Environmental Protection Technology Series
	
Demonstration of  The Separation

 and Disposal of

Concentrated Sediments
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                          Office of Research and Development

                          U.S. Environmental Protection Agency

                          Washington, D.C. 20460

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               RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development,
Environmental Protection Agency, have been grouped into five
series.  These five broad categories were established to
facilitate further development and application of environmental
technology.  Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface
in related fields.  The five series are:

     1.  Environmental Health Effects Research
     2.  Environmental Protection Technology
     3.  Ecological Research
     4.  Environmental Monitoring
     5.  Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series.  This series describes research performed
to develop and demonstrate instrumentation, equipment and
methodology to repair or prevent environmental degradation
from point and non-point sources of pollution.  This work
provides the new or improved technology required for the
control and treatment of pollution sources to meet environmental
quality standards.

This report has been reviewed by the Office of Research and
Development.  Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.

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                                            EPA-660/2-74-072
                                                    June  1974
           DEMONSTRATION OF THE SEPARATION
            AND DISPOSAL OF CONCENTRATED
                       SEDIMENTS
                           By

                   Michael A. Nawrocki

                 Contract No. 68-01-0743
              Program  Element  1 B2042
                   Roap/Task PEMP 03

                      Project Officer

                     John J. Mulhern
            Office of Research and Development
                 Washington, D. C. 20460
                       Prepared for
         OFFICE OF RESEARCH AND DEVELOPMENT
       U. S. ENVIRONMENTAL PROTECTION AGENCY
                WASHINGTON, D.  C.  20460
For sale by the Superintendent ol Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.45

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                                ABSTRACT

A demonstration was conducted of a system for removing and processing sedi-
ments from pond bottoms.  The removal system consisted of a MUD CAT dredge,
which is specifically designed to dredge without imparting substantial turbid-
ity to the water column. The 500 gpm processing system consisted of, in order
of flow, a pair of elevated clarifier bins arranged in series, a bank of hydro-
cyclones, a cartridge filter unit, and a Uni-FIow bag-type fabric filter consist-
ing of 720 one-inch diameter polypropylene hoses.

The MUD CAT dredge proved efficient in removing the pond sediments and
did not produce a substantial amount of resuspension of the sediments. An
average final effluent quality of 445 mg/l of suspended solids was achieved
by the processing  system, with a reported range of from 47 to 1770 mg/l.  The
most effective components of the system in removing suspended sediment were
the clarifier bins and the Uni-FIow filter.

After the field demonstration, further experiments were conducted on larger,
five-inch diameter Uni-FIow hoses.  Different materials,  methods of screen-
ing, and lengths were tested in order to optimize the operating parameters of
the hoses.  It was determined that eight-foot long,  polypropylene hoses with
wire caging on  both the inside and outside of the hose were more suited for
further development than the other configurations tested.  This hose yielded
comparable effluent qualities and throughflow rates and required less hard-
ware than the other hoses.

This report was submitted in fulfillment of Contract Number 68-01-0743 by
Hittman Associates, Inc. under the sponsorship of the Environmental Protec-
tion Agency.  Work was completed as of November 30,  1973.
                                     ii

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                               CONTENTS

                                                          PACE

Abstract	     i i

Table of Contents	     i i i

List of Figures	     iv

List of Tables	     v

Acknowledgments	     vi

SECTIONS

    I          Conclusions	      1

    II         Recommendations	      3

    III        Introduction	      4

    IV        Removal and Processing Systems	      6

    V         Field Demonstration	     17

    VI        Discussion of Field Demonstration	     29

    VII        Additional Tests-Large Diameter Fabric
                 Fi Iter  Hoses	     43

    VI11       References	     60

    APPENDICES	     61
                                   in

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                               FIGURES

NO.                                                         PAGE

1         MUD CAT Dredge	       6
2         Close-up of MUD CAT Auger	       7
3         Initial Solids Removal Phase:  Elevated Bins	       10
4         Secondary Separation:  Hydrocyclones	       12
5         Final Filtration: Cartridge Filter Unit	       13
6         Final Filtration: Uni-Flow Filter	       14
7         Schematic of Processing and Sludge Disposal
            System	       16
8         Solids Balance for Processing System 	       26
9         Sediment Accumulated in First Bin After Two
            Hours of Dredging	       33
10        Large Diameter Fabric Filter Hose Test Apparatus .      45
11        Flow vs. Time (Eight-Foot Hose)	       52
12        Effluent Concentration vs. Time (Eight-Foot
            Hose)	       53
                                    IV

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                                  TABLES
NO.                                                            PAGE

1           Theoretical Settling Velocity of Particles in
              Water at 10° C		        10

2           Demonstration Pond Characteristics	        17

3           Physical Characteristics of Composite Sediment
              in Pond Before Dredging  	        19

4           Summary of System Component Effluent Concen-
              trations  (mg/l)  	        23

5           Summary of Sludge (Backflush) Concentrations
              (mg/l)	        23

6           Removal Efficiencies of System Units (All
              Units On  Line) 	        24

7           Results of Bins to Uni-Flow  Filter Run	        27

8           Destination of Dredged Sediment	        29

9           Capital Costs of the Portable Sediment Pro-
              cessing System 	        40

10          Six-Week Operating and Maintenance Costs of
              the Portable Sediment Processing System
              (Excluding  Trucking)  	       41

11          Summary of First Phase Five-Inch Uni-Flow
              Hose Tests  	        48

12          Summary of Results of Second Phase Poly-
              propylene Testing  	        51

13          Summary of Results of Second Phase Poly-
              propylene Testing for Influent Concentrations
              near 10,000 mg/l  	        51

14          Performance History of Uni-Flow Fabric Filters / •       55

15          Filtration Rate Ranking of Polypropylene Fabric
              Fi Iters 	        57

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                           ACKNOWLEDGMENTS

The support and technical guidance received from Mr. John J. Mulhern,
serving as Project Officer for the Environmental Protection Agency, is greatly
appreciated.  His guidance, timely suggestions, and technical expertise in
the area of filter bag technology were especially helpful.

The field demonstration of the dredging and processing of the dredge spoil
was done in cooperation with the Prince George's County, Maryland, Depart-
ment of Public Works.  They allowed unrestricted use of their sediment pond
for dredging operations,  and the surrounding land for the processing.  They
also provided access roads and grading at the processing site, constructed
the necessary disposal basins, and provided dump trucks for hauling of the
separated solids.
                                     VI

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                               SECTION I
                             CONCLUSIONS

The  MUD CAT  dredge proved very  efficient in removing the deposited
sediments from the pond  bottom and in  preventing the resuspension of
the sediments during the dredging  operations.  Overall, it lived up to
its design criteria of being an efficient  means of removing sediment from
ponds  and lakes  up to  10.5 feet in  depth.

Overall, the portable sediment processing system, consisting of two
elevated clarifier bins, hydrocyclones,  a cartridge filter unit, and a
Uni-Flow bag-type fabric filter,  proved efficient  in removing suspended
sediment from a dredged slurry.

The  most efficient components of the system for sediment  removal were
the elevated bins  (initial solids removal phase)  and the Uni-Flow filter.
They were both very effective in removing suspended solids  from the
dredged slurry during the  field demonstration.

The  hydrocyclones were  not as efficient in removing  suspended solids
from the dredged  slurry  as originally anticipated.  Use of a closed
underflow header  with  silt collection pots  and automatic solids unload-
ing on the hydrocyclones is probably not  justified in a portable  sedi-
ment processing system.  In addition,  the  use of hydrocyclones  for
dredged spoil processing should be  limited to removing sand-size,
i.e.,  74 microns,  or larger particles.

The  usefulness of the  cartridge filter unit in the processing system was
marginal.  Operating and maintenance  restrictions would probably  pre-
clude the widespread utilization of such units for processing dredged

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slurry unless the suspended  solids concentration  of the slurry could
first be reduced  to near the design  level of the units.

Overall,  the  removal system utilized proved to be a  labor-intensive
operation.

This program demonstrated that sediment basins  can be cleaned without
the availability of adjacent sediment deposition sites  and that  a high
quality return water can  be produced  through use of a portable sediment
processing system.

Five-inch diameter polypropylene hoses  tested on a prototype test stand
performed better than the  one-inch hoses utilized on the Uni-Flow  filter
during the field  demonstration.

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                               SECTION II
                          RECOMMENDATIONS

It is recommended that the MUD CAT dredge or its equivalent be utilized for
dredging of unconsolidated sediments from water bodies within its operational
capabilities, since it produces a minimum of resuspension of the sediments
into the water column.

Systems  similar to the portable sediment processing system demonstrated
should be considered for areas where dredging is required and adequate
space is  not available for conventional settling basins.  The sizing and selec-
tion of the individual components should be done on a site by  site  basis.  The
clarifier bins, hydrocyclones, and Uni-Flow filter are all applicable to the
processing of dredged  sediments but must be sized with the physical charac-
teristics of the dredged sediment and the solids loading rate expected in mind.
Utilization of a cartridge-type water filter for processing of dredged slurry is
not recommended due to the operational  difficulties encountered while using
it on influents with high suspended solids contents.

It is recommended that five-inch diameter hoses be utilized in any future
Uni-Flow filter applications.  It is also recommended that the Uni-Flow filter,
in the form of an adapted air bag house, be utilized  for processing wastes
where the removal of suspended solids is a primary consideration.  Further,
it is recommended that  further tests be performed on the five-inch diamater
Uni-Flow hoses for their applicability to the filtering of other types of wastes
and pollutants.

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                              SECTION III
                             INTRODUCTION

 In recent years, more and more developments are being built around natural
 and man-made lakes. These lakes serve as recreational and aesthetic focal
 points for the surrounding communities.  Unfortunately, these lakes often be-
 come choked with sediment rather early in their lifetime due to soil erosion
 resulting from construction activity in the watershed.  In order to restore these
 lakes to their original condition, some type of cleaning operation is necessary.
 In many cases, however, little premium land is available near the lake to con-
 duct the necessary conventional dredging operations or for the standard sett-
 ling ponds or diked disposal areas.

 In numerous other cases, the disposal of dredged spoil and the return of the
 effluent to the water body has had severe restrictions placed upon it.  The
 disposal of dredged material from small boat harbors onto the surrounding
 wetlands is  no longer allowed in most cases; the disposal of dredge spoil on
 floodplains is being severely limited; and the effluents from dredging opera-
 tions are receiving increased attention as water pollutants. Another problem
 associated with most conventional dredging operations  is the turbidity im-
 parted to the water body by the dredging operations themselves.

 Consequently, Hittman Associates, Inc., under contract to the Environmental
 Protection Agency, conducted a demonstration of the separation and disposal
of concentrated sediments from the dredging operations on a small lake.  The
purpose of the demonstration project was twofold.  One, was to demonstrate
a technique for relatively small maintenance dredging operations which would
have minimal adverse effects on the surrounding water body. The second
purpose of the program was to demonstrate a portable sediment processing

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system which could be set up to process the dredge effluent in a relatively
small area, remove the majority of the solids, return clean water to the pond,
and then be dismantled and moved after the dredging operation is complete.

The  dredge used was a MUD CAT dredge manufactured by National Car Ren-
tal Systems, Inc.  It is specially designed for use on small lakes, and to im-
part minimum turbidity to the water while dredging. It can discharge approx-
imately 1500 gallons per minute (gpm) of slurry with a solids concentration
of 10 to 30 percent.

The  portable sediment processing system consisted of a pair of elevated
settling bins, a bank of hydrocyclones, a standard cartridge-type water
filter unit, and a bag-type filter known as a Uni-Flow.  Basically, the Uni-
Flow filter consists of a number of hanging hoses.  The dirty water is pumped
into  the inside of the hoses and is allowed to filter through them.  Periodically,
the collected sludge is flushed from the inside of the hoses.  The design of
the Uni-Flow filter was based on experiments performed on a full-scale test
stand.  The total processing system was tested in a number of different arrange-
ments during the course of dredging operations.

Additional experiments were also performed on the Uni-Flow bag-type filter.
These tests were done on full-scale test stand after experiments with the
total processing system in the field were complete.  The purpose of these
additional experiments was to  refine the technology of the Uni-Flow filter to
a point where additional prototype units could be built for other water and
waste filtering applications.

This report constitutes the final report on the entire project.  It includes the
system design, the results of the  field trials of the dredged slurry processing
system, and the results of the additional testing of the Uni-Flow filter hoses
on the test stand.

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                             SECTION IV
                 REMOVAL AND PROCESSING SYSTEMS

REMOVAL SYSTEM

The system utilized for removing sediment from the demonstration pond bot-
tom consisted of a 30-foot 2-inch long MUD CAT dredge manufactured by
National Car Rental System, Inc., MUD CAT Division.  The dredge moves in
straight-line directions by  winching itself along a taut,  fixed cable.  Figure 1
is an overall view of the MUD CAT dredge.

Bottom sediment removal equipment on the dredge consists of an eight-foot
long,  horizontally-opposed, adjustable depth, power-driven auger and a pump
which is rated at approximately 1500 gallons per minute with a 10-30 percent
                 FIGURE 1.  MUD CAT Dredge

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solids concentration of the slurry.  A retractable mud shield over the auger
minimizes mixing of the disturbed bottom deposits with the lake water.  Figure
2 is a close-up view of the auger on the MUD CAT dredge.  The dredge also
comes equipped with a rock box into which objects greater than eight inches
in diameter (the diameter of the discharge line)  are automatically discarded
before the dredge spoil is pumped into the discharge line.

PROCESSING SYSTEM UNITS

The development of a portable sediment separation system centered around
the use of a hydrocyclone initial stage followed by the Uni-Flow filter.  Other
alternative or additional devices were also evaluated for possible inclusion
in the processing system based on the equipment's degree of portability, cost,
expected performance, and the physical  characteristics of the dredge spoil.
            FIGURE 2.  Close-up of MUD CAT Auger

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Under normal conditions, the discharge from the MUD CAT dredge can be
expected to contain between 10 and 30 percent solids by weight.  This rela-
tively high concentration of solids is an advantage in that  less dredge spoil
needs to be processed to remove a given amount of sediment.   However, at
the expected flow rates,  such solids  loadings exceed the design capacity of
standard hydrocyclone units.  In addition, some larger diameter gravel and
rock  can be expected to be pumped by the MUD CAT.  The larger particles
would be too large to be  processed by the hydrocyclones.  Consequently, an
initial solids removal phase was  deemed to be required in  order to remove the
larger particles and to generally reduce the overall suspended solids loading
of the dredged slurry before processing by the hydrocyclones.

In order to achieve as clean a return water to the pond as possible, a final
filtration step was added to the portable sediment processing  system.  Two
different filters were installed and tested as part of this final  filtration step.
One was the  Uni-Flow bag-type filter concept.  The other was a commercially
available cartridge-type water filter.

Basically,  therefore, the portable sediment separation system consisted of
three general steps:
       1.     Initial  solids removal
       2.     Secondary separation (hydrocyclones)
       3.     Final filtration (cartridge filter unit and/or Uni-Flow filter)

In order to economically  demonstrate a  fully portable system, the total flow
from the dredge was split after the initial solids removal phase.  Thus,  the
fully portable system was designed to process a nominal 500 gpm.  The re-
maining flow  of approximately 1000 gpm was sent to a temporary earthen
holding/settling basin.

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Initial Solids Removal

The alternatives considered for the initial solids removal phase were narrowed
down to either provide a type of portable settling tank or utilize one of the
various coarse screening techniques available.  The first alternative, that is,
the settling tank, in the form of elevated bins of the type used for concrete
batch plants, was found to be the most attractive alternative.  Advantages of
the elevated bins over the various screening techniques include:

      (1)   Settled solids  can be loaded directly onto trucks by gravity flow.
      (2)   The bins are self-cleaning with steep-sloped sides.
      (3)   The elevated bins provide head for the pump which feeds the
            secondary separation phase (hydrocyclones) .
      (4)   Ease of incorporation of a flow splitter device which would
            enable gravity flow to the holding basin.
      (5)   Elevated bins  are not subject to clogging as some screens  are.
      (6)   Elevated bins  are less costly  and  remove a greater portion  of
            the suspended solids at the given flow rate of approximately
            1500 gpm.

Two elevated bins,  each  with an initial capacity of 36 cubic yards were  in-
stalled in series as  the initial solids  removal phase.  The discharge from the
dredge  was pumped directly to the first bin where settling of suspended
solids occured.  The slurry was then allowed  to overflow  into the second
bin,  where additional settling occured. From the second bin, the flow was
split to either the temporary  holding basin or to the feed pump for the hydro-
cyclones.  Figure 3 shows  the elevated bins used for the field demonstration.

Each of the elevated bins selected for testing in the portable sediment separ-
ation system provided about  144 square feet of surface area for settling. At
the expected 1500 gpm flow rate, a theoretical upflow velocity of approximately

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        FIGURE 3.  Initial Solids Removal Phase:  Elevated Bins

0.023 ft/sec is  produced. Based on the theoretical settling velocities for vj
ious size particles presented in Table 1, all particles down to approximatel
100 microns in  size could be expected to be settled-out in the initial solids
removal step.
               Table 1.  THEORETICAL SETTLING VELOCITY OF
                       PARTICLES IN WATER AT 50° F
      Diameter of Particles
         (microns)
Settling Velocity
 (ft/sec)
            1000

             500

             200

             150

             100

              50
        0.328
        0.174

        0.069

        0.049

       0.026

       0.010
                                     10

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Secondary Separation

A bank of hydrocyclone cones comprised the secondary separation step of
this portable sediment handling system.  Hydrocyclones are excellent devices
for use in portable sediment processing installations.  Their advantages over
conventional water treatment alternatives in these situations include:
      (1)   Compact units make them easily portable.
      (2)   Automatic operation.
      (3)   No backwash or filter cleaning cycle is required.
      (4)   Generally maintenance-free since there are no moving
            parts.
      (5)   Removal of particles in the desired size range can be simply
            accomplished through the selection of the proper cone size.

The hydrocyclones utilized for this demonstration project were manufactured
by DEMCO Incorporated and consisted of six four-inch, style H cones with
abrasion-resistant urethane liners, and equipped with three-gallon silt pots,
a closed  underflow header, and automatic solids unloading.  Figure 4 shows
the hydrocyclone unit as installed in the sediment processing system.

Final  Filtration

Final  filtration of the dredged slurry was required so that a high quality
effluent could be  returned to the pond.  Two separate filtering schemes were
utilized for this step:
      (1)   A commercially available polishing filter
      (2)   A prototype of the Uni-Flow wet bag-house type filter

The commercially-available filter selected for the field trials was of the
cartridge filter type  and was manufactured by Crall Products, Inc.  and
                                     11

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          FIGURE 4.  Secondary Separation:  Hydrocyclones
assembled by DEMCO Incorporated.  The unit consisted of four model 16-17-51
filters, each of which contained 51 permanent sand cartridges with filter
openings rated at 25 microns.  An on-line automatic backflush cycle was in-
stalled so that one filter unit could be backflushing while the other three re-
mained on-line. Figure 5 shows this cartridge filter unit. Selection of this
type of polishing filter was based on the following:
      (1)    Its compatibility with the hydrocyclone unit over its entire range
            of working pressures.   Therefore,  no booster pumps were required.
      (2)    Relative ease of maintenance and ability to change filter cartridges.
      (3)    Range of flow rates available for cartridge elements with various
            rated  openings.
      (4)    Small  size in that only  87.5 square  feet were required for a fully
            automated unit which could handle the expected 500 gpm of flow.
                                    12

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          FIGURE 5.  Final Filtration:  Cartridge Filter Unit
Previous experiments with the Uni-Flow filter indicated that such filters
showed promise for use as a final polishing filter for suspended sediment
slurries, in that high quality effluent water could be expected. Basically,
the Uni-Flow filter is  a system of hollow fabric "soaker" hoses that present
a more or less solid, impermeable barrier to suspended material. The dredged
slurry is pumped into the center of the hoses, the suspending liquid permeates
through the hoses and is collected in a filtrate collector and is piped away.
The loose sludge within each hose is periodically discharged into a sludge
collector and is removed from the filter  unit.

Further experiments were conducted under this  program in order to arrive
at design criteria for a prototype unit which would be capable of processing
the expected 500 gpm of flow.  Relying on the  previous basic data, one-inch
diameter,  10 to 20-foot long hoses of both cotton  and polypropylene  fabrics
was tested on a small, three-hose test stand.
                                    13

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The final design criteria arrived at through these tests produced a unit which
contained 720 one-inch diameter,  10-foot long, woven polypropylene hoses.
The hoses were arranged in six banks of 120 hoses each. This enabled the
shutting-down of one bank for hose maintenance or replacement while the
other five banks could be kept on-line.  The slurry was pumped into a top
header which distributed the influent to each bank of hoses.  The  filtrate
from the hoses was collected in a bottom tray and allowed to flow by gravity
back to the pond. Every 5 1/2 minutes, the sludge within the hoses was
drained for 30 seconds  into a collection trough and allowed to flow by gravity
into a sludge disposal basin.  Figure 6  shows this prototype Uni-Flow filter.
        FIGURE 6.  Final Filtration:  Uni-Flow Filter

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OVERALL SYSTEM DESCRIPTION

Figure 7 is a schematic diagram of the overall processing and sludge disposal
system.  Bypass lines were constructed within the system so that selected com
ponents of the system could be bypassed in order to test the operating aspects
of the system with the different units on-line.  During the field demonstration,
a number of different system configurations were tested.  These were:

      (1)   Entire system
      (2)   Bins, hydrocyclones, and cartridge filter unit
      (3)   Bins, hydrocyclones, and Uni-Flow filter
      (4)   Bins to Uni-Flow filter

Samples of the dredged slurry were taken periodically before and after each
piece of equipment, and of the backflushes or sludges from each piece of
equipment.  With this sampling program, many other system configurations
could be tested besides the four listed above.  For example, samples from
the process stream immediately after the elevated bins would define how
efficiently a processing system consisting of only the bins would be in re-
moving suspended sediment.  Similar analyses could be made at each point
in the processing stream.

The portability of the system was evidenced by its ability to be transported
entirely on two standard, flat-bed, semitrailer trucks.  Auxiliary equipment
such as  valves, air compressor, miscellaneous piping, etc.  all fit on a stan-
dard pick-up truck.
                                   15

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                                                      Temporary Holding/
                                                        Settling Basin
MUD CAT discharge
 approx. 1500 pgm
Initial Separation
Two 36-yard
 Elevated Bins
                                                 approx.
500 gpm
            Secondary Separation
               Hydrocyclones
Final Filtration
Cartridge Filter
     Unit
                                                                            Final Filtration
                                                                                                        Uni-Flow Filter
                                                                 foackflush
                                                                                         backflush
                                trucking
                                                                             backflush
                                                                                  Return Water
                                                                                  to pond
                        Bin Solids
                        Disposal Area
                                                                   Sludge Disposal

                                                                   Area
                            Figure 7.   Schematic of  Processing and Sludge Disposal  System

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                              SECTION V
                        FIELD DEMONSTRATION

TEST SITE

The  site selected for the field demonstration of the removal and  processing
system was  located in Prince George's  County, Maryland, at  what is known
as the Bowie Airpark Site.  This  site contains a pond which  was designed
and  built as  a  sediment retention  basin to control sediment produced by
airpark construction.  Table 2 presents the pertinent characteristics of
this  pond.

          Table 2.   DEMONSTRATION POND CHARACTERISTICS

Surface Area                        1.7 acres
Maximum depth                     9.0 feet
Present Condition                    99 percent filled with sediment
Age                                 2 years
Estimated Capacity                   14,000 cubic yards

Since the maximum water depth of the pond before dredging  began  was
less  than the minimum depth required to float the MUD CAT dredge, that
is, approximately 21  inches, it was necessary to  raise both the  normal
and  emergency spillway elevations in order to acquire enough freeboard to
float  the MUD CAT.   A small spring  fed the pond and helped to provide
adequate water for  dredging.

The  processing system was set-up on a 50-foot high  knoll, approximately
600 feet  from the edge of the pond.  From this site,  the  overflow  (split
                                  17

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 flow)  from the bins  and the backwash sludges from  the hydrocyclones,
 cartridge filter unit, and Uni-Flow filter could flow  by gravity  to, respec-
 tively, the temporary holding/settling basin and the sludge disposal  basin.
 Both these basins were formed by earthern  dikes.   The clean water  efflu-
 ent from the processing system could also  return to the pond by gravity
                                                       tv
 flow.   After  decanting the excess water, the solids  from  the elevated bins were
 emptied directly  into dump trucks and were trucked to a disposal area in
 another part of the  Bowie  Airpark Site.

 BASELINE SURVEYS

 Approximately two months before dredging and processing operations be-
 gan, a number of water quality  and  sediment  samples  were taken in  the
 demonstration pond  in order to establish the natural pond conditions  and
 to  aid  in the final design of the  equipment for the sediment processing
 system.  The pond  water was  sampled at a number  of points throughout
 the pond.  These samples were  analyzed for a number of the standard
 water quality indicators.   The results of these analyses are given in
 Table A-1 in Appendix A.

 Six core  samples, up to two feet in depth, of the  undisturbed pond bottom
 were acquired.   These sediment samples were analyzed for their grain
 size distribution  and specific gravity.  These  analyses were useful in
 providing final specifications and design  criteria for the hydrocyclone
 and cartridge filter  units  in the  processing system, even  though  full-
 depth  core samples of the pond sediments could not be obtained.   Table
 3 shows the  composite grain size distribution of the undistrubed pond
 sediments.  As  can be seen from the  table,  the large majority of the
sediment is finer  than 100 microns.  This affected the design of  the
equipment for the sediment processing system in the  following ways:
                                   18

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         Table 3.  PHYSICAL CHARACTERISTICS OF COMPOSITE
         	SEDIMENT IN POND BEFORE DREDGING	

Grain Diameter  (microns)                     Percent Finer

250                                         99

150                                         95

100                                         91

 40                                         12

  8                                          7

  3                                          6

  1                                          2

Average Specific Gravity = 2.3

In-Place Moisture Content = 28.8 to 50.3 percent
                                  19

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    (1)    The automatic  dump  cycle on the hydrocyclones was shortened
to  provide the capability to unload accumulated solids at intervals less
than 15 minutes  apart.

    (2)    Automatic  backflushing of the  cartridge filters was similarly
specified at less than 10 minute intervals between  cycles.

During  the initial  dredging operations, a number of samples were taken
of both  the undisturbed pond water and of the MUD CAT  discharge.
These  samples were composited and subjected  to a  more rigorous  water
quality  analysis.   A comparison between  the water  quality of the pond
water and that of  the dredged  slurry  could thus be obtained.  This
comparison gives  an indication of constituents  which might be present  in
the pond  sediments but which  are  not present  in significant  quantities  in
the pond  water itself.  Tables  A-2 and A-3 in Appendix A present the
complete results of these baseline water quality tests.

RESUSPENSION OF BOTTOM  SEDIMENT DURING DREDGING

A  sampling and  analysis program was initiated to determine  the amount of
sediment which was  resuspended into the pond water as a result of the
dredging  operations.   Samples  were taken around  the periphery of the
dredge  at various  distances  from the dredge and at various  depths.  These
samples were analyzed for their  suspended solids  concentrations.

Generally, the MUD  CAT dredges more efficiently during a  backward cut
than during a forward cut.  This is  true from both a solids removal and
a resuspension of  sediment aspect.  During a  backward cut, the mud
shield  is lowered  over the auger  (see Figure 2), and the bottom sediment
is  dragged into the auger.   This allows a deeper cut along with  less
                                   20

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sediment being imparted to  the water.  During a  forward cut, the dredge
proceeds with the mud  shield raised.   The auger alone then acts to convey
the solids into the pump intake  line.  This not only imparts  a greater
amount of turbidity to the surrounding water,  but also is a less efficient
method of picking-up the bottom  sediment.

Consequently, the sampling and analysis  program concentrated on deter-
mining the resuspension during the worst case, that is,  during  the  forward
cut mode of operation.  Appendix B contains the detailed data from this
sampling and  analysis program.

In general,  the suspended sediment plume imparted to  the  surrounding
water during  dredging  is confined to within 20 feet of  the  dredge.   The
maximum suspended solids  concentration  reported within  the  plume was
1260 mg/l.  Also, the major part  of this  plume is confined to the area
directly in front  of the dredge.   In addition,  some  turbidity  is occasion-
ally  imparted  to the water behind the  dredge.   This is not a direct  result
of the dredging operations, but due to the fact that the fresh water  system
intake is located  at the rear of the dredge.  The  system  is used to flush
the main pump bearings and the auger bearings.   The fresh water intake
will  sometimes stir up the bottom  sediments if  the pond is  relatively shallow,
thus imparting a  small  plume of suspended sediment to the water behind
the dredge.

PROCESSING SYSTEM EFFICIENCY
Suspended Solids Removal

Slurry from the dredging operations was  pumped through the portable
processing system described in  Section IV for  a total of  seven weeks.
During this time, the system was  tested  in a number of  different config-
                                   21

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 urations,  including bypassing  of the cartridge filter units, and processing
 directly from the elevated bins to the Uni-Flow  filter.

 Appendix  C contains  the  detailed  data on the  water quality monitoring
 program for the processing system.  Table 4  is a  summary of the sus-
 pended  solids concentrations in the effluents of the components of the
 processing system when the full system  was in operation.  Similarly,
 Table 5 is a  summary of the concentrations of suspended  solids  in the
 sludges or backflushes of the  system components.  This table gives  an
 indication  of  the solids concentration in  the sludge which  can be expected
 or achieved from the system during  fully automatic operation.  Basically,
 the sludge from the hydrocyclones ranged from 2  to 29 percent solids,
 with an average of 10 percent; the backflush  from the cartridge filters
 ranged  from  2  to 28 percent solids with  an average of 8 percent; and the
 sludge from the Uni-Flow filter ranged from 5 to  19 percent solids, with
 an average of  11 percent.

 Table 6 gives an indication of the average efficiency of the system as a
 whole, and of the individual components, in removing suspended solids
 from the dredged slurry.  This table indicates that the largest amount of
 solids are removed by two components,   the clarifier bins  and the Uni-
 Flow fabric filter.  This  data confirms the field observations.

 A solids balance for the entire processing  system was computed utilizing
 the average suspended solids concentrations shown in Table  6, a MUD CAT
 pumping rate of 2000 gallons per minute, which  was  the average during the
 field demonstration, the reported average specific gravity of the pond sedi-
 ments of 2.3, and the average total system  flow rate during the field demon-
 stration of  220 gallons per minute.  This solids balance was computed in
order to  give an indication of the amount of solids generated and  processed
                                   22

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Table 4.  SUMMARY OF SYSTEM COMPONENT EFFLUENT CONCENTRATIONS
                            (mg/l)
Component
MUD CAT Discharge
Elevated Bins Effluent
Hydrocyclones Effluent
Cartridge Filters Effluent
Uni-Flow Filter Effluent
(Return Water to Pond)
Max
261,
254,
179,
105,
1,
. Run
000
000
600
400
770
Min. Run
107,000
55,800
31,400
22,700
100
Run Aver.
170,300
131,200
88,300
57,200
445
    Table 5.  SUMMARY OF SLUDGE  (Backflush) CONCENTRATIONS

Component
Hydrocyclones
Cartridge Filters
Uni-Flow Filter

Max
293,
284,
191,
(mg/l)
. Run
000
600
600

Min. Run
22,000
22,000
51,000

Run Aver.
103,500
82,800
114,300
                             23

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                    Table 6.  REMOVAL  EFFICIENCIES OF SYSTEM UNITS
                                  (All Units On Line)
Component Aver. Suspended Solids Percent of Inflow Percent Removed Percent Removed
Concentration (mq/l) Solids Remaininq Through System per Component
MUD CAT Discharge
Bins Effluent
Hydrocyclones Effluent
Cartridge Filters Effluent
Uni-Flow Effluent
170,300
131,200
88,300
57,200
445
100
77.0 33.0
51.8 48.2
33.6 66.4
0.3 97.7
-
33.0
15.2
18.2
31.3
(Return Water to Pond)

-------
by each component of the system when it is in a fully automatic mode of oper-
ation.  Figure 8 presents this system solids balance.

The  Uni-Flow filter  was observed to have a very  high  efficiency  in re-
moving suspended solids from the dredged slurry, even when the cartridge
filter unit as an  initial final filtration step  was bypassed.   Consequently,
an experiment was conducted during the field trials in which both the
hydrocyclones and the cartridge filter  units were  bypassed, that  is, the
dredged slurry was pumped directly from the effluent of elevated clarifier
bins to the Uni-Flow filter.  Table  7 summarizes  the results of this run.

The  run began with clean bins and clean but used hoses on the Uni-Flow
filter.   Five  of the six banks of hoses  were in operation.   The system
was  run at the maximum Uni-Flow pressure (and  consequently the maxi-
mum flow rate) which it  could be operated at without  causing excessive
bowing of the hoses and  their consequent bursting.  As can be seen from
Table  7, the Uni-Flow  filter still  had a high efficiency  of removal of sus-
pended solids in  this  configuration.  However, due to the high solids
concentrations in the influent, the hoses soon became blocked with  sedi-
ment,  and the flow  rate through the system decreased rapidly.   The
automatic backflush  cycle of 5 1/2 minutes  between flushes  with  a one-
half  minute duration flush was not sufficient to prevent the hoses from
becoming blocked with accumulated sediment.   Consequently, the run had
to be terminated  after 90 minutes  when  the hoses  became completely
blocked with sediment and  the system throughflow decreased to near zero.
                                   25

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   MUD CAT
   discharge
  3152 Ib/min.
K)
                            2109  Ib/min.
Initial Separation
 Two 36-yard
 Elevated Bins
                     trucking
                     782
         b/min.
                  Bin  Solids

                  Disposal Area
                                    261 Ib/min.
                                    Temporary
                                  Holding/Settling
                                       Basin
Secondary Separation

   Hydrocyclones
                                            back flush
                                            90 Ib/min.
                        171
                        Ib/min.
Final Filtration
Cartridge Filter
     Unit
 109
Ib/min.
                                        backflush
                                        62 Ib/min.
        Final Filtration
                                                        Uni-Flow Filt :r
                          backflush
                          108 Ib/min.
                                                                             Sludge Disposal

                                                                                  Area
                                                                                                     Roturn Water
                                                                                                     to pond
                                                                                                      I Ib/mln.
                                                                                              260 Ib/min. total
                            FIGURE  8.   Solids  Balance for Processing System

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Table 7.  RESULTS OF BINS TO UNI-FLOW FILTER RUN
Time (min.) Suspended Solids Concentration (mg/l)


15

30
45

60
75

90
MUD CAT
Discharge

158, 200>
/

96, 20o}
*


145,90ol
/
Bins
Effluent

135,900>
/

70,10ol
/

84, 50o}
/
Uni-Flow
Effluent

208\
J
\
127}


424}

System Flow
(gpm)

250

120
70

60
50

30
Uni-Flow
Pressure (psi)

8

10
12

12
10

11

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 Other Water Quality Parameters

 Seven additional water quality constituent parameters were intermittently
 measured during the testing program.  The parameters measured were:
 orthophosphate (PO   ), nitrate and nitrite nitrogen (NO   + NO   )
 iron  (Fe  ), sulfate  (SO=), hydrogen ion  concentration  (pH) and turbidity
 measured in Jackson Turbidity Units (JTU) .  The phosphate, nitrate, nitrite,
 iron, and sulfate chemical analyses were performed with a Hach Chemical
 Company portable water quality laboratory kit. Turbidity and pH measure-
 ments were performed with a Hach turbidimeter and a Fisher Accument pH
 meter respectively.  Summary data results for five days of test operations
 are presented in Appendix C, Table C-2.

 Because the parameters measured were, with the exception of turbidity,
 essentially completely dissolved upon entering the settling bins (sample
 point # 5), it was generally expected that  the physical sediment separation
 unit processes being evaluated would have little or no effect on their con-
 centration.  Speculation was made that interactions between  the various ions
 and suspended sediment particles might result in some ion removal, partic-
 ularly with the Uni-Flow filter unit.

 Inspection of the test data results indicates that no substantial ion removals
occurred.  The accuracy of the test results are such that the data are in-
conclusive  as to whether minor amounts of ion removal were effected.
                                   28

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                              SECTION VI

                 DISCUSSION OF FIELD DEMONSTRATION

REMOVAL SYSTEM

During the field demonstration period, approximately 10,000 cubic yards of
material was removed from the pond.  Of this total, 3000 cubic yards was
pumped into the bins for processing, and the remaining 7000 cubic yards
was disposed of in a conventional settling basin. Table 8 shows the destin-
ations of the various quantities of material from thetotal sediment removed
from the pond.

             Table 8.  DESTINATION OF DREDGED SEDIMENT
Destination                                  Quantity (cu.yd.)
Settled in Bins                                  750
Processed Through Remainder of System          250
          Total Removed by System             1,000
Bins Overflow to Holding Basin                  2,000
          Total Pumped to Head End of System    3,000
Pumped to Conventional Settling Basin           7,000
          Total Removed from Pond           10,000

The MUD CAT dredge proved  very efficient in removing the deposited sedi-
ments from the pond bottom and in preventing the  resuspension of the sedi-
ments during the dredging operations.  Minor perturbations to the smooth
dredging operation were the result of:

    (1)    Clogging of the pump or fouling of the auger by  large debris and
objects such as tree stumps, logs, large rocks,  or lengths  of barbed wire.
                                       29

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No damage is done to the dredge due to this blockage or fouling, and dredg-
ing can be continued as soon as the pump and auger are shut down and the
debris is removed.
    (2)    Bars of sediment which protrude above the water level. Dredging
operations are slowed by cuts which must be made above water level.  In
this case, the auger and intake must be raised and the sediment must be
dragged back into the pond by the mud shield.  This operation must be
repeated until adequate draft  (approximately 18 inches) is available for
passage of the MUD CAT.   Naturally, this operation takes longer than a
normal dredging operation, but is well within the capabilities of the MUD
CAT.
     (3)    The need for quite a number of positioning moves of the dredge
in order to dress-up the banks of the pond.  Since movement of the MUD
CAT is limited to a straight line along a taut, fixed cable, this cable must
be  moved a greater number of times per cubic yard of sediment dredged
when short cuts are being  made in order to dress-up the pond banks.

Overall,  the MUD CAT dredge lived up to its design criteria of being an
efficient means  of removing sediment from ponds and lakes up to 10.5 feet
in depth.  It or an equivalent dredge's application  to such  lake cleaning
operations is thus recommended.  Some additional advantages of the MUD
CAT in this connection include:

    (1)    The dredged slurry can be pumped to a  remote site for disposal,
thus eliminating the near shore mess that is  usually associated with conven-
tional dragline operations. The engine and pump on the MUD CAT permit
the slurry to be moved up to 3000 feet from the lake without the use of a
booster pump.
                                   30

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      (2)   Since the MUD CAT was not built for dredging through undis-
turbed ground, there is probably little danger of inadvertently puncturing
the natural pond or lake bottom and causing leakage.
      (3)   The MUD CAT can usually be unloaded directly  into the lake or
pond from a standard-size, tilt-bed trailer.

PROCESSING SYSTEM

Overall,  the processing system proved effective in removing the large
majority  of suspended sediment from the dredged slurry.  The average
return water quality to the pond contained 445 mg/l of suspended solids.
Each component's individual contribution to the efficiency of the total sys-
tem varied, however.  The operational aspects of each component are dis-
cussed in the succeeding paragraphs.

Elevated  Bins
The elevated clarifier bins performed very efficiently as an initial solids
removal phase in the sediment processing system.  Their actual efficiency,
in fact, was discovered to be better than their expected efficiency as predicted
by ideal settling theory.  Tables C-3 through C-5 in Appendix C show the
grain size distributions of composite samples  taken of the sediments in both
elevated bins and in the effluent from the bins (influent to the hydrocyclones) .

According to ideal settling theory, the elevated bins could be expected to
settle out all particles down to approximately  100 microns in size. The data
in Tables C-3 and C-4 indicate that a substantial  portion of the material below
75 microns in size was also settled out in the bins. In the first bin, approx-
imately 26 percent of the trapped sediment was less than 75 microns in
diameter.  In the second bin, about 36 percent, on the average, of the trap-
                                   31

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ped particles were below 75 microns in diameter.  Table C-5 in Appendix C
shows the grain size distribution of the solids in the effluent from the bins
(influent to the hydrocyclones) .  It shows that almost all of the particles
over 105 microns in diameter remained in the bins.  Thus, as evidenced
by these data, the elevated bins performed better than expected in that
almost all of the particles down to the expected size  (100 microns) were
removed as well as an additional fraction of the particles below 100 microns
in size.

The factors which produced this deviation from ideal settling theory during
the field demonstration included:

    (1)    The effects of turbulence on the settling of particles produces
perturbations from ideal settling theory.  Some small fraction of material
larger than the size expected to be  settled (in this case, 100  microns)  can be
expected to be lost over the overflow due to turbulence. However, a lar-
ger fraction of particles below the critical size are deposited due to turbu-
lence effects.    The distribution of particle sizes settled in the bins cor-
respond roughly to those predicted by the theory of turbulence effects on
settling.
    (2)    Some collision and/or agglomeration of small size  particles with
larger-sized particles may have occurred in the turbulent  regions of the
elevated clarifier bins.  This action would either slow  down  particles or
produce larger particles,  both of which conditions would cause settling of
the smaller than critical size particles  to occur more readily  than would
normally be expected.

During  the field demonstration,  cleaning of the elevated bins was necessary
after approximately two to three hours of continuous dredging.  After this
time,  the bins were essentially full  and no additional settling occurred.
                                     32

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When this happened, the entire solids loading from the dredge flowed
through the bins directly to the hydrocyclones.  Figure 9 shows the sedi-
ment accumulated in the first bin after approximately two hours of contin-
uous dredging.

To empty the bins of sediment, the dredging operation  was shut down and
the water was decanted from the bins.  This operation was usually scheduled
for either directly before  the midday break or before final shut down at the
end of the day.  The sediment was then  allowed to dry  during the break,
and emptying of the bins through the bottom doors began immediately after
lunch or the first thing the next morning. At this time, the sediment was
never fluid enough to drop unaided into the dump trucks underneath the
bins. Therefore, standard hand-held concrete vibrators were utilized to
help fluidize and drain the sediment into the trucks.  Normally, cleaning of
both bins by this process, once the water was decanted, took two men about
one hour.  This assumes that an adequate number of trucks were available
for continuous loading.
          FIGURE 9.  Sediment Accumulated in  First Bin After
                        Two Hours of Dredging
                                    33

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Two other methods for cleaning of the sediment from the bins were experi-
mented with during the course of the field demonstration.  One involved
draining of the sediment into trucks without first decanting the water.
Utilization of this method took less time to empty the bins than it took when
the water was  decanted first,  since the sediment was more fluid.  However,
more sediment spills were created by this method since the excess sediment-
laden water either  drained away from under the bins during loading of trucks
or was spilled from the trucks during hauling.

Another bins cleaning method tried  involved the draining of the accumulated
sediment from the bottom of the bins while the processing  system was in full
operation.  This method often created an even greater amount of spilled,
sediment-laden water.  The accumulated sediment was solid enough to drain
directly onto trucks during full system operation.  However, precise control
needed to be exercised on the dump gates since once the solids were drained,
the dredged slurry in the bins began to rapidly drain out  the open gate,
creating a muddy environment below the bins if much was allowed to drain out

These two alternate methods of bin  cleaning,  although faster than the one
in which the bins were decanted of water, were judged to  be more messy.
Consequently, the  "cleaner" but slower method of bin cleaning by  first de-
canting  the water was the one primarily utilized during the remainder of
the field demonstration.

Hydrocyclones

The feed to the hydrocyclones averaged 131,200 mg/l of suspended solids
during the field demonstration. Approximately 74 percent of these solids
had a particle  size  less than 75 microns in diameter  (Table C-5), that is,
the large majority of the solids loading  to the hydrocyclones was in the

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silt and clay range.  The solids concentration in the underflow averaged
about 10 percent over the course of the entire field demonstration.

Some observations on the efficiency of the hydrocyclones in processing
the sediment at the field demonstration  site are:

     (1)   The hydrocyclones were not as efficient in removing suspended
solids as anticipated. This was thought to be due to two factors present
during the demonstration:  the high influent solids loadings and the small
particle sizes in the  influent. Both of these factors are thought to have
reduced the efficiency of removal of the hydrocyclones.
     (2)   The use of a closed underflow  header with silt collection pots
and automatic solids  unloading is probably not justified in a portable sedi-
ment processing system. The higher underflow solids loadings anticipated
through use of this configuration did not  materialize, probably due to the
factors mentioned in  (1) above.

A recently completed study on the use of hydrocyclones for the processing of
dredged slurry also  arrived at conclusions similar to the observations in  (1)
above.  The study concluded that the hydrocyclone is not applicable to dredged
spoils with high solids contents and high viscosity at low shear rates.  Sand
spoils with low organic content were applicable for separation by a hydrocy-
clone.  It was also recommended that the  influent have a suspended solids
                                     2
concentration of less than 10,000 mg/l.

The  use of hydrocyclones in dredged spoil processing systems should thus
be limited to the separation of particles down through the sand size range,
that  is, 74 microns or greater in size.  Within these constraints, hydrocy-
clones  should prove  even more efficient in removing suspended solids than
was  demonstrated during the field trials under this program.
                                    35

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Cartridge Filter Unit

Cartridge filters are generally designed and utilized as polishing filters.  In
such applications, they are usually used to produce effluent water of drinking
water quality from influents which contain at most a few thousand mg/l of
suspended solids. Thus, the operating conditions to which the cartridge
filter unit was subjected  during the field demonstration, when it was sub-
jected to an average  influent of 88,300 mg/l, far exceeded its design capacity.
As a result, frequent backflushing of the filters was necessary.  This was
done at six-minute intervals for the majority of the demonstration program.
Even at this frequent rate, the cartridge filters frequently blocked-up with
sediment prematurely, causing excessive backpressure to build  up in the
system and the total system flow rate to consequently decrease.

Midway through the field trials, the internals of each filter unit were thor-
oughly inspected. This inspection  revealed a  buildup of sediment in the
"dead water" areas of each filter unit as well as a number of broken filter
cartridges. Of the 204 total cartridges which were in the four subunits,  20,
or approximately 10 percent were found to be broken.  It was speculated
that excessive backpressure during backflushing caused the cartridges to
rupture.  The broken cartridges were replaced and the cartridge filter unit
was placed back in operation.

Broken  cartridges were speculated  to be the cause of the relatively dirty
effluent from the unit.  Frequent spot inspections  revealed  continuing break-
ing of cartridges while trying to maintain adequate system flows. Therefore,
the usefulness of the cartridge filter unit in such a processing system was
marginal.  Operating and maintenance restrictions would probably preclude
the widespread utilization of such units unless the suspended solids  concen-
tration in  the dredged slurry could  be reduced to near the design level of
                                     36

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the units.  Such a situation might arise if the dredged material consisted of
mainly sand-sized and larger particles and these particles were effectively
removed before being fed to the cartridge filters by clarifier tanks and/or
hydrocyclones.  In such a situation,  the cartridge filters would be perform-
ing the polishing function  for which they were designed.

Uni-Flow Filter
The Uni-Flow filter, a fabric hose type filter, proved to be very effective in
removing suspended solids from a dredged slurry during the field demon-
stration. The Uni-Flow delivered a very good effluent:  as  low as 47 mg/l
of suspended solids, with a  normal average of a few hundred mg/l unless a
hose burst or a puncture developed in a hose and the effluent water quality
deteriorated corresponding.

It was observed during the field demonstration that the average effluent
quality could have been even better if an inexpensive, easily  installed,
completely watertight method of fastening the ends of the hoses to the pipe
nipples  could be found.  Minor but numerous leaks were observed to occur
around the hose clamp and gasket seals which fastened the hoses to the
nipples  in the six Uni-Flow filter headers.

After three weeks of operation, the hoses became so blocked with sediment
that the installation of a completely new set of hoses became necessary.
Previous to this, simple shaking of the hoses by hand after the sediment had
dried was tried as a simple maintenance cleaning procedure.  Although this
method produced acceptable results in that the sediment was loosened from
the sides of the hoses and fell into the sludge collection hopper, it proved to
be very time consuming.  Blockage of a large number of the hoses occurred
daily, but daily maintenance cleaning of the hoses in this manner proved
                                    37

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too costly and time consuming.

The small diameter hoses appear to have caused bridging of the sediment.
Figure C-1 in Appendix C shows the amount of hoses which were found to
be completely bridged by sediment when the hoses were changed after
three weeks of operation.  Out of the 720 total hoses, 484 or 67.2 percent
were completely blocked with sediment. No significant pattern of bridging
was found to exist.

The average flow through the system over the entire field demonstration of the
system was approximately 220 gallons per minute.  This is only about one-half
of what was  originally expected. The two limiting factors for the flow rate
were the blockage of the Uni-Flow filter hoses and the build up of backpressure
in the cartridge filter unit. Only when completely new hoses  were  installed
on the Uni-Flow filter and the cartridge filter unit was thoroughly flushed
with clean water did the flow rate of the system during the processing of
dredged  slurry approach 500 gallons per  minute.

The high efficiency of suspended solids removal of the Uni-Flow filter yet
the accompanying quick blockage of its hoses when fed a concentrated slurry
was illustrated  in Table 7.  This table presented the summarized results of
the processing of the dredged slurry utilizing only the elevated bins and the
Uni-Flow filter.  When this test was stopped, essentially all of the hoses were
blocked with sediment and would have had to be changed if further utilization
of the Uni-Flow was desired.

The promise which the Uni-Flow filter demonstrated during the field trials
prompted further investigations into its use as a filter for suspended solids.
Additional experiments were performed on a small prototype test stand after
the field demonstration was completed.  These tests concentrated on larger
diameter  hoses in order  to prevent the blockage problem with the small, one-
inch diameter hoses which  was experienced during the demonstration of the
                                    38

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portable sediment processing system in the field.  The results of these larger
diameter hose tests are presented in Section VII.

COSTS

Table 9 shows the capital costs of the major components of portable sediment
processing system and the various pieces of required auxiliary equipment
which were used in the field demonstration. Similarly, Table 10 is a com-
pilation of the operating and maintenance costs incurred during the six-week
field demonstration of the system, excluding the costs of trucking the sedi-
ment from the elevated bins.

As is seen from Table 10, the operating and maintenance costs of the overall
system were  $4.23 per cubic yard of sediment removed.  This relatively high
cost was due to a number of factors, all of which were directly  related to the
amount of labor required.  The factors which required a labor-intensive
effort were:

    (1)   Changing of the Uni-Flow filter hoses
    (2)   Removal of sediment from the bins
    (3)   Cleaning and replacing filter cartridges

Since the system demonstrated in the field was a prototype system, it is
probable that the operating and maintenance costs could be reduced by
approximately 30 percent through the judicious streamlining of the system.
Suggestions for streamlining of the system include:

    (1)   Elimination of the cartridge filter unit
                                    39

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         Table 9.  CAPITAL COSTS OF THE PORTABLE SEDIMENT
         	PROCESSING SYSTEM	

Item                                                        Cost C$)
                 \ -,
Elevated Bins:  ganged together with common central
  columns and air operated gates                              7,300

Hydrocyclones:  assembly including six 4-inch cones
  with replaceable urethane liners, 3 gal. silt pots, a
  closed underflow  header,  and automatic, air-actuated
  solids unloading                                            4,987

Cartridge Filter Unit: assembly including four units
  with 51 cartridges each and automatic,  air-actuated
  backflushing in sequence                                    7,875

Uni-Flow Filter:
  basic assembly                    $10,450
  header valves                          55
  sludge dump valve and actuator         319
  cycle timer and box                     33
  720 10' polypropylene hoses  @30C/yd    720
  1440 hose clamps  & tape gaskets         203
  pressure gages and protectors           63_

                      Subtotal       $11,843                 11,843

Pumps:
  1-500 gpm @ 200 ft. of head             858
  1-500 gpm @ 25 ft.  of head              579
  1-gasoline for bin  decanting            101

                     Subtotal       $ 1,538                  1,538

Air compressor:  including hoses,  regulator,  couplings,
  and filter                                                    637

Miscellaneous Equipment: including connecting and bypass
  piping, flanges, valves, overflow pipe, railroad ties,
  sludge culvert, etc.                                         2,045

                                          TOTAL          $  36,225
                                    40

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        Table 10. SIX-WEEK OPERATING & MAINTENANCE COSTS
           OF THE PORTABLE SEDIMENT PROCESSING SYSTEM
        	(Excluding Trucking)	

Item                                                       Cost($)
Elevated Bins:  rental of concrete vibrators                     180

Hydrocyclones:                                               0

Cartridge Filter Unit:  20 replacement cartridges
  @$3.50ea.                                                 70

Uni-Flow Filter: 730, 10' replacement hoses @ 30C/yd           730
                1460 tape gaskets                              8

Labor: 600 man-hours @ $5. 35/hr. av.                       3,210

Miscellaneous:  electricity, gasoline for air compressor,
  etc.                                                        3jO

                                         TOTAL           4,228


Cost per  cubic yard removed by system = 4228/1000 = $4.23 per cubic yard

Cost per  cubic yard removed, excluding labor = 1018/1000 = $1.02 per cubic yard
                                   41

-------
(2)    Utilization of a Uni-Flow filter with larger diameter hoses to
      eliminate the hose blocking problem
(3)    Investigation of applicable available equipment or alteration of
      equipment to permit automatic solids unloading at an  acceptable
      moisture content from the initial solids removal stage clarifier
      tanks.

-------
                        SECTION VII
       ADDITIONAL TESTS - LARGE DIAMETER FABRIC
                       FILTER HOSES

BACKGROUND

Fabric filter hoses of greater than one inch in diameter were tested and eval-
uated on a separate system after the  field demonstration of the portable sedi-
ment processing system was completed. The project was  undertaken for the
purpose of determining whether larger diameter fabric filters  exhibit perfor-
mance characteristics superior to those of one-inch diameter fabric filters.
The investigation centered on the use of the fabric filters  for the  clarification
of suspended sediment slurries and the concentration of the sediment sludge.
In particular,  larger diameter filters were investigated for their ability to
resist bridging with sediment,  the cheif problem with the smaller diameter
fabric filters.  In addition, the larger diameter filters were tested for:

    (1)   Filtration rate, expressed as the ratio of gallons per minute
of effluent to square feet of filter surface area.
    (2)   Pressure handling ability (psi)
    (3)   Tendency of the filter tubes to bow with increased pressures
(deflection in  inches)
    (4)   Quality of the effluent (milligrams per liter of suspended solids)
    (5)   Total  effluent flow (gallons per minute)
    (6)   Filtration cycle time (time between backflushes)
    (7)   Ease of cleaning during a  normal  backflush (sludge draining)
cycle.

The sediment used in the influent slurry was made from a mixture of sand and
the finer silts  and clays.  These materials were taken from dredged spoil
disposal  areas and mixed to simulate typical dredged slurries. Appendix D
contains  the measured particle  size distributions of the influent solids for
various large diameter hose tests.

Five-inch nominal diameter hoses were selected for testing. This size was
selected because it is one of the standard diameter bags which are used in

-------
air bag houses for stack gas filtering. The underlying consideration during
the large diameter hose test program was to investigate the adaptability of
standard air bag technology to the water filtration field, and in particular, to
the processing of slurries with high suspended solids concentrations. If
larger diameter hoses proved  feasible for water filtration,  available, off-the-
shelf equipment might then be adapted to solve a current problem.

Four different fabrics were initially identified as being potentially applicable
to water filtration and were subsequently tested.  These were:

     (1)   Multifilament polypropylene
     (2)   Nylon
     (3)   Nylon with a sateen weave
     (4)   Homopolymer acrylic

The apparatus  for testing of the nominal five-inch diameter fabric filter
hoses is shown in Figure 10.  Basically it consisted of:

     (1)   Fabric filter hose column test stand.
     (2)   Elevated bin  for influent slurry.
     (3)   Influent pump.
     (4)   Effluent bin.
     (5)   Hose internal pressure gauge.
     (6)   Effluent flow  meter.
     (7)   Influent sampling valve

Testing was performed in two  phases. In the first phase, the four fabric
filter materials were subjected to tests of about 1 hour in length,  and the
results of the tests were compared to determine the fabric material which
exhibited the best performance characteristics in terms of the seven hand-
ling characteristics described above.
                                    44

-------
   Flow
   Meter
Effluent
 Backflush
              9-1/2'
— ^-
ği
— ğ -
>
'/

5"

5"
8"




Fabric Filter
-~^ Hose
—5-1/4"
1" — *-
Effluent Reservoir
? Pressure
Cage

' 	 ,
— T
U i
D
Sample r
	 _J Port J
Control Valve Fc
*^ Filter Rinse
m^c^i
Sediment
Slurry
Reservoir
1-1/2"—^
/^
—

                          Quick-Open
                          Backflush Valve
Influent Pump
 FIGURE 10.  Large Diameter Fabric Filter Hose Test Apparatus

-------
During this phase of the testing, three different backflushing, that is, sludge
drainage and filter washing methods were also experimented with:

      (1)   A simple one-time draining of the hose.
      (2)   A simple one-time draining of the hose followed by an internal
washing  of the hose by allowing approximately five to six gallons of influent
water to wash down the inside of the hose.
      (3)   Multiple draining and refilling of the hose during the backflush
 cycle.

In the second phase, the best-performing fabric was  subjected to a series of
tests in which the operating and physical parameters of the hose were varied
to provide more detailed information on the performance of the filter. The
parameters that were varied were:

      (1)   Type of backflushing operations
      (2)   Presence of wire mesh  cylinder inside filter column
      (3)   Presence of wire mesh  cylinder outside filter column
      (4)   Presence of wire mesh  cylinder outside and inside filter column
      (5)   Length of the fabric filter column
      (6)   Time duration of the test
      (7)   Suspended solids concentration of the influent

The wire mesh cylinders were added so that their effects on the performance
of the filter as indicated by effluent quality, backflushing time, and filtration
rate as well as pressure handling ability could be investigated.  The basic
function of the wire mesh cylinder was,  in the case of the external cage, to
impart increased rigidity to the filter  column to enable it to withstand higher
pressures and thus, hopefully,  produce a greater effluent flow with the same
quality;  and to prevent the fabric filter from collapsing during backflushing,
thus helping the sediment deposited on the hose to be washed off, when the
wire cage was placed inside the filter  hose.

                                    46

-------
The length of the fabric filter column was shortened from a nominal ten feet
to eight feet towards the end of the testing program.  Wire mesh cylinders
were placed both inside and outside the shortened fabric filter column and
remained in place for all tests of the eight foot long filter. The eight-foot
filter was always tested with wire mesh on both the inside and outside of the
tube.

Three tests of the eight-foot long filters were conducted. The first was a
short duration test of approximately one hour, and the second and third
together were a  long duration test of about five hours.

TEST PROCEDURE

The procedure for testing the nominal five-inch diameter fabric filter hoses
is described  in the following steps:

      (1)   An  influent slurry was mixed in the sediment reservoir to the
approximate desired concentration of suspended solids.
      (2)   The influent pump was started.
      (3)   When the influent water reached the top of the fabric filter column,
the time was  recorded, samples of the influent and effluent were taken simul-
taneously, and readings of the pressure gauge and flow  meter were taken
simultaneously and recorded.
      (4)   The pressure was  recorded at two minute intervals for short
duration tests and ten minute intervals for the long duration test.  Flow
readings were taken continuously.
      (5)   Backflushing was performed when the flow  rate fell to below  one
gallon per minute.
      (6)   After backflushing, the procedure began  at step  three (3) again.

After all  samples were taken, laboratory analyses were performed to deter-
mine the concentrations of suspended solids  in the influent and effluent

-------
samples, using the procedure in part 224C, Total Suspended Matter,  in
Standard Methods For the Examination of Water and Wastewater.
TEST RESULTS
First Phase

A summary of the results of the first phase of the five-inch diameter hose test-
ing in which the four different fabrics were tested is given in Table 11.  At
the conclusion of the first phase tests it was evident that the  multifilament
polypropylene fabric performed the best,  both in terms of the effluent quality
and the average flow rate through the hose.  All of the first phase tests sum-
marized in Table 11  were performed utilizing the filter wash  from the top of
the hose during the  backflush cycle. The average pressure, and consequently,
the average flow rate at which the polypropylene hose was tested was higher
than the other three fabrics could be tested at.  This was because the poly-
propylene did not bow out as much under  pressure.  This bowing of the hose
          Table 11.  SUMMARY OF FIRST PHASE FIVE-INCH
          	UNI-FLOW HOSE TESTS	

Fabric Filter     Effluent Quality    Influent Quality    Aver.    Aver.   Aver.
  Type       (mg/l susp. solids)  (mg/l susp.  solids) Pressure Flow  Filtration
                                                                   Rate   2
              Max.  Min.  Avg.    Max.  Min.  Avg.   (psi)      (gpm)  (gpm/ft )

Polypropylene  740   0    95   19,950 1940  5065    11.2      3.2    0.23
Nylon         1260  205  525    3,555  540   1445     6.7      0.8    0.06
Homopolymer
 Acrylic     3870   0    400   26,065 1095  5230    10.8      2.6    0.19
Nylon Sateen  3340   17   1500   8,080 4030  5985     9.7      2.8    0.20
                                   48

-------
was especially evident in the nylon hose, which had to be run at a very low
pressure (flow) in order to prevent its breaking away from its seals at the
ends of the test column.

Second Phase

After the polypropylene fabric was determined to be the most suitable for
the filtration of suspended solids of the fabrics tested, experiments were
conducted in order to better define the operating parameters and to try to
optimize the performance of five-inch polypropylene hoses. The goal  of
this second phase of five-inch  hose testing was to maximize the flow rate
through the hose yet maintain a high overall effluent water quality. An
additional consideration was to reduce the operational hardware require-
ments of any full scale prototype as much as possible.

In order to reduce the hardware requirements, washing of the filter from
the top was eliminated during the second phase tests, and a simple draining
of the hose during backflushing was substituted instead.  This simple drain-
ing of the tube did not produce as clean a hose as with a wash from the top,
and consequently the average flow rates of the nonrinsed hose were corres-
pondingly lower.  Filling and draining the hose a number of times during
the backflush cycle was also tried and produced a somewhat cleaner hose, but
the amount of backflush water  required was more than the hose throughput.
The sequence of testing during the second phase involved first the testing
of the wire cages on the inside, outside, and both inside and  outside of the
hose, and the reducing the length of the hose  to eight feet. In all tests
during the second phase, the hoses were run  until their flow dropped below
0.9 gpm, at which time they were backflushed and the tests continued.  The
reduction in length was designed to see if a somewhat shorter hose would
produce the approximate same  flow rate as a 10-foot long hose.  A shorter
                                    49

-------
hose would require less supporting superstructure in a full-scale filter.  The
wire cages used were built of galvanized,  16-gage welded wire fencing with
openings of 2" x 2  5/8".

Table 12 presents a summary of the results for the entire second phase of
testing.  In order to compare the performance of the hoses under approximately
the same test conditions, the tests in which the concentration of suspended
solids in the influent was approximately 10,000 mg/l were analyzed.  A
summary of these  tests is presented in Table 13. As can be seen from this
table, the addition of wire cages to the polypropylene  hose did not produce a
substantial increase in flow at the 10,000 mg/l influent level.  However,
reducing the length of the hose to eight feet did not substantially reduce the
flow rate at this influent concentration.  The average effluent quality for
all tests summzaized in Table 13  (influent concentrations of approximately
10,000 mg/l) were comparable.

Figures 11 and 12 are plots of the flow and effluent concentrations respec-
tively, on the last  long duration test on the eight-foot  long hose with cages on
both the inside and outside. These figures show the typical flow and effluent
quality patterns evident during the test program.  As  seen on Figure 11,
immediately after backflushing the flow increases  to some higher point, and
then decreases as sediment builds up on the  inside of the hose.  As the
sediment builds up on the inside of the hose the flow rate drops.   Back-
flushing washes the accumulated sediment from  the hose and the flow rate
again increases.  During the test shown in Figure 11,  the  hose was back-
flushed when the flow rate fell below approximately 0.9 gpm.

The effluent quality is usually low after a backflush and becomes better
as the sediment forms a coating on the inside of the hose.  However, as seen
from Figure 12, the effluent quality did hot follow as regular a pattern as the
flow rate curve. This may be due to a number of factors,  such as variance
in the cleansing action of the backflushes, amount of soil particles trapped
within the fabric,  soil particle agglomeration, etc.
                                   50

-------
                   Table 12.  SUMMARY OF RESULTS OF SECOND PHASE
                          POLYPROPYLENE TESTING




c
E
3
23
1
il


c
3
o
eo U
j_
0)
il


Test Parameters



No Cages


Cage Outside
Cage Inside

Cages Outside &
Cages Outside &
ITest 1

Cages Outside £
Test 2

Cages Outside £
Test 3
Table
Average
Influent
Concen.
(mg/l)
7,765


7,840
25,480

Inside 11,685
Inside 18,200


Inside 8,990


Inside 11,640

Average
Effluent
Concen.
(mg/l)
1020


605
980

1580
1220


520


330

Average
Flow Rate

(gpm)
1.4


1.3
1.5

1.2
1.1


1.2


1.2

Average
Test
Pressure
(psi)
16.0


18.5
18.5

17.5
19


19


20

13. SUMMARY OF RESULTS OF SECOND PHASE
POLYPROPYLENE TESTING
FOR INFLUENT CON-
CENTRATIONS NEAR 10,000 mg/l




c
3
23
i_
0)
•M


c
3
0
w U
Test Type



No Cages

Cage Outside

Cage Inside
Cages Outside
Cages Outside
(Test 1

Cages Outside
Average
Influent
Concen.
(mg/l)
9995

8310

9330
& Inside 9090
& Inside
7830

£ Inside 9575
Average
Effluent
Concen.
(mg/l)
665

275

240
1030

1420

750
Average
Flow Rate

(gpm)
1.5

1.2

1.8
1.3

1.2

1.3
Average
Test
Pressure
(psi)
16.0

18.5

18.5
17.5

20.0

19.0
il
     Test 2

Cages Outside  & Inside  9885
     Test 3
                                          160
1.3
20.0
                                   51

-------
     5.0 -1
     4.0
     3.0
tn
NJ
2.0
     1.0
      ?
      Q.
      O
      U.
                                                                                    81 polypropylene,cages inside and
                                                                                    outside
                                                                                    average pressure = 20/psi
                                                                                    /\ = beginning of backflush
                                                                                           A  A  A  A     AAAA    A
—r~
 60
                    20
                            40
80          100         120
          Time (Min.)
140
160
—I—
 180
200
                                              FIGURE 11. Flow vs. Time  (Eight-Foot Hose)

-------
Ln
U>
         400.
         200
                                                                                      8' polypropylene ,cages
                                                                                      inside and outside
                                                                                      Average pressure = 20 psi
                                                                                      A = beginning of backflush
                       ~r
                       20
40
A 60
80
              T
100A          120
Time  (Min.)
~T
140/j
                                                                                                          160  A  rt  /\ 180^,    A A  200
                                            FIGURE  12.  Effluent Concentration vs. Time (Eight-Foot Hose)

-------
OBSERVATIONS AND ANALYSES

Blockage by Sediment

The nominal five-inch diameter fabric filters tested all developed a build-up
of sediment of less than one-quarter of an inch at the point where the effluent
flow had decreased to just less than 0.9 gpm.  Consequently,  there was no
blockage of the fabric filter columns with sediment.

Shedding of Sediment During Backflushing

All fabric filters tested shed most of the built-up sediment during simple-
draining backflushing (no rinsing from the top) .  However, backflushing
with rinsing from the top produced a cleaner filter and consequently a greater
average flow rate than when rinsing from the top was not used.  The instal-
lation of a wire cage on the inside of the hose helped the hose  to shed sedi-
ment during the simple-draining backflush used during the second phase.
The cage prevented the collapse of the hose during draining.  Collapse of
the hose prevented the sediment from sliding off the side of the hose.

Filtration Rate
                                                                  2
The filtration rates for the fabric filters tested ranged from 0.07 gpm/ft
for the second phase tests to a maximum of 0.44 gpm/ft  for the first phase
tests.  Filtration rates for the large diameter fabric filters are compared to
the filtration rates of previously tested one-inch diameter fabric filters  in
Table 14.
                                54

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                  Table 14.  PERFORMANCE HISTORY OF UNI-FLOW FABRIC FILTERS
en
en
Test



Aqua- Ion Corp.
1" dia. testing
Fabric Type-
Influent


Cotton -Ac id
Mine Drainage Waste
Operating
Pressure
Range
psi
12-20

Filtration
Rate
Range
gpm/ft
0.13

Average
Operating
Pressure
psi
12-20

Average
Filtration
Rate
gpm/ft
0.13

model (EPA Contract No. 68-01-0043)
Hittman Assoc.
1" dia. testing
model	

Hittman Assoc.
1" dia. full
scale proto-
type field tests

Hittman Assoc.
5 1/4"  dia.
testing model
                          Cotton-Sediment    5-33
                          Slurry
                          Polypropylene-     5-12
                          Sediment Slurry
                          Polypropylene-      10-23
                          Sediment Slurry
0.05-0.13
0.06-0.19
0.07-0.44
11
10
12
0.06
0.13
0.24
0.11
0.13
                                      **
                                      ***
              10' long, rinsed from top
              10'long, not rinsed from top (simple draining)
          *** 8' long, not rinsed from top
**

-------
The ten foot long polypropylene filters which were rinsed from the top during
backflushing had the highest average filtration rates. The filters which were
not rinsed during backflushing exhibited filtration rates of about one-third to
one-half the filtration rates of the filters which were rinsed during backflush-
ing.  Filters tested in the first and second phases are ranked in order of
decreasing filtration rates in Table 15.

Operating Pressure

The 10-foot long polypropylene fabric filter columns were tested at a maxi-
mum pressure of 15 psi.  The 10-foot polypropylene fabric filters which in-
corporated wire mesh columns on the inside and outside were tested at an
average pressure of 18.5 psi.  The eight-foot long fabric filter columns in-
corporating wire mesh columns both inside and outside the filter column
were tested at an average pressure of 20 psi  and withstood a maximum oper-
ating pressure of 24 psi.

With increased pressure, the fabric filter columns bow outwards such that
deflection from the centerline of the filter columns increased with increased
pressures.  Deflections of up to 12 inches were measured in  the polypro-
pylene fabric hoses at high pressure, and similar deflections were measured
at much lower pressures for the other fabric hoses.  Cages on the outside of
the hoses prevented this bowing.

Effluent Quality

The effluent quality of the various configurations  of polypropylene hoses
tested followed comparable cycles during the tests. The quality was usually
lowest immediately following a backflush and improved as the hose became
coated with sediment.  A decrease in the average  effluent quality was  evident
                                    56

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Table 15.  FILTRATION RATE RANKING OF POLYPROPYLENE FABRIC FILTERS
Polypropylene
Parameters
10
10
8'
10
10
10
1 long
1 long
long.
1 long
1 long
1 long
Filter
, no cages, rinsed from top
, cage
cages
inside
inside and outside
, no cages
, cages inside and outside
, cage
outside
Filtration Rate Average Effluent Average Time Between
(gpm/ft ) Quality (mg/ 1) Backflushes (min.)
0
0
0
0
0
0
.24
.13
.13
.11
.10
.09
95-140
240
750
665
1030
275
10-16
5
8
10
2
4

-------
when cages were added to the outside of the fabric filter column.

Filtration Cycle Time  (Time Between Backflushes)

Filtration time between backflushes was greatest for the tests of ten-foot long
polypropylene fabric filters which were rinsed from the top.  It should be
noted that the times between backflushes reported for these tests are from
the time when the influent slurry reached the top of the filter to the time when
the effluent flow was two and one-half gallons per minute as opposed to the one
gallon per minute criteria for backflushing in the other tests.  Therefore, the
time between backflushes for the ten foot long polypropylene  filters which
were rinsed from the top would have actually been much greater than the
values reported  if backflushing had been initiated when the effluent flow  fell
to below one gallon per minute.

The filtration times between backflushes for the ten-foot long filters in the
second phase of testing were  very much lower than the filtration time between
backflushes for the ten-foot long polypropylene filters of the first phase.
During this second phase, as seen from Table  15, the tests of ten-foot long
filters with both no cages and a cage only on the inside produced a higher
average filtration time between  backflushes than the two configurations of
filters with wire mesh outside the column.  As discussed previously, wire
mesh inside the  filter column  increases the filtration time between required
backflushes.

A comparison can be made between the tests often and eight-foot long filters
with wire mesh both inside and outside the filter column.  The shorter filter
exhibited average backflush times of one and one-half times those for the
longer filter when considering the results of the entire tests.  However,
the second test on eight foot long fabric filters was performed on a thoroughly
                                   58

-------
cleaned filter.  The average backflush time for the rinsed filter increased
by about five times over the backflush time for the previous test of  the
unrinsed filter, considering results for the entire tests.

A third test on the eight-foot filter was started after the rinsed filter of the
second test had operated for two hours.  At thirty minutes into the third
test, the backflush time had decreased to the range of backflush times found
for the first test.  Therefore, in two and one-half hours, the performance of
the rinsed  filter deteriorated to the performance level of one used extensively
without rinsing.

The backflushing method was varied at certain times during the long term
test of the eight-foot filter so that immediately after the concentrated sediment
slurry had been discharged from the filter, influent water was pumped into
the filter from the bottom and the quick-open backflush valve was opened
when the water level reached the top of the filter column.  This procedure is
evidenced  by the relatively short times between  backflushes shown  toward
the end of Figures 11 and 12.
                               59

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                             SECTION VIII

                             REFERENCES
1.         Camp, T. R.  Sedimentation and the Design of Settling Tanks.
          Transactions of the American Society of Civil Engineers.
          111: 895-958, 1946.

2.         Tiederman, W. C., and M. M. Reischman, Feasibility Study of
          Hydrocyclone Systems for Dredge Operations.  Oklahoma State
          University. Vicksburg, Mississippi,  Contract Report D-73-1.
          U. S. Army Engineer Waterways Experiment Station.  July 1973.
          176 pp.

3.         Taras, M.  J . , A. E. Creenberg, R. D. Hoak,  andM. C. Rand,
          eds.  Standard Methods for the Examination of Water and Waste-
          water, 13th edition. Washington, D.  C., APHA, AWWA, and WPCF
          August 1971.  p.  537-538.
                                   60

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                             APPENDIX A
This Appendix contains the detailed background data on the quality of the
pond water before dredging began and basic data on the water quality par-
ameters of the dredged slurry.  These data were collected as part of the base-
line survey.
                                   61

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            Table A-1.  POND WATER QUALITY BEFORE DREDGING OPERATIONS
Constituent


Sulphate
Phosphate
Iron
Copper
Zinc
NH3
COD
Total Nitrogen
Coliform (Presumptive)
pH
Suspended Solids
Volatile Solids
Total Dissolved Solids
Total Solids
Turbidity (JTU)
Concentration (mg/l unless stated
Location*
1 2 3
10 - 23
0.9 - 0.7
0.45 - 0.3
0.35 - 0.3
0.00 - 0.01
0.8 - 0.7
3.4
12.0 - 9.0
Positive 5/5
6.0 - 6.75
381
531 - 67
57
2980 - 505
130
otherwise)

4
50
1.4
0.7
0.5
3.25
1.6
7.6
13.0
-
6.1
745
68
21
834
135


5
28
0.2
0.25
0.15
0.00
0.4
1.6
14.0
-
6.1
37
42
48
137
13
 Oxidation-Reduction Potential (mv)    50
60
75
20
* Location Description:

1    -   Pond inflow  from  watershed
2,3  -   Near the inflow and of the pond

4    -   Near the discharge end of the pond

5    -   Pond discharge
                                        62

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      Table A-2.  ANALYSIS OF  COMPOSITE POND WATER SAMPLE

Constituent                 Concentration (ppm unless stated  otherwise)

Zinc,  as Zn                                     0.0
Chlorinated Hydrocarbons                     0.000
Oil and Grease                                   24
Total Organic Carbon                             12
Mercury, as Hg                                 0.0
Lead, as Pb                                    0.0
Oxidation-Reduction Potential                     -4  mv
Total Dissolved Solids, @ 105° C.                 148
Phenolphthalein Alkalinity, as CaCO                0
Total Alkalinity,  as CaCO                         36
Carbonate Alkalinity, as CaCOs                     0
Bicarbonate Alkalinity, as CaCO                   36
Carbonates, as CO3                               0
Bicarbonates, as HCO3                         43.9
Hydroxides, as OH                                0
Carbon Dioxide,  as CO2                           6
Chloride,as Cl                                   42
Sulfate, as SO4                                  52
Fluoride, as F                                  0.0
Phosphate, as PO4                              0.3
pH (Laboratory)                                 7.1
pHs                                            8.8
Stability Index                                 10.5
Saturation Index                               -1.7
Total  Hardness,  as CaCO3                       39
Calcium Hardness, as CaCO3                      18
Magnesium Hardness, as CaCO3                   21
Calcium, as Ca                                  7.2
Magnesium, as Mg                              5.1
Sodium, as Na                                  9.6
Iron,  as Fe                                     5.6
Manganese, as Mn                                0
Copper, as Cu                                 0.02
Silica, as SiO2                                    6
Color, Standard  Platinum Cobalt Scale             65
Odor Threshold                                   °
Turbidity, Jackson Units                        20
                                   63

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     Table A-3. ANALYSIS OF COMPOSITE DREDGED SLURRY SAMPLE

 Constituent                 Concentration (ppm unless stated otherwise)

 Zinc, as Zn                                    0.0
 Chlorinated Hydrocarbons                     0.000
 Oil and Grease                                 7. 5
 Total Organic Carbon                            68
 Mercury, as Hg                                0.0
 Lead, as Pb                                    0.0
 Oxidation -  Reduction Potential                  +14 mv
 Total Dissolved Solids, @ 105° C.                  77
 Phenolphthalein Alkalinity, as CaCO3               0
 Total Alkalinity, as CaCO3                        15
 Carbonate Alkalinity, as CaCO3                    0
 Bicarbonate Alkalinity. as CaCO3                  15
 Carbonates, as CO3                               0
 Bicarbonates, as HCO3                         18.3
 Hydroxides, as OH                                0
 Carbon Dioxide, as CO2                         200
 Chloride, as Cl                                  30
 Sulfate, as SO4                                  39
 Fluoride, as F                                  0.0
 Phosphate, as PO4                             0.55
 pH (Laboratory)                                5.1
 pHs                                           9.3
 Stability Index                                13.5
 Saturation Index                               -4.2
 Total Hardness, as CaCO,                        15
                       j
 Calcium Hardness, as CaCO3                      12
 Magnesium Hardness, as CaCO3                    3
 Calcium, as Ca                                 4. 8
 Magnesium, as Mg                              0.7
 Sodium, as Na                                  8.1
 Iron, as Fe                                       9
 Manganese,  as Mn                               3.7
 Copper, as Cu                                  0.0
Silica, as  SiO2                                   11
Color, Standard Platinum Cobalt Scale             80
Odor Threshold                                   6
Turbidity, Jackson Units                        100+
                                  64

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                             APPENDIX  B
Contained herein are the data collected during the investigation of the
resuspension of bottom sediments by the MUD CAT dredge during normal
dredging operations.
                                    65

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Table B-1. RESUSPENSION OF POND SEDIMENTS DURING DREDGING" 7/5/73
Operating
Condition
Before
Dredging



Dredging
(forward cut)





Distance from
Front of Dredge
(ft.)

5
5
5
5
5
5
5
10
10
20
Depth below
Surface (ft.)

1
3
5
7 (bottom)
1
5
7 (bottom)
1
5
1
Suspended
Solids Concen
(mg/l)

39
50
64
523
88
179
1260
54
86
39
                            66

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  Table B-2.  RESUSPENSIQN OF POND SEDIMENTS DURING DREDGING- 7/6/73
Operating
Condition
Distance  from
Front of  Dredge
     (ft.)
Depth below
Surface (ft.)
Suspended
Solids Concen.
   (mg/l)
Before Dredging
                       Depth Integrated  89
                       Composite -
                       0 ft. to bottom
Dredging
(forward cut)
                                       900
Dredging
(forward cut)
      10

      10
               649

               175
Dredging
(forward cut)
      20
               226
                                   67

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  Table B-3.  RESUSPENSION OF POND SEDIMENTS DURING DREDGING - 7/11/73
Operating
Condition
Distance from
Dredge  (ft.)
Depth below
Surface (ft.)
Suspended
Solids  Concen.
    (mg/l)
Before Dredging
5 ft. from front
1

4

7 (bottom)
  18

  75

1000
Dredging
(forward cut)
5 ft.  from front
                                             7 (bottom)
                  72

                1257
Dredging
(forward cut)
5 ft.  from side
                  89
Dredging
(forward cut)
1  ft. behind
                1262
                                  68

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   Table B-4. RESUSPENSION OF POND SEDIMENTS DURING DREDGING - 7/18/73
Operating
Condition
Distance From
Front of Dredge
     (ft.)
Depth below
Surface
Suspended
Solids Concen.
  (mg/l)
Before Dredging
                                      34
Dredging
(forward cut)
 5

10
               83

               19
                                 69

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                              APPENDIX C
This Appendix contains additional detailed data collected during the water
quality sampling and analysis program conducted on the portable sediment
processing system,  and other operational data on the field demonstration.
                                  70

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                        Table C-1.   SUSPENDED SOLIDS CONCENTRATIONS IN PROCESSING SYSTEM
Date
6/25/73

6/26/73


7/2/73
7/11/73


7/12/73
7/13/73

7/14/73
7/23/73
7/26/73
7/27/73
7/30/73
8/1/73
8/6/73











Suspended Solids at Sampling Point (mg/l) Average
#5 #1 #2 #3 #4 System Flow
(gpm)
158,000 29,500 * 190
* 1440
150
136
340
261,000 231,700 149,500 105,400 240
* 47
* 491
* 1127
195,200 151,200 108,000 97,200 100
76,400 52,400 * 184
254,000 254,000 179,600 50,400 227
392
129,200 61,300 40,400 26,200 230
107,600 87,600 31,400 22,700 570
107,000 67,400 44,700 26,200 660
138,000 55,800 49,500- 34,700 520
140,500 103,000 94,400 1770
+ *

158,200 135,900 + * 208

+ *

96,200 70,100 t- * 127

+ *

145,900 84,500 + * 424

300
300
250
250
250
300
250
250
250
200
200
200
250
100
100
300
250
200
250

120

70

60

50

30

Remarks
3 hr. composite samples;
2 Uni-Flow hoses with holes
sample after 1 Uni-Flow
hose burst
2 hr. composite sample
n n n
n M n
4 hr. composite samples
2 hr. composite sample
M n n
n n ii
3 hr. composite sample
2 hr. composite sample; cartridge
filters bypassed
2 hr. composite sample; bins
completely full of sediment
2 hr. composite sample; bins
completely full of sediment
composite sample of run
Composite sample of run
Composite sample of run
Composite sample of run
Composite sample of run
15 min. av. flow; Uni-Flow
pressure = 8 psi
15 min. av. flow; Uni-Flow
pressure 10 psi; 1/2 hr.
composite samples
15 min. av. flow; Uni-Flow
pressure 12 psi
15 min. av. flow; Uni-Flow
pressure 12 psi; 1/2 hr.
composite samples
15 min. av. flow; Uni-Flow
pressure = 10 psi
15 min. av. flow; Uni-Flow
pressure = !1 psi; 1/2 hr.
composite samples
f     hydrocyclones bypassed
*     cartridge filters bypassed

Sampling Point Key

# 5 = MUD CAT discharge into elevated  bins
# 1 - Bin effluent   Influent to hydrocyclones
# 2 = Hydrocyclone effluent - Influent to cartridge filters
# 3   Cartridge filter effluent - Influent to Uni-Flow  filter
# 4   Uni-Flow effluent (return water to pond)
                                                       71

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                      Table C-2.  OTHER WATER QUALITY CONSTITUENTS IN PROCESSING  SYSTEM
•-j
KJ
Date Sampling
Point
6/25/73 # 1
# 2
# 3
# 4
# 6
# 7
# 8
6/26/73 # 1
# 2
# 3
# 4
7/2/73 # 1
# 2
# 3
# 6
# 8
7/6/73 # 5
# 1
7/12/73 # 5
# 2
# 3
Sampling Point Key:
P°4







1.8
1.6
1.8
1.8
1.5
2.8
1.5
1.8
1.7
5.2
8.0
2.3
0.6
0.7
Constituent
N03- + NO.







9.0
12.0
14.0
11.0
13.0
12.0
11.0
14.0
15.0
13.0
11.0
13.0
8.0
13.0

# 5 = MUD CAT discharge into bins
# 1 = Bin effluent - Influent to hydrocyclones
# 2 = Hydrocyclone effluent - Influent to cartrii
Concentration (mg/l)
~ Fe++ SO = Total pH Turbidity (JTU)
Dis. Solids
5.9
6.0
6.0
16 5.8 153
6.0
6.0
6.0
0.35
0.15
0.35
0.27 120 140
0.15
0.10
0.05
0.10
0.10
0.75
1.50
17.0
25.0
22.0
dge filters
            # 3 = Cartridge filter effluent - Influent to Uni-Flow filter
            # 4 = Uni-Flow effluent  (return water to pond)
            # 6 = Hydrocyclones sludge
            # 7 = Cartridge filters sludge
            # 8 = Uni-Flow sludge

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    Table C-3.  GRAIN SIZE DISTRIBUTION OF SEDIMENT IN FIRST BIN
Particle Size (microns)




4760




2000




 420




 250




 105




  75




Moisture Content  =  26%
Percent Finer (7/2/73)




99.8




99.7




99.1




98.0




41.9




24.4
 Table C-4.  GRAIN SIZE DISTRIBUTION OF SEDIMENT IN SECOND BIN
Percent Finer
Particle Size (microns) Date:
4760
2000
420
250
105
75
7/2/73
100
99.3
98.4
97.4
59.9
27.3
7/10/73 7/13/73

100
100 99.9
99.9 99.8
82.8 85.0
36.5 45.0
Moisture Content = 26%
                                  73

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    Table C-5.   GRAIN SIZE DISTRIBUTION  OF SOLIDS  IN EFFLUENT
                              FROM BINS
Particle Size  (microns)	Percent Finer  (7/13/73)


          420                                    100

          250                                     99.9

          105                                     92.9

           75                                     73.6

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                                  TOP VIEW  (not to scale)
60*
(50.0%)



70*
(58.3%)


74*
(61.7%)


r^>
95*
(79.2%)
Influe
\J


nt
101*
(84.2%)



84*
(70.0%)
Overall percentage of hoses completely blocked = 67.2%
* number of completely blocked hoses out of 120 total hoses in header
(   ) = percentage of completely blocked hoses in header
                       FIGURE C-1.  Pattern of Blockage of Uni-Flow Hoses

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                        APPENDIX D

This Appendix contains the particle size distributions of the solids in the
influent for the large diameter fabric filter hose tests. Periodic samples of
the influent were taken and analyzed in order to ensure that the particle
distribution of the soil approximated a dredged slurry that would be obtained
from actual dredging operations.
                                  76

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TABLE D-1.  INFLUENT GRAIN SIZE DISTRIBUTIONS -
         LARGE DIAMETER HOSE TESTS
Test
Parameters:
Particle Size
(microns)
420
250
105
75
54
39
28
13
10
7
5
4
IG'-NoWire lO'-Wire Outside

100 100
99 89
84 66
58 46
31
28
25
18
14
10
7
3
10'-Wire

67
53
33
18
12
9
8
5
3
2
1

lO'-Wire Inside
Inside and Outside
Percent Finer
100
96
74
56
49
48
46

22
16
10
2
8'-Wire Inside
and Outside

97
92
63
32
23
18
16

5
4
2
1
8'-Wire Inside
and Outside

99
95
79
67
55
51
45
29
22
15
9
3
8'-Wire Inside
and Outside

98
88
74
67
41


23
16
11
8


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  SELECTED WATER
  RESOURCES ABSTRACTS
  INPUT TRANSACTION FORM
                                                   w
             Demonstration of The Separation and Disposal of
             Concentrated Sediments

                                                                : 5. •
  7. Author(s)
Nawrocki, Michael A.
  .9. Organization
             Hittman Associates, Inc.
             Columbia, Maryland 21045
                                                                10. PtojcctNo.

                                                                PE 1B2042
                                                   11.  Contract/Great Mo.
                                                     68-01-0743
      Environmental Protection Agency report No. EPA-660/2-Tl)—0?2, June
  In.  Abstract
             A demonstration was conducted of a system for removing and processing sedimen
   from impoundment bodies.  A MUD CAT dredge was used to remove the sediment from a
   pond.  The  dredged slurry was then pumped through a processing system consisting of a
   pair of elevated clarifier bins in series, a bank of hydrocyclones, a cartridge filter unit,
   and a Uni-Flow bag-type fabric filter consisting of 720 one-inch diameter hoses.

             The MUD CAT proved efficient in removing sediment from the pond bottom
   without imparting a substantial amount of turbidity to the pond water.  The processing
   system was  effective in removing suspended sediment from the dredged slurry.  Its
   effluent averaged 445 mg/l with an average  influent suspended solids of 170,300 mg/l.

             Experiments were also conducted on the use of five-inch diameter hoses on the
   Uni-Flow filter. These produced better results than the one-inch hoses in that they were
   not prone to blockage by sediment.
  17st. Descriptors
   *Dredging, *Sediment Deposition, *Filtering Systems, *Separation techniques.
   Impoundments, Water Quality Control, Desilting
  17b. Identifiers
    *Suspended solids separation. Pond dredging
  l~c. COWRR Field. & Group   Q^Q
  IS. Availability
                                                     Send To:
                                                     WATER RESOURCES SCIENTIFIC INFORMATION CENTER
                                                     U.S. DEPARTMENT OF THE INTERIOR
                                                     WASHINGTON, D. C. 2O24O
  Abstractor    Michael A. Nawrocki     \institution	Hittman Associates, Inc.
•fj R SIC 10 Z ! P E V J U N E 1 fl 7 1)

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