i

16325

!

i

REEXAMINATION OF ALTERNATIVES TO

REDUCE LOSSES OF STRIPED BASS I

AT 11-E CONTRA COSTA AND

PITTSBURG POWER PLANTS

!

!

Submitted by:

I Pacific Gas and Electric Company

77 Beale Street I

San Francisco, California 94106

December 9, 1985

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I TABLE OF CONTENTS

Section Page

SUMMARY ...................................................... !

1,0 INTRODUCTION ............................................. I-I

I I Purpose I I

1"2 ................................................ . Description of Facilities ................................ !-!-

!.3 Current BTA Provisions .................................!

l.t~ Effectiveness of Current Changes ......................... !-7

2.0 IDENTIFICATION OF ALTERNATIVES ..........................2-1

EGen~rl,"" " ~;~l~(~vaua on ...................................... .........~-I2,3 Description of Alternative’s I~)~ ~r~c~r"

By PGancE ............................................ 2-I

2.t~ Modified Vertical Traveling Water Screens ................. 2-~

2.5 Alternatives to Reduce Circulating Water Pump Operation

at Contra Costa !-5 and Pittsburg 1.4 .....................2-19

2.5. ! VSD Motor Controls ..............................2-19

2.5.2 Two-Speed Motors ...............................2-23

2.5.3 Magnetic Couplings Between Existing Motors

and Pumps .................................... 2-27

2,5,t~ Cross-Overs at Contra Costa I-3 and Pittsburg 1.4 ,, 2-28

2.6 Alternatives Applicable to Contra Costa 1-3 House Units .... 2-37

2,7 Hydrogen Cooling Improvements: Contra Costa

Units 6 and 7 ........................................... 2-39

2.8 Resource Management ..................................2-4 !

2.8. ! Dispatch of the Pittsburg and Contra Costa Power

Plant Units Based on the Geographic Distribution of

Striped Bass Susceptible to Entrainment 2.42

.2,8o2 Dispatch of Like Units at Pittsburg and Contra

Costa to Maintain Discharge Temperatures

Below 86oF Whenever Possible .....................

APPENDIX A

Comparison of Economic Evaluations of Alternatives

With Cost Data Provided in the ! 982 Assessment ..............,,, ,- A- !

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LIST OF FIGURES

i

!-! General Config_uration of the Pittsburg Power Plant Units

Cooling Water Systems .................................... I-2

, !-2 General Configuration of the Contra Costa Power Plant

Units ! -5 and Units 6 and 7 Cooling Water Systems ! -3

2-1 Ristroph Modified Traveling Screen with Fish Bucketss a Modified

Spray and Water Systems and a Sluiceway for F’Jsh ................ 2-8 l, 2-2 Cross-Over System to Allow Single Circulating

Pump Operation at Reduced Loads ..............................2-32

i LIST OF" TABLFS

Table Page

!-! Summary of Characteristics -- Pittsburg Power Plant ............. !-~

i

! -2 Summary of Characteristics -- Contra Costa Power Plant ......... I-S

2-1 Alternatives Determined in 1982 to be Potentially Feasible

for Reducing the Losses of Striped Bass ......................... 2-2

i

2-2 Alternatives Eliminated from Detailed Analysis

in the 1985 Reevaluation ......................................2-3

2-3 Alternatives Evaluated in Detail in the 1985 Reevaluation ......... 2-b,

2-~ Economic Evaluation of Modified Screen Designs:

Contra Costa Units I-7 ....................................... 2-15

2-5 Economic Evaluation of Modified Screen Designs:

Pittsburg Units !-6 ........................................... 2-16

I 2-6 Economic Evaluation of VSD Installations

at Contra Costa Units l-S .................................... 2-21

i

2-7 Economic Evaluation of VSD Installations at Pittsburg Units I-~+ ... 2-22

2-8 Economic Evaluation of Two-Speed Motor Installations

at Contra Costa Units I-5 .................................... 2-25

2-9 Economic Evaluation of Two-Speed Motor Installations

at Pittsburg Units I -~ ........................................ 2-26

2-10 Economic Evaluation of Magnetic Couplings Installations

I

at Contra Costa Units !-5 .................................... 2-29

2-1 ! Economic Evaluation of Magnetic Couplings Installations

at P.ittsburg Units ! -~ ........................................ 2-30

2-12 Economic Evaluation of Circulating Water System Cross-Over

| Installation at Contra Costa Units I-3 ......................... 2-34

2-13 Economic Evaluation of Circulating Water System Cross-Over

Installation at Pittsburg Units ~-~ ............................. 2-35

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I SUMMARY

i This report presents results of a reexamination undertaken by Pacific Gas and

Electric Company (PGancE) in  ̄response to discussions with the staffs of the

i

Central Valley and San Francisco Bay Regional Water Quality Control Boards.

The purpose of the reexamination was the evaluation of the current feasibility~

i

costs~ and potential effectiveness of alternative methods and technologies for

further reducing the losses of larval and juvenile striped bass at PGandE’s Contra

Costa and Pittsburg power plants. This report summarizes and documents results

I of the technical evaluation of alternatives as an update and extension of the

"Assessment of Alternatives to Reduce the Losses of Striped Bass~ Contra Costa

I

and P ittsburg Power P iants" (TERA, ! 982).

This reevaluation identified alternatives that may be feasible and could be.

effective in further contributing to the reduction in striped bass losses at the

two power plants. Alternatives include modified traveling water screens~ various

methods to reduce cooling water volumes at Contra Costa Units !-3, Contra

Costa Units b, and S and Pittsburg Units !-~ various methods to reduce cooling

water volumes required when Contra Costa house units are in service~ hydrogen

 ̄ cooling improvements at Contra Costa 6 and 7~ and two resource management

alternatives.

Information on operation performance, reliability, capital and operating costs~

and the estimated effectiveness of the various alternatives in reducing striped

bass losses are discussed. Cost estimat~es have been based in large part on

.9operating conditions at the two power plants i_n ~1_98b, and 198S. The

. effectiveness of each alternative to reduce striped bass losses was based on

I assumed operating conditions and actual cooling water system operations, unit

loading~ and striped bass densities observed in 198b, and 1985. Estimates o~

’i ~ _~ntal ~reduc.tion in striped bas~ losses are based__~_oc:L~ctual and

. ..~e~.d) operation in 198/+ and/or 198S~ .and therefore should be used only as a

I

.

relative guide in evaluating various alternatives because of the diffii~Jlty in

determining if these two years are representative. The actual cbst and

effectiveness of each alternative will vary between years based on future

operating and environmental conditions influencing the losses of striped bass at

the Pittsburg and Contra Costa power plants.

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!.0 INTRODUCTION

PURPOSE

i This investigation was undertaken by Pacific Gas and Electric Company

(PGandE) in response to discussions with the staffs of the Central Valley and San I Francisco Bay Regional Water Quality ControlBoards, to review the current

feasibility, costs, and potential effectiveness of alternative technologies for

further reducing the losses of larval and juvenile striped bass at PGandE’s Contra

Costa and Pittsburg power plants. This report summarizes the results of the

more recent technical review of alternatives in the "Assessment of Alternatives

to Reduce the Losses of Striped Bass, Contra Costa and Pittsburg Power Plants"

i

(TERA, !782) and evaluates additional technologies.

This section of the assessment provides a summary description of the Contra

I Costa and Pittsburg power plants anddescribes the measures implemented to

comply with the BTA requirements of the NPDES permit provisions for the

I

facilities. Section 2.0 provides a .brief description of alternatives now under

more detailed consideration by PGandE to assist in reducing the losses of str~iped

bass at the power plants and reviews the cost of implementation and the

potential effectiveness of the alternatives.

i 1o2 DESCRIPTION OF FACILITIES

I The physical configurations sand major characteristics of the cooling water

systems at the Contra Costa and Pittsburg power plants are shown in Figures !- I ! and !-2, and in Tables I-! and !-2. Extensive descriptions of the designs and

operatio.ns of the facilities are presented in the original assessment document

I

completed in 1982. Copies of that document are available from IpGandE.

I E5"73.3 I - !

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m

Pier

Suisun Baj~

Intake~

irculafing Wafer

pumps Dik~J~a,rge

Transitibn : 0

Discharge structure

Gate %"

: wells 0

0

to r.o~in¢

FIGURE I- I

GENERAL CONFIGURATION OF THE PITTSBURG POWER PLANT

UNITS I-7 COOLING WATER SYSTEMS
i

FIGURE I-2

GENERAL CONFIGURATION OF THE CONTRA COSTA POWER PLANT

UNITS I-5 AND UNITS 6 AND 7 COOLING WATER SYSTEMS
TABLE I - I

SUMMARY OF CHARACTERISTICS

PITTSBURG POWER PLANT

Design Design i

Gross Net Cooling Condenser

’ Unit Unit Unit Water Temperature(a) Output Output Flow Rise

I

(MWe) (MWe) (gpm) (oF)

I 160 i 53 98 ~ 600 I S

2 170 i 63 98,600 I 5

I

3 160 153 98,600 15

Z~ 170 163 98 ~ 600 I 5

I 5 330 325 160,500(c) 18

I

6 330 325 160,500(c) " 18

7 7Z~0 720 20~000 (b)

I

TOTALS 2,060 2,002 735~ZI00

!

(a) At.design power output.

i (b) Unit 7 uses a closed cycle cooling tower system to dissipate heat.

(c) The circulating water pump motors on these units are equipped with VSDs.

I

All other units have constant speed pump motors.

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TABLE !-2

SUMMARY OF CHARACTERISTICS

CONTRA COSTA POWER PLANT

!

Gross Net Design Design

Unit Unit Cooling Condenser

Unit Output Output Water Temperature

Flow Rise (MWe) (MWe) (gpm) (OF)

I 122 116 89,800(a) 16

2, 122 !16 89,800(a) 16

3 122 116 89,800(a) 16

/~ 122 117 55,200

5 ! 20 ! ! S 55,200

6 3b,5 3/~0 152,700(b)

7 3~5 3b,0 152~700(b) 19

I

TOTALS 1,298 ! ,260 685,200

Auxiliary Cooling I! ~800

I ~;97,000

I

(a) Cooling water flows include both the main and auxiliary (house) units.

I

(b) The circulating water pump motors on these units are equipped w~h VSDs.

All other units have constant speed pump motors. -

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I

1.3 CURRENT BTA PROVISIONS

I A number of changes to operations at the Contra Costa and Pittsburg power

plants were required as a condition of the NPDES permits for the facilities

issued in 1983, and were supplemented by certain voluntary measures undertaken

by PGandE to aid in the reduction of striped bass losses at the facilities. The

I

operational changes required as conditions of the NPDES permits and those

undertaken voluntarily by PGandE are listed below.

I. Measures Required in the NPDES Permits

I !. water removed from service Circulating pumps were as

soon as practicable after a unit was removed from service~ in order to reduce cooling water volumes.

I 2. Variable speed circulating water pump controls with discharge temperature feedback were installed at Pitfsburg

Units 5 and 6 and at Contra Costa Units 6 and 7.

3. A resource management plan was implemented to preferentially operate Pittsburg Unit 7 whenever possible during I

the striped bass entrainment period based on the unit’s

availability for commitment and dispatching.

The area in the vicinity of the Pittsburg Power Plant and

Contra Costa Power Plant Units 6 and 7 cooling water

intake structures was dredged to reduce intake approach

i

velocities by modifying the area’s bathymetry.

5. The use of Pittsburg Units I-6 and Contra Costa

Units I-7 was reduced to the extent possible during the I

entrainment period.

~;. An entrainment monitoring program was conducted at

I

both the Pittsburg and Contra Costa power plants

(required beginning in 1985). Results of this program

provided weekly information: on the size-specific densities

I

and normalized (150 mm equivalent) densities of striped

bass entrained. These data provided input for the

preferential dispatching of units between Pittsburg and

Contra Costa in a voluntary effort to further reduce I

actual striped bass losses.

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I

Voluntary Measures Implemented During the 198t~

and/or I~)~b Lntrainment Heriods

!

Io Units at Pittsburg ,and Contra Costa were dispatched to

maintain discharge temperatures below the 86OF (30oc) I

threshold for entrainment thermal mortality whenever

possible during the entrainment period.

I

2. An independent daily inspection and report was made on

the operation of individual circulating water pumps at all

units~ operation of the fish pump return system at Contra

Costa Units i-S~ and discharge temperatures for all units I

throughout the entrainment period to help ensure rigorous

adherence to operat.ional practices designed to .reduce

cooling .water flows/discharge temperatures at the two

power plants.

I 3. Pittsburg and Contra Costa units were preferentially

dispatched based on the geographic distribution of larval

I

and juvenile striped bass.

I

I.b, EFFECTIVENESS OF CURRENT CHANGES

The relative effectiveness of operational changes instituted at the two plants

I during 198b, (March I~ 198b, to February28~ 1985) was estimated using the

SIMBAS Hindcasf model. The relative estimate of striped bass loss reduction

was based on 198t~ striped bass densities and actual cooling water system

operation in 198t4. These were compared with average base operations in 1976~

I

1978~ and 1979. An estimated 63 percent reduction in striped bass losses was

achieved in 198t~ representing a saving of 55~600 equivalent striped bass.

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I

2.0 IDENTIFICATION OF ALTERNATIVES

2. ~ GENERAL

This section provides a brief description of the method of identification and

I

evaluation of alternatives and describes the engineering and environmental

characteristics of those alternatives reexamined by PGancE.

I 2.2 EVALUATION METHOD

I The assessment of alternatives conducted in this study was based on a reevaluation of the alternatives determined to be potentially feasible in the 1982

investigation and additional alternatives that may aid in reducing the losses of

striped bass, The 1982 Assessment of Alternatives completed by PGanclE

I

considered a total of t43 alternatives to reduce losses of striped bass at the

Contra Costa and Pittsburg power plants. Twenty-two of these alternatives

i

were determined to be potentially feasible based on evaluations completed

during the assessment (Table 2-1). The determination was based on two primary

considerations, The first was whether the alte_r_~ative would be effective, in

reducing the losses of larval and juvenile striped bass at either of the power

plants. The second was the compatibi/it o_t_t_~ alternative with the existing

I plants from an engineering and operations perspective. Table 2-2 lists

alternatives which were screened from further analysis in this reevaluation and

I

provides the basis for their exclusion. Table 2-3 lists those previously considered

alternatives which warranted further detailed consideration in this update as

i

well as several new alternatives.

2.3 DESCRIPTION OF ALTERNATIVES NOW UNDER CONSIDERATION

I BY PGondE

As shown in Table 2-3, the reevaluation of alternatives to reduce the:~ses of I

striped bass at the Contra Costa and Pittsburg power plan’ts identified~, 4)possi~

hie alternatives that may be feasible and could be effective in further~contriI buting to the reduction in losses of ~triped bass at the power plants. The

! E5-73.3 2-!

048540

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TABLE 2-I

ALTERNATIVES DETERMINED IN 1982 TO BE POTENTIALLY

FEASIBLE FOR REDUCING THE LOSSES OF STRIPED BASS

CONTRA COSTA AND PITTSBURG POWER PLANTS*

I

Shoreline Intake Structure at Contra Costa I-S

Offshore Intake for Contra Costa !-5 I Addition of Porous Dike in Front of Intake Structures

Modify Cross Sectional Area of Intake Systems

Provide Lateral Escapeways at Contra Costa I-5

I Angled Traveling Water Screens at Contra Costa !-5

Maintenance Dredging

I

Bar Rack Maintenance

Removal of Predatory Fish at Contra Costa I-S

Modify Existing Traveling Water Screens I

Addition of Physical Barriers

Cylindrical Wedge Wire Screens

Fish Pump Removal Systems

I Mechanical Draft Cooling Towers

Reductions to Circulating Water Pump Operations

I

o Selective Operation of Pumps

- Install Two-Speed Motors

- Install Variable Speed Motor Controls

- Install Magnetic Couplings

I Alternative Cooling Water Sources

Reduce Thermal Stresses on Entrained Striped Bass

I

Reduce Recirculotion Using Physical Barriers at Contra Costa 6 and 7

Resource Management

Operation of Selected Units

I

- Dispatch Units to Operate with Discharge Temperature of 86oF or Less

Whenever Possible.

- Dispatch Units Based on Location of Striped Bass

!

i

* Source: Assessment of Alternatives to Reduce the Losses of Striped Bass~

C0ntra Costa and Pittsbur9 Power Plants (TERA~ 1982).

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 ̄

I

TA3LE 2-2

ALTERNATIVES ELIMINATED FROM DETAILED

I

ANALYSIS IN THE 1985 REEVALUATION

ALTERNATIVE BASIS FOR EXCLUSION FROM DETAILED ANALYSIS

! Addition of Porous Dike The operational reliability of a porous dike intake structure

in the Delta environment is uncertain. No new information is

I

available to suggest that sedimentation and debris loading

would not result in unacceptable operational reliability of

porous dike intake structures at the two plants.

Modify Cross Sectional Area of Intake Systems . It was concluded in the 1982 assessment that these alterna- I

Shoreline Intake Structure at ContraCosta I-S fives would not significantly reduce losses of striped bass.

Offshore Intake for Contra Costa I-S No new biological information is available to suggest that

Angled Traveling Water Screens at Contra Costa I-5 these alternatives would contribute to. a significant reduction

in striped bass impingement losses. The number of striped I

bass currently being impinged at Contra Costa I-S is very

low (approximately 10fish per day). These alternatives

would not reduce entrainment losses substantially.

I

Provide Lateral Escopeways at Contra Costa I-S It was concluded in the 1982 assessment that lateral escapeways would not significantly reduce entrainment or impingement losses. No new information is available to suggest that

striped bass losses would be reduced substantially by this

alternative.

I Maintenance Dredging This alternative was implemented in 1983.

Bar Rack Maintenance This alternative was implemented in 1983. I Removal of Predatory Fish at Contra Costa I-5 No new informationis availableto suggest that this

rive would contribute to a significant reduction in striped

bass losses. Predatory fish, including striped bass and catfish, were removed from the Contra Costa I-S intake struc- I

ture in 1983 when the intake was dewatered for maintenance

and repair. Observations made in the Contra Costa I-S

intake forebay over the past two years suggest that predation

losses are not significant at the present time. ! Addition of Physical Barriers As discussed in the 1982 assessment report, designs for this

- Cylindrical Wedge Wire Screens type of system hove not been tested for power plant cooling

water systems as large as those of Contra Costa or Pittsburg.

I

No additional data is available on the operations or reliability

of wedge wire screens at power plants with cooling water

flows and environmental conditions similar to those at

Pittsburg or Contra Costa.

I

Fish Pump Removal Systems A fish pump removal system is in operation at Contra Costa

I-S but was determined in the 1982 assessment to be ineffective at Pittsburg as well as the remaining units at Contro

Costa. No new information is available to suggest that fish I

pumps would be effective in reducing striped bass losses at

the shoreline intake structures for either the Pittsburg Power

Plant or Contra Costa Units G and 7.

i

Mechanical Draft Cooling Towers Based on information presented in the 1982 assessment, it

was concluded that the cost of mechanical draft cooling

towers was disproportionate to the expected reduction in

striped bass losses. No new information is available to

suggest that the cost of mechanical draft cooling towers I

would be substantially less than that estimated in the 1982

ossessment. ’-

Alternative Cooling Water Sources The only potentially feasible alternative source of cooling

I

water identified in the 1982 assessment for the Contra Costa

and Plttsburg power plants would be unavailable until after

199Z~. No additional information is available to suggest that

alternative water sources would be potentially available

I

earlier than predicted in the 1982 assessment.

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TABLE 2-3

ALTERNATIVES EVALUATED IN DETAIL IN THE 1985 REEVALUATION

ALTERNATIVE COMMENTS

Modify Existing Traveling Water Screens See Section 2./~

Reduce Circulating Water Pump Operatian See Section 2.5

Contra Costa !-5 and Pittsburg !~

2 - VSD motor controls See Section 2.S.I

~

- Two-speed motors See Section 2.S.2

~f - Magnetic couplings See Section 2.S.3

S - Cross overs at Contra Costa I-3 See Section 2.S.~

(~ - Cross overs at Pittsburg 14 See Section 2.S.S

Contra Costa I-3 house units only

-~ - Combined VSDs and two-speed motors See Section 2.6

( - House unit supply from Units 6 and 7

q - New pump(s) for house units

i0 - Modification to existing supply conduits

\( - Recirculation water flow

Contra Costa Units 6 and 7 only

/~- - Hydrogen cooling improvements See Section 2.7

IResa~rce Management See Section 2.8

- Dispatch units based on location of striped bass See Section 2.8. I

_ Dispatch units to operate with discharge .:_

temperatures of 86 degrees F or less when possible. See Section 2.8.2

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following sections provide summary descriptions of the engineering and economic

characteristics of each alternative and discuss the potential effectiveness of

each alternative in reducing striped bass losses.

The effectiveness of the various alternatives in reducing striped bass losses was

estimated using biol_ogical and operational data from 198b, and 1985 which

reflects the resource management program and other operational c.hanges

utilized during the entrainment periods of these two years to reduce striped-bass

losses. The method used in 198b, and 1985 to determine the entrainment start

date and end date relied on a threshold density of 9-10mm striped bass entrained

at the Pittsburg Power Plant and the on use of CDFG summer tow net survey

data each year (as specified in the NPDES permits)s respectively. Considering

the recent changes in the geographic distribution and relative densities of striped

bass susceptible to entrainment, a more sensitive approach to determining when

striped bass are entrained at the two plants each year is appropriate. Results of

the entrainment monitoring studies required at both plants provide the data

necessary to establish the entrainment period start and end dates based on a

density threshold of striped bass actually entrained at both power plants as

discussed in Section 2.8.

The incremental reduction in striped bass losses estimated for each alternative

should be considered as only a relative tool in evaluating alternatives, since the

actual effectiveness of each alternative would vary in future y_.~g~s__ with

variation in both operational and biological factors affecting striped bass losses.

The incremental percentaqe reduction in striped bass losses achieved by various

alternatives in this assessment, primarily operational alternatives such as

dispatch of units based on the geographic distribution of striped bass and

maintaining discharge temperatures below 86oF when possible, would vary in the

future years depending on operations, the spatial distribution of larval and

juvenile striped bass, and the timing and duration of the entrainment period.

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2.b, MODIFIED VERTICAL TRAVELING WATER SCREENS

Modifications to the existing traveling water screens (TWS) and fish handling

I

systems may be feasible at the Pittsburg and Contra Costa power plants. These

modifications could include use of such features as finer mesh screens, fish

I

buckets, increased screen rotation frequency, dual sprays, and gravity sluiceway

fish return systems. While these devices have the potential to be effective

..  ̄ means for reducing either entrainment or impingement impacts, their use must

| include consideration of a balance between biological performance and reliable

operation of the intake system. It would not be prudent to install such devices

I

for these intake systems without first testing both the physical and biological

effectiveness of such devices. Field studies were conducted at the Pittsburq.

I

Plant in 1983 to evaluate both the operational and biological effectiveness

of modified intake screens. Because of the low number of striped bass collected

I

in the study, .results from the impingement survival study were inconclusive. The

extremely low numbers of striped bass collected at the Pittsburg Power Plant

i

during 198t, t and 1985 would not have provided sufficient numbers of striped bass

to support another attempt to quantitatively study the biological effectiveness

of the modified screen.

The discussion which follows presents the conceptual design and environmental

I

assessment associated with implementing modified vertical traveling screens, on

a full-scale basis, on each of the existing intake structures at the Pittsburg and

:

I

Contra Costa power plants.

i

Conceptual Design

This alternative involves the use of modified vertical traveling screens as a

I possible means of reducing impingement and entrainment losses of the Pittsburg

and Contra Costa power plants. This retrofit program could involve modifying

I

the existing vertical traveling screens such that they would have fi~-e mesh

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E5-73.3 24

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C--048545

C-048545
I

screens, fish buckets along the base of each screen panel, a low-pressure spray to

wash the fish from the screen, high-pressure sprays for debris removal, continI

uous screen rotation, and a gravity sluiceway to return the fish to the river.

i

Design Configuration

The modifications which could be made to each vertical traveling water sbreen

I include the following:

I o Replace existing baskets with free-style fish-handling

baskets fitted with fish troughs along trailing edge (Figure

I o Replace existing screens with fine-mesh woven wire

screens (e.g. I/8" x I/2" mesh)

I o Install roller bearings on head shaft

o Install stoody bushing on foot shaft

I

o Replace basket chains

I

o Change high-pressure (95 psig) upper spray to low-pressure (!0-15 psig) back spray of same flow rate

I

o Modify splash housing to accommodate fish return sluiceway.

I Facility Requirements

I

No modifications to the concrete structure would be necessary for the intake at

Contro Costa I-5. A single fish sluiceway could be built to run the length of the

intake structure of Pittsburg I-6. This sluiceway would collect fish from all 13

I screens and carry them to the west end of the intake structure of Pittsburg 5 and

I

.:_

I E5-73.3 2-7

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I

I

I

;_

FIGURE 2-I

RISTROPH MODIFIED TRAVELING SCREEN WITH FISH BUCKETS,

MODIFIED SPRAY AND WATER SYSTEM, AND A SLUICEWAY FOR FISH

(COURTESY OF ENVIREX)

E5-73.3 2-8

C--048547

0-048547
6. Similarlys a sluiceway could be built to run the length of the intake headworks

at Contra Costa 6 and 7. It would collect fish from the six screens and carry

them to the east end of the structure. The sluiceways would be limited to an

average slope of approximately 0.? percent except at the discharges which would

angle steeply downward to lower the fish quickly into the river. The main wash

water distribution header would have to be relocated if the fish, sluiceway is to

be located adjacent to the existing debris trough on the back side of the screens.

Possible alternative locations are the curb of the service road or on the deck in

front of the screens.

From the fish sluiceway located on the intake structures the fish would enter a

sluiceway conduit which would ultimately carry them back to the river. The pipe

for Pittsburg I-6 would be approximately 22 in. in diameters and the pipes for

Contra Costa I-S and 6 and 7 would be about 16 in. in diameters both made of

fiberglass.

To ensure flow velocities greater than the sustained cruise speed of the fishs a

slope greater than 0.S percent would be required. Howevers if subsequent

analyses show that it is desirable to keep the flow subcritical (where deep flow

becomes a thins high velocity film) in order to preclude shock impacts, the slope

would be maintained at less than I percent. Assuming the need for subcritical

flow~ an average slope of 0.7 percent was used as the design point.

in the design concepts the fish return conduit would run 300 ft along the shore.

The conduit would be maintained at a 0.7 percent grade, to ensure deep rapid

flow, until near the point where the fish would be released where the conduit

would slant downward at a z~S degree angle to lower the fish rapidly into the

water. Finailys the conduit would discharge to the river at least 20 ft offshore.

Performance

I Because of the uncertainties associated with the operation and.’.-biological

effectiveness of modified intake screens installed at the Pittsburg rind Contra

I

Costa power plants, PGandE installed and tested a fine-mesh Ristroph modified

traveling water screen at the intake structure of Pittsburg Power Plant

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E5-73.3 2-?

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C--048548

C-048548
Units !-~. The tests were conducted between November 1982 and January 198b,.

The principal objectives of these tests were to:

o Determine if the modified screen is operationally acceptable

o Determine if the modified screen would significantly

reduce striped bass losses.

Operational Tests

The operational performance of the modified screen was evaluated using the

following three criteria:

!. The modified screen must be capable of passing sufficient

water flow to the circulating water pumps under various

seasonal Suisun Bay water conditions

2. The amount of carryover or leakage of debris into the

circulating water system must not impair plant availability or reliability

3o The maintenance requirements of the modified screen

must not impair plant availability or reliability.

In order to characterize the environmental and operational conditions under

which the modified screen was being tested, the following data were collected:

sediment levels behind Units !-7 intake screens; a series of measurements to

index the bathymetric contours in front .of the intake structures; drive motor

operations on the modified screen; differential hydraulic gradients across the

modified screen; and tide elevations at the plant.

in conjunction with this supplementary data, the water velocities were continuously measured behind seven traveling water screens serving Units !~. This

included the modified screen to determine if the fine-mesh screen can pass

sufficient water flow to the circulating water pumps (criterion !)o Thi~was done

between November 1982 and November 1983. Based on a comparison of these

velocity measurements, the conclusion was reached that the fine-mesh modified

E5-73.3 2- I 0

C--048549

(3-048549
I

screen can pass sufficient water to the circu.latin.q water_pumps to maintain unit

operation. Qperation of the modified screen was acceptable durln~ Ih~ te~t

J From November 1982 to January 198/~, visual inspections of the modified screen

baskets were made periodically and documented to determine if the amount of

i carryover or leakage of debris associated with the modified screen would impair

plant availability or reliabilit.y (criterion 2). Also, a log was kept noting the

i

frequency of cleaning and volume of debris removed from each condenser water

box inlet, in summary, the modified screen appeared to satisfactorily exclude..

most of the typical debris....(e.g., peat) from the circulating water system~

I however, the__~zaj~wash system of the modified screen c~d not adequately___

remove filamentous algae that became entwined in the modified screen and

~ubsequentlycarried over into the circulating water system where it then fouled

the condenser water box inlet and had to be removed manually. Based on

I

observations by PGandE personnel, carryover of this algae has not been a

problem on the conventional screens in the past or during the test period. The

likelihood of the algae recurring in abundance in the vicinity of Pittsburg and

Contra Costa power plants in future years is unknown. Therefore, no conclusion

can be made as to whether or not this would be a chronic operational

i, maintenance problem for the modified screen. Another concern is the ability of

the modified screen to exclude the large (heavy) amounts of debris from the

I

cooling water system which have been a problem in previous with the years

conventional screens. During this test, large quantities of debris did not come

i

into contact with the modified screen. Therefore, no conclusion was made on

’ how well the modified screen would perform in excluding large amounts of debris

from the circulating water system. Results of the testing program were

I

inconclusive regarding criterion 2.

From November 1982 to January 198b,, maintenance records were kept for work

performed on the modified screen as well as on the adjacent conventional

I

screens to determine if maintenance requirements of the modified screbn would

impair plant availability or reliability (criterion 3). The~modified scre_e.o_bo~L~

~_rnore rnaintenance ’requirements than the_ e-onventional screens~ however, PGandE

E5-73.3 2-II

/

c’o4855o

C-048550
!

staff considered the increased maintenance level acceptable. Although PGandE

I. followed routine maintenance requirements for the modified screen and these

~

requirements did not impair plant availability or reliability~ there were tw.__~__o

i

~outa.qes of the modified screen~ attributable to failure of screen components

during the test period. Both outages were related to continuous operation of the

cmodified screen. The first outage was due to a worn motor bearing which

occurred 13 weeks after beginning continuous operation. The second outage,

which occurred after i/~ months of operation, was due to failure of the basket

chains. During the examination of the screen~ PGandE personnel observed that

the basket chain had fractured in two locations and that some of the baskets had

become bent. in additions excessive wear of the basket end plates, the drive

sprockets~ and the boot plate was noted. This indicated that the modified screen

failure may have been due to the basket chain stretching. The mechanical

" failure of the screen was evaluated~ however~ additional information on screen

m~___aintenance requirement~ needs to be ec~Lb~re a conclusion can b_______~e

drawn regarding the impact of increased s_creen maintenance (routine preventive

maintenance~ screen overhaul~ and repair frequency following mechanical failI ure).0.n p!ant ~~sz_

Biological Tests

The biological evaluation of the modified screen tested at the Pittsburg Power

Plant was developed within the framework provided by the striped bass simulotion model (SIMBAS). This model has established a basis for estimating

incremental benefits for reducing striped bass losses associated with installation

of modified intake screens at the Pittsburg and Contra Costa power plants.

However~ several basic assumptions included in SIMBAS have been founded on a

synthesis of data compiled primarily from laboratory studies on size-specific

screen retention, low-pressure spraywash efficiency~ and impingement survival

of larval and juvenile striped bass. The Pittsburg field study was developed to

provide quantitative information about impingement of striped bass on the

modified screen for use in evaluating the screen’s biological effectiveness.

i’ E5-73.3 2-12

I

C--048551

C-048551
The biological field studies were conducted from June to September 1~83. These

studies were intended to provide data useful in determining: (!) the efficiency of

the low-pressure spraywash system in removing different size classes of striped

bass from the test screenl (2) the specific size classes of striped bass retained on

the small-mesh screen~ and (3) the proportion of striped bass in each size class

surviving impingement on the modified intake screen. A total of 217 impingement samples were collected in 35 days of sampling which resulted in the

collection of only 287 striped bass (only 61 of 217 samples contained striped

bass). Beca=use so few striped bass were collected during the test period~ the

results of the bioloqical field studies are statistically inconclusive.

Available data indicate that the low-pressure spraywash system was effective

(greater than 80 percent removal efficiency) in removing impinged striped bass

greater than 30 mm long from the modified screen~ but substantially less

effective for smaller striped bass. However~ no definite conclusions could be

drawn because of the small number of striped bass collected in the impingement

samples. Size-specific screen retention could not be quantified with confidence

by normalizing densities to 150 mm equivalent bass because a statistically

insignificant number of striped bass were collected in the impingement samples.

General trends in the length frequency distributions .of striped bass collected~

however~ suggest that retention of striped bass less than 20 mm in length is low

and that most striped bass greater than approximately 25 mm long appear to be

retained by the modified screen. An insufficient number of striped bass were

collected to statistically characterize the 96-hour impingement survival.

General trends in impingement survival observed for the juvenile striped bass

collected in this study were~ however~ considerably lower than those expected

based on laboratory findings.

A biological evaluation of modified vertical traveling screens conducted at the

Danskammer Point Generating Station (Hudson River~ New -York) provided

results similar to results of the impingement survival study conducted on the

modified screen at the Pittsburg Power Plant. Intake.screen modilfications

tested in the Danskammer impingement survival study consisted of fish buckets

on the screen panel% a neoprene splash plate~ and low-pressure spraywash

header. This study directly compared impingement survival rates at the

E5-73.3 2-! 3

I

C’048552

C-048552
!

modified screen with those at a standard vertical traveling intake screen during

I

continuous and intermittent wash modes. White perch were the most common

species collected during the tests. Long-term (8b,-hour) impingement survival

was found to be significantly lower on the modified screen than on the

conventional screen during continuous operation for young-of-the-year white

perch impinged during the fall and for yearlings and adults impinged during the

I spring. Survival of yearlings (only 5t~ collected) during the winter was not

significantly different between the modified and conventional screens. The

study concluded that "under the conditions observed the Danskammer at plant,

there seems to be no particular advantage in using the modified screen system"

l

(A Biological Evaluation of Modified Vertical Traveling Screens. Prepared for

Central Hudson Gas and Electric Corporation by Ecological Analysts, lnco 1982o).

! Field studies conducted at the Pittsburg Power Plant and the studies at the

E)anskammer plant both suggest that modified intake screen~ ar~ not effec’~iv~ in -

consistently improving survival of impinqed striped bass and white perch.

!

The extremely low numbers of striped boss collected in impingement monitoring

I

studies during 1984 and 1985 to date at the Pittsburg Power Plant would not have

provided sufficient numbers of striped bass to support a quantitative study (with

statistically significant results) of the biological effectiveness of the modified

screen.

I Costs

i : The estimated capital costs and economic evaluation for modified screen designs

at the Contra Costa and Pittsburg power plants are shown in Tables 2J~ and 2-5.

I

I

E5-73o3 2-I ~

i

 ’048553

C-048553
Capital ~ (1983 (E)lla~) 127,7~ 127,7~ 127,7~ 127,~ ~7,~ ~,~ ~,~ 1,4~,~

~ ~ (1~ ~11~) 1~,~ 1B,~ 1E~2~ 1~ 1E~ 32~ 32,~ 116,~

~ ~1 pl~ ~ ~~ 137~ 137,~ 137,~ 137,~ 137,~ 433,~ 433,~ 1,555,5~

~ ~1~ pl~ ~ ~ ~11~) 1~365 1~,365 1~,365 1~,365 1~,365 ~,7~ ~,7~ 1,741,227

~~ 23,155 23.155 23,155 23,155 23,155 72,7~5 72,~5

~ D~ ~ 177,5~ 177,52~ 177,5~ 177,5~ 177,5~ 557,~ 557,~ 2,~2,411

~I~I I~ 52,67g 52,67g 52,67~ 52,67~ 52,67~ 165, ~2 165, ~2 5~,115

~ ~ 37,7~5 37,7~ 37,785 37,7~5 37,7~ 118,393 118, ~3 425,311

~ ~ ~7,~5 ~7,~5 ~7,~5 ~7,~5 ~7,~5

~I ~ (@ 15 ~ 11fe) ~,231 ~,231 ~,231 ~,231 ~,231 176,~ 176,~ 6~,2~

~ ~1 ~ @ 1B ~ 11~e ~,634 1~,634 I~,634 1~,6~ ~,6~ 311,~ 311,~ 1,125~

~ ~ ~ @ 15 ~ llfe ~,311 ~,311 ~,311 ~,311 ~,311 272,714 272,714 ~,~

~I ~ ~ @ ~ ~ l~fe 82,927 ~,927 82,927 82,927 82,927 ~5,~ ~5,~ 9~,245

1~:ff~S: (a) ~ calculation~ by ~ 9--3~--85 b~secl cn clara ~m the 1982 stuck.
im

COSt (1982 dollars) 22~,75~ 22g,75~ 228,75~ 2~,7~ 411,~ 411,~ 1,~,~

~ (1~2 ~11~s) 17,7~ 17,7~ 17,7~ 17,75~ 33,~ 33,~ 137,~

~i~l pl~ ~ (1~ ~ll~m) ~,~ 238,~ 238,~ 2~,~ ~,~ ~,~ 1,~3,~

~i~1 pl~ ~ (1~5 ~11a~) 2~,977 2~,977 ~,977 2~,977 497,573 497,573 2,~3,B~

~ ~,~7 ~,~7 ~,~7 ~,~7 74,636 74,6~ ~,4~

D~ ~ 3~,~23 ~7,~23 3~7,~23 3~7,~23 572,2~ 572,2~ 2,372,512

1~ ~,23~ 85,23~ 85,23B 85,23~ 1~,~5 158,~5

~ ~ ~,369 ~,369 ~,369 ~,369 119,~ 119,9~ 497,~

~ 4~,622 456,622 456,622 456,622 ~1,~21 ~1,~21 3,5~,529

~ (~ 1~ ~ life) 116,8~ 116,8~ 116,8~ 116,8~ 217,776 217,7~ ~2,~1

~ (@ 15 ~ life) %,~5 95,~5 95,~5 %,~5 1~,629 178,629 7~,6~

~ (~ ~ ~ life) ~,~7 ~,~? ~,~7 ~,~7 161,524 161~524 669,715

~~ 5,~ 5,~ 5,~ 5,~ 16,~ 16,~ 55,~

~ ~~ ~ter S~ 475 475 475 475 7,~8 7,258

~1 ~ ~ 1B ~ 11~ 1~,925 1~,9~ 1~,925 1~,925 3~,676 ~,6~ 1,~,~51

~ ~ ~ 15 ~ 11~ 143,9~ 143,9~ 143,9~ 143,9~ 325,529 325,529 1,2~,7~

~1 ~ @ ~ ~ life 1~,742 . 1~,742 134,742 134,742 3~,424 3~,424 1,155,815

~O1~;: (a) (~st calculations by Y~A 9-3~85 based cn data £rcm the 1g132 study.
Effects On Striped Bass

The potential reduction in striped bass losses attributable to installation of

modified traveling screens at the Pittsburg and Contra Costa power plants was

estimated using results from the hindcast version of the striped bass simulation

model (SIMBAS). Assumptions regarding size-specific impingement survival used

I

in the analyses were those based primarily on laboratory studies (referred to as

literature-based impingement survival results, where survival varies from 0.62 to

0.75). Biological data collected in the modified screen test conducted at the

Pittsburg Power Plant in 1983 suggest that actual survival of striped bass

i

impinged on modified ~creens is substantially lower than imp~nqement survival

rates derived from laboratory studies_(where survival varies from 0 to 0.$9).

Incremental percentage reduction estimates were also calculated using results of

the 1983 impingement study. The 198b,_.__~striped bass density distribution and plant

operation data were used in the analysis.._..Oper_ationnl ~_~nditlo~__for 1976 19L~78,

I

and 1979 were ~he basis for comparison.

The incremental percentage reduction in relative striped bass losses associated

with installation of modified intake screens is shown below:

!

Incremental Percentage Reduction

i

Contra Costa

Contra 6 and 7, and I

Costa Pittsburg Pittsburg

I-5 I-~, 7 5 and 6

Impingement Survival Results Based On Literature

Modified screens with 3/8 in. mesh 0.3 0.6 1.3

Modified screens with fine screen mesh -3.8* 1.0 0.5

(1/8 x I/2 in.)

1983 Pittsbur9 Impingement Survival Results

Modified screens with 3/8 in. mesh 0. I 0.2 0.3

Modified screens with fine screen mesh -3.8* -i l.b, ,-16.5"

( I/8 x 1/2 in.)

* Increase in losses.

E5-73.3 2-17

C--048556

(3-048556
A reduction in losses on a fine-mesh screen compared with losses on a

conventional 3/8 in. mesh screen would occur if the impingement survival rate of

those fish retained on the fine-mesh screen but not on the 3/8 in. mesh screen is

higher than the entrainment survival rate. in years when the intake water

temperatures and plant operation are greater, the entrainment survival rate

would be less.

During 198b, (March I./98/~ to February 28, 1985) an estimated 32,650 equivalent

striped bass were ~ at the Pittsburg and Contra Costa power plants

combined. |t was estimated that modified screens installed at the t~.o p~ants

wou~d have reduced (increased) the number of equivalent striped bass ~ in

198/~ as shown below:

Reduction in Equivalent Striped

Bass ~in 1984

Contra Costa

Contra 6 and 7, and

Costa Pittsburg Pittsburg

I-S I-b,, 7 S and 6

Impingement Survival Results Based On Literature

Modified screens with 3/8 in. mesh 250 550 I IS0

Modified screens with fine screen mesh -3/~00" 900 /~00

(1/8 x 1/2 in.)

1983 Pittsbur9 Impingement Survival Results

Modified screens with 3/8 in. mesh 100 150 300

Modified screens with fine screen mesh -3/~00" - ! 0000 - !/~550"

(I/8 x 1/2 in.)

* Increase in losses,

Because of uncertainties regarding their potential effectiveness in reducing

striped bass losses, it was concluded that modified intake screens with 3/8 in.

ee~cF.~3_z~h cr f~.ncr ~esh are not a demonstrated technolo<jy for-use at the

~nd Confra Costa power plants~_L.~.

i E5-73.3 2-18

I

C--048557

C-048557
2.5 ALTERNATIVES TO REDUCE CIRCULATING WATER PUMP 

OPERATION AT CONTRA COSTA I-5 AND PITTSBURG I-4

I

The 1982 assessment completed by PGandE identified four major alternatives

I

available for reducing the operation (and thus the cooling water flows) of the

circulating water pumps at both the Contra Costa and Pittsburg power plants.

I

These alternatives included new equipment or modifications to the pumps serving

the main units at each plant and consisted of I) VSD motor controls; 2) twospeed motors; 3) magnetic couplings; and 4) cross-over systems to permit single

pump operation at certain units. Each of these four alternatives has been

reevaluated in this assessment for those units at the plants which do not now

I

employ VSDs. In addition to these alternatives, PGandE has identified options

for reducing cooling water flows associated with operation of Contra Costa

house units.

I

2.5. I VSD MOTOR CONTROLS

The installation of new motors with variable speed (frequency) controls on the

I circulating water pumps at the Pittsburg 1-4 and Contra Costa I-5 units would

allow flexibility in matching circulating water flow rates to unit load.

!

Conceptual Design

! Variable speed controls modify the frequency of the electricity used to run

motors and thereby allow normal single-speed motors to operate at variable

speeds. At present the only variable frequency controls available for loads below

800 hp operate at 480 volts. These controls could be installed at Pittsburg 14 to

I control the existing circulating water pump motors, which currently run off t~80-

volt busses. Because the motors for the Contra Costa units draw current from

I ~I60-V busses, stepdown transformers would be required. The controls would

require construction of air conditioned motor control buildings, step-down

I

transformers for the new motors and condenser air evacuation pumps.

I E5-73.3 2- ! ?

I

C--048558

C-048558
!

Based on monitoring and operating data acquired since installation of VSD units

I

at Contra Costa 6 and 7 and Pittsburg S and 6~ VSD installations at the smaller

units of the plants could reduce total annual circulatin_g_ water volumes by

I

approximately b,0 percent.

I

Costs

The estimated costs and economic evaluations for installation and 0perationof I variable speed pump controls at Contra Costa Units I-S and Pittsburg Units !-6

are shown in Tables 2-6 and 2-7.

! ~ffec~s On Striped Bass

I

The potential incrementa~l reduction in striped bass losses at Pittsburg Units I-~

i

and Contra Costa Units I-S was estimated u_~ssing the forecast version of the

striped bass simulation model (SIMBAS)o The forecast version uses estimates of

intake temperature and plant load to estimate discharge temperatures and

i cooling water volumes. While this approach makes it difficult to accurately

reproduce actual 1986 discharge temperatures and flow conditions~ it does allow

I

for consideration of variations in cooling water flow where VSD operation

depends on load and temperature. The 1986 striped bass density distribution and

I

plant operation data was used in the analysis~ .and operational conditions for

1976, 1978~ and 1979 were used as the basis for comparison. During the period

from March 1~ 1984 to February 28~ 198S an estimate.d 32~6S0 equivalent striped

I bass (from a hindcast model simulation) were ~at th~.).~ plants. The

estimated reduction in the number of equivalent striped bass ~ in 1986 and

I the corresponding incremental percentage reductions in losses associated with

the simulated operations of variable speed pump control are shown below=

Contra Contra

Costa Costa Pittsburg I !-3 6 and 5 ~-/~

Estimated reduction in equivalent

i

striped bass ~in 1986 600 350 !,750

Estimated incremental percentage reduction 0.7 0°6 !o9

I

E5-73.3 2-20

!

C--048559

C-048559


2.5.2 TWO-SPEED MOTORS

The installation of two-speed motors on the circulating water pumps at the

Pittsburg l-b, and Contra Costa l-S units would allow some flexibility in

matching circulating water flow rates to unit load.

I Conceptual Design

I

This alternativ% without the retrofitting described for the cross-over system in

Section 2,5.~s would require new two-speed motor% an upgraded motor control

I

center, and condenser air evacuation pumps.

Performance !

This system would limit the choice of circulating water flow rates. Contra I Costa !-5 could be operated with circulating water flow rates equal to

approximately SO, 7S~ and 100 percent of those which currently occur when two

I

circulating water pumps are operated per unit. It would also be possible to

operate Pittsburg IJ¢ at rates equal to approximately S0~ 75~ and 100 percent of

I

the present rates of flow through these units. A S0 percent flow rate would be

achieved by operation of the two circulating water pumps af a unit at the lower

of the two pump speeds. Operation of the two circulating water pumps at a unit

I

in the higher of the two pump speeds would result in a cooling water flow of

100 percent of that which currently occurs. A 75 percent cooling water flow I rate by operating one circulating water pump of would be achieved the lower

speed and one pump at the higher speed. The actual achievable flow rates would

I

be dependent upon the speed ratio selected for the motors~ which in turn would

depend upon the system head characteristics. ’

I

Although installation of two-speed motors would allow some flexibility in

i

matching circulating water flow rates to unit load, t~_wo-speed motor~

~ than variable spe~.ed pump controls (._..__.Section 2.2:!). "-

I E5-73.3 2-23

!

C--048562

C-048562
I

Costs

I The estimated costs and economic evaluations for the installation and operation

of two-speed motors at Contra Costa Units I-S ~nd Pittsburg Units !-0, are

I

shown in Tables 2-8 and 2-9.

I Effects On Striped Bass

I

The effectiveness of two-speed motors in reducing striped bass losses at Contra

Costa !-5 and Pitfsburg !-4 was estimated based on the assumption that the

I

pumps would operate at 50 percent flow when unit load was at or below 50

percent. Circulating water flow was assumed to be 7S percent of design at unit

i

loads from S I to 75 percent and that cooling water flows would be 100 percent of

design when unit load was above 7S percent. Pump operation was assigned to the

lowest level possible within eight-hour or longer time periods based on an

I inspection of hourly unit load records. The eight-hour time period assumed in

this analysis was based on an operational constraint in which motor speed would

I

be changed no more than once in eight hours. After determining the cooling

water flows for each time period for each unit, normalized striped bass losses

I

were calculated using 1980, biological monitoring data. The incremental striped

bass loss reduction was then calculated for each unit using the estimated

i

equivalent loss based on actual operations in

During the period from March I,/980, to February 28, 198S an estimated 32,6S0

I equivalent striped bass were ~ at the two,plants. The estimated reduction

in the number of equivalent striped bass e~h~-in 1980, and the incremental

I

percentage reductions in losses resulting from the simulated operation of twospeed motors are shown below:

I Contra Contra

Costa Costa Pittsburg I

!-3 0, and 5 [-0,

Estimated reduction in equivalent

striped bass ~n 1980, 600 300 1,650

I Estimated incremental percentage reduction 0.7 0.3 !.8

I E5-73.3 2-20,

I

C--048563

(3-048563
T~LE 2.8 co

~T 1 ~T 2 ~T 3 ~T 4 ~T 5

~ ~ (~) @ 1B ~ ll~e (1~,471) (1~,471) (13e,471) ( 81,471) ( 81,471) (5M,357)

~ ~v~s (~t) ~ ~ ~ life ( 82,571) ( 82,571) ( ~,571) ( 13,571} ( 13,571) (274,~)

Corresponding estimates of the effectiveness of two-speed motors in reducing

striped bass losses based on the operations and striped bass densities observed

during the period between March I and September I ~ 1785 are presented below:

Contra Contra

Costa Costa Pittsburg

I-3 /~ .and 5 I-~,

Estimoted reduction in equivolent / 50 300 650

striped bass ~in 1985

Estimated incr~r~tal percentage reduction !o2 0.8 !.8

I

Although the overall incremental percentage reduction in losses was similar in

198/t (2.8 percent reduction) and 1985 (3.8 percent reduction)s the distribution

I

between unit groups varied for the two years. Variation in the incremental

reduction attributable to two-speed motors (and other alternatives) is expected

to vary between years in response to variations in operations and in the striped

I bass density distribution at the two power plants.

I 2.5.3 MAGNETIC COUPLINGS BETWEEN EXISTING MOTORS AND PUMPS

The installation of magnetic couplings between existing motors and pumps at

Pittsburg 14 and Contra Costa I-5 would allow flexibility in matching circulating water flow rates to unit load.

Conceptual Design

Magnetic couplings could be installed between the existing circulating water

pumps and motors to allow circulating water flow rates to be varied continuously

to match unit power levels. The controls needed to operate the couplings would

require new motor control center buildings and a new ! IS-or 220-volt system.

I

Performance

.~

i

The reduction in circulatin._~g water flows with this alternative would be ~

able to those expected for VSDs and could amount to an annual average

reduction of approximately ~t0 percent below the values associated with constant

!

E5-73.3 2-27

!

C--048566

(3-048566
I

speed pump operations. However~ reliability and performance of the existing

I

cooling water pumps with magnetic couplings is uncertain. There is a potential

for excessive pump and mounting vibration because of the extended pump shaft

that would be needed for these installations..Because of concern ,over reliability I and operational problems resulting from excessive motor shaft vibration, it was

concluded that magnetic couplings.do not represe.nf an acceptable

I

reducing striped bass losses at the Pittsburg and Contra Costa power plant_s..

I

Costs

The estimated costs and economic evaluations for the installation of magnetic

I couplings between the circulating water pumps and motors for Contra Costa I-S

andPittsburg 1-4 are shown in Tables 2-10 and 2-1 !.

!

Effects On Striped Bass

! ~nstallation of magnetic couplings between the circulating water pumps and

I

motors would allow flexibility in matching circulating water flow rates to unit

load. The response time and operational flexibility of magnetic couplings for

matching cooling water volumes to unit load is expected to be the same as that

I achieved by variable speed pump controls. However, b~ecause magnetic couplings

are no_ t~considered to be an operationally acceptable alternative~ the effective~

I ness,_____of magnetic couplings in reducinq striped bass losses at Pittsburg 1-4 and

Contra Costa I-S was not quantified.

! 2.5.b, CROSS-OVERS AT CONTRA COSTA 1-3 AND PITTSBURG

I

CONTRA COSTA !-3

I A cross-over system of piping and valves permits single circulating wafer pump

operation when unit loads are low. Operation of a cross-over system is feasible I at Contra Costa Units I-3. Contra Costa Units ~ and S havedouble-pass

condensers which result in a higher AT (Table 1-2) than that for single-pass

I

condensers. A cross-over system was concluded to be an impractical approach

I E5-73.3 2-28

C--048567

C-048567
tOl~;~ (a) ~ cslc-ulati~r~ and ~,~p~Ic:ns by ~ ~2~5.

(b) ~ ~ 1~11~ fl~ ~ ra~ ofz 25.5% ~r ~ life, ~.9% ~r 15~ life,

~ 18.~ ~ ~ life.

(c) ~ ~ l~liz~ ~t~ ~ ~ ofz ~.~ ~ I~ life, ~.~3~ ~ 15-~ li~,

~ ~.~7~ for ~ llfe.
(b) Bs~d cn leveli~Wl fixed charge rafts of, 25.59l for l~-lm~r ll~e, 2~.99l f~r’ 15-ysar life.

~ 18.~ f~ ~ llfe.

(c) ~m I~ ~tm~~~: ~.~e~ ~ 1~ li~, ~.~]~ ~I~
!

for reducing striped bass losses at Contra Costa Units 4 and S primarily because

I

of operational constraints associated with the double pass condenser design at

these units.

I Conceptual Design

I The piping and valves now installed on the cooling water systems at Units I-3 of

the Contra Costa Power Plant would allow cross-over operations with some

i modifications to the condensers. As configured, it is possible to each now supply

condenser with one circulating water pump at reduced loads but additional

I

equipment would be required to maintain circulating water pressures within

acceptable limits. This alternative would thus require the installation of vacuum

I

priming systems and motor controls. Allowance was also made for replacing

circulating water pump motors and switch gear.

I PITTSBURG I J-lWith the existing circulating water systems for Pittsburg I J% two circulating

water pumps must be operated for each unit to assure proper flow distribution

through the condensers whenever the units are operating. A cross-over system

of pipes and valves with condenser evacuation pumps (vacuum priming systems)

would allow these units to be operated with one circulating water pump when

under partial loads.

Conceptual Design

The major design and operating features of a single-unit cross-oversystem are

presented in Figure 2-2 (a total of four cross-over systems would be required to

retrofit Pittsburg I-4). Replacing circulating water pump motors and switch

gear may also be required for this alternative at both Pittsburg and Contra Costa

units. During normal full load operations the cross-over butterfly valv~ would

be closeds all circulating pump discharge butterfly valves would be ope%’and all

circulating water pumps would be operating. Whenever a unit was operated at

less than about half load for at least 6 hours during the night or on weekends~ one

pump would be shut downs the associated discharge valve would be closed~ and

E5-73.3 2-3 !

C--048570

C-048570
/

FIGURE 2-2

CROSS-OVER SYSTEM TO ALLOW

SINGLE CIRCULATING PUMP OPERATION

AT REDUCED LOADS
the cross-over valve would be opened. The circulating water pump still in

operation would therefore supply water to both halves of the condenser. When

going from two-pump to one-pump operation~ a complicated dynamic change in

pressures will occur within the circulating water system of the unit. When the

cross-over valve reaches the fully opened position~ the flow rate from the

remaining pump would increase (runout) until a new lower circulating water

system pressure head is established. The reduction in pressure head which would

occur at this time could result in air accumulating in the condenser-water boxes.

If this air were not removed~ a restriction of flow through the upper condenser

tube rows would results reducing condenser effective cooling surface and baking

dirt onto the condenser tube surfaces. To avoid this phenomenon~ the condensers

of each unit retrofitted with a cross-over system would have an air evacuation

system.

Costs

The estimated costs and economic evaluations for the installation and operation

of cross-over systems at Contra Costa Units 1-3 and P ittsburg Units !-6 are

shown in Tables 2-12 end 2-13. Cost summaries presented in Tables 2-12

and 2-13 include cross-over systems which utilize the existing circulating water

pump motors at Piffsburg I-6 and Contra Costa I-3. Cost estimates are also

presented which include the installation of new circulating water pump motors at

each unit because of concern over the reliability of the existing motors.

Effects OnStriped Bass

The potential effectiveness of cross-over systems in reducing striped bass losses

at Pittsburg 1-~ and Contra Costa !-3 was estimated based on an assumption

that the cross-over system would be operated whenever a unit was operated at or ~.,~

below 50 percent load for 6 hours or longer at night (defined as 2100 to 0600

hours) and on weekends. Hourly unit loads for 1986 and 198S were reviewed for

each unit and the number of consecutive hours of operation at or below S0

percent load during each specified time period were compiled. For those periods

when operation remained at or below 50 percent Ioad~ it was assumed that

operation of the cross-over system would result in a reduction in cooling water

E5-73.3 2-33

C--048572

C-048572
i

CD~T~ CCNTRA COSTA

~IT 1 i~IT 2 %~IT 3 ~OTAIS

i

~ D~ ~ 67,~ 67,~ 67,~ ~2,~

~i~ ~~ ~,~27 ~,~7 ~,~7 ~,~82

~ ~ ~ 14,337 14,337 14,~7 ~,~i

~i ~ ~i,~ ~I,~ ~i,~ ~5,593

~

~ ~ (@ ~ ~ ~e) ~,~7 ~,~7 ~,~7 ~,~i

~ ~ ~ ~t (@ 15 ~ ~fe) 21,3~ ~,381 21,381 ~,1~

~ ~ (@ ~ ~ ~fe) 19,3~ 19,3~ 19,3~ ~,~i

~

~ of ~t ~ ~~ (c) 31,332 31,332 31,332 93,~

~i~ ~ ~s (d) 15,~ 15,~ 15,~

~t ~ ~ 8,~ 8,~ 8,~ ~,~

~ ~ ~s (~t) @ I~ ~ l~e ( 19,~i) ( 19,~i) ( 19,~1) ( 57,~3)

~ ~s (~t) @ ~ ~ ~fe ( 12,~) ( 12,2~) ( ~,~) ( ~,~3)

~: (a) ~ ~~ ~~ m ~si~ ~ M ~2~5.

r

(d) ~ ~ ~s ~ ~ 1~ ~s/~ ~ ~ 1-3.

I

ff5-73. 2-3 

C--048573

C-048573
2-13

~ 1-4 (a)
flows of 50 percent. The corresponding reduction in equivalent striped bass

losses was estimated for each time period for each unit,

During the period from Marc,h ~ J98k to February 28, 1985 an estimated 32,650

equivalent striped bass were ~at the two plants. The estimated reduction

in the number of equivalent striped bass ~-~:~ppemin 198/~ and the incremental

percentage reductions in losses resulting from the simulated operation of crossovers are shown below:

Contra Costa Pittsburg

Estimated reduction in equivalent

striped bass ~ in 198t¢ 350 950

Estimated incremental percentage reduction 0.4 1.0

Corresponding estimates of the effectiveness of cross-over systems in reducing

striped bass losses based on the operations and striped bass densities observed

during the period between March 1 and September I, 198S are presented below:

Contra Costa Pittsburg

! -3 I

Estimated reduction in equivalent

striped bass cropped in 198S 3S0 SO0

Estimated incremental percentage reduction 1.0 !.3

The relative effectiveness of cross-over systems in reducing striped bass losses

was estimated to be greater in 1~85 than in 198/~. The difference in estimated

incremental percentage reductions between the two years is due in large part to

greater relative reductions in striped bass losses at Contra Costa 1-3 in 1985.

The increase in incremental percentage reduction estimates for Contra

Costa !-3 between 1984 (0.4percent) and 1985 (l.0percent) resulted from

differences in both unit operations and the density distribution of striped bass

susceptible to entrainment between the two years used in this analysis.

E5-73.3 2-36

i

C--048575

C-048575
,!

2.6 ALTERNATIVES APPLICABLE TO CONTRA COSTA !-3 HOUSE UNITS

i The Contra Costa Power Plant employs three house units that are used to

Provide transmission system stabilitys spinning reserves and start-up capability

i

for Contra Costa !-3 during a system outage, These house units are currently

supplied individually with cooling water from a main circulating water pump.

Two circulating water pumps for a main unit operate when both the main

generator unit and house unit are in service. Howevers only one circulating

water p_~mp need be_~_.gj;ze~s~en only the house unit is in service.

/ The three house units at Contra Costa are each ? MW electric generating units.

House unit operation varies between single units two units and three unit

i

operations although two units are in service most frequently. Given the mode of

operation of the units of Contra Costas there are periods fhr0ughout the year

where only one house unit is in operation and is supplied by one operating

I circulating water pump. A review of pump operations data for 1985 showed that

.operation of a house unit alone~_occurred approximately !2 percent of t..h.e time.

I

in view of this operational feature and the existing installation% an alternative

means of supplying the house units at Contra Costa may be available.

I

Five alternatives were evaluated for reducing cooling water volumes associated

i

with Contra Costa hodse unit operation. Alternatives included a combination of

variable speed pump drives and two-speed motor% supplying house unit cooling

water from Contra Costa Units 6 and 7s installation of new pumps dedicated to

I providing house unit cooling waters modifications to the existing house unit

supply conduits, and an operational option of recirculating water flow within the

i

Units !-3 cooling water system, Each of these alternatives was evaluated based

on operational feasibility and cost of implementation, All of the alternatives

I

considered are equally effective in reducing cooling water volume required for

operation of the house units. After the alternatives had been evaluated,

i

.recirculatin__tio.g_wnter fJ_o_~ within the Contra Costa !-3 cooling water system was

".

selected as the preferred option.__

!

I E5-73.3 2-37

C--048576

C-048576
Recirculating cooling water is currently possible with the existing piping

configuration of the house unit cooling water supply system~ and would involve

the use of existing condenser bypass piping to recirculate that portion of the

cooling water volume withdrawn by the circulating water pumps not required by

the house unit for unit operation. Indeed, this operational procedure can be used

during periods of house unit operation only.

As described in Table I-2, the circulating wafer pumps for Units !-3 of the

Contra Costa plant are design’~d for a cooling water flow rate of/~,900 gpm per

pump and can only be operated at this flow rate with the existing constant speed

pumps. Since the cooling water flow requirem_____ent of one house vnit is

approximately _9,000 gpm,_.___a substantial excess volume of cooling water would be

pumped and discharged during periods of house unit operation only, without the

bypass piping. Through the realignment of valves and controls during house unit

operation only, it is possible to ~hat .nnrtinn nf the design flow not

~r..e.quired by ..the house unit and to return this recirculation flow to the pump

intake of the circulating water system for Units !-3. Thus the total volume of

cooling water withdrawn from the river during this mode is only 9,000 gpm (for

one house unit)~ resulting in o significant reduction in the volume of cooling

water used by Contra Costa Units i-3.

I

Cost "

i

Because the c~.rculating water system at Contra Costa I-3 currently has the

necessary.piping and control valves to permit recirculation flow during house

i

unit operation, ~ siqnificant capital expenditures are expected for this alternative. Incremental costs associated with operation and maintenance of the

recirculation system and initiation of a data reCording procedure to document

I the frequencyand duration of recirculation floware anticipated to be minimal.

Effects On Striped Bass .:_

I

Inspection of 1985 operating records indicated that specific house units were in

operation approximately 12 percent of the time when the corresponding main

I

E5-73.3 2-38

1

C--048577

C-048577
unit was not in service. No records are available~ however~ on either the

frequency or duration of water recirculation. The mortality of entrained striped

bass during periods of recirculation flow is also unknown. Mortality of entrained

striped bass attributable to mechanical stresses during repeated passage through

the house unit cooling system when recirculation flow occurs may be as high as

100 percent~ although this is offset by a reduction in the number of new fish

entrained.

The potential effectiveness of recirculating cooling water flow in support of

house unit operation was estimated based on the assumption that recirculation

would occur when a specific house unit was in operation more than 2/+ hours after

the corresponding main unit was removed from service. Operating records were

reviewed to compile information on the frequency and duration of house unit

operation. Based on these operating records it was assumed that .cooling water

volumes could be reduced to 9~000 gpm when house unit operation exceeds main

unit operation by more than 2/+ hours. Mortality of striped bass entrained during

periods of recirculation was assumed to be 20 percent. Using unit-specific

equivalent striped bass losses for 198/+ as a basis~ it was estimated that recirculationW~ I le_~°’fI~ ,co~ling water flow would have reduced the number of equivalent

striped bass ~in 198/+ by less than 250 fish~ an incremental reduction of

0.3 percent. Recirculation flow af Contra Costa I-3 during house unit only

operation was estimated to reduce the equivalent numberof striped bass crcppc~

between March I and September I~ 1985 by approximately 150 fish~ an incremental percentage reduction of 0./+ percent.

2.7 HYDROGEN COOLING IMPROVEMENTS:

CONTRA COSTA UNITS 6 AND 7

Currently the Contra Costa Units 6 and 7 are occassionally curtailed due to high

hydrogen gas temperatures. The combined curtailments for Contra Costa Units

6 and 7 due to high cold gas temperature have averaged/+200 MWh/yr between

1978 and 198/+. PGandE is currently evaluating the alternative ap~ooches for

i E5-73.3 2-39

C--048578

C-048578
I

hydrogen cooling improvements at Contra Costa Units 6 and 7. Resolving the

hydrogen temperature problem will provide some benefits in reducing the losses

I of striped bass at the Contra Costa Power Plant by reducing the need for

committing additional generating units.

!

i

Effects On Striped Bass

I

The incremental reduction in striped bass losses resulting from hydrogen cooling

improvements on Contra Costa Units 6 and 7 was estimated by assuming the

i

,,elimination of curtailments at Units 6 and 7 and thereby reducing the

c,~ommitment of other units at the Contra Costa Power Plant. Hourly unit

curtailment and unit-specific operating records were examined to determine the

I occurrence~ frequency~ and duration of Contra Costa Units 6 and 7 curtailments

and operating conditions when commitment of other units at the Contra Costa

I Power Plant might have occurred in anticipation of potential unit curtailments.

It was assumed that under such conditions~ operation of one unit at Contra Costa

I

Units !-5 could have been eliminated.

I

Based on the levels of operation assumeds it was estimated that an incremental

reduction in striped bass losses of ~p~_~_roximately 0.7 percent could be achieved

by eliminatin~g the__.hydrogen tem~p_e_r,_a_tu_r~e_p_roblem. During 198b,~ it is estimated

I

t-hat the number of equivalent striped bass~ would have been reduced by

6S0 fish. Based on levels of operation and the striped bass density distribution I observed between March S~p,terr~er I and it estimated that the 1985, was

number of equivalent striped bass ~ would have been reduced by approxiI

mately 500 fish~ an incremental percentage reduction in 1985 of I.!t percent.

I

The effectiveness of hydrogen cooling improvements at Contra Costa Units 6

and 7 will vary in future years in response to factors such as electrical demand~

the operational characteristics of the hydrogen cooling systems intake water

I E5-73.3 240

C--048579

C-048579
temperatures, and the densities of striped bass susceptible to entrainment and

impingement. No costs are associated with this alternative as PGandE will need

to resolve the hydrogen temperature problem for its own purposes.

2.8 RESOURCE MANAGEMENT

I

Consideration of resource management alternatives focused on two options:

I

o Dispatch of units at the Pittsburg and Contra Costa power

plants based on the geographic distribution of striped bass

susceptible to entrainment.

I o Dispatch of like units at Pittsburg and Contra Costa

power plants to maintain discharge temperatures below

86° F whenever possible.

Estimates of the incremental reduction in striped bass losses associated with the

I

resource management alternatives discussed below will depending on the vary

timing and duration of the entrainment period. The effectiveness of the

I

resource management alternatives in reducing striped bass losses was estimated

using biological and operational data from 198b, and 198S which reflect the

i

resource management program and other operational changes utilized to reduce

striped bass losses during the entrainment periods of these two years. The

approach used to determine the entrainment start date relied on a threshold

I density of 9-10mm striped bass entrained at the Pittsburg Power Plant. The

entrainment period end date was established using CDFG summer tow net survey

I

data each (as specified in the NPDES permits). Considering the recent year

changes observed in the geographic distributional patterns and relative densities

I

of striped bass susceptible to entrainment~ among other factors~ a more sensitive

approach to determining when striped bass are entrained at the two plants each

I

~" Results of the entrainment monitoring studies required at

both plants provide the data necessary to establish the entrainment period start

and end dates based on actual occurrence of striped bass in all size classes

I entrained at both power plants.

I E5-73.3 2-~ 1

C 048580

C-048580
!

Inspection of normalized striped boss density distributions for 1978, 1979, 198b,,

I and 1985 for each plant has led to the development of_a proposal in which a

normalized striped bass density threshold_of S x 10-4 eauivalent bass/m3 woul_~_d

be used____~to initiate and end the entrainment period. Based on the density of bass

collected, the resource management program would be in effect whenever the

density of entrained striped bass at either power plant exceeded S x 10-4

equivalents/m3o Information provided to PGandE Power Control on the

I densities are highest during ?he entrainment period.

..

2.8.1 DISPATCH OF THE PITTSBURG AND CONTRA COSTA POWER

PLANT UNITS BASED ON THE GEOGRAPHIC DISTRIBUTION OF

STRIPED BASS SUSCEPTIBLE TO ENTRAINMENT

This alternative is based on the dispatch of units at the two power plants in

accordance with the geographic distribution of larval and juvenile striped bass.

If, for example, the relative density of striped bass susceptible to entrainment is

higher at the Pittsburg Power Plant than Contra Costa, then favoring the

dispatch of Contra Costa units could result in fewer striped bass being entrained.

Conceptual Approach

The approach to this alternative would be to dispatch unHs, to the extent

feasible given other operating constraints, as indicated by economic dispatching

unless contradicted by the geographical distribution of striped bass (with the

exception of preferential operation of Pittsburg Unit 7). Using data collected

from the entrainment monitoring program, actual entrainment densities are

available" weekly for use in establishing dispatching priorities. Entrainment

samples are collected from the discharge of Pittsburg Units 5 or 6 and Contra

Costa Units 6 or 7 weekly during the striped bass entrainment period (sampling is

scheduled for the period from May ! to August I). Based on the size~, pecific

density of striped bass collected in each sample, o normalized density (number of

equivalent bass/m3) is calculated for eachpower plant and reported to PGandE’s

I

E5-73.3 2-42

I

C--048581

C-048581
I Power Control Department on a weekly basis as one input to scheduling unit

i

dispatch at both plants during the following week.

Performance

!

Entrainment sampling data (normalized densities) were used as one input in unit

I

dispatch at Pittsburg and Contra Costa during the entrainment period in 1984

and 1985. Comparative entrainment samples were collected on. Monday. and

I

Tuesday at the two power plants, the samples were processed, and larval and

juvenile striped bass were identified and measured each week. Normalized

densities from the Monday and Tuesday samples were documented, and results

I for both power plants were reported to PGandE Power Control by Friday. These

weekly density comparisons were used in establishing unit dispatching priorities

I for the following week.

I Costs

I

The cost of this alternative is associated with the differential cost of preferential operation of Pittsburg Unit 7 and the dispatch of other units at the two

power plants in a mode other than that dictated by economic dispatching

I criteria. The estimation of incremental cos).ass~ociated with dispatch of units

~based on the geographic distribution of striped bass is ~_nm.nl~x nD~d has not been i estimated for use in this report.. The overall estimated cost for differential fuel

use associated with the resource management plan during the 1984 entrainment

I

period was $4.6 million. The cost of the current entrainment monitoring and

reporting effort as a determinant of the geographic distribution of larval and

I

juvenile striped bass is approximately $100,000 per year based on the current

weekly turnaround of monitoring data.

!

i

I E5-73.3 2-43

I

C--048582

C-048582
Effects On Striped Bass

I

The incremental reduction in striped bass losses attributable to use of the

I

geographic distribution in striped bass entrainment at the two plants was

estimated using operating and biological data collected in 198z~ and 1985.

Because PGandE voluntarily implemented a scenario of dispatching units at the

I Pittsburg and Contra Costa plants based on the striped bass density difference

between the two locations in 198/~ and 1985~ the actual operating data reflect

I the contribution of this alternative within limits imposed by other operating

constraints. Several methods were used to evaluate the potential effectiveness

I

of this alternative. In general~ the analyses involved altering the plant-specific

striped bass density for each entrainment collection to reflect a geographic

distribution which was completely opposite to the actual distributions observed

in 198b, and 1985. Using this approachs the assumed incremental reduction in

striped bass losses in 1985 was estimated to be f¢ percent~ representing a

I reduction in 1985 equivalent striped bass losses of I~t~00 fish. No incremental

reduction was detected in striped bass losses for 198zt. The effectiveness of unit

I dispatch based the distribution of entrained is on geographic striped bass

expected to vary considerably between years in response to variation in the

I

distribution of striped bass and variation in operational flexibility between units

at the two plants.

I

2.8.2 DISPATCH OF LIKEUNITS AT PITTSBURG AND CONTRA COSTA

TO MAINTAIN DISCHARGE TEMPERATURES

BELOW 86OF WHENEVER POSSIBLE

. The mortality of larval and juvenile striped bass entrained at the Pittsburg and .! Contra Costa power plants is dependent on exposure to both mechanical and

thermal stresses. Results of entrainment survlval studies conducted at both

I power plants show that entrainment mortality is less than 20 percent when

discharge temperatures are less than 86OF. Entrainment mortality increases

I

. significantly when discharge temperatures exceed 86OF and entrainment mortality is 100 percent at temperatures of 93.2OF and above. Becduse of the

I

sensitivity of entrained striped bass to discharge temperatures above 8~oF~ one

alternative for potentially reducing striped bass losses involves minimizing the

i

occurrence of discharge temperatures above 8~°F during the entrainment period.

E5-73.3 2-44

!

C--048583

(3-048583
I

Conceptual Approach

I This alternative would consist of dispatching like units to all reach 86oF

discharge temperatures before any unit exceeds 86oF. The power levels at which

any unit is able to operate without exceeding 0 discharge temperature of

would depend on the temperature of the intake water and the condition of

I

numerous unit components.

I

Performance

PGandE implemented a program during the 1984 and 198S entrainment periods to

I dispatch like units to maintain discharge temperatures below 86OF when

practical. Inspection of the hourly discharge temperature records for the period

I

from May 1985 showed that exceeded 86oF throughJuly, discharge temperatures

less than IS percent of the time:

I

I Percent of Hourly

Temperatures

I Above

Contra Costa 1-5

I

Contra Costa 6 13

Contra Costa 7 I 0

Pittsburg I-~ 7

i

Pittsburg S I

 ̄ Pittsburg 6 I I

I Cost

I

The cost of this alternative, although not calculated for this report, would

include differential fuel use costs for dispatching less efficient units to maintain

i

discharge" temperatures below 86°F whenever possible.

Effects On Striped Bass

The effectiveness of maintaining discharge temperatures below 86o F whenever

I

possible was evaluated by reviewing unit-specific curtailment records for the

I E5-73.3 2J~5

C--048584

C-048584
198b, entrainment period. The curtailment records designate, by day and

occurrence, the duration of curtailments for each unit attributable to maintaining discharge temperatures below 86o F. Since the actual hourly unit-specific

operating records for 1984 (and 198S) reflect voluntary like unit dispatch to

minimize discharge temperatures above B6oF, it was necessary to estimate what

striped bass losses might have been in the absence of such dispatch. The analysis

assumed that discharge temperatures would have been ?1o F on average (based

on an analysis of actual discharge temperatures), resulting in entrainment

mortality, of 80 percent during that time period when a curtailment occurred.

Operation of variable speed pumps was assumed to be 100 percent for the entire

duration of each curtailment. Based on this assumed operating scenario and the

corresponding striped bass density data for 198b,, a potential striped bass

entrainment loss was calculated. The difference between the potential loss and

the actual loss, summed over the 198b, entrainment period for all units, was

assumed to reflect the incremental reduction in striped bass losses resulting

from maintaining discharge .temperatures below 86° F when possible. Based on

these assumptions, the incremental reduction in striped bass losses was

esfi~m~ated to be 5 percent, representing a reduction in equivalent striped bass

losses during 198b, of approximately ~,600 fish. The estimated incremental

reduction in striped bass losses during the period from March ! to September !,

198S was also estimated to be approximate.ly ~i percent, representing a reduction

in the number of equivalent striped bass~of approximately 1,800 fish.

.:_

I E5-73.3 2-46

C--048585

C-048585
I

APPENDIX A

I

COMPARISON OF ECONOMIC EVALUATIONS OF ALTERNATIVES

i

WiTH COST DATA PROVIDED IN THE 1982 ASSESSMENT

I This appendix is provided in response to an inquiry of the Regional Water Quality

Control Boards staffs on August 29, 1985 regarding the comparison of cost and I economic information in this report with that provided in the 1982 Assessment of

Alternatives.

I COST AND ECONOMIC DATA INCLUDED IN THE 1982 ASSESSMENT

I The Assessment of Alternatives to Reduce the Losses of Striped Bass at the

Contra Costa and Pittsburcj Power Plants (TERA, 1982) included detailed

I

information, data, and calculations regarding the capital and operating costs of

alternatives considered in that study along with estimates of the dollar benefits I associated with each alternative. Such cost and economic information was

provided in various sections of the 1982 report, and was presented in several

I

tabular formats. The methodologies for calculating major economic and cost

factors were also discussed in Appendix E of the document.

I Provided below is a brief description of the method of presentation of data in the

1982 report using an example alternative (variable speed motor controls) from

I

that study. The next section of this appendix describes the cost methods used in

this 1985 study for the alternative, and is presented to facilitate the review and I . comparison of cost data in the two reports.

I

Cost information concerning the use of new pump motors with variable

frequency motor controls (VSDs) was presented in the following tables of the

I

1982 assessment: ~

I E5-73.3 A-I

C--048586

C-048586
!

Table I-S Summary Assessment of Alternatives

I

Table 3.5-8 Estimated Costs for VSDs

Table 3.S-9 Levelized Power Costs and Savings

i

Page b,-21 Summary of Levelized Annual Costs (Savings)

Appendix E.4 Example Calculation of Annual Costs

I

Ao Table I-S

!

The cost information presented in Table l-S~ page 140 of the 1982 reports

I

expressed the costs of the VSD alternative in terms of both ANNUAL COSTS

(SAVINGS) and TOTAL LIFETIME COSTS (SAVINGS). The values shown for

i

ANNUAL COSTS (SAVINGS) were taken directly from Table 3.S-9 and express

the "costs" (as a negative number if the dollar cost of the alternative is greater

than its economic benefit) or the "savings" (as a positive number if the dollar

I benefit is greater than its cost). The TOTAL LIFETIME COSTS (SAVINGS)

VALUE expressed the cost of the alternative as a total amount by multiplying

I

the annual cost by the life of the alternative. In the case of VSDs at Pittsburg

! _b,~ the ANNUAL COST was shown as $172~000 per year. The TOTAL LIFETIME

I

COST was shown as $2.8 million ($172~000 x !~; yr. life).

i

B. Tables 3.5-8 and 3.5-9

Table 3.5-8s page 3.5-2b, s presented the capital and labor costs for installing

I VSDs on each of the four unit groups at the Contro Costa and Pittsburg power

plants. The Capital Costs line of that table was derived from actual engineering

I

estimates made at the time of the study. All other lines (or components of cost)

were calculated using factors specific to the plants and to economic calculations

I

using 1982 values. The final line of the table titled LEVELIZED ANNUAL

REVENUE REQUIREMENTS converted TOTAL COST for o unit group into an

I

ANNUAL COST using factors presented in Appendix Table E-3. .:_

Table 3.5-9 showed the details of this annual cost calculation along with the

I estimated SAVINGS that would result from use of the alternative. The

I E5-73.3 A-2

I

C--048587

C-048587
I difference between LEVELIZED ANNUAL COST and ANNUAL OPERATING

I

SAVINGS yielded the NET ANNUAL SAVINGS (COST) of the alternative.

Bo Page b,-2 I I

The summary information on page ~-21 of the 1982 assessment simply restated I the ANNUAL COST (SAVINGS) value taken from Table 3.5-9. The cost value

shown on this page is the same as NET ANNUAL SAVINGS (COST) as noted

I

above under the description of Table 3.5-9.

I

C. Appendix

The example calculations presented in Appendix E,~ of the 1982 assessment were

I

intended to illustrate the method used to determine the ANNUAL OPERATING

SAVINGS value shown in Table 3.5-9. in the example shown~ the ANNUAL I OPERATING SAVINGS was calculated by determining the difference between

the energy costs of operating constant speed pumps versus pumps with VSDs.

I

The calculations of ANNUAL OPERATING SAVINGS were used to calculate NET

ANNUAL SAVINGS (COST) of the alternatives.

I

COST AND OPERATING DATA INCLUDED IN THE 1985 RE-EXAMINATION

I The major components of cost and net benefit (or loss) included in this report can

be directly compared to the costs shown in the 1982 assessment. The only

I changes in cost values between the two reports are:

I

o Engineering estimates of the equipment required for the

alternatives and the cost of such equipment have been

done using 1985 cost factors and current conditions of

I

existing systems at the power plants.

o The cost factors for labor~ contingency~ level annual fixed

i

charge rates~ etc. are 1985 values and differ from those

factors used in ! 982.

o The current PGandE methodology (i.e., step-by-step I

procedure) for calculating total annual costs differs

slightly from that used in 1982. These calculation

I E5-73.3 A-3

C--048588

C-048588
methodologies, however, yield comparable values for

TOTAL ANNUAL COST.

o The ANNUAL COST of each alternative, and thus the

NET ANNUAL COST. (SAV)NGS), has, been .calculated for a range oteconom~c ~ives ~wz. ~u, i~ aria 20-yrs) in this

report. Such information provides additional details to

aid in decision making.

o Cost and economic information for the Contra Costa and

Pittsburg power plants has been presented in separate

tables during this study rather than in single tables

organized by unit group.

This comparison of 1982 versus 1985 economic and cost data can be illustrated as

follows:

The economic evaluation of VSD installations at the Contra Costa Power Plant is

shown in Table 2-~ of this report. The line entitled MATERIAL COST is

comparable to the line entitled CAPITAL COST in Table 3.5-8 of the 1982 study.

The line entitled TOTAL COST isdirectly comparable on both tables although

calculated using a slightly different calculation procedure.

The lines entitled ANNUAL COST (@ ~ yr life) in Table 2-~ are comparable to

the line entitled LEVELIZED ANNUAL REVENUE REQUIREMENT in Table 3.5-

8. The only difference between these tables is that an ANNUAL COST (or

REVENUE REQUIREMENT) has been calculated in the 1985 study for three

economic lives. Only one life (vizo the remaining life of the unit) was calculated

in the 1982 study.

The lines entitled NET SAVINGS (COST) $~ yr life in Table 2-~ are directly

comparable to the column entitled NET ANNUAL SAVINGS OR COST in Table

3.S-9, and show the net cost associated with an alternative. This value is a

measure c~f the economic merits of an alternative considering the expenditures

required to install it and the resultant increase or decrease in operating costs.

- The value termed TOTAL LIFETIME COST in the 1982 study (see A. ab~5~e) has

not been calculated or presented in the ~985 assessment; however, the TOTAL

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LIFETIME VALUE of an alternative can be easily determined by multiplying the

NET SAVINGS (COST) line by the appropriate life shown, This calculation would

yield the following results if done with the data in Table

TOTAL LIFETIME COST

Net Savings (cost) @ I 0 yr life ($821,959) ($8,219,590)

Net Savings (cost) @ I 5 yr life ($592,917) ($8,893,7.55)

Net Savings (cost) @ 20 yr life ($471,625) ($9,432,500)

E5-73.3 A-5

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