ML20126C123
| ML20126C123 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/17/1980 |
| From: | Elashry M TENNESSEE VALLEY AUTHORITY |
| To: | Harvey S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| NUDOCS 8003260600 | |
| Download: ML20126C123 (8) | |
Text
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Mr. Sanford W. Harvey, Director Enforcement Division U.S. Environmental Protection Agency Region IV l
345 Courtland Street, NE.
Atlanta Georgia 30303
Dear Mr. Harvey:
SEQUOYAH NUCLEAR PL\\NT - NPDES PER'!IT NO. TN0024450 - OPERATION FISHERIES MONITORING PROGRAM A TVA letter to Mr. Charles 11. Kaplan dated March 13, 1979, transmitted intormation concerning our operational monitoring program for fisheries j
at Sequoyah Nuclear Plant in support of our NPDES permit application.
As a result of additional information obtained since originally proposing this program, we have decided to revise the monitoring program to enable us to develop an improved data base and to reduce monitoring program expenses.
Two reports entitled, " Amended Fish Entrainment Operational Monitoring Plan for Sequoyah Nuclear Plant" and " Rationale for the Proprosed Changes in the Fish Entrainment Operational Monitoring Plan for Sequoyah i
Nuclear Plant" are enclosed describing these changes and the reasons for them.
If you have any questions concerning our monitoring program, please let me know.
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Sincerely,
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Mohamed T. El-Ashry, Pl..D.
Director of Environmental Quality Enclosures cc:
See list on page 2 h
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8003.260 %
. Mr. Sanford W.
Harvey cc (Enclosures):
Ms. Suzanne Kebiusek Environmental Project Manager Environmental Project Branch 2 Division of Site Safety and Environm2ntal Analysis Mail Stop P-522 U.S. Nuclear Regulatory Contmission Washington, DC 20555 Mr. Elmo Lunn, Director Division of Water Quality Control Tennessee Department or Public Health 621 Cordell Hull Building Nashville, Tennessee 37219 Mr. Jack McCormick, Regional Engineer Tennessee Department of Public Healt'.i 2501 Milne Street Chattanooga, Tennessee 37406 Mr. Lee B. Tebo, Chief Ecology Branch Environmental Protection Agency College Station Road Athens, Georgia 30605 i
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RATIONALE FOR Tile PROPOSED CIL\\NCES IN Till: FIS!!
ENTRAINFIENT OPElt\\TIONAI. MONITORING PLAN FOR SEQUOYAll Stl CLEAR PLAST Three specific areas of change to the fish entrainment samp lin g plan for operational monitoring at the Sequoyah Nuclear Plant are being addrersed.
First, biweekly sampling is being proposed in lieu of weekly.
Second, CCW (condenser cooling water) intake sampling is being modified from a plan which called for samples to be taken in the intake embayment to one which calls for samples to be taken adjacent to the mouth of the intake channel skimmer wall.
The third change calls for sampling which will better accommodate the discharge dif fuser ' design and also give a better overall representatia, af the s;:ecific cross-sectirnal area of each transeet.
Biweekly versus Wek1v Sampling The original plan called for weekly sampling during the first year of operation and biweekly during all subsequent years.
When the drait study plan was developed, it was assumed that a considerable number of shif ts between cooling modes would occur during the first year of plant opetation.
It therefore was decided that a weekly sampling frequency would increase the probability of sampling during all three modes of operation.
Subsequent information nas indicated that ve ry few chan e,es in coolinq modes will take place during any year o f operation.
Based on this neu information, a plan of biweekly sampling will provide a suf ficient number o f observations for estimating entrainment under the dif ferer t operating modes.
Furthermore, since neither hi 4r nor closed mode operation will be needed until two-unit operation begins (March 198l), only open mode will occur in this first year of operat.lon (L980).
Since.CCW intake volume is l
virtually the same for open and helper mode operation, ent rainment ef fects of t
the two should be the sane.
Based on our experience at other locations in the Tennessee Valley indications are that biweekly and weekly sampling schedules yield comparabic results both in terau of tana collected and estimates of abundance.
Biweekly sampling should thus be fully adequate to determine the seasonal occurrence and abundance of Larval fish in the vicinity of the Sequoyah Nuclear Plant.
Intake Channel Sampling The original plan for the CCW intake channel sampling called for sampling within the intake embayment in both.the dredged ch1nnel portion and the shallow shoal areas on each side of the embayment.
Sampling within the intake embayment at Sequoyah Nuetear Plant poses three problems.
First, the embay:Leot has large shallow areas which may. serve as localized spawning habitat.
['ish eggs and larvae produced in these localized areas of the intake embayment can seriously compromise estimates of ichthyoplankton losses f rom the reservoir proper. Such errors would tend to inflate entrainment estimates and lead to erroneous impact assessments.
Furthermore, during closed made operat ton of the plant, water f rom the cooling towers is recirculated through the intake embayment back to the plant. This water will be at temperatures his;her than ambient reservoir water and could induce advan'ced spawning by some species of fish.
Such spawning, out of phase with the reservoir populations, would also lead to erroneous impact assessments since percent entralnment la based upon larval densities f rom ooth the reservoir proper md the lutake.
The third factor stema from the fact that during closed mode operation the water in the dredged portion of the lutake channel is mostly recirculated water with only a small f rat. tion of the total CCW being actually i-i l
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withdrawn f rom the reservoir proper.
In view of there facts, it is proposed that the CCW intake samples be taken adjacent to the reservoir.4tde of the skimmer wall.
Oblique tows parallel to the opening of the sktamer wall would ef feet trely sample waters drawn f rom the reservoir by the CCW intake. This sar:ipling approach minimizes many of the problems discussed above and yet adeq uate ly samples waters being removed frem the reservoir.
Reservoir Transect Sampling The original sampling plan called for a single midehannel station each transect with three strata sampled.(1.e.,
sdrface, middle, and at bottom waters). The current plan recommends two midchannel stations at each transect with two strata sampled (surface to mid-depth and mid-depth to bottom).
Sampling two open water stations will give horizontal distribution information not possible with a single midehannel station.
Two vertical strata are sufficient to identify basic vertical distribution patterns e The design of the diffuser pipes (two parallel pipes, one long and one short, extending approximately all the way across the channel and halfway across, respectively) provides additional justification for two midchannel stations, since a sin,:lc station would not adequately sample the area under the varying modes of discharge operation.
The need fo r sampling balance between t ransect.: further supports the plan of two channel staticus at each transuet. The origtnal samptlog plan called for shoreline and midehannel sampling at eaca transect. L:nder the revised plan, only the shoreline with signif teant overbank area will be sample l, the plant site where both banks w1LI be sampled. The shore without except at from
. appreciable overbank is not expected to be ut,;nif teantly dif ferent midehannel areas, and,nsequently should not be sampled except at the plant
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LFC: CTS:VRC 3/8/80 Prepared by Lee Graser and Carl Suor i
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1 A:lENDED FICil ENTPAIMIENT OPERATIONAL SiONITORING PLAN FOR SEQl'OYAll :ICLEAR PL\\NT Ichthyoplankton samplin;; will be conducted on a btweekly basis during the spring and summer months (march-Au :ust) near Sequoyah Nuclear Plant. Objectives of these studies will include:
1.
To estimate entrainment losses of young fish and eggs from Chickamauga Reservoir as a result of the operation of Sequoyah Nuclear Plant.
2.
To deterntine if entratnment losses result in measurably reduced abundance of fish and eggs downstream of Sequoyah Nuclear Plant.
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To determine if losses which may occur are replaced by production i
downstream of the plant, t
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To estimate the impact of entrainment losses on the fish populations of Chickamauga Reservoir.
Entrainment data will be collected f rom the plant CC'4 intake at the mouth of the skimmer wall where the waterflow is representative of the water being withdrawn from the rese rvo i r.
Reservoir data will be collected at three transects near the plant. These cransects are located adjacent to :.he intake at TR>l 484.8, just downstream tf the discharge mixing zone at El' 1 432. 7, and appro:dma tely J
thr ee miles downs t reu.a trom the diffusers at TR:t 4 79. 4 Siethods of data collection will be similar for each transect.
Full stratum samples will be taken near one s ioreline on the overbank area at the lower two transaets, and near both shorelines at the plant transcet. The m.idchannel area at each tranunct will be sampled by taking stratified samples, i.e.,
equally sampline, shallow
4 and deep waters at each of two stations in the channel area. A total of approximately 600 samples are expected to be collected each year.
Mter analysis of the initial data, adjustments to the sampling technique and/or stations may be i.ap ten.ented to improve the quality of the monitoring program.
Samples will be individually preserved in 10 percent Formalin and transported to the laboratory where ichthyoplankton are sorted, identified to the lowest possible taxon (llogue et al. 19 76), coun ted,
and measured (larvae only) to the nearest mm total length.
1.FC: CTS:VRC 3/7/80 Prepared by Lee Graser and Carl Swor 1
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