AD-A253 002

US Army Corps

of Engineers

Water Resources

Support Center

Management of Bottom Sediments

Containing Toxic Substances

Proceedings of the 12th U.S./Japan

Experts Meeting

11-14 November 1986

Yokohama, Japan DTIC _ ELECTE

JUN0,5 1992

Thomas R. Patin, Editor A l0

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

the U. S./Japan Experts Meetings (12th) Held in Yokohama, Japan on

11-14 November 1986

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MANAGEMENT OF BOTTOM SEDIMENTS CONTAINING TOXIC

SUBSTANCES: PROCEEDINGS OF THE 12TH U.S./JAPAN

EXPERTS MEETING

6. AUTHOR(S)

Thomas R. Patin, Editor

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Water Resources Support Center AGENCY REPORT NUMBER

Fort Belvoir, Virginia 22060;

USAE Waterways Experiment Station, Environmental

Laboratory, 3909 Halls Ferry Road, Vicksburg,

MississipDi 39180-6199

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13. ABSTRACT (Maximum 200 words)

The 12th U.S./Japan Meeting on Management of Bottom Sediments Containing

Toxic Substances was held 11-14 November 1986 in Yokohama, Japan. The meeting

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

the Japan Ministry of Transport to provide a forum for presentation of papers

and in-depth discussions on dredging and disposal of contaminated sediment.

14. SUBJECT TERMS 15. NUMBER OF PAGES

Dredging Sedimentation 341

Marine deposits Toxicology 16. PRICE CODE

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

OF REPORT OF THIS PAGE OF ABSTRACT

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298 102
PREFACE

The 12th U.S./Japan Experts Meeting on Management of Bottom Sediments

Containing Toxic Substances was held 11-14 November 1986 in Yokohama, Japan.

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

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

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

contaminated sediment.

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

Support Center (WRSC), was the U.S. Chairman. Mr. Takao Nishimura, 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 Engineer Waterways Experiment Station (WES),

Vicksburg, Miss. Mr. Charles C. Calhoun, Jr., was Program Manager, DOTS, at

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

DOTS Program.

Acce3ion For

NTIS CRA&I

DTIC TF.3

JusterctioL~i.....

Y...... .. .... ..... ......

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Dist spcý;iai

A-(-
CONTENTS

PREFACE .............................. ................................ 1

AGENDA .............................. ................................ 4

BEACH RECLAMATION AND DREDGED MATERIAL DISPOSAL FOR

MARINE ENVIRONMENT IMPROVEMENT by Y. Matsubara ......... ........... 8

RESEARACH CONSIDERATIONS OF PHYSICAL FACTORS RELEVANT

TO DISPOSAL OF CONTAMINATED DREDGED MATERIAL

by L. Vallianos .................... ........................... .. 18

DEWATERING AND REUSE OF WATER BLOOMS IN THE LAKE AND

THE PORT by Z. Yoshino, K. Sato, H. Okajima, A. Kasai,

K. Unakami, S. lida, A. Miyamoto, T. Kotake, R. Sudo,

and M. Okada .................... ............................ 27

LAKE SUWA IS BEING RESTORED by T. Yoshida ........ ............... .. 44

MOVEMENT OF TURBID WATER IN RECLAIMING by H. Kojima, E. Yauchi,

M. Gomyoh ...................... .............................. 63

DREDGED MATERIAL DISPOSAL MANAGEMENT STUDIES FOR THE PORT OF

NEW YORK AND NEW JERSEY: PROGRESS REPORT by J. F. Tavolaro

and J. Zammit .................... ............................ 70

PREVENTION OF SECONDARY POLLUTION CAUSED BY DREDGING BOTTOM

SEDIMENT CONTAINING MERCURY IN MINAMATA BAY by Y. Nakayama,

S. Watanabe, K. Kyuma, R. Hirota, and M. Fujiki .... ........... .. 89

CLEANER SIDIMENTS IN HIROSHIMA BAY--A TRIAL CLEANING PROJECT

USING SAND COVERING IN KURE INLET by H. Kakigawa, K. Takemura,

K. Mizobata, and S. Shibata .............. ..................... .. 107

PUGET SOUND DREDGED DISPOSAL ANALYSIS by F. J. Urabeck

and K. E. Phillips ..................... .......................... 133

REMOVAL WORK OF ORGANIC DEPOSIT BY OOZER PUMP DREDGE

by K. Fujii and F. Otsu ................ ....................... .. 159

SEDIMENT CONTROL ON LAKE EUTROPHICATION USING AND ECOLOGICAL

MODEL by M. Hosomi, R. Sudo, and M. Okada ....... ............. .. 185

NEW TECHNOLOGIES APPLIED AT MEINOHAMA LANDFILL by M. Tajiri

and H. Sekiya ...................... ............................ 202

THE ROLE OF MICROORGANISMS IN MOBILIZATION OF CONTAMINANTS

FROM SEDIMENT by D. Gunnison, L. K. Blum, and A. L. Mills ........ .. 222

TESTS ON SEDIMENT GAS GENERATION by T. Yoshida and K. Nikaido ..... ... 239

2
DEALING WITH TOXIC POLLUTED SEDIMENTS IN THE GREAT LAKES BASIN

by P. L. Wise ...................... ............................ 257

EVALUATION OF CHEMICAL POLLUTANTS BY ANALYSIS OF OIL COMPONENTS

IN SEDIMENTS by K. Ninomiya .............. ..................... .. 268

GAS GENERATION IN CANALS OF TOKYO PORT by Y. Matsumoto, Y. Ishii,

and K. Shimura ..................... ........................... 283

DEVELOPMENT OF THE PORT OF LONG BEACH: PAST, PRESENT, AND

FUTURE PROJECTS by C. F. Connors and E. C. Kelly ..... .......... 299

IMPACT ASSESSMENT OF IN-PLACE CONTAMINATED SEDIMENTS ON WATER

QUALITY: A CONCEPT by T. L. Hart, D. Gunnison, and J. Brannon . . . 323

PRELIMINARY STUDY OF THE ECOLOGICAL STRUCTURE OF BENTHIC ORGANISMS

IN TOKYO BAY by S. Sekiguchi, Y. Hirai, M. Yoshida, and K. Irie . . . 327
AGENDA

12th U.S./JAPAN EXPERTS MEETING ON MANAGEMENT

OF BOTTOM SEDIMENTS CONTAINING

TOXIC SUBSTANCES

Yokohama, Japan

11-14 November 1986

November 11, 1986

9:00-9:30 Opening Ceremony

9:00-9:10 Director-General of the Ports and ..arbors Bureau, MOT

9:10-9:20 Mayor of Yokohama City

9:20-9:30 Cochairman Col. Kleb

Mr. Nishimura

9:30-10:00 Beach Reclamation and Dredged Disposal for Marine

Environment Improvement

Presented by Yutaka Matsubara, Ports and Harbors

Bureau, Ministry of Transport

10:00-10:30 Research Consideration of Physical Factors Relevant

to Disposal of Contaminated Dredged Material

Presented by Limbarios Vallianos, U.S. Army Corps

of Engineers, Waterways Experiment Station (WES)

10:30-11:00 Coffee Break

11:00-11:30 Dewatering and Reuse of Water Blooms of the Lake

and Port

Presented by Zenya Yoshino, Science University of

Tokyo

11:30-12:00 Lake Suwa Is Being Restored

Presented by Tatsuo Yoshida, Japan Sediments

Management Association

12:00-13:30 Lunch

13:30-14:00 The Movement of the Turbid Water in Reclaiming

Presented by Eiji Yauchi, Japan Dredging and

Reclamation Engineering Association

14:00-14:30 Dredged Material Disposal Management Studies for the

Port of New York and New Jersey: Progress Report

4
Presented by John Zammit, U.S. Army Engineer

District, New York

14:30-15:00 Method on Watch for Prevention of Secondary

Pollution Caused by Dredging Work of Bottom

Sediment Containing Mercury at Minamata Bay

Presented by Koichi Kyuma, Environment Department,

Kumamoto Prefecture

15:00-15:30 Coffee Break

15:30-16:00 Aiming at Cleaner Sediments in Hiroshima Bay -

Trial Cleaning Project by Means of Sand Covering

in Kure Inlet and Its Effects

Presented by Hideaki Kakigawa, The 3rd District

Port and Harbor Construction Bureau, Ministry of

Transport

16:00-16:30 Puget Sound Dredged Material Disposal Analysis

Presented by Frank Urabeck, U.S. Army Engineer

District, Seattle

16:30-17:00 Removal Work of Organic Deposit by Oozer Pump

Dredger

Presented by Fujio Otsu, Japan Dredging and

Reclamation Engineering Association

17:00-18:^0 Free

18:00-20:00 Japan Reception

Yokohama International Conference Center Lounge

November 12, 1986

9:00-9:30 Assessment of Sediment Control on Lake

Eutrophication Using an Ecological Model

Presented by Masaaki Hosomi, Laboratory of

Freshwater Environment, National Institute for

Environmental Studies

9:30-10:00 New Technologies Applied at Meinohama Landfill Work

Presented by Masayoshi Tajiri, Japan Sediment

Management Association

10:00-10:30 Coffee Break

10:30-11:00 The Role of Microorganisms in Mobilization of

Contaminants from Sediment

Presented by Douglas Gunnison, WES-Environmental

Laboratory

5
11:00-11:30 Test on Sediment Gas Generation

Presented by Kiyoshi Nikaido, Japan Sediment

Management Association

11:30-12:00 Dealing with Toxic Polluted Sediments in the Great

Lakes Basin

Presented by Peter L. Wise, U.S. Environmental

Protection Agency

12:00-12:30 Evaluation of Chemical Pollutant by Analysis of Oil

Component in Sediments

Presented by Katsuyuki Ninomiya, Yokohama

Environmental Research Institute

12:30-13:30 Lunch

13:30-17:00 Yokohama City Excursion (Yokohama Port, etc.)

17:00-18:30 Movement

18:30-20:00 U.S. Reception (New Sanno Center, Tokyo)

November 13, 1986

9:00-9:30 Port of Baltimore: Present and Planned Management

of Contaminated Dredged Materials

Presented by Frank Hammons, Baltimore Port

Authority

9:30-10:00 Mechanism of Gas Generation in Canals of the Tokyo

Port

Presented by Yoshihiro Mat~umoto, Department of

Construction, Bureau of Port and Harbor, Tokyo

Metropolitan Government

10:00-10:30 Coffee Break

10:30-11:00 Development of the Port of Long Beach: Past,

Present, and Future Projects

Presented by Charles Connors, Long Beach Port

Authority

11:00-11:30 Preliminary Study on the Ecological Structure of

Benthic Organisms in Tokyo Bay

Presented by Masaru Yoshida, Japan Sediment

Management Association

6
11:30-12:00 Impact Assessment of Inplace Contaminated Sediments

on Water Quality

Authored by Dr. Tom Hart

Presented by Douglas Gunnison

WES-Environmental Laboratory

12:00-12:30 Signing of Joint Communique, Closing Remarks

12:30 -18:00 Free

18:00-20:00 Yokohama City Reception

(Hotel Yokohama Teishin Kaikan)

November 14. 1986

8:30 M. 0. T. Excursion

(Institute for Technical Research of Ports and

Harbors, Kamakura)

7
BEACH RECLAMATION AND DREDGED MATERIAL DISPOSAL FOR

MARINE ENVIRONMENT IMPROVEMENT

AD-P006 IMIIIII I IIII M III 895 HYut aka Mat subara

Environment Division

Ports and Harbors Bureau, Ministry of Transport

2-1-3 Kanumigaseki, Chiyoda-ku, Tokyo 100

INTRODUCTION

The Bureau of Ports and Harbors, Ministry of Transport, is engaged In a

number of sea bottom management operations. These operations consist of the

prevention of harbor pollution, implemented primarily by dredging bottom sediment, and a study of sea bottom sediment clarification designed to eliminate

organic sediment in bays and inland seas.

In implementing these projects, one very significant problem that must be

solved is disposal of the dredged material. Difficulties are also encountered

in disposal of the material produced from the improvement works of port facilities, fairways, and anchorages. These difficulties occasionally block the

implementation of such projects.

This paper describes examples of the disposal of, or use of, certain

types of dredged material and organic sediment for beach reclamation.

BACKGROUND

Japan is surrounded by the sea, arnd the productive activities and life

styles of the Japanese people were once closely related to the sea. In particular, beaches and tidelands played important roles, both as protection

against tidal waves and for fisheries and salt manufacturing. The beaches and

tidelands provided the vital environmental functions of aeration, water purification, and maintenance of the ecological balance for birds and shellfish,

while at the same time affording recreational and sightseeing opportunities

for people to swim, fish, and surf.

However, as land reclamation and harbor facility construction increased

during the period of Japan's high economic growth, the beaches and tidelands

gradually disappeared along the shores of the large urban areas. Today only

10 percent of the original beach areas remain around the shores of Tokyo Bay.

Now that industrial development has peaked, the importance of these beach

areas is being reevaluated. The needs of the people have diversified and

their interest In the natural environment has increased.

Under these social circumstances, the Ministry of Transport began a study

of methods to dispose of, or utilize, dredged material generated from sea bottom management and port and harbor work. Dredged material disposal and utilization can be placed in the overall sea environment improvement scheme as

illustrated in Figure 1. Actual examples of the use of dredged material for

bepch reclamation are presented in the following paragraphs.

92-17629 8

I IIMI 111I!111 IIII!IIII!111111 Iii! 1I1
Bottom sedim n t Lion rort and larb r

clarification - - - works

Dredged material disposal

erig Dredging and uilizaion Fairwa and

cI v anchorage

Sea Boton Caidredge

improveent a SaBd beach na a i nBathing wcoestruction area 

Biochore improve

ment for marin

life sa

Fish biochore b~e ioc hor Shel fis T-i d l n

"Icollecting areal 1 construction

I, I -_j

Wterfowl biochoreI Wild bird park

Figure 2. Utilization of dredged material for marine environment improvement

Sea Bottom Sediment Clarification Prodects and Beach Reclamation

In bays and inland sea areas where there is ltttle exchange of water between the open sea, huge amounts of organic sediment are created by residential and industrial wastes. This sediment accumulates on the sea bottom, as

illustrated in Figure 2 and Table 1. 9n a sea of this nature, oxygen

Tokyos Bayay

• O •4 ml

[]COD•30 was

Figue 2 Orgnicsedmentdlsrlbt~on(CO = cemial xyge deand

depltiondueto utl ofeutophi sats ad dcompsiton o orani mate

rias wterquaitydegadtio, acelrats terey sverly amaingth

Fisingur 2nusr. Organicveofteoto dsrbto(CD sediment chmclaroxygten demand)
TABLE 1. ORGANIC SEDIMENT STATUS IN TYPICAL SEA ZONES

Environmental Factor Tokyo Bay Mikawa Bay Osaka Bay

Amount of organic sediment,

m3 x 103

COD contamination Ž 30 mg/g 235,000 79,000 226,000

COD contamination Ž 20 mg/g 403,000 240,000 698,000

Area of organic sediment, km2

COD contamination Ž 30 mg/g 440 250 670

COD contamination Ž 20 mg/g 610 320 1,130

Average organic sediment

thickness, cn.

COD contamination Ž 30 mg/g 53 32 34

COD contamination e 20 mg/g 66 75 62

Average water depth in

contaminated area, m

COD contamination 2 30 mg/g 18 11 18

COD contamination 2 20 mg/g 20 10 21

Maximum water depth in

contaminated area, m

COD contamination Ž 20 mg/g 32 18 45

Sediment quality, COD maximum

contamination, mg/g 62 64 45

Sea zone area, km 2 1,200 600 1,500

Amount of seawater, km 3 15 6 42

Average water depth, m 15 10 28

Land water inflow,

m3 /day x 107 3.2 0.7 5.9

is to improve the seawater either by dredging the sediments or capping. Bottom sediment clarification projects have been studied since 1979 (Figure 3).

Bottom sediment clarification projects are broadly divided into the dredging

method and the capping method. The most difficult problem encountered in

dredging projects is the disposal of the large amounts of sand and organic

sediment generated. Table 2 lists the various disposal methods presently

under study, together with their relative advantages and disadvantages. Further details of the beach reclamation disposal method are discussed herein.

10
Study of actual condition of widely polluted Obtaining environarea mental characteris-

• Survey of water quality, sediment tics of the water

quality, etc.

* Analysis of pollution mechanism

Study of estimating environmental improvement effect

" Drvelopment of effect prediction simulation Obtaining long-term

* ofvroutok ~ ~~ ~ ytm Coprio ~ ~ _ 

mod;el effects

" Analysis of settling condition ct clarfation std "• Estimate calculations etc. Evaluatios o

Follow-up field investigation v

th vane stechni a pObtraining loca i

•Poststudy Work program o

Analysis of effects, u etc. to h e pr b em s a b ces pa e rt o f

br management

Work under various conditions

t Study of monitoring work i Identification of

the best work b

method

Development of work method •Dredging and capping method

•Comparison of various work systems

Figure 3. Process of bottom sediment clarification study

The amount of sand and organic sediment produced by dredging is generally

very large, usually very soft soil with a hogh water content. Figure 4 shows

the technical problems in constructing reclaimed beaches with dredged material. Various studies of these problems have been conducted; as a part of

these studies, it was assumed that 3,000,000 m3 of sediment in Osaka Bay is to

be dredged and used to create a reclaimed beachr Figure 5 shows a cross section of the reclaimed beach. By using Table 3, an estimate of the construction cost can be calculated and compared with the costs of other disposal

methods. As indicated in the table, the cost to reclaim a beach is higher

than that of disposing the sediment in pits in the sea bottom or in the open

oceanr However, beach reclamation Is worthy of consideration because no sea

bottom pit exists of adequate size for 3,000,000 m3 of sediment in Osaka Bay,

and it would be difficult to obtain public approval to dispose the material in

the open ocean. Therefore, although the cost of beach reclamation with the

sediment may be high, the cost of reclaiming land by any other means is much

higher.

Port and Harbor Works

and Beach Reclamation

In recent years, the production of dredged material from port and harbor

works has risen to 70,000,000 m3, most of which has been disposed of as land

reclamation materials. It is often difficult, however, to find locations

where such large amounts of material can be placed; and some programs for the

improvement of fairways and anchorages are being delayed for this very reason.

The characteristics of the dredged material for which destinations cannot

be found are suitable for the construction of beaches and tidelands. The

amount of suitable materials is estimated at 2,500,000 m3 per year.

11
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Premses equied cnditonsProblems to Prem ses equi ed c ndit onsbe studied

Disposal site area stbilt t 1. Earth and water

location tyipressure on

revetment

S• ! Sediment removal

Very soft mud _jm'o

sediment at High disposal racteristic of dissea bottom efficiency posed sediment

disposal [eration method

I __• Revetment

SWatertight structure

posed soil surface

laver

__sediment out- disposed sediflow ment iSurface laver

I processing

Saond Stability against ] Sand covering

llittoral drift and, et |scour I m~o

beach Beach thickness

recamation IPrevention of

•eutrophic sub- -

s t a n c e e l u t i o n M e s r a g i t

exchange --- &Remva o

temporary fever-sou

r ent

F~gure 4. Flowchart of beach reclamation technical problems

13
Backshore Foreshore Nearshore

I !

I 150 .

15 135 m

+3.10 msjs s Submerged

2. ' / H.W.L +1.60

Crushed stones 6.0 VM.W.L +0.95 ""+0.00 m L.W.L +0.00

San

X ~2.O0e

\ ~~Organic".•

sediment WU

0u

Cross Organic " X 

w V' revetment sediment

E

Existing ground

Figure 5. Cross section of reclaimed beach

TABLE 3. COMPARISON OF DISPOSAL COSTS

Method Requirements Cost

Land reclamation Peripheral revetment Several hundreds of billion

Surface treatment yen (depending on reEarth cover quired foundation

Foundation improvement improvement)

Beach reclamation Peripheral revetment and 13 billion yen (85% for

cross revetment revetment)

Surface treatment.

Sand covering

Foundation improvement

Sea bottom pit Turbidity prevention work 1.7 billion yen

fill Sheet work

Covering work

Open ocean Transport 81 nautical 1.6 billion yen

disposal miles (150 km) to

open ocean and

dispose

Based on these considerations, beach reclamation studies were initiated.

As such, a large, experimental, artificial tideland construction program was

undertaken at the Ninoshima-Nagahama district, Hiroshima Bay. In this project, 1,300,000 m3 of material produced from dredging the fairways and anchorages of Hiroshima Bay will be spread on 40,000 m of seabed to create a

tideland.

14
This project, which began in 1983 and is currently ongoing, includes construction of submerged breakwaters and the earth covering works. It will

cover a period of 3 years at a total cost of 2.5 billion yen. The unit cost

incurred for the disposal is 1,200 yen/m3 , which can be regarded as reasonable

when compared with the unit cost for conventional land reclamation at

1,000 yen/m3 . The project outline and photographs of the construction work

are provided in Figures 6-10.

Kurahash(j Le

/ Higashinomijima --- National

0 Hiashiomijma Z- N t ina h ighway -- Main local highway

Railway

-------Proposed highway route

ft •Shinkansen

0 1 2 3 4 S 10 km

Figure 6. Location map of Ninoshima District reclaimed tideland

CONCLUSIONS

Because lifestyles are more diverse and the public's interest in the

value of the natural environment is enhanced, the various functions of seashore and beach areas are in the process of being reevaluated. With these

trends, beach reclamation projects have dual functions: create a seashore

environment, and facilitate bottom sediment clarification projects and port

and harbor works. It is from these viewpoints that the Ministry of Transport

plans to use dredged material in the reclamation of beaches to improve marine

environments.

15
Figure 7. Sand covering (sand is transferred from

the sand carrier with a grab bucket

and dumped by a crane ship)

Figure 8. Completed sand cover

16
€:ou~lee4 areaapprox. "300 m )

S~Cros8 t'revtme nt

Figure 9. Plan

Crest of submersed S LI - 1/500

braakuicert V 1/250 b a 60,0 m

3.0.

(.+O.0 4) 0.5 a 1:,0 -2.0 vs

Organic Covr @and

Stsbwrz~d ediment

Figure 10. Standard cross section

17
RESEARCH CONSIDERATIONS OF PHYSICAL FACTORS RELEVANT

TO DISPOSAL OF CONTAMINATED DREDGED MATERIAL

Limberlos Vallianos

Coastal Engineering Research Center

US Army Engineer Waterways Experiment Station

PO Box 631

AD-P006 8396 Vicksburg, Mississippi 39180-0631

II111 1111 11 111 11111111II ABSTRACT

The US Army Corps of Engineers is considering the

initiation of five research areas directed toward

improving analytical methods and field monitoring

procedures related to the physical aspects of disposing and confining contaminated dredged material.

These research initiatives are:

a. Evaluation of critical shear stress. Theoretical and mathematical investigations will be conducted to develop the best methodology for calculating

shear stress. Field measurements will be performed to

obtain data sets for verification of theoretical

results.

b. Fate and stability of dredged material disposed in open waters. This research will involve an

ensemble of existing numerical models in developing a

standard application framework for simulating the

hydrodynamic/sediment interactions in offshore and

estuarial environments. Standardized techniques and

equipment will be developed for monitoring open-water

disposal sites.

c. Suitability of material for capping contaminated dredged material. Research will combine integrated field tests and physical and numerical model

investigations to establish a standard methodology for

the design and placement of stable caps under varying

physical, chemical, and biological conditions.

0_ d. Technology for monitoring hopper loads. This

area of research will focus on defining and assembling

new instrumentation systems that integrate such compo-

___ nents as nuclear density probes, draft indicators, and

microprocessors to monitor and measure hopper loads.

e. Open-water disposal site capacity and management. Numerical and physical modeling of successful

disposal sites will determine if greater capacities

can be achieved by alterations in the existing

18
geometries, and if such alteration would result in

stable disposal mounds. In a second phase of research, representative shapes found to produce high

volume and stable mound configurations will be studied

with the goal of establishing general guidance for

disposal site design and management.

INTRODUCTION

The US Army Corps of Engineers Directorate of Civil Works is involved in

virtually every navigation dredging operation performed in the United States.

Dredging is the largest single Item in the Corps' Civil Works operations and

maintenance budget, and amounts to approximately $475 million (US) annually.

Although dredging has always been a primary function of the Corps, the past

10 years have seen significant changes in the nature of that function and its

interaction with others. Environmental concerns, a large increase in the

level of contract dredging, and the oil embargo and its consequences are some

of the national and international trends that have placed unprecedented demands on the Corps' dredging mission. Additionally, the Office of the President has instituted strong initiatives directed at budget deficit reductions,

project cost-sharing with non-Federal interests, user fees, and support for

the deepening of major US ports. These changes and the Administration's policies have created pressures to examine and improve, where possible, the way

dredging operations are planned, executed, and managed. In response, the

Corps of Engineers has, among other measures, continued a dynamic applied

research effort spanning all aspects of dredging and the placement of dredged

material.. The purpose of this paper is to outline five areas of new and/or

expanded research activities that the Corps is considering for near-future

initiation. These are all related to the physical aspects of placing and confining contaminated dredged material in open waters. Specifically, the areas

of research being considered are: (a) evaluation of critical shear stress,

(b) fate and stability of dredged material disposed in open waters, (c) suitability of material for capping contaminated dredged material, (d) technology

for monitoring hopper dredge loads, and (e) open-water disposal site capacity

and management. Each of these research topics is outlined in the following

text of this paper.

EVALUATION OF CRITICAL SHEAR STRESSES

The critical bottom shear stress (threshold shear stress) is a fundamental parameter required in calculation of water circulation and sediment movement. Every method for calculating water flow and sediment transport rate,

from simple desk computations to sophisticated numerical models, requires an

estimate of this pivotal parameter. The importance of an accurate calculation

of the shear stress and associated friction coefficient cannot be overstated

since not only sediment transport, but also the governing momentum and energy

equations for wave transformation and current circulation contain dissipation

contributions expressed in terms of the shear stress. In present engineering

practice, highly simplified calculation procedures are used to estimate the

critical shear. The basic physics of the critical shear stress are not well

understood, and there is no substantive guidance available for its

calculation.

19
For verification of theoretical developments, there are no data sets

available that give reliable measurements of the shear taken under field conditions. In fact, the instruments needed to make such measurements have only

recently become available. These Instruments must be integrated, developed

into a system capable of field deployment, and then used to acquire data under

a variety of wave, current, and bottom conditions.

Work Unit 1: Calculation of Critical Shear

This work unit will entail an intensive theoretical and mathematical investigation to develop a method for calculating the critical bottom shear

stress. Available methods will be critically analyzed and extended, as necessary, to cover the widest range of engineering application. All relevant

field and laboratory data will be presented in three forms: (a) graphical

representation for field use and desk calculation, (b) computer programs for

use on personal computers (PC's), and (c) computer algorithms for adaptation

in numerical models. Reports will be published to provide the full theoretical background as well as to provide guidance for engineering use.

Calculation of the critical shear requires knowledge of the value of the

bottom friction coefficient. The friction coefficient depends on the bottom

roughness of the bed, as well as the sediment characteristics. In dredging

applications, waves and uniform (tidal) currents may coexist. Therefore, the

calculation of the friction factor and shear stress must be valid for oscillatory flow (waves), uniform flow (tide), and the combination of these two

flows. Results obtained for linear monochromatic waves will be extended to

include a more realistic description of waves by incorporating finite amplitude and spectral effects, if necessary.

The final product is aimed toward providing the Corps with a general and

accurate methodology to calculate the critical bottom shear stress under all

anticipated environmental conditions encountered in dredging and dredged material disposal operations. The results of this work unit will be of immediate

benefit to several other areas of interest. For example, an accurate knowledge of the shear stress is required for defining navigable depth in finegrained sediment and evaluating the stability of disposal mounds.

Work Unit 2: Measurement of Shear

Stress and Threshold of Movement

Calculation of sediment movement requires accurate quantitative knowledge

of the shear stress, both at the threshold of movement and in the active

transport condition. Only limited theoretical work has been done on this

subject, and engineering estimation methods for the bed shear and bottom friction coefficient are extremely crude (for example, use of a constant value

Irrespective of actual sediment grain size, water temperature, presence of

both waves and currents, presence of entrained sediment, and varying water

depth; neglect of phase difference between fluid flow and stress; etc.). The

main reason for inadequate understanding of this important parameter is a lack

of field or full-scale laboratory measurements.

20
Recently, instrumentation has become available with which to measure the

shear stress in the field under operational conditions in which dredging

operations take place. A number of measurement methods have been developed

for deeper water applications, and their capabilities can be extended to the

usual dredging environment. Thus, heavy initial developmental costs can be

avoided by assimilating and modifying existing new technology.

This work unit will evaluate modern techniques for measuring the bottom

shear. Techniques to be investigated include the classical velocity distribution method by means of velocity probes and acoustic doppler speed profiler;

direct measurement of Reynolds stresses; and shear plates. The most reliable

and accurate methodology will be selected for obtaining measurements under

typical site conditions. The focus of the work unit will be on technical

aspects of the equipment in order to optimize measurement capabilities and

actual field data collection.

A bottom stress measurement system and related flow measurement devices

will be purchased and modified for nearshore use. After testing, the system

will be deployed to collect data at representative locations. Numerous field

deployments are anticipated in order to collect data for various sediment

types, water depths, wave conditions, water temperatures, etc. It is well

known that the critical stress developed under laboratory conditions (scale,

sediment state, fluid state) is quite different from the stress developed

under field conditions. Therefore, in situ field measurements under the

widest possible range of environmental conditions are required. Due to the

high volume of raw data return from the electronic instrumentation, special

provisions will be necessary to properly collect, transmit, store, format, and

catalog the data for analysis. The raw data will be appropriately annotated

and systematically archived for use in concurrent and subsequent analysis in

Work Unit 1.

The developed instrumentation will also allow measurement of the sediment

shear at specific sites for optimizing dredged material disposal.

FATE AND STABILITY OF DREDGED MATERIAL DISPOSED IN OPEN WATER

Innovative ideas for placement of dredged material require extensive

study before they are adopted for use in the field. At present, the Corps

does not have a widely accepted, standard procedure for applying numerical

models to a project to predict the ultimate fate of the dredged material. The

Corps needs to develop and implement an accepted procedure that will address

the questions concerning the interaction of dredged material and local processes that arise during a dredging project or the life of a dredged material

disposal area. In order to be complete, this procedure must include both

numerical simulation and In situ field monitoring.

Emphasis will be placed on dredged material disposed in oceanic and

estuarine environments. Because these environments are hydrodynamically

dissimilar, separate modeling techniques are required to provide adequate

predictions of sediment transport, and ultimately the fate and stability of

the disposed material. Characteristically, oceanic environments are well

mixed and hydrodynamically dominated by waves and wave current interactions.

Estuaries tend to be stratified, with large temperature and salinity gradients, and are hydrodynamically dominated by tidal and density currents.

21
Tn the ocean, the interaction of dredged material with nearshore (inner

shelf) processes such as waves, currents, varying water depth, and wave refraction will be simulated, while modeling efforts in estuaries will address

the effect on dredged material stability of such variables as current velocity, salinity, water depth, wind-induced mixing, water temperature, and bottom

character. In both environments, the short-term (dredging season) and longterm (years) fate of disposed material will be numerically simulated.

The results of this work unit will allow predictions of long-term sediment transport in open-water disposal sites. This will permit updating characteristics such as material size, quantity, and percent of water column

occupied. Utilizing these and other data, the results of the unified modeling

study will enable Field Operating Agencies (FOA's) to determine if disposal

characteristics will change over time. This will allow FOA's to address

rationally a variety of potential circumstances, such as: does the area

change from nondispersive to dispersive by changing sediment characteristics

or occupying more of the water column due to increased disposal rates.

Field measurement procedures using accurate and cost-effective technology

will be developed and implemented. Field data are needed to determine the

most efficient and economic dredged material disposal methods for different

conditions. Field data are also an essential part for numerical model adjustment and verification.

Work Unit 1: Simulation

Methods for Evaluation of Offshore Disposal of Dredged Material

Numerical models will be used to investigate the response of dredged

material to nearshore (inner shelf) processes. A suite of existing numerical

models will be applied, developing a standard application framework to simulate the interaction of nearshore processes on dredged material disposed in

the offshore region. Modeling technology which has been and Is presently

being developed in other research projects will be used to investigate this

problem. In order to apply the results of the numerical simulations to the

largest number of locations, hypothetical project locations, geometries, sediment characteristics, and incident nearshore processes will initially be simulated. Existing models will be used to hindcast the fate of dredged material

disposed offshore. The effects of waves, currents, varying water depth, wave/

current interaction, and wave refraction on the fate and stability of dredged

material will be simulated. Simulations will be used to hindcast the fate and

stability of existing dredging projects which have been extensively monitored.

Additional field data that may be required will be obtained through Work

Unit 3. In order to adequately determine sediment transport potentials over

the life of a dredged material disposal site, it will be necessary to implement both deterministic and stochastic modeling techniques. A fully deterministic approach would most likely be cost prohibitive. Therefore, a

combination of deterministic and stochastic modeling techniques will be used

to obtain predictions of sediment transport directions and quantities from the

idealized dredged material disposal sites.

22
This work unit will produce a set of numerical models that will provide

sediment transport predictions for project planning and guidelines on the fate

and stability of dredged material.

Work Unit 2: Modeling of

Short-Term Sediment Transport in

Estuarine Open-Water Disposal Areas

In an estuary, dredged material is placed in either a low energy area

where it is supposed to remain or a high energy area where it is dispersed.

An understanding of the mechanisms that determine the stability of a site is

essential to the efficient management of disposal areas. Dredged material

disposal models have been develop.ýd and are presently in use to evaluate the

short-term fate of dredged material associated with the disposal process.

However, further expansion and enhancement of these models are needed to include sediment transport relationships into the numerical codes. The result

will be numerical models that predict the final location of dredged material

placed in estuarine open-water sites. With an understanding of the dynamics

of a disposal area and the disposal process, decisions can be made regarding

planning goals, resource storage, permanent disposal, or timed dispersal of

dredged material.

This unit will coordinate with Work Unit 3 to acquire the necessary field

data to modify the existing numerical codes. Case studies of different types

of disposal areas will be conducted in cooperation with participating FOA's.

Work Unit 3: Field Techniques and Data

Analysis to Assess Open-Water Disposal

The Corps presently monitors open-water disposal areas in the oceans,

estuaries, and Great Lakes to ensure that dredged material behaves as planned

and causes no adverse physical effects. The types of monitoring and levels of

detail are presently decided on a case-by-case basis. A task initiated under

the Dredging Operations Technical Support (DOTS) Program is assembling stateof-the-art guidelines for monitoring disposal sites. This work unit will provide the necessary expansion and follow-up to the DOTS task to apply and improve the recommended techniques and equipment and to develop new ones where

the DOTS work identified deficiencies. The work unit will:

a. Apply state-of-the-art techniques at selected disposal sites.

b. Apply new techniques to determine their potential.

c. Recommend methodology or equipment modification or development.

d. Recommend data analysis and interpretation procedures.

e. Tailor the general monitoring guidelines developed under the DOTS

Program for different disposal configurations.

f. Develop data sets for use in Work Units 1 and 2.

23
•. Develop additional data sets to verify models at a range of test

sites.

The case studies of different types of disposal areas will be constructed

in cooperation with participating Corps FOA's.

SUITABILITY OF MATERIAL FOR CAPPING CONTAMINATED DREDGED MATERIAL

Isolation of contaminated dredged material by subaqueous contained aquatic disposal (CAD) in open water is a viable option for many locations. A

considerable body of work exists on designing caps for CAD sites to meet chemical and biological criteria, but considerably less methodology is available

to allow confident prediction of cap physical stability. Stability should be

addressable both from the event (storm) standpoint and from the long-term

perspective.

Work under this task will combine integrated field and laboratory experiments and numerical simulation studies to determine stability of CAD cap materials under varying physical, chemical, and biological conditions. Field

investigations will be performed to gather data for calibrating and verifying

numerical simulation techniques and to obtain representative cap material

samples for laboratory experiments. Flume tests will be conducted to determine high-stress (storm) effects on various types and conditions of cap material. Numerical simulation will include the following:

a. Turbulence closure simulation of a CAD site to approximate the bottom

boundary layer under combined current-wave interaction.

b. Demonstration of simulation techniques to assess the long-term behavior of a CAD cap.

c. Parametric study to establish guidelines for cap placement as a function of bathymetry and expected hydrodynamic conditions.

This work will produce an integrated methodology to both predict the

physical behavior of a CAD cap under particular event conditions and assess

its long-term stability in a given environment.

TECHNOLOGY FOR MONITORING HOPPER LOADS

Vertical density gradients within the sediments collected in the bins of

hopper dredges and dump scows vary depending upon such factors as type and

size of dredging device used, sediment characteristics, retention time in

bins, overflow conditions, and loading cycles. Clamshell dredged material,

especially of new work, is frequently in the form of large cohesive clumps,

while hydraulically dredged material is usually dispersed throughout the

hoppers. The volumetric quantity of dredged material in the hopper is

presently estimated using the displacement method. The change in vessel

draft, the depth (or volume) of material in the bins, some value for specific

gravity, or an estimate of water content of the sediments are influencing

factors to the final calculation of cubic yards of solids in the hopper.

Scientific techniques can be utilized to describe more accurately the

density strata within the hoppers, thus enabling exact calculations of cubic

24
yards of material dredged. The primary function of this work is to define and

assemble new systems that integrate such components as nuclear density probes,

draft indicators, and microprocessors to monitor and measure hopper loads.

A major benefit of this program will be to determine more accurately how

much material has been placed in the hopper and the amount spilled in the

overflow process. Improvements will also be realized in the hopper dredge

economic loading procedure.

OPEN-WATER DISPOSAL SITE CAPACITY AND MANAGEMENT

Selection of open-water disposal sites involves the careful analysis of

many factors such as location, environmental effects, and long-term fates.

Much progress has been made in providing managers with effective and functional design guidance on site selection. However, after a suitable site has

been selected, a determination of site capacity is made using somewhat limited

technology. If the engineer's estimate of disposal site capacity is low, the

result might be the abandoning of the site before it has reached its full

capacity, which may result in disposal activities being shifted to a less desirable location, often at a greatly increased expense. If the engineer estimates a capacity greater than the site should contain, then the overfilling of

the site may cause undesirable effects such as large amounts of sediment being

resuspended or moved out of the immediate disposal area. Placement of material within the area often follows no overall plan, resulting often in discrete piles or in large accumulations near the boundary closest to the dredge

site.

In years past, when dredging activities were less frequent than today and

when operations costs were not as high, accurate determination of open-water

disposal site capacity was not a strong economic factor. Consequently, little

research was undertaken to address this question. In today's economic climate, it is essential that managers have the technology available to select a

potential disposal site, to determine an appropriate and stable threedimensional shape for the site which gives the maximum capacity, and to specify placement of the material within the site to produce the desired shape and

consolidation to maximize site capacity.

This work aims to provide engineers and managers modern methods for

determining open-water disposal site capacity and to produce guidance on managing the placement of material within the site. The 'esearch direction will

build upon past experience by examining those sites that are considered more

successful than others. A recently completed DOTS management task dealing

with initial considerations on estimating site capacity and documentation of

deficiencies with existing methods will form a basis for this work. Postconstruction surveys of these sites will help to isolate potential geometries

which hold promise for design. The relationship of these configurations to

the regional environmental conditions will be investigated. Naturally occurring bottom features such as linear shoals, reefs, and nearshore bars will be

included as potential disposal site configurations. Numerical and physical

modeling of successful disposal sites will focus on determining if a greater

dispesal capacity exists at these specific sites by the design of more

appropriate disposal geometries. Models also will determine if new geometries

produce a stable mound. Immediate benefits may be realized if some of these

selected sites prove to have a greater capacity than previously thought.

25
In the second phase of this research, representative shapes found to produce high volume, stable mound configurations in the site-specific examples

will be studied with the goal of producing design guidance. It is expected

that some shapes will be successful only in a regional extent, being closely

tied to the prevailing environmental conditions.

The final outcome of this work will be greatly improved guidance for

disposal site design and management. This guidance will be in the form of

manuals which will help the manager match a potential site with an appropriate

shape and placement technique, considering local and regional processes. Prediction of actual site capacities for selected designs will be available in

the form of software fitting into the framework of computer-aided design.

26
AD-P006 897

DEWATERING AND REUSE OF WATER BLOOMS

IN THE LAKE AND THE PORT

Zenya Yoshino, Kazumi Sato, Hiroaki Okajima,

Atushi Kasai

Science University of Tokyo

Kagurazaka 1-3, Shinjuku-ku, Tokyo, Japan, 162

Kanshiro Unakami, Shoji lida, Akira Miyamoto

Tsuchiura City

Shimotakatsu 1-20-35, Tsuchiura-shi, Ibaraki-pre., Japan, 300

Tatsuro Kotake

Nippon-Haisui-Giken Co.

Yurakucho 1-4-1, Tokyo, Japan, 100

Ryuichi Sudo, Mitsumasa Okada

National Institute for Environmental Studies

Yatabe-machi, Tsukuba, Ibaraki-pre., Japan, 305

ABSTRACT

The dewatering process for the recovery and reuse

of bottom sediments and water blooms has been developed over the past several years by the Department of

Chemical Engineering at the Science University of

Tokyo. This paper describes how to introduce and

apply the continuous vacuum precoat filter and how

this filter relates to environmental conservation of

lakes and ports.

The experimental results with fundamental apparatus and pilot plants are described, as well as aspects

of the bottom sediments and water blooms used in both

wet and dry forms.

INTRODUCTION

Water blooms, called AOKO in Japan, have increased in nutritious lakes

and ports such as Lake Kasumigaura and a pond, Teganuma, as shown in Figure 1.

Water blooms tend to accumulate locally as water temperature rises (Figure 2),

such as in the height of summer. Ordinarily these water blooms are dominated

by Microcystis aeruginosa, which are smaller than several microns, as shown in

Figures 3 and 4. Figure 5 shows the present treatment process of water blooms

used by the city of Tsuchlura and the Ministry of Construction. However, the

number of water blooms that are treated is much smaller than the total amount

of M. aeruginosa that can be found during the height of summer. After several

92-17630 27 Ii li IIII f~l lltllll
Autg I 4h. Aug M58

Figure 1. I'roliferntlon of waiter blooms

3aJU9I330 ¶,,i

5.U33 wM'~ A& Nq

.;n

IUO 30 1.0 T

... .. 20

100)

Fi gure 2. Pro(gre~s of prol ifernt ion

A~A'%, r 3134.

al 

t0
F I disposal (Tsuchiura)

(1) Conventional soda-silcate

S1 g dispos.l (the Ministry

* of Constrocti fl

(11) Conventional r t t4 process and ( z .4- continuous- L_.O ý vacuur precoat 60--80 reuse as a filter-aid

filIter -dried

I • waterblooms

(111) A 1 pecially farmland as a fettili-er

designed col- lector and c.o to farmland as a fertilizer

conti nuousvacuum precoat

filter

Figure 5. Dewatering and reuse process of water blooms

days, the untreated water blooms rot and begin to smell (Figure 1). Therefore, the development of a process for dewatering and beneficial use of water

blooms is an urgent problem in Japan.

Theoretical and experimental methods of dewatering and reuse of water

blooms have been investigated for several years in our laboratories and In

Lake Kasumigaura. These methods are discussed herein.

FUNDAMENTAL CONSIDERATIONS

As mentioned above, water blooms are dominated by M. aeruginosa, which

are smaller than several microns (Figure 2) and troublesome to dispose of, as

discussed below. In general, the dewatering characteristics of filtrate

capacity of suspensions may be expressed by Equation 1.

For a gravitational dewatering process such as a sand filter:*

u = (I/A)dV/dt = c

3 /k'(1 - e) 2 (1/S) 2 pgAh/L 5

= E3 /k'(1 - E)4 (x/4) 2 pgAh/L (1)

For a mechanical dewatering process such as pressure filter or vacuum filters:

u = (I/A)dV/dt = E

3 /k'(1 - E)2 (1/S) 2 Ap • gc/v L s

= E3 /k'(1 - E) 4 (x/4) 2 Ap - gc/P - Ls (2)

t/V = (L/K)V + (2/K)V (3)

* See notation at end of paper for explanation of variables.

29
where

K = 2A 2 Apg (1 - mw)/awVP (4)

a = 2A 2 Apg(l - mw)/KwiP

= (1 - e)3/E3 (1/p s)k(O/x) 2

V = AR (0 - mw)/awp (5)

From Equation 3, the following relation can be derived:

V/t + Vm/t = [K(/t) + (Vm/t)2]1/ 2 (6)

Then, as the filtration time t increases, filtration rate V/t -1/2

decreases in proportion to t (Yoshino 1984).

Figure 6 compares the solid-liquid separation capacity of conventional

dewatering processes. The continuous vacuum drum precoat filter (hatched area

in Figure 6) is the most effertive dewatering technique of the conventional

processes (Yoshino 1984).

EXPERIMENTAL APPARATUS AND PROCEDURES

Fundamental experimental tests on the thickening and filtration characteristics of various water blooms from ponds (Shinobazu and Teganuma) and Lake

Kasumigaura were conducted in the laboratory at the Science University of

Tokyo, supported by the Ministry of Education, Japan. These tests employed a

batch testing apparatus using a pressure float (Figure 7), a vacuum test leaf,

and small-scale continuous vacuum filters (Yoshino 1984).

Following the laboratory investigations, field experiments were conducted

at Lake Kasumigaura with the continuous vacuum precoat filters (surface area

of 2 and 5 m2 ) (Figure 8) from July 1983 to October 1986.

Figure 8 outlines the experimental plant used at Lake Kasumigaura: a

water bloom collector (Figure 9) to pump the water blooms out of the water

a continuous pressure float to concentrate the dilute suspension of water

blooms (Figure 10), the continuous vacuum precoat filters as dewaterers (Figures 11 and 12), and a rotary dryer (Figure 13). The collected water blooms

are pu ped to the pressure float 0 and the continuou5 vacuum precoat filters

Z5 in Figure 8).

The thin cake formed on the filter (e.g. diatomite or pearlite for the

filter) is removed by an advancing knife while the filtrate is pumped back

into the lake. The filter cakes are dried natural to return to the farm.

The cakes are sent to the rotary dryers (( 8 and (% in Figure 8) and dried

down to grain particles, which are reused as organic fertilizer.

30
5C

tit

10•* *- 1.

1.0 1

jr 'off ,,• • , •,

Ix .

// ': 4I"IV I"k ,,

• d 1 Tg/K 

0..1 I -y_______

I1'

wd [gill

Figure 6. Solid-liquid separation process

31
7 5

14.

0 C

0

30

15

9 9 L/it

13 2 12 12=

S4J

41~

*~02

16j 16 M16 0

Figure 7. Experimental apparatus of flocculation and pressure flotation

aboratory.0.5 ..

collecter

pressure d float

sand-filter

cont.-vac. filt r 2z recoat E 0o • 46 

filter (5 )

T8I rotary dryer

dryer ', . . - Srotary generator

feed tank ., ..

Figure 8. Experimental plant at Lake Kasumigaura

32
Figure 9. Water bloom collecter

Figure 10. Continuous pressure float

, ©

I:I

Figure 11. Continuous vacuum precoat filter (2 m2 )

33
Figure 12. Continuous vacuum precoat filter (5 m 2)

Figure 13. Rotary dryer and dried water blooms

34
EXPERIMENTAL RESULTS AND CONSIDERATIONS

Dewatering Characteristics

Figure 14 indicates the relation between filtration pressure Ap and

specific resistance a of the water blooms measured by the leaf test. It was

found that water blooms are very difficult to dewater by conventional dewatering processes such as filter press and belt press because of the extremely

high specific resistance and excessive compressibility (Figures 6 and 14).

Recovery of Water Blooms

The experiments confirmed that water blooms can be easily collected by

the specially designed collector shown by Figures 9 and 15.

Filter Capacity

Figure 16 indicates the filtrate capacity of the continuous vacuum

precoat filter facility. It was found that even troublesome water blooms

could be efficiently dewatered. Filtrate capacity was approximately

0.8 m3 /m 2 /hr for the water blooms of 4 g/i solid content, and 0.3 mý/m 2 /hr for

the water blooms of 25 g/i solid content.

Since the slope of the dotted line expressing experimental results is

-1/2, the fundamental equation (7) is applicable to these dewatering

phenomena.

Clarity of Filtrate

Filtrate discharged from the continuous vacuum precoat filter was clear

enough (less than 20 mg/i suspended solids) to be pumped back into the lake

and/or reused as process water.

Moisture Content of Filter Cake

The moisture content of the cake removed from the continuous vacuum

filter was less than 78 percent, and therefore eligible for disposal or reuse

as a fertilizer without any difficulty.

In addition, since the cake was very thin (less than 1.0 nmn), it could be

dewatered until the moisture content reached 40 percent by subsequent solar

drying for I or 2 days (Figure 17).

Drying Characteristics of Filter Cake

Figure 18 indicates the drying characteristics of the wet cake

(75-percent moisture content). It was found that dried water blooms containing a small quantity of diatomite (filter aid) were discharged from the rotary

dryer as grain particles (Figure 18) in the proportion of 0.1-k heavy oil/i of

dried products.

35
Figure 14 is missing.

Not provided to WES.

Figure 15 is missing.

Not provided to WES.

36
3I

10

00

• "'-0

-0--

.- -

SinLu o. Dt oidcn /]COD [ppm]

_in._R__No._Dt otgl poi refilt filtrate

July S127'•85 5.52 405 11.95

0. 2 July 29 '85 4.07 380 13.7 10 3 uly 30 '85 8.02 703 18.1

-@ 4 Aug. 1 '85 9.15 1022 21.2

i(L 26 Sept.13 '85 20.8 1810 21.7

0- 27 Sept.1?'85 32.3 2718 25.5

o 2• Sept,18'85 34.8 3040 31.0

SI - 0.1 0.5 1.0 5 10

fc"Cycle time [m.p.rJ

Figure 16. Filtrate capacity of continuous vacuum precoat filter

for the water blooms of Lake Kasumigaura

37
100

4-j

r 50

0

0

1.4

00 20 4-0 6 80 100

Time (hr)

Figure 17. Dewatering curve of the filter

cake by solar drying

400

300O

200

0

0 60 120 180 240 300 360

[min.]

Figure 18. Dewaterlng the filter cake with a rotary dryer

38
Reuse of Dried Water Blooms

Figures 19 and 20 indicate the results of growing test vegetables such as

Komatsuna using a farm soil and a mixture of farm soil with dried water

blooms. The growth rate with the mixture of farm soil and dried water blooms

was superior beyond comparison. Furthermore, because the dried water blooms

contain more than 3 percent available nitrogen, the material can be reused as

organic fertilizer.

Figure 19. Growth tests using komatsuna in farm soil

Figure 20. Growth tests using komatsuna using a mixture

of farm soil and dried water blooms

39
Recycle of Filter Aid

Because the dried water blooms retain more than 2,000 kcal, they can be

burned without additional fuel (Figure 21). The ashes remaining after combustion can be reused as a filter-aid because the specific resistance a was

nearly equal to the specific resistance of a fresh filter aid as shown by Figures 22 and 23.

Figure 21. Combustion of dried

water blooms (without fuel)

Figure 22. Micrograph of filter Figure 23. Micrograph of filter

aid (diatomite) aid (ashes after

combustion, dried

water blooms)

40
CONCLUSIONS

The following conclusions can be drawn from the experimental results:

a. From the properties and dewatering characteristics of waterablooms,

it was determined that water blooms are very difficult to dewater by

conventional methods because of the extremely high specific resistance and the excessive compressibility.

b. By using the specially designed collector, water blooms in the lake

or ports can be easily collected.

c. The comparative studies performed on a dewatering process found the

continuous vacuum precoat filter to be the most effective.

d. The field experimental investigations at Lake Kasumigaura found the

following:

(1) Troublesome suspensions such as water blooms and bottom sediments can be efficiently dewatered with the continuous vacuum

precoat filter.

(2) The filtrate capacity can be expressed by the following

equation:

S = V/(A • t) 6 K * w/2 t

(3) Filtrate discharged from the continuous vacuum precoat filter

contains suspended solids less than 20 mg/i, clear enough for

pumping back into the lake or reusing as process water.

(4) Moisture content of the cake removed from the continuous vacuum

precoat filter is less than 78 percent, and therefore is eligible for reuse as fertilizer or recycling as filter aid.

(5) Filter cakes can be further dried by using a rotary dryer with a

very low consumption of fuel such as 0.1-t heavy oil/i of dried

water blooms.

e. Growth of vegetables using the dried water blooms revealed an

extremely rapid growth rate as compared with farm soil only.

f. The combustion tests of the dried water blooms that were carried out

because the blooms had more than 2,000 kcal found that spontaneous

combustion continued without any fuel, and the ashes after combustion

could be reused as a filter aid to precoat.

The continuous vacuum precoat filter may be the best method available for

the treatment and reuse of bottom sediments and water blooms, from both a

technical and an environmental viewpoint.

41
ACKNOWLEDGEMENTS

These investigations were largely supported by Grants of the Ministry of

Education, the Ministry of Construction, and the city of Tsuchiura.

REFERENCE

Yoshino, Z.; The 10th US/Japan Experts Meeting (Oct 1984).

BIBLIOGRAPHY

Clean Japan Center; Sai-shingenka gi jutsu, Dassui (1981), supported by the

Ministry of International Trade and Industry, Japan.

Hiraoka, M.; Annual Report of Studies on Sludge Treatment (1980).

Hiraoka, M.; Annual Report of Studies on Sludge Treatment (1981).

Hiraoka, M., and Yoshino, Z.; Odei-Shori-Kogaku (1983, Kodan-sha).

Kagaku Kogaku Kyokai; Dassui-shori Gi jutsu Chosa Hokoku (1981), entrusted

from Tokyo Metro.

Kagaku Kogaku Kyokai; Treatment Process and Apparatus of Sludge (1978 in

Japanese).

Ruth B. F.; Trans. Am. Inst. Chem. Eng., 33, 34 (1937); Ind. Eng. Chem., 25,

76 (1933), 27, 708, 806 (1935); 38, 564 (1956).

Steering Group of Special Project Research on Detection and Control of

Environmental Pollution, Supported by the Ministry of Education, Japan;

Chemical Engineering for Water Pollution Control, Vol. 3 (1979).

Yoshino, Z.; Industrial Water, No. 257, 61 (1980).

Yoshino, Z.; Industrial Water, No. 171, 10 (1972).

Yoshino, Z.; Industrial Water, No. 286, 9 (1982).

Yoshino, Z.; Inter. Chem. Eng., 11, 547 (1971).

Yoshino, Z.; Kagaku Kogaku, 30 205 (1966).

Yoshino, Z.; Kagaku Kogaku, 37, 431 (1973).

Yoshino, Z.; Kagaku Kogaku, 43, 130 (1979).

Yoshino, Z.; Kagaku Kogaku, 45, 89 (1981).

42
NOTATION

A Filtration area cm2 or m2

g Acceleration due to gravity cm/sec 2

gc Conversion factor kg-m/kg.sec 2

k Empirical constant

K Filtration constant m2 /sec

L s Depth of filter medium cm or m

m Weight ratio of dry cake to wet cake --

S Specific surface area cm2/cm 3

Sf Filtrate capacity £/(m2 -hr)

t Filtration time sec or hr

t Filter cycle time min or hr c

u Filtration velocity cm3 /cm 2 /sec

V Volume of filtrate cm3 or m3

V Imaginary filtrate volume corresponding cm3 or m3

m to the filter medium

w Solid content g/L or kg/m3

x Particle size um or cm

c Specific cake resistance cm/g or m/kg

Ah Head cm or m

Ap Filtration pressure kg/cm2

E Porosity

P Viscosity g/cm/sec

p Density g/cm3

Shape factor

43
LAKE SUWA IS BEING RESTORED

Tatsuo Yoshida

A8 8 AD-P(•(6 9E8 Japan Sediments Management Association

II I111111ABSTRACT 111111111 

Lake Suwa is the only lake in our country in

which sediment removal has been conducted consecutively for its restoration. Dredging commenced in

1969 and is still continuing. The total amount of

sediment dredged to date is about 1.6 million m3

(16 years), and the scheduled volume remaining to be

dredged is about 5 million m3 .

Although a considerable amount of material has

been dredged, doubt still exists on whether the sediment removal will result in a restorative effect or

not. Sediment removal, as it affects lake restoration, is our greatest concern. This paper describes

our study of these effects.

HISTORIC BACKGROUND OF POLLUTION

Chemical oxygen demand (COD) concentrations at Lake Suwa's center change

from year to year (Figure 1). Prior to 1960, COD concentrations were about

2 mg/t, making the lake oligotrophic. After 1960 the concentration increased

rapidly and reached maximum values of 9 to 10 mg/i in 1977 and 1978, and then

mg/1

10,

8

6

COD

(0-2 / --..

__-__ Eutrophication

1900 1920 19,40 19*60 19'80 20'00

_ Figure 1. Yearly variation of COD

44
decreased to its present state, about half the maximum value. From this, we

can see that the eutrophication began in 1960 and is an occurrence which

spanned over the last 20 to 25 years.

However, COD data obtained over the last 10 years from Lake Suwa has

indicated a trend toward restoration (Figure 2). A comparison between the COD

mg/k

10

9

8

7

0'

6-

COD 0

4

At Lake Center

2

1975 80 85

Figure 2. Variation of COD over the

last 10 years

concentration of Lake Suwa and Lake Teganuma, where there is no restoration

measure being applied (Figure 3), reveals that COD concentrations at the center of Lake Teganuma are increasing, while the COD concentrations at the center of Lake Suwa are decreasing. This seems to indicate that sediment removal

is having.a positive restorative effect on Lake Suwa.

DREDGING

Dredging, approved by the government as a lake restoration technique, began in 1969. The first stage of the Lake Suwa restoration program involved

dredging that portion of the littoral area less than 2.5 m in depth (Figure 4).

The portion of the littoral zone that was dredged had a total area of

2.5 million m2 and occupied 24 percent of the Lake Suwa total bottom area of

10.4 million m2 . The total quantity of dredged material removed from Lake

Suwa from 1969 to 1981 was approximately 1.4 million m3 .

45
mg/k

12

10.

8

COD 6

4

2

1975 80 85

Figure 3. Variation of COD in Lake

Teganuma over the last

10 years

River Tenreu • 8 ..

25x 10• m

Figure 4. Dredged area of the first stage

46
The fact that the dredging began in the shallow area allows room for

criticism. As Figures 5 and 6 show, the sediment in the shallow areas is

weakly polluted, whereas the deeper areas are strongly polluted.

The dcedging should have started in the deeper areas with the highly

polluted sediment; this might have brought about the beneficial effect of

sediment removal more rapidly than did the dredging of shallow areas.

Figure 5. Plane distribution of total phosphorus (T-P) in

sediment

Distance from Shore

600m 400 2O00

1000

U E

2000

3000 "-•

e-~ ooo - 8.

5000I~

mg/kg

Figure 6. Pollution levels

47
Therefore, for the second stage (dates, ), it was decided to begin

dredging in the most highly polluted section of the remaining area. If the

remaining area is divided into four blocks (Figure 7), the first block is the

worst, with mean concentrations of 7,206 mg/kg T-P and 5,611 mg/kg total

nitrogen (T-N).

Lake Suwa•

3rd Block

T-P 3528 mg/kg

~4t/' -h Block TaN 5402'

T-P 2439 mg/kg

T-N 3456

* 2nd Block

;3!t, !:ý-• . k"'. T-P 3225 Ag/ *. T-P 7206mg/'kt T-N 4989 " •;iI:.-N 5611 " __•

Figure 7. Division of lake area

CHANGE OF SUMMER PEAK

A summer peak is a thermal occurrence in a nonstratified lake caused by

increased material released from sediment resulting from the higher water

temperatures in summer. Consequently, the summer peak can be illustrated as a

diagram having a parameter of water temperatures (Figure 11).

Figure 8 shows the summer peak concentration of T-P for 1973 at the

center of Lake Suwa. The T-P concentration increased from 100 ug/t in March

to a peak concentration of 462 um/£ in August.

As Figure 9 shows, the summer peak in 1982 was much smaller, and the

basic concentration also dropped. The summer peak was 170 vg/1 (September),

the basic concentration was 65 ug/l, and the peak ratio was 2.62.

The irregular valley in August is presumably the result of a cool summer

and an abnormally large rainfall. A comparison of the two peaks in 1973 and

1982 shows a much improved lake water quality. To verify the irregularity of

1982, the summer peak of 1984 is indicated in Figure 10. The same pattern is

evident except for water temperature differences.

Figure 11 clearly shows the significant improvement of water quality from

the viewpoint of summer peak.

48
450

T-P

1973

200

150

100 _ _ _ _ _ _ __ _ _ _ _ _

50-

J F•MA M J j A S 0 N D

Figure 8. T-P summer peak in 1973

49
ljg/9.

200

180

160 S57 (1982) /

VO /

/

T-P 120

100

80 _____

0

60 ,0 0

400

20:

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

Figure 9. T-P surmer peak In 1982

250

200,

150

15 - 1981. / 1'" 1984

T-P 100 - 1982 / \

"/ V

50 -''1982

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

Figure 10. T-P summer peaks in 1982 and 1984

50
joo

500-

•0 °

400-

T-P 3

200-

1973

100-

5 10 15 2'0 2'5 30'

Water Temperature

Figure 11. Summer peak versus water temperature

VARIATION IN PEAK CONCENTRATIONS

As mentioned before, in any Polluted lake a phenomenon of summer peak

occurs. Ticerefore, to restore a lake is to diminish its summer peak. In

Figure 12, the peak concentrations are reviewed over the last 15 years.

It is worthwhile to notice that peak concentrations dropped considerably

after 1979. This means that the effects of sediment removal became apparent

at that time.

The quantity of sediment dredged until 1979 was 1.3 million in3 , which

corresponds to 25 percent of the total amount of sediment to be dredged. This

suggests that the effect of dredging does rnot appear immediately, but begins

to manifest itself after considerable quantities of sediment are removed. At

Lake Suwa, the realization of the effect occurred at a dredged percentage of

25 percent and 10 years (Figure 13).

51
i~g/I

500 2.5 0C 27C

400 A 2 2 "5-C

300-

T25. 25C0 A

200 25 22.C

T- Sept.

100

PDredging 4 Effects of Dredging

1969 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 1985

Figure 12. Yearly variation in peak concentrations

x 10,

2000

1800

1600

1400

". 1200 iooo / _ _ _ _ _ _ __ _ _ _ _ _

4-

0

' 80P 80 S800 / Effects Appear

4i 0

C 600C

C

400

200-

/

0t 7 0 75 80 85 90

1969 Time

Figure 13. Quantities of dredged material

52
VARIATION OF CHLOROPHYLL a CONCENTRATIONS

In the worst year, 1973, the maximum chlorophyll a concentration was

300 mg/m 3 (Figure 14). At that time there was an enormous crop of green algae.

mg/m 3

300

200

1973

C. 1.o

C..) 100

0

J, F MA M JJ A S 0 N D

Figure 14. Sumver peak of chlorophyll a

As Figure 15 shows, the peak concentrations of chlorophyll a in 1982 and

1984 were both about 100 mg/m 3 . This is a significant decrease in chlorophyll a concentrations. From a biological point of view, it is clear that the

lake is being restored.

RELATIONSHIP BETWEEN CHLOROPHYLL a AND COD CONCENTRATIONS

The relationships between chlorophyll a and COD concentrations in Lake

Suwa are indicated in Figure 16.

As Figure 16 shows, the relationship curves are linear with a high

correlation. It is interesting that the curves are changing from a steep

slope to a gentle one, in other words, rotating in a clockwise direction. The

transition of these curves seems to provide evidence for the progress of lake

restoration (Figure 17).

53
mg/rm

3

S100 '; t- o I \ \" 7

CL. I

I o 1982 " 50 50

0 o

1984

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

Figure 15. Variation of chlorophyll a

concentrations

mg/mr3 1973

300 •/ 1977- 1978 Normal Research Laboratory

250/ COD= 0.97+0.052 Chloraphyll a

r= 0.92

200o

o0 1980

S198 }Sediment Management Association 1984

0 0

lO00

50.

0

1 00 i 20 mg/A

0 0A

COD

Figure 16. Relationship between chlorophyll a and

COD concentrations

54
1973

01 7-78

Figure 17. Transition of chloro- -C 198-

phyll a and COD curves 0 (o

COD

MATHEMATICAL APPROACH TO SUMMER PEAK

C

The change in lake water concentrations is represented as follows:

V -Lc = Pr(t)A -cQ(1 at

where

V = water volume of lake

c = lake water concentration (for example, T-P)

t =

Pr = release rates of nutrients (in this case, T-P)

A = bottom area of lake

Q = inf lowing quantities

In this case, we assume that the influx loading is steady and does not

contribute to the change in lake water concentrations against time.

V = H , Equation I can be rewritten as follows:

55
ac +2 c = Pr A Pr

at V V H

ac + EC = Pr (2)

at H

where

C - reciprocal of retention time

H = mean depth of the lake

The solution of Equation 2 is obtained as follows:

-t Pr

Cc- = H cdt + C (3)

The seasonal change in water temperature T can be approximated to the

following parabolic curve.

T = Tmax - 2P" (4)

2Pt = T2 Tmax (5) wher Tmax - Tmin (()

where

Twin 0

T = time from the maximum - 0

temperature in autumn to T T

the minimum temperature

in winter

Figure 18 shows the seasonal variation in water temperature in 1973. The

release rate is strongly dependent on water temperature. From our research

the following equation is obtained:

Pr(t) = Pr(20* C)aeT-20 (6)

a'e = 1.11

56
26

24

22

C 20 1972- 1973

= 18

S16 0

~14

S12

i 10

S8

6 0

00a

0

2 o

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

Figure 18. Water temperature versus time (months) for 1973

From the above two assumptions, Equation 3 can be rewritten as follows:

t 2

Et Pr(200 C) aTmax-20 a 2Pt Et

He A ae e dt (7)

ale 2P ( + 0.11) 2Pt = 1 + (0.11) + (0.11)2 = 21) 2.1

( 2 (t2 \1) -t2 2

+ (0.11)3 2pt 2Pt 2Pt - 0.05218 3.1 Pt

* 0.001363 t4 - 0.00002315 - +... (8) pt2 Pt3

e +t 1 E2t2 + -L3- t 3 + 14 t 4 + (9) e =2+Et+ E 6 24

57
t

2

2PT Et 1 0.05218 C2 + tI

F(t) - a e dt = t+ + ++ Pt -

0.05218c 0.001363 0.05218 C2 t

+ + 100036

Pt 64 Pt2 2Pt

+/0.001363 0.05218 3\ 6

kpt2 6Pt i) +- (10)

where F(t) is a function of time and the reciprocal of retention time. The

solution of Equation 2 becomes as follows:

_ Pr(20°C) .Tmax-20 -C t -Ct C H A F(t)e +Ce

As a boundary condition t = 0 , C = Co , F(0) = 0 , then C - Co

Therefore, we get

CH= [ Tm- 2 OF(t) + Co] e (1I)

This is the equation of the summer peak. From this it can be seen that

the summer peak is caused by the temperature dependence of release rates and

retention time. Here we reform the following equation:

,Tm x-2 ,T ax- 0 2 t 2

Pr(200 C) ATmax-20 = Pr(200C) e Tm-20 t +

-2P--t 2P'-'

t2

.T-20 .2Pt = PR(20 0 C) ae ae

t2

= Pr(t) a2Pt

58
Then, Equation 11 can be rewritten once more as follows:

r~t 2P 1 t

[Prt) ae2Pt F(t) + C et

Material

CO=Ciax -

-/

Basic Concentrations

W t

0

It is worthy of notice that the actual release rates can be calculated

from the form of summer peak observed by using this equation as follows:

Pr(t) C - Coe-£t

I/H ale2Pt F(t)e- t

(Ce't - Co)H

t2

ae2Pt F(t)

Figure 19 shows the measurement of water temperature in 1984. From this

it Is presumed that the maximum temperature would have been 260 C and would

have occurred on 15 August, which is taken as an origin of the diagram.

Tmax = 260 C

Tmin = 40 C (assumed)

PT2 732 = 121 11 day 2 /Cc 2(Tmax - Tmin) -2(26 - 4)

Co = Cmax = 250 Og/L

H = 216 m

59
°C

26 t 20 t&13

24 ts37 t22

S20

= 18

S_ 16

0- 14 •t:69

S12

S-W 10

8\

6

1984 o t .73

2

0

J A S 0

Figure 19. Water temperature measured in 1984

Figure 20 shows the release rates calculated in Table 1. By comparing

the calculated release rates in 1973 and 1984 (Figure 20), it is obvious that

the release rates in 1984 decreased significantly when compared with 1973.

This is caused by sediment removal. Consequently, if dredging is continued,

restoration should progress remarkably, as Figure 21 shows.

CONCLUSIONS

Sediment removal in Lake Suwa has been performed over the past 16 years

and will continue for 20 years or more.

For such long-term dredging it is very important to know how the work

done so far has contributed to restoring the lake. From our study it is clear

that the lake is on a steady path toward restoration. This lends confidence

to the present restoration techniques.

From this study we have learned the importance of the inner loading of

pollutants from sediment. The release rates in Lake Suwa are extraordinarily

high and cause a large summer peak. In such a case, there is no effective

countermeasure other than sediment removal. It is reported with pleasure that

this is being verified in Lake Suwa.

60
mg/m 2/d

30-

25

20 0

Pr(t)

10

5 00

0J A S 0

Figure 20. Calculated release rates

TABLE 1. CALCULATION OF RELEASE RATES

t

2 t2

t F(t) 2Pt C Ce~t Ce t-Co Pr

day day 0C a e g/I Ug/i I mg/m 2 /d

-20 -15.90 1.651 1.188 0.698 169 118.0 -132 18.2

13 14.27 0.698 1.076 1.264 240 303.4 53.4 9.04

37 41.17 5.652 1.804 1.946 196 381.4 131.4 4.6

69 80.22 8.249 2.365 3.460 88 304.5 54.5 0.75

61
500

01973

400

0

S-

- 300 C

C QIw

0

/1984

too 200 / Cl./ /

/

/

/

100 10/

00

10 20 3 mgm/d

Max. Release Rates Pr

Figure 21. Transition of release rates

62
MOVEMENT OF TURBID WATER IN RECLAIMING

H. Kojima, E. Yauchi, M. Gomyoh

Japan Dredging and Reclamation Engineering Association

ABSTRACT

This paper presents experimental investigations

on the hydraulic movement of a turbid water in reclaiming to produce an analytical model'for efficient

spill water treatment. The main findings of the study

are as follows:

a. Land is reclaimed by reciprocation of turbidity currents.

b. Density in the spillway is highest in the

tank independent of initial density.

c. Density in the spillway decreases in the last

stage of the experiment.

d. The turbidity current is divided into several

layers.

INTRODUCTION

When land is reclaimed from the sea with a pump dredger, the spill water

flows into the sea from the pond. However, a suitable treatment for the spill

water is necessary to satisfy environmental controls. Therefore, it is necessary to know the movement of the turbid water in reclaiming, in particular,

the change in density of a spill water before reclamation in order to plan a

spill water treatment.

This paper presents experimental investigations on the hydraulic movement

of turbid water in reclaiming to produce an analytical model for efficient

spill water treatment.

EXPERIMENTAL APPARATUS AND PROCEDURE

The tank used in this test was 4 m long, 0.6 m deep, and 0.5 m wide (Figure 1). One side wall of the tank was a glass wall; the spillway was at one

end opposite a turbidity nozzle. The tests were conducted using an artificial

soil. The spherical particles of the artificial soil were composed of vinyl

chloride having a grain-size distribution curve as shown in Figure 2. Their

specific weight and median size were 1.38 and 14 pm, respectively.

63
Motor

[] Flow Meter

[• Control Valve

Over Fl 1

Percent

finr

100

1 10 100

Particle size (um)

Figure 2. Particle-size distribution

curve

The experiment was conducted with different densities. The nozzle diameter, the turbid discharge, and the water discharge remained constant. The

turbidity nozzle position was set on the water surface, as shown in Figure 1.

The reclamation was judged complete when the turbid water could not advance.

Experimental conditions are listed in Table 1. The turbidity in the pond and

the spillway, the profile of the reclamation, and the velocity profile were

measured. The turbidity was measured at the center of the tank, the spillway,

and the median point of the two, using a turbidimeter (transmissometer type).

TABLE 1. EXPERIMENTAL CONDITION

Run Density(Z) Time Discharge(l/min)

I 4.7 45h 00m 1.0

2 20.1 18h 20m 1.0

64
The reclamation profile was measured with a camera and digitized by a

digitizer. The two-dimensionality of the reclamation profile was confirmed by

a preliminary experiment.

TURBIDITY AND DENSITY

Turbidity is an optical property of a suspension (measured in percent

transmittance or NTUs) different from density (usually measured as suspended

solids (SS) concentration). Miyazaki, Saotome, and Masuda (1978)* indicated

that the turbidity was dependent on the particle size, and finer particles

produced measurements higher in density.

We had previously checked the relationship between turbidity and density.

The result is shown in Figure 3. Consequently, Equation 1 was obtained using

the method of least squares:

CSS = - 8058 + 15.1 x Ctur (ppm) (1)

From then on, we used this SS value which was transformed by using Equation 1.

30

20 0

Suspended

Figure 3. Relationship between soluidsed

turbidity and density (xI0 4ppM)

10. 0

I0 / o,

0 1 2

Turbidity (xlO4ppM)

CHANGE OF DENSITY

Figure 4a shows the result of 5-percent density in the nozzle. The density was first observed at the spillway. The reason is explained in the following paragraphs. As the turbid water flows from the nozzle, it settles

vertically, and then advances toward the spillway as a turbid density current.

This turbidity current reaches the spillway without an increase in its thickness. Furthermore, a part of the turbidity current flows out from the spillway, and the rest returns in the direction of the nozzle. Thus, the turbidity

current has alternate layers. These alternate layers reach the water surface

* Miyazaki, S., Saotome, Y., and Masuda, K. 1978. "Influence of Particle

Diameter on the Measuring of Turbidity," Technical Note of Port and Harbour

Research Institute, Ministry of Transport, No. 284 (in Japanese).

65
2000

-------. X=3.Om

:X=4. On

Density

(ppM)

1000

•o10 04 20 30 40

Time (hour)

a. 5-percent density

2000 S. .:X=2.Om .

-------• X=3.Om

S:X=4.Om

Dens (ppm) i ty V

05 10 15 2

Time (hour)

b. 20-percent density

Figure 4. Change of density versus time

after making a return trip in the tank, finally reading the spillway. In Figure 4a, the density value in the spillway is the highest of the three measuring points from beginning to end in reclaiming. The reason Is considered the

same as above.

Figure 4b is the result of 20-percent density. The time spent in reclamation is a fourth of that for 5 percent because the density was quadruple

that for 5 percent. The movement of the turbid water was again a turbid density current. The turbidity changed only moderately for I hr. Thereafter, it

increased for 5 hr. It then remained almost constant from 5 to 10 hr. After

that, it decreased gradually. The result of 20 percent differs from that of

5 percent as follows. In 5 percent, the least density was observed in the

nozzle side, while it was in the middle position in 20 percent. This is true

because in 5 percent, since almost all of the turbid water from the nozzle

settles, the thick turbid water does not flow on the water surface. On the

other hand, in 20 percent a part of turbidity from the nozzle does flow on the

water surface and settles vertically.

It was found that the progress of the experiment can be divided into

three processes: an early stage of increasing density, a second stage of

remaining constant, and a final stage of decreasing. However, it was not

clearly defined in 5 percent.

66
TURBIDITY SPECTRA

Figure 5 shows the results of the turbidity spectra to investigate the

periodicity of the turbidity movement. In Figure 5a, a spectrum peak exists

at the frequency of 2 x 10 Hz (83 min); hence, the turbidity movement is

very slow in 5 percent. The energy in a high-frequency regime remains almost

constant. Thus, it is thought that movement of a turbidity current in a reclaimed pond is random, with little periodicity.

Figure 5b shows the results at 20 percent. A spectrum peak exists at

9 x 10- 4 Hz (19 min). In a high-frequency regime, the spectrum energy is very

small, and more periodic than 5 percent. I

1I o41 

10• 10

10'0

Fiur05 1

f (HZ) f (Hz)

a. 5 percent b. 20 percent

Figure 5. Turbidity spectra

CHANGE OF RECLAMATION PROFILE

Figure 6a shows the change in reclamation profile at 5 percent. In this

figure, the particle profile is flat in the early stage. The accumulation

forms an incline after 20 hr, and then becomes an acute angle. Further, the

thickness changes only slightly at the 3- or 4-m point near the spillway after

28 hr. When the angle becomes steep, particles accumulate near the nozzle.

Similarly, Figure 6b shows the results at 20 percent. In this figure,

the process of reclamation is similar to a fourth of that in 5 percent. In

67
20

8H48H

40H

S10 32H

424H

8H

04

1 2 3 4

Distance along tank X, m

a. 5 percent

20

10H

i 10. 8H

N 4H

2H

04

01 2 3 4

Distance along tank X, m

b. 20 percent

Figure 6. Change in the reclamation profile

comparison with Figure 4b, it is found that the particles accumulate beyond

the water surface when the density decreases. At this time, few particles

reach the spillway because they stop in the middle of the slope after

slipping.

VELOCITY PROFILE

Figure 7 shows the vertical velocity profile near the glass wall at

20 percent after 100 min. In this figure, it is found that the layer is

divided in 5, and the middle layer is thick, while the layer near the water

surface is thin. The velocity of the return current reaches a maximum near

the water surface. The turbidity current advances strongly on the water surface and on the bed. On the other hand, it returns strongly in the middle

depth zone. This means that the movement of the turbidity current in reclamation is not explained by a settling-basin model or a diffusion-equation model.

The density front of turbidity current just after flow initiation moved at a

rate of 0.92 cm/sec. This velocity is almost equal to the dominant frequency

of the turbidity spectrum because it takes 15 min for this turbidity current

to go and return once.

68
20

o-10

4IJ

04

-02 -0.1 0 01 02 03

Velocity U, cm/s

Figure 7. Vertical velocity profile

(after 100 min)

CONCLUSIONS

The main findings of the present study are as follows:

a. Land is reclaimed by reciprocation of turbidity current.

b. Density in the spillway is highest in the tank independent of initial

density.

c. Density in the spillway decreases in the last stage of the

experiment.

d. The turbidity current is divided into several layers.

69
DREDGED MATERIAL DISPOSAL MANAGEMENT STUDIES FOR THE

PORT OF NEW YORK AND NEW JERSEY: PROGRESS REPORT

J. F. Tavolaro and J. Zammit

AD-- 006 899 US Army Engineer District, New York

Operations Division

26 Federal Plaza

New York, NY 10278-0090

ABSTRACT

Recent progress is presented of ocean disposal

activities and studies of alternatives to ocean disposal for contaminated dredged material from the Port

of New York and New Jersey. The capping studies conducted in 1980-81 and subsequent monitoring have shown

that ocean disposal of dredged material in the New

York Bight can be managed effectively by pin-point

disposal and capping when necessary to mitigate potential adverse environmental impacts. Disposal in subaqueous borrow pits with capping has been determined

to be a technically feasible and environmentally suitable disposal alternative. Environmental clearances

are currently being pursued to designate a borrow pit

disposal site in New York Harbor, to be reserved only

for dredged material not suitable for unrestricted

ocean disposal. Siting studies are still being performed for locating a large containment island, and

three potential sites have been identified in the

Lower Bay of New York. Beach nourishment, upland disposal, use of dredged material as sanitary landfill

-• cover, small containment areas and wetlands stabiliza-

___ tion with dredged material are all possible in special

I • cases on a project-by-project basis but not on a regional basis at this time. The results of these studies have demonstrated there is continued need for

ocean disposal of the majority of dredged material

from the Port, that ocean disposal can be managed

effectively in an environmentally sound manner, and

that there are a few potential disposal alternatives

for the limited volumes of dredged material which are

not suitable for unrestricted ocean disposal.

INTRODUCTION

Among the many duties of Operations Division in the New York District is

facilitating navigation in the Port of New York and New Jersey by dredging the

over 380 km of Federal navigation channels and managing the disposal of the 6

to 7.5 million cubic metres of dredged material generated each year.

70
Historically, 90 percent or more of this material has been disposed each year

in the ocean at the "Mud Dump Site" (see Figure 1). However, because the

majority of the dredged material is predominantly silt and clay and is contaminated to varying degrees with heavy metals, petroleum hydrocarbons, and

organic compounds such as PCB's, studies of alternatives to ocean disposal and

the environmental impacts of ocean disposal were started in 1980.

P46WM TomSI

Figure 1. New York Harbor showing major rivers and

Mud Dump Site

Previous papers presented by other authors at earlier U.S./Japan Conferences described some of these studies of dredged material disposal alternatives and ocean disposal impacts. Studies of "capping" at the Mud Dump Site

and in subaqueous borrow pits were discussed in the 1981 and 1982 conferences

(Suszkowski 1981, Suszkowski and Mansky 1981, Mansky 1982). Studies of alternatives to open water disposal were discussed at the 1983 conference (Coch et

al. 1983). These were the construction of large containment islands, construction of small containment areas or wetlands stabilized areas adjacent to

shore, confined upland disposal, use of dredged material as sanitary landfill

cover, and beach nourishment. This paper will describe the status and results

to date of the studies of each of these disposal alternatives. Although the

study of alternatives to ocean disposal will not be completed until the end of

1987, we have progressed to a point where conclusions have begun to

crystallize.

71
CAPPING STUDIES

Capping at the Mud Dump Site

Capping is the covering over of subaqueous disposed contaminated dredged

material with relatively uncontaminated dredged material in order to isolate

the contaminated material from the marine environment. Previous capping projects have been successfully completed in Hiroshima Bay and at several sites in

the Long Island Sound (O'Connor and O'Connor 1983). Based on the success of

these projects, a capping pilot project was performed at the New York Bight

ocean disposal site in 1980. Approximately 650,000 cu m of contaminated

dredged material was disposed at a previously unused portion of the Mud Dump

Site and capped with 224,000 cu m of relatively uncontaminated fine-grained

dredged material and 1.2 million cubic metres of dredged sand (Suszkowski

1981).

Chemical, geological, and biological monitoring was performed to determine the effectiveness of capping in minimizing the environmental effects of

ocean dumping. A sediment budget study was performed in order to estimate the

amount of contaminated dredged material which could be dispersed into the

environment during the dredging and disposal process (Tavolaro 1984). Estimates were made of the dry mass of dredged material before dredging (inplace), during transport (in the barges), and after disposal in the ocean

using a variety of measurement techniques. After disposal, a sediment cap

stability study was performed to estimate the surficial sediment characteristics of the cap over a 1-year period, determine the erosional thresholds of

the cap material using in situ measurements, and measure aspects of the physical oceanography over the Mud Dump Site which affect the stability of the cap

(Freeland et al. 1983). A mussel bioaccumulation study was performed after

capping was completed to determine if caged mussels at the cap site showed

higher levels of bioaccumulation of contaminants of concern than mussels

placed at control sites in the New York Bight (Koepp et al. 1982). Also performed was a geochemical study designed to determine if capped dredging projects could be chemically discerned from the cap material, the degree of variability in sediment chemistry of individual barge loads of a dredging project,

and whether individual dredging projects could be identified after disposal. by

unique chemical signatures (New York University Medical Center 1982). The resuits of all these studies, and an overall review of the effectiveness of the

capping project in the New York Bight, were prepared (O'Connor and O'Connor

1983).

The capping studies conducted in 1980-1981 and subsequent monitoring have

shown that ocean disposal of dredged material in the New York Bight can be

managed effectively by pln-point disposal and capping when necessary to mitigate potential adverse environmental impacts. The chemical, geological, and

biological monitoring performed concluded that:

a. rn--ing can be effectively conducted in the open ocean conditions of

the New York Bight. Through pin-point disposal techniques it is possible to place a 1-m cap of uncontaminated material over contaminated

dredged material.

b. Less than 4 percent (by weight) of the dredged material to be capped

is dispersed during the disposal operation.

72
c. The sand cap is stable under normal weather conditions.

d. The cap is an effective barrier to the migration of metals and

organic compounds from the contaminated dredged material into the

water column.

e. Bioaccumulation of contaminants from the dredged material is not

likely to occur. Mussels placed on the capped deposit showed no

increase in body burden of contaminants above mussels placed at

reference sites.

Since 1983, we have continued to monitor the cap site by periodically

coring through the deposit, noting cap thickness, and chemically analyzing the

sediment layers. This monitoring shows that the cap is still present with no

signs of major loss of cap material and that the cap has continued to be an

effective barrier to contaminant migration. Because capping has proven to be

an effective environmental mitigation technique for dredged material disposal

in the New York Bight, it is used on an operational basis when determined

necessary.

Capping in Subaqueous Borrow Pits

Capping of dredged material in subaqueous borrow pits was also studied as

a separate effort. Subaqueous borrow pits are underwater pits that remain

from sand and gravel mining operations. In the Lower Bay of New York Harbor,

many of these pits occur, and there is the potential that additional borrow

pits would be dredged in future sand mining operations. These existing borrow

pits are acting as sediment "sinks," rapidly accumulating fine-grained sediments in contrast to the surrounding sandy bottom. Also, the dissolved oxygen

concentrations and benthic community assemblages present at certain times of

the year in these borrow pits indicate a highly stressed and variable environment (Bokuniewicz, Cerrato, and Hirschberg 1986). This makes them potentially

very desirable sites for the disposal of highly contaminated dredged material.

At the 1981 conference, a planned pilot project was described involving

the filling of one small portion of an existing borrow pit in a three-phase

operation (Suszkowski and Mansky 1981). However, concern over the environmental impact of the project to fin fish populations led to further studies of

fish distribution in the area and a delay in the pilot project (Pacheco 1983;

National Marine Fisheries Service 1984; Conover, Cerrato, and Bokuniewicz

1985). The fisheries surveys showed that all deepwater, muddy-bottomed areas

in the Lower Bay could be characterized by the same type of fish populations

and that these populations were higher in catch, number of species, and weight

of trawl than populations in shallower, sandy-bottomed areas. Because no

unique fisheries utilization of borrow pits was observed and because there are

many deepwater, muddy-bottomed areas in the Lower Bay, no significant impacts

to overall fish populations were anticipated by filling in a borrow pit.

While these fisheries studies were being performed, the ocean disposal

capping studies described previously, as well as laboratory studies of the

effectiveness of capping, were completed (Brannon et al. 1985). Also, a successful capping operation in a borrow pit in Puget Sound was completed

(Sumeri 1984). The completion of all these studies led us to the conclusion

that disposal of dredged material in a borrow pit with capping is

73
operationally feasible, environmental impacts to fisheries could be minimized

to the point where they were not environmentally significant, and therefore

the small pilot project originally planned was no longer needed.

Efforts were then turned towards designing an operational borrow pit disposal program using either newly dug or existing borrow pits. Separate

screening criteria have been developed to look at the suitability of existing

borrow pits and potential areas to excavate new pits for the disposal of

dredged material (Figure 2). Environmental clearances are currently being

pursued to designate one or more borrow pit disposal sites in New York Harbor.

However, based upon the current sociopolitical climate concerning disposal of

dredged material in the estuarine waters of the New York/New Jersey area, it

is not likely that more than one borrow pit disposal area will be designated

at any time. Because of the limited volume available in a borrow pit, it will

be reserved only for dredged material not suitable for unrestricted ocean disposal, as determined by the ocean disposal testing criteria.

S Brooklyn too

Island

40 qW

New Jersey

Existingj Prpoe Sn Proposed New

Boro PrpoedSnds Borrow Pit

Mining Areas @QLocations

Figure 2. Locations being studied for the potential

siting of a borrow pit disposal site

CONTAINMENT FACILITIES/WETLANDS STABILIZED AREAS

Containment facilities are diked disposal areas located in offshore

shallow waters. As discussed at the 1983 conference, two types of containment

facilities are being studied in the New York Harbor area: large containment

islands of up to 200 ha and small containment areas attached to the shoreline

(Coch et al. 1983). It was also determined to consider the creation of tidal

74
wetlands using dredged material at any site that might be suitable as a small

containment area. Siting criteria were very similar for small containment

areas and wetlands stabilized areas, so the siting studies were combined. The

studies primarily involved locating an environmentally appropriate site for

the facility.

Small Containment Areas/

Wetlands Stabilized Areas

Preliminary siting studies for small containment areas and wetlands stabilized areas involved delineating waterways in the New York Harbor area that

are highly biologically productive and exclude them from further screening (US

Fish and Wildlife Service 1982). Criteria were then developed to screen the

remaining waterways for suitable sites for containment areas and wetlands stabilized areas (Allen 1983), and nine separate sites were identified (US Army

Engineer District (USAED), New York 1983c).

Further site-specific coordination with local civic groups, environmental

groups, and government agencies led to the elimination of sites 1, 3, 6, 7,

and 8, based upon environmental considerations. Four sites remained for further consideration in greater detail, site 2 - Raritan Bay, site 4 - Bowery

Bay, site 5 - Flushing Bay, and site 9 - Newark Bay (Figure 3). A preliminary

engineering and economic analysis of containment area and wetlands stabilized

area construction was performed at each site (Poindexter 1985). A preliminary

benthic faunal survey was performed at each site to estimate the nature of the

benthic community that would be affected if these facilities were built

(Cerrato and Bokuniewicz 1985). Computer modeling was also performed to determine the degree that tidal elevations and tidal currents would be impacted

by containment area or wetlands stabilized area construction (Bokuniewicz,

Bowman, and Visser 1985). In addition, an analysis of potential impacts from

odors, dust, and bird populations was performed by surveying other Corps of

Engineers Districts to determine if these factors had been a problem elsewhere, and if so, the means by which the problems were solved (Shafer 1984,

Landin 1984).

As a result of these studies, it was determined that site 4 - Bowery Bay,

site 5 - Flushing Bay, and site 9 - Newark Bay should no longer be considered

as wetlands stabilized sites. Sites 4 and 5 flank La Guardia Airport, and it

was determined not to be prudent to attract bird populations so close to this

heavily used airport by constructing wetlands. Collisions between birds and

jets have been documented to cause extensive damage to jet engines and in some

cases have caused airline accidents. Site 9 - Newark Bay could not be attached to the shoreline because of the adjacent Port Newark and Elizabeth facility and could only be considered as a small containment island site. Constructing a wetlands island was not considered appropriate due to the port and

industrial facilities surrounding the site.

Site 2 - Raritan Bay is contiguous to undeveloped county parkland which

contains extensive wetland areas. It was therefore determined that this site

should no longer be considered as a containment area site, but only as a wetlands stabilized site, which is more compatible with adjacent land use. No

significant adverse environmental impacts to tidal currents or elevations were

determined for any of the four sites by the computer modeling. Also, no

75
New Jersey

1 Sandy Hook, NJ

2 Raritan Bay. NJ 5

3 Caven Point. NJ 6 7

4 Bowery Bay, NY

5 Flushing Bay, NY

6 Powell Cove, NY

7 Little Bay, NY NewYork

8 Little Neck Bay, NY 9 3

9 Newark Bay, NJ

€==•/•Staten Brooklyn•

Island

New Jersey

E Sites eliminated Remaining sites: Wetlands stabilization sites SContainment area SSmall containment island

Figure 3. Potential small containment area/wetlands

stabilized area sites

significant adverse environmental impacts were expected from odors and dust,

or to overall benthic populations due to the creation of containment areas or

wetlands stabilization areas at any of the four sites.

The results of the engineering and economic analysis determined that retaining dikes were possible to build at each of the four sites. In addition,

capacity of each site, service life, total cost of dike construction, and cost

per cubic metre were estimated for several scenarios: disposal of contaminated dredged material, disposal of uncontaminated dredged material, and wetlands stabilization (Table 1). It should be noted that the cost per cubic

metre does not reflect dredging, transport, and rehandling costs, but only

cost of dike construction divided by site capacity. Actual cost per cubic

metre would be higher.

The overall conclusions reached were that these four sites have a very

limited disposal volume and would be relatively expensive to construct and

76
TABLE 1. SUMMARY OF THE RESULTS OF THE ENGINEERING AND ECONOMIC

ANALYSIS OF POTENTIAL CONTAINMENT AREA AND WETLANDS

STABILIZED AREA SITES (FROM POINDEXTER 1985)

Service

Capacity Life Total Cost Cost/cu m*

Disposal Site million cu m years million $ $

Containment

area

Bowery Bay 1.2-2.8 9-20 3.1 1.13-2.39

Flushing Bay 0.9-2.2 6-16 8.2 3.74-8.75

Newark Bay 3.1-5.2 23-40 18.4 3.56-5.93

Wetland area

Raritan Bay 4.6 13 13.9 2.66

* Cost does not include dredging, transportation, or rehandling costs of

dredged material.

operate. Also, a wetlands stabilized area could only receive uncontaminated

dredged material in order not to distribute contaminants through the food

chain. The disposal of uncontaminated dredged material does not pose the same

types of environmental concerns as contaminated dredged material disposal and

therefore does not warrant such expensive special treatment. For these reasons, small containment areas and wetlands stabilized areas were determined

not to be feasible as regional disposal options but may be possible in special

cases or on a project-specific basis.

Large Containment Islands

Preliminary siting studies for large containment areas were included in a

report by the US Fish and Wildlife Service (1982). Originally, a 400-ha

island or larger was the focus of the survey, and the preliminary screening

concluded that the Lower Bay of New York Harbor was the only waterway large

enough to be able to contain such a large structure. A position paper was

developed by the New York District in conjunction with an accompanying draft

report on the environmental benefits and detriments of siting a large containment island in the Lower Bay (Bokuniewicz 1983). At that time New York District recommended that siting a large (400 ha) containment island should no

longer be pursued in light of the large area of productive subaqueous habitat

that would be eliminated in order to construct one. However, it was decided

that rather than eliminate the disposal alternative altogether, siting studies

should continue for a smaller version of a containment island, i.e., 200 ha.

Also, in order to maximize the use of a smaller containment island, it should

be reserved only for dredged material that could not be disposed in the ocean

without capping and/or for dredged material that did not meet ocean disposal

77
testing criteria. This would reduce the potential volume demand on a containment island from several million cubic metres per year to several hundred

thousand cubic metres per year at a maximum.

Secondary site screening assessed existing benthic and fisheries information in a computer model to identify the least productive areas in the Lower

Bay (Bokuniewicz and Cerrato 1984). Three potential sites were identified:

the Raritan Bay Site, West Bank Site, and East Bank Site (Figure 4). Planning

level cost and site capacity estimates were then performed for three separate

dike construction scenarios for each potential site: sand dikes, rock dikes,

and sheet pile cofferdams (US Army Engineer Waterways Experiment Station

1985). These are summarized in Table 2. Also, a general estimate of the real

estate value of each site was performed looking at several end use scenarios

(Fowler 1985).

SQueens

Brooklyn

East

Bank

• I1• West Bank\"

S~~~Raritan Bay : 7

New Jersey

Figure 4. Potential large containment island sites

Several studies are still in preparation. Site-specific benthic and

fisheries surveys are being performed over a 1-year cycle. Computer modeling

studies are being performed to determine the degree that tidal elevations and

tidal currents would be impacted by containment island construction at these

sites. Also, a study is being performed to determine if effluent control measures are necessary, using samples of dredged material that are representative

of the type of contaminated dredged material proposed for the sites. All

these studies should be completed by August 1987.

The results of all studies so far have shown that it is possible to construct a large containment island ir the Lower Bay of New York Harbor without

unacceptable adverse environmental impacts. It is estimated that a 200-ha

island could be used for 20 to 40 years if it were reserved for dredged material that needed to be capped if ocean disposed, and/or dredged material that

did not meet ocean disposal testing criteria. When the results of the remaining studies have been reviewed, final decisions on possible site selection

will be made.

78
TABLE 2. SUMMARY OF COST AND VOLUME ESTIMATES FOR SEVERAL

DIKE CONSTRUCTION SCENARIOS FOR THREE POTENTIAL

CONTAINMENT ISLAND SITES IN THE LOWER BAY OF

NEW YORK HARBOR

Sand Dike* Rock

Volume/Cost Site A Site B Site C Dike SPC**

Total cost

$ millions 129 160 192 463 265

Treatment costs

$ millions 8.6 8.6 8.6 8.6 8.6

Storage volume

million cu m 5.0 5.0 5.0 17.4 21.6

Unit storage cost

$/cu m

Without treatment 24 31 38 26 13

With treatment

(settling basin) 26 33 39 27 14

* Site A = east bank, site B = west bank, site C = Raritan Bay.

** Sheet pile cofferdam.

UPLAND DISPOSAL/SANITARY LANDFILL COVER

Upland Disposal

Upland disposal facilities are diked upland areas usually located near

the shoreline. As for containment facilities, most of the studies for upland

disposal sites involved locating an environmentally appropriate site. Preliminarv screening identified all undeveloped vacant land greater than 2 ha

within 160 km of New York Harbor (Leslie et al. 1980). Undeveloped land was

divided into three general categories: cropland and pastureland, wetlands,

and barren areas (less than one-third vegetative cover). It was determined

that cropland and pastureland and wetlands should not be included in further

screening because of their high environmental and/or social value in the

highly urbanized greater New York area. This limited further site screening

to 295 barren areas ranging in size from 2 ha to thousands of hectares. General scre-ning criteria were then developed by the states of New York and New

Jersey to be used tr- determine the environmental suitability of each barren

area.

After applying this criterion to each site, 13 potential sites were

Identified to warrant more detailed screening (Coch et al. 1983). A report

was prepared which outlined the site screening process, identified the

K potential F;Ites along with what specific information was known about the

79
sites, and solicited for any further information which would assist in the

site selection process (USAED, New York 1983b). This report was distributed

to owners of the sites; adjacent owners; local, state and Federal government

officials; community groups: and any other potentially interested! or involved

parties. An updated report was also distributed in the same manner when information became available from these sources (USAED, New York 1984).

Public forums were also held at five separate locations near these sites

to provide additional opportunity for public comment. Based on the sitespecific information gathered in this manner and on further developments

arising from detailed site-specific screening, four sites remained in 1984:

N37 (Port Elizabeth), N61 (Belford, N. J.), L13 (IHutchinson River, N. Y.) and

Raritan Center, N. J. (Figure 5). Three separate disposal site sizes were

studied at the Raritan Center site because the actual area available was not

X S37

S42 X

X S45

New York

(/

New York

New Jersey

SL13

'N56/' Xi! 4-

x L5 2

N37Q()' -•N36 X-.

IN30 f

Raritan r "-

N16 Centerj( -

NXa Xv

New Jerey N18 ",Ni N6

X Sites eliminated

A N Y City Dept of Sanitation pilot project (N30)

0 Remaining sites

Figure 5. Potential regional upland disposal sites

80
certain. Site N30 (Fresh Kills) is a special case study being performed by

the New York City Department of Sanitation and will be described later.

Table 3 shows the capacity and cost associated with each upland disposal site.

TABLE 3. UPLAND DISPOSAL SITE CAPACITIES AND COSTS (FROM

MALCOLM PIRNIE, INC. 1986)

Total Cost*

Capacity $/cu m Total Capacity

Site ha 8 km 16 km million cu m

N37

(Port Elizabeth) 42 12.06 12.88 6.5

N61

(Belford, N. J.) 13 6.51 7.35 2.0

L13

(Hutchinson River) 11 26.43 27.27 1.8

Raritan Center, N. J.

Configuration 1 51 5.18 6.12 7.8

Configuration 2 71 5.05 5.87 10.9

Configuration 3 168 4.90 5.69 25.8

* Two representative transport distances were used: 8 and 16 km.

Because of the limited long-term capacity available in the few upland

disposal sites remaining, it was determined that a regional upland disposal

site could be feasible only if the dredged material were removed after dewatering so that the site could be used again. For this reason, the studies

of upland disposal sites were combined with studies of the use of dredged

material as sanitary landfill cover.

Sanitary Landfill Cover

Sanitary landfills are upland disposal sites for normal household refuse.

At the end of each day, recently placed refuse is covered over with clean

earth fill for health reasons (Figure 6). Thicker layers of fill are also

required if portions of the site remain unused for any significant period of

time or for final site closure. Since there is a great demand for this earth

fill, dewatered dredged material was determined to be a potential source of

cover material, and so the general feasibility of the use of dredged material

as sanitary landfill cover was studied. The four upland disposal sites described above were also studied in detail to determine if they were suitable

dewatering areas.

The overall feasibility studies were divided into two phases (Coch et al.

1983). Phase I involved leachate and physical testing of dredged material

which represented the entire range of chemical contamination of dredged

81
DUMPING

BULLDOZING

•INNL

O.6M FINAL EARTH COVER "-•-••=;•

Figure 6. Schematic view of a landfill with the various

operations and arrangement of "garbage cells"

underground

material in the New York Harbor area. The Phase I analysis determined that

all dredged material tested, regardless of the degree of contamination, met

New York and New Jersey state criteria for daily and intermediate landfill

cover. Approximately 70 percent met the criteria for final cover material

(Malcolm Pirnie, Inc. 1982). Phase II originally investigated dewatering

techniques and application of dredged material as landfill cover in two specific landfills, DeKorte Park and Fresh Kills (Malcolm Pirnie, Inc. 1983).

However, due to comments received on the Draft Phase II report, the entire

scope of the study was modified to eliminate studying dredged material as

landfill cover in DeKorte Park and expanded to include more chemical testing

and the use of the upland disposal sites described above as dewatering areas.

Specifically, Phase II studied dewatering techniques in greater detail (thick

lift versus thin lift), methods to reduce costs associated with dewatering, a

comparison of landfill leachate to dredged material leachate, and at the request of the states of New York and New Jersey, additional bulk chemical testing for base neutral organic compounds, additional heavy metals and organic

compounds, and testing of permeability and pH (Malcolm Pirnie, Inc. 1986). In

addition, Site N30 (Fresh Kills) was included due to interest by the New York

City Department of Sanitation in the possibility of using dredged material

from their own marine transfer station dredging projects as cover material for

the Fresh Kills Landfill. Table 4 shows the cost of landfill cover, yearly

capacity of dredged material, and yearly yield of cover material using the

upland sites as dewatering areas.

While Phase II was being performed, two of the upland sites included in

this study were dropped from further consideration. Site L13 (Hutchinson

River) was dropped because the owners of the site sold it to developers whose

planned use of the site was not compatible with dewaterIng of dredged

82
TABLE 4. YIELD AND COST ASSOCIATED WITH USING UPLAND DISPOSAL

SITES AS DEWATERING AREAS FOR DREDGED MATERIAL TO

BE USED AS SANITARY LANDFILL COVER (FROM MALCOLM

PIRNIE, INC. 1986)

Total Cost* Capacity Yield

Site $/cu m cu m/year cu m/year

N30

(Fresh Kills) 21.21 143,000 63,000

N37

(Port Elizabeth) 36.50 259,000 114,000

N61

(Belford, N. J.) 32.59 79,000 34,000

L13

(Hutchinson River) 50.92 70,000 31,000

Raritan Center

Configuration 1 19.06 310,000 135,000

Configuration 2 18.76 432,000 190,000

Configuration 3 18.32 1,023,000 450,000

* Total cost includes cost of dewatering, stockpiling, land acquisition, and

transport to the nearest landfill.

material. The Raritan Center Site was also dropped because detailed investigations showed that the vast majority of the site contained wetlands regulated

under Corps of Engineers jurisdiction, and these wetlands could not be avoided

by simply redefining the study area boundaries. Since one of the original

site screening criteria was that sites containing Corps-regulated wetlands

should not be considered for upland disposal site development unless the wetlands areas could be avoided, the Raritan Center Site was eliminated from further consideration.

The results of these studies have shown that the use of dredged material

as daily, intermediate, and final sanitary landfill cover is technically and

environmentally feasible in the majority of cases if the dredged material is

dewatered before applying to the landfill. The upland disposal sites studied

were determined to be technically feasible to use as dewatering areas, although they are of limited value if used solely as upland disposal sites due

to their limited site capacities. Although use of dredged material as sanitary landfill cover was determined to be technically feasible, at this time

dredged material is not economically competitive with conventional cover material unless the dewatering site is located immediately adjacent to the landfill. This situation exists only for the New York City Department of

Sanitation at this time, who not only have a dewatering area adjacent to a

sanitary landfill but also generate dredged material from their marine transfer stations. Site N30 is the location of their dewatering area and adjacent

83
sanitary landfill (see Figure 6). They are currently beginning a pilot project using their own dredged material as sanitary landfill cover, building upon

the results of the Corps' feasibility studies. Overall, the use of dredged

material as sanitary landfill cover was determined to be possible in special

cases, but not feasible as a regional disposal alternative for dredged material at this time.

BEACH NOURISHMENT

Beach nourishment is a common practice in the United States in which

dredged sand is placed on recreational beaches to replace the sand lost by

erosion. It is generally performed by hydraulically pumping the sand from an

offshore borrow area. Beach nourishment, in this case, means using sand

dredged from Federal navigation channels to replenish the eroding beaches.

Beach nourishment is usually technically feasible if the dredged material is

approximately 90-percent sand or greater.

A grain-size survey of the Federal navigation channels revealed that only

a relatively few channels contain dredged material that is predominantly sand,

amounting to no more than approximately 10 percent of the average annual quantity of dredged material generated from the Port of New York and New Jersey

(Figure 7). The sand that is dredged from these channels is usually finer

grained than that optimally desired for beach nourishment. Also, the cost of

placing sand from these channels to nearby recreational beaches would be approximately $2.60 to $3.90/cu m above the cost of ocean disposal (USAED, New

York 1983a). From a cost and technical perspective, beach nourishment using

sand dredged from these navigation channels is environmentally acceptable but

is not always the most efficient use of the money involved. At times, it may

be more practical to use this money to dredge sand from an offshore borrow

area where there is more choice available in the quality of sand. There are

also certain limitations placed upon Corps of Engineers involvement in beach

nourishment where navigation projects are the source of sand. Public

Law 94-587, passed in 1976, states that sand generated from Federally authorized navigation projects can be placed on beaches only when it is in the public interest and if the increased cost of beach nourishment over the most

cost-effective method of disposal is paid for by the local interests who

desire the sand. This law was recently modified so that local interests are

only responsible for contributing 50 percent of the increased costs of beach

nourishment. However, even a 50-percent contribution can add up to a significant sum of money for governments to account for.

Because of these factors, beach nourishment using sand dredged from navigation channels is possible only in special cases. Beneficial use of this

sand is still potentially possible and encouraged whenever feasible. For

example, there is currently a demand for sand as fill and construction aggregate material that exceeds the supply available from upland sources. Private

business concerns are currently performing a form of "sand mining" in some

portions of the sandy entrance channels to New York Harbor to meet this demand. This not only puts the sand to some beneficial use, rather than disposing it in the ocean, but the Federal navigation channel is dredged in the

process at no real cost to the Federal government, the state collects revenue

in the form of royalty fees from the dredging company, and the dredging company makes a profit from sale of the sand.

84
S~ Queens

NewJersey

• ~Staten ,

Island A ..

6,~.,

t%~

Predominantly sand

Figure 7. Federal navigation channels which contain

sand potentially suitable for beach

nourishment

CONCLUS TONS

The results of these studies have demonstrated that:

a. There is a continued need for ocean disposal for the majority of

dredged material from the Port of New York and New Jersey. None of

the alternatives to ocean disposal that were studied, either singly

or in combination, would be able to accommodate all dredged material

generated from the Port of New York and New Jersey for more than a

few years.

b. Ocean disposal can be managed effectively and in an environmentally

sound manner through techniques such as pin-point disposal, capping,

and environmental monitoring.

c. Any alternative to ocean disposal must be able to accept the limited

volumes of dredged material which are not suitable for unrestricted

85
ocean disposal in order to be of any real use to the port. There

appear to be two potential regional disposal alternatives which meet

this criterion. Subaqueous borrow pits could satisfy short-term

needs and a large containment island could satisfy long-term needs.

All other alternatives seem to be possible only in special cases and

could be implemented if specific local cooperation is provided.

REFERENCES

Allen, H. 1983. "Siting of Areas for the Creation of Wetlands from Dredged

Material in New York Harbor," Report to the New York District, US Army Corps

of Engineers, by the US Army Engineer Waterways Experiment Station, Vicksburg,

Miss.

Bokuniewicz, H. 1983. "Large Containment Islands in the Lower Bay of New

York," Draft Report to the New York District, by the State University of New

York, Marine Sciences Research Center.

Bokuniewicz, H., Bowman, M. J., and Visser, A. 1985. "Predicted Changes in

Tidal Conditions Due to Potential Containment Areas in the East River, Newark

Bay and Raritan Bay," Report to the New York District, by the State University

of New York, Marine Sciences Research Center.

Bokuniewicz, H., and Cerrato, R. M. 1984. Progress Report on the Siting of a

Large Containment Island, Prepared for the New York District, by the State

University of New York, Marine Sciences Research Center.

Bokuniewicz, H., Cerrato, R., and Hirschberg, D. 1986. "Studies In the Lower

Bay of New York Harbor Associated with the Burial of Dredged Sediment in Subaqueous Borrow Pits," Special Report 74, Ref. 86-12, State University of New

York, Marine Sciences Research Center.

Brannon, J. M., Hoeppel, R. E., Smith, I., and Gunnison, D. 1985. "Long-Term

Effectiveness of Capping in Isolating Dutch Kills Sediment from Biota and the

Overlying Water," Miscellaneous Paper EL-85-37, US Army Engineer Waterways

Experiment Station, Vicksbuig, Miss.

Cerrato, R. M., and Bokuniewicz, H. 1985. "Benthic Fauna at Four Potential

Containment/Wetlands Stabilization Areas in the New York Harbor Region,"

Report to the New York District, by the State University of New York, Marine

Sciences Research Center.

Coch, C., Tavolaro, J., Krauser, R. and Tischbein, P. 1983. "Alternatives to

Open Water Disposal of Contaminated Dredged Material," Management of Bottom

Sediments Containing Toxic Substances: Proceedings of the 9th U.S./Japan

Experts Meeting, 17-19 Oct. 1983, pp 176-197.

Conover, D., Cerrato, R., and Bokuniewicz, H. 1985. "Effect of Borrow Pits

on the Abundance and Distribution of Fishes in the Lower Bay of New York Harbor," Special Report 64, State University of New York, Marine Sciences

Research Center.

86
Fowler, J. 1985. "Costs for Foundation Conditions for a Large Containment

Island," DOTS Program Report to the New York District, US Army Corps of Engineers, by the US Army Engineer Waterways Experiment Station, Vicksburg, Miss.

Freeland, G. L., Young, R. A., Drapeau, G., and Clarke, T. L. 1983. "Sediment Cap Stability Study, New York Dredged Material Dumpsite," Final Report to

New York District, US Army Corps of Engineers.

Koepp, S. J., Santoro, E., Zimmer, R., Nadeau, J., and Ciascio, L. 1982.

"Bioaccumulation Monitoring in the New York Bight Using the Blue Mussel

MytiZus eduZis," Final Report to the New York District, US Army Corps of

Engineers.

Landin, M. C. 1984. "Potential Impacts to Bird Populations at Adjacent Wetlands," DOTS Program Report to the New York District, US Army Corps of Engineers, by the US Army Engineer Waterways Experiment Station, Vicksburg, Miss.

Leslie, M., Aurand, D., Schultz, D., and Holman, R. 1980. "Disposal of

Dredged Material in the New York District: Volume II, Preliminary Evaluation

of Upland Disposal," MITRE Technical Report MTR-7808, Vol. 2, Report to the

New York District, US Army Corps of Engineers.

Malcolm Pirnie, Inc. 1982. "Feasibility Study for Use of Dredged Material

from NY/NJ Harbor as Sanitary Landfill Cover; Phase I: Development and Application of Criteria to Sediment Sampling Results," Report to the New York District, US Army Corps of Engineers.

Malcolm Pirnie, Inc. 1983. "Feasibility Study for Use of Dredged Material

from NY/NJ Harbor as Sanitary Landfill Cover; Phase II: Case Studies at Fresh

Kills, NY and DeKorte Park, NJ," Draft Report to the New York District, US

Army Corps of Engineers.

Malcolm Pirnie, Inc. 1986. "Feasibility Study for Use of Dredged Material

from NY/NJ Harbor as Sanitary Landfill Cover; Phase 2: Evaluation of Dewatering Sites, Upland Disposal Sites and Sanitary Landfills," 2 Vols, Report to

the New York District, US Army Corps of Engineers.

Mansky, J. M. 1982. "Capping of Dredged Material Disposal Management for New

York Harbor," Management of Bottom Sediments Containing Toxic Substances:

Proceedings of the 8th U.S./Japan Experts Meeting, 8-10 Nov. 1982, pp 78-93.

National Marine Fisheries Service. 1984. "Seasonal Occurrence of Finfish and

Larger Invertebrates at Eight Locations in Lower and Sandy Hook Bays, 1982-

1983," Report to New York District, US Army Corps of Engineers.

New York University Medical Center. 1982. "Identifying Chemical Signatures

for Disposed Dredged Materials," Final Report to New York District, US Army

Corps of Engineers.

O'Connor, J. M., and O'Connor, S. G. 1983. "Evaluation of the 1980 Capping

Operations at the Experimental Mud Dump Site, New York Bight Apex," Technical

Report D-83-3, US Army Engineer Waterways Experiment Station, Vicksburg, Miss.

87
Pacheco, A. L. 1983. "Seasonal Occurrence of Finfish and Larger Invertebrates at Three Sites in Lower New York Harbor, 1981-1982," National Marine

Fisheries Service, Report to New York District, US Army Corps of Engineers.

Poindexter, M. E. 1985. "Engineering and Economic Analysis of Potential

Containment/Wetlands Creation Areas in New York Harbor," Report to the New

York District, US Army Corps of Engineers, by the US Army Engineer Waterways

Experiment Station, Vicksburg, Miss.

Shafer, R. A. 1984. "Odor and Dust Impacts at Dredged Material Disposal

Sites," DOTS Program Report to New York District, US Army Corps of Engineers,

by the US Army Engineer Waterways Experiment Station, Vicksburg, Miss.

Sumeri, A. 1984. "Capped In-Water Disposal of Contaminated Dredged Material," Dredging and Dredged Material Disposal, R. L. Montgomery and

J. W. Leach, eds., Vol 2, Proceedings, Conference Dredging '84, American

Society of Civil Engineers, N. Y., pp 644-653.

Suszkowski, D. J. 1981. "Studies on Capping of Contaminated Dredged Material

by the New York District, Corps of Engineers," Management of Bottom Sediments

Containing Toxic Substances: Proceedings of the 7th U.S./Japan Experts Meeting, 2-4 Nov. 1981, pp 134-145.

Suszkowski, D. J., and Mansky, J. M. 1981. "The Disposal of Sediments

Dredged from New York Harbor," Management of Bottom Sediments Containing Toxic

Substances: Proceedings of the 6th U.S./Japan Expercs Meeting, 16-18 Feb.

1981, pp 220-238.

Tavolaro, J. F. 1984. "A Sediment Budget Study of Clamshell Dredging and

Ocean Disposal Activities in the New York Bight," Environmental Geology and

Water Science, Vol 6, No. 3, pp 133-140.

US Army Engineer District, New York. 1983a. "Beach Nourishment as a Disposal

Alternative," New York, N. Y.

US Army Engineer District, New York. 1983b. "Locating Upland Disposal Sites

for Dredged Material," New York, N. Y.

US Army Engineer District, New York. 1983c. "Two Alternatives for the Disposal of Dredged Material; Containment Areas and Wetlands Stabilization," New

York, N. Y.

US Army Engineer District, New York. 1984. "Locating Upland Disposal Sites

for Dredged Material: Progress Report, January 1984," New York, N. Y.

US Army Engineer Waterways Experiment Station. 1985. "Planning Level Cost

Estimates of Dredged Material Containment Islands in New York Harbor," Report

to the New York District, US Army Corps of Engineers.

US Fish and Wildlife Service. 1982. "Assessment of Open Water water and/or

Shoreline Areas in New York Harbor for Disposal of Dredged Material," Report

to the New York District, US Army Corps of Engineers.

88
PREVENTION OF SECONDARY POLLUTION CAUSED BY DREDGING BOTTOM

SEDIMENT CONTAINING MERCURY IN MINAMATA BAY

Yasuyuki Nakayama, Seiki Watanabe, Koichi Kyuma

Environment Department, Kumamoto Prefecture

6-18-1 Suizenji, Kumamoto 862, Japan

Reiichiro Hirota

Aitsu Marine Biological Station, Kumamoto University

Aitsu, Matsushima, Amakusa, Kumamoto 861-61, Japan

Motoo Fujiki

Department of Environmental Medicine

Inscitute of Community Medicine, University of Tsukuba (0

1-1-1 Tennodai, Sakura, Niihari, Ibaraki 305, Japan -

ABSTRACT

In Minamata Bay, sediment containing 25 ppm mercury (about 1,500,000 m3 ) has accumulated on the bottom (about 2,110,000 m2 ), and the fish and shellfish

in Minamata Bay are now polluted by mercury. Since

October 1977, we have been dredging to provide a safe

environment to ensure the inhabitants' health. We

have restored Minamata Bay by dredging a part (about

1,500,000 m2 ) and using the other part (about

600,000 m2 ) as a disposal area.

During dredging, we have guarded against secondary pollution. We have made sure that water quality

did not deteriorate due to stirring of the bottom

sediment or by soakage of mercury from the disposal

area and that marine products were not further pol- (V--

luted. We have established several stations along the CO

border of the working area and measured the concentration of mercury in seawater collected at these sta- ___

tions. The equipment for the analysis is located

onsite so that we can get the results of the analysis •

immediately. If the analysis shows concentration over

the allowed level, we stop or slow down the work at

once and find the cause of the pollution. However,

since the analysis for mercury is slow, we use the

estimation method. This method measures the turbidity

in seawater collected from stations in the work area

for use as indicators of mercury; we then estimated

the diffusion of mercury.

In the first disposal area (dredging was carried

out from June 1981 to March 1984), the estimation

method was used and satisfactory results were

89
obtained. In the second disposal area (dredging began

in October 1982), we are also using the estimation

method for the diffusion of mercury by dredging.

INTRODUCTION

Minamata Bay is a useful port located near the southern tip of Japan and

Port of Minamata in Minamata Bay, which is on the Yatsushiro Sea. Chisso

Chemical Co., located on Minamata Bay, used mercury as a catalyst in making

acetaldehyde and vinyl chloride for the 40 years from 1932 to March 1971. A

part of the mercury used as the catalyst was converted into methyl mercury by

a side reaction in the plant. Methyl mercury in the wastewater discharged

from the Chisso Chemical Co. accumulated in the fish in Minamata Bay, and many

people who ate the polluted fish were poisoned by methyl mercury. It is said

that 70 to 150 tons or more of mercury was discharged to Minamata Bay, polluting most of the bay. The polluted sediment containing mercury at a rate

greater than 25 ppm is 4 m thick at some points In the inner bay.

Mercury concentration in the fish in Minamata Bay has been investigated

for many years. The total mercury concentration of the fish was about 20 ppm

or more (as wet base) in 1960. After the suspension of using mercury in the

Chisso Chemical Co., the total mercury concentration in the fish decreased to

about 1 ppm or less. But this mercury concentration in the fish from Minamata

Bay is higher than that in the fish from other districts, and the total mercury in the same fishes exceeds the safety guideline for fishes (0.4 ppm).

TREATMENT OF SEDIMENT

To solve the mercury problem, we will dredge the sediment which contains

mercury levels higher than 25 ppm (the required level for removal is 25 ppm).

The area of removal is shown in Figure 1, and the working area which includes

the removal area is shown in Figure 2. The inner part of the Bay (582,000 m2 ,

726,000 m3 ) where the bottom has a thick layer of sediment containing the high

concentration of mercury was chosen as a disposal area for the dredged sediment. The area for removal (1,510,000 m2 , 784,000 m3 ) was dredged and pumped

directly to the disposal area.

Most of the mercury in the sediment is thought to be mercury sulfide,

which does not dissolve in seawater. However, the mercury sulfide in the

sediment would transform to methyl mercury under the aerobic condition resulting from the irradiation of sunlight. We decided to use the safe working

method which does not stir the bottom sediments as much. While cleaning the

polluted bay, we have made sure that water quality did not deteriorate due to

stirring of the bay bottom or by mercury soakage from the disposal area, and

that marine products were not further polluted.

First of all, the defense net for fish was set along the border of the

working area to inhibit the movement of fish from the bay to outside or from

outside to the bay. A temporary separation revetment (430 m long) was built

between Koiji Island and Myojin Cape to prevent diffusion of pollutants by

decreased current in the bay working area. Then, at the proposed site of the

disposal area bulkhead, the bottom was covered with a layer of sand I m thick

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to prevent diffusion of the sediment, and the sand-drain work and sandcompaction work were put into operation. After the sand-compaction work, the

bulkhead (762.5 m long) was built by the method of the steel sheet pile cell.

For the dredging, we used the cutterless pump so as not to stir the bottom sediment too much. After the primary sedimentation in the disposal area,

the effluent wcs pumped into the treatment plant and treated with coagulant.

After treatment, the effluent was discharged into the bay. At the disposal

area, the sediment was covered with seawater 0.5 m thick or more during the

dredging in order to inhibit the formation of methyl mercury. After dredging

was completed, seawater on the sediment was discharged into the treatment

plant, and the surface of the sediment in the disposal area was covered with

soil from mountains or sand.

During the dredging in the first working area (experimental dredging work

area), 1980 to 1985, no further pollution caused by the dredging work was

found. Therefore, we used the same work method in the second working area

(main dredging work area). At present, the sand-compaction work, the bulkhead, and the water treatment plant are complete, and the dredging work is

under way in the main working area. All of the work in Minamata Bay is scheduled for completion in March 1990.

MONITORING

As we carried out the work to clean the polluted bay, we monitored the

water and fishes collected from the bay in order to ascertain the level of

environmental pollution caused by stirring the bottom sediment containing mercury; we found no secondary pollution. The monitoring plan is shown in

Tables I and 2. The monitoring stations are shown in Figure 3.

Water Quality

Primary Stations

Several primary stations were established on the border of the working

area to confirm that the water quality outside the working area was not deteriorated by stirring the bottom sediment. If the analysis at these stations

showed concentrations over the allowed level of mercury content, we had to

stop or slow down the work at once and find the cause of the pollution.

In the sample collected from the primary station, total mercury concentration and turbidity were measured three times per day, and pH, COD, DO, and oil

were measured once per day, and arsenic and lead were measured once per week.

Secondary Stations

Several secondary stations were established between the primary stations

and the dredging area in order to estimate changes in water quality and to

determine if a work suspension would be necessary.

Samples collected here (upper, middle, and bottom layer), measured turbidity every 2 hr during the dredging work. We chose water turbidity as the

indicator for mercury content because mercury in Minamata Bay is adsorbed to

the bottom sediment, and we could estimate mercury concentration in water

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using the result from the turbidity measurement. Moreover, the analysis of

mercury takes time, but turbidity can be measured in a short time. Therefore,

a judgment on the suspension of dredging can be made as soon as possible based

on turbidity results.

Before the dredging, the correlation between total mercury concentration

and water turbidity of the bottom sediment collected from Minamata Bay was not

known. The correlation between total mercury concentration and water turbidity was investigated in an experiment in which bottom sediment collected from

Minamata Bay was suspended in seawater (Figure 4). Therefore, turbidity can

be used to monitor for deterioration of the water quality caused by stirring

of the bottom sediment. The allowable level of water turbidity was flexible,

according to the correlation with the mercury concentration in the dredging

area.

Effluent Stations

Effluent monitoring in the disposal area was conducted using the selfregistering analyzer of the continuous system for the water turbidity at the

wastewater treatment plant. We estimated mercury concentration in the effluent by using the turbidity results. Total mercury was measured once per day,

and other pollutants were measured once per week.

Working Area Station

Turbidity and oil at the surface in the dredging area were monitored from

a boat during the work.

Ground-Water Stations

These stations monitored mercury soaking into the ground water. Total

mercury in the ground water was measured once per 3 months. After disposal

was completed, total mercury was measured once per month.

Additional Stations

Supplementary analyses were made for mercury in samples collected from

outside the working area, and for nutritive salts in seawater from inside the

working area.

Marine Products and Plankton

Outside Working Area

Mercury concentration in the fish collected from outside the working area

was measured four times per year. If the total mercury concentration in the

same kinds of fishes averaged 0.4 ppm or more (guideline, 0.4 ppm), methyl

mercury concentration in the fish was measured.

Working Area

In order to determine changes in mercury concentration level in fish,

several kinds of fish were caught using the net, and mercury concentrations

were measured.

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Rearing Test of Fish

In order to know the precise effect (mercury bloaccumulation) of dredging

on the fish as soon as possible, red sea bream and mejina were reared in a

cage in the sea near the dredging work area. Total mercury concentration In

the fish collected in the rearing cage was measured every 10 days.

Plankton

Zooplankton was collected in the working area and outside the working

area every 2 months, and the total mercury concentration in the zooplankton

was measured.

MONITORING RESULTS

Water Quality

Results from the primary stations are as follows:

a. Total mercury. Total mercury in 3,600 to 3,700 samples every year

was measured, and mercury concentration was not detectable in all

samples.

b. Turbidity. Changes in turbidity were caused by rain or red tide.

The change caused the dredging work was not observed. The transition

in monthly average turbidity in the past several years is shown in

Figure 5.

c. Other pollutants. Oil was not detected In any sample. Other pollutants showed the transition caused by natural phenomena, but no

change caused by the dredging work was observed. The results are

shown In Figure 6.

d. Arsenic. The concentration of arsenic was 0 to 0.002 ppm.

The turbidity results at the secondary station are shown in Table 3 and

Figure 5. A change in turbidity caused by rain or red tide was seen, but no

change caused by dredging was observed.

The turbidity changes caused by rain and red tide can be seen in Figure 7. When it rains, large amounts of sediment-laden water stream into the

upper layer of seawater; therefore, the turbidity of the upper layer increases

and the chlorine ion in upper layer decreases. Red tide is formed when phytoplankton and DO in the upper layer increase; phytoplanktons Increase in the

upper layer, which further increases turbidity in the upper layer.

The results from all samples at the effluent station show concentrations

and water turbidity less than the required level.

Total mercury concentrations in all ground-water samples were not detectable, and the transition of chlorine ion was not observed.

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N 00.M0.CD..4C4N CD4 0.-N0-0 C)4N Q 40 4 0. -

04 0414004 N C4 0 ,n04 - - U N 40 4 ! 0 C ,U 0! 04N-4!C)- n 44- 0 

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11 10 14 140 - 4N0a 400 -. 004Q

0ýr . ý0 0 ý1 L Ia!m4 ~ 0, ~ 4 -4N40440--N-00UO!0!-W40Ua.N-U.4-044 w.4-

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00
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-I CY

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-, 103
Marine Products and Plankton

Outside Working Area

Total mercury in all samples was less than the guideline (0.4 ppm).

Working Area

The variation of mercury concentration in fish correlated with the body

length of the fish. A standard body length was selected based on data obtained from each species of fish.

Mercury concentration data in the fish were corrected to the body length,

and the corrected datum (standardized datum) was used in the monitoring

results.

Overall, the effect caused by the dredging was not found or, fish in the

working area (Figure 8).

Fish-Rearing Tests

Rearing tests of fish were carried out every 6 months for 4 years. The

yearly test results were then compared. From the results of these tests, no

effect caused by dredging was found (Figure 9).

Plankton

Monitoring results showed the effect caused by dredging.

CONCLUSIONS

As we dredge Minamata Bay, it is important that water quality not deteriorate because of the stirring of the bottom sediment and the environment not

be polluted. We must monitor for secondary pollution and decide immediately

whether or not to suspend dredging. Therefore, turbidity was chosen as the

indicator for mercury content because the analysis for mercury takes a long

time and we could measure the turbidity in a short time.

Since dredging began, no increase in mercury concentration was detected,

and in the fish-rearing (red sea bream and mejina used), no change was observed in mercury concentration in the fish by bioaccumulation. Also, in the

fish and plankton from the working area, no effect caused by the dredging was

observed.

These results showed that dredging Minamata Bay did not form secondary

pollution of the environment, and the work was carried out very safely.

It can be concluded from this study that the use of turbidity as the

indicator of water quality and the use of fish as the indicator of bioaccumulatioL grasp exactly the effect caused by the dredging work.

At present, the main dredging is under way, and we will continue to follow the monitoring program described herein.

104
* In

41

* 41

0

060

105
0.4

Investigation term

Red sea bream -0- 81. 6 -"81.2 --- 8, 8 B,1 82. S

•) 0.3- ""-- --*- 82,2-83. 62.6 -82.V1r

.4" -- o-- 8J. 6'.8J.Ie

. --- 83.- _]1 - 64.1.1

L41

c - 84. 6- 84.11

uo 0.2-

U

a 0.-

0

0.4

•" oi •.. . •--. ..

0 II I I I I I

0 1 2 3 4 5 6 7

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Investigation term

jHejina a- 8A. l 6-a1.1z -t-- 81.12- A2..r

- &82. 6-82,11

S 03 A- 82.1Z- 83. 1

0 8.,6: 8J.I1

r. - 81. 6- 4.11

U

U

-U0.1

Al'

o 0 1

0 2 3 4 5 6 7

Rearing term ( month

Figure 9. Results of fish-rearing tests

106
- CLEANER SEDIMENTS IN HIROSHIMA BAY--A TRIAL CLEANING PROJECT C

USING SAND COVERING IN KURE INLETHideaki Kakigawa, Kanji Takemura, G•

Kenichi Mizobata, Satoru Shibata -

The 3rd District Port and Harbor Construction BureauMinistry of Transport, Japan

INTRODUCTION G

In recent years, the quality of water and benthic sediments in many of

Japan's enclosed bays has been deteriorating, partly because of the topography

which results in infrequent replacement of bay water with fresh outside seawater, and partly because of the inflow of organic and other objectionable

substances from inland areas. These conditions often cause serious problems

in utilizing the bay as fishery grounds and in maintaining an environmentally

sound bay.

In the mid-1960's, strict regulations were enforced controlling the discharge of pollutants into the sea. At the same time sewage and waste treatment facilities were improved. Thus, the inflowing pollutant loads were reduced; however, this does not mean that bay water quality has been definitely

improved because red tides are still reported very often.

In view of this, the 3rd District Port Construction Bureau, Ministry of

Transport, set up a site to test the sand covering method. The test site is

in Hiroshima Bay (which includes Kure Cove), one of the highly polluted enclosed bays. Sand covering is believed to be one of the best methods for

achieving environmental improvement of sea areas. Its effects are being carefully studied in this experimental project.

This paper introduces the outline of the experimental work implemented

during 1979 and 1980 and its effects on cleaning the bay sediments.

POLLUTION IN HIROSHIMA BAY

As shown in Figure 1, Hiroshima Bay is a sea area surrounded by

Yashirojima Island and Kurahashijima Island. It has an area of 946 km2 , a

volume of 24.2 km3 , and a mean water depth of 25.6 m. Many small islands are

scattered in the bay, and many rivers (the largest being the Ohta River with

flow rates of 100.6 m3/sec in summer and 76.1 m3/sec in winter) flow into the

bay. Thus, pollutant loads generated by the inhabitants and the industries

concentrated in the watersheds of these tributary rivers are carried to the

bay.

The complicated topography of Hiroshima Bay is reflected in its current

flow. The current flows into the bay through Hashirajima Channel, around the

bay clockwise, and out toward Kure Cove when the tide is rising; however,

during ebb tide, the current flows through Kure Cove, around the bay counterclockwise, and out through Hashirajima Channel. The prevailing current, however, comes into the bay through the channel between Hashirajima Island and

107 92-17634 I 11111iilli11111111

II
Ohta

River

N iroshima Seno

Itsukushimal Is land City e e

s.lan•d• Edajima Island

- Experimental Project Site

". Nikawa River

Iwakuni Cit 'Nishi-noa mijima Island

llmazu River-,i! " • "• - . . Ohkurakai , Higashi-Nohmijima Island

Monzen River Is land

0

c~2 VII7Nakaima Island

G,

Yashirojima Island

a 0 5 .0."

Figure 1. Hiroshima Bay area

Kurahashijima Island and flows northward in the bay. In the innermost area of

the bay and in Kure Cove, the prevailing current is comparatively weak and

tends to flow eastward.

The prevailing winds in Kure are from the northeast or north-northeast

and from the west-southwest. Wind velocity is almost always less than 5 m/sec

under normal weather conditions.

Pollution in Hiroshima Bay is discussed in the following paragraphs.

Water Quality

Water quality characteristics of the surface of Hiroshima Bay are indicated in Figure 2 and Table 1. The transparency of the bay water off the

innermost coast is as low as 2 m or less, apparently indicating that the bay

water is very polluted. In this area of low transparency, COD is as high as

3 mg/i, and T-P and T-N are also high, 0.03 mg/1 and 0.4 mg/t, respectively,

and higher concentrations are observed at locations nearer to the innermost

coast.

108
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Z O*- 4 rC'4 -H

0 0

$41

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1094
TABLE 1. SURFACE STRATUM IN WATER QUALITY

Sea Area

Innermost Kure Bay Edajima Kure Entire Area

Characteristic Area Channel Cove Cove Average Range

Transparency, m 2.4 5.9 3.0 4.8 8.3 2.8 - 14.5

pH 8.5 8.2 8.3 8.2 8.3 8.3 - 8.5

DO, mg/i 9.3 6.0 7.1 5.6 8.6 8.0 1 10.0

COD, mg/L 3.4 1.5 2.0 1.4 1.8 1.0 - 3.5

T-N, mg/Z 0.44 0.37 0.37 0.34 0.21 0.14 - 0.39

T-P, mg/Z 0.031 0.035 0.016 0.039 0.018 0.010 - 0.045

Chlorophyll a, 7.9 5.5 1.6 3.7 3.2 0.2 - 23.5

Pglt

Chlorophyll a, the index of primary production, has a concentration not

less than 5 Vg/t in the bay area surrounded by Miyajima Island and NishiNohmijima Island; the concentration tends to become higher at the sites nearer

to the innermost coast, as in the case with nutrient salts.

Benthic Sediments

The conditions of the surface layer of the benthic sediments in Hiroshima

Bay, as indicated in Table 2, show the existence of sediments with high

organic matter content in Edajima Cove and Kure Cove.

TABLE 2. QUALITY OF THE SURFACE LAYER OF SEDIMENTS

Sea Area

Innermost Kure Bay Edajima Kure Entire Area

Characteristic Area Channel Cove Cove Average Range

Ignition loss, % 10 11 12 10 9.6 2.7 ~ 12

COD, mg/g 41 42 55 54 36 3.1 - 62

Sulfide, mg/g 0.28 0.17 0.65 0.82 0.24 0.04 - 0.85

T-P, mg/g 0.67 0.77 0.74 0.79 0.71 0.43 - 0.86

T-N, mg/g 2.2 2.4 2.8 2.8 2.1 0.48 - 2.8

110
To illustrate the distribution of surface layer areas of the sediments

polluted by organic matter, the bay areas with COD of 4 mg/g or more, ignition

loss (IL) of 10 percent or more, and sulfide content of 0.5 mg/g or more are

detailed in Figure 3. The areas with identical pollution conditions are, as

shown in Figure 4, Kure Cove, Edajima Cove, and the innermost coastal water

area of the bay. Pollution is particularly evident in these areas.

Biota

Figure 5 shows the summer plankton levels in Hiroshima Bay. The quantitative distribution of phytoplankton cells indicates that a large number of

cells are produced in Edajima Cove, off the innermost coast of the bay, and in

Kure Cove. No less than 20 species of phytoplankton cells were found off the

innermost coast and in Kure Cove, and no more than 10 species were found in

Edajima Cove. Of the 200 plankton organisms, a total of 56 species were

found, and the average population was 3.5 x 104 organisms/m3 ; the population

tended to increase in the water area around Miyajima Island. In the water

area off the innermost coast of the bay, the species of emerging plankton were

limited, indicating that this water area is less diversified.

The summer distribution of benthic biota in Hiroshima Bay is shown in

Figure 6. While the figure indicates a tendency for the biomass to increase

in the area, the fact that most of the biomass can be accounted for by polychette worms suggests that the bay area is in an advanced stage of organic

contamination.

Red Tide

The number of red tide occurrences in Aki Channel is indicated in Figure 7, and the number of cases where damages were caused by the red tide is

indicated in Table 3. The occurrences are less frequent today than in the

late 1960's; however, approximately 10 occurrences a year are still being

reported.

111
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r. 1

W )

tv'

0)U

4.4

% $4

44 I

3

0

00

-r4

cu C

$4

112
-.- T-S >0.5mg/g

COD Z 40mg/g

* Common

area

Figure 4. Areas where sediments are

polluted by organic matter

113
S.,,0

P • m

• .n f-4

u S0 

....... • ° °•.• •

•,• - . •S......... 

o•

4.• ,i-I

Zq Sn 0

o • ,• • :..o., •. .

,... '. . , •:•,• .-. •,

a ,o•

I].4
N Ohta River

i••• Hiroshima City

Seno River

Itsukushima Island HrsiaCt

Ohtake

River - Nishi-Nohmijima Island

Ose River u

Iwakuni City cit

Monzen River T _aHigashi-No jmijima Island

Kabutojima Island.(J

Kurahashijima Isaland

tMaejima Island 4C)Hashirajima Island

SUki ima F /'Zfakajima Island

Qlsland gen

(Yashirojima CA 200

Island 5

'a-- . Others Unit- Square/0.1 m

-oPolychaete worm

Crustaceans Mollusk

Figure 6. Distribution of benthic biota (Aug 1982)

Figure 7 indicates the monthly distribution of red tide occurrences in

Hiroshima Bay. No red tide occurred in those months not shown in the figure, i.e., January, February, November, and December (survey for the year 1982).

The area in which red tide occurred extended from the innermost coast to

Kure Cove, and red tide occurrences were seen every year in this specific part

of the bay.

BENTHIC SEDIMENT CLEANING PROJECT

As mentioned earlier, environmental pollution has been worsening in

Hiroshima Bay. To alleviate this situation, it is essential that the inflowing pollutant load be reduced and at the same time the self-cleaning ability

of the bay itself be restored. Benthic sediment cleaning was conceived as a

means to break the cycle of nutrient salts and benthic sediment (which serves

as a cyclic medium) and thereby reduce the release rate of nutrient salts. To

be more specific, benthic sediment cleaning removes or covers entrophic sediment deposited at the sea bottom in order to suppress the release of nutrient

salts, prevents oxygen depletion in seawater at the bottom water layer, and

thus restores the self-cleaning ability of the bay area. Before implementation of a full-scale benthic sediment cleaning project, a small-scale

115
o.

0I

C~4 co. , co 0 0

Oi -u

0J ' 0

'.- D~ 0 o t.

04, .. N a.a

di

00

00

000

0.0 WOi

41k 03

01 U Cz o~o .*0

C' C1 3
TABLE 3. RED TIDE OCCURRENCES IN AKI CHANNEL*

1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985

No. of red 11 11 14 24 18 14 18 8 12 8 13 11 14 10 8

tide

occurrences

No. of cases 1 2 4 2 1

where damage

was caused

* After "Environmental Preservation in Seto Inland Sea."

experimental project using the sand covering method was undertaken in

Hiroshima Bay; its effects on environmental improvement are still being studied. This experimental project will be described in the following paragraohs.

Experimental Project

Outline of the project. The outline of this experimental project is

indicated in Table 4.

TABLE 4. HIROSHIMA BAY EXPERIMENTAL PROJECT

1979 1980

Site Off the southeastern of Edajima Island (-21 m)

Project Oct 1979 - Nov 1979 July 1980 - Aug 1980

period

Work Sand covering Sand covering

implemented 1.92 ha (120 m x 160 m) 4.48 ha (200 m x 200 m

+ 80 m x 60 m)

Thickness of sand cover: Thicknss of sand cover:

0.5 m 0.3 m

Ships used Conveyor barge (2,000 m3 ) Unloader ship (260 m3 /hr)

Covering Sea sand Sea sand

material

Project site. The portion of the bay chosen for the site of this experimental project was a tightly enclosed area located off the southeastern coast

of Edajima Island (Figure 8). Pollution was particularly evident 4n this

area. Figure 9 shows the scope and profile of the experimental project.

117
A / \

.° 

"•.~II

Area of the experimental

project (1979 and 1980)

S0

0j2 1000M

50C

Figure 8. Site of the experimental project

273,000

0 Executed Profile 00 in 1980 I I n

i19 Executed Sand Cover

in 1979

208,000 m -165,000 50 cm

Figure 9. Scope and profile of the experimental

project

118
Working method and precision of the work. The work was conducted using

two different methods: one using a conveyor barge, and the other using a

barge unloader (Figure 10). After the work was completed, cylindrical specimens were sampled and measured by the pole penetration method. This measurement indicated that the actual sand covering thickness was 99 to 108 percent

of the design. From this, it may be stated that the design sand thickness was

well satisfied. (Sand taken from the sea bottom about 50 km away from Kure

Cove was used as covering material.)

Follow-Up Surveys of Effects

In order to determine the effects of the experimental project, a series

of follow-up surveys was conducted. These surveys were used to determine how

the release rates of organic substances and nutrient salts from the benthic

sediment were reduced and to what extent the benthic uiota was recovered.

Figure 11 shows the layout of the survey stations.

Benthic sediments and interstitial water. In order to determine changes

in the benthic sediments, COD, T-P, T-N, and SC contents in the benthic sediments and COD, PO4 -P, and NH 4-N contents in the interstitial water were

investigated.

Sea sand transported by gat ship is shipped aboard a barge equipped

with belt conveyor. Sand is then conveyed to the bow equipped with

an extensible tremie through which sand is placed on the sea bottom.

While sand is discharged from the tremie, the conveyor barge is swung

right and left to secure sand cover of a uniform thickness.

covyr BargerTe

Middle lay

a) Method using Conveyor Barge

A box barge to which sand etc. are supplied is brought alongside a

barge unloader ship. Water is jetted into sand in the barge and

slurry consisting of sand-water mixture is pumped into a sprinkler

pipe through which it is discharged into sea water. The barge

unloader ship, acting like a batching plant, moves forward and

backward and also sideways in order to attain a uniform sand cover

thickness.

Bar e unloader ship

Sprinkling pipe

rSprinkling pipe

Gat ship

b) Method using Barge Unloader Ship

Figure 10. Methods used for implementation of

experimental project

119
Area B (Covering sand

placed in July 1980) f Sand cover thickness:

ZZ 30 cm

J Area A (Covering!

Oyster shells and sand placed in Nov 1979) covering sand Sand cover thickness:

50 cm

St2 stl St4

0 0 50 lOOm

St3

Figure 11. Follow-up survey stations located within and outside

of the experimental sand covering project site

Release rates. To determine changes in the release rates of organic substances and nutrient salts (COD, PO4 -P, and NH4 -N) from the benthic sediment,

in situ and laboratory tests were conducted.

Benthos. To determine changes due to the experimental work in the

benthic biota, the species and the population of benthos were investigated.

Survey Results

Benthic sediments and interstitial water. Figure 12 indicates changes in

the benthic sediments in the surface sediment layer sampled from areas within

and outside of the project site. Compared with the benthic sediments sampled

from the area outside the project site, those sampled from the sand-covered

areas (Areas A and B) were characterized by considerably lower contents of

organic substances and nutrient salts. The analysis proved that the effects

of sand covering were well maintained even after a period of about 6 years.

Figure 13 shows the vertical distribution with time of the benthic sediments inside and outside of the experimental project site. At the time of

surveying, a 10-cm-thick layer of loose sediment had accumulated on the sand

cover. Because of this accumulation in the several years after project implementation, the benthos content was somewhat higher than that measured immediately after project execution; however, these values were still lower than

those of the surface sediment layer outside the experimental project site.

The variation of quality of interstitial water in the benthic mud layer

with time is shown in Figure 14. These results showed that the pollutant concentration directly under the sand cover had a tendency to increase with time;

however, all the items (i.e., COD, PO4 -P, and NH4 -N) were maintained at comparatively low levels in the experimental project site.

120
50

40

0 Area A: 50 cm sand covering in Nov. 79

30

S20 S20 Area B: 30 cm sand covering in Aug. 80

Area r outside project site (Average values)

0 S100

Oct. Jan. Apr.July Oct.Jan. Apr.July Oct.Jan. Apr.JulyOct.Jan. Apr.July Oct.Jan. Apr JulyOct. Jan.Apr.July Oct.Jan.

1979 1980 1981 1982 1983 1984 1905

b 1.0

(U r 0.8-

r~U 0. ------------------------------------- • 0.6-. . . . . . .. . . . . . .

2 0.4

0 0.2-

O cC. Jan. Apr.JulyOctJanAprJuly Jan.AprJulyOct. JanApr.J Oct. Jan. Apr. JuJy Oct Jan. Apr. July Oct Jan 19791980 1981 1982 1983 1984 1985

5-

.• 4

En 0.8 ......... . ,---

W 2

0c-

"I Oct. Jan. Apr. July Oct. Jan. Apr.JulyOct. Jan. Apr. July Oct.Jan. Apr. Ju IyOct.Jan. Apr. Ju IyOct. Ian. Apr.,July Oct. Jan.

19791980 1981 1982 1983 1984 198,

oa1.0 or

0.8-

.!0.6-

S0.4-

ov 0.2-

Oct-Jan. Apr.JulyOct. Jan. Apr.JulyOct. Jan. Apr. July Oct.Jan. Apr.Julyact.Jan. Apr.July Oct.Jan. Apr.JulYact. Jan. 19791980 1981 1982 1983 1984 1985

Figure 12. Variation of benthic sediments inside and outside

of the sand-covered site

Release rates. Figure 15 indicates the variation with time (as determined by the in situ test) of the pollutant release rates from the benthic

sediment inside and outside of the sand-covered area. While no obvious effects were recognizable for COD, the effects of sand covering on the reduction

of the release rates were clearly noticeable for the nutrient salts. The release rates in areas outside the sand-covered site were considerably higher

than those inside the sand-covered area. In particular, the sand covering

proved to be remarkably effective for reducing the release rate of P.

121
Area Area A g Outside the site

60

5 0 5................".. o .".......Layer vith lo..se. ud " -- -- - Area A (50-ca sand cover

S" placed in Nov. '79)

Area B (30-cm sand cover SA' ) placed in Aug. '80)

Fxisting layers

50

100-

150

Figure 13. Vertical distribution of

chemical contents in benthic sediments with time

inside and outside of the

sand-covered area

(Sheet 1 of 4)

122
COD T-P T-N T-S

(mg/g) (mg/g) (mg/g) (mg/g)

( 0010 20 30 40 50 0 0. 20. 40. 60. 81.0 0 1 2 3 4 5 0 0. 20. 40. 60. 8 1.0

(c)00 0 0

s0 50 50 -50

100 100 100 100

150- Oct. 79 150 Oct. 79 150 Oct. 79 150 Oct. 79

(pre-project (pre-project (pre-project data) (pre-project data)

data) data)

0 5. 10 20 30 40 . 50 5, 0 0.20.40.60.81.0 50L 0 1 2 3 I. 4 5 50 0.2 0.40.60.81.0 ...

(cm) o5

AO

o0 -?.% - - - -- .... o- 0 ------ o0

50 50 50 50

100 100 100 100

Sept. 80 Sept. 80 Sept. 80 Sept. 80

150 15C 150 150

0 10 20 30 40 50 0 0.2 0.4 0.6 0.8 1.0 0 1 2 3 4 5 0 0.20.40.60.8 1.

(cm) 50 , 1 r= 50 1 1 f s• O -T = 50 1

0 0 0 0 -u

50 50 50 50

100 100 100 10O

Feb. 81 Feb. 81 Feb. 81 Feb. 81

150 !50 150 150

Figure 13. (Sheet 2 of 4)

123
COD T-P T-N T-S

(mg/g) (rg/g) (mg/g) (mg/g) (cm) 0 I0 20 30 40 50 0 0.2 0.40.60.81.0 0 1 2 3 4 5 0 0.2 0.4 0.60.8 1.0

50 Vr-l 5 0- r-1r-r--l 5041rI 7- 50 11--rA .-- I-- -------- ----------- .....-- 

0 A0 ! 0

0

50 50 50 50

10 100 100 100-

150Aug. 81 Aug. 81 Aug. 81 Aug. 81

1o SL150 S

(cm) 0 10 20 30 40 50 0 0.20.40.60.81.0 0 1 2 3 4 5 0 0.2 0.4 0.6 0.81.0

o0 • 50. I-1"- 510... .

~~~~~~ . . ... W -J••:. . . .. . .. S 6

01 -S ----- 5~

I' '. ,i, -i"/

50 Ab 50 50 50 400 I /.

0Y 0

100 / 100 100 J I00

Feb. 82Feb. 82

150 Feb. 82 so Feb. 32 Feb. 82 Fb58

(cm) 0 10 20 30 40 50 0 0.2 0.4 0.6 0.81.0 0 1 2 3 4 5 C 0.2 0.4 0.60.81.0

50 ,150 o30 3 0 0,

"0 -. .0 'A - -0

?• -- ... .. . .-- -,. . * . S%•,,. S. . . " 0 o ----- ,,-- W 'b W. 0.. o . -- A' -'

50 50 50 50

100 100 100 100

Sevt. 82 Sept. 82 Sept. 82 Sept. 82

Figure 13. (Sheet 3 of 4)

124
"COD T-P T-N T-S

(mg/g) (mg/g) (mg/g) (mg/g)

0 10 20 30 40 50 0 0.20.40.6 0.81.0 0 1 2 3 4 5 0 0.20.40.60.81.0

co•~ .... 0. -- --- --

50- 50 - 50 50

0000 100 100

0Feb. 83 1 0 Feb. 83 Feb. 83 Feb. 83

150 150 50 150

0 I0 20 30 40 50 0 0.2 0.4 0.6 0.8 1.0 0 1 2 3 4 5 0 0.2 0.4 0.6 0.8 1.0

60 1 1 60------------60 , 60[7-ý

5030------------------------ 3- o- - -- 50 ---- so........ o

50 50 50 50 -

100 100 100 100

Aug. 185 Aug. '85 A-g. '85 Aug. '85

150 150 ISO 150

0 10 20 30 40 50 0 0.2 0.4 0.6 0.8 1.0 0 1 2 3 4 5 0 O.Z 0.4 0.6 0.8 1.0

60 60 60 60 so ... _ ,: F -- - - SO"5-0" " 50 -- --------------

0 ------ ---------------- 3 ....-- ,30- 

00a- - - 0 ----- 0

50 50 50 50

100 100 100 I00

Feb. '85 Feb. '85 Feb. '85 Feb. '85

150 150 150 150

Figure 13. (Sheet 4 of 4)

125
Area Area

A 8 Outside the Site

60 --- - ' 'Layer with loose mud 50 '- . -. --.. . . .

o j Area A (50-cm sand cover

placed in Nov. '79) )0------------------ -------

5 1 Area B (30-cm sand cover

4 ) placed in Aug. '80)

a ýj /V Existing layers

5O150

Figure 14. Vertical distribution of

quality of interstitial

water in benthic sediment

layer with time inside

and outside of the sandcovered area (Sheet 1 of 4)

126
COD P04-P NH4-N

(mg /Z) (mg/a) (mg/ /)

010 20 30 40 50 0 1 2 3 4 5 0 5 10 15 20 25

-0 - 0 l 0 - I I I -0 --- T

50 50 50

100 100 100

Oct. Oct. Oc t.

1979L 1979 1979

iS5 i5G i50o

0 10 20 30 40 50 01 2 3 4 5 0 5 10 15 20 25

50 q ' 50 I 50 I ,

•- -- ---

50 50 50

IOC 100 100

Sept. 80 Sept. 80 Sept. 80

0 10 20 30 40 50 0 1 2 3 4 5 0 5 10 15 20 25

50 P 50 s I I I 50 '

s o J*..•~ 0 • ...

0 0~ A - ---

50 50 s5o

100 100 100

Feb. 81 Feb. 81 Feb. 81

150 15c 150

Figure 14. (Sheet 2 of 4)

127
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129
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and outside of the experimental sand-covering project

site (in situ test results)

Benthos. Figure 16 shows the variation with time of the number of species and the total population of benthos inside and outside of the sandcovered area. The number of species of benthos and their respective populations in the sand-covered area were larger than those in the outside area, and

130
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although they tended to be lower in summer, they showed a quick recovery in

autumn. From this, it can be assumed that the bioecologic cnvironment was

improved by the sand covering.

SUMMARY

The effects of sand covering in Kure Cove and their sustainability may be

summarized as follows:

a. The concentrations of pollutants in benthic sediments and interstitial water became somewhat higher with time, but as a whole maintained low values.

b. The release rates of pollutants in the benthic sediment in the sandcovering project site were lower than those in areas outside the site.

c. A remarkable recovery of benthos was apparent immediately after

placement of the sand covering. The recovery rate was subsequently

reduced; however, the recovery rate remained more significant than

that found in areas outside the experimental site.

The effects of sand covering on improving the benthic environment, reducing the pollutant release rate, and bringing about the recovery of biota, as

well as sustaining these effects, were generally proven.

In implementing any future benthic sediment cleaning project, accurate

appraisal of the project's effects on improvement of the water quality and the

ecosystem, and studies on measures for preventing Inflow of suspended sediment

will constitute the main problems that will have to be solved. Furthermore,

it is essential that experimental projects of a still larger scale be implemented to develop more effective ways to deal with the actual conditions of

bay area pollution.

132
PUGET SOUND DREDGED DISPOSAL ANALYSIS

F. J. Urabeck, K. E. Phillips

US Army Engineer District, Seattle

PO Box C-3755

Seattle, Washington 98124-2255 AD-P006 902

ABSTRACT

Future disposal of dredged material in the Puget

Sound estuary of the State of Washington is of major

interest to Federal, state, and local governmental

regulatory agencies, as well as those responsible for

maintaining existing waterways and harbors. Elevated

levels of toxic chemicals exist in bottom sediments of

all the urban bays, with tumors and other biological

abnormalities found in bottom fish associated with

these water bodies. Public awareness of this situation has been heightened by extensive media coverage

of recent government investigations of environmental

conditions in Puget Sound. These investigations and

public concerns have led to three ongoing regional

planning efforts, all of which deal with Puget Sound

water quality and marine bottom sediments. This paper

reports on the Puget Sound Dredged Disposal Analysis

(PSDDA), a 3-year joint Federal-state study primarily

focusing on unconfined, open-water disposal of material dredged from Federal and non-Federal navigation

projects. Study objectives include (a) selection of

unconfined, open-water disposal sites; (b) development

of sampling, testing, and test interpretation procedures to be used in evaluating the suitability of

dredged material for disposal in Puget Sound waters;

and (c) formulation of disposal site management plans.

Preliminary findings for each of these objectives are

discussed for central Puget Sound, which includes the

ports of Seattle, Tacoma, and Everett.

INTRODUCTION

The Puget Sound Dredged Disposal Analysis (PSDDA) is a 3-year study with

primary focus on unconfined, open-water disposal of material dredged from Federal and non-Federal navigation projects. It is a joint study by the Seattle

District, Region 10 of the Environmental Protection Agency (USEPA), and the

Wa .iington Departments of Natural Resources and Ecology. The study began in

Apzil 1985.

Well over one half of the state's population is located in the Puget

Sound area (Figure 1) and about 2.2 million people reside in the metropolitan

133 92-17635
PUGET SOUND, WASHINGTON

Fiur . .uetSun.Wahngo

, GARDNER

HOOD CANAL

• SEATTLE

COCM MACMN

Figure 1. Puget Sound, Washington

corridor of Tacoma, Seattle, and Everett. The Sound is treasured because of

its varied 2,000-mile shoreline and 2,500 sq miles of popular boating waters

used for sailing, power cruising, and fishing. Also, the water body is very

important to the economic well being of the region with foreign and domestic

trade made possible by naturally deep harbors. Throughout the sound nearly

134
2 million cubic yards per year have been dredged over the past 15 years, with

about 40 percent of the dredged material placed in state-designated, openwater disposal sites.

Three main areas of concern have focused public attention on the Sound's

water quality, resulting in public demand for action. First, high levels of

potentially harmful chemicals have been found in marine sediments and organisms, especially in the urban bays near Seattle, Tacoma, and Everett due to

uncontrolled as well as regulated discharges (Malins et al. 1984). Many see

these chemicals as a causal factor of tumors and other biological abnormalities found in bottom-dwelling fish. Second, oceanographers estimate 60 to

80 percent of the water flowing out of the central and south Sound on outgoing

tides is recycled (via tidal "refluxing") back into the system. Most contaminants released into the Sound through point discharge, urban runoff, or an

atmospheric fallout appear to never leave and end up bound to the bottom sediments. Third, there are uncertainties about the long-term health of the Sound

in light of limited knowledge on the cumulative effects of pollutant discharges from human activities.

In the fall of 1984, a Seattle citizen appealing to the Washington State

Shoreline Hearing Board protested a disposal site-use permit, previously

issued to the Department of Natural Resources. This resulted in the closure

of Fourmile Rock, a major long-term, open-water disposal site in Seattle's

Elliott Bay. Other disposal sites have also been closed.

Television, radio, and newspaper coverage of concerns over Puget Sound

water quality have been extensive, leading to a highly sensitized public which

in turn has demanded investigations of perceived problems and corrective actions on the part of regulatory agencies.

Both Federal and state governments have responded to public and agency

demands for action. In early 1984, the Federal Government, through Region 10

of USEPA, developed the Puget Sound Estuary Program (PSEP). This is a longterm effort that has two primary objectives: (a) identification of water

quality problems, and (b) promotion of cleanup actions.

Problem identification activities of PSEP include:

'a. Mapping pollutant loading sources.

b. Evaluating tidal transport of contaminants.

c. Identifying bottom sediment areas of concern defined by either elevated levels of toxic chemicals or depression of benthic biological

communities.

Problem-solving activities of PSEP include the following:

a. Establishing improved chemical and biological testing procedures for

marine sediments.

b. Formulating contaminated sediment cleanup plans for Elliott Bay,

Everett Harbor, Commencement Bay and other areas where contaminated

135
sediments have been identified as being a major concern. Source control (that is, reducing or eliminating the release of harmful chemicals into the Sound) is a key feature of all cleanup plans.

c. Encouraging a Sound-wide, comprehensive examination of dredging and

the disposal of dredged material to deal with what has been perceived

as one possible reason for the spread of contaminants into deeper

waters.

Public feelings about Puget Sound are so strong that protection and

cleanup of its waters became an issue in the 1984 fall elections. After the

elections, the new Governor and the State Legislature established a special

state agency, the Puget Sound Water Quality Authority (PSWQA). This new

agency has considerable powers. Through development of a comprehensive water

quality plan, the agency can require that other state agencies and local governments take corrective actions leading to pollution abatement and improvement of water and bottom sediment quality. The draft comprehensive plan,

distributed for public review in September 1986, covers the full range of

water quality issues including dredging, disposal, and cleanup of contaminated

sediments.

PUGET SOUND DREDGED DISPOSAL ANALYSIS

Goal

The goal of PSDDA is to provide environmentally safe and publicly acceptable guidelines governing unconfined, open-water disposal of dredged material,

improving consistency and predictability in the decisionmaking process.

Objectives

Study objectives are to:

a. Identify acceptable unconfined, open-water disposal sites.

b. Define consistent and reasonable evaluation procedures for dredged

material to be placed at those sites.

c. Formulate site use management plans that will ensure adequate controls and public accountability.

Scope

The PSDDA study is a Sound-wide effort being accomplished in two geographic phases, each about 2 years in length. The phases overlap in time; the

second phase started a year after the first.

Figure 2 shows the geographic coverage of Phase I and Phase II. The

Phase I effort covers the critical central Puget Sound industrial core, where

several major Corps of Engineers' navigation projects are proposed and where

major Federal and state permit decisions are pending, such as the US Navy

homeport at Everett. Phase II of the study covers the north and south Sound.

The phasing has allowed the study to focus on the area having the greatest

need for dredged material disposal sites. Each phase includes an

136
V WA

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INDEX MAP

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NSEND PORT

ANGELES

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Figure 2. Study area--Puget Sound Dredged Disposal Analysis

137
Environmental Impact Statement (EIS) to support subsequent implementing actions. These implementing actions include adoption of evaluation procedures

that define the appropriate tests for dredged sediments and disposal guidelines that will be used to decide what is acceptable for unconfined, openwater disposal.

Participants and Organization

The study is being accomplished using a consensus approach among the four

principal agencies, with close participation by Puget Sound ports, local governments, Indian tribes, environmental groups, and other Federal and state

agencies. Three technical work groups have been established, one for each of

the study objectives (Figure 3). Also shown are the Policy Review Committee,

POLICY REVIEW

COMMITTEE

I

TECHNICAL STEERING

COMMITTEE

F I

DISPOSAL SITE DISPOSAL EVALUATION MANAGEMENT PLAN

WORK GROUP PROCEDURES WORK GROUP

WORK GROUP

Figure 3. Organization--Puget Sound Dredged Disposal Analysis

comprised of the heads of the four principal agencies, and the Technical

Steering Committee, comprised of middle managers from the agencies. The committees meet periodically with the Study Director to review study progress and

discuss policy and technical issues.

CURRENT DREDGED MATERIAL MANAGEMENT

A description of current management practices for dredging and dredged

material disposal in Puget Sound is needed to place PSDDA in perspective.

In comparison to many areas of the United States, annual dredging volumes

in Puget Sound are relatively small. This is attributable to the naturally

steep relief and resulting deep waters. Dredging volumes in the central portion of the Sound (the Phase I study area of PSDDA) for the period 1970-1985

are shown in Table 1.

The table indicates that of the 17.3 million cubic yards dredged between

1970 and 1985, approximately 40 percent was discharged in unconfined,

138
TABLE 1. PUGET SOUND DREDGED MATERIAL INVENTORY, PHASE I AREA

(SEATTLE, TACOMA, EVERETT), 1970-1985

Total volume dredged, cu yd 17,320,000

Total volume disposed to open water, cu yd 6,758,000

Total volume, cu yd, disposed at

Port Gardner 692,000

Elliott Bay 4,598,000

Commencement Bay 782,000

Corps of Engineers Port Other

Projects Projects Projects

Total volume dredged, cu yd 5,755,000 4,635,000 6,930,000

(4,400,000 m3 ) (3,544,000) (5,298,000

Total volume disposed to 2,167,000 1,389,000 3,202,000

open water, cu yd (1,657,000 m3 ) (1,062,000) (2,448,000)

Total volume disposed upland 3,588,000 3,246,000 3,727,000

or nearshore, cu yd (2,743,000 m3 ) (2,482,000) (2,850,000)

Disposal Methods for Corps of Engineers Projects

1970-1979 1980-1985

Volume Volume

cu yd Percent cu yd Percent

Water 818,214 24 1,027,227 54

Upland/nearshore 2,544,766 76 887,274 46

open-water disposal sites in Puget Sound. This represents about 450,000 cu yd

per year to the Sound. The rest was placed in upland and nearshore disposal

sites. Volumes dredged by the Corps of Engineers, the Puget Sound ports, and

others (the private and municipal navigation interests) each constitute about

one third of the total during the period. The ports placed about 70 percent

of their dredged material in upland and nearshore sites, while the Corps and

other dredgers placed only 62 and 54 percent, respectively. These figures

suggest that smaller dredgers (not the ports or Corps) have relied more heavily on unconfined, open-water disposal due to fewer opportunities for land

development (fill) projects.

Another consequence of the steep relief of the Puget Sound shoreline is

that there are few easily accessible upland or nearshore fill areas that do

not conflict with human habitation, industrial activity, and environmental

139
resources (wetlands and fish habitat). As upland and nearshore sites have

become increasingly scarce, the reliance on unconfined, open-water sites has

increased. As can be seen from Table 1, while only 24 percent of the Corps'

dredged material went to open-water sites in the 1970's, over 50 percent has

been going to open water in the 1980's. (This trend has also resulted in several recent uses of the confined aquatic disposal (CAD) (capping) technique.

A major test of this technique is planned by the US Navy for their Homeport

project at Everett, Washington.)

Dredging forecasted to occur over the next 15 years (through the year

2000) is shown in Table 2. A 31-percent increase in potential dredging is

anticipated relative to the last 15 years, primarily due to several large proposed navigation improvement projects. The trend of increasing reliance on

unconfined, open-water disposal is expected to continue, as well as increased

use of confined aquatic disposal. Given the relatively high cost of alternatives to unconfined disposal, the disposal guidelines that determine what material will be considered acceptable for unconfined disposal are recognized as

centrally important to future dredging.

TABLE 2. PUGET SOUND DREDGED DISPOSAL ANALYSIS, PHASE I AREA

DREDGING FORECASTS 1985-2000

Total forecasted dredging volumes, 23,697,000

cu yd

Volumes of material that might consider

use of PSDDA sites, cu yd

Total volume* 19,397,000

Estimated volume that would be 11,218,000

acceptable for PSDDA sites**

Minimum volumes that would require use 5,460,000

of PSDDA sitest

* One large project has been excluded because of a recent determination that

its dredged material will be placed in a confined disposal site. The volume

for this project is shown in the total dredging volume, not in the total

volume that might consider use of the PSDDA sites.

** Sediment chemistry data were used to estimate the volumes of material that

might exceed and pass proposed PSDDA disposal guidelines. These volumes are

being used by PSDDA to examine cost impacts of the alternative disposal

guidelines and to determine needed site capacity for the PSDDA sites.

t This volume represents the material that is estimated to pass the proposed

PSDDA disposal guidelines, without including large (and potentially speculative) proposed port improvement projects, and maintenance projects that

expect to continue to rely on upland and nearshore disposal. These are purposely conservative estimates of the anticipated volumes, which are being

used by PSDDA to analyze user fees (per cubic yard). These fees and possibly state appropriations are expected to pay for proposed site environmental

monitoring.

140
Interim Disposal Criteria

A major factor in the City of Seattle's closure of the Fourmile Rock

Disposal Site was the lack of defined dredged material evaluation procedures.

Historically, testing requirements and test interpretation standards ("disposal guidelines") have been developed on a case-by-case basis for each project. Many past projects were exempted from testing or detailed assessment.

There were no agreed-upon, consistent standards or guidelines for determining

what material was acceptable or unacceptable for unconfined, open-water

disposal.

Water column testing for release of dissolved contaminants during dredging and disposal was primarily relied upon to ensure water quality standards

were being met. However, this testing usually did not reveal any problems, as

little of the contamination was released from the sediment to the water. Multiple tests conducted using sediment elutriation procedures did not indicate

any reason for concern. As we now know, contamination associated with dredged

material is predominantly bound to sediment particles and does not substantively dissolve during the short-term disturbances of dredging operations.

The discovery of elevated levels of chemical contaminants in the disposal site

sediments, and that these sediments were toxic in the solid phase to bioassay

species, underscored the need for redesign of the dredged material evaluation

procedures.

It was in this context that the USEPA and the State of Washington promulgated "interim criteria" for dredged material disposal at unconfined, openwater sites (USEPA 1984). Developed initially for the Fourmile Rock Disposal

Site as a stipulation of the City of Seattle's shoreline permit, a similar

concept is now in place for all state-designated unconfined, open-water disposal sites in Puget Sound. These criteria were proposed as interim, pending

development of better decision guidelines through a Sound-wide approach such

as PSDDA. The evaluation procedures under development by PSDDA are intended

to replace the interim criteria.

The interim criteria require both biological and chemical testing of the

dredged material; and standards for each must be met before unconfined, openwater disposal is approved. Types of tests required vary slightly from area

to area based on the degree of historic contamination potential, but all urban

and industrial areas require similar testing.

With the interim criteria, dredged material sampling requirements vary

from project to project. However, concurrent with promulgation of the

Fourmile Rock interim criteria, the City of Seattle specified the requirement

of having one core for every 4,000 cu yd to be dredged. The 4,000-cu-yd figure was selected as it represented two large barge loads of material, a volume

considered sufficiently large to potentially warrant a separate decision on

acceptability for unconfined disposal.

Chemical testing requirements of the interim criteria cover a fairly limited range of chemicals. Six heavy metals (Pb, Zn, As, Hg, Cu, Cd), 16 polynuclear aromatic hydrocarbons (6 low molecular weight, 10 high molecular

weight), polychlorinated biphenyls (1016, 1232, 1242, 1248, 1254, 1260), and

DDT's (4-4 DDD, 4-4 DDE, 4-4 DDT) are the only decision chemicals, though

141
other base neutral priority pollutants are often requested for analysis. Biological testing of the sediments is conducted via a 10-day, solid phase exposure of amphipods (Rhepoxynius abronius) (Swartz et al. 1984).

Interpretation of test results under the interim criteria is based on

comparison with conditions that exist at the disposal site (for Fourmile Rock)

or in the central portion of the Sound (for the rest of Puget Sound). The decision criteria afe based on the concept of "nondegradation relative to reference," i.e., "in the interim, let's not let it get any worse than it already

is." A major shortcoming of this approach is that the cause-effect relationship between chemistry and biological effects is not considered in setting the

bulk chemical "pass/fail" values. Also, these pass/fail criteria are established for all contaminants present at the disposal site, without regard for

whether they are instrumental in the effects of concern.

Bulk sediment chemical criteria for Fourmile Rock are based on no single

chemical exceeding 125 percent of reference, and no three chemicals exceeding

110 percent. Acute bioassay responses cannot exceed the 25-percent absolute

mortality observed using Fourmile Rock sediments (no corrections relative to

test controls are allowed). The use of these values in disposal decisionmaking has been questioned by both economic development and environmental protection interests--the former noting them as devoid of effects significance,

the latter claiming that an already adverse situation is being perpetuated.

Site Management

The state owns the bottom lands in the Sound. As such, they manage the

existing sites for the Phase I area (see Figure 2). These sites have been in

use since the early 1970's. The state collects a disposal site use fee from

non-Federal users. Federal users, including the Corps, cooperate in the program by using the designated sites and participating in an interagency siting

committee chaired by the state.

Originally, the state planned to monitor the sites. However, disposal

fees were not set sufficiently high enough to provide needed revenue after

administrative expenses were covered. As a result, most of the sites have received no environmental monitoring. A few sites have been examined via special research programs.

DISPOSAL SITE SELECTION

The Disposal Site Work Group (DSWG) agreed early in their deliberations

that disposal sites should be reasonably accessible to the harbor projects.

For the Phase I area this resulted in a strategy of having a site in each of

the major urban harbors of Seattle, Tacoma, and Everett. These multiuser

sites would service all nearby dredging areas.

Strategy

A three-step, tiered screening process was used to select preferred and

alternative disposal sites by application of an approach similar to that outlined in a USEPA/Corps of Engineers (CE) workbook on ocean disposal siting

(USEPA/CE 1984). These steps, shown in Figure 4, were as follows:

142
STEP 1: SELECTION FACTORS OF ZONES OF SITING FEASIBILITY (ZSF)

I. Human Uses (12)

2. Biological Resources (4)

3. Physical Parameters (3)

EVALUATION FACTORS

1. Human and Environmental Health

2. Sediment Containment

3. Biological Resources Health

4. Non-interference with Human Activities

5. Shoreline Buffer Zone

6. Vulnerable Resource Buffer Zone

7. Water Depth Constraints

8. Avoidance of Utility Corridors

RANKING FACTORS

1. Priority 1 ZSF - Minimal Dispersion

- Proximity to Major Dredging

Activity

2. Priority 2 ZSF - Transport Economics

*

STEP 2: ZSF CHECKING STUDIES

i. Site-Specific Field Studies

2. Recommended Preferred/Alternative Sites

STEP 3: FINAL DISPOSAL SITE SELECTION

1. Assimilated Steps 1 and 2

2. Final DSWG Selection and Public input

Figure 4. Siting evaluation and selection strategy

Step 1: Develop site selection factors based on USEPA's "Guidelines for

Specification of Disposal Sites for Dredged or Fill Material," and Washington

State Law, including, among others, the following criteria:

"* Avoid high-energy areas that would disperse dredged material significantly beyond the disposal site area.

"* Avoid significant adverse impacts on foodfish, shellfish, marine mammals, and marine birds.

143
9 Reduce interference with human aquatic and upland uses to the lowest

practicable level.

Step 2: Review existing mapped information and produce map overlays displaying information based on 19 selection factors. Following the map overlay

process, potential disposal siting areas called "Zones of Siting Feasibility"

(ZSF's) were selected that appeared to have minimal conflicts with human uses

and natural resources. This process identified priority ZSF's within Saratoga

Passage, Port Gardner, Elliott Bay, and Commencement Bay. Priority ZSF's were

those sited in low current areas, greater than 2,500 ft from shorelines and

"vulnerable" natural resources, between 120- and 600-ft depths, and located

within 10 n.m. of the nearest center of dredging activity (see Figure 5). Existing data gaps within chosen ZSF's were evaluated by DSWG, and limited field

studies were initiated to further characterize and check the ZSF's. These

field studies are discussed later in this paper.

Step 3: Tentatively select preferred and alternative disposal sites.

Within the ZSF's, this was accomplished using data from steps 1 and 2. Data

from computer simulations of typical disposal operations in deep water provided an assessment of the size of the potential bottom impact area. Computer

studies indicated that, for the sites under consideration, the impact areas

could vary from about 0.4 to 0.5 sq mile, depending upon water depths and

tidal currents. Additional information from site selection studies described

below was used to refine the locations of the preferred site(s) by validating

and verifying the relatively nondispersive qualities of each site, and the

status of biological resources within and adjacent to the site boundaries.

Modeling Studies

A key evaluative factor in choosing a site is the ability to accurately

place material within defined boundaries without significant dispersal beyond

predetermined acceptable limits. Two computer simulation studies addressing

these concerns were undertaken: disposal modeling and current modeling.

Disposal Modeling

Using Puget Sound data, the US Army Engineer Waterways Experiment Station, Vicksburg, Miss., performed a simulation study depicting dredged material disposal in an unconfined, open-water environment. To determine the

behavior of material during actual operations, the model simulated passage of

dredged material through the water column for varying water depths, current

speeds, and sediment type. The conditions applied were representative of

those in Puget Sound--depths ranging from 100 to 800 ft and currents ranging

from 0 to 2 knots. If a circular, 900-ft radius target is assumed, with maximum flood and ebb tide velocities of 0.5 knot, the material would remain

within an area described in Table 3 that is deemed to be the disposal site.

Figure 6 provides a perspective on a ZSF and a disposal site within the ZSF,

which is established from multiple bottom "footprints," or multiple derived

discharges from the computer studies.

144
LEGEND

DISPOSAL SITE , EVERETT

EXISTING

A

DISPOSAL SITE Q

PREFERRED

DISPOSAL SITE

ZONE OF

SITING 4.

FEASIBILITY

SE ATTLE

BR EM ERTON

S• • ;T.ACO MA

Figure 5. ZSF's and alternative disposal sites

145
TABLE 3. DISPOSAL SITE AREA

Amount of Material Current Depth Footprint

cu yd knot ft ft

1,500 0.5 400 3,000 x 3,800

1,500 0.5 600 3,000 x 4,600

Current Modeling

A two-dimensional computer simulation model was used to predict tidal

elevations and horizontal currents in the Phase I area. Spring and neap tide

periods were simulated to obtain average, net, and peak current velocities.

Generally low current speeds were predicted within the Phase I ZSF's.

This modeling was supported by low current velocities measured by current

meter arrays placed at the existing Port Gardner (Everett) and Fourmile Rock

(Seattle) disposal sites.

Field Checking Studies

Field studies were conducted during the fall of 1985 in the Port Gardner

ZSF, Saratoga Passage ZSF, and the two Elliott Bay ZSF's, to provide supplemental baseline biological, current, and sediment transport information.

These data were combined with other available information to aid the DSWG in

selecting preliminary preferred and alternative sites within the ZSF's at each

of the four areas.

Due to weather and scheduling problems, no field studies were performed

at the Commencement Bay ZSF. Existing information was used to select the

Commencement Bay ZSF and the preliminary preferred and alternative disposal

sites.

Other studies conducted during this period included:

a. MANTA survey. A submersible remote operational vehicle (ROV) collected physical bottom data with 90-kHz sidescan sonar and sought

data on biological resources through a low incident light video camera and a 35mm stereo still camera.

b. Remote ecological monitoring of the seafloor (REMOTS) survey. A sediment profiling camera and computer imaging analysis system were used

to provide information on physical and biological (infaunal benthos)

characteristics.

c. Van Veen grab samples. These were collected at selected stations

within ZSF's to ground truth REMOTS observations, provide sediment

samples for grain-size determinations, and archive benthic infaunal

samples for possible future study.

146
Upland

ZONE OF SITING FEASIBILITY N

-Flood N.

DISPOSAL SI1TE

AsTarget Area

B:Oisposal Zone

PLAN VIEW

Water Surfacep Ois tg oo'l

Ebb

'Target Area

1800'

Disposal Zone

ELEVATION VIEW

Figure 6. Disposal site parameters

147
d. Current meter studies. These were conducted at the existing Fourmile

Rock (Elliott Bay) and Port Gardner disposal sites to provide additional information on the current regimes of these two areas. Less

than 2 percent of the time were current speeds measured above approximately 0.5 knot.

e. Fish and benthic resource studies. Sites within the ZSF's were

tentatively selected by March 1986, subject to further verification

and validation from site-specific studies. Site-specific studies of

bottom fish and shrimp and crab resources were conducted over four

seasons, from February through September 1986 within each of the selected sites and surrounding areas. Additionally, questions concerning benthic habitat quality for bottom-feeding fishes in the sites

and adjacent areas were addressed during the summer field studies

using a procedure called the benthic resources assessment technique

(BRAT). This technique provided quantitative information concerning

the benthic habitat quality for bottom-feeding fishes using the site

during summer.

f. Depositional analysis technique. A relatively new approach, known as

depositional analysis, was used to assess whether dredged material

deposited at a site would tend to stay there (Striplin et al. 1986).

For the Phase I area, the work group chose to locate the disposal

sites in relatively nondispersive areas. This was done to (1) reduce

the complexity and cost of field studies, (2) minimize the potential

for adverse impacts to important fishery resources, (3) facilitate

follow-up environmental monitoring of the site, and (4) gain agency

and public acceptance because of program accountability. An assessment of the depositional potential of an undisturbed area can be

determined from a careful analysis of the bottom sediments in that

area. The PSDDA field studies relied on sediment samples from over

200 stations with laboratory analysis used to determine organic loads

and grain size. Previous work by Word et al. (1984) indicated that,

for a given water depth, sediments in Puget Sound tend to accumulate

where three criteria are met: (1) abnormally small grain size, (2)

abnormally high volatile solids, and (3) abnormally high biological

oxygen demand. The abnormally high determinations were made for the

PSDDA data based on whether or not a sediment sample value for total

volatile solids, biochemical oxygen demand, and percent water exceeded the 95-percent confidence interval (CI) for the depth contour

on which the station was located. Figures 7a and 7b show the results

for one of the ZSF's based on a analysis of total volatile solids.

Figure 7a is a mapping of the percent of dry weight values from the

stations, and Figure 7b shows the areas where values exceed

95-percent CI.

Site selection. Preferred disposal sites were selected (see Figure 5) after considering the results of modeling and field studies,

and public and agency views on the alternative sites. A preliminary

findings report was issued to obtain public feedback, and public

workshops and meetings were held to solicit public opinion. In Commencement Bay, the preferred site is very close to the existing site.

148
VASON ~ 4Is. % CRY WEIGHT

is.

*0 05

TACOMA

a. Percent dry weight contours

(tMAU R Y

is.

0 00

b. Areas with Ž!95-percent CI

Figure 7. Depositional analysis - total volatile solids

149
However, in Elliott Bay and Port Gardner, the new sites are nearly

3 miles and 2 miles, respectively, from the old sites. To date, general acceptance has been given to the preferred sites by the public.

EVALUATION PROCEDURES

The dredged material evaluation procedures proposed by PSDDA are primarily focused on deciding when sediment is acceptable for unconfined, open-water

disposal. As such, these procedures address sediment sampling requirements,

chemical and biological testing, test interpretation, and disposal decisionmaking ("disposal guidelines").

Fundamental to dredged material management, the decision of what is acceptable for unconfined, open-water disposal must consider the consequences

associated with disposal of the material that is not acceptable for unconfined, open-water disposal. Therefore, PSDDA is also developing evaluation

procedures and design guidelines for dredging and disposal of contaminated

sediments that are not acceptable for unconfined, open-water or conventional

land/shore, disposal.

Sampling Requirements

The number of samples and analyses required for assessment of a dredging

project is significant both to the cost of testing and to the confidence in

resulting characterization of the impact potential of the material. Yet

sampling intensity has too often in the past received limited attention. To

assist in improving decisions on dredged material sampling, the Evaluation

Procedures Work Group (EPWG) developed sampling and analysis guidelines that

define the maximum volume of material to be represented by each sample and by

each analysis (composite of several samples). These guidelines are shown in

Table 4. The maximum volumes vary by the location of the project (relative to

its potential for contamination due to source discharges) and by the depth of

the cut. While cut depth will depend on the project, PSDDA has provided "location rankings" for most of the dredging projects in the Phase I area. Surface sediments in areas with many contaminant sources are therefore sampled

more intensively than subsurface sediments in areas with few sources. Compositing is done such that the maximum volume per analysis represents a "dredged

material management unit"--a dredgeable, separable volume of material upon

which a decision on acceptability for unconfined, open-water disposal can be

made.

The guidelines do not consider project size. This is due to the high

variability of contaminant distribution within most dredging prisms in Puget

Sound. As an option to the guidelines, the dredger can conduct a pilot study

to determine if the prism variability is such that fewer samples will adequately characterize the material (from a statistical variability perspective). It is anticipated that this option will be useful primarily to new

dredging projects that will be removing large volumes of well-sorted, coarsegrained material.

Testing Requirements

The EPWG has recommended several changes in the types of chemical and biological tests needed for dredged material assessment. First, the work group

150
TABLE 4. SAMPLING AND ANALYSIS REQUIREMENTS

Sampling** Analysist

Maximum 1,000 cu yd/Sample Maximum 1,000 cu yd/Analysis

Surface Subsurface Surface Subsurface

Area Ranking* <4-ft cut >4-ft cut <4-ft cuttt >4-ft cut

Low 8 (6) 8 (6) 48 (37) 72 (55)

Low-moderate 8 (6) 8 (6) 32 (24) 48 (37)

Moderate 4 (3) 4 (3) 16 (12) 24 (18)

High-moderate 4 (3) 4 (3) 4 (3) 12 (9)

High 4 (3) 4 (3) 4 (3) 12 (9)

* Location of project relative to potential for contamination is expressed in

terms of one of five area rankings, e.g., "Low" refers to areas where sediments are known to be relatively uncontaminated, with few discharge sources

of contamination. These location rankings have been predescribed by PSDDA

for the central Sound. Many of the industrial waterways of the central

Sound are ranked "high."

** The minimum number of samples is calculated by dividing the project volume

by the value in the table.

minimum number of analyses SThe is calculated by dividing the surface and

subsurface volumes by the table values. Samples are composited to form

analyses. Compositing plan is determined for each project. Analyses should

represent discrete dredged material management units.

tt In calculating analysis requirements, project volume located above a cut

depth of 4 ft is considered separately from volume below this depth. The

4-ft cut represents a dredgeable lift (±2 ft vertical precision).

reviewed available data on chemicals discharged to Puget Sound, which of these

were present in Sound sediments, and what toxicological implications each had,

and recommended adding several chemicals to the chemical analysis list. Chemicals to be added include other metals (Cr, Ni, Ag, Sb) and chlorinated hydrocarbons (e.g., chlorinated butadienes). The work group also standardized the

list of conventional sediment parameters to be measured.

For biological testing, the work group has recommended the use of multiple species in the acute toxicity testing to better represent the diversity of

aquatic species of concern during disposal. Tests to be included are the

10-day amphipod mortality test, the 4-day oyster larvae abnormality, and the

15-min EC50 luminescent bacteria photoinhibition test (microtox) (Schiewe

et al. 1985). Additionally, for more contaminated materials, the 30-day bivalve bioaccumulation test is needed.

While none of the above recommendations are necessarily new, EPWG has

proposed to link the previously separate chemical and biological testing

steps. Rather than always conduct both chemical and biological testing, the

151
work group has recommended that the need for biological testing be based on

the results of chemical testing. At low levels of chemical contamination

(below screening level chemical concentrations), no biological testing is

required in order to recommend unconfined, open-water disposal. At very high

levels of chemical contamination (above a maximum level chemical concentration), biological testing is not necessary to indicate that unconfined, openwater disposal would be inappropriate. Interpretation of chemical and biological tests (the disposal guidelines) has been developed using this linked,

effects-based approach.

Disposal Guidelines

The basis of the disposal guidelines developed under PSDDA is the

avoidance of adverse biological effects due to sediment contamination. This

contrasts with the existing approach of relying on comparison to reference

conditions (per the interim criteria).

Early in the planning process, PSDDA recognized that the decision on what

degree of dredged material contamination is acceptable for unconfined, openwater disposal was not a simple, black and white decision. Many of the study

participants held very different views on the degree of acceptable adverse effect at or around the disposal site. Uncertainties in scientific information

further emphasized this gray area in decisionmaking. To address this issue,

PSDDA defined four alternatives describing the boundary between acceptable and

significant adverse environmental effects on biological resources due to

sediment chemical contamination. The alternatives described four degrees of

increasing effect on resources at the disposal site, from "no effects due to

sediment contamination" to "major effects due to sediment contamination."

Each of these alternatives were further defined by representative laboratory

test results that were considered indicative of the potential effects in the

field.

Though preliminary, PSDDA has recommended the alternative labeled "minor

adverse effects on biological resources due to sediment contamination." This

alternative allows adverse effects within the site boundaries that are predominantly sublethal and developing only after chronic exposure. In laboratory

terms, dredged material meeting this definition does not exhibit significant

acute mortality in sensitive test species exposed to the sediment to be

dredged.

PSDDA chemical test interpretation is based on effects information obtained from field samples where chemistry is compared with biological response. The concept utilized is the apparent effects threshold (AET) (Tetra

Tech, Inc. 1986). Illustrated in Figure 8, the AET relies on field and laboratory effects data to calculate chemical-specific sediment quality values.

By definition, the AET is the highest concentration observed in a biological

response database that did not evidence significant adverse response. The resulting values do not necessarily indicate causal response for each chemical,

but rather are indicators of combined chemical effects present in the database. In support of this approach, there are no significant adverse biological responses (occurring below an AET) that are not above an AET for another

chemical. Therefore, applied as a set, the AET system has a high efficiency

in correct identification of sediments with adverse biological response.

152
- AET UNCERTAINTY

"q-1-NO SEDIMENT TOXICITY-.m

SEDIMENT TOXICITY OBSERVED

I I

g

I I

I I i

I I I * I

11 ppm 30e ppm 6300 ppm

CONCENTRATION I I ........... ... APP I N ... . . ....... - (mg/kg DW) 1¶0 1 00 1000 10000

APPARENTI

EFFECTS

THRESHOLD

Figure 8. Apparent effects threshold determination

AET's can be (and have been) developed for any number of biological response indicators, lab and field. The maximum level proposed by PSDDA is the

highest AET among four (mortality of amphipod species, abnormality of oyster

larvae, microtox, and field benthic community degradation). This is the concentration where all biological indicators (lab and field) have become consistently, significantly adverse. The screening level was set at 10 percent

of the maximum level, as long as this value was at or above reference area

values (for relatively clean and undisturbed areas) and below the lowest AET

(where one biological indicator has become consistently adverse).

Figure 9 shows the relation of the PSDDA values to reference area values

and interim criteria for several chemicals of concern in Puget Sound. An

important feature of this system is that the dredging project's "pass" (acceptable for unconfined disposal) and "fail" (unacceptable for unconfined disposal) values have been separated. In contrast, the interim criteria have

combined pass/fail volumes. In most cases, the screening level is below

Fourmile Rock values, while the maximum level is above the Fourmile Rock

values.

Biological testing is not needed when all chemicals are below screening

levels, or when any two chemicals are above maximum levels (or one greatly

above). Biological testing is conducted for all other cases. Interpretation

of acute tests is shown in Table 5. Single species response guidelines are

changed from 25 percent in the interim criteria to 50 percent in the proposed

PSDDA approach. In addition, if any two of the PSDDA test species show significant toxicity (even if not 50 percent), then unconfined, open-water disposal is not recommended.

Past interpretation of bioaccumulation tests has relied on statistically

significant chemical increases in tissues of test species relative to reference species (often from a relatively clean area). With the sophisticated

analytical equipment available today, the finding of statistically significant

increases of organic chemicals in test species tissues is increasingly common.

153
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CONTAMINATION PUGET SOUND

PCB 36- CRITERION

SCREEN -- 250

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REFERENCE

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CONTAMINATION

HPAH 2690 PUGET SOUND

SCREE" CRITERION SCREEN 10

LEVEL 6

REFERENCE

(ppbdry) 229 RBAY

(• BIOLOGICAL TESTING REQUIRED)

Figure 9. Comparative chemistry

154
TABLE 5. INTERPRETATION OF BIOASSAY TESTS

Response Relative To

Control* Reference**

Amphipod (10-day mortality) < +50%t and + SSt5

Oyster larvae (4-day abnormality) < +50%t and + SS

Bacterial bioluminescence NA* > -50%t and - SS

("microtox") (15-min EC50)

* Control sediment is collected from the source of the test species, typically sand. Control toxicity should not exceed 10 percent.

** Reference sediment is collected from relatively undisturbed areas, a match

to dredged material grain size. Reference toxicity should not exceed

20 percent.

t +50% means less than 50 percent higher test response relative to control

response. -50% means less than 50 percent lower test response relative to

reference response. Values shown are those where a single test result (one

of three) will indicate that dredged material is not acceptable for unconfined, open-water disposal. If any two of the three tests are significantly

different from both control and reference, unconfined, open-water disposal

will not be recommended, even without a 50-percent result.

ft SS = statistically significant.

SControls for microtox testing do not use sediment and are not included in

decisionmaking.

This is especially true when the reference area does not contain the chemical

of interest. The finding then raises the issue of effects--what does the

presence of chemicals in the tissues of test species mean?

In addressing this issue, PSDDA has opted to relate bioaccumulation test

results primarily to human health concerns; i.e., when those chemicals of

human health concern are elevated in the sediments, the 30-day bioaccumulation

test is used to determine bioavailability of these chemicals. The chemicals

used are those for which cancer potency (CP) values and reference risk dose

(RFD) values (previously known as acceptable daily intake values) exist.

Applying exposure analysis and CP and RFD models to the disposal sites, PSDDA

has developed target tissue concentrations for interpreting bioaccumulation

test results relative to human health concerns. Dredged material that produces lab tissues that exceed these values would not be recommended for unconfined disposal.

For material that is not acceptable for unconfined, open-water disposal,

PSDDA is developing testing and design guidelines to assist in decisions on

the disposal of these materials. Working through the Waterways Experiment

Station, PSDDA has developed a framework for selecting needed design controls

and treatment for contaminated sediments requiring confined disposal. The

framework, known as the Dredged Material Alternative Selection Strategy

(DMASS) (Cullinane et al. 1986) is undergoing refinement by EPWG to define

acceptability guidelines for specifying the needed design features.

155
DISPOSAL SITE MANAGEMENT

The Management Plan Work Group is developing a management plan for each

of the open-water disposal sites. The plan will define the roles of local,

state, and Federal agencies. Issues include: permit application reviews and

processing, permit compliance inspections, treatment of permit violations,

disposal site environmental impact monitoring, responding to unforeseen site

disposal effects, plan updating, and data management.

The following are preliminary findings and tentative conclusions for some

of the issues addressed by this work group:

a. Permit compliance. Periodic permit compliance inspections will help

ensure that assigned disposal sites are properly used. The cost of

these inspections will be borne by the project sponsors. Options

considered range in cost and certainty from voluntary compliance to

independent verification of all facets of site use. Self-monitoring

by disposers with spot-checks by regulatory agencies is felt to be

the most feasible option. A navigational positioning study concluded

that a 600-ft radius target area should be used to ensure that all

disposals occur within a 900-ft radius disposal zone (see Figure 6).

The smaller target would compensate for some positioning uncertainty

at the perimeter of the target area.

b. Navigation positioning at the disposal site. A navigational positioning study suggests that a combination of LORAN and variable range

radar would be a relatively inexpensive and accurate positioning

method in areas that fall outside the scope of the Coast Guard's Vessel Traffic Service (VTS). VTS is currently being used to verify positioning before disposal at the Fourmile Rock disposal site. A buoy

is proposed for Port Gardner, where LORAN signal inference problems

have been experienced.

c. Local government coordination. A survey conducted of local shoreline

control programs revealed significant differences among cities and

counties as to the handling of dredging and dredged material disposal. PSDDA is attempting, through coordination, to achieve uniformity and consistency in local government controls.

d. Regional disposal sites. PSDDA is considering regional open-water

disposal sites that will serve the needs of all cities and counties

located within each region. One shoreline jurisdiction will be

responsible for meeting the needs of all jurisdictions within their

region. By participating in site selection and establishment of

dredged material evaluation procedures, local governments will be assured that disposal will be environmentally safe, wherever it occurs,

while meeting the economic development needs of their communities.

e. Environmental monitoring. Each of the three Phase I area disposal

sites will be monitored for physical, chemical, and biological

effects resulting from site use in accordance with the PSDDA guidelines. The environmental monitoring is intended to ensure dredged

material disposal accountability by field verification of predicted

site conditions following disposal site use. Monitoring, as now

156
proposed, would involve before and after disposal surveys including

sediment characterization onsite and offsite. Benthic infaunal tissue analysis would be performed at offsite stations to determine if

any unexpected adverse biological impacts have occurred. The monitoring would be paid for by the State of Washington and by dredgers

themselves through disposal site user fees.

PSDDA STATUS AND RELATION TO OTHER PUGET SOUND ACTIVITIES

As mentioned earlier, the cleanup of urban bays is a major activity of

the Puget Sound Estuary Program (PSEP), which is also evaluating application

of sediment quality values based on the AET concept. In their application,

exceedance of sediment quality values would initially be used to identify

areas where contaminant sources need to be controlled. They are additionally

being considered for use in identifying sediment that is sufficiently hazardous in place to warrant removal or in situ confinement (remedial action). As

part of their study, PSEP is responsible for evaluating unconfined, open-water

disposal sites previously used for dredged material. PSDDA has coordinated

closely with this other program, especially in the areas of sediment quality

value and standard methods protocol development.

Another program in Puget Sound that is addressing sediment contamination

issues is the comprehensive plan of the Puget Sound Water Quality Authority

(PSWQA). The broad charter of PSWQA requires this state agency to act in a

review mode for the products of PSDDA. The PSWQA draft comprehensive plan

calls for the development of sediment quality standards for the Sound and for

identification of multiuser, confined disposal sites for contaminated sediments that are unacceptable for unconfined disposal. While close coordination

continues to be needed in areas where the two programs (PSDDA and PSWQA) overlap, the initiative for confined disposal sites is a welcome, and needed, complement to the PSDDA effort.

The release of the PSDDA Phase I draft Summary Report and EIS is scheduled for spring 1987. Several technical reports on the siting studies and

development of sediment quality values will be published prior to that time.

After completion of necessary reviews and securing shoreline permits from

local government, the new PSDDA-developed sites and procedures should be in

operation in Puget Sound by November 1987. Efforts for the rest of the Sound

(Phase II) will be completed in 1988.

Prior to implementation of any of the work group recommendations, PSDDA

is conducting an analysis of the cost implications of the proposals. Final

recommendations will need to consider both economic and environmental consequences, and must also await public review and input scheduled for next year.

Early response to the proposed changes has been favorable, as the new disposal

sites, management plans, and evaluation procedures provide an objective, comprehensive, and long-term plan for dredged material management in the Sound.

REFERENCES

Cullinane, M. J., et al. 1986. "Guidelines for Selecting Control and Treatment Options for Contaminated Dredged Material," US Army Engineer Waterways

Experiment Station, Vicksburg, Miss.

157
Malins, et al. 1984. "Chemical Pollutants in Sediments and Diseases of

Bottom-Dwelling Fish in Puget Sound, Washington," Environmental Science and

Technology, Vol 18, No. 9, pp 705-713.

Schiewe, M. H., et al. 1985. "Use of a Bacterial Luminescence Assay to

Assess Toxicity of Contaminated Marine Sediments," Can. J. Fish. Aquat. Sci.,

Vol 42, pp 1244-1248.

Striplin, P. L., et al. 1986. "Puget Sound Sediment Deposition Analysis."

Swartz, R. C., et al. 1984. "Phoxocephalid Amphipod Bioassay for Marine Sediment Toxicity," ASTM STP.

Tetra Tech, Inc. 1986. "Development of Sediment Quality Values for Puget

Sound."

US Environmental Protection Agency. 1984. "Interim Decision Criteria for

Disposal of Dredged Material at the Four-Mile Rock Open-Water Disposal Site."

US Environmental Protection Agency/US Army Corps of Engineers. 1984. "General Approach to Designation Studies for Ocean Dredged Material Disposal

Sites," draft workbook.

Word, J. Q., et al. 1984. "Subtidal Benthic Ecology, Renton Sewage Treatment

Plan Project: Duwamish Head Baseline Study."

158
AD-PO06 903

REMOVAL WORK OF ORGANIC DEPOSIT BY OOZER PUMP DREDGE

K. Fujii, F. Otsu

Japan Dredging and Reclamation Engineering Association

BACKGROUND

Through drains from homes and factories, rivers that run adjacent to

large cities are becoming more contaminated, worsening the living environment

of residents along with development of the cities. The increase in contamination load is caused by the solution and elution of eutrophic salts from the

contaminated bottom deposits.

The quality of water in rivers and lakes, which had been progressively

deteriorating along with economic development, is today being gradually improved through elimination of contamination by strengthening the regulations

for drainage standards and development of sewage works, etc. However, of the

rivers that are designated "First Class," environmental standards are met in

only about 75 percent of the cases; the remaining cases are unsatisfactory.

Dredging is the purification method of the bottom deposit most often

selected. This paper outlines the work of dredging, dehydration, and treatment of surplus water of the subsoil by means of the transportable modular

Oozer pump dredge.

PURIFICATION OF RIVERS ADJACENT TO CITIES

Controlling Pollution Sources

Controlling the pollution sources is the most basic and essential method.

It includes the perfection of sewage works and the regulation of drainage,

both of which should be planned and executed by the municipalities concerned.

Treatment of Bottom Sludge

Bottom sludge increases the pollutant load of the water by the elution of

eutrophic elements, which greatly affects water quality. Furthermore, surface

turbulence and suspension during flooding is also of great concern. To treat

the bottom sludge, capping, on-the-spot solidification, or dredging is usually

conducted. Table I shows typical bottom sludge treatment methods of rivers

adjacent to cities.

Introduction of Purification Water

Though it has some effect by diluting the water quality or preventing the

stagnation of flow, the overall pollution load is not changed, and there is a

possibility of spreading contamination to a wider area. It is only recommended as a supplementary method to other measures. Also, this method is

sometimes accompanied by economic problems such as construction of the estuary

weir and complicated problems concerning water utilization and river

improvement.

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DREDGING EXAMPLE

Of all the purification methods for rivers, dredging is the one most

often used for disposal and treatment of bottom sludge. The following paragraphs introduce a project for the removal of organic sludge at Oxbow Lake

(which was short cut by a new water-controlling work and became an old river

at the winding river mouth).

Disposal and Treatment of Flow

Disposal and flow treatment flowcharts Are shown in Figure 1.

Dredging

Dredge Requirements

Since this work has as its objective the removal of the deposited bottom

sludge in the old river as part of the Pollution Control Project, the dredging

should not cause environmental pollution. The dredging should satisfy the

following conditions:

a. Dredging is possible without fear of stirring, diffusion, etc., cf

sludge.

b. Dredging is possible with high concentration so as not to agitate the

sludge.

c. Facilities are available to collect and dispose of the gas generated

from the sludge by the dredging.

d. Dredging is effective and economical.

e. The equipment can be transported overland.

Dredge Characteristics

Table 2 shows the adaptability of different dredges which meet the requirements of selection listed above.

Selection of Dredge

In consideration of the requirements and the characteristics of available

dredges, #1 Oozer pump (transportable, modular), which can be transported

overland, was selected. The specifications, operation, arrangement, assembly,

and suction inlet are detailed in Table 3 and Figures 2-5.

Transportation/Assembly

The #1 Oozer dredge was constructed in a compact form to remove sludge on

small- and medium-sized rivers, canals, and lakes. The hull consists of eight

divisional floats, and the driving parts are made of units for each operation.

Therefore, it can be transported overland and assembled and disassembled in

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TABLE 3. SPECIFICATION OF A SLUDGE DREDGE

Ship's name #1 Oozer pump

Vessel type Eight divisional hull type

Vessel shape 25.0 m (L) by 10/0 m (W) by 1.5 m (D) by

1.0 m (draft)

Displacement 142 tons

Main generator 175 KVA (210 PS), 1 unit

Subsidiary generator 5 KVA (6 PS)

Pump type Oozer pump energy-saving type

Pump output

Suction -500 mm HG by 10.0 m3 /min vacuum pump, 1 unit

Outlet 17 m3 /min by 170 PS compressor, 3 units

Dredging depth -12.0 m

Quantity of solid 30-60 m3 /hr (mixture: 100-300 m3 /hr)

dredged permit

time

Suction mouth shape Drag type B:1.4 m by H:0.4 m

Delivery tube 0250 umm

diameter

places where waterway transport is impossible. Also, the ladder shears and

spuds can be tilted to pass under bridges and overhead crossing as low as 3 m

above the wc'ar.

Vehicles needed for overland transportation include:

a. 11-ton truck 2 units

b. Pole trailer 1

c. Low-deck trailer (9.0- by 3.2-m deck) 2

d. High-deck trailer (12.0- by 2.8-m deck) 7

e. Truck crane (100-ton haul) I (for assembly/

disassembly)

f. Truck crane (35-ton haul) 1 (for assembly/

disassembly)

Hull divisions are shown in Figure 6. The assembly process is shown in

Figure 7.

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Type Measurement Number

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C 10. 40m x 3. 50m X 1. 50m 2

Figure 6. Hull division drawing

Discharge of Sludge

Sludge Discharge Basin

In order to speed dehydration from the bottom in addition to surface sun

drying, perforated vinyl pipes with clog preventives (Table 4) were buried

under the sandmat to discharge outside the bank (Figure 8).

Sludge Discharge Pipe

The sludge discharge pipe is detailed in Figures 9-12.

Residual Water Treatment

The water quality standard for the discharge water is:

SS density 25 ppm (25 mg/1)

pH 6.5-8.5

The residual water treatment process is illustrated in Figures 13-17.

OPERATION RESULTS

Soil Property

The properties of the bottom soil are shown in Table 5.

Dredging

Dredging Capacity

The overall average for 8 years was as follows:

a. Operation rate: 76.6% (per day of operation).

b. Operation hours per day: 18 hr 11 min.

169
a. Transportation of b. Assembly of the

components to the hull parts

assembly site

c. Fixing of driving d. Fixing of ladders

compartments and Oozer pump

e. Assembly completed

Figure 7. Assembly process

170
TABLE 4. CLOG PREVENTIVE DEVICE (TOUGHNER MAT u-60 PROPERTY VALUE)

Item Property Value

Weight, g/m 3 300 ± 30

Thickness, mm sby. 3

Tensile strength, kg/5 cm Lengthwise over 50, breadthwise over 20

Ductility, % Lengthwise over 80, breadthwise over 90

Tear strength, kg Lengthwise over 15, breadthwise over 25

Coefficient of permeabil- Horizontal: over 1 x 101-; perpendicuity, cm/sec lar: over I x 102

0 Standard cross section of

sludge discharge basin

Sandmdmt1 t 30 c

Vinyl seat// • /d

installederf 1 0.2% Perorte Toughner Mat

Ftone-Filled

Drain3

S• Sandmat- C

__ ~Perforated.•

\-Toughner MatFigure 8. Stone-filled drain plan

171
unit " mn

S709

500 3A50 5001

L4.500I

•J -'1ioK Flange

S~5.500

-'5500Rubber joint

t = 0.8 5

Figure 9. Structure of floating pipeline

T-pipe

Rubber joint

On-water On-land

section section

Rubber joint Rubber joint Small bank

•',oatinspipeline / • .:ý . • /e

flai..pSludge discharge pipe

Figure 10. Starting point of land pipe

172
Switch Square Empty valve timber drum

Figure 11. Sludge discharge basin receiving piping plan

Basin A Filtering

Outlet pool

Outlet

1st

settling basin

Shore line

On-land 6563 ute On-scaffolding 426m

Total 1.0823

Starting point of land pipe

Figure 12. Sludge discharge basin on-land arrangement plan

173
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PUMP

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PAC

reservoir

Injection pump

Figure 14. Treatment processing

Sludge discharge Sedimentation

basin basin

R~esidual water Lie mixer solids °f

(Discharge basin) i Addition of (Condensation

i coagulant sedimentation)

(Rapid

agitation) I

Inorganic Jg-oeua coagulant igh-molecular

aid (PAC) Icoagulant

Figure 15. Coagulant addition

175
High-molecular Inorganic

coagulant (EDP) coagulant aid

(PAC)

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8ate watethor

(Exhaust of Curren Wtr

residualn reiulo oaer

water) I t/rsdulwtr

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Figure 16. Line mixer

PAC reservoir Residual water treatment

ReIda water treatment orl um

eac-hilue plant :tdedshag ai

Figur 17.Sludge discharge basin

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177
c. Quantity of solids dredged per unit time (production): 51.5 m3 /hr.

d. Apparent suspended solids concentration: 22.9%.

Yearly details are provided in Table 6.

Dredging Precision

Figure 18 shows examples of the dredging precision. The actual result

was 0 cm on the minus side and a maximum of 80 cm on the plus side against the

required depth of dredging. The average extra dredging was 20 cm.

Pollution

As shown in Table 7, SS values sometimes showed an increase of about

10 mg/I and in other times a decrease; overall, however, pollution proved to

be minor when compared with the ordinary pump dredge or the grab dredge.

Residual Water Quality

Table 8 lists the residual water quality values at each treatment processing. The pH value of the permeated water of 6.0 (which is more acidic

than standard) is thought to be the result of the iron ions contained in the

bottom sludge. However, since there is only a small amount of water involved,

it seems to have no influence on the overall project.

Change in Soil Quality

After Sludge Discharge

Figure 19 shows the chronological changes in the water content of the

bottom sludge discharged into the sludge discharge basin.

SUMMARY

The removal of sludge in designated old rivers is part of the Environment

Pollution Control Project of rivers adjacent to cities. This removal was

carried out by dredging using the Oozer pump dredge, with dehydration through

bottom drainage in the sludge discharge basin along with sun drying. The residual water was then treated.

Dredging Capacity

The capacity of dredging by #1 Oozer dredge turned out to be about

50 m/hr (its nominal capacity is 60 m/hr). Even though the hard bottom layers

with low water content near the riverbed, and rocks, boulders, and other obstacles affected the capacity, an improvement in the capacity must be made

(Table 6).

Dredging Precision

The average dredging depth was 20 cm over the target depths, which is a

satisfactory result (Figure 18).

178
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181
TABLE 8. RESIDUAL WATER QUALITY AFTER TREATMENT

(FOR THE LAST 3 YEARS)

Measurement Execution Year

Point Item 6th 7th 8th

Discharge basin pH 7.2 7.4 7.0

SS mg/1 1,135 2,930 1,696

Ist sedimentation pH 6.7 7.2 6.6

basin SS mg/i 49 18 38

2nd sedimentation pH 6.9 7.0 6.7

basin SS mg/1 24 13 16

Effluent water pH 6.9 6.8 6.8

SS mg/i 20 10 15

Wrung water pH 6.0 6.7 6.9

SS mg/i 4 8 16

Standards for Allowable values: pH 6.5-8.5

release water SS below 25 mg/i

Measurement point

(a) Overflow in discharge basin

(b) Overflow in sedimentation basin

(c) Effluent water

(d) Wrung water

(1)

(d)

182
00 Legend: o Upper stratum

A Middle stratum

400. a Lower stratum

400

0

4J

$4-

0)

r.) 200-

0

4 0 05days 60days

01

10 50 100 500' 10,00 5.0,00 1 0.000

Time, hr

Figure 19. Chronological changes of water content per hour

Pollution

Pollution from the dredging did not show any noticeable differences in

places and does not greatly influence the work (Table 7).

Residual Water Quality

The residual water quality conforms to the allowable standards for release water (pH of 6.5-8.5; SS below 25 mg/1 (Table 8).

Change in Soil Quality

After Sludge Discharge

In this project, sludge was dredged, discharged into a basin, dehydrated

via sunshine and the stone-filled drain pipe, and dumped at a site on the

river about 10 km away. The water content after discharge dropped to about

half in 1 year (Figure 19) and caused no problems in transfer or disposal by

the dumptruck.

The removal of the organic deposit in the river by the Oozer pump dredge

ended with satisfactory results in precision, pollution, quality of the residual water, and dehydration in the discharge basin, although dredging capacity

had room for future improvement. Therefore, this process is effective as a

purification measure of rivers adjacent to cities.

CONCLUSIONS

There is an increased contamination load in rivers adjacent to large

cities due to drains from homes and factories, and water pollution caused by

eutrophication due to solution and elution from sludge of bottom deposits is a

social problem. To solve this problem, various disposition and treatment

183
methods, including removal of sludge, have been used. This paper outlined one

method--dredging, disposal, and treatment. Dredging was conducted using the

transportable modular Oozer pump dredge, and the removal work is still

ongoing.

Rivers adjacent to cities are expected to provide sites where citizens

can relax and enjoy the site's natural beauty and harmony. We request that

the authorities concerned with rivers adjacent to large cities ensure that the

rivers be cleaned by the rapid development of sewerage works in tributaries,

the removal of bottom deposits, and the self-purification of the river.

184
SEDIMENT CONTROL ON LAKE EUTROPHICATION

USING AN ECOLOGICAL MODEL

M. Hosomi, R. Sudo

Laboratory of Freshwater Environment

National Institute for Environmental Studies

Yatabe - machi, Tsukuba, Ibaraki 305, Japan

and

M. Okada

Department of Chemical Engineering rn

Tokyo University of Agriculture and Technology Naka - machi, 2-24-16, Koganei, Tokyo 184, Japan

INTRODUCTION

Eutrophication of closed water bodies is still one of the major environmental concerns in Japan. The percentage of lakes and reservoirs whose water

cannot satisfy the Environmental Quality Criteria is the lowest when compared

with those of rivers or sea areas (Environment Agency of Japan 1985). For the

conservation and restoration of closed fresh waters, the Environment Agency

enacted a new law, "Law Concerning Special Measures for Conservation of Lake

Water Quality" on 13 May 1983. Local governments are required to make all

possible efforts for eutrophication control, such as removal of polluted bottom sediments, artificial aeration/circulation, and reduction of nutrient

loads.

Ecological models are widely used for assessing the effectiveness of various means for eutrophication control (Nyholm 1978, Orlob 1983, Matsuoka

1984). However, most conventional models presuppose that release rates of

nutrients from bottom sediments are constant or are given by a forcing function (Larsen, Mercier, and Malueg 1973; Imboden and Gachter 1978; Gulliver and

Stefan 1982). Sediment submodels, therefore, are rarely incorporated into the

ecological models (Jorgensen 1976). Strictly speaking, it is almost impossible for these models to predict the effects of sediment dredging and/or reduction of external loadings on the profiles of nutrient concentrations along the

depth of sediments and, consequently, interaction (i.e. release and sedimentation) between bottom sediment and overlying water.

The purpose of this study is to develop an ecological model of a lake,

Lake Yunoko, combined with a dynamic model of bottom sediments and to assess

various policies for eutrophication control with special emphasis on management of the bottom sediment.

STUDY AREA

Lake Yunoko is well known for its trout fishing and its hot spring resort

in Nikko National Park. However, wastewater from lakeside hotels has been

92-17637
accelerating lake eutrophication. Lake Yunoko (Figure 1) is a dimictic lake

(mean depth - 7.4 m, surface area - 0.35 km2 ) with a hydraulic retention time

of ca. 40 days.

S Lake

0i Yunako

Tokyo Odobu River

Siran.zaw. River

YurnotO Wastewater 4

tregtifleit plant

G r o u n d w a t e J J . ' - ' " r q " , e

asepage S. t r3 Figure 1. Lake Yunoko

/ akeC r

St.2 AI

Yut skl F ells

Inflows include the effluent from Yunoko Wastewater Treatment Plant,

Odobu River, and groundwater seepage. The only outflow is Yutaki Falls.

Intensive limnological surveys were carried out to obtain basic information both for construction and verification of the ecological model and to

assess the response of the lake to advanced wastewater treatment for phosphorus removal, a phosphorus detergent ban, and dredging of the lake bottom

sediment (Tochigi Prefectural Government 1978; Hosomi et al. 1984; Hosomi,

Okada, and Sudo 1986).

These investigations revealed Lake Yunoko to be eutrophic. Chlorophyll-a

concentrations often exceed 20 vg/1. Total nitrogen and total phosphorus concentrations in the epilimnion ranged from 0.2 to 0.8 mg N/I, and from 0.02 to

0.10 mg P/t, respectively. Bottom sediments were found to accumulate large

amounts of organic materials (18-21% I.L., 1.6-2.7 mg P/g, 6-7 mg N/g) and

sulfide. At present, the local government is planning to dredge all the contaminated bottom sediments.

MODEL STRUCTURE

The model proposed in this study is an ecological model combined with the

water temperature model. This is a logical extension of the one-dimensional

stratified deep reservoir model of the Water Resources Engineers, Inc. (WRE

1969) or the Massachusetts Institute of Technology (MIT) (Huber, Harleman, and

Ryan 1972) type in order to include vertical transport of dissolved and

186
particulate materials. The model, therefore, should be called a onedimensional, water temperature-water quality ecological model and is basically

similar to LAKECO developed by Chen and Orlob (1975), which is embodied in the

package WQRRS (Water Quality River-Reservoir Simulation) of the Hydrologic

Engineering Center of the US Army Corps of Engineers (HEC 1978).

This model incorporated a detailed sediment submodel to simulate the

nutrient cycle between water and sediment and to predict concentrations of

dissolved and particulate nutrient in bottom sediments.

As Lake Yunoko is ice covered in winter (Mori and Yamamoto 1975), a onedimensional water temperature model such as WRE and MIT cannot simulate the

phenomenon of ice covering and melting. The Energy Balance model (Greene

1981) was introduced into the MIT model to simulate ice covering and melting

and profiles of water and ice temperature during ice-covered periods.

Figure 2 shows the relationships among the various constituents of the

aquatic ecosystem. Available nutrients consist of AV-P (dissolved inorganic

phosphorus) and AV-N (dissolved inorganic nitrogen). Unavailable nutrients

correspond to detritus phosphorus and nitrogen because dissolved organic phosphorus and nitrogen concentration is low in Lake Yunoko (Hosomi et al. 1984).

ATMOSPHERE

AO B

AAvailable N /P

0oo PhytoplankWon 1M 2 UnaiblN/

Ri Diatom /Others G nvial /

Figure 2. Schematic diagram of RG2 E

the structure of the

ecological model

proposed in this /

studyII I ///////

A aeration, B :bacterial decomposition, E : excretion,

Gi growth, G2: grazing, MI: mineralization,

M2: mortality, P : photosynthesis , R : respiration,

R2 : release, S :sinking, SOD sediment oxygen demand

Dominant species of phytoplankton in Lake Yunoko are diatom such as

Asterionella formosa, Synedra acus, and Fragilaria crotonensis and flagellatae

such as Uroglena americana and Cryptomonas sp. (Hqsomi et al. 1984). It was

found that sinking velocity of diatom such as A. formosa is much higher than

that of flagellatae (Smayda 1964, Titman and Kilham 1976, Hosomi et al. 1984).

Also, large diatoms are considered not to be grazed easily by Keratelza

cochlearis and Bosmina Zongirostris, which are dominant species of zooplankton

in Lake Yunoko. Accordingly, in this model, phytoplankton were divided into

two types: diatoms and other phytoplankton such as Cryptophyceae and

Chrysophyceae.

187
Figure 3 is a schematic diagram of the structure of the sediment submodel. The basic concept of this submodel is equivalent to the nitrogen

release model developed by Hosomi, Okada, and Sudo (1985) and includes the

transformation process of phosphorus and/or nitrogen compounds and the

sedimentation process.

WATER

SADiatom/Others

IDi illS !lSlll II I S 

Id Iayer SA-P SED-P

2d layer SA'-Pte SED-PI S -N-Di SE -N

SA sediment accumulation and compaction

AV- P available phosphorus, AV-N available nitrogen,

UV- P unavailable phosphorus, UV -N unavailable nitrogen ,

SAy-P dissolved phosphorus in pore water,

SAy-N dissolved nitrogen in pore water,

SED-P: particulate phosphorus in sediment,

SED-N :particulate nitrogen in sediment,

Di : diffusion , S :sedimentation , De :decomposition , A :adsorption

Figure 3. A schematic diagram of the structure nf the

sediment submodel proposed in this s

188
Sediment accumulation by continuous deposition of particulate matter

(allochthonous and autochthonous) at the surface layer of the bottom sediment

shifts the sediment/water interface upward in reference to a fixed datum. In

this model, this velocity term was defined as sedimentation rate.

Sedimentation processes include sedimentation of particulate phosphorus

and nitrogen in the sediment and diffusion of available phosphorus and nitrogen in the pore water along with concentration gradients. Transformation processes of phosphorus and/or nitrogen compounds in the sediment-water system

are as follows:

a. Deposition of unavailable nutrients and phytoplankton in the overlying water to the surface of the bottom sediment.

b. Reaction (solubilization) from particulate species to dissolved species by biological degradation and desorption.

c. Adsorption of available phosphorus in the pore water onto the solid

sediment phase.

The ecological model proposed in this study is a 12-layer model in which

Lake Yunoko is divided into 12 horizontal slices along the depth of water at

1-m intervals. There are two sediment submodels, i.e., sediment A represents

the bottom sediment of the littoral zone, from 0 to 4 m, and sediment B corresponds to the profundal zone, from 4 to 12 m. Each submodel is divided into

20 layers from the surface with intervals of I cm.

MODEL FORMULATION AND CALCULATION

Figure 4 shows a flow diagram for the ecological model. The system of

differential equations and adjunct equations (not shown here) to define this

model containing ecological processes and processes of interactions between

sediment and water is constructed based on the concept shown in Figure 4.

Field data from Lake Yunoko and laboratory data using sediments of Lake

Yunoko were used extensively to evaluate parameters in the model (Hosomi

et al. 1984). When sufficient information was not available, the literature

(Nyholm 1978, Jorgensen 1979, Scavia and Robertson 1979, Matsuoka 1984) was

also consulted to provide a range of values for the parameter.

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

solve the system of differential equations (HITAC M-280H, Computer Center,

National Institute for Environmental Studies). The period of numerical calculation is from I May 1979 to 1 December 1982. Forcing functions are weather

(Nikko Meteorological Station, near Lake Yunoko), volume and temperature of

inflows, and inflow concentrations of nutrient and dissolved oxygen (daily

data obtained by interpolation of observed data (Hosomi et al. 1984)). Observed values on 1 May 1979 were used as initial values of state variables in

the model.

189
START

READ min//al values

READ 1iput dole . weather, inflow a

quoaity, coefficients

READ ouoput of woler temperafure model

water a temperature, vertlical

advection and diffusion Figure 4. Flow diagram for the

NEXT I ecological model TITME

STEP CALCULATE C It +,' verfical

advection and diffusion

CALCULATE Ctl+4aI) production,

grazh7g, decay edc.

C concenflrf/on Of aboIc

and biotic constituent

IOUTPUTI

ISTOP

MODEL CALIBRATION

The outputs of the water temperature model are shown in Figure 5. Good

agreement exists between the model calculations and the measured profiles of

water temperature. The water temperature model seems to simulate the phenomenon of ice covering and melting very well.

Figure 6 shows the results of simulation runs by the ecological model.

Most of the calculated values are in reasonable agreement with the observed

data. However, the ecological model could not simulate observed chlorophyll-a

concentrations, which scattered widely during short terms in the summer stagnation period. Sinking velocities estimated from observed chlorophyll-a

concentration in water and sedimentation fluxes of chlorophyll-a obtained by

using sediment traps showed extensive variations during 1 week in summer. In

this model, the mean values of these sinking velocities were employed, so the

errors in averaging processes may significantly affect the accuracy of calculated curves. Further studies on the sinking processes of phytoplankton and

other particulate materials (detritus) would be necessary.

Hosomi, Okada, and Sudo (1985) reported that the nitrogen dynamics of the

upper layer (0 to 1 cm) of the sediment regulate the nitrogen transportation

between sediment and water. So, we compared calculated with observed particulate phosphorus and nitrogen in the surface sediment.

The calculated values of particulate phosphorus and nitrogen in the surface layer of the sediment ranged from 1.2 to 2.2 mg P/g and from 5.7 to

190
* ilS. * 035S * Oi3S.

1)- 1979. S. I CAL: 1979. 9) 5. 1979, 7.11 - CAL () 1979. 7.24 -AL.

12 2 12

t0- 1- 0 - ~ - 10 --

0 0 Y0

4 4

2- - 2 -- - 2 --

o 10jols 2 o 00 IS020 o s t1 Is 20

TEMP.( C) TEMP.( C) TEMP.(" C)

(U) 1980. 7.16 -CAL 1980. 7.30 -CA 1960. 0.21 -CAL.

12 12 - 12

'° 8f " ff s 6 6

TEMP. v" C )TEMP. V" C ) TEMP. 1" C)

0 0iS 83OiS. a iS

14 - -- 4 - -- 4 -

(9) 1981. 4. 6 CL (9) 1981. 4.28 - A. (U) 198,. 5.18 -CL 12 - 2 12

t0 - 0 10 a 

4 4j

30 0

0 $ IO is Y)0 0 o is 1 20 0 5 to Is 20

TEMP. C) TEMP. V C ) TEHP.(" C )

* Oi1S. * Oi3S. * Oi5.

1982. 4.17 CA (U) 1982. 9.10 -CA ) 192.10. 7 -CAL.

12-. - 12- ,- i2

10 - e -- 10 - -- 10 --

4 4 4

2 - - - 2 - 2

so Is 20 0 S 10 15 20 0 5 0 20

TEMP. V C ) TEHP. ( C ) TEP. ( C)

Figure 5. Profiles of water temperature in Lake Yunoko;

comparison of calculated -- )and observed

data (0)

191
0.04

0- 1 M

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.11 .12.1. 2. 3. 4. S. B. 7. e. 9. 10.11 .12.1. 2. 3. 4. S. S. 7. 8. 9. 10.11.12.1. 2. S. 4. S. 8. 7. 8. 9. 10.11.12.

0979 1980 1981 t982

2.00

1. 2. 3. 4. S. 5. 7. S. S. 10.11.12.1. 2. 3. 4. 5.95. 7. 8. 9. 101. 2.. 2.. 4. 5. 5. 7.85. 9. 10.11.12.1. 2. 3. 4. S.6S. 7. 0. S. 10.11 .12

1 979 1280 1961 1902

0.20

a, 0-I

1.2.3. 45.8 7.9 9.10.11 .12.1. 2. 3. 4.5..8. 7.80.9. 10.11.12.1. 2. 3. 4. 5.6S.7.B. 9. 10.J11.12.1. 2. S. 4. 5. 6. 789 01.2

1979 1980 1991 1982

15.00

0- 1

12.3. 4.S. 6. 7.6S.9. 10.11.12.1. 2. 3. 4. 5.86.7.8.9S. 10.11.12.1. 2. 3. 4. S.8. 7.8e.9. 10.11.12A.1.2. 3. 4S. 50. 7.8.9 l0.11.12.

1979 1980 1961 1962

a. 0-1 m

Figure 6. Chlorophyll-a, available nitrogen, available phosphorus, and

dissolved oxygen concentrations in Lake Yunoko; comparison of

model calculations (---) and observed data (ED) (Sheet 1 of 3)

192
0.04

s- 6 m

2.00

1. 2. 3. 4. 5. 6. 7. 0. 9. 10.11.12.1. 2. 3. 4. S. 6. 7. 8.9S 1. 01.22 -.--. .3 .. 8 .8.S. 02.1..2 6. 7.a 89. 0..2'

1979 1980 1982 2982

5-5 6

.23. 4.5S.6S.7.8.90. 10.11.12.2.2. 5. 4.S. 6.17.80.9. 10.11.12.1.. 4 S. .6. 7.8.6. 2. 0.11.12.1.2. 3. 4. 56. 7.5.90. 10.11.12

1879 2900 1681 2882

5-824

1.2 .4 S. .8 .8 2. 3. .2.21.. 4 10.21.12.1. 7. 9. S. 6. 8. 2. 3. 4. 8.7.. 9. 10.11.12.1.2.3 .50 .89 02.2

t979 2980 IS82 2962

b. 5-6m

Figure 6. (Sheet 2 of 3)

193
0.04

10-1l I

1.2. 3. 4.S. 6. 0.6.S. 10.11.12.1. 2. 3. 4.S.6S.7. S.9. 10.11.12.1. 2. 3. 4.S. 6. 7.6S.9S. 10.11.12.1.2. 3. 4.5S.6S. ?.S.9. 10.11.12.

1979 [960 1961 196?

2.00

1. 2. 3. 4. S. 6. 7. S. .10.A1 .12 .1 . 2. 3. 4. S. 6. 7. 6. S. 10.11t.A2.1. 23. A. 5. 6. 7.8a. 9. 10.11 .12.1. 2. 3. 4. 5. G. 7. 6.9S. 10.11.12.

t979 2980 2962 M92

0.20

I.2. S. 4. S. G. 7. 6. 9. 10.11.12.1. 2. 3. 4. 9.6S. 7. 6. 9. 5A10.21.2.1. 23. 4. S. 6. 7.6 9.9. 1.11..2 .4 .. 7 11.12'

1979 2960 1901 12962

I5.00

1. 2. S. 4. S.6.. 6. 9 01.2.1. l A 2. 3. 4. S. 6. 7. 9. 9. 10.112.12.1. 2. 3. 4. 5. 6. 7. 6.9S. 10.11.12.1. 2. 3. 4. . 67 7.S 6 9 . 01.12. ~ 1979 1960 1961 2962

c. 10-11 mn

Figure 6. (Sheet 3 of 3)

1.94
9.0 mg N/g, respectively. These ranges were within observed values of particulate phosphorus and nitrogen in the surface sediment (0 to 2 cm or 0 to 3 cm

layer), i.e., 1.7 to 2.2 mg P/g and 6.0 to 7.2 mg N/g, respectively.

The calculated particulate nutrients in the first layer were inclined to

decrease from 1979 to 1982. But, observed data in the surface sediments were

approximately constant within the range of sampling and analytical errors.

The inconsistency may be derived from the errors in calculating sedimentation

flux of phytoplankton in model calculation.

Table 1 compares model calculations and observed data on phosphorus and

nitrogen release flux from bottom sediments during summer stagnation periods

in Lake Yunoko. The agreement between the model calculations and the measured

data was good.

TABLE 1. RELEASE FLUXES OF PHOSPHORUS AND NITROGEN FROM BOTTOM

SEDIMENTS DURING SUMMER STAGNATION PERIODS IN LAKE

YUNOKO

Values Estimated from Nutrient

Release Experiments Calculated Values

Min. Max. Average

Phosphorus Release Flux, mg P/m 2 /day

1979 4.0 6.8 6.6

1980 3.6 6.5 4.8

1981 0.4 2.4 2.3

1982 0.2 1.9 1.4

Nitrogen Release Flux, mg N/m2 /day

1979 56 60 43

1980 45 32

1981 28 71 27

1982 20 44 27

Phosphorus removal of wastewater began in 1981 (only summer and autumn

season). The total phosphorus concentration in the euphotic zone decreased

from 0.052 mg P/1 (1979) to 0.036 mg P/1 (1982). However, chlorophyll-a

concentration in the euphotic zone remained constant at about 20 pg/i.

Hosomi, Okada, and Sudo (1986) considered that this inconsistency was derived

from the fact that the limiting nutrient for phytoplankton growth changed from

nitrogen (before treatment) to phosphorus (after treatment) as a result of

reduction of phosphorus loading.

The simulation demonstrated that the available phosphorus concentration

in the epilimnion decreased to below the detection limit after phosphorus removal (Figure 6) without any remarkable reduction of chlorophyll-a concentration. Thus, the results of simulation seem to be consistent with those of the

observation by Hosomi, Okado, and Sudo (1986).

195
ASSESSMENT OF EUTROPHICATION CONTROL PROGRAMS

The effectiveness of eutrophication control programs on chlorophyll-a and

dissolved oxygen concentrations was evaluated by using the ecological model

developed in this study. Sediment dredging, artificial circulation, and reduction of external loading as eutrophication control programs were evaluated

taking forcing functions in 1980.

Initial values were assumed to be zero in sediment dredging simulation;

i.e., there were no available nutrients and biodegradable particulate nutrients in sediment after dredging. Sediment oxygen demand was reduced to

half by dredging. The same values as those in the control simulation were

taken for other parameters.

In the case of artificial circulation, eddy diffusion coefficients in the

water temperature model were increased from 0.005 cm2 /sec in the control simulation to 1.0 cm2 /sec. Other parameters and conditions were the same as in

the control simulation.

In the reduction of external phosphorus loading, phosphorus loading from

the wastewater treatment plant was reduced to half or zero.

Figure 7 shows variations with depth and time of water quality constituents in the control simulation, sediment dredging simulation, artificial circulation simulation, and reduction of external phosphorus loading simulation.

In the sediment dredging simulation, annual average chlorophyll-a concentration in the surface water (0 to 4 m) decreased to 72 percent of that of the

control simulation. The steep increase of available phosphorus toward bottom

sediment diminished because nutrient release flux from bottom sediment became

small. As a result, a peak in chlorophyll-a concentration in the surface water during the autumn circulation period did not appear. However, dissolved

oxygen in the bottom water (10 to 12 m) during the summer stagnation period

was scarcely restored by dredging.

A dredging case simulation was conducted with the sediment oxygen demand

reduced to zero; for this case, dredging elicited the augmentation of only

1 mg/1 dissolved oxygen concentration (from 2.3 mg/1 to 3.3 mg/t). Accordingly, oxygen demand by sediment may have little effect on oxygen depletion in

the bottom water during the summer stagnation period.

Artificial circulation changed the vertical profile of water temperature;

i.e., uniform temperature was noted from the surface to the bottom, along with

an increase in bottom water temperature of about 50 C. Dissolved oxygen concentration in the bottom water during the summer stagnation period increased

from 1.9 mg/i (control simulation) to 7.2 mg/i. However, chlorophyll-a concentration in the surface water scarcely decreased when compared with the control simulation, and chlorophyll-a in the water column increased.

A 50-percent reduction in external phosphorus loading decreased

chlorophyll-a concentration in the surface water in the summer to 82 percent

of the control simulation. During the circulation in early autumn, the

196
AV-P (Jg/I) AV-P (0g/I) 0- 0-

IL L

10 10 10 L

• 50 0

o a I 

A 10 10

12- 12- H 0 

ChI.D (mg/I) ChI. (Pg/I)

0- 0- 300 20O~

r /%N.dý20

L 10 20 20 10 1 10 10

2 102 ,J M, AIM Ji , M

____ ___ ___ ___ I L 12. IT l 12-

D 0 (mg/i) 0 0 (mg/I)

0- 0-

H 

E 12 12 10 10 " 12 H> 12 10D

12 _______________ 12- kL.

12 J,,M, A.M 1 J.J,,A aSi 0,N.Di iJF,FM.AM,JJAS,O,ND01

a. Control b. Sediment dredging

Figure 7. Variations with depth and time of water quality constituents

in the control simulation, sediment dredging simulation,

artificial circulation simulation, and simulation of reduction

of external phosphorus loading (Continued)

197
AV-P (•g/I) AV-P (Wg/I)

0- ~0- -

" L L -10 10

10 10 10 1

12- 11-0

ChI.a (pg/I) ChI.s (pg/I)

0- 2 V 10- r- VP~

IH 2021 2'(Oof 10 20 20 10 i I-Pwv

0 Z 1 10 10

iCi 10 N

12-- 12

0 0 (mg/I) D 0 (mg/I)

10 E /

o LS

12- N 112

lJiFMAM,.J,JA,S,O,N 3 Dj LJ,F.M.AM, J J,A,SO 1N0D

c. Artificial circulation d. Reduction of external

phosphorus loading

Figure 7. (Concluded)

198
calculated chlorophyll-a values were the same as those in the control simulation. This result was attributed to the transport of nutrients released from

bottom sediments toward the epilimnion by autumn circulation.

Phosphorus loading from wastewater was reduced to zero, and annual average chlorophyll-a in the surface water decreased to 52 percent of that of

the control simulation. From the chlorophyll-a concentrations in the surface

water it was noted that the effectiveness of phosphorus reduction was the same

as that of sediment dredging.

CONCLUSIONS

An ecological model of Lake Yunoko, a dimictic lake, was developed to

assess various programs for eutrophication control with special emphasis on

management of the bottom sediment. A multicomponent dynamic model for nutrients in the bottom sediment-water system was incorporated into the ecological model.

Good agreement was noted between the model calculations and observed nutrients, chlorophyll-a, and dissolved oxygen concentrations in the water and

nutrients concentrations in the bottom sediment. The agreement between the

model calculations and the measured nutrient flux from bottom sediment during

the summer stagnation period was good.

The effectiveness of eutrophication control programs on chlorophyll-a

concentration in the surface water and dissolved oxygen concentration in the

bottom water was assessed using the calibrated model. Sediment dredging decreased nutrient flux from the bottom sediment. As a result, the peak of

chlorophyll-a concentration in the surface water at autumn circulation period

did not appear. However, the depletion of dissolved oxygen in the bottom

water during the summer stagnation period was scarcely restored by dredging

only.

Artificial circulation increased dissolved oxygen In the bottom water

more than 7.2 mg/I throughout the year, whereas chlorophyll-a concentration in

the surface water scarcely decreased when compared with control simulation.

A 50-percent reduction of external phosphorus loading could not decrease

the peak of chlorophyll-a concentration during early autumn circulation. It

did decrease chlorophyll-a concentration in the surface water during the

summer.

REFERENCES

Chen, C. W., and Orlob, G. T. 1975. "Ecologic Simulation for Aquatic Environments," System Analysis and Simulation in Ecology, Vol 3, B. C. Patten,

ed., New York Academic Press, Inc., pp 475-588.

Environment Agency, Government of Japan. 1985. Quiality of the Environment in

Japan 1984.

Greene, G. M. 1981. "Simulation of Ice-Cover Growth and Decay in One Dimension on the Upper St. Lawrence River," NOAA Technical Memorandum ERL GLERL-36,

PB82-114208.

199
Gulliver, J. S., and Stefan, H. G. 1982. "Lake Phytoplankton Model with

Destratification," Journal of the Environmental Engineering Division, American

Society of Civil Engineers, Vol 108, pp 864-882.

Hosomi, H., Okada, M., and Sudo, R. 1985. "A Model of Nitrogen Release from

Bottom Sediments," Management of Bottom Sediments Containing Toxic Substances,

Proceedings of the 10th U.S./Japan Experts Meeting, T. R. Patin, ed., US Army

Corps of Engineers, Water Resources Support Center, pp 30-62.

Hosomi, M., Okada, M., and Sudo, R, 1986. "The Effects of Wastewater Phosphorus Removal on Lake Yunoko," Journal of Japan Sewage Works Association,

Vol 23, pp 52-61.

Hosomi, M., Okada, M., Yagi, 0., Yamane, A., and Sudo, R. 1984. "Eutrophication in Lake Yunoko," Research Report from the National Institute for Environmental Studies, Japan, No. 56.

Huber, W. C., Harleman, D. R. F., and Ryan, P. J. 1972. "Temperature Prediction in Stratified Reservoirs," Proceedings of American Society of Civil Engineers, Journal of Hydraulics Division, Paper 8839, pp 645-666.

Hydrologic Engineering Center. 1974 (revised 1978). "WQRRS, Generalized Computer Program for River-Reservoir Systems," User's Manual 401-100, LOOA,

US Army Corps of Engineers, Davis, Calif.

Imboden, D. M., and Gachter, R. 1978. "A Dynamic Model for Trophic State

Prediction," Ecological Modeling, Vol 4, pp 77-98.

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

Modeling, Vol 2, pp 147-165.

Jorgensen, S. E. 1979. Handbook of Environmental Data and Ecological Parameters, Pergamon Press.

Larsen, D. P., Mercier, H. T., and Malueg, K. W. 1973. "Modeling Algal

Growth Dynamics in Shagawa Lake, Minnesota, with Comments Concerning Projected

Restoration of the Lake," Modeling the Eutrophication Process, E. J.

Middlebrooks, D. H. Falkenborg, and T. E. Maloney, eds., Utah Water Research

Laboratory, pp 15-32.

Matsuoka, Y. 1984. "An Eutrophication Model of Lake Kasumigaura," Research

Report from the National Institute for Environmental Studies, Japan, No. 54

pp 53-242.

Mori, S., and Yamamoto, G., eds. 1975. "JIBP-PF Research Group of Lake

Yunoko; Productivity of the Community in Lake Yunoko," JIBP SYNTHESIS

Productivity of Communities in Japanese Inland Waters, pp 47-105.

Nyholm, N. 1978. "The Use of Management Models for Lakes at the Water Quality Institute, Denmark," State-of-the-Art in Ecological Modeling, Vol 7,

S. E. Jorgensen, ed., pp 561-577.

200
Orlob, G. T. 1983. "One-Dimensional Models for Simulation of Water Quality

in Lakes and Reservoirs," Mathematical Modeling of Water Quality: Streams,

Lakes, and Reservoirs, G. T. Orlob, ed., International Series on Applied

System Analysis, John Wiley and Sons, pp 227-273.

Scavia, D., and Robertson, A. 1979. Lake Ecosystem Modeling, Ann Arbor

Science, p 326.

Smayda, T. J. 1964. "Some Experiments on the Sinking Characteristics of Two

Freshwater Diatoms," Limnology and Oceanography, Vol 10, pp 499-510.

Titman, D., and Kilham, P. 1976. "Sinking in Freshwater Phytoplankton. Some

Ecological Implications of Cell Nutrient Status and Physical Mixing Processes," Limnology and Oceanography, Vol 21, pp 409-417.

Tochigi Prefectural Government. 1978. "Report of the Effects of Lake Sediment Dredging on the Water Quality in Lake Yunoko," Tochigi Prefectural Association of Pollution Controls and Managements.

Water Resources Engineers, Inc. 1969. "Mathematical Models for Prediction of

Thermal Energy Changes in Impoundments," US Environmental Protection Agency

Water Pollution Control Research Series 16130 EXT, Contract 14-22-422, US

Government Printing Office, Washington, DC.

201
Uo

NEW TECHNOLOGIES APPLIED AT MEINOHAMA LANDFILL

-HM. Tajiri, H. Sekiya

Japan Bottom Sediments Management Association

Q ABSTRACT

The landfill work which reclaimed an area of

74.0 ha at the Meinohama coastal area in Hakata Harbor

W was conducted in 1982-1985 by the Hakata Harbor Devel01 gopment Company. Several new technologies were apco plied, the most noticeable being the application of a

new landfilling method characterized by placing

___• dredged material in a pond with two to three staged

intervals between placements. In this manner the I __ dredged material is allowed to stabilize through selfCV weight consolidation during the intervals between

placements.

New technologies were also adopted for spillwater

treatment and dredged material dewatering.

This paper deals with the results of these

technologies.

LANDFILL SITE

The landfill site (Figure 1), Meinohama, is on the western side of Hakata

Harbor and has a total area of 74.0 ha. The reclaimed land will be used

mostly for residences and other uses such as parks, roads, and port

facilities.

PROPERTIES OF FILL MATERIAL

The properties of the fill material are represented by the triangular

diagram (Figure 2) and the Casagrande plasticity chart (Figure 3). The fill

material consists of sandy loam and clay. In the plasticity chart, the liquid

limits lie between 30 and 60, and the plasticity indexes between 10 and 30.

Since these points lie above the A-line, as a general rule the material is

normally considered to be inorganic and is therefore suitable as fill material.

DREDGING

The dredged area is located about 500 m from the reclaimed land and has

an area of 370,000 m2 (Figure 4). The silty material in the upper layers of

the sea bottom was dredged mechanically and was placed onto the pond bottom.

The sandy material in the deeper layers was dredged hydraulically and deposited upon the previously deposited silty material (Figure 5). The boring profiles from the dredged area are shown in Figure 6.

202
Heinohama ,

Figure 1. Landfill site

Figure 2. Triangular diagram

2Silt

203
so

______ 14

kT"!f"ig cow IJ9Wb ~ i

0.S

/ . 60 o s 1 0 IV x co

iquif WAd IW,

Figure 3. Casagrande plasticity chart

955

areasa

DvLadfged AraAl

C'm'

-J ~ =955

Thgue 4.Disposed materialfin te pn ssbetdt cnoiainb t

2044
" ~~Sand •-•N uz

SitGrab Hydraulic

Figure 5. Dredging methods

Boring Pristman Surveyed by Drivers

m In =

- 6.0-

Silt

- 7.0 Silt

Siit

- 8.0- Sand

- 9.0- Sl

-10.0 Clay Clay

Clay

-11. Sand Sand

S~~Sand

-12.0 Gravel

Sand Sand

•-13.0- Gravel Gravel

Dredged -14.0--.

"15. 14.7m

-15.0"

Figure 6. Boring profiles

205
"z

0

Figure 7. Self-weight consolidation

The total load acting on the slice layer AP at the height of Z in

Figure 7 is represented as follows:

AP = (H- h)yw + (h - z)y' (1)

where Yw = unit weight of water

y = unit weight of wet dredged material

s

The settlement of the slice layer AS becomes

AS = U m AP dz (2) v

where

U - degree of consolidation

mv = coefficient of volume compressibility

Then the settlement for the disposed height h is

h

AS f U m AP dz (3)

0

The coefficient of volume compressibility m can be approximately

represented by the following hyperbolic function

m - AAPn (4)

where A and n are curve fitting constants. Then we have

206
h

S - f U AAPnAP dz

0

h

= U A f UPn+l dz

0

h

- U A f [(H- h)Y + (h - Z)Ys]dz

0

,n+l H n+2 n+2

=U ns 

n I -)+- - I -j(5) + 2HHn+ 2 H YS

The m curve is shown in Figures 8 and 9.

cma/kg

0.4 -" -

0.3-

0.21

in 0.1 2

0.011 , ,, 005 0.1 AP 05 1.0 2D kg/cm2

Figure 8. m versus AP (October 1984)

If we put

f(h) [ - ) + -]+2 - -(]

207
cm2 /kg

020

0.18

0.1

v 0.14- m -0.047 AP -0.4082

0.10 V

0.08

006

004 0 0

002

0 02 0.4 0.6 0% 1.0 1.2 1.41 1.6

AP kg/cm2

Figure 9. Approximated curve of m

Equation 5 becomes

, n+2 n+2

S ' sU . h (7)

ShfUA n+2 fH

As Figure 10 shows, the function of (h/H) can be approximated as follows:

h h (8)

060

10 1,

040-

/

02-

02 0.4 0.6 0.8 1.0

Finally, we have

Ay n+2 Hn+2

n n+2 H

208
This is a settlement equation of dredged material disposed in water.

DEGREE OF CONSOLIDATION

The coefficient of consolidation c can be approximated by the

following hyperbolic function:

c = BAPm (10)

The curve of c can be seen in Figures 11 and 12.

cm 1/kg

20

Cv

500-.

0.05 0.1 0.5 1.0 2.0 4.0 cm2 /kg

Figure 11. cv versus AP (1984)

kg/cM

2

100.

800 - 553 Ap-0.237 C v 0. v'.

600,

40

200

0 02 O 0.6 0. 1.0 1.2 1A kg/cm2

AP

Figure 12. Approximated curve of c

209
The mean value of c for dredged material disposed in the water is

calculated as follows: V

h

cv f BAP(z) m dz

h

0

h

= f B [(H - h)yw + (h - z) y'j] dz

Os

0

________ m1m1 

1 h wj . +11) -(mn + 1)y'h [(1 )T. +/] -w T ()

If we put,

m+1 m+1

g 1 - w- + h - - -- (12)

Ys Y;

we have

By Nsnt+1 h

C = 5 (13) v (m + 1)h

The function of g(h/H) (Figure 13) also can be approximated as follows:

g ) h (14)

Then Equation 11 becomes

By.'____ h B (yIH) M

Cv (m + 1)h XR m+1 (15)

If we represent the filling rate as a (Figure 14), the fill height h

becomes:

h - at (16)

210
1.0

Q8

0.3

0.4 Figure 13. Plot of g(h/H)

0.4 versus h/H

0.2 M- -0.256 0.2- / "

iI I I I

0.2 0.4 0.6 0.8 1.0

h < h-at

h

h Figure 14. Filling rate, a

"ho

at

At the point of time when the fill height reaches h , the consolidation

acts on the fill material during dt . Then we have the following time factor:

c dt

dT = v (17)

(at) 2

where T is the time factor. Then

t c

T=f cv dt

0 (at) 2

00<'

(18)

a 2 \L /

211
When the fill height is small, it is presumed that no consolidation occurs.

The time when the consolidation begins is assumed to be t 0

0

PLACEMFNT OF DREDGED MATERIAL

The landfilled area was divided into 28 sections as Figure 15 shows.

Each section was filled in such a way that the dredged material was placed in

two to three stages with inactive intervals between placements. For example,

Figure 16 shows the two-staged placement conducted at C-section. The first

placement height was 2.275 m and the disposal rate was 9.89 cm/day, for

23 days. After placement, an inactive interval of 42 days was provided.

After day 65 the second placement commenced with a rate of 2.66 cm/day. After

111 days, the height of the deposit reached the appointed level of 3.5 m.

Figure 17 shows the three-staged filling diagram for the P-section. The objective of the inactive intervals was to allow self-weight consolidation of

the dredged material to occur. Therefore, the multistage disposal method is

presumed to promote the stabilization of the material.

r i

' L -, ---E-2 MG'

"GcT

L

Figure 15. Division of pond area

m

4.0

3.0'

2275 265 a2.66cm/day

000) 2.0

-4 4 am 9.89 cm/day -4

,LA 1.0 /a-=-.9.89 cm/day C-Section

0 20 40 60 80 100 120 day

Time

Figure 16. Fill diagram of C-section

212
m

41"

3O a- 4.21 cm/day

232 71 11JV

-H

420

a a- 4.3 cm/day

21. 41 P-Section

a-4.29 cm/day

20 40 60 80 100 120 140 day

Time

Figure 17. Fill diagram of P-section

Figure 18 shows the settlement curve calculated by Yoshida's equation described on page _. Figure 19 indicates the change in degree of consolidation

during disposal of the dredged material. From Figure 19 it can be seen that

the consolidation advances considerably in spite of the presence of water,

primarily due to the slow disposal rates a of this method. It is presumed

that the degree of consolidation reaches 80 percent at the completion of

filling.

Time

0 20 40 60 __ gg day

2 Disposal ast 

.

4 -

I0 o. 6

8-- 2nd Disposal

10ý

cm

Figure 18. Settlement of disposed material

213
1.0 Consolidation Interval

K--i Total

S0.6 

- o

n / Upper Layer

o /

U Lower Layer I S0.4 

oI j

II lI I II

0 20 40 60 80 100 120 days

Time

Figure 19. Degree of consolidation versus time

4j3.0 '3. 0a-4.21 cm/day

7 72

~2.0-

M a- 4.29 cm/day

0

0. W, _03 24 41 .-H 1.0-

z • aP-Section

a- 4.3 cm/day

20 40 0 80 100 12 140 day

Time

Figure 20. Three-stage disposal

Figure 20 shows the three-stage disposal conducted in P-section. In this

case the disposal rate was about 4.3 cm/day with inactive intervals of 17 and

48 days. Figure 21 shows the calculated settlements in P-section. Figures 22

and 23 show the degrees of consolidation.

In this case, it is presumed that the degree of consolidation reaches

0.94 at the completion of filling.

The consolidation states of the material placed by the various filling

methods are compared in Figure 24. It is evident that the consolidation state

of fill material differs for the different filling methods. The settlement

resulting from placement of material in three stages is the largest, and that

resulting from single-staged placement of material is the smallest. There is

214
Time

0 20 40 60 80 100 120 140 160 days

Sta -' 17 days

2- P-Section

2nd Stage 41

,e 4

C-Section -,S6 

10 .- 3rd Stage

10-

12Cm

Figure 21. Settlements of three-stage disposal

1.0

0.8 . lst Stage

Q6 - 3rd Stage U

0.4

0.2

20 40 60 80 100 120 140 160 days

Figure 22. Degree of consolidation of each stage

215
1.0

0

"*0

oW 0.6

0

U

0 0.4

2 SQ 

0 20 40 60 80 100 120 140 days

Time

Figure 23. Degree of consolidation of the

entire deposit

Settlement

0 2 4 6 8 10 12cm

11.05 Three-Stage Disposal

9.86 Two-Stage Disposal

/ ////A629 Single Disposal

Degree of Consolidation

o0 2 0. 06 0.8 10

0.94 Three-Stage Disposal

0.8 Two-Stage Disposal

I 0.767 Single Disposal

Figure 24. Comparison of various disposals

216
a difference of 4.76 cm between them. For the single-stage method to attain

the same settlement as the three-stage method, it is necessary to apply larger

cover loading than that of the three-stage method (Figure 25).

AHc -,j/

"Cover.

,over HC

AS

Filled Material I Filled Material

Y , s

Multi-Stage Method Single-Stage Method

Figure 25. Difference in cover thickness

according to methods

If the cover height necessary to yield settlement AS of filled material

is represented as AHc , we have the following equation:

I

AHc AS n+- (19)

Y' IczAHsJ

If we put the following numerical values in Equation 19

A = 0.0578 cm2 /kg

n = -0.31

AS = 4.21 cm (average difference)

Hs = 350 cm

Y' = 0.00165 kg/cm3

s

we get

1

1 4.21 - 58.86 cm •c = fHc 0.00165 1 xx0.0578 x 350) 5

Therefore, the increment of cover volume becomes

AV = 0.5886 m x 716,000 m2 = 421,438 m3

If we assume a covering cost of $17/m 3 , the total cost of $7,164,446

($17/m 3 x 421,438 m3 ) would be saved by using the new method. Consequently,

we can say that the merits of the new method are great.

217
SPILLWATER TREATMENT

The settling pond was divided into four sections with three interior

spillways and one final spillway (Figure 26). These spillways were arranged

so that spill water would flow as long a distance as possible, thereby increasing retention time of the slurry. The longer the passage, the stronger

the sedimentation. When the dredged material was poured into A-section, the

SS concentrations of spill water at SR 3 were about 2 to 4 mg/i due to a long

distance of more than 500 m. However, when the pouring point moved to

B-section and then to C-section, the SS concentrations were 11-15 mg/i and

about 100 mg/i, respectively. In this study, the permissible SS concentration

of spill water at the final spillway, SR4 , was less than 50 mg/i. In order

to attain this safely, it was necessary to treat spill water at the final

spillway.

SRR4

ISRS

Figure 26. Spillways

Figures 27 and 28 show the construction of the final spillway. After

operation began, it was discovered that a normal settling pond was insufficient to reduce the concentrations of spill water to the desired level of

50 mg/i. Therefore, two fibrous sheets were added as an improvement. The

main sheet was an unwoven textile for filtration, and the supplementary sheet

was a permeable textile to prevent access of solid material settled on the

pond bottom. These geotextiles gave good results.

DEWATERING TESTS OF DREDGED MATERIAL

When dredged material is placed into a pond from a delivery pipe (hydraulic pipeline), the coarse-grained material settles out near the point of discharge while the fine-grained material settles at some distance from the pipe

(Figure 29). This fine-grained material often remains very wet. In order to

overcome this problem, dewatering tests were performed using drainpipes.

At the bottom of a pond having an area of 52 x 48 = 2,496 m2, 14 drain

pipes (1500) were placed. The water which drained from the overlying dredged

material was gathered in two colgates and pumped up to the ground (Figure 30).

218
Textile for Filtration

Supplementary Sheet

A:

"I -

• :: :....'-. : :

=777777+77ý777Y77777

Figure 27. Vertical section of final spillway

Sea

Settling Tank

130x50 -6000 m2

18m I

2m

Figure 28. Plane figure of final spillway

Remaining Water 1 _•

Silty

Figure 29. Undewatered silty material

219
. Dredged Material%.

Colgate

14 Drain Pipes

A = 52 x 48 = 2,496 m2

Figure 30. Drain pipes for dewatering

The water content of the dredged material at the test area was 62.7 percent, which corresponds to a total quantity pore water of 3,895 m3 . This system drained 972 m3 of water. Therefore, the dewatering efficiency became

972 -0.25

3,895

This means that the initial water content of 62.7 percent was reduced to

47 percent.

CONCLUSIONS

Several new landfilling technologies were introduced and applied at

Meinohama. The new filling method was the first attempt in our country. It

was found that they were beneficial from both a technical and economical viewpoint. It is worthwhile to note that these technologies have contributed to

the improvement of reclamation techniques.

220
The total load acting on the slice layer AP at the height of Z is

represented as follows:

AP = (H - h)yw + (h - z)ys

where

ys = saturated unit weight of soil mass

or

AP - (H - h)y + (h - z)y' w 5

where

y= effective unit weight of the soil mass S

S's - Yw

The effective load is

AP'(or a') - (h - z)y's

This effective load is the one and only load which causes consolidation. The

load caused by the water does not cause consolidation.

According to our sources (References attached), degree of consolidation

is identified as a U . In addition, settlement AS is calculated by the

following equation

AS - m AP dz

v

As you will notice, degree of consolidation is not used in the settlement

calculation. It should also be noted that AP in the above equation should

be the effective pressure, not the total pressure. Therefore AP used in the

above equation should be calculated as follows:

AP - (h - z)y'

It should not be calculated as shown

AP - (H - h)y + (h - z)y' w s

References for settlement equation:

Terzaghi, K. 1943. Theoretical Soil Mechanics, John Wiley and Sons, Inc.,

New York, Article 102, p 281.

Terzaghi, K., and Peck, R. B. 1967. Soil Mechanics in Engineering Practice,

John Wiley and Sons, Inc., New York, Article 41, p 278.

221
THE ROLE OF MICROORGANISMS IN MOBILIZATION

OF CONTAMINANTS FROM SEDIMENT

COD. Gunnison

G •Environmental Laboratory

US Army Engineer Waterways Experiment Station

Vicksburg, Mississippi 39180-0631

c and

L. K. Blum and A. L. Mills

Department of Environmental Sciences Q _ - University of Virginia

__ Charlottesville, Virginia 22903

ABSTRACT

This paper describes the results of a literature

survey on microorganisms and their ability to enhance

the movement of contaminants from sediment into the

overlying water. The sediments included in this discussion are from both subaqueous and wetland environments. The survey is specifically concerned with the

role of microorganisms in several processes occurring

in flooded soils and sediments; these processes include: formation of dissolved organic matter, both

directly from nutrients in flooded soils and sediments

and from living and dead plant and animal tissues; incorporation and/or conversion of contaminants into

dissolved organic form; and transformation of contaminants that enter flooded soil or sediment systems from

an external source, such as tides, floodwaters, and

overland runoff. This information is used to assess w the importance of dissolved organic matter as a vehi-

! - cle for transport of total organic matter and organic

pa contaminants away from flooded soils and sediments.

=- Special attention is given to the importance of microorganisms in the formation of dissolved organic matter

and the transformation of contaminants into soluble

form.

INTRODUCTION

This paper is based on a literature evaluation conducted for the US Army

Engineer Waterways Experiment Station by Blum and Mills (1986). Other information has been used, where appropriate, to provide clarity.

Sediment and its microbial inhabitants collectively provide many of the

biological, chemical, and physical properties necessary for the processes of

222
mineral cycling and the degradation of man-made chemicals. Sediment is a

multifaceted interface--between solid and liquid, between aerobic and anaerobic, and between sorptive and desorptive. Depending upon hydrodynamic conditions in the overlying water column, sediment may serve as a source or sink

for contaminants in the ambient environment (Gunnison, Engler, and Patrick

1985). In addition, microbial activities in sediment may, in large part,

determine what chemical constituents are released into or removed from the

overlying water column (Brannon, Chen, and Gunnison 1986; Gunnison, Engler,

and Patrick 1985). Thus, activities of microorganisms can often serve as major determinants of water quality.

Wetlands are special sediment environments, serving as transitional interfaces between aquatic and terrestrial habitats and often sharing commonalities with both systems. In the past these intermediate zones were considered

to be useless wastelands that offered benefits only to sportsmen, and the

principal use of these regions was achieved only by drainage to provide available land for agriculture, urban, or industrial development. While loss of

wetlands to such activities is still occurring, the rate of this loss is decreasing, largely in recognition that these areas are of value in ways not

previously recognized.

Increasing interest in interactions between aquatic sediment microorganisms and their environment is reflected by the number of recent papers dealing

with various aspects of this subject (Brannon, Chen, and Gunnison 1986;

Collins 1977; Gunnison, Engler, and Patrick 1985; Marshall 1980). The study

reported herein is concerned with the specific role of microorganisms in the

formation (or removal) of dissolved organic materials that complex with contaminants and alter their mobility, either increasing or decreasing release of

the materials from sediment. Many compounds form complexes with dissolved

organic materials, and the resulting complex may also be soluble, increasing

the mobility of the original compound of interest. In sediment, as in many

other aquatic environments, the activities of microorganisms can exert a

strong influence on the chemical status of the habitat. This influence may

involve direct action on the contaminant itself, or indirect action on material that may subsequently react abiologically with the contaminants.

For purposes of this paper, contaminants are defined as any chemical substance in an aqueous or wetland sediment that is undesirable with respect to

man's intended use of the sediment. Dissolved organic matter (DOM) refers to

those organic materials in solution which are small enough to pass a 0.1-um

filter.

NATURE OF SEDIMENTS AND FLOODED SOILS

Ponnamperuma (1972) has characterized sediments as substrates having dark

color; low redox potential; no dissolved oxygen, at least within the strata

underlying the first few millimetres or centimetres of its surface; reduced

forms of N, S, Mn, and C and refractory organic matter; and often, a thin,

light-colored oxidized layer at the surface. The composition of sediment

varies according to the source of the material and the hydrodynamic processes

occurring in the area in which the sediment settles. Those areas of the world

that have heavy industrial activity and/or large levels of harbor traffic are

223
likely to have sediments heavily polluted with organic and metallic contaminants. Many of these areas also require frequent dredging to keep the channels open to ship traffic.

Flooded soils differ from sediments in that they are flooded intermittently rather than permanently. A large variety of habitats contain flooded

soils or some type of wetland. These include the field flooded only briefly

during periods of heavy accumulation of precipitation, temporary pools and

riverbanks that are flooded for a portion of the year, tidal marshes that are

inundated on a daily basis, and rice paddies that may be flooded for months at

a time. As a habitat, the flooded soil may undergo comparatively pronounced

extremes in temperature and moisture during periods when the soil is not

flooded. When water is present over a soil, the depth is often fairly shallow. As a consequence, the water is easily mixed by the wind, and dissolved

oxygen levels are high. Shallowness also contributes to the ability of sunlight to penetrate the water column to the soil surface, supporting active

growth of algae and cyanobacteria. The level of organic matter can also be

high owing to the presence of rooted plants. These factors encourage the formation of a system with intensely reducing conditions in the underlying layers

and an oxidized surface layer. There is ample opportunity for chemical and

microbiological processes favored by these conditions to occur. Examples of

such processes include nitrification-denitrification, release of iron and

manganese in the reduced form, and sulfate reduction to sulfide (Gunnison,

Engler, and Patrick 1985). If the reduced forms of these materials are released into the water column, they may then be reoxidized; some are then reprecipitated on the sediment surface.

Flooded soil undergoing an accumulation of material and gradually rising

above the water level may evolve into a high marsh and then into meadowland.

The source materials for this process are often obtained from both aquatic

sediment and an admixture of living and decomposed organic material derived

largely from aquatic and terrestrial plants. In the case of newly filled reservoirs, a formerly dry or intermittently flooded soil surface undergoes a

transition associated with transformation of this substrate into an aquatic

sediment.

NATURE OF DOM PRODUCTION

Aquatic ecosystems typically contain large amounts of DOM relative to the

concentrations of particulate organic material (Vallentyne 1957; Wangersky

1965). In both marine and freshwater systems, the level of DOM is an order of

magnitude greater than the concentration of particulate organic matter (POM)

(Fenchel and Blackburn 1979; Parsons and Strickland 1962; Wetzel et al. 1972).

Freshwater concentrations of dissolved organic carbon under unpolluted conditions, for example, range between 1 and 30 mg C/1 (Wetzel 1983). DOM is derived mainly from two major sources: allochthonous sources through direct

input of organic materials such as autumn shed leaves (Kaushik and Hynes

1971), and indirect inputs of soil organic matter from overland flow and shallow ground-water inputs; and autochthonous sources such as cellular debris and

extracellular excretion products of aquatic organisms (Fogg 1958). Allochthonous DOM dominates most freshwater systems. In coastal regions, the carbon

levels vary from 0.1 to 100 mg C/1 (Menzel and Vaccaro 1964; Wilson 1961),

while in open ocean systems, the range is from 0.4 to 1.0 mg C/1 (Barber 1968;

Kerr and Quinn 1980). The relationship between DOM and POM is relatively

224
constant, with the POM concentration being an order of magnitude less than the

DOM concentration. The relationship of DOM to ecosystem productivity is unclear, due in part to the inability to reliably measure DOM turnover rates and

in part to the chemical complexity of DOM and the resultant difficulty in distinguishing between competing biological, chemical, and physical reactions,

such as POM formation. It is important to understand DOM before we can examine the interactions of this material with contaminants and understand the

consequences of processes occurring in aqueous and wetland sediments.

In most of the areas not dominated by man's influence, macrophytes and

some phytoplankton are responsible for-the production of most of the dissolved

organic matter. The amount of organic material that is excreted or exuded is

dependent on light, temperature, ionic composition of the medium, presence of

epiphytes, and conditions of the plant or type of plant. Generally, DOM release reaches a maximum during periods of intense photosynthetic activity.

Plant excretion can occur at the roots or from the foliage. DOM can also be

leached from foliage of emergent and terrestrial plants by rainfall and enter

water and, later, sediment. Submerged macrophytes exude DOM directly into the

water column, and from their roots and rhizomes into the sediment. Phytoplankton can also contribute significant amounts of DOM to wetlands. Large

amounts of DOM are also released by leaching and autolysis of plant tissues.

Information concerning the relative importance of DOM from macrophytes and

phytoplankton in wetlands is lacking.

While there are many origins of DOM, it appears that release of extracellular dissolved organic carbon by healthy primary producers is a major source

of dissolved organic carbon. Secretion of dissolved organic compounds occurs

in both freshwater and marine plants. Below-ground biomass of marsh plants

constitutes a significant portion of total organic carbon in wetland ecosystems. Estimates of the relative contribution of roots and rhizomes vary

widely. There appears to be a lack of suitable methods to determine live and

dead root and rhizome biomass. If wetland plants behave in a manner similar

to terrestrial plants, then the rhizosphere effect may be very important in

influencing the fate of contaminants in the root zone. The rhizosphere of wetland plants can include an oxidized zone in otherwise reduced sediments. The

Eh, pH, and biological and abiological reactions characteristic of sediments

would not be expected to occur in the rhizosphere. While it is known that

microbial biomass is elevated and activity is stimulated in the rhizosphere of

terrestrial plants, there appear to be few reports of microbial activity in

the rhizosphere of wetland and aquatic plants. Extensive investigations of

microbial processes in the rhizosphere of wetland and aquatic plants are required to determine what the reactions of importance are in that zone and what

contributions they make to the release of organic matter in the sediment.

Wetland plants, emergent and submergent aquatic macrophytes, and

phytoplankton are responsible for production of much of the highly labile DOM

found in sediments. Once DOM is produced, it may condense to form POM through

abiotic processes. Alternatively, the DOM may be assimilated by microbes and

incorporated into cell biomass, or it may be mineralized by microorganisms.

The proportion of DOM available for microbial assimilation is unknown and is

likely to be a function of the DOM source and the physical and chemical characteristics of the environment into which the DOM is released. Lush and Hynes

(1973) found that a large percentage of the leachate from autumn maple leaves

225
was converted directly to POM without microbial assimilation. This was dependent on pH and the calcium ion concentration. DOM that does not condense may

be available to microorganisms and may be quickly metabolized by microbial

assemblages found in association with plants and detritus.

The role of microorganisms in conversion of DOM to POM is just beginning

to be investigated as is the role of microbes in cycling of nutrients in wetlands through mineralization of DOM. The role of microorganisms is important

in production of refractory DOM and the alteration of the physical and chemical environment as a result of microbial metabolism of DOM. Studies have

shown that the amount of soluble microbiologically available organic material

present in marine sediments decreases with increased sediment depth (Seki,

Skelding, and Parsons 1968). Total organic carbon was observed to increase

with depth as a consequence of compaction and the accumulation of organic carbon resistant to microbial attack. The level of DOM in the pore water was observed to decrease sharply with depths below 2 cm. Results of other studies

suggest that turnover of fatty acids (Balba and Nedwell 1982) and mineralization of organic nitrogen (Abd. Aziz and Nedwell 1979) are detectable only

within the top 5 cm of the sediment profile. Even though the total organic

carbon content of the sediment was found to increase with depth, the proportion available for microbial metabolism decreased from about 1 percent at the

surface to less than 0.1 percent at 20-cm depth; at least part of this difference results from a decrease in pore water due to sediment compaction.

MICROORGANISMS AND CONTAMINANTS: DIRECT EFFECTS

Natural products, materials formed by plants, animals, and microorganisms, often comprise insoluble organic polymers, including aromatic macromolecules, which are unique in that only microorganisms have the required

enzyme complements for decomposition (Evans 1977). Although microorganisms

have evolved numerous enzymes to accomplish the degradation of natural products, tannins and lignins seem to decompose very slowly (Crawford 1981,

Dickinson and Pugh 1974). The degradation products of these two materials,

along with aromatic compounds, amino acids, proteins, and other materials that

result from microbial activities, are combined in a complex series of processes to form humus (Evans 1977). Humus is a persistent compound, but is

subject to continuous modification in soils. Aquatic humus is composed of

both water-soluble and particulate-sorbed components 'of terrestrial origin and

a component that may be formed in situ from degradation products of plankton

(Gjessing 1976). Little appears to be known about fate and effects of humus

in aquatic sediments.

Contaminants that are man-made xenobiotic compounds are often biotoxic,

readily bioaccumulated, and frequently move through food webs. Many xenobiotics, along with several of the aromatic petroleum hydrocarbons and petroleum

derivatives, are difficult to degrade. Degradation often depends upon the environmental circumstances. Degradation of aromatic compounds is frequently

accomplished by microorganisms utilizing one or more alternative pathways.

Aerobic and anaerobic catabolism of aromatic compounds has been reviewed by

Evans (1977), who gave special consideration to anaerobic dissimilation.

Among the pathways considered were anaerobic photometabolism of benzoate, anaerobic metabolism of benzoate through nitrate respiration, and methanogenic

fermentation of benzoate and other aromatics by a microbial consortium.

Xenobiotic compounds, especially the pesticides, often possess chemical

226
structures that interfere with metabolic processes. The basic chemical structure of many xenobiotics is similar to key biochemical intermediates; as such,

they are theoretically susceptible to degradation by some microorganisms.

However, addition (by man) of certain substituents, for example halogens, to

various positions on an aromatic structure can serve to increase to toxicity,

while simultaneously decreasing the degradability of the molecule. The latter

phenomenon occurs because the substituents shield the molecule itself from

enzymatic attack. As a consequence, the substituent group(s) must be removed

before biodegradation of many synthetic compounds can occur. Two other factors that inhibit biodegradation include competitive inhibition between microorganisms for growth factors and nutrients (Haller and Finn 1978) and diauxy,

the preferential metabolism of easily degradable compounds over other, more

refractory substrates (Atlas 1981, Chou and Bohonos 1979).

Microorganisms have an array of strategies for dealing with refractory

compounds. Certain strategies require the presence of several different members of a microbial community, rather than individual microorganisms. Evans

(1977) discussed several of these strategies, including cometabolism (Horvath

1972), enzyme induction, transfer of metabolic plasmids, a mutation that results in production of the requisite enzymes, and the formation of microbial

consortia. Other investigators have provided evidence supporting the possibility that biodegradation of refractory molecules may be stimulated through

application of a readily available carbon source to encourage development of a

decomposer population (Chou and Bohonos 1979; Clark, Chian, and Griffin 1979),

to facilitate cometabolism (Horvath 1972), or to encourage induction of appropriate enzyme systems (Atlas 1981, Chou and Bohonos 1979).

There are a number of ways in which microorganisms can interact with contaminants. These have been discussed by a number of authors, most recently by

Gunnison (1986). Perhaps the most familiar aspect of microorganismcontaminant interactions deals with direct transformation of chemicals through

biodegradation. Biodegradation can have a broad range of effects on the biological and chemical activities of xenobiotics. Alexander (1977) delineated

the various degradational processes and their consequences as follows:

a. Detoxication. Conversion of a molecule from a substance that is inhibitory in the concentration normally applied to the environment

into a product that is nontoxic.

b. Degradation. Transformation of a complex molecule into simple

products.

c. Conjugation, complex formation, or addition reactions. Processes

involving either an increase in the complexity of a substrate or a

combination of the substrate with microbial cellular metabolites.

d. Activation. Conversion of a nontoxic substrate or potential pesticide into a toxic substrate.

e. Alteration of the pattern (spectrum) of activity. Processes wherein

the metabolism of a pesticide or other biotoxic compound changes the

range of the compound from the species originally intended as the

target to another, dissimilar species.

227
The environment has a bearing on which of the above pathways are able to

function in the degradation of aromatic compounds. Environmental factors

involved in promoting, inhibiting, or preventing microbial degradation have

been considered by several investigators (Alexander 1977, Evans 19'7,

Matsumura and Bousch 1971, Woodcock 1971, Yoshida 1975). Some of these factors are particularly important in microbial metabolism in aquatic sediment,

including, for example, the presence of aerobic or anaerobic conditions, the

level of nutrients, pH levels, salinity, and temperature (Evans 1977). Some

authors have even discussed the possibility of altering the soil environment

to favor those microorganisms capable of degrading contaminants that are refractory in the present soil system (TNO 1984). It is possible that similar

processes can also be applied to the sediment environment to promote degradation of contaminants.

An additional environmental factor of critical importance in soil and

aquatic sediment is the nature and availability of sorptive surfaces. Sorptive capacity is of direct concern with regard to the mobility of chemical

contaminants, particularly any microbial processes that alter either the sorptive capacity of the sediment or the ability of the contaminant itself to be

sorbed. Sorptive capacity varies from one sediment to another, depending on

textural composition and organic matter content (Buckman and Brady 1969, Dale

1974, Marshall 1980) and on the grain size of the sediment (Dale 1974). The

nature and solubilities of contaminants already sorbed by the sediment are important determinants of mobility. Microbial modification of these substances

that results in a change in solubility can have both negative and positive aspects. Iron-oxidizing thiobacilli assist in the oxidation of iron pyrites,

possibly increasing the severity of an acid mine drainage problem. Alternatively, similar processes occur when metal sulfide ores are exposed during

mining activities. Here the formation of an acid mine drainage from these deposits can be an efficient means of extracting ore and may even be encouraged

by the mining company (Ehrlich 1981). In a similar vein, microbial modification 5f organic chemical contaminants in a sanitary landfill or a confined

disposal facility may be important, if the modification increases the solubility or lowers the sortive capacity of the soil or sediment. The concern here

is that the more mobile chemical species may be able to move out of the

landfill/disposal facility and into the ambient environment or down into the

ground water. Similar concerns have been expressed with respect to undesirable water quality impacts resulting from environmental alterations of the

sediment environment during resuspension and deposition of contaminant-laden

dredged material in dredging and disposal operations.

Extensive literature is available on biodegradation, but very little is

known of the effect biodegradation has on the mobility of contaminants or

their degradation products. Theoretically, some degradation intermediates behave very differently from the parent molecule. For example, high molecular

weight organic compounds are generally highly insoluble. If the molecular

weight of polymeric compounds is reduced by microbial activity, the solubility

and, consequently, the mobility may increase (Blum and Mills 1986). Other

kinds of degradation reactions may be important. The pctential for dehalogenation is important because the total number of halogens attached to an aromatic ring can greatly influence the environmental activity of the molecule.

The contribution of groups to activity can be expressed as a function of the

partition coefficient (Fujita and Nishizawa 1982). Each functional group is

assigned a PI value based on empirical determinations, and this can then be

228
used to compute a partition coefficient. The relationship may be an approximation, but it demonstrates that for many compounds, removal of halogens may

alter the partition coefficient; this, in turn, is related to the solubility

of the compound. With a decrease in the partition coefficient, the solubility

may increase to some extent, and the tendency for the compound to segregate

into organic complexes as a result of hydrophobic interactions decreases.

Most of the contaminants of public concern are not high molecular weight

compounds, and depolymerization of these compounds during degradation is not

likely to alter their mobility.

DOM is important in these reactions because dehalogenation is not coupled

to biosynthetic pathways in microorganisms. As a result, an energy source

other than the contaminant is required, at least for this part of the degradation. Higher concentrations of available DOM would result in higher levels of

indigenous microbial species, possible expediting the degradation process.

This process can be inhibited by a situation in which contaminants are complexed with DOM, shielding both the contaminant and the DOM from degradation.

Ring cleavage also has the potential to enhance the mobility of contaminants. The meta-cleavage pathway normally results in formation of dicarboxylic acids. As a result of the presence of easily dissociating protons on the

carboxyl groups, these compounds are often highly polar, readily solvated, and

very mobile in the environment. These compounds are quite different from the

original contaminant and may have important properties as described above.

Very little is known about the mobility of contaminant degradation products,

and future investigations may demonstrate the potential for breakdown intermediates of interest.

An additional area of direct interaction of microbes with contaminants

includes uptake, either actively or passively, and/or surface sorption of the

contaminant to the cell. These reactions include both organic and inorganic

substances. Once sorbed, the contaminant would move with the bacteria in suspension. If the ionic or chemical status of the environment changes, the contaminant could desorb from the bacteria. Alternatively, cell death could also

release the contaminant into the sediment or water.

Concentration of organic contaminants in sediment and water can influence

the manner in which these chemicals are metabolized and the rate at which they

disappear. For example, Wang, Subbarao, and Alexander (1984) have shown that

a chemical may be metabolized at one concentration and cometabolized at another. The presence of substrates in addition to the concentration of an organic contaminant is an important factor in determining the behavior of

contaminants in the environment. The rate of the cometabolism is highly dependent on the concentration of microbially available DOM in sediment and

water. One theory holds that heterotrophic bacteria require a minimum concentration of organic carbon to meet requirements for maintenance; below this

level, bacterial growth is unable to occur (Powell 1967). Microorganisms responsible for degradation of contaminants may be included in this group. As a

result, it is anticipated that levels of contaminants below the threshold

necessary to support microorganisms carrying out degradation will result in

very slow disappearance of the contaminant.

229
Sorption of Organics

Sorption reactions are important with respect to interactions between

contaminants and DOM for two reasons: (a) the contaminant may be directly

sorbed onto the surface of a particle, with the result that the contaminant

and the particle it is sorbed to may settle onto the sediment surface and become buried, and (b) DOM is often sorbed to organics and may contribute to the

sorption processes occurring in association with the particle. This role of

DOM in the reaction of contaminants and inorganic particles requires further

investigation.

Particulate and DOM Interactions

DOM can influence many aspects of the physical state and environmental

fate of organic contaminants. Humic substances, for example, can alter the

solubility of nonpolar compounds (Boehm and Quinn 1973; Hassett and Anderson

1979; Landrum et al. 1984; Mathur and Morely 1978; Matsuda and Schnitzer 1971;

Ogner and Schnitzer 1970; Wershaw, Burcar, and Goldberg 1969). Humic substances can also bind organic compounds by one of several different mechanisms, hydrolyze pesticides (Perdue 1983), photosensitize contaminants (Zepp,

Baughman, and Schlotzhauer 1981a, b), alter the bioavailability of contaminants to aquatic organisms (Leversee et al. 1983), and control the rate and

extent of biodegradation of organic compounds at low concentrations (Holm

et al. 1980, Schmidt and Alexander 1985).

DOM in general increases the aqueous solubility of hydrophobic organic

compounds, including pesticides (Marshall 1980; Wershaw, Burcar, and Goldberg

1969), n-alkanes, aromatic hydrocarbons, and dibutyl phthalate (Boehm and

Quinn 1973). and cholesterol and 2,2'.5,5'-tetrachlorobiphenyl (TCB) (Hassett

and Anderson 1979, 1982). DOM has been observed to influence hydrolysis of

organic contaminants (Li and Felbeck 1972a, b; Schmidt and Alexander 1985),

and a model has been formulated that includes the effect of DOM on hydrolysis

(Perdue 1983). Other studies have demonstrated that some chemicals photoreact

more rapidly in water when DOM is included (Mills et al. 1982; Powell 1967;

Ross and Crosby 1975; Zepp et al. 1975; Zepp, Baughman, and Schlotzhauer

1981a, b).

REACTIONS WITH METALS

Direct Reactions

Microorganisms exhibit a variety of activities toward many metals that

can have major influences on the mobility of these elements. Processes carried out by microorganisms may alter the Eh-pH of a system, and microorganisms

can also participate in a series of redox reactions that affect the mobility

of metals. For example, reduced metals are often more soluble and mobile than

their oxidized forms. Several metals are thought to function as redox species; however, with the exception of iron, there is little evidence to suggest

that the microorganism obtains energy from the oxidation process or by the

oxidized metal serving as the electron acceptor. Metals thought to undergo

microbial oxidation and reduction include As, Zn, Cu, Hg, U, and perhaps Cd

and Cr. In many cases, there is little clear information to indicate whether

there is a direct interaction between the metal and the microorganisms or if

the interaction occurs secondarily as a result of microbial modification of

230
the environment. For mercury there is good evidence for production of a mercury reductase system in several bacteria (Wood 1974); the product of mercury

reduction is elemental mercury, which is very mobile due to its volatility.

DOM would not be expected to influence oxidation of metals, providing

these reactions occur directly. It is expected that these oxidations are

carried out by autotrophs. However, reduction reactions can be strongly influenced by the quantity and quality of DOM; in this case, metals most likely

serve as terminal electron acceptors for heterotrophs. There is little information to indicate that metals other than iron and mercury undergo significant

direct oxidation or reduction. Some metals, including Hg, Sn, As, and Se, undergo methylation in anaerobic sediments with consequent formation of volatile

methyl complexes such as mono and dimethy mercury. These substances diffuse

rapidly through water and, under suitable conditions, into the atmosphere.

Such methylation/volatilization reactions are thought to be a part of a microbial strategy to convert toxic material into a form that moves away from the

area of the cell. Methylations occur under anaerobic conditions, and all microorganisms carrying out such reactions are heterotrophs.

Indirect Reactions

Metals generally sorb to particles or complex with organic matter through

a mechanism related to ion exchange, although many organometallic complexes are

bound together with covalent bonds.

Clays and other inorganic particles often have a net surface charge resulting from the arrangement of 0 and OH groups on the crystal surface as well

as from the internal composition of the crystal. The charge associated with

unshared oxygens or hydroxyl groups results from acid dissociations. At low

pH, the negative charge will be saturated with protons, and there will be no

charge to attract other cations. At higher pH, the supply of protons decreases and the resulting negative charge is fulfilled by other cations, e.g.,

metals. At pH ranges from 4 to 10, the pH of water in contact with sediment

particles may play a major role in releasing the metals from the surface of

the clay. Thus, in some low pH wetlands (acid bogs, for example) metals may

be more mobile as a result of the high proton concentration in the sediment

pore water and the water column displacing metals from clay surfaces. In

higher pH environments (marshes), cations such as metals are held more firmly

due to the lack of protons for displacement.

Davis (1982) has shown that a large percentage of the surface area on

most inorganic particles is coated with organics derived from dissolved material. The coating can interact in several ways, depending on pH, relative

surface area, amount of sorbable organic matter in the system, nature of the

solid substrate, and inorganic electrolytic composition. Dissolved organics

can act through various mechanisms to increase the sorption of cations through

increasing the effective number of negatively charged sites associated with a

particle.

Ionic reactions are largely responsible for sorption of metals to organic

particles. Carboxylic acids and phenols, the primary active sites on organic

particles (Schnitzer and Kahn 1972), are also important in interactions with

DOM. As was the case with clay, such reactions are pH dependent with the

specific effective pH range for effectiveness being dependent on the pKa of

231
the specific functional group. Because microorganisms mineralize organic matter in the sediment, they can play a critical role in determining the mobility

of metals bound to particles by organic compounds. In spite of this, there

has been no direct examination of this type turnover, nor any examination of

the fate of materials adsorbed to the particles.

There are several different types of reactions that may result in complexation of metals to dissolved compounds. Presence of carboxyl groups of

phenolic hydroxyls will create an ion-binding condition identical to that presented for organic and inorganic particles. Chelation is typical of this type

of reaction and is very important in movement of iron-oxide organic colloid

complexes in fresh waters as well as in liberating metals from surrounding

soils and in liberating metals from soils in the area and allowing movement of

metals into wetlands (Zyczynska-Bakoniak and Szpakowska 1985).

While many plants are able to remove metals from wetland sediments, the

major environmental concern is with the release of metals upon death and decomposition of the plant. This obvious area of research has never been addressed in a meaningful way. Many scientists consider particulate detritus as

an effective extractor of metals from water and an assistant in moving metals

to the sediment. The potential for metal release from decomposing saltmarsh

cordgrass was considered by Breteler et al. (1981), but their data showed an

enrichment in metal concentration in detritus over time. This suggested retention of plant-bound metals and perhaps sorption of metal from the water

column. Specific studies of metal exchange have not been performed; however,

present evidence suggests that net flux would be zero or into the organic matter (Giblin et al. 1983).

Changes in the Physical Environment

A potentially important contribution of DOM to the mobilization of contaminants in aquatic sediment and wetland soil is a consequence of the alterations in pH and Eh that occur in anoxic areas. Little is known about this

process. Much of the metal binding occurs on negatively charged sites associated with deprotonations associated with DOM and POM, and the pH of the

system greatly influences the number of sites available. Release of protons

by microorganisms during the decomposition of organic matter could decrease

the pH, if it were not for the fact that the protons released are usually accompanied by an anion to balance the charge. The question of how the decrease

in pH occurs is not always clear. In addition, in most sediments and flooded

soils, oxygen is absent and reduced products accumulate. The decrease of Eh

often has a marked influence on mobility of materials capable of undergoing

oxidation-reduction reactions, especially metals.

The literature does not present any information on the movements of most

contaminants between sediments and the water column when the sediment is reduced and oxidizing conditions are present in the water column. Several laboratory studies have examined the solubility of different redox species for a

variety of compounds. Integrated studies of the role of organic decomposition

on maintenance of low pH-Eh conditions in conjunction with mobilization processes are lacking. This represents a potentially important means of releasIng contaminants from sediments, and it is important to develop a better

understanding of this area.

232
CONCLUSIONS

The evaluation of existing literature on the role of microorganisms in

production of DOM and mobilization of contaminants makes it possible to say

something about the metabolism of contaminants in natural ecosystems, with

particular reference to aquatic sediment. A large variety of chemical compounds exists in sediment. These materials are of both natural and anthropogenic origin. Often, members of the native sediment microbial community are

able to multiply and utilize these substances. As indicated previously, a

microbial species having the enzymes necessary to degrade these materials may

not be present. However, there is always the possibility that microorganisms

having the capability may appear through one or more mechanisms; these include

invasion and genetic modification of native or invading species. Alexander

(1977) has noted that not all pollutants are organic, and a large number of

the organic contaminants are destroyed either principally or only by way of

microbial activities. Several organisms are capable of complete degradation,

partial conversion, or cometabolism of contaminants (Bourgquin and Pritchard

1979, Leisinger et al. 1981). Nonetheless, while some contaminants are easily

degraded, others are not and may be quite persistent. Metabolism of pesticides has been used by Alexander (1977) as an example of the ways in which

microorganisms act or fail to act upon pollutants.

Problems often arise as a result of the relationship of contaminants present in a sediment to the use or intended use of the aquatic ecosystem. Problems may arise with the intended use of other environments, if the latter are

potential locations for placement of a contaminated sediment. The problem becomes a concern from a legal standpoint when and if the accumulation of materials in the sediment is high enough to cause a conflict with legislative

mandates. For example, open-water disposal of contaminated dredged sediment

requires consideration of several legislative items, including the Fish and

Wildlife Coordination Act, the National Environmental Protection Act, the

Marine Protection Act, the Research and Sanctuaries Act, the Federal Water

Pollution Control Act, the National Ocean Pollution Planning Act, and the

London Dumping Convention. In contrast, freshwater concerns with aquatic sediment relate to many of the same, plus several additional pieces of legislation. The latter include the Clean Water Act, National Drinking Water

Standards, and state and local water quality criteria.

Interactions between microorganisms and DOM and contaminants have many

ramifications with respect to submerged sediments and wetlands. In addition

to the possible failure of microorganisms to degrade some contaminants or the

ability of other microorganisms to form undesirable products, consideration

must also be given to the possible changes that may occur if a sediment is

moved. Movement of a sediment from one location to another in an aquatic ecosystem may not necessarily cause a change in the sediment as a microbial habitat. However, placement of a sediment into another environment may result in

some severe changes, and these may then alter or influence the activity of the

sediment microflora. Finally, alteration of existing environments, such as

wetlands, may cause difficulties if contaminants are present of if the wetland

is important in removing contaminants from inflowing waters.

233
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238
TESTS ON SEDIMENT GAS GENERATION

T. Yoshida, K. Nikaido >

Jspan Bottom Sediments Management Association P

"- I

ABSTRACTT

In the past, many clean water projects have been s

implemented because of complaints from residents about

sediment odor. Thus, sediment odor is an important

environmental effect of sediment pollution. On the

other hand, research on its behavior has not advanced CD

satisfactorily. The second Port and Harbor Construc- -

tion Bureau of the Ministry of Transport is now studying the fundamental behaviors of sediment gases and

pollution control regarding sediment odor. For this

purpose, laboratory tests on sediment gas generation

were performed in 1984 and in 1985 by the Sediments

Management Association. This paper deals with those

test results.

SAMPLING SITES AND SEDIMENT PROPERTIES

Sediment samples were taken from the Shibaura Canal near Haneda Airport

in Tokyo Bay (Figure 1). The sediment there is highly polluted; therefore, it

was dredged in 1978 and 1980. The samples were taken from five points in 1984

and from three points in 1985.

TEST APPARATUS

The jar test column, made of acryl, had a diameter of 190 mm and three

columns with three height stages: 80, 130, and 180 mm (Figure 2). The sediment sample was placed at the bottom of the column to a height of 300 mm.

After the air above the sediment and water was removed by N2 gas, testing

began. Figure 3 indicates the relationship between ignition loss and COD concentrations. The samples were divided into two groups, high and low pollution. The water depth was 2.7 m and the sampled sediment depth was 15 cm.

Properties of the sediment samples (Figure 4) are listed in Table 1. The

heights of the overlying water were 40, 90, and 140 cm. The gas concentrations dissolved in the water in 1984 were as follows:

Concentration

Gas After 20 days

Methane (CH4 ) 0.578 mg/i

Hydrogen sulfide (H2 S) 26.6

Methyl mercaptan <0.0001

Methyl sulfide <0.0001

Methyl disulfide <0.0001

239 92-17640
River Arakawa

Tokyo Bay

4 A4

S\ > Haneda'

Figure 1. Sampling sites

From this, it was found that the generated gas was composed predominately of

CH 4 and H 2S. Therefore, gas analysis in 1985 was conducted only for CH4 and

H 2S.

OVERALL GAS TRANSFER COEFFICIENT

Gas transfer is depicted in Figure 5. The overall gas transfer coefficient KLa is defined by the following equation.

Vt KLa(Cg - Cw) (1)

m - gas concentrations dissolved in water, mg/1

V - volume of water

t - time

Ka = gas transfer coefficient

Cg - concentration of gas

Cw - concentration of water

The values of overall gas transfer coefficient for H 2S calculated from the

test results are shown in Table 2 and Figure 6. It is noted that the coefficient KLa depends upon the value of m (Figure 6).

240
- 3-way cock

Flow meter - 2-way cock

Gas

Siphon taken out

N2 gas -- - 3-way

cock /m-Ther 

eter

Activated

carbon

a Water

Air*

Sdiment

Water

taken 190 mm

out I

Figure 2. Test apparatus

mg/g

100-

1280-

8

0 0

0 60

U

4CIgnition Loss

Figure 3. Relationship between ignition loss

and COD

241

! q I I I I 20 = = ' ' 
S'2 S-N -S

S-7

Figure 4. Sampling points

TABLE 1. PROPERTIES OF THE SEDIMENT SAMPLES

Sampling Ignition loss COD Sulfide

Year Point % mg/g mg/g

1985 S-1 7.2 17.9 0.73

S-3 19.3 104 7.35

S-7 20.4 105 10.2

1984 S-1 20.5 79.4 5.71

S-2 21.0 95.9 8.04

S-3 23.0 101 7.91

s-4 22.1 94.8 7.30

S-5 11.0 8.8 0.21

TEMPERATURE EFFECTS UPON GAS GENERATION

Figure 7 shows the relationship between the dissolved gas concentrations

m and water temperatures for methane. This correlation can be represented by

the following equation:

mT = m20 1. 14 T-20 (2)

mT - dissolved gas concentrations at temperature T* C

m 20 dissolved gas concentrations at 200 C

For H2 S gas (Figure 8), the same equation can be obtained.

242
Air Chamber

Water Chamber

Concentration

Figure 5. Movement of gas CW g/ a

TABLE 2. KLa OF H2S

Sampling Height of Water

Point 140 cm 90 cm 40 cm Average

S-1 5.48 x 10-5 9.28 x 10-5 4.14 x 10-5 6.30 x 10-5

S-2 7.28 x 10-4 5.11 x 10-4 4.48 x 10-4 5.62 x 10-4

S-3 8.78 x 10-4 5.41 x 10-5 9.63 x 10-5 5.05 x 10-5

RELATIONSHIP BETWEEN DISSOLVED GAS CONCENTRATIONS

AND SEDIMENT POLLUTION

Figure 9 shows the relationships between sulfide concentrations in sediment and dissolved gas in overlying water. The figure clearly indicates the

strong relationship between sediment pollution and gas generation: the

greater the sulfide content in sediment, the larger the dissolved gas concentrations in the overlying water, and the higher the liquid height, the larger

the gas concentrations in the overlying water. Figure 10 shows the relationship between TOC and dissolved gas concentrations. From the figure it can be

seen that CH4 concentrations dissolved in the water increase rapidly if the

concentration of TOC exceeds 70 mg/g.

GAS GENERATION RATES

The gas generation rates (Figure 11) from sediment, represented by G

(mg/m 2 /day), can be obtained by the following equations:

243
GAt - m + G'At (3)

G 1- + G' (4) At

G - gas generation rates from sediment

A - cross-sectional area of the test column

t - time

m = dissolved gas concentrations in the overlying water

G' = gas generation rates at the water surface

1/d

6-

4

2

8

68

4?

S2-

10 20 Z5 0 10:0 M200- 4t400 600mg

Figure 6. Relationship between m and KLa

Since the values of m and G' are measured, the values of G can be calculated from Equation 4 (see Table 3). Figure 12 shows the relationships between sulfide concentrations in sediment and H2S generation rates. There is

clearly a linear correlation. There is also a strong correlation between TOC

and CH4 gas generation rates (Figure 13). In this case the correlation curve

is not linear and rapidly increases according to the increase of TOC.

GAS CONCENTRATIONS IN THE OVERLYING WATER

The dissolved gas quantities in the water are represented below as mentioned before:

Vt KLa(Cg _ Cw) (1, bis)

244
mg/A

5.0

0

4.0

Methane

3.0- t - 20 days

m

2.0- mT= m2 0 1. 14 T-20

1.0.0/ 0-

0 10 20 30 "c

Water Temp.

Figure 7. Temperature effects for CH4

This can be rewritten as follows:

y , HK~a(Cg - Cw)

The left term of the above equation is the dissolution rate of gas, which is

equal to the product of HKLa and the difference of gas and water concentrations. In Figure 14, taking a thin layer dz at the height of Z , we .can

consider the balance of inward- and outward-flowing gas material as:

Bc a2c Lc

at 3z2 KLH 8z

where

c - concentration in the water

K = diffusion coefficient of gas molecules in the vertical direction

z - height in liquid column

K La overall gas transfer coefficient

H - liquid height (total)

245
Mg A

mg/I I

80 H2 S

t = 10 days

60

m

40

20 o

10 20 30 °C

Water Temperature

Figure 8. Temperature effects for H2 S

The general solution of Equation 5 is represented as follows:

C - Aeat-bz (6)

By putting this into Equation 5

a - Kb2 _ KLaHb

we have then

C - Ae( a (7)

This equation represents the vertical distribution of water concentrations.

The boundary condition (Figure 15) at the sediment surface is as follows:

G (8)

246
o H- 140 cm

5 H2S

t- 20 days

400 / / H-90 cm

30C 0

0

200

100 0 H=i40 cm

o 0

0

0

0 2 4 6 8 10 mg%

Sulfide Concentration

Figure 9. Relationships between sulfide concentration in sediment and

the water

Then we get

G

A = G bK (9)

The boundary condition at the liquid surface is

-K- - G'

Therefore, we have finally

G' - Ge a (10)

From this equation, the value of K can be obtained. For example, from the

following data:

247
G - 699.1 mg/m 2 /day

C' - 0.0055 mg/m2/day (t - 10 days)

G' - 0.0085 mg/m 2 /day (t - 20 days)

we get

b - 8.7 1/m4

K - 7.16 x 10- m2 /day 8.29 x 10` cm2 /sec

mg/it

7OC

0

600

5C

40 0

m CH4 A

t- 20 days

300

200

0

100

0

0 20 40 60 80 mg/g

TOC

Figure 10. Relationship between TOC and m

248
Figure 11. Gas generation rates

TABLE 3. GAS GENERATION RATE VALUES*

Height of Water

Parameter 140 cm 90 cm 40 cm

G', mg/m 2 /day 0.0085 0.0296 0.0205

m, mg/m 2/day 555 342 82.6

m/At, mgfm2/day 699.1 670.1 364.2

G, mg/m 2/day 699.1 670.1 364.2

* S-7, t - 20 days.

Since the vertical distribution of water concentrations is now known, we can

calculate the value of m :

H G (b 2 K-bH) t-bz

m= j e \ dz a (11)

0

507 mg

There is a fairly good agreement between the calculated value of 507 mg and

the measured value of 555 mg (Table 3).

GAS EMISSION INTO THE AIR

This section will consider the odor problem at a sampling site. The

important matter is gas emission into the open air (Figure 16). As mentioned

before, gas generation rates in the overlying air are represented as follows:

G' - Ge ý 2 K-bHKLa)t-bH(10, bis)

249
mg/mr2 /day

700

4-)

E

0

L)

4.)

30

0

1a)

2 4 6 8 10 mg/g

Sulfide Concentration

Figure 12. Relationship between sediment sulfide

concentration and G

From this it is known that gas generation rates at the liquid surface are pro- -bH

portional to e . This means that the lower the water depth, the larger the gas emission into the air. For example, such a correlation is indicated

in Figure 17 regarding the S-3 sample. That is, if we compare the gas emission at water depths of 0.75 m and 1.4 m, the gas quantities at the former are

100 times larger than the one of the latter. Therefore, we must pay particular attention to odor emission at sites in shallow water.

The gas concentration at the water surface is represented as follows:

CA = Co1- Coe (b2K-bHKL)t-bH (12)

o 0G o

Then we have at the initial condition (t-o)

CA = C ebH (13)

250
mg/mr2 /day

500-

0.- H40 cm

CH4

400- t- 10 days

G 30C o

20C

100

"/ H= 140 cm

0 20 40 60 80 100 mg/g

TOC

Figure 13. Relationship between TOC and G for methane

az 3z

dz dm dmn= -H2- KL

Figure 14. Movement of gas in F F

the water Hz z

0

Sediment

251
Figure 15. Boundary conditions

m•

Co

Figure 16. Gas emission into the air

From this it is found that the larger the value of b , the lower the gas

concentration at the water surface. Therefore, in order to investigate odor

problems, it is necessary to know the value of b.

POLLUTION CONTROL WITH REGARD TOSEDIMEN ODOR

As mentioned before, the distribution coefficient b plays an important

role in gas emission into the air. If the relationship between the values of

b and sediment pollution is known, it is possible to obtain the gas concentrations in the overlying air resulting from sediment pollution.

Figure 18 shows the relationship between the values of b and sulfide

concentrations in sediment. The higher the sulfide concentration, the smaller

the value of b . Figure 19 shows the calculated gas concentrations CA at

M2CA

2527/01
lm m2 /day

Theoretical curve

00

144

0

010

Measured

00

S -3

b=6.4

0

g 10 G'(H=140 cm) = 1

0

A H2 S

U

10.4 07 0.8 09 1.4

m

Water depth

Figure 17. Gas emission according to water depth

the liquid surface with a parameter of b . Thus, the relationship between

sulfide and gas concentrations in the overlying air can be obtained as shown

in Figure 20. The toxicity of gases guideline is indicated in Table 4. If

the correlation curve is intersected by an appointed permissible concentration, the sediment removal limit can be obtained. For example, if the permissible concentration of H 2S is set at 0.2 ppm, the sediment removal limit becomes 6.5 mg/g of sulfide in sediment. That is, sediment having concentrations greater than 6.5 mgfg should be removed to prevent sediment odor.

CONCLUSIONS

These tests indicated that warm water temperature and shallow water depth

have adverse effects on odorous gas emission into the air. Therefore, a serious odor problem may occur in shallow rivers or canals and in suummer. Although the relationship between sediment pollution and odorous gas generation

has been obtained, this relationship is not enough for practical application

because in laboratory tests the effects of water flow are not taken into

account.

The concentration change equation. in an authentic canal or river is as

follows:

253
ac K 1a2C K tas ' ac_ U asac

at az 2 aH az

where U is the water flow velocity. Needless to say, it is necessary to

perform in situ tests to verify the effects of water flow.

12 11.3 o 10.6

•O S-3

U) o 8.7

8- 

S-7\

0U

-,40 6-

S~H- 140 cm. H4

w

2

I I I a

2 4 6 8 10 12 (mg/g)

Sulfide Concentration in Sediment

Figure 18. Relationship between sulfide concentration

and b

254
t 0

t - 100 days

0

.CY 10- * S10 *1) *1) Japan Industrial

* !Sanitary Association

4 •*2) Standard in the

( 3n Accommodated Area

S2 *3) Standard in the

c General Zone, Foul

0 1.- •Smell Protection Law

I 7:

00

C4

S2 2- *2)

0)

Q

u 7: K - 7.16x 10-4 m

w2 5- -4

cU 4 - K - 8.78x 10 l/

3-

2 *3)

0

5 6 .7 8 9 10 11 12

b

Figure 19. Calculated gas concentrations in the air

255
mg/k

S2.0-

L 44 1.8

S1.6

$4

tv 1.4

1.2

= 1.0

0 OB t= 100 days

4 04

0O- Permissible concentration

0

U 0.2" , - - Sediment removal 0 .,..0-o Ii -------- I

2 6 8 10 12 mg/g

Concentration of Sulfide

Figure 20. Relationship between sulfide concentrations

and CA

TABLE 4. TOXICITY OF H2 S

Concentration

ppm mg/f Effects to Human Body

0.02 0.00028 Standard in the general zone, Foul Smell

Protection Law

0.2 0.0028 Standard in the accommodated area

10 0.014 Japan Industrial Sanitary Association

70-100 0.1-0.15 Symptomatic after long hours

100-150 0.14-0.21 Symptomatic after several hours

170-260 0.24-0.36

360-500 0.4-0.7 Absorption during 0.5-1.0 hr is

dangerous

420-600 0.6-0.87 Sudden death after 0.5-1.0 hr

850-1000 1.2-2.8 Instantaneous death

1000-3000 1.4-4.2 Instantaneous death

256
DEALING WITH TOXIC POLLUTED SEDIMENTS IN THE GREAT LAKES BASIN

Peter L. Wise

Great Lakes National Program Office

US Environmental Protection Agency MW

230 S. Dearborn Street C

Chicago, Illinois 60604

w--

ABSTRACT

The United States and Canada signed the Great

Lakes Water Quality Agreement in 1972. In 1978, the ___

Agreement was expanded to cover pollution from toxic- C

chemicals. Since 1973 the Great Lakes Water Quality

Board has identified specific areas such as harbors, 00

river mouths, and connecting channels as geographic

areas of concern. Now the major problem in the majority of these areas is in-place polluted sediments.

The Water Quality Board instituted a new ranking system for these areas in 1985. The purpose of the new

system is to encourage progress and to allow the Board

to report the status of investigatory and remedial activities accurately. The United States and Canada

have banned production and use of certain toxic compounds such as DDT, dieldrin, and PCB's. The concentrations of these chemicals in fish have decreased

over the last several years. Now the concentrations

seem to be leveling off, probably due to the continuing reservoir in the sediments. The highest concentrations of PCB's, up to 520,000 ppm, are found in

Waukegan Harbor. The design of the proposed remedial

action, under the United States Superfund authority,

has been completed for Waukegan.

INTRODUCTION

This paper examines the binational approach of the United States and

Canada of dealing with the problem of in-place polluted sediments. It will

articulate the history of the designation of some 42 areas of concern (AOC's)

in the Great Lakes Basin (Figure 1) and outline the scheme that was developed

by the Great Lakes Water Quality Board to track progress and provide incentives to the states and the Province of Ontario to deal with their polluted

sediment problems. The paper will also discuss the environmental condition of

Lake Michigan as an example of the impact of in-place polluted sediment on the

Great Lakes Basin. As an example, the paper will review the in-place polluted

sediment problem found in Waukegan Harbor. Waukegan Harbor has the highest

sediment concentrations of polychlorinated biphenyls (PCB's) in the Basin

257 92-17641 UfhiII11DIIi 1111| DII~ 113 DI
i xi

* 0)

54.

ci

;t 00

0 r14

258
with concentrations of up to 520,000 ppm. The paper will outline the alternatives that have been considered and selected for remediation of the problem in

Waukegan Harbor.

In 1909 the Boundary Waters Treaty was signed by the United States and

Canada. Although concerned with water levels management, the Treaty provided

that neither party could pollute the waters of the other. The International

Joint Commission (IJC) was created by the Treaty to foster international cooperation in research, planning, and resource protection and to resolve disputes

arising under the Treaty.

Since 1973 the IJC's Great Lakes Water Quality Board has identified specific areas such as harbors, river mouths, and connecting channels which have

serious water pollution problems. In 1974, the Board identified 23 such areas

in the upper lakes and 46 in the lower lakes. From 1976 to 1977, the Board

continued to report on the problems of these AOC's. The 1978 Board report

suggested that these areas be classified into three categories: (1) water

quality objectives not achieved because remedial programs were not yet complete; (2) remedial programs completed but delayed before conditions in the

lake showed improvement; and (3) further remedial programs may be required.

A total of 48 problem areas were identified with these new criteria. Of

these areas, 26 were classified in Category 1, 6 in Category 2, and 16 in Category 3. In the intervening years between 1978 and 1985, the Water Quality

Board (WQB) struggled with varying ways to report on progress in the AOC's.

However, in preparing for the 1985 Board report, the Board was distressed because these areas had been AOC's for over a decade; yet, in almost every case,

little or no measurable progress had been made toward the restoration of beneficial uses.

In order to overcome these difficulties and to provide a more complete

and coordinated assessment of the data and information provided by the jurisdictions, the Board developed a new procedure for assessment of AOC's. In the

past, the Board had not always been clear on how to track and measure progress

in AOC's or how to remove the site from the AOC list. To alleviate these

problems, the Board adopted a new system of categories which represents a logical sequence for problem solving and resolution. The categories identify the

status of the information base, programs which are under way to fill an information gap, and status of remedial efforts. The heart of the concept is the

completion of remedial action plans. These plans are being developed to address specific problems causing use impairments. Resolution of the problems

takes place when evidence can be presented that the full complement of uses

has been restored and the site can be removed from the AOC list.

Specifically, the appropriate jurisdiction will now describe each of the

AOC's in relation to the following six-category sequence:

1. Causative factors are unknown and there is no investigative program

under way to identify causes.

2. Causative factors are unknown and an investigative program is under

way to identify cause.

259
3. Causative factors are known, but remedial action plan has not yet

been developed and remedial measures are not fully implemented.

4. Causative factors are known, remedial action plan has been developed,

but remedial measures are not implemented.

5. Causative factors are known, remedial plan has been developed, and

all remedial measures identified in the plan have been implemented.

6. Confirmation that uses have been restored and deletion as an AOC.

In Category 5, the effectiveness of remedial measures should be evaluated within a reasonable period of time, say 3 years, to determine whether or

not the measures were sufficient to restore beneficial uses in the AOC. If

not, it will be necessary for the responsible state or province to either determine additional remedial measures that will need to be implemented or indicate the level of environmental quality expected in the AOC should further

remedial actions be adopted.

This new scoring system of the AOC's serves two purposes. First, it allows the WQB to report on progress in AOC's. Secondly, and of equal importance, it provides an incentive for the states and the Province of Ontario to

move forward with the completion of remedial action plans and the implementation of programs to restore uses.

The WQB asked each of the states and the province to evaluate their AOC's

related to the six categories. The WQB asked these jurisdictions to then designate each of the AOC's, the category the area was currently in, and the

time frames required to complete the remedial action plans and submit them to

the WQB.

In order to continue to provide incentives to the states and the province, the WQB did two additional things. First, they developed a generic outline that articulates the components of remedial action plans, and, secondly,

they developed a review procedure by which the Board would review and comment

on the plans once they were submitted.

In all but four of the AOC's, surveillance and monitoring have found concentrations of one or more toxic substances which exceed guidelines or objectives for the protection of aquatic life, human health, or even open-water

disposal of dredged material. In some cases the reported levels only exceed

objectives and guidelines on a periodic rather than chronic basis; this suggests improving conditions. Fish advisories related to consumption for the

protection of human health are in effect in 31 of the 42 AOC's.

The most common source of continuing water quality problems in AOC's is

in-place pollutants, in many cases attributable to past waste discharges or

spills. According to EPA Great Lakes sediments guidelines, sediments in 38 of

the 42 AOC's are moderately to heavily contaminated, mainly with toxic substances. In some cases, the contaminated sediments have led to the destruction of local aquatic communities and are contributing to the high contaminant

levels observed in other environmental media. Where dredging for navigation

is required, it is often necessary to place restrictions on dredging-related

activities. Where such situations arise, special precautions with disposal

260
must be taken. In some cases, the sediments are so contaminated that they

must be treated as toxic or hazardous waste. In many of the AOC's, the sediments the Corps of Engineers dredges must be disposed of in confined disposal

facilities. The siting of confined disposal facilities has become more difficult due to increased public and Agency concerns over the suitability of these

facilities for sediments contaminated with toxics.

As EPA requires increasingly effective physical and biological isolation

of the pollutants in the sediments from the Great Lakes aquatic system, the

cost differential of confined disposal facilities vis-a-vis upland disposal

will continue to diminish.

The Corps of Engineers is undertaking a number of special studies with

EPA assistance to look at alternatives for disposing of heavily contaminated

sediments and to identify and quantify bioaccumulation and transfer of pollutants to the aquatic and terrestrial food chains. Two of these studies are

being undertaken in Indiana Harbor, an AOC, and in the Buffalo River area of

Buffalo, New York.

One of the significant shortfalls in the US environmental legislative

authority and funding support is direct assistance for the removal and treatment of in-place polluted sediments. Four of the 28 US AOC's are currently

designated on the national priority list for Superfund action; they are

Waukegan Harbor, Ashtabula River, Torch Lake, and Sheyboygan Harbor. In these

cases there are Superfund sites eligible for Federal cleanup, not because of

bioaccumulation into the food chain, which is the most significant problem

caused by in-place polluted sediments, but rather because there are existing

drinking water intakes located within a prescribed distance from polluted sediments. In addition, the Corps of Engineers undertakes routine navigational

maintenance dredging. However, this dredging oftentimes does not deal with

the vast quantities of contaminated sediments that lie outside the shipping

channel, or in areas that are not commercially navigable.

CONTAMINANTS IN THE BIOTA

Using Lake Michigan as an example, the concentrations of some toxic organic chemicals in Great Lakes fish have declined over the last decade. Despite this decline, fish advisories exist for all or parts of each of the

Great Lakes. These advisories warn against consumption of certain species and

recommend limiting the consumption of others. The chemicals that are currently driving both the banning of commercial fishing and the advisories related to sports fishing are primarily pesticides such as DDT and dieldrin and

industrial compounds such as PCB's. The reduction of these chemicals in Great

Lakes fish can be directly attributed to the fact that both the United States

and Canada have banned the production and use of these chemicals in the early

1970's. It is now hypothesized, however, that the concentrations of these

chemicals may be approaching a new equilibrium in the biota. This equilibrium

could be caused by the existence of continuing reservoirs of the chemicals in

the sediments as well as atmospheric sources. If it is true that we are at a

new equilibrium and that the fish concentrations will remain near existing

levels, the fishery will not return to an edible state unless sources such as

in-place polluted sediments are addressed.

261
The 1985 WQB report on Great Lakes water quality reported on trends of

contaminants in the biota by lake. Lake Michigan will be used as an example

here. There is now a consistent health advisory for all Lake Michigan fish

for all states. This health advisory on Lake Michigan fish is based on 1984

data and was released in March 1985. In general, fish contaminant monitoring

data for Lake Michigan show that levels of PCB's and banned pesticides contaminants are declining. The 1984 data show that the contaminants in coho

salmon, rainbow trout, and lake trout less than 51 cm in length have decreased

to the point where 90 percent or more of the fish tested do not exceed US Food

and Drug Administration (FDA) Action Levels. However, contaminant levels in

over 90 percent of the lake trout, carp, and brown trout remain high. It is

recommended that no one eat these fish (Table 1).

Examining fish concentration data for bloater chubs, lake trout, and coho

salmon, the US Fish and Wildlife Service and EPA have documented substantial

declines in both DDT and PCB's from 1969 to 1982. Dieldrin has apparently not

responded as rapidly to remedial actions, as evidenced by its apparent increase since 1969. In general, dieldrin concentrations in lake trout increased between 1970 and 1979 followed by a decrease between 1979 and 1982

(Figure 2). Coho salmon data confirm this trend between 1980 and 1984. It is

now believed the dieldrin problem is related to deep depositional areas.

The Canadian Government has demonstrated that concentrations of DDE, DDT,

HCB, MIREX, and total PCB in herring gull eggs have decreased dramatically in

the last decade (Figure 3). As is the case with Lake Michigan fish, dieldrin

concentrations in herring gull eggs from Lake Michigan remain relatively high

and have not decreased rapidly as a result of remedial measures.

The majority of the fish addressed in Lake Michigan health advisories are

species that are not typically residents of a particular harbor or river

mouth. Salmon and trout tend to migrate freely throughout the entire basin.

Therefore, little detailed evidence can be submitted that would indicate that

the polluted sediments in these harbors are causing the continuance of levels

of these chemicals in Great Lakes fish. Carp, however, remain on the advisory

because they continue to have high levels. It is worth note that carp from

areas of contaminated sediments have higher levels, for example, 90 to 100 ppm

PCB's in Sheyboygan Harbor.

EPA, in conjunction with the states, is beginning a series of evaluations

on localized species, such as spottail shiners. In addition, specific bioaccumulation tests are being conducted in a number of the AOC's to determine the

bioavailability of the chemicals to the biota.

WAUKEGAN HARBOR REMEDIAL ACTION

The EPA has attempted to use as many of its authorities and resources as

possible in addressing AOC's. Because of the administrative limitations on

Superfund, the hazardous waste cleanup authority has been brought to bear in

only four of the AOC's. Waukegan Harbor, perhaps the most notorious AOC in

the Great Lakes, is one of the most highly PCB-contaminated sites in the

United States. The figures are overwhelming; over 300,000 lb of PCB's are

contaminating slip 3 in the upper harbor of Waukegan Harbor and over

750,000 lb of PCB's are contaminating portions of the soils of the nearby Outboard Marine Corporation property. Sample results from the harbor sediments

262
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Figure 2. Mean annual dieldrin, total DDT, and PCB concentrations (mg/kg wet weight; with 95% confidence intervals) in whole fish samples of

lake trout collected from eastern Lake Michigan. (Data from US Fish and Wildlife Service. From 1972-76 PCB was quantified using

1:1:1 Aroclor 1248, 1254, and 1260; beginning

in 1977, only Aroclor 1254)

264
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Figure 3. Mean organochlorine contaminant concentrations (mg/kg wet weight

± S.D.) in herring gull eggs from Lake Michigan's Big Sister

Island, 1971-1983. (Data from Canadian Wildlife Service)

have shown PCB levels and concentrations up to 520,000 ppm (52 percent). EPA

has estimated that between 30 and 40 lb of PCB's are released to Lake Michigan

by water movement annually, while some 12 to 40 lb are released into the atmosphere. There is a ground-water plume migrating toward Lake Michigan that in

the future will contribute another 8 lb/year to Lake Michigan proper. The

City of Waukegan has an emergency water intake in Waukegan Harbor, and while

it has been used only six times since 1978, this intake is the basis for Superfund involvement. EPA fish studies in Waukegan Harbor indicate that levels

of PCB's exceed the FDA Action Level of 2 ppm. Samples taken range from 2.7

to 187 ppm.

There is little dispute that this contamination resulted from years of

discharge into Waukegan Harbor by the Outboard Marine Corporation (OMC).

Between 1952 and 1971, OMC purchased approximately 9 million pounds of PCB for

use in its die casting machinery and other equipment. The major portion of

the PCB's was used as a cooling fluid in the die cast operation. It is estimated that at least 10 to 15 percent of this material leaked through floor

drains into Waukegan Harbor and the North Ditch drainage system.

265
EPA has attacked this Waukegan Harbor problem from two perspectives, legal and technical. On the legal front, EPA and OMC differed greatly on

whether the concentrations of PCB's present a danger and what to do about

them. OMC repeatedly asserted that PCB's in and around Waukegan Harbor present no danger. Indeed, OMC is fond of asserting that EPA "admitted" as much

when it responded in the course of litigation that it knew of no specific persons affected by PCB contamination from Waukegan Harbor. Fortunately, with

the passage of the Clean Water Act, Congress provided EPA the authority to act

on chemical exposure via the water route before the fact of demonstrated human

injury. EPA must act to protect the public health. PCB's are not natural to

the Great Lakes ecosystem. Therefore, evidence of toxicity in animals is sufficient for EPA to take action. The truth is less ingenuous.

Years of Agency experience with PCB's have demonstrated the chronic dangers which PCB's present. PCB's are known to have carcinogenic effects on rodents and to cause chloroacne and reproductive disorders in humans. They are

also suspected of other disorders in both humans and animals.

In 1978, the Agency used the only options available to it by commencing

judicial action against OMC. Many frustrating years of litigation followed.

When the Superfund statute passed, the Agency believed it had a means for accomplishing its goal of a cleanup, which years in court had not achieved.

Subsequent to the engineering design for the removal and disposal of the PCB's

from Waukegan Harbor, OMC engaged in litigation against EPA, this time over

property access issues. The remedial activity, which will be described later,

is still in its design phase.

Early in the design process, the Agency requested access to OMC's property for the limited purpose of doing survey work and taking soil borings.

OMC refused. Although EPA did not prevail in court on the access issue, now

with pending Superfund reauthorization, it appears that this stumbling block

will be removed. OMC and EPA have recently met to once again begin negotiations for the express purpose of reaching agreement on how and what should be

done in terms of removal.

In 1984, EPA signed a decision document authorizing the expenditure of

$21 million for the design and cleanup of the entire Waukegan site. Although

many alternatives were examined for the cleanup, the recommended alternative

consists of: (1) dredging of the upper harbor down to 50 ppm; (2) dredging

and deep excavation of slip 3; (3) construction of a bypass sewer line through

the north ditch; (4) construction of a slurry wall around and a clay cap over

both the oval lagoon and the crescent ditch after hot spot (over 10,000 ppm)

removal; (5) containment of parking lot contamination by slurry wall; (6) construction of an aboveground containment cell on the parking lot area to hold

contaminated materials removed from the upper harbor in slip 3; and (7) fixation and offsite disposal of materials excavated from slip 3, the Crescent

Ditch, and the oval lagoon (hot spots). (This material would be disposed of

offsite in certified hazardous waste landfills.) The design work began in

December 1984 but was put on hold in March 1985 due to the ongoing litigation.

There are two remaining issues related to this example of a Great Lakes

polluted harbor that need to be mentioned. The new Superfund reauthorization

now pending in Congress makes a strong statement about the ultimate destruction of toxic materials rather than the removal and disposal of toxic

266
materials. There is a belief that the removal of the toxic material from

Superfund sites and the transport by rail or road to disposal facilities increase the risk of human exposure and set up the situation where the disposal

facility ultimately will have to be dealt with sometime in the future. If

Waukegan Harbor is not resolved quickly, it may come under the auspices of the

new Superfund legislation. It is likely that the destruction of the dewatered

sediment by an incineration-type method will be carefully considered and perhaps recommended. If this technology is, in fact, chosen, the cost--which in

1984 was $21 million--will undoubtedly double and likely triple. The second

remaining issue relates to the level of cleanup. EPA has estimated that if

sediments are removed down to a 50-ppm level, that would virtually eliminate

movement between the harbor and the lake. Certainly the vast majority of the

exposure would have been removed. It is likely, however, that once the

cleanup is completed, tests will have to be run as to the bioavailability of

the remaining PCB's in the harbor, and additional steps by either the restriction of movement of the biota or additional cleanup may be required.

CONCLUSIONS

In conclusion, the sediments contaminated with toxic materials in the

Great Lakes Basin remain one of the most significant issues in the basin. The

WQB has recognized this and has attempted, by establishing a new process of

ranking AOC's, to provide the incentive to the Great Lakes States and the

Province of Ontario for action. Although scientifically not a certainty, it

is projected that until Canada and the United States address in-place sediment

problems in harbors and river mouths, it is reasonable to believe that consumption advisories on sport fish and limits on commercial fishing will remain. This would certainly be true in some localized areas.

EPA and the Corps of Engineers have limited authority to deal with this

problem. To date our Superfund program has been able to deal with only 4 of

the 28 US AOC's and, as demonstrated by Waukegan Harbor, this is a timeconsuming and costly process.

Both the US House of Representatives and the Senate have reauthorized the

Clean Water Act. This bill recognizes the need to address in-place polluted

sediments. They have authorized EPA to undertake a 5-year demonstration program for the removal, treatment, and disposal of in-place sediments in Great

Lakes AOC's. If funds are appropriated for this activity, EPA will work with

the US Army Corps of Engineers to continue to develop technical approaches for

dealing with in-place polluted sediments. Ultimately, however, either the

Federal Government or the States will have to bear the burden of the costs of

the removal and destruction of polluted sediments.

267
-* EVALUATION OF CHEMICAL POLLUTANTS BY ANALYSIS OF OIL

COMPONENTS IN SEDIMENTS

K. Ninomiya a) Yokohama Environmental Research Institute

Takigashira, Isogo-ku, Yokohama 235, Japan

TABSTRACT

•-• Partitioning of oil and chemical substances in

- the bottom sediments off the coast of Yokohama was investigated to study the behavior of chemical substances in the environment. Concentrations of

lipophilic substances were proportional to concentrations of oil in the sediments. From these results we

could characterize the sediment contamination of the

area.

INTRODUCTION

As a direct consequence of the PCB environmental pollution issue, the

"Law Concerning the Examination and Regulation of Manufacture, etc., of

Chemical Substances" was enacted in October 1973 in Japan. As a part of the

Chemical Assessment Project, the Environment Agency of Japan systematically

examines the safety of chemical substances in the environment, and estimates

contamination levels in the environment (Environment Agency 1982).

Lipophilic substances such as PCBs and chlordanes, which are nearly insoluble in water, tend to be accumulated in the fat of fish (Japanese Society

of Public Health 1984). Therefore, both the concentrations of organochlorine

compounds and the content of fat can be determined simultaneously in analyses

of fish (Environment Agency 1982). Previous laboratory experiments revealed

that about 90 percent of hexachlorobiphenyl in water was extracted into suspended oil and sediment after efficient mixing (Sayler and Colwell 1976) and

that both particle-size distribution and total organic carbon in bottom sediments are important factors in determining the extent of PCB partitioning

(Steen, Paris, and Baughman 1978). Similarly, lipophilic substances in the

environment should mix with oil since oil has analogous physicochemical

properties.

This paper will report on an investigation of the relationship between

concentrations of oil and chemical substances in the bottom sediments off the

coast of Yokohama (Figure 1), the western part of Tokyo Bay (Ninomiya et al.

1984).

92-17642

268
KAWASAKI

!" \

~T RUMI RIVER \

YOKOHAMA

KTABIRA RIVER e

%---•-"/ OKA RIVE

TOKYO,• o,••• •oo,

269
SEDIMENT CONTAMINATION IN YOKOHAMA WATERS

Concentration of Oil

in the Bottom Sediments

Coast of Yokohama

After sediment samples were collected at eight sites along the coast of

Yokohama (Figure 1) and dried at room temperature, oil was extracted using

carbon tetrachloride. The concentrations of oil are shown in Figure 2.

Site No.

1

2

3

Figure 2. Concentration of oil 4

in sediments off the 5

coast of Yokohama 6

7

8

0 1000 2000

Concentration of oil (plg/g dry)

The total concentration of oil was higher in the northern coast (sites

1-4) because of effluents from the factories located in Keihin Industrial

Area, established in the 1930's. The concentration of oil was highest at

site 4 (Yokohama Port), in which the current is stagnant and the discharge

from many ships and tankers is difficult to disperse (Ninomiya 1982).

Tsurumi River

Tsurumi River, which runs through northern Yokohama, is about 42 km in

length and flows into Tokyo Bay. Sediment samples were collected at 20 sites

along Tsurumi River. The sites were located within 29 km of the mouth of the

river (Figure 3). In this experiment, ethyl acetate was used as extractant.

The concentrations of oil are shown in Figure 4.

The concentration of oil was higher at the sites located between the

mouth of the river and about 6 km upstream. The maximum concentration was

measured at site 5, about 4 km from the mouth of the river (Ninomiya 1983).

Nonpolar Oil as a

Characterization of Oily Pollutants

By fractionating the oily extract of the sediment from Tsurumi River using chromatography on silica gel, oil was separated into two components, nonpolar and polar. The percentage of the nonpolar component in the total oil is

shown in Figure 5.

Oily e t The first fraction eluted by n-hexane.

extractpTr oil)

--[The second fraction eluted by ethyl acetate.

(polar oil)

270
TSURUMI RIVER

BAY

Figure 3. Sampling sites along Tsurumi River

6000

S4000

` 2000-

0 i

0 10 20 30

Distance from the mouth

of Tsurumi River (km)

Figure 4. Concentration of oil

in sediments in Tsurumi River

The higher percentage of polar oil at the middle and upstream sites is

suspected to be caused by the inflow of domestic effluents and the benthic organisms, while the percentage of nonpolar oil at the downstream sites might

come from the effluents containing petroleum from industrial and urban areas.

The extraordinarily high percentage of nonpolar oil, as high as 85 percent, at

site 8 should be explained by the local pollution o' the river due to

petroleum-containing effluent (Ninomiya 1983).

OUTLINE OF ENV(RONMENIAL SURVEY OF CHEMICAL SUBSTANCES

We have investigated the levels of contamination by chemical substances

in water and bottom sediments since 1976 in cooperation jith the program

271
-80

0

S60- '~O

0

0

Figure 5. Percentage of nonpolar 40 " 40,

oil in total oil sedi- 0

ments in Tsurumi River I

02 0 1 03

S0 0 10 io ýo

Distance from the mouth

of Tsurumi River (km)

planned by the Environment Agency. Samples were collected at three sites each

in the mouth of Tsurumi River (T) and in Yokohama Port (Y) of Tokyo Bay, as

shown in Figure 6.

The drainage basin of Tsurumi River in Yokohama is about 143 kn2, with a

population of 800,000. Katabira River and Ohoka River, which run into the bay

of Yokohama Port, drain a total area of 151 km2 . Approximately 1,060,000 people live in the drainage basin of these two rivers.

From 1976 to 1985, field surveys were conducted on 161 substances, and 44

of the 161 substances were detected. Reflecting the tendency of accumulation

in the bottom sediments, a larger number of substances was detected in bottom

sediment than in water, as shown in Table 1.

TSURUMI RIVER \-AWASAKI

U.•

YOKOHAMA

Figure 6. Sampling sites in the RITVER T-2 T-3

mouth of Tsurumi River

and Yokohama Port

Y-2 Y-3

YOKOHAMA

TOKYO BAY S~N

OHOKA RIVER

0 2km

272
TABLE 1. SUBSTANCES DETECTED, DETECTION RANGE, AND DETECTION RATE IN

YOKOHAMA, 1976-1985

Year Substance Sample Detection Range* Detection Rate

1976 Aniline Water 0.00011-0.0011 20/20

Aniline Sediment 0.0016-0.50 20/20

m-Chloroaniline Water 0.00021-0.00034 5/20

m-Chloroaniline Sediment 0.0005-0.019 13/20

p-Chloroaniline Sediment 0.001-0.27 17/20

o-Chloroaniline Sediment 0.001-0.008 9/20

3,4-Dichloroaniline Water 0.00032-0.00042 3/20

3,4-Dichloroaniline Sediment 0.0077-0.49 14/20

2,4-Dichloroaniline Sediment 0.005-0.0058 2/20

N-Ethylaniline Sediment 0.0083-0.037 6/20

p-Toluidine Sediment 0.0038-0.046 9/20

o-Toluidine Sediment 0.011-0.046 8/20

m-Toluidine Sediment 0.0023-0.038 12/20

p-Anisidine Sediment 0.0017-0.0055 4/20

o-Anisidine Sediment 0.0083-0.057 6/20

2,3-Xylidine Sediment 0.028-0.09 4/20

3,5-Xylidine Sediment 0.0022 1/20

PCN Sediment 0.34-0.67 3/3

PCT Sediment 0.65 1/3

2-Naphthylamine Sediment 0.027 1/20

1977 Tributhyl phosphate Water 0.00003-0.00005 6/6

Tributhyl phosphate Sediment 0.0026-0.0074 6/6

Nitrobenzene Water 0.0007-0.001 2/6

1978 PCT Sediment 0.14-0.30 3/6

HCB Sediment 0.0016-0.0041 4/4

Polyoxyethylene- Sediment 8.6-29 6/6

alkylphenylether

1979 1,2,4-Trichlorobenzene Sediment 0.0092-0.03 5/6

Ethylenediaminetetra- Sediment 2.3-13 5/6

acetic acid

Organosilicone compounds Sediment 4.2-12.2 5/6

Chlorinated paraffins Sediment 1.7-7.4 6/6

1980 Organosilicone compounds Sediment 6-22 6/6

Chlorinated paraffins Sediment 1.4-8.5 6/6

N-Phenyl-l-naphthylamine Sediment 0.03-0.04 5/6

N-Phenyl-2-naphthylamine Sediment 0.02-0.03 3/6

1981 N-Phenyl-2-naphthylamine Sediment 0.006-0.016 4/6

Hexachlorophene Sediment 0.005-0.098 6/6

(Continued)

* Units: Pg/ml for water, vg/g dry basis for sediment.

273
TABLE 1. (Concluded)

Year Substance Sample Detection Range* Detection Rate

1982 trans-Chlordane Sediment 0.0008-0.0064 5/6

cis-Chlordane Sediment 0.0005-0.004 5/6

trans-Nonachlor Sediment 0.0005-0.007 5/6

cis-Nonachlor Sediment 0.001-0.0031 4/6

Heptachlor Sediment 0.0012 1/6

y-Chlordene Sediment 0.0003-0.001 2/6

Hexachlorophene Sediment 0.009-0.17 6/6

Di-n-butyl phthalate Water 0.00006-0.0001 4/6

Di-n-butyl phthalate Sediment 0.068 1/6

Di-n-heptyl phthalate Sediment 0.071-0.24 5/6

Di(2-ethylhexyl)phthalate Sediment 0.069-3.5 6/6

Polyoxyethylene-type Sediment 0.16-2.0 6/6

nonionic surfactants

Polyoxyethylene Sediment 0.27-1.0 5/6

alkylether

Polyoxyethylene Sediment 3.5-4.9 4/6

alkylphenylether

1983 Alkyldimethylbenzyl- Sediment 0.9-5.2 6/6

ammonium chloride 6/6

Fluorene Sediment 0.03-0.09 5/6

Diphenylmethane Sediment 0.02-0.16

1984 Acenaphthylene Sediment 0.67 1/6

1985 1,3,Dimethyl naphthalene Sediment 0.062 1/6

274
PARTITIONING OF OIL AND CHEMICAL SUBSTANCES

Thirteen substances were detected in bottom sediments in 1982 (Table 1).

The detection rate (number of detected samples/total numbe- f samples) was

more than 5/6 for eight substances as shown in Table 1. Itiey were transchlordane, cis-chlordane, trans-nonachlor, di(2-ethylhexyl)phthalate, din-heptyl phthalate, polyoxyethylene-type nonionic surfactants, polyoxyethylene

alkylether, and hexachlorophene (Table 2).

This study was aimed at examining concentrations of chemical substances

in the environment. Concentrations of the substances in the bottom sediments

are presented in Table 3 (Ninomiya et al. 1984).

Check on Local

Contamination of Oily Discharge

Generally, oil is composed primarily of fatty matter (polar oil) from

animal and vegetable sources and of hydrocarbons (nonpolar oil) of petroleum

origin. Nonpolar oil percentage increases as local contamination by oil discharge of petroleum origin increases. The percentage of nonpolar oil at all

sites was compared as shown in Table 4. The average percentage of nonpolar

oil was 59 percent for the samples from the mouth of Tsurumi River and

70 percent for the samples from Yokohama Port. The percentage for the port

was higher than the percentage for the river.

Figure 7 shows the concentration of polar and nonpolar oil as a function

of the concentration of total oil for Yokohama Port and Tsurumi River. The

total oil versus polar oil plot can be approximated by a single straight line,

while the total oil versus nonpolar oil plot consists of two lines of similar

slopes but unequal intercepts corresponding to the two areas. The set of

three points in Yokohama Port consists of a straight line that is parallel to

but higher than the line from the set of three points in the mouth of Tsurumi

River. The long-term accumulation of mineral oil from the ship discharges is

believed to be the cause of a remarkably high percentage of nonpolar oil in

the sediment of Yokohama Port. Accordingly, there was no sample that was locally contaminated by oily discharge in either area.

Relationship Between

Oil and Chemical Subtances

To examine the contamination of the two areas of Tokyo Bay, the concentrations of the chemical substances were plotted against the concentration of

total oil (Figure 8). As shown in Figure 8, the total oil versus chemical

substances plots consist of two lines of similar slopes but unequal intercepts

corresponding to the two areas, except for polyoxyethylene alkylether and

hexachlorophene.

Lipophilic chemical substances such as chlordanes dissolve into oil on

their way of running off in drainage basin, because the chemical substances

and oil are analogous in physicochemical properties (Taylor and Colwell 1976).

And the oil containing the chemicals has accumulated in sediment at mouth of

river and off coast. Therefore, the concentration of chemical substance in

bottom sediments should be proportional to that of oil. Although there are

only a few samples, the total oil versus chemical substances plots can be

275
TABLE 2. WATER SOLUBILITY, USE, AND AMOUNT OF PRODUCTION OR IMPORT

OF THE EIGHT SUBSTANCES DETECTED IN 1982

trans-Chlordane Water solubility 9.45 x 10-2 Ug/ml

C Use for termites, wood and

•cl C plywood

CI H Amount of import 1,320 tons as chlordanes

C1 C1 H

C1

cis-Chlordane Water solubility 6.60 x 10-2 ug/ml

Use for termites, wood and

CI .. CI plywood

C HCI, CH Amount of import 1,320 tons as chlordanes

C1 C1 H C1in 1981

H

trans-Nonachlor Water solubility 5.66 x 10-2 Pg/ml

C C Use for termites, wood and

C• H plywood

C1 iH Amount of import 1,320 tons as chlcrdanes

H in 1981

CI 1 H

Hexachlorophene Water solubility : Sparingly soluble

OH OH Use : In past as bathroom agent

c1 c C1 and industrial antiseptic, now as disinfectant

Amount of import : A ton in 1981

Di(2-ethylhexyl)phthalate Water solubility : 6-18 ug/ml

Use : Plasticizing agent for

Cý'h vinyl chloride products COOC-CH-(CHjCH. Amount of production : 223,243 tons in 1981

aCOOCH,-C ,H-(C H,}kCH,

CA-,

Di-n-heptyl phthalate Water solubility : 20 jig/ml

OO(CH,).CH, Use : Plasticizing agents for

[WCO0(CH'CH, leather, hose, and paste

OO(CkH)CH, Amount of production : 36,175 tons in 1981

Polyoxyethylene-type nonionic Water solubility : Well soluble

surfactants Use : Detergents and permeative agents, etc.

Amount of production : 146,233 tons in 1981

Polyoxyethylene alkylether Water solubility : Well soluble

Use : Detergents, etc.

RO(C,HO)•H Amount of production : 146,233 tons as

polyoxyethylene-type

surfactants in 1981

276
TABLE 3. BOTTOM SEDIMENT DATA FROM THE MOUTH OF TSURUMI RIVER AND

YOKOHAMA PORT, 1982 (ug/g DRY BASIS)

Site Water Content Ignition Loss Total Oil Nonpolar Oil Polar Oil

T-1 43 5 414 198 147

T-2 69 14 3880 1790 1150

T-3 66 16 823 388 261

Y-1 81 13 5650 3700 1530

Y-2 73 16 5530 3310 1520

Y-3 73 12 4270 2710 1100

trans- cis- transSite Total Carbon Total Nitrogen Chlordane Chlordane Nonachlor

T-1 0.58 0.058 0.0002 0.0002 0.0002

T-2 4.0 0.44 0.012 0.0067 0.0070

T-3 1.4 0.12 0.0008 0.0005 0.0005

Y-1 4.5 0.41 0.0064 0.0040 0.0054

Y-2 4.6 0.34 0.0060 0.0038 0.0061

Y-3 3.4 0.27 0.0022 0.0013 0.0010

Polyoxyethylene PolyoxyDi(2-ethylhexyl) Di-n-heptyl nonionic ethylene

Site phthalate phthalate surfactants alkylether Hexachlorophene

T-1 0.069 0.012 0.16 0.2 0.009

T-2 3.5 0.23 1.7 1.0 0.050

T-3 0.36 0.071 0.54 0.5 0.016

Y-1 2.5 0.084 1.5 0.27 0.17

Y-2 3.2 0.24 2.0 0.35 0.16

Y-3 0.88 0.11 0.99 0.41 0.068

277
TABLE 4. PERCENTAGE OF NONPOLAR OIL IN TOTAL OIL

Site

T-1 T-2 T-3 Y-1 Y-2 Y-3

Percentage 57 61 60 71 69 71

--- nonpolar 4000

polar

,0

0 the port

Figure 7. Plot of concentra- = 002000

tions of nonpolar the river "

and polar oil versus concentration

of total oil

0 2000 4000 6000

Total oil (pg/g dry)

approximated by two straight lines for each area as shown by the following

formula:

Y = A(X - B)

where

Y = concentration of chemical substance

A = slope of line

X = concentration of oil

B = x-axis intercept of line

With respect to the substances except polyoxyethylene alkylether and

hexachlorophene, A for the mouth of Tsurumi River was nearly equal to A

for Yokohama Port. However, B for the mouth of the river was much closer to

the origin of the plot than B for the port. Chemical substances such as

chlordanes in sediment are mostly derived from urban runoff (Fukushima 1986).

On the other hand, oily pollutants come from two different sources; urban

runoff and ship discharge. Oil from ships accumulates in sediment off coast,

soon after it discharges. Therefore, it contains far less amounts of chemical

substances than oil from urban runoff. As a considerable portion of oil in

the port comes from ship discharge, B for the port should be greater value

than B for the mouth of the river.

278
-trans-

- chlordane di(2-ethylhe--

xyl)phthalat' cis- , 00 chlordane d heptyl,/

0.010 trans- /phthala e

a. nonachlor,

Sthe port //W

Cthe /iezrzz

S0.005 -. 0

cul

0 U 0 / O0 00 40 p 00 •---

0 2000 400'0 6060 0 2000 4000 6000

Total oil (pg/g dry) Total oil (pg/g dry)

a. Chlordanes b. Phthalic acid esters

polyoxyethylene-type

2" nonionic surfactants * 000.2

__ polyoxyethylene 00

Salkylether ,o /1 *

130J

(0 C

00.1

M °a

0-,0

A °

0 2000 4000 6000 0 2000 4000 6000 Total oil (.g/g dry) Total oil (pg/g dry)

c. Surfactants d. Hexachlorophene

Figure 8. Plot of concentrations of chemical substances versus

concentration of total oil

For the chemicals, B represents the concentration of oil not related to

the chemicals, and A is equal to the average proportion of the chemicals in

the oil containing the chemicals. Nearly equal A values for the two areas

of the bay implies that the concentrations of the chemicals in the contaminated oil are similar in the two areas. This leads to the conclusion that the

contamination by the chemicals and the oil containing the chemicals proceeds

similarly in the two areas of the bay.

Evaluation of Sediment Contamination

Table 5 indicates the slope A and the intercept B in the two areas of

the bay.

279
TABLE 5. SLOPE A AND X-AXIS INTERCEPT B

trans- cis- transArea Chlordane Chlordane Nonachlor Hexachlorophene

A* T 3.5 x i0- 6 2.0 x 10-6 2.1 x I0-6 12 x I0-6

Y 3.0 x 10-6 2.0 x 10- 6 3.6 x 10- 6 73 x 10-6

B** T 500 500 500 0

Y 3,500 3,600 4,000 3,300

Polyoxyethylene

Di(2-ethylhexyl) Di-n-heptyl nonionic Polyoxyethylene

Area phthalate phthalate surfactants alkylether

A* T 1,000 x 10-6 60 x 10-6 420 x 10-6 250 x 10-6

Y 1,500 x 10- 6 70 x 10-6 550 x 10-6 -100 x 10-6

B** T 400 100 0 0

Y 3,700 3,000 2,800

* Unit: Vg/ug.

** Unit: ug/g.

As expected, A values for all the lines are positive except polyoxyethylene alkylether, which shows a slightly negative A . The negative A

may arise from the fact that surfactants are more soluble in water and decompose faster via the microorganisms than the other substances. The hexachlorophene A value for Yokohama Port was about six times as large as A for the

mouth of Tsurumi River, probably because the hexachlorophene load in the port

is considerably larger than in the mouth of the river. Of the other substances, A values for Yokohama Port are slightly larger than A for the

mouth of the river.

The values of A for the chemicals decreased in the following order:

di(2-ethylhexyl)-phthalate, polyoxyethylene-type nonionic surfactants,

polyoxyethylene alkylether, di-n-heptyl phthalate, hexachlorophene, and chlordanes. The values of A for the chemicals were compared with the amount of

their productions or imports in Japan (Table 2) since A values for the chemicals should be correlated with the amount of the chemicals consumed in the

drainage basin and since the amount of their consumptions is said to be proportional to the amount of productions or imports. In accord with this hypothesis, A values increase in the increasing order of the productions or

imports of the chemicals except for hexachlorophene; this hypothesis was supported experimentally.

280
The values of B for chlordanes in the mouth of Tsurumi River are nearly

500 ug/g, but those in Yokohama Port are 3,500-4,000 pg/g. The values of B

for di(2-ethylhexyl)phthalate is nearly equal to B for chlordanes. The

values of B for the other chemicals in both areas are lower than B for

chlordanes and di(2-ethylhexyl)phthalate.

The data show a definite empirical relationship between oil and chemical

substances. The relationship is that the concentrations of chemicals in

bottom sediments are proportional to the concentration of oil. If the relationship is confirmed through additional future efforts, it would be expected

to provide a method for qualitative estimation of contamination by chemical

substances: there are comlpications and difficulties in determining the concentrations of chemical substances in bottom sediment. We can consider a

simplified method to estimate the concentrations of chemical substances, when

we want to know the distribution of chemical substances. First, we derive a

regression formula from the field survey at several sites in an area. Second,

we can estimate the concentrations of chemicals from the concentration of oil

at the other sites in the same area.

SUMMARY

This investigation studied the relationship between the concentrations of

oil and the chemical pollutants in bottom sediments off the coast of Yokohama.

The data show a possible relationship, although the amount of data are only

three data points per contaminant per harbor. Additional data from other

sampling locations in these and other harbor would be needed to develop an

accurate predictive methodology to estimate the concentrations of chemicals

from the concentration of oil.

ACKNOWLEDGMENTS

Many laboratories of the local governments and the other members of our

laboratory are thanked for the analyses of the chemical substances.

I express sincere appreciation to Prof. Minoru Hirota of Yokohama

National University, and Mr. Haruo Tsuruta of Yokohama Environmental Research

Institute for the helpful review of the manuscript. And thanks are due to

Mr. Thomas R. Patin of USAE Waterways Experiment Station for providing useful

comments.

REFERENCES

Environment Agency/Office of Health Studies, Department of Environmental

Health. 1982. "Chemicals in the Environment," Report Series No. 8.

Japanese Society of Public Health. 1984. "Study of Bioaccumulation Test in

Fish and Shellfish for Chemical Substance," Environment Agency report.

Ninomiya, K. 1982. "Pollution Index of Sediment - Eh, Oil and Differential

Thermal Analysis," Annual Report of Yokohaira Environmental Research Institute,

No. 7, pp 81-88.

281
Ninomiya, K. 1983. "Sediment Pollution Caused by Oil in Tsurumi River,"

Annual Report of Yokohama Environmental Research Institute, No. 8, pp 119-126.

Ninomiya, K., Shirayanagi, Y., Ohba, E., Fukushima, H., and Koichi, Y. 1984.

"Relation Between Oil and Chemicals in Sediment at Coast of Yokohama," Annual

Report of Yokohama Environmental Research Institute, No. 9, pp 151-160.

Sayler, G. S., and Colwell, R. R. 1976. "Partitioning of Mercury and Polychlorinated Biphenyl by Oil, Water and Suspended Sediment," Environmental

Science and Technology, Vol 10, pp 1142-1145.

Steen, W. C., Paris, D. F., and Baughman, G. L. 1978. "Partitioning of

Selected Polychlorinated Biphenyls to Natural Sediments," Water Research,

Vol 12, pp 655-657.

Fukushima, M., Kawai, S., Chikami, S., Morioka, T. 1986. "Urban Runoff as a

Source of Selected Chemicals to River Waters," Annual Report of Osaka City

Institute of Public Health and Environmental Sciences, No. 49, pp 11-20.

282
GAS GENERATION IN CANALS OF TOKYO PORT

Y. Matsumoto, Y. Ishli, K. Shimura

Department of Construction, Bureau of PortSand Harbors

Tokyo Metropolitan Government (BPH TMG) 8-1

Marunouchi 3-chome, Chiyoda-ku, Tokyo 100, Japan

-- -

ABSTRACT0 --0)

Gas generation in canals of the Tokyo port has

been studied to identify its mechanism. The major C

component of generated gas is hydrogen sulfide. Gas

emissions from sediment into water are closely related

to the depth of water and tide. Emissions per half

days were 4 to 11 t/m 2 for the 1-m depth of water or

less and 1 i/m 2 for water more than 2 m depth. Emission of gas into water began during the ebb tide,

indicated maximum value about 1 hr before low tide,

reduced during the flood tide, and became almost zero

after high tide. According to seasonal variations of

generated gas, emissions are greatest in August, being

over 100 times more than those in October. Gas emissions are suppressed significantly by sediment dredging; gas emissions measured after dredging were

reduced to 1/300 to 1/200 of those measured before

dredging. The concentration of hydrogen sulfide was

attenuated by water at a rate of 1/3 per meter. Generally, the relationship between sediment thickness

and gas emissions was not clearly determined.

INTRODUCTION

The importance of water areas in maintaining the good condition of the

environment of a city has been pointed out lately--primarily because the water

areas are attractive as landscape and can be utilized as an element for recreation, and thus makes up part of the living environment.

The canals of the Tokyo Port have been used not only to transport cargo

but also as living areas for Metropolitan citizens and for recreation. The

grounds alongside the canals have been redeveloped, changed from sites for

warehouses to areas for residences including apartment houses and parks.

But the canal area has problems with contamination of water and sediment

and offensive odors. To solve these problems, the Tokyo Metropolitan Office

has been engaged in dredging the canal since 1972. This dredging project will

have removed 3 million cubic metres of sediment by the end of 1986, costing 10

billion yen.

92-17643 28 llll~lJ~llilll
Along with this project, the Tokyo Metropolitan Government has performed

various surveys, including quantitative examination of effects of sediment

removal and investigation of its standard. This paper, following "Analytical

Survey of Accumulations of Sediments in Canals of Tokyo Port" presented by

Kimura, Naganuma, and Wano in the 11th Conference, identifies the mechanism of

sediment contamination and gas generation.

Gas generation is studied by using gas samplers installed in the canal to

determine (1) the relationship between tide and gas generation, (2) seasonal

changes of gas generation and effects of dredging, (3) attenuation of hydrogen

sulfide in water, and (4) relationship among gas emissions, water depth, and

sediment thickness. The status quo of the organic pollution of sediment that

significantly affects gas generation, and actual environments of the canal

including seasonal changes of water contamination are presented in Shimura

(1985).

STUDY SITES AND METHOD OF STUDY

Study Sites

The study sites are shown in Figure 1 as oblique lines in canals of the

interior of Tokyo Bay. These canals are located in Kohtoh, Shibaura, and

Keihin Districts. The canals of the Shibaura District are considerably polluted in terms of water quality and sediment (Shimura 1985). In order to

determine some of the characteristics of gas generation, the present study was

carried out in the Shibaura District where the worst sediment contamination is

found. Figure 2 shows the stations of study.

Method of Study

A funnel-like gas sampler (Figure 3) was used to collect generated gas.

Five hours before low tide, a set of gas samplers was fixed on a post, and the

collector bottles filled with seawater up to the zero mark. Water levels in

the bottle were recorded every 30 min from 4 hr before the beginning of low

tide to 1 hr after the end of low tide. At the same time the range from the

collector bottle to the water surface, and the water depth were measured.

Gas volume data taken every 30 min were corrected with respect to water

pressure. Gas was also collected on upper, intermediate, and bottom layers in

order to investigate attenuation of the components of generated gas in water.

Gas generation was surveyed in the ebb tide periods during the spring tide in

summer (August) because this month corresponds to the worst pollution period

of water and sediment. Gas generation was also surveyed in March, October,

and December to examine seasonal variations.

RESULTS AND DISCUSSION

Gas Generation

Gas Emission Volume

Figure 4 shows the maximum gas emissions and variations in the concentration of hydrogen sulfide in stations. This figure shows that more gas is

emitted and the concentration of hydrogen sulfide is higher at statiors in the

284
_ _Study area and

Figure 1. General map of Tokyo Port

interior of the Shibaura District (S-4, S-5, S-6, S-7, S-8, S-13) and at stations belonging to tne vest Shibaura canal (S-1, S-2, S-3). This coincides

with the report of sites worse in water and sediment contamination identified

by Shimura (1985). This water area, adjacent to the Shibaura sewage disposal

plant, contains more organic matters due to sewage discharges.

285
"• i5SIbMojio Bridge

Bridge

CU% Yatiyo

Takahama Bridge Bridge S Dredging area in 1975

- ,o*' -Dredging area in 1977

SShiauran. 7(anal C -g Bridge 1 Furukawa rkw

Canaoh Water

h Bridge Shioji Bridge Gate

SShibaura Canal Urashiua Bridge

Figure 2. Typical area of sediment contamination (Shibaura District).

Stations measured: S-1-S-14

Vinyl pipe

Hook

H- See level

A: 20CM

( Weight )

A: Gas Collector

B: Glass Bottle for Gas Measurement (H2 S,CH3 SH)

C: Installation of Sampler

Figure 3. Gas sampler

Offensive Odor Gas Components

This study analyzed two components: hydrogen sulfide and methyl mercaptan. Figure 4 indicates that the stations where the concentrations of hydrogen sulfide are >6,000 mg/f correspond to S-2, S-3, S-4, S-5, S-6, S-7, S-8,

and S-13 belonging to the interior area and the west Shibaura canal water

area. At these stations, more gas is generated. For methyl mercaptan, few

values available for analysis were detected.

286
nS 1Ltl0L

S-3 S-4 S-5 S-6 S-10

S-2

S-14i

n1.40 1.480

2L.31 0 .o n.470 5-9 S-12

II 1.17 453 1.12 15

Figure 4. Maximum value of the gas emission and concentration

of hydrogen sulfide (H2 S). Open bar: maximum value

of generated gas volume (j/m 2 /hr); hatched bar:

H 2S concentration (ppm)

Tide and Gas Generation

The maximum tidal range in the Tokyo Port is 2.10 m. As gas generation

may be affected significantly by variations in water pressure, the relationships among water depth, tidal changes, and gas emissions have been

investigated.

287
Gas Emissions and Water Depth

Figure 5 shows the relationship between gas emissions and water depth.

At four stations, S-2, S-3, S-8, and S-13, where the water depth is below I m

during low tide, generated gas volumes ranged from 4.1 to 10.9 £/m2 /half day.

At the stations where the water depth is above 2 m during low tide, generated

gas volume is 1.0 £/m2 /half day. Thus, gas emissions are significantly affected by water depth during low tide. Stations S-I and S-7, however, show

high generated gas values of 4.0 to 7.0 I/m 2 /half day, although the water

depth during the low tide was about 2.5 m. This would result because gas

emissions at these stations were affected by water depth, as well as geographical conditions and accumulated contaminated sediment.

Gas Emissions and Tidal Changes

Figure 5 shows the relationship between gas emissions and temporal tide

changes. Gas emission is highest from an hour before low tide to low tide

except for S-13, where a high gas emission began 3 hr before low tide and the

maximum emission occurred an hour before low tide. Thus, for the relationship

between tide and gas emissions:

a. Gas emissions vary depending on tidal change.

b. While the gas emission pattern is different quantitatively depending

on the accumulated contaminated sediment and geographical condition,

gas emissions begin during the ebb tide, peak about 1 hr before low

tide, are reduced during flood tide, and close after high tide.

The above facts lead to an understanding that anerobic generated gas accumulated in sediment is suppressed by water pressure during high tide and is

not discharged into water, and gas is emitted during low tide when the water

pressure is reduced. Hence, it is obvious that water depth is closely related

to gas emission.

Seasonal Variations of Gas Emissions

and Dredging Effects on Gas.Emissions

At five stations, S-1, S-3, S-4, S-6, and S-10, seasonal variation on gas

emissions and dredging effects on gas emission were investigated. Figure 6

shows the maximum gas emissions and seasonal variations in the concentration

of hydrogen sulfide at these stations, and during years when dredging was

performed. For seasonal variations of gas emissions and effects of dredging

on gas emissions, the following facts have been identified:

a. Seasonal variations in gas emissions.

(1) Gas emissions at station S-1 reach a maximum value in August and

are reduced from October and subsequently become nearly zero.

They then begin to increase again in March. Through 1 year, gas

emissions during August are at a maximum and are over 100 times

more than the emissions from October on.

288
S-1 (24/8/79) S-2(24/8/79)

5.0 Cumulative .10 s.0 10 Gas Volmwe .0 Cumulative

4.0 8 Gas Volume -8

S3,0 8 3.04 6

Sea Level

Z2.O 4 ".2.0 Sea Level 4

1.0 2 1.0 2

7 8 9 1011121314151617 7 8 9 10111213014151617

Time (h) Time (h)

S-3(23/8/79) S-4(24/8/79) S

-• 10 • 5.0 10 0 Q4

4.0 Cumulative Gas Volume . 4.0 8

"e..Cumulative Gas Volme

3.0 C3.0 4

•- 2 ,0 Sea Levelv

SLSeaLevel

1.0 2 1.0 2

C5

7 8 9 101112131415161718 7 8 9101112131415161718

Time (h) Time (h)

S-5(24/8/79) S-6 (24/8/79)

-10 C

40O 4.0-S

*o U

Cumulative Gas Volume

.S 3.0 - ~ nltv Ga VIm 3.0- Cumulative -6 :p

Sea Level V. Volume Gas Voo je

1.0 -2 1.0 2

7 a 9101112131415161718 7 8 9 101112131415 161718

Time (h) Time (h)

Figure 5. Time series of gas emission volume and

sea level (Continued)

289
S-7 (24/8/79) S-8 (24/8/79)

4.0 4.0- 8., -

3.0 Sea Level 6 3.0- Cumulative 6

Gas Volume

"7Z 2.0 Cumulative 4 "20- 4

Gas Volume

1O 22 1.0 Level 2

78 91011121314 15 16 1718 7 8 9 1011 12 13 14 15 161718

Time (h) Tim (h)

S-9 (24/8/79) S-10(24/8/79)

5.0 -10&0 o 0 O

4.0 8 84.o

- 4.

to 9j -p r- SeaLevel

0ea Level 4 2.0 4

to Cumulative 2 1.0 ..... e2

Gas Volume ~~~U cumulative . . . , ,. .i..a•- Ga~s Volume

7 8 910111213141516117 7 8 91011121314151617

Time (h) Time (h)

S-11 (24/8/79) S-12 (24/8/79)

5.0 - 10 "•5.0 10 "0

4.0 * &ý Sea Level

2 4 - •3.o0 .=3.0 >

C..

1.0 12 • 10 2 2

Cumulative Gas Volume Cumulative Gas Volume

7 8 91011121314151617 7 8 91011121314151617

Time (h) Time (h)

S-13 (24/8/79) 12

5.0 -Cnumulative 10

Gas Volume

4.0-e

3.0 6 U

~2D4

1.0 Sea Level

7 8 9 10 11 12 13 1415 1617

Time (h)

Figure 5. (Concluded)

290
ftm viii. o0 Gas

Enihsion I/ df/tr, l V*S CMWen"trtIOn( W.

LIN

urn

LLSii UI

&ia N Dec IMr. An MW Der 4r.

S-3

fIm-- v4ii. of Gs

Emission ( it/ .1/hr) P-S Doeece tia0t m)

!• 1.171

1.51 -

11.; 3.111

._4 1.3 L4.3 r n Ai 1r. i Na x M. "1. Me .. #, Ir 

S-6

-- S-10

CI ae ~~ n 99us ~ Dee~j P ~svaisr (f A O~

p a . usoval of 6rs

2.71 EnassamE ission_____________)

32• S42 4 23 rv area in Am W tee or.

As~~~~* .Dc my. r Dec Nor. 

Figure 6. Seasonal variation of gas emission. Open bar:

value by forced ejection

(2) Several hydrogen sulfides were sampled by forced ejection in the

study after October; therefore, the concentration of hydrogen

sulfide was not measured under the same standard through all

periods of the study. But it may be reduced from October on.

Thus, August has the worst conditions for seasonal variations of

291
gas emissions and gas components because the sediment temperature is higher, thereby causing higher activity of anerobic

bacteria.

b. Effects of dredging. The effects of suppressing gas emissions by

dredging have been estimated by comparing the gas emissions and concentration of hydrogen sulfide at a station without dredging (S-1)

with dredging stations (S-3 and S-6). At station S-i, the concentration of hydrogen sulfide in March is only somewhat lower than that in

August. At S-6, however, no gas is sampled in spite of an attempt at

forced ejection. The concentration of hydrogen sulfide at S-3 after

dredging is 34.5 ppm, only 1/300 to 1/200 of the value before dredging. This signifies that gas emission is considerably suppressed by

dredging.

Attenuation of Hydrogen Sulfide in Water

Anerobic gas generated and accumulated in the sediment is emitted into

water as the sea level decreases. Part of the anerobic gas is dissolved into

water while the rest is emitted into the air. Emitted gas can be sampled at

several depths, and the concentrations of hydrogen sulfide contained in the

sample gas measured at these depths can be used to examine attenuation of

hydrogen sulfide in water. Table I shows the relationship between the water

depth and the residual rate of concentration of hydrogen sulfide at the depth

of sampling (residual rate: concentration of hydrogen sulfide at sampling

depth/concentration of hydrogen sulfide on sediment). Figure 7 shows these

relationships.

The residual rate of the concentration of hydrogen sulfide (including

some deviated values) indicates nearly a linear relation for the passing

depth.- The regression equation is:

y - -0.3234x + 1.0132

where

y = residual rate

x = passing depth

Thus, it has become obvious that the concentration of hydrogen sulfide is attenuated in water by about 1/3 per meter. Hence the maintenance of sufficient

water depth will significantly reduce the amount of hydrogen sulfide gas emitted to the air.

Relationships Among Depth of Water,

Sediment Thickness, and Gas Emissions

As presented earlier, water depth has a negative correlation with gas

emissions. As the sediment is related to gas generation and accumulation, the

thickness of sediment will be positively correlated to the gas emissions. To

identify the relationship of water depth and sediment thickness to gas emissions, new stations are arranged transversely near station S-3 (Figure 8).

Figure 9 shows the maximum value of generated gas (I/m 2 /hr), cumulative gas

volume (per half days), water depth, and sediment thickness.

292
TABLE 1. RESIDUAL RATE OF H 2S IN WATER

Passing Depth Residual Rate

Station Sampling Time of H2 S, m of 2S

S-3 Before dredging 0.30 0.868

S-3 0.10 1.009

S-3* 0.70 0.079

s-6 1.05 0.450

S-6 1.05 0.840

S-11* 2.30 1.000

S-li 1.90 0.919

S-i Oct. 1979 2.81 0.093

S-1 2.73 0.228

S-I 2.56 0.205

S-3 0.83 0.950

S-6 2.36 0.203

S-6 1.84 0.119

S-6 1.70 0.950

S-10* 2.97 0.506

S-i Dec. 1979 2.40 0.192

S-6 Dec. 1979 1.30 0.560

S-10 Dec. 1979 1.50 0.246

S-4" After dredging 1.36 0.030

S-4 After dredging 1.38 0.637

* Shows the -lected data.

293
0 Y- -0.3234x + 1.0132

-C5 •

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Passing Depth (W)

Figure 7. Relationship between the residual rate of

H 2S in the water and the passing depth

/ Shinshiba Canal S-4

0

Shibaura Bridge

(Shibauranishi 

CanalN

B:Sane Station,S-3

2-6m E D C B A

E3

Direct to Takahama

Water gate

Figure 8. Distribution of new stations to

analyze the relationship among

water depth, gas emission, and

sediment thickness (near

Shibaura Bridge)

294
S-3-A (1) Thickness S-3-8 (2) Thickness

of Sediment 0.50. of Sediment 0.70.

4.0- .8 4.0-

6 S3.0 M" 130. Cumulative Gas Volue. 6

Cumulative

2.0. Gas Volume 4 2.0 4

'e Io~ Level LS Sea Level. M

C4,

7 8 9 101112131415 7 3 9101112131415

Time (h) Time (h)

S-3-C (3) Thickness S-3-D (4) Thickness

Sof Sediment 0.60m of Sediment 1.50m

4.0. 40_ 8

Cumulative Gas Volume > Cimulative Gas Volume

Cuuaie a oumaie §

3).0 20.

4,20 4 wa~le 2_ .0- 4 --

Sea Level Sea Leve I *

1.0 -2 w o

71 9 101112131415 7 6 9 101112131415

Time (h) Time (h)

S-3-E, Thickness of S-3-E 2 Thickness of

Sediment 0.75m Sediment 1.00m

Cumulative 8

4,0-Gas Volume 4.C a

.3um0lative

7 3 9 101112131415 7391

Time (h) Tm h

S-3-re2 9 Thickes of iso a msso e ee

2957

Sedmen 0.6 el Se

4t0 C 2qwto Se Lvev71 012345789111111 6 

Seiet..0

42.0 --

11 

-ve I7689 101112131415

Time (h)

Figure 9. Time series of gas emission and sea level

295
Gas emissions at the new stations showed the same pattern as the old stations, peaking about an hour before low tide. The maximum gas emissions

(9/m 2 /hr) are shown under multiple regression analysis by using the water

depth and sediment thickness. Figure 10 shows the results. The maximum gas

emission is negatively correlated with the water depth except at station A.

It is difficult to find any relationship between sediment thickness and the

maximur *as emission due to considerable deviations.

a

C C

D.0- D2.0-D

2 E2

A A

1.0- * 1.0-

, II _ _ _ _ _ I _

1.0 2.0 1.0 2.0

Depth of Water (m) Thickness of Sediment (m)

Figure 10. Relationship between gas emission volume and water

depth or sediment thickness (stations as shown in

Figure 9)

Table 2 shows the results of the multiple regression analysis. Except

for station A, the multiple regression coefficient is not less than 0.9, showing a high correlation. Two partial regression coefficients indicate that the

maximum gas emission has a negative correlation with water depth and a positive correlation with sediment thickness. It can be seen that water depth

affects gas emission more significantly than sediment thickness.

TABLE 2. MULTIPLE REGRESSION ANALYSIS

Multiple Correlation

Coefficient Regression Equation

Data Except X1 :Depth of X 2:Thickness of

All Data for A Water Sediment

Maximum Gas 0.295 0.999 Y = 3.39 - 1.63 X + 0.30 X2

Emission (Y)

z96
CONCLUSIONS

The results of this study can be summarized as follows:

a. Gas emissions in canals are 4 to 11 I/m 2 /half day for the stations

where water depth is below 1 m, and 1 I/m 2 /half day for the stations

where the water depth is above 2 m; gas emission is therefore closely

related to water depth.

b. Gas emissions in the canal area are affected considerably by tidal

variations. The variations bqgin during the ebb tide and peak about

an hour before the lowest tide. Gas emissions are then reduced during flood tide and nearly cease after high tide.

c. Through I year, the maximum gas emission occurs in August, being over

100 times more than the emissions produced from October on.

d. After dredging, the concentration of hydrogen sulfide is reduced

to 1/300 to 1/200 of that observed before dredging, indicating that

the effect of dredging is significant.

e. Hydrogen sulfide concentrations are attenuated by water at a rate of

about 1/3 per meter.

f. Gas emission are correlated negatively with water depth and positively with sediment thickness. Water depth affects gas emissions

considerably. On the other hand the relationship between gas emissions and sediment thickness is not clearly determined.

FUTURE PROBLEMS

The mechanism of gas emission in canals of Tokyo Port has been almost

understood through this study.

Canals have been dredged by the Tokyo Metropolitan Office to prevent

offensive gas. It has become obvious that this dredging does suppress gas

emission.

The water quality in Tokyo Port has been improved significantly compared

with that in the last half of 1960's through reinforcement of drainage restrictions and extension of sewage systems. In recent year, however, the

water quality has stopped improving; there are some problems including frequent generation of red tides due to eutrophication in Tokyo Bay. To solve

these problems it is necessary that new ideas and operations for prevention of

water and sediment contamination will be carried out in the near future.

The Bureau of Harbor Service now V as a plan for investigating the resedimentation mechanism after dredging. Including this study, the new operation of sediment removal will be fulfilled soon. Details of these projects

will be reported separately.

297
REFERENCES

Kimura, S., Naganuma, T., and Wano, S. 1985. "Analytical Survey of Accumulations of Sed'merts in Canals of Tokyo Port," Management of Bottom Sediments

Containing Toxic Substances, Proceedings of 11th U.S./Japan Experts Meeting,

Water Resources Support Center, Fort Belvoir, Va.

Shimura, K. 1985. "Aquatic Environment of Tokyo-Port, Water Quality and Bottom Sediment Quality of Tokyo-Ports' Canals," Proceedings of the 13th Symposium on Environmental Problems.

298
-• DEVELOPMENT OF THE PORT OF LONG BEACH:

PAST, PRESENT, AND FUTURE PROJECTS

G C. F. Connors, E. C. Kelly

G Port of Long Beach

925 Harbor Plaza

Long Beach, California 90802

<-

ABSTRACT

The development and expansion of the Long Beach

and Los Angeles Harbors in San Pedro Bay has been an

ongoing effort involving dredging and associated landfill, construction of breakwaters and bulkheads, and

other measures related to the conservation, development, and management of water and related land resources in the harbor area.

The southwestern and midwestern sections of the

United States are in a period of extensive growth,

creating a need for an expanded port; increased use of

containerization in shipping also requires more land

in order to guarantee an efficient operation. Through

extensive studies of historical, current, and projected use of the Ports of Long Beach and Los Angeles,

it has been determined that San Pedro Bay will need an

additional 2,600 acres of land to help handle the anticipated 223,210,000 short tons of cargo passing

through the Ports by year 2020.

This paper describes the development of the Long

Beach and Los Angeles Harbors from the late 1800's,

when the area was a large expanse of mudflats and

shallow water, to the present: the largest harbor

complex along the west coast of the United States. A

discussion of future developments is also presented.

Particular attention will be given to the subjects of

dredging and landfill and their important role in the

development of the Port of Long Beach, and to the high

regard given to mitigation trade-offs.

INTRODUCTION

Over the past 75 years, the Port of Long Beach has grown to be one of the

busiest ports on the west coast of the United States. This achievement is the

result of hard work and dedication of many people as well as some fortunate

natural circumstances.

92-17644

299 1llf |111 \
Geolegic conditions, including natural land topography, sediment properties, and subsidence, have provided a physical setting conducive to port

development.

Since the late 1800's, when the harbor was a muddy slough, land and water

have been rearranged continuously. The Federal Government initiated the first

improvement of San Pedro Bay in 1871 by constructing a 6,700-ft jetty connecting the west end of Rattlesnake Island with Deadman's Island, which provided

better protection for ships and deepened the entrance channel from 2 ft to

10 ft at low tide (Smongesky 1983).

Dredging and landfill are still reshaping the harbor; however, over the

years, this process has come to demand serious consideration. Each design

plan must be studied not only for construction detail, but also for its effect

on the environment.

These plans, their implementation, and the resulting mitigation projects

are discussed in this paper.

EARLY HISTORY OF THE PORT OF LONG BEACH

The Port of Long Beach is located in San Pedro Bay, a half-moon body of

water with a natural protection on the west by bluffs; however, on the southwest, south, and southeast, harbor protection is by man-made breakwater. The

San Gabriel and Los Angeles Rivers emptied into the original tidal lagoon, and

in 1825 a great flood increased this drainage basin from 700 square miles to

approximately 1,700 square miles.

Great quantities of silt and debris were brought down the rivers over

several centuries. The action of winds, waves, and ocean currents formed a

narrow sand spit approximately 4 miles in length known as Rattlesnake Island

(Figure 1).

North and west of Rattlesnake Island was a large expanse of mudflats and

shallow water about 2 ft deep at low tide. The construction of a jetty connecting the westerly end of Rattlesnake Island with Deadman's Island provided

better protection for ships and deepened the entrance channel by 8 ft.

From 1907 to 1909 much work was performed on the harbor. The San Gabriel

River was deepened and straightened for I mile, the turning basin and certain

navigable channels were dredged, and the barrier beach separating the ocean

from the San Gabriel River channel was dredged out at high tide creating the

ocean entrance to Long Beach Inner Harbor (Smongesky 1983).

This entrance channel was to be protected by rock jetties projecting into

the Pacific Ocean on either side of the channel, each approximately 1.6 miles

long with a middle breakwater 3.5 miles long.

Figure 2 shows development of the Port from 1905 through 1960. Figure 3

represents the Port of Long Beach as it exists today.

300
IL

IN

U)

All''

hitl

oI z

IL a'

.... ..,I.....4.

3011
OIIAL SITEINEHABRD4SN 0:W&L \OPM ~

1302
-'V4'

t. ~ ~ 4 1 ~I -

4 L4

- r-'-d

- p- ~'

POR OF LON BEACH

C A L~ I

p - * .~-.--.7t 011~

Fiur 3. Por ofLngBah,18

30
NATURAL CONDITIONS FACILITATING PORT DEVELOPMENT

San Pedro Bay is located in the southeast region of the Los Angeles

Basin, a gentle sloping basin approximately 50 miles long and 20 miles wide,

trending northwest, containing thousands of feet of sediments overlying a

crystalline basement rock (US Army Corps of Engineers 1984b).

In Long Beach Outer Harbor, the sediments are fairly uniform consisting

of a veneer of loose to firm surface sediments overlying very dense older

(Pleistocene) sediments. The veneer consists primarily of silts with isolated

lenses of sand. The older stratum consists mostly of sands with some lenses

of silt, clay, and shales to at least a depth of -150 ft mean lower low water

(MLLW). The near-surface materials in the middle and inner harbors are similar to the outer harbor, except that the top 6 ft contain more organic residue

(US Army Corps of Engineers 1984a).

Successful use of dredged material for landfill depends on the type of

sediment dredged. The Los Angeles Basin, being a desert area, has dry sandy

soil--an attractive advantage over moisture-holding sediments found in many

other port areas of the United States. In addition, the harbor's distance

from the mountains is such that the sediments settling out from the rivers are

a desirable size and strength for use as landfill. The abundance of fine- to

coarse-grained sand in the harbor has been a valuable asset for the Port. The

diminishing supply of this resource as an ideal material for landfill use is

an ever-growing concern among port planners and engineers.

Subsidence in the harbor has caused extensive damage to buildings, docks,

pipelines, and other facilities. It has also created deeper channels, which

are a welcomed by-product of this otherwise devastating occurrence. This subsidence was caused by extraction of oil from the Wilmington Oil Field. Between 1928, when pumping was initiated, and 1965, up to 29 ft of subsidence

and substantial horizontal movement occurred. Since 1966, subsidence has been

arrested by the injection of water into the oil zone, thus preventing the

soils from compacting when oil is removed. Due to the injection, some rebound

has occurred, reaching a maximum of 1.4 ft between the peak rebound years of

1961 and 1973. Currently, the maximum ground surface elevation fluctuation is

less than 0.2 ft annually and generally not measurable (US Army Corps of Engineers 1984a) (Figures 4 and 5).

Another advantage of the geographic location of the Port is the minimal

need for maintenance dredging due to the natural barrier created by the Palos

Verdes Hills, located west of the harbor, and the redirection of river outlets

away from Port channels by flood control facilities. The annual average maintenance dredging cost for the Port of Long Beach is $72,000, which is substantially lower than that for other US ports (Long Beach Harbor Consultants

1976).

The Port of Long Beach has also been very fortunate in that it has not

had to alter or deter dredge and fill projects because of the existence of

toxic substances. The US Environmental Protection Agency (EPA) requires that

chemical analysis be conducted on the material to be dredged to determine the

levels of concentration of certain constituents which may be toxic to marine

304
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organisms. The analyses are required from the areas proposed to be dredged on

samples obtained between the existing sediment surface and the proposed project dredge depth.

Prior to bioassay test requirements, maximum concentration levels were

allowed by the EPA for certain constituents. These levels were as follows:

mercury, 1.5 parts per million (ppm); cadmium, 3.0 ppm; lead, 180 ppm; zinc,

300 ppm; and oil and grease, 4,000 ppm. In a report prepared for the Port by

Long Beach Harbor Consultants in 1976, 200 separate samples were collected and

analyzed from over 40 stations throughout the harbor and outside the Federal

breakwater (Long Beach Harbor Consultants 1976). Concentrations of each constituent tested were less than or equal to the maximum allowable limits at all

stations except for three stations located in the inner harbor. However, the

inner harbor has not been used as a source of landfill material since 1924.

See Figures 6 and 7 which illustrate the dredge and fill history of the Port.

USE OF DREDGING AND LANDFILL IN PORT DEVELOPMENT

Hydraulic dredging and filling have been used extensively in developing

the existing harbor complex; approximately 50 percent of the Port's land area

in hydraulic fill (Johnson and Burke 1986).

Obtaining enough fill material for future development will require dredging the entire outer harbor and well beyond the existing breakwater. The Port

has been extremely fortunate in the past to have quality material readily

available for landfill; however, the supply of the best materials is nearly

exhausted. The Port will then need to consider transporting landfill from

offsite locations, or develop ways to make better use of the available dredged

material. One such technique, involving a special compaction process used

along dike perimeters, was tested and will be discussed later in this paper.

Water depths in the terminal approaches within harbor range from 50 ft in

the middle harbor basin and channels two and three, to 60 ft in the main and

back channels. Adjacent to berths, water depths range from 36 ft to 70 ft.

The deep berths and channels in the harbor can presently accommodate vessels

in the 50,000 to 165,000 DWT class with drafts not exceeding 58 ft. This is

an insufficient depth to accommodate the larger petroleum tankers and dry bulk

carriers. ARCO's terminal on Pier E, where depths are 70 ft, could handle

tankers up to 265,000 DWT, but the main channel depth is not sufficient to allow passage into Pier E. (See Figure 3 for channel reference.)

In the short term, our planned dredging of the main channel to a width of

approximately 1,000 ft and a depth of 76 ft will be necessary to provide improved access by modern cargo vessels presently constrained by draft limitations. Wharfside deepening will also be necessary to fully utilize deeper

channels. This dredged material will be used to create approximately

150 acres of new land for the Port (Port of Long Beach 1983).

2020 PLAN

Through extensive studies, it has been determined that San Pedro Bay, including both the Port of Long Beach and the Port of Los Angeles, will need an

additional 2,600 acres of land to help handle the anticipated 223,210,000

307
DREDGE ND FiLLEGENOR

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Figue 6.Drede an fil hisory,1907197

308:
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1976-1985

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Figure 7. Dredge and fill history, 1976-1985

309
short tons of cargo passing through the Ports by the year 2020. Not only is

the unavailability of land for expansion a problem, but the expected increase

in the size of cargo vessels will also require deeper port facilities.

Modernization of the existing facilities would result in a maximum capacity of only 150,127,000 short tons. This would require the ports to turn away

73,000,000 short tons of cargo because of a shortage of land (Port of Long

Beach 1984).

A master plan, called the 2020 Plan, has been developed to outline a program to meet the projected cargo handling needs of the Ports of Long Beach and

Los Angeles through the year 2020. The plan is a program of dredging, landfill, and facilities construction providing 2,600 additional acres of cargohandling facilities for both ports when completed. The plan also provides for

improvements of navigation channels in and around the outer harbor to allow

access by the largest vessels in the Pacific fleet. Channel dredging is proposed to a maximum depth of -82 ft, providing sufficient depths for liquid

bulk carriers in excess of 300,000 DWT. The dredged material would be disposed of in various harbor landfills, again using this valuable resource to

accommodate the maritime industry.

The 2020 Plan has been developed in conjunction with the US Army Corps of

Engineers and with the cooperation of both state and Federal agencies and numerous experts in dozens of specialties.

The Port zýf Long Beach will implement the plan in three phases: Pier K,

435 acres by the year 1995; Pier L, 450 acres by the year 2010; and Pier M,

300 acres by the year 2020 (Figure 8). The Port of Los Angeles will construct

its portion of the plan in similar phases.

CONSTRUCTION DESIGN

In the design of any shipside facility, a matter of major consideration

is the type of fill retention and wharf to be used. Several possible wharf

and fill retention schemes should be investigated to find which one best fits

the situation. This must take into consideration present and future shipping

conditions such as ship sizes, cargo loads, and cargo-handling methods.

Although we investigate new techniques each time a project is planned, we

generally conclude that a staged rock dike and hydraulic fill, along with a

concrete pile-supported wharf, is the most efficient and economic procedure.

This is principally because rock is readily available and within 22 miles by

marine transportation.

The general construction sequence at the Port is as follows: first, construct a dike or bulkhead vo enclose a proposed pier in sheltered water; second, hydrau•!cally fill the pier; and third, construct the wharf. Hydraulic

dredges pump the fill material for the piers from the ocean bottom. Rock used

in the Port is quarried from two quarries on Catalina Island. The weight of

the rock varies from approximately 135 pcf to 165 pcf, depending from which

pit the rock is quarried (Smongesky 1983).

310
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3115
Wharf on Concrete Piling Over Rock Dike

The pile wharf over a rock dike, shown in Figure 9, is the design we generally follow. The landfill that is constructed serves as a barrier to waves

and creates a quiet basin for wharf construction. This type of construction

is particularly economical when large quantities of rock and sand are readily

available.

z

_j 68,

EL.6 REINF. CONC. SLAB DRY FILL

EL.- 6' n.

3RD LIFT

E 'HYDRAULIC F

M LLW

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Figure 9. Pile wharf over a rock dike

Other Wharf Combinations

One of the wharf and bulkhead combinations that has been successfully

used at two piers in the Port is the pile wharf in combination with the sheet

pile bulkhead, as shown in Figure 10.

Steel sheet pile cellular bulkheads, another construction method, can be

constructed in open water. The steel sheet pile cellular bulkheads constructed in the Port are approximately 62 ft in diameter and are connected

with steel sheet pile arcs (Figure 11). The cells are constructed with

15-in.- wide sheets, 1/2 in. thick on the waterside of the cells and 3/8 in.

thick in~ the fill. The arcs are connected to the sheets with 1/2-in.-thick

tee-piles and are constructed of 1/2-in.-thick sheets.

The Port has constructed over a mile of concrete quay wall. This type of

wharf and bulkhead combination is shown in Figure 12. A careful analysis of

the soil should be made to determine possible slippage planes and allowable

toe pressures before determining whether a concrete quay is feasible as a

wharf and bulkhead structure for a particular site. Economics of marine concrete construction has prevented the Port from using this construction technique for many years.

312
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14W

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Figure 11. Steel sheet pile cellular bulkhead

313
_____ M HYDRAULIC FILL.

CYCLOPEAN CONCRETE

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Figure 12. Conccete quay wall

PIER J LANDFILL EXPANSION

The Pier J landfill expansion is the next anticipated major landfill

project in the Port (Figure 13). Work on this project is planned to begin in

early 1987. This expansion will add 147 acres of new land to the seaward side

of Pier J by placing 14 million cubic yards of dredged material behind multilift rock dikes (Figure 14). This construction will allow the Port to further

increase its container handling capability by providing backland to an existing container terminal and adding four new berths and an eighth container terminal to the Port (Port of Long Beach 1985).

As a result of the landfill, it is believed that some valuable coastal

marine habitat will be eliminated. The Port of Long Beach is undertaking a

wetlands restoration project to mitigate for these losses to fisheries. A

plan is under consideration to use the excavated material of the mitigation

site in the landfill of the Pier J expansion.

PIER A EXPANSION

A recently completed landfill expansion in the Port is the Pier A Project. This $50 million project added 24 acres of fill to the existing pier and

cleared the adjacent land of transit sheds and warehouses, converting the

breakbulk facility into an 88-acre container terminal. The landfill was supplied by the dredging of the Port's East Basin to a depth of 76 ft.

This expansion project involved the testing of a unique compaction technique. Following many years of laboratory experimentation and testing, a

technique for compacting dredged fill materials as they are being placed has

been developed. A full-scale field-testing program was conducted during the

hydraulic filling performed as part of the Pier A Expansion Project.

314
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M YDRAULIC FILL AREA

FUTURE-+%S ELEVATION

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PIER J LANDFILL EXPANSION

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HO 2-i29-I C APPOOICYC 1Y 01~ OF 1IC9u21(1110 OATE:jANUARI 98

Figure 13. Pier J landfill expansion

315
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316
Cort T. Johnson was the consulting engineer for this test, and GEOFON, another

engineering consulting firm, was retained by Mr. Johnson to independently

assess the geotechnical effects of the compaction test program (Johnson 1985).

This new system has been developed to compact sand, either clean or containing limited amounts of silt, in lifts several feet in thickness during

underwater placement. The method is similar to that of dry landfills where

compaction is performed in intervals rather than at the completion of filling.

The system provides a method of compacting fill material which underlies

successive lifts of dike rock in a multitiered perimeter dike (Johnson and

Burke 1986). Figure 15 represents a typical perimeter fill cross section.

Rock Dike Ref. Line CPs& Borings

______________ 0_107 •3~.6m 3 (1. )

Pierhead Line

EPile Row A

pprox. 1 ifective Copaton Zone

2' (0.6 mf)--- L --

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th Dpoi te end o 

Perim. 

esfs

cd to 3 thUncomoed ced

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Figure 15. Dike cross section

The test was perfoeed on the tops of three 13-ft lifts in a eest area

200 ft long by about 100 ft wide, and two lifts in an area of the same size on

the opposite end of the expansion site (Figure 16). The results of follow-up testing were most favorable, indicating that the relative densities of the

compacted areas were improved 14 to 32 percent over the uncompacted areas

(GEOFON, Inc. 1985).

It is believed by the Port of Long Beach that the effectiveness, practicality, and economy of the compaction system have been sufficient to warrant

its consideration for specific future projects (Johnson and Burke 1986).

Compaction is critical to the Port of Long Beach for several reasons.

The Port is situated in a seismically active area. Many experts believe that

if the fill can be adequately densified, especially along the dike, then the

potential for liquification to occur can be greatly reduced.

317
Test Pile No. 1

E. Compaction Area

Test Pile hio. 2• 3\ l ieEet 3-4

Pile Bents 123-134

(See Fig. k 3) +

Pile Bents 111-116

Test Pile No. 4 I

Pierhead Line

Rock Dike

C4 I Reference Line

Pier A Expansion Existing

1 I" Pier A

_375' 114.j_*

23+00

W. Compaction Area 2

CO•ACTION AREA LOCATIONS

Figure 16. Sand fill compaction area locations

The increase in soil strength caused by compaction is also a very important consideration. The Port plans to construct container terminals which require wharves capable of sustaining container stacking cranes and heavy truck

loads. Liquid and dry bulk terminals also require high soil strength due to

the heavy soil loads of the bulk warehouses and storage tanks. A cost savings

also exists in wharf construction when the soil strength is greater under and

immediately behind the dike. This extra strength allows for a steeper rock

face and a narrower, less costly wharf (Johnson and Burke 1986).

The potential savings in dike rock by reducing its penetration into the

supporting fill material have been estimated to amount to be about 7 percent.

318
This savings would approximately offset the entire estimated cost of compacting the perimeter fill, except for any added cost for placing the fill in

thinner lifts (GEOFON, Inc. 1985). This estimated saving is based on the situation existing with the Pier A Expansion Project.

As mentioned earlier, the Port is running out of quality landfill material. By creating densified soil under perimeter dikes, the interior area of

the landfill could be made up of a lesser quality landfill material; however,

ideally, a sandy material would be used throughout.

The application of this underwater compaction system would be contingent

upon the availability of sandy material for use in the landfill.

MITIGATION EFFORTS FOR HABITAT LOSSES

Port development, unavoidably, may permanently destroy habitat areas.

The Port of Long Beach seeks to minimize these habitat losses within its

boundaries whenever possible. Since there are no natural terrestrial habitats

of significant value, most efforts in this area are focused on marine habitats

(Port of Long Beach 1983).

The Port works with Federal and state wildlife agencies in determining

appropriate mitigation projects. Trade-off ratios for various marine habitats

and a formula for determining net biological impact from port developments are

considered.

Mitigation for marine habitat losses does not occur within the Harbor

District because this creation of a new habitat value may need to be destroyed

in the future due to further port development. It has been determined that

shallow, estuarine coastal embayment habitat in southern California, with its

relatively high value to marine fishes and migratory birds, has been reduced

in area at a greater rate than that of deepwater habitat (Board of Harbor Commissioners 1984). The Port, therefore, chooses to consider these shallow

sites for mitigation purposes.

Port development and related mitigation projects consume and create "habitat value credits" which are banked and subsequently debited from and credited to, with balances being carried over to future projects. The Port

entered into its first mitigation bank in March 1984 as a result of involvement with a two-phased restoration project totaling 30 acres in a location

approximately 20 miles south of the Port called Newport Bay. The Newport Bay

restoration site was a largely barren floodplain area above the reach of

tides, providing minimal habitat value. The fishery and waterfowl habitat

improvement at the site after restoration was predicted to be virtually

100 percent (Board of Harbor Commissioners 1984). The mitigation project is

now completed, and preliminary indications are that the project has been

successful.

The above-mentioned project was to mitigate habitat losses created by the

24-acre landfill expansion of Pier A. The expansion destroyed less marine

habitat than was created by the Newport Bay restoration project; therefore,

the Port now has a balance of 16 acres of habitat credits in its "bank."

319
In January 1986, the Port entered into its second mitigation banking

agreement to provide mitigation for the 147-acre Pier J Project. This mitigation project consists of restoration of approximately 110 acres of the National Wildlife Refuge in Seal Beach Naval Weapons Station (Figure 17). This

mitigation project is now in the design stage with construction costs estimated at $6 million.

Three areas will be excavated to suitable elevations, and tidal influence

will be restored to these areas. Natural colonization will then lead to the

development of a wetland community in those areas. Approximately one half of

the restored acreage will be permanently covered by water, providing valuable

fish habitat and resting and feeding areas for many species of birds, among

them the brown pelican. The remaining half of the area will consist of about

42 acres of intertidal mudflats and about 18 acres of isolated higher elevation areas covered by only the highest tides. The intertidal mudflats should

develop infaunal invertebrate populations and serve as feeding areas for fish

during high tides and for birds during low tides (Port of Long Beach 1985).

The task of finding new mitigation sites for future port development is a

difficult one. A review of wetlands in southern California reveals that there

are few places readily available for mitigation. Most of the larger areas

that have been identified as being suitable for mitigation of port projects by

the Federal and state wildlife agencies are either privately owned or military

properties. At present, the Port is awaiting the outcome of state and local

government negotiations with private property owners so that it can proceed

with future port development.

The shortage of available mitigation sites is a serious problem; port expansion may come to a halt if the wildlife habitat restoration requirements

are not met.

CONCLUSIONS

The Port of Long Beach has gone through many changes over the years, with

many more changes planned for the future. The need for extensive future development of the Port has been investigated thoroughly and confirmed. In order for the plans to be carried out, however, the problems of a lack of

suitable landfill and a scarcity of usable mitigation sites must be overcome.

The Port is developing feasible solutions to these problems, and it will pursue implementation of these solutions with a high regard for design and construction, maritime service, and environmental conditions, as well as a

consideration of local, national, and international interests.

REFERENCES

Board of Harbor Commissioners of the City of Long Beach, California Department

of Fish and Game, National Marine Fisheries Service, and Fish and Wildlife

Service. 1984 (Mar). "Memorandum of Understanding to Establish a Procedure

for Compensation of Marine Habitat Losses Incurred by Port Development Landfills within the Harbor District of the City of Long Beach," Long Beach,

Calif.

320
PACIFIC OAT RIAP

NAHEM BA -IIGTONPOJC

OOR POR OF LONG EACH30 EXPANSIO

RE?. ~ ~ RD S1-SIT TT FOAC

2.5OF WALPAOINIA

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3 03

i~e r...... ~ DTE: UNE198

Figure ~ AnhiMIymtgti ~ ~ 7. ~ SCL LpoEct

321NTYMA
GEOFON, Inc. 1985 (Sep). "Report of Geotechnical Study Underwater Compaction

Test Program, Pier A Expansion Project, Port of Long Beach, Long Beach,

California," Cypress, Calif.

Johnson, C. T. 1985 (Nov). "Final Report; Test Program on Dredged Fill Compaction at Pier A Expansion Project," Cort T. Johnson, Consulting Engineer,

Long Beach, Calif.

Johnson, C. T., and Burke, M. G. 1986 (May). "Underwater Compaction of Sand

Fill During Placement," Ports-86; Proceedings of a Speciality Conference on

Innovations in Port Engineering and Development in the 1990's, Ameriean Society of Civil Engineers, New York, New York.

Long Beach Harbor Consultants. 1976 (Feb). "The Port of Long Beach, Long

Beach, California, Environmental and Geotechnical Sampling Program; Volume II,

Environmental Data," Jack K. Bryant and Associates, Inc., Environmental Quality Analysts, Marine Biological Consultants, Inc., Converse Davis Dixon Associates, Long Beach, Calif.

Port of Long Beach. 1983 (May). "Port Master Plan Update - An Amendment of

1978," Long Beach, Calif.

Port of Long Beach. 1984 (Jul). "Executive Summary, 2020 Plan, Landfill Development and Channel Improvements for San Pedro Bay Through the Year 2020,"

Long Beach, Calif.

Port of Long Beach. 1985 (Dec). "Master Plan Amendment/Final Environmental

Impact Report, Pier J Landfill Project," Long Beach, Calif.

Smongesky, P. P. 1983 (Apr). "Port of Long Beach Chronological History,

1909-1982," Long Beach Harbor Department, Long Beach, Calif.

US Army Corps of Engineers. 1984a (Jul). "Appendices for Los Angeles - Long

Beach Harbors Channel Improvements and Landfill Development," US Army Engineer

District, Los Angeles, Los Angeles, Calif.

US Army Corps of Engineers. 1984b (Jul). "Draft Feasibility Study for

Los Angeles - Long Beach Harbors Channel Improvements," US Army Engineer

District, Los Angeles, Los Angeles, Calif.

322
u IMPACT ASSESSMENT OF IN-PLACE CONTAMINATED SEDIMENTS

T-0 ON WATER QUALITY: A CONCEPT

T T.L. Hart, D. Gunnison, J. Brannon

CO Environmental Laboratory in (D = US Army Engineer Waterways Experiment Station

Vicksburg, Mississippi 39180-0631 _

Q - ~ABSTRACT I

In the past, environmental assessments of US Army

Engineer Civil Works water resource projects that involve dredging of contaminated sediments have addressed only the consequences of dredged material

disposal. The environmental benefits that may be

incurred from the removal of in-place contaminated

sediments have not been considered. The deficiency in

evaluating the environmental consequence of sediment

removal has been due to the lack of a logical delineated approach to quantifying the impacts of contaminated sediments on water quality as well as the

reluctance of regulatory agencies to consider contaminated sediment removal as a benefit. This paper presents a conceptual approach developed for Civil Works

operations and maintenance navigation projects for

assessing the environmental consequences of in-place

contaminated sediments. The approach and the potential benefits are delineated.

INTRODUCTION

The Corps of Engineers (CE), as one of the Nation's major construction

agencies, is tasked with the responsibility for the constructicn and maintenance of over 25,000 miles of Federal channels, over 100 commercial harbors,

and 400 small boat harbors. The CE annually removes 250 to 300 million cubic

yards of dredged material. A small, although significant, portion of the

sediments dredged are contaminated and require special handling and disposal.

These sediments may contain a multitude of toxic materials, including polyaromatic hydrocarbons (PAH's), polychlorinated biphenyls (PCB's), heavy

metals, pesticides, and by-products of industry. These contaminated sediments

are normally associated with the Nation's urban industrial waterways, where

Federal channels act as catchment basins for sediments.

In constructing and maintaining these channels, the CE must comply with

Federal and state environmental legislation and evaluate the environmental

consequences of dredging and disposal of these sediments. In evaluating the

environmental impacts of dredging and disposal of contaminated sediments, the

major emphasis has been on the short-term impacts on water quality from dredging and the short- and long-term impacts on the environment from disposal.

323
Minimum attention has been given to either the environmental effects on the

water body of contaminated sedime-ats in Federal channels or the environmental

benefits that may accrue from sediment removal.

In the past, as well as today, strong public opinion is often expressed

against the removal and disposal of contaminated sediments. These objections

are based on the belief that the environmental consequence of sediment removal

and subsequent disposal exceed the social and economic benefits gained from

the project. Although polluted sediments are often located in highly industrial and urban areas, they are neither stationary nor inert. These sediments

continue to exert an influence on the water quality of the waterway through

oxygen demand and release of nutrients and toxic substances, as well as supporting only a limited pollutant-tolerant community of poor species diversity.

Further, the resuspension of these sediments by natural or man-induced causes

will not only affect the overlying water column, but may also impact water

quality for miles outside the immediate area of concern.

Polluted sediments are not confined to Federal channels and major harbors

in our urban and industrial areas. Spills from chemical and petroleum barges

and small chemical and petroleum terminals have resulted in localized pockets

of contaminated sediments in areas far removed from our major metropolitan

areas. Runoff from agricultural and timber lands also introduces pesticides

and nutrients to the Nation's waters, often resulting in river, reservoir, and

estuary sediments becoming contaminated. Point discharges from feedlots,

chemical companies, and city sewage treatment plants have also been a source

of nutrients and contaminants that have affected sediments. Many of these

polluted sediments are located within Federal water resource projects built

and maintained by the CE. The effects of these sediments on the continued

operation and maintenance of these projects, as well as proposed modifications

to current use, can be significantly affected by the presence of contaminated

sediments.

For a more complete assessment of cost versus benefits associated with

maintaining specific water resource projects, the impacts of in-place sediments on the environment must be considered. If the CE can determine and

quantify the impacts, the "true" cost of the project's social, economic, and

environmental attributes can be determined.

This paper presents an approach that can be used in the planning and

assessment of water resource projects to evaluate the environmental impact of

contaminated sediments on water quality. This approach will be presented

along with a list of potential activities and associated benefits.

BASIC CONCEPT

The basic idea is to allow the project planner the ability to identify

and quantify environmental impacts from in-place sediments on the water quality of the water body, thereby allowing for an accurate evaluation of the

project cost versus benefits from removing the existing sediments. Various

factors will influence this assessment, including sediment characteristics,

concentration and type of contaminants in the sediments, system hydrodynamics,

contaminant sources, and existing and proposed uses of the water body. These

and other factors will significantly affect the identification and quantification of impacts. Although many of these factors can be determined through

324
existing data and information, others will require data collection and analysis. Without a delineated approach that provides a logical and systematic

procedure to assess in-place sediments, the results may be of limited value

due to misdirected efforts or inadequate data and analysis.

ACTIVITIES

Assessment of in-place contaminated sediments has a number of applications. Listed below are potential applications where the CE has direct responsibility or is involved as a cooperating agency.

Federal operation and maintenance navigation

Permit activities

Superfund sites

Reservoirs

Toxic spills and hotspots

BENEFITS

Five basic benefits can be incurred from the assessment of in-place sediments. These benefits, although not associated with each of the above-cited

activities, will provide for an improvement in the CE's ability to construct

and maintain water resource projects. These basic benefits are:

a. Quantify existing conditions, thereby providing a baseline for

decisionmaking.

b. Provide a baseline to assess the potential benefits and costs

associated with each proposed alternative.

c. Quantify project benefits incurred from removal or modification of

in-place contaminated sediments.

d. Provide for quantification of project costs and benefits gained for

the proposed action.

e. Provide a baseline for assessing not only short-term but long-term

benefits and costs from various long-term management strategies.

APPROACH

The conceptual process of developing and implementing an assessment protocol for in-place sediments is presented as a three-phase approach. Each

phase consists of a series of steps or essential activities that lead to the

development of specific data and information necessary to determine the impact

of the sediments on water quality. The intent of this process is to quantify

costs and benefits associated with specific alternatives as they relate to impacts from in-place contaminated sediments.

Phase I

Phase I is intended to serve as the first level of assessment. At a minimum, this phase requires the defining of assessment objectives (e.g., cleanup

and alternative evaluation), thereby determining the level of data requirement

325
and analysis for decisionmaking. Once the objectives for the assessment are

defined, the next step is the identification and collection of existing data.

There is usually a wealth of information available from various Federal and

state sources. The intent under Phase I is to minimize field data collection

activities; so, a decision is needed as to the sufficiency of the existing

data for evaluating the impact of in-place sediments. If existing data are

insufficient, data gaps are identified, validated, and screened based on factors such as potential for development and time and resources needed to fill

the gaps. If the needs are valid, a data collection effort is planned. Unvalidated requirements result in either no further evaluation of the in-place

sediments or a reassessment of the study objectives. Once the initial data

requirements are met or, if necessary, additional data requirements identified, Phase I is completed.

Phase II

Phase II consists of collecting required additional data and conducting a

data analysis of sufficient detail to evaluate the impact of in-place sediments as they relate to the objectives delineated under Phase I.

Phase III

Phase III uses the results obtained under Phases I and II to conduct the

detailed evaluation as required to address the study objectives. This process

will occur in conjunction with alternative evaluations that consider engineering, economic, social, and environmental cost and benefits.

Alternatives

In addition to Phases I through III, consideration must also be given to

implementation of any alternative or proposed actions and monitoring of the

results. Without a feedback mechanism, the validity of the analysis of both

the impact of in-place sediments on water quality and the benefits from their

removal or alteration cannot be fully known.

SUMMARY

The paper presents a concept that can be used by CE planners to identify

and quantify environmental impacts on a water body from in-place contaminated

sediments. This concept is applied through a three-phase approach that allows

quantification of cost and benefits associated with in-placed sediments and

proposed actions. By using a three-phase approach that incorporates the maximum use of existing data during Phase I, cost for field data collection and

analysis can be kept at a minimum. Further, by using a phase approach, decision points can be incorporated during each phase for assessing proposed benefits to be gained from collection and analysis of additional data which may be

disproportionate to the incurred cost.

326
PRELIMINARY STUDY OF THE ECOLOGICAL STRUCTURE OF

BENTHIC ORGANISMS IN TOKYO BAY

S. Sekiguchi, Y. Hirai

Environment Division

Second District Port Construction Bureau

Ministry of Transport

M. Yoshida, K. Irie

Japan Bottom Sediments Management Association

ABSTRACT

The benthic organisms and environmental conditions of Tokyo Bay were surveyed to determine the ecological structure of the bottom layer of the Bay. The

results of the surveys showed that water and bottom

sand qualities tended to worsen toward the inner part

of the Bay, and benthic fauna became more simplified.

A study on the correlation between benthic organisms

and environmental factors such as chemical oxygen

demand and total sulfide of the bottom deposits indicated a specific range of environmental conditions for

each benthic organism. The result of the trawling

survey indicated a relatively simple food chain relationship at the innermost part of the Bay: bottom

detritus - polychaeta -- marbled sole. The relationship tended to be more complicated toward the outer

part of the Bay.

BACKGROUND

Tokyo Bay is a calm water area of 120,000 ha with an average depth of

15 m situated at the center of Honshu, the mainland of Japan. Figure 1 shows

the geographical features of the Bay. The metropolitan area with its population of 28 million surrounds the Bay. The Bay serves as fishing grounds, navigation routes, and recreation.

The environmental condition of the Bay has been deteriorating with the

rapid expansion of the metropolitan area, especially since 1959 (Figure 2)

though many countermeasures such as extension of the sewage systems have been

taken.

Chemical factors have been primarily used in the environmental assessment; few attempts have been made to assess changes in the environmental condition from the biological point of view. In the present study, a biological

approach was taken to tackle the environmental problem in the Bay. Ecological

aspects of benthic organisms in the Bay were studied as the first step.

327
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METHODS AND RESULTS

Field surveys were made on water and bottom qualities and on benthic organisms at four stations: the innermost part of the Bay, the central part of

the Bay, the mouth of the Bay, and the tidal flat. The depth was 10 m for the

first three stations (Figure 3). Figure 4 illustrates the survey method, and

Figure 5 shows the flowchart of analysis of collected data. Surveys were carried out from 21-26 January 1986.

M TOOTidal flat I 0 of Kasai. 2.

Offshore of Ka"i.

Innermost part of .Tokyo Bay

Offshore of Banzu.

Central part of Tokyo Bay 3.

KISARAZU

Nagaura at the stations

4. mouth of Tokyo Bay FUTTIP

0 10 to

Figure 3. Survey stations

Tables 1 and 2 show the results of the surveys on water and bottom

qualities.

For meiobenthos and macrobenthos collections, bottom sediments sampled by

a core sampler were sifted through sieves (mesh size: 105 V for meiobenthos

and 1 mm for macrobenthos). Organisms found were identified, counted, and

weighed (wet weight). Results are shown in Table 3.

329
Transparency measure

Observation :1lon g the lin

Survey on water quality /

~ ~ - -Survey using trawling net

Figure 4. Schematic diagram of the field survey

Megalobenthos and benthic fish were collected with a trawling net to

study species composition, standing stock of each species, and their food

habits. The organisms collected were identified, counted, and weighed (wet

weight). For benthic fish, stomach contents were also analyzed to study food

chain relationships between other bottom organisms. Table 4 shows the dominant species of fish collected at each sampling station. Food habits of representative fish species are shown in Table 5.

ANALYSIS

Relationship Between Environmental Factors and Organisms

The correlations were studied between three properties of bottom sand:

median value of sand particle diameter, COD, and T-S (Table 6). Some of these

are illustrated in Figure 6. Among the dominant species of macrobenthos and

meiobenthos, the species with open circles in Table 6 are dominant only in

limited ranges (shown in parentheses) of bottom sand properties. Positive or

negative correlations were observed between some items and the bottom sand

properties and are indicated with + or - in Table 6.

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TABLE 1. WATER QUALITY (DATE OF THE SURVEY: 21-26 JAN. 1986)

Area Depth Trans- Water Salinity pH COD DO SS T-N T-P POC PON

parency temp.

m m 0C mg/i mg/i mg/i mg/i mg/i mg/i mg/i

Tidal 1.0 8.4 30.38 8.3 3.4 11.3 14 1.52 0.095 1.17 0.19

fiat 1.8 1.8 8.4 30.37 8.3 2.9 11.1 7 1.45 0.100 1.23 0.21

2.6 9.4 30.72 8.3 2.8 10.1 7 1.46 0.090 1.05 0.15

Inner- 1.0 8.1 30.61 8.4 3.1 11.6 7 1.55 0.090 1.07 0.18

most 5.7 1.9 8.1 31.99 8.5 2.9 12.9 9 1.05 0.050 0.96 0.14

10.3 10.7 33.25 8.1 2.2 7.0 4 0.76 0.064 0.71 0.10

Central 1.0 9.0 32.55 8.2 2.1 11.5 5 0.72 0.057 0.53 0.06

4.2 2.2 9.0 32.57 8.3 2.2 10.5 3 0.79 0.054 0.70 0.11

7.3 9.0 32.44 8.3 2.2 10.6 4 0.70 0.055 0.80 0.13

Mouth 1.0 8.6 32.56 8.3 1.7 10.7 4 0.78 0.062 0.59 0.09

5.2 3.7 8.6 32.59 8.3 1.7 10.0 4 0.77 0.058 0.87 0.13

9.3 8.6 32.58 8.3 1.7 10.7 5 0.78 0.053 0.74 0.13

TABLE 2. BOTTOM QUALITY (AVERAGE OF THREE SAMPLES)

Area Median of Ignition ORP, mV COD T-S T-N T-P

particle loss - z 0-5cm 5-10 cm mg/g* mg/g* mg/g* mg/g*

Tidal 0.21 1.7 -94 -95 2.5 0.06 0.21 0.33

flat

Inner- 0.0042 9.5 -104 -120 32.5 1.74 1.85 0.84

most

Central 0.24 2.5 -136 -150 7.0 0.09 0.73 0.18

Mouth 0.073 7.2 -103 -113 23.0 0.53 1.77 0.43

. Dry weight

The dominant species of macrobenthos and melobenthos appeared in specific

ranges of bottom sand properties. They are classified as follows according to

the eutrophication scale by Yoshida (1983):

a. Mainly in saprobic areas (COD: more than 30 mg/g, sulfide content:

more than 1.0 mg/g):

Paraprionospio pinnata (Figure 6a)

Foraminiferida

Prionospio cirrifera

332
TABLE 3. RESULTS OF BENTHOS SURVEY*

Unit: macrobentlhos; per 0.28m2

meiobenthos ; per 30cm2

Area Number Number Wet Dominant Species (ratio)

of of weight

species indiv.

Macrobe.thos

Tidal 38 1,428 51.58g Armandia sp. (25.12)

flat Capitellidae (15.22)

Ancistrosyllis hanaokai (10.42)

Inner- 15 1,391 48.58 Paraprionospio pinnata (92.42)

most

Central 42 5,862 1066.72 N Musculus senhousia (94.3%)

Mouth 44 642 27.34 g Lumbrineris longifolia (36.4%)

Polydora sp. (7.82)

Cirratulidae (6.22)

Meiobenthos

Tidal 10 5,038 33.4 mg Nematoda (91.8%)

flat

Inner- 7 2,527 44.9 mg Nematoda (80.8%)

most Foraminiferida (14.0Z)

Central 15 2,128 26.4 mg Nematode (88.32)

Harpacticoida (7.12)

Mouth 16 1,600 26.8 mg Nematoda (79.22) Harpacticoida (1.4.12)

TABLE 4. DOMINANT SPECIES COLLECTED BY TRAWLING

Area Fish Other Organisms

Tidal flat Limanda yokohamae Ciona robusta, etc.

Innermost Limanda yokohasmae Styela plicataec.

Central Limanda yokohamae Mytllus edulisetc.

Repomucenus valenciennei.

Mouth Leiognathus nuchalis Crangon affini, etc.

Acanthopobius flavimanus

Ditrema teminncki

333
TABLE 5. STOMACH CONTENTS OF THE DOMINANT FISH SPECIES COLLECTED

Area Fish Stomach Contents

Tidal flat Limanda yokohamae Neanthes Japonica

Other Polychaeta

Innermost Limanda yokohame Paraprionospio pinnata

Other Polychaeta

Central Repomucenus valenciennei Theora lata

1lexagrammos otakii Sardine and other fish

Sepiolidae

Limanda yokohamae Paraprioiiospio pinnata

Lumbrineris sp., etc.

Mouth Repomucenus valenciennei Theora lata, etc.

Acaithoogobius flavimanus Theora lata

Polychaeta, etc.

Ditrema temmincki Gammaridea

_1 Caprellidea

b. Mainly in hypertrophic areas (COD: more than 25 mg/g, sulfide content: 0.3-3.0 mg/g):

Lumbrineris longifolia (Figure 6b)

c. Mainly in eutrophic areas (COD: 5-25 mg/g, sulfide content:

0.03-0.3 mg/g:

Musculus senhousia (Figure 6c)

d. Mainly in oligotrophic areas (COD: less than 5 mg/g, sulfide content: less than 0.03 mg/g):

Ancistrosyllis hanaokai

Aonides sp. (Figure 6d)

Cirriformia sp.

Capitellidae

The number of species (Figure 6e) and species diversity index (Figure 6f)

tend to decrease with increments of COD and T-S. As the bottom sand becomes

seriously polluted with organic matter, common bottom organisms disappeared

and, instead, highly tolerant species such as Paraprionospio pinnata become

dominant, thereby simplifying the fauna of the area.

Estimation of Food Chain Relationships

Prey-predator relationships at each sampling station are estimated from

the results of the surveys (Figure 7). In the figure, the thickness of lines

represents frequencies of relations.

The fundamental food chain relationship at the innermost part of the Bay

was that of marbled sole (Limanda yokohamae) on polychaetes such as

334
TABLE 6. CORRELATIONS BETWEEN BENTHOS AND BOTTOM SAND PROPERTIES

Item Median of COD T-S

Particle Size

mm mg/g mg/g

Dominant Ancistrosvilis hanaokai 0(0,20-0.21) 0(less than 4) 0 (less than 0.1)

species Nectoneanthes latipoda x x x

of Lumbrineris longifolia 0(0.05-0.10) 0(15-30) 0(less than 0.7)

macro- Aonides sp. 8(0.21) 0(less than 5) 0 (less than 0.4)

benthos Paraprionosplo pinnata 0(]ess than 0.01) 0(more than 30) 0(more than 1.0)

Cirriformia sp. x - 0(]ess than 0.6)

Capitellidae 0(0.20-0.21) 0(less than 4) Q(less than 0.2)

Sabellidae x x x

Musculus senhousia 0(0.23-0.25) 03.5-15) 0(0.05-0.3)

phiura linberi 0 (0.05-0.10) 0(15-26) 0(0.3-0.6)

Dominant Foraminifera O(less than 0.Ol O(more than 30) 0(more than 1.0)

species Nematoda O0(0.15-0.25) x x

of Prionospio cirrifera - + 0(0.2-2.0)

meio- Harpacticoida a Q(less than 30) Q(less than 0.7)

benthos

Macro- Number of species +

benthos Number of individuals + a x

Wet weight + a x

Meio- Number of species x x x

benthos Number of individuals x x x

Wet weight x x x

Indexes Biotic index x x x

for Average diversity index; D x x x

macro- Relative diversity index; B. x x x

benthos Total diversity index; I +

NOTE: 4 = positive correlation; - = negative correlation; 0= dominant species only in limited

ranges (shown in parentheses); x = ?

Indexes are calculated as follows: Biotic index - N/S Dn -L loge n

N nl! n2 l . .. S

Db = I_ loge N! = I I loge N! - NxDn

NlogeS nl? n 2 ! ..... ns! loges lS! nl! "2! ......... 

Where N-total number of individuals, ni- number of individuals of i-th species, S=number of species.

All numbers are per 0.09 m2 .

Neanthes japonica and Paraprionospio pinnata which feed on organic deposits on

the bottom. However, at the central and mouth sections of the Bay, fat greenling (Hexagramrnos otakii) feeding on nektons and surf fish (Ditrema temmincki)

feeding on crustaceans appeared as important predators, and the variety of

preys increased accordingly. It is clear that predators and their food habits

become more diversified from the innermost to the mouth of the Bay.

For megalobenthos different animals with different food habits were also

observed at the innermost and outer sections of the Bay. At the innermost

Bay, mussel (Mytilus edulis) and sea squirts (Ascidacea) which fed on suspended matters were abundant, whereas starfish, shrimps, and crabs with carnivorous or omnivorous food habits appeared at the central and mouth sections

of the Bay.

The route of the organic matter and nutrient circulation system is

proposed to be: organic matter deposits at the bottom - macrobenthos -

335
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336
benthic fishes such as marbled sole (Limanda yokohcmae), store flounder

(Kaeius bicoloratus), whipfin dragonet (Repomucenus valenciennei) and goby

(Acanthogobius fravimanus) in Tokyo Bay.

FUTURE PROSPECTS

Few ecosystem studies have been made on Tokyo Bay. The present study was

conducted to determine the structure of the benthic ecosystem in the Bay as

part of an integrated assessment of the area.

Biological surveys are influenced by more sources of errors in sampling

procedures or in dealing with the results, when compared with physical or

chemical surveys. Thus, the first step to be taken would be to decrease

errors through repeating surveys. In practice, sampling should be done more

frequently to decrease the error due to time factors. Most benthic organisms

propagate in spring, and low oxygen content of the water mass occurs in the

summer in Tokyo Bay. It would be necessary, therefore, to closely repeat surveys in these seasons, together with the year-round surveys.

Indicator species corresponding to a certain ecological feature may be

established based on the results of the present study and other surveys.

337
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