ARTHUR KILL GENERATING STATION 

DIAGNOSTIC STUDY AND POST-IMPINGEMENT 

VIABILITV SUBSTUDY REPORT. 

PKtPARED BY CONSOLIDATED EDlSON CGMPANY OF NEW YORK, INC, 

PURSUANTTO THE DECEMBER 23,1993 ORDER ON CONSENT 

IN DEC FILE NO, R2-2985-9044 

JANUARY 31,1996 
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Post-wiement viability offish collected on the descending sides of __I___ dual flow machines __ -_was

evaluated by releasing live fish that had been marked With dye into the intake bays nearthe 

face ofthe descending screen baskets. Testfish were released in quantities of50to 150 

itEdividuais at a pint approximately one foot below the water surface at thecenters of the -

entrance portals to the descending sides of the Ristroph-modified dual flow screens. Sincethe ,c,, , ____--__­

screenportal entrances were not screened, test fish were afforded the opporbitfto escape. 

Consequently, viabiity was computed on the basis ofthe numbers of fish recovered, and not 

on the quantity released. Is is believed, but not demonstrated, that unrecovered fish swam ----_ - -I - - -_i­- fiom the intakes and thusavoided impingement. __ - -

Prehinary studies demonstrated that most fish released intointake bays and subsequently 

recovered were recaptured within 30minutes following release. Accordingly, samphg 

durations were approximately 30 minutes in duration. (Since collectionswere continuous 

during these tests, fish that were collected after the 30 minute interval were added to the 

samples.) Fish recovered _--- alive were placed in five gallon holding tanks, and were examined -A

for latent effects 24 hours las; 

B. Study Results 

1. Post-ImDineement Viabilitv Results __,_^ 

‘1 

A total of 16,427 fi~”rpresentin~~~~-~ere opportunisticallycollected from one 

unmodifiedand two Ristroph-modifieddual flowtat grgesfor 24 hour post-imGgement 

~~%sessme~attheArthur Kill Generating Station fiom February 1994 through July 

1..1-W-e 4). A total of 50 species were collected on unmodifiedSCTee3Ro.-2xGs5r 

and 47 specieswere collected fiom Ristroph-modified Screen Nos.24 and 31,respectively. 

qabiity wascalculated as the percent of fish alive at the end ofthe 24 hr latent effects i

/,assessment period relative to the total number of fish collected. The 24 hour postimpingement Viability of6918 fish collected from unmodified Screen No.23, which was 

outfitted with 1/8”x lf8” mesh, averaged 15.2%. In contrast, 24 hour post-impingement 

viabity of6,472 fish collected onRistroph-modified Screen No. 24, which was outfitted with 

1/8”x1/2” mesh,averaged 78.9%, while that for 3,037fish collected fiom Ristroph-modified 

Screen No.31,which was outfitted witi-ll;i’;~~mesh,averaged 92.4%. The difference in && b 

overall post-impkgement viability between the unmodified screen and the tw- 1qNmodified dual flow screens may largely reflect the fish-saving benefits achieved with the 

modifications. The difference in post-impingement viability offish cokcted on modified 

screenNo.24 relative to tnod’fied screen No.31 is thought to reflect differences ine n 

and the relative offish collected on each machine, both of which are di&<ssed 

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i Handline/BoidinPTank Effects 

Study rdt were initially examined to determine whether handling and holding tankvoiume 

influencsd post-impingment viability. In order to assess handlingholding tank effects, the 

following criteria were used for selection of data: 

a. 250 or more individuals of a given species, summed across the three test 

screens, must have been collected,and 

b. post-impimgement viability of a species must have been less than 80% on 

either of the two Ristroph-modified dual flow screens. 

&/

The “minimum value” of250 was selected to provide ample numbers offish for comparison of 

results across the three tanksizes, The maximum value of 80% post-impingement viability 2­

was selected so that potentially substantial differencesin viability as a fbnction of tanksize 

could be detect@. Datafor by anchovy, blueback herring. and Atlantic - - _--_­hedng met the

criri-fhble 4). Holding tgnk-speeific post-impingement viability rates for these three 

species suggested that post-impingement viability was influenced by the handlingholding e 

volume (Table 5). For example, bay anchovy collected from the fish sluiceand held in the 3 vbit ,Ib 

gallon tanks I? 

,>. Q

experienced a 77.8% post-impingement viab@, while those held in 30 and 5

Bd -.- e:%%: .A” gallon tankshad a 56.3% and 42.9% viability, respectively (Table 5). Debris sluice-collected 

bay anchovy held in 5 and 30gallon tanks experienced post-impingement viabilities 

approximately 20percentage points lower than those for fish-sluice collected fish held in the 

same sizedtanks(Table 5). Similar results were observed for blueback herring and Atlantic 

hening. Accordingly, post-impingement viabilities reported in Table 4, which reflect the 

summation ofviability data across all Sizes of holding tanks, are conservatively low. Had alt 

fish been held in large-volume collection tanks and not exposed to handling, post-impingement 

viability most likely would have been higher, particularly for relatively sensitive species. 

Based on these results, data for other assessments reported herein, were selected, where 

required, to reflect similarity of handlingholding tank sizeinorder to alleviate thesebiases. 

ii. Collection Sluice-Soecific Post-Imoingement Viabilitv 

Study results were examined to determine whether post-impingement viabifity was different 

between fish collected in fish sluices relative to those collected in debris sluices. Collection

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sluice-specific post-impingement viability was evaluated by examining24 hr viability rates for 

bay anchovy, blueback herring and Atlantic herring that were held in-. -.-.*---- - Post-impingement viability ofbay anchovy collected in fish sluices ofboth ScreensNos.24 

and 31 combined,averaged 56.3%, while that for bay anchovy wllected in the debris sluices 

ofboth screens combined, averaged 39.8%(Table 6). Similar results were observed for 

blueback herring. Fish sluice-collected blueback herring post-impingement viabiity averaged 

91.PAacross the two Wroph-modified screens, while that for debris sluice collected 

blueback herring averaged 65.9% across the two screens. Although post-impingement 

36 
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F.". ~ -., ..* 
viabiililty ofAtlantic herring averaged higher for debris sluice-coUected -fish(19.4%) than for 

fish sluice-sluicecollected fish(11.I%), the overall viabilitywas relatively low. 

Examinationof opportu~stically-collectedfish, sutnmed acrossall species and all holding 

tanks, indicated that post-impingement viability was higher for fish collected in the fish sluices 

(89.1%) than for thosecollected in the debris sluices (67.5%). Although it is believed that 

exposure to the high pressure spray wash may reduce post-impingement viabiity, it is also 

possible that the reduced viabiity of fish collected in the debris sluicesmay reflect reduced 

transfer efficiency ofdead fish fromthe screen baskets. Transfer efficiency tests (discussed 

below) showed that only 39.1%of thedead fish were collected in the fish sluices, while 

69.5%of the live fish were collected in those sluices.Thisdifference may #e due to the ability 

of live fish to flop, in contrast to dead fish, which can only slide out of the screen basket. 

Overall, the results demonstrated substantial viability for debris sluice-cotlected fish, which 

suggests that these fish should be returned to the waterway in addition to those collected fiom 

the fish sluice. 

iii Bluecrab Post-ImDineementViability 

Post-imPingement viabity of 220 bluecrabs collected from unmodified screen No.23 was 

99.1%, while that for 1,029 bluecrabs collected fkom Ristroph-modified screens Nos 24 and 

31 combined,was 99.6%at the end of the 24 hour latent effects assessment period (Table 7). 

The high viability for bluecrabs on the unmodified screens suggests that Ristrophmodifications to the dual flow screens are not necessary for protection of these organisms at 

water intakes. 

2. Effects of Food Availability on Post Impingement Viabilitv _I 

J. Ai\\ ,P 

Bay anchovy collcted fiom Screen No. 24 during September 

effects of availability on post-impingement Viability. 

fish sluice that were fdpost-impingement viability at the end of the 24 hour latent effects 

period was 84.9%, while that for the 1,574 bay anchovy that were not fed was 83.5%. For 

bay anchovy collected fromthe debris sluice, the post-impingement viability of 558 fish that 

were fed during the 24 hour interval was 74.4%, while that for 439 fish that were not fed was 

64.2%(Table 8). Examination disclosedthat fish that had been fed, induding both fish that 

were alive and aswell asthosethat died during testing, did have food in the gut. Theseresults 

suggest that the availability offood was not a principle facror in post-impingement viabitity. 

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3. Effects of Screen Mesh Size on lmpineernent and PostImoineement Viabilitv 

i Minimum Size of Fish FmDineed as a Function of Screen 

As a means to assess size-selective impingement as a Ibnction of mesh size,the minimum 

length of each of the fivemost abundant species of fish collected during the September 1991 - September 1992Impingement Study aswell during the February 1994- July 1995postimpingement viabiity substudy were listed (Table 9)- Theminimumlengths of fish collected 

on the 1/41‘_x1/2” mesh ranpd-fhm 34mmzII__*_-Ic­ to 62mewchilethe fi%-l&-&-soffish

collected on the 1/8”x1/2” mesh ranned_fiamB,~5&m.The minimumlengths of ----_e I ­

-_- these five specie observed on the 1/8”x1/8” - xn~hraged fi~m-2&mm..to-6l-mm. The 

smallest fish collected on the 1/4”x1/2”mesh was 11 mm larger thanthe smallest fish 

collected from the other two meshes. This difference may reflect the approximatedifference 

in size of fish that would be subjected to entrainment with 1/4”x1/2”mesh and 1/8”x1/2” 

mesh on Arthur kill dual flow scrwns. - - -

Among the five most abundant species of fish impnged, two species, blueback __-- herring and

Athxitic h&@, may be subject to little or no entrainment impacts, regardless of the sizeme 

that &ght be used on the screens. Blueback herring collected during this study were all 

greater than 58 mm inlength, while the minimum size of the individuals observed the 1991­

1992study was 55 mm (L,MS 1993). Since these sizes are substantially larger than the 9­

smallest fish collected on the 1/4”x1/2”mesh, and none were recorded in entrainment,,a -- samples, it is unlikely that blueback herring would be subject to entrainment regardless ofthi 

size mesh applied. Minimum lengths of Atlantic herring impinged on the three mesh sizes 

were also quite similar, ranging from 33 mm to 34 mm. The size distriiution ofAtlantic 

herring collected during the September 1991 - September 1992impingement study indicated 

that more than 98% of the individuals collected were greater than 34 mm in total length (LMS 

1993). Examination ofthe entrainment data collected during October 1991-September 1992 

study indicated that Atlantic herring constituted only about 0.5% of the post-yolk sac larvae - I *- collected. Quantitiesof Atlantic herring collected on Screen Nos 23 and 24 during this study 4 

were substantially greater than those on Screen 31. If the Atlantic herring were relatively 

un‘rformly distributed across the intakes during these studies, the relatively fewer fish collected

Il 

on Screen 31 suggests that they were entrained through its 1/4”x1/2”mesh, but were 

impmged on the smaller mesh on the other two screens. The relative abundanceof Atlantic 

herring in the post-impingement viability collections &om Screen No. 31 were substantially 

lower than those from the other two screens. If Atlantic herring were relatively uniformly 

exposed to the three intakes, the reduced abundance in ScreenNo.31 collections suggests 

that theywere entrained. Accordingly, it appears that I_in order ----I----­ to minimize e-of ‘ ,/

Atlantic herring to t, the smallest-sized mesh practical might be r-qqi-:. -

The minimum lengh bay anchovy collected on the 1/4”x1/2”mesh was 46mm, while that on 

1/8”x1/2”was 23 mm, and that on 1/8”x1/8mesh was 26 mm. Although the size distribution 

of bay anchovy impinged during the 1991-1992study indicated lW/oof the fish were greater 

42 

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than33 mm, given that a bay anchovy as small as 23 mm was collected during this study 

suggests that substantial entrainment through 1/4”x1/2” mesh would be likely. Examination 

of entrainment data collected during the September 1991-1992 study indicated that bay 

anchovy contributed nearly 74% of all larval life stages of organisms collected. These results 

reflected entrainment through the 1/8”x1/8” mesh. Accordingly, in order to minimizethe 

entrainment of bay anchovy, the smallest mesh practical would appear tobe required. 

The minimumlengths of Atlantic menhaden and Atlantic silverside observed dwing the 1994 ­ 1995 study, aswell as during the 1991-1992 impiigement and entrainment study (the 

minimumhgth specimen of Atlantic menhaden impinged was18 mm; that for Adantic 

silverside was 35 mm;post-yolksac larvae of both species were present in entrainment 

samples) suggest that the 

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smallest practical mesh size would also --appear - to be required 

inorder to entreent effects on these species. -

ii &’ Post-Imoineement Viability as a Function of Fish 

’36, 

Post-impingement viability of bay anc ion of length was evaluated using data 

collectedfiom Screen No. 24 duri for this analysis was limited to 

that obtained from only Screen No. ers of bay anchovy were collected 

!?om ScreenNo.31, and collections fio -23were not used because that machine 

was not equipped with the Ristroph-type modifications. The 668 bay anchovy collected alive 

fiom Screen No.24 on August 23, 1995 were held in 300 gallon tanksfor 24 hour latent 

effects assessments. A total of 486 of the fish were collected fiom the fish sluice; 182 were 

obtainedfrom the debris sluice. Collections fiom each sluice were held separately. At the end 

of the 24 hr latent effects assessment period, all fish were measured to the nearest nm and 

recorded as to condition (alive, dead). Data were then tabulated into 10 mm length 

increments for computation of post-impingement viability as a fbnction of length category. 

(Insuficient numbers of fish were available for evaluating viability as a fiinction of smaller 

length categories (e.g. 5 mm)). Post-impingement viability of fish sluice-collected bay 

anchovy was relatively uniform across the 5 length categories eyduated, and;with no clear 

tendencies (Table 10). Viability offish in the 30-40mm length category, which was the 

shortest length category, was 20.3% while that in th 1 0 mm Category, which was the -~”--%------

largest length ~ategory~..was273~h-Post-impingem --4? viability of debris sluice-collected fish

-hi@iG.-*G-mgedfrom 50% for fish in the 30-40 mm category to 75% for fish in 

mm category. Although tenuous, these results suggest that somewhat higher 

probably occurs among larger fish. Bay anchovy collected during I the February- May 

periodsinasnaaDd1995had Dost-impingement viabilities -~- above _-­ Wh. Fish durinrin*s 

period o f j & M 5_---__-_ S 1993). HoweGer, viability of

basovy collected during summer months were lower when collections contained ’ 

substantial numbers of smaller young-of-the-year fish. 

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fish (Table 4). Weakfish post-impingement viabiity following release on the descending sides 

ofthe michines ranged fiom 2% to 73%, while that for bay anchovy ranged fiom 13%to 

18%. Although the low Viability during the tests with these species may reflect stresses 

lLssocilifed with collection on the descending sides of the machines, they might also reflect the 

added stresses asLssociated with the handling, including marking and releasing through a 2” pipe 

that the test fish incurred. 

VL Screen Face Velocitv Profile Studiesand Assessment of Benefits of FlowmDrovine Fairines on Post-ImDinPement Viability 

A. Introduction 

Velocity profiles were measured at unmodified ScreenNo.23 and the two Ristroph-modified 

dual flow screens(Nos. 24 and 3 1) at the ArthurKill Generating Station. Thepurpose of the 

profile measurementswas to determine the distribution of the velocity and direction of flow 

along the ascending and descending sides of the machines, and to apply the results in 

evaluationsof post-impingement viabiity of fish. In addition, the profile studieswere 

performedto help evaluate the benefits of flow-improving fairings on post-impingement 

viabiity of fi&-. 

B. Velocitv Study Methods and Materials 

Measurementswere made at five uniformly distributed depths along six vertical transects on 

both sides of ScreensNos.23 and 24. Although measurementswere made along six vertical 

transects on Screen No.31, because its submerged portion is only 14.5 ft in length at mean 

sea level (versus 25.5 ft for ScreensNos.23 and 24), measurementswere taken at only three 

depths. Three of the six Vertical transects were uniformly spaced in the “upstream” one-third 

of the width of the screen basket. The other three were uniformly distributed across the 

“d0~n~trea.m’~ two-thirds of the basket (Figure 15). Thisvertical transect distribution was 

designed to detect principle flow characteristicspreviously noted at the face of dual flow 

screens during flume studies (Figure 5). Measurementswere made with a Marsh-McBknq 

Model 5 11 electromagnetic2-axis water current meter, identical to that used by Fletcher 

(1994). The instrument was attached to the lower rail ofa screen basket so that the meter 

probe was positioned midway between the top and bottom rails. The basket was then rotated 

into thewater intake to the specified depth for determination of X,Yflow velocity 

components. Three readings of the X,Ycomponents of flow were made at 20 second 

intervals at each transect and depth position. These were then rduced to velocity and angular 

componentsof the flow. Resultant values were averaged vertically to generateflow vel~dy 

and angle vectors across the ascending and descending sides ofthe screens. &esults fiom 

unmd@edScreenNo. 23 and Ristroph-modified Screen~ No._x ---__XL_-_I-~-~v*--=--­ --. ___m-__l-=---- - --A-n_ __ ~ ~ - 24 were compared to evaluate ~ 

the effectiveness of the fairing device installed on the modified screen in enhancing the 

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1 

Flume-measured 

velocity profile 

the face of a 

. simulated dual 

flow water intake 

screen without a 

flow-improving 

fairing. 

Intake Forebay 

Figure 15. Horizontal placement of velocity profde measurement points 

(A through F)at the ascending and descending sides of dual 

flowscreen baskets at the Arthur Kill Generating Station. 

Source: after Fletcher 1994 

50 
addition, comparisons of results were made between Screens Nos.24 and 3 1to evaluate 

differences in intake flow velocity on the angular componentsof theflow at the face ofthe 

screens. [The calculated velocity at the face of the mesh at Screen No. 31 is approximately 

1.3 fps, while that at Screen No. 24 is 0.9fj>s (Table l)] Velocity profile measurements were 

taken during flood and ebb tides between one hour either side of high or low slack tide stage. 

Before velocity profile measurementswere made, tests were performed to determine whether 

stray electrical currents or the metallic mass of the screen would interfere with the 

electromagnetic flow meter. Electrical current intderence wasevaluated by adjustment of 

the Marsh-McBirney meter circuitry. Metallic mass interference was evaluated by substituting 

a mechanical meter for the Marsh-McBirney electromagnetic meter. 

C. Study Results 

Tests performed to determine the presence of stray electrical currents that might intdere with 

the electromagnetic water current meter demonstrated that no interference was present. 

However, tests revealed that the meter's electrical supply cable could interfere with readings. 

Adjustments were made to the placement of the cable and interference was eliminated. 

Tests performed to determine whether the metaIlic mass of the dual flow screen and 

associated materials might interfere with the electromagnetic water current meter suggested 

that interference, if any, was minimal. Mechanical meter readings were within 2%, 8.5%, and 

16.2%of the electromagnetic meter readings for Screens Nos 23,24, and 3 1,respectively 

(Table 13). 

Flow prof3e measurementsdemonstrated that velocities were generally uniform over the 

depth at each vertical transect, but with slightly lower velocities near the bottom at some 

locations (LMS 1996, Appendix A). Velocities generally decreased with increasing distance 

fiom the upstream end of the screen baskets, while approach angle generally increased with 

increasing distance fiom the upstream end of the machines (Table 14; Figures 16, 17, 18). 

Flow velocities and approach angles across the of Screen No. 23, which was not outfitted 

with a fiont-wall fairing, differed from those at Screen No. 24, which was outfitted with a 

upstreamend ofthe wc 

-.-e­ f downstream direction, while that on Screen No. 24 was generally more uniform across the -*5 +-

central part of the mesh. At 5%~ No. 3 1,because ____of-its cx shorter - *- A velocities were tbP­

,I;22{ d. \ mo-er --_ __ -~ZT-==--k-= than thejiG&acGg&$u& App ;"fi ­ betwe%%E two Gens. Overall, velocity and approach angle data (Figures 16, 17, and 181, 

suggest that the fairings did make the horizontal distribution of flow across the screen baskets 

51 
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PUMP BAY 

FOREBAY 

7 fps 2fps 

.s 

SCALE 

Figurt 16. Veiocity Vector Distribution at Arthur Kill 

Dual FlowScreen No. 23. 

source: LMsi996 

54 

0 
PUMP BAY 

0 1 fps 2fps I * 

s 

SCALE 

Figure 17. Velocity Vector Distribution at Arthur Kill 

Dual How Screen No. 24 when outfittedwith 

a Front-Wall Fairing. 

55 
0 

-

I fps 2fps 

SCALE 

Figure 18. 

PUMP BAY 

Velocity Vector Distribution at Arthur KiIl 

Dual Row Screen No.31when outfitted with 

a Front-Wall Fairing. 
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more dorm, which may have reduced, somewhat, the velocities at which fish might be 

impinged on the mesh. 

D. Effects of Flow-Imoroving FairinPs on Post-Imoineement 

Viability 

/-

Flume testing demonstratedthat semi-elliptical fairings at the headwall of dual flow screens 

could causeintake flow to be more uniformly distributed horizontally across the face of screen 

baskets(Fletcher 1994)and presumably enhance post-impingement viabiiity of fish by 

reducing the velocity of flow at which they were impinged. Accordingly, plans were made to 

evaluate whetherfairings installed onthe Arthur Kill Ristroph-modified dual flow screens 

would improve post-impingement viabiiity. The procedure for evaluating the benefitsof 

-* - fairings included collectingviability data before the fairingswere instailed for comparisonwith 

/\ ~ data collected after installation. The effects of fiirings on post-impingement viability was 

‘/6 ,x’ J “i 

expected to be most rdiy detected on species experiencinglow to moderate post-

\ pi- ”: impingement viability on screenswithout fairings, for which ample margin for improvement \ i\ w ’ 

was available. Examination of post-impingement viability data obtained prior to installation of 

the fairings in May and June 1994(Table 15)disclosed that Atlantic herring would be the 

most appropriatespeciesfor assessment. (e.g. Post-impingementviability of395 Atlantic 

herring collected fiom Screen No.24was 22.3%). All other species collected in abundance 

(e-g.>50 fish) demonstratedpost-impingement viabilities near lW/O.Accordingly, plans 

were made to compare post-impingement viability levels for Atlantic herring collected during i 

Spring 1995 (fairings in place) with Atlantic herring data collected during 1994 before the 

fbirings were installed. 

During 1995intensive sampliig beginning @ March and continuing into June produced only 

18Atlantic herring on the fairing-outfitted screens. Viability of 16Atlantic herring collected 

on ScreenNo. 24 was 12.5%, while that for the two fish caught on ScreenNo.31 was SO?!. 

In contrast, a total of 576Atlantic herring were collected on unmodified Screen No. 23 during 

the sametime interval (Table 16). Because 0-aucity of Atlantic herring in collections 

fiom the two Ristroph-modified screens3Gssmentsof 

__ t&-k-n&ts ofthe fiont-wal-fhg? -+

~~c~gpas~-im~n~ement~~~d -not _-- be performed - - ~ as - planned. CGip&&%<f

post-impingement viability-of other species collected during the same time intervals in each of 

the two years did not provide any insite into the benefit of the the fairings in enhancing postimpingement viability generally becaup their pre-fairing viability was relatively high. 

iL; 

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