RD-A±,63 709 MANAGEMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC 1/5

SUBSTANCES: PROCEEDINGS 0.. (U) CORPS OF ENGINEERS FORT BELVOIR YA MATER RESOURCES SUPPORT CE.. T R PATIN UNLSIID OCT 85 F/G 13/2 N

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MICROCOPY RESOLUTION TEST CHART

NADtONAI. BUREAU OF STANDOARDS-1%63-A
US Army Corps of EngineersWt

Water Resources

SSupport Center

Management of Bottom Sediments

0 Containing Toxic Substances

Proceedings of the 10th U. S./Japan .-.

Experts Meeting

30-31 October 1984

Kyoto, Japan

Thomas R. Patin, Editor L'C s FD

EBO06 06B

k IIE L E C T E 

" ..-

LuJ This docu en ha for Publicr In li beei 0 PProved di,.s l as and sae; its

October 1985

• . . . ,- ., . . . . , .. . .. .. . . . .19..6
Unclassified 5

SECURITY CLASSIFICATION OF THIS PAGE rU7,n D. te Fnotrd)RE D I S UC ON REPORT DOCUMENTATION PAGE BEFORE COMPLETING FORM

I REPORT NUMBER 2. GOVT ACCESSION NO.1 ECiPIENT'S CATALOG NUMBER

iopl~b3 9 4. TITLE (and SublIII.) TYPE OF REPORT & PERIOD COVERED .

MANAGEMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC Final report

SUBSTANCES: PROCEEDINGS OF THE 10TH U. S.1 _____________

JAPANEXPETS METIN PERFORMING ORG. REPORT NUMBER

7. AUTHOR(.) 6COTATOR GRANT NUMBER'S) le.

Thomas R. Patin, Editor.IF. .

9 PERFORMING ORGANIZATION N AME AND ADDRESS 10. PROGS.AM ELEMENT. PROJECT, TASK AREA 6 woRK UNIT NumaERs

Dredging Operations Technical Support Program

1 1. CONTROLLING OFFICE N AME AND ADORE SS 12 REPORT DATE

Water Resources Support Center October 1985

Fort Belvoir, Virginia 22060 13. NUMBER OF PAGES

414 14 MONITORING AGENCY NAME & AOORESS(lf different froms Controlling Office) IS SECURITY CLASS. 'of this repot)

U. S. Army Engineer Waterways Experiment Station Unclassified

Environmental LaboratoryL. OCSIFCTNDOGRIG -

P0 Box 631, Vicksburg, Mississippi 39180 I~ CSDL

16 DISTRIBUTION STATEMENT (of this Report)

Approved for public release; distribution unlimited.

17, DISTRIBUTION STATEMENT (of th. abatract .sitred In Block 20, Of different from Report)

III SUPPLEMENTARY NOTES

Available from National Technical Information Service, 5285 Port Royal Road,

Springfield, Virginia 22161.

19. KEY WORDS lConinu. on reee@ side It necess.ary ad identify by block num~ber)

Dredging

Marine deposits

Sedimentation

Toxicology

20. AsTR ACT (Caeho is reer * aid. if Imecevm md Identify by block num.ber)

The 10th U. S./Japan Meeting on Management of Bottom Sediments Containing Toxic Substances was held 30-31 October 1984 in Kyoto, Japan. The meeting0

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 nn dredging and disposal of contaminated

sediment.

Do I F ,1 1473 EDITION OF I NOV 6S IS OBSOLE TE

SECU RI TV CL ASSI FIC A TION O F TN IS P A -E 'Wh t 17.er. FnIO..dI

It 1.
PREFACE

The 10th U. S./Japan Experts Meeting on Management of Bottom Sediments

Containing Toxic Substances was held 30-31 October 1984 in Kyoto, Japan. 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.

COL George R. Kleb, Commander and Director of the Water Resources Support Center (WRSC), was the U. S. Chairman. Mr. Ikuhiko Yamashita, Ministry

of Transport, Tokyo, Japan, was the Japanese Chairman.

Coordinator of the organizational activities and editor of this report _

was Mr. Thomas R. Patin, program assistant, Dredging Operations Technical Sup- LAW

port Program (DOTS), U. S. Army Engineer Waterways Experiment Station (WES),

Vicksburg, Miss. Ms. Jamie W. Leach and Ms. Betty W. Watson, WES Publications

and Graphic Arts Division, were instrumental in editing, cooreinating, and

preparing the text. Mr. Charles C. Calhoun, Jr., was Program Manager, DOTS,

at the time of the meeting. Dr. Robert M. Engler is the present Manager of

the DOTS Program.

. o

Accesion For

NTIS CRA&I

DTIC TAB

U;.anro.; ced

J'ustit:.to. I " -

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CONTENTS. '

Page

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ATTENDEES ATENEE........................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .* . 4

AGENDA ................... ..................... ... 8

JOINT COMMUNIQUE................. ................. ... 11

LEGAL SYSTEM AND WORKS FOR PRESERVATION OF THE PORT, HARBOUR, AND

MARINE ENVIRONMENT IN JAPAN:by T. Ikeda .... ............... ... 12

A MODEL OF NITROGEN RELEASE FROM BOTTOM SEDIMENTS'

by M. Hosomi, M. Okada, and R. Sudo ..... ................. ... 30

STUDY ON CHEMICAL BEHAVIOR BETWEEN SEDIMENT AND UPPER WATER'

by H. Nakanishi, M. Ukita, and Y. Kawal ............... 63

EVALUATION OF THE FACTORS GOVERNING THE MOBILITY OF DREDGED

MATERIAL PLACED AT OPEN WATER DISPOSAL SITES'by W. F. Bohlen .... 85

NUMERICAL PREDICTION ON THE EFFECT OF PHOSPHORUS RELEASE CONTROL BY

SEDIMENT DREDGING'by T. Hore ....... .................... . . 101

ECOLOGICAL EVALUATION OF ORGANOTIN-CONTAMINATED SEDIMENT'

by M. H. Salazar and S. M. Salazar ................. 127

CHARACTERIZATION OF SEDIMENT CONTAMINATION UTILIZING BIOASSAY/

BIOACCUMULATIONTESTING;by J. M. Mansky .... ............... ... 150

IDENTIFICATION OF PROMISING CONCEPTS FOR TREATMENT OF CONTAMINATED

SEDIMENTS'by N. R. Francinques, Jr ...... .................. ... 162

THE INFLUENCE OF ACCUMULATING ORGANIC SEDIMENT ON THE MAIN. -

ENVIRONMENT IN OSAKA BAY'by M. Kawaguchi, T. Saski,

and H. Noguchi .......... ........................... ... 186

RESULTS OF SEDIMENTATION AND ELUTRIATE TESTS FROM OSAKA BAY SEDIMENT'

by H. Kosasa, K. Nikaido, and M. Natori .... ............... ... 211

PARTIAL REVIEW OF DREDGED MATERIAL DISPOSAL TECHNIQUES'

by H. Koba and M. Miyake ........ ...................... . 222

LIME-CEMENT HARDENING OF VERY SOFT FRESHWATER CLAY by M. Kamon . . . 237

DEWATERING OF BOTTOM SEDIMENTS by Z. Yoshino, K. Sato,

H. Okajima, F. Kodama, S. Taguchi, R. Sudo, and M. Okada .... . . 249

FLOW PROCESSES OF A CUTTERHEAD DREDGE'by L. S. Slotta ..2. ...... 262

SELECTION AND MANAGEMENT OF A NEW OCEAN DREDGED MATERIAL DISPOSAL SITE

AT COOS BAY, OREGON, TO RECEIVE CONTAMINATED DREDGED MATERIAL'

by J. R. Reese ........... ........................... ... 277

WASTEWATER TREATMENT BY SOIL by T. Tanimoto .... .............. ... 300

IN SITU STREAM WATER CLARIFYING TESTS'

by M. Tanimoto and T. Yoshida .................... 318

PURIFICATION OF NHO RIVER BY THE GRAVEL CONTACT METHOD*

by M. Kobayashi and T. Kiriku ....... .................... ... 328

2

. . . . . . . . . . . . . . . . . . . .
Paste

PRINCIPLES AND PRACTICES FOR THE OCEANDISPOSAL OF DREDGED

MATERIAL - THE LONDON DUMPING CONVENTION RE;EXAMINED'

by H. R. Haar, Jr ................... ............... . 357

PROGRESSIVE TRENCHING USING A SCRAPER DIGGER:by T. Inoue . ....... .. 368

ENVIRONMENTAL CONSERVATION IN THE PORT OF MAIZURU'j~ T. Matsuoka . . . 380

THE MUSSEL WATCH PROGRAMVMONITORING THE LONG-TERM EFFECTS OF DREDGED

MATERIAL DISPOSAL IN__iW ENGLAND WATERS'

by R. C. Semonian and C. J. Lindsay ..... ................. ... 398

ENVIRONMENTAL AND WATER QUALITY OPERATIONAL STUDIES (EWQOS) -

APPLICATION TO LAKE RESTORATION.by J. L. Mahloch .. .......... . 403

3:- 

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,--.;.... -.-;, :. ,,-, -...........- j....- ",,.-,.,,-, .- ; .-.L, ,. - .. ..,. . ..- .. -. -. .' -" .- ."..'-. ,". ."., -. . " ."..-- . " .'.-
ATTENDEES

10th ANNUAL MEETING

U.S./JAPAN EXPERTS MEETING

U. S. Delegation

COL George R. Kleb U. S. Co-Chairman, Corps of Engineers, Water

Resources Support Center

Mr. W. Frank Bohlen Associate Professor, Department of Marine

Sciences, University of Connecticut

Mr. Jack H. Clifton Japan District, Corps of Engineers

Mr. Charles C. Calhoun Program Manager, Waterways Experiment Station,

Corps of Engineers

Mr. Norman R. Francingues Chief, Water Supply and Waste Treatment Group,

Waterways Experiment Station, Corps of

Engineers

Mr. Herbert R. Haar Jr. Assistant Port Director, Port of New Orleans

Mr. Jerome L. Mahloch Program Manager, Waterways Experiment Station,

Corps of Engineers

Mr. James M. Mansky Assistant Chief, New York District, Corps of - Engineers

Mr. Thomas Patin Assistant Program Manager, Waterways Experiment

Station, Corps of Engineers

Mr. James R. Reese Environmental Specialist, Portland District,

Corps of Engineers

Mr. Richard C. Semonian Chief, Dredged Material Management Section, New

England Division, Corps of Engineers

Mr. Larry S. Slotta President, Slotta Engineering Associates, Inc.

Mr. Patrick M. Tobin Director, Criteria and Standards Division,

U. S. Environmental Protection Agency -

Mr. Sachio Yamamoto Head, Environmental Science Division, Naval -

Ocean Systems Center

.'% .'

'.* --. , == === ========== 4 "4. - .
Japanese Delegation

Mr. Shunich Onodera Director-General of the Ports and Harbours

Bureau, Ministry of Transport (MOT)

Mr. Teiichi Aramaki Vice-Governor of Kyoto Prefecture

Mr. Takao Hirota Director General of Port and Harbour Research

Institute, MOT

Mr. Terumi Iijima Director-General of the 3rd District Port

Construction Bureau, MOT

Mr. Ikuhiko Yamashita Director, Environment Division, Ports and

Harbours Bureau, MOT

Mr. Toshio Ikeda Environment Division, Ports and Harbours Bureau,

MOT

Mr. Takeshi Horne Port and Harbour Research Institute, MOT

Mr. Ryuji Nakamura Engineering Deputy Director General of the 3rd

District Port Construction Bureau, MOT

Mr. Morito Kawaguchi Senior Officer for Environmental Technology of

the 3rd District Port Construction Bureau, MOT

Mr. Tsutomu Fukude Director of the Environmental Protection Section

of the 3rd District Port Construction Bureau, . .

MOT

Mr. Tomio Sasaki The 3rd District Port Construction Bureau, MOT

Mr. Hitoshi Noguchi The 3rd District Port Construction Bureau, MOT - -

Mr. Toshiyasu Uno Director of the Kobe Port Construction Office,

MOT

Mr. Masashi Kamon Associate Professor, Department of Civil

Engineering, Kyoto University

Mr. Ryuichi Sudo Laboratory of Freshwater Environment, National

Institute for Environmental Studies

Mr. Masaaki Hosomi Laboratory of Freshwater Environment, National

Institute for Environmental Studies

Mr. Mitumasa Okada Laboratory of Freshwater Environment, National

Institute for Environmental Studies

Mr. Hiroshi Nakanishi Professor, Department of Civil Engineering,

Yamaguchi University

5

% .0 . o .
Mr. Motoshi Fujiki Professor, Institute of Comunity Medicine,

Tsukuba University

Mr. Ataushi Yamada Professor, Department of Science and

Engineering, Ritsumeikan University

Mr. Akira Kawai Professor, Department of Fisheries, Kinki

University

Mr. Susumu Kavashima Professor, Osaka Institute of Technology

Mr. Genta Uno Professor, Osaka Institute of Technology

Mr. Ivao Takada Osaka Institute of Technology

Mr. Zenya Yoshino Professor, Science University of Tokyo

Mr. Tadashi Tanimoto Director, Seacoast Division, River Bureau,

Ministry of Construction

Mr. Masanori Kobayashi Kanto Regional Construction Bureau, Ministry

of Construction

Mr. Fumio Kodama Kanto Regional Construction Bureau, Ministry

of Construction

Mr. Hasaharu Taguchi Kanto Regional Construction Bureau, Ministry

., of Construction -o"*

Mr. Koji Tsuchinaga Osaka City Institute of Public Health and

Environmental Science

Mr. Hiromi Koba Japan Dredging and Reclamation Engineering

Association

. Mr. Michio Miyake Japan Dredging and Reclamation Engineering

Association

Mr. Kozo Furuya Japan Dredging and Reclamation Engineering

Association

Mr. Hiromichi Yamashita Japan Dredging and Reclamation Engineering

Association

Mr. Makoto Natori Japan Sediments Management Association

Mr. Tatsuo Yoshida Japan Sediments Management Association

* Mr. Kiyoshi Nikaido Japan Sediments Management Association

Mr. Takahiro Inoue Japan Sediments Management Association

Mr. Ikuo Sakamoto Japan Sediments Management Association

6 I %
Mr. Tosbihide Mishima Japan Sediments Management Association

Mr. Yoji Kurimoto Japan Sediments Management Association

Mr. Masahiro Tagava Coastal Development Institute of Technology

Mr. Shingo Kato Vice-Councilor, Civil Engineering Department,

Mie Prefecture

Mr. Shoichi Hamaguchi Director of Governor of Minamiise District, Mie

Prefecture

Mr. Minoru Tomita Director of Civil Engineering and Construction

Department, Kyoto Prefecture

Mr. Tamaki Matsuoka Director, Port and Harbour Division, Kyoto

Prefecture

Mr. Masato Yasul Chief Editor, Port and Harbour Division, Kyoto

Prefecture

"- -'. -

7

-.. . . . . . . . .

.° N .... "% .V *-
AGENDA

10th U. S./JAPAN EXPERTS MEETING ON MANAGEMENT .

OF BOTTOM SEDIMENTS CONTAINING

TOXIC SUBSTANCES

Kyoto, Japan

30-31 October 1984

Tuesday, October 30, 1984 -

8:30-9:00 Welcoming Remarks

8:30-8:40 Director-General of the Ports and Harbours Bureau, Ministry of

Transport

8:40-8:45 Vice-Governor of Kyoto Prefecture

8:54-8:50 Director-General of the 3rd District Port Constructicn Bureau,

MOT .. 1

Chairman Kleb

8:50-9:00 Chairman Yamashita

9:00-9:30 "Legal System and Works for Preservation of the Port, Harbour,

and Marine Environment in Japan" by Toshio Ikeda, Ports and

Harbours Bureau, MOT

9:30-10:00 "United States Environmental Protection Agency's Program for

Managing Contaminated Sediments in the Environment" by

Patrick M. Tobin, Criteria and Standards Division, U. S.

Envirormental Protection Agency

10:00-10:30 "A Model of Nitrogen Release from Bottom Sediments" by Masaaki

Hosomi, Laboratory of Freshwater Environment, National

Institute for Environmental Studies

10:30-11:00 "Study on Phosphorus Behavior Between Sediment and Upper Water"

by Hiroshi Nakanishi, Dept. of Civil Engineering, Yamaguchi

University, Japan

11:00-11:30 "Evaluation of the Factors Governing the Mobility of Dredged

Material Placed at Open Water Disposal Sites" by W. Frank

Bohlen, Department of Marine Sciences, University of

Connecticut

8

°.- ,., -. ... * ,... °.,............. .
11:30-12:00 "Environmental and Water Quality Operations Studies (EWQOS)

Application to Lake Restoration" by Jerome L. Mahloch,

Waterways Experiment Station, Corps of Engineers

12:00-13:30 Luncheon (Sponsored by Vice-Governor of Kyoto Prefecture)

13:30-14:00 Movie

14:00-14:30 "Numerical Prediction on the Effect of Phosphorus Release

Control by Sediment Dredging" by Takeshi Hore, Port and

Harbour Research Institute, Ministry of Transport

14:30-15:00 "Ecological Evaluation of Organotin Contaminated Sediments" by L

Sachio Yamamoto, Environmental Science Division, Naval Ocean

Systems Center

15:00-15:30 Coffee Break

15:30-16:00 "Characterization of Sediment Contamination Utilizing

Bioassay/Bioaccumulation Testing" by James M. Mansky, New

York District, Corps of Engineers

16:00-16:30 "Identification of Promising Concepts for Treatment of

Contaminated Sediments" by Norman R. Francingues, Waterways

Experiment Station, Corps of Engineers

16:30-17:00 "The Influence of Accumulating Organic Sediment on the Seawater

Environment in Osaka Bay" by Hitoshi Noguchi, The 3rd

District Port Construction Bureau, Ministry of Transport

17:00-17-3i "Results of Sedimentation and Elutriate Tests from Osaka Bay

Sediment" by Kiyoshi Nikaido, Japan Sediments Management

Association, Joint Research with the 3rd District Port

Construction Bureau, Ministry of Transport

18:30-20:30 RECEPTION

Wednesday, October 31, 1984

8:30-9:00 "Partial Review of Dredged Mud Disposal Techniques" by Hiromi

Koba, Japan Dredging and Reclamation Engineering Association

"Lime-Cement Hardening of Very Soft Freshwater Clay" by Masashi °9:00-9

Kamon, Department of Civil Engineering, Kyoto University

9:30-10:00 "Dewatering of Bottom Sediments" by Zenya Yoshino, Science

University of Tokyo

10:00-10:30 "Dredge Cutterhead Flow Processes" by Larry S. Slotta, Slotta

Engineering Associates, Inc.

10:30-11:00 "Selection and Management of a New Ocean Disposal Site at Coos

Bay, Oregon, to Receive Contaminated Dredged Materials" by

James R. Reese, Portland District, Corps of Engineers

9
v-in

11:00-11:30 "Wastewater Treatment by Soil" by Tadashi Tanimoto, River

Bureau, Ministry of Construction

11:30-12:00 Movie

12:00-13:30 Luncheon I2.

13:30-14:00 "In Situ Stream Water Clarifying Tests" by Tatsuo Yoshida,

Japan Sediments Management Association (Joint Research with

Civil Engineering Research Institute, Ministry of

Construct ion) '"

14:00-14:30 "Purification of the Nho River by the Gravel Contact Method" by

Masanori Kobayashi, Kanto Regional Construction Bureau,

Ministry of Construction

14:30-15:00 "The Mussel Watch Program/Monitoring the Long-Term Effects of

Dredged Material Disposal in New England Waters" by

Richard C. Semonian, New England Division, Corps of Engineers

15:00-15:30 Coffee Break .

15:30-16:00 "Principles and Practices for the Ocean Disposal of Dredged

Material-The London Dumping Convention Re-examined" by ,'.".'

Herbert R. Haar, Jr., Port of New Orleans, New Orleans, .-

Louisiana

16:00-16:30 "Progressive Trenching Using a Scraper Digger" by Takahiro

Inoue, Japan Sediments Management Association

16:30-17:00 "Environmental Conservation in the Port of Maizuru" by Tamaki

Matsuoka, Construction Department, Kyoto Prefecture

17:00-18:00 DISCUSSION AND CLOSING SESSION

(Joint Communique)

18:30 RECEPTION

-.

-* . .. . . . . . . .. . . . . . .
-7- 77 W1 -1,97TI _.1

JOINT COMMUNIQUE

The tenth meeting of experts pursuant to the Agreement Between the

Government of the United States of America and the Government of Japan on

Cooperation in the Field of Environmental Protection was co-chaired by Z.Z..,..

Colonel George R. Kleb, Commander and Director, Water Resources Support

Center, U.S. Army Corps of Engineers, and Mr. Ikuhiko Yamashita, Director,

Environment Division, Ports and Harbours Bureau, Ministry of Transport, Japan.

The purpose of the meetings conducted under this agreement is the exchange of

information in regulatory, technical, and operational areas relevant to

management of bottom sediments and exploration of areas where joint effort

appears fruitful.

Experts from both countries presented technical papers on a variety of

subjects including legal and research programs to evaluate and protect the -

marine environment. More specifically, subjects included evaluating and predicting the behavior of nutrients, organics, and contaminants in dredged sediments and identifying and evaluating the many alternatives to dredging and

disposing of contaminated sediments and waters associated with these sediments. Management practices with the most promising long-term utility were

emphasized.

This tenth meeting was highly successful and fruitful. The information

exchange was very effective. The conference attendees generally agreed that

the dredging technology and sediment management programs of both countries

will significantly benefit. The Co-Chairman agreed that the next meeting will

be in the United States in 1985 and that the date will be decided jointly.

Director, Environment Division Commander and Director, Water Resources

Ports and Harbours Bureau Support Center, U.S. Army Corps of

Ministry of Transport Engineers

!kuhi*Y-?amashita Col. G e R b" " '"2"

October 31, 1984 October 31, 1984

. . . . . .. . . . . . . . .
- L .~-. -- V IAw b fi ------- Y .. . is. .. Z . M X_1. _0' -3i 7- -%- .; 21-- 7".'r a 71W U;F .- ~ .

LEGAL SYSTEM AND WORKS FOR PRESERVATION OF THE PORT,

HARBOUR, AND MARINE ENVIRONMENT IN JAPAN

T. Ikeda

Environmental Division, Ports and Harbours Bureau

Ministry of Transport

JAPANESE ENVIRONMENTAL CONDITIONS

Environmental pollution in Japan progressed rapidly during the period of

high economic growth beginning in 1960. In response to strong social demand

for the prevention of pollution, pollution control measures progressed rapidly

in the 1970s and the worst cases of environmental pollution were eased. The

conservation of energy and resources also progressed while the economy shifted

• .from high growth to stable growth. Today, environmental pollution is graduolly lessening.

This paper will outline the current situation of water pollution in

Japan. The situation of water pollution can be expressed by the rate of *..-

achievement of environmental water quality standards (health items and living

environment items).

As for health items, the results of measurement of water quality in public marine areas in FY 1982 show that the proportion of samples not meeting

the environmental quality standards (percentage of nonconformity) was 1.4% in

FY 1970 but decreased to 0.3% in FY 1982, thereby showing a considerable improvement (Figure 1).

1.3

0.; %

Figure 1. Percentage of noncon- o :'

formity of the

environmental water 0A h

quality standards on

health items . 02 -•- .".o

70 71 72 1 14 7$ 76 77 76 8i 2 FY)

As for the living environment, 67.5% of the marine areas achieved the

environmental quality standard for the typical water quality index of biochemical oxygen demand (BOD) or chemical oxygen demand (COD). In detail, _r--

81.3% of the sea areas, 65.3% of the rivers, and 41.7% of the lakes achieved

the quality standard. Even though the sea areas achieved a better quality

12

. . '

,. -#,..,,' .. . . * * . .. . ..** . . . . . • , , - , . . ,., , - . . . - . . * .- . . . ,- , . , . . . . -

" ., . .. " 4 ..." m_ f K: " LI -' i." .L'. . "-,.' * . "." --. .. , _ . '--. . . . " . . . _.. . '- *- "--' .. .
standard than the other marine areas and the water quality of sea areas tends

to improve (Figure 2), the water quality is still at a low level in Tokyo Bay,

Ise Bay, and other areas where the seas are mostly closed and large pollution

sources exist in the hinterland (Figure 3).

CE too i

10 90

2D Sea Areas Total Sea Areash

go.ar 5*to 18n

70 . . . . . ..... 70 T" a

so

74 7 76 77 78 79 80 81 82(FY) 74 73 76 77 78 79 60so 8 2 (FY) --.

Figure 2. Rate of achievement Figure 3. Rate of achievement i

of the environmental of the environmental

water quality stan- water quality stan- .- . dards on the living dards (COD) in large i: :!

environmental items closed sea areas

LEGAL SYSTEM FOR THE PRESERVATION OF THE PORT, HARBOUR, AN~D -

MARINE ENVIRONMENT

Twenty anti-pollution laws were established during the 6-month session of --.-"

the Diet beginning in late 1970 which was called the "Anti-pollution Diet." ,-.'-

Thereafter, various additional laws were formulated and many legal restric-""- "'

tions enacted. The legal system covering the environmental conservation of

ports, harbours, and marine environment (Figure 4) will be discussed below.

Pollution Control (Established 1967) ,?.

Contents of the Law

This is the basic law for various laws and regulations related to pollu- "

tion in Japan. Its purpose is to comprehensively promote anti-pollution mea-".""

sures, protect the public health, and conserve the living environment. To ,-..

achieve this purpose, the following items are prescribed: (1) items for clar-

,lIying the responsibility of enterprises, the Government, and local public:-..."

bodies for the prevention of pollution; (2) basic items related to measures _

for the prevention of pollution; (3) items related to the bearing of costs and "-"

financial measures; and (4) items related to the Conference on Environmental .. i

Pollution Control and the Council for Control of Environmental Pollution. :'

Substantial restrictions and measures are executed based upon the individual '-'.'

laws established for the fulfillment of the basi.c law, except the establish- ,

ment of environmental quality standards for the unification of policies (Arti-

" ~cle 9) and the preparation of an environmental pollution control programme ..,.. (Article 19), which are covered below

. . ........ ..... . . . ... . . . .. , ¢.

"" " "-,.. W.'_- , 4 78 7 D.8 F)7 -5 7 7 879 8 1 2(Y -6 
Basic Law of Environmental

Pollution Control

Bearing of the Cost Law Concerning Enterpreneurs' Bearing

of the Cost of Public Pollution Control Works

Law Concerning Special Government Financial

Measures for Pollution Control Project

lWater Pollution Water Pollution Control Law

Seto Inland Sea Conservation Law

The Law relating to the Prevention of Marine .

Pollution and Maritime Disaster

Waste Disposal and Public Cleansing Law

e Waste Disposal and Public Cleansing Law

L Interprefecture Coastal Area Environment

Improvement Center Law

Port and Harbour Port and Harbour Law

Facilities

Figure 4. Legal system for the preservation of the ports,

harbours, and marine environment in Japan

Establishment of Environmental Water Quality Standards

These standards are the targets for the water quality preservation administration and were established as desirable standards to be maintained for the

water quality of public marine areas such as sea areas, rivers, and lakes.

They comprise the standards for protecting the people health (health items)

and the standards for preserving the living environment (living environment

items). For the health items, nine substances harmful to public health were

uniformly established for all public water areas. However, for the living

environment items, the types of water areas were established by water utilization for rivers, lakes, and sea areas, and standard values for items such as

BOD, COD, and dissolved oxygen (DO) were established for each type of water

body. Thus, the environmental quality standard for the relevant public water

body can be firmly established by designating the type of water body.

Preparation of Environmental

Pollution Control Programme

This programme is formulated in accordance with Article 19 of the Basic

Law for Environmental Pollution Control for areas where considerable pollution

already exists or areas where the pollution is likely to continue to worsen

due to the high concentration of people or industry and the pollution cannot

14V.

* 4 "=*" 

°

"-

".. -. .. '. -
be controlled unless comprehensive measures are taken. The first of these

areas was recognized in FY 1970, with several additional areas recognized sequentially thereafter; the seventh such area was recognized in FY 1976. Since

then programmes have been reexamined, integrated, and abolished. Today there

are programmes for 46 areas in Japan, and environmental pollution control pro- ,..

grammes have been prepared for all major metropolitan areas and industrial

cities across the country (Figure 5).

Law Concerning Enterpreneurs'

Bearing of the Cost of Public Pollution Control Works (Established 1970)

This law was established to enact Article 22 of the Basic Law for Environmental Pollution Control which obligates corporations to share the burden

of all or part of the cost of works conducted by the Government or local public bodies for preventing pollution expected from the operations of the corporations. This law sets forth the details concerning the burden of costs of

the pollution prevention works to be shared by the corporations. The law

states that a corporation is obligated to share the burden of all or part of

the cost of pollution prevention works, the total cost depending upon the

degree of pollution considered to be created by the corporation's operating

activities. The costs cover dredging for pollution prevention, earth borrowing for polluted agricultural land, and forming buffer green tracts. From the

enactment of this law to the end of 1982, this law was applied to 62 cases of

* pollution prevention works. The total cost of the pollution prevention works

was about V136,300,000,000, and the total amount borne by corporations was

about V68,100,000,000; the average percentage of costs borne by corporations

was 50.OZ.

1 4a

¢~~: .'."-.- Figure a 5. ,,of. F -.---t.,l to.n

, , ' ',, . : ., . *

* \ f " '", 0J.;, ....

Okanama e . 

* l°

Figure 5. Formulated areas of Environmental Pollution ..-.-

Control Programmes (Continued)

15 %%

. .*. . . . . . .

•- . . . . . ... . *.:*=:o . - . . % ..
First Areas Pr.Y778ihr2 FYI9--8

Toakoemi Area

Yokkaichi Area 9 Sendaiwan Area

slizashima Area t Iwaki Area

Coastal Chiba Arts -

ToyamaTakaoka Area

f Kinuars" Western Milkaw Area

Kobe Area

/FY72-76 B ingo Area Second Areas IFY77-41 I Shuman Area

k FY82-864 / Tomyo Area

it Renge" Area

Osaka Ares

Ck Saitama Arets ,xth Area. ( FYT5-7

it Kyoto Arta Y794

(1, Nars YaMato Valay

Nfuroran Area

.Haehinebe Arta

SNiigata Area

Shizvoka, Shimisu Area

Fj 8 17 Wakayama AreaI ..

Third Areas FY77 Okayama-Bilen Area

FYS2 9 Hiroshima -Kure Area

SSbimonoseoki-Ubo Area

Kashima Area 4 Kagawa Area '-.'.-

Nagoya etr. Area

EasternArea of HKolo PrefeCtur"

Si ta -Kyushu Arte m Oita Ares

Seventh Area F 18 )

- 9 Sapporo Area

frY? 37, I Akita Area

Fourth Areas (l'781 62 Hitachi Area

FY3-7 / % Matsuroto-S., Area

:. GifuOgsiki Area

Fuji Area a To.o Area

V SoJthern Hr:ra Ares -4 Eastern Mikawa Area

Otake Area I Tokushima Area

I lskuni Area Hyug *.obeoks Area

3 i),ts Area

-

Figure 5 (Concluded) %

16

** 4 . . . . ... . -.-
* -~ ' . %= -% ', . - ., 7.. -. . %.r 0

Law Concerning Special Government

Financial Measures for Pollution

Control Projects (Established 1971)

Past financial measures by the Government for pollution prevention were

not necessarily sufficient, and because of this, the above law was established

to clarify the financial responsibility of the Government and to further promote anti-pollution measures by local public bodies.

This law applies mainly to areas covered by the environmental pollution

control programmes set forth in Article 19 of the Basic Law for Environmental

Pollution Control. This law also details the special measures related to th,-

shares of government subsidies, local government securities, and subsidy

taxes. The shares of government subsidies give 50% aid (burden) instead of

the ordinary ratio of aid (ratio of burden) for all dredging, water conveyance, and works of installation of waste disposal facilities related to the

ports and harbours. Special measures for local government securities are intended to expand these works to give preferential treatment for work to which

"* special ratios of burden and aid of the law have been applied.

." Water Pollution

Control Law (Established 1970)

This law was established to protect the public health and conserve the

living environment by properly maintaining the water quality in public marine

areas by restricting the discharge of water from factories, etc.

Effluents to be Restricted

Effluent from factories and places of work ("specified places of work")

where "specified facilities" are installed in the public marine areas such as

rivers, lakes, ports and harbours, and coastal sea areas is restricted by this *

law.

The "specified facilities" are the facilities so designated by Cabinet

Orders which discharge wastewater or liquids containing harmful substances or ..

substances that are likely to cause damage to the living environment. The

facilities of 91 types of industry have been already designated as specified

facilities.

Eff.lent Standards

Effluent standards are the allowable limits established for each pollution index with respect to the existing pollution of the effluent in order to

restrict the effluents from the specified places of work. There are three

types of standards as shown below.

Uniform effluent standards. Uniform effluent standards have been established by the Government in the form of maximum values as a rule for harmful

substances such as cadmium and cyanogen and for items such as pH, COD, and

BOD, and are uniformly applied to all the specified places of work.

Strict standards. For marine areas for which the environmental quality

standards cannot be achieved or maintained by the uniform effluent standards

17

.. , .......... .- ,.'.',..'..*-'..... . .*. * -. *. . .. ... ",, . .','
% " +.1 , *

alone due to natural and social conditions, the prefectural governments can

establish more strict standards by means of prefectural ordinances. All the

prefectural governments established these strict standards after FY 1975.

Standards for regulation of total emission. In public marine areas with

a large volume of effluent resulting from the high concentration of people and

industries, it is difficult to achieve the environmental quality standards by

uniform effluent standards or strict standards alone. In these areas the

standards for the regulation of total emission are established. Standards for

the regulation of total emission have been established for Tokyo Bay and Ise

Bay in accordance with the total emission reduction plans formulated by the ,.

relevant prefectural governments in response to the basic policies for reducing total emission concerning COD established by the prime minister in June .

1979. Measures for reducing the COD emission are now being taken.

Seto Inland Sea

Conservation Law (Established 1978)

Though the Seto Inland Sea has favorable natural conditions, water pollution developed quickly since it is a closed water area with a high concentration of people and industry in the nearby areas. %

Therefore, the "Extraordinary Seto Inland Sea Conservation Law" was established in 1973. However, in 1978 new measures were added to this law and

it was revised to "Seto Inland Sea Conservation Law." This is a special law

of the Water Pollution Control Law that promotes the following environmental

conservation measures:

(1) Relevant prefectural governments are required to make environmental

conservation plans in accordance with the Basic Plan for the Environmental Conservation of Seto Inland Sea (established by a Cabinet

conference in April 1978). The relevant prefectural governments

formulated the conservation plans in July 1981. -'

(2) When installing the specified facilities set forth in the Water

Pollution Control Law, an environmental influence assessment is required, and the installation must be approved by the appropriate

governors.

(3) A system regulating the total emission of COD not only for indus- 7.

trial effluent, but also for household effluent is prescribed (the

mechanism of the system is prescribed in the Water Pollution Control

Law). The relevant prefectural governments formulated the total

emission reduction plans in March 1980 (target year: FY 1984).

(4) The Director of the Environment Agency ordered the formulation of

measures against eutrophication In July 1979. The relevant prefectural governments accordingly formulated the reduction guidance pol- . -.

icies for phosphorus and its compounds in April and May 1980 (target

year: FY 1984).

18

".-.. ....................... •.••.....................° .-
(5) Natural beach areas that can be used for recreation such as sea

bathing now and in the future were designated as natural preservation areas. Various activities are permitted there with proper

prior notification.

(6) The perculiarities of the Seto Inland Sea must be considered when .'-,

approving reclamation work (basic policies to be considered by the

relevant prefectures were established in June 1974). .

Law Relating to the Prevention of Marine Pollution and

Maritime Disaster (Established 1970)

This law ensures the proper disposal of waste oil by restricting the discharge of oil and waste from ships. This restriction prevents marine pollution and maritime disasters by taking proper measures against discharged oil

and wastes, and thereby conserves the marine environment and protects people's

lives, health, and other assets. This law has been revised four times to

;. respond to the international trends in the prevention of maritime pollution;

its restrictions were strengthened and new restrictions were added.,.-..

Emission of Oil from Ships

As a rule, ships are not permitted to discharge oil in sea areas. Oil

may be discharged in an emergency Pid if the effluent standards established by

tonnage and type of ship are strictly observed.

Discharge of Waste from Ships

The discharge of waste from ships in sea areas is also prohibited as a ...

rule. Discharge is permitted in an emergency and in the cases listed below if

- certain requirements are met:

a. Discharge and sewage resulting from the daily life of seamen in

ships.

b. Discharge to reclaimed land and so forth.

c. Discharge of wastes (part of sludge, sewage, cinders, etc., for which

the disposal by ocean dumping is unavoidable and thus permitted by

"Enforcement Ordinance of the Waste Disposal and Public Cleansing

Law").

d. Discharge of wastes for which the disposal by ocean dumping is

unavoidable and thus permitted.

Waste Oil Disposal Works

To ensure the proper disposal operations at waste oil disposal facilities, an approval system has been formed for these and other facilities (excluding port management bodies and fishing port management bodies). A notification system is in effect for port management and fishing port management

facilities and also for privately owned facilities.

19
w~~~~ ~ ~ ~ W"T R& vrm K7 A-r4V1V 

Waste Disposal and Public

Cleansing Law (Established 1970) ,:

This law conserves the living environment and improves the public health

by properly disposing of wastes and maintaining a clean living environment.

* Definition of Wastes

Wastes are defined in this law as discarded items such as rubbish, bulky

refuse, and cinders and are classified into ordinary waste and industrial

waste. Dredged sediment, surplus soils produced by inland construction and

radioactive wastes, etc., are not included in the wastes set forth in this law

(Figure 6).

Rubbish from Home

Rubbish

General Wastes Rubbish from Factory

Sewage C

Sewage

Wastes- Sewage Purification

Chamber Sludge

Industrial Wastes .*.? .

Surplus Soil Produced by Inland Construction

Dredged Earth and Sand

Figure 6. Classification of wastes

Method of Disposing of Wastes

Wastes may be disposed of by incineration or by disposal on a reclamation

site, but must be disposed of without polluting the living environment in

accordance with the disposal standards prescribed by Cabinet Order.

Interprefecture Coastal Area

Environment Improvement Center Law

An extremely strong demand exists today for securing coastal waste disposal sites (interprefecture coastal disposal sites shown in Figure 7) in metropolitan areas that can be used both by local public bodies and by developing

ports and harbours to support the sound development and activities of cities.

Therefore, this law was established to prescribe the foundation and scope of

work of the organization called the "Interprefecture Coastal Area Environment

Improvement Center" (hereinafter called "the Center"). Duties of the Center

20 p- .
- . -* . . V . -* . - --. --.- -.

Cleaning Factory(pwral Vastes) ".

SmmauiSur. Uuload

•"... 4

Costruction. Site

odgFail ties . L.i. F~clort, .s--

coastal Waste Dispsal Site

Figure 7. Outline of interprefecture coastal waste

disposal site

are (1) to develop bulkheads for coastal waste disposal sites commissioned by

port management bodies and to develop coastal reclaimed land on the sites by

using waste, (2) to develop final disposal facilities commissioned by local

public bodies for ordinary waste and industrial waste prescribed by Cabinet

Orders and to develop coastal reclaimed land by using these wastes, and (3) to

develop final disposal sites for industrial waste as the Center's own project

and to develop coastal reclaimed land by using these wastes. The Center is

required to formulate a master plan and an execution plan based on the master

plan for the duties stated above. Because of the nature of the work assigned

to the Center, the relevant port management bodies and local public bodies are

deeply involved in the operation of the Center, and the Government is involved

in the establishment of the Center, the preparation of the master plan, etc.

tFigure 8).

For the Osaka Bay zone, the Osaka Bay Interprefecture Coastal Area Environment Improvement Center was established in March 1982 in accordance with

this law, and this Center has been making a survey required for developing

interprefecture coastal disposal sites.

Port and Harbour

Law (Established 1950)

This law controls the orderly development and proper operation of ports

and harbours. Improvement of the port and harbour environments was amended in

1973. Because of this, port pollution prevention facilities (water conveyance

facilities, buffering 7ones for pollution prevention, etc.), waste disposal

facilities (bulkheads for coastal waste disposal sites, waste incineration

facilities, etc.), and port environment improvement facilities (beaches, green

tracts, etc.) are designated as port and harbour facilities, and legal and

financial measures necessary for the development of these facilities are being

taken.

21

,S .. °.

.. . . . . . . . . .. . . . . . . . I .. .. .. . . .
Appointment of Potential Areas of Interprefecture Coastal

Waste Disposal (Minister for Health)

Appointment of Potential Development Ports of Interprefecture

Coastal Waste Disposal Site (Minister for Transport)

P romoter %

-Formulation of the Articles of Association

LFlotation of Investment

Approval of the Establishment of the Center by the Appropriate

Ministers (Minister for Health, Minister for Transport)

]Establishment of the Center

[Formulation of a Master Plan.

Consultation

Local Public Bodies, Port Management Bodies

Approval

Appropriate Ministers

]Formulation of an Execution Plan,

Consultation

Local Public Bodies, Port Management Bodies

Submission

- Appropriate Ministers

lConstruction of Interprefecture Coastal Waste Disposal Site

Figure 8. Flowchart of interprefecture coastal waste disposal

works by Interprefecture Coastal Area Environment

Improvement Center Law

PRESERVATION OF THE PORT, HARBOUR, AND MARINE ENVIRONMENT

As part of the port and harbour improvement works, various tasks are

being carried out to preserve the port, harbour, and marine environment and to

prevent pollution. These tasks are being particularly aggressively carried ',

out since the partial amendment of the Port and Harbour Law in 1973. As shown

in Figures 9 and 10, the total project cost was V4,000,000,000 in FY 1972 and

increased to V17,000,000,000 in FY 1973, with a peak in FY 1979 of

M58,000,000,000. Today the cost tends to remain around M50,000,000,000 since

the development of bulkheads for coastal waste disposal sites in metropolitan

areas is almost completed and the financial situation is very severe. The

various kinds of work to preserve the port, harbour, and marine environment .

are outlined in Table 1 and discussed in detail below.

22-.*.-.

........... .
Cost of Pert ml Near Issrove most VUrk

4001

200

10

Cost of Works for Preservation of the

Port, HIarbour. and Marine Esvirowment

Figure 9. Project costs, FY 1972 to FY 1983

*Works to Provide Facilities for

* Preventing Oil Pollution of Seawater

The disposal of effluent oil generated by ships to the ocean is restricted

* by the law relating to the Prevention of Marine Pollution and Maritime Disasters. Waste oil reception facilities for receiving and properly disposing of

* this waste oil on land are being developed by petroleum refiners, waste oil

* disposal experts, port management bodies, and fishing port management bodies.

As of August 1984, Japan had 140 facilities in 85 ports (Figure 11). Government subsidies were offered so that the above facilities could be constructed

and improved by the port management bodies beginning in FY 1967, and subsidized projects were executed in 54 ports through FY 1983.

* Port Pollution Prevention Works

These works are performed in ports and harbours where contaminated sediments exist which may cause pollution, or where water quality would be degraded by removing the sediments. Port pollution prevention can be divided

into two sections: (a) dredging and earth covering performed in accordance

with the Law Concerning Special Government Financial Measures for Pollution

* Control Projects, (b) constructing or improving water conveyance facilities,

dust control fences, etc., performed in accordance with the Port and Harbour

Law. Government subsidies have been offered since FY 1972 to the above works

to be performed by the port management bodies, 1'id subsidized works were carried out in 30 ports by FY 1983 (Figure 12).

23

is
* ,.,# -, .. ,...-

2.

Total Cost of Works for Prosor-atloa

| of the Port. Harbour. and Maria. Mili" ila Erviroanmest

yen.

sWork to Provide Facilities I for Preentin Oil Pollutioo .

~of Seawater Port Pollution Prevntonwrical

So. M arine E..,rowaot

'Stud for Mlaterial i tion 01

PortWos*a of

lO "ND -0-- _..j -~Part Environment Imprvmnt',-

30 .- "

+ -e . ,

20-*~ % Bulkhead for Coastal

0 WastD isposal Site

10 a-- /. --- 

72 73 74 75 76 77 78 79 s0 SI 82 83

Frcal Year %

Figure 10. Costs of works for preservation of the port,

harbour, and marine environment

Port Environment Improvement Works

Bulkheads for Coastal Waste

Disposal Sites

Though measures for reducing the weight of wastes such as incineration

and recycling are being taken, there is still a large volume of waste that

requires a final disposal such as disposal on reclamation sites. Also, it is

becoming more difficult to secure final inland waste disposal sites due to

urbanization. Because of this, a strong demand exists for securing coastal"M "

waste disposal sites. In addition, more sophisticated port functions and redeveloped urban seashore areas are needed to support the sound development and

activities of the cities behind the ports. Therefore, a strong demand for

securing necessary land has arisen.

In order to respond to the social needs stated above, government subsidies have been offered since FY 1973 for the development of bulkheads for

coastal waste disposal sites by port management bodies in Tokyo Bay and Osaka

Bay. Work has begun to systematically secure the required space within ports

and to properly dispose of the wastes. By FY 1983 works of this kind were

carried out in 24 areas in 19 ports.

.- .%.. ,

24

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- .. * * * *.*. *- . .. . * . . .. - *. .c : .

* - *.*. .*. * - . . . * -*** * .. *.''.w
Facilities Such as Green Tracts

In order to secure a pleasant environment and provide recreational areas

within ports, government subsidies have been offered since FY 1973 to develop

port environment improvement facilities such as green tracts, open spaces, and

vegetation. These facilities have been developed by the port management

bodies. A gross project cost of about V69,000,000,000 has been invested

through FY 1983 and green tracts of about 520 ha have been developed.

Building Cleaning Ships

Rubbish such as refuse from rivers or articles dropped during cargo

handling in ports may float on the water in port areas and spoil the beauty of

the port or obstruct the navigation of ships. Port management bodies recover

such rubbish and some ports have cleaning ships for the efficient and quick

removal of rubbish. Government subsidies have been offered for building these

cleaning- ships for the ports since FY 1974. Seventeen ships were built

through FY 1983.

Marine Environment Improvement Works

The ocean is polluted by rubbish, oil, and other refuse flowing from

rivers. Especially severe pollution occurs in inland areas and bays that

greatly affects marine activities, living environment, marine resources, etc.

Because of this, the removal of rubbish and oil by ships in three sea ."-.

areas, Tokyo Bay, Ise Bay, and the Seto Inland Sea, for which the preservation

of marine environment is greatly needed, has been being carried out as a

-.- government project since FY 1974. ..

" Study for the Materialization of Port Works ,"

Bottom Sediment Purification

In order to drastically improve the marine environment in Tokyo Bay, Ise

Bay, and Seto Inland Bay where eutrophication has greatly progressed, it is

necessary to reduce the inflow load and decrease the elution of organic matters and nutrient salts from sludge deposited on sea bottom, thereby eliminating the vicious cycle of seawater pollution. For this purpose, the bottom

sediment must be purified by removing the sludge. In FY 1979 a government

project for examining technical problems to be solved in executing the sediment purification of Tokyo Bay, Ise Bay, and the Seto Inland Sea was begun.

Interprefecture Coastal

Waste Disposal Sites

In order to respond to the demand for the development of "interprefecture

coastal disposal sites" explained earlier, a survey required to establish the

Interprefecture Coastal Area Environment Improvement Center has been conducted

since FY 1979 as a study for the materialization of port works as a government

project.

28

- ..................... . . . . . ...- *-.-. .
In response, the Osaka Bay Interprefecture Coastal Area Environment Improve-

* ment Center was established in the Osaka Bay area in March 1982. In addition,

* a continuous study for the materialization of port works is currently being

* performed in the Tokyo Bay area.

.1~ .*.,29
A MODEL OF NITROGEN RELEASE FROM BOTTOM SEDIMENTS

M. Hosomi, M. Okada, and R. Sudo

Laboratory of Freshwater Environment

National Institute for Environmental Studies

Yatabe-machi, Tsukuba, Ibaraki 305, Japan

ABSTRACT

A multi-component dynamic model for nitrogen in

the bottom sediment-water system of Lake Kasumigaura,

a highly eutrophic and shallow lake, was developed to

obtain quantitative information on the sediment-water

interactions. The model was calibrated and the sensitivity analysis of the model parameters conducted to

identify the deficiency of our knowledge at present

and to determine future research needs. Good agreement between the model calculations and observed data

of nitrogen release flux and nitrogen concentrations

in the sediment was noted. The nitrogen dynamics of

the upper layers (0-6 cm) of the sediment seem to

regulate the nitrogen transportation between sediment

and water. Further studies on the vertical distribution of ammonification rate were found to be necessary

from the sensitivity analysis. The effectiveness of **. .

eutrophication control programs was evaluated using

the calibrated model. The reduction of nitrogen deposition rate to the sediment and the bottom sealing

were more effective than the sediment dredging for the

control of NH4-N release from bottom sediment.

INTRODUCTION

Bottom sediments are known to play an important role in the lake eutrophication process (3, 7, 11, 14). Particularly in lake restoration programs,

we cannot ignore the effects of the sediments on nitrogen and phosphorus budgets. In restoration programs, such as wastewater diversion and advanced

wastewater treatments, that have been completed, there are examples where

water quality did not improve to the desired levels because of nutrient release from bottom sediments (21, 37). In implementing lake restoration programs effectively, it is necessary to quantify the role of bottom sediments.

In this paper, a multi-component dynamic model for nitrogen in the sediment-water system of Lake Kasumigaura was developed with two purposes. The

first purpose is to obtain quantitative information on the sediment-water

interactions and to identify the deficiency of our knowledge at present and to

30 ,-

.......... ° .... . ....................... °° . °. ° - . ° - ° ....-....
determine future research needs. The second purpose is to estimate the effec- 4

tiveness of eutrophication control programs such as sediment dredging and lake i.-

bottom sealing using the calibrated model.

Nitrogen is closely related to lake eutrophication. Particularly,

nitrogen is considered to be the limiting nutrient for algal growth during the

summer in Lake Kasumigaura (33). Table I shows previous models on nitrogen

release from bottom sediments. One box model (5, 16, 33) cannot give us quantitative information on nitrogen dynamics in bottom sediments. Additionally,

one box model uses an assumed sediment thickness or volume which may be unrealistic. Previous models did not consider denitrification, whereas denitrification plays the most important role in nitrogen budget in shallow lakes (3).

Although some studies presupposed steady-state for NH -N and NO -N profiles in

4 3

the sediments, it is well known that nitrogen concentration in the sediments

shows seasonal changes, especially in shallow lakes. Previous models as shown

in Table I were not used for the objective of estimating the effectiveness of

eutrophication control programs.

The proposed model for nitrogen dynamics in the sediment-water system

includes not only nitrogen transformation processes such as ammonification,

nitrification, and denitrification, but also nitrogen transportation processes

such as diffusion, sediment accumulation, and compaction, thereby enabling us

to predict the seasonal changes of the release flux of NH4 -N and NO4° 2 2 + NO 3 - N .

(NOx-N) at the sediment-water interface and the vertical distributions of

NH -N and NO -N in the pore water, and particulate organic nitrogen (PON)* in 4 X

the sediments.

MATERIALS AND METHODS

The model was developed for Lake Kasumigaura, the second largest lake in

Japan. The lake is highly eutrophic. Annual mean concentrations of total

nitrogen and total phosphorus are 1.5 mg I- and 0.09 mg I- , respectively. -3 -pIn summer, chlorophyll-a concentrations often exceed 200 mg m . The lake .-' 2 consists of four basins with a total surface area of 171 km with a mean and

maximum depth of 3.9 and 7 m, respectively. The study station shown in Figure I is 6 m deep. In this study, NH4-N and NO -N release fluxes were esti- . - x mated at this station during 1981-1984 by the laboratory sediment core method

and mathematical model method used by Hosomi et al. (15). At the same time

(1980-1982), NH4-N and NO -N concentrations in interstitial water of the x sediments (12), PON in the sediments (unpublished data), and limnological data

in lake water (2) were measured.

A numerical procedure by the Runge-Kutta-Gill method was employed to

solve the differential equations to define the model (HITAC M-150, Computer %

Center, National Institute for Environmental Studies) using t - 0.02 days. -"

• For convenience, symbols and abbreviations are listed in the Notation.

31

* . .... . . . . . . . . . . . . . . . .
II

TABLE 1. PREVIOUS MODELS ON NITROGEN RELEASE FROM BOTTOM SEDIMENTS

State

Researchers Variable Structure Process

Chen & Orlob (5) Organic Box model Deposition of detritus and

Park et al. (33) sediment (1 layer) phytoplankton, release r. w

by decay (Ist order) of

organic sediment

Nyholm (27) Release rate - a x

(deposition rate)

a; constant; that is,

release rate is proportional to deposition

rate

Jorgensen (16) Nitrogen in Box model Deposition of detritus and

sediment (I layer) phytoplankton, release

(PON) rate - b x (nitrogen

concentration in

sediment), empirical

model

Ukita (35) BDN, NH4-N Box model Deposition of detritus and

(20 layer) phytoplankton, mineralization of BDN, diffusion

of NH 4-N

44

*Kamiyama (18) PON, NH4-N Analytical Sedimentation process, '::::[

model generation rate of

(steady- NH4-N, adsorption, -

state) diffusion of NH4-N

Vanderborght, NH -N, NO3-N, Analytical Ammonification, nitrificaWollast, and 2 o model tion, denitrification,

Billen (36) (steady- diffusion of NH -N,

state), NO3-N, and 02 4

two layer N 3 N

mass

transfer

model

32

., 

-

•~~~~~~~~~~~~~~~~~~~ . o , = •° = .o • . ° . . . ' .o - .. -.. . . . . .- . . . . . .. . . .
-- .- S - .-- -v - - - -! . - . - . - . -

ha Ilr

skoy. Tsuchiuralrl,.,- Lake Cent

St.9

Figure 1. Study station in Lake Kasumigaura

MODEL STRUCTURE

The proposed model in this study consists of homogeneous overlying water

and the sediment divided into 20 layers along the depth with the thickness of. -

1 cm. The model includes transformation processes of nitrogen compounds and

sedimentation processes.

w Sedimentation Process

Assumptions to formulate sedimentation processes are as follows:

a. The sediment consists of pore water and solid sediment.

b. Deposited materials from the overlying water form the solid sediment.

c. The volume and density of solid sediment are conserved in sedimentation processes.

d. The porosity at a definite depth does not change with time.

e. Porosity decreases with depth by sediment compaction and levels off

at the specific depth.

Sediment accumulation by continuous deposition of particulate matter at

the top layer of the sediment causes the sediment-water intcrface to move

upward in reference to a fixed datum. In addition, sediment compaction due to sr

sedimentation processes induces the advection of pore water. In order to

adjust this moving interface, the space coordinate system in the model was

33 -S.

5.~**..." . .'
transformed to move with the interface so that the sediment characteristics '

are observed relative to the interface (z = 0). As a result, a velocity term J,\J;.

is introduced in the sediment equations which represents the relative motion

of the sediment with respect to the interface. We call this velocity term

sedimentation rate. Naturally advection induced by compaction is also

"" affected by the sedimentation rate.

th Volumetric balance of solid sediment and pore water of the i layer in

the sediment was established based on the assumptions a, b, and c. From

assumption d, sedimentation rate of the ith layer, Si , is:

si = ss( - i) (1) ;:

In the depth where porosity approaches its ultimate value, advection

velocity of pore water by compaction approaches zero (assumption e). Then,

the following equation is obtained:

AVi [1/(1 - *i) - 1/(1 - *.)lJfss (2)

From Equations 1 and 2, the net velocity of pore water is: "

SW- .fss/ - ) (3)

Nitrogen Kinetics

Major transformation processes of nitrogen compounds in the sedimentwater system are as follows:

a. Deposition of PON in the overlying water to the top layer of the

bottom sediment.

b. Ammonification based on the decay of PON in the sediment.

c. Adsorption equilibrium between dissolved NH4-N in the pore water and

adsorbed NH -N onto the solid sediment phase. 4

d. Nitrification of dissolved NH -N in the pore water.

4

e. Denitrification of dissolved NO -N in the pore water.

f. Diffusion of dissolved NH -N and NO -N in the pore water along

concentration gradients. ,

Both nitrogen transformation processes mentioned above and sedimentation

processes are incorporated into the model. Figure 2 is a schematic diagram of

the structure of the model.

Sedimen~tation flux of PON in the overlying water to the top layer of the

sediment is obtained by multiplying PON concentration in the overlying water

with deposition rate VN of PON in the overlying water. PON in the overlying

water is expressed as forcing functions. PON cannot be decomposed completely (31). A fraction, 1-E, of PON is not attacked by bacteria.

34

. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. .
Z~~~~~~~~ ~ V. ... 1_7 7 .II73

WATERPO

I- E E NH4 -N NOx- N

ompatio dpoiton dif fusion diffusion

SEDIMENT NH4-Nftaio nitifcaio

1st Layerdesor'ption

~A

fictin io

Fi of idni*ifottio

2nd Layer . -Aw 

20th Loyer

Figure 2. A schematic diagram of the structure of the model

proposed

PON in the sediment can be divided into biodegradable nitrogen (BDN) and

* -,table nitrogen (SN) (12, 35). The former is mineralized, while the latter is

*not. Ammonification in the sediment is caused by mineralization of BDN. This

* process was simulated as the first-order reaction. BDN is defined from the 3 vertical distribution of PON in the sediment as shown by the hatched area in

35
,: . .-..

Figure 3. Ammonifying bacteria decrease exponentially with the depth of

sediments (13, 20). Ammonification rate is also strongly dependent upon

temperature. Ammonification rate in the ith layer g, is:

T-30

g3 0 "BDNi.eg exp(-a" i) (4)

PON (mgN g dry sediment)

05 10

AK

a

C~" 10- N ".

20-

Figure 3. Vertical distribution of PON (SN(A) + BDN (B))

in the sediment in Lake Kasumigaura

Figure 4 shows a relationship between NH4-N concentration in dissolved

form and in adsorbed form in the sediments in Lake Kasumigaura. A similar

simple relationship was confirmed in Lake Biwa (19) and Lake Suwa (25).

th

Adsorbed NH4-N onto the solid sediment phase of the i layer in the sediment

q can be expressed by NH4 -N concentration in the pore water:

qi = KNHi (5) i

Ammonium nitrogen is transformed to nitrate in a series of bacteriamediated oxidation reactions within the sediments superimposed by oxygenated

water. Nitrifying bacteria (Nitrosomonas and Nitrobacter) decrease exponentially with the depth of sediments (1). Nitrification reactions need oxygen,

but the processes can go on at dissolved oxygen (DO) concentrations as low as

0.3 mg 1 (10). Nitrification rate is described by the Michaelis-Menten

36

36-" """"
0..........

300-

00

* 0 Off~

0 0

0C

0

" M 200- 00 CD

080

0 0

3 0 000---

0 001

0 0 I

z0

V 00

a 100-

.0 0

01 0

0

0

0 0 Lake Kasumigaura

0-

0 5 10

NH4-N (mg Ii)-.-r

Figure 4. Relationship between NH 4-N concentration in

dissolved form and in adsorbed form in the

sediments in Lake Kasumigaura

equation as a function of NH 4-N and DO concentrations in the pore water. t

Nitrification also depends upon temperature. Nitrification rate in the it

* layer ki is:

T-30 NH DO

kNi kN3O N Ki + NHi 1

KDO +_______ DO, exp(-B-i) (6)

DO concentration in the sediment is:

___ OO)

at DO az2 kDO~z 7

37
In steady-state condition,

DO DOW. exp (-IkDo/DDo. z) (8)

DOW is DO concentration in the sediment-water interface and assumed to be

nearly equal to DO concentration in the overlying water.

Rate of DO consumption in the sediment is:

kDo k30 ."DO (9)

Therefore, from Equation 8 and Equation 9 DO concentration in the ith

layer DO. is: 3- --

DO =DOW.exp 30-TD 0 Do.i (10)

Denitrification in the sediment in Lake Kasumigaura can be described by

the Michaelis-Menten equation kinetics as a function of NO -N concentration in x the pore water (26). Nakajima (25) defined the function to express the in- hibition of denitrification by DO concentration in the sediment:

f(DOi) = I for DO. < 0.48

1/[I + 32(DO - 0.48)] for DO > 0.48 (11)

Denitrifiers are known to decrease exponentially with the depth of the

th sediment in Lake Kasumigaura (1). Denitrification rate in the i layer kL

is:

NO .. '- - ',

T-30 NO k k + *f(DOi)-exp(-yi) (12) Di D30 Ox i

Dissolved nitrogen compounds in the pore water are transported by diffusion. Also, the mechanism responsible for release of NH -N and NO -N in the 4 x

pore water from the sediment into the overlying water is diffusion across the

sediment-water interface. Many researchers have attempted to evaluate the

diffusion coefficient in sediment using various methods, but the estimated

-4 -7 2 -1

values range widely from 2 x 10 to 10 cm s (7, 22, 23). The nutrient

exchange across the sediment-water interface is a combination of physical,

chemical, and biological processes such as molecular diffusion, bioturbation,

physical mixing, and adsorption-desorption. These processes are complex and

difficult to measure separately. Accordingly, at present, it is difficult to

evaluate effective diffusion or transport coefficients incorporating the

above-mentioned processes. Freedman and Canale (7) applied the correlation of

diffusion coefficient with porosity shown by Manheim (23) to the sediment of

White Lake and evaluated flux from the sediment. Lerman (22) presented a

38-. -

.* - . . . . . . -. *.~* : . - .' 38-. . - . . . .. *". -. '"
relationship between diffusion coefficients and porosity using data from Manheim (23). The value of the diffusion coefficient Di is in proportion to

Di 2 2

D2 = D (13)

* where D0 is the value of the diffusion coefficient in the bulk (that is

f 1). Diffusion coefficients increase proportionally with temperature:

DTi Di (I + a.T) (14) .

MODEL FORMULATION AND PARAMETER EVALUATION

Table 2 shows state variables used in the model of nitrogen release from

bottom sediments. A list of forcing functions is shown in Table 3.

The differential equations and adjunct equations to define this model

containing sedimentation processes and nitrogen transformation processes are

shown in Table 4. The equations with associated descriptors are essentially

self-explanatory.

Field data from Lake Kasumigaura and laboratory data using sediments of

Lake Kasumigaura were used extensively to evaluate the parameters defined in

the model formulation. If sufficient information was not available, literatures were also consulted to provide a range of values for the parameter. 'il..':

Table 5 shows the values of parameters used in the model.

Ammonification rate gi is determined by decomposition experiments using

deposited materials and sediments taken from various depths of the sediment . . .

" (Hosomi, unpublished data). It is also estimated from the vertical distribu-

-.- tio% of BDN and the sedimentation rate.

Ukita (35) used 0.05 d as the first-order kinetic coefficient in the

sediment on decomposition of BDN. Otsuki and Hanya (31) obtained 0.02 d as the decomposition rate of dead algae at 20*C.

-4 -2 -1

The estimate values ranged widely from 10 to 10 d - . Accordingly,

ammonification rates were determined by the model calibration in this study in

the range of estimated values.

MODEL CALIBRATION

Concentrations of nitrogen compounds in the overlying water and the

sediment measured in January were averaged for 4 years (1981-1984) and used as

initial values of state variables in the model.

The results of model calibration using the 1980-1982 data as forcing

function are shown in Figure 5. Measured data of NH -N release flux during 4 1981-1984 were averaged each month and shown by mean values and standard

-2 -1 deviations. Maximum NH 4-N release flux (about 70 mgN m d- ) was observed

39

7'•.%

4A_.' .. #__ . a2 '__._ Y. V .".- f, _'" " '..'............... '.. .. _' f'_. . .... * f ' S..,.f .-. '_.". ....... '-.'.. ,.'". _. ".."....-,.*."2 _.\.'_2_-
,- v-~~wzi ~ w~ryA U ~ .W.--~, ~- ~ - - . -..- * .- .-.. .

TABLE 2. STATE VARIABLES USED IN THE MODEL OF NITROGEN RELEASE

FROM LAKE SEDIMENTS

Symbol Definition Unit

NHi NH 4-N concentration in the pore water of the gN m *

ith layer in the sediment

q Adsorbed NH -N onto the solid sediment phase gN g dry th sediment

of the i layer in the sediment

NO. NO -N concentration in the pore water of the gN m

i layer in the sediment

BDN Biodegradable nitrogen (BDN) in the solid gN g dry sediment of the ith layer in the sediment sediment .

SN Stable nitrogen (SN) in the solid sediment gN g dry

of the i layer in the sediment sediment

TABLE 3. FORCING FUNCTIONS USED IN THE MODEL OF NITROGEN RELEASE

FROM LAKE SEDIMENTS

Symbol Definition Unit

NHW NH -N concentration in the overlying water gN m-3

4

NOW NO -N concentration in the overlying water gN m-3

-3 "-

DOW Dissolved oxygen concentration in the overlying g m-3

water

PON Particulate organic nitrogen concentration gN m- 3

in the overlying water

T Water temperature OC

40

.. :.S.. -:
TAL .THE DIFFERENTIAL EQUATIONS AND ADJUNCT EQUATIONS TO DEFINE h

TABLE 4THE MODEL OF NITROGEN RELEASE FROM LAKE SEDIMENTS

1) NI-b-N concentration in the pore waeter of tise i-ti, layer in the sediment, NH, (gN M-3 )

odNHi fss.06NHW _NHi-qOiS, 4 NHi-A V1 _ DTr( i+00-H -NHWV)

'dt 4Z-(1-01 ) AZ 4zZ (A) 2

gain due to sedimentation advection diffusion across the

moving boundary by compaction sediment- water interface

+DT2-(,+ 2).(N112 -NHi)+p(1 )i- kv

diffusion across the 1st ammonification nitrification

Iayer-2nd layer interfaceW

for i 2

dNH - H,-0.,-S,-~ _ NH,-.2 -AK- _N W.. OeS, NH,-A . - NH. ZAZA + A

sedimentation advection by sedimentation advection by

compaction compaction

DT,.40, - ,) *(NH, - NH-i) DT. i-(qi+ 0.i)-(NH.. I- NW,

2 -WA) +2-(4Z)'

diffusion across the upper interface diffusion across the lower interface

ammonification nitrification

2) Adsorbed NH 4 -N onto the solid sediment phase of the i-th laver in the sediment.

q,. (gN g-1 dry sediment)

K -NH,

for i= I

dq0 -p(-0- 1) -q1 -S,

sedimentation to the 2nd layer

for i k 2

sedimentation from the sedimentation to

upper layer the lower layer

(Continued)

(Sheet I of 3)

41
" .iT 

*

M

I .TMZiijV M T S.. 1. - z

TABLE 4 (CONTINUED)

3) NOx-N concentration in the pore water of the i-th layer in the sediment, NO, (gN m_)

for i= 1+ __

dNO1 fssj-OtNOW NOctSi+ NOAV DTi(1+0j)(NOi-NOW)

-dt ,Z- 0 ,AZ + ,Z (,AZ) 2

gain due to sedimentation advection by diffusion across the

moving boundary compaction sediment-water interface _.

+.DT2"(#,+ '(NO2 '.~ -NO) + ¢IkNa - 'ko, 016 - '.o° 2 .(,dZ)2. ...

diffusion across the 1st nitrification denitrification

layer-2nd layer interface

for i&-2

0, dNO, NO,-r0-S,-_ NO,-1'AVi-_ NO, S So' + NO,'AV

dt I a z z z - -: ?

sedimentation advection by sedimentation advection by

compaction compaction D T, .( 0i-t +-i)'(NO, -NOi-,).,d) D T,. v( O,., + @,)'(NOv.. ( ) - NOd 

2 .(AZ)2 + 2.(AdZ)2

!ifs on across the upper interface diffusion across the lower interface

+ 0. -kkv - 4, iDo

nitrification denitrification

4) BDN (Biodegradable Nitrogen) in the solid sediment phase of the i-th la.er in the sedimnt.

BDN, (gN g-1 dry sediment)

for i=1

dBDN _ fss.PON-Oi.E BDN.S, V.P.V.E

dt A-- IZ ,)-p 1 - + Z(I-t)'p 00 1 

gain due to sedimentation to ammonification PON deposition

moving boundary the 2nd layer from the overlying water

for i a 2

dBDN, BDN,-,'S,-i'(I- 0-) BDN,'S,

dt tz.(-' ,) AZ - ' (I')

sedimeotation from the sedimentation to ammomfication

upper layer the lower layer

'- %° '

• .'-. .-

(Continued)

(Sheet 2 of 3)

42

.... ......-,-. ..... .A .... • | 
TABLE 4 (CONCLUDED)

5) SN (Stable Nitrogen) in the solid sediment phase of the i-th sediment layer, ..

SMj (gN g-I dry sediment)

for i = 1

dSN, _ ss-PON- 0, -iE) SNt -S, + Vv-PON(-E)

dt z1Z_(j-0j)2 _p 4Z Z0 0-

gain due to moving sedimentation to PON deposition

boundary the 2nd layer from the take w-ater.-

for i 92

sedimentation from the sedimentation to

upper layer the lower layer

6) Adjuinct equations

Sedimentation rate of the i-tb sediment layer. 5, (m d-')

Advection induced by compaction in the i-th layer. A V, (m d-')

A,= (.LI - I .~

Ammownificationa ini the i-ti, laver, g, (gN g-I dry sediment d-1)

gi= 930 -BDN, O 8T30, exp (-&-i)

Nitrification in the i-ti, Inr, k1, (gN m-' d-')

k =i k.v3o, 0

- 9T-30. NH, DO, x(-8i

K5vm4 +NH, Koo+DOi x -li

DO concentration in the i-tb layer. DO, (9 rn- 3)

DO, = DOW - exp (-!k oeo?

D',,itrification in the i-tb latwvr. kn, (gN m'~ d -')

KvxNO

ithere f (DO,) I for DO, < 0.48

I

1+32 -(DO, - 0.48) frD,~04

(Sheet 3 of 3)

43
TABLE 5. VALUES OF PARAMETERS USED IN THE MODEL OF NITROGEN RELEASE

FROM BOTTOM SEDIMENTS

ft .

Parameter Unit Values Found by

ft. ~3 -3 "f *j Porosity m m 0.90+(0.96- Measurements 0.90) exp ,-.*.

(-0.1171)

3-2 d-1 _

f Volumetric flux of m3 m d 0.0000010 Estimated value on

sedimentation from the basis of Otsubo

water to sediment et al. (30)

surface

2 -1 D Molecular diffusion m d 0.0000864 Lerman (22)

coefficient at O°C

2 -1 D Diffusion coefficient m d 0.0000475 Revsbech et DO of dissolved oxygen al. (34)

a Empirical constant 0.04 Lerman (22)

-3 p Density of solid g m 2400000 Measurements

g30 Ammonification rate d 0.02 Calibration in the

(BDN decomposition rate) range of estimated

in the top layer of the values on basis of

sediment at 30°C Hosomi and Sudo (12),

Otsuki and

Hanya (31), and

Ukita (35)

KNO5.0 Measurements

K Nitrification rate in gN m d

top layer of the sediment at 30*C

K 3 1100 Estimated value on D30 Denitrification rate in gN m- 3 d- 1 basis of Nakajima

the top layer of the and Aizaki (26)

sediment at 30*C

K -1 30 Estimated value on

DO consumption rate in d basis of Okada and

the top layer of the Sudo (29)

sediment at 30*C r" - 1.15 Measurements

9 Temperature coefficient

0N 1.07 Measurements

Temperature coefficient

D .08 Measurements

Temperature coefficient

(Continued)

44

. .1
TABLE 5. (CONCLUDED)

Parameter Unit Values Found by

0DO Temperature coefficient 1.08 Edberg and

* DO Hofsten (6)

a Empirical constant to 0.8 Calibration

express the vertical

distribution of

ammonifiers

Empirical constant to 0.4 Estimated value on

express the vertical basis of Aizaki

distribution of nitrify- and Nakajima (1)

ing bacteria

*Y Empirical constant to 0.4 Estimated value on

express the vertical basis of Aizaki

distribution of and Nakajima (1)

denitrifiers

-3 KNH4 Michaelis constant for gN m 0.1 Barnes and Bliss (4)

NH -N concentration 4 on nitrification

-3

- KN x Michaelis constant for gN m 0.5 Nakajima and

NO -N concentration Aizaki (26)

onXdenitrification

-3

K D Michaelis constant for g m 0.3 Barnes and Bliss (4)

DO concentration on

nitrification

3 -1

K Adsorption coefficient m g dry 0.00004 Measurements

sediment

VN Settling velocity of PON m d 0.08 Estimated value on in the overlying water basis of Fukushima, .'.-

Aizaki, and

Muraoka (8) and

Goda (9)

E BDN fraction of PON in 0.8 Estimated value on

the overlying water basis of Otsuki and

Hanya (31)

45

% Z
00 Observed Data

Mean 1 Standard Deviation

z

J F MA M J JASO N D ., ,

Figure 5. NH 4-N release flux from bottom sediments in Lake

Kasumigaura; comparison of model calculations and

observed data

during the summer and early autumn. The measured flux decreased with the

decrease in water temperature, and, in most cases, was no more than

-2 -1

10 mgN m d during winter and early spring. Good agreement between the

model calculations and measured release flux of NHd-N was noted. The calculated seasonal change in NH 4-N concentrations in the pore water of the upper

layers (0-6 cm) agreed fairly well with the observed profiles of NH -N concen4

trations (Figure 6), whereas the calculated NH4-N concentrations in lower

layers (6-20 cm) were lower than those of the observed data during the summer

and early autumn. It must be noted that the increase in values of NH 4-N

concentrations in lower layers (6-20 cm) during summer and early autumn had

little effect on NH -N release flux. This result suggests that the nitrogen 4

dynamics of the upper layers of the sediment regulates the nitrogen transportation between the sediment and the water.

Figure 7 shows comparisons of model calculations (PON - BDN + SN) and

observed PON in the surface sediment. The calculated PON in the 1st layer

increased since autumn, while the calculated PON in the 2nd layer and the 3rd

layer decreased. Observed PON in the surface sediments was approximately constant within the range of sampling and analytical errors. These results

seemed to be caused by the fact that this model did not consider mixing of

sediment particles due to biological and physical action, e.g. organism burrowing and waves, because sufficient quantitative data were not available to

evaluate the mixing rates of sediment particles in Lake Kasumigaura.

46

.................... ... ... - . ...-.. .. . -a . ** .%. -

*. . .. .. . . . . . . . . . . . . . .
Observed Data In the 0-lam layer

- IMeant I Standard Deviation

E

Cacula ted

fb:re Data ith -anlayer

Mea ± 1 S tandard Deviation

z

E 5-4

z

5 Calculated(3-4cm layer)

10- __ _ _ _ _ _ _ _ _ _ _ _

fObserved Data

In the 4-6cm layer

Meant I Standard Deviation z1

Calculated !5 (S-cmn ayr

z (-Scmn layer)

J F MA M J J A SO0 NO0

Figure 6. NH -N concentration in the pore water

in 4the surface sediment of Lake

Kasumigaura; comparison of model

calculations and observed data

47 .

5- .. * **. .'. .- *,%
"'-" ~Calculated -'

0 J- Calculated.,

" :~~ %2-cm la yerd -

Observed Data'.

5- Calculated...

* O-3crm layer (1978) (1-2cm layer) ;'

E -. o o-2cm layer (1980) ?' :

_ ~0-2¢m layer (1981) _-.-

z o o-,©m layer (1983), .

N 0 -2cm layer (19414) ....

.L 0 --- : :

| F M A M J J A S 0N D

Figure 7. PON in solid sediment in Lake Kasumigaura;.',-

comparison of model calculations and.-.-

observed data ..

Therefore, further studies on mixing effects of sediment particles is neces- -. sary. However, because observed data of PON are mean values in the 0-3 cm or

0-2 cm layers of the sediment, the average values of calculations for 0- cm, -2 cm, and 2-3 cm laye 0 lar (1984)agreement with the observed values.

Figure 8 shows comparisons of calculated and observed values of NO -N

x . release flux and NO -N concentration in the interstitial water of the Ist

", X layer. Contrary to NH4N flux, NO -N flux was observed from overlying water

xr

to the sediment almost all the year. The agreement between the model calcuaylatHons and the observed data was good, but some data deviated from the model

2calculations.

In order to gain additional insight into the nitrogen dynamics in the

sediment-water system, characteristics of the model were examined Long-term

(10 years) calculation was carried out using the same forcing functions to .,:' affirm the stability of the model. As shown in Figure 9, seasonal variation

of NHC4-N release flux was the same since the 2nd year. This result originates

from the fact that BDN in the upper layer regulates the ntrogen transportution between the sediment and water and most BDN is originated from PON in the

overlying water after 2 years.

Annual average flows of nitrogen in the upper layers of the sediment after the 0th year (probably steady-state) are shown in Figure . It should

be noted that NH N release flux is equivalent to 87 percent of PON

44

; ~48 ° '

* ~ from ~ th .D fac tha in th upe lae reuae th.irgnrnpra
10

/observed Data !

z 5 - D .,,,ao n

0.3%

L

"* " " -Calcul ted """

" -10.

J F M A M J J A S O N D

0.3-N Observed Data in the 0-1cm foyer

Moan! 1 Standard Deviation

Z 0.2-

E

z, 0. 1 .. ,.a1CUat~

~..-Ca..u.ate

J F M A M J1 JA SO0N D

Figure 8. NO -N release flux from bottom sediments (a) and

NO -N concentration in the pore water in the top

layer of the sediment (b) in Lake Kasumigaura;

comparison of model calculations and observed data .e:

sedimentation flux from the overlying water to the sediment. The rate of

ammonification, nitrification, and denitrification in the 1st layer of the

sediment played an important role on the nitrogen transformation in the total

sediment system. N release flux depended on ammonification of BDN. The

flux from the 2nd layer to the 1st layer was not negligible, but this flux

also depended on the ammonification of BDN in the 2nd layer.

SENSITIVITY ANALYSIS

A sensitivity analysis of the model parameters for annual mean NH -N 4

4release flux was carried out to provide further insight into the mechanism of,...

nitrogen release from the sediment and to identify further research needs.

By doubling or halving the parameter values of the control simulation

obtained by the calibration mentioned above, the ratios of the annual mean

N Nrelease fluxes estimated both from perturbed and control simulations

were determined (Table 6). Short-term and long-term effects of parameter sensitivity on annual mean NH4-N release flux were estimated by the simulation of

the 1st year and the 10th year, respectively.

49
.~.tooIE

50

0

1 2 3 4 5 6 7 8 9 10

YE A RS

Figure 9. Simulation of NH -N release flux from bottom sediments 4 in Lake Kasumigaura.

WATER 36.7 32.0 2.0

SEDIMENT21

BDN NI-4 3.

15.4 :: 13.4 0.3:s layer

6.9 ~ ____NX. .>.

B DN ZE .N H4 0~

5o{6 2.5 2nd layer .-

B D N =~N H4 0 NXo

01 3rd layer

1.0 0

5.0: 3.0 I 4th layer

p 0.5

BDN - NH4- -NOx--

5th layer

Figurc. 10. A ,nual average flows of nitrogen in the upper layers of

the sediment in the 10th year

50
TABLE 6. SENSITIVITY OF ANNUAL MEAN NH -N RELEASE FLUX FROM BOTTOM

4 .

SEDIMENT RESPONSE TO PARAMETER VALUES (THE RATIOS OF

ANNUAL NH 4-N RELEASE FLUXES ESTIMATED BOTH FROM PERTURBED .'.

AND CONTROL SIMULATIONS.)

Ratio of perturbed/control simulation

Short term (1st year) Long term (10th year)

Parameter x 1/2* x 2** x 1/2* x 2**

VN 0.79 1.42 0.52 1.96

930 0.66 1.42 0.80 1.10

a 1.27 0.82 1.12 0.84

kN30 1.05 0.91 1.05 0.92

k 1.00 1.00 1.00 1.00 * D30

K 1.01 0.98 1.01 0.99

D 0.84 1.23 0.93 1.13

f 1.08 0.87 1.13 0.77

ss

* Halving parameter values of the control simulation.

•* Doubling parameter values of the control simulation.

Ammonification rate, g30 was the most sensitive parameter for NH4-N

release flux in the short term. But in the long term, settling velocity of

PON in the overlying water, VN , was more sensitive than g3 0 . The model

was also sensitive to the parameter a to define the vertical distribution of

ammonification rate. Therefore, further studies on the vertical distribution

of ammonification rate in the sediment and PON sedimentation flux from the

overlying water to the sediments would be necessary.

The results also show that increasing or decreasing the diffusion coefficient D does not change the annual mean NH4 -N release flux more signifi- 04

cantly than V N and g30 "

EUTROPHICATION CONTROL PROGRAMS

The effectiveness of eutrophication control programs on the nitrogen release flux rate from sediment was evaluated using the calibrated model. Sediment dredging, bottom sealing, artificial aeration, and reduction of external

loading as eutrophication control programs were studied.

51

-. • :':::
The same rates of ammonification, nitrification, and denitrification in

the top layer in the sediment were used in the eutrophication control simulations and control simulation based on the following.

a. The number of bacteria attached on the deposited materials is several

times as large as the bacteria in the surface sediment (0-2 cm

layer) (1).

b. BDN in the top layer is formed by BDN originating from the overlying

water except for the first year.

Accordingly, even if the sediment-water interface would be changed significantly as a result of sediment dredging or bottom sealing, bacterial

activity and BDN in the top layer in the sediment are not different from those

of the control simulation. However, ammonification, nitrification, and denitrification rates in the layers lower than the 2nd layer were assumed to be

zero in sediment dredging and bottom sealing simulations.

Initial conditions in sediment dredging and bottom sealing simulations

are shown in Figure 11. In the bottom sealing simulation, initial values in

the layer (0-10 cm) covered with nitrogen free fly ash and sand were all zero.

sediment-water interface

in the bottom sealing -10 - -"

simulation

water

sediment-water Interface 0

in the control simulation

E

sediment

BDN

o BON /4 NH4-

sediment-water Interface .

in the sediment dredging 10

simulation

Figure 11. Schematic diagram on the initial. conditions

of the control, sediment dredging, and

bottom sealing simulations

52

..- * ..- * -.. *& ... -.- . . . - A f ~ I fl .k. . ~ *fl .. * .* .~'.. ft.~. - . . .......
Artificial aeration not only increases DO concentration in the overlying PJ

water, but also stimulates nitrification activity in the sediment-water interface. In this simulation, the nitrification rate in the top layer at 30*C,

k 30 , was multiplied four times.

Reduction of external nitrogen loading would reduce the rate of deposition from the overlying water to the sediment. In this simulation, deposition

rate VN was halved irrespectively of the amount of external loading reduction. Figures 12-15 show the comparison of control simulation and the results

of eutrophication control programs.

In the case of sediment dredging, a large flux of NH4 -N from sediment was

observed immediately after the sediment dredging. This flux was caused by the

transfer of the highly accumulated NH4 -N in the pore water and adsorbed onto

the sediment particle in the lower layer to the surface sediment as a result

of dredging. Sediment dredging contributed only slightly to the reduction of

d4-N release flux with the exception of the summer season.

Sediment sealing seems to be a more effective countermeasure for NH -N

4

release flux than dredging. This result showed that highly accumulated dissolved and adsorbed NH -N in the surface layer of the sediment affected the

NH -N release flux. 4

Figure 14 shows that artificial aeration is an effective rehabilitation

technique for preventing NH4 -N release from the bottom sediment. Experiments

have confirmed that nitrogen did not release from the sediment to the overlying water under aerobic conditions except for a few days after initiation of

the experiments. NO -N may be the limiting factor in the denitrification in x

the sediment-water system because a large amount of organic matter was contained in the sediment. Aeration accelerated nitrification in the sedimentwater system and, as a result, denitrification occurred in the surface

sediment.

The 50-percent reduction of nitrogen deposition rate to the sediments was

most effective for the control of NH -N release from the sediment among four

cases studied. '4 L

CONCLUSIONS

A multi-component dynamic model for nitrogen in the bottom sediment-water

system of Lake Kasumigaura, a highly eutrophic and shallow lake, was developed. Nitrogen transformation and transportation processes were incorporated

into the model. In order to obtain quantitative information on the sedimentwater interactions and to identify the deficiency of our knowledge at present

and to determine future research needs, the model was calibrated and the sensitivity analysis of the model parameters was conducted.

Good agreement between the model calculations and obqerved data of NH -N

release flux from sediment, and NH -N and NO -N concentrations in the pore

water of the upper layer was noted.

53

. . . . . . . . • 
IN

%%

contro vSediment Dredging

-0 Control .- 

2 3 4 5 6 7 8 9 to

Figure 13. Effects of bottmn deling on NH 4-N release flux;

control vs. bottmn seling:

" !A

C 88 it •54

5 I" 8 ' , 8 ' 8

50 8 I !815 

" 8 8 8

"- 8 8

088 88

0"I - 2 3 4 5 6 7 8 9 IO,-.10. . :. 

Figure 12. Effects of sedmt deding on NH4 -N release flux; '--..

control vs. sedmt deding

-Botom-Sealn Lake 

SCon•troL ,. -.

"- ----- - .---..--.-. 2 :""-"' --- """v "".v :.v - . ' ." . . . ...- , . -.-.- -, . . ,., -. ) 8':'k 'i :
Artificial Aeration

-------- -------------------------------- Control

~50 ( s/55 11

0

2~ 3 4 5 6 7 8 I

coto vs ariica aeratio

~Reuto of Exera LoadingI 

50

1 2 3 4 5 6 7 8 9 t0

Figure 4. Effects of artificial aerationn ofxna -nirles flux;n o

Nrls. o artifciatrl aeration n rdutonofORloadingLodin Reduction ofroe 

* ii I 555

* LA7
Annual average flows of nitrogen in the upper layers of the sediment

showed that the rates of ammonification, nitrification, and denitrification in

the 1st layer of the sediment played an important role on the nitrogen dynamics in the total sediment system. Further studies on the vertical distribution of ammonification rate were found to be necessary from the sensitivity

analysis.

The effectiveness of eutrophication control programs on the nitrogen

release flux from sediment was evaluated using the calibrated model. The

reduction of nitrogen deposition rate to the sediment and the bottom sealing

were more effective than the sediment dredging for the control of NH -N

release from the sediment. r- .

REFERENCES

1. Aizaki, M., and Nakajima, T. 1981. "Characteristics of Bacterial Distribution Related to Nutrient Dynamics in Lake Kasumigaura," Res. Rep.

Natl. Inst. Environ. Study., Jpn., No. 22, pp 63-87.

* 2. Aizaki, M., et al. 1984. "Limnological Data in Lake Kasumigaura," Res.

Data Natl. Inst. Environ. Study., Jpn., No. 25, pp 1-149.

* 3. Andersen, J. M. 1974. "Nitrogen and Phosphorus Budgets and the Role of

Sediments in Six Shallow Danish Lakes," Archiv fur Hydrobiologie, Vol 74,

pp 528-550.

4. Barnes, D., and Bliss, P. J. 1983. "Biological Control of Nitrogen in

Wastewater Treatment," E. & F. N. Spon, 146 p.

5. Chen, C. W., and Orlob, G. T. 1975. "Ecological Simulation for Aquatic

Environments," Systems Analysis and Simulation in Ecology, B. C. Patten,

ed., Vol 3, Academic Press, New York, pp 475-588.

6. Edberg, N., and Hofsten, B. V. 1973. "Oxygen Uptake of Bottom Sediments

Studied In Situ and in the Laboratory," Water Research, Vol 7,

pp 1285-1294.

* 7. Freedman, P. L., and Canale, R. P. 1977. "Nutrient Release from Anaero- -

bic Sediments," Journal of the Environmental Engineering Division, ASCE,

Vol 103, No. EE2, pp 233-244.

8. Fukushima, T., Aizaki, M., and Muraoka, K. 1984. "Characteristics of

Deposited Matter at Takahamairi Bay in Lake Kasumigaura," Res. Rep. Natl.

Inst. Environ. Stud., Jpn., No. 51, pp 89-101.

9. Goda, T. 1984. "Summary of Researches, Comprehensive Studies on the

Eutrophication Control of Fresh Waters (VIII)," Res. Rep. Natl. Inst.

Environ. Stud., Jpn., No. 57, pp 53-94.

10. Hakanson, L., and Jansson, M. 1983. Principles of Lake Sedimentology, '.-

Springer-Verlag, Berlin, Heidelberg, New York, Tokyo, 316 p.

56

. . . * *o
11. Hosomi, M., and Sudo, R. 1979. "Studies on the Effects of Sediments on

Alga. Growth-Algal Growth Potential of Sediments," Research Report from

the National Institute for Environmental Studies, No. 6, pp 115-121.

12. Hosomi, M., and Sudo, R. 1984. "Release of Nitrogen and Phosphorus from

Sediments of Lake Kasumigaura," Res. Rep. Natl. Inst. Environ. Stud.,

Jpn., No. 51, pp 191-217.

13. Hosomi, M., Okada, M., and Sudo, R. 1979. "Effects of Bottom Sediments

on Algal Growth. -- NH4 - Release from Lake Sediment," Conference of the

Society of Fermentation Technology, Japan, pp 215-216.

14. Hosomi, M., Okada, M., and Sudo, R. 1981. "Release of Phosphorus from

Sediments," Verh. Internat. Verein. Limnol., Vol 21, pp 628-633.

15. Hosomi, M., Okada, M., and Sudo, R. 1984. "A Comparison of Methods for

Estimating Nutrient Release from Lake Sediments," Management of Bottom

Sediments Containing Toxic Substances, published by US Army Engineer

Waterways Experiment Station, Vicksburg, Miss., pp 238-258.

16. Jorgensen, S. E. 1976. "A Eutrophication Model for a Lake," Ecological

Modeling, Vol 2, pp 147-165.

17. Jorgensen, S. E., Kamp-Nielsen, L., and Jacobsen, 0. S. 1975. "A Submodel for Anaerobic Mud-Water Exchange of Phosphate," Ecological Modeling, Vol 1, pp 133-146.

18. Kamiyama, K. 1979. "Studies on the Release of Ammonium Nitrogen from

the Bottom Sediments in Freshwater Regions, VI, A Model for Ammonium

Nitrogen Movement in the Surface Layer of Sediments," Jpn. J. Limnol.,

Vol 39, pp 181-188.

19. Kamiyama, K., Okuda, S., and Kawai, A. 1978. "Studies on the Release of

Ammonium Nitrogen from the Bottom Sediments in Freshwater Regions, III,

Ammonium Nitrogen in the Sediments of Different Water Regions," Jpn. J.

Limnol., Vol 39, pp 171-175.

20. Kamiyama, K., Okuda, S., and Kawai, A. 1979. "Studies on the Release of

Ammonium Nitrogen from the Bottom Sediments in Freshwater Regions, V,

Seasonal Variation of Ammonium Nitrogen in the Sediments in the South

Basin of Lake Biwa," Jpn. J. Limnol., Vol 40, pp 169-175.

21. Larsen, D. P., et al. 1979. "The Effect of Wastewater Phosphorus Removal on Shagawa Lake, Minnesota-Phosphorus Supplies, Lake Phosphorus and

Chlorophyll a," Water Research, Vol 13, pp 1259-1272.

22. Lerman, L. 1978. Geochemical Processes Water and Sediment Environments,

John Wiley and Sons, 481 p.

23. Manheim, F. T. 1970. "The Diffusion Ions in Unconsolidated Sediments,"

Earth Planet. Sci. Lett., Vol 9, pp 307-309.

.".

. 57 " 4J"

raft'*

*. *l * * *.**%* * * * * * *

.' '-.' .- -.- '-.' . . .' -~ '. ,'°' .'-i .'-.' .i m-i -, h".-i m,•.-, ,' ' ' " ".- -.-. .1.m "," -"- .ma" ,",-"i • " .lm ,",'" "- .'-'.'-'J-','.'.~bi iibIiiI ma
24. Morse, J. W. 1974. "Calculation of Diffusive Fluxes Across the

Sediment-Water Interface," Journal of Geophysical Research, Vol 79,

pp 5045-5048.

25. Nakajima, M. 1983. "Nutrients Cycle in Eutrophic Waters - Processes on

Sediments and Gas Exchange," Ph.D. Thesis, University of Tokyo.

26. Nakajima, T., and Aizaki, M. 1981. "Denitrification in Sediments of

%N Takahamairi Bay, Lake Kasumigaura," Res. Rep. Natl. Inst. Environ. Stud.,

No. 22, pp 89-97.

27. Nyholm, N. 1978. "A Simulation Model for Phytoplankton Growth and

~~~Vol Nutrient 4, pp Cycling 279-310. in Eutrophic, Shallow Lakes," Ecological Modeling, [ )

28. Okada, M., and Sudo, R. 1978. "The Effects of Sediment on Lake Eutrophication: The Application of Algal Assay Procedure," 4th U. S./Japan

Experts Meeting on Management of Bottom Sediments Containing Toxic Sub- , ...

stances, EPA-600/3-78-084, Environmental Protection Agency, Corvallis,

29. Okada, M., and Sudo, R. 1981. "Dissolved Oxygen Consumption in Lake

Sediments," Management of Bottom Sediments Containing Toxic Substances,

published by US Army Engineer Waterways Experiment Station, Vicksburg,

Miss., pp 106-120.

30. Otsubo, K., et al. 1984. "Characteristics of Physical Properties and

Nutrients Distributions of Mud in Lake Kasumigaura (1) Distributions of

Physical Properties," Res. Rep. Natl. Inst. Environ. Stud., Jpn., No. 51,

pp 157-173.

31. Otsuki, A., and Hanya, T. 1972. "Production of Dissolved Organic Matter

from Dead Green Algal Cells, I, Aerobic Microbial Decomposition," Limnology and Oceanography, Vol 17, pp 248-257.

32. Otsuki, A., Kasuga, S., and Kawai, T. 1981. "Seasonal Changes of the

Total Phosphorus Standing Crop in a Highly Eutrophic Lake: The Importance of Internal Loading for Shallow Lake Restoration," Verh. Int.

Verein. Limnol., Vol 21, pp 634-639.

33. Otsuki, A., Kawai, T., and Aizaki, M. 1981. "Dynamics of Phosphorus and

Dissolved Inorganic Nitrogen in Highly Eutrophic Lake Water of

Takahamairi Bay, Lake Kasumigaura," Res. Rep. Natl. Inst. Environ. Stud.,

No. 22, pp 3-21.

34. Park, R. A., et al. 1973. "A General Model for Simulating Lake Ecosystem," Simulation in Review, pp 30-50.

35. Revsbech, N. P., et al. 1980. "Distribution of Oxygen in Marine Sediments Measured with Microelectrodes," Limnology and Oceanography, Vol 25, .

pp 403-411.

58"...

7 ,'-~~~~~..-.-..-....-. -.--.........-..... ..--.-.---........ '. . '"" .... ""... .... "...."-->-5 --- , • " . "C- - -' " - y- . . . . . . -' .. .. . ¢,.. . .. _,. . ".. '. -. . -,
F " ' - -*b." *i%-- " '-'-- - 'L -'L--% ' I - - - * " 

:. - - a. - - - *

36. Ukita, M. 1982. "Study on Mechanism of Eutrophication and Ecological

Aspects of Nitrogen and Phosphorus Sources in Japan," Ph.D. Thesis, University of Kyoto.

37. Vanderborght, J. P., Wollast, R., and Billen, G. 1977. "Kinetic Models

of Diagenesis in Disturbed Sediments, Part 2, Nitrogen Diagenesis," Limnology and Oceanography, Vol 22, pp 794-803.

38. Welch, E. B. 1977. "Nutrient Diversion-Resulting Lake Trophic State and

Phosphorus Dynamics," EPA-600/3-77-003, Environmental Protection Agency,

Corvallis, Oreg.

."-or .'.. .~..-."

°.4,

. . . . . . . . . . .. . . . . . .*.... 

" " .22.2

.. 1~. -i
NOTATION

a Empirical constant

AV Advection velocity induced by compaction in the i th laer dlayer

BDN Biodegradable nitrogen in the solid sediment phase of the i t layer,

gN g dry sediment

D Molecular diffusion coefficient of NH -N and NO -N at 00 C and in the

0 44- 

bulk, m d

DD Molecular diffusion coefficient of dissolved oxygen at 0*C and in

the bulk, mn2 dI

D Diffusion coefficient of NH -N and NO -N in the i th lyrin the

porosity V m nd 1 

ae

t -3

DO Dissolved oxygen concentration in the i layer, g mn

i"i

DOW Dissolved oxygen concentration in the overlying water, g miDT Diffusion coefficient of NH -N and NO -N in the at TC, -layer 

1 2 -1 4 x m d

E BDN fraction of PON in the overlying water

* f(DOi Function to express inhibition of denitrification by DO cancentra- -

tion in the i layer

Bf Volumetric flux of sedimentation from the overlying water onto the

sediment surface, m m d

S Rate of BDN decomposition at 30C in the surface sediment, d

the ulkm 2 d I "'Z".

D1 Rate of ammonification in the i layer, gN g dry sediment d

3. -,--

K Adsorption coefficient, ion g -1 dry sediment

k Rate of DO consumption at 30NC, d

30 -

E B fRate of denitrification at 30C in the surface sediment, gN m d

th - 3 -1

kd, Rate of denitrification in the i layer, gN m d

-3.

SDO Michaelis constant for DO concentration on nitrification, g m

-3 -1 k Rate of nitrification at 30% in the surface sediment, gN m d

N30

-3 I"""

kH4 Michaelis constant for NH -N concentration on nitrification, gN m -3

60

.......................................... *.,,-. .... ....
-' - ' ~ - 7 - - .o.,

jth -3 -1 k i Rate of nitrification in the i layer, gN m- d

%Ox Michaelis constant for NO concentration of denitrification, gN m-3 x 1

NHi NH4-N concentration in the pore water of the ith layer, gN m 3

1 -3

NHW NH -N concentration in the overlying water, gN m- 3

4

NOi NO (-NO2+NO3-N) in the pore water of the ith layer, gN m 3

x

PON Particulate organic nitrogen concentration in the overlying water,

gN m- "'"

q Adsorbed NH -N onto the solid sediment phase in the ith layer, -1 4

gN g-I dry sediment ...

Si Sedimentation rate of the i layer in the sediment. This velocity

term is caused by the combined effects of sediment accumulation and -

compaction, m d- I

th - SNi Stable nitrogen in the solid sediment phase of the i layer, gN g

dry sediment

SW Net velocity of pore water, m d

T Water temperature, 0C

VN Rate of PON deposition from the overlying water, m d- 1

Az Thickness of the sediment layer, m

a Empirical constant to express the vertical distribution of

ammonifiers

Empirical constant to express the vertical distribution of

nitrifying bacteria

Y Empirical constant to express the vertical distribution of

denitrifiers

8 Temperature coefficient

g

N Temperature coefficient

D Temperature coefficient

D

DO Temperature coefficient

Porosity of sediment in the i h layer, i.e. volume fraction of pore

3 -3 water per unit volume of bulk sediment, m m"

61
* Ultimate porosity, i.e. porosity decreases with the depth by the

sediment compaction and levels off at the specific depth, m3 m 3

p Density of solid sediment phase, g m -3

6,.

p•. *°,_.

......... ,.--
STUDY ON CHEMICAL BEHAVIOR BETWEEN SEDIMENT AND UPPER WATER, "

H. Nakanishi, Professor

M. Ukita, Assistant Professor

Y. Kawai

Division of Sanitary Engineering Department of Civil Engineering, Yamaguchi University 4L*,:

Tokiwadai 2557, Ube-city, Yamaguchi Prefecture, Japan 755

ABSTRACT

This study investigated modeling for the

assessment of eutrophic water and sediment quality,

with a focus on the exchange of nutrients between

water and sediments and on the primary production of

phytoplankton.

This model was applied to a simplified core system consisting of two layers of water and two layers

of sediment. The fundamental elements were phosphorus, nitrogen, oxygen, and iron. Sulfide ions were

regarded as debts of dissolved oxygen (DO), and ferric

oxide as a source of DO, respectively. The oxidized

zone (ferric oxide), which has a certain capacity of

phosphate adsorption, is formed by the reaction of

active iron in the upper layer of sediment with DO in

the lower layer of water. The oxidized zone is reduced by the sulfide ions in the upper layer of sediments and, thus, an equal part of the phosphate is

released. . I.,

The supply of phosphorus and nitrogen to the

sediment depends upon the settling of phytoplankton

from water. The phytoplankton decompose and are

partially adsorbed to the clay surface or to the

oxidized zone.

The released nutrients diffuse upward toward the

water or downward toward the lower layer of sediments.

The nutrients which diffuse upward are assimilated by

phytoplankton which settle onto sediments and recycle

in the same manner.

The main parameters were changed seasonally as a

function of temperature.

Using this model, the characteristic patterns of

seasonal variation of phosphate discharge from sediments, the DO concentration in water, and the rise and

fall of the oxidized zone were satisfactorily

simulated.

63

%
The method proposed here would be useful as a

significant submodel for prevailing water quality

assessments.

INTRODUCTION

In the recent past various efforts have been made in eutrophic water

areas to restore water quality: for example, by reducing the pollutant load

or by dredging polluted bottom sediment. With the rapid progress of computer

technology, many eutrophication models have been developed (2,6,7,10,12).

In order to evaluate the effect of these efforts on water quality, the

prediction of sediment quality is essentially needed. However, in most cases

of water quality assessment, the influence of sediment against overlying water

is generally expressed by constant terms. The complicated mechanism of phosphate release from sediment especially has not been satisfactorily

simulated (1,3,8,9,11,15). ,

This study, based on experiments and field surveys in eutrophic coastal £

sea areas, investigated the numerical model of the behavior of nutrients between water and bottom sediment.

WATER AND SEDIMENT QUALITY SURVEY FOR THE MODELING

Methods

Release Rate of Nitrogen (N) and

Phosphorus (P) from Sediments

By using the specially made core sampler, undisturbed sediment samples

10-20 cm deep were collected in acryl pipes 10 cm in diameter (Figure 1).

The experimental procedures of N and P release rate are indicated in

Figure 2. These experiments were made at a constant temperature and DO concentration similar to field condition. The release rate of N and P was calculated by measuring the increase of ammonium-N and orthophosphate in overlying

water for 3-5 days.

Determination of Soluble Nitrogen (SN),

Soluble Phosphate (SP), Biodegradable

Nitrogen (BDN), and Estimation of

Decomposition Rate Coefficient of

Organic Matter in Sediment (KD3)

SN and SP were determined as follows: ca. 5 g of wet sediment samples

were weighed into wide-mouth incubation bottles, filled with deoxygenated seawater and tightly closed, and then mixed vigorously. After 30 min, the super- "'-

natant was filtered with GFC filter paper and analyzed for ammonium-N and

ortho-P.

64

." '" ""°.-°°• - "-" \.- o,.*.*."' * ° . .* '' ... " • ' ,"- '.* - . " ..- '° .... * .." °.." .• .•• . °°. o . ° . '°" ° ,,"°k•* . -9
aluminium

pipe %YV,.

pol y- -

ethylene

funnel

connecting ,..

Figure 1. Core sampler ---. screwrubber

plug

acryl

pipe

(1OcmO)

BDN was determined by measuring SN after long-term incubation in filled

and tightly closed bottles. The decomposition rate coefficient K of organic

matter in sediment was estimated by the following first-order reaction

equation:

K = (1/t)ln[(Sd - So)/(Sd - St)] (1)

where

K = decomposition rate coefficient, day -

t = incubation period, days

Sd - ultimate BDN at 350 C for 30 days, pg/g wet sediment

So = initial Sn, pg/g wet sediment

St = SN after t days with the same temperature as field condition, pg/g

wet sediment

'-

.. . . . . . . . .. . . . . . . . . . . . . . . . . . . . .
. -. .... .-. ."... .

% 

.

!N

I'

Soon after field sampling, most of the overlying water is"-:

abandoned. Then seawater is added gently. The core is

submerged to the water bath of field temperature. After - ''

2 or 3 hr, a fixed volume of sample is taken for mea-..

surement of ammonium-N and ortho-P along a specified

time series. ,..

Figure 2. Experiment procedures for N and P release rate - -.-

from bottom sediments "" :;

Maximum Specific Production ! .-

Rate Coefficient in the Upper Layer of Water (KPI) mtfhori we s

In order to obtain the value of KPI, production and respiration rate and

the ratio of chlorophyll-a/Pss*, etc., were measured in the western part of

Seto Inland Sea in 1979 by using the pseudo-in-situ DO method. The incubationi ""{!'- 

period was 24 hr for both production and respiration. The former was

expressed as gross production rate.

Cultivation of Phytoplankton by

Microcosm Using Core Sample of Polluted Bottom Sediment

Using the apparatus indicated in Figure 3, various samples of phytoplankton were obtained. These were filtered with the GFC filter paper and

analyzed for CODcr (Standard Method), CODmn (JIS K0102), TKN, and TP.

hPss particulate phosphorus. This rate is used when we convert the resperation or production rate per unit amount of chlorophyll-a into per unit

amount of particulate phosphorous, i.e. phytoplankton. By converting the

value of t resprated or produced into phosphorous, then we can calculate

the values of KP or KDi.

powwi

anlzd o O.r(tndr eto) C n(IoK12) K, n P

* * ss prticlatephoshoru. Ths rae isusedwhenwe cnver•theres

* piration or-"". production rate per unit amount '" •°'-"- of '- chlorophyll-a- •. *. " . into .. per unit ,.•
culture

ii hi water-supply

Figure 3. Apparatus of micro- bottle

cosm for cultivation

of phytoplankton

.eserv-.ng I

water flask mud core

Results

*.', Seasonal Variation of N

and P Release Rate (RN, RP)*

The characteristic patterns of seasonal variation of RN and RP are presented in Figure 4. Both RN and RP have notable variations, but RP changes

. more markedly. The peak position of RN is shifting toward late summer.

Table 1 indicates the values of RN, RP, and RO measured in a similar manner.

"" Season Changes of the Vertical

Distribution of SN and SP in Sediment

. Figure 5 indicates the summer and winter pattern of vertical distribution

of SN and SP in the sediment of some fishery harbors. It shows that SN and SP

concentrations in surface layers rise in summer due to active degradation of

*: organic matter; thereafter they diffuse upward or downward according to the

concentration gradient.

Season Variation of Degradable

"* Organic Nitrogen (FN), Decomposition Rate Coefficient (KD3),

and DO Concentration of Water

Figure 6 shows the seasonal variation of FN and KD3 in the upper and

.. lower layers of Maruo Harbor sediment. It is noted that (a) KD3 has a value

ranging from 0.005 to 0.112 (day and higher in summer than in winter,

(b) M FN has a value ranging from 37 to 126 (pg/g wet sediment) and higher in

winter than in summer, and (c) both KD3 and FN have larger values and a more

remarkable variation in the upper layer than in the lower layer.

* RN, RP = released nitrogen and phosphorus from sediment to the overlying

water, respectively.

67

" ~. . . . . . . . . ... . o .. . . . . . . . -... - . .- - - -. -. .° . o--..... -'"+'.

v '-,.,'''',..""'', -':,..'-+-'-.....:." . . . ,... ; . . ,. .,,,,. -"., .-.-,.. ......-.,.... ,".".,.-"-',... . . .-.- , .'v -" . ,"," . v .-
5"

r0

Ai Maruo Harbor Mud Ube Off Mud

rpI -..rp(1978-'79) rp r0 rN '. .- rp

20 50010 0- . 20 ~100I~IC =. . "

-1 10 250 50. 1 10

~c.. C -0

_ -S0 0 4 6 10 12

2 4 6 8 10 12 (Moti th~

Figure 4. Seasonal variation of N and P release rate from sediments

TABLE 1. VALUES OF N AND P RELEASE RATE AND DO CONSUMING

RATE (RN, RP, RO) (g/m 2/day)

Sea Area Sampling Time n RN RP RO

Ube Off 4 times '77-'78 7 85 6.9 510

Tokuyama Bay Aug. Nov. '77 3 38 4.0 470

Fishery Ports Summer '75 7 194 36

near Ube Autumn- 7 86 10

Winter '77 7 75 7.4

West Suo Nada Aug. '79 40 23 3.3 310

Mar. '80 34 8 tr 170

Yamaguchi Bay Aug. '81 6 34 3.8 640

Mar. '81 3 4 tr 220

Tokyo Bay Sep. '76* 11 150 24 1800

Osaka Bay Aug. '76* 5 38 23 800

Hakata Bay Aug. '81** 27 76 5.0

Mar. '81** 27 11 0.8

* Data of the Ministry of Transport.

** Data of Kyushu Envir. Eval. Association.

68

.-.. . . . . . . . . .- - -* . . %.*.- .. -. . . .. M - A P.P . ... A .. .... . * .. -.. .* .- - -"- -*: -:" -" * "-": -;" "; -"-" " ""'". "-" *,.-..'.:..--,j-"
.* a

see. COW. li. Co. 4 1 3 4 -. 1 1 1 IA 

I A".

2K--

Figure 5. Vertical distribution of soluble ammonium-N and ortho-P *

K the Ist layer the 2nd layer

(/day) (0-l cm) F K (1-u2cm) F

C l/day' (pg/gwet)

0.10 K 100 0.10 -100 , F ,0%, (pg/gwet) 0

0o0 K , F %

0 '0 '1.05 b00 50 0.05 -- 50 .i- . 50~, 00 0 .-

0 0 0

8 10 12 2 4 6(month) 8 10 12 2 4 6(month)

Figure 6. Seasonal variation of degradable organics and

decomposition rate constant in sediment

Figure 7 shows the seasonal variation of DO in the upper and lower water

at the anchor site in Tokuyama Bay.

10 upper water

Figure 7. Seasonal variation of Z 6 -lowere r .. water

DO in Tokuyama Bay 4- w ii'.:i 11111-1

2 4 62 81 10 12

(month)

Maximum Specific Production

* Rate Coefficient (KPI) a.

Respiration or Decomposition

" Rate Coefficient in Water (KDI,2)

The following values were obtained concerning production and respiration

of phytoplankton. The maximum specific production rate is 0.1, 0.5, and

1.0 mg 02 /Pg chl-a/day in winter, spring, and summer, respectively. In contrast, the respiration rate coefficient does not have as notable a seasonal

variation. Though the data have a slightly large fluctuation, the constant

value of 0.1 mg 02/ Jg chl-a/day was tentatively adopted. Assuming that

69

*....... . -'.
chl-a/Pss = 0.8, and 1 mg of P is equivalent to 143 mg of 02# KP1 and KD1,2

are tentatively expressed as follows: KP1 = 0.56 (winter), 2.8 (spring),

5.6 (summer) (day-), and KD1,2 - 0.56 (day-).

Composition and Conversion

Factor of Phytoplankton in

Eutrophic Coastal Sea Area

The values of CODcr/N and CODcr/P of phytoplankton obtained are

17.5 (n = 15, r = 0.96) and 131 (n = 25, r - 0.84), respectively. Assuming

that the percentage of oxidizable fraction of phytoplankton for CODcr would be .

approximately 90 percent, the conversion factors TOD/N = 19.7* and

TOD/P f 143, derived from the generally prevailing formula C H 00N6 P "

106 2631

would also be available for phytoplankton in eutrophic coastal sea areas. The

TOD/COD is considered to be ca. 3 based on CODcr/COD - 2.63 (n - 9, r 0.99).

THE MODEL FOR PREDICTION OF P, DO, N, AND COD

CONCENTRATION IN A SIMPLIFIED CORE SYSTEM

Outline of the Model

Figure 8 shows the conceptual outline of the core model consisting of two

layers of water and two layers of sediment. The fundamental equations and the

explanation of symbols are given in Tables 2 and 3, respectively.

The mechanism of the nutrient regeneration or recycling system is

composed of several steps, as follows:

1) Assimilation of nutrient by phytoplankton.

2) Settling and sedimentation of phytoplankton.

3) Decomposition of phytoplankton in the upper layer of sediment and

regeneration of nutrient.

4) Adsorption and desorption or precipitation and dissolving of nutrient

between interstitial water and sediment.

5) Diffusion of nutrient toward the overlying water.

The flux of phosphate through the interface between sediment and water is

influenced markedly by the ORP condition of the sediment surface, namely with

the rise and fall of the oxidized zone. Therefore, the DO prediction cannot

be eliminated.

The DO in the surface water is changed with the decomposition or produc- .

tion of phytoplankton. It is also consumed with the decomposition of organic

matter in sediment. If sufficient DO is supplied to sediment, the oxidized

zone, i.e. ferric oxide, is formed by the reaction of DO in the lower layer of

* TOD = theoretical oxygen demand.

70

% ':-''-''-:'- .' "' ". '' ''i.' ". .''. "- '.:'"'. " " , "". '"- ' " -' -' ".-" "-... ' -" ." .: ', - . ." - , . -" " " . " " " .,... " " ,
upper water I-"-FI:'':: ~ -..:;--:Ft"- N .CI Z

- -. ... ..... '.. C . "

I 1 I 4 1 - ZS

CP',Z ==rP- ;-'-:-' C : -::::=Fk2 CPU CC2 Z2 I""''

"" I o I\ ....-- / ...."... - "

// E//FPA3 upper mud EP3 i F3 . i ...-FN CN3-EN3 Z3 I ,

CP31 ,P 

Z3 4

I Iluwer I mud

EP 4-CP4 -FP4. C4 -----------. C-4 Lr- EN4 Z4

EP.' FN4

Figure 8. Outline of the P, N, and COD model

water and ferrous iron in the upper layer of sediment. It is assumed that the

oxidized zone has a specific capacity to precipitate phosphate.

In contrast, if DO is deficient, sulfide, i.e. debt of DO, is formed and

reduction of ferric oxide occurs in the upper layer of sediment.

Setting of Various

Factors and Coefficients

The values of various factors and coefficients are listed in Table 3. In

adopting these values, both the experimental results described above and informative literatures were referenced. The sensitivity studies by the numerical model were achieved to evaluate those factors which are important but

insufficiently investigated.

Coefficients Having Seasonal Variation

If possible, the coefficients were expressed as a function of

temperature.

Temperature. Temperature data of the upper and lower water measured at

the anchor site in Tokuyama Bay from 1977 to 1981 were used and fitted with il7

sine and cosine curves (Figure 9). Temperature of sediment was assumed to be

delayed 20 days from that of the lower water.

71
TABLE 2. FUNDAMENTAL EQUATIONS #

Equation

Equation No.

(P) dCPI/dt-Dz(CP2-CPI)/(O.5Zs*Z1) .-PRO1*FP1 +KD1*FP1 +LP1/Zl 1

dCP2/dt-Dz(CP1-CP2)/(0.5Zs*Z2) +r*D(CP3-CP2)/(O.5Z3*Z2)

+r*KDB(Z31Z2)FP3 +KD2*FP2 -PRO2*FP2 (2)

dCP3/dt'-D(CP4-CP3)/ (O.5Zm*Z3) -D(CP3-CP2)/(O.5Z3*Z3) +KD3*FP3

+(KE3/v)*(EPA3-(CP3/a)) +(KR3/v)*(EPR3-1.3*b*v*MO) (3)

dCP4/dt-D(CP3-CP4) /(O.5Zm*Z4) +KD4*FP4 +(KE3/w)*(EP4-(CP4/a))

+s*KH*FP4 (4)

dFP1/dt-Rdz*Dz*(FP2-FP1)/(O.5Zs*Zl) +PROI*FP1-KICD*FPI-Ws*FP1/Zl (5)

dFP2/dt-Rdz*Dz*(FPI-FP2)/(O.5Zs*Z2) +PRO2*FP2

-KD2*FP2 +Ws*FP1/Z2 - Ws*FP2/Z2 (6) -

dFP3/dt-Ws*FP2/(r*Z3) -Wm*FP3/Z3 .-KD3*FP3 -KDB*FP3 (7) .

dFP4/dt-Wm*FP3/Z4 -KD4*FP4 ..4Kj*FP4 (8)

dFP4*/dt- ( -s) *KJH*FP4 (9)

dEPA3/dt. -KE3CEPA3-(CP3/a)) (10)

dEPR3/dt- -KR3(EPR3-1.3*b*w*Mo) (11)

dEP4/dt- -KE3(EP4-(CP4/a)) -KP*EP4 (12)

dEP4*/dt-KF*EP4 (13)

*1) PROI-KP1(CPI+n*FPI)/(CPo+CPI+n*FPI) nn'*CPI/(CP1+CPo') (a)

PROI1KPICCN1+n*FN1)/(CNo+CN1+n*FN1) nmn'*CNI/(CN1+CNo') (b)

The smaller value of the result from (a) and (b) is adopted

*2) C02<0; IcDB-0 Wc

C02>0; KDB-KDB'*C02/(C02+COo) (d)

(DO) dCO1IdtinDz(CO2-COI)I(O.5Zs*Z1) +Rop*PROI*FP1 -Rop*KD1*FP1

-Roc*KCD1(CC1-CCB) +KA(COsat-CO1)/Z1 (14)

dCO2/dt-Dz (COI-C02)/I(0.5Zs*Z2) +Rop*PRO2*FP2 - Rop*KD2*FP2

-Roc*KDC2(CC2-CCB) +~ 1,Rdm*D(CO3-CO2) /(0.5Z3*Z2)

-e*KM4P*M*CO2 -r*Rop*.fT3*Z3/Z2 (15)

dCO3/dt-Rdm*D(CO4-CO3)/(.5ZL.-Z3) -r*Rdm*D(CO3-CO2)/ (0.5Z3*Z3)

-Rop*KD3*FP3 -Kl.D*MO*CO3 (16)

dCO4/dt- -Rdm*D(CO4-CO3)/(0.5Zm*Z4) -Rop*KD4*FP4 (17)

dMO/dt- e*KMP*M*C02 +KMD*MO*C03 +KOM(MO'-(MO/po)) (18)

dM/dt- -e*KMP*M*CO2 -KMD*MO*CO3 -KAM(M'-(M/pa)) (19)

dMO'/dt- -KOM(MO' -(MO/po)) (20)

dM'dt- -KAM(M'-CM/pa)) (21)

*3) C02<0; KMP-O (e)

C03>0; KMD-mO (f)

(N) dCN1/dtu.Dz(CN2-CN)/(O.5Zs*Z1) -PRO1*FNI +KDI*FNI +LN1/Zl (22)

dCN2/dt-Dz(CN1-CN2)/(O.5Zs*Z2) +r*D(CN3-CN2)/(O.5Z3*Z2) b

+r*KDB*FN3(Z3/Z2) +KD2*FN2 -PRO2*FN2 -KN2*CN2 (23)

dCN3/dtinD(CN4-CN3)/(O.5Zm*Z3) -D(CN3-CN2)/(O.5Z3*Z3)

+KD3*FN3 +(KE3/w) (EN3-(CN3/a)) (24)

dCN4/dt-D(CN3-CN4)/(O.5Zm*Z4) +KD4*FN4 +(KE3/w) (EN4-(CN4/a)) (25)

dEN3/dt- -KE3(EN3-(CN3/a)) (26)

dEN4/dt- -KE3(EN4-(CN4/a)) (27)

FNi-Rnp*FPi (1-1l,2,3,4) (28)

dFN4*/dt-KH*FN4 (29)

(COD) dCCI/dt- -KCDI(CC1-CCB) +Dz(CC2-CCI)I(O.5Zs*Z1) +LC1/Zl (30)

dCC2/dt- -KCD2(CC2-CCB) -Dz(CC2-CC1)/(O.5Zs*Z2) (31)

TCOD1-CC1 +FP1 (Rop/Roc) (32)

TCOD2-CC2 +FP2 (Rop/Roc) (33)

72

%~q
TABLE 3. COEFFICIENT'S AND VALUES OF THE P, N, COD MODEL

FUNDAMENTAL EQUATIONS

Coefficient Explanation Value Units

CP1 Inorg-P cone. in the upper water layer 0.01 11g/ml

CP2 Inorg-P cone. in the lower water layer 0.03 Pg/ml

CP3 Inorg-P conc. in the upper sediment layer 0.2 Pg/ml

CP4 Inorg-P conc. in the lower sediment layer 2.0 ug/ml

FP1 Org-P conc. in the upper water layer 0.03 pg/ml

FP2 Org-P cone. in the lower water layer 0.02 pg/ml

FF3 Org-P cone. in the upper sediment layer 10.0 pig/mi

FP4 Org-P cone. in the lower sediment layer 2.0 Pg/ml

FP4* Humic-P conc. in the lower sediment layer 10.0 Pg/ml .. - -

EPA3 Adsorbed-P conc. in the upper sediment 0.8 ug/g dry

layer

EPR3 Stored-P cone. in the upper sediment layer 9.2 ug/g dry

EPA4 Adsorbed-P cone. in the lower sediment 10.0 ug/g dry

layer .

EP4* Residual-P cone. in the lower sediment 10.0 ug/g dry

layer

CN1 Inorg-N cone. in the upper water layer 0.2 Wg/ml

CN2 Inorg-N cone. in the lower water layer 0.5 pg/ml

CN3 Inorg-N conc. in the upper sediment layer 2.0 pig/mi

CN4 Inorg-N cone. in the lower sediment layer 5.0 Pg/ml

FN1 4 Org-N cone. in each layer Rnp*FP1 4 pg/ml

FN4* Humic-N conc. in the lover sediment layer 50.0 pg/mi

FP4* Humic-P conc. in the lower sediment layer 0.0 pg/ml

EN3 Adsorbed-N conc. in the upper sediment 8.0 pg/g dry

layer

EN4 Adsorbed-N cone. in the lower sediment 20.0 ug/g dry

layer

CC1 Alochtonus COD conc. in the upper 1.0 pg/ml

CC2 or the lower water layer 1.0 ug/ml 10.

CCB COD conc. of background 0.5 pg/ml

MO Ferric oxide conc. in the upper sediment 75 pg/ml

layer

MO' (inactive) 25 pg/ml

(Continued)

(Sheet 1 of 3)

73

° - . . ..- . . * ..... ,* o . , . ° ° . . 0 . . . . . .°. . .° . . .. - . , , . ° °,* .. °,
TABLE 3 (CONTINUED) * i

Coefficient Explanation Value Units

M Ferrous ion conc. in the upper sediment 75 ug/ml

la y e r , "

M' (inactive) 25 ug/ml'

Col Dissolved oxygen conc. in the upper 9.0 ug/ml

C02 or the lower water layer 8.0 lig/ml

C03 Dissolved oxygen conc. in the upper 0.0 1g/ml

C04 or the lower sediment layer -10.0 ug/ml-1 - -"'

KP1 Production rate coefficient of FP1 Fig. 11 day --

KP2 Production rate coefficient of FP2 0.3KP1 day - I

KDI Decomposition rate coefficient of FP1 Fig. 10 day

-I" De.%

KD2 Decomposition rate coefficient of FP2 Fig. 10 day KD3 Decomposition rate coefficient of FP3 Fig. 10 day I ''' 

KD4 Decomposition rate coefficient of FP4 0.1KD3 day

KDB' Decomposition rate coefficient by benthos 0.04 day

KN Denitrification rate coefficient 0.005 day-1

KCD1 Decreasing rate coefficient of CC1 0.02 day

KCD2 Decreasing rate coefficient of CC2 0.02 day -

-4 -1 KE3 Adsorption or desorption rate coeff. 1*10 sec

KR3 Precipitation or dissolving rate coeff. 1*10 sec

-7 -1

KMP Production rate coefficient of MO 3*10 ml* UIg /sec

KMD Diminishing rate coefficient of MO 3 ml0-8mi* 19g /sec

KOM Inactivation (activation) coeff. of MO 2*10 day

KAM Inactivation (activation) coeff. of M 2*10 day

KH Production rate coefficient of FN4* 2*10 - sec" .

KF Production rate coefficient of EP4* 1.5*10 - 7 sec - 1

KA Reaeration rate coefficient Fig. 12 cm/sec,

Dz Vertical mixing coefficient Fig. 12 cm /sec

D Diffusion constant in the sediment layer 0.5*1 cm /sec"

Ws Settling velocity of FP1 (FN), FP2 (FN2) 15 cm/sec

Wm Sedimentation rate of sediment layer 0.05 cm/day

COsat Saturated DO concentration Fig. 12 ug/ml .... -

CNo Michaelis constant of inorg-N for KPI,2 Rnp*CPo ug/ml

(Continued)

(Sheet 2 of 3)

74

*-. I- . .

* . .. . .. . . . . . . . . . . . . . .
F .'

TABLE 3 (CONCLUDED)

Coefficient Explanation Value Units

CNo' Michaelis constant of inorg-N for n Rnp*CPo' ug/ml

CPo Michaelis constant of inorg-P for KPI,2 0.02 ug/ml

-4 CPo' Michaelis constant of inorg-P for n 5*10- jg/ml

COo Michaelis constant of oxygen for KDB 0.1 ig/ml

a Adsorption equivalent constant 0.25 g/ml

w Volume/weight ratio of interstitial

water and dry sediment 1.6 mi/g

b Activity of MO 0.3 ._-

r Porosity of sediment layer 0.78

n' Maximum availability of org-N,P 0.04

s Decomposing fraction of FP4* 0.8

po Inactivation equibrium constant of MO 4.5

pa Inactivation equibrium constant of M 4.5

Rdm Conversion factor DM for oxygen/inorg-P 2

Rdz Conversion factor Dz for org-P/inorg-P 0.5

Rop Conversion factor O/P 143

Ron Conversion factor O/N 19.7

Rnp Conversion factor N/P Ron/Rop

Roc Conversion factor 0/COD 3

LPI Inf lowing load of inorg-P 0.03 .g*cm

LN Inflowing load of inorg-N 0.3 pg*cm/day

LC1 Inf lowing load of COD 5.0 pg*cm/day

ZI Width of the upper water layer 400 cm

Z2 Width of the lower water layer 100 cm

Z3 Width of the upper sediment layer 1.0 cm

Z4 Width of the lower sediment layer 4.0 cm

(Sheet 3 of 3)

75

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

'- * ..:--.- -" - . *-. '-- .' -".-°.. . .,''-' .'"."** *,.*.. ... '.. '-. -....... '.'.'*' .' .. ". " ." .'- "- ",. ".""*" . ' "
, .. 

Decomposition rate coefficients. Coefficients KDI, KD2, and KD3 were

determined by the following equations (Figure 10):

KDI,2 - 0.47 Exp [0.04(Tl,2 - 18)] (2)

KD3 - 0.025 Exp [0.052(T3 - 15)] (3)

where

KDI,2 - decomposition rate coefficient in the upper or lover water,

day 1

KD3 - decomposition rate coefficient in the upper sediment layer,

day 1

TI,2,T3 - temperature of the upper water, the lower water, and the upper ...

sediment, respectively, °C

da-1) . -

Production rate coefficient KPI (day Coefficient KP1 (Figure 11) was

determined by the following equation: _-

KPI -3.6 [S/(S + 120)] Exp [0.073(T1 - 18)] (4)

where S relative light intensity considering Oswald's solar energy and

weather condition (Figure 9).

Vertical mixing coefficient (Dz) and diffusion constant in sediment (D).

With reference to several reports, Dz and D were expressed by the following

equations (Figure 12):

Dz - 2.0 - 3.3 (iT - T21/6 (5)

D - 5 * 10 (1 + 0.04 T3) (6)

where

2

Dz = cm /sec

T1,T2 - *C

2

D - cm /sec

T3 =C

76

.. .... . . .., . ..: .. .. . . .... -.. .. . . .. , . . . .. - . . .-..- .. . , . ' . .

-" ... -' . *:,* :.. A " ' .k' , : -'" § . -',' .- -"> "-" "-" " "•-. , . :"•"- -. " .' -> K - " =, '-
04 w 44 4

01 W

4~

0 9: Z-4

m -0 >~i -4

C. 01c 0 

0i V00:

W~ 41 0 0u

to0. - 0

04.34

4-' -4~, - 4

00

cc 00

0 0 to~

0 P -, 

ca

0 4

4J CC >1 to0

Cd Z4

77
Method of Calculation

The fundamental formulas were reformed to differential equations and

solved by the explicit and rear method with dt - 30 min. The calculation was

evaluated up to 5 years. The stable results were then printed out concerning ,

the seasonal variation of DO, RN, RP, and other parameters.

Results and Discussion

Basic Results of Calculation

Figure 13 shows representative results obtained. The simulated seasonal

- variation of RN, RP, and DO concentration compares well with the data of RN

and RP shown in Figure 3 and DO in Tokuyama Bay shown in Figure 8. The dif-

. ference between the variation pattern of RN and RP is especially well described. The rise and fall of the oxidized zone are also of reasonable variation, in view of our experience, although the data have not been proposed.

Sensitivity Analysis on

Several Important Parameters

Effect of Rdm. Rdm is a parameter introduced to express the probable

effect of benthos, stimulating the flux of DO more than that of nutrients.

For the larger value of Rdm, the decrease of DO in late summer to autumn

becomes more severe. The rise and fall of the oxidized zone becomes more

striking as well. Rdm exerts little effect on the flux of phosphate (RP) or

RN (Figure 14).

Effect of KMD and KMP. The diminishing rate coefficient of the oxidized

zone (KMD) indicates an intense effect on RP, RN, DO, and on the variation of

the oxidized zone. For a small value of KMD, RP remains at a relatively low

level in summer due to the insufficient decrease of the oxidized zone. A

large value of KMD also lowers RP because of a delayed formation of sulfide in

early summer (Figure 15). Though the KMP value does not have as intense an

effect as KMD, for the smaller value the peak of RP delays toward autumn.

Effect of 8. Activity of the oxidized zone (i.e., precipitating capacity

6) intensely affects RP, RN, DO, etc. Especially for the larger value of 8,

RP is seriously suppressed and accordingly delayed (Figure 16).

Effect of KA and Dz. Although both values of KA (reaeration rate coeff.)

and Dz (vertical mixing rate coeff.) were varied to half or 1.5 times the base

value, notable effects on RN and RP were not induced. For the smaller values,

restoration of the oxidized zone causes a slight delay and the peak of RP

shifts toward autumn (Figure 17).

It should be noted that in all cases RN changes in almost the same manner

as RP, in spite of the fact that release of nitrogen from the sediment has no ,.. *.

relation to the oxidized zone.

78

-°. - .. .... .~r.*?.- , . ~Y~K K~i..>~~ -K ..
J9

Method of Calculation ..

The fundamental formulas were reformed to differential equations and

solved by the explicit and rear method with dt - 30 min. The calculation was

evaluated up to 5 years. The stable results were then printed out concerning

the seasonal variation of DO, RN, RP, and other parameters.

Results and Discussion

Basic Results of Calculation

Figure 13 shows representative results obtained. The simulated seasonal

variation of RN, RP, and DO concentration compares well with the data of RN

and RP shown in Figure 3 and DO in Tokuyama Bay shown in Figure 8. The difference between the variation pattern of RN and RP is especially well described. The rise and fall of the oxidized zone are also of reasonable variation, in view of our experience, although the data have not been proposed.

Analysis on -Sensit

Several Important Parameters

Effect of Rdm. Rdm is a parameter introduced to express the probable

effect of benthos, stimulating the flux of DO more than that of nutrients.

For the larger value of Rdm, the decrease of DO in late summer to autumn "-'.

becomes more severe. The rise and fall of the oxidized zone becomes more

striking as well. Rdm exerts little effect on the flux of phosphate (RP) or

RN (Figure 14).

Effect of KMD and KMP. The diminishing rate coefficient of the oxidized

zone (KMD) indicates an intense effect on RP, RN, DO, and on the variation of

the oxidized zone. For a small value of KMD, RP remains at a relatively low

level in summer due to the insufficient decrease of the oxidized zone. A

large value of KMD also lowers RP because of a delayed formation of sulfide in

early summer (Figure 15). Though the KMP value does not have as intense an

effect as KMD, for the smaller value the peak of RP delays toward autumn.

Effect of b. Activity of the oxidized zone (i.e., precipitating capacity

b) intensely affects RP, RN, DO, etc. Especially for the larger value of b,

RP is seriously suppressed and accordingly delayed (Figure 16).

Effect of KA and Dz. Although both values of KA (reaeration rate coeff.)

and Dz (vertical mixing rate coeff.) were varied to half or 1.5 times the base

value, notable effects on RN and RP were not induced. For the smaller values,

restoration of the oxidized zone causes a slight delay and the peak of RP

shifts toward autumn (Figure 17).

It should be noted that in all cases RN changes in almost the same manner

as RP, in spite of the fact that release of nitrogen from the sediment has no

relation to the oxidized zone.

79

~~~~~~....%.-.......,.....-........................x'.-..,:
00 w

-4 0 M

':'o o - a

r. u c 0

cc' W 0

-k 41 '-4 "

,- r' . Cu U 0

W-'o 0

c 0 cc

-.-

x x ac-

".'. i U "'

,.- .,'-3 ,0.O

,- 01

> 0 L

00 .

S'""', Cu

.44.

14~ Cu140 4

141 W -.

> 4

0 u

- C4

.0)

80)
,...,:

-- 1 102

33 4' --. .../. ., ." "

-4, ,. *

III .. ' .. * *1-'.

24681012:: :: :: 0 2 ' 4 6 81012"'"" 2 4 6 8 10 12 2 4-6.8"-0--

(nrmth) (month) s k

20 D120

... 0 4. 6 8 0 1

~~3.0

base 2.0....

,-.o 5 °. -.

30 •

024 :61%t I-:0~ 4 11

3.

base 2.0

of calculation r, 8"

10X..- --.

:0 12 -

42 6 8 1 1 2 4 6 8 10 12

0 rn nth) (nonth)

,~I x 0"

-- ., o-".,..

. x 1[ *

^ .

2 4 6 8 10 12 2 4 6 8 10 12".-"

txtO0 .a

./ ~~~base 3 x10"( "'"

Figure 15. Effect of KMD

81

'.C.L.- A- . : 
-30.

2 '4 '6 8 10 12 2 4 6 6 .10 12

(month) (mnnth)

-)30 8

.I

0. 15

base 0.30

0.38

Figure 16. Effect of B

x]03 10

-'or-'.

& -50-

2, '4' 6, 'S' 10 2 2 4 62

x102 (mnth) (nxmth)

620 - 9120

- .,* 

6 0

0. . . .

2 46 8012 2 46 8 10 12

(na~th)KAmja Dzmax

-3

base 4x 2 403 - 6 6x10 3

Figure 17. Effect of KA and Dz

82

... .- ,N.
Discussion

Until recently, the characteristic relationship between the interstitial

phosphate and the oxidized zone in surface sediment has not been well simulated. It appears that the main cause of the instability in calculation is

that the oxidized zone has been assumed to be formed by consuming DO from the

upper layer of sediment. Therefore, it is an important feature of this model

that the oxidized zone is assumed to be formed by consuming DO in the lower

layer of water. This assumption might not be unreasonable considering that

formation of the oxidized zone is highly stimulated by curling up to the overlying water.

It should be noted that composition of the organic matter is assumed to

remain constant in all stages of decomposition and that the decomposition rate

of organic matter is assumed to remain at the same level either in the aerobic

or anaerobic condition.

Many parameters exist in this model, including uncertain ones. Therefore, more extensive studies of experimental or numerical analysis have to be

conducted. For example, the upper limit of the oxidized zone, which is 200 mg

02/k, seems to be too small compared with the concentration of ferric oxide

that actually exists. The parameters KMD, b, or even relatively popular KA

and Dz and others admit more discussion.

Furthermore, the model might be expected to be simpler when applied to

practical assessments of water and sediment quality.

CONCLUSIONS

The fundamental components of this model are P, N, DO, and COD. Sulfide

is regarded as a debt of DO for simplification, and oxidized zone (ferric

oxide) as a source of DO. The oxidixed zone, which has a specific capacity of

precipitating interstitial phosphate, is assumed to be formed by the reaction

of DO in the lower layer of water and iron in the upper layer of sediment.

- Using this model, the characteristic seasonal variation of phosphate release from sediment to water, .nd the sEasonal changes of DO, COD, etc., were

well simulated.

ACKNOWLEDGMENTS

The authors gratefully thank the following contributors:

Takashi Hirajou, Mitsunori Amatani, Kikuo Miyake, Kazunori Matsumura, and

other members of our laboratory.

REFERENCES

1 1. Golterman, H. L. 1973. "Vertical Movement of Phosphate in Fresh Water,"

Environmental Phosphorus Handbook, E. J. Griffith et al. (ed.), John

Wiley and Sons, pp 509-538.

- 2. J~rgensen, S. E. 1983. "Eutrophication Model for Lakes," Application of

Ecological Modelling In Env )nmental Management, Part A, S. E. J~rgensen

' (ed.), Elsevier Scientific Piulishing Company, pp 227-282.

83 * ...
3. Kamp-Nielsen, L. 1983. "Sediment-Water Exchange Models," Application of

Ecological Modelling in Environmental Management, Part A, S. E. J~rgensen %

(ed.), Elsevier Scientific Publishing Company, pp 387-420.

4. Kumagai, M., and Nishimura, H. 1978. "Simulation of Oxygen Depletion in

Osaka Bay," Marine Science (monthly) No. 108, pp 791-795 (in Japanese).

5. Li, Y. H., et al. 1974. "Diffusion of Ions in Sea Water and Deep-Sea

Sediments," Geochim. Cosmochim. Acta., Vol 138, pp 703-714.

6. Lorentzen, M. R., et al. 1973. "A Long-Term Phosphorus Model for

Lakes," Modelling Biochemical Processes in Aquatic Ecosystems, R. P. Canale (ed.), Ann Arbor Science, pp 75-92.

7. Lung, W. S., et al. 1976. "Phosphorus Model for Eutrophic Lakes," Water

Research, Vol 10, pp 1101-1115.

8. Mortimer, C. H. 1941. "The Exchange of Dissolved Substances Between Mud

and Water in Lakes: J. Ecol.," Vol 29, pp 280-329.

9. • 1942. "The Exchange of Dissolved Substances Between Mud and

Water in Lakes: J. Ecol.," Vol 30, pp 147-201.

10. Nakata, K., et al. 1982. "Numerical Simulation of Eutrophication

Process in Coastal Bay by Eco-Hydrodynamic Model. (2) Coastal Bay Ecosystem Model," Bul. National Res. Inst. for Pollution and Resources,

Vol 11, No. 4, pp 41-46 (in Japanese).

11. Okuda, T. 1955. "On the Soluble Nutrients in Bay Deposits. (3) Examinations on the Diffusion of Soluble Nutrients to Sea Water from Mud,"

Bull. Tohoku Reg. Fish. Res. Lab., No. 4, pp 215-242.

12. Okugawa, K., and Somiya, I. 1983. "Simulation Analysis of Eutrophication by a Mathematical Model," Proc. JSCE, No. 337, pp 119-128 (in

Japanese).

13. Oswald, J. E. 1957. "Photosynthesis in Sewage Treatment," Trans. ASCE,

Vol 122, pp 73-105.

14. Standard Methods for the Examination of Water and Waste Water. 1975.

14th ed., APHA-AWWA-WPCF, Washington, DC.

15. Stumm, W., et al. 1970. "Phosphate Exchange with Sediments; Its Role in

the Productivity of Surface Waters," Advances in Wat. Pol. Res., Vol 2,

3-27/1-16 (S. H. Jenkins, ed.) Pergamon Press, Oxford.

16. Ukita, M. 1982. "Fundamental Study on Nitrogen and Phosphorus Sources

and Eutrophication Mechanisms in Japan," Thesis of Kyoto Univ. (in

Japanese).

17. Ura, M. 1976. "Mass Transport from Deposit Layer to Stationary Water

Region," Bul. Kyushu Inst. of Technol., No. 33, pp 21-30 (in Japanese).

84 . . '.
." K- .7 K-_ 7

EVALUATION OF THE FACTORS GOVERNING THE MOBILITY OF DREDGED

MATERIAL PLACED AT OPEN WATER DISPOSAL SITES

W. F. Bohlen

University of Connecticut

Marine Sciences Institute

Avery Point

Groton, Connecticut 06340

ABSTRACT

Long-term management of open water disposal areas

receiving dredged material requires an understanding

of the physical and biological factors affecting local

sediment transport. Within most continental shelf,

nearshore, and estuarine areas these factors display a

high degree of temporal variability with the majority """

of significant sediment displacements occurring during

aperiodic storm events. The short-lived nature of

these events establishes particular sampling constraints and favors the use of in-situ systems to

monitor transport-related processes. To satisfy these

constraints a bottom-mounted instrumentation array has

been developed and deployed. This array contains optical transmissometers to monitor suspended material

concentrations, temperature-conductivity probes, an

electromagnetic current meter, a wave gage, a lapsedtime camera and strobe system, and a sequenced mechanical water sampler. The entire system is controlled

and the resultant data recorded by a digital data logger. The unit is capable of unattended operation for

periods in excess of 30 days at sampling rates of four

scans of the entire array each hour. Reviews of

selected data obtained at several locations within

Long Island Sound reveal a range of hign and low frequency variations in sediment movements. Low frequency variations appear to be primarily the result of

biologically mediated factors while the higher frequency components occur in response to persistent

tidal forcing and aperiodic storm events. The latter

displacements appear to be nonlinear in character and

not simply related to storm intensity. In addition to .-

these temporal characteristics, array observations

indicate evident spatial variability associated

primarily with sediment characteristics and the presence or absence of near-bottom fluff layers. These

layers of organic-mineral aggregates appear to modify

the structure of the flow field affecting the sedimentwater interface and may serve to limit erosion and

transport. Determination of the dynamics associated

with these layers required consideration of the role

85

'.. ...
of the overlying water column as a source of materials

v " to the near-bottom areas. A system sufficient to pro- r' !

vide these observations is outlined.

INTRODUCTION e

The effective, long-term management of open water disposal areas intended

to receive dredged material requires an understanding of the variety of factors affecting local sediment transport. Such information is of particular

concern when the dredged sediments are associated with moderate to high concentrations of toxic contaminants. Present practice within the United States

requires effective containment of such materials by either placement within

areas characterized by low natural dispersion or through the use of special

handling procedures such as "capping" wherein the contaminated materials are

isolated from the adjacent water column by a layer of clean sediments (3).

Preproject specification of disposal site suitability and postproject monitoring of natural containment and/or the effectiveness of capping procedures are

complicated by the generally high degree of temporal variability characterizing the sediment transport system active within most continental shelf, nearshore, and estuarine areas. Within this coastal zone studies have shown that

the majority of significant sediment displacements occur during aperiodic,

*' high energy storm events (e.g., Bohlen (2)). Evaluation of the effects of

* such events on sediment stability within a given disposal area is difficult to

realize using standard shipboard sampling techniques due to the limited

accuracy of efforts to predict the times of storm occurrence and the inherent

difficulty of ship operation during storms. These factors, in combination

with the generally short-lived nature of storm-induced sediment resuspension,

* establish some particular sampling constraints and clearly favor the use of

in-situ systems sufficient to provide reliable, quantitative measurements of

sediment transport and associated governing factors over reasonably long

* deployment periods.

In early 1980 a bottom-mounted instrumentation array designed specifically to detail the effects of aperiodic storm events on the sediments placed

within active dredged material disposal areas was constructed and deployed

within Long Island Sound, a major commercial and recreational waterway along

the northeastern coast of the United States (Figure 1). Over the past 4 years

this array has been deployed at several locations within the Sound as part of

a Corps of Engineers sponsored monitoring program (DAMOS - Disposal Area Monitoring System). The data obtained during these deployments serve to document

the response to the near-bottom suspended material field to aperiodic storm

events as well as the lower frequency response to the more persistent tidal

forcing and the variety of seasonal factors including streamflows and biological activity. In addition, the observations provide initial indication of the

probable range of spatial variability characterizing the local sediment transport system and complement efforts to design optimum sampling schemes suffi- "-

- cient to permit calibration and verification of predictive analytical models.

The combination finds application within several areas of the overall management of the regional dredged material dispo A sites.

86

..... ,..........-...... ,...... .. ... ............ ,
.A,

/ /

! .~~...-'

~... A".-o" o

t. 0 t G - .""-

Figure 1. Long Island Sound. Circled areas designate !

study sites, . .

~ ~~~INSTRUMENTATION ARRAY ,..'".'

*Review of the variety of monthly data obtained via shipboard sampling ,.-..

over a period of more than 4 years in combination with experience associated

with the employment and subsequent servicing of a moored instrumentation array D .-

centered around a large surface buoy (1) indicates that detailing of the high" -"'"

frequency characteristics of the coastal suspended material field is best .- '.i

*realized using a bottom-mounted instrumentation array. This array would be -.- " self-contained with integral power and data recording sufficient to permit "'''?.

reasonably long-term in-situ observation of near-bottom suspended material ''' concentrations and associated hydrographic factors including water tempera- :

ture, salinity, and current speed and direction. Physically the array was to"'"'

*be free-standing and configured so as to minimize flow disturbance. To avoid --'. '

vandalism and potential upset of the array, surface buoys were not to be "?

*included and recovery routines were developed around an acoustic command and -"""-- location system. The array constructed to satisfy these criteria is shown in " -

Figure 2. b"

*C&L2

* As configured, the array consists of a digital control network and four

basic subsystems in combination with supplementary temperature and conductiv- "'"'-

self-recording package intended to monitor variations in the near-bottom pres- ""

sure field induced by tidal variations and the surface wave field. All instruments are mounted rigidly to the aluminum frame. As specified, the frame out- .

%1

line is designed to minimize flow disturbance while providing reasonable ..

87 sites

INSTRUMENTTION ARRA

Review o ~ ~ otl ~ ~ dt ~ band ~ i ~ hpoadsmln ~ of thait ~ ~ ~ ~° 

over hn4yasi ~ ~ ~ ~ ~ ~ obntinwt ~ ~ xeineascae ~ ~ a° peio ~ ofmr ~ ~ ~ ~ .

with usqet ~ ~ ~ ~ ~ evcn.fa.ordisrmetto ~ ~ ~ ~ ~ th mlyet ~ n ~ ra ~ ~~.°%' 
I7

I:'-'2."

Figure 2. Bottom-mounted

instrumentation

array

stability and ease of handling from a 20-m research vessel. The circular base

is approximately 2.0 m in diameter and is semicircular in cross section. The"'"

base is half-filled with lead. The remaining area is filled with concrete to

prevent lead contamination of the local waters or nearby sediments and to provide a rugged footing and some additional ballast for the array. This combination has proved to be extremely rugged and shows no signs of deterioration

despite 4 years of extensive use.

In the vertical the array frame is approximately 4 m in height. Three

aluminum pipes (-6 cm in diam.) forming the outer legs are bolted to the

periphery of the base and extended upwards to be joined by a circular horizontal plate. This plate provides a central strength member and serves to sup-

* port a section of heavy walled aluminum pipe (-10 cm in diam.) extending downward approximately 0.5 m and a support tie-rod configuration extending upwards

1.0 m. At their upper limit the tierods are joined by a second horizontal

aluminum plate. A stainless bail is bolted to the upper side of this plate to

provide a secure lifting point for the array. When completely equipped, housing all primary systems, the array weighs approximately 230 kg.

88
DATA LOGGER

- LOGIC CONTROL

-POWER -

II

PUMP OPTICALl CURRENT CA

lARRAY I METER :i:!:

COND. .:-:

TEMP.

Figure 3. Primary and secondary subsystems; bottommounted instrumentation array

The primary control of the array is provided by a digital data logger

(Sea Data Model 651-8). This unit, located near the top of the array

(Figure 2), also supplies power to select instruments and serves to record the

output signals from the current meter, optical array, and the temperature and

salinity sensors. These data are stored on magnetic tape cassettes with

capacity sufficient to permit sampling of all instruments four times each hour

for 36 days. The format of the stored data is system specific and requires

conversion prior to analysis. Conversion is accomplished using a Sea Data

Model 12A reader in combination with a Digi-Data magnetic tape drive. The

resultant nine-track tape contains data in an IBM compatible format and is

simply read using standard programming procedures.

The optical array is designed to provide direct samples of suspended

material concentrations at at fixed point above the sediment-water interface.

The array consists of two red-light transmissometers each mounted rigidly to

adjoining outer legs of the array (Figure 4). Designed to be relatively

insensitive to dissolved materials (particularly color-rich organics) and i

water matrix variations, each of these sensors provides an analog output proportional to the concentration of sediments suspended over a fixed 10-cm path.

Path length was specifid following an evaluation of instrument sensitivity

and examination of ambient suspended material concentrations and the characteristic variations expected at several locations within Long Island Sound.

Output characteristics were defined following individual laboratory calibrations of each instrument over a range of suspended material concentrations

prepared using natural sediments found in the vicinity of each deployment

89

...*.. ..**....* .
Figure 4. Optical sensornephelometer; bottommounted instrumentation

array

site. This calibration procedure is carried out prior to each instrument

deployment and repeated immediately following recovery of the instrument. The

results of this procedure, intended to permit correction of the initial

calibration for instrument drift and variations induced by biofouling of the

optical windows during the deployment, yield an algorithm detailing the relationship between output voltage and the equivalent suspended material concentrations in milligrams per liter. For the majority of the instruments used on

the array this relationship is only slightly nonlinear and can be adequately

described by a fourth order polynominal.

The current meter system consists of a two-axis electromagnetic current

meter (Marsh-McBirney Model 585 OEM) aligned so that the sensors are confined

to the horizontal plane. This unit, mounted at the lower end of the section

of perforated heavy-walled piping (Figure 2), is positioned to sense velocities at a point approximately 1.0 m above the sediment-water interface. Flow

direction is calculated vectorially using the output from each axis of the EM

sensor as referenced to the orientation of the array. The latter orientation

is referenced to magnetic north and is provided by diver observations obtained

during the immediate postdeployment check-out and reconfirmed just prior to

array recovery. For both speed and direction calculations output voltage is

converted to equivalent flow using a manufacturer-supplied algorithm.

The camera system mounted near the top of the legs, in the vicinity of

the central strength member (Figure 2), consists of a modified super-8mm movie

camera and a strobed lighting unit (Vivatar). Both components are mounted

90

° -*, .." -. °.'_°e_-t_- e

", " ," / ."." .-"3 °- "- -, '% - ,* ,€',. ,' .° . .' ,, '. " • "' . . '. -' - . '. . ', 4 . -' - . ", " '. -" ' ,' - " .* ". ". " " -" ". " '. " " ." "€ ". " - " ' ," ".
° .

separately in watertight polyvinyl chloride (PVC) housings. The front windows

for each unit are clear Plexiglas with no optical correction. Shutter speed

and lens aperture are adjusted to provide a sufficient depth of field to

permit simultaneous viewing of selected instruments on the array and the

sediment-water interface. This combination is of particular value within

efforts to resolve the cause or causes of anomalous peaks within the output of

the optical sensors and in addition provides direct visual evidence of an %

event's ability to erode or perturb the local bottom. This latter observation

assists in the resolution of the extent to which the suspended materials passing the optical sensor represent locally suspended materials or the product of

far-field erosion being advected past the array. These questions are often of

primary concern within efforts to manage a given dredged material disposal

area.

The final subsystem within the primary array consists of a drawn water

sampler intended to provide direct samples of the suspended material field to

supplement the optical data and to permit instrument calibration and possible

determination of the composition of the suspended load. The system consists

of an array of 12 syringe-like ports mounted concentrically around the central

support column just above the EM current meter (Figures 2 and 5). Each port

is spring-loaded and armed by means of a burn-wire strap. Sample sequencing

is controlled by a counting network sensing pulses from the central data logger. After receiving a predetermined number of pulses the circuit causes a

current to pass through the burn-wire rupturing the wire and activating the

selected sample port. The resultant sample can be either filtered or unfiltered depending on the port entry configuration.

Supplementing the primary array systems are two subsystems designed to

provide concurrent measurements of water temperature and salinity. Temperature is measured at two points on the vertical using protected thermistors

housed in watertight PVC pressure vessels. One unit is mounted near the upper

end of the stainless steel tierods restraining the data logger while the other

is attached to one of the vertical legs just above the annular base. Each

unit was individually calibrated against laboratory standards prior to

deployment.

Salinity is monitored using a single conductivity sensor mounted within

the perforated segment of the vertical heavy-walled aluminum piping just above

the attachment puint for the mechanical water sampler. The sensor consists of

a three ele-trode flow-through cell and associated electronics (Sea-Bird

Model 4-01). This combination provides a frequency output proportional to

conductivity. Conversion is accomplished using a counting network located

within the data logger. These counts are subsequently converted to equivalent

conductivity and then salinity using manufacturer-supplied algorithms.

On several occasions special purpose deployments required measurement of

surface wave characteristics coincident with the primary array observations.

To provide these measurements a self-contained digital wave and tide recorder

(Sea Data Model 635-li) was added to the array. This unit uses a quartz .-.

sensor to monitor the near-bottom pressure field providing an inherent resolution of approximately 0.05 cm in water depths of 20 m. The system is entirely

self-contained housing all necessary power and data storage and was rigidly

mounted in a vertical position adjacent to the array data logger. For all

measurements the unit functioned in a stand-alone mode. No attempt was made

91
7.77

k%

:" j Figure 5. Mechanical water 5. sampler

,-..-o %*-

to synchronize the internal clocks contained in the array data logger and the

wave sensor although both units were initialized at approximately the same

time. This timing arrangement appears satisfactory for the majority of the

observations required of the array.

SELECTED FIELD OBSERVATIONS

In January 1980 the instrumentation array was deployed at a location

along the western limit of the dredged material disposal area sited just to

* the south of New London, Connecticut (Figure 1). The array was retained at

vthis location for a period of approximately 24 months. Following refurbishment, after the recovery, the array was redeployed in April 1982 at a site

along the northeastern limit of the Central Long Island Sound disposal area

located approximately 10 km to the south of the harbor of New Haven, Connecticut (Figure 1). The initial observations at the central Sound site were

intended to complement efforts to define a study area to be used within the

Field Verification Program (FVP), an interdisciplinary research program -

sponsored jointly by the Corps of Engineers (CE) and the Environmental Protection Agency (EPA). At the completion of this site selection phase a long-term

monitoring program was initiated in August 1982. This program, designed

primarily to define the characteristics of the near-bottom suspended material

92

-47
r .,- 1%7 - - - .:::. 

, field so as to permit evaluations, both field and laboratory, of the range of

• .potential effects on the local benthic biological community, is still in progress. A brief review of some selected segments from these data sets provides

clear indication of the degree of temporal variability characterizing the suspended material field in the central and eastern Sound as well as information

concerning the response of the field to aperiodic storm events and some indi-

* cation of site-specific differences in the factors dominating material concentrations at each location.

Eastern Long Island Sound

For the initial deployment series the instrumentation array was placed --

along the western limit of the New London dredged material disposal area in

water depths of approximately 20 m. Circulation in this area is dominated by

the M2 tidal component with near-surface currents displaying a peak value of

approximately 75 cm/sec. Freshwater discharge from local streams is small and

generally exerts a minimal influence on the regional water density structure

and associated circulation. Surface waves can affect local circulation and

*. mixing with influence varying primarily in response to wind speed and direction. The wind field characteristic of the eastern Sound varies seasonally

with winter months dominated by northwesterly winds and summer months by

southwesterlies. Occasional high energy storm events can occur throughout the

year although maximum frequency of occurrence is usually confined to the late

fall-winter-early spring period.

Since approximately 1975 the New London disposal area has received more

than 5 x 10 6m 3 of dredged material. The majority of these materials were - removed from the Thames River and consist of fine-grained cohesive sediments

* having mean grain sizes of approximately 62P. Materials are generally removed

". using a clam-shell bucket dredge and placed via hopper barge.

Data developed during the initial deployment period (January 1980) show

average suspended material concentrations at the study site ranging from I

'* to 3 mg/k. This progressive increase in average concentration over the 10-day

period appears to be primarily the result of material accumulations on the

windows of the optical sensors rather than any persistent increase in actual

ambient levels. Concentrations vary about this mean by approximately ±1 mg/"

at rates essentially coincident with the twice daily tidal period (Figure 6).

These variations display only minor sensitivity to the monthly spring-neap

cycle.

In addition to the low frequency variability associated with local tidal

cycling, the suspended material record displays a number of high frequency

variations during which indicated concentrations significantly exceeded the

average background levels. Such perturbations occurred on Day 2 (-26 hr), o

Day 3 (-76 hr), Day 7 (-198 hr), Day 10 (-240 hr), Day 11 (-260 hr), and

Day 12-13 (-300 hr). With the exception of the event which began on Day 7,

these perturbations were short lived and persisted for less than 5 hr. Review

of the primary factors governing suspended material concentrations in coastal

waters including streamflows, winds, and tidal currents indicates that, for

the period of observation, only wind-induced factors and tidal currents Wv

displayed variability sufficient to affect the observed perturbations.

Streamflows remained essentially constant throughout the period and were

93
I~i I

NEPHELOMETER NO. 2

DAISY DEPLOYMENT NO. I

NEW LONDON SITE

. TIME ZERO- 1050 JAN. 4,1980

0

4. , 

0u Z2

1.00.

";W 

, owl,,, 

0.0 ..

0.00 4s0.o 0 e4o. , 2. .o 2%0.0 aio.o sF.o

so .

C 0 .

0

0- 0.54.0 100 b

IIJ

TI.0 INHOR

0.00r .tu data from bott o-oune instrumenta-*

"- | i ii I So

aeidcvrain, seea of whc aecicdn ihteosre

-. hi0 4 0,:: .

in sped 0ru.b400 i 0.0 ti on 240 mji 0 thes0 TI E IN HOURS ,

L-: Figure 6. Output data f roma bottom-mounted instrumenta- :.

': varition artion Eastern array Long and Island associated Sound wind deployment, speeds: -.'-

' ". . ~J a n u a r y 1 9 8 0". -

characterized by below average discharge. The wind and tidal current speed

irecords for the deployment period (Figure 6) contain several prominent

aperiodic variations, several of which are coincident with the observed

~variations perturbations in suspended material concentrations. The majority of these are contained within the wind record. Only during the Day 7 ~~(-198 hr) event was there a significant variation in the tidal current system. :- _ Wind speed peaks are clearly associated with the Day 3 and Day 7 events with ,= *" secondary smaller peaks evident during the Day 2 and Day 1i events. The ..

I -. ' remaining perturbations within the suspended material record show little rela- :'.

*. tion to tidal current or wind speed and appear to be primarily the result of

biogenic detritus, including seaweed and swimming and planktonic organisms

passing through the sampling volume of the optical sensors.

Each resuspension event displays some significant similarities and , differences. Events induced by relatively low wind speeds (<30 km/hr) tend

94

.. .. -.. ... .....'. .. ...'. .'.. --',--- .' .' .. . _'.::..,:i ::, " "- "-" " " " - " - '-"-' - " " ''
RO-R163 769 MNAGREMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC 2/S SUBSTANCES: PROCEEDINGS 0.. (U) CORPS OF ENGINEERS FORT BELVOIR VA HATER RESOURCES SUPPORT CE. T R PATIN UNCLASSIFIED OCT 85 F/G 13/2 WL

I'-hh LEEILI
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/ AJ

11W

IEIII1

III1' II_ -1

MICROCOPY RESOLUTION TEST CHART -

NATIONAL BURFAU OF SIANDARDS I %)3-A

- I-

°- ..

: , .... . .... _,. ... .. ,. .. . . . . .... .. .. . . . . .. ., ...-... ... ,.., .. . :., .... . .. , .,l-, ,. -. .l... -,, .
to appear as a well-defined peak essentially coincident in time with the onset

of maximum tidal speeds. Increasing wind speed above 45 km/hr induces only

minor increases in the magnitude of resuspension but favors a significantly '

longer duration (e.g. compare Day 2 to Day 7). Even during the longer duration events however the pattern remains "spikey" with each peak essentially --. 2

coincident with the tidal speed maxima. This continuing coincidence suggests

that the observed * resuspension is not simply ~a the result of wind-induced factors but is rather due to the combined effects of winds and tidal currents.

The observations suggest that the sediment-water interface in the study area

is in essential equilibrium with the prevailing tidal stream and experiences

significant disturbance only during times in which available transport energy

is significantly increased by the added influence of wind-stress-induced

factors.

In addition to the onset of significant perturbations, the suspended

material observations also show significant differences in the response of the

sediment transport system to given wind stress events. This difference is

particularly evident in comparisons of the Day 3 with the Day 7 events and

appears to be primarily the result of differences in the duration of the

associated wind events. The remaining characteristics are essentially similar

with both events displaying peak speeds of approximately 60 km/hr and a predominantly south to southwest directionality. The duration for the above

average wind speeds for the Day 3 event was approximately 35 hr. For the

Day 7 event high velocity winds persisted for approximately 55 hr. In additiuti, winds during this latter period displayed more intense high frequency

variability sufficient to produce a generally more energetic system.

Differences in wind duration and energy levels will affect primarily the

stress-induced wave field with some secondary influence within the associated

mass transport system. At equivalent peak speeds, longer duration favors

generatlon of larger amplitude, longer period surface waves. The observed

response suggests that the transport field in the eastern Sound is particulariv sensitive to this generalized behavior. This sensitivity is most

probably the result of the relatively sheltered nature of the Sound resulting

from its long, narrow configuration. Such a form serves to significantly

reduce the effective distance or "fetch" over which wave generation occurs

making the surface wave field particularly sensitive to wind direction and

duration. As a result, slight variations in dominant wind direction and event

duration can produce significant variations in surface wave characteristics

and associated material resuspension. This variety of observations complements determination of the cause of the apparent nonlinear response of the

suspended material field in the eastern Sound to aperiodic forcing noted in

previous investigations (2) and assists in the selection of the proper modeling form to be used in the analytical prediction of system response to the

passage of high energy storm events.

Central Long Island Sound

Within the central Sound the instrumentation array has been deployed near

the northeastern corner of the New Haven dredged material disposal area (Figure 1) since August [982. This location represents the primary study site

within the open water aquatic phase of the FVP. Bottom contours in the vicinitv of the deployment site are essentially planar and display average water

depths of approximately 20 m. Circulation in the region is again dominated by

95

..................................................... -. .. . . * -*. . - .. - . .,*-
b- V

the M2 tidal component with local streamflows representing a generally minor

influence. The resultant current field is less energetic than that found

within the eastern Sound and displays maximum speeds that are typically less

than 50 cm/sec. Since the initiation of FVP this site has received approximately 70,000 m3 of fine-grained sediments dredged from within Black Rock

Harbor, a small embayment adjacent to Bridgeport, Connecticut (Figure 1).

These materials, characterized by a generally moderate to high water content

and a low density of infaunal organisms, were removed using clam-shell bucket

techniques and placed at the disposal site by a hopper barge. Precision

placement techniques resulted in a coherent conical mound centered on the

disposal buoy at the completion of the dredging phase.

Observations provided by the instrumentation .array indicate that the

suspended material concentrations in the areas adjacent to the FVP site are

typically higher than those observed in the eastern Sound with values averaging approximately 6-8 mg/t. In addition to higher average values, the optical

data also indicate a higher degree of temporal variability in the central

Sound suspended material field. As shown in Figure 7, a representative set of

data obtained just prior to the initiation of dredged material disposal, this

variability is reasonably persistent with peak concentration values exceeding

the average by nearly a factor of two. This pattern persisted after the

completion of the disposal operation with only minor perturbations observed

during the immediate postdisposal period.

DEPLOYMENT NHDAO9

FP DISPOSAL SITE NEW HAVEN

IN 0740 EST 4//0i3

-10.0 -.

U)

-J0

U) 9.0

0.0

7.0 II I

0 7 40 go- 80 100 126-- 140 ROO 180

HOURS

Figure 7. Suspended material concentrations, central Long Island

Sound, 1983

The observed variations in suspended material concentrations display a

clear correlation with the local tidal phase. In contrast to the eastern

Sound distributions, peak concentrations are typically found during periods of

96

.....* ."~ . . .. . .* .- ~ * .. '.. . . . . . . . . - - . .... . . -.- .-.-.. ., -.-. ,- .- :;;
low velocity with concentrations characteristically decreasing as speed

increases. This response suggests that the near-bottom suspended material

field in the central Sound is dominated by an assemblage of fine-grained

materials with settling characteristics that favor the formation of a "fluff

layer" that alternately disperses and consolidates over the course of the

tidal cycle. These observations are consistent with those discussed in previous studies that have noted the presence of high concentrations of organicmineral aggregates within the near-bottom waters of the central Sound (4).

The source of the materials forming the fluff layer is difficult to

accurately specify. Observations during the spring of 1983 intended to determine the importance of the water column relative to the sediment-water interface indicate a progressive variation in light attenuation over the vertical

with the water column divided into two layers by a pycnocline located approximately 10 m below the water surface (Figure 8). Within the lower layer light

LIGHT ATTENUATION (%) TEMPEtRATURECC) SALINITY ( %4 ,:..

. I? . P .2I .42 .O 6q 2P2 32 5 2 0 2 02 

/ 0.

, .I

15.. ,I "

Is IslIlt

\ \ !LONG ISLAND SOUND

20-i 20- ,fVP SITE, -

(1045) APRIL 22, 1983

(200711 1(170-n /

(1845)

2s4 251

Figure 8. Selected hydrographic data, central Long Island Sound,

1983 (all times indicated are EST)

attenuation progressively increased as flow velocity decreased, a trend

generally consistent with the observed increase in suspended material concentrations at low velocities. Although these light attenuation patterns fail to

display a well-defined cross-over point indicative of a simple mass balance

over the vertical, they appear to be reasonably representative of a system in

which continuing erosion from the sediment-water interface is limited by a

variety of factors and may be of secondary importance as a source of materials

- to the fluff layer relative to the overlying water column. For the study site

the factors limiting erosion of the sediment-water interface include the

97 ° ,- - o

.-. ' . .. . ..-. . . . . - . . -. . ... -- . -. " .. •v .. -. -.- ' .' - '. -.- ' '. .-' '.. -'' .- '. - --. .'- '.., -.. " ..- .
primary sediment characteristics, biological stabilization, and possible dissipation of tidal energy, sufficient to effectively reduce the boundary shear .4

stress, resulting from the present of the fluff layer. Surveys of interface

characteristics using a specially designed camera system (4) in and adjacent

to the disposal site indicate reasonably high compaction rates in the placed

materials and characteristically high densities of burrowing organisms immediately before and very shortly after completion of the disposal operation

(Figure 9). These preliminary observations suggest that the presence of the

fluff layer may represent the primary factor controlling the short-term

erodibility of the sediment-water interface. Studies intended to resolve this

question are presently in progress.

/13 83- 200S

,~ . bFigure 9. Interface camera profile, central

Long Island Sound FVP site, 1983

Beyond the tidal frequencies the central Sound observations provide only

* limited indication of the character of system response. The 1982-1983 deployment period was characterized by an absence of significant storm events. Maximum wind velocities were associated with the prevailing westerlies and none

" were sufficient to measurably perturb the near-bottom suspended material

field. The present extension of monitoring through 1984 will hopefully

provide a more typical range of conditions and permit initial examination of

the response of the transport system to storm passage under varying seasonal

98

. . ...--.. . .
conditions. Such observations would nicely complement the above studies of

the effects of the fluff layer on the erodibility of the sediment-water

interface.

DISCUSSION

The observations provided by the instrumentation array show the nearbottom suspended material field in eastern and central Long Island Sound to be

characterized by a moderate to high degree of temporal variability. These

variations are typically short lived and essentially confined to the period of

the dominant forcing system. In the case of the tidal cycle this period is

essentially coincident with the M2 component and the semimonthly neap-spring

* cycle. For significant storm events the perturbation period increases typically approaching the duration of the storm. Tidal effects continue to appear

within these later events, however, with the superposition evident within the

observed suspended material distributions providing evidence of the significance of wave-current interactions within these storm-induced perturbations.

The temporal characteristics displayed by the near-bottom suspended

material field suggest that the majority of the sediments in suspension have

high settling velocities despite their fine-grained nature. This evident

enhancement in settling velocities, most probably resulting from a combination

of biologically mediated aggregation and concentration/neighbor effects, complicates sampling and establishes criteria that are often difficult to satisfy

using standard shipboard sampling procedures. Observations at both study

sites indicate the utility of relatively high-frequency, in-situ sampling,

particularly within efforts to develop analytical modeling schemes. Both the

variations in system response to wind stress events differing only in dura- - tion, observed at the eastern Sound site, and the effects associated with the

presence of the fluff layer, found in the central Sound, would be extremely

difficult to assess using a few discrete samples.

In addition to the temporal characteristics the observations provided by

the instrumentation array assist in the resolution of various spatial characteristics. The available data suggest that these differences are primarily

the result of the presence of a fluff layer overlying the sediment-water

interface within the central Sound. As noted, this layer may serve to modify

near-bottom shear stress levels and thereby effectively armor the sedimentwater interface or shield it from progressive erosion. Test of this hypothesis requires determination of the relationships between the fluff layer and

the overlying water column. The addition of this vertical coordinate adds a

sampling criterion that cannot be simply satisfied using the present instrumentation array. For the moment standard shipboard procedures are being used

to obterin selected profiles over the vertical. If these data cannot disprove

the importance of the water column as a source of materials to the fluff

layer, 'uture observations will most probably make use of a sensor array

contained within a buoyancy capsule tethered to the bottom-mounted instrumentation array. The buoyancy system would, on command, cause the sensor

package to migrate over the vertical, obtaining nearly continuous samples

during transit. The resultant data could be stored internally, passed to the

master data logger on the instrumentation array, or telemetered to a shore

station during the short interval during which the capsule penetrated the

air-sea surface. The measurements provided by such a system would provide a

valuable extension to our present two-dimensional measurements of sediment

99 . -.

4 . -
transport and in addition may serve to complement a variety of other studies

including both physical and chemical characteristics. The technology required ,

for this system is presently available. Similar vertical cycling systems have

been used in open ocean studies although none have been applied in studies

specifically related to sediment transport. The observations obtained within

Long Island Sound suggest that within the more variable near-shore areas such

systems may prove of particular value and significantly extend the utility and

capabilities of the existing bottom-mounted instrumentation arrays. Such an

extension can only improve our abilities to monitor and model the sediment

transport processes affecting materials placed within coastal open water

disposal areas.

REFERENCES

1. Bohlen, W. F. 1974. "Continuous Monitoring Systems in Long Island Sound:

Description and Evaluation," Proceedings of IEEE Int'l. Conf. on Engineering in the Ocean Environment, Halifax, Nova Scotia, Aug 1974, Vol 2, r..-

pp 61-69. ,. •..

2. Bohlen, W. F. 1975. "Suspended Material Concentrations and Transport in

Eastern Long Island Sound," J. Geophys. Res., Vol 80, No. 36,

pp 5089-5100.

3. Morton, R. W. 1983. "Precision Bathymetric Study of Dredged Material

Capping Experiment in Long Island Sound," Wastes in the Ocean, Vol 2,

Dredged Material in the Ocean," Kester, D. R., Ketchum, B. H.,

Duedall, L. W., and Park, P. K., eds., Wiley and Sons, New York,

pp 99-124.

4. Rhoads, D. C., and Cande, S. 1971. "Sediment Profile Camera for In-situ

Study of Organism-Sediment Relations," Limnology and Oceanography, Vol 16,

pp 110-114.

5. Rhoads, D. C., and Yingst, J. Y. 1978. "Seafloor Stability in Central

Long Island Sound," Parts 1&2, Estuarine Interactions, Academic Press, '.

pp 221-259.

1.0.. .

-. - .:

100 "-

•.. ° . ..
NUMERICAL PREDICTION ON THE EFFECT OF PHOSPHORUS

RELEASE CONTROL BY SEDIMENT DREDGING

T. Horie

Chief of Purification Hydraulics Laboratory

Hydrodynamics Division

Port and Harbour Research Institute

Ministry of Transport

1-1, 3-chome, Nagase

Yokosuka, Japan, 239

ABSTRACT

This paper discusses the development of a numerical model on phosphorus behavior in sediment, behavior that is closely related with internal production

of phytoplankton. Several assumptions are applied to

the model formulation such that PO4-P release is

caused by the dispersion in interstitial water, and

that PO04 in interstitial water is determined by the

decomposition and dissolution of organic substance in

sediment, adsorption or desorption to sediment parti- - cles, and dispersion. Each process included in the

model was confirmed by field experiments or laboratory

tests. Sediment thickness effective to release was ... -

decided as 60 cm, considering settling velocity, vertical distribution of substance in sediment, etc.

Seven layers were totally prepared for the analysis.

The model verification was performed to the annual

verification of PO4 -P release rate, SS accumulation

rate, I-P, O-P in sediment, and PO4 -P in interstitial

water, by applying the model to the sediment sampled

at off-Nishinomia in Osaka Bay. Furthermore, this

model was applied to the prediction for the cut-off

__ effect of PO4 P release rate and its duration time.

According to this analysis, in the case of 50-cm

dredging thickness, the cut-off effect of PO4 release rate was estimated to be 70% just after the

dredging, 50% after 20 years, and 20% after 50 years.

INTRODUCTION

Organic pollution in seawater is mainly due to the effluent, the internal

production, and the release from sediment. These processes greatly influence

101
the seawater quality and complicatedly interact. Release flux from sediment

is affected by sediment property, temperature, dissolved oxygen, deposited

substances supplied from seawater, etc. According to the in-situ or laboratory experiments, the influence of settling substances on release flux is not

negligible, and occasionally plays an important role. For the complete understanding of water quality distribution in seas, the mechanism of release from

sediment should be analyzed with its connection to the influence of settling

substances.

The release from sediment is also influenced by seawater quality as well

as various processes in sediment. Therefore, the release mechanism should be

simultaneously analyzed with seawater quality. However, under the present

situation where the release mechanism is not well understood, it is necessary

to first formulate the release process, then confirm the model reproducibility, and finally combine the release model and the seawater quality model.

Because of the above, a mathematical model on phosphorus behavior is

formulated, based on water quality, sediment, interstitial water, and release

rate data obtained at off-Nishinomia.

The release control effect due to dredging was numerically investigated

by using this model. I.."-

MATHEMATICAL MODEL

All the essential materials composing organics, as well as temperature

and illumination, can influence marine eutrophication. By limiting the group

to chemical aspects, nitrogen, phosphorus, carbon, iron, manganese, vitamins,

etc., are more influential. Among these elements, iron and manganese are

sufficiently supplied from sediment. Therefore, the content of nitrogen and

phosphorus is more sensitive to the eutrophication.

With the consideration of water quality distribution in Osaka Bay, the

following assumptions and approximations are adopted:

a. PO4 P release (R) is caused by dispersion in interstitial water.

b. PO4-P concentration in interstitial water (C*) varies with bacterial

decomposition and dissolution of sediment organic substances,

adsorption to sediment particle, and release into seawater.

C. PO4-P is allocated with a certain ratio (a) into interstitial water

and sediment particles.

d. PO4-P production in sediment is caused by the decomposition of newly

accumulated substances and existing sediment.

e. The O-P supply from seawater to sediment is carried by settling

substances, which is regarded as conservative.

f. Phosphorus behaves in the sediment within a certain depth.

102

................................
P0. 4-P in overlying seawater mixes with lover seawater in a certain

exchange ratio.

The mathematical model formulated with the above assumptions is illustrated in Figure 1. (Each process shown in Fig. 1 is expressed by Equations 1

through 5).

0-P in n-th layer:

t+1 (ot op X At) OP opt DSX (OPoA + DSL x -P: 2 xOp + pt(1 x 

decomposition accumulation agitation .

accumulation rate relaert

S( mg/m/ay (mg/m /day)

I E, ,n spersion

Ist laYeOr 0-P decomposition dissolution inlterstitial

(thckessN, ng/g, adsorption(m/

disturbance Iaccumulation 11accumulation , dispersion ~~~~~~~* -- ---------------

disturbance

0-Pm/g decomposition dissolution interst itial

g/g)ai P04 - 2nd layer lm/Iadsorption Img/1 (thickness H-2)

I- P adsorption

(mg/g) /desorption

I dispersion

disturbance accumulation ---------acmlto n lh lyer Idisturbance

same below

Figure 1. Illustration of the model on phosphorus

behavior in sediment

I-P in n-th layer:

nn n n n- n, n-I n +I (2 In + t+ +~(~t- 1 t~DL (~ P + P f

ad-, de-sorptlon

allocation accumulation agitation

103
_7r 77 V 7 W;.7 .77IT1 -

C* in 1-st layer:

C+ - I Ct2 * I

t t w C*l 1 at (3)

1 1 1 1 2 .

-cr Catl. I +-. x x! T q + ' " + i;xox( l +H)/2j 2 1 t ()".'

allocation ad-, de-sorption dispersion

C* in n-th layer:

t t.-

I,.• , .

I r~~ I C*O+ - . -.-..

-U- +i~ , .. x I At" " 

.tC t x ,I L t L q t +it D - 2 + I,'+ (H +- )/t ,n (

C in overlying water:

V

'= (Ct + x R' At x DL (5)

where

DS = accumulation rate

DSL = agitation factor

D = diffusion coefficient

= interstitial water ratio in dry sediment

= void ratio

H = layer thickness

a - adsorption-desorption ratio of produced PO4-P

q = adsorption or desorptlon rate

t = time

n layer

104

* ... - *...* . . . . ..
Z ' .- - V7 I - 1 7 - .- -- 

The details of these equations and parameters are explained in the

foregoing sections.

FORMULATION OF EACH PROCESS

Effective Thickness of Sediment and Layer Partition

The analysis of each parameter included in Equations 1 through 5 was .'

performed on sediment sampled at a certain point in Osaka Bay. Figure 2 shows

the experimental release rate results of sediment taken by a core sampler

200 mm in diameter. These experiments were conducted at 25°C under anaerobic

conditions. According to these results, release rate is higher in layers less

than 50 cm deep, and quite low in deeper layers. Matsumoto and Yokota (5)

estimate an accumulation rate of 0.18-0.16 cm/year in the inner bay, and an

210 annual mean of 0.41 cm by using Pb vertical distribution in sediment

(Figure 3). For this reason, the effective sediment thickness to release is

taken to be 60 cm, which corresponds to an accumulation time of 150 years.

1?- 25 L

F-I Osaka

SE057) Ko te Ook

0013 075 23~ sf23 st25 s144 st331 6 " "3

25*C unaerobic 0-30cm

for 20 days 58c~(rtt

0-30cm layer

Figure 2. PO -P release rate in Osaka Bay 4

Kobep~ 40 o: b 0'''' "'

Figure accuulationA'"z"" .- 5m026 "

Figure 3. Distribution of 3re 5"

accumulation Awao" 1061. f

rate (cm/year) " 2 0 012 12 

0 5 10 20

~ (5O- -i - 13500 10 20-

The vertical structure of sediment is schematically shown in Figure 4.

The very thin surface layer consists of fresh deposits with high water content "''

and easily mixes or moves along the surface. This layer has high T-P and

PO4-P production rate is great. This layer plays a major role in nutrient

105

. . . . .-
.6

P p- P 4

_-P content release rate M__

Sediment agitation layer ('' fresh depsit} 3.2 high high ag t ti n la e

-' 3 2 h i g by wind up

upper 0 agitation by wavesbenthos

"" 08and fish

Sediment 0.6 non-agitation layer

-" low low comparatively stable

lower 4

no distinguishable movement

Figure 4. Vertical structure of sediment

release. In the lower layer, however, the water content decreases asymptotically under long-term consolidation, and less vertical agitation occurs. The

T-P content and PO 4 -P production rate in the lower layer are lower than in the

upper layer. In the middle layer, water content is nearly constant, and the

. sediment in the upper layer is agitated by waves, fishery, and benthos activity. Agitation was presumed to occur within 8-30 cm in depth, according to

210pb., -:

the vertical distribution of excess Pb by Matsumoto and Yokota (5). Kikuchi (4) concludes that sediment disturbance by benthos is limited within 20 cm

in depth. Considering the results, the upper 15 cm in depth was regarded as

the agitation layer in this model and assumed to be completely mixed in 4 years.

Thus, the effective thickness of sediment, 60 cm, was divided into an

agitation layer of 15 cm and a lower nonagitation layer of 45 cm. Furthermore, the upper layer was divided into four layers and the lower layer into

three layers.

The first layer was defined as the surface layer of 0 to 0.41 cm in

depth, which corresponds to a 1-year deposit by Matsumoto and Yokota (5). The

second layer was defined as 0.41 to 5 cm in depth where sufficient data were

obtained by observation. The agitation layer lower than 5 cm was divided into

the third and fourth layers. The nonagitation layer of 15 to 60 cm was

divided into the fifth, sixth, and seventh layers. These layer partitions are

illustrated in Figure 5.

The PO -P release processes were analyzed by Equations 1-5 for the seven 4 layers.

Settling and Accumulation

Accumulation rate is related to settling rate as follows:

0- x 365 (6) sediment ratio unit weight .x35(

where

T accumulation rate (cm/year)

S settling rate (SS g/m-/day)

106
00V

accumulat ion accumulation ferm

thickness (cm) (year')

514 ,.tayr2-nd laye - 12.5 V

6-th layer '5-th layer 4.

7-th layer

60 - 1463

(on th~e assumption

of 0.41 cm/year of

accumulation rate)

Figure 5. Layer partition of sediment

3

By substituting sediment ratio 0.29 ,unit weight =1.12 g/cni and

2

T =0.41 cm into Equation 6, accumulation S is calculated by 3.9 SS g/mI

day. Assuming settling SS for t days as AS t, stock in the first layer as

Si t and allowable capacity of SS in the first layer as TSL, then the stock

in the first layer is counted in the following manner (see Figure 6):

sit 51 1 + AS (for Sl1 < TSl) tt

sit = TSL

St-AS' + r 1 AS > TS t tA i Lv +A leTS1

2-nd layer rS2

(a) Shi i.ASt>TSi

-as,

2-nd layer S2

(b)SiroASZSs

Figure 6. Estimation of SS stock

107

*1' . .* . . . . . . . . . . . .. %
pr =--r -- V- - 2 f . - - ---- -.- . w -- - -= . -. , - . - - .. j L

V _

The SS stock in the other layers was counted in a similar manner. In the

analysis, only SS was related with accumulation rate, and O-P and I-P were

transported by SS. O-P and I-P contents in SS were considered to vary with

dissolution and adsorption/desorption.

PO4-P Production

PO4-P production in sediment is mainly due to the bacterial decomposition

of organics. Considering the property of sediment shown in Figure 4, PO4-P

production was estimated to both the fresh deposit and the old sediment for

the first layer, and to only the old sediment for the second through fourth

layers. The relation among SS, O-P, and PO-P production in sediment is

illustrated in Figure 7.

early stage time elapse ? °.

0 O5-

Q', -',....

,- total SS,. - ,

0 0 -P" -''"

PO-P production rate

Figure 7. O-P decomposition and PO4 -P production .

4..

The SS shown in Figure 7 is time-dependent, and the O-P contained in SS N

decreases with time due to PO4-P production by O-P decomposition. PO4-P

production rate decreases with time. PO4 -P production in the fresh deposit

was obtained by the decomposition rate in an incubation test of sediment and

O-P/SS ratio, with the assumption that O-P in test water decreases due to O-P

in SS. Denoting dissolution rate constant as p , the soluble PO -P for 1 day

A is calculated as:

A P - P P x (1 e- p xl (8)

where

P = initial O-P concentration, mg/.

P1 I O-P concentration after I day, mg/.

Dividing A by SS, the PO4-P production rate per 1 mg of SS is obtained.

PO4 -P production rates for 17 samples in seawater and 7 rivers obtained by

this method are plotted to O-P/SS ratio in Figure 8.

108 .

:....-.. . .... ,.>,., ; .. ,.:. .. ,,: , .....- .; . *,, ... ,.....- .. ,.... ... ,.,.. ,. . . . .,.° . . ., . , . - . -, .* ... , ,. *, ...
for whole samples

-1.0 Y-0.066X CX-O 39)

0.

08 ~~ for ~ lower lar=91 =3 -.

c .6 0 Y.0017x(X-0O 16) 0' (r-0.947, n-7)

UE 0a

0~ 0

0.0.2 1 0 upper layer *0 *- lower layer

0 :1 &~-# river

0 2 4 6 8 10

0-P/SS ratio (mg/g)

Figure 8. PO -P production rate from organic substances in seawater .. 4

The linear regression for the lower layer in seawater becomes

Y - 0.017 x (X - 0.016) (9)

Temperature dependence of PO -P production rate is expressed in Figure 9.

*By taking the temperature compensation factor as 1.05, the P0 -P production

* ~rate for fresh deposit T, is expressed as follows: ' .

T - 0.017 x (OP/SS - 0.016) x 1 .0 5 T-25 (10)

* where

OP/SS - 0-P in 1 g of deposit, mg P/g SS

T - temperature, *C

1.0 -- 0 upper (1979)

Y-.76 x1.04

o upper (1980)

a lower (1979)

0.1 - Y.0097xl05-*,

0 W lower (1980)

Y-0039 1.03"-

-rI 9-1.05 I -

00,

0 10 20 30

temperature (*C1

Figure 9. Temperature dependence on PO -P production rate

109
PO04 -P production rate for old sediment T was obtained by a 20-day *1

* incubation test of sediment as follows:

-AC w 1 1(1

At Vd 1w 10

where

AC/At -interstitial PO04-P increase, mg/l/day

TS PO -P production rate per I g of dry sediment, mg/g dry q

sediment/dayt

w -water content

Vd= unit weight g/cm %

The values of T thus obtained by the incubation test at 25*C are

S.

* plotted with 0-P in sediment in Figure 10. -

IQ 0

8 0 0

0

o ~ 0 N.6 o

.2 0

4 04M 050 to5m6ae

0 01 '

0-P (rng/g dry)

The average temperature compensation factor was estimated as 1.06 by

using Figure 11.
0 0-5cmn (r 79

4 O- 1CM MYso)

& 5-I0cmU y BM0~

10'- 0~

A&-

10- A- -

-'0 10 20 30

temperauro MC)

Figure 11. Temperature dependence on PO -P production rate

Accordingly, PO -P production rates for old sediment were expressed for

each layer as: 4

T s 0.0016 x (OP/SS -0.08) x 1.06 T25

(for 0 to 5 cm depth)

T 0.0014 X(OP/SS -0.13) 1.06 t2

(12)

(for 5 to 10 cm. depth)

T 0.00035 x (OP/SS -0.14) x 1.0672

(for more than 10 cm depth)

where

OP/SS - -P in 1 g of sediment, mg/g

T - temperature, *C

Adsorption and Dissolution of Produced P0 4-P

4

matters in sediment was assumed to dissolve into interstitial water and the

rest to adsorp to sediment particles. The increase of interstitial PO04 -P,
* AC*, and the increase of I-P in sediment due to the adsorption AlP were

related with the following equation for the time lapse At and the PO4-P

*.- production rate Tr

tx At AIP + AC* (13)

o.'

where 1

C - interstitial PO4-P, mg/£ "

IP - I-P in sediment, mg/t

interstitial water ratio in sediment, 1/g

t - time, days

By defining allocation factor a between the above-mentioned

interstitial PO4-P, C* , and adsorped I-P

" C*

a =(14)

and substituting Equation 14 into 13,

AlP = x x gt (15)

1+

or

AC* = --- t--16) 1 1+'

1 - x x A (16)

* .is reduced. Vertical distribution of the allocation factor a was obtained

~* in Figure 12.

The variation of a with depth is comparatively large between 0 and

10 cm in depth, and nearly constant deeper than 10 cm. This factor a is

*dependent on temperature and dissolved oxygen. The temperature compensation

factor was selected from the vertical distribution of a at the depth of

80 cm in Figure 12 as follows:

e - (17)

'20

where - -.-

, CL2 allocation factor at the temperature of T°C and 200 C,

respectively.

112 .. x-.

......................................................
0 2 46 810

0" % °

- 1. . .

20 *~

5 

5

40 2 I0/

60 jI;

80

I I0 June DO - 0.6 mg/j 100I1 August D00 1.3 mg/i -

12 February DO 9.1 mg/1

Figure 12. Vertical distribution of allocation factor

By substituting 20 - a2 1.1 ( ) and a 1 1 2 4.92 (g/1), 0 1.02 is

obtained. On the other hand, at 20"C, the allocation factor a of the sediment in Osaka Bay at the depth of 0 to 5 cm is a function of the DO (0 to 2 m

above sea bottom), as shown in Figure 13.

Therefore, a for 0 to 5 cm is expressed with the aid of Equation 17 as

DO T-20 (8 a - 11.5 x 0.748 x 1.02 (18)

The a for more than 5 cm in depth is a constant value of 6.1 g/l based

on the results of Figure 12. The a in surface layer thus varies with

temperature and DO, and the following relation must be held in order to

satisfy the equilibrium due to the increase of adsorption Q -.-. "

a (19) IP + Q

or

a IP

1 + a - (20) ....

-:5..:-.:.:

where

Q - adsorption of I-P, mg/L.

113
100

Y- 11.5 xO.748 X

(r- 0.727, n-62)

0 a sampled at off -Nishinomia

% a sampled in 1980 10 o sampled in 1981

-0 n94 O 3boratory test

A 00 0

00 Oo OA"." 00o

0 000 !

000C')

0.1+

0 I 2 3 4 5 6 7 8 9 10

DO (mg/) sediment of the depth 0 to 5cm

DO at 0.2 to 2m deep above sediment

temperature 200C

Figure 13. Allocation factor and DO

The time required to attain equilibrium d for Equation 20 is approximately 20 hours (6). Thus, d was taken as 1 day and adsorption rate q was

expressed as:

1 - - IP

q = x Q , a (21)

where

q = adsorption rate, mg/g/day

d = time required for equilibrium adsorption rate, days

Movement of Substance in Sediment

O-P movement

O-P in accumulated SS gradually decreases with time within the sediment.

For the disturbed lower layer, deposit AS , O-P in sediment, P , SS S

n n n

and PO4 -P production rate T after the n-th day were estimated as illus4 n trated in Figure 14 and Equation 22.

11

. - ...........
Stempe rat ure T, Tv T& i dep o s t deposits depos.t

S,.,', 0 "", 

.

first day second day third day

P stock P, OPx AS, Ps P%-rISX*OPXAS, P&fP%-rKSI*OPx&Ss

SS stock S . SSS, *AS.S, -= AS, ,..+.-. P production rate r. fCP,/S 1.T,} r, f(ps/Ss.Ts] r,=f(PS/SI.T&) -.

T temperature

OP:O-P in deposits

Figure 14. Estimation of SS, P, and produced PO4-P

P P - T X S + OP x AS

n n-i n- I n-i n

Sn = n I + AS (22)

T= f(Pn/S ,T n n n'

where

OP -O-P in deposits .X

T - temperature

Dispersion and release

Dispersion of interstitial PO4 P between layers was expressed as a

general form of the function of vertical concentration gradient as shown in

Equations 3 and 4. PO -P release rate R was expressed as the dispersion 4 from sediment surface to seawater as follows:

-* C

R- ' x D x 1 w (23) H /2

where

2 R = PO4 -P release rate, mg/m /day

*' .void ratio

2

D = dispersion coefficient, m /day

115 • P.s
-- 7 74L 1 "-

C* - interstitial PO -P in the first layer, mg/L 4

Cw - PO4-P just over the sediment surface, mg/t '

H = thickness of the first layer, m

To the samples of the 0- to 30-cm layer, the 50- to 80-cm layer, and the

100- to 130-cm layer, laboratory test results were obtained as shown in

Figure 15.

60

-2 4 0 0 0 0 - 3 0 ¢ ,, :0

40 0 50-80cm :a

200 hZ002

0V0 0 9 11C

0 0 A S-.6

oCO o -- t x- o ""

00

0 50 100 150x 10,

*x(C* -C. x10

0. SHi"

Figure 15. Dispersion coefficient

Assuming that the temperature compensation factor of the dispersion

coefficient is equivalent to that of molecular dispersion coefficient of

cation or anion, 1.03 T the dispersion coefficient at arbitrary temperature

-D DT is expressed by i'

-4 T-25 (4

D = 1.41 x 10 x 1.03 (24) .. ' .%*

Agitation -

.'.'.:,

As stated before, the upper four sediment layers were treated as an ,.,

agitation layer. The agitation coefficient DSL was expressed as

T DSL xC X- (25) SS

where "*. -

22

T = SS flux, g SS/m2/day

DSL - agitation coefficient, g SS/m 2

L - displacement of sediment, m

116

,----....-

. . .. .. . ..... ... .... ... .. . . . . ... . . .<. .,. . . . ,. _,_.._._ ., ... .. _.. .- _.,.,, ,_
- - rrrr-r-wv-c---,.wr-w..r1 -7-7~Wr. -, rr ~ -t1- ~ .1 ~ . ~ --

By regarding the physical property of sediment less than 15 cm in depth .

as homogeneous and assuming SS in one half of the agitation layer (i.e.,

7.5 cm moves a distance of 15 cm for 4 years), then sediment in the layer is

completely mixed. Thus, DSL was estimated by Equation 25 as

DSL - 3.4 x 0 (m /day) (26)

Water Ratio and Unit Weight of Sediment

The vertical distribution of water ratio w and the unit weight Vd ofP

*sediment at off-Nishinomia was obtained as shown in Figures 16 and 17.

water Content

00 0.2 0.4 0.6 0.8 1.0

I0

20-

E .~30

V: 40

50

60}

Figure 16. Vertical distribution of water content

unit weight (g/Cm'")

09 1.0 IA [.2 1.3 1.4 0

10

20 1.03t0.g6axZO-060

E30

S40

60 '%

Figure 17. Vertical distribution of unit weight

117

.
_6" "'K._17; 

g/c 3 Jb%

Assuming that w = 1.0 and Vd - 1.03 g/cm at the sediment surface

(z = 0), and that w and Vd vary exponentially with depth z the

following relations are obtained:

0.0689 """ w I-0.268 x z ...-

(27)

P VERIFCATION 0F0MODE

Vd 1.03 + 0.168 x z0 80 ..-. e

Computational Conditions

For the verification of the model, the O-P settling rate and DO in bottom

water were presumed to be the term of the past 100 years. The settling rate ""

p of phosphorus was assumed to be proportional to the phosphorus in seawater.

Long-term variation of phosphorus was decided on the basis of data observed by

Kobe Marine Observatory in 1934-35, 1952-53, and 1974-79, and by the data

obtained by prefectural governments after 1976. This result is shown in

Figure 18.

Furthermore, the annual variation of O-P in the lower layer was assumed

by the simulation results from the two-layer nutrient-cycle model (1). DO was

also calculated at almost the same period as O-P. DO in lower layer was,

therefore, given as

DO =DO1 -(DO- D02) x 0 (28)

where

DO1 - DO at salinity 31.6 ppt and given temperature

D02 - observed DO (see Figure 19)

8 - unsaturation index to a standard year

8 was determined from the records shown in Figure 20. Temperature

variation was periodically given as shown by the line in Figure 21.

019

0

MO 151Ea 15"

UN 1

"E10--

(L 63

0 08

z 1880 1900 1920 1940 1960 1980

Year .

Figure !8. Long-term variation of phosphorus accumulation

118

-,v - ...- ,. : -.: . . '.. . ..3 --. ''' .......... -- % ..- v .-:. -.- .,... -- , . .-.,, .4. .:. .. -. , . .. .. , .
I-* -7-- ' 7-7 IF zu T. V%" q -CT 9_."M .T. W . .

' 1.. 7. -L12o- 0 • observed

0

oa ! I I I I I I

I 2 3 4 8 6 7 8 9 10 i 12

month

Figure 19. Observed DO and saturated DO

1.0 1.0ro "°0.79

0.6-

0.4 0 -"'

S0.2- 009 0 0 - I I I I I = :. I I I . I I I 1880 1900 1920 194C 1960 1980

year

Figure 20. Long-term variation of DO reducing factor

Calculated Release Rate and Vertical Distribution of Phosphorus

A numerical simulation of Equations 1-5 was conducted for the 100-y'ear

period from 1880 to 1983 by applying the above conditions and a time increment

At = 0.1 day. The calculated annual variation of release rate is shown in

Figure 22 for the most recent year of 1983. The calculated release rate is

slightly greater than the observed value, but annual variation generally

coincides with the observed one. The release rate integrated with the time

range of each year is shown in Figure 23. PO4 -P release has a close relation

with settling load of O-P as shown in Figure 18, and rapidly increases after

1950. The observed annual release from 1979 to 1981 is in the range of 3 to

2

4 g P/r /year, and calculated value also lies on this range.

The vertical distribution of calculated T-P, O-P, I-P in sediment, and

interstitial PO4 -P is shown with observed values in Figure 24. According to

these results, vertical distribution of calculated phosphorus in the lower

layers (from first to fourth) coincides closely with the observed value, with

the exception of interstitial PO4-P. Calculated phosphorus lower than the

fifth layer is about half the observed value, and seems to be very sensitive

to initial values, iteration time, and other parameters.

119

........................ .. .. . . .. ,., +. . .

............... _ .. ,.... .........
30 -

14~~

30

E ~ V_ ~ ~ 2 bere

00-

1 4 6 7 8 0 1 1

300

0. obseroserve

(att off- Nishinomia)

0

1 2 3 4 5 6 7 8 9 10 It 12

Figure 21. Seasonal variation of emeerate

302
.o >

II o 

@5

E.. 4

-3

0

1880 1900 1920 1940 1960 1980 i _

yeor .

Figure 23. Long-term variation of release rate .. 4 "

NUMERICAL PREDICTION ON THE EFFECT OF RELEASE CONTROL DUE TO DREDGING

Dredging and Layer Partition

Assuming a surface dredging thickness of 50 cm, layer partitioning before

and after dredging was executed as shown in Figure 25. By dredging, the

layers from the first to fifth predredging were removed, and the sixth and

seventh predredging layers corresponded to the first to fifth layers after

dredging.

Treatment of O-P Load and DO After Dredging

The O-P load to sediment decreases after dredging due to improved

seawater. The O-P just over the bottom is decided by both inflowing load and

internal production, and these relations are rather complicated. Owing to

this fact, O-P and DO were decided on the basis of simulation result of Osaka

Bay, i.e., natural condition, release cutoff condition, and release and

inflowing load cutoff condition. Calculated O-P values at off-Nishinomia are

listed in Table 1.

TABLE 1. O-P IN LOWER LAYER CALCULATED BY THE TWO-LAYER MODEL

Condition O-P, mg/,

Natural 0.027

Release cutoff 0.016

Both release and effluent cutoff 0.009

121

.-. . '.2. .. .

!::o~ ~~~~~~~~~.................,........ ...... .... . .... .. ,..,.... .!:
L°b

T-P ling/g) O-P (ing/g)

0 02 04 06 08 1.0 0 02 04 06 08 1.0

E 50 50

10 100 C, oo

"50" 150

~~:00

E 50 50

aAiersust 8

-P (g/g] P0-P (mg/I)

F 24 u 0e 0 .0 obsed in02 1981i. P6 

122 22

E 50 150sa

- • = - * .

- ;. ;2 2"2

* ,-.'

' 100 /.

00*%

oser.d u..1-8 ..- ..'-"'. August 1981 ~

" "ca'c'l

24 TP 0Pgad"-Pi sdiet nditesttalP0-

.• , .., ., ,.. ,..., .. ... .. .., ._:' ., .: .,. . .., ., ., ..., .., ... ,.. .
(cm)

0 st

4th

25 dredging

(Jan. I st 1975) b

5th

50 ......... 0 4 lit..-'-.

S- 5 2nd

6th , -3rd

75------------ 22 

71h -5th *.-1

oo .. 6th

Figure 25. Layer correspondence before and after dredging

The O-P from the natural condition to the release cutoff condition was

estimated as the basis of release and effluent cutoff condition as ...

(0.016 - 0.009)/(0.027 - 0.009) - 0.388

Therefore, supposing O-P - 1 and R - 1 in the natural condition, then

the relationship between O-P and R is expressed by linear interpolation as

* Figure 26.

Settling R = 1 for before dredging and R - R at a specific time after

dredging, then the reducing factor of O-P load to natural condition 8 is

" expressed as

0.612 R + 0.388 (29)

In the same manner, DO after dredging was estimated by using above B

as:

DO after dredging - natural DO + saturated DO x (1 - B) (30)

123

.7-C

* . . . . . . . . . . . ..
-1.

o 0.0 R 0 .

rees0ai onaua odto

Afte the omptatinfr50easersti tatrtin wonitntrlcniino

0-P, I-P in sediment, and interstitial PO -P, another 50 years of computation

* after dredging was continued. The variation of P04-P release is shown in

Figure 27.

*6 40r

.~30-

; 20r

35 ou 40 45 150 25 3

Figure 27. fte reesd utfgfecinnisdrtingm

1240.

*. . . . . . . . . . . . . . . . . . . . . . . . . . .

. .. . . . . . . . 20 . . ..
Comparing each peak value during each summer found a release cutoff ratio

of 702 Just after dredging, 50Z after 20 years, and 202 after 50 years. Such

a gradual reduction of the effect seems to depend on newly accumulated

substances. The above results are, however, deduced on the basis of many

uncertain parameters and assumptions. Further investigation is necessary

until a satisfactory solution is obtained.

CONCLUSIONS

A numerical model was developed to predict the behavior of phosphorus in

sediment. For verification of the model, O-P, I-P in sediment, interstitial

PO 4 -P, and PO4 -P release rates were simulated from the data of the past

100 years. Furthermore, the release cutoff effect and its durability due to

dredging were investigated by this model.

These results are summarized as follows:

a. The model's variation of PO -P release rate and integrated release 4

rate over the year are closely correlated with the observed values.

b. The vertical distribution of T-P, O-P, and I-P in sediment closely

matched the upper layer, but the lower layer was underestimated

because of the effect of initial condition, iteration time, etc.

Interstitial PO4 -P was overestimated to the upper layer.

c. Release cutoff was very effective just after dredging, but reduced

with time. Further investigation is necessary to obtain a

satisfactory solution.

ACKNOWLEDGEMENTS

This investigation was financially supported by the Third Port "-

Construction Bureau and Environmental Protection Division, Bureau of Port and

Harbor, Ministry of Transport. A part of this result has been presented by

the author and Y. Hosokawa, former Senior Research Engineer of Port and Harbor

Research Institute (2). Most of the field data applied here were obtained by

the Third Port Construction Bureau.

I must express my thanks to Prof. H. Nakanishi of Yamaguchi University,

Prof. T. Horiguchi of Tokyo Metropolitan University, Assistant Prof. T. Morioka

of Osaka University, and Assistant Prof. M. Ukita who gave a lot of instructions on the fulfillment of this investigation.

REFERENCES

1. Horle, T., and Hosokawa Y. 1983. "Water-Quality Controlling Factors in

an Eutrophication Model," Report of Port and Harbor Research Institute,

Vol 22, No. 3, pp 159-205.

2. . 1984. "Modelling of the Behaviors of Phosphorus in Sea Mud,"

Report of Port and Harbor Research Institute, Vol 23, No. 2, pp 49-74.

125

. .... *
3. Kadokai, S., and Noriki S. 1983. "Oceanographical Chemistry (J)," Sangyo

Tosyo Pub. Ins., 185 pp.

*4. Kikuchi, T. 1981. "Benthos Activity with Special Reference to Bioturbation, Bulletin on Coastal Oceanography, Vol 18, No. 2, pp 67-77. '~r

5. Matsumoto, E., and Yokota, S. 1978. "Accumulation Rate and Heavy Metal

Pollution in Osaka Bay Sediments (J)," Journal of Oceanographical Society

of Japan, Vol 34, No. 3, pp 108-115.

6. Shimokava, K., et al. 1981. "Adsorption of Inorganic Phosphorus by River

Sediment (J)," Japan Journal of Water Pollution Research, Vol 4, No. 1,

pp 31-36.

126
ECOLOGICAL EVALUATION OF ORGANOTIN-CONTAMINATED SEDIMENT

M. H. Salazar and S. M. Salazar

Environmental Sciences Division

Naval Ocean Systems Center

San Diego, California 92152

ABSTRACT 4,-

r .

A standard dredged material bioassay was

conducted on sediment with high levels of organotins

to (1) assess the toxicity and bioavailability of

organotins associated with sediment, and (2) determine

if this sediment would qualify for ocean disposal.

Since the Navy is considering fleetwide implementation

of organotin coatings and some commercial fleets are

currently using them, it is essential to evaluate the

effects of organotins on the dredging permit process.

Particulate-phase tests were conducted with

Acanthomysis sculpta (mysid), Citharichthys 8tigmaeus

(flatfish), and Acartia tonsa (copepod). Solid-phase

tests were conducted with A. sculpta, Macoma nasuta

(clam), and Neanthes arenaceodentata (polychaete

worm). The bioassay also included an estimate of the

potential for bioaccumulation of cadmium, chromium,

copper, mercury, silver, pesticides, PCBs, petroleum

hydrocarbons, and organotins.

The concentration of tributyltin-oxide in sediment collected from Commercial Basin was measured to

be 780 ppb. Initial concentrations of TBTO in particulate phase test water was 0.49 ppb and in solid

phase test water 0.20 ppb. Butyltins measured in test

water and test sediments demonstrate that monobutyl-,

dibutyl-, and tributyltin were all leached off Commercial Basin sediment. Treatment clams accumulated

organotins to a concentration an order of magnitude

above control clams (2.82 ppm TBTO vs. 0.26 ppm TBTO)

and a factor of four above treatment sediment.

Survival was high in all particulate phase and

solid phase tests. There were no statistically signiftcant differences in survival when controls were compared to treatments. As demonstrated for other contaminants in other studies, high levels of organotins

in sediments do not a priori indicate a significant

adverse impact on the marine environment after ocean

1.27

:A. .. . . .'.. .

-. ~.2 **~ 4.2~' 5 2* .*. U .-7 t !ta. * t .- - . . 42 4 A*..A . . ?
,.,.

disposal. The sediment tested would qualify for ocean

disposal under the present guidelines administered by

EPA and the Army Corps of Engineers.

INTRODUCTION

Commercial Basin, San Diego Bay, California, is an area that is heavily

used by both commercial and private vessels. These vessels are coated with

antifouling paints that leach copper or organotins into the water column. A

significant portion of these contaminants are adsorbed by the sediment. Previous measurements in the area have shown elevated copper levels in the water

column, presumably from the antifouling coatings (11, 33). More recent analyses performed by this laboratory indicate the Commercial Basin water column to

have the highest levels of tributyltins as tributylin-oxide (TBTO) found in

San Diego Bay (30). TBTO concentrations for water collected near the bottom --

ranged from 0.11 to 0.55 ppb. These water column values are close to those

causing effects on sensitive marine organisms like mysids and copepods in laboratory tests (20, 27, 29). Corresponding sediment samples from the same area

ranged from 32 to 560 ppb TBTO. This represents a concentration factor of

approximately three orders of magnitude between the water column and the

sediment.

It is estimated that more than 20 percent of the vessels in Commercial

Basin currently use organotin-based antifoulant coatings. The environmental

impact of organotins from these coatings is of great concern to the Navy due

to projected Fleet implementation of organotin-based antifouling coatings. As

part of a research program on the fate and effects of organotins in the marine

environment and a program to expedite Navy dredging, we performed a bioassay

on sediments collected from Commercial Basin. This site was selected, even

though it is not a Naval facility, because of the high concentration of TBTO

found there. The purpose of this work was to (1) assess the toxicity and

bioavailability of organotins associated with sediments, and (2) determine if

sediment with these high organotin loads would qualify for ocean disposal

under the present guidelines.

According to Section 103 of the Marine Protection, Research and Sanctuaries Act of 1972, sediments to be dumped into ocean waters must be evaluated

to determine the potential environmental impact. Evaluations must be in

accordance with criteria in the Federal Register, Vol 42, No. 7, Tuesday 11

January 1977. Previously, evaluations were based only on chemical analyses of

dredged material. Now, sediment chemical analyses are not required and bioassays are the primary basis for determining the potential for environmental

impact. The intent of the law is to prevent an adverse environmental impact

from ocean disposal of dredged material.

The standard bioassay test procedures have been published by the Environmental Protection Agency (EPA) and the Corps of Engineers (COE) in an Implementation Manual (6). We conducted an ecological evaluation of Commercial

Basin sediment according to the bioassay procedures outlined in this manual

128

F .
even though no dredging or ocean disposal is planned for this sediment. The

following are the results of the evaluation performed on sediment from Commer- V

cial Basin, San Diego.

METHODS

The procedures given in the manual for the "Ecological Evaluation of

Proposed Discharge of Dredged Material into Ocean Waters" (6) were followed

wherever possible and practicable for the majority of the bioassay. It should

be remembered that the Implementation Manual was intended to be only a guide

and need not be followed exactly. In 1983 the COE, Los Angeles District, also

outlined requirements and guidance in "District Bioassay Testing Procedures."

These regionally specific procedures were also followed wherever feasible.

The most significant procedural modification used in these bioassays was a

conceptual one. Instead of collecting sediment from three sites within each

dredging area and conducting three bioassays per site as the manual suggests,

we collected sediment from three different sites in the dredging area and

pooled them for one bioassay. Sediment samples were pooled by mixing during

collection, preparation of particulate phase slurries, and pre-sieving for the

solid phase.

Although the manual suggests using 10, 50, and 100 percent test solutions

of liquid and particulate phases, for this bioassay we used only the

100 percent particulate phase solutions for two reasons. First, the suspended

particulate phase incorporates both a liquid and a particulate phase. Second,

in all our previous bioassays we have not had a significant effect with the

100 percent particulate phase solutions. Therefore, the lesser dilutions (10

and 50 percent) are superfluous. For these reasons, only 100 percent suspended particulate phase solutions were prepared and tested. To increase

statistical reliability we used five replicates instead of the recommended

three. These changes were also made with agreement of EPA and the COE.

Sediment

Collection Procedures

Three samples were collected along a pier on the northwest shore in Commercial Basin (Figure 1). Test sediment was collected from the upper 20-30 cm

of bottom material by SCUBA divers using plastic buckets. On the surface the

sediment was dumped into 60-liter ice chests which were lined with large plastic bags to reduce potential contamination. Ice chests were used for ease in

handling sediment and to maintain the temperature of sediment between collection and storage. The sediment was stored at 4*C and used 48 hours after

collection. Approximately 200 liters of reference/control and 100 liters of

treatment sediment were collected.

Sediment Characteristics

Sediment that would serve as oth a reference and a control was collected

in an uncontaminated area off North Island near the mouth of the bay

(Figure 1). Sediment from this area has been used as a combined reference/

control in our 19 previous dredged material bioassays on San Diego Bay sediment. It can be used as a reference because mean grain size and composition

are similar to disposal site sediment. Available information suggests that

129

'a".. °.
COMMERC

BASI

NORTH

ISLAND

CONTROL

SITE . . SEAWATE* INThAE *

COMMERCIAL

BASIN

SNELTEN ACOLLECT l.

ISLAND WIES

Figure I Location of Commercial Basin and control

sediment collection sites in San Diego

Bay, and the seawater intake.

the average grain size at the nearest interim EPA disposal site (LA-5) is between 0.030 mm (4) and 0.079 mm (12). The mean grain size of the control ...

sediment used in these bioassays was 0.0981 mm. Control sediment was composed

of approximately 81 percent sand and 19 percent silt and clay, and is classified as fine sand (31). This is similar to disposal site sediment composition

estimated at 67 percent sand and 33 percent silt and clay (12). Grain sizes

for control and treatment sediment were measured by the tube drop method.

This sediment can also serve as a control because of its relatively low

contamination. As part of our previous bioassays we measured five heavy

metals (Cd, Cr, Cu, Hg, Ag), petroleum hydrocarbons, PCBs, and pesticides in

test sediment. Control sediment has almost always been significantly lower in

these contaminants than treatment sediment (21-26). In many cases contamination was lower by approximately an order of magnitude. Relatively low contamination combined with sediment composition and grain size, which are similar

to disposal site sediment, Justify using North Island sediment as a control.

For expediency this reference/control sediment will be referred to as "control

sediment."

Seawater

The manual suggests that disposal site water be used if possible. This

was impractical because of the large volume requir~a and the distance to the

sit,. Nearshore seawater available at the Naval Ocean Systems Center (NOSC)

Marine Life Sciences laboratory was used for this bioassay. The seawater

130

.P ."~~. - *.*-*. - *-'-* .-. i.p7.,*** . **. *L ~ .. - -
". intake for this system is approximately 250 meters from shore (Figure 1).

. This natural seawater was passed through large sand filters prior to delivery

". in the laboratory.

Periodic water analyses have shown that the five heavy metals (Cd, Cr,

Cu, Hg, Ag) we routinely measure to assess bioaccumulation are present in only

trace amounts. These concentrations are similar to those found in open-ocean CA

4, water (2). Analyses of tissues from test animals in previous bioassays have

shown no significant accumulation of heavy metals, hydrocarbons, PCBs, or

pesticides (21-26).

Preparation of Test Tanks

Suspended Particulate Phase

Test slurries were prepared in a 4:1 ratio as the manual recommends by

adding 120 liters of control water to 30 liters of treatment sediment. Clean,

aged 50-gallon plastic trash cans were used for mixing. The slurries were

* mixed by vigorous bubbling with compressed air at a rate of 50 liters per

minute. After 30 minutes of bubbling, the air stones were removed and the

slurries were allowed to settle for one hour. After settling, the supernatant

was pumped directly into test tanks for the 100 percent suspended particulate

phase test.

Solid Phase

Treatment and control sediments were sieved through 1.0-mm stainless

steel screen to remove endemic organisms. Solid phase test tanks were pre-

* pared with a 15-mm layer of treatment sediment on top of a 30-mm layer of

control sediment. Control tanks for the solid phase tests were filled with

control sediment to a depth of 45 mm. After distribution of the sediments,

the tanks were slowly filled with control water. Animals were added after

preparation of the solid phase tanks.

Test Animals

Suspended Particulate Phase

For the particulate phase the manual suggests using phytoplankton or

zooplankton, a crustacean or mollusk, and a fish. A copepod (planktonic

cruotacean), a mysid (hypoplanktonic crustacean), and a fish were used in this

phase of the sediment bioassays. The manual further suggests that organisms

from the disposal site be used where possible. It was not practicable to use

species collected from the disposal site because they are neither well known

nor easily obtained.

Acartia tonea, a copepod, was selected to satisfy the zooplankton

requirement in the particulate phase. Acanthomysis scuipta was used as the

representative crustacean species. The speckled sanddab, Citharichthys

SStqraezq, was the third species used for the particulate phase tests. All C.

-.'. stigmaeus surviving at the end of the 96-hour test were weighed and measured. ..

These animals had a mean length of 62.8 mm and a mean wet weight of 2.75 g.

131

...... - -..'.".........IL...}' "...."". ..* .. ''""' '
2-46 'R V i.- TI-TV r V T.- i.. ig.o_.°

Solid Phase

The manual suggests using three species for solid phase tests, one

filter-feeder, one deposit-feeder, and one burrowing species. It is further

suggested that the species be selected to include a cruitacean, an infaunal

bivalve, and an infaunal polychaete. As with the particulate phase, it was

not practicable to use species from the disposal site. Solid phase tests for

the Commercial Basin bioassay were conducted with A. scuZpta (mysids),

Neanthes arenaceodentata (polychaete worms), and Macoma nasuta (clams).

Estimates of lengths and weights for clams were made by measuring and

weighing 50 animals per treatment at the end of the bioassay. Test animals

had a mean length of 40.6 mm and a mean wet weight of 8.24 g.

Bioaccumulation

The manual suggests that all biological evaluations of the dredged material include an assessment of the potential for contaminants to be bioaccumulated in the tissues of marine organisms. We used M. nasuta as one bioaccumulator because of the relatively large amount of tissue available for chemical

analysis. We used N. arenaceodentata as the second required bioaccumulator.

Animal Collection

We collected copepods and mysids just outside the mouth of San Diego Bay

on the first day of the test. Copepods were collected by slowly towing a net "

(175-u mesh) in open water just beneath the surface. Mysids were collected in *

the surface canopy of the kelp with buckets. Temperature upon arrival was

18C for both species.

Three of the five species of marine organisms used in these bioassays

were purchased from two commercial suppliers. Fish and clams were collected

by Brezina and Associates, Dillon Beach, California. The fish were collected

near the mouth of Tomales Bay, California, in 10-15 feet of water. The clams

were collected in an intertidal mudflat, also in Tomales Bay.

N. arenaceodentata is kept in continuous culture by Dr. Donald Reish,

California State University, Long Beach. They were obtained one day prior to

the start of the test.

Test Conditions

Polycarbonate tanks, which exhibit low adsorption of trace metals and

organotins, were used as test containers in the particulate phase and solid

phase tests for all species except copepods. We used Pyrex beakers for

copepeds because Pyrex glass is also nonadsorptive and the size is convenient.

Temperature at the 600-foot-deep disposal site probably ranges between 8

and 10'C. We used water temperatures between 13.5 and 16,CC for this bioassay because they are closer to the optimum for maintaining these particular

test animals and because of the limits of ocean temperature and the ilowthrough seawater system. Physical-chemical parameters were measured daily.

Cool white fluorescent bulbs were used to approximate the spectral output of

the sun, but irradiance In the test ccntainers was significantly less than the

132

..............."°•2#".-"-. .- - *. •.. ...... .... . . . . - ..- -
- - - - . - - . . - - . -, •-'. 

1200 microwatts/cm2 recommended by the manual. Irradiance was measured with a

photometer. For each test species the values obtained (microwatts/cm2 ) were

as follows: C. 8ti 9maeu8 (100-500); N. arenaceodentata (1-250); A. sculpta

(1-250); M. nasuta (100-250); and A. tonsa (5-50). The light regime consisted

of a 14L:1OD cycle.

Suspended Particulate Phase

The copepods were held in 400-ml Pyrex beakers, mysids in 4-liter polycarbonate tanks, and fish in 16-liter polycarbonate tanks. All particulate

phase tests were conducted under static conditions for 96 hours. Five replicates were used for each treatment and control condition with 10 organisms in

each replicate. The fish were vigorously aerated at a rate between 500 and

1300 ml/minute. Mysids were moderately aerated at a rate of 3-7 ml/minute.

Copepods were not aerated.

Copepods were fed maintenance levels of the, phytoplankton Isochrysis

galbana. Feeding occurred on days 1, 2, and 3 of the bioassay (1,000-10,000

cells/copepod/day). Mysids were fed maintenance levels of brine shrimp

nauplii (25-30 nauplii/mysid/day). The fish were not fed during the bioassay.

Live animals were counted at the end of each test. It was impractical to

count live copepods and mysids every day as suggested in the manual since the

* only reliable method involves removing the animals. This procedure would

severely stress the delicate test organisms and could adversely affect the

results. Fish were counted daily and dead animals removed. During the

* particulate phase tests seawater temperature was maintained at 13.5-15.3C,

salinity between 31.0-33.0 ppt, dissolved oxygen between 6.0 and 8.0 ppm, and

pH between 7.4 and 7.8 for all species tested.

Solid Phase

The solid phase tests were run for 10 and 20 days. The 10-day tests

utilized A. sculpta only. The mysids were maintained in 4-liter polycarbonate

tanks under static conditions. Five replicates were prepared for each treatment and control condition with 20 organisms in each replicate. As in the

particulate phase tests, mysids were gently aerated (3-7 ml/minute) and fed

brine shrimp nauplii daily (25-30 nauplii/mysid/day).

Clams (M. nasuta) and worms (N. arenaceodentata) were held in test sediment for 20 days using flow-through seawater. These organisms fulfilled

requirements for both the 20-day survival portion and the bioaccumulation portion of the bioassay. Clams and worms were maintained in separate 16-liter

polycarbonate tanks. Five replicates were prepared for each treatment and

control condition with 20 clams per replicate and 25 worms per replicate.

Clams were not fed. Worms were fed TetraMin SM80 fish food on days 4, 7, 11,

14, and 18. Fish food flakes were ground with a mortar and pestle and combined with seawater to create a slurry that was injected into the water with a

large syringe. Each tank received 125 mg of food (5.0 mg/worm) on feeding

days. The number of live animals was determined at the end of the test

instead of during the test as the manual recommends, because counting during

the test disturbs the sediment regime and places additional stress on test

animals.

133

-" .
Seawater was delivered to these tanks using a manifold system developed

as part of the Navy program to evaluate the toxicity of organotin antifouling

compounds (13). Flow rates were approximately 170 ml/minute. All tanks were

aerated at a rate between 500 and 1000 ml/mlnute. For these animals seawater

temperature was maintained between 14.0-16.3'C, salinity between 31.0-

34.0 ppt, dissolved oxygen between 6.2-8.3 ppm, and pH between 7.6-8.0.

Bioaccumulation

At the end of the bioassay, test sediment was removed by wet-sieving.

Clams and worms were counted and immediately returned to their original

flow-through test containers. The clams and worms were then fed rations of...-

TetraMin; worms were fed 5.0 mg each and clams 14.0 mg each. These animals

were held for a 24-hour depuration period. The animals were fed to encourage

elimination of ingested sediment. After the 24-hour depuration period, the

animals were removed and tissues frozen for subsequent bioaccumulation

estimates.

Tissue and sediment samples were analyzed for cadmium, chromium, copper,

mercury, silver, pesticides, PCBs, petroleum hydrocarbons, and organotins.

Cadmium, chromium, copper, and silver were analyzed by graphite furnace

atomic absorption spectroscopy; mercury by cold vapor atomic absorption

spectroscopy. Pesticides, PCBs, and petroleum hydrocarbons were measured by

gas chromatography. The manual does not require chemical analysis of

sediment. It was analyzed here to document the amount of contaminants

available for bioaccumulation in control and treatment sediments and to

provide confirmation of control sediment selection. Analytical measurements

were conducted by Anatech Laboratories, Santa Rosa, California.

All organotin measurements were made by NOSC personnel. To determine the

amount of organotin released from sediment upon mixing, seawater samples were

taken from the suspended particulate phase preparation container just before

adding the test slurry to treatment tanks. Solid phase water samples were" -

taken from mysid tanks on the first and last days of the bioassay. Butyltin

species were measured in these and control water samples using a hydride

reduction method followed by hydrogen flame atomic absorption

spectroscopy (30).

The total tin concentration in test sediments was measured at the beginning and end of the bioassay. Bulk samples from the collection chests (Control and Commercial Basin) and test samples from solid-phase mysid and clam

tanks were taken on the first day of the bioassay. Samples were also taken

from solid-phase control, mysid, worm and clam tanks on the last day of the

test. The concentration of total solvent-extractable tin was measured by

graphite furnace atomic absorption spectroscopy (27).

Additional clams from the 20-day bioaccumulation study were used to

determine organotin uptake. Accumulated organotins were extracted from ground

clam tissues with methylene chloride. Samples were placed on a rotary shaker

for 24 hours to ensure complete extraction. The concentration of total .- .* *

solvent-extractable organotin was determined by graphite furnace atomic

absorption spectroscopy. The tin values expressed as W Sn/g dry tissue were

134

. -.... .q-- . t. . . . .-. a~ t a- 
multiplied by 2.5 to estimate TBTO concentration and then multiplied by 0.20 * -. . , to estimate a wet-weight concentration comparable to our other bioaccumulation

data.

Data Analysis Procedures

Statistical methods outlined in the manual were followed wherever possible. Homogeneity of variances in bioaccumulation data was assessed with the

Max-F test. Significant differences were assessed by either the Student's

t-test if the variances were homogeneous, or the Mann-Whitney U-test if they

were not.

Survival data for control and treatment organisms in the particulate and

solid phase tests are discrete data. Therefore, instead of the t-test as

recommended by the manual, we used its nonparametric equivalent, the MannWhitney U-test (3, 32) to compare treatment and control survival. Significant

results for all statistical tests were determined by the critical values

(a - 0.05) of the appropriate distributions.

RESULTS

The Commercial Basin bioassay was conducted in March 1984. Percent

survival for the particulate phase and solid phase tests is presented in

Tables I and 2. Results of the statistical analyses are presented in Table 3.

No statistically significant differences in survival were found between controls and treatments for any of the species tested. The concentrations of

contaminants measured in test animal tissues and in test sediments are presented in Table 4. The mean concentration and the results of statistical

analyses on these data are included in Table 5. No statistically significant

differences in bioaccumulation were found between control and treatment groups

except for copper, PCBs, and organotins in A. nasuta and copper and silver in

N. arenaceodentata. The concentrations of organotins in test sediments, test

water, and clam tissues are given in Table 6.

Suspended Particulate Phase

In particulate phase tests (Table 1) with fish, control survival was

98 percent and treatment survival was 96 percent. Control and treatment

survival for mysids was 100 percent. For copepods, control survival was

88 percent and treatment survival was 82 percent. There were no statistically

significant differences in survival between control groups and the Commercial

Basin treatment groups for any of the animals tested.

Solid Phase - 10-Day Tests

In 10-day solid phase tests with mysids, control survival was 95 percent

and treatment survival was 86 percent. There was no statistically significant

difference in survival between controls and treatments.

Solid Phase - 20-Day Tests

In 20-day solid phase tests (Table 2) with clams, both control and treatment survival was 99 percent. In 20-day solid phase tests with worms, control

135

A -. . . . ... . . ..... . . .*-.**,.... .s..,-... 
TABLE 1. THE NUMBER OF FISH (CI2WARICFT9YS STITGAAEVS), MYSIDS

(ACANTIHOMYSIS SCULPTA), AND COP EPODS (ACARTIA TONSA)

SURVIVING AFTER 96 HOURS OF EXPOSURE TO 100 PERCENT

PARTICULATE PHASE MATERIAL

Replicate u-..

Species Number Control Commercial Basin

Citharichthys stignaeue 1 9 10

2 10 10

3 10 10

4 10 8

5 10 10

98% 96%

Acanthomysis scuipta 1 10 10

2 10 10

3 10 10

4 10 10

5 10 10

10% 00

Acartia tonsa 1 6 8

2 8 82

3 108

4 10 8

5 10 9

88% 82%

136
.%

TABLE 2. THE NUMBER OF MYSIDS CACANTHOMYSIS SCULPTA), WORMS

(NEANTHES ARENACEODENTATA), AND CLAMS (MA COMA NASUTA)

SURVIVING THE SOLID PHASE TESTS. MYSIDS WERE EXPOSED __

FOR 10 DAYS; CLAMS AND WORMS FOR 20 DAYS

Replicate

Species Number Control Commercial Basin *

Acanthomysis scuipta 1 18 16

(10-day test) 2 17 19

3 20 17 '..

4 20 19

5 20 15

*Necinthes arenaceodentata 1 23 20

*(20-day test) 2 25 21

3 24 20

4 15 23

5 19 25

84.8% 87.2%

Macoma nasuta 1 20 19

(20-day test) 2 20 20

3 20 20

4 20 20

5 19 20

137
TABLE 3. STATISTICAL VALUES FOR DETERMINING SIGNIFICANT

MORTALITY IN 100 PERCENT PARTICULATE AND SOLID *.

PHASE TESTS FOR THE COMMERCIAL BASIN

BIOASSAY*

-. Mann-Whitney U-Test Results

Test Calculated Critical Decision

100% PARTICULATE PHASE

Citharichthys stigmaeu86 13.0 21.0 NSD

Acanthomysis sculpta ---- 21.0 NSD**

Acartia tonsa 15.0 21.0 NSD

SOLID PHASE

Acanthomysis sculpta 20.5 21.0 NSD

Neanthes arenaceodentata 13.0 21.0 NSD

Macoma nasuta ---- 21.0 NSD**

* The Mann Whitney U test was used in all cases. All data were evaluated at

the 95 percent confidence level. A statistically significant difference

exists for the comparison if the calculated value is greater than the

critical.

NSD - No significant difference in mortality.

NSD** - No significant difference in mortality determined by inspection of

data.

138. -. •

. . . . . . . . . .i- * i 

• =2 * . .- .
TABLE 4. THE CONCENTRATIONS (PPM) OF TRACE METALS, PESTICIDES (TICH),

PETROLEUM HYDROCARBONS, AND PCBs MEASURED IN THE TISSUES

OF CLAMS (MA COMA NASUTA) AND WORMS (NEANTRES ARENACEODENTATA)

AND IN SEAWATER AND SEDIMENTS. DATA ARE EXPRESSED ON WETWEIGHT BASIS

*Sample Cadmium Chromium Copper Mercury Silver PHF PCBs TICH

Macoma nasuta

C-i 0.150 0.520 2.000 0.050 0.130 <0.100 0.010 <0.0020

C-2 0.150 0.410 1.700 0.060 0.130 <0.100 0.004 <0.0010

C-3 0.120 0.420 2.200 0.030 0.100 <0.100 0.010 <0.0020

C-4 0.130 0.390 2.300 0.020 0.130 <0.100 0.010 <0.0020

C-5 0.140 0.400 1.700 0.040 0.080 <0.150 0.010 <0.0030

BASIN-i 0.120 0.340 2.800 0.060 0.120 <0.100 0.040 <0.0020

BASIN-2 0.090 0.370 4.200 0.060 0.090 <0.100 0.050 <0.0030

*BASIN-3 0.130 0.290 2.900 0.040 0.130 <0.200 0.040 <0.0020

BASIN-4 0.120 0.550 4.100 0.050 0.120 <0.100 0.040 <0.0020

BASIN-5 0.070 0.330 2.600 0.060 0.090 <0.100 0.050 <0.0020

Neanthes arenaceodentata

C-i 0.030 0.200 8.000 0.100 0.090 <1.500 0.090 <0.0020

C-2 0.020 0.100 6.000 0.100 0.070 <1.400 0.080 <0.0020

*C-3 0.040 0.100 7.000 0.100 0.070 <1.400 0.080 <0.0020

C-4 0.050 0.300 5.000 0.200 0.050 <4.000 0.240 <0.0050

C-5 0.030 0.200 6.000 0.200 0.070 <1.800 0.100 <0.0020

*BASIN-i 0.040 0.200 17.000 0.100 0.130 <1.800 0.100 <0.0020

BASIN-2 0.030 0.400 20.000 0.100 0.140 <2.000 0.130 <0.0030

*BASIN-3 0.030 0.200 10.000 0.100 0.080 <2.000 0.100 <0.0020

*BASIN-4 0.030 0.200 18.000 0.100 0.110 <1.600 0.090 <0.0020

*BASIN-S 0.030 0.200 18.000 0.100 0.120 <1.700 0.100 <0.0020

Seawater and Sediment Samples

WATER 0.001 0.011 0.002 0.0005 0.002 <0.004 0.0002 <0.00005

CONTROL 0.700 15.000 16.000 0.0980 0.800 <0.100 0.006 <0.0010

BASIN 0.900 26.000 210.000 2.7000 0.800 <0.100 0.025 <0.0010

C - Control.

*PHF = Petroleum hydrocarbon fraction.

PCB = Polychlorinated biphenyls quantitated as Aroclor 1254.

TICH - Total identifiable chlorinated hydrocarbon pesticides.

139
TABLE 5. MEAN CONTAMINANT CONCENTRATIONS (PPM) AND STATISTICAL

VALUES USED FOR DETERMINING BIQACCUKULATION POTENTIAL

IN THE COMMERCIAL BASIN SEDIMENT

Contaminant Control Test Common Caic Crit Decision ~

Macoma nasuta

*Cadmium 0.138 0.106 YES T:2.53 2.306 SD**

*Chromium 0.428 0.376 YES T:1.02 2.306 NSD

Copper 1.980 3.320 YES T:3.68 2.306 SD

*Mercury 0.040 0.054 YES T:1.72 2.306 NSD

Silver 0.114 0.110 YES T:0.30 2.306 NSD

Pesticides 0.002 0.002 YES T:0.53 2.306 NSD

PCB's 0.008 0.044 YES T:12.90 2.306 SD

Pet. Hydro. 0.110 0.120 YES T:0.45 2.306 NSD

Neanthes arenaceodentata

Cadmium 0.034 0.032 YES T:0.37 2.306 NSD

Chromium 0.180 0.240 YES T:1.10 2.306 NSD

*Copper 6.400 16.000 NO U:25.00 21.000 SD

Mercury 0.140 0.100 No U:17.50 21.000 NSD

Silver 0.070 0.116 YES T:3.81 2.306 SD

Pesticides 0.026 0.022 YES T:0.63 2.306 NSD

PCBs 0.118 0.104 NO U:17.00 21.000 NSD

Pet. Hydro. 2.020 1.820 NO U:17.50 21.000 NSD

*NSD = No significant difference.

NSD* - No significant difference determined by inspection of data.

*SD = Significant difference. 5

SD** =Significantly lower concentration in test sample.

*T - Students t-test.

U - Mann Whitney U-test.

140
.,..-..

TABLE 6. CONCENTRATION (PPB) OF MONOBUTYLTIN (MBTO), DIBUTYLTIN

(DBTO), AND TRIBUTYLTIN (TBTO) MEASURED IN THE SEDI- .. , MENTS AND SEAWATER FROM THE COMMERCIAL BASIN BIOASSAY*

Initial Final

MBTO DBTO TBTO MBTO DBTO TBTO ..

Seawater

Control seawater ND ND ND ND ND ND

" Particulate phase seawater 0.10 0.30 0.49 NS NS ND

Solid phase mysid tank water 0.67 2.00 0.20 0.03 0.05 0.25

Sediments

Control 62.50 72.50

Bulk Commercial Basin 780.00 NS

Solid phase - mysid tanks 318.00 155.00

Solid phase - clam tanks 610.00 267.50

Solid phase - worm tank NS 545.00

Clam Tissues

Control 0.26

Commercial Basin 2.82

Statistical Analysis of TBTO in Clam Tissue

Contaminant Control Test Common Calc Crit Decision

STBTO 0.26 2.82 NO U:16 U:15 SD

• TBTO was measured in Macoma nasuta tissues and estimates of bioaccumulation made on a wet weight basis of vg Sn/g tissue.

NS - Not sampled.

ND - Not detectable.

SD = Significant different.

141 *. . . .. . . . . .. . . . . * *. . . . . . . . . . . . .* . .',
survival was 84.8 percent and treatment survival was 87.2 percent. There was

no statistically significant difference in survival between controls and

treatments for either species.

Bioaccumulation

There was a significant accumulation of copper and silver in the tissues

of N. arenaceodentata and a significant accumulation of copper, PCBs, and

organotin in the tissues of M. nasuta. There was no significant accumulation

of other measured contaminants in the tissues of N. arenaceodentata or M.

oasuta when controls were compared with treatments for the Commercial Basin

bioassay. The significance of the silver accumulation is questionable as the

amounts determined in control and treatment sediments were similar

(0.800 ppm).

The total amount of organotins accumulated in clam tissues is shown in 1

Table 6. Treatments accumulated significantly more tin than controls. Control clam tissues were measured to contain 0.26 ppm organotin as TBTO. Clams

exposed to the Commercial Basin sediment accumulated 2.82 ppm organotin as

TBTO. These values were determined on a wet-weight basis and demonstrate that

organotins associated with sediments are bioavailable.

Organotin Measurements

The concentration of butyltin species in particulate phase water was

measured as: 0.10 ppb monobutyltin, 0.30 ppb dibutyltin, and 0.49 ppb

tributyltin. In solid phase water from mysid tanks, the initial concentration

of tributyltin was 0.20 ppb, about half that of particulate phase water. However, both monobutyltins and dibutyltins were significantly higher at 0.67 and

2.00 ppb, respectively. At the end of the solid phase mysid test, water from

these tanks was measured at 0.03 ppb monobutyltin, 0.05 ppb dibutyltin, and

0.25 ppb tributyltin (Table 6). Organotins were not detectable in the nearshore seawater obtained through the NOSC seawater system.

The concentration of solvent extractable tin (as TBTO) in control sediment was measured to be between 62.50 and 72.50 ppb. The bulk samples of Commercial Basin sediment (from collection chests) was measured to contain

780.0 ppb tin as TBTO. The concentration of tin in Commercial Basin sediment

from test tanks was measured to be between 318.0 and 610.0 ppb as TBTO. This

confirms that the amount of tin in the treatment sediment was relatively high

and in the control sediment relatively low. The amount of tin remaining in

the sediment from the solid phase mysid, clam, and worm tanks at the end of

the bioassay was 155.0, 267.5, and 545.0 ppb as TBTO, respectively (Table 6).

This decrease in TBTO concentration demonstrates that tins had leached off the

treatment sediment.

The co)mposition of control sediment is much different than Commercial

Basin sediment. In previous measurements of sediments from another control

site near the entrance to San Diego Bay, tributyl-tins were below the levels

of detection (27). This suggests that most of the tin found in our control

sediment is not TBTO, but other organically bound tins. Most of the tin in

the Commercial Basin sediment is probably tributylin-tin and its degradation

products. It has also been shown that sediment from the Commercial Basin

142

' i .. .. -. .. ? .. .:. . ..- L.i. .. .. .. . ... . ...... v ".'.'. -'.. ' '.," -' e'.." ,',.'.A'-,',.'1
collection site contains 77 percent tributyltin (27). To simplify the dis- -.

cussion, the concentration of organically extractable tin multiplied by 2.5

will be used as a relative TBTO concentration.

Sediment Characteristics

The mean grain size of the control sediment was 0.0981 mm. The composition was 81.0 percent sand with 10.6 percent silt and 8.4 percent clay. This

was classified as fine sand. The mean grain size of Commercial Basin sediment

was 0.0302 mm with a composition of 34.3 percent sand, 5.14 percent silt, and

14.3 percent clay. This sediment is classified as sandy-silt (31).

DISCUSSION

A standard dredged material bioassay was conducted on sediment contaminated with organotins collected from Commercial Basin in San Diego Bay. The

purpose of this study was to assess the toxicity and bioavailability of

organotins associated with sediment and to determine if this organotincontaminated sediment would qualify for ocean disposal. On the basis of

organotin field measurements of Commercial Basin sediment and water, and concentrations known to cause effects on sensitive planktonic organisms in the

laboratory, we anticipated this would be the first sediment from San Diego Bay

to produce significant mortalities from a standard sediment bioassay. As part

of a Navy program to study the fate and effects of organotins in the marine

environment, sediments were measured in a number of harbors. Measurements in

San Diego Bay showed that Commercial Basin sediment and water had the highest

concentrations of organotins. Sediment values ranged from 32 to 560 ppb TBTO.

I Surface water samples from Commercial Basin were measured between 0.01 and

0.18 ppb TBTO while bottom water samples varied from 0.11 to 0.55 ppb

TBTO (30).

A static renewal toxicity test using A. tonsa has estimated a 96-hour

LC-50 of 1.0 ppb TBTO. In this same study a 144-hour effective concentration,

or that concentration causing some effect on 50 percent of the animals after

144 hours, was calculated to be 0.4 ppb TBTO (29). Our previous work on the

mysid Metamysidopsis elongata has estimated a 96-hour LC-50 between 0.5 and

0.9 ppb TBTO for juvenile animals. For adults the LC-50 was estimated to be

about 3.0 ppb TBTO (27). In addition, it was determined that equivalent

tributyltin oxide concentrations prepared from stock chemical solutions and

leachates from antifouling coatings had the same effect on mysids (20).

Recent work at NOSC has estimated a 96-hour LC-50 of 0.6 ppb TBTO for juvenile

A. sculpta mysids and a 96-hour LC-50 of 1.7 ppb TBTO for adult A. scuipta

mysids. All of these factors led to the selection of Commercial Basin sediment as an example of organotin contamination that might cause an effect on

sensitive bioassay animals. A standard dredged material bioassay was used to '

predict the effects of organotins on bioassays required for future dredging

permits.

The measured concentration of TBTO in Commercial Basin sediment from

treatment tanks varied from 318 to 610 ppb extractable butyltin and confirmed

that we had collected contaminated sediment. These concentrations are lower

than concentrations measured for the bulk sediment from the collection chests

- (780 ppb TBTO) because treatment sediment was actually collected from test

*tanks and may have included some control sediment from the bottom layer of the

143

S . _. . . , .,2i
°.

tank. The concentration of TBTO in treatment sediment is approximately five

to ten times higher than in our control sediment. These high TBTO values are

similar to our previous measurements of Commercial Basin sediment.

Measurements of the water and sediment in solid phase and particulate

phase test tanks indicated that organotins were leached from the test sediment. Although organotins were not detectable in control seawater, initial

TBTO concentrations in mysid tanks measured on the first day of the test

varied from 0.20 ppb in solid phase water to 0.49 ppb in particulate phase

water. The concentration of TBTO in test sediment decreased concomitantly

during the test. These measurements confirmed that TBTO from the Commercial

Basin sediment was being released into test water. The speciated butyltin

measurements demonstrate that the more soluble and less toxic monobutyltin and

dibutyltin compounds were also released from the sediment.

Fish, clams, and worms all demonstrated high survival after continuous

exposure to TBTO. These results were predictable based on their tolerance to

other toxicants and results from previous bioassays. Due to their high sensitivity to organotins, significant mortalities in mysids and copepods exposed

to organotin-contaminated sediments were expected, but not observed. Control

and treatment mysid survival was 100 percent in the 96-hour particulate phase

tests, where TBTO concentrations were initially measured at 0.49 ppb. This

was not expected. The estimated 96-hour LC-50 for mysids is between 0.6 and

3.0 ppb TBTO and for copepods approximately 1.0 ppb TBTO. It is quite possible that the initial concentration of TBTO decreased during the 96-p ur

test. However, mysids and copepods were exposed to concentrations of fBTO

that approximated those which have previously produced significant effects.

In the 10-day solid phase test with mysids, treatment survival was 86 percent

and not significantly different than control survival of 95 percent. The concentration of TBTO varied between 0.20 and 0.25 ppb during the 10-day test.

Copepods also did not exhibit an effect after TBTO exposure. Treatment survival was 82 percent for animals exposed to 0.49 ppb TBTO while control survival

was 88 percent.

Considering the rationale for replacing chemical analyses with bioassays

for the regulation of dredged material disposal, perhaps these results should

have been expected. The Corps of Engineers Dredged Material Research Program

has shown that bulk metal analyses of test sediments do not correlate with

metal bioavailability (16). It has further been suggested that the magnitude of bioaccumulation does not always reflect sediment DDT concentration (15). h

Bioassay results give a normalized estimate for evaluating the potential for

environmental impact after ocean disposal. Further, bloassays eliminate

selecting which contaminants should be measured and which should be eliminated. This is particularly important when there is a chance of eliminating

the one contaminant which could be the most significant. The bioavailability

of contaminants in sediments is highly variable and dependent on a variety of

factors. These include the physical properties of the sediments, the chemical

state of the contaminants, and the chemical and biological parameters of the

water (9).

The bioavailability of coitaminants and their actual toxicity In seawater

is also highly variable. Although a minimum concentration of certain trace

metals is important for phytoplankton growth (8), the form of the chemical

state of those metals determines whether or not they are usable by the

144

• _' ..' ,'~~~... _-- '..... '.' ... ,f¢J2.. .. ..... '..-.''''"".''...e.--".".....,.,%
organisms (10). Studies on some species of phytoplankton show that growth

inhibition and copper uptake are related to cupric ion activity and not to

total copper concentration (28). Along with others, we have shown that toxicity to species used in this bioassay is also related to the state of the

cupric ion being tested (20). In experiments with mysids and brine shrimp

- nauplii, tributyltin was far more toxic than its degradation products,

dibutyltin and monobutyltin (27). The addition of sediment to test tanks

reduces the toxicity of copper to Neanthes arenaceodentata (18) while the type

of sediment influences copper toxicity and copper bioaccumulation (17). "

It follows that the presence of sediment in toxicity tests will probably

reduce toxicity and bioavailability of certain toxicants for a variety of animals. Since most organotin toxicity tests have been conducted without sediment, organotin toxicity has probably been overestimated. Toxic concentrations reported from those experiments are real but the abundance of naturally

occurring organics in those tests was probably abnormally low. Thus, standard

toxicity tests in glass aquaria without sediment do not realistically represent natural conditions. The addition of sediment, particulates, or other

organic compounds provides a much better approximation of natural conditions

in the marine environment. The expected toxicity of organotin-contaminated

sediment for Commercial Basin was not realized because the organotins were

probably not in a form readily available to the test animals.

It has been shown that organic chelators are often the most crucial factor in bioavailability of nutrients for phytoplankton growth in seawater (1, 10). t has also been suggested that, except for copper and iron,

complexing agents have a relatively minor effect on initial complexation in

seawater and that organic compounds adsorbed on the surface of sediment particles control the adsorption of metals (14). Although the actual chemical

mechanism is unclear, some organics found in natural sediments can reduce tox- "" ".

icity and bioavailability. This study suggests that organics in Commercial

Basin sediment reduce toxicity and bioavailability of organotins in that

sediment.

In addition to naturally occurring organic chelators in sediments that

reduce toxicity and bioavailability, animals also have the ability to sequester and detoxify contaminants. Since previous measurements of Commercial -"

Basin sediment have shown elevated levels of copper and organotin, it is not

surprising that M. nasuta bioaccumulated significant amounts of each of these

con'aminants. The environmental significance of the bioaccumulation estimate

is unclear. Treatment clams were found to accumulate organotins to a concentration an order of magnitude above control clams (2.82 ppm TBTO compared to

0.26 ppm TBTO), and a factor of four above Commercial Basin sediment. Since

-. the animals survived the experiment, these internal concentrations are apparently sublethal. Accumulated tins were probably modified by the animals to

become biologically unavailable. Accumulated tins could have combined with

lipids to reduce toxicity. They could have been bound to metallothioneins (19) or sequestered within cellular organelles (7). In each case, there

is a reduced opportunity for toxic expression.

Thus, when estimating the potential toxicity of organotin antifoulant

Pleachates from Navy hulls to marine organisms, more effort should be directed

.- toward duplicating natural conditions. This will prevent overestimating toxicity values and reduce the significance of questionable values currently

145

• . . -
appearing in the literature. For our purposes, however, organotincontaminated sediments from Commercial Basin, San Diego Bay, would qualify for

ocean disposal under the present guidelines. Questions could be raised about

the significant uptake of copper, the potential accumulation of organotins, or

even the validity of the bioassay itself. With all its shortcomings, the bioassay as conducted here is probably the best available estimator of environ- _.or

mental impact after ocean disposal because it accounts for bioavailability.

Changes could be made in species selection, test containers, test duration,

etc.; but as a regulatory tool, it is probably all that could be expected at

this time.

The other problem is that new contaminants like organotins are not well

known. As they are studied further, new insight should be gained into improving the required ecological evaluation of dredged material. The Navy research programs to expedite dredging and study the fate and effects of

organotins in the marine environment will help guide the assessment of the

potential for environmental impact. However, as the use of organotins increases, bioassays should include an assessment of the potential for bioaccumulation of these compounds. Further, much additional work will be required

to fully understand the chemistry and bioavailability of organotins and to

predict their effect on the marine environment.

CONCLUSIONS

In conclusion, the results of this bioassay suggest that the sediment

from Commercial Basin, San Diego Bay, should not have a significant impact on

the marine environment if discharged into ocean waters. These results also

suggest that organotins found in sediments at relatively high levels are not

necessarily toxic to marine life. It is probable that the organotins present

were not as bioavailable as originally anticipated and that the approach in

testing organotin toxicity should be re-evaluated in terms of environmental .'.-

significance as well as adsorption on sediment and detoxification by animals.

ACKNOWLEDGEMENTS

This study was sponsored through the Environmental Protection Office at

the Naval Facilities Engineering Command in a program to Expedite Navy

Dredging. Analytical support was provided through the Energy Office of the

Naval Material Command in a program to determine the Fate and Effects of

Organotins in the Marine Environment.

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Affecting Primary Production in the Cromwell Current Upwelling," J. Exp.

Mar. Biol. Ecol., Vol 3, pp 191-199.

2. Berhard, M., and Zattera, A. 1975. "Major Pollutants in the Marine

Environment," Marine Pollution and Marine Waste Disposal, Pergamon Press,

Ltd., Oxford.

3. Dixon, W. J., and Massey, F. J. 1969. Introduction to Statistical NNW---

Analysis, McGraw-Hill, New York.

146

.. . . . I . . . . . . . . . . . . . . . . . . m m -
4. Emery, K. 0., and Butcher, W. S. 1952. "Submarine Geology off San

Diego, California," J. Geology, Vol 60, No. 6, pp 511-548.

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"Ecological Evaluation of Proposed Discharge of Dredged Material Into

Ocean Waters," Environmental Effects Laboratory, U. S. Army Engineer

Waterways Experiment Station, Vicksburg, Miss.

7. George, S. G., Pirie, B. J. S., Cheyne, A. R., Coombs, T. L., and

Grant P. T. 1978. "Detoxication of Metals by Marine Bivalves: An

Untrastructural Study of the Compartmentation of Copper and Zinc in the

Oyster Ostrea edulis," Mar. Biol., Vol 45, pp 147-156.

8. Guillard, R., and Ryther, J. 1962. "Studies on Marine Planktonic

Diatoms," Can. J. Microbiol, Vol 8, pp 299-239.

- 9. Jennett, J. C., Effler, S. W., and Wixson, B. G. 1980. "Mobilization

and Toxicological Aspects of Sedimentary Contaminants," Contaminants and

Sediments, Vol 1: Fate and Transport, Case Studies, Modeling, Toxicity,

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Trace Metals and Chelation, and General Discussion," J. Mar. Biol. Assn.

U.K., Vol 44, pp 87-109.

11. Krett, S. M. 1979. "Productivity and Diversity of Phytoplankton in

Relation to Copper," San Diego State University Master's Thesis. 141 pp.

. 12. Marine Bioassay Laboratories. 1982. "Technical Evaluation of Environmental Impact Potential for Proposed Ocean Disposal of Dredged Material

From Los Angeles Harbor," Prepared for Los Angeles Harbor Department.

13. Meador, J. P., U'Ren, S. C., and Salazar, M. H. 1984. "A Flow-through

Bioassay System for the Evaluation of Organotin Antifouling Compounds,"

Water Research, Vol 18, pp 647-650.

14. Morel, F. M. M., and Morel-Laurens, N. M. L. 1981. "Trace Metals and

Plankton in the Oceans," C. S. Wond, E. Boyle, K. W. Bruland, J. D.

Burton, and E. D. Goldger, eds., Trace Metals in Sea Water, Plenum Press

New York, pp 841-869.

15. Nathans, M. W., and Bechtel, T. J. 1977. "Availability of SedimentAdsorbed Selected Pesticides to Benthos with Particular Emphasis on

Deposit-Feeding Intauna," Technical Report D-77-34, U.S. Army Engineer

Waterways Experiment Station, Vicksburg, Miss.

16. Neff, J. W., Foster, R. S., and Slowey, J. F. 1978. "Availability of

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Waterways Experiment Station, Vicksburg, Miss.

147

* A * --. ...
*17. Pesch, C. E. 1979. "Influence of Three Sediment Types on Copper

Toxicity to the Polychaete Neanthes arenaceodentata," Mar. Biol., Vol 52,

pp 237-245.

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Toxicity Tests with the Polychaete Neanthes crenaceodentata,

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19. Roesijadi, G. 1981. "The Significance of Low Molecular Weight

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20. Salazar, M. H., and Salazar, S. M. 1981. "Effects of Organotins on

Marine Organisms." (Unpublished)

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(P-272)," Prepared for Naval Station, San Diego. Naval Ocean Systems

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Technical Report (Unpublished).

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Dredged Sediments for NAVSTA San Diego Drydock Facility," Prepared for

Naval Facilities Engineering Command. Naval Ocean Systems Center

Technical Report (Unpublished).

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Long Beach Turning Basin Expansion Project," Prepared for Naval

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Leachates in the Marine Environment," Progress Report I Oct 82-30 Sept 83

Prepared for Energy Research and Development Office, David W. Taylor Ship

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(Unpublished).

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Vol 34, No. 4, pp 511-529.

148

7 . .... . . . .
29. U'Ren, S. C. 1983. "Acute Toxicity of Bis(tributyltin) Oxide to a

Marine Copepod. Mar. Poll. Bull., Vol 14, No. 8, pp 303-306.

30. Valkirs, A. 0., Seligman, P. F., Taylor, V., Stang, P. M., and

Lieberman, S. H. 1984. "Measurement of Butyltin Compounds in San Diego

Bay," (To be Submitted to Environmental Science and Technology).

31. Wentworth, C. K. 1922. "A Scale of Grade and Class Terms for Plastic

Sediments," J. of Geology, Vol 30, pp 377-392.

32. Zar, J. H. 1974. "Biostatistical Analysis, Prentice-Hall, Englewood

Cliffs, N.J.

33. Zirino, A., Lieberman, S. H., and Clavell, C. 1978. "Measurement of Cu

and Zn in San Diego Bay by Automated Anodic Stripping Voltammetry,"

Env. Sci. Tech., Vol 12, No. 1, pp 73-70.

-..-

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CHARACTERIZATION OF SEDIMENT CONTAMINATION UTILIZING

BIOASSAY/BIOACCUMULATION TESTING

J. M. Mansky

U.S. Army Corps of Engineers

New York District

26 Federal Plaza

New York, New York 10278-0090

ABSTRACT

The Ocean Dumping Criteria specified biological

tests of dredged material to evaluate short-term '*.

toxicity of ocean disposal operations (bioassay tests)

and the potential for long-term chronic effects

through the bioaccumulation of harmful contaminants.

A statistical analysis of 150 three-phase bioassay/

bioaccumulation tests conducted on sediment from New

York Harbor indicated that only a few dredging projects consisted of sediment that would be of ecological concern if disposed in ocean waters. Liquid and

suspended particulate phase bioassays showed that disposal of the dredged material would result in insignificant impact to the water column. Based on the solid

phase bioassays, 4 percent of the dredging projects

indicated environmentally significant mortality potential to benthic life.

Bioaccumulation analyses for petroleum

hydrocarbons (PHC), polychlorinated biphenyls (PCBs),

DDT, cadmium, and mercury were conducted on organisms

surviving the 10-day solid phase bioassay tests. Bio- ......

accumulation of statistically significant levels of

PHC was found to be common for all three organisms

tested. PCB bioaccumulation was more common in the

marine worm (Nereis virens). DDT was never found to

be bioaccumulated in statistically significant

amounts. All three organisms exhibited a very low

bioaccumulation potential for cadmium and mercury.

Some predictions were possible for the bioaccumulation

of PHC and PCB within the same organism and for the

same contaminant between organisms; predictions were

not possible for cadmium or mercury.

150

........................ .. . . * . .... .*. . . *.*. 
INTRODUCT ION

The continued viability of the Port of New York and New Jersey depends

upon the dredging of an average of 7.6 million cubic meters of sediment each

* year. The urbanized nature of the metropolitan area precludes the upland % -. ." disposal of large quantities of dredged material. Disposal of over 90 percent

of the sediment dredged from the Port has taken place at the "Mud Dump Site" *6' *.

located approximately 11 km east of New Jersey and 20 km south of New York

(Figure 1).

r -

NEWYOAW

.1 -P

Figure 1. New York Harbor showing major rivers

and "Mud Dump"

Two previous papers (5,6), which were presented at the Sixth and Seventh

Joint U.S./Japan Experts Meeting on the disposal of toxic sediments, explained

the background of the sediment contamination problem in the New York Harbor

area. Due to the sediment contamination, disposal of dredged material has

been of environmental concern since the late 1960's.

The Marine Protection, Research, and Sanctuaries Act of 1972 (Public

Law 92-532), more commonly known as the "Ocean Dumping Act," regulates all

types of ocean dumping, including dredged material. In accordance with the -.

Ocean Dumping Act, the US Environmental Protection Agency (EPA) in 1977

promulgated regulations and criteria (2) to determine the potential environmental impact of the disposal activity. The Ocean Dumping Criteria (40 CFR

Parts 220 through 229) specified biological tests to consider short-term

151 7. 777.
*" toxicity of dumping operations (bioassay tests) and the potential for long-

"* term chronic effects through the bioaccumulation of harmful contaminants. A

previous paper (1), presented at the Sixth Joint U.S./Japan Experts Meeting on

the Disposal of Toxic Sediments, provides additional information on legal

requirements of proposed operations involving the transportation of dredged

material for dumping into ocean waters.

Since the inception of the requirement of three-phase bioassay/ bioaccumulation testing in 1979, approximately 30 tests per year have been

conducted on sediment from New York Harbor, which is proposed for ocean disposal. This paper presents a statistical analysis of the 150 tests reviewed

by the New York District Corps of Engineers.

BIOASSAY ANALYSIS

* Introduction

In accordance with EPA's Ocean Dumping Regulations (2), liquid phase,

suspended particulate phase, and solid phase bioassays are required for the

* proposed dredged material utilizing the test species as discussed below. -.

The liquid phase is considered to be the centrifuged and 0.45-micron

, filtered supernatant remaining after I hr of undisturbed settling of the mix-

- ture resulting from a vigorous 30-min agitation of one part bottom sediment

from the dredging site with four parts water collected from either the dredging site or the disposal site, as appropriate for the type of dredging operation. The suspended particulate phase is the supernatant obtained prior to

centrifugation and filtration, while the solid phase is considered to be all

material settling to the bottom within I hr.

As pointed out in the Implementation Manual for the Ecological Evaluation

of Proposed Discharge of Dredged Material into Ocean Water (1), "...the liquid

phase may be analyzed in either of two ways, as specified in paragraph 227.13

(13)(c)(2) of The Register ....The liquid phase may be analyzed chemically and

the results evaluated by comparison to water quality criteria... (or) if the

water quality approach is not taken, the liquid phase must be evaluated by

bioassays....".

The New York District Corps of Engineers has adopted the direct bioassay

approach as being more appropriate since the liquid phase may contain major

constituents not included in the water quality criteria and since there is

reason to be concerned about possible synergistic effects. The liquid phase

bioassay is appropriate in evaluating the total net impact of dissolved chemical constituents released from the sediment during disposal operations.

For the liquid and suspended particulate phase bioassays, lethal concentrations (LC50) and effective concentrations (EC50) were used. LC50's are .---

those concentrations of liquid or suspended particulate phase resulting in

50 percent mortality; they were determined for the animal species Menidia

menidia, Mysidopsis bahia, and Acartia tonca. EC50 is that concentration of

liquid phase resulting in 50 percent inhibition; it was determined for the

phytoplankton species Skeletonema costatwn. Liquid and suspended particulate

phase bioassays are conducted over a 96-hr (4-day) period.

152 "

* - *.* - ~ *.-. ,,. - - . - -*- - - - - - - - - --- -
The solid phase bioassay is a 10-day exposure which is run concurrently

on three sediments: test, reference, and control. The reference sediment

represents existing background conditions in the vicinity of the dump site but

away from the influence of any disposal operation, while the control sediment

represents a non-toxic substrate utilized to monitor testing conditions while

the solid phase bioassay is being conducted. Results of the solid phase bioassay are utilized to predict the impact of the dredged material on benthic organisms.

Analysis -..

Based upon the LC50 (or EC50) for the most sensitive species for the

liquid or suspended particulate phase bioassays, the LPC (Limiting Permissible

Concentration) values are determined by applying a safety factor of 100 (LC5O

or EC50/100). The sediment can be authorized for ocean disposal only if the

concentration of the disposal water in both the liquid and suspended particulate phases is diluted to below that of the LPC after 4 hr of initial mixing.

The mixing and dilution of the proposed dredged material is evaluated by

use of the Tetra Tech computer model. A description of the model has been .' '.

published as Technical Report D-78-47 of the Corps' Dredged Material Research

Program, and is entitled "Evaluation and Calibration of the Tetra Tech Dredged

Material Disposal Models Based on Field Data" (4). A study was conducted giving examples of dilutions resulting from typical disposal operations using

dredged materials found in the New York District; this study is entitled

"Discussion of Dredged Material Disposal Models and Their Application for the

New York District" (3). Using the example in this study that most closely

approximates the disposal operations conducted at the Mud Dump Site, the

dilution after 4 hr would be 0.0047 percent. The Tetra Tech Model uses the

total initial volume of dredged material and, therefore, the resultant concentration serves for both the liquid phase and the suspended particulate phase.

For the solid phase bioassay, the results are evaluated for biological

and statistically significant differences in mortality between test organisms

which are subjected to both proposed dredged sediment and to a reference

sediment.

The Implementation Manual specifies that differences in survival of the

test organisms in the reference and test treatments be evaluated either individually by species or on a pooled community basis. The Manual states that

the LPC for the solid phase is exceeded when the difference in mortality

between animals In the reference and test sediments is statistically significant and greater than 10 percent.

Results

Figure 2 presents the results of liquid phase bioassays, while Figure 3

presents the results of the suspended particulate phase bioassays. Results

are expressed as cumulative percentages plotted on probability paper. It

should be noted, as indicated above, that LC50 values of 0.47 percent or less

would result in the iimiting permissible concentration being exceeded, and

therefore unacceptable water column impacts are anticipated. As indicated by

these two figures, the LPC has never been exceeded in either the liquid or

suspended particulate phase bioassays. In order to determine the relationship

153

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between the responses of the organisms in each of the two phases and between

organisms in the same phase, the correlation coefficient was calculated. It

was determined that the highest correlation coefficient (r = 0.53) was found

when comparing the response of Mysidopsis in the liquid phase bioassay with

Mysidopsis in the suspended particulate phase. An r value of 0.53 indicates 1

that there is a moderate positive correlation for this comparison. For all N

other comparisons, the correlation value was less than 0.30 and it can therefore be stated that there is no relationship between the responses of the

organisms in the same phase bioassay or between the same organism in the

liquid and suspended particulate phase bioassay.

Species used in the solid phase bioassay are Palaemonetes sp. (grass

shrimp), Mercenaria mercenaria (hard clam), and Nereis sp. (polychaete worm). .

Results of the solid phase bioassay are presented in Table 1. It can be

observed that Palaemonetes showed the most occurrences (9.2 percent) in which

the test had statistically significant greater mortality than the reference.

This is followed by 5.9 percent for Nereis and 2.0 percent statistically

significant for Mercenaria. When considering survival differences, which are

of ecological significance (i.e. greater than 10 percent), only 3.9 percent of

the projects tested had mortality in a test organism that was more than

10 percent higher than the reference.

TABLE 1. SOLID PHASE BIOASSAY RESULTS EXPRESSED AS A PERCENTAGE IN

WHICH TEST RESULTS WERE GREATER THAN REFERENCE RESULTS

(STATISTICALLY SIGNIFICANT (SS) AT THE 95 PERCENT

CONFIDENCE LEVEL)

Species SS > 10 percent SS < 10 percent Not SS

Palaemonetes 2.6 6.6 90.8

Mercenaria 0.0 2.0 98.0 "

Nereis 1.3 4.6 94.1

BIOACCUMULATION ANALYSIS

Introduction

EPA's Ocean Dumping Regulations (2) require that the potential for bioaccumulation of contaminants from dredged material be evaluated. Field

sampling programs are preferred since the animals are exposed over the long

term to the conditions of mixing and sediment transport actually occurring at

the disposal site. The limitation of field sampling is that it is technically

valid only where there exists an historical record for the proposed operation

being evaluated. Since this historical information does not exist for the Mud

Dump Site, a laboratory assessment of bioaccumulation potential is conducted

for New York Harbor sediments that are proposed for ocean disposal.

155

........ .. .....- .. -. ,-....-:... . , , . ... ... .- "..
At the end of the solid phase test, surviving organisms are placed in

separate aquaria in clean, sediment-free water to void the digestive tracts of

all sediment. Where appropriate, the shell or exoskeleton is removed before

chemical analysis is conducted.

Analysis

The London Dumping Convention (7) requires an evaluation of bioaccumulation for sediment which may contain contaminants that cannot be ocean disposed

in other than trace amounts. The evaluation is conducted to determine if

there will be significant undesirable effects on human health. "

For sediment from New York Harbor that is proposed for ocean disposal,

bioaccumulation analysis is conducted for total petroleum hydrocarbons (PHC),

polychlorinated biphenyls (PCB), DDT, mercury (Hg), and cadmium (Cd). Results

of the test phase of the bioaccumulation analysis are statistically compared

at the 95 percent confidence level with the results of the reference phase

analysis. (Tissue from the control phase is frozen for future analysis,

should the need be demonstrated.)

Results

Table 2 presents information on the mean, standard deviation, and maximum

values observed for PHC, PCB, Hg, and Cd. Although DDT has been analyzed in

each of the 150 tests reported in this paper, it has never been found above

the detection limit of 0.02 ppm. Comparing the data, it can be observed that

there is a tendency for bioaccumulation to be highest in Nereis, with

TABLE 2. BIOACCUMULATION RESULTS EXPRESSED IN

PARTS PER MILLION

Variable PHC PCB Hg Cd

Palaemonetes

Mean 6.26 0.06 0.22 0.29

Standard deviation 16.57 0.06 0.10 0.14

Maximum 121.81 0.29 1.30 1.76

Mercenaria

Mean 4.84 0.05 0.24 0.28

Standard deviation 17.78 0.02 0.25 0.07

Maximum 184.40 0.19 2.30 0.67

Nereis

Mean 7.13 0.09 0.26 0.27

Standard deviation 11.53 0.09 0.24 0.06

Maximum 55.87 0.62 2.90 0.78

156

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*.* 

.... ,- -.- - --

bioaccumulation in Palaemonetes and Mercenaria equivalent for PCB, Cd, and Hg.

The low PHC bioaccumulation value for Mercenaria may be due to a proportionately lower quantity of body lipid present within the tissue, which is

analyzed and reported as PHC bioaccumulation.

Table 3 presents the percentage of times that bioaccumulation of a con- -]L

taminant in each organism is statistically significant at the 95 percent confidence interval, when compared to bioaccumulation from a reference sediment.

Of the contaminants evaluated, PHC has the highest occurrence of statistically

significant bioaccumulation. Statistically significant PCB bioaccumulation in

Nereis is far more common than in the other two species. Bioaccumulation of

Cd and Hg in statistically significant quantities is a rare occurrence found

in only about 2 percent of the cases analyzed.

TABLE 3. BIOACCUMULATION RESULTS EXPRESSED AS PERCENTAGE IN WHICH

TEST RESULTS WERE GREATER THAN REFERENCE RESULTS (STATISTICALLY SIGNIFICANT AT 95 PERCENT CONFIDENCE LEVEL)

Contaminant PaZaemonetes Mercenaria Nereis

PHC 25.0 44.1 55.9

PCB 6.6 9.2 25.0

DDT 0.0 0.0 0.0

Cd 2.0 3.3 2.0

Hg 2.0 2.0 0.7

Interpretation of statistically significant quantities of these contaminants was initially a source of technical debate. Once the management of

dredged material disposal to prevent unreasonable degradation of existing

environmental conditions was accepted as a short-term goal, an interpretive

guidance was developed. The details of the development and implementation of

the interpretive guidance (matrix) for PCB are presented in Engler et al. (1).

Later, guidance values for DDT, mercury, and cadmium were developed, and are - .-

implemented utilizing the same approach as for the PCB matrix. To date, no

matrix has been developed for PHC bioaccumulation. The matrix, as currently

utilized for New York Harbor sediment, is presented in Table 4. The percentage of times in which test results are statistically significant and above the

matrix value is presented in Table 5. In only 4 percent or less of the cases

was the bioaccumulation value statistically significant and greater than the

matrix. Nereis exceeded the matrices the least number of times.

157

....................................................
TABLE 4. INTERPRETIVE GUIDANCE (MATRIX) VALUES EXPRESSED IN r*-.,

PARTS PER MILLION

Species PHC PCB DDT Cd Hg

Palaemonetes 0.1 0.04 0.3 0.2

Mercenria -- 0.1 0.04 0.3 0.2

Nereis -- 0.4 0.04 0.3 0.2

TABLE 5. BIOACCUMULATION RESULTS EXPRESSED AS A PERCENTAGE IN WHICH

TEST RESULTS WERE GREATER THAN REFERENCE (STATISTICALLY

SIGNIFICANT AT 95 PERCENT CONFIDENCE LEVEL) AND ABOVE

MATRIX VALUE

Species PHC PCB DDT Cd Hg

PaZaemonetes -- 3.9 0.0 2.0 2.0

Mercenaria -- 3.9 0.0 3.3 2.0

Nereis 0.7 0.0 2.0 0.7

Analysis was conducted to determine if bioaccumulation of a contaminant

in one organism could be used to predict bioaccumulation of that contaminant

in one of the other two organisms. For PHC (Table 6), the highest occurrence

(35.5 percent) of statistically significant bioaccumulation for the same

sediment was found in comparing Mercenaria and Nereis. The smallest value

TABLE 6. PHC BIOACCUMULATION OCCURRENCE OF STATISTICAL

SIGNIFICANCE (SS) IN TWO SPECIES

Species Percent SS

Paiaemonetee and Nereis 21.17

Paiaemonetes and Mercenaria 20.4

Mercenaria and Nereis 35.5

(20.4 percent) was Palaemonetes and Mercenaria. Table 7 presents information

on the occurrence of PHC bioaccumulation when comparing two species. Although

Palaemonetes had the lowest number of statistically significant bioaccumulation cases, it can be observed that when it did occur, it was very likely to

158

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4U' "L7 -7" " ---

TABLE 7. PERCENT OCCURRENCE OF PHC BIOACCUMULATION MATCHING.-

TWO SPECIES

Percent Occurrences

Species Number SS Occurrences PAL MER NER

Palaemonetes (PAL) 38 -- 82 87

Mercenaria (MER) 66 46 -- 80

Nereis (NER) 84 39 64 --

occur in ercenaria (82 percent) and Nereis (87 percent) as well. The -

occurrence of statistically significant bioaccumulation of PHC in Mercenaria

could also be used to predict PHC at a high level (80 percent) in Nereis.

Mercenaria and Nereis were the two species with the highest (5.3 percent)

simultaneous occurrence of statistically significant PCB bioaccumulation

(Table 8). The values presented in Table 8 are considerably lower than the

corresponding values for PHC found in Table 6. When comparing the occurrence

of PCB bioaccumulation in two species (Table 9), the highest values are found

for Paiaemonetes compared to Mercenaria (70 percent) and Nereis compared to

Palaemonetes (70 percent).

TABLE 8. PCB BIOACCUMULATION - OCCURRENCE OF STATISTICAL

SIGNIFICANCE (SS) IN TWO SPECIES

Species Percent SS

Falaemonetes and Nereis 4.0

PaZaemonetes and Mercenaria 4.6

Mercenaria and Nereis 5.3

TABLE 9. PERCENT OCCURRENCE OF PCB BIOACCUMULATION MATCHING

TWO SPECIES

Percent SS Occurrences

Species Number SS Occurrences PAL MER NER

Fa~aemonetes (PAL) 10 -- 70 16

Mercenaria (MER) 14 50 -- 21

Nereis (NER) 38 70 58 --

159
IiStatistically significant bioaccumulation occurrences for all organisms

were so rare for cadmium and mercury that no comparison between species was

appropriate. In only two cases out of nine did two species bioaccumulate

statistically significant cadmium from the same sediment. For only one case

out of six was mercury of statistical significance bioaccumulated in two

species from the same sediment.

An analysis was conducted of bioaccumulation of organic contaminants (PHC and PCB) within the same species for the same sediment. The only comparison

which indicated a possibility for prediction was for PHC, based upon PCB

results (Table 10). Where PCB of statistical significance was bioaccumulated

in Palaemonetes, 70 percent of the cases also had statistically significant

bioaccumulation for PHC.

TABLE 10. BIOACCUMULATION OCCURRENCE OF STATISTICALLY SIGNIFICANT

RESULTS FOR PHC BASED UPON PCB RESULTS

Number Percent

Species Occurrences Occurrences

Palaemonetes 7 70

Mercenaria 7 50

Nereis 3 8

For Mercenaria, the comparison value decreased to 50 percent. The

occurrence of cadmium and mercury bioaccumulation was so low that a statistical comparison was not valid.

CONCLUSIONS

A statistical analysis of 150 three-phase bioassay/bioaccumulation tests

conducted on sediment from New York Harbor indicated that only a few dredging

projects consisted of sediment of ecological concern if disposed in ocean

waters. Liquid and suspended particulate phase bioassays showed that for the

dredged material analyzed, disposal would result in an insignificant impact to

the water column. Solid phase bioassays showed that less than 4 percent of

the dredging projects indicated environmentally significant mortality

potential to benthic life.

Bioaccumulation of statistically significant levels of PHC was found to

be common for all three species. PCB bioaccumulation was most common in

Nereis. All three species exhibited a very low bioaccumulation potential for

DDT, cadmium, and mercury. Some prediction was found to be possible for

finding PHC or PCB bioaccumulation in two species for the same sediment. In

the comparison of finding two of the analyzed contaminants in the same species

for the same sediment, only PHC compared to PCB bioaccumulation showed any

prediction possibility.

160
e n .-"-Z"n ...

REFERENCES

1. Engler, R. M., Peddicord, R. K., Wright, T., and Pierce R. J. 1982 (Mar).

"Ocean Disposal of Contaminated Dredged Material: A Case Study," Management of Bottom Sediments Containing Toxic Substances; Proceedings of the

6th U.S./Japan Experts Meeting, US Army Water Resources Support Center,

Fort Belvoir, Va.

2. Federal Register. "Ocean Dumping: Final Revision of Regulations and

Criteria," Part VI, 42(7), January 1977.

3. Johnson, B. H. 1979. "Discussion of Dredged Disposal Models and Their

Application for the New York District," Unpublished Report, US Army Engineer Waterways Experiment Station, Vicksburg, Miss.

4. 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, US Army Engineer Waterways Experiment Station,

Vicksburg, Miss.

5. Suszkowski, D. J. 1983 (Oct). "Studies on Capping of Contaminated

Dredged Material by the New York District, Corps of Engineers," Management

of Bottom Sediments Containing Toxic Substances; Proceedings of the 7th

U.S./Japan Experts Meeting, US Army Water Resources Support Center, Fort

Belvoir, Va.

6., Suszkowski, D. J., and Mansky, J. M. 1982 (Mar). "The Disposal of

Sediments Dredged from New York Harbor," Management of Bottom Sediments

Containing Toxic Substances; Proceedings of the 6th U.S./Japan Experts

Meeting, US Army Water Resources Support Center, Fort Belvoir, Va.

7. US Environmental Protection Agency. 1979. "London Dumping Convention,

Regulations, Guidelines and Procedures," Office of Water Programs, -tWashington, DC.

.'- - -

161

W.-i12
IDENTIFICATION OF PROMISING CONCEPTS FOR

TREATMENT OF CONTAMINATED SEDIMENTS

N. R. Francingues, Jr.

Environmental Laboratory

US Army Engineer Waterways Experiment Station %

Vicksburg, Mississippi 39180

ABSTRACT

Because of the nature and extent of contamination

associated with sediments along our highly developed

waterways and harbors, many of the sediments being

dredged in maintenance projects are unsuitable for disposal by conventional methods. In some cases, these

sediments are highly contaminated and have been identified as part of Superfund clean-up projects. Examples include Commencement Bay, Washington; Waukegan

Harbor, Illinois; and New Bedford Harbor, Massachusetts. In such cases, the dredging operation may

require novel approaches to the treatment and disposal

of highly contaminated bottom sediments. This paper

identifies promising concepts for the management and

treatment of contaminated sediments to be disposed in

an upland site.

INTRODUCTION

The Corps of Engineers (CE) dredges annually over 290,000,000 cu m in

maintenance dredging operations and about 78,000,000 cu m in new work dredging

operations. Over 90 percent of the total volume of dredged material is considered uncontaminated. However, the potential presence of contamination has

generated concern that dredged material disposal may adversely impact on water

quality and aquatic or terrestrial organisms. Since many of the waterways are

located in industrial and urban areas, sediments may be contaminated with

wastes from these sources. In addition, sediments may be contaminated with

chemicals from agricultural practices and uncontrolled chemical releases.

Recently, the CE has proposed a technically feasible and environmentally

srund management approach or strategy to the disposal of dredged material

(Figure 2) (2). This strategy is based on results of many years of research

and dredging experience by the CE and others. The approach presents a number

ot variations for each major alternative of open-water and confined disposal,

each having some influence on the fate of contaminants at disposal sites. The

management strategy provides an evaluative framework for assessing and W.

162

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choosing an appropriate alternative for disposal of materials ranging from

clean sand to highly contaminated sediments. The detailed technical approach

consists of the following:

a. Initial evaluation to assess contamination potential.

b. Selecting a potential disposal alternative.

c. Identifying potential problems associated with that alternative.

d. Testing to evaluate the problems.

e. Assessing the need for disposal restrictions.

f. Selecting an implementation strategy.

g. Identifying available control options.

h. Examining design considerations to evaluate technical and economic

feasibility.

i. Choosing appropriate control measures and technologies.

The management strategy (Figure 1) is currently being used and documented

at several ongoing CE field demonstration projects. Results of these field

activities will be used to further refine the management approach.

As part of the field demonstrations, innovative concepts for the management and treatment of highly contaminated dredged material in confined disposal operations will be evaluated. Systems will be adapted or developed that

can be incorporated into existing dredging and disposal operations. Such systems may include techniques for separation and classification of highly contaminated material from that which has low-level contamination, and subsequent

treatment of contaminated liquid and solids. The purpose of this paper,

therefore, is to identify promising concepts and technologies for treating

contaminated dredged material placed in confined upland disposal environments.

CONFINED DISPOSAL OF CONTAMINATED DREDGED MATERIAL

Overview of Confined Disposal

Before we can develop concepts for the treatment of contaminated dredged

material confined in upland disposal sites, it is important that we understand

the fundamental disposal operations, potential contaminant mobility pathways,

and various options for control of migrating contaminants.

Confined upland disposal involves the placement of dredged material in

environments not inundated by tidal waters (Figure 2). Upland disposal sites

are normally diked, confined areas that retain the dredged solids while allowing the carrier water to be released, and as such are most often associated

with hydraulic dredges (pipeline or hopper with pump-out capability).

Upland sites can also accept dredged material that has been dewatered

elsewhere and transported in by truck or rail (if hydraulically dredged) or

has simply been loaded directly into trucks or railcars by mechanical dredges.

Upland disposal sites may be located immediately adjacent to, or removed great

distances from, the dredging site. ,6 '

164 - - .

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*," "'.'' + , ." ' '. " +" ," " -' , -+ ' '- ' " % " " , ...- " . ' "' ,' . ", % ' % ''. ' .' . '. - - %'- '-' .'. %'' ' ....... .. ... ..€P ..+ ..,. ,_ ..... +' e_,r P_ .€ .. . ..+.... -. ..- ..._ _ . . .. . .. -_ _ .-.+ ' ,p
MOUNDED COARSE-GRAfNED

DREDGED MATERIAL

--DEAD ZONE

- .... . .WEIR

• 'INFLUENT 1 " : - AREA FOR SEDIMENTATION . . ... - T _.-T 7 . EFFLUEN

DEAD ZONE* _

PLAN

:.--..

INFLUENT PONDING

DEPTH FREEOARD

.......... ,

COARSE-GRAINED ' AREA FOR FINE-GRAINED EFFLUENT

DREDGED MATERIAL DREDGED MATERIAL STORAGE

CROSS SECTION

Figure 2. Conceptual diagram of a confined dredged material

disposal site

The two objectives inherent in design and operation of containment areas

*' are to provide adequate storage capacity to meet the dredging requirements and

to attain the highest possible efficiency in retaining solids during the

dredging operation. Basic guidelines for design, operations, and management

of containment areas are presented by Palermo et al. (10) and Montgomery

, et al. (8).

Physicochemical Conditions

When dredged sediments is placed in an upland environment, drastic physicochemical changes occur (Figure 3). As soon as the dredged material is

*: placed in a confinement and allowed to be exposed to the atmosphere, oxidation

processes begin. The effluent water initially is dark in color and reduced

with little oxygen as it is discharged from a disposal pipe of a hydraulic

dredge. Mechanically dredged sediments such as with a clam shell will have

sediment pore water that will initially be dark in color and reduced. As

effluent water passes across the confined disposal site and approaches the l I

,*: discharge weir, the water becomes oxygenated ano will usually become light ..-.

. gray or yellowish light brown. The color change indicates further oxidation

of iron complexes in the suspended particulates as they move across the site.

* Once disposal operations are completed, dredged material densification and

consolidation will force pore water up and out of the dredged material and it

,* will drain toward the discharge weir. This drainage water will continue to

*" become oxidized and lighter in color.

165

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WIND

TURBULENT MIXING

AND OXYGENATION O SPERIC

SENTRAINMENT AND MIXING OXGAION

OF FINE PAHTICLES

'\ ~ -- ,,. / /-" "" "'MIXING _WIND "

k... ' - -SEDIMENTATION OF .",,.

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-'_'OSSOLVED FRACTION PLUS PARTICLES;::-:: I1..--

- "L----- Zt---'I -- . . ..- -._=. - _- • .--...-

.1 'ZC WATERFLU -

Figure 3. Schematic diagram of ponded water interaction in an•.

active confined disposal site "." .'

Once the surfaced pore water has been removed from the confinement, the

surface of the dredged material will become oxidized and lighter in color,-.-.

R! Vlsuch as changing from black to light gray. The dredged material will begin to

crack as it dries out. Accumulation of salts will develop on the surface of

the dredged material and especially on the edge of the cracks. Rainfall

events will tend to dissolve and remove these salt accumulations in surface

runoff.

Recent research on contaminant mobility from dredged material placed in

an upland disposal site indicates that certain metal contaminants can become

dissolved in surface runoff as dredged material dries out. During the drying

process organic complexes become oxidized and decomposed. Sulfide compounds

also become oxidized to sulfate salts. These chemical transformations could

release complexed contaminants to surface runoff, soil pore water, and leachate through the material. In addition, plants and animals that colonize the

upland site could take up and bioaccumulate these released contaminants.

Contaminant mobility will be significantly controlled by the physicochemical

changes that occur during drying and oxidation of the sediment.

Considerations for Con- 7

finement of Contaminated Material

Confined disposal of contaminated sediments must be planned to contain

dredged material within the site and restrict contaminant mobility out of the

site in order to control or minimize potential environmental impacts. There

are six possible pathways for transport of contaminants from confined disposal

sites:

166
a. Release of contaminants in the effluent during dredging operations.

b. Surface runoff of contaminants in either dissolved or suspended

particulate form following disposal.

c. Leaching into ground water.

d. Plant uptake directly from dredged material, followed by indirect

animal uptake from feeding on plants.

e. Animal uptake directly from dredged material.

f. Gaseous or volatile emissions during and after disposal.

*Options for Contaminant Controls

Depending upon the particular dredging operation, controls may be required for any or all of the contaminant pathways previously described. The

proposed management strategy (Figure 1) considers four options as available

for confinement of contaminated sediment with restrictions on contaminant

mobility. These options include:

a. Containment - dredged material and associated contaminants are

confined within the disposal site.

b. Treatment - dredged material is modified physically, chemically, or

biologically to reduce toxicity, mobility, etc.

c. Storage and rehandling - dredged material is held for a temporary

period at the site and later removed to another site for ultimate

disposal.

d. Reuse - dredged material is classified and beneficial uses are made

of reclaimed materials.

Obviously, combinations of the above options are available for a particular

dredging operation.

Containment of contaminated dredged material can be either In an existing

or a new facility. These facilities can be designed or modified to handle a

wide variety of contaminants. Most contaminated sediments can be disposed of

in an existing site where special controls have been incorporated. In the

case of highly contaminated sediments, a more secure disposal facility would

be required; and, in all probability, disposal restrictions would dictate the

design of a new facility.

The treatment option can be associated with either existing or new facilities. Some form of physical, chemical, or biological treatment would prob-

* ably be associated with the disposal of highly contaminated dredged material.

Treatment may also be combined with other options for disposal of slightly to

moderately contaminated dredged material in confined disposal sites.

Of the four available options, storage and rehandling can serve two beneficial functions: continued use of confined sites located close to dredging

areas and use as a rehandling facility for contaminated dredged material prior

to later disposal offsite.

167

* .....-. . . . . . .
Finally, the concept of a reuse option would incorporate beneficial uses

of materials reclaimed by the classification/separation process. Such mate- , 'I

rials could include sand and gravel or slightly contaminated construction fill

to be used for raising dikes or acceptable offsite uses.

Design Considerations

Contaminated dredged material management includes methods for dewatering,

transporting, storing, treating, and disposing of contaminated material. The

most technically and economically effective strategy to handle contaminated

dredged material will depend on many site-specific variables, which include the

following:

a. Method of dredging used--hydraulic vs. mechanical.

b. Method of dredged material transport--pipeline vs. truck or hopper or

barge.

c. Physical nature of removed material--consistency (solids/water

content) and grain-size distribution.

d. Volume of removed material.

e. Nature and degree of contamination; physical and chemical

characteristics of contaminants.

f. Proximity of acceptable treatment, storage, containment, or reuse

facilities.

g. Available land area for construction of new or expansion of existing

facilities.

Effluent Controls

Effluent controls at conventional confined disposal areas are generally

limited to chemical clarification. The clarification system is designed to

provide additional removal of suspended solids and associated adsorbed contaminants as described in Schroeder (12). Additional controls can be used to

remove fine particulates that will not settle or to remove soluble contaminants from the effluent. Examples of these technologies are filtration, adsorption, selective ion exchange, chemical oxidation, and biological treatment

processes. Beyond chemical clarification, only limited data exist for treatment of dredged material (4).

Runoff Controls

Runoff controls at conventional sites consist of measures to prevent the

erosion of contaminated dredged material and the dissolution and discharge of

oxidized contaminants from the surface. Control measures include maintaining

ponded conditions, planting vegetation to stabilize the surface, liming the

surface to prevent acidification and to reduce dissolution, covering the surface with synthetic geomembranes, and/or placing a lift of clean material to

cover the contaminated dredged material (4).

168

. *"

-. *. .. ... * ~.. .. *.* - -
Leachate Controls

Leachate controls consist of measures to minimize ground-water pollution

by preventing mobilization of soluble contaminants. Control measures include

proper site selection, dewatering to minimize leachate production, chemical

admixing to prevent or retard leaching, lining the bottom and sides to prevent

leakage and seepage, capping the surface to minimize infiltration and thereby

leachate production. vegetation to stabilize contaminants and to increase drying, and leachate collection, treatment, or recycling (4).

Control of Contaminant Uptake

Plant and animal contaminant uptake controls are measures to prevent

mobilization of contaminants into the food chain. Control measures include

selective vegetation to minimize contaminant uptake, liming or chemical treat- - J

ment to minimize or prevent release of contaminants from the material to the

plants, and capping with clean sediment or excavated material (4).

Other Controls

The control of gaseous emissions that might present human health hazards

can consist of physical measures such as covers, vertical barriers, control

trench vents, pipe vents, and gas-collection systems. Wind-erosion control of

contaminated surface materials is another type of management or operating control to minimize transport of contaminants offsite. Techniques for limiting

wind erosion are generally similar to those employed in dust control and

include physical, chemical, or vegetative stabilization of surface soils (13).

Summary

Conventional confined disposal methods, described previously, can be

modified to accommodate disposal of contaminated sediments in new, existing,

and reusable disposal areas. The design or modification of these areas must -

consider the problems associated with contaminants and their effects on conventional design. One control option, treatment, will play a vital role in

the handling and disposal of highly contaminated dredged material. Innovative

treatment concepts will need to be integrated with the overall plans for

dredging and dredged material disposal. Some of the more promising treatment

concepts will be presented in the following discussion.

TREATMENT METHODS

Water Treatment

The water discharged from a confined disposal site will vary in quantity

and quality over time and its characteristics will depend on the contaminants

included and the type of site controls and pre-treatment applied. Site efflu- -

ent will be produced in large quantities for hydraulically dredged sediments .-..

during the dredging process. This effluent will usually be of lower contaminant concentration than that found in the interstitial water and will almost

always be of lower contaminant concentration than that of future water discharges from the site. Runoff water will be produced during site dewatering

and periods of precipitation on the site. Runoff will be of concern primarily

during the dewatering and prior to placement of a surface cap on the site.

169

. . . . . mesh . . . . &adds ". 
" Runoff water may be of higher contaminant concentration than the original site

*effluent. Leachate water is produced as water moves through the sediments and

out the sides and bottom of a disposal site. This water is produced in the

smallest quantities but may contain relatively high contaminant concentrations

and may persist for a long period of time. Leachate treatment usually requires collection via drains placed under the site or wells for dewatering the

dredged sediments.

There are a variety of physical, chemical, and biological processes that

have been developed for municipal and industrial water and waste treatment

requirements. The major processes may be categorized according to their

intended function, capabilities, and limitations (Table 1). Many of these

processes have potential in treating contaminated dredged material discharged

confined upland disposal sites. However, few processes have actually been "at 

required for or applied to dredged material disposal. Among the processes

widely applied in confined disposal are plain sedimentation for solids and

sediment-bound contaminant removal, and chemical clarification and filtration

for enhanced removal of particulates (suspended solids), sorbed metals, and

organics. Use of activated carbon for removal of soluble organics has received some limited application to dredged material. Other processes not previously applied to dredged material include organics oxidation, dissolved

solids removal methods, and volatiles stripping.

Table 2 lists various water treatment processes having potential for

application and indicates which of these have been applied to dredged material

disposal. These treatment processes can be grouped into various levels of

treatment, depending upon a particular phase or class of contaminant being

removed. Four levels of treatment have been identified and are defined as

follows:

a. Level I is the removal of solids and particulate-bound contaminants.

b. Level II is additional treatment to remove soluble metals.

C. Level III is further processing to remove soluble organics.

d. Level IV is the highest degree of water treatment by dissolved solids

removal.

The relationships between levels of treatment are illustrated in Figure 4. A

comparison of the relative efficiencies of the treatment levels is given in

Table 3. Increasing levels of treatment result in increasing percentages of

contaminant remcval. The qualitative ranges of concentrations remaining after

each treatment level and percent removals are based on actual monitoring of

disposal sites for Levels I and II (where applicable) and on best available

water treatment technology for levels III and IV. It should be noted that the

estimates made for soluble organics and soluble metals removals past Level I

are mean values and represent a grouping of contaminants with large ranges of

solubility and treatability. The data in Table 3 should be reviewed as preliminary for planning purposes only, and, as such, are presented to illustrate

potential levels of removals. Actual removal efficiency data on dredged materials would have to be obtained through site-specific testing, evaluations,

and demonstrations. The Waterways Experiment Station will be evaluating various water treatment concepts over the next few years as part of several

ongoing and proposed field demonstrations.

170
4k-~~-°° k"k_ 1 K k

II

TABLE 1. TREATMENT PROCESS CATEGORIES AND APPLICABILITY

Category of ,..

Treatment Unit Process Capabilities Limitations

Physical Organic Phase Removal of organics Can only remove compounds A

Separation present at greater to their solubility limit

than their solubility in water, presence of a

limit in water, variety of compounds may

either settling or create organic plus water -

flotation mixtures which will not

float or settle

Solids Removal of suspended Generally rather low susSettling solids that are more pended solids levels in

dense than water and ground water, not too

therefore settle significant

Solids Removal of suspended Can only remove suspended

Filtration solids by entrapment, matter, backwash requiresolids that do not ments create another waste

readily settle stream to handle

Chemical or pH Adjustment Neutralizes excess H+ Simply neutralizes excess

Physical/ of OH present, can acid or alkali, removes

Chemical aid performance of nothing

other processes that

are pH dependent

Chemical Improved removal of Suspended solids generally

Coagulation suspended solids that are not too significant,

are difficult to only a precursor to

settle settling or filtration

Carbon Removal of adsorbable Suitable only for carbon

Adsorption dissolved organics adsorbable organics, many

low molecular weight

organics such as alcohols

and others are poorly

adsorbed, spent carbon must

be regenerated or disposed

Air Stripping Removal of volatile Suitable only for low boildissolved organics ing point organics (less

than water) with limited

solubility, creates an offgas contamination problem

which may require treatment

Steam Removal of volatile Some of the same limitaStripping dissolved organics tions as air stripping,

creates condensate stream

requiring disposal

(Continued)

171

7... . -.-.-
'4L~~~:~ ,%: K-- V

TABLE 1. (Concluded)

Category of

Treatment Unit Process Capabilities Limitations

Resin Removal of absorbable Suitable only for specific

Absorption dissolved organics compounds absorbable on the

resin, solvents may attack

resin, creates a regenerant

stream requiring disposal

Biological Aerobic Removal of biodegrad- Suitable only for biodeTreatment Suspended able dissolved gradable organics, many -

Growth organics volatile, relatively insoluble chlorinated solvents

are not amenable to biodegradation, creates biological sludge requiring

disposal

Aerobic Removal of biode- Same limitations as susFixed Film gradable dissolved pended growth systems, not

organics as susceptible to sludge

settleability upsets found

with suspended growth

systems

Anaerobic Removal of biode- Suitable only for anaerobigradable dissolved cally biodegradable organorganics ics, generally more limited

than aerobic oxidation,

produces CH which may be 4 usable as a resource

Residuals Sludge Provides sludge suit- Only a supporting operation

Treatment Digestion/ able for disposal to try to minimize cost of

or Sup Thickening/ residuals disposal -'

porting Dewatering

Processes Chemical Possible reprocessing Mixtures of solvents are

Recovery/ of solvents for reuse difficult to recover, can

Reuse offset some treatment

costs

Incineration Ultimate disposal of Generally suitable only for

either sludge or concentrated waste streams

residual organics (e.g., solvents or dewa- 1

tered sludges), generates

an ash for disposal .\-

172

. . .. . . . . . . . . . . . . . *'.*

. . . . . . . . . . . . .. . . . . . . . . . . .. . .. . . . ". -
'. '*a

TABLE 2. LISTING OF WATER TREATMENT PROCESSES

Applied to Not Applied

Proven Proven But Not Dredged to Dredged

Treatment Process Method Demonstrated Material Material

Suspended Solids

Plain Sedimentation X X '7

Chemical Clarification X X

Filtration X X

Soluble Metals

Precipitation X *

Soluble Organics

Adsorption X X

Ozonation X X

Dissolved Solids

Distillation X X

Reverse Osmosis X X X

Electrodialysis X X

Ion Exchange X X

Volatiles

Stripping X X

* Leachate**

Biological X X

Physical/Chemical * X X

• Limited success on pilot scale. , . '.

•* Potential for use of existing municipal or industrial process for

treatment offsite.

Immobilization Technology

Overview of Available Technology

Immobilization technology as applied to dredged material uses physical

* and chemical processes to produce chemically stable solids with improved contaminant containment and handling characteristics (Figure 5). These techniques are commonly applied to bottom sediments in Japan, where filling to

improve or develop land is desirable. Reports of the results of the Japanese

experience with stabilization have been presented in previous U.S./Japan

Expert Meetings and are documented in various proceedings entitled "Management

of Bottom Sediments Containing Toxic Substances." The primary thrust of the

Japanese research has been the improvement of handling and bearing capacities

of the sediments, with minor emphasis on efficiency of immobilization of contaminants. In the US practice, these immobilization techniques are used

almost exclusively in oil and gas drilling operations and on wastes from power

* plants, chemical manufacturing, and the nuclear industry. A recent review of

- 33 cases of contaminated sediments remediation in the United States (11)

173
LEVL I LEVEL 11 LVL I EVLI

LEE I LEE II LVLI

DREDGE PLAIN II INFLUENT 4'SEDIMENIATIONI I I I

CLARIFICATIONI

PEIIAINDIASTIATFLUON

OZONATION

IION

Figure 4. Treatment processes flow diagram

TABLE 3. CONTAMINANT REMOVAL EFFICIENCY OF TREATMENT LEVELS

Class of Percent Concentration

*Level Contaminant Removal Remaining

ISolids 99.9+ mg/i

Metals 80 to 99+ ppb to ppm range*

Organics 50 to 90+ ppb to ppm range*

II Metals 99+ ppb range*

Organics 50 to 90 ppb to ppm range*

TTII Metals 99+ ppb range**

Organics 95+ ppb range**

IV Metals 99+ Highest quality attainable** 1

Organics 99+ Highest quality attainable** -

*Concentrations based on Hoeppel et al. (5), and Palermo (9).

** Concentrations based on capability of best available treatment technology.

174 .
STABILIZATION

* TREATMENT - EX pH ADJUSTMENT CHEMICAL " TO REDUCE OXIDATION OR REDUCTION -%" i

SOLUBILITY ,

'..-

SOLIDIFICATION

SORBTION TO - EX. MIXING WITH FLY ASH

PRODUCE A OR CLAY SOLVENTS

SOLID WITH ,-. NO FREE LIQUID "

FORMATION OF ,5"t MONOLITH WITH K$7/77/k Z'i - EX. ADDITION OF PORTLAND CEMENT (MAY BE ADDED ALONG WITH SORBENTS)

,REDUCE

SURFACE

Figure 5. Steps in immobilization of wastes

revealed only two cases, the Upper Hudson River in New York and Waukegan Harbor in Illinois, where stabilization was among the remediation techniques

evaluated, but no cases of actual use were identified.

The immobilization techniques, stabilization and solidification, have two

different goals. Stabilization systems attempt to reduce the solubility or

chemical reactivity of a waste. Solidification systems attempt to convert the

waste into an easily handleable solid with reduced hazard from leaching or

spillage. Because both processes have the common purpose of improving containment (immobilization) of potential contaminants in treated dredged mate-

,- rial, they will be discussed together.

Most immobilization systems being marketed in the United States are proprietary processes involving the addition of absorbents and solidifying agents

to a waste. Often the marketed process is changed to accommodate specific

wastes. Comprehensive general discussions of waste stabilization/

solidification are given in Environmental Laboratory (1), Malone and

-* Jones (7), and Iadevaia and Kitchens (6).

Waste immobilization systems that have potentially useful application in

confined disposal activities are:

175

- .. -- * . *.* -
a. Sorbtion.

b. Lime-flyash pozzolan processes.

c. Pozzolan-portland cement processes. F

Other technologies such as thermoplastic microencapsulation, macroencapsula- K.

tion, and fusing waste to a vitreous mass or using self-cementing material are

too specialized or not sufficiently field applicable to be used at

present (1).

Sorbtion. In order to prevent the loss of contaminated fluids and improve the handling characteristics of the sediment, a dry, solid absorbent may

be added to the dredged material. The sorbent may interact chemically or may

be wetted by the water part of the dredged material and retain the liquid as

part of the capillary liquid (Figure 6). -

The most common sorbents used with waste include soil and waste products

such as bottom ash, fly ash, or kiln dust from cement manufacture. In

general, selection of sorbent material involves trade-offs between chemical

effects, costs, and amounts required to produce a solid product suitable for

burial.

Artificial materials have also been advocated for use as sorbents in

solidification; however, the relatively high costs of these materials have

limited their use. Synthetic materials have generally found use where binding

of a specific contaminant in the waste is of paramount importance. Table 4

lists various synthetic sorbent materials that have been developed or tested

for use with hazardous waste.

When selecting a sorbent it is important to note the following technical ,... considerations: -..

a. Quantity needed to eliminate contaminated drainage fluid.

b. Compatibility or reactivity of the contaminants and the sorbent.

c. Level and character of contamination that might be introduced in the

sorbent.

d. Chemical binding properties of sorbent for specific contaminants.

Sorption has been widely used to eliminate free liquids and improve

handling. Some sorbents have been used to limit the escape of volatile

organic compounds. Sorbents may also be useful in contaminant immobilization

when they modify the chemical environment and maintain the pH and redox poten-

. tial to limit the solubility of the contaminants. Sorbents are widely used in

lined landfills in the United States to eliminate or control the pressure head

. on the liner, but the liner is the major protection for the surrounding envir-

" onment. Caution must be exercised to ensure that leachable contaminants are

. not introduced as by-products of the sorbent itself.

Lime-flyash pozzolan processes. Solidification/stabilization of dredged

material using lime and pozzolanic materials requires that the material be

mixed with a carefully selected, reactive flyash (or other pozzolanic

"" material) to a pasty consistency. Lime (calcium hydroxide) is blended into

176

• . . -. .

.,;....... . . . . . .'" : ." - " '" "w ' " "."". " " . - . . ' " , " . '. 

o

*" ". '. ' - . . . • . . .7. '. . . .' . " °" " . " " . ." " . .. • • - . - . " ",
NEW CONTAINMENT SYSTEMS

AdsortionAdsorbed species

Example: Interaction of single layer of clay mineral AN

with polar groups Adsrb ntClay

Chemsorption

Example: Organic compounds on clays

*Polar molecules with Polar and nonpolar Polar molecules

*montmorillonite molecules with with halloysite

montmorillonite

Reaction rind

or of BaSO

Passivation ~B%

Example: Reaction of gypsum with barium ~ Be+ -(SO 4 2H 20

C

Diadochy ea2+ orM+2

Example: Substitution in the calcite Fe- Mn etc. crystal lattice FeMntc

3

Reprecipitation

Example: Production of sideronatrite from sodium sulfate

e2(S04)3 2a 2SO 4+ 20

2N a2Fe(S0 4)2 *3H 20 + H20 + H2S04

Comparative Solubilities at 250 C

Na SO * 7H 0 524 g/k 2 4 2

Na FeS *3-0.16/ 2 eS 4)2 3 20 O.g/

Figure 6. Mechanisms retaining water on and in solid phases t

177
- 77 7 I7

TABLE 4. SYNTHETIC SORBENTS USED WITH HAZARDOUS WASTES

I,

Sorbent Waste Treated Effectively

Activated Alumina Sorbs fluoride in neutral wastes

Activated Carbon Sorbs dissolved organics

Hazorb* Sorbs water and organics

Locksorb** Reported effective with oil emulsions

Imbiber Beadst Reported useful in spills of inert

spirits-type liquids (cyclohexane)

Product of Diamond Shamrock Corp.

• * Product of Radecca Corp., Austin, Tex.

t Product of Dow Chemical Co., Midland, Mich.

the sediment-flyash mixture. Typically 20-30% lime is needed to produce a

strong pozzolan. The moist soil-like material is then placed in the confinement and roller compacted.

In general, flyash-lime solidified materials are not as durable as

pozzolan-portland cement composites. Common problems with lime-pozzolan reactions relate to interference in cementitious reaction that prevents bonding of

materials. The bonds in pozzolan reactions depend on the formation of calcium

silicate and aluminate hydrates. Several materials to include sodium borate,

calcium sulfate, and carbohydrates can interfere with this reaction. Oils and

greases can also physically interfere with bonding by coating soil particles.

The cementing system is strongly alkaline and can react with certain contaminants to release undesirable materials as gas or in leachates.

Pozzolan-portland cement processes. There are a variety of treatment

processes that incorporate portland cement as a binding agent. Pozzolanic

products (materials with fine-grained, non-crystalline, reactive silica) are -

frequently added to portland cement to react with any free calcium hydroxide

and thus improve the strength and chemical resistance of the concrete-like

product.

Waste solidifying formulations based on portland and pozzolan-portland

systems vary widely and a variety of materials have been added to alter performance characteristics. Such materials include soluble silicates (3),

hydrated silica gels, and clays such as betonite, illite, or attapulgite.

Cement-based immobilization systems have proved to be highly versatile

and flexible methods. The composite materials can be found to have exceptional strength, excellent durability and retain contaminants very effectively. However, these systems have limitations that relate to the effects of

the contaminants on the setting (retardation from calcium sulfate, borates,

carbohydrates, etc.) and stability of the silicate and aluminates that form

178
VVL 1. 'Cl LI Vq AMNO

when the portland cement hydrates. The very high alkalinity of hydrating

portland cement can cause the evolution of ammonia gas if ammonium ion is

present in abundance in the material and the solubilization of some metals

(e.g. nickel, lead, zinc) at high pH's.

Compatibility of Contaminants and Treatment Process

The chemical reactivity of the waste component generally controls the

selection of immobilization options and its optimization. Table 5 summarizes

*. the major chemical considerations that direct the selection of a particular

*-" immobilization system. Most solidification systems will work under adverse '

circumstances if adaptions are made in the material being treated or the processing train.

Implementation Strategies

Onsite immobilization programs can be classified according to the manner

in which the chemical reagents are added to and mixed with the materials being

treated. Three basic onsite implementation strategies are considered applicable to confined disposal: in situ mixing, plant mixing, and area mixing.

The selection of an appropriate implementation strategy must be based on

an analysis that applies site-specific factors to the attributes of the available strategies. As a result, definitive guideiines for implementation strategy selection based on generalized criteria cannot be developed. However, it

is possible to develop some generalized attributes of each strategy as applied

to conditions expected at confined disposal sites.

In situ mixing. This method is primarily suitable for dredged slurries

that have been initially dewatered. In situ mixing is most applicable for the

addition of large volumes of low reactivity solid chemicals. This strategy

incorporates the use of construction machinery, typically a backhoe, to accomplish the mixing process. Where large containment areas are being treated,

clamshells and/or draglines may be used. Data are not currently available on

the mixing efficiency of the in situ process when applied to large field-scale

projects.

Major modifications to the in situ mixing strategy include the development of the reagent addition and mixing equipment that allows better control

of the process. Equipment specifically designed for in situ stabilization is

currently being developed and evaluated (ENRECO 1983, American Resources Corp.

1984). Each system is estimated to provide in situ stabilization of up to

iOOO cu yd of sediment per 8-hr working day. The ENRECO equipment is limited

to an operating depth of approximately 4 ft. Shallower depths result in blow

out or additive communication to the surface. With the American Resources

Corp. PF-5 Pond Injection System, depths of up to 11 ft can be treated.

Plant mixing. Plant mixing strategies can be adapted for applications to

slurries and solids. Plant mixing is most suitable for application at sites

with relatively large quantities of contaminated materials to be treated. In

the plant mixing process the materials are physically removed from their location, mechanically mixed with the immobilization reagents, and redeposited in

179

.......................................... . . -.
TABLE 5. COMPATIBILITY OF SELECTED WASTE CATEGORIES WITH

DIFFERENT STABILIZATION/SOLIDIFICATION TECHNIQUES

Treatment Type

Waste Component Cement-Based Pozzolan-Based

Organics

Organic solvents Many impede setting, Many impede setting,

and oils may escape as vapor may escape as vapor

Solid organics Good--often increases Good--often increases

(e.g., plastics durability durability

resins, tars)

Inorganics

Acid wastes Cement will neutralize Compatible

acids

Oxidizers Compatible Compatible

Sulfates May retard setting and Compatible

cause spalling unless

special cement is used

. Halides Easily leached from May retard set, most

cement, may retard are easily leached

setting

Heavy metals Compatible Compatible .? -

Radioactive Compatible Compatible

materials

After Environmental Laboratory (1). b

a prepared disposal site. Special equipment adaptations have been utilized to

handle sludges with high solids contents and contaminated soils. A schematic

diagram of a typical plant mixing strategy is illustrated in Figure 7.

Area mixing. This strategy is applicable to those confined disposal

sites where high solids content slurries must be treated. The term "area

mixing" is used to denote those strategies that use horizontal construction

techniques to add and mix the stabilization reagents with the dredged mate- .-.

rial. Area mixing is land area intensive, requiring a relatively large land

area to carry out the process. Area mixing strategies present the greatest

possibility for fugitive dust, organic vapor, and odor generation. The typical area mixing strategy will require that the dredged material be sufficiently dewatered to support construction equipment.

180

. . . . . .* . . . . . . . * . . .- . . . . . . - . - - - - - - - -
,..i *%.

BULK

IIDuu BULK

ORAGE SOLIDS "- , STORAGE

WASTE HOLDING

AREA

LIQUID CHEMICAL ''""

FEED PUMP""'"

WASTE

FEED TO DISPOSAL

PUMP MIXER OR CURING

AREA

Figure 7. Schematic of plant mixing scenario

The three basic implementation strategies can be incorporated into confined disposal operations in a variety of ways to improve contaminant containment. In most cases, the same immobilization reagents and equipment could be

employed.

Application of Immobilization

Technology at Confined Disposal Sites

Immobilization technoiogy can potentially be used in a variety of ways to

treat contaminated dredged material to provide improved management and disposal operations (Figure 8). The concepts presented in Figure 8 can be incorporated into the overall management and disposal operation beginning with the -,,*.

project planning stage.

Concept "A" " " "

As shown in Figure 8, Concept "A" involves alternating layers (thin

lifts) of relatively clean dredged material and contaminated dredged material

that is stabilized. The initial lift of clean, fine-grained sediments would

be dewatered to promote densification and consolidation to provide a low permeable soil layer or natural liner for the containment area. Once this layer

has achieved the desired degree of consolidation and permeability, the contaminated material would be placed on top, dewate-ed, and stabilized in situ.

(Various schemes for in situ stabilization have been discussed previously.)

This layering process would continue until the containment area was filled. A

final soil cover would be added, shaped, and vegetated.

Concept "B"

The second disposal method shown in Figure 8 incorporates soil stabilization as a treatment to produce a low permeable liner and is designated Concept

"B." The stabilized soil layer is used to contain any leachate generated from

the dewatering and long-term disposal of the contaminated dredged material.

181

.. . .. . .. .. ............. ,,, . .
FIA CO E LAYER".- ~ ~ ~- -- ..

LAYE MATRIA OF TABLIZE 

a. DISPOSAL CONCEPT "A" ALTERNATING LAYERS OF STABILIZED MATERIAL

b. DISPOSAL CONCEPT "B" STABILIZATION FOR LINER SYSTEM

* c. DISPOSAL CONCEPT "C" STABILIZATION IN SECURE FACILITY

Figure 8. Immobilization concepts for

confined disposal operations

182
F Appropriate chemical reagents are added and mixed with the disposal site soil

* using either the in situ or area mixing methods. Then a layer of coarse mate- -"

rial is added above the stabilized layer to facilitate dewatering and collection of leachate. The contaminated dredged material is disposed next and

dewatered. A clean layer of dredged material is used as final cover. One

modification to this concept would be the additional step of stabilizing the

* contaminated dredged material to further protect against contaminant escape.

*Concept "C"

The final concept illustrated in Figure 8 is Concept "C." This disposal

*: method provides the highest degree of environmental prc.-ettion. A soil liner,

or flexible membrane, or both, are used to line the bottom and sides of the

disposal site. Then a coarse-grained layer is used to facilitate dewatering

and leachate collection. The contaminated sediment is disposed into the lined

site, dewatered, and stabilized. An alternative would be first to dewater the

contaminated sediments in a temporary processing facility, and then to apply

- the stabilization process prior to placement of the treated material in the

*" confined disposal site. This stabilization operation would be accomplished

using the plant mixing strategy (either mobile or field erected) or the areawide mixing strategy, stockpiling the stabilized material prior to rehandling,

and disposal in the prepared site. The last operation in Concept "C" would be

to final cover, shape, and vegetate the site.

Summary

- The treatment methods identified as having potential for application to

confined disposal of contaminated dredged material can be grouped into water

treatment processes and immobilization technologies. Four levels of water

treatment were identified with increasing efficiencies for contaminant re- - movals. It should be remembered, however, that the relative degrees of contaminant removals past treatment level II are estimated, and, as such, are

useful for preliminary planning purposes only. Final processing trains will

be identifiable only on a site-specific basis because of the individual testing and evaluation studies required to develop -he detailed design and operation parameters.

Three immobilization systems were identified as having useful application

in confined disposal operations: sorbtion, lime-flyash pozzolan processes,

and Pozzolan-portland cement systems. Various modifications to the basic systems exist and process applicability is evaluated on a case-by-case basis.

Compatibility of the contaminants in the dredged material and the immobilization process will play a key role in the selection of a particular process or

system. Strategies for implementing the immobilization processes were grouped

according to the manner in which the rhemical reagents are added to and mixed

with the materials being treated. Three strategies (in situ mixing, plant

*. mixing, and area-wide mixing) were presented and discussed as being applicable

to confined disposal operation.

Finally, three confined disposal concepts that incorporate some form of

immobilization technology were conceptually presented. These concepts were

designated "A," "B," and "C." The feasibility of applying the various treatment concepts presented in this paper at an existing or new confined disposal . .

site will be established under an ongoing U. S. Army Corps of Engineers

183

• .[.. * ."*-. *.*
\:.b ..

project demonstration at Indiana Harbor, Illinois. The potential for extending this evaluation to the "Commencement Bay Washington, Superfund Study" also

exists.

COMMENTS

*- The treatment concepts identified as part of this paper and presented at

the 10th U. S./Japan Experts Meeting on "Management of Bottom Sediments Containing Toxic Substances," are based on a requirement to incorporate proven

technology with existing U. S. Army Corps of Engineers confined disposal

operations. The emphasis necessarily is therefore on an adaptation of exist- -.--

ing treatment methods developed for treatment of waste liquids and solids.

The treatment of extremely contaminated toxic sediments to include chemical

spills clean-up is not addressed as part of this paper. Research on the

handling and clean-up of chemical spills is sponsored by the U. S. Environmental Protection Agency (EPA). Our research programs are, however, closely

coordinated with the EPA's in order to derive mutually beneficial program

technology exchanges.

REFERENCES

1. Environmental Laboratory. 1980. "Guide to the Disposal of Chemically

Stabilized and Solidified Waste," SW-872, US Environmental Protection

Agency, Washington, DC, 126 pp.

2. Environmental Laboratory. 1983. "Management Strategy for Disposal of

Dredged Material," US Army Engineer Waterways Experiment Station,

Vicksburg, Miss.

3. Falcone, J. S., Jr., Spencer, R. W., and Reifsnyder, R. H. 1983. "Chemical Interactions of Soluble Silicates in the Management of Hazardous

Wastes," Draft Report, The PQ Corp., Lafayette Hill, Pa.

4. Gambrell, R. P., Khalid, R. A., and Patrick, W. H. 1978. "Disposal

Alternatives for Contaminated Dredged Material as a Management Tool to

Minimize Adverse Environmental Effects," Technical Report DS-78-8,

US Army Engineer Waterways Experiment Station, Vicksburg, Miss.

5. Hoeppel, R. E., Myers, T. E., and Engler, R. M. 1978. "Physical and

Chemical Characterization of Dredged Material Influents and Effluents in

Confined Land Disposal Areas," Technical Report D-78-24, US Army Engineer

Waterways Experiment Station, Vicksburg, Miss.

6. Iadevaia, Rosa, and Kitchens, J. F. 1980. "Engineering and Development

Support of General Decon Technology for the DARCOM Installation Restoration Program," Task 4, Draft Report, Atlantic Research Corp., Alexandria, -:

Va., 77 pp.

7. Malone, P. G., and Jones, L. W. 1979. "Survey of Solidification/

Stabilization Technology for Hazardous Industrial Wastes," EPA-600/2-79-

056, US Environmental Protection Agency, Cincinnati, Ohio, 41 pp.

184 :

. . . . . . . - - . , . . . .. * . . * * . *~* . . . . * . .
8. Montgomery, R. L., Thackston, E. L., and Parker, F. L. 1983. "Dredged

Material Sedimentation Basin Design," Journal of Environmental Engineering, American Society of Civil Engineers, Vol 109, No. 2.

9. Palermo, M. R. 1984. "Interim Guidance for Predicting the Quality of

Effluent Discharged from Confined Dredged Material Disposal Areas," Draft

Engineer Technical Letter, Office, Chief of Engineers, Washington, DC. ,-

10. Palermo, M. R., Montgomery, R. L., and Poindexter, M. E. 1978. "Guidelines for Designing, Operating, and Managing Dredged Material Containment

Areas," Technical Report DS-78-10, US Army Engineer Waterways Experiment

Station, Vicksburg, Miss.

11. JRB Associates. 1984. "Removal and Mitigation of Sediments Contaminated

with Hazardous Substances," Draft Report, Municipal Environmental Research Laboratory, Office of Research and Development, US Environmental

Protection Agency, Cincinnati, Ohio.

12. Schroeder, P. R. 1983. "Chemical Clarification Methods for Confined

Dredged Material Disposal," Technical Report D-83-2, US Army Engineer

Waterways Experiment Station, Vicksburg, Miss.

13. US Environmental Protection Agency. 1982. "Handbook for Remedial Action

at Waste Disposal Sites," EPA-625/6-82-006, US Environmental Protection

Agency, Cincinnati, Ohio, 497 pp.

* o-. - ".'

185

'.....'.

-.-. * ( < .f.. 
THE INFLUENCE OF ACCUMULATING ORGANIC SEDIMENT

ON THE MARINE ENVIRONMENT IN OSAKA BAY

M. Kawaguchi, T. Saski, H. Noguchi

The 3rd District Port Construction Bureau

Ministry of Transport, Japan

INTRODUCT ION

The coastal area along Osaka Bay is a densely populated region with

12,920,000 people living in approximately 4,800 kin Water quality in Osaka

Bay has been deteriorating due to an inflow of contaminants discharged from

industrial sites along the coast since the rapid economic growth period of the

1960s. Particularly, in the offshore bay area (bay head) where the tidal flow

is stagnant, eutrophic pollution is progressing. The accumulating organic

sediments which release phosphorus and nitrogen are accelerating the eutrophication of the water. Since 1979, a variety of investigations have been conducted by the 3rd District Port Construction Bureau of the Ministry of Transport to probe measures for improving the offshore sea environment. This

report presents our study of the influence of the accumulating sediments on

. the sea environment and on its clarification plans.

PRESENT CONDITIONS OF WATER POLLUTION IN OSAKA BAY

The deteriorating seawater environment in Osaka Bay is creating problems

such as the occurrences of red tide and the appearance of anaerobic water

masses. In 1973, the Special Law for Conservation of the Environment of the '

Seto Inland Sea was enacted, followed by various efforts to enhance the regu- -

latory system such as the enforcement of the Areawide Total Pollution Load

Control Concerning COD (Gross COD Control). However, despite the regulation

of inflowing loads of COD, no significant improvement in water quality has

been attained as was initially expected, leaving water quality in the same

state as several years ago (Figure 1, Table 1).

Figure 2 shows the levels satisfying the environmental standards at the

standard stations in Osaka Bay in 1982. Of 21 monitoring stations, 14 did not

meet the standards.

Moreover, as seen in Table 2, the incidence of red tide is still high,

totaling 20 in 1983.

DETERIORATION OF MARINE ENVIRONMENT DUE TO ORGANIC SEDIMENT

Realities of Population in Bottom Sediments

As indexes for the pollution level of the Osaka Bay sediments, COD,

ignition loss, sulfide, total phosphorus, and total nitrogen were chosen and

investigated. Figure 3 displays the horizontal distribution of the index

substances in the bottom sediments (the uppermost 0- to 5-cm layer). The

investigation revealed that, in the offshore bay area, COD was not less than

186

............. ,
mrg/ e

4.~

X V -' G W1 Wl

Cfl U2 U2... 3- O-JIIl l

2

*0 LL Y

1972 1973 1974 1975 1976 j(977 1978 1979 1980 1981 1982 Example

Year o

Figure 1 Yearly course of COD change in Osaka Bay (annual mean

at the monitoring stations for environmental standard).

Prepared from: White Paper on Pollution (Osaka Prefecture)

and White Paper on Environment (Hygo Prefecture)

TABLE 1. YEARLY COURSE OF THE CHANGE OF NUMBERS OF DISQUALIFIED AREAS

BY COD ENVIRONMENTAL STANDARD IN OSAKA BAY

--- , ea r 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982

Sea Area--

C (5 points) 0 0 0 0 0 (0 0 0 0 0 0

B (5 points) 1 3 5 i 5 4 5 5 5 3 5

A (ll points) 1 6 8 8 9 9 8 9 9 6 9

Tot~l!)I'

( 2 poicts) 10 9 1 3 1 :3 14 1 3 13 1 4 1 4 9 1 4

(Number)

TABLE 2. NUMBER OF OCCURRENCES OF RED TIDE IN OSAKA BAY

Year 1971 pi7211973 t974 1975 1976 1977 1978 1979 1980 I 8 1982 1983 . .... ...---. . --- F -- /- I- . .... . ... 1 .. -7. .

Osaka Bay 2 29 39 5 0 4 9 5 4 314 38 3 . 8 42 3 8 3 1 41)

From: Red Tide in Seto Inland Sea Compiled by Setonaikal

Fishery Adjustment Office, Fishery Agency

187

*"" , .i - - ,-. ' - " .- " , ,' - ' . " ' ' ' - - . - o " - . . . .- - ' ' '" 
.. ,. . -. . * .. - "P"W"- 1 7-7 ;- Z-1-- .-

! 982 , !

/) COoAXA A

AKASHI AX I

0 : Site whnere the envirtrvra1 C: 8 mgi max.

stardard is satisfied.B:3 g/ a."2- "

* : Site whr the vliwm-etal B gimx

stalr is not satisfied. A: 2 mg/i max. i '

30 mg/g, sulfide not less than 0.6 mg/g, ignition loss not less than 10 per- '

C3

cent, T-N 2.0 mg/g or more, and T-P 0.65 mg/g or more.

Core samples were taken from the botton sediments by using a box corer ":-'

(sediment core sampling device) for an assay to obtain the thickness of the,:-- layers of the bottom sediments. The results of the assay (Figure 4) show that

the bottom sediments with COD > 30 mg/g ignition loss > 0 percent and

sulfide > 0.6 mg/g tend to increase in thickness in the offshore bay area.

However, the accumulated sediments are relatively thin, with the maximum

thickness being 40-50 cm. vel of ct

Correspondence of the Areas of Polluted Sea Bottom

Sediments and the Areas Where the Quality of the not l

Bottom Water Layer is Aggravated 0

Realities of Pollution in the Bottom Layer of Water

As indexes for aggravating water quality at the bottom layer, dissolved

oxygen (DO) in water, ammonium nitrogen (NH4-N), and inorganic phosphorus .':

(PO4-P) were chosen and determined for their distribution in Osaka Bay --... (Figure 5). t i-ut a-h

The investigation showed that the distribution of areas where quality of

the bottom water layer deteriorated corresponded to that of the areas shown in

188 i i s g i t e t y s

oxygen~~~~~~~ moimntoe.N4Nadiogncpopou ~ ~ ~ ~ ~ ~ ~ (DO inwtr 

(P04P) wre hose fo thir anddetrmind dstriutin inOsak°Ba
C oD Ignition loss (IL)

- ! AKA AKAS " "'"".

.... -' '"

KISHIjAlA .KISSZAADA

AH= 30f/ max,. SENNA 10 0

oriax.

0 I .30-40 

e AXAYAY.A

e• -4-i5 min

Sulfide

KU

,K (:sHWAZA

"->- . -,.= 06M91 ma..../

06- 0.8 - -.

~00,min.

70ral Phosphorus (T-?) 'Tocal uizrogen Cr-M)

AKASHI ( NKXjS$s

~rn.

Figure 3. Horizontal d.stribution of COD, sulfide, T-N, and T-P

in bottom sediments (0-5 cm)

189

. . . . . . . . . . .
COT) 30 /g Igini ion Joss ;10 %

KoeCty lg 4.0 X.'be Ciy >It 5

Kob.CitCyt

Island Island

Kishi.ada Kishi~ad,

city city

SeaCity X./~flCt

enn i " ty 0 .6 C ity

Sulfide 0.6 > mglgI

Kbe City -- eA C .C ot 

Citty .21p

A'aj i I0cm Island ~4c

K. hl. . dS o I3_.,. fC 

Sennan CityL..VmP

" Wooa.City

Figure 4. Distribution of the accumulated sediment thickness

Figure 3, i.e., where the bottom sediments were polluted. From the above

results, we may assume that the accumulated organic sediments deteriorate

water quality and constitute a factor of eutrophic pollution. Pollution is

particularly serious in the bottom layer of seawater in the offshore bay area .

where the DO level is 5 mg/g or less and phosphoric acid phosphorus is

0.02 mg/V or more.

Relationship Between the Quality of the Bottom Water

Layer and the Surface Layer of Bottom Sediments

As seen in Figures 3 and 5, the quality of the bottom water layer is

190

.- .go .

--.. -. o o..."-.---o..-,. . . . .. .- - .°.n -.. . . . . .. , 

' L. . -' .- "'_._ ""_ "-"._.-"._.""--,f,-_. ', "_ ._'''. .- " -"" ' " " "• "-" .. u' '..p a'-3a.. "

". --. ." - ".- -°- "- -- 

b- 

"•t.-
A-A±63 ?99 MANAGEMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC 3/5 SUBSTANCES: PROCEEDINGS 0 .(U) CORPS OF ENGINEERS FORT BELVOIR VA MATER RESOURCES SUPPORT CE. T R PATIN UNCLASSIFIED OCT 85 F/G 13/2 N

Ehmhmhhmh
1.0.

%~ L32 132 2

L3

MICROCOPY RESOLUTION TEST CHART

NATIONAL BUREAU OF STANDARDSI963-A
Dissolved oxygen (DO) Phosphoric acid phosphorus (PO% _P) Ii ORE Po,

AXum iroge ) e'. ' 

Y_/" '" _ e"USA,"K

AKASHI

/N ,

KISHIWADA KISHIWADA

D i' Min.

M3.0 - 4.0 002 0.04

VAKSAM 3 3.0 max. ~ 00.JCYAA )04 mi~n.

Ajmonium nitrogen (NH4 -N) V

. \,:AKAI

KISH!.ADA

A -I(- ,"FvV "t "max. .-

0. wi - 0.10

.aAY.AYA34A j o min.

Figure 5. Distributions of the concentration of DO, N, and P in the

water of the bottom layer

largely affected by the levels of pollution in the surface sediments. The

relationship between these two layers is shown in Figures 6-8 where the abscissa represents pollution index of the bottom water layers at each monitor-

* ing station, and the ordinate the pollution index of the bottom sediments.

When COD, sulfide, and IL in the bottom sediments are 30 mg/g and more,

0.6 mg/g and more, and 10 percent and more, respectively, the concentration of

DO in the bottom water layer tends to decrease, while the concentrations of

inorganic phosphorus (PO4 -P) and ammonium nitrogen (NH4-N) show marked

",* increase. This phenomenon is particularly remarkable in the shallow seawater

areas less than 20 m deep.

191

.. .- -.
10. 10

:8o 0 o

0 . 0

,.4W 0 * o4o %% Gbc

00% ,0t-. ;U !0.5 & 80

0 C 0

0 10 20 30 40 50 0 5 0 1i 2025

COD (mg/g) in the surface sediment IL (2) in the surface sediment

10r

0 ~ ~ 0 ,,-

a W.= 6

g . 0

ro

-;~~ - 4 [O ' f 01

0 1 0

Sulfide (mg/g) in the surface sediment

Example

Bottom layer of seawater :values measured in summer at 2 m above

the sea bottom V

Surface layer of the

bottom sediment: values measured in summer in the uppermost

0 - 5 cm layer

0 Depth of water<20 m

* Depth of water_20 m

Figure 6. Relationship between DO in the bottom layer of seawater ,.%-*

and surface layer of the bottom sediment A

192

*4*4NOLL
0

F--J

A0

A' 0 .0

o 0.10

0 0 0 0

4 0.08 0.08

S0 00 A 

0.06 0 0.060

41 cb toO

-- o Eo %" 0 0 %00 .04 -0 0

* 0.04 0 .00

'-p0

0. .JP

• . . ... . . . . .. . . . 0 10 20 30 40 50 0 0

COD (mg/g) in the surface sediment Sulfide (mg/g) in the surface ,. I. sediment A"•"

0 0

4'0 0

04 t 0 0 . 9 0.06

.t0) 0.0600

000 oO

0' 00.08o 0 

0 0 0 %

0 0.04- 0 004 00 0 0

10 10 0 c 0 ".-_ .

002 * A. -4.

00 5 I6 15 20 25 0 0.? 0.4 0.6 0.8 1.0

IL M% inthe surface sediment T-P (njr./g) in the

bottom sediments

Figure 7. Relationship between phosphoric acid phosphorus (P04-P)

and the surface layer of the bottom sediment

Release of Index Substances from the Bottom Sediments

In the distribution of the areas of the polluted bottom water layer, as

seen in the case of the polluted bottom sediments, the pollution is advanced

in the offshore bay area, suggesting a strong influence by the pollution in

the bottom sediments. Hence, the release rates of the index substances were

determined for their distribution in the bottom water layer by using the

193
Um

0g

0.50 a 050

" .2

"0.200 . 0.20 a

,, 0 0 0 0

00 0.10

0.20 0.100.0 ~0 0 . .6 _ 0 00;

M 0 0

0 10 20 30 40 so - 2

COD (rag/g) in the surface sediment Sulfide (rag/g) in the surface

sediment

U U "..-

0 0

0 0.40 0 0.40

" 0.30 0 .30

00.0

- '0 0.20 W 0.200

@44 0 00 40o 0 . 0 

0 "o 0 _ 

0 . ,- a, 0....0 ,-..-C.

0 1 5 15 0 250 0 1.0 2.0 3.0

L (%) in the surface sediment T-P (we,,1 ) in the sea bottom sLdiments

Bottom layet

of seawater: value& :,c;i;ured in summer at -.-

2 m above the sea bottom

Surface layer of the

bottom sediment: vallct. measured in summer

in the uppurt'ost 0 - 5 cm layer.

0 Depth of water20 m

* Depth of water20 m..

Figure 8. Relationship between ammonium nitrogen (NH4-N) in the

bottom layer of seawater and the surface sediments

194

i t, I
interior released load test device shown in Figure 9. The sediment cores were

obtained at each monitoring station from the 0- to 30-cm layer, the 50- to 80-

cm layer, and the 100- to 130-cm layer of the bottom sediments. The release

rate was calculated by Equation I using the values in the time course of the

concentrations of the released substances in the overlying water. (Note:

Hereafter, the released load of COD and the release rate of COD mean the

released load and the released rate of organic substances determined by COD,

respectively.)

m gas Siphon for

Isampling water

Overlying

Sample mud *

Interior test device r." -

for released load

(Note) The release rate means the released volume per day, and is obtained

from the gradient of the straight regression line relating the elapsed days

from the start of the test to the released volume calculated by equation (1) %

using the change of concentrations in the overlying water in the released

load test device.

n n

E v - rI i I Ci - C -l i -I i i.I

i S

Ni: Released load (mg/M2 ) from the start of the test to the ith sampling

day

Vo: Initial volume of the overlying water (t)

VI: Sampling volume for the ith day (1)

Ci: The concentration of released substances in the overlying water ,=

at the ith sampling (mg/t)

S: Surface area of the bottom sediment in the device (m2 )

Figure 9. Test device for released load

Figure 10 shows the release rates for COD, T-P, and T-N at 10 monitoring

stations at Osaka Bay. The release rates for COD, T-P, and T-N are all higher

in the areas of the polluted bottom sediment in the offshore bay area. Their

release rates are markedly lower in the 50- to 80-cm and 100- to 130-cm layers

from the sediment surface as compared with the values of the uppermost 0- to - .

30-cm layer. Therefore, it can be assumed that removal of the uppermost 50-cm

layer will lead to improvement of the water quality in Osaka Bay.

The comparisons between the release rates of T-P and inorganic phosphorus

(PO -P), and between those of T-N and ammonium nitrogen (NH4-N) at each monirortng station are shown in Figure It. The figure shows that the majority of

the released phosphorus is inorganic phosphorus (P04 -P), and that of the

* released nitrogen is ammonium nitrogen.

195

-. . . . . . . . - .* * * . . * ; . . * . . . * ' .*.•. ~ ~ 4 , I
AKASHI coMUAKSHI !A

IL A

J1 KSHWAI XISHtWAfl*

JIM;

* *

COD -

W.ASH!

5 10

" II KtSHtW.-A

Temp.: 25t

DO: At the first stage

st.1,st.jO-q0/1

Others ------- 5mg1

T-N (Unit: ng/m 2lday)

August 1981

Figure 10. The release rate of COD, T-P, and T-N from bottom sediments

196
Eum Example 25-

20- T-jfM

"Ca R 10-

~~~St.I S1.2 St.3 St.,I St.5 .ql.6 St.7 St.8 St.! St.10 ,, -,

140'

>-120 - Example,,...,

t I00J JfI-N T-N 

W. 60 *r

40

H- 20- f~

40 "" m 20 ...

St.I St.2 St,3 St.4 St.5 St.6 St.7 St.8 St.9 St.10

Temperature: 25*C

DO: 1 mg/1 in the initial

period at St. 1 and St. 10 and

5 mg/ at other stations *.

Interior test: Sealed airtight and left

(August 1981)

Figure 11. Release rate in Osaka Bay

Figure 12 demonstrates the release rates of phosphorus and nitrogen In

relation to the bottom sediment.

There is a definite relation between the content of T-N in the bottom

sediments and release rate for PO4 -P and between the conter., of T-N in the ".,'.

bottom sediment and the release rates for NH -N. It is also shown that under

circumstances where the contents of T-P and 4 -N are over 0.65 mg/g and 0.2

mg/g, respectively, there is a sharp increase of released P04-P and NH4-N.

Figure 12 plots the results of the released load test on the sediments with

the uppermost 50-cm layer removed. This figure reveals that removal of this ".

surface layer will lead to improved bottom sediment and a substantial termination of release. .-e

197

.d . .'- * * S °*-'*.* 
140 0

0 0 O120-0 y

"01- 0o (1)o ,; o0 o 50-80c.l.,,Ye"Z,

50 10 .. 0- :

0,, - ,0 0 0.2 0.4 0.6 0.8 1.0 l0 1.0 00 .0

lbottou sediment bottom sediment .

Figure 12. Relationship between release rates and bottom sediments ,.

0 0

"Relationship Between Pollution of Bottom r''-

Sediments and Benthos m

". ~The polluted bottom sediments and the deteriorated quality of the bottom "- .

-" ~layer of water are considered to have an adverse effect upon the benthic '

-i. biota. Figures 13 and 14 show the number of benthos species and diversity r :.

- l~ndexes, respectively. As the areas of the polluted bottom sediment spread, -. hthe seawater areas of poor biota where only limited ecospecies can survive ?

~~~expand in the offshore bay area. It should be noted hat there are areas ;.,.

.'. where the inhabitants' size is not more than 20/0.1 m (Figure 15). '-'-

Figure 16 shows the relationship between the surface sediments and the,....

"; diversity index of the benthos. This figure shows a decreased diversity index '

Uin the areas with increased COD, IL, and sulfide contents in the bottom

sediments. The grain size of the bottom sediments, the quality of seawater,

01~~ zw. .o-0;

? factors ~and seawater of the movement ecological are generally distribution considered to be the major controlling -. _ of the benthos. Accordingly,

"{ discussion of this problem solely from the viewpoint of the pollution levels .

of ' the surface sediments will not be sufficient. Nonetheless, the pollution

level in the surface sediments seems to be an important factor to control the

environment for the benthos.

Mechanism of Pollution 1 w n os'-i

In view of the results of our investigation, the pollution of Osaka Bayead,

e nseems to be caused by the mechnIsm as shown in Figure 17.

,_.-. - .

wher the inaitns siz is no"oeta 001 l(iue1)

F 1 sl h w...ss

d r i fgr s a d e d sy index

in. tcan

"%°%°°"." edimen.ts°% "... Th grai size of the .• boto ° . seiens ,•. th qult of sewaer %L 
,6 67 -7

NN

Kobeyam City

~~100-20

Aw:j 203

.. ~~ .. ....

199siad Ct
-F-Y-. Xp-j T3 -. 107 - 1V3mra 75M.-IM V. ST -- -'J

N

WAtAVAaa

.. .. .. .

Diversity index

Hi(s): Diversity index

Ni Population of the first species

NTotal population of individual

species

Figure 14. Distribution of diversity indexes of benthos

200
P.* %*

'iKoben City i.

cr- &0

Y~~ "to *s

Akashi ity201
-. ~~~~~~~- ~ . .. r e. I.....r 

6 . .

0 Ac0

0 0 1 ~ 04 0 .0

0.I *

0 CC*).

- .0 00* . r * 

0j " 0. - 4)

04K 4)

44

04

>W u

04 

0.

0 0

0 4J4r

0.0

0~0

0-

/00 . '.

202 . .
•..-..,

(Sun light)

Inflow loading from the

Dissolution of oxygen hinterland

Production of Phosphorus

(red tide) Nitrogen . .pla

t (Organic substances)

(Dissolved oxygen) "-.

Settling Settling

(Phosphorus, Nitrogen)

Constmption

of oxygen

Reduction of Release of Sedimentation of

o.-gen c nreut nutrient salts orgavic substance3

Approximately ___ 3C-50cm . organic Deco.--position materials by of bacteria ISediment Sedme.'mumud ":"'"

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

Figure 17. Mechanism of pollution in Osaka Bay

a. Organic materials in the sludge deposited on the sea bottom are

decomposed by bacteria.

b. During decomposition, the dissolved oxygen in the bottom water layer

is consumed to reduce the oxygen content of the bottom layer of

water.

c. As the reduction of oxygen content in the bottom water layer proceeds, the layer is reduced to an anaerobic condition.

d. Under anaerobic circumstances, nutrients (N and P) are released from

the bottom sediments.

e. Increased nutrient salts in the seawater caused an increase in the

productivity of plankton. Abnormal increase in the productivity may

promote occurrences of red tide. .. .

f. The debris of the dead plankton deposit to form organic sediments. """

203
-7-1 '-- L

r-~ C6

U A 0 UI

* .

0 0

to o .

Kz

VA40 c- OO 4.4

m d

-4 - 4 \

,4 1 -1

14 Aj

u %

CIO~

0204
This mechanism was simulated using mathematical models. Figure 18 shows

the balance of each material calculated using coefficients for summer conditions. The ratio of inflowing load from the coastal area to the released load

from the bottom sediment in terms of phosphoric acid phosphorus is 25.5 tons/

day against 13.7 tons/day; i.e., it was in the ratio of approximately 2:1.

This provides evidence that the released load from the bottom sediments

comprises the major factor of water pollution.

BOTTOM SEDIMENT CLARIFICATION PLAN

Removal of Bottom Sediment

The following effects are expected from removing the highly polluted

bottom sediment and the resultant improvement of the bottom environment. ...

a. Removal of the bottom sediments rich in organic matter will reduce

the sediment oxygen demand and thereby prevent the appearance of

anaerobic water masses in summer.

b. Removal of the bottom sediment high in organic and nutrient concentration, along with the resultant reduction of dissolved oxygen

consumption, will lead to decreased nutrient release, which is a

factor for eutrophication as seen in the frequent occurrences of red

tides.

c. By improving the quality of the bottom sediment and seawater, the

present benthos and other species whose variety is decreasing may be *..

improved.

Bottom Sediment Clarification '

It is necessary to provide standards for bottom sediment clarification on J.

the basis of the investigation results mentioned earlier, to the effect that

efficient improvement of the bay environment may be attained.

The following are example standards for setting up areas to be clarified

using the pollution indexes of the bottom sediment.

a. Standard by the organic pollution indexes:

rfT,,. = --7

COD > 30 mg/g (a)

Ignition Loss > 10% (b)

Sulfide > 0.6 mg/g (c)

b. Standard by nutrient release:

T-P > 0.65 mg/g (d)

T-N > 2.0 mg/g (e)

Figure 19 shows the area where two out of three conditions from (a) to (c) and

both conditions of (d) and (e) are satisfied. .

205
N

t Ko e C it

l ,-

Osaka Amashi~~~t.C+ I .kty, 

'16

I-,.•

Ct ~

Kishiwada City

Sennan City

" Wakayam,a 0 5 10km

c~1 ' City

Figure 19. Areas where the bottom sediment is seriously polluted

Methods of Bottom Sediment Clarification

Choice of Clarification Methods

The bottom sediment clarification methods are classified into two

groups: (1) the dredging method to remove sediments from the present site,

and (2) the field (on-the-spot) treatment method by confining the contaminants

at the present site (Figure 20).

The dredging method has a number of successful records in the port pollution prevention works in the past. Furthermore, in such a highly utilized bay

as Osaka Baky, this method, when combined with reclamation and beach nourishment, presented in the port development and utilization plan, will make it

possible to plan efficient and effective sea clarification works.

206

.. ."

• . . .
-- S. -o- . • . --. a -. -C" - -- - ..

.JDispos al by

I reclamatio

and disposal methods| r~ ed(nteso) at

- *4 .

treatment woo en

Figure 20. Choice of treatment and disposal methods

. There are three ways for disposing sediment dredged by this method:

. (1) disposal by reclamation, (2) disposal by dumping in the ocean, and

(3) disposal into beach nourishment sites (this method is similar to (1)). In

the case of reclamation, the reclamation work must be carried out according to

" the current social demand for land and only when the utilization plan of the

reclaimed land is definite.

In the case of dumping in the ocean, although the cost is low, no land

can be produced.

In the case of dumping into beach nourishment sites, dredged sediment is

utilized as material for forming a beach. This method can meet the social

demand for waterside areas.

For the field (on-the-spot) treatment method, earth covering is the primary way to dispose of the sediment. In this method, sand is overlaid on the

bottom sediment in the target areas to confine the sediments at the present

site within the layers of the bottom.

When considering both the degenerating capacity of nature's self- " % 

purification system due to the reduced natural beach areas and tide lands and

the shortage of recreation sites for people, it can be concluded that the

beach nourishment method meets the social demand.

Figure 21 is a diagram of dredging-beach nourishing work. Boats used

exclusively for sediment dredging that generate little turbidity were employed

for dredging organic sediments approximately 50 cm thick. The dredged sediment is carried to a disposal site by the boats for transportation and dis- "

charge. After the desired volume of sediment is dumped and adequately con- solidated, sand is overlaid on the disposed sediment to nourish the beach.

Technological Problems in the Bottom

Sediment Clarification Works .'

The bottom sediment clarification works (by dredging and dumping the

dredged sediment into beach nourishment sites) is classified into steps:

dredging work, disposing of the dredged sediment, and nourishing the beach.

-7p

207
Dredging Loading Transportation Unloading Dumping

Sludge dredger Barge loader Pusher barge Barge unloader Sludge disposal site

., 1:11

Suction head A work system in which sediment is dredged, loaded on a boat for

sediment transportation, and transported to a dumping site

(nourished beach)

Figure 21. Imaged diagram of work system

Figure 22 is the flowchart summarizing the technological problems drawn

by examining the requisites for these works based on the premises of the 5

work.

Dredging. Under the premise that the sediment to be dredged is thinly

deposited over a wide area, the technological problem is to establish a technique of dredging the thinly deposited sediment. By this technique, the

volume of sediment dumped into disposal sites will be reduced, and the reduction of the size of the disposal sites will have a considerable economic

influence. Accordingly, upon the recognition that the problem of developing

the thin layer dredging technique is an independent technological theme, we

are going to solve this problem by examining the past records concerning this

technique and by conducting necessary investigations and experimental work.

Disposal. The next premise is disposal of massive volumes of dredged

sediment. The requisites for this premise are (1) stabilization of embank- -

ments, (2) efficient disposal, and (3) stabilization of disposed sediment at

the disposal site in an early period.

The problem with designing a stabilized embankment (No. I above) is how

to estimate the pressure of earth and water upon the embankment. Since the

sediment to be disposed is super soft with a high water content, it is necessary to devise an efficient disposal technique for this type of sediment

(No. 2 above). Requisite No. 3 arises from the necessity to accelerate the

dehydration and consolidation of disposed sediment after its disposal for

prompt and smooth beach nourishment. Out of requisites 2 and 3, the following

five technological problems were extracted: high concentration dredging, separation of solid and fluid phases, high concentration discharge, understanding

the characteristics of volume change of disposed sediment with time, and ac- 9""

celeration nf consolidation.

Nourishment. The requisites for beach nourishment include: (1) feasibility of earth covering work where the overlaid sand is stabilized, (2) consideration for scouring and sand drift phenomena after beach nourishment is

complete (3) methods to prevent immersion of the contaminants from the

sediments under the overlaying sand (a requirement especially needed after the

completion of beach nourishment), (4) exchange of seawater, and (5) water

208 "

e . ... * . . * *
%A" - T~r-r-kW - W - -

14 (C

r.'

0I .0 -4 c -4Cu -4 

:L D~ ~ EnI~ 

ws

I1 -4 CU

0 a1 N 0 4 -4 a)

W 4 14G - to '.4 n wc 

WC- W-4 0 tI. G ZC 

'.4 a) -Z ;'

E( -U c4 4D 4-

-4 0 -4o

E v

C GO 

*20
tightness of the embankment. Out of these five requisites pertaining to beach

nourishment work, the following six items are drawn to be technologically

solved: (1) securing the surface-bearing capacity of dumped sediment,

(2) choice of surface treatment method, (3) earth covering technique,

(4) earth covering thickness, (5) measures against drift sand and scoring, and

(6) structure of embankments.

Upon examining the methods mentioned above, 13 technological problems

were extracted to be solved. Researchers at the 3rd District Port Construction Bureau are seeking the solution of these 13 technological problems by

conducting necessary experiments and investigations.

CONCLUSIONS

This paper reports on the study of the bottom sediment clarification

conducted by the 3rd District Port Construction Bureau to improve the marine

environment in Osaka Bay with the primary focus set upon the influence of the

accumulating sediments on the marine environment.

The followings are the main conclusions: .

a. Pollution of the bottom sediment in Osaka Bay is serious in the

offshore bay area.

b. There is a positive relationship between the areas of polluted

bottom sediment and the areas of degenerated quality of the '

bottom water layer. * .

c. Nutrient release is prominent in the offshore bay area.

d. Contaminant release occurs in the uppermost 50-cm layer of the

bottom sediment. Consequently, removal of this layer will

eliminate the release phenomenon.

e. The clarification method of the bottom sediment in Osaka Bay

that can meet the social demand is the dredging-beach nourishment method.

The authors are committed to finding the solution to the technological .'-

problems involved in this work.

r.

210 *4%° A
• . -

RESULTS OF SEDIMENTATION AND ELUTRIATE TESTS FROM OSAKA BAY SEDIMENT

H. Kosasa, K. Nikaido, and M. Natori

Japan Sediments Management Association

ABSTRACT

A study on sediment removal as it affects seawater pollution in Osaka Bay was performed by the

Japanese government. In relation to this, it has

become necessary to characterize dredged material

regarding sedimentation and elutriates. Consequently, sedimentation and elutriate tests were conducted in

1983. This paper reports the test results. e

SEDIMENT PROPERTIES

The sediment samples were taken from the area indicated in Figure 1.

Sediment quantities of 150 X were sampled from four points. The grain-size

distribution was obtained by three methods: conventional soil mechanics

methods, physical photo-extinction, and coulter counter (Table 1). The chemical and characteristics of the sediment in Osaka Bay are shown in Table 2. -._'.

SEDIMENTATION TESTS 1.-

The sedimentation tests were carried out principally to learn the effects

of coagulants on sedimentation. The results are shown in Figures 2 and 3. *

From these curves it is readily apparent that the settling velocities decrease .

with increasing sediment concentration. Therefore, dredging with higher sediment concentration is not always advantageous from the point of view of sedimentation. Figure 4 is a comparison of sediment curves with and without

coagulants for the same sediment content.

From the sedimentation curves the void ratio of the settled material at

each point can be determined. The initial void ratio of the sediment as it

lies on the sea bottom is 6.43 (w - 240%, Ys - 2.76). The volumes of the ..

solid particles, expressed as percentages of the total volume, were 3.51%,

7.79%, and 13.6%, respectively, for the three sediment concentrations of 10%,

25%, and 40%.

Since the initial concentrations of the dredged material are known, the

heights of solid to be settled (Figure 5) corresponding to the initial

211 ....

- .' . .%*
Kob

i Osaka

Sampling

A rea

Osaka Bay

Figure 1. Sampling area

fl TABLE 1. GRAIN SIZE DATA FOR SEDIMENT SAMPLES

-Size Soil Mechanics Test Photo-Extinction Coulter Counter

*Sand 0 0 0

Silt 82.5% 46.0% 55.7%

*Clay 17.5% 54.0% 39.5%

D % 7 rni 55 uim 110 Jim

*D Z 25.5 urn 25 ium 33 I=m

30

D % 10.7 urn 11.5 lm 10 Uim

212
O.. 94-

TABLE 2. CHEMICAL AND PHYSICAL PROPERTIES OF SEDIMENT SAMPLES

Silty and

Appearance clayish Ignition loss 11.0%

Odor H 2S COD 39.0 mg/g

pH 8.4 TOC 3.31%

Wet weight 1.206 T-N 2,900 mg/kg

Dry weight 2.761 NH4 -N 95 mg/kg

Water content 240.0% T-P 830 mg/kg

Liquid limit 135.3% PO04 -P 230 mg/kg

Plastic limit 33.8% ORP -75 mV

cm Cm

80 0

-c 7G a 400Sededmeet

25cU 3 0 Wt ontent 

250/CoCoutent

40 10%

3Mihotc nte 30 nutes

Figur 2. Seietto uvsF gue3 Sdmntto cre

withoua t coaguanta t h ogln

- -' -. - - . .. -L I. -J 1 0
cm ..

1" -

Sediment Content 10%

~60 %'* ~q) .

Q L Without Coagulant I.- 40 -...-

20-

With Coagulant

0:.100 , inutes t Time

Figure 4. Sedimentation curves with and without coagulant

~J

Clarified

100cm Liquid

Pore Water Settled ;" Matter

Solids to b]q settled --- 4at'--

p corresponding to the

initial concentration.

Figure 5. Settled matter in column

214
concentration are obtained as shown in the tabulation below. However, the

actual height of the settled material is much larger because it contains,.e

water. The void ratios are calculated as shown in Equation 1. (The concentrations of solids in the clarified liquid were considered negligible.)

Volume of voids b - a (1) e Volume of solids a

where a and b are as tabulated below. *

a b

Sediment Content Solids to be Settled Settled Matter Void Ratio

(t 480 minutes)

10% 1.27 cm 31.3 cm 23.61

25% 2.82 cm 55.7 cm 18.73

40% 4.93 cm 98.2 cm 18.73

The ratio of volume occupied in the pond to volume occupied in the channel E

is an important factor for determining the receiving capacity of a pond. The

variable E is defined as:

e + 1 (2)

e +1 0

where

e f void ratio in the pond

e = void ratio in the channel

If E is larger than one, it is the swelling ratio of dredged material, But

the value of this ratio varies against time. Figure 6 shows the relationship

of E versus time. The value of E lies in a swelling zone for a settling

time of over 1440 min.

215

... -
0 200 4.0 600 g0oo i200 4 1600

Figure 6. Variation of void ratios for 10% sediment content

without coagulant

'1 .7- ..

-S- . P, " %

E

3

Figure 7. Variation of void ratios for 10% sediment content

with coagulant' -" '}

2.6

NE

• . -

0 0 o 2 ac co 1"- " '-400 

A -. * - . _ , - ,
ELUTRIATE TESTS

Elutriate tests are not standardized in Japan as in the United States.

Therefore, the tests were performed in the manner most usually adopted in

Japan. Their purpose is to learn the effects of sediment content on elutriates. The tests were conducted under the following conditions:

a. Flusco vessel volume: 3 X

b. Sediment content: 10, 25, 40%

c. Agitation time: 60 min

The test procedure is shown in Figure 8.

1000 RPM

~~~~amples,.'..'- Sediment

Vacuum Pump

trate > Analysis

Figure 8. Test procedure

Although the volumetric ratio of sediment to water is 25% in the guideline of elutriate tests in the United States, our tests are conducted with

three sediment contents as above.

*, , t • •**; . °. . r .- *. -

If we represent the initial concentration of a particular chemical parameter

in the sample as C and the corresponding concentration of elutriates as

AC ,we obtain 0

217

r,... . . . .-.
0.115

0 SAC/C -- 70 x 100 31%

9.

0.79

T-N AC/C 0 - 9 x 100 - 22.8%

NH-N AC/C 0.67 100 - 21.2% I

(COD) (AC/Co) 1.2 x 100 - 28.6%

- These results for elutriates are plotted for the three sediment contents as

shown in Figure 9.

40,

00 0 O

50 o T-N

... A NH4-N

A% X COD co 20

10

Rto-Cnetainat another sd. cont.9.

Concentration at 10% sed. cont.

Figure 9. Behavior of AC/C0

Figure 9 indicates that elutriate concentrations decrease according to

the increase in SS concentrations in the samples. It is presumed that the

disturbance torque does not prevade thoroughly to each individual particle.

The elutriate behavior of phosphorus is different from other materials.

As Figure 10 shows, the phosphorus concentration of elutriates reaches a maxi-

, mum after 1 min and then rapidly decreases. This is caused by the generation

of iron phosphate from to oxidation during agitation, which is then precipitated. The mechanism of iron phosphate generation is well known from many

studies on phosphorus release behavior.

218-

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

11 ... .. .. . . . . . . . . . . . . . . . . . . . . . . . .
-,d

45 Q3 Elutriate

"U Elutr-ate Oxidation

4)

0.1 Sediment Content 10%

E-4

0 10 is 5 60

minutes

Figure 10. Behavior of phosphorus

Figure 11 shows the mobilization of dissolved orthophosphate (ORP) from

the bottom sediment of standing water as a result of oxygen depletion and formation of H2 S at the sediment-water interface. The 'barrier layer' consisting

of iron (III) phosphate and iron (III) hydroxide serves as a sink for

phosphorus and is destroyed by the reduction process. .,

02 present NO00 2 _

NO H2S_____ -2 present

Watere; tion N ~ ', , ;:p0 ~ ~ :~ ~ .... edc lnI e ~n

teeoS ionl S e d itp ebi R educ- " .' :I "ea en-. v.'

Figure II. Mobilization of orthophosphate for sediment

CLARIFIED WATER

In order to accelerate the sedimentation of suspended solids, several

chemicals such as alum and polymers are used. The effects of these on

coagulation are shown in Table 3.

The table clearly shows that the combined addition of alum and polymer

- produces a much better result than the addition of only a polymer. But the

advantage of the combined use diminishes with the higher sediment contents as '.

shown in Figure 12.

2 1

21z9ii-.:,.

_____ _____ _____ _____ _____ ___ -
-~~~ -F01 -. -- --.... "'-. rTABLE 3. CLARIFIED WATER BY VARIOUS COAGULANT ADDITIONS 4

Clarified

Coagulant, m/I Water Combined

Sediment Content Alum Polymer Mg/t Only

10% -- 5.0 58.0 1.0

(SS 3.05%) 200 5.0 12.4 0.214

25% -- 25.0 292 1.0

(SS 7.98%) 500 25.0 212 0.726

40% -- 110 142 1.0

(SS 13.0%) 750 110 104 0.732

... ~i

1.0

,0.6

.

'0.4

8 0.2

0

10 20 30 40 "".

Sed. Content

Figure 12. Advantage of combined addition

The ratio of the concentrations at the combined addition to the ones that

use only a polymer is very small in the lower sediment content range.

Figure 13 shows the relationship between added quantities of alum and

turbidities of clarified water. From the figure it can be seen that the addition of only an inorganic coagulant, alum, has no effect on water clarification for the higher sediment contents. It is readily apparent that dredging

with higher sediment content is not advantageous from the viewpoint of

sedimentation. *'---

220 " "

.0

* -7
200

* 100

>-, 80 Sediment Content

4 u -40% ca 60-

-4 '-.

,.. 0-0 40 25 %0.-.'0''

= 20

100/.

10' a ., '.

200 400 600 800 1000 mg/ 1i

Alum ,.

Figure 13. Effects of alum on turbidity

CONCLUSIONS

From the preceding tests it was found that the sediment in Osaka Bay has

the unusual characteristic of sedimentation. -.5"

From the elutriate tests we have learned that the nutrient concentrations

in dredged material elutriate samples are not meager, but do not increase with

higher sediment contents.

The tests were conducted in accordance with the sediment removal project

promoted by the Ministry of Transport.

2.

221 -..R

,"-2. 4.'

p ..i,..
PARTIAL REVIEW OF DREDGED MATERIAL DISPOSAL TECHNIQUES

H. Koba

Nishiki Consultant Co., Ltd.

19, Kanda Nishikicho 3 - chome

Chiyoda - ku, Tokyo, Japan

M. Miyake

Toyo Construction Co., Ltd.

17 - 1, Naruohama 3 - chome

Nishinomiya, Hyogo, Japan

ABSTRACT M _,

Coastal disposal areas containing dredged sediments contaminated with hazardous material are not

easily reclaimed into stable land areas. The tech- .' 'a

niques for predicting the period required for disposed

material to become stable through sedimentation and

self-weight consolidation have progressed, but are not a.

yet satisfactory. This paper views the techniques for ' .

predicting sedimentation and self-weight consolidation

of disposed sediment in Japan.

INTRODUCTION -.

In recent years, dredging for industrial area reclamation and environmental improvement and maintenance dredging in waterways and anchorages have

been increasing in Japan. With the relatively small amount of available land '

in Japan, creation of additional areas of land by depositing dredged material

along the coast has been the popular method of disposing a large amount of

dredged material. The effective disposal of such a large amount of material

has become a large problem. Primary geotechnical considerations are the

amount of storage capacity that must be provided for a given dredging rate,

the amount of subsequent subsidence, and the future land-use capability of the

dredged material.

This report reviews the following techniques relating to disposal of

dredged material: (a) prediction of surface settlement due to sedimentation

and self-weight consolidation, and (b) consolidation tests to obtain the input

data for the numerical consolidation analysis. A site application example is

also given.

SEDIMENTATION AND SELF-WEIGHT CONSOLIDATION

The first quantitative analysis method in Japan on consolidation in which

the self-weight of the fine-grained dredged material was taken into account

222

-'a.- -.- ... . . .. ° . . . . . A.. ' -
was the one-dimensional consolidation equation developed by Mikasa (4) in 1963

in analyzing the ground improvement test for lowering the water level after

reclamation in the Port Osaka South reclamation work.

The analogous alluvial clay consolidation process provides the relationship that the consolidation time is proportional to the square of the layer

thickness. Upon consolidation of the highly hydrated clay such as the dredged

material, however, the coefficient of permeability (k) and the volume compressibility (mv ) are greatly reduced. The variation of the coefficient of consolidation (cv = k/mv r w) may not be ignored due to the dependence on the- rvariation of k and m . When consolidation is highly affected by the self- ,

weight and the variation of the layer thickness is great, the square rule %*.

stated above is not applicable. Therefore, the following equations are

developed.

(1) Correlation between stress and strain stated above . . . *..

Non-linear ideal elasticity

m = de/dp : Volume compressibility (1)

(2) Equilibrium equation

3p'az j J + r' (2)

where

j - (seepage pressure) i *

i - (hydraulic gradient)

r unit weight of water

r' - bouyant weight of soil particles

(3) Equation of motion . . . Darcy's law assumed

v(flow velocity) - k • i (3)

(4) Stress components of the soil matrix and pore water (soil

particle and pore water are incompressible)

P (total stress) -p + u (4) a

where

p - effective stress

u excess pore water pressure

(5) Equation of continuity (transient)

-e3 3v/3z(5

223..-.
When Equations I and 2 are substituted into Equation 3, the following equation

is obtained:

v - c v (ae/az - m v - r') (6)

When Equation 6 is substituted into Equation 5 and if c ±. the function of

strain e , the following equation is obtained: v

a; C Cv 

2 Cv2) (L (Cv my r') 21(7)

1 0 d z Ca Jz2 

where

(consolidation ratio) - fo/f

f - volume ratio*

f - initial volume ratio 0

z° - original coordinate

OW( -cv c/vo

Upon applying Equation 7 to the site test stated above, the linearity,

f - log p , is assumed for Equation I and a finite difference method is

applied. This theory suggests that the clay settles in water initially at a

constant velocity of v = k * ro'/r w ; therefore, this velocity is determined

by k and r' , but is independent of the clay layer thickness.

Mikasa and Takada (7) studied the self-weight consolidation of a very ,' soft clay with a uniform water content (single layer filling) using a

centrifuge. Briefly, the stress condition of the clay sample with a layer

thickness H subjected to the n * g (g gravitational acceleration)

centrifugal acceleration field developed by using the device and container

" shown in Figure 1 has the same effect as a sample with n times the unit

volume weight and is similar to the clay layer with a layer thickness, nH in

a 1-g environment.

Using the relationship between the prototype (p) and model (m) with the

following expression:

settlement S p - n * Smm (8)

2 consolidation time t n . t

the water content was changed to the 10-cm-layer thickness in the 100-g

centrifugal acceleration field, which is shown in Figure 2.

.--.. '.

, Editor's note: Japanese researchers utilize the parameter volume ratio,

f , f = V/V where V is the total volume of a soil mass, and V is the

Ss

volume of soil solids. f equals (I + void ratio).

.' 224

". -

* . . . . . - - . - -. . . . . - . . . . . . . . . . . . . . - . . - .: _- - 4- : . -. .- . .... <-, ' -. - '* . -, - - " ' -""' d - --- " - .'
% %.

nir-sh saet- cve

container bucke t c

Figure I. Centrifuge facility

t (min

0.

-1 % L ' 30'*\ *

U 8.0

500

0 to too 000 5

Elapsed time (as

2250
Thereafter, Mikasa, Takada, and Li (8) in 1976 studied the influence of

the coefficient of permeability of clay on the sedimentation velocity during

self-weight consolidation. A major objective was to assess feasibility of the

projected capacity of the disposal site with the limited reclamation schedule

of the dredging and disposal plan for the surface layer of the seabed clay

contaminated with hazardous materials. In other words, when the clay in the

initial uniform condition is consolidated by its self-weight only, the strain ,

in the clay layer is transmitted from the top to the bottom, and, at the upper

portion of the clay layer where the strain in the initial stage of consolidation is not yet transmitted. The surface of the deposited material settles

initially at a constant velocity of v = kr'/r . Therefore, this velocity is

o w

determined by k and r' I but not by the clay layer thickness. 0

Figure 3 shows the sedimentation condition characteristics of the dredged

material, i.e. the variation of the coefficient of permeability and effective

stress obtained through the self-weight consolidation test in a 1-g environment and the centrifuge.

In 1978 Takada (10) applied the result of the test described above to a %

practical problem. As shown in Figure 4, adequacy of the capacity of the

dredging disposal pond was studied. In this study, the water content of

15 1 I I I I I I It1 0

PJ:51&0006 85cr)

P6 I -4I

S00

0 CO

100

Permeability (cm/sec)

(a) _-_"."__"

45-1_ _ __ _ _

p -~'44.0

."4 3.5 -

U~~ 30__ _ _

0 2.5 0 3.02

Effective stress (t/m

(b)

Figure 3. Relationships (a) f log k

and (b) f- log p

226

o•
2 IV V.

d0

0 too 100

jy&-- m

00 I * I . . . I "". "'

Elapsed time (days) WK

Figure 4. Example of planning dredging and

reclamation activities

material hydraulically dredged was estimate,! to be 450X, and the bulking

factor was assumed to be 2.21. The layer thickness of the filling soil was

estimated to be 1.8 m, and the overexcavation to be 17.25 m at 25%. Under

-4

these conditions, v - 2.1 cm/day was obtained, where k - 1.9 x 10 cm/sec,

r' - 0.126 t/m , and f - 12.97. The maximum usable ground height of the

0 r

containment area was determined to be 12.5 m. Since a scheduled material

thickness of 13.8 m was planned to be filled in 100 days because of the pumping capacity, a 1.8-cm/day rise in the ground surface was assumed. In addition, a 2.1-cm/day sedimentation rate was estimated along with a 13.8-cm/day ..-.

rate of filling; therefore, eventually, the rise in the surface level within

the containment area was 11.7 cm/day.

If the scheduled thickness of 13.8 m is continuously applied, the ground

height becomes 11.7 m, which has an 80-cm allowance with respect to the 12.5-m

disposal field capacity. When the 25% overexcavation is filled, the height

reaches 12.5 m in 107 days. As shown in the figure, if an interval of 50 days

is provided, a 105-cm settlement is generated.

Therefore, filling was conducted for 9 days at a velocity of 1.8 cm/day;

then after sedimentation, filling was continued.

Imai (2) performed many sedimentation and self-weight consolidation tests

for the dredged clay. He divided the sedimentation process into interface

sedimentation and consolidation sedimentation as shown in Figure 5. The

effects of the soil particle weight, salt concentration, and initial water 10

content to the water content of this interface are summarized in Figure 6.

Yano and Tsuruya (17) implemented single-layer and multi-layer filling

sedimentation tests to determine the sedimentation and accumulation characteristics of slurried fine-grained dredged material. In doing so, the area ,.

and capacity of the reclaimed land necessary for the work plan could be determined and the scale of the sedimentation basin (to prevent outflow from the

227

I.
:: , ...-. I M ~ U. w %

Elapsed time Clog (mai)) Elapsed time (log (mai))-,L... i2 i

• %

Figure 5. Process of sedimentation t and S- self-weight consolidation ,l "-

pond)cntnt %)Water content ()=

.', Figure 6 Effect of water content and soil particle weight"--

could be studied. From the single-layer filling sedimentation test

result, the correlation between reclamation layer thickness and soil particle ,-,

height (H_) is shown in Figure 7, where the self-weight consolidation starting n i

*point is 5 to and the self-weight consolidation ending point is tl0 ii !

00

In the multilayer sedimentation test, the correlation between filling"-'.i-"

Jo~- ,1 -, .. /00

velocity and accumulation velocity is summarized in Figure 8. From this correlation, it was reported that the accumulation velocity would be constant if

the filling velocity was constant.

Yamanouchi et al. (16) found that the correlation between the practical . ~ *soil height (Hs ) and the accumulated sample height (H), obtained from the con-.,.'.

tamned soil particle amount, becomes a straight line on a log-log graph if the self-weight consolidation degrees are the same. They reported that the practical soil particle height and the accumulated soil layer height in the '""'

reclaimed ground could be obtained from this linear relationship. .'''

In a maintenance dredging project (3), a method was shown which demon-,'".'"' -

strates the correlation between the capacity of the disposal pond and the dis- -

posal amount from the sedimentation test result. In other words, using the

WSr

. .0. o

,d-.- 'J" .' .' -" .'-' '_. ' _ J ' .. ' ' '_ '_ " ,." " ,J '. °, " ". , ", " " " " " ... " '.-.".
• .. .. .

I

Soil particle so

height (cm)

4 -

20- -

2 3 4

0 I I I IElapsed time (min x 104) "

Figure 7. Relationship between Figure 8. Multi-layer sedimentation curve

reclaimed height and

soil particle

results obtained from the single-layer and multi-layer sedimentation tests,

the correlations among H10 0 (the layer thickness at the end of self-weight

consolidation:cm) H (practical soil particle height:cm), filling velocity s (cm/day), accumulation velocity (cm/day), elapsed time (days), and accumulated layer thickness (m) were obtained on log-log scales as shown in Figures 9-11.

I I I

U

0 -. " - °°

( -3

1-

Soil particle height (cm)

Figure 9. Soil particle height vs. final height

Predicting the ground height using Figure 11 is explained as follows. "',"-.-

During the filling phase, the dredged material surface rises at a rate of

v 1.97 cm/day and reaches point B after continuous filling for 200 days.

229

* . . . . •. - .
U Figure 10. Filling velocity vs. ascent

- velocity

>

U

Filling velocity (cm/day)

fi Hing Period

- 200 days

S.

D

B'c

. ., 0 0 '.-

0

0 IL-0DOP

0 M7. 0 7

/0 s0 1i Soo 000

Elapsed time (days)

Figure 11. Elapsed time vs. height

The practical soil particle filled during this period is 0.35 m 3/m2 . From

Figure 9, it is found that the accumulated layer thickness at the end of

self-weight consolidation, H10 0 , is 2.25 m. Accordingly, the dredged

material surface that reached to point B in Figure 11 settles to point A.

Points D and C are obtained in the same method.

On the other hand, Takada (11-13) presented a numerical calculation

example of Equation 7 according to Mikasa's theory in different boundary

conditions and supplemented the calculation example in Mikasa's thesis of

1963. Among them, the paper in 1980 (2) dealt with the self-weight

230. .

230. -, '.,..

*-%". -
consolidation of the soft clay layer whose layer thickness gradually in- creases. The clay whose void ratio is relatively small (e° 3.2) as dredged "

soil is reclaimed on the permeability layer in sea. The similarity accuracy

was changed to eight steps in case the layer thickness was in proportion to

time and the gradual increase of the layer thickness was similarized with the

step-by-step increase under the condition that c is constant during consolidation, and the time until the final layer thYckness was changed to the

time factor Tf = 0.025 to 0.2.

In the same project previously introduced (3), Miyake and Akamoto (6)

performed numerical calculations for some examples by preparing a program to

account for the lowering of the water level and negative pressure effects

*" after filling, covering soil.

CONSOLIDATION CHARACTERISTICS OF DREDGED SOIL -'

The methods for determining consolidation and sedimentation characteristics and elapsed time for consolidation were previously discussed. The following paragraphs introduce the consolidation constants required in the method

(i.e. the correlation f - log p or m for the former, or k and m or

cv (=k/mv r ) for the latter. v

Mikasa (4) implemented a conventional consolidation laboratory test to

determine the influence of consolidation characteristics of the very soft clay

on the settlement of the reclaimed land at the Osaka South Port. He used an

improved apparatus to avoid problems with the fine-grained material seeping

through the consolidation ring. W .

Thereafter, Mikasa, Takada and Lee (8) obtained the f - log k relationship for Tokuyama clay as stated before and the f - log k relationship for

Osaka South Port clay using results from the self-weight consolidation test,

the conventional consolidation test, and the consolidation test using

centrifuge.

Imai (2) thought that consolidation constants in the low-stress range

would be necessary for calculation of the self-weight consolidation and .% '.

therefore obtained the f - log p relationship from the sample soil following ..

*- the soil sedimentation test. In other words, the vertical profile relation-

- ship between f (calculated from the water content after the self-weight

consolidation) and the effective stress p at each discrete depth was

obtained from the following equation

fi I + Gs • w

r- (Gs - Gw)rw/fi (9)

P WrlAz , ~ + rjAzi/ 2

where Azi - the representative change in depth for slice i.

-S".. . "

231

pIr
The stress range was quite small in the above method, so Imai (1) proposed a consolidation test method using seepage force. The material slurry is

put into the transparent container as shown in Figure 12, and the clay is

V7 h

Z Figure 12. Fundamental ideas i v ]of hydraulic

~Iz

,11 Pj_ consolidation ,

hrw

(II (2)

consolidated by the combined effects of a seepage flow as well as its selfweight. After completion of consolidation, a thin pipe is inserted into the

bottom of the clay layer step by step and the distribution of the pore water

pressure is obtained. Then, from the void ratio obtained by cutting the clay

to proper slices, f and r' are calculated using Equation 9. The

f - log p relationship is obtained from fi and the corresponding consolidation pressure pi " Pi is obtained by deducting the pore water pressure from

the total stress obtained by adding rt to the clay layer upper surface water

pressure as shown below. t

P, - (h r +Er 1 A + r z /1~i2) -u (10)

The coefficient of permeability is given by the following expression:

ki - ir (".- 0\(p/ w

Umehara and Zen (15) proposed a method using the constant rate of strain

consolidation test. In other words, in Equation 7 of Mikasa's theory, the

effect of the self-weight is ignored, under the condition that cv is

constant; the relationship is obtained from the equation shown below through -.

differentiation assuming that the displacement velocity is constant.

as C 2 2

S c 2 2 (12)

az0

2 3 2lit- Ao

232

• -... ........ .. °.•... ... •........................ ... " %
By applying the curve fitting method to Equation 12 and the test curve, c

was obtained. The f - log p relationship can be obtained from the actual

measurement of volume displaced and effective stress (total load minus pore

water pressure).

However, since the method described above is complicated, a method was

proposed for obtaining c by plotting test values on Figures 13-14 incorporating Equation 12 intov AH /H (average deformation), f t/f (upper end

surface consolidation ratio), fb/fo (lower end surface consolidation ratio),

and F (upper end surface to lower end surface strain ratio -

log og £.

AHo/Ho /Ho.- -.

0 01 02 030O405 06 07 0.1 02 03 0.4 0.5 0.6 0.7

&M 1.11.0 t 

2 1.2

*1.5 I .13

:A\ L4

20 .5.5

1 2 1.7 , Ho.mo hN 1.7

1.501.9

35 351! I i .. ,.-

.02 0.3 0.4 0-9 0.6 0.7 1 0 0.1 0.2 0.3 0.4 0.5 0.6 07

Figure 13. Variations of consolidation ratio at the top and bottom of the

specimen for average strain.'.*" .°'

&Ho/Ho

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 "*'

0 0

0.1 Minok.NOI 0.2 02 mol NCO. 13 0 .2..-.

0.3 0.3

0.4 0.4

0.5 0.5

0.6 0.6 A

0.90

1.01 1.0

0 0.1 0.2 0.3 0.4 0.5 06 0.7

Fig.2-9 F-aHo/Ho

Figure 14. Variations of the ratio of

bottom strain to top for

average strain

Takada (11-13) obtained the f - log p , f - log k , and f - log c

relationships of the Osaka South Port fine-grained material over a wideVrange

including the low-stress range obtained with the centrifuge.

233

S . 6°.

.°° ° ° -s
_2~~~~ ~ ~ ~ ;- ~ ., . , 7;V;W .. 

Toriyama (14) obtained the consolidation characteristics of the reclaimed *.

soil of the Hikono District Chukai reclamation through the tr-axial compression test. cv was obtained through the "t method." Also, he implemented

the self-weight consolidation test and obtained cv by curve fitting from the

relationship between the settlement and time. He reported that the ordinary

stress range result would be applicable to the low-stress range.

SITE APPLICATION

Applications of the previously described laboratory and analyses methods

(including the model test using the centrifuge facility) are described in

Mikasa and Takada (7, 8), Miyake and Akamoto (6), Umehara and Zen (15),

Takada (13), and Toriyama (2).

Mikasa's Osaka South Port reclamation settlement analysis (4) and

Tokuyama Port dredged material disposal land capacity feasibility study _--__

(8, 10) were used as the site application example.

In addition, Nakamura (9) studied the applicability of the model test

using Mikasa's theory and centrifuge facility for the preparation of a

reclamation plan standard for the Chukai reclamation Hikona District:

a. He implemented the centrifuge-based self-weight consolidation test

(acceleration = 33g, scale - 1/33, model layer thickness - 15 cm,

initial water content = 303%) in the centrifuge. The consolidation .-.

time was 25 hr (actual time = approximately 3 years), settlement was

5 cm (166 cm at site), and Cc was 1.4 to 1.8.

b. For the initial condition for numerical analysis through Mikasa's

theory the initial void ratio was unity near the surface layer after -"."

reclamation. After the calculation using w - 300%, Gs - 2.65,

f = 8.95, reclaimed layer thickness H 0 -5 m, single drainage, C c

1.4, p 0.00914 tf/m 2 , and cv 0.015 m2 cm2 /day , the final

settlement was 1.246 m.

From these results, he reported that the model test method using Mikasa's

theory and centrifuge facility would be effective in applications to the site.

Miyake (5) attempted the application of Mikasa's theory to determine

surface settlement times and ultimate ground height in Takuma Port Reclamation

Work. Two months after reclamation he sampled the soil using a soil sampler

that excluded mud and obtained the water content distribution in the layer

50 to 300 cm. Using Equation 9 from the conventional consolidation test and

self-weight consolidation test, he obtained relationships of f - log p and

f - log cv from the actual measured values and calculated value of the water

content, and, as a result, obtained the relationship between settlement and .-.

elapsed time.

He reported that these would be well explained by Mikasa's theory.

234

-.. . . . . . . - .. ,
•Z 0

CONCLUSIONS i

More effective methods for disposal of bottom sediment containing contaminated material are necessary in Japan. Accordingly, the major analytical

technique for this purpose, the consolidation settling equations, needs to be

made more accurate.

The author sincerely hopes that this paper will be of some help in

realizing these goals.

REFERENCES

1. Imai, G. 1979. "Development of a New Consolidation Test Procedure Using

Seepage Force," Soils & Foundations, Vol 19, No. 3. -"

2. Imai, G. 1981. "Experimental Studies on Sedimentation Mechanism and

Sediment Formation of Clay Materials, Soils & Foundations, Vol 21, No. 1. r

3. Japan Dredging and Reclamation Engineering Association. 1984 (Apr).

"Report of an Investigation About Techniques Cleaning Osaka Bay Bottom

Materials." 

'

4. Mikasa, M. 1963. "The Consolidation of Soft Clay - A New Consolidation _."

Theory and Its Application," Kajima Institution Publishing Co., Ltd.

5. Miyake, M. 1982 (Jul). "Numerical Consolidation Analysis with SelfWeight and Layer's Change on Very Soft Clay," Toyo Construction Technical

Research Institute, Vol 9.

6. Miyake, M., and Akamoto, H. 1984 (May). "Numerical Consolidation Analysis Considering Single- and Multi-Filling, Water Level Decreasing Under

Decreasing Applied Load and Self-Weight Consolidation," The Reports of

Toyo Construction Technical Research Institute.

7. Mikasa, M., and Takada, N. 1966. "Self-Weight Consolidation Test Using

Centrifugal Force Facility," Proc. 21th Annual Meeting of JSCE.

8. Mikasa, M., Takada, N., and Lee, K. 1976. "The Consolidation Characteristics of Very Soft Clay," Proc. 11th Annual Meeting of JSSMFE.

9. Nakamura, R. 1982. "The Study on Soil Engineering Characteristics of

Disturbed Clay (II) - Characteristics and Settlement Analysis of Reclaimed Soil," The Reports of Agriculture Civil Engineering Technical

Institute, No. 22.

10. Takada, N. 1978. "Engineering Problems of Waterfront Reclaimed Land,"

Chapter 2, Settlement of Waterfront Reclaimed Land, Lecture Textbook of

JSCE K Ansai Branch.

11. Takada, N. 1979. "Consolidation Process Associated With Variable Coefficients of Consolidation and Decreasing Thickness of Layers," Soil &

Foundation, Eng.

• 12. Takada, N. 1980. "Some Examples of Numerical Calculation of One Dimensional Consolidation," Soil & Foundation Eng.

13. Takada, N. 1983. "Numerical Analysis of Self-Weight Consolidation of

Very Soft Clay," Soil & Foundation Eng.

235 >:.•:
04

14. Toriyama, K. 1981. Consolidation Properties of Soft Reclaimed Clay and

Prediction of Consolidation Settlement by Dead Weight, Trans. JSIDRE.

15. Umehara, Y., and Zen, K. 1980. "Constant Rate of Strain Consolidation

for Very Soft Clayey Soils," Soils & Foundations, Vol 20, No. 2.

16. Yamanouchi, T., Uehama, T., Ishibashi, T., and Yano, K. 1983 (Jun).

"Characteristics of Pump Dredged Clayed Deposit in Hakata Bay," Soil & '.

Foundation Eng.

17. Yano, K., and Tsuruya, K. 1982. "Sedimentation and Soil Properties of

Fine- Grained Slurry Materials," Proc. 17th Annual Meeting of JSSMFE.

236 .

A-
LIME-CEMENT HARDENING OF VERY SOFT FRESHWATER CLAY

M. Kamon

Associate Professor

Department of Civil Engineering

Kyoto University

Yoshidahonmachi, Sakyo-ku

Kyoto, Japan, 606

*,. .. ...

ABSTRACT

Soil stabilization problems for a very soft

ground tormed during land reclamation by filling in a

lake were treated with a lime cement mixture treatment. The usefulness of the hardening treatment was

shown in the laboratory using several stabilizing

agents. It was clearly shown that fine particles

solidified by pozzolanic products were needed for good

hardening, although a great amount of fresh water was

fixed into the ettringite crystal and the handling

properties were improved.

INTRODUCTION

It takes a long time for very fine clay particles to settle in fresh

water because their interparticle repulsive forces make them suspend; therefore, after sedimentation a very soft surface with a high water content is

formed. Because of the high water content, soil improvement is very difficult. A pollution potential exists during reclamation work in lakes and

ponds, from these suspended fine clay particles because they can flow out to

open areas without sedimenting inside the reclamation pond.

To prevent this pollution a retaining basin is often built at the part of

spillway in a reclaimed area and water treatment is used to accumulate the

fine clay particles. A large retaining basin, however, is needed to obtain

good accumulation and the basin becomes an obstacle to effective land use because the basin is in a very soft condition at the end of the reclamation

work.

An artificial island, which is an example of this kind of reclamation

works, was constructed in 1980 south of Biwa Lake in Shiga Prefecture, Japan.

The retaining basin in this reclamation was 11 ha which is one seventh of the

total area of the reclamation project, 73 ha. It is still too soft for construction machinery. Therefore, soil improvement or hardening is now

required.

The purpose of this study was to investigate the possibility of using the

hardening treatment, which is introduced by lime and cement mixture, for very

soft freshwater clay in the laboratory. Special attention was paid to obtain

a suitable stabilization mixture. It was hoped to fix a great amount of fresh

237

-? . .. . . ... *. .. .. . . .. . . . .*...*:*'., . . . . . , . ....-.............,-. -,... ... ...
water into the crystal of ettringite and to obtain a stable ground cemented by

lime and cement stabilizer. I'-'-.

ENGINEERING PROPERTIES OF VERY SOFT CLAY

The reclaimed soil was dredged from the lake bottom with a soil profile .. consisting of sandy and gravelly soils, and transported to the reclamation

* area by a pump dredge. The coarse particles, such as sand and gravel, precipitated rapidly near the end of discharge pipe and thereby formed hard ground.

On the other hand, the fine particles, the silts and clays, were thrown out

far from the discharge pipe and accumulated around the wasteway of the reclamation pond. Since a retaining basin at the part of the wasteway had been

built in order to treat water and to prevent outflow to open waters, the accumulation of very fine clay particles accelerated especially. These particles are still in suspension several years after the end of the reclamation

work. The water content of these soils under the slurry condition is

150-200 percent.

The engineering properties of this soft clay soil are listed in Table 1.

This is a highly plastic soil. The particle-size distribution is colloid and

* clay particles as shown in Figure 1. An X-ray diffraction pattern of this

clay soil is illustrated in Figure 2. The dominant forming clay minerals are

- halloysite and kaolinite. Illite and montmorillonite minerals are contained

with fine primary minerals such as quartz and feldspar.

A sedimentation test was performed using arranged samples which were set

at 250, 500, 1,000, and 2,000 percent of the initial water content. Sedimentation properties were obtained as in Figure 3. The interference sedimentation is observed in 250 and 500 percent of the initial water content samples.

It clearly shows the high water content of the soft ground under the in situ

slurry state condition.

The bearing capacity of this clay soil in relation to the water contents

was examined by the vane shearing test shown in Figure 4. The dewatering of

the samples was forced by vacuum suction. The shearing strength at 150 to

200 percent of water content is 0.5 to 3 kPa, thus indicating quite soft

ground.

TABLE 1. TESTING CONDITIONS

Factor Condition

Initial water content (%) 150, 200

Mixture percent (%) 5, 10, 15, 20, 30, 40

Combination ratio (P:L) 9:1, 8:2, 7:3, 6:4

Specimen size (mm) 50 (h) -100 

Curing temperature (*C) 20 ± 2

Curing time (day) 7, 30, 60, 90, 360, 720

238 K .:... 4 KQ W 1 .-... . - : • .-?.< 
100 - Sand 0. 3

* so I Silt 24.0% - *.

i I I

* Colloid 49.1 106-

~' 20- 1 _ 1 1 1

0A o.002 0.01 0. 05 0. 10. 2 0. 5 1. 02. 0 5. 0

0.001 0.005 0.02

Effective particle diameter (mm)

Figure 1. Particle-size distribution

~~~~Halloysite alose

1Caoln t Quartz i Quartz FeldFldspr

Montmorillolite

20 40 104 200 -30

Figure 2. X-ray diffraction pattern (Cu-K)

239
-. - - - 61 

fl100 N

90

0 80".-

'' 70

0 60 - Initial slurry oono.

,. 5 (water oontent)d

0

> 40 - :.j t 0O 

30 -O9 II 

S20 N:~0

ci'2~~ _ S__ 0__0

1 10 100 1000 10000

Time (min.)

Figure 3. Sedimentation properties

0~

10~

040

0 00

54

0.01

100 120 140 160 180 200 220 240 260 IA

Water content, w ().-

Figure 4. Vane strength

240

0 ~ ~ ~ ~ ~~J ; 7; -'.... ..... '**-* -
STABILIZING AGENTS AND EXPERIMENTS PERFORMED .

Stabilizing agents used

In order to improve the engineering properties of this very soft clay

ground, the soil hardening technique with lime or cement addition was chosen.

Lime alone or cement alone did not cause any hardening in preliminary tests.

Hence, a special stabilizing agent which can reduce the free water by enclosing water into ettringite crystals was introduced. A lime-cement mixture with

a' minum sulfate [A1 2 (SO4 )6] was used with varying relative proportions of

their contents. The proportion of lime to cement was mixed in the wfight

ratio of 2 to 1. The combination ratio of lime and cement mixture to liquid

aluminum sulfate was varied in the weight ratio of 9 to 1, 8 to 2, 7 to 3, and

6 to 4. These stabilizing agents were added into the soil samples at 5, 10,

15, 20, 30, and 40 percent of the soil dry weight.

Experimental procedure

The varied water contents of the soil sample were 150 and 200 percent.

These correspond to the in situ water content. The effect of the hardening

treatment was examined by the unconfined compressive strength of the treated

samples. (The testing conditions were listed in Table 1.) P:L in the table

means the ratio of the powder mixture of lime and cement to liquid aluminum

sulfate. The soil samples were mixed with the stabilizing agent for 10 min.

After the samples were put into the cylindrical containers without entrapped

air, they were covered by a thin plastic film and then cured at constant

temperature.

In order to determine the reactive products of the added stabilizing

agents, X-ray diffraction analysis was applied for specimens which had been

used in the unconfined compression test. It is considered that X-ray intensity of the reactive products indicates their content; namely, I is the

X-ray intensity of ettringite crystal, 20 - 9.080 and ICSH is one of CSHseries products and tobermorite. These reactive products were also observed

by a scanning electron microscope.

HARDENING CHARACTERISTICS

The unconfined compressive strength of treated samples is shown in Figure 5. The results of the samples with an initial water content of 150 percent are shown in Figure 5a-d. Those with an initial water content of

200 percent are shown in Figure 5e-h. These figures show the curing effect in

relation to the added volume of stabilizing agents. The compressive strength

increased with the duration of curing, and a special increase in the strength

at 60 to 90 curing days was observed. The treated samples under 150 percent

of initial water content, 9:1 combination ratio, and more than 15 percent adding volume conditions have a great increase in their strength. This, however,

tends to decrease for the smaller combination ratio of the treated samples.

This means that the enclosed water into ettringite crystal may cause the

strength decreases to the treated samples.

241
40f4 W40

1.0 1±5I05N 1.0 P L 8 30 P: L=9: 1 30* 30 -W*I=.

4 

.

0.001 001 7

00

60 30 2 0

7 30 6 0 360 720 600 

Curing time, To (day Curing time, To (day

a. Initial water content (Wi) =b. Wi 150%, P:L =8:2

150%, P:L =9:1

((d)

1.0 F61i= 15 0*001. i101

c P: L=7 :3 ~ IP L=0±4 40

30 0 30%

0

0 0

'0

0 0. 00 -

7 3 ioq36 20 73 09 30 72

(day ) .rfStm o (day

c. Wi 150%, P:L 7:3 d. Wi =150%, P:L =6:4

Fiue5. qu curing time (Continued)

242
I T

040

20 03

0.1 0.1

15 V 0

0 0

0.1-,0. 0 00

0 010

_00

0. ooi 7 .1 0.0011 30 60090 360 720 7 30 6060o 360 720 5

Curing time, Tc (da0y )Curing time ,To (day

e. Wi =200%. P:L =9:1 f. Wi =200%, P:L -8:2

1.01 Wj

* 40

* 40,

0'0

.......... 5

* 0 1

0200

em

0 (.0

* 20

* 0

0 0 CC

00S

0.001 t- _ _ _ __-1- f 7 30 60 90 360 720 730 f, 00 1) -N

Curing time, To (ay) (-.ring tin. (SA 'La

g. Wi =200%, P:L - 7:3 h. Wi 200%, P:L -6:4

Figure 5. (Concluded)

243
The treated samples with 200 percent initial water content had less

strength than those with 150 percent initial water content as shown in Figure 5e-h. However, the initial strength (7-day strength) was almost the same

at both 150 and 200 percent initial water contents. Their unconfined compressive strengths did not differ at the different combination ratios. On the

other hand, the long-term strength (more than 90 days) was quite different

between samples. The increased strength at the 6:4 combination ratio was the

least of all treated samples.

It is generally said that the bearing capacity to obtain trafficability

on soft grounds is more than 30 to 50 kPa in q value. In order to obtain

this value, the required volume of added stabilizing agents is more than 30 to

40 percent in the 150 percent initial water content sample according to Figure 5. The most reasonable solution for the added volume is about 15 percent

at 60 to 90 days of curing periods because the treated samples by higher added

volumes (30-40 percent) show excess long-term strengths (700-1500 kPa). Ex-

*. cessively solidified ground which will become an obstacle to construction must

be avoided.

The unconfined compressive strength in relation to combination ratio and

added volume is shown in Figure 6. The increasing strength in samples of 9:1

and 8:2 combination ratios and at more than 15 percent added volume was

' clearly illustrated in the slope shape of the figures. Generally speaking,

- the bigger combination ratio samples (those which produce the pozzolanic reactive products), have the greater improved effect.

HARDENING MECHANISM

The hardening mechanism of the lime-cement mixture treatment was examined

with a scanning electron microscope and X-ray diffraction analysis.

A large number of needlelike crystals of ettringite were observed in

treated samples. These crystals weaved each other into clay particles

according to the scanning electron microscopic research.

The amount of these reactive products was quantitatively obtained by

X-ray diffraction intensities of pozzolanic reaction series and ettringite

series shown in Figure 7. In the figure, 0 , 0, , and 0 represent the

combination ratios 9:1, 8:2, 7:3, and 6:4, respectively. The distribution was

different from the types of stabilizing agents, and the least combination

ratio, 6:4, or the highest content of aluminum sulfate, produced the maximum

product of ettringite crystal.

X-ray intensity, 1CSH , 20 = 29.060, which is the main peak of CSH(1),

(II) and tobermolite, was clearly observed in the long curing periods of 360

and 720 days. This corresponds to the large increase in the q values shown

in ".- Figure 5. X-ray intensity of ettringite crystal, 1 ~~ett' 20 = 9.08, was "'''.

also observed in the long curing periods. As the excess free wateL was crys-

" talized into ettringite as seen by its molecular equation

3CaOA1 20 33CaSO 432H20 .7

244

I. - ' ." S
'; ° .

'To :360da ys

* o bnto ai P L)Cmiainrto(: ,")- ,'"-*

c(c

w,, :200% °'I M 1.

40 to

(}.5 •3,0.

0 20,

0 .

09 '. 1 8: 2 703 6 - 4 7 0

a. Wi 150%, To 360 days b. Wi = 150%, To 720 days

0. 5

0.3

04

: ~ -- --- 40 ,.- 0.3_ , " "'

o 0.

.9: 8:2 7:3 6:4 0

9 :8 820 4 ' '".' ".

c. Wi = 200%, To "- 360 days d. Wi ff 200%, To =720 days ,"-..'.

Figure 6. qu -" aw - CP:L)

245 

--

7 9 2 1 6 4" 0 0 z

9 2 7:

Comb nat on r tio omb P nati L n r tio P:

C. W 200, To 360daysd. W 20%, T 720day

Figur (P:L 6. u aw 

-***~*-.* i**-.- . A, ;~ 1< N. -. >1 : ,- - ~ ;-~~245-a
350 . o S: I group "

300

020 ~8:2 group

250

a 7:3 group

200Il

r.'...,

00 0

so 0

a 04 Soo 1000 1500 2000 2500

Ettringite-series lett (count)

Figure 7. I - I CSH ett

and the water content of the samples was arranged suitably, it is considered '-

that the pozzolanic reaction was accelerated. These results are shown in Figures 8 and 9 in relation to the amount of reactive products and unconfined

compressive strength. The increase in reactive products, ICSH' was directly

related to the increase in q value shown in Figure 8. The increase in

ettringite crystal, I was also connected with the strength increase shown

in Figure 9. The decrease in combination ratio 9:1 to 6:4, however, showed

the decrease in the strength in spite of the great products of ettringite ."-

crystal. This means that reactive products of ettringite do not directly correspond to the strength increase, but are related to it in inverse proportion.

If we tried to increase the ettringite product by enclosing free water, a decrease in the strength would occur.

Consequently, the lime-cement mixture treatment is recommended and the

optimum combination ratio is 9:1 or 8:2.

CONCLUSIONS

The hardening treatment of freshwater very soft clay soil formed by land

reclamation was introduced. The applicability of lime-cement-mixture was investigated in the laboratory. This special stabilizing agent aims at the pozzolanic reaction and ettringite product in order to solidify the very soft

clay soils by enclosing free water into its crystal. The hardening mechanism

was examined from the physicochemical point of view. -

246

V........,
0.0

/addition

1 / 1.0 () 0 30% addition)-"

0 A

00 

V 3/ d

0.5 -Z,-S

o / / ,0. 4) / 0.5 * 20% addition -

0_ 00 0

301 C/ r 0

* 0

S100 200 300 400 500 1000 2000 30..

CSH-series 1 CSH (COUnt) Ettringte-seres lett (count)

Figure 8. qu ICSH Figure 9. qu ~Iett

The results obtained are as follows:

a. The freshwater very soft clay soil used is mainly halloysite and

kaolinite minerals in suspension for a long time. Thus, the strength

due to self-consolidation after sedimentation is very small.

b. The hardening strength increases with the increase in the added volume of stabilizing agents. Trafficability on this soft ground is

obtained by adding more than 15 percent of the stabilizing agent.

c. The optimum combination ratio is 9:1 to 8:2. Beyond these ratios,

the effect of the ettringite crystal reduces the hardening strength.

d. The hardening mechanism was quantitatively shown in the reactive

products by X-ray diffraction analysis and scanning electron microscopic study. It was clearly seen that the pozzolanic reaction products are directly related to the strength increase.

BIBLIOGRAPHY

Japanese Soc. of Soil Mechanics and Found. Eng. 1980. "Testing Method of

Stabilized Soils Without any Compaction Work," Proc of Symp. on Testing'-

Method of Stabilized Soils, pp 15-18 (in Japanese).

Kamon, M., and Hamada, N. 1983. "Relation to Ettringite Crystal and Effect

of Soil Improvement," Annual Meeting of JSCE, Proc., Vol 3, pp 457-458 (in

Japanese).

Matsuo, S., and Kamimura, K. 1984. "The Study of Soil Stabilization with

Lime Type Additives," Tsuchi-to-Kiso, JSSMFE, Vol 32, No. 5, pp 5-9 (in

Japanese).

247

.- °€

• .. .. . . . . . .... " . .-.. ..-. ' % . % - . . .. - . ° . % % . %. ". % % " ° .. . ='% .%. ". - - " . %. . " % -
Taylor, H. F. W. 1964. "Appendix I, Tabulated Crystallographic Data, The

Chemistry of Cement," Vol 2, pp 347-402.

248
DEWATERING OF BOTTOM SEDIMENTS e...

Z. Yoshino, K. Sato, H. Okajima

Science University of Tokyo

Kagurazaka 1-3, Shinjuku-ku

Tokyo, Japan, 162

F. Kodama, S. Taguchi

Kasumigaura Work Office

Ministry of Construction

Tsuchiura, Ibaragi Prefecture

Japan, 311

R. Sudo, M. Okada .-

Laboratory of Freshwater Environment

National Institute of Environmental Studies

Tsukuba-Gakuen, Ibaragi Prefecture

Japan, 305

ABSTRACT

The properties and dewatering characteristics of

bottom sediments that had accumulated in Shinobazu

Pond and Lake Kasumigaura were examined. Comparative

studies were conducted using dewatering methods available to handle troublesome sludge. The continuous

vacuum precoat filter was chosen as the most effective

dewatering technique based on theoretical and experimental considerations. "."-

Field investigations at Ueno Shinobazu Pond and

Lake Kasumigaura confirmed that the continuous drum

vacuum precoat filter method is the best method

available for treatment of bottom sediments from both -

a technical and environmental viewpoint.

INTRODUCTION

In general, bottom sediments in closed bodies of water contain extremely

fine particles and colloidal substances which are troublesome to dispose of.

As the following equations show, the smaller the particle size x , the slower

the dewatering velocity u (-1/A-dV/dt). ..

For a gravitational dewatering process such as sand filter or dewatering

by solar drying bed:* '.*"

• See Notation at end of paper.

249 - . • * *° , -5." -

- " " -" " ."."." .".- o" " ." ' *5''' . .'- * e' * * '- ' .'-'. . " " . - " " ' . .. ' -. . S x ' - . ,
u - (I/A)dV/dt - c3/k'(1 - c)2(2/S)2pgAh/Ls . 8

W C3/k'(1 - c)4 WO2 (gAh/L1s

For a mechanical dewatering process such as pressure filter or vacuum

filters:

u - (1/A)dV/dt = e3/k'(1 - (S) p gc/I • L

-f e3 /k'(1 - e) 4 (x/) 2 Ap * gc/4 • L (2)

Figure 1 shows the particle-size distribution of bottom sediment measured

at Shinobazu Pond and Kasumigaura which demonstrates that very small particles

predominate with a small percentage of sand particles (Figure 2).

Figure 3 indicates the surface subsidence rate of the dredged bottom

sediments deposited in the solar drying bed at Lake Kasumigura from March to

-* July 1984. It can be seen that the dewatering rate is very slow, less than

0.4 cm/day.

2

Even if the area of solar drying bed is 70,000 m , the quantity of water

3 to be removed might be no more than 280 m /day. Therefore, the improvement of

an effective dewatering method has received considerable attention in the last

few years at Lake Kasumigaura and Lake Biwa in Japan.

The theoretical and practical considerations of dewatering methods have

been investigated for several years. The findings are reported herein.

FUNDAMENTAL CONSIDERATIONS

In general, the relation between filtrate volume V and dewatering time

t , i.e. a filtration curve, may be expressed by a parabola, as shown in

Figure 4, in accordance with the following equation: '- ,C.. .

t/V = (I/K)V + (2/K)V (3)

m

where.'

K 2A 2Apgc (1 - mw)/wuop

2 a. 2A Apg(I - mw)/Kw.-

3 32 f (I -) 3/ (I/p )k(/x)2 (4) s

V f AR (1 - mw)/awp (5)

From Equation 3, the following relation can be derived,

""~~ 1/2,.., ~ 

V/t + V /t = [K(l/t) + (V /t)2] (6) m25m

" ~~250 .,.,.
1%(1XYUK -.A.

0~~ ......

0 20 40 60 80

X, Parlicip $121 I)pfi .

0 vs. X

Figure 1. Particle-size distribution of bottom sediment

- ~ ~ .

~~~~ ENS--~*

.*~*-. IV

S ~ b Fgre 2.ZLk E asmgua.

-. ~ ~ ,*. ~ *kr ~~~: ,..f .*<

Botm eimn

* Usall, te reistnceof flte meium ismuc smalertha th

m.

IRK-

-Aw -

J25

................ A d . .* ..

**.-.a. ~ Sh no ~ az ~* Pond . . . . b*** .. Lak .. * . .. *.** . -
2.4

4b'

20 JI * 0 0 0 0.

.P

I-iW

Figure 3. Subsidence of surface of the dredged bottom sediment.,-

(Kasumigaura)

C.ONTINUOUjS V.%=10'4

trifTATO4 UA=CIWISE PREss~fl rELTzom

1.L riltnr Automatic fiter-press Pressure filter Fite press

~.- with

40 (Exp~ression

4D

0 I

0 S 1 2 3 4 S 7

Filter cycle time:t,(hr)

Figure 4. Filtration curve and dewatering apparatus

The slopes of the dotted line in Figure 4 and Table 1 provide a compari-

* son of the filtration rate of conventional dewatering methods; the continuous

* vacuum drum precoat filter is seen to be the most effective dewatering technique from among the conventional processes.

EXPERIMENTAL APPARATUS AND PROCEDURES

Fundamental experiments and investigations on the dewatering character- .

istics of various bottom sediments were conducted with (a) the batch testing

apparatus using a vacuum filter (Figure 5) and a pressure filter, and (b) the

small-scale continuous vacuum filter (Figure 6) at Science University of

Tokyo, supported by the Ministry of Education, Japan.

252

.. '. L
r C..~. 7..- 77 WT-' .T- MTC M' NC~t. -. N* V

TABLE 1. DEAEIGPROCESS AND CYCLE TIME OF SEVERAL

PROCES Gavia nL onaorn Youm riLtratia. ftwoue titraton Cetiual0 trn

Las locculiation Satehwtv Cotnuu Sthwiue PROCESS 1

"6Seam filter AUIOU.Z.,tiou,

CYCLE TIE several days ~ * -

several tens of days C- (Chte

sd.d)trim lit ay. 

hra. 

aif . it 

cakire -s.elih.

Dq~~~e lof5 teri ime

raail ~~rn ~ck -gaj a" iilt

Dosoigte Us toaarn t hr.aela

Dewteing ta In--in.

cak .5aeig ae' f a fi

Dowatering~~h tisIsi.Ion.

Shinobazu~~~~~~~~~ PnwthtecniuuvaumpcotFilterec(srfcarao

0.5~~~~ in)(iue7MrmJnurooMrh18 n ithr thep cotnosvcu

precoat~~~~~~~~~~~ fitr(ufcVraof2i 2 Fgr )acuu LaePumi uafo

Januar toaJulm1984

~~~Figure lsrtshE . otie hxperimental planttu employed at

Kasoiaulwihes constaitdos clariie tou emoel th eraetio and

Sioaunwihthe continuous vacuum precoat aste(ldgsuwtrrfaceredged filter 

material isic pupeconsithedoa clarifier byasurymv to pump sand frtoseparad

*to remove sandy material, and then flows into the filter tank in Figure 9.

253 '' *
IFeed tank

© 6 srao~r

E77i>o® Fi/J:)t @c

0 a~~~1 )M~vacn t

Figure 6. Exeimn a* apaus cntnosoe

'L ~.Z. ~!J%

Figue7.CoFingue 6.Epuumena Figraue (.continuoumovcume)cot

precoat-filter dewater- filter devatering the

ing the bottom sediment bottom sediment of Lake

of Shinobauu Pond, Kasumigaura, Ibaragi

254
-a- . I

Slurr Dp

1 ClarifierSHed tank

1 Surry pu-P

Filtrate pump

I PFate# receiver (D)

Figure 9. Experimental plant situated on Lake gasumigaura IRS'.

The thin cake formed on the precoat cake of filter aid, e.g. diatomite or ...,.

pearlite, is removed by the advancing knife (D while the clarified filtrate,',-..

is pumped back to the lake. 0'%i.°

EXPERIMENTAL RESULTS AND CONSIDERATIONS

Dewatering Characteristics .'

Figure 10 indicates the relation between filtration pressure Ap and ., .".

spcfcresistance a of various bottom sediments measured by the Leaf-test -

____

mentioned in Figure 6. i a a i d L a g

It was found that these sediments were very difficult to dewater byi

conventional dewatering processes such as filter press, belt-press, and/or. -..- solar drying bed (Table t) becaus kfe extremely high specific resistance **'

and excessive compressibility (Figure 10"

Recovern of Sand Materials *' -- '

Figure 11 illustrates the particle-size distribution curve of the settled .

fraction from each stage of the clarification process shown in Figures 9..--"

It was confirmed that sandy materials could be easily recovered by the

specially designed hydroseparater, with a retention time of about 0 min.

Filter Capacity..'"":

IFigure 13 indicates the filtrate capacity of the continuous vacuum

precoat filter facility. It was found that even vr troublesome dfu toe sediments eb could 

be efficiently dewatered. Filtrate capacity was approximately 0.7 mand/or

for the bottom sediments of 10% solid content, and 0.3 ms/M/hr for sediments -

of 30% solid content.

255"-'""

It sady ws cofirmd mterils tht culd e eaily ecovred y th

,- ..-. specially... designed- hyrsprtrwt . .... . . eeto . time of. about - 10 .m, ,.--. . ,,-. .--.- "
40- Mrr MIR

0Idaf I~ .,*pUNN

~3.0-

I2.0

0

0 0.1 Q2 0.3 Q4 Q5 Q6 L7 Q.8 Q9 APFiltration pressure Cligicm2

Figure 10. Specific resistance of bottom sediments

150

n.otll I nio 41mIs

Figure 11. Particlesize : ditibto ofstldsld

% Since the slope of the dotted line expressing experimental results is

about -1/2, the fundamental equation (7) is applicable to these dewatering

phenomena and can be represented by the following equation, corresponding to

the relation shown by Figure 14.

S-V/CA* t) h4 K *w" * t/ (8)

256
-M -S - -.- 6.S , 

Feed1 d stage 4th Stage OverfL OW

lot stage 3rd stage

Figure 12. Schematic of clarifier

I0- i5 103 10g-- 16 .4....

A 2

,...,.-~

A -A b

102 4 -

10 A

0.1 1.0 10

Figure 13. Filtrate capacity of continuous precoat

filter for the bottom sediments of Lake

Kasumigaura (tc is cycle time,

m.p.r. - min)

Effluent Concentrations .Filtra

Filtrate discharged from the continuous vacuum precoat filter was clear

enough (10 mg/t suspended solids) to be pumped back to the lake and/or reused

as process water.

Moisture Content of Cake

Moisture content of the cake removed from the continuous vacuum precoat

filter was less than 50%, and therefore eligible for disposal or reuse as a .

257

* C* ~* ' **A *-, ...-.......,-,.
10 I

sfW(1 V5 tc

E

, - -% 

1 0 1.0 10

t m.p.r.)

Figure 14. Sf W 1/2 [g1/ 2 /L1 /2 . m 2 . hr]v.s. t [m.p.r.]

fertilizer without any difficulty. In addition, since the cake was very thin

*(less than 1.0 mm), it could dewater until the moisture content wan 35% by

subsequent solar drying, during 1 or 2 days as shown by Figure 15.

CONCLUS IONS

The following conclusion can be drawn from this study:

a.The properties and dewatering characteristic of various bottom

sediments were examined, and it was found that these sediments were very

difficult to dewater by conventional methods because of the extremely high

specific resistance and the excessive compressibility.

b. The sandy materials contained in the sediments were easily recovered

* by the hydroseparater.

c.Comparative studies were made on a dewatering process available to

*such troublesome sludge, and the continuous vacuum precoat filter was chosen

as the most effective dewaterer by theoretical and experimentalw

investigations.

d. According to field experimental investigations at Shinobazu Pond and

*Lake Kasumigaura, the following data have been extracted:

258

• t,... .-- -. .. . . . .. *.*-."* * *
•. .r

(1) These troublesome sediments could be efficiently dewatered with

the continuous vacuum precoat filter.

(2) The filtrate capacity may be expressed by the following equation:

S = V/(A . t) - K . w 2 t

(3) Filtrate discharged from the continuous vacuum precoat filter had

suspended solids concentrations as low as 10 mg/i, clear enough

for pumping back into the lake or reusing as process water.

(4) Moisture content of the cake removed from the continuous vacuum .'-,*V

precoat filter was less than 50%, and therefore eligible for

disposal or reuse as a fertilizer.

e. From the theoretical and experimental investigations, the continuous

vacuum precoat filter may be the best method available for the treatment of

bottom sediments from both a technical and an environmental viewpoint.

ACKNOWLEDGEMENTS

We are very grateful to Mr. Yasushige Kobayashi and Shiro Suimatsu, Tokyo

Metropolitan Government. These investigations were largely supported by a

Grant of the Ministry of Education, Japan.

740 -

630"

20 I

10,

I III I , r .- .

"29 30 31 1 2 3 4

Mar Apr.

13:00.'

Figure 15. Dewatering curve of the filter cake by solar

drying (M.C. -moisture content)

259
- 1W :- Z '7j -

NOTATION

A Filtration area cm2 or m2

k Empirical constant -.

K Filtration constant m2 /sec

m Weight ratio of dry cake to wet cake --

g Acceleration due to gravity cm/sec2 ."

9 Conversion factor kg.m/kg.sec2

L Depth of filter medium cm or m

2 3 S Specific surface area cm /cm

2 Sf Filtrate capacity Z/(m .hr)

t Filtration time sec or hr

t Filter cycle time min or hr

c

m3 c 2 ,--"

u Filtration velocity cm / sec --

V 3 3 -.- Volume of filtrate cm or m

V Imaginary filtrate volume corresponding

to the filter medium cm or m

w Solid content g/t or kg/m3 -

x Particle size Um or cm

* Specific cake resistance cm/g or m/kg - ...

&h Head cm or m

Ap Filtration pressure kg/cm 2

e Porosity

Viscosity g/cm.sec

p Density g/cm 3

Shape factor

260
BIBLIOGRAPHY

B. F. Ruth; Trans. Am. Inst. Chem. Eng., 33, 34 (1937); Ind. Eng. Chem., 25,

76 (1933), 27, 708, 806 (1935); 38, 564 (1956).

Yoshino, Z.; KAGAKU KOGAKU, 30, 205 (1966).

Yoshino, Z.; Ibid., 35, 91 (1971).

Yoshino, Z.; Industrial Water, No. 171, 10 (1972).

" Yoshino, Z.; KAGAKU KOGAKU, 37, 431 (1973).

Yoshino, Z.; Ibid., 41, 88 (1977). .

Yoshino, Z.; Inter. Chem. Eng., 11, 547 (1971).

Yoshino, Z.; KAGAKU KOGAKU, 43, 130 (1979).

Hiraoka, M.; Annual Report of Studies on Sludge Treatment (1980).

Steering Group of Special Project Research on Detection and Control of

Environmental Pollution, Supported by the Ministry of Education, Japan;

Chemical Engineering for Water Pollution Control, Vol. 3 (1979).

Yoshino, Z.; Industrial Water, No. 257, 61 (1980).

Kagaku Kogaku Kyokai; Treatment Process and Apparatus of Sludge (1978 in

Japanese).

Hiraoka, M.; Annual Report of Studies on Sludge Treatment (1981).

Kagaku Kogaku Kyokai; Dassui-shori Gi jutsu Chosa Hokoku (1981, entrusted from

Tokyo Metro.).

Clean Japan Center; Sai-shingenka gi jutsu, Dassui (1981, supported by the

Ministry of International Trade and Industry, Japan).

Yoshino, Z.; KAGAKU KOGAKU, 45, 89 (1981).

Yoshino, Z.; Ibid., 45, 423 (1981).

Yoshino, Z.; Industrial Water, No. 286, 9 (1982).

Hiraoka, M. and Yoshino, Z.; Odei-Shori-Kogaku (1983, Kodan-sha).

261

""26 . . . . . . . ..-... .*.**-..*.-*..

N . .° - " •.." ]
* . I ""' "

FLOW PROCESSES OF A CUTTERHEAD DREDGE*

L. S. Slotta

President, Slotta Engineering Associates, Inc.

PO Box 1376

Corvallis, Oregon 97339

ABSTRACT ...

Feasibility studies of new dredge intake and cutterhead shielding techniques were conducted to improve

hydraulic cutterhead dredge performance. Simple modification of the suction mouth to the intake piping and

utilization of both internal as well as external

dredge cutter shrouds have been found to significantly

improve the production of a cutter suction dredge

model.

INTRODUCTION

In sustaining the nation's navigable waterways, the Corps of Engineers

annually dredges over 400 million cubic yards in maintenance dredging operations and over 200 million cubic yards in new work dredging at a (1976) cost

over $150 million. Much of this work is contracted out competitively to independent dredgers. Surprisingly, dredging work is difficult to obtain as the

work is spread seasonally and spatially Into small work packages. The result

is that about half of the U.S. contractor-owned dredging fleet is idle at any

given time. With a bleak economic outlook, the private dredging contractors

are unmotivated to upgrade and modernize dredging equipment to operate more

efficiently or to reduce environmental impacts caused during dredging operations in rivers and estuaries.

National Science Foundation-Small Business Innovative Research support

was received for investigating the economic effect on dredging production of "

cutterhead dredges through simple design modifications such as adding cutterhead shields, making minor changes to the cutterhead form, and properly

placing the suction inlet relative to the cutterhead rotation. The ultimate .

goal was to provide the dredging industry with cutterhead and suction inlet

design concepts that would increase the excavation and production efficiency

of hydraulic cutterhead pipeline dredges, and accordingly reduce objectionable

turbidity currents frequently created by dredges operating in waterways.

• Permission to reprint was granted from the American Society of Civil Engineers who first published this paper in the PROCEEDINGS for DREDGING 84, a - -

specialty conference held in Clearwater Beach, Florida, November 14-16,

1984.

262
Computer model simulations were used to investigate the processes of soil

movement and transport by a confused three-dimensional flow field affected by -

complex boundaries, rotating cutterblades, variable flow rates, and positioning of the intake to the dredge pump. Rotational speed, haul velocity, depth

of suction inlet, and cutterhead shielding techniques were verified and tested

during hydraulic model simulations. Suction inlet types, internal codes, and

external shields utilized in these feasibility studies are shown in Figure 1.

..

Figure 1. A: crown-shaped cutter (1:6 scale, 19-in, diameter,

16 in. long; B: crown-shaped cutter (1:12 scale,

9-in, diameter, 6 in. long); C: dog-eared cutter

shroud; D: half cylinder inner core; E: 45-deg.

beveled suction mouth; F: long beveled suction

mouth; G: small reentrant suction mouth;

H: 12 bladed cylindrical cutterhead (1:12 scale,

9-in, diameter, 6 in. long)

For both computer model and hydraulic model simulations, a cylindricalshaped disc cutter was utilized as a basic model. Evaluations of the cylindrical cutter can easily be extended to basket type cutters. The characteristic feature of the cylindrical shaped disc cutter (Figure 1 ) is the

potential optimal positioning of the suction mouth which extends into the

interior of the cutter towards the rotating blades. High suction velocities

to a reentrant suction mouth would reduce the recirculation of the soil

cuttings within the cutterhead's crown. This suction mouth can be turned

towards the direction of cut to improve the inflow to the pump intake.

COMPUTER CODES

Complex computer codes recently made available by CHAM Ltd. (Concentration, Heat and Momentum Limited, Bakery House 40 High Street, Wimbledon,

London SW195AU ENGLAND) and CREARE R&D, Inc. (CREARE R&D, Inc., P0 Box 71, . .- +

263

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

potentia optima positin.ng.o..he.suc.on..ouh.whi.he.tendsinto..h
* -- -- --. _

Hanover, New Hampshire 03755), provide three-dimensional results of turbulent

two-phase flows past moving boundaries. Sediment transport into the moving

blades of rotating dredge cutterhead was simulated using both CHAM Ltd.'s

PHOENICS and CREARE R&D Inc.'s FLUENT codes.

CHAM Ltd.

CHAM Ltd. developed a software package designed for the simulation of

fluid-flow, heat-transfer, mass-transfer, and chemical-reaction processes. It

is called PHOENICS, which stands for Parabolic, Hyperbolic or Elliptic Numerical Integration Code Series. In the parabolic form, effects do not propagate

upstream; in the elliptic form, effects do propagate upstream; and in the ' .

hyperbolic form effects propagate along "characteristics."

PHOENICS uses a finite difference numerical procedure to solve the fundamental equations governing fluid flow (the Navier-Stokes equations). Built

into PHOENICS are the major laws of conservation: the mass of each present

phase, the three components of momentum for each phase, the thermal-energy

contents of each phase, the mass concentration of each chemical species, the ,..-

energy and length scale of the turbulence, and the fluxes of radiation. The

equations include individual terms expressive of the processes of convection,

diffusion, generation, and destruction, and appropriate accounting of the

interactions of turbulence with the laminar-flow phenomena.

With CHAM Ltd.'s PHOENICS code a cylindrical model was numerically

created to repreqent a simplified dredge cutter having four blades or arms.

Figures 2-5 are representative of these PHOENICS graphics. Figure 2 is a perspective view o a rotating four blade cutter with a velocity field located at

one tenth the cutter length. The outflow of water to the suction mouth

located at the 6 o'clock backplate position is clearly represented. Figure 3

shows an end view of the cutterhead, orthogonal to the drive axis and cutter

blades. The rotational velocity field about the blades accelerating into the

suction mouth illustrates some of the flow representations possible with

PHOENICS graphics routine. Figure 4 is a perspective composite of the previous information, including: cutterhead shape, blade position, velocity field

near the backplate, and the flow paths of particles released at "tenth" positions long the top of the cutterhead. Superimposed on Figure 5 are the flow

trajectories of particles cut from the 12 o'clock position.

The PHOENICS code utilizes an Eulerian approach in which the fluid density in a cell of a computational grid is uniform and continuous. However,

the density in an adjacent cell can be designated as having a different value,

thus allowing for two-phase flow calculations.

The two-phase flow test representation used a submerged vertical suction

pipe held above a sand bed. Figure 6 shows the sediment velocity flow field

on the right while sediment volume fractions are presented on the left. By .p..

examining the break in the sediment volume fractions one observes the zone of

sediment pickup into the suction mouth. These results are being analyzed in

reference to previous physical model data on the threshold pickup zone of sand

taken into a suction intake (see Figures 7A (Reference 4) and 7B (Reference 2)). The results show similarities to potential flow techniques and

physical measurements reported by Salzmann (3) and Brahme (1). In Figure 8

264

F,

" % , "" '
A N

Figure 2. Cylindrical dredge cutterhead flow simulations,

perspective view

11/1 SUCTION MOUTH

\ .11- AT 6 O'CLOCK

* I.,\( ' - - / IN BACKPLATE

Figure 3. Cylindrical dredge cutterhead flow simulations, **4*%

end view

265
Fiur 4.Clnrcldeg uteha lwsmltos

compsit

ARTICES OCLOC CT AT12 

SUTINMOTHA

Figure 5. Cylindrical dredge cutterhead flaw simulations.

copositectre

- RTCLS U A216OCLC

/.
I 

ENV

I

3N

SEDIMENT VOLUME VELOCITY VECTOhS -'.-. FRACTIONS

Figure 6. Sediment pickup simulation, sediment volume factions • on left and water velocity vectors on right

the velocity and pressure field of flows up a 0.6-m (23.6-in.)-diam intake '---- tube with 0.03-m walls is represented. The flow is created by a negative.-,.

pressure of one atmosphere within the intake pipe. For the sake of symmetry, -:-,,,

water phase velocities are shown on the right while the pressure drops asso- '

ciated with the flow are shown on the left.

CRAM Ltd.'s staff believe PHOENICS can properly simulate sediment trans- \"''

port with the density continuum approach. A sand bed might appropriately be "'.:-

represented by a volume fraction in each grid cell of 0.6 solids and-.:.:?

0.4 fluid. Transient flow simulations using PHOENICS of the loosely packed -, soil revealed the bed to progressively settle with time under the action of

gravity. In actuality, such a bed would remain rigid through granular interactions rather than collapse. As these computational studies are preliminary, ,''.

plans have been made to continue to evaluate this code for properly repre- ... : senting the physics of sediment transport. "'"

CREARE R&D, Inc.

CREARE R&D, Inc., has developed a competitive, user-friendly, general .i.. purpose computer program for modeling fluid flow called FLUENT. FLUENT is made accessible to the user by means of an interactive menu-driven interface' ---; " --. 

"- .-; Z.°

for problem definition, computation, and powerful built-in graphics. FLUENT...-.

enables the fluids engineer to apply state-of-the-art computer simulation

methods to analyze and solve practical design problems without costly, time- -'-'-, consuming programming. " '-'

FLUENT uses a finite difference numerical procedure to solve the funda- " " mental equations governing fluid flow (the Navier-Stokes equations). Addi-I -' . tional equations are solved for the conservation of the parameters of the k-e

turbulence model, chemical species, and enthalpy. Their numerical techniques

involve the subdivision of the domain of interest into a finite number of ""

267
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4.144

14'

-~~ 0 00

4.-.

00 -d -

0 414

kaf 04 3 1~ U

0 r04C4

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III

."

SEAATO GA105' . j.. • . . S .

SEPARATION GAP = 0.5 M -- SAND BED 1670 KG/M3

- o-,,.- ,. .b

PRESSURE VELOCITY VECTORS

DISTRIBUTION -

Figure 8. Sediment pickup simulation, pressure distribution

control volumes or cells, the partial differential equations being discretioned over these cells to obtain sets of simultaneous algebraic relations.

Presently FLUENT is programmed only for solving steady flow problems. The

FLUENT code conveniently incorporates a Lagrangian method for utilizing marker

particles of various grain sizes and densities. This is most useful for portraying sediment transport through dredge cutters as shown in Figures 9A to F.

A present limitation of the FLUENT scheme is that particles cannot be assembled as a bed, but can only be introduced singly at a point or in a layer

through a desired boundary.

FLUENT dredge cutterhead flow simulations are depicted in Figures 9A to

F. By considering symmetry, only the left half of the cylindrical cutterhead

was plotted and, for clarity, the cutter blades were omitted. A range of soil

particle diameters and densities was cut at different positions on the rotating cutterhead and the trajectories were plotted. The flow field vectors, as

seen on a vertical plane below the axis of rotation, pass through a segmented

- gap in the backplate (Figure 9A). Figure 9B shows the trajectories of light

particles (p = 1670 kg/m 3 ) released from the 12 o'clock position of the rotat-

* ing cutterhead with a 45-deg angle; one particle is noted to enter the suction

mouth. Figure 9C represents the trajectories of a range of particle diameters M

having a constant (p = 1670 kg/m) density, which are released at the twotenths length position at 12 o'clock; nearly all the grains escape. Figure 9D

represents similar conditions but the particle release point is midway along .,.-

the cutter length; note only two particles escape while the others are trapped

to recirculate about the crown of the cutter. Light (Figure 9E) and heavy

(p = 2670 kg/m) (Figure 9F) particle trajectories are shown for release

269
161670 kg/rn

FLOW FIELD VECTORS dp s 1003. 0.03 m vo

000

* - ... -....

o* o,. .o o

stop 0.0015 stop, .0.0015

,. .1 ....-

p a 1670 kg/m p a 2670 kg/r'3

d z. 0005 m dOa 00 2.

step 0.0015..55.. .

Figlure 9. Perspective view of cylindriceal dredge outterhead flow -

simulations. Suction mouth at 6 o'clock in bookplate ,.,-..

270 k/ .-

d .0.00-..d-.0.005

. . . . .. . .. . ' -- :'*:

. . . . . *.,........ .. , .. ... . . -.-.---.......-,. .,,.,._, . , , .,,,,,...

.---....'. ,............'... ..- .. .. ,..... .. ..... .. . . . . . . .] ;.. 
points near the 8 o'clock digging position. The light particles are nearly

all drawn out the suction mouth whereas the heavy particles are not as successfully drawn into the intake.

Summary

In summary, both the PHOENICS and FLUENT codes have exceptional three-

*, dimensional graphics for representing hydraulic and hydrodynamic phenomena.

User-friendly computer programs for solving complex three-dimensional flow

fields involving gravity, viscosity, turbulence, and difficult boundary con- Mir

ditions of inflow and outflow are becoming available. Problems, previously

intractable by analytical or numerical techniques, are now solvable. The

results gained in these dredge studies show that these hydrodynamic codes are

at a stage corresponding to the stage where finite element structural dynamics

codes were ten years ago.

For these studies, it would have been desirable to represent a submerged

"* static soil bed that did not collapse over time and that was not limited to

having only a single layer of particles accessible for transport. Perhaps in -

the future, such user-friendly hydrodynamic codes will be refined to properly

represent sediment erosion and transport.

HYDRAULIC MODELS

A 1:12 hydraulic model test facility (Figures 10 and 11) was utilized as

a beginning step to validate the numerical models as well as to examine improved dredge cutter performance using simplex modification to the suction

inlet. A 0.23-m (9-in.)-diam cylindrical-shaped disc cutterhead model having

a depth of 0.15 m (6 in.) was used to compare basic parameters, including:

angular rotational speed, haul velocity, ladder angle, and position of the

suction inlet. The model cutterhead was mounted on an adjustable ladder connected to a frame holding a 1/8-hp gearmotor with a speed controller and a

18.3-m'/hr (0.18-cfs) pump. The rim of a 3.04-m (10-ft) by 0.91-m (3-ft)

stock watering tank served as a track for four castor wheels under the carriage (Figure 10).

Masonry sand with a mean grain size diameter of 0.5 mm (0.02 in.) was

hardpacked with the intent of representing hard digging of consolidated sediments and to ensure reproducibility of results between runs. To consolidate

the sand, a concrete-cement stinger or vibrator was first used for fluidizing

the bed. Three 0.03-m (1.25-in.) perforated polyvinyl chloride (PVC) pipe

units were interconnected and placed at the bottom of the 0.61-m (2-ft)-deep

oval holding tank. Nylon netting was laid down over the pipe to prevent sand

intake to the pipes. A consistently hard sand bed was prepared for each run

by connecting the dredge pump intake to this network and running the pump for

20 min. Dense compaction of the sand was checked prior to excavation runs.

The cutter production tests were run with haul velocities averaging

0.14 ft/sec (4.19 cm/sec) and average rotational speeds of 48 to 96 RPM. The

average velocity in the 32-mm (1.25-in.) suction mouth delivery line was % , 3.2 m/sec (10.5 ft/sec). The ladder inclination angle was set at 45 deg for

all tests.

271

-. .*. ,. . . . . . . . .. . .. .- . . ** . .,..,-
II

'A.

Figure 10. A 3-u-long cutterhead dredge teut

facility with water partially

drained for viewing tracks of the

dredge cuts

The hydraulic laboratory studies confirm that extending the intake pipe

within the dredge cutter will significantly increase most hydraulic dredges'

production. Tests compared: (a) plain suction mouth, (b) long extended

mouth, (c) 45-dog beveled mouth ("looking down"), (d) 45-dog beveled mouth

with an internal cowl and a dog-eared external shroud. and (e) 45-deg beveled

mouth with a dog-eared external shroud (Figure 11). Overcut and undercut mods

results are plotted in Figure 12. Cutter speeds are shown as a percentage of

full speed of the drive. Accordingly, 100 percent corresponds to 160 RPM;

50 percent to 80 RPM; 40 percent to 64 RPM, and 30 percent to 48 RPM.

Hydraulic model suary results (Table 1) show that maximum production

was observed in the undercut mode at 48 RPM and when the 45-dog beveled mouth

and external shroud were used. The 45.5 percent solids by weight concentration corresponds to a 24 percent solids by volume discharge. This production

is quite impressive when compared to that achieved by most operational

dredges.

272

r . . .
Figure 11. Cutterhead carriage tilted to allow examination

of dog-eared cutterhead shroud, half cylinder -'-

internal cowl, and extended 45-dee beveled '*'* suction inlet ~''

CONCLUS IONS

This research involves both three-dimensional numerical analyses and ....

hydraulic model studies of rotating machinery involved in submerged sediment

excavation. These hydrodynamic codes were shown to have the promise of '.--

properly simulating complex, three-dimensional, rotating flows conveying water °.'''

and sediments through dredge cutterheads. Hydraulic modeling showed that simple modifications to the suction intake and the addition of dog-eared external --. '

cutter shrouds and internal cowls gave marked increases of dredge production. .-.-.-

The results of more extensive confirming investigations could be used to "'-'" encourage private contractors to easily and economically adapt their equipment. '-'":--

to increase their dredging output, and in the course of operation, to reduce - dredge-caused turbidity in the waterway being excavated.

These investigations, particularly those advancing the use of numerical...-.-

hydrodynamic flow simulations, could also assist in the development of a ."i

broad-based methodology for more scientific studies of drilling, tunneling,•.-

and dredging equipment than that which has been previously available. O

ACKNOWLEDGEMENTS "

•

•-

The material herein was gained through work supported by the National ... ..

Science Foundation under award number MEA-8360994. Any opinions, findings, ..-.

and conclusions or recommendations expressed in this publication are those of

the author and do not necessarily reflect the views of the National Science }iiiii

273.

,:o :.?" i-: ,..:.-: - i..... ." :- :";-#---.:-: :-:":-.-:ii-'.-:,-:. - i :-::-.:-Y- .?'..'.:'. i-'-'.--t-.°¢;-' : .::."." . ..:. °" -';-. ; .'-.;i __ .' .
A. OVERCUT- II

40

~30

20 %

10 20 30 40 50 60 70

CUTTER SPEED (% RPM)

I..

B. UNDERCUT

450

30

20 -

10

I I I4

10 20 30 40 58 68 7

CUTTER SPEED (%RPM)

rk LEGEND

-- PLAIN SUCTION MOUTH INTAKE

.LONG MOUTH

-~-45-DEG BEVELED MOUTH

BEVEL, SHROUD, COWL

. BEVEL, SHROUD

Figure 12. Plots of maximum production (percent solids

by weight) and cutter speed for different

shroud, cowl, and intake conditions -

274

Lo

: ; . ... : . ,-'- **...1
'C TABLE 1. HYDRAULIC MODEL RESULTS

Maximum Sediment Increase in Production

Suction Mouth Production, Percent Relative to Plain

Inlet Solids by Weight Suction Mouth, % .. -.

Overcut--48 rpm (30%) ,-.. .

Plain 11 0

Long mouth 29 160

45-deg beveled mouth 36 225

Bevel + shroud 36 225

Bevel + shroud + cowl 41 227

Undercut--48 rpm (30%)

Plain 30 0

Long mouth 30 0

45-deg beveled mouth 34.5 15

Bevel + shroud 34.5 51.7

Bevel + shroud + cowl 41 36

Foundation. NSF's support is gratefully acknowledged. Interest and communications on this project with Dr. John Weese, Director of NSF's Division of

Mechanical Engineering and Applied Mechanics, have been gratifying.

Dr. C. M. Aldham of CHAM, Ltd., Wimbledon, England, is thanked for cooperative programming of PHOENICS hydrodynamic code results presented herein.

Dr. Sengal of CHAM of North America, Huntsville, Alabama, worked on two-phase

flow representation using the PHOENICS code and his efforts are gratefully

acknowledged. Ms. Barbara Hutchins of CREARE R&D, Inc., of Hanover, New Hampshire, is thanked for programming the FLUENT code for particle size trajectories through a rotating dredge cutter.

The staff of SEA (Slotta Engineering Associates) are thanked for their

help in seeing this work completed in a professional and timely manner:

Ms. J. Milbrat did much to organize the report, Mr. T. Callahan conducted the

dredge head lab tests, and Mrs. S. Shribbs did a most commendable job in

typing the text of the paper.

Thanks are extended to ESCO Corporation, Riedel International, Inc., and

DREDGEMASTERS International, Inc., for their continuing interest in dredging

research.

275

'.'.' ,'.. ".,. . ... ' , - ' ,. " ' , . . . . . . . .. -.. .- . -- .- . -" . - . ':. . . -.- .. . . - .,. ,., *... . .
116

REFERENCES

1. Brahma, S. B. 1983 (Dec). "Environmental Aspects of Suction Cutterheads," Thesis, Texas A&H University, College Station, Tex.

2. Gladigau, L. N. 1975 (Feb). "An Appreciation of the Scale Effects of

Solid/Liquid Flow in Dredging Studies," Thesis, University of Adelaide,

Australia.

*3. Salzmann, H. 1977 (Feb). "Fluid and Soil Mechanics Processes During

Hydraulic Dredging," Franzius-Inatitut, Hannover, West Germany, (David R. . .O

Basco, Technical Editor, Translated by Gertrud N. Adam, Texas A&)1 University, College Station, Tax.)*

4. Slotta, L. S. 1968. "Plow Visualization Techniques Used in Dredge Cutterhead Evaluation," Proceedings of WODCON '68 held in Rotterdam, Holland,

published by World Dredging Conference, Palos Verdes Estates, California,

pp 56-57.

276
~.. '- .

SELECTION AND MANAGEMENT OF A NEW OCEAN DREDGED MATERIAL ..-.-

DISPOSAL SITE AT COOS BAY, OREGON, USA, TO RECEIVE

CONTAMINATED DREDGED MATERIAL

J. R. Reese

Portland District, Corps of Engineers"- 

P.O. Box 2946 ,

Portland, Oregon 97208 -

ABSTRACT

Ocean disposal of dredged material on the Pacific

Northwest coast has, until recently, involved only

clean, medium-grain-sized marine sands. Those sediments are dredged by hopper dredge and placed at

approved interim ocean disposal sites in the littoral

transport zone directly offshore from the estuary.

The upper reaches of those coastal river systems are _

normally maintained by pipeline hydraulic dredges and

the material placed at upland disposal sites. The

material is a silt clay sediment, and in Coos Bay is

considered slightly contaminated by existing Federal

criteria. Upland sites are becoming extremely difficult to obtain and at Coos Bay, Oregon, all approved

sites are nearly filled to capacity. The only alternative to upland sites is transporting material to the

ocean. Portland District determined that upland sites

at Coos Bay would be filled by the early 1980's, and

in 1977 proceeded with long-term oceanographic studies

for evaluating ocean disposal sites to accept finegrained, slightly contaminated dredged material. The

District recognized that the site and sediment must be

in compliance with State and Federal regulations,

especially the Marine Protection, Research, and Sanctuaries Act. Chemical, physical, and biological studies were conducted for 2 years on nearshore ocean

environment and dredged sediments. This led to proposing a site, followed by test disposal operations to

verify predictions on transport and ultimate fate of

the material. This paper reports on establishment of

research, basic assumptions made to locate a new site,

and the management decisions necessary for final

selection and evaluation of the proposed area.

INTRODUCTION

The Portland District, U.S. Army Corps of Engineers, is responsible for

maintaining coastal river channels in the State of Oregon. Approximately

6.7 million cubic meters of sediment is removed from 12 coastal river channel

277
,- m...,-.

entrances each year. These channels and harbor entrances are shown in Figure 1. The two coastal projects where the majority of dredging is performed

are Columbia River and Coos Bay. The mouth of Columbia River requires removal

of approximately 4.6 million cubic meters annually and Coos Bay 1 million

cubic meters. Coos Bay dredging and disposal is the topic of discussion in ,"

this report.

Coos Bay is a large industrialized estuary, second only to the Columbia ' " '

River in size and importance to Oregon. The estuary, as shown in Figure 2, is

*. roughly 4047 ha in size and drains a total of 1567 sq km. Approximately

4 million tons of forest products are shipped through Coos Bay navigation

channel annually to Far Eastern and European ports. Since 1951, Portland District has been engaged in maintenance and new work dredging to ensure depths

suitable for medium-draft (9.14- to 12.2-m) vessels. The channel is 10.36 m'

deep and 24.14 km long and extends from the Pacific Ocean up the Coos River to

the head of navigation in Isthmus Slough. Figure 3 shows the channel and

general features of Coos Bay.

C D .s T R I C T

c ,? NORTH PACIFIC

i.

71 MV:s;CZi Scol In Kilomters ' %.

0 1 -_.00 

,. .. . 'Sc . 0. S 7.. - N I V

'A I . S A CI A ME N 7 0 1 S R . -A

Figure 1. Location map

278

"- - -_ _ - - - > " - / ,t. "%
.. .-- Q'%T. 7 W . M I W- W 4 . -

OREGON .. COOS BAY

CALIFORNIA NEVADA ,

.~~. ..- . ...

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

Figure 2. General features of the Coos Bay estuary

Hopper dredges historically have maintained the navigation channel from

the entrance to river km 19.3, and pipeline dredges have been used in the

upper channel. Hopper dredging accounts for 688,140 cu m annually, and pipeline dredging of river km 19.3 to 24.14 generates 382,300 cu m. The upper bay r

dredging has traditionally been deposited in upland or in-bay disposal sites.

A 1975 Environmental Impact Statement (EIS) for new work dredging at Coos Bay

(8) determined that all available upland sites which complied with environmental regulations would be filled in approximately 17 years (Figure 4). Even

reducing dredging depths would not help for very long in the upper bay. Fig- ...

ure 5 shows estimated lifetime of suitable sites based on reduced channel

depths. It was determined that for the upper bay channel to be kept open, the

majority of dredged material would require removal to approved ocean disposal

279
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0.

11-44

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280
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/ / - ,~ ,=.

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" ,.,., ,-l4- f ETIMATED MINAUO

CALCMAT60 LIPUTSS (Y...b

Scale ITO 270

Figure 4. Capacity of and remaining years for all

currently approved upland disposal sites

at Coos Bay

sites. These predictions were verified in 1980 by the Coos Bay Estuary Management Plan (1) which reported that material must be disposed of in the ocean

if the upper bay channel is to be kept open.

This scarcity of economically and environmentally acceptable upland and

in-bay sites, and criteria established in Sections 102 and 103 of the Marine

Protection, Research, and Sanctuaries Act of 1972 (MPRSA), required evaluations prior to disposal in the ocean. Portland District initiated special

studies starting in 1979 to assess the feasibility of utilizing ocean disposal of materials from the upper bay. Criteria established in MPRSA required anevaluation of the material and comparison with the area of the ocean to be

used for its disposal because of the high organic levels found in sediments

between river km 19.3 and 24.14 due to the industrial and silvaculture inputs

to these materials.

PLAN OF STUDY

KW Objectives

The Coos Bay studies were planned as a 3-year multiphase effort with five ,.

major objectives:

1. Determine the best possible location(s) for a permanent ocean disposal site(s) to receive marine sand and/or slightly contaminated

fine-grained dredged material.

281
., -o7JI~~~~'.. T T TTZ, I .L9LI.- 

LINUS -:.-.-.

1g.0.-.O 6 711

i " 'o 9.1 li

500 K__ _.. D..,10.7 M

1S LlI|WIT ... ,. Co.d'te

400

3W -

E

200~

4.; _ ____I ___ 100

2.3 TO 9.6 9. T 14.5 14.5 TO 19.3 19.3 TO 24.0

Channel Reach KM rom Mouth

Figure 5. Life expectancy of remaining upland

and in-bay disposal sites at reduced

dredging depths .%

2. Determine the suitability of ocean disposal of these materials, as .. ' '

required by MPRSA and ensuing regulations (40 CFR 220-225, 227-229).

3. Determine the fate of dredged material deposited in the established

disposal site.

4. Establish regional testing procedures and verify existing testing and

modeling procedures required by MPRSA.

5. Utilize the long-term comprehensive studies at Coos Bay for possible

determination of probable impacts at other Portland District ocean

disposal sites.

These five objectives will be discussed in the following paragraphs.

Objective 1. The interim ocean disposal sites for Coos Bay, designated

by the U.S. Environmental Protection Agency in the 1977 Combined Federal Regulations (40 CFR 220-229), were selected utilizing the best engineering judgment and economic information available at the time of selection. Limited

environmental information was available. The study plan called for the offshore area, including the existing disposal sites, surrounding the entrance

channel to be evaluated for biological, chemical, and hydraulic characteristics, as required in 40 CFR, parts 228.5 and 228.6. These studies would be

used to select the best possible location for an ocean dredged material disposal site. %

282 -

.-.... , ,.. ...... -.-. .,....,.,............. ,.,..... ,..... .,...... ...- ,.,... . .... . ... ,..-......,. ..-..-. , ,
., - .-

Objective 2. The site or sites located in objective 1 may or may not be

suitable for all types of dredged material located in Coos Bay. Objective 2

was to determine the chemical characteristics of channel sediments in Coos Bay

and the consequences of at-sea disposal by performing bioassay and bioaccumulation tests.

Objective 3. Dredged material disposed of in the ocean off of Oregon is

subjected to extremely high current and wave regimes, and will erode from the

deposition area. Objective 3 was established to determine the rate and direction the dredged material would move after deposition. Knowing this, the 5.

materials can be placed so that they ultimately are deposited on sediments --.-

with similar chemical characteristics.

Objective 4. Both chemical and biological testing requirements of MPRSA

and its subsequent legislation required verification and modifications for the

Pacific Northwest coast of the United States. Objective 4 was established to

adapt the suggested tests for suitability of materials for ocean disposal to

Portland District's environmental conditions and regulatory climate.

Objective 5. The fifth objective was established in the hope that additional long-term evaluations and tests could be avoided at other Portland Dis- tz::!,

trict sites by utilizing the results of the Coos Bay work to reduce the

length, costs, and number of tests.

Phases of Study

The five objectives were planned to be accomplished over a five-phase

plan of study shown below:

Phase I: Plan formulation and pilot surveys

Phase II: Baseline study

Phase III: Disposal operations monitoring

Phase IV: Postdisposal monitoring

Phase V: Analysis and report preparation

The study plan was designed so that each of the first three phases could

result in a usable report should the study be cancelled. Figure 6 indicates

the 3-year, five-phase plan of study. This plan was interrupted by an 8-month

loss of funds, which caused a 2-year slip in the plan due to the seasonality

of field sampling requirements. This figure also reflects the scheduling of a --

steering committee made up of interested Federal and State agencies. The committee was established to review the progress of the scientific work and make

recommendations as necessary.

Contractural Arrangements

The five-phase, multiobjective study plan was presented to interested

universities and research groups, with requests for proposals. Oregon State

* University's (OSU) Civil Engineering Department submitted the successful pro-

* posal and was awarded the 3-year, multiphase contract.

283

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PURPOSE, SCOPE, AND RESULTS

Phase I

Purpose and Scope

Phase I studies were designed to examine the physical, chemical, and bio- .*e

logical characteristics of channel sediments and the general offshore area

near the entrance to Coos Bay. The studies were designed to provide data to

select candidate ocean disposal sites for detailed examination during subsequent phases of the project. The objectives of Phase I were to:

1. Define the spatial distribution of benthic and demersal floral and

faunal assemblages of nearshore Coos Bay area.

2. Define the spatial distribution of sediments in the study area with

respect to grain size and volatile solids (organic content).

3. Define the general hydraulic regime of the study area.

4. Define the bathymetry of the study area.

5. Define the physical and chemical makeup of channel sediments that

will be dredged for offshore disposal.

In keeping with the desired management strategy, these objectives would

minimize the differences between characteristics of channel sediments and the

disposal site, avoid impacts on unique biological communities, and minimize

the probability of onshore transport of deposited dredged material. Figures 7a and 7b present the sample locations for all offshore and channel sediment stations. Sediment samples were analyzed for sediment texture, organic

levels, cohesive properties, bulk chemical and elutriate analyses for heavy

metals, chlorinated organic compounds, and other contaminants of concern.

Offshore currents were sampled seasonally with acoustic-recording current

meters to determine vector average currents and instantaneous local

velocities.

Benthic faunal assemblages were determined by using a stratified random

sampling program with a one-tenth square-meter box corer (6). Species composition, relative abundance, and density of organisms were determined in the

study area. Figure 8 shows locations of all benthic stations occupied during

phase 1. Otter trawls for demersal fauna were carried out at 20-m depth intervals and analyzed for species composition and catch per unit effort.

Results

Study results from Phase I, reported in Coos Bay Offshore Disposal Site

Investigation Interim Report, Phase I (2), demonstrated the offshore Coos Bay

area is hydraulically very active. Mean currents and wave induced seafloor

velocities frequently occur in the range of 30 to 60 cm/sec throughout the

year. Average currents tend to follow the bottom contours and are southerly

from April through November, reversing to northerly during the winter months.

These directional trends are consistent with those previously observed for the

Davidson and California currents. Sediments are clean and coarse nearshore

285

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"" (0.5 percent volatile solids, 0.25 mm median diameter) and become more organic

~~~and finer with increasing depths offshore (3 percent volatile solids, 0.08 mm .-.-v

median diameter at 90 in). The chemical characteristics of the sediment in- . ,-

cluding total solids, talorganics, ioadilndgreaseweefudt

.- increase with decreasing grain size offshore (2). The nearshore benthic in-

*faunal community in the depth range of 10 to 45 m was found to be composed of -'..''.

many species typical of a high energy sandy bottom. The offshore region be- -..-

' ~yond 45 m exhibited even greater species richness and diversity than the' .-.,

-' inshore area. The shallowest areas offshore tended to have faunal and sedi-. ", ..-

= ment affinities with the nearshore study area, while the deeper regions tended

to be more typical of a marine soft-bottom community.

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Figure 9. Distribution of sediments by median grain

size and percent volatile solids

minimize differences between dredged material from Isthmus Slough and in situ

material offshore. and to minimize onshore transport of resuspended materials,

the physical-chemical studies indicated the 90-mn contour was preferred for

* dredged material disposal. Biological study results identified a region between 45 m and 65 m where lower abundances appeared in both infauna and epifauna, even though diversity values remained quite high. This appeared to be

an area of seasonal transition in both faunal and sediment characteristics.

It was reasoned that biological tolerance to varied sediment conditions may be

quite high in this region of great temporal change. Consequently, both the *

90-rn and 60-n contours were established as candidate disposal sites G and H

*(Figure 10). In addition to these two sites, the north interim disposal area,L

site F in Figure 10, was selected by Portland District to be included in

Phase I1, predisposal baseline studies. This was to determine suitability of

this site as a sand dredged material disposal area.

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Figure 10. Locations of candidate disposal sites for

Phase II baseline studies provided three seasonal (summer, spring, and

fall) physical, chemical, and biological data collections at the three candidate disposal sites between May 1980 and May 1981. Bioassay/bioaccumulation

studies evaluated the toxicity of Isthmus Slough sediments to representative

marine organisms (9). The results of these studies aided in the selection of

a test disposal site to monitor during the Phase III dredged material disposal

operations. The test site was selected based upon sediment compatibility,

avoidance of impacts on significant biological communities, and minimization ".

of onshore transport of dredged material.

Physical studies were conducted to examine sediment characteristics at

the three candidate disposal sites and to evaluate materials during and after . ;

disposal operations. Sediment characteristics evaluated in this study included sediment texture and organic levels. Offshore currents were sampled ;. .

seasonally with digital recording acoustic current meters to determine vector

average currents and local instantaneous velocities. Current and sediment

texture data were combined to assess sediment erosion capacity.

The Koh-Chang instantaneous injection disposal model (3) was made opera- % -

tional by OSU for the Pacific Northwest coast conditions. The model was

operated for conditions which approximate disposal of Isthmus Slough sediments

at each of the candidate disposal sites. Estimates of plume concentrations

and material accumulation at the three candidate disposal sites were made.

289

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Chemical studies were conducted to establish sediment chemical characteristics and contamination levels in both the Coos Bay navigation channel and

the proposed offshore disposal areas. The studies included four sampling

times from March 1980 through April 1981. The sampling times were selected to

cover approximately a year's duration to identify possible temporal fluctuations in sediment and water column parameters. Total sediment chemical constituency was determined for core samples obtained at five locations for each

disposal site.

Figure 11 presents sample locations at the candidate disposal sites for

chemical, biological, and sediment texture analyses. Sediment and water

column chemical parameters were selected to provide characterization of both

major components used in classifying the sample and the minor components useful in identifying sample contamination from pollution sources.

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site chemical, biological, and physical studies

Bioassay and bioaccumulation tests were conducted for sediments from the

Isthmus Slough navigation channel. Both solid phase and suspended phase tests

were performed using appropriately sensitive organisms indigenous to the offshore disposal site environment.

290

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Elutriate tests on Isthmus Slough sediments indicated very little release

of toxic contaminants such as heavy metals or chlorinated organic compounds

into the solution phase (2). Thus, only solid and suspended phase toxicity

tests were performed. Specific organism selection for testing was based on

Phase I biological studies. Organisms were selected that could be obtained in

sufficient numbers that represented different feeding types, and that were

thought to be appropriately sensitive to exposure from contaminated sediments. N

Suspended phase tests used two pelecypods (Macoma inclusa and Acila

castrensis), a crustacean (Cancer magister), a sand dollar (Dendraster

excentricus), and a polychaete (Abarenicola pacifica). Solid phase tests used

Macoma inclusa, the crustacean Crangon nigrica; the sand dab Citharicths,

sordidus, the polychaete Abarenicola pacifica, and the amphipod Rhepoxynius

epistomus.

Algal toxicity and bioaccumulation of trace metals and chlorinated hydrocarbons by a polychaete worm were also assessed in separate tests. The algae

bioassay utilized a specific marine phytoplankton organism, Iunialiella

tertiofecta, and was intended to assess the toxicity of soluble phase constituents released by elutriation. To assess compounds from the sediments, a

deposit-feeding organism (Abarenicola pacifica) was selected that was known to % .

bioaccumulate sediment-bound contaminants from previous studies (5).

Biological studies were designed to quantitatively determine the differences in the benthic fauna between the three candidate disposal sites and

within each candidate disposal site, and to assess the seasonal differences

exhibited over 1 year at a single site selected for experimental test disposal

of dredged material.

To determine the infaunal similarities, five permanent stations were

established within each candidate site. Each of the three candidate disposal

sites was then sampled with a box-corer and a 1-m beam trawl during May 1980.

To increase the sampling precision, five replicate box-corer samples were collected from each of the five permanent stations at each site, and two replicate trawls were made at each site. The abundance and distribution of the

infaunal species were statistically compared using multivariate statistical

techniques to determine the between-station differences of benthic infauna at

each site. The three candidate sites were then compared against each other on

the basis of species composition and abundance.

Results

The Phase II and III Coos Bay Offshore Disposal Site Investigation

Interim Report (4) selected site H as the optimum location for dredged material disposal monitoring studies in Phase III.

Site G was shown to minimize the difference between in situ and dredged

materials. However, an emerging scallop fishery was discovered in the vicinity of this site. Site G was eliminated from further consideration to avoid

interference with a commercial fishery.

Site F was proved to be hydraulically quite active. Any material deposited at this site would be eroded very quickly. Prevailing wave and current

directions would likely transport eroded sediments to the estuary mouth and to

291
a - f ~ o . r - r . .- r . I or * v~ ,w . .

adjacent beaches. As a result, site F was eliminated from further consideration to avoid impacting the shoreline and estuarine environment. However, it

was retained for consideration as a disposal site to receive sand dredged

material that would act as beach nourishment and/or a littoral transport site.

The biota at site H continued to exhibit desirable stress tolerance char- r.--

acteristics during the Phase II studies. The sediments at site H are approximately an order of magnitude more coarse and less organic than the dredged

material from Isthmus Slough. This dissimilarity is not desirable in terms of_

sediment compatibility but did facilitate tracing the ultimate fate of the

submerged disposal mound during Phase III. Prevailing currents at site H are

parallel to the shoreline; no significant onshore transport of eroded dredged

material would be anticipated. Also, bioassay and bioaccumulation study results suggest that no adverse impacts on the biota would be anticipated at

site H. Based on biota stress tolerance, dredged material tracing ease, longshore transport direction, and lack of fisheries impact, site H was selected

for Phase IIl disposal operation monitoring studies and the Phase IV postdisposal impacts monitoring studies.

Phases III, IV, V

Purpose and Scope

The Phase III disposal monitoring investigations were field studies designed to evaluate the fate and impact of slightly contaminated sediments

dredged from Isthmus Slough and deposits at offshore disposal site H in 60 m

of water. Two hopper dredges, the YAQUINA and BIDDLE, were used to deposit

approximately 45,111 cu m at site H in August 1981. Water column measurements

were made to quantify currents; disposal plume location, geometry, and density; water quality; and epibenthic biota impacts. Sediments were sampled

before and after dredged material disposal to determine the dimensions of the

disposal mound, to quantify changes in sediment physical and chemical characteristics, and to assess impacts on benthic communities.

Phase IV postdisposal monitoring investigations included a laboratory, * '

analysis of Phase III data, as well as field studies to assess the persistence

of the disposal mound and the related impacts on biological communities.

Plume measurements from Phase III were interpreted to examine the utility of

the Koh-Chang dredged material disposal model. The final report was prepared

as part of the Phase V effort. A funding delay caused a 1-year delay in returning for postdisposal field monitoring and prevented deterznination of short

changes at the candidate site.

Results

Sediment results summarized below are taken from Coos Bay Offshore Disposal Site Investigation Final Report (7).

Disposal site H was sampled I day after completion of disposal operations. The samples displayed characteristics of dredged material. Layering ....

was apparent in many samples. Dredged material was identified as having ",a..

median grain size near 0.05 mm, as opposed to in situ material that is greater

than 0.1 mm, and volatile solid levels above 4 percent; in situ material is

2 percent or less. A dredged material disposal mound was readily identified

292

* . . . . - . . * . - . . . . .. . .

. . . . * . . ... . . . .. .

._ _ ,. . .,_, s ... I . 9 , - ' -' -.. - . . . . ... €.-* *- . - . . . . . . .• . -
and determined to have an area of approximately 0.46 by 0.46 km. After

1 year, some dredged material could be distinguished in five samples; however,

most of the material was found in lenses beneath the surface of native material. It was hypothesized by OSU that winter storms had transported native

materials over the disposal mound, armoring it from further erosion. However,

the funding delay kept this from being verified. After 19 months (and the

* limited amount of dredged material disposed of) the detected mounds were mixed

beyond recognition with native sediments.

~Current Measurements

th d

Current meter studies indicated that both wave-induced seafloor velocities and mean currents were sufficient to erode native marine sands, as well as

the deposited dredged material during a significant fraction of each season. '.i

Prevailing currents in the depth of water at site H would tend to transport

eroding material parallel to the shoreline or offshore, causing the material

to be dispersed without affecting beaches or estuary entrances. Figure 12

depicts fall and winter bottom currents and induced surface currents for current meter stations occupied during 1977 and 1980, and is intended as an

example of average conditions encountered during the current meter studies. '.*

NMER AE 

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Fiur Botto Curree n al otmcret ietos

and wind-induced surface wave direction

293 ,,,- '

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Model Studies

Field studies of the resultant dredged material solids plume were conducted. The primary cloud collapsed on the seafloor before the dredge vacated

the disposal site. As a result, the properties could not be quantified during

descent and collapse with surface-deployed equipment from the research vessel.

However, the secondary cloud of suspended solids was monitored and found to

persist for I hr. The Koh-Chang dredged material dispersion model, modified

and calibrated for instantaneous discharge, proved satisfactory for predicting

both the primary could accumulation on the seafloor and the secondary clouds

if the silt clay size parameter in the models was reduced to a porosity of

96 percent.

Chemical Studies

Water column monitoring of the plume revealed no acute conditions during

disposal operations. Ammonia-nitrogen, copper, and manganese showed elevated

concentrations for a short duration. Sediment samples showed a return to

background conditions after 1-1/2 years of sampling. Chemical dissimilarity

between dredged material and native sediments was evident immediately after

disposal operations. Concentrations, however, were lower than for sediments

aiialyzed from the channel, indicating mixture with native sediments.

Biological Studies

Biological conditions were examined for each of the five stations at the

study site by comparing differences in benthic infauna among stations and

among seasons. Two levels of comparison were made, comparison of major taxonomic groups (annelids, molluscs, arthropods, echinoderms, and miscellaneous)

and comparison of selected individual species.

Abundance and densities of benthic infauna within the major taxonomic

groups varied widely. Variations in major taxonomic groups were viewed over

time. Polychaete annelids and echinoderms showed significant variation among

the five stations at the disposal site during all sampling periods. Crustaceans showed significant variation only between the period May 1981 and February 1983. Molluscs varied significantly during all periods.

When the major taxonomic groups were examined as to variation between

stations, polychaetes showed significant variation, while molluscs varied significantly during some seasons and not others. The crustaceans were usually

very consistent. Even with large variations observed between stations, each

site appeared to have sone s;poois whose pattern of variation would be suitable for detecting changes.

Polychaetes were the most abundant group at the disposal site. Abundances exceeded 1200 per square meter both prior to and after disposal. Polychaete abundances continuously increased throughout the study with a maximum

abundance exceeding 3300 sq m in February 1983. Crustaceans and molluscs were

nearly equal in abundance during most sampling periods, with abundance levels

only slightly reduced after disposal.

Principal component analysis and MANOVA programs were used to evaluate

the polychaete, crustacean, and mollusc species data between stations and

294 "Z.
between seasons. The species data showed two groups, those with little or no

difference between the stations (i.e. depth, sediment, or volatile solids),

and those showing differences.

Species within the major taxonomic groups exhibited three types of dis- ,

tributional patterns: species with peak abundances at the shallower water

stations (60-m contour); those with peak abundances occurring at the deeper

water stations (80-rm contour), many of these species having intermediate abundance levels at the intermediate depth (70-m contour); and a third group of

species that seemed to be rather evenly distributed across the five stations.

Using the same statistical procedures, the variability of each individual

station over the period May 1980 to May 1981 was analyzed to determine if

there were seasonal differences at each station. While some species varied .

significantly at an individual station, they did not vary widely at all stations. The individual species populations fluctuated throughout the study, N

with little consistent pattern and few species if any taxonomic group exhibited significant postdisposal changes. Several explanations for this are dis- .

cussed later, but the large natural variations observed in the nearshore

coastal zone off Oregon clearly demonstrated the need for evaluation at the

species level, if naturally occurring perLurbations are to be distinguished

from man-induced changes.

The relationship between volatile solids and the abundance of major taxonomic groups was plotted for the faunal data for each of the five stations at

the disposal site. Polychaete and mollusc abundances showed a positive correlation with increased volatile solids, with the highest abundance occurring

between 2 and 4 percent. Crustacean abundance levels appeared relatively constant and showed no correlation with volatile solids. Temporal patterns displayed by the fauna at the site appeared to be characteristic of the fauna in

a moderate to high energy environment. The data set identified the differences which occurred both between stations and sampling periods. The large

variations observed in data at site H suggested that these organisms had a

past evolutionary history of frequent disturbance, and were well adapted to

environmental disturbance levels of the magnitude encountered in dredged material disposal.

Impacts from the test disposal operations were probably reduced, however,

because of the small quantity of material (45,111 cu m) disposed of and the

fact that the material was not deposited directly over established benthic

stations.

CONCLUSIONS

The multiple-year evaluation study conducted by Oregon State University

consisting of general survey, baseline, disposal monitoring, and postdisposal

monitoring studies concluded that the general area around the 64-m contour was ,.,.

a transitional region for both the benthic community and the sediments. While

this area had sediments coarser and less organic than Isthmus Slough sediments, it was the closest approximation to the dredged sediments in the entire

economically feasible study area. It was reasoned that this area could

tolerate the stresses of exposure to dissimilar sediments, as the biota

295
exhibited characteristics between those of the dynamic nearshore and static .

offshore environments. Current and wave studies from this area also assured

researchers that no onshore transport of clay/silt-sized material would occur.

The above conclusions, plus the fact that no effects on the biota were "

shown by the bioassay and bioaccumulation studies, resulted in OSU suggesting

the general area around the 64-m contour as the most likely region to establish an ocean dredged material disposal site for fine-grained materials.

SITE DESIGNATION

Site Evaluation

Portland District accepted OSU's report in June 1984. The studies had

fulfilled all originally outlined objectives and had collected all information

required in 40 CFR, 228.5 and 228.6. These regulations promulgate requirements of the Marine Protection, Research, and Sanctuaries Act, which requires

basic environmental information to be obtained before designating a site.

OSU's two interim reports and their final report were utilized by Portland

District as the site evaluation studies required in the above cited CFR.

Site Designation

The evaluation studies were used to prepare a combination document formatted as an Environmental Impact Statement, which complied with the National

Environmental Policy Act (NEPA), and also responded to the five general and

eleven specific criteria for site designation in 40 CrR 218.5 and 229.6,

respectively. The draft document (11) considered all areas studied by OSU as "-

alternative sitings for a disposal site, a deeper continental slope site re.- .;,.,

quired in MPRSA, and no action required by NEPA.

The environmental impact statement considered three basic types of sediments to be disposed of in the ocean from the Coos Bay navigation channel:

Type 1. Predominantly clean sand of marine origin typical of sediments

from below Coos Bay river km 19.3.

Type 2. Finer grained sand and silt containing some volatile solids

typical of sediments from between Coos Bay river km 19.3 and 22.5.

Type 3. Highly organic fine material (6 to 20 percent volatile solids)

typical of sediments from above Coos Bay river km 22.5.

Various disposal sites and combinations of these materials were proposed

and a best alternative suggested. bi'

The area studied by OSU as site H, centered on the 55-m contour, was "

shown after completion of the studies to be in the vicinity of a recently

exhausted commercial scallop bed. The western edge of the site encroaches

into the southern boundary of the bed. This site was adjusted to the 46-m

contour which preserved the physical attributes on site H, but caused the

biota to become more similar to the inshore sites.

296

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Portland District proposed, as the preferred alternative, a combination

of the two existing inshore sites (E and F), and adjusted site H (Figure 13).

The adjusted site H could receive type 2 and 3 materials, up to 382,300 cu m

per year, and sites E and F would receive 688,140 cu m per year of type 1

sediments. The placement of type 2 and 3 materials at adjusted site H would

keep fine-grained material in the long shore current regime and off of beaches

and estuaries. Placement of sand size and larger textured material at sites E

- and F would ensure that this material was available in the littoral transport

system. Upon approval of the Environmental Impact Statement, these sites will

be designated by the U.S. Environmental Protection Agency as final ocean

dredged material disposal sites, available to receive approved materials .-

tested under 40 CFR 227. '

SITI

0OT1

Figure 13. Proposed ocean dredged material

disposal site locations

Site Management

A management plan is in the process of being prepared. The plan will

include detailed descriptions of locations of types and volumes of materials

to be placed at both remaining upland sites and at the ocean disposal sites,

times of the year that various options should be used for disposal of materials, and what types of materials should be placed at each site. Alternative

methods of dredging the materials and economics of each method will be examined

and coupled with the appropriate disposal option. An important part of the

plan will be a monitoring program established for the ocean disposal sites.

The program would be designed to ensure that no dredged material is transported to, nor affects known ocean resources. The plan would be prepared

297

...-. -

.. *... 

.N.%
-L L- L 7 V1 X V

utilizing the evaluation studies. It is foresec- that this management scheme

will ensure that dredged materials are placed in the most environmentally

compatible and economically feasible disposal areas.

SUMMARY

The evaluation studies conducted for Coos Bay ocean dredged material disposal sites have ensured full compliance with all existing International,

Federal, and State environmental regulations. More importantly, the long-term

nature of studies and the full range of tests conducted and modified for the

Pacific Northwest Coast conditions have allowed for shorter term and less expensive tests to be conducted at the remaining Portland District ocean disposal sites. Evaluation studies are under way for eight remaining Portland

District ocean disposal sites with comparisons made with the Coos Bay data.

This has allowed for the eight remaining sites to be evaluated for less cost -'

and time than the cost for the Coos Bay studies alone.

These studies are using a new evaluation technique developed jointly by

* the Corps of Engineers and EPA (10) which requires using existing information -...-

to the extent possible. New data are only gathered when they are specifically

missing from the literature for the area being considered for site designation. Even when data gaps are encountered, utilizing the Coos Bay data base

allows for much shorter and less intense sampling efforts to obtain the missing data. This is done by determining that the smaller field sampling effort

is similar to the longer term data base and by inference showing whether they

behave similarly or differently. If a difference is inferred, additional

field studies could be required prior to designation.

REFERENCES

. 1. Coos County. 1982. "Coos County Comprehensive Plan," Coos County Board

of Commissioners, Coquille, Oreg.

- 2. Hancock, D. R., Nelson, P. 0., Sollitt, C. K., and Williamson, K. J.

1981. "Coos Bay Offshore Disposal Site Investigation Interim Report

Phase I, February 1979-March 1980," Report submitted to U.S. Army Corps of

Engineers, Portland District, Contract No. DACW57-79-C-0040, Oregon State

University, Corvallis, Oreg.

3. Koh, R. C. Y., and Chang, Y. C. 1973 (Dec). "Mathematical Model for h

Barged Ocean Disposal of Wastes," Environmental Protection Technology

Series, EPA 660/2-73-029, Washington, D.C.

4. Nelson, P. 0., Sollitt, C. K., Williamson, K. J., and Hancock, D. R.

1983. "Coos Bay Offshore Disposal Site Investigation Interim Report Phase . .

II, III, April 1980-June 1981," Report submitted to the U.S. Army Corps of

Engineers, Portland District, Contract No. DACW57-79-C-0040, Oregon State

University, Corvallis, Oreg.

. 5. Oakley, S. M., Williamson, K. J., and Nelson, P. 0. 1980. "The Geochemical Partitioning and Bioavailability of Trace Metals in Marine Sediments,"

Water Resources Research Institute, Oregon State University, Corvallis,

Oreg.

298

'.2.j~2 -~ .~*, ... *. * -*-----c~& : ".. .- "-*. "'.'.. . .* ". ; . .' - .... .- ",. . .",' •". .'- "-
6. Peguegnat, W. E., Peguegnat, L. H., James, B. M., Kennedy, E. A., Fay,

R. R., and Fredericks, A. D. 1981 (Jan). "Procedural Guide for Designation Surveys of Ocean Dredged Material Disposal Sites," Technical Report

EL-81-1, U.S. Army Engineer Waterways Experiment Station, Vicksburg,

Miss.

7. Sollitt, C. K., Hancock, D. R., and Nelson, P. 0. 1984. "Coos Bay Offshore Disposal Site Investigation, Final Report, Phases IV, V, July 1981-

September 1983," U.S. Army Corps of Engineers, Portland District, Contract No. DACW57-79-C-0040, Oregon State University, Corvallis, Oreg. - .

8. U.S. Army Engineer District, Portland. 1976 (Aug). "Final Environmental

Impact Statement; Operation and Maintenance Dredging Coos Bay and Coos

and Millicoma Rivers Navigational Project, Oregon," Portland, Oreg.

9. U.S. Environmental Protection Agency/Corps of Engineers Technical Committee on Criteria for Dredged and Fill Material. 1978. "Ecological

Evaluation of Proposed Discharge of Dredged Material into Ocean Waters;

Implementation Manual for Section 103 of Public Law 92-532 (Marine Protection, Research, and Sanctuaries Act of 1972)," July 1977 (Second

Printing, April 1978), Environmental Effects Laboratory, U.S. Army Engineer Waterways Experiment Station, Vicksburg, Miss.

. 10. U.S. Army Corps of Engineers/U.S. Environmental Protection Agency. 1983.

"Draft Technical Guidance for the Designation of Ocean Dredged Material

Disposal Sites," U.S. Army Engineer Waterways Experiment Station,

Vicksburg, Miss.

I1. U.S. Environmental Protection Agency/U.S. Army Corps of Engineers. 1984.

"Draft Environmental Impact Statement, Coos Bay, Oregon, Dredged Material

Disposal Site Designation," U.S. Environmental Protection Agency, Criteria and Standards Division, Washington, D.C.

299

• . .

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

. .... .
WASTEWATER TREATMENT BY SOIL

T. Tanimoto

Director, Seacoast Division .

River Bureau, Ministry of Construction

INTRODUCTION

Japan has enjoyed a remarkably rapid economic growth since 1950. Population concentration in the urban areas, economic growth, and industrial development have increased the amount of pollution all over the country, especially

in the urban areas. There was no pollution problem so long as the pollution

load remained far smaller than the environmentally permissible limit. However, water quality in public water bodies such as rivers and lakes deteriorated rapidly once the pollution load exceeded the permissible limit and this

polluted water resulted in nutrient-rich sediments gathering at the bottom of

lentic water bodies, such as lakes and marshes. It is very costly to remove

these nutrient-rich sediments caused by the polluted water; therefore, it is

cost-effective to purify polluted water before it reaches natural water

bodies. It is especially important to remove nitrogen and phosphorus. To

treat pollution load at low cost, the methods are: first, not to dissolve;

second, if it is dissolved, keep dilution as low as possible; and third, treat

the pollution at its source.

Though the activated sludge method is the most popular method in the

world, there is a wastewater treatment technology newly developed in Japan

that will be introduced in this paper. This is the most economical and energy ,

saving method since it makes best use of natural characteristics, and treatment within individual households is possible if there is a small piece of

land.

SELF-PURIFICATION AND SEDIMENT SUBSTANCES IN RIVERS

I.

Natural self-purification will not be entirely expected once the pollution load exceeds the environmentally permissible limit. This theory will be

applied to the water and air pollution. In the case of rivers, though selfpurification is expected even in deteriorated rivers, it will hardly function

if the river bottom is included.

Organic substances discharged into the water are transformed into simple

inorganic substances in the form of H2 0, CO2, NO3 SO4 , PO4 etc., through the

oxidation function of various aerobic bacteria. The dissolved oxygen in the

water will be decreased in volume due to oxidation. The more the water is

polluted, the more oxygen is consumed; fish therefore cannot live in heavily

polluted water. Some of the dissolved substances will be released to the air,

some will be dissolved in the water, and others together with undissolved substances will settle to the bottom. As organic substances decompose, plants

such as duckweed will take up CO2, N, and P as nutrients. These nutrients

will be released upon anaerobic decomposition. In this step, foul odor gas

including hydrogen such as CH4 , NH3 , and H2S will be produced. This cycle

300 ,..-

-'''.'. 2-'_._.L, : '" * ' . . '-'............."""""..... __" "..... .... "" 
will repeat until the sediments at the bottom of the river are moved downstream into the stagnated water body.

The nutrient sediments accumulated in the stagnated lakes and seas which

have rivers in their catchments consist of these substances. Substances which

normally undergo self-purification in rivers are causing many problems in

stagnated water bodies due to overloading. It is far more economical and

environmentally acceptable to treat the wastewater at the source rather than

to treat the sediments.

WATER POLLUTION IN THE STAGNATED WATER BODY IN JAPAN

Lake Biwa, Lake Kasumigaura, Lake Suwa, and Seto Inland Sea (Figure 1) - are representative of stagnated water bodies in which eutrophication is distinctly observed. For the lakes, the population in the drainage basin, chemical oxygen demand (COD) concentration, sewerage served population ratio, and

number of piggeries are shown in Table 1. Table 2 shows the COD, total nitro- z k

gen (T-N), and total phosphorus (T-P) for the Seto Inland Sea. The frequency

of red tide is illustrated in Figure 2. Pig raising is very prosperous around .*.

Lake Kasumigaura, and the COD concentration shows the highest rate in 1979 due

to the increase in the pig raising since 1977. Water quality in Lake Biwa and -,

Lake Suwa is gradually being improved after the worst situation in 1973. The

water quality of the Seto Inland Sea is also being improved since 1974 and the

frequency of red tide has improved since 1977.

Water pollution has improved as a result of the enactment of numerous

laws on water pollution prevention in 1970. Through these laws, the central

government, prefectural governments, and the people endeavored to mitigate the

pollution load.

WATER POLLUTION PREVENTION ADMINISTRATION IN JAPAN

Basic Measures

The administration of water pollution prevention in Japan is being comprehensively carried out by the following four measures.

a. Setting up environment standards showing the target of various

measures.

b. Effluent regulation according to effluent standards to achieve a.

c. Carrying out public works such as sewerage, dredging, and water

conveyance for purification.

d. Public cooperation such as self-control of usage of detergent contaning phosphorus compounds.

Effluent Control

In order to prevent water pollution, the Water Pollution Prevention Act

was enacted in 1971. The objective of this act is to "prevent the water

pollution in the public water bodies, hereby, to protect people's health and

preserve the living environment through controlling the effluents which are

301 -U--.-

. ".. .",'o
N Hokkaido

LakeBiwaLake Kasumigaura

Seto Inland Sea

Kyushu

Figure 1. Location of representative stagnated

water bodies *

%U.

302
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303 ?

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TABLE 2. TRANSITION OF SEAWATER POLLUTION

IN SETO INLAND SEA

Yea C)D ransparancy T-N T-P

(ppm) (m) (ppm) (ppm)

1982 1.8 5.0 - -

1983 1.7 6.2 0.275 0.023

1984 2.1 6.5 0.292 0.035

1985 1.6 6.6 0.300 0.028

1986 1.6 6.9 0.398 0.030

1987 1.7 5.8 0.277 0.029 i1988 1.5 6.6 0.243 0.023

1989 1.3 6.4 0.257 0.026

1990 1.5 5.7 0.265 0.026 " .

1991 1.6 6.5 0.246 0.024

40

STotal

Damaged 298 300 326 .

300. -.-. '%

210 236 216 218

20 199 201

z164 165

136

100. 79 61 67 !"" "

F r Ln Year

~ ~ ~ , ~ ~ ~ r C o Co (0...-...

ON 0 0 O N is 0 O 0% Cs O p

-4 - -4 - 4 1- .-4 -4

Figure 2. Frequency of red tide into Seto Inland Sea

304

b'~. 4 .-. : .

...4 '7-~
discharged from factories and buildings." This act contains no clause to control effluent containing phosphorus compounds at present, but such a clause

will soon be added by Cabinet Order.

The Special Measures Act on Environment Preservation for the Seto Inland

Sea was enacted in 1973. The objective of this act is to "take special measures on control of setting up special facilities, prevention of damage occurrence due to the eutrophication, preservation of natural seacoast, etc., as

well as to decide the necessary matters on planning preparation in environment

preservation of the Seto Inland Sea in order to execute the effective measures

for the preservation of the environment of the Seto Inland Sea." This act

contains a clause giving official guidelines to control the effluents and substances containing phosphorus compounds.

On the prefectural level, Shiga and Ibaragi prefectural governments which

govern the drainage of Lakes Biwa and Kasumigaura, respectively, prepared

their own ordinances to mitigate eutrophication. It is widely recognized that

the regulations through these ordinances were very effective.

In July 1984, the Special Measures Act on Water Quality preservation in

Lakes and Marshes was enacted in order to take measures more comprehensively

and drastically. The objective of this act is to "prepare for the planning on

measures to be carried out to preserve the water quality in the lakes and

marshes of which the environment standards of water pollution are urgently

attained, and to take special measures to control the facilities which discharge effluents or substances which may cause the water pollution in large

scale as well as to carry out the public works for the purification of water

and also to stimulate the people's cooperation." This act is a recent result

of the comprehensive water environment policy.

ADVANTAGES AND DISADVANTAGES OF VARIOUS WASTEWATER TREATMENT

The methods for wastewater treatment which have been used historically

are:

a. Underground infiltration through pits.

b. Oxidation ponds.

c. Biofilms.

d. Trickling filters.

e. Activated sludge.

The advantages and disadvantages of these methods are discussed below. The

removal ratio of BOD load and suspended solid (SS) mentioned below apply to &-"

wastewater from households, i.e. the BOD concentration is about 200 ppm.

Underground Infiltration Through Pits

Since clogging by the SS on the soil surface at the bottom of the pit is

inevitable, only a small volume of wastewater should be allowed. The method

can purify wastewater well with regard to its BOD, nitrogen, and phosphorus,

305

* ,"- '2
and the cost is zero, but this method has the fatal disadvantages of foul odor

and sanitation problems.

Oxidation Ponds

This method removes SS and reduces BOD concentration to some extent and ..

is easy to maintain. The problems with this method are that nitrogen and

phosphorus are removed only marginally and that a large land area is required. ' .1-

Biofilms

This method purifies wastewater by using aerobic bacteria which exist at

the surface of gravel, etc., through repeating contact, release, and exposure

to the air. This system can treat about 1 cu m of wastewater per day per

1 cu m of contact material, and can remove 80 to 90 percent of SS and 65 to

85 percent of BOD load. The defects are that the contact material will be

clogged and that the treatment volume is not great in comparison with the

Trickling Filters

"-..'',

This method was developed for the purpose of mass treatment. The improvement is made using biofilm and sprinkling wastewater intermittently over

the contact bed. This can treat about 2 cu m of wastewater per day per square

meter, and can remove 75 to 90 percent of BOD load. The advantages are:

a. Flexible to the fluctuation of waste load.

b. Easy operation.

c. Less sludge production compared with activated sludge method.

d. Valid in nitrification.

The disadvantages are the occurrence of foul odor and contact flies, and that

a large amount of land is required compared with the activated sludge method.

Activated Sludge

This method was also developed for mass treatment and can treat 10 to

20 cu m per day per square meter. The principle is to use the aerobic bacteria by blowing air into the wastewater and stirring. This system can remove

about 90 percent of the BOD load, but is not so available with regard to the

removal of nitrogen and phosphorus.

The advantages are that it is suitable for mass treatment, has less of a

foul odor, no occurrence of flies, and a low cost compared with trickling filters. The disadvantages are that it is not appropriate for load fluctuations,

produces a large amount of sludge, has less removal of nitrogen and phosphorus, has less nitrification, and has high maintenance cost.

306

...........- - . °........................................................°.=.,....,...... ° .o..... .... .. . .... .,-. .

'-. ". "'' , ' " - . """ """ , """" ' " . •""""" """" . .""" ° '." -. .".. " -.- " " -'. -"' -. -" . - -" .. " -" -"
PURIFICATION METHOD BY SOIL

It has been recognized that soil can purify wastewater to a great extent.

Fairly long ago in Japan, the river water quality near rural comiunities was

very good, even though the wastewater from the households infiltrated to the

soil through pits. However, the river water quality rapidly deteriorated once .

the wastewater was piped directly to the river because soil purification was

unable to solve the problems of clogging, sanitation, and foul odor.

Soil has many characteristics. These are as follows:

a. The number of bacteria in the soil is thousands of times the amount

in water.

b. There are many aerobic bacteria in the surface layer and these bacteria can transform NH 4 -N into NO3-N by oxidation.

c. Anaerobic bacteria are in the deeper layers and these bacteria can

transform NO3-N into N2 gas.

d. Soil itself has an almost infinite phosphorus absorption capacity.

e. There is no clogging if the underground is used because soil has

capillary action.

f. Soil has a strong removal capacity of foul odor.

f There are many microorganisms such as earthworms.

The newly developed wastewater purification method using soil simultane- -

ously solved the problems of clogging, sanitation, and foul odor, which were "v

not solved in the past by the pit method, though treating the wastewater beneath the ground succeeded as well in the removal of nitrogen and phosphorus

which are very difficult by other means. The cross-sectional profile of the

concept is illustrated in Figure 3, and the treatment system consists of four

steps, settling tank, circulating contact aeration tank, final sedimentation

tank through biofilm, and trench. The settling tank is expected to remove

about 30 percent of the BOD load through stagnating wastewater for more than

16 hr. The circulating contact aeration tank is expected to remove about

30 percent of the BOD load of inflow water and is designed to cope with 0.3 kg

of the BOD load per cubic meter. This method is intermediate between biofilm

and activated sludge. The final sedimentation tank through biofilm is set up

primarily to remove SS and improve the water quality in order to prevent

clogging in the trench, which is the final step. The final trench is primarily to remove N, P, and BOD load. This facility can display a remarkably high

capacity of phosphorus removal and may be said to be a super high-class treatment system. The final trench is omitted if the land is limited. In this

case since the removal of phosphorus will be degraded and BOD concentration

will be 40 to 50 ppm, it is recommended that an additional (second) circulating contact aeration tank be provided following the circulating contact

aeration tank. The second circulating contact aeration tank would be designed

to cope with 0.2 kg and 0.1 kg of BOD load per one cubic meter if the target

of BOD concentration were 20 ppm and 10 ppm, respectively.

307
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*308
The most specific characteristics of this system are that the surface of

all facilities is covered by ventilative soil; therefore, a very small amount

of sludge will be produced due to the activities of microorganisms such as

earthworms. The problems of clogging, sanitation, and foul odor are simultaneously solved, and N and P which are very difficult to remove by any other

means are easily removed. The construction cost of this system is far more

economical compared with public sewerage system when constructed in the garden

of individual households; the standard cost per capita is approximate US$500,

but pipeline cost will be additionally required when the wastewater is treated 1".

by community.

RESEARCHES IN JAPAN

There are more than 2,000 soil wastewater treatment facilities in Japan,

most constructed in schools and hotels where the waste load fluctuation is

large, and sewerage systems in the rural community where there is sufficient

land space. This system was also adopted for the public sewerage system in .

Shizuoka Prefecture in 1983. In 1978, the Ministry of Construction (MOC)

initiated experiments to purify wastewater from pig raising by soil in Iwate

Prefecture, Tohoku District, from the aspect of eutrophication prevention,

especially in dams. The Environment and Health Center, Okayama Prefecture,

started the experiment on soil wastewater treatment in 1982. Both experiments

will be briefly described.

Experiment by MOC

Iwate Prefecture is located 500 km north of Tokyo. The average tempera- .

ture is 22.8*C in summer and -2.5'C in winter. The treatment facilities were

designed to purify the wastewater from piggeries having 100 pigs, after the

solids and liquids are separated and the liquid is aerated. The treatment

system is the same as mentioned in the preceding section and is shown in Figure 4. The expected wastewater volume was 3 cu i/day. Cultivated soil near

the test site was mixed with pearlite in order to obtain the ventilative soil.

The physical characteristics of the soil are shown in Table 3. Four trenches

25 m long were prepared; three of the trenches were in constant use and the

fourth was prepared for emergency use such as clogging. However, no clogging

in the trench was observed. The trenches were 50 cm wide, but the design

width to purify wastewater for each trench was 1.5 m. One square meter of

trench was therefore charged with purifying 26.7 1 of wastewater per day. The

operation began in January 1978 and the accumulated sludge was extracted three

times:

a. January 1980 from settling tank and final sedimentation tank.

b. October 1982 from circulating contact aeration tank and sedimentation

tank.

c. February 1984 from settling tank and final sedimentation tank.

The volume extracted in 1984 was 8 cu m and this volume was returned to

the activated sludge tank for preliminary treatment.

The wastewater was sampled and the water quality analyzed monthly. Four

years of data (April 1978 to March 1982) were used for this analysis because

309

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@31
other data were not available for the frequency and items analyzed. Fluctua- .. ., f-" "V tions in the data exist to some extent, but these may have been caused by

fluctuations in the number of pigs and by the water sampling method used. The

transition of water quality in each step of the process was obtained from

mathematical means for 4 years and is shown in Figure 5 and Table 4. Seasonal

fluctuations are shown in Figure 6.

Results can be summarized briefly as follows:

a. T-N and NH -N in the settling tank are higher than those of waste- 4

water. This may be caused by the method of water sampling.

b. Seventy percent of the T-N is removed--half of it is removed in the

circulating contact aeration tank and the other half in the trench.

c. Nitrification is observed in the circulating contact aeration tank

and the trench.

d. Phosphorus is almost totally removed in the trench.

e. Ninety-eight percent of the BOD load is removed; most of it is removed in the circulating contact aeration tank and the trench.

f. Only the settling tank and the trench remove SS.

In seasonal fluctuation, T-N and NH -N show a high rate in winter and 4

summer, but no large fluctuation is observed after the trench step.

h. The removal ratio of phosphorus decreases in August and September.

Experiment by Okayama

The experiment facilities were constructed inside the Environment and

Health Center to purify all wastewater from the office. The treatment system

consisted of a settling tank, circulating contact aeration tank, final sedimentation tank through biofilm, and trench, the same as MOC. The trench was

40 cm wide and 4 m long in order to treat 1 cu m of wastewater per day. The

operation began in April 1982. The resulting treated volume was far below the

initial design and was 41.4 i/day/sq m (averaged over a year) assuming that a

2.5-m-wide trench is valid to purify wastewater. Common weathered granite was

used. The data were analyzed once a month (Table 5) in the form of mathematical means.

The wastewater per square meter of land is bigger than the one of MOC,

but 99.5 percent of BOD load, 48 percent T-N, and 95 percent of T-P were removed. Compared with the result of MOC, though the removal ratio of BOD is W)

better, that of T-N is worse. The difference might have been caused by the

soil used. The reason nitrogen was not removed might be because the anaerobic

bacteria were not as active due to the lack of carbon as nutrients for anaerobic bacteria because the BOD load was improved very well. Generally, coliforms will almost always be killed by various kinds of bacteria and protozoan

when they infiltrate the soil I m and by sieving function through soil porosity. In this experiment coliforms were rarely observed after the trench step.

312
0 w

414

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313

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TABLE 4. WATER QUALITY BY STEP (MOC)

Removal

Ratio

Item No. 1 No. 2 No. 3 No. 4 No. 5 x

pH 7.7 7.6 7.2 7.3 6.2 --

BOD, ppm 169 139 81.1 83.8 2.83 98.3

" COD, ppm 112 89.0 62.2 66.1 3.58 96.8

SS, ppm 171 110 100 102 8.7 94.9

NH4-N, ppm 73.0 79.8 35.7 29.5 3.13 95.7

NO2 -N, ppm 1.90 2.28 4.56 5.70 1.20 --

NO3 -N, ppm 4.42 4.42 17.7 22.11 23.79 --

* T-N, ppm 95.4 102.5 66.0 66.7 28.25 70.4

T-P, ppm 23.8 22.90 22.42 19.25 0.58 95.9

Remarks: No. I = Wastewater.

No. 2 = At the end of settling tank.

No. 3 = At the end of circulating contact aeration tank.

No. 4 = At the end of final sedimentation tank through biofilm.

No. 5 = At the end of trench.

314

. . . •... 
-WW - %. Uk Y- - YJ

-W7* -. Y. '%A

300

T-N

No. .2

ppm No

100 No.S" 3 %7

No. 5

200 - NH1.-N L

~.No. 2 N03-N

9.o 30

No TemZ3 ur

No..

PHH

6 c

NO.2

7 10

No.4 P

6' - *

Figure 6. Seasonal water quality

315
TABLE 5. WATER QUALITY BY STEP (OKAYAMA)

Place Removal&

Ratio n

Item No. I No. 2 No. 3 No. 5 Z%

pH 7.9 7.1 5.9 6.7 -i

BOD, ppm 162 47.1 9.8 0.8 99.5

*COD, ppm 109 37.9 17.2 3.4 96.9

*SS, ppm 231 15.5 6.7 1.7 99.6

*NH 4-N, ppm 38.9 35.3 10.9 0.03 99.9

NO -N, ppm 0.23 0.02 0.14 0.03 87.0

NO-N, ppm 0.3 0.1 22.3 24.9 --

T-N, ppm 54.4 44.0 37.3 28.3 48.0

*T-P, ppm 5.16 3.94 3.06 0.26 95.0

Remarks: These data were released by Environment and Health Center,

Okayama Prefecture.

316
COMPREHENSIVE CONSIDERATION ON WASTEWATER TREATMENT BY SOIL

There are some problems in these experiments, i.e., the period of data is

short and the kind of soil was not fully examined in the Okayama experiment,

and coliform and other germs were not observed in the MOC experiment. How-

"* ever, the advantages and disadvantages of wastewater treatment by soil are

generally as follows.

The advantages are:

a. Removes phosphorus completely when the soil is selected

appropriately."'

b. Removes nitrogen far better than activated sludge method.

c. Small amount of sludge produced.

. d. Less energy -~ consumption.

" e. Removes coliform and other germs.

f. Low construction cost.

*" &. Treatment in each household is possible if there is a piece of land

available. . .

h. Easy to maintain.

I. No sanitation or foul odor problems.

The disadvantages are:

a. Unable to treat massively. .

b. Limited by the land space.

c. Treated water quality may fluctuate due to the soil condition. :-.,-,

d. Treated water quality is not as good when the biofilm at the surface

of contact materials is naturally extracted.

e. Not appropriate when the ground-water level is high.

The problems yet to be solved are studying the relationship between

nitrogen removal ratio and soil condition and between nutrient supply method .'

and anaerobic bacteria, and obtaining more data on many items and cases in

various places using various soils.

No

~.-' .'

317

K .--," ,*%'o%'.

. . o .. - - . . . , .. ... -. . ., , . . .. . . . , . . . . .. . -.. .. .. , ., . -, . -° , -#. , -, , -. , - -, - , ,,' , ,4,.
IN SITU STREAM WATER CLARIFYING TESTS

M. Tanimoto and T. Yoshida

Japan Sediments Management Association

ABSTRACT

The advance of river pollution has slowed somewhat since legal regulations on various effluents were

enacted. However, the situation is still serious in

our country. To date many tests and considerable

research have been conducted on river restoration.

However, due to the difficult conditions inherent in

rivers, there are few examples of actual application.

Since lake pollution results from polluted

inflowing rivers, river restoration is indispensable

to lake restoration. A new method has been developed

to clarify stream water in situ. This paper describes

the test results and the method's feasibility.

DCF METHOD

This method of clarifying river water in situ employs a boxlike apparatus

made from steel divided into several chambers with an inclined fibrous plate

in each (Figure 1).

The stream flowing inside the apparatus is subjected to downward flow by

the sloped plate. At the bottom edge of the plate the suspended solids in the

stream are densified. Then the stream line is changed to an upward flow,

where the stream water is clarified because some of the densified solids

remain at the river bottom. An unwoven fibre is spread on the plate which

Fibrous Sheet

Filtration

/ l De n s i fy in g "--

Clarification

Figure 1. Principle of A direct clarifying method

318
acts as a filter. Thus, three procedures, densification, clarification, and ". ".--

7' filtration, are performed inside the apparatus. Therefore, we call it the

. DCF method.

FIELD TESTS

Field tests using a test apparatus were conducted three times in Shakujii

River (Tokyo) and Sanno River flowing into Kasumiga Lake in 1981-1984.

Sanno River

The test apparatus used in Sanno River had five chambers, a total length "y

of 12.5 m, a width of 3 m, and a height of I m (Figure 2).

12 5m

Figure 2. Test apparatus

Figure 3 shows a photograph of the apparatus placed in Sanno River.

Figure 3. Apparatus placed in Sanno River

Figure 4 indicates clearly that the suspended solids settle quite well on

the bottom plate. Figure 5 also shows good sedimentation of solids at the

bottom groove.

The water quality of Sanno River is shown in Table 1. The SS concentrations of the water are 11.6 - 22 mg/. averaging 17.2 mg/. and the BOD concentrations, 4.3 - 13 mg/i., average 8.0 mg/.. Nutrient concentrations are not at

a lower level. The value of N/P is about 10. The reduction of SS concentra-

* tions is significant as Figures 6 and 7 show. The average reduction ratio is

* about 40%. Figure 8 shows the relationship between inf lowing and outf lowing

concentrations of SS.

319

:::.:::

.- ... .. . -.. * . ... ... .. .. * - .. . ~ .: :: : : : : ::,: : :
T...

L-$~ Camera ~ Angle

Figure 4. Settled solids

Camera

I Angle

44I

Apparatus erected

on the river shore

Figure 5. Settled solids at bottom groove

320
TABLE 1. WATER QUALITY OF SANNO RIVER */tihotp

mg/twithut p

Date Time PH SS COD BOD n-Hex T-N T-P

3/7 17:30 7.0 20.0 14.0 9.9 1.5 4.75 0.52

3/9 10:00 7.0 17.0 8.4 6.1 2.8 3.72 0.34 %

3/9 14:00 7.2 22.2 14.5 13.0 3.1 4.31 0.46

3/12 10:00 7.0 11.6 8.0 7.6 2.2 4.46 0.34

3/12 14:00 7.0 14.0 9.3 8.3 3.7 4.05 0.38

3/17 10:00 7.1 17.2 7.2 4.3 1.2 3.83 0.30

*3/17 14:00 7.1 18.7 8.3 6.7 1.6 4.20 0.38

Average 7.06 17.2 10.0 8.0 2.3 4.2 0.39

j~~~~ Facto ReutinRai

BOD 7. 19%110 

Figurae Exml fmaueet 47. 

This sugetsttn most ofthe cnutitents conentaos lare. soube adctonys

esleightly inflncedbythenataats..

FatrRdcto ai

SS 321

BO 9

4T- . . . . . . . . 11%.. . . .

*~- .5% . . . . . . .
120

19

'17

0

March/17: 14* 140

owto

~-12

Mach17 14

01

12

10.0 2 12 I. 1 8 0 2 4 ~

32

-- r...r
VI %7. -

DENSIFYING AND CLARIFYING RATIOS " r..

":

The reduction in SS concentrations clearly results from the downward flow

velocity which accelerates the sedimentation of SS particles. Figure 9 shows

the densifying and clarifying ratios.

0.65 OA O. 0.54 0.66

1.53 233 1.81 1.155 1.1.

Figure 9. Concentrating and clarifying ratios (March/12, 140)

I The mean densifying ratio is 1.67. Note that the sloped plates functioned effectively for the concentration of solid particles instead of the

lower concentrations of SS in the water.

The mean clarifying ratio is 0.56, ranging from 0.47 to 0.66. This means

that 44% of the solids reaching the bottom remain there. The mechanism of the

concentration by sloped plate can be simulated by a hydrological model

(Figure 10). The change of SS concentration under the sloped plate is

represented as follows:

• ac ac a , ~ ~... . 2C a2C

Ux~~~~. x T,-.'.+ ) -

* Ux -horizontal velocity component

Uz - vertical velocity component

w -mean settling velocity of solid particles

Kx - diffusion coefficient in the horizontal direction

Kz - diffusion coefficient in the vertical direction

C - SS concentration

323

...........................................................................
IX

4a5

Figue 1. Hyrolgica coditin o stram nsidaparaus

We ca obtinth exa soltionof Euato sflos.Tepoe au

of etemine Ais frm te folowng uncin

si 0Kx 'h2aXTT - ( 1 3)A LsnCA 2 till 0/44

F~gr Hydrologial 10 condtin of stea insid apartu

sn02a - 1u (U 1 EWz*K/K

3a AU +w Ib K

U- + (U z +x x Kx

(3)

b - b(1 2k)

h H U2 Kz~ + (UZ +W2

2Kz x Kx

Jt KX U2 + (Uz +*W)2 KxS~

2xx Kz

If the SS concentration at the lower edge of the plate is C ,we can obtain

the concentration ratio as follows: A

324
7, 77 7. - 7

of + bh )n n , ..

CA /C An n "(4) ..- .-. ,.

A 0cosAh b Sinx h){vx 1.cos hvr+' 1*. + sinhA z "+Il0

~ n 1 n*~. .n

4xn e-bhX(b -b) + (b - bl)n CO h + (X 2 + bb )sinAnh(5)""

n1 n i nosn nn(5 A"n=2 (," + b){(,z n + b) + (X' + b2)}{(n - b)sin2Anh + 4bA (An + bT)sina'nh)

n n "-'-nShakujii River

Figure II shows the test conditions at Shakujii River (conducted in

* 1981).

@-- .. -- --- 0 1 . 1 -- @-:

." . . '

13-

1.400

1.900 -...

Figure 11. Test condition at Shakujii River

At this time, the mean densifying ratio was 1.3. Figure 12 indicates its

computed curve.

From the simulation it was found that the diffusion coefficient In the

vertical direction (Kz) had a high value of about 200 cm2 /sec. This is

apparently a major cause for the promotion of the sedimentation.

CONCLUSIONS

The DCF method has the following attributes: toa. No energy.

b. No labor.

c. Very simple construction.

325

. . . .: . . . .- . : .. ' : . . . : . . , . . : - . : ' : : .: . . 1 , . . . -
1.78

& A~~Kx/Kz=120 ~A

t4 -\ .

1.2

k ~1.1 _;

1.0

100 200 A0 OO 00 OX 00IOX -'":

-Kz (cm 2 /SeC)

Figure 12. Computed curve of densifying ratio

d. Very cheap investment.

e. Very high clarifying capability.

In general industrial water treatment, a filtration procedure is applied to

the clarification of water having less than 20 mg/L SS concentrations.

Clarification by the DCF apparatus lies in this range of industrial filtration. It is reasonable to note that we attained good results when comparing

industrial filtration techniques with the simple device of the DCF method.

Consequently, the feasibility of the DCF method seems to hold promise.

000

-- 0- 8- .% 

DCF

Sand Filtration ...

In the application of the DCF method to actual rivers, the most difficult

problem may be countermeasures for flood flows. Preparing a by-pass flow is

one safe method.

.-. . . .. . . . 326...
Flood Flow

DCF Apparatus

* The preceding tests were conducted as the first step in a major project

of the Ministry of Construction regarding lake and river restoration.

327
I .-. " ,,, . -

PURIFICATION OF lIMO RIVER BY THE GRAVEL CONTACT METHOD

M. Kobayashi

Director

River Adjustment Division, River Department ,

Kanto Regional Construction Bureau

Ministry of Construction

1-3-1 Ootemachi, Chiyoda, Tokyo, Japan 100

T. Kiriku

Director

Keihin Work Office, Kanto Regional Construction Bureau

Ministry of Construction

2-18-1 Tsurumi-chuo, Tsurumi, Yokohama, Japan 230 1 _L

INTRODUCTION

The Tama River originates from the Kasatori Mountains in Yamanashi

Prefecture and joins with its tributaries: the Nippara, the Aki, the Ass, the

Nho, and the Hirase. It then runs along the border between Tokyo and Kanagawa

Prefecture and flows out into Tokyo Bay (Figure 1). This river is a typical

urban river in Japan. From the earliest days, the Tama River has played an

important role in flood control and irrigation in the socioeconomics and

culture of the metropolitan area.

As urban areas and industries continue to develop in the middle and lower

basin, it becomes necessary to note the importance of preservation of its natural environment, not to mention flood control and utilization of the water.

Therefore, the Master Plan of Environmental Control of the Tama River was presented in March 1980. In the plan, efficient use of the river terrace and

good conservation of the natural environment are coordinated.

One of the main characteristics of this plan is the restoration of abundant and clear streams. In reality, pollution of the Tama River began in the

latter 1950's and has progressed with urbanization of the river basin. The hJC

main cause of river pollution is the discharge of domestic and industrial

wastewater from the middle and lower basin area.

The Nho River, a tributary of the Tama River, is polluted heavily by such

wastewater and is causing deterioration of the water quality of the main river.

The Nho River Purification Facility intends to help improve the Tama River

water quality by purifying the Nho River and discharging the purified water to

the Tama River. The purification method called "Gravel Contact Purification"

(herein-after referred to as GCP method) is used to artificially raise the

natural purification potential. Since the Tama River has a wide river terrace

and an abundant gravel resource, this method is applicable to the purification

facility at Nho River.

328

- ~t *
464

F to

-H

4-A

329~__
Application of the GCP method on the Nho River is the first practical use

of the method in Japan. The polluted influent water from the Nho River will

flow through the gravel laid under the terrace of the Tama River, and, as a

result, organic matter in the water will be removed.

The construction of the Nho River Purification Facility, located at offKamata, Setagaya District of Tokyo, upstream of Shin-Futako Bridge, began in

November 640 1981 and was completed 2 years later in July 1983 at a cost of million yen.

BACKGROUND OF THE PURIFICATION FACILITY'S CONSTRUCTION

For many years, the Tama River was always clean and was treasured by the

people. However, after World War II, in the middle and lower basin areas,

rapid urbanization caused a sizable discharge of the domestic and industrial

wastewater to the river, and, simultaneously, the upstream clean flow was

removed at the Hamura Intake Dam. Consequently, the water quality in the

middle and lower basin areas began a rapid deterioration in the first half of

1960's, augmented by the increasing portion of domestic wastewater (Figure 2).

In the following years, dredging of the settled sludge on the river bottom, a

work for purification, was carried out and gradually improved the water

quality.

In the middle basin areas, however, the improvement program including

construction of the sewerage system could not cope with the increasing domestic

wastewater discharge. The worst water quality was recorded in 1970 and, although the situation has improved slightly since then, the water quality is.-

still less than the environmental standards tolerance. The river's quality

ranks in the worst 10 of 109 major (First Class Category) rivers in the

country.

The improvement of river water quality can be achieved, in principle, by

reduction of the inflowing pollution loads. In the case of the Tama River,

pressed by the request for improvement, the reduction of pollution loads has

been envisaged to promote sewerage systems construction and strong enforcement

of industrial wastewater control. As a result, the increase in pollution has

slowed in some areas, but in most areas the effects have not yet been realized.

The Tokyo Metropolitan Office and the municipalities located along the

river are primarily promoting secondary treatment sewerage systems. In a

river like the Tama where the wastewater flow is relatively high proportional

to the river's base flow, improvement of the water quality by dilution is not

very effective, because the total pollution load in effluent after the secon- . dary treatment is still substantial, even when the treatment efficiency of the

sewerage system has been raised. That is, the discharged effluent becomes a

large source of pollution.

Therefore, introduction of tertiary treatment will make improvement of

discharged effluent possible, but many years and huge expense is incurred before completion. Early execution of the tertiary treatment cannot be expected.

In order to improve the water in Tama River under such a situation, it is

necessary to devise a countermeasure, along with the construction of sewerage

systems. The river control authority, the stimulus for concentrated

330

A. %

'.-'."...'-r%-' "% ..-' -'. . '% ," .-.......................................................................................- o. -. •• . ....-. "* . -.-
a - - .5 - - - .- - - --. 4 .

00 W -5~

r-~~ I-'O

4*3

-KS

-5-,) 00

-331
improvement efforts, has Judged that those efforts would achieve sufficient V

technical effects. Besides, the existence of a river like the Tama in an

urbanized area is valuable for the inhabitants living there. Making the river

as clean as possible, regardless of the environmental standards as a sole

criterion, shall be pursued.

With this historical background, the Nho River Purification Facility is a

practical installation that employs the direct purification process in which

the pollution load flowing in a river is reduced within the river site.

THE GRAVEL CONTACT PURIFICATION METHOD

The GCP method is a process which artificially improves the natural puri- ..*

fication potential of a river. Accordingly, the mechanism will be explained

in relation to the natural purification potential.

Mechanism of Purification

A river is polluted by receiving inflowing pollutants. However, as the

river water flows downstream, it is gradually purified by the various inherent

functions, called the river's "natural purification potential." This natural

purification potential is broken down into the following four operations:

a. Dilution.

b. Settling and adsorption.

c. Filtration.

d. Intake and decomposition by organisms. '

As the river current runs downstream, the pollutants settle and are adsorbed

to the river bed, or organisms living in the river bed take in the pollutants,

and the river is gradually purified. In this type of purification, the main

characters are the living organisms and the river bed's gravel, especially the

film covering the river bed's gravel. This slimelike film is called "biofilm"

and plays an important role in removing pollutants from the river. "

Method

Natural purification of a river requires a long distance and a long time,

in principle, to be effective, and when a river is highly polluted, for

instance beyond its own purification potential, the pollution will not diminish even as the river flows downstream. For such cases, some means to raise

the purification potential must be found.

Increasing the volume of gravel covered with living organisms in the river .

bed may be one solution. As shown in Figure 3, if a river bed I sq m in area

is counted as an effective unit, then another bed 5 sq m in area, composed of

five layers of 1 sq m in a vertical pile, will be effective as five units. A

layer I cu m in volume of gravel packed with 5-cm-diam particles presents

about 100 sq m of surface area. If such a large surface can act effectively

in settling/adsorbing the pollutants and attaching the biofilm, the purification potential will increase markedly.

332
A RIVER ACCUMULATED RIVER BED TIlE GCP METiOD

_I X 1 .-.... ..

A- -is I-s--I

Pollutants are re- A wider surface Contacting surface

moved by the natu- area increases the area is increased by

ral purification purification capa- flowing water into

capability on the bility in the same gravel bed so that

surface of the distance of flow. the purification

river bed. capability is

accelerated.

Figure 3. Accelerating purification capability of the GCP method

A purification method in which an artificially increased contact area

removes the pollutants by settling/adsorption to the surface and by intake/

decomposition of the living organisms attached to the surface is called "contact oxidation." Various methods using different contact materials to

increase the contact area have been devised and practiced. The GCP method is

one which uses gravel as the contact material.

Experiment of GCP method

Beginning in fiscal year 1973, the experiment at Tama River was conducted

to study onsite purification methods to improve the river's water quality by

utilizing the wide river terrace and abundant gravel resource which characterize the river for purifying the polluted water. Figure 4 shows the experimental installation.

The installation was packed with gravel collected at the river terrace,

and different effluents of secondary treatment, honey-comb treatment, and

sedimentation treatment of sewage water were tested for (a) effectiveness in

removing BOD and achieving denitrification, (b) the clogging effect of gravel

voids, and (c) the sludge settlement.

The results were as follows:

a. Removal rate. Expected removal rates of 60 to 90% for BOD and 80 to

95% for SS were confirmed. The denitrification rate was small.

333

* .* .- . *+ ° ". , .'. . , ,.21
6 - -. -' L.- 1.-.

P.

H Aeration Tank

3m 3m '5m IM

DistributObevtoGalr

HJ E Gravel Bed A-1

Discharge

O ,0 10 5 0~s.0 02 05 *02

14.8

40A Q 3.0 0.3 3.0 03 3.0 0.3- 3.0 0.3 103

Figure 4. Experimental design for the GCP method

b. Requirements affecting effectiveness.

(1) Retention time--The removal rates of organic substances like BOD

and SS change depending on the retention time. For instance,

1 hr for 70% removal of BOD and 1.25 hr for 75% vere found to be

necessary (Figure 5).

(2) Flow length in gravel bed--To attain a steady effect of

purification, 15 to 20 m of flow length was found to be

necessary (Figure 6).

334
100

00 0 0

000 00

/8 0 0

a 750 0k50 0 0~ 090

0

25

20

060 1 

25

0 10 5 1 20 2503 35 40 5 5

Figur 6.- chngny itaceo 1OD fo

133

-r . . -0 . .
7.1,

OUTLINE OF NHO RIVER PURIFICATION FACILITY

Design Criteria

Considering the economical feasibility, the retention time of 1.25 hr and

the flow length of 17.5 m for the target of 75% removal of BOD were selected

- for the design (Tables I and 2).

TABLE 1. DESIGN VALUES ,a.

Item Design Values Remarks

3 Basic flow of Nho River 1.15 m /sec Low flow of Nho River

Treatment flow 1.0 m3 /sec

3 Fishway flow 0.15 m /sec

BOD of Nho River 13 mg/iSS of Nho River 16 mg/i

Removal rate of BOD 75% 1.25-hr retention time

Removal rate of SS 85% 1.25-hr retention time " Sludge storage time 5 years

Description of Flow

The facility is composed of two parts, the intake dam and the gravel bed.

The gravel bed is constructed 1.7 m underground in the river terrace of the

Tama, not to be submerged by flooding. The intake is an easy-handling

inflatable dam made of rubber-coated fabrics selected for the flood's -..

uninterrupted flow.

The water of Nho River raised by the dam forces flows through the inlet

pipe into the gravel beds (92 m wide, 148 m long, 1.6 m deep, 8 beds) and

spreads by the perforated distribution pipes. The water, flowing in the bed

by gravitation, is purified and collected by the perforated collection pipes

before being discharged (Figures 7-9).

Advantage of Facility

The advantages of the purification facility are as follows:

a. Saves resources. The main material, 21,400 cu m of gravel, was

available at the construction site of Tama River.

336

*4~ * * . .'. ..--- .-.....
-', .J.t "

TABLE 2. OUTLINE OF THE GCP PLANT

Item Values Remarks

Gravel Beds

Effective depth 1.5 m 1.6-m bed thickness

Shape of bed 92 m wide x 1.6 m thick x 17.5 m 8 beds

long

Size of gravel 20-150 mm

Void of gravel Approximately 35%

Area of beds 1.36 ha (92 m wide x 148 m long)

3 Total volume 21,400 m.

Intake Dam (Movable Rubber Dam)

Dam height 2.45 m

Width of dam 26.3 m of top

16.5 m of bottom

Material of dam Ply-rubber (Chloroprene) 12.5 mm thick

Operation system Automatic deflation by sensing

water level

Attached devices Water level meter Monitor and record

Alarm device

b. Saves energy. The difference of levels at the intake and discharge

points is utilized for the gravitational flow and no energy is input

to the system.

c. Maintenance free. With ordinary purification systems, the

maintenance problems including the disposal of generated sludge are

troublesome, while with this facility the sludge is decomposed and

deposited naturally. This makes the system maintenance free for

several years and less sensitive to a drop in efficiency.

d. Utilization of surface area. When the gravel bed is covered by

earth, the surface can be used for recreational purposes such as a

playground and plaza for the people; this is a marked advantage.

337

~~~. .. . . . . .- . .... °.
% %A

opera?

ft ... .

'seepage Pipe

P r us~ pipe) .

- ~ Gravel# Beds

APermneatWJ Pipe'- .

L/(poroudlPipe)

Figure 7. Schematic of the GCP plant

PURIFICATION IN NHO RIVER FACILITY

Intake Dam

The rubber-coated inflatable dam raises the river's level by about 2.45 m. P Large suspended solids (SS) are removed by settling in the pond. When inorganic SS are largely contained in the runoff from rainfall and the water is

338
18 500m _______-_

7.1i 300m

.. 0,,, ooo/ /-o __ 0% _____ V-7

.--.. Gravel Bed ( o"

Permeation Pipe Seepage Pipe

(porous pipe) (porous pipe)

Figure 8. Cross-sectional view of a gravel bed

led to the gravel bed, it will shorten the service life of the system. In

such a case, the dam is flattened automatically so that the turbid water is

kept away from the facility.

Gravel Beds ,.__ '

The pollutants contained in the flow are removed by contact settling/

adsorption in the beds, while the organisms in the biofilm covering the gravel

surface contribute to purification.

Outlet Work with Sill

The DO in the inflow is consumed in the purification process by the gravel

bed organisms. At the outlet, the discharging effluent is re-aerated to recover the lost DO by falling over the weir.

ROLE AND EFFECT OF NHO RIVER PURIFICATION FACILITY

The Nho River, beginning in the Kokubunji City area, flows through the

densely populated Koganei City, joining with the Sen River before it flows

- into the mainstream of the Tama River at a location off-Kamata, Setagaya

District of Tokyo Metropolis. The Nho River, as one of the most polluted

tributaries of the Tama River, is a source of pollution raising BOD concentration of the Tama River in the middle basin areas.

3 The Nho River Purification Facility was planned to treat 1.0 m /sec, of

3

the 1.15-m /sec flow in Nho River, and remove 75% of the BOD and 85% of the

SS. For instance, when the Nho River water contains i3 mg/i BOD and 16 mg/ .

SS and the facility is working according to plan, it will improve the water to

3.25 mg/ BOD and 2.4 mg/ SS. The result is that the mainstream pollution of Ithe Tama River will be decreased by about 10% by dilution of treated effluent

(Figure 10).

TRACK-DOWN INVESTIGATION OF NHO RIVER PURIFICATION FACILITY

The outline of the track-down investigation for 13 months, from start-up

to July 1984, will be described here.

339

- . ...........
'.=-"-"-" ". -.- "-. :. - ' -"" -- -". -r" - . . rr r ,rr - r ~ ~ z r y U-.

'II o

RIVUR WATER

~, ~ INLET WORKS

.".-'I

: SInlt Sill

:1Fishay Scree

Grit Chamber

........... ".......... ..................................... .

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

PURIFICATION WORKS

Distribution Box .

Figure 9. Flowcart of GCP plant •I S- .. .

_ _ _ ____ _ _ _.

IDistribution Pipes

I Gravel Beds

Collection Pipes

Collection Box

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

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

OUTLET WORKS :

Outle Sill

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

Discharge

340

io o.

....................................... o
Intake Dam ( ) Predicted BOD 09/0)

GCP plant %e..

the Tama River (10.5) (9.8)

Figure 10. Predicted BOD after construction of the GCP plant

Operation of Facility

During 13 months of operation after start-up, the dam's automatic deflation took place 24 times due to substantial rainfall. All cases registered a

precipitation exceeding 10 to 20 mm/day, according to Setagaya District's

record. In addition, 24 intentional deflations of the dam, unrelated to rainfall, were conducted for construction, experiment/inspection, and cleaning of"--

the intake equipment. Excluding the period of construction, the facility was

operational for 272 days, showing a 77% efficiency.

Nho River Flow

3 The flow fluctuated between 0.16 and 1.50 m /sec, making the average

0.60 m 3/sec, which was about 50% of the design value. As for the overall

changes, the average flow of 0.79 m 3/sec in July-November 1983 fell to

3

0.47 m /sec, 60% of the mentioned figure, in December 1983-July 1984 period.

The noticeable decrease after December in the previous year was obviously due

to low precipitation (Figures 11 and 12).

Change of Treated Flow

The inflow to the beds, or the treated flow, during the period was 0.14

3 3

to 0.83 m /sec, an average of 0.41 m /sec equal In 40% of the design value.

3 3

The fishway flow was 0.01 to 0.44 m /sec with an average of 0.17 m /sec.

Decreased flow in the Nho River due to low rainfall affected the treatment

facility, along with the unexpectedly large quantity of floating matter such

as garbage and weeds which clogged the inlet screen to the gravel beds.

Water Quality of Nho River

The water quality sample was taken at a spot near Nogawa-Suido Bridge, . .

700 m upstream of the intake where the backwater's influence was minimal. 1..

Figure 13 shows the monthly average from July 1983 to July 1984. The BOD for

July to November 1983 closely followed the planned BOD value of 13 mg/£, but

from December 1983 to May 1984 it jumped above the planned value.

341
1.01

0- River Flow

- - Treatment Volume

0.8.

E

x 0.4

0.2

7 8 9 10 11 12 1 2 3 4 5 6 7

1983 1984 month

Figure 11. Monthly change of river flow of the Nho River and

treatment volume by the GCP plant

300

1983-1984

- 200 -- - - - - - - - -

~ a verage year

E/

0

7 8 9 10 11 12 I 2 3 4 5 6 7 -

month

Figure 12. Change of monthly rainfall (at Setagaya Meteorological Station)

342

Le -- d. p C.~ .
%*'

30

S6

04

0

50

30

40

- 303
Ir 0,oe'%

The SS values from July to December 1983 were below the planned value of

16 mg/1 and rose higher than the 20-mg/i level from January to June 1984. An

extraordinary high value recorded in March is thought to have been caused by

construction work at the upstream river bed.

Water quality generally deteriorates in winter as the low water temperature makes organisms less active in the river bed and in widely used domestic

wastewater purification tanks, resulting in reduced natural purification potential. The main reason for the continued high values in May/June is the low

rainfall, about half that of an ordinary year.

Effectiveness of Nho River Purification Facility

The expected effect of purification in the facility is due first to settling in the ponded water and second to settling/adsorption and biochemical

oxidation in the gravel beds. Table 3 shows the results of water quality analysis of the samples taken at the river and at the inlet and outlet of the beds,

represented by the monthly average values.

Comparing the river water with the inlet water, one can see the effect of

impoundment, and the comparison of the inlet water and the outlet water shows

the effectiveness of purification by flowing through the gravel beds.

- Purification through Impoundment by the Dam

The BOD in the Nho River of 9.3 to 31.5 mg/i with an average of 19.0 mg/i

changes to 6.9 to 17.4 mg/i with a 12.0-mg/i average in the inlet. The SS

values of 6.0 to 67.1 mg/i with a 20.8-mg/i average in the river is reduced to

4.3 to 25.7 mg/L with 9.7 mg/i average in the inlet.

The water quality of the Nho River itself fluctuates substantially. The

recorded averages of BOD and SS in the inlet, 12.0 and 9.7 mg/i, respectively,

are rather lower compared to the design values of 13 mg/i for BOD and 16 mg/i

for SS, possibly resulting from the stabilizing effect by impoundment.

Purification in Gravel Beds

Water quality at inlet and outlet. Figure 14 shows the monthly change of

*, water temperature, DO, SS, and BOD at the inlet and outlet of the gravel beds.

For water temperature, the highest value of 28.3*C was recorded in August

* 1983 and the lowest value of 5.9*C in January 1984 during the survey period. - There was no noticeable difference between the inlet's and outlet's temperature.

Regarding the monthly average DO, the highest value was 10.8 mg/i, the

lowest value was 1.5 mg/i, and the average was 6.1 mg/i. Low DO was

experienced in May to July 1984 and, in the worst cases, DO dropped to zero.

The extremely low DO results from consumption by the settled sludge at the

intake dam's impoundment, under the low flow of Nho River containing high BOD

and SS concentration during the scarce rainfall period of those months.

The GCP method requires dissolved oxygen in water since purification is

promoted by contact oxidation of the biofilm covering the gravel surface. Low

. DO will certainly adversely affect maintenance of the purification capability.

344

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outlet of the gravel beds

346

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-S-
The DO in the gravel beds was kept more or less above 1 mg/t in July to

December 1983, but dropped to 0 to 0.5 mg/1 when BOD was maintained at a high "'.

level.

As mentioned before, an outlet sill was installed at the effluent discharge point and, because of it, DO of the discharged effluent was restored to

an annual average of 4.8 mg/i.

The inflowing BOD was close to the design level of 13 mg/i, as the highest

was 16.7 mg/i, the lowest 7.2, and the annual average 12.0 mg/i. When considering the entire survey period, a tendency was found in that BOD was high in

winter and low in summer, as generally seen with rivers in urban areas of the

country.

The high BOD recorded from April to June 1984 is thought to be unusual.

BOD in treated water averaged 4.9 mg/i for the 13 months. Although higher

than the design value of 3.25 mg/i, it was still acceptable. However, from

March to June 1984, the value was approximately 7 mg/i. During this period,

the effluent was characterized by 55 to 75% of the discharging BOD being dissolved BOD (D-BOD) which needs an ample supply of dissolved oxygen. D-BOD can t ' .*

be removed only through decomposition by aerobic organisms, while BOD contained

in suspended matter is removed by settling. Incidentally, DO was consumed

completely in the gravel beds. In fact, anaerobic conditions in the beds were

so extreme that the water generated the odor of hydrogen sulfide. As the

inflowing DO was restored, the odor disappeared.

The inflowing SS showed an annual average of 9.7 mg/i, a value lower than

the design value of 16 mg/i. The effluent was approximately 3 mg/i, except in

the start-up period.

Effectiveness of purification. The effectiveness of purification was

studied for four successive periods after 13 months of operation (Table 4):

(a) the initial period, (b) a normal operation period, (c) a low water

temperature period, and (d) an abnormal water quality period.

For the initial period, 2 weeks after start-up, the clay and silt

attached to the gravel were being washed and the biofilm of organisms was in

the development stage. This condition caused low removal effects.

When the start-up period was over, the biofilm was formed and became

effective in adsorption and settling (normal operation period, July 1983-

November 1983). The inflowing BOD and SS were, on the average in the period,

9.3 and 9.1 mg/i, respectively, lower than the design values, and the effluent

BOD and SS were 2.9 and 2.7 mg/i. From these figures, the removal rates for

BOD and SS are 68.8 and 70.3%, respectively.

Starting in December 1983 (low water temperature period, December 1983-

March 1984), the water temperature dropped below 10*C and the inflowing water

quality worsened. The average D-BOD was especially high, 9.5 mg/i. BOD and -.

SS removal rates were 63.8 and 69.7%, respectively.

347

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348
April to July 1984 was categorized as the abnormal water quality period.

In most years, however, the river water quality improves as the days proceed

in this season. However, the Nho River in this season was, as far as water

quality was concerned, very similar to the winter season's. Moreover, as the

water temperature rose, the consumption of DO increased causing a reduction in

inflowing DO. The average BOD and SS values of the inflow were 13.4 and

8.6 mg/1, respectively, and the removal rates were 45.5% for BOD and 60.5% for i-; ss.

BOD in the effluent was remarkably high (7.3 mg/i), and 5.1 mg/t of the

BOD was D-BOD in nature. This showed that, because of the scarcity of the

inflowing DO, even after all DO had been consumed in the gravel beds, D-BOD

was not removed from the water.

In the last days of this period, the rainy season started and the river

water quality improved. Operation was restored to normal as the consumption

of DO in the impounded area decreased.

Effect of Recovering DO by O.tlet Sill

The aerobic organisms oxidize and decompose the pollutants such as organic '.

matter in the gravel beds, consuming existing DO. For the normal life of a

fish, greater than 30% saturation ratio of DO (about 3 mg/1) is said to be

required. This necessitates the recovery of DO for the treated effluent.

In the facility, reaeration of the effluent by the 1-m-high outlet sill

is helping the recovery of DO, as summarized in Table 5 and Figure 15.

TABLE 5. REAERATION EFFECT OF OUTLET SILL

DO, mg/i

Inner Beds

Inlet (8.5 m) Upper Sill Down Sill

Average 5.7 1.3 1.4 4.8

Maximum 9.2 4.5 4.7 6.5

Minimum 0.5 0.0 0.0 2.1

The average of 5.7 mg/A DO at the inlet dropped to 0 to 4.5 mg/1 with the

average of 1.3 mg/i as it was consured in the beds. The effluent recovered DO

to 2.1 to 6.5 mg/i with the average 4.8 mg/i by the outlet sill, and the process proved its worth.

349 I ..... '
, -- e- - Down Sill .

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.. ~Figure 15. Effect of reaeration by outlet sill"-"

EFFECT OF IMPROVEMENT ON TAMA RIVER MAIN -. * To determine the facility's effect on the Tama River's water quality, the

water quality at both upstream and downstream points of the confluence, and

both before and after the operation, were compared. The selected points upstream and downstream were Tama-Suido Bridge and Futako Bridge, respectively.

The difference in BOD at the two points before the operation was 2.6 mg/i

as a 5-year average. One year after the operation, the difference decreased

to 2.0 mg/k as a year's average. The decrease of 0.6 mg/1 equals approximately 9% of the value at Futako Bridge, the downstream point of the confluence. In the original plan 10% was the target; therefore, the facility was as

effective as planned.

OUTLINE OF MAINTENANCE WORKS

Inspection on Patrol

The patrolling operators inspected the intake dam, water level meter, and

recorder periodically. As the facility uses few mechanical parts, the inspection work was simple and quickly completed. A telemeter system is used to

detect the water level at the site and signal the readings to the supervisor

at the Keihin Work Office.

350 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
II

Intake Dam

The dam is automatically deflated by sensing the rising water level.

After the water level lowers to a certain level the dam is inflated by onsite

activation of the operator. Though the operation can be completed in 30 min,

I to 2 hr is needed before the impounded water starts flowing into the gravel

beds and an additional 2 to 3 hr is needed before the effluent resumes

discharging.

Screen cleaning

The most troublesome maintenance work of the facility is cleaning the

inlet screen. In the worst case, the cleaning work was carried out weekly. , . -

The seasonally changing garbage removed by screening is composed of:

a. PVC bags, waste papers, foam styrene, and empty bottles and cans

throughout the year.

b. Fallen twigs and leaves, mostly from October to December.

c. Cut weeds, mostly in July and August.

d. Aquatic plants, mostly from September to March.

As some garbage is thrown into the river with obvious intention, education and

public relations programs to obtain the public's cooperation are necessary,

not only for maintaining such facilities, but also preserving the river's

c leanline ss.. - ;

To prevent inflowing floating debris, a few tests were conducted. One

was installing a skirtlike board which intended to cover 50 cm of depth below

the water level. It did not collect much. Another was placing a cagelike

screen or a net behind the bar screen. It collected too much, clogged, and

hindered the flow. At present, these are used in combination to control

inflowing garbage and remove collected debris easily. However, improvement is

needed in garbage removal.

After 13 months' experience, the maintenance and prevention needs are: ..

a. Removing screened garbage.

b. Coping with the accumulated garbage at the dam pond to preserve

aesthetic scenery.

c. Preventing foaming at the outlet.

d. Preventing scum and odor generation at the dam pond.

The maintenance work is concerned more with the fringe matters than with

the facility itself, which is peculiar to the general concept of maintenance.

351

-* ..?.z.
LOW INFLOWING DO AND ITS ADVERSE EFFECT

From the end of May to the middle of June 1984, the odor of hydrogen

sulfide was generated in the effluent of gravel beds and sulfur bacteria

growth was so remarkable that a stretch of river bed 100 m long downstream of

the facility was colored white.

A quick investigation revealed that: -

a. Due to the slight rainfall, the rubber dam was deflated only

infrequently and the deteriorating water quality of the Nho River

caused an accumulation of sludge on the bottom of the pond.

b. A sudden water temperature rise at the end of May stimulated DO

consumption of the deteriorating river water and sludge in the pond.

As a result, the inflowing DO to the beds was nearly zero.

c. The lack of inflowing DO made the gravel beds extremely anaerobic and

generated hydrogen sulfide.

d. The effluent containing hydrogen sulfide was discharged to the river

and encouraged the growth of sulfur bacteria, changing the color of

the river bed. At first the river bed changed to white by the growth

of sulfur bacteria under anaerobic condition, and after a few days,

regain of outflow DO changed the color of the river bed to black.

e. The shortage of DO obviously caused the anaerobic condition of the

gravel beds. If DO is preserved in the inflow, the generation of

odor by hydrogen sulfide can be prevented.

f. The BOD and SS percent removal was lowered somewhat, but the purification function was only slightly affected.

These conditions resulted in a study to find a solution and to determine

countermeasures including installation of an emergency aerator. In practice,

however, the problem was solved naturally. The rainy season started at the

end of June and improved the pond's condition and inflowing DO and, as a

* result, the unpleasant odor and white color of the river bed disappeared.

GENERATION OF SMELL AT THE POND b

At the end of May 1984, a large amount of scum appeared on the pond and

was gathered by the wind, raising a rotten smell. The direct cause was sudden

decomposition of the inflowing organic matters and the sediments in the pond.

. The smell has stopped now because of the improved flow in Nho River.

The operation practice of the intake dam and means to prevent accumulation

* •of the sediments are being studied at present.

CONCLUS IONS

Since this was the first practical installation of the GCP method in the

country, the expectation of finding new facts and learning new experiences has

co-existed with an uneasiness of unpredictable happenings during the 13-month

.S 352

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° .

°.°° °'°..
• I.*ji... .I 

study. However, as anticipated, the facility has proved its expected usefulness without much maintenance. On the other hand, the burden related to cleaning the inlet has been greater than foreseen initially. Future improvement is

needed for this aspect.

Also unexpected were the appearance of large amounts of scum in the pond

and the generation of hydrogen sulfide odor from the gravel beds. Even though

the facility is operating normally at present, unexpected happenings may still "". -

occur, partly due to the lack of experience. Hopefully, in the future,

improvements and better maintenance will make the facility even more

effective.

For the promotion of the GCP method and other methods of river water

quality improvement, the reader's comments and advice are welcomed.

Photos 1-4 show the Nho River Facility.

353

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Photo 1. The purification facility at Nho River

ztr'-ZZ

Photo 2. Experimental installation of GCP method

354

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OF DREDGED MATERIAL

THE LONDON DUMPING CONVENTION RE-EXAMINED

H. R. Haar1. .

Board of Commissioners of the Port of New Orleans

P.O. Box 60046, 2 Canal Street

New Orleans, Louisiana 70160

ABSTRACT

Members of the International Association of Ports

and Harbors (IAPH) and the American Association of

Port Authorities (AAPA) have, since 1979, been

actively engaged with various activities involving the

London Dumping Convention. Their continued success in

developing international principles and practices for

the ocean disposal of contaminated and non-contaminated

dredged material will ensure that national and international port views are taken into consideration, and

that such views influence policy decisions being made.

Many problems have arisen over the years in regard to

the London Dumping Convention Treaty requirements and

United States implementing laws of this treaty for

ports, not only in the United States, but in other

areas of the world as well. In response to these

problems, it has been necessary for IAPH and AAPA to

engage the services of scientific and legal professionals to assist in examining and proposing viable

solutions capable of bridging differences between

ports' interests worldwide and those of the U.N.

treaty organization. The results of this mission--

addressing past activities and current issues--are

presented in the following sections of this paper

which expands on my November 1982 presentation at the

Eight U.S./Japan Experts Meeting entitled "Rescuing

the Ports - An Update."

INTRODUCTION

Ports throughout the world play a major role in a nation's economy. To

remain open to waterborne traffic and commerce, most ports must conduct

periodic construction and maintenance dredging activities. Such work requires

suitable means of dredged material disposal. The ports of many nations, and,

particularly, ports in the United States have experienced difficulty, delays,

and increased costs in conducting necessary dredging. Underlying these difficulties are the need to dispose of dredged material into ocean waters and-.. -

357

.. ...... 
worldwide concern over the impact of ocean dumping on the environment. Disposal practices of many world ports are determined from the requirements

established in the London Dumping Convention (LDC).

In the United States, the environmental movement of the early and midseventies began exacting its toll on the ports of the country in the late

seventies. This toll is in the form of time delays in obtaining dredging and i/iA.

dredged material disposal permits, denial of permits, delayed capital investment improvements, increased investment and operation and maintenance costs,

and low revenues. To counter these impacts and to seek state-of-the-art .a

practices in dredging and dredged material disposal activities, both the

American Association of Port Authorities and the International Association of

Ports and Harbors established ad hoc dredging committees. Since late 1979

these two organizations separately and jointly have pursued similar goals to

obtain political recognition and acquire influence to alter United States

legislation and international convention as established in the LDC.

Decisions governing ports and port operations engaged in international

trade must be made in the overall public interest and welfare. These decisions must not be excessively hampered by environmental considerations alone. **%\-..

Achieving organizational goals will require continued effort, organizational

funding, and exploitation of opportunities to tell the story.

LDC BACKGROUND HISTORY

The London Dumping Convention was enacted in December of 1972 as a result

of the growing realization by the nations of the world that the ocean did not

have an endless capacity to assimilate man's waste and still regenerate

natural resources. It closely paralleled legislation adopted several months

earlier (October 1972) in the United States to establish a program for the

control of ocean dumping in domestic waters and territorial seas. The LDC was

opened for signature on December 29, 1972, with 27 states signing that day.

The LDC entered into force on August 30, 1975, when it was ratified by the .

required number of 15 states. To date, 53 countries have ratified or acceded

to the Convention.

The LDC relies heavily upon implementation by member states according to

their national authorities. It is implemented in the United States through

the Marine Protection, Research, and Sanctuaries Act 1972 (MPRSA) which

required only minor amendments to ensure consistency with the LDC. The key

provisions of the LDC relate to the prohibitions and permit requirements set

forth in Article IV, and its accompaning Annexes, I, II, and III. Article IV

(1)(a) prohibits the disposal of certain "blacklisted" substances set forth in

Annex I (e.g., mercury, cadmium, organohalogens, petroleum products, and high

level radioactive wastes) unless, in most cases, the substances are present as

only "trace contaminants" (Annex I, para. 9) or are "rapidly rendered harmless" upon disposal (Annex II, para. 8). Article IV (1)(b) provides that for

the "grey list" of substances described in Annex II, "special care" in disposal is required. Annex II substances can only be disposed under a "special

permit." Under Article IV (1)(c), all other substances are to be disposed

under a general permit. The factors specified in Annex III are to be considered in the issuance of both general and special permits.

358
The LDC does not specify particular standards and criteria that must be

applied in determining the "trace contaminants" and "rapidly rendered harmless" questions under Annex I. That is left, by and large, to the decisions

of national authorities. "Interim Guidelines" have been adopted to serve as

"guidance" for the interpretation and implementation of paragraphs 8 and 9 of

Annex I, but they establish no fixed standards. In the early years of the

Convention, the Contracting Parties appear to have construed the "trace

contaminant" provision of paragraph 9 as vroviding a categorical exclusion of .i*

dredged material from Annex I. The original draft guidelines for the implementation of paragraphs 8 and 9 adopted at the Second Consultative Meeting in

1977 contained an exclusion for sewage sludge and dredged spoil. They were

endorsed in principle by Contracting Parties for further consideration as a

priority item. At the Third Consultative Meeting in 1978, Contracting Parties

adopted final Interim Guidelines. However, a substantial change was made.

Test procedures for determining "trace contaminants" were extended to dredged

material. This departed from the original understanding of the dredged material exclusion endorsed in principle by Contracting Parties the previous year.

This action at the Third Consultative Meeting created a serious dilemma

for many ports. As a result of growing industrialization and increases in

water-borne trade and commerce, many ports find that their harbor sediments

may contain substances listed in Annex I in varying degrees. This may present

special problems for those ports which rely upon ocean disposal of dredged

material for continued operation. The critical determinations are those

relating to the "trace contaminants" and "rapidly rendered harmless" questions. If an especially stringent standard is applied, it may trigger the

Annex I prohibitions and prevent ocean disposal of the dredged material--even

at the expense of continued port operations.

Concerns of this very nature began to arise shortly after adoption of the

Interim Guidelines at the Third Consultative Meeting. In 1979, environmental

groups in the United States insisted that Annex I barred the ocean disposal of

dredged material at the Port of New York-New Jersey and at the Port of Lake

Charles, Louisiana, because the dredged material allegedly contained Annex I

substances that exceeded "trace contaminant" levels. It was against this

background that IAPH and AAPA formed their respective Ad Hoc Dredging Task

Forces whose efforts over these past five years have been directed toward

achieving a more realistic and practical treatment of dredged material under

the London Dumping Convention.

ORGANIZING FOR SURVIVAL

The American Association of Port Authorities

In response to such ever-increasing problems of delays and escalating

costs and to continue efforts of those proposing more stringent, if not always

applicable, testing procedures, the American Association of Port Authorities

(AAPA) established an Ad Hoc Committee on Dredging in June 1979. (The Committee is now known as the Special Dredging Committee.) Its establishment was

recognition that the then existing AAPA Committee structures and ensuing ,."

resolutions were ineffective in moderating the trend toward increasing environmental restrictions of dredging activities. Early-on, goals were established.

These goals included the identification and documentation of those laws,

359
rules, regulations, agencies, procedures, and agreements which are creating

dredging problems. Targeted for study were concerns over mitigation, compensation, endangered species, bioassay test criteria, local costs, permit

delays, and interagency agreement. Additionally, the Committee was charged

with developing recommended revisions to existing regulations and procedures -,. ..

that would provide needed relief as well as the necessary documentation to

support those revisions. Finally, the new Committee was instructed to develop

a strategy to be used to achieve adoption and implementation of these revisions and to compile data on key legislators, committees, boards, and administrators to whom these revisions must be officially transmitted.

The International Associ- '-'

ation of Ports and Harbors

In early 1980, a similar committee to coordinate on the international

scene was established by the International Association of Ports and Harbors

(IAPH).

At the IAPH Executive Board Meeting in Brisbane, Australia, in April

1980, there was considerable discussion of the problems that the United

States' ports had been encountering in their attempts in recent years to dredge

their facilities. The Board recognized that those difficulties stemmed in a

large measure from the United States being party to the LDC. Further, the

Board agreed that it would be to the benefit of the IAPH membership to develop

a better understanding of port dredging practices and the relationship of

those practices to the terms of the London Dumping Convention.

The missions of the International Ad Hoc Dredging Committee are:

1. To review, report, advise, and submit recommendation on major matters

relating to seaport and inland port dredging and dredging equipment. .

2. To meet with and coordinate with the London Dumping Convention and

the Inter-Governmental Maritime Consultative Organization (IMO), the latter

being the organization designated to serve as the Secretariat to the LDC.

3. To develop a program on disposal of dredged material problem areas

for inland ports.

4. To publish an inventory of dredging equipment owned by dredging

companies worldwide, including a special section on new, innovative equipment.

5. To collect and publish information on state-of-the-art techniques.

6. To publisY an information brochure on sources of information and

assistance on dredging techniques and types of equipment best suited for given

situations.

MOVING TOWARDS THE INTENDED GOALS

These two committees, the Ad Hoc Dredging Committee of the IAPH and the :

Special Dredging Committee of the AAPA, have pushed forward in their effort to

resolve regulatory problems confronting the industry and to seek, as well,

360

" . '
The LDC does not specify particular standards and criteria that must be

applied in determining the "trace contaminants" and "rapidly rendered harmless" questions under Annex I. That is left, by and large, to the decisions

of national authorities. "Interim Guidelines" have been adopted to serve as

"guidance" for the interpretation and implementation of paragraphs 8 and 9 of

Annex I, but they establish no fixed standards. In the early years of the

Convention, the Contracting Parties appear to have construed the "trace

contaminant" pruvision of paragraph 9 as providing a categorical exclusion of

dredged material from Annex I. The original draft guidelines for the implementation of paragraphs 8 and 9 adopted at the Second Consultative Meeting in

1977 contained an exclusion for sewage sludge and dredged spoil. They were

endorsed in principle by Contracting Parties for further consideration as a

priority item. At the Third Consultative Meeting in 1978, Contracting Parties ..

adopted final Interim Guidelines. However, a substantial change was made.

Test procedures for determining "trace contaminants" were extended to dredged

material. This departed from the original understanding of the dredged material exclusion endorsed in principle by Contracting Parties the previous year.

This action at the Third Consultative Meeting created a serious dilemma

for many ports. As a result of growing industrialization and increases in

water-borne trade and commerce, many ports find that their harbor sediments

may contain substances listed in Annex I in varying degrees. This may present

special problems for those ports which rely upon ocean disposal of dredged

material for continued operation. The critical determinations are those

relating to the "trace contaminants" and "rapidly rendered harmless" questions. If an especially stringent standard is applied, it may trigger the

Annex I prohibitions and prevent ocean disposal of the dredged material--even

at the expense of continued port operations.

Concerns of this very nature began to arise shortly after adoption of the

Interim Guidelines at the Third Consultative Meeting. In 1979, environmental

groups in the United States insisted that Annex I barred the ocean disposal of

dredged material at the Port of New York-New Jersey and at the Port of Lake

Charles, Louisiana, because the dredged material allegedly contained Annex I

substances that exceeded "trace contaminant" levels. It was against this

background that IAPH and AAPA formed their respective Ad Hoc Dredging Task

Forces whose efforts over these past five years have been directed toward

achieving a more realistic and practical treatment of dredged material under

the London Dumping Convention.

ORGANIZING FOR SURVIVAL

The American Association of Port Authorities

In response to such ever-increasing problems of delays and escalating

costs and to continue efforts of those proposing more stringent, if not always

applicable, testing procedures, the American Association of Port Authorities

(AAPA) established an Ad Hoc Committee on Dredging in June 1979. (The Committee is now known as the Special Dredging Committee.) Its establishment was .-

recognition that the then existing AAPA Committee structures and ensuing

resolutions were ineffective in moderating the trend toward increasing environmental restrictions of dredging activities. Early-on, goals were established.

These goals included the identification and documentation of those laws,

359

* --,.:.:.~:.;.---&<..o -. . . . . -. . --. 
rules, regulations, agencies, procedures, and agreements which are creating°

dredging problems. Targeted for study were concerns over mitigation, compensation, endangered species, bioassay test criteria, local costs, permit

delays, and interagency agreement. Additionally, the Committee was charged

with developing recommended revisions to existing regulations and procedures

that would provide needed relief as well as the necessary documentation to

support those revisions. Finally, the new Committee was instructed to develop

a strategy to be used to achieve adoption and implementation of these revisions and to compile data on key legislators, committees, boards, and administrators to whom these revisions must be officially transmitted.

The International Association of Ports and Harbors

In early 1980, a similar committee to coordinate on the international

scene was established by the International Association of Ports and Harbors

(IAPH).

At the IAPH Executive Board Meeting in Brisbane, Australia, in April

1980, there was considerable discussion of the problems that the United

States' ports had been encountering in their attempts in recent years to dredge

their facilities. The Board recognized that those difficulties stemmed in a

large measure from the United States being party to the LDC. Further, the

Board agreed that it would be to the benefit of the IAPH membership to develop

a better understanding of port dredging practices and the relationship of

those practices to the terms of the London Dumping Convention.

The missions of the International Ad Hoc Dredging Committee are:

1. To review, report, advise, and submit recommendation on major matters

relating to seaport and inland port dredging and dredging equipment.

2. To meet with and coordinate with the London Dumping Convention and

the Inter-Governmental Maritime Consultative Organization (IMO), the latter

being the organization designated to serve as the Secretariat to the LDC.

3. To develop a program on disposal of dredged material problem areas

for inland ports.

4. To publish an inventory of dredging equipment owned by dredging

companies worldwide, including a special section on new, innovative equipment.

5. To collect and publish information on state-of-the-art techniques.

6. To publish an information brochure on sources of information and

assistance on dredging techniques and types of equipment best suited for given

situations.

MOVING TOWARDS THE INTENDED GOALS

These two committees, the Ad Hoc Dredging Committee of the IAPH and the

Special Dredging Committee of the AAPA, have pushed forward in their effort to

resolve regulatory problems confronting the industry and to seek, as well,

360

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- - * " f *.. - ft.-._' *. f.. t*. . ' . - , .-- -,_ _- - - . - - - .- - - .

solutions that are environmentally and economically sound. The following is a

brief chronology of IAPH/AAPA efforts in seeking to achieve a more realistic

and meaningful treatment of dredged material under the LDC.

1. In the fall of 1979--shortly after the Annex I prohibitions were

asserted for the first time to halt essential port operations in the United

States--AAPA sought and obtained representation on the EPA-chaired U.S. Ocean

Dumping Advisory Committee, which is responsible for formulating U.S. positions under the LDC. It was the hope of AAPA to be able to influence U.S.

positions to ensure that they would have proper regard for port concerns.

AAPA also requested a place on the U.S. delegation to the Fourth Consultative

Meeting of the LDC later that year, but was refused--even though a representative of a major environmental group adverse to ocean dumping of dredged mate- *

rial was included on the delegation.

2. In 1980 IAPH made use, for the first time, of its "observer" status

under the LDC to attend the Fifth Consultative Meeting of Contracting Parties. '.

In its initial attendance at the meeting, IAPH emphasized the drastic effect

upon port operations that could occur if Annex I were applied to halt needed

dredged material disposal. IAPH also suggested the possibility of using certain "special care" techniques (such as clean material capping) for the ocean ,t

disposal of highly polluted dredged material. The IAPH submission was well

received, and IAPH was asked to make a more detailed presentation at the next

- meeting of the Scientific Group.

3. In May of 1981, IAPH attended the Scientific Group meeting in

Hailfax, Nova Scotia, and presented a detailed paper on the use of "special

care" measures. This focused scientific attention upon these techniques and

has resulted in their growing study and use since that time.

4. In October 1981, IAPH attended the Sixth Consultative Meeting in .-.

London. IAPH reported upon additional experience with "special care" tech- ,. ."--

niques and also suggested that the "emergency" provisions of the LDC should

apply when a port had no alternative means of disposing of polluted dredged

material other than dumping at sea. Although this construction of the

"emergency" provisions was not approved, Contracting Parties did express the

view that such situations might appropriately be handled through the use of.

"special care" measures.

5. In September 1982, IAPH attended the meeting of the Scientific Group

in Paris, France. The Paris meeting was one of extreme significance. In

addition to the IAPH submission on "special care," great interest was

expressed in developing additional "criteria" for classifying substances to

Annexes I & II, with emphasis upon the use of numerical standards. This

renewed consideration of the basis for "classification" presented a major

opportunity for IAPH to make a new case for a separate treatment of dredged

material. IAPH seized this opportunity and offered to prepare a scientific

paper addressing the special features of dredged material in the context of

classification criteria.

6. In February of 1983, IAPH attended the Seventh Consultative Meeting

in London. In addition to presenting port positions on the use of "special

care" techniques and on the preparation of the proposed paper for the development of "classification criteria," deep concern was expressed over a proposal

361 -'-ft=..

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by two small Pacific islands, Kiribati and Naura, to ban all disposal of

radioactive material in the oceans in terms so sweeping that it could be

construed to apply to naturally occurring radioactive isotopes which are present in all harbor sediments. Other nations concurred in the IAPH concerns,

and no binding action on the radioactivity issue was taken at the Seventh

Consultative meeting.

7. At the Seventh Meeting of the Scientific Group in October 1983, in

London, IAPH submitted two technical papers relating to dredged material. The

first was entitled "A Special Report on Application of Classification Criteria

to Dredged Material with Emphasis Upon Petroleum Hydrocarbons and with Additional Consideration of Lead in Dredged Material." In it, IAPH described the

unique characteristics of marine sediments that serve to tightly "bind" and

"hold" Annex I substances so that they are essentially "unavailable" to the

marine biota when disposed at sea. IAPH demonstrated that these recognized

mitigative features allowed the disposal of dredged material containing

Annex I substances without significant risk to the marine environment. In the

second paper--entitled "An Updating of Special Care Measures for Disposal of

Polluted Dredge Material in the Marine Environment"--IAPH focused upon the use .

of a particular "special care" measure, "clean material capping." IAPH

reported upon its effectiveness in reducing the disposal of contaminated

dredged material to a low risk status. The Scientific Group agreed that an

interim evaluation had shown that "capping" is technically and scientifically

feasible and is a useful mitigative measure that shows promise as a long-term

management strategy for the ocean disposal of contaminated dredged material.

8. In December of 1983, IAPH attended a meeting of the Ad Hoc Group of

Legal Experts that was convened to consider legal issues relating to proposals

for the sub-seabed disposal of high level radioactive wastes. At this highly

emotional meeting, the Nordic countries introduced a resolution to ban all

seabed disposal of high level radioactive wastes and all other wastes listed

*" in Annex I as well. Because of analogies that had been drawn between "capping" -' and "seabed disposal," this presented a direct threat to the continued use of

capping as a means of disposing contaminated dredged material at sea. IAPH

expressed its strong opposition to the Nordic resolution and the need to

exclude dredged material from its terms.

9. At the Eighth Consultative Meeting in February 1984, IAPH presented a

major new recommendation. Based upon the conclusions reached in its classification criteria paper, IAPH expressed the view that dredged material containing Annex I substances should not be subject to the strict prohibitions of

Annex I but should be regulated under the "special permit" provisions of

Annex II. IAPH examined the dramatic advances in scientific knowledge of

dredged material since the original drafting of the Convention in 1972 and

emphasized the unique properties of marine sediments that mitigate the effects

of Annex I substances. The meeting took note of the IAPH presentation and - agreed that the IAPH recommendations should be considered by an intersessional

working group that was established to continue the development of criteria for

the classification, addition, and deletion of substances to the Annexes.

The Eighth Meeting also took note of the findings of the Scientific Group

that an interim evaluation of "capping" had demonstrated that it is a feasible

and ef' ctive technique and members endorsed the continuing use of "capping"

on a reoearch basis. IAPH also expressed its support for the view expressed

362

...................... "........"." ............. "-"....'..,.-..... .. " Z ¢ '_t ' . _ u.'¢'_, ''_' '_.',. '_' ' . . . . . . . . . . . .
by the French delegation that many of the Annex III guidelines (which include

factors to be considered in granting general and special permits) cannot be

applied to dredged material, which properly requires separate guidelines.

IAPH expressed its support for this proposal and offered, subject to receiving

authorization and funding from its sources, to assist in such work. Finally,

IAPH renewed its objection to the Nordic resolution (which was re-introduced)

that proposed an absolute ban on seabed disposal of high level radioactive

wastes and all "other wastes" listed in Annex I. IAPH achieved a major success in having the language relating to "other wastes" deleted from the

resolution. Dredged material was thereby excluded from the intense debate

regarding the sub-seabed disposal of high level radioactive wastes.

A CALL FOR EVALUATION--THE ISSUES UNDER SCRUTINY

We are determined and are currently continuing our productive and timely

efforts to achieve our goals. In the dozen or so years that have passed since

the drafting of the Convention, Contracting Parties have ccItinued to express

an interest in reviewing and evaluating the bases for the several criteria

originally devised for allocating substances to Annexes I and II. Thus, with

new member nations involved in plenary deliberations, Contracting Parties wish

now to be assured that the extant criteria are technically sound and compat- __

ible with current knowledge. Hence, they have called for a penetrating review

of the existing criteria. They wish to receive also from the Scientific Group

recommendations as to appropriate additions to the criteria if and when new

knowledge or concepts justify such additions. Responsibility for conducting

the formal study of these issues has been assigned to a select working group

that will report its findings to the Scientific Group for definitive discussion at its meeting in February 1985.

As requested at the Eighth Consultative Meeting and in preparation for

the July 1985 Scientific Group meeting, the Ad Hoc Expert Group on the concepts and purpose underlying the annexes to the LDC met in London in July

1984. Thirteen international scientists were in attendance, including

Dr. Willis E. Pequegnat, world renown oceanographer assisting IMO as a

technical consultant. The purpose of that meeting was to review current

papers addressing the issues of classification, addition, and deletion of

substances to the Convention's Annexes and provide the basis by which to

establish the direction and objectives of the proposed paper requested by the

* Contracting Parties.

This new document, "Some Suggested New Annex Allocation Criteria of LDC

Related to the Toxicant Binding Properties of Dredged Material," has been prepared by Dr. Pequegnat, and is currently undergoing review prior to its official release at that March 1985 IAPH Scientific Group Meeting. The paper

attempts to respond substantively to both requests of the Contracting Parties,

i.e., to evaluate present criteria and delineate additional criteria or, at

the very least, suggest how those already under consideration should be

employed. Four very different but interrelated issues are dealt with, to wit:

1. Evaluation of the present list of substances in the Annexes (does not

deal with radioactive materials or with persistent plastics).

2. Evaluation of the present three allocation criteria.

363

. - . ° 

o • ~~~~** . =.... ... .' ....... ... ...-.-... ....... .... . .. •...-= ° ...
I - .

3. Justification tor adding particular new allocation criteria to the

present list.

4. Establishing the relationship of the provisions of the Annex III

• guidelines to the above three considerations.

Although the four issues stated above constitute implicit objectives of

this study, it is appropriate to be explicit as to the topics which received

most emphasis. There is a strong conviction that it is not scientifically

sound to expect that criteria for allocation of substances to the Annexes can

be made to apply in an equal manner to a given toxicant when it is disposed

into the ocean in different forms of carriers. This point is recognized in

Annex III and should be given careful consideration when one is required to

hand down a regulatory decision from the provisions of Annex I. When chemical

form is linked with the concept of bioavailability, we achieve a rational

solution to the nagging problem of how to make full use of the ocean's capabilities and still protect its living resources and prevent hazards to human

health. To achieve this goal, Dr. Pequegnat examined:

1. The concept of toxicant bioavailability and demonstrated how its

* magnitude is dependent in part upon the geochemical properties of the carrier

or milieu in which it is measured. Here the emphasis is upon certain types of

*" marine sediments. .

2. In considerable detail some of the geochemical properties of the

above marine sediments that account for their ability under certain conditions

to provide the first line of defense against the harmful effects that Annex I

toxicants would otherwise have upon marine life.

3. Explained in reasonably understandable terms the functional (physiological) mechanisms that permit marine life to erect a second line of defense

by detoxifying or otherwise reducing the hazards of absorbed organic and

inorganic toxicants.

4. Why the concept of biopersistence may be more realistic than environmental persistence as it relates to toxicity and the food chain.

5. How these geochemical properties of the carrier can modify the regulatory application of the terms toxicity and bioaccumulation, recognizing that

pharmacological toxicity may be absolute but ecological toxicity is relative.

SUMMARY OF STUDY'S FINDINGS

"Some Suggested New Annex Allocation Criteria of LDC Related to the Toxicant Binding Properties of Dredged Materials" is an ambitious study with landmark implications. The major conclusion drawn from Dr. Pequegnat's study

indicates that in many instances the disposal of toxic dredged waste into the

ocean should be the preferred alternative over any reasonable type of upland

disposal. This conclusion is in conflict with related international policy

proposals currently being considered and discussed by the LDC. Specific findings of that study which support this conclusion are as follows:

364

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7~~ - U-7 L W. , .

1. It is not scientifically or pragmatically sound to expect that a

criterion for allocation of substances to the Annexes should routinely apply

in an equal manner to a given toxicant when it is disposed into the ocean as a

component of different wastes. Unfortunately, the point is valid that the

Convention fails to make a definitive separation between substances and

wastes, either in Article IV or the Annexes. Yet this is a critical issue to

some governmental and industrial groups.

2. A waste per the Convention must be defined as the toxicant or toxicants of concern (e.g. an organochlorine) and the "carrier" (sewage sludge, s--,

dredged waste, etc.) in which it is disposed. Thus, carrier plus substances

listed in the Annexes comprise "the waste." As we shall see, then, it is the

waste, the ecological entity, that must be tested for potential impacts.

3. Thus, the nature of the carrier plus the chemical species involved

generally determine whether or not a toxicant will be available to the biota.

Therefore, bioavailability and physicochemical form of the carrier are perhaps

the two most important considerations in dealing with disposal criteria. In

general the carrier determines availability. So if a toxicant is not bioavailable, the other criteria should not apply.

4. Marine sediments, especially of estuarine origin, characteristically

contain clay minerals, such as montmorillonite and vermiculite, humic acids,

and sulfides, all of which are effective at reducing the availability of toxic

metals or synthetic organic compounds to the biota.

5. When because of the composition of the carrier a substance does not

have bioavailability, there can be no absorption into the organisms' tissues.

This physicochemical suite of carrier properties comprises the "first line

of defense" against environmental impacts.

6. Given that a toxicant is not bioavailable to marine plants or

metazoan animals, it follows that attempts to apply the extent three criteria

(toxicity, bioaccumulation, and persistence) are misguided and confusing.

Realistically the waste has satisfied the intent of paragraphs 8 and 9 of

Annex I.

7. Even when trace amounts (or more) of a toxicant in a waste are bioavailable and have actually been absorbed they will evoke the second line of

defense, which is physiological. This defense mechanism protects the metabo- 7

lic enzyme centers (ENZ). These enzymes control all of the cellular functions.

8. When toxic metals are absorbed, they are tied up by sulfur-bearing,

low molecular weight proteins called metallothioneins, which are synthesized

by liver and kidney cells. So long as the Metallothionein Pool (MT) is not

overloaded, the ENZ pool is protected. Evidence thus far researched indicates

that only a small percentage of the metallothionein proteins are tied up in

natural populations of marine animals, even in polluted regions.

9. In similar manner, organic toxicants are bound in one or both of two

places. If they are soluble in lipids (e.g. PCBs), some are stored in fat

tissues, production of which appears to be stimulated by the uptake of these

organics as well as by some metals like cadmium. Synthetics are also

365

........................................................... .. ..-. •
sequestered by the glutathione pool. Both of these mechanisms are also part

of the second line of defense. In addition, it must be pointed out that

organisms can break down (metabolize) some toxicants. Frequently, however, in

the case of synthetic organics, the metabolities may be more toxic than the

"' parent compound (e.g. DDE from DDT).

10. It is for the above reasons that investigators have rarely observed

serious 

in polluted 

impacts 

sediments 

upon the 

containing 

marine biota, 

Annex 

especially 

I toxicants. 

the 

The 

benthic 

few exceptions 

component, 

are

even L

acute cases where the loading of toxicant into the environment was not only

massive but also occurred in a short interval of time.

11. Clay minerals micelles like those of montmorillonite and vermiculite

have huge external and internal surface areas (800 or more square meters per

one gram dry weight of material) available for binding toxication of metals.

Other binding agents are sulfide and hydrous oxides, and particularly humus.

12. Humus micelles are also efficient binders of various toxicants, ..

particularly the synthetic organic compounds.

13. Dredged materials that carry significant loads of toxicants will

more frequently than not possess substantial percentages of clay minerals,

humic acids, and other sequestering agents. Moreover, this binding capability

of the material is measurable.

14. It is proposed that when a dredged material, as carrier, contains

toxic substances, that is, when the "waste" has in it Annex I toxicants,

effectively bound by the above agents as evidenced by predetermined percentages of clay minerals, humics, etc., it should be considered a "naturally

acceptable waste" that is eligible for ocean disposal under the permit and

care procedure of Annex II.

15. It is even possible that wastes containing Annex I substances and

deemed unacceptable as they are for safe ocean disposal can be upgraded for

such disposal by the addition of calculated amounts of effective sequestering

agents, depending upon the particular toxicants involved.

IN CONCLUSION...

These IAPH/AAPA efforts have been undertaken against a history of port

*. "uninvolvement" in ocean dumping matters. They have come at a time when pres-

. sure for stricter environmental controls has not abated, but remains on the

.* increase. These problems are still not yet finally settled. New issues are

constantly emerging. One need only look at the Agenda of next year's Scientific Group meeting in London, and at the Agenda of the 9th Consultative Meeting

next year to appreciate how much consideration is being given to matters that

affect port interests. These include continued evaluation of "special care"

measures mentioned (along with the attendant legal questions that have been

raised as to their routine use), further inquiry into "trace contaminant"

levels, further development of new classification criteria, consideration of

the transfer of new substances (such as lead) to Annex I, and the question of

radioactive waste disposal. Decisions will hopefully be made upon these

issues within the next year. On the domestic front, efforts are continuing to

include greater environmental restrictions upon dredged material in the MPRSA;

366
- and the EPA is still planning to pubjish a proposed revision to its ocean

- dumping criteria--the first revision since the environmental changes adopted

in 1977.

In the midst of this legal and regulatory activity, what is significant

is that this time ports are not absent. They are not uninvolved. Port views

are being expressed. The port voice is being heard. The challenge is here.

It cannot be avoided.

b We have been most appreciative of Dr. Sato's support from IAPH Head-

* quarters in Tokyo and know that we can also count on the Japanese government's

and ports' support on these vital issues when they are debated at IMO in

London.

367

, . . . . . . . ..-...- .*-*. ** ,~ 
PROGRESSIVE TRENCHING USING A SCRAPER DIGGER

T. Inoue

Japan Sediments Management

Association

ABSTRACT

The progressive trenching method developed in the

United States was introduced by Mr. Calhoun in this

meeting. After his presentation the interest in it.*.

rose in our country. In the management of a disposal

area in Tsu-Matsuzaka Harbor the progressive trenching

method was first applied in our country to promote the

dewatering of dredged material. In this case the..

digging of the trench was performed by a floating

scraper. This paper reports how progressive trenching " " - "

using a scraper digger was carried out in Japan.

BACKGROUND OF MANAGEMENT

In order to restore the estuaries of Shitomo River the sediment was

removed in 1980-1982 (Figure 1). The removed quantity of sediment was

Difosalj~ Disposal :eodorization

Dredge

Shitomo River

.. ~~~~~. . .. .... ..

Figure 1. Dredging at Shitomo River estuaries

368
322,200 m3 and its removal depth averaged 4 m. The dredged material was

transported hydraulically to a spill water treatment pond through a deodorization plant. At the disposal area the progressive trenching method was

applied using a scraper digger to promote dewatering of the dredged material.

SCRAPER DIGGER

In the application of the trenching method, the most important factor is

how to dig the trenches. In a large disposal area a regular trenching machine -.5"

may be used (Figure 2). However, in our case, because of the small-scale

disposals, it was necessary to contrive a cheaper trenching method. From this

requirement, a floating scraper digger was devised. The scraper is shaped

like a boat with its head bow-shaped to reduce soil resistance while advanc- . . ,

ing. The weight is controlled by ballast according to the required trench

depth, considering the buoyancy acting on the float and contact pressure of

the surface. Figure 3 shows the appearance of the scrapper.

-i X I II : 1-1

3000

View _Side 

0900

Elevation

Plan

Unit: rmm

Figure 2. Scraper digger

369

- - - - - - -~ ***~**- a-.
Jb46

. %

Figure 3. Appearance of scraper

The bottom is made of a 30-cm plate to obtain a good finished cut. The

scraper is equipped with wings at both sides for stability. Trench excavation

is conducted such that two crawler cranes standing on facing banks draw the

scraper digger in succession (Figure 4).

Crawler Crane

Figure 4. Excavation of trenches

TRENCHING WORK

The basic concept of progressive trenching is described by Mr. Calhoun in

his paper. Therefore, it need not be repeated here, but it is depicted

diagrammatically in Figure 5.

The inside wails of the pond were covered by vinyl sheets (4 mm) to prevent water permeation from dredged material to the surrounding area. Therefore, water contained in the dredged material had to be dewatered or solidified by solidificants. Moreover, since the project was conducted during the

370

- , -%7
0° ~*St -oa

STrench

i~

'Material*•, ' • •"

Evaporation Crc

Draining Pit

Figure 5. Principle of dewatering by trenches

winter, with its short days and low temperatures, desiccation by sunshine was

difficult. Because of these circumstances, the progressive trenching method

was adopted to accelerate the dewatering of dredged material.

The trenches were divided into mains and branches (Figure 6). Main tunnels were excavated by a clamshell, and braiiches by a scraper digger. Total

* length of the main trenches was 1,027 m and the branches was 4,444 m. The

* pitch of the branch trenches was 50 m. The excavation of trenches was con- -

ducted five times progressively over an interval of about 25 days.

The area of the filled land was 76,000 m2 and the quantity of the filled

material was 220,000 mn3 . Dividing the filled area into five divisions the

trenching work was conducted in order from V1to V 5 (Figure 7). The trench -.

sections excavated are shown in Figure 8. Figure 9 shows a photograph of an

area being worked by a scraper digger.

371

. . . .*:-.j.:,-.
W .ZV : T '. I Z7r I 1 .'. ... -.- . -.- '.~JY.rp.

50m

Main~~~~r. TrnhsBanhTece

Effluent

Fiue Main renches an branch Tees

Effluen

V,,

Figure 7. Disposal area divided into five divisions

372
P.~~~~~ ~ 1--7 ~ ~~ WI..RTPzP zMV 1

1st Trenching Original

(66 days after the Sediment 1.600

end of filling)Sufc I

2nd Trenching ZA

(99 days)

350

1.000 -

2.500 

- 7

3rd Trenching

(124 days) !

1.000 -

4th Trenching

(136 days)

Original

2,800 Sediment

5th Trenching

(163 days)

Figure 8. Trench sections (in millimeters)

373

* . . .. S. * . .. . ., .*... .*ty~y.< . . *,. -ore
I IM

Figure 9. An area being worked by a scraper digger

The depth of each trench was 250 -m after the first trenching and 800 -m

after the last one. The area of excavated sections changed from 3,250 c~m 2 to

15,600 cm.

RESULTS

Water content 30 cm below the surface was 400% at the end of filling and

261% just prior to the first trenching (Figure 10). Water content decreased

* gradually as trenching advanced:

1st Trenching (66 days) 261%

2nd Trenching (99 days) 211%

3rd Trenching (124 days) 188%

4th Trenching (136 days) 185%

5th Trenching (163 days) 180%

The water content after 185 days was 149%. Consequently, as the result

of trenching, a reduction in water content of 43% 21 was attained.

Water content at a point 30 m away from a trench was approximately equal to

the water content at a point near the trench in shallow trenching. However,

as the depth of the trench progressed, the water content became lower at the

* point near the trench and increased proportionally with distance.

*Figure 11 compares water content with distances from the 4th and 5th

trench. This distribution indicates that the water content in the disposal

- area begins to drop at points adjacent to the trench and gradually extends to

* distant areas. Figure 12 shows the crack generation on the surface. The

settlement measured is shown In Figure 13. Settlement after 185 days in

- 18 cm. The mean settling rate is about 0.15 cm/day.

374 . ,°

- j C . tt* ~ . l r - J .t ' , . .. ,- 
: .. " ...... . ...

900 LJ -i

00 Trench Depth ,

600 (CM)

400"

149 -'-"..-

2 3 4 5 Trench No.

66 99 124 136 163 185

Days after Trenching

Figure 10. Change in water content

Figure 14 shows the results of cone penetration tests. The cone penetration stress was 0.25 kg/cm2 at the beginning and increased to 0.66 kg/cm2 by

the 5th trenching and finally to 0.9 kg/cm2 . This means that in this case the

filled area has stabilized well.

COVERING WORK

On the surface of dewatered dredged material permeable sheets were

stretched and then foreign soil 1 m thick was placed on top of the sheets.

The sheets used had a good permeability and a tensile strength of over

100 kg/5 cm2 as determined by the Japanese Standards Association test methods

(Figures 15 and 16). (See Appendix A for test methods.)

When the covering work has to be finished quickly, it should be

remembered that the thicker covers take longer to apply. In such cases an

unequal settlement sometimes occurs due to the ubiquitous load of the soil.

To avoid such an unexpected risk, a method of sheet stretching was adopted.

The thickness of the soil cover was 30 cm for the first layer and 20 cm for

the second, and 50 cm for the final layer, a total of 1 m. For transporting

and spreading the soil a small dump car with eight wheels and a 1-ms capacity

was used. For covering the second layer a small bulldozer of 3-ton capacity

was used. For the final layer an l -ton bulldozer was used for soil

spredding.

To prevent whirling up of sandy dust, grass was planted on the ground.

375

.- * . -.- ,-. . ..- ... . ' * '=.. . '"" . .*** , - . "*'' .. % -..-''-.%- . " -* .,. * .-. ".'.. .. '.'*.. .. ..... .'...' '"". . . '" -''-. . . . '... ,'...'- '- . - " ' % '' ' '''

* * ~ .. i
4 t

20

S150

0

10 20 30

Distance f rom Trench (in)

Figure 11. Water content near the trench

SO ..

Figure 12. Cracks on the surface

376

% A
12 3 4 5 Tec

66 99 124 136 13 185 Days

5

Cn 15.

20-

25

Figure 13. Settlement by trenching

1.0-

Q93

0.7J

0o6 0.66

05

Cn Q46 0.4

S0.3

S02- 0.25

~'0.1-

0 UTrench No. 1 2 3 4 5 66 99 124 136 163 165

'Days After Trenching

Figure 1.4. Cone penetration test results

3777
-

Covered area 69,210 m3

Sheet strength 100 kg/5 cm2

Figue seet 15 Diaratreth

Figure 1. Diagra of sheet stretching

378
CONCLUSIONS

This project was the first instance of the progressive trenching method

by a scraper digger attempted in our country. The main attribute of this

method is that no expensive trenching machine is required. Therefore, it can

be used economically for any small-scale landfill. . ' ".

Although some room for improvement remains, the acceptability of the new

method for practical use was verified by this study.

APPENDIX A: TEST METHODS

The test methods for tensile strength of fabric are standardized as follows by the Japanese Standards Association in our country. For heavy fabric,

if the fabric is subject to raveling, the test specimen is prepared by retaining four or more yarns at both edges outside the test width (3 cm) and then

cutting the yarns 5 cm from the ends of clamping jaws, as shown in Figure Al.

unit; cm

Approx. 30

2 20 2

_EE 4lro

When testing tensile strength, the sheets have a

strengthh of over 00 kg/5 cm.

Figure Al.

When testing tensile strength, the sheets have a strength of over 100 kg/5 cm.

379

L5,

. .......
ENVIRONMENTAL CONSERVATION IN THE PORT OF MAIZURU

T. Matsuoka

Civil Engineering and Construction Department

Kyoto Prefectural Government

INTRODUCTION

The Port of Maizuru, located in the central part of the Japan Sea coast

of the Main Island, is a natural port blessed with good geographical conditions. Maizuru Bay is narrow at the mouth and runs deep and wide into the

inland in two directions forming two separate bays called Nishiko (the west

port) and Higashiko (the east port). The name of the region, "Maizuru," is

said to have originated from the geographical shape, which resembles a crane

with its wings spread.

Maizuru City is the key city in the northern part of Kyoto Prefecture

with a population of 98,000. With the current economic growth and increased

* contact with neighboring countries across the Japan Sea and other foreign

countries, Maizuru City is becoming a developed area. In this area a high

* priority is attached to the improvement of the port as well as to the develop-

* ment of a brisk, affluent, and peaceful industrial port city where life is

* comfortable.

Higashiko Bay was first developed as a naval port with the construction

* of a naval station there in 1901, while Nishiko had developed as an important

* trading port on the Japan Sea coast, primarily for trade with neighboring

countries, since a pier for large-sized ships was constructed in 1913. By the

end of the Taisho Era (1912 - 1926), regular services between Maizuru and the

Ports of Vladivostok, Chongjin, and Talien were launched successively, and

* Nishiko thrived on trades with neighboring countries (Figure 1).

At the end of World War II, with the closure of the naval port, both

Nishiko and Higashiko were redesigned to be commercial ports, and the Port of

Maizuru was designated to be one of Japan's major ports in 1951.

In the 1960's, following the inauguration of the Hokkaid, Regular Service

Line and the designation as a port-of-call for the Japan-U.S.S.R. Regular Service Liners, domestic and foreign service lines have been launched. The completion of Pier No. 3 and Pier No. 4 was followed by a marked increase in

cargo volume handled in this port (Figure 2).

The Port of Maizuru is particularly important as one of the active ports

handling timber in this country. However, due to the current stagnant activities in the wood business, the volume of timber handled this is on the

decline.

380

-...
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Figure 1. Geographical relation of the Part of Maizuru with neighboring ports ti

381
414

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3829
t . -- - .4" . - T ~* 

IMPROVEMENT OF THE PORT OF MAIZURU

The port of Maizuru has diversified functions including fishery, Maritime

Self-Defense Force, and marine recreation. It is, therefore, necessary to

have a port improvement plan based oa a long-term view. In 1976, the port

improvement plan underwent an overall change where Nishiko was designed to be

a commercial port for external trade with neighboring countries, while

Higashiko was designed to be a commercial port for the domestic trade as well

as a port for ferry boats between Malzuru and Otaru currently using Pier No. 2

in Nishiko.

According to the Sixth Five Year Plan for Port Improvement, the extension

and redevelopment of Pier No. 2 and the construction of a pier in the Maeshima

District are now under way along with the construction of the Maizuru Route of

the Kinki National Highway. In this way, the port improvement plan is being

steadily developed with the aim of making this port the key port for distribution of goods in the northern Kinki District as well as a port for international trade (Figure 3).

RATIO OF WOOD TO THE TOTAL CARGO VOLUME

HANDLED IN THE PORT OF MAIZURU

In 1958 the Port of Maizuru began handling mainly northern wood from

U.S.S.R. The volume of timber handled steadily increased each year from the

initial volume of 14,068 tons to the peak volume reached in 1970 of

1,233,262 tons. After 1970 business activity in the domestic wood market

slackened, and the volume of wood handling kept decreasing at a moderate pace.

It has slightly picked up since 1982 (Table 1).

The data in the past 10 years show that wood accounted for 28.2% (79.0%

of the total import volume) of the total cargo volume handled there in 1974,

and 19.5% (92%) in 1983, a drop of approximately 9%. Meanwhile, the ratio of

wood to the total import volume increased by 13% over these 10 years, indicating that the drop in the total import volume surpassed that of the total

volume of wood handled (Table 2).

LOADING AND UNLOADINC OF WOOD ON THE SEA SURFACE

AND ENVIRONMENTAL CONSERVATION .'...

As mentioned, the Port of Maizuru has been handling mainly northern wood

from U.S.S.R. since 1958. However, because of a lack of exclusive berths and

dolphins for wood, timber was unloaded onto the sea surface (wood was discharged to the sea surface and carried in floats to timber ponds). This led

to a massive deposition of sinking wood, bark, and wire on the sea bottom,

L which degraded the seawater environment in the bay and caused serious adverse

effects upon the fishery. _

To cope with this situation, the Kyoto Prefectural Government laid down

"The Outline for Wood Handling" in 1969, followed by the organization in 1972

of "The Port of Maizuru Wood Pollution Prevention Committee" consisting of

longshoremen and wood processors. A clean-up of sinking wood and bark on the

sea bottom has been conducted since 1974, primarily by the polluter assisted

by Kyoto Prefecture and Maizuru City. Table 3 shows the volume of wood

handled on the sea surface and the cleaning operations of the sea bnttom.

383

.:- -..

A..---....
4N, * ? -::.

-Y.

F e rM iRon the hih y wor ea t

s Io, -wwhr ,, . .:.? -

Port ofo'.izor

cleaning ThePort operatBons of Maizur,, by consigning Wood Pollution the work Prevention to the Maizuru Committee Fishery promotes Cooperative. the

twice a year, in summer and in winter. Special nets for cleaning such s

trawl nets are employed to sweep the sinking wood, bark, and wire from the sea ,... botTto.

In addition to these operations, the Kyoto Prefectural Government (the.-'- ",.

" ~port management body) constructed a cleaning boat, "Sokaku Maru" (with a -"" ,4 ~cleaning capacity of 12 m3 /day, 8-ton gross) and an incinerator (Table 4) with':.:2:

the daily capacity of 7.5 tons/day. Management of both was assigned to _

Maizuru City. Maizuru .City then consigned the actual operation of this

3841

Out's -..

Osaka Ba

Figure~~~~~~~ ~ mrvmeti., ~ ~ ~ ~ ~ iha 3'.. Prgeso etoklaigt h

• ~ ~ ~ ~ .. ~ . .. ~Pr Ma.. i....-.. z-. ur-u . . ... .. .. .',.j ,.._. :-'-

iTh .Port..' .."n of .. .t........... Wo'o-d Poluio Prvnto Commtte .... prmoe .
TABLE 1. CHANGE IN THE VOLUME OF IMPORTED WOOD HANDLED AT

THE PORT OF MAIZURU

Wood of Wood of

Northern Origin American Wood Southern Origin Total

No. Volume No. Volume No. Volume No. Volume .. ,

of Wood of Wood of Wood of Wood of Wood of Wood of Wood of Wood e,

Year Carriers tons Carrier tons Carriers tons Carriers tons

1958 4 14,068 .... .... 4 14,068

1959 15 46,001 .... .... 15 46,001

1960 19 53,044 -- -- 8 9,965 27 63,009

1961 21 64,336 8 32,959 12 17,804 41 11,099 .. '

1962 47 167,283 14 58,740 12 20,538 73 246,561

1963 59 222,964 8 25,298 12 19,137 79 267,399

1964 78 309,245 15 37,484 15 22,557 108 369,286 -

1965 76 318,567 15 34,596 24 38,533 115 391,696

1966 87 378,517 18 60,239 18 37,414 123 476,170 -. '-

1967 116 524,022 31 115,809 28 80,149 1/5 719,980

1968 128 534,310 38 153,615 69 193,447 235 883,372

1969 147 568,708 29 109,509 84 232,110 260 910,327

1970 201 804,886 46 185,277 78 243,099 325 1,233,262

1971 203 798,433 29 147,646 61 196,666 293 1,142,745

1972 217 796,959 34 186,088 70 222,905 321 1,206,952

1973 240 844,716 38 160,266 66 224,732 344 1,229,414

1974 178 615,749 31 157,732 59 232,396 268 1,005,877-.

1975 165 617,805 29 142,367 40 154,920 234 915,092

1976 157 616,401 28 186,355 50 173,792 235 976,548

1977 166 710,199 36 218,382 62 210,660 264 1,139,241

1978 158 632,151 25 144,128 63 210,350 246 986,629

1979 157 600,314 43 179,656 82 238,397 282 1,018,867 -

1980 134 501,422 39 164,489 66 221,512 239 887,423

1981 121 442,633 22 88,384 47 138,947 190 669,964 "

1982 137 506,762 21 96,310 38 158,014 196 761,086

1983 161 582,394 19 72,603 30 127,208 210 782,205

Note: The Port of Maizuru began importing foreign wood in 1958.

385

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387
TABLE 4. OPERATION OF THE BARK INCINERATOR

Recovery Site* Volume of Bark

On Shore On the Sea Incinerated

Year m3 m3 m3

1981 

IU

4,981 1,043 6,024

1982 5,445 1,219 6,664

1983 4,966 1,141 6,107

On shore bark recovered at wharves.

On the sea - floating bark recovered by the cleaning boat "Sokaku Maru."

equipment to the Port of Maizuru Wood Pollution Prevention Committee to carry ..'

out cleaning and incinerating of sinking wood and bark produced during daily

loading and unloading work on the sea surface.

Two thirds of the expenditure necessary for these operations is

shouldered by the polluter, the Port of Maizuru Wood Pollution Prevention

Committee.

NOXIOUS MATERIALS RELEASED FROM SINKING WOOD AND BARK I'

To assess the effectiveness of the current cleaning operations in the

Port of Maizuru, the potential release load of organic matter and noxious substances from the wood and bark into the seawater should be estimated. However,

since no such investigations have been conducted, the following estimations

were made based on the investigation data obtained at other ports.

The sinking wood and bark cause two adverse effects. First, deposition

on the sea bottom has a considerable influence upon benthos and consequently

upon fishery. Second, organic matter released from sinking wood and bark

" causes a degeneration in the quality of the seawater environment (increase in

. COD) in the bay.

A particularly large amount of pieces of bark resulted from the pusher

and barge carrying system adopted around 1975 for unloading timber from the

U.S.S.R. This system discharged wood in large quantities onto the sea surface

at one time, thereby peeling off large amounts of bark pieces by friction during discharge operations. At the same time a heavy load of bark within the

cargo hold was flushed into the sea. This method naturally invited opposition

from fishermen. Today, unloading is conducted by the conventional method:

timber is dropped onto the sea surface by a derrick crane on a wood carrier or ''

a mobile crane on a wharf.

Bark is peeled off either inside the cargo holds during loading and

transporting or at wharves or in anchorages where wood is discharged onto the

surface.

388

%.24

" ', ". .. '., .,.. ... ." -... .'..'..',. " .'. .'..'..'.°'.." "%'." . '.." . "..... ... ... ". " ....... ... . . .. ',. ... ..... ,.-....' .. '. -.... ' - .. ' '.... -..
The ratio of the total volume of bark to wood is usually about 12%. The

ratio of bark peeled off in a cargo hold and at a wharf to the total volume of

wood unloaded is estimated to be 1% and 0.5 - 2.0%, respectively, although, in

the latter case, the value varies largely depending on how the timber is

handled (for example, the volume of peeled off bark increases when the timber

is counted, measured, and classified because the timber is handled piece by

piece). The peeling-off rate for northern wood is estimated to be 0.5 - 0.8%.

The peeling-off rate of bark during unloading of timber onto the sea surface

varies by the kind of timber, and, according to the investigation at the Port

of Maizuru, is approximately 0.5% for northern wood from U.S.S.R., approximately 0.3% for American wood, and approximately 0.1% or less for southern

wood. The small value for southern wood (mainly from Malasia) may be explained by the fact that lauan, which comprises the majority of the southern

wood unloaded at the Port of Maizuru, is shipped primarily with the bark

stripped off at the port of shipment. However, Joncon and Jelton, new offerings in the southern wood market as alternatives for lauan, leave a heavy load

of bark behind, sometimes exceeding 5% of the total cargo volume.

These discussions include only bark; however, organic substances are also

released from the timber itself. It should be noted that the release occurs

from sinking wood as well as from wood in the timber ponds.

Figure 4 is a simplified illustration of this release mechanism.

Admittedly, nature's self-cleaning system (for example, bacteria) contributes

to the process of conversion of organic matter into inorganic matter. This

process, however, will not be included in the discussion below. . .. .

3 When V(m ) of wood is transported by a timber freighter, a1 (Z) of bark

will be left inside the hold. During the several months of storing in timber

ponds following the discharge onto the sea surface until the time of landing,

a (%) of bark peels off the wood to sink or float in the water. During this

22

period, 1, t2' and m 1 (mg/cm /day) of COD are released from the cut end

peeled-off sections on the cylindrical surface, and bark surface of wood,

respectively, while (mg/cm2 /day) of COD is released from the free bark into

the water. The COD release from the sinking bark in the past is

2 in(mg/cm /day). In terms of weight, the COD release from a unit weight of

bark is m1 ' (mg/g/day) for the cylindrical surface, m2 ' (mg/g/day) for the

both surfaces of the free bark, and m 3 ' (mg/g/day) for the sunken bark on the

sea bottom.

To obtain a unit volume for contamination such as COD released from wood,

experimental volume for unit area of the cut ends, peeled-off sections on the --

cylindrical surface, and bark surfaces (9 VL (S 2' c2' ml, m2. n 2 m3) i 3 )mstbedeer must be deter- .

mined. At the same time the cut end area (S m2), the cylindrical surface

area (SB cm2 ), the area of peeled-off sections on the cylindrical surfaces

(SB cm 2), the area of unpeeled sections on the cylindrical surface (outer

389

- . ..' :-'. ":.- :' d "- " ".' •.'','-.- "..:.' .' ' .'_,' ' =' '..: , :._ _:" :' _.' -".'_.' .'_.":. .. . .' . ! ''.-" .T .- -' '",.
Discharge on the sea surface Cylindrical surface

), Quay %

Cut end face YA1

Peeling-off

Bark

~* X . **. .. • -. ' " --. .-

inking b r....

3 V: Volume of wood (m)

*Peeling-off rate for bark

a1: In a cargo hold(%

a 2 : In timber ponds(.

a :During wood handling, released load of COD from wood()

2 i: From the cut end face (mg/cm

P i From the peeled-off sections on the cylindrical surface of wood 2 2

(mg/cm"/

" Release load of COD from bark

ml(mg/cm2), m 1 (mg/g): From the surface of bark

S(mg/cm2 m2 ' (mg/g): From both surfaces of free bark in the water

m 3 (mg/cm 2), m3 ' (mg/g): From surfaces of sinking bark

Figure 4. Release mechanism of organic matter due to wood handling

on the sea surface

bark surface) cm")c bot surface ireas of free bark (SD cm ), and surface

areas of sinking bark cm) per I m of wood should also be calculated.

3 The wood contamination unit per 1 m3 , W, is obtained from the following

equation:

W ff S +2. SB' + m.S' + m2.SD + mS3.S E

390

- . * .* .]
Assuming the release load per unit area of the heartwood and sapwood (see

Figure 5) on the cut end to be k and £2 and the heartwood rate H, the

equation will be: 11-12'

W = 111HSA + 1 12(1 - H)SA + L2SB + mIS c' + m2 SD + m3SE (2)

Using SA and SB, Equation 2 can be expressed as follows:

2 2

W 11HS A + X12 (1 H)SA + Z2 aiSB + m1 ( a i)SB

(3) + m2S + m3S

2D 3E

Assuming that all the free bark sinks rapidly, and neglecting the release -

load from the accumulated sunken bark, we may write as follows:

2 2

W = £11HS + Z (1+ H Z aSB + ml(I - a )S 11 A 12 5 A +22 a 1 IS i=1 i=l

(4) S..

2

3 iB1 

Cut end face

Sapwood Heartwood

Bark

Outer bark face

Cylindrical surface Releasing face

Reeeinlfc

Releasing face

Figure 5. Names for releasing faces

The last term of Equation 4 will be expressed as m a S in the case

where bark remains inside a hold.

In the experiments conducted by the First District Port Construction

Bureau, Ministry of Transport, the values shown in Table 5 are proposed as the

release values per unit area of each section of wood for each kind of wood.

3

The total release per 1 m' of wood is shown in Table 6 (the influence of

bacteria is eliminated by sterilization).

391
TABLE 5. RELEASE PER UNIT AREA OF AN INDIVIDUAL SECTION OF

WOOD (mg/cm2 /day)

Western

Larch (Wood Hemlock Lauan Cedar

of Northern (American (Yellow Lauan (Red (Domestic

Origin) Wood) Seria) Lauan) Wood)

Cut end face

t heartwood 0.823 0.18 0.045 0.0345 0.18

112 sapwood 0.085 0.12 -- 0.095

2 peeled-off sec- 0.113 0.095 0.20 0.012 0.04

"* -tions of the

cylindrical

surface

Bark

m outer bark 0.0358 0.065 .... 0.03

m free bark 0.039 0.08 .... 0.06

The volume of timber handling on the sea surface in the port of Maizuru

was, as seen in Table 7, approximately 320,000 m3 (290,000 tons) in 1983,

whose unloading operation was conducted at three separate places (Figure 2).

Each handling site has its own adjacent timber pond where unloaded wood

*is towed. In addition to these, in Ookimi District, at the exclusive dolphin

for wood, timber is unloaded inside the water area separated from the

anchorage by sheet piles, and stored in the Ookimi Timber Pond.

Using a conversion factor of 1.13 cubic meters per ton, Table 7 shows the

volume of imported wood, classified by wood origin, and the total number of

wood carriers employed over a 3-year period. The annual volume of wood handled at these sites over the 3-year period was 320,000 m 3 for the wood of

northern origin, 70,000 m 3 for American wood, and 150,000 m 3 for the wood of

* southern origin. The annual volume of bark peeled off from this volume of

wood is estimated to be 1,600 m (650 m excepting Ookimi) for northern tim3 3 3 3 ber, 220 m (180 m3 ) for American wood, and 150 m (150 m 3) for southern timber, totaling 1,970 m 3 (980 m3 ).

392 • °1
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Table 3 shows the recovered volume of sinking bark and Table 4 the volume

* of floating bark recovered by the cleaning boat, "Sokaku Maru." The total

volume of the recovered bark was 1,275 m in 1981, 1,378 m in 1982, and

1,257 m3 in 1983.

If no recovery operation were carried out and peeled-off bark were

allowed to accumulate to 30 cm thick, the sea bottom area covered with peeled- .

off bark would be approximately 6,000 m , and the annual volume of organic

matter released into the seawater from free bark would be (when converted into

COD) 73.4 kg for northern timber and 64.4 kg for American timber, with a total

volume of 137.8 kg (since the southern timber unit is not known, it was not

included in this estimation). From this, it can be concluded that bark ... "

recovery operations may be effective in reducing this potential contaminant

release load into the seawater.

The annual mean recovery volume of sinking wood over the past 3-year

3 period was 500 m . When converted into volume of organic matter released by

using the release rate for northern timber, the value is 1.31 kg annually, and

is 1.60 kg annually when converted by using the release rate and the cargo

rate for the wood of northern, southern, and American origin. These values

suggest the effectiveness of the recovery work in reducing the potential

* organic load.

For reference, seawater quality results determined in the Port of Maizuru

are shown in Figures 6 and 7. The marine environmental standards for the port

of Maizuru were set in 1975. Since then, periodic investigations of seawater

quality have been conducted to monitor the achievement rate of these

standards.

Furthermore, in Maizuru, the public desire for pure water is particularly

strong when compared with the people in other Districts. The carp which are

stocked in the River Takano flowing into Maizuru Bay are one example of the '"SJ -I

wisdom of the local people to help the self-cleaning system of nature, and it

goes without saying that nobody would dare catch the carp.

FUTURE ENVIRONMENTAL CONSERVATION IN THE PORT OF MAIZURU

Since the Port of Maizuru handles a large volume of wood, which accounts

for a major portion of the imported goods, there are demands for environmental

protection and improvement of the bay to counteract the seawater pollution

caused by wood handling on the surface. This local demand is mounting as the

nationwide social climate to place more importance on the environmental

conservation grows. In the course of negotiations for fishery compensation

relating to port improvement, the fishery cooperatives operating in the bay

strongly demand marine environmental protection as well as fishery promotion

policies.

To meet these demands from the local residents, the authors are committed

to promote the port improvement plan by constructing an exclusive berth for

timber in the Kita District and dolphins in the Kita and Taira Districts with

the aim of eliminating timber handling on the sea surface.

395

. ..... ... ..... ... ..... .. .. .. .. .. .. ..
Pon of Bakuchi

Pain.

Miyazak Nam of monitoring stations

for eOfvirOminental standards

:.:::: enbutasihanl frontage

Narazaki frontage

Figure 6. Monitoring stations for environmental standards

(Type A according to Japanese Environmental

Water Quality Standards as amended 1975.)

3.0 R

43u

Ebis frotaitl 

Naraliki frontage

1.0 Kingyobana frontage

Figure 7. Change in mean COD at monitoring stations

396

*~~~~ . I.. . % 
REFERENCE

1.The First District Port Construction Bureau, Ministry of Transport: The

* 18th Briefing Session on the Works in the Jurisdiction "On the Wood

Contamination Unit". 1980, 2.

.. ;

397

7(
A.-" -. o-.

THE MUSSEL WATCH PROGRAM/MONITORING THE LONG-TERM EFFECTS

OF DREDGED MATERIAL DISPOSAL IN NEW ENGLAND WATERS

R. C. Semonian

C. J. Lindsay

US Army Corps of Engineers, New England Division

424 Trapelo Road

Waltham, Massachusetts 02254-9419

ABSTRACT

The New England Division Corps of Engineers (NED)

began studying the effects of disposal of dredged

material in marine waters in 1969 and has continued

this effort under the Disposal Area Monitoring System

(DAMOS).

The "Mussel Watch" Program is one of the stateof-the-art techniques incorporated into DAMOS to

assess bioaccumulation due to disposal of dredged

material. Findings to date show the mussel to be an

excellent test organism which, together with suitable

field techniques, may be used to monitor effects of

disposal over the long term.

INTRODUCTION

The purpose of monitoring the disposal of dredged material in ocean

waters is to identify, measure, and quantify significant impacts to the marine

environment surrounding the point of discharge. It is reasonable for a project manager charged with the task of designing a monitoring plan to consider

obvious factors such as the character of the material to be dredged and the

hydrological and biological regimes of the disposal sites. He can then base

his scientific design on a program of field observations and measurements in

terms of physical, chemical, and biological parameters utilizing proven methodologies and standardized practices. This was the approach used by the New

England Division in early monitoring efforts (1969) and it was the deficiencies of this approach that led to the formalizing of our Disposal Area

Monitoring System and the evolution of our mussel program.

Some 15 years ago the New England Division began its pursuit of the environmental consequences of dredged material disposal by contracting marine

laboratories and universities to conduct field observations of specific dump- '

ing events. Simply put, our approach was to develop a predisposal baseline of

the disposal site in physical, chemical, and biological parameters against

which subsequent measurements taken during and after disposal might be compared. At this point in time, dredged material monitoring was in its infancy

398

L , , ., .. ._._........ .._..:..,, :.:.:_ .:- .::.. .. -.-. : :..... ,_;.- .2 ;.;: _.;.: .; H.:: ::
and, since there were no established guidelines to follow, principal investigators were allowed much latitude in the experimental design of each contracted task. As studies were reported we became aware that there were few

standardized methods in the marine community for acquiring data and that

scientists of the same discipline used different methodologies for similar

tasks. Further, to our dismay, we found that scientists of differing disciplines were proprietary in their thinking and rarely gave consideration of

possible interaction with other sciences involved. Although data acquired

were extensive and reported findings accurate, we realized that our efforts K"

were too fragmented and lacked compatible continuity. Recognizing that a more

structured and interdisciplinary program would contribute significantly to our

monitoring efforts, the Division formalized the Disposal Area Monitoring System, or DAMOS.

DAMOS

DAMOS, formally organized in 1977, remains as the monitoring arm of the

New England Division. Through it we have standardized our monitoring designs

at ten open water sites along our coastline and have applied a multidisciplined approach to all investigations. Scientists participating in the DAMOS

program constitute a highly experienced, multidisciplined team that meets at

least annually for a peer review of findings and to collaborate on the design

of upcoming activities. Team members are encouraged to suggest new concepts

and innovative ideas for consideration by the team. As a result, DAMOS has

been a learning experience, developmental, and often at the state of the art.

The use of mussels as pollution indicators in dredged material management

stands as an example of the DAMOS approach in that it represents monitoring

concepts that have the potential of integrating physical, chemical, and biological processes that occur with the disposal of dredged material in the

marine environment.

The role of marine bivalve molluscs in extracting trace metals from the

marine environment and concentrating the metals in their tissues had been well

established prior to our integrating a mussel program in DAMOS. And, in fact,

bivalves had been used as sentinel organisms in monitoring environmental quality. Studies had shown that the uptake of trace metals by bivalve molluscs is

reflective of metals in the environment--water temperature, physiological

state, and organism size are other factors--and that the uptake reversed as

the concentration of metals diminished. Evidence seemed to indicate that an

appropriate bivalve mollusc might be ideally suited to monitor the transport

and fate of those contaminants of concern perceived to be released into the

marine environment by the dredging and open water disposal of enriched sedi-

% ments. With this premise in mind, the DAMOS mussel program was initiated in

1978 under the direction of Dr. S. Y. Feng of the University of Connecticut. ..

Initial study goals were to determine if there were significant increases in

trace metals in our organisms attributable to the disposal of dredged material "

and to develop effective field deployment and retrieval for the mussel monitoring platforms (2,5).

Although several species of filter-feeding bivalve molluscs are known to

reflect changes in exposure to heavy metals, not all are suitable for longterm monitoring. Robust organisms, active through a major portion of the year

and of sufficient size and local abundance to permit frequent sampling, are

needed. The horse mussel (Modiolus modiv0us) and the blue mussel (8yti"u.

399

.-
- ~: k . .~ 

edulia) were selected for monitoring DAMOS sites located north and south,

respectively, of Cape Cod which separates the two tidal systems impacting the

New England coastline.

The plan was to establish experimental stations at four northern and six

southern disposal sites. Prior to deployment, single stock populations of

M. modiolus with relatively low trace metal content were selected for the

northern sites and designated as a reference population. Populations of blue

mussels, M. edulis, from a single site in Long Island Sound were selected as

the reference stock for the disposal sites in that estuary.

Groups of 50 mussels were placed in 35 polyethylene mesh bags and

attached to polyvinyl chloride (PVC) platforms (1 m x I m x I m) with concrete

footings. Platforms were lowered by shipboard winch and Loran C positions C.-'

recorded. Subsurface pop-up floats, detachable surface buoys, and subsurface

sonic pingers were incorporated in the platforms to facilitate retrieval by

divers using SCUBA for subsequent sampling of the mussels. Initially we L'

sampled mussels on a quarterly basis but have found that monthly sampling is

better suited to observing subtle temporal variations (2,5,7).

During each sampling period, duplicate samples of 8 mussels were coliected and, for baseline data, 10 replicates were used. Mussels were cleaned,

measured, shucked, and freeze dried. The process followed for the trace %

metals analyses is too extensive to include in this paper, but is thoroughly

discussed in DAMOS reports--numbers 20 thru 22 and the 1980 annual report,

among others. However, we can emphasize that extreme care was exercised to

minimize contamination (2-5).

Since mussels were collected from natural (reference) populations and

experimentally transplanted to dump sites, we were ultimately studying the

effects of dredged material disposal by comparing fitness of one population in

two environments.

One of the major difficulties in the interpretation of results is the

separation of the effects of normal physiological activities on trace metal

uptake from uptake that is ascribable to anthropogenic input. Implicit in

field experiments is the fact that data sets are correlational and cannot be

assumed, unlike laboratory experimentation where independent variables can be

carefully controlled and altered one at a time and the response of the organism to them accurately measured.

Two issues are addressed in the analysis of mussel trace metal data.

First, we identified factors such as wet/dry ratio, length of mussels, and

dredge volume, which singly or in combination with river runoff and temperature could be correlated to metal concentrations in mussels. Secondly, differing metal concentrations in mussels were determined.

Independent variables were categorized as intrinsic--i.e., variables

associated with the physiological condition and growth of mussels expressed as

the wet/dry ratio of tissues and shell length--and extrinsic factors that are

variables in the environment, such as dredged material volume, river runoff,

and water temperature. Since the purpose of the study was to determine

400

Fir...-

-. 'V
whether dredged material disposal, an extrinsic factor, is related to metal

concentrations in mussels, it was extremely important that variance in metals

concentrations due to intrinsic factors be accounted for or removed.

Data were subjected to intensive statistical analysis. The results indicated that peak concentrations tend to occur during periods of increased

suspended load in the water column attributable both to natural meteorological

events and dredged material disposal. These observations, when compared with

sediment transport studies being conducted under the DAMOS program, showed

that spatial and temporal effects of dredged material are several orders of

magnitude smaller than those induced by natural storm events (4,7).

We have used mussels as sentinel organisms for 6 years now and have

expanded their applicability to encompass site designation investigation,

capping studies, and a cooperative effort with the joint Environmental Protection Agency/Corps Field Verification Program being conducted in Long Island

Sound. In addition, levels of polychorinated biphenyls (PCB's) have been

monitored and Dr. Feng's research has carried into mussel histology, in particular gonadal development and reproductive pathology (1,6,7).

Our current program is directed toward a single site in western Long

Island Sound where three platforms have been deployed--on the mound center, at

the mound periphery, and at the area reference station. An additional platform is maintained at the master reference station in eastern Long Island

Sound to provide data on the stock population. Samples are collected monthly

and analyzed for heavy metals and PCB's and subjected to histological examinations. It is hoped that the data will allow the perspective evaluation of

disposal effects relative to the effects of other significant variables at

this already stressed area.

Future plans will consider analysis of polynuclear aromatic hydrocarbons

(PAH's) and metallothioneins in addition to the effort described above. Such

changes will be assessed relative to program objectives and application to

disposal concerns.

REFERENCES

1. Arimoto, R., and Feng, S. Y. 1980. "Changes in the Levels of PCB's in

M~tilus edulis Associated with Dredge Spoil Disposal," DAMOS Contribution

#10, Unpublished report, Science Applications, Inc., Newport, R. I. Submitted to US Army Corps of Engineers, New England Division, Waltham,

Mass., 27 pp.

2. Arimoto, R., Haddad, E. M., and Feng, S. Y. 1979. "Histological Examinations of Gonadal Development in Mtilus edutis and Modiolus modious,"

DAMOS Annual Data Report - Proceedings of Symposium, May 1979, Vol 2,

Unpublished report, Naval Underwater Systems Center, Newport, R. I. Submitted to US Army Corps of Engineers, New England Division, Waltham,

Mass., pp 829-845.

3. Arimoto, R., and Feng, S. Y. 1984. "Histological Studies of Mussels from

Dredged Material Disposal Sites," DAMOS Contribution #20, Unpublished

401

.*:.~v~* *.-. .. .-.
report, Marine Science Institute, University of Connecticut, Groton, Conn.

Submitted to US Army Corps of Engineers, New England Division, Waltham,

Mass., 25 pp.

4. DeGroursey, R. E., Watson, J. K., Gillo, R. V., Arimoto, R., and Feng,

S. Y. 1984. "Field Techniques for In Situ Long Term Monitoring of the

Effects of Dredged Material Disposal on the Mussel, Mytilus edulis,"

Unpublished draft report, Marine Science Institute, University of Connecticut, Groton, Conn. Submitted to US Army Corps of Engineers, New

England Division, Waltham, Mass., 18 pp.

5. Feng, S. Y. 1980. "Mussel Watch Program," DAMOS Annual Report 1980,

Vol 2, R. W. Morton, and C. Karp, eds., Unpublished report, Science Applications, Inc., Newport, R. I. Submitted to US Army Corps of Engineers,

New England, Waltham, Mass., pp 601-644.

6. Feng, S. Y. 1982. "Mussel Watch Program: Monitoring of the "Capping"

Procedure Using MAtilus edutis at the Central Long Island Sound Disposal

Site," DAMOS Contribution #22, Unpublished report, Science Applications,

Inc., Newport, R. I. Submitted to US Army Corps of Engineers, New England

Division, Waltham, Mass., 34 pp.

7. Feng, S. Y. 1982. "Mussel Watch Program: Eastern Long Island Sound Dis- ".'

posal Site Monitoring Projects 1977-1979," DAMOS Contribution #21, Unpublished report, Science Applications, Inc., Newport, R. I. Submitted to

US Army Corps of Engineers, New England Division, Waltham, Mass., 39 pp.

402_

- , -.

402."-".•".'
ENVIRONMENTAL AND WATER QUALITY OPERATIONAL STUDIES (EWQOS) -

APPLICATION TO LAKE RESTORATION

J. L. Mahloch

US Army Engineer Waterways Experiment Station."

PO Box 631, Vicksburg, Miss. 39180-0631

ABSTRACT

EWQOS is the largest funded Corps research program directed at solving the environmental quality

problems of reservoirs and inland waterways. Application of EWQOS technology to lake restoration falls

into two categories: (a) evaluation for management

decisions, and (b) specific techniques for improving

environmental quality. Management decisions revolve

around the ability to predict or monitor the response

of a lake to proposed restoration techniques. Specific techniques to improve lake water quality such as

aeration, destratification, and localized mixing were

also developed under the EWQOS Program, and design

procedures are available. A common manifestation of

lake water quality problems is the appearance of

nuisance algae blooms. Research in EWQOS has produced

a review of common algal control techniques, algae

succession data in response to eutrophy, and a new

technique using destabilization and nutrient additions

to promote the dominance of more desirable algal

species. Many of the techniques applicable to lake

restoration have been field tested or verified under

EWQOS to facilitate their implementation.

INTRODUCT ION

The Environmental and Water Quality Operational Studies (EWQOS) Program

is currently one of the largest research and development efforts of the Corps

of Engineers (CE). EWQOS has as an objective to develop technology for the CE

to attain national environmental quality objectives while meeting authorized

project purposes. While the scope of EWQOS covers all inland water resource

projects of the CE, this paper will be confined to results from research on

reservoir projects.

Reservoir projects of the CE face a myriad of environmental quality problems, ranging from impacts of releases on downstream aquatic habitat to problems associated with fluctuating pool elevations. These problems are com-.'

pounded by operational constraints required to meet project purposes. Often,

proposed solutions to water quality problems must be modified so as not to

impose an unreasonable or uneconomical constraint on operational personnel.

403 "'

.-... ,'-._,......,......................-.,.-..-...-.............................-....................,.-....-.-... .,
One key problem facing CE reservoir projects involves the environmental ::

impacts associated with increasing eutrophication. In developing solutions to

this problem, differences between natural lakes and reservoirs must be kept in

mind to avoid conflicts mentioned above; nevertheless, solutions to eutrophication problems developed within EWQOS have potential application to lake

restoration.

Research conducted on reservoir projects within EWQOS has focused on a

number of environmental problems. In addition to research tasks that address

such topics as numerical modeling, solutions to specific problems, or design

and operational guidance, a key area of reservoir research has been extensive

and comprehensive field studies. Field studies on reservoir projects complement research tasks by providing necessary background data to evaluate problems, develop solutions, and permit verification of many techniques developed.

While many reservoirs were used in these field studies, Eau Galle reservoir in

Wisconsin provided a majority of the information applicable to lake restora- - tion. Field studies, by virtue of the experience gained, also yield valuable

insight into the development of monitoring guidance and procedures required to ..,

solve specific environmental problems.

APPROACH TO LAKE RESTORATION

In approaching the problem of lake restoration in response to eutrophication, a number of factors must be considered in developing a comprehensive

solution: (a) a lake exhibits a unique condition or problem, often as a function of its design or operation, (b) given this condition, project modification (action) to improve environmental quality is performed, and (c) evaluation techniques are required to bridge the gap between condition and action to

determine if solutions applied are feasible or successful.

Condition of CE Reservoirs

CE reservoirs often form unique ecosystems because of their design and

operation. In comparison to natural lakes, they are generally larger, deeper,

morphologically more complex, and have shorter hydraulic detention times (4).

Many reservoirs are dominated by an advective flow that affects nutrient transport and biological response of the project. In the United States, many reservoir projects are constructed in areas where there are few natural lakes and

the population is dense, often to meet project objectives such as flood control or water supply. Because of this situation, CE reservoirs have historically received large nutrient loads either by point or nonpoint sources.

These characteristics have made eutrophication a major problem for many CE .' -

projects.

Eutrophication may adversely impact projects in a number of ways,

although the primary symptomatic response is increased blooms of nuisance

algal species. Nuisance algae species generally include the blue-greens and

dinoflagellates. Increased productivity of nuisance algae may affect project

activities by impacting recreation or causing taste and odor problems for

water supply, and degrading biomass may adversely affect project water

quality (18). Methods to control nutrient loadings are often outside the

agency mission, and internal nutrient cycling can override any external controls; consequently, the only remedial action remaining is the alteration of

algal production or succession to provide symptomatic relief for the problem.

404

%
Evaluation Techniques

Evaluation of the response of reservoirs to changes designed to reduce

impacts associated with accelerated eutrophication is critical to any program

of remedial action. In many areas the use of evaluation procedures can be very

effective in determining the types of remedial action that are likely to be

successful for a project. These procedures offer unique advantages to the

decision-maker who is faced with several alternatives that may be costly to

implement. Two principal techniques for project evaluation that have been

developed from EWQOS research are nutrient loading models and simulation

models.

Nutrient loading models developed under EWQOS were based on analysis of a

comprehensive water quality data base (20, 21). Regression equations were

developed to assess reservoir response to changes in nutrient concentration,

in terms of chlorophyll a, transparency, organics, and hypolimnetic oxygen

demand. An example of the network of equations developed for this purpose is

*" presented as Figure 1 (22). While these nutrient loading models may be very

INFLOW TOTAL P HYPOLIMNION OXYGEN * '" INFLOW ORTHO-P -4(7)- RESERVOIR DEPLETION RATE NI MEAN DEPTH -- ' TOTALP

HYDRAULIC RESIDENCE TIME

COMPOSITE NUTRIENT 4

CONCENTRATION

INFLOW TOTAL N

INFLOW INORG N 2 RESERVOIR

MEAN DEPTH TOTAL

HYDRAULIC RESIDENCE

MIXED LAYER DEPTH CHLOROPHYLL-A PRINCIPAL

SUMMER RESIDENCE TIME 8 COMPONENTS

FOR RESPONSE

5 TRANSPARENCY

REGION

LATITUDE ORGANIC N

TOTAL P NON-ALGAL

SUMMER RESIDENCE TIME TURBIDITY

MEAN DEPTH 7 PARTICULATE P

DENOTES A PARTICULAR MODEL

Figure 1. Network of nutrient loading models for evaluating

reservoir eutrophication.

helpful in identifying and pinpointing causal relationships associated with

reservoir eutrophication, they are based on certain assumptions; therefore,

their use is limited. Primary limitations result from the range of the data

base employed, the fact that conditions are reservoir averaged, and errors are

associated with model use. Nevertheless, nutrient loading models represent

excellent procedures for screening alternatives and conducting an initial

evaluation of project response. Z4

405

'a, . . ..:., ,,.:

. . .. . . - . . - * .. 'U . . --. . . . . . . . . . - ' " = . . ll l - =
WL

Simulation models are numerical techniques designed to evaluate the water

quality of a reservoir in response to changing conditions. By their very

design, simulation models are more general and useful than regression models;

however, they are also more costly and time consuming. The water quality

- models developed under EWQOS are capable of dynamically simulating reservoirs

. in a one- or two-dimensional sense. In addition to complete prediction of

" common water quality parameters, higher trophic levels, such as algae, are

also simulated by these models (7, 9, 10). In this case, the magnitude, com-

*' position, and timing of algal blooms and factors controlling algal growth can

be predicted. An example of these types of predictions for structural and

operational changes to proposed CE reservoirs is shown in Figure 2 (18).

These models can give detailed information on the response of a project to

proposed changes for relieving the symptoms of eutrophication. In many cases

the simulation models developed under EWQOS have had extensive verification,

and rate coefficients required for application are based on results of exten- . -

sive field studies mentioned earlier. Although this imparts a significant

advantage to model use, the user must always remember that certain aggregations are inherent in model formulation; therefore, interpretation of output

can be tedious and complicated.

Remedial Actions for Reservoirs

Faced with a lake or reservoir exhibiting accelerated eutrophication, an

agency may have several options for remedial action. The remainder of this

paper discusses options designed to retard the development of nuisance algal .

blooms associated with eutrophication.

In many instances, CE reservoirs follow a rather typical succession of

algae common to many dimictic, North temperate lakes. These reservoirs exhibit

an early spring bloom of diatoms, followed by green, blue-green, and dinoflagellate algae. After fall turnover, a diatom bloom may reoccur. The

blue-greens and dinoflagellates are the most troublesome and would be the primary target for remedial action. Remedial actions might include elimination

of these species in the successional cycle and/or reduction in the total J&

amount of algal biomass produced. Major reductions in productivity may be

undesirable for most CE projects because of associated impacts (e.g., reduc- .'

tion of reservoir fisheries); consequently, it is more desirable to alter

algal community composition than to reduce overall productivity.

Early in EWQOS, a summary of common algal control and management techniques was compiled (6). Techniques surveyed included biological, chemical,

and physical methods and a combination of these for algal control. This summary offers an excellent initial assessment of commonly used control techniques. Because of differences between natural lakes and reservoirs (primarily operational), many of the techniques presented in this summary may not

be directly applicable to CE reservoirs. Therefore, a workshop on algal

management and control was conducted (19) to evaluate major algal control

techniques. The workshop concentrated on techniques for nutrient control,

aeration/destratification, biological control (i.e., grazing, cyanophages),

and chemical usage. Although the success of many techniques was documented

for specific cases, no technique appeared universally successful or appropriate. A conclusion of the workshop was that emphasis needed to be placed on

406

-____-_. __ . -. ~-*
18

LEGEND

15 -

ESELECTIVE WITHDRAWAL

12 - E BOTTOM WITHDRAWAL

a..

(2

6

3

01o

a. STRUCTURAL MODIFICATION

15

LEGEND

12 - .~

S65 M3 /S ~ .

48 M3 /S

39

(D26

3

0

108 138 168 198 228 258 288 318

JULIAN DAY

1975

b. OPERATIONAL MODIFICATION

Figure 2. Algae response to project changes.

407 .%
algae control techniques that minimize adverse environmental impacts, specifi- .-*

cally those techniques that take advantage of factors influencing algae composition and productivity.

In many cases, accelerated eutrophication in reservoirs is reflected in

poor water quality. Often most significant is a depression of hypolimnetic

dissolved oxygen. Remedial techniques may be applied to improve water quality,

but related (specifically, biological) impacts have been only superficially

considered. Technology related to reservoir mixing, destratification, and

aeration has been developed within EWQOS, and a variety of documentation

exists as guidance in the application of these techniques (3, 5). The

environmental aspects of applying these techniques have also been

evaluated (11).

Another example of a physical solution to nuisance algae control is the

use of pool elevation control (6). While this may be successful in altering

successional patterns of algae, care must be exercised in timing and the degree

of change. A recent EWQOS publication has documented the effect of pool elevation changes on reservoir fisheries (12) and can be used for an initial evaluation if this technique is applied.

STUDIES AT EAU GALLE RESERVOIR

On the basis of available information, a comprehensive study of algal

control was undertaken at Eau Galle reservoir, one of the major reservoir

field study sites in EWQOS. Two primary factors influenced the direction of

the work performed at Eau Galle reservoir. First, there was a general lack of

a comprehensive study of algae control within CE impoundments. Eau Galle

reservoir may be classified as eutrophic, exhibiting intense algal blooms, and

is a rather small reservoir; consequently, intensive studies could be undertaken at a rather low investment in resources. Second, because of a coordinated field study, factors influencing algae succession and production could

be identified, and experimental control could be attempted on the basis of

this information.

Eau Galle Reservoir

Eau Galle Reservoir is located in west-central Wisconsin and was created

by the impoundment of the Eau Galle River in September 1968 (8). The primary

purpose of the project is flood control. Normal releases are made through an

uncontrolled morning-glory structure and a low-level gated outlet conduit.

The lake is dimictic, and ice cover usually persists from December until late

March. A summary of the physical and water quality characteristics of the

lake is provided in Table 1.

Algae Composition and Succession

A major prerequisite for establishing a control program for algae is a ,.

thorough understanding of phytoplankton ecology, including factors controlling

growth and succession. A comprehensive study of phytoplankton composition and

succession was undertaken at Eau Galle reservoir in association with other

limnological studies. Methods included algal enumeration, taxonomic identification, biomass, chlorophyll a, and productivity, which are documented in

408

"-" " " -" " """ " '-"'".'."'"--.'--'""-"'-'";'i '" ".' "'"-"'°'. " ~i~~i~ '- -'- . l '-; ''-' -' " ,:, ,t,, .' . _ \ , _*,*
TABLE 1. CHARACTERISTICS OF EAU GALLE RESERVOIR 0. -

Parameter Value

Physical

Surface area 0.6 kin

6 Volume 1.5 x 10 m

Depth (mean, max.) 3.2, 9.0 m

Shoreline development ratio 1.50

Drainage area 166 km2

Residence time 0.07 yr

Water Quality*

Total alkalinity 152.3 mg/£

Total carbon 47.4 mg/.

Total phosphorus 0.091 mg/i

Total nitrogen 1.65 mg/"

Chlorophyll a 31.9 ug/

• Mean surface value (0-2 m) from six stations for years 1978-1981.

detail elsewhere (1). Sampling stations are shown in Figure 3. Studies were

initiated in 1981 and are continuing in conjunction with the experimental work

on algae control.

Results from Eau Galle (1) showed a seasonal succession of algae typical

of eutrophic, temperate lakes, with spring diatom followed by summer phytoplankton followed by fall diatoms (Figure 4). In 1981, the cyanophyte

Aphamizomenon and the pyrrhophyte Ceratium predominated the summer phytoplankton. Algal biomass during periods of peak production is comparable to other

temperate, eutrophic lakes. Patterns of succession were generally the same

during 1982 and 1983, although they were not as pronounced (data not presented).

Development of Algal Control Experiments

The success of earlier attempts to control nuisance algae have generally

been impaired due to an incomplete understanding of the specific environmental

factors controlling growth and succession. In a number of situations, experiments to improve lake water quality or to control algae have been inconclusive

because associated limnological data on which to adequately judge the success

of techniques were not available (17).

409

.
i tSV RE

U5

'F41%

SCLEGEND

60-

EE CYANOPHYTA

EM BACILLARIOPHYTA

So- CHRYSOPHYTA

EIJPYRRHOPHYTA

40 OTHEFR

30

20

10

MONTH, 1981

Figure 4. Seasonal succession of algae at Eau Galle reservoir.

410
Results of algae community studies at Eau Galle suggest that mixing (or

the lack of mixing) and nutrient availability control algae succession.

Diatoms tend to predominate during mixed conditions because of high nutrients

(particularly silica) and suspension in the euphotic zone due to turbulence.

Depth of mixed layer appears to be critical to avoiding the loss of diatoms by

settling (13). As stratification occurs, species that can selectively migrate

in the water column (blue-greens, dinoflagellates) are favored. Reduced

nutrient availability, particularly nitrogen for the blue-greens, may contribute to their competitive advantage. Similar results have been reported elsewhere (13, 14, 15, 16), which indicates the importance of maiipulating

stability and nutrient availability as means for controlling algal succession

and biomass. In some cases, mixing may be counterproductive. While it ,"*

encourages a more desirable species (i.e. diatoms), increased nutrient availability from the hypolimnion and resuspension of resting forms (i.e. bluegreens) may offset any gain realized.,' '

-" .

Control Experiments at Eau Galle

Based on the above, a series of experiments were implemented at Eau Galle

during the summer of 1983. Experiments were conducted in polyethylene enclosures, 10 m in diameter, to minimize artificiality. A similar approach has

been used by others with success (14). Treatments used were mixing alone,

addition of silica, and a combination. Mixing was provided by a Garton pump

with a deflector plate to minimize sediment resuspension, and silica (sodium

metasilicate) was dissolved gradually in the enclosures during the experiment. ..

A separate enclosure was used as an experimental control, and the open water .'--

served as an overall control (2).

Results of these experiments are summarized in Figure 5 (2). Silica

treatment was ineffective for maintaining diatdms or suppressing the

LEGEND

CYANOPHYTE+ YROHT ALL OTHER +PRIOHT

7-°

60 -

10 MIXING

30 MXN

20 SI

10 CONTROL . •

MAY JUNE JULY AUG SEP

TIME, MO

Figure 5. Experimental control results at Eau Galle reservoir, 1983.

blue-greens. Silica addition and mixing in combination did not deter the

dominance of nuisance forms of algae (i.e., blue-greens and dinoflagellates),

a result similar to the findings of other investigators (14, 15). Mixing

alone resulted in a sustained diatom presence, but blue-green biomass was

411

• '.','.,' "'N " ' "..''.."".", ".'.'v''""'.'..'', " -. ""N " "¢ ' " . "" ,"" ", "" ."". ,' '. . . ..,,,,,, . ,.- V..,''
large, although the dinoflagellates were suppressed. Mixing may have provided

a source of blue-green algae as well as contributing to increased nutrient

supplies. This is particularly true in the case of Eau Galle reservoir, where

the water column is particularly shallow. In conclusion, results of mixing

" were favorable, although clearly there were other factors controlling algae

succession and production. At the end of these experiments, alum was added to

"- the silica plus mixing treatment in an attempt to control nutrient (phosphorus) availability. Although there was an immediate response (i.e., rever-

/ sion to green algae), it was too late in the experiment to confirm whether

this treatment would be successful over an entire season. This finding did

suggest that control of phosphorus availability in conjunction with mixing may

lead to more effective algae control (2).

Based on the results of experiments conducted during 1983, additional

-" experiments were designed for the 1984 season. Treatments currently being _ :

used include silica sand addition (bottom sealing), silica sand addition plus

mixing, alum addition, alum addition plus mixing, and a control. Experiments

are being conducted in a fashion similar to those of the 1983 season. Alum

addition is being used to control the availability of phosphorus. Silica sand

addition to the bottom is an attempt to control nutrient migration across the

sediment-water interface, to prevent reinnoculation of the water column, and

to provide a source of silica for diatoms. The mixing treatment was continued

because it appears to be a controlling factor in the maintenance of diatoms.

Preliminary results (after 6 weeks of investigation) suggest that all

treatments are successful. The succession seems more favorable, and the

amount of algae produced appears to be lower in all treatments. Confirmation

of these preliminary results will have to await a thorough analysis of the

1984 data. A demonstration project on the whole lake may be attempted in

1985.

SUMMARY

The EWQOS Program has produced many techniques that are applicable to

lake restoration. A variety of techniques plus guidance on sampling and data

% "analysis are available to assess problems, develop potential solutions, and

judge their effectiveness. Reviews of commonly employed techniques for algae

control and design guidance for physical alteration of lake environments are

also available. Efforts directed at controlling the primary problem associated

with eutrophication, the presence and abundance of nuisance algae, are presently under way. The advantages of the experimental techniques currently

under study are that they employ natural control mechanisms to affect algae

succession and production, and they can be applied to lakes with minimum

adverse environmental impacts.

ACKNOWLEDGMENTS

This study was supported by the Office, Chief of Engineers, under the

EWQOS Program. The author gratefully acknowledges the assistance of Dr. John

Barko, Environmental Laboratory, in the preparation and review of this paper.

412
I ~APPENDIX A: REFERENCES 4.

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Phytoplankton Community Composition in a Eutrophic Temperate Impoundment"

in preparation, US Army Engineer Waterways Experiment Station, Vicksburg,

Miss.

3. Dortch, M. S. 1979. "Artificial Destratification of Reservoirs,"

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5. Holland, J. P. 1984. "Parametric Investigation of Localized Mixing in Reservoirs," Technical Report E-84-7, US Army Engineer Waterways Experiment Station, Vicksburg, Miss. rUSEvrnet

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413

,r ' 'L. " "" , .. o ."o" " ",e °". " .'.. ' ,••''e ." '.".". .". . ,. .- '- ,, , . . ," • . . . . . . ." •
12. Ploskey, C. R., et al. 1984. "Effects of Water Levels and Hydrology on

Fisheries in Hydropower Storage, Hydropower Mainstream, and Flood Control

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13. Reynolds, C. S. 1976. "Successive and Vertical Distribution of

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14. Reynolds, C. S., et al. 1983. "Some Effects of Artificial Mixing on

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16. Steinberg, C. 1983. "Effects of Artificial Destratification on the

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17. Toetz, D. W. 1981. "Effects of Whole Lake Mixing on Water Quality and

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18. US Army Corps of Engineers. 1984. "Reservoir Water Quality," Draft

Engineer Manual, EM 1110-2-XXX, Washington, DC.

19. US Environmental Protection Agency. 1981. "Proceedings of the Workshop

on Algal Management and Control," Technical Report E-81-7, prepared for

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No. AD A101 554).

20. Walker, W. W., Jr. 1981. "Empirical Methods for Predicting Eutrophication in Impoundments; Report 1, Phase 1: Data Base Development," Technical Report E-81-9, prepared for US Army Engineer Waterways Experiment

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Station, Vicksburg, Miss.

4

414

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FIMED

DTIC