M AD-A280 911

US Army Corps

of Engineers

Water Resources

Support Center

Management of Bottom Sediments

Containing Toxic Substances

Proceedings of the 15th U.S./Japan

Experts Meeting

Thomas R. Patin, Editor

DTIC

S ELECTE

JUN 2 91994D

94-19797

May 1994 94 6 28 149
The contents of this report are not to be used for advertising,

publication, or promotional purposes. Citation of trade names

does not constitute an official endorsement or approval of the use

of such commercial products.

O i F3MTIM ON RIECYCD PAPME
Management of Bottom Sediments

Containing Toxic Substances

Proceedings of the 15th U.S./Japan

Experts Meeting

Thomas R. Patin, Editor

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U.S./Japan Experts Meeting on the Management of Bottom Sediments

Containing Toxic Substances (15th" 1991 : San Pedro, Califoria) Management of bottom sediments containing toxic substances : proceedings of the 15th U.S./Japan Experts Meeting / Thomas R. Patin,

editor.

345 p. : ill. ; 28 cm. - (Technical report ; -94-)

Includes bibliographical references.

1. Marine sediments -- Environmental aspects - Congresses.

2. Dredging spoil - Congresses. 3. Dredging -- Environmental aspects -- Congresses. 1. Patin, Thomas R. 11. Water Resources Support Center (U.S.) 11. U.S. Army Engineer Waterways Experiment

Station. Ill. Title.

GC380 M35 1991
PREFACE

The 15th U.S./Japan Experts Meeting on Management of Bottom Sediments

Containing Toxic Substances was held 19-21 November 1991 in San Pedro, California. The meeting is held annually through an agreement with the U.S. Army

Corps of Engineers and the Japan Ministry of Transport to provide a forum for

presentation of papers and in-depth discussions on dredging and disposal of

contaminated sediment.

Mr. Jimmy Bates, Chief, Policy and Planning Division, Headquarters,

U.S. Army Corps of Engineers, was the U.S. Chairman. Mr. Yasuhiro Kawashima,

Director, Environment Division, Ports and Harbors Bureau, Ministry of Transport, was the Japanese Chairman.

Coordinator of the organizational activities was Mr. Paul Rub.

U.S. Technical Topic organizer and editor of this report was Mr. Thomas R.

Patin, program manager, Dredging Operations Technical Support Program (DOTS),

U.S. Army Engineer Waterways Experiment Station (WES), Vicksburg, Miss.

Acceslon For

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CONTENTS

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

DELEGATES ........................ ............................... iv

AGENDA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

JOINT COMMUNIQUE . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

OVERVIEW OF US DREDGING PROGRAM by Jimmy F. Bates .......... ........... 1

THE CHALLENGE OF AN EFFECTIVE MARRIAGE OF GOOD SCIENCE AND

GOOD POLICY by D. G. Lee ............... ....................... 2

IMPROVEMENT OF WATER AND BOTTOM SEDIMENT QUALITY IN THE

OSAKA PORT AREA BY REMOVAL OF ACCUMULATED ORGANIC SLUDGE

by T. Nakano .................... ............................. 7

TECHNOLOGIES FOR REMEDIATION OF CONTAMINATED SEDIMENTS IN THE

GREAT LAKES by N. R. Francingues, Jr., and D. E. Averett ...... 26

DEVELOPMENT OF A LEACHING PROTOCOL FOR EVALUATING GROUND

WATER IMPACT FROM CONTAMINATED SEDIMENT by J. M. Brannon

and T. E. Myers ................. ........................... ... 32

PREDICTION OF SURPLUS WATER DENSITY AT RECLAMATION SITE

by T. Maekawa .................... ............................ .. 53

A SUMMARY OF RECENT CAPPING INVESTIGATIONS WITH DREDGED

SEDIMENTS IN NEW ENGLAND by T. Fredette ........ ............... .. 86

THE DEVELOPMENT OF A CLEAN AND DENSE DREDGING SYSTEM

by A. Teramoto and S. Ikeda ........... ..................... .. 98

PHYSICAL SEPARATION TECHNIQUES FOR CONTAMINATED SEDIMENT

by J. P. Allen and I. G. Torres .......... ................... .. 121

INTRODUCTION OF NEW METHOD OF DISPOSING DREDGED MUDDY SOIL

WITHOUT DISTURBING MARINE ENVIRONMENT by H. Sakamoto,

T. Fujisaku, M. Shimoda, and K. Ishiguro ....... .............. 131

RESTORATION OF LAKES AND MARSHES TO APPLY THE TREATMENT

OF BOTTOM SEDIMENTS USING BIO-REACTORS (BIOTECHNOLOGY)

by T. Matsuno, T. Oowada, H. Kishi, and M. Natori ... .......... .. 152

PCB VOLATILIZATION FROM DREDGED MATERIAL, INDIANA HARBOR, INDIANA . . . 173

SEA BLUE PLAN: A CASE STUDY ON PORT OF AMAGASAKI-NISHINOMIYAASHIYA by H. Hamabata, Y. Suda, and H. Sugimoto ... ........... .. 183

ii
SEA BLUE PLAN: EXPERIMENT OF SEA WATER PURIFICATION BY

POROUS BED CONTACT PURIFICATION METHOD by Y. Suda,

H. Hamabata, and Y. Hosokawa ............ .................... .. 208

STABILIZING METHOD BY SOLIDIFICATION FOR DREDGED BOTTOM

SEDIMENTS by N. Wadas ................ ........................ ... 251

SOLIDIFICATION/STABILIZATION TECHNOLOGY FOR REDUCING THE MOBILITY

OF HEAVY METALS IN POLLUTED SEDIMENTS by T. E. Myers,

D. E. Averett, E. C. Fleming, and M. G. Channel ... ........... ... 273

REFORMING TEST ON DREDGED SEDIMENT WITH POLYMER SOLIDIFYING

AGENT AND A STUDY OF ITS EFFECTIVENESS by K. Nikaido. .......... ... 282

BENCH-SCALE TESTS OF INNOVATIVE TREATMENT TECHNOLOGIES ON

SEDIMENTS FROM GREAT LAKES, RIVERS, AND HARBORS

by S. Garbaciak ................. ........................... .... 315

ORIGIN AND TRANSPORTATION OF AIR-BORN MICRO-POLLUTANTS INTO

BOTTOM SEDIMENTS IN AN URBAN RIVER by M. Okada, Y. Kurimoto,

K. Yoshida, and T. Kotake ............... ...................... ... 318

QUESTIONS AND ANSWERS ................. ......................... ... 329

Iiii
DELEGATES

15TH U.S./JAPAN EXPERTS MEETING ON MANAGEMENT

OF BOTTOM SEDIMENTS CONTAINING

TOXIC SUBSTANCES

Japanese Delegation

Yasuhiro Kawashima Director, Environment Division,

Co-chairman Ports and Harbors Bureau,

Ministry of Transport

Taizo Nakano Port Development Department,

Comprehensive Planning Division,

Port and Harbor Bureau, Osaka City

Takeo Maekawa Japan Dredging and Reclamation

Engineering Association

Akira Teramoto Japan Sediments Management

Association

Hiroyuki Sakamoto Japan Sediments Management

Association

Makoto Natori Supervisor, Experiment Group of

Rikuzen Takata City

Hideo Hamabata Japan Sediments Management

Association

Yusuke Suda Japan Sediments Management

Association

Nobuaki Wada Japan Sediments Management

Association

Kiyoshi Nikaido Japan Sediments Management

Associarion

Mitsumasa Okado Laboratory of Environmental

Chemistry, Hiroshima University

U.S. Delegation

Jimmy F. Bates Chief, Policy and Planning Division,

Co-chairman Headquarters, U.S. Army Corps of

Engineers

Dwayne G. Lee Port of Los Angeles

iv
Norman R. Francingues, Jr. U.S. Army Engineer Waterways

Experiment Station

James Brannon U.S. Army Engineer Waterways

Experiment Station

Thomas Fredette U.S. Army Corps of Engineers,

New England Division

James Allen U.S. Bureau of Mines

Jay Semmler U.S. Army Corps of Engineers,

Chicago District

Thomas Myers U.S. Army Engineer Waterways

Experiment Station

Steve Garbaciak U.S. Environmental Protection

Agency

v
AGENDA

15TH U.S./JAPAN EXPERTS MEETING ON MANAGEMENT

OF BOTTOM SEDIMENTS CONTAINING

TOXIC SUBSTANCES

San Pedro, California

19-21 November 1991

Co-Chairman

Mr. Yasuhiro Kawashima

Director, Environment Division

Ports and Harbors Bureau, Ministry of Transport

Mr. Jimmy Bates

Chief, Policy and Planning Division

Headquarters, U.S. Army Corps of Engineers

Monday. November 18, 1991

7:00-8:00 p.m. Meeting of the Co-Chairmen at the Sheraton

Los Angeles Harbor

Tuesday. November 19, 1991

8:00-8:30 a.m. Arrival at Port of Los Angeles Administrative Building

- Conference registrants package available

8:30-9:00 a.m. Opening remarks: Mr. Yasuhiro Kawashima

Opening remarks and introduction of Keynote Speaker:

Mr. Jimmy Bates

9:00-9:30 a.m. Keynote address by Dr. Tudor Davies, Director, Office

of Science and Technology, U.S. Environmental

Protection Agency, Washington, DC

9:30-9:45 a.m. BREAK

9:45-10:25 a.m. Mr. Dwayne G. Lee, "The Challenge of an Effective

Marriage of Good Science and Good Policy"

10:25-11:05 a.m. Mr. Taizo Nakano, "Improvements of Water and Bottom

Sediment Quality in the Osaka Port Area by Removal

of Accumulated Organic Sludge"

11:05-11:45 a.m. Mr. Norman R. Francingues, Jr., "Technologies for

Remediation of Contaminated Sediments in the Great

Lakes"

vi
11:45-12:00 a.m. Transfer to Port of Los Angeles dock for afternoon

tour

12:00-3:00 p.m. Lunch and tour of the Ports of Los Angeles and

Long Beach hosted by the Port of Long Beach

6:00-8:00 p.m. Welcome reception hosted by the Port of Los Angeles at

the Port of Los Angeles Administrative Building

Wednesday. November 20. 1991

8:00-8:40 a.m. Dr. James M. Brannon, "Development of a Leaching

Protocol for Evaluating Ground Water Impact From

Contaminated Sediment"

8:40-9:20 a.m. Mr. Takeo Maekawa, "Prediction of Surplus Water

Density at Reclamation Site"

9:20-10:00 a.m. Dr. Thomas Fredette, "A Summary of Recent Capping

Investigations with Dredged Sediments in

New England"

10:00-10:15 a.m. BREAK

10:15-10:55 a.m. Mr. Akira Teramoto, "The Development of a Ciean and

Dense Dredging System"

10:55-11:35 a.m. Dr. James Allen, "Physical Separation Techniques for

Contaminated Sediments"

11:35-12:15 p.m. Mr. Hiroyuki Sakamoto, "Introduction of New Method of

Disposing Dredged Muddy Soil Without Disturbing

Marine Environment"

12:15-12:30 p.m. Return to Sheraton Los Angeles Harbor Hotel

12:30-1:30 p.m. Luncheon sponsored by the Western Dredging

Association, National Association of Dredging

Contractors, and Dredging Contractors Association of

California

1:45-2:25 p.m. Mr. Makoto Natori, "Restoration of Lakes and Marshes

to Apply the Treatment of Bottom Sediments Using

Bio-Reactors (Biotechnology)"

2:25-3:05 p.m. Dr. James Brannon, "Assessing Volatile Organics From

Highly Contaminated Sediments in Confined Disposal

Areas"

3:05-3:15 p.m. BREAK

3:15-4:00 p.m. Mr. Hideo Hamabata, "Sea Blue Plan: A Case Study on

the Port of Amagasaki-Nishinomiya-Ashiya"

vii
4:00-4:40 p.m. Mr. Yusuke Suda, "Sea Blue Plan: Experiment of Sea

Water Purification by Porous Bed Contact

Purification Method"

7:00-9:00 p.m. Evening reception hosted by the Government of Japan

Thursday. November 21. 1991

8:30-9:10 a.m. Mr. Nobuaki Wada, "Stabilizing Method by

Solidification for Dredged Bottom Sediments"

9:10-9:50 a.m. Mr. Thomas Myers, "Solidification/Stabilization

Technology for Reducing the Mobility of Heavy Metals

in Polluted Sediments"

9:50-10:05 a.m. BREAK

10:05-10:45 a.m. Mr. Kiyoshi Nikaido, "Reforming Test on Dredged

Sediment With Polymer Solidifying Agent and a Study

of its Effectiveness"

10:45-11:25 a.m. Mr. Steve Garbaciak, "Bench-Scale Evaluation for

Contaminated Sediments in the Great Lakes"

11:30-12:30 p.m. LUNCH

12:45-1:25 p.m. Dr. Mitsumasa Okada, "Origin and Transportation of

Air-Born Micropollutants into Bottom Sediments in an

Urban River"

1:30-2:30 p.m. Closing remarks by Japanese and United States

Co-Chairmen

viii
OVERVIEW OF US DREDGING PROGRAM

Jimmy F. Bates

Chief, Policy and Planning Division

Directorate of Civil Works

US Army Corps of Engineers

Washington, DC

As a brief introduction to the US technical papers, the focus in this

country in terms of contaminated bottor. sediments is still on problem identification, technology development (pilot field and laboratory studies, benchscale modeling, and demonstrations), and predictive testing and related impact

assessment methodologies.

With but few exceptions (i.e. capping), the implementation of actual

remediation projects, while a reality for upland contamination problems for

some years now, still awaits a better national definition of the scope and

magnitude of the problem and, of course, adequate and appropriate funding

sources. We do, however, anticipate a very significant project management

need in future years in this area.

Examples of major accomplishments since our last meeting are:

"* Pilot demonstration of clean-up technologies at New Bedford Harbor

(Superfund Site). A number of technical reports on various aspects

of that initiative are now available.

"* Significant advances in developing innovative technologies and

problem identification for contaminated sediments in the Great Lakes.

" The Corps of Engineers and the USEPA are in the midst of a broad

initiative to revise and update our contaminant testing procedures

for dredged sediments. Revised testing procedures for the ocean

disposal program were published in the spring of 1991. A major joint

initiative with EPA is now under way to appropriately revise our

testing procedures for inland waters.
CHALLENGE OF AN EFFECTIVE MARRIAGE

OF GOOD SCIENCE AND GOOD POLICY

Dwayne G. Lee

Port of Los Angeles

P. 0. Box 151, San Pedro, CA 90733-0151

ABSTRACT

In resolving a dredged disposal problem, good science

and good policy are responding to different concerns

and frequently their respective responses will conflict. A current case study demonstrating these conflicts is the on-going debate over the meaning of the

term "precautionary principle" as it applies to

dredging and dredged disposal. This debate clearly

highlights the science-policy dichotomy. While a comprehensive discussion of resolution of these conflicts

is not attempted, some general observations can be

made.

INTRODUCIION

Good morning, it is a pleasure for me to be here today. Let me say how

delighted we are at the Port of Los Angeles to be one of your hosts for this

meeting. My name is Dwayne Lee, and I am the Deputy Executive Director of

Development for the Port of Los Angeles. I also serve as the Chairman of the

Dredging Task Force for the International Association of Ports and Harbors and

represent them at the London Dumping Convention. It is in that capacity that

I am primarily associated with dredging issues from a policy perspective. The

views that I will express today are my own and do not necessarily reflect the

view of either the Port of Los Angeles or the International Association of

Ports and Harbors.

TEXT

What I would like to share with you today is my understanding and definition of a problem; provide you with a case study of a current issue working

in the international arena that serves as an excellent example of this challenge of marrying good science with good policy; and conclude with some general observations. My discussion will definitely not be a comprehensive

treatment of this subject. It is intended to be a thought-piece to provide a

few ideas and stimulate additional thinking.

What is the problem as I see and understand it? First, let me talk

about good science. Good science, in my judgement, is the responsibility of

the scientist and the engineer. Although there is a difference between the

role of the scientist and the role of the engineer, in my discussion I incorporate both of those responsibilities under the term "good science". Given

the physical manifestations of nature or some natural process, science

2
attempts to find answers to certain questions. Typical questions would

include a determination of:

A. What do we know and what do we not know?

k. For those things that we do not know, what is the risk associated

with the absence of that information?

c. What is the interrelationship of all of the physical variables associated with this natural process which I, the scientist, am

investigating?

d. What are the forcing functions? What processes in nature are driving the physical phenomena that is being witnessed and experienced?

e. What are the cause and effect relationships among those variables

that produce the necessary results?

Once the scientist has answered these questions, the results are passed

to the engineer who then seeks to merge together all of the knowns to make

some reasonable prudent assumptions about the unknowns and then seek the technique or process which will produce a solution yielding a desired result.

Normally, that result will be some physical modification of an existing system. If you treat this whole endeavor by both the scientist and the engineer

as some intellectual process, generally it must be repeated with each iteration producing an incrementally more effective solution than the last until

some acceptable level of optimization is reached. That is my understanding

and my definition of "good science".

Good policy, on the other hand, is the responsibility of the manager and

the politician. Given the social-economic interactions among people, the

policymaker attempts to answer a different set of questions similar to the

following:

a. Which solutions will be acceptable to the political constituencies

that are impacted and affected by this particular policy?

k. What is the cost effective solution to the business units involved?

c. And, perhaps most importantly, what is politically achievable?

Given the political climate in which I now work and function and

given the nature of this particular problem, politically what is the

most I can expect to achieve and accomplish?

It has been my observation that the questions posed and answered by the

scientist and engineer, when compared to the questions posed and answered by

the manager and policymaker, often conflict with each other and thereby create

a dynamic tension. The problem, therefore, is to find a good way to reconcile

the differences in the conflicts.

A current case study that I am familiar with, that is working as we

speak in the international dredging arena, has to do with an acceptable definition of the term "the precautionary principle." First, let me provide a

definition of international environmental organizations, such as Greenpeace or

3
Friends of the Earth International. Friends of the Earth International has

the following definition for "the precautionary principle":

"The precautionary principle comprises the idea that no substance

may be discharged into the marine environment as long as there

exists uncertainties about the impact on the environment even if

there is no scientific proof of possible harmful effects of these

substances."

The definition as posed by Friends of the Earth needs to be taken in

context of their particular agenda in the international dredging community.

They are very open and up front in stating this as their particular goal.

They are promoting industrial production technologies which are clean production systems, and I believe they would define clean as 100% so that, in

effect, the industrial processes throughout the world that produce effluent or

outflows would be such that the production process is 100% clean. Second,

their desire is that there be no discharge of any man-made material or processes into the ocean waters. Finally, they desire, through this definition

and approach of the precautionary principle, to shift the burden of proof for

permitting a dredge disposal project. Currently, once an applicant demonstrates that no significant environmental damage will result from a dredged

disposal project, his project is permitted to proceed. Some level of environmental impact is accepted and some areas where pos 1⁄2t impacts cannot be

scientifically established by a cause-and-effect rel oionship are not considered. At this point, an opponent to the project has the burden of proof to

show, by scientific arguments, that significant environmental impacts do

result from the project. Friends of the Earth would propose to shift that

burden to the project sponsor who must now prove up front that there is no

environmental damage nor uncertainty of any environmental damage. Even if

there is no scientific proof of possible harmful effects, in the Friends of

the Earth view, dredge disposal should then be prohibited. In their particular approach, policy is predominant to science. The policy makes science

focus on the issue and presumes that that focus will ensure some answer will

be found. To quote an American expression, "necessity becomes the mother of

invention." I would call this an idealistic approach since the approach sets

an unattainable goal with the intent of forcing science to rise to the occasion and find and develop the technology to meet that goal. It was this concept that was accepted by the Congress of the United States, for example, in

regulating fuel consumption of automobile manufacturers in the 1970's by

setting higher mile-per-gallon attainment targets for U.S. automobiles that

was currently within the state-of-the-art at the time the law was passed. It

was also accepted by the Congress with the adoption of the Clean Air Act

amendments in 1990.

On the other hand, is the definition of the Group of Experts on the

Scientific Aspects of Marine Pollution, or GESAMP for short, which is a United

Nations organization of scientific experts tasked under U.N. authority, to

look at the technical and scientific issues associated with various international problems. In their response to definitions of the precautionary principle similar to the Friends of the Earth, they have the following to say:

"The concept of prec, ition is intrinsic to scientific prediction

and allows the inherent uncertainties associated with scientific

analysis and assessment to be accommodated. This concept has

recently been adopted as a specific instrument of environmental

4
protection policy under the titles of "The Principle of

Anticipatory Environmental Protection" and "The Precautionary

Approach." The assimilative capacity concept does not conflict

with these expressions of precaution. Several recent interpretations of the precautionary principle would seem to imply that

protection of the marine environment can be obtained solely by

progress towards a zero discharge policy. This is a flawed

approach. Rejection of scientifically based impact assessments

will prevent proper allocation of properties and rational evaluation of alternative options."

The GESAMP organization also has an agenda which is first to ensure that

there is a recognition from a scientific and policy standpoint the ocean

environment has a certain assimilative capacity; that it is po. without

significant environmental damage or impacts for the ocean to ab. and assimilate certain man-made effluents. Secondly, part of their agenda is to ensure

that in assessing a particular dredge disposal activity, all the disposal

options and alternatives are evaluated. If in that evaluation process, ocean

disposal is determined to be the least environmentally damaging alternative,

then it is the best alternative to implement. In this particular view,

science conditions and frames the proposed policy setting attainable limits as

established and defined by science. I would call this approach the pragmatic

approach because it sets an objective that is technically attainable. This is

the approach, incidentally, that is currently in place in the London Dumping

Convention Guidelines for the disposal of dredge material and, therefore, from

an international perspective, is the framework in which most national dredge

disposal laws and regulations are to be implemented.

What is the status of this idealistic versus pragmatic approach in the

international dredge disposal community? There is support for the idealistic

approach. That support comes primarily from the Nordic countries, from the

Federal Republic of Germany, and from the environmental groups who are very

active in the international arena. There also is a majority of support for

the pragmatic group. GESAMP is its strongest scientific advocate in the

international community, but a majority of the developed nations and developing nations support that approach as well. The debate continues, and the

United Nations Council on Economic Development, which will convene in Rio

de Janeiro in June of 1992, will be the next major forum at which this issue

may surface for discussion. I believe the outcome of the debate is not clear.

The environmental pendulum is constantly swinging, but the length of the arc

and the period of that swing remain unknown.

Let me close with some general observations, which are my own personal

views, as to how this effective marriage must ultimately be resolved. First,

I believe it is absolutely essential to achieve and attain an effective marriage of science and policy. Neither can be ignored. Policy that ignores

science will not work. It will be ridiculed by those at the implementation

level because they know they cannot implement something that is scientifically

not possible. Conversely, science that ignores policy does so at its own

peril. Regardless of how scientifically correct a particular point of view

may be, if it is not acceptable to those people who are charged with living or

implementing that science, it will not be done. Therefore, an effective marriage is absolutely essential.

5
Second, I do not believe that there is any sweeping, all inclusive

answer or solution to this challenge of an effective marriage. The alchemist

will never produce gold. What is required in each case, in each scientific

problem, is hard work, issue by issue, looking at each of the specific

problems to forge that marriage and to make it work.

Third and finally, there will be some failures. Some marriages will end

in divorce, some will end in annulment, some will be successful. But simply

because there are some failures does not mean that the institution of this

marriage of science and policy is flawed. The challenge we have is to look at

the particular issues with which we are wrestling and identify the terms and

conditions under which the marriage of science and policy can work. One

answer that will not work is to exclude one at the expense of the other.

I would apologize if you feel that in those conclusions I have not

answered the question as comprehensibly as you might have wished. But as I

stated at the beginning, my intent is to provide a thought-piece on how to

proceed and to stimulate some discussion on this particular issue. I appreciate your time and patience, and I will be happy to entertain questions as time

permits.

6
IMPROVEMENT OF WATER AND BOTTOM SEDIMENT QUALITY IN THE OSAKA

PORT AREA BY REMOVAL OF ACCUMULATED ORGANIC SLUDGE

Taizo Nakano

Port Development Department,

Comprehensive Planning Division,

Port and Harbor Bureau, Osaka City

2-8-24 Chikko, Minato-ku, Osaka City 552

ABSTRACT

This report has been prepared to explore the

improvement in water and bottom sediment quality

accomplished by the dredging and removal of organic

sludge in the Osaka Port area. The present survey has

clarified the following points:

a. Osaka City is currently dredging and removing

organic sludge accumulated in the Aji and other

rivers for use in sea reclamation in the Southern

area of North Port (Yumeshima). The results of

water quality monitoring conducted in the sea

areas around the disposal site show that the water

quality thus revealed is roughly on a level with

that of the Osaka Port water area, indicating the

appropriateness of these measures for excess water

to be discharged from the disposal site.

b. Sulfides and n-hexane are decreasing, indicating

improvement of the bottom sediment quality. The

chemical oxygen demand (COD), however, shows

fluctuations.

c. The water quality of Aji River shows the most

favorable results, as the biochemical oxygen

demand (BOD) has registered below 2 mg/f in recent

years. The Shirinashi River has been registering,

in recent years, even below 3 mg/I.

INTRODUCTION

Osaka Port, situated at the center of Osaka Bay and enjoying good meteorological and marine weather conditions, has developed historically as a

favorable port and serves presently as Japan's leading international trade

port at the heart of a vast hinterland.

The extensive hinterland around Osaka City, with a population of some

15 million, comprises a major area of production and consumption. It is one

of the two largest industrial and economic centers in Japan, the Tokyo area

being the other. Inevitably, Osaka City and its hinterland produce large

quantities of water-polluting substances which are carried into the Osaka Port

7
area via rivers, causing severe deterioration of water quality and bottom

sediment.

Thus, the Port and Harbor Bureau of Osaka City has been carrying out a

port and harbor pollution control project since 1974, in accordance with the

Osaka Area Pollution Prevention Plan. To improve the water and bottom sediment quality, accumulated organic sludge is being dredged and removed from

rivers and estuaries in the heavily polluted port and harbor area. Dredging

and removal in the central section of rivers were mostly completed by the end

of 1990.

This report has been prepared to explore the improvement in water and

bottom sediment quality accomplished by the dredging and removal of organic

sludge, as implemented in the bottom sediment improvement project in the

Osaka Port area.

REMOVAL OF ORGANIC SLUDGE IN OSAKA PORT

Outline of Removal and Disposal

Water pollution in the Osaka Port area is characterized by the predominance of artificial organic contamination, caused by rapid industrial development and urbanization in and around the watershed of rivers flowing into Osaka

Bay.

The water quality of the inner port , in which the river water stagnates, is particularly affected by the Neya River and other rivers in Osaka

City. The lower reaches of these rivers, the Aji, Shirinashi, and Kizu

Rivers, are tidal rivers in which sludge is accumulated especially easily, and

dissolved oxygen consumption, foul smell, and noxious gas generation are

caused by sedimented organic sludge stirred up by passing sea vessels.

Thus, in accordance with the Osaka Area Pollution Prevention Plan, since

1974 Osaka City has been dredging and removing accumulated organic sludge in

the heavily contaminated port and harbor area to stop the stirring-up of sedimented sludge and to improve the water quality, as well as to maintain aquatic

life-sustaining conditions by removing sulfides and oily substances from the

bottom sediment.

Figure 1 shows rivers in Osaka City and the areas in which organic

sludge removal is being carried out.

Removal Standard

The standard for accumulated organic sludge removal in Osaka City is set

at ignition loss of 15 percent or more because, as shown in Figure 2, a

remarkable correlation is found between ignition loss and COD, sulfides, and

oily substances (normal hexane extracts).

The concentration of substances contained in sludge which are fatal to

life forms is believed to be 500 ppm for sulfides and 15,000 ppm for COD.

While oily substances (N-hexane extracts) can arrest the transfer of dissolved

oxygen (DO) and block the respiratory systems of fish resulting in death, the

concentration that brings suffocation to fish in an extremely short period of

time is believed to be 2,000 ppm. Surveys of sludge accumulated in areas

8
frai sdg froVa ara

Northern area of North Pore (iha-thi e a y os

reoigsug o 5pretor o reignition loss o imroveth qultyo

.•-/ • ,,.I•_ inato-Kt

SOutl ne o re ofs/a a Ar. eas North Port (Yuse-shins)/"

o.,,a o., bonda,

peas organic slodge of removal arras

Figure n. Organic sludge removal areas

stretching over rivers and the port area show close correlation among ignition

loss, COD, sulfides, and oily substances, which serve as indices of organic substance content. Thus, the removal standard is set at ignition loss of

15 percent or more, so that the clear clay of lower layers can be exposed by

removing sludge of 15 percent or more ignition loss to improve the quality of

flowing water, restore life-sustaining conditions, and improve the

environment.

DISPOSAL OF ORGANIC SLUDGE

O~ujline of Terminal Di$posal Areas

Osaka City is currently dredging and removing organic sludge accumulated

in the AJi and other rivers to use it in sea reclamation areas.
Legend•.

0 Sludge layer

$O 15 a Clay layer

"x 4 spots in the Port area

5 16 0

!0 14

10

0 12 o- 0

0 1 000

-1 o0 -03

0

2

01 2

00

o 0

to 20 30 10 20 30

Ignition lossCM Ignition 1oss(M

14

12

10

4J - !

4 )

2 0 "S ' no" Ia 0 Ii 00 i•

.0

10 20 30 1 0 3

Isiinls()Ignition loss(%)

[4

s2

tO.20030

Figure 2. Correlation diagrams

There are two terminal disposal sites for dredged sludge, the northern

and southern disposal sites, both located at the farthest end of Osaka Bay,

west of Osaka City. Sludge was accepted at the northern site (Maishima) until

1986 and has been accepted at the southern site (Yumeshima) since 1987.

Table 1 and Figure 3 show some details of the southern disposal site in

North Port (Yumeshima). On the disposal site, dredged sludge is disposed of

in the second and third areas, along with excavated earth and dredged earth

and sand from within the port area.

10
TABLE I. SOUTHERN DISPOSAL SITE IN NORTH PORT

Southern Disposal Site in North Port

Area 288 ha

(First area: 73 ha; Second & Third areas: 215 ha)

Capacity 50,000,000 ms3

Total length of seawall 9,742 m

Construction period 1977-1989

Acceptance period 1985-1995

Acceptance condition 15,810,000 m 3 (approx 32%)

Types of waste accepted First area: ordinary waste, industrial waste;

Second & Third areas: dredged earth and sand,

excavated earth from construction sites

Seawall F 1.163&

• area Third area `

Partition djike'

Second area

Seawall H '•

Note: The North Port disposal site is Osaka City's terminal disposal site,

whose First Area accepts ordinary waste and sludge from city water

and sewerage systems.

Figure 3. Layout of the southern disposal site (Ytuneshima)

Structure of the Seawall and the

Partition Dike on the DisRosal Site

Figures 4-7 show the structure of the seawalls and the partition dikes

of the North Port southern disposal site, which is presently accepting organic

sludge.

Seawall F

It is necessary to minimize interference with a ship's navigational

route which faces this seawall (Figure 4). For this reason, as well as for

reliable and economical construction, the caisson structure is being adopted.

For subsoil improvement, the sand compaction pile method is employed to

11
3 1.40 21.00 4.0 0

.2 0 .0 0 L . 0 0 1 .0

L1L~-5 L DO it + 00 +4 .50 I:Jat.. 

Cowering stone t edI& bkad&d

Dipiceet *I s. 00 sand sat (thjcknses:l.2 a) =n"and pile (disseter:400sa;

Foundation rubble 7:un~dý , ,ad macinpl squarely positioned. ctc-2. Os)

34.20.00

ndy gravel stratum

15. 00. 13. 00 2 0. 00 14. 00 48.00

Figure 4. Seawall F

minimize the amount of excavated earth and sand. Moreover, the embankment

method with sand mound is employed to secure complete disposal of excavated

earth and sand.

Seawall Hi

The wave dissipation caisson structure is employed for this seawall

(Figure 5) since it is exposed to rough waves, especially during winter, from

the open sea. For subsoil improvement, the sand compaction pile method is

adopted to minimize the amount of excavated earth and sand. Moreover, the

embankment method with sand mound is employed to secure complete disposal of

excavated earth and sand.

Partition Dike

Since the North Port disposal site accepts various types of waste for

landfill, including organic sludge and ordinary waste, partition dikes of the

double steel sheet pile structure are erected to separate disposal areas

(Figure 6). Moreover, since the partition dikes can handle traffic on their

top surface, they also serve to facilitate reclamation work and maintenance

and control.

The steel sheet piles of the partition dike (Figure 7) in the first area

are made longer than usual and driven into the clay stratum to secure better

water-tightness.

12
23. 30 28. 20 17.00 4.00

20.000.00

L--L DO.U. O+ 1 0.B 3kEb 1en man t --- Dredged earth and sand

Dispace at andsand mat(thickness:1. 2.)

-1 0Sand compaction Vil sand pile(diaaeter:400*@:aqusartly positioned ctc-2. 0.)

Foundation rubbIe m-onud (As.50%LAs70%) -40

-- 24.00

_________ -30 .00

-gndravel strate' m. * . . .. :- I4.0 20.00 3 0. 0 0 065. 00

Figure 5. Seawall H

10. 00 15. 0 0 10 . 00 Ti ro

DL-2.0+ sand 00un san fil anmun

Sandyee graeelstratu

patto dike Potcto

133
£

10. 00 15. 00 10. 00 Fater-tight sheet pile

DL+11.00 Tie roS

Fiue7 atto d -ieo Steel sheet pile DL + 5. 00 :

r enaPeeai MProtection

Water and Oil Contamination1:

dredgd earhandsand are acceptd in thethird ara1n:fo6h tidae

ornSand nat (thickness:e . 2m)

Sand pile. squarely s sitioned se=i400m ctc=2.a00

DL- 28. O00

DL- 37. i0 : Sand gravel stratue

; 50.00 _150.00

Figure 7. Partition dike with longer sheet piles in

first area

Environmental Preservation Measures

Measures to Prevent Muddy Water and Oil Contamination

In the southern disposal site of North Port (Yumeshima), waste water is

released into the open sea via the weir from the second-area outlet when

dredged earth and sand are accepted in the third area, and from the third-area

outlet when dredged earth and sand are accepted in the second area (Figure 8).

This process is devised so as to expedite sedimentation.

Outlet

/ Diffusion Q - protector r First .are / Third area 4 ,,

~prtition• Dike (3)

Oxidasion basin Second area ,

Diffuso

outlet /"protector

Seawall

Figure 8. Wastewater flow in the southern disposal site

14
Since dredged earth and sand are disposed through discharge pipes by an

unloader ship, it is possible to conduct surveys on the spread of muddy water.

Identifying the spread allows diffusion protectors to be installed accordingly

to prevent secondary pollution; that is, the spread of muddy water in surrounding sea areas caused by the disposal of organic sludge.

Surveys of Excess Water

After use of the northern site, in 1987 the second area of the southern

disposal site of North Port started accepting dredged earth and sand. On

transfer of the disposal site from north to south, it was deemed necessary to

carry out relevant surveys prior to disposal to secure optimal, long-term

management of excess water produced in the process of reclamation.

The surveys relate to the water quality, bottom sediment, and biological

conditions within the disposal site, as well as phytoplankton primary production--which is a factor for eutrophication--sedimentation speed, and the

spread of discharged earth and sand which accompanies reclamation work.

The survey on phytoplankton primary production is conducted to examine

the correlation between phytoplankton growth and COD and other indices, since

it is surmised that the increase of nutrient slats eluting from discharged

earth and sand (such as N and P) causes eutrophication and extraordinary proliferation of phytoplankton at the disposal site, which in turn raiqes pH and

COD values.

The estimated results of the COD balance within the disposal site (1990

survey) can be summarized as follows:

a. The COD at the time of disposal of dredged earth and sand into the

site was 7.0 - 25.0 t/month.

b. The COD generated within the site by the growth of phytoplankton was

44.4 - 102 t/month.

c. The majority of the COD released into the site and generated there

underwent sedimentation, decomposition, and ingestion in the site.

The COD value at the time of discharge out of the site was 9.9 -

38.7 t/month, roughly the same as the value at the time of release

into the site.

The survey on the spread of discharged earth and sand accompanying reclamation work is conducted to measure turbidity, flow direction, and flow

speed inside the disposal site, in order to determine the staying flow time

required to expedite the sedimentation of earth particles. The survey results

are then examined to determine the position and direction of sand discharge

pipes, methods of installing diffusion protectors, and so on.

Constant Monitoring of the

Quality of Discharged Water

In the North Port southern disposal site (Yumeshima), water discharged

via the excess water outlet into the sea is automatically monitored 24 hr a

day to fulfill the voluntarily set quality standards shown in Table 2. The

monitoring methods shown in Table 3 are followed. The continuous monitoring

15
TABLE 2. TARGET WATER QUALITY STANDARDS

Item Target Standard Notes

Hydrogen-ion concentration (pH) 5-9 Effluent standards 5-9

Dissolved oxygen (DO) 2 mg/I or above Environmental standards 2 mg/lor above

Normal hexane Plant and 10 mg/I or below Effluent standards

extracts animal oil 30 mg/I or above

(oily substances) Mineral oil 3 mg/I or below Effluent standards _ _5 mg/I or below

Suspended substances (SS) 50 mg/I or below Effluent standards

150 mg/I or below

Chemical oxygen demand (COD) 40 mg/I or below Effluent standards

1_ 1 120 mg/I or below

Note: "Effluent standards" are in compliance with the Water Pollution

Control law; SS and COD refer to daily average values.

TABLE 3. OUTLINE OF CONSTANT WATER QUALITY MONITORING

Item Measuring method Notes

Water temperature Platinum thermometer

pH Glass electrode

Turbidity Diffused light method

SS (Turbidity meter) Calculated from turbidity

by a correlation formula

COD (UV meter: UV photome- Calculated from UV value by

ter) a correlation formula

DO Galvanic method

is carried out in order to promptly devise appropriate measures to prevent

secondary pollution which may be caused by discharged water into the surrounding sea areas during the reclamation process.

ENVIRONMENTAL MONITORING IN THE SEA

AREAS SURROUNDING THE DISPOSAL SITE

Outline

In the sea areas surrounding the North Port southern disposal site

(Yumeshima), water quality and bottom sediment surveys are periodically

carried out to monitor the environment. Table 4 and Figure 9 show the details

of the surveys.

16
TABLE 4. ENVIRONMENTAL MONITORING SURVEYS

Category Item Frequency Measuring items

Water General Monthly Color tone, smell, pH, BOD,* COD, DO, SS,

quality clorine ion, S-BOD, S-COD, S-TOC

Special Once every Cadmium, lead, arsenic, cyan, copper,

health 4 months iron, zinc, PCB,** manganese, total chrorelated mium, nickel, fluorine, n-hexane,

extracts, organic phosphorus, hexavalent

chromium, general bacteria, coliform group

Others Monthly Total nitrogen, ammoniac nitrogen, nitrate

nitrogen, nitrite nitrogen

Once every Total mercury, alkyl mercury, total phostwo months phorus, phosphoric acid phosphorus,

chlorophyll a, pheophytin

Bottom General Annually Water consent, pH, ignition loss,

sediment special sulfides, COD, cadmium, lead, arsenic,

health- copper, iron, total mercury, zinc,

related manganese, total chromium, nickel, PCB,

organic phosphorus, hexavalent chromium,

alkyl mercury

* BOD - bochemical oxygen demand

** PCB - polychlorinated biphenyls

0

Thir ara .Fourth area 2

Second area

0 O ..... later quality surveys

S..... Bottom sediment surveys

Figure 9. Locations of environmental monitoring surveys

Monitoring Results

The results of water quality monitoring conducted in the sea areas

around the North Port southern disposal site recorded values for COD and DO,

17
representative water pollution indices, as shown in Table 5. The water quality thus revealed is roughly on a level with that of the Osaka Port water

area, indicating the appropriateness of these measures for excess water to be

discharged from the disposal site.

TABLE 5. RESULTS OF ENVIRONMENTAL MONITORING

Areas surrounding the Osaka Port water area

disposal site

COD DO COD DO

1987 5.3 8.5 4.3 6.5

(6.3-3.7) (9.0-7.8) (5.3-3.0) (7.6-4.9)

1988 4.5 8.9 4.3 6.7

(5.4-3.9) (9.4-8.5) (5.3-3.5) (8.5-5.2)

1989 4.3 7.5 4.0 6.7

(4.9-3.2) (8.9-7.0) (5.1-3.0) (8.4-5.4)

1990 4.6 7.2

1 (4.8-4.0) (7.4-7.0)

Note: Surveys in the surrounding sea areas are conducducted by the Port and Harbor Bureau, and those

in the Osaka Port water area by the Environmental

Department.

Figure 10 illustrates monthly changes in COD during 1989. It also shows

that remarkable differences in the COD values measured in spring and summer

existed between the areas around the North Port southern disposal site and the

Osaka Port water area, while there was little difference in the values

measured in autumn and winter.

Figure 11 shows monthly changes in pH, drawn to examine the difference

between the two areas. The pH values show a tendency similar to COD, i.e., a

large difference in pH existed between the two areas measured in spring and

summer as well.

It is assumed that abnormally active photosynthesis, at the time of

extraordinary emergence of phytoplankton (red tide) accompanying eutrophication, accounts for the higher pH values.

RESULTS OF ORGANIC SLUDGE REMOVAL AND IMPROVEMENT

OF WATER AND BOTTOM SEDIMENT QUALITY

Results of Organic Sludge Removal

Since 1974, organic sludge dredging and removal have been carried out as

a port and harbor pollution control project. Table 6 shows the annual volume

of earth dredged from three rivers.

18
(Unit:mg/9)

Areas surrounding

the southern site

Osaka Port water areas

I. I I ...

Apr. May. Jun. Jul. Aug. Sep. Oct. Nov. Dec. Jan. Feb. Mar.

Figure 10. Monthly changes in COD

Areas surrounding

the Southern site

Osaka Port water areas

Apr. May. Jun. Jul. Aug. Sep. Oct. Nov. Dec. Jan. Feb. Mar.

Figure 11. Monthly changes in pH

19
TABLE 6. AMOUNT OF DREDGED ORGANIC SLUDGE

(Unit: 1,000 m3 )

1974 1975 1976 1977 1978 1979 1980 1981 1982

Shirinashi .. .. 141 46 .. .. .. 52 --

River I

Ali River 110 244 48 115 179 256 120 21 146

Kizu River .. .. .. 124 1i1 -- 136 178 141

Total 110 244 189 285 290 256 256 251 287

1983 1984 1985 1986 1987 1988 1989 1990 Total

Shirinashi .. .. 73 37 .... .. . 349

River

Aji River 279 252 178 14 149 103 131 9 2,354

Kizu River .. .. 24 149 138 124 135 129 1,389

Total 279 252 275 200 287 227 266 138 4,092

In the future, continued removal of accumulated sludge is planned for

the Aji, Shirinashi, Kizu Rivers to improve the water quality. The five-year

plan from 1991 to 1995 includes removal of sludge from the central section of

the Shorenji River and along the shores of the Aui and Kizu Rivers. Table 7

shows the dredging volume planned for the five-year period starting in 1991.

TABLE 7. PLANNED AMOUNT OF ORGANIC SLUDGE TO BE DREDGED

(Unit: 1,000 M3 )

1991 1992 1992 1994 1995 Total

Shirinashi River .. .. 10 10 16 36

Aii River 20 60 60 60 57 257

Kizu River .. .. .. 10 20 30

Total 20 60 70 80 93 323

ILinrovement of Bottom Sediment

The annual changes in the respective bottom sediment quality of the

Shirinashi, AJu, and Kizu Rivers, in which organic sludge dredging and removal

have been carried out, are shown in Figures 12-15.

Dredging and removal are almost completed in the Shirinashi and the Aji,

and the ignition loss of these two rivers, originally some 20 percent, has

been reduced to 13.5 and 11.6 percent, respectively, each below the target

15 percent. In the Kizu River, where dredging is still in progress, the

20
(Unit:%)

•- Shirinashi River

-Aji River ...... Kizu River

SI ! I i I I i i , I I I I I I I i

1974 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 Year

Figure 12. Ignition loss

(Unit:ug/d-g)

- Shirinashi Lver - Aji River ............ Kizu River

I I I i I I I , , I I I i I I i i !

1974 75 76 77 78 79 80 81 8? 83 84 85 86 87 88 89 SO 91 Year

Figure 13. Sulfides

21
(Unit :./d-g)

60C . . . , . . . .

- Shirinashi River

,- Ai River .......... ............ Kizu River

g I I I I I I I I I I

1974 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 Year

Figure 14. Hexane

(Unit:@g/d-g)

100 .. ..

-- Shirinashi River

-Aji River ........... Kizu River

1974 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 Year

Figure 15. COD

ignition loss has been reduced from the initial figure of about 30 percent but

is still around 16.0 percent.

Sulfides and n-hexane are also decreasing, indicating improvement of the

bottom sediment quality. COD, however, shown fluctuations, and future measures for bottom sediment quality improvement will require examination.

Water Ouality Improvement

Figure 16 shows the annual changes in water quality in terms of BOD in

the Shirinashi, AJi, and Kizu Rivers, in which organic sludge dredging and

removal have been carried out.

22
(Unit:4/I)

0.

-Shirinashi River

-Aji River

• Kizu River

... Osaka City

river basic

10 "

.....

............ . . ...

1974 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 9C Year

Figure 16. Annual changes in water quality

(in terms of BOD)

The Aju River shows the most favorable results, whose BOD figures have

leveled off since 1976 and have registered below 2 mg/I in recent years. The

Shirinashi River has been registering below 4 mg/I since 1976 and, in recent

years, even below 3 mg/I.

Meanwhile, the Kizu River, in which dredging work is still being continued, showed a drastic decrease of BOD up until 1979, which has then leveled

off since 1980.

The annual changes in the Osaka City river basins (see Figure 17) indicate an overall tendency of decline in BOD because of the established water

quality regulations: BOD decrease drastically until 1982 and has leveled off

since 1983. The Kizu River shows a similar pattern to this tendency.

FUTURE CHALLENGES

In the Osaka Port area, the river water and bottom sediment quality have

been improving, thanks to the positive effects of effluent restrictions made

mandatory by laws and regulations, as well as the dredging and removal of

organic sludge accumulated in rivers within the port area. For further

improvement in the future, the following challenges will have to be faced.

A New Terminal Disposal Site

At present, the North Port disposal site serves as Osaka City's terminal

disposal site for dredged earth and sand, waste, and other matter. However,

the site is scheduled to discontinue accepting matter for disposal in 1995.

Thus, it is imminently necessary to secure a new terminal disposal site.

Considerations are currently being made for an earliest possible realization

of a new disposal site, while the construction period for seawalls is being

taken into account.

23
js7

//

/ 5

41

Note: Numbers indicate water quality survey spots.

Figure 17. River and port basins

For the construction of a new terminal disposal site, careful consideration should be given to preservation of the surrounding sea environment.

Likewise, a scientific environmental assessment, including prior surveys on

water qu~olity and tidal currents, will need to be made.

Consideration of

Organic Slud~e Removal Standard

Ignition loss of 15 percent is set as the target standard for removal of

organic sludge accumulated in rivers in the Osaka Port area. Yet, as sumnmarized in this report, some items measuring bottom sediment quality have not

improved to achieve this target. For this reason, as well as to secure

imrovement of the water quality of rivers and the Osaka Port area, it is

necessary to review the improvement measures, including this removal standard.

Accordingly, research and surveys should be continued in the future.

24

? !
Water Quality Control at

the UVRer Reaches of Rivers

To improve the water quality of Osaka Port, it is essential to control

the water quality of rivers flowing into the Port area, especially at their

upper reaches. While the sewerage system coveragi is almost 100 percent in

Osaka City, areas at the upper reaches of rivers are not yet fully covered by

sewerage systems, thus hindering the improvement of water quality of the Neya

and the Yanato Rivers.

It is expected that extensive water quality preservation measures,

covering all the basins of rivers flowing into Osaka Port, will be required in

the future. Thus, a major challenge for water pollution control will be the

promotion of extensive measures involving both upper and lower reaches of

rivers.

Moreover, marked tendencies of eutrophication found in the Osaka Port

area, coupled with high pH values in the terminal disposal site, urgently call

for effective countermeasures.

In consideration of these challenges, Osaka City is currently planning

to introduce advanced water treatment systems to upgrade sewerage treatment

and to combat eutrophication. It is expected that this plan will reduce the

water pollution load (COD) released from the sewerage treatment plant and,

when combined with effective countermeasures against phosphorus, will help

prevent eutrophication.

The improvement of water and bottom sediment quality in the Osaka Port

area accomplished by the dredging and removal of accumulated organic sludge

has been described, along with measures for the discharge of excess water from

the disposal site and for environmental monitoring in the areas surrounding

the disposal site. It is hoped that this report will contribute in some way

to the environmental improvement of port and harbor areas in Japan and the

United States.

25
TECHNOLOGIES FOR REMEDIATION OF

CONTAMINATED SEDIMENTS IN THE GREAT LAKES

Norman R. Francingues, Jr., Daniel E. Averett

Environmental Laboratory

U.S. Army Engineer Waterways Experiment Station

3909 Halls Ferry Road

Vicksburg, Mississippi 39180-6199

ABSTRACT

Technologies that have been identified as feasible for

remediating contaminated sediment and being considered

for demonstration in the Great Lakes are presented in

this paper. The review encompasses the components

required for removal of highly contaminated sediment.

Technologies reviewed concentrate on those involving

treatment of the contaminated sediment. Approximately

200 technology process options were reviewed for

effectiveness, implementability, and costs. However,

few of these processes have been applied to contaminated sediment on a full scale. Most of the technology evaluations have been on the bench scale with

limited pilot testing results available for

assessment. Therefore, further testing and evaluation

of the most promising technologies is being conducted

under the ARCS program at the Buffalo River, Ashtabula

River, Saginaw River, Sheboygan River, and Grand

Calumet River/Indiana Harbor areas of concern.

INTRODUCTION

Thank you, Co-Chairmen Bates for the gracious introduction. Co-Chairman

Kawashima and our distinguished delegates from Japan and the United States, it

is my distinct pleasure and honor to be here today to attend my fourth meeting

of Experts on the Management of Highly Contaminated Toxic Bottom Sediments. I

have many fond memories of the 10th meeting which was held in Kyoto in 1985.

At that meeting, I discussed some of the promising technologies we were

assessing for the management of contaminated dredged material in the United

States. Since that time, there has been considerable emphasis placed on the

identification, assessment, and remediation of highly contaminated toxic bottom sediments in the U.S. and around the world. To address this problem, a

number of major Federal and state laws, regulations, and programs have

evolved.

ARCS PROGRAM

Prominent among the new programs is the Assessment and Remediation of

Contaminated Sediments (ARCS) program which is managed by the U.S. Environmental Protection Agency (FPA). For the past two to three years, the

U.S. Army Corps of Engineers (CE) has been working with EPA's Great Lakes

26
National Program Office (GLNPO) to implement the requirements of Section

118(c)(3) of our Federal Water Quality Act of 1987. This Section specifically

directs the EPA to "carry out a five-year study and demonstration projects

relating to the control and removal of toxic pollutants in the Great Lakes,

with emphasis on the removal of toxic pollutants from bottom sediments"

(Horvatin 1989). The Act specified that priority Areas of Concern for implementation of demonstration projects were Saginaw Bay, Michigan; Sheboygan

Harbor, Wisconsin; Grand Calumet River, Indiana; Ashtabula River, Ohio; and

Buffalo River, New York.

Major Study Participants

The EPA operating through its GLNPO is responsible for the ARCS program

in the Great Lakes. The Department of Army operating through its CE has

entered into an agreement to provide technical assistance to EPA and GLNPO to

carry out the study and demonstration program. The CE's North Central Division and Districts with technical assistance from the U.S. Army Engineer

Waterways Experiment Station (WES), Vicksburg, Mississippi, is responsible for

assessing the engineering feasibility of a variety of contaminated sediment

remediation alternatives and technologies. As part of this effort, my coauthor, Dan Averett, and others at WES, completed a review of technologies for

the containment and treatment of contaminated sediments either in place or

after removal.

Purpose of Technology Review

The purpose of the technology review was to identify technologies and

process options that may be feasible for remediating Great Lakes contaminated

sediment and that may be considered for demonstration under the ARCS program.

Over 300 process options were reviewed which resulted in approximately

40 processes having potential for bench and pilot testing. The technologies

reviewed included those involving removal of contaminated sediment with subsequent transport, treatment, containment, or disposal, and those for nonremoval

alternatives, such as in situ treatment or containment of contaminated sediment. A report (Averett et al. 1990) of this review of technologies was prepared and I have provided Co-Chairman Mr. Kawashima with a copy.

Purpose of Presentation

To prepare for this meeting, I have summarized our review of technologies study and will present only a brief description of a variety of technologies and basic alternatives for managing contaminated sediments in the Great

Lakes and elsewhere in the U.S. Due to the limited time for this presentation, my verbal remarks will be restricted to only a few of the technology

types and processes that have been evaluated or are being demonstrated in the

Great Lakes.

COMPONENTS OF REMOVAL

The components for alternatives that require removal of contaminated

sediments are: (a) excavation of sediment, (b) transport of dredged sediment,

(c) pretreatment of dredged sediment, (d) treatment of dredged sediment,

(e) disposal of dredged materials, and (f) water (effluent and leachate)

treatment. A variety of technologies are potentially available for each

27
component; however, only a limited number have actually been applied on a

pilot scale or full scale.

Factors that need to be considered when evaluating removal alternative

technologies include the following: (a) state of technology, (b) availability, (c) effectiveness, (d) implementability, and (e) cost.

Excavation Component

Principal concerns during excavation operations are the prevention of

contaminant releases from the sediment being removed with subsequent transport

of contaminants to a previously uncontaminated area and efficient removal of

contaminated sediment without excessive overcutting. If an unavoidable

release occurs, undesirable consequences could result in regards to the environment, costs, and public relations. Overcutting increases the volume of

material for treatment or disposal and increases costs. Technologies for the

excavation of contaminated sediment include the following:

a. Selection of appropriate mechanical or hydraulic dredges

b. Use of operational controls during excavation activities

c. Deployment of barriers during sediment removal

Transport Component

Primary transportation methods used to move contaminated dredged

sediment include pipelines, barges or scows, and hopper dredges. Overland

transport could also include railways and trucks.

Pretreatment Component

Pretreatment technologies are defined for the purpose of this talk as

technologies that prepare dredged sediment for additional treatment or disposal. These technologies are designed to accelerate treatment in a disposal

site, to reduce the water content of the dredged material, or to separate

fractions of the sediment by particle size. Pretreatment technology process

options are dewatering, particle classification, and slurry injection. These

processes are primarily applicable to hydraulically dredged sediment. Physical separation or particle classification is being demonstrated on a pilot

scale on sediments from the Saginaw River. Approximately 300 tons of PCBcontaminated sedime-.t will undergo soil washing and hydrocycloning to separate

80 percent sand from the remaining silt fraction. The pretreatment will prepare the silt for further treatment using bioremediation technology being

demonstrated at the Sheboygan Harbor, Wisconsin site.

Treatment Component

Many of the process options are not stand alone processes but are components of a system that may involve multiple treatment processes to address

multiple contaminant problems. Most of these processes also require one or

more of the pretreatment processes discussed above. Technology types for the

treatment component are: (a) biological, (b) chemical, (c) extraction,

(d) immobilization, and (e) thermal.

28
Biological Processes

Biological degradation technologies use bacteria, fungi, or enzymes to

break down polychlorinated biphenyls (PCBs), pesticides, and other organic

constituents into innocuous or less toxic compounds. The microorganisms may

be indigenous microbes, conventional mutants, or recombinant DNA products.

Biodegradation processes have not been applied and evaluated for contaminated

dredged material other than on a bench scale. Several of the conceptual processes are proprietary processes that may be available on a pilot scale, and

new vendors continue to enter this market. The Bio-Clean process, being considered for the Hudson River, is estimated to cost $130 to $270 per cubic

yard. A potentially lower cost would be incurred 1f biodegradation can be

conducted in a confined disposal facility (CDF).

Because of the dependence of biological processes on carefully maintained environmental conditions, reliability of these processes is questionable. Implementability for most of these processes is difficult because of

the developmental nature of these processes for contaminated sediment and

because of long time periods and large systems that will likely be required

for treatment of contaminated sediment.

Enhanced natural biodegradation of PCB's in sediments is being evaluated

in a p!>L.t contained treatment facility (CTF) at the Sheboygan River Superfund

remedlation project. The CTF was designed to accommodate approximately

3,000 cu yd of sediments dredged from the upper Sheboygan River. The CTF is

divided into two treatment sections with controls to allow for regulation of

nutrient and oxygen conditions for the bacteria. The control sections will

not receive added nutrients to enhance biodegradation. Both anaerobic and

aerobic biodegradation conditions are being assessed in the study.

Chemical Processes

Chemical treatment technologies use chelating agents, bond cleavage,

acid or base addition, chlorine displacement, oxidation, or reduction in the

destruction, detoxification, or removal of contaminants found in the contaminated media. Few of these technologies have been used for treatment of

organic and heavy metal contaminants in sediment. Chemical treatment technologies considered include chelation, chemical hydrolysis, and detoxification.

Implementability for chemical processes is difficult because of materials handling and process control requirements that have not been fully demonstrated for application to dredged sediment. Costs for these processes have

not been reported and are difficult to quantify, but they are expected to

exceed $100 per cubic yard.

Extraction Processes

Extraction is the removal of contaminants from a medium by dissolution

in a fluid that is later recovered and treated. Soil flushing and soil washing are other terms that are use to describe extraction processes. A key

element of an extraction process is the ability to separate the contaminant

from the solvent so that the solvent can be recovered for reuse in the process. Also important is the toxicity of the solvent. Most processes require

multiple extraction cycles to achieve high removal efficiencies. Follow-on

29
treatment processes are required to treat or dispose of the concentrated contaminant stream.

Implementability for most of these processes is difficult because of the

lack of full-scale development for handling sediment and the problems of solvent recovery and potential toxicity of residual solvents. Costs are not well

documented but are expected to exceed $100 per cubic yard.

Solvent extraction will be demonstrated for highly contaminated sediments from the Grand Calumet and Indiana Harbor Canal. A pilot study of the

triethylamine (TEA) extraction process will be evaluated for removal of polyaromatic hydrocarbons (PAHs) and PCBs from the sediment.

This technology has been evaluated previously on sediments contaminated

with PCBs from the New Bedford Harbor Superfund Site and on sediments/soils

contaminated with creosote from the Bayou Bonfouca Superfund Site in Slidell,

Louisiana.

Immobilization Processes

Immobilization processes are defined as technologies that limit the

mobility of contaminants for sediment placed in a confined site or disposal

area. The environmental pathway most affected by these processes is transport

of contaminants to the ground water or surface water. Most of the immobilization processes fall into the category of solidification/stabilization (S/S)

processes. Objectives of S/S are generally to improve the handling and physical characteristics of the material, decrease the surface area of the sediment

mass across which transfer or loss of contaminants can occur, and/or limit the

solubility of contaminants by pH adjustment or sorption phenomena.

Effectiveness of S/S processes is usually evaluated in terms of reduction of leaching potential. Reductions are process and contaminant specific

with immobilization of some contaminants accompanied by increased mobility of

other contaminants. Implementability for most of these processes is better

than chemical or extraction processes because they are not as sensitive to

process control conditions. The opportunity for in situ S/S within a CDF is

also an advantage. Costs for these processes are generally less than $100 per

cubic yard.

The immobilization of residual wastes from the thermal desorption demonstration project at the Buffalo River Site will be evaluated. Previous bench

scale studies of S/S processes have been conducted for the Indiana Harbor and

Buffalo River sediments.

Thermal Processes

The thermal type technologies are incineration processes, pyrolytic

processes, vitrification processes, supercritical and wet air oxidation, and

other processes that require heating the sediment several hundred or thousands

of degrees above ambient. Thermal desorption or extraction of low level PAHs

in sediments is being demonstrated for the Buffalo River and Astabula River

demonstration projects. Low temperature thermal desorption does not destroy

the organics. Instead, it removes the low temperature volatile compounds

(VOCs) through the vaporization of the organics and water from the sediment.

The VOCs and water vapor are collected for further treatment and disposal.

30
Thermal processes are generally the more effective options for destroying organic contaminants, but they are also the more expensive. Costs for

thermal processes range from several hundred dollars to over a thousand

dollars per cubic yard.

SUMMARY

The technologies available for managing contaminated sediment can be

categorized as either nonremoval or removal. The removal technologies

reviewed for this paper have been assessed for their effectiveness, implementability and costs, and a brief description of the treatment technologies being

demonstrated in the Great Lakes ARCS program is provided. Approximately

30 technology categories and over 200 process options were reviewed as a basis

for this presentation. These pilot projects will provide a basis for advancing the technology gaps that now exist for incorporation of these technologies

into remedial action plans for contaminated sediments.

REFERENCES

Averett, D. E., Perry, B. D., Torrey, E. J., and Miller, J. A. 1990. "Review

of Removal, Containment, and Treatment Technologies for Remediation of Contaminated Sediment in the Great Lakes," Miscellaneous Paper el-90-25, U.S. Army

Engineer Waterways Experiment Station, Vicksburg, MS.

Horvatin, P. 1989. "Provisional Strategy for Assessment and Remediation of

Contaminated Sediments (ARCS)," U.S. Environmental Protection Agency, Great

Lakes National Program Office, Chicago. IL.

31
DEVELOPMENT OF A LEACHING PROTOCOL FOR EVALUATING

GROUND WATER IMPACT FROM CONTAMINATED SEDIMENT

James M. Brannon, Thomas E. Myers

U.S. Army Engineer Waterways Experiment Station

3909 Halls Ferry Road

Vicksburg, Mississippi 39180-6199

ABSTRACT

The U.S. Army Engineer Waterways Experiment Station is

developing laboratory tests and data interpretation

algorithms for predicting leachate quality in confined

dredged material disposal facilities (CDFs). Leachate

quality predictions are needed for evaluation of

potential impacts of leachate seepage on foundation

soils and ground water. Both batch and column laboratory leach tests are under investigation. A sequential batch leach test is being developed to provide a

short-term laboratory test that describes the distribution of contaminants between aqueous and solid

phases. Column leach tests are being developed as

laboratory-scale physical models of contaminant

leaching in a CDF. Current studies show that sediment

salinity and oxidation status significantly affect

contaminant leaching. Sediments from freshwater

environments generally behave according to classical

desorption theory. However, leaching of sediments

from estuarine environments with freshwater results in

nonideal behavior that significantly complicates prediction of long-term leaching trends. Nonideal behavior is due to release of sediment organic colloids as

ionic strength is decreased through salt wash out.

Data from sequential batch leach tests clearly indicate that elution of several pore volumes through

estuarine dredged material is necessary to produce

maximum concentrations of contaminants in leachate.

INTRODUCTION

When contaminated dredged material is placed in a CDF, contaminants may

be mobilized and transported to the site boundaries by leachate generation and

seepage. Subsurface drainage and seepage through foundation soils and dikes

may then reach adjacent surface and ground waters and act as sources of contamination (Figure 1). Therefore, techniques for predicting leachate quality

in CDFs are needed to establish sound engineering and environmental data for

the selection, design, and management of CDF's.

The U.S. Army Corps of Engineers (CE) has initiated CDF leachate investigations and has developed a theoretical framework for prediction of leachate

quality based on mass transport theory. The theoretical framework includes

32
IO~ bO

0

.j r-t/.F!ou

r4 -Lz 'T I

IL

.Z N

Z 4 2

U. 0

OO *I0 0 4

0 c c t oU , bO

CC 0 -00

~ -00 4 1

2-I 

zz

.. ,o0 =~~ 

0

F0

AL' ccl~ I

N.M1..bO

Iu 0

33
both batch and column testing. Batch testing provides a quick, relatively

easy method for determining the distribution of contaminants between dredged

material and leachate, while column testing more closely approximates contaminant losses from a CDF under field conditions. Batch and column results are

integrated by using distribution coefficients derived from batch testing in

conjunction with column operating parameters and mass transport theory to

compare predicted results with those observed from column leaching

experiments.

We report here results of batch and column tests conducted with dredged

material. Comparability of batch and column data and directions for further

research are also discussed.

BACKGROUND

Contaminant migration via leachate seepage is a porous-media contaminant

transport problem (Figure 2). Leaching is defined as interphase transfer of

contaminants from dredged material solids to the pore water surrounding the

solids and the subsequent transport of these contaminants by pore water seepage. Thus, leaching is interphase mass transfer (Equation 2, Figure 2)

coupled with porous-media fluid mechanics (Equation 1, Figure 2). Interphase

mass transfer during dredged material leaching is a complicated interaction of

many elementary processes and factors such as adsorption, desorption, precipitation, dissolution, surface complexation, redox potential, ionic strength,

and pH. A complete description of all these processes, their interactions,

and factors affecting these processes is not presently possible. Instead, a

lumped parameter, the distribution coefficient (Kd), is used to describe the

distribution of contaminant between aqueous and solid phases.

To simplify predictive laboratory tests and mathematical models for

routine use, local equilibrium conditions are assumed between the dredged

material and leachate. When the rate at which water moves is slow relative to

the rate at which equilibrium is approached, a local chemical equilibrium

exists between the pore water and the sediment solids. The local equilibrium

assumption implies that as a parcel of water passes a parcel of dredged material solids, the water and solids come to chemical equilibrium before the

parcel of water moves to contact the next parcel of dredged material solids.

Leachate quality at the surface and at the bottom of a CDF may differ, while

both are in equilibrium with the dredged material solids. Some soil column

studies have indicated that the local equilibrium assumption is valid for pore

water velocities as high as 10-5 cm/sec (Valocchi 1985). In reality, equilibrium controlled desorption requires an infinitely fast desorption rate. However, if the critical interphase transfer rates are sufficiently fast, the

equilibrium assumption can yield results indistinguishable from those obtained

by full kinetic modeling (Jennings and Kirkner 1984, Valocchi 1985, Bahr and

Rubin 1987).

In addition to being a good approximation, the assumption of equilibrium

controlled desorption is conservative; that is, predictions based on the equilibrium assumption will overestimate leachate contaminant concentrations for

dredged material. The equilibrium assumption is conservative because interphase transfer is from the dredged material solids to the pore water, and

equilibrium means that all of the desorption that can occur has occurred.

Thus, for clean water entering the dredged material, pore water contaminant

concentrations cannot be higher than the equilibrium value.

34
MASS FlUX

OUT

D 2 A- c1 BC - B Ct

1 (1)

s = Pb8i(2)

n xt

where

Dp- dispersion coefficient for ith contaminant, m2

/sec

C1 - pore water concentration of ith contaminant, mg/f

z - space dimension, m

V - average pore water velocity, in/sec

t - time, sec

S - interphase contaminant transfer, mg/f sec

Pb " bulk density, kg/f

n - porosity, dimensionless

-• solid phase concentration of ith contaminant, mg/kg

Figure 2. Mathematical model of dredged material leaching

(from Hill, Myers, and Brannon 1988)

35
METHODS

Oxidized Sediment Preparation

Sediment used in aerobic testing was first placed into 38-1 glass aquarium to a depth of approximately 6 cm. The sediment was allowed to oxidize at

ambient temperature. Each week the sediment was thorouyhly mixed to expose

fresh sediment surfaces to the air. When necessary, distilled-deionized (DDI)

water was added to the sediment to maintain the original moisture condition.

At the end of six months, the sediment was again thoroughly mixed before being

used in testing.

Anaerobic sediment Preparation

Anaerobic sediments were maintained in sealed containers under refrigeration at 4 °C. All sample handling and manipulation was conducted in a glove

box under a nitrogen atmosphere to preclude sediment oxidation.

Batch Testing

A 4:1 water-to-sediment ratio and a shaking time of 24 hr were used in

the sequential batch leach tests. General test procedures for assessing

steady-state leachate and sediment metal and organic contaminant concentrations are detailed in Table 1. Sequential batch tests for metals under anaerobic conditions were conducted in triplicate 250-ml polycarbonate centrifuge

bottles with leakproof caps. Each centrifuge bottle was loaded under a nitrogen atmosphere with anaerobic sediment and deoxygenated DDI water. Tubes were

mechanically shaken, then centrifuged at 13,000 x g for 30 min. Most of the

leachate from each 250-ml centrifuge bottle was filtered through a 0.45-pm

membrane filter. The unfiltered leachate was analyzed for pH using a combination electrode and a millivolt meter, and for conductivity using a Yellow

Springs Instrument Company conductivity meter and cell. Fresh deoxygenated

DDI water was added to replace the leachate removed for analysis. The procedure described above for sequentially contacting anaerobic sediment with clean

water was repeated seven times. The same general procedure was repeated for

aerobic batch leach tests for metals, except that anaerobic conditions were

not maintained.

Testing of sediment for organic compounds was conducted as described for

metals except that 450-ml stainless steel centrifuge tubes double-rinsed with

acetone were used. Also, the total mass (approximately 350 g) of sediment and

water was adjusted to allow the tube to be safely centrifuged at 6,200 rpm

(6,500 x g). Following shaking, samples were removed from the tumbler and

centrifuged for 30 min. Resulting supernatants were filtered through a

Whatman GF/D prefilter and a Gelman AE filter with a nominal pore size of

1.0 pm. The filters (Whatman GF/D prefilters and Gelman AE filters) are

binderless, glass-fiber containing no detectable organic contaminants. As a

further precaution against contamination, the filters were combusted at 400 "C

prior to use. Filtration was conducted under a nitrogen atmosphere and samples for organic contaminants were acidified with a few drops of Ultrex nitric

acid and refrigerated at 4 °C in acetone-rinsed 2-2 glass bottles until analyzed. A subsample of filtered leachate was set aside from both the anaerobic

and aerobic tests for analysis of total organic carbon. After each cycle, the

sediment was remixed with DDI water, shaken for 24 hr, and then processed as

36
TABLE 1. TEST SEQUENCE FOR SEQUENTIAL BATCH LEACHING OF ANAEROBIC

SEDIMENT FOR ORGANIC CONTAMINANTS AND METALS

Step 1. Load sediment into appropriate centrifuge tubes; 250-ml polycarbonate

for metals and 450-mi stainless steel for organic contaminants. Add

sufficient water to each tube to bring final water-to-sediment ratio

to 4:1. Load sufficient number of stainless steel tubes to obtain

sufficient leachate for analysis.

Step 2. Place centrifuge tubes for metals on reciprocating shaker and shake

at 160 cycles per minute. Place centrifuge tubes for tributyl TIN

and PAHs in rotary mixer and turn at 40 revolutions per minute.

Step 3. Centrifuge for 30 min at 6,500 x g for organic contaminants and

13,000 x g for metals.

Step 4. Filter leachate through 0.45-pm membrane filters for metals or

through WHATMAN GD/F glass-fiber prefilters followed by GELMAN AE

glass-fiber filters of 1.0-pm nominal pore size for organic contaminants. Set aside a small amount of leachate prior to acidification

for analysis of pH, conductivity, and TOC.

Step 5. Return to Step 2 after replacing leachate with deoxygenated-distilled

water. Repeat the entire procedure the desired number or times.

Notes: Testing sequence is the same for aerobic sediments except that

anaerobic integrity is not maintained.

previously described. Three replicates were taken through six leach cycles

for the anaerobic and aerobic testing.

Column Leach Testing

Column leaching tests were conducted in divided-flow permeameters

designed to minimize wall effects and provide for pressurized operation

(Figure 3). The inner permeameter ring divides flow, separating the leachate

flowing through the center of the column from that flowing down the walls,

thereby minimizing wall effects on leachate quality. The applied pressure

forcrs water through the sediment at rates sufficient to allow sample collection in a reasonable period of time.

Sediment was loaded into the permeameters in several lifts having an

average thickness of 5 cm, the number of lifts added depend on the total sediment thickness desired. As each lift of water-saturated sediment was added,

the permeameter was vigorously agitated on a vibrating table to remove trapped

air. The weight and height of each lift were measured and recorded following

vibration. Sediment height averaged 18 cm for metal and 36 cm for organic

37
fPRESSUREOINLET

TOP PLATE 

INESSR PR T

-7}

NEOPRENE 0 RINGS

Figure~~~ 3.Divde-flw eacin.co.. 9J em. - A GAKE

OUTER " • ", -' LJ' OUE 

OUTE OULET •.....,,.NMER OUTLETOUEOTE

Figure 3. Divided-flow leaching column

contaminant analysis. A greater depth of sediment was needed for organic

analysis because a greater sample volume was needed for chemical analyses.

Sediment pore volume was determined by measuring the total weight and volume

of sediment added to the permeameter and then the weight and volume of sediment samples before and following oven drying at 1050 C; weight loss upon drying was then equated to the volume of water in the permeable voids. Next, the

void volume for the sediment column above the inner ring of each permeameter

was determined. Therefore, pore volumes eluted refer to the column of water

filled voids above the permeameter inner ring.

Following sediment addition, distilled, deionized water was added to the

permeameters; the apparatus was sealed and pressurized with either nitrogen or

air depending on whether the test was conducted on anaerobic or aerobic sediment, respectively. Periodic addition of water was necessary during the

course of a test. Effluent from the inner and outer permeameter rings was

drained through teflon tubing into 1,000-ml graduated cylinders. The cylinder, receiving flow from the inner outlet of each permeameter, was isolated

from the atmosphere by a water trap that allowed gas used to pressurize the

permeameters to escape without exposing the leachate to the atmosphere. The

collection cylinder head-space was purged with nitrogen prior to testing

anaerobic sediment.

Effluent flow from the permeameters was regulated by adjusting the operating pressure. The permeability of sediments generally decreased for the

first 2 weeks of operation. As permeability decreased, operating pressure was

increased to maintain a constant flow. Permeameter flow generally stabilized

38
after 2 weeks of operation. A daily record was maintained of operating pressure and flow from both the inner and outer rings of the permeameter.

Leachate samples for metals and organic contaminants from anaerobic sediment

were filtered under nitrogen using procedures previously described for batch

testing.

Data and Statistical Analysis

All statistical analyses were conducted using methods developed by the

Statistical Analysis Systems Institute (Barr et al. 1976). To test for

differences between means, analysis of variance procedures were used.

RESULTS AND DISCUSSION

Sequential batch tests have been applied to estuarine and freshwater

sediments (Environmental Laboratory 1987; Myers and Brannon 1988b; Brannon et

al. 1989; Palermo et al. 1989; Brannon, Myers, and Price 1990). Results of

sequential batch leaching of contaminants are strongly affected by the salinity of the sediment being tested. Sediments from saline environments possess

high pore water concentrations of anions and cations such as sodium, chloride,

potassium, and sulfate that increase the ionic strength of pore waters and

leachate. As sequential batch leaching with fresh water proceeds, the ionic

strength of the freshwater leachate remains relatively constant, but the ionic

strength of leachate from saline sediments decreases (Brannon et al. 1991).

In the following paragraphs, typical results from estuarine (saline) and

freshwater sediments are presented.

Freshwater Sediments

Cadmium and zinc (Zn) desorption isotherms (sediment concentration (q)

versus leachate concentration (C)) prepared from anaerobic sequential batch

leach tests conducted on freshwater sediment from Indiana Harbor, Indiana

(Environmental Laboratory 1987) are shown in Figure 4. These desorption isotherms are well defined and follow the theory for constant K., where Kd is the

slope of the isotherm.

Anaerobic sequential batch leaching for polychlorinated biphenyls (PCBs)

in Indiana Harbor sediment produced clustered desorption isotherms that did

not show in Figure 5 a well-defined trend (Environmental Laboratory 1987).

The insert in the upper right-hand corner of Figure 5 shows that when plotted

with the graph origin at the point 0,0 the data reduce to a dot. For clustered desorption isotherms, Kd is the single point distribution coefficient

with the centroid of the cluster as the point q,C. Although the desorption

isotherm is clustered, the distribution coefficient is interpreted as a

constant.

Results of other sequential batch leach tests on anaerobic freshwater

sediments have shown the classical desorption indicated in Figures 4 and 5

(Brannon et al. 1989; Brannon, Myers, and Price 1990; Myers 1991). In general, distribution coefficients for metals are small, usually less than

10 2/kg, and the fraction of metal resistant to aqueous leaching is large,

usually greater than 99 percent of the bulk metal concentration. The distribution coefficient for PCBs in freshwater sediments is constant and usually

greater than 1,000 2/kg, and the fraction resistant to leaching is usually

assumed to be zero.

39
4130 I

ZINC

i- 4125

2

4120

2 4115 - 0l

!Z

Z

z

0 4110

0 0 0.25 0.50 0.75 1.00 1.25 1.50

ZI--

z

I~J

• 20.1

CADMIUM

h 20.0

U 19.9 w

19.8

LEGEND

- m ANAEROBIC LEACHING

19.7 I I I I

0 0.002 0.004 0.006 0.008 0.010 0.012

AVERAGE STEADY STATE LEACHATE CONCENTRATION, jLg/ml

Figure 4. Desorption isotherms for zinc and cadmium

in Indiana Harbor sediment

40
1.5 -

3.4999

3.4998 0

U U 0 0.001

3.4997

3.4996-

3.4995 -

3.4994 -

3.4993 - U

3.4992 -

3.4991 -U

3.4990 U

34989 I I i I I

0 0.00002 0.00004 0.00006 0.00008 0.00010 0.00012

C,pg/rH

Figure 5. Desorption isotherm for 2,2',4,4'-tetrachlorobiphenyl

for anaerobic leaching of Indiana Harbor sediment

41
Estuarine Sediment

Arsenic and nickel concentrations in anaerobic sequential batch leachate

from Everett Bay, Washington, sediments as a functicn of sequential leach

cycle number are shown in Figure 6. Arsenic and nickel concentrations were

low initially, peaked at either the third or fourth leach cycle, then

declined. The arsenic and nickel desorption isotherms prepared from the data

in Figure 6 are shown in Figure 7. Initially, the isotherm slopes for these

elements were negative; that is, leachate metal concentrations increased as

the bulk sediment metal concentrations decreased. After, the third or fourth

leaching cycle, the isotherms form changed to a classical form.

60

LEGEND

50 -

As

/1 \ Ni4

z

6 40

I

z

20 -

z/

20 T

10 -

0 I I I I I I I I

0 1 2 3 4 5 6 7 8 9

SEQUENTIAL LEACH NUMBER

Figure 6. Arsenic and nickel concentrations in anaerobic sequential

batch leachate for Everett Harbor sediment

In some studies of estuarine sediments, slopes of metal desorption isotherms have been negative through the entire leaching sequence (Figure 8). A

turning point was never reached, although a turning point must exist; otherwise, the desorption isotherm will intersect the abscissa. This result is a

physical impossibility because it implies that a clean sediment can leach

contaminant. In the limited testing conducted thus far, these types of

desorption isotherms have been found only for estuarine sediments.

Figure 9 shows a PCB desorption isotherm prepared from anaerobic sequential batch leach tests conducted on sediment from the New Bedford Harbor

Superfund Site, New Bedford, Massachusetts, (Myers and Brannon 1988b). This

desorption isotherm indicates nonconstant Kd during sequential leaching. Nonconstant PCB partitioning during sequential leaching has recently been related

42
ARSENIC 5.2200 I 1 1 I 1 1

E

z

2F

0

-REPI

zo

U5.2200 - _ 

0

C(a) C, LE•HAT CONENTRTIONEND/

z

S20.85 -- REP 1 -

,. D--0 C REP 2

in 0-9REP 3

a 0- OREP 4

5.2200 _ I 1 

0 0.0093 0.0186 0.0279 0.0371 0.0464 0.0557 0.0650

C, LEACHATE CONCENTRATION, mg/I

(a)

NICKEL

21.33

E

0

tR 21.09

Iz

Lii

z

0 LEGEND

0

I-20.85aRE1

z

U)

20.610.008 0.018 0.027 0.037 0.046 0.056 0.065 0.075

C. LEACHATE CONCENTRATION, mg/I

(b)

Figure 7. Arsenic (a) and nickel (b) desorption isotherms

for Everett Harbor sediment

43
0IIM 02 I I I I I I I II

E

z

0

-0 S3010 

z

0

- 3000

z

- 2990

0- 2980 (n 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

STEADY-STATE LEACHATE CONCENTRATION, mg/I

Figure 8. Desorption plot for Zn from anaerobic sequential

batch testing of New Bedford Harbor sediment

N.

o1 29.60 I

E

z

_o 6

Iz

W

O 29.55 z

0

0- 0

Iz

W

.La

Cv 29.50 -

I--I

P- 29.46 V 0 0.005 0.010 0.015 0.020

STEADY-STATE LEACHATE CONCENTRATION, mg/I

Figure 9. Desorption isotherm for PCB congener 118 from sequential

batch leaching of New Bedford harbor sediment

44
to salt washout and subsequent deflocculation of colloidal sediment organic

carbon containing PCBs (Brannon et al. 1991). As previously discussed,

deflocculation of colloidal sediment organic carbon refers to release of

organic carbon associated with sediment. The overall result is an elution

curve that has a distinct peak in leachate PCB concentrations that occurs

after the first four leaching cycles. This same effect has been observed in

other studies (Brannon et al. 1989).

Sediment Oxidation Status

Sediment oxidation status exerts pronounced effects on metals leaching

from most saline sediments, e.g., Baltimore Harbor sediment (Figure 10). In

saline sediments high in sulfur and low in carbonate, leachate pH generally

shows a marked decrease following 6 months of oxidation (Figure lOa). In

addition to the drop in pH brought about by sediment oxidation, leachate sulfate concentration increased by an order of magnitude because of oxidation of

sulfur and sulfide compounds in the anaerobic sediment (Figure lOb). As

sequential batch leaching progressed, leachate pH increased and sulfate concentrations decreased in the aerobic leachate. Aerobic conditions resulted

in much higher concentrations of Zn in the leachate than anaerobic conditions

(Figure lOc). During the course of sequential batch testing, 7.7 percent of

sediment Zn was lost under aerobic conditions compared to 0.4 percent under

anaerobic conditions. These results are illustrative of the effects that

sediment oxidation can exert on metal leachate concentrations.

Column Testing

Sequential batch leach tests, useful for determining desorption kinetics, equilibrium distribution coefficients, and long-term leaching characteristics, cannot simulate advective-dispersive and other mass transfer effects

occurring in CDF's. Column leach tests are used as laboratory scale physical

models of contaminant elution from dredged material that include advectivedispersive and other mass transfer effects. An integrated approach is used to

examine the applicability of source terms formulated on the basis of sequential batch leach data to contaminant transport in porous media. In the integrated approach, parameters from sequential batch leach tests, soils tests,

and column operating records are used in a contaminant transport equation to

predict column elution histories. Predictions are then compared to observed

elution behavior. If predicted and observed behavior agree, the conclusion

may be reached that the processes governing transfer of contaminants from

dredged material solids to water have been adequately described. If not,

other source term formulations may be needed. Once interphase transfer has

been adequately described, contaminant migration by leaching can be evaluated

for the flow conditions that apply in the field.

To date, column leaching studies have been conducted on sediments from

Indiana Harbor, Indiana (Environmental Laboratory 1987), New Bedford Harbor,

Massachusetts (Myers and Brannon 1988a), and Everett Harbor, Washington (Palermo et al. 1989). The major problems encountered in using the divided-flow

column leaching apparatus were the number of pore volumes that could be eluted

and the potential for sample deterioration during collection.

45
9a. pH

7

S6 0

5 C •0 AEROBIC

4 0 ANAEROBIC

3 I I I I 1

0 1 2 3 4 5 6 7 8

b. Sulfate concentration 5000I I I I I

•04000 0- AEROBIC . 0• ANAEROBIC

J 3000

z

0

• 2000

< 1000

0

0 1 2 3 4 5 6 7 8

c. Zinc Concentration

4 .0 I I I I I

0 AEROBIC

-3.02 0 ANAEROBIC

2.5 -

Z 2.0 0

0

U 1.0

z

N 0.5 -

0.0 . 0 1 2 3 4 5 6 7 8

LEACH CYCLE NUMBER

Figure 10. Relationship between oxidation state in

Baltimore sediment and leachate

46
Freshwater

Anaerobic column leach tests conducted on Indiana Harbor sediment

indicated that a source term based on contaminant specific constant Kd adequately described observed elution curves for metals and PCB's (Environmental

Laboratory 1987). Figure 11 shows predicted and observed column elution

curves for PCBs from Indiana Harbor sediment. The column leach tests also

showed that the sequential batch leach test overestimated metals and PCB

concentrations in column leachates and was, therefore, a conservative estimator of leachate quality for Indiana Harbor dredged material.

0.0006 PREDICTED

W/DESORPTION

0.0005

,,,PREDCTED

V~-~W10 DESORPTION

0.0004 -

N\

E

S0.0003

PEREEAMETER NO.4

0

-0.0002 - PERMEAMETERS

PERAVEAMETER NO. 4

0.0001 - EEAEENO6

PERMEAMETER NO.5

0

0 2 4

PORE VOLUME

Figure 11. Total PCB concentrations in anaerobic column

leachate for Indiana Harbor sediment

The prediction shown in Figure 11 was developed using a semi-infinite

analytical solution to Equation 1 (see Figure 2) with constant Kd. Sequential

batch leach tests on other freshwater sediments indicate that source term

formulations based on constant Kd will probably describe contaminant leaching for fresh water sediments (Brannon et al. 1989, Myers 1991). However,

Indiana Harbor sediment is the only freshwater sediment that has been investigated in column leaching studies. Furthermore, only four pore volumes were

eluted. Operational limitations of the columns prevented collection of more

data. Elution of the volume of sample needed for PCB analysis required several months, and elution of additional pore volumes would have extended the

period of data collection to beyond the scope of the study. An improved column design that overcomes these limitations is currently being evaluated.

Aerobic column leaching studies were also conducted on aged Indiana

Harbor sediment. These studies were largely unsuccessful because the residual

oxygen demand in the sediment converted "aerobic" columns to anaerobic columns

47
shortly after they were flooded (Environmental Laboratory 1987). Since aerobic batch and column leach tests were not conducted under equivalent redox

conditions, source term formulations developed from aerobic batch tests were

not applicable to "aerobic" columns. Application of the integrated approach

to partially oxidized sediment was, therefore, inappropriate because the

assumption of equivalent redox conditions could not be maintained.

Estuarine Sediment

Everett Harbor

Results of sequential batch leaching of Everett Harbor sediment differed

sharply from results for Indiana Harbor sediment. Leachate contaminant concentrations were lower and release of contaminants during anaerobic sequential

batch leach testing did not follow the classical desorption behavior observed

for Indiana Harbor sediment. Column leaching studies on Everett Harbor sediment could not confirm or refute the trends observed in sequential batch leach

tests because column operational limitations prevented elution of a sufficient

number of pore volumes.

The permeameter elution curve for cadmium in leachate for anaerobic

Everett Harbor sediment was not carried far enough to compare to elution

trends observed in the sequential batch leach test (Figure 12). The number of

pore volumes needed for comparison were not eluted because, as previously

discussed for Indiana Harbor sediment, to do so would have extended the period

of data collection beyond the scope of the study. Furthermore, the predicted

curve in Figure 12 is based on equating each cycle in the sequential batch

test to elution of an equivalent number of pore volumes; that is, Equation 2

with a source term was not used. To predict column leachate concentrations

using Equation 2 was impossible because the desorption isotherms from the

sequential batch leach tests showed nonconstant partitioning and source term

formations for this type of partitioning are not available.

Aerobic column leaching studies were also conducted on aged Everett

Harbor sediment. Residual sediment oxygen demand, as previously discussed for

Indiana Harbor sediment, made application of the integrated approach inappropriate (Palermo et al. 1989).

New Bedford Harbor

Leach tests conducted on anaerobic New Bedford Harbor sediment showed that

desorption theory based on contaminant specific constant Kd did not adequately described leaching of metals or PCB's in either batch or column leach

tests (Myers and Brannon 1988b). Desorption isotherms showed the nonconstant

partitioning previously observed for Everett Harbor sediment. Sequential

batch leach *L..ta indicated that maximum leachate contaminant concentrations

would not occur until after several pore volumes were eluted. Therefore, the

time period for data collection from column leach tests was extended for

New Bedford Harbor sediment relative to the data collection periods used for

Indiana Harbor and Everett Harbor sediments.

Column leachate PCB data for anaerobic New Bedford Harbor sediment

showed complicated elution curves in which concentrations first tended to

decrease and then increase to peak values after about three pore volumes had

48
30

LEGEND

0 - SEQUENTIAL BATCH DATA

S20 --- • PERMEAMETER D•AT

0

20

0 2 4 6 8 10 12 14 16 18 20

PORE VOLUMES

Figure 12. Comparison of observed and predicted cadmium

concentrations in leachate from anaerobic

permeameters for Everett Harbor sediment

been eluted. These trends are illustrated for aroclor 1242 in Figure 13. The

decrease in concentrations from initial values corresponded to the period in

which electrical conductivity rapidly decreased, and the increase to peak

concentrations corresponded to the period following development of lower,

relatively constant electrical conductivity in column leachate. More than a

year was required to elute the six pore volumes shown in Figure 13.

Although predicted and observed curves are not shown in Figure 13, the

shape of the observed PCB elution curve is in agreement with the shape predicted from sequential batch leach tests (Myers and Brannon 1988b). The PCB

concentrations in column leachate, however, were significantly lower than in

the batch leachates. Several explanations for concentration differences

include loss of contaminants by sorption to collection vessels during extended

periods of leachate collection, particle disaggregation effects related to

differences in hydraulic regimes in batch and column leach tests, and the

inability to elute more pore volumes. Any of these factors may have precluded

Scovery of true peak concentrations at higher pore volumes. An improved

. umn design that overcomes some of these problems is currently being evaluated (Myers, Gambrel1, and Tittlebaum 1991). Additional column leaching

studies on estuarine sediments with elution of more than six pore volumes is

needed to verify the correlation of contaminant elution curves with changes in

electrical conductivity observed in the New Bedford Harbor study.

Aerobic column leaching studies were also conducted on aged New Bedford

Harbor sediment. Residual sediment oxygen demand, as previously discussed for

Indiana and Everett Harbor sediments, made application of the integrated

approach inappropriate.

49
0.020 1 I 1 I 

LEGEND

8 REPLICATE 1

0.015 * REPLICATE 2 A REPLICATE 3

0'

E

- 0.010-

0-J

0

0.005-

0.001-

0 2 4 6

PORE VOLUMES

Figure 13. Aroclor 1242 concentration in column leachate

from anaerobic New Bedford Harbor Sediment

50
SUMMARN A,.3 CONCLUSIONS

In the leaching studies conducted to date, each sediment has provided

unique leachate quality data. A source term based on contaminant specific

constant Kd adequately described observed elution curves for metals and PCB's

in freshwater Indiana Harbor sediment. Sequential batch leach tests in

Indiana Harbor sediment overestimated metals and PCB concentrations in column

leachates and was, therefore, a conservative estimator of leachate quality for

Indiana Harbor dredged material.

Sequential batch leaching of saline Everett Harbor sediment did not

follow the classical desorption behavior observed for freshwater Indiana

Harbor sediment. Desorption isotherms showed nonconstant partitioning for

which source term formulations are not available. Similar nonconstant partitioning was observed in saline New Bedford Harbor sediments. Batch leaching

curves could not be validated for either saline sediment because of the limited number of pore volumes (4-6) that could be eluted from the columns.

Changes in sediment redox conditions and sediment initial salinity have

been shown to strongly influence leachate quality. Sediment aged to simulate

development of an aerobic crust tends to release metals, whereas anaerobic

sediments tend to retain metals. The pH changes associated with oxidation of

sediments are believed to be the underlying cause of increases in metals

mobility. Furthermore, estuarine and freshwater sediments behave differently.

Desorption isotherms for contaminants in freshwater sediments tend to follow

classical sorption theory, whereas, isotherms for estuarine sediments are

unlike any previously reported. Sediment organic matter and the tendency to

release sedimexrt organic matter as salts are leached are believed to be the

underlying factors causing differences in results between freshwater and

estuarine sediment.

REFERENCES

Bahr, J. M., and Rubin J. 1987. "Direct Comparison of Kinetic and Local

Equilibrium Formulations for Solute Transport Affected by Surface Reactions,"

Water Resources Research. Vol 23, No. 3, pp 438-452.

Barr, A. J., Goodnight, J. H., Sall, J. P., and Helwig, J. T. 1976. "A

User's Guide to SAS 76," SAS Institute, Inc., Raleigh, NC.

Brannon, J. M., Pennington, J. C., Myers, T. E., and Price, C. B. 1989.

"Factors Affecting Leachate Quality," Environmental Effects of Dredging Notes

EEDP-02-11, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Brannon, J. M., Myers, T. M., and Price, C. B. 1990. "Factors Affecting the

Behavior of Metals in Leachate," Environmental Effects of Dredging Notes EEDP02-13, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Brannon, J. M., Myers, T. E., Gunnison, D., and Price, C. B. 1991. "Nonconstant Polychlorinated Biphenyl Partitioning in New Bedford Harbor Sediment

During Sequential Batch Leaching," Environmental Science and Technology.

Vol 25, No. 6, pp 1082-1087.

51
Environmental Laboratory 1987. "Disposal Alternatives For PCB-Contaminated

Sediments From Indiana Harbor, Indiana, Volume II," Miscellaneous Paper EL-87-

9, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Hill, D. 0., Myers, T. E., and Brannon, J. M. 1988. "Development and Application of Techniques for Predicting Leachate Quality in Confined Disposal

Facilities: Background and Theory," Miscellaneous Paper D-88-1, US Army Engineer Waterways Experiment Station, Vicksburg, MS.

Jennings, A. A., and Kirkner,J. J. 1984. "Instantaneous Equilibrium Approximation Analysis," Jgurnal of Hydraulic Engineering. Vol 110, No. 12,

pp 1700-1717.

Myers, T.E., and Brannon, J. M. 1988a. "New Bedford Harbor Superfund Project, Acushnet River Estuary Engineering Feasibility Study of Dredging and

Dredged Material Disposal Alternatives; Report 5, Evaluation of Leachate

Quality," Technical Report E-88-15, U.S. Army Engineer Waterways Experiment

Station, Vicksburg, MS

Myers, T. E., and Brannon, J. M. 1988b. "Synthesis of Leaching Research and

Workshop Results," Environmental Effects of Dredging Technical Notes, EEDP02-7, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Myers, T. E. 1991. "Polychlorinated Biphenyl Levels in the Saginaw Confined

Disposal Facility During Disposal Operations, Fall 1987," Miscellaneous Paper

EL-91-4, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Myers, T. E., Gambrell, R. P., and Tittlebaum, M. E. 1991. "Design of an

Improved Column Leaching Apparatus for Sediments and Dredged Material,"

Miscellaneous Paper D-91-3, U.S. Army Engineer Waterways Experiment Station,

Vicksburg, MS.

Palermo, M. R., Shafer, R. A., Brannon, J. M., Myers, T. E., Truitt, C. L.,

Zappi, M. E., Skogerboe, J. G., Sturgis, T. C., Wade, R., Gunnison, D.,

Griffin, D. M., Jr., Tatum, H., Portzer, S., and Adamec, S. A. 1989. "Evaluation of Dredged Material Disposal Alternatives For US Navy Homeport At

Everett, Washington," Technical Report EL-89-1, U.S. Army Engineer Waterways

Experiment Station, Vicksburg, MS.

Valocchi, A. J. 1985. "Validity of the Local Equilibrium Assumption for Modeling Sorbing Solute Transport Through Homogeneous Soils," Water Resources

Research, Vol 21, No. 6, pp 808-820.

52
PREDICTION OF SURPLUS WATER DENSITY

AT RECLAMATION SITE

Takeo Maekawa

Japan Dredging and Reclamation Engineering

Association

2-8, Toranomon 1-chrome, Minato-ku, Tokyo

ABSTRACT

When a land is reclaimed using pump-dredging

soils, fluid is poured into the landfill site together

with earth and sand, giving rise to the problem of

surplus water. When land reclamation works approach

their end, muddy water overflows the site because of

its limitation of volume. In recent years, regulations have been enforced to control effluent from

reclaimed lands to prevent water pollution and protect

environments, and such surplus water should be disposed properly, according to established standards.

In order to work out an effective plan for surplus

water disposal, it is necessary to know the behavior

of surplus water, especially the changes in its density that take place in accordance with the progress

in reclamation works. No noticeable researches have

been done on this subject, and there is no established

method to work out a disposal plan. With the purpose

of casting a light on this problem, a reclamation site

related to an actual engineering work was surveyed to

study to behavior of surplus water; on the basis of

findings on the spot, tests using a water tank model

were conducted top examine the accuracy of reproducibility of onsite conditions.

During the on-the-spot survey, the emphasis of

study was placed on the relations between residence

time and density of slurry inflow and the grading of

turbidity components. for model tests, survey results

were taken as the prototype and conformity with the

prototype regarding the Frouds Law, and water area

load was considered as basic law of similarity. The

size of the model was set in a scale of I to 30 in

horizontal length (Lr - 1/30) and I to 10 in vertical

length (Hr - 1/10). The following findings were made

as the result of the survey and model tests:

A. On-the-spot survey

(1) Under the conditions of landfill-site area of

27,600 mi2 , resident volume of 1-m water depth

and inflow of 760 m3/hr, the shortest resident flow distance stood at 226 m and resident time at 51 min. The water depth was

53
measured by depth sounding. The water content ratio of soils at the position was

300 to 350 percent.

(2) Average suspended solids (SS) of slurry

inflow at the site stood at 115,500 mg/1

(70,000-200,000 mg/I), that of slurry at the

point 30 m from the sludge outlet at

20,000 mg/I (8,000-41,000 mg/I) and that of

surplus water outflow at the spillway was

50 mg/I (13-181 mg/I). The removal rate of

slurry inflow near the sludge outlet was 82.8

percent against 99.96 percent at the spillage

outlet, indicating that the most of soil

grains settle down near the sludge outlet.

(3) As to the grading, slurry inflow contained

8 percent of sand, 89 percent of silt, and

3 percent of clay (of which colloids

accounted for 2.7 percent). Particles of

less that 20 pm amounted to 90 percent of all

particles contained in the slurry near the

sludge outlet, with the average of 4 to 5 pm.

Similarly, 90 percent of particles contained

in surplus water outflow were less than 20 pm

with the average standing at 3 to 4 pm,

showing that these particles were a little

finer than those near the sludge outlet.

k. Model tests

(1) The tests indicated an average surplus water

SS density of 173 mg/I (136-218 mg/I) against

the prototype's average of 50 mg/I (14-

18 mg/I), showing a difference of about

120 mg/I.

(2) Particles of more than 10 pm accounted for

20 percent of all particles contained in the

surplus water of the prototype, while the

model tests showed the size group occupied

only 5 percent. The probable reason was the

refloating of soil particles at the spillway

of the prototype. Model tests in general

showed greater distribution of finer grains

than in the prototype.

(3) As to the sedimentation removal rate by particle size, the prototype showed no remarkable changes for size groups, indicating the

rate of more than 99 percent for all groups.

In the model tests, the size group of more

than 10 pm showed a rate of nearly 100 percent , but finer size groups indicated various trends, the 2-to 10-m group showing a

54
gradual decrease, the 0.8- to 2-pm group a

gradual increase, and the 0.4- to 0.8-pm

group a gradual decrease. Overall, the

removal rates in model tests were lower by

2 to 5 percent than those of the prototype.

PREFACE

It is often the case with a land reclamation using pimp-dredged soils

that the quality of surplus water deteriorates as the reclamation works progress and on the final stage of reclamation, muddy water of high density flows

out of the reclamation site because of its limited volume. The emphasis of

study on the volume of a landfill site is usually placed on the rate of change

in the volume of disposed soils. When the quality of surplus water is taken

into consideration, however, it is necessary to give a free volume to the

site. It is also important to grasp and predict the relationship of accumulation of soils with the quality of surplus water, especially its density of SS,

in order to make timely treatment of the surplus water to meet the discharge

standards.

Analysis of the numerical model and model tests are considered to be

useful for prediction of surplus water density at a reclamation site. In

either case, it is necessary to compare the results with the results of onthe-spot investigation and to examine their reproducibility. Data concerning

this subject are insufficient at present; therefore, a reclamation site

related to an actual engineering work was surveyed to collect data on changes

in water quality. On the basis of the findings, tests using a water tank

model were conducted to grasp the accuracy of reproducibility of onsite

conditions.

During the survey, the relationship between the residence time of slurry

inflow and the density of outflow and the grading of turbidity components were

taken up for probing. In model tests, survey results were takes as the prototype, and conformity with the prototype regarding the Frouds Law and water

area load was considered as basic law of similarity; a model of a scale of

horizontal length (1/30) and vertical length (1/10) was used, and the accuracy

of reproducibility of surplus water was confirmed. This report introduces the

results of the survey and model tests.

ON-THE-SPOT SURVEY

This survey was conducted to grasp the relationship between the residence time of slurry inflow and density of surplus water outflow and the grading of turbidity components at a reclamation site. The reclamation site was

created for disposal of dredged soils coming from dredging works in Hakata

Port, Kyushu District, to develop a channel and a berth.

Subject Engineering Work

The subject of this survey was the dredging work aimed at the development of a channel extension and a berth, which was intended to be one of the

two berths planned at the public wharf (-12 m), shown in Figure 1, but was to

be opened for the time being as a wharf of 9 m in depth.

55
Hakozabk

b rea kwa t e r

Ea s t b r eakwa t e r N

Dred g i ng a rea

. . . . I_ -• ... . . . . ...

- J -. . .

(W a Y

Reclamation si to H a k o z a k i h% a r f

at Hakozaki Wharf

Figure 1. Plotting of reclamation site

The planned volume of dredged soils was 129,500 m3, and dredging was

being done by a special pump (oozer pump) dredge. Dredged soils were disposed

of at a landfill site near the dredging area.

As shown in Figure 2, a part of the existing wharf was partitioned by a

steel pipe sheet pile, and an embankment 2.5 m high was raised along the edge

of the partitioned wharf apron. The area of the reclamation site was

27,600 i 2 with the volume of 237,000 M3 . Figure 3 gives a complete view of a

disposal area.

The spillway consisted of a weir with stop log, a sedimentation basin,

and an outlet basin. Surplus water was sent out of the outlet basin by four

discharge pipes (0610 im/) into the open sea. For the treatment of surplus

water, equipment was set up near the stop log weir to add inorganic or organic

coagulant to surplus water. The outlets of the discharge pipes in the open

sea were encircled by two nets of pollution prevention membrane. The ceiling

of surplus water density was set at SS 60 mg/I at points near the outside net

of pollution prevention membrane.

At the time of the survey, a sand pipe (0560 m/m) was set up on land

extending from the fixed point to the sludge outlet located on the west side

of the reclamation site. Coagulant was not added to surplus water at that

time.

Outline of Survey

Cases of Survey

The survey was conducted four times, as shown in Table 1.

56
. -•._------_----_--- C 

.,,....

0- C• .~o . ...

Fiur 2. Pla of relUto sit

............

I- -A

Figure 2. Plan of reclamation site

Figure 3. Complete view of disposal area

57
TABLE 1. CASES OF SURVEY

Accumulated Volume of Dredged

Case Soil at the Time of Survey

Case-A 90,500 M3

Case-B 97,150 m3

Case-C 99,658 m 3

Case-D 105,233 mi3

Items of Survey

Soils dredged up with water are carried by a sand pipe to the sludge

outlet and discharged in to the landfill site. Of the earth and sand discharged into the site, most of the crude particles settle down around the

sludge outlet together with some of finer particles forced to settle through

hindered settling or other phenomena. Particles unable to settle down here

spread out throughout the site and flow through resident channels toward the

spillway, some of them going out of it with surplus water.

Efforts were made during this survey to grasp turbidity not only in

degrees or as total SS volume but as SS grading of muddy surplus water at the

following three different points. The points are also shown in Table 2 with

the items of survey.

TABLE 2. ITEMS OF SURVEY

Point of Survey Items of Survey

Time of inlet

Inlet point

(Sludge outlet) Inflow

Slurry inflow Water content, grading

Resident flow Soil accumulation Depth, water content

(Within landfill site) Slurry near inlet Turbidity, SS, grading

Time of outflow

Outflow point

(Spillway) Outflow

I Spillway Turbidity, SS, grading

A. Grading of slurry inflow. This effort examined whether dredged

earth and sand are divided into particles and mixed up completely

before being discharged into the reclamation site. when

58
considerably clayey earth and sand are dredged by cutter pump

dredge, the slurry often contains lumps of soils, which may not be

divided into particles. Such lumps may not contribute to turbidity

when discharged into a landfill site. In order to confirm if such

conditions existed, slurry samples obtained near the sludge outlet

were examined by two methods. One of the methods was JISA1204 test

method (names "Shape" method) retained the original conditions of

slurry samples and examined the grading. The results of the two

ways of examination were then compared.

I. Grading of slurry near the sludge outlet. Rates of settling of

floating particles near the sludge outlet or within the radius of

about 30 m from it were examined on the basis of samples of slurry

in this scope and those of slurry inflow, both taken in the same

period.

c. Grading of surplus water outflow. Grading was confirmed of surplus

water overflowing the weir with stop log of the spillway.

Results of Survey

Confirmation of Stability

Adjustment of the Stop log weir was done in the morning and in the

evening. Logs were added in the morning and withdrawn or added in the

evening. Therefore, the outflow of surplus water stopped early in the morning, started again after 3 to 4 hr, and reached a stable state after an additional 2 to 3 hr, maintaining the stability up to the time of adjustment in

the evening.

On the other hand, turbidity of the outflow was low for about an hour

after the start of outflow but tended to become high as the volume of outflow

increased. Later on, turbidity moved downward in Case-A, leveled off in CaseB, and increased further in Case-C. In Case-D, the survey was conducted for

two day s and the turbidimeter's automatic recording indicated a trend of low

to high, then to low, reaching a stable state of quality after 10 hr since the

start of outflow.

On the basis of above data, it was hedged that stability of outflow

volume and water quality was not reached in Cases A, B, and C, and only the

data in Case-D could be utilized as materials for prediction. Samples in

Case-D were taken during the period of *:00 to 15:00 on February 17, and the

resulting values were considered to be representative. Therefore, only the

results of Case-D will be reported below.

Results of the survey on inlet time, the width and height of the weir

with stop log, overflow depth and turbidity in Case-D are shown in Figure 4.

Slurry inflow

The fo'lowing findings were made:

p. Examination, Slurry inflow samples indicated a water content of 420

to 2,320 percent and soil grain specific gravity of 7,607 to 2,651.

59
I.n

I44 - I r 4"- ' .. ... 0

I' * ' -

S... I *I ..

-I*04 I"-

- "-1 -

I I 'II . c.1

S. ' •i 110

.14

t I .q . - 4 . 0 1 - 0

6 0

*lI II' L"2

S... .1 . . . ,I :(U

*.: 4-2

... .. I'! ' 1 04)

, 1! (!

600
I L1 IY

AA

I p Im q 03

K' A II ~61
I i ..

I I *1i I

i r ,I j oy

I'I 4-

i ... . 1 .

lCfl

, Ii 1 0

I+ •+I"Il T '+

I Rl •III l l i i II 
Particle a ize a ccumul at Ion cur a

....... :........:.... ..... ,................. -• -

a .. : = -'.- -- •.. .. *:: 

. -.- . .... 3.:"." -

"3" - ( J I S (salt cal ibra t i o n)

__________'_..._ S: S h a P i _$_-_Z n g _ V e _ t_ h o d

a ot OOl 4.1 1.6

Particle size 0 (mrm)

Figure 5. Particle size of slurry inflow

When converted to SS, they showed the value to 43,520 to

224,540 mg/I.

b. Grading, Results of analysis by different methods are shown in

Figure 5.

Examination

(1) The presupposed phenomenon of clay lumps was not confirmed by

screening using a 2,000 p sieve.

(2) When ne and salt calibration of "JIS method" are compared,

part are finer in the latter case.

(3) Central size group (D5 0) in the case of "JIS method" was

9-13 p. In the case of "Shaping method," it was 7-12 1, and

the greater the volume of soils to be analyzed, the finer

becomes the particles.

(4) The larger size of particles in "JIS method" than in "Shaping

method" is attributable to the secondary cohesion of particles

caused by air drying of samples.

(5) Different methods of analysis showed delicately different compositions of grading, but the average grade distribution of the

slurry inflow was 8 percent of sand, 89 percent of silt, and

3 percent of clay. The "shaping method" used to test this

should be tested under various conditions.

63
Slurry near Sludge Outlet

Additional findings on the slurry follow.

a. Density and grading. The SS of slurry sample was 7,800-40,900 mg/2.

As to the grading, analysis by "Coal-tar counter method" indicated

there was no noticeable difference of particle sizes. There was no

noticeable difference among the cases either, as shown in Figure 6

of each case's particle size accumulation curve.

4 I Nii b emoalratadfot•ation ra t The rtf o set tingS S.oi0l pri

slurr i Figur 7 1e an example o.f grading curves.2 O th

of vaiu sapls th reoa rtof total S D(S voS aroundthe

0 - ' .i ..'1 .' 1 1 .-• 

(74.7-92.7 I".l,',thel and Iflotat~ll~ionlratelatlanlavrageofi3.8peren

SIM .. a ... =.

Figure 6. Average particle size of slurry near sludge outlet

of reclamation site

b.Removal rate and flotation rate. The rate of settling soil particles around the sludge outlet was sought through comparison with

slurry inflow. Figure 7 shows an example of grading curves. On the

basis of these curves and other data concerning density and weight

of various samples, the removal rate of total SS volume around the

sludge outlet was calculated at an average of 86.2 percent

(74.7-92.7) and the flotation rate at an average of 13.8 percent

(7.3-25.3). By size of particle, the percentage of clay around the

sludge outlet was greater than in the slurry inflow, and Figure 7

shows considerable difference in grading characteristics. Even

considering the possibility of errors due to differences in analytical methods, this phenomenon is difficult to understand. Although

the problem of clay remained unsolved, understandable results were

obtained concerning sand, silt, and colloid, with higher removal

rates for greater particle sizes.

64
ig P r 7i C o m s of I at p ar oon tum csuur vi i 

.ynd a slrr nea sldg outle

o:wS I u r r Y I n t .

Fgr7.Cmaioofparticle sizeraergrds s 5sz of s. Wih ur nhepekltowt

5 ,nor al dsturibtinewas d seeliu tedoe o fu15loe2tp

Sp Raemv ratefandloutfloworate.

(1)ne withe rtioein ouflow set ng soiprtic in te rsidw entlo

cogurse was caluae hogomparison eso sur withtce thefluryoron

thelur sludge na outletadothbaiofticluainad

SrlsaerOuthef aacnenigwihlnodniyowapls h ai

Figure 8.

ao and eDensity grading. The SS of surplus water sample was calculated

at 13-181 181 mg/l. Grading (obtained by Coal-tar counter method)

is shown in Figure 9. There was no noticeable difference of

particle size rates regardless of SS sizes. With the peak at 4 to 5 u, normal distribution was seen in the scope of 1.5 to 20 U.

There was a trend that the component ratio of 0.5 to 0.6 ju was a

little higher than normal.

Removal rate and outflow rate,

(1) The ratio of settling soil particles in the resident flow

course was calculated through comparison with the slurry around

the sludge outlet, and on the basis of this calculation and

other data concerning weight and density of samples, the ratio

of removal and the ratio of outflow were calculated as shown in

Table 3. A comparison of particle sizes of slurry near sludge

outlet and surplus water outflow is illustrated in Figure 10.

65
*ISO.

- 60. C

1 IZO.

q- S

8 00.

100.

600

5 5 0 I 1 i 12 15

Figure 8. Outflow volume and SS of water outflow in Case D

(2.17, 0800-1600 hr)

80 1 I

IOU 1OO0

P a rti ClIe S i Ze 0 (UM)

Figure 9. Average particle size of surplus water outflow

66
TABLE 3. RATES OF REMOVAL AND OUTFLOW IN RESIDENT FLOW COURSE

Particle Slurry Near Removal Rate Outflow Rate

Size Sludge Outlet Spillway (%) (%)

(AM) SS Grading SS Grading

(mg/1) rate (%) (mg/I) rate (%) SS Grading SS Grading

406-74 3.1 5.3 99.56 0.44

74-5 19.540 47.5 50 47.6 99.74 99.77 26 0.23

5-1 40.1 34.4 99.74 0.26

less than 1 9.3 12.7 99.66 0.34

(2) The removal rate of total SS volume in the resident flow course

was calculated at 99.74 percent and the outflow rate at

0.26 percent. By size of particle, silt nd smaller particles

showed a tendency of higher outflow rates. Sand of larger size

showed a higher rate of outflow despite its small absolute load

probably due to reflotation of particles in from of the weir.

W t9 - -. ' -i " -

E.-,.v -1 J I • -' IFI i. 

6C u pi I Itu r a i au. 'at 

] -1.12 K! : II I Y1 [ " . .... I T 1:I i!i

III.I1 ...... ll11'I 1. rl I-II i sIII '"-'• 70 I IU S u!rr i Ii nai a gI, ut I1!11I

P0 e 0 : 4rticle [

20 - : I! M I I: I. I I Il I I I I '.11 1 111 ,H : H i '

20 -' 1 1 1 ! 1 i 1 1 1 1 I H I I I 1 1 1 -. 11 1 1"i

I u IOU 100 U

Par ticle silze D J .9iu..

Figure 10. Average particle sizes of slurry near sludge

outlet and surplus water outflow

Summary

The original purpose of this survey was to obtain data on the resident

flow volume corresponding to the initial, middle, and final stages of reclamation and on the relationship between the passage of time and surplus water

67
density. As a result, however, the survey was successful in gathering only

such data as correspond to the final state of reclamation. A summary of the

survey's findings follow:

.. Under the conditions of the reclamation site's water area of

27,600 mz, resident flow volume of 1-m water depth, and inflow of

760 m3 /hr, the shortest resident flow distance stood at 226 m and

the shortest resident time was 51 min, The water depth was obtained

by depth sounding under the earth pressure of 1.8 g/cm red. The

water content of soils at the point was 300 to 350 percent.

k. The SS of slurry inflow into the reclamation site was 115,500 mg/1

(70,000 - 200,000 mg/I); that of the slurry at the point 30 m from

the sludge outlet was 20,000 mg/I (8,000 - 41,000 mg/I); and that of

surplus water outflow at the surplus water outlet was 50 mg/I

13-18 mg/I. The removal rate of slurry inflow near the sludge outlet was 82.8 percent against 99.96 percent at the surplus water

outlet, indicating that the most of soil grains settle down near the

sludge outlet.

•. As to grading, slurry inflow contained 8 percent of sand, 89 percent

of silt, and 3 percent of clay (of which 2.7 percent was colloids).

Particles of less than 20 pm amounted to 90 percent of all particles

contained in the slurry near the sludge outlet, with the average

size (D5 0) of 4 to 5 pm. Similarly, particles of less than 20 Am

accounted for 90 percent in surplus water outflow, with the average

standing at 3 to 4 pm. Generally, particles in surplus water outflow were finer than those of the slurry near the sludge outlet.

WATER TANK MODEL TESTS

For these model tests, the results of the on-the-spot survey introduced

in previous discussions were taken as the prototype, and the accuracy of

reproducibility was confirmed (Case-A). Also, of the various factors of land

reclamation, water depth, density of inflow, and the partition weir and other

devices used to promote settling of particles were taken as parameters to

confirm their qualitative effects on surplus water using a model based on the

reclamation site surveyed (Case-B).

Outline of Tests

Similarity Law of Model

The establishment of a law of similitude between the prototype and its

model is a prerequisite of a successful model test. In handling fluid like

water, the similarity law of Reynolds (R similarity) is applied to the cases

of no free surface as inside a pipe, but the similarity law of Frouds (F similarity) is mainly used for such cases where the influence of free surface is

great as in the cases of harbors. Application of either of the two is problematic in the case of a reclamation site. The use of R similarity will pose

a difficulty concerning the gradient of water surface caused by gravity, while

reproduction of flow regime such as vortex caused by viscosity poses a difficulty for F similarity. In addition to the hydromechanical difficulties of

similarity, modeling of settling matters poses a problem for model tests of

sedimentation of matters in a model sedimentation basin. In the models of

68
harbors, specific gravity is adjusted to fit F similarity. A simple solution

for model tests of sedimentation in the model. In this case, however, the

behavior of the settling matters will be distorted under either of the similarity laws, if the model of a reclamation site, for instance, is constructed

ia geometrical similarity to the prototype. Therefore, an ie-al, vertical,

an. two-dimensional sedimentation basin is considered to reaLize similarity of

sedimentation phenomena. This method is called similarity of water area load

and used widely for works related to water treatment. In this case, sedimentation is idealized to lessen hydromechanical value. However, the item of

speed will become closer to that of the prototype, slower than R similarity,

but greater than F similarity. In these tests introduced here, emphasis was

placed on conformity with the prototype regarding water area load on the basis

of the similarity law of Frouds. The scales of the model are shown in

Table 4.

Conditions of Tests

These conditions consider test cases such as A and B as well as test

equipment and method of test.

.Case-A. The outline of the findings of the survey, which were made

to develop the prototype for this case, is shown in Table 5.

TABLE 4. RELATION OF SCALE

Similarity of Water

Item Frouds Similarity Area Load

Horizontal length Lr

scale

Vertical length scale Hr Hr _ Lr2/3

Horizontal flow rate Vr Vr - HX1 /

2 Vr - Lr11 3

Flow rate Qr Qr - Lr Hr 3 /

2 Qr - Lr2

Residence time tr tr - Lr Hr-11 2 tX - Lr2/3

Soil particle dr dr - Lr-k.Hr3/ 4 d, - 1

Water area load Vor Vor - Lr-1 .Hr 1/

2 Vor - 1

On the basis of above findings, the horizontal length scale of the model was

made 1/30, and "Kasaoka clay" was adopted as sample soil as its composition

resembles that of soils around the sludge outlet of the prototype. Specifications of the prototype and the model are shown in Table 6.

b. Case-B. Conditions of reclamation are numerous, including the plane

shape of the landfill site, water depth, inflow, density of inflow

and grading of inflow. This case was considered as an extension of

CASE-A and a prototype having the same plane shape, inflow and

69
TABLE 5. RESULTS OF ON-THE-SPOT SURVEY

Position Item Result

Sludge inflow SS 70,000-200,000 mg/I

Inlet point Average 115,500 mg/I

(Sludge outlet) Sludge inflow grading Particle size accumulation

curve (Fig. 2-6)

Water depth at landfill site 0.3-3.4 m

Average 1.0 m

Landfill

site Slurry SS near sludge outlet 8,000-41,000 mg/I

Average 20,000 mg/I

Slurry grading near sludge Particle size accumulation

outlet curve (Fig. 2-9)

Rate of outflow 760 m3/h

Outlet point Surplus water outflow SS 13-181 mg/I

(Spillway) Average 50 mg/I

Surplus water outflow Particle size accumulation

grading curve (Fig. 2-9)

inflow grading as the model was presumed and such test parameters as

water depth, inflow density and devices for promotion of settling

within the reclamation site like a partition weir were selected.

The parameters are shown in Table 7.

c. Test cases, Test caip are shown in Table 8.

d. Test eguipment. The flow chart of test equipment is shown in Figure 11. The positioning of precipitation devices and their cross

section are given in Figures 12 and 13. The test water tank is

shown in Figure 14.

e. Method of test. Appropriate amounts of seawater and sample soil

were put into the raw water production tank so that raw water of

desired density could be obtained. They were mixed up using the

agitator and circulating pump. Raw water was then poured into the

dry test tank up to the level 1 or 2 cm below the surplus water

overflow line by a fully opened pump (more than 200 I/min). Then

the flow was adjusted to a set volume. For each test case, raw

water was poured for 2 or 3 hr after confirming the state of stability by the oscilloscope of the turbidimeter. Water samples were

taken at 15-min intervals and were measured and analyzed regarding

each one of the items.

70
TABLE 6. SPECIFICATIONS OF MODEL AND PROTOTYPE

Item Prototype Model Note

Horizontal length Lr - 1/30 - 0.033

scale

Vertical length Hr - 0.104

scale

Landfill site 0.3-3.4 m 3.1 - 35.4 cm

water depth Average 1.0 m Average 10.4 cm

Overflow width at 6.95 m 23 cm

spillway

Rate of inflow 760 m3 /hr 14.1 I/min

Raw water inflow 20,000 mg/1 20,000 mg/I Subject:

SS Slurry near

sludge outlet

Water area 27,600 m 30.7 m

Water area load 7.65 x 10 -- m/sec 7.65 x 10 -- m/sec

TABLE 7. TEST PARAMETERS

item Prototype (Assumption)

Landfill site (Average) 2m • 3m

water depth

Raw water 10,000 mg/I • 20,000 mg/I

inflow SS

Devices for Partition weir . submerged dike

precipitation Protector

Results of tests

Case-A

An example of sequential measuring of SS and outflow of raw water and

surplus water is shown in Figure 15. Additional findings follow.

a. Confirmation of set conditions. Conditions set for tests such as

the rate of flow, raw water density, and grading and test results

are shown in Table 9 and Figure 16.

b. Surplus water and grading, The results of tests on surplus water

density and grading are shown in Table 10 and Figure 17.

71
FA

SCd

*0 4) 4) 4

o, 0 0 2 0

41) 0) 0

i ) 0os. 01.4 0 0

"4"~4 " 4) " 4J3) 4J 4

P.-1 -41 a .41 00 0

O 4.)4 A.) "4J 4)

.4 0 4 0 $4( 0 . 1. 54 C4 Cd C

A.4 N 4 6

bo 00C

a 0 000 00

0d 0~ 0 0 0 0 0 0

4-40 0, 0 0 0 0 0 0

0 0 Cý ý C T 0

*Y* CII 04 eý:cv2 04.. 4 y

4 1-4 04- 04

0 0 4

co )4)

00

r-.4 04

"0. 0c

0 coPE-44 W u

0

"q 41 UL

04 0) 0 ) 01002 C 2

0 0000 00

"4 "72
(D Raw water Production tank

0J Teas t water tank (landfill site model)

(1 C at ch b as in

%~ Sead Imean t at Ion baa i n

(&I D ra in d it ch

0 C o agulant adding equipment

,S F Iowmeter

(D T u rb id imeat ar

Figure 11. Flow chart of test equipment

I - Pan f 

IsI u d 9 e o ut) I e

Figur 12. ositoning tof preipiainreie

S Ub rc Me d i 73
PertlItion weir S bmerasd dike Protector

;T~ H= 5cm

-I '°'aa"

Figure 13. Cross section of precipitation devices

Figure 14. Test water tank (landfill site model)

c. The SS weight by particle size. The SS weight by particle size per

unit volume of water as calculated from the test results on density

of raw water and surplus water and on grading are shown in Figures 18 and 19. The difference of surplus water SS weights in the

prototype and the model is calculated and shown in Figure 20. Test

results regarding the removal rate by sedimentation are shown in

Figure 21.

Case-B

The following figures and tables illustrate test results of Case-B.

a. Confirmation of set conditions. Test conditions set for flow rate,

raw water density and grading, and test results are shown in

Table 11 and Figures 22 and 23.

74
15 z] i - -*.0 S,,l, t r

A I-AN O lu .A t r SS

• -- - - A S..rvl,, l As AVt r v

"A.-" • .. Is . .. -- ,•-•V - -

I p _ i . . . . . . . . . . . . . . . . A s * # I A r S S I * ) . . . I

'VV

5 . -

A'.

A + -... . . . .. . . .. ..

-- "- - - -. ----

, , - 4.,• , S,...

. . i , , , . x . - 2 -

0 , , 10 1 2 13 144 5 l 7 6

I o s t t 1, r

Figure 15. Test result (example) case 1-1(2)

TABLE 9. DISCHARGE AND RAW WATER DENSITY

Case Flow Rate (I/min) Raw water density (mg/1)

Set value Survey value Set value Survey value

(av.) (av.)

Case-i 13.8 11.400

Case-i • 13.9 13,800

Case-i 14.1 13.7 20,000 13.200

Case-i •_ __ 14.0 12,900

b. Surplus water and grading. The results of tests on surplus water

density and grading are shown in Table 12 and Figure 24 and 25.

f. Rate of removal by sedimentation by particle size, Rates of removal

by sedimentation were calculated from test results on density of raw

water and surplus water and on grading (Figures 26 and 27).

75
i: __1.. I 1: F 17

10 I I

. T .. . . .. . . . . .. . . . . . .. .. k

Perticle size D (urn)

Figure 16. Particle size of raw water

TABLE 10. SURPLUS WATER DENSITY

Case Prototype _______Survey Value

(vrg) Sample-i Sample-2 Sample-3 Sample-4

.Case-i-• 190 mg/I 140 mg/I 181 mg/I 174 mg/I

Case-i 132 139 137 136

Case-i • 5 mg 221 228 204 218

Case-i _______ 167 124 193 162

Cons iderat ion

Case-A

For this case, survey results were taken as the prototype and conformity

with the prototype regarding the Frouds Law, and the water area load was considered as basic law of similarity; the size of the model was set in a scale

of 1 to 30 in horizontal length and 1 to 30 in vertical length, all to seek

reproducibility of surplus water density.

76
44(

401

1.600100

.600 1

1400 B

1200 2 ~ ~ -I ~- - 1

.0000I Patce ie 0 un

FigureA 18 wegh of- ra wae 77S pe uCD voum

8077
B * of C - D- 0 .. R -

20 - -!: --- Zi S= gig 0= i==.- -- I

15

101-94 Ship,- AN _ *-jA: = i

10

20

P articIas i za ( m 100

Figure 20. SS egtourplus water Spwihtdfereunitiaolum

betee prottyp ants

30 1 T 78
as-I0ROl o rpu WAZ e atcesz

94:

P r0 300tY P.rtisl Siz D im

Figure 1. Rat of remva bysdmetto

TAL DICHRG 11. Aa A AEEST

____ _ Se vau Suve value (wav. St vau SuSe value (av.)

Case-2 I 13. 2 0000 12,000ti Ia

Cas -3 13. _____gur 12,700

CCseC -14.0 ram0 ()o pr 11,500inS il

Cae: 13. 2000 13,200I

Case-7 1~3.61,0

Case-8~~~~C _______ 139b___ _1,0

79I U) t
60 7TT Ii

4 10 H, :H10 Partile 0CueA sze 

40 5Ii71~Ij : I Ho I:

08
TABLE 12. SURPLUS WATER DENSITY

Survey Value

Case Sample-1 Sample-2 Sample-3 Sample-4 Average

Case-2 • 248 mg/I 326 mg/1 331 mg/2 340 mg/f 312 mg/I

Case-1 214 154 150 173

Case-3 256 254 255

Case-4 193 191 239 208

Case-5 62 73 91 76

Case-6 51 57 52 54

Case-7 68 60 41 57

Case-8 91 66 67 =75

A. On auality of surplus water. Regarding the quality of surplus

water, following assertions can be made on -he basis of comparison

of test results with the prototype.

(1) Four model tests indicated an average surplus water SS density

of 173 mg/I (136 - 181 mg/I) against the prototype's average of

50 mg/f (14 - 181 mg/I), indicating a difference of about

120 mg/I.

(2) Regarding SS grading (Figure 17), particles or more than 10 pm

accounted for 20 percent of all particles in the prototype,

while the model tests showed the size group occupied only

5 percent. This difference was considered because of refloating of particles in the prototype at the surplus water outlet.

Model tests in general showed greater distribution of finer

grains than in the prototype.

(3) As to the sedimentation removal rate by particle size, the prototype showed no remarkable changes for size groups, indicating

the rate of more than 99 percent for all size groups. In the

model tests, the size group of more than 10 pm showed a rate of

nearly 100 percent, but finer size groups indicated various

trends: the 2- to 10-pm group showing a gradual decrease, the

0.8- to 2-pm group a gradual increase, and the 0.4- to 0.8-pm

group a gradual decrease. Overall, the removal rates in model

tests were lower by 2 to 5 percent than those of the prototype.

81
F V IJ.-!--•h--:- ' f ; !1

90 oC 0 ("m) pe 

I I0 100

P ". ic0e size 0 (uJ)

Figure 25. Surplus water particle size (case wfheree

preipita warer etsup) Tdevce 

68 .. .. 2 ...

Po r o t, 0 t y p III

30 -:,7! 7 •

........... 1 ! 11 1 1 ~

3o ~ ~ ~ ~ ~ .- ~ P ,"l c--tii!• I!/.,i -i ze Dl ( & III)i~llT .I~l 

Figure24. Su plu ae article size (cs of cang

Figure 25.Suplus n wandera warter desizetcsewhr

precipiatinsevie r e

82
100

I :1 _

Case3 - 3l

I N :1 1

_____ L 'I il I II.. H v

Cas -. II ~II- If I~ I I II so

P ar t iclIe s i xe D (urn)

Figure 26. Rate of removal by sedimentation by particle size

(case of change in depth and raw water density)

Cast -5'.~ ~ i~~'~IJII

Case -

zae 5 7!~.~ V T__ T~~~;i .A

II~~ HII if

0LL 1. 00

S83
k. On test conditions, Regarding the difference of surplus water density, the following assertions can be made in view of the test

conditions:

(1) Test condition of inflow was set at 14.1 I/min but the test

results were a little smaller, showing the averages of 13.7 to

14.0 I/min. Though there were changes during the passage of

time, they are not considered as commanding factors, judging

from the reaction of surplus water density in a state of

stability.

(2) Raw water density stood at an average of 12,800 mg/I (11,400-

13,800 mg/1) against the test condition of 20,000 mg/I. This

considerably lower density was caused by the sand sedimentation

in the raw water supply pipe. Raw water density can be a factor to force sedimentation of finer particles near the sludge

outlet as in hindered settling and thus can have strong

influences on the quality of surplus water. Their relationship

must be grasped more accurately.

(3) Raw water grading (Figure 16) was a little coarser than that of

the prototype but both can be said to be very close in composition. However, in view of the results concerning the raw

water SS weight (Figure 18), absolute load of the SS components

of less than 10 pm of surplus water was small by the difference

of raw water SS densities. The influence of this difference on

the removal rate, together with the relation with raw water

density, should be made clear in the future.

c. Summary. The results of model rests indicated a surplus water density higher than the prototype by about 120 mg/I because of the

outflow of finer particles of less than 6 pm with the peak of 2 pm

from the surplus water outlet. Their failure in settling was a

tendency observed in all four tests regardless of the changes in

surplus water density, showing a remarkable difference from the

prototype. Causes are complex including the problems of condensation, hindered settling, difference of characteristics between sea

clay and sample soil used in model tests, and so on, all very difficult to clarify. Collection of more data and supplementary experiments are needed for prediction of quantitative surplus water

density.

Case-B

For this case, survey results show the influence of water depth, raw

water density, and precipitation devices on surplus water density.

a. Influence of water depth of reclamation site, Surplus water density

was indicated at 173 mg/I (136-218 mg/I), at 243 mg/A (173-312 mg/1)

and at 255 mg/A, corresponding to water depth of 0.1, 0.2, and

0.3 m, respectively. So far as the averages are concerned, the

deeper the depth, the greater the density, but the differences are

not great at all. It is difficult, therefore, to assert that water

depth has a clear-cut impat on density. When water area loads are

made similar, water depth h,.. nothing to do with the density in an

84
ideal sedimentation basin, barring the possibility of refloating of

soil particles, and the test results indicated this trend. It is

considered because of the existence of marginal water depth contributing to the resident flow inside the landfill site.

b. Influence of raw water density. Regarding the five cases where the

average model water depth was 0.1 m and raw water density was

measured at 6,470 to 13,800 mg/I, it can be said that surplus water

density tended to decrease as raw water density increased. High

density raw water is said to contain less soil particles and to tend

to lower the density of surplus water. The tests proved this

tendency.

c. Effects of precipitation devices. A partition weir, submerged dike,

and protector were set up in the model with an average depth of

0.1 m and compared the effects with the case of no such devices. It

is generally said that the partition weir is effective in

streamlining the flow and in prolonging the residence time to promote settling; the submerged dike is helpful in shortening the

distance for soil particles to reach the bottom and in controlling a

flow of high density; and a protector is said to be effective in

forging the settling of soil particles. Test results showed that

the partition weir and the protector, each used alone, were effective in cutting surplus water density to 75 to 76 mg/I from 173 mg/I

in the case of no such device. When the submerged dike was used

with either one of them, the density further went down to 54 from

57 mg/I.

POSTSCRIPT

Analysis of the numerical model and model tests are considered to be

useful for prediction of surplus water density at a reclamation site. In any

case, it is necessary to compare the results with the results of on-the-spot

survey and to examine their reproducibility. This time, the differences

between the onsite conditions and model tests results have been made clear

regarding the particle size distribution in sedimentation, using the model

made on the basis of on-the-spot findings taken as the prototype. From now

on, research activities will be continued on the difference of sample soils

used for model tests and on characteristics of surplus water near the sludge

outlet and at the surplus water outlet, in order to make prediction accurate

with supplementary data. Efforts will be made further to make this study

helpful for the solution of the water pollution problem involving landfill

sites in general.

85
A SUMMARY OF RECENT CAPPING INVESTIGATIONS

WITH DREDGED SEDIMENT" IN NEW ENGLAND

Thomas J. Fredette

Regulatory Division

U.S. Army Corps of Engineers

New England Division

424 Trapelo Road

Waltham, Massachusetts 02254-9149

ABSTRACT

Capping of contaminated dredged sediments in mounds at

shallow (20-60 m) offshore disposal sites with less

contaminated sediments has been used as a management

practice in New England since the early 1970's. Evaluation of the success of this technique and extension

of its use at deepwater sites (60-100 m) have been the

focus of several studies over the last several years.

These studies have included assessment of physical

mound stability, the long-term isolation of contaminants within the mounds, and surveys to determine the

feasibility of creating sediment mo-inds at sites in

the 100-m-depth range. The passage of Hurricane

Gloria in 1985 was found to have limited erosion

effects on capped disposal mounds at the Central Long

Island Sound disposal site at 15-20 m-depth. This

observation has also been supported by observations of

mound stability at several sites for up to 15 years.

Chemical profiles measured in cores taken in mounds in

1990, more than 10 years after contaminated and cap

sediment placement, had undetectable contaminant

migration. More recently, studies of mound formation

with disposed sediments at the Massachusetts Bay disposal site, in 90-m depth, have begun to support the

feasibility of capping sediments at this site and

other similar depth sites.

INTRODUCTION

The management of contaminated dredged sediments in New England has

relied heavily on the use of capping at offshore marine disposal sites. This

dependence has been based on the lack of available upland sites due to protection of wetlands, intensive nearshore development, and the much greater economic costs required for upland disposal. Capping has been facilitated by the

fact that the majority of dredging in New England is performed by clamshell

dredges which keep sediments consolidated for subsequent disposal from bottom

opening barges.

The first capping projects in New England were conducted in the early

and mid 1970's. These projects (e.g., at Brenton Reef off Rhode Island) did

not include monitoring to determine their level of success, rather it was

86
assumed that sequentially dredging to place the more contaminated sediments

first and less contaminated sediments second would result in burial. Concerns

about whether this approach actually accomplished the objective led in 1979 to

the first carefully planned and monitored capping projects. Since that time,

more than 10 capped disposal mounds have been created at New England sites and

monitored using a variety of techniques to assess their short and longer term

success (Figure 1) (Morton 1980; Brandes, Silva, and Fredette 1991; Sumeri et

al. 1991; Fredette et al. 1992). These studies include several recent investigations which have examined physical stability, chemical isolation of contaminants within the mounds, and creation of mounds at sites up to 90 m in

depth. Major findings of these recent studies are presented and discusses in

the following sections. These monitoring surveys have been conducted as part

of the U.S. Army Corps of Engineers, New England Division's Disposal Area

Monitoring System (DAMOS).

CAPPING INVESTIGATIONS

Mound Creation and Physical Stability

Documentation of mound creation and determination of cap thickness has

relied primarily on precision bathymetric and sediment profile camera surveys.

Bathymetric surveys are usually conducted before and after contaminated material placement and following the placement of the cap. These surveys are then

used to determine the lateral extent and thickness of the contaminated and cap

layers as shown in Figure 2 (Morton 1980).

Use of a sediment profile camera (Figure 3) has been a more recent addition to the monitoring protocols for capping projects. The camera provides an

excellent complement to bathymetry because it is capable of detecting the

thinner deposits (0-20 cm) that exist around the central portion of the mound

(Figure 4). Thus, managers can be provided with a much clearer indication of

where sediments have been placed during either the contaminated or cap placement phases. Following contaminated material placement, this camera provides

an ability to accurately plan coordinates where cap material is to be placed.

Once a capped disposal mound has been created, one of the primary concerns is the catastrophic failure by erosion of the cap during high bottom

current conditions caused by storms. Again, a principal tool for assessing

cap stability is the comparison of post-storm bathymetric surveys with those

conducted following cap placement. However, caution needs to be used in

interpreting differences to ensure that changes in mound height caused by

consolidation are not misattributed to erosive losses. This interpretive

difficulty was observed following Hurricane Gloria in 1985 which passed over

New England (Figure 5) shortly after the completion of two capped disposal

mounds at the Central Long Island Sound disposal site (Fredette et al. 1988).

Bathymetric surveys at five mounds, which were conducted following Hurricane Gloria, helped to strengthen support for the conclusion that caps were

effective in protecting the contaminated sediments from erosion. Four of the

five mounds surveyed showed only small changes in elevation, although one

mound that had been completed just a few months before the storm showed a

volume loss of up to 15,390 m3 . However, interpretation of the complementary

sediment profile camera surveys did not support the erosion hypothesis. Sediment profile photographs from the crest and flanks of the mound showed evidence of near-surface features (wormtubes and oxidized sediment) that were

87
UI

US Army Corps of Engineers

New England Division

Active Open Water

Dredged Material

Disposal Sites

MAINE

VERMONT -ROCKLAND

0-PORTLAND*

HAMPSHIRE

MASSACHUSETTS S-MASS BAY

N

CONNECTICU RI BUZZARDS BAY

--- NEW LONDON

CORNFIELD SHOALS

.ENTRAL LONG ISLAND SOUND *

WESTERN LONG ISLAND SOUND

Figure 1. New England disposal sites at which capping

has been conducted (indicated with asterisks)

88
15 -LANE 14

16 - I 20JANUARY &

17 19 MARCH 1979

E 18 - 2 24 APRIL 1979

X 19 - 3 20 JUNE 1979

a 20

U 21 -

22

23I I I I I I I I I

0 100 200 300 400 500 600

DISTANCE ALONG GRID LINE (m)

Figure 2. Three depth transects along one survey grid line at a

dredged-material mound before, during, and after

disposal operations. Vertical exaggeration is 25 times

the horizontal scale. The contaminated sediment was

deposited between surveys 1 and 2, and the silt cap

was added between surveys 2 and 3

still evident in photographs taken only a few days after the storm. The only

reasonable explanation was that the change in elevation was primarily

attributable to consolidation of the mound. Thus, the apparent lack of

effects following such storms and the observed stability of mounds for more

that 15 years supports the conclusion that these sites will perform as

expected.

Chemical Isolation

An often-cited concern with caps is whether they provide a long-term

barrier to release of contaminants to the environment. This concern centers

around the possibility that contaminated pore waters are released during consolidation, or in later years through either sediment pumping or diffusion.

If this possibility were true, then caps would, at best, serve only to slow

the eventual release of contaminants to the environment.

As part of the ongoing monitoring of cap sites in New England this question has been partially addressed by taking cores on three disposal mounds at

the Central Long Island Sound disposal site (Sumeri et al. 1991, Fredette et

al. 1992). The mounds selected were sampled in 1990 and represented three of

the oldest mounds: two having been created in 1979 and one in 1983. Five

cores taken on each mound were sectioned in 20-cm increments for sediment

chemistry and grain size analyses. These results revealed very abrupt

increases in both organic and inorganic sediment chemistry at depths of 40 cm

or greater (Figure 6).

CaRping at Water Depths of 90 m

While capping in water depths up to a 60-m depth has gained general

acceptance in New England, extending the use of this technique to sites in

89
END W4

(HOUSING FOR RVNM FRAME

__MUD DOOR

Front View

Figure 3. Schematic diagram of the REMOTSO sediment

profile camera

90-100-m depth remains very controversial. This controversy has been maintained because of a near absence of monitoring data on sites greater than a

20-m depth, earlier studies of disposal at New England's 90-m site (Massachusetts Bay Disposal Site) that failed to detect mound formation, and, in the

New England situation, the proximity of the proposed site to areas heavily

used by endangered and protected species of whales. Later analysis of the

study that failed to detect a mound concluded that lack of point disposal and

limitations of the detection limits of the surveys and equipment were likely

to be the principal reasons for lack of mound detection and not dispersion of

the material following disposal (Bajek et al. 1987).

Consequently, monitoring surveys at New England's deepest offshore disposal site in Massachusetts Bay have focused on answering the basic question

about mound formation. This answer has been reached by disposing of all sediments since 1985 (7.2 million cubic meters) at a taut-wire moored buoy stationed within the site. Sequential bathymetric and sediment profile camera

surveys have been used to document the lateral and vertical distribution of

sediments through the most recent survey in 1991 (Science Applications International Corporation 1990; In press).

In contrast to predictions based on the earlier study, the surveys have

documented the development of a mound 1.5 meters in height having a radius of

approximately 400 meters (Figure 7). Given the relatively low bottom currents

at this site (10-20 cm/sec) and the protection from wave effects that this

depth provides, this deposit is expected to remain stable.

90
7 N. 7b 44

7~~9 -0'34 

?A 0

4)

00

0 0)

4~) 10

010

II0 0)-

I;-)c 0 0 0 .40)

/4 C

Do5 $4 (D U

c bo).w0

41 0 4)

N.4

SOO

z -WW4-4

91
E

00 FAg

Cu c

,-1-4 0 0

0 '

00

3:* 1

0 40 co-0

41 )-

aft r-4Q-0

0 4) u~

00

0 "4

0 ~bOQ

442C
0-20- COPPER

ZINC

20-40-

40-60 -

w

q 60-80 - 0

0

z

0 ~-80-100 CL

w

a100-120--

120-140

140-160 •_[_

0 100 200 300 400 500 600 700 800 900 1000

PARTS PER MILLION (PPM)

a. Copper and zinc concentrations

Figure 6. Core sections of copper and zinc and four PAH

concentrations on a capped mound 11 years after

placement; cap/contaminated interface observed

in the 80- to 100-cm section (Continued)

93
0-20- PHENANTHRENE

- ANTHRACENE

20-40 - FLUORANTHENE

- PYRENE

O 40-60

w

0

10 0-1200

140-160-0

0 10 20 30 40 50 60 70 80 90 100

PARTS PER MILLION (PPM)

b. PAH concentrations

Figure 6. (Concluded)

94
DISCUSSION

Monitoring of capped disposal mounds and sediment behavior at sites of

various depths has increased the confirmation of both the ability to cap contaminated sediments using conventional dredging equipment and predictions

about cap performance in isolating contaminants from the environment. However, despite the large body of evidence supporting the success of capping,

there remains a great deal of skepticism within the environmental community.

Thus, there is still a need for continued monitoring and research to improve

the information base on which to evaluate the capping alternative relative to

other sediment management options.

The principal research need for the deeper water sites is a demonstration project to confirm the theoretical predictions about sediment behavior.

Existing mathematical models (Brandsma and Divoky 1976, Johnson and Holliday

1978) and the empirical results from DAMOS monitoring surveys both support the

prediction that contaminated sediments could be placed on the bottom in deposits similar in overall extent to those which have been capped in shallower

sites. Confidence in the ability to then place cap sediments over the contaminated sediments and their long-term isolation of these contaminants should be

directly transferable from our shallower water experience. Nonetheless, until

a demonstration of these assumptions are made the most ardent of critics will

remain unconvinced.

It is my belief that as we continue to study the long-term effectiveness

of capping at offshore sites, we will find that this alternative, while not

providing for 100 percent sequestration of contaminants, provides the most

practical solution for the majority of contaminated sediments. Other remediation alternatives, such as diked containment areas, borrow pits, or treatment,

will seldom be worth the incremental costs that such solutions demand when

carefully evaluated relative to the incremental benefits.

95
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ci96
REFERENCES

Bajek, J. R., Morton, R. W., Germano, J. D., and Fredette, T. J. (1987).

"Dredged Material Behavior at a Deep Water, Open Ocean Disposal Site," Proceedings, 20th Annual Dredging Seminar, Western Dredging Association, September 1987, Toronto, Canada, pp 95-107.

Brandes, H., Silva, A., and Fredette, T. (1991). "Settlement of Offshore

Mounds of Capped Dredged Materials," Maritimes, Vol 35, No. 3, pp 12-14.

Brandsma, M. G., and Divoky, D. J. (1976). "Development of Models for Prediction of Short-Term Fate of Dredged Material Discharged in the Estuarine

Environment," Contract Report D-86-5, U.S. Army Engineer Waterways Experiment

Station, Vicksburg, MS.

Fredette, T. J., Morton, R. W., Bohlen, W. F., and Rhoads, D. C. (1988).

"Erosion and Resuspension Effects of Hurricane Gloria at Long Island Sound

Dredged Material Disposal Sites," paper presented at U.S. Army Corps of Engineers' Seventh Annual Water Quality Seminar, February 1988, Cnarleston, SC.

Fredette, T. J., Germano, J. D., Kullberg, P. G., Carey, D. A., and Murray, P.

(1992). "Chemical Stability of Capped Dredged Material Disposal Mounds in

Long Island Sound, USA," Chemistry and Ecology, Vol 7, pp 173-194.

Johnson, B. H., and Holliday, B. W. (1978). "Evaluation and Calibration of

the Tetra Tech Dredged Material Disposal Models Based on Field Data," Technical Report D-78-47, U.S. Army Engineer Waterways Experiment Station,

Vicksburg, MS.

Morton, R. W. (1980). "The Management and Monitoring of Dredge Spoil Disposal and Capping Procedures in Central Long Island Sound," Second International

Ocean Dumping Symposium, Woods Hole, MA, DAMOS Contribution No. 8, U.S. Army

Engineer Division, New England, Waltham, MA.

Science Applications International Corporation. (1990). "Monitoring Cruise

at the Massachusetts Bay Disposal Site, November 1988-January 1989," DAMOS

Contribution No. 73, U.S. Army Engineer Division, New England, Waltham, MA.

Science Applications International Corporation. "Monitoring Cruise at the

Massachusetts Bay Disposal Site, August 1990," DAMOS Contribution (in press),

U.S. Army Engineer Division, New England, Waltham, MA.

Sumeri, A., Fredette, T. J., Kullberg, P. G., Germano, J. D., and Pechko, P.

(1991). "Sediment Chemistry Profiles in Capped Dredged Material Disposal

Deposits: Results from Three U.S. Army Corps of Engineers Offices," Proceedings, 24th Annual Dredging Seminar, Las Vegas, NV, pp 161-187.

97
THE DEVELOPMENT OF CLEAN AND DENSE DREDGING SYSTEM

Akira Teramoto, Shozo Ikeda

Japan Sediments Management Association

15 Sankyo Bldg., 2-7-12, Tsukiji, Chuo-ku, Tokyo, 140 Japan

ABSTRACT

A new clean and dense dredging method was developed that can dredge the bottom sediments found in

rivers, lakes, and harbors without mixing with water.

By using this method, only a small amount of water is

dredged together with the bottom sediments, and the

quality of environment is not deteriorated.

In the course of development, fundamental tests

using a model were carried out in the laboratory basin

to ascertain the effectiveness of this new dredging

principle. The following points were confirmed at

filed tests by using a small testing machine:

p. High density dredging/transportation with the

solid concentration of over 80 percent obtainable.

b. The amount of turbidity caused by dredging operation is far less--1/5-1/10 of that caused by conventional methods (grab, cutter suction, etc.).

c. A flat finish is obtainable, with the accuracy of

flatness between -1 to +5 cm where the dredged

soil thickness is 30 cm.

This report summarizes the outlire of the system

and the development process form the fundamental model

tests to the positive filed tests using the small

testing machine and then to the execution of real

dredging work.

INTRODUCTION

The waterfront development has progressed throughout Japan, and the

creation of spaces where people feel closer to water, beneficial to both man

and nature, are in urgent demand. Especially the improvement of water environment, to make it amenable to human beings, has gained in importance.

Usually the quality of water cannot be improved without improving the

bottom quality, and one of the solutions is to remove the bottom sediments,

thus the dredging is carried out. The conventional dredging methods generally

use grab or cutter suction dredges. The cutter suction pump-type dredging is

disadvantageous because it requires a large sedimentary area for the great

volume of water sucked in with the bottom sediments, and such water is

98
detrimental to the transportation efficiency. In the case of the grab-type

dredger, the turbidity caused by the dredging operation and inability to

dispose of the large volume are major drawbacks. Therefore, an improved

dredging system was in keen demand.

This newly developed clean and dense dredging system should meet the

demand. Rotating and advancing, the developed dredging equipment is partially

inserted to the bottom sediments quietly, at a rotating speed simultaneous to

its advancing speed to cut off and lift up the bottom sediments. This system

can dredge bottom sediments just as the sediments accumulated, without disturbing the sediments. This system can dredge bottom sediments, not allowing

extra water to enter, not causing environmental turbidity.

OUTLINE OF THE SYSTEM

Principle of Dredging

The basic principle of dredging is to rotate the dredging equipment

having a plurality of bucket chamber formed by sequentially projected sliding

blades, synchronously to its advancing speed, and to penetrate the bucket

chambers into the bottom sediments to cut and lift up the bottom sediments

gently.

Structure of Dredging Equipment

Broadly, the dredging equipment is made of three major components. It

is structured as shown in Figure 1. The dredging drum (item 1, Figure 1)

comprises two side

VT \\MP

i (~ ljl,,I ,s~i, W-le. • ) I Iii insel

Figure 1. Structure of dredging equipment

99
plates and an inside cylinder, which is rotated by an oil hydraulic motor.

The inside cylinder has 12 radial slits for the sliding blades (item 2) to

slide in and out. The casing cover (item 3) has a bottom scraper in its

lower section, a screw conveyor and a housing cover on the top, and guides for

sliding blades in the intermediate section. The casing cover is fixed to the

frame. Twelve sliding blades installed in the dredging drum are paired with

each two facing each other connected by connecting rods and move in unison.

As the dredging drum rotates, those sliding blades on the upper side are

pushed by the guides and the upper housing cover to be retracted into the

drum, while the blades at opposite side are forces out of the drum to form a

rectangular bucket chamber between two side plates of the drum.

Principle of Motion

Figure 2 shows the motion of dredging equipment.

(D) Dredging equipment moves forward and rotates

Upper cover

Rotate ' 7

Advane ~ ' -Guide for

Advance ~ sliding W"k

Bottom scraper

(1) After roating 60"

Af Aer moating 120"

*(D After rotating 150"

S®0 After routing 210'

Figure 2. Details of dredging motion

100
A. When the dredging drum rotates and moved forward, the buckets at the

lower part of the drum are consecutively penetrate into the bottom

sediments. By synchronizing the speed of rotation and advance, the

relative speed difference between the bucket and the ground is

brought to zero, and the bottom sediments are enclosed inside the

buckets without disturbance of the ground.

b. As the bottom scraper advances, the bottom sediments in the buckets

are cut and lifted up.

Q. The dredging drum rotates and the bucket holding bottom sediments

ascents along the bottom scraper and further above to the screw

conveyor chamber, then the sliding blades gradually slide intc

drum and the bucket disappears.

As is clear form this principle of motion, the theory that made clean

and dense dredging possible comprises the following three functions, and their

details are as follows:

D. Discharging water while the sliding blades Denetrate into the bottom

sediments, As shown in the principle drawing Figure 3, when the

bucket having several holes in its bottom is pressed into the bottom

sediments, the water inside the bucket is forces out through these

holes and replaced with the bottom sediments. The process is continuous due to the rotation of the dredging drum and made possible

the intaking of bottom sediments into the bucket without adding

extra water.

b. Discharging water while the bottom sediments are being lifted.

Figure 4 shows how water is discharged while the bottom sediments

are being lifted. When water is lifted together with the bottom

sediments as shown in bucket chambers A and B, its fluidness and the

pressure from the bottom sediments which are filled in the upper

screw-conveyor chamber allow water to flow down through the drainage

holes provided in each sliding blade and so the water is prevented

from going up into the screw chamber.

Surface

Bucket

Hole Wcneo

.,p.g chamber

Forced into Bottom scraper ..- , ..

bottom sediments/

we Al Bucket chamber A

Bottom -'Die • "

.... Bucket chamber B

Co0eio bucket bottom •.

Figure 3. Discharge water function Figure 4. Discharging of water

while penetrating while bottom sediments

are lifted

101
g. Preventing extra water to enter. The purpose of providing a cover

above the screw-conveyor chamber and retracting the sliding blades

into the inside cylinder of the dredging drum is to prevent the

entry of extra water from the above, as well as to give the sliding

blades at the bottom part a reaction force to penetrate into the

bottom sediments, and also special rubber sealings to effectively

prevent the entry of water.

Lifting and Transfer of Dredged Bottom Sediments

Bottom sediments filled in the screw-conveyor chamber are carried to the

end part of the chamber and then discharged. The discharge pipe is connected

to the suction pipeline of a positive-displacement type pump of which the flow

rate may be controllable, and the bottom sediments discharged from the screwconveyor chamber are sucked by the pump keeping the natural water content of

bottom sediments as they were at the bottom and transferred out of the

dredger.

The screw-conveyor's plug effect prevents entering of water by means of

the suction force of the pump. Image drawing Figure 5 shown the flow of

dredged bottom sediments from collection through lifting up to transfer.

Discharge

0.

Transfer pump "0 - Scto Suction

Pontoon /

Dredging equipment Screw conveyor

Sliding blade

Direction of dredgingc

Bottom sediments Bottom scraper

Direction

of rotation

Figure 5. Flow of dredged bottom sediments

Comiosition of System

As shown in Figures 6 and 7, this dredging system in composed of the

dredging equipment, a transfer pump and its suction/discharge pipelines, a

maneuvering winch, an obstacle remover, and an automatic tracking laser positioning system for the display and monitoring of the dredging position.

Dredged bottom sediments are transferred by a high-pressure transfer pump to

102
Figure 6.loatnceptualidaigonsseeo ak/ies

Obstaclesace emve

Figure 7. Conceptual drawing of wv-eitn system for harboivr use

1034
its destination via a floating pipeline. In the case of long-distance transfer, a booster pump should be used as needed.

The obstacle remover collects small obstacles in the bottom sediments

before dredging. The combination of a fixed rake biting into the bottom sediments and an elevator rake meshed with it and rotating effectively removes

obstacles.

This dredging system can be set up for both lake/river use and harbor

use. The suitable setup may be chosen. Figure 6 is a conceptual drawing of

the system for use in a lake, marsh, or river (pontoon traveling type). It

has a divisible and portable structure, and overland transportation is possible. Figure 7 shows the wave-resistant system for harbor use (platform car

shifting type). They are operated as follows:

A. For lake river use. The dredger pontoons are maneuvered by means of

ropes hung between two spud pontoons located far apart (about 50 to

60 m), without laying anchoring wires.

k. For harbor use. A platform car on which the dredging equipment is

mounted moves back and forth in the opening at the center hull of

the dredger. The operation is carried out by means of two maneuvering wires and tow spuds.

Distinctive Features of System

The features are listed below.

A. High density dredging (the solid concentration of 80-100 percent)

with no addition of water and long-distance transportation of slurry

maintaining high density are possible.

k. Bottom sediments with a wide range of properties (natural water

content between 80-400 percent) can be dredged.

c. Dredging is operated without disturbing the bottom sediments, so the

environmental turbidity is very little.

d. The bottom scarper ensures flat and reliable finish of dredging.

HISTORY OF DEVELOPMENT

Because of its unprecedented dredging principle and mechanism, the

development of this system began with theoretical analyses of the dredging

principle and the transfer system of dredged slurry. Next, fundamental tests

using a model were carried out to confirm the feasibility of the system. Then

the actual development proceeded through the designing and producing of a

small testing machine to a field performance tests and finally tests at

various dredging sites.

104
Analysis of Dredging Principle

Dredging Theory

In general, the excavation theory of a cutter used by cutter suction

dredges are expressed by a trochoid curve (Figure 8). Its principle is that

the cutter, usually composed of five or six blades, rotates at a speed of

10-20 rpm, then moves crossways mincingly along the curve in Figure 8 cutting

the soil in thin slices, raking up and mixing with water to suck up by a pump.

As against this, a theoretical curve of the sliding blades of the newly

developed dredging system in shown in Figure 9. To synchronize the advancing

speed with the speed of rotation, the situation is similar to that of an automobile tire. The locus of a point on a revolving circumference shows rectilinear motion near at the lowermost point as in Figure 9. The principle is

making use of this X of the cycloid curve, and the sliding blades penetrate

into the bottom sediments almost unresisted, not disturbing the bottom or

moving in at after the penetration, thus causing no turbidity.

y D

R1

0 E

Figure 8. Trochoid curve Figure 9. Cycloid curve

Correlation with Soil Strength

For quantification of the above theory, the sliding blade has to have

correlation in strength with the bottom sediments into which it penetrates.

At the same time, the force required for penetration to lifting up of dredged

bottom sediments in the cover (rotating torque of the dredging equipment) must

be calculated. Formulae (l)-(4) are for the calculation of these forces. The

required torque for the dredging equipment can be obtained by multiplying

radius length of rotation to these forces.

Penetrating force of sliding blade

R - 8 CP.AP+. Ca.As (1)

Component force R4 - R.sin i

105
Adhesive force of bottom sediments to the side plates

a3 4 *rr2 [T w fsin - ] (2)

Force of blade pressing bottom sediments

P- B{(-t - v.)H+ 2+H} (3)

Force to lift up dredged bottom sediments

F -4 q(-t - -y.)(1 + p) (4)

where

CP - adhesive force at blade tip

Ca - average adhesive force per full penetrated blade length

AP - area of blade tip

As - area of blade side

9 - blade penetrating angle

r - blade tip rotating axis

B - blade width

it - weight per unit volume of bottom sediments

- weight per unit volume of water

H - thickness of bottom sediments

- shearing strength of bottom sediments

q - capacity of bucket chamber

p - friction coefficient of bottom sediments and blade

Formulae (5 and (6) are for the calculation of strengths of the blade

member against the above external forces. Table 1 is the results of trial

calculation for three types of bottom strength.

Bending stress caused by normal load

a = B2 (5)

Bending stress caused by concentrated load

OM M a- O H (6)

106
TABLE 1. CORRELATION BETWEEN GROUND AND BLADE STRENGTHS

Item Notation Unit Case I Case 2

Natural water content W % 100 300

Weight per unit volume -t t/m3 1.45 1.17

Shearing strength T t/m3 1.20 0.30

Penetrating force of a blade R t 0.32 0.08

Adhesive force of bottom sediments S t 1.10 0.28

to the side plates

Force of blade pressing bottom Pp t 0.89 0.20

sediments

Force to lift up dredged bottom F t 0.31 0.12

sediments (4 chambers total)

Effective driving torque Tr t - m 2.54 0.69

Load/blade (1 peace) fu t - m 1.01 0.27

Bending stress (normal) a tim' 0.50 0.12

Bending stress (maximum) a max. t/m2 1.33 0.33

where

S - stress modulus

p - uniformly distributed load

P - concentrated load

z - section modulus of blade member

Principle of Slurry Transfer

For the transportation of dredged bottom sediments lifted, as it is not

added with extra water, a special transfer pump system is needed. Here it

uses a squeeze pump which is a kind of concrete pump. The theoretical formula

for the pipeline-transfer of slurry that used this pump follow. Table 2 gives

examples of trial calculations.

<Theoretical formulae taking slurry viscosity into consideration>

Slurry resistance in pipeline-transfer

=fa'-yLv 2 (7)

Plastic viscosity of slurry

107
TABLE 2. TRIAL CALCULATIONS FOR PIPELINE TRANSFER

Item Notation Unit Case 1 Case 2

Natural water content W % 150 300

Weight per unit volume ft t/m 3 1.37 1.22

Solid concentration by apparent a 100 100

volume percent

Solid concentration by true volume Cv 20.6 11.4

percent

Plastic viscosity pn Pa-s 0.021 0.006

Yield rate tv N/M2 15.1 2.30

Specific plug radius a -- 0.78 0.71

f (a) .... 0.201 0.276

Reynolds number -- 249 1840

Coefficient of resistance f-- 0.050 0.032

Pipeline length L m 500 500

Pipeline diameter D m 0.15 0.15

Slurry resistance in pipeline- Hf m 136 22.3

transfer

Pump head Hr m 150 33.0

fB - 1.14"10"3

.exp(14.2"C,) (8)

Yield value of slurry

ry = 2.33oi0°q."19 (9)

Specific plug radius

Dory(a 4 - 4a + 3) (10) 24.voa

Reynolds number

ReB ' ymv*D . a - 4a + 3 f(a) (11)

gVB 3

108
f(a)

9 5 +6a- lla 2

f(a) -* (3 + 2a + a2 )2 (12)

From Formulae (8), (9), and (10), "a" if obtained, and from (11) and

(12), "RP" is obtained. Read the value of "fi" from Figure 10, then substitute in (7) to obtain "Hf".

where

Hf - Slurry resistance in pipeline-transfer

f- Coefficient of resistance

B- Plastic viscosity

C, - Solid concentration by true volume percent

v - Current velocity

ry Yield value of slurry

y - Yield value

D - Inner diameter of pipeline

a - Specific plug radius

RB- Reynolds number

7- Specific gravity of liquid in pipeline

g - Acceleration of gravity

f(a) - Function of "a"

L - Pipeline length

- ~Slurry- ;;M .,

4aFigure411 10. Cofiintoteistnce

Tests ~ Moe ~ i ~ abrtoyBai ~ Usn ~ a 

1099-11121 1

2-5 4011111 IN 7

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The dredging equipment model was set on a frame of a platform car which can

109
run back and forth and crossways over the basin. Inside the basin a simulated

bottom sediment (bentonite/fly ash) ground was made (Figure 11). The model

shown in Figure 12 was made of acrylic resin so that it could be observed from

outside. Figure 13 shows the test setup.

Figure 11. Laboratory basin Figure 12. One-third scale model

Platformca

.Oil hydrulc cylinder

Scr-w conveyor driving motor • Ca~r motor

motor 

Tube pump

Discharge opening 1'" •t . Model dredger

Water tank Densimeter Simulated ground

Flow meter

Figure 13. Test setup

Contents of Tests

The specifications of the model are given in Table 3. The model was

one-third the size of a small testing machine. Tests were conducted by varying the thickness of bottom sediments to be dredged, dredging advance pitch

(overlap), dredging speed, pump flow rate, and soil properties (natural water

content).

In addition to performance data including the solid concentration,

dredging volume, configuration of dredges area, and amount of turbidity

caused, such test data as loads applied to the dredging equipment and to the

screw conveyor were self-recorded and their performances were analyzed by a

computer. At the same time, its structure and strength were investigated.

110
TABLE 3. PARTICULARS OF TESTS

Particles Model Tests Field Tests

Dredging width (W) 0.5 1.2

Soil thickness (W) 0.1 .03

Dredging speed (m/min) 1.5 3.0

Dredging volume (m3/h) 4.5 65

Transfer pipe diameter (mm) 50 200

Dredging drum diameter (i) 0.65 2.1

Dredging equipment width (m) 0.5 1.2

No. of sliding blades 12 12

Ground Simulated bottom Accumulated bottom

sediments ground sediments ground

Test Results

a. High-density dredging Rerformance. Figures 14 and 15 are the graphs

of solid concentration. The solid concentration in basic conditions

(basic particulars) was as high as above 85 percent when the ratio

of handled soil volume (by the dredging equipment) to pump flow

volume was less than 1:1. The solid concentration can be adjusted

by changing pump flow rate. In conditions with a thin soil layer or

a less dredging width, the high solid concentration can be maintained by adjusting the piump flow rate. Figures 16 and 17 show

high-density slurry being discharged during the model test.

b. Turbidity preventive function. Figure 18 shows the net contents of

turbidity generation. Even in high-density dredging the turbidity

is low, i.e., below 1 x 10-3 ton/m3 . Depending on the operating

conditions it may be even lower.

c. Accuracy of flat finish dredging, As is evident from Figure 19

showing the configuration of dredged section recorded during overlap

dredging, a very flat finish was achieved.

Performance Tests on Small Testing Machine

Production of the Small Testing Machine

Based on the result obtained from the tests using one-third scale model, a

small testing machine on a practical scale was produced. Prior to the actual

designing, the machine was designed with scrupulous care on a trial basis and

its practicality in field use was discussed. The result of the discussion was

incorporated in the designing of the components. Figure 20 is an external

view of the small testing machine.

111
x: Buie oedms 0 Owtmep comditiom SOB Oth•wa 0.11nm OI,

100 - SIiic .m s 0 100 Sa M 0.11a I magugw oi *. * bud+u. w+S."04 . . I7 ..... l dj msI m d I.5 iIV 'iu ..+..... .• .... . . .+ -+ I D5..... .d gs q q u d .5-S 1m

• i i • . * o: mmi by,. amaemdi

I Dr n 0 a SD dgi g 0.&A 5

88Drafting ome" 1.5 n..1m.

0 j8 ~ 3 0.9 1 1.2 0 1.3 1.1 

Pump flow volume Pump flow volume

Handled soil volume Hanle soil volume

Figure 14. Solid concentration Figure 15. Solid concentration

(basic condition) (overlap/thin soil _j 0 layer conditions)

Figure 16. Discharging of dredged Figure 17. Discharging of dredged

soil (not using soil (using transfer

transfer pump pump)

112
a ~~SA thidoem 0.1 t "% 1 mutt . .d U'"-' 0 3 ... .. ..... .... ...... ...... -. D dq wi t ''obEI

-I ~ ~ OO-te.die wd W-- Ij 

Sohhgngwithl~~ 0.A1 a 

-- H L

D,, ,,md -• t,,,,,-- I

.-- OOverlap 0 . i h. 10cM

5 " 90 9 -100 mi .5 0z Dredging equipment width 50cm

Solid concentration % Ond ing Mud I• 5 "m

Figure 18. Net contents of tur- Figure 19. Accuracy of flat

bidity generation finish dredging

•3.000

1.1-303.000 1.870

S1130

., __• _•,•o M .•, ., ' ,,

1.707 J

Figure 20. External view of the small testing machine

113
Setup of Tests

Figure 21 is an arrangement plan for the test of the small testing

machine. Figures 22 and 23 show exterior views of the test setup.

-44a TZ

o l.Dunuimm . LX B XD 2031maX 10.14m XI.22mt~.2~g.q~mnit .m~pti -

4, Mw-v.erw - di ____3.Ot X 0 -I~mma

Maneuveing wi Oil ýhyd~raulic unit

Obstacle Squeez type Dredgingwf equisen

~~~~ Dredging equipmentlitnwnh

Figurer 21Drragnge iment oftesaliftestingmchin

sbtce eoertupmahin

L latns wich -enter114l
Outline of Performance Tests

Performance tests were conducted using the test setup intended to attain

a target dredging capacity of 30-50 m3 /h. Bottom sediments in a river in an

urban area was chosen for the tests. The test site had a depth of 5-6 m.

Performance test dredging in a soil thickness of 0.5 m was carried out in the

bottom sediments with natural water content ranging from 150 to 400 percent.

the items checked by the tests are listed in Table 4.

TABLE 4. CHECKED ITEMS

Dredging Characteristics Major Items Checked

1) Dredging performance * Dredging volume per operating hour

* Solid concentration

• Accuracy of flat finish dredging

* Occurrence and other turbidity

related matters

2) Load performance * Each machine capacities required for

dredging and the capacity balances

between machines

3) Maneuvering performance e Straightness while dredging

* Hull shift workability

4) Ability to deal with obstacles 9 Work efficiency

* Strength of machines concerned

5) Others

Target values

i) Solid concentration above 80%

ii) Dredging capacity max. 80 m3/h (per dredging hour)

The following were confirmed as fundamental requirements, and the effectiveness of this dredging system in the field was proved by the test.

A. It was proved that a high-density dredging (solid concentration

exceeding 80 percent) equal to that in the tests on one-third scale

model was possible in the field tests. Figure 24 compares examples

of solid concentrations with those obtained in the tests on onethird scale model.

b. The amount of environmental turbidity caused was very small; less

than 1/5-1/10 was caused by conventional systems (grab, cutersuction, etc.). An example of the time series graphs of turbidity

measured is shown in Figure 25.

_q. The accuracy of flat finish was from -1 to +5 cm where dredged soil

thickness was 30 cm.

•. The obstacle remover (Figure 26) caught obstacles without fail, and

its usefulness was proved.

115
S

....................................

A + ................... t To I. ,s,. mm ky. 6at.

I.... .... I,'. ax Sp,..o..... fbI raft................ • Go, u 0%n• 

.Center lower

-*. <. •Right lower" ...... . ,.""'. .. .. . . . . . . .

-- ~~~~~-li se•l~ oil ii sil

i 1 lot (sic)

Pump flew voia.u/ Hadl ed voi h

Figure 24. Comparison of solid Figure 25. Time series graph of

concentration turbidity

A. The load performances of the machines were properly balanced with

their capacities and showed that they would be able to fully cope

with changes in operating conditions.

Positive Field Tests

After improving part of the

setup based on the performance test

results, positive field tests using

the small testing machine were

carried out to confirm the practicability of the system when used in

actual dredging sites. The setup of

the tests was basically the same as

that for the performance tests.

Outline of Test Dredging Work

The phases of the work are as Figure 26. The obstacle remover

follows:

a. Test site: A water area

in the Yonago Bay Nakaumi,

Tottori Prefecture.

I. Test period: February/

Harch 1991.

q. Working conditions:

(1) Type of soil:

clayey.

(2) Dredging depth:

approx. 4.5 m.

116
(3) Dredging volume: approx. 1,000 an.

(4) Discharge length: 100 m.

Test Results

The test results were just as confirmed by the performance tests as far

as dredging performance and machine performance were concerned. By means of

continuous operation for many hours and execution in a wide area, the materials on the durability of the machines and practical operation technique for

real work were obtained. Table 5 gives examples of data in varied test conditions. Time series graphs of solid concentrations and amounts of environmental turbidity caused are shown in Figures 27 and 28, respectively. Figures 29

and 30 show the exterior view and the sampling of dredged soil.

TABLE 5. TEST DATA COMPARISON

Apparent specific Dredging

Case Test conditions Solid gravity volume per Turbidity

(Mean vatues of results) concentration Dredged soit dredging hour (ppm)

(X) per natural ground (n?/h)

No. I Dredging speed 3.6 /mmin 85 1.15 (max. 1.17) approx. 79 approx.

Solt thickness 0.3 m (max. 100) per 1.17 1-3

Pum flow rate 93 u?/h _max. 19

No. 2 Dredging speed 5.4 n/min 85 1.15 (max. 1.17) approx. 66 approx.

SoiL thickness 0.3 i (max. 99) per 1.17 1-3

Pup flow rate 77 rn/h _ax. 11

No. 3 Dredging speed 5.9 /mmin 85 1.15 (max. 1.16) approx. 76 approx.

Soil thickness 0.3 m (max. 91) per 1.17 1-3

Pump flow rate 90 u'/h I I I max. 11

90.e0 

S40 ..................................... Ca No2

80..... ...............................................................

604( ............................................................... 30 ................................

'(5 ........................... ...... .... ..... ... °...°...... ..... ...

40 ............................................................... 20 .............................- !................. ................ 30] ........................................................ ...... ,A v ., .

10 4

0 30 60 90

Trum (x58EC) Time(X5SEC)

Figure 27. Time series graph of Figure 28. Time series graph of

solid concentration environmental

turbidity

117
Figure 29. Exterior view Figure 30. Sampling of dredged

soil

OUTLINE OF EXECUTION OF REAL WORK

outline of Dredaina Operation

As a real work, the maintenance dredging of the anchorage area in from

of the coal unloading quay was carried out in Port of Onoda, Yamaguchi Prefecture. Dredged soil was loaded on a box barge and transported by sea to the

disposal area. The dredging operation executed was as follows:

a. Term of work: May/September 1991.

]. Type of dredging soil: clayey (about 200 percent natural water

content).

S. Dredging depth: 7.5 m (design).

g. Dredging volume: 47,600 m3 .

Change of Setup to Platform Car Shiftina System

Since the area to be dredged was a part of harbor, the influence of wave

and current was taken into account. Thus, instead of the previous maneuvering

method using spud pontoons, the platform car shifting method was chosen. Its

method was to run a platform car mounted with the dredging equipment in the

opening at the center hull of the dredger. The dredger wa maneuvered by means

of two anchoring wires and two sets of spud systems installed on its port

side. Figure 31 is a general arrangement plan of the dredger. Figures 32

and 33 show the situation of dredging operation.

Results of Work

Because of the passage of entering and departing ships in the dredging

area, the dredges had to shunt frequently and needed repeated positioning.

However, the adoption of an automatic tracking laser positioning system helped

to execute the work relatively smoothly.

The discharge hose had minor trouble. There were several large obstacles such as fishing nets and rocks, and removing them from the obstacle

remover also took time. Nevertheless, the system displayed a capacity

118
Platform Oac Operating room

Spud • 1support -

I .. piein, Operating

• ' __Transfer pump•

0 0

S40I000

Figure 31. General arrangement

Figure 32. External view Figure 33. Discharge of dredged soil

comparable to the efficiency set in the execution plan (dredging volume per

operating hour: 45 m3 /hr), and the work was completed within the scheduled

term.

119
CONCLUSION

The creation of desirable waterside residential areas is an important

environmental problem not only in the U.S. and Japan but in the whole world.

It is very important that the two countries continue to exchange technical

information on an even larger scale with the aim of advancing the technology

in sludge dredging and bottom sediments cleaning.

120
PHYSICAL SEPARATION TECHNIQUES FOR CONTAMINATED SEDIMENT

J. P. Allen, I. G. Torres

Salt Lake City Research Center

Bureau of Mines, U.S. Department of the Interior

Salt Lake City, Utah 84108-1283

ABSTRACT

Savings in the overall cost of environmental remediation can be expected when

low-cost mineral processing techniques are used to reduce the volume of contaminated material requiring expensive contaminant destruction or controlled

disposal. Mineral processing methods do not destroy contaminants, but they

can concentrate the pollutants in a smaller volume of material. This volume

reduction can make a subsequent destruction technology more efficient or economical, or reduce the cost of disposing of the sediment in a controlled

facility.

The Bureau of Mines, U.S. Department of the Interior, in cooperation with the

Great Lakes National Program Office, U.S. Environmental Protection Agency, has

conducted a study of mineral processing methods for remediation of contaminated sediment. The study sediments, from rivers and harbors on the Great

Lakes in the United States, c.ntained varying, but relatively low, levels of

heavy metal contamination, along with organic contaminants such as polychlorinated biphenyls (PCBs). The Bureau conducted investigations in size classification, magnetic separation, gravity separation, and froth flotation to

concentrate contaminants. The most effective application of mineral processing technology, on Saginaw River sediment, was the use of size classification

to isolate metal and organic contaminants. Froth flotation was also found to

be effective on organic contaminants.

INTRODUCTION

Background

This research was performed under an interagency agreement between the Bureau

of Mines (Bureau), U. S. Department of the Interior, and the Great Lakes

National Program Office, U. S. Environmental Protection Agency (EPA). Funding

was provided by the EPA. This work is part of the Assessment and Remediation

of Contaminated Sediments (ARCS) program authorized by the U.S. Congress in

the Water Quality Act of 1987.

The five Great Lakes are the United States' largest freshwater resource. In

fact, they contain 18 percent of all of the world's fresh surface water. Yet

through the years, the

pollution of the Great Lakes has become legendary. In the past decade,

remarkable progress has been made on improving Great Lakes water quality, and

the quantity and diversity of life in the lakes is increasing. Encouraging as

this is, the legacy of years of pollution remains in the contaminated sediments beneath the rivers and harbors feeding into the Lakes. These sediments

121
continue to be a source of contamination in the Great Lakes long after point

sources of the pollution have been identified and eliminated.

The pollution in the Great Lakes has come from the widest imaginable range of

sources, and includes heavy metals such as arsenic, chromium, and lead, inorganic pollutants such as nitrates and phosphates, and organic contaminants

such as PCBs and polynuclear aromatic hydrocarbons (PAHs). The Bureau's program initially focused on heavy metal contamination, but now includes the

organic contaminants as well.

To address the problem of contaminated sediments, the United States and Canada

have jointly identified 41 sites around the Great Lakes as Areas of Concern.

Under the Water Quality Act of 1987, the U. S. Congress has commissioned the

EPA, through the ARCS program, to study the effects of polluted sediment and

identify remediation strategies at five priority Areas of Concern. The Bureau

has performed characterization and mineral processing evaluations on samples

from four of the five priority Areas of Concern.

Sediment Samples

Examples in this paper are from tests performed on samples of contaminated

sediment from the Saginaw River, in Michigan on Lake Huron. Analysis of this

sample is shown in Table 1. For comparison purposes, Table 1 also presents

analyses of the other three sediment samples studied by the Bureau: sediment

from the Ashtabula River, in Ohio, and from the Buffalo River, in New York

(both on Lake Erie), and sediment from the Indiana Harbor Ship Canal, part of

the Grand Calumet River system in Indiana (on Lake Michigan). The Indiana

Harbor sample is the most polluted, followed by the Ashtabula, Buffalo, and

Saginaw samples.

122
Table 1. Chemical Analyses of Contaminated Great Lakes Sediments

Analysis, parts per million, dry weight

Indiana Harbor

Constituent Ashtabula River Buffalo River Ship Canal Saginaw River

Antimony NA* 2.4 7.8 NA

Arsenic 16.1 10.3 30.8 5.6

Barium NA 140 197 NA

Cadmium 6.5 2 8 4

Chromium 76 60 440 160

Copper 81 70 278 78

Iron 30,800 20,700 142,000 14,000

Lead 132 100 830 41

Mercury 0.57 0.47 0.74 0.22

Nickel 31 37 94 61

Selenium NA 0.37 1.59 NA

Silver NA 0.27 2.7 NA

Zinc 603 167 3,280 273

Total PCBs NA 0.4 0.2 6

Total PAHs NA 5.6 96 3.1

Oil and grease 17,300 5,000 58,000 3,000

Not analyzed.

123
Mineral Processing Technology

The Bureau's contribution to the ARCS program is to evaluate the application

of mineral processing (or physical separation) technologies to removal of low

levels of contamination from large volumes of sediment. Physical separation

techniques are widely used in the mining industry to recover valuable minerals

or metals from ores. Methods such as size classification, magnetic separation, gravity separation, or froth flotation, collectively known as mineral

processing, can be applied in some cases to separate contaminants from the

bulk of polluted sediment. The objective is to reduce the volume of

contaminated material requiring treatment by concentrating the contaminants,

in the same way an ore is beneficiated. This concept is very familiar to the

mining industry, but is new to the field of contaminated sediment remediation.

Since these methods are economically applied on a very large scale to ores of

low value-to-mass ratio, they are among the least expensive processes in modern industry. An example is a copper flotation mill that may be capable of

profitably treating more than 100,000 tons per day of ore that contains only

$10 worth of copper per ton.

As applied to an environmental remediation situation, such as contaminated

sediments, a few important points about mineral processing technology should

be remembered. First, mineral processing makes particle-particle separations.

No chemical bonds are broken, and no phases are destroyed. This is in contrast to many other remediation technologies, where a process such as incineration actually destroys the contaminant. Second, mineral processing

separations are based on differences in the physical properties of particles,

so that no separation can be achieved if all particles are physically similar.

Third, mineral processing is usually a high-capacity operation. Since most

ores processed contain low levels of valuable metal, this technology must have

a low cost per unit of mass processed. For example, in processing copper,

five or six separate mineral processing operations will be performed, plus

smelting and refining, all on an ore that contains less that $10 worth of

copper per ton. Finally, the capacity and efficiency of most mineral processing operations decreases with particle size.

A few contractors offer pretreatment or "soil-washing" technologies, usually

consisting of one or more mineral processing operations. Best results will be

obtained when the pretreatment system is chosen based on a detailed knowledge

of the physical and chemical characteristics of the sediment. The mineral

processing unit operations appropriate to the physical characteristics of the

sediment can then be arraiged into an integrated system. Bench-scale mineral

processing testing to verify performance is inexpensive, and scale-up reliability is well documented.*

Sediment Characterization

Detailed characterization of the physical properties of the sediment will

determine the selection of a mineral processing method or methods. Characterization includes (1) particle size analysis using sieves, hydrocyclones,

* N. L. Weiss, ed. 1985. SME Mineral Processing Handbook. Society of

Mining Engineers of the American Institute of Mining, Metallurgical, and

Petroleum Engineers, New York.

124
sedimentation, with chemical analysis to determine distribution of contaminants; (2) mineralogy, or identification of chemical phases, using scanning

electron microscopy with energy-dispersive techniques, and possibly x-ray

diffraction; (3) density measurements using the helium pycnometer, and sinkfloat separations in dense media; (4) magnetic separability, using highintensity wet and dry separators; and (5) evaluation of surface properties

applicable to froth flotation using zeta potential measurements and microflotation tests. Equally important is a knowledge of the history of the contaminated site which could provide clues about the nature of the contaminantbearing phases.

If discrete phases containing contamination have been identified, an appropriate mineral processing method can be selected. Mineral processing methods are

selected to exploit differences in the known physical properties of the phases

found to be present. For example, if most of the contamination is found to be

associated with the fine silt or clay particles, a size classification technique is appropriate. At one Great Lakes site, the sediment was found to

contain a large proportion of magnetic iron ore. Selection of a magnetic

separation technique may allow this material to be separated from the contaminated sediment and recycled to the steel-making process.

125
RESULTS AND DISCUSSION

Size Classification

Size classification is the cheapest and simplest technique that could be

applied to sediments. Size classification would be employed when a size chemistry analysis shows that a significant amount of the contamination is associated within a specific particle size range. Particle size separations down to

0.5 micron can be performed. Equipment used includes trommels; fixed, rotating, and vibrating screens; spiral, rake, and drag classifiers; and hydrocyclones.

The potential of size classification for contaminant removal is evaluated by

separating samples of the sediment into several size fractions, and analyzing

each for contaminants. The data can be plotted, as in Figure 1, to show the

amount of contamination found to reside in particles finer than a given size

as a function of the mass associated with those same particles. If the contamination is evenly distributed through all particle sizes, the graph wi.ll

show a diagonal line from lower left to upper right. These data from the

Saginaw River sediment show that chromium, lead, nickel, and PCB contamination

are strongly associated with the fine particles, so that more than 80 percent

of the PCBs are associated with the finest 20 percent of the sediment.

A separation of fine from coarse particles would typically be performed using

a hydrocyclone. Tests to determine the suitability of hydrocyclone for pretreatment of sediments have been conducted in the

laboratory using cal- 100-

ibrated sieves.

Appreciable reductions in these con- 80-

taminants for Saginaw

River sediment were WUL

achieved in a clean WComI u

sand product amount- 60 - ing to 81 percent of Lead

the sediment mass, -

and the contaminants -j 40- Nickel

were concentrated in A

the remaining 19 per- PCB

cent of the mass.

These data are shown 20-

in Table 2.

Particle size separa- - 0 I *

tion in a hydro- 20 40 60 80 100

cyclone occurs CUMULATIVE PERCENT TOTAL MASS

rapidly based on the

terminal settling Figure 1. - Partitioning of contaminants by size separation of Saginaw River

velocity of particles Sediment.

in water in a centrifugal field. The

slurry of sediment (usually 10 to 25 percent solids) enters the device

126
Table 2. Removal of Contaminants from Saginaw River Sediment

by Particle Size Separation

Untreated Sand Silt

Sediment >75 m <75 m

Analysis Analysis Distribution Analysis Distribution

Constituent ppm ppm pct ppm pct

Chromium 161 79 40 516 60

Lead 51 18 28 197 72

Nickel 65 27 34 230 66

PCB 18 4 18 77 82

Total mass 81 19

tangentially at high velocity, creating a swirling flow pattern. The larger

(and, therefore, heavier) particles settle outward and travel down the wall of

the device, exiting through the bottom apex. Smaller (lighter) particles are

carried with the water to the core of the cyclone and exit at the top.

Twenty-three-centimeter hydrocyclones, separating at about 75 microns, were

used in an ARCS program demonstration project at Saginaw Bay, Michigan.

Hydrocyclones are the most popular size classification device because of their

simplicity and high capacity. Hydrocyclones up to 90 centimeters in diameter,

treating several thousand gallons of slurry per minute, are commonly used.

Arrays of 66-cm hydrocyclones are used to treat copper ore at a mine in Utah.

Gravity Separations

Gravity separations also have applications for contaminated sediments. Frequently, organic contamination is associated with solid organic material or

detritus. These particles have much lower density than the natural mineral

particles of the sediment. Heavy metal contaminant phases would be significantly more dense than the natural mineral particles. Gravity separations

work best on particles larger than 75 microns, but separations among particles

as small as 10 microns can be achieved at low capacity with certain equipment.

Equipment commonly used includes dense medium separators, jigs, shaking

tables, flowing film concentrators, centrifugal separators, and elutriators.

Water elutriation, a gravity separation method employing a rising water current opposing the free settling of sediment particles, was evaluated to further clean the sand fraction from hydrocyclone separation of Saginaw River

sediment. It is shown in Table 3 that PCB levels could be reduced to

0.3 parts per million (ppm) by removing only about 2 percent of the remaining

sand. This was the low-density material that followed the rising current of

the elutriator and was carried over the top of the device. This is an example

where mineral processing operations can be combined to produce the desired

result.

127
Table 3. Further Removal of PCBs from Saginaw River Sand

by Water Elutriation

Sand Light Product Dense Product

Analysis Analysis Distribution Analysis Distribution

Constituent ppm ppm pct ppm pct

PCB 1.2 41.1 74 0.3 26

Total mass 2 98

Froth Flotation

Froth flotation is used to process millions of tons of ore daily. Copper,

iron, phosphates, coal, and potash are a few of the materials that can be

economically concentrated by this method. It is based on manipulating the

surface properties of minerals with reagents so that the mineral of interest

has a hydrophobic (water-hating) surface, like wax. The minerals to be

rejected have, or are made to have, a hydrophilic (water-loving) surface.

When air bubbles are introduced, the hydrophobic minerals attach themselves to

the bubbles and are carried to the surface and skimmed away. Flotation has

been successfully applied to particles as small as 10 microns. Almost all

flotation is conducted in stirred, aerated tanks of up to 56 cubic meters,

although vertical columns and air-sparged hydrocyclones are used occasionally.

When using flotation to remove oily contaminants from sediment, the role of a

surfactant more closely resembles that of a detergent. Most organic contaminants are naturally very hydrophobic, and the objective in using a surfactant

is to reduce the oil phase's hydrophobicity to the point where it will be

wetted by the water phase and detach itself from solid surfaces. Surfactants

are able to accomplish this because such molecules have a lipophilic (fatsoluble) head, which is absorbed into the oil phase, and a hydrophilic tail,

which extends into the water phase. The result of this is that the overall

hydrophobicity of the oil phase is decreased. The strength of a surfactant's

attachment to an oil phase is approximated by the hydrophile-lipophile balance

(HLB) of the surfactant. Once freed of the solid surface, an oil droplet is

assisted to the surface by air bubbles and skimmed away.

A variety of surfactants have been selected, based on their detergent properties, for investigation with contaminated sediments. A number of different

surfactants have been used by the Bureau in this study for removing organic

contamination from river sediment. The most promising appear to be ethylene

oxide-based amine and alcohol surfactants.

In our research for the ARCS program, froth flotation is showing promise as a

means for recovering organic contamination from sediment. In much of our

organic work, the oil and grease analysis is used as an indicator parameter

for organic contaminants. Preliminary results show that considerable reductions in organic contamination, to less than 100 ppm oil and grease, are

achieved by separation of an organic-laden froth, or concentrate. The results

also show that this contamination can be concentrated in a small volume, from

11 to 26 percent of the original mass, by a single stage of flotation.

128
Table 4 gives results of flotation tests on Saginaw River sediment. The most

satisfactory results, based on the oil and grease analysis of the tailings,

were obtained at neutral or alkaline pH. To verify conclusions drawn from the

oil and grease analyses, products from two of the tests were reanalyzed for

total PCBs. These additional data indicated comparable separations to the oil

and grease results.

Table 4. Removal of Organic Contamination from Saginaw River Sediment

by Froth Flotation Using Triton Surfactants

OiL & Oil & Oil &

Mass PCs Grease Oil & Grease PCB Grease Grease

Triton Distribution AnaLysis Analysis Distribution Analysis AnaLysis Distribution

Surfactant* pH pct ppm pIN pct ppW ppm pct

RW-150 4 11 NA 27,575 96 NA 144 4

RW-150 7 19 622 15,946 97 0.71 106 3

RW-150 10 18 NA 1,561 93 NA 2593

RW-50 4 24 NA 1,821 76 NA 178 24

RW-50 7 26 312 12,038 97 1.1 125 3

RW-50 10 15 WA 1,588 94 NA 19 6

X-114 4 20 NA 16,356 97 NA 137 3

X-114 7 19 NA 16,441 96 NA 183 4

X-114 10 15 NA 1,758 96 NA 12 4

* Triton RW-50 and 150 are mine ethoxyLates with 5 and 15 motes, respectively, of ethylene oxide per mote

of surfactant. Triton X-114 is an octytphenoL ethoxyLate with an average of 8 moles of ethylene oxide

per mole of surfactant. Surfactant concentration in all tests was 0.1 wt pct in solution.

' Initial PCI analysis was 18 ppe.

Pretreatment Process Costs

The cost savings associated with mineral processing pretreatment of

contaminated sediment are dependent on the amount of volume reduction. In

other words, the amount of unpolluted material that can be separated out of

the sediment, the cost of pretreatment, and the cost of ultimate treatment (or

disposal) all affect the economics of pretreatment. The total cost for dealing with polluted sediment is the sum of the cost of pretreatment on the

entire sediment volume, plus the cost of treating the concentrated polluted

fraction.

In making a decision to investigate pretreatment, one can require that the

ratio of the total cost per unit volume (including pretreatment) to the cost

per unit volume of ultimately treating the contaminated material must be less

than one. In other words, it must be less expensive to pretreat the entire

volume, and then treat the reduced volume of contaminated material, than it is

to simply treat the entire volume of sediment without pretreatment. As an

example, if the cost of pretreatment is $50 per cubic meter, and the ultimate

remediation cost (e.g., incineration) is $250 per cubic meter, then the needed

volume reduction is 50/250 or 0.2. If pretreatment could reduce the volume

requiring incineration by greater than 20 percent, then a savings in the overall cost of dealing with this contaminated sediment could be achieved.

129
requiring incineration by greater than 20 percent, then a savings in the overall cost of dealing with this contaminated sediment could be achieved.

SUMMARY

Mineral processing technology is available from several vendors and

contractors throughout the world. Remediation-oriented companies have offered

some mineral processing technologies under the title of "soil-washing." In

May 1992, the ARCS program demonstrated pretreatment of Saginaw River sediment. The on-site processing plant was provided by a private contractor, and

was centered around three stages of hydrocyclone size separation, separating

PCB-contaminated fines from relatively clean sand. The plant also included

size separations by trommel and by vibrating and rotating screens. Also available were a hindered settling gravity separation unit and attrition scrubbers

for removing surficially bound contamination. Results of the demonstration

will be available in 1993.

Mineral processing pretreatment methods do not destroy contaminants, but they

can reduce the volume of sediment requiring more extensive or expensive treatment. For successful application, the contaminants to be removed must reside

principally in a physically separable phase (or phases). This physically

separable phase can be characterized by differences in grain size, density,

magnetic susceptibility, or surface properties from those in the bulk of the

sediment. Also, this phase must represent a sufficiently small fraction of

the sediment, so that the volume reduction achieved justifies the cost of

mineral processing pretreatment. Finally, it must be less expensive to treat

a smaller volume of concentrated contaminated sediment than it would be to

treat the entire volume at lower contaminant concentrations. Detailed grain

size analysis, size chemistry, and mineralogical characterization, followed by

bench-scale testing, are the methods for determining if a sediment meets these

criteria.

130
INTRODUCTION OF NEW METHOD OF DISPOSING DREDGED MUDDY SOIL

WITHOUT DISTURBING MARINE ENVIRONMENT

Hiroyuki Sakamoto, Tadaomi Fujisaku, Masao Shimoda,

Kazuo Ishiguro

Japan Sediments management Association

15 Sankyo Bldg, 2-7-12, Tsukiji,

Chuo-ku, Tokyo, 104, Japan

ABSTRACT

A new method of disposing dredged muddy soil has

been developed to make use of the dredged sludge while

preventing pollution arising from the treatment of

sludge from affecting the fishing industry. In order

to prevent pollution from occurring by mixing the

sludge with the solidifier and placing it underwater,

the method of placing and the fluidity of the treated

sludge become vital factors.

In this report, an outline of this new nonpolluting method of treatment is introduced along with

the preliminary experiment and onsite prototype experiment results of this method. In the preliminary

experiment, tests of the performances of the solidifier of cement origin especially developed for this

method and the experiment on the method of placing

underwater are introduced. The onsite experiment

involved an experiment of the method of placing underwater using a prototype, a practical-level machine.

The following gives the results obtained from these

experiments.

A. The fluidity of the new solidifier was excellent

compared with ordinary portland cement and

quicklime.

1. In the preliminary experiment, the method of

placing underwater was tested, and the interior of

the treated sludge was found closely packed.

c. The onsite demonstration showed that underwater

placing could be carried out with almost no effect

on the water quality.

INTRODUCTION

In recent years, removing sludge which has accumulated in the seas,

lakes, swamps, and rivers had become a social problem requiring quick action

because it deteriorates the water quality of various regions, obstructs ships

and gives rise to other problems. However, the present status is that public

131
dredging works have not progressed as scheduled because of a deficiency in the

number of places for depositing or treating dredged sludge. Under this circumstance, we have developed a nonpolluting method of treating sludge which

would solve such space problems for dredged sludge. Here, the sludge is mixed

with cementious solidifier (sludge mixed with cementious solidifier will be

hereinafter called treated sludge). Then, the sludge is placed underwater

before it hardens in a manner such that pollution is kept to an absolute minimum. The material can be fully utilized for reclamation, thus resolving the

problem of a lack of space for depositing on treating dredged sludge.

The distinctive feature of this method is that it hinders the dissociation of the treated sludge in the water as much as possible,m eliminating

water pollution caused by the hardening in the water.

In order to accomplish the above purposes, we have developed a new unit

for underwater placing and cementious solidifier.

This report gives (a) an overview of this method of treatment, (b) part

of the descriptions of experiments conducted to confirm the performance of the

solidifier newly developed for this method, and (c) the results of the demonstrations performed by using a manufactured prototype, acting as a practical

unit.

OVERVIEW OF THE METHOD

Figure 1 shows a conceptual plan. In this method, after the workability

of the dredged sludge has been adjusted, it is mixed with a cementious solidifier. Then, after giving it an adequate fluidity, an underwater placing unit

is used to place the material to the sea bed. It was ensured that at the time

of placing, the discharge opening of the underwater placing unit is always

preinserted in the treated sludge. With this technique, and the use of the

new solidifier, which prevents the dissociation of the sludge, permit placing

of underwater with hardly any diffusion of pollution in the water. The system

configuration of this method of treatment is as follows: (a) pneumatic conveying plant, (b) workability adjuster, (c) solidifier mixing unit, (d) underwater placing unit, and (e) monitoring and measuring instruments and cementious solidifier. This solidifier especially developed for this method was a

unique characteristic, featuring fluidity, resistance to dissociation and

deodorizing characteristics.

Workability adjuster Underwater placing unit

Uni fo litn Mixing unitSeato

up mud • •• Conveying plant

nit fo liftig a or

Treated sludge

Figure 1. Conceptual plan of the method of treatment

The procedure for the method is as follows:

A. The workability of the dredged sludge is adjusted.

132
k. Based on the indoor test conducted beforehand, the required amount

of solidifier is added to the sludge. Then, a continuous mixer is

used to stir and mix them.

.S. A conveying plant is used to convey the sludge treated with the

solidifier through pipes up to the barge where an underwater placing

unit is located at the site of reclamation.

•. After the dissociation of air, treated sludge conveyed by the conveying plant is supplied continuously by conveyor pumps top the

underwater placing unit. This unit features a discharge opening

unit with built-in auger. Then, the supplied sludge is placed

underwater. For on land works, a conveyor pump is used for direct

installation.

DEVELOPMENT OF SOLIDIFIER

The development of the solidifier necessitated research on the following

major aspects:

j. To reduce dissociation of the treated sludge during underwater

placing.

k. To maintain fluidity of the treated sludge during underwater

placing.

p.. To maintain hardening strength under water.

A. To improve deodorizing effect on the sludge.

By maintaining the fluidity of the treated sludge, the treated sludge

can be moved smoothly during underwater placing operation. At the same time,

its combined effects with the increased resistance to dissociation of the

sludge eliminates muddiness, prevents pH increase during underwater placing

operation, and also secures continued strength.

TEST ON FLUIDITY OF THE TREATED SLUDGE

In order to test the fluidity of the treated sludge, flow tests of ordinary portland cement (hereinafter called O.P.C.), quicklime and the newly

developed solidifier (hereinafter called S.C.) were conducted based on a flow

table u:,ng instruments employed in the JIS R 5201, "Physical Testing Methods

for Cement."

Setting Conditions

Three types of solidifier, namely S.C., O.P.C., and quicklime were added

to the dredged sludge in powder form. In addition, water was added to the

S.C. and the O.P.C. in a one-to-one ratio to produce solidifier slurry (S.C.

slurry hereinafter called S.C.S and O.P.C. slurry hereinafter called

O.P.C.S.), which were also added to the dredged sludge. The solidifier was

added in a 3, 5, and 10 percent ratio by weight with respect to the wet sample

sludge. The kneading time using a Hobart-type mixer was ten minutes.

133
In the flow test, the fluidity was measured just after kneading, 7 min

after kneading, and 15 min after kneading.

The sample sludge was taken from the bed from the Bay of Shiofama at the

center section of the bay using an Eckman barge mud collector. Table 1 shows

the properties of the sample sludge. Note that in the test, water content of

the sample sludge 'v' was adjusted to 250 and 300 percent.

TABLE 1. SOIL PROPERTIES OF SAMPLE SLUDGE DURING

FLUIDITY TEST

Factor Measured Value

Specific gravity of soil particle 2.644

Grain size distribution

Gravel fraction (2-75 mm) % 0

Sand fraction (75 pm-2.0 mm) % 3.2

Silt fraction (5-75 pm) % 40.8

Clay fraction (under 5 pm) % 56.0

Maximum grain size mm 2.0

Liquid limit 146.0

Plastic limit 58.9

Plasticity index 87.1

Water content 264.9

Wet density g/cm3 1.233

Void ratio 6.825

Degree of saturation 102.6

Test Results and Observations

Figure 2 presents the flow test results of the treated sludge when the

types and ratio of the solidifier added were changes. figure 3 fives the flow

values resulting from the addition of the powdered O.P.C. and S.C., and the

slurry.

Comparing the effects of the solidifier type on the flow value in Figure 2 indicated that S.C. had a higher flow value than O.P.C. As the ratio of

S.C. added increased from 3 to 5 percent, the flow value dropped slightly

while it increased as the ratio increased from 5 to 10 percent. This behavior

is explained by the increased amount of fluidizing agent contained in S.C.

The O.P.C. showed almost the same trends, except that the flow value decreased

in the 3 to 10 percent range. The flow value of the quicklime decreased

almost in a straight line as the ratio increased, increasing the ratio of the

quicklime reduced its flow value, which was less than that of O.P.C.

According to Figure 2, increasing the ratio of S.C.s and O.P.C.s added

increased the flow values. This increase occurs essentially because the added

material is a slurry produced by an addition of an equal amount of water to

the solidifier by weight. The S.C. exhibited virtually the same increase as

that of S.C.s up top a ratio of 5 percent. Its flow value, however, dropped

134
210

0..---- .0: S.C(Otiq) t ------4: 0. P.C|(Gain)

&-----6 S.CTmi) a, -•:O.F.C Raim) ..

•--o. S.C(~Iaoin I----: O.P.C(IL-ia) - - -"

0- - S.C.S (bmi O" -

6----6 S.C.S(Ioin) ' - - .- -- o $.C.S(I~ui.) ,' -- ---- - "B

S0--4. O.P.C-S Mim) ' " 200-- _____________________________o ---. : O.P.C-S(?.miaR) l,I:r -.

AS.C(Taia)

103 0

It aO icklimle(ial 14

( O.P.C(siae)

a O.P.C(?.II)

180 O.P.C(Iki. 90

155 -

Soliifie conentSolidifier content

Figure 2. Flow test results when Figure 3. Relationship between the

types and ratio of ratio of solidifier added

Solidifier changed and the flow values

resulting from addition

of O.P.C., S.C., and

slurry

below 5 percent when the added ratio reached 10 percent. In comparison, the

flow value of the O.P.C. stayed about the same or dropped slightly even when

the ratio increased.

In Figures 2 and 3, the numbers in brackets indicate the standing time

after kneading. The effects of time elapse after kneading on the flow value

were tested by taking measurements up to 15 min of time elapse. The test

showed that the flow values increased with increasing time elapse after

kneading. On the other hand, O.P.C. and O.P.C.s showed a decrease in the flow

values with increasing time elapse. This decrease is believed to be caused by

the effects of the fluidizing agent contained in S.C.

PRELIMINARY UNDERWATER PLACING EXPERIMENT

The possibility of placing the treated sludge in the water and the hardening strength during underwater placing were determined.

Testing Method

In the test. a model of the underwater pipe incorporating a 100-mm diam

auger illustrated in Figure 4 was used to place the treated sludge in a waterfilled 4200- by H300-mm acrylic tank. Then, this condition was preserved for

135
(0)

SNMotor

Hopper

4{

Auger <

< ~Iw

Figure 4. Installation unit model

three days. A 050- x H100-mm specimen for the unconfined compression test of

the sample of treated sludge prepared in the air based on the Soil Engineering

Standard, "Practice for Making and Curing Noncompacted Stabilized Soil Specimens," was carried out. The unconfined compression test was carried out by

conforming to JIS A 1216.

Setting Conditions and Sample Sludge

Table 2 gives the conditions for setting for installation both in the

water and in the air. The ratio of the solidifier added to the dredged sludge

was defined in terms of the wet dredged sludge by weight. During underwater

installation, this ratio was set at 4 and seven percent while, in the air,

this ratio was 4, 7, and 10 percent. Table 3 presents the properties of the

sample sludge, which was taken at the sea bed from the Bay of Shiogama at the

center section of the bay.

TABLE 2. SETTING CONDITIONS

Setting for Installation Water Content (%) Solidifier Content (%)

300 4

In the water 325 4

350 4,7

300 4,7,10

In the air 325 4,7,10

350 4,7,10

375 4,7,10

136
TABLE 3. SOLID PROPERTIES OF SAMPLE SLUDGE DURING

UNDERWATER INSTALLATION

Factor Measured Value

Specific gravity of soil particle 2.547

Grain size distribution

Gravel fraction (2-75 mm) % 0

Sand fraction (75 pm- 2 .

0 mm) % 5.0

Silt fraction (5-75 pm) % 24.0

Clay fraction (under 5 pm) % 71.0

Maximum grain size mm 4.76

Liquid limit 165.4

Plastic limit 43.9

Plasticity index 121.5

Water content 200.1

Wet density g/cm3 1.259

Void ratio 5.069

Degree of saturation 100.5

Test Results

Tables 4 and 5 and Figure 5 show the results of the unconfined compression test of the treated sludge. Almost no differences were observed

among the average values of the unconfined compressive strength. However, the

scatterings of data for the unconfined compressive strength during installation in the water were large. The strength at the lower part of the test

piece during installation in the air was high while that of the upper part was

low compared to those done in the water. The installation condition is illustrated in Figure 6. Virtually no treated sludge dissociated or diffused in

the water during installation. No muddiness was produced. The condition of

the sample after installation in the water is illustrated in Figure 7. Cracks

can be seen on the upper 2 to 3 cm where water immersed. However, the lower

part of the treated sludge, which was densely packed, was an excellent solid.

ONSITE PROTOTYPE EXPERIMENT

In the experiment, sludge dredged from the Bay of Shiogama in

Shiogama-City, Miyagi prefecture, was used. The experiment of the treatment

of the dredged sludge by mixing solidifier was carried out: (a) to find out

its suitability for allowing reclamation in the water, (b) to find out its

effects on the performances of the solidifier and water quality during

placing, and (c) to understand its executability as a total system. A smallscale practical-level prototype was developed to conduct a large water tank

test and installation experiment in the water.

137
TABLE 4. UNCONFINED COMPRESSIVE STRENGTH DURING INSTALLATION IN THE AIR

Unconfined Compressive

Water Content Solidifier Content (k~ f /m2) Strength

Test No. (%) (%) 7-day 28-day

4 1.42 1.62

1 304.3 7 2.63 3.94

10 1.99 4.23

4 1.21 1.67

2 326.4 7 2.47 3.88

10 2.20 4.40

4 1.10 1.52

3 354.5 7 1.07 3.18

10 1.90 3.45

4 1.33 1.38

4 379.7 7 1.75 2.80

10 1.90 3.45

TABLE 5. UNCONFINED COMPRESSIVE STRENGTH DURING INSTALLATION IN THE WATER

Water Solidifier Unconfined Compressive Strength

Test Content Content (kjf/cm2) 7-Day

No. (%) W 1 2 3 Average

5 302.6 4 1.60 1.45 0.95 1.33

6 325.8 4 1.55 1.45 0.95 1.32

7 348.1 4 1.72 1.64 -- 1.68

8 345.2 7 2.20 2.10 1.60 1.97

138
5

4 1O%.28-day

02 7%28day

w3

. 7%. ?-day • • 02

E0~7% 10-dayda o In the water 7%

• 2-4%, 28-day

r! C

NIn thwe 4water 4%

1 ~4%, 7-day

0 I I I I

300 325 350 375

Water content w (M)

Figure 5. Relationship between the Figure 6. Conditions for

unconfined compressive installation

strength and the water

content ratio

Figure 7. Conditions for installation in the water

139
Large Water Tank Experiment

Unit for Experiment

The experiment was conducted using the system shown in Figure 8. Figure 9 illustrates the experimental condition. The system of this unit has a

placing capability of 35 m3/h. The system comprises a unit for lifting up

mud, workability adjuster, pneumatic conveying plant, mixing unit, and unit

for underwater reclamation newly developed for this method. the unit for

underwater reclamation includes a separator, unit for stirring and mixing, and

an underwater placing unit. The following gives an outline of each component

unit.

Track crane

Separator

Underwater placing unit

Continuousmie

Unit for addition Pneumatic conveying

of solidifier plant Tank for stock

Sand carrier

Figure 8. Conceptual plan of the experimental system

IFigure 9. Condition of large water tank experiment

140
A. Separator. Separated the high-pressure air used during compression

and the dredged sludge to reduce the shock generated by compressed

pressure. It has a cyclone-type storage hopper featuring a controllable discharge mechanism.

k. Unit for stirring and mixing. Continuously stirs and mixes the

dredged sludge with solidifier.

.. Underwater Rlacing unit. Places the treated sludge in the water

without creating muddiness. Installation by free-fall cannot be

carried out because the density of the wet treated sludge during

underwater placing is only about 1.2 kg/cm3 and because it has adhesive properties. For this reason, a screw mechanism built in the

body is used to forcefully place the sludge. In addition, a switch

gear is mounted on the discharge opening to prevent the treated

sludge from falling freely in the water during the start of the

operation.

The system as described previously is used to place treated sludge in a

5- by 2-m large water tank. changes in the fluidity of the treated sludge and

the water quality during the placing operation were measured. The water tank

was filled with the Gulf water filtered beforehand.

Outline of Experiment

Table 6 indicated the conditions for the water quality measurement

experiment. In experiment numbers one to three, treated sludge was placed in

saltwater, and in experiment number 4, treated sludge was placed in fresh

water (tap water). In the experiment carried out in the saltwater, the water

content ratios of the sample varied considerably. This variation in the

ratios, however, results from adjustments made to vary the fluidity of the

treated sludge. Table 7 presents the conditions for measuring the water quality. As shown in Figure 7, water for measuring the water quality was obtained

as follows. Ten pipes for collecting water were installed in the water tank.

Then, a bellows quantitative pump was used to collect 100 ml of water for each

of all ten pipes once every two min from the 4 8-mm and 10-mm long stainless

pipe bent in an L shape employing a silicon tube. The turbidity and the pH of

the collected water was measured immediately after the experiment. Figures 11

and 12 five the conditions for setting the pipes used for collecting water.

TABLE 6. CONDITIONS DURING WATER QUALITY MEASUREMENT EXPERIMENT

Water Solidifier

Test Content Content Initial Water Placed Treated

No. (%) (%) Volume (W3) Sludge Volume (W3 ) Kind of Water

1 248.4 4 9.6 7.7 Saltwater

2 273.1 4 10.3 1.8 Saltwater

3 225.7 4 7.0 4.3 Saltwater

4 248.0 4 7.0 5.9 Fresh water

141
TABLE 7. CONDITIONS FOR MEASURING WATER QUALITY

Factor Condition

Number of collecting point 10

Frequency of collecting water Before installation,

Once every two minutes

Item of water measurement Turbidity (NTU), pH

Method of measurement Turbidity, pH meter

Underwater placins

4 7 9

S3 ,4 6

Figure 10. Figure indicating locations of water collection

Figure 11. Conditions for setting pipes for water collection

142
Figure 12. Conditions for setting pumps for water collection

Table 8 presents the soil properties during the experiment. Although

this sample was collected from the same place as where the preliminary experiment was conducted, it has a silt-and-clay combined content of 97 percent.

Its fluidity during placing was measured by taking pictures every 30 sec from

the start with a camera mounted on the front of the water tank by opening a

window, a transparent acrylic plate at the front part of the water tank.

TABLE 8. SOIL PROPERTIES DURING THE EXPERIMENT

Factor Measured Value

Specific gravity of soil particle 2.561

Grain size distribution

Gravel fraction (2-75 mm) % 0

Sand fraction (75 pm-2.0 mm) % 3.0

Silt fraction (5-75 pm) % 24.0

Clay fraction (under 5 pm) % 55.0

Maximum grain size mm 4.2

Liquid limit 150.8

Plastic limit 44.7

Plasticity index 106.1

Water content 160.0

Wet density g/cm3 1.305

Void ratio 4.123

Degree of saturation 100.

143
Result of Experiment

Figure 13 shows the changes in the form of the treated sludge with the

passage of time for each experiment. In the figure, the changes in the form

of the treated sludge are represented by continuous lines, dotted lines, and

dashed lines. Numbers one through nine at the side of the lines represent the

observation number of the treated sludge form performed every two min from the

start. Figure 13 shows that after the treated sludge ascends approximately

60 cm, it moves horizontally. For the ascending sludge, with decreasing water

content ratio, the starting height at which the sludge moved horizontally

tended to increase.

-4 43 2 1 4

S2040_300 500 500 500 f 600

_______________________________ - -II 

2 500

5 000

Figure 13. Changes in the surface of the treated sludge with time

(Sheet 1 of 4)

ea

9 I0

200 300 500 2500 500 500

S5~ 0 0 0 ,

Figure 13. (Sheet 2 of 4)

144
IT

98 12001 300l 1 $00 6... 00 500 50

2606

Figure 13. (Sheet 3 of 4)

t9* I IN m ,F 6560

32 00 3_00 500 500 500 50

6000 

0

Figure 13. (Sheet 4 of 4)

Figure 14 indicates the results of measuring water quality during the

observation of the form of the treated sludge. The results of pH measurement

showed that all number one points had an initial value of 7.76 and a maximum

value of 7.92 with an increase of 0.16. Note that the water-collecting inlet

was separated 15 cm from the surface of the treated sludge. At number 2, the

initial value was 7.89 and the maximum value 7.96 was an increase of 0.07.

Next at number 3, the initial value was 7.90 and the maximum 8.11 with an

increase of 0.21. Here, the distance from the water-collecting inlet to the

surface of the treated sludge was approximately 10 cm. Other points which

were measured at the same time had an increase of 0 to 0.04.

145
9

PH

8 ND ND

Measured point

*-- : I

: 2

~:3

7 .-- Q: 6

201 .• o----. : S

10... . ~10 ... .10

ND .......

Svo 2 4 6 8 10 12 14 16 18

Time (min)

Figure 14. Changes in the water quality with time

(Sheet 1 of 4)

PH[

8 __ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _

Measured point

S1

IS

20.

C6

00 2 4 6 8 10 12 14 16 18

Time (min)

Figure 14. (Sheet 2 of 4)

146
9

p H

ND

8N D = ND

Measured point

- : 1

" :-- 3

7L -.. :4

10. : N D

20 -------- - ---

0 2 4 6 8 10 12 14 16 18

Time (min)

Figure 14. (Sheet 3 of 4)

10-

pH

ND

8 D ND

Measured point

ý 1 7--4 : 2

"-: 3

- :4

60 -- : s p---4: C

•50 ..... :7

40 "".: ND 0---. :

410 ND

C9

2 4 6 8 10 12 14 16 18

Time (min)

Figure 14. (Sheet 4 of 4)

Number 4 represents the results of the test performed in fresh water.

The initial value was 7.69 and the maximum 10.18. However, the values of

numbers 2, 3, 5, and 6 had a high pH of at least 8 because of measurements

taken at a distance separating the water-collecting inlet and the surface of

the treated sludge by only zero to a few centimeters. This measurement may

have been caused because the sludge surface might have been touching the

inlet. At other points, the increase in the pH were slight, being 0.28 at

most.

147
The turbidity of the saltwater test numbers 1 through 3 had a maximum

increase of 11 Nephelometric Turbidity Units (NTU). However, this maximum

increase was observed twice only for test number 3. For other measures

points, the maximum was 5 NTU. Measurements were taken 1 to 2 cm directly

above the surface of the treated sludge. the turbidity increased by 0 NTU to

3 NTU at other points. The relation between the turbidity and the suspended

solids (SS) was obtained beforehand.

In the freshwater test number 4, the maximum was 65 NTU. this value,

however, corresponds to the measures point at which the pH was 8 or above

measured at a distance separating the surface of the sludge and the watercollecting inlet by zero to a few centimeters. Thus, the surface of the

sludge may have been touching the inlet.

Considering all the experiments carried out in saltwater, the average

increase in the pH was 0.027 with an insignificant maximum increase of 0.16.

The average increase in the turbidity was 0.83 NTU (equivalent to 0.93 mg/l

when converted to SS), and the maximum increase 11 NTU (12/3 mg/l when converted to SS), which were extremely small.

Measurements of the water quality at a place of 30 cm or more from the

surface of the treated sludge showed that the average increase in the Ph was

0.015 and the average increase in the turbidity 0.5 NTU, demonstrating that

there was almost no effect on the water quality. The relationships between

the distance separating the inlet and the surface of the treated sludge during

water collection and the increase in the turbidity are shown in Table 9. the

average increase was 2.37 NTU at distances ranging from 0 to 30 cm., 0.52 NTU

at 30 to 650 cm, and 0 NTU or 1 NTU for distances above 60 cm. the average

was 0.28 NTU meaning that there were almost no effects on turbidity.

TABLE 9. RELATIONSHIPS BETWEEN DISTANCE FROM THE SLUDGE SURFACE

AND THE INCREASE IN TURBIDITY

Distance From the Average of Increase Converted to SS

Sludge Surface (cm) in the Turbidity (NTU) (mg/l)

0-30 2.37 2.65

30-60 0.52 0.58

60< 0.28 0.31

Underwater Placing Experiment in Saltwater

An underwater placing experiment in saltwater, under conditions close to

the actual work, was performed.

Unit for Experiment

The unit used was the same as that employed in the Large Water Tank

Experiment. Figure 15 illustrates the layout used for the experiment. A

section measuring approximately 10 by 10 m was dug out to make a pond, in

148
IV0

C6

00

4- 0I14 r34) w 1

d) 4)

0

0 0

0

ca)

J9.

4) w r4

00

x 4..

"4.

4)149
which the experiment was carried out. An opening was made to let in

saltwater.

Outline of Experiment

In the experiment, the ratios of the solidifier added were 4 or 5 percent. The amount of treated sludge placed was approximately 39 mi. After the

operation, the form of the solidifier was observed and the hardening strength

of the collected cores determined.

Results of Experiment

Figure 16 illustrates the form of the sludge after the operation. The

sludge surface was fairly smooth. The run-off gradient was generally 1:5.

Solidifier content (%) 57.

4.50 (M)

0 A

.67 G 1: 

2.00 2.00 4.30

Solidifier content(%) 4%

Figure 16. Form of hardening materials

Table 10 shows the results of the unconfined compression test of the

core collected after the operation as well as those of the cone penetration

test. The unconfined compressive strength value virtually met the target

28-day strength of qu - 1.0 kgf/cm2 in 7 days. The relationship between the

unconfined compressive strength and the cone bearing capacity was qc - 6 to

13 qu.

CONCLUSION

The preliminary experiments and onsite prototype experiments showed that

the placing of the treated sludge in the water for reclamation using a unit

for underwater placement ca be carried out without deteriorating the water

150
TABLE 10. RESULTS OF STRENGTH TEST

Solidifier Content (t) 4 5

Depth (cm) 10-30 30-50 10-30 30-50

qc (kgf/cm2 ) 13.1 12.2 10.7 16.0

qu (kgf/cm2 ) 1.45 0.95 1.66 2.29

qc/qu 9.0 12.8 6.4 7.0

quality if satisfactory quality control and site control are maintained to

prevent dissociation of the material.

This method of treatment permits reclamation without deteriorating the

water environment. In addition, it enhances the effective use of the dredged

sludge by permitting the reclaimed ground to be used soon after reclamation.

We are planning to study the long-term effects on the environment and the

changes in strength and to develop a practical unit based on demonstrations.

151
RESTORATION OF LAKES AND MARSHES TO APPLY THE

TREATMENT OF BOTTOM SEDIMENTS USING

BIO-REACTOR (BIOTECHNOLOGY)

Hiroshi Kishi, Chief

Makoto Natori, Supervisor

Experiment Group of Rikuzen Takada City

Tatsuo Matsuno, Tadashi Owada

ABSTRACT

Marsh Furukawa in Rikuzen Takada City, Iwate

prefecture, is a considerably polluted marsh that is

caused by organically polluted bottom sediments. With

the prime objectives to improve the quality of the

bottom sediments and water, several experiments were

carried out by using bio-reactors, At first, dredged

polluted muddy water was treated by the bio-reactors,

and subsequently polluted substances were decomposed

and oxidized. This treatment succeeded in reducing

polluted substances and removing rot odor from the

bottom sediments; therefore, facilitating subsequent

treatments. Possibilities are found in the restoration of the self-purification functions of the marsh

by returning the treated bottom sediments to the

marsh, i.e. recovery of ecosystem. After the spillwater was treated, it also was discharged to marsh

Furukawa.

From the results of the series of experiments,

it was found that the principle subject for purification works could be carried out practically, i.e.,

obtaining disposal sites for the dredged bottom sediments. Following these experiments, larger scale

demonstration tests were conducted to improve the

polluted bottom sediments.

INTRODUCTION

With the direct purification method for lakes and marshes based on biotechnology, a series of tests were carried out to treat bottom sediments

(black colored rotten mud) and suspended sludges on the marsh. This treatment

helped to reduce and prevent rot odor of the mud and to facilitate further

treatments in subsequent steps. The objectives of the experiments were the

restoration of self-purification functions of the marsh and regenerations of

phytobenthoses and benthic animals.

MARSH FURUKAWA

Marsh Furukawa in Rikuzen Takada City, Iwate prefecture, is the biggest

natural marsh in Iwate and faces Hirota-bay in Rikuchu coast (Figure 1).

152
R s nTakada k c ty• S~ Koizuml river

Furukau amrsh k

toD

Fiue1 Bids-y view of mas Furukawa"

n Football fseld w bird,.an

to

embakinets onstuctd ere alng Tkad pin groes.marsh Furukawa bcm

a patly losdFwaerurea 1.Becaus-ee excanewae betee marsh Furukawa an

\ btutdatrtetd Hirota-bywr ebanknnswr cntutd

CosqetyMh Frkw arsh has beenis eurpiated, ara979000s sinc by, phsolluted sub-it

stne disch03.arged fverome iaten da City.

Inthe arasurondn marsh Furukawa hadlnyfsh bend dhesignated theds anrik

evn amos int en river. Pol enoe th eni nm t. I 190 af r

arias Resot" was ai pepl' resort waresaue in the Comuity. Teirtqae ethusas tise

embakmens cotrutedalon wee Takda pne gove. Mrsh Furukawabcm

a patly losd Fwaerurea i.becaus-eyechne wate r betee marsh Furukawaan

Conseqety theukmars has beenis wateranarea sinc 10,000s by phsolluted sub-it

stace d5ischm3argd fvromag w ue n ater Ceithyf .77

InThe parasurondn marsh Furukawa had lnyfsh bendesigaelswid btrds "andi

ianesrluoat" was ai pepl' resort waresaue in the cmuity. Teirthuaenthusas ide

indicated in the slogan, "Restoration of beautiful marsh and creation of the

marsh where people can study nature."

153
Water Ouality of Marsh Furukawa

Present water quality of the marsh in shown in Figure 2.

Vertical distribution of water quality

i. Test date 1987/01-Water temp. 6.1-10.50

ji. Central Part Water depth 2. 5 m

[m]

BOD 0.00oo

CO0D -- 0 0.25 _ý Y 'I --N

I E rt', I~: I_ I i i~jillif i __ _

T-N 0.50 Ji '_ _

T-P ---A X 0.75 4

0.1.-1 10 10 1 1 --- o I 11 1!. 

SS __A 1.00

D 01. 25

C f -- 0 . 50

Figure 2. Water quality of marsh Furukawa

The above figure indicates water qualities at each stage of every 25-cm

depth in the marsh for analyzing BOD (biochemical oxygen demand), COD (chemical oxygen demand), T-N (total nitrogen), T-P (total phosphorus), SS (suspended solids), DO (dissolved oxygen), and Cl (chloride) items. Marsh

Furukawa is classified as "B"-type marsh by the standards shown as pH 6.5-8.5,

COD less than 5 mg/I, SS less than 15 mg/I, SS less than 15 mg/I, and DO more

than 5 mg/I. Water quality of the marsh is characterized as follows:

_a. The COD value becomes higher as depth increases. Increment of COD

is much more than that of BOD concentration. Also, increment of the

COD value is related to the amount of nitrogen and phosphorus; on

the other side, DO concentration is less as depth increases.

b_. SS concentration is highest in the deep areas, and suspended sludge

exists at the bottom.

154
K,. Concentrations of both nitrogen and phosphorus become higher with

depth and the concentration of the bottom layer is 50 times as much

as surface layer.

•. DO shows more than 5 mg/I below 1 m from the surface. DO decreases

as depth increases, indicating almost a nonoxygen state at the

bottom.

j. C1 is high because of brackish marsh.

Analysis of Bottom Sediments

The analysis of the bottom sediment used dredged muddy water as shown in

Table 1. The bottom sediment is black colored and viscous and has extraordinary rancidity. It is much polluted; volatile solids ratio exceeded

20 percent; oxidation reduction potential (ORP) figure showed minus 580 mV; DO

was not detected; and amounts of N and P were a lot. Results of bacteria

tests showed that a number of coliform groups were contained in the sediments,

far more than general kinds of bacteria. It is foreseen to affect fishes and

shells.

TABLE 1. ANALYSIS OF THE BOTTOM SEDIMENTS

Item Unit Analytic Value Item Unit Analytic Value

Appearance black Cd mg/kgDS 0.3

Odor rot Pb mg/kgDS 21.7

SS 8.92 As mg/kgDS 10.8

VSS 1.86 Cu mg/kgDS 82.3

VSS/SS 20.8 T-Cr mg/kgDS ND

pH 8.8 Zn mg/kgDS 310

DO mg/1 ND T-Hg mg/kgDS 0.09

ORP mV -580 PCB mg/kgDS ND

N mg/kgDS 5,340 Fe mg/kgDS 43,000

C mg/kgDS 2,760 Bacteria /cc 810,000

Si mg/kgDS 12,500

S mg/kgDS 209,000

155
Bottom Sediments-Volume

It is estimated that approximately 35,000 m3 of the bottom sediments

deposited on the bottom of the marsh.

Pollution Mechanism of Marsh Furukawa

Domestic waste water from Rikuzen Takada City has caused pollution of

the marsh. Waterweeds and microorganism grown in the marsh died in due time,

depositing on the bottom of marsh and finally becoming putrefactive to affect

the sediments' quality worse. Moreover, heavy seawater that flows into the

marsh stays at the bottom, obstructing water circulation in the marsh. It was

proved that the bottom water that stayed just above the bottom sediments was

much more polluted than surface water; that is, the condition of the polluted

bottom water coincided with degree of the polluted bottom sediments.

TESTING FACILITY

Testing Eguipment

Transparent acrylic water tanks with effective capacity of 30 2 were

utilized during the experiments. The bottom of the tanks were "Via shaped

(90 deg) for smoothing circulation of sludge water and observing sedimentation

of sludge. For effective testing, six water tanks were installed; each tank

was filled with a different combination of the bottom sediments and activated

sludge for acclimation. For observation and recording, the results of test

progress, DO and ORP meters were installed on the tanks.

Since an appropriate mixture ratio between the bottom sediments and

activated sludge was not known before tests began. five water tanks (from

No. 1 to No. 5), which give different mixture ratios, were prepared as shown

in Figure 3. After the simplified analysis of the test results at the site

was examined, several kinds of tests were carried out by using No. 2 water

tank (67 percent of bottom sediments plus 33 percent of activated sludge) to

compare with the test results of the No. 1 water tank (100 percent of bottom

sediments).

measuring tank --------- (1) CDO) '-15ac/ i - Recorder (2) (OfF) ±50kV

(3) 9

sludge tank Sediments task Airlinow meterlAriemo r AtVi low meter Airfline uster: Airflowr moter Airlowe mater

Wtrtank Water tean Water teank1 water tank Water tank Waetr tank

REsludgeEC ISedimatsE =E1E =201 i3KI = 4Z Z5E

1111 Sedmmm 34ments 12/ d 301 Sediments 202: Sediments 25 2: Sediments 27 2: Sediments 29 2 :Acivaed-301Sediments :Activated 102 ActI eted 5j9- Activated 32 Activated 119

02)C2001) ( s ludge ...do* . sludge sludge sludge

Aeration eaulmaent

Figure 3. Testing equipment

156
Test Operations

The operation method of this test was done by the batch-type operation

in which aeration and sedimentation continuously operated for an 8-hr period;

each period was repeated three times; that is, 24 hr were operated

continuously.

These operations were automatically controlled by the previously programned sequencer. changes in concentration of DO, ORP, and pH were recorded

by the instrument in each tank, and functions of the bio-reactors were analyzed. Figure 4 indicates the operation time chart.

Test term Sedimentation+Aeratien cyle Aeration

tim time inteneity

A 1987/10/28-1/28 5.0+ 3.0 S /c x 3c/ d 200N/h

B 1987/1228-1988/1/4 4.0+ 4.0 - IcX3c/ d 201f/h

C 1988/1/ 5-2/05 3.0+ 5.0 -8 Cx3cj/ d 5f£/h

Aerati Sedimentatlon m time

Time 1 1 2 4 5 6 7 8

A

B

C

I I/

Figure 4. Time chart of operation

TEST RESULTS

Test results for sludge concentration and water quality are described

below.

Sludge Concentration

It was expected that the sludge concentration in the testing tanks would

be reduced by the biological treatment. The sludge concentration in the No. I

water tank (100 percent of bottom sediments), however, was maintained in a

stabilized state as shown in Table 2, whereas in the No. 2 water tank (67 percent of bottom sediments plus 33 percent of activated sludge) the sludge concentration was largely reduced as shown in Table 3.

Figure 5 indicates the changes of SS and volatile solids (VSS) in No. 1

and No. 2 water tanks and SS in supernatant and treated water in the tanks.

157
TABLE 2. CHANGES OF SLUDGE CONCENTRATION IN NO. 1 WATER TANK

(SEDIMENTS 100 PERCENT)

Days Starting Day 30 Days 75 Days

Item

MLSS mg/2 75,000 100% 56,100 74.8% 73,800 97.3%

VSS mg/I 14,900 100% 18,900 126.8% 14,800 99.3%

SS-VSS mg/1 60,100 100% 37,200 61.8% 59,000 98.1%

TABLE 3. CHANGES OF SLUDGE CONCENTRATION IN NO. 2 WATER TANK

(SEDIMENTS 67 PERCENT PLUS ACTIVATED SLUDGE 33 PERCENT)

Days Starting Day 30 Days 75 Days

Item

MLSS mg/I 54,800 100% 36,400 66.4% 22,200 40.5%

VSS mg/I 12,400 100% 14,600 117.7% 5,850 47.2%

SS-VSS mg/1 42,400 100% 21,800 51.4% 16,350 38.6%

The above figure shows the changes of sludge concentration in the No. 1

water tank (bottom sediments only) and the No. 2 water tank (sediments plus

activated sludge). The sludge concentration in the No. 2 water tank was

reduced as testing time passed. Thus, the reduction by using the activated

sludge was resulted effectively.

Water Ouality Tests

Changes in water quality are shown in Tables 4 and 5.

Consideration of Sludge Concentration and Water Quality Tests

By these tests, it was found that there were large differences in the

changes of sludge concentration between No. 1 and No. 2 water tanks. It also

was proved that the use of the activated sludge process for acclimation

effectively resulted in reducing the amount of the bottom sludge.

It took 75 days for the tests to get the results of the nitrification

observed which the activated sludge added to the bottom sediments for acclimation. It also took 100 days for the test to get the expected water quality

with performing de-nitrogen treatment by reducing airflow of aeration.

According to the activated sludge process, it takes two to three weeks to

reach reaction of nitrification and de-nitrate by batch-type treatment, while

a longer term is necessary for the acclimation to treat the bottom sediments

by biotechnology. Basically, nitrification and de-nitrate reaction can be

controlled with a similar process as a biological denitrification treatment.

Removal efficiency of phosphorus is better in the t- . and expected water

158
No. I water tank No. 2 water tank

(sediments) (sediments plus

activated sludge)

[(/IJ 301 20f +10f

00. 000

Mixing water SS -. 50. O'l

Mixing water VSS--.....0......... .......... hO. lOg0tSupernatant SS-- 5.000 -V1 i

Treated water VSS-O __,.__

Supernatant SS-A 1.000

Soo

100

I _ _ _ I "_- I I _

so

10/30 11/28 1/5 1/30 10/30 11/28 1/5 1/30 (d)

Figure 5. Changes of SS ar 'S in No. 1 and No. 2 Water Tanks and SS

in Supernatant *eated Water in the Tanks

quality is obtained by a sand filter process without coagulating treatment.

This de-phosphorus would be caused by the reaction of metallic salts contained

in the bottom sediments rather than by biological de-phosphorus treatment.

The test results did not show the large difference in the changes in

water quality in the No. 1 and No. 2 water tanks. The effect of the activated

sludge sued as a seeding sludge was not observed and was expected before the

test. A few days later, the rot odor from each testing water tank reduced and

remained a slight odor, same as normal activated sludge.

Changes in Sludge CoMosition

Changes in the composition of the bottom sediments by the biological

treatment in No. 2 tank were analyzed for 30 and 75 days.

159
TABLE 4. TREATED WATER QUALITY IN NO. 1 WATER TANK (SEDIMUTS 100 PERCENT)

[mg/li

Tes Days Starting Day 30..Ay. 75 Days

Item Mixing Water Supernatant Treated Water Treated Water Treated Water

pH 8.0 5.8 6.1 6.5 6.8

BOD5 2,220 96 4.0 8 1.2

COD Mn 5,510 91 46.9 21.8 5.2

NH-N 66 8.4 60.4 10.8 0.2

N02-N ND ND 0.1 2.5 ND

N03-N ND ND 0.5 22.3 0.9

KJ-N 222 72.5 70.6 46.7 2.1

T-N 222 72.5 70.7 71.5 3.0

P04-P 4.1 0.02 0.04 0.004 0.004

T-P 138 4.0 0.6 0.3 0.06

TABLE 5. TREATED WATER QUALITY IN NO. 2 WATER TANK (SEDIMENTS 67 PERCENT PLUS

ACTIVATED SLUDGE 33 PERCENT)

[mg/l]

Test Days Starting Day 30 Days 75 Days 100 Days

Item Mixing Water Supernatant Treated Water Treated Water Treated Water

pH 7.3 6.2 5.8 5.4 6.9

BOD5 2,100 105 3.0 5 1.0

COD Mn 5,800 130 35.5 21.8 6.2

NH-N 15 10.1 51.6 19.2 0.3

N02-N ND ND 0.6 41.3 ND

N03-N ND ND 0.6 41.3 1.2

KJ-N 250 98.2 60.4 5.2 0.7

T-N 250 98.2 61.0 46.6 1.9

P04-P 6 0.02 0.006 0.004 0.004

T-P 102 3.7 0.6 0.2 0.06

160
Reduction Tendency of the Bottom Sediments Volume

Reduction tendency of the bottom sediments volume by test is shown in

Table 6. The volume of the bottom sediments (1,644 g) in No. 2 tank was

reduced to 40.5 percent, or 666 g.

TABLE 6. REDUCING TENDENCY OF THE BOTTOM SEDIMENTS

(NO. 2 WATER TANK)

Item Unit Startino Day 30 Days 75 Days

MLSS mg/I 54,800 35,400 22,200

"g 1,644 1,092 600

"% 1 100 66.2 40.5

Changes in the Composition of the Bottom Sediments

The results of the tests showed that the reduced volume of the bottom

sediments brought some different changes indicating increase or decrease of

the composition ratio (mg/kg DS). It seemed to be the tendency for some

changes to occur while the biological treatment was performed. Changes in the

composition of the bottom sediments are shown in Table 7.

TABLE 7. CHANGES IN COMPOSITION OF THE BOTTOM SEDIMENTS

(NO. 2 WATER TANK)

Item Unit Starting Day 30 Days 75 Days

C mg/kgDS 60,000 71,000 89,000

N mg/kgDS 4,630 5,190 6,920

P mg/kgDS 2,250 3,240 5,360

S mg/kgDS 10,200 4,760 2,100

Si mg/kgDS 172,000 164,000 149,000

Fe mg/kgDS 38.600 53,900 94,200

In regard to the composition of which volume did not change by the biological treatments, the ratio of this composition (mg/kg DS) in the bottom

sediments tends to increase with reduction of the sediments. Also, with

respect to the composition of which the volume reduction is larger than the

volume reduction of bottom sediments by the biological treatments, the ratio

of this composition (mg/kg DS) tends to decrease.

Some compositions (p, Fe) in the sludge were unchanged in volume by the

reducing effect on sludge, whereas other compositions (C, N) decreased in

volume, while the concentrations (mg/kg DS) of these composition increased by

the biological treatment. The volume of compositions (Si, S) in the sludge

decreased, in parallel with the decrease of concentration.

161
Changes in the volume of each sediment by the biological treatment,

which was contained in the sludge of the No. 2 tank (30 1), were calculated

from analyzed values (mg/kg DS) on Table 7 and from the volume (g) of the

composition in reduced bottom sediments. The volume of composition for

soluble and volatile substances was excluded.

Changes in the composition volume (g) and its ratio (percent) are shown

in Tables 8 and 9.

TABLE 8. CHANGES IN COMPOSITION VOLUME OF THE BOTTOM

SEDIMENTS (G) (NO. 2 WATER TANK)

Item UUnit Starting Day 30 Days 75 Day

C g 98.64 77.53 58.27

N g 7.61 5.67 4.61

P g 3.69 3.54 3.57

S g 16.77 5.20 1.40

Si g 282.6 179.1 99.2

Fe 1 63.46 58.85 62.7

TABLE 9. CHANGES IN COMPOSITION RATIO OF THE BOTTOM

SEDIMENTS (PERCENT) (NO. 2 WATER TANK)

Item Unit Starting Day 30 Days 75 Days

C % 100.0 -21.1 -39.3

N % 100.0 -25.5 -39.4

P % 100.0 - 4.4 - 3.6

S % 100.0 -68.9 -91.6

Si % 100.0 -36.7 -64.8

Fe % 1 100.0 - 8.3 - 1.2

Each change in the composition of the improved bottom sediments in No. 2

tank treated by the biological treatment is as follows:

A. Si Reduction tendency is similar to the bottom sediments.

h. P,Fe Reduction has not occurred.

c. CN . Reduction is less than the reduction of the bottom sediments

volume.

d. S . . . Reduction is more than the reduction of the bottom sediments

volume.

162
Figure 6 shows the quant-itative changes (g) of the composition in

sludge, and Figure 7 shows the changes (percent) of the composition in sludge

in No. 2 water tank.

j. Test date 1987/10-88/02

E. Test tank No. 2 water tank

m. Sediments 201+Activated sludge 101

[gz] [J

Ss -- 10. 000oo 100

vss --O 5.000 90

SS-VSS --4 90

S 17'8 80 

C -0 1.000 -

N -4 500 IS5 70

-. .... .- 60 C. N

S -0 100 S i 50 VSS

-o 50 S 5 S S--50 __C 40 - •. SS

1 0 LN30 S i

20

10 1 S

P 0

0 30 75 ( d) 0 30 75( d)

Figure 6. Changes in composition Figure 7. Changes in composition

of the improved bottom of the improved bottom

sediments (g) sediments (percent)

In general, the amount of organic matters which consist of the sludge is

changeable by the biological treatment. In this experiment, however, it was

observed that each composition indicates a different pattern of change to the

biological treatment.

Release Test

The release tests were conducted for both the bottom sediments and the

improved one and studied the state of nutrient salts and the effect on water

quality.

163
Test Method

Predetermined volumes of the bottom sediments and the improved bottom

sediments were put into test tubes (ID 20 cm), and the marsh water added to

both tubes. the tubes were sealed with paraffin to prevent dissolved oxygen

loss. The tubes were stirred gently not to cause diffusion of sludge, thus

keeping predetermined temperature to observe conditions of water quality.

Test Substance

Bottom sediments, improved bottom sediments, and marsh water of marsh

Furukawa were the basic ingredients of the test.

Test Equipment Outline

The drawing below is an outline of the equipment.

3 Agi tator 0

Marsh water Marsh water 70cm

Sediments Improved sediments 30cm

Changes in Water Quality in the Release Test

Tables 10 and 11 that follow show the changes resulting from release

tests on bottom sediments and improved bottom sediments.

Figure 7 shows the results of release tests from the bottom sediments

and the improved bottom sediments. The figure also indicates test results

under the de-oxygen state. There are obvious differences in the release

characteristics (release rate and quantity) between two kinds of the bottom

sediments. Especially total nitrogen has a remarkable difference; that is,

total nitrogen in the improved sediments shows a decreasing tendency against

releasing.

Figures 8 and 9 show the release quantity and rate of the bottom sediments and the improved bottom sediments.

The release test result for COD is shown in Figure 10. This figure

resulted from the release tests under the de-oxygen state. Changes in the COD

value tended to lag behind the BOD value. Co-relations were observed between

COD and BOD values.

164
TABLE 10. CHANGES IN WATER QUALITY IN TANK BY RELEASE

TEST (BOTTOM SEDIMENTS)

_ __ __IL]

Days 1 3 5 10 20 30

Item

BODS 1.2 1.9 2.0 1.8 1.5 2.0

CODN 3.5 4.8 5.0 6.2 7.9 8.1

Sulfide 0.8 1.1 1.5 1.8 3.0 4.6

KJ-N 0.32 0.58 0.99 1.56 2.54 4.5

NH4,-N 0.02 0.77 0.85 0.93 2.22 4.54

N02-N 0.028 ND ND ND ND ND

NO3 -N 0.8 ND ND ND ND ND

T-N 1.17 1.35 1.84 2.50 4.76 10.46

P0-P 0.004 0.032 0.088 0.098 0.140 0.185

T-P 0.012 0.034 0.125 0.28 0.53 2.16

DO 5.6 1.2 0.5 0.4 0.4 0.4

TABLE 11. CHANGES IN WATER QUALITY IN TANK BY RELEASE TEST

(IMPROVED BOTTOM SEDIMENTS)

[____g/.J]

Days 1 3 5 10 20 30

Item

BOD5 1.2 1.2 1.0 0.9 0.8 0.6

CODj 3.5 4.6 3.6 3.2 3.1 3.0

Sulfide 0.8 ND ND ND ND ND

K -N 0.32 0.38 0.20 0.12 0.18 0.58

NH4-N 0.02 0.12 0.10 0.12 0.02 0.06

N02-N 0.028 ND ND ND ND ND

N03 -N 0.8 0.57 0.42 0.20 0.20 0.21

T-N 1.17 0.96 0.62 0.32 0.38 0.77

P04-P 0.004 0.004 0.004 0.006 0.008 0.010

T-P 0.012 0.030 0.025 0.028 0.024 0.022

DO 5.6 1.8 0.8 1.0 0.8 0.8

165
(mg/1] Sediments Improved sediments

10

SP

HOD -0 K ~ 4 -. 4-- biCOD -A j I I4LŽ

Sul tide-U

N02-N-4

0. 1 4

T0-P--O

0. 01

DON -AU

0.066
Release quantity r- mg/id

Sediments (tug/id] Sediments Improved sediments

-- A 7.00o 00- - - i - -

6.500

Improved sediments 6. 000- *

---A ~ ~~5. 500 , , , i

5. 000

4.500 i i

4.000 c o .• ,

3. 500I

3. 000

2. 500

r 2. 000

1. 500 / :!

1. 000

Improved effect Soo --. ,.

r = release i I"0Aquantity - -

-104.3 % -1.0 00

R= release Release rate R=uMg/id/d

rate

-104.5 Yo [mg/id d ] Sediments Improved sediments

250

225 200 .

275 •-s -- ---- - -

10

too i

R 75 ! '

..50 1 Q

-75

-100

1 3 5 10 20 30 (d) 1 3 5 10 20 30 (d)

Figure 8. Release test results of nitrogen from the bottom sediments and

the improved bottom sediments

167
Sediments Release quantity r=--mg/n

-A [mg/id] Sediments Improved sediments

Improved sediments 2.0000

1.900

1.800

1. Soo ! i 1. 500

I. too

1.o00

900

800

700

Improved effect 500 i

400 - -

300 ' A:;-'-

r= release 200 i

quantity 100 -

R=release - , _0__

rate

-99. 5% Release rate R~mg/u?/ d

(aig/id d]I Sediments Improved sediments

200

175. . " . '

175

-150

release_-_0 a 

rate

-25

-75 - - - - - -- - .- . - -

-100

15 35 102030 d13 5 102030(d

Figure 9. Release test results of phosphorus from the bottom sediments

and the improved bottom sediments

168
Sediments Release quantity r- m91n

COD--A Sediments Improved sediments

BOD--O 00oo

6.500

Improved sediments 5.500 -.. -4.__ 

" ° I i I I I I I i i 5.000

COD -- A 4. 50 -i - h - - - - i

B0D -- 0 4. 3.5s00 000 , ' : '

3.000 I

2.500 I - i I I j i

2.000 - - -

.00 [ I . i'! I i I i I i

Improved effect 1.500 117

BOD - release 500 i

quantity tY . ... t

-175% X 1 W..J'O.u

COD -release -1. o 0

quantity

-113 X Release rate R--mg/nd/d

BOD - reIease Sediments Improved sediments

rate

-175% 250 _

225 - _ ! '_ ' !

COD - release 200

ra te 15'

ISO

-113 Ya% 

Si si I

• ,! I t .......J....,.

10 J!

-ion ~,- . - ..

th -iprve boto sed'1iments- I

-50

-75 " "

-too A .i ! I 

1 3 5 10 20 30( d 1 3 5 10 20 30( d)

Figure 10. Release test results of COD from the bottom sediments and

the improved bottom sediments

169
Gas Generation Test

The gas generation test was carried out to study sludge characteristics

for the bottom sediments and the improved bottom sediment. The 100 g of the

bottom sediments picked up from the marsh and the same amount of the improved

bottom sediments from the No. 2 water tank were put separately into two flasks

(capacity 2 1). The 900 ml of distilled water was added into each flask, and

the flasks were quickly plugged by rubber plugs. Then the test equipment was

arranged as shown in Figure 11.

Pinch cock

Gas collecting bag

Constant-temp. water bath

Figure 11. Gas generation test equipment

When the temperature in the flasks reached the constant temperature,

after keeping it constant one hour, the pinch cock was opened to send nitrogen

gas to the flasks at the speed of 1 I/min for 10 min, and generated gas was

gathered in the collecting bag attached to the end of the pipe to analyze it

promptly.

The test result is shown in Table 12. The bottom sediments which were

treated by the biological treatment restrained generation of rot odor.

TABLE 12. GAS GENERATION RATE

Improved

Item Bottom Sediments Bottom Sediments

Ammonia NH3-N 105 16

Sulfide HS 280 ND

Methane CH 2,100 8

CONCLUSIONS

It was recognized that there was possibility for the organically

polluted bottom sediments to be improved by use of the bio-reactor. Test

results showed that the improved bottom sediments might restrain the generation of COD, nitrogen, and phosphorus that caused eutrophication. The test

results would apply to better effect the restoration of water quality and

170
ecosystem. The summary below includes the improved sediments, reduction of

pollution, treatment of spillwater, and rot odor in the experiments.

Imvroved Bottom Sediments

A. Improved sediments treated by the biological treatment have a color

of light brown and no rot odor.

). With respect to reduction of the polluted bottom sediments, addition

of the activated sludge and acclimation condition should be considered as well as retention time and aeration intensity.

c. Volatile solids ratio (VSS/SS) of the improved bottom sediments

increased in comparison with the bottom sediments.

d. ORP of the improved bottom sediments is between 450 and 520 mV.

e. Nitrogen causes inorganic feature, nitrification, and de-nitrate

reaction.

f. Phosphorus is stabilized by metals, and oxidation reaction occurred

in the bottom sediments; the release of phosphorus into the water is

restrained.

g. Improved bottom sediments retain a large amount of oxygen, which is

generated by oxidation of metal substances (iron, etc.) in the sediments and will be useful for the improvement of the bottom sediments

condition.

h. Improved bottom sediments contain bacteria (1,050 /cc) and coliform

groups (230 groups /cc) which restrain malignant bacteria.

Volume Reduction of the Bottom Sediments

a. Test result in which the activated sludge was added shows the reduction effect of the volume of the polluted bottom sediments.

b. Test result in which the activated sludge was not added observed no

reduction effect of the volume.

c. Reduction ratio of the bottom sediments in No.2 water tank was

33 percent after 30 days and 58 percent after 75 days.

d. Reduction rate in the No. 2 water tank was from 0.7 to 1.0

SS percent/d.

et. Reduction rate in the No. 2 water tank was from 600 to

400 SS mg/A/d.

•. Reduction tendency of the bottom sediments in No. 2 water tank was

observed in volatile solids (VSS).

g. Reduction would be effected by the quality of the bottom sediments,

retention time, aeration intensity, and characteristics and amount

of the activated sludge applied.

171
A. The smell or rot odor in the bottom sediments was like an addled

egg.

k. Rot odor caused in each testing water tank vanished in a few days

after the biological treatment.

•. Spillwater in each tank has no rot odor.

Soillwater Treatment

Since marsh Furukawa is classified as "B" type, it will be able to

improve the spillwater quality by treating COD, SS, T-N, and T-P contained in

it.

Prospects

It is considered that this technique should be applicable in cases of difficult dredged bottom sediments. These treatment techniques should be applied

to bottom sediments with high organic properties, while excluding the treatment of the bottom sediments contaminated by heavy metals.

The first experiments for the bottom sediments used bio-reactors for

treatment purposes, but there are many problems awaiting solution. Tests and

analyses must be repeated over and over again.

The problems are as follows:

A. Preparation of the guideline to improve bottom sediments by the

biological treatment.

k. In case of returning the improved bottom sediments into the marsh,

it should be analyzed with bioassay to determine the effects on the

ecosystem of the marsh.

•. Development of technology and equipment for returning the improved

bottom sediments back into the marsh by means of spraying it with

equipment.

d. Establishment of energy-saving technology for bio-reactor treatment.

CLOSURE

This report described the experimental results for the treatment of the

bottom sediments by using bio-reactors. It is planned that the middle scale

of the second experiment will be carried out in this year at Marsh Furukawa.

The treatment facility of the polluted bottom sediments has been oper~ating at the prawn farm in Okinawa, using the above technology. Also, in 1990,

the large scale demonstration experiments (capacity 25 m3

/d) had been

conducted based on the above technology in the biggest lake in Japan, and the

data have now been analyzed.

172
PCB VOLATILIZATION FROM DREDGED MATERIAL,

INDIANA HARBOR, INDIANA

Jay A. Semmler

U.S. Army Engineer District, Chicago

and

James M. Brannon

U.S. Army Engineer Waterways Experiment Station

ABSTRACT

This paper summarizes the theory and application

of a model to predict the mass loss of polychlorinated

biphenyls (PCBs) from dredged material through volatilization. A comparison to other contaminant pathways is presented for both in-lake and upland

disposal.

BACKGROUND

Contaminated sediments placed in a confined disposal facility (CDF)

provide the potential for volatiL irganic chemicals (VOCs) to be released

through volatilization. Theoretical models have been developed to describe

the physical and chemical processes involved in transferring the VOC from the

solid or liquid phase to the air (Thibodeaux 1989). To date, PCBs have been

the VOC of concern; however, the theory presented is applicable to other VOCs

including polycyclic aromatic hydrocarbons (PAHs). The documentation provided

is not sufficient to fully understand the development of the models described

in this paper. The user should refer to the original reports for complete

understanding of model development and limitations.

INTRODUCTION

Volatilization is the process whereby a compound passes into the air

from a solid or liquid surface. The degree of volatilization can be generally

related to Henry's constant of the compound: a compound with a high Henry's

constant has a higher volatilization potential than one with a low Henry's

constant.

The model presented in this note provides an estimate of the mass of

PCBs lost from an in-lake and an upland CDF. PCB was the only compound considered because of its regulatory significance and to simplify development of

the models. It is anticipated that other semivolatile and volatile compounds

such as PAHs will be modeled in the future for sediments contaminated with

these substances.

Chemical equilibrium principles are used in this note to determine the

transfer of the VOCs between various phases. In the case of VOCs associated

with sediment, three phases of matter are involved. The first phase includes

the solid particles which constitute the sediment and have both organic matter

and mineral matter comprising the particles. The two other primary phases

173
include air and water. With respect to dredging, VOCs can enter the air from

either the water or sediment surfaces. for volatilization to occur from the

water surface, the VOC must first desorb from the suspended solids phase and

diffuse through the water before emitted into the air.

MODEL PURPOSE

PCB volatilization models developed by Thibodeaux (1987) were adopted by

the Chicago District to local conditions as part of the preparation of the

Draft Environmental Impact Statement (DEIS) for Indiana Harbor and Canal Maintenance Dredging and Disposal Activities, Lake County, Indiana. The models

estimate the mass flux of PCBs form a proposed CDF by volatilization from

dredged material. Two scenarios were considered: The first assumes that the

dredged materials are placed in an in-lake CDF, while the second assumes

placement in an upland CDF.

Volatilization is complicated and can involve a number of transfer pathways. In order to quantify volatilization of contaminants to air, the major

sources, pathways, and external parameters which affect the transfer must be

addresses. Lab and field verification of critical transfer coefficients are

lacking, and hence a complete quantification of PCB volatilization for all

activities associated with a dredging operation is impossible. Therefore, the

models were used as an indication of the relative significance of volatilization when compared to other loss pathways (such as leachate, seepage, plant,

and animal uptake) for various operational schemes. In this manner, potential

PCB mass flux for different placement options can be estimated, and viable

options can be evaluated against each other and the no action plan.

MODEL ASSUMPTIONS

Theoretical chemodynamic models for organic pollutants in dredged material have been developed to estimate potential emission rates of PCBs to the

air (Thibodeaux 1989). Although these models have not been verified experimentally for dredged material, studies of pesticide volatilization from soils,

VOC emissions during refinery waste landfarming, and VOC emissions from

hazardous waste lagoons indicate that theoretical chemodynamic models, when

properly formulated, provide realistic estimated of VOC volatilization (Thibodeaux and Hwang 1982; Thibodeaux and Becker 1982; Thibodeaux, Parker, and Heck

1984; Eklund, Nelson, and Wetherhold 1987). It should be noted that input to

the model is highly dependent on the physical aspects of the particular CDF,

the placement method, and the amount of time for a particular filling operation, as well as the lifetime of the CDF.

The equation used to calculate flux from exposed sediments describes

chemical movement in the unsaturated pore spaces near the exposed surface.

Sediments are initially in a semisaturated state, but surface layers soon will

approximate the unsaturated-situation. This initial transient state is not

accounted state is not accounted for by the model. Also, wetting and drying

cycles generated by rainfall were not considered.

The major emission locales for a CDF and its inherent operations are

dredging and transporting, submerged sediments (ponded zone), exposed sediments void of vegetation, and sediments with vegetative cover.

174
Because of complexities involved and the lack of sufficient theory, this

evaluation considers only the submerged sediments and the exposed void of

vegetation locales as emission sources for PCB flux.

MODEL FORMULATION

Submerged Dredged Material

(Pond Volatilization) Algorithms

The pathway for volatilization in the case of submerged dredged material

involves desorption from the suspended solids phase, diffusion through the

water, and transport through the air-water interface. Assuming a constant

suspended solids concentration, the steady-state flux of an organic chemical

through the air-water interface is given by the following equation:*

r•- 1(d + 1/P32 - ZI

where

nA - flux of A through air-water interface, mg A/cm2 hr

A - organic chemical of interest

'KA - overall liquid-phase mass transfer coefficient, cm/hr

WA - concentration of A in the original bed sediment, mg/kg

Kd - sediment-water distribution coefficient for A, L/kg

P32 - concentration of suspended solids, kg/L

P** - hypothetical concentration in water for air side concentration

of A, mg/L

With respect to the overall liquid-phase mass transfer coefficient, when

the emission rate is liquid-phase resistance controlled, as it is for hydrophobic organics, 'KA depends on wind speed and molecular diffusivity of A in

water and can be estimated using the following equation (Lunney, Springer, and

Thibodeaux 1985):

1K2 - 19.6V2.'3T2/ 3 (2)

vX "A2

where

V. - wind speed, mph

DA2 - molecular diffusivity of A in water, cm2/sec

If the diffusivity of A in water is not known, it can be estimated using

the following equation (Thibodeaux 1979):

* Environmental Laboratory. 1988 (20 July). Information on the Volatilization of Organic Pollutants from Dredged Material, Memorandum, U.S. Army

Engineer Waterways Experiment Station, Vicksburg, MS.

175
DA2 - DB2(?ý/^) 0 (3)

where

DN2 - molecular diffusivity of B in water, cm2/sec

B - model organic chemical of known molecular diffusivity

MH - molecular weight of B

MA - molecular weight of A

The quantity WA/(Kd + 1/p32) is the dissolved concentration of A in the

pond water and can be thought of as the dissolved concentration of A at the

air-water interface. The difference between it and p* is the driving force

which cause the flux of A into the air.

The value of p** is derived from the existing concentration of A in

the air. This value is very small compared to the water concentration and

therefore, if assumed to be zero, would have little effect on the driving

force. This conservative assumption maximizes volatilization.

Equilibrium partitioning uses the relative chemical solubilities of

hydrophobic organic compounds (like PCBs) in sediment and water to estimate

the concentrations of the compound in these two media at equilibrium. PCBs

are poorly soluble in water and have a high affinity for sediments, particularly those with much organic matter. The ratio of PCB concentrations in

sediment and water at equilibrium is referred to as K

1 d This partitioning

coefficient (Kd) can be calculated from chemical properties of the contaminant

(PCB) and information about the total organic content (TOC) of the sediment or

through a number of laboratory procedures. The Kd for PCBs in the Indiana

Harbor sediments was determined through sequential batch leach testing and

column leach testing by the U.S. Army Engineer Waterways Experiment Station

(WES) as 256,000 L/kg (Environmental Laboratory 1987).

Equation 1 is applicable as long as the suspended solids concentration

is not reduced to identically zero. In a CDF, the suspended solids concentration usually decreases when filling operations are discontinued, but never

goes to zero because of resuspension. When the suspended solids concentration

is very low and cannot be reliably estimates, flux may be better estimated

using the following equation (Thibodeaux 1979):

NA - K'(pA - pA) (4)

where

pA2 - bulk liquid dissolved concentration of A, g/cm3

p* - hypothetical concentration in water for air side concentration of

A, g/cm3

ExRosed Dredged Material Algorithms

The volatilization pathway for exposed dredged material incorporates a

number of steps. Although sediments are placed in a semisaturated state,

176
water and VOCs become quickly depleted from the surface layer, and continuing

losses come from the pore spaces within the dredged material beneath the

surface. At this point, VOC emission is dredged material-side vapor phase

diffusion controlled. The emission pathway involves desorption from particle

surfaces into a water film surrounding the particles, diffusion through the

water film, desorption from the water film into the pore gas, and diffusion

through the pore gas prior to emerging into the atmosphere. This last step is

apparently the limiting step in soil systems (Dupont 1986), and this condition

is thought to apply to the top layers of dredged material in a CDF (Thibodeaux

1989). Ficks second law, with an effective diffusivity that accounts for

tortuosity of the diffusion path and other factors that affect diffusion, is

an appropriate mathematical model. Because of the depth of the dredged material and the relatively flat surface, a semi-infinite solution to Ficks second

law can be applied without serious error. (The semi-infinite solution is

conservative; that is, flux is maximized). The instantaneous flux is given by

/12

DA3 1 = I[ H - (5)

nA^ = t j PM±J

where

nAt - instantaneous flux of A through dredged material-air interface

at time t, mg A/cm2/sec

DA3 - effective diffusivity, cm2 /sec

E- air-filled porosity, dimensionless

P3 - bulk density of dredged material, kg/L

H - Henry's law constant, dimensionless

t - time since initial exposure, sec

PAli - background concentration in air at dredged material surface,

usually assumed to be zero, mg/cm3

The average flux over a given time t is given by

t

JA= dt (6)

ft

It can be shown that

YA= 2 nA,t (7)

Equation 7 is an idealized diffusion transport model that describes

chemical movement in the unsaturated pore spaces near the surface of exposed

177
dredged material. It does not account for the development of cracks as the

dredged material dewaters by evaporative drying.

Effective diffusivity is a constant diffusion coefficient that characterized the movement of chemical A as a vapor within the porous solid. It is

one parameter for which there is no information available. To calculate the

flux, it is therefore necessary to estimate DA3 . As an approximation,

tortuosity can be accounted for using the equation below (Thibodeaux 1987):

DA3 = D DA[E°13] EZ (8)

where

DA, - molecular diffusivity of chemical A in air, cm2/sec

E - total porosity, dimensionless

Henry's law constant (H) applies for dilute solutions of chemicals in

air and water. It is an equilibrium partition coefficient for chemical A

between the air and water phase. Henry's law constant can be estimated using

the equation below (Dilling 1977):

H = 16.04 [-T] (9) [Tp•J

where

P- vapor pressure of A as pure solute, mm Hg

T - temperature, deg K

p1 - solubility of A in pure water, mg/L

The background concentration PAli in air has an analogous meaning to

PA2 and is also assumed to be zero. This conservative assumption maximizes

volatilization.

RESULTS

Table 1 shows the maximum annual simulated PCB loss for three contaminant transfer pathways. The data presented in the table represent loss of PCB

occurring in the first year after disposal of the highest contaminated sediment. Table 2 shown the input parameters used to estimate PCB volatile

losses. Estimated PCB volatilization losses from an upland cdf were considerably higher than estimated losses from an in-lake CDF, because over the filling life of the CDF, the exposed surface area in an in-lake CDF is much lower

than for an upland CDF. During most of the filling, the dredged material is

placed and remains submerged.

178
TABLE 1. ESTIMATED (WORST CASE) ANNUAL PCB LOSS (LB)

In-Lake CDF Upland CDF

Seepage* Leachate** Volatile Seepage* Leachate** Volatile

0.0001 0.001 2 0.0001 0.001 8

* Mass of PCB loss estimated through dike wall or CDF bottom.

** Mass of PCB loss estimated to be collected and treated as leachate.

INTERPRETATION OF RESULTS

The results indicate that volatilization of VOCs is a significant contaminant transfer pathway. Also, PCB mass flux is less when the sediments are

maintained in a submerged state because of the hydrophobic nature of PCBs.

The flux is highly dependent on two factors--the exposure time of the sediments and the surface area of the sediments. The exposure time for submerged

sediments encompasses the entire time a pond is in contact with PCB-contaminated sediments. However, the rate of volatilization is directly related to

the concentration of PCBs varies over time with the highest -ate during an

active filling operation. The surface area is that area of the pond which is

in direct contact with the air and is dependent on the volume of dredged material being placed and the volume of material already placed within the CDF.

The exposure time for exposed sediments encompasses the time in which

unsaturated sediments are in direct contact with the air, while the surface

area is that area which is in direct contact at any given time.

Laboratory analysis has recently been completed by WES on New Bedford

Harbor sediments in order to determine the volatile emission rates of PCBs

from freshly placed drying sediments.* This experiment was conducted under

laminar conditions, excluding the effects of wind. Laminar flow represents an

overall simplified condition but does support the analyses presented in this

note.

In summary, the approach taken in model formulation was conservative in

nature in hat it simulated a worst-case scenario. For instance, the exposed

sediments were assumed to be completely void of vegetation throughout the life

of the CDF. However, from past experience a vegetative cover will form over

the exposed sediments over time. No quantitative theory predicts the effects

of vegetation on flux, but it is anticipated that the vegetation cover should

reduce the flux rate. Also, the surface area of exposed sediments was simulated as a layer covering the entire cell (only for upland CDFs). Realistically, the deposited sediments would flow outward, but probably not far enough

to cover the entire cell of an upland CDF. Finally, the suspended and dissolved solids concentrations in the ponded areas were based on conservative

* Environmental Laboratory. 1989 (April). "Laboratory Assessment of Volatilization from New Bedford Harbor Sediment," Memorandum, U.S. Army Engineer

Watorways Experiment Station, Vicksburg, MS.

179
TABLE 2. INPUT PARAMETERS FOR PCB VOLATILIZATION MODELS

Parameter Description Value

Assumed Values

Kd Sediment-water distribution coefficient 256,000 L/kg

WA PCB sediment concentration

1. Backlog sediment (zone 1) 38 mg/kg

2. Backlog sediment (zone 2) 6 mg/kg

3. Long-term maintenance sediment 2 mg/kg

P32 Suspended solids concentration

1. Within 100-ft radius of disposal 100 mg/L

2. Away from disposal area 10-50 mg/L

PA Dissolved PCB concentration 5-60 mg/L

MA Composite molecular weight of PCB 300

PB Bulk density of sediment 1.2 mg/kg

DA Molecular diffusivity of PCB in water 4.2-06 cm2/sec

DAI Molecular diffusivity of PCB in air 0.049 cm2/sec

AP Vapor pressure of PCB are pure solute 4.94-04 mm Hg*

pA Solubility of PCB in pure water 0.054 mg/L*

E Total porosity 0.70

E, Air-filled porosity 0.30

Vx Mean wind velocity 8-12 mph

Calculated Values

'K• Mean overall liquid phase mass transfer 0.78 cm/hr

coefficient

DA3 Mean effective diffusitity 1.63-03 cm2 /sec

H Mean Henry's law constant 0.156

* Value used for Aroclor 1248.

180
estimates. For the reasons stated above, the actual PCB mass flux from a CDF

could be substantially lower than what is predicted by the model simulation.

CONCLUSIONS

Theoretical models must be tested against and adjusted to both laboratory and field data prior to their acceptance and widespread use as predictive

tools. Preliminary model calculations can be made for the submerged sediment

locale and the exposed sediment locale void of vegetation. However, some

aspects are based on very simple equations, and further development is needed.

Laboratory and field testing must be performed to build a higher degree of

confidence in the predictive capability of the PCB volatilization models. A

substantial amount of work in laboratory/field testing and verification needs

to be completed before any conclusive results can be made on PCB flux simulation from an active CDF.

REFERENCES

Dilling, W. L. 1977. "Interphase Transfer Processes II; Evaporation Rates of

Chloromethanes, Ethanes, Ethylene Propanes, and Propylenes from Dilute Aqueous

Solutions," Environmental Science and Technology, Vol 11, No. 4, pp 405-409.

Dupont, R. R. 1986. "Evaluation of Air Emission Release Rate Model Prediction of Hazardous Organics from Land Treatment Facilities," Environmental

Progress, Vol 5, No. e, p 197.

Eklund, B. M., Nelson, T. P., and Wetherhold, R. B. 1987. "Field Assessment

of Air emissions and their Control at a Refinery Land Treatment Facility:

Vol I," EPA/600/2-87/086a. Hazardous Waste Engineering Research Laboratory,

Cincinnati, OH.

Environmental Laboratory. 1987. "Disposal Alternatives for PCB-Contaminated

Sediments from Indiana Harbor, Indiana," 2 Vol, U.S. Army Engineer Waterways

Experiment Station, Vicksburg, MS.

Lunney, P. D., Springer, C., and Thibodeaux, L. J. 1985. "Liquid-Phase Mass

Transfer Coefficients for Surface Impoundments," Environmental Progress,

Vol 109, No. 4, pp 203-211.

Thibodeaux, L. J. 1979. Chemodynamics, John Wiley, New York.

Thibodeaux, L. J. 1987. "Theoretical Framework for Development of Methods

for Predicting Volatile Emissions to Air from Dredged Material Disposal,"

U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Thibodeaux, L. J. 1989. "Theoretical Models for Evaluating Volatile Emissions to Air during Dredged Material Disposal with Applications to the New

Bedford Harbor Superfund Site," Miscellaneous Paper EL-89-3, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Thibodeaux, L. J., and Becker, B. 1982. "Chemical Transport Rates near the

Sediment in Wastewater Impoundments," Experimental Progress, Vol 1, No. 4,

p 296.

181
Thibodeaux, L. J., and Hwang, S. T. 1982. "Landfarming of Petroleum WasteModeling the Air Emission Problem," Environmental Progress, Vol 1, No. 1,

p 42.

Thibodeaux, L. J., Parker, D. G., and Heck, H. H. 1984. "Chemical Emissions

from Surface Impoundments," Environmental Progress, Vol 3, No. 2, pp 73-78.

182
SEA BLUE PLAN: A CASE STUDY ON PORT OF

AMAGASAKI-NISHINOMIYA-ASHIYA

Hideo Hamabata, Yusuke Suda

Japan Sediments Management Association

Hiroshi Sugimoto

Amagasaki Port Administrative Office

Hyogo Prefectural Government

ABSTRACT

A case study of the SEA BLUE PLAN was held in

the canal area of Amagasaki, Prot of AmagasakiNishinomiya-Ashiya. Recently, industrial factories

are retreating from the reclaimed area of the canal

area of Amagasaki leaving the land unused. Meanwhile,

citizens desires a pleasant environment in the waterfront area. In response to the request, the utilization of the waterfront for leisure and relaxation not

just transportation and industry was considered. We

proposed six measures for environmental improvement:

1. Dilution and diffusion by river water conveyance.

2. Dilution and diffusion by sea water conveyance.

3. Water purification by porous bed contact purification method. 4. Water purification by living

filter. 5. Dredging and sand-capping. 6. Retrieval

of floating garbage. By using these measures with

some creative ideas, the water and sediment quality in

the canal area will be improved and further, a pleasant coastal environment will be realized in Amagasaki

canal area.

BACKGROUND OF STARTING CASE STUDY

The Port of Amagasaki-Nishinomiya-Ashiya had been threatened by storm

surges and ocean waves caused by typhoons since the port is located at the

innermost part of the Osaka Bay. Under these circumstances, Amagasaki Lock

was built in 1955 because of typhoon Jane which struck in 1950. Since then,

the lock has been playing a very important role of protecting the citizens

from disasters and in harbor facility activities which support the industrial

city of Amagasaki.

On the other hand, the lock has shut off the seawater flows into the

Amagasaki canal area located in the inner side of the lock. The water and

seabed of the area became contaminated because of the wastewater from homes

and factories which flows into the area causing environmental problems to the

adjacent areas.

To solve this problem, dredging of the canal was started to purify the

water, but not enough was done to improve environmental contamination of the

183
surrounding areas. Some measures are still needed for environmental

improvement.

In adjacent areas of the canal area, a couple of projects have been commenced, such as the Phoenix Project and the coastal road construction work.

Amagasaki Lock also is under improvement and for completion in 1995. Besides

that, Amagasaki City is planning the redevelopment of the southern coastal

area of the city for the 21st century. Thus, steps to solve environmental

problems and promote development are on the discussion table.

For these reasons, the central government, Hyogo Prefecture, and

Aaagasaki City jointly conducted a survey to study the present state of the

environment, canal utilization, and surrounding areas. In this study, they

considered utilization methods, facilities, and project methods which fit the

characteristics of the area. This survey on the active use of the canal

waterways identified specific methods to make the area pleasant and appealing

for the citizens and the users of harbor facilities.

On the other hand, the government and Hyogo Prefecture jointly carried

out the Sea Blue Technology Survey on how to purify the canal water in respect

to technical methods, suitably for surrounding areas, facilities, and project

methods. A part of the study applied, and its result shall be reported in the

following pages.

PROCEDURE OF CASE STUDY

The survey for the Sea Blue Plan was carried out with the following procedure taking the existing major plan and related plans in the canal area into

consideration.

Comprehension of the Present

Situation of the Canal Area in Ouestion

By surveying the site or by perusing literature, the condition of the

natural environment such as marine phenomenon, quality of water and sediments.

and the social environment was confirmed. The relevant plans in action were

also reviewed by checking existing materials and data.

Organizing and Identifying

Problems of the Present Situation

The needs of the area in question need to be grasped by comparing them

with the reality of the present environment. Thus, the problems can be sorted

out and identified.

Reviewing of Basic Concert

Setting of the aim to be accomplished for environmental improvement and

its utilization consider the conformity with the existing major plan and

related plans. Then, the purification methods to apply to this plan will be

discussed.

The aim to be accomplished should be one which is easily understood by

the average citizen. Basically, the words used in the plan should appeal to

the five human senses in stages of touching, viewing, and so forth. In the

184
quantitative evaluation of purification results, of course, environmental

indices such as COD, SS, etc., are to be used; however, such technical terms

should be transplanted into simple daily words corresponding to the five

senses.

Reviewing of Basic Plan

In accordance with the basic concept. the detail of the facilities

including the layout will be presented. Furthermore, the budget for execution

and probable effect of the environmental improvement will be discussed.

Problems to be Settled

Before Imglementation

Sorting out and identifying problems were necessary for the accomplishment of the plan.

CASE STUDY ON PORT OF AMAGASAKI-NISHINOMIYA-ASHIYA

Comprehension of the Present

Situation of the Canal Area in Ouestion

Topography and History of

the City as an Industrial City

Amagasaki City of Hyogo Prefecture is located at the innermost end of

Osaka Bay, in the central part of Japan (Figure 1). Its area is approximately

50 km2 and the population is approximately 500,000. It is commercial and

industrial city. Its eastern border is shared with Osaka City, the second

biggest city of Japan. Amagasaki City, situated on the alluvium deposits

carried down by the river, has many lowlands and the highest part of the city

is merely 20 m above sea level. Land of 0 m above sea level occupies onethird of the city.

Amagasaki City made its start as a modern industrial city after the

Amagasaki Spinning Factory began operation in 1891. Following the RussoJapanese War (1904-05), glass and steel related factories started operation,

thus turning Amagasaki into a base for heavy-chemical industries. After World

War II, it became the center of the Hanshin Industrial Area during the rapid

economic growth of Japan which started around 1955. Because of this reason,

the coastal areas of the city became exclusively industrial areas. However,

current changes of industrial structure in Japan have made smokestack industries such as steel and chemicals retreat from the city. Thus, utilization of

former industrial land had to be discussed.

From around 1931, reclamation of the coastal areas was carried out in

step with the rapid growth as an industrial city at that time. In these

reclaimed areas in the southern part of the city. navigational canals run

vertically and horizontally (Figure 2).

Present Situation of Canal Area

These canals still operate for the transportation of materials, while

most of the waterways in Japan lost their essential functions. In addition,

185
AMAGASAKI

OSSAKA

BAY

10 km

Figure 1. Location of Amagasaki City

they function as disaster prevention facilities, i.e., as retarding basins to

store water during heavy rains.

The lock and gates were made at the border line between the canal and

the sea in order to maintain a fixed sea level for navigation and also to

prevent whole city from being flooded. Water in the canals stays still except

when the water level is lower than OP + 0.60 m or higher than 1.35 m. Consequently, there is no flow-in and flow-out of water most of the time. Partially because of the above fact and also to the flow-in of turbid water from

the upstream area of the river, contamination of the canal water is proceeding

rapidly.

186
HANSH IN LINE

Figure 2.N Canal ~ arai ~ zngs SOG 

KITAHORI

GAE KITANORI C.

d r MATSUSHIMA • ! DRAINA•GE ." PUMP STATION

Figure 2. Canal area in Amagasaki

Organizing and Identifying the

Problems of the Present Situation

New Forms of Utilization for the Canal Area

As described previously, industrial factories are retreating from the

reclaimed area of the canal leaving the land unused. Meanwhile, citizens

deiires a pleasant environmental in the waterfront areas. In response to the

request, the utilization of the waterfront for leisure and relaxation, not for

just transportation and industry, was considered. With this background,

reutilization of the Amagasaki canal area came to the table for discussion.

Several bodies such as Hyogo Prefecture, Amagasaki City, and the prot

management body have made reutilization plans for the canal area and/or the

waterfront. As of 1990, there are five such related plans. The Sea Blue Plan

shall be reviewed so it does not conflict with these plans. The five plans

deal basically with the following: (a) upgrading prot facilities, (b) activating the canal area, (c) setting up a desirable waterfront environment, (d)

activating industry in the reclaimed area, and (e) locating waste disposal for

the surrounding area. The characteristics common to all these plans is that

187
one of the functions of the canal and harbor area would be the provision of a

pleasant environment for sue by the people in the area.

Present Problems

and Future Challenges

However, to realize the utilization of the waterfront as a leisure

place, many problems still remain to be solved. Such problems are the purification of water and sediments, its function as hydrophilic space, coexistence

with industrial facilities, linkage with other plans, its function as a

disaster prevention facility, and regulations or laws which hamper the realization of the plan.

The contamination of the water in the canal, checked with indices of

dissolved oxygen (DO), biological oxygen demand (BOD), sulfide density, suspended solids (SS), color of water, and pollutant sedimentations, has progressed and is especially serious at the river mouth. The main cause of the

contamination of water is the flow-in of polluted water from rivers, and the

closed environment of the canals makes the situation worse. Flow-in water

from the river is expected to be reduces when the sewage improvement project

is completed in 1992. However, this project will not be taken into consideration in the Sea Blue Plan; in other words, the pollutant load from the rivers

will be assumed.

On the other hand, purification of water can be done by making good use

of differences in tidal level, but this method is impossible since the difference is merely 10 cm. If this method is chosen, electric-powered pumps should

be adopted for moving canal water.

In order to make the canal, which had been used for industrial facility

activities, a leisure place, problems still remain unsolved, such as the layout and shapes of existing structures and inaccessibility. Another problem is

that no green exists on the southern reclaimed land.

The canal, at the same time, should keep its original function as an

industrial facility. Conjunction between industrial facilities and leisure

place is the important matter in this plan. However, contradictions will

arise, if citizens can easily access the canal, since loading work at the area

will be frequently disturbed. Even though new structures will be built for

leisure purposes, it may not always be convenient for industrial use. At

present, this area is restricted for only industrial use so that structures

for leisure would also be restricted to some extent.

The canal area will have to fulfill the three functions of industry,

disaster prevention, and leisure place. The water drainage pump station and

lock which have been discharging excess water in the canal after a typhoon or

heavy rain should be maintained. The lock has been the only facility exchanging the water in and out of the canal, and this exchange should continue.

Basically, the canal will still remain as a closed water area like it is now.

188
Reviewing of Basic Concegt

Based on the previously described conditions, the method of how to

develop the canal area into a pleasant coastal environment will be explained

herein.

According to the flowchart on Figure 3, first, targets for improving

water and sediment environment (indicated by the five human senses) are set.

Second, the canal area is divided into zones for the creation of a pleasant

environment, third, measures on how to improve the water and sediment environment are established, and lastly more specific measures to create a pleasant are established. In any of the. measures taken, the existing functions of

the canal will not be distributed.

Setting targets for improving

water & sediment environment

F Zoning of the canal area ]

'I

Establishing measures to

improve water & sediment

environment

Establishing measures to

create a pleasant coastal

environment

Figure 3. Flowchart for

review of basic

concept

Zoning of the Canal Area for

a Pleasant Coastal Environment

In order to create a pleasant coastal environment which is full of

diversity, the area will be divided into four areas (Figure 4, Table 1). As

for zoning, the zones in the existing major plan were referred.

189
HANSHCI N LINE TI

isioiCni i •MATSUSNIMA

S~DRAINAGE ' • 'PUMP STATION

ARSI ATE

S=AAGASAKI S~LOCK

Fire 4. Zoning i of he canal area for a pieasant coastal environent

TABL 1. TARGET OF IMPROVEMENT OF EACH ZONE

AS A PLESAN COASTAL ENIRONMENT

ZONE CANAL INCLUDED TARGETS OF IMPROVEM ENT

Nishihori Canal

A Ogimachi Canal viewing level

Lock

B Kitahori Canal touching level

C Higashihori Canal touching level

Yomo-gawa River

D Nakahori Canal viewing level

Kyu-Samondono-gawa River

190
Target of Water and

Sediments Environment ImDrovement

The target of the improvement shall be at the level suitable for touching and viewing, although that level will differ depending on the zone. COD

will be adopted for checking the purification degree of the touching level of

water. According to the report of the Ministry of Construction, water quality

suitable for playing at the beach is below COD 5 mg/l. Thus, water in the

canal shall be purified to this level. From the correlation between COD and

transparency, COD is 8 mg/ 1 when the transparency is approximately 1 m. The

transparency of water in the canal area is almost the same as this figure, and

it means no further improvement is needed in respect to transparency. Rather,

the amount of floating garbage is adopted as the criterion for the pleasant

viewing level.

Thus, the target of improvement for viewing and touching, respectively,

is to lower COD to below 5 mg/l and to reduce floating garbages.

Ideas for Water and Sediment

Environment Improvement and the

Creation of a Pleasant Coastal Environment

In general, there are various methods for water and sediment environment

improvement. However, based on the characteristics of the Amagasaki canal

area as previously described, the f-llowing six methods should be adopted in

this plan. Merits and demerits of these methods will be explained herein.

One of the principal ideas of the Sea Blue Plan is not only water and

sediment environment improvement but also the addition of functions other than

the essential aim, e.g., some way for citizens to enjoy their life in the

pleasant coastal environment. As for the Amagasaki canal area, the following

points shall be deliberated in the realization of the plan:

#. Recreate a natural waterside.

b. Adopt the natural movement of water.

cg. Add artificial water structure in some places.

d. Create an ideal environment in which such species as water plants

and animals can live.

The following six ideas to improve water and sediment environment are

proposed:

_. River water conveyance.

(1) On the eastern and western sides of the canal area, there exist

Nakajima-gawa and Muko Gawa Rivers, respectively. Water of

both rivers is rather cleap, so water from these rivers shall

be taken into the canal area for improvement of canal water

through dilution or diffusion. Effective improvement could be

anticipated by this method, but the work of laying the pipeline

will be rather difficult. Furthermore, the cost of operating

pumps will be high if the pipeline covers long distance.

191
(2) Meanwhile, man-made streams shall be made along the canal area

for creating a pleasant coastal environment, and water taken

from the river will be used there. Fountains and waterfalls

can be made by utilizing the powerful force of water from the

outlet. Illumination can also be adopted for producing a marvelous effect at night.

(3) Utilization of water as previously described is not only producing a pleasant coastal environment but also purifying water

by supplying atmospheric oxygen to water since the time in

which water comes into contact with atmospheric air is

prolonged.

k. Sea water conveyance. Effective purification could be anticipated

by taking in seawater with the successive operation of the lock and

gates in the canal area. this method of water conveyance will contribute to the creation of a pleasant coastal environment.

-c. Porous bed channel,

(1) In the porous bed contact purification method, the biofilm

which forms on the surface of gravel will purify seawater when

water passes through the gravel.

(2) This method has been put in practice in sewage and river water

but never applied at seawater in Japan. The purification

facilities become large scale; however, the facilities can be

constructed underground, allowing the open space at the surface

to be used for multiple purposes. the facilities can also be

built into various marine and harbor structures, enabling them

to have the additional function of purifying seawater. In any

case, some problems still remain unsolved because this method

has the defect of clogging up sludge in the channel.

(3) The facility is large in size so that the best way for constructing it shall be underground of an open space in order to

use the surface for a park of some other purpose. One way to

use the purified water could be to channel it into a man-made

stream.

d. Living filter.

(1) The improvement method in which water plants, seagrasses, and

seaweed are being used is called a "living filter." This

method can take out nutrient salts but not without much difficulty. In respect to improvement, this method is not so highly

evaluated since a large area for planting water plants is

needed for effective improvement. Besides, there still remains

the problem of clearing the withered water plants. The characteristic of this method is to provide us with beautiful scenery

and a pleasant environment for birds and other animals.

(2) Here the purification of water is secondary. Rather, the

beauty of natural plants can be enjoyed. Also, the effect of

192
attracting wild birds and other animals and producing a play

area true to nature should be evaluated.

(3) This method plays an important role for human beings rather

than prominent improvement, as these water plants offer us

spiritual fulfillment by merely growing there. There is also

expectation that some new ecology of water plants could be

born. It is recommendable to plant them in the man-made stream

into which improved water will flow in.

.q. Dredging and sand-caDving. These methods are very basic or standard

ones so that they are the most positive ways for sediments improvement. A large amount of 'hedoro' (polluted sediment) had accumulated at the dead-end part of the canal area. These methods are

very effective especially for this kind of area. It is also possible to create new habitats for living creatures through the application of sand-capping materials and methods. A continuous dredging

or sand-capping will be required to sustain the improvement effect.

If the canal is changed to a habitat of living creatures, citizens

who utilize the area and its pleasant coastal space will be

comforted.

•. Retrieval of floating garbages., The retrieval of floating garbages

is the first thing to be tackles considering the canal area's external appearance. This method is also quickest way for the improvement of the canal. Movable equipment should be used because the

accumulation areas of garbage are not always the same. A barge

which is equipped with a garbage collecting system is recommendable.

The color or shape of the barge should be carefully deliberated so

as not to give ill feeling to the citizens who would be enjoying the

pleasant coastal atmosphere.

Reviewing of the Basic Plan

The outline of water and sediments improvement plan and conditional

values of application are described below.

A. River water conveyance,

(1) Clean river water (COD ca. 3.3 mg/l) will be taken into Zone B

(Kitahori Canal) from the Muko-gawa River, which runs through

the western side of the etanal area, for diluting the turbid

water of Zone-B (Figure 5).

(2) It is assumed that the length of pipeline form the water

in-take point of Muko-gawa River to the outlet at Kitahori

Canal is 930 m, and the quantity of water conveyed is Q -

6.0 m3/sec. The capacity of the water supplying pump (S) can

be calculated by the following formula:

S - 9.8 X Q X H/n

where

193
KITA HORI 04,

S•• MATSUSHIMA

PUMP STATION

S~PURIFICATION CHANNEL

AMAGASAXI•

LOCK

Figure 5. Arrangement of the purification facilities

S - capacity of pump

Q - rate of discharging

H - head loss

n - efficiency

then

S - 9.8 x 6.0 x 12/0.8 - 882

Thus, one - 900 kv pump shall be used.

k. Sea water conveyance.

(1) Two methods could be considered for seawater conveyance. One

of them is to operate the existing lock, gates, and drainage

pump station. The other one is the installation of a new pump

for water conveyance. In applying the former method, some

steps should be taken so as not to allow polluted water from

Shoge-gawa River to come into the canal.

194
(2) As for water conveyance, seawater should be taken in from Kitahori Gate and should be drained out through the fate by operating the gate and the lock adjusting in accordance with the sea

level or water level of the river. To avoid the flow-in of

polluted water from Shoge-gawa River, at first the fate of

Shoge-gawa River should be closed, then turbid water should be

discharged into the Kyu-Samondono-gawa River from Matsushima

Drainage Pump Station. Finally, the fate of Shoge-gawa River

should be opened to let cleaner water of the canal flow into

Shoge-gawa River (Figure 6). Successive operation of these

facilities should be carried out three times a week considering

the problems of pumping operation and maintenance. That is,

full-time operation of the pump is impossible due to the

following reasons: (a) the capacity of the pump is too large

(15 m3/sec) to be used for drainage; and (b) operation of the

pump is very complicated since a diesel engine is incorporated.

(3) As for the latter method, an exclusive pump (electric-powered

6 m3/sec) for drainage should be installed at a place close to

the Matsushima Drainage Pump Station to ensure full-time operation of pumping. A man-made current should be created for

changing the water in the canal by taking in seawater form the

Marushima Gate, Kitahori Gate, and also through the lock.

q. Porous bed channel.

(1) The porous bed channel was constructed on public lands linking

the downstream portion of Shoge-gawa River with the Higashihoro

Canal (Figures 5 and 7). The object is purification of water

from the Shoge-gawa River; the purified water will then be used

for replacing the water in the Higashihori Canal.

(2) The size of the canal is 2 m in depth, 20 m in width, and 100 m

in length; 0.18 m3/sec of turbid water will be purified by

placing gravels with a diameter of 100-150 mm (coefficient of

permeability is 100 cm/sec, and percentage of void is 35). The

retention time of running water in the channel is two hours

(flow velocity is 1.4 cm/sec). The channel is divided into

four blocks. The length of each block is 25 m. A trench runs

through the center of the bottom of the channel to receive

sludge accumulated on gravels. The purified water will be

temporarily stored in a tank built at downstream of the channel, then will be delivered to the edge of Higashihori Canal by

the pump at the edge of the channel (Figure 8).

(3) The disposal of sludge should be taken into account because

sludge always remains in the porous bed channel. The sludge

will accumulate in the trenches which run along the center of

the channel. Sludge should be disposed by underwater pumps

three or four times a year. A backwash pipe is also installed,

to clear clogging by sludge in the gravel beds.

195
A

4 am

Note: Sea level in the port below

OP + 1.35 m (ebb tide).

C3-

Note: Sea level in the port below

OP + 1.35 m (duration of

rise).

00

Z.4

Note: Sea level in the port

OP + 1.35 m.

Figure 6. Water anvement in the canal area by the seawater conveyance

196
S~MATSUSHIMA

DRAINAGE

SHOGE GAWA PUMP HOUSE.

BRUIDGE RIFICATION CHANNEL

PARK

-LIVIN FILTER

N M 0 FLOW OF PURIFIED WATER

Figure 7. Construction site of the channel type of purification facility

(4) The removal efficiency of COD and SS applied for this facility

is assumed to be the same figures as the examples of the river

water (30 percent for COD, 80-90 percent for SS), as no actual

data were obtained for seawater. Therefore, an experiment for

collecting such data is needed in the near future.

_. Living filter. Water plants such as reeds shall be planted in the

purified water drainage area at the far end of Higashihori Canal.

a. Dredging and sand-caoning, In the Amagasaki canal area, COD and

sulfides are down to sediment depths of 2 to 3 m. However, dredging

up such sediments is impossible in the canal area due to fear that

the stability of both sides of revetments will collapse. The only

solution is sand-capping. Originally, the purpose of sand-capping

was to prevent the solution of sludge, but recently, its role as

habitat for living creatures has been examined. The thickness of

sand-capping for the purpose of sludge solution prevention is

roughly 30-50 cm. If sand-capping is carried out to promote the

habitation of living creatures, the thickness of sand-capping should

be determined after studying the life history of organisms concerned. For instance, the well-known goby (Acanthogobius flavimanu) is known to dig 1.5 m holes in the seabed.

•. Retrieval of floating garbage. A movable barge equipped with garbage retrieval facilities shall be used considering construction

cost, workability, and suitability to the circumstances (Figure 9).

The size of the barge shall be 8 m wide and 4 m long. Water enters

197
C. CI .15.

1.49 

- - I- r54

d r, .21 .440

-01w

F . 4

198'
Figure 9. A ground plan of the barge for retrieval of

floating garbage

a slit in the barge and the garbage on the surface is trapped in a

cage inside the barge while the water flows out into the sea. The

suitable locations for setting the barge are the western side of the

Kitahori Gate, the western side of the lock, the easternmost end of

the lock, and the Higashihori Canal.

Forecast on Water and

Sediment Imrovement Effects

The first condition in the calculation was the assumption that COD in

the future will be the same as the present. Although the BOD of the river

water will be greatly reduced after the sewerage improvement works are completed, the COD will not show as clear a trend of reduction as BOD. The solution rate from sediment was assumed to be 4.5 mg/m 2 /day from the fact that the

amount of COD in the sand-capping material is 0.6 mg/l. The solution rate in

the future after the dredging of the Yomo-gawa River was deemed to be

1,020 mg/m 2 /day using the COD content of 136 mg/g in 1-2 m of sediment in the

Yomo- gawa River.

The simulation were carried out to six cases and shown below. Among the

six cases suggested, four methods are combined with the scheduled sewerage

improvement works.

199
CASE COMBINATION

CASE 1 Sewerage improvement (under planning)

CASE 2 Sewerage improvement and sand-capping for whole area

CASE 3 Sewerage importance and Muko-gawa River water conveyance

CASE 4 Sewerage improvement and porous bed channel

CASE 5 Sewerage improvement and drainage at Matsushima Drainage Pump House

CASE 6 Sewerage improvement and all four methods

Water purification effect in COD is shown in Table 2. According to the

effect forecasting calculation, no further improvement can be expected, when

only the sewerage improvement work is completed (CASE 1). Consequently, the

methods proposed in this report should be adopted for effective improvement in

addition to the sewerage improvement.

TABLE 2. EFFECT ON COD IMPROVEMENT BY THE FORECASTING CALCUIATION

(09/•)

PRESENT CASE CASE CASE CASE CASE CASE

OBSERVED CALC. 1 2 3 4 5 6

a. Shoge-gawa River 8.5 8.6 8.4 7.3 8.4 8.4 6.7 5.7

Shoge R. Bridge (4.8 - 13.0) (-0.2) (-1.3) (-0.2) (-0.2) (-1.9) (-3.1)

b. Yomo-gama River 5.5 6.7 6.2 4.9 4.6 6.2 5.8 4.0

Nakasu Bridge (3.9 - 7.9) (-0.5) (-1.8) (-2.1) (-0.5) (-0.5) (-2.7)

c. Lock 6.1 5.8 4.9 4.5 5.7 5.0 4.0

(4.6 - 7.7) (-0.3) (-1.2) (-1.6) (-0.4) (-1.1) (-2.1)

d. Niashhori Canal 5.0 4.9 4.9 4.2 4.9 4.6 3.9

Nishfhori Bridge (2.9 - 5.4) (-0.1) (-0.1) (-0.8) (-0.1) (-0.4) (-1.1)

e. Higashihori Canar 7.9 7.8 5.7 7.4 7.5 7.3 5.0

Tsukifj-Narush=s-mschi (-0.1) (-2.2) (-0.5) (-0.4) (-0.6) (-2.9)

Ahole Area 6.7 6.5 5.5 5.8 6.5 5.6 4.4

(-0.2) (-1.2) (-0.9) (-0.2) (-1.1) (-2.3)

Note: Naxiue and mminu values are in the parentheses in the coiwm 'observed'. The values in other

parentheses show the improvement effect.

The water inflow from Shoge-gawa River should be discharged from Matsushima Drainage Pump Station into Kyu-Samondono-gawa-River outside the canal

(CASE 5). Then, it is possible to reduce 1.9 mg/l of turbid water and even

200
reach to 6.7 mg/i. Besides, sand-capping for the whole area of the canal is

also effective. This method can reduce by 1.3 mg/i to 7.3 mg/i. Other

methods than the above mentioned are not so effective for purifying the waters

from Shoge-gawa River.

As for Yomo-gawa River, the other source of water inflow, taking water

in from Muko-gawa River will be effective (CASE 3). This method can reduce by

2.1 mg/i to 4.5 mg/i. The sand-capping for whole area will be also effective.

By combining these two methods, Kitahori Canal of Zone-B and Yomo-gawa River

of Zone-D will be improved.

For improvement of Zone-A (c,d) water intake from the Muko-gawa River is

effective (CASE 3). This method can reduce COD by 1.6 mg/i at the lock and by

0.8 mg/i at Nishihori Canal. Sand-capping (CASE 2) and drainage at the pump

station are also effective.

At Higashihori Canal of Zone-C, sand-capping for the whole area is prominently effective (CASE 2). This method can reduce COD by 2.2 mg/l, to

5.7 mg/i. Water intake from Muko-gawa River (CASE 3), porous bed channel

(CASE 4), and drainage at the pump station (CASE 5) are also more effective

than relying only upon sewerage improvement.

Table 3 shows transparency, which is another index of improvement. The

transparency is calculated by the following formula based on the correlation

between transparency and COD:

TABLE 3. EFFECT ON SS IMPROVEMENT BY THE FORECASTING CALCUIATION

(01/0)

PRESENT CASE CASE CASE CASE CASE CASE

CALCULATED VALUE 1 2 3 4 5 6

a. Shoge-gaew River 0.9 0.9 1.0 0.9 0.9 1.1 1.2

Shoge i. Bridge (40.0) (00.1) (U0.0) (00.0) (00.2) (+0.3)

b. Yow-gawa River 1.1 1.2 1.4 1.4 1.2 1.2 1.6

Nlaksau Bridge (.0.1) (00.3) (00.3) (00.1) (00.1) (00.5)

C. Lock 1.2 1.2 1.4 1.4 1.2 1.3 1.6

(U0.0) (00.2) (00.2) (20.0) (+0.1) (+0.4)

d. Nishihori Canat 1.3 1.4 1.4 1.5 1.4 1.4 1.6

Nishihori Bridge (00.1) (.0.1) (00.2) (+0.1) (+0.1) (00.3)

e. Higashihori CanaL 1.0 1.0 1.2 1.0 1.0 1.0 1.0

Tsukiji-Narushlmm-m.chi (tO.O) (+0.2) (*0.0) (*0.0) (*0.0) (.0.3)

Whote Area 1.1 1.1 1.3 1.2 1.1 1.2 1.2

(*0.0) (00.2) (00.1) (tO.0) (00.1) (.0.1)

Note: Vatues In the perenthescs show the Improvement effect.

201
Transparency - 4.106 x COD value -0.695

This table shows results of water improvement effect calculation at the

same points as the Table 2.

Transparency at the observation points range between 0.9-1.3 m. Judging

from this calculation, there is almost no improvement of transparency except

with the sewerage improvement (CASE 1). It is shown that the sand-capping

method (CASE 2) is the most effective solution of the six cases proposed in

this plan. In some areas, drainage from Nuko-gawa River showed great improvement (CASE 3). It is possible to realize at least a viewing level with the

use of any of these methods.

As noted previously, the sand-capping method has been especially effective. This method can be expected to produce satisfactory results without

combining other measures. The sand-capping method is suitable for the canal

area because it does not require any large facilities or a bit plot of land.

Besides, this method can reestablish habitats of living creatures. However,

the project cost is rather high, so it should be carried out step by step

according to the priority of work.

Image of Sea Blue

Plan at its Completion

The Sea Blue Plan proposes to create entirely new pleasant coastal environment by implementing measures to improve both water and sediment as well as

creative ideas. What kind of pleasant coastal atmosphere will have been

created in the canal area of Amagasaki after these six cases are jointly

applied for the basic environment improvement?

Zone-A (Nishihori Canal,

OfimachL Gate. the Lock Area)

A satisfactory viewing level can be achieved by purifying water through

seawater dilution and garbage retrieval with barges. The area around the lock

shall be open to citizens as a pleasant coastal park. From the park, the

daily work of the harbor can be observed (Figure 10).

Zone-B (Kitahori Canal)

The force of water at the outlet is so strong that it should not be

discharged directly into the canal; otherwise the outlet water will be mixed

with sludge at the canal bottom, increasing the turbidity of the water. In

order to avoid this phenomenon, a man-made stream should be constructed on the

shoulder of the revetment. The outlet water should be discharged there first

to weaken the force of the water. The water which is poured into the man-made

stream will flow into the canal with the effect of creating a waterfall.

Fountains shall also be constructed using this water power. Citizens can

enjoy the various atmospheres produced by the water around this area. Limitation of this area to navigational ships will be helpful in creating this environment (Figure 11).

202
-6rrA

"40

iF -7

~~ir

I~,. i" tit

C;

11

203
41

r4

4J 0

*0

0

44

0

r4

"-4

204
Zone-C (Higashihori Canal)

The porous bed channel shall be constructed underground of the present

Matsushima River Park. The water of the Shoge-gawa River will be purified

through the channel, then shall be drained at the end of Lhe Higashihori

Canal. Llving filter will be placed at the water discharge area to increase

the purification effect, as well as for a pleasant coastal atmosphere and

habitats of living creatures. The habitat of living creatures can also be

made by dredging and sand-capping. Water will be purified to a level with

which citizens can play (Figure 12).

Zone-D (Yomo-gawa River, Nakahori Canal. KMu-Samondono-gawa River)

This area cannot be used exclusively for a pleasant coastal purpose

because the navigation of ships takes the priority. However, this area is the

introductory part to the canal from the town, so that trees shall be planted

to make citizens feel like visiting the canal area.

Problems to be Settled Before Imolementation

In starting the project previously described up to this point, there are

many problems to be settled.

Setting the Targets for Improvement

The opinions of the citizens must be sufficiently reflected in setting

targets for the improvement of water and sediment as well as in the utilization thereafter.

Promotion of Technical Innovations

Among water and sediment improvement methods proposed this time, some of

them are already in practice like the sand-capping method, but others are not.

However, some have much promise such as the porous bed channel method used in

seawater. For solution of this problem, experiments of the porous bed channel

in seawater are needed as soon as possible. The Sea Blue Technology Research

Group of Japan Sediments Management Association and the Port and Harbor

Research Institute of the Ministry of Transport jointly have started the

experiment on a project scale since April 1990. Introduction of this experiment is also in the symposium literature.

In the sand-capping method, there is experience in practical use, there

are still problems about the kind of sand or a suitable thickness of sand

layer, in respect to habitats for living creatures.

Formation of an Implementation System

For the realization of the pleasant coastal improvement proposed this

time, several matters such as who will be responsible for the cost of project

and who will execute the project still remain unsolved and need to be

considered.

In the past, environmental improvement such as harbor and costal

improvement has been carried out with the aim of pollution prevention under

205
71l

m-,; ; ~1

03

"4J

.4)

444

0

bO

K 4r4

"Z4

206
regime of the Port and Harbor Law and pollution prevention laws. The Sea Blue

Plan aims to create a pleasant coastal environment which entails a broader

concept than pollution prevention, per se. Therefore, the existing systems

may not be sufficient to execute this ground concept, and it may be necessary

to consider a new system for the implementation of the plan.

207
SEA BLUE PLAN: EXPERIMENT OF SEA WATER PURIFICATION

BY POROUS BED CONTACT PURIFICATION METHOD

Yusuke Suda, Hideo Hamabata

Japan Sediments Management Association

Yasushi Hosokawa

Purification Hydraulics Laboratory

Port and Harbor Research Institute

ABSTRACT

A water purification experiment using channel

type of porous bed contact purification method has

been conducted since September 1990. This experimental facility is 30 meters long, 6 meters wide, and

1.5 meters in depth, and is separated into six independent channels 1 meter wide. Many kinds of water

and sediment quality and organisms were examined and

observed. Water qualities such as suspended solids,

turbidity, and transparency were exceedingly improved.

On the other hand, COD and TOC were not so effectively

improved, but about 20 percent of removal efficiencies

were gained. Many kinds of organisms were observed in

the biofilm and the channels. By means of the builtin channel into the harbor and structures as revetment, breakwater, etc., it is enabling them to have

the additional function of purifying sea water.

INTRODUCTION

The Sea Blue Plan, which we have proposed since 1987, is a project to

create a new coastal environment through both improvement and utilization of

it. In other words, it brings back a blue sea literally. The project is

characterized by the following five concepts:

A. Active creation of sea environment. The aim is to treat the sea as

an environmental resource whose wonderful value can be utilized to

actively create the environment.

k. Cose connection between land and sea, The link between land and

sea should be strengthened to foster familiarity with the sea

environment.

.q. Harmonizing environmental improvement and utilization. The plan

should promote not only the improvement of the environment but its

utilization by citizens at the same time.

A. Appreciation of natural features of the sea. In so doing, the characteristics of the sea, for example, currents, tide, waves, and

marine life, are not harmed.

208
j. ybrid technology, This concept involves the combined use of various kinds of relevant technology from low tech to high tech, mainly

those which utilize natural energy and/or biorelated technology.

Through the technical research on the Sea Blue Plan, we have reached the

conclusion that the porous bed contact purification method is a very effective

way for the purification of polluted seawater. This method, however, has been

hardly put in practice in seawater so far, although there are some practical

examples in river water and/or wastewater treatment process. Then, the Ports

and Harbors Bureau (Ministry of Transport), the Port and Harbor Research

Institute (Ministry of Trapsport), and the Sea Blue Technology Research Group

have started a study on the porous bed contact purification method since 1990

in order to evaluate the application possibility of this method to costal

waters. In this report, we will present a few of the conclusions of the

experiment and also show some images of the hybrid facilities utilizing the

porous bed contact purification method.

THEORY OF PURIFICATION BY POROUS BED CONTACT METHOD

So-called biofilm is naturally formed on the surface of the gravel and

other kinds of bed dipped in the seawater and other natural waters. Biofilm

consisted of many kinds of microorganisms. The biological activities of those

microorganisms such as feeding and decomposition of food materials purify

organic matters in the seawater. Another function of the biofilm is settling

and sedimentation of suspended solids in the seawater. Both biological and

physicochemical actions of the biofilm contribute to the purification. Those

functions are illustrated in Figure 1.

The porous bed contact method is one of the biofilm reactors. Three

types of the plant design were adopted, mainly in Japan and other countries.

They are the channel type, trickling filter type, and rotating contactor type.

In this experiment we adopted the channel type.

•Qblof Aim

pollutant matetters g gravel

decoposition adsorption

Figure 1. Purification mechanisms of the biofilm

(redrawn after Kasen-Kankyo, Kenkyu-kai,

ed. 1985)

209
METHODS OF CHANNEL EXPERIMENT

Plant

The experimental plant is constructed at the innermost part of the Tokyo

Bay which is facing Sunamachi-Kita-Unga Canal (Figure 2). Six independent

concrete-made channels, each 30 m long, 1 m wide, and 1.3 m deep, are laterally combined as shown in Figures 3 and 4. It is possible to practice a

variety of comparative experiments. Three sizes of gravels (andesite) are

used for the experiment. Channels No. 1, 2, 3, and 6 have gravels of mean

diameter 100-150 mm; channels No. 4 and 5 have 60-80 mm and 20-30 mm respectively. Gravels are put in the channels up to 1.2 m.

TOKYO (~

ITOKYO c'BAY

10 kmj

Figure 2. Experimental site

,..°.......... 30 ...... •.......O .. °........ °.. .4 . ..... .. °.°.. ... ..

* * 33400 - i4

z : 70037000

Z 50 70 7M 0 750-l

VW-1100 ý3404050 0 50 - 0 0 0

-2000:- __-- ___ __3___ -

0 0. 0OE 0E4

, ':o--PIT - -- • []Q[] ,2 -

z END PIT HEAD PIT

""N) I.T 0 WATER SAMPLING PIT, E P

N GRAVEL SAMPLING PIT

Figure 3. Ground plan of the experimental channel

210
Figure 4. A photo of the experimental channel

The experimental water is pumped up from the Sunamachi-Kita-Unga Canal

and directly into the head pit at the upstream end of the channel. The water

is running through the channel naturally and drained from the end pit. There

are three water-sampling pits (at 7.5, 15, and 22.5 m from the channel head)

and two gravel-sampling pits (at 4 and 19 m from the channel head). Pipes for

aeration and backwash are arranged on the bottom of channels No. 2-6.

Exoerimental Conditions

We conducted comparative experiments by setting different conditions for

(1) gravel sizes, (2) water velocity (HRT), and (3) presence or absence of

aeration (Table 1). The sunlight is cut off by dark plastic sheets placed

over the channels to prevent the primary production by photosynthesis.

TABLE 1. EXPERIMENTAL CONDITIONS

Channel Gravel size Aeration Retention Time Fixed flow velocity

(mm) (hours) (cm/sec)

1 100-150 none 4 0.5

2 100-150 none 2 1.0

3 100-150 none 1 2.0

4 60-80 none 2 1.0

5 20-30 none 2 1.0

6 100-150 none 4 0.5

211
Enough aeration is given in the head-pits of all channels. In channel No. 6, aeration is conducted in the whole length of the channel. In the

channels No. 2-5, the backwash by water and air-blown was operated six and a

half months after the beginning of the experiment because of clogging of the

channel.

After one month of preliminary experiment on the hydraulics of the channel, the purification experiment was started after October 1, 1990. Meanwhile, biological observations have been done four times in this experiment.

The first time is November 19, 1990 (two and half months after the beginning

of the experiment); the second time, January 30, 1991 (five months); the third

time, March 27, 1991 (six and a half months); and the fourth time, June 18,

1991 (nine and a half months).

Observation Items

The following water quality items have been examined to evaluate the

water purification effect.

.a. Water quality condition. The items examined were water temperature,

turbidity, transparency, suspended solids (SS), pH, salinity, chemical oxygen demand (T-COD, D-COD), total organic carbon (T-TOC,

D-TOC), NH3 -N, N02 -N, N03-N, T-N, PO4-P, and T-P. [Note: COD is

measured after the Japan Industrial Standard (JIS) procedure. This

COD expresses oxygen demand by KMnO4, with H2SO4 at 100* C for

30 minutes.

k. Condition of biofilm. The items used for the evaluation were

moisture content, Ignition Loss, org-C, Inorg-C, org-N, and Inorg-N.

•,. Condition of sediments. The items involved in the evaluation were

org-C, Inorg-C, org-N, Inorg-N, T-P, sulfide, COD, Ignition Loss,

pheophytin, grading composition, and specific gravity.

•. Organisms, The items examined for the evaluation were fauna in the

biofilm, flora in the biofilm, zooplankton, phytoplankton, benthos,

chlorophyll, heterotrophic plate count, and coliform group.

Items such as water temperature, salinity, turbidity, transparency, pH,

SS, COD, TOC, and dissolved oxygen (DO) were examined once every two days in

the period from October 1 to November 16; once a week in the period from

November 26 to March 29, 1991; and twice a week in the period after April.

Sample waters were collected at 10 A.M. in the period from October 1 to November 16. From November 26, samplings were conducted corresponding to the

retention time of each channel.

RESULTS

Purification Experiment

Water Purification Effect

A. Susoended solids (SS). Average SS concentration of influent was

5.7 mg/l, whereas it was 1.8 mg/l in the effluent through the whole

period (Table 2). SS was largely removed in the effluent, and high

212
'II

'i..~al g ;8 :R 81 0 it P- ;Qa a P, le

w cm I m m W; 1: V; W0 -4c; '0 c; el 0 V;m

0: Go 9% ei. a2 t a 4 0

14 m0 . 0. . . '~. cm' 6 ' A 4

W; Il W F. P - f- m 0, w -a m a t 0 i 'N% 

'0 IA '60 * O 4 0 t ' CIA 4 s- lot

Im In16

- - - -213
80 71.9

66al 66.5 65.3

60 5&S 52.3

w 40

j20

1 2 3 4 5 6

Channel No.

100 * Oct-- Deo 100 -C Juim- Feb,

80s 80-

so0 7. " M 60 5.7

40 401 23.6

0•

1 2 3 4 5 6 0 1 2 3 4 5 6

100 D Mw. - Apr. =10 [ May -- June 63 63.5

80 764763 7 .9 soe 80A 836. M

60 5760 47. 50.1

401 40

20 2D

01 1 0

1 2 345 6 1 2 34 5 6

Figure 5. Average removal efficiency of Ss (A: whole

experimental period from Oct. 1990 to June

1991; B: autumn/winter period from Oct. to

Dec.; C: middle winter period from Jan. to

Feb.; D: spring period from Miar. to Apr.;

and E: early summer period from May to June)

removal efficiency (52.3 - 71.9 percent in whole period) was gained

(Figure 5).

(1) Effects of each experimental condition on the removal efficiency and mass removed through the whole experimental period

are expressed first. The removal efficiency decreased with the

flow velocity among the channels with larger gravels (No. 1, 2,

3-flow velocity: 0.5, 1.0, 2.0 cm/sec). Thus, the efficiency

of channel No. 1 was 66.1 percent, whereas it was 52.3 percent

in No. 3. However, the removed weight notably increased from

94.1 kg (No. 1) to 259.5 kg (No. 3) as shown in Figure 6.

Among the channels with the same flow velocity (No. 2, 4 and 5 - flow velocity: 1.0 cm/sec), the removal efficiency increased

214
Total Experimental Period (Oct.---June)

500 488.0 ~ 0 VOLUME OF INMIUENT

400 N VOLUME OF FeAOVED

wU 300.2

2 300 S390 277.8 284.7

.. 7

>200 .6

(A 127.1 118.2

(a0100 94.

0

1 2 3 4 5 6

CHANNEL NUMBER

Figure 6. Average removed weight of SS in the whole

experimental period from Oct. 1990 to

June 1991

with the gravel size. The value of the large gravel (100-

150 -- ) channel No. 2 was 58.8 percent; the medium gravel (60-

80 mm) channel No. 4 was 66.5 percent; and the small gravel

(20-30 mm) channel No. 5 was 71.9 percent. No clear difference

between channel No. 1 (gravel size: 100-150 mm) with aeration

and channel No. 6 without aeration was recognized.

(2) Some seasonal differences were observed in Figure 5. Channel No. 3 (v:2.0 cm/sec, gravel size: 100-150 mm) always had

low removal efficiencies and showed large fluctuation. Channels No. 1 (100-150 mm, v:0.5 cm/sec), No. 4 (60-80 m-, v:l.0

cm/sec), and No. 5 (20-30 mm, v:l.0 cm/sec) each exhibited

similar changing pattern: the lowest values were found in

January 1991, and the values increased again after that. In

channels No. 1 and 2 the pattern almost corresponds to that of

the average SS load in the influent (0.22-1.37(0.61)g/m2/day

from October to December, 1990; 0.61-3.71(l.42)g/m2/day from

January to February, 1991; 0.47-3.77(l.50)g/mW/day from March

to April, 1991; 0.42-3.15(l.37)g/m2 /day from May to June).

(3) Figure 7 expresses the relationships between the effect on

improvement of SS and the elapse of the experiment. Until 30

to 40 days after the beginning of the experiment, the removal

weight of SS in the effluent were stable at about 0.2 to

0.3 kg/day. After 30 to 40 days, SS decreased and was stable

at about 0.1 to 0.2 kg/day until 60 to 90 days after the beginning of the experiment. However, SS in the effluent increased

again in the next period (until 150 to 180 days after the

beginning) and was showing some fluctuation. After 150 to

180 days, SS decreased again.

h. Chemical Oxygen Demand (COD). The average total chemical oxygen

demand (T-COD) in influent was 5.03 mg/l and that of soluted

215
(kg/dey) 1 10/ I- 6/30 (kg/day) 2 |0/ 1- 4/ 2

SS • INFLUENT • • " .~~EFFLUENT ,--..--'-,

40

0 • [4 0 -

CUMIULATIVE 80

STOCKED 00- 1 20-

(ko/dey) 3 I0/ 1- 3/31 (kg/day) 4 10/ I- 4/ 2

(kg/day) 5 10/ I- 4/ 2 (kg/day) 6 10/ I- 6/30

2

'F !-*-: . - - • .. •.. . . , .- _.0

-- '- __ .""'- " ' I'.:-'• •,r-"•. ' ,'". .

. .,' -. •.

40

so 40i120

Figure 7. Weight of SS in the influent and effluent and

the cumulative stocked SS

chemical oxygen demand (D-COD) was 4.3 mg/i through the whole period

(Table 3).

(1) The average removal efficiency in the whole period will be

shown first (Figure 8A). The removal efficiency is not so

high, and it is below 20 percent even maximally. Differences

among the channels with different flow velocity (retention

time) (No. 1, 2, 3 - gravel size: 100-150 m-, v:0.5, 1.0,

2.0 cm/see) are prominent, and the efficiency diminished with

the flow velocity. Thus, the values of channel No. 1 are 9.4

percent in T-COD and 7.5 percent in D-COD; those of channel

NO. 2 are 6.1 percent in T-COD and -2.0 percent in D-COD; and

those of channel No. 3 are -2.5 percent in T-COD and -5.5 percent in D-COD. The efficiency decreased with the gravel size

among the channels with the same flow velocity (No. 2, 4,

5 -v:l.0 cm/sec, gravel size: 100-150, 60-80, 20-30 mm). The

values of the smallest gravel channel No. 5 are 19.3 percent in

T-COD and 15.9 percent in D-COD; those of the medium gravel

channel No. 4 are 13.9 percent in T-COD and 8.5 percent in

216
4 '01 10 0:.o~~

4w C!

0., L --

F -K

:5 c

-r ~ 1I e m 0 It v0 % 0m m 0r4 a0 mn -S4 mIa W

I- CD

It .4 N e 4 In e qn n '0 Wt N In In N §n In

M I 't = tb.l

LI zw

00

'217
So A 3 T-COD

40 Oct.-e- June 3D-COD

S10 "39 2020 15.15o

2 3 4 5 6

Ch~annel No.

Oct.-Dec. 40 Jan. - Feb.

10 30

o ~ ~ Z _I • 1" -o

1 2 3 4 5 6 1 2 3 4 5 6

so ~50

40m May--June OMar.- DAe. 1

3 30

20 20

-10 - .10 1

-20 -20

I 2 3 4 5 6 1 2 3 4 5 6

Figure 8. Average removal efficiency of COD

(A: whole experimental period from

Oct. 1990 to June 1991; B: autumn/

winter period from Oct. to Dec.; C:

middle winter period from Jan. to

Feb.; D: spring period from Mar.

to Apr.; and E: early summer period from May to June)

D-COD; and those of the largest channel No. 2 are 6.1 percent in T-COD and 12.0 percent in DCOD. Aeration is effective to

improve efficiency. In channel No. 6 with the aeration, the

efficiencies are 15.9 percent in T-COD and 13.3 percent in

D-COD, whereas in channel No. 1 with no aeration, they are

9.4 percent in T-COD and 7.5 percent in D-COD.

(2) Some seasonal differences are also recognized in the removal

efficiency (Figure 8B-E). Generally, the removal efficiency of

T-COD had increased to March 1991 and then decreased in June 1991. Namely, channels No. 1, 4, 5, and 6 show almost the same

218
changing pattern. In these channels maximum values are beyond

20 percent. In channel No. 5 particularly, the efficiency

reaches about 40 percent in March, whereas the efficiency of

the channel No. 3 stayed at a very low level. Further, the

value of channel No. 2 in the June observation decreased all of

a sudden. On the other hand, the removal efficiencies of D-COD

have continually increased in all channels. Channels No. 1, 4,

5, and 6 show similar values which are rather high, but channels No. 2 and 3 exhibit extremely low values. The mean COD

load in the same season was: 0.65 (Oct.- Dec.), 0.60 (Jan.-

Feb.), 1.05 (Mar.- Apr.), and 1.36 g/m2/day (May - June).

,. Total organic carbon (T-TOC. D-TOC). The average T-TOC (Total

Organic Carbon) of the influent was 4.87 mg/l (Table 4).

(1) Effects of each experimental condition on the removal efficiency through the whole experimental period and are expressed

first (Figure 9A). Average removal efficiencies of T-TOC and

D-TOC are lower than 20 percent even in the maximum value.

Differences among the channels with different flow velocity

(retention time) (No. 1, 2, 3-gravel size: 100-150 mm, v:0.5,

1.0, 2.0 cm/sec) are observed, and the efficiency decreased

with the flow velocity. Thus, higher efficiencies are obtained

in channel No. 1 (16.4 percent in T-TOC and 9.1 percent in DTOC). Those of channel No. 2 are 13.1 percent in T-TOC and 5.9

percent in D-TOC, and those of channel No. 3 are 6.9 percent in

T-TOC and 8.1 percent in D-TOC. As for the difference of the

gravel size (No. 2, 4, 5-v:1.0 cm/sec, gravel size:100-150, 60-

80, 20-30 mm), the efficiency decreased with the gravel size.

The efficiencies of channel No. 5 with the highest values are

16.8 percent in T-TOC and 10.4 percent in D-TOC. Those of the

other two channels are No. 4 with 14.8 percent in T-TOC and 8.1

percent in D-TOC, and No. 2 with 13.1 percent in T-TOC and 5.9

percent in D-TOC. No clear difference between channel No. 6

with the aeration and No. I without aeration is recognized. In

channel No. 6 the efficiencies are 11.9 percent in T-COD and

4.4 percent in D-TOC, whereas in channel No. 1 they are 16.4

percent in T-TOC and 9.1 percent in D-TOC.

(2) Some seasonal differences are expressed in Figure 9. It seems

that the channels are divided into two groups with different

changing patterns. In T-TOC, channels No. 1, 3, and 6 have

maximum values in the January observation, whereas the maximum

values of channels No. 2, 4, and 5 are present in March. In DTOC, channels No. 1, 3, 4, and 6 have maximum values in January, whereas those of the channels No. 2 and 5 are present in

March. The mean TOC load in the same season was: 1.18 (Oct.-

Dec.), 0.99 (Jan.- Feb.), 0.84 (Mar.- Apr.), and 1.44 g/cm2/day

(May-June).

. Turbidity The average turbidity of the influent is 3.5-5.5 deg,

and that of the effluent is 1.6-2.0 deg in the total experimental

period.

219
n- W! R 4

"" ~ I& 4I - n0 4i N 4! - 0 , 4 1 , C21 -I

a C ~ 4 N %IC' 4 N '01 N C, 4NI 41

1- an N N % 0'0 a 0 m an N n an Ný 4ý n 0 9 an

*1 *W!0 C

cm M y .

W 0 Ncm an -cm W N m 'a -m 4 N m 4 N% W;

s. o N cm an 4 m cm 4

an S 4 in~ N m &0 o fmn 't N. 4 an 'S a F N;

- E Vb N cm an m N0 m a 04..Nm = -

.220
50 A Oct.-- june o T-TOC

40 ED-TOC

S 30

20 16.4 &1 14.8 16.411.9

-10

-20 2 3 4 5 6

Channel No.

50 B ct.-Dec. 50 C

40 40 Jan. - Feb.

30 30

20 20

10 n .- n Fl Fl °10

0 0

-10 .10

-20 1 2 3 4 5 6 201 2 3 4 5 6

so 50

50 D Mar.--Apr. 40 E May- June

4040

30 30

20 20 ,

10 F6 m a 10 r0n

0 0

10 -10

.201 2 3 4 5 6 201 2 3 4 6

Figure 9. Average removal efficiency of the TOC

(A: whole experimental period from Oct.

1990 to June 1991; B: autumn/winter

period from Oct. to Dec.; C: middle

winter period from Jan. to Feb.; D:

spring period from Mar. to Apr.; and

E: early summer period from May to

June)

j. Transoarency.

(1) The average transparency of the influent was 40-150 cm (mean

94 cm) during the whole experimental period, although there

were some exceptions (Table 5). We have been using an ordinary

100-cm cylinder -.nd special 150-cm and 200-cm cylinders depending on the water quality. In many cases (45-89 percent), the

transparency of the treated effluent was over 200 cm.

221
10,

0.. N- -ý -1 I IMImC

CC

U % - - -N - v -

CC

4; C 10 C C. .

u mz 0 .- 00

I- z I Nl Nl N I I I-, E i Z

cm VAtW%1

2 222
(2) Difference of efficiencies among the channels with different

gravel size is recognized. The efficiency of channel No. 5

with the small gravel (mean diameter 20-30 -m) is the highest

throughout the whole experimental period; however, the difference between the channels No. 4 and No. 2 with medium and the

largest gravel (No. 4, 2) is not clear.

(3) In comparing the presence or absence of aeration, the transparency of the nonaerated channels No. 1-5 is slightly better

than that of the aerated channel No. 6.

•. Dissolved oxygen (DO). In channel No. 6 in which the aeration has

been conducted over the entire length, 3-12 mg/l of DO has been

sustained during the whole experimental period. In other channels,

aeration was conducted only at the head-pit. Therefore, DO is

rapidly consumed by the endogenous respiration of the biofilm and

the decomposition of the polluted matters. Some examples of the DO

profile of channels with different gravel size (No. 2, 4, and 5) are

plotted against channel length in Figure 10. DO rapidly diminished

in the channel with the smaller gravel.

10

_A8 -- Cannel 2

Cannel2

Es -- Cannel 5

104

0 4-

2

0 - -- -

0 7.5 15 22.5 30

(in)

Figure 10. DO profile in the channels with

different gravel sizes (No. 1, 2, 3)

Relationships Among the Water Quality Indices

Indices relating to turbidity (SS, transparency, turbidity) have relatively strong interrelationships. The correlation coefficient between SS and

transparency is -0.704, SS and turbidity is 0.639, and transparency and turbidity is -0.725 in the influent during the total experimental period.

Meanwhile, in the effluent the correlation coefficient between SS and

transparency is -0.692, SS and turbidity is 0.313, and transparency and turbidity is -0.420. The correlation coefficients of the effluent are slightly

smaller than those of the influent. No clear relationships between SS and COD

and SS and TOC in both influent and effluent were recognized.

223
Organisms in the Channel

More attention has been paid to the biological aspects in the biofilms

and channels, because these matters are scarcely known in connection with

polluted coastal seawater in spite of the importance of organisms in the biofilm and channels for purification. As for microorganisms inhabiting the

biofilm in river water and sewage purification facilities, many authors have

repeatedly reported on those aspects (e.g., Hashimoto and Teranishi 1988;

Inamori 1989; Inamori et al. 1987; Kuniyasu 1988; Sudo, ed. 1988, 1989; Sudo

and Inamori 1989; Tsuda 1982). In the polluted seawater, however, there have

only been a few reports (e.g., Otsuki, 1990). Higher classification of the

organisms follows by Yamada, ed. (1983).

Microanimals in the Biofilm

A. Changes of fauna.

(1) A total of 36 species of microanimals were observed in the biofilms. They are classified into two subkingdoms (Protozoa and

Metazoa) and further into six phylla (Protozoa, Rotifera, Nematoda, Annelida, Arthropoda, and Mollusca). The number of species in each phylum is Protozoa 28; Rotifera 3; Arthropoda 2;

and Nematoda, Annelida, and Mollusca 1. All species of the

phylum Protozoa are included in the class Ciliatea. Three

species of the Metazoa were present as larvae: polychaete

larvae of Annelida, D-larvae of Mollusca, nauplius larvae of

Arthropoda. The dominant five species in each observation are:

(a) Nov. 19, 1990 Total number of individuals: 1,771 N/cm2

Total number of species: 7 species/cm2

Carcheslum sp. (77.9 percent), Vorticella sp. (10.1 percent), Nematoda sp. (9.3 percent), Ciliatea sp. (1.6 percent), Dystreria sp. and Loxophylum sp. (0.4 percent)

(b) Jan. 30, 1991 Total number of individuals: 5,115 N/cm2

Total number of species: 14 species/cm2

Vorticella sp. (70.7 percent), Carchesium sp. (10.3 percent), Zoothamnium sp. (3.9 percent), Ciliatea sp.

(3.7 percent), Dlophyris sp. (2.7 percent)

(c) Mar. 27, 1991 Total number of individuals: 4,929 N/cm2

Total number of species: 29 species/cm2

Zoothamnium sp. (53.5 percent), Eutintinnus sp. (9.0 percent), Helicostomella fusiformis (7.0 percent), Vorticella

sp. (6.8 percent), Tintinnopsis kofoid. (6.4 percent)

(d) June 18, 1991 Total number of individuals: 1,479 N/cm2

Total number of species: 18 species/cm2

Peritrichida sp. (62.5 percent), Nematoda sp. (11.4 percent), Zoothamnium sp. (5.5 percent), Helicostomella sp.

(5.1 percent), Monostyla sp. (3.9 percent)

(2) The primary dominant species accounts for 53.5-77.9 percent of

the total number of individuals. Almost all dominant species

were protozoans except Nematoda sp. (Nov. 1990, June 1991) and

224
Monosytla sp. (Rotifera) (June 1991). All dominant species in

the first two observations were freshwater species, whereas

some marine species (EutLntLnnus, Hellcostomella, TintlnnopsLs)

were present in the last two observations. Some of the dominant species are illustrated in Figure 11.

B C

A

Vorticell nebulifera

Carchesius polypinuA Z1othamnium PygmaeuA

Figure 11. Some of dominant microanimal species in the

biofilms - A: Carchesium polyplnum,

B: Vorticella NebulLfera, and C: Zoothamnlum

pygmaeum (A & B: after Mizuno 1990; C: after

Sudo & Inamori 1989)

b. Changes of the number of individuals. Number of individuals

increased with flow velocity (Figure 12). Thus, among the channels

No. 1, 2, and 3 (gravel size: 100-150 mm, v:0.5, 1.0, 2.0 cm/sec),

channel No. 3 had the maximum number in both upper and lower part of

the channel. No clear differences were found in the channels with

different gravel sizes (No. 2, 4, 5-v: 1 cm/sec; gravel size: 100-

150, 60-80, 20-30 mm). Aeration was not so influential on the number of individuals. In the upper part of the channel, the number in

channel No. 6 with aeration was slightly larger than that of channel

No. 1, but the reverse tendency was recognized in the lower part.

In the same channel, the microanimals in the upper part always outnumbered the lower part except No. 3.

•. Changes of the dry weight of the biofilm. I.ý the upper part of

channels No. 1, 2, 4 and 6, the dry weight (mg/100 cm2 ) increased

with season but decreased in channels No. 3 and 5, whereas there

were no clear tendencies in the lower part. Effect of the flow

velocity was recognized between channels No. 1 and 3 (gravel diameter: 100-150 m; v:0.5, 2.0 cm/sec). The dry weight of channel

No. 3 was larger than that of channel No. 1. The dry weight

decreased with the gravel size in the upper part of the channel in

No. 2, 4, 5 (v:l cm/sec; gravel diameter: 100-150, 60-80, 20-30 mm),

but the reverse tendency was found in the lower part. No distinct

difference due to aeration was found between channels No. 1 and 6

(Figure 13). In the same channel, the dry weight in the upper part

was larger than that of the lower part.

225
suNov. 19. 1990 2111Jan. 30. 1991

IfMt

i4M~

IMI

lowI( S'M

w s l aa'

III le 53 04 55 1160 111 12 3 4 11 06

Mar~ 191O 27PE unW1.E99

Fiue1.Cane ftenubro nivdaso1h

miraiml N/m2 i h boim

521 spce.O he5 pce f h hoohta 8aese

cis h cas f acllropy s (da-os..h.omnn

fiveseisi ahosrainae

Figur 12n. Chage of9 Thea number of inivduls: of06 thel

(1)~~~ toalof6 Aube ~Toa of miragewreosre.Tey species: aes

lageyclssfedinophll yaopyaDiohyaCroo
Skeletonem costatuwl (49.0 percent). Navicula spp.

(20.9 percent), Rhlzoaolenla aee.Lgera (6.4 percent),

Nltzchla spp. (4.3 percent), Cymbella sp. (2.9 percent)

(c) Mar. 27, 1991 Total number of cells: 251,047 cells/i

Total number of species: 32 species/1

Skeletonema costatum (93.2 percent), Rhlzosolenla uetlgera

(4.5 percent), Nav~cula spp. (0.7 percent), Nltzschla app.

(0.5 percent), Chaetoceroa sp. (0.4 percent)

2WNov. 19, 1990 2"Jan. 30. 1991

'IBM

l50 JI

*M U

111 32 3 34 05 tie 111 12 113 114 as 46

Mar. 27. 1991 14M June 18. 1991

low

,1low

.2~am

3 .2M

31 32 33 44 35 16 Ill 02 03 04 35 W6

M uMRm T LOWER

Figure 13. Changes of the dry weight (mg/l00 cm2)

of the biofilm

(d) June 18, 1991 Total number of cells: 14,643 cells/i

Total number of species: 21 species/I

Skeletonema costatum (87.0 percent), Rh.Lzosolenla set.Lgera

(4.4 percent), Nav~cula spp. (3.3 percent), Meloslra nummulo.ldes (2.2 percent), Nltzschla spp. (1.2 percent)

(2) The primary dominant species accounts for 87.0-96.4 percent of

the total number of cells except the January observation when

the proportion of dominance was 49.0 percent. Skeletonema

costatum and NavIcula spp. were present in all seasons as dominant species. Particularly, S. costatum primarily dominated in

227
January, March, and June observations. All dominant species

are marine inhabiting. Some of the dominant species are illustrated in Figure 14.

BC

Navicula elegans

Skeletonewa costatum

Aphanothece saxicola

Rhizosolenia set igera

Figure 14. Some of dominant microplant species in the biofilas

A: Aphaenothece saxLcola, B: Skeletonema costatum,

C: NavLcula elegans, and D: Rhlzosolenla setlgera

(after Mizuno 1990)

b. Changes of the number of cells. The number of cells increased with

flow velocity in the channels No. 1, 2, and 3 (gravel size: 100-

150 mm; v:0.5, 1.0, 2.0 cm/sec) as shown in Figure 15. Effects of

the gravel sizes and the aeration were not recognized.

Zooplankton

A. Changes of fauna.

(1) A total of 55 zooplankton species were observed. They are

firstly classified into two subkingdoms, Protozoa and Metazoa.

The former has only one phylum Protozoa. But the latter is

further classified into five phylla (Rotifera, Nematoda,

Annelida, Arthropoda, Mullusca). The protozoans and metazoans

are different in their body plan and body sizes. As for the

body plan, the former is unicellular and the latter is multicellular. The body sizes of the protozoans are 30-500 Am, and

those of the metazoans are 300 pm-1.5 mm in the species which

were collected in the present study. The number of species in

each phylum is: Protozoa 38, Arthropoda 7, Rotifera 6, Mollusca 2, and Nematoda and Annelida 1. All species except one

(Amoeba) are included in the class Ciliatea. Five species of

metazoans are larval forms: polychaete larvae of Annelida,

nauplius larvae of Copepoda and Cirripedia (Arthropoda),

D-larvae and Umbonium larvae of Mollusca. The dominant five

species in each observation are:

228
IN Nov. 19. 1990 - Jm. 30. 1991

m -a

C S. C k so so

em .1 .3 t

S27 1991 •3M June318, 199

, " W. Ism , S. •L

I is

2I 1 . I IIt.

Ism

is

.3:j

112 13N 2 3N

Figure 15. Changes of the number of cells of the microplants

(cells/1) in the biofilm

(a) Nov. 19, 1990 Total number of individuals: 534 N11

Total number of species: 18 species/1 Tlntlnnopsls beroldea (30.3 percent), Strombldlum spp.

(14.6 percent), Dystrerla spp. (13.5 percent), nauplius

larvae of Copepoda (11.2 percent), Monostyla sp.

(10.1 percent)

(b) Jan. 30, 1991 Total number of individuals: 1,020 N/11

Total number of species: 16 species/1

Tlntlnnopsls beroldea (30.5 percent), Strombidlum spp.

(17.4 percent), Carcheslum spp. (13.2 percent), Stromb1lldlum spp. (10.0 percent), DldInIum natusum (8.8 percent)

(c) Mar. 27, 1991 Total number of individuals: 6,564 N11

Total number of species: 23 species/1

Str-omblildlum spp. (69.8 percent), Zootha nlum spp.

(6.4 percent), Eutintinnus rectus (5.7 percent), Eutlntlnnus turrls (2.7 percent), Hellcostomella fuslformis

(2.4 percent)

(d) June 18, 1991 Total number of individuals: 1,380 N/11

Total number of species: 17 species/1

229
PerltrLchlda sp. (25.2 percent), T7ncLnnopsas berold"a

(22.6 percent), nauplius larvae of Copepoda (13.0

percent), Ifonostyla sp. (10.4 percent), Hellcostomella

long& (7.8 percent)

(2) Proportion of dominance (25.2-69.8 percent) is rather low compared with other microorganisms. The most dominant species are

protozoan except two metazoans (nauplius larvae of Copepoda and

Monostyla of Rotifera). Both marine and freshwater species are

included in the dominant species: marine - Tlntlnnopsls, Hellcostomella, EutLntinnus; and freshwater - Strombldlum, Strombildium, Carcheslum, Ptdlnlum, Zoothammlum, Monosytla. Some

of the dominant specieb are illustrated in Figure 16.

C

B

A

6.0:

Eutintinnus turr/s

ffelicostomel/a fusiformis

Tint innopsis beroidea

Figure 16. Some of the dominant zooplanktons - A: TlntInnopsls

beroidea, B: Eutintinnus turris, and C: Helicostomella fom&ls, (after Minuno 1990)

k. Decreasing tendencies of the number of species and individuals. In

some cases, species which were not present in the influent were

observed in the channel. Those species not observed in the influent

are omitted here.

(1) Figure 17 expresses the differences of the removal efficiencies

on the number of individuals among channels. The removal efficiency reduced with flow velocity. Among channels No. 1, 2 and

3 (gravel diameter: 100-150 mm; v-0.5, 1.0, 2.0 cm/sec), the

highest value was obtained in channel No. 1. The efficiency

diminished with gravel size, and the highest value was obtained

in channel No. 5 which has 20 to 30-mm-diam gravels. A low

efficiency value was expressed in channel No. 6 with aeration

compared with channel No. 1 without aeration.

230
2U

i Iy

CH.1 04.2 01.3 0H.4 04.6 04.6

0#*#EL

Nov. 19. 1990 Jan. 30. 1991

--' Mar. 27, 1991 E-- June 18. 1991

Figure 17. Removal efficiency of the zooplankton

(2) Secondly, the differences in the removal efficiencies between

the protozoans and metazoans are compared (Figure 18) because

these two groups are different in body size. The efficiency

decreased with flow velocity in both protozoan and metazoan

(No. 1, 2, 3) and with gravels size (No. 2, 4, 5). In No. 6

with aeration, the value was lower than channel No. 1 without

aeration. No consistent difference was recognized between the

protozoans and metazoans, although some tendencies were recognized during certain months. That is, the efficiency was high

in the protozoans and low in the metazoans in November; no

clear difference was found between them in March; and the value

was high in the metazoans and low in the protozoans in the

January and June observations.

Phytoplankton

A. Changes of flora.

(1) A total of 59 species of phytoplankton were observed. They are

largely classified into phylla Cyanophyta, Dinophyta, Chromophyta, Euglenophyta, and Chlorophyta. The number of species in

each phylum is: Chromophyta 44, Dinophyta 11, Euglenophyta 2,

and Cyanophyta and Chlorophyta 1. Forty-one species of the

Chromophyta are included in the class Bacillariophyceae (diatoms). The dominant five species in each observation are:

231
Nov. 19, 1990

.1 'U Jan. 30. 1991

at 0 as u tlero I03 

ta Mar. 27. 1991

SJune 18. 1991

6 p U

-- 28 l-•

lliii

-681

01 1l2 Sl3 4 453 us

i PROOZOA ---- METAZOA

Figure 18. Differences in removal efficiency between the

protozoans and metazoans in the zooplankcton

(a) Nov. 19, 1990 Total number of cells: 1,241,600

cells/1 Total number of species: 14 species/1

Skeletonema costatum (82.7 percent), Euglenophyceae sp. (13.1 percent), Nitzschia spp. (2.1 percent), Cymbella sp.

(1.3 percent), Navicula spp. (0.5 percent)

(b) Jan. 30, 1991 Total number of cells: 890,400 cells/1

Total number of species: 30 species/1

Skeletonema costatum (76.9 percent), Rhizosolenia setigera (12.9 percent), Navicula spp. (4.3 percent), Cyclote1la

spp. (1.1 percent), Nitzschia sp. cf. pungens

(0.7 percent)

(c) Mar. 27, 1991 Total number of cells: 1,945,360

cells/l

Total number of species: 29 species/1

Skeletonema costatum (93.4 percent), Rhabdonema arcuatum (2.6 percent), Nitzsch1a sp. (0.6 percent), Navicula spp.

(0.5 percent), Chaetoceros didymum (0.4 percent)

232
(d) June 18, 1991 Total number of cells: 7,960,736

cells/i

Total number of species: 18 species/1 Skeletonema costatum (99.7 percent), Navlcula spp. (0.1 percent), Amphiprora sp. (0.04 percent), Cyclotella

spp. (0.04 percent), KelosLra numuloldes (0.04 percent)

(2) The primary dominant species accounts for 76.9-99.7 percent of

the total number of cells. Only one freshwater species (Cym- bella) was observed in the dominant species in the November

observation. The habitat of the other species is marine.

]. Decreasing tendencies of the number of species and cells. In some

cases, species which were not present in the influent were observed

in the channel. Those species not observed in the influent are

omitted here. Figure 19 shows the difference in the removal efficiency on the number of cells among the channels. The removal effi- ciency decreased with flow velocity. In channels No. 1, 2, and 3

(gravel diameter: 100-150 mm; v:0.5, 1.0, 2.0 cm/sec), the highest efficiency was obtained in channel No. 1. The efficiency declined

with gravel size, and the highest value was obtained in channel

No. 5 which has 20 to 30-mm-diam gravels. A low value of the efficiency was expressed in channel No. 6 with aeration compared with

channel No. 1 without aeration.

20 a .3.19 Ho.1.19 

-20

SMar. 27, 1991 [• June 18. 1991

Figure 19. Removal efficiency of the phytoplankton

Large Sessile Animals

Other than the above microorganisms, many kinds of large size sessile and benthic animals were observed in the biofilm, in the pipes, and on the channel walls (Figure 20).

233

U i ini:n:i'i• m|a i N H
Neanthes japonica tubes of Ficoposatus enigmaticus

Serpul idae

Corophium crassicorne

Figure 20. Some of representative sessile animals observed on the

gravels and channel walls - A: a nereid Neanthes

japonica, B: a species of Serpulidae, C: a serula

Ficopomatus enigmaticus on the channel wall, D: a

bivalve Mytilus edulls on the wall of the head

pit, and E: an amphipod Corophium crassicorne,

(A: after Akiyama & Matsuda 1974; B: after FuchakuSeibutsu Kenkyukai 1986; D: after Shiino 1969)
A. Phylum Cnidaria

Hydrolda sp.

k. Phylum Annelida, Class Polychaeta, Order Errantia

Neanthes japonica

Neanthes succinea

Hesionidae sp.

Capltella sp.

q. Phylum Annelida, Class Polychaeta, Order Sedentaria

Ficopomatus enigmaticus

Hydroides ezoensis

Polydora sp.

d. Phylum Mollusca, Class Pelecypoda, Order Dysodonta

Mytilus edulis

Musculus senhousia

Limnoperna fortunei kikuchii

_. Phylum Arthropoda, Class Crustacea, Order Thoracica

Balanus improvisus

.•. Phylum Arthropoda, Class Crustacea, Order Amphipoda

Anisogammarus sp.

Corophium sp.

Coliform Groups and Heterotrophic Plate Number

Both the coliform groups and heterotrophic plate number reduced in the

effluent (Table 6). The number of the coliform groups in the influent ranged

from 490 to 27,000 (mean 13,623) MPN/100 ml, but those in the effluent ranged

from 17 to 3,300 (mean 1,101) MPN/100 ml. On the other hand, the number of

the heterotrophic plate in the influent ranged from 1,600 to 67,000 (mean

88,900) CFU/ml, but those in the effluent ranged from 70 to 34,000 (mean

5,287) CFU/ml.

The removal efficiency of the coliform group among channels was affected

only by the presence or absence of the aeration. In channel No. 1 (not

aerated) and No. 6 (aerated), high removal efficiency was found in channel

No. 6. Average removal efficiency was 80.6 - 99.7 percent. However, on January observation the value in channel No. 1 was 44.9 percent.

Meantime, the removal efficiency of the heterotrophic plate number shows

the same tendency as the coliform group. Average removal efficiency was not

so constant as compared with the coliform group, but removal efficiencies of

over 80 percent were shown in some cases.

Chlorophyll a

Chlorophyll a in the influent ranged from 3.9 to 32.5 pg/l (min: Jan.

1991; max: June 1991), but in the effluent was about 2 pg/l (Table 7). No

particular tendencies according to differences in the experimental conditions

were found.

235
TABLE 6. NUMBER OF THE COLIFORM GROUPS AND THE HETEROTROPHIC PLATE

NUMBER AND THEIR REMOVAL EFFICIENCIES

Coliform Group (MPN/100 ml)

INFLUENT #1 #2 #3 #4 #5 #6

Nov. 1990 27000 1300 3300 2400 2200

Jan. 1991 490 270 33 17 17

Mar. 1991 10000 700 490 1300 330 330 33

June 1991 17000 1300 3300 1700 1300 1000 700

Removal Efficiency (%)

Nov. 1990 95.2 87.8 91.1 91.1

Jan. 1991 44.9 93.3 96.5 96.5

Mar. 1991 93 95.1 87 96.7 96.7 99.7

June 1991 92.4 80.6 90 92.4 94.1 95.9

Heterotrophic Plate Count (CFU/ml)

INFLUENT #1 #2 #3 #4 #5 #6

Nov. 1990 67000 8000 8400 34000 26000

Jan. 1991 1600 350 320 230 180

Mar. 1991 3300 2700 720 140 70 370 250

June 1991 17000 5500 1300 12000 1700 220 3300

Removal Efficiency (%)

Nov. 1990 88.1 87.5 49.3 61.2

Jan. 1991 78.1 80 85.6 88.8

Mar. 1991 18.2 78.2 95.8 97.9 88.8 92.4

June 1991 67.6 92.4 29.4 90 98.7 80.6

TABLE 7. CHLOROPHYLL a AND ITS REMOVAL EFFICIENCY

CHLOROPHYLL a (u//l)

INFLUENT #1 #2 #3 #4 #5 #6

Nov. 1990 9.5 1.4 0.4 0.6 1.3

Jan. 1991 3.9 1.3 1.7 0.2 2.5

Mar. 1991 7 1.3 1.4 1.7 0.6 0.6 2.8

June 1991 32.5 1.3 5.9 5.4 3.9 3.4 3

REMOVAL EFFICIENCY (%)

#1 #2 #3 #4 #5 #6

Nov. 1990 85.2 95.8 93.7 83.6

Jan. 1991 66.7 56.4 94.9 35.9

Mar. 1991 81.4 80 75.7 91.4 91.4 60

June 1991 96 81.8 83.4 88 89.5 90.8

DISCUSSION

Purification Effects of the Exverimental Channels

Nakamura and Sakai (1987) divided 220 days of river water purification

experiment into four subperiods according to the purification effect on SS.

The first is the first stable period (0 to 40th day) when very good purification proceeded; the second is the transition period (40 to 90th day) when the

water quality of the effluent is affected by the purification process; the

236
third is the instable period (90 to 150th day) when the values of influent and

effluent are sometimes reversed; and the fourth is the stable period (150 to

220th day) when good purification is proceeding.

A pattern similar to above is also recognized in our experiment. From

the relationship between the improvement effect of SS and the elapsing time of

the experiment (Figure 7), it is assumed that there are four subperiods in the

whole experimental period:

A. 1st Period: 0 to 30-40th day

Sufficient purification effect is not yet attained.

k. 2nd Period: 30-40th to 60-90th day

Stable purification is proceeding.

c. 3rd Period: 60-90th to 150-180th day

Unstable period.

d. 4th Period: after 150-180th day

Stable purification is proceeding again.

The removal efficiency of BOD in river and sewage waters is generally in

the range from 50 to 90 percent (e.g., Inamori et al. 1990, Kiriku et al.

1984, Nakamura and Sakai 1987; Osanai 1990; Sekiyama et al. 1987; Tsuchiya and

Izumi 1983, 1984); and that of COD is in the range from 20 to 50 percent

(e.g., Osanai 1990; Sekiyama et al. 1987; Tsuchiya and Izumi 1983, 1984).

Meanwhile, the removal efficiency of COD in the seawater is about 15 percent

(Otsuki 1990) and 27 to 38 percent (Tazawa et al. 1991), although only a few

examples are available. In the present experiment, the average removal efficiency of COD through the whole experimental period is below 20 percent (Figure 8A). This value is somewhat lower than those of the previous experiments,

but some channels exceed 20 percent and even 30 percent depending on season.

The removal efficiency is largely affected by the gravel size. Thus,

the efficiencies of the smallest gravel channel (#5) is always the highest.

However, small gravel is ineffective, or sometimes has adverse effects on the

normal orientation of the channel. Actually, the operation of channel #5 was

suspended on September 1991 because of the clogging of the channel despite

several backwash attempts.

The removal efficiency of SS decreased with flow velocity. Meanwhile,

the removed weight increased with the flow velocity.

Although no clear improvements are recognized in SS by aeration, the

aeration will be effective on COD in the season with high polluted load. On

the other hand, aeration promotes resuspension of biofilm from the gravel, and

it caused low transparency in channel No. 6, particularly during the low temperature period with little suspended solids (Table 2). This result means

that the aeration is not effective or is rather conversely effective on

improvement of the transparency during the low temperature period. The above

purification effects of the experiment are summarized in Table 8.

237
aird C xU.4

wx t

12-

0

,-

ww

4- .4. UA UA l a

08 l I"

(n (a CK x r- t- 41 w x

4-238
Microorganisms in the channel

In general, the number of species and individuals increases with time

with some fluctuation (succession). Finally, the ecological succession

reaches a stable biotic community (climax) which is in equilibrium with the

existing environmental condition.

In this experiment, the number of microorganism species in the biofilm

and the plankton increased toward spring (Mar. 1991) and reduced toward early

summer (June 1991) (Figure 21). This figure also shows the changes of SS load

in the influent. There is a good correspondence between the number of species

and the SS load changes. In the microanimals in the biofilms, if we consider

SS as a food source for the organisms, such correspondence between SS and the

number of species may be illustrated by niche expansion because of the food

(quantity and quality) supply. Further, the number of species in each organism group is similar to each other despite different sampling unit. The maximum difference is 16 in January observation.

S

1.2 L

0

0a

S S8

W;.•l• Jan. 1991 Her. 1991 hmo MI "ronth

-Microanimals - - -i- - - Microplants ............ Zooplanktons *--- Phytoplanktons

- -SS load

Figure 21. Seasonal changes of the microorganisms in

the channel and SS load in the influent

The following relationships among the number of species, the number of

individuals, and the dry weight of the biofilm are obtained.

A. The relationship between the number of species and individuals are

seen to be below a certain level. Thus, their relationship is confined to the shadowed area in Figure 22.

b. The relationship between the dry weight and the number of individuals is seen to be below a certain level. Thus, their relationship

is confined to the shadowed area in Figure 23. The maximum number

of individuals present in the area may be below 600 mg/l00 cm2 of

DW. In the area above 600 mg/100 cm2, the number of individuals may

be below 500/cm2 .

239
low IMa

1 4 14M

n

d

i I -1 I1u V | N

d d u 1I1 £ I•3

2 2

Figure 22. Relationship between Figure 23. Relationship between

the number of species the dry weight of the

and individuals of biofilm and the numthe microanimals in ber of individuals

the biofilm of the microanimals

in the biofilm

9. The number of species increases with dry weight up to 600 g/100 cmZ,

but it is maintained at 10-12 species afterwards (Figure 24).

Some speculations can be made from the above relationships. There is a

carrying capacity corresponding to a particular number of species. The number

of individuals is maintained below that level of carrying capacity. The number of species and individuals is dependent on the space (represented by the

dry weight) below a certain level, but both are independent of the dry weight

above that level. That is, if-the microorganisms in this experimental channel

are contributing to purification, surplus biofilm over 600 mg/lO0 cm2 may contribute to the clogging of the channel or humus production. By the way, the

removal efficiencies of the channels which have over 600-mg/100 cm2 biofilm

(No. 3 in Jan. 1991; No. 2 and 3 in Mar. 1991; and No. 2 in June 1991) are

relatively low, although there are some exceptions (Figure 8).

The relationship between the number of species and the population density (N/%•.-.yweight mg/cm 2) is expressed next (Figure 25). It seems that there

are three kinds of relationships. That is, group-A in the figure has a proportional relationship; the density is keeping below a certain density level

in group-B; and group-C is a special case consisting of only two species. In

group-A, the proportion of the primary dominant species is higher than 60 percent. The number of microanimal species is also affected by the dominance

proportion of the primary dominant species (Figure 26). Thus, the number of

species in the biofilm declines with the dominance proportion.

240
a.

U

'4 U

U U

byNo

dr •fwegh of th 

the bioil

S

IS U

* U

* U..

~ N0

Figure 24. Relationship between the

dry weight of the biofil.

and the number of species

of the microanimals in

the biofll.

US

3-U- do-;

Ila.I a

Figre25 Rlaioshp bewe h

numbe of sec ies n h

* I

Figure 2 populationhp denstyeen/dhe

weight mg/cm2)

241
14

12'

$

% ofS Swis

an the nube of spce nth i

4'

am e e em • t Im

Sor 1t swIm

Figure 26. Relationships between the proportion of dominance

of the primary dominant microanimal species in the biofilm

and the number of species in the biofilm

Figure 27 illustrates the pattern of succession of the dominant species

found in the biofilms. In case of microanimals (Figure 27A), the freshwater

species, Carchesium, Vorticella and ZoothamnLum, have been mostly dominant one

after another. Marine Ciliata like EutintInnus and TIntlnnopsls increased in

March 1991, though their dominance proportion was low. Further, the metazoans

(Nematoda, Monosytla) have maintained constant but low proportion through the

whole experimental period. On the other hand, alternation of the primary

dominant species seen in the microanimals is not recognized in the microalgae

in the biofilm (Figure 27B). Although Aphanothece occupied an overall majority in November 1990, only Skeletonema costatum is the primary dominant species after that.

Comparisons with biological aspects in the wastewater treatment plant

will be discussed as follows. It is however, necessary to pay attention to

the interpretation, because there is a great difference between seawater and

freshwater.

We may know some of the purificatory conditions in the present experimental channel from the biofilm. In the condition when the proper pollutant

load is supplied sand the purification is proceeding smoothly, such Cilita as

Carcheslum, Zoothamnium, Eplstylls, Opercularia, etc., are dominantly present

in the biofilm in the wastewater plant (Kuniyasu 1988, Sudo, ed. 1988). Among

them, Zoothamnlum and Carchesium also dominantly appeared in the present

channels.

The color of the biofilm is also a good index for the degree of the

proper pollutant load. In the wastewater, gray-brownish biofilm indicates

proper load, and brownish biofilm shows a rather small load (Inamori 1989).

In our observations, the color of the biofilm is generally brownish. By the

way, mean pollutant load of T-COD in the whole experimental period was

0.9 g/m2/day and that of T-TOC was 1.11 g/m2/day.

Role of micrometazoans in water purification and sludge reduction has

been repeatedly emphasized (Inamori 1989; Inamori et al. 1987, 1989; Sudo,

ed., 1988), because clogging of the channel is the most troublesome problem in

the maintenance of channel-type facilities, and there is no effective sludge

242
100 A

100 Carches Iu uA

Vorticella

/ Zoothanniun

50 

{Eutln

Tintinnopsis

Helicostomella

Nematode

Nov.1990 Jan.1991 Mar.1991 June 1991

10 phanot hece B

1-0 -- Skeletonema costatum

so

Na i culIa IiRhizosolenia

NI tzschla

Nov.1990 Jan.1991 Mar.1991 June 1991

Figure 27. Succession of the dominant microorganisms

in the biofilm (A: microanimals, B: microplants)

reduction method. Of the many kinds of microorganisms appearing in the biofilm, particularly micrometazoans contribute to reducing sludges. In a rich

ecosystem, a long food chain is formed because of the presence of many kinds

of organisms assigned to a variety of trophic levels, and the energy lost by

respiration becomes large. Thus, it leads to sludge reduction. The predation

by micrometazoans has primary importance for sludge reduction, because the

sludge reduction is realized mainly by the predator-prey interaction in the

food chain.

Other than those microorganisms, many kinds of sessile animals were

observed in the biofilms and pipes, and on the channel walls. Although contributions to water and sediment purification by these animals have been

repeatedly mentioned (e.g., Harris 1990; Hosomi 1989; Jorgensen 1990;

243
Kurihara, ed. 1988; Sano 1982), the mechanism of purification is scarcely

known. As for sludge reduction, for example, the snail Semisulcospira libertina contributed well to humus reduction in the porous channel, because these

snails fed on biofilms (Sano 1982). On the contrary, those sessile or benthic

animals may cause a clogging of the channel. In the present experiment, water

flow was blocked several times by the attachment of the bivalve Mytilus edulis

on the porous plate between the head pit and channel. If we grasp their purificatory function and clogging prevention methods, we will be able to develop

a new Ecological Purification Method which utilizes the biological selfpurificatory function of both biofilms and sessile and benthic animals.

The number of the coliform group is one of the important items in the

Environmental Standard on Water Pollution and the bathing suitability at beach

resorts. The number in the influent of the present experiment (13,623 MPN/

100 ml) was much higher than the standard value (1,000 MPN/IO0 ml) in level A

of the environmental standard and bathing suitability. The number in the

influent, however, decreased to 1,101 MPN/100 ml.

Chlorophyll a in the eutrophic sea, e.g. Seto Inland Sea of Japan, was

about 3.1 pg/l (1971-72) (oceanographical Society of Japan, ed. 1985). The

value in the influent of the present experiment (mean 13.2 pg/l) exceeds the

value in Seto Inland Sea. However, it was improved to 2.0 pg/l, which is

slightly lower than the value in Seto Inland Sea from 1963 to 66 when the

eutrophication had not progressed to the present level.

The relationships between the experimental conditions and the fauna and

flora, dry weight, and removal efficiencies are summarized in Table 8. The

number of individuals of microorganisms and the dry weight in the biofilm were

not affected by the gravel size, but high values of these items were obtained

in the channel with rapid flow velocity. Aeration affected the number of

individuals of zooplankton, and high values were shown in the aerated channel.

The reason for this tendency may be the survival of the organisms due to the

presence of enough oxygen to survive. The relationship between the gravel

size to flow velocity and the removal efficiency of the plankton represents

the same pattern as the case of SS. Meantime, the adverse effect on the

removal efficiency of zooplankton by aeration is found. The reason for this

tendency may be the survival of the organisms due to enough oxygen supply. It

is necessary to strictly cut off sunlight in order to restrain the multiplication of phytoplankton in the channel.

Future Application of the Porous Bed Contact

Purification Method to the Port and Harbor Facilities

The channel-type porous bed contact purification method used in seawater

may be characterized as follows:

a. It can clarify a large quantity of polluted seawater.

b. Clogging of the channel will be delayed in the case of low pollutant load.

c. Organic matter is not so greatly removed.

d. Driving cost is cheap.

244
The channel-type porous bed contact purification method might be a very

effective purification method in harbors and canal areas in the innermost part

of a closed bay. We supposed that the channe.-type porous bed contact purification method plant is not so much a genuine purification plant as it is a

secondary treatment plant for COD removal from organic contaminated sewage

waters, because the above characteristics of the purification channel can be

adapted to meet the various conditions in such area.

How do we practically apply this channel to the port and canal area? We

propose building the channel into the harbor and marine structures as revetment, breakwater, etc. By these means, they may have the additional function

of purifying seawater.

Some example of ideas of the built-in channel are shown in Figures 28

and 29. In the innermost part of the port with the canal network, the channel

can be inserted into the sea wall or revetment (Figure 28) or laid under the

ground. In polluted inner bays, a small area is closed by the breakwater with

the channel in its body. The pollutant seawater is purified while running

through the channel, and we will be able to use the closed area for amusement,

water leisure, etc. (Figure 29).

SUMMARY

* The channel-type porous bed contact purification method is effective

for polluted seawater as well as wastewater. It particularly has an

excellent effect on removing SS, decreasing turbidity, and improving

transparency. Therefore, the application of this method is for the

water which needs visual beauty.

* From the view point of plant maintenance and control, it is practical

to use larger gravel (in case of the present experiment 100-150 mm)

because of the difficulty of preventing clogging, although the

removal efficiency of the channel with the small gravels is larger

than that of large gravels.

9 The removal efficiency of SS decreased with flow velocity, whereas

the mass removed increased. Clogging tends to take place in the

channels with a high pollutant load per unit volume.

* Aeration is effective in the removal efficiency of COD.

0 Many kinds of organisms are observed in the channels. A new Ecological Purification Method will most likely be developed, if we aptly

utilize biological self-purificatory functions of those organisms.

9 The condition of biofilms in the present experiment resembles that in

the sewage treatment facilities in which smooth treatment is

proceeding.

* Gravel size does not affect the number of individuals of microorganisms in the biofilm and the dry weight of biofilm. However,

these values increased with flow velocity.

245
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"* The removal efficiency of planktons shows a similar tendency as that

of the SS. Aeration may adversely affect the removal efficiency,

because it enhances the survival of the planktons.

"* The number of the coliform group decreased to almost the same level

as level A of the Environmental Standard.

"* Chlorophyll a decreased to the pre-eutrophication level.

* By means of the built-in channels into the harbor and marine structures, they can have the additional function of purifying seawater.

LITERATURE CITED

Akiyama, M., and Matsuda, M. 1974. Higata no seibutsu kansatsu handbook.

Toyokan-shuppannsha, 322 pp. (in Japanese) (Handbook of biological observation

in tide land).

Funchakuteibutsu Kenkyu-kai ed. 1986. Fuchakuseibutsu kenkyuu-ho. Koseisha

Koseikaku, 156 pp. (in Japanese) (Method of study on the attaching animals).

Hashimoto, K., and Teranishi, Y. 1988. Ryuuronai fuchaku-seibutsumaku ni

yoru suishitsu-jyouka no kikou. Gesuido Kyokai-shi, 25(285):41-52. (in

Japanese) (Mechanisms of water purification by micro-attached organisms).

Harris, V. A. 1990. Sessile animals of the sea shore. Chapman and Hall,

vii+379 pp.

Hashimoto, K., and Teranishi, Y. 1988. Ryuro-nai fuchakuseibutsu ni yoru

suishitsu-jyouka no kikou. Gesuido Kyokai-shi, 25(285):41-52. (in Japanese)

(Water purification mechanisms by the sessile organisms in the channel).

Hosomi, A. 1989. Murasakiigai no seitaigaku. Sankai-do, 137 pp. (in Japanese) (Ecology of Mytilus edulis).

Inamori, Y. 1989. Mizushori no tameno biotechnology koza, 28, Odei no gennryouka no biseibutsu. Yosui to Haisui, 31(4):72-73. (in Japanese) (Role of

microorganisms in sludge reduction).

Inamori, Y., Hayashi, N., and Sudo, R. 1990. Suiro ni yoru odaku-kasensui no

chokusetsu jyoka. Yosui to Haisui, 32(8):32-37. (in Japanese) (Direct purification of polluted river water by channel type of purification facility).

Inamori, Y., Kuniyasu, Y., and Sudo, R. 1987. Role of smaller metazoa in

water purification and sludge reduction. Japan. J. Water Treat. Biol.,

23(2):15-23. (in Japanese).

Inamori, Y., Ohuchiyama, T., and Sudo, R. 1989. Seibutsumaku-ho ni yoru

odaku-koshosui-jyoka ni okeru bisho-dobutsu no yakuwari. Kankyo Gijyutsu,

18(2):78-81. (in Japanese) (Role of small metazoan in water purification in

polluted lakes and ponds).

Jorgensen, C. B. 1990. Bivalve filter feeding:Hydrodynamics, bioenergetics,

physiology and ecology. Olsen and Olsen, vi+140 pp.

248
Kasen Kankyo Kenkyu-kai, ed. 1985. Kaisetsu Kasen Kankyo. Sankai-do, Tokyo.

(in Japanese) (River Environment).

Kiriku, T., Kobari, Y., and Warita, S. 1984. Tamagawa no Jyoka-jigyo.

Kankyo Kenkyu, (52):61-76. (in Japanese) (Water Purification Works in Tamagawa River).

Kuniyasu, Y. 1988. Seibutsu-shori-shisetsu no biseibutsusou to kanri, 1.

Yosui to Hisui, 30(l):75-77. (in Japanese) (Microfauna in the waste water

treatment facilities and its maintenance).

Kurihara, Y., ed. 1988. Ecology and ecotechnology in estuarine-coastal area.

Tokai University Shuppan-kai, xiii+1106 pp. (in Japanese).

Mizuno, T. 1990. Illustrations of the freshwater plankton of Japan.

Hoikusha Publishing Co., Ltd., vii+8+353 pp.

Oceanographical Society of Japan, ed. 1985. Coastal oceanography of Japan

Islands. Tokai University Shuppan-kai, viii+8+353 pp. (in Japanese).

Otsuki, T. 1990. Jinko lagoon. Umetate to Shunsetsu, (152):10-17. (in

Japanese) (Artificial lagoon).

Sano, K. 1982. Suisan Yoshoku to Mizu. Scientist sha, ix+244 pp. (Aquaculture and water).

Sea Blue Technology Association. 1989. Sea Blue Plan. vii+239 pp. (in

Japanese).

Shiino, S. 1969. Suisan musekitsui doubutsugaku. Baifukan, viii+345 pp. (in

Japanese) (Biology of invertebrates).

Sekiyama, K., Nakazato, M., and Yamaguchi, T. 1987. Toshi-gesuiro zappaisui

taisaku-jigyo ni tsuite. Gesuido Kyokaishi, 24(273):79-87. (in Japanese)

(Measures against waste waters in the metropolitan area).

Sudo, R., ed. 1988. Biseibutsu-koteika-ho ni yoru haisui-shori. Sangyo

Yosui Chosa-kai, Tokyo, 284 pp. (in Japanese) (Waste water treatment by

microorganisms).

Sudo, R., ed. 1989. Kankyo-jyoka no tameno biseibutsu-gaku. Kodansha Scientific, Tokyo, viii+221 pp. (in Japanese) (Microbiology for the environmental

purification).

Sudo, R., and Inamori, Y. 1989. Zusetsu, Seibutsuso kara mita shorikino no

shindan. Sangyo Yosui Chosa-kai, Tokyo, 287 pp. (in Japanese) (Illustration,

Diagnosis of purification process by microfauna).

Tazawa, R., Sato, H., Shimizu, K., and Kashiuchi, T. 1991. Rekikan seibutsu

shori ni yoru heisasei kaiiki no suishitsu, dakushitsu no kaiazen ni kannsuru

ichi kasatsu. Nihon Engan Kaigi kennkyutoronkai koen gaiyo-shu, (4):18-19.

(in Japanese) (Study on the purification in the closed sea area by porous bed

contact purification method).

249
Tsuchiya, J., and Izumi, K. 1983. The river purification by catalytic oxidation method on the stones 1. Ann. Rept. I. C. E. of TMG, 1983:115-130. (in

Japanese).

Tsuchiya, J., and Isumi, K. 1984. Water quality self-purifying function by catalytic oxidation method of ascending current on the stones 1. Ann. Rept.

I. C. E. of TMG, 1984:133-141. (in Japanese).

Tsuda, M. 1982. Ecology of water pollution. Kogai Taisaku Gijutsu Doyukai,

Tokyo, vi+240 pp. (in Japanese).

Yamada, T., ed. 1983. Seibutsugaku jiten 3rd ed. Iwanami Shoten, 1404+349

pp. (in Japanese) (Biological dictionary).

250
STABILIZING METHOD BY SOLIDIFICATION FOR DREDGED BOTTOM SEDIMENTS

Nobuaki Wads

Japan Sediments Management Association

Tokyo, Japan

ABSTRACT

It is possible to utilize the dredged seabed

sediment effectively as excellent material after the

proper treatment. Main purpose of the treatment is to

eliminate harmful substances and to satisfy the technical requirement from a viewpoint of civil engineering. This paper introduces the solidification

technique as a treatment method and usage of its chemical improvement effect. Merits of this technique are

mentioned below: 1. Filling can be done on the

reclaimed land with sediment. 2. Structures constructed on the sediment will be stable by in situ

treating of the sediment. 3. Treated sediment can be

used effectively for civil engineering purposes.

INTRODUCTION

According to the recent remarkable development into urbanization, suspended sediments have been accumulated at bottom of rivers, lakes, coves, and

bays. These bottom sediments cause serious environmental problems. Usually

this problem is solved by dredging the bottom sediment and transporting to a

disposal area provided in advance. However, in Japan, it becomes harder to

provide the new disposal area.

In this regard, stabilizing the dredged sediments for the purpose of

effective use has been recently required as one of the solutions to solve the

above situation. The Japan Sediments Management Association has been studying

the stabilizing system and method which is shown in Figure 1.

In this paper, typical properties of bottom sediments in Japan are

explained first; then the dredging of bottom sediments for the purpose of

water clarification is outlined; and finally the recent trend of sediment

stabilization by solidification for the effective use is reported.

TYPICAL PROPERTIES OF BOTTOM SEDIMENTS

Bottom sediment (conventionally called "HEDORO" in Japan) is generally

defined as the sediment composed of particles that originated in natural or

artificial activities and gradually settled on the bottom of lakes, rivers,

and seacoast. There are commonly a few typical properties in the bottom sediments in Jipan as the following:

251
Field drallaie

-mecmamicai DehYdraliom

eThis Layer fredgiag

.111gh Density Dredging

-Field SolidIrlcAtIOb

Figure 1. Flow chart of sediment stabilization

A. Very high water content. Water contents of the bottom sediments are

mostly 150 percent through 250 percent at the essential part and are

often 400 percent through 500 percent at the surface layer. As

shown in Figure 2, wet density duly increases as water content

increases.

I. Very loose at surface layer. As distributions of water content and

wet density at each depth are shown in Figure 3, the 20- through

30-cm-thick layer from the surface deposits in a particularly loose

condition. Bottom sediment has little sand in grain distribution

and is tLmost full of silt and clay.

c. High organic content. Organic content is generally identified by

ignition loss. As shown in Figure 4, chemical oxygen demand (COD)

value is reported to be linearly proportional to ignition loss.

•. Bad odor. Organic matters are decomposed anaerobically by the

action of bacteria, and then they are changed into sulfate gas such

as hydrogen sulfate and mercaptan. Among such badly smelled odorants, hydrogen sulfate gas is generally more uncomfortable. An

example of measurement of the generated gas and sulfate content in

the bottom sediment at a canal in Japan is shown in Figure 5, and

medical influences on human body by two kinds of gas are shown in

Table 1.

j. Heay metal content with high RossIbility of dissolving into water.

According to a report, the tendency shown in Table 2 considered that

most of the bottom sediments commonly contain some heavy metals even

252
2.0 - - Wet Density p, (t/ 23)

1.9 i 1.1 1.4 I.T

0 v sea-bott

,--- - -8 - o1 .5 ..1.7 ;. .- I \.,,

1 .4 -

.3 - Vr %- - _ _

1.2.1 . : .. :... :....4-.'- a

I~o"

0 100 200 300 400 500 600 400 700

Natural Water Content ws MI Water Content ws (9)

Figure 2. Relationship between Figure 3. Typical distrinatural water content bution of water

and wet density content and wet

density at bottom

sediment

4~ t.

!00 --- -

50-

0 /

10 20 30 40 50

1g. Loss (S) ' la' ' " ""

Figure 4. Relationship Figure 5. Relationship

between igni- between sultion loss fate content

and COD and genierated

gas

though chemicals and the quantities contained differ from each

other. The dissolved quantities of toxic materials out of the

sediment that go into water are legally regulated by the government of Japan. Therefore, the quantities must be strictly controlled to be less than the regulated values on the disposal and

stabilization of bottom sediments. The regulated values are shown

in Table 3.

253
TABLE 1. MEDICAL INFLUENCE OF HZS GAS AND NH3 GAS ON HUMANmS BODY

Hydrogmen Sulfate (HIS) Gas Aaonia (NN.) Gas

Density InfLuence DoemtIY Influence

70-110 0.1-0.15 Some influence after 53 0.035 To be able to

I Long time catch melt

100-150 0.14-0.21 InfLuence after several 85 0.06 To be abte to

hours beer for 6 hours

without reiark-

_abe poisoning

170-260 0.24-0.36 To be able to bear for 100 0.07 To be poisoned

0.5 - 1.0 hour without after many hours

poisoning work

360-500 0.5-0.7 To be dangerous after 300-500 0.2-0.35 To be abte to

breathing for 0.5 - 1.0 bear for 0.5 -

hour 1.0 hour work

420-600 0.6 To be dead soon or 408 0.3 To be clearly

tater after breathing staijLattve

for 0.5 - 1.0 hour

850-1000 1.2-2.8 Instantaneous death 698 0.5 To be stimuLative

on throat with

cough

1000-3000 1.44.2 Instantaneous death 1620 1.2 To be stimutative

on throat with

___________ _____________________ _________ cough

2150-3900 1.5-2.7 To be dead soon

after breathing

for 0.5 - 1.0

hour

36006500 2.5 -4.5 Death within 0.5 - 1.0 hour

5000-10,000 3.5 -7.0 mostty Instantaneous death

f. Many kinds of rubbish in sediments. Depending on the situation and

their background, the bottom sediments are mingled with various

kinds and sizes of rubbish, such as garbages, metal scraps, dungs,

trashes of paper, textile, rubber, constructional wastes, carcasses,

plastics, waste oil, and other dusts.

The general properties of bottom sediments just explained above, showed

much variety even at the same place. In this regard, survey and investigation

of bottom sediment must be multi-itemized.

EXAMPLE OF WATER CLARIFICATION BY DREDGING WORK

The result of water clarification by dredging bottom sediment at the

lake is analyzed by Japan Sediments Management Association (1991) and is

reported here. Newspapers in Japan stated that: "Once COD value, as an index

of current environmental evaluation, was 12 mg/l in annual average between

1980 and 1981. The value was listed on the worst environmental rank out of

all lakes in Japan for two years cc 'ously. But COD in 1990 has recorded

the minimum value indicating 6.3 mE the inlet of the lake and 7.7 mg/l at

254
TABLE 2. EXAMPLES OF HEAVY METAL CONTENT IN BOTTOM SEDIMENTS

Way of InLand Coastal Specified AnaLysis Disposal Reclemstion Off-shore Abandornmnt Rectmtion Method etc.

Kind of (1) Slag (1) Organic (1) Bottom Method List

Waste (2) Non-soLubLe sediment sedi- of

inorganic (2) SoLtubLe mant Identisediment inorganic etc. fication

(3) Incinerated sediment (2) Ses-bed

sediment sol t

including Hg ReguLated Regutated VaLue ReguLated VaLue Value

Toxic (Dissotvient (D0ssotvement ReguLated VaLue (DisolveSuibstance Test) Test) (Content Test) ment Test)

Atkylic- ND ND ND ND JEA Notice 0.0005

fig No. 64

Hg <0.005mg/C 0.005 mg/C <2 mg/C <0.005mg/t ditto 0.0005

Cd <0.3 mg/C 40.1 mg/t <5 mg/C (0.1 mg/C JIS K-0102 0.05

Pb <3 mg/C <1 mg/C <50 mg/C <1 mg/C JIS K-0102 1

Organic-P <1 mg/t <1 mg/C 5 Wm/t _ 1 mg/t JIS K-0102 --

Cr. 01.5 mg/C <0.5 mg/C <25 mg/C <0.5 mg/C JAS K-0102 0.04

As 01.5 mg/C <0.5 mg/C <25 mg/C f0.5 mg/C JIS K-0102 0.4

CN <1 mg/C <1 mg/t <5 mo/C <1 mg/C JAS K-0102 0.01

PCs 40.003 mg/C <0.003 mg/C <0.15 mg/t <0.003 mg/C JEA Notice

I I_ No. 59

Organic- <40 mg/e, <40 .j/C't " JEA Notice

CL I No. 13

the outlet. These values are evaluated to be on the way of environmental

improvement in the long term aspect."

Proposed Plan for Water Clarification of the Lake

Depending he target of water clarification at the lake which was set

on List "B" regw zg COD value at 5 mg/l, the dredged thickness of the lakebed ranging 80 h de was proposed as shown in Table 4, which was based on

the distribution of the contents of more than five environmental substances by

the vertical sampling of bottom sediment at many points in the lake. After

all, the total volume of the bottom sediment to be removed at the lake was

assumed to be 1.6 x 106 m3 .

Effect of Water Clarification by Dredging

The accumulated volume of dredged soil at the lake from 1977 to 1990 has

amounted to 350 x 103 m3 out of 1.6 x 106 M3 planned for dredging. COD values,

as index of water clarification, have been measured every year in Figure 6

since 1976 when dredging work started. Water clarification has been attained

about 35 percent of the time on the basis of recent COD values.

Meanwhile, according to "Theory of Peak Value in Summer Season" the

dissolved substances out of bottom sediment are most activated in summer.

Consequently, the number of plankton extraordinarily increases, and the

255
TABLE 3. LEGALLY REGULATED VALUE OF TOXIC SUBSTANCES

PLace -eavy Netal content (N/kg-dry wt.) COD

Thick- (No-/

Hark ness 1 Origin T-HO I1-Mg Cd Pb O-P Cr" As CI Pc3 t)

R-1 River 1-2 Urban 1.9 ND 38 530 ND ND 48 ND 15 100

-wste

R-2 * 0.5-1 Leather 0.18 ND 0.6 58 ND 1.4 74 1.1 0.01 222

factory

I-3 * 2-3 Chemi- 100-500 ND ND 72 No ND 30 ND MD 44

cat

factory

L-1 Lake 1 House- -- ND ND 100

hold

waste

L-2 * 0.7-1 House . - -- 2.4 19 .. .. .. ND ND 41

hold

waste

L-3 6 0.3- House- 0.3 ND 1.3 50 ND ND 10 ND ND 50

1.1 hold

waste

S-1 Harbor 0.3-4 Cheani- 100-500 -- 1.6 250 ND 0.06 86 NO No 40

cat

factory

s-2 N 1.5 Paper 0.3 ND 1 20 ND NO 6 ND ND 225

mitl

factory

S-3 - 3 Paper 0.1 -- 0.3 .. .. .. .. .. 5-63 150

miLL

Ifactory

TABLE 4. THICKNESS OF BOTTOM SEDIMENT TO BE REMOVED

Environmental Specified Value Thickness to be

Substance to be Removed Removed

Lake-bed Ignition Loss 16. 5% 69 cm

Sediment & Soil

(Less than 15% of C 0 D 100 mg/g 80 cm

Organic Content) T - C 70 mg/g 61 cm

Sulfate Content 1 mg/g 63 cm

Specification for Dissolving Rate 2 mg/m 2/day 75 cm

Water Clarifica- of Phosphorus

tion

Thickness of Dredged Lake-bed (Final Decision) 70 cm

background value of total phosphorus (T-P) duly increases. Therefore, minimizing the increase of COD background value increases water clarification. In

this regard, monthly changes of T-P values in 1980-1981 and 1989 are comparatively shown in Figure 7.

256
LI.

L-P t % Average of IM 9 I NI I *'

0 -. A

I I I -,n %Z zlae-IE

L 0. 1_1914

o 'S,1'f/ . FA... FJ'

•r J u a1. .... i, ,

so k/-f * .- 4 S 6 7 n 9 10 11 12 1 Oear iNOet

kfing started

Figure 6. Yearly changes of COD of Figure 7. Monthly changes of T-P

of the lake water of the lake water

As mentioned in this chapter, dredging of bottom sediments has greatly

removed COD, T-P, total nitrogen (T-N), etc., which are the main factors

against water clarification. Furthermore, keeping the waterdepth (or seadepth) helps to improve biological environment.

SEDIMENT SOLIDIFICATION METHOD

Dredging bottom sediments is generally effective on water clarification

as reported in the previous chapter. However, in Japan disposal areas for

dredged sediments have become smaller in number and narrower in each area.

The sediment solidification method in this chapter is one of the stabilizations which were researched and studied at Japan Sediments Management Association in order to solve limitation of disposal areas.

Tvnical Pronerties of Solidification Sediments

£. Change from soft muddy state to rigid.. The mechanism of chemical

reaction on sediment solidification is generally explained in Figure 8. Table 5 shows a test result of sediment solidification.

SCeuentltious 10 lyrain: I lydrated Products Pozzolanic C* Solidified

Material 4 Clay Minerals Reaction Sail

Figure 8. Principle of solidification method

257
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k. Addition of more cement to or anic sediment for solidification.

Organic matters in bottom sediment is the greatest obstacle for

hydration and pozzolanic reaction. Figure 9 shows an example of a

solidification test which shows organic matter as a substantial

obstacle. At this test, normal portland cement was used. Curves in

Figure 9 clearly decrease while ignition loss as an index of organic

matter increases.

Sia

I-\

C/2 4 - - -

6IX

1-. Loss (

Figure 9. Relationship between ignition loss and compressive strength

•.Effectiveness on bad odor, On the process of solidification by

cement, calcium in cement and hydrogen sulfate (H2S) gas in bottom

sediment are combined easily under alkalic, condition (pH-12), and

then H2S gas, which is the main origin of bad odor, disappears for

the new production of calcium sulfate. The following is an example

of bottom sediment solidification at Tago-no-ura where H2S gas was

remarkably generated.

(1) Leaving 15 min after mixing 100 g of quick lime (CaO) with

10 kg of bottom sediment at Tago-no-ura for 5 min by using

rotary mixer (50 rpm), the odor of H2S gas has completely disappeared, and the typical dark brown color of raw sediment also

disappeared with separation of clear water from the sediment.

Assuming 1,000 ppm of H2S gas is generated from 1 m 3 of sediment, the required mixing ratio of CaO is calculated to be

1.96 g/M3 by using the formula:

Wc -Vg * rg Rwhere

Wc - required mixing ratio of CaO (g/m3)

Vg - mole number of H2S gas generated from I m 3 of sediment

rg - mole weight of H2S gas

R - (CaO/H2S) - 1. 64

259
(2) If pH value of sediment indicates alkali, amonium salt contained in the sediment is dissolved into stimulus ammonia (NH3)

gas. In this case, the deodorization of NH3 gas can be temporarily attained by spreading some acid on the sediment for

neutralization.

•. Effectiveness on fixation of toxic substances. When a solution

becomes alkali, metal (M') ion in the solution and excess (OH) ion

chemically react (M + OH - MOH) and produce a deposit of oxygenhydrate (MOH). This MOH is so hard to dissolve into the solution that

the density of (M) ion enormously decreases. The fixation effect of

toxic substances by solidification is based on the above mechanism.

Figure 10 shows a test result of lime-mixing stabilization by

Bechtel Company for the purpose of removing the heavy metals.

I00-

SD -,

U

Ac M d Q O C m 11Cl Ma. N1I% &b 7

Figure 10. Effect of removing heavy metal ion

Sediment Solidification Methods

Sediment solidification methods are basically classified into two methods: (a) In Situ Solidification, and (b) Solidification at Temporary Disposal

Area.

In Situ Solidification Method

In Situ solidification method is to solidify directly bottom sediment at

the original seabed (riverbed or lakebed) or to solidify dredged sediment at

permanent reclaimed land. Currently, methods illustrated in Table 6 are

applied to many projects. Objectives of in situ solidification are:

p. Trafficability of construction machines by surface solidification,

and land creation by sand capping on the solidified rigid layer.

b. Utilization for construction materials by full solidification.

g. Stabilization of foundation for the structures by solidification.

Solidification at Temporary Disposal Area

This type of solidification is to solidify dredged sediment at temporary

disposal area and then to transport to a permanent disposal area. Table 7

shows three methods currently applied. Objectives of this type are:

260
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aEI4 JO q2)Ss.,1tJa4O *IIt2IJ!34IliJaiqi )uIJIPII'

261
TABLE 7. SOLIDIFICATION METHOD AT TEMPORARY DISPOSAL AREA

Mixing Plant Type in-line Mixin Type Field Mixing Type (ex. Mthnd) -JDIX (ex. KH Mixint Method) (ex. Rotary Operation Type)

Dredger Mixing Plant Dredged Sediment

reteria , --- Iiteria l[___eMaterial

I elvery In-line Mixer -Pump .... .....

CuringPit [LiZ C gCuring Pit

a Capacity :25m'/h.5mm'/hloQm/li Capacity :3oin'/h, iSom'/h Capacity : o30mv/h

Material : Powder Material : Powder Material : Slurry or Powder

SDepth of Pit : Max.30m Depth of Pit : Max.30w Depth of Pit : Max.20m

A. To make easy handling for transportation to a final disposal area

and/or for earth works there.

k. To make effective use with required properties by solidification.

Required function for Effective Use

At the planning stage of effective use of solidification sediments,

there are dully different kinds of required functions which may be classified

into mechanical function and environmental function.

Mechanical Required Function

a. Example-l. To transport dredged bottom sediment to the permanent

disposal area without spilling out of vehicles.

Unconfined compressive strength of solidified soil can be generally

evaluated for transportation.

qu > 0.3 kgf/cm2 : easy for transportation

qu - 0.05 - 0.3 kgf/cm2 : depending on the properties and

condition of transportation

qu < 0.05 kgf/c 2 : very difficult for

transportation

The required value of unconfined compressive strength of solidified

sediment is qu - 0.5 - 1.0 kgf/cm2 in many cases because of the

variety of raw properties.

b. Example-2. To have trafficability on disposal area for construction

machine,

Table 8 shows required cone index of the ground for the trafficability of construction machines in general. Therefore, required

262
TABLE 8. NECESSARY CONE INDEX FOR TRAFFICABILITY

Machine for Earth Work Required Cone

Index qc (kgf/cm2 )

Bulldozer (Very soft ground type) > 2

Bulldozer (Soft ground type) > 3

Standard Bulldozer (Middle size) > 5

Standard Bulldozer (Larger type) > 7

Scrape-dozer > 6

Scrape (Pulled type) > 7

Motor-scraper > 10

Dump-truck > 12

compressive strength of solidification sediment shall be enough to

be qu - 0.5 - 1.0 kgf/cm2 .

c. Example-3. To reuse for construction materials.

As strength of solidified soil increases with the time, the plastic

behavior at an early stage changes to the rigid behavior, as shown

conceptually in Figure 11. This figure shows that the solidified

soil "C" has a clear peak in its strength at a comparatively low

strain condition.

/

'Soi

,So0lidified Soil

kgl

ca7

,//Sandy Soil

6

ra Soft Clay Soil

-" Strain (W)

Figure 11. Behavior of soil

The mechanical behavior is considered to be identified with the

modulus of deformation E5 0 . Table 9 gives standard values of the

modulus of deformation E50 for several kinds of construction materials. This table may be applied to the case on effective use of

solidified soil or sediment.

263
TABLE 9. MODULUS OF DEFORMATION FOR CONSTRUCTION MATERIALS

Material Modulus of Deformation Test Method

E50 (kgf/cm2 )

Soil -100- by CVT Test

Sand 100-500

Mixture of Gravel 500-2,000

Sand & Clay

Crushed Stone 500-2,000

Soil Cement 10,000

2 Pit Sand 500 by Plate Loading

Test at Test Crusher-run 1,000 Pavement

Grain Controlled 1,000

Crushed Stone

Soil Cement 15,000

Lean Concrete 40,000

Macadam 2,500

Slag 1,000

3 Grain Controlled 3,000 by Plate Loading

Crushed Stone Test at Actual " ~Road

Crusher-run 1,100

Sand 350

4 Soft Clay 5-40 for Foundation

Normal Clay 40-80 Design of Pile

Loose Sand 80-150

Stiff Sand 100-200

Dense Sand 500-800

Dense Gravel & 1,100-2,000

Sand

Environmental Reauired Function

As the effect of preventing the dissolvement of heavy metals and the

effect of the deodorization are explained in the section, Typical Properties

of Solidified Sediment, the research and study, which were carried out by

Japan Sediments Management Association, are reported here.

264
Test results of the bottom sediment sampled at the lake are shown in

Tables 10 and 11. The purpose was to study the environmental impact on underground water when the bottom sediment was solidified and then reclaimed at the

disposal area.

A. Specification of solidification. At first, volumetric ratio of

dredged sediment and pit sand were 20 and 40 percent and then

125 kg/M 3 of cementitious material was added. Finally test pieces

were made for 28-day compressive strength after mixing the above

three. The pit sand has the following properties:

Grain Distribution : Sand 92 percent, Silt & Clay 8 percent

Specific Gravity : 2.708, Water Content 6.1 percent

pH : 6.4, Ignition Loss 1.5 percent

TABLE 10. TEST RESULT OF BOTTOMS SEDIMENT AND

SUBSOIL AT THE LAKE

Sample Sediment (A) Sediment (B) Sediment (C)

Test Item

Grain Gravel(2000pm-)% 0 0 0

Distribution

Sand(74 -200 0 t- 5 2 1

Silt (5-75 pm) % 62 63 60

Clay ( - 5 pm) % 33 35 39

Max. Grain Size 0.42 0.42 0.25

Consistency Liquid Limit wL 126.0 129.0 350.6

Plastic Limit w. 57.8 62.8 81.5

Plastic Index Ip 68.2 66.2 75.6

JIS Classification (MH) (MH) (MH)

Specific Gravity G3 2.426 2.510 2.454

Natural Water Content w 226.3 238.3 350.6

Condition %

Wet Density pt 1.217 1.214 1.150

g/cm

3

pH 5.8 5.8 5.9

Ig. Loss % 12.6 11.8 13.5

265
TABLE 11. CHEMICAL PROPERTIES

Test Item A B C

pH 5.8 5.8 5.9

1g. Loss 12.6 11.8 13.5

COD mg/g 43.0 41.4 69.5

Sulfate Content mg/g 0.85 0.72 1.17

T-N mg/g 3.29 3.03 4.44

T-P mg/g 4.55 4.38 4.80

T-Fe % 9.1 9.4 8.1

T-Mn mg/kg 1200 1100 1100

ORP -80 -90 -50

Conductivity (ps/cm) 320 307 384

Cd mg/kg 1.1 0.98 0.94

Cu mg/kg 86 81 77

Zn mg/kg 510 490 480

As mg/kg 19.7 16.3 12.8

b. Method of dissolvement test. The 20-day dissolvement test was carried out by using the apparatus shown in Figure 12. Following dissolvements were measured at the test.

(1) Dissolved quantity out of raw sediments "A" and "B".

(2) Dissolved quantity out of solidified sediment mixed with

pit sand by 20 and 40 percent volumetric ratios.

c. Result of dissolvement test, Result of dissolvement test on raw

sediments ("A" & "B") and solidified sediments (20 and 40 percent

mixing ratios) are shown in Table 12 with the legally regulated

values in Japan.

d. Consideration on the result.

(1) Whether the sediment was solidified or not, there is some possibility the regulated values of organic substances might be

exceeded. However, the sediment has no problem unless the

water at the lake is greatly discharged into the river which

may be intaken for drinking water.

(2) The environmental impact on underground water can be neglected

since dissolved quantities of heavy metal cleared the regulated

values by solidification.

266
,.,Pinch valve(l) F r

Original ---

Water Level

Test d Sedim "//LL - -e- 1.l. ,eI- Pinch valve(2)

"D -''Sampling Bottle

Solidified Solidified Raw-Sediments

(20%) (40%) (A & C)

Figure 12. Dissolvement test apparatus

APPLICATION OF SOLIDIFICATION METHOD

Application of two types of solidification methods are introduced here.

In Situ Solidification Method

The large scale in situ solidification test were conducted at the disposal area shown in Figure 13.

Owner : Public Cooperative of Tokyo Port Wharf

Project Name : The Shallow Solidification Work for the Extension of

Off-Haneda Disposal Area

Three areas, 4-2B, 3-2B, and 3-1B, were already reclaimed with dredged

soil and shouald be entirely covered with excavated soil for the use as a part

of Haneda Airport. However, the dredged soil had such a high water content

and a high organic content that filling work for whole areas was quite impossible. Therefore, the shallow solidification method was applied to create a

rigid surface layer where the filling work could then be carried out. Figure 14 shows the overall work flow of new land creation on the reclamation

area of dredged soil.

267
V V V

V V

1' ZV

GigZv

-a c

VV V V

ii - ; F

CD- - en W)

VVV VV v

V V VvV VV ZV z v v

Iva--

o~ ci

* - rs! -

V~C.,-C

C-i)'

V n V V C, o.- 

V V ~ .

-I IK I-

- ~ a zn A __. 

I l wl~lz z r.. I-I
Lii.i 2 - 2-

Disposal Area

for Dredged Soil

Figure 13. Location of dredged soil reclaimed disposal areas

Reclaimed with Solidi fication Work Fill ing Work with

Dredged Soil " for Rigid Layer Excavated Soil

rii

____________________________________". .... , *,.,. 1' i olidified ;ia~l e' Slidified Layer

Water Contentdo---3oo,; I

1g. Loss ,o --- o'.

1L T.4

SOriginal SeaAbed

Figure 14. Overall work flow

For the solidification work, the lateral-operatilon type shown in Table 6

was mostly employed. Eighteen sets of machines have been employed so far. As of August 1991, the filling work at Section 3-lB had already been completed,

and that at Section 3-2B is currently being promoted.

The specification of the solidified layer follows:

Unconfined compressive strength at 28 days : qu > 2 kgf/cm2

Thickness of solidified layer : 2 m

Mixing Ratio of cementitious material : 120 kg/n 3

(Mixing ratio was decided on the test result of job mix.)

The measurement after solidification consists of the Dutch cone test (doubletube type) and the unconfined compressive strength test as shown in Figure 15.

269
eplh to tll Imfrks qc (k /cam2 )

(n) 0 1, 20 30 4050 70 OO 200300

Sot Idi , led

I .-- - -,

Layer i-, I - - -- - '-

2-

Figure 15. Test results of Dutch cone and unconfined compressive strength

Solidification Method at Temnorary Disposal Area

An example of this method of solidifying at a plant for the use of

refilling material is introduced here.

Owner : Koto Flood Cortrol Office of Tokyo Metropolitan

Government

Project Name: Double Sheet-pile Quaywall work at Sumida River

Super-Dike

Effective use of solidified dredged soil has been carried out on this project

for the purpose of refilling material onto the space between the double sheetpile quaywall. The outline of this work is shown in Figure 16.

HUDIX(50m'/ 11) Mil, Pn rant HUDIX Craw ler Crane]

I "-.. Fee'deri

Sediment Pump for Plant Vessel Delivery Pipe

Vessel Sediment

Figure 16. Outline of double sheet-pile quaywall work

A plant type mixing method (MUDIX Method) shown in Table 7 is employed

for this work. According to the report of this work, the test result of the

solidified sediments which were cured for 28 days in the wet-air condition and

in the water condition are comparatively shown in Figure 17. The result says

that the coefficient of variety in the water condition is generally smaller

than that in the wet-air condition. Such difference considered that the water

condition is rather uniform in temperature, especially in case of massive

effect. The depth of sampling and the strength of the sample are shown in

Figure 18.

270
Properties of Dredged Sediment

Water Content (M) 92.8-146.2

Wet Density 1.303-1.447

Content or

Fine Particle (M)

Shearing Strength (0.73-2.11x101) Designed Strength I kgrl/cu

(by Vane Test)

Ignition loss (%) 9.7-25.o

PI' 7.09-7.87

JIS Flow Value (m) 12o-154

1 Mixing (120 kg/s3)

ICuring in Wet Air lCuring in Water

(28 days) (28 days)

f Air Temp 20 Water Temp

=110~ 0-S"C VC i-0 

* 2. 2 (wa/n)F' T3. n MAY.0~ S =1.48 I N(lAld) @3isS =1.60 (1WAO1

V -64.6 M• ,, V-491.9 00%

a. s " s 

0 1.0 2.03.04.05.0 6.0 9 1.o0.03.04.05.06.01.0s.09.0

Figure 17. Comparison of strength in different curing condition at site

0 5 10 0 5 10 0 5 100 5 10 0 5 10 0 5 10 0 5 10 0 5 1O-Q. (kg/cmt) 1~f~1z~J1 fWFUITStr7ength 0 --- of Sample

ca 2 _Ja1±II1±nil 2~ A Sampling Depth

0 20 40 60 g8 100 120 140 160 180 2oo (ni)

Sampling Point

Figure 18. Depth of sampling and strength of sample

271
CONCLUSION

Properties of bottom sediments are remarkably scattered in many situations. Therefore, the required functions on dredged sediments for the purpose

of effective use have been duly multiclassified. In this regard, the solidification method and its technique shall be considered to be the most appropriate one for the effective use of dredged sediments in a short time. On the

other hand, the solidification method includes the matter of Ph to be solved

by some countermeasure. However, in Japan research for the effective use of

bottom sediments has been promoted by engineers from many faculties since

providing the disposal area has been becoming harder. The new technology for

this purpose shall be researched and developed with high credibility, environmental safety, and reasonable cost.

BIBLIOGRAPHY

The Japan Sediments Management Association. 1991 (Mar.). "Environmental

Investigation Report about Current Situation of River Water Clarification" (in

Japanese).

The Japan Sediments Solidification Cooperative. 1989. "Solidification System

on Very Soft Ground" (in Japanese).

Wada, N. 1991. "Surface Solidification Method," KISOKO (in Japanese),

No. 6.

272
SOLIDIFICATION/STABILIZATION TECHNOLOGY FOR REDUCING

THE MOBILITY OF HEAVY METALS IN POLLUTED SEDIMENTS

Thomas E. Myers, Daniel E. Averett, Elizabeth C. Fleming, Michael G. Channel

U.S. Army Engineer Waterways Experiment Station

3909 Halls Ferry Road

Vicksburg, Mississippi 39180-6199

ABSTRACT

Polluted sediments from four harbors in the United

States were solidified/stabilized with portland cement

in bench-scale treatability studies. The effects of

solidification/stabilization (s/s) processing on the

mobility of metals was investigated using laboratory

leach tests conducted on untreated and treated sediments. Laboratory testing showed that s/s processing

reduced the leachability of some but not all metals in

contaminated sediments. In some cases, s/s increased

the leachability of metals. The data suggest that

there is potential for mobilization as well as immobilization of metals in contaminated bottom sediments by

s/s processing. The data also suggest that the

effectiveness of metal immobilization by s/s processing is highly sediment and metal specific.

INTRODUCTION

Contaminated bottom sediments can adversely affect surface water quality

through resuspension of contaminated solids, diffusion of contaminants from

sediment pore water, bioturbation assisted release of dissolved and particulate bound contaminants, and convective flow of sediment pore water due to

groundwater gradients. Alternatives for reducing or eliminating the adverse

effects of polluted bottom sediments on surface water quality include capping

with clean sediment, removing contaminated material by dredging, and in situ

S/S.

S/S is a promising treatment technology for immobilizing contaminants in

situ bottom sediments and dredged material in confined disposal facilities.

S/S processing eliminates free water by hydration with a setting agent and

reduces contaminant mobility by altering the chemical form of contaminants

and/or microencapsulating contaminants in a cemented matrix. Setting agents

include cements, pozzolans, lime, kiln dust, and blast furnace slag. Other

additives, such as bentonite and soluble silicates, are sometimes used to

improve the physical/chemical properties of solidified/stabilized products.

We report here the metals data from laboratory leach tests conducted on

solidified/stabilized sediments prepared in bench-scale treatability studies

using portland cement. The comparison to data for leaching of metals from

untreated sediment is also discussed.

273
MATERIALS AND METHODS

Sediments

Sediments used in this study were form Indiana Harbor, Indiana; Everett

Harbor, Washington; New Bedford Harbor, Massachusetts; and Buffalo River, New

York. Figure 1 shows the site locations for these sediments. Sediment chemical characterization is presented in Table I.

Indiana Harbor is a small, highly industrialized harbor on Lake Michigan

in northwestern Indiana, approximately 10 miles southeast of Chicago, Illinois. Indiana Harbor and the Grand Calumet River which empties into Lake

Michigan through Indiana Harbor have a long history of sediment and water

quality problems. Indiana Harbor has been designated an area of concern by

the International Joint Commission (United States and Canada). The Buffalo

River which discharges into Lake Erie has also been designated an area of concern by the International Joint Commission because of sediment and water

quality problems related to industrial and municipal discharges.

New Bedford Harbor is a highly contaminated site that has been closed to

fishing and lobstering because of bioaccumulation of contaminants from sediments in the harbor. This harbor has been selected by the U.S. Environmental

Protection Agency for cleanup under the Federal Superfund cleanup program

because of hazardous posed to human health and the environment.

S.. .. : , ...... .......

3 4

t . • o ...... ... .I ...... * " ".

, • .. . .. .. . .. ...

t ------------------------------------ Z

"1 Everett Harbor, Washington

"2. Indiana Harbor, Indiana

3. Buffalo River, New York

4. New Bedford Harbor, Massachusettes

Figure 1. Location of sites used in laboratory studies

274
TABLE 1. CONCENTRATION OF METALS IN SEDIMENTS (MG/KG DRY WEIGHT)

Sediment

Metal IH* EH* NBH* BR*

Arsenic 29.5 5.7 ** **

Cadmium 20.0 3.3 35.4 **

Chromium 650 39.7 754 F6.6

Copper ** 73.4 1730 59.0

Lead 879 48.1 2013 81.0

Nickel ** 21.4 122 34.0

Zinc 4125 148 3017 151

* IH = Indiana Harbor, Indiana; EH = Everett Harbor, Washington; NBH = New

Bedford Harbor, Massachusetts; BR = Buffalo River, New York.

** Not analyzed.

Everett Harbor is located in Everett, Washington, approximately 20 miles

north of Seattle, Washington. Studies indicate that upland disposal of

dredged material from Everett Harbor could result in mobilization of metals

and adverse water quality impacts (Palermo et al. 1989).

Solidification/Stabilization Processing

Sediments were blended with portland cement in a laboratory mixer. The

ratios of portland cement to wet sediment are presented in Table 2. Interstitial water in the sediments was used to hydrate the portland cement. After

mixing for approximately 5 min, freshly prepared solidified/stabilized sediment was cured at 23 OC and 98 percent relative humidity in a curing chamber

for 28 days. After curing, solidified/stabilized specimens were crushed and

then leached as described in the next section.

Batch Leach Tests

Solidified/stabilized sediment from New Bedford Harbor, Massachusetts,

and Buffalo River, New york, was leached for metals using the sequential batch

leach test described by Myers and Zappi (1991). This procedure uses

distilled-deionized water, a four-to-one ratio of water-to-dry solids by

weight, and 24 hr of shaking time, followed by centrifugation of 0.45-M membrane filtration. The leachate is collected and preserved for chemical analysis, and the solids are then resuspended with fresh distilled-deionized water.

The shaking and separation steps are repeated for a selected number of cycles.

275
TABLE 2. CEMENT/SEDIMENT RATIOS AND SEDIMENT PHYSICAL CHARACTERISTICS

Water Grain Size Classification

Sediment CSR* Content** Sandt Silttt Clayl

Indiana Harbor 0.3 0.88 35 60 5

Buffalo River 0.2 0.73 tt tt tt

Everett Harbor 0.3 1.57 40 45 15

New Bedford 0.3 1.78 33 67 0

Harbor

* Weight of cement to weight of wet sediment.

** Weight of water to weight of dry sediment solids.

t - Percent greater than 70 Am.

- Percent less than 70 pm and greater than 2 pm.

- Percent less than 2 pm.

$- No data.

Solidified/stabilized sediment from Indiana Harbor, Indiana, and Everett

Harbor, Washington, were leached using a serial, graded leaching procedure

(Environmental Laboratory 1987). In this procedure, separate samples of

solidified/stabilized sediment are challenged with distilled-deionized water

over a range of liquid-to-solids ratios. This test is somewhat easier to

conduct than the sequential leach test because the solids being leached have

to be handled and measured only once. The serial, graded leaching procedure,

however, requires analysis of desorption isotherms in order to estimate immobilization effectiveness by S/S processing (Environmental Laboratory 1987).

Untreated sediments were leached using the sequential batch leach test

described in another paper presented at this meeting (Brannon and Myers 1991).

This procedure is essentially the same as the procedure used to leach

solidified/stabilized sediments from New Bedford Harbor and the Buffalo River

except that there is no need to crush the sediment and the test is conducted

under nitrogen to preserve the anaerobic conditions typical of bottom

sediments.

RESULTS

The mass leached from solidified/stabilized sediments was normalized

with respect to the amount of sediment that was treated by S/S processing in

order to account for dilution by addition of portland cement. In the following sections, the normalized mass leached from solidified/stabilized sediments

is compared to the mass leached from untreated sediments for various metals.

Normalized masses leached from solidified/stabilized Indiana Harbor

sediment are shown in Figure 2. As shown in Figure 2, S/S processing using

portland cement reduced the mobii -y of arsenic, cadmium, chromium, and zinc

276
1.5

\ Untreated

EL sis

CL0.5 \

As Cd Cr Pb Zn

Figure 2. Normalized contaminant mass leached from

Indiana Harbor sediment

in Indiana Harbor sediment. Leaching of arsenic and cadmium was virtually

eliminated. The mass releases of chromium and zinc, although not completely

eliminated, were substantially less than the releases from untreated sediment.

The leachability of lead was about the same from solidified/stabilized and

untreated sediment.

Normalized masses leached from solidified/stabilized Buffalo River sediment are shown in Figure 3. S/S processing using portland cement was

generally ineffective in reducing the mobility of metals in Buffalo River

sediment, as indicated in Figure 3. Although the mass releases of zinc and

lead for solidified/stabilized sediment were sightly reduced relative to

untreated sediment, the mass releases for chromium, copper, and nickel for

solidified/stabilized sediment were substantially higher than the releases for

untreated sediment.

Normalized masses leached from solidified/stabilized New Bedford Harbor

sediment are shown in Figure 4. Leaching of cadmium and lead were completely

eliminated, and the mobility of cadmium, chromium, and zinc were significantly

reduced in New Bedford Harbor sediment by S/S processing using portland cement

(Figure 4). The amounts of copper and nickel released during batch leaching,

however, were significantly higher for solidified/stabilized sediment than for

untreated sediment.

Normalized masses leached from solidified/stabilized Everett Harbor

sediment are shown in Figure 5. S/S processing using portland cement completely eliminated the release of arsenic, cadmium, copper, nickel, and zinc

in Everett Harbor sediment and indicated in Figure 5. The mass releases of

277
5

[ Untreated

3 Si

0.

Cr Cu Pb NI Zn

Figure 3. Normalized contaminant mass leached from

Buffalo River sediment

7 Untreated

6-

(1) ". 5 (D

5-

"- 4 a

0I

0L.3

2

Cd Cr Cu Pb Ni Zn

Figure 4. Normalized contaminant mass leached from

New Bedford Harbor sediment

278
10 -

_ Untreated

El s/s

~0

4)

2--

0

As Cd Cr Cu Pb Ni Zn

Figure 5. Normalized contaminant mass leached from

Everett Harbor sediment

lead and chromium, however, were greater for solidified/stabilized sediment

than for untreated sediment.

DISCUSSION

S/S is a technology for reducing the pollutant potential of contaminated

materials through alteration of physical and chemical properties. The batch

leach tests and methods of data analysis reported in this paper were designed

to provide a basis for evaluating chemical alteration of metals in sediments

by S/S processing. The leachability of some metals, such as arsenic and cadmium, was completely eliminated, and of some other metals was significantly

reduced. However, complete chemical stabilization of all metals was not

achieved for any of the four sediments tested, and in some cases, metal

mobility was enhanced.

Although portland cement was the only S/S process discussed in this

paper, the results are representative of a wide range of S/S processes. Batch

leach tests on untreated and solidified/stabilized sediments prepared using

propriety S/S processes, portland cement, and other nonproprietary processes

have shown that the chemical stabilization properties of the various processes

are very similar (Environmental Laboratory 1987; Myers and Zappi 1988; Palermo

et al. 1989; Fleming et al. 1991). The similarities include mobilization of

copper and nickel in New Bedford Harbor and Buffalo River sediments.

One important aspect of field application of S/S technology was not

addressed in the laboratory tests discussed in this paper. In the field, S/S

processing provides physical stabilization (conversion of a semisolid from a

plastic state to a solid) that reduces the accessibility of water to

279
contaminated solids. Together, physical stabilization and chemical stabilization provide two lines of defense against contaminant migration. When

chemical stabilization of contaminants by S/S processing is not 100 percent

effective, physical stabilization to reduce accessibility of water to contaminated solids can be the governing factor for water quality protection.

CONCLUSIONS

The leachability of some metals in polluted bottom sediments can be

reduced by S/S processing. However, chemical stabilization of metals in bottom sediments is rarely 100 percent effective, and in some cases, metal

mobility can be increased. The data suggest that immobilization mechanisms

for S/S processing are highly sediment and metals specific.

Reactions of S/S reagents with contaminants in bottom sediments is not

well understood, and it is, therefore, difficult to predict which sediments

and which metals are good candidates for S/S technology. Because of the

potential for misapplication, laboratory leach tests are required to evaluate

the applicability of S/S technology to sediment and dredged material.

ACKNOWLEDGEMENT

The tests described and the resulting data presented were obtained from

research conducted by the U.S. Army Engineer Waterways Experiment Station for

the U.S. Army Engineer District, Chicago; U.S. Environmental Protection

Agency, Region I; U.S. Environmental Protection Agency; Great Lakes National

Program Office; and the U.S. Army Engineer District, Seattle. Permission was

granted by the Chief of Engineers to publish this information.

REFERENCES

Brannon, J. M., and Myers, T. E. 1991. "Development of a Leaching Protocol

for Evaluating Ground Water Impact from Contaminated Sediment," paper presented at the Fifteenth U.S./Japan Experts Meeting On Management of Bottom

Sediments Containing Toxic Substances, 19-21 November 1991, San Pedro, CA.

Environmental Laboratory. 1987. "Disposal Alternatives for PCB-Contaminated

Sediments from Indiana Harbor, Indiana; Volume II," Miscellaneous Paper

EL-87-9, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Fleming, E. C., Averett, D. E., Channell, M. G., and Perry, B. D. 1991. "An

Evaluation of Solidification/Stabilization Technology for Buffalo River Sediment," Miscellaneous Paper EL-91-11, U.S. Army Engineer Waterways Experiment

Station, Vicksburg, MS.

Myers, T. E., and Zappi, M. E. 1988. "New Bedford Harbor Superfund Project,

Acushnet River Estuary Engineering Feasibility Study; Report 9, LaboratoryScale Application of Solidification/Stabilization Technology," Technical

Report EL-88-15, U.S. Army Engineer Waterways Experiment Station, Vicksburg,

MS.

280
Myers, T. Z. and Zappi, M. Z. 1991. "Laboratory Evaluation of

Stabilization/Solidification Technology for Reducing the Mobility of Heavy

Metals in New Bedford Superfund Site Sediment," in T. M. Gilliam and Wiles,

C. C. (eds.), Stabilization and Solidification of Hazardous. Radioactive, and

Mixed Wastes. 2nd volume, STP 1123, American Society for Testing and

Materials, Philadelphia, PA, pp 304-319.

Palermo, M. R., Shafer, R. A., Brannon, J. M., Myers, T. E., Truitt, C. L.,

Zappi, M. E., Skogerboe, J. G., Sturgis, T. C., Wade, R., Gunnison, D.,

Griffin, Jr., D. M., Tatem, H., Portzer, S., and Adamec, S. A. 1989. "Evaluation of Dredged Material Disposal Alternatives for U.S. Navy Homeport at

Everett, Washington," Technical Report EL-89-1, U.S. Army Engineer Waterways

Experiment Station, Vicksburg, MS.

281
REFORMING TEST ON DREDGED SEDIMENT WITH POLYMER SOLIDIFYING

AGENT AND A STUDY OF ITS EFFECTIVENESS

Kiyoshi Nikaido

Vice Chairman, Technical Committee

Sediment Management Association

5th Floor, The 15th Sankyo Bldg.

2-7-12, Tsukiji, Chuo-ku, Tokyo 104

ABSTRACT

The recent grave concern in sediment dredging is the

difficulty in finding places nearby to dispose of or

utilize the dredges. Most of such places are far and

limited in space so that the dredge has to be carried

away for disposal via an intermediate disposal area.

It is therefore desirable to compound solidifier,

particularly, a high polymer type one, with the

dredge. The present study describes the results of

experiment which applied a high polymer solidifier to

several types of dredges from the lakes an,4 swamps.

For evaluation of a cement type solidifier employing

high polymer substance, both the "spread test" and the

usual test for the cement type solidifier should be

done for comparison. The advantages of the dredge

obtained with a high polymer type solidifier are as

follows. 1) The treated soil is neutral and can be

reduced to the earth without polluting it. 2) The

volume compounded was several kgs/m3 of the dredge,

hardly increasing transportation cost. 3) The soil

has been improved to allow easy loaded consolidation/

dehydration. 4) By feeding it into a surface compression type dehydrator, the soil will reach below the

liquid limit, allowing its use for civil engineering

works.

SYNOPSIS

The recent largest problem of dredged sediment treatment is difficulty

in securing an area for final disposal or for reclamation of dredged sediment

in the vicinity of dredging site. Even if available, such an area is normally

limited in size and far from dredging site, leaving no other choice but to

process dredged sediment at an intermediate treatment site and carry it out by

dump truck, instead of direct transport from dredging site to dumping area.

However, another difficulty in providing wide space for intermediate treatment

leads to mixing the solidifying agent in dredged sediment. From the viewpoint

of soil formation with dredged sediment, demand for admixture of a polymer

solidifying agent is on the increase. This report discusses the results of

experimental application of polymer solidifying agents to the sediment samples

taken from several lakes and marshes.

282
The evaluation method of soil reforming by the cement solidifying agent

is not applicable for assessing the performance of the polymer solidifying

agent admixed in dredged sediment. Polymer solidifying agent needs an expansion test, in addition to the test for the cement solidifying agent. Results

of both tests should be compared with each other to clarify the soil reforming

effect and applicability of polymer solidifying agent.

The dredged sediment treated with polymer solidifying agent has the

advantages listed below, which will satisfy the requirements for dredged sediment treatment.

A. The dredged sediment treated with polymer solidifying agent is chemically neutral, reducible to ground soil without proliferation of

environmental pollution.

b. Admixture volume of polymer solidifying agent is several kilograms

per cubic meter of dredged sediment, hardly increasing transportation cost.

ft. Admixture of polymer solidifying agent reforms dredged sediment,

facilitating load consolidating dehydration of the sediment.

d. Mechanical dehydrator of the compressing type (face-pressing type)

dehydrates the dredged sediment treated with a polymer solidifying

agent to below liquid limit, making it possible to utilize the sediment as material for civil work.

TEST SAMPLES

As shown in Figure 1 on sludge sediment, content of water pollutants is

higher in the upper layer and decreases in the lower layer where water environment used to be well balanced. On the assumption that the pumping dredger

would perform dredging work, we prepared test samples from dredged sediment by

injecting an appropriate coagulant into muddy water of 10 percent sludge content (volume) and agitating the water before settling consolidation (Figure 2). Table 1 shows the water content of four deposit and dredged sediment

samples, FG, FR, NN, and MK, which were taken from the lakes and marshes.

The test samples were prepared as follows:

A. FG: Test samples were taken from No. 51 sampling point (0 to 60 cm

deep) by backhoe. Waste refuse and other foreign matters

contained in the samples were removed by a sieve of 4.72-mm

mesh. The samples are composed of the following two kinds:

(1) Sediment of natural water content.

(2) Sediment whose water content was adjusted by diluting

above sediment 10 times with water (10 percent sludge

content), leaving it for 24 hr to encourage sludge sedimentation, and removing supernatant water.

k. FR: Test samples, which were filtrated by a sieve of 4.72-mm mesh

to remove waste refuse and other foreign matters, are composed

of the following two kinds:

283
Water content (°),

00High water content

0.1

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S~/

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(D 0.//

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of self-purification

Figure 1. Formation of sludge sediment

(1) Ratio of sediment to lake water

= 10% to 90% (volumetric ratio) (2) Settling cylinder

= 10 cm to 90 cm

N7

ivi 0Supernatant water

Hl t

t o H t0 t I Settling sediment t 2 H t 2 1

10cm

Figure 2. Sample preparation by settling muddy water

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285
(1) Sediment of natural water content.

(2) Sediment whose water content was reduced by aerating and

drying above sediment in a room.

q. MK: Test samples, which were filtered by a sieve of 4.72-mm mesh to

remove waste refuse and other foreign matters, are composed of

the following two kinds:

(1) Sediment of natural water content.

(2) Sediment whose water content was adjusted by diluting

above sediment 10 times with water (10 percent sludge

content), leaving it for 24 hr to encourage sludge sedimentation, and removing supernatant water.

•. NN: (To be provided.)

Table 2 presents the results of tests conducted on the samples.

REACTION CHARACTERISTICS OF POLYMER SOLIDIFYING

AGENT TO SOIL PARTICLES

Polymer solidifying agent is roughly classified into a natural agent and

a synthetic agent. Both natural and synthetic polymer solidifying agents

coagulate the solids contained in dredged sediment and dehydrate the sediment,

eliminating its fluidity. As shown below the admixture of polymer solidifying

agent transforms dredged sediment and makes it possible to load treated sediment on a dump truck for transport.

Polymer solidifying agent (C103) The agent absorbs moisture and Disposal at final dumping site

coats the surface of soil particles, or effective utilization

0 *-

Soil particles for Agitation disperses the solidifying agent Coated soil particles form Major components remaining

treatment bridged nodules. in treated sediment decompose

gradually

Table 3 shows the reaction characteristics of natural and synthetic

polymer solidifying agents, respectively, against the slurry which will be

generated by the mud treatment method. The table indicates that more than

30 sec will be enough for the reaction.

286
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TABLE 3. REACTION CHARACTERISTICS OF POLYMER SOLIDIFYING AGENTS

TO SLURRY BY MUD TREATMENT METHOD

Natural Polymer Solidifying Agent Synthetic Polymer Solidifying Agent

(1) The agent is effective at mois- (1) The agent reacts to sediment in

ture absorption, requiring only a short time, requiring 1 or

30 or 60 seconds for agitation 3 minutes for agitation and

and mixture. mixture.

(2) The sediment treated with the (2) Admixture volume of the agent

agent has an appearance of ordi- is smaller compared to line and

nary crumbly soil, which is easy cement solidifying agents.

for handling. Vibration causes (3) Combined application of calcium

neither water leakage nor defor- chloride, such as slaked lime,

mation of the sediment. with the agent reforms sediment

(3) The sediment treated with the for easy handling.

agent is chemically neutral

without toxicity. The agent is

soluble and decomposes slowly,

so that the sediment becomes

harmless and safe.

(4) Combined application of cement

with the agent can adjust the

sediment at any strength.

(5) The sediment treated with the

agent loses stickiness and adhesion, so that it hardly adheres

to hopper.

TEST METHOD

Test Method of Polymer Solidifying Agent

Hydraulic solidifying agents, such as cement and lime, stabilize the

strength of sediment gradually in the course of time. On the other hand, such

function cannot be expected of polymer solidifying agent, but it combines soil

particles and forms bridged nodules, thereby reforming and stabilizing sediment. For former agents, there is already an established test method available. However, test method of the latter agent is still incomplete and under

study for development.

To evaluate the reformed condition of the sediment treated with polymer

solidifying agent, the sediment is exposed to physical vibration and its

extent of deformation (called "deformation ratio" hereinafter) is measured in

the test on the agent.

Test Procedure

Vibration test uses a table-type vibrator, whose specifications are

listed in the table below, and follows the procedure from a to d.

I. Admixture of solidifying agent, Take a sediment sample of 500-mi

volume into a mortar mixer of 2-1 capacity, and agitate the sample

288
for five minutes after injecting a specified quantity of polymer

solidifying agent.

k. Charging of agitated samle. Set a flow cone at the center of the

table-type vibrator, and charge the agitated sample (reformed sediment) into the flow cone to form two layers. Tamp each layer

15 times over the surface so that the tip of a tamping rod enters

Specification of Table-Type Vibrator (JIS 1132)

Specification Additional Tools

Model Motorized vibrator Flow cone, tamping rod,

and calipers (for the

Motor Single phase, 100 VAC flow test specified in

Amplitude 1.5 mm JI R5201)

Frequency 3000 - 3500 rpm

Table dimension 450 mm x 600 mm

Weight 250 kg

into approximately one-half depth of the layer. After tamping both

layers, fill the head space of the flow cone with additional sample

and level the top surface.

q. Measurement before test. Take out the flow cone straightly upward.

Measure the assumed maximum diameter of the formed sample and the

dimension at the right angle to the diameter by calipers. Specify

the average of the measurements as the flow value before vibration

(f.).

d. Vibration test. Switch on the table-type vibrator, and measure the

expansion of the sample at specified vibration time. Specify the

measurement as the flow value at each vibration time (ft). Calculate the deformation ratio (xil) at each vibration time from the

formula below:

xil - ft / fi

f 1 : Inner diameter of flow cone (100 mm)

Admixing Condition of

Polymer Solidifying Agent

Polymer solidifying agent is classified by material into a natural agent

and a synthetic agent. Both solidifying agents have been used for the treatment of the surplus soil discharged from construction work. The following

discusses the effectiveness of the agents in the treatment of surplus soil.

It is necessary to take note, however, that water content is in the order of

100 percent below for surplus soil, while it reaches several hundred percent

for dredged sediment.

a. Polymer solidifying agent absorbs free and interstitial water of

soil particles, and the absorption increases along with the lapse of

time. The surplus soil treated with the agent is chemically neutral

289
without proliferation of toxicity, and therefore favorable for

vegetation.

k. Use of machinery for civil and building work, such as backhoe and

biaxial kneading mixer, activates the reaction of polymer solidifying agent and reforms surplus soil within several tens of seconds or

several minutes of mixing.

ct. Though no established judgement criterion is available for transport, test results by vibrator indicate that expansion of the surplus soil treated with polymer solidifying agent is limited over a

period of time.

•. Combination of cement or lime solidifying agent with polymer agent

demonstrates synergetic effect.

Application of polymer solidifying agent to dredged sediment requires

careful study of the agent's admixing conditions.

Physical properties of the dredged sediment treated with polymer solidifying agent, such as acceptable strength for transport on dump truck, are yet

to be clarified. However, maintenance of deformation ratio (expansion) at

100 percent expansion for a long time and absence of adhering sludge on the

surface of container can be used as a guideline. To make sure of the properties, actual test at treatment site is still required.

In the reforming test on dredged sediment by polymer solidifying agent,

we conducted an unconfined compression test, which is a judgement criterion

for cement solidifying agent, to compare unconfined compression strength (qu),

in addition to the vibration test on the sediment treated with polymer agent

to clarify the properties of reformed sediment, though the results are not

discussed in this report.

Determination of Appropriate Agent and Agitation Time

To find out optimum admixing conditions, we conducted a comparison test

using a table vibrator on both natural and synthetic solidifying agents, whose

effectiveness has been proved on the treatment of surplus soil. Tables 4 to 9

show the test results.

Admixture volume of polymer solidifying agent is normally 3 or 4 kg/M 3

of dredged sediment. With an admixture volume of 4 kg/M3 , effectiveness of

the agent can be summarized as below:

j. Agitation time should be more than 120 to 300 sec to stabilize sediment's deformation ratio at 100 percent.

]. In our observation on the adhesion of treated sediment to the surface of container and others, the synthetic polymer solidifying

agent demonstrated better performance than the natural agent.

Based on the above study results, we concluded that synthetic polymer

was the optimum solidifying agent and that agitation time should be five minutes. Though "Test Method of Stabilized Treated Soil" specifies the agitation

290
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293
time to be three minutes, our test clarified that polymer solidifying agent

needed agitation for more than three minutes. We conducted reforming test on

dredged sediment after setting those conditions mentioned above.

Test Method of Cement Solidifying Agents

Cement solidifying agents are roughly classified into ordinary portland

cement and the special solidifying agent which aims at forming the soil free

from elution of harmful substances such as organic substance and metal.

Admixture volume of the agent and curing time of the mixture determine the

possibility to transport treated sediment on dump truck. The unconfined compression strength of the mixture is normally 0.5 kgf/m2 as a guideline.

We prepared samples to test cement solidifying agents in accordance with

the standard of Japan Soil Engineering Society (JSF T821 1990) specified in

"Commentary on the Procedure of Soil Tests" (Section 6- "Sample Preparation of

Stabilized Treated Soil without Compaction," Chapter 5- "Stabilization Test")

published by the Society, and measured the unconfined compression strength of

the samples in accordance with their standard (JSF T511 1990) specified in the

same (Section 1-"Uniaxial Compression Test on Soil," Chapter 7-*Shearing

Test"). Figure 3 shows the test procedure.

ISampling of sediment

Removal of waste refuse

and adjustment of water cntent

Admixture Solidifying agent Ordinary cement

Cement solidifying agent

Polymer water absorbent

CuriTngAt20

Unconfined compression test Distortion to be 1%/mm. or below.

Figure 3. Test procedure of cement solidifying agent

a. Safle. Solidified samples were crushed with knife.

b. Preparation of samile solution. Take 30 g of crushed sample (wet

sample) and put approximately 50 ml of distilled water into a clean

100-ml beaker. Loosen the crushed sample thoroughly with a clean

294
policeman to prepare a soil suspension. Leave the suspension for

more than 30 min but less than 3 hr, and use it as a sample solution

for pH measurement.

.q. DH measurement. We used a pH meter with glass electrode for pH

measurement. For the measurement of electric conductivity, we used

the solution prepared for pH measurement. Our pH measurement

conformed to "pH Measuring Method of Soil," the standard of Japan

Soil Engineering Society (T7T-1968(79)).

TEST RESULTS

Results of Reforming Test

Relation between admixture volume of solidifying agent (kg/m3 ) and

deformation ratio of sample after vibration is shown for each sample in Figure 7 (a) to (d) and Table 10 and 11 for polymer solidifying agent (C103), and

Figure 8 (a) to (d) and Table 12 (a) to (d) for cement solidifying agent.

Figure 4 below shows the comparison of four sediment samples on the admixture

volume and liquid limit which no longer cause deformation, silt and clay (%),

ignition loss, chemical oxygen demand (COD), total nitrogen (T-N) and total

phosphorus (T-P) of sulfide. The following summarizes major characteristics

of each sample.

A. FG: This sludge sediment has a high total phosphorus (T-P) and a

low true specific gravity.

k. FR: This sludge sediment contains an abnormally large quantity of

sulfide and shows a high total nitrogen (T-N). Its oxidationreduction potential (ORP) is as low as -400 mV, indicating that

it is an anaerobic sediment.

V. NN: This sludge sediment shows the least COD among the samples.

For other analytical items, this sample is not much different

from the others.

4. MK: This sludge sediment shows an oxidation-reduction potential

(ORP) of -40 mV, indicating that it is a sediment in the water

of aerobic state. For other analytical items, this sample is

not much different from the others.

Figure 5 shows the relation between admixture volume of solidifying

agent and water content of sediment, obtained from the tests on the samples

with different water content. Polymer solidifying agent shows extremely

limited ratio between the water content fluctuation and the admixture volume,

in comparison with cement solidifying agent, indicating its high adaptability

to fluctuation.

Figure 6 shows the relation between the ratio of water content of sample

to liquid limit at initial solidification and the admixture volume of solidifying agent, which stabilizes deformation ratio at 100 percent for polymer

agent and secures 0.5 kgf/cm2 third-day unconfined compression strength,

allowing for transport in dump truck for cement (special) agent. The following is a summary of analytical results.

295
(Figure not provided)

Figure 4.

E

C

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3100

0C " P I p I I I I p I

1 2 3 4 5 6 7 8 0 50 00 15020 25D M 5504D

Admixture volume of polymer solidifying agent Admixture volume of cement solidifying agent

(kg/M3 ) (kg!/M 3 )

Figure 5. Admixture volume of solidifying agent and water

content of sample (100 percent deformation ratio

for polymer solidifying agent and 0.5 kgf/cm2

third-day strength for cement solidifying agent)

296
M-35D FG

-0 .FR

Cho - O NN

i6 46 MK E

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1 1.1 1.2 1.3 1.4 15 1.6 1.7 18 19 2 2.1 22 2.3

Ratio of water content to liquid limit

8-,

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2._>. Note: At a ratio of water content on liquid limit - 0.9.

o treated sediment is possible for transport

in dump truck.

1 1.1 12 13 14 15 16 1.7 18 19 2 21 22 2.3

Ratio of water content to liquid limit

Figure 6. Ratio of water content to liquid limit

and admixture volume of solidifying agent

a. Sediment treatment becomes easier in the arrow direction. (FR)

sample is the most difficult sediment for treatment. It is because,

as discussed before, the sediment contains as large quantity of

sulfide and total nitrogen (T-N), in addition to its extremely

anaerobic property, requiring a large quantity of polymer solidifying agent.

k. (NN) sample was taken from a lake which takes a ling time for water

replacement because of absence of flow velocity. The sample is a

sediment which accumulated in the water of extremely limited concentration of fine suspraded solid and salt, requiring a large admixture volume of polymer solidifying agent.

297
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Figure 8. Test results of polymer solidifying agent

(relation between admixture volume and

compression strength) (Continued)

302
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Water content: 309.5% pt: 1.239

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Figure 8. (Concluded)

303
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required admixture volume: Ratio of water content to liquid limit

is 1.2 to 2.2 for polymer solidifying agent and 1.18 to 1.95 for

cement solidifying agent, while admixture volume is 2 to 7 kg/m 3 for

the former agent and 80 to 210 kg/m for the latter.

•. The cement solidifying agent used for the tests was a special cement

developed for the treatment of the sediment containing organic substances. As shown in Figure 6, (FG) sample demanded a large admixture volume of the cement. It is because, as discussed before, this

sediment sample is featured by a high total phosphorus and a low

true specific gravity, indicating that the sediment contains a large

quantity of corrosive organic substances.

Safety of Reforming Treatment

Land-based treatment of dredged sediment is subject to exhaust standard

of heavy metals. As shown in Table 13, the sediment samples treated with both

polymer and cement solidifying agents were within the permissible limit of

heavy metals. Table 14 and 15 (a) and (b) show the analytical results against

exhaust standard of heavy metals when the dredged sediment treated with solidifying agent is returned to the farmland. Table 16 are the irrigation water

standards. According to Table 14, zinc (Zn) exceeded its permissible limit,

which is not unusual. Although zinc affects the growth of agricultural products, dredged sludge containing a large quantity of nutrient salt, such as

total nitrogen and total phosphorus, contributes to production (Table 17).

Thus, excessive zinc content is hardly problematic.

CONCLUSION

The present study aims at developing a test method of dredged sediment

treated withpolymer solidifying agent to meet different requirements for

sediment treatment and disposal, and also effective utilization of sediment as

a nutrient salt source to be reduced to farmland and for other purposes. The

study clarified that polymer solidifying agent was one of effective means to

reform dredged sediment and that the sediment treated with the agent could

satisfy those requirements.

Removal of eutrophic sludge sediment improves water quality of lakes and

marshes. Application technology of polymer solidifying agent will certainly

contribute to and accelerate the improvement to a great extent.

The task to be taken up in the future is a comprehensive demonstration

test, including application development of a practical solidifying agent which

promises high safety and workability at treatment site.

308
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REFERENCES

(1) Report of the Field Surveys Commissioned to Sediment Management Association (Lake Mikata of Fukui Prefecture, Harsh Furukawa of Iwate Prefecture, and others).

(2) No. 1 Construction Office, Sewerage Bureau, Tokyo Metropolitan Government, "Evaluation of Improvement Effect of Polymer Coagulant on Slurry

Soil Handling," Monthly Magazine Sewerage, Vol 13, No. 4, pp 39-49.

BIBLIOGRAPHY

Waste disposal (Ministerial Ordinance No. 5 of Prime Minister's

Office, January 17, 1973)

Waste refuse: Ministerial Ordinance of Prime Minister's Office,

Specifying the Judgement Criteria concerning Industrial Waste including Metal, Ministerial Ordinance

No. 66 of Prime Minister's Office, September 30, 1974.

Elution test and content test (Unit of content test is

based on dry weight of sample).

Prevention of

Farmland from

Soil Pollution (Law No. 139, December 25, 1970)

Farmland (1): Notification for Enforcement of the Law concerning

Prevention of Farmland from Soil Pollution, Government

Ordinance No. 204, June 24, 1971

Farmland (2): Control Standard for Prevention of Heavy Metal from

Accumulating in Soil of Farmland Notification No. 149

of Environment Agency, November 8, 1984

Special fertilizer: Designation of Special Fertilizers on the Basis of

Fertilizer Control Art, Notification No. 177 of Ministry of Agriculture and Forestry, June 20, 1950

Urban soil: Provisional Guideline for Prevention of Urban Area

from Soil Pollution, Committee on the Study of Urban

Soil Pollution, January, 1986

Potable water standard: City Water Law, Law No. 177, June 15, 1957

Subleaching waters: Revision of Water Pollution Prevention Act, Enforced

on October 01, 1989

314
BENCH-SCALE TESTS OF INNOVATIVE TREATMENT TECHNOLOGIES

ON SEDIMENTS FROM GREAT LAKES, RIVERS, AND HARBORS

Stephen Garbaciak, Jr.

Environmental Engineer

Remedial Programs Staff

Great Lakes National Program Office

U.S. Environmental Protection Agency

ABSTRACT

The Great Lakes National Program Office has

established the Assessment and Remediation of Contaminated Sediments (ARCS) Program in response to the 1987

Amendments to the Clean Water Act. The ARCS Program

is charged with assessing and demonstrating remedial

options for contaminated sediment problems in the

Great Lakes. As part of the program, the application

to sediments of innovative treatment technologies from

the hazardous waste and mineral processing fields is

being considered. A set of technologies was identified, through a literature survey, for laboratory

testing with sediment samples collected from five

Great Lakes Areas of Concern (Ashtabula River, Ohio;

Buffalo River, New York; Grand Calumet River, Indiana;

Saginaw River and Bay, Michigan; and Sheboygan River,

Wisconsin). Tests were conducted utilizing the

following processes: Zimpro/Passavant's Wet Air Oxidation process, Resource Conservation Company's Basic

Extraction Sludge Treatment, Remediation Technology's

Low Temperature Thermal Desorption process, and SoilTech's Taciuk process. Analyses were performed on

feed materials and all process residues to determine

process efficiency and effectiveness.

INTRODUCTION

The work I am going to discuss was performed as part of the U.S. Environmental Protection Agency's Assessment and Remediation of Contaminated Sediment Program, which we refer to as the ARCS Program. The ARCS Program was

created to address concerns raised in the 1987 amendments to the U.S. Clean

Water Act. Specifically, through the ARCS Program we will develop methods for

assessing the state of contamination in sediments in the Great Lakes, and we

will test technologies for the remediation of contaminated sediments.

The ARCS Program was directed by the U.S. Congress to focus our efforts

on five areas of concern in the Great Lakes: the Sheboygan River in Wisconsin, on Lake Michigan; Saginaw River and Bay in Michigan, on Lake Huron; the

Ashtabula River in Ohio, on Lake Erie; and the Buffalo River in New York, also

on Lake Erie.

315
The sediments in our five study areas are contaminated with a wide variety substances, including heavy metals, nutrients, conventional pollutants,

and organic compounds. These contaminants are generally broken down into two

main groups--inorganic and organic. The inorganics include heavy metals such

as cadmium, chromium, lead, mercury, and zinc. The organic contaminant problems are usually associated with polychlorinated biphenyls (PCBs) and the

polynuclear aromatic hydrocarbons (PAHs). Additionally, the Great Lakes have

been subjected to high loads of nutrients such as phosphorus and nitrogen, as

well as biological oxygen demand from wastewaters.

DISCUSSION

this paper will describe first how we selected the technologies to be

tested; second, the general philosophy of our technology tests; third, the

technologies; and finally, the results of these tests.

In order to identify which technologies should be tested by the ARCS

Program, a literature survey was performed by Mr. Daniel Averett of the

U.S. Army Corps if Engineers. Through this report, Mr. Averett identified a

set of six major technology types that were worthy of further study by the

ARCS Program. Those technology types were: particle classification, bioremediation, immobilization, chemical destruction, extraction, and thermal

destructiDn/extraction. At this time, the bench scale-tests will be discussed

that were conducted in a laboratory setting and performed with three of these

technology types: chemical destruction, extraction, and thermal extraction.

Before the specific tests are discussed, a description of the basic

philosophy employed during these technology evaluations is necessary. Many of

the technologies Mr. Averett identified had not been tested on contaminate

sediments. The technologies had been developed in the hazardous waste treatment field or the mineral processing industry. In order to better understand

how these technologies perform when treating sediments, we chose to evaluate

them in the laboratory, using bench top equipment that simulated the actual

treatment units.

For these bench-scale tests, small volumes of material (from less than

1 A to a maximum of 200 2) were processed through these laboratory units.

Chemical Characterization tests were conducted on the raw sediment material

prior to treatment and on all of the output streams produced by the treatment

process. For some of the technologies, there were only two outputs--a water

and a solid product. For other technologies, there were as many as four products--water, solids, oil, and organic extracts. These end products were

analyzed for the following parameters: PCBs, PAHs, heavy metals, nutrients,

TOC, oil and grease, etc. The results of these tests will be presented later.

This description is of the glassware simulation used for Resource Conservation Company's solvent extraction technology known as the Basic Extraction Sludge Treatment (B.E.S.T.) process. The B.E.S.T. process, as it is

commonly referred to, uses the aliphatic solvent triethylamine to separate

organic contaminants from soil and sediment. The end products of this process

are a dry solid, a water fraction, and an oil fraction that contains the

organic contaminants. This technology does not destroy contaminants, but it

does separate and concentrate them in a greatly reduced volume for further

treatment. This extreme example occurs where the laboratory equipment used

bears very little resemblance to the full-scale process.

316
Remediation Technology's low-temperature thermal desorption unit was

also tested. This technology heats the sediments to temperatures just below

incineration (around 530 °C). The organic contaminants are volatilized from

the sediments and collected in a condenser system. This technology also does

not destroy any contaminants, but it does concentrate the organics in a

greatly reduced volume. Remediation Technology's pilot-scale, truck-mounted

unit was used to process one of out samples from the Ashtabula River. This

example represents the opposite extreme where the laboratory treatment process

very closely resembles the full-scale unit.

The Taciuk process, another low-temperature thermal desorption unit, was

also tested under the ARCS Program. This technology was originally developed

to recover oil from oil shales and tar sands and is now being marketed as a

hazardous waste treatment process.

Finally, Zimpro/Passavant's Wet Air Oxidation unit was evaluated by

ARCS. The Wet Air Oxidation process was developed over 30 years ago for the

treatment of municipal wastewater treatment plant sludges. This process has

been very effective in destroying PAHs and somewhat less effective in breaking

down PCBs. Both of these laboratory units are not quite replicates of their

full-scale counterparts, but they are more advanced that the glassware-type

operattLon described earlier.

RESULTS

The preliminary results of the test conducted on sediments from the

Grand Calumet and Buffalo Rivers indicate that PAHs are a major concern. The

Taciuk process successfully removed over 99 percent of the PAHs from both

samples, and the solid residue from the process successfully passed the

USEPA's hazardous waste test, the Toxicity Characteristic Leaching Procedure,

or TCLP test.

The Wet Air Oxidation process was applied to a sediment sample from the

Grand Calumet River. The initial concentration of PAHs was measures at

24 ppm. After treatment, the PAHs were reduces to 1 ppm, and average destruction efficiency of 96 percent. The destructive capacity of the process varied

with the individual PAH, ranging from a low rate of 82 percent for chrysene to

a high rate of 99.9 percent of benzo(b) fluoranthene.

The data for the tests conducted with the Remediation Technology process

and the B.E.S.T. process are not yet completed. The ReTeC process was tested

on a sediment sample from the Ashtabula River, and the B.E.S.T. Process was

tested on samples from the Buffalo, Grand Calumet, and Saginaw Rivers. Final

reports on all of the bench-scale tests are expected in July 1992.

In conclusion, the early results from out bench-scale tests have demonstrated that the organic contaminants present in Great Lakes sediment can be

removed or destroyed with high efficiencies in a laboratory setting. The next

step in the ARCS program, performing treatment technology demonstrations in

the field, is happening now. By the end of 1992, it will be possible to say

with some authority whether these technol•Jgies work not only in the laboratory

but also in field applications.

317
ORIGIN AND TRANSPORTATION OF AIRBORNE MICROPOLLUTANTS

INTO BOTTOM SEDIMENTS IN AN URBAN RIVER

Mitsumasa Okada

Laboratory of Environmental Chemistry

Faculty of Engineering, Hiroshima University

1-4 Kagamiyama, Higashi-Hiroshima 724 Japan

Yoji Kurimoto, Kazuhiro Yoshida, Tatsuo Kotake

Japan Bottom Sediment Management Association

2-7-12 Tsukiji, Chuo-ku, Tokyo 104 Japan

ABSTRACT

The origin, transport, and fate of hydrocarbons

in the Nogawa River basin, a typical urban river running through residential areas in suburban Tokyo, was

studied both in normal and high water conditions.

Aliphatic hydrocarbons (nSHCs) and PAHs found in the

river water in normal water condition originated mainly from gray water. nSHCs and PAHs found in high

water originated mainly from runoff water. The also

originated from roadside dust and were washed off into

runoff water. nSHCs accumulated in the bottom sediments during high water, but they released back to

water during normal water condition to decrease concentration in the sediments. On the contrary, PAHs

always accumulated in the bottom sediments by their

high absorbability onto sediments, and the highest

concentration of PAHs was noted in the bottom sediments. Atmospheric nSHCs and PAHs seemed to be the

origin of roadside dust. They were transported onto

the surface of road during rain. Although the emission of automobiles seemed to be the origin of nSHCs,

it is most probable that PAH originated from other

distant sources than automobiles emission nearby.

INTRODUCTION

Numerous chemicals that originated from human activities are known to be

discharged into environment in various forms such as suspended particulate,

dust, and mist. These substances are directly discharged into water bodies or

transported through atmosphere, and a part of them is deposited on land or

directly on water surface. In rainy days, those airborne chemicals deposited

on land in previous dry weather period will be washed off by stormwater.

Although most of stormwater runoff is introduced into the sewer system

in the area with a combined sewer system, stormwater overflow is still discharged directly into public water bodies without any treatment. Chemicals

are also discharged directly into public waters in the areas with separate

sewer system and, of course, with no publicly owned sewer system. Some of

318
these chemicals are known to be degraded biologically, whereas others remain

in the bottom sediments of the water. They may have significant impact on

aquatic ecosystem. Jensen (1983) estimated the input and output of petroleum

hydrocarbons in a coastal marine area of Denmark and reported that 21 percent

of the total weight of C1 2 -C 3 6 fraction has deposited on the sediment.

A number of investigations have been reported on the importance of

stormwater runoff as a major pathway of chemicals from land origin into an

aquatic environment (Browne 1980, Field at al. 1980, Duda et al. 1982). However, there have been reported few studies on the behavior of hydrophobic

petroleum hydrocarbons.

Sources of hydrocarbons to urban stormwaters include accidental spills,

deliberate dumping of waste oil and fuels, emission from engines, crankcase

drippings, fallout from atmospheric particulates, spillage of the products

during refining and transportation, natural seepage, and natural biogenic

sources (Fam et al. 1987). Brown et al. (1985) has shown that the most probable source of crankcase oil-like petrochemical hydrocarbons found in the

sediments of the Hillsbrough River was the stormwater runoff. Walkeham (1977)

has reported that the petroleum hydrocarbon in the sediment in Lake Washington

bordered by Seattle on the west was almost from urban stormwater runoff, and

the contribution from naturally occurring hydrocarbons appeared to be minor.

Hamilton et al. (1984) pointed out that the plant wax hydrocarbons found in

the suspended matter in the upper Green-Duwamish river, Washington, originated

from algae and that a secondary sewage treatment plant was a major point

source of hydrocarbons to the river. Sternstorm et al. (1984) and Fam et al.

(1987) investigated the hydrocarbons found in 15 watersheds in the San Francisco Bay area and reported that the hydrocarbons in undeveloped areas were of

biogenic origins and that the major anthropogenic sources of hydrocarbons in

the stormwater runoff from urban areas originated from motor oil and diesel

fuel.

Those reports estimated that hydrocarbons found in aquatic environments

such as rivers, lakes, and estuary were transported by stormwater runoff from

urban area where hydrocarbons exist in the form of smoke and soot of the factory and emission of the incomplete combustion of automobiles during cruising,

deceleration, and idling. The objective of this study is to know the origin,

the transport, and the fate of the petroleum hydrocarbons, i.e. aliphatic and

polycyclic aromatic hydrocarbons, in bottom sediments of urban river with

special emphasis on the contribution of stormwater runoff and the role of

bottom sediments.

MATERIALS AND METHODS

The Nogawa River is a tributary of the Tama River in Tokyo. The river

originates from a spring in the City of Kokubunji and runs thorough residential areas of suburban Tokyo with several inflows of spring water and numerous

discharges of urban runoff and gray water. The area of the Nogawa River basin

is 46.3 km2 with population of 410,000. Eighty-seven percent of the basin was

served with public-owned separate sewer system. In the remaining 13 percent

with no sewer system, gray water is allowed to be discharged directly into the

river without any treatment. Average rate of flow is 20 x 103 m3 day-1 , and

82 percent originates from gray water. The river finally flows into the Tama

River at Setagaya-ku in Tokyo.

319
River water and bottom sediment were collected at a sampling station in

the mid-stream of the river. Street dust, runoff water, graywater, dry precipitation, and rain water were sampled in the upperbasin of the sampling

station. Water samples were collected in a glass bottle and transported to

laboratory after NaCl was added to 3 percent and pH was adjusted to 2.0 with

1 N HCl in situ. Petroleum hydrocarbons were extracted from the sample by

fractionation into dichloromethane (sample: dichloromethane = 10:3 in volume). The extract was dried over sodium sulfate and excess dichloromethane

was evaporated by Kuderna-Danish (KD) evaporative concentration to have the

final volume of 1 ml. The concentrate was charged into a glass column packed

with silica gel (10 mm by 300 mm). Aliphatic hydrocarbons (nSHCs) were eluted

with 30 ml of n-hexane. Polycyclic aromatic hydrocarbons (PAHs) were eluted

with 30 ml of n-hexane/benzen solution (1:1 v/v). Each fraction was concentrated and dried by a rotary evaporator.

nSHCs were dissolved into 1 ml of hexane and separated and identified by

a gas chromatography (Shimazu, GC-14A) with a hydrogen flame ionization detector. A capillary glass column (0.25 mm by 25 m) packed with ULBON HR-101

(Chromatopacking Center Co.) was used. Temperature of the injector was

3200 C, and that in the column increased from 60 to 2400 C with the rate of

40 C per minute.

PAHs were dissolved into 2 ml of methanol and determined by a high performance liquid chromatography (Tosoh, model CCPE) with a column packed with

TSK gel (ODS-8OTM, 4.6 x 250 mm) at room temperature. The elute used was

methanol/water solution (95:5, v/v) with a flow rate of 1.0 ml/min. A fluorescence detector (Shimazu, RF 535) at a wave length of 295 nm for excitation

and 490 nm for emission was used.

Solid samples were sieved to remove large particles such as stones and

litters and were preserved in amber bottles at -200 C. Bottom sediments were

centrifuged at 3,000 rpm for 10 min to remove excess water. Prior to hydrocarbon analysis, a part of each sample was ovendried at 1050 C for two hours

to determine dry weight.

Petroleum hydrocarbons in the solid samples were extracted by dichloromethane with mortars. The extract was passed through a glass fibre filter

(Whatman GF/F). The filtrate was washed successively with 10 percent sodium

carbonate, 1N sodium hydroxide and 1 N HCl, and finally, was neutralized by

water. The sample was dried over sodium sulfate and concentrated and dried by

a rotary evaporator.

The concentrate was charged to the column of silica gel, and nSHCs and

PAHs fractions were separated. The concentration of each component was determined by the same procedure as water sample.

RESULTS AND DISCUSSION

nSHCs and PAHs in the River

Concentrations of nSHCs with carbon number from 11 to 30 in the bottom

sediments and river waters both in normal and high water conditions are shown

in Figure 1. The higher concentrations of nSHCs were noted in samples during

high water than that during normal water condition. It is clear that, in the

320
S20

U bottom sediments

S1o

3

13 normal water

2 M high water

- 1

U sediments (normal)

Usediments (high)

U0.1

0.0

1112131415161718192021222324252627282930

carbon number

Figure 1. Concentrations of nSHCs with carbon number from

11 to 30 in the bottom sediments and river

waters both in normal and high water conditions.

basis of volume, there are far larger concentrations of nSHCs in the bottom

sediments (surface sediments).

The bottom section of Figure I shows calculated concentrations of nSHCs

assuming bottom sediments were resuspended with the same concentration as the

suspended solids (SS) concentrations in the water both in normal and high

water conditions, 3.85 mg 1-1 and 8.64 mg 1-1, respectively. The amount of

nSHCs attached to particles in the bottom sediments were far smaller than

those in water. More than 50 percent of nSHCs in the river water with carbon

number more than 23 were attached to the SS. The percent attached increased

with the increase in the number of carbon, and more than 90 percent of nSHCs

with carbon number of 29 and 30 were associated with SS. Both attached and

dissolved concentrations of nSHCs in the water, therefore, were higher than

the concentrations estimated from the attached concentrations of nHSCs in the

bottom sediments. Thus, nSHCs in the water seemed not to have accumulated in

the bottom sediments.

Concentrations of PAHs, i.e., benzo(a)anthracene (B(a)A), benzo(k)fluoranthene (B(K)F), benzo(a)pyrene (B(a)P) and benzo(ghi)perylene (B(ghi)P), in

the sediments and water samples are shown in Figure 2. Similar to nSHCs,

volumetric concentrations of PAHs in the bottom sediments were far higher than

those in the water samples. Concentrations in the high water condition were

321
also higher than those in normal water. Contrary to nSHCs, PAHs in the bottom

sediments were higher than those in water if they were resuspended into water

with the same SS concentration as the water. Therefore, PAHs seemed to have

accumulated in the bottom sediments in higher concentrations than in the

water.

-~500-

0 U bottom sediments

o 300-

p200-

0 c100-

1.2 " high water

0 normal water

0.8

" 0.4_

U sediments (norml)

U sediments (high)

2

0

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Figure 2. Concentrations of PAHs in the sediments and water samples

Loadings of nSHCs from the Basin

To estimate origin and fate of petroleum hydrocarbons in the bottom

sediments, loadings from various sources in the upper basin of the sampling

point were estimated based on the monitoring data. Figure 3 shows three possible sources of nSHCs in normal water condition. The largest source of nSHCs

discharge was gray water, and contributions of other sources were almost

negligible.

Figure 4 shows total amount of discharge into the upper basin, i.e.

input loading, and output loading at the point of sampling, which is the daily

amount of nSHCs passed at the point of sampling with the flow of water. The

amount of output was larger than that of input.

There should be some contribution of so-called self-purification with

the flow of river. The input of SS by gray water, for example, was estimated

to be 162 kg day-1. Total output was only 39.7 kg day-1 . Thus, significant

self-purification, at least more than 75.5 percent, can be expected through

322
12 spring water

6" gray water

U dry pmreipitation

11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 carbon number

Figure 3. Sources of nSHCs in normal water condition

20

U input

-2 output

10

0

11 12 13 14 15 16 17 18 19 20 2122 23 24 25 26 27 28 29 30

carbon number

Figure 4. Input and output loadings

sedimentation. Therefore, nSHCs attached to SS might be removed with the

sedimentation of SS. The fact that the output of nSHCs was larger than the

input, on the contrary, indicates that there should be other sources of nSHCs

discharge.

Figure 5 shows two additional sources of nSHCs that may contribute only

in high water condition. The largest source of nSHCs discharge was urban

runoff. The contribution of rain water itself was negligible. It must be

noted that the contribution of urban runoff was approximately 10 times as

large as that of gray water. Figure 6 shows input and output of nSHCs. Contrary to the normal water condition, the amount of input was larger than that

of output, indicating normal self-purification.

323
S100

S80 rain water

urban rnmoff

j6 0

410

02

1 12 13 14 15 16 17 18 19 20 2122 23 24 25 26 27 28 29 30

carbon number

Figure 5. Sources of nSHCs in high water condition

120

100. storm input

0 storm output

~80-

15 60.

*-40

-20L

11 1213 14 1516 171819 2602f22 232425 26 2728 2930

carbon number

Figure 6. Input and output loadings of nSHCs in high water condition

Thus, nSHCs were discharged into river mainly by urban runoff. Most of

nSCHs in urban runoff (more than 90 percent, not shown here) were associated

with suspended sediments. Hoffman et al. (1984) reported that petroleum

hydrocarbons were transported with runoff water and, especially, that most of

the hydrocarbons were associated with suspended particles during high water in

the estuarine water of Rhode Island. Latimer et al. (1986) reported that most

of petroleum hydrocarbons in runoff water were adsorbed on SS.

Generally, urban runoff water contains various particles of terrestrial

origin such as fine particles from asphalt and concrete pavements, and soil

particles. It is most likely, therefore, the hydrocarbons discharged into the

Nogawa River with runoff water may be adsorbed onto SS and deposited on the

bottom of the river. The accumulated nSHCs in the bottom sediments seemed to

be another source of nSHCs discharge in dry weather condition.

Loadings of PAils from the Basin

Figure 7 shows three possible sources of PAHs in normal water condition.

Similar to nSCHh, the largest source of PAils discharge was gray water, and

contributions of other sources were negligible. Input and output loadings are

also shown in Figure 7. Contrary to nSHCs, output was smaller than input

324
40 U spring water N input graywater o output

30 dry precipitation

S20

0 L

B(a)A B(k)F B(a)P B(ghi)P B(a)A B(k)F B(a)P B(ghi)P

Figure 7. Sources and input and output loadings of PAHs in

normal water condition

indicating accumulation of PAHs in the bottom sediments even in normal water

condition.

Figure 8 shows two additional sources of PAHs associated with rain. The

largest source of PAils discharge was also urban runoff. The contribution of

rain water was negligible. It is remarkable that the contribution of urban

runoff was more than 100 times as large as that of gray water. Input and

output of PAHs in high water condition are shown in Figure 8. The output was

negligible in spite of large amount of PAis input by urban runoff.

4000- 

an ae rw storm input 3000 urban runoff [ storm output

S2000

1I000-

B(a)A B(k)F B(a)P B(ghi)P B(a)A B(k)F B(a)P B(ghi)P

Figure 8. Sources and input and output loadings of PAHs

in high water condition

Most PAHs discharged into the river originated from urban runoff. Similar to nSHCs, most of them (more than 95 percent, not shown here) were associated with suspended sediments. It is well known that large amount of PAls are

adsorbed onto suspended sediments (Latimer et al. 1986, Hoffman et al. 1982,

1984, 1985, Herrmann 1981). It is most likely, therefore, PAHs discharged

into the river with runoff water may also be adsorbed onto SS and deposited on

the bottom of the river. The higher absorbability of PAHs than nSHCs may

enhance the adsorption onto both suspended and bottom sediments with little

325
remaining PAHs in water and little release back into water. Thus, most of

PAHs discharged into the basin accumulated in the bottom sediments.

Transportation of Airborne Hydrocarbons to Runoff Water

It is known that petroleum hydrocarbons are discharged into atmosphere

in the form of smoke and soot from factories and by emission of incomplete

combustion from automobiles. They are washed out by rain down to land surface

and transported with stormwater runoff from urban area (Herrmann 1981).

Yamane et al. (1991) reported concentrations of nSHCs and PAHs in the

surface soil of the Nogawa Park, with was loc-ted near the sampling site in

the Nogawa River, in dust of roadside nearby, and on route 20 with heavy traffic in contrast with the residential district of the Nogawa basin.

Only nSHCs with carbon number of 27 and 29 were detected in the surface

soil of the Nogawa park and were below 1 pg g- 1 . Therefore, it is not likely

that nSHCs in the surface of the soil were transported to runoff water. The

distribution of hydrocarbons in the street dust corresponded with that of

runoff water, thus indicating to be a major source of nSHCs to runoff water.

The concentration of nSHCs in the dust of route 20 was far higher than that in

residential area. It is well known that major hydrocarbons used in motor oil

are those with carbon number around 23; particle hydrocarbons in emission from

diesel engine are mainly those with around 20; and those in gasoline and light

oil are mainly those with around 14 (Simoneit et al. 1981, Brown 1985, Fam et

al. 1987). The origin of street dust seemed to be emission of automobiles

nearby.

PAH contents in park soil were ca. 5 ng g- 1 dry weight and in street

dust and in roadside dust of route 20 ranged from 20 to 40 ng g-1. The nSHCs

in roadside dust of route 20 was 10-30 times as high as that in street dust of

residential area, whereas concentrations of PAHs were almost the same. Therefore, it is most probable that PAHs did not originate from emission of

automobiles.

Lygren et al. (1984) reported that hydrocarbons are deposited within

100 m from highway as small particles of dustfall in Norway. In the Nogawa

River basin, hydrocarbons contents in rainwater was negligible. Most hydrocarbons in emission of automobiles, therefore, seemed not to suspend in

atmosphere, but adsorbed on fine particles of dust, greater than 10 pm, and

deposited on road surface or surrounding area. Hagenmaier et al. (1986)

determined PAH concentrations in surface sediments of the River Neckar,

primary sludge of wastewater and organic fraction of municipal refuse.

Furthermore, PAH originated party from traffic and mostly from incompletely

combustion of woods at home.

The concentration of nSHCs and PAHs in the dust of roadside did not show

significant increase during consecutive fine days (not shown here). However,

they increased after rainfall. There are no sources except rainfall to

increase hydrocarbon contents in the roadside dust. Thus, it seemed that

raindrops adsorbed hydrocarbons in the atmospheric dust and precipitated on

the road to increase their concentration in spite of large amount of output

with urban runoff.

326
CONCLUSIONS

The origin, transport, and fate of hydrocarbons in the Nogawa River

basin, a typical urban river running through residential areas in suburban

Tokyo, was studied both in normal and high water conditions. The specific

conclusions derived from this study are as follows:

A. nSHCs and PAHs found in the river water in normal water condition

originated mainly from gray water.

k. nSHCs and PAHs found in high water originated mainly from runoff

water. They also originated from roadside dust and were washed off

into runoff water.

c. nSHCs accumulated in the bottom sediments during high water, but

they were released back to water during normal water condition to

decrease concentration in the sediments. On the contrary, PAHs

always accumulated in the bottom sediments by their high absorbability onto sediments, and the highest concentration of PAHs were

noted in the bottom sediments.

•. Atmospheric nSHCs and PAHs seemed to be origin of roadside dust.

They were transported onto the surface of the road during rain.

Although the emission of automobiles seemed to be the origin of

nSHCs, it is most probable that PAH originated from other distant

sources than automobiles emission nearby.

REFERENCES

Browne, F. X. 1980. "Water Pollution, NonpoLnt Sources." Journal Water

Pollution Control Federation, Vol 52, pp 1506-1509.

Brown, R. C., Pierce, R. H., and Rice, S. A. 1985. "Hydrocarbon Contamination in Sediments from Urban Stormwater Runoff," Marine Pollution Bulletin,

Vol 16, pp 236-240.

Duda, A. H., Lenat, D. R., and Penrose, D. L. 1982. "Water Quality in Urban

Streams - What We Can Expect," Journal Water Pollution Control Federation,

Vol 54, pp 1139-1147.

Fam. S., Stenstrom, M. K., and Silverman, G. S. 1987. "Hydrocarbon in Urban

Runoff," Journal Environment, England, Vol 113, pp 1032-1046.

Field, R., and CibLk, C. 1980. "Urban Runoff and Combined Sewer Overflow,"

Journal Water Pollution Control Federation, Vol 52, pp 1290-1307.

Hagenmaier, H., Kaut, H., and Kraus, P. 1986. "Analysis of PolycyclLc Aromatic Hydrocarbons in Sediment, Sewage Sludges, and Composts from Municipal

Refuse by HPLC," International Journal Environ. Anal. Chem., Vol 23, pp 331-

345.

Hamillton, S. E., Bates, T. S., and Cline, J. D. 1984. "Sources and Transport of Hydrocarbons in the Green-Duwamish River, Washington, Environmental

Science Technology, Vol 18, pp 72-79.

327
Herrmann, R. 1981. "Transport of Polycyclic Aromatic Hydrocarbons Through a

Party Urbanized River Basin," Water, Air, Soll Pollution, Vol 16, pp 445-467.

Hoffman, E. J., Latimer, J. S., Hunt, C. D., Mills, G. L., and Quinn, J. G.

1985. "Stormwater Runoff from Highways," Water Air and Soll Pollution,

Vol 25, pp 349-364.

Hoffman, E. J., Latimer, J. S., Mills, G. L., and Quinn, J. G. 1982. "Petroleum Hydrocarbons in Urban Runoff from a Commercial Land Use Area," Journal

Water Pollution Control Federation, Vol 54, pp 1517-1525.

Hoffmann, E. J., Mills, G. L., Latimer, J. S., and Quinn, J. G. 1984. "Urban

Runoff as a Source of Polycyclic Aromatics to Coastal Waters," Environmental

Science and Technology, Vol 18, pp 580-587.

Jensen, K. 1983. "Sources and Routes of Removal of Petroleum Hydrocarbons in

a Danish Marine Inlet," Oil and Petrochemical Pollution, Vol 1, pp 207-216.

Latimer, J. S., Mills, G. L., Hoffman, E. J., and Quinn, J. G. 1986. "Treatment of Solids and Petroleum Hydrocarbons in Storm Runoff with an On-site

Detention Basin," Bull. Environment Contamination Toxicology, Vol 36, pp 548-

555.

Lygren, E., GJessing, E., and Berglind, L. 1984. "Pollution Transport from a

Highway," Science of the Total Environment, Vol 33, pp 147-159.

Simoneit, B. R. T., and Majurek, M. A. 1981. "Air Pollution: The Organic

Components," CRC Critical Reviews in Environmental Control, Vol 11,

pp 219-276.

Stenstrom, M. K., Silvermann, G. S., and Bursztynsky, T. A. 1984. "Oil and

Grease in Urban Stormwaters," Journal Environment England, Vol 110, pp 58-72.

Walkeham, S. G. 1977. "A Characterization of the Sources of Petroleum Hydrocarbon in Lake Washington, Journal Water Pollution Control Federation, Vol 49,

pp 1680-1687.

Yamane, A., Nagashima, I., Ohkubo, T., Okada, M., and Murakami, A. 1981.

"Stormwater Runoff of Hydrocarbons in the Tama River Basin in Tokyo (Japan)

and Their Fate in the River," Water Science and Technology, Vol 22,

pp 119-126.

328
QUESTIONS AND ANSWERS

15th Meeting, US/Japan Experts on Management

of Bottom Sediments Containing Toxic Substances

Mr. Taizo Nakano

Q: Describe contaminants in sediments at Osaka.

A: Bottom sediments, organic substances, heavy metals, disposed in other

areas and do not pass standards.

Q: What kind of dredges were used - hopper or cutter suction?

A: Most cases resort to hopper types.

Q: What size were the areas?

A: Approximately 300 hectares. Volume was 30 MCM of dredged substances.

Mr. Norman Francingues

Q: From these biological examples of treatment, can you give us some results?

A: Results are not available on these examples but we have results from other

sites that show reductions after only a few weeks.

Q: Techniques have been demonstrated and considered; do you have plans for

major demonstration project? If so, when, where and who would bear costs?

A: We have an ongoing project in Waukegan and can get you some information

through EPA.

Dr. James Brannon

Q: After sample did you change water on the upper level every day?

A: We are combining the water with the mud.

Q: Did they contain organic substances? If so, how much?

A: Yes, about 12 ppm PCB.

Comment: We found centrifugal force took out sediment.

Q: Is time lapse important in a time like this?

A: Time is important. Samples change over time. Test samples as soon as

possible to maintain aerobic condition. Do it under nitrogen atmosphere.

Q: Have you put sands through wet and dry cycles to see how it affects

release rates?

A: No, due to finding we just had a wet cycle; however, we did recent samples

and saw slight increase.

Q: Do you have estimate of PCB rate loss in that 1,200-ppm sample?

A: On the order of 29 mg/m2/hr in that sample.

Q: 1,200 ppm was large amount - why so big?

329
A: At New Bedford, material from transforms fell into the water.

Q: What is condition where sample taken?

A: The water was shallow and the sedimentation was thin.

Mr. Takeo Maekawa

Q: We have done research on removing solids from effluents at confined sites.

Use of chemicals and polymers are effective for solid removal but we get

toxicity to organisms. Do you get similar results?

A: Coagulates have been used in landfills but have had no such problems.

Q: You referenced use of a pump. What kind? How did the solids react?

A: Oozer pump dredge reported in past meetings. Vacuum pump characterized as

high concentration or density dredge.

Dr. Thomas Fredette

Q: In order to separate pollutants, capping is becoming popular in Japan.

When selecting thickness or siting of capping, might it provide environment for organisms.

A: Yes. We are concerned about organisms burrowing into contaminated

material so we must get proper thickness. We believe these sites are

beneficial to fisherman. Their topographic shape is similar to ocean

floor and attracts flounder and other fish.

Q: Any conflict with fisherman?

A: Some sites were closed because fishermen became so plentiful. However, in

nine sites this has been no problem.

Q: What is capping material and source? Do you have to compete?

A: Usually another dredged material without contaminants. No conflict with

construction industry--not construction-grade sand.

Q: (1) Basic philosophy is to directly cap pollutant. Why transport before?

(2) Water depth of 90M--do you have problem with turbidity?

(3) What is thickness?

A: (1) Need to increase water depth like channel, so to construct cap in

place, must transport.

(2) We consider water column impacts and have a number of management

options to consider in order to reduce impact.

(3) We try for range of 50 to 100 cm thick.

Q: (1) How do you prevent mix of contaminated and cap material?

(2) Can you cap with a hydraulic dredge?

A: (1) Mix was a concern, but our cores show a sharp line. The contained

material seems to have strength and integrity.

(2) Behavior of hydraulic dredge capping is similar to mechanical. Lower

density and more spread would be with hydraulic.

Comment: If you submerge the pipe in hydraulic dredge, it might give better

concentration.

330
Q: What sort of time constraints are put on you by EPA to cap after placing

contaminated material?

A: We like to have capping start within 2 weeks of placing contaminated material. Time to complete is less critical, usually takes a month or so.

Mr. Akira Teramoto

Q: Where in relation to dredge did you take measurements?

A: We took several measurements--tip and rear of dredge to center, left, and

right.

Mr. Hiroyuki Sakamoto

Q: What solidifers did you use?

A: A cement-like compound as solidifying agent.

Q: (1) What soil parameters did you use to see if soil has workability?

(2) How do you adjust its workability?

A: We use flow test. Fluidity is critical, neither too hard or too soft. We

use flow test standard for Japan. Soil may sometimes have large foreign

objects. We use screen to remove. May add water for fluidity. We would

look at diffusion through test.

Mr. Makoto Natori

Q: Have you tried to identify biological organisms used?

A: Very difficult to do; we did not in this case.

Q: You are returning water to marsh, but may it not contain a lot of

phosphate?

A: Depends on care, but here the water at bottom has higher level of

phosphate and supernatant has lesser level.

Mr. Hideo Hamabata and Mr. Yusuke Suda

Q: The cost for dredging seemed high. What was cost/CM?

A: That was careless mistake. I will revise now - dredge $19M, capping $13M,

porous oxidation $300K, conveyance $500K, and converse river water $LIM.

As for unit cost, I have data but cannot pull it out now.

Q: Are there concerns with heavy metal or petroleum by-products?

A: In Japan, we have been able to dispose of heavy metals below standards in

most areas.

Q: You mentioned micro-organisms. In the future can we improve the situation

with bio-engineering?

A: Yes, some are usiiug it, but it is beyond scope of Sea Blue.

Q: Do you backwash or forewash?

A: The system is the crucial point. We backwash and use a dual system.

331
Q: Organisms present would depend on time of year. Some workable in Tokyo

may not be so here in LA. Is it not so?

A: It is extremely crucial how we process the organisms. They may not react

as we humans might wish. What works in Tokyo may well not work in LA.

Technology process is important.

Mr. Wads

Q: How much cementitions material does he mix to get the results?

A: It depends on water content, from 120 to 170 kilo per cubic meter.

Q: What is the approximated cost per kilo of material?

A: 20,000 yen/ton approximately.

Mr. Thomas Myers

Q: Do you know what are the reasons why in Harbor of Buffalo results were so

different?

A: No, I do not.

Q: Data are significantly different for what I have. Unthinkable these heavy

metals.

A: Geochemistry of metals and sediments is complex. Colloidal system,

organic carbon can be mobilized by solidification process. We began with

the ideal that we could mobilize metals. We are concerned about misapplication of this technology.

Comment: Adding cement to mobilize metals is well established in the mining

industry of the United States.

Q: Could you get these leaching speeds if you repeat the process many times?

A: Test done to remove the metals sequentially. Then tested untreated material for comparison. We tried to leach as much as we could so in the

final analysis speed was not critical.

Comment: From the presentations here it is apparent the Japanese are ahead of

the US in this field. It would be helpful in future if you could

share chemical sedimentation techniques with us.

Q: What kind of solidifying agent did you use--and the unconfined compressive

strengths. It would seem the amount of compound would impact the leaching.

A: We have run different tests with different agents and can supply results

to you. In general, we have found little difference in results due to use

of different agents. The agent used definitely impacts on the strength of

the resulting material. These data are available. We have also done

durability testing.

Mr. Kivoihi Nikaido

Q: What kind of polymer did you use?

A: Mainly polyachrin acid and other natural polymers.

332
Mr. Steve Garbaciak

Q: Will you come up with ballpark estimates on cost per cy?

A: Yes, we will have the Feb results (report) that will give estimate of

upscaling to full operation.

Q: I compliment you on an interesting report. Have you conducted tests in 1

to 1.5M? Have you tested for leaching?

A: Material represents top 1 meter of area--removed with clam shell. Bulk of

contamination in Great Lakes increases the deeper you go. Leaching tests

are being subjected on heavy organic rather than heavy nutrient samples.

Q: Did you run tests before treatment?

A: TCLP test on only one rather than all.

Q: Can we get literature for Great Lakes program?

A: Sure. Leave me your name.

Dr. Mitsumasa Okada

Q: Explain how you collected roadside dust samples--collect dust or system?

A: Broom and dust collectors.

Q: Is consideration being given to trapping pollutants before getting into

water course and becoming sediment?

A: Not during this research, but we know that in cases of separated sewer

systems, storm water goes into supply systems, particularly in new development. Rain water goes into public supply system. Japanese government

is developing ponds to capture rainfall for the PAH. It will be easy to

remove--easily attaches to suspended sediments. This also applies to P&N.

Q: Have you looked at metals through atmospheric sediments?

A: No, have no interest, vowed to never study heavy metals.

Comment: U.S. interested in using wetlands to help in both urban and rural

areas to clean runoff.

Response: The climate and land are different in Japan. Don't know whether

the process would apply there. Hope this conference continues

forever.

333
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MANAGEMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC

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13. ABSTRACT (Maximum 200 words)

The 15th U.S./Japan Meeting on Management of Bottom Sediments Containing

Toxic Substances was held 19-21 November 1991 in San Pedro, California. The

meeting is held annually through an agreement with the U.S. Army Corps of Engineers and the Japan Ministry of Transport to provide a forum for presentation of

papers and in-depth discussion on dredging and disposal of contaminated

sediment.

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Contaminated sediments Sedimentation 345

Dredging Toxicology 16. PRICE CODE

Marine deposits

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