U N I T E D S T A T E S E N V I R O N M E N T A L P R O T E C T I O N A G E N C YR E G I O N 8

999 18™ S T R E E T - SUITE 300D E N V E R , CO 80202-2466

h t t p : / / w w w . e p a . g o v / r e g i o n 0 8

R e f : 8 E P R - E RA C T I O N M E M O R A N D U M A M E N D M E N TS U B J E C T :

AUG 2000

F R O M :

T H R O U G H :

T O :

Request f or a 12-Month Exempt i on f r o m the s t a t u t o r yl i m i t at the U p p e r Arkansas - P l u v i a l T a i l i n g s( C a l i f o r n i a G u l c h N P L ) [ O U 1 1 ] S i t e , L e a d v i l l e , LakeC o u n t y , C o l o r a d o .Mike Zimmerman, OSCEmergency Response T e a mS t e v e H a w t h o r n , S u p e r v i s o r yEmergency Response U:D o u g l a s S k i e , Dire c t orO f f i c e o f Preparednes s^ j£^se^sment, and ResponseM a x Dodson, A s s i s t a n t Regional A d m i n i s t r a t o r - O f f i c eof Eco sys t ems P r o t e c t i o n and Remediat ionS i t e I D # :C a t e g o r y of Removal:

29 ( O U 1 1 )T i m e - C r i t i c a l , N P L

I . P U R P O S EThe purpo s e of thi s A c t i o n Memorandum Amendment i s torequest approval of an ex empt i on f r o m the 12 month s t a t u t o r yl imi t to the Removal A c t i o n ( d a t e d 6 / 1 7 / 9 9 and a t t a c h e d )that is described herein for the U p p e r Arkansas - F l u v i a lT a i l i n g s ( C a l i f o r n i a G u l c h N P L ) [ O U 1 1 ] s i t e ( S i t e ) l o c a t e din L e a d v i l l e , Lake C o u n t y , C o l o r a d o . The Removal A c t i o n wasi n i t i a t e d to addre s s the need to m i t i g a t e the threat po s edby t a i l i n g s with elevated metal concentrat ions of l e a d ,c o p p e r , cadmium, and zinc on riverbanks and in a d j a c e n ts u r f a c e channels threatened by erosion f r o m w a t e r f l o w in theArkansas River. C o n d i t i o n s e x i s t i n g at the S i t e present animminent and subs tantial endangerment to human h e a l t h andthe environment and met the cr i t er ia for i n i t i a t i n g aRemoval A c t i o n under 4 0 C F R , S e c t i o n 3 0 0 . 4 1 5 ( b ) ( 2 ) o f t h eN a t i o n a l Cont ingency P l a n ( N C P ) . T h i s request meets t h eemergency criteria for exemption f r o m the 12-month s t a t u t o r yl i m i t s on a Removal A c t i o n and is necessary because not allthe work can be c o m p l e t e d in 12 months due to a l a t e s tarton the Removal A c t i o n and the short c on s t ruc t i on season inthe mountainous area at the S i t e . A second f i e l d seasonwi l l be needed to f i n i s h r evege ta t i on , i n - s i t u r emed ia t i on ,and evaluat ion of the v e g e t a t i o n .

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I I . S I T E C O N D I T I O N S A N D B A C K G R O U N DA . S i t e D e s c r i p t i o n

1. Removal S i t e Evaluat ionThe approved Removal A c t i o n f o c u s e s upon a seriesof t a i l i n g s along the Arkansas River south of thec o n f l u e n c e with C a l i f o r n i a G u l c h . T h e a t ta chedprevious A c t i o n Memorandum dated June 17, 1999 ,describe s the evaluation which was a c c o m p l i s h e d in Mayof 1999 and the s e l e c t i o n of 3 c r i t i ca l areas f r o m anA l t e r n a t i v e s A n a l y s i s .

2. Physical Loca t i onS e e t h e a t tached A c t i o n Memorandum da t ed 6 / 1 7 / 9 9 .

3. S i t e Charac t e r i s t i c sSee th e at tached A c t i o n Memorandum dated 6 / 1 7 / 9 9 .

4. Release or threatened release into the environmentof a hazardous substance, or p o l l u t a n t orcontaminant.S e e t h e a t ta ch ed A c t i o n Memorandum da t ed 6 / 1 7 / 9 9 .

5. NPL S t a t u sThe S i t e is l o c a t e d on a p o r t i o n of OU11 of theC a l i f o r n i a G u l c h N P L s i te .

6. M a p s , Pi c tur e s , and Other G r a p h i c Repre s en ta t i on sSee A t t a c h m e n t s and S u p p l e m e n t a l R e f e r e n c e s asl i s t e d at the end of th i s A c t i o n Memorandum.

B. A c t i o n s to Date1. Previous A c t i o n s

S e e t h e a t tached A c t i o n Memorandum dat ed 6 / 1 7 / 9 9 .2. Current A c t i o n s

E P A ' s removal contractor h a s d e v e l o p e d a s t a g i n garea for del ivery of r i p - r a p / b i o s o l i d s / l i m e and beganto p l a c e d r i p - r a p on the bank of the river in severall o ca t i on s to prevent f u r t h e r erosion. Some areas arein the process of being revegetated - w i l l ow s are beingadded and a s p r i n k l i n g sys t em is being c o m p l e t e d . S o i l

amendments wi l l be added to p o r t i o n s of the S i t e inp r e p a r a t i o n f o r r evege ta t ion.At th i s time the contrac tor has mob i l i z ed to thesouthern p o r t i o n of the s i t e and is p r e p a r i n g thef l u v i a l t a i l i n g s f o r in-situ treatment involvingt i l l i n g , a d d i n g o f l i m e , compos t and b i o s o l i d s , ande v e n t u a l l y revege ta t ion.S e e t h e a t tached A c t i o n Memorandum da t ed 6 / 1 7 / 9 9f o r t o ta l p o t e n t i a l a c t i v i t i e s .

D. S t a t e and Local A u t h o r i t i e s ' Roles1. S t a t e and Local A c t i o n s to Date

S e e t h e a t ta ched A c t i o n Memorandum da t ed 6 / 1 7 / 9 9 .2. P o t e n t i a l f or Continued S t a t e / L o c a l Response

S e e t h e a t t a c h e d A c t i o n Memorandum da t ed 6 / 1 7 / 9 9 .

III. T h r e a t s t o P u b l i c H e a l t h o r W e l f a r e o r t h e Environment, andS t a t u t o r y and Regula tory A u t h o r i t i e s .R e f e r t o the a t t a c h e d previous A c t i o n Memorandum dated6 / 1 7 / 9 9 .

I V . Endangerment Determinat ionA c t u a l or threatened releases f r o m th i s S i t e , i f no taddre s s ed by i m p l e m e n t i n g the Removal A c t i o n s e l e c t e d in th i sA c t i o n Memorandum, may present an imminent and s ub s t an t ia lendangerment to p u b l i c h e a l t h , or w e l f a r e , or the environment.

V . E X E M P T I O N FROM S T A T U T O R Y L I M I T SA. Emergency Exempt ion:

1. S i t e c ond i t i on s meet the cr i t er ia set f o r t h inC E R C L A § 1 0 4 ( c ) ( 1 ) ( A ) [ 4 0 C F R 300.415 ( b ) ( 5 ) ( i ) &( i i ) o f t h e N C P ] . T h e r e i s a n immediate risk t o p u b l i ch e a l t h or w e l f a r e and the environment as d e t a i l e d int h e a t t a ch ed previous A c t i o n Memorandum dated 6 / 1 7 / 9 9 .2. An exemption f r o m the 12-month s t a t u t o r y l imi t onremoval act ions is necessary because not all the workcan be c o m p l e t e d as i d e n t i f i e d in the a t tached A c t i o nMemorandum, due to a l a t e s tart on the Removal A c t i o n

and the short c on s t ruc t i on season for the mountainousarea at the S i t e . A second f i e l d season wi l l be neededto f i n i s h a p p l i c a t i o n o f soil amendments with lime p l u srevege ta t ion with native s p e c i e s , in- s i t u r emed ia t i on ,and evaluat ion of the v e g e t a t i o n in order to s u p p l e m e n ti t , where needed. If t h i s request f o r an e x empt i onf r o m the 12-month s t a t u t o r y l imi t i s not g r a n t e d , theRemoval A c t i o n and proper r e c lamat ion and r e s t o ra t i oncannot be f u l l y c o m p l e t e d .

V I . Propos ed A c t i o n s a n d Es t imated C o s t sA. Propo s ed A c t i o n s

1. Propos ed A c t i o n D e s c r i p t i o nC o m p l e t e the pre sent Removal A c t i o n as per theA t t a c h e d A c t i o n Memorandum da t ed 6 / 1 7 / 9 9 .

2. Con tr i bu t i on to Remedial Per formanceR e f e r t o th e A t t a c h e d A c t i o n Memorandum d a t e d6 / 1 7 / 9 9 .

3. D e s c r i p t i o n of A l t e r n a t i v e T e c h n o l o g i e sR e f e r t o th e A t t a c h e d A c t i o n Memorandum d a t e d6 / 1 7 / 9 9 .

4. E E / C AR e f e r t o th e A t t a c h e d A c t i o n Memorandum d a t e d6 / 1 7 / 9 9 .

5. A p p l i c a b l e or Relevant and A p p r o p r i a t eRequirements (ARARs)R e f e r t o th e A t t a c h e d A c t i o n Memorandum da t ed6 / 1 7 / 9 9 .

6. P r o j e c t S c h e d u l eIt i s a n t i c i p a t e d that the remaining act ions canbe c o m p l e t e d by Summer of 2001.

B. Es t imated C o s t sNo change.

VII. Expec t ed Change in the S i t u a t i o n S h o u l d A c t i o n be Delayed ornot taken.Delayed act ion w i l l cause a cont inuat ion of the p u b l i ch e a l t h risks of l o a d i n g of heavy me ta l s into the Arkansas River,which w i l l d egrade the river qua l i ty and increase the p o t e n t i a lf o r p u b l i c exposure through inge s t i on o f contaminatedp l a n t s / c r o p s i r r i g a t e d wi th river water that contains high l e v e l sof heavy m e t a l s .

V I I I . O u t s t a n d i n g P o l i c y I s s u e sN o n e

I X . EnforcementR e f e r t o t h e a t tached A c t i o n Memorandum da t ed 6 / 1 7 / 9 9 .

X . RecommendationT h i s d e c i s i on document r epre s en t s an e x empt i on f r o m the 12-month s t a t u t o r y l imi t o f the s e l e c t e d Removal A c t i o n f or theU p p e r Arkansas - F l u v i a l T a i l i n g s ( C a l i f o r n i a G u l c h N P L ) [ O U 1 1 ]S i t e l o ca t ed in L e a d v i l l e , Lake County , C o l o r a d o . T h i s RemovalA c t i o n Amendment has been deve l oped in accordance with C E R C L A , asamended and is cons i s t ent wi th the requirements of the NCP.C o n d i t i o n s a t t h e S i t e meet t h e N C P §300.415 ( b ) ( 2 ) cr i t er iafor a cont inuat ion of the Removal, and I recommend your approvalo f t h e p r o p o s e d Removal A c t i o n cont inuat ion. The p r o j e c t budgetand c e i l i n g w i l l remain the same as in the or ig inal A c t i o nMemorandum.

A p p r o v e : /r<*<pWW*~~——— Dat e: /'/OOM a x H . DodsonA s s i s t a n t Regional A d m i n i s t r a t o rO f f i c e o f Eco sys t ems P r o t e c t i o nand Remedia t ion

Disapprove:_______________________ D a t e ;M a x H . DodsonA s s i s t a n t Regional A d m i n i s t r a t o rO f f i c e o f Ecosys t ems P r o t e c t i o nand Remedia t ion

A t t a c h m e n t s : A t t a c h m e n t 1 - A c t i o n Memorandum da t ed 6 / 1 7 / 9 9 .

S u p p o r t / r e f e r e n c e document s , i n c l u d i n g t h e previous A c t i o nMemoranda and background r e p o r t s , may be f o u n d in theA d m i n i s t r a t i v e Record F i l e a t t h e S u p e r f u n d Records Center f o rRegion V I I I E P A , 9 9 9 18th S t r e e t , Denver, C o l o r a d o 80202.

Attach ml fit IU N I T E D S T A T E S E N V I R O N M E N T A L P R O T E C T I O N A G E N C Y

REGION 8999 18™ S T R E E T - SUITE 500**~^& D E N V E R , CO 80202-2466pncH^

C O N F I D E N T I A LR e f t 8EPR-ER

A C T K

SUBJECT: Request for a Time Cri t i cal Removal A c t i o n at the U p p e rA r k a n s a s - F l u v i a l T a i l i n g s ( C a l i f o r n i a G u l c h N P L ) [ O U 1 1 ]S i t e , L e a d v i l l e , Lake County, Colorado .FROM: Mike Zimmerman, OSC "YYY^Sls^Emergency Response Team ' ^^^T H R O U G H : Steve Hawthorn, Supervise:Emergency Response Unit , ^___

Douglas M. S k i e , Director Wft^-c^ ^enr*—•Preparednes s , Assessment & Emergency Response ProgramTO: Max H. Dodson, Ass i s t an t Regional Admini s t ra t orO f f i c e o f Ecosystem Pro t e c t i on and Remediat ion

S i t e I D # : 2 9 ( O U 1 1 )Category of Removal: Time C r i t i c a l , NPL

I . PURPOSEThe purpos e of thi s A c t i o n Memorandum is to request and, document approval of the Removal A c t i o n described herein fort h e U p p e r Arkansas - F l u v i a l T a i l i n g s ( C a l i f o r n i a Gulch N P L )[ O U 1 1 ] s i t e ( S i t e ) , L e a d v i l l e , Lake County, Colorado.T h i s Removal A c t i o n addresses the response to the threatposed by t a i l i n g s with elevated metal concentrations ofl ead , c opper , cadmium, and zinc on riverbanks and ina d j a c e n t s ur fa c e channels threatened by erosion f r o m thew a t e r f l o w in the Arkansas River. Condi t ions exist ing at theS i t e present an imminent and subs tantial endangerment tohuman heal th and the environment and meet the criteria fori n i t i a t i n g a Time Cri t i ca l Removal A c t i o n under 40 CFR,§300.415 ( b ) ( 2 ) o f t h e N a t i o n a l Cont ingency Plan ( N C P ) .

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I I . S I T E C O N D I T I O N S A N D B A C K G R O U N DA . S i t e D e s c r i p t i o n

1. Removal s i t e evaluat ionThe CERCLIS ID number of the U p p e r Arkansas -F l u v i a l T a i l i n g s S i t e i s C O D 9 8 0 7 1 7 9 3 8 . S i t ec ond i t i on s are such that th i s Removal A c t i o n isc l a s s i f i e d as T i m e C r i t i c a l . The area of thisRemoval A c t i o n f o c u s e s upon 3 areas in a series oft a i l i n g s a long the Arkansas River south of thec o n f l u e n c e with C a l i f o r n i a G u l c h . T h e s e l o c a t i o n sare a d j a c e n t to the present course of the ArkansasRiver, and f l u v i a l t a i l i n g s are eroding into thewater on a d a i l y basis. The erosion of t a i l i n g shas been observed by landowner s , E P A , and manyother p a r t i e s . T h e U . S . Environmental P r o t e c t i o nA g e n c y ( E P A ) tasked t h e S u p e r f u n d T e c h n i c a lAssessment and Response Team (START) to provide ana l t e rna t iv e s ana ly s i s f o r re sponse t o t h e f l u v i a lt a i l i n g s a d j a c e n t to 11 mi l e s of the ArkansasRiver ( S e e Attachment A - A l t e r n a t i v e s A n a l y s i s -U p p e r Arkansas River F l u v i a l T a i l i n g s . LakeCounty . Co lorado [ C o n t r a c t # 6 8 - W 5 - 0 0 3 1 ] - May1 9 9 9 ) ; in T a b l e 1 p a g e s 2 9 - 3 7 th e f l u v i a l d e p o s i t shave been charac t e r i z ed , and in T a b l e 3, page s 38-49 o f the A l t e r n a t i v e s A n a l y s i s . The a l t e rna t iv e sanaly s i s was used to s e l e c t a p p r o p r i a t e areas anda p p r o p r i a t e t e chno log i e s which wi l l reduce theimpact o f f l u v i a l t a i l i n g s d e p o s i t s on the U p p e rArkansas River and i t s f l o o d p l a i n . A l t e r n a t i v e sconsidered inc luded no ac t i on , i n s t i t u t i o n a lc o n t r o l s , in-p la c e s t a b i l i z a t i o n , removal, andriver channel a l t e r a t i o n . Each a l t e rna t iv e wasrated according to e f f e c t i v e n e s s , i m p l e m e n t a b i l i t y ,cos t , and a c c e p t a b i l i t y . The S i t e s , which weres e l e c t e d , are l o c a t e d in three areas of theArkansas River and are d e p i c t e d on p a g e s 39-49 ofthe A l t e r n a t i v e s A n a l y s i s - Attachment A.

2. Physical l o ca t i onThe p o r t i o n of the Arkansas River to which th i sRemoval A c t i o n a p p l i e s is l o c a t e d in Lake C o u n t y ,C o l o r a d o , and begins at the c o n f l u e n c e ofC a l i f o r n i a G u l c h and the Arkansas River. The areais shown on the at tached F i g u r e 1, S i t e L o c a t i o nM a p . A l o n g the segment which was cons idered , theriver is fed by Lake F o r k Creek, Iowa G u l c h ,T h o m p s o n G u l c h , Empire G u l c h , Dry Union G u l c h , BigUnion Creek, S p r i n g Creek , S a w m i l l G u l c h , Box

Creek, and T w o b i t G u l c h . The L e a d v i l l e miningarea is drained by C a l i f o r n i a G u l c h . Severalunnamed w e t l a n d s are l o ca t ed a long the river, andthe river is a d j a c e n t to pr iva t e p r o p e r t y and theSan Isabel N a t i o n a l F o r e s t . T h i s Removal Act ionwil l be conducted at three l o ca t i on s on theArkansas River. The l o ca t i on s are shown inFigure s 9, 10, and 11 of the a t tached A l t e r n a t i v e sA n a l y s i s a s A A - A B - A C - A D - A E - A G - C A - C C - C D - C E - C F - C G -C J - C K - C P - C R - C S - M F - M G - M I - M J - M K - M L - M N - N A - N B - N C - N D -N G - N H - N I - N J - N L - N R - N T a n d N U , a n d d e p i c t e d withs i t e loca t ions o n ' p a g e s 40-47. Areas AA thru AGwil l be treated as one d i s t i n c t l o ca t i on as wi l lareas CA, CC thru CS and areas MF - NU. All areasi d e n t i f i e d will be s ub j e c t to in-situ treatmentinvolving the a p p l i c a t i o n of soil amendments.

3. S i t e characteri s t ic sMine t a i l i n g s f r o m the L e a d v i l l e hi s torical mininga c t i v i t y , transpor t ed by weather events andf l u v i a l processes, were carried downstream viaC a l i f o r n i a G u l c h to the Arkansas River andd e p o s i t e d in many l o ca t i on s a d j a c e n t to the river.Residen t s s ta t e that t a i l i n g sediments were alsot ranspor t ed along irr igat ion channels andr e d e p o s i t e d in f i e l d s in the river val l ey. TheArkansas River is used for recreation, irrigat ionof a g r i c u l t u r a l , and range lands. I r r i g a t i o n ofrangeland and agricul tural land with high metalcontent water may have contributed to elevatedl evel s of metals in animals and p l a n t s . T a i l i n g s ,high in metal concentrations, along riverbankshave reduced or e l iminated riverside vege ta t ion,increasing erosion p o t e n t i a l . H i g h metalconcentrations in stream water can causedegrada t i on o f f i s h h a b i t a t s , recreational areas,and agricul tural land. Areas of high metalcontamination are becoming more accessible asdevelopment encroaches on the U p p e r ArkansasRiver. Extremely high metal l eve l s for s e l e c t edremoval areas are indicated in T a b l e 3, page 39 ofthe A l t e r n a t i v e A n a l y s i s , and in Attachment E,Summary of Phyto t o x i c Concentrat ions . The metall eve l s are many times the a l l owab l e thre sho ld forvegetative growth, thereby l ead ing to s car i f i edareas a d j a c e n t to the river that are eas i ly erodedwith continuous river f l o w s . The a l l owab l econcentration for su c c e s s fu l plant growth forcadium, copper , l e a d , and zinc are; 3 to 8 m g / k g ,60 to 125 m g / k g , 100 to 400 m g / k g , and 70 to 400m g / k g , r e spe c t iv e ly . Manganese has no value

a s s i g n e d . The average t a i l i n g s concentrat ion o fthese e l ement s in the p r o p o s e d remediat ion areasare; 680 m g / k g , 840 k g / m g , 10,900 k g / m g , and3 2 , 9 0 0 k g / m g , r e s p e c t i v e ly with manganese measureda t 7 ,300 k g / m g ( S e e A t t a c h m e n t D ) . T h e s e t a i l i n g sare e s s e n t i a l l y s t e r i l e and w i l l never sus tainp l a n t l i f e in the ir current c ond i t i on . Theconveyance of hazardous ma t e r ia l s into theArkansas River continues unabated. Each weatheror high f l o w event l ead s to f u r t h e r d e g r a d a t i o n ofthe U p p e r Arkansas River.F u r t h e r evidence of the s p o i l e d r iparian areas areevidenced by depre s s ed soil pH l eve l s which arer epre s en t ed in A t t a c h m e n t E. The nineteen ( 1 9 )s treamside t a i l i n g s areas s l a t e d f o r remediat ionhave been analyzed . F o u r (4) were f o u n d in the pH1 to 2 range, f i v e (5) in the pH 2 to 3 range, andf i v e (5) in the pH 3 to 4 range; very d i f f i c u l t ,i f not i m p o s s i b l e growing c o n d i t i o n s for any t y p eo f v eg e ta t i on . S t a n d i n g rainwater ( t a i l i n g sareas) with a pH of 1.0 has been observed a d j a c e n tto the river in many of the p r o p o s e d remediat ionareas, f u r t h e r adding to the environmental insultof the t a i l i n g s . Heavy me ta l s are e a s i l ys o l u b i l i z e d in these ac id i c c ondi t i on s , and thusleach into groundwater and s u r f a c e waters of theArkansas River.

4. Release or threatened release into the environmentof a hazardous substance, or p o l l u t a n t orcontaminantThe meta l s of greatest concern for exposurea t t r i b u t a b l e t o the S i t e are l e a d , c o p p e r ,cadmium, and zinc. Cadmium is c l a s s i f i e d as knownhuman carcinogens for certain routes of exposure,and all f o u r of the m e t a l s are a s soc ia t ed withnoncarcinogenic e f f e c t s on s p e c i f i c organ systems.Human H e a l t h Cri t er iaCadmiumCadmium is a hazardous subs tance as d e f i n e d byS e c t i o n 1 0 1 ( 1 4 ) of C E R C L A . It is a heavy m e t a l ,and has been shown to be a carcinogen in bothanimal s t u d i e s and o c c u p a t i o n a l l y exposed groupsof humans via the inhalat ion route of exposure.No evidence has l inked cadmium to cancer via theinges t ion pathway. The CAG has c l a s s i f i e d cadmiumas a Group Bl - - Probable Human Carcinogen for

4

inha la t i on only based on l i m i t e d evidence ofcarc inogenic i ty in humans f r o m occupationals t u d i e s . Cadmium may a l s o be a human mutagen orteratogen, and thus may a f f e c t the kidneys, bones,l iver, r eproduc t iv e sys t em, r e sp ira tory tract orimmune system. Cadmium inhib i t s t h e b o d y ' sa b i l i t y to absorb es sential e l ement s , such asc o p p e r and calcium, and may lead to d e f i c i e n c i e sof those elements. Exposure to toxic amounts ofcadmium by either inhala t ion or inge s t ion wil lcause cadmium to accumulate in the renal systemand even tua l ly cause kidney f a i l u r e .LeadLead is a hazardous substance as d e f i n e d byS e c t i o n 1 0 1 ( 1 4 ) of C E R C L A . Lead is alsoc l a s s i f i e d as a B2 carcinogen by E P A . T h i sc l a s s i f i c a t i o n is the result of adequate animals t ud i e s d e t e rmin ing that these compounds areprobable human carcinogens. Lead can enter thebody via inges t ion and inhalation. Chi ldr enappear to be the segment of the p o p u l a t i o n atgreatest risk f r o m toxic e f f e c t s o f lead.I n i t i a l l y , lead travels in the blood to the s o f tt i s sues ( h e a r t , l iver, kidney, brain, e t c . ) , thenit g r a d u a l l y red i s tr ibut e s to the bones and t e e thwhere it tends to remain. The most seriouse f f e c t s associated with markedly elevated bloodlead l ev e l s inc lude neurotoxic e f f e c t s such asirreversible brain damage. C h i l d r e n haveexhibited nerve damage, permanent mentalre tardat ion, c o l i c , anemia, brain damage, anddeath.C o p p e rC o p p e r is a hazardous substance as d e f i n e d byS e c t i o n 1 0 1 ( 1 4 ) of C E R C L A . Because many coppercompounds and complex e s are r ead i ly s o lub l e ,copper is among the more mobile heavy metal s insoil and sur face environments. The major processthat l i m i t s the environmental m o b i l i t y of c opperis a d s o r p t i o n to organic mat t er , c lays , and othermaterial s . A t m o s p h e r i c t ranspor t o f coppercompounds can also occur. S u f f i c i e n t data is notavailable for copper to derive a level which wouldpro t e c t against the p o t e n t i a l t o x i c i t y of thiscompound relative to human heal th . H i g h l eve l s ofcopper can be toxic to humans. Exposure tom e t a l l i c copper dust can cause a short-termi l l n e s s similar to metal fume fever that is

charac t er iz ed by c h i l l s , f e v e r , aching m u s c l e s ,dryness of mouth and t h r o a t , and headache.Expo sure to c opper f u m e s can produce u p p e rr e sp i ra t o ry tract i r r i t a t i o n , a m e t a l l i c or sweett a s t e , nausea, metal fume f e v e r , and sometimesd i s c o l o r a t i o n of skin and hair. I n d i v i d u a l sexposed to dust and mi s t s of c o p p e r s a l t s mayexhibit conges t ion of nasal mucous membranes,sometimes of the pharynx, and o c c a s i o n a l l yu l c e r a t i o n wi th p e r f o r a t i o n o f nasal s ep tum. I fs u f f i c i e n t concentrations o f c o p p e r s a l t s reachthe g a s t r o i n t e s t i n a l t r a c t , they act as i r r i t a n t sand can produce s a l i v a t i o n , nausea, v o m i t i n g ,g a s t r i t i s and diarrhea. The i n g e s t i o n of ionicc o p p e r can cause convul s ions , and d e a t h . Chronicexposure may resul t in anemia. C o p p e r s a l t s actas skin i rr i tan t s produc ing an i t ch ing eczema.C o n j u n c t i v i t i s or even u l c e r a t i o n and t u r b i d i t yof the cornea may resul t f r o m direc t contact ofionic c o p p e r wi th the eye. U s i n g a v a i l a b l eo r g a n o l e p t i c data f o r c o n t r o l l i n g unde s i rab l et a s t e and odor q u a l i t y of ambient water, thee s t imat ed level is l m g / L . It should berecognized that o r g a n o l e p t i c d a t a , as a basis fore s t a b l i s h i n g as a water q u a l i t y cri teria havel i m i t a t i o n s , and have no d emon s t ra t ed r e l a t i o n s h i pt o p o t e n t i a l adverse human h e a l t h e f f e c t s .ZincZinc is a hazardous substance as d e f i n e d byS e c t i o n 1 0 1 ( 1 4 ) of C E R C L A . Zinc can occur in bothsu spended and d i s s o l v e d f o r m s . It is mobile inboth aquatic systems and in so i l . Atmospher i ct ranspor t of zinc i s a l s o p o s s i b l e . However ,except near sources such as s m e l t e r s , zincconcentrations in air are r e l a t i v e l y low andf a i r l y cons tant . S i n c e it is an e s s en t ia lnu tr i en t , zinc is s t r o n g l y b ioac cumula t ed even inthe absence of abnormal ly high ambientconcentrat ions . It does not appear to beb i o m a g n i f i e d . Z i n c is one of the most importantm e t a l s in b i o l o g i c a l sys tems.Z i n c may be i n d i r e c t l y important with regard tocancer since its presence seems to be necessaryf or the growth o f tumors. I n g e s t i o n o f excessiveamounts of zinc may cause f e v e r , vomit ing, stomachcramps, and diarrhea. Fumes of f r e s h l y - f o r m e dzinc oxide can p e n e t r a t e d e e p into the a lv eo l i andcause metal fume f ever . Zinc oxide dust does notproduce th i s d i s order . Contac t wi th zinc c h l o r i d e

B.

can cause skin and eye i rr i ta t i on . I n h a l a t i o n ofmi s t s or fume s may i r r i t a t e the r e sp ira tory andg a s t r o i n t e s t i n a l t ra c t s . Zinc in excess of 0.25%in the diet of rats causes growth retardation,hypochromic anemia, and d e f e c t i v e minera l iza t i onof bone. No zinc t o x i c i t y is observed at dietaryl ev e l s l e s s than 0.25%. S t u d i e s with animals andhumans ind i ca t e that metabol i c changes may occurdue to the interact ion of zinc and other me ta l s inthe d i e t . Exposure to cadmium may cause changesin the d i s t r ibu t ion of zinc, with increases in theliver and kidneys , organs where cadmium alsoaccumulates . Excessive intake of zinc may causec o p p e r d e f i c i e n c i e s and result in anemia.I n t e r a c t i o n of zinc with iron or lead may al solead to changes that are not produced when themeta l s are inges ted i n d i v i d u a l l y .Other A c t i o n s to Date1. Previous actions

Other Removal Actions within Operable Unit 11 andand along the Arkansas River in the C a l i f o r n i aG u l c h are d i s cu s s ed in the C a l i f o r n i a G u l c h A c t i o nMemoranda dated March 7, 1 9 8 6 ; October 28, 1993;November 1. 1994; S e p t e m b e r 15, 1997; and August4, 1998. A l s o , the waiver for s ta tutary maximum of$ 2 , 0 0 0 , 0 0 0 for Removal A c t i o n s was approved perA c t i o n Memoranda, dated June 24, 1997. Thef o l l o w i n g summary l i s t s Fund Lead Removalsi n i t i a t e d , or p e r f o r m e d , to date for C a l i f o r n i aGulch N P L S i t e :Previous S u p e r f u n d Removal Act ions - Fund Lead

C a l i f o r n i a G u l c h N P L S i t eOperable Unit -Proposed Act ion

OU 2 DMGTI-N T C R2 ) L M G -TCR3 ) M T T -T C R4 ) M G T I -T C R

A c t i o n Memo -Cost C e i l i n g$ 3 7 4 , 0 0 0$480,000

$90 ,000$105,670

Action Memo -Approval DateS e p t e m b e r 10,1993August 9, 1995August 9, 1996A p r i l 15, 1998

Continued - Nex t Page

Operable U n i t -P r o p o s e d A c t i o nou 6 DHTI-

T C R2 ) 5 T h S t -S t a r rD i t c h -T C R3 ) Hamms -PenroseT C R4 ) M W P - P 1

N T C R5 ) M W P - P 2

N T C R6 } R E S # 1 - T P

N T C R7 ) R E S # 1 - T PAmendm ' tN T C R8 ) R E S # 1 - P 3

N T C ROU 7 1) ApacheEnergy &Mineral -T C ROU11 D M a e s t a sW e l l s -ER2 ) RiverTgs

ER3 ) R i v e r T g sER4 ) R i v e r T g sT C R5 ) R i v e r T g sT C R -Amendm ' tCumulat ive T o t a l

A c t i o n Memo -Cos t C e i l i n g$ 5 0 , 0 0 0$ 5 0 , 0 0 0

$ 2 , 7 2 6 , 0 0 0

$ 7 , 2 9 0 , 0 0 0 *Amendment

$ 8 5 , 0 0 0$ 2 4 0 , 0 0 0

Amendment$ 6 0 , 0 0 0

$ 2 0 , 2 4 2

$ 5 0 , 0 0 0$ 5 0 , 0 0 0

$ 1 , 1 2 5 , 0 0 0Amendment**

$ 1 2 , 7 1 0 , 9 1 2

A c t i o n Memo -S i g n e d DateNovember 9, 1995May 1, 1996

J u l y 2 6 , 1996

J u n e 24, 1997J u l y 1 5 , 1998October 26, 1998June 2, 1999

June 2, 1999

Augus t 6, 1996

March 7, 1986

October 28, 1993November 1, 1994S e p t e m b e r 1 5 , 1 9 9 7August 4, 1998

* Waiver o f S t a t u a t o r y $ 2 , 0 0 0 , 0 0 0 Limit f or Removals.** T w e l v e ( 1 2 ) Month Exempt ion Approva l forS e p t e m b e r 15, 1997 Removal A c t i o n .Propos ed A c t i o n LeaendER : Emergency RemovalTCR : T i m e C r i t i c a l RemovalNTCR : N o n - T i m e Cri t i ca l Removal

8

2. Current actionsOther than monitoring of the S i t e , there are noother actions being taken or p r o p o s e d other thanthose discussed in this Act i on Memorandum.Continued response act ions are required toprevent, l i m i t , or mi t iga t e continued to loadingof heavy meta l s into the Arkansas River and thesurrounding v a l l e y . A l o n g with p o t e n t i a l threat sto w i l d l i f e and p l a n t s , this erosion will degraderiver qual i ty and increase the p o t e n t i a l forp u b l i c exposure to heavy m e t a l s through inge s t i onof contaminated p l a n t s / c r o p s irrigated withcontaminated water. W i t h conversion of land useas a result of the Lake County Open S p a c eI n i t i a t i v e (LCOSI), large t rac t s o f land wil l b eopen to p u b l i c access under the control andmanagement of the C o l o r a d o S t a t e Department ofParks. The Arkansas River Ranch and the HaydenRanch, compri s ing 5 ,200 acres of f o r m e r l yp r i v a t e l y owned land a d j a c e n t to the river, arebeing opened to p u b l i c access for recreation andf i s h i n g during the summer of 1999. Propos edremoval areas M F - M G - M I - M J - M K - M L - M N - N A - N B - N C - N D - N G -NH-NI-NJ-NL-NR-NT and NU are l o ca t ed on theArkansas River Ranch. P o t e n t i a l for humanexposure to e levated me ta l s wi l l occur withoutthi s p r o j e c t .

S t a t e and Local A u t h o r i t i e s * Roles1. S t a t e and local actions to date

Residen t s in the Arkansas River f l o o d p l a i n haveobserved dead vegetat ion a d j a c e n t to the riverover the last seventy years. Land owners believethat irrigat ion water, carrying metal l oads f r o mthe Arkansas River and C a l i f o r n i a Gulch havecaused dimini shed u s a b i l i t y of f a r m andrangelands . The e f f e c t s o f the Arkansas Riverwater qual i ty on f i s h and w i l d l i f e have been andcontinue to be s tudi ed by the U. S. F i s h andW i l d l i f e Service ( U S F W S ) . I n recent years t h eLake County S o i l Conservation Dis tr ic t (LCSCD) hasbrought these concerns to E P A .Under the l e a d e r s h i p of the Lake County S o i lConservation Dis t r i c t (LCSCD), a p u b l i c f orum ha sbeen created for the purpo s e of addr e s s ing the

current c o n d i t i o n of the U p p e r Arkansas River. Agroup o f s t a k e h o l d e r s involving local landowner s ,LCSCD, s ta t e and f e d e r a l natural resourcet r u s t e e s , pr iva t e i n d u s t r y , and EPA was f o r m e d andis known as the U p p e r Arkansas River R e s t o r a t i o nP r o j e c t S t a k e h o l d e r s CORE Team. Regular monthlym e e t i n g s are conduc t ed wi th s t a k e h o l d e rr e p r e s e n t a t i v e s invited to a t t e n d and p a r t i c i p a t e .E P A , a l though suppor t iv e o f t h e re s torat ion e f f o r ti n s p i r i t , c o n f i n e d i t s e f f o r t s t o a d d r e s s i n g t h ehazardous m a t e r i a l s wi thin t h e f l u v i a l t a i l i n g s .2 . P o t e n t i a l f o r continued S t a t e / l o c a l response

As d i s cus s ed above repre s enta t ive s of S t a t e andCounty agencie s are concerned about the c ond i t i on se x i s t i n g at the S i t e ; however, they do not havethe f u n d s to conduct the needed removal ac t ions .S u p p o r t for the Removals has been expre s s ed by theLake County S o i l Conservat ion D i s t r i c t , LakeCounty Board of County Commi s s i oner s , p r iva t elandowners , and the U p p e r Arkansas RiverR e s t o r a t i o n P r o j e c t S t a k e h o l d e r s Core T e a m .I I I . T H R E A T S T O P U B L I C H E A L T H O R W E L F A R E O R T H E E N V I R O N M E N T , A N D

S T A T U T O R Y A N D R E G U L A T O R Y A U T H O R I T I E SA . T h r e a t s t o Publ i c H e a l t h o r W e l f c

The c o n d i t i o n s at the S i t e pre sent an imminent andsub s tant ia l endangerment to human h e a l t h and theenvironment and meet the cr i t er ia for i n i t i a t i n g aRemoval A c t i o n under 4 0 C F R §300.415 ( b ) ( 2 ) o f t h e N C P .T h e f o l l o w i n g f a c t o r s f r o m §300.415 ( b ) ( 2 ) o f t h e N C Pf o r m t h e basis f o r E P A ' s d e t e r m i n a t i o n o f t h e threatp r e s e n t e d , and the a p p r o p r i a t e action to be taken:1. "Actual or p o t e n t i a l exposure to nearby animalsor the f o o d chain f r o m hazardous subs tances orp o l l u t a n t s or contaminants" - water f r o m the Riveri s used for i r r i g a t i o n and c a t t l e / o t h e r animals f e e don p l a n t s which are i r r i g a t e d ;2. " H i g h l e v e l s of hazardous substances orp o l l u t a n t s or contaminants in s o i l s l a r g e l y at ornear the s u r f a c e , that may migrate" - t a i l i n g s atthe riverbank had a p o t e n t i a l for migrat ion toareas which h e r e t o f o r e did not have contaminateds o i l .3. "Weather c ond i t i on s that may cause hazardoussubs tances or p o l l u t a n t s or contaminants to

10

migrate or be released" - storm events a n d / o r theS p r i n g r u n o f f may cause the Arkansas River to riseand acce l erate the p o t e n t i a l threat s which arel i s t e d above.B. T h r e a t s to the Environment

S p e c i f i c threats to w i l d l i f e and p l a n t s which canalready be seen have been reviewed under " S i t eC h a r a c t e r i s t i c s " and a d d i t i o n a l damage to w i l d l i f e inthe a d j a c e n t habi tat s and the f i s h in the c on f lu enc ewaters could result f r o m the continued exposure tocontamination either through direc t contact with thee f f l u e n t s , s tanding water, s ed imen t s , or i n d i r e c t l y -through consumption of organisms ( a l g a e , aquaticinsec t s , or animals) f e e d i n g in the area.C o p p e rMean acute t ox i c i ty values for a large number off r e s h w a t e r animals range f r o m 7.2 u g / L for daphniap u l i c a r i a t o 10,200 u g / L f o r t h e b l u e g i l l . T o x i c i t ytends to decrease as hardness, a l k a l i n i t y , and totalorganic carbon increase. Chronic values are availablefor 15 f r e s h w a t e r spec ie s and range f r o m 3.873 u g / L to60.36 u g / L for northern pike. F i s h and invertebratespec ie s seem to be about equally sensitive to thechronic t ox i c i ty of copper.An example of t o x i c i t y to l i v e s t o ck is evident byexposure to sheep. S h e e p are very su s c ep t ib l e tocopper t ox i co s i s , and poisoning may be acute orchronic. Acute po i s oning is caused by direct action ofcopper s a l t s on the g a s t r o i n t e s t i n a l t rac t , r e su l t ingin ga s t r o en t e r i t i s , shock, and death. The toxic doseis about 200 m g / k g and is u sua l ly obtained throughacc idental overdose of an an t ih e lmin th i c . I n g e s t i o n ofexcess c o p p e r over a period of time r e su l t s in theadsorp t ion and accumulation of copper by the liver.T h i s type of chronic cumulative po i soning may suddenlydeve l op into an acute hemolyt i c crisis . C o p p e r intakeof 1.5 g / d a y for 30 days is known to be f a t a l for manybreeds of sheep. Excessive copper may be stored in theliver as a result of excess copper ingest ion, as aconsequence of impaired liver f u n c t i o n , or inconnection with a d e f i c i e n c y or excess of other traceelements.LeadLead is ubiquitous in the environment and althoughbioaccumulation is known to occur, and lead is found in

11

the t i s s u e of many wi ld a n i m a l s , i n c l u d i n g b i r d s ,mammals, f i s h e s , and inver t e bra t e s , the most p u b l i c i z e de f f e c t s of l ead have been on the impact of i n g e s t i o n oflead by w a t e r f o w l . Acut e and chronic lead t o x i c i t yhave been demons t ra t ed as a d e f i n i t e threat to birdp o p u l a t i o n s . Chronic values for daphnia magna and therainbow trout are 12.26 and 83.03 u g / l i t e r ,r e s p e c t i v e l y , at a f r e s h w a t e r hardness of about 50m g / l i t e r . F r e s h w a t e r algae show an inhib i t ion ofgrowth at lead concentrat ions above 500 u g / l i t e r .T h e r e is evidence that l e a d , at concentrat ionso c c a s i o n a l l y f o u n d near r o a d s i d e s and s m e l t e r s , cane l i m i n a t e p o p u l a t i o n s of bacteria and f u n g i on l e a fs u r f a c e s and in so i l . Many of the microorganisms p l a ykey ro l e s in the de compos er f o o d chain. Cases of l eadp o i s o n i n g have been r epor t ed for a varie ty of d o m e s t i can imal s , i n c l u d i n g c a t t l e , horse s , d o g s , and cats.Several t y p e s of man-made sources are c i t ed as thesource of lead in these report s . Because of theirc u r i o s i t y , and their i n d i s c r i m i n a t e ea t ing h a b i t s ,c a t t l e experience the grea t e s t inc idence o f leadt o x i c i t y among d o m e s t i c animals.CadmiumLaboratory exper iment s sugge s t that cadmium may haveadverse e f f e c t s on r e p r o d u c t i o n in f i s h at l e v e l spre sent in l i g h t l y t o m o d e r a t e l y p o l l u t e d waters. Noadverse e f f e c t s on domes t i c or wi ld animals wererepor t ed in the s t u d i e s reviewed.Z i n cZinc produces acute t o x i c i t y in f r e s h w a t e r organismsover a range of concentrat ions f r o m 90 to 5 8 , 1 0 0u g / l i t e r , and appear s to be l e s s tox i c in harder water.A c u t e t o x i c i t y i s s imi lar f or f r e s h w a t e r f i s h andinvertebrate s . A f i n a l acute-chronic ratio f orf r e s h w a t e r spec ie s of 3.0 has been repor t ed . Zincp o i s o n i n g has occurred in c a t t l e . Some researchershave s p e c u l a t e d that exposure to excessive amounts ofzinc may c o n s t i t u t e a hazard to horses. Laboratorys t u d i e s and f i n d i n g s in f o a l s l i v i n g near l e a d - z i n csmel ters suggest that excessive exposure to zinc mayproduce bone changes, j o i n t a f f l i c t i o n s , and lameness.To f u r t h e r demons trat e th e environmental insult f r o mt h e f l u v i a l t a i l i n g s , t h e p h y t o t o x i c c h a r a c t e r i s t i c s o fcadmium, c opper , l e a d , and zinc are presented inA t t a c h m e n t D. The metal concentrat ions present are manyt imes the maximum recommended l e v e l s , thus p r e s e n t i n g ah o s t i l e environment for p l a n t growth. All o f the areas

12

s e l e c t ed for Removal Act ion s or revegetation have metall ev e l s exceeding the maximum recommended values byorders of magnitude. For example , average zinct a i l i n g s l ev e l s have been measured at 3 2 , 9 0 0 m g / k g witha peak concentrat ion of 115,000 m g / k g for the propo s edareas. The maxmium recommended level for zinc tosustain a h e a l t h y p lant environment is 70 - 400 m g / k g .The t a i l i n g s are overwhelmingly s t er i l e .*«.

I V . E N D A N G E R M E N T D E T E R M I N A T I O NActua l or threatened releases of hazardous subs tances ,p o l l u t a n t s and contaminants f r o m this S i t e , i f not addres sedby i m p l e m e n t i n g the response action described in this A c t i o nMemorandum, present a p o t e n t i a l imminent and sub s tant ia lendangerment to p u b l i c h ea l th , or w e l f a r e , or theenvironment.

V . PROPOSED A C T I O N S A N D E S T I M A T E D C O S T SA. Proposed Actions

1. Proposed action de s cr ip t i onT h i s Removal A c t i o n is d e s igned to addre s s thethreat posed by an es t imated 7,800 cubic yards oft a i l i n g s with high concentrations o f l e a d ,cadmium, copper, and zinc which have beent ranspor t ed a n d / o r are eroding into the ArkansasRiver. The actions for each of the areas sub j e c tto this Removal are l i s t e d in the A l t e r n a t i v e sA n a l y s i s (Attachment A) , and involve thea p p l i c a t i o n of soil amendments with lime p l u srevegetat ion with native s p e c i e s , or in-si turemediation, for areas AA thru AG f CA and CC thruCS, and MF thru NU.

2. Contr ibut ion to remedial per formanceThe Removal A c t i o n wi l l not i n t e r f e r e with anyf u t u r e Remedial A c t i o n on the S i t e .

3. Des cr ip t i on of a l t ernat ive t e chnologie sT h e U . S . Environmental Pro t e c t i on Agency ( E P A )tasked the S u p e r f u n d Technical Assessment andResponse Team (START) to provide an al ternativesanalysis for response to the f l u v i a l ta i l ing sa d j a c e n t to 11 mile s of the Arkansas River ( S e eAttachment A - A l t e r n a t i v e s A n a l y s i s - U p p e r

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Arkansa s River F l u v i a l T a i l i n g s . Lake County.C o l o r a d o ) . T h i s a l t e rna t iv e s ana ly s i s was used tos e l e c t a p p r o p r i a t e areas and a p p r o p r i a t et e c h n o l o g i e s which wi l l reduce the impact off l u v i a l t a i l i n g s d e p o s i t s on the U p p e r ArkansasRiver and i t s f l o o d p l a i n . A l t e r n a t i v e sconsidered included no ac t ion, i n s t i t u t i o n a lc o n t r o l s , i n - p l a c e s t a b i l i z a t i o n , removal, andriver channel a l t e ra t i on . Each a l t ernat ive wasrated ac cord ing t o e f f e c t i v e n e s s ,i m p l e m e n t a b i l i t y , c o s t , and a c c e p t a b i l i t y . Ther e su l t s of thi s analysi s indi ca t ed that i n - p l a c es t a b i l i z a t i o n u t i l i z i n g soil amendments wi th l imeis recommended due to the ir lower cost ande f f e c t i v e n e s s at s imi lar s i t e s .Comments f r o m the Colorado Department of Pub l i cH e a l t h and the Environment, the C i t y of Aurora,and the U . S . F i s h and W i l d l i f e Serv i c e have beenreceived. A Respons ivene s s Summary, as perA t t a c h m e n t E has been pr epar ed to addr e s s theconcerns expressed in comments received to theA l t e r n a t i v e A n a l y s i s .

4. E E / C AT h i s Removal A c t i o n is a T i m e C r i t i c a l ResponseA c t i o n and an E E / C A is not required. AnA l t e r n a t i v e A n a l y s i s o f viable op t i on s wasp e r f o r m e d to a l l o w for input f r o m the locallandowner s , the Lake County S o i l Conservat ionD i s t r i c t , local governments, the S t a t e o fC o l o r a d o , pr ivat e indu s t ry , other F e d e r a lA g e n c i e s , and. the general p u b l i c .

5. A p p l i c a b l e or relevant and a p p r o p r i a t erequirements (ARARs)Because thi s A c t i o n is being conducted as a T i m eC r i t i c a l Removal A c t i o n , all F e d e r a l and S t a t eARARs have not been i d e n t i f i e d at th i s time. AnyARARs that have been i d e n t i f i e d wi l l be met to theextent p r a c t i c a b l e , given the exigencie s of thes i t ua t i on . A t en ta t iv e l i s t of ARARs is a t tachedf o r in format ive purpose s .

B. Est imated Cos t sCost E s t i m a t e : A tab l e containing cost e s t i m a t e s forthe Removal p r o j e c t c e i l ing for OU 11 is shown below:

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Extramural C o s t s t

ERRSMater ia l Acqui s i t i on( B i o s o l i d s / C o m p o s t )S T A R T CostCont ingencyT O T A L , E X T R A M U R A L C O S T SIntramural C o s t s tIntramural Direct Cos t sIntramural I n d i r e c t C o s t sT O T A L , I N T R A M U R A L C O S T S

Est . C o s t sT o Date$450,000$ 25 ,000$ 80,000

E s t . C o s t sT h i s A c t i o n$ 3 5 0 , 0 0 0$175,000$ 70,000$ 89 .250

ProposedCost ( E s t )

$$$

800,000200,000150,000

8 9 . 2 5 0$ 5 5 5 , 0 0 0

$ 30,000$ 60.000$ 90,000

T O T A L - R E M O V A L PROJECT C E I L I N G $645,000

$ 6 8 4 , 2 5 0 $ 1 , 2 3 9 , 2 5 0

$ 45,000 $ 75,000$ 40.000 $ 100.000$ 85,000 $ 175,000$ 7 6 9 , 2 5 0 $1,414,250

V I . E X P E C T E D C H A N G E I N T H E S I T U A T I O N S H O U L D A C T I O N B E DELAYED O RNOT TAKENIf no action is conducted at the S i t e , increased l oad ing ofheavy meta l s into the Arkansas River and the surroundingval ley will continue to occur. A l o n g with po t en t ia l threatsto w i l d l i f e and p l a n t s , this erosion will degrade riverquali ty and increased the po t en t ia l for publ i c exposure toheavy metal s through ingest ion of contaminated p l a n t s / c r o p si rr igated with contaminated river water. T h i s action coversonly 19 areas of 149 contaminated l o ca t i on s i d e n t i f i e d inthe f l u v i a l p la in . V a l u a b l e i n f o r m a t i o n wi l l be generatedf r o m this Removal Act i on that will u s e f u l in f u t u r eremediation work on the U p p e r Arkansas River.

V I I . O U T S T A N D I N G P O L I C Y I S S U E SN o n e .

V I I I . E N F O R C E M E N TAttachment B is a c o n f i d e n t i a l summary of the enforcementstatus.

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I X . R E C O M M E N D A T I O NT h i s d e c i s i o n document r epre s en t s the s e l e c t e d RemovalA c t i o n f o r t h e U p p e r Arkansas G u l c h - F l u v i a l T a i l i n g s( C a l i f o r n i a G u l c h N P L ) S i t e , i n t h e L e a d v i l l e , Lake Coun ty ,C o l o r a d o , d e v e l o p e d in accordance wi th C E R C L A as amended,and not in con s i s t en t with the NCP. T h i s d e c i s i on i s basedon the a d m i n i s t r a t i v e record for the S i t e .C o n d i t i o n s a t t h e S i t e meet t h e N C P § 3 0 0 . 4 1 5 ( b ) ( 2 ) cr i t er iafor a Removal A c t i o n , and I recommend your a p p r o v a l . Thet o t a l p r o j e c t c e i l i n g for th i s a c t i on i s e s t imat ed to be$ 1 , 4 1 4 , 2 5 0 and of t h i s , an e s t ima t ed $ 6 1 4 , 2 5 0 comes f r o m theRegional removal allowance.

A p p r o v e : Date:M a x H . DodsonA s s i s t a n t Regional A d m i n i s t r a t o rO f f i c e o f Ecosystems Prot e c t i onand Remedia t ion

Disapprove: Date:M a x H . DodsonA s s i s t a n t Regional A d m i n i s t r a t o rO f f i c e o f Eco sys t ems P r o t e c t i o nand Remediat ion

A t t a c h m e n t s :Attachment AAttachmen t BA t t a c h m e n t CA t t a c h m e n t DA t t a c h m e n t EA t t a c h m e n t F

A l t e r n a t i v e s A n a l y s i s (Contrac t # 6 8 - W 5 - 0 0 3 1 )Enfor c emen t S e c t i o nARARsP h y t o t o x i c C h a r a c t e r i s t i c s SummaryRespons ivenes s SummaryPropo s ed 1999 S o i l A m e n d m e n t / R e v e g e t a t i o nS i t e s , S o i l p H A n a l y s i s

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