US Army Corps

of Engineers

Water Resources

Support Center

00Cf)

S,-Management of Bottom Sediments

i Containing Toxic Substances

Proceedings of the 9th US/Jap n

Experts Meeting

17-19 October 1983

Jacksonville, Florida

Thomas R. Patin, Editor

DTIC

--. JUL 2 5 '685

'.March 1985 15 30
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MANAGEMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC Final report

SUBSTANCES: > EXPETS METING. PROCEEDINGS OF THE 9TH U. S./JAPAN PERF3RMING ORG. REPORT NUMBER

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IS. KEY WORDS (Conetm"e - r0~6 4id. it n.cee*ay omw Iteflly 1' block mink..)

-,Dredging,;

Marine deposits,

"Sedimentation

"Toxicology. '---

"* St AUSTUAC? (Cnt -m -a• It ..a • I#lp6Jy h• Stoc mminklr

The 9th U. S./Japan Meeting on Management of Bottom Sediments Containing "Toxic Substances was held 17-19 October 1983 in Jacksonville, Florida. The "meeting is held annually through an agreement with the U. S. Army Corps of

Engineers and the Japan Ministry of Transport to provide a forum for presentstion of papers and in-depth discussions on dredging and disposal of contami-

"nated sediment. q ; 6 - i

,* Unclassified

SCCumRTY CLaSSIFICAYTOW1 OF THIS PAiC (WI51m Ot.t ic

'o
PREFACE

The 9th U. S./Japan Meeting on Management of Bottom Sediments Containing

Toxic Substances was held 17-19 October 1983 in Jacksonville, Fla., USA. The

meeting is held annually through an agreement with the U. S. Army Corps of

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

"".-tion of papers and in-depth discussions on dredging and disposaJ of contaminated sediment.

COL George R. Kleb, Coimander and Director of the Water Resources Support

Center (WRSC), was the U. S. Chairman. Mr. Ikuhiko Yamashita, Ministry of

Transport, Tokyo, Japan, was the Japanese Chairman.

Coordinator of the organizational activities and editor of this report

was Mr. Thomas R. Patin, program assistant, Dredging Operations Technical Support Program (DOTS), U. S. Army Ingineer Waterways Experiment Station, Vicksburg, Miss. Mr. Charles C. Calhoun, Jr., was Program Manager, DOTS. At the

"time of publication of this report, Dr. Robert E. Engler was Program Manager

of DOTS.

SCCeSSIon For

ANTIS GRA&I

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CONTENTS

Page

I PREFACE ............................. ................................ 1

ATTENDEES ................................ 4

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

i JOINT COMMUNIQUE .................. ........................ *. . . . 7

AERATION EFFECTS ON MARINE EUTROPHICATION

- by I. Yamashita, M. Shikamori, and T. Horie . . ........... 8

HYPOLIMNETIC OXYGEN DEFICIT IN A EUTROPHIC LAKE AND THE ROLE OF SEDIMENT OXYGEN "EMAND by M. Okada, R. Sudo, M. Takasaki, and A. Sato . . 27

"THEORETICAL CONSIDERATIONS OF GRAVITY DEWATERING OF DREDCED

. MATERIAL THROUGH THE BOTTOM OF A CONTAINMENT AREA by T. Yoshfda . . . 41

RAPID DEWATERING TEST OF DREDGED MATERIAL IN SITU by M. Nakwwura . . . 63

SMECHANICAL DEWATERING OF DREDGED SLURRIES

- by P. Erickson and J. Hurst . . . . . . . . . . . . . .... . 74

DISPERSION OF SEDIMENT RESUSPENSION CAUSED BY DREDGE i OPERATION by H. Kcba . . . . . . . ...... . . . . . . . . . 90

AN ANTI-TURBIDITY OVERFLOW SYSTEM (ATOS) USED FOR REDUCING THE

"DISPERSION OF FINE SEDIMENTS FROM A DREDGE PLUME

* by M. Cruickshank . . . . . . . . . . . . . . . . . . . . . 106

NEW TECHNIQUES DEVELOPED IN JAPAN FOR OIL SPILL CLEANUP

by I. Ofuju and N. Ishimatsu . . . . . . . . ........ . ... 114

"THEORETICAL CONSIDERATION OF POND AND SPILLWATER TREATMENT

-" DESIGN by Y. Yoshida and M. Natori. . . . . . . . ... . . . . . .. 132

ST. LAWRENCE SEAWAY PRECISE NAVIGATION by D. Robb . . . . . . . . ... 145

MEASUREMENT OF NUTRIENT CONCENTRATIONS IN SEDIMENT PORE

WATER COLLECTED BY A DIALYSIS SAMPLER

by Y. Kurimoto and T. Kotake . . . . . . . . . . . . . . . . . . . . 150

ACCUMULATION OF ACRYLAMIDE INTO FISH by J. Asada, T. Shinlzu,

S. Tajia, F. Sakauoto, and M. Fujiki . . . . . ........... 161

. LONDON DUMPING CONVENTION UPDATE by R. Engler . . . . . . . . . .... 173

• -ALTERNATIVES TO OPEN WATER DISPOSAL OF CONTAMINATED DREDGED MATERIAL a by C. Coch, J. Tavolaro, R. Krauser, and P. Tischbein ........ 176

2

I
Pago

REHABILITATION OF ESTUARIES IN TSU-MATSUSAKA HARBOR

by S. Hamaguchi . . . . . . . . . . . . . . . . . . . . ........ 198

SUBSURFACE INVESTIGATION FOR DREDGING PROJECTS by R. Brissecte . . . . 210

.lEIEFICIAL USES OF DREDGED MATERIAL: AQUACULTURE IN DREDGED

MATERIAL CONTAINMENT AREAS by J. Lunz .... ............. 226

3
ATTENDEES

9th ANNUAL

U.S./JAPAN EXPERTS MEETING

Japanese Delegation

Mr. Ikuhiko Yamashita. Cochairman Director, Environment4l Protection Division, Bureau of Ports and Harbours,

Ministry of Transport

Mr. Shoi.chi Hamaguchi Deputy Head. Construction Section. Hie Prefectural Government

Mr. Mitsunass Okada Researcher. Laboratory of Freshwater Fnvironment. NatF-;.ai Institute for

Environmental Studies, Environment Agency

"Mr. Motoo Fujiki Professor. Environmental Medicine. Institute of Community Medicine.

University of Taukuba

Mr. Takao Yoshida Japan Bottom Sediments Management Association

Mr. Yooji Kurimoto Japan Bottom Sediments Management Association

Mr. Tatsuo Kotake Japan Bottom Sediments Management Association

Mr. Makoto Natori Japan Bottom Sediments Management Association

Mr. Hiromi lobs Japan Dredging and Reclamation Engineering Association

Mr. Ichiro Ofuji Japan Workvessel Association

Mr. Maoshi Ishinatau Japan Workvessel Association

Mr. Ivao Danjo Japan Bottom Sediments Management Ast ciation

Mr. Takatoshi Inoue Takenaka Konuten Construction Company

Mr. N. Nakamura Japan Bottom Sediments Management Assor.,ation

U.S. Delexation

Colonul Geirge 1. [lab. Cochairman Cimsonder/Director, Water Resources Support Center, Corps of Engineers

Mr. Williem 2. Wurden Chief. Dredging Division, W4ter •-cources Support Center.

Corps of Engineers

Mr. Robert Engler Corps of Engineers, Waterways Experlment Station

Mr. Paul A. Erickson Director. EnvironEnergy Technology Center. Corporate "s.search and

Innovation Group. Raxnord Corporation

Mr. Michael J. Cruickshank Minerals Management Service. Department of the Interior

Mr. David Robb St. Lawrence Seamay Development Corporation, Department of Tvansportation

Mes. Carol A. Coch Corps of Engiseers. New York District

Mr. Jef! McKee Corps of Engineers, Baltimore District

Mr. R. F. Brissette Canonie Emgineers, Canonie Environmental Services Corporation

Mr. John D. Lunn Corps of ngineers Waterways Experiment Statiom

Mr. Charles C. Calhoun Corps of Engineers. Waterways Experiment Station

Mr. Jams Bradley Corps of Engineers. South Atlantic Division

Mr. Girlamo Di Chiara Corps of Engineers. Jacksonville District

Mr. Neill 1. Parker Institute for Water Resources. Water Resources Support Center.

Corps of Engineers

/4
AGENDA

9th U.S./JAPAN EXPERTS MEETING ON MANAGEMENT

OF BOTTOM SEDIMENTS CONTAINING

TOXIC SUBSTANCES

Jackson',ille, Florida

17-19 October 1983

Cochairmen

Mr. Ikuhiko Yamashita

Director, Environmental Protection Division

Port:s and Harbours Bureau, Ministry of Transport

COL George R. Kleb

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

Monday, October 17, 1983

0830 Welcoming Remarks Brigadier General Gay

Response - Chairman Yamashita

Response - Chairman Kleb

0900 Aeration Effects on Marine - Mr. Yamashita

Eutrophication

0930 Hypolimnetic Oxygen Deficit in a - Mr. Okada

Eutrophic Lake and the Role of

Sediment Oxygen Demand

1000 Break

1030 Theoretical Considerations of - Mr. Yoshida

Givity Devatering of Dredged

Material Through the Bottom of a

Containment Area

1100 Rr.pid Devatering Test of Dredged - Mr. Nakamura

Material In Situ

1130 Lunch

1300 Mechanical Devatering - Mr. Erickson

5
1330 Dispersion of Sediment - Mr. Koba

Resuspension Caused by Dredge Operation

1400 An Anti-Turbidity Overflow System - Mr. Cruickshank

Used for Reducing the Dispersion of

Fine Sediments from a Dredge Plume

1430 Break

1500 New Techniques Developed in Japan - Mr. Ofuji

for Oil Spill Cleanup

1530 Theoretical Consideration of Pond - Mr. Natori

and Spillwater Treatment Design

1600 St. Lawrence Seaway Precise - Mr. Robb

Navigation

1630 Adjourn

Tuesday, October 18, 1983

0800 Measurement of Nutrient Concentrations - Mr. Kurimoto

in Sediment Pore Water Collected by a

Dialysis Sampler

08?1 Accumulation of Acrylamide into Fish - Mr. Fujiki

0900 London Dumping Convention Update - Mr. Engler

0930 Alternatives to Open Water Disposal of - Ms. Coch

Contaminated Dredged Material

1000 Break

1030 Disposal Are& Management - Mr. McKee*

1100 Rehabilitation of Estuaries In - Mr. Hamaguchi

Tsu-Matsusakq Harbor

1130 Lunch

1300 Subsurface Investigation for - Mr. Brissette

Dredging Projects

1330 Beneficial Uses of Dredged Material - Mr. Lunz

1400 Break

1430 Closing Remarks - Chairman Kleb

- Chairman Yamasbita

1530 Adjourn

* No text available.

6
JOINT COMMUNIQUE

The ninth meating of experts pursuant to the Agreement Between the

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

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

Mr. Ikuhiko Yamashita, Director, Environmental Protection Division, Ports and

Harbours Bureau, Mini3try of Transport, Japan, and Colonel George R. Kleb,

Commander and Director, Water Resources Support Center, U. S. Army Corps of

Engineers. The purpose of the meetings conducted under this agreement is the

exchange of information in regulatory, technical, and operational areas relevant to manaSement of bottom sediments and the exploration of areas where

joint effort appears fruitful.

Experts from both countries presented technical papers on a variety of

subjects including arresting and raversing eutrophication in both saltwater

and freshwater water bodies, dewatering of dredged sediments, rontrol and minimnization of turbidity during dredging, management of dredged sediment disposal and containment activities, alternatives to ocean disposal of dredged

sediments, effects of contaminated sediments on the chemical and biological

environmetts, rehabilitation of contaminated water bodies, and constructive

uses fur dredged sediments.

This ninth meeting was highly successful and fruitful. The information

exchange was very effective. The confevees generally agreed that the dredging

technology and sediment management programs of both countries will significantly benefit. The Co-Chairmen agreed that the next meeting will be in Japan

in 1984 and that the date will he decided jointly.

Dir.etor, Environmental Commander/Director, Water Resources

Protection Division, Ports and Support Center, Corps of Engineers

Haebours Bureau, Ministry of

Transport

IKUHIKO YAMASHITA OLONEL BORCE R. KLEB

Oct. 18, 1983 Oct. 18, 1983

7
AERATION EFFECTS ON MARINE EUTROPHICATION

Ikuhiko Yamashita

Director, Environmental Protection Division

Bureau of Ports and Harbours, Ministry of Transport

Kasumigaseki 2-1-3, Chiyoda-ku, Tokyo

Masazumi Shikamori

DirecLur, Environmental Protection Division

The Fifth District Port Construction Bureau, Ministry of Transport

Tsukiji-cho 2, Minato-ku, Nagoya-shi, Aichi-ken

Takashi Horie

Chief, Laboratory of Sea Water Purification

Port and Harbour Research Institute, Ministry of Transport

ABSTRACT

This report briefly presents the results of a

study on the application of an aeration system to a

marine environment. A multi-hole, tube type aeration

device was tested in a nearly closed sea area. The

effectiveness of the system, primarily in destratification, was confirmed. This study, which includes

preliminary studies on actual examples, laboratory and

field experiments, development of simulation systems,

etc., is being conducted primarily by the Fifth District Port Construction Bureau of the Ministry of

Transport.

BACKGROUND AND OBJECTIVE

Aeration Effect

Organic matter in the water is absorbed, oxidized, and decomposed by

aerobic bacteria. Through these processes stable inorganic matter, such as

H2 0, C02 , and nutrient salts, is released into the water when enough dissolved

oxygen (DO) is present. In an anaerobic condition, on the other hand, the

organics are reduced by anaerobic bacteria evolving methane gas, hydrogen

sulfide gas, etc., wnich may cause an offensive odor. Some nutrient salts

would also be released from bottom sediment.

The laboratory experiment showed that the release rate of phosphate-P

from the bottom sediment decreases markedly when DO exceeds 2 ppm, a6 shown in

Figure 1.

This fact suggests that depletion of DO in the water can 5a one of the

main causes of deterioration in the quality of water and bottom seeiment.

8
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Figure 1. Relationship between release

rate of nutrieut salts and DO

Also, the aeration which supplies oxygen directly into the water is thought to

reduce phosphorus release into eutrophic water. Aeration effects are diagramed in Figure 2. It should be noted from this figure that biochemical and

physical factors must be considered. Experiments on aeration systems for

lakes and reservoirs have been conducted in several countries and the effectiveness of aeration systems is being clarified. Some systems are being

installed for practical use. However, no known aeration systems have yet been

applied in seawater. The application of an aeration system in seawater is

considered impractical due to the openness of the area. However, it does

appear possible to apply an aeration system effectively in a closed or

semiclosed bay or port area. Since 1980 the Fifth District Port Censtruction

Bureau has conducted experiments in situ and in the laboratory to investigate

the physical and economic viability of an aeration system.

Scope of the Study

This study is being carried out according to the flowchart shown in Figure 3. In the first year (1980), a literature survey was conducted to determine the state of the art in this field and to examine the applicability of

aeration systems to ports and bays.

In 1981, a series of laboratory experiments were conducted in cooperation

with the Port and Harbour Research Institute to determine DO concentration and

flow pattern and destratification caused by aeration.

In 1982, a series of in situ experiments was conducted at the Port of

Shimizu in Shizuoka Prefecture to confirm the effects of the multi-hole, tube

type aeration system.

Future studies will include the development of a computer simulation program and a series of large-scale field experiments.

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Examination of Implementationl *t Laboratory Field oeffcton nviron- o of large-scale

sura xpeimnt xprimnt ment improvement Ifield "and estimation of experiment.

"evelopment of Development of

aimualati~ft si..alat~on system on system on the improvement of water

current gener- qualicy. • /.atd by '

" Figure 3. Flowchart of the study

%" Comparison of Various Aeration

Systems (Outline of the 1980 Study)

Most of the aeration systems proposed to date can be classified into

"three major types: air (oxygen) blowing, mechanical, and hydraulic. These

"types can be classified further into several minor types as shown in Table 1.

"The "Number of Examples" column for each type includes those proposed in

"overseas countries as well as domestic.

The total number of examples is 81, and about half are domestic. Of

these. 15 (19% of the total) are at the stage of practical use. Among the

total number, the multi-hole, tube type system is dominant.

Fox DO, oxygen dissolving efficiency,* and power efficierncy,t the

multi-hole tube system with fine air bubbles has a comparative advantage.

This advantage is increased when the vertical mixing of water due to the

upward flow of air is considered.

An overall comparison of costs and methods of installation, maintenance

and repair, possible secondary pollution, harmony with the surrounding

scenery, and influence on marine traffic shows that the multi-hole tube and

the wave breaking and/or absorbing systems show high performance.

The hydraulic turbine system is also effective in cases where power-

,* generating turbines are installed at canal zones. Artificial cascades and

dams are also considered effective when installed at canal zones. Therefore,

these two types have potential application to port and harbour areas.

The system utilizing wave absorbing and breaking actions may satisfy all

"requirements, but this type is not constructed primarily for aeration; its

aeration effect is supplementary. Also, port waters are relatively calm,

resulting in less aeration. The surface stirring system seems to be very

effective in improving the quality of water from coastal waste disposal sites.

• "Oxygen Dissolving Efficiency DO D Increase

Efcec Oxygen Supplied for Aeration

•" DO Increase •"$Power Efficiency DOIces

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From this discussion, it can be seen that every aeration system seems to

have potential application to ports and harbours, depending on the installation conditious.

Effect of Aeration in the Laboratory

Experiments (Outline of the 1981 Study)

The results of the 1980 study exhibited the applicability of the multihole tube system to ports and bays when compared with other systems. Therefore, the laboratory experiment in 1981 concentrated on the multi-hole, tube

type aeration. Aeration effect, which depends on shape of air blowing tubes,

sizes of air blowing holes, and amount of air blown, was measured and examined

using the amount of dissolved oxygen and destratification as indicators.

Experimental Method

A water basin 10 m x 10 m x 1 m was used along with the three types of

air blowing tubes shown in Figure 4. Twelve variations were tested with different hole sizes, hole numbers, and varjing amount of air. The procedure of

the experiments was as follows:

a. In order to reduce the DO, sodium sulfate and cobalt chloride were

added to the basin and the water stirred for about 30 min.

b. Aftar the water became still, the initial DO concentration was

measured.

c. After aeration began, DO and water flow velocity were measured every

30 min to 1 hr urtil the DO level reached 7 to 9 ppm.

Results

Results of the experiments are shown in terms of the change of DO in

Figures 5-7 and are discussed below:

a. Shape of air blowing tube. As shown in Figure 5, oxygen dissolves

the most in B type tubes, and the least for C type tubes. But, the

*, differences among types are not significant. The difference in the

oxygen dissolving efficiency among types cannot clearly be seen in

"the laboratory experiment in which a basin surrounded by walls is

used. These walls make outward oxygen dispersion impossible.

"" b. Size of air blowins holes. As shown in Figure 6. even if the same

amount of air, 80 I/min, is blown through the same type tube (C), the

amount of dissolved oxygen differs depending on the size of the air

holes. It is clear that the smaller the diameter of the hole, the B more oxygen that dissolves into the water.

c. Amount of air blown. As shown in Figure 7, three different air

levels (80, I10, and 240 I/min) are used and it can be clearly seen

that the higLer the level, the more the oxygen dissolves.

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•: A RVO.C•, 50.6am, 9~/i8 (e.vve. %*I figs.A ai, ust ON air blow",)

I CVp.000. 5.40 &/Oda

S C t tw 0

0a €l * - - a

6

I il a. 00

0 2 4 • I 0I 121 14• Iik 18 20 U• 24, T1I. 1i

Figure 5. Change of nondimensional oxygen dissolving

rate with time, shape of tube

"3.4g "AM-4UNmAmgLO inaYge dlaaeLvlsringtu Ws aptnuaa as

C* "BRSoreId £eatems •tles ON 00 (Auvrap Value tI h tlstis$ veisal).

Ca W etta.• e aftIIe of 0O (AhtNO valve Is the Caes0LI

v .essl).

C. S1 4S. towd commaeitnIg of gO.

C: 6 "ya. O.II 110&/a"l

S at C type I.*=• 6 i/aOdI O as em€ y I.Ona 164 1/,=•da

C Z" type 66 0. 6 @/a"A &. N

It'

I iI I

0 -

S2 '4 6 1 to 12 14 ,4 is 20 a2 2.

Ti.b hr

Figure 6. Change of nondimensional oxygen dissolving rate with time, size of hole

Effect of Aeration in the Field

Experiment (Outline of the 1982 Study)

The field experiment to determine improvements in water quality caused by

aeration was conducted in 1982 at a closed sea area. At this area the

exchange of seawater is comparatively small and the seawater has been polluted

to a certain degree. Selection of types of air tubes and levei of blown air

was based on the results of the 1981 laboratory experiment. Fled of seawater,

destratification, and change in water quality were measured. The outline of

the experiment is discussed in the following paragraphs.

17
to

A: Ct y~0. Sm 00I/Itin

a : C type 0. 5m 160/fda

0: C type . =m 20L /in

1 10 12 16 1y ae 20ls~ 22 2

-~ a

0 0 - 0

0t Tim 

0 ao

o .

* 1i 0 I 1 . £II • 2 2 &

Figure 7. Change of nondimensional oxygen dissolving

rate with time, amount of air

Site

As can be seen in Figure 8, a 30- x 70-m area in the No. 1 timber basin

at the inner part of Shimizu Port, Shizuoka prefecture, was chosen as the

experiment site. The depth of the seawater was 0.5 to 5 m with an average of

3 m. The 39-day experiment was conducted from 2 Aug to 9 Sep 1982.

Methods

The experimental equipment consisted of the air blowing tubes and a

compressor.

Two pieces of steel air blowing tubes (4.4 m long, 40 mm in diameter,

with 49 holes I in diameter at intervals of 8.8 m) were connected rZ, & air

nompression cylinder with a length of 10 m and an inner diameter of 150 mm.

Four of these compressed air cylinders were used.

Each tube was installed on the flat seabed as shown in Figure 9. Four

tubes were arranged as shown respectively in Figures 10 and 11. One or two

compressors with a capacity of 5, 10, and 20 m3/min were used, depending on

cases of the experiment.

Experimental Design

The experiment was carried out for eight cases, each changing the

alignment of the aeration tubes, the rate of air blown, and the blowing

duration (Table 2).

Observations

The current was observed to determine its generation by aeration. Water

temperature and the waount of chlorine were observed to determine the state of

stratification. The amount of DO was determined because an increase in DO

shows a direct efftct of aeration. Turbidity was observed because it

indicates possibl., secondary pollution caused by bottom sediment stirred up by

18
/0

Fuj Wu

vdhal- Port of Shimizu

No. I Tmber lTi r

basis handling

The experimet

siizu

Toky

oeThwe IfOh isurLcP 5 Port of Shimizu

Figure 8. The field experiment site

19
al I i

:1 a !: T Buoy

, 

* * .:: i: : , : : , Wire

di\` "/ ~ ~ a aIL I I I 9 * 

Air tube

Figure 9. Schematic diagram of air tube installation

Circled numer: shov ;tatIol"e. _ _____

a O cher a biers how depth of the weter (in). 4 los

b

60 1 4 . 4 4 4.0

2-S

4. 4.1.0O4.

", 0.5 . k8. 61 

t 2

I.

0.

c d

Figure 10. Alignment of the air tubes and stations,

Type I

20
Circl&e numbers show stations. 2i 4 lOw

a Other numers show dptn of theter (a). b

50.0 4.5 )**4 a

44 2.0

3I 9

A- -A

c d

Figure 11. Alignment of the air tubes and stations,

Type II

TABLE 2. EXPERIMENTAL CASES

Rate of Air Blown Blowing Duration

Case Type* (NM3 /min) hr Date of Experiment

1 I 10 24 2-3 Sept 1982

2 I 20 24 6-7 Sept 1982

3 II 10 24 10-11 Aug 1982

4 II 20 24 13-14 Aug 1982

5 II 40 12 16 Aug 1982

6 II 10 144 20-26 Aug 1982

7 II 5 24 18-19 Aug 1982

8 II 10 24 28-29 Aug 1982

* As shown in Figures 10 and 11.

21
aeration. Chemical oxygen demand and nutrient salts (T-N, T-P, NH4 -N, PO4 -P)

were observed to determine decomposition of organic matter and decrease of

nutrient salts affected by an increase in DO.

Methods of Measurement

At stations 1 - 18 shown in Figures 10 and 11, horizontal and vertical

current directions and current ve"ncities of seawater were measured at deptl.

intervals of 1.0 m from the sea surface to the sea bottom. The measurement

was made about every 6 hr corresponding to the low and high tide during the

aeration experiment.

To determine change in water quality caused by aeration, waier temperature, amount of chlorine, amount of dissolved oxygen, and turbidity were measured with a multipurpose water quality measuring meter and a turbidimeter at

the same points and the same times as the current measurements. The measurements were continued for 24 hr with 6-hr intervals after aeration ceased.

Changes in organic matter and nutrient salts in rhe seawater by aeration were

measured through samples taken at three points for two layers; COD, T-N, T-P,

NH4-N, and PO4-P were also measured.

Results

Vertical seawater currents generated by aeration were observed only

very close to the air tubes. Horizontal currents, however, prevailed in the

surrcunding area. The horizontal currents were fairly strong (about

10 cm/sec) more than 30 m away from the air tubes. The results from case

No. 3 of the experiment, which is considered a fundamental case, are shown in

Figure 12 (current velocity before the experiment was zero).

Changes in the generated water current caused by the differing alignment

of the air tubes and the amount of air blown showed that the more the air was

blown, the stronger the water current. This effect extended along the dirýction vertical to the air tubes for the type II arrangement. On the other

hand, for the type I, the generated water current was weak and small in scale

and the change in the current caused by the rate of blowing air was unclear.

It was clear from the data on the vertical distribution of water temper-

,tture, amount of chlorine, etc., that stratification of seawater disappeared

6 hr after aeration began and the seawater within the experimental area was

almost homogeneous after 24 hr (Figures 13-16). Six hours after aeration

stopped, however, stratification reappeared except for case No. 6. Therefore,

the effect of aeration seems to disappear in a fairly short time after aeration ceases. For case No. 6, in which aeration was continutd for a long time,

the seawater within the experiment area remained comparatively homogenous even

2 days after aeration ceased.

Dissolved oxygen increased rapidly after aeration began and decreased

rapidly after aeration ceastJ. The increase in DO was almost proportional to

the amount of air blown. A large fluctuation in the DO level was found during

the aeration (Figure 17).

22
0.01 0.08 0.22 0.07 0. 11

---- >~- :* .0.12 0. 1

0.04

0.15 - -~..45; 0.04-

a. 0. .r s 0., 60

0.01

()') (4) (4) (I) (9) m1 (4 (1STATION NO.

(seA 3

Figure 12. Sectional distribution of flow rate vector -A-A section

24 hr after the beginning of aeration (units are in

metres per second)

5.1 25.5 25.4 26.0a 26. 2 26.0 5.5 21&4-.267 26 0 256A25. 26 0 26.5 27.4

345..-~ 25.0

26. ------

U.1 6.3 2L U9 s. No.3 STTONN

ft 1

28.2n. 18.1 2.9 I3
2C. 8 3. 3 2L.0 21.3 23.1 21.1 21.5 21.9 21.0 26.6 24.6 24.5~

H 34.00

In s

26.5 51. -- - - -- - 21. 21.3 29. . I U1. 514 2. 9 .5

U2n. I .2n2 S ~ - .

I0

1. 22.36_

21.5 ~ ~~~ 23.1.-2. 43 too1. 

Ca"e No. 3 STATION NO

Figure 14. Sectional distribution of water temperature -A-A section 6 hr

afteir aeration began (units are in degrees Centigrade)

24.5

25125.0 26.9 24.4 24.2 24.2 24.2 24.2 2U.3 24.

25.0

245-U524.7 24iS 24.2 24.3 24.2 24.3 H24 24.3

24.5 2.i 5 24.3 V4.2 24.3 24.2 24.3 244

24.3 34. M.2U-224.2 21. 24. 1,

(~I ,i I VSTATION NC

Case No.3

Figure 15. Sectional distribution of water temperature -A-A section 24 hr

after aeration began (unitq are in degrees centigrade)

24
"" i

S'6. S S.•

:5- 250 216 2. 6 A C12. 2s-o

• "" v •.025.0,

" •~~.0 , .,.

" Ioo

----------- -

...... .... 1

* - ae I. a

* "s I t

n28.1 U. 1 21.2 2L -1.S

L 0.1 t 

1 2D" 0 

I S 0

il a

.Fgure 16. Sectional. distribution of rater temperature -A-A section 6 hr

,-af ter aeration ceased (units are in degrees Centitgrade)

nWIN _---Wacelr doott - I a

• 0 L.-i 1 r e..\-..-.

6'1 Jus before the -I LH.L IL LH L,' 1 1 L LH:LH l cidem

F r . o r n d o oye bera

" ~5- /•,\H: Hi.gh Tzde

• •, • L: Low Tide

44

I +" • "" /" • ,W- 41,A1 :" , % ",,, • ; .4. .

:+2- •

S• :,,mmm.Aelration

-,L H L H L H L, H L, H! L H L, L L L_ L L L, M L, HL H L H L Tideo

SFigure 17. Comparison of dissolved oxygen betveen the upper

•. and lover layers

.+• !!25
Decreases of organic matter due to their decomposition and decreases of

nutrient salts due to their oxidation were also recognized (Figure 18).

p

(Pp.)Qi,'n aC 4 Ca-S Cu•? C,,8- Ch ( Ia1 Ce2

0. ' I- P

S II 4 I

54) 0 12~

14

1. 0.6

0, 0,4 0404 ** i , ,4 "4, 0*-..-. . . . .__ ___ 4 .

0.02p

101 1281 1i5 7I821 it 2a I 13 2 I5 .

0i

Fiur 1. hag ofl toa hopo (P) adpopaepopou P P

"'"~~ 0.121'. ~~~ , , i

0 0o. .. ... .......

S,--I~ 0,06 ~ ''

It has bee shw tht eato ca ea, fecie to in povn the arin envirnment Hoevr r dealdsuisad eieeto*h

1'. 0 11 12 13 W4 15 16 17 13 19 X 21 22 23 XI 5 I V' 3 22 30 31 1 2 II 4 5 GI T 1 Day

iFigure 18. Change of total phosphoruts (T-P) and phosphate phosphorus (PO 4-P)

I'-"during the experiment (station 2)

r • CONCLUSIONS

'"m It has been shown that aeration can be an effective method in improving the marine environment. However, more detailed studies and refinement of the

method are needed. Studies are needed on the effects of a system in which

several types of air tubes are combined and operated in a wider sea area, the

effects of a longer operating time, the effects of intermittent operation, and

the effects of differing air rates.

Furthermore, the cost performance of the aeration method needs to be

compared with that of alternative measures. Possible alternative measures

"will include methods to reduce the release of COD, etc., from the sea bottom

such as sediment dredging and covering the sea bottom with a clean sand layer, and methods to promote replacement of eutrophic seawater with oxygenated seawater by pumps or other means.

26
HYPOLIMNETIC OXYGEN DEFICIT IN A EUTROPHIC LAKE

AND THE ROLE OF SEDIMENT OXYGEN DEMAND

Mitsumasa Okada, Ryuichi Sudo

Laboratory of Freshwater Environment

The National Institute for Environmental Studies

P.O. Tsukuba-Gakuen, Tsukuba, Ibaraki 305 Japan

Mitsuru Takasaki, Atsuhisa Sato

Department of Civil Engineering, Tohoku University

Aoba, Aramaki, Sendai 980 Japan

ABSTRACT

Lake surveys and in situ experiments were conducted to study the hypolimnetic oxygen deficit in a

eutrophic lake, Lake Yunoko. A mathematical model was

developed to estimate the dissolved oxygen budget in

the lake. Production of oxygen by photosynthesis of

phytoplankton, consumption by respiration of microorganisms, sediment oxygen demand, and oxygen transfer

*, by eddy diffusion and reaeration at the surface of

water were taken into consideration. It was shown

from the budget that sediment oxygen demand plays an

important role in the first stage of the hypolimnetic

oxygen deficit in summer; i.e., the oxygen produced by

photosynthesis was not transferred into the hypolimnion

and the contribution of sediment oxygen demand was as

"large as that of the consumption in water. Restoration

techniques for the oxygen deficit such as management

of bottom sediment and control of phytoplankton produc-

,ion were discussed. The management of bottom sediment

was shown to be an effective way to control the

hypolimnetic oxygen deficit in Lake Yunoko.

INTRODUCTION

It is well known that the hypolimnetic oxygen deficit during summer

* stratification is frequently observed in dimictic and eutrophic lakes and

. reservoirs (1). The deficit causes release of phosphorus, manganese, and/or

iron from the sediments (2). Released phosphorus may enhance primary production in the overlying water. High concentrations of manganese and/or iron may

disable the direct use of the water for water works and the construction and

operation of water treatment processes for the removal of these ions increase

the cost of water works. The deficit also damages aquatic habitats.

*• Major factors to control dissolved oxygen (DO) concentration in water

bodies are oxygen production by photosynthesis and oxygen consumption by

respiration and/or sediment oxygen demand (SOD). Physical processes such as

27
-- - - -.- I .. * *-. ... I . l . ..- - , - .- _ -- - - --- - -

"reaeration at the water surface and vertical transport of oxygen by diffusion

and/or convection are also important factors to determine vertical profiles in

dissolved oxygen concentration in water, hence the hypolim-etic oxygen deficit.

Although there have been many studies on each process mentioned above,

few comprehensive studies have been presented (3-9). Lake restoration projects would be necessary to cope with the deficit in DO in the hypolimnion (10). There would be direct measures, however, to control DO levels.

Probably, those measures will bo -cri efiicient, i.e. economical and prompt,

than general measures f.z eutrophication control.

The purpose of this study is to assess the contribution of sediment oxygen demand to vertical DO profiles in a eutrophic lake. Each major process

was measured in situ. A mathematical model is presented to calculate DO budget and to assess the contribution of SOD to the budget and to the vertical

profiles of DO in the lake. Also, techniques aiming at control of the

hypolimnetic oxygen deficit were assessed through numerical simulations by the

model. The lake in this study is Lake Yunoko (surface area - 0.33 km2, maximum depth - 12.5 m). The period studied was the first stage (3 June to

9 June) of the hypolimnetic oxygen Leficit.

MATHEMATICAL MODEL

Construction and Assumptions

A water column 11.6 m deep was divided into 12 layers at 1-m intervals

except for the deepest layer (0.6 m). Dissolved oxygen concentration,

"" Ci(15m-3,i - 1-12), was defined at each layer as a state variable. The

control variables are suspended solid concentration, S (gImi), light

-2 -1 S"intensity outdoors, I (pEin-m 2hr ) and water temperature, e (*C).

0

Assumptions used to construct and solve the model equations were as

follows:

a. Horizontal distribution in DO values is negligibly small compared

with the vertical distribution.

_b. Reaecation and vertical eddy diffusion coefficients are con3tant

throughout the period studied.

o A system of equations for the model is shown in Table 1. All terms are

defined in the nomenclature on page 38.

* Values of Parameters

Values of parameters and empirical coefficients related to photosynthesis

and respiration in water and SOD were estimated by in situ experiments at Lake

"Yunoko conducted during the study period.

28

l
/

TABLE 1. SYSTEM EQUATIONS FOR THE MATHEMATICAL MODEL

dC1 D* (C2 - C1) DI

dt R1 1 + 1 HH,- 1 (H 1 + H2) 1 (1a)

dC i (C -C) D (C +÷-C) DDI

dt -R eP + H ..+ -H ,++i for 1-2-11 (0b)

dC1 2 (C11 - C1 2 ) D1 1 k --- R + P + -+ -- (c) dt12 12 H+H 1 H 12 12H2

(1121 H2 I2C12 H1 2

Vertical eddy diffusion coefficients between layers were estimated based

on the heat balance equations (11):

W0 dz - -WpD (2)

Consecutive measurements of water temperature at the indicated depth intervals

were conducted and D values at the interfaces of two layers were estimated by z solving Equation 2. No direct measurements for the reaeration coefficient

(oxygen transfer at the interface between air and water) were tried in this

study. Values reported from the Water Research Centre (U.K.) ranged from 0.26

"to 0.67 m-day (12). The reported average value, 0.55 m-day-(- 0.023 m-hr-;

see Table 2), was adopted for the following simulation.

TABLE 2. VERTICAL EDDY DIFFUSION COEFFICIENTS AND

REAERATION COEFFICIENT

D D1 D D D D D D D D D D

1 2 3 4 5 6 7 8 9 10 11

x10 2m2 .br-1

"Estimated 2.3* 3.3 4.0 3.3 2.6 0.9 1.6 1.0 0.6 1.4 0.9 0.8

" Calibrated 6.7 6.7 6.3

* A value reported from the Water Research Center, U. K., for still waters.

29
S . Procedure

. Obviously, the system equations cannot be solved analytically. A numerical procedure by the Runge-Kutta-Gill method was employed to solve the equa-

. tions (HITAC M-150, Computer Center, The National Institute for Environmental

Studies). The initial condition for the computation was taken from the

observed DO values along the depth intervals on 3 June. Among contrrl variables, suspended solids (SS) and water temperature were monitored along depth

* intervals once per day throughout the simulation. Light intensity outdoors

was monitored continuously by a illuminometer. Light intensity underwater was

, calculated following Lambert-Beer's law. The extinction coefficients were

determined from vertical distribution of SS values. Except for light intensity outdoors, the control variables were monitoved only once per day. Then,

the requisite values of the control variables during the calculation were

estimated by interpolation with Lagrange's algorithm.

SEXPERIMENTAL BACKGROUND

* Hypolimnetic Oxygen Deficit in Lake Yunoko

Limnological surveys in Lake Yunoko (located in Nikko National Park,

ca. 100 km north of Tokyo) were conducted weekly from April to August in 1981.

Intensive daily surveys from 2 June to 9 June were also conducted. This - period was the first stage of the thermal stratification in summer. Vertical

profiles of DO concentration, SS concentration, underwater light intensity, I

-(Ein-m-2 hr- 1 ), and water temperature were monitored at the lake center

(depth - 11.6 m).

I Respiration and Photosynthesis

The rates of oxygen consumption in water by the respiration of phytoplankton, bacteria, and other microorganisms and the oxygen production by the

"* photosynthesis of phytoplankton were measured in situ by the light-dark bottle

method. Several dark bottles were submerged at 0, 1, 2, 4, 8, 10, and 11 m

and sampled every 24 hr for DO determination. Light bottles were also submerged at 0, 1, and 2 m and sampled every 2 or 4 hr for DO determination.

Both rates were converted into the specific rates per I g of SS by the

* simultaneously determined SS values.

Sediment Oxygen. Demand

Submerged chambers shown in Figure I were set on the lake bottom near the

lake center (13). Bottom sediments of an area 0.4 m by 0.4 m (0.16 m2) with

*" overlying water 0.15 m deep (0.024 ms) were enclosed by the acrylic chamber.

A small amount (ca. 120 ml) of water was withdrawn from the chamber once or

7 twice per day through a sampling tube (2 mm I.D. x 15 m) by a syringe to

determine DO values in the enclosed water. The syringe was also used to

homogenize the water in the chamber by repeated injections and withdrawals of

the water prior to the sampling. The rate of SOD was calculated from the rate

"* of decrease in DO in the water enclosed by the chamber.

,* 30

, r
TUBE FOR SAMPUNG NYLON ROPE

VALVE LEAD

T SUPPORT

80

-• 400 = • -CUTTING EDGE

S1000

Figure 1. Schematic diagram of a submerged chamber

RESULTS AND DISCUSSION

Vertical DO Profiles

Vertical distribution of DO and water temperature from 3 June to 9 June

1981 are shown in Figure 2. Both the values of DO and water temperature along

the depth were uniform on 26 May indicating the spring circulation period (not

shown in Figure 2). It is clear that the period shown in the figure was the

first stage of the thermal stratification in sumer. Actually, the difference

in the water temperature between the surface and deep (deeper than 4 m) layers

increased with time after 3 June. Along with the stratification in water

temperature, the stratification in DO and the oxygen deficit in the bottom

layers are noted. Especially in the deepest layer, DO decreased from 9 g.m -3

down to less than 4 g.m in a week.

Rate of Oxygen Consumption in Water

The specific (per g SS) rate of oxygen consumption in water,

R (g 02*g-1 SS.hr-1) was assumed to be a function of both water temperature

and DO concentration (14). Figure 3 shows the dependence of the consumption

rates on water temperature. It must be noted that all the incubations shown

in the figure to determine the rates were not limited by DO concentration.

Assuming that the dependence on DO could be expressed by Monod's equation (12,

15,16), the following relatinnship was obtained:

C(3

R - (0.0072.0 - 0.0068)oS 0.25 + C (3)

31
* : WATER TEMPERATURE "C

8 C 10 12 14 10 12 14 10 12 14 10 12 14 FT,-r ,-rT- , :T I ,,F•T , , ,-.

2 - A A- 0 A- A

4-A A A A

q. 6 A 0 A 0 A * A

LU

A8 0 A A A 0A

Jw3Jut%*5 June7 Jn

10- * AiSJu

* A 0 A AIA

12 [A I 6 IA 1 t I 1

0 4 8 120 4 8 120 4 8 120 4 8 12

A :DISSOLVED OXYGEN (mg/I)

Figure 2. Dissolved oxygen concentration and water temperature along the

depth intervals (3 June June 1981, Lake Yunoko)

oft X I 1

0 8 23

&L 0

00,

o2

00

IrX 1

"0

U 010 11 12 13 14 15

WATER TEMPERATURE (-C)

Figure 3. Specific rate of oxygen consumption as a

function of water temperature

32
Rate of Oxygen Production in Water

The specific rate of oxygen production in water by the photosynthesis of

phytoplankton, P (g 02 ,g- SS.hr -), was represented by Blackman's equation

as a function of light intensity, I (UEinm-2. hr-I ) (see Figure 4)(17):

P - 2.236 x 10-8.1 for I < 30 x 105 UEin-w-2°hr-1 (4)

or

- 0.072 for I a 30 x 105 PEinom' 2 hr-l

The effect of water temperature on P was disregarded in this study because

enough reliable data to estimate the effect of temperature on the rates could

not be obtained.

%X10 -2

08 0 x

C 4

U 0'0 2 =- Ir A

IL K A

z I

00 0 10 20 30 40 X10'

0 LIGHT INTENSITY (pEin/m /)

Figure 4. Specific rate of oxygen production as a function

of light intensity

Sediment Oxygen Demand

The rate of decrease in DO in the water enclosed by the submerged

chamber, V (inW), should be proportional to the rate of oxygen consumption by

the erclosed bottom sediment, A (cW). Also, the rate was assumed to be

proportional with dissolved oxygen concentration in the water, C (g 0 2 .- 3 ).

The rate, dCV/dt, was then expressed by:

33
dCVc -A kC (5)

dt c

Giving the initial value (at t = 0) of C as 0 C , an analytical solution to

Equation 5 could be obtained as follows:

A

ln C - - -c kt + ln C (6)

c

Then ln C could be plotted against as shown in Figure 5. The solid line in

Figure 5 was secured by the method of least squares and gave the value of the

rate constant for SOD, k, as follows:

3

3x A chamber 1

2 eA chamber 2

C

-1

0 100 200

t (hr)

Figure 5. Decrease in DO in the chamber (ln C)

with time by SOD

A

A c k -2

_v- k - -1.64 x 10-, then

k - 0.024 x 1.64 x 10-2 2.5 x 10-3m hr-1

0.16

Vertical Eddy Diffusion Coefficients

Vertical eddy diffusion coefficients, D (m 'hr -1:i - 1-12), were estimated

from Equation 2 for each interface of the two layers. The values estimated

are summarized in Table 2. Diurnal variation in water temperature at the

34
surface layers made the determination of Di values from Equation 2 difficult.

It must be noted, therefore, that the Di values near the surface may be less

reliable than those for deeper layers.

Calibration

Although calculated DO values (Equation 1) at depths greater than 3 m

were in agreement with the observed values, those values near the water

surface deviated from the observed values if the eddy diffusion coefficients

in Table 2 were used (not shown here). The model was then calibrated for the

eddy diffusion coefficients of surface layers, i.e. DI, D2 , and D3. As

mentioned above, these values were relatively unreliable estimates. The

calibrated values of Di (i - 1-3) ranged from 1.5 to 2 times as large as the

originals as shown in Table 2. The calculated DO values after calibration

were in good agreement with the observation as shown in Figure 6 (see the

control for calculated values and observed data in the figure).

•\;# 1" 11",

E 0

0

Fu6 6 12

Em

0 observalesdDOprofile - oar control

---- 0.5 x SS

S...... 2.0 x SS

3 4 5 6 7 9 4 3 6 7 a 9

JUNE 1901

Figure 6. Effects of change in SS

values on DO profiles

35

' • . i , i i i i i I I 'II ! I .
Oxygen Budget

An oxygen budget calculated from the calibrated model is shown in

Figure 7. The largest change in DO value (ADO) was noted at the bottom layer

(i - 12). Values in the figure show the contribution of each factor, i.e. the

average (between 3 and 9 June ) rate of change per day in DO values of the

layer expected by the contribution of the factor.

OXYGEN SUPPLY TRANSPORT BY CONSUMPTION BY RATE OF CHANGE

3Y PHOTOSYNTHESIS EDDY DIFFUS!ON RESPIRATION IN DO PER DAY

I___023. WATER SURFACg..

-2.07 ------ 0.98 0.11

0.80 2 ' 0.87 0.03 2--0.85.

0.28 3 0.36 0.70 -0.13

0.09 0.15. 0.51 -0.21

0.03 0.0 0.39 -0.23

0.01 6 0.0- 0.31 -0.27

7 0.0__ o 0.27 -0.27

8 0.021- 0.24 -0.25

I 0.0 . 0.20 -0.24

10 0.13. 0.16 -0.23

11 0.33. 0.12 -0.32

S:~... . . .:.:....: ":.'..•.....-..•..:..-..

:~~~~~.:.'.:-'..'..!:.,.,.,..................................-:.

Figure 7. Dissolved oxygen budget in Lake Yunoko (3-9 June 1981)

Oxygen supply by photosynthesis was largest at the surface layer (i 1)

and decreased with depth. The photosynthetic supply was negligible in layers

greater than 5 a (i • 6). The rate of oxygen consumption also decreased with

depth. The rate of consumption in the bottom layer was only one tenth of that

in the surface layer. Instead, the SOD played a remarkable role on the

largest deficit in DO at the bottom layer (i - 12).

36
Vertical eddy diffusion transferred oxygen from surface layers to deeper

layers. The oxygen produced in the surface (photic) layers was transferred

downward until the sixth layer. However, the amount transferred decreased

with depth and no vertical transfer was noted between layers six and seven.

Therefore, the oxygen supply by photosynthesis into the water column was

effective in maintaining DO levels only in the upper layers (i - 1-6).

Contrary to the upder layers, the amount of transfer increased with depth in

the hypolimnion (i - 8-12). The transfer compensated for the large

requirement of oxygen by the sediment and decreased DO levels in the

hypolimnion.

Restoration Techniques for

the Hypolimnetic Oxygen Deficit

Regardless of the actual techniques undertaken (10), the effects of the

decrease or increase in SS values on the deficit dere assessed. Note that SS

in this study corresponds to the phytoplankton production in the lake. Out of

several simulation runs where the SS values were changed from 0.01 to 5 times

as large as the observed values along the depth intervals, the results of runs

with 0.5 or 2 times present SS values are shown in Figure 6. The control in

the figure corresponds to the case for observed SS values. Although a

relatively rapid decrease in DO was noted at the sixth layer (5-6 M), if SS

values were assumed to double, little differences in DO were noted in the

bottom layers (i - 11, 12). Similarly, the decrease in SS values (xO.5)

showed little differences in DO profiles of the bottom layers. Polak (7) and

Schnoor (9) reported independently that oxygen consumption in water was the

major factor for the hypolimnetic oxygen deficit and the role of SOD was

small. Contrary to the lakes studied by these authors, SS values had little

effect on the first stage of the hypolimnetic oxygen deficit in summer in Lake

Yunoko.

The effects of SOD on the hypolimnetic oxygen deficit were studied by

simulation runs where the rate constant, k (Equation 5), was changed from 0 to

5 times as large as the estimated value. Figure 8 shows calculated DO values

where the k value was 0.1 or 2 times the original. It is quite natural that

DO values in the upper layers (i - 1-6) did not change. DO values in the

bottom layers (see i - 11 and 12 in the figure), however, were significantly affected by the change in k values; i.e. the decrease (xO.1) in the rate of

SOD significantly improved hypolimnetic oxygen deficit and the increase (x2.0)

enhanced the deficit.

CONCLUSIONS

Based on the results obtained from lake surveys and in situ experiments

at the first stage of thermal stratification and analyses of DO profiles by a

simulation model, the following conclusions can be drawn:

a. The SOD rate demand was determined by in situ submerged chambers.

The rate per unit area was in proportion to DO concentration.

b. Rates of oxygen consumption in water decreased along with depth. The

rate in the bottom layer was only one tenth of that in the surface.

Rapid decrease in DO at the bottom layer was found to be due to high

SOD rate.

37
0-

0

#6 #12

S 0 .....

0

0

- 2.0Oxk

JUNE 1981

Figure 8. Effects of the change in the rate

constant of SOD on DO profiles

c. Although oxygen produced by photosynthesis was transferred by the

eddy diffusion into deeper layers, it disappeared at around the

middle layers and did not compensate for hypolimnetic oxygen

deficiency.

d. Remarkable restoration from the hypolimnetic oxygen deficit was not

expected by the control of phytoplankton production. The control of

SOD was found to be an effective restoration technique in Lake

Yunuko.

NOMENCLATURE

A bottom area of submerged chamber, m 2

c

"C, C A dissolved oxygen concentration, gwm -3

38
-3

C* saturation concentration of dissolved oxygen, g-m

Dip Dz eddy diffusion coefficient, m2 -hrD* reaeration coefficient, mohr-I

Hi thickness of layer, m

I, I 0 light intensity underwater and outdoors, pEinm-2" hr-I

k rate constant for sediment oxygen demand, m-hr 1

P specific rate of oxygen production, g 02 "g SS-hr

R specific rate of oxygen consumption, g 02.9g SS-hr

S suspended solid concentration, g"m

t time, hr

Vc volume of submerged chamber, m3

Ui specific heat of water, cal-g oC-I

z,. %ax depth and maximum depth, a

Swater temperature, C

P water density, kg-m-3

REFERENCES

i. Hutchinson, G. E. 1975. A Treatise on Limnology, Volume I, Part 2

Chemiscry of Lakes, Wiley-Interscience, New York.

• 2. Bates, M. H., et al. 1980. "Phosphorus Release from Sediment from Lake

"" Carl Black Well," Water Res., Vol 14, p 1477.

* 3. Gordon, J. A. 1977. "Reservoir Metaliunion Oxygen Demand," Proc. of

ASCE, EE, p 1001.

S4. Mcdonnell, A. J. 1978. "Field Estimates of Aquatic Plant Respiration and

"Its Application to Stream Dissolved Oxygen Budgets," Office of Water

Research and Technology, Washington, D.C.

39
4.,

5. Bowman, G. T., and Delfino, J. J. 1980. "Sediment Oxygen Demand

Techniques: A Review and Comparison of Laboratory and In-Situ Systems,"

Water Res., Vol 14, p 491.

6. Wang, W. 1981. "Kinetics of Sediments Oxygen Demand," Water Res.,

Vol 15, p 475.

7. Polak, J., and Haffner, G. D. 1978. "Oxygen Dopletion of Hamilton

Harbor," Water Res., Vol 12, p 205.

8. Fogg, J. B., and Fruh, E. G. 1973. "A Dissolved Oxygen Model for the

Hypolimnion of Lake LBJ," Interim Report 03, Department of Civil

Engineering, Center for Research in Water Resources, Univ. of Texas.

9. Schnoor, J. L., and Fruh, E. G. 1979. "Dissolved Oxygen Model of

Short Detention Time Reservoir with Anaerobic Hypolimnion," Water

Resources Bulletin, Vol 15, No. 2.

10. Dunst, R. C., et al. 1974. "Survey of Lake Rehabilitation Techniques

and Experiences," Technical Bulletin No. 75, Department of Natural

Resources, Madison, Wis.

11. Arai, M., et al. 1974. "Water Temperature - Hydrology 10" (in

Japanese), Kyoritsu Publ., Tokyo.

12. Sugiki, A. 1974. "Oxygen Budget in Running Waters - Water Pollution and

Its Control" (in Japanese), Gihoudo, Tokyo.

13. Japan Society on Water Pollution Research. 1982. "A Guide for Lake

Survey" (in Japanese), Kogai-Taisaku, Tokyo.

14. Canale, R. P., ed. 1976. Modeling Biochemical Processes in Aquatic

Ecosystem, Ann Arbor Science, Ann Arbor, Mich.

15. Aiba, S., et al. 1973. Biochemical Engineering, 2nd Ed., Univ. of Tokyo

Press, Tokyo.

16. Eckenfelder, W. W., Jr., and O'Connor, D. J. 1961. Biological Waste

Treatment, Pergamon Press, Oxford.

17. Dabes, J. N., et al. 1973. "Equations of Substrate-Limited Growth: The

Case for Blackman Kinetics," Biotechnol. Bioeng., Vol 15, p 1159.

"40
THEORETICAL CONSIDERATIONS OF GRAVITY DEWATERING OF DREDGED MATERIAL

THROUGH THE BOTTOM OF A CONTAINMENT AREA

T. Yoshida

Chairman of Technical Committee

Japan Bottom Sediments Management Association

15 Sankyo Bldg 7-12, Tsukiji 2-chome

"Chuo-ku, Tokyo 104, Japan

ABSTRACT

A pilot study utilizing short-term devatering

basins for dredged material was performed adjacent to

a dredging site at Lake Suwa. An outline of this test

was reported in this meeting by Nakamura. The study

was based on the newly incorporated idea of dredged

material dewatering by gravity d:ainage. The test not

"only had good results, but also created interesting

*• suggestions from the soil mechanics point of view.

This paper deals with the theoretical considerations of these test results, in which dewatering

"behavior is discussed from various points of view.

FUNDAMENTAL EQUATION OF WATER MOVEMENT IN SOIL

Considering a small element dx dy dz inside a nondeformable material, we

derive an expression of mass continuity for water as follows:

--

8Z dz

.- 7-

dv dw

'. dw _kdw +Kd w

dt I zdz 2 1 dz

S.

S.- 4 S.

/4
where

w - water content of dredged material

k -. vertical permeability coefficient of dredged material

.I K - diffusion coefficient of water particles in the vertical direction

*• We assume that the solution of Equation 1 is a separate function with respect

to t and z:

Sw = T(t) S(z) (2)

' Putting this into Equation 1, we get

V -klS1 + KS" T. -"s (3)

"2 "Here both sides are put to -n ,

T' 2 4 T -n )- 

mSts

S, + ns S 0 (5)

K K

"where

*

T - time function

S - function of z

"z - vertical axis (height)

S' - differentiation of S

S" - secondary differentiation of S

n - exponent of reduction

"" Hence we have

2

T C- n t (6)

"42
and

S(z) C2 e + C3e 2 (7)

+ /'il n2(8) -T -• I TK - T8

Finally the solution becomes

W - nt(ClemU 2 + C2 e ) (9)

Equation 8 is revritten as follovs:

4n2)

As the coefficient k is very small, the term is much larger than 1; that

I k 2

is, the value under - is negative.

Putting here,

a a n[ (10)

2

We have

- 2 i ± ia) (11)

Using this, we readjust Equation 9:

43
W *-nt ! - i) + C 2

•-n t+ kz (c :L k-i

•e 'Cie 2K u 2K +C + C2 2k /

2t kZ - k Z ak1

- (C3 Cosx Z+ C4 sin2K

-n2t+ kl 1 ak 2- A sin z (12)

(2K a

As a boundary condition we take

t 0, Z -, a W- 0

Then ve have

k

A =We H)

sin _ H +

A-We 2K

Hence Equation 12 becomes

n t L (H-Z) sin -Z + a

WH M 0 2KL (13)

sin ( - + a

From Equation 13 we can see that the vater :ontent decreases exponentially

vith respect to time and that it is distributed vertically in a function

multiplied by exponential and sine curves.

44
Here (Figure 1) we consider the fluid continuity expression for a bottom

di-ainage system.

H H-AH t t

ysFH fW( t_- 0) dz. ysFH AH w(t) z+ Et+ kFdt (4

i ~ ~ 0) dz B I f H - dz f +J fd 2Ft (4

00 0 0

where

F - cross-sectional area

H - initial depth of dredged material

e0 initial void ratio of dredged material

e - void ratio after t

ys - specific veight of dredged material

E - evaporation

k2 flux of fluid through the bottom filter

z

AHE

o

Figure 1. Bottom drainage system

Differentiating Equation 14, ve have the folloving equation, with the

thtl+e -H-All

assumption that 1 + 0 H

W ym(-n 2)e U2tHA (H-Z) sin 2 Z+

si k 2 a dz + E + k 2 0 (15)

0+e0 H 0 sin 1 -- H +

k2K

45
If we can assume here,

_n2t

E E 0

k = k2 (o)e0-nt

We can obtain the value of n , as a constant independent of time:

Sk(E + k2)(l - 0 + e0( + a) sin a (H 

n 2= W0YS -K (16) 2WoysK - 8

8 [i (H- AH) +a - coa- (HE •) +a]

k1

-e (sin a - a cos a) (17)

From Equation 16 we find that the value of n2 is proportional to the product

k1 (E + k 2 ); that is,

a 2 k1 (E + k2 ) (18)

The reason that bottom drainage exhibits a very quick dewatering lies in this

point (Figure 2).

From the test results, the values of n 2 are obtained as follows over an

interval of 2 days:

2n

No. 2 0.226

No. 3 0.293

No. 1 0.079

46
0 _ _ _ _ _ _ _ t

O2

-n2

W - Woe

W 2 small Slow

dewatering

n2 Quick

" large dewatering

Figure 2. Reduction of water content

TIME-DEPENDENT CHANGE OF WATER CONTENT

The changes in the water content in ponds No. 1 and No. 2 are shown in

Figure 3.

800

700

600

500

H •Upper layers 400.Lower layers No. I

300

No.2

200

:00

0

0 10 20 30 40 50 60

Time, days

Figure 3. Change of water content

As the figure shows, the water content decreases rapidly at the beginning

of the time interval and then slows after about 20 days. Therefore, the

47

S• , m m • •
time-cbange curve consists of two parts: rapidly decreasing and slowly

convergent.

It is clear that the former part of the curve is exponential and of the

n2t

form e , which was derived in the first part of this paper. But with the

decrease of water content, the weight of dredged material itself has an

effect; that is, the solid particles become consolidated. In a consolidated

state, Equation 1, which represents the movement of only water particles, is

no longer valid.

In this phase we must account for the change in water content caused by

consolidation. The hydraulic pressure of pore water is represented by the

following equation derived by Terzaghi:

au Cv ;2U (19)

at az2

k Es

Cv -1E (20) Yv

where

U - pore water pressure

Cv - coefficient of consolidation

k1 vertical permeability of dredged material

Es - elastic modulus of dredged material

yv - specific weight of water

Z d,

VAAW dzAu~,

dq

0 Z . ....-- 

The quantity of water per unit time per squeezed out element becomes

48
dq _ 2 dx dy dz (21)

As the decrease of water content AW is caused by this, then

aw k1 I2u - ys dxdydz - - dx dy dz (22) Yt az2

Hence

aN k1 a 2 u

=t YGTV 2 (23)

The solution of Equation 19 is as follows:

/ 2Uo , .. iz2

U 42U (1 - coo iw)(sin n-Ze4 (24)

i-i

Cot

where T - time factor - (25)

From Equation 2, we get the relationships between W and t

S2 v t

0 -• 4h 2 (26)

iII

This gives a flat and convergent curve. In practice, ve can replace it with a

parabolic curve for brevity of calculation (Vigure 4).

49
No.2, No.3

O000L Exponential

800 'Drainage.

600-

400-. | -Consolidation

b" Parabolic

200

0 10 20 30 40 50 60

Time, days

Figure 4. Change curve of water content

consisting of two parts

Figure 4 shows the curve of water content which is assumed as a combination of exponential and parabolic functions. The latter ir represented by the

following equation:

WaWd + (Td - t) 2 2f (27)

where

Wd - water content at the point of convergence

Td - interval time to the point of convergence

f - figure index of parabola

Using this equation for the measured values, we obtain the following data for

pond No. 2:

Wd - 251.4%

Td - 47.1 days

50
and for pond No. 3

Wd - 235.7%

Td = 54.3 days

As compared with these, the values of No. I become

Wd - 341%

Td - 50.5 days

BALANCE OF WATER QUALITIES IN POND

Z

H H-AH W l /

7 74Q2 (k2)

The above illustration is defined below:

Qa awater quantity which evaporates fcom the surface

Q2 a water quantity which flows out from the bottom

W - average water content after t

H a initial thickness of dredged material

AH - settlement

k2 a permeability of bottom filter

E - evaporation rate

Z n vertical axis

The equilibrium of water quantities is represented as follows:

51

m I mm I I I I I I | I I I I I II I I I II I I I I I I I I II I I II
YarY

+ysAHW0 ysA(H 1AH) " + Q1+ Q2(28)

where

A - cross-sectional area

W0 - initial water content

Ys - specific weight of solid

yw - specific weight of water

Since Q and Q are as follows:

t

Q1 f EAldt

"0

t

Q2 = EA dt

"0

We differentiate Equation 28

".-0- "" .. ysO( + ysW) - YsWYs dW .. ~ _ysW s d (L/A ++E- +k2 2 /A

"2 dt I I YsW dt 2 H ( +ysw)

"Hence we have

A F + yasw y ' •- (it (( + Yaw) 2 H- -dt 2 A2

If we put here

e yaw d (AH) 'AU _______ 1 + YsW dt - 2 d-

( + ysW) 2

52
We obtain

A1 AI

E A• e OR - (29)

"From this, the value of E at each time point can be calculated, if 0 and k

are known. An example of this calculation is indicated below:

t - 2 days

AH

0- .11

W = 7.92

0

d (-). 0.055 I/day (from figure)

dW --.

dt 2.265 I/day (from figure)

-1 sw d_ (_H\ ys dW

1+ysWdt U (1 yW) t

- 2.49 7.92 x 0.055 • (1 - 0.11) 2.49 X 2.265

1 + 2.49 x 7.92 2 7.92)2

I. +(.4I.9 x005+G 01)x226 + 2.49 x7.2-; 

, 0.0523 * 0.0117 - 0.064 I/day

"From the quantity of water which flows out from the bottom during 2 days, we

get

k2 6. 7 ...3 /day 0.0893 u/day "2 75 a.2

D."

A- 120 2

md

• " 53
A 165 2

A - 75 m2

""" ~165 7

"E T-8 0.064 x 126 - 8.93 75

120 120

E 0.727(8.064 - 5.581) - 1.80 cm/day

The change of evaporation obtained by the above-mentioned equation is indicated in Figure 5.

2.0

1.8

"1.6

1.4 I

• 1.2

0.8

0.6

0.4

0.2

10 20 30 40 50 60

Time, days

Figure 5. Evaporation

54
PERMEABILITY COEFFICIENT OF DREDGED MATERIAL

I

The terms u"ed in the above illustration are as defined earlier plus the

*' following:

Vv - water quantity inside settled volume

Vs - solid quantity inside settled volume

".- We have

"Vv + Vs - HIoA a

Then

rysVs ys AHsA - VW

Furthermore

H ( (30) to'sI

The balance of water quantities inside the settled volume is represented as

follovs:

d(Vv) (k+E (31) dt Ik )

Differentiating Equation 30, we have

"55
d =(A) dv v 1 + 1 d(Vv) dt ys w2dt) A + ysvJ A dt

yw 1 Vw 1 WVs I AH - Vw 1 - n

ys w2 A 2ii AH "-- -

Vw e ysv

Porosity n - I e - +

l÷•W

dt (1) dtYS ( )k H+ + E) I Ys d_t (32)

From this equation, we can calculate the value of kit because the values of

d_/_AH\ dv MH

d JAHN and d are measured. The change rates of F- are plotted in

Figure 6.

0.5 ............

0.4--.

0.3

H

0.2

0.1

0 10 20 30 40 50 60 70 80 90 100 days

Figure 6. Variation of EAs shown in Figure 7, the apparent permeability coefficient of the dredged

material decreases rapidly with time.

56
10-

.M 10-

N0 1

0 10 20 30 40 so 60

Time, days

Figure 7. Variation curve ofk

SHRINKAGE COEFFICIENT

Shrinkage coefficient is defined as follows!

AH AW

From the linear relationships between 'Hand AW, the coefficient Cs is

H

obtained. The relationships between then for our study art indicated in

Figure 8.

As the figure shows, the curve is not always straight. In the early

stage of dewatering it is nearly straight, but it is curved near the end of

the test. Therefore, it appears reasonable to induce the curved relationships

between water content change and shrinkage.

In this case, it seems that it is more practicable to us*eA instead of W

tiW.

57
10

9

* 8

a

S 6 1 -W

w

o S

/ 4

23

• No.32

•No.• 3

o 20 40 60 80 loot

1-AH

H

Figure 8. Relationships betveen 1 - --

and 1 - A

58
Figure 9 shows the relationships between the masured values of I -A

and I i

1.0

*No. I / 0.9

* No. 2, No. 3

:I 0.8

...•.0.4,•• - -- 0.6

0.4

- - - - +-0.6

0

0.4 0.5 0.6 0.7 0.8 0.9 1

AAH

H

Figure 9. Relationships 'et~teen

I - 'H and I - 0.3

Considering the convergence of the curve, ve assume the follovtng parabolic

relationship:

AH 2 A

Figre-. R"lati (33)

59
a W

b

H

The coordinates of a and b denote the point of convergence. We obtain the

following data for three ponds:

No. I a - 0.70 b - 0.31

No. 2 a - 0.60 b - 0.2

No. 3 a - 0.54 b - 0.19

DECANT POINT

Dredged material research in the United States suggested that the decant

point, defined as the water content at which cracks begin to develop, is

approximately 1.8 times the Atterberg liquid limit. The average water content

of the ultimate crust was suggested to be approximately 1.2 times the

Atterberg plastic limit. Our test results are examined from this point of

view in the following paragraphs.

Figure 10 shows the state of pond No. 2 after 7 days, when it began to

develop cracks at the surface. As the liquid limit of the tested dredged

material is 240 percent, the water content (which is 1.8 times this) is

430 percent. As Figure 11 shows, the water content after 7 days is 400 percent. Therefore, we can say that the decant point corresponds to a value of

about 1.7 times the liquid limit.

In Figure 11 it is seen that the water content converges to 240 percent.

That it, the average water content of the dredged material at the and of

60 days is nearly equal to the liquid limit. As compared with 0his, the

convergence point of pond No. 1 is 1.5 times the liquid limit (Figure 12).

60
Figure 10. Desiccation after 7 days

1200

S1000r

So

6~ 00

40

200 L.L

0

10 20 30 40 50 60

Time, days

Figure 11. Convergence of water content

of pond No. 2

61
1200

1000 No.1 Pond

800

600

400 _____ - - .5L. 1 . .. 1.5 LL

200

0

10 20 30 40 50 60 70

Time, days

Figure 12. Convergence of water content

in pond No. 1

CONCLUSIONS

In the management of dredged material, the most important matter is to

dewater the material as quickly as possible. Given such a necessity, our test

on bottom dewatering was conducted. Although dewatering by gravity drainage

has been investigated from the earliest days, practical applications of our

test seem rare.

It was found that dewacering of dredged material by gravity drainage is

very effective in lowering the water content within a short time period. We

have also learned much about the drainage behavior of dredged material from

the soil mechanics point of view.

62
RAPID DEWATERING TEST OF DREDGED MATERIAL IN SITU

M. Nakamura

Chief Engineer

Japan Bottom Sediments Management Association

15 Sankyo Bldg. 7-12, Tsukiji 2-chome,

Chuo-ku, Tokyo 104, Japan

ABSTRACT

The most popular method of reducing the volume

of dredged material is natural evaporative dewatering.

This method necessitates a long desiccation period of

about 10 months and a large space. Conditions like

these are difficult to overcome and the solution of

water pollution problems, especially in lake restoration. To impleuent pollution control projects it is

necessary to dewater dredged material as rapidly as

possible and to overcome the unfavorable conditions

mentioned above.

To meet these needs, a rapid dewatering test was

conducted in Lake Suwa. This paper reports the test

results.

OUTLINE OF TEST

The test was performed on the banks of Lake Suwa (Figure 1). The sediment, which was hydraulically dredged, was conveyed to the test ponds by a

branch pipe (Figure 2). To determine the differences between sun-dried and

bottom drainage ponds, three kinds of pond were conEZcucted as shown in

Figures 3 and 4.

Booster Pump Boat Branch D120"' d ea

~No I_ ... Floater V 

No.

Figure 1. Test site Figure 2. Conveying dredged material

63
40.500

3.0M S. M~ 3. 000 5.000 3. (W S. 00 3.00O

2.250 2.250 2.25 2.25, 2.21 2.2501

1.750 2. ý00 10.5SW 2.000 I 19.250

I I I I IJ

Figure 4. El ton ve. of t pn

No. a 3 fitratingmembran ~ad (polypoplene) atlll botman etcal e

II iN

Figure 3. Plan view of tesr ponds (meters) t

Mesh (hole

Witre. 2. Ormm diameter) Unwoven ,•m m Fabric Vinyl OO7mm

,.o<,! ,---,.oo ,.,,o I

I15 1.0 2.25 .• -3. _ _5.0 I.M t I0

5.000m

Figure 4. Elevation view of test ponds

Posed No. p was a conventional pond for sun drying, and Ponds No. 2 and No. 3 !.ad a filtrating membrane (polypropylene) at bottom and vertically set

membranes (polypropylene). Each pond had a surface area of 130 m , a bottom

area of 75 m 2, a volume of 234 m 3, and a depth of 1.8 m.

The side walls of each pond were covered by vinyl sheets to prevent

washouts. The bottoms of Ponds No.o 2 and No. 3 were provided with waterproof

sheets to prevent water permeating underground and possibly degrading

underground water. Gravel stones were spread on the waterproof sheets to a

thickness of 0.2 m to facilitate outflow of water (Figure 5).

64
4 mii t nJDWQX.p Fabric

Fabri

.. _--heet

Figure 5. Gravel layer

The bottom filter sheet was made of a polypropylene unwoven fabric. The

vertical membranes were of the same material, and served to promote the fall

of water along their surfaces. Pond No. 2 had three vertical membranes and

Pond No. 3 had five.

The layout of the test plant is indicated in Figure 6. The test material

was conveyed by a branch pipe and poured into ponds. To increase the permeability coefficient of the dredged material, flocculants (PAC and polymer)

were injected into the pipe at the point just before the pipe exit. Until the

dredged material slurry reached the prescribed thickness (1.5 m), excess water

was allowed to flow over the flashboard. The test began when the accumulated

thickness of sediment became about 1.5 m. The drain valve was then opened and

the drain water was pumped out through the reservoir pit. Quantities were

measured at prescribed intervals.

Overflow Piping from Dredge •:

Flashboard

Dredged MateriaJ/

Drain Valve

Pit Pump

Figure 6. Layout of test plant

PROPERTY OF DREDGED MATERIAL TESTED

Th.e property of the dredged material is shown in Table 1. A triangular

diagram of the soil is shown in Figure 7.

65
. • ':Y: T ..--"-- - .r•'7..'- S..... "" --. - - rr.:'l•: :• •:-- r •; r. •- -r -- -r . - .: ;- .- - r- r r "- -"• ;

TABLE 1. PROPERTY OF DREDGED MATERIAL

Pond No. 1 Pond No. 2 Pond No 3

Gravel (>2000•im), % 0 0 0

S"Sandy (74-200um), % I 1 1

" ' Silty (5-741,m), % 26 26 26

Clayish (<5), % 73 73 71

Max. size, mm 0.840 0.840 0.840

>1 Liquid limit, Z 237.7 245.0 239.2

ar Plastic limit, % 102.8 104.2 104.0

Plastic index 134.8 140.8 135.2

Specific weight, g/i 2,496 2,491 2,489

"Water content, % 1,'10 1,240 1,240

Unit weight, g/1000 cm3 1,050 1,032 1,032

Shrinkage limit, % 80 72 80

Compression index 2.18 2.29 2.45

"Dredged material

, o 

M() 0 u 2U 34, 4u W W 70 W

Silt (Sum - 74um)

Figure 7. Triangular diagram of soil

"As a clayish substance accounts for about 70 percent of the volume, the

"grain size of the tested dredged material is extremely small, and its liquid

limit is very high, indicating about 240 percent. The test results for such a

small material may not be applicable to other materials.

Since the soil condition is very unfavorable in this case, it is presumed

that much better results would be obtained for larger grain sizes.

66
"TEST RESULTS

Water Content

The variation in water content at the upper layers is shown in Figure 8.

"* The water content decreases rapidly within 10 days, and after that very

"slowly. There is a big difference between Ponds No. I and No. 2.

"For Ponds No. 2 and No. 3 we can say that dewatering is almost complete within 10 or 15 days.

1200 i

1000

800

600

S~No.2 Pond

200 Pond

0 10 20 30 40 50

Time, days

Figure 8. Variation of water content

"Settlement

The change in settlements due to shrinkage is shown in Figure 9. The

difference between sun-dried and bottom-drained ponds turned out to be more

than just water content. We can also see a difference between Ponds No. 2 and . No. 3. The pond with five vertical membranes displayed larger settlements

". than the pond with three membranes. In Pond No. 3, the settlement was almost

* complete in 30 days.

67
4 Time, days

0 1o 20 30 40 50 S 0 70

.4.

1-0-: No.1

o-- No.2

30-

40,

60

Figure 9. Variation of settlement

Drainage Water Quantities

Water quantities which flow out from the bottom change with time as shown

in Figure 10. This figure shows that most of the water contained in dredged

material has drained in about 10 days.

50

Po.1fndý

30

Time, days

Figure 10. Variation of drainage water

Desiccation Cracks

With the advancement of drainage, desiccation cracks begin to develop.

"As the liquid limit of the test material is about 240 percent, the

corresponding decant point (1.8 times) becomes 432 percent. This point comes

68
after 7 days in Ponds No. 2 and No. 3 (Figure 11). It has been observed that

surface cracks begin to develop at this time.

1200

1000

800

600

400 No.1 Pond

No.2 Pond

200 No.3 Pond

0 10 20 30 40 50

Time, days

Figure 11. Decant point

There was a large difference between sun-dried and bottom-drained ponds.

Figure 12 shows crack development in Pond No. 2 after 13 days, and Figure 13

shows crack developmrnt in Pond No. I after 27 days. In Pond 2 well-developed

cracks are observed waiie Pond No. I has no cracks. After about 10 days, the

surface of Pond No. 2 was hard enough to stand on. However, even after

2 months, one could not stand on Pond No. 1.

Soil Property After 2 Months

The compressive strength qu of the desiccated polygon after 62 days is

"* shown in Table 2. I

The consolidation test results of the polygon are indicated in Table 3.

* As shown in these tables, the desiccated dredged material can easily be

* .handled by clamshells and transported by dump trucks.

Vertical Distribution of Water Content

The vertical distribution of water content in Pond No. 2 is shown in

Figure 14. The curve after 11 days is nearly straight, but the curves after

' 34 and 48 days are completely straight.

Such results arise necessarily from the fact that desiccation cracks

reach to the bottom at some time interval after 11 days but before 34 days.

69
"""*

Figure 12. Crack development after 13 day

(W 4 300%) in Pond No. 2

Figure 13. Appearance after 27 days in Pond No. I

(W - 450%)

70
TABLE 2. COMPRESSIVE STRENGTH OF DESICCATED POLYGON

Depth qu W

Pond Point Layer* cm kg/cm2 %

A U .... 343

No. 1 L 339

B U .... 403

L 340

A U 24 0.162 221

No. 2 L 48 0.106 256

B U 24 0.160 239

L 48 0.148 263

A U 24 0.179 219

No. 3 L 48 0.116 251

B U 24 0.174 233

L 48 0.168 243

* U - Upper layers, L lower layers.

TABLE 3. CONSOLIDATION TEST RESULTS

Pond No. I Pond No. 2 Pond No. 3

Yielding

point, kg/cw 2 0.16 0.163 0.214

Compression

index 1.66 1.70 2.20

Coeff. of 1.70 x 10i 163 x 10 1.92 X 10-1

consolida- - 7.02 x 101 - 6.58 x 10-1 - 5.63 x 10-1

tion, cm2 /min

Coeff. of 9.82 10- 2 9.36 x t-2 9.18 x 10- 2

volume com- - 5.03 x 10- - 5.43 x 10- 1 5.94 x 10-1

pressibility, cm2 /kg

In comparison, the curves in Pond No. I are not straight, indicating high

contents in upper layers and low contents in lower layers (Figure 15).

The reason the water contents in the lower layers are unexpectedly low

lies in the fact that some quantities of drained water have permeated

underground.

71
Water Content, %

100 200 300 400 500

10

20 04

30

• 40 Pond No.2

50

S60

2 70

Z80

90

100

110 t48 days tol1 days

t-34 days

120

Figure 14. Vertical distribution of water

content in Pond No. 2

Water Content, %

100 200 300 400 500 600

0

10

20

a30 Pond No.1 I

u o I in-34 day toll =114ddys days

40

50I

60 40!

70

80

90 I

100

110

120

Figure 15. Vertical distribution of water

content in Pond No. 1
Water Quality of Drainage

The quality of water which is ei.hausted from the bottom is shown in

Table 4. At the beginning of dewatering, the drainage water had some

suspended solids, but after 24 hr it became very clean.

TABLE 4. WATER QUALITY OF DRAINAGE

Pond No. 2 Pond No. 3

Concentraticn Concentration

Hour of SS, mg/_ of SS, V L

0 100 28

1 24 14

6 20 8

24 4 3

30 3 2

48 2 2

CONCLUSIONS

As mentioned before, we have obtained unexpectedly good results in our

tests. The concept that water in dredged material should be drawn out by

gravity was verified by the test.

In our country, there are many cases in which dredged material must be

placed in ponds temporarily and after dewatering transported to final disposal

sites. For such cases, the bottom drainage method is very effective because

large quantities of dredged material can be treated in small ponds.

Although the basic points regarding this method were explained, there

remain several points which bhould be improved for practical application.

73
MECHANICAL DEWATERING OF DREDGED SLURRIES

Paul R. Erickson and Joe Hurst

Rexnord Inc.

5101 W. Beloit Road

P. 0. Box 2022

Milwaukee, Wis. 53201

ABSTRACT

Over the last 5 years, significant developments

have occurred in dewatering; belt press technology,

computer finite element modeling for structural design, improved high molecular weight preconditioning

chemicals, and advaniced belt weave and strength

characteristics have all been key factors.

A 2.5-m-wide heavy duty belt press can dewater

high density sludge at a rate of 20 to 30 tons/hr (dry

basis). The unit is the largest factory preassembled

module, and thus is transportable from site to site.

It can be mounted on a concrete slab, truck mounted,

or mounted on a barge to eliminate dredge-to-shore

pumping and piping problems. Energy required for

dewatering is equal or less than current energy levels

expedient when pumping from dredge to shore. We anticipate that an 83 percent volume reduction would occur

when converting a 15 percent solids dredged slurry to

a 70 percent solids cake.

Near term, belt press dewatering may especially

fit into dredging operations where confinement is

necessary or where chemical contamination is present

in the dredgings and total solids capture is necessary. Final cake may be placed directly into berm or

dike construction, or, where chemical contaminants

build up significantly, chemical fixation is feasible.

INTRODUCTION

Numerous dredging techniques are in use today, many of which are site

specific (1). Our approach over the years has been directed to the field site

as well. Therefore, the programs described herein cover an "enviroenergy"

spectrum and touch on subjects from bench scale work up to large volume, continuous processing. Application of this technology must be tailored to the

site to provide the most expedient and cost-effective solution.

74
BACKGROUND

Through the early 70's, vacuum filtration was the dominant process for

sludge dewatering. Centrifugation was emerging as a preferred process in some

applications. Also, the batch-continuous filter press was making first appearances in the municipal sludge dewatering field in the United States. This

field has always been confronted with conservatism, some justified because of

the wide variation in sludges and some just typical of operation and maintenance. When by the mid 70's the energy crisis took its full toll, "traditional thinking" was overshadowed by the thought that we could no longer

direct 40 percent of the plant energy to sludge dewatering and management.

Thus, during the mid 70's the filter belt press emerged because it required

only one fifth the energy of the vacuum filter. Further concern over

available landfill and agricultural spreading created an incentive for volume

reduction, and organic polymers rapidly replaced the voluminous chemical

conditioners lime, ferric chloride, ard alum. Finally, new, high-rate batch

continuous filter presses held the prciise of dewatered cake solids levels

suitable for incineration without addition of auxiliary fuel.

Any review of available literature on dredging technology reveals that

the concept of applying "state of the art" mechanical devatering is not

new (2). In the mid 70's there were advocates of mounting vacuum filters on

barges while others claimed economics were prohibitive. Concurrently, some

concern developed over migration of toxic or hazardous chemicals, possibly

associated with the finer portions of the particulates, conceivably lost in

the filtrate. Thus. it seems that the subject of mechanical dewatering for

dredging has not been pursued aggressively for several years.

During this time, belt press technology progressed rapidly in mechanical

design; for example, now there are reliable tracking systems and structural

design of rolls and main frame by computer (finite element) modeling (3).

Belt strength anid weave technology have improved rapidly, achieving longer

lifel a broad selection is now available for filtration variability. Also,

through use of polymer chemistry--high molecular weight cationics are constantly improving. For example, earlier dredging dewatering investigations (4) concluded that original polymers were ineffective for high concentration slurries (10-20 percent) because the polymer could not be completely

dispersed to all the fines; thus, fines not treated chemically were not captured. Now, polymer is routinely injected 10 to 20 pipe diameters upscream of

the distribution head box when handling feed slurries concentrations as high

as 40 percent solids.

Our own experience confirmed rejection of the mechanical dewatering of

dredgings via vacuum filtration. When we first replaced filters with belt

presses in a major plant in Wisconsin, the existing vacuum filters were capturing only 50 percent of the solids; the fines wore sent back to the head end

of the plant. This inventory of solids buildup had the entire biological

plant process in extreme jeopardy. Our prototype belt press demonstrated 98

to 99 percent solids capture; within 6 months the filters were completely

abandoned in favor of belt presses. The refractory solids inventory was

eliminated and the biological process efficiency restored. Once the "fines

inventory" dropped out of the system, the plant found it relatively easy to

75
dewater sludge, and chemical costs dropped off. These presses have been

performing continuously for 3 years (5).

CURRENT DEWATERING PROGRAM

While our early efforts were directed toward lighter organic, biological

sludges, it was evident from work for Rexnord's Gundlach Coal Division that

the belt press was solving the problem of coal tailings and pipeline slurry (6) dcwatering. It also occurred to us that the earlier organic press

efficiencies could impact clean coal dewatering where vacuum disk filters were

being used. The capital cost of commercial sewage sludge belt press units was

being paid off in 2 years in savings from existing vacuum filters operation

and maintenance costs. Thus, we rapidly accumulated bench field data at a

number of eastern U. S. coal sites, and from two availab.e coal pipeline

slurry sites. A tabular summary of coal characteristics is included in

Table I and, as expected, a wide variability in clay, pyrite, and coal content

and particle-size distribution exists. Using the two-phase bench testing process shown in Figures 1 and 2, the following selections were made:

a. Optimum polymer selection and dosage.

b. Feeds solids residence time for removal of free drain and pressure

water.

c. Solids capture rate of upper deck and lower pressure roll water.

d. Cake solids concentration.

e. Cloth media selection to ensure proper cake release.

f. Alternative treatment strategies for capture of filtrate solids where

water recovery and/or total solids confinement are necessary. (Clarified or filtered filtrate water can be reclaimed for belt wash

water).

For dredging bench work where contaminants are present, concentrations

can be measured in the amount reporting to the cake phase versus the filtrate

phase. Also, cake volumes can be scaled up and matched to available storage

areas. This avoids some uncertainty in predicting the rate of slurry compaction and volume required for long time storage service life for conventional

impondment.

These test runs are developed from five 50-gal sample sizes and, armed

with rule of thumb scale-up, belt press economics are defined and compared to

alternative solids handling strategies. Considering feed sample variation,

test results are completed in a week or less. Figure 3 illustrates typical

coal tailingr feed, filtrates, and cake.

With the field test feasibility program completed, the major design and

application criteria were known and we could design and fabricate the fullscale unit. Figure 4 illustrates the basic size module, a 2.5-m-wide unit,

the largest fully factory assembled, transportable unit possible. Figure 5

illustratas a separate upper expanded drain deck, frequently needed because

76
- a

5--- 0 o 90 2 2

-0 9 -- 8_ ,

* . .•

S ;•

* C7

"" • , 2, i 
Figure 1. Bench test setup, Phase I

Figure 2. Bench test setup, Phase II

78
Figure 3. Typical bench test samples of coal tailings--feed,

filtrates, and cak&

Figure 4. Factory-assembled '.5-rn-wide

belt press

79
.7-

oV

"Figure 5. Upper expanded drain deck

the incoming slurry may be dilute in che 8 to 15 percent solids range where

hydraulic loading governs. The upper deck also serves as a buffer or cushion

to even out some feed variability before the slurry enters into the pressure

"section. When water is extracted on the upper deck, better solids "entrap-

"ment" occurs; hence, a higher overall solid capture is achieved versus pressing out loosely bound water. The high rate of water extraction permits the

lower deck and pressure rolls to perform at higher solids loading rates, in

some cases over 30 tons/hr (dry basis). Dewatering proceeds and a "barely

pumpable slurry" is formed in the wedge section. (In dredging one may elect

to stop the process at this point and still pump the solids from the barge or

"shoreline confinement, or proceed into the pressure rolls and produce a dry

haulable cake, suitable for landfill compaction with standard earth-moving

equipment). Dry cake is che objective in dewatering coal tailings refuse;

i.e., the raw refuse at 10 percent solids, thickened if necessary to 30 percent solids, is concentrated on the upper deck to 50 percent solids with final

cake formation through the press at 70 percent solids average, or 75 percent

solids maximum.

In June 1983 the prototype was prepared for field testing and shipped to

a coal mining and cleaning plant in the eastern Kentucky field. Figures 6

and 7 illustrate shipment, arrival, and installation of the unit. With factory assembly and modular shipment, the unit can be operational within days

and readily moved fr-m site to site. Figures 8-10 illustrate dewatering of

"coal tailings at the 30-tons/hr (dry solids basis) rate. Tests on sustained

production are under way at this time.

80
Figure 6. Shipment of 30-ton

belt press

i~

Figure 7. Field installation of press f or coal

tailings dewatering

81
h Figure 8. Dewatering of tailings at 20 to 30 tons/hr

Figure 9. Closeup of coal tailings cake at 70 percent solids content

82
Figure 10. Tailings cake discharge and loading bunkers

WHY DEWATER DREDGE SLURRIES?

Economic justification of dewatering concerns:

a. Volume reduction versus handling, piping, hauling bulk liquid, or

lagocning.

b. Moisture extraction. Any thermal process will be energy intensive if

wateýr is not extracted.

For dredging, volume reduction is the obvious potential justification.

Using available coal tailings dewatering data, as it is reasonably comparable

to some dredging characteristics, Figure 11 demonstrates specific volume

reduction economics.

For example, a raw feed of coal tailings or pumped dredged material at

15 percent solids would represent a volume of 180 cu ft (5.1 cu m). Upper

drain deck dewatering would achieve a solids concentration of 50 percent

solids with a volume of 48 cu ft (1.4 cu m). Finally, roll press section

dewatering would develop a stabilized cake solids concentration of 70 percent,

and a final volume of 31 cu ft (0.9 cu m).

83
VOLUME VOLUIE

LITRIES ALLOS FEET ETHES

" 3"0.

RAW I00 4zý FEED .100

- 1 - 40 1.4

- FINA CAKE .1".

S I"..- - _ .510.4

S0 is 38 3 40 30 7TO

PERCENT 306.10

Figure A1. Slurry dewatering, slurry volume versus

percent solids

Thus, volume reduction ia as follows:

180-48- 12 - 73 percent through free drain deck (1)

180 180

48-31 17 48 - 1 35 percent press section dewatering 48 48 (2)

180-31 149 180 - - 83 percent. overall volume reduction 180 180 (3)

Because the greatest volume reduction occurs in the free drain section, one

might question the economics of complete cake formation. First, the polymer

chemical preconditioning costs will be the same with or without the roll press

section, at 50c to $1.00/ton (dry solids basis). Second, the ultimate dredge

solids fill location probably requires spreading and compaction or use as berm

or dike material; hence, a drier cake for handling and hauling is necessary.

Third, the drier cake will resist reliquification from rainfall; thus, erosion

or leachate migration will be minimum. Revegetation is more likely to occur

in one growth season or sooner.

Further investigation is necessary to establish where the on-barge dewatering and 83 percent volume reduction is cost-effective versus current

practices of pumping or barging the slurry to shore, developing extensive

impoundments, and accounting for proper environmental assimilation of the

effluent, or significantly extending available dredge fill area capacity. The

application in which the barge-mounted belt press concept may be near term is

84
in the area of total confinement of dredging containing toxic and hazardous

materials.

Currently, dredging operations maintain 25,000 miles of U. S. channels

and 1,000 harbors (7). This develops 250 to 300 million cubic yards of

dredged material that must be properly reincorporated into the environment

annually. Further it is estimated that 20 percent of the dredged material

contains chemicals of concern and special confinement measures should be

incorporated. Thus, 50 to 60 million cubic yards, say 55 million cubic yards,

if dewatered and confined using a belt press system, would reduce the volumes

to 9.5 million cubic yards.

Assuming 250 days/year operation, the 55 million cubic yards translates

to 44.5 million gallons per day. Based on a 2.5-i unit capacity of 400 gpm

and 1000-minutes/day operation and 20 to 30 tons/hr (dry solids basis),

approximately 100 units would be necessary. Assuming that some sediment would

not properly respond to belt press dewatering (as prechecked via bench test)

the area of appropriate application may cover one half of the dredging sites

where a chemical contamination exists within the sediment.

From an overall problem-solving point of view or investment in resources,

sludge dewatering belt presses for U. S. muncipal treatment plants are being

installed at a rate of 80 per year. Thus, by comparison, 50-100 belt presses

for dredging applications are similar in magnitude.

It has been well documented by researchers that any chemicals present in

sediment are complexed and asaociated with the finer particulates (8). Thus,

higher belt press solids capture is necessary for total confinement. Experience to date with coal tailings shows a 98 percent plus solids capture rate.

Polymer dosage rates are normally set such that a slight excess of polymer is

used to sustain prop-r performance. This excess polymer selectively associates with the finer particulates that pass through the belt media. Repeated

testing shows that these filtrate solids agglomerate and separate out in less

than 30 min. Thus, filtrate clarifier effluent is reused as belt washwater

and the balance may be discharged directly to the receiving stream within discharge standards. The polymer-enriched filtrate solids settle out to 5 percent of original volume and are pumped directly to the upper drain deck and

reintroduced with raw slurry. Thus, confinement is complete.

Figure 12 illustrates the conceptural barge-mounted belt press systems.

Dewatering has been incorporated into a dustpan or cutter head barge as these

are the "real workhorses of both private and Federal dredging fleets" (1).

Obviously, the system could be adapted to pneumatic dredging for deeper harbor

dredging as perfected and practical in Japan (1). Note that the barge receiving the dewatered cake would be sized to receive an 18-hr cake production, or

360 to 540 tons (dry solids basis). Energy for the dewatering system would be

20 hp (exclusive of pumping). This is probably equal or half that currently

used to pump the slurry from barge to shore.

An alternate to the barge-mounted concept may be an on-shore dewatering

facility using the "mudcat" type dredge, positioned at or near the final landfill site. Thus, slurry would still be piped to shore. Whern space is too

limited for slurry impoundment and long-term separation, the 83 percent volume

85
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c£ , '

I I

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... =

00

*4. U

c 0 v

Q -- IL I U

,~I •.. .1 L+-""

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86
reduction and immediate production of a high quality filtrate would satisfy

environmental concerns. The dewatering system might be truck mount,-, to

facilitate shorter slurry pipe transport distances, e.g., relocating parallel

to a river dredging operation, week by week.

DEWATERING IMPACT ON CONTAMINANT CONCENTRATION

The chemical contaminant concentrations present in the dredgings will

increase as dewatering proceeds. For example, if cadmium were present at

10 mg/i ii the pumped 15 percent solids slurry. the following example at a

400-gpm treatment rate is appropriate:

a. Hourly processing rate is 24,000 gal or, at a specific gravity of 1:1

and 15 percent solids, the total weight is 220,000 lb/hr, containing

33,000 lb solids per hour (throughput of 16.5 tons/hr).

b. Assume 10 mg/1 cadmium is presenc, or 2.2 lb 'admium.

c. Final cake concentration is 70 percent solids, or 21 000 gal water

was removed per hour, or 47,000 lb total weight remain as cake per

hour.

220,000 orig.

d 47,000 rimagn.ng x 10 mg/i - 46.8 mg/i cadmium present.

Thus, the heavy metal content is increased and further treatment of tht stabilized cake may be necessary for permanent environmental compatibility.

DEWATERED DREDGING HANDLING AND PROCESSING ALTERNATIVES

After achieving an 83 percent volume reduction and a 70 percent stabilized cake, several alternative management practices may now be economical.

Dike material

The dewatered dredge cake can be used immediately for dike material to

provide additional storage capacity (8). Here a split barging system could be

used, where dewatered cake could be barged to form the dike and then slurry

could be piped to the diked area.

Chemical fixation

Two-part chemical fixation--cement followed by sodium silicate--offers

permanent encapsulation and pH stabilization for a wide range of contaminants,

at high concentration. This fixation process is in full-scale practice for

drilling muds, sewage sludge, and refinery sludge. Economics are directly

proportional to volume treated. Thus, dewatering plays a vital role in

achieving economical operation. In some cases, chemically fixed dewatered

dredged material may form the barrier walls and bottom liner and dewatered

unfixed solids could be contained. As an alternate, unfixed dewatered solids

would be spread and a portion of the solids would be fixed and used as a

capping, barrier protection at the end of the day.

87
Then longer range, high rate uptake biomass crops such as hyacinth or

cattails or new mutant woody species would be harvested and assayed until contaminants in the cell tissue dropped to safe environmental levels. Toxic

metal uptake into wetland plant biomass (cattail and willow) has been documented in several contracts with the Federal Department of Transportation.

These projects sought to determine effects of highway stormwater runoff pollutants (metals, hydrocarbons, salts) on receiving water ecosystems. Metals concentration factors between sediment/soil, and vegetative components such as

roots, rhizomes, shoots, stems, and leaves were determined (9).

CONCLUSIONS

Current practices in belt press coal dewatering suggest that similar success can be achieved on a portion of dredgings extracted from U. S. rivers and

harbors. Combinations of advanced technology in computer structural modeling,

high molecular weight polymers, and improved filter belt life are now available for the filter press process.

Near term application may exist for dredged slurries contaminated with

chemicals because:

a. Volume reduction up to 83 percent would permit more positive control

and confinement of the dewatered cake in designated landfill areas.

b. Containment of the chemicals within the solids and direct discharge

of the filtrate is possible.

c. Reduction of a portion of the 55 million cubic yards to 9.5 million

yards may accelerate the rate of dredging at reduced cost.

The 2.5-m modular belt press can be applied to a number of site-specific

dredging scenerios:

a. Adapted for off-shore barge-mounted systems, for dustpan, cutter

head, or deeper pneumatic dredging.

b. On-shore, semifixed where an immediate dike or berm formation is

required.

c. Truck mounted, with week-to-week movement paralleling river dredging.

d. Confined, shallow mudcat type dredging and dewatering.

Specific bench test technology has been developed to define the proper

site-specific applications.

Volume reduction achieved by dewatering can then add certain options to

the overall dredging management program:

a. Chemical fixation where necessary.

b. Prolonged fill life of existing adjacent impoundment areas.

c. More immediate seasonal cropping or revegetation.

88
REFERENCES

1. The Feasibility of Dredging for Bottom Recovery of Spills of Dense

Hazardous Chemicals, Rand and Ford, Corps of Engineers; 1978 National

Conference on Control of Hazardous Material Spills.

2. Investigation of Effluent Filtering Systems; Report D-76-8, August 1976;

Appendixes C and D; Vacuum Filtration and Belt Systems.

3. Predicting Loads for Belt Press Application, Rexnord Corporate R&I;

Crandall, Raske, and Fries, 1983.

4. Investigation of Effluent Filtering Systems; Report D-76-8, August 1976;

page D5.

5. Better Dewatertng Improves Sludge Recycling; June 1981, Thomas J. Bunker,

Asst. Mgr. Racine Wis. Waste Water Utility (Published in Water Engineering &

Management).

6. Optimizing Slurry Dewatering; March 1983, Pietila and Rooney; Rexnord EETC

8th International Conference on Slurry Transportation, San Francisco, Calif.

7. U. S. Army Corps of Engineers, Dredged Material Research; Vol D-81-2,

August 1981, p 2.

8. Guidelines for Designing Operating and Managing Dredged Material

Containment Areas; Report DS-78-10, December 1978, pp 3 and 13.

9. Effects of Highway Runoff on Wetlands; Rexnord EETC Volume A: Research

Report; Preliminary Draft Report Submitted to National Research Council;

February 1983.

89
DISPERSION OF SEDIMENT RESUSPENSION

CAUSED BY DREDGE OPERATION

Hiromi Koba

Japan Dredging and Reclamation

Engineering Association

2-8, Toranomon 1-chome

Minato-ku, Tokyo, Japan

ABSTRACT

As a working model of dispersion of sediment

resuspension caused by dredge operation, a model of

turbidity levels according to distance from the dredge

is useful. The level of turbidity near the sea bottom

is estimated to be 5 ppm at a distance of 100 m and

3 ppm at 200 m from the dredge. Also, the level of

turbidity near the water surface never exceeds that at

the sea bottom. Therefore, it is not believed that

dredging work will make a wide area of the sea turbid.

INTRODUCTION

Dredging work is indispensable in the excavation of waterw-v° and the

construction of harbors. However, dredging work causes sedime isuspension.

Whether or not the resuspension develops turbid seawater on a large scale has

not been proven. If the turbidity is dense and long lasting, it might endanger the life of fish and seaweed. It is desirable to predict the existence of

this threat by analytically determining the dispersion of sediment resuspension caused by dredge operation; howcser, the present level of technology

falls short of this goal. Therefore, the measured data taken from actual

dredging work must be used in these predictions.

The following three companies belong to the Japan Dredging and Reclamation Engineering Association and each have agreed to make observations relative to the dredging work of one of their recent projects:

a. Penta-Ocean Construction Co., Ltd.

b. Toa Harbor Works Co., Ltd.

c. Toyo Construction Co., Ltd.

The results of their observations will be published as a technical paper

in the near future, but the writir will give some thought to the problems by

referring to the unpublished reports (1-4) with approval of the three

companies.

90
Bottom sediments in these dredging works were not toxic; however, their

research findings may still be of use in dredging toxic bottom sediments.

NATURAL CONDITIONS OF THE DREDGING SITES

Table 1 describes three dredging projects chosen for observation by the

three companies. The locations are shown in Figure 1.

TABLE 1. DREDGING PROJECTS

Project Purpose of Nature of BotNo. Location Work tom Sediment By Order of Contractor

1 Imari Bay Anchorage Clay Saga Pena-Ocean

renovation Prefecture Construction

Osaka Bay Digging of Silty clay Osaka Toa Harbor

(Hannan Port) reclamation Prefecture Works

3 Osaka Bay Quay base Clay Osaka City Toyo

(Osaka Port) construction Construction

All of the dredging sites are located in close sea areas with mild tidal

currents and low permanent currents. Figure 2 shows the tidal currents in

Imari Bay and the site of dredging project No. 1. There are two mouths to the

bay, east and west, and the current flows from the west mouth tc the bay

interior and to th.e east mouth at rising tide, and vice versa, at falling

tide. Overall, current directions are complicated by the influence of the

topography. The current speed is as low as 10-17 cm/sec on .he upper stratum,

and at most 5-15 cm/sec on the bottom stratum.

Dredging projects Nos. 2 and 3 vJere conducted in the eastern part of

Osaka Bay where the tidal current is as low as 25 cm/sec or lower and the current directions vary greatly according to the day. The only exception is when

the tidal current passes the mouths of the bay. Otherwise, the current velocity is constant as shown in Figure 3.

Most dredging projects in Japan occur in a tidal current similar to those

in Imari and Osaka Bays. In those sea areas, the dispersion of the substances

is likely to be strongly affected by unpredictable flow velocity. Therefore,

a theoretical treatment of dispersioa is out of the question, and only a

deduction through probability based upon the measured values is possible.

The grain-size characteristics of bottom sediments at the dredging sites

are shown in Table 2. They are predominately clay and are easily suspended in

the water column when disturbed.

91
N

Dredging Project No. 1

Dredging Project No 2 0 3O0km

Figure 1. Locations of dredging projects

3 hr aftif

high tide

(dur1tion of

fall)

iure 2. Tia ur ns n____

Kiurokawscho

StwSesoi area

-upe tratum.ý

0 1 2 3km

Figure 2. Tidal currents in

Imari Bay

92
HVogo Prof. Av,

Arnegasaki

Dredging Project

/ No.3

0-S

S• Osaka

0.1 - -

-.. /

s. k

0.4, \ 'wl" ., \\ er.

0..2

-- S

0-1.

/ r/ Takaisl.

00

0 Skm

/ o .. '

/twimeano_____

Tidal currant Un!t: knots

Figure 3. Tidal currents in the eastern part of the Osaka Bay

where current is the strongest

TABLE 2. GRAIN SIZE OF THE BOTTOM SEDIMENTS

AT THE DREDGING PROJECTS

Under Under

Project No. Location 0.075 mm, 2 0.005 mmp_2

I Imari Bay 94.5 47.2

2 Osaka Bay 58.3 26.6

(Hannan Port)

3 Osaka Bay -- 55.6

(Osaka Port)

93
SPECIFICATIONS OF THE THREE DREDGING PROJECTS

Outlines of the dredging projects are shown in Table 3.

TABLE 3. SPECIFICATIONS

Parameter 1 2 3

Dredging period Oct '82-Mar '83 Sep '82-Jul '83 Aug '82-Jan '83

Observation time Jan '83 May '83 Nov '82

Dredge D-3,000 PS D-4,800 PS D-4,000 PS

Total soil

volume, m3 636,380 730,571 551,800

Dredging depth, m 5.0-8.3 11.0-12.0 12.0-18.0

Dredged sediment

thickness, m 1.0-2.0 1.7-2.6 0.5-2.0

Pumping volume,

M 3 /hr 5,600-6,300 9,100-9,600 4,500-5,700

"Cutter

revolution, rpm 12 17.6 16

Swing speed, m/min 8,12,18 4.4-6.1 4-21

Swing distance, m 80-90 82 56-85

"Note: Values for dredged sediment thickness, pumping volume, cutter revolution, swing speed, and swing distance represent those at the time of

turbidity observation.

TURBIDITY OBSERVATIONS AT DREDGING PROJECT NO. 1

Dredging project No. 1 was slated to dredge 636,380 m3 of bottom sediment

in about 6 months. Turbidity observations were conducted during 4 days of

actual dredging. As shown in Table 4, the afternoon hours of each day were

"spent in observation. During these 4 days, six observation cases were

planned, each case being slightly different from the others in the dredge

operating conditions. The time spent for each case was 1.0-1.5 hr. The differences of the operating conditions were in the swing speed and the dredged

sediment thickness.

The operating time of a dredge consists of two alternating periods: the

dredging period in which the dredging by cutter takes place, and the advancing

94
TABLE 4. OBSERVATION SCHEDULE

Date Observation Case and Time

Jan. 18 B-1(14:17 to 15:47)

Jan. 20 A-1(12:56 to 13:56) B-2(15:43 to 16:43)

Jan. 21 A-2(14:51 to 16:21) B-3(17:03 to 17:43)

1Jan. 22 B-4(16:14 to 17:14)

i period in which no dredging is conducted but spuds are driven. Each observation case was scheduled to cover at least three consecutive dredging periods.

From among the many items observed, two are discussed herein: measurement of turbidity in the vicinity of the cutter, and measurement of the turbidity dispersed into the sea around the dredge. In the vicinity cf the

cutter, the measuring stations are fixed at the tip of the ladder with a

frame, where the turbidity meters are set, as shown in Figure 4. In each

observation case, the turbidity was measured six times during the dredging

period. The average of the measured values taken at each station is as stated

in Reference 2, of which the maximum was 1,313 ppm. Considering that this was

the average value, the turbidity in the vicinity of the cutter could be said

to have been quite high.

" •~C F a O:turbidity

%

% A : watr temperature and depth

I3.

Figure 4. Locations of measuring station

For the measurement of the turbidity dispersed into the sea around the

dredge. Figure 5 shows the positions of the measuring station. In each case,

two small boats circulated around the 18 stations shown in Figure 5 and measured the turbidity at each station using a meter thrown into the water at the

95
loom 50 so 50 s 50 100

2 3

J I , II middle$ /

.1 1

7 8 9 1 I 0d 0 7

0-

44 .:36-46

so 090

SW~eg S -1: 3000

1717 I

Figure 5. Locations of measuring stations (Dredging

Project No. 1)

different depths. One circuit of the 18 stations by the boats took about

20 min and three circuits were made in each case.

For the purposes of this study, the measuring stations were divided into

three groups according to the distance from the dredge. Stations 8, 9, 11,

"12, and 13 were ne'rest to the dredge and compose Group A. The distance of

each from the dredge is about 50 m. Group B contains stations 4, 5, 6, 7, 10,

14, 15 and 16, all about 100 m from the dredge. The remaining stations, 1, 2,

3, 17, and 18, belong to Group C, and are about 200 m from the dredge.

Table 5 shows the results for the three groups. Turbidity is shown by

parts per million, representing suspended solids value, which is the value

reached by deducting the estimated backgrounc value from the measured value.

Comparison of these values with those in the vicinity of the cutter shows how

the dispersion has decreased the turbidity.

IIt can be seen from Table 5 that the turbidity of the lower stratum (which

is nearest to the sea bottom) gradually decreases both in maximum and mean

values as the distance from the dredge increases. On the other hand, the

turbidity of Group C shows a maximum value of 27 ppm and a mean value of 2 in

the upper stratum. This shows that the large distance of 200 m lessens the

overall turbidity considerably even though there was sporadic high turbidity

in the area.

96
TABLE 5. TURBIDITY CAUSED BY DREDGING PROJECT NO. I

AT VARIOUS DISTANCES FROM THE DREDGE

Number Turbidity

Group Distance, m Stratum of Samples Max. ppm Mean ppm

A 50 Upper 66 6 2

Middle 66 7 2

Lower 66 61 6

B 100 Upper 127 19 2

Middle 127 18 2

Lower 127 27 3

C 200 Upper 82 27 2

Middle 82 14 2

Lower 82 14 2

Note: "Distance" means distance from the dredge.

Figure 6 shows changes in turbidity versus time in the average of each

observation group. The changes in turbidity are quite similar between Group B

and Group C at various depths in the upper and lower stratum. Although the

range of change was less than 6 ppm and is not very large, it indicates the

variance in dredging operations.

TURBIDITY OBSERVATIONS AT DREDGING PROJECT NO. 2

Dredging Project No. 2 was slated to dredge 730,000 m3 of bottom sediment

in about 10 months, during which three consecutive work days were set aside

for the observation of turbidity around the dredge. Several observations were

carried out in connection with turbidity, but several hours of the last day

were used for investigation of the dispersion of turbidity.

This survey was conducted from 15:13 to 16:10 on May 12. The locations

of the measuring stations are shown in Figure 7. At each of the stations,

turbidity of the three strata as shown in the figure was measured by lowering

the read-out turbidity meter from a sm 1 survey boat circling around each

station. These measurements were taken three times during the day and

three data samples were collected at each station.

For purposes of this study, the measuring stations were divided into

two groups based upon distance from the dredge. Group A includes stations 4,

5, 6, 8, 9, 10, and 11 which were about 50 m distant from the dredge. The

remaining stations, 1, 2, 3, 12, 13, and 14, which were about 100 m from the

dredge, are classified as Group B. Background turbidity of this sea area was

estimated from measured data to be 3 ppm. Table 6 shows the results of observations and calculations. The results were calculated by deducting the background values of 3 ppm from the measured values reported in the Reference 3.

By checking the mean values, it Is noted that lurbidity returns to the

97

I
t6

tE

8 _ ___1 ____ ___ _ ___ - - B-

-1-

Test

rie12 24 1 2 24 12 24 12 24 12 24

_I

IDate JJan. 18 1Jan. 19 1Jan. 20 jJan. 21 Jan.2

Figure 6. Changes in turbidity (Dredging Project No. 1)

B-L means Group B, lower stratum; C-U means

Group C, upper stratum, etc.

200m

5 CK7,SOM l 5OfM[ 5 OM

__ //,• -O

upe 300 00

10 013

0-20 0 9 2

"Figure 7. Locations of measuring stations (Dredging Project No. 2)

98

'I
TABLE 6. TURBIDITY CAUSED BY DREDGING PROJECT NO. 2

AT VARIOUS DISTANCES FROM THE DREDGE

Number Turbidity

Group Distance, m Stratum of Samples Max. ppm Mean ppm

A 50 Uppei 21 2 0

Middle 21 5 2

Lower 21 6 3

B 100 Upper 18 1 0

Middle 18 3 2

Lower 18 4 2

Note: "Distance" means distance from the dredge.

background value near the surface at 50 m or beyond. The turbidity at the

middepths and bottom is only slightly over the background value at the 50-m or

100-m distance. The maximum turbidity was 6 ppm in Group A and 4 ppm in

Group B, both appearing near the sea bottom.

TURBIDITY OBSERVATIONS AT DREDGING PROJECT NO. 3

Dredging Project No. 3 was slated to dredge about 550,000 ms of bottom

sediment in about 4 months, during which two consecutive days were set aside

for the observation of dispersion of turb'Ldity. The observations were conducted during the afternoon hours while the dredge was under operation. At

the start of the survey, three small survey boats began circulating around the

28 stations shown in Figure 8 measuring the turbidity at each I m of depth

down to the bottom. Table 7 shows the observation schedule. As shown in

turbidity

() tidp, current

(S" 7 6 5 4 3 2 1 (St.) 7 6 5 4 3 2 1

50m 50m, 50m1 50m 4 50m1 S 50m 4 50 so4 m50m. 1 S I50n som

D-Line

A-Line -.-

Nov. 26 \trench edge Nov. 27

Figure 8. Locations of measuring stations (Dredging Project No. 3)

99
TABLE 7. OBSERVATION SCHIDULE

Date Order of Test Time

Nov. 26 1 13:40-14:20

2 14:40-15:10

3 15:10-15:40

4 15:30-16:00

Nov. 27 1 13:20-14:00

2 14:00-14:40

3 14:30-15:10

4 14:50-16:10

5 15:40-16:20

Table 7, nine tests were conducted in the 2 days. Although the direction of

the dredging on November 27 was opposite to that on November 28 as shown in

Figure 8, the distance from the dredge to the observation stations can be

regerded as itnchanged throughout the observation period.

The operation period of a dredge consists of the dredging period and the

advancing period; Table 8 shows this arrangement relative to Project No. 3.

One observation time contained one or two dredging periods. As shown in

Figure 8, station 4B was located nearest to the dredge. The observation

results revealed that the turbidity around B-4 near the sea bottom was quite

high. In this area the turbidity meter was scaled out four times out of nine,

showing that the turbidity exceeded 500 ppm.

For purposes of this study, the 27 measuring stations excluding 4B, were

divided into three groups according to the distances from the dredge. Group A

was about 50 m from the dredge, containing stations 3A, 4A, 5A, 3B, 5B, 3C,

4C, and 5C. Group B was about 100 m from the dredge and contained stations 2A, 6A, 2B, 6B, 2C, 6C, 2D, 3D, 4D, 5D, and 6D. Group C was located

about 150 m from the dredge and contained stations 1A, 7A, IB, 7B, IC, 7C, 1D,

and 7D.

The survey demonstrated the turbidity at numerous positions and varying

depths as shown in Table 9. It has become clear that the turbidity of 500 ppm

and more at stations nearest the dredge was lowered to 72 ppm or less at 50 m

from the dredge, and to only slightly over the background value at a distance

of 150 m.

Figure 9 shows chayges in turbidity versus time. In the figure, the

curves of Group B and C (100 m and 150 m) are rather flat, showing that dispersion of turbidity has become steady.

100
- '~ -

- 1i

oo 4 I If

rI r

0 0 !

- - In

- __I 

S- -I

M 

i

ST0

"" .•lI

1-O1

S. . . I . . . •• • a
TABLE 9. TURBIDITY CAUSED BY DREDGING PROJECT NO. 3

AT VARIOUS DISTANCES FROM THE DREDGE

Number Turbidity

Group Distance, m Stratum of Samples Max. ppm Mean ppm

A 50 Upper 72 2 0

Middle 72 9 1

Lower 72 72 6

B 100 Upper 82 5 1

Middle 82 4 0

Lower 82 17 1

C 200 Upper 58 5 1

Middle 58 2 0

Lower 58 12 1

Note: "Distance" means distance from the dredge.

10f

CA GroupA

II C.) I

E6

, I I I

.06

41

0 EGroup A _= aDistance

150m ....

Order of Tes "

Time intervaP 13:40 , 140 min 16:00 0 180 -nin 16:20

Date Nov. 26 Nov. 27 1

Figure 9. Changes in turbidity measurements (Dredging

Project No. 3)

102 ,4

'4

°,
PROPOSED DISPERSION MODEL

When comparing the results of the three dredging projects, some generalities can be seen concerning the distribution of turbidity in various areas of

the sea surrounding the credge. Figure 10 is a comparison of turbidity near

the sea bottom; this figure shows that at a distance of 100 m from the dredge

the turbidity does not exceed more than 3 ppm over the background value in any

observation. The curves in Figure 10 show that turbidity decreases to 2 ppm

at a distance of 200 m. It is difficult to estimate the turbidity beyond

200 m, but the assumption of I ppm turbidity at a distance of I km from the

dredge is not unreasonable.

j4

S2 ProjectNo.2 Prjct No.1

.1 .. S• ProjectN PoetNo.33

050 i00 150 200 250

Distan cefrom drsdge, m

Figure 10. Mean value of turbidity izear the sea

bottom

A proposed dispersicn model could make allowances for the turbidity

mentioned above. According to this model, the mean value of turbidity at a

distance of 100 m from the dredge and near the sea bottom would be 5 ppm over

the background value, and 3 ppm at a distance of 200 m.

For turbidity near the water surface, the results of the three dredging

projects showed that the mean value of turbidity did not exceed the value near

the sea bottom. Therefore, according to the proposed model, the mean value of

turbidity at a distance of 100 m and more froa the dredge and near the water

surface would be less than 3 ppm over the background value.

It -may not be meaningful to compare the maximum values of the measured

turbidity, but it is interesting to find a natural law in such a comparison.

From that point of view, the comparison is shown in Figure 11.

Such maximum values sometimes appear locally and temporarily, and may

indicate the size of deviation from the mean values of turbidity. Otherwise

103

, , I , , i i I I I I I I .
so

40-

.0

E 0

Project No.3 Project No.1

0 Project No.2 I

0 so 100 150 200 250

Distance from dredge, m

Figure 11. Maximum value of turbidity vhich temporarily

appears at the sea bottom

they may appropriately indicate the characteristics of the dispersion phenomenon by the turbulent flow. Either way, they have negligible effects on

living things; therefore, the proposed model contains no maximum value of turbidity, and only refers to its existence without numerical value.

The following conditions should )-e present before the proposed model can

be used:

a. The work should be conducted in a wide axid closed sea area.

b. The sea are& should not have a strong and fixed sea current but

rather a weak current with unsteady directioi.

c. The bottom sediments to be dredged should be soft clay, containing

more than 50 percent of particles less than 0.075 mm in diameter.

d. The dredge should be a 5,000 ps class or smaller.

e. The dredging work to be carried out should be of an ordinary nature.

The mudel may appear too bold of a proposition because it is based upon

observations of only three dt dging projects. However, since the literature (5, 6) concerning past examples of such observations is similar in nature, it can be said that the proposed model does not underestimate turbidity.

CONCLUSIONS

Sin".e tbe dispersion of sediment resuspension caused by dredging depends

on the turbulent flow of seawater, it is quite difficult to make predictions

by applying a mathematical model. Therefore, the practical solution is to

104
show only an empirical model of turbidity distribution. Such a model cannot

be expected to be accurate unless a statistical analysis is made by observing

numerous instances of dredging. However, it is also true that to carry out

observations of turbidity using numerous instances is a problem. This is a

dilemma accompanying prediction of the dispersion of sediment resuspension.

Environmentalists claim that the effects of turbidity of the seawater are

harmful tc the life of fish and seaweeds. Therefore, it is necessary to secure the unders'anding of these environmentalists by fashioning an accurate

model of the dl.spersion of sediment resuspension caused by dredging, in order

to safely carry out dredging work to maintain the sound development of the

economy. For that purpose, tc have as many practical observations of turbidity as possible is a must to overcome all conceivable problems to achieve this

end. The author sincerely hopes that this report will be of some help in

realizing these goals.

ACKNOWLEDGEMENTS

The author wishes to thank Mr. Hiromichi Yamashita, managing director of

Penta-Ocean Construction Co., Ltd., and Mr. Eisuke Sato, chief engineer of Toa

Harbor Works Co., Ltd., for their cooperation and assistance in the course of

compiling this thesis. Thanks also go to the staffs of the three companies

who helped me in carrying out such troublesome work.

REFERENCES

1. Penta-Ocean Construction Co., Ltd., et al. 1983 (May). "Report on

Observation of Turbidity Caused by Cutter Suction Dredge," Unpublished.

2. Engineering Laboratory, Penta-Ocean Construction Co.. Ltd. 1983 (Apr).

"Report on Observation of Turbidity Caused by Cutter Suction Dredge in the

Imari Bay," Unpublirhed, in-house data.

3. Toa Harbor Works Co., Ltd. 1983 (Apr). "Report on Experiment of

Turbidity Caused by a Cutter Suction Dredge off the Hannan Port,"

Unpublished, in-house data.

4. Toyo Construction Co., Ltd. 1983 (Apr). "Report on Observation of

Turbidity Caused by a Cutter Suction Dredge," Unpublished, in-house data.

5. Tokuji Yagi, et al. 1975 (Sep). "Effect of the Operation Conditions of a

Suction Dredge on the Dredging Capacity and Turbidity," Port & Harbor

Research institute Data No. 288.

6. 5th District Port Construction Bureau. 1975 (Oct). "Current Problems of

Harbor Technology," 26th Ministerial Port & Harboz Research Conference

Data.

105
AN ANTI-TURBIDITY OVERILOW SYSTEM (ATOS) USED FOR REDUCING THE

DISPERSION OF FINE SEDIMENTS FROM A DREDGE PLUME

M. J. Cruickshank

Minerals Management Service

U. S. Department of the Interior

12203 Sunrise Valley Drive Mail Stop 646

Reston, Va. 22091

ABSTRACT

In 1976 at the World Predging Conference in San

Francisco, Calif., two Japanese authors, Ichiro Ofuji,

Manager of IHI Special Vessels Design Department, and

Naoshi Ishimatsu, an engineer in the same department,

submitted a prizewinning technical paper entitled,

"Anti-Turbidity Overflow System for Hopper Dredger."

"By the removal of air trapped in the overflow slurry

from a hopper dredge, and the placement of the overflow below the waterline, reductions in visible surface plume effects were achieved by a factor of 40 in

. silty sands. The effects were not so noticeable in

coarse sands. The U. S. Department of the Interior,

"Minerals Management Service (MMS), is responsible for

"managing the production of minerals from the Outer

Continental Shelf. In an effort to further quantify

the effects of installations of an ATOS on a dredge

,. % used for mining offshore, the MMS and the United

States/Japan Cooperative Program in Natural Resources

are preparing a test to take place in Shimonoseki Port

in Northern Kyushu. The purpose of the test is to

characterize the magnitude and behavior of turbidity

plumes associated with a dredging operation with and

without ATOS. Plume characteristics, including magni-

"tudes in three dimensions--trajectory, density, and

density gradients and suspended sediments--will be

measured as a function of time. The test is planned

"for the spring of 1984 from the dredging vessel,

KAIHO-MARU.

INTRODUCTION

Original U. S. interest in the Japanese-developed ATOS dates back to 1976

when Ichiro Ofuji (the inventor of ATOS) presented his award-winning technical

paper on the subject at the 7th World Dreiging Conference (WODCON VII) in San

Francisco. Interest then transcended to the Department of the Interior's

(DOI) Outer Continental Shelf (OCS) Mining Policy Task Force which formally

recommended consideration of ATOS as a "mitigating control system" for installation on hopper dredges used in OCS mining. This recommendation also was

106
.. .. .. .. .--.-..... .. .. ........

strongly supported by the Assistant Secretaries for Energy and Minerals and

"Land and Water Resources.

Now, through the continued interest and support of the United States/

Japan Cooperative Program in Natural Resources (UJNR), we have an opportunity

to examine the ATOS in Japan and learn of its applicability to dredging for

hard minerals, such as sand and gravel, on the OCS. It is felt that ATOS provides the basis for a mitigating control system that will be of great interest

to those concerned with the environmental or fisheries implications of a large

surface plume and the possible accumulation of a blanket of fine sediment

settling out over a broad area of the seafloor.

CURRENT PLANS AND SCHEDULING

Und-r UJNR sponsorship, proposed joint testing of ATOS will involve

interagency participation with the DOI Minerals Management Service (HMS)

serving as the lead agency for DOI. A U. S. Scientific Team cotuposed of four

members--one each from MMS, National Oceanic & Atmospheric Administration

(NOAA), U. S. Geological Survey, and the Corps of Engineers (CE)-and a U. S.

Regulators Team of nine members, made up of representatives from MMS, NOAA,

Environmental Protection Agency, CE, Fish and Wildlife Service, and the Bureau

of Land Management. The U. S. Scientific Team will work with their Japanese

counterparts in designing a test plan to satisfy the desired objectives of the

ATOS experiment.

WHAT IS AIrOS?

"ATOS" is the acronym for the Japanese-developed "Anti-Turbidity Overflow

System" designed to prevent surface turbidity and widespread accumulation of

fine sediments on the seafloor, commonly associated with conventional suction

hopper dredge mining operations. The system, which is U. S. patented, can be

readily installed on hopper dredges currently in service through simple

modifications.

In developing the system, it was learned that during hopper filling and

overflow, air bubbles with entrained sediment in the water cause the surface

turbidity plu~ne associated with hydraulic suction hopper dredging. Using the

conventional overflow process, air is trapped in the mixture of water and fine

*• sediment and then carries the particulate naterial to the surface wher it

"rises in the form of bubbles. In effect, with a conventional overflow system,

the rising air bubbles produce an "air-lift" or "flotation" effect on the

suspended sediment particulates (Figures I and 2).

The ATOS, when adapted to a conventional suction hopper dredge, solves

this problem simply by eliminating entrapped air and discharging the air-free

water-sediment mixture below the waterline. The result is a relatively clear

water column, no surface turbidity plume, and presumably only a small area of

fine-sediment accumulation at the dredge site caused by the system's rapid

suppression of particles (Figure 3).

Japanese tests in fine sand or silt show that ATOS reduces surface turbidity down to 10 ppm, or lower, in suspended solids concentration. This

compares with a test result of over 400 ppm without ATOS.

107
-- ~0 -

Figure 1. Conventional 1Lgure 2. Conventional

overflow system overflow zystem

•''Overfl'ow weir Hopper

Inclined Hydraulic baffle plate cylinOi

-trough

I L

Figure 3. Anti-Turbidity Overflow System

of the TOKUSHUN-MARU NO. 1

Other Japanese tegiq at a silty sand deposit show that ATOS can reduce

the l.evel of turbidity down to about 5 or 10 ppm. In these tests, the

Japanese determined turbidity levels versus time and water depth.

Visual observation of changes in the surface turbidity plume. with and

"without ATOS, can be easily -oted. The KAIHO MARU used in the test program is

one of the large ATOS-equipped hopper dredges operating in Japanese waters,

mainly by the Ministry of Transportation (Table 1).

T"he Japanese have also conducted extensive model tests of turbidity diffusion using a 1:20-scale actual model of the trailing hopper dredge, SEIRYU

MAR(J, owned by the Ministry of Transportation. The model was towed at a con-

-: stant speed while turbidity diffusion due to overflowing muddy water was

recorded photographically by three 35-m cameras, three underwater cameras,

and a television camera. These model investigations contributed significantly

to the ultimate design of ATOS, including the feature of discharging the hopper effluent through discharge pipes protruding 2 a below the ship's hull (1).

108
TABLE 1. MANUFACTURING RECORD OF ANTI-TURBIDITY

OVERFLOW SYSTEM (ATOS) FOR HOPPER DREDGES

Hopper

Dredge Capacity, m3 Owner Delivery Remarks

TOKUSHUN-MARU NO. 1 4,000 Tokushu 1971

Shunsetsu

Co., Ltd.

KAIRYU-MARU 1,700 Japanese 1974

Ministry of

Transpor-

"tation

KAIHO-MARU 2,000 Japanese 1975

Ministry of

Transportation

HAKUSAN-MARU 1,300 Japanese 1978 With automatic

Ministry of control system

Transportation

* SUMBAWA 1,000 Indonesian 1978

Government

* SEIRYU 1,700 Japanese 1978

Ministry of

7• Transportation

"* JAPANESE VERSUS U. S. INTERESTS

Japan's offshore sand and gravel mining industry is the world's largest

with offshore produc.ion of about 70 million tons per year or about 20 percent

of Japan's total production of natural aggregate. Likewise, the Zapaaese do a

*. considerable amount of dredging with large trailing suction hopper dredges in

* connection with creating harbors, navigation channels, and offshore islands.

Some of these operations are in close proximity to fishing grounds or marine

cultivation farms (for seaweed, pearls, or fish). Recognizing that turbidity

from conventional hopper dredging operations could damage these resources,

such operations are sometimes put under restriction or suspension. Now, with

.* the installation of ATOS on these dredges, dredging can safely proceed in

-* these areas without any restrictions.

Extensive testing and actual field application of ATOS by the Japanese

have proved successful in solving these specific problems of the nearshore

109
i

environment. However, vith concern over the surface plume's migration toward

seaweed beds and cultivation farms, the Japanese concentrated their earlier

studies on the plume at the sea surface, namely on surface turbidity diffu-

".. sion. Now, with joint U.S./Japanese interest extending to sand-mining operations in the open-shelf environment, there is a need for determining what takes

.- place at or near the seafloor, with and without ATOS, in terms of suspended

"sediment dispersion characteristics and the areal extent of the "blanket of

fines" accumulating on the seafloor (2).

"At a meeting of the Joint Scientific Committee, ATOS project, held in

Tskuba, Japan, on 27 May 1983, it was resolved to carry out tests in May 1984

using the dredge KAIHO MARU operating in Kanman Channel at the Port of

Shimonoseki in Northern Kyushu (Figures 4 and 'i), Turbidity from the action

"of the draghead on the seabed will be examined in the experiment as well as

turbidity from the hopper overflow discharge, with and without ATOS. Measurements of plume magnitudes in three dimensions, plume trajectory, plume density,

and density gradients and suspended sediments, will be taken at selected

points during the dredge operating cycle to characterize the magnitude and

behavior of the plumes (Table 2). Background measurements at selected points

will be taken before and after the 2sts.

It is hoped that sufficient data will be gathered to allow assessment of

the value of installing ATOS equipment on dredges used for mining offshore to

mitigate the formation of environmentally undesirable sediment plumes.

REFERENCES

1. Yagi, T., et al. 1977. "The Investigation on Turbidity Due to the Drag

Suction Dredger," Technical Note No. 279, Port and Harbour Research

Institute, Ministry of Transport, Japan.

2. Hess, H. D. 1983. "United States/Japan Joint Testing of ATOS, An

Experimental Control System for OCS Mining by Suction Hopper Dredge,"

Unpublished presentation to UJNR Marine Mining Panel and ATOS Study Team, 5 Minerals Management Service.

110
II

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

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S S4

FigureI~BS Loaio 4.tae f TS et
: : 'i

- iji

,%b

- I

...

,.. I1

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%;h

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TAMLE 2. MEASUREMENT PARAMETERS AND EQUIPMENT

"Action/Objective Measurement Parameters Equipment

To characterize the magnitude At least two repetitions per Three boats for

and behavior of turbidity discharge cycle of dredge plume transverses

plumes associated with a and one after shutdown.

dredging operation with and Suspended sediwithout ATOS. Using a In plume, at each sample ment sampler

Lagrangian approach, site through water column bottles, Van

turbidity plume repetition: Dorn type (4

characteristics including: a. Suspended sediment each boat)

a. Magnitude (three- (mg/1).

dimensional). b. Time and time incre- Transmissometers

b. Trajectory. ment (sec) at and (3)

c. Density and density between sampling. Portable current

gradients. c. Salinity and tempera- meter (1)

d. Suspended sediments ture (Gpt and "C).

measured as a d. Current velocity and Salinity and temfunction of time. direction (cm/sec). perature measuring devices

At selected points, as (possibly inappropriate with time and corporated with

conditions: Van Dorn sama. Swell and sea state plers) (1)

(period, height,

direction). Stop watches (4)

b. Wind velocity (cm/sec),

direction. Navigation equipc. Tide stage. ment (minid. Depth (m). ranger type)

Outside plume, control Hand-held

"points, once per discharge anemometer (1)

cycle, at points to be

selected: Communication

a. Ambient suspended (two-way

sediment (mg/L). radios) (5)

b. Salinity and

temperature. Grab samplers

(ppt and °C). (Shipek type)

c. Current velocity and (3)

"direction profiles.

d. Swell and sea state Inductive

(periods, height, salinoLeer (I)

direction). V Light plane or

At dredge, point of tethered

discharge: balloon with

"a. Bottom surface TV (1)

sediments.

b. Discharge material Camera (1)

characteristics.

*1.

'I
NEW TECHNIQUES DEVELOPED IN JAPAN FOR OIL SPILL CLEANUP

I. Ofuji and N. Ishimatsu

Japan Workvessel Association

2-9-7 Yaesu, Chuo-Ku, Tokyo, Japan 104

ABSTRACT

In the last decade, the total number of

reported water pollution incidents in Japan has

decreased by 36 percent. Of these incidents, 80 percent are oil spills. Three oil recovery systems currently being used in Japan are discussed in this

paper. The first one is an oil recovery system that

uses aeration to separate the oil and the water. It

is intended for recovery of low viscosity oil that

spreads itsslf over the water surface as a thin

film. The second, or rotary bucket oil recovery

system, Is used to clean up spills of high viscosity

oil, like crude or heavy oil, which remains on the

water surface in a thick layer. The third is a

gelatinization recovery system that converts all

types of oil into a semisolid consistency for easy

mechanical recovery.

INTRODUCTION

Oil spills at sea are a worldwide concern. This concern is expressed by

specific oil-spill-related environmental protection regulations established by

international conventions and domestic laws in many countries.

Since the establishment and enforcement of oil spill regulations in

Japan, the number of oil spills reported has steadily decreased. Yet, a

considerable number of oil spills due to shipwreckage, collusion, or improper

operation of ship's equipment will inevitably continue to occur in spite of

these regulations and human efforts.

Oil from spills may float on the sea surface or exist suspended in the

water below the surface. Wave action is capable of forming certain types of

oil into "oil balls." Floating, suspended, and "oil balls" may drift ashore

to contaminate beaches or sink to the sea bottom and damage the ecological

environment.

This paper introduces new Japanese technology for recovering oil spills

at sea.

114
CURRENT SEA POLLUTION IN JAPAN

Reported Incidents of Sea Pollution

Figure 1 shows the total number of sea pollution incidents reported in

Japan between 1971 and 1980. As indicated in this figure, the total number of

incidents has decreased yearly from its peak of 2460 cases in 1973, except for

a slight increase in 1979. Despite a 36 percent reduction in the number of

incidents, 1581 cases were still reported in 1980 and there is no guarantee

that the number of incidents will continue to decrease in the future.

2.500 2.460•~2,366

22.203 2.00 / 2.060 1.985 2,0o28 / 1.983 1,•868 Z / \ -. 7.50 1.733

S1.500. 1,621 1,0 1.581 Tocal

r. 1,437

1^^ 10T1,300T 1,339• 1,257 1.228

1Oil S1.000" 1.099

0

0

z 500- 291

172 205 246 206 •- -- 259. 248 183 . 192 Red Tide

147 155 161 Others 0 T - I I I I I 1-

1971 '72 '73 '74 '75 '76 '77 '78 '79 '80

Figure 1. Reported number of sea pollution

incidents in Japan, 1971-80 (1)

Among all cases of sea pollution, oil spills comprise the majority of

incidents with 1228 cases in 1980 (78 percent of total incidents), followed by

red tide with 192 incidents (12 percent of total), and all other 161 incidents,

such as garbage disposal or industrial wastewater, accounting for 10 percent

of total incidents.

Oil Balls

Around 1965, deterioration of the natural environment of beaches and sea

coasts became a social concern as tarlike, adhesive solidified blocks of oil

(*'oil balls") drifted on the sea surface and reached some beaches on the

southern islands of Japan. With the expansion of Japanese economy since 1965,

115
the number of such incidents has increased, causing damage to fishing grounds,

seaweed farms, pearl cultivation farms, and recreational areas.

It is believed that an oil ball is generated through the effects of wave

action on an oil-water mixture. The source of the oil could be dirty ballast

water, tank cleaning water, sludge waste disposal at sea, or any number of

other sources of oil in the marine environment.

The characteristics of an oil ball are listed in Table 1.

TABLE 1. CHARACTERISTICS OF OIL BALLS COLLECTED FROM BEACHES

Characteristic Range Mean

Specific gravity, 15/40C* 0.79 - 0.925 0.856

Viscosity, 210OF cst** 13.05 - 28.61 18.88

Drifting point, *C 35.5 - 62.5 52.5

Coal, % 2.57 - 14.02 6.7

Mineral, 2 0.00 - 7.41 1.36

Sulphur, % 0.089- 2.318 1.18

pH of oil 2.1 - 6.75 3.8

Total acid equivalent, KOH mg/g 2.36 -100.98 24.3

Foreign material, % 5.74 - 15.95 10.48

• Oil density (15*C)/vater density (4"C).

** Centistokes at 210*F, nearly equal to cP (centipoise).

The majority of oAl balls drifting on the sea surface are 5 to 6 mm in

diameter, but can be as large as 40 =. In comparison, the sizes of oil balls

that reach beaches are generally larger, i.e., 10 to 50 mm in diameter in most

cases, and, sometimes, even bigger balls, up to 500 mm in diameter, are

observed (2).

The specific gravity of oil balls that reach the beaches is usually lower

than 1.0. However, some oil balls containing gravel or sand with a specific

gravity greater than 1.0 have also reached the beaches.

When driAting on the sea, oil balls extend over a wide area and form wide

belts with varying lengths. Wind driven and tidal currents can transport the

balled oil to coastlines far removed from the actue'. spill and deposit the oil

along sandy and rocky shores.

Damage Caused by Heavy Crude Oil Spills

A recent report states that crude oil spills in the Persian Gulf spread

at a rate of 100 to 300 m/hr. While the crude oil drifts on the sea surface,

116
the light, less adhesive and volatile oil separates from the heavier oils,

spreads in a thin film, and, due to solar heat, vaporizes. After vaporization

of the light oil, the crude oil becomes more dense and begins to sink and

drift Just below the sea surface.

The crude oil spilled in the Persian Gulf has a higher specific gravity

(0.92) than other oils, such as Iranian light (S.G. 0.85). Due to its higher

density (in relation to the specific gravity of seawater), the oil sinks and

remains in the water at a depth greater than 50 cm below the surface. As oil

spills continue to occur, it will become more probable that the more dense

portions of crude oil drifting in the water will reach the nearby seacoasts or

settle onto the sea bottoms resulting in widespread toxic deposits.

RECOVERY OF SPILLED OIL

Although it is almost impossible, at present, to vacuum all the largescale oil spills, some technology for oil spill recovery is available and is

practical for use in harbors or confined areas. This discussion deals with

some of the technology developed in Japan.

Recovery System for Low Viscosity Oil

Among various recovery systeus for low viscosity oil, the system that

uses aeration to separate the oil from the water is a unique one. This system

was developed by IHI for SOKAI and NO. 2 SOKAI, two self-propelled oil recovery

ships with catamaran hulls. Both ships are owned and operated by the Second

Port and Harbor Construction Bureau, Ministry of Transport. (Sokai literally

means ",lue Sea" and "Cleaning Sea.") Both ships are now engaged in routine

recovery operation of thin films of oil which float on the sea surface. Figures 2 and 3 show a photograph of SOKAI and the general arrangement plan of

NO. 2 SOKAI, respectively.

Figure 2. Oil recovery ship SOKAI

System Operation

By a combination of the floating regulating weir which allows the surface

oily water to flow into the separating tank, aeration by small air bubbles in

the separating tank, and vacuum suction, the system separates oil from the

117
11 II

* * Boiler & H*%hA&lic Power Lkt±C

.. . . ... .. . .. . . . .. . . . Ro (S abs

Figure 3. General arrangement plan of NO. 2 SOKAI

118
r

water and recovers the oil. A recovery schewatic is shown by Figure 4. The

actual operation of this recovery is as follows:

a. The oil recovery device ("skimmer barge") is moved into operating

position.

b. The air compressor begins to pump air through pipes arranged

throughout the first separating tank.

c. While the ship moves forward 't low speed, the seawater discharge

pump begins to discharge the water in the lower parts of the first

and second separating tanks. When the water levels in the two tanks

become low enough, the surface oily water in front of tOe ship flows

into the first separating tank.

d. The oily water is aerated in the first tank where the oil adheres to

the small air bubbles and floats to the surface underneath the oil

separating plate. From the plate the oil flows into the second separating tank over the second flow regulating weir.

e. The vacuum pump suctions the separated oil through the floating

oil-water suction equipment connected to the vacuum suction tank.

f. The suctioned oil is temporarily stored in the vacuum suction tank

until it is eventually transferred to the large capacity oil storage

tenk. If the percentage of vater is tjo high in the oil-water mixture

in the vacuum tank, the oil-water separating equipment may be used to

reduce the water percentage before transferring the oil for storage.

Figure 5 shows the general arrangement of the skimmer barge.

Operation of SOKAI and NO. 2 SOKAI for Oil Spill Recovery

Tokyo Bay, where SOKAI and NO. 2 SOKAI operate, is surrounded by highly

populated cities, including three cities with a million people- Tokyo,

Yokohama, and Kawasaki. The total population of the bay area exceeds 20 million. The Tokyo Bay area also forms a large industrial complex composed of

steel mills, chemical refineries, shipbuildiuLg, electronic industries, etc.

Since a huge amount of cargo to and from this area is transported by ships,

Tokyo Bay is vital to the economy of the area. The total number of ships going

into or out of the Bay is frequently as high as 750 per day. In addition,

ferries, barges. work vessels, and fishing boats operate within the Bay.

Naturally, traffic in the navigation channels is heavily congested and a high

probability of accidents exists. Scattered in the bay area are thirteen oil

refineries and five sea berths. Ouc of 750 ships navigating through the channel at the entrance of the bay on a given day, 150 are oil tankers. Under

such heavily congested conditions, collisions between ships or grounding of

ships is not uncommon and a considerable number of oil spills are reported

every year. Both SOKAI and NO. 2 SOKAI have been dispatched to clean up such

oil spills since their commissioning.

119

' ' ' ' ! ' l l l l l l l l l l l l l'
-41

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to c

1.CL

0 0

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06

120
m~~- ' .7-7 7 .. a

AFT Fo

C. . - -- -- --- , C.--- L•t 

X

"Fig uG ar g t f

,OKAI o NO.• 2 SAa ipthdupnrqeto h artm aeyOfc

C Iro..W.T

S~of Tokyo Bay (3). Figures 6-8 are photos taken during those operations.

Features aUnque 

:':Th.• two unique features of the aeration system are:

i:]a. The cystem is suitable for recovery of relatively low viscosity oil

w- hich is found almost daily on the sea surface as "rainbow" film. iThe rneof vsoiyfor effective reoeyis from I to a~proxiSrange viscoity rToaer

mately 3,000 cat.

b. As the oil is separated from the water by the action of numerous tiny

f T air bubbles and auctioned by v.icuum pressure into the oil separating " tank, no additional materials, such as oil at or chemical agents,

are required. The system itsutlf can recover low-viscosity oil which

wcannot be caught by an oil mat.

Recovery System for High Viscosity Oil

"-A reovery system for high viscosity oils, s.ch as emulsified oil or Solidif Aed otl balls, was developed by the Second Port and Harbor Construction

: Bureau, Ministry of Transport, Japan, and Iuh and fitted on SOKAI and NO. 2 SOKAI. This r system is called the rotary buclwt oil recovery system.

Bra Miisr . of Tranpor, Jaa, an I H an f ne on l KI an NO 2

121
TABLE 2. SOME OIL SPILL INCIDENTS FOR WiHICH SOKA MID/OR NO. 2 SOKAI WERE DISPATCHED

Amount

and Type of Oil Recovery Operation

Oil Spilled Oil &

Source of Oil (Qty. or Size Cause of Recovery Days Water

Date Spill of Oil Belt Spill Ship Engaged Recovered Remarks

% 3 11-08-75 Unknown 4 ka x 20-30 a Unknown SOKAI 1 22 a

C heavy

3

04-01-76 Lumber carrier Not available Unknown SOAI 2 115 m

11-3G-76 Cargo ship 20 ki Collision SOKAI 0 0 Prepared

(5.200 gSl) for operstion.

but cancelled

02-04-79 Land storage tank 50 kl. C heavy Bottom SOKAI 1 0 Prepared

(13.000 gal) breakdown for operation.

but cancelled

3 03-08-79 Oil supply ship 500 1. C heavy PFioperation SOKAI 1 38 a Oil 1-1.52

(130 gal)

04-03-79 Car ferry 2 km x 50-100 a Unknown SOAI & 1 0

C heavy No. 2 SOKAl

04-05-79 Land storage tank 200 kl, crude Crack in SO1I & 1 43 a3

(52,000 gal) tank plate No. 2 SOAI

3 "04-25-79 Container ship IOOC a x 70 a Misoperation SOKAI & 80 a Oil 1-1.5Z

"No. 2 SOlAI

09-13-79 Oil tanker 4 kl. A heavy Collision SOUAI 2 100 a Oil 0.1-

Chemical tanker (1,040 gal) 0.5%

01-19-80 Tug boat 500 1, A. Colliso" No. 2 SOKAI 0.5 0

"Oil tanker (130 gal)

B heavy

01-19-80 Oil aupply ship 165 1. C heavy Misoperation No. 2 SOKAI 0.5 33 a3 Oil 0.5%

(43 gal)

3

02-06-80 Cargo ship fl/A Misoperation No. 2 SOLAi 2 10 •3 Oil 0.5%

12-07-81 Sand barge 1600 a x 500 a Capsize SOKAI & 1 60 a3 Oil 0.5!

No. 2 SOKAI

03-22-82 Coal carrier 600 kl Grounding SOrAI & 0 0 Standby

(156,000 gal) No. 2 SOKAI

.122
-L

Figure 6. Oil spilled on the sea Figure 7. Aeration in the first

surface separating tank during

operation

"Figure 8. Oil separated by aeration

In 1974, the breakdown of a large storage tank in an oil refinery

released a huge amount of heavy oil onto Seto Inland Sea of Japan. The

"released oil remained on the sea for months, became emulsified, and created

"conditions which made recovery of the high viscosity oil very difficult. All

"sorts of then-known methods of recovery were mobilized, but, unexpectedly, one

of the most effective methods was the use of very primitive fishing

tools--pails and wire net (see Figure 9).

123
Figure 9. Fisherman recovering

""N spilled crude oil usi.ng

hand nets and pails

Using this concept, a mechanical system which replaces the manual labor

of fishermen was developed and named rotary bucket oil recovery system. The

principles of the system are described below.

As shown in Figure 10, buckets with bottoms of wire net are fixed arou.d

an axle which is rotated by a hydraulically driven motor and belt. By the

rotary action of the bucket axle. the oil on the water surface is moved forward

and concentrated in front of the baffle plate where it is skimmed up by the

bucket which releases the accompanying water through the wire net. Skimmed

oil is automatically ecraped off into the receiving trough and transferred by

"the screw conveyor to the oil suction mouths at both ends of the conveyor and

pumped into storage tanks through fixed pipings. This operation is repeated

continuously with the rotation of the bucket axle. The wire net is inter-

"changeable and the appropriate mesh size is selected for each oil spill recovery

mission. The whole unit is replaceable so that other types of recovery units

can be used. Replacement of the unit is accomplished almost as easily as

changing a cassette in a video recorder.

System Performance

"Table 3 shows the results of a recovery test conducted in a test basin

with smooth water. Test conditions are listed below:

a. Thickness. Thickness of the oil layer on the water surface was

"approximately 70 ur for B heavy oil and approximately 100 mm for C

heavy oil.

b. Time. The time of the test was January, when temperature was very

low. Oil was emulsified to ensure high viscosity. Emulsification

was accomplished by means of pumps which circulated the oil sufficiently to accomplish this purpose.

124
.11

40

Ph

41

coU

12
TABLE 3. PERFORMANCE OF ROTARY BUCKET OIL RECOVERY SYSTEM

Oil Mesh

Wheel & Water Size of I Oil Viscosity* Revolutions Water Oil Concentration Wire

Used cP rpm m3 /hr m3 /hr % NeL

B heavy 6,000 10.0 30 21.0 30 7

B heavy 50,000 5.0 30 26.7 11 7

B heavy 50,000 15.0 25 13.2 56 2

C heavy 150,000 3.5 30 28.2 6 2

C heavy 450,000 5.5 30 25.5 15 2

•'•C heavy 1,000,000 6.5 30 22.5 25 2

C heavy 1,400,000 7.0 30 21.0 30 2

C heavy 700,000 6.0 30 18.0 40 4

C heavy 1,000,000 5.5 30 15.0 50 7

* cP: Centipoise: 1/100 of poise, nearly equal to cst (centistokes).

c. Water concentration. Data in Table 3 were measured by weight ratio

of water separated by gravity settling versus total weight of oil

and water recovered, exclusive of water caught by emulsified oil,

i.e., the apparent water concentration.

Test results are listed below:

a. It was proved that the system was widely adaptable to different

viscosities of oil from some thousands of cP's up to one million cP

and higher by selecting appropriate mesh of wire net and different

oil viscosity conditions.

b. There is an optimum mesh size of wire net for each oil viscosity

condition.

c. Oil with a viscosity greater than 500,000 cP could be transferred

with no problem due to the lubricating action of a water film on the

inside of pipes. Figure 11 shows viscous oil greater than 500,000 cP

being discharged from a transfer hose.

Unique Features

The system is capable of recovering oil with a range of viscosity from

5,000 cP to 1,500,000 cP, which cannot be recovered by other methods such as

"direct suction by pumping, adhesion recovery system, or oil absorption mat.

Compared with the gelatinization method which uses chemical agents

* (discussed below), the operating cost of the bucket system is much lower.

126
Figure 11. High viscosity oil being

discharged

Gelatinization Oil Recovery System

Another method of recovery for relatively small oil spills in harbors is

gelatinization by a chemical agent which solidifies on contact with water and

forms a "mousse" together with the oil. The mousse can be recovered easily by

wire net or other similar devices. This system has been studied by the Japan

Association for Preventing Marine Accidents and has been applied to a seasurface cleaning ship built in Japan (Figures 12 and 13). Chemical characteristics of the gelatinization agent are listed in Table 4 (4).

I

Ii

Figure 12. Sea-surface cleaning ship with

gelatinization oil recovery

system

Application

d Between the two hulls of a sea-surface cleaning catamaran, a rotor with

"disks is positioned above the water surface so that the lower part of each

disk is immerseý. Near the bow, ahead of the rotor, nozzles for spreading

*, gelatinization agent are positioned over the water surface by pumping. When

"the ship is moving at 1.0 to 1.5 knots, the oil on the sea surface flows into

127
- -, ---- *-- -- - - -

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

gelatiizatio oil rcoverysyste

128Sradr
TABLE 4. PHYSICAL PROPERTIES OF GELATINIZATInN AGENT

Item Description

Appearance Pale yellow liquid

Main ingredients Amino acid derivative; content: 9Z

Specific gravity 0.8 (300C), 0.87 (10"C)

Viscosity 16 cst (30*C), 27 cst (10°C)

Flash point 82*C (open)

Freezing point Below 06C

the well between the two hulls. Near the bow the gelatinization agent is

spread over the in-flowing oil and water. When the mixture passes through the

rotor with disks, the oil, water, and chemical agent are stirred to form gela- tinized mousse which is caught in the recovery container by a textile net.

The solidified oil in the mousse is recovered for delivery to the land processing facility by lifting up the container. The container amount of gelatinization agent for this purpose is about 30 pel-cent of agent per unit of spilled

oil by weight.

Recovery Examples

To date, many incidents of oil recovery by gelatinization have been

reported. The following are two noteworthy examples:

a. In October 1979, a Chinese 8000 DWT cargo ship grounded off Erimo

Cape, Hokkaido, northern island of Japan. This resulted in a spill

of 14 tons of A and C heavy oil in the flooding engine room. A

gelatinization agent was spread over the surface of the oil spill by

portable pumps. The entire amount of spilled oil was recovered in

the form of gelatinized mousse in hand nets in 10 days.

b. The grounding of a 3000 DWT lumber carrier off Rumoi, Hokkaido, in

January 1980 caused an oil spill (C heavy oil) on the sea surface.

While the spilled oil was held within an oil fence, a gelatinization

agent was spread from a small boat and the 6.4 tons of spilled oil

was recovered in 9 days.

Outstanding Features

After oils, including crude and heavy oils, spill on the sea, their

nature changes as time lapses. Certain oils remain liquid, but others become

solidified into a semisolid "mousse." To date, no single mechanical system

can recover all such states of oil.

The gelatinization agent solidifies all types of oil into a form which

can be easily recovered like other floating debris by a mechanical method. In

other words, the most unique feature of the gelatinization method is that it

can recover all sorts of oil, which no other single oil spill recovery method

can accomplish.

129
Figures 14 and 15 show gelatinized C heavy oil on the water surface and

recovered mousse, respectively. Gelatinized diesel oil recovered by a hand

net is shown in Figure 16.

Aa.'

Figure 14. Gelatinized C heavy oil Figure 15. Recovered mousse

Dt-- .11

Figure 16. Recovery of mousse by

a hand net

The effect of the gelatinization agent on marine life was examined by the

Water Pollution Prevention Committee of the Japan Marine Accidents Prevention

Association and the results showed little adverse effects on fish, shellfish,

plankton, seaweed, etc. The use of a gelatinization agent causes no harm to

such marine life.

According to the safety code stipulated by the Ministry of Transport, the

concentration of other oil processing chemicals allowed in the water in terms

of toxicity against fish is 3,000 ppm while the concentration of gelatinization

agent giving the equivalent toxicity is 42,000 ppm. This indicates that the

agent is safe for marine life.

The solidified mousse does not emit any flammable gas. This eliminates

danger of fire which greatly eases recovery and processing work afterwards.

The gelatinized mousse is lightar than, and free of, water and is not

adhesive, which ensures e-sy recovery by manual methods or mechanical devices.

In addition, the gelatinized mousse remains solid below the temperature of

130
60*C and recovery efficiency does not decrease, even in suiier. Storage and

transportation of mousse are easily accomplished.

CONCLUSIONS

Three typical oil recovery systems currently used in Japan include:

a. A recovery system for low viscosity oil which spreads itself over the

water surface as a thin film layer.

b. A recovery system for high viscosity oil, like crude or heavy oil,

which remains on the water surtace in a thick layer.

c. A gelatinization recovery system which solidifies all types of oil

into a mousselike material for easy mechanical recovery.

In spite of the many oil spills which occur on a worldwide or even a

regional basis, there are not usually enough spills in a given local area to

make it cost-effective to maintain single purpose oil spill recovery ships.

It would be more economical to have ships, such as tugboats or dredges, which

can perform other missions besides oil spill recovery. As a matter of fact,

some such ships have already been built.

The ships with the gelatinization oil recovery system introduced in this

paper are normally used for recovery of floating refuse in harbors, and can be

dispatched as oil recovery ships upon the occurrence of oil spills.

The authors will be pleased if such oil recovery systems should

contribute to maintaining the world's irreplaceable and beautiful sea

environment.

REFERENCES

1. Maritime Safety Agency, Japan. 1981 (Aug). "Current State of Maritime

Safety."

2. The Japan Workvessel Association. 1977 (Mar). "A Report on the Study of

Oil Balls Recovery Ship."

3. The Second Port and Harbor Construction Bureau, Ministry of Transport.

1982. "Oil Spillage Incidents for Which Oil Recovery Ships Were

Dispatched Upon the Request of Maritime Safety Office."

4. The Japan Association for Preventing Marine Accidents. 1980 (Sep). "Oil

Recovery by Celatinization."

5. IHI 1983. "Sea Surface Cleaning Ship With Oil Recovery System

DISFLOATER."

6. Aginomoto Co. 1980 (Jan). "Oil Spill Gelatinization Agent."

131

/ -
THEORETICAL CONSIDERATION OF POND AND

SPILLWATER TREATMENT DESIGN

Y. Yoshida, Chairman of Technical Committee

M. Natori, Executive Director

Japan Bottom Sediments Management Association

15 Sankyo Bldg. 7-12, Tsukiji 2-chome,

Chuo-ku, Tokyo 104, Japan

ABSTRACT

In the treatment of dredged material, we must

determine the necessary factors for pond design or

spillwater treatment design. To do this, laboratory

tests must be performed. If the test results are evaluated correctly, there is no problem. However, it is

not always easy to evaluate them theoretically.

For example, the mean settling velocity of solid

particles is usually obtained as the angle of the tangent line to the descending curve of the clarified

liquid boundary. Strictly speaking, this is not

correct. This paper deals with such problems.

SEDIMENTATION TEST

The treatment of dredged material is based on the separation of solids

and liquids. The separation of a solid from a liquid is usually achieved via

a settling pond. The size of a settling pond depends principally upon the

mean settling velocity of the sediment particles concerned.

To learn this, a sedimentation 200w

test is performed using an acrylic 1

pipe which usually has a diameter of

200 mm and a length of 1500 to 2000 mm

(Figure 1).

In chis test, the boundary between

cl.arified (liquid) and suspended solids 7

(SS) containing liquids, which descends Flang

with time, is measured by heights e

according to time. Figure 2 shows an

example of the test results. 0

Flange

Figure 1. Sedimentation

test apparatus

132

...................................--.
Time, see

0 20 40 6 0 So100 120 14 160 180 200 220 AO0

2000

1800

1600 i

-10

1400 0

1200

No.1I

1000 %

' No.2 20

800

600 

CM

Figure 2. Precipitation curve

In Figure 2, two precipitation curves which have initial concentrations

of 19,420 mg/£ (No. 1) and 14,860 mg/L (No. 2) are plotted. The movement of

solid particles in a test pipe is represented as follows:

0 V

aac

K'(C" - + a-(

z

z2

ac - w + K- (1)

at az az 2

133
where

Z = Water depth

t = Time

c - Concentration of SS

w - Mean settling velocity of floc

K - Diffusion coefficient of floc in the vertical direction

As the solution of Equation I we have the following equation, using a boundary

•" H

., condition t = 0 , z = , and C = C

Sw H\ 3 bw

C C -n t 2K -2 2K b 2K

C bw H 3 bwn (2)

i"cs2K 0cos j- 2 - b in 2K 2

• 4Knwb'----1

where

C SS concentration

C - Initial SS concentration of dredged material

"H - Initial liquid height

Here putting,

bw 3 bw

2- 2 b sin 2K z ":a (Z) -(3) zbw H 3 bw H

cos K sin 2K 2

We rewrite Equation 2 in the following form:

2 2Kz H

"C -n t 2 Q (Z) (4)

* 0

* Since the variation of SS concentrations against t and z is now known, we

S"can calculate the concentration of clarified liquid:

"134
•.fd -F

H-h

S..c..:.

t 0O after t

H-h 2

Cne2 t 2K K2 e W 27 [ C.b o(H-h) Hh sin L!Hh~~

0 w 2 K b 2K (

- Hh(+ 2 ) (cs ---H-3sin-b

Here we set two nondimensional symbols as follows:

a f" bw b, H

(6)

w H

e

(I b2)(c bw H 3 sin li\ 0 8 I T sin 2K 2/

Y- f,- b, H -h)

(7)

r2,

w (H-h) b

2K-3 bK

113

• , 0aare :

![135 /thw x
.4

"Hence we have

"" ce-n t 2K~w (8) 1 w H -h

*l or

C 2

F(H - h) H - h o 2K e-n t (9) - v

This is an equation for the descending clarified liquid surface.

As Equation 9 shows, the descending height of liquid surface is repre- SH-h

sented by a function of -H- , which is not a single function such as an

exponential one. y

One should note that Equation 9 is not complete for the whole settling

procedure because in the latter half zone settling and consolidation of solids

occur. Therefore, some difference between the curve of Equation 8 (Figure 3)

and an observed curve is inevitable.

t

4.

"Free settling

H-h

Zone settling

Consolidation

Curve of Equation 8

Figure 3. Curve of Equation 8

SETTLING VELOCITY

The main purpose of a settling test is to obtain the mean settling velocity (Figure 4).

13

., 136 N%.

N'
t

% I _

h

Figure 4. Determination of settling velocity

The mean settling velocity is usually obtained from a tangential line at

some early time f or brevity of calculation. But this is not correct. The

descending rate of clarified liquid surface is represented as follows from

Equation 9:

F(H -h) o 2K 2 nf2t (0 - 1 - ) _( 0

As the equation shows, the angle of a tangent line is a complicated func2 - ~ tion of n , b , w , and K . It does not represent the settling velocity.

The factor which strongly affects the slope is the value of n 2. The reason

lies in the 'act that the descent of the clarified liquid boundary is caused

* not only by the settling of solid, but also by the diffusion of solids particles. If we want to know the true settling velocity, we must compute Equations 4 and 8 with measured data.

S.

SWELLING OF DREDGED MATERIAL

* Sediment at ýhe water bottom has a void ratio (e ) in its natural state.

0

When it is dredged, the sediment particles are disturbed by the dredge cutter

and become loose. Therefore, the dredged material has a larger void ratio

5%

tha thto Fheimuent. Conequernatlywhn o wet n velacityit etln

podshe meansettaccoun feorityhis uswelln ofbtheineded frmatanenrial.nea

137
iFe

* 1 SSSS

Sediment Dredged

Material

The swelling of the dredged material is represented as follows:

.', l + e

0

"From a settling test, we can obtain the void ratio of dredged material by the

following equation:

.i•" Ys h

.• h. . . ... C HI (12)

0

5 where

C Initial SS concentration of dredged material "0

"'"s" Specific weight of dredged material

Sh -Settled thickness of solid

H - Initial liquid height

As to the value of e , we must measure it beforehand.

L0

138
When designing a settling pond, the capacity should be determined by the following equation:

V - V E ( I-1H (13)

where

V - Pond capacity

V - Sediment quantity to be dredged 0

c - Swelling ratio

AH a Settlement of dredged material

REMOVAL COEFFICIENT OF SS

In a settling pond dredged material is separated into solid and liquid

components. The former settles in the pond and the latter flows over a

spillway.

In most cases, the quality of the spill water is not very clean from such

sedimentation. Therefore, spill water treatment is necessary. In this case,

it is most important to predict the spill water quality because it is basic to

treatment design.

ac a c C c _•ca -. •=..c +---* -- 4 x-• - - -

i- CA

=0

" *7' • '', -... --... -- -P "-- R: Removal

"-: - 'coefficient

z

"The movement of solid particles in a pond is represented by the following

equation:

ac ac 2c _2

+ t +u. W hW K 31c + K a2 (14) "Ti a- xa z x x2 z z2

139

ii,
where

C - SS concentration

V u Flow velocity in pond surface

"W -Mean settling velocity of solid particle

K - Diffusion coefficient in the horizontal direction

x

Ki -Diffusion coefficient in the vertical direction

From the exact solution of Equation 15, we can obtain the SS concentration of

spill water as follows:

CA Co 16 b2A2nV2n + 1 e...

n-I h(Q2 n + b2)2[(12n + b2 )h + 2b] 2n + + a)

U Kx

aK 2 I _tw2K

" x z

K

w Z 12 2

Z U /K + w/K (5

u,/K h -2 + w/K K I

2 K

2X• b

tan Xnh 2 2 ., X2n - b2

In this case, it i convenient to include 'he concept of a removal coefficient as R - CA/Co. This coefficient depends upon sediment properties and

* pond conditions. Figure 5 show6 zome relationships between R and settling

velocity W . Figure 6 shows some relationships between R and pond length.

In the treatment of dredged material, the required value of R is set in

each case. Roughly speaking, a reasonable value in a settling pond is about

2 x 10 . If the required value of the project is expected to be more than

this value, spill water treatment becomes necessary.

"140

-o
Kxm1OOcmU/lSc Kzulcm/*ISc L.SOOm FE0.06

1.0

8

6

4 c=

2

Hi 30c

4

2

Rt

4

Possible 2 in pond

8

6

4

2

0.005 0.00 0.02 0.04 0.06 0.1 cm/sec

- w

Figure 5.- Relationship between R and settling velocity W

rx-100cm 2

/sec Kz-1cm 2

/sec U-0.01cm/sec F-0.06

1.-0

Ef - 50cm

He 30cm 02

10

Possible

Iin pond

10 He - 20cm

200 400 600 800 1000 1200 m

L

Figure 6. Relationship between R aaxd basin length L

141
0.1 1ix O -1 10- 2 -q R 10 "- 3 0 "' 10 "$

R -R x R2

t t Pond Spill Water Treatment

REMOVAL OF POLLUTANTS

It is clear that the removal of suspended solids aids the removal of pollutants. The efficiency of pollutant removal depends upon the !nLerposing

conditions between solid particles. According to our laboratory tests, the

relationships between the removal efficiencies of SS and pollutants are:

i) PCB

R20 mg/1 03- RSS =20,000 mg/f x1

7 = 1.5 x 10-

(PCB concentration in sediment =750 mg/kg, void ratio =5, sediment

content - 10%)

ii) Hg

R - 18 mgl 0.9 M 10-3

RSS =20,000 mg/L

RHg B 1.78 7 lig/l mg/ 39x1 1

(Hg concentration in sediment - 278 mg/kg, void ratio = 5, sediment

ctntent - 10%)

iii) Oily substances

R 50.8 mg/1 _

RSS "4'6,450 mg/1 . x 10- R 4.6 6 ,L. .9 X 102

Roll 243 m81g/L 1 x

(Hg- concentration in sediment - 38,000 mg/kg, void ratio s5, 

stfrvent content %0%)

142"

iii) Oilysubsance

~~9~m/t 1.1 /

oil. . . 6. . . . 9. .io2• . . . . m m ~ m m
As Figure 7 shows, the removal efficiencies of SS f or the three samples

are nearly equal, showing the value of 1 x 103 However, the removal efficiencies of pollutar.s are different, showing the values of 1.9 x 10- to

3.9 x 03

PCB H9

Rs s

10- 10-3

R of Pollutant

Figure 7. Relationships between removal efficiencies

of SS and pollution

Here we take the ratio of R to R of pollutants: ss

PCB -. 5x 1.5

I x 10O

3.9 x 103

Hg = 0.9 x 1 -3 4.3

il-1.9 x 10 2- 0.1

Ol-1.1 x 10 3 01

The smaller the ratio, the larger the difficulty of removal of pollutants. From this point of view, the removal of oily substances is the most

difficult. Among these pollutants, the reduction of mercury concentrations is

the least difficult.

143
CONCLUSIONS

As mentioned, the settling tube test is the most popular method for planning settling ponds and spill water treatment. However, it seems that there

is some doubt about the correct evaluation of test results. We believe that

our theoretical analysis of this problem would be useful in making this correct evaluation.

14I

144 '

lw
ST. LAWRENCE SEAWAY PRECISE NAVIGATION

David C. N. Robb

Deputy Director for Engineering Research and Planning

Office of Plans and Policy Development

Saint Lawrence Seaway Development Corporation

BACKGROUND

The St. Lawrence Seaway (Figure 1) is the deep draft waterway which

serves the North American mid-continent, allowing vessels to overcome the

600-ft elevation difference between Lake Superior and the Atlantic Ocean by

means of a series of 16 locks and associated channel improvements. The Soo

Locks and the St. Marys River channel, connecting Lakes Superior and Huron,

are operated and maintained by the U. S. Army Corps of Engineers, which also

maintains the other channels in the upper Great Lakes. The WelLnd Canal,

which has 8 locks and parallels the Niagara River between Lakes Erie and

Ontario, is operated and maintained by the St. Lawrence Seaway Authority of

Canada. The area of specific concern for this paper is the St. Lawrence River

portion of the system, which comprises the reach from Tibbetts Point, New York

(on Lake Ontario), to Montreal, Quebec, and includes 7 locks--2 U. S. and

5 Canadian.

The Saint Lawrence Seaway Development Corporation (SLSDC) is one of the

operating administrations of the U. S. Department of Transportation, and is a

wholly owned U. S. Government Corporation, responsible for operating and maintaining the U. S. portion of the system. This is accomplished in close coordination and cooperation with our Canadian counterpart, the St. Lawrence Seaway

Authority of Canada (SLSA). Authority for direct coordination is provided for

in the enabling legislation of both entities. The SLSDC is responsible for

navaids and channel maintenance in U. S. waters and for vessel traffic control

in three sectors between Montreal and mid-Lake Ontario. Canadian navigation

aids are provided by the Canadian Coast Guard, while the SLSA operates the

rest of the system, including vessel traffic control in five of the eight sectors between mid-Lake Erie and Montreal. The Seaway entities also set and

enforce vessel speed limits in the waterway for the protection of life and

property.

The SLSDC is financed entirely by user charges, collected in the form of

tolls on vessels and their cargoes. Seaway navaids in U. S. waters are thus

currently financed directly from user charges, and it is reasonable to assume

that any future improvements will be similarly funded.

St. Lawrence River commercial traffic is largely comprised of two types

of vessels--the so-called "Laker" fleet, primarily Canadian bulk carries of

maximum Seaway size, and the "Salties," that portion of the ocean fleet (about

75 percent) which is not constrained by the limiting lock dimensions (width

and length). The maximum Seaway vessel is 76 ft in beam, 730 ft long, and has

a maximum draft of 26 ft. In 1979, a total of 6,363 transits were made at

Eisenhower Lock, comprised of 4,633 commercial transits, 439 noncargo

145

p.. 4
Z4i

to CD oc -

N 0 6

0,,

41

z 5 ca JC,,

4-cX4

0 ca

2C'I

cc~ II j

7 146
transits, and 1,291 transits by pleasure craft. The commercial vessels moved

some 55.3 metric tons of targo through the St. Lawrence River in 1979.

The current navigation season runs from about 1 April to 20 December each

year. The system is thus shut down due to weather and ice conditions for

about 100 days each year.

THE SEAWAY NAVIGATION PROBLEM

Two measures of system performance are important to the operating entities and to the vessel operators. System capacity is the measure of the

ability of the system to move cargo per unit of time and is usually expressed

in transits per day o-- in tons per year. Capacity is normally constrained by

the time required to process a vessel through the slowest lock. However, in

times of low visibility or when floating, lighted navigation aids are not

available in specific channel reaches, the capacity c,' straint shifts to those

reaches. The second performance parameter is vessel transit time required for

negotiation of the Montreal to Lake Ontario section of the Seaway. This translates directly into vessel operating costs.

At the beginning of each navigation seavon the commissioning of floating

lighted aids is delayed up to 4 weeks due to ice in the River, which complicates settling buoys, and which may damage them or move them off station.

Tcward the end of the season the floating, lighted aids must usually be

decommissioned before the close of navigation, again because of ice. There

are also periods throughout the navigation season when visibility is too low

for vessels to proceed safely with the available navigation aids. It is

important to emphasize in this discussion that the Seaway entities are

addressiiig a piloting system as opposed to a surveillance system, such as the

system in operation on the Suez Canal, for example. The accuracy and reliability requirements for pilotage are much more stringent than for surveillance.

In connection with the channel maintenance operation, accuracy requirements

are even more str' tgent, but reliability is not as critical since safety is

not involved.

There are 190 miles of channel between Montreal and Lake Ontario, with 87

course changes and 7 locks. In the 120 miles between Lake Ontario and the

Quebec border, the International Boundary crosses the channel limits some

36 times before it finally leaves the River. Representative minimum widths

between Montreal and Lake Jntario are:

180 ft through two bridge draws in the Beauharnois Canal

220 ft in the South St e Canal

425 ft in the Brockville Narrows

442 ft in the Wiley-Dondero Canal

450 ft in portions of the American Narrows

Some 68 miles or 36 percent of the Montreal-Lake Ontario section has a channel

width of less than 500 ft. The narrowest sections are amenable to the provision of additional fixed aids, which provide the necessary guidance information even in periods of very limited visibility. The wider areas do not lend

themselves to this solution, however, and are prime candidates for an electronic system.

147
Removal of the floating, lighted aids in the fall and the delay of their

commissioning in the spring result in to 5 weeks of daylight-only navigation, with an attendant reduction of about 75 percent in system capacity and

an approximate 100 percent increase in the normal 22- to 24-hr transit time

between Montreal and Lake Ontario. An additional 8 to 10 days is lost due to

delays during the normal season, for a total economic loss to the Seaway user

of about $10 million in increased operating costs due to vessel delays. Full

. recovery and utilization of the annual lost capacity could result in revenue

increases on the order of $10 million per year to the two Seaway entities.

Thus, provision of a true, all-weather navigation system on the St. Lawrence

River could, in the ideal case, capture annual benefits of up to $20 million,

which would be divided about equally between the users and the operating

entities.

The availability of a Precise Navigation System is considered by the two

Seaway entities to be an essential prerequisite to any extension of the navigation season. However, as is obvious from the above, the need for such a

system is clearly justified within the context of firming up the existing

navigation season, and is being pursued fuK that reason.

The provision of navigation aids and vessel traffic control services has

significant legal implications with respect to potential liability on the part

of the entities for the safety of the vessel, their contents, and their crews.

These implications must be considered when contemplating any changes in the

services provided. Ideally, some means for a vessel master to verify the

*. accuracy and reliability of his guidance information should be provided so as

not to infringe upon his responsibility for the safety of his vessel.

CURRENT STATUS

An international, interagency steering committee, comprised of the two

Seaway entities and the two Coast Guards, was established 2 years ago to

formalize the mechanism for coordination and cooperazion on the Seaway precise

navigation problem. This arrangement builds on the significant experience of

the U. S. Coast Guard with LORAN-C piloting systems, for COGLAD on up to PILOT

and PLAD, which have been demonstrated rather extensively on the St. Marys

River, between Lakes Superior and Huron, and on Delaware Bay, respectively.

Major tasks for the group include:

a. Definition of system accuracy and reliability requirements.

b. Examination of the potential role of LORAN-C.

c. Survey of other candidate positioning systems.

d. Development of requirements for the shipboard display unit.

e. Recommendations to management on a Seaway Precise Navigation System.

148

V
*! PRELIMINARY CONCLUSIONS

Preliminary conclusions include:

a. The St. Lawrence Seaway precise navigation problem t s relatively

unique and technically demanding.

b. No single electronic positioning system currently available can provide the necessary combination of accuracy and reliability required

to allow all-weather vessel movements throughout the Montreal-Lake

Ontario portion of the system in the absence of conventional navigation aids.

c. The current accuracy requirement is estimated by the Seaway entities

at just under ±25 ft, absolute.

d. The accuracy and reliability requirements for a replacement system

must be expressed in absolute, rather than probabilistic, terms since

no vessel master can be asked to subject his vessel to a 5 percent or

even a 1 percent probability of grounding or collision.

e. To Leet stringent Seaway reliability requirements, a combination of

additional conventional aids (more ranges and fixed lights) and two

or more additional systems will most likely be needed.

f. Radar will likely be one of the component systems, and an integrated

"display is highly desirable, if not required, for user acceptance.

Based on preliminary results of ongoing grid monitoring and field testing

activities, it is clear that, even with some form of differential corrections,

the present Northeast LORAN-C chain cannot provide the accuracy necessary for

'-" safe navigation in the Montreal-Lake Ontario section of the St. Lawrence River. . However, installation and operation of a LORAN-C transmitter north of the

"River could significantly improve grid geometry to the point that LORAN-C

might provide the necessary accuracy.

We have beer, unable to identify any other currently available, off-theshelf system capable of solving the problem, although a number of available

*- systems could provide useful supplemental information to the St. Lawrence Sea-

* way navigator.

Systems which are examined for their potential contribution include PRANS

*• (Precise Radar Navigation System), Racons (Radar Beacons), MLS (Microwave Land-

*" ing Systems), sonar positioning systems, follow-the-wire systems, various

* electronic positioning systems such as LORAN-C and Raydist-T, several microwave systems, laser systems, and night vision enhancement devices.

The Navstar Global Positioning System (G.P.S.) currently under deployment

* by the U. S. Department of Defense is another candidatL system under

consideration. Utilizing differential techniques, some sources claim to be

able to achieve accuracies on the order of 0.2 m with G.P.S. Accuracies at

this level would make G.P.S. a prime candidate for both precise navigation and

maintenance uses.

149

d
"MEASUREMENT OF NUTRIENT CONCENTRATIONS IN SEDIMENT PORE

WATER COLLECTED BY A DIALYSIS SAMPLER

* .Y. Kurimoto, Chief Engineer

T. Kotake, Chief Engineer

Japan Bottom Sediments Management Association

15 Sankyo Bldg 7-12, Tsukiji 2-chome, Chuo-ku,

Tokyo 104, Japan

ABSTRACT

In the release mechanism of nutrients it sometimes becomes necessary to investigate the behavior

"of nutrients in sediment pore water. In the past,

the separation of pore water from sediment has been

performed using the centrifuge or a filter press

"procedure. These methods release nutrients dynamically by artificial forces duri 4 water separation.

However, the release action is static in nature.

Differences in the release action of nutrients from

sediment pore waters using a dynamic (centrifuge)

. versus a static (dialysis) method will have a large

effect on the results. Dynamic separation methods

* may not accurately reflect the actual static

nutrient release processes occurring in nature. To

solve this problem, a static separation was developed using a dialysis sampler. This paper discusses results obtained from such a sampler tested

"in a Japanese lake and a bay.

PORE WATER SAMPLER

"The pore water sampler used (Figure 1) was manufactured in Japan according to Mayer (1976). It consists of an acrylic cylinder 60 mm in diameter and

715 mm long, perforated with 10-mm holes on its surface.

The cylinder is divided into six chambers, into which dialysis bags are

placed (Figure 2). The sampler is inserted into the sediment and left until

the deionized water inside the dialysis bag reaches equilibrium with the pore

"water of sediment (Figure 3). Then, the sampler is withdrawn and the pore

water is analyzed.

MEASURED VALUES OF NUTRIENT CONCENTRATIONS

Measurements of nutrient pore water concentrations were conducted at two

locations, Kasumiga Lake (three samples) and Mikawa Bay (two samples). Additional comparisons were made with sediment samples collected at the same location as those of the pore water (dialysis) samples. These samples were

analyzed by conventional methods using centrifugal separation. The results of

these analyses are shown in Tables I and 2.

150
iMMI'.. F

- - 7 , _ _ _ .. .__

c, 

100 Virv I. 0

Water

Sediment D

Dialysis Sag

Figure 1. Dialysis sampler developed Figure 2. Pore water

by Mayer (1976) sampler used

Screwed

00a

0 

4

*waScrewed a

sie Sediment

00 .7 Dialysis Bay

.•0 nylo th ead

0 

'

00

Fill bag with deionized

p~p. water and separate into

six compartments with

nylon thread.

Figure 3. Preparing membrane

'51
I.

k

TABLE 1. NUTRIENT CONCENTRATIONS IN PORE WATER AT KASUMIGA LAKE

"19 Sept. 1981 29 Sept. 1981 5 Oct. 1981

Centrifuge, mg/1 Dialysis, mg/t Dialysis, mg/i

P0-P NH4-N - PO-P NH-N - PO-P NH-N -

Depth, cm 4 4 Ct. 4 4 Ci. 4 4 C1.

"Off-Shore Takasaki, Water*

10-20 - - - 0.017 0.04 12 - -

0-10 - - - 0.014 0.14 10 - -

Off-Shore Takasaki, Sediment

0-10 0.01 14.9 22 0.011 1.20 12 - -

10-20 0.024 10.5 24 0.008 1.18 12 - -

20-30 0.030 8.65 24 - -

30-40 0.76 7.35 27 - -

On-Shore Kawaguchi, Water*

10-20 - - - 0.008 0.11 29 0.026 0.63

"0-10 - - - 0.014 0.43 29 - -

On-Shore Kawaguchi, Sediment

0-10 0.014 34.2 41 0.008 16.3 27 - - -

10-20 0.014 53.3 40 0.008 33.0 29 0.017 33.3 -

20-30 0.060 72.7 43 0.011 40.0 28 0.045 40.4 -

"30-40 0.235 75.8 53 0.012 43.2 30 - - -

* Water depth expressed as sample collection point relative to sediment

surface.

TABLE 2. NUTRIENTS CONCENTRATIONS IN PORE WATER AT MIKAWA BAY

11-31 Aug. 1981 9-23 Dec. 1981 18-25 Feb. 1982 31 Aug. 1981

"Dialysis, mg/i Dialysis, mg/it Dialysis, mg/_. Centrifuge, mg/i

Depth, cm PO-P NH4-N PO0-P NH4-N PO0-P NH4-N PO-P NH4-N

Depth, cm 4 4 4 4 4 4 4 4

Water*

10-20 0.516 1.56 - - 0.006 0.22 0.069 0.336

0-10 0.653 2.11 - - 0.010 0.22 0.069 0.391

Sediment

0-10 1.061 2.44 0.08 1.56 0.010 0.33 1.858 6.16

10-20 2.21 9.00 0.525 7.07 0.432 1.55 1.784 7.78

"20-30 2.70 8.74 0.437 2.42 0.634 3.32 1.701 8.12

30-40 1.68 8.07 0.153 2.20 0.759 4.18 1.491 8.53

* Water depth expressed as sample collection point relative to sediment

surface.

152
/

/

The vertical distributions of nutrients in pore water using the dialysis

sampler are indicated clearly in Figures 4 and 5. The concentrations increase

with sediment depth.

It is readily apparent that the two nutrient depth profiles depicted in

Figures 4 and 5 show similar patterns of increasing concentration with depth.

The profile depicted describes the close relationship generally associated

with nutrient release behavior in sediment pore water.

20 20

Q 10 $4 W4 Q1

0 1141NH1-N, mg/9. 4-

10 20 30 40 50 0.2 0.4 0.6 0.8

0 0

10 10

4J 20 . 20

U 30 30 ha 0

40 40

Figure 4. NH 4-N in pore water Figure 5. PO4 -P in pore water

at Kasumiga Lake at Mikawa Bay

COMPARISON OF CELTRIFUGE AND DIALYSIS SEPARATIONS

Differences between centrifuge and dialysis separation methods for

Kasumiga Lake sediment are shown in Figure 6.

As the figure shows, the measured concentrations from centrifuge separation are larger than those using the dialysis sampler. This suggests that

nutrients are released dynamically during the centrifuge separation. Therefore, the centrifuge method does not suggest an accurate measure of the

nutrient concentrations actually found statically in sediment pore waters in

nature.

Figure 7 illustrates graphically the differences between the centrifuge

method and dialysis method over a range of PO 4-P concentrations measured in

sediwent pore waters. The larger the magnifying power, the smaller the PO4-P

concentrations. The magnification for NH4-N is shown in Figure 8. It behaves

the same as PO -P. In 1983 we conducted the same tests in Tokyo Bay. Figures 9 and 10 indicate the magnifying powers for Tokyo Bay sediment. As the

figures show, the magnifying power curves for Tokyo Bay sediment behave the

"153

i • ,i!I
• /

NH, -N, MG/f

20 40 60 90

0

a.

w

20

30 KASUMIGA LAKE

40,

Figure 6. Comparison of NH 4-N from centrifuged

and dialysis separated sediments

from Kasumiga Laka

2.0

2

"1.0

0 __

0.1 PO 4-P, Mr.19 2 3

Figure 7. Magnifying powe:r ratio

"Centrifuge for

"Dialysis 4

same as the ones observed in this paper. Therefore, we have come to believe

that the large differences between the two methods might be caused by dynamic

release during the centrifuge separations.

THEORETICAL CONSIDERATIONS ON VERTICAL DISTRIBUTION OF

Lr NUTRIENTS IN PORE WATER

In Figures 11 and 12, the vertial distributions of nutrient concentra-

"tions in sediment are indicated.

k 1

4. 154

4.
3.0

MIKAWA BAY

KASUMIGA LAKE

Z2.0

2

z

I I II II I I

2 3 4 5 10 20 30 40 50

NH4 -N. MG/Q

Figure 8. Magnifying pover for NH 4-N

5

4

TOKYO SAY

3

MIKAWA BAY

2

0U

00.1 .. I , i II

0.1 1 2 3 4 5

PO4 -P. DIALYSIS, MG12

Figure 9. P04.-P in Tokyo Bay 45

155
7

6

TOKYO BAY

5

4

3

KASUMI LAKE

2 MIKAWA BAY £

01

5 10 20 30 40 100

NH4 -N. DIALYSIS,MG/i

Figure 10. NH4 -N in Tokyo Bay

T-N, mg/kg

1000 2000 3000 4000 5000

10

0

soo

20

40

500

Figure 11. Vertical distribution of T-N

in Mikawa Bay sediment

156
T-P,..mg/kg

0 1000 2000 3000 4000 5000

10

20

0

S40

50 L

Figure 12. Vertical distribution of T-P

in Kasumiga Lake sediment

We can assume that the profile of nutrient distribution Ps i a parabolic

curve as follows (also see Figure 13):

2

'B - Z)

PS " PB + 2f mg/kg (1)

p

where

PB = concentration at the point where the curve becomes vertical

ZB - sediment depth corresponding to PB

f - coefficient of parabola p

The quantities of nutrients W , which are contained in the small depth dz

at depth Z , are represented as follows (in milligrams):

W(Z) 0.0026 rp (ZB+ z) (2) "1 + eo Fdz B 2 fp(

where e0 - void ratio of sediment.

The quantities of released nutrients, which partition from the above

mentioned portion, are represented as follows (in milligrams per day):

157
0.0026 +_2______ 1W + F•dz B+ (3)

where

= partition coefficient -1

day

0

z -DI/

dz-

=-PB

z

Figure 13. Profile of a nutrient

The equilibrium equation of nutrients at depth z becomes as follows:

ac 0.0026 + +. 2] 2c

S1 +e e [PB 2f ] • 2 (41%

where D - diffusion coefficient of nutrient particles in the vertical

direction. if we put here

I 0.0026

1 +e0

Equation 4 becomes

158
z2 - D-- P +(5 2 B 2

As equation 5 is an irreducible partially differential equation, the

solution can be written as follows:

2 2

C u Aei D-t + bi Oz (6)

The particular integral becomes

[P (Z6-)Z

C = f- + 2f dZodz

p -f [P•z 6f dz (7)

p "-D .•[PZ+ 24f J

Hence, we have the following equation:

Cm Ae i a[IPZ2 + 2Z4;z J (8)

The first term on the right side of Equation 8 is an exponentially increasing

function; the second term is a decreasing function with regard to Z

Figure 14 shows the theoretical distribution calculated by Equation 8 for

Kasumiga Lake sediment. There is a good agreement between calculated and

measured profiles. This verifies the hypothesis adopted in the preceding

calculation.

159 /

'~~~~~~~~ I- -• - - - - -I - - iI - - -I
T-P, 9g/1

0 4 6 8 10 12

10

20

U • Calculated

30

6 SMeasured 

40

50

Figure 14. Comparison of measured and calculated values

CONCLUSIONS

Japan was the first country to study measurements using the Mayer (1976)

dialysis sampler. These studies gave good suggestions for release mechanisms.

It has been concluded that nutrient concentrations in pore water shoulV be

measured by such a sampler, and that the conventional method of using a

centrifuge is not suitable.

160
ACCUMULATION OF ACRYLAMIDE INTO FISH

J. Asada, T. Shimizu, S. Tajima,

F. Sakamoto, M. Fujiki

Department of Environmental Health

School of Medicine, University of Tsukuba

1-1-1 Tennoodai, Sakura-mura, Niihari-gun,

Ibaraki-ken 305, Japan

ABSTRACT

The accumulation of acrylamide monomer and

polymer into fish and the behavior of acrylamide

monomer in the aqueous environment were investigated.

Red sea bream and carp were used as experimental fish.

Fishes were placed in fish-rearing tanks with fresh

water and/or seawater containing acrylamide monomer

and/or polymer and were reared for 25 days. The

accumulation of acrylamide monomer into red sea bream

from seawater c.ontaining 10 ppm acrylamide monomer

reached 1.2 ppm after 20 days. Acrylamide monomer

accumulated in organs of carp from water by the following factors: liver--0.5, kidney--0.5, gills--0.15,

muscle--O.'7, and blood--O.19. The degradability of

acrylamide monomer in tap water and distilled water

was slight. Approximately 90 percent of the acrylamide monomer in seawater and pond water was degraded

after 14 days. Acrylamide monomer in fish 3reeding

water decreased to undetectable levels in 5 days.

From this experiment, it was clear that the rate of

accumul .- on of acrylamide into fish was slight, and

acrylamide monomer in environmental water was easily

degradable.

INTRODUCTION

Acrylamide polymer is widely used as a coagulant for treatment of

industrial wastewater, domestic sewage, effluent of reclamation, sludge, and

dredging work, etc. The toxicity of acrylamide polymer is slight, but

acrylamide monomer contained in polymer as a contaminant is neurotoxic. The

use of acrylamide monomer in a coagulant invites serious problems for human

health. The toxicity of acrylamide monomer is well known and many papers have

been written (1-15). However, there are few reports on the biodegradability

and the bioaccumulation of acrylamide monomer, and an analytical method of

acrylamide monomer accumulation in fish tissue was not known previously.

Therefore, it is important to understand the behavior of acrylamide monomer

contained in coagulant on the environment. The authors of this paper have

investigated analytical methods for acrylamide monomer in tissue and the

accumulation of acrylamide monomer in carp and killifish. These results were

161
reported at the meeting last year (16). In order to determine the behavior of

"acrylamide monomer in the environment, bioaccumulation and biodegradability

"were investigated in this paper.

ACCUMULATION OF ACRYLAMIDE MONOMER AND POLYMER IN FISH

"Experimental Method

Red Sea Bream (Chrysophry8 major)

Red sea bream (length: 15.0-20.0 cm, weight: 60-100 g, age: 2 years)

were used. One thousand litres of filtered seawater was poured into two

"1000-L fish-rearing tanks (A and B, respectively). Ten grams of acrylamlde

monomer was added to tank A (10 ppm) and 20 g of acrylamide polymer was added

to tank B (20 ppm, containing 0.002 ppm of monomer). Thirty red sea bream

were put into each tank and reared for 25 days without feeding. Aeration was

continued during the experiment. Rearing water was replaced with frech pre-

"- pared water containing acrylamide every day.

Five hundred litres of filtered seawater was poured into a 500-L fish-

",- rearing tank (C) and 15 red sea bream were put into tank C and reared for

' 25 days without feeding. Tank C was used as a control. Aeration was continued during the experiment. Rearing water was replaced with fresh prepared

water every day. Water temperature was maintained at 17-22*C during the

experiment.

Five red sea bream were selected from each tank at days 0, 5, 10, 15, 20,

and 25. Each sample nf fish was homogenized and the concentration of

acrylamide monomer in the homogenate was measured by the method described

below.

Red sea bream was cut up and placed in a homogenizer with distilled water

"* equivalent to the weight of fish and homogenized. A known weight of

homogenate was taken and the volume of homogenate was adjusted to 50 ml by

addition of distilled water. The pH of the homogenate was adjusted to I by

addition of 6 N sulfuric acid. Fifteen grams of potassium bromide was added

to the homogenate and the homogenate was stirred until the potassium bromide

"dissolved completely. Then 10 ml of 0.1 M potassium bromate was added to the

homogenate, the homogenate was transferred co the refrigerator (5"C)

". immediately, and the homogenate was stored for 30 min. After bromination

*: (Figures 1 and 2), bromine remaining in the homogenate was removed by addition

of I M sodium thiosulfate solution. The homogenate was centrifuged for 2 min

at 3000 rpm at 5°C; the supernatant was transferred to a separatory funnel;

*" 50 ml of benzene was added to the supernatant; and the separatory funnel was

shaken for 15 min. The benzene layer was separated from the water layer. The

benzene layer was transferred to another separatory funnel; 50 ml of distilled

water was added to the benzene layer; and the separatory funnel was shaken for

15 min. The water layer was then separated from the benzene layer. The water

.- layer was transferred to another separatory funnel; 50 ml of ethylacetate was

added to the water layer; and the separatory funnel was shaken for 15 min.

* The ethylacetate layer was then separated from the water layer. The

concentration of 2,3-dibromopropionamide (DBPA) formed by bromination of

acrylamide monomer was measured by gas chromatograph and the concentration of

*162
0 -( CH-CH)XCH 2=CH-C-NH2 CONH2

, acrylamide molecule Polyacrylamide

(monomer) (Polymer)

Figure 1. Structure of acrylamide monomer and polymer

H H H H H H

I I I I I I

-- H-C=C-C-N-H iI -.----- K3r "--.. )i H-C-C-C-N-H I II

o.1 M-••ro 3 Br Br 0

acrylamie2 3-d ibromopropionamide

(DBPA)

Figure 2. Bromination of acrylamide monomer

acrylamide monomer in the fish tissue was calculated from the concentration

of DBPA. The rate of recovery for acrylamide monomer by this method is shown

in Table 1.

A gas chromatograph with electron capture detector (Shimadzu GC-7A) was

used with a glass column (length: 1000 mm, diameter: 3 mm) packed with Silicone OV-275 (2%. support: Chromosorb W. 80-100 mesh). Column and detector

• temperatures were 175"C and 190"C, respectively. Nitrogen gas was used for

"* carrier gas and the flow rate was 35 al/min.

TABLE 1. RATE OF RECOVERY OF ADDED 10 ppa ACRYLAMIDE

MONOMER TO HOMOGENATE OF FISH TISSUE*

Rate of recovery 12.96%

12.13

12.95

11.19

11.07

Mean 12.06

Standard deviation 0.91

Coefficient of variation 7.56

• Extraction: benzene-water-ethylacetate.

163
"Carp (Cyprinus carpio)

Carp (length: 15.0-20.0 cm, weight: 80-100 g) were used. Forty litres

of distilled water was poured into three 40-1 fish-rearing tanks (D, E, and F,

respectively). Four hundred milligrams of acrylamide monomer was added to

tank D (10 ppm) and 2000 mg of acrylamide monomer was added to tank E

(50 ppm). Tank F was used as a control. Thirty carp were put into each tank

"and reared for 20 days without feeding. Carp in tank D were reared for an

additional 5 days without feeding after the experimental dosing with

, acrylamide monomer ended.

Aeration (600 ml/min) was continued during the experiment. Rearing water

- was replaced with fresh prepared water containing acrylamide every day. Water

temperature was maintained at 200-22*C during the experiment. Three carp were

selected from each tank at days 0, 5, 10, and 20. The liver, kidney, gills,

muscle, and blood of these carp were homogenized separately and the

concentration of acrylamide in the homogenate was measured by the method

described as follows.

Organs without blood were cut up and placed in a homogenizer with

"distilled water equivalent to the weight of tissue homogenized. A known

weight of homogenate was taken and the volume of ho:osgenate was adjusted to

50 ml by addition of distilled water. The pH of the homogenate was adjusted

. to I by addition of 6 N sulfuric acid. Fifteen grams of potassium bromide was

added to the homogenate and the homogenate was stirred until the potassium

*[- bromide dissolved completely. Then 10 ml of 0.1 M potassium bromate was added

* to the homogenate; the homogenate was transferred to the refrigerator (5"C)

* immediately; and the homogenate was stored for 30 min. After bromination,

bromine remaining in the homogenate was removed by addition of I M sodium

thiosulfate solution. The homogenate was centrifuged for 2 min at 3000 rpm at

5"C; the supernatant was transferred to a separatory funnel; 50 ml of

"* ethylacetate was added to the supernatant; and the separatory funnel was

* shaken for 15 min. The ethylacetate layer wai then separated from the water

* layer. The concentration of DBPA in the ethylacetate layer was measured by

gas chromatograph and the concentration of acrylamide monomer in the fish

*. tissue was calculated from the concentration of DBPA. The rate of recovery

for acrylamide monomer by this method is shown in Table 2.

TABLE 2. RATE OF RECOVERY OF ADDED 20 ppm ACRYLAMIDE

MONOMER TO HOMOGENATE OF FISH TISSUE*

Rate of recovery 83.4%

"81.1

"83.4

80.2

81.9

Mean 82.0

Standard deviation 1.41

Coefficient of variation 1.72

• Extraction: ethylacetate.

164
Results

The accumulation over time of acrylamide monomer into red sea bream from

seawater containing 10 ppm acrylamide monomer is shown in Figure 3. The

accumulation in red sea bream from seawater increased rapidly until day 5 and

then slowly until day 20 when the concentration of acrylamide monomer reached

1.2 ppm. The concentration factor of acrylamide monomer from seawater to red

sea bream was 0.12.

0.4- I.

0.2

0 5 10 15 20 25

Ti me (days)

SFigure 3. Accumulation of acrylamide in red

sea bream in 10 ppm acrylaide

monomer solution

SThe accumulation over time of acrylamide monomer into red sea bream from

Sseawater containing 20 ppm of i.crylazide polymer was undetectable during this

experimental period. The accumulation over time of acrylamide monomer into

carp organs from water containing 10 and 50 ppm of acrylamide monomer is shown

in Figures 4 and 5. respectively. The accumulation of acrylamide monomer in

ad

carp gills, muscle, adblood from water containing 10 and 50 ppm of

acrylamide monomer ocurdrapidly and reached equilibrium by day 5. The

accumulation intelvradkidney increased slowly and continuously during

the exeietlpro.Teconcentration factor from water to liver was

0., .1, n bo.0.9

0.,kidney 0.5, gills 0.15, muscle0.7anblo019

165

• , ' , I I i I I I I I lU
5•

4-

Ea 00ij

0 o -- boo A' ,.• muscle

U 2 -

SgiNF t

/ / , -- --

0 5 10 15 20

05

Ti me (dcys)

Figure 4. Accumulation and excretion of acrylamide

of carp organs in 10 ppm acrylamide

monomcr solution

30 . .

- SS

a20 0

ie e

'',

~-10-

0 5 10

Time (dCvs)

Figure 5. Accumulation of acrylamide into

carp organs in 50 ppm acrylamide

monomer

1j "e'"- 166

"I.
I

DEGRADABILITY OF ACRYLAMIDE MONOMER IN AQUEOUS ENVIRONMENT p

Experimental Method

Water

Tap water (from Sakura-mura, Ibaraki-ken), distilled water, seawater

(from coast of Oarai, Katsuta-shi, Ibaraki-ken), pond water (from park

Matsumi, Sakura-mura, Ibaraki-ken), and breeding water (which was used for

rearing of carp) were used in this experiment. Three hundred willilitres of

tap water, distilled water, seawater, and pond water was poured into four

300-ml Erlenmeyer flasks, respectively, and then 3 mg of acrylamide monomer

was added to each flask. Waters in these flasks were stirred during the

experimental period and temperature was kept at 20*C. Breeding water was

prepared by the following method. Ten litres of distilled water was placed in

a 10-i fish-rearing tank with two carp. Then, 100 mg of acrylamide monomer

was added to the tank and temperature was kept at 20*C during the txperimental

period. Concentration of acrylamide monomer in the tap water, distilled

water, seawater, pond water, and breeding water was measured daily.

Carp Tissue

In the experiment on accumulation of acrylamide monomer into carp tissue

from the water containing 10 ppm of acrylamide monomer (tank D), the dosage

was suspended after 20 days and the carp were reared in acrylamide monomer

free water for 5 days. Two carp were taken from tank D at 6 hr, 12 hr, 24 hr,

2 days, and 5 days after suspension of acrylamide monomer dosing. The organs

of these carp were homogenized and the concentration of acrylamide in the

homogenate was measured by the method previously described for carp.

Results

The degradation over time of acrylamide monomer in waters is shown in

Figure 6. Degradability of acrylamide monomer in tap water and distilled

water waq slight. Approximately 90 percent of the acrylamide monomer in seawater and pond water was degraded after 14 days. Acrylamide monomer in breeding water decreased to undetectable levels after 5 days.

In the experiment on accumulation of acrylamide monomer in carp from

water the dosage was suspended after 20 days and the carp were reared in

acrylamide monomer free water for 5 days. Organs of carp used in this experiment were sampled and the concentration of acrylamide monomer in the organs

was measured as above. Variations of concentration over time are shown in

Figure 7. Acrylamide monomer in all organs decreased quickly. After 12 hr,

80 percent of acrylamide monomer in muscle, 70 percent in gills, 60 percent in

blood and kidney, and 50 percent in liver were degraded. After 2 days,

95 percent in muscle, 90 percent in gill, 80 percent in blood, 70 percent in

kidney, and 70 percent in liver were degraded. After 5 days, 90 percent or

more of acrylamide monomer in all organs was degraded.

1b7
o Wstille' wt

~ 0 

(,, Q 

-01

-E a20

0 5 10 15

Time (dcys)

Figure 6. Degradation of acrylamide

(10 ppm) in water

-~10 1 2 3

60

80-

60[

40 1 2 3 4 5

Ti me (days)

Figure 7. Excretion and degradation of

acrylamide in carp organs

168
DISCUSSION

An analytical method of acrylamide monomer in water has been reported by

Croll and Simkins (17), Arimitsu (18), and Nakamura (19). However, an

analytical method of acrylamide monomer in fish was not known previously;

therefore, the authors of this paper have developed and reported an analytical

method for acrylamide monomer accumulated in fish tissue (16). This made it

possible to investigate accumulation in fish and biodegradation in the aqueous

environment. In order to determine the behavior of acrylamide monomer contained in coagulant in the aqueous environment, accumulation of acrylamide

monomer and/or polymer in fish and degradation' of acrylamide monomer in the

aqueous environment were investigated in this study.

The concentration of acrylamide monomer in red sea bream tissue from seawater containing 10 ppm of acrylamide munomer reached 1.2 ppm after 20 days.

The concentration factor was 0.12. This concentration factor was lower than

the concentration factor for carp or killiflsh. The concentration factors for

tarp and killifish from water containing 10 ppm acrylamide monomer after

20 days were 0.26 and 2.53, respectively (16). Body length and weight of red

sea bream, carp, and killifish used in the accumulation experiments were

10-20 cm and 60-100 g, 6-20 cm and 3-35 g, and 2.3-3.3 cm and 0.25-0.29 g,

respectively. The concentration factor for large fish was low and for small

fish was high (Figure 8). Body weight of red sea bream was related to the

concentration of accumulated acrylamide monomer (Figure 9). In this case, the

coefficient of correlation was -0.66. From these results, it was concluded

that acrylamide monomer was taken up through the surface of the fish's body.

2.5-

S2.0

0

E c1.51.

• C.

U

0. 5 carp

sabream

0 5 10 15 20

Ti me (days)

Figure 8. Accumulation of acrylamide into

fish in a 10-ppm acrylamide

monomer solution

169
1.5

LS

F 1.0 s "t " 3

+,...0S.o \\

0 S

0 50 100

Weight(g)

Figure 9. Relationship between body

weight of fish and concentration of accumulated

Concentration factor of accumulated acrylamide monomer in fish was far

smaller than the concentration factor of methylmercury or PCB in spite of the

use of very high concentrations of acrylamide monomer such as 10 ppm in breeding water. The accumulation of methylmercury was reported by Kitamura (20)

who stated that 1.07 ppm of methylmercury accumulated into goldfish body from

water containing 0.003 ppm of methylmercury after 40 daye, giving a concentration factor of approximately 3,500. However, the concentration factor of

acrylamide monomer into fish from breeding water was very small. It seems

that acrylamide monomer is degraded and/or excreted quickly by organisms.

Therefore, biodegradability experiments were conducted. Acrylamide monomer in

tap water and distilled water did not decrease significantly; acrylamide

monomer in natural seawater and pond water decreased significantly after

7 days; and acrylamide monomer in breeding water in fish-rearing tanks with

carp decreased quickly and became undetectable after 5 days. Tap water and

distilled water did not contain organisms; however, natural seawater and pond

water contained various microorganisms and the breeding water contained

various microorganisms and carp. From these facts, it was indicated that

organisms in an aqueous environment contribute to degradation of acrylamide

monomer and body organs of the carp also contribute to degradation of

acrylamide monomer.

After suspension of the acrylamide monomer dosage, the concentration of

acrylamide monomer in carp muscle decreased rapidly, the concentrations in

kidney and liver decreased slowly, and the concentrations in blood and gills

were between kidne- and muscle. It seems that acrylamide monomer is carried

by blood, metabolized by liver, and excreted by kidney. The concentration

170
factor of acrylamide monomer for fish is small, and the rate of metabolism and

excretion is rapid.

CONCLUSIONS

This investigation has shown that the concentration factor of acrylamide

monomer for fish from water containing 10 ppm of acrylamide monomer is very

small and the concentration of acrylamide monomer in fish from acrylamide

polymer is undetectable. Acrylamide monomer is rapidly degraded by organisms

in an aqueous environment. Therefore, it is concluded that the use of

acrylamide polymer as a coagulant may not cause serious problems for environmental health.

R-FI AENCES

(1) Peter, S. S., and Herbert, H. S. 1974. "A Review of Acrylamide

Neurotoxicity; Part I, Properties, Uses, and Human Exposure," Canad. J.

Neurol. Sci., Vol 1, pp 143-150.

(2) Peter, S. S., and Herbert, H. S. 1974. "A Review of Acrylamide

Neurotoxicity; Part II, Experimental Animal Neurotoxicity and Pathologic

Mechanisms," Canad. J. Neurol. Sci., Vol 1, pp 152-169.

(3) Pamela, M. F. 1969. "Electrophysiological and Histological Observation

on Peripheral Nerve in Acrylamide Poisoning in Man," J. Neurol.

Neurosurg. Pschiat., Vol 32, pp 186-192.

(4) Herbert, H. S., Henryk, M. W., and Peter, S. S. 1974. "Ultrastructural

Studies of the Dying-Back Process; I, Peripheral Nerve Terminal and Axon

Degeneration in Systemic Acrylamide Intoxication," J. Neuropathol. Exp.

Neurol., Vol 33, pp 260-284.

(5) Richard, J. L., and William, E. R. 1969. "Physiologic and Pathologic

Changes in Acrylamide Neuropathy," Arch. Environ. Health., Vol 18,

pp 22-29.

(6) Prineas, J. 1969. "The Pathogenesis of Dying-Back Polyneuropathies; II,

An Ultrastructural Study of Experimental Acrylamide Intoxication in

the Cat," J. Neuropath. Exp. Neurol., Vol 28, pp 598-621.

(7) Pamela, M. F., and Baners, J. M. 1966. "Peripheralneuropathy in Rats

Produced by Acrylamide," Br. J. Ind. Med., Vol 23, pp 210-221.

(8) Tilson, H. A., and Cabe, P. A. 1979. "The Effects of Acrylamide Given

Acutely or in Repeated Doses on Fore- and Hindlimb Function of Rats,"

Toxicol. Appl. Pharmacol., Vol 47, pp 253-260.

(9) Jennekens, F. G. I., Veldman, H., Schotman, P., and Gispen, W. 1979.

"Sequence of Motor Nerve Terminal Involvement in Acrylamide Neuropathy,"

Acta. Neuropathol., Vol 46, pp 57-63.

171
(10) Hopkins, A. P., and Gilliatt, R. W. 1971. "Motor and Sensory Nerve

Conduction Velocity in the Baboon: Normal Values and Changes During

Acrylamide Neuropathy," J. Neurol. Neurosurg. Psychiat., Vol 34,

pp 415-426.

(11) Hopkins, A. P., and Lambert, E. H. 1972. "Conduction in Unmyelinated

Fibers in Experimental Neuropathy," J. Neurol. Neurosurg. Psychiat.,

Vol 35, pp 163-169.

(12) Albert, S. K. 1958. "Effects of Acrylamide on the Central Nervous

System of the Cat," J. Pharmacol. Exp. Therap., Vol 123, pp 180-192.

(13) Richard, D. H., Ivy, L. Vyas, Herbert, E. L., and Thomas, M. A. 1980.

"The Etiology of Toxic Peripheral Neuropathies: In Vitro Effects of

Acrylamide and 2,5-hexanedione in Brain Enolase and Other Glycolytic

Enzymes," Brain Research, Vol 202, pp 131-142.

(14) Asbury, A. K., Cox, S. C., and Kanada, D. 1973. " 3H-leucine

Incorporation in Acrylamide Neuropathy in the Mouse," Neurology, Vol 23,

pp 406.

(15) Peter, S., Lucy, G., Frans, G. I. J., and Willem, H. G. 1978.

"Polyneuropathies and CNS Protein Metabolsim; III, Changes in Protein

Synthesis Rate Induced by Acrylamide Intoxication," J. Neurc.athol. Exp.

Neurol., Vol 37, pp 820-837.

(16) Fujiki, M., Asada, J. and Shimizu, T. 1982. "Studies on Analytical

Method of Acrylamide Monomer and Accumulation Into Fish," Proceedings of

the 8th U.S.-Japan Expert's Meeting on Management of Bottom Sediments

Containing Toxic Substances, published by U. S. Army Engineer Waterways

Experiment Station, CE, Vicksburg, Miss.

(17) Croll, B. T., and Simkins, G.M. 1972. "The Determination of Acrylamide

in Water by Using Electron Capture Gas Chromatography," Analyst, Vol 97,

pp 281-288.

(18) Arimitsu, H. 1974. "Estimation Method of Microacrylamide in Water,"

Journal of Japan Water Works Association, Vol 473, pp 10-17.

(19) Nakamura, H. 1977. "The Determination of Trace Acrylamide in Water and

Sludge," Journal of Japan Water Works Association, Vol 514, pp 37:40.

(20) Kitamura, M., Kondo, M., Takizawa, Y., Fujii, M., and Fujiki, M. 1981.

"Suigin," p 266, Kodansha, Tokyo.

172
LONDON DUMPING CONVENTION UPDATE

Robert M. Engler

Environmental Laboratory

U. S. Army Engineer Waterways Experiment Station

P. 0. Box 631, Vicksburg, Miss.

BACKGROUND

The Convention on the Prevention of Marine Pollution by Dumping of Waste

and Other Matter--known as the London Dumping Convention or LDC--was negotiated in London in November 19M2. After ratification by 15 member nations,

the LDC came into force in the United States on 30 August 1975.

The policy, regulc.tory, and technical aspects of the Corps of Engineers'

and the U. S. Environmental Protection Agency's (EPA) ocean Jumping programs

for dredged material are directly affected by the United States being signatory to the LDC. Domestic criteria must, at a minimum, be equivalent to and

contain all of the basic constraints set forth in the international

regularions.

The contracting nations have met annually since LDC-I met in September

1976. At that time, an extensive program of work was adopted related to the

implementatior of the Convention concerning all aspects of dumping at sea

(including the dumping of dredged material).

A Scientific Group was formed to make technical and scientific recommendations to the LDC concerning the ecological aspects of regulating dumping at

sea. The group met in September 1977 and has since met annually approximately

6 months prior to each annual LDC meeting.

A Task Team 2000 has been organized to identify long-term goals of the

LDC. The team's specific objective is to project the role of the Convention

in the Year 2000.

The Deputy Director for the Directorate of Civil Works of the Office,

Chief of Engin ers (OCE), attends the annual meetings of the LDC as the Corps'

policy representative. Dr. Robert M. Engler of the U. S. Army Engineer Waterways Experiment Station (WES) is the Corps' technical representative at both

LDC and Scientific Group meetings.

LDC-VII

The LDC-VII met in London on 14-18 February 1983. Delegates from 32 of

the 52 contracting nations were present. There were also 14 observer groups

representing countries that anticipate joining the LDC, regional or local conventions, and other parties interested in the international regulation of

ocean dumping of waste materials.

The 16-member U. S. delegation to the Convention was headed by Dr. John

Hernandez of EPA. The other members of the delegation, who acted as advisors

173
to Dr. Hernandez, were representatives from the Department of State, the House

of Representatives, the Corps (OCE and WES), and the National Oceanic and

Atmospheric Administration.

The comprehensive agenda addressed all aspects of ocean dumping and pollution. Agenda items significantly affecting the Corps' dredging and disposal

projects were consideration of the report of the September 1982 meeting of the

Scientific Group, the report by Task Team 2000, and the discussion of the possible prohibition nf ocean disposal of all low-level radioactive materials.

These are discussed in the following paragraphs.

Scientific Group Report

Two major items from the report concerned Corps projects: the possible

inclusion of lead on the Annex I list of materials prohibited from ocean disposal as other than trace contaminants, and the use of capping or other special care techniques in ocean disposal of contaminated sediments. The issue

of inclusion of lead was scheduled to be resolved technically at the meeting

of the Scientific Group in October 1983 and to be acted upon at the policy

level by the LDC-VIII in February 1984. At present, lead is an Annex II material that is not prohibited from ocean disposal, but must be given special

care when disposed in significant amounts. Dredged material contains high

natural background levels of lead (in comparison to mercury and ca.mium, which

are prohibited by Annex I) and thus inclusion of lead in Annex I could result

in significant practical problems in implementing the LDC. Moreovcr, lead is

generally stable in dredged material and the marine environment.

The LDC-VII was also asked by the Scientific Group to consider whether or

not dredged material contaminated with Annex I (prohibited) substances can be

capped with clean material under the provisions of the LDC. It was generally

agreed that capping techniques should be studied as field research and projects monitored until sufficient information is obtained as to the acceptabil- " -

ity of capping from a scientific viewpoint. The Corps' research under the

Environmental Effects of Dredging Program (EEDP) will continue to assess the

technical applicability of capping in various aquatic environments. At some

future meeting of the LDC, the full legal acceptability of capping will oe

debated with a goal of modifying the LDC rules and regulations if capping

proves technically feasible.

Task Team 2000

The general finding of the Task Team was that the ultimate goal of the

LDC could be stated quite simply as to "protect the marine environment." Fowever, the team did not regard the attainment of such a goal in the black and

white terms of opting either to eliminate any ocean dumping activity or to

control waste disposal at sea. it was, however, recognized that for some

categories of waste, ocean disposal would continue to be a normal option, for

example, the dumping at sea of uncontaminated dredged material and sewage

sludge. The U. S. delegation endorsed the view that ocean disposal should f

considered as an acceptable alternative disposal technique where the decisit

to utilize ocean disposal is made after assessing alternatives in each

situation.

174

46
Low-Level Radioactive Material

The controversial subject of ocean disposal of low-level radioactive

material was also considered at LDC-VII. Low-level radioactive wastes are

currently Annex II materials that require special care be given the disposal.

The delegates from the island countries of Kiribati and Naru jointly proposed

the absolute prohibition of ocean dumping of all ratioactive waste or matter

regardless of level, form content, or method ot containment. The proposed

amendment to the LDC Annexes would move low-level radioactive waste to

Annex I, which would prohibit ocean disposal. This proposal's absolute and

all-inclusive language could, in its broadest context, be interpreted to include dredged material with natural background radiation. After significant

debate, the proposed amendment was withdrawn and replaced by a nonbindiug

resolution of similar laxuguage submitted by Spain. The resolution was passed

by the LDC with the Unibed States voting againrt the resolution. In conclusion, there is nothing tn the historical language of the LDC, U. S. domestic

regulations, or the recent LDC meeting that changes the fact that dredged

material is considered nonradioactive for the purposes of international or

domestic regulation. The Corps will, however, urge that diedgad material be

formally classified as nonradioactive for the purpuses if regul.ation.

FUTURE MEETINGS

The Scientific Group will meet in London on 24-28 October 1983. Scveral

major technical issues affecting ocean disposal of dredged material will be

discussed: the positions of lead and lead compounds in the annexes to the

LDC; interpretation of the term "trace contaminants"; implemeatation guidelines for Annex II; guidelines for the uniform interpretation of Annex III;

oil in dredged material; and definition of so-called "special care" techniques

for disposal of contaminated dredged material.

The LDC-VIII will meet in London on 14-18 February 1984 and will consider

the policy resolution of the technical issues addressed by the Scientific

Group in the October 1983 meeting and other policy level issues affecting

legal as well as technical implementation of the LDC.

175 175 ']"d.
"ALTERNATIVES TO OPEN WATER DISPOSAL

OF CONTAMINATED DREDGED MATERIAL

C. A. Coch, J. F. Tavolaro, R. F. Krauser, and P. Tischbein

U. S. Army Engineer District, New York

Regulatory Branch

26 Federal Plaza

New York, N. Y. 10278

ABSTRACT

Of the 6 to 7.5 million cubic meters of dredged

material generated each year from the New York Harbor

Area, 2 to 5 percent has been determined to be

unacceptable for unrestricted ocean disposal. Three

disposal options are being studied which could acco--odate this material: use of dredged material as sanitary landfill cover, upland disposal, and containment

areas and islands. In a dewatered state, dredged material could be used as a substitute for traditional

cover material Lt sanitary landfills. Chemical and

engineering tests were performed on representative

dredged material from New York Harbor, and it was

determined that all material is environmentally acceptable and may be economically feasible for this use.

Potential upland disposal areas (barren areas) were

evaluated using environmental and socioeconomic

criteria to eliminate unacceptable sites. Containment

area and island siting criteria were developed to eliminate highly biological productive areas in New York

Harbor from consideration. Further efforts for all

three disposal options are being directed at site availability, social acceptability, and detailed environmental and economic studies. All three options appear

to be technically feasible. Sanitary landfill cover

may prove to be a use of dredged material as a resource.

"However, the most problematic aspects of these disposal

"options involve their social acceptability rather than

technical aspects.

INTRODUCTION

In order to maintain the present volume of ship traffic and tonnage,

almost 7.5 million cubic meters of sediment has been dredged per year from the

Port of New York/New Jersey (NY/NJ) over the past 45 years. The bulk of this

material has historically been ocean disposed. The disposal site is located

in the New York Bight, about 10 km east of Sandy Hook, N. J.

1 i•[176
1. U. *.

The possible adverse environmental impact of the dredged material con-

• taining potentially toxic and hazardous substances originating from treated

"* and untreated sewage discharges, industrial discharges, urban runoff, and

* chemical spills has generated considerable concern. This has prompted the

scientific and regulatory organizations to reevaluate existing disposal

*methods and options.

"The New York District, Corps of Engineers, now has analyzed more than

* 150 bioassay/bioaccuaulation tests. The analyses indicate that 98 percent of

* the sediments satisfy the ocean dumping criteria and may therefore be ocean

disposed (1).

Of the 6 to 7.5 million cubic meters of material dredged annually from

* the Port of NY/NJ, approximately 95 to 98 percent is suitable for unrestricted

ocean disposal without any adverse environmental impact. Material shown to

have a statistically significant uptake of one or more of the contaminants of

concern (petroleum hydrocarbons, PCB's, Cd. Hg) requires modification to

* unrestricted ocean disposal before the material may be safely disposed at sea.

S."In order to consider ways to dispose of this remaining 2 to 5 percent of

"questionable" material, the New York District has developed a comprehensive

management plan for dredged material disposal to investigate in detail all

options and to Incrementally implement the feasible options (2). An inter- , governmental steering committee composed of Federal and state regulatory

agencies has been established to review all aspects of the management plan.

In addition, inpat from the public is provided through a public involvement

group.

The disposal options have been evaluated using the following parameters:

"engineering, economic, environmental, public health, sociological, and

legal/regulatory. Options were then placed in one of three categories. The

"category, Alternatives Not Currently Reasonable, consists of disposal methods

that merit no further consideration because, under present condit-ons and

using existing technology, they could not be implemented, or because they

offer no clear advantage over more readily available disposal methods. The

* second category, Alternatives Possible in Special Cases, includes disposal

options that would be of use in certain instances depending on degree of

* contamination of the dredged material, physical nature of the material, and

volumes involved.

The third category, Alternatives Possible in Special Cases and Feasible

"for Large Volumes of Material, contains those methods most likely to provide

.. adequate disposal of the quantity and quality of the material dredged in the

New York District.

In this paper we will discuss the following options for the disposal of

""oquestionable" material: use of dredged material as sanitary landfill cover,

upland disposal, and containment areas and islands. These options are not

*. mutually exclusive; any or all of them couli be incorporated into the management program.

177
USE OF DREDGED MATERIAL AS SANITARY LANDFILL COVER

A sanitary landfill is a system for disposing of municipal solid waste by

daily filling of a land area with the waste, compaction of the garbage through

mechanical methods, and covering the material with a layer of soil (usually

0.3 m per day). The layer of soil is emplaced as daily cover, primarily to

prevent disease vectors from being carried from the site by birds and rodents.

* In addition, sanitary landfill cover acts as a fire retardant and an odor

control barrier. Solid waste and cover material are built up in a layer cake

effect (Figure 1). Intermediate cover (usually 0.5 m) is emplaced if, for

• DUMPING

BULLDOZ IM•

S--'--'~~~~---- -- - .,-:-• - VRI

i•_ ~~0.6m FINAL EARTH COVER := •"' 

* I~- Y-'-;DAILY SADADEARTIt COVER

Figure 1. Schematic view of a landfill showing the various operations

and arrangement of "garbage cells" underground

some reason, daily cover has not been placed on the exposed solid waste

surface in the prescribed daily fashion. This may occur at some landfill

- sites because the supply of cover material is sometimes uncertain and not

enough cover material is available to meet daily cover needs. Once the

landfill has been filled to capacity, final cover material (0.6 to 1.5 m of

material) is used to close the landfill. The upper portion of the cover

(usually 0.3 to 0.6 m) must be able to support vegetation because the entire

site is planted with grass and shrubs to improve aesthetics and to control

erosion. Final cover also serves the function of limiting permeability

-5 (10 cm/sec) thereby controlling infiltration, percolation, and gas.

178
,/

Dewatered dredged material can substitute for conventional landfill

cover, which is required by law for daily, intermediate, and final cover

on landfills in the NY/NJ Harbor area. At the present time the average cost

for conventional landfill cover material is $3 to $4 per cubic meter.

However, within the next 1n years. the cost of conventional cover may be as

high as $10.50 per cubic meter according to a study by the New York City

Department of Sanitation (3). Many landfills in the NY/NJ area are scheduled

to close within the next few years and will require final cover material. The

New York District developed a three-phase study of the use of dredged material

as sanitary landfill cover with the Fresh Kills Landfill (NY) and the proposed

DeKorte State Park (NJ) as case examples (Figure 2). In order to establish

a

Sell

- S

Arh mo ANITARY LANDFL

Lee Sa

.. "£ K. N

Kt

Figure 2. Location map of DeKorte Park and Fresh Kills

sanitary landfills

regulatory criteria, the New York District asked the state environmental

agencies for guidance concerning tests and regulations which would be applicable to dredged material to be used as sanitary landfill cover.

1

5'" 179 S..
Phase 1 Report

The Phase I Report (4) indicated that the use of dredged material as

sanitary landfill cover appeared to be feasible. Thirty-three typical dredged

material samples were tested from all of the heavily dredged areas in the

ha-bor including several that were unacceptable for unrestricted ocean disposal (Figure 3). The U. S. Army Corps of Engineers does not have jurisdiction

over upland disposal of dredged material. Upland disposal is regulated by

Xa

A

2

/t"N

Sol

Figure 3. Sample locations of "typical" dredged aterial

for use as sanitary landfill cover

state agencies. They determine the required testing criteria for upland

disposal and use of dredged material as sanitary landtill cover. For the

S~purposes of New York and New Jersey state criteria for testing dredged

material for use as sanitary landfill cover, the Extraction Potential (EP)

: toxicity test was used to approximte the potential of leaching chemical

constituents from dredged material and for comparison purposes with landfill

leachates measured at the Fresh Kills and DeKorte State Park landfills.

The EP toxicity test (40 CFR 261.24) was developed by the U. S. Environmental Protection Agency (EPA) and is mandated under the Resource Conservation

180
Recovery Act (RCRA) for determining the identity and quantity of toxic waste

materials by an acid extraction process. It is important to note that the

intent of the test is to identify toxic waste materials so that they can be

properly monitored and disposed in compliance with EPA regulations.

Hazardous wastes are defined under RCRA by a series of parameters including ignitability, corrosivity, reactivity, and toxicity. Designation as a

toxic waste includes determination of the nature, quantity, anJ concentration

of toxic matdrials; potential for migration; persistence of the toxic constituents; and degree of bioaccumulation exhibited. The EPA has not determined

that the EP toxicity test is an appropriate test for dredged material.

Dredged material does not exhibit tt2 characteristics of toxic waste as defined

by RCRA.

The application of the EP toxicity test was done to meet New York and New

Jersey state criteria for use of dredged material as sanitary landfill cover.

The U. S. Army Corps of Engineers agreed to perform EP toxicity tests on the

33 harbor-wide sediment samples in order to comply with the states' criteria

for use of dredged miterial as sanitary landfill cover.

All of the 33 samples tested for EP toxicity from the NY/NJ Harbor area

were near or below detection limits for the test (Table 1). As discussed

TABLE 1. EP TOXICITY DATA: RANGE OF CONCENTRATIONS OF

CONTAMINANTS IN 33 SEDIMENT SAMPLES (Ref. 4)

Range of 33 values Mean Maximum Allowable

Constituent mg/1 mg/t Concentration, mg/i

Arsenic <0.05 <0.05 5.0

Barium <0.3 <0.3 100.0

Cadmium <0.01-0.07 0.02 1.0

Chromium <0.05 <0.05 5.0

Lead <0.1 <0.1 5.0

Mercury <0.005-0.004 0.007 0.2

Selenium <0.05 <0.05 1.0

Silver <0.02 <0.02 5.0

Endrin <0.01 <0.01 0.02

Lindane <0.01 <0.01 0.1

Methoxychlor <0.1 <0.1 10.0

Toxaphene <0.1 <0.1 0.5

2,4-D <1.0 <1.0 10.0

2,3,5 TP <1.0 <1.0 1.0

PCB's <0.01 <0.01 *

Chlorides 125-489 298.45 *

• No established RCRA limits.

earlier in this paper, only 2 to 5 percent of the annual volume of maintenance

dredged material is unacceptable for unrestricted ocean disposal in the Port

181
of NY/NJ. Although this 2 to 5 percent does contain some contaminants as

would be anticipated in an industrial port area, none of the dredged material

in the NY/NJ Harbor area could be considered to be toxic material or

hazardous waste.

Change in pH over time was measured to monitor the acid-generating potential of the dredged material, it was determined that acid zoxicity would not

occur to vegetative grown in any of the dredged material tested. The PCB

levels were less than the 0.01-mg/L detection limit in all samples.

Approximately 70 percent of the annual volume of fine-grained dredged

material meets the vegetative support requirements and can be used as final

cover. All of the dredged material tested met the criteria for daily and

intermediate cover. This represents 2 million cubic meters of dewatered

dredged material which could meet 40 percent of the annual demand of the 19

NY/NJ landfills (assuming 7.5 million cubic meters dredged material annually).

The New York State chemical testing requirements and functional

requirements for odor, litter, fire, and leachate control were met by all of

the dredged material samples.

Phase II Draft Report

The Phase II Draft Report (5) gives further indication that the use of

dredged material as sanitary landfill cover is technically feasible. The cost

for dewatered dredged material using regional dewatering sites within 10 miles

of the Fresh Kills landfill and DeKorte State Park landfill are considerably

higher than for dewatering onsite at the landfills.

The report investigated various dewatering alternatives: surface

drainage, underdrainage, optimum thin lift, surface trenching, progress±ve

trenching, filling, and crust management. Optimum thin lift is defined as the

amount of dredged material which can be dewatered in a year's time within a

particular climatic regime and was studied by the U. S. Army Corps of

Engineers Waterways Experiment Station (WES) (6). Optimum thin lift

(spreading wet material in a 0.52-m-thick layer) plus surface trenching would

yield approximately 2,140 cu m of dewatered dredged material per hectare per

year. Very thick lifts and extensive crust management would yield 4,586 cu m

per hectare per year. The cost of dewatered dredged material from the

regional dewatering sites studied ranged from $12.95 to $20.60 per cubic meter

(Table 2). A large site near a navigable waterway is the most cost-effective

for a regional dewatering site.

The draft report suggested ways in which the costs could be reduced

including reducing or eliminating land costs and reducing unloading costs by

using two dredges simultaneously. Having the dredgers pay the transport cost

to the dewatering site would reduce costs to the landfill operator.

Comparison of leachate from the landfills with the EP toxicity tests for

the dredged material samples indicates that pollution levels in water leaching

from dredged material would be several orders of magnitude lower than leachate

from the DeKorte State Park and Fresh Kills landfills. PCB retesting (acid

extraction) showed that all of the samples were below the detection limit of

0.01 mg/I (which is 100 times the New York State drinking standard).

182
TABLE 2. ESTIMATED COST PER CUBIC METER OF DEWATERED DREDGED MATERIAL

DELIVERED TO THE LANDFILL STOCKPILE FROM DEWATERING

SITES A, B, C, D

To Fresh Kills Landfill To DeKorte State Park

Site A Site L Site C Site D

Cosc Factor 161 Hectares 32 Hectares 202 Hectares 59 Hectares

Transport to site $3.66 $3.13 $3.66 $3.13

Site development 0 4.05 0 6.27

Site work 0.13 0.52 0.26 0.26

Crust work 0.32 1.04 0.39 0.52

Mobilization/

demobilization 0.39 1.70 0.26 0.91

Unloading 3.92 3.92 1.92 3.92

Subtotal $8.42 $14.36 $8.49 $15.01

Land lease (10 percent of market

value per year) $ 1.83 $ 1.83 $ 7.05 $ 1.83

Subtotal $10.25 $16.19 $15.54 $16.84

Haul to landfill 6.67 6.27 6.54 10.07

Total $16.92 $22.46 $22.08 $26.91

NOTE: The present cost of cover is $3 to $4 per cubic meter.

Phase III

The New York District will continue the feasibility study of the use of

dredged material as sanitary landflil cover. Phase III will consist of:

a. Sampling and chemical testing of dredged material in accordance with

New Jersey Department of Environmental Protection Criteria.

b. A thorough economic analysis of regional dewatering, including all

19 landfills in the NY/NJ Harbor area and any upland sites under

consideration as disposal sites.

c. A feasibility study using a site in New Jersey as a source of dredged

material which is presently in a dewatered state for use as landfill

cover. This site was used for disposal of dredged material from the

Raritan River until 5 years ago. It was extensively studied by WES

as part of the Dredged Material Research Program (DMRP) (7). If

183
permission is granted by the owner, the site could be excavated and

later refilled with dredged material.

d. The feasibility of direct hydraulic or mechanical emplacement of

Gredged material will also be studied at DeKorte St..te Park. A total

of 4.6 million cubic meters of 4 watered material is needed for landfill closure to create the park.

e. A literature search will be performed with regard to the viability of

pathogens in upland disposed and dewatered dredged material.

If the use of dredged material as sanitary landfill cover proves economically feasible, dredged material may be used as a resource material. At present the clean sand dredged from the Port of NY/NJ is used as a resource

material for beach nourishment and for capping. In much the same way, the

finer grained portion of dredged material may become a desirable resource for

use as sanitary landfill cover and become an integral part in the management

of dredged material in the NY/NJ Harbor area.

Regional dewatering sites for use of dredged =sterial as sanitary landfill cover could be established at the upland sites which are also beinZ

studied as part of the Dredged Material Disposal Management Program. Dewatering sites could also be developed at scme of the containment area and island

sites which have been studied by the New York District.

UPLAN2D DISPOSAL

Upland disposal of dredged material is a commonly accepted practice in

the United States and the rest of the world. In the New York District, upland

disposal currently is limited to small Federal, state, and private channels

and slips. Disposal usually takes place at adjacent sites. The present

investigation differs from past practices in that it attempts to locate one or

more sites which could serve as regional upland disposal sites for dredged

material from the Port of NY/NJ.

Dredging and disposal technology and upland disposal site design are both

well established. The primary obstacles to the use of this option for the

Port of NY/NJ are the limited availability and high cost of large tracts of

open land in the greater New York area. The primary task for the New York

District was to locate available land which could be used as environmentally

and economically sound upland disposal sites for dredged material.

A report prepared for the New York District (8) identified and classified

existing undeveloped, vacant land within a 160-km radius of New York Harbor.

This was done utilizing land-use maps generated from LANDSAT satellite imagery

of the region. Three categories of vacant land were identified: crop and

pastureland, wetlands, and barren areas.

In order to develop some means to eliminate unsuitable areas from consideration, we asked the environmental regulatory agencies of the States of

New York and New Jersey to list criteria that would determine the suitability

of upland sites for the disposal of dredged material in their respective

states. Based upon early responses from the.e state agencies it was determined that crop and pastureland and wetlands were very valuable and would not

184
be considered further. This limited further investigations to the 295 barren

areas (land with less than one third vegetative or other cover) which ranged

in size from 4 to 1300 ha.

A preliminary evaluation of these barren areas summarized the most

important factors about each site such as soil type and adjacent land use (9).

The report described cultural features, physical features, and accurate

geographic location, and contained detailed maps and aerial photographs of

each site.

With the input from the state regulatory agencies, the New York District

developed screening criteria for upland disposal siting. Sites were eliminated if they were:

a. Located on predominantly agricultural soil (10, 11, 12, 13).

b. On or adjacent to a major soil source aquifer, in a reservoir

drainage area, or within 1.5 km of any water supply well (14, 15, 16,

17).

c. Within designated significant wildlife areas (18).

d. Located in drainage areas of high quality water such as trout streams

(19, 20).

e. Located on easily soluble bedrock (such as limestone) or porous sand

and gravel (21, 22).

f. Built upon since the earlier screening took place (based on 1980

aerial photographs and site visits).

a. Located in state or Federal parklands or recreation areas (16).

h. Within 150 m of residential areas. Portions of the site beyond the

150-m buffer strip were not eliminated.

i. Adjacent to coastal irosion hazard areas (for New York State).

In addition, the following information about the sites was noted:

I. Flood-prone areas and coastal flood hazard areas (23).

k. Local zoning and site ownership.

1. Distance from the nearest navigable waterway and elevation of the

site (16).

Item number I will help determine the cost of transporting dredged material to the site. It would not be practical to pump dredged material from

several dredging sites directly to a regional disposal site because dredging

needs are widely dispersed throughout the Port of NY/NJ. Since most dredging

in the New York Harbor region is performed by mechanical means (clamshell

dredging), the most likely scenario would be transporting the dredged material

185
by scow to a shore transfer facility near the regional disposal site where the

material can be hydraulically pumped into the disposal site. If the hydraulic

pipeline requires more than one booster pump to deliver the dredged .aterial

from the bhore transfer facility to the disposal site, each additional booster

station would cost over $1 million to build and $67,000 per year to operate.

The next least expensive method to deliver the dredged material to the disposal site would be truck haul an this is approximately three times more expensive than pipeline transport (24). Due to the costs invol'.ed, the New York

District concluded that a site which is more than 8 km from a navigable waterway (the distance which corresponds to a hydraulic pipeline with one booster

pump) should only be corcidered for receiving dredged material which is not

suitable for disposal using less expensive disposal alternatives. Sites which

are less than 8 km from a navigable waterway can be considered for disposal of

any dredged material.

After the screening process took place, the New York District was

considering approximately 56 remaining sites in each state. The state regulatory agencies again reviewed information about these sites, and, as a final

check, the New York District performed site visits. Based upon this information, several more sites were eliminated. At the present time the New York

District is considering 13 sites which might be suitable for development as

regional upland disposal sites for dredged material (Figure 4). They range in

size from 7 ha to 730 ha. Three are located more than 8 km from a shore

facility and will only be considered for dredged material which is not suitable for disposal using less expensive disposal alternatives. A report

describing the project has recently been released to state and local governments, Federal congressmen, and owners of sites and adjacent landowners in the

subject areas who were all asked to supply the New York District with any

pertinent information about the sites. Landowners were asked if they wish to

sell, lease, or allow the use of their property. Public forums were held the

first week of November 1983 in the subject areas.

After local coordination has been accomplished, the New York District

will then perform detailed environmental and economic studies on the remaining

sites. Final siting should be completed by early 1985.

CONTAINMENT AREAS AND ISLANDS

The containment areas and island option consists of the filling of diked

areas with dredged material to form artificial islands or areas. The areas

are attached to land on one or more sides to form peninsulas or to fill in

coves. This is accomplished by disposing of dredged material within the diked

area. At the present time, this option is not considered economically

feasible in the unprotected waters of the open ocean off the coast of New York

and New Jersey (25). Construction of containment areas and islands is considered feasible in protected shallow waters (26).

Containment areas and islands are of particular importance because they

represent one of the new alternatives to ocean disposal which may accommodate

"questionable" dredged material. The engineering and aesign feasibility of

containment facilities (areas and islands) has been well established through

comprehensive studies by WES as part of the DMRP. Containment areas and

islands have been successfully used throughout the United States. For

186
x 837

S421 X

Z X

'Ir.

N16L1

t N37 3 L5

N

Figure 4. Sites proposed for further study in October 1983

example, the Craney Island, Virginia, containment facility has been in

operation for more than 35 years.

This alternative shows potential for the full range of dredged material:

from material that is acceptable for unrestricted ocean disposal to material

which is unacceptable for ocean disposal ("questionable" material).

Uses of Containment Facilities

Containment areas and islands which have been constructed throughout the

Unieed States have been dewatered over a period of 10 to 20 or more years to

form solid land. The land has been used for recreational areas, bird sanctuaries and nesting areas, and light industrial areas, among other usas. However, the facilities could also be used as a materials rehandling center (i.e.

to separate sand for construction purposes from other grain sizes of dredged

material), or for dewatering areas for use of dredged material as sanitary

landfill cover.

Containment areas and islands are constructed in an environmentally sound

manner so that dredged material, including "questionable" dredged material, is

187
isolated from the environment. An impermeable liner (of plastic or clay)

would be emplaced to prevent possible contamination due to leaching, and a

weir system controls the rate and composition of effluent retirning to the

waterway.

Containment facilities are usually divided by several internal dikes to

promote efficient dewatering. They can be divided into cells to separate

acceptable dredged material from "questionable" dredged material. Ideally,

several containment facilities could be located throughout NY/NJ Harbor area.

The availability of containment facilities on several reaches within the NY/NJ

Harbor area would minimize transportation costs because the material would be

dredged from projects in close proximity to each facility. This would eliminate the added transport costs of disposing of dredged material at the "Mud

Dump" site where 90 percent of all NY/NJ dredged material is currently disposed. .n addition, dredging costs may be lowered because hydraulic dredging,

which is more economical for dredging material and emplacing it within a short

distance, could be used in place of clamshell dredging. Clamshell dredging

with subsequent barging of dredged material to a disposal site is more expensive than hydraulic dredging, but allows the material to be transported

greater distances than is possible with hydraulic dredging. Clamshell dredging is the method which is used for most of the volume of maintenance dredging

in the NY/NJ Harbor at the present time.

Preliminary siting for containment areas and islands was done with the

help of the U. S. F~sh and Wildlife Service (27). Their report defined areas

of high biological productivity which were then dropped from further consideration. The report also prioritized areas for further investigation and recommended that siting of a large containment island (greater than 400 ha) be

limited to the Lower Bay of New York Harbor. The Nev York District incorporated the results of the report into their siting criteria and began

secondary siting for containment areas and for wetlands stabilization areas

(disposal of dredged material which is stabilized by planting marsh vegetation

to form wetlands). Siting criteria were developed to narrow down the areas

for fvrther study by the application of appropriate regulatory, economic, and

environmental considerations.

A thorough field invest:gation of the NY/NJ Harbor area was conducted by

the WES and the New York ±istrict. Using the criteria presented in Table 3,

and criteria specific to the viability of wetlands vegetation, nine sites were

identified for wetlands stabilization (28) (Figure 5). The WES report recommended that five sites be used concurrently because they represent a good

geographical spread of locations. These sites were ranked according to relative cost of construction (dike length/volume ratio) and distance of hauling

or pumping from heavily dredged reaches.

After evaluating the criteria (Table 3) the Corps decided that the siting

criteria for containment areas and islands were very similar to that for wetlands stabilization and that the confined sites defined in the WES report

would also be suitable for containment areas.

The costs shown in Table 4 are the minimum costs for zontainment facility

constrioetion and assume availability of suitable onsite material for dike

construction. Actual dike costs and total construction costs of containment

188
o °

I Sligely, Nook. NJ Sb

2 Rw m Say. NJ

3 Caw" Potts. NJ

4 Bowery Bay. NY

5 PF dlwN Say. NY 4&

6 Powell Cove. NY

7 Little may. MY

8 Little Neck Bay. MY

9 Neworf Bay. NJ Qoweee

stolen ilean'd Brooklyn d

Lower ay y a

2 Parties. Say Oe

N

Ka

Figure 5. Wetland stabilization and containment

area sites

areas and islands are likely to be considerably higher than those listed. An

estimate of construction costs for an 80-ha containment site using sand, rock,

and steel dikes with materials brought from off the site is $40 million.

A containment facility designed to hold only "questionable" material may

be suitable for one of the sites such as the Newark Bay site. This would

provide a disposal facility for maintenance and private dredging from this

highly industrialized bay.

Remaining Containment

Facility Sites, NY/NJ Harbor

Se, eral sites were dropped from further consideration due to comments

received from the Steering Committee. The sites which remain to be studied

are: Raritan Bay (Sayreville and South Amboy, N. J.), Bowery Bay (Upper East

River, N. Y.), Flushing Bay-North (Upper East River, N. Y.), and Newark Bay

(Port Newark, N. J.). Their firnal use (wetlands versus containment areas) has

not yet been determined.

189
"TABLE 3. SITING CRITERIA FOR CONTAINMENT AREAS AND4I)

"ISLANDS IN THE NY/NJ HARBOR AREA

Prohibited from areas of high biological productivity

Prohibited from navigation channels

Prohibited froe recreational beaches

Minimum capacity 230,000 cu m

Minimum capacity for large containment island 76,450,000 cu m

Containment araas attached on one or more sides to land

Accept full range of dredged material including "questionable" dredged

material

Prohibited from areas inaccessible to na,,igation

Prohibited from restricted military zones

Prohibited from active fault zones

Avoid anchorage areas

Avoid incompatible uses in the public interest (navigation and port projects)

Avoid major extension and relocation of sewer lines (cost = $6,O00/linear

meter on a major line)

Buy-out of users of the waterway must be cost-effective

Site protected from wave energy:

Minimize fetch (distance over which the wind travels to create waves)

Shoreline configuration should be a cove or meandering shoreline

"Grain size in swash zone between 0.4 and 0.8 mm

Tidal range: 1.8 m maximum

"Wetlands exist nearby (preferred)

Minimize construction cost by comparing diko length to containment volume

ratio for sites (small dike length to volume ratio preferred)

Hauling distance from dredging site should be minimized (should be close to

heavily dredged sites)

Good geographic coverage of harbor area preferred (multiple sites located on

separate reaches preferred)

S..

The New Jersey Department of Environmental Protection (NJDEP) suggested

that the Newark Bay site become a containment area for dredged material W::ich

is not acceptable for unrestricted open water disposal and posstbly' a dewaterIng site for use of dredged material as sanitary landfill cover. The use of

"Bowery Bay and Flushing Bay which flank LaGuardia Airport for wetlands stabilization was objected to due to potential problems with bird populations. None

of the agencies objected to the use of Bowery Bay. The Rarit#i Bay site could

be used for either wetlands stabilization or a containment ar.2 , but would

need to be compatible with development plans for the area.

r

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191
Final Siting

Public forums will be held in the local areas to gain additional public

comments to the sites. The use of the sites for either containment areas or

wetlands stabilization will then be determined.

One year of physical and biological sampling and mo-itoring of the sites

will be performed. This study will include site-specific physical and

engineering properties of the sediment, subsurface geology, hydrology, and

characterization of benthos, fish, and wildlife. The Waterways Experiment

Station will provide site-specific dike and/or containment facility design.

Final siting of containment areas will be coordinated with Federal, state,

and local governments; community boards; and local residents. The New York

District will analyze the final siting data and produce a Po-ition Paper on

the feasibility and acceptability of containment areas and islands.

The Large Containment Islands Concept

The Large Containment Islands concept was studied separately and concurrently with smaller containment areas and islands. Large containment islands

siting studies by the New York District consisted of the feasibility of siting

one or more containment islands, 400 or more hectares in size, in the NY/NJ

Harbor area. Large containment islands are constructed by placing dredged

material in diked areas over a period of time (usually 10 to 20 years),

dewatering the dredged material, and forming solid land which can be used

productively.

As discussed in the section on containment areas and islands above, the

large containment islands concept is restricted to siting in shallow, protected waters. This option was considered to be "possible in special cases,"

but was singled out by an intergovernmental regulatory agency Steering Committee for special consideration because it is one of the few options which

could prove feasible for disposal of "questionable" dredged material (material

which is not suitable for unrestricted ocean disposal). Other potential

advantages of siting large containment islands include disposal of 20 or more

years of maintenance dredged material from the NY/NJ Harbor area and decreased

transport costs from most reaches to a centrally located site within the harbor

area rather than to the "Mud Dump" site for ocean disposal.

The engineering and economic aspects of construction of large containment

islands have been extensively studied by WES in the DMRP together with methods

for confining and dewatering dredged material in an environmentally acceptable

way. The results of the studies have been applied to construction of large

containment facilities by the Corps throughout the United States. Recently,

tha Corps constructed the Hart-Miller Island (Baltimore, Maryland) containment

facility in cooperation with the state. This facility is a multiuse area

which has docking facilities and recreational beaches fringing the dikes and

incorporates two former artificial islands. It is expected to become a

recreational area once the site is filled and the dredged material is

dewatered.

192
Preliminary siting of large containment inlands by the U. S. Fish and

Wildlife Service, using criteria developed by the New York District, limited

further siting to the Lower Bay of New York Harbor (27). The limitation was

done on the basis of size and environmental impact because the Lower Bay is

the only protected shallow-water area in the NY/NJ Harbor area which could

accommodate one or more 400-ha (or larger) islands. In other areas the size

of the island would cause deleterious impacts on water circulation and cause

severe environmental impacts.

A report on large containment islands in Lower Bay, New York Harbor, was

prepared (30). The report reviewed previous large island proposals that had

been sited in the Lower Bay, but had not been built, and discussed the

environmental engineering and economic concerns of siting large containment

islands in the NY/NJ Harbor area. Although the large containment island

concept has many positive attributes, as described above, 3everal limiting

factors led the New York District to conclude that the large containment area

option is not feasible at the present time and should be dropped from further

consideration in the Management Plan (31). The New York District Position

Paper on Large Containment Islands noted that the location and configuration

of a 400-ha or larger island would be restricted to the West Bank of the Lower

Bay. Model studies by WES in conjunction with a siting study for a

containment island which would have enclosed Hoffman and Swinburne I3lands

(artificial islands made partly of dredged material) indicate that a

teardrop-shaped configuration of 690 ha including both islands would cause the

least disturbance to circulation patterns in the Lower 'Ray (32). The National

Park Service objects to present use of these islands as part of a containment

island because they have other plans for the man-made islands as part of

Gateway National Recreation Area. The cost of construction oi a large

containment island per cubic meter of capacity is two to three and a half

times that of ocean disposal. Serious land-use issues, final use, and

ownership of the island(s) would need to be resolved. Moreover, the

ecological value of at least 400 ha of bay bottom which would be irretrievably

lost if a containment island were constructed in that particular location is

at issue (31).

The Position Paper on Large Containment Islands was sent to the Steering

Coumittee and Vice Chairpersons Group of the Public Invclvement Coordination

Group for review. The comments received so far indicate that the U. S. Fish

and Wildlife Service agrees with the New York District's position that the

option be dropped from further consideration until the issue of the value of

the bay bottom can be resolved. The State of New York Coastal Management

Program would like the option to be considered further and suggested that

synoptic fisheries studies be conducted in the Lower Bay in order to determine

whether there are areas of lower productivity which could be acceptable for

large containment areas. Such an assessment is currently under way by the

National Marine Fisheries Service. Additional cements are anticipated from

the other members of the Steering Committee. Once these are received, a

decision on continuance or discontinuance of studying the large containment

island option will be forthcoming.

Sport fishermen's groups have delayed a smaller demonstration project

(filling of a small part of a subaqueous borrow bit in the Lower Bay) through

litigation due to environmental concerns. The project would have covered

193
"• .. -~ - .' . --- .'• " .7 * °''o. - -. "- -.. ',* 7" - -. • ..... . • " .° .• ." =."." . " . .° . . ."° ° ..

19 ha of bay bottom and would have contained only material acceptable for

unrestricted ocean disposal. A large containment island would be used for

disposal of the full range of dredged material, including material which is

unacceptable for unrestricted ocaan disposal and would be more than 20 times

the size of the borrow pit demonstration project. In addition, many areas in

the Lower Bay are known to be highly biologically productive and support a

sizable sports fishing and commercial fishing industry. Siting a large

containment island in an area which is considered to be productive by

fishermen's groups would seem unlikely, judging from previous experience with

the borrow pit project.

Several of the large containment islands which have been previously

proposed for study and/or implementation are shown in Figure 6. Of these, the

site proposed by the NJDEP is in the least desirable location because,

although it is situated near heavily dredged reaches, model studies have shown

that circulation would be greatly disrupted.

0

o94

"soa"

N

41

Figure 6. Locations of previously proposed containment

islands and study areas

194
CONCLUSIONS

The dredged material disposal alternatives discussed in this report

appear to be technically feasible. These three options are potentially

applicable to 2 to 5 percent of the 6 to 7.5 million cubic meters dredged

annually from the Port of New York and New Jersey.

The feasibility studies for the sanitary landfill cover option have

resulted in the development of siting criteria and regulations concerning use

of this option. Dredged material may provide a valuable source of cover for

landfills in the NY/NJ Port area provided that it proves to ba economically

feasible. Upland disposal siting has located 13 potential upland disposal

sites. Some of these could be used as dewatering sites for use of dredged

material as sanitary landfill cove:. Siting of containment areas and islands

is under study in four areas of the port regicn. Containment areas and

islands could be used as dewatering and rehandling sites for use of dredged

material as sanitary landfill cover or developed after being filled as

parklands or industriai areas. The large containment island concept has been

recommended to be dropped from further consideration at the present time by

the New York District due to several factors, especially the difficulty of

locating an environmentally acceptable area and the cost (two to three and a

half times the cost of ocean disposal).

All three disposal options appear to be technically feasible. However,

the major obstacle in implementing any of these options appears to be public

acceptance rather than technical issues.

REFERENCES

1. Suszkowski, D. J., and Mansky, J. M. 1982. "The Disposal of Sediments

Dredged from New York Harbor," Management of Bottom Sediments Cont-Uning

Toxic Substances, Proceedings of the 6th U. S./Japan Meeting, Tokyo,

Japan.

2. U. S. Army Corps of Engineer. 1980. "Dredged Material Disposal Management Program for the Port of New York and New Jersey: Incremental

Implementation Plan," New York District, New York.

3. New York City Department of Sanitation. "Fresh Kills Sanitary Landfill,

Staten Island, New York," Environmental Impact Statement, in preparation

by Parsons, Brinkerhof, Quade and Douglas, Inc.

4. Malcolm Pirnie, Inc. 1983. "Feasibilicy Study for Use of Dredged

Material from New York/New Jersey Harbor as Sanitary Landfill Cover,

Phase 1: Development and Application of Criteria to Sediment Sampling

Results," Report prepared for the New York District, Corps of Engineers.

5. Malcolm Pirnie, Inc. 1983. "Feasibility Study for Use of Dredged

Material from New York/New Jersey Harbor as Sanitary Landfill Cover,

Phase II: Case Studies at Fresh Kills, NY and DeKorte Park, NJ," Report

prepared for the New York District, Corps of Engineers.

195
6. Haliburton, T. A. 1978. "Guidelines for Dewatering/Densifying Confined

Dredged Material," Technical Report DS-78-11, Dredged Material Research

Program, U. S. Army Engineer Waterways Experiment Station, Vicksburg,

Miss.

7. Yu, K. Y., Morrison, R. D., and Mang, J. L. 1978. "Physical and Chemical

Characterization of Dredged Material Sediments and Leachates in Confined

Land Disposal Areas," Technical Report D-78-43, Dredged Material Research

Program, U. S. Army Engineer Waterways Experiment Station, Vicksburg, Miss.

8. Leslie, M., Aurand, D., Schultz, D., ard Holman, R. 1980. "Disrcaal of

Dredged Material Within the New York District: Volume II, Preliminary

Evaluation of Upland Dispcsal," MITRE Technical Report MTR-78-.8, V.2,

Contracted by U. S. Army Corps of Engineers, New York District.

9. Dresdner, A. J., and Cove, C. J. 1982. "Preliminary Evaluation of Upland

Sites for the Disposal of Dredged Material," Contracted by U. S. Army

Corps of Engineers, New York District.

10. New York State Department of Agriculture and Markets. 1981.

"Agricultural District Program Manual - Land Classification System."

11. New York State Agricultural Land Classifiration Computer Printouts

(Supplied by New York State Department of Agriculture and Markets).

12. U. S. Department of Agriculture. County Soil Surveys, New York and

New Jersey.

13. New York Department of Agriculture and Markets. 1981. Agricultural

District Map.

14. New York Department of Health. 1982. "Community Water System Sources."

15. U. S. Geologic Survey. 1982. "Atlas of 11 Selected Aquifers in New

York," USGS Open File Report 82-553.

16. U. S. Geologic Survey, Topographic Maps, 7.5 minute QuadrL'gle Series.

17. U. S. Environmental Protection Agency. 1982. STORET System, Information

Systems Branch, New York Region.

18. New York State Department of Environmental Conservati-n. 1982.

Significant Habitat Overlays.

19. New York Code of Rules and Regulations, Article 2, Part 700 and Title 6,

Chapter X, Sub-Chapter D, Article 10.

20. State of New Jersey, Department of Environmental Protection. 1980.

"Surface Water Quality Standards, Basis and Background. Proposed

Treatment Requirements of Wastewaters Discharged into Surface Waters of

the State," Sub-Chapter 4.

196
21. State of New Jersey, Bureau of Geology and Topography, LORDS System

Geologic Overlays.

22. State of New York. 1977. Department of Environmental Conservation,

State Geologic S'irvey.

23. Federal Emergency Management Agency, Flood Insurance Program, Floodway

Maps and Flood Hazard Boundary Area Maps.

24. Souder, P. S. 1978. "Dredged Material Transport Systems for Inland

Disposal and/or Productive Use Concepts," Dredged Material Research

Program, Technical Report D-78-28, U. S. Army Engineer Waterways

Experiment Station, Vicksburg, Miss.

25. U. S. Army Corps of Engineers, New York District. 1983. "Disposal of

Dredged Material from the Port of New York and New Jersey," Environmental

Impact Statement.

26. Conner, G., Aurand, D., Leslie, M., Slaughter, J., Amr, A., and

Ravenscroft, F. I. 1979. "Disposal of Dredged Material Within The New

York District: Present Practices and Candidate Alternatives, Volume 1,"

MITRE Technical Report MTR 7808, V.1, Contracted by the U. S. Army Corps

of Engineers, New York District.

27. U. S. Fish and Wildlife Service. 1982. "Report on Preliminary Siting of

Containment Areas and Islands," Report prepared for the U. S. Army Corps

of Engineers, New York District.

28. Allen, H. H. 1983. "Siting of Areas for Creation of Wetlands from

Dredged Material in New York Harbor," Report prepared by U. S. Army

Engineer Waterways Experiment Starion for the New York District, Corps of

Engineers.

29. U. S. Army Corps of Engineers, New York District. 1983. "Report on Site

Selection for Dredged Material Disposal in Containment Areas and as

Wetland Stabilization."

30. U. S. Army Corps of Engineers, New York District. 1983. "Position Paper

on Siting Large Containment Islands in the MY/NJ Harbor Area."

31. Bokuniewicz, H., and Summers, R. 1983. "Draft Report on Large

Containment Islands in the Lower Bay," Report prepared by Marine Sciences

Research Center, SUNY, Stony Brook, NY, for the New York District Corps

of Engineers.

32. Howard, Needles, Tammen, and Bergendoff. 1976. "New York Harbor Phase I

Feasibility Study for Dredged Material Disposal," Report to the U. S.

Army Corps of Engineers.

197
, • * &,, •, N..• . "v-..*]• t°7' ,* ". .'.- - - - -• •- .- - . . -.- ° - - - - ... 

REHABILITATION OF ESTUARIES IN TSU-MATSUSAKA HARBOR

S. Hamaguchi

Director, Public Engineering Work Dept.

of Mie Prefectural Government

13 Komeicho, Tsu City, Mie Prefecture, Japan

INTRODUCTION

This paper continues discussion of the pollution control project in TsuMatsusaka Harbor. Diuzussion of the project began at the 6th U.S./Japan

Experts Meeting; at that time dredging had not begun. To improve the harbor's

water quality, it was necessary to remove the polluted sediments from the

Shitomo and Iwata Rivers flowing into the harbor. At present, dredging of the

Shitomo River is complete and dredging of the Iwata River is continuing.

BACKGROUND

Mie Prefecture is situated approximately in the center of Honshu Island

and faces Ise Bay (Figure 1). It has an area of 5,760 km' and a population of

1,720,000. The coast has a total length of 1,080 km with two major harbors,

Yokkaichi and Tsu-Matsusaka, and 17 local ports.

Tsu-Matsusaka Harbor lies in the center of the southern half of the Ise

Bay 'oast. This harbor has a coastal length of 30 km extending from Tsu City

in the north to Matsusaka City in the south and has a harbor area of 61 km2 .

In 1971 the two regions, Tsu and Matsusaka, were consolidated into one

major harbor. As a base of inland marine transport, coastal industries,

Nagoya

Yokkaichi

Tsu Tsu-Matsusaka

Harbor

SHo shu Island Ise Bay

Hie Prefecture The Pacific Ocean

Japan Mie Prefecture

Figure 1. Location of Tsu-Matsusaka Harbor

198
marine recreation, and fishery, the port handled goods in the amount of

1,478,000 tons in 1981.

Ise Bay has surface area of 1,620 km2 and a coastal length of 290 km, It

is larger than Tokyo Bay and Osaka Bay as shown in Figure 2 and has a water

depth of less than 15 m in most parts (50 percent).

Ise Bay Tokyo Bay Osaka Bay

Akashi

Naqoya jTokyo C-Osaka

H anda yw~k ), Yokach &aWaSak2 Sunmoto

Tsu TO Tokoname r /i 

na Toyoha '1azu

Matsuza a Yokosuka Wakayama

/Kam 1 ima

Castal 290 km 154 km 160 km

Length .......

Water Area 2,130 km2 1,160 km2 1,400 km2

Water Depth

- Ism 1,000 km2 560 km2 390 km2

- lO M 620 km2 360 km2 140 km2

- 5m 290 km2 180 km' 35 km2

Figure 2. Comparison of Japan's three largest bays

Since 1960, the rapid progress of the Japanese economy has caused

environmental problems notwithstanding the elevated living conditions. In

Yokkaichi, asthmatic patients took legal action concerning the serious air

pollution problems.

For water pollution, the prefecture government is making an effort to

reduce the quantities of pollutants flowing into the Bay. In Tsu-Matsusaka

Harbor, the problem of cleaning up the Shitomo and Iwata Rivers has been

investigated.

SEDIMENT

Survey

Water pollution of Ise Bay deteriorates the shoreline environment. The

accumulated sediment and red tides in the bay cause foul odors. The red tide

causes decreases in marine products and a decline in tourism.

199
To study this problem, a sediment survey was conducted within the Shitomo

and Iwata Rivers in 1978 and 1979. These tuo rivers flow into the harbor and

are believed to be the source of the sediments which cause the foul odor.

The sediments of the Shitomo and lwata Rivers have a black color and a

strong hydrcgen sulfide odor. Water content of tha Shitomo River is 194 percent, liquid limit is 121 percent, and plastic limit is 43.6 percent.

The grain size composition of sediment in the Shitomo River is 3.8 percent sand, 71.2 percent silt, and 25 percent clay.

The pollution indexes COD., ignition loss (I.L.), aad sulfide content

are shown in Figure 3 according to sediment depth.

CODMN II.L., Sulfide,

10 20 30 40 so 10 2C 30 1 2 3 4 S 6

0 20 2.

2 12

5 3 3 3

SS rFigure 3. Pollutant concentrations in sediment; Curve No. 1 represents upstream and Curve No. 2 represents downstream

The sediment at Iwata River has a thinner thickness (3 m) than that of

Shitomo River (4 m). The silty and clayish portion of the sediment is more

than 80 percent, water content is less than 200 percent, and ignition loss is

less than 10 percent. However, t~oncentration of COD is comparatively high.

Removal Cr!teria

There are no official guidelines in Japan establishing polluted sediment

removal criteria. For this study we used the following criteria for removal:

CODMN = 10 mg/g, ignition loss - 5 percent, and sulfide content - 1 mg/g. The

limit concentration for sulfide was considered an important factor in eliminating foul odors.

Thickness to be Dredged

By considering the vertical distributions of COD., ignition loss, and

sulfide, the sediment thickness to be dredged was determined. Of these three

indexes, the ltmit/concentration of sulfide (1 mg/g) was the most important.

The thicknesses of sediment which indicate sulfide concentrations of more than

200
1 mg/g are shown in Figure 4. Figure 5 shows the vertical distribution of the

sulfide.

Measured Stations

Upstream StF stD Downstream StB

StlO StH St9 StG StX StE Sts StC St7 StA St6

U

1-.0 *• a. -2.0 3Right Bank

0 -3.C •

S-4.0

Q

I -5.0

-6.0 Left Bank "

Figure 4. Dredged depth in Shitomo River

4 Sulfide,mg/g 4 Sulfide,mg/g

0 123 4 567 0 1234 5 67

Min. MaAvg.x.

Upstream , b e ,

0 dged2 To be '0 o .J"5

Sdredged W "

' 2.0,* "a0

/ , " 2.5

Downstream 4 * /

Iwata river

Shittomo river

Figure 5. Vertical distribution of sulfide

From this, the following dredging depths were selected for the Shitomo

River:

a. Downstream - 4.5 m

b. Middlestream - 3.5 m

c. Upstream - 2.5 m

201
For the Iwata River, the following depths were selected:

a. Outside harbor - 2.5 m

b. Inside harbor - 3.5 m

OUTLINE OF DREDGING WORK

"Dredging

Figure 6 shows the dredged area in the Shitomo River and the disposal

site located near the river entrance.

:'i L

bII

Dredged Area

- Disposal

"Figure 6. Dredged area in Shitomo River

The total amount of dredged material was 105,000 ms3 in 1980, 166,900 m3

in 19IM, and 50,300 m3 in 1982--a total of 322,200 Ms3 .

Since the original dredge that operated at Shitomo River in 1980 had a

diesel engine and was noisy, the nearby residents objected. Therefore, it was

replaced by a dredge with an electric engine E-1000 PS in 1982.

"Suction was used as a rigger cutter due to the hardness of the lower

layers. Swing speed was 9 to 10 m/min; swing range was 45 to 50 m; and flow

velocity of dredged material in the pipe was 4 to 5 m/sec. Downtime due to

obstacles such as chips, wires, vinyl products, and screens was about

2 hr/day.

202
In order to lessen tutbidity caused by dredging, especially in low tides,

turbidity prevention sheets (called "silt protectors" in Japan and "silt cur-

"" tains" in the United States) were placed above and below the dredged area.

The inspection points are shown in Figure 7. The inspection standards

are shown in Table 1.

0Water quality

Figure 7. Inspection points (Nos. 1 and 2 are the basic inspection

points. No. 3 is the auxiliary point.)

TABLE 1. INSPECTION STANDARDS

"Unit Standard Monitoring Monitoring Point

ph 7.8 - 8.3 Two times/day Basic two points

COD ppm Less than 5 Two times/day Basic two points

DO ppm Less than 5 Two times/day Basic two points

SS ppm Less than 50 One time/week Basic two points

Turbidity Degree* Less than 50 Two times/day Basic two points

Turbidity Degree Less than 50 Four times/day Auxiliary one point

* One degree of turbidity indicates that there is 1 mg-kaoline in a liter

of pure water (i.e., 1 degree - I ppm).

Compared to these standards, the operation results were as follows

(Figure 8 shows the measured values of these indexes):

203
No. 1

Nn '

"- 30 .

20

olO

210.

----.-----------...... ........ ... - .....

• • 2 0 - - - - - - - - --- - - .................. . . °°°........ ....... ... ° ° ° ° ° ° .............. ° ..... • .............. . ..... .° • ° °

k.'4

10 

A

Date27/ 1/ 10/ 21/ 28T

May June June June June :.:'2

Figure 8. Measured values

a. 2H. The measured values during the work were mostly 7 to 8 and

therefore met the standard.

b. COD. The measured values of COD remained mostly within 5 to 10 ppm.

c. Suspended solids (SS). The concentrations of suspended solids were

less than 50 ppm. Most concentrations were less than 20 ppm.

d. Turbidity. Turbidity did not create a problem. The measured values

were less than 50 ppm (SS).

The dredging operation was judged acceptable since the inspected results

met the standards in Table 1 except for COD, which remained mostly within 5 to

10 ppm.

Disposal

The dredged material was conveyed hydraulically to the disposal site near

the river entrance (Figure 9). At the disposal site, deodorization and spill

water treatment plants were constructed as mentioned in subsequent paragraphs.

The conveying and disposing of dredged material went smoothly since the

disposal site was located near the dredge.

20,-
A; V .-. -% U.%n. -k 

°a

1Ipo a sal ;Di~sposal I

D~.IsoosaI Disposal *Lime Mzilk Plant

S: FeCt 3 Plant h, 6pill Water Treatment Pond Piping

Shitomo River Dredqe I•

Figure 9. Disposal site

Deodorization and Spill Water Treatment

Deodorization Plant

The generation of odors from sediment is a phenomenon created when gases

separate from the sediment via bacterial action such as sulphate-reducing

bacteria in anoxic conditions.

Organic sulphur compounds are produced when the oxidation and reduction

* potential (ORP) of sediment is 0 to 200 mV. Therefore, to prevent odors, the

absolute value of ORP must be lowered, i.e.* decrease the anaerobic conditions. To do this, iron chloride was used because its effectiveness has been

verified by laboratory tests. It is also known that the addition of slaked

lime to iron chlorides makes the deodorizing action more effective since

* sulphur compounds react chemically with iron chloride and reduce free sulfide,

* the odor-causing substance.

Iron chloride (33 percent solution) was injected into the conveying pipe

at the point of discharge and at a point 50 m from the discharge point. , Slaked lime milk was added to neutralize the liquid containing iron chloride.

-. Iron chloride and lime milk plants are shown in Figures 10 and 11.

205

I"
4370 355 3550 1670

F 13140

Inlet I

(20 a!) (20 m3) (20 M3)

Figure 10. Iron chloride tanks (units in millimeters)

Bag F lterBucket Elevator

SS

BalchhJ

- ier Ln

yOzAg con 4

L44 2"615W4 0iýf 0jr

r Figure 11. Lime milk mixing plant (units in millinseters)

206
The annexed quantities of deodorants were as follows:

a. Dredged material: 3,000 m'/hr, average

b. Iron chloride: 1,000 ppm, average

c. Slaked lime: 250 ppm, average

The standards for odor inspection are shown below:

Monitoring Times

Measure Pt. Standard During Operation

H S Leeward of 0.02 ppm 10

2 outlet

Methylmelcaptan Leeward of 0.002 ppm 3

outlet

The measured values were all under the detection limit of 0.0005 volume

per volume (v/v).

SpiUl Water Treatment

Since the hydraulically dredged material contains large quantities of

water when it is disposed in ponds, spill water has to flow over into the sea.

If the spill water is untreated, secondary pollution of adjacent seawater

results. Therefore, it is necessary to treat spill water. In this case,

treatment consisted of a sedimentation pond system with the coagulating agent

PAC. A flowchart of the treatment system is shown in Figure 12.

Anionic flocculants were first injected into the slurry pipe before the

inlet of the primary settling pond. To enhance secondary sedimencation of

suspended solids, small quantities of flocculants were added a second time.

Coagulant PAC was added at the inlet of the secondary pond to promote coagulation by polymerization.

The added quantities of coagulants were as follows:

a. Polymer, 5-10 ppm, primary

b. Polymer, 1-3 ppm, secondary

c. PAC, 50-100 ppm, secondary

Inspection of Water Quality

For the monitoring and inspection program, the predredging water quality

was measured (Table 2).

207

0
i

/

settling Pod

Figur Flosh Boardt

Fl-AjsteawtrRvrae ioo

L, Fls or settl ing pond

SBuffle PlateI

.7 - Parameterhargeeank RneMa ag

pH 8.1 7.2 - 8.2 8.2 7.2 - 8.7

COD, 

SS, mg/ 

mg/t 4.7 2.9 - 7.1 5.2 3.3 - 10.0 i 18.9 5.0 - 65.0 26.0 5.0 - 140 Turbidity, degr. 8.0 3.0 - 17.0 10.6 3.9 - 12.0 SHydrogen sulfide, v/v ppm -- . 0.0022 ND -, 0.025

Methylmelcaptan, v/v ppm ........

* Considering these predredging data and general environmental standards, the

inspection criteria selected are presented in Table 3:

q

I. 208
TABLE 3. INSPECT7ON CRITERIA

pH At discharge tank 5.8-8.6 Two times/day

COD At discharge tank Less than 25 ppm Two times/day

SS At discharge tank Less than 50 ppm Two times/day

Turbidity At discharge tank Less than 50 ppm Two times/day

(SS)

Compared to these criteria the operation results were as follows:

a. pH. The measured values during dredging were mostly 7 to 8 ppm and

therefore passed the criteria.

b. COD. The measured values of COD luring dredging remained within the

criteria of less than 25 ppm.

c. SS. The concentrations of suspended solids were less than 50 ppm;

most were less than 20 ppm.

d. Turbidity. There was also no problem with turbidity since the

measured values were less than 50 ppm (SS).

CONCLUSIONS

After completion of the dredging work in Shitomo River, the foul odors

disappeared completely. There were no more complaints concerning the odor

from residents. It was also noted that water birds, fish, and shellfish

increased. It appears there are benefits from dredging.

For any pollution control project it is most important to conduct the

work safely apd smoothly without complaints from local residents. From this

point of view, ou, work achieved its goal. However, work still remains to

determine to what degree the river estuaries of Tsu-Matsusaka Harbor have been

rehabilitated.

209
SUBSURFACE INVESTIGATION FOR DREDGINr PROJECTS

R. F. Brissette

Canonie Engineers

Chesterton, Ind. 46304

ABSTRACT

Dredging and tunnel projects have achieved considerable notoriety within the geotechnical community.

In reviewing the history of many of these projects, it

becomes apparent that the reputation arises not from a

failure to adopt so-called "state-of-the-art" technology, but rather a failure to orgarize investigations

to address anticipated problems and to understand the

significance of the data acquired. Ev,,n when these

two elements are present, projects flounder when those

charged with executing the work do not have a clear

grasp of the engineering properties of the materials

they are likely to encounter. As dredging techniques

are more frequently being used to correct environmental

problems, the techniques of investigation and data

management will assume greater importance. The

problems of establishing the types of data to be

acquired, the extent of the data, and how it is to be

used are still with us. Failure to address these

problems rigorously results in excessive costs,

unsatisfactory project results, and, in some cases,

abandonment of projects altogether. This paper relies

upon some old and simple concepts of experimental

statistics to assist in quantifying the reliabil.ty of

subsurface data. Only rarely is this technique used

in practice and yet it is a powerful tool when it is

combined with experience.

INTRODUCTION

Dredging projects are usually characterized by the need to move very

large volumes, often over substantial distances. They include two particular

characteristics that contain the seeds of financial loss. The movement of

material is dependent upon the performance of a single machine And the entire

operation is conducted at sea. These must be key points to an investigator.

Changes in equipment, procedures, and schedules that can be reasonably accommodated on land are not so easily done at sea. For these reasons, the degree

of accuracy required !a subsurface investigation for dredging projects exceeds

most land-based proitcts. Rarely in their careers will geotechnical engineers

be asked to define subsurface conditions over such vast areas, in such detail,

210
and in such a hostile environment. The enterprise demands a sense of humility

because small errors are multiplied by large volumes and large fixed costs.

It is likely that in the foreseeable future a substantial number of large

dredging projects will be channel and harbor deepening projects to accommodate

the ever increasing size of vesseld. Some will be undertaken simply to remove

pollutpd sediments that have accumuleted over many years. In either case, the

nature of the work will often require relatively shallow cuts over broad areas

in existing facilities where environmental and social considerations immediately become important. Particular techniques that may have been acceptable

20 years ago are no longer acceptable. Investigations m-sst be conducted with

that understanding. The requirements of environmental permits alone put

severe constraints on altering techniques once the work is under way, even

when that is possible organizationally and mechanically. These matters must

be understood if a coherent and useful investigation is to be made.

STEPS OF INVESTIGATION

The purpose of a subsurface investigation, in its broadest sense, is to

define the nature of the materials likely to be encountered. The last part of

that sentence has becom- a classic in contract law in the United States. It

has been the basis for a great number of lawsuits, partly because we have

failed to bring accuracy to our work. The purpose of a subsurface investigation is to adequately describe the nature, engineering properties, and variability of the materials likely to be encountered. While the issue of variability is generally recognized, it is usually addressed by incorporating disclaimers into the project documents. When geotechnical engineers disclaim

responsibility for their work, that responsibility is thrust elsewhere. It is

almost inevitable that the responsibility placed elsewhere is less easily met.

These points are made because in most countries, in one form or another, the

practitioner of geotechnical engineering conducts his technical business in a

framework of economic and legal responsibilities.

Figure I has been prepared to outline the principal elementl of a subsurface investigation. Figure 1 does not address projects that are designed

principally as environmental efforts. That is a separate subject requiring

its own format. However, devaloping the parameters will be similar. The

steps are perhaps deceptively simple. However, when one or more of these

steps is overlooked, there is invariably some missing piece of information

that proves crucial to the project. It is useful to describe, at least

briefly, the nature of these steps.

Literature Research

This must be the first step in the investigation. While the information

tends to be global in nature, it will normally at least answer the question of

whether the work is in rock or unconsolidated deposits. Most often it will

provide considerable detail on local deposits and will certainly provide an

early basis for planning the rest of the investigation. The geology of the

area and of the site specifically will provide a knowledge of the geologic

development of the area and hence, to some extent, the variability. As a

practical matter, it will provide enough data so that preliminary studies of

the layout, scheduling, and economics can begin. Most western countries

211
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7 0 

Z,

44 **

2 4. I

0 ad

IL U

hi 0

-4 it4. 0

4I4 LL 0 0

o3. 0 0

9L ~

0- 40 4

2.. 

.40-1

0 '4.4.

4 -

5. j i 0&

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z .

a. 060 4i IL s

U0 42 0 j

04 W

t 0 iJ~ 

hi~ 5 45. -212
maintain excellent libraries of geological information that are available

through universities and government agencies.

The cost of marine investigation is high relative Io other types of projects. The high cost is influenced by the equipment tha: must be mobilized and

the impact of weather. A thorough study of available weather data should be

made so that correct equipment selections are made and the matter of

scheduling can be addressed. That information is easily accessible but frequently overlooked in planning the field portion of the investigation. Information acquired through literature is the least expensive of the information

that is required for the project.

Existing Records

The records of previous studies and construction are an essential source

of information. Where they exist, they will narrow the types of materials

likely to be found, isolate problems peculiar to the site, and help define the

variability of materials. In unconsolidated deposits particularly, dredge

production records can provide critical information on changes in subsurface

conditions not otherwise apparent. It is often possible to establish the

parameters that are likely to be most critical to progress by analyzing previous records. It Lu also in details of previous construction records that

the broad limits of variability are lik.ly to be established.

Investigation Plan

Figure 1 has been prepared to show the stages of investigatiou with

particular emphasis on the parameters that must be established for various

subsurface conditions. It im impractical and probably unnecessary to pursue

each branch of the figure. The essential point is that each element in the

figure must be ixamined and executed or deleted only ou the basis of a

rational analysis of the project requirements.

Let us assume that the literature research shows clearly that a hypothetical channel and harbor deepening project indicates that the excavation will

be in rock with perhaps negligible overburden resulting from shoaling. The

next phase of the investigation is to establish the locations of borings,

their depth, and total number. As a part of this process, it is likely to be

useful to conduct geophysical testing because it is impractical to attempt to

describe the site with any degree of accuracy using soil borings alone.

Channels are ordinarily measured in miles and harbors in millions of square

yards. The task of defining the materials below the sea in these areas is

formidable.

The principal tool today, and likely to remain so for some time, is the

boring. This device gives us a physical sample from which we determine most

of our parameters. From these borings, an experienced engineer can derive

enormous insight into the character of the project by simply examining the

material. For purposes of illustration, emphasis is placed on some rational

method of selecting borings, but the process is equally important in selecting

samples. It is at this stage of the project that sampling requirements must

be defined with respect to the needs of the project.

213
In trying to establish a useful plan of borings, it is wise to divide the

project into several elements. This can be done on a purely geometric basis

or, preferably, where the data exist, into elements characterizing different

known subsurface conditions or different physical properties of the project.

Most of the data should have been gathered in the literature research and the

review of previous construction records. Figure 2 illustrates this point.

In the example, there is a distinct channel project that crosses a physical boundary. Section 1 is excava ion in materials that have not been previously dredged and so no physical data from previous construction are

available--"uew work" in the complete sense. It is the most seaward element

and so the work is most influenced by sea conditions. It is likely to be the

deepest work because in this zone vessels require not only the normal keel

clearance acceptable in the harbor, but sufficient keel clearance to accommodate ocean swells. It is reasoaable, therefore, to isolate this element

because the investigation here is more critical to the orderly progress of the

construction than it might be in the harbor where there is greater latitude to

acco-mmodate unanticipated conditions. This element is about 2500 ft long and

500 ft wide.

It has been shown (i) that a systematic sampling pattern is more

efficient than a random scattering of samples. Fcr this reason, if there is

no reason to the contrary, a pattern of borings spaced along the toe of the

cut at approximately 500-ft intervals is likely to produce a reliable sampling

of the section. Obviously that is not a "rule" in any sense. It is a

rational estimate of what is required if the data generated produce a coherent

pattern. While we understand the desirability of knowing investigation costs

before the project begins, that cannot be the overriding consideration if the

total cost cf the project is to be estimated with confidence.

The next point is embarrassing to make and it would not be made except

that it has been violatcd so many times. When drilling rigs are mobilized for

sea duty, they should be staffed and supported by the most experienced engineers. They must be capable of assimilating, reducing, and analyzing data as

it is recovered. Perhaps more often than not, the initial boring plan will

disclose differences that are unresolved with the existing data. Dredging

projects extend over such large areas that it is likely some significant differences will appear. When that occurs, borings are drilled between these

that show significant differences In subsurface conditions. That process is

continued until the conditions revealed by intermediate borings are those

anticipated from previous bor'ngs and samples. The technique requires fewer

borings than one would be inclined to assume. The cost of that approach is

correctly weighed against the risk of having one large, expensive machine

encounter conditions for which it is not well suited. In dredging, the costs

associated with mobilization alone at' enormous and lost tioe is often counted

in seasons, not days. So while we have not agreed precisely on the number of

borings and their locations, we have agreed on how this matter will be

determined.

The second problem is to defire the depth of borings. Deepening a

channel in rock (coral and cemented sands and gravels are included in this

category) provides some interesting insights into an otherwise simple problem.

Both hydraulic and mechanical dredges lose efficiency in shallow cuts. For

214
00

0

-H

44

14

C4

4.)

40 0

w ow

cc

2154
this reasor alone, one ought to be cautious in approaching a deepening

project. Incredibly, subsurface investigations often reach just to grade or

only slightly below. In the United States, the Corps of Engineers normally

provides for some depth below required grade (called the overdepth) in which

the contractor is payed for material removed although he is not required to

remove it. That is a useful cor.cession to reality because the heavy equipment

in rolling seas cannot cut with the same precision as a scraper on land. So,

to begin, the borings ought to exLend at least to the overdepth. That, however, is still inadequate, particularly if a decision is to be made regarding

blasting. If, for example, there is less than 2 ft to be removed to grade,

the analysis of blasting requirements will depend upon a knowledge of the

material for a depth of 5 to 10 ft below that depth.

Even where blasting is not an issue, some means must be found to remove

the rock efficiently and rarely can that be determined only from the nature of

the rock above grade. So, at least in the instance where rock or rocklike

materials a'e encountered, the depth of the boring should be at least 5 to

10 ft below required grade.

There is a final comment that is appropriate to this issue. We are

inclined to view the costs of borings in terms of cost/foot. That is sometimes misleading because at sea that cost is so heavily influenced by

mobilization, moving between borings, and lost time due to weather conditions.

Once a drill is positioned over a boring and drilling, the cost of deepening a

hole by a foot or two, or increasing the number of samples, is relatively

inexpensive. According, planning an investigation based on minimum lengths of

borings does little to reduce costs yet incurs substantial risk.

Section 2 in Figure 2 is the portion of the entrance channel that has

been dredged previously. There should be a wealth of knowledge preserved in

various archives. A study of these records is essential in planning the

investigation for this section. Rather than basing the number and locations

of borings on a fixed grid system, it should be possible to select locations

based on some degree of variability that is already known. That condition

should be accounted for in the beginning. Once those borings have been

located, the remaining borings are located on the basis of completing subsurface profiles. That is, additional borings are then located so completed

profiles can be constructed by exploring conditions in specific areas of

interest.

The interior harbor (turning basin and berths, Sections 3-7) will demand

the same process of investigative planning as described above, but with additional considerations. Now some consideration must be given to existing

facilities. Existing buildings, sheet pile walls, unloading structures, and

similar construction already in place require particular attention. The mere

presence of existing facilities implies that previous investigations have been

made and will be useful. The investigation should address two principal

issues. The first is that of stability of structures following the planned

improvements. At the very least, it is likely that a deepening project will

reduce support for some structures. The investigation must provide the geotechnical parameters that will allow an analysis of stability of structures

following completion of the project. This should include sufficient data so

that recommendations for corrections to existing structures can be made if

216
*% that is indicated. The type of structure and potential difficulty will dictate

"the number of locations of the borings, their depths, and the type of samples

Si required.

The second principal issue c3ncer~s the effects on harbor facilities during construction. Vibrations, noise, and other environmental considerations

"'" are essential. Blasting, for example, while practical in many cases, may not

"be permissible in some areas whereas there is no problem with the method in

. other areas. W.here the work requires dredging near residential areas it 's

"-* important to have a clear understanding of the types of materials to be

dredged and formulate plans for excavating these areas. What kind of excavation is suitable? What are the noise and vibration characteristics? Should

there be limitations on the length of the working day? These are all

questions that are, at least in part, related to the nature of the materials

being dredged. In these areas, the investigction can be useful in providing

"" data from which estimates of turbidity can be made.

There is no simple rule to offer as a guide for determining the details

*• of the physical investigation within the harbor, or, for that matter, any

portion of a large dredging project. That is not to say, however, that the

investigation must be planned in a vacuum. Outlined above and in Figure I are

* the steps of the investigation and the matters that must be addressed by the

investigation. The layout and depth of borings have been discussed briefly

* •only to illustrate a process.

"It is in these stages of the investigation that the number and types of

samples must be determined, at least approximately. That is an important task

and one that should be pursued on a rational basis. Statistical concepts that

are useful in establishing a basis for selecting sample numbers are discussed

in a subsequent section.

There is a natural division between the Investigation Plan and the subsequent elements in Figure 1. The previous elements, while requiring technical

expertise and experience, are principally organizational and administrative

tasks. Those that follow are matters of execution and analysis. These are

presented not so much for the purpose of discussion, but to complete Figure I

and to illustrate the usefulness of defining the problem clearly. Having

established a framework for investigation, it is appropriate to abandon the

* general discussion and concentrate on the treatment of data acquired in the

next two phases, Field Exploration and Laboratory Analysis.

Geotechnical engineers in particular, and engineers in general, tend to

*• excuse a lack of reliable subsurface information as resulting from two characteristics they allege are beyond their control:

a. Lack of sufficient funds.

b. The inherent variability of subsurface conditions.

The first lament is a universal one. There are never sufficient funds to accomplish all the goals. Its solution lies in the matter of establishing

priorities, understanding clearly what is needed, and then making persuasive

argument.

217
The second lament is a bit more subtle. Perhaps a good analogy to

". examine is that of the ordinary picture puzzle. The manufacturer will adver-

"tise a 5000-piece puzzle with no two pieces alike. But the pieces form a

single picture. As in the case of most analogies, that is too simple but it

gives perspective to the problem. In this instance, the pieces must be

* located and, more importantly, it must be decided when enough pieces have been

gathered to construct a correct picture. The problem is to quantify the

variability and reach a satisfactory "confidence level" that provides

assurance that the correct picture has been assembled. In that regard, a

statistical analysis is useful, but it is one that is rarely used. This

technique is particularly valuable in its application to dredging projects

because such large areas are being defined under such difficult conditions.

It is important to know when adequate data have been gathered to properly

*. define a site to avoid squandering budgets on repetitive but unnecessary data.

Returning to the example that the project requires dredging in rock, for the

purpose of illustration, the unconfined compressive strength of the rock has

been selected as a key parameter that must be defined with some reliability.

The exercise, however, is applicable to any of several characteristics, among

them the Rock Quality Designation, another property of rock that is essential

to estimate excavation characteristics. The technique can be applied to any

"randomly measured characteristic.

A relatively simple probabilistic evaluation, this parameter can be used

to estimate the maximum standard deviation of the population at various con-

* fidence levels. That is a method of quantifying the risk that material may be

outside the limits of the equipment. It is also possible to estimate the percentage of the population that will lie within certain minimum and maximum

values, a process that is useful in making equipment selection.

Laboratory Analysis

Acquiring rock cores at sea is difficult and costly. Nevertheless, the

* Rock Quality Designation, Seismic Velocity, and Unconfined Compressive

Strength are the essential parameters needed to plan the project. The

Unconfined Compressive Strength Qu is used as an example in analyzing data

*- because it represents the data acquired from an actual dredging project.

In this case, the subsurface investigation included the results of two

unconfined compressive tests of the rock to be dredged. The significance of

"those tests will be examined later. What is important is tlat the project

encountered extreme difficulty encountering rock that could not be dredged by

"* the equipment as it was mobilized. As a result, an extensive testing program

was undertaken that produced a total of 99 tests.

Since the data exist, by generating random numbers from I through 99 to

represent each test, it is possible to study the data and quantify the results

ae they might have been generated in the course of the investigation. The

* tests represented values of Q from 360 psi to 12,000 psi, a formidable

u

, range. For purposes of illustration, only a portion of the total number of

S . tests is necessary. Table 1 represents the results of tests represented by

"the first 12 random numbers.

218
TABLE 1. RANDOM NUMBER TESTS

Corresponding Unconfined

Random Compressive Strength

Number psi

54 4894

69 1886

79 1521

37 3587

85 4074

75 2761

35 5778

49 6313

76 1414

46 5854

40 3199

22 1789

When it is intended to measure some characteristic (such as the unconfined compressive strength) of a large population (the rock deposit to be

. dredged), it is neither practical nor necessary to test the entire population.

*. Instead, some portion of the total population can be sampled in a random

manner and inferences can be drawn about the population based on the results of

"* the limited sample. This approach has been found to be very effective in predicting the characteristics and behavior of materials in geotechnical applications. The number of samples tested establishes the confidence levels

(probability) of inferences made about the population. The goal of probabilistic evaluation in the context of this discussion is to quantify the confidence levels that the mean and standard deviation of the population characteristics being measured will fall within. It can also be used to establish 3 the confidence levels for certain critical values. Stated in a simpler way,

the mean and variability of a sample are used to predict the mean and

variability of the population. It is important to remember that a sample in

this discussion refers to a group of tests. A group of tests is a sample of

the population.

There is substantial evidence that many soil and rock characteristics

conform to a standard-normal distribution. The normality of such geotechnical

distributions can generally be anticipated by the Central Limit Theorem and

the fact that these characteristics develop in the population as the result of

many random and unrelated influences. Some degree of skewness should be

anticipated in the distribution of unconfined compression strength since this

Scharacteristic is censored at a strength of zero, as are many characteristics

of interest to geotechnical engineers. That is, while no data can be plotted

below zero, there is theoretically no limit to values greater than zero.

Accordingly, the population is said to be censored, capable of producing a

right tail but not a left. It is, however, reasonable to assume a normal

distribution for the unconfined strength of the population. Figure 3 is a

histogram of all values of Qu (N = 99). An analysis of the 99 tests does in

219
TOTAL NO. OF TESTS=99

MEANz 3589 PSI

STANDARD DEVIATIONZ 2019 PSI

15- COEFFICIENT OF VARIATION :56.3%

'LA

W0 

z El INITIAL DATA

"[iSUBSEQUENT DATA

0

IL

0

5-

0

U. D 0 I .. M.i.i :.il........................

0 2000 4000 6000 8000 10,000 12,000 14,000

UNCONFINED COMPRESSIVE STRENGTH, PSI

Figure 3. Histogram of all values of Qu

fact produce values of skewness and kurtosis that compare favorably with the

theoretical values of 0.0 and 3.0, respectively. Accordingly, it can be

analyzed using the technique described below.

Based on standard statistical techniques for small samples, it is possible to determine the probabilities that the mean strength of the population

will not exceed certain values critical in determining equipment requirements

and production rates. While it is possible to calculate the probabilities of

the mean strength falling below a specific value, in this instance we are

interested in determining what the maximum average strength might be and how

sure are we of that result.

The upper limits of the mean strength of all the rock (the population)

can be estimated for various probabilities using the single-sided Student's t

Statistic for small sample evaluation. This has the form:

Qu(P) <. + t~pv

where

x " sample mean

t p Student's t distribution for a probability of P

(p,v)

v " degree of freedom (n-1)

220
s - standard deviation of the sample

n - number of tests

The equation is read as:

There is a probability of P that the mean strength of the population

will be equal to or less than the sample mean plus the standard deviation of

the sample mean times the Student's t distribution for that probability.

While that description of the equation is correct, it is not illuminating

to the practicing engineer. The relationship can be phrased in a more useful

way.

The probability is P that the mean strength of all the rock will not

exceed a specific value of Qu "

Because of the cost associated with acquiring and testing rock samples,

it is important to know how many tests are required to produce a useful

result. The result must be useful in that it must clearly convey the range of

values within which the rock strength will occur. That point is clearly

illustrated by examining the data set in Table I.

If it is assumed that the investigation was limited to only two tests,

the maximum value of the anticipated population mean for a 95 percent confidence level can be calculated from the following expression:

For test numbers 54 and 69

- 3390 psi and s - 2127 psi

Qu(P - 0.95) 5 3390 + tp(2127)

where

n - total number of tests in the sample

tp - Student's t Statistic selected for a probability of 0.95 and the

degree of freedom, n-i; tp - 6.31375

Q - 3390 + (6.32375 x 2127)

Qu - 12,886

The result can be stated as follows:

There is a 95 percent probability that the mean strength of the population will not exceed 12,886 psi.

This estimate is based on only two samples and intuitively one is reluctant to draw too many conclusions from the result. That is, however, an

overly pessimistic view. The process includes the variability or "chance"

221
that is inherent in using only two samples. That is precisely the value of

the Student's t Statistic. That calculatior. can be repeated for various

probabilities and various sample sizes. These curves are developed in

Figure 4.

100-

go- 0 2 TEST SAMPLE >-" I 3 3 TEST SAMPLE

S4 TEST SAMPLE

_• I....99 TEST SAMPLE

0 -"CURVES REPRESENT

Sn•I THE MAXIMUM ANTIC-

-. IPATED POPULATION

MEAN

0-

I I

0 0 0 0 0 0 0

In 0 o0

UNCONFINED COMPRESSIVE STRENGTH. PSI

Figure 4. Influence of sample size on confidence level

Figure 4 ill,;strates several important points that should be explored.

The mean strength does not vary significantly with the number of tests. At

first glance that suggests a certain reliability to the data. However, a comfarison of the curves for 2, 3, and 4 tests indicates that the probability

that the maximum population mean will not exceed certain values is very sensitive to the number of tests for small numbers of tests. As a corollary to

that, it may be said that the probability is relatively insensitive to the

number of tests when the number of tests is large. That is the characteristic

of the Student's t distribution. The point is clearly made below (2):

n n-i t(p = 0.90)

2 1 3.07768

3 2 1.88562

4 3 1.63775

10 9 1.38303

99 98 1.29104 (Interpolated)

In the ordinary course of geotechnical practice, where the sampling is

random and tests are conducted with precision, 10 to 12 tests will usually

provide adequate confidence levels.

222
Figure 4 is a method of quantifying the variability of the parameter

being studied. With this kind of analysis, an investigator has a rational

basis for deciding when sampling and results of tests are adequate for the

intcnded purpose.

The example used represents data acquired from a real project investigation and it is useful to assess the quality of the data that was actually used

to estimate project requirements.

Figure 3 contains a shaded area that represents the data on which cost

estimates were based. The shaded area represents two tests and it is obvious

that they lie at the extreme low end of the distribution curve and hence do

not reflect the characteristics of the population as they were ultimately

defined. The anticipated maximum population mean determined from these two

tests appears on the left of Figure 4. Maximum anticipated strength values

based on only these two tests are significantly different from what would have

been indicated if only four to six more random samples had been collected.

Together these curves show that it is essential to acquire a sample that

is adequate to limit excessive deviations at relatively low probabilities. An

adequate sample can be achieved by relatively few rock cores randomly selected

and tested with precision.

Figure 5 is the same use of the Student's t dist,.ibution to depict a

spectrum of the data. This ha. been constructed on the basis of the entire

100--- ___- ---

so -- -2 SAMPLES

0

CL60--- 

__

5o

0 0o 0 0 0

0

UNCONFINED COMPRESSIVE STRENGTH. PSI

Figure 5. Limits of population mean as a function of

probability

223
data set in Table 1 (12 samples). Figure 5 is a useful and reliable presentation of the data and one that clearly quantifies the variability of the

parameter being measured in a way that is meaningful to those requiring the

data. The essential point of Figure 5 is that it takes relatively few tests

to provide a reliable definition of the range of-an important characteristic.

Presentation

Geotechnical investigations are conducted by geotechnical engineers for

the use of others. In that respect, they must be comprehensible to other than

geotechnical engineers. In the field of dredging, geotechnical data is

perhaps the key element entering into the estimate of project costs, which is

of universal interest. It is exceedingly rare that a geotechnical engineer

will find himself preparing cost estimates for a dredging project, although he

may be consulted with respect to certain aspects of that data.

The labt element of Figure 1 contains the normal mechanisms for transferring data from the inves-.gator to the user and requires a brief comment.

The U. S. Army Corps of Engineers has authored many publications intended

to provide guidance in the acquisition and dissemination of geotechnical "ata.

They are excellent guides to investigation and presentation of data and they

should be familiar to any geotechnical engineer who accepts the responsibility

of a dredging project. One statement merits a direct quote.

Particular attention will be givei in clearly presenting those characteristics of ;'o-7-- that will

convey to the contractor accurate intormation on

excavation problems whereby he can determine what

excavation zuethods and procedures will be involved.

Complicated descriptions of scientific interest, but

not pertinent to the excavation problem, will be

eliminated (3).

If the term "materials" is substituted for "rock," the paragraph is sage

advice of universal application in dredging.

The task of the geotechnical engineer remains that of describing the

engineering properties and variability of the materials likely to be

encountered. The techniques are well known. It remains only to make certain

that these techniques are used and that the results are presented in a manner

that is informative to those charged with execution of the projecc.

REFERENCES

1. Lumb, P. 1974. "Application of Statistics in Soil Mechanics," Chapter 3

in Soil Mechanics - New Horizons, I. K. Lee, ed., Newness-Butterworths,

London, pp 44-111.

2. Lee, I. K., White, W., and Ingles, 0. G. 1983. Geotechnical Engineering,

Pitman.

224
3. Headquarters, Department of the Army. 1961. "Engineering and Design,

Presenting Subsurface Information in Contract Plans and Specifications,"

EM 1110-1-1806, Washington, D.C.

225
BENEFICIAL USES OF DREDGED MATERIAL: AQUACULTURE

IN DREDGED MATERIAL CONTAINMENT AREAS

John D. Lunz

Environmental Laboratory

U. S. Army Engineer

Waterways Experiment Station

PO Box 631

Vicksburg, Mississippi 39180

ABSTRACT

Aquaculture can be a profitable and biologically

beneficial use of containment area real estate. Aquaculture in a dredged material containment area was

first demonstrated by the Corps of Engineers (CE) with

limited success in Texas in 1976. The Texas project

documented that white shrimp could be grown to a

marketable size and quality in an environment designed

for and modified by dredged material disposal. Project

economics at that time did not support the practical

application of the concept. Currently, successful

American aquaculture industries for oysters, clams,

crayfish, catfish, trout, and other species, and developing industries for marine and freshwater shrimp,

mussels, and other species indicate continually improving economic conditions and incentives for expanded

aquaculture incentives. Progressive growth of American

aquaculture is a result of advancements in culture and

product processing technologies, more effective marketing strategies, and an increasing demand for fishery

products by domestic and foreign consumers.

Containment area aquaculture offers several inherent economically attractive features. Dredged material

containment areas are commonly diked and employ water

level control devices. In some instances costs

associated with land acquisition and dike and water

level control device construction are absorbed wholly

or in part by the Federal government or the local

cooperator on the dredging project such as a city

government or port authority. Freshwater and coastal

containment areas are often located near favorable

water sources, on water front property that might

otherwise not be available to the aquaculturist, and/or

near large market areas with established transportation

routes.

At a time when commercial aquaculturists are saying that the lack of available coastal sites has been

the principal restraint on the application of

226
commercially practical culture technologies, coastal

lowland availability could be increased for culturists

willing to operate in a containment area.

A CE-sponsored 2-day workshop on aquaculture in

dredged material containment areas was conducted in

1982. The proceedings of the workshop are briefly

summarized and include discussions about: site characteristics; site acquisition and permitting; contaminated dredged material; economics; pond design and

construction; pond operation and management considering water quality, production, and disease control

techniques; operational compatibility between dredged

material disposal and equaculture; and prospects for

success.

The necessary, preliminary desk-top analyses have

taken the idea as far as possible. Before the concept

is likely to be tried by an American aquaculturist

working together with coordinated CE dredged material

containment operations, a successful, full-scale field

demonstration will need to be conducted. Such a demonstration will probably require Federal subsidy.

BENEFICIAL USE OF DREDGED MATERIAL

The term "beneficial use of dredged material" describes the viewpoint

that dredged material and dredged material containment areas (DMCA) are very

often manageable resources. This positive viewpoint is being cultivated

intentionally within the Corps of Engineers to assist the ever-challenging

programs of dredged material management being conducted by Corps Districts.

The preference for a pcsitive rather than negative viewpoint of dredged

material is the reason why some in the Corps discourage the use of the term

"dredge spoil."

There are numerous examples of beneficial uses of dredged material and

dredged material containment areas (1),(2). This paper will discuss aquaculture as one of the beneficial multiple uses of containment areas.

CORPS OF ENGINEERS INTEREST IN CONTAINMENT AREA AQUACULTURE

The point of view that active dredged material containment areas are

unproductive, commercially unusable, and incompatible with local needs can be

dispelled by demonstrating that there are situations where aquaculture can be

a profitable ard biologically productive use of containment area real estate.

The use of dredged material containment areas for aquaculture would

directly benefit the Corps in several ways. It would improve future site

availability by increasing the value of acreage leased to dredging projnct

sponsors because landowners could enter separate and profitable lease agreements w:.th aquaculturists. Aquaculture activities would also dispel the

negative image of containment areas in the public eye, and generate a positive

public image of the Corps and its activities.

227
•.-. . .. .. . -- '.`-r`. 7 .- -, •- - .r;4`•.-•. 7• • • • . --.- • ;. -L `- .-- - - -* -• * ,, * . -

AN EARLY FIELD DEMONSTRATION

Aquaculture in a dredged material containment area was first explored by

the Corps during the Dredged Material Research Program. In 1976, Dow Chemical

Company, under contract to the Corps, successfully cultured a crop of white

shrimp (Penaeus setiferus) in an active containment area near Freeport,

Texas (3). The location was a 158-acre containment area adjccent to the Gulf

of Mexico along the Gulf Intracoastal Waterway (GIWW) (Figure 1).

Figure 1. Shrimp culture pond site. Location of the shrimp

pond site in dredged material containment area

No. 85 near Freeport, Texas (3)

Approximately 3 months before Dow Chemical began its operat-.ons, nearly

I million cubic yards of fine-textured dredged material was placed into the

area. Because an area of 158 acres was too large to manage easily, it was

partitioned by a 1000-ft-long internal levee to create a smaller 20-acre pond

(Figure 2). The pond was filled with water from the GIWW and the water was

poisoned with rotenone to destroy the predators and competitors that would

tend to reduce the survival of the animals to be cultivated. Fertilizer was

then added to encourage the growth of planktonic algal food for "he juvenile

white shrimp that were to be released into the pond. After stocking, shrimp

were retained in the pond for 3 months without supplemental feeding. At the

end of the 3-month period, shrimp were harvested, analyzed, and determined to

be wholesome for human consumption.

This demonstration project permitted the conclusion that dredged material

containment area environments are compatible with aquaculture in the sense

that animals will grow, survive, reach marketable size, and be of marketable

quality. No attempt was made to justify the project's production economics

and it is certain that an economic analysis would not have been encouraging.

The cost of postlarval white shrimp stock, limited acreage, and small size of

the unfed white shrimp at the time they were harvested all contributed to

extraordinarily high production costs.

228
. .. ...

Figure 2. Galveston District dredged material containment area

No. 85, showing shrimp pond, internal levee, and

associated structures (3)

REVISITING THE CONCEPT IN LIGHT OF NEW TECHNOLOGY AND

OTHER FACTORS

Advances in Aquaculture Technology

Many of the technology problems encountered which affected production

economics during the early demonstration at Freeport have been reduced through

continuing research on the biology and culture requirements cf desirable plant

and animal species. It is now possible, for example, under laboratory

conditions to complete the life cycle of the white shrimp species used in

Freeport. By mani,,' 1 4.ing the female shrimp's environmental conditions and

hormone levels, it's possible to control the entire maturation process in the

laboratory. Females can then be artificially inseminated. One advantage of

this technology is a much reduced cost of obtaining juvenile shrimp compared

with the cost of field excursions for capturing egg-carrying and recently

mated female shrimp in the wild, and returning them to a laboratory for

spawning. Another very significant advantage is that artificial control over

the natural reproductive cycle permits production of juvenile shrimp whenever

they are needed and allows production of multiple crops in a single growing

season. The result is more efficient use of the cultivation area, higher

annual production, and lower net production costs.

In the United States at the present time, important aquaculture industries exist for oysters, clams, crayfish, catfish, trout, and other qpecies.

New industries are developing for culture of shrimp, nrawns, mussels, and

others. These industries, and aquaculture-based fisheries, contribute

hundreds of millions of dollars annually to the American economy and help

reduce a major trade deficit (4).

229
Increasing Demand for Fishery Products

and the Contribution of Imported

Fishery Products to the National Trade Deficit

According to Lawrence, Chamberlain, and Hutchins (5), the dockside value

of all U. S. fisheries is consistently more than $2 billion a year. In 1980,

it was $2,237,202,000. In that same year, the United States imported fishery

products valuei at $3,648,082,000. These authors stated that the importation

of foreign fishery products accounted for 10 percent of the national trade

deficit in 1979. Using the shrimp fishery as an example, the value of the

U. S. catch decreased from $471,573,000 to $402,697,000 between 1979 and 1980,

whereas the value of shrimp imports for human consumption increased from

$713,238,000 to $719,263,000 during the same period. They further predicted

that the imbalance will increase because the U. S. demand for fishery products

is constantly increasing at a time when fishery harvests are at or near

M maximum sustainable yields.

Apparently Favorable Economics

of Containment Area Aquaculture

Dredged material containment areas commonly possess structural features

such as dikes and water control devices that may enhance their suitability as

multiple-use areas with aquaculture. In somi instances, land acquisition "costs (purchase or lease) and dike and watet control structure costs are

"absorbed wholly or in part by the Federal Government or a local cooperator on

the dredging project such as the city government or port authority. In cases

vwhere a Federal or local subsidy exists, the aquaculturist could be the beneficiary. Dugger (6) stated that the lack of available coastal sites has been

the principal restraint on the application of commercially practical culture

technologies. He used the term "availability" with reference to both the real

estate cost and to the government's regulatory permitting process which

"affects consideration of aquaculture in coastal lowlands, particularly wetland

"habitats of the United States. Lunz and Homziak (7) stated that freshwater

and coastal dredged material containment areas have several benefits related

to desirable location: proximity to favorable water sources, on waterfront

property that may otherwise be unavailable to the aquaculturist, aind often

near large market areas and established transportation routes.

Proposals to use coastal lowlands or wetlands for dredged material

containment are subject to Federal and/or state wetland protection regulations. At least two different scenarios are apparent that would improve coastal lowland availauility to aquaculturists willing to operate in a containment area. In the first scenario, obtaining permission to use an existing

disposal area for aquaculture was precedented and seemed to be a relatively

simple procedure. Unfortunately, the area for which permission was obtained

was never used because of a shortage ef capital. In the second scenario, the

local, regional, and economic benefits described in a permit application that

included both dredging-related and aquaculture-related incentives would be

greater than the benefits described for a single-use project. The probability

of a successful permit action is thereby improved.

Dikes that would serve to contain the dredged material would also serve

to impound the water necessary for aquaculture. But the quality of dikes

"230
constructed in different areas for the sole purpose of dredged material

containment is highly variable as illustrated by Figu,;es 3 and 4. The dikes

Figure 3. Double bayou containment area dike in Texas

(photos in this paper were provided by

Mr. Rick Medina, U. S. Army Engineer

District, Galveston)

of an exfstinS containment area that is under consideration for aquaculture . may have to .ý- mo'tified to increase their height, adjust their slopes, or

*-. improve Lheir ,:at.r-retaining capabilities. However, at a new containment

area that has be-n :identified for multiple use, the dikes could be designed to

nermit borb the c.o, :ainment of dredged material and the retention of water for

the aquaculture up:zation.

Water contr. structures that are used to regulate water quality at

"* containment are~s could also serve to regulate water exchange rates and levels

iii an aquaculture pond, and could be used to drain the pond or concentrate the

%rop for harx-sting. A weir-type structure (Figure 5) located within the dike

perimeter system itself and the drop-inlet-type structure (Figure 6) located

inside the dike perimeter are two designs commonly used in containment areas.

Compatibility Between Aquaculture and Dredged Material

Management in Containment Areas

"There are at least two general containment area management techniques

that could be compatible with aquaculture. Figure 7a depicts the placement of

dredged material into a containment area surrounded by a single primary dike

"system. Distribution of the dredged material would be dependent on the size

(surface area) of the containment and the relative volume and physical

231
Figure 4. Containment area dike in Texas

Figure 5. Weir-type spillway structure used in dredged

material containment areas

232
Ao

Figure 6. Drop-inlet-type spillway structure used in

dredged material containment areas

a. PERIODIC DISPOSAL INTO THE ENTIRE SITE.

b. SCHEDULED DISPOSAL INTO SITE-CELLS.

t - time in years and may vary betwee" I and 15 from site to site

Figure 7. Concepts for combining dredged material containment

and aquaculture operations

233

'I
characteristics of the dredged material, together with controlled disposal

operation conditions like pipeline placement and movement. It is unlikely,

though not impossible, that culture operations could be sustained within a

Figure 7a-configured site during active disposal. A small volume of dredged

material disposed into a large containment area together with a species

tolerant to suspended sediments is one workable scenario. Figure 7b depicts a

containment area divided into multiple compartments or cells which would be

filled sequentially over the life of the area. Construction of secondary,

internal dikes produces a configuration with numerous operational advantages

over an undivided one. The most obvious benefit would be related to the

separation of one or more cells from dredged material disposal for an extended

period of time. A more or less continuous aquaculture operation would be

possible in such a site even during dredged material disposal operations. The

7b configuration has an additional benefit in a new site because it also

separates the aquaculture operation from potentially chemically contaminated

dredged material--a source of perceived even if not actual production or

marketing problems.

The length of time following a disposal event before aquaculture

activities could begin would be a site-specific variable depending on the

site's size and configuration, the volume and character of the dredged

material, and the possible use of dredged material dewatering and other

volume-reducing techniques for efficient containment area management. A site

without cells may not be available to aquaculture during the active dewatering

period. Otherwise, aquaculture and dewatering objectives are totally

compatible.

WORKSHOP ON CONTAINMENT AREA AQUACULTURE

A Corps-sponsored, 2-day workshop on aquaculture and dredged material

containment areas was conducted in 1982 (8). It was attended by about

125 persons representing the Corps, other Federal agencies, state agencies,

the aquaculture industry, the commercial fishing industry, and the academf'

research community. The specific objectives of the workshop were to:

a. Assess the utility of current aquaculture technology and its possible

application to containment area aquaculture.

b. Identify research needs in containment area aquaculture.

c. Assess the potential for aquaculture in containment areas containing

contaminated material.

d. Discuss user guidelines for establishing and operating aquaculture

facilities in containment areas.

e. Propose designs for an economically attractive program of multiple

use of containment areas for dredged material disposal and

aquaculture.

Presentations by invited speakers from both commercial operations and

research institutions occupied the first day of the workshop. A preliminary

session related available aquaculture technology to containment area

234
aquaculture, and identified similarities and differences. This session also

served as an overview of warmwater aquaculture practices and provided a common

technical base for all participants.

The second day was devoted to problem solving. Five discussion groups,

each consisting of a moderator-led core of specialists, were charged with

providing specific topic-related recommendations and guidelines for

establishing and operating profitable aquaculture facilities in dredged

material containment areas.

A list of invited papers, speakers, discussion group topics, and group

moderators is given in Table 1. A summary of the significant discussions is

presented below.

TABLE 1. WORKSHOP AGENDA

Title Speaker/Moderator

Plenary Session

Welcome COL Alan Laubscher

Galveston District Engineer

Opening Remarks Mr. Jesse Pfeiffer

Directorate of R&D, OCE

Site Description of DMCAs: Overview Hr. Rick Medina

of Physical, Chemical, and Biological Galveston District

Features

Applicability, Cost, and Benefits of Mr. John Lunz, WES

Aquaculture in Containment Areas

Operating an Aquaculture Facility in

a DMCA:

Legal Framework Mr. Durwood DugEer and

Mr. Michael Roegge

Commercial Shrimp Culture

International, Inc.

Production Economics Dr. Addison Lawrence

Texas A&M University

(TAMU) Marine

Experiment Station

(Continued)

235
TABLE 1. (Continued)

Title Speaker/Moderator

Plenary Session (Continued)

Review of Species Suitable for

DMCA Culture:

Fresh Water Dr. Robert Stickney

TAMU

Marine Mr. Walter Tatum

Claude Peteet Mariculture

Center

Market Economic of Dr. John Waldrop and

Potential Products Dr. James Dillard

Mississippi State University

Pond Management:

Polyculture versus Dr. R. Kirk Strawn

Monoculture TAMU

Water Quality Criteria Mr. William Hollerman

and Control Auburn University

Health and Disease Control Dr. Ken Johnson, TAMU

Predator and Competitor Mr. Walter Tatum

Control, Feeding/

Fertilization, and Environmental Modifications

Aquaculture in Rice Field Dr. John Dean

Impoundments: Model for University of South

DMCA Culture Carolina

Selection Criteria and Proce- Mr. Dennis Milligan

dures for Eatablishing Aquaculture Dow Chemical USA

Facilities in Existing DMCAs

DMCA Design for Multiple Use: Mr. Richard H. Highfill

Aquaculture and Dredged Material USDA Soil Conservation

Containment Service

Use of Contaminated Dredged Dr. Henry Tatem, WES

Material Containment Sties:

Possible Problems and Alternative Uses

(Continued)

236
TABLE 1. (Concluded)

Title Speaker/Moderator

Discussion Groups

Laws Governing Acquisition, Mr. Rick Harrison

Maintenance, and Operation of Galveston District

DMCAs

Target Species Selection and

Management:

Marine/Brackish Water Dr. David Aldrich

TAMU - Galveston

Fresh Water Dr. Robert Romaire

Louisiana State University

Aquaculture Operations in Mr. James Andreasen

Contaminated Material Disposal Field Research Station of

Sites the Columbia Laboratory

Mr. James Mansky

New York District

Economics of DMCA Aquaculture Mr. Michael Jones

TAMU Mariculture

Laboratory

Legal Aspects of DMCA Mr. Bart Theberge

Aquaculture Virginia Institute of

Marine Science

Benefits of Containment

Areas to Owners, Users,

and the Corps of Engineers

Parties involved in commercial containment area aquaculture could realize

significant benefits from multiple use of containment areas. Freshwater and

coastal containment areas offer the benefits of desirable location and reduced

construction and maintenance costs to aquaculturists/entrepreneurs. Local

public interests could gain from the development of containment area aquaculture through employment opportunities and enhanced tax revenues.

A financially profitable multiple use of containment areas would also

benefit owners of disposal acreage and the Corps. Propcrty owners would

receive compensation for the use of their land both as a containment area and

for aquaculture. This would serve as a financial incentive to property owners

237
to make acreage more readily available for containment of dredged material.

In addition to the improved real estate availability, the Corps would benefit

from positive publicity generated by its efforts to cooperate with local

interests and from promoting the use of what had been popularly perceived as

biologically and economically unproduct:.;e acreage.

Aquaculture Products

Aquaculture in containment areas could be designed to produce crops for

commercial harvest or could be directed toward producing fish or shellfish

stocks for release to augment depressed natural populations. Current

aquaculture-for-reldase programs in California, Texas, Japan, and the Middle

East use natural and artificial coastal ponds, lagoons, and embayments for

their propagation programs (9),(10). Similar programs could easily be

undertaken in containment areas.

Coastal impoundments and containment areas used for the culture of fish

and shellfish can serve as prototypes illustrating the feasibility of containment area aquaculture. Fish, shrimp, crabs, and crayfish raised with a minimum management effort have been harvested from old rice field impoundments in

South Carolina (11). An infrequently used contain ment area in Sabine Lake in

Port Arthur, Texas, produced marketable crops of redfish, shrimp, and crab,

again with little management effort (12). Shrimp cultured in a containment

area near Freeport, Texas, as part of the Corps' Dredged Material Research

Program were found to grow well and produce a wholesome crop (13). To

emphasize the continuing interest in impoundment/containment area aquaculture,

commercial concerns represented at the workshop had leased such acreage for

aquaculture development.

Areas of Concern/Potential Problems

Site characteristics

Containment areas exhibit a wide range of variability; location, size,

construction, compatibility of aquaculture with disposal requirements, and a

myriad of other site-specific physical and chemical features make each

contai-ament area unique. Not all containment areas will be suitable for

aquaculture, but a significant number have the proper combination of features

to support aquaculture. Crucial to developing aquaculture as a secondary use

of containment areas is the fact that aquaculture will be possible only if it

is compatible with the dispoaal requirements and schedules imposed by the

intended primary use of the site, i.e. dredged material disposal. Only when

both the aquaculturist's and the disposal agency's requirements are met can

the site be developed for aquaculture.

Site acquisition and permitting

Site development and pond management practices are expected to be similar

to those presently used in commercial aquaculture operations. Major exceptions lie in the areas of site acquisition by entrepreneurs and permit-granting procedures. Existing easement agreements must be amended, requiring prospective

aquaculturists to reach separate agreements with both the property owner and

the Corps. Representatives of commercial aquaculture enterprises claim that

238
the current permitting process is so involved and complex that the growth of

aquaculture in the United States is effectively thwarted. Having the Corps

involved in promoting and developing aquaculture in addition to retaining its

traditional role in the permitting process would, in the view of many of the

workshop participants, expedite the process in the future.

Use of contaminated sediments

The question of sediment contaminants and their possible effects on

cultured organisms was another important area of concern. Material dredged

from areas with heavy navigation traffic usually contain contaminants. The

results of recent experiments designed to determine the effects of high

contaminant concentrations on marine and freshwater organisms suggest that

even high contaminant levels in sediments do not necessarily produce toxic

effects in test organisms nor do they promote the accumulation of large concentrations of contaminants in the tissue of these organisms. Of course,

these results vary with the type of contaminant, sediment conditions, and

species of organism.

While information is lacking on many aspects of contaminant effects on

species of interest to aquaculturists, this was not viewed as a problem.

Caution and additional research were advised in dealing with potentially

contaminated sediments.

Economics

From nn economic veiwpoint, containment area aquaculture appears favorable. Participants with experience in both finfish and shrimp culture pointed

out the great degree of similarity in the economic and marketing requirements

between current aquaculture operations and those proposed for containment

areas. Capital investment requirements could be significantly less. Simplified land acquisition, reduced land costs, shared costs of dike construction

and maintenance expenses, and an expedited permitting process would all contribute to reducing capital costs. Operating costs, depending on both site

and species cultured, were not so readily analyzed. But no extraordinary

additional costs were anticipated.

Physical plant

Pond construction and modification for aquaculture would be site- and

species-specific. If a containment area satisfied initial geotechnical and

engineering requirements, constructing additional dikes, installing water

control equipment, and other necessary modifications should follow the procedures employed in conventional operations. Cooperative efforts involving

aquaculturists, the U. S. Department of Agriculture Soil Conservation Service,

and tha Corps were recommended for developing designs and specifying any modifications necessary for using containment areas for aquaculture.

Management concerns

Health considerations, water quality, and species management techniques

for containment area culture should be identical to current practices, although

the effects of large amounts of fine sediment in the containment area ponds

239
and the lack of experience in managing large-scale aquacuiture operations pose

questions that still need to be answered. Management procedures for large

ponds have not been developed for many species simply because large ponds have

not been generally available. With increased availability afforded by the

widespread use of containment area acreage, appropriate techniques will

rapidly evolve. Similarly, adequate water exchange, aeration, and harvest

techniques should overcome many difficulties created by the presence of large

amounts of fine sediments.

Compatible activities

Dredged material disposal and aquaculture can coexist in several ways.

Crops may be cultured between disposal events, as in the Freeport demonstration, or the containment area may be subdivided into cells to be filled

sequentially, permitting concurrent aquaculture and disposal operations in

separate cells. With either system, aquaculture operations would cease as the

containment area approached capacity.

Prospects of success

The conclusions of the plenary session and group discussions were that

aquaculture in active containment areas was a feasible, cost-effective, and

compatible multiple use of containment areas. With rare exceptions, existing

technology could be directly applied to containment area aquaculture, making

the concept practical with little additional research and development investment required. Those problem areas and research needs identified during the

workshop were judged to be tractable and would not hinder the application of

this concept. The needs of the local area, interests of the involved parties,

and technical constraints will determine wtich type of culture operation

(commercial or stock augmentation) and which species would be most suitable

for a given area.

Prospects for culture of freshwater organisms in dredged material containment areas are bright. The large successful industries centered on crayfish, catfish, trout, and bait minnows can provide both the technical

expertise and sources of stock needed for developing a profitable operation.

The technology involved in freshwater fish culture is both well defined and

compatible with culture plans envisioned for containment areas.

Redfish, exotic and native shrimp, hybrid striped bass, bait shrimp and

minnows, and waterfowl are the most promising species for marine/brackish

water culture. In contrast with the status of freshwater species aquaculture,

the technology for the culture of many marine species has only recently

advanced to the commercial level. The completion of shrimp life cycles under

laboratory conditions, developing redfish propigation techniques, and other

recent biological advances permit a cautiously optimistic assessrent of the

prospects for the culture of these and other marine species.

Workshop participants reached a consensus that aquasulture as a secondary

use of containment areas would be both profitable and desirable. Pilot-scale

demonstration projects under various field conditions and research directed at

the potential problem areas were recommended. The technical infcrmation

shared at the workshop and the support generated for this concept by the

240
represented agencies and interests combined to provide a solid foundation for

the further development of the aquaculture concept.

The proceedings of the workshop are available and can be obtained by writing to the author.

THE FUTURE OF CONTAINMENT AREA AQUACULTURE

Aquaculture is a capital-intensive, risky enterprise. Money-lending

institutions are reluctant to provide loans to aquaculturists operating under

conditions that are new, different, unprecedented, and therefore too

risky (6). In order for the private sector to adopt a concept that has been

evolving so positively to date, it will be necessary to conduct, document, and

advertise the results of a successful, real-scale field demonstration project.

The existence of the results of the Freeport, Texas, field study conducted in

1976, the awareness of new technologies, the more attractive economic conditions, and the consensus of the workshop participants about the melits of the

concept and the prospects of success are simply not adequate to induce the

private sector to invest a million or more dollars in the concept. Huguenin and Webber (13) discussed the transition and scale-up of research results to

commercial marine aquaculture systems. They stated,

Some scientists viewed the development of marine aquaculture as strictly a biological and biochemical

problem. The problems most commonly mentioned as

limiting are disease control, nutrition, and larval

rearing. The role of the technologist is usually

viewed basically as providing support in the development of experimental equipment. Large scale systems

management aspects are generally not even considered.

The hope is to carry out sufficient experimentation in

the laboratory so as to answer all the critical questions limiting large scale practical applications. Only then is it judged necessary to factor in

seriously the engineering, marketing, and economic

aspects. Many of the f&ilures to date can be partial- ly attributed to this neglect of the basic problems

involved. Probably the biggest misunderstanding is

the assumption that the scale-up of laboratory experiments to commercial size is a low-risk, straightforward linear bioengineering process. Thus, it is

considered that there is little need for engineering

or systems management input to experimental design or

determining priorities required to guide research

efforts into productive channels.

Table 2 is reprinted from their paper and presents the many basic differences in objectives, criteria, and other features when experimental systems

and much larger applications are compared.

The merits of the concept are unquestionable. But the critical desk-top

analyses have taken the idea about as far as it can go. Before the concept Is

241
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likely to be tried by &n American aquaculturist working together w1th coordinated, Corps dredged material containment operations, a Federally subsidized

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REFERENCES

1. Spaine, P. A., Llopis, J. L., and Perrier, E. R. 1978. "Guidance for

Land Improvement Using Dredged Material," Technical Report DS-78-21,

U. S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss.

2. Walsh, M. R., and Malkasian, M. D. 1978. "Productive Land Use of Dredged

Material Containment Areas: Planning and Implementation Considerations,"

Technical Report DS-78-20, U. S. Army Engineer Waterways Experiment Station,

CE, Vicksburg, Miss.

3. Quick, J. A., Milligan, D. J., Hill, S. E., Hover, R. J., and

Mcllhenny W. F. 1978. "Field Demonstration of Shrimp Mariculture Feasibility in Dredged Material Containment Areas," Technical Report D-78-53,

U. S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss.

4. Sandifer, P. A. 1983. "Status cf Aquaculture Technology," Presentation

made before the Beneficial Uses Panel 1 (biological) and abstract

published in the Report to the Chief of Engineers on Thirty-Fourth Meeting

of the Environmental Advisory Board, 1-3 March 1983, dealing with

beneficial environmental aspects of the Corps' dredging program, Office of

the Chief of Engineers, Washington, D. C.

5. Lawrence, A. L., Chamberlain, G. W., and Hutchins, D. L. 1981. "Shrimp

Mariculture; An Overview," TAMU-SG-82-503, Texas A&M University Sea Grant

Program, College Station, Tex.

6. Dugger, D. M. 1983. "Commercial Aquaculture in Dredged Spoil Containment

Areas: An Industry Viewpoint," Presentation made before Beneficial Uses

Panel I (biological) and abstract publ.1hed in the Report to the Chief of

Engineers on the Thirty-Fourth Meeting of the Environmental Advisory Board,

1-3 March 1983, dealing with beneficial environmental aspects of the

Corps' dredging program, Oifice of the Chief of Engineers, Washington,

D. C.

7. Lunz, J. D., and Homziak, J. 1983. "Aquaculture in Dredged Material

Containment Areas: An Assessment of the Prospects," Presentation at

Aquaculture 83, January 1983, Washington, D. C.

8. Homziak, J., and Lunz, J. D. (eds.). 1983. Aquaculture in Dredged

Material Containment Areas; Proceedings, Miscellaneous Paper D-83-2,

U. S. Army Engineer Waterways Experiment Station. CE, Vicksburg, Miss.

9. Kittaka, J. 1981. "Large Scale Production of Shrimp for Releasing in

J.pan and in the United States and the Results of the Releasing Programme

at Panama City, Florida," Kuwait Bulletin of Marine Science, Vol 2,

pp 149-163.

243
10. Kurata, H. 1981. "Shrimp Fry Releasing Techniques in Japan, with Special

Reference to the Artificial Tideland," Kuwait Bulletin of Marine Science,

Vol 2, pp 117-147.

* 11. Dean, J. M., Wilson, C. A., and Alon, N. C. 1983. "Mariculture in Old

Rice Field Impoundments: An Analog for Dredged Material Containment

Areas," Aquaculture in Dredged Material Containment Areas; Proceedings,

Homziak, J., and Lunz, J. D. (eds.), Miscellaneous Paper D-83-2,

U. S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss.

12. Ford, B. 1982. "Moon Lrothers Shrimp Heaven Hits Hard Times," Beaumont

Sunday Enterprise - Journal, 26 September 1982 edition, Beaumont, Texas.

"13. Huguenin, J. E., and Webber H. H. 1981. "The Transition and Scale Up of

Research Results to Commercial Marine Aquaculture Systems," Proceedings

of the Bioengineering Symposium for Fish Culture, Allen, J. L., and

Kinney, E. C. (eds.), Published by the Fish Culture Section of the

American Fisheries Society, Bethesda, Maryland, and the Northeast Society

of Conservation Engineers.

244