US Army Corps of Engineers

Water Resources Support Center .S ,TManagement of Bottom Sediments

Containing Toxic Substances

Proceedings of the 7th U. S./Japan

Experts Meeting

2-4 November 1981

New York City, USA

l&

DTIC

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C"ENT PART NOTICE

THIS PAPER IS A CO"ENT PART OF THE FOLLOWING COMPILATION REPORT:

(TITLE): Management of Bottom Sediments Containing Toxic Substances: Proceedings

of the U.S. Japan Exferts Meeting (7th) held at New York City on

2-4 November 1981.

(SOURE): Corps of Engineers, Fort Belvoir, VA. Water Resources Support Center

To ORDER Tw cOLETE COMILATION REPORT USE AD-A136 740

THE CUrl'PENT PART IS PROVIDED HERE TO ALLOW USERS ACCESS TO INDIVIDUALLY

AUTHORED SECTIONS OF PROCEEDINGS, ANNAtS, SYMPOSIA, ETC. HOWEVER, THE

CO1PONENT SHOULD BE CONSIDERED WITHIN THE CONTEXT OF THE OVERALL COMPILATION

REPORT AND NOT AS A STAND-ALONE TECHNICAL REPORT.

THE FOLLOWING COPIENT PART NUMBERS COMPRISE THE COI¶PILATION REPORT:

AD#:' TITLE:

AD-P002 392 Prospect of Sea Bottom Management in Ports and Harbors and Sea

Water Areas in Japan.

AD-PO02 393 Rescuing the Ports: Dredging and Disposal of Dredged Material

in the Operation and Maintainability of Ports throughout the

World.

AD-P002 394 Design and Construction of Fabric-Reinforced Dredged Material

Retaining Dikes.

AD-PJ02 395 Sand Overlaying for Sea Bottom Sediment Improvement by Conveyor

Barge.

AD-P002 396 Sand Overlaying for Bottom Sediment Improvement by Sand Spreade~r.

AD-P002 397 ; Studies on Capping of Contaminated Dredged Material in New

England Division.

AD-P002 398 0 'Capping' Procedures as an Alternative Technique to Isolate

Contaminated Dredge Material in the Marine Environment.

AD-P002 399 0 Studies on Capping of Contaminated Dredged Material by the

New York District, Corps of Engineers.

AD-P002 400 Experiences with the Stabilization Sediments.

AD-P002 401 PCB (Polychlorinated Biphenyls) Cleanup Activities on the

Upper Hudson River.

AD-P002 402 Productive Use of Calcined Sediment (Calcination of Sediment

for an Artificial Aggregate).

AD-P002 403 Several Solidified Sediment Examples.

AD-P002 404 James River, Virginia: Dredging Demonstration in Contaminated

Materisl (Kepone) Distpan versus Cutterhead.

AD-P002 405 Test Dredging of Bottom Sediments in Osaka Bay.

DTIC

JAN 1984

This document has boen approev'd

for public release and sale; its

distribution is unlimited. . A
CaNaONET PART NOTICE (coN')

AN: TITLE:

AD-P002 406 Management Tools for Assessment of Dredged Material

Impacts.

AD-P002 407 Purification of Water and Sediments Using Organisms

(Living Filter)--Removal of Suspended Solids and

Nutrients by Pharalmitas Comunis T. and Zostera Marina L.

AD-P002 406 The Effects of Nutrients Release from Sediments on the

Formation of Water Blooms.

AD-P002 439 Sumer Peak of Nutrient Concentrations in Lake Wtiter.

AD-P002 410 1981 Status Report on the Environental and Water Quality

Operational Studies Program.

AD-P002 411 Marine Technology for Environmental Problems: Some

Examples of Improved Systems on Workvessels.

AD-P002 412 Mount St. Helens Eruption, Corps of Engineers Restoration

Efforts.

AD-P002 413 The Water Quality Preservation Measures in Lake Biwa, the

Largest Lake in Japan.

Fu

is% sp4c al
Unclassified

SECURITY CLASSIFICATION OF THIS PAGE (9,% D- 1. d) REPOT DCUMNTAION AGE ,'• '/9 READ INSTRUCTIONS REPORT~~ ~ ~ ~ DOUETAINPAEjEFORE COMPLE-rIN FORM 1.| RErPORT MU69SER ' ", • fT A ,.I O N J6• 3. R t 1P1FN T'S C ATALOG NUM BER I ... 4. TITLF (-d• .btle) S. TYPE Of REPORT & PERIOD COVESE

MANAGEMENT OF BOTTOM SEDIMENTS CUNTAINING TOXI[C Final report

SUBSTANCES: PROCEEDINGS OF THE 7TH U. S./JAPAO 4- PEFORMNo o. REPORT NUM3ER

EXPERTS M"ETING _

7. AUTMO*(.) 8. CONTRACT OR GRANT NUMBERO'.)

S. PERFORMING ORGANIZATION NAME AhO ADORESS 10. PROGRAM ELEMENT,. PROJECT. TASK ARErA & ORK UMIT NUMB•ERS

Dredging Operations Technical Support Program

It. CONTROLLING OFFICE NAME AND AODRESS I2. REPORT DATE

October 1983

Water Resources Support Center 13.NUMBEROFPAGES

Fort Belvoir, Va. 22060 421

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U. S. Army Engineer Waterways Experiment Station

Environraental Laboratory Unclassified

P. 0. Box 631, Vicksburg, Miss. 39180 IS-. OECLASSIFICATION/DOWNGAAOINO

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

Springfield, Va. 22161.

IS. KEY WORDS (Co.the nM . ,yo old. I f --ce07 -W, ld-.dl4y &Y blOCk o•bt"¢)

Dredging

Marine deposits

Sedimentation

Toxicology

MG AIRSTIRACT re.-I -M i f,.7Rdhidwi1 -. ar5, block -,b-)

,> The 7th U. S./Japan Meeting on Management of Bottom Sediments Containing Toxic Substances was held 2-4 November 1981 in New York City. f The

meeting is held annually through an agreement with the U. S. Environmental7

Protection Agency 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.

DO I 'C 13 eno* or I NOV3 IS OBSOLET. Unclassified

SECURITY CLASSIFICATION OF ThIS PAGE (,, 0.1. EnI.,.)

Il
I

PREFACE

The 7th U. S./Japan Heeting on Management of Bottom Sediments Containing

Toxic Substances was held 2-4 November 1981 in New York City. The meeting

is held annually through an agreement with the U. S. Eavironmental Protection

Agency (EPA) 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.

Topics of the presentations and discussions at the recent meeting have

been more closely related to the Corps' dredging and regulatory missions than

to EPA's mission. At the request of EPA, MG E. R. deiberg III, Director of

Civil Works, agreed for the Corps to become the lead agency' for the meetings.

HG Heiberg appointed COL Haximilian Imhoff, Commander and Director of the

Water Resources Support Center (WRSC), as the U. S. Chaiman.

Assistance in coordination of the organizational activities and publication of this report was provided by Hr. Thomas R. Patin, program assistant,

and Hr. Charles C. Calhoun, Jr., Program Hanager, Dredging Operations Technical Support Program (DOTS), U. S. Army Engineer Waterways Experiment Station

(WES), Vicksburg, Hiss.

",•.ý,R •t r L. ta• 1. or/ _-. -- -..---

01i! J?
ATTENDEES

7th ANNUAL MEETINC

U. S./JAPAN EXPERTS MEETING

U. S. Delegation

COL Maximilian Imhoff, Cochairman CE, Commander and Director, Water Resources

Support Center (WRSC)

William Murden CE, Chief, Dredging Division, WRSC

Herbert R. 4aar Board of Commissioners of the Port of New Orleans

Charles C. Calhoun CE, Waterways Experiment Station

T. Allan Haliburton Haliburton and Associates

Robert H. Engler CE, Waterways Experiment Station

Thomas R. Patin CE, Waterways Experiment Station

David Mathis CE, Dredgizr Division, WRSC

Dennis Suskowski CE, New York District

Italo C. Carcich State of Neew York

Jim Tofflemire State of New York

Ron Vann CE, Norfolk District

Willis Pequegnat Texas AAM University

Ken Hall CE, Waterways Experiment Station

lack Bechly CE, Portland District

Japanese Delegation

Rikuro Takata, Cochairman Bureau of Ports and Harbours

Ministry of Transport (MOT)

Hiroaki Togashi Dredging and Reclamation Engineering

Association

Kiichi Kikegaiwa Dredging and .'ciamation Engineering

Association

Masakuni Nakamura Bottom Sediment Management Association

Masao Shimoda Bottom Sediment MAnagement Association

Hiroshi Kubo Bottom Sediment Management Association

Hiromi Koba Dredging and Reclamation Engineering

Association

Toyoaki Shiba Dredging and Reclamation Engineering

Association

Tadashi Otsuki Dredging ond Reclamation Engineering

Association

Mitsumasa Okada Environment Agency

Tatsuo Yoshida bottom Sediment Management Association

Ichiro Ofuji Wcrkvessel Association

Naoshi Ishimatsu Wo\-kvessel Association
CONTENTS

Page

PREFACE . I

ATTENDEES . . . . . . . . . . . . . . . . . . . . . . . . . ... . . .. 2

AGENDA . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . .. 5

JOINT COMMUNIQUE ........................... 8

CONVERSION FACTORS, U. S. CUSTOMARY TO METRIC (SI)

UNITS OF MEASUREMENT ..................... ................. ..... 9

PROSPECT OF SEA BOTTOM MANAGEMENT IN PORTS AND HARBORS

AND SEA WATER AREAS IN JAPAN by Rikuro Takata ................... 10

RESCUING THE PORTS by H. R. Haar, Jr ...... ................... ... 29

DESIGN AND CONSTRUCTION OF FABRIC-REINFORCED DREDGED MATERIAL

RETAINING DIKES by T. Allan Ifaliburton ............. .............. 39

SAND OVERLAYING FOR SEA BOTTOM SEDIMENT IMPROVEMENT BY

CONVEYOR BARGE by Hiroaki Togashi ............................... 59

SAND OVERLAYING FOR BOTTOM SEDIMENT IMPROVEMENT BY

SAND SPREADER by Kiichi Kikegawa ............................... 79

STUDIES ON CAPPING OF CONTAMINATED DREDGED MATERIAL IN

NEW ENGLAND DIVISION by R. C. Semonian ....... ............... ... 104

STUDIES, ON CAPPING OF CONTAMINATED DREDGED MATERIAL BY

THE NEW YORK DISTRICT, CORPS OF ENGINEERS

by D. J. Suszkowski . ........................................... 134

EXPERIENCES WITH THE STABILIZATION OF SEDIMENTS

by M. Nakamura ..... ............................... ... 146

PCB CLEANUP ACTIVITIES ON THE UPPER HUDSON RIVER

by I. G. Carcich and J. Tofflemire ......... ................. ... 168

PRODUCTIVE USE OF CALCINED SEDIMENT

(Calcination of Sediment for an Artificial Aggregate)

by Masao Shimoda . ........................................... 181

SEVERAL SOLIDIFIED SEDIMENT EXAMPLES

by D. Kita and H. Kubo ......................................... 194

JAMES RIVER, VIRGINIA DREDGING DEMONSTRATION IN

CONTAMINATED MATERIAL (KEPONE) DUSTPAN VERSUS CUTTERHEAD

by R. G. Vann .................. ............ ................ .. 211

TELT DREDGING ')F BOTTOM SEDIMENTS IN OSAKA BAY

by Hirými Kn!"s and Toyoaki Shiba ........... .................. ... 225

MA.N#.UEMENT TOOLS FOR ASSESSMEiNT OF DREDGED

MATERIAL IMPACTS by W. E. Pequegnat ............ ................. 252

PURIFICATION OF WATER AND SEDIMENTS USING ORGANISMS

(LIVING FILTER)--REMOVAL OF SUSPENDED SOLIDS AND

NUTRIENTS BY PHRAGMITES COMNUNIS T. AND ZOSTERA MARINA L.

by Tadashi Otsuki .............................................. 260

3

A
Page

THE EFFECTS OF NUTRIENT RELEASE FROM SEDIMENTS ON THE

FORMATION OF WATER BLOOMS by Mitsumasa Okada and

Ryuichi Sudo ....................... ............................ 281

SUhMER PEAK OF NUTRIENT CONCENTRATIONS IN LAKE WATER

by T. Yoshida ...................... ............................ .. 302

.1981 STArJS REPORT ON THE ENVIRONMENTAL AND WATER

QUAT!TY OPERATIONAL STUDIES PROGRAM by J. L. Mahloch and

K. G. Hall ....................... ............................. 320

MARINE TECHNOLOGY FOR ENVIRONMENTAL PROBLEMS

-Some Exampes of Improved Systems on Workvesselsby Ichiro Ofuji and Naoshi Ishimatsu ............................ 334

MOUNT ST. HELENS ERUPTION, CORPS OF ENGINEERS

RESTORATION EFFORTS by J. F. Bechly ......... ................. .. 367

THE WATER QUALITY PRESERVATION MEASURES IN LAKE BIWA

by M. Shirahase .................... ..................... ...... . 391

WATER POLLUTION CONTROL PROJECTS IN RIVERS AND LAKES

IN JAPAN by Kanenobu Hagiwara .............. .................... .. 407

4
AGENDA

7th U.S./JAPAN EXPERTS MEETING ON MANAGEMENT

OF BOTTOM SEDIMENTS CONTAINING

TOXIC SUBSTANCES

World TradeCenter

New York City

2-4 November 1981

Cochairmen

Mr. Rikuro Takata

Director, Environmental Protection Division*

Bureau of Ports and Harbours, Ministry of Transport

COL Maximiiian Imhoff

U. S. Army Corps of, Engineers, Water Resources Support Center

Monday, November 2, 1981

0800 Bus departs for World Trade Center

0830-0900 Opening session

0900-0930 Rikuro Takata, "Prospect of Sea Bottom Management in Ports

and Harbors and Sea Water Areas in Japan," Ministry of

Transport, Japan

0930-1000 Herbert R. Haar, "Rescuing the Ports," Board of Commissioners

of the Port of New Orleans, USA

1000-1030 Kanenobu Hagiwara and Masamichi Shirahase, "Water Pollution

Control Projects in Japanese Rivers and Lakes," Ministry

of Construction, Japan

1030-1100 T. Allan Haliburton, "Fabric Reinforced Dike Design and Construction," Haliburton and Associates, USA

1100-1300 Luncheon

1300-1330 Hiroaki Togashi, "Sand Overlaying for Sea Bottom Sediment

Improvement by Conveyor Barge," Dredging and Reclamation

Engineering Association, Japan

5!
1330-1400 Kiichi Kikegawa, "Sand Overlaying for Sea Bottom Sediment

Improvement by Sand Spreader," Dredging and Reclamation

Engineering Association, Japan

1400-1430 V. L. Andreliunas and Dick Semonian, "Studies on Capping of

Contaminated Dredged Material in New England Division,"

Corps of Engineers, USA

1430-1500 Dennis Suskowski, "Studies on Capping of Comtaminated Dredged

Material Conducted by New York District," Corps of

Engineers, USA

1500-1530 Masakuni Nakamura, "Experience on the Stabilization of Sediments," Bottom Sediment Management Association, Japan

1530-1600 Italo G. Carcich and Jim Tofflemire, "PCB Cleanup Activities

on the Upper Hudson River," State of New York, USA

1600-1630 Masao Shimoda, "On the Calcination of Sediment for an Artificial Aggregate," Bottom Sediment Management Association,

Japan

1630 Bus returns to Milford Plaza Hotel

1800 Bus departs for Seaman's Institute

1830-2030 U. S. Reception for Japanese delegation

2030 Bus departs for hotel

Tuesday, November 3, 1981

0800 Bus departs for World Trade Center

0830-0900 Hiroshi Kubo, "Several Solidifying Works of Sediment," Bottom

Sediment Management Association, Japan

0900-0930 Ron Vann, "Kepone Removal from the James River," Norfolk District, Corps of Engineers, USA

0930-1000 Hiromi Koba and Toyoaki Shiba, "Test Dredging of Bottom Sediments in Osaka Bay," Dredging and Reclamation Engineering

Association, Japan

1000-1030 Willis Pequegnat, "Biological Assessment Studies for Predictions of Cause and Effect Relationships," Texas A&M

University, USA

1030-1100 Tadashi Otsuki, "Purification of Water and Sediments Using

Organisms (Living Filter) - Removal of Suspended Sediment

and Nutrients," Dredging and Reclamation Engineering

Association, Japan

6
1100-1130 Mitsumasa Okada, "The Effect of Nutrient Release from Sedisent on the Formation of Water Blooms," Environment

Agency, Japan

1130-1200 Tatsuo Yoshida, "On the Summer Peak of Nutrient Concentrations in Lake Water, Bottom Sediment Management Association,

Japan

1200-1230 Ken Hall, "Overview of the Corps Environmental and Water 1 Quality Operational Studies," Waterways Experiment Station,

Corps of Engineers, USA

1230-1630 Harbor Tour (Luncheon to be served on board)

1630 Bus departs for hotel

Wednesday. November 4, 1981

0800 Bus departs for World Trade Center

0830-0900 Ichiro Ofuji and Naoshi Ishimatsu, "Marine Technology for

Environmental Problems - Some Examples of Improved Equipment on Workvessels," Workvessel Association, Japan

0900-0945 Jack Bechly, "Navigation Impacts of Mt. St. Helens Eruption,"

Portland District, Corps of Engineers, USA

0945-1200 Closing session

7

S-L

T!V
JOINT COW¶UNIQUE

The 7th U. S./Japan Experts Meeting on Management of Bottom Sediments

Containing Toxic Substances was held by the Japanese (Rikuro Takata, Director,

Environmental Protection Division, Bureau of Ports and Harbours, Ministry of

Transport) and the United States (COL Maximilian Imhoff, ComaanderJDirector,

Water Resources Support Center, U. S. Army Corps of Engineers) Co-chairmen

November 2-4, 1981, at New York, N. Y., U. S. A. The purpose of the conference was to exchange information in both regulatory and technical areas

relevant to bottom sediments management and to explore areas where joint effort

in the dredging and marine technology fields would be fruitful.

Japaneze and United States experts presented papers on several technical

and managerial subjects including: prospects of sea bottom management and

water pollution control administration in Japan, four studies of subaqueous

sand overlaying and capping of contaminated dredged material deposits, experience on the stabilization of sediments, PCB cleanup activities on the upper

Hudson River, Kepone removal from the James River, an overview of efforts by

port and harbor associations to resolve iegulatory 'roblems confronting their

industry, fabric-reinforced dike design and constru'tion, summer peak of nutrient concentrati ns in lake water and effects of ediment nutrient release

on water bloom formations, feasibility of sediment calcination for artificial

aggregates, several solidifying works of sediments, test dredging of bottom

sediments in Osaka Bay, purification of water and seliments using organisms,

management tools for assessing dredged material impacts, improved marine technology for environmental problems, navigation impacts of the Mt. St. Helens

eruption, an overview of the Corps' environmental and water quality operational studies, and advances in dredging technology, to include new equipment

and operational techniques.

The attendees represented a broad spectrum of engineering and scientific

disciplines. Technical papers were presented by representatives of the Federal Government cf Japan and the United States, from States, universities,

Port Authority, engineerinR firms, and from other industrial interests.

There was generAl agreement that this conference has been highly fruitful in meeting its major goal: to exchange th,' mcst recent information in

techniques management and the ervironmental uffects of sediment material containing toxics and other pollutants. Consistent with the pruvisions of the

Memorandum of Understanding, the next meeting should be held in Japan and the

dates will be decided jointly by the Co-chairmen.

Director, Environmental Commander/Director, Water Resources

Protection Division, Bureau Support Center, U. S. Army Corps

of Ports and Harbours, of Engineers

Ministry of Transport

Rikuro Takata : OL Maximiliam Imhoff //

November 4, 1981 November 4, 1981

8
CONVERSION FACTORS, U. S. CUSTOMARY TO HMtIC (l11

UNITS OF NEASUREMNT

U. S. customary units of measurement used in this report can be converted

to metric (SI) units as follows:

Multiply BY To Obtain

acres 4046.873 square meters

cubic yards 0.7645549 cubic meters

feet 0.3048 meters

gallons per day per 40.75 cubic decimeters per day

square foot per square meter

gallons (U. S. liquid) 3.785412 cubic decimeters

horsepower (550 foot- 745.6999 watts

pounds per second)

inches 25.4 millimeters

miles (U. S. statute) 1.609347 kilometers

million gallons per day 1.54723 cubic feet per second

pounds (force) per square 47.88026 pascal*

foot

pounds (force) per square 6894.757 pascal$

inch

pounds (mass) 0.4535924 41 lograms

tons (2,000 lb, mass) 907.1847 kilogram

9

ii
AD P 00239 2

PROSPECT OF SEA BOTTOM MANAGEENT

IN PORTS AND HARBORS AND SEA WATER AREAS

IN JAPAN

Rikuro Takata

Director,

Environmental Protection Division

Ports and Harbors Bureat,

Ministry of Transport

Kasumigaseki 2-1-3, Chiyoda-ku

Tokyo, Japan, 100

ABSTRAC'I

The Bureau of Ports and Harbors, Ministry of

Transport, has undertaken two projects that relate

to sea bottom management. The Marine Environment

Improvement Pilot Project is an experiment to clean

organic bottom sediment accumulated in the closed inland bays and inland waters, and the Port Pollution

Control Works is a project to clean polluted bottoms

in the port areas. This paper introduces the prospect

of these two projects in relation to the 6th Five-Year

Plan for Port Improvement Program (period from 1981 to

1985)."

INTRODUCTION

Since the 1960's, Japan's economy has experieiced a rapid growth that

lacked environmental protection and sufficient measures for prevention of pollution. Because of this, environmental pollution has occurred, causing -rave

social concern. In the 1970's, various laws were revised and enacted, including the revision of Basic Law for Environmental Pollution Control; our

system of environmental measures has also been organized.

For ports and harbors, a section of the Port and Harbor Law and Public

Water Area Reclamation Law was revised in 1973 and judicial measures were established for the environmental protection of ports and harbors.

Presently, sea bottom management is undertaken as a part of the

10
Improvement Works of Port Facilities (with government financing such as Marine

Environment protection pilot work of Tokyo Bay, Ise Bay, and Seto Inland Sea)

and the Port Pollution Control Works in port areas.

The former is carried out as experimental work for studying and developing the efficient and economic methods and grasping the improvement effect of

water quality by sea bottom management for improving enclosed environments

such as inland bays and inland waters. The latter carries out dredging and

"sand overlaying of the sea bottom in ports and harbors where the livelihood of

the population in the area is affected by the deteriorated water quality and

bad smells caused by organic bottom sediment or harmful substances.

MARINE ENVIRONMENT IMPROVEMENT PILOT PROJECT

The Marine Environment Improvement Pilot Project is to carry out sea bottom management by the Port and Harbor Bureau of the Transportation Ministry on

especially polluted waters as a model case to assess the effect of the management on the enclosed inland bay and inland waters and to establish the method

of work.

The work, now at the Practical Design Study stage, is being. carried out

on Tokyo Bay, Seto Inland Sea, and Ise Bay to study a wide range of actual

pollution conditions; to study environmental improvement assessment, test work,

and field investigation of the effect; and to study the work method.

The future program of the Marine Environment Improvement Pilot Project is

discussed below.

Need for Sea Bottom Mnangement

Environmental Problems on Inland Bays and Inland Seas

Figure I shows the pollution load history in the Seto Inland Sea, and

Table I shows the pollution load history in Tokyo Bay. Both indices show

rapid increases in the 1960's. In 1970, a water pollution prevention, law was

enacted leading to the establishment of effluent standards at factories and

businesses; further standards were crested in many places by local regulations.

In the Seto Inland Sea, Ise Bay, and Tokyo Bay, total restriction of COD

was enforced. As a result, the inflow load of COD in Tokyo Bay and Seto Inland Sea has decreased to the level of around 1955 (Figure 1, Table 1).

TABLE 1. COD INFLOW LOAD IN TOKYO BAY

Year 1955 1971 .1976

COD, t/day 500 1,200 300

•, 11
=coo Infl ow Lowd (taet))

COO Inflow Load

(For factory only)

Wtday) coo (P"m)

Enforcumnt of Mator Pollutiou

Control Law

3000--.0 2 8/

3 SE

I .

/

00.0

lss '6 166 '70 1S 0.0

Figure 1. Yearly changes of COD inflow load into Seto Inland Sea

Although the inflow load of COD has decreased remarkably, water quality

has not improved as expected and stays at the same *level as '75 (Figure 1).

One of the reasons may be the elution of nutrient salts from the bottom sediment deposited in the past. The mechanism of circulation of substances (mechanism of eutrophication) that causes ill effects on the environment of the sea

needs to be studied.

Mechanism of Eutrophication

Figure 2 shows a model of the circulation of substances in seawater. Inflow from the land and elution of the sea bottom are the sources of inorganic

nutrient salts that generate red tide and eutrorhication.

In Tokyo Bay, Seto Inland Sea, and Ise Bay, poll.ating substances discharged over a long period of time have widely accumulated on the sea bottom,

creating a loss of oxygen in water. This loss is due to the dissolution of organic substances in bottom sediment and the elution of large amounts of nutrient salts from bottom sediment and production of the large amount of organic

substances in the bay. Therein lies one of the reasons why water quality does

not improve despite the reduction of inflow load of COD. In such waters, to

improve the marine environment, it is necessary to stop the cycle of sea pollution by managing the sea bottom together with reducing the inflow load of COD,

H, and P.

12

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tn

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004

13
This is substantiated by the fact that the water quality of part of the

Seto Inland Sea (Osaka Bay, the sea of Hariaa, Hiroshima Bay, and the sea of

Suoo and Beppu Bay) is poor due to organic bottom sediment.

Environmental Improvement by Sea Bottom Management

The effect of sea bottom management field-testing work is shown from the

results of a study in ?ikawa Bay.

By removing the bottom sediment of an area 100 a x 100 a x 1G cm thick,

remarkable improve"ents have been observed on the eluted mount of nutrient

salts and benthos. This study has proved that sea bottom management is an effective means to improve the marine environment (Figure 3).

22 183 (g) 8.6

No. of No. of Wet

types indi- weight

15 100 vlduals 4

3

10

50 2

5

(Legend)

of , .• -1 0 i , - 1 0 4 t

4) I-.

(Note) Each index shows a value per 30 square ca.

CL5.

Figure 3. Improvement effects of living things on

the sea bottom

By using the reduction rate of nutrient salts (phosphorus) elution, the

effect of removal of more than 30 mg/g(COD) of the bottom sediment in the

Mikawa Bay is calculated to be equivalent to 33% of T-P flowed in from the

rivers.

14
Purpose of Marine Environment Improvement Pilot Project

In order to remove a large deposit of sludge accumulated widely over an

enclosed inland bay and inland waters:

1) A sea bottom management program must be established to effectively improve the marine environment.

2) Dredging and overlaying must be conducted in waters where there is

heavy ship traffic and where good fishing ground is located.

3) A thorough study must be made on the method of disposing the dredged

material that contains a large amount of sludge.

For this reason, before undertaking the actual sea bottom management work,

pilot work must be done and the effect and method of sea bottom management

must be established. In this connection, the Marine Environment Improvement

Pilot Project is carried out in areas where the sea bottom is heavily polluted. At the stage of Practical Design Study of the pilot work, actual conditions of pollution and factors of the cycle of substances are obtained and

the effect of water quality improvement is studied by simulation of these

figures. A preliminary study is also undertaken on the method of work.

Pilot work is carried out on a broader range after results of the Practical Design Study are obtained. The effect of improvement of water quality

is confirmed in the field and the method of sea bottom management suited to

the subject waters is established.

Outline of Marine Environment Improvement Pilot Project

In the Marine Environment Improvement Pilot Project the environmental improvement effects by sea bottom management are established and the sea bottom

management work method, studies, test work, and technical development are carried out considering the characteristics of each subject water with the system

shown in Figure 4 as the standard.

Subject waters for the Marine Environment Improvement Pilot Project included the Seto Inland Waters (Osaka Bay, Hiroshima Bay, and Suoo Sea), Ise

Bay, and Tokyo Bay. Table 2 shows characteristics of the subject waters, and

Table 3 outlines the work.

The Pilot Project will be conducted for 4-5 years after making the Practical Design Study in each waters and establishing the effects of sea bottom

management and the work method in the inland bays and waters. Table 4 and Figure 5 show the work program for Tokyo Bay.

PORT POLLUTION CONTROL WORKS

Outline of the System

The Port Pollution Control Works carries out dredging of bottom sediment

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20

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and overlaying of earth or installation of water line and other port and harbor pollution control facilities where sludge and other pollutants are deposited or where water is polluted in ports and harbors. The work is 50 percent subsidized by the government fund and as sub-government work pursuant to

Art. 3 of the L~w Concerning Special Government Financial Measures for Pollution Control Project and Art. 43 of the Port and Harbor Law.

Work related to the disposal of bottom sediment is carried out in accordance with the former law. In order to qualify under the law, an environmental pollution control program, pursuant to Art. 19, para. 2, of the Basic

Law for Environmental Pollution Control, is prepared as designated by the

Minister of Hoae Affairs in consultation with the minister in charge and the

Minister of Environmental Agency, pursuant to Art. 3, pars. 3, of the Law

Concerning Special Government Financial Measures for Pollution Control

Project.. The des'anat:on is made for each single year.

In cases where hasinesses caused the pollutions, Art. 4 of the Law concerning Entrepreneurs' Bearing of the Cost of Public Pollution Control Works

requires the business to withstand all or part of the cost required for the

work depending on the extent of the cause acknowledged as pollutant.

The Port Pollution Control Works has been carried out as part of the Improvement Works of Port Facilities since '72.

Work Program for 1981

Table 5 shows the work cost and amount of dredged soil of the Port Pollution Control Works for 1981 now under way.

TABIE 5. WORK PROGRAM OF PORT POLLUTION CONTROL WORKS IN 1981

Cost of Work (million yen)

Name of Port (Government Expense) J uantity (100Mn3 )

Tokyo 1,220 (610 ) 174.9

Yokohama 138 ( 68 ) 82.8 2

Nagoya* 411 (74.089) ( 16.2 lOOOm2)

Tsu-Matsuzaka 600 (300 ) 101.5

Osaka 727 (363.5 ) 195.5

4imeji 320 (160 ) 30.7

Amagasaki-Nishino 224 (112 ) 52.9

miya-Ashiyz

Higashiharima 30 ( 15 ) 2

Omuta* 120 (12.426) ( 21.6 1000m

Minamata 4,026 (919.585) 266.7

TOTAL 7,814 (2,634.6) 916 (37.8)

The •mount of dredged soil at Nagoya and Omuta shows areas of

soil overlay.

21

I'
Future Program of the Work

Table 6 sho•a an overall program of Port Pollution Control Works (bottom sediment disposal); wnrk completed by '80; program of '81-85; program

after '86; and polluted substances, removal standards, etc.

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AD P002 393

RESCUING THE PORTS

H. R. Haar, Jr.

Board of Commissioners of the Port of New Orleans

P. 0. Box 60046, 2 Canal Street

New Orleans, Louisiana 70160

ABSTRACT

-,The environmental movement in the United States

of the early and mid-seventies 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 dredged material disposal permits, denial

of permits, delayed capital investment improvements,

increased investment and operation and maintenance

costs, and lost revenues. To counter these impacts

and to seek state-of-the-art 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 Urited States legislation and international convention. Decisions governing

ports and port operations engaged in international

trade must be made in the overall public interest and

welfare and not excessively hampered by environmental

considerations alone. Achieving organizational goals

will require continued effort, organizational funding,

and exploitation of opportunities to tell the story.

INTRODUCTION

Dredging and disposal of dredged material are essential operations in

maintaining the navigability and economic vitality of ports throughout the

world. In the United States, more than 350 million cubic yards* of dredged

material per year is dredged from more than 100 ports serving the nation.

*A table of factors for converting U. S. customary units of measurement to

metric (SI) is presented on page

29
More often than not, viable disposal options are limited, and ocean disposal of this material becomes the most economical alternative, the least damaging

to the environment, and the only practical method of disposal.

One example of the importance of ocean disposal of dredged material to

ports and the national economy--and one with which I am most closely associated--is the situation in the Lower Mississippi River. Maintenance of the

deep-draft navigation channels in 1978 at the Mississippi River-Gulf Outlet

accounted for 6.1 million cubic yards of dredged material disposed of in the

ocean. Waterborne commerce in the stretch of river from Baton Rouge to

below New Orleans, a distance of slightly more than 200 miles, totaled 572

million tons in 1978, making this one of the largest port areas in the world.

Ocean disposal of dredged material is the only feasible method of keeping

this vital shipping area open.

DISPOSAL OPERATIONS AND ASSESSING THE ENVIRONMENT

in recent years, however, ocean disposal operations have come under

close environi.ental scrutiny. Many ports throughout the world, and partic- ularly those in the United States, have experienced increased difficulty in

obtaining th.z necessary government permits to accomplish the dredging

required for normal operation and maintenance activities as well as capital improvements. Periodic maintenance dredging is essential for operations at

seaports. Delays in performing this maintenance often mean lost revenues,

inc.'eased shipping costs, and lessened port efficiency. These impacts affect

the economic vitality of a port.

Environmental Legislation

The ports of the United States began feeling the pressures generated by

new environmental laws during the early and mid 70's. Mandates of the

National Environmental Policy Act of 1969, the Federal Water Pollution Con-.

trol Act of 1972; the Marine Protection, Research, and Sanctuaries Act of

1972; and other federal laws impacted expansively on the scope and complexity of the federal regulatory program over port and channel construction and.

operation and maintenance activities. The Administrator of the Environmental

Protection Agency (EPA), in conjunction with the Secretary of the Army, was

required to develop regulations controlling dredging and filling activities

in waters of the United States and adjacent wetlands and controlli~ng disposal of dredged material in ocean waters (ocean dumping). These activities require evaluation and assessment of probable impacts. on the marine environment, wildlife habitats, and, in general, the overall environment, including

the well-being of man.

Chemical analyses of materials to be dredged was required after the

regulations were promulgated in 1974 and 1975. Soon afterward, water column

chemistry was additionally required to prepare an assessment. The degree of testing accuracy was greatly increased when EPA published its "Quality Criteria for Water" in July of 1976. Costs and time required to obtain per- mit approval were increased considerably.

30
On January 11, 1977, the United States Environmental Protection Agency

t revised the "Ocean Dumping" regulations and criteria, requiring additional

testing of materials to be dredged. An interim test procedure called

"bioassay" was included. In a bioassay, marine organisms such as juvenile

shrimps, clams, worms, and fishes are exposed to sediments and water taken

from the site to be dredged. Organism survival is evaluated after 96 hr.

After 10 days, the tissues of certain surviving organisms are analyzed for

chemical content to provide an indication of potential for bioaccumulation.

On September 7, 1977, this bioassay test procedure became mandatory in evaluating ocean disposal of dredged material.

A Case Study--Port of Lake Charles and Calcasieu River

A classic example of lengthy delays caused by this new regulation was

soon to unfold. On November 22, 1977, the U. S. Army Corps of Engineers

notified Region VI, U. S. Environmental Protection Agency, of the intent to

perform maintenance dredging of the Gulf approach channel to the Calcasieu

River and its inland reach.

Considerable discussion developed over the need for bioassays because

of exclusions provided for in the regulations. On February 15, 1978, EPA

refused approval of the permit until receipt of bioassay results. Bioassays were then run by a contractor, but results indicated a potential for

acute toxicity for marine organisms in direct contact with the sediments.

The EPA again disapproved the disposal operations, and, thus, the dredging,

on July 3, 1978.

The "Ocean Dumping" regulations provide that, if the material proposed

for dumping does not meet the criteria, the District Engineer may determine

that no economically feasible alternative method or site is available and

so notifies EPA's Regional Administrator. The District Engineer submitted

a report of these findings to the Chief of Engineers on October 11, 1978,

and requested that he certify these facts to the Secretary of the Army and

request that the Secretary seek a waiver of the criteria from the Administrator. Additional supportive information was provided to the Office of

the Chief of Engineers, and the Secretary of the Army subsequently requested the waiver from the Administrator, EPA, on February 7, 1979. Again,

additional information was requested by EPA (this was the first waiver

request which they had received). On April 18, 1979, EPA granted a partial

waiver to Mile 10 for maintenance dredging. Eighteen months elapsed from

the time of the original request to granting of the partial waiver.

(Incidentially, it was not until January 7, 1981, that the Administrator of the EPA informed the Secretary of the Army that he granted unconditional approval for the disposal of the maintenance dredging material

into the ocean. In rendering his determination, he found that such dumping

would not cause undue degradation to the marine environment. A period of

over three years had elapsed!)

31
In summary, it is most interesting to note that, if this problem had not

ben resolved and alternative disposal sites had been required, the annual

mlintenance dredging costs would have escalated from $1.1 million to $62.9

illion versus annual project benefits of $21.0 million. It would have also

involved thousands of acres of new dredged material disposal areas.

ORGANIZING FOR SURVIVAL

'•"•,Ainerican-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.

Its establishment was recognition that the then existing AAPA Committee

9 ructures and ensuing resolutions were ineffective in moderating the trend

ward increasing environmental restrictions on dredging activities. Early

, goals were established. These goals included the identification and

cumentation of those laws, rules, regulations, agencies, procedures, and

agreements creating dredging problems. Targeted for study were concerns

o er mitigation, compensation, endangered species, bioassay test criteria,

1 cal costs, permit delays, and interagency agreements. Additionally, the

Cbmmittee was charged with developing recommended revisions to existing regu1l~tions and procedures that would provide needed relief as well as the necess~ry documentation to support those revisions. Finally, the new Committee

w]s 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.

International Association of Ports and Harbors

In early 1980, a similar committee to coordinate on the international

s~cene was established by the International Association of Ports and Harbors

(IAPH).

At the IAPH Executive Board Meeting ia Brisbane, Australia, in April, 1980, there was considerable discussion of the problems the United States

Sorts had been encountering in their attempts in recent years to dredge their

acilities. The Board recognized that those difficulties stemmed in a large

measure from the United States being party to the "Convention on the Prevenion of Marine Pollution by the Dumping of Wastes and Other Matter," negotited in London in November of 1972, and more commonly called the "Lonaon

umping Convention" (LDC). Further, the Board agreed that it would benefit

ihe IAPH membership to develop a better understanding of port dredging practices and the relationship of those practices to the terms of the LDC.

32

. /

. ~/ . J
The missions of the International Ad Hoc Dredging Committee were:

1. To review, report, advise, and submit recommendations on major

matters relating to seaport and inland port dredging and dredging equipment;

2. To meet with and coordinate with the LOC 3nd the Inter-Governmental

Maritime Consultative Organization (IMCO), 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 the state of the art;

6. To publish a brochure on sources of information and assistant. on

dredging techniques and types of equipment best suited for given situations.

WORKING TOWARD THE GOALS

These two committees, the Ad Hoc Dredging Committee of the IAPH and the

Ad Hoc Dredging Committee of the AAPA, have pushed forward in their efforts

to resolve regulatory problems confronting the industry and to seek, as well,

solutions that are environmentally ar.d economically sound. (The AAPA Committee was redesignated as the Special Dredging Task Force of Committee II:

Channels and Harbors, in September of 1980 after a decision by the AAPA

Coordinating Committee to establish a Special Projects Fund. The Special

Projects Fund is established and maintained by voluntary participation--funds

being solicited from AAPA members and other individuals or entities with similar interests. Funds thus received will be used solely for technical and

legal assistance for the ongoing work of the Special Dredging Task Force.)

Three meetings were held by the AAPA Ad Hoc Dredging Committee during

calendar year 1980. These were on March 19, 1980, at Washington, D. C.; on

August 25, 1980, at New Orleans, Louisiana; and on October 20, 198n, at

Norfolk, Virginia. In the course of these meetings, and in other frequent

contacts among Committee members, work in connection with the following Committee objectives and subjects was conducted:

On March 14, 1980, AAPA representatives appeared before the House Committee on Merchant Marine and Fisheries to deliver a supporting statement on

H. R. 6361, entitled "A Bill to Amend the Marine Protection, Research and

Sanctuaries Act of 1972 In Order to Suspend Temporarily the Use of Bioaccumulation and Biomagnification Testings in the Evaluation of Applications

Relating to Ocean Dumping of Dredged Material, and for Other Purposes." The

testimony document for this hearing was forty-seven pages long and included

fifty pages of enclosures.

33
As a result of this hearing, action was taken to

develop proposed amendments to the Marine Protection,

Research, and Sanctuaries Act of 1972. These amendments, which would resolve many dredging problems,

were provided to several U. S. Representatives who

promised to co-sponsor the necessary legislation.

Through a meeting on March 19, 1980, with White House authorities of the

Carter Administration, the Committee and the AAPA at large derived substantial benefits and positive direction. The meeting included AAPA leadership

members and was held to provide an opportunity for discussing dredging problems. The group, including myself as the AAPA Special Dredging Task Force

Chairman, met with Mr. William G. Simpson, Deputy Assistant to the President;

and Mr. David M. Rubenstein, an Assistant to Mr. Stuart E. Eizenstat, Assistant to the President for Domestic Affairs and Policy. Our appeal for support

in dredging activities was delivered. We were cautioned that budgets were

being cut. Mr. Simpson later advised us that we needed to make stronger and

more frequent representations to Congress and involved government agencies.

The members of the AAPA Special Dredging Task Force believed that the

AAPA could provide influence on ocean dumping controls if the AAPA became invoived in the United States EPA-chaired Committee on Ocean Dumping, a Subcommittee of the U. S. State Department Shipping Coordinating Committee. This

Subcommittee was formed in 1976 to provide an opportunity fcr public and

government interagency comments and advice on United States policy relating

to the London Ocean Dumping Convention. As Chairman of AAPA's newly organized Dredging Committee, I requested in June, 1979, that the EPA appoint me

as a member of the Committee on Ocean Dumping, also frequently referred to

as the "Advisory Committee on Ocean Dumping." The appointment was finalized

on August 15, 1979.

During 1980, it became apparent that the EPA-chaired Committee on Ocean

Dumping was dominated by the outlook of the parent agency and sometimes

unfounded concerns of environmental organizations and, thus, would not provide

the vehicle to influence ocean dumping criteria so as to enhance dredging

programs clearly in the national interest. A direct appeal to the London

Convention aipeared to be the only hope. This was achieved through the

cooperation and assistance of Mr. Anthony J. Tozzoli, Port Authority of New

York and New Jersey, who is a Vice President of the International Association

of Ports and Hav*Uors and, at the time, was also Chairman of that organization's Dredging Committee. Through him it was possible to arrange for the

AAPA Dredging Task Force Chairman, who is also a member of the IAPH Dredging

Committee, to head an IAPH delegation with observer status at the 1980 Fifth

Consultative Meeting of the Contracting Parties to the London Dumping Convention held in London, September 22-25, 1980. This convention is the major

global treaty governing the ocean dumping of wastes, including dredged materials. It should be noted that as a signatory to this convention, the

United States is bound by the international rules and criteria in promulgation of national laws and regulations.

34
In appearing before the London Convention, the Chairman of our Dredging

Task Force presented a position paper directing the attention of the Contractina Parties to possible interpretations of the terms of the LDC and their

subsequent application to ocean disposal operations of dredged material. Application of differing interpretation could result in an absolute prohibition

of ocean dumping of dredged material--even when there may be no feasible or

practic.l alternative means of disposal, and even when the disposal might be

safely carried out if special care is taken. This, it was poited out, could

threaten world ports with closures resulting in devastating economic impacts

upon the flow of international commerce. IAPH urged the Contracting Parties

to consider these possible effects upon port operations. The IAPH also proposed a study on the dredged material issue with a view toward adopting whatever changes are needed in the LOC to ensure that there will be no unintended

or unnecessary interference with essential port operations.

The concerns expressed by the IAPH delegation at the Fifth Consultative

Meeting were well received. The Contracting Parties recognized the significance of the technical issues raised by the IAPH, namely, the use of

"special care" in the ocean dumping of dredged material. The consultative

parties directed that these issues be considered by the Ad Hoc Scientific

Group of the Convention at its next intersessional meeting of May, 1981, and

to report to the Convention at the Sixth Consultative Meeting to be held in

London in October, 1.981. The Contracting Parties also agreed to consider

during the intersessional period administrative/legal issues raised by !APH

as they relate to the application of the Convention and to submit any comments at the Sixth Consultative Meeting of the LDC.

IAPH employed a technical consultant in the environmental field, Dr.

Willis W. Pequegnat, an oceanographer for Texas A & M University, to develop

on a priority basis a technical paper for presentation to the internatitnal

Ad Hoc Scientific Group. The paper focused upon the "special care" measures

raised by the IAPH delegation during the Fifth Consultative Meeting. Dr.

Pequegnat advanced the basic premise that ways must be found to permit ports

and harbors to continue the dredging of new and existing waterways to ensure

the safe passage of conwrd.rcial shipping. He outlined a number of techniques

(clean material capping, borrow pit disposal, split-side disposal, deep

ocean disposal, hypersaline basin disposal, submarine canyon disposal, and

erection of offshore islands) for the disposal in the marine environment of

dredged material containing Annex I substances under the London Dumping

Convention.

Ad Hoc Scientific Group Report on Dredged Material (Paraphrase)

As a result of the Ad Hrc Scientific Group's considering the IAPH document at its intersessional reting in May of this year in Halifax, Canada,

the Group rendered a report to the Convention.

There was general agreement that, while many of the special measures

showed promise for future use, there is at present very little information

on the extent to which the techniques will be successful in practice. The

35
Ad Hoc Scientific Group, therefore, agreed that dredged material (spoil)

disposal operations involving special care techniques should be conducted

as field research studies to gather experience with a view to allowing "special care" measures to be used on a routine basis.

The Ad Hoc Scientific Group agreed that existing

regulations or the interpretation of the terms "trace

contaminants" or "rapidly rendered harmless" in

respect to Annex I contamination of dredged spoil

could be interpreted to allow national authorities to

eval'ate research results and utilize, as appropriate, ""special care" measures in the disposal of dredged spoil. These measures should ensure that disposal

was conducted in a manner which would avoid undesirable effects, especially the possibility of acute or

chronic toxic effects on marine organisms or human

health whether or not arisin(- from bioaccumulation in

marine organisms, and especially in food species.

The Ad Hoc Scientific Group, therefore, recommended to the Consultative Meeting that Contracting Parties should take note of the possibility of using

"special care" methods as suggested by the IAPH where

disposal of dredged spoil contaminated by Annex I

substances is being considered. The Group also recommended that Contracting Parties should be invited to

submit details of any experience gained, with respect

to using these methods, to future meetings of the Ad

Hoc Scientific Group.

The significance of the issues raised is highlighted not only by the

attention that will be given by the Contracting Parties, but also by the

inquiry received from Mr. P. A. Haywoo6, Secretary of the OSLO Comnission

(which administers the OSLO Convention, governing the ocean dumping of

wastes, including dredged material, in the North Sea). Mr. Haywood attended the Fifth Consultative Meeting in London as an observer for the OSLO

Conmnission and has expressed great interest in the IAPH position. He has

asked that the IAPH furnish him a copy of any statements which have been

prepared addressing these concerns, as well as any studies which may be

available (or which may be prepared) by the IAPH concerning the ocean

dumping of dredged material.

At the Sixth Consultative Meeting In London, IAPH additionally invited

the Contracting Parties to express their views upon the applicability of the "emergency" provisions of the Convention to the disposal of dredged material

containing Annex I substances which may not be within the "trace contaminant"

and "rapidly rendered harmless" exception provisions to Annex I materials.

On the issue of "special care" measures. we received support from the Contracting parties by the acceptance of the recommendations of the Ad Hoc Scientific Group. At the same time, the IAPH confirmed its continuing interest in

36
the consideration of "special care" measures at future meetings of Contracting Parties and the Ad Hoc Scientific Group and extended a continuing offer

of technical expertise in matters relating to dredged material. With regard

to utilizing the "emergency" provisions of the Convention, the delegates expressed a decided preference for using one of the "special care" techniques

proposed by the IAPH rather than consider the matter under the "emergency" !• clause.

Also, while in London for the Consultative Meeting, members of the IAPH

delegation met with members of the International Association of Dredging

Contractors to initiate a cooperative joint effort in the previously mentioned dredge equipment survey and capabilities studies.

Continued cooperation between the AAPA Dredging Task Force and the IAPH

Ad Hoc Dredging Committee is mutually beneficial and will serve to intensify

the efforts of both associations. Our Dredging Task Force cooperated with

the IAPH Committee in developing questionnaires for all ports, worldwide.

These questionnaires were designed to determine the effect of national and

international legal and regulatory controls on dredging efficiency. The

final report, "A Survey of World Port Practices in the Ocean Disposal of

Dredged Material as Related to The London Dumping Convention," was published

in April, 1981.

In the past presidential election year, advantage was taken to influence

the platform of the Republican Party by drafting a "plank" for a dredging

position. This position emphasized the problems inherent in current laws

and reguldtions and the need to include economic factors as a prime consideration in the implementation of such laws and regulations. The plank

emphasized that ports of this country were experiencing increased difficulties and delays--in some cases outright denials--in obtaining critically needed dredging permits necessary to provide adequate channels and harbors.

We are hopeful that presentation and recognition of our plank will gain

support and ultimately result in a critical reappraisal of and reforms in

the permitting and environmental approaches that federal regulatory agencies

have pursued with regard to dredging and disposal activities.

The Port Authority of New York and New Jersey provided an organizational model for pursuing a reasonable balance between economic and environmental values in the disposal of dredged material in their "Save Our Port"

activities and promotion. This program, largely through the energy of the

New Jersey Alliance for Action, an effective business and labor organization, brought a groundswell of concern for the port's dredging problem and

its effect on the community. This concern and the attendant activity

resulted in needed permit approvals from Washington. This model can serve

other port3 in trouble; however, we hope to resolve or ameliorate the problem before this is necessary.

Experience has shown that an inordinate proportion of delays in

granting aredging permits stems from a lack or delay in the "Interagency

Coordination Act of 1981" which would expedite agency action (particularly

37
in the area of environmental review) and would require action by each agency

in a reasonable period of time. This draft will be utilized to obtain input

and review by AAPA Standing Committees before approaching a Congressional

delegation to sponsor the legislation. Introduction and enactment of such

a law will do much to enhance the necessary ongoing dredging programs to

maintain and improve channels and harbors.

On December 24, 1980, the United States Eivironmental Protection Agency

published in the Federal Register as final rule-making the Section 404(b)(1)

Guidelines for Specification of Disposal Sites and Dredged or Fill Material

under Section 404 of the Clean Water Act. These guidelines failed to incorporate AAPA views which had been submitted earlier. The guidelines continue

to contain provision for prohibiting a discharge of dredged material or fill

material without regard to the total impact on the overall public interest.

The 404(b)(1) testing requirements were also published in the 24th of December

issue of the Federal Register. This rule-making required all comments to be

submitted on or before February 6, 1981. Our Dredging Task Force Committee,

in coordination with the AAPA Environmental Affairs Committee, did prepare

and submit AAPA comments.

On the basis of a projected work program for eighteen months, the Task

Force Chairman submitted to AAPA in the fall of 1980 an annual budget of

approximately $155,000 to fund technical and legal assistance to the Task

Force. The membership at large approved AAPA offices in Washington to raise

these funds by an appeal for donations and for AAPA offices to administer

the funds for the Task Force as required. Over $200,000 to date has been

made available for this worK. IAPH Headquarters in Tokyo is now in the process of soliciting funds fromu their multination membership to further this

program.

Summarizing 1981 to date, the Committee has continued to emphasize

direct liaison with concerned members of the Congress and officials of the

United States Army Corps of Engineers as well as other federal and state

agencies and officials with an interest in or control of dredging laws and

regulations. We are actively seeking the opportunity for any forum at which

we can present our problems and suggest the changes in procedures and

testing that are necessary. We have been successful in publishing our position in magazines read by the dredging, business, and port industries and

have been able to attend and participate in meetings and conventions representing elements in a position to influence our objectives.

We look forward to an even more productive year in 1982.

38
DESIGN AND CONSTRUCTION OF FABRIC-REINFORCED

DREDGED MATERIAL RETAINING DIKES

by

T. Allan Haliburton

Haliburton Associates, Engineering Consultants

P.O. Box 1132

Stillwater, OK 74076 USA

INTRODUCTION

During the last decade, environmental and land-use constraints have

resulted in more emphasis on confined dredged material disposal, as opposed to unconfined disposal on land or in shallow water, especially when

fine-grained maintenance dredged material and any contaminated dredged

material is disposed. As a result, considerable effort has been directed

toward proper management of confined dredged material disposal areas,

including design, construction, operation, and maintenance of such facilities; dewatering, reclamation, and reuse of uncontaminated dredged material; and similar activities Ill. In the U. S., the majority of research

and development concerning proper confined disposal area operation and

management was accomplished by the U. S. Army Corps of Engineers during

1973-1978, under the Dredged Material Research Program (DMRP). Intormation developed under the DMRP was then implemented by Corps of Engineer

operating elements and other agencies, with consultive assistance from

the Corps' Dredging Operations Technical Support (DOTS) Program. Methods

and procedures described in this paper were developed by the author while

on special assignment to the DMRP, and field verification of the concepts

was conducted with DOTS Program support.

Before any dredged material may be confined, some sort of confinement system must be constructed. Whether confinement is on land or in

shallow water, earth embankments or retaining dikes are normally the most

cost-effective method of retaining :he dredged material. Assuming no

foundation problems, costs of obtaining a cubic yard of confined disposal

area storage capacity by perimeter diking in the southeastern U. S. are

on the order of $0.25-$0.35 (1979 dollars), with similar costs incurred

39
A

to provide additional future capacity by perimeter dike raising 121.

However, in many coastal onshore or shallow offshore locations,

extremely soft, weak foundation soils may be present, and considerable

difficulty, and thus expense, may be incurred in construction of satisfactory retaining dikes to desired containment elevations. In the past,

construction of retaining dikes on poor foundation, with consequent peri.

odic failure and escape of dredged material, was regarded as an undesirable event, but one simply inhereat in soft-ground construction of

retaiving dikes. However, in recent years with stricter constraints on

escape of confined dredged material, especially when contaminated sediments are involved, it is quite often necessary to provide a positive

assurance of constructabilIty for retaining !'fkes on extremely soft foundation, so that positive containment of dredged material can be achieved.

Use of engineering fabric, a permeable artificial fiber textile product

(also called geotechnical fabric, geotextile, and filter cloth), placed

between the soft foundation and the retaining dike, has been found to

facilitace successful dike construction in spite of unsatisfactory foundation conditions.

US3 OF ENGINEERING FABRIC IN RETAINING DIKE

CONSTRUCTION ON SOFT FOUNDATION

Conventional Retaining Dike Construction Alternatives

Normal dredged material retaining dike construction procedures are

simple and well defined, consisting of:

a. Clearing and other site preparation along the proposed

alignment,

b. Sequential placement of fill material in thin lifts followed

by compaction or semi-compaction, and

c. Upon reaching design height, final shaping and placement of

slope protection, if necessary.

For stable foundation conditions, no problems are encountered with such

construction methods. Hovever, when soft/weak foundation conditions

exist, the dike may fail during or after construction by horizontal

splitting, rotational slope/foundation failure, or excessive settlement.

40
For such adverse foundation conditions, alternative construction procedures must be used. Conventional alternatives used for embankment

construction on soft foundation include preloading/staged construction,

construction with lightweight fill materials, construction of floating

sections with stability berms, excavated and replaced embankment sections, and displacement embankment sections 13]. Advantages and disadvantages of these various soft ground construction alternatives are

listed in Table I. In general, engineeriag fabric-reinforced retaining

dike construction will be more cost-effective than any Table 1 alternative except preloading/staged construction, and that option is usually

operationally impractical because of disposal-related time constraints.

Fabric-Reinforced Retaining Dike Design

Concepts and Analysis

Earthfill embankments on soft foundation are susceptible to failure

from horizontal splitting/spreading, rotational slope/foundation failure,

and excessive foundation displacement. Engineering fabric used as reinforcement must resist these various actuating forces to achieve satisfactory performance. The key to successful fabric-reinforced construction

is development of moderate to high fabric tensile stresses at low fabric

strains. Fabric tensile forces resist failure actr'rting forces, and fabric tensile modulus controls vertical and horizontal displacements of the

reinforced embankment. Additional considerations include development of

sufflci~nt soil-fabric friction to transfer embankment loads to the

fabric as tensile forces, and use of construction procedures which will

develop fabric tensile forces at small strains.

Potential fabric-reinforced embankment failure modes are illustrated

in Figure 1. Analytical procedures for determining required fabric

strength and tensile modulus make use of conventional geotechnical engineering relationships for soil mass behavior, which include expressions

for fabric strength, and will be summarized in subsequent sections. More

detail on analytical procedures is available elsewhere [4]. In analysis

of a fabric-reinforced embankment, it is assumed that embankment height,

embankment fill material, and foundation strength are known, and that embankment side slopes may be adjusted as necessary to provide proper

41
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REOD - SOIL-FABRIC

REQ'D - FABRIC TENSILE MOVEMENT FRICTION TO RESIST

MODULUS TO CONTROL SLIDING

LATERAL SPREADING

(NOT ILLUSTRATED)

" FABRIC

tSOFT REO'D - FABRIC TENSILE FOUNDATION?

STRENGTH TO RESIST

SPLITTING

A. POTENTIAL EMBANKMENT FAILURE FROM

LATERAL EARTH PRESSURE

REO*D - FABRIC TENSILE

STRENGTH TO RESIST

ROTATIONAL FAILURE

AND FABRIC TENSILE

MODULUS TO RESIST

EXCESSIVE DEFORMATION 'MOVEMENT

/• -F ABRIC WE

FABRIC MUST SOFT

BE TORN FOR FONAON

FAILURE TO OCCUR FOUNDATION2

B. POTENTIAL EMBANKMENT ROTATIONAL

SLOPE/FOUNDATION FAILURE

REO'D - FABRIC TENSILE

MODULUS TO CONTROL

FOUNDATION DISPLACEMENT M,,W V

,MUD WAVE

FABRIC .SOFT

FOUNDATION7

C. POTENTIAL EMBANKMENT FAILURE FROM

EXCESSIVE DISPLACEMENT

Figure 1. Potential Failure Modes for Fabric-Reinforced Retaining

Dikes on Soft Foundation

43

&\ , 
/ /

stability. In general, fairly flat embankment slopes h6h on .v or

greater) will be necessary on extremely soft foundation soils.

Embankment Splitting/Spreading

Fabric-reinforced embankment splitting-type failures, as illustrated

in Figure la, may occur by fabric tensile failure, by fill material sliding off the fabric surface, and/or by excessive fabric elongation.

In order to resist tensile failure, fabric tensile strength in the

direction normal to the embankment alignment must exceed the maximum lateral earth pressure by an appropriate factor of safety, as given in

Equation 1:

TF FS (PA) = FS (0.5 YmH2 KA) (1)

where

TF - Minimum fabric tensile strength,

"FS - Desired factor of safety,

-PA- Lateral earth pressure per unit length of embankment,

Ym - Moist unit weight of embankment fill,

H - Embankment height, and,

KA - Fill material coefficient of active lateral earth pressure.

"In order to transfer lateral earth pressure to the fabric and prevent the

embankment sliding horizontally off the fabric, the minimum angle of soilfabric friction is given by:

*SF tan-l [2(FS)PA)/ymXH2 )] (2)

44
/

where

*SF - Minimum angle of soil-fabric friction,

X - Slope parameter (i.e., for 5h on lv slope, X - 5), and other

symbols are as defined previously.

If the required soil-fabric friction angle exceeds 30, embankment side

slopes should be flattened, as most engineering fabrics suitable for use

as embankment reinforcement possess a value of soil-fabric friction approximately equal to 300 if loose, sand-sized fill material is used [5].

Lateral spreading of the embankment may be held to an average of

approximately 5% by selecting a fabric with minimum tensile modulus

(secant through the 5% strain value) of 10 times the minimum required

fabric tensile strength or:

EF - lOTF (3)

F where

EF Minimum fabric tensile modulus.

Slope Stability Analysis

Rotational slope failure potential may be evaluated using any conventional limit equilibrium slope stability analysis method and adding

the strength of the fabric layer to the resisting forces opposing rotational sliding, as the fabric must be physically torn for the embankment

to slide (Figure lb). Because fabric has no flexural strength, it is

assumed to deform so as to lie on the incipient slip circle and be placed

in tension.

Stability analyses should initially be performed for the no-fabric

condition and a critical slip circle and minimum factor of safety obtained. Once the critical slip circle is determined, the resisting

moment from shear strength developed along the critical slip circle

45

.4 I. . r~/ * /
p

necessary to provide the desired factor of safety can be computed. If

the factor of safety without fabric is inadequate, additional resisting

moment can be computed and the minimum required fabric tensIle strength

*TFR can be determined by dividing the extra resisting momeun required

by the critical slip circle radius. This procedure was ver fied by

Risseeuw [6], and is Illustrated in Figure 2.

Excessive Center Line Displacement

/

Excessive center line displacement of fabric-reinforce embankments

can be controlled by use of fabric with minimum required tetsile strength

and modulus determined previously and use of' an outward-inw rd fill

placement scheme, to be described subsequently.

Selection of Proper Engineering Fabric

The minimum value of fabric tensile strength necessary for satisfactory performance is the larger of TF and TFR computed previously

while the minimum fabric tensile secant modulus is F., computed previously. These values, along with the minimum value of soil-fhbric friction OSF should be used to select an appropriate fabric. It should

be noted that both fabric tensile strength and tensile modulus are normally expressed in units of force/width, with the thickness dimension

neglected. Further, results of grab strength tests (ASTM D-1682) should

not be used as a measure of fabric tensile strength. Appropriate test

procedures for determining fabric tensile strength, tensile modulus, and

angle of soil-fabric friction have been developed by the author and are

available [7].

In addition to the tensile strength, tensile modulus, aid soilfabric friction requirements for the particular embankment cdnfiguration

desired, fabric should be chosen with appropriate survivability and field

workability properties, considering site conditions, type of embankment

fill to be used, and available construction equipment, following available criteria [4]. Selection of fabric with proper field workability

(fabric ability to support required construction operations) is of

46
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47
extreme importance if men and/or equipment cannot maintain mobility along

the proposed alignment.

FABRIC-REINFORCED EMBANKMENT CONSTRUCTION PROCEDURES

The importance of specifying proper construction procedures for

building fabric-reinforced embankments on soft foundation cannot be overemphasized, as the desired fabric behavior cannot be obtained without

specific sequential construction operations. The most important construction consideration is to use an outward-inward sequential fill

placement procedure, as shown in Figure 3. This sequence is necessary to

provide fabric anchorage at the embankment toes prior to placement of

center fill, and is exactly opposite the conventional procedure used for

no-fabric embankment construction on soft foundation.

Further, successful embankment construction is contingent upon une

of construction equipment which will not fail the fabric and foundation

during initial material placement. The author's personal preference is

to use small wide-track dozers with maximum 2.5- to 3.0-psi ground pressure during fill spreading operations. If desirable, fabric-reinforced

haul roads can be constructed along each outside toe for hauling fill to

the working face and, if properly designed and constructed, can carry

fully loaded 12- to 15-cu-yd tandem-axle dump trucks. If extremely

soft foundation conditions exist, insufficient to support the contractor's

workmen, construction may be facilitated by "working on the mud wave," a

construction procedure which uses fill placement techniques to develop,

trap, and push a small surface mud wave forward under the fabric, facilitating fabric placement and stretching operations. This procedure is described in detail elsewhere [4, 81.

In general, fabric is placed with the warp or machine direction

transverse to the embankment alignment, in continuous toe-to-toe strips.

Adjacent fill direction edges should be sewn together with high-strength

polypropylene or polyester thread, with a seam strength at least equal to

the fill direction tensile strength of the fabric. Locked-type stitching

should be used or else all seams should be 6ouble-sewn. Fabric overlapping

isdefinitely not recommended as an alternative to sewing.

48

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Construction of a "working table' on which to place fabric is usually an unnecessary and unwarranted expense. Selection of fabric with

proper survivability and workability properties for direct placement on

the foundation is normally a more cost-effective alternative, and will

provide similar perforaance. More detail concerning appropriate construction procedures is available elsewhere 14).

FIELD VERIFICATION OF FABRIC-REINFORCED RETAINING DIKE

DESIGN AND CONSTRUCTION CONCEPTS

The design and construction concepts described previously were verified by field construction of a fabric-reinforced dredged material retaining dike for the U. S. Army Engineer District, Mobile, at Pinto Pass,

Mobile Harbor, Alabama. The project was part of retaining dike construction necessary for development of the Pinto Island Disposal Area to contain maintenance dredging from Mobile Harbor. Concepts were verified by

construction of an 830-ft-long embankment test section, located as shown

in Figure 4. Foundation conditions along the proposed dike alignment

consisted of very soft clays and silty clays with moderate organic content and high plasticity, having undrained shear strengths of approximstely 50 psf at the surface, increasing to approximately 150 psf 40 ft

below the surface, where dense sand was %;:ountered. Approximately 50%

of the proposed test section alignment was in the intertid-! zone. A

typical cross section of the embankment, showing the sett*4peent plates

Installed at each 100-ft station, is Ahown !n Figure 5. in a&dditlon to

the settlement plates, eight Casagrande piezometers were installed at

various depths from 10 ft below the surface to 40 ft below the surface

to monitor foundation pore pressures.

Construction was initiated using low-ground-pressure dozer equipment

for material spreading and 12-cu-yd, tandem-axle dump trucks for fill

material transport, folloving the outward-inward material placement

sequence shown in Figure 3. Fine, poorly graded sand available from

Mobile Harbor new-work dredging activities wyes used as embankment fill.

Initially, a working table was constructed over the existing root mat

prior to fabric placement, but this operation was found to be unneeded

and to constitute an unnecessary expense; thus, the fabric was placed

50

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directly on the alignment for the remaining construction. Typical photographs of ongoing construction activities and the completed embankment

are shown in Figure 6. More detail on actual construction operations

is available elsewhere [8].

Typical foundation and settlement displacement behavior of the

fabric-reinforced embankment is shown in Figure 7 for Stations 5+00 and

6+00 in the center of the Pinto Pass channel. At these locations, construction operations caused a shallow surface mud wave to develop,

raising the fabric above the original ground elevation at the time embankment fill was applied. The "as-installed" fabric position imediately after placement of initial embankment fill and the after-foundation

settlement position of the fabric are shown at these two sections in

Figure 7. As may be noted from the figure, maximum consolidation settlements on the o-der of approximately 1.5 ft were noted. Original construction produced (essentially) a zero effective stress condition in the

foundation, with excess pore pressures approximately equal to the weight

of embankment fill. Approximately 7 months was necessary for 90%+ foundation consclidation to occur, and measured consolidation settlements were

approximately 20% of theoretically predicted values. Because the surface

mud wave that developed during construction raised the fabric above the

original ground elevations, the final fabric location after foundation consolidation was at or only slightly below the original ground surface, resulting in construction with minirum foundation displacement. In addition,

* the embankment underwent approximately 4 ft of lateral spreading as a result

of fabric elongation necessary to develop tensile stresses necessary to

resist unbalanced retaining dike lateral earth pressures.

Total project cost of the 800-ft test section was $154,000, including construction of fabric-reinforced roads to the adjacent borrow area.

A benefit-cost ratio of approximetely 2.3 was determined for the fabricreinforced construction, compared to foundation displacement construction, the alternative normally used by the U. S. Army Engineer District,

Mobile, for building retaining dikes on soft ground.

53
* If

A. View of Test Section Location, View

Looking West to East, Tracks Made

by Amphibious Vehicle

b. Embankment Fill Being Placed Over

Fabric Reinforcement

Figure 6. Photographs of Pinto Pass Fabric-Reinforced Dike Test Section

(Continued)

54
c. New Transverse Strip of Fabric Reinforcement Being Sewn in Place at

Working Face

d. Completed Dike, View Looking North to

South; Note Excess Foundation Pore

Pressure Seeping from Dike Side

Slopes

Figure 6. (Concluded)

55
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/-

CONCLUSION

/ 2 7 The design and construction concepts postulated for fabricreinforced retaining dike construction were successfully verified under

field conditions, and the method was fc~und to a technically feasible,

operationally practical, and cost-effective method of constructing

retaining dikes on an extremely soft foundation when positive assurance

of constructability is required.

Development of an overall management plan, including location and

design of dredged material retaining structures, is currently unter way

for the Pinto Island Disposal Area, and it is anticipated that fabricreinforced construction will be used for at least another 4,000 lin fit of

retaining dike at this location. A similar fabric-reinforced dike test

section is currently being designed for placement on very soft (undewatered) fine-grained dredged material in the Craney Island Disposal Area of

the U. S. Army Engineer District, Norfolk. Several other Corps of Engineer

operating elements are actively considering fabric-reinforced retaining dikes

as an alternative to their current dike construction procedures.

Use of the analysis technique, design methods, fabric selection criteria, and construction procedures summarized herein should allow qualified

engineers and contractors to build successful fabric-reinforced retaining

dikes for positive containment of disposed dredged material.--4ir-considering

use of fabric-reinforced dike construction alternatives, favorable benefitcost ratios will normally accure where existing foundation soil strengths are

low and when positive assurance of rapid construction is required.

I. 15
REFERENCES

1. "Guidelines for Designing, Operating, and Managing Dredged Material

Containment Areas," EM 1110-2-5006, Office, Chief of Engineers,

Department of the Army, Engineer Manual, 30 September 1980.

2. Haliburton, T. A., J. Fowler, and J. P. Langan, 'Perimeter Dike

Raising with Dewatered Fine-Grained Dredged Material at Upper

Polecat Bay Disposal Area, Mobile, Alabama," Miscellaneous Paper

78-3, Environmental Laborator), U. S. Army Engineer Waterways

Experiment Station, Vicksburg, MS, August, 1978.

3. Hammer, D. P., and E. D. Blackburn, "Design and Construction of

Retaining Dikes for Containment of Dredged Material," Technical

Report D-77-9, U. S. Army Engineer Waterways Experiment Station,

August, 1977.

4. Haliburton, T. A., J. Lawmaster, and V. McGuffey, "Use of Engineering Fabrics in Transportation Related Applications," Haliburton

Associates Report to Office of Development, Federal Highway

Administration, Washington, DC, Contract No. DTFH61-80-C-00094,

October, 1981.

5. Haliburton, T. A., J. Lawmaster, and J. King, "Potential Use of

Geotechnical Fabric in Airfield Runway Design," Report to U. S. Air

Force Office of Scientific Research, Contract No. AFOSR79-0087,

School of Civil Engineering, Oklahoma State University, Stillwater,

October, 1980.

6. Risseeuw, P., "Stabilenka Woven Reinforcement Fabric in Raising

Mounds on Soft Soil," Report No. R.O. 5300.005, Akzo Research

Laboratories, Department C.T.I., Arnhem, Holland, April, 1977.

7. Hal'iburton, T. A., C. Anglin, and J. Lawmaster, "Testing of Geotechnical Fabrics for Use as Reinforcement," Geotechnical Testing

Journal, American Society for Testing and Materials, Philadelphia,

PA, Vol. 1, No. 4, December, 1978, pp. 203-212.

8. Haliburton, T. A., J. Fnwler, and J. P. Langan, "Design and

Construction of Fabrir -Reinforced Embankment Test Section at Pinto

Pass, Mobile, Alabam:.," Transportation Research Record No. 749,

Transportation Rese rch Board, National Academy of Sciences,

Washington, DC, 1'80, pp. 27-34.

58
/ /

SoPO0239 5

SAND OVERLAYING FOR SEA BOTTOM SEDIMENT IMPROVEMENT BY CONVEYOR BARGE

Hiroaki Togashi

Japan Dredging and Reclamation Engineering Association

Toranomon-Kotohirakaikan Bldg, No. 2-8,

Toranomon 1-chome, Minato-ku, Tokyo, Japan

ABSTRACT

---- As a feasibility survey for a pilot project for

prevention of water pollution of the Seto Inland Sea,

the 3rd District Port Construction Bureau of the

SMinistry of Transport conducted a series of sand overlaying tests of sludge in an ar a off Kure in the

Hiroshima Bay in October 1979.z--

INTRODUCTION

Sand overlaying tests were intended to prevent harmful components from

dissolving out of the bottom sediment and into the seawater by laying 50 cm

of sand over the bottom sediment using a conveyor barge.

I>

The testing procedure and the test results are reported herein.

CONVEYOR BARGE

As illus rated in Figure 1, the conveyor barge has hoppers of a capacity

of about 110m arranged in two rows totaling 18 hoppers and also two lines

of belt conveyors 1,200mm wide running beneath each row of hoppers at a

"maximum speed of 125m/min. It thus has a capacity of discharging 2,000m of

sand in 1 hour and is different in performance from the conventional bottom

door type dumping barges in that the discharging capacity is adjustable over

a wide range up to 2,000m /hr, Without such a feature, this method of sand

overlaying would have been impossible.

This conveyor barge had a telescopic tremie tube provided at the bow,

and the length of the telescopic tube was adjusted according to the height

of the sea bottom so that the sand discharged from the tube would not disturb and spread the sludge as it hit the seawater.

59
t~ C12

0

z

L LA

I-MI I. 5JT

60
Originally, the conveyor barge was designed mainly for reclamation by

spreading, sand replacement work for revetment, improvement of sediment by

thin layer discharge, improvement of fishing fields by sand laying, and

transporting of sand, etc.

TEST SITE

The sand overlaying area was located between Etajima and Kure Port in

the Hiroshima Bay about 1km off Etajima Town (about 30 minutes by ferry from

Kure Port) and formed a rectangular of 120m north to south and 160kn east to

west.

!6

r:,

"" Hokkaido

Hi roshima

t

! Shikoku

K ushu

F S and Overlaying Kure Port

Area

Etajima 

1ndo

Figure 2. Test site

j 61
I '~/

THICKNESS AND VOLUME OF DESIGNED OVERLAY

With sand overlaid evenly in the design thickness of 50cm, the volume

of overlaying sand was planned as shown below:

Overlaying sand volume Area x (Design thickness + Maximum difference

in unevenness x 1/2)

where, Design thickness - 0.5m;

Maximum difference in unevenness 0.3m (empirical value); and

Area - 120m x 160m

lhus, Overlaying sand volume =120m x 160m x (0.5m

+ 0.3m x 1/2) 12,48Cm 3

TEST OF ADAPTABILITY OF OVERLAYING MATERIAL

The overlaying material was sea sand from Tadanoumi in Hiroshima prefecture, and it was tested physically, chemically, and biologically and for

harmful materials; as a result of these tests, it was found to be suitable. With an average specific gravity of 2.62 and silt content of 0.6 - 1.5%,

it was shell mixed, odorless, slightly yellowish, and weak alkaline sand.

$. WORK METHOD

The work method is shown below in Figure 3.

Middle Stage

Lower Stage

fell. C)

S Figure 3. Sand discharge by conveyor barge

Spread of the overlaying material was made in four cases (Cases 1, 2,

3 and 4) combining the spread times (1st and 2nd layers), the spread volume

(13M3 /min and 6.5m3/min), the swing speed (5m/min), and the falling position

(middle and lower stages). For particulars, see Figure 4 and Table T.

62

m4I
Each case had a test area and a work area, and the overlay found to be good

in the test area was then carried out in the work area.

160m

S_ 40m 40m _ 40o, 40m

Case 1 Case 2 Case 3 Case 4

Middle Lower Middle Lower

Legend

STest Area

ZWork Area

SMiddle Middle Stage

Spread

SLower Lower Stage Spread

Figure 4. Sand overlaying area

63
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64
SWING METHOD

STremie Tube

o 40m

P

Figure 5. Swing method

Referring to Figure 5, points a and a are positioned on the center

line of the spread width (40m), and (2Z) and Q) are on the extreme lines of

swing on the right and left har., sides, respe'-tively. In ov:r'laying, the

center of the tremie tube starts from point (D and completes a cycle of swing

at point 4 . That is, whenever a swing cycle is completed, the tremie tube

is returned to the center. Then, the barge moves back, and when the position

is determined, the tremie tube makes the next swing cycle. About 14 minutes

is required for the backward movement.

FULL SWING AND HALF SWING

Under a full swing, the tremie tube spreads sand successively from point

d• to point (D. Under a half swing, the tremie tube swings from point

to point 2() without spreading sand, spreads sand from point (2) to point%

and swings back to point • without spreading sand.

65
SURVEYS AND RESULTS OF SPREAD

After overlaying sand by the conveyor barge, data were collected and

analyzed to see if the overlaying material was penetrating into the bottom

sediment; if the sand was laid evenly over the sludge sediment; if the

planned thickness of overlay was secured; if there was any expansion of the

sand spread, diffusion of turbidity, stirring up of sludge, or unevenness in

the overlay; and what effect the current would have on diffusion of turbidity.

Further, the conditions after overlaying were photographed by a submarine IV

camera. The following items are discussed in this section:

(1) Survey of penetration

(2) Survey of stirring up of sludge

(3) Survey of settlement

(4) Survey of laps

(5) Survey of unevenness

(6) Survey of current

(7) Video picture taking

Survey of Penetration

A diagram of the penetration survey is given in Figure 6.

Marker Buoy k 3o

Overlay Sand • Acrylic Tube

SMaterial Thickness •..(For Core Sampl-

,4,

. • , :. :..:..-:'.: 'h,•** . . . ... :'... 

Bottom Sediment

Measuring

Instrumen Penetration Depth

Figure 6. Penetration survey

Penetration was examined, in a manner similar to using a settlement

plate carried out on land, by checking the height of a measuring instrument

(weighing about 60kg) at the time of installation and by checking the settlement plate after overlaying. The results are shown in Table 2

66
The acrylic tube shown in Figure 6 was used to confirm the sand thickness

by core sampling. The results are shown in Figure 7, and a histogram of the

sand thickness in each case is shown in Graph 1.

TABLE 2. PENETRATION DEPTH

Cases Depth

1 20 (Unit: cm)

2 23

3 16

4 16

Unit: cm

0(0m Mesh)

45 60 35 23 15 45 34 6 863 48 5 465 775035 -

80 59 7 8 30 454540 50 25 60 7 8840 60 S~3

45 2035 11 60 22 21 7 50 45 55 60 60 74 50 40 4

1 60 75 155 40 75 780 60 80 156 65 20

15 70 60 35 65 65 140 90 60 75 65 75 60 60 78 65 40

6

5 29 30 30 •25 1 S5 190 90' 65 6

3 85 65 3 55 70 5 6 78570

__ . ,_ . 8

8 30 70 90 75 50 66 Y 66 30 60 65 65 70 45 52 58 50

I I - 9

70 125 110 100 100 75 77 50 30 S1 1 62 62 70 33 32 32 20

70 1015 5 9 5 75 85 45 50 )60 85 85 i55 52-8I2

65 55 35 10 80 65 100 180 20 55 160 60 60 60 60 55 35 ___ 12 35 40 41 25 25 20 2 60 110 30 10 50 50 75 53 55 68 35

140 1.40 45 t20 155 125 70 50 20 0 145 55 25 L70 2640 13

Figure 7. Sand thickness measurement

67
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Survey of Stirring Up of Sludge

The survey of stirring up of sludge was intended to examine how much

sludge vould be stirred up as the overlay sand discharged from the conveyor

barge hit the bottom sediment and what effect the silt contained in the

overlay material would have. Water from the sediment at 1.5m and 1O.Qm was

collected (Figure 8) and SS and turbidity were analyzed. Figures 9-11 show

the changes in SS and turbidity.

At the same time, spot observation was carried on by means of a portable

turbidity meter as well as successive observation, day and night, by means

of a fixed type turbidity meter (the conveyor barge had a water examination

port in the bottom).

A

0 B

IA: String

B: Messenger Support

C C: Transparent Cylinder

D: Sample Takeout Cock

E: Messenger

i

Figure 8. Kitahara type insulation

water sampler

The survey results showed that the background before sand spreading was

less than 5 ppm both near the bottom sediment and immediately below the water

surface and after spreading was a maximum of 40 ppm and a minimum of 2 - 3 ppm

or an average of 5 ppm or less. Thus, there was a limited amount of sludge

stirring.

69

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00*

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72
Survey of Settlement

The survey of settlement was intended to examine how the stirred sludge

and silt in the overlay material would settle with the passing of time. But,

the survey was a failure because a dish was used for collecting samples, as

shown in Figure 12. As the diver appro3ched to check the height of deposition and then departed, the sediment was stirred up. Thus, the measurement

of the height of deposition on the dish involved an unstable factor. Therefore, it was necessary to devise another method of collector installation.

Marker Buoy

) Collector _ish (Glass)

Overlay :--. . . .

Material ".. :: .".--..

Bottom

Sedime;it

Figure 12. Settlement survey

Survey of Laps

Initially, it was expected that whenever sand was spread, the sand would

form peaks as shown in Figure 13 and that such peaks would overlap with one

another whenever the barge was moved back. Actually, however, the sand laid

flat without peaks. (The conveyor barge was operated at 1/20 to 1/10 of its

capacity.) Accordingly, it was not possible to measure the laps. This

survey was, therefore, not successful, but it was satisfying that the overlay

came out flat.

Survey of Unevenness

Unevenness was checked by both echo sounding and lead sounding. As the

bottom sediment before overlaying was flat at an average of -21.1-n, the

overlay was flat as stated earlier.

Survey of Current

A diagram of the current meter used in this survey is given in Figure 14.

73

I

St,
~Expected Form*

Figure 13. Lap surveys

Flashing Light

3m(Beneath 11-

Water Surface OA

Curren~t Observa- Unit24

tion Equipment

Block Diagram

ICurrent Meter, EC-3l11, Special Type, Product of Kaijo Oenki 4 It 2m after SSteel Frame Setting Bottom

Figure 14. Measurement by ultrasonic pulse current meter

74
Typical results of measurement by an N

instrument installed as shown in Figure 14

are given below in current direction and NW NE

speed diagrams against the time zones of the

stirrine' up survey.

The time zone of survey conducted on W E

November 1 was from 14:10 to 16:15 hours,

and the flow directions and speeds from

13:00 to 17:00 hours are shown diagrammatically below. SW SE

S

Water Sampling

14!0 Time Zone 1 6 !s - - TIME

SSW

1 3a 1408 Or 1500 1600 10

ENE -

NE

November 5 Survey Time Zone (9:00-12:00) Flow Direction and Speed

Diagram (10:00- 14:00)

900 Water Sampling Time Zone 12 ?.I

-' i ESE 3 -- -TIME

1000. 1100 NE 1200 E 1300 1400

NE

NrdE

NNE

75

N.
Taking of Video Pictures

Video pictures were taken mainly of the conditions of the overlay along

the center line in the longitudinal direction (120m) of each case and also of

the settlement plate (measuring instrument), stir up, settlement (condition of the dish ), and laps.

Case 1: Pictures taken 3 days after the overlay; sand particles shown clearly

and no unevenness found.

Case 2: Pictures taken immediately after overlaying; finished surface,

measuring instrument, dish, and fish swimming around were

shown in good images.

Case 3: Pictures taken immediately after overlaying; best and stable images

obtained, showing particles of the overlaying material and shellfish

and the conditions of the finished surface, dish, and unevenness.

Case 4: Pictures taken 2 days after overlaying; similar to Case 3, showing

the condition of stirring up and the settlement plate; relatively

good when compared with the pictures of Cases I and 2.

WORKING CRAFTS USED

Working vessels used in the work are shown below.

Vessels Type Number Remarks

Conveyor barge 2,000m3 loading 1 Ship's name C82002

Anchor boat 240ps, 20 tons 1 No.6 Sanko-Maru

lifting capa.

Traffic boat 5Ops 1 For conveyor barge

Inestigation boat 3Ops 5 For various investigations

Working boat 3Ops 4

Survey boat 30ps 1

Tugboat 2,000ps 1

Patrol boat 5Ops 2

76
INTERDEPENDENCE OF TURBIDITY SPREADING AND CURRENT

What effect dic the current have on changes in the turbidity in overlaying? According to the analyzed data, Case 3 had an SSW current flow average of

about 2cm/sec during the spread time period, with the current reversing to

ENE to NE at the end of the spread. In Case 4, the current was NNE at an

average of about 7cm/sec in the spread time period and NNE to NE at an, average

of about 5cm/sec for some time after termination of the spread. Under these

conditions, the turbidity in Case 3 was less than 5 ppm and decreased with

time on the portside of the conveyor barge, but at the front central part,

under the influence of the SSW current, it -nowed a trend of increase by only

2-3 ppm. But, in either case, the tur-dity was low, below 5 ppm. In Case 4,

the conveyor barge was positioned downstream, and at the measuring points

located upstream, the turbidity shcwed no effect from the spread. Thus,

it was confirmed from the range of measuring points around the barge that

the discharge caused little spreadirl of the turbidity, the current had

li:tle effect on the turbidity, and the turbidity was not spreading much. i (OVERALL EVALUATION OF SPREAD METHOD

An overall evalation of each of the spread methods was made as shown

in Table 3. For evaluation, points were given in the order of 5, 4, 3,

and 2 from the best,, and for a weighted evaluation, 50%, 10%, 10%, 10%, and

20% were given in the order of the numbers 1, 2, 3, 4, and 5 in the left

column of the table.ý The evaluation was made of the following items:

Number 1. Sand layer thickness: An average thickness of 50cm or more was

secured in each case, but the rating was

made according to the extent of variation.

2. Unevenne s: Extent of variation of unevenness as

measured.

3. Stirring up: Extent of variation of SS at 1.5m from the

bottom.

4. Settling: Height of deposition, taking the value of

the survey 3 days after the overlaying.

5. Turbidity: Degree of SS.

Points of gain 'and the order of the spread methods are also shown in

Table 3.

77
TABLE 3. POINTS MARKED AND ORDER

Cases 2 3 4

N Item1

1 Sand layer thickness 2? 1? 2! 1?

2 Unevenness O? O) O! 0!

3 Stirring up O 0?! O 0!

4 Settling 0! O 0?! 0

5 Turbidity O O 1? 0!

Overall evaluation 3? 2! 4? 2ý

Order 2 3 1 3

SUMMAkY

Case 3 was determined to be the best method. In this method of sand

spread, a volume equivalent to 25cm of overlay is placed twice successively (by full swing) from a height 10 - 12m above the bottom (middle stage discharging). The fact that this method was found to be the best is attributable to such factors that the sand thickness was stable due to successive discharges and the impact of the overlaying material on the bottom

sediment was diminished by the middle stage discharging with less stirrin,

up causing turbidity and less resettling. In all the methods, turbidity

was nearly completely eliminated through the use of the tremie tube's telescopic function.

The cunveyor barge method is promising as a mobile and efficient sand

overlaying method. This barge system is capable of overlaying sand in a

short period and is applicable to a wide range of areas.

78
SP 0 0 2 3 9 6

SAND OVERLAYING FOR BOTTOM SEDIMENT IMPROVEMENT

BY SAND SPREADER

Kiichi Kikegawa

Japan Dredging A Reclamation

Engineering Association

Kotohira-Kaikan Building

1-2-8 Toranomon, Minato-ku

Tokyo, Japan 105 I

ABSTRACT

N In order to prevent further pollution of the ocean

environment in the Inland Sea of Japan, the Ministry of

Transport conducted a bottom sediment improvement test

by sand overlaying in Hiroshima Bay. Prior to execution

of this test, a test to overlay the bottom sediment with

sand of a thin layer was conducted by using a barge unloader sand spreader. As a result, the following facts

were discovered:

I. It is possible to evenly spread a sand cover

over bottom sediment to a specified thickness

with relative ease.

b. The disturbance to bottom sediment is minor

because the sand is gently spread.

c. Water pollution caused by the resuspension of

bottom sediment nr overlying sand is minor.

It was confirmed, therefore, that the sand spreader

process is feasible for practical use as a sand overlaying process for bottom sediment improvament.---

INTRODUCTION

The Ministry of Transport decided to implement an ocean environment consolidation pilot project in order to prevent further pollution of the ocean

environment in the Seto Inland SeA. A bottom sediment improvement test of

79
overlaying the bottom sediment with sand in Kiroshima Bay was conducted as

a part of this project. The test works commenced in 1979, and various surveys and investigations are still in progress.

Sand overlaying for bottom sediment improvement is one of the measures

for separating seawater from bottom sediment and reducing the release load of

nutrients from the bottom sediment (one of causes of entrophication in the

enclosed sea).

A part of the results of investigations in this test work was presented

at 6th US/Japan Experts Meeting on Management of Bottom Sediments containing

Toxic Substances and effectiveness of sand overlaying has been corroborated.

The problem with execution of the sand overlaying process is how to

spread quality overlaying material over the bottom sediment to an equal

thickness without exception in the required area.

A barge unloader sand spreader of suction dredge type was used on a trial

basis for spreading cover material. Good results were obtained; therefore,

its outline is introduced below.

SAND OVERLAYING PROCESS

The problems involved with the release of organic substances and nutrients from the bottom sediment by sand overlaying are as follows:

a. The overlaying material should be equally spread to prevent positive

exposure of the bottom sediment. Furthermore, after overlaying, the

surface layer should not be disturbed by working anchors and so forth.

b. Quality overlaying material must be used to prevent pollution of the

working area.

c. The surface layer of the bottom sediment is extremely soft, making it

possible for sliding disruption of the surface layer of the bottom

sediment to occur due to the spreading of overlaying material; enclosure of the bottom sediment is thereby disabled. Therefore, overlaying material should be spread as thinly as possible and methods

that partially pile up overlaying material should be avoided.

d. The release of nutrients cannot be prevented if the overlaying thickness is insufficent; on the other hand, it is possible that the release load increases due to consolidation of bottom sediment if the

overlaying thickness is 2xcessive. Consequently, it is necessary to

select a suitable thickness.

e. Reliability is required for the sand overlaying process. It is desirable, therefore, that management is made by means of a work execution management system that is capable of understanding the working

conditions at all times.

80
f. When the sand covering process is actually adopted, a broad area is

involved and facilities that provide a large working capacity (working

area per unit time) are required. Consequently, it is necessary to

examine working methods capable of satisfying these requirements.

SAND COVERING PROCESS WITH A SAND SPREADER

S Various methods can be considered for spreading cover material:

a. Mechanical method (clamshell, belt converyor, etc.).

"b. Hydraulic method.

c. Pneumatic method.

Of the three, the hydraulic method has been popularly adopted for improvement of soft ground. As a broad area sand overlaying process, the hydraulic method makes use of suction dredges. This method is available in

two systems: suction dredge and sand spreader and barge unloader and sand

spreader.

Suction Dredge and Sand Spreader

In this system, a sand pit is provided near the working area; overlaying

material (sand) is stored in the pit; and the sand is sucked with a suction

dredge and fed to tJ'c sand spreader located in the overlaying area by pipeline. The sand ovrlaying work is executed by operating the sand spreader in

back and forth and right and left directions.

Barge Unloader and Sand Spreader

In this system, the sand transported with a barge is sL:ked with a barge

unloader of suction type, fed to the sand spreader by the method described

above, and spread.

A sand spreader of this barge unloader type was used for this test'

work. The features of this process were as follows.

a. The overlaying material (sea sand) is spread after being mixed with

water thereby making it possible to spread over a broad area at a

time. Therefore, sand spreading in a thin layer can be easily

performed.

b. Overlaying on soft bottom sediment can also be accomplished because

partial pile up of overlaying material will not occur.

c. Since the equipment is simple, management ef txecLtioL of work is

easy and working accuracy is high.

d. It is easy to expand the scale of the equipment and cope with largescale work.

81
SAND OVERLAYING TEST

This test was conducted in the Kure area of Hiroshima Bay in July

through October of 1980. Sand overlaying work was carried out in sections

200 m x 200 m and 60 m X 80 m at a depth of 21 m.

In addition to the sand overlaying test using sea sand, investigations

to study the adaptability of oyster shells were also conducted since oyster

shells are produced in large quantities in this region.

The locations of work are shown in Figure 1.

Hiroshima

Hi oshima

Mi4ts t

iss

Figure 1. Location of test point

Overlaying MBaterial Test

Physical, chemical, biological, and organic substance tests were conducted with two samples of sea sand and one sample of oyster shells to determine the various properties of sea bottom overlaying materials. The re- sults are shown in Table #.

Sea sand samples were of coarse particle size containing snells with

silt content of 0.1 - 0.3c,. No organic substances were detected, and,

accordingl7, they were judged to be suitable as overlaying material. The

grain-size distribution is shown in Figure 2.

82
TABLE 1. PROPERTIES OF OVERLAYING MATERIALS

Oyster shell Sea sand I Sea sand 2

_.... Items July 24 '80 July 28 '80 Aug. 5 '80

Hue -- Grayish white Grayish yellow Grayish yellow

Physical Odor -- Oyster odor No No

Test Specific 2.567 z.617 2.622 gravity

Bulk density 0.723 1.13 1.22

Water content % 33.6 4.26 5.74

PH 8.8 9.4 9.4

COD Omg/g 3.7 Not detected* Not detected

T-P mg/kg 460 44 100

P04 -P mg/kg 310 Not detected 40

T-N mg/kg 497 107 35

Chemical NHi -N mg/kg 23.3 4.6 7.5

NO 2-N mg/kg Not detected Not detected Not detected

Test NO -N mg/kg 120 32.8 9.3

TOC % Not detected 0.1 Not detected

fXEAgcl mV 80 90 230

ORP En.HE. mV 290 290 430

Sul- Free Smg/g Not detected Not detected Not detected

fides Banded Smg/g Not.detected Not detected Not detected

All Smg/g Not detected Not detected Not detected

Ignition loss % 0.6 0.9 2.8

C % 11.5 0.6 1.6

H % 0.1 under 0.1 under 0.1 under

N % 0.4 0.3 0.1 under

Biological General /g 5 x 105 600 2000 bacteria /

Test Sulfate reducing

bacteria /g 790 5

Total mercury mg/l Not detected Not detected Not detected

Alkyl mercury mg/l Not detected Not detected Not detected

Cadmium mg/l Not detected Not detected Not detected Srganic Lead mg/l Not detected Not detected Not detected

Substances Total Chromium mg/i Not detected Not detected Not detected

Test Hexavalent mg/i Not detected Not detected Not detected

Chromium

Arsenic mg/l Not detected Not detected Not detected

BHC mg/l Not detected Not detected Not detected

"PCB mg/l Not detected Not detected Not detected

"Not detected" means less than the limit of determination.

83

k-
.C

.00

Cl cay I, sil•t I sand 'I, grave I

0. 0.0

Figure 2. Grain-sizc distribution of sea sands

Investigation of process

To conduct the test, enclosures for the overlaying area were constructed

first using oyster shells.

Next, overlaying using sea sand was executed with z sand spreader. To

ensure that spreading was maintaining the specified thickness, small-scale

pretest areas I and II were established, and pretests were conducted prior

to full-scale operation.

Spreadino.of Oyster Shells

A grab hopper dredge was used for spreading the oyster shells; the

oyster shells loaded in a hopper were grasped with a grab bucket and released

at the fixed position. The water depth at release was varied as a test and

the spreaded form was investigated; based on the result of this test, the

optimum release depth was determined as 15 to 20 a.

The conditions after the oyster shells were spread were surveyed by

divers and also by echo sounding. The results of the investigation are

shown in Figure 3 and Table 2. It was confirmed that oyster shells were

spread to the planned thickness.

Wi~h respect to enclosures, the thickness was 40 to 70 cm in the

peripheral dike with a width of 6.0 to 8.0 m, and the layer thickness at the

center was almost equal at 50 to 60 cm.

84
?N

SFigure 3. Oyster shell overlays

TABLE 2: OVERLAY ENCLOSURE OF OYSTER SHELL'

ocation Thickness Width 1 Location Thickness Widta NO. (m) (a). _ No. (M) .(M)

1 0.55 6.o 11 0.70 6.0

2 0.60 7.0 12 0.40 7.0

3 0.45 7.0 13 0.60 6.5

4 0.55 8.0 14 0.55 6.0

5 0.65 7.0 15 0.45 7.0

6 0.60 7.0 16 0.55 7.5

7 0.70 7.0 (a) 0.55

80.55 7.5 (b) 0.55

90.55 7.0 (c) 0.55

10 0.-70 7.5 (d) 0.60

of Sea Sand S~Spreading 

a. Spreading -_ethod

Spreading of sea sand was carried out with a suction type barge

unloader. A grab hopper dredge conveyed sea sand to a barge as shown in

Figure 4, and the sea sand was dropped into the barge hold with a grab. The barge hold was filled with water utilthe volume of sea sand in the hold

reached the specified level (200 a this time). The mixture of water and sea sand was then sucked with s sand pump and spread over the sea bottom through

a spreading pipe shown in Figure 5.

I 85
Grab hopper dredge

Sand spreader

Spreading pipe

ZI Figure 4. Outline of Sand Spreading Process

Sand sireading 4

p~ pe

Figure 5. Profile of a Sand Spreader

86
Determination of the quantity of spread sand was made through measurement of suction negative pressure of the sand pump. The distance of movement

of the unloader was measured with an advance meter mounted to the maneuvering

winch wire; deviation in the back and forth dire.ction as well as the right

and left direction was managed by i system that made corrections based on

sextant surveying.

b. Management of spreading rate

The qand pumping rate of the unloader can be roughly estimated through

measurement of the suction negative pressure of the sand pump.

:V The flow rate, suction negative pressure, and actual suction height were

measured in the test work section while the pump was running with water. The

flow rate, discharge sand quantity, and suction negative pressure when sand

content varied during sand-water mixture running were calculated, and Table 3

was compiled. The discharge sand quantity during the spreading operation was

managed from the index of suction negative pressure by using Table 3.

TABLE 3. VARIATION IN SUCTION NEGATIVE PRESSURE AND DISCHARGE SAND QUANTITY

BY SAND CONCENTRATION

True Sand Suction negative Discharge sand

. •Concentration oncntrt~o _ pressure, resure mmH_- ~Flow rate quantity

[___ ...... min Standard* max (m3/sec) . (. /h)

2 154 228 301 0.30 51

4 169 243 316 0.29 99

6 169 243 316 0.27 140

8 176 250 324 0.26 179

10 176.8 257 338 0.25 214

12 191 272 353 0.24 248

14 199 279 360 0.23 279

20 206 294 382 0.21 360

The standard value of suction negative pressure calculated for the suction

actual height during sand-water mixture running is the same as the suction

actual height (distance to pump center line from water level in barge)

during the water delivery running test, and the minimum and maximum values

are applicable to cases where the suction actual height varies by ±90 cm

from the standard level.

c. Spreading method classified by test area

rhe spreading method classified by test area is shown in Table 4.

_ _ ,_• _ _ ._ _ _ _._ _"_ _S-
#: ~/

S,/ / I

TABLE .. SPFEADINi METHOD CLASSIFIED BY TEST AREA

Precest area I

2nd-3rd 4th-6th Pretest

Item 1st row row row area II Test arcs

Spread Per advancement 4 min. 3 min. 3 min. 3 min. 3 min.

time Per row 136 min. 102 min. 69 min. 69 min. 69 min.

Advance distance at a

time 2 m 2m 3 m m 3 m

Spreading pipe location -10 m -10 M -10 M -5 m -I0 M

Parallel moving distance 6 m 6 m 6 m 6 m 6.5 m

In pretest area I and II', investigations of overlaying conditions and

of influence over the bottom sediment and water quality were carried out to

///"iishown determine in Table the execution 5. method to use in the actual work. The results are

TABLE 5. COMPARISON OF PRETEST AREA INVESTIGATION RESULT

Pretest Pretest Difference

Item Description area I area II (II-I)

Resus- Turbidity 1.5 above 2.14 2.31 0.17

pension SS (mg/l) .bottom,(deg) 9.43 7,29 -2.14

Upper Turbidity 1.35 2.39 1.04

layer (deg)

SS (mg/l) 2.63 3.30 0.67

Influ- Ine-" Turbidity mediate 0.39 1.05 0.66

ence layer (deg) SS (mg/1) 2.63 2.97 0.34

Lower Turbidity 0.35 1.48 1.13

layer (deg)

_ SS (m /1) 3.43 3.70 0.27

Irregu- Mean value TCm) 4.59 5.67 1.08

larity Standard deviation (cm) 1.70 1.81 0.11

Tick- Mean value (cm) 37.43* 55.52

ness Deviation (cm) 6.58 [ 10.44 3.86

The values of the 4th-6th rows obtained by 3-min.spreading, 3-m advancement, and 6-m parallel movement, which are the same as that of pretest

area II, were adopted as the values in pretest area I for the irregularity

investigation and overlaying thickness investigation.

88

*1' -

* . 4
N - .•. -

Better results were obtained in pretest area I when compared to area Ii

regarding turbidity, suspended solids, irregtl'arity, and ",verlaying thickness.

Because the spreading pipe located 5 n below the water surfice caused the

center of overlaid sand to deviate from the center of the s;,reading pipe by

2 m, it was decided to carry out spruading with the spreading pipe located in

a position 10 m below the water surface. From the results obtained, it w~s

judged possible to overlay sand to the specified thickness; therefor', spreading work in the full-scale test area was executed such that spreading was for

3 min, advancement was 3 m, and tht barge pari belly moved by 6.5 m after

completion of spreading in a row, as shown in !able 4. The work w;:s managed

by further dividing the test area into subsections as shown in Figure 6.

6 .3 area area

Investigation of overlMing sat-i thickness and sinking

After completion of the overlaying in test areas, the conditions of the

overlying sand in the vertical direction were investigated by using overlying

sand thickness gauges, core samplers, sand samplers, and dcpth measuring bars

(Table 6).

89
V

I

TABLE 6. OVERLYING SAND THICKNESS INVESTIGATION

I Pretest area Pretest area

Item I . II rest area Remark

Sand thickness 3 units 3 units 10 units 3 after oyster

gauge shell spread.

16 after sand

spt-ead

Core sampling 8 units 4 units A4 units 16 measuring bars

(2 of them (2 of tz:a, (1 %f thee used together in

for particle for parti-ie for parti- the test area

size size cle size

analysis) analysis) analysis)

Sand sampling 7 units 7 units 24 units 24 measuring bars

used together in

the test area

pth measuring 30 places 30 places 455 places

ar

Overlying Sand Depth Gauge

a. Method of investigation

Overlying soil depth/settlement gauges were erected in the positions

shown in Figure 7; the height of the top of each overlayer thickness gauge

(Figure 8) was measured before and after spreading. In this way, the overlying sand depth and settlement were measured.

b. Results of investigation

The results of the investigation are shown in Table 7.

Accurate details are known because only a few days passed after s-reading, but it can be estimated that the settlement oi sea sand is larger than

that of oyster shell.

Depth Measuring Bar

a. Method of investigation

By thrusting depth measuring bar. of i5 mm (diameter) x I m (length) into

overlying sand, divers investigated overlying sand depth by response.

Depth measuring bar investigations were carried out at the same time as

the core saripling and sand sampling measurements were made.

90
--1 settlement

- A.4 i * scale *~4 - -- -d - .r sand

- ii: "\ 22 mnn steel bar

driven to bearing stratum.

Figure 7. Location of overlayer Figure 8. Overlayer thickness/ thickness gauges settlement gauge

TABLE 7. RESULTS OF MEASUREMENT BY OVERLAYER ThICKNLSS GAUGE

Date of Layer

measurement thickness Settlement

Gauge No. (cm) (cA) (cI) Remarks

I July 24 25 25

2 July 26 50 25 After oyster shell spreading

3 July 25 20 20

1 40 35 450 incline

2 August 20 80 22 200 incline

3 60 5

4 25 12

5 50 13

6 August 1 75 18

7 30 10 300 incline

8 60 21

9 46 26

10 35 -- Measure bar slipped off

11 45 27 300 incline

12 2055 40 450 incline

13 August 20-. Fell down

14 35 18

15 45 25

16 .... Fell down

91
b. Results of investigation

The results of investigation are as shown in Table 8 and Figure 9;

variation coefficients ranged from 0.14 to 0.38.

TABLE 8. OVERLAYER THICKNESS MEASUREMENT RESULTS BY DEPTH MEASURING BAR

Ite Standard

:Are~a Mean value deviation Variation

(cm) (cm) coeff.

Pretest area I (a) 66.60 15.34 0.23

Pretest area I (b) 35.80 5.72 0.16

Pretest area II 57.91 7.84 0.14

Test area 1 50.98 19.43 0.38

Test area 2 41.34 6.41 0.16

Test area 3 52.15 17.41 0.33

Test area 4 37.68 8.43 0.22

Test area 5 38.38 10.78 0.28

Test area 6. 37.04 10.31 0.28

Test area 7 39.87 6.25 0.16

Test area 8 42.04 6.16 0.15

est area 9 41.10 10.22 0.25

Core Sampling and Sand Sampling

a. Method of investigation

(1) Core sampling

After overlaying work, tubes made of acrylic resin were dri,:en into the

overlying sand by divers, columnar samples were collected, and overlying

sand depth and sand penetration depth into the original sea bottom were

investigated (Figure 10).

(2) Sand sampling

After overlaying work, samplers (Figure 11) were pushed into the overlying sand by divers, columnar samples were collected, and the overlying

sand depth and sand penetration depth into the original sea bottom were

measured.

b. Results of investigation

Results of the investigation are shown in Tible 9. The correlation between measured values obtained with depth measuring bars and measurements

obtained with samplers is shown in Figure 12.

92

, I I I I I I I I I I I I I I I I I I Il
- 1 " 40 a a ra ag joa 4N:o so A 0 1 eea mes~a* - Al

.

1 

sp a -

_NNU aIE I- Is aI OF £

a N doe am , , a a a , a ,. a a a , . , , , .

a mia m w;

41N . a- a - f a

4 - •.--

40 ItI oI ma' :. id of . 4 m

A 

a a 

ma,

Sa aanAnao 

a v 

a d . a 'I.e we

Figure 9. Measurement records of overlayer thickness with depth m easuring bars. unit: cm

93
handle

core tute C lt --

Si sand /~san__dd san

sinked /"-i d

"silt

sit

€/

Figure 10. Core tube Figure 11. Sand sampler

Correlation of Bar (5, 7, 8, 9) to Correlation of Bar (Li, 2, 3, 4) to

core (5, 7, 8, 9) sand (Li, 2, 3, 4)

goa a

60 70-

(j 36-- 0

30,

32, ' 4e 3 5O ~ 75

Bar (5, 7, 8, 9) tar di, 21, 3, 0,)

Figure 12. Correlation of core sampling and sand sampling measurement to

bar measurement

94
TABLE 9. COMPARISON, OF RESULTS OF CORE SAMPLING AND SAND SAMPLING

_ Core Sa ling Sand Sampling

Sandi Sinked Sand Sand Sinked Sand

thick-f depth thickness + thick- depth thickness

Item ness (crn (cm) &inked (cm) ness (cm) (cm) sinked (cm)

Mean 32.5 4.62 37.1 44.4 5.86 50.3

value

Pretest Standard 7.791 1.22 7.87 6.00 6.01 9.35 area deviation _ "

Variation -

coeffi- 0.240 0.264 0.212 0.135 1.03 0.186

cient _ Mean Mal 

value 29.5 3.75 33.3 40.4 12.3 52.7

Pretest Standard

11e deitinda deviation 8.051 1.30 7.82 8.36 5.12 12.6

Variation I

coeffi- 0.275 0.347 0.235 0.207 0.416 0.239

cient _

Mean7.3 4.55 41.9 38.7 5.92 44.4

value

Standard

est deviatio 7.44] 0.711 7.51 7.33 1.94 7.85 ara deviation

Variation

coeffi- 0.199 0.156 0.179 0.189 0.328 0.177

cient

95
Particle-Size Analysis

Particle-size analysis was made with core samples obtained at the

boundaries in order to investigate penetration of overlaying material into

the bottom sediment.

a. Method of analysis

As the method of analysis, 10-cu samples were produced as shown in

"Figure 13 out of two core tube samples each in pretest area I and Ii and one

core tube sample in test area 5; particle-size analysis was based on

JIS'A 1204.

sand

sand penetration

2

3 • silt

core tube

sect. No.

Figure 13. Sectioning of core tube sample

b. Results of analysis

The results of analysis are shown in Table 10. Penetration of overlying sand into the bottom sediment was relatively small.

Overlay Form

The overlay form is shown by a histogram indicated in Figure 14 from

the results stated above. An almost level surface to a mean depth of 42 cm

resulted. The mean penetration depth was 6 cm.

Investigation of resuspension

Resuspension of the bottom sediment and overlying sand during sand

overlaying work was measured with a portable turbidity meter. In addition,

water samples were collected and laboratory analysis of turbidity was conducted. The results (shown in Figure 15) showed that resuspension of the

bottom sediment is up to 1.5 m above sea bottom.

96
TABLE 10. PARTICLE-SIZE DESTRIBUTION OF CORE TUBE SAMPLES

Location Core tube Clay and silt content Sand and gravel pebble

Area No. sec. No. (74 p or less) % content (over 74 p)%

retest 1 0.5 99.5 rete1t 12 0.1 99.9

3 52.8 47.2

4 94.1 5.9

1 0.2 99.8

2 0.2 99.8

3 39.9 60.1

4 91.9 8.1

1 0.2 99.8

Pretest 2 1.6 98.4

area 3 93.4 6.6

II 4 93.5 6.5

1 0.2 99.8

2 0.4 99.6

3 83.1 16.9

4 95.1 5.0

1 0.1 99.9

Test 2 0.1 99.9

area 4 3 77.5 22.5

5 4 96.6 3.4

Investigation of Resettlement

Two types of glass laboratory dishes, 30 cm diameter x 8.5 cm high and

30 cm diameter x 15 cm high, were placed on the overlying sand by divers

immediately after sand overlaying work, and resettlement was investigated by

divers for three days after sand overlaying work.

The results of the investigation are shown in Table 11. Accumulation of

sand is observed in all dishes, and this sand is considered to be spread sea

sand of slow settlement or resuspended spread sea sand after arrival at the

bottom.

Investigation of Finished Surface

To determine the irregularity of the finished surface of the sand overlay, a pole was placed on top of two adjacent peaks of sand as shown in

Figure 16 and the depth of the valley between the peaks was measured. The

depths of these valleys were 6 to 7 cm ot maximum, and conspicuous irregularity was not observed.

97
r7 nasurement by depth measuring

measurement by core sampler

measurement by sand sampling

i1 '

'0-

Distribution

/ 6 2/ZI J/ IV 4 46 .5/ .56 61 66 Sand layer thickness

Figure 14. Overlayer thickness histogram

Investigation of Turbidity

In order to investigate the range and diffusion of turbidity generated. during sand overlaying work, water samples were collected at three layers at

15-min intervals beginning 30 min before commencement of sand overlaying. Sampling positions are shown in Figure 17. The turbidity of these samples

was 6ieasured.

The results are shown in Figure 18; very little turbidity caused by

sand overlaying work was obsery."d.

98
Portable Turbidity meter

Beginning of material 1.5 m above sea bottom

6 release

4

2-

45 30 0 15 30 45 60 Hour (min.)

8:10 8:15 8:4-5 q:oo' :73 9:30 9:45 Time (hour: min.)

Laboratory

8 'Analysis

.4 -

/o AS Height above

sea bottom

1. 15 min. before release

2. immediately after release

3. 30 min. after release

4. 60 min. after release

Figure 15. Typical results of the resuspension investigation

Confirmation Investigation

In order to collectively understand the sand overlaying conditions, the

conditions of the bottom were investigated by using a sonar before and after

sand overlaying work.

The results of the investigation are shown in Figure 19. The conditions

of the bottom are almost identical.

99
TABLE 11. RESULTS OF RESETTLEMENT INVESTIGATION

o . Fdy later 2 days later 3 days later Remarks

1 1 mm 1 - 1 - several tiny shrimp,* Sand, -ilt Sand, silt Sand, silt 1 tiny crab (dead)

(1/3) (1/3) (1/3)

2 1 -M 1 -m I -m several tiny shrimp,

Sand Sand Sand tiny crab (dead)

3 1 mm 1 -, I i" 1 tiny crab

Sand Sand almost silt

4 1..a In 2 m

Sand Sand Sand, silt

5 l1m 1,, 3mm

Sand Sand Sand, silt

(minor)

6 1am** 1.5 mm 3 mm 3 tiny shrimp

Sand, silt Sand, silt Sand, silt 4 tiny crab

(minor) (minor) (minor)

7 1 mm 1.5 ma 1.5 mm 15 tiny shrimp Sand,. silt Sand, silt Sand, silt 9 tiny crab,

(minor) (minor) (minor)

* Check of creatures was made when dishes were brought up 3 days later.

** Silt (minor) means minor unmeasurable volume,

IScale

S.... : _= . . : •.-. S....... " . .. . ., •_Po le

Figure 16. Surface irregularity measuring uethod

100
No.ISpreading (69 m.) 3 m below the water surface

---- 1/2 -----of water depth -3 m above sea bottom

6.

S, J)5 35 4s 60 7o 9o /o5 hour (min.) No.1

C IS 4!:!0 8:4 9:x ?A5 9:30 ?:45 ,0:o /0:16 /,0J0 time(hour:min.)

:1o.2 Spreading (69 min.) "Barge unloader a- Gr~beo~per-

.0--

S2L

30 i- 0 15 30 45 60 70o 0 l05 hour(min.) 8:15 8:30 8:45 9:00 ?:/5 f30 9:45 /$-0x 10:/S /0:30tire(hour:min.) Figure 17. Turbidity

investigation

pcints No. 3 NSpreading (69 mi .)

4-

0 10 1,5 30 4,5 60 70 90 /05 hour(min.) 6:/3 8:30 8:4,5 9:00 9:?/S f:30 :45 /0:00 /0:/1 10:30 time(hour:min.

Figure 18. Results of measurement of turbidity influence investigation

101
Lower line: Before sand overlaying

Upper line: After sand overlaying

overilay area plan Scale V/H 101o

-IL

I I - -

KK __ .;-

Figure 19. Sectional view of overlying sand form

102
CONCLUSIONS

The following conclusions can be drawn from this study:

a. The results of these investigations showed that the sea sand overlaying process using a barge unloader sand spreader is fully capable

of finishing the entire area of spreading to the specified thickness

with little irregularity.

b. In the range investigated, conspicuous differences were not observed

in the influence of depth of spreading.

c. The sand overlaying work did cause turbulence in the bottom sediment;

but contamination of surrounding water did not occur.

d. This was the first attempt at a sand overlaying process for bottom

sediment improvement by spreader, and success levels were higher than

expected.

e. A new type of sand spreader will have to be ,eveloped for future

large-scale sand overlaying work; it will not be possible to simply

increase the size and scale. The new type r: sand spreader will have

to incorporate large-size spreading pipes, equipment for feeding

spreading sand at a fixed rate, and ship-operating equipment that does

not require Anchors.

f. A follow-up investigation is ini progress to prevent the release of nutrients from the bottom sediment after sand overlaying; the findings

will be reported at a later date.

103
I

AD P002 3 9 7

STUDIES ON CAPPING OF CONTAMINATED DREDGED MATERIAL

IN NEW ENGLAND DIVISION

R. C. Semonian

DAMOS Program Manager

New England Division

Corps of Engineers

424 Trapelo Road

Waltham, MA 02154

ABSTRACT

"Contaminated dredged sediments were covered with

less contaminated sediments in a controlled and mon&-

tored series of operations in Long island Sound at a

depth of 20 a. Observations have yielded useful information on formation of mounds, stability under

stress of wave and current energy, and technology of

marking, measurestent, and data acquisition. Efficiency of the caps of two dissimilar sediments is

evaluated in terms of physical behavior and chemical

leaching.,

The obligation to manage the disposal of dredged material in a manner

which is responsive to regulatory mandates and to public concerns led our

agency to initiate the development of subaqueous construction methods

popularly called "capping." This will sumarize the planning, operational

features, and observations to date of one such operation conducted since

1979 off New Haven, Connecticut.

As historical background, the New England Division of the Corps of Engineers began various studies of dumping grounds in 1967 through a series of

contractual agreements with marine sciences institutions in our region.

These studies were the forerunners of a more formal program for monitoring

environmental effects which is known by the acronym DAMOS. This program, employing a prime contractor, continues the association with academia through

various subprograms. A most significant aspect of these early efforts was

the developmert of techniques and subsequent evolution of much of the instrumentation without which the undertaking being described would not have been

practicable.

The problem to be addressed by "capping" arose as a result of the need

to restore certain channels in Connecticut Harbors to safe depths particularly

at Stamfori Harbor, located in Long Island Sound. Sediments which had accumulated over 20 years were enriched with various heavy metals and hydrocarbons

to a degree which created concern over conventional subaqueous disposal.

Historically, Long Island Sound, a semienclosed estuary, had been used for

disposal, but was in the spotlight because of the clean water initiatives.

104
All activities were suspect. Therefore, even though no firm scientific basis

had been advanced as cause for concern, it would not have been possible to

dump sediments within this water body if the public perception was that they

were contaminated.

In the absence of alternative means of disposal, and in light of mounting economic pressure to maintain the channel, our agency advanced a plan

designed to isolate the contaminated sediments beneath a strata of materials

accepted as being "clean." While past observations of disposal area mounds

had yielded much practical information with regard to dumping operations,

there were no instances where mounds were formed entirely of what would be

characterized as "maintenance," or sediments of recent origin. Therefore,

we were interested in sediment behavior with regard to mounding, lateral

spread, erodability, consolidation, and any other physical factors which

might be observable. A plan was formulated whereby two mounds of contaminated

material would be formed at marker buoys place' within the I-mile-square disposal area. Marker buoys were to be spaced approximately 1000 m equidistant

foom a relic mound formed in 1974. The mounds were oriented normal to the

tidal flow in order to minimize any effects of one on another. A feature of

the plan was to utilize and compare the effectiveness of cover material of

two distinct sediment types: fine-grained cohesive silts and clays in one

case, and fine sands in the other. The plan and its results are generally

discussed in this paper. Appendix A contains a more detailed discussion of

the capping study.

The plan called for periodic observations of the development of the

mound and its cover by bathymetric surveys supported by visual and photographic evidence. To this end, wires were placed along the bottom radiating

from the center with appropriate markings, and stakes were imbedded as a

further aid to measuring lateral spread and depth of the mounds. In retrospect, these provisions were unnecessary since, ultimately, the boundaries of

each mound were readily identifiable by sharp contrast in color and texture,

and the natural delineation provided by an extensive population of the stalk

hydroid corymorpha found over the entire area. Extensive baseline measurements of both physical and chemical parameters were logged prior to the start

of dumping operations.

As the average water depth of the disposal area was 20 m, it was possible to utilize taut-wire moored buoys as markers which provided a constant

reference to the tow boat operator. Even under adverse conditions, disposal

generally took place within 25 m of the designated point. The records indicate that, if anything, the mounds formed more steeply than initially predicted, and that future dumping operations should address this aspect.

Two mounds of the Stamford contaminated material were constructed:

south, 37,800 cu a; and north, 26,000 cu a. Evaluation during this phase

indicated excellent correlation of mound volumes with scow measure. It was

estimated that greater than 80 percent of the material being dredged by clamshell bucket was transferred from the dump scow to the bottom as a cohesive

unit, forming a mount. The balance formed a turbidite-type deposit radially

from the disposal point. Obviously, the type of dredge utilized has a most

105
significant effect on the final angle of repose. This was most apparent when

capping material was dredged from the New Haven Harbor channel. The south

pile was capped by 76,000 cu m of bucket-dredged cohesive sediment, and the

north pile was capped by 84,000 cu m of sandy maLerials dredged by the Corps

of Engineers hopper dredge ESSAYONS. While each cap attained the thickness

and extent of coverage desired, the contrast in surface texture was pronounced

and, as it turned out, significant.

Upon completion, the sand cover on the north had a maximum thickness of

3.5 m. This cape was a smooth blanket and difficult to penetrate, judged by

diver's reports. The south mound had a cap of up to 4 m thickness, characterized by roughness features attributable to the large clumps of cohesive

sediment.

Following the dumping operations, periodic observations and measurements

began. The first, approximately I month after completion, detected slight

consolidation in each mound, which was consistent with expectations. However,

4 months later, another survey indicated that approximately 10,000 cu m had

been displaced from the top of the south pile. While the integrity of the

cap remained whole, the phenomenon gave rise to extensive analysis of the

probable cause.

Through deduction, subsequent observation, and based upon theoretical

calculations, the logical explanation for the loss of material was the wave

energy developed by passage of a hurricane in the third month after deposition. The conclusion reached was that the high roughness factor of this

mound resulting from clumps of cohesive sediment interacted with storm waves

to create a shear stress and cause movement. The two other mounds, though

in slightly shallower water, possessed smoother surfaces and were

unaffected.

Observations have continued on a regular basis since the storm event,

with no further changes being detected. Chemical and biological observations

continue as well in order to measure what, if any, special characteristics

can be attributed to the presence of the mounds. Based on observations on

other mounds, we expect that the roughness factor of the south mound will be

overcome in time, primarily by biological activity, and as a result of

fracturing and normal erosion.

From our studies we have thus far concluded that certain essentials

should govern the choices available to the manager. If possible, cohesion

of the underlying material should be maintained by choice of dredging equipment. The exposed surface area of the resulting mound should be as small as

possible, but may need to be extended when working in shallow water to reduce

exposure. Covering materials, if cohesive, should be reworked by dredging,

or smoothed after dumping if roughness poses a prolslem in the energy field

present.

The degree of coverage necessary to inhibit any diftu3ion to the water

column has not been determined, and there is question whether field measurements will be sensitive enough to verify any theoretical model. .erefore,

lob
the approach should be a conservative one, based on whatever stability calculations are possible. A key element in any similar operation is the availability of accurate control and sounding equipment with the capability to

replicate exactly each line of measurement and sake continuous comparisons.

This equipment is the manager's eyes, and is indispensable.

107__ _ _ . __j
SCIENCE APPLICATIONS, INC.

AD P002398

"CAPPING' PROCEDURES

AS AN ALTERNATIVE TECHNIQUE TO

ISOLATE CONTAMINATED DREDGE MATERIAL

IN THE MARINE ENVIRONMENT

DAMOS CONTRIBUTION #11

Written Statement submitted to:

U.S. House of Representatives

Committee on Merchant Marine and

Fisheries

May 21, 1980

Submitted by:

Robert W. Mortcn, Ph.D.

Science Applications, Inc.

Ocean Science & Technology Division

Newport, RI 02840

108

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INTRODUCTION

- -- ) Many of the major harbors on the northeast coast of the

United States require extensive dredging of material that is contaminated with industrial waste products, principally heavy metals

and PCBs. Because of the large quantities to be drLdged, the lack

of suitable upland or shore line disposal sites, and the prohibitive

costs of transport beyond the continental shelf, placement of these

sediments on the shelf is often the only viable method of disposal.

During the past several years, attempts have been made to isolate

small amounts of this material by covering it with cleaner material

through specific management techniques such as dredging from the

head to the mouth of an estuary, dredging docks and other "hot*

spots during the initial phases of the operation, and combining

clean material from nearby dredging operations at a common disposal

point. The success of these procedures has led to the development of

-- capping' operations in which larger volumes of contaminated materials

are dumped at a specific point and then covered with cleaner material

as part of a carefully managed and monitored program of dredge spoil

disposal..••

One such capping operation has been conducted by the

New England Division of the U.S. Army CcrpS of rngineers, and

several other capping procedures have been nroposed for ongoing

and future disposal operations. The purpo3e of this testimony is

to describe the results of the New England cperation and to discuss

the feasibility, costs and possible ecological effects to be expected

in future capping operations.

STAMFORD-NEW HAVEN CAPPING OPERATION

The extreme shoaling conditions existing in Stamford and

New Haven harbors required that dredging of these areas be conducted

during, 1979 to insure passage of commercial anJ ýarticularly oil

related traffic to termainals in those cities. Because bulk sediment

analyses indicated that sediment originating from Stamford Harbor

would be rich in heavy metals, management procedires were initiated

to "cap" the Stamford material with silt and sand from New Haven

Harbor. The objectives of these capping procedures were to isolate

109
the enriched material from the benthic fauna and the overlying

water column and to evaluate the relative merits of sa.d and silt

as capping materials in terms of coverage, stability, effectiveness

in isolating contaminants and recolonization potential.

Monitoring of the disposal operation was conducted as part,

of the Disposal Area Monitoring System (DAMOS) and consisted of

precision bathymetric mapping of spoil distribution, visual observations of the spoil surface and margins, chemical comparisons of

spoil and natural sediment and sampling of benthic populations for

recolonization and binaccumulation studies.

Baseline stucies of all those parameters were made prior to

disposal. Replicate precisicn bathymetric surveys, diver observations

and chemical sampling were used during the disposal operation to

monitor the volume and distribution of Stamford spoil at the

disposal site, to manage the capping operation insuring coverage of

the enriched spoils and to measure the thickness and distribution

of capping material. Following disposal, additional replicate

surveys were made and are continuing to monitor the stability of

the spoil mounds created and to assess the long term effectiveness

of the capping procedure.

The precision bathymetric survey monitoring procedures

combined with the diver observation have resulted in data which

represent a significant improvement over previous disposal monitoring

efforts for several reasons including: 1) use of precision navigation

control to survey at 25 meter lane spacing, 2) the nearly flat

bottom available to provide a baseline datum, 3) the application of

computer software to complete data sets to provide better calibration

between surveys, 4) the careful management of the disposal operation

to create topographic features for precision meesurements of volume

and 5) the ability to combine visual observations with physical

measurement& to more completely evaluate the environmental factors

affecting the dredge material.

Whether or not these conditions can be duplicated in other

areas will be seen in the future, however, this study provides a

unique opportunity to accurately measure spoil volumes and evaluate

the importance of such environmental parameters.

110
As described earlier there were two major objectives to be

achieved through disposal of spoils at the Central Long Island Site.

(Figure 1) These were: 1) containment and isolation cf Stamford

spoils by capping with New Haven material; and 2) an e.aluation of

the effectiveness of the procedure in general, with particular emphasis

on the effectiveness of sand versus silt as a capping material. In

order to compare the sand and silt caps, two disposal points were

designated 1000 m north and south of the spoil mound created by the

New Haven project in 1974 (Figure 1). The south site was designated

for capping with silt from the inner harbor and the north site with

sand from the outer breakwater area of New Haven Harbor. The

North-South orientation was selected since tidal flow through the

site is in an east-west direction, thus potential effects resulting

from the older mound would be minimized.

Precision disposal of Stamford spoils was essential to

minimize their areal distribution prior to capping. This was

accomplished through installation of two, taut-wire moored buoys

at the designated disposal points using a Trisponder system for

navigation control. Towboat operators were then instructed to

dispose of material close aboard the south side of each buoy. Even

under adverse conditions, disposal generally took place within

25 meters of the designated point.

Initial disposal of Stamford material took place between

March 25 and April 22, 1979 at the southern disposal point. After

April 23, silt from New Haven was dumped at the south site to

provide capping material, and disposal of Stamford spoils was

restricted to the north site. Disposal of silt continued until June

15 when dredging was halted to prevent impact to oyster larvae by

siltation caused by the dredging operation. Likewise, dredging of

Stamford Harbor and associated disposal at the north site was halted

on June 15. Petween June 15 and June 21, the hopper dredge ESSAYONS

removed sandy sediment from the mouth of the New Haven harbor and

used this material to cap the north site.

Disposal of dredge spoil from Stamford Harbor at the

southern site reached a total of 37,800 m3 (based on scow load

records) on April 22, 1979. A survey of the site was conducted on

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April 24, to determine the distribution of spoil material prior to

capping (Figure 2). This survey indicated that the disposal procedure

was successful in developing a small mound approximately 100m in

diameter and 1.25m thick.

Close examination of the vertical profiles for lanes 13-16

(Figure 3) indicates that the topography of this mound was quite

variable, and thicknesses of two meters relative to the initial

bottom were present. The rough topography exhibited in the vertical

profiles was substantiated by diving observations and attributed to

the cohesive nature of the spoils. Toward the margins of the spoil

mound, specific barge loads could be identified as separate topographic features.

Calculations of total Stamford spoil detected relative

to the baseline survey accounted for approximately 90% of

the estimated volume deposited. The contour difference chart

(Figure 4) indicated that there was additional material present

beyond the immediate spoil mound, and it was possible that significant

amounts of spoil might not be detected by acoustic measurements.

This problem was addressed through a combination of visual

diver observations and precision (50m spacing) remote sampling of

the fringes of the mound with a Smith-McIntyre grab. Daring the

period of disposal an extensive population o! the stalk hydroid,

Corymorpha, was growing over the entire bottom. Howev,2r, when

dredge spoil was present to any significant degree, these hydroids

were covered or destroyed. Consequently, divers could identify

the boundary of the spoils by the presence of absenc- of these

animals. Furthermore, the dark, organic spoils provided a sharp

contrast to the natural, brown oxidized muds of the d~sposal site

thus the thickness of spoils on the margins of the mound could be

directly measured in the grab sampler.

The most striking result of these measurements was the

rapid decrease in spoil thickness at the rargins of the spoil

mound. In the east and west directions the change from thickness

greater than 50 cm to less than 5 cm occurred between 100 and 150

meters from the disposal point; while in the north-south direction,

the change was between 50 and 100 m. In either case, it was apparent

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that the cohesive nature of the spoil material was crstxng a

definite mound with discernable boundaries that could be detected

acoustically to a spatial accuracy certainly better than 50 meters.

From these data, it is apparent that for cohcsive spoils

dredged with a clanshell bucket and transported by scow, most of

the sediment (> 30%) is transferred to the bottom as a cohesive unit

and forms a mound, while the remaining material forms a

turbidite type deposit radially from the disposal point since the

coarseness of the particles in-the fringe areas have been observed

to be inversely proportional to distance from the disposal point.

Furthermore, these data indicated that the initial disposal of

Stanford material was tightly controlled by the taut-wire buoy and

subsequent capping with New Haven material should be successful.

Disposal of additonal Stamford spoil at the north site was also

accomplished successfully dnd a monitoring survey conducted on

21 may (Figure 5) indicated the development of a small mound similar

to that observed at the south site. twenty-six thousand cubic

meters of Stamford material were deposited at this location prior to

capping.

As described earlier, silt from Hew Haven Harbor was

dumped on the Stamford material at the south site and Aand from the

breakwater area was used to cap the northern site. All capping

procedures were completed by June 22, 1979. One Jur,- 20, a survey

was made of the southern site (Figure 6) to determin* the success

of the silt capping operation. The contour chart and the vertical

profiles (Figure 7j both indicated a distinct mound had developed

at the disposal site with a minimum dept:& of 16 meters and a thickness of up to 4 meters over the Stamford spoils. Because the silt

material from New Haven was cohesive, the resulting spoil mound

did not have extensive spreading. Although the vertical profiles

indicate all Stamford material was capped, future operations with

silt should be designed to spread the capping sediment and reduce

the thickness to some extent. The volume of NVW Haven spoil

dumped at the snuth site was estimated .t 76,000 m3 from scow load

measurements, of which 72,000 m3, or 95% was accounted for by

volume calculations.

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Capping of Stanford spoils at the northern disposal site

was accomplishedlin six days using the hopper dredge ESSAYONS to

create a sand layer. Management of this operation was aided by a

bathymetric survey on June 19, to determine any areas that were not

covered by sand, and the dredge was directed to dump adeitional

material east of the disposal buoy to insure complete coverage. A

final s'rvey was co.,ducted on June 22, after completion of the

capping operation (Figure 8). This survey and the associated

vertical profiles (Figure 9) indicate that all Stamford spoils were

capped by the sand material. However, since the sand was less

cohesive, it tended to flow during deposition thus creating a

broader, flatten mound than that developed by silt at the southern

site.

At the time of the June 22 survey the capping layer had

a maximum thickness of 3.5m over the Stamford spoil mound. This cap

Was a smooth blanket of sand that divers were unable to penetrate

more than 10-15 cm by digging with their h.nds. A calculation of

the volume of spoil and sand deposited since the May 21 survey

indicated an increase of 33,000 u 3 . This volume compared favorably

with dredge volumes specified by the ESSAYONS, however, large correction factors based on density and water content of ibe sand,

made comparisons tenuous and calculations of volume an, percentage

lost to the water column meaningless.

The results of these surveys indicated that the capping

procedures employed during the Stamford/New Haven disposal operation

were extremely successful. The precision disposal of Stamford

spoils resultedi in a small compact mound that was readily covered

with New Haven material. Apparently, there is little difference

in the ability 6f sand or silt to accomplish the desired capping.

In the case of sand, the capping layer is not as thick, but the

smooth, dense nature of the deposit acts as a tough, impervious

blanket over the capped sediment. Silt depositi on the other hand,

derive their capping ability from the cohesive nature of the sediment,

daveloping a thicker deposit with rougher micro-topography.

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Several recommendations for future capping operations

can be made based on the data obtained from this study.

"* The spoils to be covered must be cohesive to reduce their

spatial distribution. This would normally be the case

since the forces that attract pollutants to the spoils

also cause cohesion. However, dredging procedures should

be conducted in a manner to preserve this cohesiveness.

"* Point dumping of the material to be covered should be

done as accurately as possible, preferably with a taut wire

moored buoy as a disposal marker.

"* Disposal of the capping material should be accomplished

as soon as possible also using the buoy as a marker.

"* After disposal of approximately 2/3 of the capping material

at the disposal point, the remainder should be dumped in

a circle with a radius equal to that of the initial spoil

mound to insure capping of the flanks.

"* Monitoring of the capping operation with bathymetric

techniques should be done during disposal to allow for

modifications in disposal operations required to insure

coverage.

Prior to the disposal operation, chemical and biological

samples were obtained from the proposed disposal site to provide

baseline data for future monitoring. Bulk analyses of sed-ments

from each harbor and the disposal site were made and used to develop

statistical criteria for identifying sediment fror each location.

Using these criteria, it was then possible to contirm that the

capping material was in fact New Haven spoil and that Stamford

material was not displaced toward the surface of the mound during

the capping operation.

Baseline benthic population parameters and infaunal body

burden measurements were also made prior to disposal, however,

post disposal data have not yet been analyzed.

Although the operational techniques for cipping Stamford

material with silt and sand from New Haven Harbor were successful,

the effectiveness of the procedure depends on the stability of the

resulting cap and its ability to isolate the enriched spoils from

the biota and the water column. Consequently, following deposition

124
of the spoils the thrust of the monitoring effort changed to

evaluation of the stability of the resulting mounds with time. Again,

this was a multidisciplined effort involving physical, chemical and

biological measurements.

On 7 August 1979, a bathymetric survey of the North

disposal site was conducted that indicated there were no major

changes in the topography of the spoil mound. Although the specific

"tooographic features between surveys were consistant, the mound

had settled or compressed slightly increasing the mean depth by

approximately 20 cm. Calculation of volume differences between the

June and August surveys indicated that the volume loss due to this

compression was 1700 m3.

A survey of the southern site was also run on August 7,

1979 which likewise indicated no major differences in the spoil mound.

All transects across the mound had a slight increase of 20-40 cm

that was similar to the settling or consolidation observed on the

north mound. Calculatior of the spoil volume difference indicated

the total volume change for the entire survey was a decrease of

900 m3 or approximately half the change on the north site. There

was some indication of slumping on the north margin of the spoil

mound where a broad decrease in depth of 20-40 cm occ.rred;

In summary, the results of the August surveys indicated

no significant changes in the spoil mounds nr the capping material

could be detected. Slight settling or consolidation of both spoil

mounds did occur, however, these results were expe'ted since the

spoil mound from the 1974 dredging operation haL 3,-en stable for

several years indicating the containment potential of the disposal

site.

A second post-disposal survey was conducted on the southern

site on November 7, 1979 (Figure 10). The results of that survey

showed a major change in the topography of the spoil mound resulting

from the loss of approximately 10,000 m3 of spoil from the top of

the mound. Vertical profiles across the center o! the mound

(Figure 11) revealed a flat surface at 19 meters which was also

readily apparent on the contour chart.

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Although this loss of material did not expose any Stamford

spoil, further investigations were initiated to determine Lhe

causes of spoil movement and to evaluate conditions at the other

sites.

The flat topography of the spoil surface at a constant

depth suggested that wave action was most likely responsible for the

movement of material and the passage of Hurricane David through the

area on September 6 provided an energy source to create the wave

motion required. Consequently, additional work was conducted to

survey the other disposal sites and to determine the potential

stress exerted on the spoil mounds as a result of the hurricane.

Surveys were made of the north disposal site and the 1974 New Haven

spoil mound on November 15, 1979. Both of these surveys were

conducted using the same precision techniques, and both surveys

indicated that no significant changes had occurred in either mound

during the period in which the southern site was affected.

It is important to note that both the Stamford/New Haven

North and the 1974 New Haven deposit have minimum depths that are

less than the southern site, and thus should be more susceptible

to wave motion. Since these three mounds are all within a mile of

each other, on a comparatively flat bottom, it is hichly anlikely

that one site wouli experience markedly diiferent environmental

stress exerted by cJrrents or wave action than would be expected at

the other sites. Therefore-, an explanation for the loss of material

from the southern mound must account for the lack of movement at

shallower depths through differences between the pthsical and

lithological properties of the spoil mounds.

The Stamford/New Haven North and the 197; New Haven spoil

mounds can be distinguished from the southern site -)n the basis of

a surface of fine sand material which is probably thicker on the

newer spoil mound. This lithology is in sharp contrast to the

cohesive silt surface of the southern mound which is characterized

by clumps of cohesive clay interspersed within a fine silty matrix.

Movement of spoil material at the south mound could have

been caused by stress induced by tidal currents, wave motion or a

combination of both forces. There are several reasons to suggest

128
In summary, the effectiveness of capping enriched spoils

with cleaner material looks promising, but requires additional

monitoring to evaluate long term stability and recolonization effects.

The fact that both the sand and silt caps were effective in containing the contaminated spoils during the passage of a 10 year

frequency storm such as Hurricane David is a strong indication of

the potential of this proceduri.

An explanation for the selective movement of silt material

on the south site has been proposed based on the interaction of

storm waves resulting from Hurricane David and the roughness parameters of the cohesive New Haven spoils. The implications of these

conclusions are important to future disposal and/or capping operations.

Consolidated, cohesive spoils are common in the New England area,

and clamshell dredges which preserve the cohesive nature of the

spoils must be used to reduce suspended load and spreading of

spoils at both the dredging and disposal sites. Consequently, while

these properties aid in reducing the area of coverage, most spoil.

mounds will have surface roughness comparable to the New Haven south

site after disposal. These features have been observed at the

New London site, but the cohesive clumps have broken down over a

period of time primarily due to biological activity, but also as a

result of fracturing and erosion (Stewart, 1979 personal communication).

From the results of this study, it is apparent that the

stress created by the roughness factor associated with these clumps

under storm wave conditions is more important than the depth of

the spoil surface, the strength of currents or the cohesive nature

oi the sediment in determining the stability of spoils. The

occurrence of a major storm such as Hurricane David, before the

surface of the spoil mound has been smoothed by natural forces thus

creates a potential for large scale erosion and transport of material.

Future capping operations with silt, might therefore, consider methods to produce a smooth spoil surface at the conslusion

of the dumping procedure. Additional work is needed to determine

129
if these smoothing procedures t.re in fact necessary and to more

accurately evaluate and predict the recurrence of the effects

observed at the New Haven south site. The problem of spoil

stability is being addressed to some extent under the DAJOS program

through a combination of bottom turbulence and spoil erosion studies.

however, the phenomena observed at the Central Long Island Sound

Site emphasize the importance of monitoring disposal areas and of

understanding the interaction of the energy regime with spoil

material.

OTHER CAPPING PROCEDURES

In addition to the capping operations recently completed

in Central Long Island Sound, several proposals for capping of contaminated spoils are presently being corsidered or are currently

underway. The dredging of Norwalk Harbor, Connecticut includes

two specific capping procedures in the operation plan. Approximately, 1500 m3 of sediment contaminated by a chemical spill of

napthaleen and nitrobenzine will be placed in a pit dredged from

the adjacent channel area and covered with cleaner material from

other sections of the channel. This procedure, which will be closely

monitored by EPA Region 1 representatives, should isolate the contaminated spoils without requiring transport of the material thereby

reducing the exposure time of the material to the atmosphere and

the chances of an accidental dump or spill.

Approximately 20,000 m3 of Norwalk material which is

considered Class III material under Connecticut's spoil classification

program will be transported to the Central Long Island Sound disposal

site, deposited at a new taut-wire buoy position and capped in a

manner similar to that described earlier with additional clean

dredge material from Norwalk Harbor.

Ct:rent disposal of PCB enriched material from the New YorkNew Jersey area which is taking place at the taut-wire buoy placed

in the Mud Dump is slated for capping with cleaner material in the

near future. Management and monitoring of this operation is under

130
control of the New York District of the Corps of Engineers. Although

this operation has many aspects in comaon with the capping procedure

"hat took place in Long Island Sound, there are several differences

that should be considered in developing this management and monitoring

program:

0 The volume of material to be covered is significantly

larger, therefore, correspondingly larger volumes of

suitable capping material must be identified and dredged.

0 The disposal site is deeper, which combined with the

larger volumes of material will expand the areal extent

of the spoils to be capped. Therefore, some mechanism

must be provided to monitor and control the capping

operation to insure coverage.

0 The disposal site is exposed to more severe wave action

than the Long Island Sound Site and therefore, the spoil

mound should be only as high as necessary to provide an adequate cap and should be as smooth as possible to reduce

the stress exerted by wave action.

All of these considerations can-be readily accomodated

through implementation of a reasonable management plan centered

around precision navigation control of the capping operation.

Furthermore, a monitoring effort oriented toward evaluating the

stabJ!ity and containment characteristics of the deposit, and biological parameters beyond the margins of the mound should insure

that overall environmental impacts are minimal.

Another approach to capping and containment of contaminated

spoils has been proposed by Dr. Henry Sokuniewic: and others from

the State University of New York at Stony grook. This procedure

wuld utilize existing submarine burrow pits resulting from sand

mining in outer New York harbor as containment sites for contaminated sediments followed by isolation of the spoils through capping

with sand of similar lithology to the surrounding area.

Several favorable aspects to the use of these burrow pits

as defined by Dr. Bokuniewic2 include:

* Many of these pits have demonstrated an ability to trap

fine sediment, and therefore, should exhibit cliaracteristics

of containment sites.

131
Filling of the pits and capping of the spoils would remove

potential zones of anoxic conditions and would rcduce the

effect these deep holes might have on wave energy refraction.

* Filling of pits would most likely permit additional mining

to be accomplished without drastically altering the ambient

conditions in Lower New York Harbor.

* The location of the pits near the area to be dredged makes

them economically attractive.

However, before such a procedure can be made operational

several environmental parameters must be assessed; most important

of these is the stabi)ity of the contaminated sediment deposit in

the burrow pit prior to and after disposal of the capping material.

This concern is w-rrsnted due to the shallow ambient bottom

(approximately 4.5m) in the area and the average depth of the pit

which is generally less than 15 meters. Therefore, any deposits in

these pits would have surface depths on the order of 10 meters and

be susceptible to extensive wave action. Data on existing sediment

lithology indicate, however, that silty deposits do exist in these

pits at depths of 9 meters, thus suggesting containment is possible.

Obviously, contaminated spoils should be capped as soon as possible

to reduce the potential for dispersion.

Once deposited, the sand cap should not be sub)ect to

erosion, since comparisions of bathymetric surveys over a period

of years have shown only minor changes in the overall topography nf

the area. There will, however, always be an inherently unstable

condition when dense sand is placed over les dense mud, and it is

possible that deformation and sinking of the sand cap might occur.

The conditions causing this deformation and the rate at which it

might occur have not yet been fully evaluated.

COSTS ASSOCIATZW WITH CAPPING

The additional expenses required to conduct a capping

operation are directly related to the availability of suitable

capping material. The operating costs associated with installation

of taut-wire buoys or use of precision navigation systems to control

the dumping operations are quite small in terms of the overall project costs. Therefore, if suitable capping material is available

132
in an area that must be dredged as part of the project being considr.rcd

or associated with other projects, then proper management of the

dredging and disposal operation can produce a capped deposit at very

little expense.

H-t-ver, if additional dredging must be done to provide

capping material the costs will increase substantially. On the

Stamford/New Haven operation, approximately 30,000 m3 of contaminated

material were capped with sand, using the hopper dredge ESSAYONS for

approximately $140,000. Since it was necessary to dredge this sand

to open the outer channel of New Haven harbor these cost did not

constitute an addition to the program. However, they do indicate

the expenses involved for additional dredging. It should be

remembered that it may be necessary for the volume of the cap to

be substantially greater than that of the contaminated material,

and therefore, costs for dredging this cap could be more than the

initial operation.

SUMMARY

Under certain conditions, the use of uncontaminated dredge

material to cap contaminated sediment appears to be an operationally

feasible, cost-effective and environmentally sound method for

disposal in the marine environment. Although additional management

and operational controls are required to conduct these procedures,

they are neither expensive nor complicated and are certainly within

the capabilities of todays dredging and disposal technology.

The operational feasibility of the technique has been

demonstrated at the Central Long Island Sound site, and its application to deeper waters on the shelf is currently being accomplished

through the procedures at the Mud Dump $J•2 in New York Bight.

Although initial indications concerning the environmental considprations of capping are favorable, continued monitoring must be conducted to insure long term effects such as sand/silt instabilities,

bioturbation, storm effects, etc. do not reduce the effectiveness

of the cap in isolating contaminants from the environment.

133
AD P 002 399

STUDIES ON CAPPING OF CONTAMINATED

DREDGED MATERIAL BY THE NEW YORK

DISTRICT, CORPS OF ENGINEERS

D.J. Suszkowski

U.S. Army Engineer District, New York

Regulatory Branch

26 Federal Plaza

New York, N.Y. 10278

ABSTRACT

"\ The sediments in New York Harbor are contaminated with a

wide variety of chemical constituents. Results of testing conducted

in accordance with the EPA Ocean Dumping Criteria by several permit

applicants in 1979 indicated a bioaccumulation potential for PCB in

the marine worm being tested. Approximately 650,000 cubic meters of

material dredged from the projects were precision dumped at a tautmoored buoy located in about 27 meters of water in the Atlantic Ocean.

The deposit was then capped with approximately 1.4 million cubic meters

of uncontaminated dredged material in an attempt to isolate the contaminated

sediments from the marine ecosystem. Studies were initiated to determine the

stability of the capped mound and the biological effectivenes' of the cap.

An additional study was initiated to determine a unique chemical signature

for the disposal sediments such that the burial location of the contaminated

sediments could be identified and subsequently monitored if necessary. The

studies are all presently ongoing with final results due in early 1982,

INTRODUCTION

Approximately 8 million cubic meters of sediment must be removed from

New York Harbor each year in order to maintain safe navigation within the Port.

Historically, most of the dredged harbor sediments have been deposited at an

offshore site in the Atlantic Ocean known as the 'Mud Dump." Currently, this

disposal option is the only one available for the disposal of large volumes of

dredged material from the Harbor.

134
Because of the large volume of waste discharged into New York Harbor,

the sediments are repositories for a wide variety of contaminants. Sediments

proposed for ocean dumping must satisfy the requirements of the EPA Ocean

Dumping Criteria. When sediments are suspected of possible contamination,

they must be subjected to rigorous chemical and biological testing. Suszkowski

and Mansky (1) have described the testing protocol and have summarized the results of bioassay and bioaccumulation testing conducted for the New York District.

In 1979, routine bioaccumulation testing was implemented by the New York

District. Applicants for Dept. of the Army permits to ocean dump dredged

material were required to submit the results of bioassay and bioaccumulation testing. Six applicants in 1979 submitted test results that showed no significant

toxicity, but did show a bioaccumulation potential for PCB. The potential for

PCB bioaccumulation was evident in only one of the three test organisms, Nereis sp.

(a marine worm). PCB concentrations in the control animals for each of the te ts

were undetectable at a detection limit of 0.025 ppm. PCB concentrations in the

test animals ranged between 0.17 and 0.34 ppm for the six dredging projects.

The test results prompted considerable scientific debate over the significance

of the levels of bioaccumulation shown. The debate caused serious delays in the

permiting process. One of the permit applications involved the dredging of the

Passenger Ship Terminal in New York City. The delays were threatening the admittance of the Queen Elizabeth II into her berth in the Harbor. This situation

attracted considerable press and radio coverage along with intense political

interest.

CAPPING LOGISTICS

Since an ocean dumping alternative was the only available disposal option for

the dredged material in question, the Federal agencies involved in the sc•aintifýic

revie% of the bioaccumulation data during the regulatory review process came to a

concensus that an attempt should be made to isolate the material from the I

marine ecosystem. This was to be accomplished by capping the contaminated deposit

with appropriate uncontaminated sediments. The capping exeroise was based upon[ two

premises: (1) that the capped mound would be physically stable, and (2) that the

cap would be biologically effective in sealing off the contaminated material from

the overlying marine ecosystem.

The New York District of the Corps of Engineers accepted the responsibility!

for planning the logistics of the capping operation and developing monitoring studies.

The first step in the logistical planning was to establish an appropriate disposal

location. Currently, all ocean dumped dredged material from New York Harbor isi

deposited at the "Mud Dump" located in the Atlantic Ocean about 11 kilometers east

of New Jersey. Figure I shows the dimensions of the Mud Dump, which is a rectangularshaped area having borders of approximately 1.9 and 3.7 kilometers in length. Since

135
20 3

NW NE

25

)A 20 SN"N

BUOY

301

25

~AA

A "MD"'

BUOY

SW SE

0 6000 12000 M

I 1 1 30

CONTOUR INTERVAL = 5M

Figure 1. Boundaries of the Mud Dump and buoy locations

133b
TABLE 1. QUANTITIES OF DREDGED MATERIAL REQUIRING CAPPING

Quantity

Project (Cubic Meters)

(1) Seatrain 70,000

(2) Port Auth. of N.Y. & N.J.

Port Newark and Port

Elizabeth 89,000

(3) Port Auth. of N.Y. & N.J.

Passenger Ship Terminal 229,000

(4) U.S. Gypsum Co. 154,000

(5) Jackson Engineering Co. 106,000

(6) Monsanto Corp. 6,000

(7) Westchester County DPW ,000

TOTAL 657,000

TABLE 2. QUANTITIES OF DREDGED MATERIAL USED AS CAP

Quantity

Project (Cubic Meters)

Bronx 'iver 127,000

Westchester Creek 97,000

Ambrose Channel 1,173,000

TOTAL 1,397,000

137
""4•3

sws

.. 3

Figure 2. Accumulation of contaminated dredged material prior

to capping as derived from bathymetric surveys of

March and July 1980 (contour interval in meters)

13d
1914, the majority of sediments dumped in the ocean were deposited in the northwest quadrant of the dumpsite. A location within the dumpsite was selected

for the capping operation that avoided routine dumping activities and established a "new" disposal area which could be carefully monitored. It was decided that the

capping operation be conducted within the southeast quadrant of the Mud Dump.

To facilitate precision dumping, a taut-moored buoy, designated as the "MD"

Buoy, was placed as shown in Figure 1 within the southeast dumpsite quadrant

where water depths approximated 27 meters. A taut-moored buoy constructed by the

Naico Corporation was utilized in the capping exercise to maintain a precise

disposal location. The taut-moored buoy system consisted of a surface buoy attached

to chain and elastic Lethers to allow the buoy to rise and fall with waves and tides.

According to the manufacturer, the buoy watch circle radius was within 5% of the

installation water depth. Therefore, for the capping operation, it was anticipated

that the buoy could precisely mark the disposal point within a lateral distance ot

1.5 meters. The buoy was emplaced after a detailed bathymetric survey of the

disposal area.

Dept. of the Army permits were issued between March and June of 1980 to the

six applicants whose test results indicated a bioaccumulation potential for PCB.

A seventh permit was included in the capping operation. The permit, issued to

the Westchester County Dept. of Public Works, was included because a bioaccumulation potential for cadmium was indicated by tests performed on the grass shrimp, Palaemonetes sp. The seven permittees having material to be capped are shown

in Table 1 along with the volume of material dredged for each.

The permits were issued with conditions specifying vhat disposal take place

at the "MD" Buoy and that Corps of Engineers inspectors be aboard the disposal

vessels during each disposal event. The permittees were required to reimburse

the Corps of Engineers for the expenses of the inspectors. All of the dredging and disposal was accomplished between March and July, 1980. Dredging was accomplished with the use of clamshell or bucket dredges. The material was placed into scows

and subsequently hauled to the disposal site.

A bathymetric' survey of the dumpsite was conducted after the seven permittees

completed their work. A comparison of the March and July surveys is shown in Fig- ure 2. The deposit is skewed toward deeper water to the east. By knowing the

dimensions of the deposited sediment, a sequence of capping could then be established.

It was decided that uncontaminated sediments from three Federal dredging

projects would be utilized as capping material. The quantities of dredged material

from these projects are given in Table 2. The Bronx River and Westchester Creek

projects are relatively smill in comparison to the Ambrose Channel Project and

both were composed of fine--grained sediments as compared to sand dredged from

Ambrose Channel.

139

A_.
/'

Since the cap would have to isolate the contaminated sediments from direct

contact by marine organisms, it would therefore have to be of sufficient thickness

to prevent burrowing animals from reaching the underlying material. Benthic

organisms do have the capacity to burrow and rework sediments (2) and have been

found to be vertically mobile to depths of 60 cm. However, Pratt and O'Conner (3)

have found in Long Island Sound that most benthic species occur at depths' less than

0.1 meter. It was therefore thought that a cap of at least 0.6 meters would be

sufficient to isolate the contaminated deposit from the marine ecosystem.

Dredged material from the Bronx River and Westchester Creek Projects was

placad at "MD" Buoy. The projects were dredged with a clamshell dredge and

the material was dumped with scows. Ambrose Channel was dredged using the Corps

of Engineers hopper dredge "GOETHALS". The "GOETHALS" has a dredged material

capacity of approximately 4500 cubic meters.

Prior to the Ambrose Channel dredging, a series of disposal points was established

to ensure the placement of at least a 0.6-meter sand cap on the entire deposit.

Using the equations contained in reference (4), concerning the areal spread of

discharged dredged material from a moving vessel, 127 disposal points were established.

It was determined that two disposals were desirable at each point to produce a final

sand cap of at least 0.6 meters. During the capping operation, the "GOETHALS"

carried out 303 individual disposals.

To precisely navigate the "GOETHALS" to the disposal points, a Motorola "MiniRanger" navigational aid was used. The accuracy of this instrument at the

Mud Dump during the capping was estimated to be within 3 -meters. During

each dump, the "GOETHALS" would navigate to the pre-determined disposal point,

stop all engines, and empty all of the hoppers.

CAPPING STUDIES

A series of investigations was initiated to determine the effectiveness of

the capping operation. The logistics of carrying out the operation was the most

critical phase of the capping exercise. The logistical effectiveness could best

be determined by conducting periodic bathymetric surveys and then comparing the,

changes to actually see what transpired during the operation. The bathymetric

survey work is being conducted in-house by the.New York District.

The major concern of those who were part of the capping decision was the

short- and long-term stability of the capped mound. To address this concern, the

New York District engaged the assistance of the Atlantic Oceanographic and

Meteorological Laboratories of the National Oceanic and Atmospheric Administration (NOAA). A study effort was initiated in November of 1980 to determine the

extent to which the cap will be stable with respect to the hydraulic regime in the

vicinity of the dumpsite.

140
/

NOAA's (5) approach to answering the stability question is as follows:

a. The cap materials, the bottom roughness of the cap surface, and the

flow regime over the cap are being examined.

b. The response characteristics of the sediment cap to the flow regime

during an eight-month period are being examined.

c. Historical current meter data are being evaluated to determine the longterm flow climate.

The field program to address (a) and (b) above has been completed. Bottom

sediments were collected; flow measurements and suspended sediment concentrations were measured with in situ probes for an eight-month period; side-scan sonar

was accomplished; and a SEAFLUME was utilized to measure bottom shear stress.

Graduated rods were also placed around the capping site and monitored through

diver observations to measure erosion and/or deposition.

The SEAFLUME measurements of bottom shear stress were originally only

scheduled to be made over the cap, which is predominately sand. Though sand

is desirable as a cap in the New York Bight since it is similar to naturally

occurring continental shelf deposits, fine-grained material has advantages as capping material since it is the mist abundant type of sediment being dredged from

New York Harbor and its lower permeability may be desirable in preventing leaching

of contaminants. To evaluate the erodability of freshly deposited fine-grained

sediments, fine-grained dredged material was deposited at the "T" Buoy. SEAFLUME

measurements were then made directly over the mound.

As previously mentioned, it was thought that removing the contaminated sediments

from direct contact by marine organisms was the most important factor in mitigating

the bioaccumulation potential. Any leaching of contaminants through the cap was

thought to be of minor significance if it would occur at all. To determine the

significance of any potential leaching, mussels (Mytilus edulis) were deployed over the capping site and at several reference locations within the New York Bight and

the Harbor. The reference stations were deployed in August of 1980 while the

platform over the capping site was installed in November 1980. Weekly mussel

samples were collected for the first month after initial deployment. Bi-monthly

samples were then routinely collected at each site thereafter and until July of 1981.

Mussel tissue was analyzed for Cd, Hg, Pb, PCB, DDT, and petroleum hydrocarbons in

triplicate to allow for statistical interpretations between sites. The New Jersey

Marine Sciences Consortium is presently conducting this work.

141

/4
S//

One final study was initiated to aid in determing the effectiveness of

the capping operation. It involves the determination of a unique chemical

and/or physical "signature" for differen4 dredging projects such that the ""isignature" could be used to vertically and horizontaly identify distinct projects within a capped mound. The first objective was to establish identifying "signaturee" to differentiate contaminated material from capping material.

The second objective was to develop "signatures" for all dredging projects utilized

in the operation. The results of this study will be used to identify distinct

horizontal and/or vertical horizons and to then interpret the processes (i.e.

dumping, post-depositional compaction) most responsible for the observed profiles.

Sediment sample from each dump scow and hopper dredge load have been collected and are being systematically analyzed by the New York University Medical Center.

Core samplings of the capping site have been collected and are also being analyzed.

RESULTS

Except for a comparison of the bathym etric surveys, the work associated with all

of the other studies is still in progressi. It is anticipated that a capping synthesis

report will be available in March of 1982!.

Figure 3 shows a comparison between bathymetric surveys conducted in July and

November of 1980. The contours reflect the amount of capping material deposited

between that time period. In comparing Figure 3 with Figure 2, it is evident that

most of the contaminated sediments have been covered with a meter or more of

capping material.

CONCLUSIONS

Since all of the studies have yet to be completed, it is premature to pass final judgment on the effectiveness of the capping exercise. It is clear,

however, that technology is currently available that can facilitate precision

dumping during a capping operation. In addition, the necessary tools are

available to measure the effectiveness of, such an operation.

The prospect of capping contaminated sediments offers a unique disposal

opportunity for sediments requiring special handling. It is anticipated that

only a small percentage of sediments within New York Harbor will require special

handling in the future. Besides capping in ocean waters, the New York District

is also studying the feasibility of placement of dredged material into subaqueous

borrow pits within the Harbor. These pits were created through past sand and

gravel mining operations. The District plans to study the feasibility of placing contaminated sediments into the pits and subsequently capping them. The District's

present studies involve the use of uncontaminated sediments.

1142
12

22

A

2

22

o 1000 2000M

Figure 3. Accuiul~tion of capping material as derived from

bathymetric surveys of July and December 1980

(contour interval in m'eters)

143
If capping proves to be an acceptable disposal technique, it will greatly

enhance the overall management scheme for disposal of dredged material from

New York Harbor. A range of disposal options to handle differing qualities of

dredged material is essential for efficient port operations.

144
REFERENCES

1. Suszkowski, D.J. and J.M. Mansky, "The Disposal of Sediments Dredged from

New York Harbor," 6th Annual US/Japan Experts Meeting on the Disposal of

Toxic Substances, Tokyo, Japan, 16-18 Feb 1981.

2. Rowe, G.T., "The Effects of Benthic Fauna on the Physical Properties of DeepSea Sediments," in Deep-Sea Sediments-Physical and Mechanical Properties,

A.L. Interbitzen, ed., Plenum Press, N.Y. and London. p381- 4 00(197 4 ).

3. Pratt, S.D. and T.P. O'Connor, "Burial of Dredge Spoil in Long Island b 1,"

Marine Experiment Station, Univ. of Rhode Island(1973).

4. Environmental Effects Laboratory,,"Ecologlical Evaluation of Proposed Discharge

of Dredged or Fill Material into Navigable Waters-Interim Guidance for Implementation of Section 404(b)(1) of Public Law 92-500 (Federal Water Pollution

Control Act Amendments of 1972," Misc. Paper D-76-17, US Army Enginef- Waterways Experiment Station, Vicksburg, Miss. (1976).

5. Freeland, G.L., Young, R.A., Swift, D.J.P., Clarke, T.L. and W. L. Stubblefield,

"Stability of the Sediment Cap, Dredged Material (Mud) Dumpsite, New York Bight

Apex,"--proposal submitted to the New York District Corps of Engineers, by Atlantic

Oceanographic and Meteorological Laboratories, NOAA, Virginia Key, Miami, Fla. (1980).

145
AD POO2400

EXPERIENCES WITH THE STABILIZATION OF SEDIM ENTS

M. Nakamura

Japan Bottom Se .ment Management Association

Tsukiji 2-7-12, Chuo-ku, Tokyo

ABSTRACT

-. This paper deals with stabilizing methods for

dredged material such as (1) progressive trenching,

(2) solidification of surface layers, and (3) sand

compaction piling. To study the progressive trenching method, which was developed in the United States,

a small-scale test was carried out for dredged material from Lake Xasumigaura. The test results are

reported herein. The solidification of the surface

layer by a powdery material instead of a slurry is

discussed with examples. A new method of sand

compaction piling tested to prevent turbidity from

sea work is also reported.•--

INTRODUCTION

When planning sediment management, decisions are generally vade according to the procedure in Table 1.

Sediments are treated to improve their properties according to the

putpose of the final procedure.. The characteristics of sediments are thus

is.,proved:

(1) to attain the required soil strength

(2) to reduce the sediment volume

(3) to prevent the leaching of toxic substances

The treatment of sediment is divided into the following three principles

from the view of soil mechanics:

(1) reduction of contact pressure

(2) dewatering

(3) solidificaion

146
The relationships between the treatment and sediment characteristics

arg indicated in Table 2.

TABLE I. PROCEDURE OF DECISIONS FOR SEDIMENT MANAGEMENT

t3 7 1] 9 '14

___ .L

2 Li z 12

1. purpose of planned project

2. Natural conditions

"eological 1

opographical

terological

oceonographic| hydrological

3. social and economical conditions: compensation

lenvironmental impacts]

4. judgment on propriety of management

S. local conditions

[properties of sediment 1

site and work conditions

6• legal regulations

7. harmony with the natural scene

8. decision

9. safty control

10. amended design

11. execution

12. unknown factors

13. maintenance

supervision]

14. periodic inspection

147
TABLE 2. RELATIONSHIPS BETWEEN TREATMENT AND SEDIMENT CHARACTERISTICS

"rinciple Reduction of SolidifiContact Dewatering cation

Presurg

Attainment of

soil strength _ __ __ _

Volume reduction 0

Prevention of

leaching 0

NOTE: 0 Very effective

A Effective

Among these, the reduction of contact pressure is often applied in the

preliminary stages (before the main treatment) in order to spread out the

burdens. In this paper, three methods for stabilizing sediment are discussed:

progressive trenching, solidification of surface layers, and sand compaction

piling.

PROGRESSIVE TRENCHING

Regarding the progressive trenching method, C. C. Calhoun, Jr., presented

two papers at the previous meetings that aroused much interest in the Japanese

people concerned with sediment management. In order to determine the effects

of this method applied to our sediments, tests were assigned to our association by the Kasumigaura Construction Office (a branch of the Ministry of Construction) from Jan. to Dec. in 1980.

The test ponds, which consist of 6 compartments as Fig. 1 shows, were

made in one corner of some reclaimed land which was being filled by dredged

material from Lake Kasumigaura. The filled depth was 1.3 m.

well for groundwater level

0

trench

Si iiInvesti-

( ( <• gation

S.. . . . • - po nt

5m 7m lOn lOm 7rm 5m

Investigation

Point

_ _. .. ... __ _l.Jm ..

Figure 1. Test ponds for progressive trenching

148
The basic properties of the lake sediment are shown in Table 3. The

relationships between the volumetic change ratio and the compressive strength

are indicated in Fig. 2 and Fig.. 3.

TABLE 3. PROPERTIES OF LAKE SEDIMENT

Basic properties Mean value

Water content w 288.1 %

Sp.weight of soil particle Gs 2.62

Unit weight Yt l.18g/cm3

Sand

(74 - 2 0 0 0 u) 12.7 %

Particle

Sizes Silt (5 • l4u) 38.0%

Clay (' 5u) 49.3 %

Liquid

limit w 100.8 %

Consistency Plasticlimit Wp 37.6 %

Shrinkage

limit ws 29.4 %

Compression

Volume index Cc 0.60

Change Coefficient of

shrinkage Cs 3.94

The trench work was conducted as follows:

(1) 7 trench ditches of 1.0 m width were excavated along the longitudinal direction and one along the side wall.

(2) Progressive trenching was conducted 6 times from April to September, that

is, at a mean rate of one time per month.

(3) The trench ditches were excavated by hand from the first until the fifth

trenching and by backhoe for the sixth trenching due to the size of the

test pond.

(4) The trench depths were about 10 cm until the fourth trenching, about 30 cm

for the fifth, and about 60 cm for the sixth.

149
300

S200

410

0

20 40 60 80 100

volume change Vi/Vo x 100 (%)

Figure 2. Relationships between water content

and volume change

150 ' T ..

- I00 \v-i- • ..

(U

S 50 , -.

, , 

4.1

0 I

0.1 0.2 0.3 0.4 0.5 0.6 0.7

compressive strength qu (kg/cm )

Figure 3. Relationships between water content

and compressive strength

150
I

(5) The pitches of the trenches were 5, 7, and 10 m.

(6) The spill water from sediment water and runoff was drained from the

trenches.

(7) The water content of the sediment, its shrinkage, crust depth, groundwater level, and soil strength from a cone penetrator were measured

before and after trenching.

Test Results and Considerations

The water content of the sediment in the case of the 10-m trench pitch

decreases with time and reaches the liquid limit after about 200 days, as

Fig. 4 shows. The effects of trench pitch on decreasing rates of water content could not be determined.

wo 288.1%

So.-, -o upper layer

250 '\ -.. middle layer

Tr o-------- lower layer , ~Tr •

S200 \, Tr pitch of trench lOm

-3 \ Tr Tr trenching

~150 Tr Tr

500

10 wL 1083 % Qo_7

w 8

50

ws = 29.4 %

0

50 100 150 200 250 300

time after reclaiming (days)

Figure 4. Water content versus days after reclaiming

The comparison between measured settlements in our test and the calculated

ones from the DMRP prediction formula is indicated in Fig. 5.

151
time after reclaiming (days)

0 50 100 150 200 250 300

10 M

20 Tr

30 Tr

40 

(Tr

S60 ,

= 70-

S crust

- 90

100

110 • test result

120 -- o----<>-- DMRP prediction

'130

Figure 5. Settlement versus days after reclaiming

As the figure shows, the measurements are in good agreement. This means

that the DKRP calculation formulas for progressive trenching were verified in

our country.

We found that sun-drying dredged material requires about one year at Lake

Kasumigaura. The test results demonstrated that the dcying time would be

shortened to 7 months if the trenching method is applied in this area. Photos 1-5 show the various stages of trenching.

SOLIDIFICATION Of SURFACE LAYER

.The methods of hardening so~ft ground by solidificants such as cement or

lime can be divided into two categories: solidification of the surface layer

Sand solidification of the deep layer, both of which are often used in our

country. The former is used to attain trafficability of soft ground, while

the latter is used to provide stability for structures to be built on reclaimed land or naturally soft ground. For dredged materials, solidification

of the surface layer is often applied.

The solidifying method is generally conducted by using a slurry made of

cement or lime because it is easier to do the work in a slurried state than

a powdery one. Besides workability, the economics and the results of the

work done should also be taken into account.

152
Photo 1. 30 days after reclaiming

Photo 2. Second trenching (120 days)

153
Photo 3. Fifth trenching (200 days)

Photo 4. Sixth trenching (240 days)

154
/ r

t/

Photo 5. Coundition after raining

The advantages of the powdery state are:

(1) The required quantities of material are small.

(2) Volume expansion is also small because no surplus water is added.

(3) Material such as quick lime, which cannot be used in a slurried state,

can be applied.

On the other hand, the disadvantages of powdery materials are mcztly in

work difficulties, especially caused by:

(1) incomplete mixing

(2) dust during handling.

The powder jet injection and mixing method (DiM), which was developed to

handle these problems, is now in practice in our country.

Figures 6 and 7 graphically depict compressive strength versus mixing

ratio and mixing time, respectively.

Application of this DJM principle is now being tested in situ at a waste

disposal site under the auspices of the Tokyo City Government.

155
_______06

cry- Iý Atn

u r= .j

~ in 00 ~ 0 ' sw . c

r= % X

.- -V -a

A A

0 x

C)

41 Im (U t

________= __ _ _ _ 00

010

00e

A --

(w3/61) nb 446uaJ~s aALssaidwjoo

156
The laboratory test results, sumarized in Fig. 8, show that:

(1) In the case of cement the required quantities of powdery cement are

1/1.5-1/2 of that of slurry for the same strength.

(2) The solidified strength from quicklime is more strongly affected by soil

properties than that by cement and has a large deviation in strength,

about 2 times for the same mixing ratio.

30

25

E

S20 sample point

1 2

-o-- quick lime

Z' 5 _______cement

S-! / (slurried)

cement

(powdery)

• 10

(A 10

E

U

OY

0

5 10 15 20 25

mixing ratio (%)

Figure 8. Laboratory test results

Test Results

The site where the test was conducted is reclaimed land which was filled

with dredged material from Tokyo Bay during the last 4-5 years.

157

S*-t
The properties; of the soil at the two sample points are shown in Table 4.

TABLE 4. PROPERTIES OF THE SOIL

Sample Point, Water Con- Unit Weight Organic tent w W% yt (qCM3), pH Content ,(%)

( 124.1 1.36 7.4 12.2

185.5 1.31 8.2 15.6

The locations of the two sample points are shown below:

Ssample point•

0 area

taaea Ara

,, 2samfple point

C area

Mixing tests of solidificants were made in the laboratory before the onsite test. Cement milk in a slurried state and cement and quicklime in. a

powdery state were used as solidifants (See Fig. 8).

In the site tests on reclaimed land, for surface layers of 3-m thicknesses, powdery solidificants were injected into the soil by compressed air,

using stir vanes of 1.4-m diameters. The compressor had a delivery air

volume of 40-150 m3/hr with a maximum pressure of 5 kg/cm2. The consumption

of quicklime (under 1 mm) was 80-150 kg/m 3 . The test scenes on the site are

shown in Photos 6-8.

Fig. 9 shows a machine called the "Chemical Consolider-A," which will be

put in operation this fall. This is the first device manufactured on the

basis of the in situ test results, and it is expected to exhibit a good

solidifying function of the surface layer.

158
Photo 6. Scene of tests

Photo 7. Mixing device

159
Photo 8. Pile after execution

SAND COMPACTION PILING

The sand compaction piling method wAs developed in 1956 in our country

and has become a typical stabilization method for road banks, railroad

embankments, tank foundations, etc. It is effective for preventing liquidation of the soil in case of an earthquake. After 1964, it has been used

for sea work such as breakwaters and sea banks. In 1970, this method was

also used in successfully developing a new large-scale method (the Mammoth

Composer System) that forcibly replaces soft ground under the sea with many

large-diametered sand piles.

Sand compaction piling turns sand piles into soil, with an increase in

the relative density of the sand such as with vibroflotation for sandy soil

and an improvement in soil strength due to stress-concentrating effects for

the sand piles and sand drain effects for the clays.

The general procedure for sand compaction piling is indicated in

Fig. 10.

As the figure shows, sand piles are formed by drilling down to the required depth and then drawing otit hollow pipes. In order to ensure the

separation of sand from the pipes when drawing them out, the insides of the

pipes are kept under air pressure. In the application of this method (Dry

Method) to spa wock, the generated air blows create turbidity in the seawater.

In previous methods (Wet Method) used in sea work, no air blows were generated,

and the strength of sand piles was poor, resulting in limited utility.

In sand compaction piling (Dry Method) there is no problem with sand

strength and workability, but there is a problem with air blowing.

160
T1.L 01

, 

3L

C ~00

4J p- ~161
00 00a

•"• 4.•. . . •. " .

Figure 10. General procedure for sand compaction piling

A new method was developed in 1980 that displayed relatively good results in onsite teits conducted in north Kyushu (Fig. 11). This method has

a mechanism by whicn the insides of the pipes are saturated by water added

from the top end of the displaced sand in the drilling process and the air

pressure is controlled automatically to prevent air flow in the drawing out

process. As the water quantities and air pressure are both controllable

in this method, the sand levels in the pipes can be held safely to prevent

blowing back in repenetration.

The general scheme of sand compaction piling is shown in Photo 9, and

the three methods are compared in Table 5.

Test Results

In the tests, sand piles of 2.0-m diameters with a pitch of 2.1 m were

laid into unstable layers 4 m thick, at a sea bottom depth of 2.5 m and a

seawater flow of 0-0.05 m/sec. The investigation point of turbidity is

shown in Fig. 12.

Fig. 13 shows tests results for the measured values of turbidity at the

layer 0.5 m below the surface water at points -. The degrees of turbidity

were 0-3 ppm for wet systems with a slurry material, 9-30 ppm (max. 60 ppm)

for dry systems with a powdery material, and 3-8 ppm for the new system.

The degree of turbidity for the New Method is about 1/3 of that for the

Dry Method.

162
*800

Sand level meter hollow pi e

a~ir. - device for suppling water

sauae andcop iq

Figure 11. Mechanism of new method

Photo 9. General scene of sand compaction piling

163
CU

0 -u

30. 41

28

41' 0 LA-

- a) 41 - S ". •

i ~C (U-i~ 000

0 4 J

441

0 O>

,-6 41 C

La

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164 "I- 0 II 

164J

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500m.

150m

90M

40m

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0..

0.50

-2.5m 0.50

,=O.5(t/m3 ) 0

Silt C =0.14 Z (t/m 2 ) - Tidal current

-6.5m N-value 0

0

,F

Figure 12. Investigation point of turbidity

The generating rates of turbidity were obtained as follows:

Wet Method 14.1 g/sed

Dry Method 42.6 g/sec

New Method 21.5 g/sec

The rate of turbidity generation with the New Method was about '/2 of

that with the dry method. From these data, it was demonstrated that the new

method with water addition has in advantage in regards to turbidity.

165
100

30 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Dry Method

E 10

S 5 Ne% Method

S~Wet Method

0.3

.5

0.3

0.2

A I•m B I•m C I•m D I• E

investigation point

Figure 13., Weasured values of turbidity

166
CONCLUSION

Several new methods for stabilizing sediments are reported herein.

These tests were carried out at a field site to improve the existing

conventional methods. These new methods are not yet in practice, but are

expected to exhibit an improved function in practical application.

REFERENCES

Calhoun, C. C., Jr. "Densification, Treatment, and Management of Dredged

Material Disposal Areas," Management of Bottom Sediments Containing Toxic

Substances-Proceedings of the 3rd US-Japan Experts Meeting, 1977.

Calhoun, C. C., Jr. "Management of Containment Areas to Promote Dewatering

and Solidification," Management of Bottom Sediments Containing Toxic

Substances-Proceedings of the 4th US-Japan Experts Meeting, 19i8.

Chida, S. "Development of Powder Jet-Injection and Mixing !lethod," Bridge

Engineering, Vol 17, No. 5, 1981 (in Japanese).

167
>AD P002401

PCB CLEANUP ACTIVITIES ON THE UPPER HUDSON RIVER

I. G, Carcich, J. Tofflemire

Bureau of Water Research

New York State Department of Environmental Conservation

Albany, New York 12233

INTRODUCrION

In the fall of 1979 at a similar gathering in New Orleans, I reported

that the Hudson River was contaminated with polychlorinated biphenyls (PCBs).

Unfortunately, the Hudson River remains contaminated with PCBs and very

little has been done to correct this problem. A summary of the distribution

of residual PCBs in the Hudson River Basin is presented in Table 1.

Anticipating that Federal funds would become available to New York State

for the removal of PCB-contarinated sediments, engineering efforts were continued in an attempt to narrow down the dredging systems selections and to

finalize the design report for the PCB containment site. i

At the same time, scientific studies were also continued to focus on

refining the extent of the PCB contaminatiun and to evaluate the full impact

of the PCBs on the ecology of the river.*-

DISCUSSION

In October 1980, Congress authorized the expenditure of wastewater

treatment construction funds already allotted to New York State for the

purpose of implementing the "Hudson River PCB Reclamation Demonstration

Project." Due to the Federal involvement in the funding mechanism, the Environmental Protection Agency (EPA) became the lead Agency as required by

the National Environmental Protection Act and prepared an Environmental

Impact Statement (EIS). The!EIS was to evaluate more fully a number of

alternatives previously presented in a number of technical papers and re-

(1,2,3 ports.I' '3 The major alternatives were:

1. No action

2. In-river detoxification

3. In-river contamination

168
TABLE 1. DISTRIBUTION OF RESIDUAL PCBs IN THE HUDSON RIVER BASIN

Estimated Estimated Calculated

Total PCBs Scourable PCBs Loss Rate*

Area kg kg kg/yr

River sediments

Remnant deposits 63,500 20,400 3,900

Upper Hudson River bed

(Ft. Edward damsite to Troy) 136,000 44,450 2,600

Lower Husdon River bed

(Estuary-Troy to New York

Harbor) 91,000

Dredge spoil areas

(Upper Hudson) 72,600 77

Landfills and dumps

(Upper Hudson) 240,000 365

Biota

Lower River 91-910 0

Total 603,300

* Does not include volatilization. (Based on April 1978 Data)

4. Complete or partial dredging with upland disposal

5. Remnant deposits evaluations

6. Various dredging and transport systems

7. Control of river flow, etc.

These major alternatives were evaluated for the short- and long-term

impacts ,on the upper and lower Hudson River drainage basin and its inhabitants. The primary and secondary impact assessment objectives are summarized

in Table 2. The major finding of the EIS(4) were as follows:

1. Disposal of PCB-contaminated dredged sediments in a secure

encapsulation site would provide a much higher standard of protection of the

health, safety, and welfare for the public.

169
TABLE 2. PRIMARY AND SECONDARY IMPACT ASSESSMENT OBJECTIVES

A. Public Health

1. Protection of downstream water supply

2. Protection of groundwater in the area of the containment site

3. Reduction of PCB volatilization from river bed/bank, and remnant

deposits into the air

4. Reduction of containment site volatilization

5. Reduction of exposure through the ingestion of food

B. Fisheries

I. Permanent reopening of the commercial and recreational fisheries

2. Protection of endangered species (shortnosed sturgeon)

3. Reducing the bioaccumulation of PCBs through the food web

4. Protection of wetlands

C. Maintenance Dredging and Navigation

I. Mitigation of future maintenance dredging and disposal problems in

the upper Hudson River as well as the estuary

2. Maintenance of a navigable waterway serving transportation needs of

the upper and lower Hudson communities

D. Agriculture

Protection of livestock and their food sources through:

1. Reduction~of river bed/bank and remnant deposit volatilization

2. Reduction of containment site volatilization

3. Protection of groundwater in the area of the containment site used

for dairy industry purposes

E. Other Impacts

1. Evaluation of impacts of future hydroelectric dam construction and

usage

170

, /

/
2. The proposed encapsulation site is environmentally sound for

the indefinite storage of PCB-contaminated sediments, and that the storage of

these PCB-contaminated sediments does not present a long-term adverse

environmental impact to the surrounding area.

3. The proposed dredging operation will not have significant adverse effects on the surrounding area nor on the ecology of the Hudson River.

4. Removal of large quantities of PCB-contaminated sediments

should improve the rate of recovery of the Hudson River.

5. The removal of PCB-contaminated sediments will also reduce the

major risk of contaminating downriver water supplies; damaging public health

due to volatilization; and posing public health threats due to consumption of

contaminated fish.

Dredging/Transport Systems

rpr(5)

On September 1980, a report prepared by Malcolm Pirnie Engineers was

submitted to the New York State Department of Environmental Conservation

further evaluating the various dredging/transport systems. These systems

were evaluated based on technical, environmental, and economic feasibility of

removing PCB-contaminated sediments from the hot spot areas in the upper

Hudson River.

Three major systems were evaluated: clamshell dredging, mechanical unloading; clamshell dredging, hydraulic transport; and hydraulic dredging,

hydraulic transport. The clamshell dredging, mechanical unloading was eliminated at this stage due to the much higher costs when compared to the other

two systems. The other two systems proved feasible for the removal of the

first 20 hot spots located nearest the proposed encapsulation site. A summary of the two systems is presented in Table 3.

Even though both systems are equal in costs, the PCB losses for the

clamshell dredging, hydraulic transport are greater than for the hydraulic

dredging, hydraulic transport. It is estimated that the remcval efficiencies

of hydraulic dredging should be 95.9 to 97.5 percent versus the 90.9 to 94.2

percent for the clamshell dredging.

The major difference between the two dredging systems is the treatment

plant required at the encapsulation site. The hydraulic dredging will require a 10-MGD treatment system as compared to only a I-MGD system with recycling for the clamshell dredging, hydraulic transport.

Once the removal systems were evaluated and narrowed down to two, a

design report(6) for the encapsulation site was finalized and submitted by

Malcolm Pirnie, Inc. This report defined the desigin, construction, and

operation procedures for the containment of Hudson River PCB-contaminated

sediments. Plans and specifications as well as contract bids could now be

prepared based on the concept presented in this report.

171

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$4 - ,

17
Design Concepts

The design concepts were based on a site capacity of approximately

1,800,000 cu yd. This material would contain 236,000 lb of PCB at an average

concentration of 74 pg/g. A sumary of the quantities is presented in

Tcble 4.

TABLE 4. CONTAMINATED MATERIAL QUANTITIES FOR DISPOSAL AT CONTAINPENT •ITTF

Volume PCB

cubic yards pounds

Thompson Island Pool

and Above Lock 7

(Hot Spots 1-10) 645,500 105,800

Remnant Deposits

(Areas 3 & 5) 212.500 41_20_

Subtotal, 1st Year 858,000 147,000

V Lock 2 through Lock 6

Pools (Hot Spots 21-40) 807,200 64,100

DOT Spoil Areas

(Area 13 & Site 212) 149,400 25_,600

Subtotal, 2nd Year 956,600 89,700

Total 1,814,600 236,700

Due to the limited funds approved by Congress, the PCB Hudson River

Reclamation Demonstration Project had to be rescoped. Approximately two

thirds of the funds required to complete the entire project was approved;

as a result, only a limited number of hot spots could now be removed. This

reduced scope of %ork required a complete redesign of the containment site

as shown by Figures 1 and 2.

The encapsulation site consists of various components that include the

actual containment a~ea for PCB-contaminated sediments, a roughing and storage pond, a surge pond, a flocculation basin, and a settling basin. The containment area consists of approximately 63 acres and is designed for the

long-term storage of PCB-contaminated sediments. This material will be

surrounded by impermeable clays with the hydraulic conductivity of

3 x 10-7 cm/sec. At least 10 ft of clay will te used at the bottom and

sides and at least 18 in. of clay for the cap (Figure 3).

The roughing and storage pond is designed to minimize upsets in the

treatment units as well as to provide additional settling once the main

173
4.0

4)

0

01

1744
Figure 2. Containment site for rescoped project

containment area begins to fill up. The pond consists of 12 acres with a

340,000-cu-yd capacity. At the conclusion of the project, all of the PCBcontaminated material will be relocated within the main containment area of

the encapsulation site.

The surge pond is a 24-acre area with an effective voiume of

49,000 cu yd. Its main function is to buffer the flow of the treatment

units from surges caused by recycling ptuping demands.

The flocculation and settling basins are to permit the treatment of the

return wateŽr by means of cationic polyelectrolytes as coagulation aids. The

settling basin is designed for an overflow rate of 350 gal/day/sq ft. Likewise, these two basins are to be used only for the duration of the dredging

operation. Afterwards, the two basins will be leveled and graded.

Operational Procedures

Thus far, the various compor..nts of the upland containment system have

175
I °

41

0

0

C6

17

0

I 0=

/

j '4

176
been described. A most important aspect of this project is the actual operational procedures to be used to maximize the PCB removal efficiency and

to minimize the impact of the operation on the surrounding areas.

PCB volatilization, storm water control, site closure, leachate collection

and control, effect on groundwater, and PCB mass balance are the major components associated with the operation of the containment site. The PCB volatilization issue is of major concern to the surrounding community. During dredging, there is a potential for PCB losses at the dredge slurry inlet pipe,

at the turbulent zone of the outlet weir, and at the bulk transfer areas of

the containment, roughing and storage, surge, and water treatment units. A

sunmary of predicted losses, including those due to volatilization,

is given as Table 5.

TABLE 5. PCB LOSSES: HYDRAULIC DREDGING THE FIRST YEAR; CLAMSHELL DREDGING

WITH RECYCLE THE SECOND YEAR

Pounds PCB

First Year Second Year Total

Lost in Dredge Plume 2,100 2,600 4,700

Missed During Dredging 2,100 3,200 5,300

Volatilization Losses

Containment Area 83 38 121

R&S Pond 33 17 50

Surge Pond 0.5 0.5 1.0

Treatment Plant 0.2 0.2 0.4

Remnant Deposits 10 -- 10

DOT Spoil Areas -- 10 10

Treatment Plant Effluent 160 20 180

Total (Rounded) 4,490 5,890 10,380

The construction staging, including the closure plan, can best be described as one that ensures the least amount of PCB being lost to the environment. Figure 4 presents the various stages of construction. This plan incorporates the numerous environmental concerns as well as avoids unnecessary

excavation beyond that required to contain the PCB-contaminated sediments.

Public Participation Program

We were mandated by Federal regulations to establish a public

177
meeutAreas

?rmlamosa s .....

water Pa

KTREN SEAMS: STAGE 3 -sEOlo TEAS NEiIIII

fledged laterial7

lagr........... ,

37*61 4 - VAcusrgug SIAlE 5 FINAL CUaavc

C401tratlu~ noat !a use

Figure 4. Containment Site Construction staging

178
participation program that had its major objective in establishing a public

(7) information plan

This program had to encompass the entire Hudson River drainage basin

from New York City to Fort Edward, New York. The public information included public meetings, newsletters, press releases, brochures, technical

reports, meeting with various public interest groups, public hearings, etc.

In addition, a Citizen Advisory Committee was organized with representatives

from the upper, middle, and lower Hudson River areas. An extensive and expensive campaign was conducted in order to identify the members ot the

Committee.

The first meeting of this Committee was held in March 1981, and it has

continued to meet on a regular basis. The Committep has reviewed various

project material and has made numerous recommendations on important issues.

The Committee has proven to be an effective tool in providing accurate information to the public sector, and it has also made valuable impacts in

identifying various concerns that could be alleviated by minor modification

in the implementation procedures of the project.

CONCLUSI ONS

Since 1979 we have not removed additional quantities of PCBs from the

hot spot areas. However, a funding mechanism has been established with the

help of the U. S. Congress. The dredging systems have been refined to the

extent that only two dredging options have proven to be technically, environmentally, and economically feasible.

Additional scientific and engineering efforts have also produced a plan

capable of containing PCB-contaminated sediments in an environmentally safe

encapsulation site. Extensive monitoring efforts will prevent PCB contamination of the surrounding areas, and will assist in the efficient operation of

the disposal site during the actual river dredging.

We are still awaiting the final approval of the Environmental Impact

Statement and a ntumber of State and Federal permits. These final actions

are expected to be completed within the next two to three months, and construction of the encapsulation site is erpected to begin in May 1982.

179
REFERENCES

1. New York State Department of Environmental Conservation. 1979. "Hudson

River PCB Study Description and Detailed Work Plan, Implementation of PCB

Settlement," Technical Report No. 58, New York State Department of Environmental Conservation, Albany, N. Y.

2. Malcolm Pirnie, Inc. 1978. "Dredging of PCB Contaminated River Bed Materials - Upper Hudson River, N. Y.; Feasibility Report, Volume 1, 2, 3,

and Data Base," White Plains, N. Y.

3. Carcich, I. G. and Tofflemire, T. J. 1979. "Distribution and Concentration of PCB in the Hudson River and Associated Management Problems," New

York State Department of Environmental Conservation, Albany, N. Y.

4. U. S. Environmental Protection Agency. 1981. "Draft Environmental Impact Statement of the Hudson River PCB Reclamation Demonstration Project,"

New York, N. Y.

5. Malcolm Pirnie, Inc. 1980. "PCB Hot Spot Dredging Program.Upper Hudson

River - Dredging System Rep. t Program Report No. 2," White Plains,

N. Y.

6. Malcolm Pirnie, Inc. '980. "Design Report - PCB Hot Spot Dredging

Program Containment Site," White Plains, N. Y.

7. New York State Department of Environmental Conservation. 1981. "Public

Participation Wrrk Plan for the Hudson River PCB Cleanup Project," New

York State Department of Environmental Conservation, Albany, N. Y.

180
AD P 00240 2

PRODUCTIVE USE OF CALCINED SEDIMENT

(Calcination of Sediment for an Artifical Aggregate)

Masao Shimoda

Japan Bottom Sediment Management Association

No. 15 Sankyo Bldg.

No. 7-12, 2-Chome, Tsukiji, Chuo-ku,

Tokyo, Japan

ABSTRACT

-.. In the case of sediment removal, the problem of

how to discharge the dredged material is very important. The most popular methods are to dump it in

water or on land.-However, since this has environmental impacts, it is now being restricted by ddministrative limitations. Therefore, current demands are for measures that have no adverse effects

on the environment. The idea of finding a productive use for dredged material has grown from

such demands. As one of these, the calcination of

sediment for artificial aggregates seems feasible.

To investigate its feasibility, a calcination test

was carried out on dredged sediment from Lake Suwa

in Japan. This paper reports those test results.Z•--

JNTRODUCTION

The purpose of calcination is to produce artificial, heavy aggregates instead of natural ones from rivers. The major processes of manufacturing aggregates from calcined sediment are drying, granulation or pelletizing, and

calcination. The calcination in this study was done in a rotary kiln at a

temperature of 1150-1190*C. The properties of concrete made with these aggregates were examined in comparison with river gravel. The test results

demonstrated that the compressive strength of the concrete made of artificial

aggregates was the same or a little higher than that of normal concrete.

181
MANUFACTURE OF ARTIFICIAL AGGREGATE

Chemical Composition and Properties of the Material

Chemical and Mineral Compositions

The results of chemical analytiis and X-ray diffraction analysis of the

sediment in Lake Suwa are listed in Tablz I and Figure 1. The ignition

TABLE 1. CHEMICAL COMPOSITIONS AND MINERAL

COMPOSITIONS OF LAKE SWA SEDIMENT

ig. loss SiO' A20 Fe20 CaO MgO Na0 K20 Total Mineral

i 2 2 3 2 3 2 2 composition

15.9 46.8 20.2 7.9 3.1 1.8 1.52 1.16 98.38 Quartz

Feldspar group

-- 56.8 24.5 9.6 3.8 2.2 1.8 1.3 100.00 Kaolinite

Cristobalite

X -raw Diffraction

Dotectwr Gigerllex

Vo0la09e 40 kV

C urrent 30 mA

a e Quartz

0: Feldspar gnoup

a a I: Cristobbahte

0: Kaolnite

0 a a 0&

10 20 30 40 50 60

29 (deg) CuKa

Figure 1. X-ray diffraction patterns of Lake Suwa sediment

loss amounted to about 16% indicating that this material. contained a lot of

organic substances and other combustiblh or decomposable components. The

proportion of each component, as percentages, to the ignition loss residue is

shown in Table 1. Figure 2 is a Riley diagram in which these values are

plotted. Riley stdied the effervescent properties of shale, clay, and other

minerals, and pointed out that a clay having a composition surrounded by the

solid line in Figure 2 tends to effervesce when ignited. This mater~al may

be considered suitable as the raw material for the manufacture of lightweight

aggregates because of the large amount of organic substances contained and

182
SiOz:100%

Lake Suwa

sediment

A1203: 50% Fe203.CCOIMgO

÷ Na 2O+K20: 50/%

Figure 2. Chemical composition of Lake Suwa

sediment in a Riley diagram

its chemical composition, which corresponds to the range specified by Riley.

As a mineral, this material consists mainly of quartz, cristobalite, the feldspar group, and kaelinite as a clay mineral.

Thermal Properties as Measured by DTA and TGA

Figure 3 shows the differential thermal analysis (DTA) ind thermogravimetric analysis (TGA) measurements for this material. The DTA curve shows an

endothermic peak near 100*C due to dehydration, an exothermic peak at about

3001C ascribable to the combustion of organic substances, and an endothermic

peak near 480*C due to structural changes in clay minerals. The TGA curve

also shows a significant weight loss near 300*C.

Experiments on the Manufacture of Aggregate

Manufacturing Process

The a~gregate manufacturing process consists of the following steps:

sediment collection, drying, pulverizing, addition of water, granulation,

drying of granules, calcination, and cooling.

183

7/

- ' - ,., . - -Y
! ~/ /

/ 7 /

/ / S/

• TGA

1 Base line

_-c

Rate of temperature nse:

T• D DTA 10C / min.\inair

0 200 400 600 800 low

Temperature (oC )

Figure 3. Differential thermal analysis curve and

thermogravimetric analysis curve of Lake

Suwa sediment

Description of Eac h Step

Drying

The dredged sediment was sun-dried from a water content of 45% to 27-36%.

Pulverizing and Addition of Witer

The dried material was pulverized, blended, and conditioned to a water

content of 31-34% so that it could be extruded for granulation. The conditioned material is shown in Photograph 1.

Granulation

The conditioned sediment was then extruded into small cylindrical granules 10 mm in diameter and 10-15 mm in length, by means of a vacutu extruder

(Photograph 2).

184

7 .9 - •. 

0 ,a a l B l l l l ii l
t //

Photograph 1. Lake Suwa sediment

Photograph 2. Vacuun extruder

The granules thus produced are -',own in Photograph 3.

Photograph 3. Produced granules

185
Drying of Granules

The granules were air-dried to a water content of 10% or less.

Calcination

Calcination was conducted .Z a rotary kiln (cnpaci.*y: 40-60 kg/hr)

whowe 6pecifications are shown in Figure 4. Two-stage calcination was

8800mm

7000 mmIN E

S, o 368 mmn 1 328rmm

C14

OUTLET MOTOR

Figure 4. Specifications of rotary kiln

adopted to minimize extra effervescencL due to combustion of the organic

substances contained. In the first stage, calcination was carried out at

1030*C while supplying a sufficient amount of air to effect combustion of the

organic substances. In the second stage, air supply was interrupted (exhaust gaa fan stopped) and calcination was conducted at two temperature

levels: 1150-117n* and 1170-1190*C. The fuel consunrptioL (kerosene) was

about 440 liters/ton for each stage. Photos 4 and 5 show the progress of

calcination, and Photo 6 shows the final aggregate.

PROPKRTIES OF AGGREGATE

Sieve Analysis

The sieve analysis was conducted according to the method defined in

JIS A1102 (1). The results are shown in T.ble 2. The particle size of a substantial portion of the calcined aggregate was concentrated within the range

of 5-10 mm. The river gravel used in this experiment was sieved to provide

the same particle-size distribution as the calcined aggregate to ensure a

reasonable comparison.

186
Photograph 4. Feeder

Photograph S. Rotary kiln

Photograph 6. Calcined artificial asgg--gates
TABLE 2. SIEVE ANALYSIS TEST RESULTS

Clear square opening Fineness

Kind of aggregate 1 of siev i)n modules

K0 5 2.5 1.2

River gravel 0.2* 99.7 99.9 100 6.00

Calcination 1170-11900C 0.2 99.7 99.9 100 6.00

temperature 1150-1170oC 0.5 99.2 99.5 100 4.00

* Percent retained.

Specific Gravity, Coefficient of

Water Absorption, and Weight of Unit Volume

The specific gravity and coefficient of water absorption of the calcined

aggregate were measured according to the methods specified in JIS AIIIO (2),

and the weight of unit volume was determined by the method given in JIS A1104

(3). The results are listed in Table 3. No significant difference in specific gravity was observed between the two kinds of aggregate calcined at 1170-

11900C and 1150-11700C. However, the coefficient of water absorption was

18.45% for the aggregate calcined at the lower temperature, which is 6% larger

than that calcined at the higher temperature. The calcined aggregate was

lighter than the river gravel of the same particle size, its weight of unit

volume being 68% for the calcination temperature of 1170-1190C and 60% for

the temperature of 1150-11700C.

TABLE 3. SPECIFIC GRAVITY, COEFFICIENT OF WATER

ABSORPTION, AND WEIGHT OF UNIT VOLtUE

OF AGGREGATES

Test item Coefficient Weight of unit

Kind of Sp. gr. of water volume

s.......te absorption(%)) (kg/m 3 )_

River gravel 2.64 0.68 1,660

Calcination 1170-11900C 2.04 12.41 1,130

temperature 1150-11706C 1.97 18.45 1,000

Leaching Test for Toxicants on the Calcined Aggregate

The leaching test for toxicants was carried out on the calcined aggregate

according to the procedure defined in the Environment Agency Notification

No. 22. The results obtained are shown in Table 4. No toxicants were detected

by this experiment, and the calcined aggregate was confirmed to be harmless.

188
TABLE 4. LEACHING TEST RESULTS OF THE

ARTIFICIAL AGGREGATE

Name of toxicants T-Hg Pb Cd As CN Cr(VI)

The limit of detection for

toxicants in case of the

reclamation, appointed by 0.005 2 1.5 1.5 1 1.5

Environment Agency,

Japan (mig,2)

Results UD* UD UD UD UD UD

*Undetectable.

APPLICATION TO CONCRETE

Materials and Apparatus

Materials

Cement

Normal portland cement was used. Its chemical composition is listed in

Table 5, and physical properties are shown in Table 6 and Table 7.

TABLE 5. CHEMICAL COMPOSITIONS OF

NORMAL PORTLAND CEMENT

ig. SiO Ao0 Fe( so

loss In sol. 2 2 3 2 03 CaO HgO 3 Total

Normal 0.4 0.0 22.4 5.3 3.1 64.9 1.5 1.7 99.3

portland cement

JIS 5201 (.) <3.0 <5.0 <3.0

Fine sand

Fine sand collected from River Sagami was used. Its specific gravity

was 2.59, coefficient of water absorption was 2.12%, and fineness module was

3.20.

River gravel used as reference

River gravel as listed in Tables 2 and 3 was used for comparison with

the calcined aggregate.

189
TABLE 6. PHYSICAL PROPERTIES OF NORMAL

PORTLAND CEENT

It.. Fineness Setting

Specific sa ater Initial Final

Sp. &r. surface Residual content setting setting Temperature Humidity Soundness

(.zs, K) . (% m/h) (a/h) (40) W%

Normsa

portland 3.16 3,280 1.0 26.4 2-43 3-53 21 83 Good

cement

JIS >250>60 <10

5210 (5) 2,S0 3 >o Good

TABLE 7. PHYSICAL PROPERTIES OF NORMAL

PORTLAND CE11ENT

Itemr Strength (kg/CMZ)

Flow Bending Compressive

3d 7d 28d 3d 7d 28d

Normal

portland 266 32 49 70 132 236 408

cement

JIS 5210 (5) >70 >150 >300

Apparatus

A 100-1 capacity forced mixer was used.

Dimensions of Test Pieces

Compressive and Tensile Strength Tests

The size of the test pieces used for the compressive and tensile tests

was #10 x 20 cm.

Bending Strength Test

The size of the test pieces used for the bending test was 10 x 10 x 40 cm.

190
Curing and Testing Methods

Curing of Concrete

Concrete samples were removed from the forms two days after casting,

and then cured in water at 20 ± I*C to the respective testing ages.

Testing Methods

The compressive, bending, and tensile strength tests were conducted according to the methods specified in JIS A1108 (6), A1106 (7), and A1113 (8),

respectively.

Mix Proportions of Concrete

In order to determine the effect of the type of aggregate on fresh concrete and hardened concrete, mix proportions were set so that the weight of

cement per unit volume of concrete, weight of water per unit volume of concrete, and S/a ratio would be maintained constant, as shown in Table 8.

TABLE 8. PROPORTION OF CONCRETE

Quantity of material per (kg/m 3 )

Maximum Slump W/C S/a Air unit volume of concrete

Kind of aggregate size Water Cement Sand Gravel Admixture

(-) (am) (%) (%) (%)

River Gravel 10 12 50 50 5 182 350 851 867 0.875

Calcination (1170-I190-C) 10 12 50 50 5 182 350 851 670 0.875

Temperature (1150. 11700C) 10 12 50 50 5 182 350 851 647 0.875

Test Results

The test results on fresh and hardened concrete are sown in Table 9.

In fresh concrete, the calcined aggregate gave a slump 4.4-7.6% smaller

than that given by the river gravel and showed 34-48% increases in air entrainment. In hardened concrete, on the other hand, the same level of compressive strength as the river gravel concrete was obtained with the artificial aggregate calcined at 1170-1190'C, for both samples cured for 7 and

28 days; that is, the sample cured for 28 days showed a compressive strength

of 400 kg/cm2 . The concrete using the aggregate calcined at 1150-1170*C,

however, showed a compressive strength about 85% of that of the river gravel

concrete.

In the bending test, as compared with the river gravel concrete, the

artificial aggregate calcined at 1170-1190 0 C gave a higher strength for both

191
TABLE 9. TEST RESULTS OF FRESH CONCRETE

AND HARDENED CONCRETE

t item Fresh Strength of hardened concrete (kg/cu 2 concrete, ) Static Tensil. elastic

Slump Air Compressive Bending Tensile modulus

Kind of (28)

! aregate' (cm) (W) 7d 28d 7d 28d 7d 28d x 105

River gravel 15.8 5.8 256 405 42.5 50.3 24.3 26.6 3.51

(1.oo)* (1.00) (1.00) (1.00) (1.00) (1.00) (1.00)

(1170-11900C) 15.1 7.8 251 400 45.9 52.1 22.4 30.8 2.58

Calcination (0.98) (0.99) (1.081 (1.04) (0.92) (1.16) (0.74)

Temperature (1150-11700C) 14.6 8.6 219 345 42.0 48.4 22.3 21.7 2.20

(0.86) (0.85) (0.99) (0.96) (0.92) (0.82) (0.63)

* Index.

the two age groups, and nearly the same level was observed for the aggregate calcined at 1150-1170*C.

The tensile strength was about 10% nigher when the aggregate calcined

at higher temperatures was used, but was about 20% lower with the calcination

temperature of 1150-1170*C.

PRODUCTION COST OF CALCINED AGGREGATE

The quantity of sediment to be dredged for clarifying the water of Lake

Suwa amounted to about 530,000 mi3 . If a new aggregate calcination plant with

a capacity of 10 t/h (240 t/d), including a dryer, rotary kiln, power ý;cation,

and other necessary facilities is built, the production cost of the calcined

aggregate is estimated at approximately 9800 yen/t product (2200 yen/m3

sediment).

CONCLUSION

The manufacture of artificial aggregates from calcined sediment requires

no pulverizing and no bonding agents for granulation or pelletizing because

the sediment is originally made of very fine particles and has a bonding property due to the organic materials contained. Therefore, the manufacturing

processes are simpler than ones for natural rock. This is an advantage in

production costs.

The most important points regarding production are the heating rates and

the calcination temperature. These are carefully determined by pre-calcining

tests in the laboratory. In this case, the former is 5°C/min and the latter

is 1150-1190*C. It has been demonstrated that the compressive strength of

the concrete made of artificial aggregates is the same or a little higher than

that using natural aggregates.

192
This means that the calcined sediment can be applied to civil engineering

practices. It is found that the trial cost of production is not as high as

might be expected. Therefore, it can be said that the calcination of sediment

is a promising way of using resources.

REFERENCES

(1) JIS*A 1102 Method of Test for Sieve Analysis of Aggregate

(2) JIS A 1110 Method of Test for Sieve Gravity and Absorption of Coarse

Aggregate

(3) JIS A 1104 Method of Test for Unit Weight of Aggregate and Solid

Content in Aggregate

(4) JIS A 5201 Classification Standard of Tile for Exportation

(5) JIS A 5210 Hollow Clay Building Blocks

(6) JIS A 1108 Method of Test for Compressive Strength of Concrete

(7) JIS A 1106 Method of Test for Flexural Strength of Concrete

(8) JIS A 1113 Method of Test for Splitting Tensile Strength of Concrete

* JIS: Japanese Industrial Standard.

193
'AD P 0 02403

SEVERAL SOLIDIFIED SEDIMENT EXAMPLES

D. Kita and H. Kubo

Japan Bottom Sediment Management Association

2-7-12, Tsukiji, Chuoh-ku, Tokyo 104

ABSTRACT

-•. The treatment of bottom sediments by solidification has incre~sed in Japan in recent years. This

paper describes the state of the art in our country, citing some examples. The applications of this

method can be divided into four cases, which are

discussed in this paper.-<--

INTRODUCTION

Solidificatimn of bottom sediments is imilar in principle to the

soil-cement and ý,oil-lime methods in soil stabilization on land.

However, the properties of the bottom ediments and the places wtere work is

done differ considerably from work on land. Accordingly, solid-iiication of

bottom sediments is different from conventional soil-cement and soil-lime

methods in many respects such as the purposes, effects, and applications of

solidification, work execution equipment, and solidificants. This paper

describes the results of investigations and tests carried out regarding these

points.

PURPOSES AND EFFECTS OF SOLIDIFICATION

The purposes of solidifying bottom sediment are to increase the mechanical strength of sediment and to prevent the release of toxic components into

thp overiyinq water.

Incrp-c_,_f Strength

Bottom sedirnrtq possess large quantities of very fine particles, have

high water contents, and are extremely soft. Therefore, from the standpoint

of soil mechanics, bottom sediments comprise one of the worst kinds of soil.

For example, the softness of sediments is a great obstacle to work in cases

such as the following: (1) Effective use as land of the dredged sediment containment area.

(2) Hauling of dredged sediment to the containment area by dump truck.

194
(3) Utilization of dredged sediment for civil work materials such as

embankment and fill materials.

Therefore, it is extremely important to increase the strength of sediments.

Methods of increasing sediment strength are based on stabilization

methods for soft ground. Stabilization methods for bottom sediment may be

broadly divided into the three categories: sun-drying, consolidation drainage, and solidification. Of these methods, solidification is often adopted

since it makes it possible for sediments to be stabilized in a shorter time

and to a higher strength compared with the other two methods.

Prevention of the Release of Toxic Components

Bottom sediments, especially sediments at the bottom of w;.cer fronting

urban areas, often contain large quantities of heavy metals, PCB, nitrogen

compounds, and phosphorus compounds as toxic substances. When preventinq

release of these toxic substances by soliditication, the mechanism nay be

divided into physical and chemical aspects.

Physical Mechanisms of Release Prevention

When solidificants are mixed into bottom sediments, the sediment particles a.e mutually bonded together, while voids between the particles are filled to a considerable degree by hydration products of the solidificants so

that the permeabilities of the sediments are substantially decreased.

Consequently, churning up sediment particles due to the disturbance of

overlying water is prevented, while further, for practical purposes, the

contact area of sediment particles with overlying water is decreased. It is

in such a manner that heavy metals, PCB, nitrogen compounds, and phosphorus

compounds are physically restrained from being leached out from sediments into

water. It may be considered that suchi a physical mechanism is more important

than the chemical mechanism in preventing release.

Chemical Mechanisms of Release Prevention

Since cement and lime are used as solidificants, solidified sediments

show fairly high pH values, particularly values immediately after mixing

solidificants that reach 11 to 12. This rise in pH has great significance

in the chemical mechanism, with the influences being different for heavy

metals than for nitrogen and phosphorus compounds.

Heavymetals generally form hydroxides of low solubility under alkaline

conditions. This may chemically stabilize the heavy metals in the sediments.

However, the sediments are in a reductive condition and contain large amounts

of sulfur componds, while the heavy metals are in the form of sulfides. The

solubilities of these metal sulfides are much lower than those of hydroxides

of the metals. Also, there are some hydroxides of heavy metals which produce

complex ions when their pH values are higher than about 10 and become more

soluble. Further, in the case of mercury compounds, although sulfides are

extremely stable, hydroxides are unstable. In these respects, it cannot be

said that solidification will chemically suppress the release of heavy metals.

1

195
It is conceivable that when bottom sediments are dredged and oxidized

uhrough exposare to air at containment areas, the sulfides will be transformed

into sulfates, pH values will change to the acidic side, and the solubilities

of heavy metals will increase. Solidification with the objective of preventing

acidification will be chemically effective.

Most of the nitrogen and phosphorus compounds in bottom sediments, along

with carbon compounds, comprise components of organic matter in the sediments.

Generally speaking, organics in soil are decomposed into humus and soluble

organic matter under alkaline conditions. Similar phenomena have been recognized

in cases of the solidification of bottom sediments. When sediment is solidified with cement or lime, the organics in the sediment are decomposed by

alkali and a part becomes soluble so that the nitrogen concentration and COD

of the overlying water are increased. However, phosphorus compounds in

sediment react with calcium ions in the solidificant to form calcium phosphate which ir low in water solubility, and there is practically no leaching

of phosphorus. In view of tie above, in order to, suppress nitrogen compounds in sediments from being released and COD from being increased, it Will be

advantageous to use a solidificant which raises pH as little as possible.

Therefore, it cannot necessarily be said that solidification

contributes greatly to chemically preventing leaching, and it is considered

that physical release prevention effects are more significant. It should be

mentioned, however, that several varieties of solidificants containing additives to enhance chemical release prevention effects have been marketed

in recent years. In any event, further investigations will be necessary

regarding the matter of preventing leaching out of toxic substances by solidification.

APPLICATIONS OF SOLIDIFICATION

Cases in which solidication would be applied to treat bottom sediments

may be divided into the four categories as discussed below.

Case A: Bottom sediments are dredged and transferred to containment

areas where effluent is treated and then discharged. When the bottom sediments have been filled to the planned height and have settled to an extent,

they are subjected to solidification (Figure 1). The extents and forms of

solidification may be divided into the three kinds shown in Figure 2.

Figure 1. Typical diagram of Case A

196
Gd uai Muddy Solidilecl

idlivim ni sidimefi

//

/ /

(a) Solidifying surface (b)Solidifying entire (c) Solidifying entire

layer of sediment layer of sediment layer of sediment

in stripes

Figure 2. Extents and configurations of solidification

in Case A

Case 3: Sediments are dredged and solidified on the way to the final

containment area. This is an effective method when dredging by grab dredger

or suction dredger which is capable of dredging at high solids concentration

(Figure 3).

d ".. 

- Sdfymn 

0lo 

U r

rnsporn nS eadng 9 & .Utilizing reSoiidi-inq r-npi r 'tn •'quo,•y soi •c•aimed landI

Sohdd-cwt

Figure 3. Typical diagram of Case B

Case C: A part of the water body is cofferdammed and dewatered,--and,

after lowering the water level, the bottom sediments are solidified in situ.

Upon completion of solidification, the water level is restored directly over

the solidified sediment or after providing an overlay of concrete. There

are also cases when the solidified sediment is removed, after which the water

level is restored (Figure 4). This method is often applied in treating bottom

sediments in rivers.

197
Muddy "d Soi~difie Scl.fying machiue

, mmirg.-,, ernJ solidifyi 'Placing concrete over!ay -; ltoring waet lever "

"=In

Figure 4. Typical diagram of Case C

Case 0: Fottom sediments are solidified in situ

from a treatment vessel at the surface of the water

with hardly any change in the water level (Figure 5).

This method is applied at times when dredging cannot

be done and lowering the water level is difficult.

However, there are very few examples of imple- mentation of this method. The chief reasons for Sohdifyi .

this situation are the three below. Firstly, water (in situ withou

is contaminated by agitation of sediments and Figure 5. Typical

solidificant when performing solidifying work. Tial

Secondly, the solidified strength is not increased Case D

very much since part of the surface layer of

the sediments is drawn in large quantity.

Thirdl'y, adverse effects on benthos are of concern.

EQUIPMENT AND SOLIDIFICANTS FOR SOLIDIFICATION

Equipment

The equipment for solidification will differ depending on the methcd of

solidification. The equipment used in Cases A, C, and Ui described above consists of machines for solidifying ground comprised of bottom sediments.

The equipment used in Case B consists of machinery for solidifying dredged

sediments in transit to the containment area.

Solidifying Equipment for Sediment

Equipment for treating sediment generally consists of a plant for supply- ing soidificant made into a slurry by mixing solidificant powder and water

in ratios of 1:1 to 1:3 by weight, and an agitator-mixer for mixing the

supplied solidificant with bottom sediments. Agitator-mixers may be classified as ship-type (Figure 6) and crawler-type (Figure 7).

198
",,(KI t r S .04 kg/cm2

Figure 6. Example of shi5-type agitator-mixer

..... - slf) ""4irww ft

FWe~gtl of shipwi14m

-W-euo Shi of04 mochir

Figu.re 7. Example of crawler-type agitator-mixer

The ship-type equipment is a mnachine which travels on' the surface of bottom sediments forcing so•idificant slurry pumped from the solidificantsupplying plant into t7.e sedimeots. and performs agitation and mixing. The

speed of the agitating prcpeller of the ship is 40 'o 60 rpm. This type of

,aait3tor-mixer is capable of accurate travel on tV surface of even very soft

sediment, work can be executed even on water, and tne thickness of the treatment is large.

On the other hand, a crawler-type is a self-propelled machine having a

pontoon-type body equipped with extra-width treads. Solidificant is pumped

from the solidificant-slurry-supplying plants in cases similar to the shiptype, but there are cases in which solidificant is spread in the path of the

crawler-type equipment. The crawler-type cannot move abou. freely when the

bottom sediment ;s very soft, while the thickness of solidification is

app-oximately 1.5 m at mdximum. A feature of this type is easier traveling

and wf-k efficiency is good if the strength of the sediment-yround is higher

than a certain level.

Solidifying Equipment for Sediment in Transit

Equipment for solidifying bottom sediments which have been dredged and

are on the way to the containment area may be divided Into agitdtilly-blade

types, pipeline-mixer types, and bucket types.

The agitating-blade type is represented ty the pugm, ll mixer. The pipeline-mixpr type has blades attached inside a pipe, and sediment to which solidificant has been added passes through to become mixed. Fu-ther, clamshells

and backhoes are typircl of bucket type equipment.

199
Sol idi ficants

Solidificants may be divided into cement types and lime types. Since

the former are hydraulic, it is possible for bottom sediments of high water

contents to be solidified. As for the latter, quicklime or lime are used,

and, although there is a dehydration effect, the degree of solidification is

inferior to cement types. Therefore, cement type solidificants are chiefly used to solidify sediments of high water content and very weak strength.

A typical solidificant of the cement type is ordinary portland cement.

Ordinary portland cement is frequently used in solidification of bottom

sediments. Meanwhile, in recent years, in order to further increase solidified strength, cases of using special cement type solidificants with chemical and mineral compositions adjusted have increased. However, there were

many unknown aspects regarding the effects and conditions for applications

of these special solidificants.

Accordingly, comparison tests

were performed on 14 varieties TABLE 1. PROPERTIES OF SOIL SAMPLES

of cement type solidificants.

The results of the tests are

described in outline below. C" L Ok -',, ,•...I.,..'.

Fourtee.n representative So , * 5 1 S t z * f 150 1.

B......4) were used in the ,.,-.....' z ,, A4 -%'0 -,

tes¢s. "he four varieties of

soils shown in Table I were

used as soil samples.. Of the

four varieties of soil, three,.

(not including Ohtemachi) TA.-. , ._-_._

were bottom sedimentc. , . . . while 0htemachi was a co- !!--7

hesive so-.1 Pxcavated ' " - i

in a foundation project. ' * )

Chemical Compositions _ _.... ._r T=-* 

of Solidificants ,, . -

shown in Figure 8, con- *' ', -

tain CaO, SiO,, Al:01 ..-.. and SO,, and ilay be

divided into six groups ... ._______-_. __- ____

according to tVe Lon- ... _

tents of the ai)ove. . Solidificants I; to N.

contain larger amounts _ of SO, comparpd with A

(ordinary portland Figure 8. Chemical compositions of 14 varieties

cement) of solidificants

200
Relations between Varieties of Solidificants and Solidified Strengths

The unconfinei compressive str:?ngths after 28 days of curing the four

varieties of soil treated with the solidificants are shown in Figure S. It

may be seen that strengths were similar within groups of solidificants.

The group indicating high strength on the average was V, followed in order

by MII, V I, IV, 11 and U . Therefore, the relations between chemical compositions of solidificants and solidified strengths were examined, and as a

result, as shown in Figure 10, strengths were found to be considerably

influenced by the CaO and S03 contents of sooidificants. High strengths

were gained when GaO contents of solidificants were 58 to 60O, and SO3 contents 9 to 13..

UflcoMfmd C~Vw6v We"9q1tN li~et 28 devs (kqjcm2 j

L 1iii~

----- ----- -----

.. .. . .7 ---- .. 

----------.........

2041
OrBow ModWM WO& ffq11M." a q 

os

4'

-o 0

SO% oEa'df~ c~ %

Figure 10. Relations between chemical

compositions of solidificants

and solidified strengths

Examination of Solidified Strength by X-ray Diffractometer

Examples of X-ray diffraction charts are shown in Figure 11 for sediments from two location%. Both sediments showed peaks for quartz, feldspar

and clay minerals before solidification. And, after solidifying with solidificant K, pe ks not seen prior tA solidification appeared at 9.l (9.37A), 15.80 (5.61 A), and 22.90 (3.88 A). These peaks were identified as a

mineral, ettringite, whose formula is 3CaO.Al0O3.3CaSO..32H20.

As shown in Figure 12, strength has a tendency to increase as the

amount of ettringite in the solidified sediment increases. The solidificant

N, in spite of producing a large amount of ettringite, does not show very high strength, and the reason for this is not clear.

202
i Fill if

C, € II F1 -C-o-i It l

S_ _ i .'2 . 4-

_____,___ .. ____"__.. _ quantities of

•,, ettringite formed in

soiiid eiet

Figure 11. X-ray diffraction charts sldfe eiet

for sediments and and solidified

solidified sediments strengths

Examination of Solidified Strength of Scanning Electron Microscope

Photos 1 to 6 are scanning electron micrographs of Tagonoura and

Kasumigaura sediments before and after solidification. It m~y be seen that

aggregates of cement hydrate minerals are formed in the solidified sediments

with interstices filled by acicular crystals of ettringite to form bridges

between the aggregates. It may be surmised from this that formation of

ettringite, in a similar way to the formation of other cement hydrate

minerals, contributes greatly to strength gain of solidified sediment.

PihOtO. 1 Scalnninq electron mtcroqrao~h of Photo. 2 Scann~nq electr'on mnicroqjrap~h of

TaqgonouJra bott~om sediment Taiqonoura bottom sediment

(unT reated) (solidified wCth t0lidificant K)

203
Photo. 3 Scanning electron micrograph of Photo. 4 Scanning electron micrograph of

Katsushima bottom sediment Katsushima bottom sediment

(untreated) (solidified with solidificant K)

10,m .II l~ M

Photo. 5 Scanning electron micrograph of Photo. 6 Scanning electron micrograph of

Kasumigaura bottom sedirrent Kasumigaura bottom sediment

(untreated) (solidified with solidificart H)

FACTORS INFLUENCING STRENGTH OF SOLIDIFIED SEDIMENT

Various factors influence solidified strength, the principal ones being

the following:

(1) Factors regarding properties of bottom sedi'lents:

water content, grain-size distribution, organic contents

(2) Factors regarding solidificants:

varieties of solidificants, quantities Jf solidificants added

(3) Factors regarding mixing of bottom sediments and solidificants:

mixed condition

(4) Factors regarding curing:

curing temperature, curing time

Although all of the these factors are important, the mixed condition and

curing temperature are of particular importance in estimating solidified

strengths in the field from laboratory tests and designing the quantities of

solidificant added.

Accordingly, investigations were conducted on the degree of influence

the mixed condition and curing temperature have on the differences between

204
laboratory tests and field strengths, and examples of the investigation

results are described below. These investigations were carried out in the

solidification project example of Fushigi-Toyanra described later in this

paper.

Method of Testing

Specimens of SSampling sediment mixed with cement by solid,fying ship solidi- I fsý ,=.

fied soil were prepared by L mixing

the four methods shown in

Figure 13. Since samples Thorough remixingof cementwere collected simultaneous- mixed sediment with agitating

ly from a small area, all spoon I

were thought to be of the [laboratory mixing j

same properties with the ý4)

cement addition quantities

roughly identical. The

strength according to () Casting in *5cm x xlOcrn Ca3ting in 06cm xh1Ocm mold,

in Figure 13 is the strength mold , and curing at 20*C and curing in situ in field

in laboratory tests performed for 7 days and 28 days fbr i days and 28 days

in general; that is, the [aborat-ry curing J I (field curing)

strength for bottom sediment

to which solidificant had Figure 13. Four methods o• preparing

been added and was thoroughly solidified specimens

mixed and cured in a 20 0 C constant temperature room. The strength according

to (®) is the field :trength, in effect, the strength of sediment ground

solidified by solidily;ng equipment.

Influences of Differences in Mixed Condition, and Curing Temperature on i-•*" O ,

Solidified Strength l. -

The results of unconfined compres- n

sive strength tests for the methods

of (D through (A) are given in

Figure 14. Solidified *trLrngth is

highest with (, followed in order

by ,1 , and (A).

The relatiots of unconfined

compressive strengths between the cases r

(D to T are shown in Figures 15 through -

17 . From the relation between @9 and '

in Figure 15, the following is obtained:

qu - fm. fc

Y : u - m .fc 0.20 ~ 0.35 (av. 28%) I

qu - lm-lc

where , d,-

Im : laboratory mixinq

Ic laboratory curinq Figure 14. Unconfined compressive

fm field mixing strengths of solidified

fc field curing specimens prepared by

qu unconfined compressive strength four differr't methods

205
The symbol y~ expr sses the ratio between field strength and laboratory

strength, and it is suggested that field strength in this project is no more

than about 20 to 35% (average 28%) of the strength in ordinary laboratory

tests. These figures are

extremely important when

designing the addition

quantity of solidificantZ ý

in a solidification project

based on laboratory test

results. Y uII

The differencet, in mixed 31

conditions and curin¶, temper- -6

atureS greatly influence the

difference between field 4,

an aoatory strengths, and (n IL O I

a n lue st o n r is s a to th e 0 Strengi . Of Soh4 fied se di rn ntie n lab oar la ry Mtixing

degree of contribution by ai ik uiq(ff i 3,ul~C(gc 2

each factor. Figure 16

shows the influence of the Figure 15. Relations between laboratory

mixedcondiion:and field strengths

~jfl 0 041 - 0.94 (av. 67%)

qu - I

Figure 17 shows the influence of curing conditions:

5=qu - fc =0.23 - 0,67 (av. 44%)

As indicated above, field strengths, compared with laboratory strengths,

were found to be reduced to an average of 67% due to poorer mixing conditions

and an average of 44% due to a low curing temperature. The mixing condition

is affected by the configurations and rotating speeds of the agitating propellers of the equipment, mixing times, etc. Meanwhile, curing temperature is

influenced by factors such as meteorological conditions.

2

an an. 1

Riltano befani Z~r 4. I. ( A206
Curing Temperature in the Field and Its Influence on Strength

The investigations were carried out in the

wintertime during December and January, and the Tem,,eraure (1C)

surface of the solidified bottom sediments was , 10 210

oftem covered by snow. Figure 18 shows the

results of investigations of temperatures inside

the sediments in the direction of depth 4 to 5

days after solidification treatment in the field.

The temperatures in untreated ground were 11 to

13'C. On the other hand, although solidified

ground was not very much different from untreated

ground down to 20 cm from the surface, the temper- 0

ature rose to 20'C at around 50 cm, the center a

of the solidified portion, so that the temperature was 7 to 8*C higher than at untreated ' /

ground. It was ascertained that such a temperature difference continued to exist for approxi- slam of

mately one week after solidification, but , "

subsequent measurements were not made. - ...

Based on the above, it was found that the .rF4,a 5 days

field curing temperature in the vicinity of _,

the surface layer was approximately 10*C.

Thereupon, separate tests were carried out in Figure 18. Underground

the laboratory regarding the influence on temperatures

solidified strength of the difference between in solidified

curing temperature in the field (10°C) and and unsolidicuring temperature in the laboratory (20 0 C). fied sediment

The re.ults are given in Table 2. Solidified greund

strength was reduced to approximately

one half by lowering the curing temperature from 20*C to 10 0C. This agrees more Table 2. RELATION BETWEEN CURING

or less with the influence of curing con- TEMPERATURE AND SOLIDIditions, 0=0.44 (av.), described before, FIED STRENGTH

suggesting that the influence of (LABORATORY TEST)

temperature was important among curing

conditions. J

bO'C 033 0.50 ,.52 20"C 061 1,06 1.74

alrC;, ft ne- .85 2.1 #

cement 75% added

EXAMPLES OF SOLIDIFICATION PROJECTS

Sediment Containment Area in Fushigi-Toyama Harbor

This is an example of Case A. At Fushigi-Toyama Harbor in Toyama

Prefecture, an area of 70 ha has been reclaimed by filling with bottom sediments brought up by a pump dredger. This ground is very soft since it has only

recently been filled. The surface layer sediment stabilization of a portion

207
of the area, 10.5 ha, was carried out for the purpose of land use, and strips of the surface layer were solidified as part of the work. The equipment used was a ship-type machine.

P ", A SQI 4.04 ..

$A. , Lot

j... j l0..~"ov~,t 1ý4.

Figure 19. Flow of work

The flow of the work is shown

in Figure 19. The extent and

configuration of the solidifi- 35Om, cation and the strengths of - /

the sheets and nets laid are - tE'.. 

indicated "- M |1 -7 -. (,,.9qmof1.100 kgml in Figure 20.. ,. .'

The objective of the solidi- "I

fication in this project

was to secure a foothold for' h K

the manual laying of sheets and

nets and to improve work effi- E

ciency in the spreading of the "

soil. "- - /- " -: "! /'' •l' 0,n,,o 'k,,•

Properties of sediment: Water - -Good ... I- W.d 

Wawa • ,not "Id3 n..d of content 136%, liquid 210 -of -,,, " o....d...

limit 80%, plastic limit -- _ p -...

28%, ignition loss 9.2%0,1

Solidificant: Ordinary portland cement at 100 kg/mi3

Target solidified strength: --.....

Unconfined compressive -

strength 0.5 kg/cm2

(28-day curing) 8.t eie ind.ie. •sofdified sediment Strp

Solidified sediment volume: Length of strip: 2728m.

Approx. 11,000 mi Figure 20. Arrangement of solidified Period of work: December strips and material

1979 - January 1980 strengths of sheets and

nets laid

Kasumigaura (Test Works)

This is an exampleof Case B. Bottom sediments were dredged at a high solid content with a negative-pressure suction and pneumatic-pumping d~redger

' I PS 75 kg m/sec.

208
barge (dredging capacity 100 m3/hr) with the pipeline branched part way to

provide solidification of the Sediment. Mixers of the pipeline-mixer type

were used for solidifying. A solidificant slurry was injected into the

sediment in the branched pipe, the sediment was passed through the mixer,

and the sediment intermixed with solidificant was discharged at the disposal

area.

Properties of sediment: Water content (at time of solidification )

29%, liquid limit 127%, plastic limit 48%, ignition loss

12.4%

Solidificant: Ordinary portland cement at 116 kg/M 3

Solidified strength: Unconfined compressive strength 0.4 kg/cm2

(28-day curing), unconfined compressive strength 3.0 kg/cm2

(180-day curing)

Solidified sediment volume: 40 m3

Period of work: 1980

Tagonoura Harbor

This is also an example of Case B. Bottom sediment brought up by grab

dredger (bucket 6 m3 ) was transferred to a soil transport barge (capacity

300 - 500 M3 ) and hauled to a wharf. Mixing was performed upon adding solidificant slurry from the solidificant-supply plant using a clamshell at the

wharf. The mixing time was approximately 2 hours per transport barge.

Bottom sediment given solidification on the barge was left untouched

for 24 hours and then placed on land by clamshell, left another 24 hours at a

stockpile, loaded on dump trucks, and hauled to a containment area at

the Fuji River channel approximately 5 km distant.

Example sediment properties: Water content (at time of solidification)

180%, liquid limit 120%, plastic limit 55%, ignition loss 27%

Solidificant: A special cement-type solidificant of 144 kg/M 3

Target solidified strength: Unconfined compressive strength 0.3 kg/cm2

(2-day curing)

Solidified sediment volume: 120,000 M3 (part c 4th-phase works)

Period of work: February - May 1979 (part of 4th-phase works)

Hama River

This is an example of Case C. The Hama is a river in the city of

Nobeoka in Miyazaki Prefecture.

The river with a width of approximately 40 m was cofferdammed in half

by double steel sheet-piling in the direction of flow. The interior of the

cofferdammed area was dewatered by pump, and bottom sediments were solidified

in situ by a ship-type treatment machine. The solidified sediment was dug

up by backhoe after approximately one month of curing, and hauled by dump

truck to a containment area. At this time, a part of the solidified sediment

was left in place to secure the level of the improved river channel cross

section. An overlay of concrete was provided on the bottom after excava209
tion and the bed was restored as a water channel. The other half of the

cofferdamled river was filled with soil after the solidification of the sediment to build up land which was utilized for a park.

Properties of sediment: Water content 174%, liquid limit 82%, plastic

limit 36%, ignition loss 11%

Solidificant: Ordinary portland cement at 100 kg/m 3

Target solidified strength: Unconfined compressive strengtý( 0.6 kg/cm2

(28-day curing)

Solidified sediment volume: 35,000 m3

Period of work: 1974-1976

CONCLUSIONS

Four examples of solidified sediment are discussed. From these experiences, it was found that the aims of solidification such as (1) increasing soil

strength and (2) preventing the leaching of toxic substances, could be attained

on a practical scale. However, further research on the solidified sediment,

with respect to solidification practices, is still needed.

210

- o A• 
AD POO2 4 04

JAMES RIVER, VIRGINIA

DREDGING DEMONSTRATION IN CONTAMINATED MATERIAL

(KEPONE)

DUSTPAN VERSUS CUTTERHEAD

R. G. Vann

Dredging Management Branch

Norfolk District, Corps of Engineers

803 Front Street

Norfolk, Virginia 23510

ABSTRACT

-ý The James River, Virginia, is a tributary

of the Chesapeake Bay polluted with the toxic

pesticide Kepone. The Norfolk District,

Corps of Engineers, will conduct a dredging

demonstration project as part of the

maintenance of the James River Channel. The

goals of the demonstration are to achieve

containment of a layer of polluted sediment;

to minimize resuspension of pollution at the

dredge head; and to remove the sediment at

in situ density. In order to achieve these

goals, a dustpan suction head will be

specially adapted and fitted on a typical

hydraulic pipeline dredge. Tae dredge w-4ll

be operated in the dustpan mode using a

dredging method designed to obtain precise

positioning of the suction head within the

specified layer of polluted sediment. The

dredge will also be operated as a

conventional cutter suction dredge for

comparison with the dustpan arrangement.

Monitoring of operating parameters on board

the dredge, and of water quality parameters

around the perimeter of the operation, will

be accomplished with appropriate

instrumentation to document the effectiveness

of the two dredging methods. It is anticipated that the dredging demonstration will

result in a method of adapting readily

available cutterhead dredge plant for the

cleanup of polluted sediments.

211
INTRODUCTION

The waterways within the Norfolk District of the Corps of

Engineers are generally free of hazardous substances. Where

dredging is required to maintain navigable channels, pollution

normally does not impede this activity. The James River, however,

where the toxic pesticide Kepone has polluted the waterway, the

dredging of the channel has became a major issue. The Kepone

pollution h4s also directly resulted in the Norfolk District's

dredging de ons ration for Kepone removal.

BACKGROUND

The James River is a tributary of the Chesapeake Bay and is located in thel State of Virginia abc:ut 400 miles (640 kilometers) south

of New York (Figure 1). Its sources are in the Allegheny Mountains

of West Virginia and Virginia. Between the City of Richmond and the

mouth at Hampton Roads, a distance of 90 miles (145 kilometers), the

James is tidal and navigable. In this portion of the river, a

navigation channel 25 feet (7.6 meters) deep is maintained tn serve

the ports ofI Richmond, Hopewell, and the industries between these

cities. These industries and port activities depend on the Jameb

River Channel for the economical transport of many commodities and

raw materials. As is the case on many of the world's waterways,

local industIries have created pollution. In particular, the Allied

SWASHING ON 0 Ck

.•-? ,,- ii -

It

Figure 1. Location of the James River, Virginia

212
7.-

Chemical Corporation, at plants in the vicinity of Hopewell,

Virginia, was .'esponsible for the release of Kepone into the James

River system. Between 1967 and 1975 it is estimated that as much as

65,000 pounds of the highly toxic chemical were discharged into the

James River basin.

The extent of the Kepone pollution was not fully discovered

until 1975, and the production and resultant discharge of the

chemical was ceased that year. The closing of the James River to

fishing and shellfishing was ordered by the Governor of Virginia in

December 1975. Since that time the State has periodically sampled

the river and its seafood in order to monitor Kepone levels, and

promulgated regulations pertaining to seafood harvesting in the

James River. In recent years, Kepone levels have decreased in organisms to the extent that, for most species, commercial harvesting

is again permitted within certain geographic and seasonal limits.

However, Kepone data obtained during the sumer and fall of 1981 by

"the State show that this trend ha* reversed, perhaps only

tempor3rily, and that Kepone levels in certain fish have risen.

While the now relaxed fishing regulations have not been made more

restrictive, it is apparent that the Kepone problem will persist for

years. Following discovery of the extent of Kepone pollution, and

formation of State and Federal task forces, the U.S. Environmental

Protection Agency (EPA) conducted the Kepone Mitigation Feasibility

Study. As part of this effort, the Norfolk District was request-d

to evaluate alternatives for the removal of Kepone-contaminatEd

sediments, and to investigate all potential dredging technology and

methods to control resuspension and secondary pollution. During

this mitigation study, a delegation from EPA and the Norfolk

District visited Japan to observe specialized methods of handling

toxic sediments. The group was favorably impressed witi. the Oozer

Dredge because of its alleged ability to achieve a high solids to

water ratio and minimlze resuspension. As a result of the Japan

visit, the Norfolk District recommended that a demonstration project

ue conducted on the James River to evaluate the Oozer Dredge in

comparison with & conventional cutter suction dredge. The basis for

the recommendation was that there would be a need to know the best

method of removing pollutant "hot spots", whether consisting of

Kepone in the James River or toxics in other areas of the country

if the Corps were assigned a cleanup mission.

The recommendation to conduct a demonstration project was made

to higher authority in early 1979, and resulted in much discussion,

among dredging experts both within and outside the Corps.

Informally, it was suggested that a dustpan dredge, appropriately

modified, could perform as well as the Dozer Dredge in removing

213
polluted sediments. The dustpan type dredge uses hydraulic

transport, as do cutter suction dredges, and is extensively employed

by the Corps for navigation dredging of granular materials on the

Lower Mississippi River. Furthermore, it was suggested that parts

from retired Corps dustpan dredges, available In the St. Louis

District, could be adapted to available cutterhead dredge plant. As

a result of these discussions, Amalgamated Dredge Design,

Incorporated, presented a formal proposal to modify an available

dustpan suction head and adapt the dustpan to a contractor's cutter

suction dredge. The effectiveness of this arrangement for dredging

polluted sediment would then be tested and compared to the

conventional cutterhead arrangement. The dredging woild be

accomplished as part of the maintenance of the James River Channel.

This proposal was the basis for the dredging demonstration project

in the James River.

PROBLEM DESCRIPTION

The problem is not just to dredge the contaminated sediments--

it is to attempt total containment at the dredge head of a specified.

layer of material as near in-place density as possible. This vill

involve minimizing reauspension of material at the head, minimizing

the volume of the specified material left behind, and minimizing the

mount of water added during the dredging process.

To achieve total containment, the problems discussed in the following

paragraphs must be solved.

Entry Design

The entry design of the dustpan head must ensure that there is

no escape of polluted material. The entry design must also be based

on the characteristics of the ch4nnel sediments to be dredged, which

are shown on Table 1.

214
TABLE 1. SEDIMNrT PROPEkTIES

Pro 2 ____L_ Value

Classification (USCS)* Silty-clay (CH)

Moist Unit Weight (Avg.) 84 pounds per cubic foot

(1300 grams

per liter)

Moisture Content (Avg.) 144 percent

Liquid Limit 100 percent or

greater

Plastic Index 60 percent or

greater

Kapone Content (Avg.) 0.1 parts per

million

* Unified Soil Classification System.

The material to be dredged from the James River Channel exists

in a fluid state. Therefore, it is not necessary to have any means

to agitate or fluidize the material; in fact, this would be

undesirable since the goal is to minimize dilution and resuspension

of the material.

An existing dustpan suction head from the retired Corps Dredge

KENNEDY will be used for the demonstration project. Since dustpan

dredges normelly operate in granular materials, the head was

equipped with digging teeth and water jets at the mouthpiece to

enhance the ilow of material. This mouthpiece section was removed

from the head and will be replaced with a newly fabricated section

without water jets or teeth.

The KENNEDY dustpan head ir 28 feet (8.5 meters) wide and

8 inches (20 centimeters) deep. In order to overcome the entry

losses of the flat, rectangular mouthpiece, and to accelerate the

material through the dustpan, it will be necessary to build up a

layer of material above the top edge of the entrance. A rollover

plate, shaped like a bulldozer blade, will be installed on the top

of the dustpan to artifically create the needed head of material

(Figure 2).

215
NDustpan head

SN 'NRollover plote

"-' - - Material seal

River Bottomn

PROFILE

Figure 2. Dustpan head with rollover plate

The layer of material created above the entrance may have a

tendency to spill over the sides, leaving some of the specified

material undredged. To prevent this condition, wing plates will be

attached to either side of the dustpan head and a splitter plate

will be attached in the center, as shown in Figure 3.

These wing plates and splitter plate will keep the layer of

material above the entrance and provide some stability for the head

as it advances into the cut. The wing plates will also prevent the

ingress of dilution water at the sides.

216
SUCTION PLATE

PIPING WING

)PLATE

WING MHEAD ENTRANCE PLATE

Figure 3. ModiVfed dustpan head

Dredge Positioning

Positioning of the dredge will be another problem which must be

solved in order to a-.nieve total containment of the polluted

material.

Dustpan dredges normally operate by anchoring two crossed

headwires upstream of the dredge, and advancing on these wires into

the cut. Th.!! ;trong river currents of the Mississippi or Missouri

Rivers and the crossed headwires keep the dredge in position within

limits acceptable for channel maintenance dredging.

On the James River, this system would not work well. The river

currents vary in strength and direction with the tidal cycle as

compared to the strong, steady current in one direction on the

Mississippi. Greater positioning accuracy, estimated to be

+ I foot (0.3 meter), must be achieved for the goal of total

containment. The lack of a strong, steady current on the James,

coupled with the need for greater accuracy, requires that other

methods of dredge positioning be investigated.

217
Electronic positioning systems were explored as a means of

positioning the dredge. It was determined that there is no

commercially available system which can guarante. the desired degree

of accuracy. The most accurate system available, ohich utilizes

measurements from three separate shore stations and a computerized

least squares adjustment of these measurements (Figure 4), can

guarantee precision of + 3 feet (1 meter).

. ,*..-

T T =A" "M. STATI...ON.

STATION

Figure 4. Electronic positioning system

This system will be used in the demonstration project to

delineate the specified areas to be dredged. The problem of

positioning the dredge with the required degree of accuracy,

however, cannot be solved with electronic equipment, but must

instead be solved by the choice of an appropriate dredging metb._'d.

218
DREDGING METHOD

The method of dredging by dustpan chosen for the project is

unorthodox, but will enable accurate and positive positioning of the

dredge. Rather than working along the length of the navigation

channel, the dredge will be working across the channel and

perpendicular to the tidal currents.

Five wires will be used to position and maneuver the dredge in

the dustpan mode ('igure 5).

0 -

S

COSTN -,O101 CR MOOLf )

00

4E 4

Figure 5. Dredging wire diagram

Radial wires A and B with a comon anchor point will maintain

the dredge on a slightly curved path across the channel. Wire C

will maintain a coustant tension in wires A and B with the use of an

in-line tensiometer having a remote display in the dredge lever

room. Digging wire D will pull the dredge into the cut, and return

wire E will bring the dredge back to the beginning of the cut.

219
The step from one cut to the next is 28 feet, the width of

the dustpan head. This step will be accomplished by paying out an

equivalent amount of wire on the calibrated radial wires and

adjusting the constant tension wire. The desired accuracy of

+ I foot (0.3 meters) for dredge positioning will be obtained by

accurate calibration and measurement of the amount payed out on the

radial wires.

CUTTER SUCTION DREDGE

During May 1981, the Norfolk District advertised for bids for

lease of a cutter suction dredge to be used in the James River

demonstration project. A contract was subsequently awarded to

Norfolk Dredging Company, the low bidder, for lease of the 18-inch

cutter suction dredge ESSEX. It was at this time that Amalgamated

Dredge Design, under a separate contract with the Norfolk District,

began detailed engineering and design work for the project based on

the characteristics of the ESSEX. The principal characteristics

are shown in TABLE 2.

TABLE 2. CUTTER SUCTION DREDGE ESSEX

PRINCIPAL CHARACTERISTICS

Characteristics Value

Hull - Length 140 feet (42.7 meters)

Breadth 36 feet (10.0 meters)

Depth 10 feet ( 3.0 meters)

Cutting Power 300 horsepower (225 kw)

Dredging Depth 40 feet (12.2 ,eters)

Pump - Suction 21 inches (53 cm)

Discharge 18 inches (46 cm)

Power 2250 horsepower (1680 kw)

Ladder and Swing 75 horsepower (56 kv)

Winch Power - 400 rpm

Upon close inspection it was determined that the dredge ESSEX is

well equipped to accommodate the installation of the dustpan from

the dredge KENNEDY, with a minimum of modifications. The winches on board can also be easily modified to enable the dredge to onerate in

the dustpan mode as proposed.

220
MONITORING OF DREDGING OPERATIONS

In order to compare the operdtion of the dredge ESSEX while

tests are carried out in the dustpan mode with the operation of the

dredge in the conventional cutterhead mode, several parameters will

be closely monitored.

On Board Instrumentation

Dredge output will be continuously monitored through the use of

a package of automatic instrumentation. The package consists of

vacuum indicator, pressure indicator, density meter, velocity meter,

production calculator, and yield indicator. A ladder depth

indicator will enable accurate control of the dredging depth.

Continuous tidal information will be provided by a radio tide

transmitter, in order that the dredging depth may be accurately

adjusted for the height of tide.

The efficiency of removal at the dredge head will be monitored

in order to determine if the goal of total containment is being

achieved. This will be accomplished by taking water samples with a

series of tubes mounted around the head and measuring the turbidity

of the samples with a transmissometer mounted on a sampling tank.

Off-Dredge Monitorins.

Around the perimeter of the dredge and disposal sites, the

Norfolk District will monitor water quality. Parameters to be

measured include turbidity, suspended solids, dissolved Kepone,

total water column Kepone, and current speed and direction. The

monitoring program is designed to detect significant changes in

Kepone levels resulting from the dredge operation. The Virginia

State Water Control Board will also be monitoring the

bioaccummulation of Kepone in local species of marine organisms.

The effectiveness of a submerged discharge diffuser developed by the

Waterways Experiment Station will be tested at the disposal site as

well.

POTENTIAL PROBLEM AREAS

The testing of the modified dustpan arrangement for dredging

contaminated sediments may potentially present operational problems.

Crew training will be essential in overcoming these problems.

The dredge crew of the cutter suction dredge ESSEX is not familiar

221
with the dustpan method of dredging, much less the unorthodox

adaptation of this method for dredging in the James River Channel.

Comprehensive crew training sessions are being planned mad will be

conducted prior to start-up of dustpan operations in order for the

crew to become familiar with the dredging method.

Prior to start-up of dredge operations, but following the

successful alteration of the ESSEX and installation of the dustpan

head and test equipment, a series of tests will be run. These tests

will ensure that each of the systems on board the dredge is

functioning properly, and that the dredge as outfitted is capable of

conducting the dredging tests. An adequate supply of spare parts

will be kept on hand so that downtime of the instrumentation

package will be kept to a minimum.

Much time will be required during the demonstration project for

moving the dredge to start each new cut since the cuts will be no more than 350 feet (107 meters) in length. There will also be

considerable time spent resetting the various anchors .for each new series of cuts. While production is not a primary goal of the

demonstration project, excessive nonpumping time would nonetheless

be undesirable. Accordingly, procedures will be developed, and the

crew properly trained, so that the maneuvering and resetting time of

the dredge between cuts will be minimized.

One minor problem is the possibility of the choking or blocking of the dustpan head. It is anticipated that this condition will

seldom occur; however, procedures will be developed to unblock the

head should it become choked or blocked with debris.

CONCLUSIONS

Design drawings and specifications for the modifications to the

ESSEX are in the process of finalization, and detailed plans for

crew training and accomplishment of the dredging tests are in

preparation. The dustpan head and dredging ladder from the dredge

KENNEDY have been removed and delivered to the contractor's yard.

The demonstration project as a whole is about to make the transition

from design phase to the construction and operation phases.

A great deal of effort has gone into the project up to this stage

by the Norfolk District, our contractors, and the many technical

advisors within the Corps. Environmental coordination of the

project with the various regulatory agencies has also been a

monumental task. While it is believed, at this stage, that the

technical phase of design and environmental coordination is behind

us, the construction and operation phases may pose additional

222

/A
hurdles to overcom. The Norfolk District is optimistic, however,

that the successful completion of the project will result in

resumption of full maintenanice of the James River and a proven

method of adapting readily available dredge plant for cleanup of

polluted sediments.

2/

I

223
10 "rho.

BIBLIOGRAPHY

A Proposed Method for Removal of Contaminated Soils from Marine Estuaries

and Waterways by Adoption of Conventional Dredging Methods, Amalgamated

Dredge Design, Inc., June 1979.

"Demonstration of Advanced Dredging Technology, Dredging Contaminated

Material (Kepone) , James River, Virginia, Douglas L. Haller, Norfolk

District, Corps of Engineers, 1981.

Dredge Demonstration Project James River, Virginia, Design Concept for

Proposed Dredging Method, kmalgamated Dredge Design, Inc., prepared under

contract with Norfolk District, Corps of Engineers, July 1981.

Evaluation of the Submerged Discharge of Dredge Material Slurry During

Pipeline Dredge Operations, Robert W. Neal, George Henry, Stephen H. Green,

JBF Scientific Corporation, prepared as part of the U. S. Waterways Experiment Station Dredged Material Research Program, Technical Report D-78-44,

August 1978.

James River Demonstration Project Feasibility Study, Amalgamated Dredge

Design, Inc., prepared under contract with Norfolk District, Corps of

Engineers, January 1980.

James River Maintenance Dredging Demonstration Prolect, Goose Hill an'l

Dancing Point - Swann Point Project Channels, Virýinia, Subsurface

Investigation, David A. Pezza and Ronald L. Buck, Geotechnical Engiuieering

Section, Norfolk District, Corps of Engineers, January 1981.

Mitigation Feasibility for the Kepone Contaminated Hopewell James River

Basin Areas, Appendix B, U. S. Environmental Protection Agency, Office of

Water and Hazardous Materials, Criteria and Standards Division, Washington,

D. C., June 1978.

Review of the Proposed Dredging Procedures Selected for the Dustpan Mode

for the Dredge Demonstration Project, James River, Virginia, the Sand Hen

Corporation, prepared under contract with Norfolk District, Corps of

Engineers, September 1981.

Specification for the Conversion and Modification of the Dredge Denonstration Project, James River, Virginia, Amalgamated Dredge resign, Inc.,

prepared under contract with Norfolk District, Corps of Engineers,

September 1981.

224

S/ I I I I

i i i i I'I I I I I I I I I I
AD P002 4 0 5

TEST DREDGING OF BOTTOM SEDIMENTS IN OSAKA BAY

Hiromi Koba

Toyoaki Shiba

Japan Dredging and Reclamation Engineering Association

2-8, Tor3nomon I chome, Minatoku, Tokyo, Japan

ABSTRACT

Test dredging was carried out with cutterless

dredges in Osaka Bay where bottom sediments contain

severe organic contamination. The Oozer pump dredge

was also studied in thi. test work. The following

results were obtained:

a. The sludges may be efficiently dredged with

the suction mouth of the dredge swinging

back and forth along the seabed;

b. By setting the swing speed for dredging

from 6 to 7 m/min. or less, little contamination in the vicinity of the suction

mouth occurs.

c. The efficiency of the dredge is approximately

250 m 3/hr on the average, with a concentration

of 30 to 40 percent by volume.

d. The sludge dredged may be efficiently disposed

of by transporting it on a barge to the disposal site .

e. The advantage of the Oozer pump dredge lies

in that little excess water is sucked in

while dredging which facilitates disposal

of the slurry.

INTRODUCTION

The Inland Sea is rich in marine resources and has long supplied the

Japanese with quality proteins. Along with a rapid increase in the population

225
on the coast in recent years, however, a eutrophication phenomenon of the

seawater has occurred in this sea area and the fish and other marine products

have died due to the so-called "red tide." If this problem is left unsolved,

a critical problem could occur in Japan's protein sources. To cope with the

problem, the Japanese Government has executed legal restrictions on the quality of the wastewater that may be discharged into the Inland Sea, but the

occurrence of the red tide has not been so easily eliminated. It is believed

that the red tide is caused by the load from organic sludges that has built

up over a long period in the bottom sediments of the Inland Sea. Accordingly,

it would doubtlessly be one of the most effective methods to dredge and remove the accumulated sludge in order to completely eliminate the damage caused

by the red tide. However, since the quantities of organic sludges are enormous, the expense of the dredging work to remove such sludges would be equally

huge. It is, therefore, significant to determine the most rational method of

dredging. Osaka Bay is situated at the far east end portion of the Inland

Sea, where a vast organic contamination load from Osaka, one of the largest

cities in Japan has accumulated and the occurrence of the red tide is greatest.

Hence, Osaka Bay was chosen for the case study. The authors of this article

participated in the sediment removing test work executed by the Japanese

Government; their observations of the test work are reported herein.

SUMMARY OF TEST WORK

Site of Execution

Organic sludge extends over a vast region of the Inland Sea, and the

contamination, near large cities such as Osaka and Hiroshima is of a particularly high level.

Figure I shows chemical oxygen demand (COD) and sulfides contained in

the surface layer sediment of Osaka Bay and the proportion of ignition loss.

Regions with a high concentration extend along the coast and the bayhead for

three items, and a region about 2 km away from the Nishinomiya Breakwater of

Osaka Bay was selected as the site of execution (Figure 2).

Test Condition

The principal test conditions are shown in Table 1. In this table, water

"content renreseuts a weight percentage obtained by dividing the weight of the

water contained in the sediment by the weight of dry soil.

Execution Method

The dredging study was carried out as indicated in Figure 3. The principal ships and equipments used for the study are given in Tables 2 and 3.

(1) Dredging Work

The sludge was dredged and then loaded into a pusher type box barge via

a sludge discharge pipe.

226
N

01eKobe Kobeda o~ a

//

(A) COD(" 9/hg) (B) Sulfid.( m gkg) (C) Ignition loss (4)'

Figure 1. Substance distribution of the sediment surface layer of

Osaka Bay (summer)

(Note): From "Osaka Bay Sediment Purification Study," 1976 and 1978, The

3rd. District Port & Harbour Construction Fureau, Ministry of Transportation

(2) Transportation Work

The dredged sludge and water were transported to the unloading base site

of the disposal area about 5 km from the dredging site by the pusher type box

barge.

(3) Dredge Unloading Work

At the unloading site, the dredged sludge and water were discharged to

the dispo,'al site using a barge unloader ship.

The processing plant at the disposal site had a maximum processing

capacity of 2,000 m3 per day and processed the disposal area effluent by the

simple aeration process system and the flocculation-sedimentation process.

The effluent water quality was up to 20 mg/i for biochemical oxygen demand

(BOD) and 70 mg/i for suspended solids (SS).

Test Results

In this dredging test, the following five items were examined:

a. Dredging operation method

b. Dredging efficiency

227
Kobt N

c, x 1w

study site kal

Wiura.koatyama Frstd

2281 k
TABLE 1. CONDITION OF EXECUTION

Study No. 1 No. 2

It em March 1980 August 1960

8000 m2 4800 m2

Dredging area

1(1OO m x 80 m) (120 m x 40 m)

Water depth -16 m

Specific gravity 2.57

-Water content about 150,%

Soil 250 %

(typical example) .Grain-size distribution

cobble 0 % sand 1%

silt 50 % clay 49 o

100m

No. 1

40 ,t :.5 m

No. 2

,' X .

Work zone 40 . / t = 1.0 m ,

t = t t

40 0.4 rr 0.8 1.2m

40 m 40 m 40 m

229
/ (Dredging)

S (Sludge unloading)

(Sludge dumping)

(Transpor tat Ion)

Figure 3. Execution flow sheet

c. Efficiency of transportation and sludge unloading works

d. Accuracy of dredging work

e. Contamination during-dredging work

The results are discussed below.

Dredging Operation Method

Contamination during the dredging work was primarily caused by movement

of the suction mouth. Hence, the swing speed must be adjusted in order to

cope with this problem.

This test was carried out in the No. I study under the conditions shown

in Table 4. In this table, dredging soil thickness represents the thickness

of the soil that must be removed. "Dredging times" is the number of times

the suction mouth was moved planewise per one time advance.

Table 5 represents the test results concerning the evaluation of the

dredging operation method. In this table, under removal efficiency, dredge

quantity represents the soil capacity removed at the seabed, and conicentration

represents a volume percentage obtained by dividing the sludge quantity by

the slurry quantity.

Efficiency of Dredging Work

As shown in Table 5, the swi:ig speed may be set to 6 m/min. to efficiently

dredge the organic sludge of Osaka Bay. Accordingly, the efficiency of the

dredging work is studied in the subsequent study by setting the swing speed

to 6 m/min. and changing the soil thickness to be applied to the suction mouth

(Table 6). (The swing speed was set decreasing to 5 m/min. in Zone C in the

No. 2 study (effected in August) since the soil thickness excavating each time

was as great as 0.6 m compared with that in the other cases.)

230
TABLE 2. PRINCIPAL SHIPS ANDI EQUIPMENTS

(CARRIED OUT IN MARCH)

Work Item Specification Quantity

Dredge Oozer npo systemn 1 1000 m l/hr typel

SWindlass 0 240 ps* bS-ton suspension 1

SLoader 2500 tons 1

• Discharge 560 mm in dia. biy 6 m in 375 m

a) pipe length/pipe _

STraffic 50 Ps 1

Patrol 50 ps 1

3000 m3

Box barge

o 1200 m 1

M 0 Z - 3000 ps 1

" C Pusher

S- • 2000 ps 1

Unloader 610 ps 1

Windlass 240 ps 15-ton suspension 1

Transportation 300 m 1

S Crawler bed 150 tons 35-tcn suspension 1

STug 30 0 ps 1

SSubmersible 50 ps 3

o sand pump 10O0 loops. ps 1

Generator 115 KVA 1

200 KVA 2

Pumping Centrifugal purip

equipment ý300 x 180 ps 1 1

Discharge pipe $i40 x u.0 m//pipe 300 m

ps mneans metric horse-power; and 1 p3 = 75 kg m/sec.

231
TABLE 3. PRINCIPAL SHIPS AND EQUIPMENTS

(CARRIED OUT IN AUGUST)

Work Name Specification Quantity

Dredge Clean up system 1

o Windlass 240 ps 15-ton suspension 1

Z Traffic 280 ps 1

Patrol 35 ps 1

a,

Traffic 12 ps 1

SBox barge 00 M3 3

I. 500 m.3

Pq ....

c 4 'd 1000 ps 1

S0 o Tug S600 ps 3

Unloader 610 ps 1

Windlass 240 ps 15-ton suspension 1

0 Traffic 280 ps 1

Pumping • T eiCentrifugal equipment pump ý300 x 180 ps 1

0

! Generator 200 KVA 1

Discharge ý410 x 6.0 m/pipe 300 m

pipe

On the basis of Table 6, the dredging efficiency results were approximately the same in both the No. 1 study and the No. 2 study, as illustrated

in Table 7.

The sludge quantity in Table 7 is the value obtained by dividing the

dredged soil quantity by the sum of the dredging time and the advancing time

required for advancing work.

232
I

TABLE 4. OPERATING CONDITION OF DREDGE

(NO. 1 STUDY ONLY)

Dredge zone Test case Swing speed Dredging soil Dredging

(m/min) thickness (m) times

A-1 4

A A-2 6 0.5 1

A-3 8

B -1 4

B B -2 6 1.0 2

B-3 8

TABLE 5. EVALUATION OF OPERATION METHOD

Swing speed

Item m min.) 4 6

Sampling, SS analysis 0 0 0

Contami- Underwater television observation 0 Q

nation _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ I__ 

Sonar recording 0 0'\1

Removal Dredge quantity, Concentration Efficienc- x () 0

Overall evaluation 0

C: good, /•: fair, X: bad

233
TABLE 6. OPERATING CONDITION OF DREDGE

(EFFICIENCY STUDY)

Study Dredging Dredging soil Swing speed Dredging

zone thickness (m) (m/min.) times

A 0.5 1

No. 1 6

B 1.0 2

A 0.4 1

6

No. 2 B 0.8 2

C 1.2 5 2

TABLE 7. EFFICIENCY' OF DREDGING WORK

- Dredging sludge Dredging slurry Concentration

Study zre quantity quantity 3 M

zone per hour (mm/hr) per hour (m3 /hr)

A 177 576 31

N0. 1

B 237 709 33

A 251 534 47

o. 2, B 227 731 31

C 335 984 34

234
Efficiency of Transportation and Sludge Unloading/Works

The cruising speed, operation time, and fuel consumption of the pusher

barges and the operation time and fuel consumption of the sludge unloading

ship were examined and general results were obtained.

Accuracy of Dredging Work

When compared with the work by conventional cutterhead dredges, the

sludge dredging work calls for a higher level of accuracy because:

(1) The sludge to be removed cannot be left unexcavated.

(2) If the uncontaminated layer is also dredged and removed, the

dredging quantity as a whole increases, causing problems with the

capacity of the reclaimed land and the secondary treatment (such as

solidification).

The soil thickness and the advancing distance of the suction mouth

(length of advance once the spud is changed for repiling) were within the

range of 10 to 20 cm, and the accuracy was within about 10% of a target set

value.

Contamination During Dredging Work

To examine the quantity of contamination occurring from around the suction mouth and its diffusing range during the dredging work, observation boats

measured the direction and velocity of the tidal currents flowing, measured

the contamination in the vicinity of the dredge, and analyzed the SS of collected water samples. Almost all the measured SS values were within the

range of 5 to 10 mg/2, which is within the mean SS background value of 9 to

10 mg/f in this sea zone (Figures 4 and 5).

The dredging operation in this study was effected at a swing speed that

does not cause contamination on the basis of Table 5; it was confirmed that,

throughout a series of examinations, no contamination problem occurred at all.

OOZER PUMP DREDGE STUDY

The Oozer pump dredge was used in the No. I study of this dredging test

work.

Photo 1 and Figure 6 illustrate an overall view of the Oozer pump dredge.

Dredging Equipment

For this test work, we designed the dredging mechanism as shown in

Figure 7; the outline is as follows:

235
*bth da, of March Condition after second hour from beginning of

dredging.

Flow o.1 m/sec.

low-- upper layer (3 m) "' / " Direction, mdl " ae 8m

Suction Velocity •dder layer (12 m)ý

mouth .6Measurmen- -udrlye 1 n

SSL

10

O-: - . - - - ----

sO st2 st3 sf4 st5 st.7 st9 st6 stB stlO Background

data

Figure 4. Muddiness in A Zone

8th day of March Condition after second hour from beginning of dredging

77•0 Flow 0.1 m/sec

Direction, upper layer (3 m)

Suction-" Velocity middle layer (8 m)

mouth Measurment- under layer (12 m)

40-

ss _____

10 -

0 • . •Ba -

st1. st.2 st.3 stA sA5 st7 sts St6 st8 silO ground

data

Figure 5. Muddiness in B Zone

"236
Photo 1. View of dredge

I.:I

r/
a. e• Oozer pump was used for dredging because it delivers the sludge

bt means of pneumatic piston operation as shown in Figure 8; with

t is operation an excessive amount of water is not sucked in when

siopping the pump before and after dredging work and during replacemint of spuds.

b. I is thought that dredging can be carried out without agitating the

s..udge if a cutterless suction mouth is used.

c. A speed changeable winch is used that can freely adjust the swing / - speed within the range of 0 to 12 m/min, so that the dredging can be

mtched to the properties of the sludge.

d. Cjintamination during dredging can be constantly supervised by an

uzderwater television fitted to the upper part of the suction mouth.

e. The purpose of sludge dredging is to remove the contaminated layer,

not to dredge the seabed to a constant depth (Figure 9). To- enable

the dredge to move along the ups and downs of the seabed, three sonars are fitted to the upper side of the suction mouth. The seabed

that has not been dredged and that has been dredged are continuously

recorded while dredging and the suction mouth can be constantly

moved up and down so that the sucked-in sediment thickness will match

the planied value.

DETAILI OF PORTION "A'

(AT FROM TV FRONT SURFACE)

UNCERWATER TV

SUNDERWATER TV-.

SI RTONAR (REAR LEFT)

SONAR(REAR RIGHT

SONAR (REAR,2 SETS)

GDRAINAGE PUMP , ,• •(LEFT) .

PUMP(RIGHT)

SUCTION !Mf•TH • •

Figure 7. Dredging mechanism (lengths are

measured in millimeters)

238

A~* -

4i
COMPRESSED AIR

VACUUM PUMP DISCHARGE VALVE

UPPER LIMIT DETECTOR 4 j, ý

LOWER LIMIT

DETECTOR

VACUUM---/14r #T

HYDRAULIC PRESSURE

BALL VAL.-VE..'.

SUCTION MOUTH

Figure 8. Oozer pump operation

CONVENTIONAL DREDGING SLUDGE DREDGING

-WATER DEPTH IS WATER DEPTH IS CONSTANT NOT CONSTANT

SURFACE OF THE SEABED SURFACE OF THE SEABED

BEFORE DREDGING BEFORE DREDGING

DREDGiNG SLUDGE DREDGING SLUDGE

ITHICKNESS THICKNESS

SURFACE OF THE SEABED SURFACE OF THE SEABED

AFTER DREDGING AFTER DREDGING

Figure 9. Explanation of dredging sediment thickness

239
Effective Operation Method

Operation Method of the Dredge

The operation method of the dredge selected was the same as that of the

conventional cutter pump. In this method, the dredging.work is carried out

while the spuds are piled to fix the hull and the suction mouth is moved to

left and right by the swing winch. The operator is accustomed to this operation and the organic sludge is such that it is equally piled up along tie

surface of the seabed. In view of these reasons, the cutter pump method is

considered to be a rational dredging method.

Figure 10 illustrates the method of operation; the outline is as follows:

a. The order of operation is different to some extent between the first

excavation and the second. First, we will explain the order of the

first excavation. The sludge is dredged at -- @ ; when it

reaches 7, the suction mouth is raised and the pump is stopped and

returned to @ - . The temporary spud is piled at , and the

working spud is removed. It is advanced to @ 0 in this state

and, at (9 , the working spud is piled and the temporary spud is

removed and swung to @ - @ . At 0 , the suction mouth is lowered

into the sludge again and the pump is operated and the sludge is

dredged in the order of -* @ . In the second excavation, the

sludge is dredged at Q - ( , the suction mouth is lowered at v.,

and the sludge is dredged ac @ -* @( again. Then the suction mouth

is raised at T to hold it away from the surface of the seabed and

the pump is stopped to return to D - @; at @(, temporary spud is

piled and the working spud is removed. Subsequent advancing operations are carried out as indicated for the first excavation.

b. In both the first and second excavations, the position of the suction

mouth is overlapped with the side of the trace of dredging so that

the siudge may not collapse and fall down into the trace and remain

there.

c. While the advancing operation is carried out, the ladder is wound up

and the suction mouth is held away from the surface of the seabed.

This action prevents the sludge from being stirred by the suction

mouth when the hull rocks due to the repiling action of spuds.

The operation method when applied to the area of the test work is shown

in Figure 11. @- ( in Figure 11 represent the order of the dredging

operation.

( and (73 represent the work zones of operation method study, (3) - (7)

represent the efficiency study zones, and - represents the direction of dredging and advance.

240
OVER LAP

SUCTION MOUTH WIDTH. UCT ION MOUTH WIDTH

/ ~ FFECTIVE SUCTION WIDTH

RIGHT END LINE ~ _____

DISTANCE MOVED FORWARD

WORKING SPUD

LEFT END LINE

(SWING SYSTEM PLANE)

OOZER PUMP DREDGE

THICKNESS DREDGED THICKNESS DREDGED

1ST TIME 2ND TIME

(SWING SYSTSM4 SECTION)

Figure 10. Dredging operation method

241
LINE OF SUCTION MOUTH MOVEMENT

3

Figure 11. Dredging advance in No. 1 test work

Efficiency and Accuracy of Dredging Work

According to our study, the work efficiency of the Oozer puinp dredge can

be expressed by the formula ina Equation 1 in accordance with the cutterless

suction mouth model shown in Figure 12.

c~o = q • . . . . . . .(1)

where qo: quan'ity of sludge dredged per operation time [m)/hr]

q: quantity of sludge dredged per dredging time (.,ihrj

q =60( - b) .v • t w

B: suction mouth width [m]

b: suction mouth overlap width fmJ

t: sucked sludge thickness [(,l

V : swing speed tm,/mini

w

242
TO OOZER PUMP

FORWARD

SUTINTRACE OFDRDGN

SWING DIRECTION• '. SWING"• DIETO 0 " TRACE OF DREDGING

Symbols

B: suction mouth width h: height of suction mouth

b: overlap width of suction t: sucked soil thickness

mouth

Vw: swing speed Vs: suction velocity

Figure 12. Cutterless suction mouth model

n: time efficiency of work

q n • W/V /(n . WlVw + W'/V' + Ts)

n: number of excavations

W: swing width fmj

V : swing speed during dredging fm/min.] w

W': moving distance of suction mouth during advance (m)

V ': swing speed during advance fm/minI W

T time rpquired for elevating spuds during spud

replacing operation [minl.

Here the operation time is the sum of the actual dredging time for excavating the sludge and the advance time in which the excavation is stopped

for advancing.

243
The term W' represents the moving distance of the suction mouth from 0 - @ 3 - Q in the second excavation shown in Figure 10, for example.

T is the sum of the time required for pulling out. and piling the spuds

at the points © and @ in Figure 10.

According to Equation 1, in order to increase the dredging efficiency,

the suction mouth width B , the sucked sediment thickness t , the swing

speed V w , and the operation time efficiency n must be increased while the

overlap width b of the suction mouth must be decreased. With respect to

Equation 1, however, there is a limit of application and if the values of

B • h , etc., are increased excessively, the suction flow velocity V in s

Figure 12 decreases and the sludge chokes up the suction mouth. According to

our experiences, we believe the suction velocity should be not less than

0.5 m/sec when the suction mouth sucks sludge up. The size of the suction

mouth B - h is determined so that said condition may be met and the sucked

sediment thickness t and the overlap width b are determined by Equation 1.

In addition to the above-mentioned factors associated with the work

efficiency, the sediment property, the size and shape of the work site, the

thickness of the sludge to be dredged, the kind of detrimental substances

contained in the sludge, etc., should be mentioned. These factors are

summarized in Table 8.

In this test study, the size of the suction mouth and the thickness of

sediment to be sucked were determined as follows:

suction mouth width B . . 3.4 m

suction mouth height h . . . 0.5 m

suction mouth overlap width b . . . 0.4 m

sucked sediment thickness t . . . 0.5 m

The dredging operation was carried out following Table 6.

The results of the test study are shown in Tables 9 and 10 and Figure 13.

The work time in Table 10 is the sum of the dredging operation time and

the rest time required for the contamination study and for moving the dredge

to another work zone by a tug, in which dredging is stopped. It is the total

restrictive time required for the dredging work.

Figure 13 shows the work result of the Oozer pump dredge. Plotting the

efficiency of the study of Osaka Bay in Table 9, it is found that both the

surface layer (water content 250%) and the lower layer (water content 150%)

are positioned in an area of better condition and higher efficiency was obtained in comparison with the sludge dredging work in general. This fact

has proved that our study is suitable.

244
TABLE 8. FACTORS AFFECTING DREDGING EFFICIENCY

edged sediment s t• y q^small 4 0 great

Item

(1) Water depth shallow deep

sand, cobble silt, clay

(2) Soil quality (hard) (soft)

(3) Condition of site becomes worse becomes better

in proportion to in inverse

a. sludge thickness the degree of proportion to

(small) ( ) the degree of

b. topography ( )

(complicated)

c. obstacles

(much)

d. navigating ships

(many)

(4) Prevention of contamina- severe mild

tion (swing speed) (slow) (rapid)

(5) Inspection of severe mild

excavated site

In comparison with the work efficiency of the cutterhead dredge, the

dredged sludge quantity q of the Oozer pump dredge is about 50% of that

of the cutterhead dredge, but the concentration is about 150 to 200% of the

latter, provided that the dredged sludge thickness is equal. The reason

q is small is because the swing speed V of 6 m/min is about 50% of the

swing speed of the conventional cutterheaA dredge. The concentration becomes

higher even though q is small because the Oozer pump is stopped during advance so as not to suck excessive water. Therefore, the Oozer pump dredge is

believed to be suited for dredging and removing the sludge.

To show the accuracy of the dredging, Figure 14 provides the sonar record

of the depth before and after dredging. The sonars were fitted to the upper

part of the suction mouth and the thickness t of the sucked sludge was confirmed while the work was carried out. As a result, the seabed of the excavated pit with a shape such as shown in Figure 15 was obtained. Using the

data in Table 9, the accuracy of the dredged sludge thickness is found to have

245
b p

4J U4 o co % -C N (Ni r ,

10 N 0 w 0-(-LC l 0

C (1) O%5O dCI c - l

gl., -- - -

0 co.

C- 0 Q) rd

- 044 H 0 I

0) Icl -4 - - \ \ -~ \

cn

ca,

-4 (1)~ 0 o 0 0 \0 0 0 0O N

bSobD-' '.0 mN U-. * m 

C.0)C.

$-P 0)04- 4-4

424
020

~0 0 r 00 C

0 0 . 0 0 - 0

400

.1 Cd0 0 0 0'0

4--

~0 0)

a) 0) -- ~- 0 0 (I - 0

0 .~0 - _ - 0--. 

-4 0

a, a) co

a) ~ 0 C 0 0 - '0 --

a. - ~ 0 0 0 0N - 0

ZO0 0 0 0 0 0

0 5d 0

4.- >-

0 Irl 'a - - 0

oa

o C0.4- ' 0 0 (\ 

-r 0 0 0 0

a..i

a) 0 rl C' E-'. - 0 ý- - (NJ

0 0 - 0r ~t- c. 0~a (D ( 0 0 0N 0~4'

- ~ - U - 0 - -c - 4.

- C -d '~

~0 0 0 ') 0 0 0

0 0 0 0 2 0 04a
350

THI TIE TII YO A I

3 0 i I I ... I

IGOOD :ONDITE N)

U!

1IWA TUNI

250

zW UN A CONDITION) I.Z 200 - ,,

u. A" SACO

u. SAKAI I IE

W 10 - z

UJ 10 ~1MZU!;HIMA(G4AVEL)

0____ ---TOKU fAMA(S , MD)

0 50 100 150 200 250 300 350

WATER CONTENT OF SLUDGE (.)

Figure 13. Result of dredging efficiency

errors 

(zone 

of 16 and 8 percent for the given values of 0M., m (zone A) and 1.0 m 8) in the zones of the efficiency study, respectively, after the opera- tors were familiarized with the operation procedures.

Figure 15 shows measurement and recording data obtained by an investiga- tion ship carrying the sonars cruising on the survey lines.

Therefore, in order to completely remove the given thickness of sediment to be dredged, it is necessary to remove about 20% more than said thickness of sediment. Such a high dredging accuracy can be attained because the dredge has a dredging mechanism that keeps the suction mouth parallel to the seabed

which 

during dredging as shown in Figures 10 and 12, unlike the cutterhead dredge slants to the seabed though this may vary depending upon the methoi of

management shown in Figure 14.

248
TIME MARK7 EI

TIME REQUIRED FOR CHANGING

LE F T _S W IN G _ _ _ _ _ _ _ _ _ _ _ _ __TIM E ) S W IN G D E R E C T IO N

LEFTSWIN DREOINGlst IME)RIGHT SWING DREDGING(bndTIM4E)

LEFT LIMIT UINE RIGHT UNIT LINE

=~SWING DIRECTION

DREDGED SOIL THICKNESS DREDGED SOIL THICKNESS

Figure 14. Sonar record (Zone B)

SEABED BEFORE DREDGING

SEABED AFTER DREDGING

(DRECORD OF LENGTHWISE SECTION

I 00 M

(B ZONE)

SRECORD OF T'RANSVERSE SECTIO N

40M 40_______

(B ZO NE) (A ZONE)

Figure 15. Seabed after dredging
CONCLUSIONS

This article has outlined the dredging test study of organic sludges in

Osaka Bay and the study on the Oozer pump dredge. Our findings based on this

test work are summarized as follows:

a. By fitting sonars to the upper side of the suction mouth and confirming the contours of the seabed, sludges may efficiently be

dredged along the ups and downs of the seabed.

b. While dredging, the operator can judge whether or not the operation

is being properly conducted by observing the contamination in the

vicinity of the suction mouth.

c. If the swing velocity is held at 6,- 7 m/min or less, little contamination occurs in the vicinity of the suction mouth.

d. At a swing speed of about 6 m/m.n, the efficiency of the dredge is

about 250 m 3/hr with a concentration ratio of about 30%.

e. By transporting the dredged sludge by a barge to the disposal site

and unloading it, disposal can be efficiently effected.

f. The Oozer pump does not suck in excess water while dredging the

sludge, making it possible to lessen the amount of slurry to be

disposed.

Under the circumstances, we believe that the Oozer type and the Clean-up

type dredges are suited for dredging and removing organic sludges. Although

acceptable results were obtained on the engineering method, efficiency, etc.,

for dredging and removing organic sludges by this test work, the disposal

method after dredging is an important subject to be solved for efficient removal and disposal of a considerable amount of sludges piled up over a wide

area in the Inland Sea. Therefore, investigation and study of a consistent

system of disposal, as regards dredging, transportation, and treatment of

sludges, should be conducted.

REFERENCE MATERIALS

Sea Environment Improving Pilot project (Sediment Cleaning Project) of the

Inland Sea, Execution, Scheme o'd Investigation Plan (Draft) Data Edition,

June 1979, the 3rd District Prrt and Harbour Construction Bureau, Transportation Ministry.

Sea Environment Improv'-; Pilot Project of the Inland Sea, Report on Dredging

Test and Investigation of Osaka Bay, March 1980, Kobe Harbour Construction

Office, the 3rd District Port and Harbour Construction Bureau, Transportation

Ministry, Corporate Juridical Person, Japan Dredging and Reclamation

Engineering Association.

250
Sea Environment Improving Pilot Project of the Inland Sea, Report on Dredging

Test and Investigation of Osaka Bay, August 1980, Kobe Harbour Construction

Office, The 3rd District Port and Harbour Construction Bureau, Transportation

Ministry, Corporate Juridical Person, Japan Dredging and Reclamation Engineering Association.

On the Execution, Scheme and Investigation of Sediment Cleaning Project of

the Inland Sea, HEDRO 1980, No. 19, by Yoshihisa Fujita.

Development of a New Type Suction Mouth for Swing Type Mud Dredgers, Iwai,

Kato, Niiyama, Tagaya, Shiota, Noguchi, Mitsubishi Heavy Industries, Ltd.,

Tec. Lab. Report Vol. 15, No. 4 1978-7.

Effective Removal of Soft Mud Layer by a Front-Open Type Drag Head, Okayama,

Hamada, Saito, Nakazono, Kato, Shirai Technical Note of the Port and Harbour

Research Institute Ministry of Transport, Japan.

251
AD P 0 0 2 6M ANAGEMENT TOOLS FOR ASSESSMENT

OF DREDGED MATERIAL IMPACTS

W. E. Pequegnat

TerEco Corporation

P. 0. Box 2848

College Station, Texas 77841

ABSIRACT

••The success of laboratory bioassays as diagnostic tools for assessing the

effects of environmental perturbations has been limited. It is proposed that

the adenylate energy charge coupled with analysis of selected metabolic enzymes

may overcome some of these limitations. The adenylate energy charge can be

calculated from concentrations of three adenine nucleotides: ATP + 0.5 ADP/ATP

+ ADP + AMP. Several studies demonstrate that the energy charge cani be a gauge

of environmental impact of importance to the survival of particular species.

Insights as to the cause of iripacts on the biota from complex mixtures such as

dredged material may be gained from analysis of test organisms fdr selected

.J . metabolic enzymes.7

INTRODUCTION

Maintenance dredging of harbor entrances and channels and the deepening of

ports to permit docking of deep-draft cargo vessels are essential tb the economic health of the United States and other nations. In spite of its importance, there are harbors in the U.S. where dredging is presently noý permitted

"while state authorities are attempting to establish realistic water-quality

criteria that must be maintained in harbor waters during the dredging/disposal

process. There are other areas where the Corps of Engineers cannotl undertake

dredging activities because of the presumed hazardous nature of the dredged material as determined by laboratory tests. The permitting processi generally

requires the carrying out of bioassays of the sediment to be dredgedl to determine its probable impact upon the biota of the dumpsite. The kindsi of bioassays to be carried out and the techniques to be employed are stipulated by the

U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers. At

the present time, the criterion of impact in the bioassay is the difference in

mortality between test organisms exposed to the sediment to be dredged and a

control sediment. One point of interest and concern to me is that laboratory

bioassays are poor simulators of field conditions and to my mind they have more

severe impacts upon the test species than the same sediments will have upon the

organisms resident at the proposed dumpsite. Another concern is simply that

using death of the test organisms gives us very little information on the

development of chronic responses. For these reasons, I am preparedl to recommend that (1) bioassays should be carried out in the field, and (2) that a

criterion other than death should be used to determine whether orl not test

organisms are under severe stress from dumped sediments. Thus, my objective is

to provide the environmental manager with a tool called the adenyl te energy

252
charge (EC) that will give him an insight into the significance of the biological impacts resulting from his schedule of dredged material disposal. Then I

plan to describe briefly a method for narrowing the possible cause or causes of

any severe stress that is observed from the EC analysis.

THE ADENYLATE ENERGY CHARGE

All the functions of organisms are controlled by rather specific enzymes

that are called metabolic enzymes. The adenylate energy charge (EC) is believed to be a primary factor regulating the activities of these enzymes. The EC

is thought to represent the metabolic energy potentially available from the

adenylate pool to an organism at the moment of sampling (Atkinson, 1968;

Atkinson & Walton, 1967). Its determination depends upon measuring from cellular extracts the concentrations of three adenine nucleotides (ATP): adenosine5'-triphospate, -diphosphate (ADP), and -monophosphate (AMP) and calculating

the EC ratio as follows: ATP + 0.5 ADP/ATP + ADP + AMP. By definition, the

ratio ranges from 0 to 1.0.

A healthy organism (an be expected to have an EC of 0.7 or above; however,

it is believed that growth or reproduction will not occur unless it, is 0.8 or

above (Atkinson, 1968; Chapman et al., 1971)., When it falls to 0.5, it can be

expected that the organisms will not recover when the impacting condition is

removed (Ivanovici, 1980b). When a ratio of 0.5 persists, death will inevitably follow (Behm & Bryant, 1975; Wijsman, 1976). The response of EC is rapid

(e.g. an exposure of 24 hours is adequate) and is more elucidating than

mortality data. For example, Ivanovici (1980a) working with a small marine

snail (Pyrazus ebeninus) found that when the EC dropped as a result of a

24-hour exposure to an impact, it did not drop further in the following three

days of the experiment (Table 1). /

APPLICATION OF THE ENERGY CHARGE TEST

TerEco Corporation studies off the coast of Louisiana for LOOP, Inc.,

investigated possible impacts of the discharge of brine solutions (8.6 times

salinity of normal seawater) on shrimp and other organisms (Pequegnat, 1981).

EC as well as selected metabolic enzyme tests have been carried out at 8

stations placed at distances ranging from a few meters to several nautical

miles away from the diffuser through which the brine derived from the water

excavation of a terrestrial salt dome (for oil storage) is discharged into the

ocean. EC data derived from the five field surveys conducted by TerEco between

October 1979 and May 1981 are presented in Table 2. Two points must be considered before these data can be interpreted. First, the initial four surveys

gathered benchmark data since they were carried out prior to the first

discharge of brine in April 1981. Second, during Surveys 1 and 2,test species

were exposed in the field for a period of 5 days, whereas in subsequent surveys

exposure time was reduced to 3 days.

Three important conclusions can be derived from the EC data in Table 2:

(1) the discharge of brine through the diffuser has had no important impact

upon the health of the grass shrimp (Palaemonetes pugo) and commercial shrimp

(Penaeus aztecus), (2) the EC response occurs within 3 days and possibly sooner

as noted above, and (3) a markel reduction of EC followed a drop in concentr.-

tion of dissolved oxygen (to l.ss than 1 ml/l) in the bottom water only. It

253
a i I I l~ i

TABLE 1. RESPONSE TIME OF THE ADENYLATE ENERGY CHARGE IN THE

G,"STROPOD PYRAZUS EBENINUS REDUCTION IN SALINITY AND

ELEVATED T1ER-ERAIikhAE IFIED FROM IVANOVICI, 1980a).

Sal ity Temperature Time of Adenylate

(o/oo) ("C) sample energy charge*

(days

0 20" 1 0.63 ± 0.07

4 0.66 ± 0.02

29" 1 C.51 ± 0.01

4 0.54 ± 0.03

1.7 20" 1 0.66 ± 0.03

4 0.66 ± 0.02

29" 1 0.55 ± 0.01

4 0.60 ± 0.04

34 20" 1 0.86 ± 0.02

4 0.89 ± 0.02

29" 1 0.73 ± 0.05

4 0.70 ± 0.01

• Values are means of 3 animals ± standard error

254
.. . . . . . . . . .

+1 +4 +1 1+4++ +1 + +f +i +i +f44+4 +f+1 +4 +4+4 4

IAA

U. SC , (vC )C D0C Ks0

ar MW 0 +4 +4 +1++44+1 +4+4 +1+4 +1 4A + +4 +4 +f+4 +1+4 +1+1

W <>E ..................

4n. . .. . . . . . . ..

ii1 -- C--

=0 LI 0 0 0 C

C) 0k.JC -(-

m 'm'

cc IA, -k~

X < - Cj 40 C) O CE - c,- (D8 P255
can be seen also in Table 2 that during Survey 3 the grass shrimp adapted

somewhat better than the commercial shrimp to the offshore, low-oxygen bottom

water that swept across the test area during the 3-day exposure period. The

average EC of grass shrimp exposed to the oottom water dropped to 0.34 (Table

2, Stations 7 and 8, B-BOMs) but was the same as the control in the oxygenated

surface waters (Stations 3 and 8, P-BOMs). The commercial shrimp had no survivors in the low-oxygen bottom waters at any station. There is other evidence

that EC responds by reduction below control values when environmental conditions deteriorate from optimal. For example, Ivanovici (1980b) found that the

EC of the snail Pyrazus ebeninus dropped significantly with change of tide and

even to a greater extent under abnormal flood conditions (Table 3). Wijsman

(1976) found that EC decreased in Mytilus edulis under anaerobic conditions.

Data are accumulating that show that EC responds to both natural and manmade perturbations. For instance, mollusks experimentally exposed to an

environment contaminated by petroleum hydrocarbons developed depressed ECs

(below 0.7), as did those exposed to the outlet stream of heated water (8*C

above ambient) from a power plant (Ivanovici, 1980a). In both cases, the low

ECs were associated with very sparse populations. This fact supports the

contention that low ECs are coupled with low reproductive and survival potentials.

METABOLIC ENZYMES

As indicated above for petroleum hydrocarbons and excess heat, the EC

drops rapidly under certain chemical or physical changes in the environment.

In many instances, however, it is not clear just what substance or substances

in a waste such as contaminated dredged material will cause the EC drop. In

some instances, this can be determined by analyzing the field test organisms

for selected metabolic enzymes (Pequegnat and Wastler, 1980). For instance,

the activity of the metabolic enzyme ATPase was found to change markedly (Table

4) in the presence of substantial amounts of PCBs in dredged material in the

New York Bight (Pequegnat and Wastler, 1980). Chlorinated hydrocarbons also

will cause a rapid drop in EC ratios. In like manner, anotner enzyme, namely

cytochrome P-420 and P-450, increases in organisms exposed particularly to

petroleum and chlorinated hydrocarbons, and catalase is particularly sensitive

to toxic metals. Thus, by these means it should be possible for the environmental manager to ascertain the class of toxic components of his dredged

material that may be causing a drop of EC in important species. Moreover, he

and the reguiatory agency should be reassured that irreparable damage is not

being done to the receiving environment so long as the EC remains at or above

0.7.

CONCLUSION

These findings elevate the EC to the important role of an early warning

system of stressful conditions, which are predictive of the development of

chronic conditions in the biota. This, then, can become an important tool for

the environmental manager who can adjust the rate of waste disposal into the

environment at levels that will permit the biota as a whole or key species to

retain their viability and reproductive capacities.

256
TABLE 3. PYRAZUS EBENINUS. AOENYLATE ENERGY CHARGE OF INDIVIDUALS

SAMPLED IN THE FIELD: NON-POLLUTED ENVIRONMENTS. VALUES

ARE MEANS OF N ANIMALS (INDICATED IN BRACKETS). MOLLUSCS

FREEZE-CLAMWED IN THE FIELD (FROM IVAMOVICI, 1980b).

AEC

Sample High tide Low tide

Population from Jervis Bay

Normal conditions:

July 1975 (5) 0.90 0.79

Oct. 1975 (10) 0.86 0.80

July 1976 (5) 0.87 0.80

± 0. 014

Abnormal conditions:

Flood (12) 0.65 ± 0.034

Population from Port Hacking (6)1 0.85 ± 0.02

257
TABLE 4. ATPase LEVELS IN FUNDULUS GRANDIS LIVER AFTER 7 DAYS

EXPOSURE ON THE BOTTOM (IN F-IWM CAGES) IN THE NEW YORK MUD

DUMPSITE*

No. of ATPase

Location fish units** x Standard

analyzed 10- 4 /mg

protein deviation 10-

8-BOM upstream of Dumpsite 33 12.400 .0004

B-BOM in Dumpsite 35 4.000 .0002

1 Mile downstream of Dumpsite 32 9.100 .0003

* In this table, analysis of variance was used to evaluate the data

** Bergmeyer Unit for ATPase amount of enzyme needed to decompose 1

g of NADH (Nicotinamide adenine dinucleotide reduced form) in 1

min

258
LITERATURE CITED

Atkinson, 0. E., 1968. Citrate and the citrate cycle in the regulation of

energy metabolism. Biochem. Soc. Symp. 27, 23-40.

Atkinson, 0. E. & Walton, G. M., 1967. ATP conservation in metabolic regulation. J. Biol. Chem. 242, 3239-3241.

Behm, C. A. & Bryant, C., 1975. Studies of regulatory metabolism in Monieza

expansa: General considerations. Int. J. Parasitol. 5, 209-217.

Chapman, A. G., Fall, L. & Atkinson, 0. E., 1971. Adenylate energy charge in

Escherichia coli during growth and starvation. J. Bact. 108, 1072-1086.

Ivanovici, A. M., 1980a. The adenylate energy charge in the estuarine mollusc,

Pyrazus ebeninus. Laboratory studies of responses to salinity and temperature. Comp. Biochem. Physiol. 66A, 43-55.

Ivanovici, A. M., 1980b. Application of adenylate energy charge to problems of

environmental impact assessment in aquatic organisms. In: Otto Kinne & H.

P. Bulnheim (eds.) Helgolander Meeresuntersuchen, Vol.73, p. 556.

Pequegnat, W. E., 1981. Baseline study of the effects of brine disposal on

selected marine animals. Final Rept. on Survey No. 5 to LOOP, Inc. TerEco

Corporation, College Station, Texas, 77841.

Pequegnat, W. E. and Wastler, T.A,. 1980. Field bioassays for early detection

of chronic impacts of chemical Nastes upon marine organisms. In: Otto Kinne

& H. P. Bulnheim (eds.) Helgolander Meeresuntersuchen, Vol. 33,-p. 531.

Wijsman, T. C. M., 1976. Adenosine phosphates and energy charge in different

tissues of Mytilus edulis under aerobic and anaerobic conditions. J. Comp.

Physiol. -1.

259
1>

PURIFICATION OF WATER AND SEDIMENTS USING ORGANISMS (LIVING FILTER)--

REMOVAL OF SUSPENDED SOLIDS AND NUTRIENTS BY

PHRAGMITES COMIIUNIS T. AND ZOSTERA MARINA L.

Tadashi Otsuki

Japan Dredging and Reclamation

Engineering Association

Toranomon 1 - 2 - 8, Minato-ku,.

Tokyo 105, Japan

ABSTRACT

"--&In order to clarify the purification efficiency

of removal of SS (suspended solids) and nutrients in

seawater by Phragmites communis T. and Zostera marina

L., experiments were carried out to determine the

correlations between the removal rates for three conditions: (1) the differences of flowing down systems

(cascade vs maze system), (2) the volume of flowing

water (3 flow conditions), and (3) the concentrations

of SS in both planted and nonplanted test ponds.

The following methods are generally cousidered

more desirable for purification of the water:

a. For removing SS and nutrients, the flowing down

method using the cascade type ponds under less

volume of flowing water,

b. For removing nutrients, the flowing down method

controlling the volume of flowing water to

remain for 8 - 10 days:.

c. For removing P04-P, a filtrating process

"using sand-gravel layers.-

INTRODUCTION

Many studies on the purification of water and sediments using aquatic

plants, Scirpus lacustris L., Phragmites communis L., and Eichhornia

260
crassipes S., etc., have been conducted since the late 1940's, in Western

Germany and in the U.S.A.l-). Most of these investigated wainly the eu

trophied lake water, urban sewage, industrial drainage, or contaminated

sludges; few investigations of the polluted water and contaminated sediments

in the sea have been carried out, and there are still many problems to be

solved in this area.

Furthermore, although several studies on the absorption efficiency of

(6, 7) nutrients in seawater using sea weeds have already been done in Japan

the removal rates of nutrients in seawater by. Phragmites communis and Zostera

marina, which were flourishing in brackish water at the coastal zone, have

scarcely been studied as yet.

In this study, in order to clarify the purification efficiency of removals of SS and nutrients in seawater by Phragmites and Zostera, experiments

were carried out to determine the correlations between the removal rates for

three conditions: (1) the differences of flowing down systems, (2) the

voluine of flowing water, and (3) the concentrations of SS in both planted and

nonplanted test ponds (May-Oct., 1979 and 1980).

MATERIALS AND METHODS

Aquatic Plants

Aquatic plants used in this study, Phragmites communis and Zostera

marina, had respective body lengths of about 97 to 177 cm (average 140.3 cm)

and 53 to 86 cm (average 68.8 cm); the respective body wet weights were about

15 to 50 g (average 29.4 g) and 4 to 21 g (9.1 g); and the respective densi2 2 ties planted were 13 roots/mi and 20 roots/m . Thick vinyl packing tape was

used as the para-Phragmites communis and the para-Zostera marina for the control experiments. This tape simulated the leaf action of the plants.

Seawater

Seawater used in this study was drawn from a well and fixed concentrations were added of kaolin for SS, and of KH 2PO (NH4)2 SO4, NaNO KNO 3 and

HOOCCH2CH2CH (NH 2) COOH for autrients (Table 1).

Facilities

Facilities used in this study were composed of a cistern for stirring up

the seawater (10.0 m x 7.0 m X 1.2 m, equipped with two stirring apparatuses),

a tank tower for pouring into (0 0.3 m, height 3.2 m, depth 1.6 m), a cascade

261
TABLE 1. QUALITIES OF SEAWATER DRAWN FROM A WELL

Items Characteristics

Temperature 18.3 - 18.7 0 C

Cl- 15.89 - 16.68%

PH 8.2 - 8.4

DO 52 - 65%

COD 0.0 - 0.2 ppm

NH4-N 0.020 - 0.040 ppm

NO2-N 0.002 - 0.006 ppm

NO 3-N 2.700 - 5.260 ppm

Inorg.-N 2.722 - 5.306 ppm

PO 4-P 0.090 - 0,.300 ppm

type test pond (1.4 m x 15.0 m X 1.25 m), and a maze type test pond (10.0 m

x 7.0 m x 1.2 m, width of a water way (i.0 m), and length of a waterway

(60.0 m); their arrangements and a detailed section of the cascade type test

pond are shown in Figs. I and 2. In the cascade type test pond, pits

(1.5 m x 0.6 m x 1.25 m) were established both on the upper and lower sides

of each small test pond (1.5 m x 2.0 m x 1.25 m), and heads of 10 to 20 cm

were made, respectively. In the bottom of each small test pond, sand-gravel

or sands, respectively, were laid to fixed thickness according to the purpose

of experiments; vinyl chloride tubes with slits (diameter = 10 cm, length

1.5 m) were embedded for underdraining.

Methods and Conditions

For every SS and nutrient removal experiment, the seawater used was

stirred in the cistern and pumped into the tank tower for cventual pouring into

the cascade or maze type test pond. The volume of flowing water was controlled

with the cock valve. In the continuous surface flow and filtration experiments, the water flowed continuously during the fixed time, and was sampled

and measured once just before the conclusion of each experiment. However, in

the static water experiments, the water was sampled and measured 6 times (after

0, 0.5, 1, 3, 4, and 7 days) in the nonacclimated experiments and 11 times

262
10 0 1"

0..O

4St 3

0 0 .a

CL

Figur 2. Scino mhascae type test pond

263
(every day) in experiments acclimated for 2 days. The item of water quality

measured were temperature, Cl-, pH, DO, and SS in the removal experiments of

SS, and temperature, Cl-, pH, DO, NH 4 -N, NO2 -N, NO3 -N, Inorg -N, PO4 -P, and

COD in the removal experiments of nutrients. The contents of each experiment

are discussed in the following paragraphs.

Removal Experiments of SS

Continuous surface flow experiments in the cascade type test pond. The

conditions of the experiments and the small test ponds used were set up as

shown in Table 2. The concentrations of SS were 100, 300, and 500 ppm; the

TABLE 2. REMOVAL EXPERIMENTS OF SS - CASCADE TYPE TEST POND

Volume of

Concentrations flowing water

of SS (m3 /hr) Time

(ppa) (flow) (hr) Plants* Test ponds**

0.5 6.0 Phragmites

1.0 3.0 communis All BI

2.0 1.5

100 0.5 6.0 Para-P.t A2

1.0 3.0 communis and

300 2.0 1.5 and 2

No Plants

and

1.5 6.0 Zostera

500 3.0 3.0 marina Div E1

6.0 1.5

1.5 6.0 Para-Z.j D2

3.0 3.0 marina and

6.0 1.5 and E

No Plants

*Densities planted: 13 roots/m2 in Phragmites, 20 roots/m2 in Zostera.

.*A Water depth: 35 cm in Phragmites and 80 cm in Zostera.

t Control experiment using vinyl tape to simulate the action of the grasses.

33

volumes of flowing water were 0.5, 1.0, and 2.0 m3 /hr in Phrsgmites and 1.5,

3.0, and 6.0 m3 /hr in Zostera; and the terms of the experiments were 6.0, 3.0,

and 1.5.hr, respectively. With the following conditions, 3 concentrations,

3 flow/time combinations, 4 plant conditions, a total of 36 experiments were

conducted.

264
Continuous surface flow experiments in the maze type test pond. Only

Phragmites communis was used in this study. The conditions of the experiments

were set up as shown in Table 3.

TABLE 3. REMOVAL EXPERIMENTS OF SS - MAZE TYPE TEST POND

Volume of

Concentrations flowing water

3 of SS (m /hr) Time (ppm) (flow) (hr) Plants

5 10.0 Phragmites

10 5.0 communis

100 15 3.5

and 5 10.0

500 10 5.0 No

15 3.5

The concentrations of SS were 100 and 500 ppm; the volumes of flowing

water were 5, 10, and 15 m 3/hr, and the terms of the experiments were 10.0,

5.0, and 3.5 hr. With the following conditions, 2 concentrations, 3 flow/time

combinations, 2 planting conditions, a total of 12 experiments were conducted.

Removal Experiments of Nutrients

Continuous surface flow experiments. In the cascade type test pond,

the conditions of experiments and the small test ponds used were set up as

shown in Table 4. The concentrations of nutrients were fixed; the volumes of

flowing water were 0.125, 0.25, and 0.5 m 3/hr in Phragmites and 0.375, 0.75,

and 1.5 m 3hr in Zostera; and the terms of the experiments were 24, 12, and

6 11r. respectively. With the following conditions, 1 concentration, 3 flow/

time combinations, 4 planting conditions, a total of 12 experiments were

conducted.

In the maze type test pond, the conditions of experiments were set up

as shown in Table 4. The concentrations of nutrients were fixed; the volumes

of flowing water were 5, 10, and 15 m 3/hr, and the terms of the experiments

were 10, 5, and 3.5 hr, respectively. Only Phragmites was used in this study.

With the following conditions, I concentration, 3 flow/time conditions,

2 planting conditions, a total of 6 experiments were conducted.

265
TABLE 4. REMOVAL EXPERIM ENTS OF NUTRIENTS -

CONTINUOUS SURFACE FLOW EXPERIMENTS

Volume of

Concentrations* flowing water

of nutrients (m 3/hr) Times (ppm) (flow) (hr) Plants Test ponds

0.125 24.0 Phragmites

0.250 12.0 coiunuis A., B1

0.500 6.0

The

0.125 24.0

0.250 12.0 No cascade A2 , B2

(NH 4) 2S4 2, 0.500 6.0

type

0.375 24.0 Zostera

N aNO2 2, 0.750 12.0 marina test DI ,•

1.500 6.0

pond

KNO3 2, 0.375 24.0

S0.750 12.0 No D2Y E2

1.500 6.0

KH2PO4 2, 5.000 10.0 Phragmites

10.000 5.0 communis The maze

15.000 3.5

type test

5.000 10.0

10.000 5.0 No pond

15.000 3.5

Filtration experiments. Only Phragmites was used in this study. The

conditions of experiments and the small test ponds used were set up as shown

in Table 5.

The concentrations of nutrients were fixed; the volumes of flowing

water were 0.125, 0.25, 0.5, 1.0, 3.0, and 5.0 m 3/hr in sand-gravel layers

(each thickness 20 cm) and 1.0, 2.0, and 3.0 m 3/hr in sand layers (thickness

.40 cm); and the terms of the experiments were 24, 12, 6, 10, 3.5, and 2 hr

and 1J, 5 and 3.5 hr, respectively. As per Table 5, a total of 18 experiments

were conducted.

266
TABLE 5. REMOVAL EXPERIMENTS OF NUTRIENTS -

FILTRATION EXPERIMENTS

Volume of

Concentrations flowing water

of nutrients (m 3/hr) Times Test Filtration

(ppm) (flow) (hr) Plants ponds layers

0.125 24.0

0.25 12.0 Phragmites At BI

0.5 6.0 communis

(NH4 ) 2 So4 2, 1 10.0

3 3.5 A2, B2

N aNO 2, 5 2.0 Sand-gravel

0.125 24.0

KNO3 2, 0.25 12.0 A2, B2

and 0.5 6.0 NO 1 10.0

KH2PO4 2 3 3.5 All BI1 5 2.0

1 10.0 Phragmites

2 5.0 communis D E

3 3.5 2 2

sands

1 10.0

2 5.0 No Di, E1

3 3.5

Static water experiments. The conditions of experiments and the small

test ponds used were set up as shown in Table 6. The concentrations of nutrients were fixed, and the terms of the experiments were 7 days in the

nonacclimated experiments (both Phragmites and Zostera) and 10 days in the

acclimated experiments (only P!bramites). As per Table 6, a total of 6 experiments were conducted.

267
TABLE 6. REMOVAL EXPERIMENTS OF NUTRIENTS -

STATIC WATER EXPERIMENTS

Concentrations

of nutrients Times

(ppm) (days) Plants Test ponds

(NH 4 )2So 4 2, Phragmites

N aNO2 2, communis Alt B1

KNO 3 2, 7

and No A2

KH2PO4 2 24 Zostera DI, El

marina

No D2

(NHt 4 ) 2 S0 4 2, Phragmites

NaNO2 2, communis D2' E2

KH KNO 2PO 4 2,2?2, 10

and

HOOCCH 2 CH2- DI

CH(NH2 )COOH No

20,

RESULTS

Pesults obtained in this study are discussed below.

Removal Rates of SS

Continuous Surface Flow Experiments in the Cascade Type Test Pond

In the cascade type test pond, the SS removal rates by Phragmites communis

and Zostera marinh obtained in this study are shown in Figure 3.

2

The Phragmites SS removal rates at 3 and 6 m in planted flowing down

areas were, respectively, 49.6-62.7% and 84.1-89.5% in 0.5 m 3/hr, 25.1-44.1%

and 56.1-66.6% in 1.0m 3/hr, and 9.6-33.6% and 27.8-45.5% in 2.0 m3/hr ofthe

volume of flowing water. There was a tendency for the rates to show higher

values according to higher concentrations of SS and less volume of flowing

water. This tendency was especially noticeable in the first 3-m2 areas

planted. The differences of removal rates in each concentration of SS were

2 2 larger according to more volume. At 3 m rather than 6 m2, the differences

268
CASCAOE TYPE MAZE TYPE

Ph rarn, tes Zostera IInraogrm tes

100

040 5M3,hr I 5m 3/hr 0 5m3/hr - I" l 3/hr -3m 3/hro, -- 10'"3thr

*lih 3 3,

* • 0• a2m3 /hr /h . 6M /hr *- 0 15m3 ,,hr

I. O/ " •

-50 :.

E

0 3 6 0 3 6 0 1 C3-o5c

Plot Surface Ar'ea (m2)

- 100P m *... -- .300.* .-- 5 X P M

Figure 3. Removal rates ofSS

between 100 and 300 pp. were 2.7-5.21 in 0.5 a 3/hr, 10.5-11.2% in 1.0 m 3hr,

and 9.6-12.8% in 2.0 m 3/hr, and the differences between 100 and 500 ppm were

5.4-13.1% in 0.5 m 3/hr, 10.5-19.0% in 1.0 a 3/hr, and 17.7-24.0% in 2.0 m 3/hr,

respectively.

The SS removal rates in nonplanted test ponds were lower than in the

planted ponds, and their differences were 26.1-33.4% in 0.5 t 3/hr, 17.2-

26.7% in 1.0 m 3 /hr, and 13.7-17.9% in 2.0 m.3 /hr at 6 t2 of flowing down areas.

The differences tended to be larger according to less volume, on the order of

300 > 100 > 500 ppm in the concentrations of SS. The rates in para-Phragmites

were lower than in planted, and their differences showed higher values of

18.9-22.7% in 500 ppm" however, they were scarcely detected in 100 and

300 pp,.

In this stud), the temperature was 21.8-25.4*C, Ci was 15.91-16.89 /00,

pH was 7.5-8.6, and DO was 88-105%, respectively; pH especially tended to

show lower values of 0.2-0.6 in planted test ponds.

On the other hand, the Zostera SS removal rates at 3 and 6 m2 of planted

flowing down areas were, respectively, 7.9-50.3% and 31.6-73.0% in 1.5 m 3/hr,

5.2-26.9% and 17.9-42.9% in 3.0 3/hr, and 2.1-17.0% and 7.9-29.5% in 6.0 m3 /hr

of the volume of flowing water. There was a tendency similar to Phragmites

with the rates showing higher values according to higher concentrations of SS

and less volume. This tendency was especially noticeable in the first

269
3-m2 are.s planted in 500 ppm. However, their removal rates showed lower values compared with Phragmites according to lower concentrations of SS; the differences were 7.5-57.9% in 100 ppm, 15.9-37.1% in 300 ppm, and 11.1-17.2%, in

500 ppm, respectively. Contrary to Phragmites, the differences of removal

rates among each concentration of SS were generally less according to more

2 2 volume and in first 3 m2 than 6 m . The differences between 100 and 300 ppm

were 17.1-28.9% in 1.5 m3 /hr, 8.3-11.6% in 3.0 m3 /hr, and 2.8-4.4% in 6.0

m3 /hr; between 100 and 500 ppm the differences were 41.4-42.4% in 1.5 m3 /hr,

3 3 21.7-25.0% in 3.0'm /hr, and 14.9-20.9% in 6.0 m /hr, respectively.

The SS removal rates in nonplanted test ponds showed lower values than

in planted ponds, and the differences at 6 m2 were 8.3-27% in 1.5 m3 /hr,

6.8-19.9% in 3.0 m 3/hr, and 3.4-15.8% in 6 m3 /hr. The differences tended

to show higher values according to less volume and higher consistencies of

SS. Also, the differences of removal rates of SS between planted and para-"

planted test ponds were 12.1-18.3% at 3 m2 in 500 ppm; however, the differences were scarcely detected in other cases.

In this study, the temperature was 22.5-25.4 0 C, Cl- was 16.15-16.860 /oo,

pH was 7.6-8.6, and DO was 92-100%, respectively.

Continuous Surface Flow Experiments in the Maze Type Test Pond

In the maze type test pond, the SS removal rates by Phragmites communis

are shown in Figure 3.

While the SS removal rates showed higher values accteding to less

volume of flowing water, the 500 ppm rates (rather than 100 ppm) showed .ery

high values, especially in the early areas of 10 and 20 m2 (St. I and 2,

Figure 1); however, they scarcely increased in the latter areas of 40 and

50 m2 (St. 4 and 5, Figure 1).

Although 2 lower values of 4.4-11.6% were found in 100 ppm at 30 m in

every volume, the rates tended to increase relatively from 40 to 50 m , and

33 3 2 they were 29.1% in 5 m /hr, 16.5% in 10 m /hr, and 10.9% in 15 m /hr at 50 m

respectively. On the contrary, in 500 ppm in the early areas, rates tended

to show very high values according to less volume, especially of .•3.6% at

10 m2 and 76.9% at 20 m2 in 5 m 3/hr; however, they increased only slightly

from 30-50 m 2, from 84.9-88.6%. Furthermore, they were, respectively, 72.0%

in 10 m3 /hr and 59.7% in 15 m3 /hr at 50 m2.

270
Although the rates iv nonplanted test ponds showed lower values than in

planted, their differences were less according to more volume in both 100 and

500 ppm.

In this study, the temperature was 13.9-18.7*C, Cl- was 15.48-17.11 /o-ý,

pH was 8.0-8.4, and DO was 100-105%, respectively.

Removal Rates of Nutrients

Continuous Surface Flow Experiments

In the cascade type test pond, the removal rates cf nutrients by

Phragmites communis and Zostera marina obtained in this study are shown in

Figure 4.

PH,t-N NO2-N NO,-N Inorgý-N PO,-P

100 -

o 0

50 0

I -A

"-I6- 0 36 03/a 0 36 03 6

Plot Surface Area (in 2)

Phragmites: oO.125m 3/hr a 0.25m3/hr a 0.5M3/hr

Zostera: * 0.375m 3/hrA 0.75M3/hr a 1.5M 3/hr

Figure 4. Removal rates of nutrients, cascade type test pond

In Phragmites N`H4-N showed ver" uigh removal rates of about 100.0% in

0.125 m 3/hr, 51.4% in 0.25 m3/h:, and 81.9% in 0.5 m 3/hr; NO2 -N also showed

high values of 53.7% in 0.12., m 3/hr, 24.2% in 0.25 m 3/hr, and 87.6% in

0.5 m 3/hr at 6 m 2, respectively. However, no regular correlation was detected

between removal rates and flow. On the contrary, NO3 -N showed very low values

271
of removal rates in every flow rate. Inorg.-N values (summed NH4 -N, NO2 -N,

and NO 3 -N) were 8.5% in 0.125 m 3/hr, 12.1% in 0.25 m 3/hr, atJ 37.3% in

3 2 0.5 m /hr at 6 m . There was a tendency for the rates to show higher values

according to more volume within the range investigated in this study. The removal of P04-P was scarcely detected in 0.125 m 3/hr; however, the rates showed

3 3 2

very high values of 40.5% in 0.25 mi/hr and 61.6% in 0.5 mi/hr at 6 m . Like

Inorg.-N, the rates showed higher values according to more volume.

Furthermore, with respect to the differences of removal rates between

planted and nonplanted test ponds, although NH4 -N and NO 2-N showed higher

values of 18% and 6.8-64.0%, respectively, such differences were scarcely

detected in NO3 -N, Inorg.-N, and PO -P

On the other hand, Zostera removal rates were generally lower compared

with Phragmites, and although the rates of NH 4-N showed high values of 66.7%

in 0.375 m3 /hr, they showed low values of 17.3% in 0.75 m3 /hr and 3.3% in

3 2 1.5 m /hr and 6 m . There was a tendency for the rates to decrease according

3 to the volume increases. NO 2-N showed a high value of 22.7% in 1.5 m /hr,

but the removals were scarcely detected in 0.375 m3 /hr and 0.75 m3 /hr. No

regular tendency was recognized between the removal rates and the volume of

flowing water. NO 3-N showed relatively low values in every volume, and the

rates tended to increase according to the volume increasing. Inorg.-N had a

similar tendency.

Withrespect to the differences of removal rates between planted and

nonpianted test ponds, in every case the differences were Scarcely detected

in 0.375 m 3 /hr; however, there were a few differences: NH4 -N showed 5.3% in

0.75 m3 /hr and 13.0% in 1.5 m3 /hr, Inorg.-N 4.0-4.4% in 0.75 m3 /hr and

1.5 m3 /hr, and PO4-P 9.3% in 1.5 m3 /hr, respectively.

In this study, the temperature was 23.1-25.5*C, Cl was 17.00-17.89o/oo,

pH was 7.8-8.7, and DO was 74-105%, respectively.

In the maze type test pond, the removal rates of nutrients by Phragmites

communis obtained in this study are shown in Figure 5.

All removal rates of nutrients showed gradually higher values according

to the -increasing flowing down areas in the lower flow conditions. Although

this tendency was more noticeable, it was scarcely detected for NH4 -N and

NO 2- which showed, respectively, very low values in every flow condition.

272
20 NH,-N N0 2 -N N0 3 -N

10

A0

10 50 0 203040 " 0 10 203040 50 1 33 Q/ 04R 10 50

0

E 20 Inorg.--N PO, -P o 5m 3 /hr

o 15m 3 /hr

10 0.,,, 0..o 0o- , a 15m 3/hr

0 10 203040 50 0 10203 50

Surface Area of Test Plot (M2).

Figure 5. Removal rates of nutrients, maze type test pond

Also, NO 3-N, Inorg.-N, and P04-P, respectively, showed low values of 13.8,

7.7, and 6.8%; 11.0, 6.6, and 3.8%; and 14.0, 8.0, and 5.4% in 5, 10, and

3 2 15 m /hr at 50 m . The rates tended to decrease gradually as the flow

increased.

With respect to the differences between planted and nonplanted test ponds,

all nutrients except NH 4 -N showed higher removal in planted ponds as the flow

decreased. In this study, the temperature was 17.8-23.01C, C1 was 15.11-

17.390/oo, pH was 8.0-8.4, and DO was 98-105%, respectively. Also, pH

especially tended to decrease gradually to about 0.1-0.3 in planted test ponds

as the areas of flowing down increased.

Filtration Experiments

Sand-gravel layer. By filtrating the sand-gravel layers planted with

Phragmites coomunis, the nutrient removal rates shown in Figure 6 were

obtained.

273
The nutrient removal rates of NH4 -N, NO2 -N, and PO4 -P tended to decrease

gradually as the flow increased, but the opposite was true for NO 3-N and

Inorg.-N. The removal rates of NH4-N showed very high values of 86.0% in

0.125 m3 /hr, 50.4% in 0.25 m3 /hr, and 45.0% in 0.5 m3 /hr at 6 m2; and NO2-N also

showed high values of 44.3% in 0.125 m 3/hr, 43.5% in 0.25 m 3/hr, and 20.8% in

3 0.5 m /hr. However, the removals of both nutrients were scarcely detected

over their volumes. While the removal rates of PO4-P showed very high values

of 90.8-91.2% in 0.125, 0.25, and 0.5 m3 /hr, they also showed high values of

61.4% in 1.0 m 3/hr, 20.1% in 3.0 m3/hr, and 14.6% in 5.0 m 3/hr. These results

suggested that the filtration layers were very effective methods for purification. The rates of NO 3-N and Inorg.-N were only 2.5-7.5% and 4.4-15.8%,

respectively.

The differences in removal rates between planted and nonplanted test

ponds were scarcely detected in NH4 -N, NO2 -N, and NO 3-N, and there were lower

differences for a smaller volume of flowing water. On the other hand, in

PO4 -P some differences were detected in a higher volume of flowing water.

In this study, the temperature was 18.5-24.3*C, C1- was 16.29-17.63°/oo,

pH was 7.0-8w6, and DO was 25-104%, respectively. Also, pH decreased to

about 0.5-1.3 in planted and 0.1-1.2 in nonplanted test ponds, respectively, by filtrating, and the tendency was more remarkable in less volume

of flowing water. At the same time, it was also recognized that DO decreased

to about 26-77% in 0.125-0.5 m 3/hr in both planted and nonplanted test

ponds by filtrating.

Sand layer. By filtrating the sand layers planted with Phragmites

communis, the nutrient removal rates shown in Figure 6 were obtained.

The removals of NH4-N, NO2 -N, add NO 3-N were scarcely detected in every

volume by filtrating; however, the rates of PO4 -P showed higher values of

33 3 2

60.% in 1.0 m /hr, 43.2% in 2 m /hr, and 39.7% in 3 m3 /hr at 6 m , similar to

sand-gravel layers in less volume of flowing water. Although the differences

of removal rates between planted and nonplanted test ponds were scarcely detected for NH4 -N, No2 -N, and NO 3-N, the rates of PO 4-P showed higher values

in planted test pcnds.

In this study, the temperature was 18.5-22.0 0 C, C1_ was 16.29-17.270/oo,

pH was 7.4-8.4, and DO was 98-104%, respectively. The pH decreased to the

extent of about 0.6-1.0 by filtrating.

274
100 NIK-N N02-N N03-N Inorg.-N PO4-P

0 Sand-gravel layers 0/

o 0.125m3/hr /

e 0.25m 3/hr

50. A 0.5m3/hr

, A 1 m3/hr

"// a 3m 3/hr

4,/I * 5m 3/hr

A A/

0

036 036 0 36 036 06

1 Sand layers 0

o 1m3 !hr

A 2m 3/hr 0

50 t 3m 3/hr 0

036 036 036 036

3 6

Surface Area of Test Plots (M2 )

Figure 6. Removal rates of nutrients, filtrating experiments

275
Static Water Experiments

The nutrient removal rates in static seawater, by Phragmites communis

and Zostera marina, obtained in this study are shown in Figure 7.

100. NH 4-N ot:-§ o Inorg.-N a50./10.0

01 2345678910 01 2345678 910

S100 0

, - - ' P O 4 -- P

r 0

2 -,.. /N0 P0.,--

0 50 --/0 aE 01 23 4,5 6 7 8 9 10 01 23 4 5 6 78 910

1 N0 3-N 0 0 D

5O- -/ 0.?

01 234 56 78 910 01 23 4 5 6 78910

Remaining days (days)

o Phragmites nonacclimated

* Zostera nonacclimated

o Phragmites acclimated

Figure 7. Removal rates of nutrients, static water experiments

In the nonacclimated static water experiments, in both Phragmites and

Zostera, the rates of Inorg.-N and PO 4-P increased for a time it. the Ist day,

then decreased to the 3rd day, and again increased sharply from the 4th to

7th day. While Phragmites compared with Zostera showed relatively higher

values, the rates of Inorg.-N and PO4 -P showed very high values of 95.7 and

276
69.3% in Phragmites and 75.4 and 56.3% in Zostera during 7 days, respectively.

On the other hand, in the static water experiments using Phragmites

acclimated for 2 days, the rates of Inorg.-N increased gradually from the

2nd day and sharply from the 6th to 8th day, and again gradually inclined to

the 10th day. PO4 -P increased in some degree to the 2nd day, decreased to

the 3rd day, increased sharply from the 3rd to 6th day, and gradually

inclined from the 6th day. COD increased sharply to the 2nd day and gradually inclined from the 2nd to 10th day. The rates of Inorg.-N, PO4-P, and

COD showed high values of 84.2, 74.3, and 76.5% during 10 days, respectively.

Thus, in acclimated experiments compared with nonacclimated, the

gradually inclining or declining terms were shorter in the early days and the

curves of removal rates increasing were gentler. Furthermore, the differences

between planted and nonplanted test ponds, in Phragmites and Zostera nonacclimated, showed higher values of 53.5 and 74.7% in Inorg.-N, and 40.1 and 36.2%

in PO 4-P on the 7th day, respectively. However, in Phragmites acclimated, the

differences were scarcely detected, about 9.4% in Inorg.-N, 5.9% in PO.4-P, ' 4

and 10.8% in COD on the 10th day.

In this study, the temperature was 16.2-22.9*C, Cl" was 15.74-18.19°/oo

in nonacclimated and 7.92-10.49°/oo in acclimated, pH was 7.7-9.3, and DO

was 48-105%, respectively. In Phragmites test ponds, pH decreased to about

0.4 in the early days, and DO showed lower values of about 48.0-74.5% around

the 2nd-3rd day and the 9th-10th day.

CONCLUSIONS AND DISCUSSION

In this study, in order to clarify the purification efficiency of

removal of SS and nutrients in seawater by Phragmites communis and Zostera

marina, experiments were carried out to determine the correlations between the

removal rates for three conditions: (1) the differences of flowing down

systems, (2) the volume of flowing water, and (3) the concentrations of SS

in both planted and nonplanted test ponds, under fixed densities of

13 roots/m2 in Phragmites and 20 roots/m2 in Zostera.

Higher removal rates were detected in narrow areas in the cascade type

test ponds, and Zostera rates showed lower values in lower concentrations of

SS. However, in every case, the rates showed higher values in less volume of

277
I I II l l l -

"flowing water, in higher concentrations of SS, and in larger areas of flowing

down. In the maze type test pond planted with 13 roots/m2 of PLagmites, the

following correlation formula was developed among the removalirates of SS

3

(Rs:%), the volume of flowing water (Q:m /hr), the areas of flowing down 2

(A:m), and the concentrations of SS (N:ppm):

AA- 6 /A.N\2_ .9 -10(AN3

RSS = -5.4982 + 0.0459 - 4.7884 x -- - x 10

(standard deviation of residual 4.8637)

On the other hand, as for the removal rates of nutrientsl, in the surface

flow experiments, higher values of a few times were detected An the cascade

type as compared to the maze type test pond. The considerably higher values

were especially detected in 0.5 m3 /hr in the cascade type and in 5 M3 /hr in the

maze type test pond. The rates of PO4 -P also showed generall higher values

than Inorg.-N; this tendency was more noticeable in the cascade test pond.

In the maze type test pond planted with Phragmites, the following correlation formula was among the removal rates of Inorg.-N (R%) and P04 - P

3 (Rp:%), the volume of flowing water (Q:m /hr), and the areaslof flowing down

2 (A:m.):

S0.1552 - o.1940(ý) + 0.5747()2- 0 3

(standard deviation of residual 0.5461)

Rp -4.7279 + 1.0617(A) + O.2550( - 0.0183

(standard deviation of residual 0.8420)

In the filtrating experiments, in both sand-gravel and sand layers, the

rates of PO4 -P removal showed very high values of about 91% in less volume of

flowing water, 0.125-0.5 m3 /hr; however, the values decreased gradually as

278

II I I I II I
the volume increased. In sand-gravel layers, the removals of NH4 -N and NO 2-N

were detected in 0.125-0.5 m 3/hr, but in sand layers, they were scarcely

detected in every case of NH4 -N, NO2 -N, NO 3-N, and Inorg.-N.

In the Static water experiments, the removal rates of nutrients increased gradually with the lapse of time: every case showed very high values

after the 7th-8th day, and it was found that the rates of Inorg.-N, P04 -P,

and COD showed very high values of 84.2, 74.3, and 76.5%, respectively, on the

10th day. The differences of removal rates between planted and nonplanted

test ponds were scarcely detected. In planted test ponds pH declined to the

neutral side.

In the static seawater tests planted with Phragmites the following correlation formula was developed between the removal rates of Inorg.-N (RN:%),

PO4 -P (Rp:%), COD (RCOD:%), and remaining days (D:days).

RN= 21.8587 - 18.7148D + 5.5525D 2 0.3040D3

(standard deviation of residual 12.4444)

Rp ='30.8557 - 21.1121D + 6.4850D 2 - O.3976D3

(standard deviation of residual 5.9626)

23 R = -6.7443 + 23..7050D - 2.6741D2 + 0.1146D3

(standard deviation of residual 2.6447)

From these results, the following methods were generally considered more

desirable for purification of the water: (1) flowing down method using the

cascade type ponds under less volume of flowing water for removing SS and

nutrients; (2) flowing down method controlling the volume of flowing water to

remain for 8-10 days, especially for removing nutrients; and (3) adopting

a filtratinp process using sand-gravel layers for removing PO4 -P,

In conclusion, in order to continue this study, there are still many

problems to be solved: the tolerance of aquatic plants to seawater, the differences of removal rates by different plants and in various plant densities;

the seasons carried out, the mechanism of reiovfag SS and nutrients, and the

hydrological movements of flowing'water in p( . These problems need to be

investigated in the future.

279
I / ...... .IIILWJ11 -

REFERENCES

1. W. Czerwenka, K. Seidel: Neue Wege einer Grundwasseranreicherung in Krefeld, Das Gas-und Wasserfach (Sonderdruck aus GWF), No. 106,

p. 828-833 (1965).

2. K. Seidel, G. Graue, H. Happel: Beitrige zur Gewissergesundung,

Limnologische Arbeitsgruppe Dr. K. Seidel in der Max-Planck-Gesellschaft,

p. 1-23 (1976).

3. J. D. Jong: Bulrush and Reed Ponds (Purification of sewage with the aid

of ponds with bulrushes or reeds), Int. Conf. Biol. Water Qual. Impruv.

Alternatives, March 3-5 (1976).

4. C. R. Lee, R., E. Hoeppel, P. G. Hunt, C. A. Carlson: Feasibility of the

Functional Use of Vegetation to Filter, Dewater, and Remove Contaminants

X, from Dredged Material, U. S. Army Engineer Waterways Experiment Station,

/X Dredged Material Research Program, Technical Report D-76-4 (1976).

5. D. A. Cornwell et al.: Nutrient removal by water hyacinths, Journal

WPCF, Vol. 49, p. 37-65 (1977).

6. T. Otsuki: Living Filter, Reclamation and Dredging, No. 91, p. 68-79

(1980) (in Japanese).

7. C. P. McRoy, R. J. Barsdate, M. Nebert: Phosphorus Cycling in an Eelgrass

(Zostera Marina L.) Ecosystem, Limnology & Oceanography, Vol. 17, No. 1,

p. 58-67 (1972).

I

280

>7I

•i 7 IIIIIIIIIII I II II I I II 
4AD POO2 4 0 8

THE EFFECTS OF NUTRIENT RELEASE

FROM SEDIMENTS ON THE FORMATION OF

WATER BLOOMS

Mitsumasa Okada and Ryuichi Sudo

Researcher and Head, Laboratory of Freshwater Environment

National Institute for Environmental Studies

P.O. Tsukuba-Gakuen, Ibaraki 305, Japan

ABSTRACT

.-- > Simulation of the formation of water blooms dominated by Microcystis ('jlue-green algae) was carried out

by using the mathematical m3del on the vertical migration, phosphorus uptake, and growth of the algal colonies

in a water column under the coexistence of nonsigrating

algae. Phosphorus supplies both through the inflow of

water and sediment release were considered in the model.

Numerical solutions of the nodel were in agreement qualitatively with the observati )ns reported on Nicra-cstis

behavior in eutrophic lakeý.. Phosphorus release from

sediments did not enhance the growth of Microstis nor

that of the nonmigrating algae in cases of abundant inflow of phosphorus. In :;'e absence of phosphorus inflow,

however, phosphorus relcc<.e from sediments enhanced only

the growth of Microcystis without significant stimulation

of the growth of the nonw-grating algae. Daily vertical

mixing from 1200 to 1700 in the upper layer of the water

column had little effect on the dominancy of Nicrocystis

over the nonmigrating algae.---

INTRODUCTI ON

Water blooms flourishing frequently in summer seasons in eutrophic lakes

and ponds are a nuisance to the community because they release unpleasant

odors, impair the scenic beauty, and degrade the water quality. Microscopic

examinations have revealed that specific planktonic blue-green algae, e.g.

Anabaena flos-aquae, Microcystis aeruginosa, are dominant among microorganisms

of the water bloom (1, 2).

281
Water blooms caused by plank*ýnic blue-green algae a, cumulate sometimes

during the sumner season at the surface of still waters of lakes and/or ponds

and form a thick layer. This phenomenon does not always imply an anomaly in

the algal growth, but most probably is caused by an upward migration of the

algal cells (colonies) from deeper layers of water, wherein the cells acquire

buoyancy by the regeneration of gas vacuoles.

It is well known that intracellular gas vacuoles of these blue-green

algae inflate and/or collapse depending on the cellular photosynthetic activities. Increase and/or decrease in buoyancy caused by the inflation and/or

collapse of gas vacuoles triggers the vertical travel of these algae in still

water columns. Periodic emergence and/or disappearance of the water bloom,

either diurnal, monthly, or even seasonal, as reported by field observers

could be ascribed to this particular travel of those algae (3-6). Seve-al

laboratory works and field observations on this subject have been presented

in qualitative terms by other workers. For instance, Okino and Reynolds observed independently that colonies of N. aeruginosa ascend during the period

from midnight to the early morning, forming a surface mat (or scum) of the

algae, and migrate downward in the afternoon (2, 5). It is also known that

algal colonies, once they migrate upward, stay at the water surface without

showing the diurnal migration. Factors responsible for the mat formation are

considered to be numerous and complicated; they can be extricated and identified only through simulation of the water blooms.

Despite numerous papers on eutrophication that have been presented from

various circles during the past 50 years (especially the last 10), simulative works in which characteristics of algal growth are taken appropriately

into consideration are surprisingly scarce except for a few; for instance, a

simulation of seasonal succession of algae in a eutrophic environment (7-9).

If simulation of the water blooms were successful in the sense of extrapolating laboratory and/or field observations to a certain extent, the simulation

would provide a clue of how to control and/or minimize tha water blooms.

.. In addition to the mat formation, the self-controlled vertical migration

may also play important roles in the dominaacy of the bloom-forming algae.

The vertical migration brings different environmental conditions to algal

cells, i.e., different light intensity and nutrient concentration compAred te

the nonmigrating algae. It may be possible for vertically migrating algae to

uptake sufficient nutrients and to store them inside the cells during their

stay in nutrient-rich deeper zones, and to grow rapidly under high intensity

of solar radiation when they ascend to surfa-P layers (1).

Whatever species of nutrients responsible for the water bloom, either

phosphorus, nitrogen, carbon, or other unknown materials, this ,ork presupposes

that only phosphorus limits the growth of the blu'-green algae. The various

rate equations on vertical migration, phosphorus uptake, and growth, and the

water bloom formation processes in a water column under the coexistence of the nonmigrating zIgae (denoted herefter as reference algae) were studied herein.

The role of sediment phosphorus release on the formation of the water bloom

was especially discussed.

282
MATHEMATICAL MODEL

Construction

An assemblage of Nicrocystis colonies in natural lakes is represented

in this model by 56 different sets of colonies defined by different values

of state variables at t = 0 (see later on). State variables that define

i-th (i = I ^ 56) set of colonies are X., Z., V , Pi. C., Ri. and f s.. 1 1

The growth of i-th set of colonies (denoted hereafter as' i-'th colonies)

corresponds to the increase only in the value of Xi, and R. is assumed to be

constant throughout the growth. As control variables, diurnal variation of

light intensity (sunrise = 0500, sunset = 1900, maximum light intensity at

noon = 80 klux), phosphorus loading through inflow of water and/or release

from sediments, and vertical mixing in the water column are considered.

Another assemblage of algae, the reference algae, is represented by 8 sets

of state variables defined respectively in 8 layers in the water column from

surface to bottom. Two state variables, Yk and f (k = 1 ^. 8), correspond

to the algae in each layer. Sk (k = 1^ 8) denotes phosphorus concentration

in the k-th layer of the water column.

A schematic diagram to clarify a mutual relationship among the state

and control variables concerned only with i-th colonies of Nicrocystis

(subscript i omitted) is constructed in Fig. I (outflow of colenies from the

water column is omitted), based on papers already published and field observation (3, 5, 10, 11).

The rate of change either in chlorophyll-a content, turgor pressure, cell

mass concentration, gas vacuoles, algal location underwater, or intracelluler

phosphorus concentration (dC/dt, dP/dt, dX/dt, dVf/dt, -dZ/dt, or df p/dt

shown respectively in the figure) constitutes the key to the mechanism of

water bloom behavior. Except for 1, Z, S, etc., which are all extracellular

and physical in character, most of the variables in Fig. I deal with intrdcellular and physiological activities of each colony of Nicrocystis. Arrows

in the figure indicate that a specific variable is dependent on another

variable, from which the arrow originates. For instance, Q is shown as an 0 2

explicit function of I and C, whereas Q0 is assumed to affect explicitly

the rate, dP/dt. 2

Similar to Nicrocystis, the rate of growth for the reference algae is

assumed to be an explicit function of I and f . The transport of the biomas-,

of the reference algae through boundaries of each layer, i.e. sediment3tion,

and eddy diffusicn is taken into consideration instead of the vertical migration of Microcystis colonies. Outflows of algal cells from the water column

are assumed both for Microcystis and the reference algae.

*See Notation at end of text.

283
vertic grton d t nutrients

Figure 1. Schematic diagram of state *and control variables to be

used in simulation of the water bloom (Nicrocstis)

Unit processes and their rate equations are presented in References 11-16

to account for the vertical migration of Microcystis in the water column and

rate of phosphorus uptake. The formulation on the phosphorus uptake by

Microcystis is assumed to be applied to that of reference algae. A model of

a system of differential equations to solve for and/or simulate the algal

behaviors (Nlcrocystis and the reference algae) is based on the rate equations

in Table 1.

Solution of the Model

Parameter values used in this simulation are the same as those presented

previously. It must be noted that all the values related to the physiological

state of Nicrocystis came from laboratory experiments and/or field observations on Microc~stis aseiginosa, except for some parameters on the rate equations of turgor pressure (which came from a blue-green alga, Aaaeana flosaquae).

Using the results of field observations of a Micricstis water bloom in

Lake Kasumigaura, 7 radii of colonies, 15, 25, 35, 45, 55, 65, and 75 pm were

assumed. Colonies of each radius started simultaneously from 8 different

depths taken at the same interval from the surface to the bottom of the water

column (depth = -8.0 m, 1.0-in intervals from -0.5 to -7.5 in). Thus,

284

02 R' z i Gs l ?i is I I
TABLE 1. SYSTEM EQUATIONS AND ADJUNCT EQUATIONS USED FOR

THE SIMULATION MODEL

System of differential equations (360 dimensional i = 1, 56; k = 1,8)

dXi - (-----)36 S= ui~i -Zmin (3-i)

dW i

Tmn

_Zi 2~ ' iR 2 x 3,600 (3-i)I

B• 9uw

dV f (.Vfi - Vf

itid eq,i for Vf Vf qi(4-i) St -dt Vfi Veq,i

or

for V fi < Vfeq,i

dP. dt _ a(P - Pi)Q°, (P - pm ) (5-i)

dt max i 0 2,i 1 min

dC

T t--: (Cmax - Ci) - yICi (6-i)

d'Yk D (Y k+l - Yk) (Yk-l - Yk)

dt-- p,k (_Zmin/8)2 p,k-I (-Zmin/8)2

QY k 8vsY k-i 8VsYk

mi-Z-n min mn kk (7-k)

285
TABLE 1. (Continued)

56 8

I., =10 exp(- E~ tl~j X~ Ci - £'j Y 3 + n'Z1) (12-i)

j=1 j!

amm' for Z < Z

=0 for Z i ýjZmin / 8

mllfor Z < jZ /8 Smin

56 k-i

I 1 0 exp(- z el i C.j - m"Y. + n' (k 81) zmi) j.1 ~ ~ ~ 8 m

(13-i)

elfkij ml for Z.> (k-1)Zmi/8

2 0 for Zj (k-1)Zmi/8

Q Qs ma -f ____ mx s s~max fsc

fs s~a fSmt)

I fs fs,mi x sc-ik

p + qI + riZ q + s s,min

286
TABLE I. (Continued)

dWk (Wk+1 - Wk) (Wk. - Wk)

dt -p,k (.Z min /8)2 + Dpsk-I (_Zmin/8)2

QWk 8 VsWkl 8VsWk

"Zmin + + Qs,k Y k (8-k) -'min -•mn

dSk (Sk+l - Sk) + (Sk-i - Sk)

Sp,k (_Zmi /8)T2 + p.k-1 (_ ';i /8)2

Ls QSk8 s i i

+ L. - - Qs,kYk (9-k) -kZmin ik -min "Zmin

Adjunct equations (i = 1, 56; k 1, 8)'

Q'2 = mCili for Ii < (ae +. b)/m (lO-i)

2,i

or

= (ae + b)Ci for Ii (ae + b)/m

Pi

Vf (1 f f (•,a,P)dP) (ll-i) eq,i Vfmax 0 n

287
56 different sets of colonies are presupposed to simulate behaviors of an

assemblage of Nicrocystis colonies in eutroilic water bodies.

Obviously, the system equations cannot be solved analytically. A numerical procedure by the Runge-Kutta-Gill method was employed to solve for the

equations (HITAC M-180, Computer Centre, National Institute for Environmental

Studies). About 40 simulation runs were conducted taking various combinations

of conditions shown in Table 2 to assess the effects of phosphorus release

from sediments on the growth of Microcystis. Time length for these runs was

25 days.

TABLE 2. VALUES OF PARAMETE:RS TAKEN IN SIMULATION RUNS OF A

WATER BLOOM (SENSITIVITY ANALYSIS)

Simulation to find the effect of Values .,,ed in simulation*

Yk (t 0) 1.0, 2.5, 5.0, 10.0

SL 0.0, 0.3

Psed 0.0, 5.0, 10.0, 20.0

Q 1.0, 2.0 (times of Ks value

for Microcystis)

' k 1.0, 2.0 (times of p value

for Microcystis)

V s0.0, 0.1, 0.5

mixing none, 12:00 - 17:00

* Values underlined were used throughout simulation runs except

for otherwise noted. For the control run, all of the underlined

values were used.

RESULTS AND DISCUSSION

Vertical migration and growth of Microcystis

Patterns of vertical migration of 12 colonies (taken arbitrarily from

56 colonies) in the control run (see Table 2) are shown in Figure 2. Smaller

colonies showed little oscillating behavior during growth and ascended to the

surface layers with time. Larger ones, on the other hand, migrated vertically

with a cycle of 3 days, ascending to the water surface every three days, and

descending to the deeper layers depending on the size of colonies, i.e. the

288
S• RUN 5--1

Figure 2. Oscillation of Z. as affected by the change in initial

1

conditions and colony radius; from top to bottom:

Z.(t = 0) -0.5, -2.5, -4.5, -6.5 m, from left to 1

right: R. 15, 35, 55, 75 pm 1

deeper migration was observed for the larger ones. In other runs (except the

cases of vertical mixing), similar patterns cf migration were observed.

In accordance with these migrations, each colony showed stepwise growth

(not shown here), i.e. the specific growth rate during their stay near the

water surface was more than 10 times that observed when colonies descended to

deeper layers. However, water column average concentration of the assemblage

of 56 colonies increased linearly in logarithmic scale as shown in Figure 3.

Diurnal variations in the vertical profile of Microcpstis colonies in

still waters are shown in Figure 4. When total concentration of algae, i.e.

Microcystis plus the reference algae, was low (Figure 4a), maximum concentration in the water column was observed at the middle layer (ca. -2.0 m). Although a part of the Microcystis colonies appeared in the water surface, the

amount was small. As showa in Figure 4b, typical diurnal migration of Microcystis was observed when total concentration was high, i.e. colonies accumulated at the water surface in the morning, and descended in the afternoon. In

extreme cases, almost all colonies stayed near the water surface without showing diurnal migration (not shown here). In all cases mentioned above, each

colony showed vertical migration with a cycle of 3 days. However, the vertical range of migration narrowed with the increase of total algal concentration even in the same colony radius.

289
a

•:, RUN 5-818 AVE. CSNCW.

' 0 ~10.0 2.

TIME DAT

Figure 3. Growth curve of the assemblage of Nicrocystis

(water column average concentration of colonies,

X = log (7iXi/(-Zmin)), vs. t)

Wind-driven vertical .uixing in the surface layers of the water column

frequently occurs in Lake Kasumigaura where dense water blooms of Microcstis

appear every summer. The vertical profile of Microcystis under a mixing condition (daily mixing between 1200 and 1700 was assumed using Lake Kasumigaura as an example) is shown i.n rigure 5. Vertical profile patterns similar

to those observed in Lake Kasumigaara were observed in the simulation runs, i.e. homogeneous vertical profile during mixing, upward migration of algal

colonies after that, and surface accumulation until the initiation of mixing

was simulated.

Several studies have reported on the vertical migration of Microcystis

(2, 5, 6). However, environmental conditions such as water temperature, solar

radiation, mixing in the water column, and nutrient concentrations are nct reported in detail; it is quite natural that vertical migration of single

colonies has not been reported due to the difficulty of measurement. A cycle

of 3 days was shown in this study for single colonies in spite of a daily cycle for an assemblage of colonies shown both in this study and in field

observations. Thus, model verification in a strict meaning is impossible for

this model. Howev,-r, the infeasibility of quantitative verification does

not totally invalid.ate the usefulness of this model. In a qualitative meaning,

the model behavior c',rresponded very well with the field observation, i.e.

all three patterns og vertical migration shown by this model have been observed

in natural lakes, and the specific rate of growth (ca. 0.1 - 0 2 day- ) calculated by this model for the assemblage of Microcystis colonies is quite -1

reasonable comsred to field observations of approximately 0.1 day based

on the dAta reported by Reynolds (5). The model presented here, therefore,

could open the way to understind basic characteristics of the water bloom,

although the applicability of the model to predict water bloom formation by

Microcystis in a specific water body is not confirmed.

Effects of phosphorus release from sediments

The effects of phosphorus release from sediments on the specific rate

of growth, p, are shown i- Figures 6 and 7. If phosphorus inflow from outsid2

290
t day

........... 20 21 22

i . ...........

a)

*4,2,ttt~iS~ztr t us~t~tstuht-:c I . .E..... IL..... ... : .. .:zIt.I.. ::t;

tday

o 7i I I Hj -- i I ---- ----- 1 ---------- 1 12

iJ4J4444 4. ..... . ....

Figure 4. Vertical profiles of the concentration of Microcystis

vs. t (withou, mixing). Relative concentration based

on maximum concentration in water column (Z'.

-8.0 m) for each time is shown by darkness in the figure. Higher concentration corresponds to darker print

and a band between broken lines shows the time span of

one day

a) (upper) lower total algal concentration

b) (lower) higher total algal concentration

291.
t day

21 22 23 14 25

ii!' ld ... iilil!iii .... :iiii~ ~ :iii !j l iii... .. ..-- .-.--, ... ...... -----..----- ------ ---. ...

.. . II:f . . ..........

too.... .. ......... z..: m n " :m , :. i i

Figure 5. Vertical profile of the concentration of Microcystis vs. t'(with mixing between the surface and,-4.0 m

and daily from 1200 to 1700). See the'legend of

Figure 4 except that relative concentrations here

are based on maximum concentration in the water

column at the end of a simulation run

was abundant (Figure 6), release of sediment phosphorus P did not enhance

sed

the growth of Microcystis nor that of the reference algae. Although rate constants for growth and phosphorus uptake of the reference algae were assumed to

be equal to those for Microcystis, p values of Microcystis were larger than

those of the reference algae. The difference in p values between these two

algae was more significant when Yk (t = 0) was high, i.e. high concentration

of total algae and rapid extinction of solar radiation in the water column.

Similar results were also obtained even if the rate of sedimentation v was

assumed to be zero. s

If phosphorus inflow from outside became negligible, Psed enhanced p

values of Microcystis, whereas those of the reference algae increased slightly

(Figure 7). p of Microcystis were still larger than those of the reference

algae also in these cases. It must be noted that p values were not zero even

if Psed were equal to zero. This is because intracellular phosphorus at t = 0

(assumed as 1.0% for all simulation runs) supported algal growth.

The fact that p values of the reference algae did not increase significantl.• with the increase of P implies that phosphorus released from sedi- s ed

ments is not as useful for the growth of the reference algae as for that of

292
X 104

5 0 L0&5

4 -0.04 01

.3 0.0313

2 -0.02>

-0.01

0~

0 5 10 15 20

Psed mglm21day

Figure 6. p and average available phosphorus concentration

as affected by release rates of phosphorus from

sediments Psed with abundant phosphorus inflow

from outside (2.4 X 10-2 gP/m /day). ( 0, 0 )

Microcystis aeruginosa; (6,A) reference algae;

(0,i) available phosphorus concentration.

Open symbols Yk (t = 0) = 2.5 g/m3 ; closed

Yk (t = 0) = 10.0 g/m 3

Microcystis. Thus, the reference algae cad'utilize mainly phosphorus supplied

through the inflow of water. However, it is plausible for vertically migrating

algae such as Microcystis to utilize both inflowed and released phosphorus.

It is noteworthy that Microctjstis grows well in the presence of large amounts

of algal cells compared to the reference'algae, because the difference in p

values of Microcystis between two initial values of Yk (2.5 and 10.0 g/n 3) is

smaller than those of reference algae.

Each colony responded differently to the changes in the sources of

phosphorus supply. As shown in Figure 8, the smallest radius of colonies

(15 pm) showed the largest p value, but p decreased with the increase of

colony size if phosphorus was supplied abundantly. However, if phosphorus

supply through the inflow of water stopped, p values of smaller colonies decreased; hence, the maximum p value was observed in medium-sized colonies.

Qs values changed similarly; i.e. maximum Qs values also appeared in the

293
5 005

I 3 0.03 W

2 0.02 '

-A

1 L.01 A 

0r

0 5 10 20

Psed mg/m 2 /day

Figure 71. p and average available phosphorus concentration as

affected by release rates of phosphorus from sediments

Psed without phosphorus inflow from outside.. Refer

to the legend of Figure 6 for symbols.

smallest colonies under phosphorus-rich cunditions and shifted to larger

colonies in cases where sediment was the sol- phosphorus source (not shown

in the figure). Colonies from 45 to 55 pm,and from 55 to 75 pm showed

maximum value of Qs when P ed was 10 mg P/m 2/day and 5 mg P/ 2/day,

respectively. It is plausible that larger colonies have an advantage when

competing for phosphorus uptake with smaller colonies or nonmigrating algae

if phosphorus supply through the inflow of water is decreased and the release

of phosphorus from sediments becomes the major source of phosphorus. In

other words, the characteristic of vertical migration may play an important

role in sediment phosphorus uptake and the dominancy of Microcystis.

p values were not affected significantly by the daily vertical mixing

cf the water column from 1200 to 1700. Simulation results sho:i in Figure 9

correspond to those in Figure 7 except vertical mixing considered in runs

shown in Figure 9. Although a slight increase in p values of the reference

algae when compared with nonmixing conditions was observed-as expected, the

effects of vertical mixing were negligible. Sediment phosphorus release

also only affected the growth of Microcystis if phosphorus inflow with water

became negligible.

294
x 0- 6

5

3

2

15 25 35 45 55 65 75 aveage

R pm

Figure 8. Average specific growth rates %-)r each colony of

Nicrocystis as affected by th,. 3ources 2 of phosphorus

supply: P inflow and Psed 10 mg P/m /day

W/O P inflow and Psed 20 mg P/mr2/day

W/O P inilow and P, d , 10 mg P/M2 /day

W/O P inflow and PsPd 5 mg p/m2/day

295
5

X*

2 -

A •A

0 5 10 20

Psod mg/m2lIday

Figure 9. p as affected by Psed when the water column is sixie

vertikally from 1200 to 1700 (0 - -4 a) and phosph ,rus

is not supplied from outside. Refer to the legend of

Figure 6 for symbols

19b
CONCLUSION

Numerical solutions obtained from the model presented herein were in

agreement qualitatively with the observations reported on Iicrocystis behavior in eutrophic lakes.

According to the model, phosphorus release from sediments enhanced the

growth of Nicrocystis without significant stimulation of nonmigrating algae

if sediment phosphorus was the major source of phosphorus supply into water

bodies. Daily vertical mixing from 1200 to 1700 had little effect on the

dominancy of Xicrocyoutis over nonmigrating algae.

NOTATION

a,a',b empirical constants I -

C= chlorophyll-a content in algal cells % • I

C m max maximum value of C % •

D = eddy diffusion constant f 2 /h p

f n normal distribution of gas vacuoles with n respect to turgor pressure, [ -

f = intracellular phosphorus concentration ( g/g 5

f critical value of f between starved and SC nonstarved conditions [ g/g ]

f = maximum value of f 3 g/g I s •max S

g acceleration dut to gravity M r/s 2

I= light inteitsity underwater [ klx

I = light intensity outdoors [ klx

Ks ,K q,Kqs = empirical constants I -

L = phosphorus loadings from outside and 2

sediments X g/(m h)

m'm',m" = empirical constants -

no = empirical constant [

P = turgor pressure of cells [ kN/m 2

P = maximum value of P kN/m 2

297
Pi = minimum value of P [ 2

Psed = release rate of phosphorus from sediment [ g/(m2 h) ]

P = empirical constant I-]

Q = hydraulic loading *3/(m2. 3 h)

QO = photosynthetic activity of cells cm 3/(g h)'

2

Qs = specific rate of phosphorus uptake g/(nde h)

Qse = specific rate of phosphorus uptake under

phosphorus-rich conditions [ g/(g • h)

Qss = specific rate of phosphorus uptake under

phosphorus-starved conditions g/(8 h)

q = empirical constant [ -

R = radius of algal colonies POl

3 S = availale phosphorus concentration o/

9L= available phosphorus concentration of 3

inflowi&3 water [ g/m ]

r= empirical constant [-

t =time [hi

v = sedimentation rate constant [im/hi

Vf = volume fraction of gas vacuoles in colonies % • I

Vf : Vf in equilibrium vith turgor pressure % • ]

eq

Vf = maximum value of Vf [%]

Sax

W = algal phosphorus concentration g/mi 3

X = mass concentration of colonies g/m2 2

Y = mass concentration of reference algae giS 3 ]

Z = algal location underwater, using the levet

of water surface, as zero M I

Zmin = minimum value of Z, depth r m

298
a,a',Oy = empirical constants f - I

E,•IZ" = extinction coefficients [ -

= water temperature ( 0 CJ

A= empirical constant [ -

-l

p = specific growth rate Ih

Pw = viscosity of water f kg/(m s)

= mean value of P for f n kN/m2 n

PC = density of algal colonies with nonvacuolated 3 cells I kg/mi

Pw = density of water [ kg/m 3

a = standard deviation for f n kNI/m2 ] n

Subscripts

i,j = set of colonies

k = layer in the water column

Superscripts

- other sets of colonies j (j = I - 56, j • i) than a set of

colonies i under consideration

299
REFERENCES

1. Fogg, G. E., "Algal Cultures and Phytoplankton Ecology." 2nd Ed., University of Wisconsin Press, Madison, Wis., 79(1975).

2. Okio, T., "Studies on the Blooming of Microcystis aeruginosa." Japanese J.

of Botany, 20(6), 381(1973).

3. Walsby, A. E., "Structure and Function of Gas Vacuoles." Bacteriol. Rev.,

36(l), 1(1972).

4. Walsby, A. E., and Klemer, A. R., "The Rele of Gas Vacuoles in the Microstratification of a Population of Oscillatoria agardhii var. isothrix in

Deming Lake, Minnesota." Arch. Hydrobiol., 74(3), 375 (1974).

5. Reynolds, C. S., "Growth and Buoyancy of Nicrocystis aoruginosa Kiitz.

emend. Elenkin in a Shallow Eutrophic Lake." Proc. Roy. Soc. Lond. B.,

184, 29(1973).

6. Reynolds, C. S., and Rogers, D. A., "Seasonal Variations in the Vertical

Distribution and Buoyancy of Microcystis aeruginosza Katz. emend. Elenkin

in Rostherne Mere, England." Hydrobiologia, 48(1), 17(1976).

7. "Modeling the Eutrophication Process." E. J. MY.'ilebrooks, D. H. Falkenborg

and T. E. Maloney (Eds.), In "Proceedings of a Workshop held at Utah State

Univ., Logan, Utah." Utah Water Research Lab., College of Eng., Utah State

Univ., Logan, Utah. (1973).

8. Scavia, D., "An Ecological Model of Lake Ontario." Ecol. Modelling, 8,

49(1980).

9. Bierman, V. J. Jr., "Mathematical Model of the Selective Enhancement of

Blue-Green Algae by Nutrient Enrichment." In "Modeling Biochemical Processes in Aquatic Ecosystems." R. P. Canale (Ed.), Ann Arbor Science Pub.,

Ann Arbor, Mich,.. 1(1976).

10. Lehman, H., and Jost, M., "Kinetics of the Assembly of Gas Vacuoles in the

Blue-Green Alga Microcystis aeruginosa KUtz. emend. Elenkin." Arch. Mikrobiol., 79. 59(1971).

11. Okada, M., Sudo, R., and Aiba, S., "Phosphorus Uptake and Growth of BlueGreen Alga, Microcystis aeruginosa." Biotech. Bioeng., 2_.4, 143(1982).

12. Aiba, S., Okada, M., Sudo, R., Ogawa, T., and Sekine, T., "Simulation of

Water-bloom in a Eutrophic Lake 1. Photosynthetic Characteristic3 of Microcystis aeruginosa." Water Res. (1983) (In press).

13. Okada, M., and Aiba, S., "Simulation of Water-bloom in a Eutrophic Lake II.

Reassessmentof Buoyancy, Gas Vacuole and Turgor Pressure of Nicrocystis

aoruginosa." Water Res. (1983) (In press).

14. Okada., M., and Aiba, S., "Siulation of Water-bloom in a Eutrophic

Lake III. Modeling the Vertical Migration and Growth of Nicrocystis

aoruginosa." Water Res. (1987)) (in press).

15. Okada, M., Sudo, R., and Aiba, S., "Simulation on Emergence and/or Disappearance of Waterbloom in a Eutrophic Lake." Research Report from the National Institute for Environmental Studies, (in Japanese), (25), 83(1981).

300
_II

16. Okada, 

appearance 

M., Aiba, S., and Sudo, R., "Simulation on Emergence and/or Dis- of Waterbloon of Nicrocystis aeruginosa Verh. in a Eutrophic Lake." Internat. Verein. Liinnol., 21, 1421(1981).

301
AD P 002409

SUMIMER PEAK OF NUTRIENT CONCENTRATIONS IN LAKE WATER

T. Yoshida

Japan Bottom Sediment Management Association

Tokyo, Japan

Abstract

-4--•The nutrient concentrations of lake water are strongly influenced by

both inflowing nutrients and those released from sediment in the lake. The

former may be related to the basic nutrient concentration of the lake in winter

and the latter to the peak concentration in summer. This paper considers the

problem of how the summer peak may be generated, using actual data from two

lakes in Japan. By using a mathematical simulation, it can be shown that the

sumer peak way be generated largely from nutrient materials released from

sediment. Using this approach, release rates have been calculated for two

lakes. The approach makes a prediction of water improvement due to sediment

removal.--

Background

The lakes used in this paper are Lakes Suwa and Koyamaike.

o 1 2 3 4 5km

Lake Suwa Lake Ko)'Uike

Lake Suwa is situated in the mountain district near the Nippon Alps and has a

lake area of 13.7 x 106 a2 and a mean depth of 4 a. Three big cities, Suwa,

Okays, and Chino, are located around it with a population of about 170,000

people. There are a number of manufacturing industries in the area.

302
The Suwa district is also the most famous hot spring site in Japan, and

the sightseeing population amounts to about 600,000 people in a year. These

special conditions increase the seriousness of eutrophication.

Lake Koyamaike is situated in the western district facing the Nippon

Sea, and, in contrast, has the lowest population density in Japan. Although

no factories and no big cities are located around it, the lake is polluted.

This is probably due to the effects of agricultural and rural drainage. The

lake has an area of 6.94 x 106 m2 and a mean depth of 3 m.

Sumer Peak of Nutrient Concentrations

The 1973 seasonal variation of total phosphorus (T-P) concentrations in

Lake Suwa, offshore of Kamikawa, is plotted in Figure 1.

600-

0

400

0.

0

~-200-

U

0

U

0

00

0C I I I I I I I

J FM AM J J A SON D

oeason

Figure 1.. Seasonal variaticrh of T-P concentrations in Lake Suwa (1973)

303
The measurements were made at 10 points on the lake. The location off

Kamikawa was the highest concentration.

It is apparent that an exceptionally high phosphorus concentration was

generated in summer. During the remainder of the year, the concentrations of

T-P are below 100 p3/1, although a small peak of about 150 pg/i is seen in

spring. From the end of June, they increase Lapidly and reach a maximum value

of about 550 pg/i in summer.

The seasonal change in T-P concentrations in Lake Koyamaike is shown in

Figure 2. In this a summer peak is also seen. The concentrations of T-P during the nonstamer period are about 50 pg/i, but in sumer they increase to a

peak of about 400 pg/i.

-t~tom .t . •+ upper layer

loyer

0. ,

c 200-

0

S100

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

Seison

Figure 2. Seasonal variation of T-P concentrations

in Lake Koyamaike (1978)

From these data it is clear that a summer T-P peak is generated in both

lakes, resulting in highly eutrophic conditions. The cause of this problem is

investigated herein using a model approach.

Model Approach on Summer Peak

Regarding summer peaks, we approach a lake model as follows. If we

304
assume that the quantities of inflowing pollutants to a model lake are

constant, we have to take into account only the effects of the released materials from bottom sediments. The variation of nutrient concentrations in lake

water may be releated to them and can be represented as follows.

H

g PrA= R

/////////////////777///1

V ArA - cQ

Here:

V = water volume of lake m3

Q = quantities of inflowing water m 3/d

2

A = lake area m

R = released quantities mg/d

c = mean concentration of nutrients mg/mr3

in lake water (Pg/P)

Pr = release rate of T-P mg/m2 /d

Eq. (1) is rewritten as follows

ac •VA Pr

T- + 2c = Pr H (2)

Here H denotes the water depth of the lake.

The solution of Eq. (2) becomes

vtt

ce = J - e dt + C (3)

305
Since p is a function of time, it is necessary to solve it for the integration ofrthe right side of Eq. (3).

The seasonal change in water temperatures is shown in Figure 3.

*C

26

24

22

20

1972-1973

16

6 0

S0 k 4

0

102 

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

Season

Figure 3. Seasonal chang.? of water temperature

in Lake Puwa

As the figure shows, the seasonal curve of water temperature is very regular

and can be simulated as a parabolic curve (Figure 4).

Here we assume the following equation for the variation in water temperature.

T=T t 2 (4

T max 2p t-()

where:

T ='water temperature at lake bottom

t =time

306
Pt = figure index of parabolic curve

2

2(Tmax - Tmin)

T

T

Tmax

i t

Figure 4.' Parabolic curve

The relationships between release rates and water temperature have been based

on our test results, shown in Figure 5.

From these, the following equation can be proposed

Pr(t) p r(20OC)aT-20

a =I. II (5)

Hence we obtain

T -20- --

Pr(t) p r(200 C)a max 2pt

Next we must consider the effects of DO on release rptc..

The measured DO concentrations at lake bottom are shown in Figure 6.

1/ 307
-L IJ IM r'VPMI --

26

24

22 " DO=0- 1 ,9l/1

20 Sediment Thickness 30 cm

0

U) 12

M 10

U)

S 6

4)

2

0 1 I I * *

2 4 8 81 0 12 14 16 18 20 22 24 26 2 8 C

Water Temperature

Figure 5. Relationships between release raLes of T-P

and water temperature, Lake Suwa

Figure 6 shows that the DO concentrations at lake bottom change greatly,

according to the season. They arz high in winter, but decrease rapidly during

the transfer from spring to suimer. They reach a minimum value of 1 mg/2 in

July. After that, they increase to regain the winter value. Because it is

very difficult to simulate this by a curve, we have used an empirical

approach.

Then Eq. (3) becomes as follows:

St T -20 - t

2 t ce V pr(200 C)c max . t + cr e dtHC (7)

308
• ..

13

12

11

010

g 90

8.

04 7

J F M A M JJASO0 N D

Seas) n

Figure 6. Seasonal change of DO at lake bottom,

Lake Suwa

Here we put,

t2

TV-$ t

F(t)f• e dt

This function is represented in series as follows.

2V2

1 9' t2 +.518\ I(9 q- t' 2.528 

tPt2 Pt 3

3 2P~ 3 . ' 0020

ý6113 Pt )4- X v 4 p 2t V2 ÷ Pt

Pt-

(a 1.21)

309
Finally we obtain the mean concentration of nutrients in lake water

caused by release of sediment materials, as follows:

Pr(2000) T -x20 "Vt -Vt

C = r H max F(t)e + Ce (8)

Since the boundary condition is t = 0; C = C0, and F(M) = 0,

we get C = C Hence Eq. (8) becomes,

pr(200C) T x20 Vt

C=rH amx FteV +C0eV 2 t (9) = r a F(t)e e(9

v

The release rates (p r ) involve the effects of DO, and F(t)e is a

function of water temperature and Q/V . Therefore, we can say that the

summer peak is caused by three factors: DO, water temperature, and Q/V

Numerical Calculations

Lake SuwaOn the basis of measured values of the summer peak at the center of the

lake, the release • rates (p . r ) may be obtained by calculation. Here we assume

that the basic concentration of T-P in winter is 80 pg/I (Figure 7). This is

also presumed to be similar to the concentration of inflowing pollutants. The

variation of water temperature used for the calculation is shown in Figure 8.

Table I indicates the calculated values of pr ' which are graphed in Figure 9.

C = 480 - 80 = 400 PR/I max

C0 = 460 - 80 = 380 Pg/j

T = 230C max

T , = 40 C (t = 135 days) min

t= ( t 2 135 -T 22 = 480 day 2 /0C

2(Tmax - T)min 2(23 -

Q = 15 m3 /S = 1,296,000 m3 /d

V = 63.65 x 106 m3 Q/V = 0.02 day

Tmax -20 23-2-

a = l.1 1.368 H = 2.6 m

310
9/May 110 LO9/t

101 13/June 90

4/July 290

i/Aug. 46G

5/Sep. 425

3/Oct. 303

18/Oct. 7 u

8/Nov. 117

6/Dec. 62

0 300 0

T-P

200

00

* I I 0 ,

M J J A S ON

Figure 7. Peak concentrations of T-P in Suwa (1973)

TAN.- I .wi,(-Calculat t of P

i

2 t - 2 , t Tit) M Co 6C C p 10 r

day vq/t Wq/f *q/It mq/w /21

-ho -420,3 3.32 1261.6 -1432.9pr 0 1.14

-30 -57.A4 1,A2 . 4• ,i. b -S5. 4pr 140 9.213

0 0 1 )No 0 3e80 (17.4)

16.l,4 ) 0.741 261.6 6.p 4003 114,

3)0 31.88 0,549 204. b 9.pr 0 1. )7

6,0 194,.4A ). O 114,4 31.3pt 220 3,4o

L j 178A.2 0.165 62.7 I55.2pt 70 o.V5

120 R901 0. O 1 )4.5 A 4 2b,.2p t 0 - .N

W~ 30102 0. 050 114.0 741.1p

T - 20 2t 2t

C p-r Fil(#)V C - AC CO v

311
151

20

15

0

M J J A S 0 N D

• -3 0

0

0 "

o

I I 0 I L,

M J J A S O N D

Figure 8. Data for calculation, Lake Suwa

312
Since the function F(t) is 0 at t = 0; the release rates (p r at this point

cannot be obtained by calculation. So it has to be estimated from the continuity of the 2curve. The labozatory test results for sediment samples were

P = 15.8 mg/m /d in an anaerobic condition (Figure 9). On this basis the

calculated valuen appear to be comparable to those of the test results.

Lake Koyamaike

The seasonal variation of water temperature and the summer peak of T-P

in Lake Koyamaike are shown in Figure 10. It is apparent that the maximum

point is much delayed from that of water temperature in Lake Suwa. Here we

assume that the basic concentration of T-P in winter is 50 jg/2.

Cmax = 400 -50 =350 pg/1 (t 54 days)

C = 80 -50 =30 pg/'

T = 31 OC max

T in = 5 oC (t = 150 days)

t2 150 2

= 5 = 433 day 2/OC

Pt 2(Tmax - T min) 2(31 - 5)

Q 4.6 m3/sec = 397,440 m3/d

V = 18.5 x 106 m3

37- = 0.02 day-l

V 18,500,000

The back-calculation of p is summarized in Table 2, and the calculated

values of pr are graphed in Figure 11. The release rates of total nitrogen

are also computed by the sate method; the results are indicated in Table 3 and

Figure 12.

313
20

is

1. . Release Tests

14

2

10

6 W

4'

2

M J J A S O0N

Figure 9. Calculated release rates, Lake Suwa

314
0C

p10 .

M A M J J A S O N D

500

400

300

200

100

. 0 _ _ _ _ _ _ _ _ ,

M A M J J A S O N D

Figure 10. Data for calculation, Lake Koyamaike (1978)

315
TabLe-i Back-calculation of p

- t d•

7(tM e Coe vC pr 0 r 2L

day wg/I _g/t wg/I mg/m /d

-60 -905.4 3.32 99.6 -3509.3p 10 0.03 r

-30 -61.15 1.82 54.6 -1299pr 10 0.3

0 0 1 30 0 30 (5.5)

30 30.88 0.549 16.5 19.79pr 250 11.8

54 123.17 0.340 10.2 48.89pr 350 6.95

60 205.36 0.301 9.0 72.16pr 330 4.45

90 1956.7 0.165 5.0 37 6 . 9

pr 200 0.5

120 9824.4 0.091 2.7 1043. 7

p 75 0.07 r

150 33315 0.050 1.5 19446pr 0 0

p (20 QC) T -20 t _.L t

ac r H -m F(t)e C AC + Coe

mg/m2 /d

12

10

8

Pr 6

4

M J J A S O N D

Figure 11. Calculated release rates of T-P,

Lake Koyamaike (1978)

316
Table-3 Back-calculation of n r

- t -•t t F (t) e Co li AC C n

day ug/i g/1 wg/I mg/m2 /d

-60 -905.4 3.32 1328 -3509.3n 20 0.4 r

-30 -61.15 1.82 728 -1299n 160 4.4 r

0 0 1 400 0 400 (37.0)

30 30.88 0.549 219.6 19.79n 1570 68.2 r

54 123.17 0.339 135.6 48.89n 1900 36.1 r

60 205.36 0.301 120.4 72.16n 1910 24.8 r

90 1956.7 0.165 66.0 376.9n 134 0.2 r

120 9824.4 0.091 36.4 1043.7n 72 0.03 r

150 33315 0.050 20.0 19446n 0 0

n (20 0

C) T - 20 - - Q t

r H m3x F(t)e V 6C= C + C e

mg/rn 2/d

70

60

50

n 40

r)

300-

M J J A S O N D

Figure 12. Calculated release rates of T-N

317
Considerations of Lake Restoration

As mentioned before, the nutrient concentrations of lake water are composed of the following two components: (1) basic concentration in winter, and

(2) peak concentration in summer.

-.4 A..

COU z

U 0 basic conc.

Season

In these ra.es, the mean annual concentration of nutrients has no meaning.

The low concentrations are related to inflowing nutrients and, by using a mathew3tical simulation, the summer peak can be related to nutrient materials

released from sediment. It is unlikely that nutrient release from sediments

occurs in winte-r.

Based on these suppositions, it seems possible to restore the lakes by

removing the summer peak. The best way may be to remove sediment, that is, to

cut off internal loading. However, a gradual buildup of nutrient levels in

newly exposed sediments may require repeated sediment removal at some future

date if nutrient input loadings remain at high levels.

z

* before dredging 0

0

S' after dredging

0-

U

season

As to the release rates after dredging, we can obtain them by release

tests in the laboratory, or by calculating their theoretical values (Yoshida,

1980). Since the presumed values of release rates after sediment removal are

known, we can predict a restored water quality.

318

/
Conclusions

A mathematical simulation of the summer peak of nutrient concentrations,

generated by materials released from the sediment, has been given. From these

studies, it seems that internal loading from released materials may have a

great influence on lake pollution.

There are many lake restoration projects in Japan based on sediment removal, and, under the conditions of our studies, these seem to be an effective

and immediate way to reduce the summer peak. The long-term effectiveness of

such treatment, however, has not been considered in this presentation.

Reference

T. Yoshida, Mathematical Model of Phosphorus Release from Lake Sediment,

XXIst Congress of International Association of Theoretical and Applied

Limnology, August 1980.

319
, . . -. •. " * .

-P 0 0~ 24

1981 STATUS REPORT ON THE ENVIRONMENTAL AND WATER

QUALITY OPERATIONAL STUDIES PROGRAM

J. L. Mahloch, K. G. Hall

Environmental Laboratory

U. S. Army Engineer Waterways Experiment Station

P.O. Box 631, Vicksburg, MS 39180

ABSTRACT

Qu-aIn October 1977, the Environmental and Water

Qua~ity Operational Studies (EWQOS) was initiated under

the sponsorship of the Office, Chief of Engineers (OCE).

The EWQOS was planned as a 6-year program of applied

research to answer select, high-priority environmental

quality problems associated with the Civil Works

activity of the Corps of Engineers (CE). Rapid development of technology and changing priorities of research have expanded both the scope and the planned

duration of the program to 8 years and a scheduled

completion in fiscal year 1985. The program is

managed for OCE by the Waterways Experiment Station

(WES), Vicksburg, Mississippi. This paper will present the program in its present form and provide the

status oL the research to date.-

INTRODUCTION

The EWQOS Program roots can be traced to a survey of the CE field offices during 1976. The purpose of the survey was to identify and assess the

magnitude of environmental quality (EQ) problems facing the Corps and to determine the major areas of common problems that could be addressed by a comprehensive research program to the benefit of the Corps as a whole.

Meetings were held at each of the CE Continental United States (CONUS)

Division offices with representatives of planning, engineering, and

construction/operations elements from the Districts and Divisions particiLating. Representatives from OCE also attended. These meetings were used nD.

only as a forum to present environmental problems, but the Division offices

also were asked to provide detailed information on specific problems, their

frequency and effects, and the CE projects associated with them.

320
At the conclusion of the survey, the problem- were compiled and analyzed at the WES and published in Technical Report E-77-1, "Reservoir and

Waterways - Identification and Assessment of Environmental Quality Problems."

Contained in the report was the research proposal that was later identified

as the EWQOS Program. Formal approval for EWQOS was obtained in the spring

of 1977 and an intensive effort was initiated to finalize research plans and

select data collection and technique development and demonstration sites.

One of the early recommendations was that the program contain an extensive

effort of long-term comprehensive field studies both at Corps reservoirs and

select waterway project sites. Ahe long-term field sites were felt essential to the program both as a comprehensive source of data and as demonstration sites for the operational/management techniques developed within the

program.

To ensure the research remained re.ponsive to the Corps' needs, a Field

Review Group (FRG) was formed to monitor progress, assist in technology

transfer, and make recommendations on the scope and direction of the program.

The FRG is composed of representatives of the 10 CE CONUS Divisions and

meets twice yearly to review progress and provide inpc2 to the following

year's research plans. The Technical Monitors (TM), of which EWQOS has three,

represent the Planning, Engineering, and Construction/Operations Divisions of

OCE. They are responsible for program review and approval as it relates to

OCE policy. The intent of this elaborate review system is to ensure the responsiveness of the program to the changing needs of the Corps.

EWQOS ORGANIZATION

Since it was not feasible to address all the environmental problems

identified in the original survey, considerable time was devoted to organizing those that could be addressed into an efficiently operating, comprehensive program. The problems fell logically into six general categories which

represent a grouping of work that meets a major program objective. These

groupings, or projects as they have been named, were divided into work units

and the work units further subdivided into tasks. The table attached gives

the current breakdown to the task level and the status as of the end of

FY 81. The reservoir and waterways long-term field study efforts, identified

earlier as essential to the program, have been segregated into individual

projects. They are designed to meet multiple objectives over the duration

of the EWQOS Program. Their principal goal is to provide information that

can be used in other projects to meet specific objectives. Other field

studies were planned and are being conducted under specific tasks, but are

generally of short duration and require only small amounts of the program

resources.

The objective of EWQOS is to provide the CE with the new technology required to meet the national environmental and water quality objectives while

fulfilling the assigned mission of water resources development and management.

Inherent with this objective is that the technology developed will be provided in the form of usable end-products to the appropriate functional

321
element within the Civil Works area of the CE. In essence, the t(chnology

transfer aspect of the EWQOS Program is essential to the successful completion of the program.

The current research area , their status, and the inticipated benefits

are presented in the project f imework used to organize EWQOS.

PROJECT I

PREDICTIVE TECHNIQUE" TO DETERMINE ENVIRONMENTAL EFFECTS

Research efforts within Pro. 'ct I involve work on lnderstanding the

physical, chemical, and biological processes that are taking place in the

reservoir and waterway environments, and, having improved our understanding,

develop predictive models that will better describe the 'impacts of project

alternatives on the environment. Methods for determining annual loadings to

reservoirs and the development of simplified techniques :for predicting environmental effects of reservoirs are also being researched through the compilation and analysis of a massive data set.

Progress to Date

Accomplishments related to the physical processes of reservoir hydrodynamics include research designed to describe reservoir! inflow and internal

mixing processes, physical modeling of reservoirs, effects of scale distortion in physical models, evaluation of two-dimensional hydrodynamic models,

studies on the hydrodynamics of pumpback hydropower operation, and sediment

transport in reservoirs. Results of studies on inflow and internal mixing

have been incorporated into existing models improving their capability to

accurately simulate reservoirs. Work related to inflow mixing and physical

modeling has been completed. Methods to evaluate pumpback mixing processes

on reservoir hydrodynamics are being developed.

Evaluation of two-dimensional models has resulted in selection of one

model for improvement. Thir model will serve as a base for including reservoir chemical and biological processes and other water qiality algorithms.

Revised procedures for simulating key biological processes in reservoirs,

including benthoL, phytoplankton, zooplankton, and fisheries, have been developed and incorporated in appropriate one-dimensional models. Guidance on'

the use of these techniques including data requirements, ýsampling procedures,

and interpretation of model output have been prepared for CE field offices.

The improvements to models for simulating both aerobic and anaerobic processes in reservoirs are under way utilizing both laboratory and field

studies. Guidance has been developed on the use of remote sensing for determining the nature and extent of reservoir ice cover, and methods have

been developed for modeling the thermal exchange between reservoir sediment

and overlying water.

CE-QUAL-RI, a one-dimensional reservoir water quality and ecological

model, with many of the new algorithms installed, is presently undergoing

verification, and a user's manual Is available. Existing riverine water

quality models have been evaluated with respect to applicability to CE needs.

322
Guidance has been prepared on available techniques for predicting loadings

to reservoirs w.th emphasis on study requirements, objectives, and comparative evaluation of current techniques. A data base of reservoir water

quality and associated project data has been compiled for over 300 projects.

Initial evaluation of the properties of these data has yielded information

on existing data variances that will be applicable to improving sampling and

monitoring programs.

Benefits

Predictive techniques are required during all project phases to determine potential environmental effects on reservoir or riverine environments.

During the preliminary planning phase, predictive techniques can be employed

to determine whether projects will meet established environmental quality

objectives, and to assist in defining the range of alternatives for further

consideration. The resultant savings would be time and money needed to

study unacceptable alternatives and will increase the range of alternatives

that may be explored. During engineering, predictive techniques are useful

in determining the environmental effects of various designs and will provide

the necessary information to aid in design decisions. For operational

projects, predictive techniques are essential in evaluating new operational

procedures to meet environmental quality objectives and will result in monetary savings by eliminating or reducing postproject modifications that are

not cost-effective in meeting environmental qiality objectives. Generally,

predictive techniques produced from Project I will save time required for

environmental studies and result in more defensible studies--thus reducing

the time required for project completion. Project I will not produce a

single procedure, but rather a number of procedures that, depending on the

situaLion, will reduce the time and data required for making an environmental

evaluation. For example, in certain operational situations or in the early

planning stage of a project, a substantial savings can be realized by employing one of the simplified techniques rather than a more elaborate and costly

analytical technique.

PROJECT II

RESERVOIR OPERATIONAL AND MANAGEMENT TECHNIQUES

TO MEET ENVIRONMENTAL OBJECTIVES

Many of the environmental problems facing the Corps may be influenced

to a greater or lesser degree by the operational and management techniques

used at the project. Nuisance algal blooms, reservoir release problems,

contaminants, reservoir regulation, effects of fluctuating reservoir pool

levels, and the importance of preimpoundment site preparation are being investigated within Project 11.

Progress to Date

Accomplishments in Project 1I include an evaluation of control methods

for nuisance algae (including state programs) and a natioial workshop to

select the most promising techniques requiring additional development.

Guidance on the significance of internal nutrient cycling by aquatic plants

j23
to reservoir eutrophication was published. Field studies to develop release

criteria for both flood control and hydropower projects were performed and

the effort coordinated with the U. S. Fish and Wildlife Service. A problemoriented bibliography and literature review for reservoir releases were

published and distributed to field offices along with guidance on their use.

Field studies of the use of vegetation to control impacts of fluctnating

reservoir pool elevations are continuing. Initial guidance on selection of

flood-tolerant plant species (EP 1110-1-3) to ameliorate problems associated

with fluctuating reservoir pool elevations has been published, and updates

have been prepared based on results of the field studies. A national workshop on fluctuating reservoir pool elevations and their associated problems

was held emphasizing case studies and solutions. A survey of the nature and

extent of contaminant problems at CE reservoir projects has been completed

and includes information on the fate and effect of major contaminants in CE

reservoirs plus initial management strategies to solve these problems. Work

on single reservoir regulation procedures is continuing and a specific application has been made. A user manual for a basin-wide regulation model is

available and work is continuing on expanding this technique to include different operational scenarios as well as multiple water quality parameters.

Laboratory studies have been used to successfully simulate water quality impacts of reservoir sediments and can be used to assess the effectiveness of

alternative site preparation plans. A report on. site preparation factors

that affect fishing quality in reservoirs was published.

Benefits

A majority of the benefits derived from the results of Project II will

be applicable, in general, to operational projects and will result in a

reduction of lost project benefits caused by environmental quality problems.

The results of Project II will document the costs and benefits of any technology, thus forming the basis for rational decisionmaking and establishing

trade-offs between water use and environmental quality objectives. Benefits

from work on nuisance algal control will include reduced aesthetic problems

(increased recreational value) and associated water quality problems results

from eutrophication. Initial results have been used by St. Paul, Savannah,

and Albuquerque Districts. Results from the reservoir release studies will

provide a sound basis (or criteria) for establishing reservoir releases and

allow the documentation of their benefits, arnd reallocation of water for

other purposes (i.e., impact on water conservAtion). Application has been

made to Lake. Hartwell (South Atlantic Division). Results from work concerning major reservoir contaminants will provide guidance on the fate and effects of these constituents in reservoirs, thereby reducing delays associated

with questions concerning these contaminants on new projects and providing

methods to reduce losset due to contaminant effects on water supply, recreation, and fisheries. Benefits from improved reservoir regulation techniques

will provide better management for water quality objectives avoiding poor

(and costly)'management procedures or project modifications. Techniques have

been applied at Cowanesque Reservoir (Baltimore District) to solve a fishery

problem downstream from the project. This technique maximizes the capdbility

of selective withdrawal systems avoiding increased design or construction

costs. Results from work on fluctuating reservoir pool elevations will

324
provide h :dance to reduce the impact on aesthetics, recreation, and water

quality. Since this problem is known to affect more than 100 operational

projects, potential benefits will be significAnt. Field studies ongoing at

Lake Wallula (Walla Walla District), Lake Oahe (Omaha District), Lake Texoma

(Tulsa District), and DeGray Lake (Vicksburg District) will produce results

directly applicable to reservoirs in these respective regions. Application

of results to Walter F. George and George W. Andrews reservoirs (Savannah

District) is anticipated to result in a substantial cost savings over other

methods of erosion control and, due to prevention of loss, project benefits.

Work related to reservoir site preparation will provide guidance to Division

and District offices to minimize subsequent water quality problems, standardize clearing practices for a variety of project purposes, and reduce the

requirement for unnecessary site preparation. Work on reservoir site preparation has been performed or is ongoing at B. EveretL Jordan (Wilmington District), Bloomington (Baltimore District), Richard B. Russell (Savannah District), and Beech Fork and East Lynn (Huntington District).

PROJECT III

ENGINEERING TECHNIQUES FOR MEETING RESERVOIR

WATER QUALITY OBJECTIVES

The engineering design of the outlet works stilling basins and associated structures has great potential for improving release water. Other engineering techniques within the reservoirs are also showing great progress for,

water quality iuproverkents., Work in Project III was designed to examine

these engineering techniques.

Progress to Date

Accomplishments in this project include the field evaluation of reaeration for nonhydropower projects, work to determine the reaeration potential

of structural modifications, and improvement in the capability to describe

selective withdrawal under varying designs, plus updated design guidance and

input to a revised outlet works manual (EM 1110-2-1602). Work related to

improvement of in-reservoir water quality involved evaluation of mixing/

destratification techniques and seraticn techniques. Initial guidance on

reservoir destratification has been published. An engineering technical

letter on calibration of the D'Aoust saturometer was produced and reports on

modeling reaeration in hydraulic structures, use of tracers to measure reaeration, design guidance on reaeration through gated-conduit outlet works, and

associated field studies were published. Field studies on reservoir aeration

and possible nitrogen supersaturation were completed along with a literature

review on the environmental effects of reservoir destratification/aeration.

Benefits

Engineering solutions to reservoir environmental quality problems by

the modification of projects or improvement in design represent a significant improvement to technology. Thorough knowledge of the costs, both

capital &nd operating, will allow evaluation of this engineering technology.

Coupled with the benefits, which can be quantified through other results of

325
the program, this will permit a careful evaluation of project designs and

modifications thus improving the design efficiency and effectiveness while

providing a solution to reservoir water quality p1tllems. Studies to assess

the selective withdrawal capability of outlet structures have been applied

to Sutton Dam (Huntington District), Lake Sidney Lanier (Mobile District),

Dickey-Lincoln Dam (New England Division), Clark Hill (Savannah District),

and Lost Creek (Portland District). Results have also been applied to Harry

S. Truman (Kansas City District), Richard B. Russell (Savannah District),

Tablerock (Norfolk District), and Littlerock, Carlyle, and Shelbyville (St.

Louis District). Improvements to the D'Aoust saturometer have been used to

evaluate nitrogen supersaturation problems at significant cost savings over

previously used procedures. Results from reaeration studies have been employed to evaluate low-head hydropower impacts on the Illinois waterway

(Rock Island District) and lock and dam structures in the Red River (New

Orleans District) and Coosa River (Mobile District) projects.

PROJECT IV

ENVIRONMENTAL ASSESSMENT TECHNIQUES FOR PROJECT

PLANNING AND OPERATIONAL REQUIREMENTS

Work within Project IV includes improvement of environmental assessment

techniques, evaluation of environmental data management systems, and use

of biological indices or indicators for assesbment.

Progress to Date

Prior accomplishments in Project IV include review documents for

critical variables in the four accounts under Principles and Standards,

environmental assessment methodologies (including publication of EC 1105-2-

102),,legal aspects of quantitative approaches to environmental assessment,

environmental data management systems, and biological indicators and indices

for riverine systems. Guidance summarizing available biological indices and

their use is available. An Evaluation and Analysis Sensitivity Program (ESAP)

was developed for application to EQ planning, and a user manual is available.

Project IV will be concluded with the completion of EQ planning and

evaluation techniques during FY 82.

Benefits

Establishment of regulations related to EQ planning resulted in many

questions as to how these regulations may be implemented with the myriad of

available techniques. Project IV will produce recommended techniques applicable to these regulations that have been field tested and will produce time

and cost savings in environmental planning; will produce more defensible

environmental assessments; and will prevent project delays and costly litigation. The results of work on environmental assessment are being used in

the Whitewater River Basin study and Central Arizona Water Control study

(Los Angeles District) plus the Northeast Cape Fear River study (Wilmington

District). Results of efforts related to environmental data management and

326
biological indices will result in savings by streamlining environmental data

mana-- .ent, eliminating the collection of redundant data, and reducing the

amy , of data required for a defensible environmental assessment.

PROJECT V

ENVIROIMENTAL IMPACT OF WATERWAY ACTIVITIES

i

Work in Project V consists of literature review and short-term field

studies of environmentall impacts of selected channeli'ation, bank stabilization, and navigation activities on waterways. This project is specifically

designed to complement and extend the applicability of results obtained from

the Waterway Field Studies.

Progress to Date

Prior accomplishments in this project include completion of a shortterm field study of Section 32 demonstration projects (Omaha District) and

publication of the results of the pilot study on the Mississippi River. The

latter is a series of reports detailing design, sampling, and analysis of

data for environmental studies of large waterways applicable to other,

similar projects.

Benefits

Knowledge on the environmental effect of waterway activities, especially

as it pertains to flood control and navigation project purposes, is required

to prepare meaningful and defensible environmental assessments, to develop

resource management plans that maximize project environmental benefits (plus

allow quantification of them), and as input to produce improved design and/or

operational guidance for Division and District offices. An excellent examr'le

of the application of these results is the direct application to environneental analysis of the Tennessee-Tombigbee project (Mobile District).

PROJECT VI

WATERWAY PROJECT DESIGN AND OPERATION FOR MEETING

ENVIRONMENTAL QUALITY OBJFCTIVES

Work within Project VI has concentrated on review of available design

and operations technology to meet environmental quality objectives as well

as the development of improved procedures based on the results of Project V

and the Waterway Field Studies.

Progress to Date

Prior accomplishment's include completion of an evaluation of current

design and operations technology for watzrway projects from available literature, CE Division and District offices, and other Federal agencies. Work

on the operational aspectv. of waterways projects has been completed and

guidance on improved methods for planning and construction of Section 205

Flood Control Projects (channelization) has been provided. Initial guidance

327
on the environmental impacts associated with the design of dikes, levees, and

streambank protection projects has also been developed zad provided to field

offices for review.

Benefits

Improved design and operations technology represents one of the most

desirable end-products of research on the environmental effects of waterway

activities. Given information on the environmental effects, improved techniques can be developed, and costs can be documented and compared to benefits

to produce guidance for Division and District offices on new design anJ construction concepts to meet environmental quality objectives. Since authorized project purposes are known, new technology developed within Project VI

ensures attainment of the primary objective of the EWQOS Program. The products of Project VI will minimize delays in waterway projects, facilitate

their efficient design, and maximize environmental benefits.

PROJECT VII

LONG-TERM FIELD STUDIES

Reservoir Field Studies

Long-Term Reservoir Field Studies include comprehensive, long-term work

at selected sites to meet multiple program objectives. The fundamental

objectives of these studies are to provide an understanding of cause and

effect between project design and operation and reservoir environmental

quality, and to obtain required data for technology development, demonstration, and verification.

Progress to Date

Prior accomplishments include the development of selection criteria,

screening of candidate reservoir projects, and final selection of sites.

The four study sites selected were DeGray (Vicksburg District), Red Rock

(Rock Island District), Eau Galle (St. Paul District), and West Point

(Mobile District). Following site selection, available data on all projects

were compiled and analyzed. Field studies have been initiated at all field

study sites under varying operational and seasonal conditions. Detailed

studies were concluded at DeGray and Red Rock sites to provide input to

other work within the program. A comprehensive data management program has

been established and analysis of data from all field study sites is proceeding. Detailed studies in support of Projects I and 1I are ongoing at the

Eau Galle site, and specific studies of reservoir processes have been performed at the West Point site. Guidance documents related to sampling and

reservoir processes have been provided to field offices.

Benefits

The primary benefit of the Reservoir Field Studies will be increased

understanding and information relating project design and operation to environmental quality objectives. This information is significant because it

328
can provide many answers to specific environmental problems related to

reservoirs and can be used in thL planning, design, and operation of reservoir projects. The results will minimize delays in reservoir projects due

to environmental questions and will provide the basis to correct many

environmental quality problems. Because of the selection criteria employed,

this information will be generally applicable. Data from the Reservoir Field

Studies will be used to verify techniques developed, demonstrate new or improved technology, and provide further insight into specific environmental

processes. Verified techniques and demonstrated technology have a distinct

advantage of producing end-products that are readily usable by Division and

District offices, have been fully evaluated, and thus facilitate technology

transfer. This will result in substantial monetary savings by avoiding

costly trial-and-error application of end-products. Similarly, if technology

to solve environmental quality problems at reservoirs is based on a thorough

understanding of a particular environmental process, then it will produce a

more usable end-product. Since the Reservoir Field Studies are performed at

operating projects, the results are more credible and do not require additional, extensive verification. New or improved guidance for sampling,

testing, and analysis of environmental data from reservoir projects will result in cost savings for monitoring or study efforts, and will produce data

that have meaning and usefulness to Division and District offices. These

results have been aphiled by numerous Districts in design of water quality

sampling programs with resultant cost savings.

Waterway Field Studies

The Waterway Field Studies consist of long-term, comprehensive studies

of waterway projects involving channel alignment, bank stabiiization, or

navigation channelization. The objectives of these field studies are very

similar to the Reservoir Field Studies: to provide information on the environmental effects of various waterway activities plus development of resource management plans and new or improved design and 6;eration guidance to

maximize environmental benefits or attain environmental quality objectives.

Progress to Date

Comprehensive field studies on a selected reach of the Lower Mississippi

River (Vicksburg District) and the Tennessee-Tombigbee project (Mobile District) have been completed. Data analysis is proceeding in conjunction with

Project V to prepare synthesis reports and environmental guidance documents

based on study results. Specific emphasis is being given to guidance on

study design, sampling methods, and data analysis for waterways.

Benefits

There is a significant lack of data regarding the environmental effects

of CE activities on navigable river systems. Results of the Waterway Field

Studies will provide valuable and urgently needed information to answer many

of the environmental questions raised by these CE activities. This will

result in minimizing project delays, more defensible environmental assessments, and reduction of costly litigation associated with more coatroversial

329
projects. Because of the lack of information regarding waterway activites, it

is difficult to claim environmental benefits associated with these activities,

determine possible mitigation actions, or justify modifications to

current design practice. Results from the Waterway Field Studies will allow

the development of resource management plans to maximize environmental benefits and provide a basis for their quantification, and will be used to

develop new or improved design procedures. These may result in larger project benefits for certain activities and minimize the costs required for

modification or possible mitigation. Some of the CE waterway activities fall

under the purview of regulatory functions. Knowledge of the environmental

effects of these projects will greatly reduce the costs and difficulty associited with the regulatory aspects for these projects. Improved sampling, testing, and analysis guidance for environmental data associated with waterway

projects will improve the efficiency of monitoring and survey activities,

reduce the cost due to unnecessary data collection, and make collected data

more defensible. Specifically, sampling and experimental design procedures

have been used by the Rock island and St. Paul District for environmental

studies of the upper Mississippi River. Results have also been applied by

the Mobile and Huntington Districts on studies of waterway projects. Results

from the Lower Mississippi Field Study have been directly applicable Lo additional environmental studies being performed by the Lower Mississippi Valley

Division at a significant cost savings.

PROPOSED RESEARCH

Under current plans, EWQOS is scheduled for completion in FY 1385; consequently, long-range objectives are oriented toward the successful completion of the programs. The objectives include the integration of task results

to meet project objectives, full utilization of field study results, production and distribution of end-products, and conduction of training (i.e.,

workshops) required to fulfill technology transfer goals. A continua] technology transfer effort throughout the conduct of EWQOS will ensure th.it results are directed to the proper user, are in the appropriate form for maximum utility, and allow feedback to the program as input to out-year research.

Complete synthesis of research results to produce logical and meaningful end-products will be the highest priority activity during the last year

of the program. EWQOS will provide three Environmental Engineering Manuals

within this series representing the culmination of a significant portion of

the research. Input to other Engineering Manuals is anticipated and will

be performed to the extent that need and desirability dictates. Other guidance documents such as input to ER's, EC's, and ETL's, design manuals, handbooks, and user manuals will complement input provided via Engineering

Manuals and provide the necessary information to meet EWQOS technology transfer objectives.

Conpletion of the EWQOS Program will represent a major milestone in environmeittal research and development associated with Civil Works activities

of the CE. Utilization of products produced from EWQOS are expected to produce sutstantial cost savings in solving envirorýnmental quality problems related tc: water resource management and development. Many of these benefits

330
can be attributed to reduction or elimination of conflicts between environmental goals and other project purposes, and improved procedures and criteria

for analyzing and solving environmental problems based on increased knowledge

of environmental consequences of Civil Works activities.

331
IWOOS STATUS SUMMARY. UEP 1

a. Pvof~ T~eefqs.. 6tOw eM g Emmms oem

LkARo mew., Hydrdynefflcil

v m ~a and vw@4y secti...q.,s for deserft- IL.. Was Sep at $ 1 atom Csew

2 Oweelso and enysecftioue f.,eatdecr*. EL WE&. Sal 4 2111011 ACe.., a"".gi algritwei, ev field .4 wwt~aU tsw" ms.".. plcamea MUsis a

* sam end "s.i, pftVWaf Cydt ytrnam HL. WMS Caa.0mct. Sea 1 220.000 C4e.4p. 9a,0twia .0".4 dacuinent mcdei.,q uillflqm eOt W.ew. Vs Urs

* lw~Oe" and as. 9 dm~~ HL. WIM NEC. Cow- Sao 64 3WOMg ACV.*.. s-.5st. ot wa ftyaoyst'e.. me~ i tsc. J a E n.4. Val 'ps's 0.0 (wq .tw,. pseficBatio

AssieO Nc@nped. TN aE-41-

5Oemft0 owd -S~fv fewqee ta decnn L. WIM Co.C..ct SOPa 1 46.00 Ac', oW-CW nsarse. iwld ag w

psps*awe"S plame Ga Techt Utint. basis cmeewa W.d ,tw TM E41-3

a ~a.of HIC-4 NEC S..tm 25000 Ceenpeos I Th betpsat of fine 2""W in~~w "t,~~a L. WIS sea at uMAN Ce-pest.. wet. asObfeend sm Ow of IC

as. Ififtvooe Omscnteton of ECOfog an sd

Waimer Cuafety Pvocam"a

Iý lamprot. sma v.#VA nwsdtaiidelog ad EL Was. 5WS Sea 63 7141UXI Ach.s .entw siqontfl.e for 08.C-OC dss'ebw .e-a.Pt .a~aOcap(aN)i USEPA; tooaeeswto.. &.it phyooanafstom hess pam...LM Ves" boew -a had and W*oteaed on sister osm"t ;tad TA E-40-3, TA E-40-4.

I'M E-41-13. UP E-41-2

2. Oweeme, end ""~ eatepmts. kat leatd IEL waEs S8044 mocom kq feldadMibo srWgeabic ctee.Cttaf ~ae.. "ttwy go q"efv wt~nas paam.s 'U.S udtet s ,-ab p, odi.tos; TA P414

4. latttwommo and .4..ewtu of Cseatvo ce CRNEL Sep £2 26.mg ACts.. smpfketc ifat~ton," deapd and

4m. and I4SI I a" Cthen"If w-"td Oat ".0".e

IC. MIs'eceWitter Ouallty and ECological P edictwe Tocfntnque

IC Improm snd vsif y, *.tNMAe o.*-dfsts.*a"~ EL WES 34944 900.0 A~.. cideffummins afs.,ef sefet

,W ".wa quedp and ecdologicalI o~dic -O

2. 08,ta Otd "teftumm. matiwssnese'4 EL WIM Seaga 3000m ACes. twe-ad~ssa,.f wade tested 'We-s.m wi vetw qd*tV and OCONNfall .q 9 fiUeld slad date seft

3 1 W~ae and 10"nf p 4nl WI et.alg Qu.w EL was. LSGS 56.8£ MAN~ Ads.. .e.sq at.-di.sno..fa .G.adw my~ end ecojaee pi steac mcR-aweo "Mat es- e twa-d,~ts*OsmI madel

teteicted toat ddition of "we. Quality

4 Fia etd oft CTh WORMS t wasets quiet Ppc Sea sop Is.og Cs..s

10. Daterm~naf ice of Loadings to fhesaotrs

I Evaluation. at ess...q technqesa,. for wilsct. EL waEs Sep ?I ?a O3 Cacepiet. TN E-4t-1 A asnnua Saedings to r.s.,avt1

CE. SJiopifte~d Tehcfinquee for PriediCtrnq Allow- EL. WES, COwt.Cl. Sell" 246.000 Acts.. dwat feow com~ettf. tocftftqt, fo. Yawt Wets.r Oafetp and Eutrophicatioe. w welt... tWatt.. e- 'naeo po,,sm tested. potential TIM 1-01-9

Teciliihfqumes

I14A. Management of Mutuance ACWg BSO"m m

A es.o. r.

OetCC, snd esefase attea calse. of EL. WES Sep ?I '60.060 Coevfee.. TNt E-00- I

r.,tmknc* afqM fef@ois -. CIE mw co.

2 00"1"ap sd fesuefuac nneieatac wsneqe.Cesi aE. Was. USIEPA Sep 60 135.000 Actie. ftetd studies unas way. TN E-8 $4

"n"wetad Cat roo a~~tf.t" g blfooms

3 Evaluatin f. @4 s-wiedaeted pftooaftaull EL. waEs L11,80 1EE 0610 Coinpfet.. TN F-liI18 Guidelines for Ostllt'i"minng R016114,11 to M"e

EnwvioC'.veente Ouslity 0b1 .clve.

I-4 Guamt,*ehne arde~nwI ong weeps, EL. WES. FVWS Sep 64 1.180.000 Actue. mnety"~ of held Studies Owocamedong. tee... to .,etm" atCeta qudalty INNNP)J C~ontrctS. b-ulwtfedbefootl .- Ow"t.e

OSCC~s~eOr J 0.,... lieature. w--. Oufef ahd. TA. E-41 -6,

CorwwifsC TA E-4t-C2 11C. Operatioal.e and Managementl Strategies Rfetwoir Contafinments

I &,wp of Che nalut s" agnitouds of EL. WaS S"p 75 20.00 CO.Coaee

ý comemns,-t aolobow" 2 Fate snd efttete o @4 tqot ctwetoc EL. WaES. Coe'tWe. Sea it 105.60" Co-veef

COf.Cttýt.C t I" eta, LSLI 110 Reservoir Regulation TecChnouee for

Waets Ouaeoy Meftegerntent

C seetno. -W-,ttO .%t,.t Ca EL. WaS Sao ?1 611000 Costotet

2 leseetaa., IsguldCO.. wC...que CW mL. was Sap 62 207o ACa.". 'sat M orvoamsCati.

NOTE: Aftoviattfons used inthi CRCS Wae. daflned as 1014t0"e

CANEL - Cofd Itiveas. Resewelantsd HL - Ntydrmsts Lsfabw"" ~ USAE U S Artey Ef~s LilbiW..n MYeoS~~ LSU L-o.w.- S1,at. Un-vm"aY USDA .U S Do" eiotw of Aqc~ufte

EI ttwos,,~ Ladorolay MPN -~e~~u Ps*O USEPA -U S EnewoontwaMC PotCeCIýf AqaR-y

I'W MOANN)- Fmt sd W~fd~de Ss.'tC IWSU OW- Ltmo.slat. 0i Un..C-" uS2S- U S Geoicq~cu Sc'.ay

(National Natena, ReesseeCC PMWOa.. OSU- W"oi't~.a SCC* Un'a-w. a WES ete.-sy EPeanne' Slat-O

Hec - ydMyaffcl Entgvtewtltt Ca.Ce TN.- TecRmwacl Naert

332
LEWOOS STATUS SUMMARY, SEP S1 (Concluded)

110 Asse~rt Rtegulation Techni~ques for Water

Quef" miinagsoetton jC~onsued)

3 moenew. 00e u..gw.0o for weim, NEC 30064 S 20M. Active, vso .eeo of NEC-dO ioc.glsbi

a.emmy CO."ro soAm ~'of ot is'loe iindsbeiall

lIE. Enwormomntll EVet of Fluctuaioog

filnoolrvo WOWr Lboes

IV09suldsn list IMMIN~fta SOW of MUKP ML. WES& UCA* Sao 114 mom. Activi. ft" 00900s Moisurew

-" 1*i" roeetimo~5illgidenced amraiabed TN4 E-M2

2 .~ sww EL WIES. FWS S69p ES nol% Acis". flitertr uiv anhd dat

14F. Flemero Shte Properaliof

1. Dowmilop praaod far a"rdi i EL WE&. FWSi. Ssp84 20[L= Actho. laboratory lauiftongoing90. 0190

PIPm6I.O , i flaw ip' USEPA an' Man pit rodu~ctiohn in W

it Tmh E- 41-Il

p. -agouo Toldwisismis ter Ume"" mamnulr

aW oumayo 0In si

IlA. Techniques to Ugitl Envrion ~tiIsi Qual"t

Obqechles. Ressirto Rolousis

1. Eluabil tells roe~wci dMIS M sillsu9 ML WES Sep 42 MO cM .r..~i. . a ,ovo

ouponouitioniii c0fttormmw. twoe TA's auil.TN E-41-5 and TA 6-41.13

2. Doeloist lscht iaues. W detemineso th. tresina HL WEE. Contiract Selp &l 314.00 C~ipowifi T04 E-40-6 gold TR E-4113-O

bthm powsta of structural E.~d~it~ C. T~norvoilo Inc

I. Evokisfl afterhtinnia. fW hbsisiOn/OxY90riind. WL WES S" 64 46.000 Actfc. field studies aid literature sun,"

aof hydropowuer thmrt olted

4 Dcb -Int thie-mc",- -1thPdrinnl hdriCtW~c.I. ML WMS Conractt S4914 444,00 Achw,. owsorll solectiv. uitlidluuil model

""oe oil voli~oullul OA t9igunoit nf mSU whissi

Ilils. ln-Allearvoir Techiotques for mrtnil

of Ellronrrmental Quality

i. EMuON thi lfi 0110twalf Of resevoi HL WIEE Consits Sop 4 211.011 Acthm,. fi"d toolia/ptfys" fil oddol"

uug/mruife teo chiwques 06k! studies oriq0.tt, -,Makd -- 9in

Laboartory studfies T1 E-std 1-7 MN 

2. Enroo ofleonte eff~cts ahssoitd with EL WIEE. Coutrols Slepst MEOOD Coniivual

,....o..o ooeoungd~sfowitW-c~b. Torsi Tee"i. inc.

4 Evoekief Ith. ~rfuc qofo ot tw- L WES Sap *I M00111 Coovpi UP E-61-3

IV. Eiwfrnrwueqifa Amememoim Tilmiiqums Jor -lsm and 1pe0 1 , flooorosn"

ivA. .~ilsmstmtl Tichinqiusis for Envrwirorifotal EL. WES. Coootrsct sepalI 74&000 Comipbeac TNI E-4002 sod Til E-41-4

Anarylks Un.. of Colo.

IVS. Oats Mhotegotrtlt and IndcA for

Ellmnr001rwital Asesothool~

1. Rinewe slid -eraejt data klinahsie,"tiiofIco- EL Was Sep60o 40.00 Conmplowe UP E-00,2

2 En~dhaflo .aefetd lpo".otoa nrdl010 tht iintGe EL WES Sep6& 1 i60.0 Cootpimal Inieroa wonootin document

polemtial .opt6cattor to ,.utpcl it

VA Environtmental Impact of Silecftd Cltit't'a EL WIEE. FWS Sap 1 64 11.000 Actroe. reults Of filed 0085 ia d Mthrul Itlo 

Alognto~t and Bank Rannitiriont Allternatoivs anstysi ongoing

onl Waterways

VEI Intpactil of Nirrijisiono Actiett"ls on fl., WES S" e - Ohayidl

Waterways

Vt WuterwMV P 000Cf 011sivelli Overseen far

VI A. Operational Procedures lof Waerflways

Protects to Arlam Enorrrontrisntla Quality

Iidentify. doeoturaoti and otoetuits the . .toc EL. WES Seps0 85.0 Cortoptif.. jrt~h woritirtg dtc.~obt

Of watrwnovey ehtsoooi Proce~dtwil 0010.n

quaotttlt itty

VI& Design and Construcl,00 Tachtnquus Mw

Waterwray Projects to Attson Environtmental

Quality Obleclteui

IIdeniftty,.5 -itha. docuttortt factors EL. WES Sep52o 1695000 Conopieve

,ft deignpt and contrutifon ,O f waterway Vwatic~ts ~iititg i'rtttttS Otaclinit

2D-.itoo and otosl.*t* -tio"-d Os"-o EL, WES S4p14 so2 Acrt,, rwr,054 6mgmt/construtlortt

Or.Csduo.. l04 stioo.Yo to guidatnce d-OihO~ttlo Ono.nq

"".otiOC ttto,"hentOaslt S4ilty Ior -. 1ta protect watgotleii

Vii. Long-Tortm Conoipriftholil Falid Studies

VItA. Resehrvoir Field Studios; Field Studis tor EL. WES. USGS. S.085 18000 Fsid stute Ongoting

Environtmental and Wa~te Ot-ilit Aspsct% USAE Distttct. Rock

of Reslervotir ISJin.C AM Witter

ID.Gtsy A--,tot Pnotrceio RAsCtt

2 Re oRtk fis.mrvo~ Cmontt 3 EAu Gal* RS-,irrt

4 Wit Fo~nt A -.'o

Vile, Wmtilt~wy Field Studoie: Long-T, in Field EL. WrES. DOE. Con- S"o as 2.S70,00 F.40 studis concluded. Analystl onodottg

Studis Associated witht the Envitonmtetntal tract. FWtS. Co-op

Quality of Waterwasy Projects Un~t .t LSfJ. Co-op

T-n~sia-Tonetgoti Utt1 oft MSU UiP E-80t. 1iRports1 t.8

R-7

Cortract. We"r Beach, Gross Nurtetilmi. Univ of S. 0sitoti. Southeastern OSU,

333 ' -- -V
>AD P0024 11

MARINE TECHNOLOGY FOR ENVIRONMENTAL PROBLEMS

-Some Examples of Improved Systems on WorkvesselsIchire Ofuji and Naoshi Ishimatsu

Japan Workvessel Association

Ishiko Building, 2-9-7 Yaesu, Chuoku

Tokyo 104, Japan

ABSTRACT

(PART I) For dredging and processing of loose sediments containing toxic materials, a system (in sequence)

of the following component processes- DredgingTransportation of dredged slurry, Dehydration and Processing of separated water, Unloading of cake solids,

Disposal (Reclamation) has proved most practical.

Operational cost for 50% soil concentration in the

dredged slurry is 10% lower than for 25% soil concentration and centrifugal dehydration gives 4% lower

costs than press dehydration. Depreciation of initial

investment, interest, and maintenance are three major

items consuming 22-28% of total cost of all the equipment. The processing barge for dehydration and water

processing is most costly, occupying some 60% of the

total cost.

(PART -I) The mechanism of sea surface turbidity

caused by overflowing water from a hopper dredge was

determined by model experiments to be due to air-lift

phenomenon of air bubbles entrained in the muddy water,

and the Anti-Turbidity Overflow System (ATOS) was developed to eliminate air bubbles from the overflowing

water. The effect of ATOS was confirmed by actual

dredging tests. In fine sand or silt, ATOS reduced

turbidity of the sea surface to as low as 10 ppm, or

lower in suspended solid (SS) concentration, as compared to a level of over 400 ppm without ATOS.

334

I. III

PART I. DREDGING AND PROCESSING OF TOXIC SEDIMENTS*

I.1 PREFACE

In Japan, because of industrial development, toxic materials deposited

into rivers or seas have settled on the seabed in harbors or bays at a level

high enough to cause a pollution problem. More recently, however, the pollution problem has become serious, and a practical method of dredging and processing the toxic sediments (which should be treated in a different way from

normal materials such as sand or silt) has not yet been devised, although a

few methods are undur development.

At the request of the 4th Port and Harbor Construction Bureau, Ministry

of Transport (MOT), the Japan Workvessel Association (JWA) formed technical

committee, consisting of engineers and experts from the Port and Harbor Construction Bureau, MOT, a university, and member firms of JWA, and conducted

studies of component processes (including model experiments) and systems evaluations to select the most practical overall dredging and processing system

for toxic sediments.

1.2 DESCRIPTION OF COMPONENT PROCESSES AND TOTAL SYSTEMS

1.2.1 Component Processes

The total system of dredging and processing of toxic sediments is divided

into the following component processes:

- Dredging

- Dehydration (Separation of solid sediment and water)

- Processing of separated water

- Transportation of processed material

- Unloading of processed material

- Disposal of processed material (Reclamation)

1.2.2 Total Systems

Assuming that all component processes except dispopal of processed

material are done at sea, the following combinations (systems) of component

processes were taken up for comparison and evaluation (Figure 1.1). Processes

in each square are assumed to take place on single, indpendent, floating units

in the sequence indicated by the "system flow."

The last process, disposal, is closely related to land reclamation and

not discussed in this study.

* Part I of this paper is derived from the original report (in Japanese) entitled "Study on the Development of Dredging and Processing of Loose Sediment Containing Toxic Material."

336
System No. System Flow

I U oa (lsposaI)

II l-drarora ad Transportation Unloadi (Disposal)

Il iDredging -Transporcation Unloadion -(Disposal)

Dehydration

Water Processin

IV IDredging - Dehydration HDUnodin i-(Disposal)

Water Processing

Transportation = -

V Dredging HTransportatio)n~b Dhyd ration : Unloading 'Disposafl. [ 1 1 ' I I_[Water Process mg

Figure 1.1 Total system flow of dredging and processing of toxic sediments

The purpose of the study was to select the most practical system, of the

four' studied, for dredging and processing of toxic sediment. The study was

conducted in two phases:

- Preliminary studies of component processes, and

- System design studies and evaluations based on the preliminary study.

1.3 PRELIMINARY STUDIES OF COMPONENT PROCESSES

Methods for each process were studied and actual tests were conducted to

confirm their practicality.

1.3.1 Dredging

Study Outline

Six different dredging heads of three types (Ejector, Suction Pump, and

Vacuum Tank) were proposed for initial study and the Committee selected two

heads, Submergible Centrifugal Pump (lower positioned), and Pneuma Pump for

the actual dredging test.

For transfer of dredged material from the dredging head to the following

processing stage, the Pressure Transfer System was selected over three other

systems (Ejector, Vacuum Transfer, and Air Lift).

337
Test Results

Both the Submergible Centrifugal Pump and the Pneuma Pump dredged loose

sediment at approximately the same level of soil concentration and reached as

high as 50%, on average, except in the lowest cases. In total, the average

soil concentration was 40.0% with Submergible Pump and 43.6% with Pneuma Pump.

1.3.2 Dehydration

Study Outline

Four methods were studied:

- Thermal dehydration

- Chemical dehydration

- Electrical dehydration

- Mechanical dehydration

The Committee judged that mechanical dehydration was the most practical for

.dehydration of rather loose material, of the four methods studied. Although

six types of equipment were proposed for mechanical dehydration (Roll Press,

Filter Press, Vacuum Filter, Centrifugal Decanter, Cyclone, Pallet Blanket),

two (Roll Press and Cyclone) were judged obviously impractical for the purpose in terms of processing effectiveness or ease of running on a ship and

only the remaining four were tested.

Test Results

Water concentration (by weight) in the cake processed by each dehydrator

was as fellows:

- Filter Press 40-43%

- Vacuum Filter 55%

- Centrifugal Decanter 43-53%

- Pallet Blanket 53-60%

1.3.3 Processing of Separated Water

Outsine

Water separated by dehydration processing contains a large amount of suspended solids (SS) together with toxic materials such as heavy metals like

mercury and cadmium or their compounds. Discharge of water to the open sea

is allowed only after it is processed to such an extent that the concentration of toxic materials is less than a permissible level.

The Comittee considered four processing methods (Coagulator, Tube

Separator, Floatator, Sand Filter), and selected the following combinations

to be tested:

338
- Coagulator + Sand Filter

- Tube Separator + Sand Filter

In the tes¶, the loose dredged material was dehydrated and the separated water

was processed through each of two combinations. PH, COD (chemical oxygen demand), and the concentration of SS and heavy metals in the processed water

were measured.

Test Results

SS concentration in thb water processed through either one of both combinations was less than 10 ppm and the ratio of residual heavy metals to SS

concentration was on the order of 10-4 both with mercury and cadmium.

This means that heavy metal concentration can be reduced below the permissible level (mandatory restrictions) by keeping SS concentration under

10 ppm.

1.4 SYSTEM DESIGN EVALUATION'

Following the preliminary studies, alternative total system designs were

evaluated by cost comparisons covering both construction of the equipment and

operation thereof.

1.4.1 Preliminary System Evaluation

Of the four systems to be evaluated against the basic reference system

(Figure 1.1), Systems III and IV were excluded on the basis of preliminary

evaluations.

System III requires that all equipment for dredging, dehydration, and

water processing be installed on one floating unit of relatively large size

which will result in difficult operation. The processing flow of System III

is the same as that of System II 3nd its cost can be estimated based on

System II.

Similarly, in System IV, all equipment for dehydration, water processing,

and transportation should be aboard one barge fitted with a large capacity

retaining tank for toxic sediment and water, together with a holding tank for

dehydrated cake due to the nature of the system operation cycle. It is obvious that System IV will be most costly in consideration of size, construction cost, and operation cost.

Detailed evaluations were therefore limited to Systems I (the reference),

II, and V.

1.4.2 Design Conditions

Dredging

- Material to be dredged

339
Loose sediment containing toxic material (Hg, etc.)

Water ratio to wet (solidified) sediment (by weight) 150%

Water concentration in wet sediment (by weight) 60%

Specific gravity of dried sediment 2.55

Apparent specific gravity of wet sediment 1.35

- Dredging site

Dredging depth 10 m

Thickness of sediment layer to be dredged 1 m

- Average soil concentration in the dredged slurry

(volumetric percentage of wet sediment) 50% & 25%(*1)

- Equipment

To be of type not to cause secondary pollution, i.e., spill of

dredged slurry or disturbance of sediment near dredging head

- Operation

Hours/Day 10

Shift of crew None

*Note 1: 25% concentration was assumed for last phase of dredging when excessive layer of sediment free of toxic material may not be

dredged.

Dehydration

- Residual water concentration in dehydrated cake - Less than 50%(*2)

- Operation

Hours/Day 24

Shift of Crew 2/day

- Capacity To match dredging capacity based upon

respective operation time

*Note 2: Decided in consideration of toughness of land reclamation.

Processing of Separated Water

- Residual SS Less than 10 ppm (*3)

*Note 3: 10 ppm was proposed based on preliminary study which proved that,

by keeping SS less than this level, the concentration of heavy

metals can be maintained below the mandatory restriction.

340
- Operation

Hours/Day 24

Shift of Crew 2/day

- Capacity To match dehydrated capacity

- Monitoring of processed SS concentration is to be automatically

water recorded with alarm system to stop

overboard discharge pump

Transportation

- System Pusher/Barges

- Distance 5 km (one way)

- Speed 7 Kt

Unloading

Equipment Material To

System Unloading Site Be Unloaded Unloading Equipment

I Transport Barge Slurry Pump (aboard barge)

II Transport Barge Dehydrated Cake Clam Shell Unloading

Barge

V Processing Barge Dehydrated Cake Conveyor (aboard processing barge)

In System V the dehydrated cake is unloaded directly by conveyor system

and no holding tank of the cake is required.

Other Conditions

All equipment is installed on one floating unit such as a dredge, processing barge, or transportation barge. Elt.tric power for the pump aboard

the transportation barges will be supplied from the processing barge or from

the shore.

Disposal of unloaded material is considered land reclamation and is

ignored here.

1.4.3 Equipment

Based upon the design conditions described above, the following equipment

was proposed for the system design:

341
Dredge

Type Pump dredge with ladder

Dredging depth Max. 17 m

Dredging head Pneuma Pump

Dredging capacity 200 cu.m/h 270 t/h (wet sediment)

Pump capacity 400 cu.m/h 475 t/h (for 50% soil

concentration)

800 cu.m/h 885 t/h (for 25% soil

concentration)

The most essential point for selection of the dredging head is to secure

the highest soil concentration to minimize the cost of subsequent processes.

For this purpose, the Pneuma Pump was selected, and the maximum dredging capacity availableat the time of study was approximately 200 cu.m which was

selected for this design.

Dehydrator

The following two types of equipment were selected:

- Filter Press

Water concentration in dehydrated cake 40%

Required dehydration capacity-slurry 166.5 cu.m/h (198 t/h)(*l)

333.5 cu.m/h (369 t/h)(*2)

Yield of cake 46.5 cu.m/h ( 75 t/h)

- Centrifugal Decanter

Water concentration in dehydrated cake 50%

Required dehydration capacity-same as Filter Press

Yield of cake 61.5 cu.m/h ( 90 t/h)

*Notes 1 & 2: For soil concentration in the dredged slurry of 50% (*1) and

25% (*2), respectively.

Water Processor

Type Either coagulator + sand filter, or

tube separator + sand filter

Required processing 120 (105) cu.m/h (*I)

capacity 287 (272) cu.m/h (*2)

*Notes 1 & 2: For soil concentration in the dredged slurry of 50% (*1) and

25% (*2), respectively. Figures in parentheses are for water

concentration in the dehydrated cake of 50%.

342
SS concentration in Less than 10 ppm

the processed water

Monitoring system Automatic recording with alarm system

The Dehydrator and Water Processor were assumed to be installed on the

same floating unit (processing barge) in consideration of continuity of processing. In addition, a conveyor system was fitted on the processing barge

for unloading of dehydrated cake onto a transportation barge or onto land.

Transportation Barge

Type Barge with open hopper and no bottom

No. and capacity door. See Tables 1.1 and 1.2

Unloader

Type Barge with clam shell unloading grab

Capacity of clam

shell 3 cu.m

This unloading barge is required in System II. In System V, the dehydrated cake is unloaded by the conveyor system aboard the processing barge.

Electric Generator (System I only)

Type Independent diesel engine driven

generator

Capacity 100 KW (for soil concentration 50%)

200 KW (for soil concentration 25%)

Electric generator is to be installed ashore at the unloading-site to

supply electric power to the pump aboard the transportation barges.

Summary Table of Equipment

Equipment designed for this system study is listed in Table 1.1. In

total, 23 units of equipment were designed initially, of which 21 were

utilized to assemble the systems.

1.4.4 System Configuration and Cost Estimation

System Configuration

System configurations or combinations of processing equipment are shown

in Table 1.2. System Ill is for reference to study the cost when dehydration

of 10 hours per day is applied. In this case, dredged slurry is dehydrated

continuously after dredging. This system requires a dehydrator with capacity

of two times that of System II but the slurry holding tank may be substituted

by a separated water tank smaller in size.

343
04

oo ca (aU n WN

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Cost Estimation

- Cost items

Depreciation of initial cost

Interest

Manning

Maintenance

Fuel

Chemicals for water processing

Overhead and others (insurance, port dues, contingencies, etc.)

- Lifetime of equipment (assumed)

Dredge 7 years

Transportation barge 12 years

Processing barge 7 years

Unloading barge 7 years

Electric generator unit 7 years

Estimation method

First, based on cost items and lifetime, annual cost was calculated on

each unit of equipment (23 in total), and then the various system costs were

determined from the'proper combination of unit costs.

Estimated system cost is shown in the extreme right column of Tables 1.2

and 1.3 by ratio to the cost of model No. 9 of System V which was the lowest

except System I.

1.4.5 Cost Comparison and System Evaluation

Cost Comparison

- Total cost by system corfiguration

As shown in Table 1.2. configuration No. 9 of System V (DredgingTransportation-Centrifugal dehydration and water processing-Unloading-Disposal)

for dredged slurry of • soil concentration is the system of the lowest cost.

On the other hand, the system of the highest cost is No. 6 of System II

(Dredging-Centrifugal dehydration and water processing-TransportationUnleading-Disposal).

- Averaged cost by system

System Total cost ratio

II 1.2

II 1.5

V 1.0

346
This indicates that System V is the most economical.

- Cost by soil concentration in the dredged slurry

Soil concentration(%) Total cost ratio

50 1.0

25 1.1

In other words, if average soil concentration goes down to 25% from 50%,

the annual cost will increase by 10%.

- Cost by dehydration method

Method Total cost ratio

Press Filter 1.04

Centrifugal Decanter 1.0

- Cost ratio by equipment (Table 1.3)

Table 1.3 shows percentage of annual cost for each unit of equipment compared to the total cost. Of the equipment, the processing barge is the most

costly, requiring 60 to 70% of the total annual cost.

- Itemized cost ratio

In the case of System V with soil concentration of 50% in the dredged

slurry, the cost percentage of each item to the total cost is as follows:

Item Press dehydrated Centrifugal dehydrated

Depreciation 25 22

Interest 23 21

Manning 5 5

Maintenance 28 24

Fuel 2 6

Chemicals 0 5

Overhead, others 17 17

Total 100 100

System Evaluation

As described above, System V (Dredging-Transportation-Dehydration and

water processing-Unloading) was the most economical system. This is because:

- System II and II1 require an unloading barge independent of other

equipment, while in System V dehydrated cake is unloaded by conveyor

system aboard the processing barge.

347
P- PI 1- pp 1

cc40 00 r,

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oo coL

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-4. z 461==I

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"434
- System V requires less tankage than II and III, thus the processing

barge can be smaller.

Higher soil concentration in the dredged slurry reduces the total cost

but the rate of cost increase due to reduction in soil concentration is not

so drastic. It is noteworthy that low cost dredging, with rather low or

medium soil concentration, would lower the total dredging cost.

System I, without dehydration and water processing, used as a reference,

showed relatively lowest cost. This study did not include land reclamation

costs, which should not be neglected in an actual case.

I. 5 CONCLUSIONS

The Committee concluded, at the time of this study, that the most economical system for dredging and processing of loose sediment containing toxic

materials consists of the following sequence of component processes:

1. Dredging.

2. Transportation of dredged slurry-mixture of sediment and water.

3. Dehydration of dredged slurry and processing of separated water to

discharge overboard.

4. Unloading of dehydrated cake to the land.

5. Disposal of unloaded cake (reclamation).

Although such a system has not yet been implemented, it is our hope and

expectation that this study will pave the way to utilizing an effective system of dredging and processing of toxic sediments to the ultimate benefit of

society.

349
- Ij

'4 PART II. ANTI-TURBIDITY OVEJFLOW SYSTELI FOR A HOPPER DREDGE

II.1 PREFACE

Another serious problem about protection of the environment is turbidity

accompanying dredging operations, especially hopper dredges.

Turbidity is defined as coutamination or disturbance of water caused by

dirty subqtances like dreoged sediments or sludge.

In dredging operations by a hopper dredge, the excess water in the

hopper is discharged overboard in the interest of high dredging efficiency.

However, this produces turbidity of the seawater around the dredge and, by

the action of tidal currents, winds, or trailing of the dredge itself, the

disturbance is often spread over a wide area. Should some resort beach,

fishing groumds, or marine cultivation farm (for seaweeds, pearls, or fishes)

be in the proximity of the dredging site, the turbidity may cause serious

damage. In some areas in Japan, where trailing hopper dredges have been engaged in dredging of harbors or navigation channels near seaweed cultivation

farms, the dredging operations were sometimes restricted or suspended because

of this problem.

In light of this problem, a joint study was made by Ishikawajima-Harima

Heavy Industries Co., Ltd. (IHI), the shipbuilder, and Tokushu-Shunsetsu Co.,

Ltd., the owner and operator of a hopper dredge. As a result, the AntiTurbidity Overflow System (ATOS), which effectively prevents turbidity of the

sea surface in hopper dredge operations, was developed and retrofitted on

all the hopper dredges with hopper capacity of 1,000 cu.m and above now working in Japan.

ATOS was first introduced to the world in an award-winning paper giver.

at the Seventh World Dredging Conference, San Francisco in July 1976. Since

then, some improvements have been added to ATOS and tests have been conducted

to collect further data to confirm the effects of ATOS' This paper reviews

the development of ATOS first and then discusses the additional test data and

analysis.

ATOS has been highly accepted in Japan and commended by the Secretary

General of Science and Technology Agency, 1976, and by the Minister of Transport, 1980, for its contribution to sea environment preservation.

11.2 CONVENTIONAL OVERFLOW SYSTEM

The conventional overflow system most widely used now discharges the

overflowed water onto the sea surface (Figure II.1) making the surrounding

sea surface turbid (Figure 11.2).

Another type of conventional overflow system is shown in Figure 11.3

where an overflow chute is led to an underwater port on the hull side or bottom through which the excess muddy water is discharged. It would be expected

that the sand particles or other substances contained in the muddy water might

350
Figure 11.1, Conventional overflow Figure 11.2 Overflow of muddy water and

system (Ex. 1) t~urbid sea surface

4'~ &4

Figure 11.3 Convetv jonal overflow

system (Ex. 2)

settle toward the seabed without causing turbidity of the sea surface. But

this is artually not the case, as the disturbance rises up to the water suLface (Figure 11.4) and spreads widely over the surrounding area with little

improvement in the turbidity problem (Figure 11.5).

Figure 11.4 Overflow through a chute

opened underwater

351
ii

L,4

Figure 11.5 Turbidity

abaft dredge

A third system is similar to the second one but with the overflow chute

extended well below the hull bottom so as to discharge the water free of the

agitation caused by the stern propeller. But this system is not as effective

as would be expected either.

Figure 11.6 shows an example of spreading of turbidity measured by

aerophotography in the case of a 500-cu.m hopper dredge "Daisen-Maru" engaged in dredging silty sand off Sakaiminato, Tottori prefecture, northwestern

part of Honshu Island, Japan. As shown here, turbidity remained on the sea

surface for a long time and spread over a wide area as time passed.

Precisely how is the sea surface made turbid by the muddy water overflowed through various types of overflow systems? To answer this question and

to probe into the mechanism of the turbidity and thereby devise a countermeasure to suppress the turbidity, model experiments were conducted and

followed by actual dredging tests.

11.3 ANTI-TURBIDITY OVERFLOW SYSTEM (ATOS)

In this section, the develpment of ATOS is briefly reviewed. References

(1) and (2) provide more details.

11.3.1 Model Experiments and Mechanism of Turbidit 1

Using 1/20 scale models of overflow system of "Tokushun-Maru No. I," a

4,000-cu.m trailing hopper dredge, a series of model tests was carried out to

probe into the mechdnism of turbidity by simulating overboard discharge of

the excess water, in some cases mixing fine sand into the overflowing water.

352
MMfONOSMaK CHO

' 13

.1.4

.2.

(( Figure II.6 Result of investigation on a

i turbidity spreading

As a result of the model experiments, the turbidity of the water surface

was inferred to be attributable to an "air-lift" phenomenon with air bubbles

contained in the overflowed water. In the overflow process, numerous air

bubbles are generated and entrained into the overflowed water and discharged

overboard, where the air bubbles well up to the water surface forcibly lifting

surrounding solid particles, resulting in turbidity of the water surface.

Accordingly, the turbidity of the sea surface was presumed to be preventable

by the elimination of air bubbles from the muddy water discharged overboard,

thus allowing isolid particles of sand or other substances to settle rapidly

toward the sea bottom.

Based upon this conviction, the Anti-Turbidity Overflow System was developed and retrofitted on "Tokushun-llaru No. 1" for an actual dredging test.

11.3.2 Anti-Turbidity Overflow System (ATOS)

The model, experiments suggested that the overboard discharge of air

bubbles could be prevented by three counterIeasures:

(1) Minimizing, the generation of air bubbles in the process of overflow,

(2) Removing air bubbles, if generated, from the overflowed water before they are discharged overboard,

(3) Discharging the overflowed water (once made free of air bubbles) with care

to prevente entraining of air again.

353
S/ /

•..~.. * ) '4: /

bolt. *we

Figure 11.7 Anti-Turbidity Overflow System

The Anti-Turbidity Overflow System (ATOS) shown in Figure 11.7 embodies

these three countermeasures, each of which is discussed below:

(1) The inclined baffle plate in the overflow trough receives the overflowed water before it gains falling energy and streamlines the flow, thus

suppressing the generation of air bubbles.

(2) The overflow trough is divided into two parts to give the flow longer

passage to permit the flowing water to remain in the trough long enough for

the air bubbles still entrained to float up to the water surface and disperse.

The flow-regulating gate, the essential part of ATOS, located at the entrance

of or in the overflow chute, keeps the water in the overflow trough above a

certain level. Model experiments showed that the water in the overflow trough

must be maintained above a certain level to allow air bubbles to float up to

water surface and disperse into the atmosphere before they reach the entrance

of the overflow chute. The flow-regulating gate, driven by a hydraulic

cylinder, is controlled remotely or automatically in response to a signal from

a level gauge installed in the overflow trough.

(3) The overflow chute is enclosed and opened to the bottom of the

dredge. The air could not be entrapped again and solid particles in the

muddy water settle toward the sea bottom rapdily.

The successful application of ATOS to full-scale dredging operations is

described in Section 11.4.

354
11.3.3 Installation, Retrofitting, and Operation of ATOS

As described above, the configuration of ATOS is rather simple and ATOS can be readily installed on a new dredge during construction or retrofitted

on existing dredges in service. In new construction, ATOS can easily be

provided for during the normal design phase.

The operation of ATOS does not require special skill or experience because the remote or automatic control of the flow-regulating gate is the only

apparatus to be adjusted during operation.

Figures 11.8 and 11.9 show the ATOS retrofitted on "Hakusan-Maru," a

1,300-cu.m hopper dredge owned by Ministry of Transport, Japan, and a diagram

of automatic control, respectively.

The overflow trough near the chute inlet is fitted with an ultrasonic

level sensor to transmit signals to the control board where the level transmitted is compared with the predetermined high level and low level. When the

level goes out of the range between the high and low level, the control board

automatically sends a signal to the hydraulic power unit to move the flowregulating gate so as to bring the water level in the trough within the preset

range.

Normally, the flow-regulating .,lve is operated between upper and lower

points set by limit switches for s;-%oth and precise regulation. Should the

water level go higher than the upper alarm level or lower than the lower alarm

level unexpectedly because of an abrupt change in flow volume or other reasons,

the regulating gate is instantly opened fully or closed (as required) to

prevent the overflow of muddy water beyond the hopper coaming, or overboard

discharge of air bubbles. Quick and precise response to fluctuation of water

level is a vital feature of this automatic control system, and ultrasonic

sensing was selected in consideration of this and other favorable features.

The automatic control system of ATOS on "Hakusan-Maru" has been reported

to be working smoothly and without trouble.

11.3.4 Dredges with ATOS

Since the introduction of ATOS, four out of five hopper dredges now

in service in Japan have been equipped with ATOS. Table II.1 lists those four

dredges with their pincipal particulars. In addition, the fifth dredge

"Kairyu-Maru" (replaced by "Seiryu-Maru") was tentatively equipped with ATOS

for dredging tests.

"Seiryu-Maru," the latest dredge, was equipped with ATOS from "birth."

The other three dredges were retrofitted with ATOS, taking advantage of the

time out of service for annual drydocking.

355
Ukaoaac sensaL- &transmitter CHvdI rpullc~cYlinmc

Water levelga u

__igher alarm level

-HAigh lev ei.

~--Center leveL -)Normnal CrirA..awlevel - _ .__ )atton range

_.aWejklaXrljevel

Ovc rflow c hute Hopper

Figure 11.8 Overflow system of "Hakusan-Maru't

4_,lrsncsensor jnicatit

'& tranism it-te-r-

* F e sigaa - Inict

e, ~ -trough Contra

con verter -circuit

Hydraulic power unit

Figure 11.9 Control diagram for automatic operation

356
11.4 EFFECTIVENESS OF ATOS WITH ACTUAL DREDGES

The effectiveness of ATOS has been confirmed by a series of actual dredging tests with the following hopper dredges.

11.4.1 "Tokushun-Maru No. 1"

This is the first hopper dredge equipped

with ATOS. The effectiveness was very conspicuous on this dredge. As shown in Figure II.10, sea surface turbidity cannot be

seen. Data on SS (suspended solid) concentration in the water sampled at 5 m below

the sea surface around the dredge (when

dredging soil of mostly sand) varied from 2 ,

to 9 ppm, which is just slightly higher than

before dredging. This fact implies that sand

particles in the overflowed water settled directly toward the sea bottom after overboard

discharge without causing surface turbidity.

Figure II.10 Clear surface side by

"Tokushun-Maru No. 1"

with ATOS

11.4.2 "Kairyu-Maru"

This 2,000-cu.m hopper dredge was engaged in maintenance dredging of navigation channels in Nagoya Harbor where the seabed is covered with silt

and clay mixed with sludge, i.e., soils of very small particles. To collect

basic data for the planning of ATOS for a new dredge to be built (later named

"Seiryu-Maru"), a series of dredging tests with "Kairyu-Maru" was carried out

by the Fifth Port and Harbor Construction Bureau, MOT, and the Japan Workvessel Association. ATOS was installed on the port side with the conventional

overflow system on the starboard side to compare the effects of both systems

under identical conditions.

Three cases were studied - overflowing the muddy water independently

through ATOS and through the con-'entional system, respectively, and simultaneously through both systems. For each case, the transparency of the seawater at both sides of che dredge as well as at the stern was measured. In

addition, seawater at the surface and I m below the surface was sampled for

SS measurement.

357
a'o JA Al x x x- 140 0 ~) N 0 - 3 w X (n~ r-.

C4.

to C%4

0: (Ub- ~~2* 4) 0) 4.J 1 1 - M414 ( An- '0 00Q - UO 00 0 Z 000 0 ~~~~~~~~~> 0 0 4 44 O 1 - . .~( . . . . 0. U ' U ,UM 

10 0 4 N V4~0~

-4

w' 14 -

0 c0

:3 O' 19 X 0Mww. w oL m 0 00

w~ Q M N0 91 C6C3)ýc 4

mI 4) -0 10 '0 LM1 X . on- 1 1 4 ~ 0 0 U 0 S U 0 0 , Ie

w4r - F- a %n 3c an0c 

A4 0. 0% 0a~

_1 N (M

-: X .

-4 tU0q)144 04 00 x 0 to r-4 e- a X4 faw XA r41ý - 14 00 41 ,.. ~ 00 ' 0 mN 00 :=31 0 4.4 ca 00 0 0. -0 4.4 m~ 00 0. 00 0. 0

14 .%. S4 4) 12. 1w 14 0

.4 u Q . 1 o 0

.0 0 -~ U 0 V '358
Figure 11.41 Turbidity side by Figure 11.12 Cleir sea surface side by

"Ka i ryu-Ma ru." "Kairyu-Naru" with ATOS

without ATOS

The results proved that ATOS is very

effective against soil of small particles

like silt and clay. Figure II.11 shows

the turbid sea surface on the starboard d--5

side where the muddy water overflowed

through conventional overflow system,

while no turbidity can be seen either

at the side or stern when overflowed f C_- "-.-- ...

through ATOS as shown by Figures 11.12

and 11.13. Table 11.2 lists water

quality data accumulated through these

tests. Whereas the water quality at

the sea surface is conspicuously de- f

teriorated by overflowed water with the

conventional overflow system, the excess Figure II.13. Clear sea surface

water discharged through ATOS hardly de- abaft "Kairyu-Maru"

grades the water quality, with ATOS

Figure 11.14 shows the contrast in water quality, with and without ATOS,

more clearly. SS concentration without ATOS went up rapidly with repeated

dredging while it remained at the same level with ATOS throughout the tests.

11.4.3 "Kaiho-Maru"

ATOS retrofitted on "Kaiho-Maru" was tested by the Port and Harbor Research Institute together with the Fourth Port and Harbor Construction Bureau,

MOT (3) (4). In the test with "Kairyu-Maru," seawater was always sampled

at the side and abaft the dredge during dredging; in other words, the sampling

spots moved with the dredge. Contrary to that case, sampling spots for

"Kaiho Maru" were fixeO at four positions (E, G, F, D), located downstream

of the tidal current from the dredging site as shown in Figure 11.15.

359
4,

-: 1.4 .

041

cEl 0 4 '"m~.9.1 41

-

410

- .

41 CD a

C6 4) -

00 0 0 a-.

0 1..

CA 41

cm 0 ej 0 .4 

0 41

34)

040

4 "0

t4 3

C:

00

04

0 0 

41 41 41

U ~ 6.00.190 0 ~ I '-~O'- IN04 3 W(66 0 0 1X

36
/

//

//

304

i- S 0-0 surface MAO -WJ L A ATOS

20

__ 0 0 - -

A8 4

- , S a

Figure 11.14 Effect of ATOS on water quality, dredge "Kairyu Maru"

361
+-,,

Figure 11.15 Dredging site and sampling spots

At each spot, a sampling boat was

assigned to sample seawater at depths

of 0.5m, 3m, 5.5m, 8.0m, 10.5m, and

13m, as well as at the surface. Figure 11.16 shows turbidity and sampling

boats during the tests. The dredging

site (Fig. 11.15) was located in the

middle of Kan-mon Strait, known for

its swift current. Dredged material

was silty sand.

Figure 11.16 Dredging tests with

"Ka iho-Mia ru"

An analysis of SS concentration in the sampled water is graphed in

Figure 11.17.

Without ATOS, turbidity increased with repeated dredging and SS concentration reached as high as 400 ppm at the end of the dredging tests. With

ATOS, turbidity increased little at every depth and SS remained nearly constant at a level of 10 ppm. In this test, vertical distribution was also det-rminee and A distribution pattern as illustrated in Figure 11.18 is derived

from theoretical analysis based on the collected data (4). ATOS has another

362

//
so.

without ATOS

~-3.

A1-0.

20

>10

20 1UN 2 34 5 67 _

50 100

T (min

For Silty Sand

Figur 111 fec fAOSo aerqaiydeg

">aih 1ar0 (atpintD)

0 AUN 2 3 5363
w t TOS

with ATOS

Figure 11.18 Vertical distribution

of turbidity

effect: the lowering of the distribution of turbidity well below the water

surface. This implies reduction of the spreading of turbidity, because, in

an area like an estuary where continuous maintenance dredging is required, the

current velocity decreases as the water depth increases.

11.4.4 Other effects of ATOS

In trailing hopper dredges, seawater is used for cooling engines and

various heat exchangers, fire fighting, washing, ballasting, etc. Seawater

for all these purposes is taken by pumps through suction inlets on or near

the hull bottom under the machinery room, normally located aft of the overflow

chute. As easily understood, solid particles contained in the overflowed

water (ould clog the strainers or filter in the pump suction line or damage

pump impellers or packing. With ATOS, such solid particles settle rapidly

toward the sea bottom before reaching the suction inlets, thereby avoiding

these problems.

364
11.5 CONCLUSIONS

Through actual dredging tests, ATOS has proved to be very effective for

preventing the turbidity of the sea surface that accompanies conventional

dredging operation by hopper dredge.

To obtain the advantages of ATOS, the following three conditions must

be carefully studied before application:

(1) The suppression of the generation of air bubbles in the process of

overflow by providiag an inclined baffle plate or other similar measures.

(2) The retention of the overflowed water above a certain level in the

overflow trough at a speed slow enough for the ai. bubbles to rise up to the

water surface and disperse into the atmosphere. But the flowing speed should

not be too slow to avoid settlement of solid particles in the trough.

(3) The discharge of muddy water overboard underwater, preferably to the

dredge bottom, through an enclosed chute to avoid contamination with open air,

i.e., to prevent air bubbles from being entrained again.

Fortunately, ATOS has been welcome in Japanese dredging circles as a

means of easing social problems. Japan is known for its fisheries and there

are many cultivation farms or beds of yellowtail, pearls, or seaweed, etc.,

all of which are vulnerable to dirty water. Should, turbid water flow into

such farms or beds, the dredging operation would be subject to instant suspension resulting in social problems. As 3 matter of fact, "Kaiho Maru" was

to be in such trouble before being equipped with ATOS, but she has been able

to continue maintenance dredging in the Strait of Kan-mon where fertile cultivation farms of seaweed exist near the dredging site.

So far, ATOS has contributed to the easing of social problems arising

from turbidity, but efforts for possible improvement of ATOS or development

of other systems to prevent sea pollution will be continued by all people concerned with the problem in Japan.

365
REFERUCES

1. Ichiro Ofuji, Naoshi Ishinatsu: "Anti-Turbidity Overflow Systems for

Hopper Dredges," Proceedings for the Seventh World Dredging Conference,

San Francisco, Calif, July 1976.

2. Ichiro Ofuji, Naoshi Ishimatsu: "Anti-Turbidity Overflow System for a

Hopper Dredge," IHI Engineering Review, Vol 10, No. 1, Jan. 1977.

3. Yoshikuni Okayama, Yasuji Saotome: "Turbidity of Sea Surface by Hopper

Dredges and Effective Preventions," Sagyosen No. 135.

4. Tokuji Yagi, Yasuji Saotome et al: "The Investigation on Turbidity due

to the Drag Suction Dredger," Technical Note of the Port and Harbour Research Institute, Ministry of Transport, Japan No. 279, Dec. 1977.

366
ADPoo2 4 12

MOUNT ST. HELENS ERUPTION, CORPS OF ENGINEERS RESTORATION EFFORTS

J. F. Bechly

Waterways Maintenance Branch

Navigation Division

U. S. Army Engineer District, Portland

P. 0. Box 2946

Portland, Oregon 97208

ABSTRACT

.. •On 18 May 1980, Mount St. Helens in Washington

State experienced a large magnitude volcanic eruption,

which severely imoacted the surrounding area and the

channels of major streams having their sources near

the mountain. One of the more significant impacts was

the filling in of the flood control and navigation

channels of the Cowlitz and Columbia Rivers. Immediately thereafter, the Corps of Engineers undertook a

massive program to restore both navigation and flood

carrying capacity of these streams. This paper summarizes primarily the dredging efforts and briefly

addresses other Corps of Engineers activities as well.

INTRODUCTION

In late March 1980, Mount St. Helens in southwest Washington State beg n

exhibiting earthquakes and minor steam and ash ejections, signaling a new era

of activity for the 123-year dormant volcano. Minor eruptions continued,

becoming larger as the weeks passed, resulting in a massive and explosive

eruption on Sunday morning, 18 May 1980. On that morning, two magnitude 51

Richter scale earthquakes occurred at 8:32 and 8:34 Pacific Daylight Time.'

The upper north flank of the mountain, which for a few days previously had!

bulged outward as much as five feet per day, gave way in an immense landslide, instantaneously releasing the pressure of a plug of gas-charged magma

that had risen within the crust below the volcano.

The eruption and blast disgorged an estimated four billion cubic yards! of

material from the top and center of the mountain, lowering its height by more

than 360 meters and forming a huge crater more than a 1.6 kilometers in diameter. It is estimated that approximately one quarter of the three billionl

cubic meters of material emerging from the mountain was dispersed into the!

atmosphere in the form of volcanic asb which settled in varying thicknesses

over hundreds of square miles to t--e northeast of the volcano. As much as

five centimeters was recorded in home communities in eastern Washington,

with thicknesses of I to 4 millimeters recorded in communities in Idaho,

Montana, and Wyoming. Figu .s I and 2 show Mount St. Helens before and

after the eruption.

367
Figure 1. Mount St. Helens and Spirit Lake before eruption

Figure 2. Mount St. Helens and Spirit Lake after eruption

368

4
As shown on Figure 3, the blast and resultant mud and pyroclastic flows

from the mountain's north side impacted the river basins of the Toutle,

Cowlitz, and Columbia Rivers. It is estiMated that approximately 3.2 billion

cubic meters of material settled in the upper 22 kilometers of the north fork

of the Toutle River, with a much smaller but still staggering 45 million

cubic meters settling in the upper reaches of the south fork of the Toutle

River. Mudflows in the following 24 hours, buoyed by melting mountain ice

and waters displaced from upper Toutle River channels, carried more than 38

million cubic meters of material into 34 kilometers of the Cowlitz River from

the mouth af the Toutle downstream, and deposited an additional 35 million

cubic meters in the Columbia River, upstream and downstream of the mouth of

the Cowlitz River near Longview. Those flows and volumes occurred in less

than a 24-hour period after the eruption. The Toutle and Cowlitz rivers

experienced two successive flood crests, the second crest occurring early on

19 May. At Castle Rock, it equaled a 250-year frequency flood. This flow

came from less than one fourth of the river basin's drainage area. Columbia

River infill took place between the hours of midnight and 5:00 a.m. on

19 May.

It is difficult to conceive of the tremendous volumes of material moving

in the river channels in so shortsa period of time. Flood profiles did not

exceed previous record flood levels in the Cowlitz and Columbia Rivers,

although they did approach major flood levels in tte Cowlitz River above

Longview and Kelso. Mudflows in the lower river did not build up at any one

location, but resulted in uniform layers of sand and gravel and other debris

deposits throughout the floodplain of the lower Toutle and lower Cowlitz

River valleys. Instead of the normally stained high-water marks as

experienced in rainfall floods, almost everywhere the water flowed in the

lower Cowlitz and Toutle rivers a dense layer of ash, sand, and gravel was

left. What occurred could be likened to a large volume of material, with the

consistency of "pancake batter," flowing at a high rate of speed along river

valley floors and simply leveling out and settling as the flows continued

downstream. Figures 4 and 5 show results of physical analysis of the mudflow

materials deposited in the Cowlitz and Columbia Rivers. Figures 6 and I show

the Toutle and Cowlitz River valleys after the floods.

WATER QUALITY IMPACTS

On the day of the eruption the massive mudflow into the North Fork and

South Fork of the Toutle River not only resulted in enormous sediment transport, but also, because of the pyrocla.:tic nature of much of the mudflow

material, water temperatures in the river raised drastically. On 19 May it

has been established that at the mouth of the Toutle Fiver where it enters

the Cowlitz River approximately 64 kilometers from the base of the mountain,

temperatures were in the neighborhood of the 32 and 33* centigrade. Turbidity

levels were nearly immeasureable; and measured suspended sediments peaked at

between 1-1/2 and 2 million miligrams per liter for a peak river flow of

approximately 1,700 cubic meters per second. On the following day, 20 May,

temperatures and suspended sediment loads tapered off, but nonetheless,

suspended sediment loads were well above 1 million miligrams per liter with

corresponding river flows of only 60 or 90 cubic meters per second. For

those two days there was more than 150 million tons of sediment passing from

the Toutle River into the Cowlitz River. Turbidity levels at the Longview

369
INITIL ERUTIONAREA DEVASTATED

INITIAL ERUPTION

Figure 3. Area I affcte EN byIN erptonofMunS.eln

370
44 4 Ii WiS CU

f, ITL

S-..

h I

- - ( - t -- rT T+ --. T- .4 :-4 - - -F !: T - - ---

i I "t+ ,k - ,+ + + . .

I'll f 2-0 MY • I silty SMI. (Sa... •).. 5!T.+-. L

17. .2 20 M~ 4404 0-d SILT (ML) - 'MI TICcu. as.

8.5 220 PI.Y 6OCý -"No~ >

G.A.ATIOt4 CURVES N9 .7 J- .,to, (30-3- 9)

Figure 4. Physical analysis, Cowlitz River

- t+-!

7

COM A 6 7 4 ' A n+, • - . +

C I? ý .. -.. . . " . f2. . . 0 .

-.. -r... -F-_+ -.-.-... --. ~ -- : -. -- - : .----

,O7 C E, -- ,-: 25.++-- -

Figur 5. Physical ansis C••- - R-ive -+ r .----.. ' ., ++.:u;+.. 71

S.. r .. .. . . .. . . + .,

0 SA9O '7) - +i 7 ...... . . ..11 4.. . I CIII .4.10 C.... AN .. ?' _

. G.. AOA+ T' O CURVIS+ IPO ...... . 20 2 ... + I ... IS--M

Figure 5. Physical analysis," Colu bia River

+,,, o, ,,'+ •+ :,. ,,, .i,.+- L.,. '" °''++371<+ -
water system plant, 24 kilometers downstream from the mouth of the Toutle

River,on 19 May were above 50,000 JTU's (almost i measureable). Water

temperatures on 19 May in the Cowlitz River at that location were also above

300 centigrade. Water temperatures for the next few days quickly reduced to

near normal levels of 8 to 150 centigrade, while suspended sediment loads

reduced from 10 to 20 thousand milligrams per liter for the first week and

gradually continued at fairly significant rates of from 6 to 15 thousand

milligrams per liter with isolated peaks of 30 or more thousand milligrams per

liter in following months. During infrequent rainstorms over the winter of

1980-1981, suspended sediment concentrations would increase significantly for

several days and turbidity readings would often approach 7 to 8 thousand

JTU's. During the summer of 1981, one year after the eruption, suspended

sediment readings reached low points of 15 to 20 milligrams per liter with

corresponding turbidity readings of near normal 5 to 7 JTU's. With the

exception of the first few days after the eruption in May of 1980, dissolved

oxygen readings were generally near the normal in a range of 8 to 12 wliigrams per liter. There qre no readings recorded for the first few days after

the eruption for dissolved oxygen levels.

FISHERIES IMPACT

The initial high temperatures caused in the Toutle and lower Cowlltz

Rivers by the eruption of 18 May immediately resulted in the killing of

essentially all fisheries resources in those portions of the Toutle and

Cowlitz Rivers impacted. Temperature readings of above 30 - 330 centigrade

were recorded the day after the eruption in the lower Toutle River and near

that figure in the lower Cowlitz River. Although those temperatures subsided rapidly in following days, the damage had already been done and fishery

resources were essentially eliminated. Because of the continued high levels

of sediment transport and turbidity readings experienced throughout the

summer of 1980 and the fall of 1981, fisheries interests were fearful about

the survial of fish attempting to return up these tributaries from the ocean

and the Columbia River. However, in July of 1980, only six weeks after the

eruption, Washington State Game Department officials used electroshocking

techniques in the Green River, a tributary of the North Fork of the Toutle

River, to ascertain the potential existence of fishery stocks. To their

pleasant surprise, they encountered significant numbers of steelhead that

could only have originated from Columbia River waters in the intervening

period. This is especially significant because turbidity levels were still

in the neighborhood of many thousands JTU's and up until this time those

levels had been reported as potentially fatal to anadromous fish species.

Late in the summer and early fall of 1980, t'he fall chinook and coho run from

the ocean up the Columbia River also proved to be near record proportions and

the runs entered the Cowlitz and traversed to the Toutle River in large

numbers. So many of these fish returned to the hatchery sites on the Green

and Cowlitz Rivers that the Game Department opened a special season for gill

netters at the mouth of the Cowlitz in the fall of 1980 to harvest the excess

numbers of those fish. Again, turbidity levels were at significant levels in

the lower Cowlitz and Toutle river basins, but appeared to have no impact on

the returning trends for these anadromous fish. In the late fall of 1980 and

early winter of 1981, the traditional smelt run was observed in the Columbia

River. Since smelt, although being an anadromous type species, are not prone

372
V

Figure 6. Toutle River valley after high density flood

Figure 7. Cowlitz River valley after eruptive floods (note

how mobile homes floated on mudflow)

373
""mil

to return to their exact place of birth, but rather will often enter into any

suitable stream to their liking, it was not anticipated that they would

return in large numbers to the Cowlitzý River as experienced normally on a

annual basis. However, in 1981, the smelt run was near record proportions and

a substantial portion of the entire run spawned in the Cowlitz River.

Commercial and recreational dipping was allowed at high levels for many weeks

in the lower Cowlitz River, in the presence of the, large number of dredge

plant working in these rivers. The National Marine Fisheries Service

accomplished a series of tows with their nets to determine if smelt eggs were

present, and whether eggs had hatched into larva since smelt larva do not

stay in the gravel, but drift freely after they hatch. National Marine

Fisheries Service in all tows observed the existence of both fertile smelt

eggs and live larva in large numbers.

The apparent lack of impacts on the anadromous fish species in the Toutle

and Cowlitz Rivers was a pleasant surprise for nearly all concerned. It

demonstrated that those species generally could cope with the high suspended

sediment ar. turbidity levels and the Ilarge number of dredging plant working

in the stream 24 hours a day, 7 days a week, without significant impairment.

FLOOD CO TROL IMPACT

Thirty-four kilometers of the Cowlitz River from the mouth of the Toutle

River downstream to the Columbia River were impacted with virtual elimination

of natural channel capacities. Figure 8 illustrates profiles of the lower

Cowlitz River before and after the mudflows. At the time of the eruption,

lower Cowlitz River flows were about 170 cubic meters per second with a gage

height of 9 meters. Those river flows after the mudflows on 18 and 19 Mby

were essentially at bank-full capacity with a gage of 13 meters (4-meter

rise), In addition, because mudflow materials remained in essentially all areas inundated, valley storage capacities for normal floods were severely

reduced. The communities of Lexington and Castle Rock as well as the larger

communities of Kelso and Longview (total population of about 60,000) were

left virtually without flood protection.

The Cowlitz River channel, from about 2.5 meters immediately above the

mouth of the Toutle River downstream to the Columbia River, infilled with

depths of material varying from 1.5 to 5 meters. The lower reaches of

tributary streams of the Cowlitz River were also infilled and blocked off by

mudflow material. Drainage ditch outlets, storm sewer outlets, headwall

structures, etc., were not only plugged but covered up with several feet of

material. An immediate and unusual flood impact caused by the mudflow

material was local flooding in many of the tributary stream drainage areas

during the summer l-w flow periods. 'As a result of their entrances being

dammed, residual flows from creeks and streams becked up and flooded

buildings, roads, and other developed arcas.

374
70F- f j 1 '-

IO

40'. cis. Ml_ B

-0POPRE fLOOD FLOO

-J U,

8 7 _ , 3 Z7 1 Z3 25

(8.05 K) RIVER MILE (40.23 K)

FIGURE 4 COWLITZ RIVER

Figure 8. Flood control restoration

Lower Cowlitz

Approximately 8.5 million Lubic meters of infill was removed by pipeline

dredges from the lower Cowlitz River. (R.K. 0 to 14.5) by November 1980. Work

in the lower Cowlitz River by dredges was phased out over the months of

February, March, and April. Fifteen million cubic meters total was removed

from the lower Cowlitz.

With 85 percent of the flood-carrying capacity eliminared by mudflow

deposits, it was clear that channel excavation was required at an early date.

The lower nine miles (14.5 kilometers) of the Cowlitz River passes through an

urban area where the majority of the communities are protected by flood

control levees. A lack of adequate disposal areas, or the extensive work

required to prepare them, led to a decision that all work in the lower nine

miles would be accomplished by pipeline dredges which could pump dredged

materials some distances, contracted on an hourly rental basis. Dredging was started in this reach of the river with (letter) contracts to the two firms

owning the only three 500-millimeter pipeline dredges available on the West

Coast. Subsequent contracts for dredges use(. '.ong this reach were on the

basis of competitive bids for specified minirn size dredges.

Disposal areas were sparse and -_aquently several hundred to several

thousand meters from the river channel. Recognizing the threat of flooding

from the flood season beginning in November, landowners were extremely

cooperative in providing the use of their lands for disposal of material at

no cost to the Government.

375

/L7
S//

/~/'

Early dredging activities in the lower three kilometers of the Cowlitz

River indicated that sediment transport and deposition were continuing at a

very high rate and that progress at moving upriver would be extremely timeconsuming. The major threat from flooding was in the reach of the river

above kilometer 8. Consequently, two 500-millimeter dredges, the ART RIEDEL

and HERB ANDERSEN, were taken overland from river kilometer 2.5 to kilometer

10 in order to accelerate arrival of dredging capacity in the needed area

(Figure 9). Disassembly and reassembly methods for portable dredges, if

normally followed, would require at least six weeks to accomplish. The owner,

however, after extensive coordination with local police, utility companies,

and officials, suggested moving the dredges in essentially one piece. The

moves were accomplished in one day with virtually hundreds of workmen, both

public and private, involved. This spirit of cooperation and assistance by

the communities and contractors was evident throughout the recovery effort

and contributed significantly to its overall success.

The ART REIDEL was out of service a total of seven days, the HERB

ANDERSON for fifteen days. The heavy hauling equipment used to move the 350-

and 500-ton load required 5,8 and 72 wheels, respectively. Figure 10 shows the

ART REIDEL reassembled and in operation on the Cowlitz River.

Upper Cowlitz

On the reach of the Cowlitz from kilometer 15 to 36, the mudflow had

deposited material over the majority of the valley floor for a width of about

two kilometers. Landowners in this reach were willing to receive fill

material on their lands to raise the area above flood level. It was

determined that contracts for excavating the channel in this reach be on a

fixed price basis by measurement of material in the disposal area. An option

for establishing' settlement mar..ers removed one of the concerns to bidders.

The river was broken into contr;'.;t sections of two to five kilometers so that

multiple contractors and maximumu resources could be devoted to the work, providing 'he best likelihood of completion by late 1980. Specifications for

the work in restoring the river channel were written for the opportunity of

not only dredging contractors, but also contractors more accustomed to road

building. Competition was keen with as many as 16 bids submitted on some

jobs.

By November, approximately 12 million cubic meters of material was

removed from the Cowlitz River between kilometers 15 and 36. By the time

work was phased out in the summer of 1981, a total of nearly 43 million cubic

meters had been removed from the entire Cowlitz River. A 1,400-cubic-metersper-second channel capacity was achieved earlier in December.

Disposal Area Treatment

During the early spring months of 1981, afte-r nearly a full year of

dredging of the Cowlitz and Columbia River and disposal of materials in

adjacent properties, a contract was awarded to a firm to dress up the disposal areas and fertilize and plant several types of grass seed in order to

control blowing sand. Since the disposal areas essentially consisted of sands

376
Figure)-9. Overland 4.Ove of ART RIEDEL

M" 

ýN
Figure 13. Highline on Cowlitz River

Figure 14. Draglines on Cowlit~z Ri-4-er

378
and gravels, it was anticipated that a grass crop would not grow to lush proportions, but would provide the minimuhi desired cover. Since the disposal areas

were mostly on private properties and were targeted for future developments of

some type or for borrow sites to sell the materials for commercial purposes, no

further treatment was contemplated.

NAVIGATION IMPACT

The Columbia River navigation channel from the mouth to Portland, Oreg.,

and Vancouver, Wash., is maintained at a 12-meter depth, 183-meter width.

The Cowlitz River enters the Columbia at river kilometer 52, and the

Willar-ýtte River, which serves the Portland Harbor area, enters the Columbia

at kj!'reter 160. The Columbia River serves primarily tug and barge and deep

draft vessel traffic with commerce in excess of 30 million tons per year in those

reaches. Prior to the eruption, a routinely maintained navigation channel

existed in the lower 6.5 kilometers of the Cowlitz River with dimensions of

2.5 by 46 meters.

Maintenance of the 12-meter channel requires annual dredging of about

3.8 million cubic meters of primarily clean sand materials. In-place density

of Columbia River sands is an average of 1,900 to 1,950 grams per liter.

This yardage is normally removed from shoal areas existing throughout the 167-

kilometer reach to the Portland area. Before the eruption, normal maintenance

of the Cowlitz River channel was accomplished on a periodic basis about once

every three years. Shoaling conditions usually required removal of only 115,000

to 190,000 cubic meters of gravelly sand materials.

As reported by the Columbia River Pilots Association, a deep draft vessel

traversed the Columbia River channel in the vicinity of River kilometer 52 in

an upstream direction without incident about 3:30 a.m. on 19 May. However,

at 5:30 a.m. on, 19 May another vessel progressing upstream ran hard aground

adjacent to the mouth of the Cowlitz River and had to be assisted off b- tugs

.later in the day. Hydrographic surveys were taken late that day after turbidity levels subsided enough to allow penetration of sonic fathometer signals.

They revealed that navigation depths in the Columbia River had been reduced

to 4.5 meters CRD (Low Water Datum) and navigation depths in the Cowlitz

River 4ere virtually nonexistent. Those depths essentially closed the

Columbia River channel upstream of Longview to deep draft vessel traffic.

Thirty-orne deep draft vessels were trapped upstream in the Portland-Vancouver

and Kalama harbors. An estimated 50 ships enroute to the area were forced to

stand off or were diverted to other ports. The cost to ports, the communities, and industry mounted to millions of dollars per day from the disrupt ir.

of deep draft vessel traffic in the Columbia River.

The major portion of the infill material in the Columbia River extended

from river kilometer 101 upstream to river kilometer 116. Figure 11 illustrates the distribution of the material in comparision with normal channel

depths. Based on surveys, approximately 10.7 million of the 34 million cubic

meters deposited in the river infilled the 12- by 183-meter navigation channel

in this reach.

379
:)3

* * -e

(101 K) 090 (11 K

T T

COLUMBIA RIVER

LONGITUDINAL PROFILE

RM 63-RM 72

Figure 11

NAVIGATION RESTORATION

Dredging

With preliminary data available early on 19 May after the grounding of

the KEOGH MASCOT, the U.S. Coast Guard closed the Columbia River to navigation at Longview. This information was transmitred to the Portland Districi

that day and the hopper dredge BIDDLE, working uct the mouth of the Columbia

River, was immediately ordered to proceed to th, area to begin emergency

dredging. The following day, the District's other two hopper dredges,

HARDING and PACIFIC, were recalled from Eureka, Calif., and Coos Bay, Oreg.,

respectively, to also begin work on the Columbia channel. The Port of

Portland's 760-millimeter pipeline dredge OREGON, working under contract for

the Corps in the vicinity of Astoria, Oreg., was ordered that day to mobilize

at the site as soon as possible.

Representatives of the U.S. Coast Guard, the Columbia River Pilots

Association, and the Corps of Engineers met on 19 May to develop plans for

restoration of the channel and resumption of river traffic. On 20 May the

plan for dredging was established as indicated in Figure 12. The hopper

dredge BIDDLE started work on the Columbia River channel on 20 May. The

BIDDLE started work on a 61-meter-wide emergency channel on the soutm edge of

the 183-meter-wide authorized channel.

380
The U.S. Coast Guard established a safety zone through the blockade

area. Deep draft vessels were restricted to passing through the area during

a 2-hour "window" on the daylight highi tide. This procedure provided the

raximum depth available for deep draft vessels and minimized the interruption

of dredging operations in the channel. Tug and barge traffic was ordered to

use that portion of the river south of the emergency channel.

Marine contractors on the West Coast and throughout the nation were canvassed by telephone to determine! the availability of large pipeline dredging

plant. The first result of this solicitation was that the two largest West

Coast dredging companies, General Construction Company of Seattle and Riedel

International of Portland, agreed to the latter firm entering into a contract

to furnish and operate equipment of both companies. Submission of preliminary cost and pricing data le#' to signing of the contract on 23 lay. Five large

pipeline dredges and two boosters would be furnished.

[ PHASE I HPEP DREDGES 200' OCANNEL- OUTH SEDE. CrT 34FT BELOW 0' 15 JUNE

PHASE n PiPLJNE DREDGE 300' O-A•HWL -N-TH SIDE. D TO 35 FT. BELOW 0' 30 JAE

PHASE 1 PIPELINE DREDGES 3W' CHANNEL- SOUTHX'I , DStE.:,DGE 7T0 38 FT BELOW ca 30 JAY

PHASE M PIPELINE DREDGES 300' OANNEL- NORTH WE DRIEDGE PROECT DEPTH 30 SEPT

SPHASE 3" PIPELNE DRED-GES SOUTH SIDE-rOEIGE FULL PROJECT OM,0ENS*N 30 NOV

PHASE M PPELIKE DREDES REST I AOEOUATE RIVER CROSS-SECT)ON SOUTH OF NAVIGATION CHANNEL 31 k*4A 1986

TO •M•ES-0 W TO 7MFT

67 W7 71IF

TYPICAL SECTION

COLUMBIA RIVER AT LONGVIEW

Figure 12. Timetable for restoration of Columbia River channel

381
Notice to proceed was immediately issued for mobilizing the dredges

MCCURDY and WASHINGTON from Puget Sound to the Longview area. Negotiations

continued to permit a definitized contract establishing rates for rental of

the fully operated dredge plant on an hourly rental basis, plus a fixed price

for mobilization and demobilization. Terms included in the contract provided

the Government the option to determine which equipment to use and how it would

be used on the project. Table I lists the dredges ultimately utilized for

Columbia River dredging.

Providing disposal areas required full cooperation between contractors,

local authorities, environmental interests, and various Federal, State, and

local agencies.

Because of the urgent nature of the emergency restoration, environmental

requirements were relaxed as iecessary by Federal and State natural resource

agencies, as long as all reasonable efforts to minimize impacts were

pursued.

The 1.7 million cubic meters of inmill in the channel project limits was

removed generally on schedule and an unrestricted navigation channel was open

to traffic by 30 November 1980. As of September 1981, a total of 18.3 million

cubic meters was removed from the Columbia River in order to restore both

navigation and hydraulic channel capacities.

Figures 13-16 show the various dredges and techniques used on the Cowlitz

and Columbia Rivers.

Rainier Fill

The Columbia River channel in the vicinity of Longview immediately downstream of the mouth of the Cowlitz River is naturally wider than required for

hydraulic passage of river flows. This condition, when coupled with extensive dredging normally conducted in the area to provide both the Federal

navigation channel and the mooring basins for the Port of Longview Industrial

facilities, created an area where shoaling was sccelerated because, of the

artificially deepened and widened channel. The deepening of the navigation

channel from 10.7 to 12.1 meters in the late 1960's and early 1970's along

this location included a plan for possible artificial narrowing by pile dikes

or fill. However, because of the concern of many local interests in the

area, the narrowing program was never accomplished. This fact, together with

the new condition of millions of cubic yards of mudflow infill immediately

upstream, raised the question of future ability to keep adequate navigation

depths consistent in the Port of Longview reach. Compounding the problem was

the probable large volumes of material to be transported into the area from

natural erosion of mudflow deposits in the Toutle River system.

Ttie services of a consultant familiar with marine channel design were

secured to assist Portland District personnel in the review of previous plans

for artificial works in the Columbia River channel area. A primary concern

was placement of dredged mudflow material in such a manner as to provide

long-term stability of the channel area. The plan proposed by the consultant

is illustrated as the Rainier Fill in Figure 17. Federal and State agencies

were apprised of the plan, and the landowner and the State of Oregon reached

an agreement on transfer of ownership. The latter was made possible by

382
TABLE 1. DREDGES USED TO RESTORE THE COLUMBIA RIVER AND

LOWER COWLITZ NAVIGATION CHANNEL

Pump Approximate

Name Size Horsepower Owner* Date Started CM Removed

Hopper Dredges

BIDDLE 2340 CM - A 20 May 80 1,530,000

HARDING 2064 CM - A 22 May 80 880,000

PACIFIC 382 CM - A 21 May 80 250,000

Pipeline Dredges

OREGON 762 MM 4985 B 22 May 80 4,800,000

MCCURDY 609 MM 3000 C 6 Jun 80 2,026,000

*WASHINGTON 609 MM 2900 D 7 Jun 80 2,100,000

OLLIE REIDEI, 686 MM 4200 C 7 Jun 80 3,400,000

TILLAMOCK 305 MM 600 E 15 May 81 17,500

MISSOURI 559 MM 2500 D 23 Jun 80 3,750,000

HUSKY 500 MM 2800 F 18 Jun 80 2,750,596

ART REIDEL 500 MM 1850 C 9 Jun 80 3,06C,000

H. ANDERSON 500 MM" 1850 C 19 Jun 80 2,000,000

CORNELIA B. 500 MM 1900 G i3 Sep 80 1,400,000

MR. GUS 406 MM 900 C 20 Aug 80 1,150,000

HOWARD 406 MM 2700 H 7 Sep 80 1,530,000

*Purchased by Western Pacific - renamed LOFCREN

Booster Pumps

SUPEi. BOOSTER 609 MM 3500 C 23 Sep 80

OREGON BOOSTER 762 MM 3000 B 30 Jul 80

SUPER SNOOSE 686 MM4 3600 C

#1 500 MM 1000 C 17 Aug FO

#2 500 MM 1500 C 10 Oct 80

#3 500 MM 2500 C 19 Oct 80

*Owners:

A - Portland District, Corps of Engineers

B - The Port of Portland, Portland, OR

C - Western Pacific Dredging Corp., Portland, OR

D - Gerneral Construction Co., Portland, OR

E - Newport Dredging Co., Portlatd, OR

F - Manson-Osberg Construction Co., Seattle, WA

G - Coast Aarine Construction Co., Portland, OR

H - Robers Dredge, Inc., La Crosse, WI

383
Figure 15. Large pipeline dredges on Columbia River. Mouth of

Cowlitz River in background

Figure 16. Hopper dredges BIDDLE, HARDING, and PACIFIC and

pipeline dredge OREGON on Columbia River

384
timely action on the part of the State of Oregon in establishing a fair value

for covered river bottom and by the riparian owner in agreeing to make

payment to the State and to replace his waterfront structures that would be

covered by the fill.

In addition to providing an area to dispose of approximately 4.6 million

cubic meters of mudflow material, it is anticipated that the engineering

of the plan will save millions of dollars in dredging costs in future years

by retarding the settling of eroding mudflow materials in the Federal channel

and Port of Longview mooring berths. It is expected the eroded mudflow

materials will tend to continue on through the narrowed river area and

deposit in areas less critical downstream. Dredging can then be scheduled on

a more efficient basis and where disposal areas are more readily available.

Beeman Plan

Initial dredging efforts were directed toward restoration of the 12.1- y

183-meter navigation channel. In late June 1980, however, as extensive

hydrographic surveys fully outlined the magnitude and location of the total

34 million cubic meters of infill, it was realized that excavation of the

channel project would not be enough to provide long-term stability. The

remaining mudflow materials in the river would continue to erode until the

river reestablished its hydraulic section during high flow periods.

This eroded material would result in intermittent and unpredictable

infill of the navigation channel downstream in future years. An engineering

study was initiated to determine the extent of additional dredging requiredý

to provide a nearly stable hydraulic channel as soon as possible. A consult •nt was utilized to study these problems and recommend solutions to District

personnel. Figure 17 illustrates the plan proposed by the consultant and

adopted by the Portland District.

It was anticipated that a total of 6.9 million cubic meters in additioA

to the 10.7 million already excavated from the channel would have to be

removed to provide a 90-percent reestablishment of the hydraulic

section. The "90-percent" effort is all that was practical and recommended!

because restoration of the remaining 10 percent would not be cost-effective.

Removal volume to improve the hydraulic capacity would involve increasingly

greater volumes for each added percent of improvement. A contract for

$10,386,000 was awarded in January 1981 for dredging of an additional 4.6

million cubic meters. This would supplement continued excavation by the Port

of Portland's dredge OREGON to provide the stable hydraulic section. This

project will be complete by June 1982.

385
(116 K)

WASHINGTON V

0 OREGON

"69

(107.8 K) WASHINGON

671

Figure 17. Ranier Fill plan proposed by consultant

Ina addition to the Rainier Fill and the additional hydraulic channel

excavation as described above, measures were also considered to minimize

future impacts of erosion of materials from the Toutle and Covlitz River

valleys and their transport into the Columbia River, resulting in possible

disruption of navigation traffic. As part of the dredging operation

accomplished in the first year, a sump was excavated at the mouth of the

Cowlitz River to intercept material being transported down the Cowlitz. The

purpose of the suap is to provide a location for a large dredge to remove the

mareria'.s trror to their reaching the Columbia River channel. The sump

currently being utilized is Thown in Figure 18. Removal of up to 1.5 million

cubic meters of additional material from the sump area was also provided as

part of the contract discussed above. The material removed from the sump is

being placed in a disposal area known as the Collins Estate. The Collins

Estate consists of a privately ow~ned large acreagn' of land t.hat includes

considerable wetland areas. The Portland District has diked off a portion of

the site and widll expand it only as necessary in future years to minimize

impacts to the surrounding wildlife habitat and wetland area.

386

S....:" ," I
NkN (U

L: 7

387
OTHER CORPS ACTIVITIES

In addition to the massive dredging program described in the previous

paragraphs to restore navigation channel depths and flood control protection

levels, the Corps of Engineers utilized other measures in an attempt to restore

channel capacities in the upper reaches of the Cowlitz and Toutle Rivers and

to control future erosion of the mudflows in the Toutle River basin. In this

manner, sediment transport into the Cowlitz and Columbia Rivers in future years

could be minimized. In the Toutle River, contracts were let to remove sediments

in the river channel and slope the banks of the mudf lows in an attempt to

confine the river channel to one location and retard erosion. In addition,

large debris-control structures or dams were constructed on the North Fork of

the Toutle near the base of the 22.5-kilometer-long mudflow from the mountain

and on the South Fork of the Toutle a few kilometers above its junction with

the North Fork. The debris structure on the North Fork consisted of a rock

fill nearly 2.4 kilometers in length and about 11.5 meters in height. The

South Fork structure was much smaller, being only approximately 152 meters in

length and 8.5 meters in height. Both of these structures were designed for

the purpose of trapping eroding.mudflow deposits upstream. Then the deposits

could be removed by excavation contracts in the following months and years and

deposited nearby, thereby preventing them from being transported downstream to

cause more significant damage to populated areas. Figure 19 shows a mudflow.

Levees around Castle Rock, the Lexington area, Kelso, and Longview were

also improved, heightened, strengthened, and lengthened t,. provide full 500-

year coverage under the channel conditions existing after the winter of

1980-1981. These levees were also protected with rock riprap throughout

nearly their entire lengths to provide a long lasting and substantial degree of

protection in the near future years. A short-term measure, which was accomplished during the summer of 1980, immediately after the eruption, consisted

of the purchase of storage space in a private power company flood control

reservoir on the upper Cowlitz River to reduce the impact of winter storms

during the first winter of 1980 to 1981. Purchase of this storage was highly

successful in that a large flood occurring during the 1980 Christmas holiday

was stored in its entirety in the Cowlitz River with only the Toutle providing inflow into the Cowlitz River from kilometer 37 downstream. Flows of

1,360 centimeters per second were still experienced in the Cowlitz River downstream from Castle Rock from the Toutle River contribution to this rainstorm.

Several fairly large lakes were formed during the sumr and fall of

1980 as a result of the large mudflow immediately adjacent to the mountain in

the North Fork of the Toutle River valley. As this mudflow deposited depths of

61 to 183 meters of material in the 22.5 kilometers of the upper Toutle River

valley, it closed off the entrance to many side canyons and tributary

streams. Lakes were formed in the pockets at the bottom of those canyons

(Figure 20). Several of these lakes were substantial in size as they developed

and posed serious threats to sudden and catastrophic overtopping of the mudflow

dike with possible disastrous consequences of this sudden rush of water and

sediments downstream. One lake reached overtopping levels in the late summer

of 1980, and an artificial channel was constructed to control its outlet. Two

other large lakes foimed throughout the winter of 1980-1981 and were predicted

388
7 ".97 - -

Figure 19. Mount St. Helens and mudflow in foreground

e.'.,-

Fiur 20 Lakes$ freby mdlr. dk cos aly

-a389
at the current rate of progress to overtop in the winter of 1981-1982. During

the slimmer of 1981, contracts were let to provide stable outlet channels to

those lakes so that they could be drainied under ccntrolled conditions and their

levels stabili.ed for the long-term future.

ENVIRONMENTAL IMPACT STATEMENT

Immediately after the eruption, the Portland District staff began

preparation of an Environmental Impact Statement (EIS) for the Mount St.

Helena recovery operations. This was to provide the public, Federal, and

State agencies an opportunity to review the alternatives considered and

probable impacts to the environment from actions under way or proposed. A

preliminary draft EIS was completed on 25 July 1980, and was sent to interested

Federal, State, and locai agencies for review. The final draft EIS was

sub,.itted to the Environmental Protection Agency on 19 Sept. 1980. The time

frame for production of the initial draft was only 20 days; therefore, many

procedural steps were abbreviated. Time did not permit a detailed and

in-depth review of each topic discussed. Tha EIS will be supplemented in the

future with updated information clarifying current options or new

alternatiyes as conditions develop.

In addition to the EIS, early plan formulation for the restoration effort

included an environmental task force of principal Federal, State, and local

agencies. The task force continues to meet periodically to review current

programs and future plans. The Corps af Engineers is attempting to accomplish the recovery work with strong corgideration of recommended environmental

protective measures proposed by the task force.

390
AD P 0024 13

THE WATER QUALITY PRESERVATION MEASURES IN LAKE BIWA

M. Shirahase, Assistant Chief

Water Administration Department

Shiga Prefecture

LAKE BIWA IN OUTLINE

With a surface area -f 673.90 square kilometers, Lake Biwa, the largest

lake in Japan, occupies about one-sixth of the total area of Shiga Prefecturt

in the Kinki District of Western Japan.

Other geographical data concerning the lake are as follows:

Length (north to south) 63.49 in

Maximum width (east to west) 22.80 .a

Overall coastline 235.20 km

Altitude (above sea level) 85.614 a

Maximum deptn 103.58 m

Average depth 41.20 m

Volume of water stored 27.500 million w

The lake bottlenecks at the mouth of the Yasu F ver (Figure 1). At this

narrowest part of the lake, Biwa-ko O-hashi (Grand .te Biwa Bridge) is constructed, bridging a span ot 1.35 km. Geographically, this bridge d.vides

the lake intc two parts, the northern part which is the primary lake basin

and the southern part which is the secondary lake basin. The average depth

of the northern basin is around 41 m, while that of the southern basin is only

4 m. This difference in shane between the two lake basins causes striking

contrasts in terms of water quality, varieties of aquatic life, and all other

aspects concerned.

Lake Biwa's ample supply of water is utilized ior agricultural, indltstrial, and household purposes. The lake itsolf provides good finting grounds

and is a valuable recreation center. Often called the -'ater-jar for the

Kinki area" the la':e plays a vital role in supplying water for the 13 million

people living and working in the Kyoto-Osaka-Kobe metropolitan district.

Improvement of the lake's water quality and other environmental protection issues are among the key current considerations in the prefecture's

administrative policy. Concomitant with Japan's high economic growth, which

began around 1960; the population increased sharply and industrial and agricultural activities became increasingly brisk. Regrettably, the pollution

load for public water areas showed a corresponding substantial increase. Lake

391
Kink, District

Hyogo " Prof. Sh

Prof, ref.

1ý1ýOsaka M~ Me

e Prof. Shiga Prefecture '".

~Prof.)

Wakayarna.,.-

,/1, h,

/Southern

basin YM ýi

Q' Sets River

Figure ,. S..,ga Prefecture showing Lake Biwa

Biwa became so contaminated that, in 1969, Shiga Prefecture instituted a

pollution control ordinance of its own to regulate the amount of vastewater

from factories and other bitinesI establishments.

As envirouoental pollution subsequently became a grave social prnbles

threatening to damage the health and living environment of the citizens on a

nationwide scale, the national government passed the Water Pollution Control

Law in 1971. In order to strengthen the working of this 1&4, in 1972 the

prefecture instituted still another ordinance. In 1973, this new prefectural

ordinance was totalty auserded to include more stringent regulations against

water pollution.

392
WATER QUALITY OF LAKE BIWA

- The national government's Basic Law for Environmental Pollution Control

provides for desirable environmental quality standards to be maintained to

protect the heaith and living environment of the citizens against air pollution, water contamination, and other environmental disruptions. For the

purposes of this law, several area types are provided for application to individual water areas covered. As for Lake Biwa and the Seta River, specific

envircamen'al quality standards were made public by the 1972 notification of

the Environment Agency, which applied the area types AA(a) and AA(c) to the

northern basin and the southern basin, respectively, and the area type A(a)

to the Seta River. (For drinking water, AA represents the top rating and A

the second rating.)

in order to help promote the attainment of these standards, a study has

been under way since fiscal year 1972 at nine fixed monitoring points specifically designated for this purpose (four in the northern basin, another four

in the southern basin, and one in the Seta River). Results of the study on

water qualit7 conducted in fiscal year 1979 showed that the environmental

standards for protecting the health of the citizens (comprised of nine items

relative to toxic substances) were met at each monitoring point. With regard

to the conditions of the living environment, it was found that the AA standards un DO (dissolved oxygen) were almost met at each monitoring point,

while the standards on COD (chemical oxygen demand) were yet to be attained

(Figure 2).('On the other hand, the pH (potential of hydrogen) level exceeded

8.5 when thO activity of phytoplankton was very brisk, indicating that the

"lake's water was weakly alkaline.

The capacity of the southern basin is rather small (200million tons as

compared with the 27,300 million tons capacity of the northern basin), and

there are a large number of factories and other business establishments surrounding the basin. Consequently, the population denfity and pollution load

per ui... are much higher and the water quality of the southern basin is, on

the whole, lower than that of the northern basin.

Since fiscal year 1966 the prefecture has been conducting a study of

Lake Biwa's water quality with the assistance of the Construction Ministry's

Regional Construction Bureau for the Kinki District at 48 fixed monitoring

points to obtain basic data for protecting the lake from further pollution.

According to this study, the water pollution of Lake Biwa had become progressively worse by degrees until about 1971 and 1972, after which the situation

began to improve slight'y for some time thereafter and then remained at almost

the same level until 1976.

However, in late May and enrly June of 1977, an abnormally large number

of plankton, predominantly Uroglena, appeared. These plankton were found

growing in a considerably large portion of Lake Biwa. This uas an indication

that the lake was tending toward eutrophication, and aheut to enter .a new

phase. As feared, a freshwater red tide broke out in 1978-1981.

WATER QUALITY PRESERVATION MEASURES IN LAKE BIWA

Lake Biwa is a closed water area that reflects the results of all human

activities within the prefecture. Accordingly, in formullating a long-range

393
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Figure 2. Environmental quality monitoring for

Lake Biwa (Continued)

394

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395
prefectural policy, top priority should be given to comprehensive water conservation measures covering the lake and the inflowing river.

It is said that eutrophication is caused by such substances as nitrogen,

phosphorus, vitamins, iron, maganese, an' cobalt. Nitrogen and phosphorus,

among others, are said to have a decisive influence. For this reason, and

after receiving a report from the Prefectural Council on Water Quality, an

Ordinance concerning the Prevention of the Eutrophication of Shiga Prefecture's Lake Biwa (appended to this paper) was established in October 1979 to

regulate these two substances. This ordinance is supported by a consensus of

the local inhabitants. Chapter 3 of this ordinance, Prohibition of the Use

and Sale of Household Use Phosphate Detergents, is especially important.

However, for water quality preservation in Lake Biwa, not only is the

regulation of nitrogen and phosphorus needed, but also the promotion C.f the

improvement works concerned with water quality in the Lake is essential, as

Chapter 1 of this ordinance provides. The representative water quality improvement works are dredging contaminated bottom sediment and sewage treatment

of wastewater. These works have been promoted in accordance with the Lake

Biwa Comprehensive Development Project which began in 1972. About I million

3

cubic meters of bottom sediment is planned to be dredged, of which 50.000 m

of bottom seditnent has already been dredged. However, problems stiJl1 exist

concerning dredging: the increasing cost of water treatment, the lack of

land for sediment managemen, and the destruction of the biological system.

Therefore, contaminated bot om sediment dredging works should he promoted

positively to overcome these problems.

396
ORDINANCE CONCERNING THE PREVENTION OF

THE EUTROPHICATION OF SHIGA PREFECTURE'S LAKE BIWA

(Ocwb~w 17, 1979 Si' gPm ectmal Owdnm 14 No. 37)

CONTENTS

Preamble

Chapter I GeneMl Provisions (Articles 1 - 6)

Chapter 2 Regulation of Exhaust Draina,. (Articles 7 - 16)

of Business-lndustrial Sites

Chapter 3 Prohibition of the Use and Sale (Articles 17 -20)

of Househdd Use Phosphate Detere nt3, etc.

Chapter 4 Restraint in the Dischar. of Nitroget and (Articles 21 - 24)

Phosphorus, etc.

Chapter 5 Miscellaneous Provisions (Articles 25 - 28)

chapter 6 Penel Provisions (Articles 29 - 2)

EfTective Date

397
Water, along, with the air and soil, is the foundation for the existence of

humaniind.

Lake Biwa, so copiously full of this water, as Japan's biges lake, even now

while challengng us with a breat task, brings fort, limitless blessings.

Remntly. due to factors such as the rapid ,1evelop-'zzt. of urbanization,

Lake Biwa is faced with deterioration -f its waterr quality, particularly the

abnormal situation of progressive eutrophication. Moreover, this is aot due to

the working of nature in Lake Biwa but has been caused by the daily living and

,-vmmerciai production activities of the inhabit"nts around Lake Biwa.

It is unforgivable for our generation to p.llute Lake Biwa.which has sustained various human activities continuously from the time of unrecorded

history.

Since water is a finite resource, Lake Biwa, surely the source of life of the

people who shar its benefits, is our great spiritual sustenance. We must without

fail, by surmounting numerous difficulties, establish a new coexistent relationship between thi water and humakind.

Particularly now, it is essential that we once more critically reconsider our

lifestyle which has come to pursue things like prosperity and convenience,

reflecting together upon Lake Biwa's multifaceted w~irth and the people's way

of lite and, with a bold and determined spirit, develop a comprehensive policy

for conserving Lake Biwa's environment.

The people of our prefecture who live together with Lake Biwa, loving it

azd being grateful for its benefits, awakened to a sense o" consciousness about

envirnmental conservation, now have passionatciy come to detvlop a creative

cot v'rvaon movement.

We white developing then buds of self-reliance and cooperation, to clarify

the revs xtive duties of the prefecture, cities, towns and villages, and the prefectural citizens and business people, and to protect Lake Biwa by working

together as a single group, resolving that we will bequeath a beautiful Lake Biwa

to future generations, as a first step, enact this law t j prevent the eutrophication

of Lake Biwa.

CHAPTER 1 GENERAL PROVISIONS

Article I

This ordinance, relating to prevention of Eutrophication of Lake Biwa, by

carifying the respective duties of the prefecture, cities, towns and villages, and

the citizens of the prefecture as well as the business people, and by devising

means for controlling effluents, and other measures, has as its purpose the

planning of the conservation of Lake Biwa's Cnvirnment.

393
(Dermilaions)

Article 2

1. In this ordinance "Lake Biwa" means the -Lake Biwa" to which the regulations of the Rivers Act (1964, Law No. 167) apply, as well as that portion

of the *Yodo River" of the Rivers Act which lies within and upstream of the

Setagawa Watergate.

2. In this ordinance "Eutrophication" means a phenomena of progressiely

worsening water quality in an enclosed water area, caused by the profligata

flourishing of algae and other aquatic plant Life due to inflow into the enclosed

water area of nitrogen or phosphorus containing substances (hereafter such

substances are called "N/P Substances").

3. In this ordinance a "Designated Facility" means any facility, set up at a

factory or business establishment, that discharges N/P Substance-containing

sewage water or any other N[P Substance-containing sewage fluid (hereafter such

sewage water or fluid is called "N/P Waste lqtr-"i) and is designated by regulation uader this ordinance.

4. In this ordinance "Public Use Water Areas" has the meaning defined by

Article 2, paragraph I of the Water Pollution Control Act (1970, Law No. 138).

5. In this ordinance "House hold Use Phlosphate Detergent" means a synthetic

detergent as defined by the Household Products Quality Labelling Act (1962,

Law No. 1,04). that in accordance with thc regulatiorm based on Article 3 o'

the sme law is required to be labelled as containing phosphate as an ingredient.

(Reqponsibilites of the Prefectumr

Artice 3

I. The Prefecture shall establish and implement ja-z and comprehensive

measures concerning the prevention of the Eutrophication of Lake Biwa.

2. The Prefecture shall give all necesary tssistance, as well as guida. ce •nd

counsel, to the cities, towns and villages in connection with their .. -r: ,s for

/mrplet nrting the prevention of the Eutrophication of Lake Biwa.

(Responsibilities of the Cities, Towns and Vilages)

Article 4

The cities, towns and villages shall earnestly endeavor to implement measures

for preventing the Eutrophication of Lake Biwa wihich harmonize with the

Prefecture's implementing measures and conform to the actual conditions in

the relevant district.

(Respov,sibilities of the Prefectural Citizem)

Article 5

Prefectural citizens must, togeth,: with earnestly endavonng not to do

acts that will casue the Eutrophication of Lake Biwa, cooperate with the Prefectural and cities', towns' and villages' implementing measures for the prevention of it

399
(Responsibilities of Business People)

Airticle 6

1. Business people when conducting their business activities must, together

with devising measures necessary for the prevention of the Eutrophication of

Lake Biwa, cooperate with the Prefectural and cities', towns' and villages'

implementing measures for the pre:ention of it.

2. Business people must make the greatest efforts to prevent the Eutrophication of Lake Biwa and may not use the fact that they are not technically in

violation of this ordinance as an excuse for neglect in doing so.

CHAPTER 2 REGULATION OF EXHAUST DRAINAGE

OF BUSINESS-INDUSTRIAL SITES

(N/P Drinage Stdards)

Article 7

1. D-Ainage standards, in connection with nitrogen or phosphorous, which are

for water that has been discharged from a factory or a place ofbusiness that has

installed a Designated Facility (hereafter such a factory or place of business is

called a "Business-lndustxial Site") into a public Use Water Area (hereafter such

discharged water will be called -Exhaust Drainage") will be called N(P Dranage

Standards" and established by regulation.

2. The Governor shall, when establishing or amending the N(P Drainage

Standards, beforehand solicit the opinion of the Ship Prefecture Water Quality

Council.

(Report of the Installation of a Designated Facility)

Article 8

(The rest of this chapter, as well as Chapter 4, does not apply to those

districts which are by regulation determined to be basins of rivers not draining

into Lake Biwa.) Any person who diszharges water from a facory or place of

business within the Prefecture into a POilic Use Water Area must, when plarning

installation of a Designated Facility, report to the Governor, in accordance with

procedure established by regulation, the items listed under the foWowing

numbers.

(I) Full name or appellation and address. In the case of a legal person, the full

name of its representative.

(2) The name of the factory or place of business and its address.

(3) The type of Designated Facility.

(4) The construction details of the Designated Facility.

(5) The method of using the Designated Facility.

(6) The method of treating N/? Waste Liquid to be discharged from the

Designated Facility.

400
(7) The concentration of nitrogen and phosphorus in the Exhaust Drainage,

the quantity of Exhaust Drainage, and any other items established by

regulation.

(Interim Measures)

Article 9

When a certain type of facility has be,ýome a Designated Facility, among

those persons who have actually installed one (including those who are constructing one), all who are discharging or will discharge Exhaust Drainage within

the Prefecture must, within 30 days after the type of facility has become a De.

signated facility, report to the Governor, in accordance with procedure established by regulation, the numbered items of the previous Article.

(Report of Modifications in the Construction or the like of a Designated Facility)

Article 10

Those.who have submitted a report according to the regulations prescribed

under Article 8 or 9, must, before attempting to make modifications in any of

the reported items (4) - (7), so report to the Governor in accordance with procedure established by regulation.

(Order for Modification of Plans, etc.)

Article 11

The Governor may, within 60 days of receiving a report made under the

regulations of Article 8 or 10 of a Business-industrial Site whose Exhaust

Drainage he rinds does not meet the N/P Drainage Standards at the place where

the Exhaust Drainage is discharged (hereafter called "Discharge Outlet"), order

the reporting Ferson to alter his plans as appear in the report for the Designated

Facility's con=iriction details, method of use, or method of treating the N/P

Waste Liquid to be discharged, or to abandon his plans for the installation of

the Designated Facility reported under the reiations of Article 8.

(Restriction on Implementation)

Article 12

I. Those ',.. - have filed a report in accordance with the .-gulations of Article

8 or 10, during the 60 day period following the Governo:'s receipt of the report

must not respectively install the Designated Facility of the report or modify the

construction or method of using the Designated Facility or method of trenting

the N/P Waste Liquid discharged from it.

2- The Governor, when he rinds that the cont"nts of the items in a report

made in accordance with Article 8 or 10 are acc-ptable, may shorten the 60 day

waiting period provided by the previous pargnrph&

(Report of Change o(Narme, etc.)

Article 13

401
When a person has filed a report in accordance with the regulations of

Article 8 or 9, if any of the items mentioned in Article 8, numbers I and 2 has

changed, or the use of the Designated Facility of the report has been discon.-

tinued, a report to that effect, in accordance with procedure established by

regulation, must be made to the Governor within 30 days from the chap.

(Succession)

Article 14

I. Any person who succeeds to the rights in, or rents, a Designated Facility

from a person who has made a report concerning the facility in accordance with

the regulations of Article 8 or 9, will be treated as succeeding to the status of

the person who made the report.

2. When, following the making of a report concerning a Designated Facility

in accordance with the regulations of Article 8 or 9, there is a tranf by inheritance or, in the case of legal persons, a merger, the heir, or suviving or

succeeding legal person, will be treated as succeeding to the status of the person

who made the report.

3. A person who, in accordance with either of the previous two pragraphs,

succeeds to the status of a person who made a report in accordance with Article

8 or 9 must, within 30 days of succession, report that fact to the Govrinor.

(Limits on Discharge of Exhaust Driage•)

Article IS

1. A person who discharges Exhaust Drainage within the Prefecture must not

discharge Exhaust Drainage that does not meet the NIP" Drainage Standards at

the Discharge Outlet of his Businessndustrial Site.

2. When a certain type of facility becomes a Designated Facility, with respect

to water discharged from a Business-Industrial Site of a person who has actually

installed one(including those who are constructing one), the previous paragraph's

provisions will not be applied for a period of one year from the date the facility

became a Designated Facility (or, wk-n the facility is governed by regulations

for unavoidable circumstances justify ng an extension of this period, a period

determined by regulation for such a facility). However, if at the time the type

of facility in question becomes a Designated Facility the Business-ladustial Site

already has some other Designated Facility, the above grace period will not

apply.

(Improvement Orders, etc.)

Article 16

1. When theGovernor 7nds that there is a risk that a person who isdischarging

Exhaust Drainage within !he Prefecture is or will discharge Exhas Drainage

that does not meet the N/P D1'z.-.ge Standards at the Discharge Outlet of his

Business-industrial Site, the Governor can both order that person to temporarily

r.it the use of the Designated Facility or halt the discharge of Exhaust Drainage

and order the improvement, within a specified time limit, of the Designated

402
Factfity's construction, method of use, or method of treating the N/P Waste

Liquid that isdischarged from the Designated Facility.

2. The provisions of Article 15 paragraph 2 correspondingly apply to orders

made in accordance with the provisions of the previous paragraphCHAPTER 3 PROHIBITION OF THE USE AND SALE OF

HOUSEHOLD USE PHOSPHATE DETERGENTS,

ETC.

(Prohiition of Use, etc.)

Article 17

1. (In this chapter "Prefectural Interior" mrs the entire Prefecture except

for certain areas excluded from this chapter's provisions by regulation, such as

basins of rivers not draining into Lake Biwa, etc..) No one may use Household

Use Phosphate Detergents within the Prefectural Interior.

2. No one may give Household Use Phosphate Detergents as a gift to a person

who has a home or dwelling place within the Prefectural Interior.

(Prohibition of Sales, etc.)

Article 18

1. Those who sell commodities as a business and others who, under whatever

name, receive a benefit from supplying commodities as a business (hereafter such

persons are called "Distributors-) must not sell or supply Household Use Phosphate Detergent wihin the Prefectural Interior. However, this resticnon sh-il mot

apply to sales or the supply of commodities to persons who promise that they

will not use the Household Use Phosphate Detergent within the Prefectural

Interior and furnish a written Request giving their name, address, the purpose

for purchasing or having it supplied, the amount, and any other items determined by regulation.

2. Distributors who sell or supply Household Use Phosphate Detergent to a

person who has made the promise of the exception provided in the previous

paragraph must preserve that person's written Request for one year from the

date of such sale or supply.

(Instructions)

Article 19

1. When he finds that a Distributor is selling or supplying Household Use

Phosphate Detergent in violation of the provisions of Asrt.c!e 18, paragraph 1,

the Governor can demand that the Distributor furnish a report of all necessary

information and sgive the Distributor any necessary instructions to obey that

paragraph's ,;Xrviions.

2. When a Distributor is not preserving the written Requests of Atticie 18,

paragraph 2, the Governor can demand that the Distributor furnish a report of

403
all necessary information and can give the ')istributor any necessay instxtiUuns

to preserve the written Requests.

(Orders to Take Action)

Article 20

When a Distributor who has received instructions in accowdiance with the

provisions of Article 19, paragraph I or 2, is selling or supplying Household

Use Phosphate Detergent without obeying those instructions, the Governor can

order the Distributor to remove the Household Use Phosphate Detergent from

display or do any other necessary acts.

CHAPTER 4 RESTRAINT IN THE DISCHARGE

OF NITROGEN AND PHOSPHORUS,

ETC.

(Proper Use of Fertilizer, etc.)

Article 21

(This chapter does not apply ic thcse districts which are by regulation

determined to be basins of rivers not draining into Lake Mwa.) People professionally engaged in agriculture within the Prefecture, in order to avoid

indiscriminately disc,,zgng , ccn-tin-- n," L N., Substzces in• Public Use

Water Armeas, must properly use fertilizer and control the use of agriculturaI

water.

(Proper Disposal of Domestic Animal Waste)

Article 22

People who professionally engage in animal husbandry within the Prefecture,

in order to avoid discharging domestic animal waste into Public Use Water Areas,

must, along with endeavoring to install a disposal facility for such wage, properly dispose of it by such method-t as soil restoration, etc..

(Miscellaneous Drainage Disposal)

Article 23

Everyone must try not to discharge indiscriminate amounts of food w-a e,

etc. in miscellaneous drainage into Public Use Water Areas.

(Guidance and Counsel)

Article 24

The Governor, with respect to the provisions of Articles 21 - 23, will give

the guidance and counsel necessary to accomplish thevtr gcals.

404

I II I I I I I IMII 
CHAPTER 5 MISCELLANEOUS PROVISIONS

(On-the.slte Inspections)

Article 25

I. The Governor, within the necessary limits for enforcing this Ordinance,

may have his staff enter and make inspections of Businessndustrial Sites and

Distributors' places of business, stores, warehouses, etc. and request reports of

data or explanations from the permns concerned.

2. Those who, under the provisions of the pe'vious paragraph, are authorized

by the Governor to make on-the-site inspettions must carny proof of their

identity and officisl capacity and present it to the persons concerned.

3. The authority under the provisions of paragraph I to make on-the-site

inspections must not be interpreted as permitting entries made for the purpose

of criminal investiptions.

Prefecal Aistance)

Artic; 26

1. The Prefecture, in order to contribute to the promotion of the insullation

and impromvrent of facilities, etc. for disposl of NtP Watge Liquid, must

endeavor to Ove assistance by financing, or acting as a go-between to obtain,

the necessary funds, and giving technical counsel, etc.

2. When carrying cut the measures of the previous paragraph, special consideration must be given to the situation of smanl and medium-sized enterprises.

(Monitoring Obliption)

Article 27

A person who has installed a Designated Facity must, in accordance with

provisions established by regulation, measr.re the condition of the water d.scharged form his Business-[ndustnal Site and ke a rcord of the results.

(Rulemaking Authority)

Article 23

The Governor may, by regulation, establish all necessary provisions for the

enfor:ement of this Ordinance.

CHAPTER 6 PENAL PROVISIONS

(Penalties)

Aztic;e 29

A person described by either of the two numbered ite-m beWow may be

pumshed by a fire of up to V 100,C.

(1) A person who has violated an order of the Governor issued in accordance

405
wth dw prioaosm of Artcle 11. Article 16, pargaph 1,or Article 20.

(2) A peson who has violated the provWtos of Article 1S, pmmpap. 1.

Artice30

A peron desaed by my of thw nunibred as.. below nay be punished

by a fine of up to V 5,000.

(1) A p non who has, with re t to th provisions of Aiclde S. 9, or 10,

failed to file a required report or filed a fain report.

(2) A pron who has violated the 60 dty w,,,aa period required by Article

12. paraap 1.

(3) A person who has refisd to aow, obstructed, or eanded an on.-h4ite

ntion provid fog by Article 25, paragph I or refused to make a

report of data or S" Iformao requested under the prov of that

paragrp.

Article 31

A parson who has filed to Me a report of changes required by Artice

13 or a report of swoedon a required by Article 14, paagraph 3, o wh has

fied a false report, my be punided by a (Low of up to V 30,00.

(Multiple Pemitias)

Actlek 32

When a pe-ow who Is the ropmem tsatv official of a eg prson or etmnployed as an t, emrploye, etc. of a-i.*e pemson of a leow Peso. has

violated any of the penal provwio s of Articles 29 - 31 in corumction wth the

other pe.r's or WeO persons busines, In additin to punishing the acWual

violator, the various flesm of thaw Aticles may also be mVpd on the othr

peron or Ietl perso whom the violator represents or is employed by.

(Effective Defte)

TMlt ordimmm's provison shall go into effect an a day, ot later than ow yew

after this Act's prontuiptio, determined by regulon.

406
WATER POLLUTION CONTROL PROJECTS

IN RIVERS AND LAKES IN JAPAN

Kanenobu Hagivara

Urban River Division, River Bureau

Ministry of Construction

TABLE I NUMBER AND TOTAL LENGTH OF RIVERS (1980)

Total

River length

basins Rivers (k.m)

Class A rivers 109 13,267 85,757*

Class B rivers 2,615 6,615 33,561

* Length administered by national government is 9,945 km

among total length.

407
TABLE 2 NUMBER OF SAMPL14G SITES FOR

WATER QUALITY tNViSTIGATION

IN CLASS A RIVERS*

Year Number of sampling sites

1969 142

1970 524

1971 662

1972 727

1973 746

1974 837

1975 874

1976 886

1977 915

1978 953

1979 979

1980 997

* Section administered by national

government.

408
Tb

TABLE 3 PERCENTAGE OF BOD ANNUAL MEAN VALUE

IN CLASS A RIVERS

Value ot BOD (ppm) 1978 (%) 1979 (%)

I under 25.9 28.4

1 - 2 39.4 40.7

2 - 3 15.3 14.3

3 - 5 9.7 8.2

5 - 8 4.7 3.6

8 - to 1.2 0.8

10 - 20 3.4 3.1

20 - 30 0.6 0.7,

30 - 50 0.3 0.1

50 - 100 0.1

100 over 0.1' 0.1

Total 100.0 100.0

Number of sampling sites 1978 876

1979 879

409
TABLE 4 CHANGE OF SOD ANNUAL KEAM VALUE IN CLASS A RIVERS

Number of

2 sanpl ing

3 pp. under 3 - 10 ppm 10 ppm over sites

1970 58.7 23.6 17.7 521

1971 59.6 24.2 16.2 661

1972 71.3 20.2 8.5 727

1973 72.6 20.0 7.4 746

1974 75.9 17.4 6.7 837

1975 82.3 12.7 5.0 874

1976 83.2 13.1 3.7 895

1977 81.6 13.7 4.7 852

1978 80.6 14.8 4.6 876

1979 83.4 12.6 4.0 879

410
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TABLE 6 THE YEAR'S WORST FIVE RIVERS IN BOD (CLASS A RIVER)

BOD annual

Number of mean value

Year Rank River sampling sites (ppm)

Yamato River 8 19.7

2 Ayase River 2 19.0

1978 3 Turumi River 4 13.8

4 Ibo River 6 7.7

5 Tama River 10 6.8

I Yamato River 8 13.9

2 Ayase River 2 13.4

1979 3 Turumi River 4 13.4

4 Ibo River 6 7.3

5 Tama River 10 6.1

412
TABLE 7 RATIO OF SAMPLES EXCEEDING WATER QUALITY STANDARD

FOR BOD IN CLASS A RIVERS

Water ,'uality Water 4uality

categories s;andard for BOD 1978 (%) 1979 (%)

AA l ppm 55 53

A 2 ppm 31 27

B 3 ppm 33 29

C 5 ppm 50 50

Dý 8 ppm 42 31

E 10 ppm 53 43

Total 36 32

Number of sampling sites 1978 889

1979 890

413
TABLE 8 RATIO OF SAMPLES EXCEEDING WATER QUALITY STANDARD

FOR BOD IN CLASS A RIVERS

(Classified by Region)

Number of

Region 1978 (%) 1979 (%) iampling sites, 1979

Hokkaido 6 5 63

Tohoku 33 27 120

Kanto 51 47 150

Hokuriku 22 21 70

Chubu 15 ii 89

Kinki 61 54 121

Chugoku 36 37 100

Shikoku 24 ?4 45

Kyushu 38 33 132

Total 36 32 890

414
TABLE 9 RATIO OF SAMPLES EXCEEDING WATER QUALITY STANDARDS

RELATING TO PROTECTION OF HUMAN HEALTH TO THE

TOTAL NUMBER OF SAMPLES TAKEN IN CLASS A RIVERS

Water quality

Substances standard 1978 (%) 1979 (%)

Cyanide N.D. 0 0

Alkylmercury N.D. 0 0

Organic P N.D. 0 0

Cadmium 0.01 ppm 0.10 0.05

Lead 0.01 ppm 0.05 0.01

Chromium VI 0.05 ppm 0 0

Arsenic 0.05 ppm 0.24 0.21

PCBs N.D. 0.10 0

Total Mercury 0.005* ppm 0 0

* Annual averages.

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416
TABLE 11 DREDGTNG VOLUME OF SLUDGE IN RIVERS AND LAKES

3

1000 m

Fiscal National Prefectural

year works works Total

1958 - 70 -- 7,004 7,004

1971 125 952 1,077

1972 119 949 1,068

1973 195 1,140 1,335

1974 146 656 802

1975 166 545 711

1976 157 654 811

1977 125 882 1,007

1978 200 860 1,060

1979 288 804 1,092

1980 353 594 947

Total 1,874 14,985 16,859

417
VS1Y 1 v.'.~- .. ,r wmrtkr 7--

TABLE 12 DREDGING VOLUME OF SLUDGE IN RIVERS AND LAKES,

CLASSIFIED BY REGION

1000 m

3

Number of

Region rivers Total plan (%) 1980 1981 1982

Hokkaido 1 700 1.5 186 90 424

Tohoku 2 215 0.5 121 6 88

Kanto 30 20,533 43.1 6,382 382 13,769

Hokuriku 5 1,486 3.1 270 22 1,188

Chubu 10 9,294 19.5 2,260 126 6,908

Kinki 17 11,385 23.9 2,834 142 8,409

Chugoku 14 2,305 4.8 350 79 1,876

Shikoku 4 265 0.6 114 30 121

Kyushu o 1,446 3.0 975 61 410

Total 92 42,629 100 13,498 938 33,193

418
TABLE 13 UNIT COST OF DREDGING OF SLUDGE IN RIVERS

AND LAKES (1980)

Unit cgst Other.

yen/m Kanto and Kinki Regions Total

1,000 under -- 1 1

1,000 - 2,000 7 6 13

2,000 - 3,000 4 8 12

3,000 - 4,000 6 11 17

4,000 - 5,000 3 6 9

5,000 - 6,000 5 3 8

6,000 - 7,000 5 -- 5

7,000 - 8,000 4 1 5

8,000 - 9,000 2 -- 2

9,000 - 10,000 2 --

10,000 over 5 -- 5

Total 43 36 79

419
TABLE 14 flTHOD USED FOR DMEDGIN( OF SLUDGE

IN RIVERS AND LAKES (1980)

Instrument Case

Clamshell grabbing crane 12

Pump dredger 23

Grab dredger 30

Tractor shovel (and bulldozer) 10

Backhoe 12

Dragline I

Others 3

Total 91

420
TABLE 15 TRANSPORT METHOD OF

SLUDGE (1980)

Instrument Case

Dumrp car 40

Barge 18

Pipeline 9

Tractor shovel 1

Barge and dump car 6

Pipeline and dump car 5

Flat ship and dump car 3

Others 7

Total 89'

421