SILTPROTECTOR®

PREVENT DIFFUSIONOF SILT IN WATER

TAIYO KOGYO CORPORATION

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Iribules

Silt Protector is a flexible membrane

product that has been designed to

physically prevent diffusion of pollution

generated in dredging or reclamation

works on the seas or riverso

eFunction of Silt Protector

The pollution (fine particles) is said to

badly affect the benthic organisms

(marine life that live in the bottom)

including making the breathing of fishes

diHicult and reducing underwater

illuminanceo The Silt Protector prevents

diffusion of pollution safely because it

usesa physical means without using

chemicals that will be the cause of the

secondary pollutiono

The Silt Protector basically consists of

the curtain section that is made of

synthetic textile (mainly polyester), the

float that hangs the curtain in the water,

and the mooring section for hing the

unit at a specified locationo

Projects

·'ronmenloDama.ging E

Models andFeatures

The Silt Protector consists of several

types that are individually subdivided

into some ranks so that the user is able

to select units best suited to specific site

conditions and work items. The Silt

Protector con be used individually or

separately, or by combining the units.

eFixed Hanging TypeSilt Protector

This type is used the most frequently.

It basically consists of floats on the

surface and curtain and weight chain

below the surface. One span of this

product is 20m long. It is moored to the

bottom through anchor ropes and

anchors at every 19.5m point.

The anchor ropes are steel wire type or

synthetic fiber type, and anchors are

concrete blocks, usually.

when this product is used under high

wave conditions, the curtain with the

verticallength of lOm or less is used

and standing type is used together in

many cases. wh en wave is low, the

curtain of 20m long or more may be

used.

The fixed hanging type Silt Protector is

classified into four ranks, A, B, C and D

so that a type best suited to a specific

application con be identified.

3

.General site condition for

hanging fixed type

Standerd specifications

Rank

A

B

(

D

Suitable site conditions

Area outside of breakwater

.Wave height: 1.Sm or less

.Velocity of current : O.Sm/ sec or less

Wide area inside of breakwater, or inside of inlet that is

sheltered by the natural submarine topography

.Wave height : 1.0m or less

+Velocity of current : 0.2m/sec or less

Area with medium extent inside of breakwater

.Wave height : 0.8m or less

.Velocity of current : 0.1 m/ sec or less

Lakes, or weil sheltered area as colm as lakes

.Wave height : O.Sm or less

.Velocity of current : O.OSm/sec or less

Float dia(mm)

600

400

300

300

Float type

Unspaced

Unspaced

Unspaced

Spaced

Curtain material

spo- # 800 or 500

spo- #500 or 300

spo- #500 or # 300

spo- # 300

(hain weight(kg/m)

10

S

S

3

• Remarks *Standard unit length is 20m.*Anchor is not included in the unit.

Without Silt Protector

Distance trom source

EFFECT

Silt Protedor generally provides the

following effeds on prevention of

diffusion of pollution in the sea .

• Acceleration of settlement of

silt by interference of particles

Installotion of the Silt Protedor

suppresses diffusion of the pollution and

make the soil particles interfere with

each other to accelerate their settlement.

4

No Silt Protector

With Silt Protector

].Reduction of distance required

to settle the silt

Installotion of the Silt Protedor as shown

narrows the settlement range, resulting

in minimizing the diffusion of pollution

after the unit.

More Types

.Frame type Silt Protector

This type hos been designed to en close

loco 1 pollution caused by the grab

dredging. It consists of floats (usually

discharge pipes are used), curtain and

ballast at the bottom. Mid-ballast may

be added as necessary. Many of this

type is made so that the length of the

curtain con be changed according to

the depth by using an winch and wire

rape. The length of the curtain is made

less than 15m for eosier used on the

grab dredger.

Direction of Flow----.Combined installation

820m

..._______HangingType

460m

J/Sinkable Type

Grab Dredger

Frame Type =m/Standing Type

rFrame type Silt Protector is, in many

cases, installed together with hanging

type to avoid turbid water when

dredger moves, tucking up curtain.

For deep sea like 20m water depth,

combined installotion of hanging type

and standing type is sometimes used.

In case, boot passing is necessary,

sinkable hanging type is used for open

part.

5

G

.Standing Type Silt Protector

The standing type Silt Protector hos

been developed to prevent diffusion of

pollution that may occur near the

bottom in dredging or dumping of soil.

This type consists of an anchor{normally

steel H beam is used), curtain and float

that pulls up the curtain with its

buoyancy. The diameter of generally

used float is 300mm(spaced type), and

one span of this type is 20m long.

In many cases, this type is used together

with the hanging type product .

• Sinkable Hanging TypeSilt Protector

The sinkable hanging type Silt Protector

is used when it is necessary to make an

entrance/ exit for the passage of vessels

that enter into or exit from the

reclamation area. The fundamental

construction of the sinkable hanging

type Silt Protector is similor to the fixed

hanging type Silt Protector except that

the float is inflatable.

The float is hollow and is made of

synthetic rubber.

When making this unit afloat on the

water, the float is inflated by charging it

with air, that con be completed in a

very short time. The unit con be sunk

immediately by deflating the float.

The typical case of application of the Silt

Protector is the reclamation of artificial

island.

ApplicationCross SectionPollution Removal Rate (%)

21m

1~1100ml

300m

I70 - 15.Type of work I

I 70X 100 = 78.6

-_10m

60 - 12X 100 = 80.87015 8 4 60

Dredging

IÁ ::12

7 5 50 - 12X 100 = 76.0*Culter suction dredging

128 5 50

*Grab dredging

8015 10 6 80 - 15X 100 = 81.3ppm

80

*Hopper suction dredging

Offshore dumping

eUpper layer, lef! side

41.0-14.3*from hopper barge12mJ~1 TI 12m I

41.0X 100 = 65.1

*from hopper suction dredger

r_2ml~l~eUpper layer, right side36.4 - 14.1 X100=61.336.4

Reclamation

14.341.043.6 36.414.113.816.6

eMide layer lef! side*Substitution for dike

20.237.634.6 35.118.125.829.1 37.6 - 20.237.6

X 100 = 46.3

*Spillage drainage

50.775.5 ppmeMide layer right side35.1 - 18.1 X 100 = 48.435.1

120m

Pollution removal rates shown in the above table are data taken from actual sites.

200 U 37T uroulence caused by dumping trom barges

172 9

ppm

172 - 9172

200 - 37200

X 100 = 94.8

X100=81.8

7

( •eExamination Flow

It is recommended to follow the flow

described here to make the planning

of installotion of Silt Protector .1•.e~illlll[.lj[.]I~r::r.Ir-TiI

••l lt}f:lm[.Jo.~1jlll[.Ii~rnn~r::r.Ir.TiI J•••~ lrnt'Ej~~ J

• Design conditions

*Wind velocity

*Current velocity

*Wave height

*Wave period

*Wave length*Bottom soil

* Period of use

*Water depth

* Tidal range

• External force

The design extern ol force, W, applied to the

Silt Protector is divided into the following

three types of horizontol pressures.

Pressure !rom Aow Wl

Pressure !rom wove W2

Pressure !rom wind W3

eStructural Analysis

The specifications for the Silt Protector to

be used are determined based on the

externol conditions of the site such os

wind speed, current speed, wave height

and depth of water by using 0 specified

structurol calculation.

~I .• Estimate conditions • Typical diffusion of pollution

* Area of work

*Work item

* Dredging rote

*Working hours

*Operotion period* Soi! dato

* Target value of SS

*Current velocity

*Water depth

Souree of PollutionDownstream Direction

eDiHusion Estimate

Taiyo Kogyo Corporotion theoretically

estimates the diffusion of pollution in

case no Silt Protector is used, and effect

of Silt Protector.

8 Examination

Installation

elnstallation works forFixed Hanging TypeSilt Protector

Preparation

*Preparation of working yard

*Making anehor bloeks

*Bring materials to the site

Assembling on the land

* Inspection

*Series eonnection of spans

*Temporary tueking up of eurtains

Installation works on the sea

* Loading on the barge

*Towi ng barge

*Plaeing anehor bloeks

* Installing Silt Protertor

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• Specifications for the curtain material

SPO-#300 rrf T~~silestr~ngh I 300kgf!~c~1 t

IIIfIIIIIIII:~ jL ~

SPO-#800

I Tensile strengh I 800kgf/3cm I

SPO-#500

[T ensile str~!ni!hI 500kgf!3cm~

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eMaterial for curtain and

float components

The curtain and inner cover for the float

are made of high strength polyester

synthetic fiber that hos been studied and

developed to give excellent durability,

cold-resistance, chemical resistance and

light resistance.

The float cover{outermost cover) is made

of high strength polyester tarpaulin with

superior UV (ultra violet ray)resistance in

addition to the features of the polyester

synthetic fiber.

The float is made of solid cylindrical

styrene foam with high weather

resistance. Since the material will not

absorb water, the buoyancy of the float

is not reduced. The float adapts to the

wave weil thanks to the advantage of

the materia!.

10 Material

.a~ (EUROPE) B.v.~EOPEX ~~~~~~,~~30 ~ ~~ugg~~~á~~(NL)Middelblok 164, 2837 327+3118237Tel. + 31 182377 329

Fax pex com"I europe@geo .E-mal comInternet www.geopex.

T AIYO KOGYO CORPORA TION

Singapore Representative OfficeNo.1,Science Center Road The Enterprise #09-60,Singapore 609077Tel: +65-6822-6293 Fax: +65-6822-6294Email: EM002923@MB.taiyokogyo.coJpWebsite : http://www.taiyokogyo.co.jp/sipro/Frames/Fdefault.htm

Tokyo Office2-33-16,lkejiri,Setagaya-ku,TOKYO154-000 1,JAPANTel: +81-33714-3366 Fax: +81-33791-5454

Email: NI000263@MB.taiyokogyo.co.jpWebsite : http://www.taiyokogyo.co.jp

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No.2004-400-0023 2004.4.2000