, and they do not  require use of
aeration equipment.

     Sludge produced in biological waste treatment  may  be a hazardous  waste
itself due to the sorption and concentration of toxic and hazardous  compounds
contained in the wastewater.  If the sludge  is hazardous, it must be disposed
in a RCRA-approved manner.  If the  sludge  is not hazardous,  disposal should
conform with State sludge disposal guidelines.
     10.1.2.5  Costs
     Costs for various sizes of activated sludge units  are  presented  in  Table
10-7.  The costs for these units assume a detention time of 3 hours,  and use
of aeration basins, air supply equipment, piping, and a blower building.
Clarifier and recycle pumps are not included.  The basins are sized to the  50
percent recycle flow.  The influent biological oxygen demand (BOD) is assumed
to be no greater than 130 ppm and the effluent BOD is assumed to .be 40 ppm.

     The operation and maintenance costs assume that the hydraulic head  loss
through the aeration tank is negligible.  Sludge wasting and pumping  energy
are not included.

     Union Carbide manufactures a high purity oxygen activated sludge system
(UNOX) suitable for mobile system applications.  The mobile UNOX systems have
a hydraulic capacity of 5 to 40 gpm, are contained within 40 foot van
trailers, and include an external clarifier.  The oxygen required is  also


                                     10-17
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                                  TABLE 10-7.

   GENERAL COST DATA FOR VARIOUS SIZES OF ACTIVATED SLUDGE TREATMENT UNITS

Capacity (gpm)

70
140
350
694
Construction
Costs ($)*
78,500
85,600
107,000
160,000
O&M Costs ($/year)*

4,300
6,400
10,000
15,700
*Updated from 1978 to 1984 dollars using third quarter Marshall and Swift
Equipment Index.

Source:  Adapted from USEPA, 1980.
supplied by Union Carbide.  The customer is expected to provide installation
labor, operating manpower, analytical support, and utilities.  A typical
installation requires three to four days (Ghassemi, Yu, and Quinlivan,  1981).

     The mobile UNOX system can be either rented or purchased from the  Union
Carbide Corporation.  The estimated rental costs are as follows:
        $6,540 for the checkout and refurbishment of equipment to make  it
        operational

        $550/day for on-site service including engineering consultation on
        program planning and execution

        $9/day rental of equipment

        Transportation charges to get the equipment  from  the manufacturer to
        the site of operation and back again.
The purchase price for the UNOX mobile unit is between $260,000 and $330,000
(Ghassemi, Yu, and Quinlivan, 1981, updated using 1984 third quarter Marshall
Swift Index).
                                     10-18
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      10.1.3   Filtration
           10.1.3.1  General Description
     Filtration is a physical process  whereby suspended  solids  are removed
from solution by forcing the fluid  through a porous medium.   Granular media
filtration  is typically used for  treating aqueous waste  streams.   The filter
media consists of a bed of granular  particles (typically  sand or  sand with
anthracite  or coal) (Figure 10-2).   The  bed is contained  within a basin and is
supported by an underdrain system which  allows the filtered  liquid to be drawn
off while retaining the filter media in  place.  As water  laden  with suspended
solids passes through the bed of  filter  medium, the particles become trapped
on top of and within the bed.  This  either reduces the filtration rate at a
constant pressure or increases the  amount of pressure needed  to force the
water through the filter.  In order  to prevent plugging,  the  filter is
                                  FIGURE 10-2.
                             TYPICAL FILTRATION BED
                BACKWASH
                DRAIN
                                 HIGH HEAD
                                                       RAW FEED
BACKWASH
TROUGH r—
                                                   SINGLE OR
                                                   MULTIPLE LAYER
                                                   FILTER MEDIUM
                                                         BACKWASH
                                 UNDER DRAIN
                                                          EFFLUENT
               Source: Ghassemi, Yu, and Quinlivan, 1981
                                       10-19
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backflushed at high velocity  to dislodge  the  particles.   The  backwash  water
contains high concentrations  of solids  and  requires  further treatment
(De Renzo, 1978).


          10.1.3.2  Applications/Limitations


     Filters find economic application  in handling streams containing  less
than 100 to 200 mg/liter  suspended  solids,  depending  on  the required effluent
level.  Increased suspended solids  loading  will  reduce run lengths, and
require excessively frequent  backwash   (De  Renzo, 1978).  The suspended  solids
concentration of the  filtered liquid depends  a great  deal on  particle  size
distribution, but typically,  granular media filters  are  capable  of  producing  a
filtered liquid with  a  suspended  solids concentration as  low  as  1 to 10  mg/1.
Large flow variations will deleteriously  affect  effluent  quality.

     Often, granular media filters  are  preceded  by sedimentation to reduce  the
suspended solids load on  the  filter (De Renzo, 1978).  Granular  media
filtration is also frequently installed ahead of biological or activated
carbon treatment units  to reduce  the suspended solids load and in the  case  of
activated carbon to minimize  plugging of  the  carbon  columns (De  Renzo, 1978).

     The granular media filtration  process  is only marginally effective  in
treating colloidal size particles.  In  many cases, these  particles  can be made
larger by flocculation  although this will generally  reduce run lengths.  In
cases where it is not possible to flocculate  such particles (as  in  the case of
many oil/water emulsions), more advanced  techniques  such  as ultrafiltration
may be appropriate (De Renzo, 1978).


          10.1.3.3  Design Considerations


     The composition  and  sizing of  the  filtration bed is  an important  design
consideration.  Beds  of 4 feet or less  composed  of 0.5 mm sand and  0.9 mm
anthracite are frequently used.  However  deep-bed filters are also  available.
It is recommended that  pilot  plant  studies  be conducted  to determine optimum
size and combination of filter material.

     A filter bed can function properly only  if  the  backwashing  system
effectively cleans the material from the  filter.  Methods which  can be used
for backwashing include water backwash  only,  water backwash with auxiliary
surface water wash, water wash proceeded  by air  scour, and simultaneous  air
and water wash.

     The duration of  the backwash is about  20 min per cycle.   Backwash water,
which amounts to 1 to 5 percent of  the  total  flow, can be routed to a  primary
clarifier often via a storage vessel to allow flow equalization. Several
filters are used in parallel  to allow continuous processing during
backwashing; the backwash cycle usually is  automated.  Other  processes must be
sized to handle this  recycle  flow.

                                     10-20
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           10.1.3.4  Technology/Selection  Evaluation


     Filtration  is a reliable  and  effective means  of  removing  low levels of
solids from wastes provided  the  solids  content  does not vary greatly and the
filter is  backwashed at appropriate  intervals.

     Filtration  equipment  is relatively simple,  readily available in a wide
range of sizes,  and easy to  operate  and control.   Filtration is  also easily
integrated with  other treatment  steps.

     Because of  its small  space  requirements  and relatively simple  operation,
filtration is well suited  to mobile  treatment systems  as  well  as  on-site
construction.  There is extensive  experience  with  the  operation  of
granular-media filters at  hazardous  waste  sites.

     The EPA physical/chemical treatment  system which  has been in operation
for more than 9  years incorporates 3 "dual" media  (sand-anthracite)  filters
connected  in parallel in its treatment  train.   The filters are designed for a
maximum hydraulic loading  of 7 gpm/ft   or  67  gpm (Ghassemi, Yu,  and  Quinlivan,
1981).  There are also a number  of manufacturers of package plant systems
suitable for being trailer mounted and  a number of cleanup contractors who
operate mobile treatment systems which  include  granular media  filters as a
part of the treatment process.

     The most obvious maintenance  consideration with granular  media  filtration
is handling of the backwash.   The backwash will generally contain high
concentrations of contaminants and require subsequent  treatment.


           10.1.3.5  Costs
     Figure 10-3 shows construction and operating  costs  for  filtration
assuming a filtration rate of 5 gpm/ft .  A minimimum of 4 filters  are  assumed
to provide flexibility of operation.  Capital costs  include  filter  structures,
backwash and surface wash systems, media and polymer feeding.  Costs of
effluent filtering and pumping are not included.   Power  costs  are based on
each filter backwashing once per  12 hours (Gulp, Wesner  and  Gulp, 1978).

     The construction costs assume a filtration rate of  2 gpm/square foot and
76 in filter media (silica sand and anthracite coal mixture) depths inside  two
open-topped cylindrical steel tanks.  The construction costs also include
chemical feed systems (alum, soda ash, polymer, and chlorine), pumps,
pre-filter contact basin, a backwash storage basin, building,  and all
necessary piping.  The operation  and maintenance costs include all building
utilities, process utilities, routine maintenance  costs, and replacement of
filter media lost through normal backwash operations (Hansen, Gumerman,  and
Gulp, 1979).  The operation and maintenance costs  do not include treatment
chemicals because usage rates of  these chemicals would vary  considerably
                                     10-21
-------
                 FIGURE 10-3. COST OF EFFLUENT FILTRATION*
       0
       o
5,000
4,000
3,000
2,000
1,000
500
400
300
200
100













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o
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X
50 9.
40
20
in
                                                                Capital Costs  	
                                                                O&M Costs   	
                             5  6 7 8 9 10
                                              30 40 50
                               Plant Capacity, MOD
          •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
           (multiply value shown on this figure by 1.908)
          Source: Gulp, Wesner & Gulp, 1978
depending on  the wastestream characteristics.   Unit costs for treatment
chemicals are  presented  in Section 9.2.   Costs for various sizes of  package
neutralization,  precipitation, and filtration  plants are presented in  Table
10-8.
      10.1.4   Precipitation/Flocculation
           10.1.4.1  General Description


     Precipitation is a physiochemical  process whereby some  or  all of a
substance  in solution is transformed  into a solid phase.   It  is based on
alteration of the chemical equilibrium  relationships affecting  the solubility
of  inorganic species.  Removal of metals as hydroxides or  sulfides is the most
common  precipitation application  in  wastewater treatment.  Generally, lime or
sodium  sulfide is added to the wastewater in a rapid mixing  tank along with
flocculating agents (described below).   The wastewater flows  to a flocculation
chamber in which adequate mixing  and  retention time is provided for
agglomeration of precipitate  particles.  Agglomerated particles are separated
from the liquid phase by settling  in a  sedimentation chamber,  and/or by other
                                       10-22
-------
                                  TABLE  10-8.

            GENERAL COST DATA FOR VARIOUS  SIZES OF NEUTRALIZATION,
                     PRECIPITATION, AND  FILTRATION UNITS
Plant Capacity (gpm)            Construction               Operation  and
                                Cost ($)*                Maintenance  ($/year)*
4
8
40
80
140
225
280
560
78,770
89,610
126,520
179,300
253,610
293,670
396,960
619,940
20,730
21,390
26,550
47,960
56,700
57,560
61,860
92,000

*Updated from 1979 to 1984 dollars using third quarter Marshall and Swift
Index.

Source:  Adapted from Hansen, Gumerman, and Gulp, 1979.

physical processes such as filtration.  Figure 10-4 illustrates a typical
configuration for precipitation flocculation and sedimentation.

     Although precipitation of metals is governed by the solubility product of
ionic species, in actual practice, effluent concentrations equal to the
solubility product are rarely achieved.  Usually, the amount of lime added is
about three times the stoichiometric amount that would be added to reduce
solubility due to the common ion effect.  Figure 10-5 gives solubilities of
various metal hydroxides and sulfides at various pH levels.   The metal
sulfides have significantly lower solubility than their hydroxide counterparts
and more complete precipitation is achieved.  Metal sulfides are also  stable
over a broad pH range.  Many metal hydroxides, on the other hand, are  stable
only over a narrow pH range; metals reach a minimum solubility at a specific
pH, but further addition of lime causes the metal to become soluble again.
Therefore,  dosages of lime need to be accurately controlled.  This may be
particularly challenging when working with aqueous wastes from waste disposal
sites where wide variations in flow rates and quantities of metals are to be
expected.  The stabilities of metal carbonates are also quite dependent on pH.
                                     10-23
-------
                                    FIGURE 10-4.
    REPRESENTATIVE CONFIGURATION EMPLOYING PRECIPITATION, FLOCCULATION,
                               AND SEDIMENTATION
              PRECIPITATION
                                 FLOCCULATtON
   PRECIPITATING CHEMICALS—,

 FLOCCULATING AGENTS
 INLET LIQUID STREAM-
      AFTER THE ADDITION OF PRECIPITATING   BY SLOW AND GENTLE MIXING THE
      CHEMICALS THE PRECIPITATION REACTION  PRECIPITATED PARTICLES. AIDED BY
      COMMENCES TO FORM VERY SMALL PAR-   THE FLOCCULATING AGENTS, COLLIDE,
      TICLES CALLED PRECIPITATION NUCLEI.    AGGLOMERATE. AND GROW INTO LARGER
      THE FLOCCULATING AGENTS ALLOW THESE  SETTLEABLE PARTICLES
      PARTICLES TO AGGLOMERATE
-»•
RA
1
•~.irx_n
(
/

c
c
IP
J
^
ki
c
c
LP
j
^
HQ
P i

r>ID MIX TANK FLOCCULATION CHAMBER
   SEDIMENTATION
                                                                          OUTLET LIQUID
                                                                            STREAM
     SEDIMENTATION BASIN
THE SETTLEABLE PARTICLES PRODUCED
BY THE FLOCCULATION STEP ARE SETTLED,
COLLECTED AND PERIODICALLY REMOVED
     Source: De Renzo, 1978
      Flocculation  is used to  describe the  process by which small, unsettleable
particles suspended  in a liquid  medium are  made to agglomerate into  larger,
more  settleable  particles.  The  mechanisms  by which flocculation occurs
involve surface  chemistry and  particle change phenomena.   In simple  terms,
these various phenomena can be grouped into two sequential mechanisms  (Kiang
and Metry, 1982):

      •  chemically induced destabilization  of the requisite surface-related
         forces,  thus allowing  particles to  stick together  when they  touch and

      •  chemical bridging and  physical enmeshment between  the now nonrepelling
         particles,  allowing for  the formation of large  particles.

      Flocculation  involves three basic steps:

      •  addition of  flocculating agent to  the waste stream

      •  rapid mixing to disperse the flocculating agent

      •  slow and gently mixing to allow for contact between small particles.

      Typically, chemicals used to cause flocculation include alum, lime,
various iron salts  (ferric chloride, ferrous sulfate) and  organic flocculating
agents, often referred to as "polyelectrolytes."  These materials generally
consist of long-chain, water-soluble polymers such as polyacrylamides.   They
are used either  in  conjunction with the inorganic flocculants,  such  as  alum,
or as the primary  flocculating agent.   A polyelectrole may be termed cationic,
anionic or ampholytic depending  upon the type of ionizable groups; or nonionic
                                        10-24
-------
                               FIGURE 10-5.

           SOLUBILITY OF METAL HYDROXIDES AND SULFIDES
o>
S
•o
Q
"6

•I
       10°
      10-2
      10'
       ,-6
      10"8 '
     10'10 '
         0    1    2    3    4    5    6   7    8    9    10   11   12   13   14

                                        pH


 Source: Ghassemi, Yu, and Quinlivan, 1981
                                  10-25
-------
if it contains no ionizable groups.  The  range of physical/chemical
characteristics (e.g., density, viscosity,  toxicity  and molecular  weight)  of
the several thousand available polymers is  extremely broad.

     The inorganic flocculants, such as alum, lime or  iron  salts,  make  use of
precipitation reactions.  Alum (hydrated  aluminum sulfate)  is  typically added
to aqueous waste streams as a solution.   Upon mixing,  the slightly higher  pH
of the water causes the alum to hydrolyze and form fluffy,  gelatinous
precipitates of aluminum hydroxide.  These  precipitates, partially due  to
their large surface area, enmesh small particles and thereby create  larger
particles.  Lime and iron salts also have a tendency to form large fluffy
precipitates or "floe" particles.  Many precipitation  reactions, such as the
precipitation of metals from solution by  the addition  of sulfide ions,  do  not
readily form floe particles, but rather precipitate  as very fine and
relatively stable colloidal particles.  In  such cases, flocculating  agents
such as alum and/or polyelectrolytes must be added to  cause flocculation of
the metal sulfide precipitates (Canter and  Knox, 1985).

     Once suspended particles have been flocculated  into larger particles,
they usually can be removed from the liquid by sedimentation,  provided  that a
sufficient density difference exists between the suspended matter  and the
liquid.


          10.1.4.2  Applications/Limitat ions


     Precipitation is applicable to the removal of most metals  from  wastewater
including zinc, cadmium, chromium, copper,  fluoride, lead, manganese, and
mercury.  Also, certain anionic species can be removed by precipitation, such
as phosphate, sulfate, and  fluoride.

     Precipitation is useful for most aqueous hazardous waste  aqueous streams.
However, limitations may be imposed by certain physical or  chemical  character-
istics.  In some cases, organic compounds may form organometallic  complexes
with metals, which could inhibit precipitation.  Cyanide and other ions in the
wastewater may also complex with metals, making treatment by precipitation
less efficient.

     Flocculation is applicable to any aqueous waste stream where  particles
must be agglomerated into larger more settleable particles  prior to
sedimentation or other types of treatment.  There is no concentration limit
for precipitation or flocculation.  Highly  viscous waste streams will inhibit
settling of solids.

     In addition to being used to treat waste streams, precipitation can also
be used as an in-situ process to treat aqueous wastes  in surface impoundments.
In an in-situ application,  lime and flocculants are  added directly to the
lagoon, and mixing, flocculation, and sedimentation  are allowed to occur
within the lagoon.  In some cases, wind and pumping  action  can provide  the
energy for mixing.


                                     10-26
-------
          10.1.4.3  Design  Considerations


     Selection of the most  suitable  precipitate  or  flocculant  and  their
optimum dosages  is determined  through  laboratory jar  test  studies.   In
addition to determining  the appropriate  chemicals and optimum  chemical
dosages, other important parameters  which  need  to be  determined  as  part of the
overall design include (Canter  and Knox,  1985):

     •  most suitable chemical  addition  system
     •  optimum  pH requirement
     •  rapid mix requirements
     •  sludge production

     •  sludge flocculation, settling  and  dewatering  characteristics.
          10.1,4.4  Technology Selection/Evaluation


     Precipitation and flocculation are well established  technologies  and  the
operating parameters are well defined.  The processes  requires  only  chemical
pumps, metering devices, and mixing and settling  tanks.   The  equipment  is
readily available and easy to operate.  Precipitation  and  flocculation  can be
easily integrated into more complex treatment  systems.

     The performance and reliability of precipitation  and  flocculation  depends
greatly on the variability of the composition  of  the waste being  treated.
Chemical addition must be determined using laboratory  tests and must be
adjusted with compositional changes of the waste  being treated  or poor
performance will result.

     Precipitation is nonselective in that compounds other than those  targeted
may be removed.  Both precipitation and flocculation are  nondestructive and
generates a large volume of sludge which must  be  disposed.

     Precipitation and flocculation poses minimal  safety  and  health  hazards to
field workers.  The entire system is operated  at  near  ambient conditions,
eliminating the danger of high pressure/high temperature  operation with other
systems.  While the chemicals employed are often  skin  irritants,  they  can
easily be handled in a safe manner.


               10.1.4.5  Costs
     Table 10-9 shows a breakdown of costs for the 40 gpm  sulfex heavy metal
removal system illustrated in Figure 10-6.

                                     10-27
-------
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ui
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m

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                                                     10-28
-------
                   TABLE  10-9.  1985  CAPITAL COSTS* FOR SULFEX
                         HEAVY  METAL PRECIPITATION SYSTEM
          Selling Price

          Equipment                                                  Price

1.  Precipitator with  clear well,  centrifuge
    for dewatering,chemical feeds  and
    agitators, and engineering  drawings                            $68,768

2.  Filter with transfer  pump and  engineering
    drawings                                                         7,623

3.  Neutralization systsem including agitators,
    chemical  feeds, pH controls, sump  pump,  and
    engineering drawings                                            86,126

    Total selling price                                           $162,517

    Installation Cost  (estimated by
    outside contractor)                                            $66,657

                                            TOTAL                 $229,174
*Costs were updated to $1985 using the  1983  and  1985  ENR  Construction  Cost
 Index.

Source:  Metal Finisher's Foundation, 1977

                                                                          2
     The precipitator is sized to operate at  a surface  rate  of  1.6 gpm/ft  and
the filter at a surface rate of 3.2 gpm/ft  .  Chemical  costs  for  the Sulfex
process and a hydroxide precipitation process are  shown in Table  10-10.   These
costs were estimated for treament of an  influent containing 4 mg/1 Cu,  Cd,
Cr  , Ni, and Zn at pH 6.0.

     Figure 10-7 shows capital and operating  costs  for  a  flocculation  system
including chemical storage, chemical feeding  and rapid  mix.   A  polymer  dosage
of 1 mg/1 at 0.25 percent solution is assumed.  Construction  costs also
include piping and building to house the feeding equipment and  bag storage.

     Construction costs include:  Piping and building to  house  the feeding
equipment and bag storage.  1 Mgal/d plant size and smaller use manual  feed
procedures.  2 systems of tanks and feeders  are included.  10 Mgal/d plant
size includes cost of feeders and mixing tanks, one day tank  and  2 solution
feeders.  100 Mgal/d plant size includes costs for  4  feeders  and mixing tanks,
2 holding tanks and 10 solution feeders.  The rapid mix tank  is concrete,

                                     10-29
-------
                 TABLE 10-10.  COMPARISON OF CHEMICAL COSTS* OF
                  HYDROXIDE AND SULFIDE PRECIPITATION PROCESSES
               (1) Hydroxide Process
        Eff. Qyal.
Chemical
Dosage
Cost
Cu
Cd
Cr
Ni
Zn
Cu
Cd
Cr
Ni
Zn

(mg/1)
pH 7.5 pH
0.1 <0.
3.8 <0.
<0.5 <0.
2.3 <0.
1.3 <0.
(2)
Eff. Qual.
(mg/1)
pH 8.5
0.01
0.1
<0.05
0.05
0.01

10
1 CA(OH)2
1 Polymer
1 2 4
1
Sulfex Process
Chemical
71% NaHS
FeSO. . 7H_0
Polymer
Ca(OH)2

lb/1000 gal.
pH 7.5 pH 10
0.33 0.92
0.03 0.03
0.61

Dosage
lb/1000 gal.
pH 8.5
0.09
0.77
0.03
1.13

(if/1000 gal.
i/lb pH 7.5 pH 10
3.16 1.05 2.99
105.4 3.16 4.22
8.8 - 5.45

Total 4.21 12.66
Cost
/1000 gal.
.lb pH 8,5
19.77 1.76
3.95 2.99
105.4 3.16
3.16 3.51
Total 11.42

*Costs were updated to $1985 using the 1977 and 1985 ENR Construction Cost
 Index.

Source:   Metal Finisher's Foundation, 1977
                                     10-30
-------
              FIGURE 10-7. POLYMER ADDITION  COSTS*
IO
s ot
Millions of Dot
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:• CONSTRUCTION COST:














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                  0.1
                  - 3
                               10            10
                             WMMwlt* Flow. Mg«l/d
                                                        100
                OOOI
                  01
                               10           10
                             Wastew*Mr Flow. Mgal/d
                                                         OOOl
                                                         Jooooi
•Costs can be updated to $1966 using ENR Construction Cost Indices for 1902 and 1986
 (multiply value shown on this figure by 1.303)
    Source: USEPA, 1982a
                                  10-31
-------
equipped with stainless steel mixer and handrails.   0.1 Mgal/d  plant  size:   no
separate building is required.  Manual operation of  feeder, mix tank  solution
feeder and holding tank.


     10.1.5  Sedimentation Technology


          10.1.5.1  General Description


     Sedimentation is a process that relies upon gravity  to remove  suspended
solids in an aqueous waste stream.  The fundamentals of a  sedimentation
process includes (Kiang and Metry, 1982):

     •  A basin or container of sufficient size to maintain the liquid to be
        treated in a relatively quiescent state for  a  specified period of time

     •  A means of directing the liquid to be  treated  into the  above  basin  in
        a manner conducive to settling

     •  A means of physically removing the settled particles  from the liquid
        (or liquid from the settled particles).

     Sedimentation can be carried out as either a batch or continuous process
in lined impoundments, conventional settling basins, clarifiers, and  high rate
gravity settlers.  Modified aboveground swimming pools have been used many
times for sedimentation in temporary, short-term treatment systems  at
hazardous waste sites.  Figure 10-8 illustrates three  different design
configurations for sedimentation.  In sedimentation  ponds  the liquid  is merely
decanted as the particles accumulate on the bottom of  the  pond. Backhoes,
draglines, or siphons are used periodically to remove  settled solids.

     Sedimentation basins and clarifiers usually employ a  built-in  solids
collection and removal devices such as a sludge scrapper and  draw-off
mechanism.  Sedimentation basins are general rectaggular,  usually employ a
belt-like collection mechanism, and are mainly used  for removal of  truly
settleable particles from liquid.

     Clarifiers are usually circular and are used in applications involving
precipitation and flocculation as well as sedimentation.  Many  clarifiers are
equipped with separate zones for chemical mixing and precipitation,
floculation, and sedimentation (Kiang and Metry, 1982).


          10.1.5.2  Applications/Limitations


     Sedimentation is commonly applied to aqueous wastes with high  suspended
solid loadings.  This may include surface run-off, collected  leachate or
landfill toe seepage, dredge slurries, and effluents from biological  treatment
and precipitation/flocculation.  Sedimentation is also required as  a

                                     10-32
-------
                                      FIGURE 10-8.
                  REPRESENTATIVE TYPES OF SEDIMENTATION
  Setting Pond

        Inlet Liquid
                                                                    Overflow Discharge Weir
                                                                    Accumulated Settled Particles
                                                              Periodically Removed by Machinical Shovel
  Sedimentation Basin

          Inlet Zone
  Inlet Liquid
Settled Particles Collected
and Periodically Removed
                                     Baffles to Maintain
                                   "Quiescent Conditions
                                                                       Outlet Zone
                                                                           Outlet Liquid
Belt-Type Solids Collection Mechanism
  Circular Clarifier
                                                     Circular Baffle

Inlet Zone "
— \
TTTTX;
^<^>-,.


—^
'
\ .
«•
/ !
/ — L_
s
/ Liquid
/ Flow
-'TTTT-
, ,. , -^-*^***
Annular Overflow V
Outlet Liquid
— Settling Partic
          Settling Zone,
          Revolving Collection
              Mechanism
                          Settled Particles T        Collected and Periodically Removed
                                          i Sludge Drawoff
Source: De Renzo, 1978
                                          10-33
-------
pretreatment step for many chemical processes, including carbon adsorption,
ion exchange, stripping, reverse osmosis and  filtration.

     This technology is applicable to the removal of suspended solids heavier
than water.  Suspended oil droplets or oil-soaked particles may not  settle out
and may have to be removed by some other means.  Some sedimentation  units are
fitted with skimmers to remove oil and grease that  float to the water surface.
However, these would not be effective in removing emulsified oils.


          10.1.5.3  Design Consideration


     Sedimentation is frequently considered in terms of ideal setting.   The
ideal setting theory results in the following equation for surface loading or
overflow rate .

                                    V  -2
     where:  V  = setting velocity
             Q  = flow through the basin
             A = surface area of the basin

Sedimentation basin loadings (Q/A) are often expressed in terms of  gallons  per
day per square foot.  Thus under ideal settling conditions, sedimentation is
independent of basin depth and detention time, and depends only on  the  flow
rate, basin surface area and properties of the particle.

     However sedimentation does not perform according to ideal settling
conditions since settling is affected by such conditions as turbulence,  and
bottom scour.  Therefore removal of particles is dependent on basin depth,  and
detention time as well as flow rate surface area and particle size.   The
performance of a sedimentation basin on a suspension of discrete  particles  can
be calculated, but  it is not possible to calculate sedimentation  basin
performance for a suspension of flocculating particles, such as a wastewater,
because settling velocities change continually.  Laboratory settling tests,
however, may be performed to predict sedimentation basin performance.


             10.1.5.4  Technology Selection/Evaluation


     Sedimentation  provides a reliable means to remove suspended  matter from  a
waste stream, provided the suspended matter is settleable and the treatment
process including the use of flocclants/coagulants has been appropriately
designed from laboratory settling tests.  Most clarifiers are capable of
removing 90 to 99 percent of the suspended solids.
                                      10-34
-------
      Sedimentation employs  readily available  equipment and  is  relatively easy
to operate.   The process  is  versatile in that  it  can be applied  to almost any
liquid waste stream containing suspended solids.   It can also  be easily inte-
grated into  a more complex  treatment system as  a  pre- or post-treatment
method.   Sedimentation  is nonselective and nondestructive,  resulting in a
large volume of potentially  contaminated sludge that may require further
treatment  and disposal.
              10.1.5.5  Costs
     The  cost  of a system which includes chemical  clarification,  rapid mixing,
flocculation with alum and  polymer and sedimentation is shown  in  Figure 10-9.
The cost  estimate assumed alum and polymer dosages of 200 mg/1  and 1 mg/1
respectively,  and a flow rate  to the clarifier  of  800 gpd/ft  .  The costs of
chemical  sludge proceessing  and disposal are  not  included in the  capital
costs. O&M  costs include cost  of chemical purchase (Gulp, Wesner  and Gulp,
1978).

            FIGURE 10-9. COST OF CHEMICAL CLARIFICATION WITH ALUM*
          O
          o
          .1
          Q.
          (3
             5,000
             4,000

             3,000


             2,000
             1,000
              500
              400

              300


              200
              100
                                                                100
  O
50

40
30


20
°<*
                            3  4 5 6789 10
                                              20   30 40 50
                                                              100
                                                                10
              Capital Costs
              0&M Costs
                                   Plant Capacity, MGD
           •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
           (multiply value shown on this figure by 1.908)
           Source: Gulp, Wesner Ct Gulp, 1978
                                       10-35
-------
     10.1.6  Ion Exchange and Sorptive Resins


             10.1.6.1  General Description


     Ion exchange is a process whereby the  toxic  ions  are  removed  from  the
aqueous phase by being exchanged with relatively  harmless  ions  held  by  the  ion
exchange material.  Modern ion exchange resins  are  primarily  synthetic  organic
materials containing ionic functional groups to which  exchangeable ions are
attached.  These synthetic resins are structurally  stable  (that  is,  can
tolerate a range of temperature and pH conditions), exhibit a high exchange
capacity, and can be tailored to show selectivity towards  specific ions.
Exchangers with negatively-charged sites are cation exchangers  because  they
take up positively charged ions.  Anion exchangers have positively charged
sites and, consequently, take up negative ions.   The exchange reaction  is
reversible and concentration dependent, and it  is possible to regenerate the
exchange resins for reuse.  Sorptive (macroporous)  resins  are also available
for removal of organics and the removal mechanism is one of sorption rather
than ion exchange (Ghassemi, Yu, and Quinlivan, 1981).


             10.1.6.2  Applications/Limitat ions


     Ion exchange is used to remove a broad range of ionic species from water
including:

     •  All metallic elements when present  as soluble  species,  either anionic
        or cationic

     •  Inorganic anions such as halides, sulfates, nitrates, cyanides, etc.

     •  Organic acids such as carboxylics,  sulfonics,  and  some  phenols, at  a
        pH sufficiently alkaline to give the ions

     •  Organic amines when the solution acidity  is sufficiently acid to form
        the corresponding acid salt (De Renzo,  1978).

Sorptive resins can remove a wide range of  polar  and non-polar  organics.

     A practical upper concentration limit  for  ion exchange is  about 2,500  to
4,000 mg/1.  A higher concentration results in  rapid exhaustion of the  resin
and inordinately high regeneration costs.   Suspended solids in  the feed stream
should be less than 50 mg/1 to prevent plugging the resins, and waste streams
must be free of oxidants (De Renzo, 1978).
                                     10-36
-------
          10.1.6.3  Design Considerations


     Specific ion exchange and sorptive resins systems must be designed on a
case-by-case basis.  It is useful to note that although there are three major
operating models (fixed bed cocurrent, fixed bed countercurrent, and
continuous countercurrent), fixed bed countercurrent systems are most widely
used.  Figure 10-10 illustrates the fixed bed countercurrent and continuous
countercurrent systems.  The continuous countercurrent system is suitable for
high flows.  Complete removal of cations and anions ("demineralization") can
be accomplished by using the hydrogen form of a cation exchange resin and the
hydroxide form of an anion exchange resin.  For removal of organics as well as
inorganics, a combination adsorptive/demineralization system, can be used.  In
this system, lead beds would carry sorptive resins which would act as organic
scavengers, and the end beds would contain anion and cation exchange resins.
By carrying different types of adsorptive resins (e.g., polar and non-polar),
a broad spectrum of organics could be removed (Ghassemi, Yu, and Quinlivan,
1981).
          10.1.6.4  Technology Selection/Evaluation


     Ion exchange is a well established technology for removal of heavy metals
and hazardous anions from dilute solutions.  Ion exchange can be expected to
perform well for these applications when fed wastes of variable composition,
provided the system's effluent is continually monitored to determine when
resin bed exhaustion has occurred.  However, as mentioned previously, the
reliability of ion exchange is markedly affected by the presence of suspended
solids.  Use of sorptive resins is relatively new and reliability under
various conditions is not as well known.

     Ion exchange systems are commercially available from a number of vendors.
The units are relatively compact and are not energy intensive. Start-up or
shut-down can be accomplished easily and quickly (Ghassemi, Yu, and Quinlivan,
1981).  These features allow for convenient use of ion exchange and sorptive
resin systems in mobile treatment systems.

     Although exchange columns can be operated manually or automatically,
manual operation is better suited for hazardous waste site applications
because of the diversity of wastes encountered; with manual operation, the
operator can decide when to stop the service cycle and begin the backwash
cycle.  However, this requires use of a skilled operator familiar with the
process (Ghassemi, Yu, and Quinlivan, 1981).

     Use of several exchange columns at a site can provide considerable
flexibility.  As described previously, various resin types can be used to
remove anions, cations, and organics.  Various columns can be arranged in
series to increase service-life between regeneratation of the lead bed or in
parallel for maximum hydraulic capacity.  The piping arrangement would allow
for one or more beds to be taken out for regeneration while the remaining
columns would remain in service. (Ghassemi, Yu, Quinlivan, 1981).

                                     10-37
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                                  FIGURE 10-10.
  PERTINENT FEATURES  OF  ION EXCHANGE  SYSTEMS
  Types
                       Counlercurrenl Fixed Bed
                                    HtOtNtHAllON
                                                           Continuous Counlercuirenl
                                                        HtGfNEFUTIOI
Description
of Process
Indications
(or Use
Advantages
Disadvantages
Regeneralion Hows opposite in direction
to Influent Backwash (in regeneration)
does not occur on ovary cycle to pre-
serve resin stage heights Resin bed is
locked in place during regeneration

Handles high loads at moderate Ihrupul
or low loads at high thruput (GPM x TDS
or GPM x PPM removal = 40,000  or
more) Where effluent quality must be
relatively constant, regeneration cost Is
relatively critical, disposal  of  single
batch waste volume no problem
                  Moderate capital cost Can be operated
                  with  periodic  attention   Moderate
                  regeneration cost  Lesser  volume of
                  waste due to less frequent backwash
                  Consistent effluent quality
                  Increased conlrols and instrumentation,
                  higher cost  Requires mechanism lo lock
                  resin bed Large single batches of waste
                  disposal  Moderate water consmption
                  thru dilution and waste Requires sub-
                  stantial llooi space
Multi-stage counlercurrent movement of
resin in closed loop providing simul-
taneous treatment, regeneration, back-
wash and rinse Operation is onty Inter-
rupted for momentary resin pulse

Highloads  with high thrupuls  (GPM x
TDS 01 GPM x PPM removal  = 40,000 or
more) Where constant effluent quality Is
essential, regeneration  costs  critical,
total waste volume requires small, con-
centrated stream  lo be controllable
Where loss of product thru dilution and
waste must be  mimmi/ed Where avail-
able floor space is limited

Lowest regeneration cost Lowest resin
Inventory Consistent effluent  quality
Highest  Ihrupul to  floor space  Large
capacity units  factory  preassernblud
Concentrated low volume waste stream
Can handle strong chemical solutions
and slurry  Fully automatic opeiation

Requires automatic conlrols and inslru
mentation,  highei capital cost  Moie
headroom required
Source: Chemical Seperations Corporation
                                       10-38
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     Consideration must be given  to disposal of  contaminated  ion exchange
regeneration solution.  In addition to  proper  disposal,  another  important
operational consideration is the  selection of  regeneration  chemicals.   Caution
must be exercised in making this  selection to  ensure  the compatibility of the
regenerating chemical with the waste being treated.   For example,  the  use of
nitric acid to regenerate an ion  exchange column containing ammonium ions
results in the formation of ammonium nitrate,  a  potentially explosive
compound.

          10.1.6.5  Costs
     Costs for various sizes of ion exchange units  are  presented  in  Table
10-11. The construction costs assume fabricated  steel contact vessels  with
baked phenolic linings, a resin depth of 6 feet, housing  for the  columns, and
all piping and backwash facilities.

     Operation and maintenance costs include electricity  for backwashing
(after 150 bed volumes have been treated) and periodic  repair and  replacement
costs.  Costs for regenerant chemicals are not included because they vary
depending on the types and concentrations of target chemicals to  be  removed
from the wastewater.
                                 TABLE 10-11.

            GENERAL COST DATA FOR VARIOUS SIZES OF EXCHANGE UNITS
Plant Ccpacity (gpm)            Construction               Operation  and
                                Cost ($)*                Maintenance  Costs
                                                             ($/year)*
50
195
305
438
597
84,105
116,200
134,770
154,000
180,270
14,530
21,260
24,280
27,590
31,531
*Updated from 1979 to 1984 dollars using third quarter Marshall and Swift
 Index.

Source:   Adapted from Hansen, Gumerman, and Gulp, 1979.
                                     10-39
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     10.1.7  Reverse Osmosis
          10.1.7.1  General Description
     Osmosis is the spontaneous  flow of solvent  (e.g., water)  from  a  dilute
solution through a semipermeable membrane (impurities or  solute  permeates  at  a
much slower rate) to a more concentrated solution.  Reverse  osmosis is  the
application of sufficient pressure to the concentrated solution  to  overcome
the osmotic pressure and force the net flow of water through the membrane
toward the dilute phase.  This allows the concentration of solute (impurities)
to be built up in a circulating  system on one side of the membrane  while
relatively pure water is transported through the membrane.   Ions and  small
molecules in true solution can be separated from water by this technique.

     The basic components of a reverse osmosis unit are the  membrane, a
membrane support structure, a containing vessel, and a high  pressure  pump.
The membrane and membrane support structure are  the most  critical elements.


          10.1.7.2  Applications/Limitations


     Reverse osmosis (RO) is used to reduce the  concentrations of dissolved
solids, both organic and inorganic.  In treatment of hazardous waste
contaminated streams, use of reverse osmosis would be primarily  limited to
polishing low flow streams containing highly toxic contaminants.  In  general,
good removal can be expected for high molecular weight organics  and charged
anions and cations.  Multivalent ions are treated more effectively  than are
univalent ions.  Recent advances in membrane technology have made it  possible
to remove such low moelcular weight organics as  alcohols, ketones,  amines, and
aldehydes (Gooding, 1985).  Table 10-12 shows removal results  obtained  during
testing of a mobile RO unit using two favorable membrane  materials  (Whittaker,
1984).

     RO Units are subject to chemical attack, fouling, and plugging.
Pretreatment requirements can be extensive.  Wastewater must be  pretreated to
remove oxidizing materials such  as iron and maganese salts,  to filter out
particulates, adjust pH to a range of 4.0 to 7.5, and to  remove  oil,  grease,
and other film forms (De Renzo,  1978).  The growth of slimy  biomass on  the
membrane surface or the presence of organic macromolecules may also foul the
membrane.  This organic fouling  can be minimized by prechlorination,  addition
of biocides and/or pretreatment  with activated carbon (Ghassemi, Yu,  and
Quinlivan, 1981).


          10.1.7.3  Design Considerations

     The most critical design consideration applicable to reverse osmosis
technology is the design of the  semipermeable membrane.   In  addition  to
                                     10-40
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                                 TABLE  10-12.




            RESULTS OF PILOT  SCALE TESTING  OF A  REVERSE  OSMOSIS  UNIT

Percent removed in permeate
Chemical
Dichloromethane
Acetone
1 , 1-Dichloroethene
Tetrahydro f uran
Diethyl ether
Chloroform
1 , 2-Dichlorethane
1,1,1-Trichloro-
ethane
Trichloroethene
Benzene
Bromoform
Hexane
Feed
Concentration
(ppb)
406
110
34
17,890
210
270X
99
659

241
539
121
^
Percent
Concentrated
in Concentrate
203
355
795
467
439
567
415
651

346
491
633
704
Polyether-
polysul phone
membrane
58
84
99
98
97
98
92
99.8

99
99
99.1
99.8
Polyester/
amide poly-
sul phone
membrane
52
76
95
89
89
92
85
97

92
99
98
97

1.   no standard available; concentration estimated.




Source:   Whittaker, 1984
                                     10-41
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allowing the achievement of the required degree of separation at an economic
flux level under ideal conditions, the membrane must be incorporated in an
operating system which satisfies- these practical requirements (Conway and
Ross, 1980):

     o  Minimum concentration polarization, ie., ratio of impurity
        concentration at the membrane surface to that in the bulk stream

     o  High packing density, i.e., membrane surface area per unit volume of
        the pressure module

     o  Ability to handle any particulate impurities (by proliferation if
        necessary)

     o  Adequate support for the membrane and other physical features such as
        effectiveness of seals, ease of membrane replacement, and ease of
        cleanning.

     Membranes are usually fabricated in flat sheets or tubular forms and are
assembled into modules.  The most common materials used are cellulose acetate
and other polymers such as polyamides and polyether-polysulphone.  There are
three basic module designs: tubular, hollow fiber, and spiral wound.  These
are illustrated in Figure 10-11.  Each type of membrane module has its own
advantages and limitations.  The tubular module provides the largest flow
channel and allows for turbulent fluid flow regime; thus, it is least
susceptible to plugging caused by suspended solids and has the highest flux.
However, because of its small area/volume ratio the total product recovered
per module is small.  The cost of a tubular module is approximately five times
that for the other modules for an equivalent rate of water recovery, and the
total space requirement is about three to five times that for the spiral wound
system (Ghassemi, Yu and Quinlivan, 1981).

     A hollow fiber membrane is constructed of polyamide polymers and
cellulose triacetate by Dupont and Dow, respectively.  The polyamide membrane
permits a wider operating pH range than cellulose acetate, which is commonly
used for the construction of spiral wound and tubular membranes.  The flow
channel and the flux are about an order of magnitude lower than thee other
configurations.  This small flux, however, is compensated for by the large
surface area/volume ratio, with the total product water per module being close
to that obtainable with spiral wound modules.  However, because of the small
size of the channels (about 0.004 in.) and the laminar fluid flow regime
within the channels, this module is susceptible to plugging and may require
extensive pretreatment to protect the membrane (Ghassemi, Yu and Quinlivan,
1981).

     The spiral wound module consists of an envelope of flat sheet membranes
rolled around a permeate collector tube.  This configuration provides for a
higher flux and greater resistance to fouling than the hollow fiber modules;
it is also  less expensive and occupies less space than a tubular module
(Ghassemi, Yu and Quinlivan, 1981).
                                     10-42
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                FIGURE 10-11. MEMBRANE MODULE CONFIGURATIONS
                              A. TUBULAR MEMBRANE
                     CASING
                     MEMBRANE
                                                    WATER
                                                    FLOW
                            b.  SPIRAL-WOUND MODULE
               ROLL TO
               ASSEMBLE
                                       FEED FLOW
                         V
                        PERMEATE FLOW
                        (AFTER PASSAGE
                        THROUGH MEMBRANE
      FEED SIDE
      SPACER
       X
PERMEATE OUT
PERMEATE SIDE BACKING
MATERIAL WITH MEMBRANE ON
EACH SIDE AND GLUED AROUND  \
EDGES AND TO CENTER TUBE
                             c. HOLLOW-FIBER MODULE
                  CONCENTRATE
                  OUTLET
                              FLOW
                             SCREEN
                                                OPEN END
                                                OF FIBERS
 EPOXY
TUBE SHEET
                                                               POROUS
                                                              BACK-UP DISC
                                                                     SNAP RING
       "O" RING
        SEAL
             END PLATE
                                                                     PERMEATE
                         FIBER
                                  SHELL
                                          POROUS FEED
                                          DISTRIBUTOR
                                             TUBE
                                                    "O" RING  END PLATE
                                                      SEAL
Source: Ghassemi, Yu ft Quinlivan, 1981
                                       10-43
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          10.1.7.4  Technology Selection/Evaluation


     Reverse osmosis is an effective treatment technology for removal of
dissolved solids presuming appropriate pretreatment has been performed  for
suspended solids removal, pH adjustments, and removal of oxidizers, oil,  and
grease.  Because the process is so susceptible to fouling and plugging,
on-line monitors may be required to monitor pH, suspended solids, etc.  on a
continuous basis.  Reverse osmosis has not been widely used for treatment of
hazardous wastes.

     Reverse osmosis will not reliably treat wastes with a high organic
content, as the membrane may dissolve in the waste.  Lower levels of organic
compounds may also be detrimental to the unit's reliability, as biological
growth may form on a membrane fed an influent containing biodegradable
organics.

     The fact that RO units can be operated in series or in parallel provides
some flexibility in dealing with increased flow rates or concentration  of
dissolved species.

     Memtek Corporation of Ontario, Canada has developed a mobile reverse
osmosis unit for Environment Canada.  The unit, which is capable of handling
low flows of about 10 gpm is currently being tested for various types of
spills (Whittaker, 1984).

     The volume of the reject generated by reverse osmosis is about 10  to
25 percent of the feed volume.  Provisions must be made to treat this
potentially hazardous waste.
          10.1.7.5  Costs
     Costs for various sizes of reverse osmosis units are presented  in Table
10-13.  The construction costs include housing, tanks, piping, membranes,  flow
meters, cartridge filters, acid and polyphosphate  feed equipment,  and cleanup
equipment.  These costs are based on influent total dissolved solids concen-
trations of less than 10,000 ppm.

     The operation and maintenance costs include electricity for  the high
pressure feed pumps (450 psi operating pressure), building utilities, routine
periodic repair, routine cleaning, and membrane replacement every 3 years.
Operation and maintenance costs do not include costs for pretreatment
chemicals due to extreme usage rate variability between plants.
                                     10-44
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                                  TABLE 10-13.

          GENERAL COST DATA FOR VARIOUS SIZES OF REVERSE OSMOSIS UNITS

Plant Capacity (gpra)
1.74
7
70
700
Construction
Costs ($)*
17,070
33,280
171,820
1,014,600
O&M Costs
($/year)
7,580
12,070
40,829
249,930

*Updated  from  1979  to  1984  dollars  using third quarter Marshall and Swift
  Index.

Source:   Adapted  from  dansen,  Gumertnan,  and  Gulp,  1979.
     The RO unit  being  tested by  Environment  Canada can handle flow up to
 11,000 gpd and  costs  approximately $60,000.   Membranes vary considerably in
 cost.  The Toray  and  DSI membranes discussed  in Table 10-12,  for example, cost
 $360 and $915,  respectively (Whittaker  et  al.,  1985).


     10.1.8  Neutralization
           10.1.8.1  General  Description


     Neutralization consists  of  adding acid  or  base to a waste in order to
adjust its pH.  The most  common  system for neutralizing acidic or basic waste
streams utilizes a multiple  compartmental basin usually constructed of
concrete.  This basin  is  lined with  acid brick  or  coated with a material
resistant  to the expected  environment.

     In order to reduce the  required  volume  of  the neutralization basin,
mixers are installed in each  compartment to  provide more intimate contact
between the waste and  neutralizing reagents,  thus  speeding up reaction time.
Stainless  steel plates mounted on the floor  of  the pit and directly below the
mixers will reduce corrosion  damage  to the structure.   Basin inlets are
baffled to provide for flow distribution, while effluent baffles can help to
prevent foam from being carried  over  into the receiving stream (Conway and
Ross, 1980).
                                      10-45
-------
     In some cases, neutralization may be accomplished  in a discharge  sewer.


          10.1.8.2  Application/Limitation


     Neutralization can be applied to any wastestream or wastewater requiring
pH control.  It is commonly used prior to biological treatment,  since  bacteria
are sensitive to rapid pH changes and values outside a  pH range  of 6 to 9.
Similarly, aquatic ecosystems are pH sensitive, therefore neutralization  of
wastewater is required prior to discharge to a receiving water body.   In  the
case where hazardous wastes are hazardous because of corrosivity, neutraliza-
tion may be required prior to acceptance for disposal.  It is also used as a
pretreatment for several chemical treatment technologies, including carbon
adsorption, ion exchange, air stripping, wet air oxidation, and  chemical
oxidation/reduction processes.  A pH adjustment is also dictated in several
other situations, including protection of construction materials, breaking of
emulsions, insolubilization of certain organic materials, and control  of
chemical reaction rates (e.g., chlorination) (Conway and Ross, 1980).


          10.1.8.3  Design Considerations


     The choice of an acidic reagent for neutralization of an alkaline
wastewater is generally between sulfuric acid and hydrochloric acid.   Sulfuric
acid is usually used due to its lower cost.  Hydrochloric acid has the
advantage of soluble reaction end products.

     The selection of a caustic reagent is usually between sodium hydroxide
and various limes; ammonium hydroxide is occasionally used.  The factors  to be
considered in choosing the most suitable reagent include:  purchase cost,
neutralization capacity, reaction rate, storage and  feeding requirement,  and
neutralization products.

     Although sodium hydroxide costs much more than  the other materials,  it is
frequently used due to uniformity, ease of storage and  feeding,  rapid  reaction
rate, and soluble end products.  The lime materials  have the advantage of
relatively low cost.  This low material cost is at least partially offset by
increased capital and operating costs for the rather complex feeding and
reaction system required (Conway and Ross, 1980).

     While the rate of reaction between the completely  ionized sodium
hydroxide and a strong acid waste is virtually instantaneous, the reactions of
lime bases require considerable time for completion.  Reaction time can be
minimized by several approaches:  a relatively high  end point pH level,
efficient mixing, and slurry feeding as opposed to dry  feeding (Conway and
Ross, 1980).
                                     10-46
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          10.1.8.4  Technology Selection/Evaluation


     Neutralization is a relatively simple unit treatment process which can be
performed using readily available equipment.  Only storage and reaction tanks
with accessory agitators and delivery systems are required.  Because of the
corrosivity of the wastes and treatment reagents, appropriate  materials of
construction are needed to provide a reasonable service-life for equipment.
The process is reliable provided pH monitoring units are used.  The feed of
the neutralization agent may be regulated automatically by the pH monitoring
unit thereby ensuring effective neutralization and minizing worker contact
with corrosive neutralizing agents.

     Neutralization of hazardous wastes has the potential of producing air
emissions.  Acidification of streams containing certain salts, such as
sulfide, will produce toxic gases.  Feed tanks should be totally enclosed to
prevent escape of acid fumes.  Adequate mixing should be provided to disperse
the heat of reaction if wastes being treated are concentrated.  The process
should be controlled from a remote location if possible.
          10.1.8.5  Costs

     Capital costs for a neutralization system include costs for chemical
storage, chemical feeding and mixing.  These costs can be approximated using
Figure 10-7.

     10.1.9  Gravity Separation


          10.1.9.1  General Description


     Gravity separation is a purely physical phenomenon in which the oil is
permitted to separate from water in a conical tank.


          10.1.9.2  Applications/Limitations

     Gravity separators are primarily used to treat two-phased aqueous wastes.
A typical application would be separation of free gasoline or fuel oil from a
fuel contaminated aquifer.  Gravity separation has also been used to separate
PCS oils from contaminated groundwater.  For efficient separation, the
nonaqueous phase should have a significantly different specific gravity than
water and should be present as a nonemulsified substance.  Emulsion between
water and oil is common, and an emulsion breaking chemical must frequently be
added to the waste for efficient treatment.
                                     10-47
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          10.1.9.3  Design Considerations


     Gravity separators can take many shapes and arrangements, depending in
part on the characteristics of the waste.  The modern trend is to keep
separator design small and simple to reduce costs.  Typical design configura-
tions include:   horizontal cylindrical decanters, vertical cylindrical
decanters, and cone-bottomed settlers.

     Baffles are frequently installed to provide additional surface area,
which promotes oil droplet coalescence.  The cone-bottomed design is
particularly useful if heavy solids are to be settled out of the waste while
oil separation is proceeding.


          10.1.9.4  Technology Selection/Evaluation


     Gravity separation offers a straightforward, effective means of phase
separation provided the oil and water phases separate adequately within the
residence time of the tank.  Simple, readily available equipment can be used
and operational requirements are minimal.  If emulsion-breaking chemicals must
be added to promote oil-water separation, laboratory tests should be period-
ically conducted to ensure adequate dosing.

     Consideration must also be given to the disposal of the extracted waste
constituents collected.  For gravity separation processes, this material
consists of immiscible oil siphoned from the separator.


     10.1.10  Air Stripping


          10.1.10.1  General Description


     Air stripping is a mass transfer process in which volatile contaminants
in water or soil are transferred to gas.

     As shown in Figure 10-12, there are four basic equipment configurations
used to air strip liquids.

     Air stripping is frequently accomplished in a packed tower equipped with
an air blower.  The packed tower works on the principle of countercurrent
flow.  The water stream flows down through the packing while the air flows
upward, and is exhausted through the top.  Volatile, soluble components have
an affinity for the gas phase and tend to leave the aqueous stream for the gas
phase.  In the cross-flow  tower, water flows down through the packing as in
the countercurrent packed  column, however, the air is pulled across the water
flow path by a fan.  The coke tray aerator is a simple, low-maintenance
process requiring no blower.  The water being treated is allowed to trickle


                                     10-48
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              FIGURE 10-12. AIR STRIPPING EQUIPMENT CONFIGURATIONS
                   PACKED COLUMN
                INFLUENT-
                             DISTRIBUTOR
                                        INFLUENT
                           DIFFUSED AIR BASIN

                              AIR SUPPLY

                             :r£F
            SUPPORT
             PLATE
          br— INCOMING
        ,,. ^   *'"
  EFFLUENT!

COKE TRAY AERATOR
              RAW WATER
                INUTT-0
      DDDD
      noon
•SPLASH
APRONS
                                 •OUTLBT
                                                              •EFFLUENT
                                             CROSS-FLOW TOWER
                                                    AIR,OUTLET
                                         INLET
                                                       COLLECTION
                                                         BASIN
Source: Canter and Knox, 1985
 through several  layers  of  trays.   This produces a large  surface  area for gas
 transfer.  Diffused  aeration stripping and induced draft  stripping  use
 aeration basins  similar to standard wastewater treatment  aeration basins.
 Water flows through  the basin from top to bottom or from  one  side to another
 with the air dispersed  through diffusers at the bottom of the  basin.  The
 air-to-water ratio is significantly lower than in either  the  packed column or
 the cross-flow tower (Canter and  Knox, 1985).
           10.1.10.2  Applications/Limitations
      Air stripping  is used  to  remove volatile organics from  aqueous  waste-
 streams.  Generally components  with Henry's Law constants of greater than
 0.003 can be effectively  removed  by air stripping (Conway and  Ross,  1980).
 This includes such  components  as  1,1,1-trichloroethane, trichloroethylene,
 chlorobenzene, vinyl chloride,  and  dichloroethylene.  The feed  stream must be
 low in suspended solids and may require pH adjustment of hydrogen  sulfide,
 phenol, ammonia, and other  organic  acids or bases to reduce  solubility and
 improve transfer to the gas phase.   Stripping is often only  partially
 effective and must be followed  by another process such as biological treatment
 or carbon adsorption. Combined  use  of  air stripping and activated  carbon can
 be an effective way of removing contaminants from groundwater.   The  air
 stripper removes the more volatile  compounds not removed by  activated carbon
                                       10-49
-------
and reduces the organic load on the carbon, thus reducing  the  frequency  (and
expense) of carbon regeneration.

     The countercurrent packed tower has been the most widely  used  equipment
configuration for air stripping at hazardous waste sites.  The reason  for  this
are (Canter and Knox, 1985):

     (1)  It provides the most liquid interfacial area.

     (2)  High air-to-water volume ratios are possible due to  low air  pressure
          drop through the tower.

     (3)  Emission of stripped organics to the atmosphere  may  be environ-
          mentally unacceptable; however, a countercurrent tower is relatively
          small and can be readily connected to vapor recovery equipment.


     The major disadvantage of the packed column is the high energy cost.


          10.1.10.3  Design Considerations
     The design of a packed tower air stripper generally  involves a deter-
mination of the cross-sectional area of the column and  the height of  the
column packing.  The cross-sectional area of the column is determined  from
physical properties of the air flowing through the column, the  characteristics
of the packing and the air-to-water flow ratio.

     A key factor is the establishment of an acceptable air velocity.   A
general rule of thumb used for establishing the air velocity  is  that  an
acceptable air velocity is 60% of the air velocity at flooding.  Flooding is
the condition in which the air velocity is so high that it holds up the water
in the column to the point where the water becomes the  continuous phase rather
than the air.  If the air-to-water ratio is held constant, the  air velocity
determines the flooding condition.  For a selected air-to-water  ratio,  the
cross-sectional area is determined by dividing the air  flow rate by the air
velocity.  The selection of the design air-to-water ratio must  be based upon
experience or pilot-scale treatability studies.  Treatability studies  are
particularly important for developing design information  for  contaminated
ground water (Canter and Knox, 1985).
                                      10-50
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     The height of column packing may be determined by the following equation
(Canter and Knox, 1985):
          In
                            -(1-A) + A
where
                KLaC(l-A)(l-X)M

           Z = height of packing, ft.
           L = water velocity, Ib-mole/hr/ft
          X~ = influent concentration of pollutant in ground water, mole
               fraction
           .
               effluent concentration of pollution in ground water, mole
               fraction
         K a = mass transfer coefficient, gal./hr.
           C = molar density of water = 3.47 Ib-mole/ft
           H = Henry's law constant, mole fraction in air per mole fraction in
               water
           G = air velocity, Ib-mole/hr/f t
           A = L/HG
      (l-X)M = the average of one minus the equilibrium water concentration
               through the column
          Y, = influent concentration of pollutant in air, mole fraction

In most cases, the following assumption can be made :

(1) Y. = 0, there should be no pollutants in the influent air.

(2) (l-X)M = 1, the influent concentrations should be too small when converted
to mole fraction to shift this term significantly from 1.0.
The packing column height can then be determined by the simplified equation:

                 ^2_   (1-A) + A | L
          In  I   X
     Z = 	——	
                  TO, a C(l-A)
                            "]
     The mass transfer coefficient, Ka, is determined from pilot-scale
treatability studies, and is a function of type of compound being removed,
air-to-water ratio, groundwater temperature, type of packing and tower
geometry (Canter and Knox, 1985).

     Calgon Carbon Corporation maintains a computer modelling system which
determines the appropriate tower diameters, parking heights, air/water ratios
and tower packing for a particular aplication (Calgon Carbon Corp. 1983).
This system facilitates rapid mobilization of the packed tower equipment to a
site.
                                     10-51
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          10.1.10.4  Technology Selection/Evaluation


     In recent years, air  stripping has gained  increasing  use  for  the
effective removal of volatile organics from aqueous wastestreams.   It  has  been
used most cost-effectively  for treatment of low concentrations  of  volatiles or
as a pretreatment step prior to activated carbon.  Calgon  manufacturers  a
treatment system which combines air stripping and  activated  carbon.

     The equipment for air  stripping  is relatively simple, start-up  and
shut-down can be accomplished quickly, and the  modular  design  of packed  towers
makes air stripping well suited for hazardous waste site applications.

     An important factor in the consideration of whether to  utilize  air
stripping technology for the removal  of volatile contaminants  is the air
pollution implications of  air stripping.  The gas  stream generated during
treatment may require collection and  subsequent treatment  or incineration.


          10.1.10.5  Costs
     Packed tower air strippers have higher  removal  efficiencies  than induced-
draft systems, which are similar to diffused  aeration  systems.  However,  the
induced-draft system is lower  in capital  cost  and  requires  less energy to
operate than a packed-tower system.  Table  10-14 describes  the  installed  cost
of an induced-draft stripper manufactured and  marketed  by the Calgon Carbon
Corporation.  As shown in Table 10-14, the  installed cost of an induced-draft
stripper, capable of treating  700 gpm  and removing 75 percent of  the TCE
contamination, is about 31 percent  ($19,000 vs.  $61,300) of the cost of a
packed-tower capable of removing 95 percent  of the TCE.  Assuming that a  well
pump with a minimum discharge  head of  25  pisig is  required  to feed both units,
the packed-tower also uses an  additional  $5,100 per  year in electrical energy
for operation of the blower.

     In a typical treatment system, re-pumping of  the  treated water would be
required.  Adding the cost of  a sump,  flow  control,  and a pump, the overall
project cost for the induced-draft  system would be about one-half the cost of
the packed tower system (Calgon Carbon Corp.,  undated).


     10.1.11  Oxidation
           10.1.11.1  General Description


     Reduction-oxidation  (redox)  reactions  are  those  in which the oxidation-
 state of  at  least one  reactant  is  raised  while  that of  another is lowered.   In
                                      10-52
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                  TABLE 10-14.  AIR STRIPPING COST ESTIMATES
                 (Basis:  700 gpm; 1000 micrograms/liter TCE)

Induced-Draft
Stripper
(75% Removal)
Air Stripping Equipment
Stripper Assembly & Installation
Equipment Sub-total
Recharge Pump; Assembly and Controls
Found at ion/ Sump
Equipment Freight
Project Management
Project Contingency
Total
$15,000
4,000
$19,000
$16,000
18,000
2,000
10,000
7,000
$72,000
9
Packed-Tower
5-ft Diameter
(95% Removal)
$42,300
19,000
$61,300
$16,000
23,700
5,000
20,000
20,000
$146,000

Saigon Model No. 909B (8'0" x 9'1" x 9' 0").
2
 Tower is made of fiberglass reinforced plastic and contains 15 ft.  of 2-in.
 diameter polypropylene pall ring packing.
3
 Cost includes tower, packing, packing support, detnister, 4,000 cfm fan with
 10 hp motor, damper, piping valves, and ductwork.
4
 Sump 5"  x 5" x 8'  below grade concrete.

Source:  O'Brien and Stenzel, undated.
                                     10-53
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chemical oxidation, the oxidation state of the treated compound(s) is raised.
For example in the conversion of cyanide to cyanate under alkaline conditions
using permanganate, the oxidation state of the cyanide ion is raised as it
combines with an atom of oxygen to form cyanate.  This reaction can be
expressed as follows:

     2 NaCN + 2KMnO,  + KOH    2 K MNO,  + NaCNO + H_0

     Common commercially available oxidants include potassium permanganate,
hydrogen peroxide, calcium or sodium hypochlorite and chlorine gas.


          10.1.11.2  Applications/Limitations


     Chemical oxidation is used primarily for detoxification of cyanide and
for treatment of dilute waste streams containing oxidizable organics.  Among
the organics for which oxidative treatment has been reported are:  aldehyde,
mercaptans, phenols, benzidine, unsaturated acids and certain pesticides
(Kiang and Metry, 1982).

     Chemical oxidation can be an effective way of pretreating wastes prior to
biological treatment; compounds which are refractory to biological treatment
can be partially oxidized making them more amenable to biological oxidation.

     One of the major limitations with chemical oxidation is that the
oxidation reactions frequently are not complete (reactions do not precede to
C0_ and HLO) .  Incomplete oxidation may be due to oxidant concentration, pH,
oxidation potential of the oxidant, or formation of a stable intermediate
(Kiang and Metry, 1982).  The danger of incomplete oxidation is that more
toxic oxidation products could be formed.  Chemical oxidation is not well
suited to high-strength, complex waste streams.  The most powerful oxidants
are relatively non-selective and any oxidizable organics in the waste stream
will be treated. For highly concentrated waste streams this will result in the
need to add large concentrations of oxidizing agents in order to treat target
compounds.  Some oxidant such as potassium permanganate can be decomposed in
the presence of high concentrations of alcohols and organic solvents (Kiang
and Metry, 1982).


          10.1.11.3  Design Considerations


     Equipment requirements for chemical oxidation are simple and include
contact vessels with agitators to provide suitable contact of the oxidant with
the waste, storage vessels and chemical metering equipment.  Some
instrumentation is required to determine pH and the degree of completion of
the oxidation reaction.  Some oxidizing reagents react violently in the
presence of significant quantities of readily oxidizable materials.  Therefore
reagents must be added in small quantities to avoid momentary excesses.
                                     10-54
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          10.1.11.4  Technology Selection/Evaluation


     Oxidation reactions can be carried out using simple, readily available
equipment; only storage vessels, metering equipment, and contact vessels with
agitators are required.  However, implementation is complicated because every
oxidation/reduction reaction system must be designed for the specific
application.  Laboratory- and/or pilot-scale testing are essential to
determine the appropriate chemical feed rates and reactor retention times in
accordance with reaction kinetics.  Oxidation and reduction has not been
widely used in treating hazardous wastestreams.

     A major consideration in electing to utilize oxidation technology is that
the treatment chemicals are invariably hazardous, and great care must be taken
in their handling.  In particular, the handling of many oxidizing agents is
potentially hazardous and suppliers'  instructions should be carefully
followed.

     In some cases, undesirable byproducts may be formed as a result of
oxidation.  For example, addition of chlorine can result in formation of
bio-resistant end products which can be odorous and more toxic than the
original compound.  The possibility of this undesirable side reaction needs to
be considered when using chlorine for oxidation of wastewaters (Conway and
Ross, 1980).
          10.1.11.5  Costs
     Capital costs for chemical oxidation include costs for chemical storage,
chemical feeding and chemical mixing.  These costs can be approximated using
Figure 10-7.  Chemical costs are listed in Table 9-10.
     10.1.12  Chemical Reduction


          10.1.12.1  General Description


     Chemical reduction involves addition of a reducing agent which lowers the
oxidation of a substance in order to reduce toxicity or solubility or to
transform it to a form which can be more easily handled.  For example, in the
reduction of hexavalent chromium (Cr(Vl)) to trivalent chromium (Cr(lll))
using sulfur dioxide the oxidation state of Cr changes from 6+ to 3+ (Cr is
reduced) and the oxidization state of S increases from 2+ to 3+ (S is
oxidized).  The decrease in the positive valence or increase in the negative
valence with reduction takes place simultaneously with oxidation in chemically
equivalent ratios (Kiang and Metry, 1982).
                                     10-55
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                          + 3S02 + 3H20    Cr


     Commonly used reducing agents include sulfite salts (e.g. sodium
bisulfite, sodium metabisulfite, sodium hydrosulfite) sulfur dioxide and the
base metals (iron, aluminum and zinc).


          10.1.12.2  Applications/Limitations


     Chemical reduction is used primarily for reduction of hexavalent
chromium, mercury and lead.  There are currently no practical applications
involving reduction of organic compounds.


          10.1.12.3  Design Considerations


     Very simple equipment is required for chemical reduction.  This includes
storage vessels for the reducing agents and perhaps for the wastes, meterring
equipment for both streams, and contact vessels with agitators to provide
suitable contact of reducing agent and waste.  Some instrumentation is
required to determine the concentration and pH of the waste and the degree of
completion of the reduction reaction.  The reduction process may be monitored
by an oxidation-reduction potential (ORP) electrode (Kiang and Metry, 1982).


          10.1.12.4  Technology Selection/Evaluation


     Chemical reduction is well demonstrated for the treatment of lead,
mercury and chromium.  However, for complex waste streams containing other
potentially reducible compounds, laboratory and pilot scale tests will be
required to determine appropriate chemical feed rates and reactor retention
times.

     Chemical reduction can be carried out using simple, readily available
equipment and reagents.  Capital and operating costs are low and the process
is easy to implement.


          10.1.12.4  Costs
     Capital costs for chemical reduction include costs for chemical storage,
chemical  feeding, and chemical mixing.  These costs can be approximately using
Figure 10-7.
                                     10-56
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10.2  Solids Treatment


     10.2.1  Solids Separation


     This section describes equipment and methods used to separate solids from
slurries, and/or to classify contaminated soils or slurries according to grain
size.  The objective of separating solids from slurries is to attain two
distinct waste streams:  a liquid waste stream that can be subsequently
treated for removal of dissolved and fine suspended contaminants; and a
concentrated slurry of solids and minimal liquid that can be dewatered and
treated.

     Classification of particles according to grain size may be undertaken for
one of two reasons.  The first reason is that more efficient use can be made
of equipment and land area by taking advantage of the differences in settling
velocity of different sized particles.  For example, where only limited land
space is available, settling basins may be used to remove sand and gravel with
a high settling velocity and then high rate gravity settlers could be used to
remove fine-grained particles.

     There is recent evidence to suggest that classification by grain size is
important in managing hazardous waste contaminated soils and sediments because
of the apparent tendency of contaminants to adsorb preferentially onto
fine-grained materials such as clay and organic matter.  The separation of
solids by grain size and level of contamination could prove to be extremely
beneficial to the overall management (treatment, transport, and disposal) of
contaminated soil material.  Whereas relatively non-contaminated soils and
sediments may be disposed of in ordinary sanitary landfills or discharged back
into the stream, the highly contaminated solids must be disposed in a hazard-
ous waste landfill, incinerated or treated to render them non-hazardous.

     The most appropriate solids separation method for a given site depends
upon several factors,  including the following:

     •  Volume of contaminanted solids

     •  Composition of soils or sediments, including gradation, percent clays,
        and percent total solids

     •  Types of dredging or excavation equipment used, which determines the
        feed rate to solids separation and,  in the case of slurries,  the
        percent solids

     •  Site location and surroundings.   The available land area and ultimate
        or present land use may limit the type of system that can be  utilized.

     Solids separation methods addressed in this section include:   sieves and
screens,  hydraulic and spiral classifiers, cyclones,  settling basins  and
clarifiers.
                                     10-57
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     Many of the methods presented in this section are discussed in terms of
their ability to treat soils slurries or sediments containing particle within
a specific size range.  Table 10-15 summarizes the particle sizes which
correspond to various soil types.
          10.2.1.1  Screens and Sieves
     Sieves or screens consist of bars, woven wire or perforated plate
surfaces which retain particles of a desired size range while allowing smaller
particles and the carrying liquid to pass through the openings in the
screening surface.  Several types of screens and sieves have application for
solids separation at hazardous waste sites.
               a.  Grizzlies

     General Description—Grizzlies consist of parallel bars which are
frame-mounted on an angle to promote materials flow and separation.  Hoppers
are provided beneath the grizzly to collect removed material.  Bar spacing is
generally 1 to 5 inches apart depending upon the desired separation.  Both


     TABLE 10-15.  APPROPRIATE PARTICLE SIZES FOR VARIOUS SOIL CATEGORIES
     USCS Classification                U.S. Standard Sieve Size
     Gravel
          Coarse                        >3/4 in.
          Fine                          No. 4 - 3/4 in.
     Sand
          Coarse                        No. 10 - No. 4
          Medium                        No. 40 - No. 10
          Fine                          No. 200 -No. 40
     USCS Classification                Particle Size (u)

     Silt                               10 - 74
     Coarse Clay                        1.0 - 10
     Fine Clay                          <1.0
                                     10-58
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 fixed and vibrating grizzlies are available.  Grizzlies generally have a
 maximum width of 6 to 9 feet and a length of 12 to 18 feet (Mallory and
 Nawrocki, 1974).

     Applications/Limitations—Grizzlies are used primarily for scalping,
 i.e., removing a small amount of oversized material from a stream which is
 predominantly fines.  They are generally limited to separating materials which
 are 2 inches in diameter or coarser.  Another major function of the grizzly  is
 to reduce velocity of a slurry for subsequent processing operations (Mallory
 and Nawrocki, 1974).

     Technology Selection/Evaluation—Grizzlies offer a reliable method for
 removing coarse-grained material from slurries.  By doing so, they
 significantly improve the reliability and performance of subsequent solids
 separation methods and also reduce maintenance costs by minimizing the amount
 of abrasive material which reaches the screen, cyclone, etc.  Grizzlies
 contain no moving parts and are tough and abrasion resistant.  Therefore
 maintenance requirements are minimal.  Space requirements are also minimal and
 they can be installed in almost any area.  They can easily be arranged in
 series or parallel to accommodate very high flows or achieve classification  of
 coarse materials.
               a.  Moving Screens

     General Description—Screening of fine particles  from dry materials is
 frequently accomplished using moving  screens.  Types of moving screens
 include:

     •  vibrating screens

     •  revolving screens
     •  gyratory screens

     Vibrating screens are more widely used than other screen types,
 particularly for fine particle separation, because of  their larger capacity
 per unit of screen area and their higher efficiency (Perry and Chilton, 1973).
 Only the vibrating screen will be described in this section.

     Vibrating screens consist of a plane screening surface, usually stretched
 tautly and set into a rectangular frame having sufficient sidewalls to confine
 the material flow.  Figure 10-13 illustrates a typical vibrating screen.  They
may be composed of one, two or three  screening decks.  This allows for
 progressively finer separation and lower space requirements.  Screens are
 usually inclined at a slope of approximately 20° from horizontal, although
 horizontal screens are also available.  Vibration is produced by circular
motion in a vertical plane.  By vibration, the bed of material tends to
 develop a fluid state.  Larger particles remain on top of the bed while
 smaller particles sift through the voids and find their way to the bottom.
Once the fine particles have sifted through the bed of material,  the vibrating
 action increases the probability that the small particles will pass through


                                      10-59
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                  FIGURE 10-13. TYPICAL VIBRATING SCREEN
           Screening Surface
             Discharge End
                                                             Feed End
Source: Allis-Chalmers Corp., undated.
                                         10-60
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the  screen.  An  inclined  screen  allows  the  material  to cascade down the screen
surface,  increasing  the probability  that  small  particles will pass through
(Allis Chalmers, undated).

     Vibrating screens typically range  in size  from  about 3 to 10 feet wide
and  6 to  30  feet long.  Solids handling capacity ranges from 300 to 950 tph.

     Applications/Limitat ions—The  function of  vibrating screens is to
separate  particles by grain  size.   The  oversized particles are substantially
dewatered during the separation.  Typically,  vibrating screens are used to
separate materials in the  size range  of 1/8 inch up  to 6 inches.  However,
high speed vibrating screens are  also available for  separating finer particles
in the size  range of 4 to  325 mesh  (Chilton and Perry, 1973;  Mallory and
Nawrocki, 1974).  Although separation efficiencies are high with the vibrating
screen,  some fine particles  are  invariably  carried over with the coarse
particles.   Conventional vibrating  screens  are  best  suited for handling dry
materials.  Wet  or sticky  materials  tend  to blind the  screen.   Larger openings
can be used where blinding is a  problem,  but  this reduces the efficiency of
the  size  separation.  Vibrating  screens with  heated  decks are also available
to reduce moisture content,  although  they are not cost-effective for waste
streams with a high moisture content.   Because  of these limitations, the
conventional vibrating screens are  not  well suited for handling dredge
slurries.  Where the moisture content of  the  material  is high resulting in
blinding  wet screening with  sprays  can  be used.  Water is generally sprayed at
3 to 6 gpm per ton at a minimum  of  20 psi to  discourge blinding (Allis
Chalmers, undated).

     The  presence of abrasive material  in the feed may result in the need for
frequent  screen  replacement.  Therefore,  wastes should be carefully
prescreened using a  grizzly  or wedge-bar  screen.

     Relative to other types of moving  screens, vibrating screens generally
are  the most efficient, have lowest  space requirements and lowest maintenance
costs.  Vibrating screens  are the most  efficient of  the moving screens for
separating solids according  to grain  size.   However, their reliability is
adversely affected by the  fact that wet or  sticky materials tend to blind the
screen.   A water spray applied to a vibrating screen can significantly reduce
blinding.  The effectiveness of vibrating screens should be determined on a
case-by-case basis.

     The  presence of abrasive material  can  result in the need for frequent
screen replacement thereby increasing maintenance costs.

     Vibrating screens are relatively compact.   They can be installed in areas
where space is limited and are well suited  for  use in  mobile  treatment
systems.
     Cost—Costs for vibrating screens vary with  the  size  and  capacity  of the
screens,  The capital cost for a 10-ft. long, 5-ft. wide,  5-ft.  high  screen
with a capacity of 200 TPH is about $25,000.  Operation  and maintenance costs
                                     10-61
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for vibrating  screens  are relatively low compared  to  other  types of moving
screens (Allis  Chalmers,  undated;  Derrick Manufacturing  Corp.,  undated).


                c.   Stationary or fixed screens


     Stationary or  fixed  screens differ from moving  screens in  that they
posess no moving parts.   A continuous curved surface  and the  velocity of the
slurry across  the  surface provide  a centrifugal  force which holds the slurry
against the  screens  and  allows for separation.   One  type of fixed screen which
has potential  application for solids separation  at hazardous  waste sites is
the wedge-bar  screen or  bend-sieve.  A typical wedge-bar screen is illustrated
in Figure 10-14.  The  hydrosieve,  a modified wedge-bar  screen which uses water
pressure to  encourage  solids separation is also  used.

     General Description—The wedge-bar screen is  similar in  design to a
grizzly insofar as  it  consists of  parallel bars  which are frame-mounted on a
curved deck.   However, in the case of the wedged bar  screen,  bar spacing is
very close to  effect fine particle separation.   As the material enters the
feed inlet,  a  series of  baffles in the feed box  spread  the  material so that
the slurry is  evenly fed  over the  width of the curved screen  deck.  The slurry


                       FIGURE 10-14. WEDGE BAR SCREEN

                              Self-Adjusting Feed Baffle	
             Screen Retainer
                                                            Screen
                                                            Surface
                            _.      ^.  ,           Undersize Discharge
                            Oversize Discharge
             Source: Dorr-Oliver, 1983

                                      10-62
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flows through the  feed  inlet  at  the  top  of  the  feed  box and  flows  tangentially
down the surface of the  screen.  The  continuous curved  surface  together  with
the velocity across the  surface  provides  a  centrifugal  force which holds the
slurry against the screen  surface.  As the  slurry  strikes  the sharp edge of
the wedge bar, small particles are sliced off and  directed downward through
the slots along with most  of  the liquid.  Dewatered,  oversized  material  slides
on top of the screen surface  and is discharged.  The slicing action of the
wedge bars sizes the undersize particles  at  a smaller dimension than the slots
themselves and helps to  minimize blinding.   For example,  for a  slot width of 1
mm, the thickness of the slurry  layer being  shaved off  is  about 1/4 mm.   This
1/4 mm thick cut can transport particles  of  up to  1/2 mm  in  size;  plus 1/2 mm
solids pass over the screen (Hoffman-Muntner Corporation., 1978; Dorr-Oliver,
1980; Dorr-Oliver, 1983).

     Wedge-bar screens  normally  come  in  sizes of 2 to 6 feet wide, with
capacities of 30 to 200  gpm/ft .

     The hydrosieve or  pressure  screen is a  modification  of  the conventional
wedge-bar screen in which  the pressure of a  water  spray encourages more
efficient separation.   The water pressure helps to remove  fines that are
adhering to coarse grain sized materials  and breaks  up  clumps of material
which tend to clog the  screen.   Hydrosieves  with capacities  of  up  to 1500 gpm
are available.

     Application/Limitation—Wedge-bar screens and hydrosieves  are used  to
separate particles in slurry by  grain size.  The wedge-bar screen  is generally
less efficient in separating  solids  than  the vibrating  screen;  the oversized
material typically carries a  considerable amount of  fines.   The hydrosieve
minimizes this problem  by  employing a pressure spray which washes  the fines
from the coarser material.  Wedge bar screens may  be used  ahead of vibrating
screens.  This provides  a  higher solids  separation efficiency than the
vibrating screen alone  (Allis Chalmers, undated).

     Technology Selection/Evaluation—The wedge-bar  screen offers  a very low
cost method for separating solids according  to grain size.   However, the
effectiveness of the separation  methods  is not as  good  as  that  achieved  using
vibrating screens or cyclones.   Nevertheless, use  of a  water spray with  a
wedge-bar screen (hydrosieve) can significantly improve separation efficiency
by removing fines which  are sorbed to sands  and gravel.  The wedge-bar screen
contains no moving parts and  is  extremely easy to  operate  and maintain.   It is
also more resistant to  abrasion  than  the vibrating screen.   It  is  compact and
requires a minimal amount  of  space.

          10.2.1.2  Hydraulic Classifiers


               a.  General Description
     Hydraulic classifiers are commonly used to  separate  sand  and  gravel  from
slurries and classify them according to grain  size.  A  typical hydraulic
classifier is shown in Figure 10-15.  These units  consist  of elevated

                                     10-63
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DC
Ul
CO
CO
o
u
DC
Q
>


in

6

m
DC
D
O
                                                                                         I
                                                                                         c
                                                                                         o
               I
                                                                                         3
                                                                                         O
                                                                                         to
                                             10-64
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 rectangular  tanks with v-shaped  bottoms  to  collect  the material.   Discharge
 valves which are located  along the  bottom of  the  tank are  activated  by motor-
 driven vanes that sense the  level of  solids as  they accumulate.   The principal
 of  operation is simple.   The slurry is  introduced into  the feed end  of the
 tank.  As  the slurry  flows to the opposite  end, solids  settle out according  to
 particle size as a  result of differences in settling velocity.  Coarse
 materials  settle out  first near  the feed end  and  materials are progressively
 finer along  the length of the tank.   Manually adjusted  splitter gates below
 the discharge valves  can  be  used to selectively direct materials  of  specific
 grain sizes  to subsequent handling  and  treatment  (Eagle, 1981; Mallory and
 Nawrocki,  1974).  Classifying tanks are generally available  in sizes ranging
 from 8 to  12 feet wide and 20 to 48 feet long (Mallory  and Nawrocki, 1974).
 Solids handling capabilities are generally  limited  to 250  to 350  tph (Mallory
 and Nawrocki,  1974; Eagle Iron Works, 1981).


               b.   Applications/Limitations
     Hydraulic classifiers are used  to remove  sand  and gravel  size  particles
 from slurries and  to classify the removed materials according  to grain  size.
 Materials are recovered  from the classifier  at  about  30 percent moisture
 content (Written communication, 1984 Eagle Iron Works, Des Moines,  Iowa).
 They are capable of removing and classifying materials within  the size  range
 of 3/8 inch down to about 150 to 200 mesh (105  to 74 microns)  (Mallory  and
 Nawrocki, 1974; Eagle Iron Works, 1981).  The  upper limitation of 3/8 inch  is
 handled by prescreen- ing the wastes to remove  all  large materials.  Other
 solids separation  techniques are required to classify the fine-grained
materials «200 mesh).  Another limitation is  that  some fines  will  be removed
 with the sand and  gravel fraction.  This limitation is frequently overcome  by
 directing the solids to a spiral classifier  where they are washed to remove
 the fine-grained materials (see Section 10.2.1.3).  Hydraulic  classifers have
 a relatively low solids handling capacity and  are not well suited for handling
 large volumes of flow or high-solids concentrations.  A single average  sized
 tank with dimensions of 36 feet by 10 feet,  for example, can handle 5300 gpm
 when separating material down to 100 mesh and  only  1400 gpm when separating
material down to 200 mesh (Eagle Iron Works, 1981).

     Because of the inability of hydraulic classifiers to handle large  volumes
 of flow, a combination of solids separation methods may be advisable to reduce
 the number of hydraulic classifiers needed for  a large solids  handling
operation.  One possibility for reducing the number of classifers needed would
be to use these units to separate only those particles larger  than  105
microns.  Cyclones, hydrocyclones, or hydrosieves (see Sections 10.2.1.4 and
 10.2.1.1) could then be used to remove the fine sand fraction  (Mallory  and
Nawrocki, 1974).


               c.  Technology Selection/Evaluation

     Hydraulic classifers offer an effective method for operating and
classifying particles ranging in size from fine gravel to fine sands.   Some

                                     10-65
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fines are inadvertently  removed with  the  sand  and  gravel,  and the effective-
ness of the separation can be  improved by washing  the  collected  solids in a
spiral classifier to remove  the fines.

     Hydraulic classifier tanks are generally  designed and sized to be truck
mounted for mobile system applications.   Start-up  and  shut-down  can be
accomplished quickly.  Maintenance requirements  are  fairly simple.

     Use of hydraulic classifiers can be  easily  integrated with  other solids
separation methods and this  is advisable  where large flows are involved or
where classification of  fine-grained  materials (clays, silts) is required.
               d .  Co s t s

     Costs for hydraulic classifiers vary with  size  and  capacity of the
classifier.  For a size range of 24 to 49 feet  long,  8 to  12  feet  wide, and 8
feet deep; and a feed rate of 200 to 350 TPH, the  initial  cost  ranges from
$30,000 to $76,000 (Eagle Iron Works, 1981; Mallory  and  Nawroki,  1974).
          10.2.1.3  Spiral Classifier
               a.  General Description
     The spiral classifier consists  of  one  or  two  long,  rotating screws,
mounted on an incline within a rectangularly shaped  tub.   It  is  used  primarily
to wash adhering clay and silt from  sand  and gravel  fractions.   Figure 10-16
shows a typical configuration of a spiral classifier.

     The screw conveys settled solids from  a hydraulic  classifier (Section
10.2.1.2) up an incline to be discharged  through an  opening  at  the top of the
tub.  Fines and materials of low specific gravity  are  separated  from  sand and
gravel through agitation and the abrading and  washing  action  of  the screw, and
are removed along with the wastewater overflow at  the  bottom  of  the tub.   The
tumbling and rolling action caused by the continuous screw grinds particles
against each other and removes the deleterious material  coating  the sand
particles.  This tumbling action also aids  in  dewatering materials by breaking
the moisture film on the sand particles.  As the moisture  is  relieved of
surface tension, it is free to drain from the  material  (Eagle Iron Works,
1982).  The sands which are finally  discharged are substantially dewatered.

     In general, the greater the length of  the tub the  higher the degree  of
dewatering and the greater the screw diameter  the  larger the  capacity of  the
spiral classifier (Eagle Iron Works, 1982).  Classifiers are  available which
are capable of handling up to 950 tph.
                                      10-66
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DC
UI
V)
W
u
(B

6
                                           10-67
-------
               b.  Applications/Limitations


     Spiral classifiers are used primarily to wash, dewater,  and  classify
sands and gravels up to 3/8 inch in diameter.  They are not a  singularly
viable solids separation technology, but they are effective when  used  together
with the hydraulic classifier.  Spiral classifiers have a  large capacity and
are completely portable.


               c.  Technology Selection/Evaluation


     Spiral classifiers improve the efficiency of solids separation  achieved
with the hydraulic classifier by removing fine grained materials  attached  to
coarser particles.

     Spiral classifers are generally designed to be trailer mounted  for use  in
mobile treatment systems.  Start-up and shut-down can be accomplished  quickly
and maintenance requirements are simple.
               d.  Costs

     Costs for spiral classifiers vary with  size  and  configuration.   For a
size range of 22 to 34  feet long, 8 to 19  feet wide,  and  8  to  12  feet high the
initial cost of a spiral classifier ranges from $14,000 to  $77,000 for a
single-screw-type; and  from $37,000 to $150,000 for a double-screw-type.
Operational and maintenance costs vary with  the type  of power  utilized;  it can
be electricity, gas, or diesel  fuel (Eagle Iron Works, 1982; Mallory  and
Nawroki, 1974).


          10.2.1.4  Cyclones and Hydrocyclone


               a.  General Description


     Cyclones and hydrocyclones are separators in which solids that are
heavier than water are  separated by centrifugal force.  The major components
of a hydrocyclone are shown in  Figure 10-17.  A hydrocyclone consists of a
cylindrical/conical shell with  a tangential  inlet for feed, an outlet for the
overflow of slurry, and an outlet for the  underflow of concentrated solids.
Cyclones and hydrocyclones contain no moving parts.   The  slurry is fed to the
unit with sufficient velocity to create  a  "vortex" action that forces the
slurry into a spiral and, as the rapidly rotating liquid  spins about  the axis
of the cone, it is forced to spiral inward and then out through a centrally
located overflow outlet.  Smaller-sized  particles remain  suspended in the
liquid and are discharged through the overflow.   Larger and heavier particles
of solids are forced outward against the wall of  the  cone by centrifugal force


                                     10-68
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                FIGURE 10-17. TYPICAL CYCLONE
Feed
                                               Overflow
                                             Air Core
                                               Vortex  Finder
                            Underflow
 Source: Krebs Engineers, undated
                              10-69
-------
within the vortex.  The solids spiral around the wall of the cyclone and exit
through the apex at the bottom of the cone (Dorr-Oliver, 1984).

     Cyclones are available in an extremely wide range of sizes.  The smallest
units handle flows of only a few gallons per minute, while the largest units
can handle between 2000 and 7000 gpm, depending upon slurry composition
(Dorr-Oliver, 1984; Krebs Engineers, undated).  However, cyclones do not
scale-up as many other equipment types do.  In general, the larger the cyclone
diameter and inlet, the coarser the separation and the greater the cyclone
capacity.  The smaller the diameter and inlet, the finer the separation and
the lower the hydraulic capacity.  In order to remove small particles from
large volume slurries, it is necessary to use multiple, small-diameter
cyclones connected in parallel.  Banks of multiple cyclones, manufactured as a
single unit with a single feed pipe, are commercially available.

     Cyclones can also be connected in series or in various staging arrange-
ments to accomplish different objectives.  For example, a high degree of
particle size separation can be achieved by employing a bank of cyclones in
series with decreasing cyclone size and particle size removal in the direction
of flow.  It is also possible to achieve a higher underflow concentration and
a more clarified overflow by staging the cyclones.  The first stage of
cyclones could be used to classify the solids according to the desiged grain
size.  The second stage overflow cyclone could serve as a clarifier and the
underflow cyclone could serve as the concentrator.  However, the maximum
underflow concentration achievable with cyclones is about 60 percent, since
some liquid is necessary for solids discharge (Dorr-Oliver, undated).

     It should be noted that cyclones are available which can handle some
variation in flow rate and particle size by interchanging certain parts of the
cyclone.  For example, it is possible to add or delete sections to the cone,
or to change the size of the vortex finder.


               b.  Applications/Limitations


     Cyclones are available for separating or classifying solids over a broad
particle size range, from 2000 microns down to 10 microns.  However, in
hazardous waste site applications they would be used primarily to remove
smaller size particles from slurries and in situations where a sharp
separation by particle size is needed.  They are particularly applicable to
situations where space is limited.

     Cyclones are generally not effective for slurries with a solids
concentration greater than 30 percent, for highly viscous slurries, or for
separation of particle sizes with a specific gravity of less than about 2.5 to
3.2 (Krebs Engineers, undated).  Slurries with a high clay content exhibit
high pseudoplasticity or high viscosity and cannot be effectively removed
using cyclones or hydrocyclones (Oklahoma State University, 1973).
                                     10-70
-------
     Cyclones are highly vulnerable to clogging by oversized particles, and a
high degree of prescreening (or use of progressively smaller cyclones in
series) may be needed to avert clogging.


               c.  Technology Selection/Evaluation


     Cyclones offer an effective means of separating and classifying solids
over a broad range of particle size, provided the solids concentration is not
too high and the slurry is not too viscous.  Cyclones are flexible insofar as
they can easily be arranged in parallel to accomplish fine size separation, or
in various series or staging arrangements to improve classification of the
overflow or concentration of the underflow.  They can also be easily
integrated with other solids separation methods.  However, each individual
cyclone is capable of handling only very limited variations in flow rate and
particle size.

     The capital and operating costs of cyclones are relatively low.  They are
simple to operate and easy to maintain since they contain no moving parts.
Liners require periodic replacement but this can be done easily.

     Cyclone assemblies take up less space than most solids separation
equipment and are well-suited for tight locations.  Because of their
compactness and simplicity of operation, cyclones are also well-suited for
inclusion in mobile treatment systems.
               d .  Co s t s

     The cost of cyclones varies widely according to the size and the number
of cyclones placed in series.  The feed rate can vary from a few gallons per
minutes up to several thousand gallons per minute, and the size of each
cyclone can vary from 1/2 inch to 30 inches in diameter.  Initial costs for
cyclones can be as low as $5,000 and indefinately high, depending on the
configuration (Hoffman Muntnor Corp., 1978; Krebs Engineers, undated).


     10.2.1.5  Settling Basin

     A settling basin, as described in this section, is an impoundment, basin,
clarifier, or other container that provides conditions conducive to allowing
suspended particles to settle from a liquid by gravity or sedimentation.  The
slurry is introduced into the basin and settling of solids occurs as the
slurry slowly flows across the length of the basin.  Flow out of the opposite
end of the basin is reduced in its solids content.

     The size of an impoundment basin or clarifier is ideally determined by
dividing the critical settling velocity by the overflow rate.  The critical
settling velocity is a function of the diameter, and specific gravity of the
smallest particle size requiring removal and the viscosity of the water.
                                     10-71
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However, ideal settling conditions are never achieved and  the actual design  of
the required surface area must make allowance for turbulence, short
circuiting, and scour velocity.  Detailed procedures for sizing  sedimentation
basins can be found in most wastewater engineering handbooks.

     Settled solids accumulate on the bottom of settling basins  where  they are
temporarily stored.  As the volume of accumulated solids increases, the
effective size of the basin decreases, reducing the basin's effectiveness or
efficiency.  Accumulated solids must be periodically or continuously removed
in order for the basin to perform as intended.

     Commonly used types of settling basins are described  below:

               a.  Impoundment Basin

     General Description — An impoundment basin  is an earthen  impoundment or
diked area that is lined in a manner that is appropriate for protecting
underlying groundwater.  An adjustable weir is provided to control  overflow
rate.  A typical impoundment basin is illustrated in Figure 10-18.

     Multiple basins, or bulkheads that separate  a single  basin  into
compartments can be used in parallel to allow continuous sediment/water
separation while accumulated solids are being removed from individual  basins.
Multiple basins can also be connected in  series in order to separate solids
according to grain size.  Each basin would be designed to  retain sediments of
increasingly smaller grain size.

     Applications/Limitat ions — Impoundment basins are used to  remove
particles in the size range of gravel down to fine silt (10 to  20 microns with
flocculants) (Mallory and Nawrocki, 1974).  They  are also  used  to provide
temporary storage of dredged material and to classify sediment  particles
according to grain size.

     Impoundment basins are particularly  well-suited for large-scale dredging
operations, provided there is adequate land space available for  their
construction.  They are not suitable for  congested areas,  or for areas where
adequate measures cannot be taken to protect groundwater supplies (e.g., high
groundwater table).

     A major limitation with the use of impoundment basins is that  unlike
clarifiers, they have no mechanism for solids collection.   Therefore,
mechanical dredges (e.g., clamshells, backhoes) are typically used  to  remove
the  settled solids.  This greatly increases the operational costs associated
with use of impoundment.
               b.   Conventional  Clarifers

     General Description  — Conventional clarifers  are  rectangular or circular
 settling basins which  are typically  equipped  with built-in solids collection
 and  removal mechanisms.
                                      10-72
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                              FIGURE 10-18.
 CONCEPTUAL DIAGRAM OF A DREDGED MATERIAL CONTAINMENT AREA
                      MOUNDED COARSE-GRAINED
                      DREDGED MATERIAL
                                DEAD ZONE
                             AREA FOR SEDIMENTATION
                                        .DEAD ZONE
                                    PLAN
        PONDING DEPTH.


    FOR^DlMEf'jfAfioN"
                                                         FREEBOARD
                                   FOR HNE-GRANED
                               DREDGED MATERIAL STORAGE
COARSE-GRAINED
DREDGED MATERIAL
 CLAY LINER SYSTEM
                                                             EFFLUENT
                                                             TO TREATMENT
                             CROSS SECTION
Source: Adapted from Palermo et al., 1978
                                10-73
-------
     Typically, in a rectangular clarifier  a  flow with relatively high
suspended solids is introduced at one end of  the  clarifier,  solids settle
along the length of flow, and a flow with relatively  low suspended solids
leaves the clarifiers through trough-type overflow weirs.   In  most rectangular
clarifiers flights extending the width of the  tank move the  settled sludge
toward the inlet end of the tank.  Some designs move  the sludge toward the
effluent end of the tank, corresponding to  the direction of  flow of the
density current.

     Circular clarifiers are of two general types.  With the center feed type,
the waste is fed into a center well and the effluent  is pulled off at the weir
along the outside.  With a peripheral feed  tank,  the  effluent  is pulled off at
the tank center.

     Figure 10-19 illustrates a center feed type  clarifier.  The circular
clarifer can be designed for center sludge withdrawal or vacuum withdrawal
over the entire tank bottom.
                        FIGURE 10-19. CIRCULAR CLARIFIER
                      Walkway truss
                                                      Skimmer

                                                     ,	\
                                             Influent pipe
                                                               Side water
                                                               depth
         Source: Dorr-Oliver, 1976

     Many clarifiers are equipped with  separate  zones for chemical mixing and
precipitation, flocculation  and  settling.


     Applications/Limitations  — Clarifiers  are  able to remove particles down
to 10 to 20 microns (Mallory and Nawrocki,  1974)  in diameter,with the use of
flocculants.  They can  also  be used  to  produce a  thickened sludge with a
solids concentration of about  4  to 12 percent (Metcalf and Eddy, 1979) and to
separate solids by grain size.   This would  be accomplished by connecting
clarifiers in series and providing a retention time sufficient to removal
materials of a certain  grain size.

     Clarifiers are best suited  to small-  to moderate-scale cleanup operations
or to large-scale operations where impoundment basins will not adequately
                                      10-74
-------
protect groundwater supplies.  Clarifiers can be barge mounted for solids
separation during dredging operations.

     Circular clarifiers are generally more efficient in solids removal.
However, rectangular tanks are more suitable for barge-mounting and where
construction space is limited.  In addition a series of rectangular tanks is
cheaper to construct due to the shared wall concept.

               c.  High Rate Clarifier

     General Description — High rate clarifiers use multiple "stacked"
plates, tubes, or trays to increase the effective settling surface area of the
clarifier and decrease the actual surface area needed to effect settling.
Figure 10-20 illustrates a high rate clarifier.  High rate clarifiers allow a
higher flow rate per unit of actual surface area (loading rate) than do
conventional clarifiers, thus the name "high rate" clarifiers.  The trays,
plates, or tubes also induce optimum hydraulic characteristics for sedimen-
tation by guiding the flow, reducing short circuiting and promoting better
velocity distribution.

     High rate clarifiers are able to handle between 2 to 10 times the loading
rate of conventional clarifiers and therefore require limited land use (Jones,
Williams and Moore, 1978).  Package units capable of handling 1,000 to
2,000 gpm are available and are easily transportable by truck or barge.

     Applications/Limitations — High rate clarifiers are best suited to
small- to moderate-scale cleanup operations, or to large-scale operations
where construction of earthen impoundments will not adequately protect
groundwater.  High rate clarifiers are particularly applicable to cleanup
operations where land space is limited and where barge mounting of clarifiers
is required.

     High rate clarifiers are not suitable for removal of particles larger
than 0.1 inch or less than 10 microns.  Use of high rate gravity settlers has
not been demonstrated for applications in solid/water separation and they are
generally used in applications with lower solids concentrations (Mallory and
Nawrocki, 1974).  There is the possibility that cohesive sediments or soils
may clog the channels, tubes, or plates (Jones, Williams and Moore, 1978).

               d.  Technology Selection/Evaluation

     Sedimentation employing impoundment basins and conventional clarifiers is
a well established technology for removing particles ranging in size from
gravel down to fine silt.  However, proper flocculation is essential to ensure
removal of silt-sized paticles.  Sedimentation methods have not been widely
employed for classifying solids according to particle-size.  They can be
expected to be less effective in classifying solids than other methods
described in this section (e.g., classifier, cyclones, and screens).

     Impoundment basins have a high capital and operating cost.  For this
reason their use is generally limited to large-scale cleanup operations.
                                     10-75
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                     FIGURE 10-20. HIGH RATE GRAVITY SETTLER
 FLOW DISTRIBUTION ORIFICES
OVERFLOW BOX
                                         DISCHARGE FLUMES


                                                  /FEED BOX
                                                                   FLOCCULATION TANK
                                    SLUDGE HOPPER
                                     (REMOVABLE)
       Source: Parkson Corp., 1984
                                              10-76
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Impoundment basins also pose the greatest potential for secondary impacts of
all solids separation methods; contaminants may leach into groundwater if the
liner system is not properly designed and the large surface area of the
impoundment can result in volatilization of contaminants and localized air
pollution problems.

     Impoundment basins require a long set-up time and the need to obtain
construction permits can further delay the start-up of the cleanup operation.
Conventional clarifiers and high-rate clarifiers eliminate some of the
problems associated with impoundment basins.  Operating costs are
substantially less because clarifiers have a build-in solids collection
system.  Clarifiers also pose no threat to groundwater contamination.
However, capital costs associated with the use of clarifiers can also be quite
high for a large-scale cleanup operation.

     Both types of clarifiers can be barge mounted in areas of limited space.
High-rate clarifiers with their relatively small space requirements, may be
the only suitable sedimentation method in congested areas.  Clarifiers and
impoundment basins are easy to operate and maintain.

     10.2.2  Dewatering


     Dewatering is a physical unit operation used to reduce the moisture
content of slurries or sludges in order to facilitate handling and prepare the
materials for final treatment or disposal.  Devices which can be used to
dewater slurries or sludges include gravity thickeners, centrifuges, filters,
and dewatering lagoons.  Selection of the most appropriate method depends on
such factors as the volume of the slurry, solids content of the waste stream,
land space availability and the degree of dewatering required prior to
treatment or disposal.

     Although several of the dewatering methods are extremely effective in
removing water, the solids are often not sufficiently dry to meet requirements
for final disposal, and require further treatment to fixate or solidify the
wastes (Section 10.3).  The contaminated water generated during dewatering
generally contains hazardous constituents as well as several hundred to
several thousand mg/1 suspended solids,  and will require additional treatment
(Section 10.1).
          10.2.2.1  Gravity Thickening


               a.  General Description
     Gravity thickening is generally accomplished in a circular tank, similar
in design to a conventional clarifier.   The slurry enters the thickener
through a center feedwell designed to dissipate the velocity and stabilize the
density currents of the incoming stream (Figure 10-21).  The feed sludge is
                                     10-77
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allowed to thicken and compact by  gravity settling.   A sludge blanket is
maintained on the bottom  to help concentrate  the sludge.   The clarified liquid
overflows the tank and the underflow  solids  are raked to  the center of the
tank and withdrawn by gravity discharge  or pumping.   Flocculants are often
added to the feed stream  to enhance agglomeration of the  solids and promote
quicker or more effective settling  (Metcalf  and Eddy, 1979;  Dorr-Oliver,
1981).  Tanks are usually constructed of concrete or steel.

     Gravity thickener size and specifications  depend on  the following
factors:  maximum flow, type of wastes,  pH, volume of solids/day, percent
solids, specific gravity, maximum  particle size, and percent solids required
in the underflow.
               b.  Applications/Limitations
     Gravity thickeners  are  used  to  concentrate slurries and are capable of
achieving a solids concentration  of  approximately 2 to 15 percent (USEPA,
1979).  They generally produce  the  thinnest and least concentrated sludge of
all the dewatering methods described in this section.  The intent in using a
gravity thickener is usually to reduce  the hydraulic load of a slurry that is
to be fed to a more efficient dewatering method,  such as filtration or centri-
fugation.  They also provide a  high  sludge storage capacity.  Conventional
gravity thickeners require large  land areas for operation and therefore are
                       FIGURE 10-21. GRAVITY THICKENER
                                             Coitrteiy Link Btll
                                             SCRAPER BLADES
                                       2 UNDERFLOW
                               ELEVATION
     Source: Gulp, Wesner, and Gulp, 1978
                                      10-78
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not applicable where space is restricted.   However, high-rate  gravity
thickeners  designed to provide up  to  15  times the throughput of  a  conventional
thickener are  available and can reduce  land requirements considerably
(Dorr-Oliver,  1981).
                c.   Technology Selection/Evaluation
     Gravity  thickening provides a simple,  low maintenance method  for
concentrating  slurries, thereby reducing  the hydraulic load to  subsequent
dewatering  processes.   They are suitable  for operations where a high degree of
operator  supervision cannot be provided.   Because of the requirements  for a
large surface  area,  localized air pollution and odors may be significant.


                d.   Costs

     Equipment  costs for gravity thickeners are illustrated in Figure  10-22.
Costs are based on  the use of a circular  reinforced concrete basin  and related
drive and motor.

          FIGURE 10-22. GRAVITY THICKENING CONSTRUCTION COSTS, 1975*
                 i
                 o
                 s
                          2  S 4 S6789     ^  34 S 6 T t«    I  it »«T«t
                                   100           1,000
                                    Area, ft2

           •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
           (multiply value shown on this figure by 1.908)
           Source: Gulp, Wesner, and Culp, 1978
                                      10-79
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          10.2.2.2  Dewatering Lagoons


               a.  General Description


     Dewatering lagoons use a gravity or vacuum assisted underdrainage system
to remove water.  The base of the lagoon is lined with clay plus a synthetic
liner or other appropriate liner material to prevent migration of contaminants
into the underlying soils and groundwater.   At a minimum, the liner consists
of a low permeability clay layer which is several feet thick.  When the lagoon
is no longer in use, the clay liner is excavated and properly disposed of.   In
some instances this design may not be adequate to protect groundwater
supplies.  A combination clay/synthetic liner and a secondary leachate
collection system are required in some instances.

     The underdrainage system can be designed and operated using one of the
following approaches:

     •  Gravity underdrainage - This system consists of a filler material
        (well-graded sand or filter fabric) underlain by a porous free-
        draining gravel layer.  Perforated drainage pipe is embedded in the
        gravel.  The drainage pipe network is designed with flow gradients
        leading towards a central collection point or sump.  Information on
        the hydraulic design of a gravity drainage system can be found in
        Section 5.2.

     •  Vacuum pumping - Vacuum pumping systems can use either pumped wells or
        wellpoints.  Pumped wells with large vacuum pumps may be installed
        directly in the waste material.  Wellpoints may be used, provided they
        are installed to the depth of an underlying sand filter.  Installation
        of wellpoints directly in the sludge, contaminated sediments^ or soils
        is not cost-effective, because it is necessary to space the wellpoints
        very close together in order to dewater low permeability material
        (Haliburton, 1978).  Information on the design of wells and wellpoints
        can be found in Section 5.1.

     •  Vacuum assisted drying beds - Vacuum assisted drying beds use a porous
        media filter plate set above an aggregate filled support plenum which
        drains to a sump.  A relatively small vacuum pump is connected to
        drain a vacuum from the sump.  The vacuum is activated when the volume
        of the slurry has been reduced by half due to gravity drainage.  The
        vacuum holds until the solids crack, allowing air through the bed
        (USEPA, 1982).

     •  Electroosmosis - This technique involves a process in which a direct
        current electrical potential is set-up in the soil by means of
        electrodes.  This electric potential induces the flow of water in the
        pores of the fine-grained sediment or sludge towards the negative
        pole, or cathode.  A line of wells or wellpoints can be installed to
        intercept and remove the water (Mallory and Nawrocki, 1974).


                                     10-80
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               b.  Applications/Limitations


     Dewatering lagoons are best suited to large-scale dewatering operations
where the volume of sludge or sediment would require an inordinately large
number of mechanical dewatering units (e.g., filters or centrifuges).  Lagoons
are one of  the more effective dewatering methods.  A gravity dewatering system
is capable  of achieving 99 percent solids removal and a dewatered cake of 35
to 40 percent solids after 10 to 15 days (based on municipal sludges)
(DeRenzo, 1978; USEPA, 1982).  Vacuum assisted systems may be capable of
achieving a dry cake in a shorter retention time.

     The major limitations on the use of dewatering lagoons is that they
require large land areas and long set-up times.  Because of their large
surface area they may not be well suited to areas with heavy rainfall or to
areas where long periods of freezing would prevent dewatering.

     Each of the types of dewatering lagoons described in this section has its
own specific applications and limitations.

     Gravity drainage systems have the lowest operating costs.  However,
dewatering  is achieved at a relatively slow rate and this may result in the
need for more land area than required with the other methods.  Gravity
drainage systems are also more prone to clogging, particularly if the system
is not carefully designed.

     Vacuum pumping or vacuum assisted dewatering beds are capable of
dewatering  at a much more rapid rate than gravity systems.  Vacuum assisted
dewatering  beds reportedly increase the rate of dewatering by about 50 percent
(with a negative pressure of 8 psi or less) (Haliburton,  1978).   However,  they
require a higher degree of maintenance and are considerably more costly to
operate than gravity systems.

     Electroosmosis is a very costly technique which would be limited to
dewatering  of very fine grained (2 to 10 microns), very hazardous and
difficult to dewater solids.
          c.  Technology Selection/Evaluation


     Dewatering lagoons provide an effective means of dewatering solids.  They
are also versatile in that they can provide storage capacity for solids prior
to disposal.  Of all the dewatering technologies they require the largest time
to implement and have the greatest potential for secondary impacts due to
localized air pollution and groundwater contamination.  Operating costs are
higher than other dewatering technologies because of the need to remove the
solids with mechanical dredging equipment.
                                     10-81
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          10.2.2.3  Centrifuges


               a.  General Description


     Centrifugal dewatering is a process which uses the force developed by
fast rotation of a cylindrical drum or bowl to separate solids and liquids by
density differences under the influence of centrifugal force.  Dewatering is
usually accomplished using solid bowl or basket centrifuges.  Disc centrifuges
are also available and are mainly used for clarification and thickening.
Figures 10-23 through 10-25 illustrate the three types of centrifuges.

     The operation of the solid-bowl centrifuge is a continuous process.  The
unit consists of a long bowl, normally mounted horizontally and tapered at one
end.  Sludge is introduced into the unit continously and the solids concen-
trate on the periphery.  A helical scroll within the bowl, spinning at a
slightly different speed, moves the accumulated sludge towards the tapered end
where additional solids concentration occurs prior to discharging the solids
(USEPA, 1982a and USEPA, 1979).

     In the basket centrifuge, flow enters the machine at the bottom and is
directed toward the outer wall of the basket.  Cake continually builds up
within the basket until the centrate, which overflows a weir at the top of
this unit, begins to increase in solids.  At that point, feed to the unit is
shut off, the machine decelerates, and a skimmer enters the bowl to remove the
liquid layer remaining in the unit.  A knife is then moved into the bowl to
cut out the cake which falls out the open bottom of the machine.  The unit is
a batch device with alternate charging of feed sludge and discharging of
dewatered cake (USEPA, 1982a and USEPA, 1978).

     In the disc centrifuge, the incoming stream is distributed between a
multitude of narrow channels formed by stacked conical discs.  Suspended
particles have only a short distance to settle, so that small and low density
particles are readily collected and discharged continuously through fairly
small orifices in the bowl wall.  The clarification capability and throughput
range are high, but sludge concentration is limited by the necessity of
discharging through orifices of 0.05 inches to 0.1 inches in diameter.
Therefore, it is generally considered a thickener rather than a dewatering
device (USEPA, 1978) .


               b.  Applications/Limitations


     Centrifuges can be used to concentrate or dewater soils and sediments
ranging in size from fine gravel down to silt.  Effectiveness of
centrifugation depends upon the particle sizes and shapes, and the solids
concentration among other factors.  Data from the dewatering of municipal
sludges (where extensive information is available), indicate that solids
concentrations ranging from about 15 to 40 percent are achievable with the
                                     10-82
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                           FIGURE 10-23.
    SCHEMATIC OF TYPICAL SOLID BOWL DECANTER CENTRIFUGE
                                                                   FEED
                                            COVER
 ."•'•." OEWATERE0
.' '•'.'.    SOLIDS
Source: USEPA, 1979
                                10-83
-------
                     FIGURE 10-24.
  GENERAL SCHEMATIC OF IMPERFORATE BASKET CENTRIFUGE
                       FEED
           POLYMER
SKIMMINGS
                                                    KNIFE
               CAKE
                          CAKE
                         10-84
-------
                         FIGURE 10-25.
             SCHEMATIC OF A DISC NOZZLE CENTRIFUGE
                FEED
           EFFLUENT
           DISCHARGE
 FEED
 EFFLUENT
DISCHARGE
CONCENTRATING
CHAMBER
SLUDGE
DISCHARGE
                                                    ROTOR
                                                     BOWL
                                                    ROTOR
                                                   NOZZLES
               SLUDGE
            DISCHARGE
                       RECYCLE FLOW
   Source: USEPA, 1979
                           10-85
-------
solid bowl centrifuge.  For the basket centrifuges the cake solids
concentration typically ranges from about 9 to 25 percent.  Solids capture
typically ranges from about 85 to 97 percent with chemical conditioning, both
for the solid bowl centrifuge and the basket centrifuge.  Disc centrifuges can
concentrate a 1 percent sludge to a 6 percent solids (USEPA, 1978; USEPA
1982a).

     Centrifuges are capable of removing particles as small as 1 micron in
diameter.  However, removal efficiencies are reduced dramatically for
particles smaller than 10 microns (Krizek, Fitzpatrick and Atmatzidis, 1976).

     Although the basket centrifuge does not acheive as dry a cake as does the
solid bowl centrifuge, it has the advantage of being able to handle hard to
dewater sludges and is not significantly affected by grit.  It has the highest
capital cost but lowest operation and maintenance cost of the three centrifuge
types (USEPA, 1979 and USEPA, 1982b) .  A major limitation is that it must be
operated on a batch basis.

     The solid bowl centrifuge is very flexible in that it can handle higher
than design loadings, such as temporary increases in hydraulic loading or
solids concentrations; however, the cake solids content may be reduced.
Higher feed rates make the solid bowl centrifuge better suited for large-scale
dewatering operations.  Maintenance and pretreatment requirements are more
extensive than for the basket centrifuge.  The scroll of the solid bowl
centrifuge is very susceptable to abrasion.  This results in the need to
degrit the effluent (USEPA, 1979 and USEPA, 1982a).

     The disc centrifuge has more limited application at hazardous waste sites
than the other types of centrifuges.  Although it can yield a highly clarified
centrate even without the use of chemicals, the percent solids concentration
is low, maintenance requirements are relatively high, and pretreatment
requirements (grit and fibrous material removal) are extensive.


               c.  Technology Selection/Evaluation


     Centrifugation offers a simple, clean and reliable method for dewatering
sludges and other solids.  They are less effective than filtration methods and
dewatering lagoons, but more effective than gravity thickeners.  Centrifuges
are compact and are well suited to use in mobile treatment systems.

     Although reliable for their intended function,  centrifuges generated a
centrate and a sludge which require further treatment prior to disposal.
Suspended solids levels from centrifugation may be as high as several thousand
parts per million.

     Since centrifugation relies on the settling of particles according to
density, the process tends to classify the solids, settling the heavier
particles first.  Dewatering processes which rely on filtration achieve a more
even distribution of solid capture.  It is possible  for a buildup of fines to
                                     10-86
-------
occur in the effluent from centrifugation, particularly if the centrifuge is
operating improperly due to inadequate solids conditioning or due to a mal-
function (USEPA, 1982a).  Since most organic and inorganic waste constituents
tend to sorb to fine clay and silt particles, this may result in unacceptable
levels of contaminants in the overflow.

     Advantages of centrifuges for thickening and dewatering methods include
relatively limited space requirements and fast start-up and shut-down.  They
also generate little or no air emissions since the process is essentially
enclosed.
               d.  Costs
     This section presents construction and O&M costs for basket and solid
bowl centrifuges.  It should be recognized that the curve for construction
cost is not capital cost.  The curve does not include costs for special site
work, general contractor overhead and profit, engineering, land, legal,
fiscal, and administrative work and interest during construction.  These cost
items are all more directly related to the total cost of a project rather than
the cost of any one of the individual unit processes.  These costs are
therefore most appropriately added following cost summation of the individual
unit processes, if more than one unit process is required.  Typically, these
costs add 35 to 45 percent, depending on project size and complexity, to the
actual construction costs which are shown in the curves (USEDA, 1982a).

     Construction costs include housing for the centrifuges. Housing costs may
not be applicable for hazardous waste sites because of the short time period
the unit will be on-site.

     No costs were available for mobile treatment units involving use of
centrifuges.

     Basket Centrifuge — Figure 10-26 shows construction costs for single and
multiple basket centrifuges with capacities ranging from 4,000 to 700,000 gpd.
Centrifuge costs are for automatic machines operating on a preprogrammed
cycle, an approach which requires only minimal operator attention.

     In addition to the basic machines, the costs include equipment for
polymer preparation, storage, and application.  If other conditioning
chemicals are used, the costs would have to be adjusted accordingly.  The
costs do not include sludge and centrate pumping, sludge conveying, and sludge
storage.  It was assumed that centrifuges are located in two story concrete
block buildings with bottom discharge to trucks or storage bins.  Housing
requirements were developed from equipment manufacturers'  recommended layouts
(USEPA, 1982a).

     Figures 10-27 and 10-28 present O&M costs for basket centrifuges.
Electrical energy requirements were computed from connected and operating
                                     10-87
-------
       FIGURE 10-26. CONSTRUCTION COST FOR BASKET CENTRIFUGES *
i
9

2
1 0.000.
1
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• •
                                 10.000
                                TOTAL tUCHINC CAMCtTY -»<
                                    1 00.000
                              TOTAL HACHINC CArAC
                                             1 .000,000
           •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
            (multiply value shown on this figure by 1.193)
           Source: USEPA 1982a

horsepower information  provided by equipment manufacturers.   Basket centrifuge
operating horsepower, computed on the basis of  a  complete cycle involving
machine acceleration, sludge feeding, skimming, decelerating, and sludge
plowing, averages  40 to 60  percent of the connected  horsepower.  Electrical
power for polymer  preparation and feeding is included,  but energy for sludge
pumps, centrate pumping and sludge conveying equipment  is not included.

     Maintenance  costs  were obtained from equipment  manufacturers and from
operating installations and represent an industrywide average of annual
expenditures  for maintenance, replacement parts,  lubrication, and other
consumable items  associated with basket centrifuge operation.  Maintenance
material costs  do  not include the cost of polymers.

     Labor requirements for O&M assume 24 hours per  day of operation, with
occasional downtime for maintenance as required.   The major portion of the
operating labor is devoted  to machine start-up  and adjustment, polymer
preparation,  and  required maintenance (USEPA,  1982a) .
                                       10-88
-------
  FIGURE 10-27. BASKET CENTRIFUGES-BUILDING ENERGY, PROCESS ENERGY
                 AND MAINTENANCE  MATERIAL REQUIREMENTS*
                     1  •
                       1000
                       :
                                                 BUILDING
                                                 ENERCY,
                               0.000
                                  s •ritiocoo 2 S 4 9 t re

                                     FCCD sujooe FLOW RATE -utt
                                                   I.OOO.C
                                         100.000       I .OOO.OOO

                                   FEED SLUOflE FLOW HATE -Hurt/Mr
FIGURE 10-28. BASKET CENTRIFUGES-LABOR AND TOTAL ANNUAL OPERATION

              AND MAINTENANCE COST*

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-------
      It  should  be recognized that operation and maintenance costs will vary
widely depending  on sludge dewatering characteristics  and  specific operating
conditions  related to the installation, and appropriate  adjustment should be
made  if  conditions vary significantly from those  stated  above (USEPA, 1982a).

      Solid  Bowl Centrifuge (High G)—Construction costs  for solid bowl
centrifuges  are shown in Figure 10-29.  Machine throughput is significantly
affected by  the polymer dosage, and therefore the construction cost for a
given feed  rate varies with the polymer dose.  In this figure, single machines
were  assumed  to be used for feed rates up to 500  gpm,  with multiple units
being usedfor higher feed rates.  All machines are equipped with automatically
controlled  eddy current backdrive and have sintered  tungsten carbide conveyor
tips.  Polymer  storage preparation, and feed equipment is  included in the
costs, but  costs  for sludge feed pumping and centrate  pumping are not included
(USEPA,  1982a).
   FIGURE 10-29. CONSTRUCTION COST FOR A HIGH G SOLID BOWL CENTRIFUGES*
1
9
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                                      10         100
                                   MUMHC CAHCITr - MOT/W
         •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
          (multiply value shown on this figure by 1.193)
         Source: USEPA, 1982a
                                      10-90
-------
     Operation and Maintenance Cost for solid bowl centrifuges are shown in
Figure 10-30 and 10-31.  Process energy was calculated from information
supplied by a manufacturer of high G centrifuges and assumes use of an eddy
current backdrive.  Energy requirements could be reduced between 5 to 20
percent if the backdrive is not utilized.  Included in the process energy
requirements are the main drive motor, the eddy current backdrive, and equip-
ment required for polymer preparation and feed.  Energy required for feed
sludge pumping and handling of the dewatered sludge is not included.

     Maintenance material requirements include replacement of the conveyor
tips every 30,000 hours of operation, as well as replacement of other
necessary components of the centrifuge and the electrical controls.

     Operation and maintenance labor requirements are based on 24 hours per
day of continuous operation.  Most operational labor is devoted to polymer
preparation and machine start-up and adjustment.  Occasional maintenance is
required for lubrication, with more extensive maintenance required
approximately every 30,000 hours for replacement of the sintered tungsten
carbide conveyor tips.

     The cost curves presented do not include the cost of polymer.  The
polymer dosage is highly dependent on the characteristics of the sludge being
dewatered, and polymer dosage will also have a great influence on the
throughput of the centrifuge.


          10.2.2.4  Filtration


               a.  General Description


     Filtration is a physical process whereby particles suspended in a fluid
are separated from it by forcing the fluid through a porous medium.  Three
types of filtration are commonly used for dewatering:  belt press filtration,
vacuum filtration, and pressure filtration.

     Belt filter presses employ single or double moving belts to continuously
dewater sludges.   As Figure 10-32 illustrates,  the belt press filtration
process includes three stages:  chemical conditioning of the feed, gravity
drainage to a nonfluid consistency and dewatering.  A flocculant is added
prior to feeding the slurry to the belt press.   In the next step, free water
drains from the conditioned sludge.   The sludge then enters a two-belt contact
zone, where a second upper belt is gently set on the forming sludge cake.  The
belts with the captured cake between them pass  through rollers of generally
decreasing diameter.  This stage subjects the sludge to continuously
increasing pressures and shear forces.   Progressively more and more water is
expelled throughout the roller section to the end where the cake is dis-
charged.   A scraper blade is often employed  for each belt at the discharge
point to remove the cake from the belts (USEPA,  1982).
                                     10-91
-------
FIGURE 10-30. HIGH G SOLID BOWL CENTRIFUGES-BUILDING ENERGY, PROCESS ENERGY AND
             MAINTENANCE MATERIAL REQUIREMENTS*
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           FIGURE 10-31. HIGH G SOLID BOWL CENTRIFUGES-LABOR AND TOTAL
                        ANNUAL OPERATION AND MAINTENANCE COST*
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T««
                                          HID U.UOM FLOW KATI - H>
                                         PEEP SLUOQE FLOW RATE - Htm/m.
     •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
      (multiply value shown on this figure by 1.193)
     Source: USEPA 1982a
                                           10-92
-------
             FIGURE 10-32.   THE THREE BASIC STAGES OF A BELT PRESS
 CHEMICAL
CONDITIONAL
  STAGE
       POLYELECTROLITE
         SOLUTION
GRAVITY
DRAINAGE
 STAGE
                                              COMPRESSION
                                              DEWATERING
                                                 STAGE
SLUDGE•
    CONDITIONED
    SLUDGE
                                                         WASH WATER
 Source: USEPA, 1979
      A vacuum filter consists of a horizontal  cylindrical  drum which rotates
 partially submerged in a vat of sludge (Figure 10-33).   The drum is covered
 with a continuous belt of fabric or wire mesh.   A vacuum is applied to the
 inside of the drum by means of a connection within  a central trunion.   The
 vacuum causes liquid in the vat to be forced  through the filter medium leaving
 wet  solids adhering to the outer surface.  As  the drum  continues to rotate, it
 passes from the cake forming zone to a drying  zone,  and finally to a cake
 discharge zone where the sludge cake is removed  from the media (Metealf and
 Eddy,  1979;  USEPA, 1982).

      Pressure filtration is used to describe  a category of filters in which
 rigid  individual filtration chambers are operated in parallel  under relatively
 high pressure.  The filter press (Figure 10-34),  the most  common represen-
 tative of the group consists of vertical plates  that are held  rigidly in a
 frame  and are pressed together by a large screw  jack or hydraulic cylinder as
 shown  in  Figure 10-34.   The liquid to be filtered enters the cavity formed by
 the  frame.   Pressed against this hollow frame  are perforated metal plates
 covered with fabric filter medium.  The plate  operates  on  a cycle which
 includes  filling, pressing, cake removal, media  washing, and press closing
 (USEPA, 1982a and USEPA,  1979).   As the liquid flows through the filter
                                      10-93
-------
                      FIGURE 10-33.
                ROTARY VACUUM FILTER
            CLOTH CAULKING
                    STRIPS -
    AUTOMATIC VALVE
DRUM



 FILTRATE PIPING


   CAKE SCRAPER
                                          SLURRY AGITATOR

                                         VAT
        AIR BLOW-BACK LINE
                             SLURRY FEED
Source: USEPA, 1979
                          10-94
-------
                                              FIGURE 10-34.
FILTER  PRESS (ILLUSTRATIVE CROSS-SECTIONAL VIEW OF ONE RECTANGULAR CHAMBER)
                 Perforated Backing Plate
              Fabric Filter Medium
                                                                           Inlet Liquid to be
                                                                                Filtered
                                                                       Fabric Filter Medium
            Solid Rectangular
               End Plate
                                                                      Entrapped Solids
                                                                   \
                                                                       Plates and Frames are Pressed
                                                                      Together During Filtration Cycle
                                                                      Rectangular Metal Plate
                        Filtered Liquid Outlet
                                                              Rectangular Frame
              When the cavity formed between plates A and C is filled with solids, the plates are separated.
              The solids are than removed and the medium is washed clean.
              The plates are than pressed together and filtration resumed.
              Source: De Renzo, 1978
                                                    10-95
-------
medium, solids are entrapped and buildup within the cavity until the cavity is
full.  The slurry is dewatered until no filtrate is produced.  The press is
then opened, the dewatered slurry is removed, the plates are cleaned, and the
cycle is repeated (De Renzo, 1978).  In certain applications, the filter media
is precoated with diatotnaceous earth, fly ash, or other filter aids to improve
performance.

     Diaphragm filters are specially designed filter presses.  Instead of the
conventional plate and frame unit in which constant pumping pressure is used
to force the filtrate through the cloth, diaphragm filters combine an initial
pumping followed by a squeezing cycle that can reduce the cost and process
time.
               b.  Applications/Limitations


     Filtration can be used to dewater solids over a wide range of solids
concentrations and particle sizes.  Effectiveness for a particular application
depends on the type of filter, the particle size distribution, and the solids
concentrations.  For dewatering of municipal sludges where considerable
performance data is available, typical ranges for solids content and solids
removal or capture are as follows (USEPA, 1979; USEPA, 1982; Metcalf and Eddy,
1979):

                             SolidsContent (%)    Solids Capture(%)

Belt Press Filtration        15 to 45              85 to 95

Vacuum Rotary Filtration     15 to 35 or 40        88 to 95

Pressure Filter              30 to 50              98

     Manufacturers' data is also available on the performance of filtration
methods in dewatering coal slurries.  This data indicates that belt press and
filter press filtration are capable of producing a filter cake of up to 70 to
80 percent solids.  Also, tests conducted by Rexnord, Inc. demonstrated that
high density dredged materials can be dewatered to a cake solids concentration
of 70 percent using belt press filtration (Erickson and Hurst, 1983).

     Although the filter press achieves a dry filter cake and has the greatest
capacity for solids capture, there are a number of other factors which enter
into the decision to use a particular method of filtration.

     Filter presses generally require larger quantities of conditioning
chemicals than the other filtration methods.  They also have the highest
capital and operating cost and require the largest amount of space.
Replacement of filter media on a filter press is both expensive and time
consuming (USEPA, 1982a).
                                     10-96
-------
     Vacuum filtration is the most energy intensive of  the three methods and
the least effective in dewatering.  Another limitation  on the use of vacuum
filtration is that the incoming feed must have a solids content of at least
3 percent in order to achieve adequate cake formation (USEPA, 1982a).  A big
advantage to vacuum filtration is that because dewatering is accomplished by a
vacuum rather than by mechanical means, the hydraulic throughput is higher
than for the other filter types.  Vacuum filtration has an advantage over belt
press filtration in that it is easier to maintain and can operate effectively
even without optimum chemical conditioning.

     Recent advances in belt press filtration has made  this method nearly as
effective as pressure filtration.  The belt press filter also has the
advantage of being the least energy intensive of the filtration methods.  The
major limitation on the use of this method is that the  process is very
sensitive to incoming feed characteristics and chemical conditioning.  How-
ever, these limitations can be overcome to a certain extent; most belt presses
can be equipped with sensing devices which can be set to automatically shut
off feed flow in the case of underconditioning.  The feed characteristics can
be optimized by carefully prescreening the slurry to remove large objects and
fibrous material which can deteriorate the belt quickly (USEPA, 1982a).


               c.  Technology Selection/Evaluation


     Filtration appears to offer the most effective method for dewatering
slurries.  The processes are generally reliable, provided the slurries have
been properly prescreened and conditioned.   Filtration equipment, particularly
belt press and vacuum filtration, is well suited for inclusion in mobile
treatment systems.  Mobile systems are available from several manufacturers.
However, the maintenance requirements associated with filtration are
significant.  The filter cloth or belts must be periodically replaced and the
filter media periodically washed to remove contaminated solids.

     Despite their effectiveness in dewatering sludges, both the filtrate and
the dewatered sludge are likely to require further treatment prior to
disposal.  The water generated from washing of the filter media will also
require treatment.
               d.  Costs


     This section presents construction and O&M costs for diaphragm,
belt-press and vacuum filters.  It should be recognized that the curve for
construction cost is not capital cost.  The curve does not include costs for
special site work, general contractor overhead and profit, engineering, land,
legal, fiscal, and administrative work and interest during construction.
These cost items are all more directly related to the total cost of a project
rather than the cost of any one of the individual unit processes.  These costs
are therefore most appropriately added following cost summation of the


                                     10-97
-------
individual unit  processes,  if more than one unit  process  is required.
Typically, these costs  add  35 to 45 percent, depending  on project size and
complexity, to the  actual construction costs which  are  shown in the curves
(USEPA 1982a).

     Diaphragm filter press—Construction costs for diaphragm filter presses
ranging in size  from 1,200  to 15,505 ft  are shown  in Figure 10-35.  The
largest machine  manufactured is about 6,000 ft  ,  and multiple presses are
required for  larger press areas.  Construction  costs include the diaphragm
press, feed pump, pumps for the diaphragm and cloth washing, vacuum pumps an
air compressor and  receiver, lime and ferric chloride storage and feed
facilities and all  electrical and controls necessary for  complete automatic
operations.   Housing costs  are also included (USEPA, 1982a),

     Operation and  maintenance costs shown in Figures 10-36 and 10-37 were
developed for a  4 percent  feed of anaerobically digested  sludge, chemically
conditioned with 5  percent  ferric chloride and  a  20 percent lime.  Press
loading was 1.0  Ib/sq  ft/hr, without chemicals, and cake  discharge was taken
at 35 percent.   Press operation time was 19 hours per day, with the remaining
time dedicated to press cleanup and maintenance.


        FIGURE 10-35. CONSTRUCTION COST FOR DIAPHRAGM  FILTER PRESS*
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                               TOt»L FILTER PRESS AREA-ft2
                                 I 00         I 000

                                TOTAL flLTER PRESS AREA-m*
          •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1986
          (multiply value shown on this figure by 1.193)
          Source: USEPA, 1982a
                                       10-98
-------
     FIGURE 10-36.  DIAPHRAGM FILTER PRESS-LABOR AND TOTAL ANNUAL
                   OPERATION AND MAINTENANCE COST*
1
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                                  TOTAL I
 FIGURE 10-37. DIAPHRAGM FILTER PRESS-BUILDING ENERGY, PROCESS ENERGY
              AND MAINTENANCE MATERIAL REQUIREMENTS*
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•Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
 (multiply value shown on this figure by 1.193)
 Source: USEPA, 1982a
                                    10-99
-------
     Process energy  requirements are for the sludge  feed  pump,  the air pump
for inflating the  diaphragm,  and a vacuum pump  for removal  of liquid sludge
remaining in the  internal  piping prior to opening  the  press.   Energy is also
required to open  and close the press, for cloth washing,  and  for conditioning
chemical preparation and feed.  Building energy requirements  are based on 84
kwh/sq ft/yr.

     Maintenance  material  costs consist principally  (over 90  percent) of
replacement of diaphragms  and filter cloths.  Other  costs are for
miscellaneous equipment parts and for miscellaneous  electrical components.

     Labor required  is  for both operation and maintenance,  with the majority
of the labor devoted to operational requirements.  Labor  requirements are
based on operational experience of the manufacturer  (USEPA, 1982a).

     Belt Press Filters—Construction costs  are  for  belt  filter press
dewatering systems that include the belt press  unit, wash water pump,
conditioning tank, feed pump, polymer storage tank and pump,  belt conveyor,
and electrical control  panel.  Machines are  generally  sized using metric
dimensions and are rated on the basis of sludge  flow in gpm/m of belt width.
For mixtures of digested primary and secondary  sludges, a value of 50 gpm/m
belt width is a typical loading recommendation,  and  was used in the cost
development.  Higher loadings are possible  in some cases  if the sludge can be
easily dewatered  (USEPA, 1982a) .

     Estimated construction costs are presented in Figure 10-38 as a  function
of total  installed machine capacity.

           FIGURE 10-38. CONSTRUCTION COST OF A BELT FILTER  PRESS
                          <§  '

                                       -J-
                             Total Installed Machine Capacity-gpm
                              KO^0too
                             Total Installed Machine Capacity-liters/sec
            •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
             (multiply value shown on this figure by 1.193)
            Source: USEPA, 1982a
                                       10-100
-------
     Figures 10-39 and 10-40 present operation and maintenance costs  for  the
belt filter press.  Process energy requirements were developed from the total
connected horsepower for the belt drive unit, belt wash water pump,
conditioning tank, feed pump, polymer pump and tanks, belt conveyor,  and
electrical control panel.  A belt filter  loading of 50 gpm/m of machine width
was used in selecting unit sizes and determining power requirements.
Twenty-two hours of continuous operation  with 2 hour of downtime  for  routine
maintenance was assumed in calculating process energy requirements (USEPA,
1982a).

     Labor and maintenance requirements were estimated from information
provided by equipment manufacturers, as well as information from  plants
operating belt filter presses.  The maintenance material requirments  assume
the replacement of a set of belts every 6 months in continuous service.

     As operation and maintenance costs vary widely depending on  the  nature
and solids concentration of the sludge being processed, and adjustments to
these O&M requirements may have to be made on a case-by-case basis.
Conditioning chemical costs are not included in the total annual  O&M  cost
curve (USEPA, 1982a).

          Vacuum Filters—Costs for vacuum filter installations are presented
in Figure 10-41.  The costs include the vacuum filter, conditioning tank,
vacuum and filtrate pump assemblies, vacuum receiver, a short belt conveyor
for the dewatered sludge, feed sludge piping, lime and ferric chloride storage
and feed facilities, electrical controls, and necessary housing for the entire
assembly (USEPA, 1982a).

     Operation and Maintenance cost are shown in Figures 10-42 and 10-43.
Electrical energy curves are presented for bothprocess and building energy.
Process energy is for vacuum filer drumdrive, cake discharge roller, vacuum
and filtrate pumps, tank agitators,  and the dewatered sludge belt conveyor.
Process energy requirements were calculated for a sludge solids loading of
17 Ib dry 1.7 Ib/sq ft/hr.   Building sizes are based on conceptual layouts for
various total filter areas, and energy requirements are based on 34 kwh/sq
ft/yr of building/year (USEPA 1982a).

     Labor and maintenance material  requirements are based on opeating
experience at operating dewatering facilities.  Labor requirements are based
on 24 hour per day operation, and will have to be adjusted if filters are
operated for only one or two shifts  per day.   Maintenance material costs are
for periodic repair and replacement  of equipment.   Costs are not  inlcuded for
purchase of the lime or ferric chloride utilized for conditioning, since
chemcial requirements are highly variable from sludgeto sludge, and are not
generally a function of vacuum filter surface area (USEPA, 1982a).

     Table 10-16 shows capital and operating costs for a portable filter press
used for dewartering 20,000 gal/yr of 2 percent solids sludge.
                                     10-101
-------
               FIGURE 10-39. BELT FILTER PRESS-LABOR AND TOTAL ANNUAL
                            OPERATION AND MAINTENANCE COST*
I
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                                        FEED SLUOOt FLOW R*Tt -iltiri/»c.
FIGURE 10-40. BELT FILTER PRESS-BUILDING ENERGY, PROCESS ENERGY AND MAINTENANCE
              MATERIAL REQUIREMENTS*
1
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                                         FCCO tLUOQC FLOW MATE -
                                          o aLtwec FLOW MTC
               •Costs can be updated to $19% using ENR Construction Cost Indices for 1982 and 1985
                (multiply value shown on this figure by 1.193)
               Source: USEPA,1982a
                                          10-102
-------
         FIGURE 10-41. CONSTRUCTION COST FOR VACUUM FILTERS*
I
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< lOOOO
                                 TOTAL. FILTER *MCA -f«
                                 ror*;. FILTM AREA -» 2
                                                        1000
FIGURE 10-42. VACUUM FILTERS-LABOR AND TOTAL ANNUAL OPERATION
              AND MAINTENANCE COST*

7 -
K 3- S
i 3- J
S I- 2
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; f ?
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                                 TOTAL Ft-Ttll *«* -ft *
                                              Tic-
Tioo
                                 TOTAL nLTCM AftCA -
       "Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
        (multiply value shown on this figure by 1.193)
       Source: USEPA,1982a

                                       10-103
-------
            FIGURE 10-43. VACUUM FILTERS-BUILDING ENERGY, PROCESS ENERGY
                      AND MAINTENANCE MATERIAL REQUIREMENTS
I
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TOtAL riLTflt A«* -•*
             •Costs can be updated to $1985 using ENR Construction Cost Indices for 1982 and 1985
             (multiply value shown on this figure by 1.193)
             Source: USEPA, 1982a
10.3  Solidification/Stabilization
     Solidification  and  stabilization are terms which  are  used to describe
treatment systems which  accomplish one or more of  the  following objectives
(USEPA, 1982b):

     •  Improve waste  handling or other physical characteristics of the waste

     •  Decrease the surface  area across which transfer  or loss of contained
        pollutants can occur

     •  Limit  the solubility  or toxicity of hazardous  waste constituents.

     Solidification  is used to describe processes  where  these  results are
obtained primarily, but  not exclusively, by production of  a monolithic block
of waste with  high structural integrity.  The contaminants do  not necessarily
interact chemically with the  solidification reagents,  but  are  mechanically
                                      10-104
-------
   TABLE 10-16.   1985 CAPITAL AND OPERATING COSTS FOR PORTABLE FILTER PRESS*
The recurring annual costs for dewatering are as follows:
     Total labor time to transport, hook-up, operate and
     wash the press = 40 hrs/month.
     Filter cloth cost
     Disposal cost
                                          TOTAL
-  $ 5,990/yr
=  $ 1,040/yr
=  $ 6.032/yr
   $13,062/yr
The capital cost required is as follows:
     24" SPERRY HHC (or equal filter press (delivered)
         * polypropylene construction
         * 40" W x 102" L x 62" H
         * 4,000 Ibs. (dry)
   $15,600
     Trailer and mounting (including a sludge collection
     pan)                                                  =  $ 2,080
     Trailer mounted filtrate return pump                  =  $ 2,080
     Miscellaneous hoses and filterings                    =  $ 1 ,040
                                           TOTAL              $20,800
*Costs updated to $1985 using 1983 and 1985 ENR construction cost indices.
Source:  Moore, Gardner and Assoc., Inc. 1983
                                     10-105
-------
     locked within the solidified matrix.  Contaminant loss is minimized by
reducing the surface area.  Stabilization methods usually involve the addition
of materials which limit the solubility or mobility of waste constituents even
though the physical handling characteristics of the waste may not be improved
(USEPA, 1982b; Cullinane and Jones, 1985).  Methods involving combinations of
solidification and stabilization techniques are often used.

     Solidification/stabilization methods can be categorized as follows:

     •  Cement solidification
     •  Silicate-based processes
     •  Sorbent materials
     •  Thermoplastic techniques
     •  Surface encapsulation

     •  Organic polymer processes

     •  Vitrification.

     Detailed discussions of solidification/stabilization methods can be found
in Guide to the Disposal of Chemically Stabilized and Solidified Waste and
Technical Handbook for Solidification/Stabilization of Hazardous Waste
(Cullinane and Jones, 1985).

     These documents should be consulted for detailed information on these
processes.  However, it should be noted that the state-of-the-art of
solidification/stabilization methods is advancing rapidly.  Many manufacturers
are marketing processes which involve the use of various combinations of
alkaline earth materials (e.g., lime, cement kiln dust, silicaceous materials,
cement) often together with organic polymers and proprietary chemicals.

     10.3.1  Cement-Based Solidification


          10.3.1.1  General Description


     This method involves mixing the wastes directly with Portland cement, a
very common construction material.  The waste is incorporated into the rigid
matrix of the hardened concrete.  Most solidification is done with Type I
Portland cement, but Types II and V can be used for sulfate or sulfite wastes.
This method physically or chemically solidifies the wastes, depending upon
waste characteristics (USEPA, 1982b).  The end product may be a standing
monolithic solid or may have a crumbly, soil-like consistency, depending upon
the amount of cement added.
                                     10-106
-------
          10.3.1.2  Applications/Limitations


     Most hazardous wastes slurried in water can be mixed directly with cement
and the suspended solids will be incorporated into the rigid matrix.  Although
cement can physically incorporate a broad range of waste types, most wastes
will not be chemially bound and are subject to leaching.

     Cement solidification is most suitable for immobilizing metals because at
the pH of the cement mixture, most multivalent cations are converted into
insoluble hydroxides or carbonates.  However, metal hydroxides and carbonates
are insoluble only over a narrow pH range and are subject to solubilization
and leaching in the presence of even midly acidic leaching solutions (e.g.,
rain).  Portland cement alone is also not effective in immobilizing organics.

     The end product of cement solidification will not be acceptable for
disposal without secondary containment regardless of whether the wastes are
organic or inorganic in nature.  Another major disadvantage is that cement-
based solidification results in wastes that are twice the weight and volume of
the original material thereby increasing transportation and disposal costs
(USEPA, 1982b).  Because of these limitations, Portland cement is generally
used only as setting agent in other solidification processes particularly
silicate-based processes described in Section 10.3.2.

     Another problem with cement solidification is that certain wastes can
cause problems with the set, cure, and permanence of the cement waste solid
unless the wastes are pretreated.  Some of these incompatible wastes are
(USEPA, 1982b):

     •  Sodium salts of arsenate, borate, phosphate, iodate, and sulfide

     •  Salts of magnesium, tin, zinc, copper, and lead
     •  Organic matter
     •  Some silts and clays
     •  Coal or lignite.

     Major advantages to the use of cement include its low cost, and the use
of readily available mixing equipment.


          10.3.1.3  Implementation Considerations


     Since cement is primarily used as a setting agent in other solidification
processes, Sections (10.3.2 and 10.3.5) should be consulted for information
related to implementation.
                                     10-107
-------
          10.3.1.4  Costs
     Cement costs range from $60 to $90 per ton at the mill.  However, capital
expenditure and transportation will vary widely depending on the site and the
waste (see Section 10.3.2).  Cost information for specific wastes should be
obtained from vendors.  Vendors include:  Atcor Washington, Inc., Park Mall,
Peeksville, New York; and Chemfix, Inc., Kenner, Louisiana.
     10.3.2  Silicate-Based Processes


          10.3.2.1  General Description


     Silicate based processes refer to a very broad range of solidification/
stabilization methods which use a siliceous material together with lime,
cement, gypsum, and other suitable setting agents.  Extensive research is
currently underway on the use of siliceous compounds in solidification.  Many
of the available processes use proprietary additivies and claim to stabilize a
broad range of compounds from divalent metals to organic solvents.  The basic
reaction is between the silicate material and polyvalent metal ions.  The
silicate material which is added in the waste may be fly-ash, blast furnace
slag or other readily available pozzolanic materials.  Soluble silicates such
as sodium silicate or potassium silicate are also used.  The polyvalent metal
ions which act as initiators of silicate precipitation and/or gelation come
either from the waste solution, an added setting agent, or both. The setting
agent should have low solubility, and a large reserve capacity of metallic
ions so that it controls the reaction rate.  Portland cement and lime are most
commonly used because of their good availability.  However, gypsum, calcium
carbonate, and other compounds containing aluminum, iron, magnesium, etc. are
also suitable setting agents.  The solid which is formed in these processes
varies from a moist, clay-like material to a hard-dry solid similar in
appearance to concrete (Granlund and Hayes, undated).

     Some of the additives used in silicate based processes include (Cullinane
and Jones, 1985):

     •  Selected clays to absorb liquid and bind specific anions or cations

     •  Emulsifiers and surfactants which allow the incorporation of
        immiscible organic liquids

     •  Proprietary absorbents that selectively bind specific wastes.  These
        materials may include carbon, zeolite materials and cellulosic
        sorbents.
                                     10-108
-------
      There are a number of  silicate-based  processes which  are currently
 available or  in the  research  stages.  Manufacturers'  claim differ  signif-
 icantly  in terms of  the capabilities of  these  processes  for stabilizing
 different waste constituents.

      The Chemfix process  uses  soluble silicates with  cement as  the setting
 agent.   Research data  shows that  the process can  stabilize sludges containing
 high  concentrations  of heavy metals even under very acidic conditions
 (Spencer, Reifsnyder,  and Falcone, 1982).

      The Envirosafe  I  process  uses fly ash  as  the  source of silicates  and lime
 as  the alkaline earth  material.   This method has been shown to  stabilize oil
 bearing  sludge (49%  oil and grease) and  neutralize inorganic metal sludge.
 Success  was demonstrated by use of compressive strength  tests (using ASTM
 methods) and  leaching  tests (Smith and Zenobia, 1982).

      The DCM  cement  shale silicate process  is  a proprietary process formulated
 by  Delaware Custom Material,  Inc., State College, PA.  It  involves use of
 cement,  an emulsifier  for oily wastes, and  sodium  silicate.  Testing by
 Brookhaven National  Laboratories  showed  that the process could  stabilize oily
 wastes with up to a  30 percent volumetric  loading  (Clark,  Colombo,  and
 Neilson, 1982).  Manufacturers claim that  the  process can  be used  to solidify
 wastes containing acids,  organic  solvents  and  oils (Hayes  and Granlund,
 undated).

      PQ  Corporation  of Lafayette  Hill, Pennsylvania,  has done extensive
 research on the use  of silicates.  Their research describes successful
 stabilization of a mixed heavy metal/organic sludge;  a waste containing high
 levels of organics and petroleum  by-products;  and a waste  containing organic
 solvents using modifications of the process which involves the  use of  sodium
 silicates (Spencer,  Reifsnyder, and Falcone, 1982).


          10.3.2.2   Applications/Limitations
     There is considerable research data to suggest that silicates used
together with lime, cement or other setting agents can stabilize a wide range
of materials including metals, waste oil and solvents.  However, the
feasibility of using silicates for any application must be determined on a
site-specific basis particularly in view of the large number of additives and
different sources of silicates which may be used.  Soluble silicates such as
sodium and potassium silicate are generally more effective than fly ash, blast
furnace slag, etc.

     There is some data to suggest that lime-fly ash materials are less
durable and stable to leaching that cement fly ash materials (Cullinane and
Jones, 1985).

     Common problems with lime-fly ash and cement-fly ash materials relate to
interference in cementitious reactions that prevent bonding of materials.
                                     10-109
-------
Materials such as sodium borate, calcium sulfate, potassium dichromate and
carbohydrates can interfere with the formation of bonds between calcium
silicate and aluminum hydrates.  Oil and grease can also interfere with
bonding by coating waste particles (Cullinane and Jones, 1985).  However
several types of oily sludges have been stabilized with silicate based
processes.

     One of the major limitations with silicate based processes is that a
large amount of water which is not chemically bound will remain in the solid
after solidification.  In open air, the liquid will leach until it comes to
some equilibrium moisture content with the surrounding soil.  Because of this
water loss, the solidified product is likely to require secondary containment.

     Silicate-based processes can employ a wide range of materials, from those
which are cheap and readily available to highly specialized and costly
additives.

     The services of a qualified firm are generally needed to determine the
most appropriate formulation for a specific waste type.


          10.3.2.3  Implementation Considerations


     Commercial cement mixing and handling equipment can generally be used for
silicate-based processes.  Equipment requirements include chemical storage
hoppers, weight or volume-based chemical feed equipment, mixing equipment and
waste handling equipment.  Ribbon blenders and single and double shaft mixers
can be used for mixing.  A number of mobile, trailer mounted systems are
available.

     Silicate-based solidification can also be accomplished on a batch basis
in drums.  Equipment requirements include on-site chemical storage system,
chemical batching system, mixing system, and drum handling system.  One
company has developed a solidification kit for processing wastes in a drum.
The kit consists of a drum containing a disposable mixer blade with the shaft
held by bearings welded to the inside of the lid and the bottom of the drum.
The upper end of the shaft is accessible through a bung in the lid for turning
with an external motor.  The cement can be added to the drum before it is
capped.  The liquid waste and silicate are added through bungs in the lid.  An
air driven motor is clamped to the drum lid to turn the mixer (Granlund and
Hayes, undated).

     Solidification can also be accomplished in-situ using a lagoon or mixing
pit.  This would involve the use of common construction machinery such as a
backhor or pull shovel to mix the waste and reagents.  However, the ability of
in-situ solidification to prevent leaching of contaminants would need to be
demonstrated on a case-by-case basis.
                                     10-110
-------
           10.3.2.4  Costs
     Table 10-17 provides estimated costs for silicate cement solidification
using three different mixing methods:  in-drum mixing, in-situ mixing and a
mobile cement mixing system.  In all cases it was assumed that 500,000 gallons
(2,850 tons) of wastes were solidified with 30 percent portland cement and 2
percent sodium silicate.  On-site disposal was assumed.  These costs are
intended mainly to show the relative cost of various mixing methods and the
proportion of total cost for reagents, equipment and labor.  It should be
emphasized that actual costs are highly waste-and site-specific and that
specific site and/or waste characteristics could change these cost estimates
by several fold.

     In-drum mixing is by far the most expensive alternative and requires the
greatest amount of labor and production time.  Because of the high cost,
in-drum mixing is limited to sites have highly toxic or incompatible wastes in
drums (Cullinane and Jones, 1985).

     The cost of in~situ mixing and mobile treatment are much more comparable.
All are quite sensitive to reagent cost since it typically makes up from 40 to
65% of the total cost.  The in-situ technique is the fastest and most
economical of the bulk methods because the wastes typically only have to be
handled once, or not at all if they are to be left in-place.  Labor and
equipment each make up less than 5% of the total treatment cost.  However,
in-situ mixing is the least reliable because of difficulties in accurate
reagent measurement and in getting uniform and/or complete mixing of wastes
and treatment reagents.  Mobile mixing plants, although giving excellent
mixing results and reasonably good production rates, require that both the
treated and untreated product be handled, thereby increasing the costs above
those for in-situ treatment (Cullinane and Jones, 1985).


     10.3.3  Sorbents
          10.3.3.1  General Description


     Sorbents include a variety of natural and synthetic solid materials which
are used to eliminate free liquid and improve the handling characteristics of
wastes.  Commonly used natural sorbent materials include flyash, kiln dust,
vermiculite, and bentonite.  Synthetic sorbent materials include activated
carbon which sorbs dissolved organics, Hazorb (product of Dow Chemical) which
sorbs water and organics and Locksorb (product of Radecca Corp.) which is
reportedly effective for all emulsions (Cullinane and Jones, 1985).
                                     10-111
-------
       TABLE 10-17. SUMMARY COMPARISON OF RELATIVE 1985 COST
                   OF STABILIZATION/SOLIDIFICATION ALTERNATIVES1
Parameter
In-drum
In-situ"
                                                       Plant Mixing
Pumpable
Unpumpable
Metering and
mixing efficiency
Processing days
required
Good
374
Fair
4
Excellent
10
Excellent
14
Cost/ton
Reagent
Labor and per diem
Equipment rental
Used drums
@ $11 /drum
Mobilization-
demobilization

Cost of treatment
process
Profit and
overhead (30%)
TOTAL COST/ TON


$ 24.46
(9%)*
61.09
(23%)
44.43
(17%)
57.69
(21%)
18.76
(7%)

$206.38
61.91
(23%)
$248.29


$21.27
(63%)
1.41
(4%)
1.43
(4%)
-
1.64
(5%)

$25.75
6.73
(23%)
$33.48


$21.27
(53%)
3.97
(10%)
4.07
(10%)
-
1.48
(4%)

$30,79
9.29
(23%)
$40.03


$21.27
(42%)
7.19
(14%)
7.82
(16%)
-
2.34
(5%)

$38.62
11.59
(23%)
$50.21

*% of total cost/ton  for  that alternative.
 Costs updated from 1983  costs using  1985 ENR  Index.
2
 Assumed 49 gallons of untreated waste  per  drum  and  an  average  processing rate
 of 4.5 drums per hour.
 Assumed wastes would be  mixed by backhoe with a lagoon and  left  there.
 Remedial Action is located  200 miles from  its nearest  equipment.
4                                 .                        3
 Assumed pumpable sludge  had a~daily  throughput  of  250  yd and  the unputnpable
 sludge a throughput  of 180  yd /day.   Remedial Action  is assumed  to be located
 200 miles from the nearest  equipment.

Source: Cullinane and Jones, 1985
                                  10-112
-------
           10.3.3.2  Applications/Lira itations


      Sorbents are widely used to remove free  liquid and  improve waste
handling.  Some sorbents have been used to limit the escape of volatile
organic compounds.  They may also be useful in waste containment when  they
modify the chemical environment and maintain  the pH and  redox potential  to
limit the  solubility of wastes (Cullinane and Jones, 1985).  Although  sorbents
prevent drainage of free water, they do not necessarily  prevent leaching of
waste constituents and secondary containment  is generally required.


           10.3.3.3  Implementation Considerations


      The quantity of sorbent material necessary for removing free  liquid
varies widely depending on the nature of the  liquid phase, the solids  content
of  the wate, the moisture level in the sorbent, and the  availability of  any
chemical reactions that take up liquids during reaction.  It is generally
necessary  to determine the quantity of sorbent needed on a case-specific
basis .

     Equipment requirements for addition and mixing of sorbents are simple.
Any of the mixing methods described in Section 10.3.2.3  can be used.


      10.3.4  Thermoplastic Solidification


           10.3.4.1  General Description


     Thermoplastic solidification involves sealing wastes in a matrix  such as
asphalt bitumen, paraffin, or polyethylene.  The waste is dried, heated, and
dispensed through a heated plastic matrix.  The mixture  is then cooled to
form a rigid but deformable solid.  Bitumen solidification is the most widely
used of the thermoplastic techniques.


          10.3.4.2  Applications/Limitation


     Thermoplastic solidification involving the use of an asphalt binder is
most suitable for heavy metal or electroplating wastes.  Relative to the
cement solidification, the increase in volume is significantly less and the
rate of leaching significantly lower.   Also, thermoplastics are little
affected by either water or microbial attack.
                                     10-113
-------
     There are a number of waste types which are incompatible with thermo-
plastic solidification.  Oxidizers such as perchlorates or nitrates can react
with many of the solidification materials to cause an explosion.  Some
solvents and greases can cause asphalt materials to soften and never become
rigid.  Xylene and toluene diffuse quite rapidly through asphalt.  Salts that
partially dehydrate at elevated temperatures can be a problem.  Sodium sulfate
hydrate, for example, will loose some water during asphalt incorpoation and if
the waste asphalt mix containing the partially dehydrated salt is soaked in
water, the mass will swell and crack due to rehydration.  This can be avoided
by eliminating easily dehydrated salts or coating the outside of the waste/
asphalt mass with pure asphalt.  Chelating and complelxing agents (cyanides
and ammonium) can cause problems with containment of heavy metals (Cullinane
and Jones, 1985) .

     High equipment and energy costs are principal disadvantages of therm-
oplastic solidification.  Another problem is that the plasticity of the
matrix-waste mixture generally require that containers be provided for
transportation and disposal of materials which greatly increases the cost.

     Certain wastes, such as tetraborates, and iron and aluminum salts can
cause premature  solidification and plug up the mixing machinery (USEPA,
1982b).
          10.3.4.3  Implementation Considerations


     Thermoplastic solidification requires specialty equipment and highly
trained operators to heat and mix the wastes and solidifier.  The common range
of operating temperatures is 130° to 230°C.  The energy intensity of the
operation is increased by the requirement that the wastes be thoroughly dried
before solidification.


          10.3.4.4  Costs
     Cost data for thermoplastic solidification outside of the nuclear indus-
try is not readily available.  Wernen and Pfleudern Corporation has developed
an asphalt binder based process called the Volume Reduction and Solidification
System; solidification costs for non-radioactive materials are estimated at
$20 to $70 per ton.  This cost includes secondary containment but not final
transport and disposal (Doyle, 1980).
                                     10-114
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     10.3.5  Surface Microencapsulation


          10.3.5.1  General Description


     Surface encapsulation describes those methods which physically micro-
encapsulate wastes by sealing them in an organic binder or resin.

     Surface encapsulation can be accomplished using a variety of approaches.
Three methods which have been the subject of considerable research are
described briefly below:

     One process developed by Environmental Protection Polymers involves the
use of 1,2-polybutadiene and polyethylene (PE) to produce a microencapsulated
waste block onto which a high density polyethylene (HOPE) jacked is fused.
The 1,2-polybutadiene is mixed with particulated waste which yields, after
solvent evaporation, free flowing dry resin-coated particulates.  The
resulting polymers are resistent to oxidative and hydrolytic degradation and
to permeation by water.  The next step involves formation of a block of the
polybutadiene/waste mixture.  Powdered, high density PE is grafted chemically
onto the polymer backbone to provide a final matrix with ductile qualities.
Various combinations of the two resins (polybutadiene and PE) permit tailoring
of the matrix's mechanical properties without reduction of system stability
when exposed to severe chemical stress.  In the final step, a 1/4 inch thick
HDPE jacket is mechanically and chemically locked to the surface of the micro-
encapsulated waste (Lubowitz and Wiles, 1981).

     Another encapsulation method developed by Environmental Protection
Polymers involves a much simpler approach.  Contaminated soils or sludges are
loaded into a high density polyethylene overpack.  A portable welding
apparatus developed by Environmental Protection Polymers is then used to spin
weld a lid onto the container thereby forming a seam free encapsulate.

     A third surface encapsulation method involves use of an organic binder to
seal a cement-solidified mass.  United States Gypsum Company manufacturers a
product called Envirostone Cement which is a special blend of high-grade
polymer modified-gypsum cement.  Emulsifiers and ion exchange resins may be
added along with the gypsum cement which hydrates to form a freestanding mass.
A proprietary organic binder is used to seal the solified mass (United States
Gypsum Co., 1982).  The process can be used to stabilize both organic and
inorganc wastes.  It has been shown to effectively immobilize waste oil
present at concentration as high as 36 volume percent (Clark, Colombo, and
Neilson, 1982).   The volume of waste is smaller than that obtained with cement
solidification alone.
          10.3.5.2  Applications/Limitations

     The major advantage of encapsulation processes so far as research shows
is that the waste material is completely isolated from leaching solutions.
                                     10-115
-------
These methods can be used for both organic and inorganic waste constituents.
However, each of the available encapsulation processes are quite unique and
the feasibility must be determined on a case-specific basis.

     Other advantages associated with hazardous waste encapsulation include
(USEPA, 1982b):

     •  The cubic and cylindrical encapsulates allow for efficient space
        utilization during transport, storage, and disposal

     •  The hazard of accidental spills during transport is eliminated

     •  Materials used for encapsulation are commercially available, very
        stable chemically, nonbiodegradable, mechanically tough, and flexible

     •  Encapsulated waste materials can withstand the mechanical and chemical
        stresses of a wide range of disposal schemes (landfill, disposal in
        salt formations, ocean disposal).

     The major disadvantages associated with encapsulation techniques include:

     •  Binding resins required for agglomeration/encapsulation (high density
        polyethylene; polybutadiene) are relatively expensive

     •  The processes are energy intensive and relatively costly

     •  Skilled labor is required to operate molding and fusing equipment.
          10.3.5.3  Costs


     Environmental Protection Polymers has estimated that the cost of the
polybutadiene/HDPE microencapsulation method will be approximately $90/ton.
Encapsulation in the seam-free HDPE overpack is approximately $50 to $70 for a
80 gallon drum load (Lubowitz, H., Environmental Protection Polymers, personal
communication October 13 and 14, 1983).


     10.3.6  Vitrification


          10.3.6.1  General Description
     Vitrification of wastes involves combining the wastes with molten glass
at a temperature of 1,350°C or greater.  However, the encapsulation might be
done at temperatures significantly below 1,350°C (a simple glass polymer such
as boric acid can be poured at 850°C).  This melt is then cooled into a
stable, noncrystalline solid (USEPA., 1982b) .
                                     10-116
-------
           10.3.6.2  Applications/Lira itations


     This  process is quite costly and so has been restricted to radioactive or
very highly  toxic wastes.  To be considered for vitrification, the wastes
should be  either stable or totally destroyed at the process temperature.

     Of all  the common solidification methods, vitrification offers  the
greatest degree of containment.  Most resultant solids have an extremely low
leach rate.   Some glasses, such as borate-based glasses, have high leach rates
and exhibit  some water solubility.  The high energy demand and requirements
for specialized equipment and trained personnel greatly limit the use of this
method.
           10.3.6.3  Implementation Considerations
     Classification of wastes is an extremely energy intensive operation and
requires sophisticated machinery and high trained personnel.
          10.3.6.4  Cost


     No cost information was available for glassification.


     10.3.7  Technology Selection/Evaluation


     Evaluation of the technical feasibility and effectiveness of
stabilization/solidification methods must be determined on a case-by-case
basis.  Commercial firms specializing in these processes should be consulted
whenever solidification/stabilization is being considered.  Samples of the
solidified product will need to be subjected to extensive leaching tests
unless a reliable, effective means of secondary containment is to be used.  It
should be noted that secondary containment is recommended with most of the
previously described methods (except microencapsulation and glassification for
some waste types).  Similarly, where the end product is intended to be a
monolithic block, samples must be subjected to compressive strength tests.

     Solidification/stabilization methods run the gamut from those which use
simple, safe, readily available equipment (cement and most silicate-based
processes) to those which require highly sophisticated, costly, and
specialized equipment (e.g., glassification and thermoplastic techniques).
Use of these high technology processes should be limited to wastes which
cannot be treated cost-effectively using any other methods.   Regardless of the
simplicity of some of the equipment, professionals trained in these processes
should be consulted since formulations including proprietary additives are
very waste specific.
                                     10-117
-------
10.4  Gaseous Waste Treatment
     Gaseous wastes may be present at hazardous waste sites as a result of
bulk gas disposal in containers, volatilization of organic liquids,  byproducts
of waste decomposition, or byproducts of treatment or other on-site  processes.
Once captured and collected, gaseous wastes can be treated thermally to render
contaminants less hazardous or treated physically or chemically to remove and
concentrate contaminants.  The following three categories of gaseous waste
treatment are described in this section:

     •  Incineration

     •  Flaring
     •  Adsorption.


     10.4.1  Flaring


          10.4.1.1  General Description


     Combustion is a chemical reaction that thermally oxidizes a substance
into products that generally include ash, gases, water vapor, and heat.
Flaring is a special category of combustion where wastes are exposed to an
open flame and no special features are employed to control temperatures or
time of combustion.  Supplementary fuels may be needed to sustain continuous
combustion.


          10.4.1.2  Applications/Limitations


     Flares are commonly used in the oil and gas industry to dispose of waste
gases and fumes at refineries; at sewage treatment plants to dispose of
digestor gas; and at sanitary landfills to dispose of landfill gas.   Although
flares provide sufficient destruction of contaminants for conventional
applications, destruction removal efficiencies (DREs) required by current
environmental regulations for thermal destruction of hazardous wastes are
generally too stringent to be met by flaring.  Exceptions may be gaseous waste
streams consisting of relatively simple hydrocarbons (emissions from fuel
tanks, landfill methane gas, etc.).

     Supplemental fuel is required to sustain a flame with gases of  low
heating value.  Gases with heating values as low as the low hundreds of Btu's
per cubic foot can sustain a flame (natural gas has a heating value  of approx-
imatley 1,000 Btu's per cubic foot).

     Flame sensors, pilot flames, automatic sparkers, and alarms are often
used to sense loss of flame, attempt reignition, and alert operators to system
                                     10-118
-------
performance problems.  Shields  can  be  placed around floors to serve as
windbreaks for containing  and preventing "blowing out" of the flame.

     The flow rate dictates  the diameter and height of the flare and  the
number of flares to be employed.  The  flare must be designed such that the
flame is largely contained within the  body of the flare for safety reasons  and
to allow adequate mixing of  gas and air.  The oxygen content of the gas
influences the air/gas ratio that is sought in the combustion area of the
flare.
          10.4.1.3  Costs

     Purchase costs of  flares  depend primarily on the waste-gas  flowrate,  and
secondarily on design and  elevation.  Costs in dollars for flowrates between
1,000 and 100,000 Ib/h  are given in Figure 10-44.  Costs include ladders,
platforms, knockout drums  with seals,  and stacks high enough to  ensure
grade-level radiation no greater than 1,500 Btu/(h)(ft ).  Costs described in
Figure 10-44 refers to  self-supporting type elevated flares (approximately 40
feet high).  Costs for  elevated flares supported by guyed wires  (nominally 100
feet tall) range from 30 percent higher (than the self-supporting type)  at
250,000-lb/h flowrates,  to 80  percent higher at 2,500-lb/h flowrates.

     Operating costs for flares are high because of the substantial quantity
of natural gas and steam (in the smokeless type) consumed.  If the waste-gas
must be driven, fan power  costs for overcoming pressure drops may also be
                FIGURE 10-44. PURCHASE COSTS OF ELEVATED FLARES
                     10*
                     103
                       103          104           105
                                  Waste-gas flowrate, Ib/h
                               (high Btu-ethylene)
                               (low Btu-60 Btu/ft3)
                   Source: Vatavuk  and Neveril, 1983
                                     10-119
-------
high.  This  pressure drop depends on the size of the flare, knockout  drum,
puiping  and  stack height, with the maximum allowable pressure drop being
approximately  60  in.  HO.

     Elevated  flares require supplemental fuel, (in addition to gas for pilots
and purging) when a  low-Btu gas is being burned.  The supplemental fuel
(natural  gas)  required  is plotted against waste-gas flowrate in Figure 10-45.
This graph is  based  on  an 880-h/yr operating factor, for gas flowrates in the
range of  1,000 to 250,000 Ib/h.

     Steam consumption  for smokeless flares (or others requiring steam
injection) can be  estimated at  0.6 Ib/lb of waste-gas.
          10.4.1.4  Technology  Selection/Evaluation
     Flaring systems, by virtue of  their  relative lack of controllability, are
generally considered to perform inconsistently.    They are relatively simple
to both fabricate and install.  Conventional  steel plate, pipe, and welding
are employed in fabrication.

     When properly designed and operated,  flares  pose no unusual safety
impacts to operators or others.  The  presence  of  a visible flame is sometimes
considered by the public to be a nuisance.

       FIGURE 10-45. NATURAL GAS REQUIREMENTS FOR ELEVATED FLARES
            S
              10*
               1Q3
                                             'Elevated
                1Q2          103          10*          106
                               Natural gas, million Btu/yr

            Source: Vatavuk and Neveril, 1983
                                     10-120
-------
     Properly designed flaring systems operate automatically.  The most basic
design of flaring requires tnonical ignition.  Pilot flames, sensors, and
igniters may require regular maintenance.  Monitoring of air quality local  to
the flame is advisable to ensure that adequate treatment is being afforded.
     10.4.2  Adsorption


          10.4.2.1  General Description
     Adsorption is the adherence of one substance to the surface of another by
physical and chemical processes.  Treatment of wastestreams by adsorption is
essentially a process of transferring and concentrating contaminants (the
adsorbate) from one medium (liquid or gas) to another (the adsorbent).  The
most commonly used adsorbent is activated carbon; generally, the granular form
(GAG) is used to treat gaseous wastes.  Other adsorbents are specially
manufactured resins.

     Activated carbon is a highly porous material.  Adsorption takes place on
the walls of the pores because of an imbalance of forces on the atoms of the
walls.  The adsorption of molecules onto the wall surfaces serves to balance
the forces (Calgon Corp., undated).  Adsorption onto resins occurs in a
similar fashion.

     Adsorption gas treatment systems consist of containerized beds of
adsorbent.  Large and highly permeable void spaces between relatively large
GAG particles or pellets (nominal size of several millimeters) allow the
contaminated medium to flow through the bed, contacting the particles and
allowing adsorption to take place.  The treated medium leaves the bed with
reduced concentrations of adsorbate until the adsorbent has reached capacity.
Once adsorbents have reached capacity, little or no further adsorption occurs
and some contaminants can be released back into the medium (desorption) and
actually increase contaminant concentrations.

     Adsorbents at capacity can be disposed of in appropriate landfills,
incinerated, or can be regenerated, driving off the adsorbate and allowing
reuse of the adsorbent for treatment.  GAG is regenerated by heating in a
reduced-pressure atmosphere (Calgon Corp, undated).   Resins are regenerated by
washing with appropriate solvents (Kiang and Metry,  1982).   The adsorbate can
be recovered and reused (solvents, for example)  from the regeneration process.

     Multiple bed vessels are often required to allow adequate contact time
and/or to optimize the frequency of adsorbent changeover or regeneration.
Partial or total redundant capacity is often provided by extra bed vessels to
allow continuous operation during changeover or regeneration.
                                     10-121
-------
          10.4.2.3  Applications/Limitations


     Carbon adsorption is generally accepted for use in controlling volatile
hydrocarbons; organic-related emissions; certain sulfur-related emissions such
as hydrogen-sulfide; mercury; vinyl chloride; most halogenatd organics; and
radioactive materials such as iodine, krypton, and xenon.  Carbon adsorption
can also control oxides of sulfur and nitrogen and carbon monoxide (Calgon
Corp., undated).

     Resins are capable of removing most organic contaminants from water and
are also applicable to removal of organics from gaseous streams.  However,
resins are not widely used for gaseous waste treatment.

     Adsorption is widely used in industry for air pollution and odor control,
often in association with solvent recovery and reuse systems.  Generally, GAG
acts as an accumulator of organic contaminants until the bed is saturated.
Hot gases are passed through the bed to desorb the organics which are
condensed and recovered or are incinerated (Calgon Corp., undated).

     Monitoring of gas flowrate and influent and discharge adsorbate concen-
trations are needed to determine changeover/regeneration schedules.  Automatic
monitors and microprocessors may be warranted for highly complex and variable
systems.  Alarms and/or shut-down controls may also be warranted for complex
systems or in sensitive or populated areas.


     10.4.3  Technology Selection/Evaluation


     Adsorption techniques are well-established for removal of organic
compounds and some inorganic compounds  from gaseous streams.  Adsorption is
highly reliable provided that adsorbate and adsorbent are properly matched,
sufficient contact time is allowed, and the adsorbent is regenerated or
replaced before saturation (and desorption) is reached.  Many adsorption
systems are prepackaged and can be quickly installed and placed into operation
by contractors, suppliers, or manufacturers.  Specially designed systems
employ off-the-shelf towers, blowers, and other equipment, and require
additional installation time.

     Operation of properly designed adsorption gas treatment systems is
essentially as automatic as the gas delivery system although manual or special
automatic adjustments may be warranted  for highly variable flows or adsorbate
concentrations.  Changeover or regeneration of the adsorbent bed must be
conductd on a predetermined basis to ensure continuous effective treatment.
                                     10-122
-------
10.5  Thermal Destruction of Hazardous Wastes


     Thermal destruction is a treatment method which uses high temperature
oxidation under controlled conditions to degrade a substance into products
that generally include C0~, H-0 vapor, SO-, NO , HCl gases and ash.  The
hazardous products of the thermal destruction/incineration such as partic-
ulates, SO,,, NO ,  HCl, and products of incomplete combustion require air
pollution control  equipment to prevent release of undesirable species into the
atmosphere.  Thermal destruction methods can be used to destroy organic
contaminants in liquid, gaseous and solid waste streams.

     The most common incineration technologies applicable to hazardous wastes
include:

     •  Liquid injection

     •  Rotary kiln
     •  Fluidized  bed

     •  Multiple hearth

     The operating principles and general applications of these methods are
summarized in Table 10-18.  Mobile incinerators, at sea incinerators and
coincineration commonly employ these technologies.

     Emerging technologies for the thermal destruction of wastes include
(Monsanto Research Corp.; 1981, Keitz and Lee, 1983; Lee, 1983; State of
California, 1981):

     •  Molten salt

     •  Wet air oxidation
     •  Plasma arch torch

     •  Circulating bed
     •  High temperature fluid wall
     •  Pyrolysis
     •  Supercritical water

     •  Advanced electric reactor
     •  Vertical tube reactor.
                                     10-123
-------


















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      10.5.1   Liquid  Injection
           10.5.1.1   General Description
     A liquid  incineration system consists of a single or double refractory-
lined  combustion  chamber and a series of atomizing nozzles.  Two chamber
systems are  more  common.  The primary chamber is usually a burner where
combustible  liquid  and gaseous wastes are introduced.  Noncombustible liquid
and  gaseous  wastes  are introduced downstream of the burner in the secondary
chamber.   A  schematic  diagram of a two-stage system is shown in Figure 10-46.
Single chamber incinerators are used for systems handling only combustible
wases  (Kiang and  Metry,  1982).
                                FIGURE 10-46.
                  LIQUID INJECTION INCINERATION SYSTEM
                                                       FLUE GAS
                                     FEED
                                STEAM WATER
                WATER

        LIQUID WASTE
             FUEL
              AIR
                                                             SALT
                                                             SOLUTION
     Source: Kiang and Metry, 1982
     The most popular  liquid  injection  incinerators are horizontally and
vertically fired units.  A  liquid  waste has  to be converted into a gas before
combustion.  The liquid  is  atomized  passing  through the burner nozzles while
entering the combustor.  This  is necessary to ensure complete evaporation and
oxidation.  If viscosity precludes atomization,  mixing and heating or other
means should be applied  prior  to atomization to reduce waste viscosity.

     The operating temperatures vary from 1300 to 3,000°F, with the most
common temperature being about  1600°F.   Residence times vary from less than
0.5 seconds to 2 seconds (Lee, Keitz, and Vogel,  1982; State of California,

                                      10-125
-------
1981). The process usually requires 20 to 60% excess air to ensure complete
combustion.
          10.5.1.2  Application Limitations

     Liquid injection can be used to destroy virtually any pumpable waste or
gas.  These units have been used in the destruction of PCBs,  solvents, still
and reactor bottoms, polymer wastes, and pesticides (State of California,
1981).  Unlikely candidates for destruction include heavy metal wastes and
other wastes high in inorganics.  It does not have a need for a continuous ash
removal system other than for pollution control (Monsanto Research Corp.,
1981).

     Liquid incinerators have no moving parts and require the least
maintenance of all types of incinerators.  The major limitations of liquid
injection are its ability to incinerate only wastes which can be atomized in
the burner nozzle and the burner's susceptibility to clogging.  It also needs
a supplemental fuel.

     Liquid injection incinerators are highly sensitive to waste composition
and flow changes.  Therefore, storage and mixing tanks are necessary to ensure
a reasonably steady and homogenous waste flow (Kiang and Metry, 1982).


     10.5.2  Rotary Kiln


          10.5.2.1  General Description


     Rotary kilns are capable of handling a wide variety of solid and liquid
wastes.

     Rotary kiln incinerators are cylindrical, refractory-lined shells.  They
are fueled by natural gas, oil, or pulverized coal.  Most of the heating of
the waste is due to heat transfer with the combustion product gases and the
walls of the kiln.  The basic type of rotary kiln incinerator, illustrated in
Figure 10-47, consists of the kiln and an afterburner (Kiang and Metry, 1982).

     Wastes are injected into the kiln at the higher end and are passed
through the combusion zone as the kiln rotates.  The rotation creates
turbulence and improves combustion.  Rotary kilns often employ afterburners to
ensure complete combustion.  Most rotary kilns are equipped with wet scrubber
emission controls.

     The residence time and temperature depend upon combustion characteristics
of the waste.  Residence times can range from a few seconds to an hour or more
for bulk solids.  Combustion temperature range from 1500 to 3000°F.
                                     10-126
-------
          10.5.2.2  Application/Limitations
     Rotary kilns  are  capable of burning waste in any physical  form.   They can
incinerate solids  and  liquids independently or in combination and  can accept
waste feed without  any preparation (Monsanto, 1981).  Hazardous wastes which
have been treated  in rotary kilns include PCBs, tars, obsolete munitions,
polyvinyl chloride  wastes,  and bottoms from solvent reclamation operations
(State of California,  1981).
              FIGURE 10-47. ROTARY KILN INCINERATOR SCHEMATIC
                             OXIDATION
                             CHAMBER
                                               FLUE GAS
                                               SCRUBBER
         WASTE
         STORAGE
         HOPPER
                                                               ©
                                                                  STACK
L VA/ yy i



ASH /
REMOVAL
MECHANISM
J»
©

1 1

T ©
LIQUID



                                                HOLDING
                                                TANK
                                 LEGEND:
                                  1. INFLUENT WASTE
                                  2. COMBUSTION AIR
                                  3. FLUE GAS
                                  4. RESIDUALS
                                  5. SCRUBBER WATER
                                  6. FUEL


          Source: Ghassami, Yu, and Quinlivan, 1981



     Because of  their  ability to handle waste in any physical  forms,  and their

high incineration efficiency,  rotary kilns are the preferred method  for

treating mixed hazardous  solid residues (Lee, Keitz, and Vogel, 1982).


     The limitations of  rotary kilns include susceptibility to thermal shock,

the necessity for very careful maintenance,  need for additional air  due  to

leakage, high particulate loadings,  relatively low thermal efficiency, and a

high capital cost for  installation  (Monsanto Research Corp., 1981).
                                      10-127
-------
     10.5.3    Multiple Hearth
          10.5.3.1  General  Description
     A multiple hearth  incinerator  consists of a refractory lined steel  shell,
a rotating central shaft, a  series  of  solid flat hearths, a series of rabble
arms with teeth for each hearth,  an air  blower, waste feeding and ash removal
systems, and fuel burners mounted on the walls (Monsanto Research Corp.,
1981).  Figure 10-48  illustrates  the components of the.multiple hearth.   It
can also be equipped with an afterburner, liquid waste burners and side  ports
for tar injection.  Temperature in  the burning zone ranges from 1400 to  18008F
and residence time may  be very long.
          10.5.3.2  Applications/Limitations
     The multiple hearth  incinerator  can be used for the disposal of all  forms
of combustible industrial waste materials,  including sludges, tars, solids,
liquid and gases.  The  incinerator  is best  suited for hazardous sludge
destruction.  Solid waste often requires pretreatment such as shredding and
                  FIGURE 10-48. MULTIPLE HEARTH INCINCERATOR
                                AIR
                                                FLUE GAS
                WASH
                                                           WATER
                    All
 I IHCIHIRATOR
 |            ASH
ASB
                                                 SLURJtt
                             BLOW*
                Source: Kiang and Metry, 1982
                                      10-128
-------
sorting.  It can treat the same wastes as the rotary kiln provided  that
pretreatment of solid waste is applied.  The principal advantages of multiple
hearth incineration include high residence time for sludge and low  volatile
materials; ability to handle a variety of sludges; ability to evaporate  large
amounts of water; high fuel efficiency and the utilization of a variety  of
fuels.  The greatest disadvantages of the technology include susceptibility to
thermal shock; inability to handle wastes containing ash, which fuses  into
large rock-like structures, and wastes requiring very high temperatures.  Also
control of the firing of supplemental fuels is difficult.  The multiple  hearth
incinerator has high maintenance and operating costs (Monsanto Research  Corp.,
1981; State of California, 1981).  The operating cost may be reduced by
utilizing liquid or gaseous combustible wastes as secondary fuel (Monsanto
Research Corp., 1981).
     10.5.4  Fluidized Bed


          10.5.4.1  General Description


     The fluidized bed incinerator illustrated in Figure 10-49 consists of a
cylindircal vertical refractory lined vessel containing a bed of inert
granular material, usually sand on a perforated metal plate.  Combustion air
is introduced through a plenum at the bottom of the incinerator and rises
vertically fluidizing the bed and maintaining turbulent mixing of bed
particles.  Waste material is injected into the bed and combustion occurs
within the bubbling bed.  Heat is transferred from the bed into the injected
wastes.  Auxiliary fuel is usually injected into the bed.  Bed temperatures
vary from 1400 to 1600°F.  Since the mass of the heated, turbulent bed is much
greater than the mass of the waste, heat is rapidly transferred to the waste
materials; a residence time of a few seconds for gases and a few minutes for
liquids is sufficient for combustion (State of California, 1981).

     The residence time is long enough to allow the solid materials to become
small and light enough to be carried off as particulates.  Suspended fine
particulates are usually separated in a cyclone when exhaust gases pass
through air pollution control devices before being released into the
atmosphere.


          10.5.4.2  Applications/Limitations


     Fluidized bed incinerators are a relatively new design, presently being
applied for liquid, solid and gaseous combustible wastes.  The most typical
wastes treated in fluidized beds include slurries and sludges.  Some wastes
require pretreatment prior to entering the reactor.  The pretreatment may
involve drying, shredding and sorting.  The fluidized bed handles the same
waste that can be treated in the rotary kiln (Monsanto Research Corp., 1981).
                                     10-129
-------
                      FIGURE 10-49. FLUIDIZED BED INCINERATOR
                                                   FLUE
                                                   GAS
                    ASH
                        J • y/»< X'^f :•" v," ^."?~£st) f.
                      s^^nH'HrfiiiftfiimHiMi
                                                 FUEL




                                             BURNER

                                                 MAKE-UP SAND
                                                      WASTE
                                                     . AIR
                    Source: Kiang and Metry, 1982
     Fluidized beds  are  typically used for the disposal of municipal waste-
water treatment plant  sludges,  oil refinery waste, and pulp and paper mill
waste.  There is only  limited data on the use of fluidized bed for hazardous
waste incineration.  The technology has been used for pharmaceutical wastes,
phenolic wastes, and methyl methacrylate (State of California, 1981).

     It is particularly  well  suited for incineration of high-moisture wastes,
sludges and wastes containing large quantities of ash.  Because of the  low bed
temperature, the exhaust gases  usually contain low nitrogen oxides (Kiang and
Metry, 1982).

     The advantages  of the  fluidized bed incinerator include simple design,
minimal NO  formation, long  life of the incinerator, high efficiency,
sitnplicityxof operation, and  relatively low capital and maintenance costs.   It
also has the ability to  trap  some gases in the bed, reducing the need for and
the cost of an emission  control system.  The disadvantages include difficulty
in removing residual materials  from the bed, a relatively low throughput
capacity, the difficulty in  handling residues and ash from the bed and  the
                                      10-130
-------
relatively high operating costs (State of California, 1981; Monsanto Research
Corp., 1981).


     10.5.5  At-Sea Incineration, Mobile Incineration, and Coincineration


     At-sea incineration usually utilizes a liquid injection unit mounted on a
ship, to destroy hazardous waste far away from populated areas and shipping
lanes.  No acid gas pollutant removal system is applied.  The wastes treated
include toxic organochloride compounds, herbicides, and Agent Orange.  The
basic advantage of at-sea incinertaion is the distance from populated areas
and the high efficiency of combustion.  The disadvantages are problems with
monitoring an at-sea process, the danger of spills and the need to operate
on-shore auxiliary facilities.

     Mobile incineration has not been widely used yet but the demand for the
application of this technique grows with future bans on the landfill disposal
of certain wastes.  Existing mobile systems include liquid injection and
rotary kiln incinerators equipped with secondary combustion chambers and
environmental controls.  These mobile incinerators are capable of handling a
variety of wastes including PCBs, carbon tetrachloride, other hazardous wastes
and soils.  The primary advantage of the mobile incinerator is its ability to
treat on-site and thus eliminate the need for off-site transport of waste.
There is currently only limited experience with mobile incinerators.  Mobile
incinerators must meet all applicable state requirements which typically
include air emission permits.

     Coincineration is a process of using combustible wastes as supplemental
fuels in fossil fuel boilers or any type of incinerator (State of California,
1981; Monsanto Research Corp., 1981).  As a result of Coincineration, the
energy value of the waste is used to produce steam and the original form of
the waste is destroyed through combustion.  This incineration technique can be
implemented in any boiler where the parameters of combustion and feed make it
feasible.  The principal advantages of Coincineration include low capital
cost, and no need for the transport of on-site generated wastes.  Dis-
advantages include the possibility of damaging the boiler by some harmful
waste and the difficulty in obtaining high efficiency of combustion.


     10.5.6  Advanced Incineration Technologies


          10.5.6.1  Molten Salt
     The molten salt incinerator can be used for destruction of hazardous
liquids and solids.  In this method (illustrated in Figure 10-50) wastes
undergo catalytic destruction when they contact hot molten salt maintained at
a temperature between 1382 and 1832°F (Ross, 1984; Solsberg, Parent, and Ross,
1985).  Hot gases rise through the molten salt bath, pass through a secondary


                                     10-131
-------
         FIGURE 10-50. MOLTEN SALT INCINERATOR
         MOLTEN SALT COMBUSTOR SCHEMATIC
             LIQUID OR SOLID WASTE   x ATOMIZING
                              AIR
                 OFF
             DOWNCOMER
             METAL
             CONTAINMENT
             VESSEL
                                        SUPPORT
                                        STRUCTURE
INSULATED
ENCLOSURE
               SIMPLIFIED FLOW SCHEMATIC
               MOLTEN SALT DESTRUCTION
                                   SALT DISPOSAL
Source: Rockwell International, 1980
                         10-132
-------
reaction zone, and through an off-gas clean-up system before discharging to
the atmosphere (Kiang and Metry, 1982).  Supplemental fuel may be required
when wastes are not sufficiently combustible to maintain temperatures.

     Liquid, free-flowing powders, sludges, and shredded solid wastes can be
fed directly into the incinerator.  The technology has been demonstrated to be
highly effective for chlorinated hydrocarbons including PCB, chlorinated
solvents, and malathion (Kiang and Metry, 1982).  However, the process appears
to be sensitive to materials containing high ash content or high chlorine
content which must ultimately be removed in the purge system (Ross, 1984).


          10.5.6.2  Wet Air Oxidation
     Wet air oxidation involves aqueous phase oxidation of dissolved or
suspended organic substances at elevated temperatures and pressures.  The
temperature of the process is relatively low, 350-650°F, and the pressure
varies between 300-3000 PSI.  Figure 10-51 shows a simplified scheme of the
wet air oxidation process.

     The waste is pumped into the system by the high pressure pump and mixed
with air from the air compressor.  The mixture passes through a heat
exchanger, and then into the reactor where oxygen in the air reacts with
organic matter in the waste.  The oxidation is accompanied by a temperature
rise.  The gas and liquid phases are separated after the reactor, and the
liquid passes through the heat exchanger, heating the incoming material.  The
gas and liquid streams are discharged from the system through control valves.
The degree of oxidation is primarily a function of reaction temperature and
residence time.

     WAO is used primarily to treat concentrated waste streams containing
organic and oxidizable inorganic wastes.  It is generally selected for
treating or pretreating a waste stream which has a high COD/BOD,, ratio and is
not readily amenable to biological treatment.  It is also selected where it is
determined to be more cost-effective than incineration.  Waste streams for
which WAO is particularly applicable include concentrated streams containing
pesticides, herbicides or other complex organics which are not readily
biodegradable.


          10.5.6.3  Plasma Arc Torch
     Plasma arc torch may be used to destory either liquid or solid wastes by
pyrolyzing them into combustible gases in contact with a gas which has been
energized to its plasma state by an electrical discharge (see Figure 10-52).
The plasma gas temperature is about 90,000°F.  Wastes are atomized, ionized
                                     10-133
-------
                                  FIGURE 10-51.
                       FLOWSHEET OF WET AIR OXIDATION











WASTK.


STORAGE
TANK
l*^


\

/
****


GAS
SEPARATOR |
*"— T
^_
S-
?
" /S


*'• OXIDIZED
i^i x^ UT° ?
AIR r~\ £?\ 4 T
COMPRESSOR!^ 1 V HF 1

•t
o~
PUMP
^^T ^"^ *— IV-J
1 r














REACTOR




h-J

HEAT EXCHANGER
Source: Pradt, 1976
                                 FIGURE 10-52.
                     PLASMA REACTION VESSEL SCHEMATIC
                                                  r-
                    Source: Lee, Keitz and Vogel, 1982
                                          10-134
-------
and destroyed in contact with the plasma.  The advantages of this method are
possibilities of using the exiting gas as a fuel (after removal of halogens
and other contaminants in a scrubber), the lack of hazardous interim
combustion products, high efficiency  and the ability to be portable.  Costs
are not presently available (State of California, 1981).

          10.5.6.4  Circulating Bed Combustion (CBC)


     Circulating bed combustion is an outgrowth of conventional fluidized bed
incineration.  However, the fluid bed operates with higher velocities than
conventional fluid beds and it recirculates the fluidized material within the
system returning it back to the feed  section (Ross, 1984).  Figure 10-53
illustrates a CBC.

     The CBC is suitable for burning  solid, liquid, sludge or gaseous waste
streams.  The advantages of this incinerator are similar to those of a
conventional fluidized bed system with lower susceptibility to corrosion of
the boiler, a less complicated scrubbing system, close temperature control and
dry solid waste recovery.


          10.5.6.5  High Temperature Fluid Wall (HTFW)


     The high temperature fluid wall process quickly reduces organic wastes to
their elemental state in a very high temperature process (about 4000°F) (Keitz
and Vogel, 1982).  The process is carried out in a patented reactor which
consists of a tubular core of refractor material capable of emitting radiant
energy supplied by large electrodes in the jacket of the vessel.  During the
process, an inert gas is injected to coat the wall of the reactor and prevent
destruction from high temperatures.  A cross-section of a typical high-
temperature fluid wall reactor is shown in Figure 10-54.  HTFW has been used
to treat PCB contaminated earth and other wastes.  It ensures high destruction
efficiency, eliminates the formation of intermediate pyrolysis products but
requires some preparation of the feed material and it also incurs high energy
costs.
          10.5.6.6.  Pyrolysis


     Pyrolysis is the thermal conversion of organic material into solid,
liquid and gaseous components.  Pyrolysis takes place in an oxygen-deficient
atmosphere at temperatures from 900° to 1600°F.  The volatile organics
generated in the process are burned in a second stage fume incinerator at
temperatures of 1800 to 3000°F.  The two-stage process minimizes the volatil-
ization of inorganic components and ensures that inorganic.s, including heavy
metals, form an insoluble solid char residue.  The technology may be used for
the destruction of materials containing carbon, hydrogen and oxygen.
Pyrolysis can not handle wastes with nitrogen, sulfur, sodium contents.
                                     10-135
-------
          FIGURE 10-53. CIRCULATING BED COMBUSTOR
                                       PROCESS STEAM
                                         FOR HEATING
SUPERHEATED
   STEAM
  COMBUSTOR
  WASTES, FUEL
      AND
    ADDITIVES
      FEED
                                               QEN
                                                    t—  ELEC-
                                                      TRICITY
feri
J/%T I
HOT
CY-
LONEJ
••'•'/
...7





»
^^

1


X
EVAPORATIVE &
-"SECTION


*H2O





1 — |



DUST
COLLECTOR
                                                     EXHAUST
                                                       GAS
  AIR-KPO)))))))))))!
  Source: Ross, 1984
                             INERT
                             DUST^

                               TURNS LOW GRADE FUEL INTO POWER
FIGURE 10-54. CROSS-SECTION OF A TYPICAL HIGH-TEMPERATURE
                     FLUID-WALL REACTOR [E]
     Source: Lee, Keitz and Vogel, 1982
                               10-136
-------
          10.5.6.7  Supercritical Water, Advanced Electric and Vertical Tube
                    Reactors
     These incineration methods are basically in the developmental stage and
even though they seem to be very promising further testing is required before
these processes can be commercialized.  The supercritical water process
involves thermal destruction of organics in waste water based on the ability
of many organic compounds to dissolve in super critical water.  The process
can probably be applied to dilute organic wastewaters (5 to 10 percent by
weight) (Ross, 1984).

     The vertical tube reactor is a very unique system for the destruction of
organic wastes in a deep well with the appropriate temperature and pressure.
The advanced electric reactor is also a unique design to treat organic sub-
stances such as PCBs and others.  The process is based on a high temperature
fluidized bed reactor (Ross, 1984).
     10.5.7  Environmental Controls


          10.5.7.1  Air Pollution Controls


     Sources of air pollutants in hazardous waste incinerators include
products of incomplete combustion of organic constituents and conversion of
certain inorganic constituents resulting in gaseous or particulate
contaminants.

     Wet scrubbers are air pollution control devices that use a scrubbing
fluid to wash contaminants from a gas.  Both gaseous pollutants and
particulates may be removed, although particulates may be more
cost-effectively removed using other equipment in some cases (Peacy, 1984).

     Electrostatic precipitation is a process by which particles suspended in
a gas are electrically charged and separated from the gas stream on collecting
plates.  Both dry and wet electrostatic precipitators are available.  Dry
electrostatic precipitators have high efficiency for removal of particulates.
The wet electrostatic precipitator can theoretically remove organic fumes as
well as fine particulates (Peacy, 1984; Kiang and Metry, 1982).

     After burners are basically simple combustion chambers used to burn gases
being emitted from the incinerators.

     Fabric filters or baghouses are air pollution control devices, consisting
of a series of larger tubular bags which remove particulates from gases.
Baghouse filters can be 99 percent effective in the removal of particulates,
provided they are kept clean.

     Gaseous pollutants can be removed from flue gases using one of three
devices:  spray towers, packed-bed towers or plate towers.  All are mass

                                     10-137
-------
transfer devices for gas absorption.  Spray towers have lower removal
efficiencies than that of packed and plate towers and are seldom used for gas
removal (Kiang and Metry, 1982).


          10.5.7.2  Heat Recovery
     There are a variety of methods for recovering waste heat through various
types of heat exchangers.  The most commonly used device is the waste heat
boiler.  Each type of boiler has its own operating characteristics and can be
used to develop steam or hot water.

     Another device for energy recovery is the turbine generator.  It is more
costly than the heat exchangers but has more versatility in terms of product
usage (Peacey, 1984).
          10.5.7.3  Water Pollution Control


     When water scrubbers are used in an incineration system, the acid
scrubber water must be neutralized prior to discharge.


     10.5.8  Overall Operation and Design Considerations


     The overall design of a hazardous waste incinerator requires the
evaluation of many factors including:

     •  Transportation and unloading

     •  Waste segregation

     •  Toxicity, flammability and explosiveness of wastes

     •  Storage

     •  Monitoring
     •  Emissions control

     •  Residue handling and disposal
     •  Other environmental factors.


     10.5.9  Costs
     It is very difficult to calculate the cost of incineration because of the
high degree of complexity of the problem.  The basic factors involved are:

     •  The limited industrial experience with incineration of bulk quantities
        of wastes

                                     10-138
-------
     •  The differences  in  type  of  waste,  operation and design of an
        incinerator

     •  The difficulty in estimating  all  capital,  operating and maintenance
        costs.

The capital cost  is comprised  basically of the cost of purchased equipment and
installation.  The first is  a  firm  cost and the second can vary depending on
the geographic location, the assembly of  control devices, topography and the
availability of utilities.   It consists of the costs of labor and material for
foundations, structural  supports, handling and erection, electrical insula-
tion, construction, permitting and  test burn protocol, etc.  The purchased
equipment costs are comprised  of the  costs of auxiliary equipment, instru-
mentation and control devices  (Monsanto Research Corp., 1981).  Annual
operating and maintenance costs  consist of the cost of labor; material,
including fuel oil and chemicals; residual ash and  waste water disposal;
taxes; insurance; overhead;  etc.  These costs also  include depreciation over
the life of the facility and depend on  the depreciation method and interest
rate of the loan.  Estimated annual operation and maintenance costs vary
depending on size and characteristics of  the waste  stream, size and mechanical
complexity of the incinerator  and how it  is used.   Maintenance costs usually
run about 5% of the depreciable  capital cost.
          10.5.9.1  Examples of  Cost  Estimates
     Figure 10-55 depicts approximate  capital  costs  for  three basic types of
incinerators as a function of  thermal  input.   To obtain  the real cost of the
installed facility the numbers  from  the  figure should be multiplied by 1.5.
The costs of multiple hearth and  liquid  injection incinerators are similar for
the heat input ranging from 5  to  10  MBtu.   The rotary kiln is three times as
           FIGURE 10-55. GENERAL ESTIMATES OF COSTS FOR THREE
                       PREVALENT TYPES OF INCINERATORS
                      3.0

                      2.1
                    I-
                      0.6
                      0.2
                                    Rotary-kiln -a
                                          He»rtn-
?
                                         Liquid-injection
                            4  6  8 10    20   40  60 S0100
                                HIM Input, million Btu/h
                   Source: Vogel and Martin, 1983
                                     10-139
-------
expensive for the same heat input (Vogel and Martin, 1983).  The operating and
maintenance costs add several hundred thousand dollars to the capital costs
(Vogel and Martin, 1984).

     The estimation of capital costs of an exemplary rotary kiln incinerator
is given in Table 10-19.   The annual operation and maintenance cost for the
same incinerator are listed in Table 10-20.

     Estimated capital and O&M costs for a liquid injection incinerator are
shown in Table 10-21 and 10-22, respectively.  Table 10-23 shows another
estimate of O&M costs for a liquid injection incinerator based on the raw
material requirements shown in Table 10-24.  These costs were derived using a
cost estimation model (McCormick, 1983) and are considerably higher than costs
shown in Table 10-22.
                                      10-140
-------
            TABLE 10-19.  ESTIMATED CAPITAL COST FOR A ROTARY KILN
                 Item                                           1985 Cost $*


Combustion chambers:
  Refractory                                                   $  214,840
  Shell                                                           207,575
  Burners                                                          83,030

Water-storage system (two 10,000-gal tanks)                       122,470

Waste-feed system (screw feeder)                                   10,379

Ash-handling system                                                62,272

Energy-recovery boiler                                            200,984

Air-pollution control system (quench chamber,
  scrubber and absorber)                                          425,530

Blower, 304 stainless steel                                       126.620

Stack (carbon steel, 90 ft at $90/ft)                               8,406

Breeching (refractory-lined, 30 ft. at $300/ft)                     9,341

Total equipment cost                                           Si,571,447

Installation (50% of total equipment cost)                        786,254

Startup (10% of total equipment cost)                             157,238

Spare parts (8% of total equipment cost)                          125,790

Engineering (7% of total equipment cost)                          110,118

Instrumentation (20% of total equipment cost)                     314,580


Total capital cost                                             $3,065,467


 Adapted from Vogel and Martin, 1984.

*Costs updated from 1983 to 1985 dollars using ENR Construction Index.
                                     10-141
-------
       TABLE 10-20.  ESTIMATION OF ANNUAL OPERATION AND MAINTENANCE COST
                               FOR A ROTARY KILN
                 Item                                       1985 Cost $/yr*


Personnel (1 supervisor, 2 operators,
  4 yard-crew workers, 1 secretary)                         $  151,322

Electricity (473 hp) (7,200 h/yr)                              130,772

Water (3.1 x 108 gal/yr)                                       257,393

Auxiliary fuel
  Startup (10) (8 h) (10 x 10  Btu/h)                            4,670
  Operating (4.8 x 10  Btu/h)
  (7,200 h/yr)                                                 430,407

Chemicals (2.25 x 106 Ib lime/yr)                               39,128

Effluent disposal:
  Scrubber liquid (3.1 x 10  gal/yr)                           386,089
  Ash (2.88 x 10  Ib/yr)                                        14,945

Laboratory                                                      62,272

Maintenance (10% of total equipment cost)                      157,238

Refractory replacement (8-yr life)                              26,984

Direct operating cost                                        1,661,220

Value of recovered steam                                     1,245,450

Net operating cost                                             415,770
 Adapted from Vogel and Martin, 1984.

*Costs updated from 1983 to 1985 dollars using ENR Construction Index.
                                     10-142
-------
             TABLE  10-21.  CONCEPTUAL LEVEL CAPITAL COST ESTIMATES
                         FOR A LIQUID INJECTION SYSTEM
               Components                                      Cost

Site Acquisition and Development                            $  500,000
Tanks                                                          150,000
Pumps, Piping, and Compressors                                   35,000
REceiving Station and Compressor Enclosure                       70,000
Control Room, Auxiliaries, and Laboratory                      150,000
Liquid Injection Incinerator                                   175,000
Scrubbing System                                               175,000
Total Installed Cost:                                        1,255,000
  Construction, Overhead, and Fee                              125,000
  Contingency                                                  125,000
  Permitting                                                   100,000
  Start-up and Spare Parts Inventory                             25,000
Total Project Cost:                                         $1,630,000
        TABLE 10-22.  CONCEPTUAL LEVEL OPERATIONS AND MAINTENANCE COST
                    ESTIMATES FOR A LIQUID INJECTION SYSTEM
               Components                                      Cost

Labor and Supervision (2 shifts/day)                          $100,000
Fuel, Electric Power, Water and
  Chemicals and Caustic Soda)                                   75,000
Ash and Wastewater Disposal (assuming use of
  existing wastewater treatment plant)                           5,000
Waste Analysis                                                  30,000
Insurance, Taxes, and Overhead                                  50,000
Maintenance                                                     40,000
Depreciation                                                    75,000
Total Annual O&M Cost:                                        $375,000
 Maintenance costs are difficult to predict due to numerous and complex
 factors.  Conceptual level estimates for a liquid injection system are
 typically five percent of depreciable capital costs, or, as in this case,
 approximately $40,000/yr.
2
 Annualized capital costs depend on how the system is depreciated and the
 interest rate if a loan is taken out instead of taking from cash flow.
 Assuming a 10 year straight-line depreciation, annualized capital cost
 estimates are approximately $75,000/yr.  Given the current tax codes, such
 costs must take into account investment tax and energy recovery credits, as
 well as other corporate income tax adjustments.

Source:  Star, 1985
                                     10-143
-------
             TABLE 10-23.  ESTIMATED ANNUAL O&M COSTS AND CREDITS
                      FOR A LIQUID INJECTION INCINERATOR
                                                  1985
        Item                                   Annual Cost
Natural gas                                     $ 36,326
No. 2 fuel oil                                     1,245
Power                                             72,665
Water                                             12,450
Caustic soda solution (50 wt %)                  118,490
Liquid nitrogen                                    5,397
Sewer                                             60,197
Labor                                            166,060
Maintenance                                       77,841
Depreciation                                     155,681
Insurance/taxes                                   62,272
   Total                                        $768,624

Source:  McCormick, 1983.
Costs updated to $1985 using 1983 and 1985 ENR Construction Cost Indices,
                                     10-144
-------
           TABLE 10-24.  ESTIMATED RAW MATERIAL/UTILITY REQUIREMENTS
      Item
Normal Rate
Total Annual Quantity
Fuel
  Natural gas for flame
   stabilization
  No. 2 fuel oil for startup
1000 scfh
 100 gal/startup
    7 M ff
 1400 gal
Power
Id fan
Compressor
Blower
Pumps
Agitators
Total
Water
Caustic soda solution
(50 wt %)
Liquid nitrogen
Sewer use

95 hp
70 hp
35 hp
20 hp
nil
220 hp
110 gpm
230 Ib/hr

38 ft3/hr
110 gpm

-
-
-
-
-
1.15 Gwh
48 M gal
1.6 M Ib

270 M ft3
45 M gal

Source:  McCormick, 1983
                                     10-145
-------
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Allis Chalmers.  Undated.  Selection of Vibrating Screens.   General Screen
Information, Item 3.  Milwaukee, WI.

Azad, H.S. (ed.)  1976.  Industrial Wastewater Management Handbook.  McGraw-
Hill Book Company, NY.

Brunotts, V.A., L.R. Emerson, E.N.  Rebis, and A.J.  Roy.   1983.   Cost Effective
Treatment of Priority Pollutants Compounds with Granular Activated Carbon.
Management of Uncontrolled Hazardous Waste Sites.  Proceedings, Hazardous
Materials Control Research Institute, Silver Spring, MD.  pp. 209-216.

Calgon Carbon Corporation.  1983.  Interphase Groundwater Treatment System.
23-156a.  Pittsburgh, PA.

Calgon Corporation.  Undated.  Air  Purification with Granular Activated
Carbon.  Brochure 23-55.

Carter, L.W. and R.C. Knox.  1985.   Groundwater Pollution Control.  Lewis
Publishers Inc.  Chelsea, MI.  526  pp.

Chemical Separations Corp.  Undated.  Ion Exchange Systems.  Oak Ridge, TN.

Clark, D.E., P. Colombo, and R.M. Neilson, Jr.  1982.  Solidification of Oils
and Organic Liquids.  BNL-5162.  Prepared for:  Brookhaven National
Laboratory.  U.S. Department of Energy.  25 pp.

Conway, R.A. and R.D. Ross.  1980.   Handbook of Industrial Waste Disposal.
Van Nostrand Reinhold Co., NY.

Cullinane, M.J. and L.W. Jones.  1985.  Technical Handbook for
Stabilization/Solidification of Hazardous Waste.  Prepared for:  USEPA
Hazardous Waste Engineering Research Laboratory, Cincinnati, OH.

Gulp, R.L., Wesnar and G.L. Gulp.  1978.  Handbook of Advanced Wastewater
Pretreatment.  Van Nostrand Reinhold  Environmental Engineering Series, New
York, N.Y.

De Renzo, D. (ed.)  1978.  Unit Operation for Treatment of Hazardous Wastes.
Noyes Data Corporation, Park Ridge, NJ.

Derrick Manufacturing Corporation.   Undated.  Principles of High Speed
Screening and Screen Machine Design.  Buffalo, N.Y.  3 pp.

Dorr-Oliver, Incorporated.  1984.  The Dorrclone Hydrocyclone.  Bulletin DC-2.
Stamford.  CT.

Dorr-Oliver, Incorporated.  1983.  DSM Screens for the Process Industries.
Bulletin No. DSM-1.  Stamford.  CT.
                                     10-146
-------
                            REFERENCES (continued)
Dorr-Oliver.  1980.  Fine screening for mineral processing - Rappafine DSM
Screen.  Bulletin DSM6.  Stanford.  CT.

Dorr-Oliver, Incorporated.  1976.  Dorr-Oliver Clarifiers for Municipal and
Industrial Wastewater Treatment.  Bulletin No. 6192-1.  Stamford, CT.

Doyle, R.D.  1980.  Volume Reduction and Detoxification of Hazardous Wastes by
Encapsulation in an Asphalt Binder.  35th Industrial Waste Conference.  Purdue
University.  Anne Arbor Science Inc., Lafayette, IN.  pp. 761-767.

Eagle Iron Works.  1982.  Eagle Fine and Coarse Material Washers.  General
Catalog, Section C.  Des Moines.  IOWA.

Eagle Iron Works.  1981.  Eagle Water Scalping and Coarse Material Washers.
General Catalog, Section B.  Des Moines.  IOWA.

Erickson, P.R. and J. Hurst.  1983.  Mechanical Dewatering of Dredged
Slurries.  Ninth Meeting, U.S.-Japan Conference on Management of Bottom
Sediments Containing Toxic Substances.   Jacksonville, FL, October 17-18.

Ghassemi, M., K. Yu, and S. Quinlivan.   1981.  Feasibility of Commercialized
Water Treatment Techniques for Concentrated Waste Spills.  Prepared for:
USEPA, Municipal Research Laboratory, Cincinnati, OH.

Gooding, C.H.  1985.  Reverse Osmosis and Ultrafiltration.  Chemical
Engineering, January 5, 1985.  pp. 56-62.

Granlund, R.W. and J.F. Hayes.  Undated.  Solidification of Low-Level
Radioactive Liquid Waste Using a Cement-Silicate Process.  Delaware Custom
Material Inc., State College, PA.

Haliburton, T.A.  1978.  Guidelines for Dewatering/Densifying Confined Dredged
Material.  Technical Report DS-78-11.  Prepared for:  Office, Chief of
Engineers, U.S. Army, Washington, DC.

Hansen, S.P., R. Gumerman, and R. Gulp.  1979.  Estimating Water Treatment
Costs.  Volume 3:  Cost Curves Applicable to 2500 gpd to 1 mgd Treatment
Plants.  EPA-600/2-79-162c.  USEPA, Municipal Environmental Research
Laboratory, Cincinnati, OH.

Hoffman Muntner Corporation.  1978.  An Engineering/Economic Analysis of Coal
Preparation Plant Operation and Costs.   Preparation for US Department of
Energy and US Environmenatl Protection Agency.  Washington, D.C.  PB-285-251.

Jones, R.H., R.R. Williams and T.K. Moore.  1978.  Development and Application
of Design and Operation Procedures for Coagulation of Dredged Material Slurry
and Containment Area Effluent.  Prepared for:  Office, Chief of Engineers,
U.S. Army.  Technical Reprot D-78-54.
                                     10-147
-------
                            REFERENCES (continued)
Keitz, E.L. and C.C. Lee.   1983.   A profile of Existing Hazardous Waste
Incineration Facilities.   In Proceedings of the Ninth Annual  Research
Symposium Incineration and Treatment of Hazardous Wastes,  EPA 600/9-83-003.
US Environmental Protection Agency,  Industrial Environmental  Research
Laboratory, Cincinnati, OH.

Kiang, Y. and A.R. Metry.   1982.   Hazardous Waste Processing  Technology.   Ann
Arbor Science Publishers,  Inc., Ann Arbor,  MI.

Krebs Engineers.  Undated.  Krebs Cyclones  for the Mining  Industry.   Krebs
Bulletin No. 21-130.  Menlo Park, CA.

Krebs Engineers.  Undated.  Krebs Water Only Cyclones.  Menlo Park,  CA.

Krizek, R.J., J.A. Fitzpatrick and O.K. Atmatzidis.  1976.  Investigation of
Effluent Filtering Systems for Dredged Material Containment Facilities.
Prepared for:  Office, Chief of Engineers,  U.S. Army, Washington, DC.  Report
D-76-8.

Lee, C.C.  1983.  A comparison of innovative technology for thermal
destruction of hazardous waste.  In:  Proceedings of 1st Annual Hazardous
Materials Management Conference,  Philadelphia, PA.  July 12-14.

Lee, C.C., E.L. Keitz and G.A. Vogel.  1982.  Hazardous Waste Incineration:
Current/Future Profile.  In:  Proceedings of the National  Conference on
Management of Uncontrolled Hazardous Waste  Sites.  Nov. 29-Dec. 1, Washington,
D.C.

Lee, M.D. and C.H. Ward.  1984.  Reclamation of Contaminated  Aquifers:
Biological Techniques.  1984 Hazardous Material Spills Conferences
Proceedings, Government Institutes,  Inc., Rockville, MD.

Lubowitz, H.R. and C.C. Wiles.  1981.  Management of Hazardous Waste by
Clinque Encapsulation Process.  In:   Land Disposal of Hazardous Waste.
Proceedings of the Seventh Annual Research Symposium.  EPA-600/9-81-002b.
USEPA, Municipal Environmental Research Laboratory, Cincinnati, OH.
pp. 91-102.

Mallory, C. and M. Nawrocki.  1974.   Containment Area Facility Concepts for
Dredged Material Separation, Drying, and Rehandling.  Contract report D-74-6.
Hittraan Associates, Inc. Prepared for:  U.S. Army Engineer Waterways
Experiment Station.  Vicksburg, MS.

Metal Finishers' Foundation.  1977.   Treatment of Metal Finishing Waste by
Sulfide Precipitation.  PB-267-284.   Prepared for Industrial Environmental
Research Lab, Cincinnati, OH.

Metcalf and Eddy, Inc.  1979.  Wastewater Engineering Treatment Disposal.
McGraw-Hill, Inc., N.Y.

                                     10-148
-------
                            REFERENCES (continued)
Monsanto Research Corporation.  1981.  Engineering Handbook In Hazardous Waste
Incineration.  NTIS-PB81-248163.

Moore, Gardner and Associates.  1983.  Final Activity Report Shipyards
Investigation Pearl Harbor Navy Shipyard, Pearl Harbor, Hawaii.  Prepared for
Department of the Navy, Naval Facilities Engineering Command.

Nalco Chemical Co.  1979.  Nalco Water Handbook.  McGraw-Hill, Company,
New York, NY.  p. 12-1.

O'Brien, R.P. and J.L. Fisher.  Undated.  There is an Answer to Groundwater
Contamination.  Reprinted from:  Water/Engineering and Management.

O'Brien, R.P. and M.H. Stenzel.  1984.  Combining Granular Activated Carbon
and Air Stripping.  Reprinted from Public Works, December 1984.

Oklahoma State University.  1973.   Feasibility Study of Hydrocyclone Systems
For Dredge Operations.  AD-766-212, Prepared for:  Army Engineer Waterways
Experiment Station.

Parkson Corporation.  1984.   Lamella Gravity Settler/Thickener.  Bulletin
LT-103.  Fort Lauderdale, FL.

Peacy, J.  1984.  A Special  Roundup Feature Report on Incineration.  Pollution
Engineering.  Vol. 16, No. 16.  April 1984.

Perry, R.H. and C.H. Chilton.  1973.  Chemical Engineers Handbook.  McGraw
Hill Book Company, New York, NY.

Pradt, L.A.  1976 (updated 1972).   Developments in Wet Air Oxidation.
Reprinted from:  Chemical Engineering Progress.  Vol. 68, No. 12.
pp. 72-77.

Rockwell International.  1980.  Molten Salt Destruction of Hazardous Wastes.
Pub. 523-L-18-1.  Canoga Park, CA.

Ross, R.D.  1984.  Hazardous Waste Incineration:  More Attractive Now Than
Ever Before.  Hazardous Materials and Waste Management.  Vol. 2, No. 5.

Shuckrow, A.J., A.P. Pajak,  and C.J. Touhill.  1980.  Management of Hazardous
Waste Leachate.  SW-871.  Prepared for:  USEPA, Municipal Environmental
Research Laboratory, Cincinnati, OH.

Smith, C.L. and K.E. Zenobia.  1982.  Pozzolanic Microencapsulation for
Environmental Quality Assurance.  In:  37th Industrial Waste Conference.
Purdue University.  Ann Arbor Science, MI.  pp. 397-403.
                                     10-149
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                            REFERENCES (continued)
Solsberg, L.B., R.D.  Parent,  and S.L.  Ross,  1985.   A Survey of Chemical  Spill
Countermeasures.  Prepared for Environmental Emergencies Technical Division,
Environmental Protection Service, Ottawa,  Canida.   January, 1985.

Spencer, R.W., R.H.  Reifsnyder, and J.C.  Falcone.   1982.   Applications of
Soluble Silicates and Derivative Materials.   Management of Uncontrolled
Hazardous Waste Sites Proceedings, Hazardous Materials Control Research
Institute, Silver Spring, MD.  pp. 237-243.

Star, A.M.  1985.  Cost estimating for hazardous waste incineration.
Pollution Engineering.  Vol.  17, No. 4.

State of California,  Governors' Office of Appropriate Technology.   1981.
Alterantives to the Land Disposal of Hazardous Wastes.  An Assessment for
California.

United States Gypsum Company.  1982.  Environstone Gypsum Cement:   A Major
Breakthrough in Radwaste Binder Technology.   TAC-225/USG/6-82.  Chicago,  IL.

USEPA.  1973.  Process Design Manual for Activated Carbon Adsorption.  EPA
625/l-71-002a.

USEPA.  1978.  Sludge Handling and Conditioning.  EPA 430/9-78-002.
Washington, DC.

USEPA.  1979.  Process Design Manual:   Sludge Treatment and Disposal.  EPA
625/1-79-011.  Municipal Environmental Research Laboratory, Cincinnati,  OH.

USEPA.  1980.  Innovative and Alternative Technology Assessment Manual.   EPA
430/9-78-009.  Office of Water Program Operations, Washington, DC and
Municipal Environmental Research Laboratory, Cincinnati, OH.

USEPA.  1982a.  Design Manual:  Dewatering Municipal Wastewater Sludges.
EPA-625/1-82-014.  Municipal Environmental Research Laboratory, Cincinnati,
OH.

USEPA.  1982b.  Guide to Disposal of Chemically Stabilized and Solidified
Waste.  SW-872.  Office of Solid Waste and Emergency Response, Washington, DC.

Van Note, R.H. et al.  1975.   A Guide to the Selection of Cost-Effective
Wastewater Treatment Systems.  EPA-430/9-75-002.  USEPA, Washington, DC.

Vatavuk, W.M.  and R.B. Neveril.  1983.  Cost of Flares.  Chemical Engineering,
Vol. 90, No. 4.

Vogel, G.A. and E.J.  Martin.    1984.  Example of Incineration Cost Estimation.
Chemical Engineering.  Vol. 91, No. 3.
                                     10-150
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                            REFERENCES (Continued)
Vogel, G.A., E.J. Martin.  1983.  Equipment Sizes and Integrated Facility
Costs.  Chemical Engineering Vol. 90, No. 18.

Water Purification Associates.  1975.  Innovative Technologies for Water
Pollution Abatement.  NTIS PB-247-390.

Weber, W.J.  1972.  Physiochemical Processes for Water Quality Control.
Wiley-Interscience, New York, NY.

Whittaker, H.  1984.  Development of a Mobile  Reverse Osmosis Unit for Spill
Clean Up.  Hazardous Material Spills Conference, April 9-12.  Government
Institutes, Inc., Rockville, MD.

Whittaker, H., C.I. Adams, S.A. Salo, and A. Morgan.  1985.   Reverse Osmosis
at the Gloucester Landfill.  In:  Proceedings  of the Technical Seminar on
Chemical Spills, Environment Canada, Ottawa, Canada,  pp.  191-207.
                                     10-151
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                                  SECTION  11

             CONTAMINATED WATER SUPPLIES AND WATER AND SEWER LINES
     Hazardous substances can enter public water  systems  through  a wide
variety of pathways, contaminating the components of  the  systems  as well  as
the water.  Once contaminated, water systems can  serve  as  secondary sources  of
contamination, and the systems' users can be exposed  to hazardous substances
over long periods of time.

     Sanitary and storm sewers can become contaminated  by infiltration of
leachate or contaminated groundwater through cracks,  ruptures,  or poorly
sealed joints in piping and by direct discharges  into the lines.  Potable
water supply mains can become contaminated by contact with contaminated water
that may inadvertantly flow through them, or by infiltration  of leachate  or
contaminated groundwater.  However, water mains are less  susceptible  to the
infiltration of contaminants, since they are generally  full-flowing,  pres-
surized systems.  The public health consequences of the contamination of
municipal mains carrying potable water supplies to commercial  and residential
consumers are potentially much greater than the consequences  of the contami-
nated sewage flowing to a treatment plant or of surface runoff  draining to
surface waters.

     This Section presents methods for providing water  supplies of acceptable
quality with the minimum disruption of service; the methods are as follows:

     •  Water supply replacement:
        -  New central water supply
           Point-of-use water supplies
     •  Water Treatment:

           Central water treatment
           Point-of-use water treatment

     •  Alteration of water and sewer pipelines:
           Replacement

           Inspection and leak detection
        -  Cleaning

           Repairing and lining.
                                      11-1
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11.1  Replacement of Contaminated Central Water Supplies


     Replacement of central water supplies, or sources of water  that  serve
many users through central distribution systems, generally  involves one  or
more of the following approaches:

     •  Purchase of water from another supply
     •  Provision of a new surface water intake(s)

     •  Provision of a new groundwater well(s).

     The contaminated water supply may be abandoned or may  be blended with  the
new supply to achieve acceptable water quality by dilution.  Combinations of
the approaches may be employed either concurrently (multiple replacement
supplies) or consecutively (emergency water purchased  from  a neighboring
supply unit, followed by new wells or intakes.)

     Purchase of treated water from another supply requires a cross-
connection^) between the systems.  Many neighboring public water  departments,
authorities, and companies maintain networks of interconnections that allow
ready flow and meeting between systems for emergencies such as  droughts,
fires, line breakage, or malfunction of treatment  facilities.   Where  cross-
connections do not exist, water  transmission  lines can be  installed.   The
information provided in Section  11.5 generally applies to new water pipelines.
Numerous references are available that guide  the design  and installation of
water transmission and distribution systems,  including Fair (1971) and
American Society of Civil Engineers (ASCE, 1975).

     Provision of new surface water intake may be  feasible  where a groundwater
source is to be replaced or where a replacement surface  water  intake  would
hydraulically isolate the water  supply system  from contaminated  surface  water
(e.g., intake upstream of the source of contamination).

     Surface water is drawn from rivers, lakes, and reservoirs  through
relatively simple submerged intake pipes, or  through fairly elaborate
towerlike structures that rise above the water surface.   Important in the
design and operation of intakes  is that the water  they draw be  as  clean,
palatable, and safe as the source of supply can provide.  River intakes  are
constructed well upstream from points of discharge of  sewage  and industrial
wastes.  Optional location should take advantage of deep water,  a  stable
bottom and favorable water quality, all with  proper reference  to protection
against  floods, debris, ice, and river traffic.  Small streams  may be dammed
up  by diversion or intake dams to keep intake  pipes submerged  and  preclude
hydraulically wasteful air entrainment.  Lake  intakes  are  sited with  due
reference to sources of pollution, prevailing  winds, surface  and subsurface
currents, and shipping lanes.  Shifting the depth of draft  makes it possible
to  collect clean bottom water when the wind is offshore,  and,  conversely,
clean surface water when the wind is onshore.  Reservoir intakes, resemble  lake
intakes  but generally lie closer to shore  in  the deepest part  of the
reservoir.  They are often incorporated into  the impounding structure itself
(Fair, 1971).

                                     11-2
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     The feasibility of providing new  surface water  intakes  is  dependent  on
numerous case-specific requirements  and conditions,  summarized  as  follows:

     •  Proximity of the point of intake  to  the water  supply system

     •  Peak demand flow versus historic  and predicted  low  flow in the  water
        body

     •  Downstream environmental, recreational, and  commercial  effects  of
        reduced flow

     •  Quality of the surface water and  corresponding  treatment requirements.

     Provision of new groundwater wells is often  feasible where  the  extent of
aquifer contamination is relatively  confined and  would  not  be expected  to be
drawn to the area of influence of the  new wells,  or  where other  (usually
deeper) aquifers can be tapped as a  replacement water  supply.   The information
provided in Section 5.1 generally applies to the  design  and  construction  of
new groundwater wells.


11.2  Point-of-Use Water Supplies


     Central water supplies that are contaminated  at the source  or in trans-
mission through pipelines can be replaced permanently  or temporarily with an
independent supply at each point of  usage.   Such  supplies could  include one or
a combination of the following:

     •  Bottled and bulk water

     •  Point-of-use wells
     •  Collection of rain water.

     The use of bottled and bulk water is common  for temporary  or  semi-
temporary water supplies on an emergency  basis until more permanent  water
supply arrangements can be made.  Bottled water is widely available  in  small
quantities from common retail outlets  (grocery and drug  stores)  and  in  large
quantities from commercial distributors.  Larger  bottles (e.g.,  five-gallon
"water cooler" bottles) require dispensers in order  to  be conveniently  used.
Their full weight (approximately 50  pounds) may present  handling and
change-over problems for some users.

     Bulk water can be provided in portable  tanks  (trailers  or  tank  trucks) by
commercial, clean water contractors  and by public  emergency  service  organiza-
tions (e.g., Army National Guard).   Tanks normally used  for  other  purposes,
such as milk tank trucks, have also  been  used.  The  tanks are typically made
available to homeowners at temporary,  centrally located  distribution points,
where small containers can be filled for  home use.   Whole tanks  can  be  made
available to commercial and institutional establishments.
                                     11-3
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     Point-of-use wells, or individual wells for each user establishment, may
be feasible as a permanent alternative to a contaminated central supply,
provided that the available groundwater is and can be expected  to remain
non-contaminated.  The information provided in Section 5.1 generally applies
to development of new groundwater wells.

     Rainwater is rarely the immediate source of municipal water supplies, but
could serve as a replacement to a contaminated water supply.  The use of rain-
water is generally confined to farms and towns in semiarid regions devoid of
satisfactory groundwater or surface water supplies.  For individual users,
rainwater running off the roof is led through gutters and downspouts to a
cistern situated on or below the ground.  Cistern storage converts the
intermittent rainfall into a continuous supply.  For municipal  service, roof
water may be combined with water collected from sheds or catches on the
surface of ground that is naturally impervious or rendered so by grouting,
cementing, paving, or similar means (Fair, 1971).

     The gross yield of rainwater supplies is proportional to the receiving or
drainage area and the amount of precipitation.  Because of the  relatively
small catchment area available, roof drainage cannot be expected to yield an
abundant supply of water, and a close analysis of storm rainfalls and seasonal
variations in precipitation must be made if catchment areas, standby tanks,
filters, and cisterns are to be proportioned and developed properly (Fair,
1971).
11.3  Treatment of Contaminated Central Water Supplies


     Central water supplies that are contaminated at  the  source  can be  treated
to acceptable quality at central treatment  systems.   For  some  supplies,  such
as in small communities that pump groundwater directly to distribution  systems
without treatment, central treatment may require installation  of new  facili-
ties.  For other supplies, such as in  large communities that already  treat
surface water before distribution, upgrading of existing  treatment with the
installation of polishing units may be necessary (Morrison,  1981).

     Available water treatment methods include physical,  chemical, and
biological technologies, and combinations of these methods may be used  for
removal of some contaminants.

     Many of the technologies described in  Section  10-1,  for treatment  of
aqueous wastes also apply to treatment of contaminated water supplies.   In
general, however, those technologies that are normally associated with
"polishing" (i.e., removal of low concentrations of contaminants), such as
activated carbon, ion exchange, and reverse osmosis,  are  most  applicable to
treatment for public water supplies.
                                      11-4
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11.4  Point-of-Use Water Treatment


     11.4.1  General Description


     Central water supplies that are contaminated at  the  source  or  in
transmission can be treated to acceptable quality at  the  point of use  (POU)
with a variety of commercially available systems.  Most applications of  POU
treatment units are for aesthetic purposes (taste, odor,  and color), although
their use is increasing for removal of organic contaminants from drinking
water (Anderson, 1984a).

     POU units are generally used in one of the  following  situations in
residential applications:

     •  Line-bypass, where separate faucets are  provided  for treated and
        non-treated water; treated water is generally used for drinking,
        cooking, etc.

     •  Faucet-mounted, where all water passing  through the faucet  is  treated.

     •  Whole-house, where all water entering the house is treated.

Line-bypass systems afford a compromise, providing only for treatment  of water
to be consumed, thereby minimizing treatment demands  and  costs.

     POU treatment processes include the following (Anderson, 1984a; Perry,
1981):

     •  Activated carbon

     •  Activated alumina

     •  Reverse osmosis

     •  Ion exchange

     •  Distillation

     •  Ozonation
     •  Ultraviolet irradiation.

Of these processes, activated carbon is the most widely used and accepted
process.  Reverse osmosis and ion exchange are also widely available for
applications where more stringent water quality  requirements apply  (hospitals,
laboratories, etc.).  Section 10.1 should be consulted for the applications
and limitations of these methods.
                                     11-5
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     11.4.2  Applications/Limitations
     POU units are designed to remove a wide variety of contaminants from
water.  Manufacturers' claims vary, and numerous studies have been conducted
to test the effectiveness of various units (Anderson, 1984a and b; Perry,
1981; Taylor, 1978).

     Table 11-1 summarizes the general applications and limitations of the
commonly used types of POU units.  A major limitation common to all POU units
is their reliance on the user (or service contracted by the user). If the
units are not properly installed, operated, and maintained, the desired treat-
ment may not be affected, or the accumulated contaminants may be  released from
the treatment unit after the treatment material is exhausted.  (Taylor, 1978).
                                  TABLE 11-1.
  APPLICATIONS AND LIMITATIONS OF COMMONLY USED POINT-OF-USE TREATMENT UNITS
       Process
   Applications
         Limitations
Activated carbon
Organics, hydro-
carbons, chlorine,
trihalomethanes (THM)
some pesticides
Reverse osmosis
Fluoride, total dis-  <
solved solids, sodium,
sulfate, salts, metals
 Ion  exchange
Dissolved minerals,
metals, most inorganics
Potential for excess growth of
bacteria (Taylor, 1978)

Short-lived effectiveness for
some contaminants (chlorine,
THM, pesticides) (Taylor, 1978)

Potential desorption (release
of contaminants) following
exhaustion of carbon (Taylor,
1978)

High-pressure required to
affect filtration

Low flow rate capacity requires
storage tank and/or multiple
systems in parallel
                                      11-6
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     11.4.3  Design Considerations


     The primary design considerations for POU units are 1) selection of  the
appropriate units for the contaminant(s) of concern, 2) selection of the
appropriate hydraulic capacity for the application, and 3) provision of
appropriate criteria and schedules for maintaining  the units.  This informa-
tion is generally available from the manufacturer or supplier.

     Manufacturers' and suppliers' performance information should be confirmed
by laboratory or trial tests under any of the following circumstances:

     •  Information has not been confirmed by a reputable organization or
        laboratory (National Sanitation Foundation  (NSF), 1981)

     •  Disparate contaminants are present

     •  Concentrations of contaminants vary widely  over time

     t  Contaminants and concentrations pose a high risk to human health

     •  Large numbers of units are to be employed.


     11.4.4  Construction/Implementation Considerations


     Installation procedures are provided by the manufacturer of each POU
unit.  Installation should be made by a licensed plumber and/or approval of
the installation should be given by a local plumbing inspector.  This is
particularly important for whole-house units and by-pass units to ensure  that
backflow and inappropriate cross-connections are averted.


     11.4.5  Operation, Maintenance, and Monitoring


     Once installed, POU units operate relatively passively and require little
or no attention.  Proper maintenance and monitoring, however, are essential to
the effectiveness and safety of the units.  Maintenance generally consists of
changing the cartridges on a regular schedule.  However, few units give any
detectable indication of having reached capacity.  Conservative change-over
schedules are recommended to help ensure that the units continuously serve
their intended purpose.  Alternatively, frequent monitoring of the quality of
the treated water could be conducted by sampling and analysis to identify the
need for cartridge changes. Many full-service water treatment companies
provide installation and maintenance services.
                                     11-7
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     11.4.6  Technology Selection/Evaluation
     The selection of the appropriate POU unit is based  largely on  the
contaminants to be removed.  The applicability of the commonly used type of
POU units is provided in Table 11-1.  Reliability of performance  should be a
major consideration in evaluating POU units relative to  other water supply or
treatment technologies, as their reliance on the user or user-contracted
services for installation and maintenance does not necessarily ensure a
continuously safe water supply.
     11.4.7  Costs
     Typical initial equipment, installation, and monthly maintenance  costs
for POU treatment devices are shown in Table  11-2.  Maintenance  costs  include
changing of treatment cartridges on schedules consistent with  the units'
capacities and residential rates of water consumption.
             1985
               TABLE 11-2.
COSTS FOR POINT-OF-USE WATER TREATMENT SYSTEMS
        Type of System
          Initial Costs
Maintenance Cost
Activated carbon

Activated alumina

Reverse osmosis

Deionization

Combined activated carbon
          $300-400/unit

          $200-400/unit

          $550/unit

          $700/unit

          $700-800/unit
   $2-3/month

   $1-4/month

   $7-11/month

   $4-6/month

   $8-12/month
Source:  Anderson,  1984b; Consumers Union  1984;  Ingram,  R.,  Culligan  Water
Conditioning of Greater Washington, Vienna,  VA,  personal communication,  March
1985.
                                      11-8
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11.5  Replacement of Water and Sewer Lines


     11.5.1  General Description


     Replacement of water and sewer pipelines that are contaminated by contact
with hazardous substances is seldom more cost-effective than rehabilitation,
but may often be the only practical alternative.  Replacement  involves exca-
vation of trenches, laying of new lines with noncontaminated pipe materials,
laying new connections and/or tying in connections, and associated backfilling
and surface restoration.  Contaminated pipelines may either be abandoned
in-place or removed in the course of trench excavation.  Construction of water
and sewer lines is common in land development projects and the associated
methods, materials, and equipment are well-established.


     11.5.2  Applications/Limitations


     Pipeline replacement is applicable to virtually all cases of pipeline
contamination.  Excavation and replacement of defective sewer pipe segments is
normally undertaken when the structural integrity of the pipe has deteriorated
severely; for example, when pieces of pipe are missing, pipe is crushed or
collapsed, or the pipe has large cracks—especially longitudinal cracks, and
alternative rehabilitative techniques are not feasible.  In addition, pipeline
replacement is often required when the pipe is significantly misaligned (Water
Pollution Control Federation (WPCF), 1983).  Factors that would limit the
feasibility of pipeline replacement are:

     •  Disruption of service and interim provisions
     •  Accessibility of pipeline and connections
     •  Interference of other utilities
     •  Disruption of vehicular traffic
     •  Depth of excavation
     •  Soil and groundwater
     •  Costs.

     The primary disadvantage of pipeline replacement is the high cost.
Analyses to determine the cost-effectiveness of pipe replacement must include
all costs associated with the replacement.  These costs typically include
pavement removal and replacement; excavation; possible substitution of select
backfill to replace poor quality existing material; dewatering and shoring,
pipe materials and couplings, and traffic control.  Potential cost increases
resulting from interference with other underground utilities and narrow
casements or limited space for construction must also be considered.  In
addition, consideration must be given to the need for temporary flow rerouting
                                     11-9
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to maintain service.  Depending on the service  life assumed  for other  reha-
bilitation methods, the possible higher capital costs may be somewhat  offset
by the longer service life a new line provides  (WPCF, 1983).


     11.5.3  Design Considerations


     In general, new pipeline systems will mimic the systems that  they replace
(size, material, grade, location, capacity, etc.).  The considerations  that
govern the design of new systems will apply, but not control.  Logistics  and
the presence of fixed constraints will dictate  how  the replacement  system is
designed.  However, the need for replacement may provide an  "opportunity" to
upgrade the systems in terms of capacity, improved materials and methods,
location, and/or direction of flow, and some consideration would be given to
criteria for the design of new systems (WPCF, 1983).

     The design of water distribution and sanitary  sewer systems is addressed
in numerous manuals and guidebooks, including ASCE  (1975 and 1976).   Informa-
tion that is needed as input to the design includes:

     •  Population drawing from or contributing to  the system

     •  Per capita water demand or sewage discharge

     •  Commercial, industrial, and institutional demand or  discharge

     •  Minimum and peak daily demand or discharge

     •  Fire-fighting requirements

     •  Soil, groundwater, near-surface and geologic conditions

     •  Topography and grades

     •  Locations of potentially interfering features (utilities,  buildings,
        etc.) .

     ASCE (1976) recommends  that estimates of sewage flow be based on  con-
sideration of the  following:

     •  The design period during which the predicted maximum flow  will not be
        exceeded,,  usually 25 to 50 years in the future.

     •  Domestic sewage contributions based on  future population and future
        per-capita water consumption.  If a more  satisfactory  parameter than
        water consumption is available,  that parameter should  be used.

     •  In some  instances, maximum  flow  rates may  be determined  almost
        entirely by extraneous  flows,  the  source  of which may  be  foundation,
        basement,  roof, or areaway  drains,  storm  runoff  entering  through
        manhole covers, or infiltration.

                                      11-10
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     •  Commercial area contributions are sometimes assumed to be adequately
        provided for in the peak allowance for per capita sewage flows in
        small communities

     •  Industrial waste flows should include the estimated employee contri-
        bution, estimated or gauged allowances per acre for industry as a
        whole, and estimated or actual flow rates from plants with process
        wastes that may be permitted to enter the sanitary sewer

     •  Institutional wastes are usually domestic in nature although some
        industrial wastes may be generated by manufacturing at prisons,
        schools, hospitals, etc.

     •  Air-conditioning and industrial cooling waters, if permitted to enter
        sewers, may amount to 1.5 to 2.0 gpm per ton of nonwater-conserving
        cooling units

     •  Infiltration may occur through defective pipe, pipe joints, and
        structures.  Design allowances should be larger (under some circum-
        stances, very much larger) than those stipulated in construction
        specifications for which acceptance tests are made very soon after
        construction.

     The relative emphasis given to each of the foregoing factors varies among
engineers.  Some have set up single values of peak design flow rates for the
various contributory items listed above.  It is recommended, however, that
maximum and minimum peak flows used for design purposes be developed step by
step, giving appropriate consideration to each factor which may influence
design.  (ASCE, 1976).

     If a sewer is to transport stormwater or wastewater from one location to
another, it must be constructed sufficiently deep (below the ground surface)
to receive these flows from basic or service connections.  It should be
resistant to both corrosion and erosion and its structural strength must be
sufficient to carry backfill, impact, and live loads satisfactorily.  The size
and slope, or gradient, of a sewer must be adequate for the flow to be carried
and be sufficient to avoid deposition of solids.  The type of  sewer joint
must be selected to meet the conditions of use as well as those of the ground.
Economy of maintenance, safety to personnel and the public, and public
convenience during its life and during construction also must be considered
(ASCE, 1976).

     The pipe material used for sanitary and storm sewers can influence other
design decisions and should, therefore, be selected early in the design
process.

     Factors that should be considered in the selection of materials for both
water and sewer construction are (ASCE, 1976):

     •  Flow characteristics-friction coefficient

     •  Life expectancy and use experience

                                     11-11
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     •  Resistance to scour
     •  Resistance to acids, alkalis, gases, solvents, etc. (sewers only)
     •  Ease of handling and installation
     •  Physical strength
     •  Type of joint - watertightness and eas-e of assembly
     •  Availability and ease of installation of fittings and connections
     •  Availability in sizes required
     •  Cost of materials,  handling, and installation.

     No single material will meet all conditions that may be encountered in
sewer design.  Selections should be made for the particular application and
different materials may be selected for parts of a single project (ASCE,
1976).
     New materials are continuously being offered for use in sewer construc-
tion.  Some of the more commonly used materials are (ASCE, 1976):
     •  Asbestos cement
     •  Brick masonry
     •  Vitrified clay
     •  Concrete
        -  Precast
           Reinforced precast
           Cast-in-place
     •  Iron
        -  Cast iron
           Ductile iron
     •  Fabricated steel
           Corrugated
           Plain
     •  Organic synthetic materials
           Solid-wall plastic (polyvinyl chloride (PVC), polyethylene,
           acrylonitrile-butadiene-styrene (ABS), fiberglass reinforced
           plastic)
           Truss pipe
           Corrugated polyethylene.
                                     11-12
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     Estimates of flow and system pressure in water distribution systems are
based on the following (Fair, 1971):

     •  Domestic, industrial, and other normal uses, determined in a manner
        similar to estimating sewage flow

     •  Standby requirements for fire-fighting as required by local codes
        and/or the American Insurance Association

     •  Estimates of system leaking

     •  Calculation of in-transit frictional pressure losses.

     A variety of pipe materials are also available for water systems; among
the most common are (ASCE, 1975):

     •  Iron

           Ductile iron

        -  Cast iron

     •  Concrete

     •  Asbestos - cement

     •  Steel

     •  Organic synthetic materials:

        -  Polyvinyl chloride (PVC)

        -  Polyethylene (PE)

           Acrylonitrile - butadiene - styrene (ABS).


     11.5.4  Construction/Implementation Considerations


     A variety of conventional and nonconventional methods are available for
constructing water and sewer lines.  The most common method is open-trench
excavation, which often requires lateral bracing of trench walls in deep cuts
and/or non-cohesive soils.  This method of sewer construction is described in
ASCE, (1976).  Other methods of construction include:

     •  Augering, or boring, where the pipe is pushed through the soil and the
        soil ahead of the pipe is removed by an auger that is advanced with
        the pipe

     •  Jacking, where the pipe is pushed through the soil and the soil ahead
        of the pipe is removed by laborers working from inside the pipe

     •  Tunneling by various means.
                                     11-13
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     11.5.5  Operation, Maintenance, and Monitoring


     Replacement water and sewer lines require no operations, maintenance,  or
monitoring beyond that required for other newly constructed lines.  For water
lines, this includes flushing, leak detection and repair, and hydrant  testing
to ensure that fire-fighting requirements are met (Fair, 1971).  For sewer
lines, this includes occasional flushing and cleaning  (see Section  11.6),
removal of blockages, ensuring adequate ventilation, and leak detection and
repair.


     11.5.6  Technology Selection/Evaluation


     Factors that generally favor the selection of  line replacement over  other
technologies are the complete removal of contaminants  from the  system  and the
provision of new systems with associated functional  lines.  Major drawbacks of
replacement are disruption of surface activities and costs.  Performance  and
reliability of replacement systems are the maximum  obtainable;  i.e., new
systems are the basis of comparison for evaluating  other pipeline alteration
technologies.


      11.5.7  Costs
     Typical costs  for  replacement  of water  and  sewer  lines  ae  provided  in
Table  11-3.
 11.6   Inspection  and Cleaning of Water  and  Sewer Lines


      11.6.1  General Description


      Available  techniques  for inspecting  and  cleaning  sewer  lines  are
 generally applicable to water lines.  However,  the water  lines  are normally
 smaller  in diameter than sewer  lines, and size  is often a limiting factor in
 the applicability of inspection and  cleaning  technologies.   Inspection
 techniques include smoke testing, dye-water flooding,  first-hand visual
 observation, and  closed-circuit television  visual observation.

      Inspection is generally conducted  to identify one or more  of  the
 following conditions:

      •  Points  of groundwater leakage
      •  Structural defects  in need of repair
                                      11-14
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                                  TABLE  11-3.
              1985 COSTS FOR REPLACEMENT OF WATER AND  SEWER  LINES
     Item
Unit
Cost Per Unit
Sewer pipe, material and
installation, in-place:
     8-inch diameter
     18-inch diameter
     36-inch diameter

Water pipe, material and
installation, in-place:
     2-inch diameter
     4-inch diameter
     12-inch diameter

Pipe bedding material

Trench excavation,
backfill, and
compaction:

     Water lines
     Sewer lines
Linear foot
Linear foot
Cubic yard
Linear foot
Cubic yard
                    $6-10
                    $13-31
                    $33-120
$3-7
$5-11
$16-27

$14-25
$1-3
$6-10
     Source:  Godfrey, 1984


     •  Points of connection

     •  Areas in need of cleaning.

     Inspection of pipelines for  leaks or infiltration points may be  part  of  a
regular sewer or water line maintenance program.  Methods to detect and  locate
pipeline breaches include the use of dyes and other tracer chemicals, patented
audiophone leak detectors, smoke  testing, and installation of pressure gages
along a given length of pipe to monitor changes in hydraulic gradient (Linsley
and Franzini, 1979).  The interiors of small diameter sewers and large
diameter water lines are commonly inspected by pulling skid-mounted minia-
turized closed-circuit television cameras through the line.  The entire
inspection can be recorded on videotape for future reference.
                                     11-15
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     Cleaning of water and sewer line removes deposits  and debris  from  the
pipelines and is conducted for one or more of the  following reasons:

     •  Improve flow conditions and capacity

     •  Allow visual inspections
     •  Provide clean surfaces for placement of repair  materials.

     Available sewer-cleaning techniques include mechanical scouring, hydrau-
lic scouring and flushing, bucket dredging, suction cleaning with  pumps or
vacuum, chemical absorption, or a combination of these  methods.  Access to
sewer lines for interior cleaning and repair is most commonly afforded  by
manholes.  Basin inlets and service connections provide additional points of
access.  Service and fire hydrant connections allow access to municipal water
lines.
     11.6.2  Applications/Limitations


     Pipeline inspection  is applicable to  all visually  observable  cases  of
pipeline contamination or leakage of contaminated water.  The methods  are
well-developed and accepted.  Small-diameter pipelines  (less than  6  inches)
cannot be inspected by closed-circuit television, and pipelines  less than  48
inches in diameter cannot readily be inspected  first-hand by workmen.
Television inspection offers the advantages of worker safety and a permanent
videotape record of the inspection.  It  is common practice  to clean  pipelines
before inspection to ensure visibility of  defects and free  access  of workmen
and/or equipment.


     11.6.3  Design Considerations


     Design of inspection and cleaning operations for water and  sewer  lines
consists primarily of planning  for  the logistics of  implementation.  Sections
of pipeline to be inspected and/or  cleaned are  selected based on evidence  of
the presence of contamination or contaminated seepage;  sections may  be added
or deleted in process, depending on interim findings.   Critical  points of
operation such as access manholes,  base  of operation, and material storage are
selected.  Methods of managing  disruption  of service (water or sewer)  and
surface activities such as traffic  are also planned.  Affected parties are
notified in advance of the planned  work.


     11.6.4  Construction/Implementation Considerations


     Smoke bombs or canisters are used to  generate  the  smoke required  for
smoke testing of pipelines.  The smoke should be nontoxic,  odorless, and non-
staining.  Air blowers are used to  force the smoke  into the pipes.  Smoke
                                      11-16
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coming out of the ground, catch basins, pipes, and other sources during  the
test is noted and recorded by observers and photographs are  taken  for  perman-
ent documentation of the results. Sand bags and/or plugs can be used to  block
the sewer sections to prevent the smoke from escaping  through  the  manholes and
adjacent sewer pipes (WPCF, 1983).

     Dye-water flooding is used to simulate rainfall and thus  identify points
of runoff-related infiltration and sources.  Equipment needed  for  dye-water
testing is limited to that required to carry the water to  the  testing  site and
to block the sewer sections to be tested.  A fire hose is  all  that is  needed
to deliver the water to the testing site.  When the water  source is not  close
by, water tankers are required to deliver the water.   Sand bags or sewer pipe
plugs are normally used to block the sewer sections.  Fluorescent  dyes are
usually employed for high visibility (WPCF, 1983).

     The following is a general procedure for dye testing  for  possible
infiltration from a storm sewer to a sanitary sewer; similar procedures  are
used for evaluating other sources:

     •  Plug both ends of the storm drain section to be tested with sand bags
        or other materials.  Block all the overflow and bypass points  in the
        sewer section.  Provide bypassing of flow, if necessary.

     •  Fill the storm drain section with water from fire hydrants or  other
        nearby water sources.  Add dye to the water.

     •  Monitor the downstream manhole of the sanitary sewer system for
        evidence of dyed water.

     •  Measure the flows in the manhole before and during the dye-water
        testing. As an alternative, the flows can be simultaneously measured
        at both the upstream and downstream manholes during  the test.

     •  Record the location of storm drains and sanitary sewer lines being
        tested; the time and duration of tests; the manholes and the flow
        rates where the flows are monitored; the observed presence, concentra-
        tions and travel time of the dyed water into the flow monitoring
        manholes; and the soil characteristics (WPCF,  1983).

     First-hand visual observation of conditions is possible in large  diameter
sewers that permit workmen to enter.  Physical proximity to  the pipeline
interior enables workman to observe structural conditions, condition of
joints, location and nature of deposits and debris, and locations  of points of
infiltration.  Worker safety is an important consideration under such
conditions (WPCF, 1983).

     Television inspection is accomplished by using closed circuit systems
specifically designed for sewer inspection.  There are several configurations
                                     11-17
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of closed-circuit systems for sewer inspections, each of which have in common
the following (WPCF, 1983):

     •  Power for operation generated on-site

     •  Power control

     •  Transport winches

     •  Video (color, if possible) and lighting control

     •  Recording and documentation

     •  Radio communication

     Television inspection provides a video screen picture of pipeline being
inspected to an operator in a nearby van.  The operator controls the speed of
movement along the pipeline and records details of conditions observed.  Most
systems also provide for videotape recording of the inspection for future
reference.

     Pipeline cleaning is necessary for efficient collection system operation
and for exposing pipe materials for television inspection.  All collected
sediment and debris should be removed from the line and disposed of at an
approved site.  Care should be taken during the cleaning to minimize transport
of deposits into downstream lines.  As extensive outline of sewer cleaning
methods can be found in WPCF (1982).  The procedures for the most common
methods are briefly described below.

     Mechanical scouring techniques include the use of power rodding machines
("snakes"), which pull or push scrapers, augers, and brushes through the
obstructed line (Figure 11-1).  "Pigs," bullet-shaped plastic balls lined with
scouring strips, are hydraulically propelled at high velocity through water
and sewer mains to scrape the interior pipe surface.

     Hydraulic scouring is achieved by running high-pressure hoses into sewer
lines through manholes and flushing out sections of the sewer.  This technique
is often used after mechanical scouring devices have cleared the line of solid
debris or loosened sediments and sludges that coat the inner surface of the
pipe.

     A bucket machine can be used to dredge grit or contaminated soil from a
sewer line (Figure 11-2).  Power winches are set up over adjacent manholes
with cable  connections to both ends of a collection bucket.  The bucket is
then pulled through the sewer until loaded with debris.  The same technique
can be used to pull "sewer balls" or "porcupine scrapers" through obstructed
pipes (Hammer, 1975).  Bucket dredging is also useful for collecting samples
of contaminated sediments, groundwater, or leachate that may have infiltrated
the lines.

     Suction devices such as pumps or vacuum trucks also may be used to clean
sewer lines of liquids and debris.  Again, manholes and fire hydrants provide
easy access for the setup and operation of such equipment.
                                     11-18
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                   FIGURE 11-1.
           POWER RODOING MACHINE
Clecninq tool
               Source: Hammer, 1975
                    11-19
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                                 FIGURE 11-2.
                   SCHEMATIC OF BUCKET MACHINE CLEANING
                        Power winch with
                         loading chute
      Truck for hauling
        •way debris
                         Roller
Bucket
                                  Source: Hammer, 1975

     Another method  of  sewer  pipeline cleaning is the use of hydrophilic
polymer foams and gels  that absorb  and physically bind liquid pollutants  in  a
solid elastromeric matrix  (Johnson, J.,  Chemical Research Division,  3m Com-
pany, personal communication,  March 1980).   These polymers are special
chemical grouts that  can either  be  applied  internally to pipelines or injected
through breaks in the line  from  the exterior.   Once the absorbent grout has
set (solidified), the solid grout/pollutant matrix can be hydraulically
flushed from the line.  The applications of any of these hydrophilic grouts,
whose formulations are  often  proprietary, are still in the developmental  and
testing stages.
     11.6.5  Operation, Maintenance,  and Monitoring
     Inspection and  cleaning  of  water and sewer lines are essentially oper-
ating and maintenance  activities.   Montoring for effectiveness of cleaning  may
be warranted upon  completion  and periodically thereafter to ensure ongoing
absence of contaminants  from  the pipeline.
     11.6.6  Technology  Selection/Evaluation
     Inspection  and  cleaning  of water and sewer lines is established  and
accepted technology  for  conventional applications.  Removal of hazardous
contaminants  from  pipelines may be afforded by conventional methods where
                                      11-20
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contaminants are associated with deposits or debris  such  as  sludge,  slime,  or
sediments.  Contaminants that are sorbed onto the pipe material may  not be  as
readily removed.  Information concerning the effectiveness of  conventional
methods in such cases is not available.
     11.6.7  Costs


     Inspection and cleaning of water lines can be accomplished by  a variety
of methods, and costs vary accordingly.  Television inspection and  light high-
pressure water cleaning (the minimum required in preparation  for  repairing  or
lining pipelines) typically costs $100 to $150 per hour, or $0.40 to $0.60  per
linear foot for a rate of progress of 2,000 feet per eight-hour day and $0.80
to $1.20 per linear foot at a rate of 1,000 feet per day.  (D'Angelo, T., Pipe
Maintenance Services, Inc., Exton, PA, personal communication, April 1985).
Costs for other inspection and cleaning methods are highly variable and
dependent on the type of pipeline and nature of the material  being  removed.

11.7  Rehabilitation of Water and Sewer Lines


     11.7.1  General Description


     Water and sewer lines that are in contact with contaminated  substances or
allow infiltration of contaminated water can be lined or sealed in-place with
chemically inert material in order to isolate the water being transmitted from
the contaminants. Available methods include the following:

     •  Insertion of a new pipe inside of existing pipe (sliplining)

     •  In-place forming of new pipe inside of existing pipe

     •  Point repairs of leaks and other defects.

     Sliplining involves sliding a flexible liner pipe of slightly  smaller
diameter into an existing circular pipeline and then reconnecting the service
connections to the new liner.  Polyethylene is the most common material used
for sliplining pipelines (WPCF, 1983).

     A patented system called "inversion lining" uses a flexible  lining
material that is thermally hardened.  Access to the pipeline  can  be made
through manholes or excavations.  After the lining system has been  installed
and cured, a special cutting device is used with a closed-circuit TV camera to
reopen service connections.  The system is available only through licensed
contractors (WPCF, 1983).

     Because inversion lining can be accomplished relatively  quickly and
without excavation, this method is particularly well-suited for repairing
pipelines located under existing structures or large trees.   It also is
particularly useful for repairing pipelines located under busy streets or


                                     11-21
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highways where traffic disruption must be minimized.  Because the liner
expands to fit the existing pipe geometry, this method is applicable  to  all
pipeline shapes.  The cured resin material is reportedly corrosion-resistant.
Inversion lining also affords minor structural reinforcement.  Inversion
lining may be used for misaligned pipelines or in pipelines with bends where
realignment or additional access is not required (WPCF, 1983).

     Inversion lining using water to cure the resins is generally used in
pipelines with diameters less than 57 inches and manhole-to-manhole segments
less than 1000 feet long.  Larger diameter pipelines (to 108 inches)  have been
lined by inversion techniques using air (WPCF, 1983).

     Inversion lining is relatively new in the U.S. and its cost-competitive-
ness has not yet been fully established (WPCF, 1983).  It is a patented  system
available only through a limited number of licensed contractors.

     Chemical grouting is commonly used for sealing leaking joints in
structurally sound sewer pipes.  Small holes and radial cracks can also  be
sealed by chemical grouting (WPCF, 1983).

     Chemical grouts are synthetic materials that are applied as low-viscosity
liquids and cure as flexible, form-fitting solids.  Commonly used chemical
grouts are acrylamide gel, acrylate polymer, and polyurethane gel (WPCF,
1983).
     11.7.2  Applications/Limitations


     Repairing and lining of water and sewer  lines  applies  to  lines  that  are
1) contaminated as a result of ongoing contact with contaminated  substances,
or 2) allowing the infiltration of contaminated water.  The application of
materials to the interior of the pipe should  resolve either or both  problems
if the materials are properly selected.  The  materials  used have  low suscepti-
bility to chemical degradation and have relatively  low  permeability  to water,
and would be expected to effectively isolate  sewage and water  flows  from
contaminated pipelines and seepage.  However, the repair  and lining  materials
and techniques were not developed for control of hazardous  contaminants and
there is no information available that addresses their  effectiveness under
these special circumstances.  Factors that  could adversely  affect the
performance and reliability of repairs and  lining are:  1)  incompatability of
repair materials and contaminants, and 2) permeability  of repair  materials
with respect to contaminants.

     Sliplining is used to rehabilitate extensively cracked pipelines,
especially lines in unstable soil conditions.  It is also used to rehabilitate
pipe installed in a corrosive environment and in areas  where sewer pipes  have
massive destructive root intrusion problems (WPCF,  1983).   The flexible liner
pipes have the advantage of being able to accoraodate a  normal  amount of future
settlement or, moderate horizontal or vertical deflection.
                                      11-22
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     If the existing pipeline joints are offset, service lateral taps are
protruding, or if the diameter of the pipeline has been significantly reduced
in some other manner, the liner pipe diameter may need to be much smaller than
the diameter of the existing pipeline.  Such conditions can limit the utility
of this method (WPCF, 1983).

     Premanufacturered sliplining pipe cannot be used in pipe that is signifi-
cantly "out of round," since its cross section must pass through that of the
existing pipe.  New pipe formed in-place cannot be used where the existing
pipe has low structural integrity, unless reinforcing is added in the forming
(generally limited to larger diameters where workmen can enter).

     Point repairs can be used where problems are confined to joints  or to
relatively few short sections of pipe.

     Chemical grouting is generally used to seal open pipeline joints and
cracks.  It does not improve the strength of a pipeline, and should not be
used when pipe is severely cracked, crushed, or badly broken.  Chemical
grouts, once applied, may dehydrate and shrink if the surrounding moisture is
reduced significantly.  Some joints and cracks may be difficult to seal
chemically using gel grouts when large voids exist outside the pipe joint and
extremely large quantites of grout may be required to seal the joint (WPCF,
1983).

     Inspection and cleaning of pipelines is generally necessary in prepara-
tion for rehabilitation.  These methods are addressed in Section 11.6.
     11.7.3  Design Considerations


     Design of water and sewer line rehabilitation consists primarily of
planning for the logistics of implementation.  Sections of pipeline to be
rehabilitated are identified based on television or other inspections.
Critical points of operation such as access manholes, base of operation, and
material storage are selected.  Methods of managing disruption of service
(water or sewer) and of surface activities such as traffic are also planned.
Affected parties are notified in advance of the planned work.


     11.7.4  Construction/Implementation Considerations


     Typical sliplining materials include high-density polyethylene (HOPE) and
fiberglass-reinforced pipe (FRP).

     Before installing a liner pipe, the existing pipeline should be inspected
by closed circuit TV to identify all obstructions such as displaced joints,
crushed pipe, and protruding service laterals to locate service connections.
The existing pipe is thoroughly cleaned immediately before sliplining begins
(WPCF. 1983).
                                     11-23
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     HDPE  sliplining is pulled  through existing  pipelines by a  cable that is
fed through the section to be  lined.  The cable  and pipe are advanced by a
winch and  pully assembly (see Figure 11-3).  An  approach trench is  excavated
at the  insertion end of the  existing pipe section to allow a gradual transi-
tion from  the ground surface, where sections of  HDPE pipe are heat  fused to
form a  continuous pipe to an opened section of pipe.  Several thousand feet of
water or sewer line can be sliplined in a single set-up of such an  operation
(Waste  Engineering and Management, 1983).  FRP can be sliplined in  a manner
similar to that used for HDPE,  although a combination of pushing and pulling
of the  pipe can be employed  (see Figure 11-3)  (A.O. Smith-Inland, undated).

     Wastewater flow in existing sewers may not  need to be interrupted during
insertion  of a sliplining as low flows may continue through the annular space
between the two pipes.  Alternatively, it may  be necessary to temporarily plug
the upstream lines and pump  the flow around the  section being lined using
above-ground piping (WPCF, 1983).  The annulus between the old  and  new
pipelines  is sometimes filled with grout where structural failure of the old
pipe could concentrate loads and cause problems  with the HDPE pipelines.

     In-place forming of new pipe inside of existing pipe is accomplished with
portland cement grout and mortar, chemical grouts, and synthetic resins.
                                    FIGURE 11-3.
                            SEWER SLIPLINING METHODS
           .WINCH ASSEMBLY
           VREMOTE MANHOLE
           OR ACCESS PIT
                                RAMP FOR TWO-WAY.
                                  INSERTION
                              .CABLE ATTACHED
                              TO SUIOE CONE
 MIN. OP
 12 X LINER  MIN. OP
 DIAMETER  2.5 XD
                                                                  LINER
                                                                  PIPE
       PIPE SUPPORT-
         ROLLER
                                    "PULL" METHOD
            .WINCH AS3AMBLY
                                           MINIMUM OP STANDARD PIPE LENGTH
                                           JOINING MACHINE
                                                       PUSH PLATE-
                         ' \CABLE PASSING THROUGH
              ' EXISTING PIPE   ALINING PIPE ANCHORED
            V REMOTE MANHOLE   T0 PUSH PUATE
            OR ACCESS PIT              „   _
                                    "PUSH" METHOD
       ^•LINER PIPE
•PIPE SUPPORTED ROLLER
                                   Source: WPCF, 1983
                                        11-24
-------
     Chemical grouts can be used to seal fractures and leaking joints to
waterproof points of infiltration/exfiltration.  Grout materials used for this
application include acrylamide, acrylate, urethane and polyurethane.

     The chemicals necessary to form acrylamide or acrylate gels are usually
mixed in tanks and pumped through separate hoses to the pipeline joint to be
sealed.  The water and catalyst solution initiates the chemical reaction when
mixed with the acrylamide solution.  Additives can be included in either
solution to help control shrinkage, reaction or "gel" time, and other
variables (WPCF, 1983).

     The two solutions are pumped through separate hoses to the point to be
sealed.  The solutions are mixed as they are injected into the leaking
opening, initiating the chemical reaction.  This reaction changes the two
solutions into a gel.  The gel time can be controlled from just a few seconds
to several minutes.  The grouts or gels stabilize soil around joints or cracks
by filling the voids (WPCF, 1983).

     Urethane grout materials form either an elastomeric gel, much  like the
acrylamide and acrylate gels, or a rubber-like foam.  Water is the  catalyst
for the urethane gel material.  Urethane gel seals pipeline joints  by forming
a collar within the pipe joint as well as by consolidating soils and filling
voids outside the joint (WPCF, 1983).

     Urethane gel is applied in essentially the same manner as the  acrylamide
and acrylate gels.

     Polyurethane foam differs from the gel grouts in that the foam is used to
form an in-place pipeline gasket and does not fill voids or stabilize the soil
outside of the pipe joint (WPCF, 1983).

     Small and medium diameter pipes can be grouted using a hollow  metal
cylinder with inflatable rubber sleeves on each end of a center band, called a
"packer."  An inflated packer can be used both to test and chemically seal a
pipeline joint.  A van is used as the operation and control center  for a TV
monitor, pumps, air compressors, and the feed system equipment.  A  closed-
circuit TV camera allows positioning of the packer at pipeline joints and
cracks for sealing.  The packer and the TV camera are pulled along  with a
cable from manhole to manhole, and the process is viewed on the TV  monitoring
screen in the van (see Figure 11-4)  (WPCF, 1983).

     The amount of grout needed to seal a defect depends upon the size of the
leak.  The gels usually are pumped until the grout solidifies; the  back
pressure will then indicate to the operator that the leak has been  sucessfully
sealed.  The rubber sleeves are deflated and moved to the next joint for
sealing (WPCF, 1983).

     For grouting large-diameter pipes, pressure grouting or manual placement
of oakum soaked with grout may be used.  Pressure grouting is accomplished
using pipe grouting rings or predrilled injection holes (Figure 11-5).
                                     11-25
-------
                                       FIGURE 11-4.
TYPICAL ARRANGEMENT FOR APPLYING CHEMICAL GROUT TO SMALL DIAMETER PIPE
                                          CHEMICAL, CATALYST, AND
                                       •'AIR PRESSURE FEED LINES: ALSO
                                       POWER SOURCE FOR TV CAMERA
                                                           WINCH
                                -MANHOLE ASSEMBLY
                                     ROLLER
                                     Source: WPCF, 1983
                                       FIGURE 11-5.
TYPICAL ARRANGEMENT FOR SEALING LARGE  DIAMETER PIPE WITH  GROUTING RINGS
                 CHEMICAL, CATALYST
                 AND AIR PRESSURE
                 FEED LINES
                                                 CONTROL
                                                 PANEL    -HAND-HELD  PROBE
                                                                   SEALING
                                                                   RIN6
                                      Source: WPCF, 1983
                                          11-26
-------
     Grouting using sealing rings requires the use of a small control panel,
chemical and water pumps, and various other accessories depending on the type
of sealing grout being used.  A worker must enter the line, manually place the
ring over the joint, and inflate the ring to isolate the joint.  Sealing grout
is pumped into the small void between the pipe wall and the face of the ring
through a hand-held probe.  As the pressure in the void increases, the grout
solution is forced into the joint and surrounding soil.  The catalyst solution
is injected and the grout cures, sealing the joint from infiltration  (WPCF,
1983).

     Linings and coatings can be used to protect pipelines from internal
corrosion.  Most linings, however, are integrated into the pipe when it is
made (WPCF, 1983).

     Reinforced shotcrete (gunite) is a mixture of fine aggegate, cement, and
water applied by air pressure using a cement ejector.  Compared to cement
mortar linings, gunite is denser and has a higher ultimate compressive
strength.  It also improves a pipeline's structural integrity.  Gunite adheres
well to other concrete and brick sewers and is more corrosion-resistant than
normal concrete.  It can be trowled to a finish to improve a pipeline's
hydraulic characteristics (WPCF, 1983).

     Gunite is well-suited for extremely deteriorated large sewers where
persons and equipment can work without restriction.  Long lengths of sewers
may be effectively renewed with little excavation and minimal traffic
disruption.

     Gunite can be applied under low wastewater flows; however, totally
dewatering the pipeline is more effective.  Welded wire mat or small diameter
rod reinforcing is used for structural gunite applications (WPCF, 1983).

     In-place forming with synthetic resins (inversion lining) can be
accomplished without excavation in most cases.  The reconstruction is done
through existing pipe access points, requiring only limited disruption of
surface conditions and activities.  A four-step installation process, shown in
Figure 11-6, can normally be accomplished in a matter of days  (Utz, 1983).  A
fiberfelt tube impregnated with a liquid resin is fed into an inversion
standpipe which has been erected on site.  The felt tube has an impermeable
coating on the outside which eases handling and provides a water barrier for
the inversion process  (insituform, undated).  The end of the tube is pulled
through the inversion standpipe, turned inside out and clamped to the stand-
pipe such that a leak-proof seal is established.  As more water is added to
maintain the weight of the column, additional tubing is fed into the stand-
pipe, and the impregnated tube snakes its way forward through the pipe being
rehabilitated (WPCF, 1983).

     The weight of the water presses the coated felt at the nose, inverts it,
and then presses the resin-impregnated side against the insides of the
existing pipe, leaving the smooth coated side as the new interior surface of
the rehabilitated pipe.   After the inverted tube reaches the next manhole or
other access point, the water is heated to cure the resin, forming an
impermeable new pipe within the old pipe.  The ends are cut off, the head of

                                     11-27
-------
                  FIGURE 11-6.
INVERSION LINING INSTALLATION PROCEDURE
                               INVERSION     ^

                  LINER ATTACHED  \TUBE    MATERIAL
                   TO HEADE-     V
                     PIPE
        2 VPIPE TO
        ^     BE LINED
                       STEP I
                       STEP 2
          HOT WATER(OR AIR)
          CIRCULATION HOSE
                       STEP S
  LINED PIPELINE RETURNED TO SERVICE AFTER THE CURED
  LINER HAS BEEN TRIMMED, THE INSTALLATION EQUIPMENT
  HAS BEEN REMOVED, AND ANY SERVICE CONNECTIONS HAVE
  BEEN  REOPENED

                       STEP 4
                 Source: WPCF, 1983
                      11-28
-------
water is released, and the operation is complete.  Service connections are
reinstated in non-man-entry pipes by means of remotely controlled cutting
device (insituform, undated).
     11.7.5  Operation, Maintenance, and Monitoring
     If properly implemented, lined, and repaired, water and sewer lines
should require no operation or maintenance beyond that required for other
lines.  Periodic monitoring for contaminants of concerns in water or sewage
should be conducted to determine whether leaking or other failure of the
measures  has occurred.
     11.7.6  Technology Selection/Evaluation


     Repairing and lining offer the advantage of eliminating contaminants
without the need for disruption of surface activities.  However, the presence
of contaminants in close proximity to water or sewage may be cause for ongoing
concern.  Because these technologies were not specifically developed for con-
trol of hazardous substances, their performance and reliability under such
special circumstances is neither certain nor can be fully evaluated with
available information.  Coordination of material selection with manufacturers
may be useful in determining material compatability.  Also, laboratory
bench-scale and/or field pilot-scale tests may be warranted to ensure that
effective, long-term isolation of contaminants can be affected.


     11.7.7  Costs
     Costs of sliplining water and sewer lines vary with the diameter and
depth of the pipeline.  Costs for relatively small diameter (less than
15-inch) HDPE sliplining projects range from $20 to $30 per linear foot
(D'Angelo, T., Pipe Maintenance Services, Inc, Exton, PA, personal
communication, April 1985; Metcalf, K. Norfolk, VA, personal communication,
April 1985).  Larger diameter sliplining projects are seldom undertaken and
must be costed on a project-specific basis.

     Inversion lining costs are normally given on a per-linear-foot basis for
initial television inspection, cleaning, by-pass pumping, and post-construc-
tion television inspection combined.  The following are representative unit
costs for typical inversion lining of sewer lines.

          Diameter (inches)            Cost (Linear Foot)

                 8                     $45-50
                10                     $47-52
                12                     $49-54
                                     11-29
-------
Reconnection of laterals typically costs $100 to $250 each, depending on
logistics and the number of laterals in a given project.  (Tice, M.,
Insituform East, Inc. Landover, MD, Personal communication, April 1985.)


     Grout repairs to sewer pipelines are generally accomplished by pumping
grout into a joint until soil voids are filled, as determined by back-
pressure.  A wide range of grout volumes can be pumped into a joint, and sewer
grouting work is typically conducted on a per-hour basis for manpower and
equipment ($100 to $150 per hour) and on a per-gallon basis for grout ($5 to
$10 per gallon  for chemical grout).
                                      11-30
-------
                                  REFERENCES
American Society of Civil Engineers (ASCE).  Pipeline  Design  for Water  and
Wastewater 1975. New York, NY.   127 pp.

American Society of Civil Engineers (ASCE).  1976.  Design  and Construction  of
Sanitary and Storm Sewers.  Manual of Practice no.  37.  New York,  NY.   331 pp.

Anderson, M., R.A. Cottier and G.E. Bellen.  1984a.  Point-of-Use  Treatment
Technology to Control Organic and Inorganic Contaminants, Part I.
Water Technology.  September 1984.  pp. 36-41.

Anderson, M., R.A. Cottier and G.E. Bellen.  1984b.  Point-of-Use  Treatment
Technology to Control Organic and Inorganic Contaminants,
Part II.  Water Technology.  October 1984.  pp. 41-45.

A.O. Smith-Inland, Inc.  undated.  1 1/3 Miles of  Red  Thread® Inserted  as
Water main Under Portland Harbor, Pipefacts File 120,  Little  Rock,  AR.   2 pp.

Association Francaise de Travaux en Souterrain (AFTES).   1975.  Recommenda-
tions for the Use of Grouting in Underground Construction,  trans,  by G.W.
Clough.

Comsumers Union of United States, Inc.  1984.  1985  Buyers Guide Issue.
Mount Vernon, NY.  pp. 82-85.

Fair, G.M. et al. 1971.  Elements of Water Supply  and  Wastewater Disposal.
John Wiley and Sons, Inc., New York, NY.  752 pp.

Godfrey, R.S.  1984.  1985 Means Building Construction Cost Data,  43rd  Annual
Edition.  Robert Snow Means Co. Inc., Kingston, MA.

Insituform of North America, Inc.  undated.  Design Guide for Pipeline
Reconstruction.  Memphis, TN. 6 pp.

Linsley, R. and J. Franzini.  1979.  Water Resources Engineering.   3rd  Ed.
McGraw-Hill Book Company, New York, NY.

Morrison, 1981.  If Your City's Well Water has Chemical Pollutants, Then What?
Civil Engineering.  Vol. 51, No. 9.  pp. 65-67.

Perry,  D. L. et al.  1981.  Development of Basic Data and Knowledge Regarding
Organic Removal Capabilities of Commercially Available Home Water  Treatment
Units Utilizing Activated Carbon, Phase 3/Final Report.  EPA  Contract No.
68-01-4766.  Gulf South Research Institute.  Prepared  for:  Criteria and
Standards Divison, Office of Drinking Water, U.S. Environmental Protection
Agency.  October 23, 1981.  74 pp.
                                     11-31
-------
                            REFERENCES (continued)
National Sanitation Foundation (NSF) Drinking Water Treatment Units, Health
Effects.  Standard Number 53.  Ann Arbor, MI.  11 pp. and appendices.

Taylor, R. H., M. J. Allen and E. E. Geldreich.   1978.  Testing of Home Use
Carbon Filters.  Presented at AWWA Water Quality  Technology Conference.
Louisville, KY.  December 4, 1978.  9 pp.

Utz, John H.  1983.  Solving a Difficult Sewer Rehabilitation Problem.  Public
Works.  March 1983.  pp. 59-60.

Water/Engineering and Management.  1983.  Sliplining Water Mains Overcomes
Leakage.  February, 1983.  pp. 14-15.

Water Pollution Control Federation (WPCF).   1983.  Existing Sewer Evaluation
and Rehabilitation.  Manual of Practice FD-6.  Washington, D.C.  106 pp.

Water Pollution Control Federation (WPCF) 1982.   Operation and Maintenance of
Wastewater Collection Systems.  Manual of Practice No. 7. Washington, D.C.
                                      11-32
-------
                                  APPENDIX A

                                     INDEX
 Accessibility
      in Data Needs 2-5

 Acids
      in compatibility testing 7-26
      and  biodegradation 9-5

 Acrylamides
      as grout 5-98, 5-99, 5-100,
      5-101

 Activated carbon 10-3, 10-49, 11-5,
      10-121

 Activated sludge 10-10

 Adsorption 10-121

 Aeration  10-11

 Aerobic 6-1, 9-2, 9-3, 9-5, 9-15,
     9-34, 10-10

 Air pollution controls 4-1 to 4-0,
     10-137

 Air quality
     in climatology, data needs 2-5
     in specific site problems 2-4

 Air stripping 10-48

 Alcohols
     and  biodegradation 9-5
     and  toxicity to microbes 9-11

 Aldehydes
     and  biodegradation 9-5
     and  toxicity to microbes 9-11

Aliphatic alcohols
     as floating immiscible liquids 4-2

Alkanes
     and biodegradation 9-5
Alkyl halides
     and biodegradation, 9-3, 9-5

Amides
     and biodegradation 9-5
Amines
     and biodegradation 9-5
     and toxicity to microbes

Anaerobic 6-1, 9-2, 9-3, 9-5, 9-28

Anganochlorine
     in waste analysis 7-28

Aquifer
     artesian 5-14
     confined 5-5, 5-8, 5-11, 5-19
     data needs 2-5
     heterogeneous 5-5, 5-7
     homogeneous 5-5
     unconfined (water table) 5-5,
     5-8, 5-10, 5-15, 5-19

Aromatics
     and biodegradation 9-3, 9-5

Asphalt
     as a dust suppressant 4-5
     as mulch for revegetation 3-29

Augers
     hand 5-32, 5-33
     rotary bucket 5-33, 5-35, 5-44
     spiral 5-33, 5-35, 5-44

Backfilling
     and subsurface drains 5-71
     and slurry walls 5-89

Backhoes 7-2 to 7-6, 7-22, 8-2, 8-5,
     8-32, 8-35

Barriers
     and pumping 5-39
     and subsurface drains 5-47 to
     5-49, 5-51, 5-53
                                     A-l
-------
                            APPENDIX A (Continued)
     low permeability 5-1, 5-55 to
     5-59
     concrete 3-4
     bituminous membranes 3-4
     subsurface 5-83 to 5-113
Bases
     in compatability testing 7-26
     in pretreatment 7-27

Basket centrifuges 10-82

Bedrock
     in site geology data needs 2-5
     fractured or jointed 5-2

Belt filter presses 10-91

Benches 3-3, 3-52 to 3-56

Bentonite 3-7
     and slurry walls 5-83, 5-93
     5-96
     for wells 5-25

Berms 3-3, 3-12, 3-36 to 3-40, 8-48

Biological towers 10-11

Biological treatment 10-10

Bioreclamation 9-1 to 9-39

Biphenyls
     and biodegradation 9-3, 9-5

Bitumen 3-7

Block displacement 5-112

BOD/COD ratio 9-3, 9-4

Bottom ash
     and soil treatment 3-7

Bottom sealing 5-112, 5-113

Bucket factor 7-6

Bucket ladder dredge 8-2, 8-6, 8-7
Butyl alcohol
     as floating immiscible liquid 4-2

Butyl rubber
     and synthetic membranes 3-7,
     3-12, 3-16, 7-35
Capping
     general 3-1, 3-2 to 3-12, 6-28
     multi-layered 3-5 to 3-8, 3-9
     single-layered 3-5, 3-9

Carbon dioxide 6-1

Carboxylated styrene-butadiene copol-
     omer as dust suppressant 4-5

Casing
     for wells 5-23, 5-31, 5-33, 5-37

Cercla 1-1, 2-1

Cement
     Portland 3-7, 5-83, 5-92

Cement-based solidification 10-106

Centrifuges 10-82

Channels 3-1, 3-3, 3-40 to 3-52

Chelation
     and chemical treatment 9-36,
     9-43, 9-45, 9-46

Chemical Composition
     in waste characteristics,
     data needs 2-5
     in technology selection 2-7

Chemical stabilizers 3-7

Chemical treatment 9-39 to 9-61

Chlorinated Polyethene
     and synthetic membranes 3-7,
     3-12, 3-16

Chromium
     as alloy 7-14
                                     A-2
-------
                            APPENDIX A (Continued)
Chutes 3-1, 3-3, 3-57 to 3-63

Circulating Bed Combustion 10-135

Clamshells 7-6, 7-22, 8-2 to 8-4,
     8-32, 8-35

Clarifiers 10-72

Clean Water Act
     in remedial action alternatives
     2-10

Climatology
     in data needs 2-5

Cofferdams 8-21 to 8-25

Coke tray aerator 10-49

Compatibility testing 7-25 to 7-27

Cone of depression 5-8, 5-9, 5-12,
     5-18

Cone of impression 5-18

Contour furrowing 3-21

Costs
     of activated carbon units 10-8
     of activated sludge 10-17
     of active gas control 6-25 to
     6-27, 6-31
     of airstripping 10-52
     of benches and terraces 3-56,
     3-82
     of bioreclamation 9-35 to 9-39
     of capping 3-11, 3-12
     of cement-based solidification
     10-108
     of centrifuges 10-87
     of channels and waterways 3-52,
     3-82
     of chemical clarification 10-35
     of chutes and downpipes 3-57,
     3-82
     of cyclones 10-71
     of dikes and berms 3-40, 3-82
of dredging 8-36 to 8-42, 8-46
of dust suppressants 4-5, 5-6
of excavation equipment 7-6,
7-8, 7-9, 7-10
of filtration 10-97
of floating covers 3-19
of grading 3-24 to 3-26
of ground freezing 9-64
of grouting 5-103, 5-104, 5-109
of heavy metal precipitation
10-29
of hydraulic classifiers 10-66
of hydroxide and sulfide
precipitation 10-30
of incineration 10-141
of in-situ treatment 9-35, 9-59
of in-situ vitrification 9-62
of ion exchange 10-39
of levees and floodwalls 3-79,
3-82
of liners 7-35
of microencapsulation 10-116
of neutralization 10-47
of off-site disposal 7-25
of on-site disposal 7-38
of oxidation 10-55
of passive gas control 6-12
to 6-14
of permeable treatment 9-60
of polymer addition 10-31
of polypropylene spheres 4-3
of pumping 7-15
of reduction 10-56
of remedial action
alternatives 2-11 to 2-13
of revegetation 3-31 to 3-35
of reverse osmosis 10-44
of sedimentation basins/ponds
3-74, 3-82
of sediment treatment 8-46
of seepage basins and ditches
3-67, 3-82
of sewer line cleaning and
inspection 11-21
of sewer line rehabilitation 11-29
of sewer line replacement 11-14
of sheet piling 5-112
of silicate cement solidification
10-111
                                     A-3
-------
     of slurry walls 5-92, 5-93, 5-97
     of spiral classifiers 10-68
     of subsurface drains 5-73 to 5-82
     of surface water controls 3-80 to
     3-85
     of surfactant layers 4-3
     of thermoplastic solidification
     10-114
     of vacuum loaders 7-16
     of well systems 5-40 to 5-46
     of wind screens 4—7

Covers
     synthetic 4-8
     and sediments 8-49 to 8-54

Cranes 7-2, 7-6 to 7-8, 7-22

Cross-flow tower 10-49

Cutterhead Dredge
     and hydraulic dredging 8-9,
     8-32, 8-35

Cyanides
     in compatibility testing 7-26
     in pretreatment 7-27
     in waste analysis 7-28

Cyclones 10-68

Darcy's Law 5-8, 9-19

Data needs
     in site-specific
     characteristics 2-5

Dessication Caps 5-94

Detoxification 9-52

Dewatering
     in subsurface drain
     installation 5-69, 5-75

Dewatering lagoons 10-80

Diaphragm Walls 5-97
APPENDIX A (Continued)

             Diaphragm filters 10-96

             Diffused air basin 10-49
             Dikes 3-1, 3-3, 3-36 to 3-40,
                  8-48

             Disposal
                  of wastes 7-1 to 7-40
                  off-site 7-24 to 7-30
                  on-site 7-30 to 7-38

             Distillation 11-5

             Ditches 3-1, 3-2, 3-3, 3-63 to 3-67

             Diversion channels 3-1

             Diversion (channel) 3-42, 3-43

             Diversion Dikes 3-38, 3-39, 3-40

             DOT
                  and transportation of
                  wastes 7-29

             Downpipes 3-1, 3-3, 3-57 to
                  3-63

             Dozers 7-2, 7-8, 7-9, 7-22

             Dragline 7-2, 7-6, 7-7, 7-8,
                  7-22, 8-2, 8-4, 8-5,
                  8-32, 8-35

             Drains
                  interceptor 5-51 to
                  5-55, 5-82
                  relief (parrallel) 5-51,
                  5-55 to 5-59
                  subsurface 5-1, 5-46 to
                  5-82, 9-25
                  installation 5-70 to 5-72

             Drawdown 5-8, 5-9, 5-12, 5-15,
                  5-17, 5-21, 5-22, 5-25,
                  5-30
                  in plots 5-19, 5-20, 5-21
                                     A-4
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                            APPENDIX A (Continued)
Dredging
     mechanical 8-2 to 8-6, 8-32,
     80-35
     hydraulic 8-7 to 8-17,
     8-32, 8-35
     pneumatic 8-17 to 8-20,
     8-32, 8-35

Drilling
     rotary 5-32, 5-3A, 5-36, 5-44
     cable tool 5-34, 5-44

Drums
     and transportation of
     wastes 7-29

Dust suppressant 4-4 to 4-6

Dustpan dredge
     and hydraulic dredging
     8-10, 8-32, 8-35

Electroosmosis 10-80

Embankments 3-2

Encapsulation 10-115

Envelope
     and subsurface drains
     5-47, 5-62, 5-64, 5-71
     and leachate collection 7-34

EP Toxicity
     in waste analysis 7-28

Epichlorohydrin rubbers
     and synthetic membranes 7-35

Epoxides
     and biodegradation 9-5

Epoxy
     as grout 5-100

Erosion
     control of 3-1, 3-3, 3-7,
     3-8, 3-19. 3-20, 3-24, 3-36,
     3-52, 3-57
Esters
     and biodegradation 9-5

Ethylene propylene rubber
     and synthetic membranes
     3-7, 3-12, 3-16

Evapotranspiration 3-5, 3-9
     in climatology, data needs
     2-5

Excavation
     general 7-1 to 7-24
     equipment 7-2 to 7-16

Feasibility study (FS) 1-1, 2-2,
     2-3

Fermentation 9-3, 9-5

Filters
     and subsurface drains
     5-62, 5-71

Filter pack
     for wells 5-24, 5-25, 5-30,
     5-31, 5-37

Filtration 10-19, 10-91

Flaring 10-118

Flammability
     in compatibility testing 7-27

Flash point
     in waste analysis 7-28

Floating covers 3-13 to 3-19

Flocculation 10-22

Flooding
     protection from 3-2, 3-3,
     3-74 to 3-79

Floodplain
     in surface water,
     data needs 2-5
                                     A-5
-------
                            APPENDIX A (Continued)
     in disposal requirements
     7-30

Floodwalls 3-1, 3-2, 3-3,
     3-74 to 3-79

Flood control dikes 3-2

Flow
     equilibrium (steady state)
     5-8, 5-10
     non-equilibrium 5-8
     laminar 5-8
     and velocity distribution
     plots 5-19

Fluidized bed incinerator
     10-129

Flumes 3-1, 3-57

Flyash
     and soil treatment 3-7
     and slurry walls 5-96

Fugitive dusts/emissions
     4-1, 4-4 to 4-8, 7-20

Furnace slag
     and soil treatment 3-7
     and slurry walls 5-96

Gabions 3-64

Gas
     collection system 3-5,
     3-16, 3-17, 4-4, 6-14
     to 6-25
     migration 2-4, 3-30, 4-4,
     3-30, 6-2
     emissions 4-1 to 4-4, 6-28
     controls 6-1 to 6-32
     organic 6-1
     detectors 6-9, 7-23
     passive perimeter controls
     6-21 to 6-14
     active perimeter controls
     6-14 to 6-24
     extraction wells 6-14 to
     6-25
     collection headers 6-14
     to 6-25
     treatment or utilization
     6-14 to 6-25
     active interior controls
     6-26 to 6-31
     cylinders 7-24

Gaseous waste treatment 10-118
Geology
     in data needs 2-5

Geotextiles
     as capping 3-12
     as dust suppressant 4-5
     and subsurface drains
     5-62, 5-72

Classification 10-116

Glycols
     and biodegradation 9-5

Grade control
     in subsurface drains 5-69

Grading 3-1, 3-3, 3-19 to 3-26

Grapples 7-6

Gravel pack (see filter pack)

Gravity collection systems  5-1

Gravity separation 10-47

Gravity thickening 10-77

Gravity underdrainage  10-80

Grizzlies  10-58

Ground freezing  9-61

Ground leaching
     (see  soil flushing 9-45)
                                     A-6
-------
Groundwater
     in data needs 2-5

Groundwater
     monitoring 7-37
     temperatures 9-9

Groundwater
     extraction 3-4
     containment 3-4

Groundwater
     controls 5-1 to 5-118
     diversion 5-1
     pumping 5-1 to 5-46

Groundwater
     barriers 5-5

Groundwater quality
     in specific site
     problems 2-4
APPENDIX A (Continued)

             Heat recovery 10-138

             Henry's law 9-19

             Herbicides
                  and biodegradation
                  9-3, 9-5

             Heterogeneous aquifers 5-5

             High temperature fluid wall
                  10-135

             Hoists 7-6

             Homogeneous aquifiers 5-5

             Hopper dredges
                  and hydraulic dredging
                  8-11, 8-32, 8-35
Grouting
     and subsurface barriers
     5-97 to 5-109
     cement 5-97
     clays 5-98, 5-99
     bentonite 5-98, 5-99
     silicates 5-98, 5-99
     organic ploymers 5-98, 5-99
     curtains 5-103 to 5-109
     port method 5-105, 5-107
     and bottom sealing 5-112
     and sediments 8-55, 8-56

Grouting
     for wells 5-24, 5-37, 5-38

Gyratory screens 10-59

Halogens
     in compatibility testing
     7-26

Haulers 7-9, 7-10, 7-22

Head 5-8, 5-9, 5-20, 5-26,
     5-27, 5-28, 5-56
             Hydraulic barriers (boundary
                  conditions) 5-8, 5-16,
                  5-17, 5-18, 5-19, 5-20

             Hydraulic classifiers 10-63

             Hydraulic conductivity 5-2,
                  5-8, 5-10, 5-51
                  in well selection 5-5, 5-7,
                  5-19, 5-38, 5-58, 5-73

             Hydraulic gradient 5-2, 5-8,
                  5-59, 5-60

             Hydrocarbons
                  and biodegradation 9-3, 9-5

             Hydrocyclones 10-68

             Hydrogen sulfide 6-1, 6-8, 9-50

             Hydrogen peroxide
                  and bioreclamation
                  9-15, 9-17

             Hydrolysis 9-40, 9-42, 9-52

             Hydrosieve 10-63
                                     A-7
-------
                            APPENDIX A (Continued)
Hydroxy compounds
     and biodegradation 9-5

Hypalon
     and synthetic membranes
     3-7, 3-12, 3-16, 3-19, 6-8

Immobilization 9-47

Impoundment basin 10-72

Incineration 7-25

Infiltration
     prevention of 3-1, 3-3, 3-8,
     3-20, 3-26, 3-44, 5-2
     through capping 3-4, 3-5

In-situ heating 9-61

Interceptor dike 3-36, 3-37, 3-38

Inversion lining 11-22

Ion exchange 10-36, 11-5

Jetting
     and well installation 5-33,
     5-35, 5-36, 5-44

Ke tones
     and biodegradation 9-5
     and toxicity to microbes 9-11

Lagoon
     covers 3-2, 3-3

Landfills 7-25, 7-30 to 7-38

Latex
     as dust suppressant 4-5

Leachate
     in specific site
     problems 2-4

Leachate
     prevention 5-1
     control 5-101
Leachate
      collection 7-32, 7-33,  7-36

Levees  3-2,  3-3,  3-12,
      3-74  to 3-79,  7-33

Lifters 7-6

Lignosulfonate
      as dust suppressant  4-5

Lime
      and soil treatment 3-7

Liners
      natural 3-4  to 3-6,  3-12,
      7-20, 7-30 to  7-32,  7-33,  7-36
      synthetic 3-4, 3-5,  3-6, 3-7,
      3-10, 3-11,  3-12, 3-13, 3-16,
      4-1,  7-30 to 7-32, 7-33,
      7-34, 7-35
      admixed 3-4, 3-5, 3-6,  3-12,
      7-32, 7-33

-Liquid  injection  10-123

Liquid  migration
      requirements 3-2

Loaders 7-2, 7-8, 7-9,
      7-15, 7-16,  7-22

Magnets 7-6

Manholes
      and subsurface drains
      5-62, 5-65,  5-81

Manning formula 3-44, 3-49,  3-50

Methane 6-1, 6-8

Methanogenic processes
      and bioreclamation 9-2,
      9-30, 9-37

Microencapsulation  10-115

Mobile  incineration 10-131
                                     A-8
-------
                               APPENDIX A (Continued)

   Molten salt  incineration  10-131

   Monitoring wells  3-4, 3-11,  5-72
   National contingency plan (NCP)
       1-1, 2-1, 2-8

   Native vegetation
       in data needs 2-5

  Neoprene
       and synthetic membranes
       3-7, 3-12, 7-35

  Neutralization 9-52, 10-45

  NIOSH 7-21

  Nitrate
       and  anaerobic  bioreclamation
       9-30, 9-31

  Nutrients
       and  bioreclamation 9-22
       to 9-23

  Nitrites
      and biodegradation 9-5

 Nitro compounds
      and biodegradation 9-5,
      9-32

 Nitrogen 6-1,  9-22

 Octanol-water  partition
      coefficients  9-46

 Organophosphates
      and biodegradation 9-3,
      9-5

 OSHA  7-21

Osmosis 10-40

Oxidation 9-3,  9-5, 9-38,
     9-41,  9-42, 9-53, 9-54
 Oxidizing agents
      in compatibility testing
      7-26
 Oxygen 6-1, 6-8, 7-23, 9-15
      and requirements for
      bioreclamation 9-3, 9-15
      to 9-22

 Packed tower 10-48

 Packer 5-28, 5-37

 PCS
      and incineration 7-25
      in compatibility testing
      7-26
      in waste analysis 7-28
      and sediment treatment
      8-45
 PCE
      and  biodegradation  9-2,  9-30
 Permeability 5-8,  5-25
     of  slurry walls  5-87,
     5-88,  5-94
     of  grouts 5-99
     and gas control  systems
     6-4, 6-7

 Permeable treatment bed
     9-56

 Peroxides
     in  compatibility testing
     7-26

 Pesticides
     and biodegradation 9-2,
     9-30

 PH
     in waste analysis 7-28
     in bioreclamation
     monitoring 9-9, 9-32

Phenolic grouts 5-99, 5-100
                                     A-9
-------
                            APPENDIX A (ContinuedO
Phenols
     and biodegradation 9-3,
     9-5

Phosphates
     and bioreclamation
     9-8, 9-22, 9-32

Phytotoxic 3-26, 3-28

Piezometric surface 5-14

Piezometers 5-72

Pipes
     and subsurface drains
     5-47, 5-59 to 5-62, 5-70,
     5-71, 5-79
     and leachate collection
     systems 7-34

Piping
     and liners 3-8, 7-3

Plasma Arc Torch 10-133

Plume
     containment 5-1, 5-2,
     5-16, 5-19, 5-47, 5-54
     prevention 3-4
     removal 5-1, 5-2, 5-47
     diversion 5-5, 5-6
     non miscible 5-17
     floating contaminants
     5-12
     delineation 5-46

Point dumping
     and sediment covers
     8-50, 8-51

Polydimethyl siloxane
     as floating immiscible
     liquid 4-2

Polyester
     and silt curtains 8-28
     and filters 5-62
     as grout 5-100, 5-101
                                     A-10
Polyethylene
     and synthetic membranes
     3-7, 6-8, 7-17, 7-35
     and filters 5-62

Polyhydrldes
     and biodegradation 9-5

Polymerization
     and chemical treatment
     9-36, 9-42, 9-51

Polyolefin
     and synthetic membranes 3-7

Polypropylene
     as filters 5-62
     and synthetic membranes 7-35
     spheres 4-2, 4-3
     as pump coating 7-11

Polyvinyl chloride (see PVC)

Ponds 3-2, 3-3, 3-67 to 3-74

Potentiometric surface
     map 5-17, 5-23, 5-51

Precipitation 9-47, 9-51, 10-22
     in climatology,
     data needs 2-5, 3-9

Precipitation
     and chemical treatment
     9-36, 9-43, 9-50

Pretreatment
     of wastes 7-27

Proctor Density 3-21

Production rates
     backhoes 7-4, 7-6, 8-6
     cranes and attachments 7-6, 7-8
     dozers and loaders 7-9

Production rates
     clamshells 8-2
     draglines 8-5
     pneumatic dredges 8-17
-------
                            APPENDIX A (Continued)
Public health
     in screening remedial
     action alternatives
     2-8, 2-11

Pumps
     submersible 5-25, 5-42, 7-14
     vertical lineshaft 5-26
     performance curves 5-27
     ejector (jet) 5-28, 5-42
     suction (vacuum) 5-5,
     5-30, 5-42
     centrifugal 7-11
     reciprocating 7-11 to 7-13
     diaphram 7-11, 7-12
     bellow 7-11, 7-12
     piston 7-11, 7-12
     positive displacement
     7-13
     gear 7-13
     flexible impeller 7-13
     flying vane 7-13
     immersion 7-14

Pumpdown
     and sedmiment covers
     8-50, 8-51, 8-52

Pump Test 5-8, 5-19

Pumping
     equilibrium vs non-
     equilibrium 5-17, 5-20

Pumping
     rates 5-22
     and groundwater controls
     5-1 to 5-46

PVC (Polyvinylchloride)
     and synthetic membranes
     3-7, 3-12, 6-8, 7-35
     dand filters 5-62
     and silt curtains 8-28
     as pump coating 7-11
PVDF
     as pump coating 7-11
 Pyrolysis  10-135

 Radioactivity
     meters  7-23
     in  compatibility
     testing 7-26
     in  waste analysis
     7-28

 Radius of  influence
     of  a  well 5-2,  5-8,  5-9,
     5-10, 5-12, 5-17,  5-19, 5-20

 Rainfall
     in  climatology,
     data  needs 2-5
     events  (storms) 3-44

 RCRA
     and disposal regulations 3-5
     and capping design 3-5
     and off-site disposal 7-24
     and incineration 7-25
     and transporatation 7-29
     and on-site disposal 7-30, 7-37
     and landfill liner systems 7-32
     and leachate collection systems
     7-32
     and ground water monitoring 7-37
     in remedial action alternatives
     2-10
     landfill  closure requirements
     3-2

 Reactors 10-137

 Reamers 5-35

 Recharge
     in groundwater characteristics,
     data needs 2-5

 Recharge
     rates 5-8

Reduction
     and chemical treatment
     9-38,  9-43, 9-54,  10-55
                                     A-ll
-------
 Remedial  Investigation
      (RI)  1-1

 Remedial  technology
      catagories 2-4
      data  needs 2-5, 2-6

 Removal 7-1 to 7-24

 Resins 10-36
      as grout 5-98
      as dust suppressant 4-5
      as mulch for revegation 3-29

 Revegetation 3-1, 3-3, 3-19, 3-26
      to 3-32
 Reverse osmosis 10-40, 11-5

 Revolving  screens 10-59

 RI/FS 1-1, 2-1, 2-2

 Rock grouting 5-101 to 5-103

 Rotating biological contacter
     10-11

 Rotary kiln 10-126

 Roughness coefficient 5-60

 Runoff
     prevention of 3-1,  3-3, 3-36
     interception of 3-1, 3-3, 3-52
     diversion of 3-36,  3-40, 3-42,
     3-52, 3-57,  3-79

 Safe Drinking Water Act
     (SDWA)
     in remedial  action
     alternatives 2-10

Safety
     in remedial  action
     alernatives  2-10
     field personnel 7-20
APPENDIX A (Continued)

             Salts
Salts
     and soil treatment 3-7
                  and bioreclamation
                  9-23, 9-24

             Scarification 3-21

             Scrapers 7-10, 7-22

             Screens 4-6, 4-7, 5-37

             Screen
                  for wells 5-23 to 5-25,
                  5-31, 5-33, 5-38, 5-43

             Screens and sieves 10-58
                  grizzlies 10-58
                  vibrating 10-59
                  gyratory 10-59
                  revolving 10-59
                  fixed 10-62

             Sediments
                  removal 8-1 to 8-42, 8-44
                  treatment 8-43 to 8-57
                  in-situ control 8-47 to 8-57
                  covers 8-49 to 8-54
                  surface sealing 8-54 to 8-56
                  in-situ grouting 8-56

             Sediments, contaminated
                  in specific site
                  problems 2-4
                  removal and
                  containment of
                  8-1 to 8-60

             Sediment trap 3-64, 3-65

             Sedimentation 10-23, 10-32

             Sedimentation basins 3-2,
                  3-3,  3-67 to  3-74, 10-32

             Seepage basins 3-2, 3-3,  3-63
                  to 3-67

             Seismic history
                  in site geology,
                  data  needs  2-5
                                     A-12
-------
                            APPENDIX A (Continued)
Settling basin 10-71

Sewer lines, contaminated
     in specific site
     problems 2-4

Sewer lines 11-1
     replacement 11-9
     inspection and
     cleaning 11-14
     rehabilitation 11-21

Sheet piling 5-109 to 5-112

Silicate based solidification 10-108
Silicon
     as alloy 7-14

Silt curtains 8-28 to 8-31

Site-specific characteristics
     in technology screening 2-3
     in geology 2-5
     in ground water 2-5
     in surface water 2-5
     in climatology 2-5
     in in-situ treatment
     9-44

Slings 7-6

Sliplining 11-22

Slurry Walls 5-2, 5-83 to
     5-97
     soil-bentonite 5-83 to
     5-92
     cement-bentonite 5-92
     to 5-97
     as gas migration
     barriers 6-7
Soils
     in data needs 2-5
     treatment for liners 3-7
     tests 3-9
     characteristics for
     revegetation 3-28
Soils, contaminated
     in specific site
     problems 2-4

Soil flushing
     and chemical treatment
     9-36, 9-41, 9-43, 9-45 to 9-46

Soil water partition
     coefficient 9-46

Solid bowl solidifications 10-108

Solidification 9-51, 10-106

Solids separation 10-57

Solution mining (see soil
     flushing)

Solvent flushing (see soil
     flushing)

Sorbents 10-111

Sorptive resins 10-36, 10-122

Specific capacity 5-8

Specific gravity
     in waste analysis 7-28

Specific yield 5-22

Spiral classifier 10-66

Stabilization 9-51, 10-106

Stage-down
     and grout curtains
     5-105, 5-107

Stage-up
     and grout curtains 5-105,
     5-107

Stagnation point 5-19, 5-22
                                     A-13
-------
Storage coefficient(s)
     5-8, 5-17, 5-19, 5-20
APPENDIX A (Continued)

             Swales 3-42, 3-43, 3-44

             TCE
Submerged diffuser system
     and sediment covers 8-52,
     8-54

Subsurface barriers (see
     Barriers, subsurface)

Suction Dredge
     in hydraulic dredging
     8-8, 8-32, 8-35

Sulfates
     and bioreclamation 9-31,
     9-32

Sulfides
     in combatibility testing
     7-26
     in pretreatment 7-27

Sulfur
     in waste analysis 7-28

Sumps 5-64, 5-66, 7-34

Superfund 2-1

Surface encapsulation 10-115

Surface water
     in data needs 2-5
     controls 3-1 to 3-88
     collection and transfer
     3-1, 3-3
     storage and discharge
     3-2, 3-3
     diversion and collection
     3-32 to 3-85, 7-20, 8-21

Surface water quality
     in specific site
     problems 2-4

Surfactants 9-46 to 9-48,
     9-49
                  and biodegradation 9-2,
                  9-3, 9-30

             Technology limitations
                  in technology screening
                  2-7

             Technology screening
                  in site characteristics
                  2-3, 2-5
                  in technology limitations 2-7
                  in waste characteristics
                  2-5, 2-7
                  in remedial action
                  alternatives 2-8

             Terraces 3-1, 3-3, 3-21,
                  3-52 to 3-56

             Thermal Destruction 10-123

             Thermoplastic elastomers
                  and synthetic membranes 7-35

             Thermoplastic solidification
                  10-113

             Thiols
                  and biodegradation 9-5
             TOG
                  and bioreclamation monitoring
                  9-32
             Topography
                  in data needs 2-5

             Toxic substance control act
                  in remedial action
                  alternatives 2-10

             Tracing 3-21

             Transmissivity (T) 5-8, 5-15,
                  5-17, 5-19, 5-20, 5-39, 5-45
                                     A-14
-------
                            APPENDIX A (Continued)
Trenches
     excavation 5-67 to 5-70

Trickling filter 10-11

TSCA 2-10

Turbitity control
     and sediments removal
     8-27 to 8-31

Universal soil loss equation
     3-8

Ure a-f o rmaldehyde
     as grout 5-100, 5-101

Ur ethanes
     as grout 5-99, 5-100
Vacuum assisted drying
     beds 10-80

Vacuum loaders 7-15, 7-16, 7-22

Vacuum pumping 10-80

Vapor detectors 7-23

Vegetable gum
     as dust suppressant 4-5

Venturi
     and ejector wells 5-28

Vibrating beam
     and grout curtains
     5-105, 5-107, 5-108

Vibrating screens 10-59

Viscosity
     in waste analysis 7-28

Vitrification 10-116

Wall stabilization
     and subsurface drains
     5-70
Waste characteristics
     in technology screening
     2-5, 2-7
     in specific site
     problems 2-4

Waste migration 3-4

Waste treatment
     in-situ 9-1 to 9-70

Water Spraying 4-7

Water supply 11-1
     contamination 11-1
     replacement 11-2
     treatment 11-4

Water table 5-8, 5-15,
     5-54, 7-33
Waterways 3-1, 3-3,
     3-40 to 3-52

Wedge bar screen 10-62

Wellpoints 5-1, 5-5, 5-7,
     5-30, 5-31, 5-43, 5-69
Wells
     suction 5-1, 5-5, 5-7
     ejector 5-1, 5-5, 5-7,
     5-26 to 5-30
     deep 5-1, 5-5, 5-7,
     5-23 to 5-26, 5-69
     extraction 5-2, 5-3,
     5-4, 5-16, 5-22, 5-46,
     5-47, 9-25 to 9-28
     injection 5-2, 5-4,
     5-16, 5-22, 9-25 to 9-28
Wells
     partially penetrating
     5-8, 5-12, 5-14
     design 5-17 to 5-23
     components 5-23 to 5-31
     driven 5-32, 5-33
     completion 5-37, 5-38
     development 5-38
                                     A-15
-------
                            APPENDIX A (Continued)
     installation 5-32 to 5-38
     maintenance 5-38, 5-39

Wet air oxidation 10-133

Wind fences/screens 4-6, 4-7

XR-5 3-16
                                     A-16
-------
                                  APPENDIX B

                               COPYRIGHT  NOTICE
Figure 3-15
Figure 3-21
Figure 3-22
Figure 3-23
Figure 3-24
Figure 3-30
Figure 3-31
Table 5-1
Figure 5-5
Table 5-5
Figure 5-6
Figure 5-7
From Tourbier, J.  and R. Westmacott.   1974.   Water  Resources
Protection Measures  in Land Development—A Handbook.   Used  by
permission of Water  Resource Center,  University  of  Delaware.

From Tourbier, J.  and R. Westmacott.   1974.   Water  Resources
Protection Measures  in Land Development—A Handbook.   Used  by
permission of Water  Resource Center,  University  of  Delaware.

From Tourbier, J.  and R. Westmacott.   1974.   Water  Resources
Protection Measures  in Land Development—A Handbook.   Used  by
permission of Water  Resource Center,  University  of  Delaware.

From Tourbier, J.  and R. Westmacott.   1974.   Water  Resources
Protection Measures  in Land Development—A Handbook.   Used  by
permission of Water  Resource Center,  University  of  Delaware.

From Tourbier, J.  and R. Westmacott.   1974.   Water  Resources
Protection Measures  in Land Development—A Handbook.   Used  by
permission of Water  Resource Center,  University  of  Delaware.

From Linsley, R. and J. Franzini,  1979.  Water Resources
Engineering, 3rd Edition.  Used by permission of McGraw-Hill
Book Company.  New York, N.Y.

From Tourbier, J.  and R. Westmacott.   1974.   Water  Resources
Protection Measures  in Land Development—A Handbook.   Used  by
permission of Water  Resource Center,  University  of  Delaware.

From Powers, J.P.  1981.  Construction  Dewatering:  A  Guide
to Theory and Practice.  Used by permission of John Wiley and
Sons, Inc.  New York, NY.

From Davis, S.N.and  R.J.M. Deweist.   1966.  Hydrogelogy.
Used by permission of John Wiley and  Sons, Inc.  New York,
NY.

From Johnson Division.  UOP, Inc.  1975.  Groundwater  in
Wells:  A Reference  Book for the Water Well Industry.  Used
by permission of Johnson Division, UOP, Inc.  St. Paul, MN.

From Davis, S.N.and  R.J.M. Deweist.   1966.  Hydrogelogy.
Used by permission of John Wiley and  Sons, Inc.  New York,
NY.

From Powers, J.P.  1981.  Construction Dewatering:  A  Guide
to Theory and Practice.  Used by permission of John Wiley and
Sons, Inc.  New York, NY.
                                     B-l
-------
                            APPENDIX B (continued)
Table 5-7
Figure 5-9


Table 5-9


Figure 5-10



Figure 5-11



Figure 5-12



Figure 5-14



Figure 5-15



Table 5-16
Figure 5-16a&b
Figure 5-16c
Modified from Lundy, D.A. and J.S. Mahan.  1982.  Manuscripts
originally printed in the proceedings of the National
Conference on Management of Uncontrolled Hazardous Wastes  -
1982.  Nov. 29 - Dec. 1.  Used by permission of Hazardous
Materials Control Research Institute.  Available from
Hazardous Materials Control Research Institute, 9300 Columbia
Blvd., Silver Spring, MD  20910.

From Freeze, R.A. and J.A. Cherry.  1981.  Groundwater.  Used
by permission of Prentice-Hall, Inc.  Englewood Cliffs, NJ.

From Church, H.K.  1981.  Excavation Handbook.  Used by
permission of McGraw-Hill Book Company, New York, NY.

From Davis, S.N.and R.J.M. Deweist.  1966.  Hydrogelogy.
Used by permission of John Wiley and Sons, Inc.  New York,
NY.

From Ferris, et. al.  1982.  As cited by Lohman, S.W.   1972.
Ground Hydraulics Geological Survey Professional Paper  708.
Used by permission of US Geological Survey, Reston, VA.

From Johnson Division.  UOP, Inc.   1975.  Groundwater in
Wells:  A Reference Book for the Water Well Industry.   Used
by permission of Johnson Division, UOP, Inc.   St. Paul, MN.

From Flint and Wailing, Inc.   1980.  Putting water to work
since 1866.  Technical  Information Brochure.   Used by
permission of Flint and Walling, Inc.  Kendallville, IN.

From Powers, J.P.  1981.  Construction Dewatering:  A Guide
to Theory and Practice.  Used by permission of John Wiley  and
Sons, Inc.  New York, NY.

Adapted from Jefferis,  S.A.  1981.  Bentonite-Cement Sluries
for Hydraulic Cut-offs.  In:  Proceedings of the Tenth
International Conference on Soil Mechanics and Foundation
Engineering.  Stockholm, Sweden.  June 15-19,  1981.  Used  by
permission of S.A. Jefferis.

From Johnson Division.  UOP, Inc.   1975.  Groundwater in
Wells:  A Reference Book for the Water Well Industry.   Used
by permission of Johnson Division, UOP, Inc.   St. Paul, MN.

From Powers, J.P.  1981.  Construction Dewatering:  A Guide
to Theory and Practice.  Used by permission of John Wiley  and
Sons, Inc.  New York, NY.
                                     B-2
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                            APPENDIX B  (continued)
Figure 5-22      From Giddings, T.   1982.  The Utilization  of  a Groundwater
                 Dam for Leachate Containment at a Llandfill Site.   In:
                 Aquifer Restoration and Groundwater Rehabilitation.   2nd
                 National Symposium  on Aquifer Restoration  and Groundwater
                 Monitoring.  May 26-28.  Used by permission of National Water
                 Well Assoc., Worthington, OH.

Figure 5-25      Adapted from Van Schlifgaarde, J.  1974. Drainage  for
                 Agriculture, Agronomy monograph number  17, pages 245-270.
                 Used by permission  of American Society  of  Agronomy.   Madison,
                 WI.

Figure 5-32      Adapted from Jefferis, S.A.  1981.  Bentonite-Cement  Slurries
                 for Hydraulic Cut-offs.  In:  Proceedings  of  the Tenth
                 International Conference on Soil Mechanics and Foundation
                 Engineering.  Stockholm, Sweden.  June  15-19, 1981.   Used by
                 permission of S.A.  Jefferis.

Figure 5-33      Adapted from Bowen, R.  1981.  Grouting  in Engineering
                 Practice.  2nd. Ed.  Used by permission  of John Wiley and
                 Sons,  Inc.  New York, NY.

Figure 5-35      From Soletanche, undated.  Soils Grouting.  Technical
                 Bulletin.  Used by  permission of Soletanche.  Paris,  France.

Figure 5-36      From Ueguhardt, L.C. et al.  1962.  Civil  Engineering
                 Handbook.  Used by  permission of McGraw-Hill  Book  Company.
                 New York, NY.

Figure 6-1       From Emcon Associates and Gas Recovery  Systems, Inc.  1981.
                 Landfill Gas - An Analysis of Options.   Published  by
                 permission of Emcon Associates.  San Jose, CA.

Figure 6-4       From Emcon Associates.  1980.  Methane  Generation  and
                 Recovery From Landfills.  Published by  permission  of  Ann
                 Arbor Science Publishers, Inc.  Ann Arbor, MI.

Figure 6-8       From Emcon Associates and Gas Recovery  Systems, Inc.  1981.
                 Landfill Gas - An Analysis of Options.   Published  by
                 permission of Emcon Associates, San Jose,  CA.

Figure 7-1       From Stubbs, E.W.   1959.  Handbook of Heavy Construction.
                 1st Edition.  Used by permission of McGraw-Hill Book  Company.
                 New York, NY.
                                     B-3
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                            APPENDIX B (continued)
Figure 7-4
Table 7-5
Table 7-6
Figure 8-3
Figure 8-10
Table 9-1
Figure 9-1
Figure 9-6
Table 9-7
Table 9-8
From Buecker, D.A. and M.L. Bradford.   1982.  Page 299.
"Safety and Air Monitoring Considerations of the Cleanup of  a
Hazardous Waste Site."  Manuscripts originally printed  in
Proceedings of the National Conference  on Management of
Uncontrolled Hazardous Waste Sites - 1984.  Used by
permission of Hazardous Materials Control Research Institute.
Available from Hazardous Materials Control Research
Institute, 9300 Columbia Blvd., Silver  Spring, MD  20910.

From Cope, F., G. Karpinski, J. Pacey and L. Stein.  Use of
Liners for Containment of Hazardous Waste Landfills.
Pollution Engineering.  Vol. 16. No. 3.  Used by permission
of Pudvan Publishing Co.  Northbrook, IL.

From Cope, F., G. Karpinski, J. Pacey and L. Stein.  Use of
Liners for Containment of Hazardous Waste Landfills.
Pollution Engineering.  Vol. 16. No. 3.  Used by permission
of Pudvan Publishing Co.  Northbrook, IL.

From Merritt, F.   1976.  Standard Handbook for Civil
Engineers.  Used by permission of McGraw Hill Book Company.
New York, NY.

From Alluvial Mining and Shaft Sinking  Co., Ltd. 1984,
Equipment and Services Brochure.  Used  by permission of
Alluvial Mining and Shaft Sinking Co.,  Ltd.  Basildon,
5S14-1EA, England.

From Lyman, Reehl and Rosenblatt.  1982.  Handbook of
Chemical Property Estimation Methods.   Used by permission of
McGraw-Hill Book Company.  New York, NY.

From Johnson Division.  UOP, Inc.  1975.  Groundwater in
Wells:  A Reference Book for the Water  Well Industry.   Used
by permission of Johnson Division, UOP, Inc.  St. Paul, MN.

From Jhaveri, V. and A.J. Mazzacca.  1983.  Bio-reclamation
of Ground and Groundwater by CDS Process.  Used by permission
of Groundwater Decontamination Systems.  Waldwick, NJ.

From Jamison, V.W., R.L. Raymond and J.O. Hudson.  1976.
Biodegradation of High-Octane Gasoline.  In:  Proceedings of
the Third International Biodegradation  Symposium.  Used by
permission of Elsevier Applied Science  Publishers.  Barking,
Essex 1G11, 8JU, England.

From Groundwater Decontamination Systems, Inc.  Report  1.
Experiments from Sept.  15 to Nov. 5.  Used by permission of
Groundwater Decontamination Systems.  Waldwick, NJ.

                    B-4
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                             APPENDIX B (continued)
 Figure  9-8
 Table  9-15
Table 9-19
Table 10-1
Table 10-2
Figure 10-3
Figure 10-4
Table 10-5
 From Sullivan,  J.M.,  D.R.  Lynch,  and I.K.  Iskandar.   1984.
 The  Economics of  Ground  Freezing  for Management  of
 Uncontrolled Hazardous Waste  Sites.   In:   Proceedings  of the
 1984 Hazardous  Material  Spills  Conference.   Used by
 permission  of Government Institutes  Inc.   Rockville, MD.

 From Sims,  R.C. and K. Wagner.   1983.   In-situ Treatment
 Techniques  Applicable to Large  Quantities  of Hazardous Waste
 Contaminated Soils.   In:   Proceedings  of National Conference
 on Management of  Uncontrolled Hazardous Waste Sites.   October
 31 - Nov. 2.  Used by permission  of  Hazardous Materials
 Control  Research  Institute.   Available from Hazardous
 Materials Control Research Institute,  9300 Columbia Blvd.,
 Silver Spring,  MD  20910.

 From Fitzpatrick, V.F.,  J.L.  Vcelt,  K.H. Ource,  and C.L.
 Timmerman.  1984.  In Situ Vitrification - A Potential
 Remedial Action for Hazardous Wastes.   In:   Proceedings of
 the  1984 Hazardous Material Spills Conference.   Reproduced
 with  permission of Government Institutes Inc.  The entire
 publication 1984 Hazardous Material  Spills  Conference
 Proceedings is  available  from Government Institutes, Inc.,
 966 Hungerford  Drive, #24, Rockville,  MD   20850.

 From  Conway, R.A. and R.D. Ross.  1980.  Handbook of
 Industrial  Waste Disposal.  Used by  permission of Van
 Nostrand Reinhold Company.  New York,  NY.

 From  O'Brien, R.P. and J.L. Fisher,  1983.   There  is an Answer
 to Groundwater  Contamination.   Reprinted from
Water/Engineering and Management.  Used by  permission  of
 Scranton Gillette Communications, Inc.  Des  Plaines, IL.

 From  Gulp,  R.L., G.M. Wesnar  and G.L.  Gulp.   1978.  Handbook
 of Advanced Wastewater Treatment.  2nd Ed.   Used  by
 permission  of Van Nostrand Reinhold  Co. New York,  NY.

 From  DeRenzo, D. (ed).   1975.   Unit  Operations for Treatment
of Hazardous Wastes.   Used by permission of  Noyes Data
 Corporation.  Park Ridge,  NJ.

From  Conway, R.A.  and R.D. Ross.  1980.  Handbook of
 Industrial Waste Disposal.  Used by  permission of Van
Nostrand, Reinhold Company, New York, NY.
Figure 10-6
From DeRenzo, D. (ed).  1975.  Unit Operations for Treatment
of Hazardous Wastes.  Used by permission of Noyes Data
Corporation.  Park Ridge, NJ.

                    B-5
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                            APPENDIX B (continued)
Figure 10-9
Figure 10-10
Table 10-10
Table 10-12
Figure 10-12
Table 10-14
Figure 10-13
Figure 10-14
Figure 10-15
Figure 10-16
Figure 10-17
From Gulp, R.L., G.M. Wesnar and G.L. Gulp.  1978  Handbook
of Advanced Wastewater Treatment.  2nd Ed.  Used by
permission of Van Nostrand Reinhold Co., New York, NY.
From Chemical Separations Corp.
Ridge, TN.
Ion Exchange Systems.  Oak
Hale, F.D., C. Murphy, Jr., and R. Parrat.  1983.  Page  195.
"Spent Acid and Plating Waste Surface Impoundment Closure."
Manuscripts originally printed in the Proceedings of  the
National Conference on Management of Uncontrolled Hazardous
Waste Sites - 1984 and Hazardous Wastes and Environmental
Emergencies - 1984.  Available from Hazardous Materials
Control Research Institute, 9300 Columbia Blvd., Silver
Spring, MD  20910.

From Whittaker, H.  1984.  Development of a Mobile Reverse
Osmosis Unit for Spill Clean Up.  In:  Proceedings of the
1984 Hazardous Materials Spills Conference.  Reproduced with
permission of Government Institutes, Inc.  The entire
publication 1984 Hazardous Material Spills Conference
Proceedings is available from Government  Institutes,  Inc.,
966 Hungerford Drive, #24, Rockville, MD  20850.

From Canter, L.W. and R.C. Knox.  1985.   Groundwater
Pollution Control.  Used by permission of Lewis Publishers,
Inc.  Chelsea, MI.
From O'Brien, R.P. and M.H. Stenzel.
Calgon Corp.  Pittsburgh, PA.
     Used by permission of
From Allis-Chalmers Corp.  undated.  Model SH-Rip-Flo-
Inclined vibrating screen.  Bulletin 26B11211.  Used by
permission of Allis-Chalmers Corp.  Milwaukee, WI.

From Dorr-Oliver Inc.  1983.  DSM Screens for the Process
Industries.  Bulletin No. DSM-1.  Used by permission of
Dorr-Oliver, Inc.  Stamford, CT.

From Eagle Iron Works.   1982.   Eagle Fine and Coarse Material
Washers.  General Catalog, Section C.  Used by permission of
Eagle Iron Work.  Des Moines, IW

From Eagle Iron Works.   1982.   Eagle Fine and Coarse Material
Washers.  General Catalog, Section C.  Used by permission of
Eagle Iron Work.  Des Moines, IW

From Krebs Engineers,  undated.  Krels Water Only Cyclones.
Used by permission of Krebs Engineers.  Menlo Park, CA.
                                     B-6
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                            APPENDIX B  (continued)
Figure 10-19
Figure 10-20
Figure 10-21
Figure 10-22
Figure 10-34
Figure 10-44
Figure 10-45
Figure 10-46
Figure 10-48
Figure 10-49
Figure 10-50
Figure 10-51
From Dorr-Oliver Inc.   1976.  Dorr-Oliver  Clarifiers  for
Municipal and Industrial Wastewater Treatment.  Bulletin  No.
6192-1.  Used by permission of Dorr-Oliver,  Inc.   Stamford,
CT.

From Parkson Corporation,  1984.  Lamella Gravity
Settler/Thickener, Bulletin LT-103.  Used  by  permission of
Parkson Corporation.  Fort Lauderdale, FL.

From Gulp, R.L., G.M. Wesnar and G.L. Gulp.   1978  Handbook
of Advanced Wastewater  Treatment.  2nd Ed.   Used by
permission of Van Nostrand Reinhold Co., New  York, NY.

From Gulp, R.L., G.M. Wesnar and G.L. Gulp.   1978  Handbook
of Advanced Wastewater  Treatment.  2nd Ed.  Used by
permission of Van Nostrand Reinhold Co., New  York, NY.

From DeRenzo, D. (ed).  1975.  Unit Operations  for Treatment
of Hazardous Wastes.  Used by permission of Noyes Data
Corporation.  Park Ridge, NJ.

From Vatavuk, W.M. and  R.B. Neveril.  1983.   Cost of  Flares
Chemical Engineering.   Vol. 90, No. 4.  Used  by permission of
McGraw-Hill, New York,  NY.

From Vatavuk, W.M. and  R.B. Neveril.  1983.   Cost of  Flares
Chemical Engineering.   Vol. 90, No. 4.  Used  by permission of
McGraw-Hill, New York,  NY.

From Kiang, Y and A.R.  Metry.  1982.  Hazardous Waste
Processing Technology.  Used by permission of Ann Arbor
Science Publishers, Inc.  Ann Arbor, MI.

From Kiang, Y and A.R.  Metry.  1982.  Hazardous Waste
Processing Technology.  Used by permission of Ann Arbor
Science Publishers, Inc.  Ann Arbor, MI.

From Kiang, Y and A.R.  Metry.  1982.  Hazardous Waste
Processing Technology.  Used by permission of Ann Arbor
Science Publishers, Inc.  Ann Arbor, MI.

From Rockwell International.   1980.  Molten Salt Destruction
of Hazardous Wastes.  Pub. 523-K-18-1.  Used by permission of
Rockwell International.   Canoga Park, CA.

Pradt, L.A.  1972.  (updated 1976).  Developments in Wet Air
Oxidation.  Chemical Engineering Progress.  Used by
permission of American  Institute of Chemical Engineers, New
York,  NY.
                                     B-7
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                            APPENDIX B (continued)
Figure 10-52
Figure 10-53
Figure 10-54
Figure 10-55
Table 10-19
Table 10-20
Table 10-21
Figure 11-1
From Lee, C.C., E.L. Keitz and G.A. Vogel.   1982.  Hazardous
Waste Incineration:  Current/Future Profile.  Manuscripts
originally printed in Proceedings of the National Conference
on Management of Uncontrolled Hazardous Waste Sites -  1982.
Used by permission of Hazardous Materials Control Research
Institute.  Available from Hazardous Materials Control
Research Institute, 9300 Columbia Blvd., Silver Spring, MD
20910.

From Ross, R.D.  1984.  Hazardous Waste Incineration:  More
Attractive Now than Ever Before.  Hazardous Materials  and
Waste Management Magazine.  Vol. 2, No. 5.  Used by
permission of the Hazardous Materials & Waste Management
Assoc., Kutztown, PA.

From Lee, C.C., E.L. Keitz and G.A. Vogel.   1982.  Hazardous
Waste Incineration:  Current/Future Profile.  In:
Proceedings of the National Conference on Management of
Uncontrolled Hazardous Waste Sites.  Nov. 29 - Dec. 1, 1982.
used by permission of Hazardous Materials Control Research
Institute.  Silver Spring, MD.

From Vogel, G.A. and E.J. Martin.  1983.  Equipment Sizes and
Integrated Facility Cost.  Chemical Engineering.  Vol. 90,
No. 18.  Used by permission of McGraw-Hill,  Inc.  New  York,
NY.

Adapted from Vogel, G.A. and E.J. Martin.  Estimating
Operating Costs.  Chemical Engineering.  Vol. 91, No.  1.
Used by permission of McGraw-Hill, Inc.  New York, NY.

Adapted from Vogel, G.A. and E.J. Martin.  Estimating
Operating Costs.  Chemical Engineering.  Vol. 91, No.  1.
Used by permission of McGraw-Hill, Inc.  New York, NY.

From Star, A.  1985.  Cost Estimating for Hazardous Waste
Incineration.  Pollution Engineering.  Vol.  16, No. 7.  Used
by permission of Pudvan Publishing Co., Northbrook, IL.

From Hammer, M.J.  1975.  Water and Wastewater Technology.
Used by permission on John Wiley and Sons, Inc.  New York,
NY.
Figure 11-2
From Hammer, M.J.  1975.  Water and Wastewater Technology.
Used by permission on John Wiley and Sons, Inc.  New York,
NY.
                                     B-8
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                            APPENDIX B (continued)
Figure 11-3      From Water Pollution Control Federation.  1983.  Existing
                 Sewer Evaluation and Rehabilitation.  Manual of Practice
                 FD-6.  Used by permission of Water Pollution Control
                 Federation.  Washington, DC.

Figure 11-4      From Water Pollution Control Federation.  1983.  Existing
                 Sewer Evaluation and Rehabilitation.  Manual of Practice
                 FD-6.  Used by permission of Water Pollution Control
                 Federation.  Washington, DC.

Figure 11-5      From Water Pollution Control Federation.  1983.  Existing
                 Sewer Evaluation and Rehabilitation.  Manual of Practice
                 FD-6.  Used by permission of Water Pollution Control
                 Federation.  Washington, DC.

Figure 11-6      From Water Pollution Control Federation.  1983.  Existing
                 Sewer Evaluation and Rehabilitation.  Manual of Practice
                 FD-6.  Used by permission of Water Pollution Control
                 Federation.  Washington, DC.
                                     B-9
                                  »U.S. GOVERNMENT  PRINTING OFFICE. 1986-646' I I 6/40604
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