ML19093B072
| ML19093B072 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/17/1978 |
| From: | Stallings C Virginia Electric & Power Co (VEPCO) |
| To: | Case E, Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| Download: ML19093B072 (16) | |
Text
VIRGINIA ELEOTR.IO A.ND POWER COMPANY RIOHMOND,VIRGINIA 23261 April 17, 1978 Mr. Edson G. Case; Acting Director Serial No. 21:!
Office of-Nuclear Reactor.Regulation LQA/ JEE: j al Attn: Mr. A. Schwencer, Chief Operating Reactors Branch #1 Docket Nos. 50-280 Division of Operating Reactors 50-281
- u. s. Nuclear Regulatory Commission Washington, DC 20555 License Nos. DPR-32 DPR-37
Dear Mr. Case:
Vepco is pleased to provide the attached responses to your.request for additional information dated March 16, 1978 * . This submittal contains a program description for monitoring fish popu-lations in the James River near the Surry Power Station. We hope this will provide a basis for an acceptable resolution to our Technical Specification change request dated May 16, 1977.
Very truly yours,
~. m.vfl~a;/~-Y C. M. Stallings Vice President-Power Supply and Production Operations
Enclosures:
- 1. Answers to request for additional information of March 16, 1978
- 2. Eighteen-.MonthEvaluation of theRistroph Traveling Fish Screens
~I ANSWERS TO REQUEST FOR ADDITIONAL INFORMATION OF MARCH 19, 1977
. l .. Proposal t.
V As previously demonstrated, an environmental monitoring program has been underway since prior to 1970. This program has been conducted not only by V~pco personnel but personnel from the Vi_rginia Institute of Marine Science and includes at least two years of preoperational data and about five years of postoperational data. Since no adverse environmental effects have been demonstrated to date (Vepco, 316(a) Demonstration submitted A_ugust 31, 1977:
favorable decision February 1, 1978) the Virginia Electric and Power Company hereby maintains that a reduced-effort impingement s~mpling program would be appropriate for continued monitorin~ of fish populations in the James River.
PROPOSED PROGRAM A low-level screen monitoring program consisting of one impingement sample per week (two duplicate five-minute samples) shall be conducted . . Samples will .preferably be taken on Tue~days, Wednesdays, or Thursdays.
- 2. Basis Diversity indices have become a useful tool for examining trends in biol?gical community structures. A monthly ~8d seasonal comparison.of seine, trawl and screen data from May 1974 - June 1975 (Figure l and 2), indicates that the number of speci~s and diversities are, in fact, higher from screen samples than from those taken by seine, trawl or the combination of seine and trawl samples. Table 1 shows a list of species taken only by the screens *compared to those taken only by seine and trawl, indicating the effectiveness of the screen sampling method. All other species were common to all three gear types.
Since May l, 1974, when the Ristroph screens were declared to be operational, 77 species of fishes representing 37 families were collected during
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daily sampling.
- e Since Ristroph screens return 93+% of the fishes back to the J~mes River unharmed, *(White and Brehmer, 1976), Vepco proposes, in lieu of absolute numbers being used to determine the need for additional monitoring, that a fixed percent survival rate be utilized. . ....
The average survival rate in 1977 increased to 97. l percent. This successful survival rate, coupled with the diversity and number of ~pecies taken from the screens, prove their success as a val id biological sampling gear. If the survival rate falls below 75%, Vepco will initiate a sampling program which would consist of two duplicate f1ve-minute samples daily until the survival rate once again exceeds 75%. A data analysis would determine the species responsible for the reduced survival and further analysis would attempt to assess the biological significance of the incident.
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REFERENCES Whrte, Jr., J. C. and JJ. L. Brehmer, 1976, Eighteen-Month Evaluation of the Ristroph Traveling Fish Screens, Third National Workshop on Entrainment and lmpi_ngement," PP. 367-380, New Yo_rk, NevJ York.
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FIGURE 1: NUMBER OF SPECIES AND DIVERSITIES, SURRY ....
"POWER STATION, MAY 1974 - JUNE 1975 '
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TABLE 1: SPEC I ES LI ST OF FI SHES TAKEN ONLY FROM SCREEtJS COMPARED TO FI SHES TAKEN ONLY FROM SEINE OR TRAWL (AUGHT CN XREFNS ONr...Y: CAUGHT IN SEINE ONLY:. CAUGHT IN TRAWL ONLY:
Sc0'1BERQ'10RUS MACULATUS GP."'lBU S I A J\FF I NI S LJROPHYCIS REGIUS ALOSA MEDIOCRIS MrcROPTERUS DOLOMIEUI fJMIA CAf..VA NOTROP IS J.NALOSTANUS BAIRDIELI.A CHRYSURA NOTROPIS CORNUTUS (ARANX HIPPOS (YNOSCION NEBULOSUS e
FUNDUWS MAJALIS GASTEROSTEUS ACULEATUS GOBIOSOMA GINSBURG! .
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MJRONE SAXATILIS PEPRILUS ALEPIDOTUS PETROMYlON MARINUS Pav~T0l1JS SALTATRIX SALM) GAIRDNERI SEJVDTIWS ATRO.,'!ACULATUS SYMPH.JRUS PL.AG !USA TRICHIURUS LEPTURUS
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February 24, 1976
Ecological Analysts, Inc.
Melville, New York Electric Power Research lnstitu!e Palo Alto, California New York Power Pool Scheneclady, New York PUBLISHED BY:
THE COMMUNICATIONS DIVISION OF ~
ECOLOGICAL ANALYSTS, INC. .// - ,_
275 BROAD HOLLOW ROAD *, ,....g MELVILLE, NEW YORK 11746 c,~7~~2~*;;y_;if:s.~1~~r~~-~~:'I~~:*'.:~~:: ~*~~~~~-*-;:~:~*;~~0~~~!*~~'?:; ~:'.~f,~27~~~~:'.~~;T\;:_.~.r.~~z**~~~~:~:~: ~~;': ,.
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Eighteen-Month Evaluation of tho Ristroph Traveling Fish Screens John C. White, Jr., and Morris L. Brehmer Environmental Services Department Virginia Electric and Power Company Richmond, Virginia 23261 INTRODUCTION On May 1, 1974, a new concept in vertical traveling screens for power station e
intakes was declared to be in commercial operation at th.e Virginia Electric and Power Company (VEPCO) Surry Power Station. The new screens include basic modifications to and departures from the design and operation of conventional traveling screens, changes specifically designed to protect fish that might become impinged on the screens during the cooling water withdrawal phase of power generation.
This paper will describe the modified screens and will give an assess~enf of their performance during the first 18 months of operation. The screens, manu-
. factured by Envirex Inc., are popularly known a~ the Ristroph traveling fish screens, s0 named for their basic designer Mr. J.D. Ristroph, retired Executive Manager of VEP90's Environmental Services Department.
SITE DESCRIPTION The Surry Power Station is located on Gravel Neck peninsula adjacent to Hog e
Island on the james River, Virginia, about 25 nautical miles upstream from the confluence of the river with Chesapeake Bay (Figure 1). The station consists of twin nuclear units (Westinghouse pressurized water reactors), e:ich rated at
.* 788 MWe, Cooling water is withdrawn from the James River on the down-stream side of the peninsula through a shoreline intake structure by eight
- pumps, each rated at 220,000 gal/min (13.88 m3/sec). The wate~'is pumped into a 1.7-mile* (2.74 km) long elevated concrete-lined canal, whcte it flows by
! *gravity through the condensers of both units, and is then discharged at a velocity of 6 ft/sec (I .8 m/sec) on the upstream side of the peninsula.
367 f' f '
- JGH
- Third N"tionul Work~llop on Entruinrnont nnd lmplnoomont White ond Brehmer: Rlstroph Trovoling Fish Screens .-369 SCREEN DEVELOPMENT HISTORY Developers of the Ristroph traveling fish screens were faced with a retrofit
-N- situation. The Surry intake structure that houses the eight circulating water I pumps had been in use since shortly before unit 1 became commercial on December 22, 1972. The structure, 198 ft (60.35 m) in length with eight fore-bays, had trash bars but no screens, although it had been originalJy constructed rLOOO with slots to receive conventional traveling screens.
(9b The necessity for screens outboard of the pumps had become evident when e:ns relatively large numbers of juvenile fish were found in the high-level canal. These J\
fish were being removed from the canal by eight conventional traveling localed at a second intake structure immediately in front of the conc,lcnser water boxes. I3ecause installation of cenvcn tional screens outboard of the pumps would not reduce impingement mortality levels below those cncounti:rct! at the
~
high-level screens in the canal, a decision was made to attempt to d.csig,'1 a ni:w
_traveling screen that would accomplish the following:
RRY POWER SHTION _ 1. Permit the maximum possible fish survival by providing safe removal of
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}COO l'O*CII fish from the screens and transport back to the river.
- 2. Permit installation in the existing intake structure without major modifi-cations to the structure.
- 3. Permit operation in a manner that would not jeopardize the cooling water supply to the condensers.
With these objectives as guides, the screens were designed and engineered by -
biologists and engineers who were willing to sit in open discussion sessions where each listened and learned from the other.
figure 1. Location of the Surry Power Station near Hog Isl:md on the James River, Virginia. RISTROPH TRAVELING FISH SCREEN DESCRf PTfON e
The Ristroph traveling fish screens (Figure 2) in operation at the Surry Power Station incorporate significant departures from th~ design llnd oper.ition of conventional vertical traveling screens. We believe that m:iny, if not all, or thcsi:
TI1e tidal James River estuary in the vicinity of the station can be classed as departures, which were brought about by a conceptual change in thinking from ofaol::.iline, although salinities in the range of 14 ppt have been mcas~1rcd during engineering for the removal of debris to enginceri1g for the survival and subse-cx~rcmc drouci1t conditions. Because of this wide range of salinities, freshwater, quent transport of fish, arc necessary for tbe successful operation of vcrtic~I
- estuarine, and oceanic species of fish arc found in the tidal segment that traveling f1sh screens. Major design ch:mges are shown in Table 1.
encompasses I loo0 Point at some or all times of the year. .
- Each Ristroph traveling fish screen, as engineered for the Surry Power Station The James River estuary ir, this area has extensive shallow water zones, 1s iritakcs, contains 47 screen panels each 14 ft (4.27 111) wide by 2 ft (0.6 m) high, about J miks ,vie.le, and has :i 1mintuined shipping channel along its main course. with a screen mesh size of 3/8 in. (0.45 cm). G!Jerution is continuous at a speed of 10 ft/min (3.05 m/min), with an alterrpte capability ot 20 ft/min (6.l m/min). *
- I 370 Third Natiomil Workshop on Entrninment ond Impingement I: White and Brehmer: Rlstroph Trovclinu Fish Scrct!ns, ,,.. 3 I
i Table I A Comparison of :t Typical Convcn tional Traveling Screen wit 11, the Ristroph Travcli ng Fish Screen **
II I
Conventional Screen Ristroph Screen i
l Pressure uifferentbJ operation (increases impingement time).
Continuous operation (decreases impingement time).
II Ledge between each screen Trough con!Jining 2 in. of water I panel (fish out of water during between each screen pand (fish I screen elevation). remain in w:!lcr during ser~cn . .
II panel elevation). ..
II Screen washwa ter pressure Screen wusltwater pressure 80-120 lb/in. 2 (may dcscalc 15-20 lb/in. 2 (prevents or otherwise injure fish), descaling anu injury).
I I
I Washwatcr trough or llumc Washwater trough maintains empty (except during screen 2 in. of water (fish gently iI operation). washed into water).
C::ollection basket at end of . Fish\\".JY with continuous water
\ washwatcr trough (results in supply (returns fish to river).
i dead end for fish).
- .* I I
I
. J_,_ __ ..,_ __
Screen panels are washed on the back side of the screen structure by wate sprayed from two header pipes, one inside the rotating screen and anothe
~ocated outside the screen and above a co!Jcction trough, after each rotated over the top of the head sprocket. The inside header pipe con,u. 1s 24 individual spray nozzles, while the. outside header pipe contains 48 sprays.
.! ha Colkctively, the nozzles are designed to supply approximately 200 gal/min (0.76 m3/min) of wash water at J 5-20 lb/in.2 to each of the eight screens.
Fish that become impinged remain on the face of a screen panel for a rmxi-S!DE ELEVATION FISH SCREEN mum of 2 minutes or until that panel clears the air-water interface. It is at this point in the cycle that significant mortality occurs on operating conventional screens, because fish can 11ip back into the wa\cr and be rcimpingcd rcpcati:Jly until in a moribund condition. The Ristroph screen employs a trough of water 2 in. (5.08 cm) deep by 5.5 in. (13.97 cm) wide that runs the full width of the screen along the base of each panel (Fig,ure 2). Wltcn each panel clears the air-water interface, fish drop into the trough and remain in -water until the pmcl passes ovc.r the top of the sprocket. As the p,11cl goes from vertically upwar<l Figure 2. Schematic dfogr:im of the !Ustroph traveling fish sere.en.
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372 Third National Workshop on Entrainment and lmpin.!Jcment White and Brehmer: Ristroph Traveling Fish Screen~
travel to horizontal, fish arc out of the water for a few seconds, slide down the panel as it becomes vcrtic:.il going downward, and are gently washed into a. Table 2 Percentage Alive, Number of Species, and Percentage ofT~tal Number Cau"ht b:ickside fiberglass fish sluice trough designed to maintain a water dcpthof 2 in.
for Fishes Taken May 1, 1974 to October 31, 1975 ° (5.08 cm).
The fish return system is an open top U-shaped fiberglass trough that Number Pcrccn tage of contains about 2 ft (60.96 cm) of water into which screen wash water from each Pcrccn tagc Alive of Species Total Sampled fish sluice trou;h and augmentation water flow to carry fish.and other collected material b:ick to the river to a point of discharge about 1,000 ft (304.8 m) 0.0 1 < 1.0 downstream from the screens und about 300 ft (91.4 in) offshore. The trough is 50.0-59.9 1 < 1.0 60.0-69.9 4 < 1.0 fitted with a Y-shaped section that contains a tlop gate whereby the en lire wash-water volume of about 2,500 gal/min (9.46 m3/min) can be diverted into a 17 ,000-gal (64.3 m3) fiberglass holding pool for sampling purposes.
80.0-89.9 90.0-99.9 100.0 6
20 26 87._
11.3 1.0 SAMPLING METHODOLOGY Two consecutive samples for impinged fish arc taken Monday through Friday and 12.1 ppt during these 18 months. By use of the American Fisheries Soci each week. Each sampling consists of diverting the entire screen wash water vol- gencrat guide to fish distribution "(American Fisheries Society 1970), "Atlant ume from the !lume into a fiberglass pool 28 x 20 x 4 ft (8.5 x 6.1 x 1.2 m) for freshwater" species were the most numerous in the area and constituted m a 5-minutc interval. Filling of the pool is followed by a 10-15 minute "quiet" than 70% of the total number taken (Table 3). The overall percentage of survi
?Criod, duri~s which time the level of the sometimes highly turbid James River for "freshwater" species was slightly higher than the survival of "Ati:J.ntic" a water in the pcol is slowly 1*.:wc~ed. i\s soon as fish become vis:ble, tl:cy are dip- "Atlantic-freshwater" species (Table 3). The impinged fish species compositi nettcc.l and determined to be either alive or dead. All spccim*ens of each species reflects the partial function of this section of the James River as a pat!iway arc then measured and classified into 20-mm total length (TL) ranges. Dead fish anadromous species and a low salinity area for estuary-dependent spcci 2.rc bulk weighed to the nearest 0.1 g. The family Clupeidae, represented by seven species, accounted for 58.1 %
the total number of fish *sampled (Table 4). Of these seven species, six ,
RESULTS AND DISCUSSION e
_d_esignated as "Atbntic-~~eshwater," while the_ seventh (Brcvoortia tyra,m?ts, des_ignated as "~tlantic. ". Because B. tyrannus constituted :ibou t total for the family Clupe1dac and almost 17% of the total for all fish taken, a of t From May 1, 1974 through October 31, 1975, 58 species of fish, which due to the fact that juveniles of th.is species show an obvious Iow-s:ilini represented 27 families, were collected from the Ri.stroph screens during daily distribution in this and other areas (Mansueti and Hardy 1967), considerati sampling. The average survival of all species of fish for the first 18 months of should be given to reclassifying the designation for this species to "Atlant.
operation was 93.3%. Lengths of fish collected by the screens generally ranged freshwater" or even a new "Atlantic-estuarine';-cfassific:ition for ail.species th from 30 to 200 mm TL, with occ:1sional exceptions on either side of this range. live part of their life cycles at salinities between 0.5 and 20.0 ppt.
An analysis of the number of species and percentage of survival shows that The family Sciaenidac, represented by fiyc species, accounted for 18.l %
t11e majority of the species (52 of 53) had more than 80.0% survival, with the the total number of flsh sampled (Table 4). Of these five, Lciostomus xanilwr majority of these species h~ving a survival in excess of 90.0% (Table 2). More and Micropogo~z undulatus comprised 99 .5% of the total sciaenids take th:m 99 .0% of the total number of fish sampled had more th:m 80.0% s1.uvival, Survival of fish by family was very high (Table 4). I11dividual species with with 87.6% or tl.w total number falling f:Jclwcen 90.0% and 99.9% (Table 2). multispecics families showed a wi<lcr survival range, although survival rates J The oligohdtnc zone of an estr~.ry s:1d1 as that of the James River can be than 80% were generally caused by low number,s of in<livii.luals of a given sped
,;.;;~ expected to support a wic.lc Yariety Jf fish ,;pccics. Salinities ranged between 0.0 (Table 5). Two related species, Cynoscion 11cllulo.1*11s and Ci*noscion rt"r.lis Ji;
- ~' ' *1
374 Third National Workshop on Entrainment and Impingement White and Brehmer: RistrtJph Traveling Fish Screens '37.
Table 5 Table 3 Impinged Fish by Family and Species, Showing PeFcentage Aliye and Distribution of Fishes in the Surry Area by American Fisheries Percentage of Total Taken within F:uhily Society (AFS) Designation Percentage of Tota!
Average Family Species Pcrccn tage Survival within r~mily Number Percentage Perccn !age of AfS Designation of Species Survival 18-Month Total Clupeidae, herrings Doroso11za petenense 93.6
- 44.9 Atlantic 13 94.3 19.1 Brevoortia tyrannus 94.9 29.3 Atlantic-freshwater 26 92.3 70.1 Alosa aestil'a/is 90.4 14.0 Freshwater 19 98.1 10.8 Alosa pseudolzarengus Dorosoma cepedianum Alosa sapidissima 90.7 93.1 93.5 D
l.2 Alosa mediocris 82.3 < 1.0 Table 4 Major Families Represented, Showing Percentage Survival by Pamily, Range of Sciacnidae, drums Survival within a Family, and Percentage of the Total Fish Taken Leiosto11111s xanthurus 96.7 76.6 Represented by Each Family Micropogon undulatus 82.7 23.0 Cynoscion regalis 59.2 <J.O Bairdiella clzrysura 100.0 <1.0 Pcrcen tagc of Percentage of Percentage of Cynoscion nebulosus 60.0 <LO F*amily 0 Species Survival Survival Range 18-Mon th Total Engraulidae, anchovies C!upciclac 7 93.3 82.3-94.3 58.1 Anchoa mitclzilli *32,0 100.0 Sriaenid:ic 5 93.4 59.2-100.0 18.1 Engraulidac 1 82.0 6.6 Ictaluridac, freshwater catfishes lct:1luridae 3 98.6 96.8-99.2 5.5 I ctalurus carus 99.2 54.3
- Cyprinidae 5 96.8 92.9-100.0 4.2 lctalums punctatus 98.8 28.9 Athcrinidae 3 91.7 81.7-94.6 1.9 lcralums nebu/osus 96.8 16.8 Pcrcich thyiclae 2 99.4 99.4-100.0 1.5 AnguilLidJc 1 98.9 1.0 Cyprinidac, minnows ancl carps Ccntrarchid:11; 7 99.5 99.5-100.0 < 1.0 Notropis lwdsonitts 96.6 87.0 Gubiidac 2 99.7 99.7-100.0 < 1.0 Norem(r;o1111s crysoleucas 100.0 9.9 Cyprinodontiuac 5 100.0 < 1.0 Cyprinus carpio 92.9 2.2 Percidac 2 100.0 < 1.0 Ilybognatlws nuclzalis 100.0 <1.0 Semoti/us atromaculatus l,QO.O <1.0
{a) Tiwre aw 15 acldition::1 families, each rcpn:scnted by one species, each species representing kss than 1.0% of the 18-month total. Survival range is 0.0% to 100.0%. Atherinidae, silversiclcs Mc11hlia 111c11idia , 94.0 72.9 Me111bras 111artinica :, 81.7 18.S Mcnidia beryllina '94.6 8.3 r'crcichthyiclac, h:mpcratc basses Marone americana 99.4 99.7 Marone saxatilis 100.0 < 1.0
3/1; Third N.11 iorH1I Wm kslwp on Entrulnmunt ond lmplnoumunt Whlto and Brohrnor: Rlstroph Trovollnu f'i~h Scruons 37" Table 5 (Continued)
Table 5 (Continued)
Perccn tage of Total family Species Percentage Survival within Family Percentage ofTol:11 Family Species Pcrcen tage Survival within Family Anguillidae, freshwater eels Carangidae, jacks and pompanos A11gui!la rostrata 98.9 100.0 Caranx hippos 85.7 100.0 Centrnrchidac, suniishcs Lutjanidae, snappers Lcpomis gibboms 99.5 91.4 Lutjanus griseus 100.0 100.0 Lepomis macrochints 100.0 3.5 E11neacan thus gloriosus 100.0 3.1 Pctromy:i:ontidae, lampreys l.epomis auritus 100.0 <J..O Petromyzon marinus 100.0 100.0 Pomoxis nigromaculatus 100.0 <1.0 Lepomis sp. 100.0 <LO Mugilit!ac, mulkts Ccntrarc/111s macropterus 100.0 <LO Mugifcephalus 100.0 100.0 Gobiidac, gobies Cynoglossidac, tongu~fishes Gobiosoma bosci 99.J 97.4 Symphunis plagiusa 66.7 100.0 Gobiosoma gi11sburgi 100.0 2.6 Stromatcidac, butterfishcs Cyprinodon tidae, killiflshes Peprilus alepidotus 66.7 100.0 Funilul:is hi*teroclitus 100.0 71.0 Fcmd!llus dicphamcs 100.0 16.0 Gasterostcidac, sticklebacks Cypri1:0Jo11 variegatus 100.0 11.7 Gasterosteus aculeatus 100.6 100.0 flmc!ulics 111aja/is 100.0 <1.0 Fundulus conflue11t11s 100.0 <1.0 Elopidac, tarpons Elops saurus 100.0 100.0 Pcrcidac, perches Perea J7aresce11 s Etlreostoma olmstedi So!ciclac, soks Tri11ec1es maculatlls 100.0 100.0 96.5 50.0 50.0 100.0 I
I Trichiuridae, cutlasslishcs Trichiurus lept11rus Salmonidac, trouts 0.0 10-Salmo gairdneri 100.0 100.0 Pomotomidac, b:ucfishcs II r Pomo tom/Cs saltatrix 85.3 100.0 I
. [
I3olhidac, leftcyc Jloundcrs Para!ichthys dentatus 97.2 100.0
~
Amildae, bowlins I \
Amia call'a 100.0 100.0 I I
Scombridac, ma::i:crcls and tunas I Scombero111orus maculallls 64.7 100.0 1'
- i~~
II
378 Third National Workshop on Entrainment and Impingement White and Brehmer: Ristroph Traveling Screens i
I similar survivals of about 60%, but each constituted less than 1.0% of the total I AVERAGE PERCENT NUMBER OF RELATIVE NUMBER
- 1 sciaenid population: The only species that showed 0.0% survival (Triclziurus SURVIVAL SPECIES QF FISH 00 CO '.O CD . N N (>I <.,,1 lepturus) w:is represented by one individual. Qu,Qu, Qu,Qu, -N<,J.t>u,0>-JC!)\!l Because the Surry Power Station is located in the "salinity gradient zone" of
- the James River estuary, the annual species combinations that arc encountered arc diverse. Survival rates vary both within genera an<l between genera within families (Tai.Jic 5).
During the first months of sampling the Ristroph traveling fish screens, it was
determined that minor modifications to the original design might result in better I
survival of impinged fishes. An auxiliary header wash system was installed out-side of the screens to aid in the removal of fish resting on the ledge created by the bottom side of the screen bucket traveling downward. An .iugmentation water supply system was installed at the end of each fish sluice trough to aid in the m9vcmcnt o.f fish to the river return trough. A neoprene-nylon flap was installed along the edge of the fish sluice trough to keep fish from falling
)>
VI 0
between the screen and the trough. Finally, a system was ins tailed to slow the z
,vater velocity into the sampling pool. The results were evident, because, begin-ning in August 1974, with one exception, monthly survivals have been in excess 0 of 90% (Fi 6ure 3).
- Tne number of species shows some seasonality, as manifested by a decrease in C.
J:ir.uary, February, and M:irch, followed by a sharp increase in April (Figure 3).
Several of the species, !10*,vcver, can be classified as "occasional." especially some of the oce:inic species that may be at the upriver Hmit of their range. In addition, the James River basin has been subjected to record and near-record floods in rcc*~nt years and to springtime fish "kills." Any or all of these variables l>
may lwve a.ri influence on any apparent seasonality. It is interesting to note, however, that the number of species has remained relatively constant over time.
The largest number of impinged fish usually occurs <luring the winter months. .[
111is occurrence is due, in part, to juvenile anadromous species moving seaward I I C.
and fall and winter spawned oceanic species moving into low-salinity areas. The increase L, numbers in the winter of 1974-75 was also due mainly to an C.
"explosion" of the thread fin shad (Dorosoma petenense) population in the James PJver. Prior to 1973, this species was seldom taken in this part of the l>
\
river.
. VI There appeared to be more fish in the river in the summer of 1975 than in previous years (Figure 3). The reasons for the apparent increase await further
...
- 0 analysis of aV2ifable data; however, it is possible that fish populations are in a "recovery" phase after the p:issage of f1ooclwatcrs associated with Hurricanes Agnes and Camille and m:1jor nonpower station-related fish "kills" in 1971, Pigurc 3. Relative number of fish, number of spcci;i~* il!Hl nvcraec pcrccnta{!c of 1973, and 1974. survival by month for the Ristroph trawli1t fish scr~cn system at the Surry Pow~r Stali(\il,
.~" : .
380 Thirrl Nntional Workshop on Entrainment and Impingement,._
CONCLUSIONS TI1e first 18 months of operation of the Ristroph traveling fish !iCreens at VEPCO's Surry Power Station have shown that an average of 93.3% of all impinged fish survive the impingement process. This consistently high survival rate alone serves to prove the success of the principles that have been incorpora-ted into the design of the screens.
ACKNOWLEDGMENTS In an assessment of this kind, many individuals make significant contribu-tions. TI1e authors especially acknowledge the VEPCO Surry biological staff for their diligent efforts in data collection: Messrs. J.W. Bolin, III, D.G. Kreter, W.C. Singletary, Jr., and W.J. Sweeney, II. Also, the VEPCO system laboratoiy staff, under the direction of Mr. R.A. Hammond, augrne.nted the efforts of the Surry sta.ff.
TI1e graphics were expertly prepared by Mr. H.L. Plum, and the data were assembled into workable form by Mr. N.H. Wooding, Jr. Miss Althea D. Brown typed the maauscript. -
Finally, the development of this screen and its subsequent installation was measurably enhanced by the encouragement, understanding, and recommenda-tions of Messrs. J.D. Ristroph and S.C. Brown, Jr., both engineers by profession who developed excellent insights into ecologic problems.
- BIBLIOGRAPHY American Fisheries Society. 1970. A List of Common and Scientific Names/ of )
Fishes from the United States and*Ca.:nada. 3rd Ed., Special Publication N u ~
ber 6, American Fisheries Society, Washington, D.C.
Mansueti, A.J., and J.D. Hardy, Jr. 1967. Development of fishes of the Chesa-peake Bay region. An atlas of egg, larval, and juvenile stages. Part I. Natural Resources Institute, University of Maryland. 202 pp.
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