Environmental Protection Technology Series
An Executive Summary of Three EPA
Demonstration Programs In Erosion
And Sediment Control
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
-------
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.
-------
EPA-660/2-74-073
June 1974
AN EXECUTIVE SUMMARY OF THREE
EPA DEMONSTRATION PROGRAMS IN
EROSION AND SEDIMENT CONTROL
By
Burton C. Becker
Michael A. Nawrocki
Gary M. Sitek
Contract No. 68-01-0743
Program Element 1B2042
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 of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.20
-------
ABSTRACT
This report presents the highlights of three recently completed programs
in the area of sediment and erosion control. These programs were a
"Joint Construction Sediment Control Project", Project No. 15030 FMZ; a
"Programmed Demonstration for Erosion and Sediment Control Specialists,"
Project No. S800854 (15030 FMZ); and a "Demonstration of the Separation
and Disposal of Concentrated Sediments", Contract No. 68-01-0743.
The "Joint Construction Sediment Control Project" was performed in a
natural and agricultural region which was being transformed into an ur-
ban community. It consisted of the implementation, demonstration, and
evaluation of erosion control practices; the construction, operation, and
demonstration of the use of a local stormwater retention pond for the con-
trol of stormwater pollution; the construction, operation, and maintenance
of methods for handling, drying, conditioning, and disposing of sediment;
and performance of a gaging and sampling program to determine the effects
of urbanization on the hydrology, ecology,and water quality of natural
areas. In addition to the project final report, the EPA document entitled
"Guidelines for Erosion and Sediment Control Planning and Implementation11^
was also prepared under this program.
The "Programmed Demonstration for Erosion and Sediment Control Special-
ists" project developed a series of presentations on sediment and erosion
control and a certification plan for erosion and sediment control specialists.
The basic work under the project involved the development of 15 presen-
tations on various topics relating to erosion and sediment control, the con-
version of six of these presentations into the audiovisual format, the
demonstration of the program, and the evaluation of the audiovisual approach
against the conventional technical presentations with slides.
ii
-------
In the "Demonstration of the Separation and Disposal of Concentrated
Sediments" a field demonstration was conducted of a system for removing
and processing sediments from pond bottoms. The removal system consis-
ted of a MUD CAT dredge, and the portable sediment processing system
consisted of a pair of elevated clarifier bins arranged in series, a bank of
hydrocyclones, a cartridge filter unit, and a Uni-Flow bag-type fabric
filter consisting of 720 one-inch diameter polypropylene hoses. Additional
development of the Uni-Flow filter concept through the testing of five-inch
diameter prototype hoses was also performed after the field demonstration
of the sediment removal and processing system was complete.
This report was submitted in partial fulfillment of Contract No. 68-01-0743
by Hittman Associates, Inc. under the sponsorship of the Environmental
Protection Agency. Work was completed as of November 30, 1973.
in
-------
CONTENTS
PAGE
Abstract ii
Table of Contents iv
List of Figures v
List of Tables vi
Acknowledgements vi i
SECTIONS
I. Conclusions 1
II. Recommendations. 2
III. Introduction 3
IV. Joint Construction Sediment Control Project U
V. Programmed Demonstration for Erosion and
Sediment Control Specialists 24
VI. Demonstration of the Separation and Disposal
of Concentrated Sediments 37
VII. References 50
IV
-------
FIGURES
NO. PAGE
1 Aerial View of Demonstration Watershed 6
2 MUD CAT Dredge 38
3 Schematic of Sediment Processing and Sludge Disposal ^0
System
4 Initial Solids Removal: Elevated Bins 41
5 Secondary Separation: Hydrocyclones 42
6 Final Filtration: Cartridge Filter Unit 43
7 Final Filtration: Uni-Flow Filter 45
-------
TABLES
NO. PAGE
1 Reference and Experimental Subwatershed
Characteristics 21
VI
-------
ACKNOWLEDGEMENTS
Many individuals, governmental agencies and commercial establishments
contributed to the conduct and success of the programs described herein.
It would be impossible to name them all. However, the technical contributions,
project guidance, critical review, and editorial comments provided by some
of the members of this group require individual recognition. They are:
U.S. Environmental Protection Agency
Donald J. O'Bryan
Ernst P. Hall
John J. Mulhern
H.R. Thacher, Ph.D.
State of Maryland, Department of Natural Resources, Water
Resources Administration
Herbert M. Sachs, Director
Marshall T. Augustine
Roy E. Benner
Roger A. Kanerva
Robert S. Norton
Albert E. Sanderson, Jr.
Prince George's County, Maryland
William W. Gullet, Executive
Robert A. Edwards, Chief Administrative Officer
JohnH. Marburger, Jr., Director of Public Works
Paul C. Stanbus, Chief, Bureau of Roads
Howard Research and Development Corporation
William Cardwell
Vern Robbins
Cay Weinel
Robert E. Young
VII
-------
Columbia Association
James Furneas
Michael Kirby
John McDonald
Howard Osterling
Woodbine Nursery
William Pickett
Mr. William H. Amos, Consultant
Hittman Associates, Inc.
Burton C. Becker
Michael L. Clar
Dwight B. Emerson
Homer T. Hopkins
Thomas R. Mills
Michael A. Nawrocki
Gregg R. Squire
VIII
-------
SECTION I
CONCLUSIONS
The three EPA programs in erosion and sediment control described herein
have advanced the state-of-the-art of erosion and sediment control in the
areas studied to the point of practical application. Many of the results of
the programs can be directly applied to the solution of existing pollution
problems and the implementation of pollution control plans.
The EPA document, "Guidelines for Erosion and Sediment Control Planning
and Implementation," was the first comprehensive assessment of the state-
of-the-art erosion and sediment control practices and procedures.
A comprehensive instructional package for erosion and sediment control
specialists has been developed.
Methods for enhancing and disposing of dredged sediment in a environmentally
compatible manner have been demonstrated.
-------
SECTION II
RECOMMENDATIONS
It is recommended that additional work of an applied research nature be
initiated in erosion and sediment control. Demonstration projects similar
to the "Joint Construction Sediment Control Project" should be initiated in
other parts of the country in order to gather additional baseline data
applicable to other physiographic and climatic regions.
Additional field trials and applications of the equipment utilized in the
"Demonstration of the Separation and Disposal of Concentrated Sediments"
should also be pursued. This is especially true of the Uni-Flow filter,
which is applicable in a variety of wastewater treatment applications.
-------
SECTION III
INTRODUCTION
Prior to the initiation of the EPA applied research program in erosion and
sediment control, little work of a practical, comprehensive nature had
been conducted in addressing the problems associated with erosion from
construction sites and the resulting sedimentation in streams and lakes.
The programs described in the following sections have furthered the
state-of-the-art of erosion and sediment control technology in the areas of:
(1) Methods of controlling erosion on site
(2) Methods for cleaning of sediment ponds
(3) Enhancing the characteristics of dredged sediment
(4) Training of erosion and sediment control specialists
(5) Separation and disposal of solids from dredged slurries
in an environmentally acceptable manner
Practical implementation of the results generated by these programs in
many of the areas described above is now a reality. Application of the
results of these programs are presently being utilized in commercial
developments and government pollution control plans as well as in con-
tinued EPA research and development programs.
-------
SECTION IV
JOINT CONSTRUCTION SEDIMENT CONTROL PROJECT
BACKGROUND
This project was a two-year program conducted in the Village of Long
Reach, Columbia, Maryland. It was operated by the Department of Water
Resources, State of Maryland, under an Environmental Protection Agency
demonstration grant. Project No. 15030 FMZ. Hittman Associates, Inc., of
Columbia, Maryland, was the prime contractor for this project. Howard
Research and Development Corporation, the developers of Columbia, and
the Columbia Parks and Recreation Association, Inc., a nonprofit corpora-
tion representing the community used, also participated in this project.
During the period of this demonstration program, a natural and agricultural
region was converted to an urban community. This project consisted of:
1. The implementation, demonstration, and evaluation of erosion
control practices.
2. The construction, operation, and demonstration of the use
of a local stormwater retention pond for the control of
stormwater pollution.
3. The construction, operation, and maintenance of methods
of handling, drying, conditioning, and disposing of sediment.
U. A gaging and sampling program to determine the effects of
urbanization on the hydrology and water quality of natural
areas.
-------
This demonstration project was conducted within a 190-acre watershed in
the Village of Long Reach. Figure 1 is an aerial view of this watershed.
A variety of practices were demonstrated and evaluated in order to develop
general criteria and guidelines for implementation of stormwater pollution
and erosion control techniques. Specifically, it:
1. Evaluated the effectiveness and costs of conventional and
advanced methods of erosion control in urban areas
(surface landscape techniques) .
2. Evaluated the effectiveness and costs of various methods
for the transport, drying, conditioning, and disposal of
sediment.
3. Evaluated the effectiveness and acceptability of intro-
ducing stormwater and sediment retention ponds in
urban communities.
EROSION CONTROL DEMONSTRATION
Objectives
One of the principal objectives of this program was the demonstration of
advanced methods of erosion control in developing urban areas and the
evaluation of the cost and effectiveness of the methods. The goal of this
effort was the development of design, performance, and application cri-
teria that could subsequently be used by developers, planners, designers,
engineers, and builders in the development and implementation of grading,
sediment, and erosion control plans as required by the "Shore Erosion
Control Act" of the State of Maryland, and similar laws and regulations of
-------
Q REFERENCE SUB-WATERSHED
© EXPERIMENTAL SUB-WATERSHED
FIGURE 1. Aerial View of Demonstration Watershed
-------
other states, counties, and political jurisdictions. Also, the information
on the design and performance of the various erosion control techniques
demonstrated and evaluated under this program were documented for use
by regulatory agencies in the development of detailed regulations and
requirements, and for use in the review and approval of grading, sediment,
and erosion control plans submitted in compliance with such regulations.
Procedures
In order to carry out this effort it was necessary to:
1. Monitor and record the status of development. This was
accomplished through the use of aerial photographs and
repetitive benchmark photography from numerous loca-
tions throughout the demonstration area.
2. Install, apply, and monitor the performance of various
erosion control practices.
3. Install and operate sampling equipment. As a part of
this, surveys and evaluations of readily available sedi-
ment sampling equipment were conducted.
4. Collect samples.
5. Conduct surveys of eroded areas and sediment deposits.
6. Monitor and record cost and application information
required to implement control of selected practices.
-------
It is well known that erosion control practices, products, and/or techniques
must be tailored to individual sites and must be based on such factors as
topography, soil conditions, construction operations, etc. Consequently,
a wide variety of erosion and sediment control products, practices, and
techniques were investigated during the course of the demonstration pro-
ject in order to provide as large a cross section of application parameters
as possible.
In all, a total of 45 products, practices, and techniques were investigated
These can be divided into four major categories as follows:
1. Chemical Soil Stabilizers, Mulches, and Mulch Tacks
2. Erosion and Sediment Control Structures
3. Fiber Mulches, Mulch Blankets, and Nettings
4. Special Erosion and Sediment Control Practices
In addition to the above more conventional means of erosion and sedi-
ment control, the use of other less conventional ideas for erosion and
sediment control were investigated. One such idea involved the possible
utilization of recycled glass in erosion control. The conclusions drawn
from this specific investigation must be regarded as generally negative
because the need for glass to produce products that are currently on the
market (all glass brick, glass and clay brick, glass phalt, etc.) far ex-
ceeds the supply of used glass. It was further determined that, if all of
the used glass in existence could be made available for reuse in these
products, the supply would still fall short of the demand.
-------
The evaluation and comparison of the performance of the various erosion
control practices required techniques that could quantitatively measure
the effectiveness of soil retention. Part of this monitoring program in-
volved the installation of four major automatic stream gaging and sampling
stations. Data from these installations were supplemented by samples
which were collected by hand.
Results
One of the major results of the erosion control demonstration portion of
this project was the publication of the EPA document entitled "Guidelines
for Erosion and Sediment Control Planning and Implementation." The
principal purpose of the "Guidelines" is to help those responsible for, or
engaged in, urban construction prevent the uncontrolled movement of
soil and the subsequent damage it causes. The "Guidelines" presents a
comprehensive approach to the problem of erosion and sediment control
from beginning of project planning to completion of construction. It
provides:
1. A description of how a preliminary site evaluation
determines what potential sediment and erosion
control problems exist at a site being considered
for development.
2. Guidance for the planning of an effective sediment
and erosion control plan.
3. Procedures for the implementation of that plan
during operations.
-------
Technical information on 42 sediment and erosion control products, prac-
tices, and techniques is contained in four appendices. In addition, a
cross index and a glossary of technical terms used in the document are
provided.
The "Guidelines" is designed and intended for use by both technical and
lay personnel.
STORMWATER STORAGE AND TREATMENT
Objectives
A major component of this portion of the project was the demonstration of
a method of urban stormwater pollution control, using local storage and
treatment of stormwater. Even where the most advanced erosion control
techniques are employed, considerable erosion can be expected to occur in
watersheds undergoing urbanization. Among other sources, the stream
channel itself, under the influence of the greatly increased runoff, may con
tribute substantial quantities of sediment. This phase of the project was
developed to prevent this residual sediment from degrading downstream
water quality.
The major objective of this phase was the demonstration and evaluation of
local storage and treatment of stormwater as a method of controlling storm-
water pollution both during and after urbanization. In order to fully ex-
plore this application, the demonstration activities were directed to the
following:
1. Demonstration of the use of an open pond located in the
natural floodplain as a stormwater storage facility and
10
-------
primary sediment trap
2. Preliminary evaluation of advanced sedimentation
devices, such as tube settlers, for use as sediment
traps, both alone and in conjunction with the open
pond
3. Demonstration of the use of advanced sedimentation
devices, should feasibility be determined in the pre-
liminary evaluation
4. Development of design criteria for the use of open
ponds and advanced sedimentation devices for control
of stormwater pollution in urban areas
5. Preliminary investigation of the use of chemical
coagulants and coagulant aids in the control of
stormwater pollution
6. Investigation of the effect of the open pond and
other stormwater pollution control devices on
surrounding land uses and land values
7. Investigation of the effect of the stormwater
pollution control and pollution control facilities
on floodplain and stream channel ecology, both
upstream and downstream
8. Investigation of the effect of the stormwater
pollution control and pollution control facilities
11
-------
on flood plain utilization
Procedures
At the downstream terminus of the demonstration watershed, a lake was
constructed to act as a combination sediment trap and stormwater man-
agement device. The lake was impounded by constructing an earth-fill
dam with an impervious clay core across the main stream channel. Some
shaping was then done to the stream valley bottom and sides to obtain
the finished pond configuration.
During the course of this demonstration project, the hydraulic performance
characteristics of the pond were monitored with respect to efficiency as a
stormwater management device. Stream gaging and sampling stations
monitored the water quantity and quality entering and leaving the pond.
Cross sections of the pond bottom were surveyed quarterly. Operating
records of the drawdown device valve openings and closings were kept
in order to attempt an analysis of the effect of operating procedure on the
pond's efficiency as a stormwater management device. In addition, the
quarterly airphoto coverage kept track of the changes to the surface
characteristics of the pond area and its watershed.
Methods for the treatment of the stormwater before its release from the
pond were investigated. The purpose of this was to determine if a water
quality significantly higher than would normally be released from the
pond could be economically achieved. If the preliminary analyses indi-
cated that such a feasibility existed, the selected treatment system(s)
would be demonstrated. It was found, however, that, because of the rela-
tively high natural trap efficiency of the pond, additional treatment
methods or devices would not economically increase the water quality of
12
-------
the pond outflow water.
In conjunction with the stormwater aspects of this demonstration program,
a survey of the residents of the Village of Long Reach was conducted.
Generally, the survey was designed to gather opinions and suggestions in
three major areas. First, suggestions were requested as to how the resi-
dents would like to see the area adjacent to the lake and the floodplain
upstream developed for recreation. Secondly, the residents were asked
how they were currently utilizing the lake and floodplain areas (the con-
struction activities had not been completed and only minor recreation
development had been accomplished) . The third major interest was con-
cerned with the basic desirability of a four-acre pond and the effect of
this pond on real estate, aesthetic,and recreational values.
Results and Conclusions
It was found that the type of design used for the dam and retention pond
was adequate from a stormwater management and sediment trap point of
view. In addition, its presence in the development was readily accepted
by the residents. This acceptance is especially apparent if such ponds
can be converted to aesthetically acceptable and harmonious use after con-
struction is complete.
Based on limited observations, the actual trap efficiency of the pond dur-
ing selected storm overflow conditions was found to be generally higher
than predicted on a theoretical basis. Also, under base flow conditions,
little difference in the water quality between the pond influent and effluent
was noted.
13
-------
SEDIMENT HANDLING, DRYING, CONDITIONING, AND DISPOSAL
Objectives
One of the most important aspects of stormwater control is the handling
and ultimate disposal of accumulated sediment. The most efficient sedi-
ment retention system can be rendered useless if the collected sediment is
merely transferred to another area in such a manner as to allow its reentry
into surface waters. Sediment handling and disposal is difficult and cost-
ly. Sediment, as such, has little economic value, so that there is con-
siderable incentive for the employment of low cost yet effective disposal
techniques.
The objectives of this phase of the study were:
1. Evaluation and demonstration of various means of
removing sediment from each of the sediment
collection systems.
2. Evaluation and demonstration of techniques for
transporting wet sediment from the collection
systems to the drying facility.
3. Evaluation and demonstration of techniques for
conditioning sediment prior to application to
drying beds.
14. Evaluation and demonstration of methods for
efficient drying of sediment.
-------
5. Evaluation and demonstration of methods of ultimate
disposal of sediment, including organic and inorganic
additives to alter sediment properties.
Procedures
The primary facility for entrapping sediment from stormwater runoff in
the project watershed was the stormwater retention pond. In order to
reduce the quantity of sediment being transported into the pond and to
help facilitate sediment removal, an engineered forebay was designed and
constructed. In essence, an engineered forebay is a settling basin loca-
ted at the junction of a stream with a pond and separated from the pond
proper by a submersed weir or dam. A forebay serves as an entrapment
device for both bed load and suspended sediments.
The techniques finally selected for demonstrating sediment removal were
conventional dragline, underwater scoop with a long reach, and utilization
of the forebay as a sediment holding and dewatering area prior to hauling
away by conventional dump truck. After sediments from the forebay had
been removed, the drag line bucket was replaced with the long reach
sediment scoop arrangement. Sediment from the pond was then scooped
into the forebay and loaded by backhoe onto dump trucks. The arrange-
ment of scooping sediment into the forebay and simultaneous removal from
the forebay and loading by backhoe resulted in the most efficient sediment
removal technique that was demonstrated.
Several methods were considered for effective drying of sediment. These
included the use of both chemical and physical methods to enhance the
rate of drainage and drying. A wide variety of chemical conditioners
were tested under laboratory conditions for their effect on sediment
15
-------
drainability. The test results indicated that, in general, chemical condi-
tioners would be impractical under field conditions. Physical methods of
sediment dewatering proved to be reasonably effective and practical. The
physical techniques investigated included the use of the forebay as a par-
tial draining device during pond cleaning, sand drying beds, grass filter
strips, and surface scarification of disposed sediment to enhance drying.
Field studies were conducted to determine the feasibility of manipulating
sediment in order to acquire a material with improved characteristics.
Several low cost and usually available materials were tested for their
effectiveness as sediment conditioners. These included digested sewage
sludge, fly ash, woodchips, high magnesium lime, and 10-10-10 fertilizer.
Results and Conclusions
Overall, the selected sediment removal techniques proved an effective
way of cleaning the pond and forebay. However, the drag line opera-
tion proved to be somewhat time-consuming and inefficient because the
bucket frequently spilled sediment material before it could be loaded.
During the sediment conditioning experiments, the following general
observations were noted:
1. Grass seed germination occurred first on plots con-
taining digested sewage treatment plant sludge.
2. Plots containing fly ash germinated two weeks
later than control plots.
3. Areas containing woodchips had stunted and sparse
grass growth.
16
-------
4. Grass coverage and density was greatest on
the fertilizer and sewage sludge plots.
5. Plant response on plots treated with lime
was similar to the control plots.
6. Plots treated with lime experienced dense
rapid grass growth during the first few
weeks. Signs of nutrient deficiency became
apparent during the second month of growth.
HYDROLOGY, WATER QUALITY & ECOLOGY
Objectives
The investigations conducted under this part of the demonstration pro-
gram can be divided into four general categories:
1. Hydrology and water quality of urbanizing areas.
2. Stream channel morphology studies.
3. Application of the EPA Storm Water Management
Model.
4. Monitoring of the changes in the ecology of the
stream channel and floodplain which were asso-
ciated with urbanization.
Within these four major categories, the detailed objectives were as
17
-------
follows:
1. Measurement and recording of hydrologic events,
including rainfall at three raingage stations and
streamflow at four stream gages.
2. Operation of a comprehensive water quality moni-
toring program covering all portions of the demon-
stration watershed as well as at least one down-
stream sampling point.
3. Observation of physical and ecological changes in
floodplains and stream channels as a result of ur-
banization and of erosion control and stormwater
quality control.
4. Maintenance, through aerial photography and other
methods, of a detailed inventory of land use and
watershed activities through the period of the demon-
stration project.
5. Acquisition of a periodic inventory of the fauna
and flora within the stream channel, floodplain,
and pond environs as the area went from rural
to urban in nature.
Procedures
The established gaging and sampling stations were utilized to study the
changes in the surface water hydrology and water quality brought about
18
-------
as a watershed goes from a completely natural state to a fully developed
urban area. The extent of urbanization was recorded by aerial photog-
raphy, hand-held camera photography, and field observations. A total
of twelve months of gaging and sampling records were acquired during
the life of this project.
Bench marks were established, and initial cross sections were surveyed
at eight locations along the main stream channel of the demonstration
watershed and at five places along the pond bottom. These initial cross
sections were completed at a time which corresponded roughly to the
completion of rough grading of the major roads, but when no other devel-
opment had occurred in the watershed. The sections were resurveyed on
a quarterly basis to determine what changes, if any, occurred in the
channel configuration during the various phases of construction.
Data was compiled from the gaging records for input to the EPA Storm
Water Management Model computer program. The Model is basically a
tool developed to aid in predicting the amount of runoff and pollutants
delivered from a watershed from given rainfall events in a completely
urban area. During the course of this project, three major and a num-
ber of minor runs of the Model were completed. However, because of
the low degree of urbanization prevalent in the demonstration project
watershed throughout the project and the discontinuous storm sewer sys-
tem, the applicability of the Model could not be fully tested.
The changes in the ecology of the stream channel, floodplain, and pond
associated with urbanization were monitored. Observations were made of
the physical appearance and any noticeable changes were recorded. A
total of five surveys were conducted in the watershed over a period of
two and one-half years. Changes in or loss of arboreal species, vegeta-
tive cover, and aquatic species were noted.
19
-------
Results and Conclusions
Over the term of the demonstration period, the following base flow water
quality observations were made from the water quality sampling program
as the area went from rural to urban:
1. Turbidity and suspended solids increased.
2. Alkalinity, hardness, and chloride remained
about the same.
3. Nitrite, nitrate, and total phosphate concentra-
tions in the surface waters increased significantly.
During the hydrology studies, a comparison was made between two gaged
subwatersheds within the larger demonstration watershed. Table 1 pre-
sents some of the pertinent characteristics of these two subwatersheds.
From the hydrology studies, the following conclusions were drawn:
1. Throughout the term of the demonstration project
the experimental subwatershed generally produced
less storm runoff per unit area than the reference
subwatershed.
2. Smaller runoff events generally produce a greater
difference in runoff per unit area between the two
subwatersheds than do larger runoff events, although
exceptions do occur as in any natural system.
20
-------
TABLE 1. REFERENCE AND EXPERIMENTAL SUBWATERSHED CHARACTERISTICS
Is)
Characteristic
Natural ground
cover
Storm sewers
Development
Average slope
of ground
Reference Subwatershed
Description
60% open field, 40%
wooded
Storm sewers empty into
natural stream channel.
Medium and low density
housing. Approximately
20% of area devoted to
school site, including
parking lot.
Approximately 4%
Experimental Subwatershed
Description
95% wooded, 5% open field
No natural stream channels,
completely storm sewered.
All low density housing.
Approximately 4%
-------
3. As development progressed in the two subwatersheds,
less of a difference in the runoff yields between the
two subwatersheds resulted.
In the area of stream channel morphology, it was noted that the overall
long-term trend was one of channel downcutting in the upper reaches of
the stream and deposition or aggradation in the lower reaches. The con-
tinued cutting of the outside banks and deposition at the toe of meanders
was also observed, as was general channel widening due to increased
runoff.
The lotic environment of the stream was all but destroyed. Its' condition
was due almost entirely to a lack of stability, with accompanying heavy
sedimentation and abrasive particle transport; loss of pools and protec-
tive cover left little chance of natural recovery by former populations.
It was determined that stream channel recovery might be possible, in
part, if:
1. The stream banks are stabilized with vegetation.
2. Pools are reestablished.
3. Sediment transport is greatly reduced.
4. The stream bottom is stabilized.
5. Runoff containing organic compounds is
strictly controlled.
6. Stormwater management practices are imple-
mented to reduce the volume of periodic surges.
22
-------
7. Base flow during dry periods can be maintained.
The lentic environment of the pond, although severely affected at times,
gave the impression of an ecosystem showing rapid trends toward a
natural succession of life-forms.
23
-------
SECTION V
PROGRAMMED DEMONSTRATION FOR EROSION AND
SEDIMENT CONTROL SPECIALISTS
BACKGROUND
This project, the "Programmed Demonstration for Erosion and Sediment Con-
trol Specialists," was performed under an Environmental Protection Agency
demonstration grant,Project No. S800854 (15030 FMZ) to the Water Resources
Administration, State of Maryland. Hittman Associates, Inc., Columbia,
Maryland was the prime contractor.
The purpose of the project was to develop a series of presentations on sedi-
ment and erosion control and a certification plan for erosion and sediment
control specialists, utilizing technology developed on EPA Grant No. 15030FMZ
(Joint Construction Sediment Control Project), and to demonstrate its worka-
bility. This involved the development of 15 presentations on various topics
relating to erosion and sediment control, the conversion of six of these presen-
tations into the audiovisual format, the demonstration of the program, and the
evaluation of the audiovisual approach against the conventional technical pre-
sentations with slides.
Although the demonstration program was developed for the State of Maryland,
it was anticipated that there would be a nationwide need for such a program.
Accordingly, it leans heavily towards general philosophy and universally
applicable principles and practices.
DEVELOPMENT OF PRESENTATIONS
The primary effort of this program was the development of the 15 conventional
24
-------
presentations, complete with visual aids and student handouts, and six audio-
visual programs consisting of film scripts, written scripts, work books, and
instructor's manuals.
This work involved the taking and collection of over 4,000 separate 35-milli-
meter color and black and white photographic slides, the contributions of
several writers, and close coordination with the audiovisual subcontractor for
technical review of program material.
Conventional Presentations
The topics for 15 conventional presentations were selected so as to provide an
integrated program, rather than a series of presentations on random topics
relating to erosion and sediment control. However, each presentation was
written so that it would entirely, or in large part, stand by itself. In setting
up the program the presentations were grouped under three categories - Basic,
Specialized, and General. The breakdown is as follows:
1. Basic Presentations
Presentation No. 1 - Goal, Objectives and Principles of
Erosion and Sediment Control
Presentation No. 2 - Soils
Presentation No. 3 - Climatology, Hydrology and Hydraulics
Presentation No. 4- Rainfall-Runoff Relationships
Presentation No. 5 - Erosion and Sedimentation
25
-------
Presentation No. 6 - Plant Materials
2. Specific Presentations
Presentation No. 7 - Control of Sediment Generated on
Construction Sites
Presentation No. 8 - Control of Runoff During Construction
Presentation No. 10 - Vegetative Soil Stabilization
Presentation No. 12 - Temporary Soil Stabilization
Presentation No. 13 - Prevention of Waterway Erosion
3. General Presentations
Presentation No. 9 - Erosion and Sediment Control Planning
Presentation No. 11 - Wooded Site Development
Presentation No. 14 - Sediment Control Laws and Regulations
for the State of Maryland
Presentation No. 15 - Foreman-Inspector Responsibilities
The "Basic" category treats the introductory and background aspects of
erosion and sediment control and provides the participant with the basic know
ledge to more fully comprehend the "Specialized" presentations. The
"Specialized" category covers the actual techniques for controlling erosion
26
-------
and sedimentation. The "General" category is intended to provide the parti-
cipant with the general knowledge required to implement the total program of
erosion and sediment control and to make him aware of his importance and
function within the control framework.
In addition to the writing of the presentation material, erosion and sediment
control products and practices were demonstrated in Columbia, Maryland for
the purpose of obtaining photographs for use as visual aids.
The desired method of operation in preparing the conventional presentations
was to write the script, complete with recommended visual aids, have it re-
viewed by the Maryland Water Resources Administration, and then to collect
the visual aids and write the student handout. Photography was often per-
formed concurrently with the writing of the script, except during the winter
months when pertinent construction activity had stopped.
The length of the presentations varied depending upon how much information
had to be presented. The lecture time varied from approximately 30 minutes
to about 75 minutes. The number of slides used in the presentations ranged
between 47 and 104. In all, over 1,100 slides were used in the 15 conventional
presentations.
As noted earlier, the materials for each conventional presentation consisted
of a narrator's script, visual aids, and a participant's handout. Each script
contains a content outline and the complete narration of the presentation. To
provide for the synchronization of the visual aids with the narration, reference
was made to the required visual in the script. The visual references were
numbered consecutively and a brief description of the subject matter was pro-
vided.
27
-------
The participant's handouts contained the important information covered in the
narrator's script, grouped under topical headlines.
Audiovisual Presentations
The six audiovisual presentations were prepared by Educational Communications,
Incorporated of Wayne, Pennsylvania with technical assistance from Hittman
Associates and the Maryland Water Resources Administration. The six con-
ventional presentations which were converted into audiovisual presentations
were:
Presentation No. 1 - Coal, Objectives and Principles of
Erosion and Sediment Control
Presentation No. 5 - Erosion and Sedimentation
Presentation No. 7 - Control of Sediment Generated on
Construction Sites
Presentation No. 8 - Control of Runoff During Construction
Presentation No. 10 - Vegetative Soil Stabilization
Presentation No. 15 - Foreman-Inspector Responsibilities
Two criteria were used in selecting the presentations for conversion into the
audiovisual format. First, the presentations were chosen so as to make up a
coherent, abbreviated package that could be used immediately and then later
be integrated into an expanded program, including nearly all of the remaining
presentations not yet converted into the audiovisual format, and any other
28
-------
presentations that may be developed. The second selection criteria was that
all three of the presentation categories be represented, i.e., Basic, Specific,
and General.
The first steps in the development of the audiovisual presentations were to
define the target population, general performance objectives, and terminal
behavior, and to select the audiovisual hardware.
It was decided by The Water Resources Administration, State of Maryland,
that the presentations would be made available to private contractors and
governmental pollution control agencies. The target population within these
two sectors was defined as construction foremen and inspectors. It was assumed
that the personnel within these categories would have completed a high school
education. It was further assumed that the construction foremen were well-
versed in practical procedures for translating engineering designs into struc-
tures on the construction site. The governmental inspectors, on the other
hand, were assumed to have had less construction experience and the inability,
in most cases, to translate engineering designs.
General Performance Objectives
A foreman who studied the audiovisual presentations was expected to acquire
the following abilities:
1. To be able to look at a plan and visualize it functionally
on the site.
2. To be able to schedule the work so measures to prevent
runoff are coordinated with other construction.
29
-------
3. To recognize various control structures on the plan
and transfer these to the site.
4. To understand his role and responsibilities and his
relationship with government inspectors.
5. To determine whether the proposed plan will perform
adequately on the site and be able to go back to the
designer with recommendations for changes, if needed.
A government inspector taking this program was expected to develop the
following abilities:
1. To understand his role and responsibilities.
2. To understand the cross relationship between
himself and the contractors' foreman.
3. To determine if the construction site is in com-
pliance with the plan and if it will effectively
control runoff.
4. To be able to report on the reasons for problems and
make proposals for their correction.
5. To be able to make a decision as to what recommendations
he can make and what changes must go back for redesign
and approval.
30
-------
6. To be able to prepare effective reports concerning each
particular situation.
The terminal behavior determined at the outset of the development of the pre-
sentations was twofold. At the conclusion of each of the audiovisual programs,
trainees would be required to complete a written test. These tests would in-
corporate various forms of questions relating directly to the subject matter
just covered. It was expected that 90 percent of the participants would score
a correct response on 90 percent of the questions. Secondly, as a more long
term requirement of this project, it was expected that participants would gain
increased motivation to perform their assigned tasks efficiently and cooperate
with all those charged with the responsibility of reducing erosion damage.
Audiovisual Hardware
It was decided that the audiovisual equipment should have the following
characteristics:
1. Be able to present filmstrips which are automatically
synchronized to the sound.
2. Have the sound tape and filmstrip enclosed in one
integral cassette.
3. Have the capability of being used as a front screen
projector which could be viewed by groups of approx-
imately 15 persons.
4. Be capable of conversion to a rear screen projector
for individual viewing.
31
-------
5. Be small and compact enough for an individual to
take home.
Each audiovisual presentation was packaged in plastic cassettes containing
both a magnetic tape sound track and a synchronized 16-millimeter film strip.
Each cassette has a running time of approximately 15 to 20 minutes. It is
estimated that the total time required to present each cassette is about 30
minutes. This includes time for workbook exercises and discussions.
Workbooks were also prepared for the audiovisual presentations. These were
designed to serve as an additional reinforcement and as a reference document
that the participant could retain. In addition to containing questions to be
answered at each workbook stop during the program presentation, the work-
books contain a review test and a descriptive outline of the subject matter.
To assist the supervisor in giving the programs, a manual was prepared for
each program. These documents contain information on how to set up the
program and operate the audiovisual machines, list the primary objectives of
the program, provide a listing of suggested discussion topics, and contain the
answers for all of the questions in the participant's workbook.
PROGRAM DEMONSTRATION AND EVALUATION
As part of the program, a demonstration was conducted to evaluate the con-
ventional presentation approach versus the audiovisual approach. As visual-
ized, the conventional approach would use a scientist or engineer with little
or no public speaking experience to narrate a slide show and distribute student
handouts. In nearly all cases, the narration would be read verbatum from the
script. It was further assumed that during the question and answer period
which follows each presentation, some additional information, not found in the
script, may be interjected.
32
-------
The audiovisual approach was assumed to involve the use of an audiovisual
machine and workbook in the presence of a supervisor. His primary function
would be to lead group discussions and answer questions. The ideal audience
for this approach consists of no more than 15 persons.
The demonstration and evaluation was conducted on a typical target audience
consisting of inspectors and construction foremen. Due to the coincidence of
the demonstration and evaluation program with the active construction season,
it was not possible to obtain enough time to demonstrate all of the presentations
and evaluate all six audiovisual programs against their conventional counter-
parts. A total of three audiovisual presentations were used.
Procedure
Government inspectors and contractor's foremen were invited to participate
in the demonstration and evaluation program. A total of 26 men participated.
Each man was given a form prepared by the Water Resources Administration
on which he could record profile information. Each form was numbered con-
secutively from one through twenty-six. Following an introduction and state-
ment of the purpose of the project, the men with odd-numbered forms were
asked to leave the room and go to another location where they were shown the
audiovisual program. Those with even-numbered forms were asked to stay
in the first room and were then given a conventional presentation. Both
groups were equally divided with respect to employment and level of education
During the first period, both groups viewed the presentation on "Goal,
Objectives and Principles of Erosion and Sediment Control". The group with
odd numbers received the information via an audiovisual program and the
group with even numbers received it via a conventional slide-illustrated pre-
33
-------
sentation. In the second period the groups viewed the material on "Erosion
and Sedimentation". Again, the odd numbered group received the audiovisual
version and the even numbered group received the conventional presentation.
Both groups were then given identical evaluation tests. Following the test,
the two groups reversed their roles. That is, the odd numbered group re-
ceived a conventional presentation and the even numbered group received an
audiovisual program. They both were exposed to the same subject. Both
groups were then given a form on which to evaluate the two different methods
of presentation.
Results
The group which received the audiovisual presentation did score higher on
the evaluation test than the group which received the conventional presenta-
tion. However, the difference in test scores was not highly significant.
The evaluation of the presentation by the individuals in the two groups did
present some additional insights. Of the 13 subjects who received the audio-
visual presentation, 11 were favorable toward it, while only eight were favor-
able toward the conventional presentation from the group initially receiving
that presentation. Both groups clearly preferred the audiovisual presentation
over the lecture.
CERTIFICATION PLAN
A requirement of this demonstration program was to develop a plan for the
certification of erosion and sediment control specialists in the State of Maryland
It was decided that the primary thrust of the plan would be to certify the on-
site erosion and sediment control specialists. The word "specialist" is intend-
-------
ed to mean only construction foremen or supervisors. The majority of the
governmental inspectors are not specialists in that they are also responsible
for the inspection of other construction-related functions and pollution sources.
Of course, it was felt that the erosion and sediment control inspector should
not be denied the opportunity to acquire the certification, only that its acqui-
sition not be considered an essential requirement of his job. However, it is
important that the governmental inspector be exposed to the program developed
in this demonstration. It was felt that State and local agencies responsible for
erosion and sediment control will readily and voluntarily utilize the program.
Strong leadership by the state will be an important factor in this regard.
On the other hand, it was felt that many of the private construction contractors
performing grading work will not quickly, nor fully utilize the States' program
unless they are legally required to have a certified specialist in charge of the
implementation of erosion and sediment control plans on their construction
sites. This requirement can be accomplished by an amendment to the existing
Maryland Sediment Control Law and/or Regulations. This amendment would
state to the effect that all contractors performing grading operations shall have
an on-site certified erosion and sediment control specialist to supervise the
impleirentation of the erosion and sediment control plans.
An integral part of a program to certify erosion and sediment control special-
ists would be the dissemination of the materials developed in this demonstra-
tion to the counties, contractors, and educational institutions to help personnel
to become knowledgeable erosion and sediment control specialists.
In that it will take some time to certify these specialists, it was decided that an
interim certification should be initially issued and a time limit set for full cer-
tification. It was recommended that an interim certification be required by
July 1, 1974, at which time the amendment to the Saw and/or regulation would
35
-------
become effective, and that a full certification be required by July 1, 1976.
The minimum requirements for interim certification should be three years
grading or related construction experience, one year of which must be in a
supervisory capacity which includes responsibility for the implementation of
erosion arid sediment control plans. No test would be required, but an appli-
cation would have to be made to the Maryland Department of Natural Resources
and approved by the board and an interim certificate issued to the applicant.
Full certification would require five years of grading or related construction
experience, two years of which must be in a supervisory capacity which in-
cludes responsibility for implementing erosion and sediment control plans.
Up to two of the three years of nonsupervisory experience could be substi-
tuted by job-related, post-high school education. The applicant would have
to apply to the State for the certification and pass a written or oral test on the
subject of erosion and sediment control. The test would be geared to the train-
ing program developed in this demonstration and would be administered two or
more times a year, depending upon demand. The applicant would be allowed
to take an oral exam if he failed the written test at least twice and had taken the
prescribed state training program consisting of the audiovisual presentations.
No limit would be set on the number of times the applicant could take the test.
The program would be administered by a Maryland Board of Erosion and Sedi-
ment Control Specialists, composed of five to seven representative members
appointed by the Secretary of the Maryland Department of Natural Resources.
36
-------
SECTION VI
DEMONSTRATION OF THE SEPARATION AND
DISPOSAL OF CONCENTRATED SEDIMENTS
BACKGROUND
Hittman Associates, Inc., under Contract No. 68-01-0743 to the U. S. Envir-
onmental 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 system which could be set up to process the slurry from the
dredge 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.
After the field demonstration was complete, further experiments were per-
formed on one of the promising pieces of equipment in the processing system.
This equipment item, known as the Uni-Flow filter, is essentially a bag-type
fabric filter. The dirty water is pumped to the inside of fabric hoses and al-
lowed to filter through the hoses. Summary results of both the field demon-
stration and the additional experiments on the Uni-Flow filter are contained
in this section.
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
37
-------
National Car Rental Systems, Inc. A/1UD CAT Division. Figure 2 is an over-
all view of the MUD CAT dredge. It is specially designed for use on small
lakes, and to impart minimum turbidity to the water while dredging. The
dredge moves in straight-line directions by winching itself along a taut,
fixed cable. 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 to 30 percent solids concentration of the slurry.
PROCESSING SYSTEM
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
FIGURE 2. MUD CAT Dredge
38
-------
in the processing system based on the equipment's degree of portability, cost,
expected performance, and the physical characteristics of the dredge spoil.
The portable sediment processing system selected for testing 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 arrangements during the course of dredging operations.
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. Figure 3 is a schematic diagram of the overall sedi-
ment processing and sludge disposal system.
Initial Solids Removal
Two elevated bins, each with an initial capacity of 36 cubic yards were in-
stalled in series as the initial solids removal phase. These storage bins are
of the type used in concrete batch plant operations. The discharge from the
dredge was pumped directly to the first bin where settling of suspended
solids occurred. The slurry was then allowed to overflow into the second
bin where additional settling occurred. From the second bin, the flow was
split to either a temporary holding basin or to a feed pump for the hydrocy-
clones. Figure 4 shows the bins used for the field demonstration.
39
-------
MUD CAT discharge
approx. 1500 pgm
<*.
Initial Separation
Two 36-yard
Elevated Bins
trucking
Bin Solids
Disposal Area
Temporary Holding/
Settling Basin
approx.
500 gpm
Secondary Separation
Hydrocyclones
Final Filtration
Cartridge Filter
Unit
backflush
Final Filtration
Uni-Flow Filter
backflush
backflush
Return Water
to pond
Sludge Disposal
Area
Figure 3. Schematic of Processing and Sludge Disposal System
-------
FIGURE 4. Initial Solids Removal: Elevated Bins
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 immediately 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 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. There-
fore, standard hand-held concrete vibrators were utilized to help fluidize
and drain the sediment into the trucks.
Secondary Separation
A bank of hydrocyclone cones comprised the secondary separation step of
this portable sediment handling system. 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 5 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.
FIGURE 5. Secondary Separation: Hydrocyclones
-------
The commercially-available filter selected for the field trials was of the
cartridge filter type. The unit consisted of four model 16-1 7-51 Crall
filters, each of which contained 51 permanent sand cartridges with filter
openings rated at 25 microns. An on-line automatic backflush cycle was
installed so that one filter unit could be backflushing while the other three
remained on-line. Figure 6 shows this cartridge filter unit.
Basically, the Uni-Flow filter is a system of hollow fabric "soaker" hoses
that present a more or less solid, impermeable barrier to suspended mater-
ial. The dredged slurry is pumped into the center of the hoses, the suspend
ing liquid permeates through the hoses and is collected in a filtrate collector
and is piped away. The loose sludge within each hose is periodically dis-
charged into a sludge collector and is removed from the filter unit.
FIGURE 6. Final Filtration: Cartridge Filter Unit
U3
-------
Previous experiments with the Uni-Flow filter performed by the Aqua-Ion
Corporation under EPA Contract No. 68-01-0043 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. Further ex-
periments were conducted under this program in order to arrive at design
criteria for a prototype unit which would be capable of processing the expec-
ted 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.
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 en-
abled 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 7 shows this prototype Uni-
Flow filter.
TEST SITE
The site selected for the field demonstration was a two-year old, 1.7 acre
pond which was designed and built as a sediment retention basin. The pond
was located in Prince George's County, Maryland. At the time of dredging
the pond was 99 percent filled with sediment.
-------
-.
FIGURE 7. Final Filtration: Uni-Flow Filter
FIELD DEMONSTRATION RESULTS AND CONCLUSIONS
Removal System
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.
The MUD CAT dredge proved very efficient in removing the deposited sed-
iments from the pond bottom and in preventing the resuspension of the sedi-
ments during the dredging operations. 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.
Processing System
Overall, the portable sediment processing system, consisting of two eleva-
ted 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 unloading on the hydro-
cyclones was found to be not economically justified in a portable sediment
processing system. In addition, it was concluded that the use of hydrocy-
clones for dredged spoil processing should be limited to removing sand size,
i .e., 74 microns or larger particles. The majority of the suspended solids
in the slurry fed to the hydrocyclones during the field demonstration were
smaller than sand size.
The usefulness of the cartridge filter unit in the processing system was mar-
ginal. Operating and maintenance restrictions would probably preclude the
widespread utilization of such units for processing dredged 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 re-
turn water can be produced through use of a portable sediment processing
system.
ADDITIONAL TESTS: LARGE DIAMETER FABRIC FILTER HOSES
Procedure
Fabric filter hoses of greater than one inch in diameter were tested and
evaluated on a separate test stand after the field demonstration of the por-
table sediment processing system was completed. In particular, larger
diameter filters were investigated for their ability to resist blocking with
sediment, the chief 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 sur-
face area.
2. Pressure handling ability.
3. Tendency of the filter tubes to bow with increased
pressures.
4. Quality of the effluent.
5. Total effluent flow.
6. Filtration cycle time (time between backflushes) .
-------
7. Ease of cleaning during a normal backflush (sludge
draining) cycle.
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.
Testing was performed in two phases. In the first phase, four different
fabric filter materials were subjected to various tests, and the results of the
tests were compared to determine the fabric material which exhibited the
best performance characteristics in terms of the seven handling character-
istics described above. At the conclusion of the first phase tests it was evi-
dent that a multifilament polypropylene fabric performed the best, both in
terms of the effluent quality and the average flow rate through the hose.
The primary goal of the second phase of the 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 requirements of any full scale prototype as much as possible.
Consequently, the following parameters were varied during the second
phase of testing:
1. Type of backflushing operations
2. Presence of wire mesh cylinder inside filter column
48
-------
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
Results and Conclusions
Overall, the five-inch diameter polypropylene hoses tested performed
better than the one-inch hoses utilized on the Uni-Flow filter during the
field demonstration. Further utilization of the one-inch diameter hoses
for wet filtration was thus abandoned.
It was determined that five-inch diameter, 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
nose yielded comparable effluent qualitites and throughflow rates and
required less hardware than the other hoses.
It was recommended that further tests be performed on the applicability of
the five-inch diameter Uni-Flow hoses to the filtering of other types of
wastes and pollutants. Based on limited tests, these hoses showed promise
for application to other wet bag filtration areas.
-------
SECTION VII
REFERENCES
1. State of Maryland Department of Water Resources, and Becker, B. C.,
T. R. Mills. Guidelines for Erosion and Sediment Control Planning
and Implementation. Hittman Associates, Inc. and State of Maryland
Department of Water Resources for U.S. Environmental Protection
Agency- Washington, D. C. Report No. EPA-R2-72-015. August 1972.
228p.
2. Metcalf & Eddy, Inc., University of Florida, and Water Resources
Engineers, Inc. Storm Water Management Model, 4vols. U. S. Envir-
onmental Protection Agency. Washington, D. C. Report Nos. 11024 DOC
07/71, July 1971; 11024 DOC 08/71, August 1971; 11024 DOC 09/71,
September 1971; and 11024 DOC 10/71, October 1971.
50
-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
1. Repo'tttfo.
w
An Executive Summary of Three EPA Demonstration
Programs in Erosion and Sediment Control
7, Authvt(s)
Nawrocki, Michael A., and Sitek, Gary M.
Organization
Hittman Associates, Inc.
10 PtojcctNo.
PE 1B2042
II. Contract/ Grant No.
68-01-0743
Environmental Protection Agency report No. EPA-660/2-74-073, June 1974
16. Abstract
This report presents the highlights of three recently completed programs in the area
of sediment and erosion control. These programs were a "Joint Construction Sediment
Control Project," Project No. 15030 FMZ; a "Programmed Demonstration for Erosion and
Sediment Control Specialists," Project No. S800854 (15030 FMZ); and a "Demonstration
of the Separation and Disposal of Concentrated Sediments," Contract No. 68-01-0743.
The first program demonstrated and developed guidelines for erosion and sediment
control in urbanizing areas, the second produced a series of 15 presentations on sediment)
and erosion control, and the third program consisted of a field demonstration of a system
for removing and processing sediments from pond bottoms.
a.
*Aquatic Environment, Construction, *Demonstration Watersheds,
*Erosion Control, *Rainfall-Runoff Relationship, *Sedimentation, Urbanization,
*Watershed, *Dredging, *Sediment Deposition, *Filtering Systems, *Separation Tech-
niques, Biology, Channel Morphology
17b. Identifiers
"Guidelines', *Columbia, Maryland, *Presentations, *Suspended solids
separation. Pond dredging. Grade control
/7c. COWRRField & Group Q2E, 02H, 02J, 04A, OQC, 040, 05C, 05D, 05C
18. Availability
"•"BB««i8PW*i**!PSlfl
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 2O24O
Abstractor
Michael A. Nawrocki | Institution Hittman Ascnriafc
WRSIC IO2 (REV JUNE 1971)
------- |