•

.+ Environment Canada Environnement Canada

Fisheries Service des peches and Marine Service et des sciences de la mer

Assessing The Impact Of A 24" Suction Pipeline Dredge On Chum $almon Fry In The Fraser River

by L.K. Dutta P. Sookachoff

Technical Report Series No. PAC IT - 75-26

Southern Operations Branch

Pacific Region

132 L( 3

ASSESSING THE IMPACT OF A 24" SUCTION PIPELINE DREDGE

ON CHUM SALMON FRY IN THE FRASER RIVER

by

L. K. Dutta and P. Sookachoff

Technical Report Series No. PAC/T-7S-26

Environment CanadaFisheries &Marine ServiceHabitat Protection UnitSouthern Operations BranchPacific Region

TABLE OF CONTENTS

Lis t of Fi gures

List of Tables

Summary

Introduction

Preparations for the Tests

Tests Procedures

Resul ts

Discussion of Results

Recommendations

Appendix

Bibliography

Acknowledgements

PAGE

ii

ii

iii

1

3

8

14

17

19

20

23

24

i

1.

2.

3.

4.

5.

6 .

7.

8.

9 .

10.

11.

I

II

III

LIST OF FIGURES

Test Site and Dredge Location

DPW 322 in OperationDPW 322 With Cutterhead raisedabove Water Level

Float Mounted Live Cages

Holding Tank Containing Live Frybeing transferred to Dredge

Counting Fish

Monitoring Miniature Settling PondOutflow

Transfer of Retrieved Live Fry toHolding Cages

Inserting Fry into Suction Pipe onDredgeMain Settling Pond

Main Settling Pond Outlet Structure

LIST OF TABLES

Summary of Fry Mortality

Fry Recovered During MonitoringOf Spoil Are as

96-Hour Viability Test of ControlFry And Fry Retrieved From SpoilAreas

PAGE

3

5

5

6

7

8

9

10

11

12

13

PAGE

14

15

16

ii

iii

SUMMARY

The Fisheries and Marine Service, in cOllaboration with

Public Works Canada conducted a test at Annacis Island to

assess the effects of a Hydraulic Suction Dredging operationon seabound juvenile salmonids on May 10, 1974.

Known numbers of chum salmon fry were inserted into the

suction pipe of an operating dredge and were recovered at thespoil site. A 96-hour viability test was conducted on those

fry recovered alive at the spoil run-off outlet to ascertainthe number of fry that would survive after passing through a

dredge and land disposal system.

The following results were obtained:

1. It was observed that for every fry recovered

from'the spoil run-off outfall (irrespective

of whether it was dead or alive) twenty-two(22) were lost in the spoil mass.

2. 96-hour viability test confirmed that of those

fry that escape into the river via the spoil run­off outlet, 70.6% die during the first 96-hour

period.

3. Over-all mortality rate, including those frythat were lost in the spoil mass, those recov­

ered dead and those passing into the river

alive, was 98.8%.

INTRODUCTION 1

Hydrauli cSuction Dredging Operations in the lower

Fraser River are carried out in connection with projects suchas sand borrow for the purposes of landfill and pre-loading or

for the maintenance of navigation channels. During the down­

stream salmon fry migration period these operations are the

focus of serious concern to fisheries resource managers. Thefry migration usually commences early in March and extends

to the middle of June. When these fry arrive at the lowerportion of the river, they are between three to four centi­metres in length and are generally carried by the river cur­rent. Their small size renders them highly vulnerable to the

suction influence of the dredge pump. Accordingly when they

come within the zone of influence set-up at the cutter head,

they are "drawn into the suction pipe, through the pump anddischarged over the spoil ground.

In 1971, Fishery Officers J. Bentley and V. Knoop of

Mission, B.C., reported observing chum salmon fry in the spoil

pile drain during construction of the south bank approach fill

of the Mission Bridge across the Fraser River. This incidentprompted the Fisheries Service to embark upon a fry monitor­

ing programme in the ensuing years. This was initially

accomplished by periodically screening a portion of the total

outflow from various spoil grounds using IS-inch diametermarquisette dip nets. Monitoring conducted over the years

has proven conclusively that the dredge pumps operating in theFraser River during downstream fry migration period do, in

fact, capture salmon fry and adult eulachon and dischargethem over the spoil ground.

At this

between theoutflow pipe

spoil mass.

stage, the question arose as to the relationship

number of fry observed passing out the spoil pileand the number of fry actually buried in the

It was strongly suspected that these small fragile

2

fry became entrapped in a mixture of clay, silt, sand, gravel

or cobbles and water, pass through a system of- pressure andvelocity changes-, -and are discharged over the large spoil dump

with the result that a significant number of the capturedpopulation would be decimated and buried in the spoil mass

before they could escape into the spoil run-off outlet.

To assess this hypothesis a test was conducted on May

10, 1974 in collaboration with the Department of Public Works,

involving the Hydraulic Suction Dredge DPW 322. A knownquantity of salmon fry was introduced into the suction line

and the fry were recovered after they had passed through thedredge. This involved screening the outflow from the spoil

ground, visual observation and recovery of dead and live fryfrom the spoil ground and the spoil drain. Preparations for

the test, equipment used, test procedures and results are

described in the following pages.

3PREPARATIONS FOR THE TESTS

The test site was located at the easterly tip of the Annacis

Island, while the DPW 322 was located at the Fraser-SurreyDock across the Fraser River as shown in Figure 1.

c ~o l\ T H

"" ~ .It.... - ~.

LOCATIO" OF

DPW 3U .... FRA.ER

SURREY DOCK

,'","

..v++

;;.....-': ,

FIG, 1 LOCATION OF DREDGE & SPOIL GROUND NTS

4

The following is the description of the dredge pump

used in performing the tests:

Dredge Pump - DPW 322

2. Diameter of Suction:

L Pump size: Centrifugal type 62" impeller

24 inches

3. Diameter of Discharge:

4. Power:

5. Cutterhead R.P.M.:

6. Depth:

7. Suction distance fromCutterhead to Pump:

8.* Velocity of fluidwithin pipeline:

9.* Quantity:

20 inches

1550 B.H.P.

Maximum 375

Maximum 45 feet

103 feet

14.3 FPS with 5000 feet pipe­line &30 feet static head

13,500 U.S. gallons perminute at S.G. 1.2 with 5000feet of pipeline at 375 R.P.M.

* Items 8 &9 would be subject to change with alteration

to pipeline length and pump speed.

Photographs of the dredge in operation and a close-up

of the cutterhead are shown in Figures 2 &3.

5

FIGURE 2 DPW 322 in Operation

FIGURE 3 DPW 322 with Cutterhead Raised aboveWater Level

6

Approximately 6,500 chum salmon fry were obtained

from the Qualicum chum salmon spawning channel for the purpose

of the tests. The fry were transported to the site from Vancou­

ver Island in an aerated holding tank mounted on a truck. Uponarrival at the site, two control groups of fry were removedfrom the holding tank. A group of 204 fry were held in a

live box submerged in Fraser River water adjacent to the spoilarea, and 108 fry were held in aerated Qualicum Hatchery water

to determine the initial survival of the experimental fish.Facilities were fabricated to keep and observe the recaptured

fry for a 96-hour viability test. This apparatus consisted of

float-mounted live holding cages which were suspended in theFraser River inside the Phase 2 trifurcation wall as shown in

Figure 4.

FIGURE 4 Float-mounted Live Cages

7

The holding tank containing the remainder of the fry

was acclimatized to the Fraser River water while being trans­ported by barge from the shore to the dredge as shown in

Figure 5.

FIGURE 5 Holding Tank Containing Live Fry Being Trans­ferred to Dredge

Three separate tests were conducted for the purpose

of comparison. A miniature settling pond was created with

perimeter dykes built with previously dredged sand adjacent tothe normal settling pond. The cross-sectional area at the topof the miniature settling pond was 4,800 square- feet and was

capable of containing 110,000 gallons of discharge (approx­

imately 10 minutes of dredge discharge). This mini-site wasequipped with a valve controlled manifold drain from which the

outflow spilled onto a horizontal screen. In this way, thetotal spoil pile overflow discharge was screened. Due to the

small amount of time required to conduct the test on theminiature spoil area (approximately 2 hours) two tests were

conducted at this site. The dredge discharge pipeline was

8

fitted with a wye branch with control valves which allowed the

pump flow to be switched onto either the miniature settling pond

or the main settling pond as desired.

The normal spoil site was much larger than the miniature

spoil site. Total area of the normal spoil site was approxim­

ately 154,600 square feet. From commencement to completion ofthe test of the normal spoil site required in excess of 8 hours.

TEST PROCEDURE

Test No. 1 - Pond

Upon arrival of the holding tank at the dredge, 978 fry

were counted and stored in an oxygenated container prior to

inserting them into the suction line of the dredge; See Fig. 6.

FIGURE 6 Counting Fish

9

The normal operation of the dredge ceased at 1150

hours. It was shut .down temporarily and the valves in the wye

branch were adjusted to switch the spoil discharge from the

main settling pond to the miniature settling pond. The ladderwas raised and 978 chum salmon fry were introduced into the

suction line through a slug valve located about 50 feet back

from the cutterhead. Immediately after this operation, thecuttherhead was lowered and s imul taneously the pump started

running. Unfortunately, river water alone was pumped for 5minutes until the cutterhead hit the bed material and resump­

tion of normal dredging operation had taken place. The total

pumping time for this test was 10 minutes. During that timethe settling pond was filled after which the valve at the wye

branch allowing flow into the miniature settling pond wasturned off. Then the manifold valve located at the spoil

drainage outlet was opened and the reservoir was drained andscreened at a regulated flow as shown in Figure 7.

FIGURE 7 Monitoring Miniature Settling Pond Outflow

10

Fry recovered from the screen were stored in a water­

filled, aerated container and at periodic intervals these

specimens were transferred by boat to the live holding cages

for the 96-hour viability test as shown in Figure 8.

FIGURE 8 Transfer of Retrieved Live Fry to HoldingCages

Upon complete draining of the spoil, the miniature

settling pond was traversed by men on foot and observed mortal­ities were recorded. For the purpose of the test, strandedfish in small pools which had no means of escaping into the

river were considered to be dead. For results of this test,refer to tables I, II &IlIon Pages 14-16.

Test- No. 2 Miniature Settling Pond CDredge Was9peratin~ NormallyJ.

11

For this test 1,192 chum salmon fry were used. The

basic procedure for this test was the same as in Test No. 1

described previously except that the fry were introduced

into the dredge system with the aid of a funnel through a

1-1/2 inch hole directly into the suction pipe as shown in

Figure 9.

FIGURE 9 Inserting Fry into-Suction Pipe on Dredge

This procedure enabled the normal dredging operations

to continue without interruption. The dredge discharge con­

taining approximately 15% solids was pumped for 5 minutes

into the miniature settling pond and then the flow was diver­

ted back to the main settling pond. For results of this

test, refer to tables I, II &IlIon Pages 14-16.

Test No. 3

12

Main Settling Pond (Normal Dredging Operations).

For this test, 3,777 fry were funneled directly into the

suction line as was done in Test No.2 described previously,

while the dredge was in the actual process ~f dredging in theriver bottom to more closely simulate normal operating condi­

tions. The time required to insert the fry was approximately15 seconds.

Monitoring of the main settling pond was continued from

initial fish insertion until the flow had ceased to drainfrom the spoil ground.

structure are shown inThe main settling pond and outlet

Fugures 10 and 11.

FIGURE 10 Main Settling Pond

13

FIGURE 11 Main Settling Pond Outlet Structure

As in the case of the previous tests, the specimen

retrieved alive were tranferred to the holding cages for the

purpose of the 96-hour viability test and were inspected daily

for mortality counts. For results of this test, refer to tables

I, II &IlIon Pages 14-16.

TABLE I

S~~RY OF FRY MORTALITY

Disposal Area Total Solids 15% Length Dis- Duration No, of Fry No. of Fry % of Spill Rate ofSite Volume of Volume charge to of Test Used Recovered way Dis- Recovery

(Approx, ) Spillway x Dead and charge for 100% ofAlive Monitored Discharge

?viani tored

!vIiniature 4800 ft2 ~ fresh- 50 eu yd 130 feet 4:10 hrs 978 291 100~, 1,3,4Spoil Site waterTest #1 110,000 gal

Miniature 4800 ft2 normal mixSpoil Site 55,000 gal 50 eu yd 130 feet 2 :00 hrs 1192 429 IOOe;. 1 :2,8Test #2

Normal 154,600ft2 normal mix 2900 eu yd 630 feet 7:30 hrs 3777 175 80C"c 1 :21. 8Disposal 3,135.000Site galTest #3

* From time of fry entering dredge system, until cessation of monitoring spillwater.

I-'.".

TABLE II

FRY MORTALITY TEST. D.P.W. DREDGE #322, MAY 10, 1974

FRY RECOVERED DURING MONITORING OF SPOIL AREAS

Description No. of Fry No. of Fry % of Fry No. of Fry % of Fry Total No. of Total %of :\0. of Frv I '"; of Fr~Used/Test Recovered Recovered Recovered Recovered Fry Recovery Fry Recovery Recovered I R~coverl

Alive Alive Dead Dead on Spoil ea on ISpoilx

,Ii

Miniature

ISpoil Area- ITest #1 (5 I

I

Imin clear 978 290 29.7% 1 0.1% 291 29.8% 33 3.4::-r Iwater + 5 I,min of norm I

Idredging);

total 10 i Imin , I

Miniature I I,Spoil Area- I ITest #2 419 35. l:c 10

I0.8% 429 35.9% 77 I 6.4S

(under norm1192

I Ipumping cond) I5 min of norm I I

a1 dredging I IMain Spoil I IArea Test #1

3777 160 4.2% 15 0.4% 175 4.6% 3 o. l~(under normpumping con-ditions ....

<.n

*Spoil recovery fry considered independently of drain recovery in order to relate total fry lost in spoil to

total drain recovery.

TABLE III

FRY MORTALITY TEST. MAY 10, 1974

96-HOUR VIABILITY TEST OF CONTROL FRY & FRY RECOVERED FROM SPOIL AREAS

! ,Total # # Live Spe- # of Observa- Observa- 1 %Mortality Cumulative Total Dead UnaCCQunt- c-, Dead of

of Fish cimens put Dead tioD tion @ Each Obser- % :V1orta 1 i ty After 96 ed Losses Total TestDescription Used in to Live in Date Time vat ion Hours After 96

Boxes Box Hours I108 108 0 10/5/74 2030 0.0%

I0.0%

In fa

Control I 0 11/5/74 1400 I 0.0% 0.0% nla

Hatchery 0 12/5/74 1200 I 0.0% I 0.0% nia

o 113/5/74 I 1200

I0.0% 0.0% n -'a

o 14/5/74 1600 0.0% 0.0% 0 0 I nla I204

I204 o i 10/5/74 2030 I 0.0% 0.0% n/a IControl 8 i 11/5/74 1400 I 3.9% 3.9%

In/a

IFraser I 1 I 12/5/74 1200 I 0.5% 4.4% nla,o 113/5/74 1200

I0.0% 4.4~ I n fa

o ,14/5/74 1600 0.0% 4.4% 9 0 n/a

Miniature 978 290 11 110/5/74 2030 I 3.8% 3~8%

ISpoil Area- 8 11/5/74

I1400 2.8% 6.7%

Test 1 ( 5 mil 0 12/5/74 1200 0.0% 6.7%clear water) I 0 13/5/74 1200 0.0% 6.7% I5 min of 2 14/5/74 1600 0.7% 7.2% 22 0 I 72.5~

normal disch IMiniature 1192 419 17 10/5/74 2030 4.0% 4.2%

ISpoil Area 109 11/5/74 1400 26.0% 30.0%Test #2 Unde 0 12/5/74 1200 0.0% 30.0%Normal pump- 3 13/5/74 1200 0.7% 30.7%ing ._condi- 7 14/5/74 1600 1. 7% 32.5% 136 46 76.3';tions.5 minnormal disch

Main Spoil 3777 160 54 10/5/74 2030 33.8% 33.8%

Area Test #1 54 11/5/74 1400 33.8% 67.5% ......2 12/5/74 1200 1.2% 68.8% ~

Under Normal1 13/5/74 1200 0.6% 69.4% I

Pumping Con-2 14/5/74 1600 1.2% 70.6'70 113 25 98.8%

ditions

n/a - Not Applicable

17

DISCUSSION OF RESULTS

As stated earlier, the first two tests were performed for

comparison purposes only. It was felt that the miniature spoil

pile created a cup-like containment in which the water was main­

tained at an artificially high level unlike a normal relativelyflat spoil site with very shallow water depths. The results ob­tained from the third test using the normal settling pond are

considered most valid since the dredge operating conditions viz.the discharge constituents, size, and slope of the spoil ground

relate more closely to a typical dredging operation in the lowerFraser River. Pertinent information from this test is as follows:

1. Out of the total number of salmon fry which wereintroduced into the dredge system only one in every

twenty-two fry emerged at the spillway.

2. Those fry which emerged at the spillway had a

mortality rate of 70.6% during a 96 hour period

after their capture.

3. The accumulated mortality rate was 98.8%. Thisclearly demonstrates that once a fry has entered

the suction intake, its chance of survival is minute.

4. The mortality rate of the control fry which were held inthe Fraser River water was 4.4%.

The 1:22 recovery ratio is .considered a good yardstick for

estimating the extent of damage done to the migrating salmon fry

by the suction dredging operations, however this ratio is subjectto change as the individual dredge operating conditions differ

from the test conditions.

Variables that can influence this 1: 22 relationship are discussed

below:

1. Type of Material Dredged: In the test condition, the

18

material dredged was fairly clean sand. The same area had

been dredged a year earlier. If the dredging is undertaken

in an area which has not been dredged previously, i.e. a

log booming area where the dredge material will contain a

mixture of sand, silt and debris and fibrous material,

more fry will probably be entrapped than shown by the test.

2. Ratio of Water to Solids in the Dredge Discharge: In the

test case, it was reported by Public Works Canada that

the discharge contained 15% solids. It is apparent that

the higher the percentage of solids in the mixture, the

greater will be the chance of fry burial in the spoil mass.

3. Water Quality: Significant variations in the water quality

parameters, viz. temperature, turbidity, dissolved oxygen,

pH, and toxic chemicals (like H2S released during dredging)

have the potential to increase fry mortality and subsequent

burial in the spoil mass.

4. Size, Bed Slope & Efficiency of the Spill Area: The bigger

the spill area, the milder the bed slope, an& the more

efficient the spill area in terms of settling out the solids

of the dredge ate , the greater will be the chances of fry

burial.

5. Pond Planning, Operation &Ma~~~:~~~~:.~he.areawhere

the outflow jet impinges upon the spoil ground often has

to be cleared by bUlldozers to avoid piling up of sand.

The bulldozers can contribute to increased fry mortality

through crushing, abrasion and direct burial.

6. The type &Capacity of a Dredge Pump; Lengths of

the Suction & the Delivery Pipes: The bigger the

capacity of the dredge pump and longer the suction and

delivery pipes the greater will be the chances of fry

receiving abrasions, contusions and lacerations and

eventually becoming entrapped in the soil mass.

19

RECOMMENDAT IONS

In future dredge monitoring operations, efforts should

be continued to design, fabricate, and install screens which

will efficiently sample the entire outflow from the settling pond.

Further in-depth laboratory analysis should be carriedout on the fry that are retrieved from the spoil outflow toascertain the extent of physical damage (both external and

internal) suffered by the fry while passing through the dredgesystem.

It is recommended that all dredging activities in the

Fraser River which are of non-emergency nature be closed duringthe downstream fry migration period considering the accumulated

mortality rate of 98.8% and the ratio of the number of fry re­trieved to the number of fry buried, 1:22.

Emergency maintenance dredging required for navigationchannel improvement should be pre-planned and scheduled in such

a manner that the most predictable trouble spots in the river

bed are dredged outside the March 15 - June 1 closed periodoutlined in the Fraser River Dredging Guide.

20

FRY SURVIVAL AND ANALYSIS

I COLLECTION PROCEDURE PROGRAM

loA floating raft was used to hold "live-boxes"

which contained dredge recovery and "ControlFraser" fry.

these boxes had one side· screened and

allowed a free exchange with the FraserRiver without excessive flow-through

velocities.a totally isolated "bucket" contained

"Control Hatchery" fry - aeration wasprovided by an air pump.

2. Daily during the succeeding 96 hours, alldead fry were counted and preserved in 10%

formalin. At 96 hours all remaining live

fry were similarly counted and preserved

for analysis.

3. The segregation of the control and experimentalfry was as follows:

Control Hatchery - 108 fry were held in aerated

Qualicum Hatchery water to determine initial

survival of stock fish during transport and theexperimental period.

Control Fraser - 204 fry were held in a live

box open to water from the Fraser River to

determine the effect of acclimation and FraserRiver water on survival of stock fish.

Experimental Fish - these fry were held in liveboxes in Fraser River water to determine the

effects of the dredge operation on survival of the

stock fish.

21

II RESULTS OF LABORATORY ANALYSIS OF EXPERIMENTAL

&CONTROL FRY

1. EXTERNAL DAMAGE - fry that were subjected to thedredging procedure generally exhibited some form

of external abrasion and gill siltation (somealso showed gill filament abrasion)

however, this could also be a' result of

handling procedure (though minor as indicatedby control test results).

fry that survived the 96-hour period generally

exhibited little gill siltation which suggeststhat either death (and subsequent settlement

to the bottom) causes the observed gill silta­tion or that significant gill siltation causedmortali ty.

2 . INTERNAL DAMAGEnot determined

detailed laboratory analysis recommended forfuture tests.

III CONCLUSIONS

With the number of parameters that were present in the

test analysis, it is difficult to make precise conclu­

sions about the individual physical and systemic stresseffects of each phase of the dredging operation on these

fry other than the observed mortality of 98.8%.

22

IV RECOMMENDATIONS

In further tests, it is recommended that all possible

parameters be controlled to exclude as much doubt

as possible as to the effect of dredging on thesurvival rate of salmonid fry:

aeration and temperature control in holding tankacclimation period

fry handling controlan improved method of fry recovery should bedeveloped for the spoil sites similar to theminiature-spoil netting rather than the dip-net

technique"

Anonymous. 1949.

BOYD, F. C. 1975.

BRAUN, F. 1974.

23BIBLIOGRAPHY

Hatzic Pump Experiments. Canada

Department of Fisheries and B.C. Game

Commission. p. 19

Fraser River Dredging Guide.

Fisheries &Marine Service. p. 10

Phase II, Monitoring The Effect Of

Hydrau1 ic Suct ion Dredging On Migrat ing

Fish In The Fraser River. Public Works

Canada. p. 9

DUTTA, L. K., &1'. SOOKACHOFF. 1975.

LUCAS, K. C. 1962.

PREMPRIDI, T. 1964.

ROBINSON, J. B.March, 1969.

RYAN, P. 1965.

A Review Of Suction Dredge Monitoring In

The Lower Fraser River 1971 - 1975.

Fisheries &Marine Service.

The Mortality Of Fish Passing Through

Hydraulic Turbines As Related To Cavitation

And Performance Characteristics, Pressure

Change, Negative Pressure &Other Factors.

Canada Department o£ Fisheries; Proceedings

of IAHR Symposium, Japan: Paper No. B-8.

pp. 308-335

Effect of Compressed Air on Mortality of

Fish Passing Through a Model Turbine.

M.A.Sc. Thesis, University of B.C.

Effects of Passing Juvenile King Salmon

(onchorhynchus tshawytscha) Through a

Pump. Anadromous Fisheries: Administrative

Report No. 69-1, State of California,

Department of Fish &Game, Anadromous

Fisheries Branch. p. 13

A device of Injecting Juvenile Fish into

a Pressure Conduit. The Canadian FishCu1turist, No. 34. pp. 27 -29

24

ACKNOWLEDGEMENTS

The authors wish to express their appreciation to the

following persons and organizat'iuns for their assistance:

Public Works Canada for making the Hydraulic Suction Dredge

(DPW 322) and its crew available for conducting the test;

Mr. J.W.C. McNally, Senior Engifteer, Habitat Protection Unit,for making necessary arrangements prior to the test and for

providing over-all supervision during the test period;Mr. M. Flynn, Biologist, Habitat Protection Unit, for his

role in the bio-assay and laboratory analysis of the livefry retrieved from the dredge spoil; Mr. R. Elvidge,

Bio-Technician, Habitat Protection Unit, for his assistanceduring the test, the staff of the Georgia Strait Division

and Qualicum Hatchery for supplying the chum salmon fry and

last but not least, Mr. F. C. Boyd, Chief, Habitat ProtectionUnit, for his perusal of the manuscript and comments.