P. 1 

# PICK-U P DATE : 3/15/200 7 BO X O F 

# 3 0 Step2 : FO RASR C INTERNA

L US E ONLY 

### (PARTB o

fB )



# EP ADOCKE TID : 102RQ-R N 1 ) 102RQ-RN-5-1 6 3 ) 102RQ-RN-5-1 8 5 ) 102RQ-RN-5-2 0 7 ) 102RQ-RN-5-2 2 9 ) 102RQ-RN-5-2 4 11 ) 102RQ-RN-5-2 6 13) (g2RQ-RN-5-2iT ) 15 ) 102RQ-RN-5-3 0 17) 102RQ-RN-6- 1 19 ) 102RQ-RN-6- 3 21 ) 102RQ-RN-6- 5 23 ) 102RQ-RN-6- 7 25 ) 102RQ-RN-6- 9 27 ) 102RQ-RN-6-1 1 29 ) 102RQ-RN-6-1 3 31 ) 102RQ-RN-6-1 5 33 ) 102RQ-RN-6-1 7 35 ) 102RQ-RN-6-1 9 37 ) 102RQ-RN-6-2 1 39 ) 102RQ-RN-6-2 3 Ste p 3 : FOR ASR C INTERNA LUS E ONL Y 

### CD : OA : / 

# 2 ) 102RQ-RN-5-1 7 4 ) 102RQ-RN-5-1 9 6 ) 102RQ-RN-5-2 1 8 ) 102RQ-RN-5-2 3 10) 102RQ-RN-5-2 5 12 ) 102RQ-RN-5-2 7 14) 102RQ-RN-5-2 9 16 ) 102RQ-RN-5-3 2 18 ) 102RQ-RN-6- 2 20 ) 102RQ-RN-6- 4 22 ) 102RQ-RN-6- 6 24 ) 102RQ-RN-6- 8 26 ) 102RQ-RN-6-1 0 28 ) 102RQ-RN-6-1 2 30 ) 102RQ-RN-6-1 4 32 ) 102RQ-RN-6-1 6 34 ) 102RQ-RN-6-1 8 36 ) 102RQ-RN-6-2 0 38 ) 102RQ-RN-6-2 2 40 ) 102RQ-RN-6-2 4

Ste p 1 : FO R ASR

C INTERNA LUS E ONL Y^^.^ Are ther e more documents fo rthi s Docke t i n anothe rbox ? *YE S f NO) *Fil l ou t Continuatio n Shee t an d go t o Ste p 2 — Interna l SFUN D Bo

xNumbe r_3 6 O F _28 3 Initials/Date : LDS__ / 3-15-2007

_

# r p .


### NUREG/CR-358 5 

# De Minimis Wast e Impact s Analysi s Methodolog y

Manuscrip t Completed : Decembe r198 3 Dat e Published : Februar y198 4 Prepare d b y 0

. I

. Oztunali , Dame s & Moor e G

. W

. Roles , USNR C Dame s an d Moore 2 0 Haarle m Avenu e Whit e Plains , N Y1060 3 

### Prepare d fo r Divisio n o fWast e Managemen t Offic e o fNuclea rMateria l Safet yan d Safeguard s U.S . Nuclea rRegulatoryCommissio n Washington , D.C . 2055 5 NR C FI N B731 8P. 3

6. 0 POS T DISPOSA L IMPACT S Th e previou s chapter s considere dradiologica l impact s whic hwoul dresul t from transportin g d e minimi s wast e t o a treatmen t o r disposa l facilit y a s wel l a s th e impact s tha t coul dresul t a s par t o f operatin g th e wast e treatmen t o r disposa l facility . Thi s chapte r addresse s th e potentia l radiologica l impact s tha t coul doccu r lon g afte r th e wast e ha s bee n dispose dint o th e ground . I nthi s chapter , thre e set s o f generi c sce nario s fo r huma nexposur e are considered , including : 1 . "Intrusio nscenarios " involvin g huma nintrusio nint o th e waste ; 2 . "Groundwate r scenarios " involvin g groundwate r migratio nand leachat e accumulation ; an d 3 . "Expose dwast e scenarios " i nwhic hdispose dwast e i s assume d t o be brough t t o th e surfac e an di s disperse db

y win do r water . Impact s calculate dfo r th e firs t se t o f scenario s (th e intrusio nscena rios ) depen dupo nth e concentration s o f th e radionuclide s withi nth e d e minimi s wast e stream s considered . Impact s calculate dfo r th e las t tw o set s o f scenario s depen dupo nth e tota l radionuclid e inventor y an dwast e volum e dispose da t th e disposa l site . A brie f overvie w

o f th e post-disposa l exposur e scenario s considere di n thi s repor t i s presente di nSectio n6.1 , followe db y Section s 6. 2 throug h 6.4 , whic hdiscus s th e calculationa l procedure s fo r thes e scenario s i n mor e detail , an daddres s intrusio nscenarios , groundwate r andleachat e accunulatio nscenarios , an dexpose dwast e scenarios , respectively .
6. 1 Overvie w A s addresse di nth e followin g sections , th e calculationa l procedure s and assume dparamete r value s var y fo r th e differen t exposur e scenario s dependin g upo nth e followin g considerations :
o th e desig nandoperatio no f th e particula r disposa l facility ; o th e environmen t i nwhic hth e disposa l facilit y i s located ; and o th e wast e for

m an dpackagin g characteristic s o f th e d e minimi s wast e stream . Fiv e differen t disposa l facilitie s ar e considere di nthi s report , andany on e ma y be considere db

y th e use r o f th e compute r codes . Thes e includ e a n on-sit e disposa l facility , tw o disposa l facilitie s fo r municipa l waste , andtwo disposa l facilitie s fo r hazardou s waste . Paramete r value s fo r th e on-sit e disposa l facilit y mus t b e supplie db y th e use r o f th e code , sinc e th e on-sit e facilit y ma y b e o f any

siz e o r configuration . Fo r th e othe r fou r facilitie s referenc e sit e paramete r value s ar e assume di nth e compute r code s a s discusse di nth e appropriat e section s o f th e report . I n addition , thre e referenc e disposa l sit e environment s ar e considere di n thi s report , an

dth e use r o f th e cod e ma y specif y

th e particula r environ men t t o b e considered . Th e scenario s an dcalculationa l procedure s ar e discusse di nterm s o f th e abov e considerations . 

### 6- 1P. 4

Afte rcalculatin q th e averag e rado n qa s concentratio n (C ) withi n th e buildino , annua l imoact s ar e determine d as :
H = £C ED

F PDCF-3 (6-18 ) n wher e H i s i n mrem/.y ran d C i s a s discusse d above

. Th e exposur e duratio n factor , EDF , i s obtaine d fro m th e assume d activit ydistributio n presente d a t th e beginnin g o fthi s sectio n fo rth e individua l intrude r(i.e. , ED F = 4380/876 0 = 0.5)

. PDCF- 3 i s th e appropriat e pathwa ydos e conversio n facto rfo rradon-222

. Impact s ar e summe d ove ral l wast e stream s con tainin n radium-22 6 a t th e tim e tha tth e intrude rscenari o i s initiated , an d adde d t. o th e othe rimpact s calculate d fo rth e intruder-agricultur e scenario

. 6. 3 Groundwate rScenario s Thes e scenario s calculat e th e potentia l impact s resultin g fro m qroundwate r migratio n o fradionuclide s fro m th e dispose d waste s t o thre e biot a acces s location s downstrea m i n th e directio n o fth e groundwate rflow : (1 ) a wel l locate d a tth e boundar yo fth e disposa l area , (2 ) a wel l locate d betwee n th e disposa l facilit yan d th e surfac e hydrologi cboundary , an d (3 ) a strea m locate d a t th e surfac e hydrologi cboundary

. Different , pathwa ydos e conversio n factor s ar e use d dependin g o n whethe rth e acces s locatio n i s a wel l o ra strea m (se e Appendi xD)

. An idealize d ma p showin g th e qeometri c relationship s hetwee n th e disposa l facilit yan d th e biot a acces s location s i s show n a s Figur e 6.3

. As show n i n thi s figure , th e mai n streamlin e passin g underneat h th e disposa l facilit yha s bee n straightene d ou t (th e longitudina l coordinate s ar e measure d alon g thi s streamline)

. Th e overal l are a o fth e disposa l facility , whic h influence s th e migratio n calculations , varie s dependin g upo n th e particula rfacilit yconsidered

. Fo rmunicipa l wast e disposa l (eithe ra sanitar ylandfil l o ra n ope n dump) , th e disposa l are a cover s approximatel y30 0 m b y34 0 m , whil e fo rhazardou s wast e disposal , th e disposa l are a cover s approximatel y66 5 m by91 0 m . Fo ron-sit e disposal , th e disposa l are a dimension s (e.g. , lengt h an d widt h correspondin g t o th e abov e 30 0 m an d 34 0 m ) ar e specifie d b

yth e use ro fth e code

. I t ma yals o b e observe d tha t th e disposa l are a i n Figur e 6. 3 ha s bee n divide d int o 1 0 sectors

. I n th e calculation , th e tota l radionuclid e auantit ydispose d i n th e disposa l sit e i s divide d by10 , an d th e resultan ttent h i s assume d t o h e release d a s a poin tsourc e int o eac h sector

. Th e tota l impact s fro m mioratio n fro m eac h poin t sourc e ar e summed

. Th e followin g equatio n i s use d t o calculat e huma n exposure s whic h ma yresul tfro m th e wel l acces s Groundwate rscenarios : 

### H « I Z VdiVifs i C i n 

### PDCF- 6 (6-19 ) i n 6-1 8O l

I 1 0DTH

•3-

• | —

X o 

### ¥ —> X 1

.ENGT H


### IIII I DI[SP0SAL_AREA 1 X X X X

u\ I I —> X X X 

## I

vrJ-1> INDIVIDUAL-WEL L POPULATION-WEL L

MAI N STREAMLIN E POPULATION-SURFAC E WATE R

GROUNDWATE RFLOW DIRECTIO N SIT F BOUNDAR Y KEY : XSOURCE S 0 ACCES S LOCATION S



# GEOMETRI C RELATIONSHIP S O F DISPOSA LARE AAN D DISCHARG E LOCATION S

FIGUR E 6. 3P. 6

wher e H i s th e annua l dos e rat e i n mre m pe ryea rdurin g th e 50tH n ^peai ro f exposure , PDCF-6 i s th e radionuc l ide-specifi cpathwa ydos e c o Rimer s lio n facto rdiscusse d an d presente d i n Appendi xD , Ci n i s th e concentration! , o f th e radionuclid e i n th e d e minimi s wast e strea m considered , 1 <dlem.ot.e s summatio n ove ral l th e d e minimi s wast e streams , an d n denote s stumnratno n ove ral l th e radionuclides

. (Not e th e differenc e betwee n th e caimceimtira
tio n C-j n an d th e concentratio n C wconsidere d i n th e intrusio n sceui.ain.os. ) Fo ra surfac e wate racces s locatio n th e dos e conversio n facto rPBECF- 7 i s substitute d instea d o fPDCF-6

. Th e value s o fth e transfe rfactor s are presente d below

. Th e tim e dela yfacto rf 0 an d th e sit e desig n an d operatio n facto rff<gfar e assume d t o b e unity

. Thi s merel ymean s tha tth e groundwate rnmiigratior i scenari o i s assume d t o b e initate d a tth e clos e o fth e operational ! [perio d an d tha t th e influenc e o n th e calculation s resultin g fro m design * o fth e disposa l facilit yi s considere d a s par to fth e wast e for m airo< 8 pe.cfec.g e facto ran d th e sit e selectio n factor

. I t i s als o importan t t o recogniz e tha t du e t o certai n aspect s of fth e disposa l facilitie s an d sit e environment s considere d i n thi s report, , som e judgemen t i s require d b yth e cod e use ri n interpretin g result s of fgroun d wate rmigratio n calculations

. Th e groun d wate rmigratio n calcuuTattften s depen d upo n a n assumptio n tha tth e rat e o fwate rpercolatin g tUnrouiigK n th e disposa l cel l cover s i s les s tha n th e rat e o fwate rinfiltratin g ouu t th e botto m o fth e disposa l cells

. I fnot , the n th e percolatin g waite rca n accumulat e withi n th e disposa l cell s as leachate

. Thi s ca n hapipem , fo r example , a t a disposa l facilit ylocate d a t a humi d sit e hawiirai g wer y impermeabl e soil s (o ra n impermeabl e liner) , an d th e permeabilit yof fth e disposa l cel l cover s exceed s tha t o fth e soi l (o rliner)

. It. this cas e impact s associate d wit h thi s leachat e accumulatio n woul d b e mor e ffi|ppn!D[!i.riat e t o conside rtha n thos e associate d wit h groun d wate rmigratiiomi
- Tffeese leachat e accumulatio n impact s ar e addresse d i n Sectio n 6.3.3

. 6.3. 1 Sourc e Ter m Th e sourc e ter m i s represente d b yth e wast e for m an d packag e facto rff

. , whic h ha s unit s o fm^/year , an d whic h denote s th e annua l woilutnrae ' o f contaminate d liqui d tha tpasse s int o th e aquife rbeneat h th e «ii'ris|pxosa l facility

. Thi s facto ri s give n byth e formula :
fw i = U V wf c , (((&-20 )
wher e f- j i s th e fractio n o fth e tota l dispose d wast e volum e (<dt e rmiinnii,mis plu s non-radioactiv e waste ) tha t comprise s th e (i) t n d e miraiirmii s wast e stream ; V wi s th e annua l volum e o fwate rtha tpercolate s tHi.(rau# i th e disposa l facilit ycove ran d contact s th e dispose d waste/soi l mixtiumae^ -an d f ci s th e fractio n o fth e wast e radionuclid e concentratio n traiusffenra d t o th e leachate

.


### 6-2 0P. 7

Th e firs t facto rf- j i s self-evident ; i t i s th e rati o o fth e volum e o fth e d e minimi s wast e strea m bein g considere d t o th e entir e volum e o fwast e disposed

. Clearly , th e variabl e (V w ) i s simpl yth e percolatin g infiTi
tratio n (p ) multiplie d b yth e effectiv e disposa l sit e surfac e are a (Sf} , whic h i s th e surfac e are a o fth e disposa l cells

. (Th e spac e betwee n th e disposa l cells , i fany , i s no t included)

. Th e effectiv e disposa l sit e surfac e are a i s give n a s follows :
S f= V t o t /

(EM P xEFF) (6-21 ) wher e ^to t = tota l volum e o fwast e (d e minimi s an d othe rwaste ) dispose d a t

th e site , i n m^ ; EM P = wast e emplacemen tefficienc y(dimensionless ) whic h i s define d t o b e volum e o fwast e emplace d i n th e disposa l cell s divide d byth e tota l volum e o favailabl e disposa l space ; an d EF F = volumetri cdisposa l efficienc y(i n m) whic h i s define d t o b e th e volum e o favailabl e disposa l spac e i n a disposa l cel l divide d b yth e surfac e are a o fth e disposa l cell

. I n th e abov e equation , al l thre e parameter s ar e supplie d b yth e use rfo r on-sit e disposal

. Fo rmunicipa l (sanitar ylandfil l an d ope n dump ) an d hazardou s wast e disposa l V^0 - t i s th e averag e annua l wast e volum e time s th e operatin g life , whic h i s assume d t o b e 2 0 years . Referenc e parameter s fo r municipa l an d hazardou s wast e disposa l facilitie s ar e show n i n Tabl e 6-4

.

TABLE 6- 4

. Referenc e Disposa l Parameter s

Municipa l Hazardou s Paramete rWast e Facilit yMast e Facilit y V t o t ( m3 ) 592,00 0 1,827,00 0 EM P 0. 8 0.7 5 EFF (m ) 7.3 1 4.3 7

Ther e ma

ybe
- severa l differen ttechnique s fo rcalculatin g th e paramete r (p ) (als o calle d PER C i n severa l references)

. On e o fthes e method s i s usuall ycalle d th e water-balanc e techniqu e (Refs

. 8 an d 9 - als o se e Appendi xC)

. Th e water-balanc e techniqu e yield s percolatio n component s o f abou t 7 4 m

m o fwate rpe ryea rfo rth e northeas t site , 18 0 m m o fwate rpe r yea rfo rth e southeas t site , an d 1 m m o fwate rpe ryea rfo rth e southwes t site

. Thes e value s ar e applicabl e t o surfac e condition s a t th e sit e prio r t o constructio n an d operatio n o fa disposa l facility

. Th e volum e o fwate r percolatin g i n thi s cas e wil l b e denote d b yVI

. 

### 6-2 1P. 8

Fo r case s wher e ther e exist s specia l disposa l facilit y cover s containin g lo w permeabilit y

layers , an dwher e th e integrit y o f th e cover s ca nb e assumed , the percolatio ncomponen t may b e determine db

y the Darc y

velocit y o f the leas t permeabl e stratu m betwee nth e wast e an dth e atmospher e (Ref . 10) . Th e Darc y

velocit y

o f a material , wit hhydrauli c conductivit y (K ) i n unit s o f m/y r an

duni t hydrauli c gradien t (th e mos t conservativ e assump tion) , i s equa l t o Km 3 /m 2 -yr . Thi s number , however , shoul db e modifie db y the fractio no f eac hyea r durin a whic hther e i s a t leas t 0.0 1 inc ho f precipitation . Therefore , inthi s latte r case , (p ) wil l be calculate dfrom th e followin o eouation :

p= K(w/365 ) (6-22 )
wher e (K ) i s th e hydrauli cconductivit yo fth e leas tpermeabl e laye r coverin g th e waste , an d (w ) i s th e mean annua l numbe ro fday s wit h 0.0 1 inc h o rmore o frainfal l (se e Referenc e 10)

. Assumin g tha ta permeabilit y o f3xl0" 7 cm/se c(abou t 0. 3 ft/yr ) i s applicabl e fo rth e leas tpermeabl e stratu m o fth e disposa l facilit ycover , an d assumin g appropriat e value s f o rwfo reac h o fth e referenc e sites , thi s yield s estimate d percolatio n component s o f3 6 mm , 3 0 m m an d 1 mm , respectively , fo rth e northeast , southeas t an d wester n sites

. Th e volum e o fwate rpercolatin g i n thi s cas e wil l b e denote d b yV2

. Th e specifi cpercolatio n valu e use d i n th e calculation s depend s upo n th e particula rdisposa l facilitie s considered

. Fo ron-sit e disposal , p i s supplie d b yth e use ro fth e code

. Fo rmunicipa l wast e disposal , p varie s dependin g upo n whethe ron e i s considerin g a sanitar ylandfil l o ra n ope, n dump

. Fo ra sanitar ylandfill , p i s assume d t o b e equa l t o V I whil e fo r a n ope n dump , D i s assume d t o b e equa l t o 2V1

. Thi s basicall yassume s tha t i n a well-operate d sanitar ylandfill , percolatio n int o th e sit e wil l b e n o large rtha n tha twhic h existe d prio rt o constructio n o fth e disposa l facility

. A n ope n dum p i s assume d t o b e operate d i n a much les s satis
- factor ymanne rtha n a sanitar ylandfill , includin g poo rcompactio n o fth e waste , a n inadequate , poorl ycompacte d fina l cover , an d failur e t o perfor m maintenanc e activitie s suc h a s repai ro fsubsidenc e depressions

. Thi s result s i n increase d percolatio n int o th e waste , (th e ope n dum p i s assume d t o b e characterize d b ypothole s an d subsidenc e depressions , resultin g i n concentrate d source s o frai n wate rinfiltration)

. Tw o optiona l value s fo rth e percolatio n ar e als o availabl e fo rth e hazardou s wast e facility--!'.e. , th e use ro fth e cod e ma yselec t a percola
tio n valu e eaua l t o eithe rV 2 o rVI

. Th e forme rcoul d represen t a possibl e cas e i n whic h th e syntheti cmembran e i n th e disposa l cel l cover s fai l t o functio n a s expecte d (perhap s du e t o damage) , an d rainwate r percolate s throug h th e compacte d cla ylaye rbeneat h th e syntheti cmem brane

. (Se e Section s 5.5. 1 an d C.4. 2 fo ra descriptio n o fth e hazardou s wast e facilit ydesign)

. Thelatte rcoul d possibl yrepresen ta sit * operatin g unde rinteri m statu s standard s (Se e Sectio n C.4.2)

. Unlik e ti e ope n dump , however , al l hazardou s wast e facilitie s ar e assume d t o b e operate d i n a reasonabl e manner . 6-2 2P. 9



### Th e facto r f c 

### represent s the fractio no f the activit y tha t i s transferre d fro m the wast e t o th e leachate . I t may be calculate dusin o the followin g formula : f c 

### = M 0 

### t c 

### 10d-IA ) (6-23 )
wher e M 0 i s th e fractio n o fa specifi cradionuclid e transferre d fro m dispose d wast e t o trenc h leachat e du e t o contac t o fwate ra tcontinuou s ful l saturation ; t ci s th e fractio n o fa yea rtha t th e infiltratin a volum e o fwate ri s i n contac twit h th e waste ; an d th e facto r10 ^ 1-IA > *j sth e accessibilit ymultiplie r(se e Sectio n 2.2.4)

. Thes e ar e discusse d below

. Th e facto rM 0 ca n b e estimate d b yman ymethods

. I n thi s report , th e averag e uppe rbound s o fth e leac h fractio n ar e estimate d assumin g tha t th e leachate/wast e condition s a tth e Maxe yFlat s disposa l facilit yma yb e use d t o approximat e thi s boundin g fraction

. A s discusse d extensivel yi n Referenc e 1 , radionuclid e concentration s i n leachat e wer e obtaine d fro m leachat e sample s obtaine d fro m severa l disposa l trenches

. Thes e radio
- nuclid e concentration s wer e the n ratioe d t o th e radionuclid e concentra tion s i n th e wast e dispose d i n th e disposa l trenches

. Th e ratio s obtaine d fro m eac h trenc h wer e the n average d ove ral l trenche s sampled

. Th e ratio s thu s obtaine d ar e liste d i n Tabl e 6-5

. Th e primar yrational e fo rthi s approac h i s tha t unde rspecifie d chemica l condition s ther e i s a n uppe rlimi t t o th e solubilit yo fal l elements

. Th e abov e disposa l site , becaus e o fth e presenc e o forgani cchemical s an d chelatin g agent s an d becaus e wast e trenche s ca n b e assume d t o b e a t continuou s ful l saturation , ma yb e assume d t o represen textrem e leach
abilit yconditions

. Thi s estimat e als o take s int o consideratio n th e fractio n o fth e leache d radioactivit ytha tma yb e reversibl yadsorbe d b y th e interstitia l trenc h soils

. Som e researcher s believ e that , us e o fMaxey Flat s estimate s represen t th e bes t tha t ca n b e achieve d wit h th e availabl e experimenta l dat a (Ref

. 4)

. Th e us e o fth e facto rM 0 , however , necessitate s a correctio n facto rt o tak e int o accoun t th e expecte d transien tan d partiall ysaturate d condi
tions

. Thi s correctio n facto ri s approximate d throug h t c . Thi s fractio n depend s o n th e contac t tim e betwee n th e wast e an d infiltratin g water

. Assumin g tha t leachin g a tpartia l saturatio n i s proportiona l t o th e moistur e content , th e fractio n (t c ) ma yb e expresse d a s th e fractio n o fa yea rtha t th e percolatio n componen tcalculate d abov e take s t o pas s throug h a aive n horizonta l plane , i.e. , t c= p/(nv ) (6-24 )
wher e p i s th e precipitatio n (i n m/yr ) tha tinfiltrate s an d come s int o contac t wit h th e waste , n i s th e wast e cel l effectiv e porosity , an d vi s th e spee d o fth e percolatin g wate r(i n m/yr)

. Th e wast e cel l effectiv e 

### 6-2 3P.1 0

TABL E 6- 5 . Radionuclid e Partitio n Ratio s

Betwee n Wast e an

d Leachat e

Elemen t 

### H * C * N a 

### P S C l C a S c C r M n F e 

### Co * N i Z n S e R b 

### Sr * Z r N b M o T c R u Rati o

1.15E+0* * 5.76E- 3 1.62E- 4 1.26E- 3 1.20E- 2 1.15E- 1 9.86E- 3 1.11E- 4 1.26E- 3 1.26E- 3 1.48E- 2 1.48E- 2 1.48E- 2 1.48E- 2 1.20E- 2 1.62E- 4 9.86E- 3 9.86E- 3 1.11E- 2 1.15E- 1 1.15E- 1 1.15E- 1 Elemen t



### A a C d S n S b 

### I Cs * B a L a C e E u Y b P b P o R a A c T h P a U* N p 

### Pu * Am* C m Cf Rati o

1.62E- 4 1.48E- 2 1.62E- 4 1.62E- 4 1.15E- 1 1.62E- 4 1.11E- 4 1.11E- 4 4.67E- 4 1.11E- 4 1.11E- 4 4.11E- 3 4.11E- 3 4.11E- 3 4.11E- 3 4.11E- 3 4.11E- 3 1.25E- 4 4.67E- 4 4.67E- 4 4.11E- 3 4.67E- 4 4.11E- 3

* Thes e ratio s ar e obtaine d fro mReferenc e 3 , an

d wer e calculate d base d on experimenta l data
. Th e remaining ratio s ar e estimate d base d on chemica l similaritie s betwee n nuclides
.
* * Exponentia l notation , i.e. , 1.15E+0=1.15xlO +0

.

6-2 4P.1 1

porosit y

ca nconservativel y b e assume dt o b e abou t 25 % (partiall y com pacte dsoil s ar e likel y t o hav e highe r porositie s resultin g i nlowe r contac t times) . Th e valu e o f v depend s onth e interstitia l soils ; a ^ery conservativel y

lo w valu e o f 1 ft/da y

(correspondin g t o a permeabilit y o f abou t lxlO-^cm/sec) , a neffectiv e porosit y o f 0.25 , an da hydrauli c gradien t o f unit y wil l b e assume dinthi s report . Th e value s fo r t c fo r eac ho f th e referenc e site s ar e presente di nTabl e 6-6 . (The contac t tim e fractio nfo r th e on-sit e facilit y i s specifie db

y th e use r o f th e codes. )

TABL E 6- 6 . Value s o f Contac t Time Fractio n

Northeas t Southeas t Southwes t Volume o f Wate r



### V I 2 V I 2.66xl0~ 3 5.39xl0- 3 6.47xl0- 3 1.29x10- 3 3.60xl0- 5 7.19x10- 3 

### V 2 1.29x10- 3 1.08x10- 3 3.60xl0- 5

It shoul dbe note dtha t a nincreas e o r decreas e i nth e volume o f percolat ing wate r affect s th e contac t tim e linearly , whic hi s furthe r incorporate d int o th e formulatio no f th e sourc e term f w -j . Therefore , th e sourc e term i s a quadrati c functio no f percolation . I t shoul dals o b e note dtha t th e contac t tim e fractio napproximatio nshoul donl y b e considere dreasonabl e ove r a relativel y

smal l rang e o f percolatin g wate r speeds . Us e o f th e contac t tim e fractio nals o implie s tha t th e dispose dwast e i s no t i n continuou s ful l saturation . Th e las t facto r i nequatio n(6-23) , lo ( 1-IA) , i s th e multiplie r du e t o th e relativ e inaccessibilit y o f radioactivit y

i nactivate dmetal s wast e streams . Th e multiplie r fo r activate dmeta l wast e form s ha s bee ndiscusse d i nSectio n2.2.4 . Us e o f th e accessibilit y facto r i nth e estimate s o f th e groundwate r migratio nsourc e term i s discusse di nReferenc e 1 . 6.3. 2 Migratio nReductio nFacto r Th e wast e for m

an dpackag e factor , a s expresse dabove , yield s th e tota l sourc e ter m

(i nnr/yr ) tha t canb e expecte dfro m a give nd e minimi s wast e stream , andth e produc t o f th e radioactiv e concentratio nwit hth e sourc e ter m give s th e annua l releas e (i nCi/yr) . Thi s sourc e ter m mus t b e relate dt o th e radionuclid e concentration s a t th e groundwate r biot a acces s locations . Thi s relatio ni s expresse dthroug hth e sit e selectio nfacto r (f s ) i nunit s o f yr/m 3 . Thi s factor , whic hha s als o bee nreference da s th e "confinemen t factor " o r "reductio nfactor " (Ref . 1) , i s th e groun dwate r migratio nanalo g o f th e (X/Q ) dispersio nfacto r i nmeteorologica l diffu sio ncalculations .

6-2 5P.1 2

I n thi s report , a variatio n o fth e migratio n mode l utilize d i n th e EIS' s i n suppor t o fth e Par t 6 1 rul e i s use d (Refs

. 11 , 12)

. Thi s mode l assume s tha t th e porou s mediu m consist s o fa n unsaturate d an d a saturate d zone , eac h o fwhic h i s stationary , homogeneou s an d isotropic , an d th e flui d movin g throug h thes e zone s i s incompressibl e an d o fconstan tviscosity

. Als o ver yimportantly , us e o fthi s mode l assume s tha t an yliner s place d beneat h th e disposa l facilitie s ar e non-functional , o ra t leas t onl y partl yfunctional

. Hazardou s wast e facilitie s ar e require d b yEP A regulatio n t o instal l liners , bu t t o dat e ther e i s littl e dat a regardin g thei roveral l effectiveness

. Similarly , sanitar ylandfill s ma yo rma yno t incorporat e liners , an d lik e liner s fo rhazardou s wast e facilities , onl y tim e an d accumulate d experienc e wil l demonstrat e thei reffectiveness

. Th e on-sit e disposa l facilit yan d ope n dum p wil l probabl yno t hav e liner s installe d i n an ycase . Th e sourc e ter m i s assume d t o b e give n b yJ 0 (whic h i s equa l t o f wl multiplie d byth e wast e radionuclid e concentrations) , whos e unit s ar e i n Ci/yr

. Th e sourc e ter m i s assume d t o exis tdurin g th e sourc e duratio n tim e (T)

. Ageometr yo fth e migratio n proble m i s show n i n Figur e 6.4

. Th e measurabl e hydrogeologica l parameter s tha t mus tb e include d i n a simulatio n o fmass transpor t are: th e geometr yo fth e proble m (e.g. , th e trave l distance , x , t o a biot a acces s location) , th e hydrauli cvelocitie s o fth e flui d (e.g. , v) , th e dispersio n characteristic s o fth e medium , an d th e retardatio n coefficient s o fth e soil s throug h whic h radionuclide s ar e migrating

. Th e space - an d time-averagin g o fth e abov e parameters , i f necessary , ma

yb e accomplishe d i n a straightforwar d manne r(se e Ref

. 1)

. A s discusse d i n Sectio n 6.1 , i tca n b e show n tha tth e tim e dependen t sit e selectio n facto ri s give n by(Ref

. 1) : U, = f> g /Q ] £r t i j (6-25 )

J wher e (Q ) i s th e dilutio n facto ri n unit s o fvolume/time ; th e facto rr g i s th e time-independen t reductio n facto rdu e t o th e geometr yo fth e proble m (i.e. , th e spatia l relationshi p o fth e disposa l facilit yan d th e biot a acces s location) ; j denote s th e longitudina l sector s o fth e disposa l facilit yshow n i n Figur e 6.3 ; an d r-tj j i s th e reductio n facto rdu e t o migratio n an d radioactiv e deca ywhic h depend s o n bot h spac e an d time , includin g th e sector s o fth e disposa l facilit yan d th e sourc e duratio n tim e (T)

. Geometri cReductio n Facto r- r g Thi s reductio n facto ri s assume d t o b e independen to fth e characteristic s o fth e wast e streams

. I ti s als o independen to fth e longitudina l relation
- shi p o fth e disposa l facilit ywit h th e biot a acces s location

. I n thi s report , i t i s conservativel yassume d tha t th e geometri creductio n facto r r g i s it s maximu m value , unity

. 6-2 6r

o UNSATURATEDZON E PARAMETERS : w , z 0 , R u D uD uD u J 0 (x",y",t" ) BOTTO M OF THE DISPOSA L CELL

HYDRAULI C VELOCITY 

## M

STREAMLIN E

HYDRAULI C VELOCITY(v )

SATURATEDZON

E PARAMETERS : V , X , R s , D s n s n s INTERFACE O F THE SATURATEDAN

D UNSATURATEDZONE S

J(x,t )

DISCHARGE SURFAC E



# GEOMETR YO F GROUNDWATE R MIGRATIO N
FIGUR E 6, 4
T

_P.1 4

Dilutio nFacto r - 0 Th e dilutio nfacto r i s independen t o f th e characteristic s o f th e wast e stream an dth e geometrica l relationshi po f th e disposa l facilit y wit h respec t t o acces s location . Th e facto r Q may be th e pumpin g rat e o f a wel l o r th e flo

w rat e o f a stream . I nthi s work , th e dilutio nrate s assume dar e 200,00 0 nvVyea r (abou t 10 0 go m - gallon s pe r minute ) fo r th e populatio nwel l scenari o an d4. 5 x10 ° n.3/yea r (abou t 5 cf s - cubi c fee t pe r second ) fo r th e surfac e stream scenario . Smal l farmin g communitie s tha t utiliz e groundwate r fo r thei r need s usuall y

hav e well s tha t rang e fro m 10 0 gp m t o 100 0 gp

m dependin g o

n th e population . A

stream flo w rat e o f abou t 5 cf s i s selecte dsinc e a strea m wit hflo w

rat e belo w

thi s valu e i s very unlikel y

t o be use dfo r huma nconsumption . Fo r example , Roc kLic kCree knearb y th e Maxe y

Flat s disposa l facilit y ha s anannua l averag e flow rat e o f abou t 7 cfs , bu t i t i s no t use dfo r huma nconsumption ; i t i s use donl y fo r livestock . For ' th e intrude r wel l scenario , Q i s give nb y th e assume dtota l volume o f precipitatio ninfjltratin g throug hth e disposa l facilit y are a unde r natura l sit e conditions . Inothe r words , th e sourc e term , J 0 , calculate d i nth e previou s sectio ni s dilute db y a minimu m

volum e o f wate r (infil tratin g throug hth e disoosa l are a andrechargin o th e groundwater ) equa l t o th e product , o f th e sit e percolatio n(VI ) wit hth e tota l surfac e are a o f th e disposa l facility . Th e tota l surfac e are a consist s o f th e surfac e are a o f th e disposa l cell s plus any spac e betwee nth e disposa l cells . I t i s calculate dby

dividin g th e effectiv e surfac e are a (define di nSectio n 6.3.1 ) b

y th e surfac e utilizatio nefficienc y (SEFF) , wher e SEF F i s define d a s th e rati o o f th e surfac e are a o f th e disposa l cell s t o th e surfac e are a o f th e disposa l cell s plu s an y spac e betwee nth e disposa l cells . SEF F i s provide db

y th e cod e use r fo r on-sit e disposal , andi s assume dt o be unit y fo r municipa l wast e disposa l and0. 9 fo r hazardou s wast e disposal . Ther e i s a lowe r bound , however , fo r th e valu e o f th e dilutio nvolume fo r th e intrude r well . Otherwis e th e abov e techniqu e woul dgiv e invali d result s fo r disposa l facilitie s locate dinregiona l environment s i nwhic h th e natura l percolatio ni s low , e.g. , a semi-ari denvironment . Th e lowe r bounddilutio nrat e inthi s repor t i s take nt o be 770 0 m3/yea r (3.8 4 qpm) , whic hrepresent s th e ,minimum , practica l need s o f a singl e perso nlivin g i n a rura l are a (Ref . 3) . <•/* . < — N: I !)• £ y,,,. .,•>•.:,'>! Migratio nReductio nFacto r - rt-j-j Thi s facto r depend s o nth e time , afte r initiatio no f th e scenario , tha t th e exposur e i s assume dt o occur , th e duratio no f groundwate r trave l betwee nth e .i t nlongitudina l secto r makin g u pth e disposa l facilit y and th e biot a acces s location , th e retardatio ncapabilit y o f th e soil s (radionuclid e dependent) , th e duratio no f th e assume dsourc e term , andth e wast e stream

characteristics . Th e longitudina l exten t o f th e disposa l facilit y

i s considere db y dividin g th e facilit y int o 1 0 sector s an d summin g th e contribution s fro m eac hsecto r (assume dt o b e equa l i nsize )

6-2 8P.1 5

t o obtai n th e concentration s a tth e biot a acces s location

. I n thi s work , th e followin g formul a i s use d fo rth e migratio n reductio n facto rr-fjj :

r t 1 j = [exp(-Xt)/(JxT*j) ] x[ Fj(t ) - Fj(t-Ti ) ] (6-26 )

wher e Xi s th e deca y constan t o f th e radionuclide ; t i s th e tim e a t whic h th e migratio nreductio nfacto r i s applicable ; Ji s th e tota l numbe r o f longitudina l sector s th e disposa l sit e ha s bee ndivide dinto , whic hi s 1 0 i nthi s wor k(se e Figur e 6.3) ; T j i s th e sourc e duratio ntime fo r th e i t n d e minimi s wast e stream ; an dj denote s th e secto r o f th e disposa l site . Th e functio nFj(t ) i s give nb y th e followin g formul a (se e Refs . 1,2) : Fj(t ) = 0. 5 xU(t ) x[erfc(X_ ) + exp(Pj ) erfc(X+) ] (6-27 )

x+= 

## ^_J_±t/lRt^l

_ (6 

## . 28 ) 

## 2 Vt/(Rt wj 

## )

wher e U(t ) i s th e uni t impuls e functio n tha t i s zer o fo ra negativ e argumen t an d i s equa l t o unit yotherwise ; t W j i s th e wate rtrave l tim e betwee n th e disposa l secto rbein g considere d an d th e biot a acces s loca
- tion ; P j i s th e Pecle t numbe rfo rth e distanc e betwee n th e disposa l secto r an d th e biot a acces s location ; R i s th e retardatio n coefficien to fth e radionuclide ; an d erfc(x ) i s th e complemen to fth e erro rfunctio n an d i s give n byth e formul a (Ref

. 12) :
x erfc(x ) = 1 - /

(2/ir ) exp(-t 2 ) d t (6-29 ) / Th e retardatio ncoefficient s (R ) tha t ar e utilize di nth e abov e equation s depen donth e radionuclid e a s wel l a s th e geochemistr y o f th e soil s an d th e transportin g groundwater . The y ar e indicativ e o f th e reversibl e ion exchang e capabilit y o f th e soil s an

drepresen t th e rati o o f th e radionuc lid e velocitie s i nth e soi l t o th e groundwate r velocities . Th e catio n exchang e capacit y o f th e soil s i s a paramete r whic hca nb e use dt o estimat e th e retardatio ncoefficient s o f th e soils , sinc e retardatio n coefficient s ar e usuall y linearl y

dependen t o nth e catio nexchang e capacity . Fiv e optiona l set s o f retardatio ncoefficients , presente di n Tabl e 6-7 , ma y

b e selecte db

y th e use r o f th e code . Th e cla y

andminera l conten t o f th e soils , i nadditio nt o th e groundwate r chemistry , significantl y affect s th e retardatio ncapabilit y o f th e soils . Th e retardatio ncoefficient s give ni nTabl e 6- 7 spa nth e genera l rang e o f value s tha t ar e encountere di ngroundwate r migratio ncalculations . Th e firs t se t i s representativ e o f coefficient s fo r sandy soil s wit hlow

t o
6-2 9C O .-•o o I •—-11 0 | H O I I

O I I rococ o I r o OOOOU 1

rococ o i r o OOOOC M rococ o inno o o«— •o.—* o 1 10-- 4 o O 1 1 1 O-— I

— < O 1 O

i m 1 C M V O 1 \ o 1 v o -•OOOV O VOOOOO O I

ooo- o oooooo o i LOOOV O CM—CO*" . C O o o o*-

. v o UDOV O ^J ur>*— 4 i— i oor o

O J tz OJ -•OOO O VOVOVOO O OOOVO O OVOOOV O VOVOOVO O VOVOOVOV O OVOVOOV O .-4000 0 ooooo o

.*-ivooor - ta-Tt-ooo o unuouo-ej-r ^ vo-^-O O vc-a-v o --a - vo^r-t t ro^-*5j-ro*cj - oocor o ooooooo o orocor- 1 «^-.-4i_r>u D -"S-r—i-tj * r- i -i^-r-t^ H r-..—ir-41-*..— i inoisr* . r-or^oo o * > 3 IA Cm. -J e

. _) Q . E Z . O J « < D t o <_) !

_ Q > c o 4 - o O J JZ IA

r-l a-f CMC M in-**-* - **j-m><-_--mm m •—

i + J

•r - ^ Q ) O <_ ) C o • 1 — +• > IT S T. -. ' 0 *•- > O J Q

_ -o m) F = 3 l/ l 1/ ) < :

. i^ . i v o U J

_ j CQ < 1 — (I J

OO

r o +• > a . (• i

C M
+ J O J o o

r-l

•*-> O J o o

O J C J c a i ^ — I O >

- O • M C O J E O J •—oootv i mono o OOOCOC M ooooi n mmoco o oomoooo o ooooooo o T-ICMVO" * r-»f-.vov o ooON t CMI--O O CMI-*-C M r- - CMi^r-* . ONNO N r-.r o coc o -51-vov o r-

* O O r»« . r- » r- » C M C M LOC O c o o o ••ooo o ooooo o moo o ooooo o CMIOCMC M CMUDCMLOunif )

. . . ..... . CMr--t-- . r~-CMr^CMCMC M O Oj I

—sz

\

- m1/1 O <_*>•-- c o -i- Q L in T_ J 3 •* - E IA C O O •<- •l- J

_ • u •»-> r a Q J •o E i- O ro <_> E

TJ IAO J a i <T J

_ c t - +- > a > • o O J o J O E O H J ITJ

• o c u in 3

u >

HOOr- W-el-VOVOI^f ^ OOOVOI O OVOOO"-! - -steoio o VO^J-OVOV O OVOVOOV O --4000 0 ooooo o r-n_r>r-**C M cocoi^r - «d-mincoc M inco*!---* - inco m c o incoc > CMPOCOCMC O CMOCMC M CMOCMOO O CO.— I r-ir- 4 ior-.r- - c o vov o c o c o c o i n ur > .—iCMini n IDCMVOCMCMC M • I -v » z Q J O ro o >

HOCOf^i n COCOOOI^t ^ OOOCO" * COOOOOC O OOOOOOOOOO OOCOCOCOOO OOOCOOC O •—IOOO O ooooo o .— ir-.co<—•<—»<—4000 0 o^ivovo.—•>—

•r~.r-tini n r^r-ir»» . .— 4 i-*. . t . 4 CM.*-..—.CM.— i VOOCMC M CNJOCMOO O •— •CMCOO O •— i .—•.— i i—

i «— i r- 4 r ^ r- . vor^-i —r-vor-*-iovoi o

. . . . . ... . r- 4 CMC M 4— 4 r- 4 r-4.— . ,— 1 r- 4
r-ioincoc n CMO-JCTICOCO ooo<_ncr . mcr>ooc M cMCMincm n cr>cviino>CT > ocr>cr>oer > •—tooo o OOOOO O *-4C0*<- r**d"*tf

- COCMCM C

O O O 0 0 C O 0 0 «el -«tf " COOrf^ f<to«too o vo«a-» * o o o o o o oooooo cooooocococ o O J > T J •r - Q J m-> C I O -r- -. I D f O 4 J

. . . CLmZ. c u i n E o JL . i- 4 o u (U
m.

v o in*<3 - i n r- «

v o VO«3 - ooo o cococ o v o

•5 T V O 0 0

v o .

i n inc o in* * i»>.r r*c_

- mo o -ei-ooco-cj -

. .. . .... . . ... . .. . .... | r-4CM.--.rOC M ^-tCMCOCMC M CMCMCMCMC M ^HCM^-COC O VOCO^HCMC M COrHi-ICMO O COCMCMC M I •I O C M l« * I VOV O

voinu n VOLO--4--CJ -

... . I «a--ctcococ o I

r o i—

r. ij i- C Q JO-* - C O

l
_ Q J - »-___ ) O O 3 CT O C
_

Q ' 10 < n<f l Q J3_Q_ DO C ( 0 <JX

_I O Q- 3 I ___:OZQ.</ I out/xj z U.UZNI O o_:i^r->i___:s : t —a<ui/ ) t/)-—.<_>co_ < OUJS-O-Q . C__:O_:<C(—Q . oZQ- e ;E*» - _ o o •

= u z : c

« J - o •+ - . Q i

_ r 1 - o O I Q Jmi
ro ra > *->

_ Q ^ - o X > Q » C S r o -n j

i n O J C 0 0 r o • O 0 O

ir t ~3 O J c 4 J < 0 E ! C M <TJ i — ir t

• —•<- » E 0 J •r - I/ ) </ > r o -— > (_ > v o • c - r- 4 E Q > •

_ C <• - (_ ) a ; OC c — - o c • O E Q J 3 V) r— r o O J 3 O • a •»-

> 0 J -r E * 3 </ > i n «/ > «— r o -r O Q J t n 1

_ CO 4- >

• m- • a •«- > a » Q J c </ > • M Q J Q J • o E " O r —a » 3 r— i

_ O O J o r —<+ - r o O J O E <- 0 I O <— 4 > , IA r— O J 1 -<• - ( J •oo c t —Q J •r - IA \- E 0 J Q

J • I -O-lr M o a i n o •r - IA C •r —"r — i n i - c -!_ > C U 0 J OJ J = > W4Ji - o o> T 3 C J - Q J I O O I - <+ - i O -t IA IA 4-> O J T J C 3 CZ (U i— to -r— ra mi> r - l-i — i»

_< u IA**- IA •*- » Q J a j a i o r </ > o r — J 3 U 0 J

_ o 0 J > I O
Q J

O O

a i E • m i n a j 3 •l- > r— 3 - O O > X ) < o e n o

C O I IO

O i n m

• M E •r — < j c IT J •( - o . I O r— O f — < u « £ o > C Q . • O < — J C 0 J O J = X Q J O O 0 J •r - T 3 r o 3 O C7 >P.1 7



### moderat e catio nexchang e capacities , an di s assume dt o represen t the lowe r boundo f retardatio ncoefficient s usedi nthi s analysis . Th e fourt hse t i s representativ e o f coefficient s fo r claye y soil s wit hmoderat e t o high catio nexchang e capacities , an di s assume dt o represen t th e bes t con dition s tha t ca nb e routinel y achieved . Inbetwee nthes e tw o sets , tw

o othe r set s hav e beenpostulate dan dhav e bee ncalculate dutilizin gth e geometri c mid-point s o f set s 1 an d4 . A fift hse t o f coefficient s ha s bee nals o calculate dfo r us e i nspecia l cases . Any on e o f th e fiv e set s o f retardatio ncoefficient s may be selecte db

y the use r o f the cod e for a givensite . A s a reference , however , the thir d se t i s assume di nthi s repor t fo r the northeas t site , the secondse t fo r the southeas t site , an dthe firs t se t fo r the southwes t site . Th e choic e o f thes e thre e set s reflect s consideratio no f th e probabl e presenc e o f chelatin gagent s or organi c chemical s i nthe dispose dwaste . Th e sourc e duratio ntim e T j fo r th e i t n

### d e minimi s wast e strea m i s determine db

y dividin gthe tota l activit y i nth e strea m

wit hth e annua l releas e fractio nwhic hi s give nb y the facto r f w 

### * { multiplie db

y the radio nuclid e concentration . Thi s calculatio nconservativel y neglect s th e depletio no f th e radionuclid e inventor y a t th e disposa l facilit y b y previou s releases , an dresult s fro

m the manne r i nwhic hth e radionuclid e sourc e ter m

i s modeled . Tha t is , eac hyea r a fixe d"slug " o f activit y i s release dunti l the radionuclid e inventory i s deplete dafte r T- j years . No "exponential " sourc e term , i nwhic hth e fractio no f th e initia l sit e inventory

release deac hyea r i s exponentiall y reduced , i s considered . Th e groundwate r trave l time s t w 

### j depen do nth e distanc e betwee nth e disposa l facilit y

secto r beingconsidere dan dthe biot a acces s location . Th e trave l tim e betwee nwast e dispose di nthe firs t secto r an da biot a acces s locatio ni s denote db y t w 

### i , an di s give na s the su m o f the time reguire dt o travers e the unsaturate dzone wit hthe tim e require dt o mov e horizontall y

throughthe groundwate r t o the biot a acces s location . I t i s assume dfo r bot hthe northeas t andthe southeas t sites , fo r example , tha t groundwate r take s 1 0 year s verticall y t o travers e th e unsaturate dzone . th e assume dvalue s o f t ^ fo r the hazardou s andmunicipa l wast e disposa l facilitie s ar e presente di nTabl e 6- 8 fo r eac hreferenc e site . Th e qroundwate r trave l time betwee nthe cente r line s o f tw o adjacen t sector s i s als o show

ninTabl e 6-8 . T o determin e the groundwate r trave l time s t o biot a acces s location s fro m the othe r sectors , anappropriat e multipl e o f the trave l tim

e betwee nsector s i s adde dt o t^ . Th e groundwate r time s fo r th e sanitar y landfil l an dhazardou s wast e facilit y

ar e believe dt o be reflectiv e o f goodsit e selectio nprocedures , an dcorrespondt o groundwate r speed s o f 0. 2 m/y r fo r th e northeas t site , 1.2 5 m/y r fo r the southeas t site , an d1 0 m/y r fo r th e southwes t site . Th e opendump , however , i s assume dt o be site dina les s carefu l manner . Th e vertica l trave l tim e betwee nth e wast e an dth e groundwate r tabl e i s assume dt o be zer o fo r bot hthe northeas t an dth e southeas t sites , andth e horizonta l groundwate r speed s fo r thes e tw o site s ar e assume dt o be 1 m/y r an d5 m/yr , respectively . Fo r the southwes t sit e ope ndump , however , th e
6-3 1P.1 8

TABL E 6- 8
. Referenc e Trave l Time s an d Pecle t Number s

Biot a Acces s Locatio n Northeas t Trave l Tim e (years ) Betwee n Sector s - SLF *

- O D

- HW F t o Intrude r Wel l - SLF



## - on

- HW F t o Populatio n Wel l - SLFftHW F

- O D t o Surfac e Strea

m- SLF&HWF

- O D 17 0

3 4 45 5 9 5 1 7 237. 5 250 0 50 0 500 0 100 0 Southeas t

27. 2 6. 8 72. 8 23. 6 3. 4 46. 4 40 0 10 0 80 0 20 0 Southwes t

3. 4 3. 4 9. 1 28 0 28 0 28 0 58 0 58 0 NA* * N A
Pecle t Numbe r Betwee n Sector s - SLF^OD

- HW F t o Intrude r Wel l - SLF&OD

- HW F t o Populatio n Wel l - al l t o Surfac e Strea

m- al l 

### 34 0

91 0 17 0 45 5 1000 0 2000 0 

### 68 0

182 0 

### 34 0 91 0 1000 0 2000 0 

### 34 0

91 0 17 0 45 5 3000 0 

### N A

* SL F OD ' HWF * * N A Sanitar

ylandfil l Ope n dum

p Hazardou s Wast e Facilit y No t Applicabl e

6-3 2P.1 9

aroundwate r speed s and trave l time s ar e assume d t o h e th e same a s thos e fo r the sanitar

ylandfill
. Thi s i s due t o th e thicknes s o f th e unsatu
rate d zone , uniformit yo f topographyand aroundwate r regimes , an d th e semi-ari d natur e o f th e southwes t sit e wit hth e ensuin g lo wstrea m densitie s an

d hig hevaporatio n durina period s o f hia hprecipitation
. Fo r th e on-sit e disposa l facility , th e groun d wate r trave l times , t w i , fro mthe firs t secto r t o the intrude r well , populatio n well , and surfac e stream , and th e trave l time s betwee n two adjacen t disposa l sit e sector s mus t be supplie d b

ythe use r o f the code
. Th e Pecle t number , P-j , i s th e distanc e fro mthe disposa l secto r t o th e biot a acces s locatio n 'divide d b yth e longitudina l dispersivit yo f th e medium
. Longitudina l dispersivitie s fo r th e northeast , southeast , an d southwes t site s ar e assume d t o b e 1 0 cm , 5 cm , and 1 0 cm , respectively
. Pecle t number s fo r th e distance s betwee n the firs t secto r an d th e biot a acces s locations , an d betwee n tw

o adjacen t sectors , ar e determine d i n a manne r simila r t o the trave l times
. Th e Pecle t number s fo r eac hreferenc e sit e an d disposa l facilit yar e give n i n Tabl e 6-8 , alon g wit hth e Pecle t number s correspondin g t o the distance s separating th e centerlin e o f eac h sector . Th e use r o f th e cod e mus t suppl yth e fou r appropriat e Pecle t number s fo r the on-sit e disposa l facility
. Th e discussio n presente d abov e fo r th e variatio n o f trave l time s i s applicabl e t o th e selecte d Pecle t number s a s well
. In thi s manner , th e unsaturate d and saturate d zone s ar e considere d a s a singl e unit
. Th e primar yjustificatio n fo r thi s approac hi s th e generi c natur e o f th e analysis
. Moreover , a s lon g a s the groundwate r trave l time i n th e unsatu
rate d zon e i s adde d t o th e saturate d zon e trave l time , an d th e Pecle t number s fo r the tw

o zone s are

added , the above i s a reasonabl e approxima

tio n t o th e alternativ e o f considering saturate d an d unsaturate d zone s a s tw o unit s wit hthe ensuing complications
. Such. a treatmen t can be foun d i n a previou s wor k b

ythe author s (Ref
. 1)
. I t ma yals o be pointe d ou t tha t using aroundwate r trave l time s (and th e Pecle t number s discusse d above ) a s th e primar yvariable s on whic hth e migratio n analysi s i s based implicitl yallow s fo r a sensitivit yanalysis
. Site s wit hdifferin g environmenta l parameter s ma ylead t o simila r radio

nuclid e concentration s a t th e acces s locations
. Fo r example , simila r result s woul d be obtaine d i f the groundwate r velocit yi s twic e a s hig han d the distanc e t o the acces s locatio n i s twic e a s large
. Similarly , a large r unsaturate d zon e trave l tim e (wate r speed s o f the orde r o f 10" ^ ft/yea r ar e common ) woul d compensat e fo r a shorte r saturate d zon e trave l time
. 6.3. 3 Disposa l Cel l Leachat e Treatmen t an d Overflo w On e o f the difficultie s faced whe n modeling groundwate r impact s associated wit hd e minimi s wast e disposa. 1 int o municipa l landfill s o r hazardou s t wast e facilitie s i s tha t the desion s o f thes e disposa l facilitie s fre

quentl yinclud e installatio n o f disposa l cel l liners
. Thes e liner s are frequentl ydescribe d a s being "impermeable " and ar e intende d t o preven t
6-3 3P.2 0

migratio n o f toxi c material s ou t o f the wast e an d int o the aquife r beneat h th e disposa l facility
. The existanc e o f th e liners , o r alternativel yth e possibilit yo f disposa l o f wast e int o highl yimpermeabl e soils , complicat e groundwate r migratio n calculations , sinc e percolatin g wate r ca n poten
tiall yaccumulat e in rathe r tha n flowthroug

hth e disposa l cells
. Thi s "bathtub " effec t ha s bee n observe d a t low-leve l radioactiv e wast e disposa l facilitie s in the past , an d i f th e wate r i s allowe d t o continu e t o accumulat e s o tha t th e disposa l cel l fill s u p wit hleachate , th e disposa l cel l coul d overflow , in whic hcas e potentia l publi c impact s coul d occur . Alternatively , the disposa l sit e operator s coul d pum p th e accumu latin g leachat e fro mth e disposa l cells , send th e leachat e througha treatmen t process , an d the n releas e th e treate d leachat e t o th e environ

ment . Th e leachat e treatmen t proces s woul d als o involve potentia l publi c impacts , sinc e no treatmen t proces s wil l b e full yeffectiv e i n removin g th e toxi c constituent s fro mthe leachate
. A n orde r o f magnitud e estimat e o f potentia l impact s fro mleachat e treat
men t an

d overflo wi s thu s provided
. Thi s estimat e i s adopte d froma calculationa l procedur e outline d i n Referenc e 12
. Briefly , thre e scenario s ar e considered : 1
. Durin g operatio n o f th e disposa l facility , accumulating leachat e i s continuousl yremoved b ysit e operators , processe d in som e manner , an d release d int o a nearbystream . Th e contaminate d strea mwate r i s consume d an

d used b

ya n individual , an

d impact s t o th e individua l ar e calculate d in unit s o f mrem/yr
. 2
. Accumulatin g leachat e i s allowe d t o completel yfil l u p th e disposa l cell s t o th e poin t tha t th e leachat e overflow s th e disposa l cells
. Th e overflowin g leachat e i s carrie d t o a nearb ystream , an

d impact s fro mconsumptio n an

d us e o f th e contaminate d strea mwate r ar e agai n calculate d in unit s o f mrem/yr
. 3
. Rathe r tha n overflow , th e accumulate d leachat e in th e secon d scenari o abov e i s assume d t o be processe d througha n evaporator . Radionuclide s release d throug hth e evaporato r stack impac t the surrounding popula

tion (in person-mrem/yr)
. Th e firs t scenari o woul d correspon d t o a situatio n in whic ha disposa l facilit yi s designe d fo r leachat e collectio n an d removal
. Thi s woul db e th e cas e a t a hazardou s wast e disposa l facilit y(se e Sectio n C.4. 2 o f Appendi xC) , wher e in accordanc e wit hEP Aregulation s liner s ar e required , an d n o mor e than 1 f t hea d o f leachat e i s allowe d t o buildu p o n the liner . Exampl e treatmen t processe s coul d includ e filtratio n and io n exchang e systems . Th e secon d scenari o correspond s t o a situatio n in whic hin

sufficien t attentio n i s give n t o accumulatin g leachate , whic hcoul d potentiall yoccu r a t som e time afte r th e disposa l facilit yi s closed
. Th e third scenari o correspond s t o a situatio n i n whic hremedia l action s ar e taken a t a closed disposa l facility
. Impact s fro mth e firs t tw o scenario s {H\ an d H2 ) an

d th e third scenari o (P ) ar e thu s give n as : 6-3 4P.2 1



### H i = I I ^ o (Ain/Q ) fi np 

### DCF- 7 (6-30a) " i n 

### H 2 

### = I I f 0 

### '(Ain/Q ) ^2 nPDCF- 7 , (6-30b ) i n
p

### = Z I f 

### o' A 

### i nf 

### r nP0 P PDCF 

### " 3 (6-30c ) i n with : A i n

### = C i n

### f i V

L M 0 

### t c 

### IO* 1 

### " TM ) (6-31 ) where : f 0 

### = decay

correctio nfacto r fo r th e firs t scenari o (se e below) ; f 0 

### ' = decay

correctio nfacto r fo r th e othe r scenario s (se e below) ; A-j n

### = activit y

(Ci ) containe dwithi nleachat e volume (VL ) annuall y

generate do r processed ; Q = flow

rat e o f surfac e strea m (assumedt o be 4.5x10 ° m3/yea r - se e Sectio n6.3.2) ; fi n

### = radionuclid e releas e fractio nfro m operationa l leachat e treatmen t process ; f£ n

### = radionuclid e retentio ni nsoi l duringoverlandflow ; f r n

### = radionuclid e fractio nrelease dint o th e ai r

. du e t o evaporato r operation ; POP = population-weighte datmospheri c dispersio nfacto r (Se e Sectio n4.1.5) : C-j n

### = concentratio n(Ci/m3 ) o f n t n

### radionuclid e i ni* h

### d e minimi s wast e stream ; f- j = fractio no f th e tota l sit e wast e volume tha t i s compose do f th e i t n

### d e minimi s wast e stream ; V L = volume (m3 ) o f leachat e annuall y release do r processed ; M 0 

### = radionuclide-specifi c leac hfractio n(se e Tabl e 6-4) ; t c 

### = fractio no f a yea r tha t th e leachat e i s i ncontac t wit hth e waste ; an

d I A = accessibilit y

index(se e Sectio n2.2.2) . Parameter s requirin gadditiona l explanatio ninclud e f 0 

### , fi n 

### , f2n» frn » VL , andt c 

### . Th e deca y

correctio no r th e .tim e dela y factors , f 0 

### an

df 0 

### ' , accoun t fo r radionuclid e decay . Th e firs t scenari o i s conservativel y assume dt o occu r durin gth e las t yea r o f wast e disposal . Consequently , thi s facto r i s give nb y th e following :
f 0 

### = [l+exp(-x n 

### )+exp(-2x n 

### )+---+exp(-(ILFE-l)x n 

### )]/ILF E (6-32a )
wher e x n

### i s th e radionuclid e deca y constan t (yr - 

### * ) an dILF E i s th e facilit y lif e inyears . Eachter m abov e account s fo r th e decay o f th e d e minimi s wast e dispose di na specifi c year , e.g. , exp(-x n 

### ) i s th e deca y facto r fo r th e d e minimi s wast e dispose ddurin gth e penultimat e yea r o f
6-3 5P.2 2

V Li s difficul t t o estimate , bu tfo rthi s repor t wil l b e assume d t o & e equa l t o th e tota l volum e o fwate rpercolatin g int o th e disposa l cell s pe r year . Thi s volum e i s give n a s th e percolatio n (p ) time s th e effectiv e disposa l sit e surfac e are a (Sf) , wher e S fi s give n as equatio n 6-21

. Thi s als o give s conservativ e results , sinc e i t correspond s t o th e las tyea ro f facilit yoperatio n whe n th e disposa l facilit ywil l b e fille d t o capacit y wit h waste

. Th e percolatio n (p ) i s a functio n o fth e desig n an d operation ! o fth e disposa l facility

. Defaul t value s fo rp fo rmunicipa l an d hazar
dou s wast e disposa l ar e discusse d i n Sectio n 6.3.1

. Fo ron-sit e disposal, , p i s supplie d b yth e cod e user . Th e contac t tim e fraction , t c , als o differ s dependin g upo n th e scenario
Fo rth e firs t scenario , leachat e i s assume d t o b e remove d continuousl y durin g operation , an d s o percolatin g wate ri s assume d t o flo wthroug h th e wast e rathe rtha n saturat e th e wast e continuously

. Thu s t cfo rth e firs t scenari o i s give n a s a functio n o fpercolatio n a s discusse d i n Section

. 6.3. 1 an d liste d i n Tabl e 6-6

. Fo rth e secon d an d thir d scenarios , th e wast e i s assume d t o b e i n continuou s saturate d contac t wit h th e leachate „ an d s o t cfo rthes e las t tw o scenario s i s assume d t o b e unity

. 6. 4 Expose d Wast e Scenario s I n thes e scenarios , th e earthe n cove rove rth e dispose d wast e i s assume d t o b e totall yo rpartiall yremoved , resultin g i n exposur e o fth e wast e a rudi dispersa l b ywin d o rwater

. Tw o possibl e mechanism s ar e considere d fo r remova l o fth e cover : (1 ) th e action s o fa potentia l inadvertan tintrude r (se e Sectio n 6.2) , an d (2 ) erosio n o fth e cove rb ywin d o rsurfac e water Fo reac h remova l mechanism , tw o radiologica l exposur e scenario s ar e considered

. On e involve s suspensio n an d airborn e dispersa l o fcontami
nate d particulate s t o th e are a surroundin g th e disposa l site , leadin g t ® exposure s t o th e surroundin g populatio n resultin g fro m i nha l atioin., , immersio n an d othe rpathways

. Th e secon d scenari o involve s transpor t of radionuclide s vi a surfac e wate rrunof ft o a n off-sit e surfac e wate rbody* leadin g t o exposure s t o individual s usin g th e contaminate d wate rbodj
- Thi s result s i n fou rexpose d wast e scenario s dependin g upo n th e particula r cove rremova l mechanis m an d radionuclid e transpor t agen tconsidered : intruder-air , intruder-water , erosion-air , an d erosion-water

. Th e followin g equation s ar e utilize d t o calculat e huma n exposure s result
- in g fro m thes e scenarios

. Fo rth e wate rtranspor tan d acces s scenarios :
H •I I (Vdfwifs)wa t C i n PDCF-7 (6-33) ) i n and , fo rth e ai rtranspor tan d acces s scenarios :
P = [ [ (Vdfwifs)ai rC i n p DCF- 8 (6-34) ) i n
6-3 7