ML20079H408

Forwards Pages from Design of Water Intake Structures for Fish Protection, Re Velocity Difference Across Intake & Potential for Biofouling Even in Fresh Water

ML20079H408
Person / Time
Site:	Limerick
Issue date:	12/07/1982
From:	Mccoy R INTERIOR, DEPT. OF, FISH & WILDLIFE SERVICE
To:	Brenner L Atomic Safety and Licensing Board Panel
Shared Package
ML20079H394	List: ML20079H408
References
NUDOCS 8212160316
Download: ML20079H408 (8)

Text

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'. .. , UNITED STATES s

DEPARTMENT OF THE INTERIOR "-

I FISH AND WILDLIFE SERVICE

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Suite 322 . l

% ,Y 315 South Allen Street @ 13 to .; ~

State College, PA 16801 A i.

CE:.L December 7, 1982 Mr. Lawrence Brenner Administrative Judge Atomic Safety & Licensing Board U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Judge Brenner:

I am enclosing several pages from a recent publication " Design of Water Intake Structures for Fish Protection". I have marked the sections referring to the 2:1 velocity difference across the intake and the potential for bio-fouling even in fresh water.

This is in support of testimony I gave November 22, 1982, on behalf of Del-Aware Unlimited, Inc., Philadelphia Electric Company (Limerick Generating Station Units 1 and 2), Docket No. 50-352-OL and 50-353-OL.

Even if this cannot be submitted as evidence in the hearings, I felt it may help you better understand the intake issue.

Sincerely, Richard W. McCoy Fish & Wildlife Biologist I

Enclosures 1

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9212160316 821214 PDR ADOCK 05000352 G PDR DEC 131092

' Design Of ,

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' Water \

' Intake  !

Structures

. 'For' Fish ' Protection -

. Prepared by the

' Task Committee on Fish-Ilandling Capability of Intake Stnictures I of the Committee on flydraulle Structures of the ifydraulics Division of the American Society of Civil Engineers t

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l Published by the I

Arnetican Society.of Caval Engineers

• 345 East 47th Street New York. New York 10017 (

i 129 5CR f f- NIMi I OR ORG % Int 5 1:* W All P INi ul NIHl1 Il His i

6. ine vra ivrari Jacking lerqth of the radial screeris ns in the order of 1

Li s a , g ' , ..t tr. . ; i t .s l .: 11 int 4ke s , , t ,-ti J

• I Ir" ' J 31 3 5 e e- l l is 4nly w i t s b l e n r ..-r e t'.ef e is a porGus arjite, . i t y, tt and 300 f t ( 45. 7 and 31.4 m) . O ta neter does net at er ec iatil y

. n. n i t , tu i r. , t le tr,e qu 3n t i t ,' ut ster rewirel. un t ce tanstely, t ,4 '"' "'" "9 '" # ,

i r. t 2 6 e si'-s ttst c an r < saitault de eld eJ are l i r. i t e d . Vertitst 7. Inflow velocity throu4h screen pertorations ranqes from I to 2 fpm j t e.s t -e'Is ..t te drille1 snJ testej to seterm me the cnaracteris-(0.30 to 0.tl m/ min). The to.er velocities are suttatsle f or fine

,tt of toe a a t 'er tod tr e o mi tude of the re+4 t r ed collector sys.

sand aquif ers or corrosive waters.

tew. un s test in ; pr+;r sm ma y toe trum twa to four n.nths. 8. Net open area of the perforated screen ranges from 18 to 22 percent

/ 7,+ in11v' L s1 tsissJn units ar e lin ite t to ob.aut 25.000 ;sl /nin with the Idrger percentage generally applying to larger screens.

i c I <a ._,1/ain) tyt p c.b s t. l y mut. h les> in r, cst usatle alutfers. fo Regatred beam strength is a criteria. Perforattert sizes range from

,e t j e j s r . , .- r .oter r ew t rw ent s , wide l , spited n.ul t iple uni t s are '. .083 to 0.375 in. (2.0 to 9.5 mm) wide depending on the geolo-i te nie e t ud ill mu.t t,e ornette1 to a wrw transansstcin pipe alcal characteristics of the aquifer.

Assuming typicel values of Id percent open area and an inflow velo-to t rir i I v.t 3.

city of I f an (0. 30 m/ min), the total length of laterals can t.e vr. ur n a t i a tor n .lic,ina,j ne , i p ' #

i i s t ed t.e l ow ir e t ypitil charatteristics tur a rsdist well inta6e. This int eit ii n will t e nt , a l .,e in de t er minirq t he nroer ut ma3nttude of such an 1W ? 98I #*b" --

I L (f t) = $creen Diameter Unches) inti6" for s it en inte i

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I Ite aw al s; e ity of todiviLsl (cliettcr- anits is in the 1,000 --- b- -"I

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to l'1,uu0 ,21 Nin (4 to 40 m / min) ranye, tnat c aul d 90 as high L (m) = Screen Diameter (meters)--

a s hot J5,ma pl / nin ( 100 m /lmin) ' in a very f avoratale aquifer.

"ir r i 21t J I = ells h s ,e t.een plu ed in relatively th1n aq91ters with 10. Low Cart,on steel is the usual Collector screen material. In relatively noncorrostve waters, a minimum lite of 30 years can t;e e=pected. In it~tte!.sucity'

( a i ssun sp+ In j for multtple units is typically 1,500 ft corrosive waters and where longer life is desired, statnless steel or t u l l ei t o r

( N a. ) . An array of tullettors may thus spr ead over a large dres. Other corrosion resistant material can be used.

The liswter of the caisson depen'1s un the space reqairements f or 1

Subsurface borings must be made to develop site specific design information t t.e p.a p s a n 1 <.n the tiesrsm e needed for lateral screen Jacking for afiy but a very preliminary design. If the borings indicate one or more g eritioni ',a.a l l es t r ea 2 t l y availat21e f orms are f or a 13 f t (3.96 m) ,

potential aquifers, then vertical test wells for test pumping and for ground in.ide Ini eter toni r et e taisson. A f 6 f t (4.M m) 10 is a water level observations must be drilled and a test program undertaben in the typtial site same general manner required for proving out a vertical well installatiori,

4. i.aissoris plat e1 to depths uf up to J00 f t (61 n.) f rom the surf ace are fer.ible. Wter may tie dra.n trom two or more separate MMM 9h0PMi% PW IMM a piter s it r ei.nsar y , wi th ra li s i st reens jat6ed into the aquifers

'""'I ",The presentiv recorimended small-opening pipe intake for the reduction at different elevations from inside the (ais un. f entrainment is similar to the cylindrical pipe concept discussed in Chapter S. The t yp h a t t i twier of radial collettur screens is 8 to i6 in, * ' ' "9 " '" ' " "" $'

I N 3 16 40.h tit) but slles to 4d in. (122 tm) tould t>e con-j '.1 dW e"1 f i.e J2iling loto a very hi.[h yield aquifer.

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I SCREENING l'OR ORGANISMS 138 130 W ATER INT AKE STRtJCTt!RES .

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1. The openings are much smaller, say 0.02 to 0.08 in. (0.5 to 2 m) wide, However, it could tm expected that some of the early larvae of many species would coer,areJ with 1/4 in.

3/8 tr.. . or 1/2 in. (6.4 m. 9.5 m. or 12.7 mm)  ;

be susceptible to entrainment. Further with 0.04 in. (1.0 m) slot openings, g normally used for cylindrical pipe intakes.  ! eggs or some species would also be subject to entrainment.

Field studies (11) have been conducted with profile-wire screens to deter-

2. Due to the very small openings, periodic clogging by impin9ed material Mne Nk pdential & Mn ng emainment at a pmpoW mer Mant to M or biological growth must be expected and the screen system. therefore j located on the St. Johns River in Florida, intake screens incorporating both  ;

must be designed so that operators have easy access to the screen i O.04 to 0.08 in. (1 and 2 m) mes% were tested in situ via a simulated intake unit for cleanin9 Unlike the large-opening perforated pipe inlet.

structure; an unscreened intake pipe was utilized as a control condition. The it cannot be placed in deep water or far from shore where access ,

would t , dif ficult. results of these studies indicated that entrainment of fish larvae was reduced by the profile-wire screens by more than 60 percent as compared to the unscreened 4;though t.d openings in the pipe can be punched perforations (holes or intake pipe. Only small differences in entrainment were noted between the 0.04 s ts or profile wire. the profile wire is the favored screening eedium and and 0.08 in. (1 and Z e ) mesh screens.

its use will t,e assumed in the discussion. Unlike most of the intake screen The only field study of profile-wire screens for possible application to esigns reconsnended in this test. the concept af the small-opening profile- a once through cooling water system were conducted at the J. H. Campbell Plant w re scr*en is new and relatively untested. There are no installations for on Lake Michigan (12). The study design was sistlar to that described above power plant service presently in entstence. Many field tests are presently except that mesh sizes of 0.08 and 0.37 in. (2 and 9.5 m) were tested in com-underway and have clearly indicateJ at least some measure of entrainment pa-ison to an open intake pipe. In this case. It was also concluded, based on y reduction. The comittee accordingly recommends consideration of small-opening plankton net tow data, that a profile-wire screen intake would reduce entrain-profile wire screen in light of t.ie scarcity of alternative means for reducin9 ment. However, no significant differences in entrainment were detected be-antrainment, tween either mesh size or the open pipe. Therefore. the mechanism by which

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the apparent reduction in entrainment into the screens and pipe occurred is Biological Considerations - Stological research on cylindrical. profile-wire unclear. Nevertheless a profile-wire screen intake has been installed and screens indicates that they could be relatively effective in preventing the en-is operating at the Campbell Plant. supplying water on a once-through basis }

trafnment of fish eggs and most larvae at power plants provided that the screen slot size is small (appron%4tely 0.02 to 0.04 in. (0.5 to I.0 m). that the

% a suwged kcation mer M f t W8 4 Whe. m t N h M in, (9.5 m). not the small size being considered in this section. Operational data ,

through-slot velocity is low approximately 0.5 fps (0.15 m/sec) and that a relatively hi9h velocity (1.0 fps (0.30 m/sec) or greater) cross-flow exists are not available at this writing.

Due to the small slot size. 0.02 to 0.04 in. (0.5 to 1.0 m), and slot velo- ,

to carry organisms around and away from the screen (9).

city. 0.5 fps (0.15 m/sec), entrapment or impingement of juvenile and adult In laboratory studies. Hanson et al. (10) found that entrainment of fish fishes would not be expected to occur. Therefore, the profile-wire screen e995 (striped bass) ranging in diameter from 0.07 to 0.13 in. (1.8 to 3.2 mm) alternative appears to offer a potentially effective means of reducing fish could t,e eliminated with a profile-wire screen incorporating 0.02 in. (0.5 m) slot openings. However. striped bass larvae. 4 to 20 days old, measuring Iosses.

0.2 to 0.37 in. (5.2 to 9.2 mm) were generally entrained through a 0.04 in (1 m) slot at a level exceeding 75 percent within 1 minute of release in the tist fiume. Larval tests were conducted in a static mode with no crossflow passing the screen. It was concluded that, since positive rheotants was observed tmong these early larvae. a crossflow would act to reduce entrainment to some ex- ,

tint. An ambient current could therefore help in preventing larval entrainment.

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132 WAT ER INTAKE ST Rt;Cil1RES SCREENING FOR ORGANISMS 333

1. Multiple screen untts are used. '

DECK FOR MANUAL

2. The screen units are small enoulh in size and weight to permit con-SCREEN CLE ANING l venient handling, j -

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3. The units are mounted in such a manner that they can be periodically l MULTIPLE REMOVABLE g "-g -j removed f rom the water and manually cleaned, inside and outside. It SCREEN UNITS is espected that normal operation will require a regular schedule AS REQ'D t_ ;g g O 3 of remoeal to clean off biological growth that cannot be removed by b ac 6 wa s h hg.

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( 4 Piping downstream of the screens is designed so that individual j ,

l screen units can be isolated, backwashed, or removed without affect- l j ~

ing the operation of remaining units.

The following general factors must t,e considered when designing this type PLAN of screen:

Potential for clogging, especially from biological growth. Tests to date indicate significant, but manageable, biological growth in salt HOIST 8 MONORAll q water and a lesser growth in fresh water. The performance of the TO MANUAL z AIR COMPRESSOR screan is tnus site related. There is a significant difference in CLEANING AREA 8 ACCUMULATOR 53 the degree of biological fouling on various materldls available for fabricating the screens. Stainless steel is the standard WATER BACKWASH ~L_

material used for profile wire '.reens. Some alternative materials (OPTIONAL) t PUMP

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that are more effective in discouraging biological growth and can -

AIR BACKWASH .

be successfully fabricated using standard manufacturing procedures include 10-30 copper nickel, 90-10 copper nickel, Carpenter 20 (20%

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thromium stainless steel), Ampco 8 (Aluminum bronze) and monel (13)(14). ~ b }* -

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E 0 N Periodic painting with antifouling paints has also reduced biologi.  ! SCREEN UNIT - ., 11 $4gE O cal growth in test installations. '

IN WALL GUIDES ' - -

% VALVE

2. Site of the opening required to achieve the desired results at a NN'*^N ' WJa * *

-x - : . a qiven site. Consider the size of the organism to be prevented from j

entering and use the largest opening that will produce the desired ,

I result.

Velocity of inflow. An average slot velocity of Inflow of abnut

• 3.

O.5 fps (0.15 m/sec) has been a common figure used to date, riowever, Figure V.4 CYLINDRICAL SCREEN INTAKE WITH PULTIPLE MANUALLY CLEANABtE UNITS greater or less velocities may be better suited to a particular situation.

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t IM W ATER IN TAKE STRtiCTIJRES SCREENING FOR ORGANISMS 135 t

4. Geometry of the screen to give optimum performance. The sievle I small-opening Cylindrical screen will have the same poor velocity distribution characteristics as a simil#r larger opening screen  ;

dtscussed in SECTION IV. The length should not exceed the diameter. '

and an internal projecting pipe or other internal velocity distri- l MPRESSED butor should be used.

j , VALVE REQ'D

5. Possible adverse influence of ice formation or ice collection on FOR BACKWASH l

the screen surface- WATER l]

, 6. Influence of adjacent screen units on one another, during both ' .

AIR {

normal flow and backwashing. Performance will be influenced by the direction and velocity of ambient currents at the point of water intake.

7. tiethod of t'ackwashing. As stated in SECT! ora IV for larger opening "A" BACKWASH BY AIR OVER WATER perforated pipe screens. air blast bac6 wash has been found to be effective. Air can be introduced into the lead-in pipe upstream COMPRESSED of the screen unit. Fig. V-5A or can be discharged from a multi- VALVE REQ'D ONLY ported header inside the screen unit itself. Fig. V-58. Testing FOR UNIT ISOL ATION has shown that the latter schem is more complex but more effective.

l l l If the air enters the lead-in pipe, then the screen unit must be AIR  ;, s'fa ggg09, , ie e, e isolated by valve during backwashing. This is not necessary for l g the multioorted air header. Fig. V-58. An air blast volume of 2 to -

3 times the screen unit volume. at a pressure of 100 pst AIR HEADER (690 kPa). has been found to be ef fective in installed units se si 4tudied to date. It is desirable to remove all water from the air backwash piping upstream of the screen unit just prior (9 injection of the compressed air. This can be done by first bleeding air into the piping to displace the water.

Figure V-5 TYPICAL AIR BACKWASHING METH005 Adwyntajes of th,e small-Opening Cylj_ndr,ical, Pipe _ Intake.

I. The small screen openirg can be designed to keep many entrained Source: Richards (Ref. 41) organisms from entering the water system.

2. There is no conftned channel leading to the screens, thus eliminating ,

a possible area for entrapment of swimming organisms. .

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Q 136 WATER INTAKE S TRUCTURES g SCREENING FOR ORGANISMS 137 ,

3. The approach velocity to the screen face falls off very rapidly and Recommendations for Preliminary Design of a Small-0penin g ylindrical Pipe Intake is negligible a few inches from the screen, as discussed in SECTION tv for perforated pipe intakes and indicated in Fig. IV-32. The For preliminary design purposes the following parameters may be used in addition to those general factors enumerated above; tendency for swissung organisms to impinge is thus low. ,

4.

4. Impinged organisms can be removed by backwash without these organisms Screen unit diameters for the removable type of screen being discussed leaving the water, unme the traveling screen which is cleaned here have to date been in the range of 24 to 48 in. (61.0 to 121.9 cm). Coisnercial automatic winding of profile wire screen is above the water surf ace.

presently limited to 36 in. (91.4 cm) above which manual fabrica.

5. Trash bars, trash rakes. and traveling screens are not required. This tion is required. However, the overall cost of the screen unit vs.

is an advantage from economic, operational and maintenance points of flow capacity is not greatly increased by the manual fabrication, view. The manual cleaning of the cylindrical screen units requires Handling weight for convenient removal and washdown will be a factor less skilled personnel than the maintenance of traveling screens, in size selection.

Disadvantages of the small-Open_tng_ Cylindrical Pipe intake. b. Limit the length of the screen unit to the diameter of the screen

1. The site conditions must be such that relatively deep water is close or less and extend the outflow pipe into the interior of the to shore so that a structure similar to Fig. V-4 can be used. Unlike screen about 40 percent of the screen length. This modification will the large opening perforated pipe intake discussed in Section IV. It result in a reasonably uniform inflow and will permit convenient cannot be placed at a remote offshore location inaccessible for handling for the specific type of wall. mounted screen to which periodic removal and cleaning. this discussion applies. Tests to date have shown that the 4

2. Backwash piping and valving is relatively complex for a large array maximum inflow velocity for this design will be about 125 percent of the average, j of screen units. Also, the screen and guide materials tend to be j c.

more costly than for standard screens. It is possible that these To size the pipe leading from the screen unit into the pump chamber.

5 factors will negate much of the economic advantage of the elimina- assume a maximum outlet velocity of about 5 fps (1.5 m/sec). Tests i <

tion of trash bars and traveling screens. date indicate that the flow into the screen will be uniform when this design procedure is used.

3. Intakes proposed to date for water quantities up to say 50.000 gal / min (200 m3 / min) require a large number of relatively small screen units d. The end plate of the screen unit may be either closed with a resulting in a total structure size greater than that utilizing solid plate or with additional screen material. There is conventional screens. The intake can undoubtedly be designed for evidence that air blast backwashing is more effective if the substantially larger quantities of water, but the screen units

- end plate is solid.

must be larger than any proposed to date and handling and cleaning e. Physically locate the screens to allow for at least 24 in, will be more difficult. u (61.0 cm) of head loss from the inlet system to the pump chamber.

4. The small-opening screens have not to date been proven suitable for including losses through the screen itself, the piping and the all water qualities. Until more substantial test and operational  ; volving.

This will allow for kaad loss buildup between cleaning

, data become available, preinstallation testing is recommended for . W adons.

each site. This will include biological testing. corrosion testing. . f. Determine the total area Jf the screen by assisning an opaning and the testing of the screen system as a whole, with regard to l { width based on the biological requirements and assuming a wire

) spacing of screen units to avoid interference under specific site  ; f ze from the manufacturer's catalogue. For example, a typical waterway flow Conditions. I

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e gg W AT E R INT AK E ST RUCTURES .

, SCREENING FOR ORG ANISMS 139

• profile wtre size is 0.069 in. (1.75 rn) wide on the front face.

For this w6re typical percent openings would be as follows: _

/ b N% l TABLE V-2 ,

&( ll $ !.. . . p, l ."

OPEN AREA VERSUS WIOTH OF OPENING FOR 0.069 INCH PROFILE WIRE <o be 1 l H.

W t o t h o f_ _Open_ing Perc ent of_.Open_A_rea.

0.02 in. (0.5sm) 221 0.04 in. (1.0 en) 16 ,, c...c.s

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= . + ."..

0.06 in. (1.5en) 46 .- -

0.08 in. (2.0 en) 53 8

' l! I I j ... . e. .f Provide at least one more screen unit than called for based on total -l- - }--

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9 . .. _ L. s=

1 area required. Yhts will pemit maintaining the desired flow area ,

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l with one unit out of service for backwashing or manual cleaning. .. ,, ,,,,. ,,

e t Provide suitable valving and piping to permit isolation of each

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1 unit separately for backwashing or removal. -

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h. Provide an air backwash system. l

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l. Space the screens at least twice the diameter of the screen apart , _ _

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,, , _ _ ., , ,  ! 9 i to avoid mutual interference of the flow fields approaching the . .

; ,,, .;_j  ! i screens. - - s .. t

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• B 5 Fig. V-6 15 a typical chart fo'r sizing one type of small-opening cylindri-

'l- - M M cal screen unit designed for an average inflow velocity of about 0.34 fps .. .. .

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j (0.10 m/sec). The chart also lists weights for single screen units. This g

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chart is applicable only for No. 69 profile wire. Similar charts can be ,,, ; 4;

' obtained from manufactur ers for other wire stres and screen configurations.

STANDARD SINGLE SCREEN DIMENSIONS & WEtGHTS MISCELL ANEOUS PilV5ICAL EXCLUSION CONCEPT 5 pani ssuneen *7* O'O L D L 7%.oss' enou sia 12 e4 ss Other less prantstng physical exclusion systems have been studied exten, sively and are still being investigated. Among these are the following

; 51s is la no

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a. Artificial filter beds. Fig. V-7. Engineering problems have to

#3 '80 date not been resolved for large and n.11y reliable water with. I l 24 25 2m drawals f rom such filters (15). The primary problem with artift-

, 27 29 320 cal filters is their potential for plugging and the associated m M 32 4lo difficulty of providing a reliable backwash system. There are a  ;

i M sos few reasonably successful small installations associated with 38 595 water supply withdrawals from clear water sources. , , , , ,

l Figure V-6 PROFILE WIRE SCREEN CHART i

, Courtesy of: Johnson Division UOP Inc.

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