Association of Hanford Origin Radionuclides with Columbia River Sediment

by D. E. Robertson J. J. Fix

August 1977

Prepared for the Energy Research and Development Administration under Contract EY-76-C-06-1830

Paci f ic Northwest Laborator~es

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ENERGY RZ

ASSOCIATION OF HANFORD O R I G I N RADIONUCLIDES WITH COLUMBIA RIVER SEDIMENT

D. E. Robertson J. J. F i x

August 1977

BATTELLE P a c i f i c Northwest Labora to ry Richland, Washington 99352

SUMMARY

Dur ing t h e pas t year, t he t h r e e major o b j e c t i v e s o f t h i s s tudy have been

accomplished: 1 ) measurement o f p resen t r a d i o n u c l i d e concent ra t ions i n Colum-

b i a R i ve r sediments and a d e s c r i p t i o n of t he r a t e s and mechanisms govern ing

t he decrease i n r a d i o a c t i v i t y l e v e l s i n t he r i v e r sediments between 1971 and

1976; 2 ) a c h a r a c t e r i z a t i o n o f t he a rea l and depth d i s t r i b u t i o n o f f i n e g ra in ,

s i l t y sediments i n t h e McNary Reservo i r by sub-bottom se ismic surveying; and

3 ) o b t a i n i n g deep p i s t o n cores which penet ra te t h e e n t i r e th ickness o f sed i -

ment depos i ts a t se lec ted s i t e s i n McNary Reservo i r t o p rov ide r a d i o n u c l i d e

data f o r e s t i m a t i n g the i n v e n t o r i e s o f r ad ionuc l i des i n t h e sediment depos i ts

i n t h e McNary Reservo i r .

The r e s u l t s o f these s tud ies have shown t h a t t h e s h o r t - and in te rmed ia te -

l i v e d rad ionuc l i des have now decayed t o i n s i g n i f i c a n t l e v e l s , and o n l y a few

l o n g - l i v e d rad ionuc l i des ( i - e . , 54Mn, 55Fe, 60Coy 137Cs, 1 5 2 - 1 5 4 ~ ~ 238Pu,

2 3 9 - 2 4 0 P ~ , and 2 4 'Am) a t t r a c e concent ra t ions remain b u r i e d i n t he sediment

depos i ts . The sur face sediments i n t he McNary Reservo i r c o n t a i n much lower

r a d i o n u c l i d e concent ra t ions than deeper sediments because o f t h e bu i l d -up o f

40 t o 80 cm o f f resh , r e l a t i v e l y uncontaminated new sediment depos i t s s ince

1971. The n a t u r a l l y o c c u r r i n g r a d i o n u c l i d e 4 0 K now accounts f o r over 48% o f

t h e t o t a l a c t i v i t y o f t he sur face sediments. The 137Cs, 2 3 8 P ~ , 2 3 9 - 2 4 0 P ~ ,

and 241Am concent ra t ions i n McNary Reservo i r sediments a r e t y p i c a l o f t he f a l l -

ou t "background" l e v e l s observed i n sediments c o l l ec ted u p r i v e r f rom Hanford

a t P r i e s t Rapids Dam. Deep p i s t o n cores t h a t appear t o have penet ra ted t h e

e n t i r e sediment l a y e r s i n t he McNary Reservo i r c l e a r l y show t h a t t h e deepest

sediments ( l a i d down between 1953 and 1960) c o n t a i n u l t r a low l e v e l s o f Han-

f o r d o r i g i n r ad ionuc l ides . Th is i n d i c a t e s t h a t t h e e a r l y opera t ions o f the

Hanford r e a c t o r s du r i ng peak p roduc t ion years i n t h e l a t e 1950 's and e a r l y

1960's d i d n o t i n t r oduce any unusua l l y h i gh concent ra t ions o f r ad ionuc l i des ,

as compared t o l a t e r years when more e f f e c t i v e measures were taken t o m i n i -

mize t he r a d i o n u c l i d e re leases t o t he Columbia R iver .

The sub-bottom se ismic surveys o f t h e r i v e r bottom i n t h e McNary Reser-

v o i r revea led t he presence o f f i n e s i l t y sediment depos i ts 1 t o 5 meters

t h i c k , which a r e l o c a t e d a long t he Oregon s i d e o f t he r i v e r between P o r t

K e l l e y and McNary Dam and extend f rom near t h e s h o r e l i n e t o approx imate ly

500 meters o f f t he Oregon shore. A p r e v i o u s l y undiscovered major sediment

depos i t was a l s o observed along the Washington s ide o f the r i v e r j u s t upstream

from McNary Dam. The sediment deposi ts i n mid-channel and a long most o f the

Washington s ide a re u s u a l l y o f a sandier nature and are l e s s t h i c k . Using the

p i s t o n core rad ionuc l i de data and the observed d i s t r i b u t i o n o f sediments i n

McNary Reservoir, rad ionuc l i d e i n v e n t o r i e s f o r the photon e m i t t i n g rad io - - -.

nuc l ides were est imated t o range from about 4000 cu r ies f o r 55Fe t o about 9

cu r ies f o r 54Mn. The i n v e n t o r i e s o f t he alpha emi t te rs 2 3 8 P ~ , 2 3 9 - 2 4 u P ~ , and I

241Am were est imated t o be 0.32, 6.3, and 1.5 cur ies , respec t i ve l y . 9

The f u t u r e f a t e o f t he rad ionuc l ides i n Columbia R iver sediments (assum- . =

i n g no new a d d i t i o n s ) w i l l be a cont inu ing deeper b u r i a l by r e l a t i v e l y un- t *

contaminated new sediment deposi ts . Cont inuing r a d i o a c t i v e decay w i l l reduce

the spectrum o f s i g n i f i c a n t rad ionuc l i des t o i nc lude o n l y those w i t h very long

h a l f - l i v e s , i .e . , 60Co, '37Cs, 1 5 2 - 1 5 4 E ~ , 2 3 8 P ~ , 2 3 0 - 2 4 0 P ~ , and 241Am.

INDEX

P a g e

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SUMMARY i i i

CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

H I S T O R I C A L OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . 2

PRESENT STUDY . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

. . . . . . . . . . . . . . . . . . SAMPLING AND A N A L Y T I C A L METHODS 4

. . . . . . . . . . . . . . . . . . . . . . RESULTS AND DISCUSSIONS 9

. . . . . . BACKGROUND RADIONUCLIDE CONCENTRATIONS I N SEDIMENTS 9

RADIONUCLIDE CONCENTRATIONS I N SEDIMENTS DOWNSTREAM . . . . . 9 FROM HANFORD

. . . . . . . . . . . . RADIONUCLIDE INVENTORY I N McNARY RESERVOIR 3 0

SUB-BOTTOM S E I S M I C SURVEY OF McNARY RESERVOIR BOTTOM . . . . . . . . 30

CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6

. . . . APPENDIX A . HOLOSONICS REPORT ON SUB-BOTTOM S E I S M I C SURVEYS A.1

APPENDIX B . TABULATED RADIONUCLIDE CONCENTRATIONS . . . . . . . . . B.1

FIGURES

Opera t ing H i s t o r y o f P lu ton ium Producing Reactors a t Hanford, 1944 t o 1976

Sediment Sampl i n g Locat ions, September, 1976

G r a v i t y Core Sampling i n t h e McNary Reservo i r

Deep Sediment P i s t o n Core (300 cm) Obtained Behind McNary Dam

G r a v i t y Cores - 1976

G r a v i t y Core f rom McNary Reservo i r , Wall u l a (M-A)

Typ i ca l Radionucl i d e Composit ion i n Sur face Sediments Behind McNary Dam, September 1976

Temporal V a r i a t i o n o f 60Co D i s t r i b u t i o n s i n Sediment Cores f rom McNary Reservo i r (Bouy 3 S i t e )

G r a v i t y Core f rom McNary Reservo i r , Refuge I s l a n d (M-D)

G r a v i t y Core f rom McNary Reservo i r , Refuge I s 1 and (M-C)

G r a v i t y Core f rom McNary Reservo i r , Hat Rock (M-E)

G r a v i t y Core f rom McNary Reservo i r , 1-1 12 M i 1 es Upstream f rom Dam (M-F)

G r a v i t y Core f rom The Dal l e s Dam, Rabb i t I s l a n d (D-A)

G r a v i t y Core f rom The Dal l e s Dam (D-C)

G r a v i t y Core f rom Bonnevi l l e Dam - Stevenson (B-A)

P i s t o n Core f r om McNary Reservo i r - P o r t Kel l e y (M-B)

P i s t o n Core f rom McNary Reservo i r - Hat Rock (M-E)

P i s t o n Core #1 f rom McNary Dam (M-G)

P i s t o n Core #2 f rom McNary Dam (M-G)

Est imated I n v e n t o r i e s o f Radionucl i des ( i n Cu r i es ) Assoc ia ted w i t h Sediment Deposi ts Behind McNary Dam September 1976

Sub-bottom Seismic Survey Tracks i n McNary Reservo i r

TABLES

Decrease i n Concentrat ions o f Radionuc l ides i n Sur face Sediments i n McNary Reservo i r Between 1971 and 1976

INTRODUCTION

Dur ing t h e peak years o f p lu ton ium p roduc t i on a t Hanford, thousands o f

c u r i e s o f 5 1 ~ r and one t o tens o f c u r i e s o f o t h e r in te rmed ia te -1 i v e d r a d i o -

n u c l i d e s were re leased each day from t h e Hanford r e a c t o r s t o t h e Columbia

R i ve r and t r anspo r ted downstream.' Numerous s tud ies o f t h e r a d i o n u c l i d e t r a n s

p o r t and accumulat ion processes i n t h e Columbia R i v e r were conducted d u r i n g

t h e years o f r e a c t o r opera t ions . The p r imary focus o f these s tud ies was

t o assess t h e t r a n s p o r t , b ioaccumulat ion, and a v a i l a b i l i t y t o t h e p u b l i c o f

t h e s h o r t - and i n t e r m e d i a t e - l i v e d rad ionuc l i des i n t h e Columbia R i ve r and i t s

es tuary . These rad ionuc l i des ( i . e . , 32P, 4 6 S ~ , 51Cr , 54Mn, 58Co, "Fey 60Co,

5Zn, 95Zr-95Nb, l o 6 ~ u , and 140Ba) were o f ma jo r importance i n terms o f con-

c e n t r a t i o n and p o t e n t i a l dose t o t he p u b l i c .

Immediately f o l l o w i n g d e a c t i v a t i o n i n January, 1971 o f t h e l a s t r e a c t o r

(KE) us ing once-through c o o l i n g w i t h t r e a t e d Columbia R i v e r water, an i n t e n -

s i v e s tudy o f t h e t r a n s p o r t and d e p l e t i o n o f both s h o r t - and l o n g - l i v e d r a d i o -

nuc l i des i n the r i v e r was conducted.' Th i s s tudy showed t h a t t he sediments

were t h e major r e p o s i t o r y o f Hanfo rd -o r ig in r ad ionuc l i des , and t h a t , except

f o r 55Fe, 60Co, and 1 5 2 - 1 5 4 E ~ , the sho r t - and in te rmed ia te -1 i v e d rad ionuc l i des

i n t h e sediments would now have decayed t o i n s i g n i f i c a n t amounts. The Colum-

b i a R i v e r sediments now c o n t a i n a comple te ly d i f f e r e n t spectrum o f long-1 i ved

rad ionuc l ides, i n c l u d i n g 60Co, 137Cs, 1 5 2 - 1 5 4 E ~ , and t h e t ransuranium r a d i o -

n u c l i d e s 2 3 8 P ~ , 2 3 9 - 2 4 0 P ~ and 241Am.

The p resen t document i nc l udes data ob ta ined d u r i n g 1976 which descr ibes

the decrease i n r a d i o a c t i v i t y l e v e l s i n t h e r i v e r sediments and t h e sedimenta-

t i o n processes which occur red between 1971 and 1976. Th i s s tudy a l s o inc ludes

a d d i t i o n a l new in fo rmat ion , ob ta ined by sub-bottom se ismic survey ing of t he

McNary Reservo i r r i v e r bottom, which descr ibes t h e l o c a t i o n s and depths o f

t h e f i n e g r a i n sediment depos i ts . Deep-sea p i s t o n c o r i n g techniques were

employed t o pene t ra te t h e deepest sediment depos i t s behind McNary Dam i n o rde r

t o measure f o r t h e f i r s t t ime t h e rad ionuc l i d e concent ra t ions and d i s t r i bu-

t i o n s i n t h e very deepest sediments, which were depos i ted between 1960 and

1953. The combinat ion o f these data a l l o w s an approx imat ion o f t h e t o t a l i n -

ven to r y o f r ad ionuc l i des i n t h e sediments behind McNary Dam, which has been

shown d u r i n g t h i s and e a r l i e r s t u d i e s t o be t h e major r e s e r v o i r o f r e s i d u a l

Hanford or igin radionucl ides in the Columbia River system. A1 so, comparison of the data obtained in 1976 with the 1971 data (and i n some cases 1972 and 1973 data) allows a description of the changing pattern of radionuclide d i s -

t r ibu t ions i n the sediments since shutdown of the single-pass cooling pro-

duction reactors.

HISTORICAL OVERVIEW

The discharge of reactor e f f luen t water from the Hanford reactors t o the

Columbia River began i n 1944 upon s tar t -up of the f i r s t of nine production

reactors , e ight with once-through cooling using t reated Columbia River water

(see Figure 1 ). With the deactivation of the l a s t once-through production

reactor , K E , in January, 1971, re leases of radionucl ides to the r i ve r by Han-

ford operations became r e l a t i ve ly ins ign i f ican t . The remaining reactor i n

operation, N-Reactor, i s a dual-purpose reactor producing plutonium as well

as 860 megawatts of e l ec t r i c a l power. The reactor has a closed primary cool-

ing loop, and the only radioact ivi ty entering the Columbia River from

N-Reactor i s from very small amounts of radionuclides which migrate through

a so i l bank t o the r i ve r from a low level l iquid waste disposal trench located several hundred yards from the r i ve r .

During operation of the e ight reactors w i t h once-through cool ing, t reated Columbia River water was passed through the reactors and returned t o the

Columbia River a f t e r a few hours' holding time. During passage through the

reactors , the cooling water was subjected t o the ambient neutron f lux which resulted in neutron act ivat ion of the various t race elements present in the water. In addit ion, occasional fuel element f a i l u r e s occurred and t race amounts of i r rad ia ted fuel were leached by the cooling water and carr ied in to

the Columbia River. The radionuclides discharged t o the r i ve r in reactor e f -

f l uent water included neutron act ivat ion products, f i ssion products, and

t races of transuranium radionuclides. Upon entering the Columbia River, the

radionucl ides were rapidly dispersed i n the r i ve r water, sorbed onto de t r i t u s

and inorganic par t i cu la tes , o r incorporated in to the aquatic biota. While

the t o t a l amounts of radioact iv i ty added to the r iver were ra ther large, the flow volume of the r i ve r i s enormous, and a careful monitoring program as- sured t ha t the r i ve r water radionuclide concentrations a t downstream locations

of domestic water consumption never exceeded regulation l imi t s .

E s s e n t i a l l y a l l o f t h e shor t -1 i v e d rad ionuc l i des i n t he r i v e r f rom Hanford

o r i g i n have now decayed l e a v i n g a few l o n g - l i v e d rad ionuc l i des . Much i n f o r -

mat ion p e r t a i n i n g t o t he s tud ies o f p r i m a r i l y s h o r t - l i v e d r a d i o n u c l i d e s i n t he

r i v e r i s g iven i n References 1-8.

I n 1971, s h o r t l y a f t e r shutdown o f KE r e a c t o r , sampl ing programs were

i n i t i a t e d t o s tudy t h e d i s t r i b u t i o n and d e p l e t i o n o f r ad ionuc l i des i n Columbia

R i v e r water, sediments, and b i o t a . (8 '9) As p a r t o f t h i s program, sediment

cores were c o l l e c t e d a t se lec ted 1 oca t ions behind McNary, John Day, The Da l les ,

and Bonnev i l l e Dams t o determine t he t r a n s p o r t o f r ad ionuc l i des th rough t h e

major sed imenta t ion bas ins l o c a t e d behind each dam. The l o c a t i o n s o f these

sampling s t a t i o n s a r e shown i n F igu re 2.

PRESENT STUDY

I n 1976, f und ing was p rov ided t o r epea t t h e 1971 measurements o f t h e r a d i o -

n u c l i d e concen t ra t i ons i n t h e sediments and, i n a d d i t i o n , t o map t h e a rea l and

depth d i s t r i b u t i o n o f sediments behind McNary Dam us ing sub-bottom se ismic pro-

f i l i n g techniques. The areas o f g rea tes t sediment accumulat ion were then sampled

by deep-sea p i s t o n c o r i n g techniques t o pene t ra te t h e e n t i r e sediment overburden

l a i d down s i nce t h e complet ion o f McNary Dam and t h e f i l l i n g o f t h e r e s e r v o i r

i n 1953.

Th is s tudy was in tended t o assess t he present s t a t u s o f Hanford o r i g i n

r ad ionuc l i des i n t he Columbia River , t o p rov ide a d d i t i o n a l i n f o r m a t i o n on t h e

l o n g - l i v e d rad ionuc l i des , and t o p rov ide an e s t i m a t i o n o f t h e i n v e n t o r y o f

r ad ionuc l i des deposi t e d behind McNary Dam.

SAMPLING AND ANALYTICAL METHODS

A number o f sampl ing l o c a t i o n s rang ing f rom P r i e s t Rapids Dam above t he

Hanford P r o j e c t t o Bonnev i l l e Dam, some 360 k i l ome te rs downstream f rom Hanford,

have been e s t a b l i s h e d as p r imary sampl ing s t a t i o n s (see F igu re 2 ) . These s ta -

t i o n s were se lec ted f rom areas o f known f i n e sediment accumulat ion, and t h e i r

sediments c o n t a i n a r e c o r d o f t h e r a d i o n u c l i d e d ischarges t o t he r i v e r . Because

t h e McNary Reservo i r , l oca ted approx imate ly 80 km downstream f rom t h e reac to r s ,

represen ts t he major r e p o s i t o r y o f r a d i o a c t i v e sediments, a more i n t e n s i f i e d

sampl ing e f f o r t was conducted t he re t o b e t t e r c h a r a c t e r i z e t h i s area.

ki lometers

LITTLE WHITE

ICE HARBOR

Y A K I M A R. SNAKE R.

R' WHl TE SALMON R. /KLICKITAT R. JD-A

JOHN DAY R.

McNARY DAM M-F

1. lHE DALLEs DESCHUTES R.

WALLA R.

FIGURE 2 . Sediment Sampling Loca t ions - September, 1976

To determine t h e rad ionuc l i de concent ra t ions i n sur face sediments and i n

depth p r o f i l e s down t o approximately 55 cm, a 15 cni diameter g r a v i t y co re r was

used throughout t h i s study (see F igure 3). This c o r i n g device has been used

i n prev ious s tud ies o f Columbia R iver sediments, and has been shown t o c o l l e c t

r e l a t i v e l y undisturbed, representa t i ve sediment cores.

Immediately a f t e r sampling, t h e sediment cores were capped on each end

and were f rozen i n t h e i r p l a s t i c b a r r e l 1 i n e r s . A t the l abo ra to ry t he cores

were then removed, s t i l l f rozen s o l i d , f rom the p l a s t i c core b a r r e l s and 2.5 cm

t h i c k s labs were c u t f rom t h e core by a f i n e j e t o f ho t water. The ou ts ide

cent imeter o f r a d i u s was trimmed from each s lab t o remove any poss ib le contami-

n a t i o n from o v e r l y i n g sediment which may have been t ranspor ted downward du r i ng

the c o r i n g process. The s labs were then thawed, d r i e d a t 105OC, pu lver ized ,

and then approximately 150 g a l i q u o t s were weighed and p laced i n t o 2-cm t h i c k

by 10-cm diameter p l a s t i c count ing conta iners . The concentrat ions o f gamna-

e m i t t i n g rad ionuc l i des i n t h e samples were then measured by count ing on a l a r g e

dual coincidence NaI (T I ) gamma-ray spectrometer and on a Ge(Li ) diode deJ

The transuranium rad ionuc l ides 2 3 8 P ~ , 2 3 9 - 2 4 0 P ~ and 241Am were n

i n 100 gram a l i q u o t s a t LFE Corp., Richmond, C a l i f o r n i a . The p lutonium .

americium were removed from the sediments by a c i d leaching, p u r i f i e d by r a d i o -

chemical separat ions and e lec t rodepos i ted on s t a i n l e s s s tee l d i scs . The p lutonium

and americium on the d i scs were then measured by alpha spectrometry by count ing

f o r 1000 minutes o r longer on a S i ( L i ) diode de tec to r o r i n g r idded i o n i z a t i o n

chambers. P l u t o n i um-236 and 243Am were added t o each sample as t r a c e r s i n

determin ing the chemical y i e l d through the procedure.

I n September, 1976 two personnel f rom the Oceanography Department o f t he

U n i v e r s i t y o f Washington were employed t o a s s i s t us i n o b t a i n i n g deep 5-cm

diameter sediment cores (up t o 300 cm i n l eng th ) from known h igh sedimentat ion

areas us ing deep-sea p i s t o n c o r i n g techniques. The o b j e c t i v e o f the deep c o r i n g

was t o penet ra te the e n t i r e f i n e sediment deposi ts l a i d down behind McNary Dam

s ince 1953, and thus determine the rad ionuc l i de concentrat ions i n t he very

deepest sediments which had never been measured. Four p i s t o n cores, ranging

from 218 cm t o 295 cm i n l eng th (see Figure 4 ) were obta ined a t th ree l o c a t i o n s

i n t h e McNary r e s e r v o i r : immediately behind McNary Dam (M-G), a t Hat Rock (M-E)

and a t Po r t Ke l l ey (M-B). A t the l a b o r a t o r y t he p i s t o n cores were sect ioned

FIGURE 3. Gravity Core Sampling in the McNary Reservoir

FIGURE 4. Deep Sediment P i s ton Core (300 cm) Obtained Behind McNary Dam

-8-

i n t o 10-cni 1 ong segments, and t h e sediments were d r i ed, pu l v e r i zed, packaged

and measured f o r r a d i o n u c l i d e con ten ts as descr ibed above. A t McNary Dam and

P o r t K e l l y i t appeared t h a t t he p i s t o n cores (274 cm and 234 cm long, r e s p e c t i v e l y )

had penet ra ted t he f i n e sediment depos i ts t o t he o r i g i n a l r i v e r bed. However,

a t Hat Rock, where sediment depos i ts a re es t imated t o be about 300 t o 420 cm

deep, a 295-cm long p i s t o n core d i d n o t appear t o pene t ra te t he e n t i r e t h i c k -

ness o f f i n e deposi ts .

RESULTS AND DISCUSSION

BACKGROUND RADIONUCLIDE CONCENTRATIONS I N SEDIMENTS

The 38-cm l ong g r a v i t y co re c o l l e c t e d j u s t above P r i e s t Rapids Dam serves

as a "background" sediment sample f o r comparing sediments c o l l e c t e d downstream

from Hanford, s i nce i t con ta ins o n l y f a l l o u t r ad ionuc l i des f rom weapons t e s t i n g

o r i g i n (see F igure 5). Cesium-137 i s t he most abundant f a l l o u t r a d i o n u c l i d e

p resen t i n t he P r i e s t Rapids sediments. Trace amounts o f 2 3 8 P ~ , 2 3 9 - 2 4 0 P ~ and

241Am o f fa1 l o u t o r i g i n a r e a1 so present . The 137Cs, PU and Am concent ra t ions

i n P r i e s t Rapids sediments a r e very s i m i l a r t o those observed i n sediments f rom

the McNary R e s e r ~ o i r ~ i n d i c a t i n g f a l l o u t t o be an impo r tan t source o f these

r a d i o n u c l i des i n r i v e r sediments downstream f rom Hanford. The bottom sediment

o f t h e P r i e s t Rapids core (30-38 cm) appears t o pre-date t he per iods o f maximum

f a l l o u t i n t he e a r l y 1960 's s ince t h e 137Cs, PU and Am concent ra t ions decrease

r a p i d l y t o ext remely low values below 30 cm. The lHCs maximum a t a depth of

25-28 cm apparen t l y corresponds t o sediments depos i ted i n 1961-63, t h e peak

f a l l o u t years f o r t h i s r ad ionuc l i de . Using 137Cs as a t r a c e r o f sediment depo-

s i t i o n , a sediment accumulat ion r a t e o f approx imate ly 1.8 cmlyear i s est imated,

a r a t e much lower than t he accumulat ion o f sediments i n t h e downstream McNary

Reservo i r , which rece ives h i gh suspended loads f rom the Yakima, Snake and

Wal la Wal la Rivers .

RADIONUCLIDE CONCENTRATIONS I N SEDIMENTS DOWNSTREAM FROM HANFORD

The s t r e t c h o f r i v e r between Hanford and t h e conf luence o f the Walla Walla

R i v e r (see F igure 2 ) i s f a s t moving water, and no major sedimentat ion occurs

i n t h i s s t r e t c h o f t he r i v e r . However, one smal l s a n d y - s i l t co re was obta ined

near-shore a t t h e o l d Hanford f e r r y s i t e (H-A). Cobalt-60, 54Mn and 1 5 2 - 1 5 4 E ~

of Hanford r e a c t o r o r i g i n were p resen t i n concen t ra t ions t y p i c a l l y observed i n

( l H 3 13M Atla f i l l u l ~ 'NO l lV l l lN33N03

t h e McNary Reservo i r , b u t t he p lu ton ium and americium concent ra t ions were much

lower (see F igure 5) .

A 40-cm l ong sandy-s i l t core was c o l l e c t e d a t Wal l u l a (M-A) which con ta ined

very low l e v e l s o f Hanford o r i g i n r ad ionuc l i des (see F igu re 6 ) . The r e l a t i v e l y

coarse sand depos i ts i n t h i s s t r e t c h o f t h e r i v e r a r e t y p i c a l l y cha rac te r i zed

by low l e v e l s o f adsorbed r a d i o a c t i v i t y compared t o f i ne -g ra ined sediments which

a re found severa l k i l o m t e r s downstream.

The n a t u r a l l y o c c u r r i n g gamma-emitter 4 0 K i s now t h e most abundant r a d i o -

. nuc l i de i n sur face sediments behind McNary Dam, and accounts f o r approx imate ly

48% o f t h e t o t a l r a d i o a c t i v i t y (see F igu re 7 ) . The n a t u r a l l y o c c u r r i n g 226Ra

and 228Th account f o r about 4% and 1.8%, r e s p e c t i v e l y , o f t h e t o t a l a c t i v i t y .

The major gamma-emitting rad ionuc l i des o f Hanford o r i g i n i n Columbia R i ve r

sediments a t McNary a r e now 60Co (5.27 y r ) , 137Cs (30.1 y r ) , and 1 5 2 - 1 5 4 E ~

(1 3 y r , 8.6 y r ) (see F igure 5 ) . The sho r te r -1 i v e d 65Zn, 4 6 S ~ and 54Mn, which

were i n r e l a t i v e l y h i gh concent ra t ions s h o r t l y a f t e r t he shutdown o f t h e Hanford

reac to r s , have now decayed t o ext remely low concent ra t ions . The X-ray e m i t t e r

55Fe (2.7 y r ) i s s t i l l t h e most abundant Hanford o r i g i n r a d i o n u c l i d e i n t h e sed i -

ments, b u t i s o f minor importance f rom r a d i a t i o n dose cons idera t ions . Dur ing

the n e x t decade the 55Fe concent ra t ions wi 11 become i n s i g n i f i c a n t compared t o

the above l o n g e r - l i v e d rad ionuc l i des . The decrease i n concen t ra t ions o f these

r a d i onucl i des i n t he sur face sediments behind McNary Dam between A p r i l , 1971

and August, 1976 a r e shown i n Table I.

The t r ansu ran i um alpha-emi t t i n g rad ionuc l ides 238Pu, 2 3 9 - 2 4 0 P ~ and 241Am

are p resen t i n su r face sediments i n ext remely low concent ra t ions , as shown i n

F igu re 5, and a r e t y p i c a l o f concen t ra t ions observed i n P r i e s t Rapids Dam sed i -

ments upstream from Hanford.

The sur face sediments i n t h e McNary Reservo i r now c o n t a i n t h e lowes t con-

c e n t r a t i o n s o f r ad ionuc l i des i n t h e accumulated s i l t y depos i ts . Th i s i s due t o

f resh depos i ts o f r e l a t i v e l y uncontaminated sediments which have accumulated

between 1971 and 1976. The bu i l dup o f these r e l a t i v e l y uncontaminated sediments

s i nce 1971 can be g r a p h i c a l l y seen i n F igure 8 which shows t h e depth d i s t r i b u t i o n

o f 60Co i n f o u r 6" diameter by 50 cm deep g r a v i t y cores c o l l e c t e d between A p r i l ,

1971 and August, 1976. These cores were c o l l e c t e d a t approx imate ly t h e same

l o c a t i o n , 450 meters upstream f rom McNary Dam on t he Oregon s i de o f the r i v e r .

t I NDI CATES LESS THAN DETECT1 BLE RESULT

- - - 0 6 0 ~ o McNARY RESERVOI R, WALLULA (M-A) - - 0137cs GRAVl TY CORE - - 54 815l76

M n - 152- 154Eu

- - - - - - - -

-

- - - - - - -

-

7

I 0.01 10 20 30 40 50 60 70

SEDIMENT DEPTH, CM FIGURE 6. G r a v i t y Core f r om McNary Reservo i r , Wal l u l a (M-A)

-1 2-

TABLE 1. Decrease i n Concentrat ions o f Radionucl i des i n Surface Sediments i n McNary Reservoi r Between 1971 and 1976

Typ ica l Concentrat ions i n D/M/g Dry Sediment

A p r i l , 1971 August, 1976

1100 30 (es t . )

240 0.14

120 0.34

60 2.7

5 1 2.2

25 0.32

9 2.7

0.06 0.03

CORE DEPTH (cm)

CORE COLLECTED CORE COLLECTED - APRIL 15, 1971 FEBRUARY 24, 1972

+APR I L,

-\ -

i / -

- \ \

FIGURE 8. Temporal V a r i a t i o n o f 60C0 D i s t r i b u t i o n s i n Sediment Cores f rom McNary Reservo i r (Bouy 3 S i t e )

-

- APRIL

- MAR,

1971

*' I I I

I I I I I

CORE COLLECTED - MARCH 6, 1973

- APRIL, 1971

CORE COLLECTED AUGUST 5, 1976

I n A p r i l , 1971 j u s t f o l l o w i n g the shutdown o f KE reac tor , t he h ighes t 60Co

concent ra t ions were observed i n the surface sediments, and a sub-surface peak

a t a depth o f approximately 27 cm was observed which c o r r e l a t e d w i t h an unusua l l y

h igh r i v e r r u n - o f f i n June, 1967. This h igh r u n o f f r e s u l t e d i n ex tens ive upstream - scour ing o f t h e r i v e r bottom, which re leased pre-deposited r a d i o a c t i v i t y f rom

the s t r e t c h o f r i v e r between Hanford and Richland r e s u l t i n g i n increased r a d i o -

n u c l i d e l e v e l s being t ranspor ted t o the McNary Reservoir . The core c o l l e c t e d

i n February, 1972, ten months l a t e r , shows the a d d i t i o n o f about 17 cm o f new,

less-contaminated sediment deposits; sur face concentrat ions deposi ted i n

A p r i l , 1971 showed a maximum a t 17 cm, and the 1967 maximum peak moved down t o

about 37 cm. The 1971 peak has made a g rea ter s h i f t downward compared t o t h e

1967 peak because the subsurface sediments become more compacted as a f u n c t i o n

o f depth, whereas the upper 10-15 cm o f sediment a re r e l a t i v e l y f l o c c u l e n t and

l e s s dense. The core c o l l e c t e d i n March, 1973 shows t h a t approx imate ly 27 cni o f

new, r e l a t i v e l y uncontaminated sediments have been deposi ted over t he 1971 sed i -

ments o f maximum r a d i o a c t i v i t y . From t h e August, 1976 core i t i s ev ident t h a t

t h e bu i l dup o f f r e s h sediment has now amounted t o approx imate ly 40 cm. Thus, i t

becomes obvious t h a t the f a t e o f the r a d i o a c t i v e sediments which were deposited

du r i ng the years o f r e a c t o r operat ions w i l l be a b u r i a l by new, r e l a t i v e l y uncon-

taminated sediments. This na tu ra l b u r i a l process should cont inue a t approx i -

mate ly the same r a t e unless the sediment accumulation dynamics s i g n i f i c a n t l y

change.

Two g r a v i t y cores were c o l l e c t e d i n the McNary Reservoi r a t Refuge Is land,

approximately 15 km upstream f rom McNary Dam. One core was c o l l e c t e d on the

Washington s i d e and t h e o the r d i r e c t l y across the r i v e r on t h e Oregon side. The

Hanford o r i g i n rad ionuc l i de composit ion o f the sediments f rom the Washington

s i d e was about 2 t o 3 t imes h igher compared t o sediments from the Oregon s ide

(see Figures 9 and 10). This presumably i s due t o t he g rea te r d i l u t i o n o f t he

r a d i o a c t i v i t y i n t he sediments on t h e Oregon s ide o f t h e r i v e r by t he h igher

i n f l u x o f uncontaminated sediments from the Snake and Walla Wal la Rivers. It

i s known from our pas t sediment c o r i n g experience, and r e c e n t l y v e r i f i e d by

t h e sub-bottom seismic survey (see Appendix) , t h a t t h e major sediment deposi ts

i n McNary Reservoi r occur on the Oregon s ide o f t he r i v e r and a r e of Snake and

Wal la Walla R i ve r o r i g i n .

McNARY RESERVOI R,REFUGE I SLAND (M-D) GRAVITY CORE

I t I N D I CATES LESS THAN DETECT1 BLE RESULT

0.011 1 10 20 30 40 50

SE D l MENT DEPTH, C M

FIGURE 9. Gravity Core from McNary Reservoir, Refuge Island ( M - D )

t INDICATES LESS THAN DETECT1 BLE RESULT

5 4 ~ n M c N A R Y RESERVOIR, REFUGE I S L k N D (M-C) 152- 154Eu GRAVITY CORE

O 6 0 ~ 0 815176

A137 C s

10G 6SZn

+ I C3

0.91 I I I 10 20 30 43 50 09

SE D l MENT DEPTH. C M

- 10

> rn a - m 1

E \

-a

2 0 - + Q:

1 .0 - + 5 0 Z 0 0

0 .1

FIGURE 10. Gravity Core from McNary Reservoir, Refuge Island ( M - C )

- - - - - - -

-

- - - - - -

- - - - - - -

G r a v i t y cores were a l s o c o l l e c t e d a t Ha t Rock ( S t a t i o n M-E) and approx i -

mate ly 4 km upstream f rom McNary Dam ( S t a t i o n M-F). These cores showed r a d i o -

n u c l i d e depth p r o f i l e s very s i m i l a r t o t h a t observed a t S t a t i o n M-G j u s t above

McNary Dam (See F igures 11 and 12).

Wi th the complet ion o f John Day Dam i n 1972 a r e l a t i v e l y s l a c k water

r e s e r v o i r was c rea ted which serves as a p a r t i a l r e p o s i t o r y f o r suspended sed i -

ments t r anspo r ted pas t McNary Dam. I n August, 1976 t h e f i r s t g r a v i t y co re

c o l l e c t e d behind John Day Dam ( S t a t i o n JD-A) e x h i b i t e d a r a d i o a c t i v i t y depth

p r o f i l e very s i m i l a r i n concen t ra t i on t o t h a t observed i n cores c o l l e c t e d behind

McNary Dam.

The r a d i o n u c l i d e concent ra t ions i n cores c o l l e c t e d behind t h e Da l l es Dam

( S t a t i o n s D-A, D-B and D-C) showed s l i g h t l y decreased l e v e l s compared t o sedi - ments f rom McNary Dam (see F igures 13 and 14). The g r a v i t y core c o l l e c t e d

behind Bonnevi 1 l e Dam a t Stevenson, Washington ( S t a t i o n B-A) conta ined t h e lowes t

r a d i o n u c l i d e concent ra t ions , and appeared t o be a very s l ow l y sediment ing area

(see F igure 15). Below a core depth o f 20 cm the r a d i o n u c l i d e concent ra t ions

decreased very r a p i d l y t o n e a r l y undetectab l e l e v e l s f o r a1 1 r a d i onucl ides.

I t appears t h a t sediments below a depth o f 20 cm were depos i ted be fo re t h e Hanford

opera t ions , began, and would thus represen t t he o l d e s t f i n e sediment depos i ts we

have y e t observed i n the r i v e r .

P i s t o n Cores

Using t h e Hanford o r i g i n r ad ionuc l i des as t r a c e r s o f sediment depos i t i on

ra tes , i t has been es t imated t h a t up t o 3 t o 7 meters o f sediment have accumulated

i n some areas o f t h e McNary Reservo i r . The h igh sedimentat ion areas a r e l oca ted

on the Oregon s i d e o f t he r i v e r between Wa l l u l a Gap and McNary Dam. These sed i -

ments a re ma in l y o f Snake R i v e r and Walla Walla R i ve r o r i g i n . The r a d i o n u c l i d e

concent ra t ions i n about t h e deepest t h i r d o f these sediment l a y e r s have,previous

t o t h i s t ime, never been measured and would represen t sediment depos i ted between

about 1960 and 1953. McNary Reservo i r began f i l l i n g i n 1953. Dur ing t h i s p e r i o d

a l l e i g h t o f t h e Hanford r e a c t o r s were i n opera t ion , and conceivably , radionucl ide

d ischarges t o the r i v e r du r i ng t h i s t ime would rep resen t maximum amounts. Thus,

deep-sea p i s t o n c o r i n g techniques were employed t o pene t ra te t h e e n t i r e s i l t y

sediment depos i ts a t 3 l o c a t i o n s between Wal lu la Gap and McNary Dam. A t two o f

FIGURE 11. G r a v i t y Core f rom McNary Reservo i r , Hat Rock (M-E)

- - - - 5 4 ~ n McNARY RESERVOI R, 1 112 MI LES UPSTREAM - - 6oco

FROM D A M (M-F) GRAVITY CORE

- 137cs 8/18/76

- 152-154Eu

7 - - - - - - -

-

-

- - - - - - - - -

- - - - - - - INDICATES LESS THAN DETECT1 BLE RESULT -

-

I I 0.01 10 20 30 40 50 60 70

SEDIMENT DEPTH, C M

FIGURE 12. G r a v i t y Core Froni McNary R e s e r v o i r , 1 112 M i l e s Upstream f r o m Dam (M-F)

1 INDICA lES LESS THAN DETECTIBLE RESULT

SEDIMENT DEPTH, CM

FIGURE 13. G r a v i t y Core f rom The D a l l e s Dam, Rabb i t I s l a n d (D-A)

THE DALLES DAM (D-C) GRAVITY CORE

SEDIMENT DEPTH, C M

FIGURE 14. G r a v i t y Core f rom The D a l l e s Dam (D-C)

SEDIMENT DEPTH, C M

FIGURE 15. G r a v i t y Core from Bonnevil l e Dam - Stevenson (B-A)

these l o c a t i o n s (M-B and M-G) i t appeared t h a t t h e p i s t o n cores had indeed pene-

t r a t e d these depos i ts s i nce t h e v e r y bottom o f these cores con ta ined coarser

sand and d e b r i s which would be c h a r a c t e r i s t i c o f t h e o r i g i n a l r i v e r bottom.

F igures 16, 17, 18 and 19 show the depth d i s t r i b u t i o n s o f a number o f r a d i o -

nuc l i des i n p i s t o n cores c o l l e c t e d a t these l o c a t i o n s . The c h a r a c t e r i s t i c 60Co

peaks seen i n t h e 15-cm d iameter by 50-cm deep g r a v i t y cores (compare w i t h

F igure 5 ) can e a s i l y be i d e n t i f i e d i n t he upper 100 cm o f t he McNary #2 p i s t o n

core. I n a d d i t i o n , a 60Co concen t ra t i on maxima e x i s t s a t a depth o f about 120 cm,

which corresponds t o sediment depos i ted about 1963. Th i s da te can be de r i ved

f rom t h e depth d i s t r i b u t i o n o f 137Cs, which shows a broad maxima peaking a t a

depth o f about 120 cm. A l a r g e f r a c t i o n o f t h e 137Cs i n t h e r i v e r sediments

o r i g i n a t e d f rom f a l l o u t f rom nuc lea r weapons t e s t i n g . The peak f a l l o u t year

was 1963 and t he 137Cs maxima i n t he sediments corresponds w i t h sediments depos i ted

d u r i n g t h a t pe r i od .

It i s r eassu r i ng t o no te t h a t t h e 60Co, 1 3 7 C ~ , 1 5 2 - 1 5 4 ~ ~ and t r ansu ran i c

r a d i o n u c l i d e concent ra t ions i n t he bottom 100 cm o f t h e p i s t o n cores a r e very

low. Th is i n d i c a t e s t h a t no abnormal ly h i gh d ischarges o f r ad ionuc l i des t o t h e

r i v e r from t h e Hanford r e a c t o r s occurred du r i ng t he e a r l y years o f t h e i r ope ra t i on

a t peak p lu ton ium produc t ion . These very low concent ra t ions o f r ad ionuc l i des i n

t he Columbia R i ve r sediments a r e t r u l y remarkable, cons ide r i ng t h e l a r g e quan-

t i t i e s o f r a d i o a c t i v i t y which were re leased t o t he r i v e r d u r i n g t he years o f

r e a c t o r opera t ions .

From s t u d i e s of sedimentat ion r a t e s us ing r a d i o n u c l i d e r a t i o s , and from

the observed r a p i d bu i l dup o f new sediments a t t he Hat Rock (M-E) p i s t o n c o r i n g

s i t e , i t has been es t imated t h a t t h i s l o c a t i o n i s t h e f a s t e s t sediment ing area

o f t h e r i v e r observed thus f a r . Sedimentat ion r a t e s o f 16 t o 30 cm/yr have been

es t imated f o r t h i s l o c a t i o n (sed imenta t ion r a t e s a r e v a r i a b l e f rom yea r t o yea r

and appear t o be d i r e c t l y r e l a t e d t o annual r u n o f f volumes). I t appears obvious

from the depth d i s t r i b u t i o n s o f r ad ionuc l i des i n t h e bottom p o r t i o n o f t h e

Hat Rock p i s t o n core (295 cm l o n g ) t h a t t h i s co re had n o t pene t ra ted t h e e n t i r e

f i n e sediment depos i t s t o t h e o r i g i n a l r i v e r bed (see F igu re 17) . No r a p i d

decrease i n r a d i o n u c l i d e concent ra t ions was observed i n t h e bottom sediment

sec t i ons as observed i n t he McNary Dam and P o r t Ke l l ey p i s t o n cores, which

migh t i n d i c a t e the presence o f t he o r i g i n a l r i v e r bed. However, f rom t h e depth

( l H 9 13M Atla) 6 l lu lp 'NO l l t l t l lN33N03

(lH3 13M A t r a 1 ~ I W P 'NO l l ~ t r l N 3 3 ~ 0 3

d i s t r i b u t i o n s o f t he rad ionuc l i des i n t he o t h e r p i s t o n cores i t appears c e r t a i n

t h a t t h e bottom sediments a t t h e Hat Rock l o c a t i o n would con ta in very low l e v e l s

o f r a d i o a c t i v i t y .

RADIONUCLIDE INVENTORY I N McNARY RESERVOIR

With t h e a c q u i s i t i o n o f the rad ionuc l i de concentrat ions i n t he p i s t o n cores - w - and from t h e c h a r a c t e r i z a t i o n o f sediment depos i ts f rom the sub-bottom seismic

4

survey, an es t imate o f t h e t o t a l q u a n t i t i e s o f gamma-emitting rad ionuc l i des i n

t h e sediment o f McNary Reservoir can now be made. I f we assume t h a t t h e deepest - -

s i 1 ty sediment depos i ts extend approx imate ly 500 meters f rom the Oregon shore - . ( t h i s es t imate i s based on seismic p r o f i l i n g of the r i v e r bottom) a t an average %

sediment depth o f 3 meters throughout t he 40 km s t r e t c h o f r i v e r between Wal lu la

Gap and McNary Dam, and assuming a sediment dens i t y o f 2.4 g/cm3, then approx i -

mate ly 1 . 4 ~ 1 0 ~ ~ g of sediment are present i n t h i s s t r e t c h o f t he r i v e r . The

average concent ra t ion o f the f o l l o w i n g rad ionuc l ides , i n D/M/g, was measured i n

t he p i s ton cores f rom top t o bottom t o be: 4 0 ~ - 30; 55Fe - 70 (est imated) ;

60Co - 9.6; 1 3 7 C ~ - 7.5; 1 5 2 - 1 5 4 ~ ~ - 8.2; 2 3 9 - 2 4 0 P ~ - 0.10, 2 3 8 P ~ - 0.0050;

54Mn - 0.15; 241Am - 0.023; 228Th - 1.0; 226Ra - 3.0; and 65Zn - <0.3. M u l t i -

p l y i n g these average concentrat ions by t h e t o t a l sediment deposi ts g i ves t h e

f o l l o w i n g rad ionuc l i de i n v e n t o r i e s i n t o t a l cu r i es (see F igure 20): ' 40K - 1900;

55Fe - 4000; 60Co - 600; 137Cs - 470; 1 5 2 - 1 5 4 ~ ~ - 520; 239-240Pu - 6.3; 54Mn- 9.4;

241Am - 1.5; 228Th - 63; 226Ra - 190; and 65Zn - 18. When d i s t r i b u t e d throughout

t h e vas t sediment deposi ts behind McNary Dam these i n v e n t o r i e s a r e present i n

very d i 1 u t e concent ra t ions i n t he sediments.

I f we assumed t h a t the remaining 1000 meters across t h e r i v e r was charac-

t e r i z e d by a s i l t y bottom one meter t h i c k (a very l i b e r a l es t imate based on

c u r r e n t knowledge), t h i s would increase the rad ionuc l i d e i n v e n t o r i e s by o n l y

25%.

SUB-BOTTOM SEISMIC SURVEY OF McNARY RESERVOIR BOTTOM

Previous s tud ies have shown t h a t the sediment deposi ts behind McNary Dam

represent a s i g n i f i c a n t r e p o s i t o r y o f Hanford o r i g i n rad ionuc l i des (1,3,8)

I nven to r i es o f 4 6 S ~ , 5 1 C r , 54Mn, 60Co and 65Zn conta ined i n t h e sediment

depos i ts between Pasco and McNary Dam and between Pasco and Vancouver were

est imated i n 1966 y3). However, these i nventory est imates were concerned

NOTE: PERCENTAGES I N PARENTHESES REPRESENT THE FRACTION OF THE TOTAL RADIOACTIVITY CONTRI BUTED BY EACH RADIONUCLI DE.

FIGURE 20. Est imated I n v e n t o r i e s o f Radionucl ides ( i n Cur ies) Associated w i t h Sediment Deposits Behind McNary Dam September 1976

w i t h on ly the upper few tens o f cent imeters o f sediments, s ince the concen-

t r a t i o n s o f the s h o r t - l i v e d rad ionuc l ides decreased f a i r l y r a p i d l y w i t h sediment

depth and the deep sediments were ignored. I n order t o est imate the i n v e n t o r i e s

o f the l o n g - l i v e d rad ionuc l ides now contained i n McNary Reservoi r sediments

i t i s necessary t o know the ex ten t o f t h e area l and v e r t i c a l d i s t r i b u t i o n s of

sediments and t h e i r rad ionuc l i de concentrat ions from top t o bottom. From our

previous sediment sampling experience and from est imates o f sedimentat ion r a t e s

ca l cu la ted from the change i n rad ionuc l i de concent ra t ion r a t i o s as a f u n c t i o n

o f sediment depth, we knew t h a t as much as 3 t o 7 meters o f sediment had accu-

.mulated i n r a p i d l y sedimenting areas o f the McNary Reservoir . We a l so knew

t h a t these h i g h l y sedimenting areas were loca ted along the Oregon s ide o f t he

Columbia R iver between Por t Ke l l ey and McNary Dam. However, we d i d n o t know

any o f t he d e t a i l s concerning the ex ten t of the area l and v e r t i c a l d i s t r i b u t i o n s

o f sediments throughout the e n t i r e McNary Reservoir . This i n fo rma t ion i s

essen t i a l f o r es t imat ing rad ionuc l i de i nven to r i es i n the sediment deposi ts .

Therefore, Hol osoni cs , Inc. o f R i ch l and, Washington was empl oyed t o conduct

a sub-bottom seismic survey of the McNary Reservoir bottom t o charac ter ize the

sediment deposi ts . A d e t a i l e d r e p o r t prepared by Hol osonics, Inc . i s inc luded

i n the Appendix, which describes the techniques employed and the r e s u l t s t h a t

were obtained.

I n general, the Holosonics survey v e r i f i e s what we had conceived the sedi -

ment d i s t r i b u t i o n would resemble (see Figure 21 ). The seismic survey d i d reveal

the presence o f deep pockets o f sediments i n roughly contoured areas near the

Oregon s ide o f t he r i v e r . A major d iscovery was the presence o f f i n e sediment

deposi ts along a sec t i on o f the Washington s ide o f t h e r i v e r several k i lometers

above McNary Dam.

The average th ickness o f t he f i n e sediment deposi ts a long the Oregon s ide

o f the r i v e r i s approximately 3 meters. This value was used i n computing the

mass o f t h e major f ine-gra ined sediment deposi ts i n the r e s e r v o i r . - .

a '

CONCLUSIONS

The Columbia R iver has shown the a b i l i t y t o s a f e l y and e f f i c i e n t l y

a s s i m i l a t e the res idua l r a d i o a c t i v i t y remaining the the r i v e r sediments f rom c

-a

past Hanford operat ions.

I n f a s t - f l o w i n g s t re tches o f the r i v e r between Hanford and Wal lu la Gap (and

o the r l o c a t i o n s downstream from McNary Dam) the rad ionuc l ides associated w i t h

bottom depos i t s a r e scoured f rom t h e r i v e r d u r i n g t h e s p r i n g f r e s h e t s and

depos i ted i n r e l a t i v e l y s l a c k water reg ions o f t he r i v e r , p r i m a r i l y behind

McNary Dam. Fo l l ow ing the shut-down o f t h e Hanford r e a c t o r s no ma jo r r e l eases

o f r ad ionuc l i d e s t o t h e r i v e r has occur red (N-Reactor o c c a s i o n a l l y re leases

very smal l amounts o f s p e c i f i c r ad ionuc l i d e s ) , and the areas o f h i g h sed i -

menta t ion a r e now be ing b lanke ted w i t h r e l a t i v e l y uncontaminated sediment

depos i ts . The f o l l o w i n g conc lus ions can be drawn rega rd ing t h e f a t e o f t h e

remain ing i n v e n t o r y of r a d i onucl i d e s con ta ined i n t h e sediments:

1 ) Sur face sediments behind McNary Dam now c o n t a i n ext remely low

concen t ra t i ons o f Hanford o r i g i n r ad ionuc l i des due t o d i l u t i o n

wi t h uncontaminated sediments and t o r a d i o a c t i v e decay. The

ma jo r gamma-emitters a r e now 60Co, 1 3 7 C ~ and 1 5 2 - 1 5 4 E ~ . Trans-

uranium rad ionuc l i des (Pu and Am) a r e p resen t i n t h e sediments

a t n e a r - f a l l o u t l e v e l s .

2 ) S ince t h e shut-down o f t h e l a s t r e a c t o r w i t h s i n g l e pass c o o l i n g

i n 1971 approx imate ly 40 t o 80 cm o f new, r e l a t i v e l y uncontaminated

sediments have now covered t h e most r a d i o a c t i v e sediments.

3 ) Sub-bottom se ismic surveys revea l t h a t approx imate ly 3-meter t h i c k

s i l t y sediment depos i t s have accumulated i n t h e McNary Reservo i r

between Wal lu la Gap and McNary Dam on t he Oregon s i d e o f t h e r i v e r

s i nce t h e c r e a t i o n o f t he McNary Reservo i r i n 1953. Occas iona l l y

deeper sediment depos i t s appear t o occur i n pockets. The average

sed imenta t ion r a t e between 1953 and 1976 f o r these l o c a t i o n s v a r i e d

from about 5 t o 18 cm/yr. The mid-channel and Washington s i d e sed i -

ments appear t o be composed ma in l y of coarser sands, p o s s i b l y o l d

sand bars f rom the o r i g i n a l r i v e r bed.

4 ) Radi onucl i d e concent ra t ions i n deep p i s ton core sediments i n d i c a t e

t h a t no unusua l l y h i gh r a d i o a c t i v i t y re leases t o t h e r i v e r occur red

d u r i n g t he e a r l y peak years (1953-1963) o f ope ra t i ons a t Hanford.

5) T o t a l i n v e n t o r i e s o f gamma-emi t t i n g r a d i onucl i d e s i n t he major

sediment depos i t s behind McNary Dam have been es t imated t o range

from approx imate ly 600 c u r i e s f o r 60Co t o 9.4 c u r i e s f o r 54Mn.

The 2 3 9 - 2 4 0 P ~ i nven to ry i s es t imated t o be about 6.3 c u r i e s . The

X-ray e m i t t e r 55Fe i n v e n t o r y i s es t imated a t 4000 c u r i e s .

6 ) The buried inventory of sediment associated residual radio- nucl i des i n McNary Reservoi r poses no radi 01 ogi cal hazard t o human or animal populations.

REFERENCES

R. W. Perkins, J. L. Nelson and W. L. Haushild, "Behavior and Transpor t o f Radionucl ides i n the Columbia R iver Between Hanford and Vancouver, Wash- i ngton," Limn01 ogy and Oceanography 11 , 235-248 (1 966).

C. D. Becker, "Aquat ic Bioenvironmental Studies i n the Columbia R iver a t Hanford, 1945-1971. A B ib l iography w i t h Abstracts . " BNWL-1738, UC-48, B a t t e l l e y Paci f i c Northwest Laborator ies, Rich1 and, WA, Rebruary , 1973.

J. L. Nelson and W . L. Haushild, "Accumulation o f Radionucl ides i n Bed Sediments o f the Columbia R ive r Between the Hanford Reactors and McNary Dam, " Water Resources Research 6, 130-1 37 (1 970).

W. L. Haushild, H. H. Stevens, J r . , J. L. Nelson, and G. R. Dempster, J r . , "Radionucl ides i n Transpor t i n the Columbia R iver f rom Pasco t o Vancouver, Washington," Open F i l e Report (TID-25894), U. S. Dept. o f I n t e r i o r , Geo- l o g i c a l Survey, Water Resources D iv i s i on , Por t land, Oregon, 1971.

J. L. Glenn and R. 0. Van At ta , "Relat ions Among Radionucl i d e Content and Physica l , Chemical and Minera l Character i s t i c s o f Columbia R iver Sediments, " Geological Survey Pro fess iona l Paper 433-M, U. S. Dept. o f I n t e r i o r , Geological Survey, 1973, ava i lab1 e from: Superintendent of Documents, U. S. Government P r i n t i n g O f f i c e , Washington, D. C. 20402.

D. W. Habbell and J. L. Glenn, " D i s t r i b u t i o n o f Radionucl ides i n Bottom Sediments o f t he Columbia R iver Estuary," Open F i l e Report (TID-25724), U. S. Dept. of I n t e r i o r , Geologica l Survey, Water Resources D iv i s i on , Por t1 and, Oregon, 1971.

G. L. Toombs, "Lower Columbia R iver Environmental Survey i n Oregon," D i v i - s i on o f S a n i t a t i o n and Engineering, Oregon Sta te Board o f hea l th , Por t land, Oregon, 1966.

D. E. Robertson, W. B. S i l k e r , J. C. Langford, M. R. Petersen and R. W. Perkins, "Transpor t and Dep le t ion o f Radionucl ides i n the Columbia River," I n : Radioact ive Contamination o f t he Marine Environment -- Proceedings o f a Symposium, Seat t le , J u l y 10-14, 1972, IAEAy Vienna, 1973.

C. E. Cushing, D. G. Watson, D. E. Robertson and W. B. S i l k e r , "Decl ine of R a d i o a c t i v i t y i n the Columbia R iver - McNary Reservoi r Ecosystem Fol lowing Shutdown o f Hanford Reactors", BNWL-1850, Pt . 2, UC-48, pp. 84-88, January, 1974.

APPENDIX A

HOLOSONICS, INC. REPORT ON:

Sub-bottom Seismic Survey P o r t o f Walla Walla t o McNary Dam, Columbia R i v e r

SUBBOTTOM SEISMIC SURVEY

PORT OF WALLA WALLA TO

McNARY DAM, COLUhlBIA RIVER

S u b m i t t e d T o :

BATTELLE NORTHWEST LABORATORIES B a t t e l l e B o u l e v a r d

R i c h l a n d , W a s h i n g t o n 99352

S u b m i t t e d By:

HOLOSONICS, INC. 2400 S t e v e n s D r i v e

R i c h l a n d , W a s h i n g t o n 99352

June 8, 1977

SUMMARY O F

CONCLUSIONS AND RECOMMENDATIONS

A . Fine g ra ined sediments ( s i l t ) w e r e l o c a t e d a d j a c e n t t o

t h e Oregon shore l i n e between Twin S i s t e r s and McNary

Dam a s shown i n Appendix A .

B. Coarser g ra ined sediments (Sand) w e r e l o c a t e d above

Twin sisters and a r e p r e s e n t a c r o s s t h e e n t i r e a r e a

surveyed.

C . Surveys run p a r a l l e l t o t h e r i v e r channe l (Numbers 1,

2 , 3 , 4 , l A , 2A, 3A and 4A) were c h i e f l y used i n d a t a

r educ t ion . Cross surveys t r a n s e c t s A through G and A ' ,

AA, AA') were of l e s s e r va lue i n sediment l o c a t i o n s .

D. B y p rov id ing minor mod i f i ca t ions t o t h e survey system

a s p re sen ted , a more e f f e c t i v e system can be provided.

INTRODUCTION

The e a r t h and p l a n e t a r y chemis t ry s e c t i o n of B a t t e l l e Pac i -

f i c Northwest L a b o r a t o r i e s i s conduct ing a program t o s t u d y

t h e t r a n s p o r t and d e p l e t i o n of r a d i o n u c l i d e s i n t h e Columbia T

River . I n t h e conduct of t h i s s t u d y , it i s neces sa ry t o

s e c u r e sediment samples from t h e r i v e r bottom which i n t u r n

w i l l be s u b j e c t e d t o l a b o r a t o r y a n a l y s e s . To more e f f i - . i

c i e n t l y d e f i n e l o c a t i o n s where such samples should be ob-

t a i n e d , a thorough knowledge of sediment d e p o s i t s should be r e

known. Because of t h e l a c k of d e t a i l e d d a t a on t h e l oca - s t -

t i o n s and t h i c k n e s s of t h o s e d e p o s i t s , Holosonics t F i e l d

S e r v i c e s Department i n con junc t ion w i t h B a t t e l l e P a c i f i c

Northwest L a b o r a t o r i e s , has conducted a s e r i e s of sub-bottom

se i smic su rveys on t h e Columbia River . The su rveys w e r e

des igned t o determine a r e a s of maximum sediment bu i ld -up t o

assist i n t h e l o c a t i o n of f u t u r e sampling p o i n t s .

A t o t a l of f o u r , 26-mile t r a v e r s e s were performed p a r a l l e l

t o t h e r i v e r channel . A t o t a l of n i n e t r a n s e c t s w e r e p e r -

formed a t r i g h t a n g l e s t o t h e r i v e r a x i s a t l o c a t i o n s 'de-

termined by B a t t e l l e P a c i f i c Northwest L a b o r a t o r i e s . From

t h e s e surveys , a u sab le sediment i n v e n t o r y has been ob ta ined .

P r o j e c t Methodology

To accomplish t h e d e l i n e a t i o n of t h e d e p o s i t s , Ho loson ic s t

F i e l d S e r v i c e s Department provided a water-borne a c o u s t i c a l

surveying technique . This t echn ique , e f f e c t i v e l y r e f l e c t i o n

seismology, i n v o l v e s t h e u se of a s p e c i a l l y des igned acous- - .

t i c t r a n s c e i v e r system. . . rl

The technique employs t h e u se of an a c o u s t i c a l e lement C .

( t r a n s m i t t e r ) p u l l e d by a boa t . The t r a n s m i t t e r i s a c t i -

v a t e d , g e n e r a t i n g an a c o u s t i c p u l s e which i n t u r n p e n e t r a t e s .

t h e s u b s u r f a c e b e n e a t h t h e r i v e r . When t h e p u l s e s t r i k e s an

a c o u s t i c impedance mismatch, a s i g n a l i s r e f l e c t e d back t o

t h e r e c e i v e r . These s i g n a l s are t h e n p r o c e s s e d and d i s -

p l a y e d on a permanent t i m e h i s t o r y r e c o r d . Knowledge of t h e

approximate a c o u s t i c wave v e l o c i t y ( c o m p r e s s i o n a l wave)

a l l o w s f o r t h e c o n v e r s i o n of t h e t i m e - h i s t o r y d a t a i n t o

d e p t h s ' o f t h e r e f l e c t i n g h o r i z o n s . By o b t a i n i n g numerous

d e p t h sound ings on a t r a v e r s e i n t h e r i v e r a p r o f i l e o f t h e * s u b s u r f a c e c o n d i t i o n s can be o b t a i n e d .

The p e n e t r a t i o n of t h e a c o u s t i c waves i n t o t h e s e d i m e n t s i s

c o n t r o l l e d by t h e a c o u s t i c f r e q u e n c y and a t t e n u a t i o n c h a r -

a c t e r i s t i c s of t h e sed iment . F u r t h e r , t h e r e s o l u t i o n o f

s p e c i f i c boundary c o n d i t i o n s i s c o n t r o l l e d by t h e a c o u s t i c

f r equency . T h e r e f o r e , a s u r v e y f r e q u e n c y must be chosen

which e n a b l e s b e s t p e n e t r a t i o n w i t h maximum r e s o l u t i o n . For

t h e s e s u r v e y s a f r e q u e n c y of 7.5kHz was chosen a s optimum.

During a c t u a l s u r v e y s a c o n s t a n t b o a t speed i s o b t a i n e d and

i t s d i r e c t i o n of t r a v e r s e i s r e c o r d e d . The a c o u s t i c i n -

s t r u m e n t s a r e t h e n p u l s e d a t a c o n s t a n t r a t e and r e f l e c t e d

d a t a i s r e c o r d e d . The p u l s e rate and p u l s e package w i d t h i s

o p t i m i z e d based on w a t e r d e p t h and assumed sed iment t h i c k -

n e s s . I n t h e s e s u r v e y s a p u l s e rate o f 8 p u l s e s p e r second

w i t h a .2ms p u l s e w i d t h was d e t e r m i n e d t o b e optimum.

Once t h e s e optimum boundary c o n d i t i o n s a r e e s t a b l i s h e d ,

changes i n t h e q u a l i t y o f r e c o r d e d d a t a c a n be made by

r e c e i v e r g a i n and r e c o r d e r c o n t r a s t c o n t r o l s . During t h e

s u r v e y , t h e seismic o b s e r v e r m o n i t o r s t h e r e c o r d e d d a t a and

a d j u s t s t h e i n s t r u m e n t t o m a i n t a i n q u a l i t y d a t a r e c e p t i o n .

Survey Equipment

The su rvey equipment c o n s i s t s o f t h r e e major subsys tems . An

ED0 Western P r e c i s i o n Bathymetr ic /Seismic Recorder Plodel

550A, a n ED0 Western Model 6 2 6 9 Hul l Mount Cone Transducer t

and Holoson ics ' MAP sys tem (Minera l Acous t ic P r o s p e c t i n g )

Model 7 5 A High Energy Acous t ic T r a n s c e i v e r . F i g u r e 1 shows

a b lock diagram of t h e survey sys tem. 4

,

The MAP System Model 75A p r o v i d e s e l e c t r i c a l energy a t a

s p e c i f i c f requency , power l e v e l and p u l s e w id th t o t h e cone - . - t r a n s d u c e r . F u r t h e r , t h e system a l s o p r o v i d e s a series of

a m p l i f i e r s and f i l t e r s f o r c o n d i t i o n i n g t h e r e c e i v e d s i g n a l s

b e f o r e t h e y are d i s p l a y e d on t h e s e i s m i c r e c o r d e r .

The ba thyme t r i c / s e i smic r e c o r d e r r e c e i v e s t h e d a t a from t h e

MAP System and r e c o r d s t h e r e c e i v e d s i g n a l th rough amp l i t ude

d i s c r i m i n a t i o n on h e a t s e n s i t i v e paper . T h i s - s y s t e m a l s o

p r o v i d e s command s i g n a l s t o t h e t r a n s c e i v e r t o e n s u r e p r o p e r

f i r i n g sequence of t h e t r a n s d u c e r .

The h u l l mounted cone t r a n s d u c e r p r o v i d e s t h e a c o u s t i c wave

package and s e r v e s a s t h e r e c e i v e r f o r t h e r e f l e c t e d acous-

t i c s i g n a l s . The t r a n s d u c e r i s des igned t o have a s p e c i f i c

beam p a t t e r n t o ensu re p roper d a t a r e c e p t i o n . F i g u r e 2

shows t h e beam c a l i b r a t i o n f o r t h e p a r t i c u l a r t r a n s d u c e r

used f o r t h i s p r o j e c t .

The t r a n s d u c e r was mounted on a t u b u l a r frame and was l o -

c a t e d on t h e s i d e o f t h e su rvey b o a t by means o f c o n t r o l

r o p e s and an e x i s t i n g boom. The bottom o f t h e t r a n s d u c e r

w a s l o c a t e d approx imate ly t h r e e f e e t underwater and i n a

f i x e d p o s i t i o n t o ensu re no c a v i t a t i o n and e l i m i n a t e minor

e f f e c t s from t h e survey boa t .

TRANSMIT

HULL MOUNT TRANSDUCER t-7

BATHYMETRIC/ S E I S M I C RECORDER

TRANSCEIVER MAP 75-A r CATHODE RAY TUBE

SUB-BOTTOM PROFILING SYSTEM

FIGURE 1 - A- 7

ACO-USTIC CALIBRATION FACILITY E0.-

Remarks

FIGURE 2

A-8

F i e l d Program

The conduc t of t h e sub-bottom s u r v e y s consumed e i g h t d a y s

s t a r t i n g A p r i l 11, 1977 and c o n c l u d i n g on A p r i l 20, 1977.

The i n i t i a l t h r e e d a y s w e r e s p e n t i n c a l i b r a t i o n , sys tem

performance check , c o r r e c t i n g minor m a l f u n c t i o n s and w a i t i n g

f o r s u i t a b l e wea the r c o n d i t i o n s .

A t o t a l of 17 s u r v e y s were t h e n conducted from A p r i l 1 4 t o

A p r i l 20th . E i g h t of t h e s u r v e y s were performed p a r a l l e l t o

t h e r i v e r c h a n n e l a s f o l l o w s :

Twin sisters to M c N a r y Darn, 100 yards off the Oregon shore

line, 2 1 miles length

April 15 - S u w e y # 2

Twin Sis ters to !.lcNary Darn, 200 yards off the Oregon shore

l ine , 21 miles length

. April 18 - Survey #3

Twin Sis ters to McNary Dam, mid-channel, 21 miles length .

nYin Sis ters to M c N a r y Dam, 200 yards off Washington shore

line, 21 miles length

Cantinuation of Surveys #1 through #4 upstream fran Win

S i s e r s adjacent to the Port of Walla Walla, 20 miles total

A t o t a l o f n i n e surveys were performed a t r i g h t a n g l e s t o

t h e r i v e r a x i s from A p r i l 15 t o A p r i l 20th as fo l lows:

8 . April 15 - Transect A - M d d a r y Dam, 100 yards upstream f r m

bmy l ine

April 15 - Transect B - Center of M c N a r y Park, swhning lagoon

April 18 - Transect C - Hat Rock State Park, a t navigation

range marker

~i l i t . ~ ~ 1 i~ d L A . , 7 , L L - . ~ - ; ~ ~ L ~ ~ L ] - L ~ & - A , ~ ~ ~ ~ ~ ~ ~ ~ - l x ~ w ~ ~ ~ n ~ i ~ ~ LLAIS - -- -- . - - - .- - - --- Apqi;1, ,$8,T ,%ansect AA - & N a r y Dam, halfway between buoy l i ne

@ AI ,1 I I 1 a 1 L ~i iL,t>~ ' L --& . - - - - - - - --- :,1u';,r\+ ; h . ; i , lid1 hidl I X E V J e a ' k ~ d l ,L,.XIt

4~!r&,l8~ ,:, , R q g e c t AA ' - McNary Dam, halfway between Transec t

AA and p e r h o u s e

April 19 - Transect F - Port Kelley

m April 19 - Transect E - Juniper -. A ~ L L : - '*'icu,a,Lt J - u ~ L S * ~ - a n d i d tk tqc isldd ---

a April 19 - Transect D - Upstream end of Refuge Island

April 19 - Transect A l l - McNary Dam upseeam from buoy l ine

(sarrre a s Transect A)

April 20 - Transect G - Adjacent to Port of Walla Walla

1nc luded . i -n Appendix A , "River c h a r t s 1 ' a r e t h e l o c a t i o n s of

a l l surveys performed.

Survey Data

Appendix B c o n t a i n s p e r t i n e n t examples of o r i g i n a l f i e l d

d a t a ob ta ined du r ing t h e f i e l d surveys . Located a long the

t o p edge of t h e s e survey r e c o r d s a r e t i c marks and d a t a

concerning t h e l a t e r a l e x t e n t and sediment t h i c k n e s s as

ana lyzed by Holosonics ' F i e l d S e r v i c e s Department s t a f f .

Appendix A "River Cha r t s " a l s o c o n t a i n s p l o t t e d d a t a a s t o

sediment ( s i l t and sandy s i l t ) l o c a t i o n s based on ou r ana-

l y s e s of survey d a t a and geo log ic i n t e r p r e t a t i o n , and r e -

s u l t s of f i e l d sampling programs conducted by B a t t e l l e

P a c i f i c Northwest Labora to r i e s .

Contained i n Tables I through I V i s a sediment i n v e n t o r y

taken from t h e f i e l d d a t a . The l o c a t i o n (yardage from

survey c o n t r o l po in ' t s ) i s based on ou r c a l i b r a t i o n of b o a t

speed and l o c a t i o n , v e r s u s r eco rd l e n g t h . The a c t u a l l o -

c a t i o n s of t h e sediment d e p o s i t s w i l l v a ry from t a b u l a t e d

d a t a due t o i n a c c u r a c i e s of b o a t speed and a b s o l u t e l o c a t i o n

of boa t . However, by us ing f i e l d r e c o r d s , t h e l o c a t i o n of

d e p o s i t s can be d u p l i c a t e d t o approximately + 2 0 ya rds .

Also conta ined wi th t h e sediment i nven to ry i s ou r e s t i m a t e

of sediment t ype base of f i e l d d a t a and geo log ic i n t e r p r e -

t a t i o n .

During d a t a a n a l y s i s it became apparen t t o ou r s t a f f t h a t

t h e c r o s s surveys were of l e s s e r va lue than t h e down r i v e r

t r a v e r s e s . This i s due t o t h e spacing of t h e c r o s s t r a n s -

e c t s which does n o t a l l ow c o r r e l a t i o n between a d j a c e n t s e t s

of d a t a . These surveys con ta in v a l u a b l e d a t a and provide a

b a s i c unders tanding of t h e r i v e r system neces sa ry t o any

i n t e r p r e t a t i o n . However, t h e d a t a could n o t be used t o any

g r e a t e x t e n t f o r sediment d e p o s i t l o c a t i o n ( excep t a t McNary

Dam) and a l l r e s u l t s a r e based on down r i v e r t r a v e r s e s .

Survey R e s u l t s

A s can be seen i n Appendix A , our i n t e r p r e t a t i o n shows s i l t

and sandy s i l t type d e p o s i t s l oca t ed g e n e r a l l y a long t h e

Oregon sho re l i n e . These d e p o s i t s are f e l t t o be l o c a t e d on

t h e low a n g l e s l o p e s a d j a c e n t t o t h e s h o r e l i n e and g e n e r a l l y

d o n o t e x t e n d t o t h e c e n t e r l i n e of t h e r i v e r . The c e n t r a l

s e c t i o n and Washington s i d e o f t h e r i v e r e x c e p t a s p l o t t e d

i n Appendix A , i s composed o f s i l t y s a n d , sand and c o a r s e

a g g r e g a t e o r rocky bot tom d e p o s i t s .

G e n e r a l l y , t h e a r e a s u r v e y e d , l y i n g ups t ream from P o r t

K e l l e y , i s composed m o s t l y o f sand and c o n t a i n s l a r g e r i p p l e

marks a s shown i n Appendix A & B.

9

. A l l s ed iment t h i c k n e s s e s a r e based on t h e zssumed p r i m a r y

wave v e l o c i t y of 5 0 0 0 f e e t p e r second. . T h i s v e l o c i t y s h o u l d

be v e r i f i e d by l a b o r a t o r y t es t s on c o r e samples from a c t u a l

r i v e r d e p o s i t s .

SUHVEY #1

100 Yards Off Oregon Shore Line - ! l W h Sis te r s to Mary Dam *

PROBABLE SEDli'rn IDCATION* LENGTH 'MICKNESS** TYPE

1- 1 + 1,180 yds. 100 yds.

_I 1- 2 + 380 yds. 1,440 yds. d

1- 3 + 960 yds. t o - 1 - 4 + 4Oyds.

6 80yds. - 1 - 6 + 44Oyds. 600 yds.

1 - 7 + 960yds. 360 yds.

1- 8 + 100 yds. 200 yds.

1- 9 - 360 yds. 360 yds.

1-10 + 650 yds. 200 yds.

1-11 + 660 yds. t o 1-12 + 770 yds. - 1-14 + 280 yds. t o 1-15 + 190 yds. -

1-15 + 190 yds. t o 1-16+ 50yds.

1-16 + 960 yds. t o 1-17+ 50yds. -

1-19 + 660 yds. to . . 1-21 - - - 1-21 + 140 yds. 680 yds.

; '#

1-21 + 720 yds. 480 yds.

1-22+ 48Oyds. 480 yds. .d

1-2 3 800 yds.

Si l t y

2' up to 12' pock. S i l t y

9 ' s i l t y (

S i l t y

s i l t y (~~~~ -

5-7 ' Si l t y I Star t 3-4', Center 15-18', Ehd 4-6' Si l t y

1-3 ' S i l t t o Sandy S i l t I S i l t t o Sandy S i l t

A I S i l t to Sandy S i l t

8-14 ' Si l t y to Sand S i l t J *Based on our calibration of f i e ld data

*XVp asfllmed at 5000 ft/sec.

SURVEY #1

100 Yards Off Oregon Shore Line - Twin S i s t e r s to M c N a r y Dam

1 - 2 5 + 42Oyds. 500 yds.

800 yds.

1-27 + 800 yds. to 1-28 - 350 MS. -

1-28+ 72Oyds. 400 yds.

1-28 + 1,120 yds. t o E d o f Survey

PROBABLE SEDIMENT THICKNESS** TYPE

L

1-3 '

Var . t o 15 '

Var. to 20' '

10-12'

S i l t y

S i l t y

10-15' w i t h thin pockets a t i r r e g u l a r intervals

*Based on our c a l i b r a t i o n of f i e l d d a t a **Vp assumed a t 5000 ft/sec

TABLE I1

200 Yards O f f Oregon Shore Line - Twin Sistersto M c N a r y Dam

PROBABLE s m m LENGTH THICKNESSk* TYPE

800 yds. 8-12 ' s a r d y S i l t to S i l q d 2- 3 + 100 yds. t o e

i 2- 4 + 60 yds. - . + Var. 4-10' .

2- 7 1,000 yds. 6-12 ' S i l t y

2- 8 to 2-9 - 2-4 '

2- 9 + 850 yds. t o 2-10 + 1,100 yds. 4-8 ' f.ilty

2-10 + 1,100 yds. t o 2-14 + 400 yds. 1-3 ' S i l t to S i l t y Sand

2-14 + 400 yds. to 2-14 + 2,700 yds. 2-5 ' w/ Sandy S i l t to Sand

10-15' Pockets

2-14 + 2,700.yds. t o J 2-16 + 1,500 yds. - S& S i l t to Sand

2-16 + 1,500 yds. 500 yds . 5-7 ' S i l t y Sand to S i l t

2-16 + 2,000 yds. t o 2-21 - 2-3 '

2-22 to 2-23 200 yds. 2-3 ' S i l t y

2-23 - 200 yds. to 2-23 + 200 yds. 4-5' Local Pockets

. - 2-24 to Erad 5-12' Thick pocket - in 1-3 ' -era1 Thickness

-. ; b

*Based o n our c a l i b r a t i o n of field data + *Vp assurred a t 5 ~ 0 0 f t / s e c .

TABLE I11

SURVEY #3

Mid-Channel - M n Sis te r s to Mary Dam

. PROBABLE SEDIMENT

TYPE

L

Sand 3- 1 + 1,300 yds. t o 3- 6 - Var. up to 8'.

' Sand - Sand Maybe Sane S i l t 5-12' Pockets

Sand Maybe Sane S i l - @ 4-5' Occasional 12 ' , Pockets

3-14 + 400 yds a t Hat Rock Sta te Park Transect C - Weak Indication

of 12' Pockets Sand Maybe sane

Sand 3-14 + 1,100 yds. - 4-5' Pockets

3-14 + 1,400 yds. 200 yds. 3-4 ' Sand Pockets Gradin To S i l t t

Sand & S i l t

Sandy S i l t to S i l t

3-1 0 ' Variable

3-15 + 1,150 yds. 500 yds. 10 '

Sandy KT 5-8 ' Sandy S i l t To S i l t I

I - .

10-12 ' Sand - 3-17 + 600 yds. 400 yds.

Faugh Bottan with Pock & Sand Uxal Pockets

of Sand

*Based on our calibration of f i e l d data **Vp assurred a t 5000 ft/sec.

TABLE I V

200 Yards Off Washington Shore - Twin Sis ters to M c N a r y Dam w

PIiOBABLE SEDIMENT

ttf . LQCATION* LJmZTH THICKNESSk* TYPE

-. - 4- 1 to 4-2 - 200 yds.

-$

4- 4 + 900 yds. t o ' r - 4- 5 + . 300 yds. - -

4- 5 + 300 yds. 200 yds.

-1 Sand

4- 5 + 500 yds. 900 yds. 6-10' Grading to 3-6' s m n

4- 6 + 900 yds. 700 yds. - Rock Bottom and Gravel

4-10 + 1,400 yds. 75 yds. 3-5 ' Pockets t o 1 2 '

4-12 + 750 yds. t o 4-13 + 300 yds. 5-10 ' Variable Sand & S i l t

4-13 + 300 yds. t o 4-15 - 2-5' Variable Sandy S i l r' '\

I i

4-17 - 1,100 yds. t o 4-18 + 800 yds. -

4-18 to Finish - Variable to None

*Based on our calibration of f i e ld data *Wp assumed a t 5000 ft/sec.

. - -

TABLE V

All hca t ions are Referenced F'ran Oregon Shore Line

0 yds. t o 500 yds. 10-12 '

. 600 yds. to130U yds. 2-6 '

1400 yds. t o 1550 yds. 3-9 '

1600 yds. t o 1800 yds. 3-4'

0 yds. t o 550 yds. 6-12 '

630 yds. t o 680 yds. 2-4 '

770 yds. t o 1020 yds. 6-7 '

1020 yds. t o 1530 yds. 10-12 '

0 yds. t o 730 yds.

700 yds. t o 1225 yds.

SURVEY AA'

P m m s m m t

TYPE

Si l t y

S i l ty

S i l t y

S i l t y

S i l t y

S i l t y

S i l ty

S i l t y

S i l t y

CONCLUSIONS

Based on sub-bottom surveys and geo log ic i n t e r p r e t a t i o n it

i s ou r op in ion t h a t t h e m a j o r i t y of f i n e g r a i n e d sediments

a r e l o c a t e d a d j a c e n t t o t h e Oregon sho re l i n e and are l o -

c a t e d on t h e bench (low ang le ) s t r u c t u r e s .

During t h e conduct and a n a l y s e s of surveys it became ap-

p a r e n t t h a t t h e a c o u s t i c n a t u r e of t h e sediment d e p o s i t s

were complex. That i s , t h e impedance mismatch ( u l t i m a t e l y

t h e r e f l e c t i o n c o - e f f i c i e n t ) of t h e r i v e r d e p o s i t e d s i l t s

ove r ly ing t h e t e r r e s t r i a l s i l t s i n t h o s e a r e a s where t h e

pool inunda ted t h e sur rounding land i s v e r y low. Th i s low

mis-match c r e a t e s a low ampli tude ( r e l a t i v e ) r e t u r n s i g n a l

which i s d i f f i c u l t t o r eco rd . F u r t h e r , t h e a t t e n u a t i o n of

some of t h e s i l t d e p o s i t s appears t o be h igh a t t h e £re -

quency used (7 .5 kHz) .

These two a c o u s t i c c h a r a c t e r i s t i c s coupled w i t h t h e l a r g e

v a r i a t i o n i n wate r dep th , compound t h e d a t a complex i ty .and

make i n t e r p r e t a t i o n d i f f i c u l t . F u r t h e r , p r o f i n g i n shal low

water approximately f i f t e e n f e e t o r l e s s adds f u r t h e r com-

p l e x i t y t o d a t a r e d u c t i o n because t h e r e t u r n s i g n a l s a r e

l o c a t e d w i t h i n t h e i n s t rumen t ringdown and m u l t i p l e r e f l e c -

t i o n s of t h e f i r s t bottom. Although t h e s e c o n d i t i o n s e s -

s e n t i a l l y degrade t h e sub-bottom d a t a , t h e i r e f f e c t can be

reduced o r e l imina t ed by provid ing m o d i f i c a t i o n t o t h e

survey techniques and systems a s o u t l i n e d under recommendations.

The sub-bottom p r o f i l i n g technique has t h e a b i l i t y t o de-

l i n e a t e t h e s e and o t h e r sediment d e p o s i t s w i t h t h e h e l p of

geo log ic a n a l y s e s and d a t a from a c t u a l sampling programs.

I t i s f e l t t h a t t h i s survey technique and systems w i t h minor

mod i f i ca t ion can provide enhanced d a t a on sediment l o c a t i o n

which would not require extensive geologic analyses or pre-

. survey sampling if the recommendations contained below are

followed.

Recommendations

To provide complete sub-bottom profiling capabilities for

the Columbia River sediment deposits, the f,-illowing recom- t.

mendations and modifications are suggested:

a Provide greater control on position of survey

vehicle. This will allow for more accurate re-

construction of data points for sampling programs.

a Provide a dual frequency (3.5 and 7.5 kHz) pro-

filing system. This will effectively eliminate

attenuation problems and reduce the effect. of low

impedance mismatch at boundaries.

a. Obtain occasional core samples for acoustic yelo-

city control.

Conduct additional cross river surveys to enable

better correlation of data.

Provide a calibration site near McNary Dam for

periodic system check.

a In shallow water areas, readjust the instrumen-

tation from normal settings to enhance the signals

contained in the ringdown and first bottom multiple.

APPENDIX A

Shown i n F i g u r e s 1, 2 and 3 are t h e l o c a t i o n s of a l l su rveys

conducted f o r t h i s p r o j e c t and approximate bounda r i e s o f

major sediment bui ld-up ( s i l t and sandy s i l t ) .

Traverses Run Parallel t o River Channel

=---IP - Transects R.m Perpendicular to River Channel

I%i jor Sedimnt Areas

APPENDIX B

The f o l l o w i n g c o n t a i n s a b r i e f d e s c r i p t i o n o'f d a t a r e d u c t i o n

methods and examples o f d a t a o b t a i n e d d u r i n g t h e s u r v e y s .

Data Reduct ion

Subbottom p r o f i l i n g d a t a i s reduced i n t h e same f a s h i o n a s

s t a n d a r d l a n d born seismic r e f l e c t i o n surT-;ing. Tha t i s , a

series o f t i m e - h i s t o r y r e c o r d s a r e o b t a i n e ? a t d i s c r e t e

p o i n t s a l o n g a su rvey l i n e and c o r r e l a t i o n i s made between

r e c o r d s based on a r r i v a l t i m e s of s i g n i f i c a n t s i g n a l sets.

F i g u r e B-IA shows a h y p o t h e t i c a l c r o s s - s e c t i o n o f a s u r v e y

a r e a . I n t h i s example, t h e t r a n s m i t t e r - r e c e i v e r e l ement i s

l o c a t e d a t t h e w a t e r s u r f a c e and i s towed from l e f t t o

r i g h t . Ray p a t h s a r e p rov ided t o show a c o u s t i c wave p r o -

p a g a t i o n . Ray p a t h Number 2 i s a c o n t i n u a t i o n o f P a t h 1

showing r i n g i n g i n t h e s u r f a c e l a y e r ( w a t e r l a y e r ) . Addi-

t i o n a l r i n g i n g o f t h i s t y p e w i l l o c c u r between Boundary A &

B i n t h e sed iment l a y e r b u t i s n o t shown t o a v o i d c o n f u s i o n .

F i g u r e B- IB shows t h e t i m e - h i s t o r y r e c o r d r e c e i v e d by t h e

i n s t r u m e n t b e f o r e s i g n a l p r o c e s s i n g ( t h i s s i g n a l would b e

symmet r i ca l a b o u t t h e Y-axis i n r e a l f i e l d d a t a ) . The

l o c a t i o n ( t i m e ) of e a c h r e c e i v e d s i g n a l i s a f u n c t i o n o f

wave p r o p a g a t i o n v e l o c i t y and p a t h l e n g t h . ~ a c h s i g n i f i c a n t

set o f s i g n a l s i s i d e n t i f i e d by t h e r a y p a t h t r a v e r s e d and

t h e boundary a t which it r e f l e c t s . S i g n a l A-2 i n d i c a t e s a

m u l t i p l e r e f l e c t i o n ( g h o s t ) from Boundary A caused by t h e

r i n g i n g o f t h e waves i n t h e s u r f a c e l a y e r .

The r e c e i v e d waves a r e t h e n p r o c e s s e d by a m p l i t u d e d i s -

c r i m i n a t i o n and d i s p l a y e d by t h e b a t h y m e t r i c / s e i s m i c re-

c o r d e r i n t h i r t e e n s h a d e s o f g r a y . T h e r e f o r e , e a c h t i c k

FIGURE Ei-IA

POSITION I POSITION I1 POSITION I11

23- !a- WATER SURFACE

FIGURE B-IB

POSITION I POSITION I1 POSITION I11

mark shown on t h e r e c o r d s r e p r e s e n t s t h e a m p l i t u d e of i n -

d i v i d u a l waves r e c e i v e d by t h e sys tem. I f t h e a r r i v a l t i m e s

of t h e , i n d i v i d u a l waves i s c o n s i s t e n t a l o n g t h e t r a v e r s e ,

t h e n t h e y a p p e a r a s l i n e a r f e a t u r e s . The l i n e a r f e a t u r e s

c a n be i n t e r p r e t e d a s e i t h e r t h e r i v e r bot tom o r boundary

c o n d i t i o n s p r e s e n t i n t h e s e d i m e n t s a s shown i n F i g u r e s B - I

A & B.

F i g u r e B - I 1 shows f i e l d d a t a w i t h t h e r e f l e c t i n g b o u n d a r i e s

h i g h l i g h t e d . The p a r a l l e l l i n e a t t h e b o u n d a r i e s a r e c r e a t e d

b e c a u s e t h e a c t u a l t r a n s m i t t e d energy i s a wave p a c k e t and

t h e r e c o r d e r a m p l i t u d e d i s c r i m i n a t e s e a c h i n d i v i d u a l wave i n

t h e p a c k e t .

WATER SURFACE (BOTTOM OF TRANSDUCER)

FIGURE B-I1 FIELD RECORD SHOWING FIRST ARRIVAL AND MULTIPLE REFLECTIONS

SEDIMENT REFLECTION (SEDIMENT-- BOTTOM BOUNDARY)

7 IU SEDIMENT MULTIPLE QI (SEDIMENT GHOST )

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BOTTOM REFLECTION (WATER-SEDIMENT BOUND?

BOTTOM MULTIPLE (BOTTOM GHOST)

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. . . . . . . . . - ,' . ,. .; ::.. I ' . . . . j . . . . j . . < ! . . ,

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. . . . . . I i SURVEY #2 I i

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. , i !! . . . . . . AT SAIvPLF: POINT, BUOY D: THIS RECORD WAS TAKEN I

. . . . -- 1 . . . - . .. . . . .*. . . . . - ..:;$; \ W I L E C I R C L I N G A M ) D R I l " r I N G ~ U N D T H E S ~ U N D P L E 1 .

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NESS OF 5 TO 12 FEET. THIS AREA KXJLD ALSO BE .... . .

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:: .... +, 4: ::;-:*. + :;z- . .. .Gy, FL+ *:-:+;. G: .. * .

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AVERAGE WATER DEP2II I S 38 FEET. + : ' - :: . : . - 1: 5 . .- . . . . ; : - " f :'.': * : '. ,- --, : 7 .: .; $:: > [. . . . . . :. ;. b; , . . .. . ............ .... ..... . . . .

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A P P E N D I X B

TABULATED RADIOtdUCLIDE CONCENTRATIONS

R A D I O N U C L I D E C O N C E N T K A T I O N S I N C O L U M B l A K I V E K S E D I M E N T

SAMPLE DATE: AUGUST 3, 1976 SAMPLE LOCATION: Pk IEST K A P I DS ( P k - A ) SAMPLING METHOD: GKAVITY COk lNG

dlm lg m

CORE DEPTH (cm)

R A D I O N U C L I D E C O N C E N T R A T I O N S I N C O L U M B l A R I V E R S E D I M E N T

SAMPLE DATE: AUGUST 4, 1976 SAMPLE LOCATION: HANFOKD FERRY, FAR SHORE (H-4) SAMPLING METHOD: GRAVITY COR ING

dlmlgm

CORE DEPTH (cm) - - --- 4 0 ~ 5 4 ~ n 6 0 ~ o 6 5 ~ n 1 3 7 ~ s 152-154E 22gTh 226ka 2 3 8 ~ u 239-240pu 2 4 1 ~ m - [XI

-- w 0-5.1 46.6 0.196 1.93 (0.5 2.06 1.34 1.43 7.54 Q00067 * 27 0.0104 * 6 0.0016 + 35

GRAB SAMPLE 35.9 0.087 0.944 <0.5 1.75 0. 666 0.628 3.98 HANFORD SLOUGH

L n N O - W S rn a r n O 3 0 N d r - i d d 0 d d ~ d O d t - 7 A N - A d d d d d d d d d d d

v v v v v v v v v v

"p e z z s > j8 0."~ Z

E E E rnzc 5 % I- .. a W i ' D mag - izLi 282 a-Jz w w - JJJ aaa S E E a a a

v v v v v v v v v v v

W 0 Z? Z

lx 0 O m 0 dz W 5 %

emo -. s z 0 > = - ? a Z I - w c r 0 - n . .

IS=' a " 0 2 r3c

i=t k i Z E < o m n J Z W W - JJ.J C L a C L E E S 6 6 6

m I + a u \ m ~ u \ ~ c u o 0 r - r n ~ % B g ~ a m r n h ~ - a o o 4 c u e b a d 0 1 S 2 2 3 E E k b 2 f 2 b O b b b b b b b b b

CV CV dddddddddddidddddddddd

a - - C T d \ O M \ O b W L n 0 - 0 Z - - a S m L n - O o a - o 1 8 - - - $ ;

m - b I c . ~ \ O \ O \ O \ O \ O \ O - \ O \ O \ O L n

E n cv d d d d d d d d d d d d d d d 3 1

5 0 0

3 W b C V O C ) C V e ~ ~ ~ \ O O ~ ~ d O ~ ~ L n C V ~ ~

Z I- - rn CL E 3 e

v,

d c 6 c 6 $ $ p $ ~ $ ~ & d d A

Z -

W E

Q* CTCTO -9 - y \ - a u

0 - n drid-*o:ddod&Sd<d,dd C r \ y r ' , U 0 0 h L n C V y r ' , Q * W M m C V b - - rn d d I- d d

a z cf I- C3 Z Z - W 0 I Z v, a 0 S a 0 -z W s z n - Z E Z Z d w N d d d d A - d d d N ca rn do . 1 E e z ddt-ldddddddddddd s w - Ln v v v v v v v v v v v v 3 ,a > Z Ln3a 0 I - b X

m m - C T ~ u ~ u - Q * o ~ . q q ~ - mwC3 ~ " g ~ g ~ ~ ~ ~ ~ ? ~ ~ ~ ~ ~ n 3 . . 4 s f a " a o g n - E

&?gLl s I-0s ZS,o g W W - W -A J a a a a w E E S E a a a o m v , v , 0

L?Y\qdCV q'%Ln C V L n b d d

I I I I q ~ $ & L n ~ \ O C V ~ C V o O r r \ Q * ~ C T L n c r \ U

ddd~~~~~~$~$d~

C T C O d C V 9 d-01 00- b m d d ~ N C V L n h C V d d m L n d m ~ ~ d 9 9 L n 8 d u L n h N N d C V d d d d d d u N C V C V m N m C V N m N m 4 d d d d d d d d d d d d d d d d d d d d d d d d

I v v v v v v v v v

&.gtz + U S aoC3 a d z W W - J d d C l C L a s z s a a a tntntn

R A D I O N U C L I D E C O N C E N T R A T I O N S I N C O L U M B I A K l V E K S E D I M E N T

SAMPLE DATE: SEPTEMBER 9, 1976 SAMPLE LOCATION: HAT ROCK (M-E) SAMPLING METHOD: PlSTON CORING

dlmh m

CORE DEPTH (cm) - 4 0 ~

0-10.2 38.7 10.2-20.3 20.3-30.5 30.5-40.6 40.6-50.8 50.8-61.0 61.0-71.1 40.1 71.1-81.3 81.3-91.4 91.4-101.6

101.6-111.8 111.8-121.9 121.9-132.1 39.8 132.1-142.2 142.2 -152.4 152.4-162.6 162.6-172.7 172.7-132.9 182.9-193.0 41.9 193.0-203.2 203.2-213.4 213.4-223.5 223.5 -233.7 233.7 -243.8 243.8-254.0 39.7 254.0-264.2 264.2-274.3 274.0-234.5 284.5-294.6 39.4

R A D I O N U C L I D E C O N C E N T R A T I O N S I N C O L U M B I A K I V E R S E D I M E N T

SAMPLE DATE: AUGUST 13, 1976 SAMPLE LOCATION: 1-112 MILES UPSTREAM FROM MCNARY DAM, OREGON S I DE (M-F) SAMPLING METHOD: GRAVITY CORING

CORE DEPTH (cm) - 40 K

0-5.1 37.2 5.1-7.6 7.6-10.2

10.2-12.7 12.7-15.2 15.2-17.9 17.8-20.3 37.1 20.3 -22.9 22.9 -25.4 25.4-27.9 27.9-30.5 30.5 -33.0 33.0-35.6 37.0 35.6-38.1 38.1-40.6 4Q6-43.2 43.2 -45.7 45.7-48.3 48.3 -50.8 38.2 50.8-53.5 53.5 -55.9 55.9-58.4 58.4 -60.0 37.7

dlm lg rn

137c 5 152-154Eu 228 226R, Th --

In 9 s s S 8 O d d d d d

l o '

L 2,

u 9 mcv In In In s z ~ ~ E s Q E a 3 s % ~ 3 ( V 9 3 s % ~ r - 9 9 9 ddddddddddo*o*o'driddddddddd v v v v v v v v v v v v v v v v v v v v v v v v

~ ~ % ~ s ~ ~ c z ~ ~ s ~ ~ s % % ~ ~ ~ ~ ~ a e M ( V N ( V d N ( V O d d N N N ( V I n M b N M d N d d d d d d d d d d d d d d d d d d d d d d d d d d d

v v v v v

&t; I -oE n J z W W - JJJ a a a E E S a a a

K A D I O N U C L I D E C O N C E N T R A T I O N S I N C O L U M B I A R I V E R S E D I M E N T

SAMPLE DATE: SEPTEMBER 9, 1976 SAMPLE LOCAT ION: McNARY, BOUY #3 (M-G SAMPLING METHOD: P I STON COK ING

d l m lq rn

COKE DEPTH (cm)

0-15.2 15.2-25.4 25.4 -35.6 35.6 -45.7 45.7 -55.9

m I 4

55.9 -66.0 P 66.0-76.2

76.2 -86.4 86.4-96.5 96.5-106.7

106.7-116.8 116.8-127.0 127.0-137.2 137.2-147.3 147.3 -157.4 157.4-167.6 167.6-177.8 177.8-188.0 188.0-198.1 198.1-208.3 208.3 -218.4

O ( r \ V \ d O I V \ G N Y \ Y \ O O ~ D N C O ~ C ( J N N ~ ~ ~ ~ O ~ ~ ~ % F NCr\OdO(u\ 0

N N N m C u d m b m a m m m m ~ m d d d d d d d o * d d d d d d A d A d d d v v v v v v v v v v v v v v v v v v v v

R A D I O N U C L I D E C O N C E N T R A T I O N S I N C O L U M B I A R I V E R S E D I M E N T

SAMPLE DATE: AUGUST 10, 1976 SAMPLE LOCATION: THE DALLES, DOWNSTREAM FROM RABBIT ISLAND IN -35' OF WATER (D-A) SAMPLING METHOD: GRAVITY COKING

COKE DEPTH (cm)

dlm lg rn

137cs 152-154Eu 228Th 226Ra 23Spu 239-240pu --- --- - - 241~rn

1.31 1.66 a910 5.50 1.40 1.59 2.28 6.14 3.48 10.1 3.23 7.99 2.60 4.57 0.823 5.18 4.16 7.46 5.10 11.6 9.15 22.2 8.29 19.9 6.25 11.8 0.891 5.54

a: Iff

W W - -J --I a a a z s s 646 V)vlvl

K A D I O N U C L I D E C O N C E N T R A T I O N S I N C O L U M B l A R I V E R S E D I M E N T

SAMPLE DATE: AUGUST 10, 1976 SAMPLE LOCATION: THE DALLES DAM, WASHINGTON SIDE BOAT BAS I N I N -25' OF WATER ( D C ) SAMPLING METHOD: GRAVITY CORING

dlmlgm

CORE DEPTH (cm)

R A D I O N U C L I D E CONCENTRATIONS I N C O L U M B I A H I VER S E D I M E N T

SAMPLE DATE: AUGUST 11, 1976 SAMPLE LOCATION: STEVENSON, WASHINGTON, OFF CEMETERY IN--20'OFWATER (B-A1 SAMPLING METHOD: GRAVITY CORING

COKE DEPTH (cm)

0-2.5 2.5-5.1 5.1-7.6 7.6-10.2

10.2-12.7 12.7-15.2 15.2 -17.8 17.5 -20.3 20.3-22.9 22.9-25.4 25.4-27.9 27.9-30.5 30.5 -34.3 34.3 -39.4

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v Argonne, I L 60439 -- ONSITE

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Envi ronmental Research Washington, DC 20545 0. J. E l g e r t

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