rP-~D- Hv

~/t)

OPERATING HISTORY OF THE PUNTLEDGE RIVER EICHER SCREEN FACILITY

HUGH SMITH , BC HYDRO

MANAGER, STRATEGIC FISHERIES

POWER SUPPL Y OPERATIONS

th Fl., 6911 

SOUTIIPQINT DRIVE

BURNABY, BRITISH COLUMBIA, V3N 4X8 CANADA

1. 0 Abstract

High turbine mortality levels were identified during the early history of the Puntledge River powerplant. In 1957 a

decision was made to curtail access to headwater habitats and an attempt was made to use fish culture methods to

maintain anadromous stocks. Declining stocks and the need to regain use of headwater habitats, necessitated the

consideration of alternatives for fish passage protection. Several behavioral methodologies were tested including

strobe lights, Fish Scram sound generator and an electric field. Behavioral methodologies resulted in limited

success with bypass efficiencies ranging from 8 % to 11 %. A temporary net barrier resulted in a bypass

effectiveness in excess of 99% for the low discharges tested. Finally, an Eicher penstock screen was installed as

the permanent solution. Test results during a two year experiment showed a bypass efficiency for coho and

chinook salmon smolts in excess of 99% for all expected discharge conditions. Analysis of bypass efficiencies for

st.eelhead, sockeye and chum salmon fry, on an opportunistic basis, provided bypass rates of 100 %, 96 % and 96 %

respectively. Several operational considerations are discussed in the paper.

0 Introduction

The Puntledge River project consists of three structures; a storage dam on Comox Lake, the Puntledge Diversion

Dam situated four kilometers downstream and the powerhouse located a further seven kilometers downstream

towards the mouth of the river (figure 1). Both dams contain fishways for upstream migrant fish allowing passage

to Comox Lake and tributaries. The dams were originally constructed in 1913 by Canadian Colliers Limited to

supply power to local coal mines. Between 1953 and 1958, the British Columbia Power Commission expanded the

facilities and increased the volume of diversion to a new 24 megawatt powerho~.

Anadromous fish stocks in the river consist of st.eelhead, chinook, coho, pink and chum salmon. The construction

of the original project in 1913, detrimentally affected chinook and steelhead stocks which utilized the upper

portion of the watershed. Reconstruction of the facility 

in 1958 resulted in an increased diversion rate from 8.

m3/s to 27.5 m3/s with associated in~s in fish enrainment. The estimated mortality rate through the turbine

was as high as 58% (Department of Fish eries, Canada). Research was carried out at the time on louver deflectors

(Ruggles and Ryan. 1964), however, a decision was made not to utilize the louver design. Instead, the fishways

were closed and fish production facilities were constructed. A spawning channel and hatchery were unable to

maintain target production levels and in 1988 attempts were again initiated to find a mechanism to regain natural

production from headwater habitat.

Several fish guidance methodologies were tested over the period 1989 to 1993. In 1989, a combination of a strobe

light, chain barriers and an underwater hammer were installed at the intake. The strobe light and hammer had

been tested previously at Seton Creek in 1986 with some evidence of behavioral response (patrick and McKinley,

1987). The strobe light had a frequency of approximately one pulse per second and was installed to focus on the

chain array. The hammer consisted of an electrically driven, spring loaded weight in a water tight metal drum

which, when operated created a low frequency high energy sound at a rate of 20 pulses per minute. The use of steel

chains had previously been reported by Brett and Alderdice (1958). For the purpose of this study, steel chains 1.5

meters in length were suspended at 15 em intervals from a boom log floating at a 45 degree angle to the intake.

Results of the test provided a bypass rate of 8.6% with bypass flows of 1.4 m3/s (Bengeyfield and Smith, 1989).
In 1990, a graduated electric field was installed at the intake and fish bypass flows were increased to a maximum

of 5. 7 m3/s. The electric field was created using 25 m long cables arrayed in a 4 m wide plastic mesh envelope.

An electric field was generated around the cables by 600 volt additive phased pulses lasting from 100 to 200

microseconds, in combination with pulse repetition rates of5 to 10 pulses per second. Results form the test

indicated a bypass success of 11. 1 %. The remaining fish, either passed over a second bypass located downstream

of the test site (10.7%), or passed over the spillway during high water periods (63. 1%), with the remaining 20.

passing through the powerhouse (Bengeyfield, 1990).

Following the low success rates of the behavioral and electrical devices, a temporary net barrier was installed and

operated during 1991 and 1992. The 43 m long net was constructed of tarred knotless 210/20 nylon, %" mesh

which was square hung from a floating walkway. The net was cabled to the bottom and sloped downstream to the

surface as well as being angled downstream across the river channel. The net resulted in a bypass rate of99.3% in

1991 and 99% in 1992. In 1991 no fish were impinged on the net or were found to have evidence of scale loss.

Higher discharges in 1992 resulted in an impingement rate of 0.2%. During a peak discharge event in 1992

velocities approaching the screen ranged from 13 to 52 cmls (0.44 to 1.70 f/s). Although the net was found to be

quite effective at the low discharges tested, it was considered to have limited utility during periods of high normal

spring discharges.

In 1992 a team of engineers and biologists were assigned the task of designing, constructing and testing an Eicher

penstock screen. Methods and results of 

screen evaluation and operating considerations since completion of

construction are discussed in this paper.

0 Methods

The penstock screen design patented by George Eicher was selected for installation following a review of options

from designs being utilized throughout the pacific northwest (BC Hydro, 1991). The Eicher concept was

considered to be the most cost effective and efficient application for the facility.

In order to install the screens utilizing previously tested criteria (EPRI, 1993), it was necessary to reduce the

velocity of water in the existing 3.66 m woodstave penstock. This was carried out by removing a section of the

existing woodstave penstock and installing two new sections of steel penstock which joined the woodstave penstock

downstream of the screens (figure 2). Following a period of design and hydraulic testing, two screens were

installed, one in each new section of penstock. A report by Matthews and Taylor (1994) summarizes the design

criteria (table 1) and installation process.

The design of the screen included a temporary evaluation facility to determine bypass efficiency. The evaluation

facility consisted of an energy dissipation chamber, a set of sampling traps, a bypass return to the river, and

evaluation tanks. The traps sampled approximately 15% of water discharged through the screen bypass. In

addition, a sampling device was installed at the outlet of the powerhouse to determine whether fish were able to

pass through the screen seals. During testing, fish were 

released at various locations throughout the screen and the

evaluation facility to further isolate the cause of any scale loss or mortality.

Fish sampled from the evaluation facility were held in tanks for 96 hours, were inspected to assess scale loss and

were then released to the river. A fish was classified as descaled if it was found to have a 16% scale loss on one

side, or a scale loss of 40% on 2 of 5 zones on the same side of the fish. Fish that were not sampled were

transported directly to the river through a 0.

61m pipe. Each year of the test period one of the screen bypass pipes

was diverted to the evaluation facility. The facility was not sufficiently large to accommodate the total bypass of 1.4

m3/s from both screens.

The screens were designed to rotate on an axle by means of hydraulic pistons. Control of the screens, for cleaning

purposes, consisted of two mechanisms; a timing device used to periodically backwash the screens, and transducers

installed upstream and downstream of the screens to sense changes in pressure across the screen. The latter device

was installed in 1994 to avoid negative pressure developing in the woodstave penstock.
, , .

l1'I

a..

a..

l1'I

l1'I

..::t

a..

:)0-

l1'I

a::

l1'I

:I:

l1'I

a::

a::

e,:)

.....I

::I

a..

oc::(

...J
The number of descaled smolts in 1994, was 4.4% of 386 coho, 3.3% of 181 chinook, 12.5% of 64 sockeye and

9% of 26 cutthroat trout sampled. A control sample of 87 coho and chinook captured in the forebay upstream of

the screens was found to be 2.3% descaled (Table 2 and figure 4).

0 Additional Considerations

The decision to install an Eicher penstock screen was made by BC Hydro following consultation with fisheries

management agencies as well as stakeholder representatives. Although no specific criteria were set by which to

judge the success of the screen, it was generally accepted that a successful bypass rate in excess of 80% would be of

benefit to fish stocks and a bypass rate of 95% would be considered highly successfu1. Bypass levels in this range

would allow the opening of fishways to headwater habitat BC Hydro accepted the risk of installing the screen with

the knowledge that inability to meet this expected range in results would necessitate consideration of further

options. Existing agency fish screen criteria were generally not consistent with the design concept of the Eicher

screen.

Total mortality rates for coho and chinook ofIess than 1% was considered to be highly successful and the screen

continues to operate today. In addition to the cost of installing the screen ($4.7 million) there were several

additional considerations with respect to the project. Debris management, maintenance of the screen and the

protection of the woodstave penstock were primary considerations.

1 Debris Management

The Puntledge River originates from several small lakes and tributary streams flowing into Comox Lake. Comox

lake provides storage and acts as a buffer to variations in watershed runoff. A boom located at Comox Dam

captures much of the large woody debris material passing into the lake during high flow events. A two inch

aperture trash rack at the diversion intake structure captures most of the remaining large debris. Small debris, less

than two inches in dimension, enters the penstock.

Inspections determined that certain pieces of smaIl debris such as twigs, grasses and leaves. passed into the

penstock and contacted the screen. Much of this material traveled along the screen and exited through the bypass.

however, some material became lodged in the screen support bars. Lodged material then tended to capture

additional material as it ~oved along the screen. The amount of debris on the screen influences head loss across

the screen as well as fish passage efficiency, particularly for fry which may contact the screen.

A major operational consideration at this site is the integrity of the wood stave penstock. Penstock failure is

avoided, in the event of negative pressure, by closure of the intake gates which results in a system outage. Under

this scenario, discharge from the plant is abmptlyinterrupted. For biological as well as safety and energy reasons,

systems were included in the design to avoid the need to use the safety backup system.

During the test period, the screens were rotated on a four hour cycle and this was generally found to be sufficient in

1993. A pressure sensing control mechanism was installed in 1994 to provide further assurance of protection. The

mechanism was based on pressure transducers located above and below the screen. A pressure differential across

the screen results in automatic screen rotation to sweep debris from the screen surface.

2 Maintenance Reauirements

On two occasions in 1996, the two cleaning mechanisms were unable to manage debris load and the penstock

intake gate closed to protect the penstock and turbine. This resulted in two problems; an immediate reduction in

discharge from the turbine into tailrace area, and; loss of plant energy/capacity from the integrated power system.

Following a system inspection, it was determined that the transducers, which were laboratory quality, were 100

sensitive to debris and dirt and were failing during critical periods. Consideration is being given to replacing the

transducers with field quality units.
Literature Cited

Ruggles, C.P. and P. Ryan. 1964. An investigation oflouvers as a method of guiding juvenile Pacific salmon. Can

Fish Cult. 33:68 P.

Patrick, C.P. and RS McKinley. 1987. Behavioral systems to guide or divert :fish at hydro-electric facilities.

Canadian Electrical Association, Report No. 513 G 543, 45P.

Brett, lR and D.F. Alderdice. 1958. Research at guiding young salmon at two British Columbia field stations.

Fisheries Research Board of Canada Bull. No. 117: 65 P.

Bengeyfield. W. and H.A. Smith. 1989. 1989 evaluation of behavioral devices to divert coho salmon smolts from

the penstock intake at Puntledge Generating Station. Prepared by Global Fisheries Consults Ltd. for BC Hydro.

Bengeyfield. W. 1990. Evaluation ofan electrical field to divert coho salmon smolts from the penstock intake at

Puntledge Generating Station. Report prepared for BC Hydro.

BC Hydro. 1991. Puntledge Diversion Dam permanent fish screen overview study. Hydro-electric Engineering

Division and Environmental Resources. Report No. H2524.

EPRI. 1990. Evaluation of an inclined penstock screen at Elwa Dam - spring 1990 test results. Interim MS report

by Stone and Webster Engineering Corporation and Hosey and Associates Engineering. EPRI, Palo Alto,

California.

Matthews, J. G. and J. W. Taylor. 1994. Design and construction of Eicher penstock fish screens. Canadian Electric

Association. Montreal. Oin~d9

Bengeyfield. W. 1995. Evaluation of the Eicher fish screen at the Puntledge Diversion Dam: year 2 (1994). Report

prepared for BC Hydro.

Bengeyfield. W. 1994. Evaluation of the Eicher fish screen at Puntledge Diversion Dam in 1993. Report prepared

for BC Hydro.

Quamme. D.

, 1993. Summary report regarding the colonization of penstock fish screens by an aquatic invertebrate

at BC Hydro s Puntledge River hydro-electric facility, British Columbia.
Figure 3

Figure 4

Sheet1

Wild smolt and hatchery. chum mortalities in 1993 and 1994

C')

.c 0)

a 0)

 ...

C')

a 0)

c: 0)

:i: ...

..,.

Q) 0)

g ...

Q) ..,.

.c 0)

- 0)

 ...

iii

0..,.

a 0)

c: 0)

:i: ...

...

=--C') Q) 0)

1:5 0)

Q) C')

.c 0)

 

iii

0""

.c 0)

a 0)

 ...

Proportion of smolts descaled in 1993 and 1994

C')

.c 0)

a 0)

 ...

III

0..,.

..,.

a 0) C') =-- C')

III 0) III ..,.

.E 0)

Q) 0) .c 0) .c 0)

.c ... 1:5 0)

g 

- 0)

... ...

iii iii

0..,.

.c 0)

a 0)

C')

0 0)

5: 0)

.c ...

. ).

ImSerieS1 I

ImSerieS1 I