DCL-86-118, Annual Environ Operating Rept (Part B),1985

Annual Environ Operating Rept (Part B),1985

ML20197B298
Person / Time
Site:	Diablo Canyon
Issue date:	12/31/1985
From:	PACIFIC GAS & ELECTRIC CO.
To:
References
DCL-86-118, NUDOCS 8605120501
Download: ML20197B298 (19)

Text

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DIABLO CANYON POWER PLANT ANNUAL ENVIRONMENTAL OPERATING REPORT (PART B) 1985 PACIFIC GAS AND ELECTRIC COMPANY

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PACIFIC GAS AND ELECTRIC C0t1 pat 4Y DIABLO CANYON POWER PLANT 1985 ANNUAL ENVIRONMENTAL (NON-RADIOLOGICAL) OPERATING REPORT 1

1.0 INTRODUCTION

1 2.0 ENVIRONMENTAL MONITORING..............................................

1 2.1 AQUATIC..........................................................

2.1.1 NPDES Permi t Annual Progre ss Reports . . . . . . . . . . . . . . . . . . . . . . 1 2.1.2 NPDES Permi t Nonrouti ne Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.1.3 Env i ronme n tal I nve s ti ga ti on s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2

2.2 TERRESTRIAL.......................................................

2.2.1 E ro s i on C on trol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.2.2 Herbi ci de Appli cati on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2.3 C A-SLO-2 Archa eol og i cal S i te . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2.3.1 CA-SLO-2 Si te Man a gemen t . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2.3.2 Chuma sh Indian Access Agreement. . . . . . . . . . . . . . . . . . 4 3.0 UNUSU AL OR IMPORTANT ENV IRONMENTAL EVENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.0 P L ANT CO N S I STENCY RE 0V I REME NTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1 DE S I G N CH AN G E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5

5.0 PLANT REPORTING RE0VIREMENTS..........................................

5.1 (EPP) N0NCOMPLIANCES............................................. 5 5

5.2 DESIGN CHANGES-UNREVIEWED ENVIRONMENTAL QUESTION.................

5 5.3 NONROUTINE REP 0RTS...............................................

6.0 EPP AUDIT............................................................. 6 ATTACH! TENT 1 SUtttARY OF ENVIRON!! ENTAL INVESTIGATIONS AT DIABLO CANYON, 1985

1.0 INTRODUCTION

The Pacific Gas and Electric Company (PGandE) has committed to minimize the impact of the Diablo Canyon Power Plant (DCPP) facility construction and operation on the environment. The 1985 Annual Environmental Operating Report ( AEOR) is being submitted in accordance with the  ;

objectives of the Environmental Protection Plan (EPP) as required by i Facility Operating Licenses DPR-80 and DPR-82, to demonstrate that the plant is operating in an environmentally acceptable manner.

2.0 ENVIRONMENTAL MONITORING 2.1 AQUATIC 2.1.1 National Pollutant Discharge Elimination System (NPDES)

Permit Annual Progress Reports A revised DCPP NPDES permit (Amended Order No.85-101, NPDES No. CA0003752) was adopted by the Regional Water Quality Control Board (RWQCB), Central Coast Region, on July 12, 1985. Reporting Requirement No.5 of the permit iequires PGandE to submit annual Provision D.4.a. (Thermal Effects Monitoring Program) and D.4.b. (Impingement and Entrainment 316(b) Studies) progress reports to the RUQCB by May 1 of the subsequent year. A copy of these reports will be submitted to the Nuclear Regulatory Commission (NRC) at the time of submittal to the RWQCB.

2.1.2 NPDES Permit Nonroutine Reports [EPP Section 3.2]

The following nonroutine reports were submitted to the RWQCB in 1985. All nonroutine incidents involving temperature occurred priog to the issuance of the new permit, which contains a 22 F condenser temperature differential limit.

In accordance with EPP Section 3.2, copies of these reports were forwarded to the NRC as'they were issued.

May 20, 1985 Exceeded the 200 F condenser tempera-ture differential limit in the NPDES permit during March,1985. Reported in the April,1985 monthly report.

May 23, 1985 Release of condensate demineralizer ef fluent to Diablo Creek.

June 20,1985 Exceeded the 20 0F condenser tempera-ture differential limit in the NPDES permit in 11ay and June,1985.

Reported in the May,1985 monthly report.

July 19,1985 Exceeded the 20 F condenser tempera-ture dif ferential limit in June.

Reported in the June,1985 monthly report.

2.1.3 Environmental Investigations Environmental studies have been performed at DCPP since 1966 and the results are published by PGandE's Department of Engineering Research (DER) in an annual volume entitled

" Environmental Investigations at Diablo Canyon". Copies of the report are available upon request. Attachment 1 to this report contains summaries of the studies performed in 1985.

2.2 TERRESTRIAL 2.2.1 Erosion Control [EPP Section 2.2]

Erosion control measures made within the DCPP associated transmission line corridors consisted of the installation of two 12 inch culverts and access road grading on the Diablo-Gates 500kV line at towers 20/83, 20/82, and 19/81.

No other erosion control work was required on these lines.

All of the plant associated 500kV lines were patrolled and and inspected three times during 1985.

Several measures were made to minimize erosion within the the CA-SLO-2 archaeological site: Road and drainage ditches were patched, graded, and cleaned. Spoil piles were distributed, and graded, and the areas subsequently hydroseeded. Grading and rip-rapping of areas above and adjacent to the northeast portion of CA-SLO-2 site occurred.

General erosion control methods utilized at DCPP during 1985 consisted of:

1. The use of erosion / siltation co- rol measures (siltation fences, haybales, etc.) during construction of facilities requiring earthwork.

2. Review of all engineered cut and fill slopes for slope stability ant erosion potential .

3. Placement of drainage ditches at the appropriate locations to minimize stormwater run-off on cut and fill slopes.

4. Juting and hydroseeding or rip-rapping of all finished cut and fill slopes.

5. Finished paving and landscaping provided around building areas.

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j 2.2.2 Herbicide Application [EPP Subsection 4.2.1)

No herbicide was applied within the OCPP associated trans-mission line corridors in 1985.

In January,1985, herbicide was applied to the DCPP 230kV and 500kV switchyards. A ground application of AATREX 90, EPA I.D. Number 100-585- AA, at 10 pounds per acre, and AMIZOL, EP A I .D. Number 264-119-AA, at 1 pound per acre, was applied to the approxinately the 16.1 acres.

Other minor applications of herbicides within the plant site boundary included the following:

DATE LOCATION PRODUCT EP A I .D. NO. ACRES RATE 03-19-85 Various (site AMITROL 359-564 2.4 2 lbs/

roads, parking BUCTREL acre areas, firing range, dog kennels) same as above BROMICAL 264-204-AA 2.4 0.5 gal./

acre 05-15-85 Access and watch tower roads ROUND-UP 524-308-AA 1.4 1 gal./

100 gal, water 2.2.3 Preservation of Archaeological Resources

[EPP Subsection 4.2.23 2.2.3.1 CA-SLO-2 Site Management There were no disturbances of the CA-SLO-2 site inconsistent with the allowable uses under the Archaeological Resources Management Plan ( ARMP) i'n

1985.

Monitoring of planned activities within the site boundary as required by the ARMP included: the observation of the renoval of a temporary 12kV pole line, an archaeological survey of the pipelines for the makeup water reverse osmosis system and rotor storage building, and inspection of leveled spoil piles, groundwater monitoring well sites, gunite ditch repair, and hydroseeding of the laydown area.

Monthly photographic monitoring of 23 CA-SLO-2 stations was conducted by a PGandE archaeologist in accordance with a departmental ARMP implementing procedure. On September 24, 1985, the monthly

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e monitoring requirenent was revised to quarterly with the concurrence of the California State Historic Preservation Officer.

2.2.3.2 Chumash Indian Access Agreement In 1982, a controlled : site access agreement was enacted between PGandE and the Santa Ynez Band of the Chumash Indian Tribe. In March, 1985, the DCPP flanager received a letter dated February 19, 1985 from the Elders of tha Coastal Band of the Chunash Nation expressing a concern about a possible disturbance of the archaeological Indian remains at DCPP. A PGandE archaeologist investigated the complaint and found no evidence of a disturbance of cultural remains. By letter dated March 12, 1985, the Elders of the Coastal Band of the Chumash Tribe were invited to visit the site with their consultant (s). The Coastal Band did not accept the invitation to visit the site. No other visits were requested during 1985.

3.0 UNUSUAL OR IMPORTANT ENVIRONMENTAL EVENTS [EPP Section 4.1]

No occurrence of an unusual or important event that would indicate or could result in a significant environmental impact causally related to station operation occurred in 1985. Anticipated changes in the distribution and abundance of Diablo Cove species as a result of thermal discharge are reported in the 1985 Thermal Effects Monitoring Program (TEMP) Annual Report.

4.0 PLANT CONSISTENCY REQUIREMENTS [EPP Section 3.0]

4.1 DESIGN CHANGES There were no design changes which were considered to involve an unreviewed environmental question in 1985. There were several design changes which were considered to have the potential to affect the envircnment. A summary of the environmental evaluation for each of these design changes is presented below:

DCO-M-31394 Seawater Reverse Osmosis System This system was installed in ordt- to provide an additional reliable source of makeup water for Units 1 and 2 at DCPP. During operation this system discharges trine which has more than twice the salt content of

. andard seawater. The environmental evaluation included an analysis of the system discharge, erosion potential, and chenical usage. It was determined that the discharge was to be added to the National Pollutant Discharge Elimination Systen (NPDES) permit and treated as a low volume waste, no erosion potential existed, and all chemicals would be properly stored and disposed.

Therefore, the design change was considered not to be an unreviewed environmental question.

DCO-M-29952 New Laundry and Radwaste Storage Facility The proposed laundry facility was being installed to replace an existing temporary facility. The permanent facility was discussed in the plant safety analysis, and volume limits in the NPDES permit will be met. The design change was determined not to involve an unreviewed environmental question.

DC2-C-32697 Installation of Two Transformer Deluge and Spill Prevention Sumps in the DCPP Plant Yard These sumps were proposed for installation in order to provide for a transformer deluge and chemical spill ,

retention system to meet the requirements of the Spill '

Prevention Control and Countermeasure (SPCC) plan as required by 40 CFR112. These sumps have been incorporated into the NPDES permit, and are expected to have a positive af fect on the environment by decreasing the potential for oil and chemical spills to Diablo Creek and the Pacific Ocean.

5.0 PLANT REPORTING REOUIREMENTS [EPP Section 5.03 5.1 EPP NONCOMPLIANCES There were no EPP noncompliances during 1985.

5.2 CHANGES IN STATION DESIGN There were no changes in station design or operation, tests or experiments which involved a potentially significant unreviewed environmental question in 1985.

5.3 NONROUTINE REPORTS There were no EPP nonroutine reports in 1985.

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6.0 EPP AUDIT [EPP Section 5.1)

The PGandE Quality Assurance Department performed an audit of the implementation of the EPP in flarch,1985. No items of noncompliance were found.

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ATTACHMENT 1 f

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SUMMARY

OF ENVIRONMENTAL STUDIES CONDUCTED dTDIA.Bl.0CANYONIN1985 9

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1. NPDES MONITORING PROGRAM AND T0XICITY STUDIES During 1985 PGandE received a new NPDES permit (Order 85-101) from the Regional Water Quality Control Board. For the most part,

-the NPDES self-monitoring program as required by the Board was the same. PGandE's Department of Engineering Research (DER) maintained responsibility for receiving water monitoring and the Chemistry and Radiation Department at Diablo Canyon Power Plant maintained responsibility for effleunt monitoring.

Major elements included in the monitoring program were the Thermal Effects Monitoring Program (TEMP) and the 316(b)

Demonstration Study reported annually to the Regional Board, U. S.

NRC, and the California Department of Fish and Game by May 1; and physical oceanographic studies, and effluent toxicity studies reported to the Regional Board monthly.

2. HEAT TREATMENT OPTIMIZATION STUDIES The Diablo Canyon Power Plant Heat Treatment Optimization Study was initiated in early 1963. The purpose of this 5:udy is to develop

-a site specific heat treatment procedure which will maximize marine biofouling control and minimize potential environmental impacts. The study has been designed to satisfy requirements of Provision D.6 of the Diablo Canyon NPDES Permit 82-24 Phase I of the study consisted of a laboratory determination of the thermal tolerance of major biofouling species. This work was completed in 1984. In Phase II, actual fouling comunities were cultured in a sidestream of the power plant's cooling water flow to determine growth rates and periods of peak settlement. These fouling organisms were subjected to simulated heat treatment comprised of varying combinations of temperature, duration, and frequency. These variables were determined as a direct result of the Phase I experiments and were verified in terms of effectiveness during Phase II. Physical model studies were conducted in Phase III to determine the areal extent of the discharge plumes resulting from the heat treatment procedures simulated in Phase II.

This information was then coupled with laboratory studies to predict the environmental consequences of heat treatment temperatures under various physical and environmental conditions. In addition, an engineering assessment of alternatives to heat treatment for the control of biofouing was added to Phase III during 1984. Both Phase II and Phase III were completed in 1985. The combined findings of these first three portions of the Heat Treatment Optimization Study were used to assemble the criteria deemed effective for actual power ,

plant demusseling. Demusseling operations conducted at Diablo Canyon during August and November of 1985, based on these findings, proved to'be successful.

The Heat Traatment Optimization program has now entered Phase IV in which marine biofouling shall be monitored and used as an indicator of demusseling need and success. The continued scrutiny of this dynamic community of organisms will help maintain a site specific heat treatment program which maximizes biofouling control while minimizing environmental effects.

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3. WHEELER J. NORTH ECOLOGICAL STUDIES: 1985 l

• During 1985, three intertidal biological surveys were conducted in May, August, and December. A subtidal biological survey was done in December.

Subtidal phaeophyte populations were estimated in May, August, and December. In this study, five species of brown algae are counted in ten quadrats and five different sites to determine the effects of the thermal effluent on the brown algal population as a whole.

A full shorewalk was conducted in May 1985. The entire Diablo Cove shoreline was walked to assess the condition of plants and animals from the water line to the cliff base. Also noted during the walk was the physical condition of each area as to storm damage during the winter and boulder, cobble, and sand movement. A mini-shorewalk was done in December af ter both units had been operating for a time to assess the the shoreline on both sides of the discharge structure where the thermal effects might be the greatest.

4. FISHERIES STUDIES Commercial Passenger Fishing Vessel (CPFV or partyboat) catch and effort have been intensively monitored for six years as part of a baseline study conducted prior to commercial operation of Diablo Canyon Power Plant. Summaries of the species composition, catch, and effort since 1980 were prepared. Size composition data for seven selected rockfish species (Genus Sebastes) were analyzed and reported. An overall downward trend in the fishery since 1982 has been identified, but is unrelated to commercial operation of the power plant in 1984. The decline in the fishery may be related to effects of El Nino oceanographic conditions, fishing pressure, heavy storm activity, or combinations of these f actors. Continued monitoring of the fishery will assist investigators in assessing recovery or possible further decline.

5. OBSERVATIONS OF THE SEA OTTER ENHYDRA LUTRIS POPULATION BETWEEN POINT BUCH0N AND RATTLESNAKE CREEK SAN LUIS OBISP0, CALIFORNIA ,

The monitoring of the southern sea otter continues. Sea otter numbers, raf ting sites, and incidental feeding activities were recorded three times a month from January through December 1985.

Subtidal sea urchin and abalone density surveys, night activity monitoring, and tagged sea otter observations were also conducted.

The sea otter population within the study area remains stabilized and well established. Females and pups dominate the area, accompanied by several territorial males. The most conmonly occupied resting sites include Windy Foint, Lion Rock, Intake Cove, and Pecho Rock. Feeding observations indicate that small shelled molluscs and other incidental food items represent about half of the sea otters diet.

Sea urchin densities renain below detectable levels and abalone densities, although still low, have increased to approximately 2/100 meter.

6. OBSERVATIONS OF THE GRAY WHALE MIGRATION IN THE VICINITY OF DIABLO CANYON A census of the California gray whale, Eschrichtius robustus was conducted offshore of the Diablo Canyon Power Plant for the fourth consecutive season to determine the number of animals passing through the anticipated area of the thermal plume, their time of passage, and

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distance from shore while in migration. A total of 94.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> over 35 days were spent collecting data. A study corridor 1,830 meters (6,000 feet) wide was used based on discharge plume predictions.

During the 1984-1985 migration, southbound whales passed the plant between December 17, 1984, and February 20, 1985. The northerly return was separated into the typical two phases. The first (February 15 through March 15) consisted of males and females without calves and the second (March 15 through May 6) was comprised of cows and calves. Numbers passing within the 1,830 meter corridor reached 12.7 whales per hour (WPH) during the southerly leg and 13.3 and 6.0 WPH during the northerly movement, respectively. The largest pod contained 11 individuals. Mean pod size was 2.0 during both southerly and northerly movement. Based on 94.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> of observation, an estimated 10,683 whales passed through the 1,830 meter corridor on the southerly migration, while 9,377 whales passed through the northerly migration. Yearly variation in the numbers of whales observed seems to be related to their distance offshore. Thus the percentage passing through our observation zone varies rather than the total number of whales passing the central California coast.

7. A NUMERICAL ANALYSIS OF ALGAL COMMUNITY STRUCTURE IN DIABLO COVE, CALIFORNIA A study was conducted to examine the intertidal plant community structure in the vicinity of Diablo Cove, in central California.

Bimonthly surveys were conducted at several stations in the area of Diablo Cove. Each station consisted of three 30 meter transects i

running perpendicular to the shoreline. Qualitative data of species presence or absence were collected in 12 one-meter square quadrats along each transect. The ordination technique of Detrended Reciprocal Averaging was used to examine within survey-station comunity structure. Results showed that differences in structure between surveys and stations are a result of differences in species composition and dominance. Environmental data collected in the study i

area were used with the biological data as input to the multivariate l

technique of Canonical Correlation. This method examines shared patterns between two data sets. Results from Canonical Correlation showed that changes in biological comunity structure correlate well with measured physical data. These physical data are a rough measure of seasonal change in local oceanic conditions.

8. OCEANOGRAPHIC STUDIES 1985 Physical and chemical oceanographic studies were conducted by

! Pacific Gas and Electric Company in the vicinity of the Diablo Canyon l

Power Plant during February, June, and September, 1985. The temperature, salinity, and dissolved oxygen concentrations were i monitored at 27 stations in the vicinity of Diablo Canyon.

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Additionally, pH was sampled at 12 of the locations in and near Diablo Cove. Temperature profiles from surface to bottom were made at each station. Water samples used for salinity, dissolved oxygen, and pH determinations were collected just below the surf ace, at the mid-water column, and 0.5 meters above the bottom at each station.

The tracking of multiple surface drifters (drogues) was conducted thirty times during the year to provide ancillary information on current patterns offshore of Diablo Canyon.

9. SEAWATER DENSITIES IN THE VICINITY OF DIABLO CANYON POWER PLANT 1972 - 1985 During 1985, oceanographic data were collected at 24 stations along the California coastline in the vicinity of Diablo Canyon, and at 3 stations in Diablo Cove. Seawater densities, expressed as sigma, were calculated from these data and density contours were drawn parallel to the coastline. The results will be part of a data base of density information which began in 1972. This data base will be used to detect changes in the seawater density at Diablo Canyon which is a useful indicator of the spatial and temporal distribution of a thermal discharge (Orvosh,1979).

10. RECEIVING WATER TEMPERATURE STUDIES DURING POWER ASCENSION TESTING OF UNIT 1 Power ascension testing of Unit I at DCPP began in November, 1984. A field data collection program was initiated to describe the three-dimensional receiving water temperature and velocity field. A total of 29 tests were conducted at several power levels (30, 50, 75, 95, and 100 percent), plus during heat treatment. Temperatures in the upper water column were measured along transects and temperature profiles were taken at fixed stations. Drogues were released and tracked to determine plume velocities and temperature decay and to determine ambient currents.

The analysis of the data concentrated on 11 of the 29 tests. We

• found that the plume trajectory was towards Diablo Rock, with the majority of warm water exiting the west entrance of Diablo Cove.

During several tests, a splitting of the plume was observed within Diablo Cove. The surf ace area of the 10 degree F isotherm varied between 5 and 50 acres. Centerline temperature decay with Diablo Cove was found to be relatively constant among tests. The maximum plume depth varied between 15 and 35 feet, with deeper plumes generally occurring with higher waves. As much as 15 acres of the bottom in the shallow regions of Diablo Cove were estimated to have temperatures above ambient of at least one-half the power plant temperature rise.

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11. CHARACTERIZATION OF RECEIVING WATER TEMPERATURES FROM DIABLO CAYON POWER PLANT DURING POWER ASCENSION TESTING OF UNIT 2 This report documents a field data collection program at Diablo Canyon Power Plant during power ascension testing of Unit 2 in 1985.

The testing program was intended to describe the behavior of a surface buoyant jet / plume discharged from the plant into the surrounding receiving waters. Testing areas included both the far-field offshore area and the near-field discharge cove area.

In the near-fibld region, temperatures in the upper 10 feet of the water column were measured along lateral and longitudinal transects and vertical temperature profiles were made at reference st ations. Lagrangian velocities were measured using drogues, and Eulerian velocities were acquired with electromagnetic current meters at both entrances of the discharge cove. In the far-field region, the offshore plume was mapped to include the one degree Celsius isotherm.

Jet / plume centerline temperature decay, the lateral spreading, penetration depth, offshore surface isotherm and stratification levels are presented and discussed in the light of different discharge and environmental conditions. Results are compared to other studies.

12. MODEL VERIFICATION STUDY OF THE THERMAL PLUME DISCHARGE GE0 METRY AND TEMPERATURE The main purpose of the work was to obtain agreement between the thermal plume as measured in the prototype and that measured in the physical model.

Three major mechanisms related to the cooling water flow were investigated. These mechansims were:

- bathymetric changes to the model based on depth soundings;

- alteration of the bathymetry and roughness near the discharge structure using gravel; and

- the use of waves during test runs in the model.

Correlation between the model and the prototype temperatures and l

plume behavior was documented. In general, the plume geometry of the model compares well with the prototype.

13. NEARSHORE WAVE DATA MEASUREMENTS Nearshore wave climate was monitored January through December, 1985. The wave monitoring program consists of determining the deep water wave direction, and wave height and period. The study utilizes data collected using a clineameter which is installed at an elevated position onshore on the. slope of Green Peak, and an accelerometer buoy located at the 75 foot contour near the Intake Cove.

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14. UNIT 1 HYDRAULIC MODEL VERIFICATION TESTS During 1985, an extensive series of model tests were performed to thermodynamica11y verify the physical model as required by the Nuclear Regulatory Commission (NRC). The basic approach consisted of running the model for the plant discharge and ambient current and tide conditions that existed during the Unit 1 power ascension tests and comparing prototype and model temperature distributions both within and outside Diablo Cove. When the model results disagreed with the field data, the reasons for the disagreement were investigated and the model modified to remove the source of the disagreement. Tests were then performed over a wide range of plant and ambient conditions to ensure that the model was truly verified and not simply calibrated for a unique set of conditions.

Quality Assurance procedures were developed to ensure that correct and repeatable procedures were used in operating the model, recording data, and documenting the storing of test results.

Statistical techniques were developed to evaluate the agreement between model and field data. The results indicated that the model simulates the behavior of the prototype over a wide range of Unit 1 operating levels and ambient conditions. Good agreement was obtained both inside Diablo Cove and offshore, including agreement between horizontal and vertical temperature profiles, and plume trajectories and configurations.

15. DIABLO CANYON CONTINUOUS CURRENT MEASUREMENTS JUNE 1984 THROUGH JUNE 1985 Currents measured during this reporting period were generally similar to previous years.

Predominant flow directions were coast-wide, parallel to the coastline an bathymetric contours. The frequency of occurrence of upcoast and downcoast flows were generally the same. The seasonability of current directions was similar to previous data with upcoast flow predominanting in the late sumer through the winter months followed by a persistent downcoast trend in the spring and early summer months. During transitions between these predominant flow regimes, currents showed reversing flows with periods ranging from days to weeks.

Some differences in measured currents occurred during this period. Average current speed was 0.26 knots. During past years, average speeds have been approximately 0.20 knots. Peak speed recorded during this samping interval was 1.5 knots, the same as last year's peak. In previous years this value did not exceed 1.3 knots.

The percent occurrence of speeds greater than 0.50 knots was 12.6 percent during this period, 15 percent during the previous year's sanpling, and averaged less than 10 percent in the majority of data collected over the past five years.

Strong flow reversals were again comon in this year's records, l

16. STUDY OF NEARSHORE CURRENT, WIND, AND TIME IN THE VICINITY OF DIABLO CANYON POWER PLANT The variation of nearshore current significantly changes the dilution rate and trajectory of the thermal discharge from Diablo Canyon Power Plant. To accurately predict the characteristics of the thermal discharge.and the corresponding environmental effects, the nearshore current has to be known.

To determine the structure of the nearshore current, continuous records of current, wind, and tide measured in Diablo coastal area by Pacific Gas and Electric Company were analyzed. More specifically, the study focused the following questions:

- What are the effects of locally generated wind and tide on the nearshore current?

- Does the nea: J.re current predictably respond to the variations of the above mentioned factors?

- Is it possible to identify a predominant forcing mechanism (s) that generates the current?

- What are the effects of the California current system on the nearshore current in the Diablo Canyon coastal area?

The current and wind velocity records for 1984 were resolved along the shore normal and shore parallel directions. The resolved components of current and wind indicate that both current and wind are predominantly shore parallel. Moreover, the wind was consistently northwesterly throuhout the year, except during November and December when reversals in wind direction occurred. Unlike the wind, the current frequently changed direction from north to south and vice versa. Further analysis shows that both current and wind records are composed of high (short period) and low (long periods on the order of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) frequency components.

Separating the low (smoothed) and high (residual) frequency '

components of current, wind, and tide, and comparing the current-wind, and current-tide records with similar frequencies revealed that:

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- The smoothed current and wind were highly correlated and the

current closely followed wind, indicating that at low frequencies, the current is primarily driven by wind.

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- The residual components of current-wind and current-tide were highly correlated as long as the current generated by tide was in the same direction as the one generated by the residual wind. However, the correlation was poor when these two currents were in opposite directions. Also, the residual current was fairly in phase with the tidal record, contrary to the current-tide relations in bays and deltas where a lag exists between peak current and tides.

- These comparisons suggest that the residual current is primarily generated by both wind and tide.

- In addition, a very low frequency current was detected in the records (periods on the order of a month) which seem to represent the seasonal nearshore current. It was consistently northward (at least during 1984) with its peak being during the summer. During the same period, the seasonal current at offshore is southward. The occurrence of the northward nearshore current and southward offshore current during the same period suggests the existence of a large scale eddy off Diablo Cove. Such a gyre has also been observed between Cape Mendocino and Point Conception in the dynamic topographic maps of Hickey (1978).

The nearshore current at any instant of time may be represented by the sum of three types of currents: smoothed current, residual current, and seasonal current. In addition, the records indicate that the smoothed current is primarily driven by wind, while the residual current is driven by both wind and tide. The seasonal current appears to be related to the California Current system.

Based on these observations, we examined the applicability of a simple one-line current model for predicting the smoothed current.

The only input required for the simple model are the smoothed wind record and water depth. The comparisons of the observed and predicted current records show that the model fairly accurately predicts the changes in current magnitude and direction. However, in general, the observed current records slightly lag behind the predicted current. The lag is expected because the inertia term is neglected in the model.

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=E1"E'U$.a= April 30, 1986 i PGandE Letter No.: DCL-86-il8 Mr. John B. Martin, Regional Administrator U. S. Nuclear Regulatory Commission, Region V 1450 Maria Lane, Suite 210 Hainut Creek, CA 94596-5368 Re: Dotket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Annual Environmental Operating Report, Part B

Dear Mr. Martin:

Enclosed is the 1985 Annual Environmental Operating Report (Part B) for Diablo Canyon Units 1 and 2, submitted in accordance with Subsection 5.4.1 of the Environmental Protection Plan, Appendix B to Facility Operating Licenses Nos. DPR-80 and DPR-82.

Kindly acknowledge receipt of this material on the enclosed copy of this letter and return it in the enclosed addressed envelope.

Sincerely, J. O' iffer Enclosure cc w/ enc: R. H. Carr L. J. Chandler M. M. Hendonca B. Norton R. B. Samworth H. E. Schierling S. A. Varga CPUC Document Control Desk (18) cc w/o enc: Diablo Distribution f 9 -

7 08395/0044K/RHS/1007 h

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PGandE Letter No.: DCL-86-118 ENCLOSURE 0839S/0044K