AN OILSPILL RISK ANALYSIS FOR THE NORTON SOUND, ALASKA,

(PROPOSED SALE 57)

OUTER CONTINENTAL SHELF LEASE AREA

By ',iilliarn B. Samuels and Kenneth J. Lanfear

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U. S. GE9LOGICAL SiJRYEY

OPEN-FILE R E P O R T 31-323

Deci s ionmaki ng under risk and uncer ta in ty --------- 3

Summary o f the proposed action and t he m a j o r a l t e rna t ives 4

E s t i m a t e d quantity o f o i l resources ---------------- 1 I)

Probabi 1 i ty of oil spills occurring ---------------- 11

Oil spi 1 1 t r a jec to ry simulations ------------------- 13

Combi ned anal ysi s o f oi 1 s p i 11 occurrence and oi 1 spill t r a jec to ry sinulations ---------------- 15

11 l u s t r a t i ons

Page I. Yap showing t h e Nor ton Sound

OCS Lease Sa l e 57 study a r e a and the proposed lease t racts . ........................ 5

2 . Map showing the s u b d i v i s i o n s of t he proposed leas? t r a c t s f o r Nor ton Sound 9CS Lease S a l e 57. ...................... 5

3 . ,Yap showing t h e 1,aunch p o i n t s which r e p r e s e n t p l a t f o m 1 o c a t i o n s , p ipe1 ines (dashed 1 i nes) , and tanker routes ( s o l i d 1 inzs) . Polygons represent proposed qease t rac ts . -------------- 7

4 . i4ap showing the division of t he Norton Sound open sea boundary and coast1 i ne i n t o 34 szgments o f a p p r o x i m a ~ s l y equal l z n g t h . ---- 9

5 . Estimated frzquency d i s t r i a u t i o n f o r oil s p i l l s greater t h a n 1,000 and 10,000 barrels o c c u r r i n g d u r i ng t i l e e x p c t ed p r o d u c t i on 1 i i? of the g raposed lease t r ac t s f o r Norton Sound oCS Lease Sa l z 57 . 15

5. Results of a significance tes t for any two q r g b a b i l i t i e s (45 t r i a l s , 90 percent c o n f i d e n c e l e v e l ) . ............................. 13

Page

1. O i l s p i l 1 p r o b a b i l i t y e s t i m a t e s f o r s p i l l s greater t h a n 1,000 and 10,000 b a r r e l s r e s c l t i n g f r o m ~ C S Lease Sa l e 57. 1 4

2 . Monte C a r l o e r r o r as a f u n c t i o n of t h e number o f t r i a l s and the estimated p r o b a S i l i t y . ------ 17

3 . P r o b a b i l i t i e s ( e x p r e s s e d as p e r c e n t c h a n c e ) t h a t a n o i l s p i l l s t a r t i n g a t a p a r t i c u l a r l o c a t i o n w i l l c o n t a c t a c e r t a i n t a r g e t w i t h i n 3 days . -- 19

4. P r o b a b i l i t i e s ( e x p r e s s e d a s p e r c e n t c ? a n c e ) t h a t an o i l s p i l l s t a r t i n g a t a p a r t i c u l a r l o c a t i o n w i l l c o n t a c t a c e r t a i n t a r g e t w i t n i n 10 days . 2 0

5. P r o b a b i l i t i e s ( e x p r e s s e d as p e r c e n t c h a n c e ) t h a t an o i l s p i l l s t a r z i n g a t a p a r t i c u l a r l o c a t i o n wi l 1 c o n t a c t a c e r t a i n t a r g e t w i t h i n 30 days. 21

6 . P robab i 1 i t i e s ( e x p r e s s s d a s 9 e r c e n t c h a n c e ) t h a t a n o i l s p i l 1 s t a r t i n g a t a p a r t i c u l a r l o c a t i o n w i l l c o n t a c t a c e r t a i n l and o r sea segment w i t h i n 3 days, ............................... 2 2

7 . P r o b a b i l i t i e s ( e x p r e s s e d as g e r c e n t chance) t h a t a n o i l s p i l l s t a r t i n g a t a p a r t i c u l a r l o c a t i o n w i l l c o n t a c t a c e r t a i n l and or sea segment w i t h i n 10 d a y s . .............................. 2 3

8. P r o b a b i l i t i e s ( e x p r e s s e d a s percent chance) t h a t a n o i l s p i l 1 s t a r t i n g a t a p a r t i c u l a r l o c a t i o n w i i l contac t a c e r t a i n l a n d or sea s e g n e n t w i t h i n 30 days. .............................. ? 4

9. P r o b a b i l i t i e s ( e x p r e s s e d as p e r c e n t c h a n c e ) o f one o r more s p i l l s , the most l i k e l y number o f s p i 11 s (mode) and the e x p e c t e d number of s p i l l s (mean) o c c u r r i n g and c o n t a c t i n g t a r g e t s o v e r tne p r o d u c t i o n l i f e o f t h e p r ~ p o s e d l e a s e t r a c t s u s i n g o n s h o r e t r a n s p o r t a t i o n s c e n a r i o . - 26

i i i

Tables (continued) - Page

10. Probabi l i t ies (expressed as percent chance) of one or more spi 1 Is, the most [ ike ly number o f spil Is (mode) and the expected number of s p i l l s (mean) occurring and contacting t a rge t s over the product ion l i f e of the proposed lease t r a c t s u s i n g offshore transportat ion scenario. 2 /

11. Probabi I1 t i e s (expressed as percent chance) of one or aore spi l I s , t h e most l ikely number of s p i l l s (mode), and the expected number of s p i 1 Is (mean) occurring and contact ing t a rge t s over the production l i f e of the north delet ion a l t e rna t ive using onshore t r an spo r t a t~on scenarl 0. ...................... 23

12. Probabi l i t ies (expressed as percent chance) of one or m r e spi l Is, the most l i k e l y number o f spil Is (mode), and the expected number of s p i l Is (mean) occurring and contacting t a rge t s over the production l i f 2 o f the n o r t h delet ion a l t e rna t ive using offshore transportat ion scenario. ---------------------- 29

13. Probabi l i t ies (expressed as percent chance) of one or ;I;;;'? spil Is , the most likely number o f s p i l Is (node), and the expected number o f spi l Is (mean) occurring and contacting t a rge t s over the product~on l i f e o f the south delet ion a l ternat ive using onshore transportat ion scenario. -------------- 30

14. ProbaSi l i t ies (expressed as percent chance) o f one or sore s p i l l s , t h e most l ikely number of spi 1 l s (mode), and the expected number of s p i l l s (mean) occurring and contacting t a rge t s over the production l i f e of the south delet ion a l t2rnat ive using offshore t r an spo r t a t~on scenario. ------------- 3 1

15. Probabi l i t ies (zxpressed as percent chance) of one or more s p i l l s , the most l i k e l y number of spi 1 I s (mode), and the expected number of s p i l l s (mean) occurring and contacting t a rge t s ove r the production l i f e of the eas t delet ion a l t e r n ~ t i v e using onshore transportat ion scenario. -------------- 3 2

Tab1 es (continued) Page

15. Probabi l i t ies (expressed as percent chance) of one o r more s p i l l s , the most l ike ly number of s p i l l s (mode), and the expected number of spi 1 1 s (mean) occurring and contacting t a rge t s over the production l i f e of the eas t delet ion a l t e rna t ive using offshore t ranspor ta t i o n scenariorio. ------------- 33

1 7 . Probabi l i t ies (expressed as percent chance) of one o r more s p i l l s , the most l ike ly number of spi 1 1 s (node), and the expected nunber of s p i l l s (mean) occurring and contacting l a n d and sea segments over the production l i f ? of the proposed lease t r a c t s using onshore transportat ion scenario. -------------- 3 4

18. Probabi 1 i t i e s (2xpressed as percent chance) of one or ?ore spil l s , the most 1 ikely number of s p i l l s (mode), and the expected number o f s p i l l s (mean) occurring and contacting land and sea segments over the production l i f e of the proposed lease t r a c t s using o f f s h o r e t ransportat ion scenario. ------------- 3 5

19. Probabi 1 i t i es (expressed as percent chance) of one or more s p i l l s , the most l ikely number of s p i l l s (mode), and the expected number of spi 1 1 s (mean) occurring and contacting 1 and and sea segments over the production l i f e of the n o r t h delet ion a1 ternat ive using onshore t ranspor ta t ion scenario. -------------- 3 5

20. Probabi l i t ies (expressed as percent chance) of one o r more s p i l l s , t h e most l ike ly numer of sp i l l s (mode), and the expected number of sp i l l s (mean) occurring and contacting land and sea segments over the production l i f e o f t he north delet ion a1 te rnat ive using offshore transportat ion scenario. ------------- 3 7

Tab1 es (continued) Page

21. Probabi 1 i t i e s (expressed as percent chance) o f one or more s p i l l s , the most l ike ly number of s p i l l s (mode), and the expected number of sp i l l s (mean) occurri ng and contacting 1 and and sea segments over the production l i f e of the south delet ion a1 ternat ive using onshore transportat ion scenario. -------------- 38

22. Probabi l i t ies (expressed as percent chance) of one o r more s p i l l s , the most l ike ly nunber of spi 1 1 s (mode), and t h e expected number of s p i l l s (mean) occurring and contacting land and sea segments over the production l i f e of t h e south delet ion a l ternat ive using off shore t ranspor ta t ion scenario. ------------- 39

23. Probabi 1 i t i es (expressed as percent chance) of one or more spi 1 1 s , the most l i kely number of spi 1 1 s (mode), and the expected number of s p i l l s (mean) occurring and contacting land and sea segments over the production l i f a of the eas t delet ion a1 te rnat ive using onshore transportat ion scenario. -------------- 40

24. Probabi l i t ies (expressed as percent chance) o f one o r more spil l s , the most l ike ly number 3f spi 1 1 s (mode), and the expected number of sp i l l s (mean) occurring and contacting l a n d and sea segments over the production 1 i f e of the eas t delet ion a l ternat ive using offshore transportat ion scenario. ------------- 4 1

AN OILSPILL RISK ANALYSIS FOR THE N O R T O N SOUND, ALASKA,

(PROPOSED SALE 57)

OUTER CONTINENTAL SHELF L E A S E A R E A

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By Will i am B . Samuel s and Kenneth J . Lanfear

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Abstract - An o i l s p i l l r i s k analysis was conducted to determine the re la t ive

environmental hazards of developing oil i n d i f fe ren t regions of the Norton Sound, Alaska, (Proposed Sale 5 7 ) Outer Conti nental She1 f ( O C S ) lease area. The probabi 1 i t y of s p i l l occurrences, 1 i kely rnovenent of oi l s l i ck s , and locations of resources vulnerable t o sp i l l ed oil were analyzed. T h e times between sp i l l occurrence and contact w i t h various resources were a1 so estimated. The combined resu l t s yi el ded estimates 3 f the overall r i sks associ ated with development of the proposed lease area. Assuming t ha t o i l ex i s t s i n the lease area ( a 14-percent chance) and depend; ng upon the routes chosen t o transport o i l from 3 C S platforms t a the shore, the leasing of the t r a c t s proposed f o r OCS Sale 57 will r e su l t i z Jn expected 2.8 o i l s p i l l s (o f 1,000 barre ls or l a rge r ) . The estimated probability t ha t land will be contacted by one or more o i l s p i l l s ( o f 1,000 bar re l s or l a rge r ) t h a t have been a t sea l e s s than 30 days i s 0.51 t o C.53, depending on the proposed transportat ion method chosen.

I n t roduc t i on - The Federal Government has proposed t o o f f e r Outer Con t inen ta l

She l f ( O C S ) lands o f f t h e Nor ton Sound, Alaska, coas t f o r o i l and gas leas ing . The c o n d i t i o n a l mean es t imate of o i l resources f o r t h e proposed 429 t r a c t s i s 480 m i l l i o n b a r r e l s of crude o i l . The p r o b a b i l i t y t h a t o i l occurs i n commercial q u a n t i t i e s i n t h e s a l e area i s 14 percent . The chance t h a t o i 1 w i 1 1 no t be found i n economical l y recoverab le q u a n t i t i e s i s 86 percent . T h i s r e p o r t examines what cou ld happen i f o i l i s found. Cont ingent upon ac tua l d i scovery of o i l , p roduc t i on i s expected t o span a p e r i o d o f 25 years.

O i l s p i l l s a re a major problem assoc ia ted w i t h o f f s h o r e o i l p roduc t ion . An impor tan t f a c t t h a t stands ou t when one a t tempts t o eva lua te t h e s i g n i f i c a n c e o f acc iden ta l o i l s p i l l s i s t h a t t h e problem i s fundamental l y p robab i l i s t i c . Unce r t a i n t y e x i s t s about t he amount o f o i l t h a t w i l l be produced from t h e leases and t h e number and s i z e o f s p i l l s t h a t m igh t occur du r i ng t h e l i f e of p roduc t ion , as w e l l as t h e wind and c u r r e n t c o n d i t i o n s t h a t would e x i s t a t t he t i m e o f a s p i l l occurrence and give d i r e c t i o n t o t h e o i l s l i c k . Al though some o f t h e u n c e r t a i n t y r e f l e c t s incomplete and imper fec t data, cons iderab le u n c e r t a i n t y i s s imp ly i nhe ren t i n t h e problem of d e s c r i b i ng f u t u r e events over which complete c o n t r o l cannot be exerc ised. Since i t can no t be p r e d i c t e d w i t h c e r t a i n t y t h a t a p robab i l i s t i c event such as an o i 1 s p i l l w i 11 occur, o n l y t h e l i k e 1 ihood o f occurrence can he q u a n t i f i e d . The range o f poss ib l e e f f e c t s t h a t lnay accompany a d e c i s i o n ~n n i l and gas p roduc t i on must 5e considered. I n a t tempt ing t o m a i n t a i n perspec t i ve on t he p r ~ b l e m , each p o t e n t i a l e f fec t must be assoc ia ted w i t h a q u a n t i t a t i v e es t imate of i t s p r o b a b i l i t y o f occurrence.

Th i s r e p o r t sumnarizes r e s u l t s o f an o i l s p i l l r i s k a n a l y s i s conducted f o r t h e proposed Nor ton Sound OCS Lease Sale 57. The s tudy had t h e o b j e c t i v e o f de te rmin ing re1 a t i v e r i s k s assoc ia ted w i t h o i l and gas p roduc t i on i n d i f f e r e n t reg ions of t h e proposed lease area. The s tudy was undertaken f o r cons ide ra t i on i n t h e d r a f t environmental i npac t statement ( E I S ) , which i s prepared f o r t h e area by t h e Bureau o f Land Management (BLM), and t 3 a i d i n t h e f i n a l s e l e c t i o n o f t r a c t s t o be o f f e r e d f o r sa le . A d e s c r i p t i o n o f t h e o i l s p i l l t r a j e c t o r y a n a l y s i s model used i n t h i s a n a l y s i s can be found i n p rev ious papers (Lanfear and others , 1979; Smith and o thers , 1980; Lanfear and Samuels, 1981). The a n a l y s i s was conducted i n t h r e e p a r t s corresponding t o d i f f e r e n t aspects o f t h e o v e r a l l problen. The f i r s t p a r t d e a l t w i t h t h e p r o b a P i l i t y o f o i 1 s p i l l occurrence, and t h e second w i t h t h e t r a j e c t o r i e s of o i l s p i l l s f rom p o t e n t i a l launch p o i n t s t o va r ious t a rge t s . Resu l t s o f t h e f i r s t two p a r t s o f t h e a n a l y s i s were then combined t o g i ve est imates o f t he overa l 1 o i l s p i l l r i s k assoc ia ted w i t h o i 1 and gas p roduc t i on i n t h e lease area.

Decisionmaking Under R isk and U n c e r t a i n t y

O i l s p i 1 1 impacts r e s u l t p r i m a r i l y f rom two events t h a t a re probabi 1 i s t i c i n na tu re : o i 1 s p i l l occurrence caused by acc idents , and o i l s p i l l movement d i r e c t e d by random winds and cur ren ts . Al though a p r o b a b i l i s t i c event ( s ~ h as an o i l s p i l l ) cannot be p red i c t ed w i t h c e r t a i n t y , t h e l i k e 1 ihood o f occurrence can be q u a n t i f i e d . The l i k e l i h o o d t h a t o i l s p i l l s w i l l r e s u l t f rom an OCS l e a s i n g d e c i s i o n can be est imated, b u t whether they w i l l a c t u a l l y occur can o n l y be known a f t e r t h e area i s exp lored and t h e o i l , i f any, i s produced. Th i s s i t u a t i o n i s i n c o n t r a s t t o a d e t e r m i n i s t i c s i t u a t i o n where a p a r t i c u l a r a c t i o n can be depended upon t o produce a s p e c i f i c r e s u l t .

I n making dec is ions under r i s k and u n c e r t a i n t y , i n v e s t i g a t o r s must understand t h a t a cho ice can have a range o f p o s s i b l e outcomes. Genera l ly , a d e s i r e t o maximize t h e l i k e l i h o o d o f t h e most f avo rab le outcomes must be tempered by t he need t o min imize t he p robab i l i t y o f h i g h l y unfavorab le outcomes. The U .S. Geolog ica l Survey (USGS) O i 1 sp i 11 T r a j e c t o r y Ana l ys i s (OSTA) Yodel was designed t o r e f l e c t t h e range o f poss i b l e outcomes o f l e a s i n g dec is ions by e s t i m a t i n g t h e p r o b a b i l i t y o f occurrence f o r each d i s c re te outcome; s p e c i f i c a l l y , i t est imates t h e 1 i k e l i hood t h a t a p a r t i c u l a r t a r g e t w i l l be contacted by 0, 1, 2, ..., N o i l s p i l 1s du r i ng t h e p roduc t i on 1 i f e o f an O C S lease area.

The p r o b a b i l i t y t k z t , i f an o i l s p i l l occurs a t a g i ven launch po in t , i t w i l l con tac t a p a r t i c u l a r t a r g e t i s termed a c o n d i t i o n a l p r o b a b i l i t y . Such c o n d i t i o n a l p robab i l i t i e s can be very use fu l i n i d e n t i f y i n g those launch p o i n t s a t which an o i l s p i l l , i f i t occurs, w i l l pose t n e h i ghes t r i s k s t o va r i ous t a rge t s . Tables o f c o n d i t i o n a l probabi 1 i t i e s can he1 p t h e ana l ys t t o s e l e c t a1 t e r n a t i ves t h a t w i l 1 reduce o v e r a l l r i s k . However, condi t i o n a l p r o b a b i l i t i e s do no t i n c l u d e t h e p r o b a b i l i t y o f o i l s p i l l occurrence. It i s assumed t h a t a t r a c t t h a t con ta ins l i t t l e o r no o i l i s a smal 1 r i s k because, no ma t t e r how h igh t h e c o n d i t i o n a l p r o b a b i l i t y o f c o n t a c t i n g a t a r g e t nay be, t h e small amount o f o i l makes i t u n l i k e l y t h a t an o i l s p i l l w i l l occur. A lso, c o n d i t i o n a l probabi l i t i e s f o r s p i l l s o r i g i n a t i n g a t t h e p roduc t i on p l a t f o rms do no t necessa r i l y r e f l e c t t h e r i s k s o f s p i l l s du r i ng t r a n s p o r t a t i o n . For these reasons, ana l ys t s a re caut ioned aga ins t bas ing judgments s o l e l y upon c o n d i t i o n a l ~ r o b a b i l i t i e s .

Summary of the Proposed Action and the Major Alternatives - The proposed action i s t o lease 429 t r ac t s on the Outer

Continental Shelf off the Norton Sound coast. The study area for th i s analysis includes a1 1 of these t rac ts and extends from lat i tude 62 degrees N t o 56 degrees 5 minutes N , and from longitude 159 degrees 24 minutes i4 t o 169 degrees 7 minutes W .

The study area and the proposed t rac ts are shown on a blercator projection in f igure 1. The subdivisions of the proposed t r ac t s are shown in figure 2 . The launch points, which represent p la t fo rm locations, pipe1 ine routes, and tanker routes, are shown in figure 3. Two oil transportation scenarios were analyzed for the proposed action and each of three t r ac t deletion alternatives, In t h e f i r s t scenario (referred t o as "onshore"), a1 1 the oil from the lease area wculd be piped t o a terminal onshore (P8) near Nome, Alaska. From there, the oil w o u l d be transported south by tankers o u t of the study area. I n the second scenario, (referred to as "offshore") a l l the oil would be piped t o a n offshore terminal ( P 1 1 ) near the center of the lease area. Fran there the oil would be tankered south o u t of the study area. The three t rac t deletion alt2rnatives a r e as follows:

1. northern t r ac t s deleted ( t r ac t groups A and B ) 2. southern t r ac t s d e l e t ~ d ( t r ac t groups E , F , and G ) 3 . eastern t r ac t s deleted ( t r ac t groups B, D, and G )

For the offshore transportation scenario of the east deletion alternative, the oil from the remaining t rac ts i s piped t o a terminal near the southeast edge of the lease area ( P 2 ) and tankered south from there.

Envi ronmental Resources

The locations o f 19 categories o f biological resources (or targets, as they are designated in th i s paper) were digitized i n the same coordinate system, or base nap, as that used i n trajectory simulations. Targets were selected by BLM analysts. Maps showing the digitized targets are shown i n appendix A , figures A - 1 t o A-19. The m o n t h l y sensit ivity of these targets was also recorded so tha t , for example, a target such as migrating birds could be contacted by simulated o i l sp i l l s only when the birds would be in the area. Mid-boundary and seabird foraging areas 1 through 5 were given two sets of seasonal vulnerabilities (surrmer and winter). I n t h i s analysis, the winter season includes the months December t o Nay, and the summer season includes the months June t o November. The targets are l is ted below:

Average shorefast ice zone 1 (winter) AS:arage shorefast ice zone 2 (wi nter) Average shorefast ice zone 3 (winter) Average shorefast ice zone 4 (winter)

Average s h o r e f a s t i c e zone 5 ( w i n t e r ) Average s h o r e f a s t i c e zone 6 ( w i n t e r ) Mid-boundary a r e a 1 (summer) blid-boundary a r e a 2 ( sumner ) :did-boundary a r e a 3 (summer) Nid-boundary a r e a 4 ( s u m e r ) Yid-boundary a r e a 5 ( sumner ) Mid-boundary a r e a 1 ( w i n t e r ) Mid-boundary a r e a 2 ( w i n t e r ) ? l id-boundary a r e a 3 ( w i n t e r ) Yid-boundary area 4 ( w i n t e r ) Mid-boundary a r e a 5 ( w i n t e r ) S e a b i r d f o r a g i n g area 1 ( sumner ) S e a b i r d f o r a g i n g area 2 ( s u m n e r ) S e a b i r d f o r a g i n g a r e a 3 ( s u m e r ) S e a b i r d f o r a g i n g a r g a 4 (summer) S e a b i r d f o r a g i n g a r e a 5 ( sumner ) S e a b i r d f o r a g i n g area 1 ( w i n t e r ) S e a b i r d f o r a g i n g a r e a 2 ( w i n t e r ) S e a b i r d f o r a g i n g a r e a 3 ( w i n t e r ) Seab i r d f o r a g i n g a r e a 4 ( w i n t e r ) S e a b i r d for-aging a r e a 5 ( w i n t e r ) K i n g c r a b f i s h e r y a r e a ( s u m e r ) Yukon D e l t a e n t r a i n m e n t a r e a ( s u r m e r ) Gray whal e f e e d i ng a r e a and h y p o t h e t i c a l Bowhead

w h a l e m i g r a t i o n c o r r i d o r (summer and w i nter )

Because the t r a j e c t o r y node l s i m u l a t e s a n o i l s p i l l a s a p o i n t , most t a r g e t s have been g i v e n a n a r e a l e x t e n t s l i g h t l y g r e a t e r t h a n they a c t u a l l y occupy. F o r example, some s h o r e l i n e t a r g e t s e x t e n d a s n o r t dis tance o f f s h o r e ; t h i s al lows the model t o s i m u l a t e a s p i l l t h a t a p p r o a c h e s 1 a n d , makes p a r t i a1 c o n t a c t , w i t h d r a w s , and c o n t i n u e s on i t s way.

To p r o v i d e a more d e t a i l e d a n a l y s i s f o r l and o r l and -based targets, the model i n c l u d e s a f e a t u r e t h a t a1 lows s u b d i v i d i n g t h e c o a s t l i ne i n t o land segments. F i g u r e 4 shows the c o a s t l i n e d i v i d e d i n t o 24 segmen t s of approx imate ly equa l l e n g t h . The open sea hounda r i es were a1 s o d i v i d e d i n t o 10 segments of approxi rna te l y q u a 1 l e n g t h .

Estimated guantity of Oil Resources

Considerable uncertainty exists in estimating the volume of oil t h a t will be discovered and produced as a result of an OCS lease sale. A question exis ts as to whether oil sp i l l risk calculations should be based upon a single estimate of volume, or should consider volume as a random variable and include some probability di stribution for volume in computing o i l sp i l l occurrence probabilities. The choice may depend upon how the results are t o be incorporated i n t o the benefitlrisk analysis.

Benefits and risks (as well as many environmental impacts), are functions o f t h e volume of o i l , and are not independent of each other. Greater risks are associated with greater volu~nes o f oil and greater economic benefits. If benefits are evaluated by assuming production o f a specific amount of o i l , then the corresponding risks should be stated i n a conditional form such as , " the risks are ..., given that the volume i s ..." I f benefits are evaluated for a number of discrete volumes, then risks should likewise be calculated for t h e same volumes. Any statements about the 1 ikel i hood of the presence of a particular volume o f o i l apply equally well t o the likelihood of the corresponding benefits and risks.

The estimated o i l resources used for o i l sp i l l risk calculations in th i s report correspond t o those used by BLM i n preparing the draf t € IS f o r the l ease sale. These estimates are based on those derived by the Conservation Division, USGS fo r the draf t € I S in August 1980. A 14 percent chance exis ts that oil i s present in economical l y recoverable quantities in the sale area. If o i l i s present, then a n estimated conditional mean value o f 480 mil lion barrels, distributed among the various subareas, may occur. For the deletion a1 ternatives, the prohabili t y of commercial oil being present was assumed t o remain the same (14 percent), b u t the quantities remaining were 250, 480, and 98 mil l i o n barrels for t h e north, south, and east deletion alternatives, respectively. These conditional mean estimates are also based on those derived by the Conservation Division, USGS for the draft EIS in August 1980. Note that i f the south deletion alternative i s chosen, the remaining t r ac t s have a resource estimate equal t o the amount predicted for the ent i re sale area. These southern t r ac t s are be1 ieved t o be gas prone instead o f o i l bearing. We cannot overemphasize t h a t these estimates are based on the assumption that oil i s present; i f i t i s not present ( a n 86 percent probahil i t y ) , then, obviously, no o i l sp i l l risks exist . The remainder o f t h i s analysis i s designed t o answer the question, "'dhat are the risks i f o i l i s found?"

Probabi 1 i ty of Oi l spi 11 s Occurri ng

The probabil i t y o f oi l sp i l l occurrence (given that oil i s present) i s based on the fundamental assumption that real i s t i c estimates of future sp i l l frequencies can be based on past OCS experience. This analysis i s Pased on the assumption that sp i l l s occur independently of each other as a Poisson process and that the sp i l l ra te i s dependent upon the volune o f oil produced or transported. This l a s t assumption - that sp i l l rate i s a function of the volume of oil handled - m i g h t be modified on the basis of s ize , extent, frequency, or duration of the handling. In the case o f tanker transport, for example, the number of port ca l l s and the number of tanker-years have been contemplated (Stewart, 1976, and Stewart and Kennedy, 1973). This analysis i s based o n volume o f oil handled, s ince a1 1 other estimates must ultimately be derived fran th i s quantity.

This analysis includes a1 1 types of sp i l l s resulting from OCS leasing. I t considers not only we1 1 blowouts, b u t also other accidents on platforms, transportation of the oil t o shore, and, in some cases, further transportation fron a n intermediate terminus t o refineries. Incl ud i ng a1 1 of these risks a1 lows the risks of the proposed OCS leasing t o be cmpared t o those o f other alternatives, such as importing o i l . Previous 3SGS d a t a on OCS accidents, (Dannenberger, 1975; 1980) are included i n the data base, b u t cmprise only a part of the data,

I n past model runs, on ly spil 1s larger than 1,000 barrels ( b b l ) were considered. This report examines, when the d a t a pemi t , sp i l l s i n two s i z e ranges: 10,000 barrels or greater, and 1,000 barrels or greater (which i s included i n the f i r s t category). To place these sizes i n a rough perspective, s p i l l s in the largest category are usual l y associated with catastrophies such as 1 arge blowouts or shipwrecks. Accidents in the second category typical ly include those and other serious events, such as structural fa i lures and tanker col l i sions. The choice of size range t o be uszd depends upon the analysis being performed. I f , for example, a particular impact could occur only from a massive o i l s l ick , then o n l y large s p i l l s would be examined.

Accident rates for platforms on the U.S. OCS were derived fr3m USGS accident f i l e s (USGS, 1973a and b ) , and from 3SI;S production records (USGS, 1980). For spi 11s of 1,000 barrels or larger, the period from 1964 t o 1979 was used. Between 1964 and 1979, four s p i l l s of 10,000 barrels or larger occurred, and nine sp i l l s (including the four) of 1,000 barrels o r larger occurred. During t h i s period, 3.S. OCS oil production was 4,386 million barrels.

USGS accident f i l e s a re a1 so a major source of da t a f o r pipeline accidents. As with p la t foms , the period from 1964 t o 1979 was used f o r s p i l l s of 1,000 barre ls o r larger . USGS f i l e s (1979a and b ) include two s p i l l s of over 13,000 barrels and seven s p i l l s (including the two) o f over 1,000 barre ls . Devanney and Stewart (1976) report s ix additional pipe1 ine spil l s , b u t a1 1 except one (1,020 barrel s ) occurred i n coastal channel s. Adding t h i s one sp i l l to the USSS data gives a to ta l of eight s p i l l s o f 1,000 barre ls o r larger . Since nearly a1 1 U.S. OCS production has been transparted t a shore by pipelines, the same production s t a t i s t i c s used fo r p l a t f o n s c a n be applied t o the pipeline accident data.

Accident data and oil t ransportat ion data f o r tankers i s not maintained by the USGS, so tanker accident ra tes must be derived f r m published l i t e r a tu r e . The tanker accident r a t e f o r s p i l l s o f 1,000 barre ls or l a rger , used in recent OSTA models, i s from Stewart (1976): 178 s p i l l s in 45,941 million barre ls of oil transported. No detai led l i s t i n g o f these s p i l l s ex i s t s in the pub1 i shed 1 i t e ra ture . However, Devanney and Stewart (1974) exami ned tanker s p i l l s on major t rade routes, and reported 99 s p i l l s greater t h a n 42,000 gallons (1,000 ba r r e l s ) , 87 s p i l l s greater t h a n 100,000 gallons, and 32 s p i l l s greater than 1,000,000 gallons. Interpolat ion o f t h i s data gives about 53 spi l 1s greater than 10,000 bar re l s , or about 54 percent of the 1,000-barrel spi 1 1 ra te . This estimate can be pa r t i a l l y confirmed by l i s t i n g s of s p i l l s in Oil s p i l l I n t e l ligence Report (1979 and 1980) where, o u t o f 22 s p i l l s of crude o i l from bulk ca r r i e r s reported for 1975 and 1979, and known or estimated t o be l a rger t h a n 1 ,000 barre ls , 15, or 68 percent, were larger than 10,000 barre ls . Therefore, a r a t i o o f 60 percent of the 1,000-barrel r a t e appears reasonab 1 e , g i v i ng an estimated s p i l l r a t e f o r 10,000 barrel and larger s p i l l s of 107 per 45,941 million barrels .

In summary, the sp i l l r a t e s used in t h i s report are :

Sp i l l s per S i l l i on barre ls 1,000+ b b l 10,000+ b b l

P I atforms 2.05 0.31

P i pel i nes 1.82 0.46

Tankers 3.87 2.32

Are these rates applicable t o Alaska, s ince most of the exist ing data a re from more temperate c l irnates? About 400 mil l i o n barrel s of petroleum have been produced from platforms i n Cook I n l e t , piped to shore, and transported south by tankers; no s p i l l s of 1,000 ~ a r r e l s or greater have occurred. Applying the s p i l l r a tes used i n t h i s a n a l y s i s , we find a 10-percent chance of no s p i l l s i n producing and

transporting 400 m i l lion barrels in th i s nanner. Thus, the data base fo r Alaska (400million barrels) i s st511 too small t o say, with a high degree of confidence, that the Alaskan sp i l l rat2

. differs from the rate for the rest of the U.S. OCS. This conclusion, however, will need t o be reviewed i f the commendable safety record of Alaskan operations continues for a longer period.

Spill frequency estimates were calculated for production and transportation of o i l from Sale 57. Table 1 shows the expected number o f sp i l l s and the most l ikely number of sp i l l s t h a t will occur during the expected production l i f ? of the lease area. Figure 5 shows the probabil i ty t h a t 9, 1, 2 , . . . , N spi 11s w i 1 1 occur.

Oilspill Trajectory Sirnulitions - Oil sp i l l t ra jector ies were sirnulatzd by the Rand Corporation,

Santa Monica, Cal i f., usi ng the i r three-dinensional model for estuaries and coastal seas (Liu a n d Nelson, 1 9 7 7 ) . The application of t h i s model was devei oped as part of the 3LM environmental s tudies program in the aering Sea. Twenty launch points were selected representing p l a t f o r m 1 ocations, pi pel i nes, and tanker routes in the s t u d y area. I n t h i s analysis, the location of the center o f mass of each hypothetical o i l sp i l l was reported every 12 hours. J i l sp i l l t ra jector ies werz simulated under three se ts of environmental conditions. The f i r s t s e t , which included the months December t o Yay, was tenned the ice-cover condition. During th i s period, Norton Sound i s covered by ice floes. For each launch point, 10 o i 1 s p i l l s were simulated under di f f e re f~ t weather scenarios. The second set was an ice-free condition which included the months June t o August. Because of t h e variabil i t y of t h e weather during t h i s period, 26 hypothetical o i l s p i l l s were launched from each s i t e . The third se t was also an ice-free condition including the months S?pter;~ber t o November. During th is period, ten hypothetical oilspi1 1s were launched from each s i t e . The t ra jec tor ies calculated by Rand were transmitted t o the U.S. Geological Survey, Reston, Va., on computer-compatible tapes. The x,y coordinates o f the trajectcrries in the ftand grid system were FoRverted t o the USGS grid system by a l inear t ransfonat ion. As the simulated o i l sp i l l was moved, any contacts with targets were recorded. Spill novement continued until the spi l l h i t land, moved off the map, or aged more than 30 days.

The t ra jec tor ies simulated by the model represent only hypothetical pathways of oil sl icks and d o not involve any direct consideration of cleanup, dispersion, or weathering processzs which could determine the quantity or quai i t y of oil that .might eventually come i n contact with targets. A n implicit analysis o f weathering a n d decay can be considered by noting the age of

Table 1. -- Oilsp i l l probabil i ty estimates f o r spil 1s greater than 1,000 and 10,000 barre ls result ing f rom OCS Lease Sale 57.

Prouosed a c t i o n (onshore and o f f shore scenarios)

North delet ion (onshore and offshore scenarios)

S o u t n delet ion (onshore and o f f s h o r e scenarios )

East delet ion (onsho re and offshore scenaricz)

Expected number Yos t l i k e l y o f s p i l l s (mean). number of

s p i l l s (mode). >1,000 >10,000 >1,000 >10,000

Probabil i t y of one or more spil Is >1,000 >10,000

" l o 7 n '7 0 0 L 5

L Q OJ %-c

simulated o i l sp i l l s when they contact targets. For th i s analysis, three time periods were selected: 3 days, t o represent diminished toxicity of the s p i l l ; 10 days, t o allow for deployment of cleanup equipment; a n d 30 days, t o represent the diff icul ty of tracking or locating sp i l l s a f te r t h i s time.

When calculating probabilities from Yonte Carlo t r i a l s i t i s desirable t o estimate the error associated with t h i s technique. The calculation of the standard deviation s, for a particular - prooability p i s calculated as follows: - where N = number o f t r i a l s . The shape of th i s distribution approxizates the normal curve, thus, table 2 shows, for the 90-percent confidence level of t h i s distribution, values o f s as a function of p and N . When comparing two probabilities; the investigator ' s h o u l d - a1 so t e s t whether the two values are significantly different from each other. Figure 5 shows the results o f t h i s significance t e s t , based on the formula above ( N = 46, 90-percent confidence level ) . Points lyi ng within the shaBed portion of the g r a p h are n o t significantly different from each other.

Each entry i n tables 3 , 4 , and 5 represents the probability (expressed as percent chance) tha t , i f a spi l l s t a r t s from a certain launch point, i t wil 1 contact a particular target within 3 , 10, or 30 days, respectively. Tables 5 , 7 , and 8 present simil a r probabilities for l a n d and sea segments. These conditional probabilities a l l o w for the possibility t h a t the targets may no t be vulnerable t o o i l sp i l l s for the en t i re year: a target t h a t i s vulnerable for only 1 month, for example, could have a conditional probability no higher than about 1/12.

Combined Analysis of Oilspill Occurrence and g i T Z i T 7 I r a j e c f ~ i o n s -

Data i n figure 5 indicate the probabilities of different numbers of o i l sp i l l s occurring. Tables 3 t o 8 indicate the probabilities that targets or land or sea segments will be contacted, given that an o i l sp i l l occurs. Combining these two se t s of probabilities yields estimates of the chances that o i l sp i l l s will occur and contact targets or land segments.

A c r i t i c a l d i fference e x i s ts between the condi t i onal probabilities calculated i n the previous section and t h e overall probabilities calculated i n t h i s section. Condi t i o n a l probabilities depend o n l y on t h e winds and currents i n the study area -- elements over which the decisionmaker has no control. Overall p r o ~ a u i l i t i e s , on the other hand, will depend not only 3 n

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the physical conditions, b u t also on the course of action chosen by the decisionmaker, that i s , choosing t o sel 1 or n o t t o sel l the lease t rac ts .

' T w o o i l sp i l l sizes are considered i n t h i s analysis, those greater than 1,000 barrels and those greater than 10,000 barrels. Tables 9 and 10 show :he probabilities (expressed as percent chance) of one or more o i l sp i l l s (greater than 1,000 barrels and greater than 10,000 barrels) the most l ikely number of o i l sp i l l s , and the expected number of o i l sp i l l s occurring and contacting targets within periods of 3 , 10, and 30 days, over the expected production l i f e of the proposed lease t r ac t s , for onshore and ' offshore transportation scenarios, respectively. Tables 11 t o 16 show similar probabilities for the north, south, and east deletion alternatives (onshore and of fshore transportation scenarios). Tables 1 7 t o 24 show similar probabilities t o l a n d and sea segments for the proposed :ease t r ac t s , north, south, and east deletion a1 tcrnatives (onshore and offshore transportation scenarios).

The overal 1 probabi 1 i t i e s are a1 so shown graphical ly in appendices B and C . Figures 8-1 through 3-41 are histograms which show probabi 1 i t i e s of 1, 2 , . . . N s p i l l s occurring and contacting specific targets within periods of 3 , 10 , and 30 days. Figures C - 1 through C-6 indicat?, through c i rc les superimposed o n maps of t h e coast1 i ne, the probabil i t i e s of one or nore spil 1s occurring and contacting land segments within 3 , 10, and 30 days, for b o t h scenari 0s.

3i scussion of Results

Assuming that oil i s spil led in the lease area, the p r ~ b a b i l i t y o f a sp i l l contacting land within 3 days i s minimal for each launch point. These probabili t ies increase as s p i l l s are tracked up t o 30 days; however, t h e chancss of o i l contacting l a n d are s t i l l no higher than 37 percent (see launch point P4, table 5 ) . Host o f the s p i l l s head i n a westerly direction, contacting the segments a l o n g t h e open sea boundary. Even launch point P8, located very close t o shore near Nome, Alaska, has o n l y a 25-percent chance of contacting l a n d within 30 days. Any s p i l l s that would come ashore would probably a1 so be highly weathered. The shorefast i ce zones also have 1 i t t l e chance of being h i t by an o i l spi l 1 (assuming one occurs) excep t by spil 1s 1 aunched from s i t e s P3 and P4 . The spi 1 1 contact probabilities for ice zones 4 and 5 a re in the range of 40 t o 50 percent (see table 5 ) from these launch points for 3-day travel times.

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t ravel time) i s 51 percent f o r the onshore transportat ion scenario and 53 percent f o r the offshore transportat ion scenario. These probabi l i t ies are reduced by about one-half i f s p i l l s of 10,000 barre ls and l a rger are considered. Land segments 19 and 2 1 , located on the nor th shore of Norton Sound, a re t h e most l ike ly t o be h i t by s p i l l s . The southern and eastern shores have l i t t l e chance of b e i n g contacted by a n oi l s p i l l ; probabi l i t ies of one o r more con tac ts ( s p i l l s of 1,000 barre ls or larger) t o these segments are a l l l e s s than 5 percent. The most l ike ly f a t e of s p i l l s i s t o travel o u t of Nortan Sound, Segment 30, which contains the eastern t i p o f S t . Lawrence Island, has a 33 t o 38 percent chance of being contacted by one o r nore oil spil 1s ( o f 1,000 barrels or l a rger ) within 30 days travel time.

The t a rge t s iflost l ike ly to be effected by o i l s p i l l s are: mid-boundary arza 1 , summer (39 percent chance of one o r Jore s p i l l s , 1,000 barre ls or l a rger , 30 days t r a v e l ) ; mid-boundary area 5 , winter (53 percent); king crab f ishing area, summer ( 3 3 percent); 3nd the gray whale area (SO percent) . (To see the " fu l l ' ' r i sks t o these t a rge t s , these v a l u e s should be multipl i e d by the 14-percent chance that o i l w i l 1 be found.) The seabird foraging areas sliew d i s t i nc t differences i n spi 1 l contact probabi I i t i e s f o r summer and winter. For example, during the sumer , seabi r3 foraging area 3 h a s a 32 percent chance of being contacted by one o r inore s p i l l s ( o f 1,000 barrels or l a rger , 30 days t r a v e l ) . However, during the winter, t h i s probability i s reduced t o l e ss than 0.5 percent.

The north delet ion a l t e rna t ive reduces the r isks t o land by approxinately 40 percznt, The south delet ion a1 ternat ive poses the same risks as the proposed action, s ince only g a s , not o i l , i s assumed present i n the deleted t r a c t s . The eas t delet ion a1 t e rna t ive , which h a s the lowest nstirnate of o i l , reduces r isks t o l a n d by approxinately 30 percent .

Conclusions

This analysis indicates t ha t i f oil ex i s t s i n commercial quant i t ies i n the OCS Lease Sale 57 area , ( a 1 4 percent chance), 2.8 o i l s p i l l s of 1,000 barre ls or larger a r e expected t o occur i n the Norton Sound lease area. The probability t ha t one or more o i l s p i l l s of 1,000 barrels or larger will occur i s 94 percent; the probability of one or nore s p i l l s occurring and contacting land within 30 days i s 51 t o 53 percent , depending upon the t ransportat ion method chosen. For s p i l l s 10,000 barre ls or larger , t hese probabil i t i c , arc rzidced t o 26 t o 27 percent.

The south delet ion a1 t w n a t i v e poszs the same o i l s p i l l r i sks as the proposed a c t i o n . T h e north delet ion a l t e rna t ive reduces r i sks to land by about 40 percent, w h i l e the east del2tion a l ternat ive

. reduces these r isks by a b o u t 3i3 percent (both a l tzrnat ives also reduce the amount of o i l ) . Very l i t t l e difference ex i s t s , a s f a r as oil spi 1 1 r i sks are concerned, setween the onshore and offshore transportat ion scmarios .

Refe rences C i t e d - Danenberger , E.P. , 1976, O i l s p i l l s , 1971-1975, Gulf of

7 e x i c o O u t e r C o n t i n e n t a l She1 f : U.S. Geolog ica l Survey C i r c u l a r 741, 47 p.

1980, O u t e r C o n t i n e n t a l S h e l f o i l and g a s m w o u t s : U.S. Geo log ica l Survey Open-Fil e Repor t

80-101, 1 5 ~ .

Devanney, 3 . W . , 111, and S t e w a r t , R.J., 1974, A n a l y s i s of o i l s p i l l s t a t i s t i c s , Apr i l 1974: M a s s a c h u s e t t s I n s t i t u t e of Technology (Cambridge) r e p o r t no. :dITSG-74-20 p repa red f o r t h e Council on Envi ranmenta l Q u a l i t y , 125 p.

Devanney, J.W,, I11 and s t e w a r t , R.J., 1976, The n o r t h e a s t and o f f s h o r e o i 1 : > d a r t i n g a l e , Inc . , P repa red f o r Brookhaven Nat ional L a b o r a t o r y , Upton, N.Y., 68 p.

L a n f e a r , K. J . , Smi th , R . A * , and S l a c k , J . R . , 1979, An i n t r o d u c t i on t o t h e o i 1 s p i 11 r i sk anal y s i s model : Proczed i ngs o f the O f f s h o r e Technology Conference , l l t h , Houstgn, Tex., 1979, OTC 3607, p . 2173-2175.

L a n f e a r , K.J. and Samuel s , N . B . , 1981, Documentat ion and u s e r ' s gu ide t o t h e U.S. Geo log ica l Survey o i l s p i l 1 r i s k a n a l y s i s zodel : o i l s p i l l t r a j e c t o r i e s and the c a l c u l a t i o n o f c o n d i t i o n a l probabi 1 i t i e s : 3 .S. Geol o g i c a l Survey Open-Fil e Repor t 81-316, 95 p.

L i u , S.K., and Nelson, A.a., 1977, A t h ree -d imens iona l model f a r e s t u a r i e s and c o a s t a l seas: volune V , t u r b u l e n t ene rgy program: T h e Rand C o r p o r a t i o n , R-2187-OWRT, S a n t a Yonica C a l i f . , 90 p.

Oil s p i 1 1 I n t e l l i g e n c e Repor t , 1979, I n t e r n a t i o n a l summary of 1978 s p i l l s ; V . 2 , No. 1 2 , March 23 , 1979, 20 p.

Oi l s p i l l I n t e l 1 i g e n c e R e p o r t , 1980, I n t e r n a t i o n a l sumnary o f 1979 s p i l l s : V , 3 , No. 2 1 , Yay 2 3 , 1980, 32 p.

Smi th , R . A . 9 S l a c k , J.R., Wyant, T . , and L a n f e a r , K.J., 1980, The o i l s p i l l r i s k a n a l y s i s nodel of the U.S. Geo log ica l Survey : U.S. Geo log ica l Survey Open-Fil e Repor t 80-587, 107 p.

S t e w a r t , R.J., 1975, A s u r v e y and c r i t i c a l r ev i ew of U.S. o i l s p i l l d a t a r e s o u r c e s w i t h a p p l i c a t i o n t o the t a n k e r l p i pel i ne c o n t r o v e r s y : Repor t t o t h e U. 5. Depa r tnen t o f t h e I n t e r i o r , ' da sh ing ton , D . C . , , Y a r t i n g a l e Inc., Camsridge, :4ass., 75 p.

S t e w a r t , R . J . , a n d Kennedy, M. B . , 1975, A n a n a l y s i s o f U.S. t a n k e r and o f f s h o r e petroleuo product ion o i l s p i 1 l a g e t h r o u g h 1975: Report t o O f f i c e of ?olicy Analys i s , U . S. Depar tgent o= the I n t e r i o r , Cont rac t Number 14-01-0001-2193, ,Yart i n g a l e Inc . , Cambridge, :4ass., l l l p . .

U .S. Ceol ogical Survey, 1979a, Accidents connected w i t h Federal o i l and g a s o p e r a t i o n s o n t h e Outer Cont inenta l S h e l f , G u l f of Yexic3, V. 1, 1956-1979: U.S. Geological Survey, Conszrvat ion D i v i s i o n , December 1979, 131 p .

1979b, Accidents connected with F e d e r a l o i l and gas o p e r a t i o n s on the Outer Cont inenta l S h e l f , P a c i f i c area: U.S. Geological Survey, Conservat ion D i v i s i o n , 10 p.

1980, O u t 2 r c o n t i n e n t a l she l f s t a t i s t i c s , caTTndar year 1979: 'J.S. Geological Survey, Conservat ion D i v i s i o n , 100 p .

Appendix A .-

E t' ill r m a, % 0

rn vl ill

a o rn L - 6. u

I

u rg a 0 0 'I-

0 C ? c .,--

w 5 LC,

Appendix 3 --..I--

z = ZAST 3CLETlQY - E

N L ~ ~ E R SF CONTACTS &ITFIN 3 D A Y S

F i g u r e 3-1 .--4lstoqr3ns snowing :he ?rgoani l i t i e s .lf s ~ e c ~ f i c iumoers 2 t J I ! 5 5 1 1 1 s (: ,300 3 a r e 1 5 ~ n d ;re:rr: 3cc.;rr? ng 3na :trntactrng ; and 35 3 r%ul : 3 f :j s.:e,3r3oos& 5c::an. ( 2 ; :ye l o e n 3elet:on l i t ? - ~ a t : r e , 3na , 3 ) t n e eas: de1et:on 31:5r?at1ve. for :ne 3nsnor3 :?3ns3or:atron s c e n a r ~ a .

3 EAST DELETION

2 5'-

NORTH 3ELEf!CN 2

NUf'49ER OF CONTACTS 'IdlT?!N 30 9.4YS

NUMSER OF CONTACTS WITulN ;O D A Y S

NUMBER OF CONTACT; WITY!N 3 D A Y S

Figure 3-2.--4istogr3ms s h o w i n g the ~rooaoll 1 t i e s sf j ? e c l f i e numoers 3f s i 1 s p i 11 s (1 ,000 ~ a r r f l s and greater) o c c a r n n g jnd contacting :c= zone s 1 s 2 result af (1) t h e ~ r m o s e d 3ct-on. ( 2 : the nor th jeletion a l :xna t ive , and \ 3 j :fie %st deletion dltcr~attve, 'or the snshore cranspor,atlon scenar~ a .

- - J EAST QELET!ON =I 3

NLiMSER OF CONTACTS 'NITYIN :0 D A Y S

NGMSER OF CONTACTS NITWN 3 DAYS - -

i i g u ~ 3-3.--disto--~rsms s n w l n g :he ~rsbaoilitles 3 f s o e c i i i c numDers 9i ? i : s ~ i 1 !s (1J00 mrreis 3nd jr l3ter) 3ccurnng - ?nd -3n t3c t i ng ma-oounaary jrea 1 ' . j u m e r ) as a r e s u l t OT , L J

:he ~ r o o o s a x r i o n , 2 : :ye I o r r h d e i e t i o n a l t i?rnat :ve, i n a ' 2 ) tne 5 a s t ;lelzc:3n ~izdrnatlve, for the onsnore ' . r a n s 3 0 ~ 3 t i o n scenar*o.

3 a EAST DELET!ON

9 NORTH 9ELFT!ON g

NUFBEFI CIF CONTACTS 1ITk!!N :0 D A Y S

NUt46EP CF CSNTACTS iVIT!+!N 3 DAYS --

Figure 3 - 4 . - - 4 i s t o g r m s showing the 3robaolllties o f suec i f i c numDers ~f o t 1 S D ~ 11 s ( ? ,300 5arrel s jnd jrezter) ccc4~rr1ng 3na contacting md-oounda--< ?ra? 2 ( s m e r ) 35 3 r e s u l t C I ~ , : j the ?reposed aczion, : 2 j :he I O R ~ Z e l e t i o n a i ternat: v e . and ( 3 ) t 3e e a s t 321S570fl 3 l t e r n a t l v e , f o r :he 3nshore t r3nSaorta t lon Scenario.

1 EAST 3 E L T ! C N

C d -

- . : 1 gure 3-5 .--Hi?togr?rns snowing -.ne rotr rani 1 i t i e s o f s p e c i f i c lumbers ,f

3 1 , s a i 11s j! ,3C10 3arrel s ina qreatzr ) accurrt no 3nd contdcring 112-soundary area 3 (silmer) as I. result 3f (!) the grsooseo ! c t -gn , ( 9 ) the n o r t h deletion alternative, and (31 :ae :as: deletion alternative. P J ~ :ne 3nshore transportation jcenarto.

PROPOSAL

NORTH OELETlON 6

= a EAST DE-LET!GN a

NUHBER OF CONTACfS 'NITY!N :0 DAYS

NbM6ER OF CaEITXCTS NITH!N 3 D A Y S

Figure 34 . - -Hi s t~q rm snowrng t7e : r m a i ~ t l 1 t r e s s f sqeclf?c Tunsers >i o i l s s i l l s (1,500 sdrr?ls and j rea te r ) occurnn? 2nd contact:ng md-oounadry jraa 4 , s ~ m e r ) rs 3 resui t 3 i , 1 ) :he Jraoased a c t l o n , , 2 ) t he lort(r ?ele+:Dn 3 l t z m t e . and ( 3 ) the ?as= 3eler:on j l t e r n a t i v e . =or rhe snsnore cranspo=atton scenar-o.

> - - 4 - -

a.3 4

s a.2 - .-. 7 a.. 1 = a.a +

2 NLMBER SF SZNTq iYS qY\T'i!N 30 D A Y 3

NUMSER OF CONTACTS 'NITuIN 3 D A Y S . - . .. . ~ - * r:gure 3-7.--Yistogrms snowing the ~rooaoilities s f j p e c i i i c numoers > f s i 1 x o i 11 s (: .JOO s a r r e l s and g r e a t z r ) occvrr?ng ?nd :sntact?ng 316-?oundarV 3r33 3 (sumer) a s i result o f ::; .Ae 3rmos2a 3c::3n. ( 2 7 :he nor'h de1et:on 31 t ? r ~ a t : v e , and : 3 ) :he ?as: :el?t?on ~lternatlve, igr :he snsnore t ransoortaL!on sc2nar:o.

EAST I)ELET!CN 3

L

NUMBE3 GF CONT.4CTS NITF!N 30 D A Y S

NUMBER OF CONTACTS 'A'ITHIN :0 D A Y S

NUMSER OF CONT.4CTS 8lTHlN 3 D A Y S

Figur? 3-4.--distograms showing t h e s r o o a D i l i t i e s o f spec i f i c numers o f l i 1 s p i 1 1 s ,1,300 barr2i s 3na greater) o c c z r r i ng and con tac t ing ? id -~ounda ry 31-23 ! ( w i n t e r ) 3s s r = s u l t 3 i i!) the ?roposel i c t ? o n , ( 2 ) Lne nor th d e l e t i o n a l t ~ r n a t : v e , 2nd (3) !be 2 3 s ~ d e l e t i o n 31 t e rna t i ue , f o r the Jnsnore : ransoor ta t ion scenar io.

=a EAST 3ELET!CN - -

r=I

Figure 3-3.--di s tograns snowing : y e ~ r m a b ~ 1 i t i e s ~i ;sec!iic ~ u n b e r s s f 3ils~il:s (:,300 lartels 2nd gr~aterj ~ c c u r r ' n y 2nd contact!ng m~a-oounoary 3rea 3 ( ~ u ~ ~ ? ! ? ) 3s 3 f e s i l i t 3 i ':!

: B.3 4 i? a.2

a , 4 &7 1 I,,, - 0.a 1

1 2 NUMBER I)? CCNTr lCTS N I T H N '0 D A Y S

NIjMSER OF CONTACTS WITHIN 3 S A Y S =igure 3-10.--dtstograms snowing :he arobabil~tles o f s p e c ~ f l c lumoers 3f

01 1 spill s (! ,000 3arrels and g r e a t e r ) occsrrl ng and contaczing nid-ooundary area 3 ( w l n t e r ) as a result sf ;1) the prtloosed act' ,:on, ( 2 ) t h e n o e b dclet:on t s rna t ive ,

irans40>iaf10n and ' 3 -be ; ~ ~ ~ a r i ~ i ? r - o n a i ternatire, far '!he inshore

3 EAST DELE'!CN z

1 2 NUMBE4 3F X C N T C T ; HIT!-I!N '0 DAYS

1 2 3 NUMBER OF ZCNTACTS HITU!N 3 O A Y S

''sure 3-11.--rli stograns ;now1 ng the Jrooaoi 1 ltr es st ;?eci ric ,\uiwcrs .J!

01 1 s ~ i 1 1s (: ,230 ~ar -$1 s and g rea te r ) cccurr: ng m a t o n t a c t l n g lid-sounaary 3raa 5 (wintcrl 3s 1 r e s u l t IF ;I) :he srozosed 2ct:on. 2 ) :9e ~ o e h del?r,:on j l t e r n a t ~ v e , and ( 3 ) :ye 22s: Aelet~on altemartve. 'or :he 2nsnore t r3nsgotTJt:on szznar io .

2 EAST DELCilCN ;?

I NUMBE2 OF CON7.4CTS VVITYIN YO D A Y S

r E 1 - 32 4 9 W M

E 3.) j a.a

1

NUMBER OF ZCNTACTS JVIT!-IIN 3 D A Y S

-'igure 3-12 . - -His t~grams s h m l n g the 3rooabilittes o f s p e c ~ f ~ c lumbers of o i l s o i l 1 s ( i ,300 2arrsls ind grea te r ) oc:urrlng ~ n d c3ntact:ng seaolrd f o rag ing 3 r e 3 1 (sumer) 3s ). * ? s u i t of ( 1 ) :he 3rooosed I c t : o n , ( 2 ) tne n o c h d e l e t i o n alc2rvatlve, and ( 3 ) :F,e 2ast delatlon :Iter?dCtve, -3r :?e Onsnore t ransoor ,3 t i on s c e n a r i o .

n PROPOSAL ' 2 EAST DELETION a

I '2

NGMSER !IF SCNTACfS HITuIN 30 DAYS

I 2 NUM6ER DF CONTACTS NlTHlN i0 DAYS

1-, - a.O 2

NUMBER OF CONTACTS #lTHlN 3 DAYS - - - . . - .

Figure 3-13.--Histograms showing the 7ro~abilities o f spec i f i c numbers sf oilspills (1.000 barrels and greater) o c c - r v i n n and con tac t i ng seabird for3ging lrea 7 (sumner) 3s. a resuit 3f

(1) :he omposed ac t ion , ( 2 ) tne n o c h d e i e t t o n a l t z r n a t i v e , and ( 3 ) the z a s t delet ion alternative, f o r the Onshore transportation scenario.

11 PROPOSAL

m a NORTH DELETION @

3 EAST DELETION E2

NUMBER OF CONTACTS *ITFIIN 30 D A Y S

NGMBER OF CONTACTS 'UITHIN 10 DAYS

7- c- d a 4 a g 3.2 j

a.i 4

2 NUMBER OF CONTACTS WITHIN 3 D A Y S

F i g u r e 6-14.--Hi stograms showing the probabil + t i e s of specific numbers o f oilsoil 1s (1,000 oarrels and grea;er) occur r ing and can tac t lng seaoird foraging a rea 3 (sumner! as a result ol (1) the proposed ~ C t i o n , ( 2 ) the north de le t ion a l t e r n a t i v e , and (3) the eas t d e l e t i o n a i t e r n a t i v e , f o r :he Onsnare t r a n s p o r t a t i o n scenar io .

a EAST DELET!ON a

Fa NORTH DELET!CN

32

2 NUMSER OF CCNTACTS 4ITYIN 30 DAYS

r t. 4 m < rS3 Q c 0.1 0.0

1 - 7

NUMBER OF CONTACTS NITHIN iB DAYS

"." 1 b 3

. . . . WHBER OF CONTACTS 'WITYIN J DAYS

f i g u r e 3-15 .--Hi stoarams rhowing the 7robabil i t ies of s ~ e c j f i c numbers of o i l s s i l i s (1,300 b a r r e l s and g r e a t e r ) occurr ing and con tac t ing seabird f o rag lng u.ea 4 (surrmer! 3s.3 result gf ) the pPODOSed Ict:on, ( 2 ) t h e n o c h de le t ion 3 l t e r n a t l v e , and ! 3 ) 'he sast d e l e t i o n a l t e r n a t i v e , f o r :9e snsnore t r a n s p o r t a t ; o n scenar io .

n PROPOSAL B EAST DELETlON

9 NORTH DELETION a

a.0 7

1 NUMBER OF CONTACTS WITHIN 30 DAYS

0.0 /-

1 NUMBER OF CONTACTS WITHIN 70 DAYS

0.0 I

1 NUMBER 3F CONTACTS WITHIN 3 DAYS

Figure 3-16.--Histograms showing the probabilities a f s s e c i f i c nunrbers d f o i l spi 11 s (1,000 barrels and g r e a t e r ) occurring and c ~ v t a c t i n g seabird foraging area 5 (sumner) as a r e s u l t o f (1 ) the praoosed ~ c t i o n , ( 2 ) the nor th d e l e t i o n d l t e m f a t i v e , and ( 3 ) the e a s t d e l e t i o n a l t e r n a t i v e , f o r the anshore Transporta t ion scenario.

EAST 3E;LET!ON B 3 NORTH DELETION E

1 3 *

NUMBE2 OF CONTACTS 'NITSIN 30 BAYS

1 2 NUMBER OF CONTACTS ;YITH!N 10 D A Y 3

r t =! r: 4 a 0 x

a*! a. 0

1 2 NljMBER OF CONTACTS NlTHlN 3 DAYS

Figure 3-17.--ilistograrns showing the probabil i t i e s o f s ~ e c i f i c numbers of o i l sp i 11 s (1.500 b a r r e l s and greater) occurr ing and c?ntact ing seabird foraging area 1 ( w i n t e r ) as. I result o f ( A ) t he proposed ac t ion , ( 2 ) t he n a c h ?elet!cm 3 l t e r n a t r v e . and ( 3 ) the e a s t d e l e t i o n a l t e r n a t i v e . f o r the ansnore t r anspor t a t ion Scenarlo.

1 PROPOSAL I EAST DELETION

NUMBER OF CONTACTS iVlT!-!lN 30 DAYS

NUMBER OF CONTACTS WITHIN 70 DAYS

NUMBER OF CONTACTS 1lTYIN 3 D A Y S

F i g u r e 8-18.--Hi stograms showing the ?robabi 1 i t i e s of speci f ic numbers o f 0i l s p i 11 s (1.000 barre ls and g r e a t e r ) occurring and c o n t a c t i n g seabird foraging area 2 ( w i n t e r ) as a result o i (1) the proposed a c t i o n , ( 2 ) t he n o r t h d e l e t i o n a l t e r n a t i v e . and ( 3 ) t h e easc d e l e t i o n d l t e r n a t ~ v e , f o r t h e o n s h o r e ' r a n s p o r t a t i o n . scenario.

NORTY DELETION Zi

NGMBE.9 OF CONTACTS WITHIN 10 DAYS

NUMBER OF CONTACTS WITHIN 3 DAYS

Figure 8-19.--Histdqr~1~ showing the p r o b a b i l i t i e s o f speci f ic iumoers o f o i 1 sp i 11 s (1.000 b a r r e l s Ind ?rester) occurr ing and contacting King crab a r w (sumner) as 3 result o f ( I ) +he lraposed act ion. : 2 ) the n o r t h d e l e t i o n a l t e r n a t t v e , and ( 3 ) t h e e a s t d e l e t i o n a1 t a r n a t i v e , f o r the onshore transDorcatlon scenario.

n PROPOSAL 3 EAST DELETION 3

9 NORTtl DELETION E3

NUMBER OF CDNTACTS WITHIN 30 D A Y S

NUMBER OF CONTACTS WITHIN i0 DAYS

0.0 1 1 - 9

NUMBER OF CONTACTS IITHIN 3 DAYS i i gure 3-20.--Histo rams showlng 'he probabil ities o f speclric numers o r

o i l splyl s (1 ,Of23 oarreis and greater) occurring and contacting Yukon Delta (sumner) 3s a result ' o f (1) the prooosed action, (2) the north deletion alternative, and ( 3 ) the east deletion alternative, for the onshore transportation scenario.

13 PROPOSAL B EAST DELETION

I 2 3 A NUMSER OF CONTACTS iVlTY!N 30 D A Y S

1 2 3 NUMBER OF CONTACTS IVITH!N 70 DAYS

1 2 3 4

NUMSER OF CONTACTS HITY!N 3 DAYS t lgure 5-LL.--Histogram snowi nq the orooao i 1 i ties o f s p e c i f i c numbers , ~ f

oilspills (1.000 barrels and greater) occurring and c o n t i e t i n g Gray wnale 3rea 3s a result a f (1) the proposed ac t i on , ( 2 ) the l o r t b d e l e t i o n a l t e r n a t i v e , and ( 3 ) t he east d e l e t i o n a l t e r n a t i v e , f o r zhe 3nshore t r a n s p o r t a t i o n scenario.

a EAST DELET'CY a

Figure 3-22.--Histograms showing t h e probantlities o f specific numbers of 01 lsnll 1 s (1,000 barrels and greater) occurring and y o n t a c t i n g land as a result of (1) the ~roposed act ion, , 2 ) the n o r t h d e l e t i o n ~ l t e r n a t i v e , a n d ( 3 ) the a a s t deletion alternat7ve. f o r :he o f f sho re t r a n s p o r t a t i o n scenan o.

EAST 3ELETI:Y 3

r r i - ;= d

?3 I -I

a.B I 1

NGMSER OF CONTACTS HlfH!N 3 DAVS

Figure 3-23.--Histograms snowing the probabi 1 i t i e s o f q e c i f i c numers 3f o i 1 sp i 11s (1,900 b a r e l f and greater) occurr ing and con tac t i ng i c e zone 5 3s a result 3 f ('1) the 2rooosea ~ t i o n , ( 2 ) t 9 e nor th d e l e t i o n a l t e r n a t i v e , and ; 3 ) !he east deletron a l t e r n a t i v e , f o r the of fshore t r a n s p o ~ a t 7 o n scenan o.

B EAST DELETlOrJ

t k -1 ;n 2 a.3 i g 0.2 - ea. i 1 I

a.O - -- - I 7

NljMBER OF CONTACTS h'IT+!N 30 D A V S

d

1 2 NUPSER OF CONTACTS HIT3IN 10 D A v S

1 2 - NLMSER OF CONTACTS iVlfH!N 3 D A Y S

Figure 3-24.--Histograms showing the p r o b a b i l i t i e s o f s p e c i f i c nuroen o f o i l s p i l l s (1,300 barrels and greairr; d c z w r i n g dnd con tac t i ng mid-boundary area ! (sumner) 3 s a result crf (:) the proposed ac t i on , ( 2 ) the n o r t h d e l e t i o n 3lternative, and i3) :he e s t j e l e c i o n alternative, f o r t h e o f f sno re t r a n s p o r t a t i o n scenar io.

NGMSER OF ZONTACTS NITFIN 3k3 D A Y S

NtiMBER OF CONT.4CTS WlTMN 10 D A Y S

t t- i ;n < z 8

a j a.a --.-

1 3 L

NUHSER OF CONTACTS iY173!N 3 DAYS

Cigure 6-25.--Histograms showin4 the ~ r o ' l a o i l i t i e s of soec i f ' c numbers rrf o i 1 spi l l s ;: ,;CU barrel s 3nd greater) o c c ~ r r i ng and contacting nid-ooundary l rea 2 ( s z n c r f as a resul t o f j l ) the ~rooosed action. ( 2 ) the north delet ion al ternat ive. and ( 3 ) the e a s t :elet;an d l te rna t ive , f o r the offsnore tranSDortation jCenarl3:

B EAST 35LET1'3.N

NUMSER tlF CONTACTS 'vVIT!-I!N !0 DAYS

.- NUMBER OF CONTACTS WLTHIN 3 DAYS

F igure 8-25.--Hi stograms showing the probabi 1 i ' c i es o f soec i f i c numbers o f oilrpill s (1.00CY b a r r e l s and grea te r ) occu r r i ng :nd c o n t a c t i n g aid-ooundary area 3 ( s u m e r ) is a result ~f ,:) t h e voposed aczion, ( 2 ) the nor th d e l e t i o n a l t e r n a t i v e , and ( 3 ) the eas t deletion 3lternative, f o r the ~ f f s h o r e EranSportation scenario.

3 EAST DELET!@W

r L - 4

" a.1 4 L. - I 8.0 --

1 2 3 NUMSER SF CONTACTS A'ITYIN 30 D A V S

:igure 3-27.--Histograms showing the rooa abilities o f specific numbers of 3 i l spills (1,300 barrels and g r e a t e r ) occgrrlnq 3nd c3ntaeting mid-uoundary area 1 (sumner) as a result 3 i ( I ) :ne ?mDOsed action, (2) the north deletion alternative, and ( 3 ) the easr delet:on a 1 ternative, f o r the oiisnore EransDor ta t i on scenario.

I EAST DELET!ON

I 2 NLFBER C)F CONTACTS NITY!N 30 D A v S

NUMSER OF CONTACTS i4vVITtl!N :0 DAYS

a.o - - 2

.. - NUMSER OF CONTACTS il(lT?!N 3 D A Y S

~i gut-@ 3-28.--Hi stograms snowing the probaoi 1 i ti es o f spec:fic numbers of o i 1 $ p i 11 s (1,300 barrels and greater) Gccurri ng and contact ing aid-ooundary area 5 (sumer) as a result o f ( 1 ) the Jroposed act ion, ( 2 ) the north deletion alternative. and ( 3 ) t h e east deletion alternative. for the of fshore transportation scenario.

= 3 EAST DELET'QY =

NUMBE.9 OF CONTACTS UVITHIN DAYS

NUMBER OF CONTACTS NITSIN 3 D A Y S F!gure 3-29.--rlistograms showing the prubabi 1 i t i e s of specifqc numbers of

oi l s ~ i l l s (1,000 5arels 3nd greater) ocz2rri?g and c o n t a c t i n g mid-boundary area 1 ( w i n t e r ) 3s. a result g f (1) the proposed action, ; 2 ) the north deletion alternat~ve. 3nd (3) :9e east deletion alternative, f o r the 3f fsnorc trans p o r t a t i o n scenario.

EAST DELETICY 3

NUMBE.9 OF CONTACTS i4ITHIN 30 D A Y S

NUMSER OF CONTACTS WlTL'lN :0 D A Y S

0.0 -- - L.

1 2 W M S E R OF CONTACTS NITV!N 3 D A Y S

Figure 3-30.--Histograms showing the p r o b a b i l i t i e s o f specif ic numbers of o i 1 S P I 11 s (1,000 " y e ! z and g r e a t e r ) s c c u r r i n g an:! con tac t ing qid-boundary area 3 ( w i n t e r ) as d resdit s f (1) the ;~roposed action, ( 2 ) the n o e h d e l e t i o n a l t e r n a t i v e . and ( 3 ) t h e P a s t de t e r ion alternative, f o r the o f f sho re t ransporTat ion scenar io .

EAST 9ELETiOhl a

! 2 NUMBER SF CDNfACTS NITL(!N 30 3.4"s

1 2 NUMSER 3F CENTACTS IITY!N '0 DAYS

A ot < 0 g a.2 4 l a . ; - --

a.0 I - .

1 2 L 3

NUMSER OF S3NfACTS rVIT!+!N 3 D A Y S

Figure 3-31.--4istograms showing t h e probaailities of soecific numbers of 3 i l s p i 1 ; 5 (1,300 barrels and g r e a t e r ) o c c z r r i n g and contact ing imd-boundary a r e a J (w in te r : 3s 3 tesult 3f !1) tne Drooosed act ion. ( 2 ) t 3 e n o r t h l e l e t i o n a l t e r n a t i v e , and (3) the aasz deletion ~lteraative, for t h e onshore t r a n s p o r t a t i o n scenario.

3 EAST 3ELETIOY

1 2 NLMSER CF CONTACTS WIT+i!N 30 DAYS

1 2 NUMSER OF CONTACTS WITr!N :0 D A v S

1 2 NUMBER 3F CONTACTS I l f$ !N 3 D A Y S -- -

F i g u r e 3-32.--Hfstograms showing the p r o b a b i l i t i e s o f s p e c i f i c numbers of o i l s p i l l s (1,JOO barrels and greater) occurr ing and con tac t ing mid-boundary area 3 ( w i n t e r ) a s a r e s u l t 3 i (1) t h e ?reposed ac t ion , ( 2 ) t h e n o r t h d e l e t i o n a l t a r n a t i v e , and ( 3 ) 'he 2 a s t d e l e t i o n a l t e r n a t i v e . f o r She o f f s h o r e t r l n s p o r t a t i o n scenario.

PRCPOSA!. a EAST 3ELEf!ON

9 NCQT? CELETICN

F Z

NCPSEF [3F SONfACTS iYlf3lN :0 DAYS

2

NUMBER CF CONTI\CTS QIT?!N 3 DAYS

Figure a-33.--Hi stograms showing the prwbabil i t i e s of s ~ e c i f i c numbers 3 i o i 1 spi 11 s (1,300 aarrel s and g rea te r ) occurr: ng and con tac t i ng seao i rd fo raq ing area 2 (sumer) -as a result 3f (1) the ~ r o p o s e d nc t i on , ( 2 ) . t h e ?om9 3ele:ion 3lternative, 3115 , 3 ) the zas t d e l e r ~ o n alt~rnative. f o r the o f f s h o r e : ransoortat1 on scenar io.

1 2 NUMBER ClF CCNTACTS IVITq!N 50 D A Y S

r c 1 c2 4 m 0 E "0.1 j

a.0 ' I

1 2 - NUMSER OF CONTACTS WlTHlN 5 D A V S

. .

~i g u i 3-34.--Hi srowarns showing the probaoi 1 i t i es 3 f spec1 f i e numDerS o f o i l s p i 1 1 s (1,000 Sarrels and grea te r ) occnrring and contacting seaoird foraging area 3 (sumner),as 3 result o f ( 1 ) the 3roposed act ion, ( 2 ) :he north delet ion a l te rna t ive , and ( 3 ) the east d e l e t i o n ~lternative. for the offshot-? t ransportat ion scenario.

a PROPOSAL % EAST 3ELETlOhl 3 =I

NUMBER SF CONTAC?S HITYIN :0 DAYS

r 'I-

a.a -.-

1 9 - NtiESER OF CONTACTS NlTHIN 3 D A Y S

F igu re 0-35.---Hi s t o g l p ~ Thowing ',he ~ r u b a b i 1 i t i e s of speci f ic nunOers of i S31 1 300 t r a r ~ l s and r e a t e r ) sc:urrlng and

:Antacting ieiolrd foraging arca 3 : i ~ e r ) 2s r resu l t 1 ) the prooosed act:on, ( 2 ) ,he ndrth delet ton a! ternat ive . and ( 3 ) the east 3elet ion a l t e r n a t i v e . f o r -. the offshore r,ransoorrat;on scenario.

PROPOSAL I EAST 3ELETiGY

b a.1 4 a-a , - 7 1 - -

NCiMBER OF CONTACTS iVlTLi!N 30 3 A Y S

0.0 1 - 1 2

NUMBER OF CONTACTS INlfYlN 70 DAYS

NUMBER OF CLlNTACfS llTHlN 3 DAYS

Figure 3-36.--Histograms sharing the ProbaDil i t i e s o f spec i f i c numoers o f oi 1 s p i l l s (1 ,C70 barrels and g r e a t e r ) occurr ing and ccn26cting seamrd foraginq area 5 ( ~ u m ~ e r ) , 3s a result o f (1) t h e pro~osed act ion. 2 ) the n o r t h d e l e Z i o n a l t e r n a t i v e , and ( 3 ) tne e a s t delerion alternative, f o r t he sffshore t r a n s p o r t a t 1 on scenario.

NUMBER GF CCNT.4CTS 'UIT5IN 30 3.4"s

NUMSER OF CONTACTS JllTulN 3 DAYS

F i g u r e 3-37 .--HI stograms showing the probabilities o f specif i f numers o f o i 1 sp i 11 s ( I , J00 b a r r e l s and greater) s c c u r r i ng and c w t a c t i n g seaoird f o rag ing area 1 ( w ~ n t e r ) as 3 r e s u l t sf (1) cite proposed ac:?on. ( 2 ) The nor th d e l e t i o n a l t e r n a t i v e , and :3) the 2 a s t d e l e t i o n a l t e r n a t i v e , f o r the o f f s h o r e t r a n s p o r t a t i o n scenar!o.

B EAST DELETION

9 NORTH DELET!ON

53

NGMBER OF CDNTPCT3 'NIT!I!N 30 D A Y S

NGMBER Of CONTACTS WI'THIN D A Y S

I C

NUMBER OF CONTACTS .NITHIN 3 DAYS

~ i ~ u r @ 3-38.--iiistograms showing the probabil i t i e s o f specific numers 3 f o i 1 s p l l l s (1,530 barrels and greater) occurri nq 3nd cornact ing seaoird foraging a r e a 2 (winter) as a result g f (1) t h e groposed action, ( 2 ) the north deletion alternative, and ( 3 ) the aast delet ion a1 ternative, f o r the o i f sna re t ransoonat lon scenario.

EAST ELETION B

NUMBER CIF CONTACTS HITUN :0 D A Y S

NLIPSER CIF CGNTACTS WITHIN 3 3.4vS

Figure 3-39.--Hi stogrms showing t h e pPQbaDll i t i e s o f specif ic nurnoers o f oil s ~ i 11 s :1,300 sarrel s and greater) occarri ng and cantacting Ying c r m jred (sumner) as a result o f :1) the prooosed acfion. ( 2 ) :he n o e h d e l e t i o n d i t e r n a t i v e . and ( 3 ) the aast l e l e t t o n a l t e r n a t i v e . f o r the of fshore t r 3 n s p o r t a t i o n scenar io.

r r_ i m 4 m g "2 j

- I 2

NGMBEF OF CONTACTS bVITFIIN 50 9 A Y S

a.0 I - 1 2

NGMBER OF CDNTACTS l lTt i lN 3 DAYS

F i gum 8-40.-Histograms howing the p r o b a b i l i t i e s of s p e c i f i c numbers o f o i l spill s 71,300 barreis and g rea te r ) occurrr ng and contacting Yukon 9elta (sumner) as a , -e?u: t o f (1) the prooosed a f f t o n , ( 2 ) the north delerton a l te rna t ive , 3nd (3) tne e a s t deletion a l te rna t ive , f o r the offshore t ransportat ion scenario.

0 PROPOSAL 3 EAST DELETION

NUMBER 3F CCNTACTS IITF!N '0 DAVS

NUMBE8 OF C3NT.ACTj HITt.IlN 3 DAYS ~i gu& 8-41 .--Histogrmns snowing the ~ r o ~ a n i 1 i t i es of speci f ic numoers o f

01 1 sp i 1 1 s (:,go0 barrels and greater) occurring and cantacting ::27 . ,nale 3re3 as a result a i ( I ) the .reposed action, (2) the l o r t h deletion alrernaiive, and (3) t h e cast deler~on alternative, for t h e o f f s h o r e transportation scenario.

Appendix C --

Figure C-1.--Map showing the probability (percent chance) of one or more spills (1,000 barrels and greater) occurring and contacting sections of the coastline f o r - : 3 davs travel rime, proposed action, onshore transportation scenario.

i

N 06

ALASKA

?ERCEI'iT F=ZO3,-,S:LITV Norton

2 Sound a

St. Lawrence Island

f

Sea

A

Figure C-2.--Map showing t h e p r o b a b i l i t y ( p e r c e n t chance) o f one o r more s p i l l s (1,000 barrels and g r e a t e r ) occurr ing and c o n t a c t i n g s e c t i o n s of t h e c o a s t l i n e f o r 1 0 days travel time, proposed a c t i o n , onshore t r a n s p o r t a t i o n s c e n a r i o .

I PERCENT F)ROSABILITY i

j St. Lawrence

I Island

Norton Sound

Bering Sea

! /'a F i g u r e C-3.--Map showing t h e p r o b a b i l i t y (pe rcen t chance) of one o r more

s p i l l s (1,000 barrels and g r e a t e r ) occurring and c o n t a c t i n g sections of the c o a s t l i n e f o r 30 days t r a v e l t i m e , proposed ac t ion , onshore t r a n s p o r t a t i o n s c e n a r i o .

i S t . Lawrence I s l and

i 1

1 Bering

ABILITY

Sea

Norton 1 Sound

F i g u r e C-4.--Map showing the p r o b a b i l i t y ( p e r c e n t chance) o f one o r more s p i l l s (1,000 b a r r e l s and g r e a t e r ) occur r ing and c o n t a c t i n g s e c t i o n s of t h e c o a s t l i n e f o r . 3 days t r a v e l time, proposed acr ion , of f sho re t r a n s p o r t a t i o n scenario.

Sorton Sound

;St. Lawrence : Island

Figure C-5.--Map showing the probability (percent chance) of one or more s p i l l s (1,000 ba r re l s and greater) occurring and contacting sect ions o f t he c o a s t l i n e f o r : l O days t r ave l time, proposed ac t ion , o f f s h o r e t r anspor t a t ion scenario.

ALASKA

Norton Sound

I I a

i ;: St. Lawrence

Island

Figure C-6.--Map showing the p r o b a b i l i t y (percent chance) of one or more spills (1,000 barrels and greater) occurring and contacting sections of rhe coastline f o r :30 days travel time, proposed action, offshore transportation scenario.