### SDM S Document I D


### 47962 5



## RECOR D O F DECISIO N OPERABL E UNI T 5 EGW A SITE S CALIFORNL 4 GULC H SUPERFUN D SIT E LEADVILLE

, COLORAD O OCTOBER 200 0 U.S

. Environmenta l Protectio n Agenc y 9 9 9 18t h Street

, Suit e 50 0 Denver

, Colorad o 8020 2

### RECOR D O F DECISIO N OPERABL E UNI T 5 EGW A SITE S CALIFORNI A GULC H SUPERFUN D SIT E LEADVILLE

, COLORAD O T h e U.S

. Environmenta l Protectio n Agenc y (EPA ) present s thi s Record o f Decisio n (ROD ) fo r Operabl e Uni t 5 (OU5 ) o f th e Californi a Gulc h Superfun d Sit e i n Leadville

, Colorado. 1 

### Thi s include s sla g an d non-residentia l an d residentia l are a soil s fo r Elgi n Smelter

, Grant/Unio n Smelter

, Wester n Zin c Smelte r an d Arkansa s Valle y Sout h Hillsid e Sla g Pil e site s (collectivel y know n a s t h e "EGWA " sites)

. Th e RO D i s base d o n th e Administrativ e Record fo r OU 5 EGW A sites , includin g th e Remedial Investigation/Feasibilit

y Stud y (RI/FS)

, th e Propose d Plan

, the ! publi c comment s received
, an d EP A responses

. Th e ROD present s a brie f summar y o f th e RI/FS

, actua l
an d potentia l risks t o human healt h an d th e environment , an d th e selecte d remedy

. EP A followe d t h e Comprehensiv e Environmenta l Response

, Compensation

, an d Liabilit y Act
, a s amended
, th e Nationa l Contingenc y Pla n (NCP)

, an d EP A guidanc e (EPA

, 1999 ) i n preparatio n o f th e ROD

. T h e thre e purpose s o f th e RO D ar e to : 1

. Certif y tha t th e remed y selectio n proces s was carried ou t in accordanc e wit h th e requirement s o f th e Comprehensiv e Environmenta l Response

, Compensation

, an d Liabilit y Act
, 4 2 U.S.C

. 960 1 e t seq. , as amende d b y th e Superfun d Amendment s a n d Reauthorizatio n Ac t (collectively
, CERCLA)

, and
, t o th e exten t practicable
, 

### t h e NCP ; :


### 2

. Outlin e th e engineerin g component s an d remediatio n requirement s o f th e Selecte d Remedy ; and 3

. Provid e th e publi c wit h a consolidate d sourc e o f informatio n about th e history
, characteristics
, an d ris k pose d b y th e condition s o f OU 5 EGW A sites , as wel l as a summar y o f th e cleanu p alternative s considered
, thei r evaluation
, th e rational e behin d th e Selecte d Remedy

, an d th e agencies consideratio n

of
, an d response s t o the comment s received

. : T h e RO D i s organize d int o thre e distinc t sections : I 

### 1

. Th e Declaratio n sectio n function s as a n abstrac t fo r th e ke y informatio n containe d i n the RO D and i s the sectio n o f the RO D signe d b y the EP A Regiona l • Administrator

. 2

. Th e Decisio n Summar y sectio n provide s a n overvie w o f th e OU 5 EGW A characteristics
, th e alternative s evaluated
, an d th e analysi s o f thos e options

. Th e Decisio n Summary als o identifie s th e Selecte d Remed y an d explain s ho w th e 

### remed y fulfill s statutory requirements ; an d
3

. Th e Responsivenes s Summar y sectio n addresse s publi c comment s receive d o n t h e Propose d Plan

, th e RI/FS

, an d othe r informatio n i n th e Administrativ e Record

.DECLARATIO NDECLARATIO N SIT E NAM E AN D LOCATIO N 

### Operabl e Unit 5 EGW A Site s ; Californi a Gulc h Superfun d Site Leadville

, Colorad o 

### CERCLIS2COD98071793 8 STATEMEN T O F BASI S AN D PURPOS E 

### Thi s decisio n documen t present s th e Selecte d Remed y fo r Operabl e Uni t (OU ) 5 Elgi n Smelter

, Grant/Unio n Smelter

, Wester n Zin c Smelte r an d Arkansas Valle y Sout h Hillsid e Sla g Pil e site s (collectivel y know n a s th e "EGWA " sites ) withi n th e Californi a Gulc h Superfun d Site : ("th e Site") 

### i n Leadville

, Colorado

. Th e Environmenta l Protectio n Agency (EPA ) selecte d th e remed y i n accordanc e wit h Comprehensiv e Environmenta l Response

, Compensation

, an d Liabilit y Act
, 4 2 U.S.C

. 960 1 e t seq., as amende d b y th e Superfun d Amendment s an d Reauthorizatio n Ac t 

### (collectively
, CERCLA)

, an d t o th e exten t practicable
, th e Comprehensiv e Environmenta l Response

, Compensation

, an d Liabilit y Act
, a s amended
, th e Nationa l Contingenc y Pla n (NCP ) i i Thi s decisio n i s based o n th e Administrativ e Record fo r OU 5 EGW A site s withi n th e Californi a 

### Gulc h Superfun d Site

. Th e Administrativ e Recor d (o n microfilm ) an d copie s o f key document s a r e availabl e fo r review a t th e Lak e Count y Publi c Library

, locate d a t 111 5 Harriso n Avenu e in 

### Leadville

, Colorado

, an d a t th e Colorad o Mountai n Colleg e Library

, i n Leadville

, Colorado

. Th e complet e Administrativ e Recor d ma y als o be reviewe d a t th e EP A Superfun d Record Center

, locate d a t 99 9 18t h Street

, 5t h Floor

, Nort h Terrac e i n Denver

, Colorado

. T h e State o f Colorad o ha s been consulte d throughou t th e preparatio n o f thi s Recor d o f Decisio n (ROD)

. Th e State is awar e o f EPA' s selecte d remed y an d ha s chose n t o mak e n o furthe r comment

.

: ASSESSMEN T O F TH E SIT E 

### T he respons e actio n selecte d i n thi s RO D i s necessar y t o protec t publi c healt h o r welfar e o r th e environmen t fro m actua l o r threatene d release s o f contaminant s fro m th e OU 5 EGW A sites , 

### which ma y presen t a n imminent an d substantia l endangermen t t o publi c healt h o r welfare

. DESCRIPTIO N OF TH E SELECTE D REMED Y 

### Thi s RO D specificall y addresse s th e portio n o f OU 5 tha t include s slag
, non-residential'an d residentia l are a soil s a t th e EGW A sites

. Th e OU 5 EGW A site s ar e on e o f 1 1 OU s withi n th e Sit e identifie d a s sourc e areas
. Th e remainin g portion s o f OU 5 (th e "AV7CZL " sites ) wil l b e addresse d separately

. Th e OU 5 EGW A site s includ e slag
, non-residentia l an d residentia l are a soil s fro m forme r smelte r sites

. Pursuan t t o th e Augus t 26 , 199 4 Consen t Decre e a t th e Californi a 

### Gulc h Superfun d Site

, it wa s agreed tha t th e decisio n o n remediatio n o f Site-wid e Surfac e Wate r D - l

### a n d Groundwate r (i.e.
, OU12) woul d b e mad e onl y afte r record s o f decisio n fo r sourc e 

### remediatio n wer e selecte d an d implemente d a t eac h OU

. Remedia l action s selecte d fo r th e OU 5 EGW A site s ar e consisten t wit h th e ASARCO

, Inc

. wor k are a managemen t pla n (WAMP)

. 

### T h e Selecte d Remed y is th e Institutiona l Control s Alternative
, which wa s presente d i n th e Fina l Focuse d Feasibilit y Stud y Repor t (FFS ) (McCulley

, Fric k & Gilman

, Inc.[MFG]

, 1999)

. Th e FF S 

### evaluate d an d screene d remedia l alternative s retaine d i n th e site-wid e Screening Feasibilit y Stud y (EPA

, 1993 ) fo r sla g an d non-residentia l are a soils

. Non-residentia l area soil s ar e define d a s soil 

### in area s currentl y zone d agricultural/forest
, recreational
, highway/business
,

retai l core , commercial
, an d industria l mining

. Fo r th e purpos e o f th e FF S an d ROD

, non-residentia l area 

### soil s wer e evaluate d instea d o f bot h non-residentia l an d residentia l are a soil s becaus e n o residence s ar e locate d within th e OU 5 EGW A sites

. However
, it i s reasonabl y anticipate d tha t som e o f the site s ma y b e occupie d a s residentia l lan d us e i n the futur e base d o n the current residentia l zoning

. T h e FF S use d a comparativ e analysis t o evaluat e fou r alternative s an d identif y th e advantage s an d 

### disadvantage s o f each

. Selectio n o f th e Institutiona l Control s Alternativ e wa s base d o n thi s analysis

. Th e Selecte d Remed y consist s o f measures t o provid e informatio n t o curren t and/o r futur e lan d owner s regardin g th e environmenta l condition s a t th e sit e throug h a zonin g ''overla y district. " an d t o ensure tha t i f th e sit e i s develope d an y necessar y specia l precaution s o r requirement s ar e followed

. An y sampling o r respons e action s wil l be conducte d o r funde d b y ASARC O Inc.
, consisten t wit h th e developmen t plans

. Th e Selecte d Remed y i s protectiv e o f 

### human healt h an d th e environment , an d is considere d effectiv e becaus e (1 ) sla g i n it s existin g conditio n doe s no t presen t a significan t ris k t o human healt h o r th e environment , (2 ) n o significan t pathway s fo r transpor t o f contaminant s o f concer n (COC ) fro m soi l o r othe r environmenta l medi a hav e been identified
, (3 ) th e EGW A site s ar e currentl y vacant ; however
, th e site s ma y intermittentl y b e used fo r recreation

. On e sampl e locatio n a t th e Elgi n Smelte r sit e ha s been identifie d as havin g lea d an d arseni c concentration s in soil tha t excee d th e actio n leve l fo r recreationa l use
. Th e Elgi n Smelte r sit e i s privat e propert y an d wil l be evaluate d in 200 1 as par t
o f th e five-yea r sit e review, an d (4 ) a s th e lan d us e changes
, th e institutiona l control s wil l ensur e tha t wast e lef t in plac e wil l b e addresse d t o preven t exposur e t o huma n health

. STATUTOR Y DETERMINATION

S T h e Selecte d Remed y is protectiv e o f human healt h an d th e environment , complie s wit h Federa l
a n d Stat e requirement s that ar e legall y applicabl e o r relevan t an d appropriat e t o th e remedia l action , is cost effective
, an d utilize s permanen t solution s t o th e maximu m exten t practicable

. Th e remed y fo r th e OU 5 EGW A site s doe s no t satisf y th e statutor y preferenc e fo r treatmen t a s a principa l elemen t o f th e remed y becaus e variou s treatmen t option s considere d earl y i n th e feasibilit y stud y proces s fo r slag
, non-residentia l area soils
, an d residentia l are a soil s were determine d t o b e eithe r technicall y impracticabl e and/o r no t cost effective

. Becaus e thi s remed y 

### wil l resul t i n hazardou s substances
, pollutants
, o r contaminant s remainin g o n sit e abov e health

base d level s tha t wil l allo w fo r unlimite d us e an d unrestricte d exposure , a statutor y revie w wil l b e conducte d withi n fiv e years afte r initiatio n o f remedia l actio n t o ensur e tha t th e remed y is , o r wil l b e

. protectiv e o f human healt h an d th e environment

. Thi s remed y is acceptabl e t o th e communit y o f Leadville

. D-2R O D

DAT A CERTIFICATIO N

CHECKLIS T 

### T h e following informatio n i s include d in th e Decisio n Summar y sectio n o f thi s ROD

. Additiona l 

### informatio n ca n be foun d i n th e Administrativ e Record fo r thi s site

. • COC s an d thei r respectiv e concentrations

. 

### •

. Baselin e ris k represente d b y the COCs

. • Cleanu p level s establishe d fo r COC s an d th e basi s fo r thes e levels

. • Ho w source material s constitutin g principa l threat s ar e addressed

. 

### • Current an d reasonabl y anticipate d futur e lan d us e assumption s use d i n th e baselin e ris k assessment s an d ROD

. 

### • Potentia l lan d us e tha t wil l b e availabl e at the sit e a s a resul t o f the Selecte d Remedy

. • Estimate d capita l costs , annua l operatio n an d maintenanc e costs , an d tota l presen t wort h costs , discount
, rate, and the number o f year s ove r whic h the remed y cos t 

### estimate s ar e projected

. • Ke y factor s tha t le d t o selectin g th e remedy

.

M ax H

. Dodso n Dat e 

### Assistan t Regiona l Administrato r Ecosystem s Protectio n an d Remediatio n U.S

. Environmenta l Protectio n Agency
, Regio n VII I

D- 3

### DECISIO N SUMMAR Y

### TABL E OF CONTENT S SECTIO N PAG E



### 1 . 0 Sit e Name
, Location

, an d Descriptio n
.................................. . DS- 1 2 . 0 Operabl e Unit Histor y an d Enforcemen t Activitie s
.................... .

. :



### ... . DS- 4 3 . 0 Highlights o f Communit y Participatio n
.................................. . DS- 6 

### 4 . 0 Scop e an d Rol e o f Operabl e Uni t

...................................... . DS- 8 5 . 0 Summar y o f Sit e Characteristic s
....................................... . DS- 9 

### 5 . 1 Physica l Characteristic s
...................................... . DS- 9 5.1. 1 Summar y o f Soi l an d Smelte r Wast e Materia l Samplin g - Elgi n Smelte r
........................................ . DS- 9 5.1. 2 Summary o f Soi l an d Smelte r Wast e Materia l Samplin g - Grant/Unio n Smelte r
................................... . DS- 9 5.1. 3 Summary o f Soi l an d Smelte r Wast e Materia l Samplin g - Wester n Zin c
........................................ . DS- 9 5.1. 4 Summary o f Samplin g - Arkansa s Valle y Sout h Hillsid e Sla g Pil e
. DS-1 0 

### 5 . 2 Ground-wate r an d Surfac e Wate r Qualit y
........................ .

DS-1 0 5.2. 1 Elgi n Smelte r
....................................... . DS-1 0 5.2. 2 Grant/unio n Smelte r
.................................. . DS-1 1 

### 5.2. 3 Wester n Zin c Smelte r
................................. . DS-1 1 5.2. 4 Arkansa s Valle y Sout h Hillsid e Sla g Pil e
................... .

DS-1 1 5 . 3 Histori c an d Cultura l Resources
............................... .

DS-1 2 

### 6 . 0 Curren t an d Potentia l Futur e Lan d Us e
.....................'........... .

DS-1 3 7 . 0 Summar y o f Sit e Risk s
............................................. . DS-1 4 7 . 1 Huma n Healt h Risks
..................................... . i

. . . DS-1 4 7.1. 1 Medi a an d Contaminant s o f Concer n ....................!..

.

DS-1 5 7.1. 2 Exposur e Assessmen t

.............................. .

|

. . . DS-1 5 7.1. 3 Ris k Characterizatio n ...............................;.. . DS-1 5 

### 7 . 2 Ecologica l Risks
......................................... ;



### . . . DS-1 7 7.2. 1 Medi a an d Contaminant s o f Concer n
.................. .

. ; 

### . . . DS-1 8 7.2. 2 Exposur e Assessmen t

...............................'.. .

DS-1 8 7.2. 3 Ris k Characterizatio n
.................................. . DS-1 8 7 . 3 Summary o f Risks/Basi s o f Actio n ...........................;.. .

DS-1 9 

### 8 . 0 Remedia l Actio n Objective s
...................... .

................'.. .

DS-2 0 9 . 0 Descriptio n o f Alternative s
......................................... . DS-2 1 DS- iTABL E O F CONTENT S (continued ) 

### SECTIO N PAGE

10. 0 Summar y o f Comparativ e Analysi s o f Alternative s
....................... .

DS-2 4 

### 10. 1 NC P Evaluatio n an d Compariso n Criteri a
....................... .

DS-2 4 10.1. 1 Threshol d Criteri a
................................... . DS-2 4 10.1. 2 Primar y Balancin g Criteri a
............................. .

DS-2 4 10.1. 3 Modifyin g Criteri a
.................................... . DS-2 5 

### 10. 2 Evaluatin g th e Alternative s wit h th e NC P Criteri a
.................. .

DS-2 5 10.2. 1 Overal l Protectio n o f Huma n Healt h an d th e Environmen t

...... . DS-2 5 10.2. 2 Complianc e wit h Applicabl e o r Relevan t an d Appropriat e Requirement s
....................................... . DS-2 6 10.2. 3 Long-ter m Effectivenes s an d Permanenc e
................. .

DS-2 6 10.2. 4 Reductio n o f Toxicity

, Mobility
, o r Volum e Throug h Treatmen t

. . DS-2 6 

### 10.2. 5 Short-ter m Effectivenes s
............................... . DS-2 6 10.2. 6 Implementabilit y
..................................... . DS-2 6 10.2. 7 Cos t

.............................................. . DS-2 7 

### 10.2. 8 Stat e Acceptanc e
.................................... . DS-2 7 10.2. 9 Communit y Acceptanc e
............................... . DS-2 7 

### 11. 0 Principa l Threa t Waste s
........................................... . DS-2 8 12. 0 Selecte d Remed y
............................................... . DS-2 9 

### 12. 1 Rational e fo r Selecte d Remed y
................................ . DS-2 9 12. 2 Descriptio n o f Selecte d Remed y
............................... .

DS-3 0 12. 3 Estimate d Remed y Cost s
.................................... . DS- 3 1 12. 4 Expecte d Outcom e o f th e Selecte d Remed y
...................... .

DS-3 1 13. 0 Statutor y Determination s
...................... .

.................. .

DS-3 2 13. 1 Protectio n o f Huma n Healt h an d th e Environmen t

................ .

DS-3 2 13. 2 Complianc e wit h ARARs
.................................. . DS-3 2 

### 13. 3 Cos t Effectivenes s
......................................... . DS-3 3 13. 4 Utilizatio n o f Permanen t Solution s an d Alternativ e Treatmen t Technologie s ( O r Resourc e Recover y Technologies) t o th e Maximu m Exten t Possibl e
. DS-3 3 13. 5 Preferenc e fo r Treatmen t a s a Principa l Elemen t

............. .

.... . DS-3 3 13. 6 Five-Yea r Revie w Requirement s
. . .............. .

............ .

DS-3 3 

### 14. 0 Documentatio n

o f Significan t Change s
................................ . DS-3 4 15. 0 Reference s
..... . ......... . ..... . ........ . .. . ........... .

. . DS-3 5 

### APPENDI X A Responsivenes s

Summar y DS-i i

### LIS T OF FIGURES 

### FIGUR E


### 1 Genera l Locatio n Map
, Californi a Gulc h Superfun d Site

, Leadville

, Colorad o 2 Californi a Gulc h Superfun d Sit e an d Operabl e Units

, Leadville

, Colorad o 3 OU 5 EGW A Sites

, Californi a Gulc h Superrun d Site

, Leadville

, Colorad o 4 Elgi n Smelte r Locatio n an d Sit e Features

, Operabl e Unit 5, Californi a Gulc h Superrun d Site

, Leadville

, Colorad o 5 Grant/Unio n

Smelte r Locatio n an d Sit e Features

, Operabl e Unit 5, Californi a Gulc h 

### Superrun d Site

, Leadville

, Colorad o 6 Wester n Zin c Smelte r Locatio n an d Sit e Features

, Operabl e Unit 5, Californi a Gulc h Superfun d Site

, Leadville

, Colorad o 

### 7 Arkansa s Valle y Sout h Hillsid e Sla g Pil e Locatio n an d Sit e Features

, Operabl e Uni t 5 , Californi a Gulc h Superfun d Site

, Leadville

, Colorad o 

### 8 Result s o f Investigation s a t th e Elgi n Smelte r Site

, Operabl e Uni t 5, Californi a Gulc h Superrun d Site

, Leadville

, Colorad o 

### 9 Result s o f Investigation s a t th e Grant/unio n Smelte r Site

, Operabl e Uni t 5 , Californi a 

### Gulc h Superfun d Site

, Leadville

, Colorad o 1 0 Result s o f Investigation s a t th e Wester n Zin c Smelte r Site

, Operabl e Uni t 5 , Californi a Gulc h Superfun d Site

, Leadville

, Colorad o 

### 1 1 Result s o f Investigation s a t th e Arkansa s Valle y Smelte r Sout h Hillsid e Sla g Pil e Site

, Operabl e Unit 5 , Californi a Gulc h Superrun d Site

, Leadville

, Colorad o 1 2 Huma n Healt h Sit e Conceptua l Mode l - Leadvill e an d Stringtow n Residents

, Minin g an d O r e Processin g Waters
, Californi a Gulc h Superfun d Site

, Leadville

, Colorad o 1 3 Conceptua l Sit e Mode l fo r Residentia l Exposure

, Californi a Gulc h Superfun d Site

, 

### Leadville

, Colorad o 

### 1 4 Conceptua l Mode l fo r Californi a Gulc h Ecologica l Assessmen t fo r th e Terrestria l Ecosystem

, Californi a Gulc h Superfun d Site

, Leadville

, Colorad o

DS-ii iLIS T O F TABLE S TABL E


### 1 Result s o f Surfac e Wate r Analyse s fo r Georgi a Gulc h an d Evans Gulch

, OU 5 EGW A 

### Sites

, Californi a Gulc h Superfun d Site 2 Summar y o f Comparativ e Analysi s o f Remedia l Alternatives
, OU 5 EGW A Sites

, Californi a Gulc h Superfun d Site 3 Summar y o f Potentia l Chemical-Specifi c

ARARs

, OU 5 EGW A Sites

, Californi a Gulc h 

### Superfun d Sit e 4 Summary o f Potentia l Location-Specifi c

ARARs

, OU 5 EGW A Sites

, Californi a Gulc h 

### Superfun d Sit e 

### 5 Summary o f Potentia l Action-Specifi c ARARs

, OU 5 EGW A Sites

, Californi a Gulc h Superfun d Sit e 

### 6 Detaile d Cos t Estimate : Alternativ e 2 - Institutiona l Controls

, OU 5 EGW A Sites

, Californi a Gulc h Superfun d Site 

### 7 Presen t Wort h Analysis : Alternativ e 2 - Institutiona l Controls

, OU 5 EGW A Sites

, Californi a Gulc h Superfun d Site

DS-i vLIS T O F ACRONYM S AN D ABBREVIATION

S 

### AO C 

### ARA R Asarc o AWQ C 

### BAR A C D CO M 

### CDPH E CERCL A C F R CO C C Z L 

### EGW A E P A ER A F E C F S F F S 

### Colde r f f l H Q 

### LCCH P M F C 

### mg/k g mg/ L M K

m m N CP N P L NRH P O & M 

### O U P C PR P R A R I RiVff i RO D 

### S F S 

### SPL P T B V TCL P 

### Administrativ e

Orde r o n Consen t Applicabl e o r Relevan t an d Appropriat e Requirement s ASARC O Incorporate d ; Ambien t Wate r Qualit y Criteri a 

### Baselin e Aquati c Ecologica l Ris k Assessmen t Consen t Decree Cam p Dresse r & McKe e Inc

. 

### Colorad o Departmen t o f Publi c Healt h an d Environmen t Comprehensiv e Environmenta l Response

, Compensatio n an d Liabilit y Ac t Cod e o f Federa l Regulation s Contaminant s o f Concer n 

### Colorad o Zinc-Lea d Elgi n Smelter

, Grant/Unio n Smelter

, Wester n Zin c Smelter

, an d Arkansa s Valle y Sout h Hillsid e Sla g Pil e 

### U

. S

. Environmenta l Protectio n Agenc y Ecologica l Ris k Assessmen t Foothil l Engineerin g Grou p Feasibilit y Stud y 

### Focuse d Feasibilit y Stud y Golde r an d Associate s Hazar d Inde x 

### Hazar d Quotien t Lak e Count y Communit y Healt h Progra m McCulley

, Fric k & Gilman

, Inc

. 

### Milligram s pe r kilogra m Milligram s pe r lite r Morriso n Knudse n Corporatio n 

### Millimete r Nationa l Oi l an d Hazardou s Substance s Pollutio n Contingenc y Pla n 

### Nationa l Prioritie s Lis t Nationa l Registe r o f Histori c Place s Operatio n an d Maintenanc e 

### Operabl e Unit Primar y gri d 

### Potentiall y Responsibl e Part y Ris k Assessmen t Remedia l Investigatio n
. Reasonabl e Maximu m Exposur e Recor d o f Decisio n Screenin g Feasibilit y Stud y 

### Syntheti c Precipitatio n Leachin g Procedur e Toxicit y Benchmark Value s Toxicitv Characteristi c Leachin a Procedur e DS- vLIS

T O F ACRONYM S AN D ABBREVIATION

S (continued )


### I D S Tota l

Dissolve d Solids T S S Tota l

Suspende d Solids U AO Unilatera l

Administrativ e Orde r U C L Uppe r

confidenc e limi t o f th e arithmeti c mea n 

### USD C U

. S

. Distric t Cour t W C C Woodward-Clyd

e Consultant s \iS/L Microgram s

pe r lite r |im Micro n 

### umhos/c m Micromho s

pe r centimete r

DS-v i1 . 0

SIT E NAME

, LOCATION

, AN D DESCRIPTIO N 

### Operabl e Uni t 5 EGW A Site s Californi a Gulc h Superfun d Site Leadville

, Colorad o CERCLI S # COD98071793 8 T h e Californi a Gulc h Superfun d Sit e ("the Site" ) is locate d i n Lak e County

, Colorado

, i n th e uppe r Arkansa s River basin
, approximatel y 10 0 mile s southwes t o f Denve r (se e Figur e 1)

. Th e 

### stud y are a a t th e Sit e encompasse s approximatel y 16. 5 squar e mile s an d include s th e towns o f Leadvill e an d Stringtown

, a portio n o f th e Leadvill e Histori c Minin g District

, an d th e portio n o f t h e Arkansa s River fro m it s confluenc e wit h Californi a Gulc h downstrea m t o th e Lak e For k Cree k confluence

. T h e Californi a Gulc h Superfun d Sit e ha s been organize d int o 1 2 operabl e unit s (OU)

. Figur e 2 show s th e Sit e stud y are a boundarie s an d th e locatio n o f th e 1 2 OU s within th e Californi a Gulc h 

### Superfun d Site

. Th e U.S

. Environmenta l Protectio n Agenc y (EPA ) i s th e lea d agenc y fo r activitie s a t th e Californi a Gulc h Superfun d Sit e an d is supporte d b y th e Stat e o f Colorad o throug h th e Colorad o Departmen t o f Publi c Healt h an d Environmen t (CDPHE)

. ASARC O 

### Incorporate d (ASARCO)

, a potentiall y responsibl e part y (PRP)

, is financin g th e remedia l action s 

### a t OU5

. O U S include s fou r smelte r site s (Elgi n Smelter

, Grant/Unio n Smelter

, Wester n Zin c Smelte r an d 

### Arkansa s Valle y Sout h Hillsid e Sla g Pile ) a s shown i n Figur e 3

. Thi s Record o f Decisio n (ROD ) specificall y addresse s th e slag
, non-residentia l an d residentia l are a soil s fo r Elgi n Smelter

, Grant/Unio n Smelter

, Wester n Zin c Smelte r an d Arkansa s Valle y Sout h Hillsid e Sla g Pil e sites , collectivel y know n a s th e "EGWA " sites

. Th e remainin g portio n o f OU5

, whic h include s th e 

### Arkansa s Valle y Smelte r an d Colorad o Zinc-Lea d Mil l sites , wil l b e addresse d separately

. T h e Elgi n Smelte r sit e i s locate d in north-centra l Leadvill e o n th e sout h ban k o f Bi g E\>an s Gulc h


### nea r th e intersectio n o f U.S

. Highwa y 2 4 an d State Highwa y 91

. Th e Elgi n Smelte r sit e operate d intermittentl y fro m 187 9 unti l 1903

. Material s a t this sit e consis t primaril y o f sla g pile s an d sla g 

### veneer, an d minor amount s o f smelte r debris an d coke/coal

. Th e Elgi n Smelte r feature s ar e show n in Figur e 4

. Th e estimate d tota l volum e o f sla g an d sla g veneer i s approximatel y 1,00 0 cubic yards

. Th e volum e o f smelte r debri s ha s no t been estimated

. Currentl y th e Elgi n Smelte r sit e is vacant

. Th e sit e is locate d withi n th e Busines s zonin g distric t (i.e.
, commercial/industrial

) establishe d b y th e Lak e Count y Boar d o f Count y Commissioner s (Lak e County

, 1997) ! 

### T h e Grant/Unio n Smelte r site , whic h wa s actuall y tw o separat e smelters
, is locate d nea r th e confluenc e o f Georgi a Gulc h an d Californi a Gulc h an d northeas t o f th e Colorad o Mountai n Colleg e campus

. Th e Gran t Smelte r operate d fro m 187 8 t o 188 2 an d th e Unio n Smelte r operate d intermittentl y fro m 1892 t o 1900

. Currently

, smelte r wast e materia l identifie d a t th e sit e consist s o f a smal l sla g pile locate d t o th e northwes t o f th e forme r smelter
, a relativel y large r sla g pile apparentl y place d f o construc t a railroa d grad e tha t crosse s th e site , scattere d area s o f slag veneer , a n d cok e and/o r coal locate d t o th e northeas t o f th e forme r smelter

. Th e Grant/Unio n Smelte r DS- 1feature s

ar e show n i n Figur e 5

. Th e volum e o f th e sla g pile locate d t o th e northwes t o f th e forme r smelte r i s estimate d a t 5,20 0 cubi c yards

. Base d o n aerial photography
, th e volum e o f th e slag a t 

### the abandone d railroa d grad e i s estimate d t o b e 63,50 0 cubi c yards
, and the volum e o f the veneer 

### sla g laye r i s 1,50 0 cubi c yards

. Th e lan d i s vacant a t this time

. Par t o f thi s sit e i s locate d withi n Urba n Residentia l zonin g distric t establishe d b y th e Lak e Count y Boar d o f Count y Commissioner s (Lak e County

, 1997 ) an d th e remainin g portio n is locate d withi n th e Traditiona l 

### Residential/Commercia l

zonin g distric t establishe d b y th e Cit y o f Leadville

. Curren t lan d us e surroundin g th e sit e consist s o f bot h residentia l an d recreationa l use
. T h e Wester n Zin c Smelte r sit e is locate d i n th e wester n par t o f Leadville

, approximatel y 7 5 fee t 

### wes t o f McWeth y Drive an d approximatel y 10 0 fee t sout h o f th e Lak e Count y Fairgrounds

. Th e Wester n Zin c Smelte r bega n operation s i n 191 4 an d continue d operating unti l 1926

. Th e smelte r processe d zinc or e t o a zin c oxid e produc t fo r us e as pigment

. Material s identifie d in 199 2 (WCC

, 1992a ) includ e sla g piles
, sla g veneer , smelte r debris (includin g ol d foundatio n footprints a n d brick s possibl y used i n th e furnaces)
, an d solidifie d bag-house/flu e dust

. Th e Wester n Zin c Smelte r feature s ar e show n i n Figur e 6

. Th e volum e o f th e sla g pile s i s estimate d t o b e 

### approximatel y 23,00 0 cubic yards

. Th e volum e o f bag-house/flu e dus t an d smelte r debris ar e estimate d a t les s tha n 5 an d 60 0 cubi c yards
, respectively

. Th e lan d i s vacant a t thi s time

. Th e sit e i s locate d withi n a n Urba n Residentia l zonin g distric t establishe d b y th e Lak e Count y Boar d
o f Count y Commissioner s (Lak e County

, 1997)

. T h e Arkansa s Valle y Sout h Hillsid e Sla g Pil e i s locate d sout h o f U.S

. Highwa y 2 4 o n th e hillside 

### acros s fro m th e Arkansa s Valle y Smelte r sit e an d extend s approximatel y 2,00 0 feet
, roughl y parallelin g Californi a Gulc h an d U.S

. Highwa y 24

. Thi s slag pile is als o referre d t o i n th e Lea d Sla g Remedia l Investigatio n (RI ) repor t a s th e "Tramway " Sla g Pil e (MK

, 1992a)

. Th e histor y o f this sla g pile is unknown ; i t is possibl e tha t eithe r th e Arkansa s Valle y o r Grant/Unio n Smelter s supplie d th e sla g a t thi s site

. Usin g curren t aerial photograph s th e volum e i s estimate d t o b e approximatel y 16,00 0 cubi c yard s fro m th e tw o elongate d pile s o f slag

. Th e large r sla g pil e exist s as a wedge-shape d mound
, formin g wha t appear s t o hav e been a roadbe d u p t o 5 0 fee t wid e a t t h e base

. Th e smalle r sla g pil e extend s southeas t abou t 40 0 feet

. Th e sit e feature s o f th e 

### Arkansa s Valle y Sout h Hillsid e Sla g Pil e ar e shown i n Figur e 7

. Muc h o f th e sla g consist s o f air

cooled
, whol e "sla g buttons " measurin g u p t o thre e fee t across
. Ther e ar e n o smelte r remains , buildin g debris
, o r othe r wast e material s excep t slag

. Th e lan d a t thi s sit e i s vacant a t thi s time

. T h e sit e is locate d withi n th e Industria l an d Minin g zonin g distric t establishe d b y th e Lak e Count y Board o f Count y Commissioner s (Lak e County

, 1997)

. Lak e Count y i s relativel y smal l (38 0 squar e miles ) an d i s predominatel y rural
, wit h a 199 0 populatio n o f 6,00 7 (U.S

. Departmen t o f Commerce

, 1990)

. Abou t hal f o f thi s populatio n reside s withi n th e Cit y o f Leadville

. Th e populatio n o f Lak e Count y ha s fluctuate d wit h th e minin g industry

. Th e populatio n increase d t o abou t 9,00 0 betwee n 1960 an d 198 1 an d the n decline d throughou t th e 1980s

. Abou t two-third s o f th e lan d i n Lak e Count y i s federall y owne d an d i s 

### eithe r pa n o f Sa n Isabe l Nationa l Fores t o r manage d b y th e Burea u o f Lan d Management

. T h e climat e o f Lak e Count y is semi-arid continental
, characterize d b y long
, col d winter s an d short
, coo l summers
. Th e Cit y o f Leadville i s a t a n elevatio n near 10,00 0 fee t abov e mea n se a level

. Th e averag e annua l maximu m temperatur e i n th e Leadville area is 50. 5 degree s Fahrenheit

, DS- 2

### an d

the averag e annual minimum temperatur e i s 21. 9 degree s Fahrenheit

, wit h a n annua l mea n 

### temperatur e o f 37. 3 degree s Fahrenheit

. Averag e annual precipitatio n i s approximatel y 1 6 inches
, whic h represent s 5 9 year s o f recor d fro m th e Colorad o Climat e Cente r (1997)

. Prevailin g wind s in th e Leadvill e are a ar e largel y fro m th e west-northwes t an d t o a lesse r extent fro m th e northeas t 

### (ESI

, 1986)
, wit h wind s typicall y rangin g fro m 0 t o 2 0 mile s pe r hour (WCC

, 1992b).

DS- 3

### 2 . 0

OPERABL E UNI T HISTOR Y AN D ENFORCEMEN T ACTIVITIE S T h e Californi a Gulc h Superfun d Sit e i s locate d i n th e highl y mineralize d Colorad o Minera l Bel t o f t h e Rock y Mountains

. Mining
, minera l processing , an d smeltin g activitie s hav e produce d gold
, 

### silver
, lead
, an d zinc fo r mor e tha n 13 0 year s in th e Leadvill e area
. Th e Leadvill e Histori c Minin g Distric t include s a n extensiv e networ k o f undergroun d mine working s i n a mineralize d are a o f 

### approximatel y eigh t squar e mile s locate d around Breece Hill

. Minin g in th e Distric t bega n in 1860 , when place r gol d wa s discovere d i n Californi a Gulch

. A s th e place r deposit s wer e 

### exhausted
, undergroun d working s became th e principa l metho d fo r removin g gold
, silver
, lead
, an d zinc ore
. A s thes e mine s wer e developed
, wast e roc k wa s excavate d alon g wit h th e or e an d place d nea r the mine entrances

. Man y mines wer e operate d i n the are a a s evidence d b y mor e tha n 

### 2,00 0 min e wast e roc k pile s identifie d a t th e Californi a Gulc h Superfiin d Site

. Mine d or e was 

### transporte d t o nearb y mill s where i t was crushe d an d separate d int o metallic'concentrate s

an d wast e (mil l tailing)

. Th e hig h grad e ore s an d mil l concentrate s wer e refine d an d processe d a t 

### smelters

. Sla g an d othe r wast e product s wer e produce d fro m th e smelters

. Approximatel y 1 7 smelte r facilitie s ar e reporte d t o have once operate d withi n th e Site ! Mos t operation s cease d b y about 1900 , althoug h som e facilitie s onc e continue d t o operat e int o th e 

### 1960s

. A t present , nearl y al l th e mine s withi n th e sit e boundarie s ar e inactive

. Al l o f th e mill s an d smelter s tha t operate d o n th e Sit e ar e inactiv e and/o r demolished

. D u e t o histori c mining , milling
, an d smeltin g operations , th e Sit e contain s man y tailing
, impoundments
, fluvia l deposits
, sla g piles
, wast e roc k piles
, an d mine wate r drainag e tunnels

. Sla g o n th e Sit e i s th e wast e byproduc t o f smeltin g an d result s fro m th e processin g o f or e in hig h 

### temperatur e furnaces

. 

### T h e Californi a Gulc h Sit e wa s place d o n th e Nationa l Prioritie s Lis t (NPL ) i n 198 3 unde r th e authorit y o f th e Comprehensiv e Environmenta l Response

, Compensation

, an d Liabilit y Ac t 

### (CERCLA ) o f 1980

. Th e Sit e wa s place d o n th e NP L becaus e o f concerns about th e impac t o f mine drainag e o n surfac e water s in th e Californi a Gulc h an d th e impac t o f heav y metal s loading in th e Arkansa s River

. I n Septembe r 1990, EP A an d th e PRP s entere d int o a n Administrativ e Orde r o n Consen t (AOC ) 

### f o r th e performanc e o f soil s samplin g an d air monitoring

. EP A issue d a Unilatera l Administrativ e Orde r (UAO ) in 199 1 tha t require d ASARCO t o conduc t studie s an d complet e RIs

. : Severa l subsequen t investigation s hav e been conducte d withi n th e Californi a Gulc h Superfun d Sit e tha t hav e addresse d th e smelter/slag/mil l site s (i.e.
, OU5)

. A Smelte r Sit e Reconnaissanc e 

### (WCC

, 1992a ) wa s conducte d in 199 1 a s par t o f th e Smelte r R J an d a Sla g Pil e Reconnaissanc e a s par t o f th e Sla g Pil e RIs

.' I I n 199 1 throug h 1992 , a Smelte r R I wa s conducte d an d primaril y focuse d o n smelte r impacte d 

### soil s bu t als o include d sampling o f discret e location s wher e smelte r ba g houses
, dus t chambers
, o r roastin g furnace s may hav e been locate d (Walsh
, 1993)

. This stud y wa s initiate d b y ASARC O

a n d include d th e Elgi n Smelter

, Grant/Unio n Smelter

, Wester n Zin c Smelter

, an d Arkansa s Valley

- Smelte r sites

. DS- 4A surfac e wate r R I (Surfac e Wate r RI ) o f th e Californi a Gulc h Sit e wa s conducte d i n 199 1 an d 1992

. Th e fina l Surfac e Wate r R I repor t wa s issue d in 199 6 describin g th e result s o f th e surfac e 

### wate r investigatio n (Golder

, 1996a)

. Th e stud y include d surfac e wate r an d sedimen t sampling i n t h e Arkansa s River an d it s tributaries
, including Californi a Gulch

. A groundwate r R I (Hydrogeologi c RI ) a t th e Californi a Gulc h Sit e was conducte d in 199 1 

### throug h 1992

. Th e stud y include d installatio n o f monitorin g well s an d piezometers , wate r leve l measurements , an d groundwate r sampling an d analysis

. Th e fina l Hydrogeologi c R I Repor t describin g th e result s o f th e investigatio n wa s issue d i n 199 6 (Golder

, 1996b)

. Objective s o f th e 

### stud y wer e t o investigat e groundwate r qualit y an d flo w directions
, evaluat e potentia l impact s t o surfac e wate r receptors , an d characteriz e backgroun d groundwate r quality

. Denve r an d Rio Grand e Wester n Railroad

, anothe r PR P a t th e Site

, undertoo k RJ s o f seven majo r lea d sla g pile s (MK

, 1992a ) includin g th e Elgi n Smelte r an d Grant/Unio n Smelte r site s an d on e zin c sla g pile (MK

, 1992b)
, Wester n Zin c sla g pile
, withi n th e Californi a Gulc h Site

. Th e Zin c Sla g R I wa s performe d concurren t wit h th e Lea d Sla g Pil e RI

. Investigatio n activitie s durin g 

### thes e tw o RI s focuse d mainl y o n th e slag materia l tha t ma y hav e th e potentia l t o leac h metal s t o t h e environment

. 

### I n 1993 , th e EP A conducte d a Screenin g Feasibilit y Stud y (SFS ) (EPA

, 1993 ) t o initiat e th e overal l CERCL A feasibilit y stud y (FS ) proces s a t th e Californi a Gulc h Site

. Th e purpos e o f th e 

### S F S wa s t o develo p genera l respons e action s an d identif y a n appropriate rang e o f alternative s applicable t o th e variou s contaminan t sources t o b e considere d durin g feasibilit y studie s fo r th e Californi a Gulc h Site

. Remedia l alternative s retaine d i n th e SF S fo r slag an d non-residentia l area soil s i n OU 5 fo r th e EGW A site s wer e furthe r evaluate d an d screene d durin g th e focuse d feasibilit y stud y (FFS ) (MFG

, 1999)

. ASARC O entere d int o a Consen t Decre e (CD ) (USDC

, 1994 ) wit h th e Unite d States

, th e Stat e o f Colorad o (State)

, an d othe r PRP s a t th e Californi a Gulc h Sit e o n May 4 , 199 4 I n th e CD

, ASARC O agree d t o perfor m certain remediatio n wor k i n thre e operabl e unit s (OU5

, OU7

, an d 

### OU9)

. Th e Wor k Are a Managemen t Plan

, include d a s Appendi x B t o th e C D (USDC

, 1994)
, 

### define s th e scop e o f wor k t o b e performe d b y ASARCO

. I n Februar y o f 1999 , ASARC O submitte d th e Focused Feasibility Study fo r Operable Unit 5 EGWA Sites (MFG

, 1999)
, accordin g t o th e term s o f th e CD

. Th e FF S provide d a detaile d analysi s o f th e tw o retaine d alternative s fro m th e SF S a s applie d t o slag an d fou r alternative s fro m t h e SF S fo r non-residentia l are a soils

. Non-residentia l are a soil s ar e define d a s soi l i n area s currentl y zone d agricultural/forest
,

recreational
, highway/business
,

retai l core , commercial
, an d industria l mining

. Fo r th e purpos e o f th e FF S an d ROD

, non-residentia l are a soil s wer e evaluate d instea d o f bot h non-residentia l an d residentia l area soil s becaus e n o residence s ar e locate d withi n 

### t h e OU 5 EGW A sites

. However
, it i s reasonabl y anticipate d th e some o f th e site s ma y b e occupie d a s residentia l lan d us e base d o n th e curren t residentia l zoning

. Institutiona l control s wil l 

### ensur e futur e protectiveness

. A Propose d Pla n describin g th e EPA' s preferre d alternativ e wa s issue d o n Jul y 21 , 2000

. Th e preferre d alternativ e wa s .Alternativ e 2

. Institutiona l Controls

. DS- 5

### 3 . 0

HIGHLIGHT

S O F COMMUNIT Y PARTICIPATIO N Publi c participatio n is require d b y CERCL A Section s 11 3 an d 117

. Thes e section s requir e tha t 

### befor e adoptio n o f an y pla n fo r remedia l actio n t o be undertake n b y EPA

, th e State

, o r a n individua l (e.g.
, PRP)

, th e lea d agenc y shall : 1

. Publis h a - notic e an d mak e th e Propose d Pla n availabl e t o th e public
, an d 2

. Provid e a reasonabl e opportunit y fo r submissio n o f writte n an d oral comment s an d
a n opportunit y fo r a publi c meetin g a t o r nea r th e sit e regardin g th e Propose d Pla n 

### a n d any propose d finding s relating t o cleanu p standards

. Th e lea d agenc y shal l keep-a

. transcrip t o f th e meetin g an d mak e suc h transcrip t availabl e t o th e public

. T h e notic e an d analysis publishe d unde r ite m # 1 above shal l includ e sufficien t 

### informatio n t o provid e a reasonabl e explanatio n o f th e Propose d Pla n an d alternativ e proposal s considered

. Additionally
, notic e o f th e fina l remedia l actio n pla n se t fort h in th e RO D mus t b e published
, an d 

### t h e pla n mus t b e mad e availabl e t o th e publi c befor e commencin g an y remedia l action

. Suc h a fina l pla n mus t be accompanie d b y a discussio n o f an y significan t change s t o th e preferre d remed y presente d in th e Propose d Pla n alon g wit h th e reasons fo r th e changes

. A respons e 

### (Responsivenes s Summary ) t o eac h o f th e significan t comments , criticisms , an d ne w dat a submitte d in writte n o r oral presentation s durin g th e publi c comment perio d mus t be include d wit h th e ROD

. 

### E P A ha s conducte d th e require d communit y participatio n activitie s throug h th e presentatio n o f t h e RI/F S an d th e Propose d Plan

, a 30-da y publi c comment period
, a forma l publi c hearing
, an d t h e presentatio n o f th e Selecte d Remed y in this ROD

. Writte n comment s wer e receive d fro m 

### CDPHE

. EPA' s respons e t o writte n comment s receive d durin g th e publi c commen t perio d i s include d in th e Responsivenes s Summary

, whic h i s Appendi x A

. T h e Propose d Pla n fo r OLJ 5 EGW A site s wa s release d fo r publi c comment o n Jul y 27, 2000

. Th e 

### RI/F S an d th e Propose d Pla n wer e mad e availabl e t o th e publi c in th e Administrativ e Recor d locate d a t th e EP A Superfun d Record s Cente r in Denve r an d th e Lak e Count y Publi c Library in 

### Leadville

. A forma l publi c commen t perio d wa s designate d fro m Jul y 2 7 through Augus t 28 , 2000

. ; 

### O n Augus t 1 , 2000 , th e EP A hoste d a publi c meetin g t o presen t th e Propose d Pla n fo r EGW A Site s OU 5 o f th e Californi a Gulc h Superfun d Site

. Th e meetin g wa s hel d a t 7:0 0 p.m

. i n th e Minin g Hal l o f Fam e an d Museu m i n Leadville

, Colorado

. Representative s

fro m ASARC O 

### presente d th e Propose d Plan

, whic h discusse d th e followin g fou r alternatives : Alternativ e 1 : N o Actio n Alternativ e 2 : Institutiona l Control s Alternativ e 3 : N o Actio n fo r Slag

, Containmen t fo r Non-Residentia l .Are a Soil s a n d Residentia l Are a Soils

, an d Institutiona l Control s DS- 6Alternativ e

4 : N o Actio n fo r Slag

, Removal/Transport/Disposa l

o f Non

- 

### Residentia l Are a Soil s an d Residentia l Are a Soil s t o a n On-Site Repository

, an d 

### Institutiona l Control s 

### Institutiona l Controls

, Alternativ e 2 , wa s presente d a s EPA' s preferre d alternative

. A portio n o f t h e publi c meetin g wa s dedicate d t o answerin g question s an d acceptin g forma l ora l comment s 

### fro m th e public

. Communit y acceptanc e o f th e Selecte d Remed y is discusse d i n Sectio n 10.0, | Summar y o f Comparativ e Analysi s o f Alternatives
, o f this Decisio n Summary

. j

DS- 74 . 0

SCOP E AN D ROL E O F OPERABL E UNI T T h e Californi a Gulc h Superfun d Sit e cover s a wid e are a (Figur e 2)

. A s wit h man y Super-fun d 

### sites , th e problem s a t th e Californi a Gulc h Superfun d Sit e ar e complex

. A s a result
, EP A establishe d th e followin g OU s fo r th e divisio n o f liabilit y i n geographically

- o r media-base d area s within th e Site

. Th e OU s ar e designate d as : O U 1 Ya k Tunnel/Wate r Treatmen t Plan t 

### O U 2 Malta Gulc h Fluvia l Tailing/Leadville Corporatio n Mill/Malta Gulc h Tailing Impoundmen t 

### O U 3 D&RG W Sla g Piles/Railroa d Easement/Railroa d

Yar d an d Stockpile d Fin e Sla g O U 4 Uppe r Californi a Gulc h O U S ASARC O Smelter/Slag/Mil l Site s O U 6 Star r Ditch/Penros e Dump/Stra y Hors e Gulch/Evan s Gulc h O U 7 Apach e Tailin g Impoundment s O U S Lowe r Californi a Gulc h 

### O U 9 Residentia l Populate d Areas OU1 0 Orego n Gulc h OU1 1 Arkansa s Rive r Valle y Floodplai n 

### OU1 2 Site-Wid e Wate r Qualit y Remedia l action s undertake n within OU S EGW A site s ar e intende d t o b e consisten t wit h th e remedia l actio n objective s an d goal s identifie d fo r th e entir e Californi a Gulc h Superfun d Sit e an d othe r O U investigations

. Thi s decisio n documen t make s n o determinatio n o n whethe r surfac e wate r o r groundwate r withi n O U S EGW A site s requires remediation

. Pursuan t t o th e Augus t 26 , 1994 , C D a t thi s Site

, 

### (USDC

, 1994 ) it wa s agree d tha t th e decisio n o n remediatio n o f Site-wid e Surfac e Wate r an d Groundwate r (OU12) woul d b e mad e onl y afte r remedie s fo r sourc e remediatio n wer e selecte d
a n d implemente d a t eac h OU

. A s a result
, specifi c wate r qualit y goal s fo r Surfac e Wate r an d Groundwate r hav e not been establishe d at thi s time

.

DS- 85 . 0

SUMMAR Y OF SIT E CHARACTERISTIC

S 

### Numerou s investigation s have been conducte d a t th e Californi a Gulc h Superiun d Site'fo r th e purpos e of : (1 ) characterizin g site-wid e environmenta l conditions ; (2 ) identifyin g an d 

### characterizin g historic smelte r activitie s an d associate d wast e materials
, an d (3 ) characterizin g lea d an d zinc slag

. Sit e characterizatio n t o assess th e genera l condition s o f th e OU 5 EGW A site s an d t o evaluat e th e natur e an d exten t o f contaminatio n withi n thes e site s i s base d o n informatio n presente d i n th e FF S (MFG

, 1999)
, Lea d Sla g R I (MK

, 1992a)
, Zin c Sla g R I (MX

, 1992b)
, Soils Investigatio n (CDM

, 1994)
, Smelte r R I (Walsh
, 1993 ) an d Smelte r Supplementa l R I (WESTEC

, 

### 1997a)

. 5 . 1 PHYSICA L CHARACTERISTIC

S 

### T h e physica l characteristic s o f eac h o f th e fou r site s ar e discusse d below

. 5.1. 1 Summar y o f Soi l an d Smelte r Waste Materia l Samplin g - Elgi n Smelte r Soi l an d smelte r wast e materia l sample s wer e obtaine d a t th e Elgi n Smelte r site

. Sampl e LES101

, 

### a composit e sla g sample
, wa s obtaine d durin g th e Lea d Sla g R J (MK

, 1992a)

. Sample s collecte d durin g th e Smelte r R I include d on e discret e sample
, S09-003

, an d thre e primar y gri d (PG ) samples
, PG-620

, PG-621

, an d PG-64 3 (Walsh
, 1993)

. Thre e samples
, SEL01

, SEL02

, SELr03

, 

### wer e collecte d durin g th e Smelte r Supplementa l R I (WESTEC

, 1997a)

. Analytica l result s an d th e 

### location s fo r thes e sample s ar e shown o n Figur e 8

. T h e averag e concentration s o f lea d an d arseni c i n soi l fro m th e 0 t o 6 inch dept h interva l a t th e Elgi n Smelte r sit e ar e 2,79 0 an d 11 3 mg/kg
, respectively

. 5.1. 2 Summar y o f Soi l an d Smelte r Waste Materia l Samplin g - Grant/Unio n Smelte r Soi l an d smelte r wast e materia l sample s wer e obtaine d a t th e Grant/Unio n Smelte r site

. On e 

### sample
, GGS101

, wa s obtaine d durin g th e Lea d Sla g R I (MK

, 1992a)

. Fiv e sample s obtaine d durin g th e Smelte r R I includ e PG-215

, PG-216

, PG-232

, PG-252

, an d PG-027 5 (Walsh
, 1993)

. 

### Sampl e SGU0 1 wa s collecte d durin g th e Smelte r Supplementa l R I (WESTEC

, 1997a)

. Analytica l result s an d th e location s fo r thes e sample s ar e shown o n Figur e 9

. T h e averag e concentration s o f lea d an d arseni c in soil fro m th e 0 t o 6 inc h dept h interva l a t th e Grant/Unio n Smelte r sit e ar e 2,28 6 an d 5 0 mg/kg
, respectively

. 5.1. 3 Summar y o f Soi l an d Smelte r Waste Materia l Samplin g - Wester n Zin c 

### Soi l an d smelte r wast e materia l sample s were obtaine d a t th e Wester n Zin c Smelte r site

. Fou r 

### samples
, HSS101

, HSS102

, HSS103

, an d HSS104

, wer e obtaine d durin g th e Zin c Sla g R I (MF

, 1992b)

. A s reporte d i n th e Smelte r RI

, fou r primary gri d sample s (PG-208

, PG-222

, PG-223

, a n d PG-238 ) an d tw o discret e sample s (S22-00 1 an d S22-002 ) wer e obtaine d (Walsh
, 1993)

. DS- 9

### O n e sample
, SWZ01

, wa s obtaine d fo r suspecte d bag-house/flu e dus t durin g th e Supplementa l Smelte r R I (WESTEC

, 1997a)

. Analytica l result s an d th e location s fo r al l th e sample s ar e show n o n Figur e 1 0 I n addition
, Toxicit y Characteristi c Leachin g Procedur e (TCLP ) analysi s o f sampl e SWZ0 1 (suspecte d baa

house/flu e dus t material ) show s tha t th e metal s in this materia l ar e no t readil y leachabl e an d th e materia l i s relativel y inert chemically

. Concentration s o f arsenic , cadmiu m an d lea d in th e TCL P 

### effluen t wer e al l belo w th e respectiv e limit s o f detectio n fo r thes e metals

. Zin c wa s detecte d i n t h e TCL P effluen t a t a concentratio n o f 0.0 1 milligram s pe r lite r (mg/L)

. T h e averag e concentration s o f arsenic an d lea d in soil fro m th e 0 t o 6 inch dept h interva l a t th e 

### Wester n Zin c Smelte r sit e ar e 10 0 an d 80 3 mg/kg
, respectively

. 5.1. 4 Summar y o f Samplin g - Arkansa s Valle y South Hillsid e Sla g Pil e 

### Ther e ha s been n o sampling o r analysi s o f sla g materia l a t th e Arkansa s Valle y Sout h Hillsid e Sla g Pil e site

. A s par t o f th e site-wid e Soil s Investigatio n (CDM

, 1994 ) an d Smelte r R I (Walsh
, 1993)
, 

### soil surroundin g th e sit e wa s sample d an d analyzed

. Analytica l result s an d th e location s fo r thes e sampling efforts ar e show n o n Figur e 11

. 

### Sample s obtaine d a s par t o f th e site-wid e Soils Investigatio n include d PG-046

, PG-065

, an d PG

076

. Sample s obtaine d a s par t o f th e Smelte r R I include d SME-14 7 an d SME-152

. Th e result s 

### indicate d tha t soil s a t th e sit e ma y hav e been impacte d b y emission s fro m th e Arkansa s Valle y Smelter

, rathe r tha n b y metal s release d fro m th e Arkansa s Valle y Sout h Hillsid e Slag Pile (CDM

, 1994)

. T h e averag e arseni c an d lea d concentration s i n soil fo r th e Arkansa s Valle y Sout h Hillsid e Sla g Pil e sit e ar e 14 0 an d 1,16 1 mg/kg
, respectively

. 5 . 2 GROUND W ATE R AN D SURFAC E WATE R QUALIT Y Syntheti c Precipitatio n Leachin g Procedur e (SPLP

, EP A Metho d 1 3 12 ) an d colum n leachin g test s conducte d o n sample s o f lea d an d zinc sla g indicat e tha t meta l concentration s in sla g leachat e i s no t a significan t contaminan t migratio n pathway (MK

, 1992a an d 1992b)

. 5.2. 1 Elgi n Smelte r Result s o f th e Surfac e Wate r R I (Golder

, 1996b ) indicat e tha t surfac e wate r qualit y i n Bi g Evan s Gulc h is no t bein g adversel y affecte d b y wast e material s a t th e Elgi n Smelte r site

. Surfac e wate r samplin g statio n EG- 1 is locate d o n Bi g Evans Gulc h upstrea m o f th e confluenc e wit h Littl e Evans Gulc h an d approximatel y 2,50 0 fee t upstrea m fro m th e forme r Elgi n Smelte r site

. Surfac e wate r sampling statio n EG- 2 i s locate d approximatel y 1,00 0 fee t downstrea m o f th e Elgi n Smelte r site

. Result s o f th e Surfac e Wate r R I fo r th e fou r EGW A samplin g station s ar e presente d i n Tabl e 1

. Wate r chemistry dat a fo r upgradien t (EG-1 ) an d downgradien t (EG-2 ) station s ar e virtuall y identica l indicatin a tha t th e smelte r material s wer e no t a sianifican t sourc e o f metal s t o DS-I OEvans

Gulc h durin g thi s sampling period

. Any impac t t o Surfac e Wate r an d Groundwate r wil l b e 

### addresse d in OU12

. 5.2. 2 Grant/Unio n Smelte r Ther e ar e no surfac e wate r feature s at the sit e and no obvious runof f channel s o r erosio n feature s tha t woul d indicat e a potentia l migratio n pathway t o Georgi a Gulc h o r Californi a Gulch

. Samplin g conducte d a t Georgi a Gulc h (surfac e wate r monitorin g statio n GG-1 ) indicate s tha t 

### wate r qualit y in this drainag e doe s no t appea r t o be adversel y affecte d b y sla g o r othe r material s a t t h e Grant/Unio n Smelte r sit e (Golder

, 1996b)

. Surfac e wate r monitorin g statio n GG- 1 i s locate d immediatel y wes t o f th e forme r Grant/Unio n Smelte r site , jus t upstrea m fro m th e confluenc e wit h Californi a Gulch

. Tabl e 1 does sho w impac t t o surfac e water , however
, th e impac t does no t 

### com e fro m th e Grant/Unio n Smelte r site

. An y impac t t o Surfac e Wate r an d Groundwate r wil l b e addresse d inOU12

. 5.2. 3 Wester n Zin c Smelte r Ther e ar e tw o groundwate r monitorin g point s i n th e vicinit y o f th e Wester n Zin c Smelte r site

. Well BMW- 1 i s screene d in bedroc k a t a dept h o f approximatel y 1,22 9 t o 1,24 4 fee t belo w 

### groun d surface

. Piezomete r PZ- 4 i s screene d i n alluviu m a t a dept h o f approximatel y 12 5 t o 13 7 fee t belo w groun d surface

. Groundwate r qualit y in thes e tw o well s i s consisten t wit h othe r backgroun d .monitorin g wells
, which suggest s tha t smelte r wast e material s hav e no t adversel y 

### affecte d groundwate r a t thes e depths

. Thi s is consisten t wit h th e SPL P an d colum n leachin g test s conducte d b y M K (1992b ) o n sample s o f zin c slag

. Tes t result s indicat e tha t meta l concentration s i n sla g leachat e d o no t creat e a significan t contaminan t migratio n pathway a t thi s site

. 

### T h e Surfac e Wate r R I (Golder

, 1996b ) did no t identif y an y surfac e wate r bodie s a t th e Wester n Zin c Smelte r sit e an d n o sampling was conducted

. Becaus e o f th e absenc e o f surfac e wate r features
, it i s no t expecte d tha t smelter-relate d material s a t this sit e coul d adversel y impac t surfac e 

### wate r qualit y in th e area
. An y impac t t o Surfac e Wate r an d Groundwate r wil l be addresse d in OU12

. : 5.2. 4 Arkansa s Valle y Sout h Hillsid e Sla g Pil e 

### T h e Surfac e Wate r R I (Golder

, 1996b ) did no t identif y an y surfac e wate r bodie s a t the

. Arkansa s Valle y Sout h Hillsid e Sla g Pil e sit e an d n o sampling wa s conducted

. Becaus e o f th e absenc e o f 

### surfac e wate r features
, wast e a t this sit e i s no t expecte d t o impac t surfac e wate r qualit y in th e area
. Ther e ar e n o groundwate r monitorin g well s in th e vicinit y o f th e site

. An y impac t t o 

### Surfac e Wate r an d Groundwate r wil l b e addresse d i n OU12

. Althoug h severa l erosio n feature s tha t have "cu t through " section s o f th e mai n sla g pile ar e evident
, a revie w o f aerial photograph s dating bac k t o 194 4 indicat e tha t transpor t o f slag doe s no t appea r t o b e a n ongoin g condition

.

DS-l l

### 5 . 3 HISTORI

C AN D CULTURA L RESOURCE S T h e cultura l resource s o f OU 5 wer e surveye d i n Augus t an d Septembe r 199 5 fo r Elgi n Smelte r 

### sit e an d Grant/Unio n Smelte r sit e (FEC

, 1996a ) an d i n Jun e 199 6 fo r Wester n Zin c Smelte r sit e wit h th e result s include d a s a n addendu m (FEC

, 1996b)

. Th e Arkansa s Valle y South Hillsid e Sla g Pil e was no t surveye d o r evaluated ; however
, sinc e thi s sit e consist s solel y o f slag piles
, it i s ver y unlikel y that th e sit e contains an y feature s o f historica l o r cultura l significance

. Th e Elgi n Smelte r 

### (5LK893)

, Grant/Unio n Smelte r (5LK894)

, an d Wester n Zin c Smelte r (5LK924 ) site s wer e 

### recommende d a s no t bein g eligibl e fo r Nationa l Registe r o f Histori c Place s (NRHP ) an d ar e no t contributin g feature s t o th e Leadvill e Histori c Minin g Distric t unde r NRH P criteria

.

DS-1 26 . 0

CURREN T AN D POTENTIA L FUTUR E LAN D US E 

### Lan d surroundin g an d withi n th e Californi a Gulc h Superfun d Sit e is predominatel y dedicate d t o mining , commercial/industrial

, an d residentia l uses
. Th e OU 5 EGW A site s ar e locate d withi n area s zone d residential
, commercial
, an d industrial

. Th e EGW A site s ar e currentl y vacant an d


### m a y have intermitten t recreationa l visitors

. Th e Grant/Unio n an d Wester n Zin c Smelte r site s ar e currentl y zone d residential

. I t i s reasonabl y anticipate d tha t thes e tw o site s ma y be used fo r residential

. Th e Elgi n Smelte r an d Arkansa s Valle y Sout h Hillsid e Sla g Pil e site s ar e currentl y zone d Business an d ar e no t likel y t o be re-zone d fo r residentia l use
. Potentia l futur e lan d us e i s reasonabl y anticipate d t o b e consisten t wit h th e loca l Busines s zoning

. T he effectivenes s o f th e "overla y district, " as wel l as land us e changes
, an d plans/proposal s fo r futur e lan d us e at eac h site , woul d b e monitore d an d evaluate d a s par t o f the five-yea r revie w process

.



## DS-I :7 . 0 SUMMAR Y OF SIT E RISK S 

### Baselin e ris k assessment s (RA ) characteriz e potentia l human healt h an d ecologica l risks a t a sit e base d o n current condition s (i.e.
, no actio n take n at the site)

. Remedia l actio n i s drive n b y the potentia l fo r human healt h o r ecologica l risk ; th e R A indicate s th e medi a an d exposur e pathway s t o be addressed

. Contaminants

, receptors , exposur e pathways
, an d baselin e risks a t OU 5 ar e 

### describe d below

. 7 . 1 HUMA N HEALT H RISK S T h e followin g human healt h RA s ar e pertinen t t o OU5 :
• Weston

. 1991

. Preliminary Huma n Healt h Baselin e Ris k Assessmen t fo r th e Californi a 

### Gulc h NP L Site

, Leadville

, Colorado

. Prepare d by Roy

. F

. Weston
, Inc

. fo r th e EPA

. December

. (Preliminar y RA)

. 

### • Weston

. 1996a

. Baselin e Huma n Healt h Ris k Assessmen t fo r th e Californi a Gulc h Superfun d Site

, Ris k t o Resident s fro m Lea d (Par t A)

. Prepare d by Roy

. F

. Weston
, Inc

. f o r th e EPA

. January

. • Weston

. 1996b

. Baselin e Huma n Healt h Ris k Assessmen t fo r th e Californi a Gulc h Superfun d Site

, Ris k t o Resident s fro m Contaminant s Othe r Tha n Lea d (Par t B)

. Prepare d b y Roy

. F

. Weston
, Inc

. fo r th e EPA

. January

. 

### • Weston

. 1995a

. Baselin e Huma n Healt h Ris k Assessmen t fo r th e Californi a Gulc h Superfun d Site

, Par t C : Evaluatio n o f Worke r Scenari o an d Evaluatio n o f Recreationa l 

### Scenarios

. Prepare d b y Roy

. F

. Weston
, Inc

. fo r th e EPA

. April

. T h e preliminar y R A (Weston
, 1991 ) evaluate d residentia l risks fro m exposur e t o contaminate d medi a (i.e.
, soil
, wast e rock
, tailing
, etc)

. Th e preliminar y R A als o evaluate d potentia l risks t o workers fro m futur e exposur e t o slag
, eve n thoug h th e exposur e pathway fo r lea d is incomplete

. 

### Sinc e th e completio n o f th e preliminar y RA

, several studie s wer e complete d tha t provide d additiona l dat a o n contaminan t concentration s an d o n human an d ecologica l exposures

. 

### Additionally
, Leadvill e official s an d busines s leader s expresse d concer n ove r possibl e risks an d liabilitie s associate d wit h commercia l an d recreationa l use s within th e Site

. Th e fina l baselin e R A (Weston
, 1995a , 1996a , an d 1996b ) wa s compose d o f th e followin g thre e parts :
• Pa n A Ris k t o Resident s fro m Lea d - evaluate d residentia l risk fro m exposur e t o 

### lead
, • Pa n B Ris k t o Resident s fro m Contaminant s Othe r tha n Lea d - evaluate d ris k t o resident s fro m exposur e t o contaminant s othe r tha n lead ; an d • Pa n C Evaluatio n o f Recreationa l Scenario s an d Evaluatio n o f Worke r Scenari o - develope d i n respons e t o communit y concerns , presente d risk-base d actio n level s t o determin e whethe r chemica l concentration s presente d a risk a t location s use d f o r commercial
, industrial
, o r recreationa l purposes

. DS-1 4T h e followin g section s summariz e th e result s o f thes e RAs

, including medi a an d contaminant s o f
concer n (COC)

, exposur e assessment , an d risk characterization
, a s they relat e t o OU5

. 7.1. 1 Medi a an d Contaminant s o f Concer n Potentia l medi a o f concer n i n OU 5 include s o f slag
, non-residentia l soils
, an d residentia l area soil s o f th e EGW A sites

. Result s o f th e preliminar y R A (Weston
, 1991 ) an d th e fina l R A (Weston
, 

### 1995a ) indicat e tha t human receptor s ar e expecte d t o hav e minima l exposur e t o slag

. Bot h th e preliminar y an d fina l R A indicat e tha t soi l i s th e mediu m o f concer n fo r human exposure

. Arseni c a n d lea d wer e used as indicato r contaminant s fo r ris k in th e fina l R A (Weston
, 1995a)

. Thes e chemical s wer e selecte d base d o n th e result s o f th e preliminar y R A (Weston
, 1991)
, whic h 

### indicat e tha t lea d an d arseni c ar e responsibl e fo r th e majorit y o f human healt h risk s a t th e Californi a Gulc h Superfun d Site

. 7.1. 2 Exposur e Assessmen t T h e EGW A site s ar e currentl y vacant

. Th e Elgi n Smelte r an d Arkansa s Valle y Sout h Hillsid e Sla g Pil e site s ar e currentl y zone d Busines s an d ar e no t likel y t o b e re-zone d fo r residentia l use
. Huma n receptor s o f concer n a t th e Elgi n Smelte r an d Arkansa s Valle y Sout h Hillsid e Sla g Pil e site s consis t o f commercia l an d industria l workers an d recreationa l visitors

. Th e Grant/Unio n an d Wester n Zin c Smelte r site s ar e currentl y zone d residential

. Huma n receptor s o f concer n a t th e Grant/Unio n an d Wester n Zin c Smelte r site s ar e recreationa l visitors , an d potentia l futur e residents

. T h e preliminar y R A identifie d potentia l primary sources o f metal s o f concern , th e mechanism s o f release s t o th e environment , an d receptor s i n a conceptua l sit e mode l as show n i n Figur e 12

. A 

### conceptua l sit e mode l wa s als o create d fo r residentia l us e (specifically
, exposur e t o children) an d i s shown in Figur e 13

. Th e fina l R A identifie d soil ingestio n a s th e exposur e pathwa y o f concer n f o r recreationa l visitors ; ingestio n o f soil an d dus t wa s identifie d a s th e exposur e pathwa y o f
concer n fo r commercial/industria l

workers ; an d ingestio n o f soil/dus t an d wast e pile s a s th e expose d pathwa y o f concer n fo r residents

. Exposur e t o othe r medi a (e.g.
, sla g piles ) an d 

### exposur e t o soil/dus t throug h othe r pathway s (e.g.
, dermal ) ar e considere d o f insignifican t
concer n fo r workers
, recreationa l user s an d resident s (Weston
, 1991)

. 7.1. 3 Risk Characterizatio n T h e fina l R A (Weston
, 1995a ) develope d risk-base d actio n level s fo r lea d an d othe r metals

. A s describe d above
, arsenic an d lea d ar e responsibl e fo r th e majorit y o f huma n healt h ris k a t th e Californi a Gulc h Superfun d Site

. Th e actio n level s develope d i n th e fina l R A represen t risk-base d chemica l concentrations , which ar e protectiv e o f human healt h an d ca n be compare d t o 

### contaminan t concentration s i n soil t o identif y area s o f potentia l concer n t o commercial/industria l workers
, recreationa l visitors , o r residents

. Th e actio n levels
, presente d a s a range , represen t th e l o w an d hig h value s calculate d base d o n th e uncertaintie s an d variation s o f th e exposur e parameters

.
DS-1 5F o r

commercial/industria l

exposure , th e soi l actio n leve l fo r lea d range d fro m a s lo w a s 2,20 0 

### mg/k g t o as hig h as 19,10 0 mg/kg
, whic h i s base d o n th e widel y varyin g exposur e parameters , 

### wit h centra l tendency values in th e 6,10 0 t o 7,70 0 mg/kg range
. Soil actio n level s fo r arsenic base d o n commercial/industria l

exposur e range d fro m 33 0 t o 1,30 0 mg/kg
, whic h i s base d o n th e 

### widel y varyin g exposur e parameters , wit h centra l tendenc y value s in th e 61 0 t o 69 0 mg/kg range
. F o r recreationa l exposure , th e soi l actio n leve l fo r lea d range d fro m as lo w as 5,00 0 mg/k g t o as hig h a s 85,00 0 mg/kg
, depending o n th e inpu t parameters

. Th e lea d concentratio n fo r 

### recreationa l exposur e was 16,00 0 mg/kg
, which i s th e actio n leve l calculate d i n th e RA (Western
, 1995a)

. Fo r arsenic , soi l actio n level s fo r recreationa l exposur e range d fro m 1,40 0 t o 3,20 0 mg/k g base d o n carcinogeni c an d systemic effects
, respectively

. Th e most appropriate arsenic concentratio n fo r us e as a recreationa l actio n leve l was 1,40 0 mg/kg
, base d o n th e potentia l fo r carcinogeni c effects

. F o r residentia l exposure , th e soil actio n level s ar e 3,50 0 mg/kg for.lea d an d 12 0 t o 34 0 mg/k g fo r 

### arsenic

. Th e arseni c leve l i s presente d as a lo w an d high rang e becaus e o f a numbe r o f uncertai n parameter s (e.g.
, ingestio n rat e fo r soil
, ingestio n rat e fo r dust
, th e contributio n o f soil t o dust
, th e uptak e o f metal s int o vegetables
, an d th e ingestio n rat e o f home-grow n vegetables)

. 

### T h e actio n level s ar e summarize d below :



# co c Lea d Arsenic Soi l Actio n Levels

, mg/kg Residentia l 3,50 0 12 0 - 34 0 

### Commercial/Industria l

6,100-7,70 0 610-69 0 

### Recreationa l

16,00 0 1,400-3,20 0 

### Soi l samplin g dat a fo r th e EGW A site s ar e reporte d fo r several dept h interval s including 0 t o 1 inch
, 1 t o 2 inches
, 2 t o 6 inches
, an d 1 2 t o 1 8 inches

. Th e metal s concentration s fro m th e dept h 

### interval s les s tha n 6 inches an d th e weighte d averag e concentration s fo r th e 0 t o 6 inc h dept h 

### interva l wer e compare d t o th e establishe d actio n level s fo r variou s lan d us e scenarios

. A t eac h o f th e fou r OU 5 EGW A sites , th e averag e concentratio n o f lea d an d arseni c fo r al l sample s a t eac h sit e (in th e 0 t o 6 inc h dept h interval ) ar e belo w th e risk-base d actio n level s 

### establishe d b y th e EP A fo r residentia l us e scenario a t th e Californi a Gulc h Superfim d Site

. However
, metal s concentration s i n soi l a t severa l individua l sampl e location s excee d th e actio n level s associate d wit h thei r current zoning , as describe d below

. ] 

### A t th e Elgi n Smelte r sit e (currentl y zone d commercial/industrial

) concentration s o f lea d an d arsenic a t on e sampl e location
, S09-00 3 (i n th e 0 t o 6 inc h dept h interval ) i n a n area withi n th e 

### footprin t o f th e histori c sla g pile an d nea r th e strea m channe l in Bi g Evan s Gulc h have been 

### measure d above th e sit e actio n levels * establishe d fo r th e commercial/industria l

worke r an d recreationa l exposur e scenarios

. DS-1 6A t th e Grant/Unio n Smelte r sit e (currentl y zone d residential ) concentration s o f lea d a t tw o sampl e 

### location s - SGU0 1 an d PG-23 2 - (in th e 0 t o 6 inch dept h interval ) in a n are a near th e existing sla g pile an d withi n th e footprin t o f th e histori c slag pile hav e been measure d abov e th e risk-base d sit e actio n level s establishe d fo r residentia l us e scenarios

. A t th e Wester n Zin c Smelte r sit e (currentl y zone d residential ) an d th e Arkansa s Valle y Smelte r 

### Sout h Hillsid e Sla g Pil e sit e (currentl y zoned commercial/industrial)
,

measure d concentration s o f lea d an d arseni c a t al l sampl e location s (in th e 0 t o 6 inch dept h interval ) ar e belo w th e risk-base d actio n level s establishe d b y th e EP A fo r residentia l an d commercial/industria l

us e scenarios , respectively

. However
, on e sampl e (S22-001) a t th e Wester n Zin c sit e exhibit s arsenic 

### concentrations , in th e 0 t o 1 inc h dept h interval
, tha t exceed s th e residentia l actio n level

. Becaus e thes e site s ar e vacant an d th e averag e soil concentration s across eac h sit e ar e wel l belo w 

### t h e risk-base d sit e actio n level s fo r a recreationa l us e scenario , which i s consisten t wit h curren t uses , condition s a t thes e site s d o no t pos e current unacceptabl e risks

. On e sampl e locatio n a t th e Elgi n Smelte r sit e ha s been identifie d a s havin g lea d an d arsenic concentration s in soil tha t excee d 

### t h e actio n leve l fo r recreationa l use
. Th e Elgi n Smelte r sit e is privat e propert y an d wil l b e evaluate d in 200 1 a s par t o f th e five-yea r sit e review

. Unde r potentia l futur e us e scenarios , th e relativel y smal l area s o f soil wit h lea d o r arseni c concentration s exceedin g thei r risk-base d actio n level s ma y presen t a potentia l human healt h risk
, dependin g o n th e actua l developmen t o f th e sit e 7 . 2 ECOLOGICA

L RISK S Baselin e RA s characterizin g ecologica l risks a t OU 5 consis t of :
• Weston

. 1995 b Fina l Baselin e Aquati c Ecologica l Ris k Assessment
, Californi a Gulc h N P L Site

. (BARA)

. • Weston

. 1997

. Ecologica l Ris k Assessmen t fo r th e Terrestria l Ecosystem

, Californi a Gulc h NP L Site

. Leadville

, Colorado

. (ERA)

. T h e BARA (Weston
, 1995b ) characterize s th e impact s o f mine wast e contaminatio n o n th e aquati c ecosyste m o f th e Californi a Gulc h Superfun d Site

. Ther e ar e n o surfac e wate r bodie s a t OU5

, an d surfac e water run=of f i s minimal

. Th e BARA does no t evaluat e risk s associate d wit h OU5

. Based o n thi s information
, aquatic risks ar e no t discusse d furthe r in this document

. Potentia l risk s t o th e terrestria l ecosyste m fro m mine wast e contaminatio n ar e characterize d in th e E R A (Weston
, 1997)

. Th e ER A provide s a conceptua l sit e mode l fo r terrestria l receptor s a t th e Californi a Gulc h Superiun d Sit e an d is show n i n Figur e 14

. I n th e ERA

, th e potentia l fo r advers e effects wa s evaluate d on a station-by-statio n basi s and on an O U basis

. Result s o f th e ER A relating t o OU5

, includin g medi a an d contaminant s o f concern , exposur e 

### assessment , an d ris k characterization
, ar e summarize d below

.

DS-1 77.2. 1

Medi a an d Contaminant s o f Concer n 

### T h e primary COC s identifie d in th e ER A wer e arsenic , cadmium
, copper , lead
, an d zinc

. Metal s concentration s wer e measure d i n tailin g piles
, min e wast e piles
, sla g piles
, surfac e soils
, surfac e 

### waters , an d fluvia l sediments

. Thes e medi a wer e considere d likel y pathway s o f exposur e t o biologica l receptor s that woul d o r coul d occur in th e uplan d and/o r th e wetlan d area s presen t in t h e Leadvill e area
. O U 5 was subdivide d int o fiv e subunit s ( A throug h E ) in th e ER A as follows : Arkansa s Valle y Smelter/Colorado Zinc-Lea d Mil l (OU5A)

, Arkansa s Valle y Sout h Hillsid e Slag Pil e (OU5B)

, Wester n Zin c Smelte r (OU5C)

, Grant/Unio n Smelte r (OU5D)

, an d th e Elgi n Smelte r (OU5E)

. 

### Risks t o ecologica l receptor s wer e calculate d fro m exposur e t o metal s in sla g an d soil in th e ERA

. 7.2. 2 Exposur e Assessmen t 

### Uplan d specie s include d mountai n bluebird
, leas t chipmunk
, blu e grouse , America n kestrel
, an d soi l fauna

. Wetlan d specie s include d re d winge d blackbird
, long-taile d vole
, belte d kingfisher
, an d spotte d sandpiper

. Specie s evaluate d tha t woul d b e potentia l receptor s i n bot h habitat s include d 

### bal d eagles
, mul e deer
, red-taile d hawk
, an d plants

. T h e exposur e pathway s evaluate d in th e ER A consiste d o f direc t exposur e t o contaminate d media
, incidenta l ingestio n o f contaminate d media
, an d indirec t exposur e throug h th e foo d chain

. 

### Contaminan t intake s fo r th e receptor s evaluate d wer e base d o n exposur e assumption s suc h as foo d ingestio n rate s an d bod y weight

. 

### T h e ER A used th e 9 5 percen t uppe r confidenc e limit o f th e arithmeti c mea n (UCL ) o f contaminan t concentration s in medi a t o evaluat e exposur e an d risk s fo r eac h OU

. I f th e maximu m 

### contaminan t concentratio n was les s tha n th e 9 5 percen t UCL

, th e maximum was used as th e exposur e poin t concentration

. 7.2. 3 Risk Characterizatio n T h e ER A reviewe d lexicologica l literatur e t o deriv e acceptabl e contaminan t intak e value s fo r 

### bird s an d mammals

. Resultin g benchmar k values
, referre d t o a s Toxicit y Benchmar k Value s (TBV)

, wer e compare d t o calculate d contaminan t intake s fo r ecologica l receptors

. T o estimat e risks
, th e ER A divide d estimate d intak e b y th e TB V t o deriv e a hazar d quotien t (HQ)

. 

### Contaminan t intake s greate r tha n TBV s (H Q greate r tha n 1 ) indicate d th e potentia l fo r toxicit y t o t h e receptor

. Result s o f th e ER A indicate d tha t terrestria l receptor s in OU 5 coul d have 

### contaminan t intak e greate r tha n TBVs

. Soil s withi n th e OU 5 EGW A site s may contribut e t o potentia l risk s t o terrestria l receptor s (e.g.
, th e mountai n bluebird)

. However
, risk s t o terrestria l receptor s fro m exposur e t o metal s in soil s a t th e OU 5 EGW A site s ar e considere d moderat e t o low
, an d remediatio n o f sourc e are a across th e Californi a Gulc h Superfun d Sit e wil l reduc e 

### exposur e t o terrestria l receptors

.

DS-1 S7 . 3 SUMMAR Y

O F RISKS/BASI S O F ACTION T h e respons e actio n selecte d i n this ROD fo r OU 5 EGW A is warrante d t o protec t th e publi c 

### healt h o r welfar e o r th e environmen t fro m actua l o r threatene d release s o f pollutant s o r contaminant s tha t ma y presen t a n imminent an d substantia l endangermen t fo r potentia l futur e us e o f th e sites

. Becaus e th e OU 5 EGW A site s ar e vacan t an d th e averag e soil concentration s across 

### eac h sit e ar e wel l belo w th e risk-base d sit e actio n level s fo r a recreationa l us e scenario , which i s consisten t wit h current uses , condition s a t thes e site s d o no t pos e current unacceptabl e risks

. On e sampl e locatio n a t th e Elgi n Smelte r sit e ha s been identifie d a s havin g lea d an d arsenic concentration s i n soi l tha t excee d th e actio n leve l fo r recreationa l use
. Th e Elgi n Smelte r sit e is privat e propert y an d wil l be evaluate d in 200 1 as pa n o f th e five-yea r sit e revie w Unde r potentia l futur e us e scenarios , th e relativel y smal l area s o f soil wit h lea d o r arsenic concentration s exceedin g thei r risk-base d actio n level s ma y presen t a potentia l human healt h risk
, dependin g o n 

### t h e actua l developmen t o f th e site

.

DS-1 9

### 8 . 0

REMEDIA L ACTIO N OBJECTIVE S 

### Thi s ROD wa s prepare d accordin g t o EP A guidanc e (EPA

, 1999)

. Th e remed y outline d i n thi s R OD i s intende d t o b e th e fina l remedia l actio n fo r OU 5 EGW A sites

. Th e primary objective s o f the remed y presente d i n this RO D are : Sla g Contro l

o f leachin g o f metal s o f concer n in concentration s tha t woul d hav e a n 

### advers e impac t o n soils
, surfac e water , o r groundwater ; Contro l airborn e transpor t o f contaminate d materials
, an d 

### Contro l erosio n o f contaminate d material s t o preven t depositio n int o loca l surfac e wate r courses
. Non-residentia l Are a Soils
• Contro l airborn e transpor t o f contaminate d materials ; 

### • Contro l erosio n o f contaminate d material s an d depositio n int o loca l wate r courses ; • Contro l leachin g an d migratio n o f metal s fro m soi l int o surfac e water ; 

### • Contro l leachin g an d migratio n o f metal s fro m soi l int o groundwater ; an d • Contro l contaminan t exposur e t o animal s an d aquatic life

. Residentia l Are a Soils

" • Preven t direc t exposur e o f th e populatio n t o elevate d concentration s o f contaminant s in th e surfac e soil

. T h e effectivenes s o f th e remedia l actio n alternative s wer e evaluate d wit h respec t t o thes e RAOs

. Remedia l action s undertake n withi n th e OU 5 EGW A site s ar e consisten t wit h th e remedia l actio n 

### objective s an d goal s identifie d fo r th e entir e Californi a Gulc h Superfun d Site

.

DS-2 09 . 0 DESCRIPTION

O F ALTERNATIVE

S 

### A wid e rang e o f cleanu p option s wer e considere d i n th e SF S (EPA

, 1993)

. Som e o f th e alternative s wer e eliminate d durin g preliminary screenin g becaus e the y woul d no t effectivel y addres s contamination , coul d no t be implemented
, o r woul d hav e ha d excessiv e costs

. Remedia l actio n alternative s fo r OU 5 fo r sla g an d non-residentia l are a soil s that wer e retaine d afte r screenin g alternative s fro m th e SF S wer e evaluate d i n th e FF S (MFG

, 1999)

. Al l o f th e alternative s wer e evaluate d usin g th e nine criteri a require d b y th e NC P as describe d in th e nex t 

### section , an d the n compare d wit h eac h o f th e othe r options

. A brie f descriptio n o f th e fou r clea n u p alternative s tha t wer e considere d fo r th e slag
, non residentia l are a soils
, an d residentia l are a soi l a t th e OU 5 EGW A site s as presente d in th e FF S (MFG

, 1999 ) an d th e Propose d Pla n (EPA

, 2000 ) is provide d below

. Alternativ e 1 : N o Actio n 

### Estimate d capita l an d operatin g cost : S O Implementatio n time : Immediat e 

### Thi s alternativ e leave s th e slag
, non-residentia l are a soils
, an d residentia l are a soil s in plac e wit h
n o remediation
, engineerin g o r institutiona l controls
, o r long-ter m maintenance

. Generally

, th e N o Actio n Alternativ e i s provide d fo r consideratio n a s a baselin e agains t whic h othe r technologie s 

### ca n be compare d in accordanc e wit h th e NCP

. N o Actio n i s no t protectiv e o f human healt h an d t h e environment

. A site-wid e surfac e an d groundwate r monitorin g progra m wil l be develope d


### onc e al l sourc e area s hav e been addressed

. ASARC O woul d conduc t an y require d monitorin g a t t h e sla g piles
, non-residentia l are a soils
, an d residentia l are a soils

. Thi s alternativ e is technicall y 

### feasibl e and cost-effectiv e since i t doe s not rel y on an y technolog y and ha s no cost

. Alternativ e 2 : Institutiona l Control s Estimate d capita l an d operatin g cost : $85,49 6 Implementatio n time : Immediat e 

### Institutiona l Control s consist s o f lega l restriction s applie d t o th e site s t o restric t accesso r activitie s an d include s measures t o provid e informatio n t o current and/o r futur e lan d owner s regardin g environmenta l condition s a t th e site , an d t o ensur e tha t i f thes e site s ar e develope d an y 

### necessar y specia l precaution s o r requirement s ar e followed

. Lak e Count y and/o r Cit y o f Leadvill e zonin g ordinance s woul d b e modifie d t o creat e a zonin g "overla y district " t o provid e alscreenin g 

### proces s t o identif y propertie s where specia l precaution s o r requirement s ma y be necessar y an d a mechanis m t o notif y owners and/o r developer s o f thes e requirements

. Th e requirement s woul d includ e condition s tha t mus t be me t t o ensur e protectivenes s an d ma y requir e additiona l sampling 

### o r respons e actions , t o b e conducte d o r funde d b y Asarco
, consisten t wit h th e developmen t plans

. A t th e Wester n Zin c Smelte r sit e (currentl y zone d Urba n Residential ) an d th e Arkansa s Valle y Hillsid e Sla g Pil e sit e (currentl y zone d Business)

, ther e i s n o evidenc e tha t soil contaminatio n exist s i n exceedanc e o f establishe d risk-base d actio n level s associate d wit h lan d us e scenario s DS-2 1

### consisten t

wit h th e current zonin g o f thes e tw o site

. A t th e Grant/Unio n (currentl y zone d Residential ) an d th e Elgi n (currentl y zone d Business ) Smelte r sites , soi l sampling dat a indicat e tha t whil e averag e concentration s o f metal s i n soi l (i n th e 0 t o 6 inc h dept h interval ) ar e belo w th e 

### establishe d risk-base d actio n level s fo r a residentia l lan d us e scenario , severa l smal l isolate d area s exhibit lea d and/o r arseni c concentration s tha t excee d th e risk-base d actio n level s fo r residentia l


### a n d commercial/industria l

us e scenarios , respectively

. A s state d previously
, al l o f th e OU 5 EGW A site s ar e vacant

. I f an d when futur e remediatio n occurs , ASARC O woul d conduc t o r fun d th e respons e activitie s consisten t wit h th e procedure s an d requirement s o f th e Lak e Count y Communit y Healt h Progra m 

### (LCCHP)

. Thes e activitie s woul d b e funde d by ASARC O separat e fro m th e LCCH P trus t fund

. A s th e EGW A site s ar e develope d o r zonin g change s ar e implemented
, th e area s wit h th e elevate d 

### metal s concentration s woul d b e addresse d unde r th e procedure s an d requirement s o f th e "overlay district. " Th e cost fo r potentia l futur e remediatio n wa s no t include d i n th e cost estimat e fo r Alternativ e 2 becaus e o f th e man y uncertaintie s an d unknown s associate d wit h potentia l futur e remediatio n effort

. Th e effectivenes s o f th e "overla y district/ a s wel l a s lan d us e changes
, an d plans/proposal s fo r futur e lan d us e a t eac h site , woul d be monitore d an d evaluate d as pa n o f th e 

### five-yea r revie w process

. Alternativ e 3 : N o Actio n fo r Slag ; Containmen t (Sourc e Surfac e Control ) fo r Non

- Residentia l Are a Soils an d Residentia l Are a Soils ; an d Institutiona l Control s 

### Estimate d capita l an d operatin g cost : 5151,71 4 Implementatio n time : Immediat e Thi s alternativ e entail s leavin g sla g i n place

. Soi l covers (fo r containment ) woul d b e place d over thos e area s tha t hav e elevate d lea d o r arsenic concentration s i n non-residentia l an d residentia l area soil s exceedin g th e risk-base d actio n levels

. Soil cover s woul d b e require d a t th e Elgi n an d Grant/Unio n Smelte r sites

. Fo r th e purpos e o f th e FF S an d ROD

, th e area s wher e soil woul d b e covere d ar e eac h 10 0 fee t lon g b y 10 0 fee t wide

. A simpl e cove r o f 1 2 inche s o f clea n borro w soil
, compacte d i n place
, woul d preven t exposur e t o th e soil b y reducin g th e potentia l fo r direc t contac t an d reduc e surfac e wate r contac t an d infiltration

. Revegetatio n o f th e ca p woul d reduc e erosio n du e t o surfac e wate r runoff
, preven t th e entrainmen t an d transpor t o f dust/particle s b y wind
, an d furthe r reduc e infiltration

. Institutiona l controls
, as describe d in Alternativ e 2 , woul d be implemente d in th e cove r area s t o prohibi t activitie s that migh t compromis e th e remedy

. Control s woul d include : (1 ) lan d us e restriction s an d requirement s fo r th e soil cove r area s an d (2 ) prohibitio n o f activitie s tha t woul d compromis e th e integrit y o f th e soil cover
. Th e effectivenes s o f th e "overla y district, " a s wel l a s lan d us e changes
, an d plans/proposals fo r futur e lan d us e a t eac h site , woul d b e monitore d an d evaluate d a s par t o f th e five-yea r revie w process

.

DS-2 2

### Alternativ e

4 : N o Actio n fo r Slag ; Removal/Transport/Disposa l

o f Non-Residentia l Are a Soil s an d Residentia l Are a Soil s t o a n On-Sit e Repository ; an d Institutiona l Control s 

### Estimate d capita l an d operatin g cost : 5181,66 8 Implementatio n time : Immediat e Thi s alternativ e entail s leavin g sla g in place

. Th e elevate d lea d o r arseni c concentration s in non 

### residentia l are a an d residentia l are a soil s tha t ma y pos e a potentia l human healt h concer n a t th e Elgi n an d Grant/Unio n Smelte r site s woul d b e remove d (t o a dept h o f 2 feet)
, transporte d an d dispose d a t a n on-sit e repository

. Th e removal actio n level s fo r th e Elgi n an d Grant/Unio n 

### Smelte r site s woul d be base d o n futur e lan d use, whic h woul d be residentia l an d commercial/industrial

, respectively

. Because o f th e volum e o f material s i s no t wel l quantified
, fo r t h e purpos e o f th e FF S an d ROD

, it i s estimate d that th e exten t o f excavation s a t th e Elgi n an d 

### Grant/Unio n Smelte r site s woul d eac h be 10 0 fee t lon g b y 10 0 fee t wid e b y 2 fee t dee p (i.e.
, approximatel y 74 0 cubi c yards)

. Disposa l woul d b e a t th e Arkansa s Valle y Smelte r site , Apach e Tailin g Impoundment s (whic h i s par t o f OUT)

, o r a n on-sit e repositor y t o b e develope d fo r OU 9 

### residentia l soils

. Th e excavate d area s woul d b e backfille d wit h clea n soil

. 

### Soils above actio n level s ma y stil l remai n becaus e th e exten t o f removal i s limite d t o a 2 foo t depth

. Institutiona l controls
, suc h a s th e propose d "overla y district " woul d appl y t o al l area s o f 

### t h e EGW A sites

. Additiona l soi l sampling o r othe r activitie s ma y be required
, whic h woul d be conducte d o r funde d b y Asarco
, in orde r t o be consisten t wit h th e developmen t plans

. Th e cost f o r potentia l futur e remediatio n wa s no t include d in th e cost estimat e fo r Alternativ e 4 becaus e o f t h e man y uncertaintie s an d unknown s associate d wit h potentia l futur e remediatio n effort

. Th e 

### effectivenes s o f th e "overla y district, " as wel l as land us e changes
, an d plans/proposal s fo r futur e lan d us e at eac h site , woul d b e monitore d and evaluate d a s par t o f the five-yea r revie w process

.



## DS-Z :10. 0

SUMMAR Y O F COMPARATIV

E ANALYSI S O F ALTERNATIVE S 

### Sectio n 300.430(e)(9 ) o f th e NC P requires tha t th e EP A evaluat e an d compar e th e remedia l cleanu p alternative s base d o n th e nine criteri a liste d below

. Th e firs t tw o criteria , (1 ) overal l 

### protectio n o f human healt h an d th e environmen t an d (2 ) complianc e wit h applicabl e o r relevan t a n d appropriate requirement s (ARAR)

, ar e threshol d criteri a tha t mus t b e me t fo r th e Selecte d Remedy

. Th e Selecte d Remed y mus t the n represen t th e best balanc e o f th e remainin g primary balancin g an d modifyin g criteria

. 10. 1 NC P EVALUATIO N

AN D COMPARISO N CRITERI A
10.1. 1 Threshold Criteri a 1

. Overal l protectio n o f huma n healt h an d th e environmen t addresse s whethe r eac h alternativ e provide s adequat e protectio n o f human healt h an d th e environmen t an d describe s ho w risks pose d throug h eac h exposur e pathwa y ar e eliminated
, reduced
, o r controlledjjhroug h treatment , engineerin g controls
, and/o r Institutiona l Controls

. 2

. Complianc e

wit h ARARs addresse s whethe r o r no t a remed y wil l compl y wit h identifie d 

### federa l an d stat e environmenta l an d citin g law s an d regulations

. 10.1. 2 Primary Balancin g Criteri a 3

. Long-ter m effectivenes s an d permanenc e refer s t o expecte d residua l risk an d th e abilit y o f
a remed y t o maintai n reliabl e protectio n o f human healt h an d th e environmen t ove r time , once clean-u p level s have been met

. Thi s criterio n include s th e consideratio n o f residua l ris k tha t wil l remai n o n sit e followin g remediatio n an d th e adequacy an d reliabilit y o f controls

. 4

. Reductio n o f toxicitv

. mobility
, an d volum e throug h treatmen t refer s t o anticipate d performanc e o f th e treatmen t technologie s tha t ma y be include d as par t o f a remedy

. 5

. Short-ter m effectivenes s addresse s th e perio d o f tim e neede d t o complet e th e remed y an d
an y advers e impac t o n human healt h an d th e environmen t tha t ma y be pose d durin g th e constructio n an d implementatio n perio d unti l cleanu p goal s ar e achieved

. 6

. Implementabilit v

refer s t o th e technica l an d administrativ e feasibilitie s o f a remedy
, includin g th e availabilit y o f material s an d service s neede d t o carr y ou t a particula r option

. 7

. Cos t evaluate s th e estimate d capita l costs , operatio n an d maintenanc e (O&M ) costs , an d presen t wort h cost s o f eac h alternative

.

DS-2 410.1. 3

Modifyi n Criteri a 

### 8

. Stat e acceptanc e indicate s whethe r th e Stat e (CDPHE)

, base d o n it s revie w o f th e information
, concurs with
, opposes , o r has n o commen t o n th e preferre d alternative

. 9

. Communit y acceptanc e i s base d o n whethe r communit y concerns ar e addresse d b y the Selecte d Remed y an d whethe r o r no t th e communit y has a preferenc e fo r a remedy

. 10. 2 EVALUATIN

G TH E ALTERNATIVE S

WIT H TH E NC P CRITERI A 

### T h e sectio n summarizes th e evaluatio n an d compariso n o f th e OU 5 EG A alternative s agains t th e nin e NC P criteria

. Th e followin g subsection s ar e a brie f summar y o f th e evaluatio n an d compariso n an d compariso n o f th e OU 5 EGW A alternative s agains t eac h criteria

. Additiona l 

### detail s evaluatin g th e alternative s ar e presente d i n th e FFS

. Tabl e 2 provide s a compariso n o f th e nine remedia l actio n alternative s an d th e nin e NC P criteria

. Informatio n fo r this sectio n wa s obtaine d fro m th e Fina l FF S OU 5 EGW A Site s (MFG

, 1999 ) an d th e Propose d Pla n fo r OU 5 EGW A sit e (EPA

, 2000)

. 10.2. 1 Overal l Protectio n o f Huma n Health an d th e Environmen t 

### Thi s criterio n i s base d o n th e leve l o f protectio n o f human healt h an d th e environmen t afforde d b y eac h alternative

. A s shown i n Table 2, Alternative s 2, 3, an d 4 woul d mee t the RAOs

. Al l o f the alternative s woul d contro l airborn e transport , erosion , an d metal s leachin g fro m contaminate d 

### material s becaus e n o significan t pathway fo r transpor t o f constituent s fro m sla g o r soil t o othe r environmenta l medi a hav e been identifie d (MFG

, 1999)

. Alternative s 3 an d 4 woul d provid e additio n benefi t b y eliminating th e potentia l fo r airborn e transport , erosion , an d metal s leachin g 

### fro m contaminate d materials

. A l l o f th e alternative s woul d contro l contaminan t exposur e t o animal s an d aquatic lif e becaus e th e potentia l risk s t o th e terrestria l receptor s throug h direc t contac t o f certain sources a t OU 5 ar e considere d low

. Alternative s 3 an d 4 woul d provid e incrementa l reductio n i n ris k throug h 

### eliminatio n o f direc t contac t o f limite d sources
. Sinc e th e EGW A site s ar e currentl y vacan t an d ma y hav e onl y intermitten t recreational use , Alternative s 1 an d 2 woul d preven t an y significan t direc t exposur e o f th e populatio n t o elevate d concentratio n o f contaminant s in th e surfac e soil becaus e th e averag e metal s concentration s in soil 

### d o no t excee d risk-base d actio n leve l fo r recreationa l use
. On e sampl e locatio n a t th e Elgi n Smelte r sit e has bee n identifie d as havin g lea d an d arsenic concentration s in soil tha t excee d th e 

### actio n leve l fo r recreationa l use
. Th e Elgi n Smelte r sit e is privat e propert y an d wil l b e evaluate d i n 200 1 as par t o f th e five-yea r sit e review

. Alternative s 3 an d 4 woul d provid e additiona l protectio n unde r current lan d us e b y reducin g th e potentia l risk associate d wit h th e isolate d area s o f soi l wit h elevate d metal s concentrations

. Unde r futur e lan d use, Alternativ e 1 (n o action ) may 

### resul t in unacceptabl e exposure

. Th e institutiona l control s in Alternative s 2 , 3 , an d 4 woul d maintai n protectivenes s unde r futur e lan d use
.
DS-2 5Alternativ e

1 woul d no t provid e overal l protectio n o f publi c healt h an d th e environmen t becaus e 

### thoug h slag
, non-residentia l are a soils
, an d residentia l are a soil s in thei r existin g conditio n ar e no t considere d a sourc e o f environmenta l o r human healt h risk
, this alternativ e woul d no t ensur e protectio n unde r potentia l futur e lan d use
. Al l o f th e alternatives
, excep t Alternativ e 1 (N o Action)
, woul d provid e adequat e protectio n o f human healt h an d th e environment

. Alternativ e 2 woul d provid e additiona l protectio n becaus e institutiona l control s woul d hel p ensur e protectio n unde r futur e lan d use
. Alternative s 3 an d 4 woul d provid e minima l additiona l benefi t unde r current sit e condition s an d lan d use s b y isolating an d removin g area s o f soil wit h elevate d metal s 

### concentrations , respectively

. 10.2. 2 Complianc e wit h Applicabl e o r Relevan t an d Appropriat e Requirement s Thi s criterio n i s base d o n complianc e wit h chemical-
, location-
, an d action-specifi c ARARs

. ARARs ar e presente d in Table s 3 throug h 5

. Alternative s 2, 3, an d 4 woul d compl y wit h al l ARARs

. 10.2. 3 Long-Ter m Effectivenes s an d Permanenc e Unde r futur e us e scenarios , Alternativ e 2 woul d provid e long-ter m protectio n an d permanenc e 

### usin g th e institutiona l controls
, whic h woul d rel y o n th e success o f th e "overlay district " an d woul d requir e som e administrativ e maintenanc e an d review

. Alternativ e 3 woul d provid e additiona l long-ter m protectio n throug h isolatio n a t th e Elgi n an d Grant/Unio n Smelte r sites

. Alternativ e 4 woul d provid e th e greates t long-ter m protectio n throug h remova l a t th e Elgi n an d Grant/Unio n Smelte r sites

. Institutiona l control s woul d stil l b e require d i n .Alternativ e 3 t o protec t t h e containmen t barrie r (i.e.
, soi l cover ) an d in Alternativ e 4 becaus e th e remova l activitie s woul d b e limited

. I f th e respons e activitie s fo r Alternativ e 3 an d 4 wer e performe d in advanc e o f development
, thes e activitie s ma y no t correspon d t o th e ultimat e us e o r configuratio n o f th e lan d unde r develope d sit e conditions

. Alternativ e 3 an d 4 woul d requir e some leve l o f inspectio n an d maintenanc e t o achiev e permanence

. 10.2. 4 Reductio n o f Toxicity

, Mobility
, o r Volum e Throug h Treatmen t N o treatmen t processe s ar e bein g considere d t o reduc e toxicity , mobility
, o r volum e o f slag
, non 

### residentia l are a soils
, o r residentia l are a soils

. 10.2. 5 Short-Ter m Effectivenes s T h e short-ter m effectiveness
, base d o n disturbanc e durin g implementation
, woul d b e goo d fo r Alternative s 3 an d 4 , bu t Alternativ e 4 woul d pos e a greate r short-ter m risk durin g th e transportatio n o f contaminate d materials

. Alternative s 1 an d 2 woul d no t have an y disturbance

. 10.2. 6 Implementability A l l alternative s woul d b e relativel y eas y t o implement

. Lak e Count y an d th e Cit y o f Leadvill e hav e agree d t o implemen t th e institutiona l control s in th e for m o f th e '"overla y district/ a s describe d in .Alternative s 2

. 3 , an d 4

. I n addition
, institutiona l control s fo r .Alternative s 2

. 3

. an d 4 DS-2 6

### woul

d b e eas y t o implemen t becaus e Asarc o woul d hel p fun d th e "overla y district " an d fun d an y potentia l screenin g (e.g.
, soi l sampling) an d remediation

. Alternative s 3 an d 4 woul d requir e mor e tim e an d effor t t o implemen t compare d t o Alternativ e 2 becaus e th e area s wit h elevate d metal s concentration s hav e no t been specificall y quantified

. However
, Alternative s 3 an d 4 coul d probabl y stil l be performe d in on e constructio n seaso n wit h conventiona l constructio n equipment

. 10.2. 7 Cos t 

### Thi s criterio n evaluate s th e estimate d capital
, O&M

, an d presen t wort h cost s o f eac h alternative

. Presen t wort h cost s rang e fro m zer o (Alternativ e 1 ) t o $181,66 8 (Alternativ e 4)

. Th e presen t 

### wort h o f post-remova l sit e contro l cost s fo r a 30-year perio d wer e calculate d assumin g a 5 percen t discoun t rate

. 10.2. 8 Stat e Acceptanc e 

### T h e Stat e ha s been consulte d throughou t this process

. Th e Stat e i s awar e o f EPA' s selecte d 

### remed y and ha s chose n t o mak e no furthe r comment

. 10.2. 9 Communit y Acceptanc e Publi c commen t o n th e RI/F S an d Propose d Pla n wa s solicite d durin g a forma l publi c commen t 

### perio d extendin g fro m Jul y 2 7 t o Augus t 28 , 1999

. N o comment s fro m th e communit y wer e receive d durin g th e forma l publi c commen t period

.

DS-2 711. 0 PRINCIPA

L THREA T WASTE S 

### T h e NC P establishe s a n expectatio n tha t EP A wil l us e treatmen t t o addres s th e principa l threat s pose d by th e sit e whereve r practicabl e (NC P §300.430(a)(l)(iii)(A))

.

Identifyin g principa l threa t wastes combine s concept s o f bot h hazard an d risk

. I n general
, principa l threa t wastes ar e thos e sourc e material s considere d t o be highl y toxi c o r highl y mobil e tha t generall y cannot be containe d i n a reliabl e manne r o r woul d presen t a significan t ris k t o human healt h o r th e environmen t shoul d 

### exposur e occur
. Conversely

, non-principa l threa t waste s ar e thos e sourc e material s tha t generall y ca n be reliabl y containe d an d tha t woul d presen t onl y a lo w ris k i n th e even t o f exposure

. Th e manner in whic h principa l threat s ar e addresse d generall y wil l determin e whethe r th e statutor y 

### preferenc e fo r treatmen t a s a principa l elemen t i s satisfied

. T h e sourc e material s identifie d a t th e OU 5 EGW A sit e includ e slag
, non-residentia l are a soils
, an d residentia l are a soil

. Thes e sourc e material s d o no t constitut e principa l threa t wastes ; hence
, they 

### ar e considere d non-principa l threa t wastes

.

DS-2 812. 0 SELECTE D REMEDY 

### Based upo n consideratio n o f CERCL A requirements , th e detaile d analysi s o f alternatives
, an d publi c comments , EP A ha s determine d tha t th e Institutiona l Control s alternativ e presente d i n th e 

### Propose d Plan

, wit h n o modifications
, is th e appropriate remed y fo r th e slag
, non-residentia l are a soils
, an d residentia l are a soil s a t th e OU 5 EGW A site s withi n th e Californi a Gulc h Superfiin d Site

. Lak e Count y and/o r Cit y o f Leadvill e zonin g ordinance s wil l b e modifie d t o creat e a zonin g "overla y district " t o provid e a screenin g proces s t o identif y propertie s where specia l precaution s 

### o r requirement s ma y be necessar y an d a mechanis m t o notif y owner s and/o r developer s o f thes e requirements

. An y samplin g o r respons e action s wil l be conducte d o r funde d b y Asarco
, consisten t wit h th e developmen t plans

. 

### T h e Institutiona l Control s alternativ e i s protectiv e o f human healt h an d th e environmen t an d i s considere d effectiv e becaus e sla g in it s existin g conditio n doe s no t presen t a significan t ris k t o huma n healt h o r th e environment

. I n addition
, n o significan t pathway s fo r transpor t o f COC s 

### fro m non-residentia l an d residentia l are a soil s o r othe r environmenta l medi a have been identifie d
an d averag e metal s concentration s i n soil at eac h sit e ar e wel l .belo w th e risk-base d sit e actio n level s fo r recreatio n us e scenario , which i s consisten t wit h current uses
. Th e "overla y district, " 

### unde r potentia l futur e us e scenarios , wil l ensure tha t an y necessar y precaution s o r requirement s 

### a r e followe d fo r thos e relativel y smal l area s o f soil wit h lea d o r arseni c concentration s exceedin g thei r risk-base d actio n levels
, which ma y presen t a potentia l human healt h risk

. 12. 1 RATIONALE

FO R SELECTE D REMED Y 

### Based upo n consideratio n o f th e requirement s o f CERCL A an d th e NCP

, th e detaile d analysi s o f 

### alternatives
, an d publi c comments , EP A ha s determine d tha t Alternativ e 2 - Institutiona l Control s presente d i n th e Propose d Pla n is th e appropriate remed y fo r th e slag
, non-residentia l are a soils
, a n d residentia l are a soil s withi n th e OU 5 EGW A sites

. Alternativ e 2 eithe r meet s o r exceed s 

### benefit s associate d wit h th e selectin g criteri a compare d t o th e majorit y o f th e othe r alternatives

. T h e approac h fo r wast e lef t i n plac e a s describe d i n Alternativ e 2 is consisten t wit h the.approac h
used i n th e LCCH P an d othe r area s withi n th e Californi a Gulc h Superrun d Site where wast e wa s 

### lef t in place

. Institutiona l control s woul d stil l b e require d fo r Alternative s 3 an d 4 becaus e Alternativ e 3 involve s a soi l cover barrier an d th e removal activitie s fo r Alternativ e 4 woul d be 

### limited

. Alternativ e 2 i s les s expensiv e tha n Alternative s 3 an d 4

. Thi s selecte d remed y wil l reduc e risk t o human healt h an d th e environmen t throug h th e following :
• A s required
, Alternativ e 2 meet s th e threshol d cleanu p evaluatio n criteri a (overal l protectio n o f human healt h an d th e environmen t an d complianc e wit h ARARs)

. 

### • Unde r Alternativ e 2 , potentia l risk s t o huma n healt h an d th e environmen t woul d be controlle d throug h implementatio n o f sampling o r appropriate response'action s 

### consisten t wit h th e developmen t o f a site

. • Alternativ e 2 woul d b e permanen t an d provid e long-ter m effectivenes s consisten t wit h futur e post-developmen t

sit e condition s an d lan d use
. DS-2 9

### T h e Selecte d Remed y bes t meet s th e entir e rang e o f selectio n criteri a an d achieves
, i n EPA' s determination
, th e appropriat e balanc e considerin g site-specifi c condition s an d criteri a identifie d i n CERCL A an d th e NCP

, as provide d in Sectio n 13.0 , Statutor y Determinations

. 12. 2 DESCRIPTIO

N O F SELECTE D REMEDY 

### Institutiona l Control s wil l b e establishe d a s th e Selecte d Remed y t o war n o f potentia l hazard s an d t o maintai n th e effectivenes s o f th e remed y b y limiting access t o o r us e o f th e propert y (curren t
a n d potentia l futur e lan d us e scenarios)
, including temporar y an d permanen t measures
. Institutiona l Control s involv e restrictin g access o r activitie s tha t coul d resul t i n huma n contac t wit h th e slag
, non-residentia l are a soil s an d residentia l area soil s o r increas e th e potentia l fo r leachin g fro m th e sla g piles
, non-residentia l are a soils
, an d residentia l are a soils

. Thi s alternativ e include s measures t o provid e informatio n t o current and/o r futur e lan d owner s regardin g environmenta l condition s a t th e site , an d t o ensur e tha t i f thes e site s ar e develope d an y necessar y specia l precaution s o r requirement s ar e followed

. Lak e Count y and/o r Cit y o f Leadville zonin g ordinance s wil l b e modifie d t o creat e a zonin g "overla y district " t o provid e a screenin g proces s t o 

### identif y propertie s where specia l precaution s o r requirement s ma y be necessar y an d a mechanis m t o notif y owners and/o r developer s o f thes e requirements

. Th e requirement s wil l includ e condition s that mus t b e met t o ensur e protectivenes s and ma y requir e additiona l samplin g or respons e actions , t o b e conducte d o r funde d b y Asarco
, consisten t wit h th e developmen t plans

. A n y sampling o r respons e action s wil l b e conducte d o r funde d b y Asarco
, consisten t wit h th e 

### developmen t plans

. A s th e EGW A site s ar e develope d o r zonin g change s ar e implemented
, th e area s wit h th e elevate d metal s concentration s wil l b e addresse d unde r th e procedure s an d requirement s o f th e "overla y district. " Th e effectivenes s o f th e "overla y district, " a s wel l a s lan d u s e changes
, an d plans/proposal s fo r futur e lan d us e a t eac h site , wil l be monitore d an d evaluate d
a s par t o f th e five-yea r revie w process

. EPA

, upo n consultatio n wit h CDPHE

, wil l revie w an d approv e propose d respons e activities

. A t th e Wester n Zin c Smelte r sit e (currentl y zone d Urba n Residential ) an d th e Arkansa s Valle y Hillsid e Sla g Pil e sit e (currentl y zone d Business)

, ther e is n o evidenc e tha t soil contaminatio n 

### exist s i n exceedanc e o f establishe d risk-base d actio n level s associate d wit h lan d us e scenario s consisten t wit h th e curren t zonin g o f thes e tw o site

. A t th e Grant/Unio n (currentl y zone d Residential ) an d th e Elgi n (currentl y zoned Business ) Smelte r sites , soil sampling dat a indicat e tha t whil e averag e concentration s o f metal s in soil (in th e 0 t o 6 inch dept h interval ) ar e belo w th e establishe d risk-base d actio n level s fo r a residentia l lan d us e scenario , severa l smal l isolate d areas exhibit lea d and/o r arsenic concentration s tha t excee d th e risk-base d actio n level s fo r residentia l
a n d commercial/industria l

us e scenarios , respectively

. A s state d previously
, al l o f th e OU 5 EGW A site s ar e currentl y vacant

. 

### Propose d control s fo r th e Grant/Unio n an d Wester n Zin c Smelte r sites , whic h ar e currentl y zone d residentia l an d essentiall y surrounde d b y OU9

, wil l involv e includin g thes e site s i n th e overla y district

. I f an d whe n futur e remediatio n occurs , Asarc o wil l conduc t o r fun d th e respons e activities , consisten t wit h th e procedure s an d requirement s o f th e LCCHP

. Thes e activitie s woul d b e funde d b y Asarc o separat e fro m th e LCCH P trus t fund

.T h e

Elgi n Smelte r an d Arkansa s Valle y Sout h Hillsid e Sla g Pil e site s ar e locate d i n th e Lak e 

### Count y busines s zonin g distric t (commercial/industria l

use ) an d ar e no t likel y t o be re-zone d fo r 

### residentia l use
. I f th e Elgi n Smelte r site , in th e future
, wa s include d in a n are a o f propose d development
, incidenta l constructio n activitie s ma y adequatel y contain/cove r impacte d soi l o r 

### reduc e constituen t concentration s i n th e uppe r soil layer
, thereb y reducin g risks associate d wit h incidenta l soi l ingestion

. A dee d notic e o r forma l notificatio n t o th e propert y owner wil l be considere d fo r th e Elgi n Smelte r sit e t o provid e availabl e sit e characterizatio n informatio n t o th e 

### owner fo r consideratio n i n plannin g futur e development

. A n O& M progra m wil l b e developed

. O& M activitie s wil l involv e creatio n an d maintenanc e o f t h e "overla y district " fo r th e institutiona l control

. 12. 3 ESTIMATE D

REMEDY COST S T h e detaile d cost estimat e an d presen t wort h analysi s fo r Alternativ e 2 , th e Selecte d Remedy

, ar e 

### presente d in Table s 6 an d 7 , respectively

. Th e ne t presen t valu e o f th e estimate d capita l an d operatin g cos t fo r a 30-year perio d i s approximatel y $85,496

. Th e cost fo r a respons e actio n o f this natur e woul d includ e administrativ e expense s t o obtai n zonin g and/o r dee d restrictions

. Cost s 

### f o r futur e respons e actions , i f any, ar e no t include d in thi s estimat e becaus e o f th e man y uncertainties

. Thes e futur e respons e actions , i f any , wil l b e funde d b y Asarco

. Th e Selecte d Remed y is anticipate d t o b e implementabl e immediatel y upo n finalizatio n o f th e overla y district

. 

### T h e informatio n in this cost estimat e tabl e i s base d o n th e best availabl e informatio n regardin g th e anticipate d scop e o f th e remedia l alternative

. Change s in th e cos t element s ar e likel y t o occur as a 

### resul t o f ne w informatio n an d dat a collecte d durin g th e engineerin g desig n o f th e remedia l alternative

. Majo r change s ma y be documente d i n th e for m o f a memorandu m i n th e 

### Administrativ e Recor d file
, a n Explanatio n o f Significan t Difference

, o r a ROD amendment

. Thi s i s an order-of-magnitud

e engineerin g cost estimat e tha t i s expecte d t o b e withi n +50 t o -3 0 percen t o f th e actua l projec t cost

. 12. 4 EXPECTE D OUTCOM E O F TH E SELECTE D REMED Y 

### Sinc e th e EGW A site s ar e currentl y vacant wit h onl y intermitten t recreatio n use, institutiona l control s wil l b e relie d upo n fo r futur e developmen t an d lan d us e t o maintai n th e protectio n o f 

### human healt h an d th e environment

. A s th e EGW A site s ar e develope d o r zonin g change s ar e implemented
, th e .area s wit h th e elevate d metal s concentration s wil l b e addresse d unde r th e procedure s an d requirement s o f th e "overla y district.' 1 I f an d when futur e remediatio n occur s a t 

### t h e Grant/Unio n an d Wester n Zin c Smelte r sites , which ar e currentl y zone d residential
, Asarc o wil l conduc t o r fun d th e respons e activitie s consisten t wit h th e procedure s an d requirement s o f 

### t h e LCCHP

. Thes e activitie s wil l b e funde d by Asarc o separat e fro m th e LCCH P trus t fund

.

DS-3 113. 0 STATUTOR Y

DETERMINATION

S 

### Unde r CERCL A Sectio n 121 , EP A mus t selec t a remed y tha t i s protectiv e o f human healt h an d t h e environment , tha t complie s wit h ARARs

, i s cost effective
, an d utilize s permanen t solution s an d alternativ e treatmen t technologie s o r resourc e recover y technologie s t o th e maximu m exten t practicable

. I n addition
, CERCL A include s a preferenc e fo r remedie s tha t includ e treatmen t which permanentl y an d significantl y reduce s th e volume
, toxicity , o r mobilit y o f hazardou s waste s a s a principa l element

. 

### T h e followin g section s discus s ho w th e Selecte d Remed y meet s statutor y requirements

. 13. 1 PROTECTIO N

OF HUMA N HEALT H AN D TH E ENVIRONMEN

T T h e Selecte d Remed y i s protectiv e o f huma n healt h an d th e environment , an d i s considere d effectiv e becaus e (1 ) sla g i n it s existin g conditio n doe s no t presen t a significan t ris k t o huma n healt h o r th e environment , (2 ) n o significan t pathway s fo r transpor t o f COC s fro m soil o r othe r 

### environmenta l medi a hav e been identified
, an d (3 ) th e EGW A site s ar e currentl y vacant ; however
, t h e site s ma y b e intermittentl y use d fo r recreation

. On e sampl e locatio n a t th e Elgi n Smelte r sit e 

### has been identifie d as havin g lea d an d arseni c concentration s i n soi l tha t excee d th e actio n leve l f o r recreationa l use
. Th e Elgi n Smelte r sit e i s privat e propert y an d wil l b e evaluate d in 200 1 as par t o f th e five-yea r sit e review, an d (4 ) as th e lan d us e changes
, th e institutiona l control s wil l 

### ensur e tha t wast e lef t in plac e wil l be addresse d t o preven t exposur e t o human health

. T h e Selecte d Remed y woul d contro l airborn e transport , erosion , an d metal s leachin g fro m contaminate d material s becaus e n o significan t pathway fo r transpor t o f constituent s fro m sla g o r soil t o othe r environmenta l media hav e bee n identifie d (MFG

, 1999)

. I n addition
, th e Selecte d Remed y woul d contro l contaminan t exposur e t o animal s an d aquatic lif e becaus e th e potentia l risks t o th e terrestria l receptor s throug h direc t contac t o f certain sources a t OU 5 ar e considere d 

### low

. Unde r current lan d use, Th e Selecte d Remed y woul d preven t direc t exposur e o f th e populatio n t o elevate d concentratio n o f contaminant s in th e surfac e soil becaus e th e averag e metal s concentration s in soil d o no t excee d risk-base d actio n leve l fo r recreationa l use
. Th e Selecte d Remed y woul d maintain protectivenes s unde r futur e lan d use
. 13.2 COMPLIANC E

WIT H ARARs T h e Selecte d Remed y wil l compl y wit h al l ARAR s identifie d in Table s 3 , 4 , an d 5

. N o waive r o f 

### ARARs wil l b e necessary
. Fina l performanc e standard s wil l no t includ e ARARs fo r Site-wid e Surfac e Wate r an d Groundwate r o r requir e a specifie d decreas e in poin t o r non-poin t sourc e loading s o f COC s t o Site-wid e Surfac e Wate r an d Groundwate r (USCD

, 1994)

. I t wa s agree d tha t th e decisio n o n remediatio n o f Site-wide Wate r Qualit y (OU12 ) woul d b e mad e betwee n th e E P A an d th e PRP s an d memorialize d in th e C D onl y afte r remedie s fo r sourc e remediatio n wer e 

### selecte d an d implemente d a t eac h OU

. A s a result
, specifi c wate r qualit y goal s fo r surfac e stream s an d ground-wate r hav e no t bee n establishe d a t thi s time

.

DS-3 2

### 13. 3 COS T EFFECTIVENES

S E P A ha s determine d tha t th e Selecte d Remed y is cost effectiv e i n mitigatin g th e principa l risk s 

### pose d b y slag
, non-residentia l are a soils
, an d residentia l are a soils

. Sectio n 300.430(f)(ii)(D

) o f t h e NC P require s evaluatio n o f cost effectiveness

. Overal l effectivenes s i s determine d b y th e followin g thre e balancin g criteria : long-ter m effectivenes s an d permanence , reductio n o f toxicity , mobility
, an d volum e throug h treatment ; an d short-ter m effectiveness

. Overal l effectivenes s i s 

### the n compare d t o cost t o ensure tha t th e remed y i s cost effective

. Th e Selecte d Remed y meet s t h e criteri a an d provide s fo r overal l effectivenes s i n proportio n t o it s cost

. Th e estimate d cost fo r 

### t h e Selecte d Remed y i s $85,496

. 13. 4 UTILIZATIO N

O F PERMANEN T SOLUTION S AN D ALTERNATIV

E TREATMEN T TECHNOLOGIE S

(O R RESOURC E RECOVER Y 

### TECHNOLOGIES ) TO TH E MAXIMU M EXTEN T POSSIBL E N o remedia l actio n i s necessar y t o ensur e protectio n o f human healt h an d th e environment

. Institutiona l control s allo w fo r managemen t o f th e sit e i f th e lan d us e changes

. Moreover
, sinc e th e slag
, non-residentia l are a soils
, an d residentia l are a soil s wil l remai n o n sit e wit h n o treatment , t h e Selecte d Remed y wil l requir e a five-yea r revie w unde r Sectio n 121(c ) o f CERCL A an d Sectio n 300.430(f)(4)(ii ) o f th e NCP

. 13. 5 PREFERENC E

FO R TREATMEN T A S A PRLNCIPA L ELEMEN T Variou s treatmen t option s fo r slag
, non-residentia l are a soils
, an d residentia l are a soil s wer e considere d i n th e F S process ; however
, du e t o th e nature an d size o f th e slag
, non-residentia l are a soils
, an d residentia l are a soils
, thes e option s wer e determine d t o b e eithe r technicall y impracticabl e and/o r no t cost effectiv e (EPA

, 1993)

. 13. 6 FIVE-YEA R REVIE W REQUIREMENT

S 

### Becaus e th e slag
, non-residentia l are a soils
, an d residentia l area soil s wil l remain o n site , th e Selecte d Remed y wil l requir e a five-yea r revie w unde r Sectio n 121(c) o f CERCL A an d Sectio n 300.430(f)(4)(ii ) o f th e NCP

. Th e five-yea r revie w include s a revie w o f al l monitorin g dat a an d


### a n evaluatio n a s t o ho w wel l the Selecte d Remed y i s achievin g the RAO s an d ARARs tha t i t wa s desisne d t o meet

.



## DS- :

### 14. 0

DOCUMENTATIO N

O F SIGNIFICAN

T CHANGE S T h e Propose d Pla n fo r slag
, non-residentia l are a soils
, an d residentia l are a soil s a t th e OU 5 EGW A site s wa s release d fo r publi c comment i n Jul y 2000

. Th e Propose d Pla n identifie d Alternativ e 2 , Institutiona l Controls

, a s th e preferre d alternative

. Comment s wer e receive d 

### durin g th e publi c comment period

. EP A determine d that n o significan t change s t o th e remedy
, as 

### i t was originall y identifie d in th e Propose d Plan

, wer e necessar y o r appropriate

.

DS-3 4

### 15. 0 REFERENCE S Cam p Dresse r & McKe e Inc

. (CDM)

. 1994

. Final Soils Investigation Data Report, California 

### Gulch CERCLA Site, Leadville, Colorado. Prepare d b y CD M fo r Resurrectio n Minin g Company

. July

. 

### Colorad o Climat e Center

. 1997

. Colorad o State University

, Departmen t o f Atmospheri c Sciences

, http://ulysses.atmos.colostate.edu/access.html

. Engineering-Science

,

Inc

. (ESI)

. 1986

. Final Ya k Tunnel/California Gulch Remedial 

### Investigation. Prepare d fo r State o f Colorado

, Departmen t o f Law

. Foothil l Engineerin g Consultants

, Inc

. (FEC)

. 1996a

. Cultural Resources Investigations o f Selected Smelter Sites, Operable Unit 5, California Gulch Superfund Site, Lake County, 

### Colorado. March

. FEC

. 1996b

. Addendum t o Cultural Resources Investigations o f Selected Smelter Sites, Operable Unit 5 , California Gulch Superfund Site, Lake County, Colorado. July

. Golde r and Associate s (Golder)

. 1996a

. Final Surface Water Remedial Investigation Report, California Gulch Site, Leadville, Colorado. May

. Golder

. 1996b

. Final Hydrogeologic Remedial Investigation Report, California Gulch Site, 

### Leadville, Colorado. May

. Lak e County

. 1997

. Lake County Zoning Districts Map

. Lak e Count y Board o f Count y 

### Commissioners

. McCulley

, Fric k & Gilman

, Inc

. (MFG)

. 1999

. Final Focused Feasibility Study fo r Operable Unit 5 EGWA Sites, California Gulch Superfund Site. Prepare d for Asarc o Inc

. Apri l 6

. Morriso n Knudse n Corporatio n (MK)

. 1992a

. Report fo r Lead Slag Pile Remedial Investigation


### a t th e California Gulch Site, Leadville, Colorado. Prepare d for Denver & Ri o Grand e Wester n Railroad

. December

. MK

. 1992b

. Report fo r Zinc Slag Pile Remedial Investigation a t th e California Gulch Site, Leadville, Colorado. Prepare d fo r Denver & Rio Grand e Wester n Railroad s December

. U.S

. Departmen t o f Commerce

. 1990

. Selected Population an d Housing Characteristics. 

### Bureau o f th e Census

. 

### U.S

. Distric t Cour t (USDC)

, Distric t o f Colorado

. 1994

. Civi l Actio n No

. 83-C-2388

, Consen t Decre e wit h Asarco
, Inc.
, Resurrectio n Minin g Company

, Newmon t Minin g Corporation

, a n d th e Res-Asarc o Join t Venture
, Appendi x B : Wor k Are a Managemen t Pla n fo r Asarc o 

### Incorporate d a t th e Californi a Gulc h Superfun d Site

, Leadville

, Colorado

. May

. DS-3 5U . S Environmenta l Protectio n Agency (EPA)

. 2000

. Proposed Plan fo r Oregon Gulch Operable Unit 5 EG WA Sites, California Gulch Superfund Site, Leadville. Colorado. 

### March

. EPA

. 1999

. A Guide t o Preparing Superfund Proposed Plans, Records o f Decision, an d other Remedy Selection Decision Documents. EP A 540-R-98-0 3 1

. July

. EPA

. 1993

. Final Screening Feasibility Study fo r Remediation Alternatives a t th e California Gulch NP L Site, Leadville, Colorado. September

. EPA

. 1988

. Guidance fo r Conducting Remedial Investigations an d Feasibility Studies Under CERCLA. EPA/540/G-89/004

.

Offic e o f Emergency an d Remedia l Response

, Washingto n D.C

. October

. Wals h an d Associates
, Inc

. (Walsh)

. 1993

. Smelter Remedial Investigation, California Gulch Superfund Site, Leadville, Colorado. Prepare d fo r ASARCO

, Inc

. April

. WESTEC

. 1997a

. Smelter Supplemental Remedial Investigation Work Plan, California Gulch CERCL4 Site. Prepare d fo r ASARCO

, Incorporated

. October

. WESTEC

. I997b

. Final Draft Smelter Feasibility Study, California Gulch CERCLA Site. 

### Prepare d fo r ASARCO

, Incorporated

. Januar y 17

. Weston
, Inc

. an d Terr a Technologies

. 1997

. Ecological Risk Assessment fo r th e Terrestrial Ecosystem. California Gulch NP L Site. Leadville, Colorado. Januar y 1997

. Weston
, Ro y F.

, Inc

. (Weston ) 1996a

. Baseline Human Health Risk Assessment fo r th e California Gulch Superfund Site, Risk t o Residents from Lead (Part A)

. Prepare d b y Roy

. F

. Weston
, Inc

. fo r th e EPA

. Januar y 2

. Weston

. 1996b

. Baseline Human Health Risk Assessment fo r th e California Gulch Superfund Site, Risk t o Residents from Contaminants Other Than Lead (Part B)

. Prepare d b y Roy

. F

. Weston
, Inc

. fo r th e EPA

. Januar y 2

. Weston

. 1995a

. Baseline Human Health Risk Assessment fo r th e California Gulch Superfund Site, Part C Evaluation of Worker Scenario and Evaluation of Recreational Scenarios 

### Prepare d by Roy

. F

. Weston
, Inc

. fo r th e EPA

. April

. Weston

. 1995b

. Final Baseline Aquatic Ecological Risk Assessment (BARA), California Gulch, N P L Site. Prepare d b y Roy F

. Weston
, Inc

. fo r EPA

. September

. Weston

. 1991

. Preliminary Human Health Baseline Risk Assessment fo r th e California Gulch N P L Site, Leadville, Colorado. Prepare d b y Roy F

. Weston
, Inc

. fo r th e EPA

. 

### December

.
DS-3 6Woodward-Clyd

e Consultant s (WCC)

. 1992a

. Smelter Site Reconnaissance

Report, California 

### Gulch Site, Leadville, Colorado. WCC

. 1992b

. Final
- Ai r Quality Monitoring Report, California Gulch Site, Leadville. Colorado.

DS-3 7

### FIGURE SDENVER AN D RI O GRAND E • WESTER N

CANTERBUR Y TUNNE L J Turquois e Lak e LEADVILL E DRAINAG E TUNNE L Even s

CALIFORNIA GULC H SUPERFUN

D SITE BOUNDAR Y

0

.5 1. 0 Y A K

TUNNE L CALIFORNIA GULC H

SCAL E I N MILE S 

## Figur e 1 GENERA L SIT E LOCATION MA P Californi a Gulc h Superfun d Sit e Leadvllle

, Colorad o

### Operabl e Units O U 1 - Ya k Tunnel/Wate r Treatmen t Plan t O U 2 • Malta<Gulc h Fluvia l Tailing/Laadvill e Corp

. Mill/Malt a Gulc h Tailin g Impoundment s O U 3 - D&R G Sla g Piles/Railroa d Easement / Railroa d Yar d O U 4 - Uppe r Californi a Gulc h O U 5 - Asarc o Smelters/Sla g Mil l Site s O U 6 - Sta r Ditch/Panros e Dump/ Stra y Hors e <3u!ch/Evan s Gulc h O U 7 - Apach e Tailin g Impoundmen t O U 8 - Lowe r Californi a Gulc h O U 9 • Residentia l Populate d Areas OU10

- Orego n Gulc h OU1 1 -.Arkansas River Valle y Roodplai n OU1 2 - Sit e Wate r Qualit y



### _ _ _ Operabl e Uni t 

### Boundar y



# Figur e 2 

# Californi a Gulc h Superfun d Sit e a n d Operabl e Unit s Leadville

, Colorad o Date : 25-SEP-200 0 M a p File Mama : nassma o oubndrvjv i A' l v8:0. lLEGEN

D APPROXIMAT E OU5 EGW A SIT E BOUNDARIE S FORME R SMELTE R SIT E STREAM/DRAINAG E DIR T ROA D

GRANT/UNIO N SMELTE R SITE WESTER N ZINC SMELTE R SIT E

-ARKANSAS VALLE Y SOUT H HILLSID E SLA G PIL E SCAL E

200 0 200 0

FEE T 

## Rgure S SIT E MA P OPERABL E UNI T 5 EGW A SITES Californi a Gulc h Superfun d Sit e Leadville

, Colorad oC O M PAT H P;V5280-015\OU5\ROO\ECWA\ng4.d«g

08/09/0 0

2000 UPSTREA M

EG- 1 LEGEN

D SIT E FEATURE S SLA G PIL E SLAG VENEE R COK E AND/O R COA L APPROXIMAT E FORME R ELGI N SMELTE R LOCATIO N B I G EVAN S GULC H APPROXIMAT E LOCATIO N O F SURFAC E WATE R SAMPLIN G STATIO N SCAL E

20 0 2 0 0

FEE T

• SOURCE : MK

, 1992a

. 

## Rgure 4 ELGI N SMELTE R LOCATIO N A N D SIT E FEATURE S OPERABL E UNIT S Californi a Gulc h Superfun d Sit e LsacMIle

, Colorad oC O

M PAT H P:\3280-015\OU5\ROO\EGWA\Flg3.dw

g 08/09/0 0



# I l l
GG- 1 A LEGEN

D SITE FEATURE S SLAG PIL E SLAG VENEE R COK E AND/O R COA L FORME R GRANT/UNIO N

SMELTE R LOCATIO N CALIFORNIA GULC H O U 9 - RESIDENTIA

L POPULATE D

AREA S APPROXIMAT E LOCATIO N O F SURFAC E WATE R SAMPLING STATIO N SCAL E

30 0 30 0

FEE T

* SOURCE : MK

, 1992a

. 

## Figure s GRANT/UNIO N SMELTE R 

### LOCATIO N AN D SIT E FEATURE S OPERABL E UNI T 5 Californi a Gulch Superfun d Sit e Leadvilte

, Colorad oC O M PAT H P:\3280-015\OU5\ROD\ECWA\Fig6.dn

g 08/09/0 0C D

M PAT H P:\3208-015\OU5\ROD\ECWA\FTg7.dw

g M\09\0 0

LEADVILL E WATE R TREATMEN T PLAN T

.

LEGEN

D SITE FEATURE S SLAG PIL E 

### ARKANSA S VALLEY SOUT H HILLSID E SLA G PIL E LOCATIO N AN D SIT E FEATURE S 

### OPERABL E UNI T 5 CALIFORNI A GULC H 

### Californi a Gulc h Superfun d Sit e Leadvllle

, Colorad oC O

M PAT H P:\3280-015\OU5\ROO\ECWA\Flg8.d« q 08/09/0 0



# L SEL0 1 0-1 " 1-2 " 2-6 6-12 " A s 2 5 2 5 1 3 2 4 

### P b 15 5 10 1 , 1 7 " 17

LES101 * 0-3F T A s 23 5 C d 7. 6 P b 10,00 0 Z n 26,80 0

———— — * COMPOSIT E SLA G SAMPLE

. S09-00 3 0-1 " 1-2 " 2-6 " 6-12 " A s <250ji m 255 2 211 8 197 6 117 7 <2m m 54 0 50 8 36 7 57 8 C d <250^ m 5 8 7 1 7 9 4 8 <2m m 3 9 3 6 3 0 4 7 P b <250M m 26.153 22.78 8 21.89 7 24.04 7 <2m m 16,09 0 11.52 1 10,43 2 1 6.226 <250M< | 1 2.38 C 10,86 ^ 11.72 2 Z n j

n \

1 1 ,03C / <2m m J 7.51 0 5.60 7 5,79 2 8.03 9 , PG-62 1 

### o-r 1-2 2-6 " 6-12 " 12-18 " A s N O 90. 5 N O 3. 1 N D C d 12. 8 10. 4 7. 1 5. 2 2.9 P b ( 2,33 4 1.35 3 90 8 25 2 5 9 Z n 2.38 1 i 1.68 3 | ) 86 2 ) H 266 X 

# r

321.50 0

SIT E FEATURE S SLA G PIL E SLAG VENEE R COK E AND/O R COA L APPROXIMATE FORME R ELGI N SMELTE R LOCATIO N B IG EVAN S GULC H A

LES10 1 SAMPL E LOCATION S LEAD SLA G R l (MK

, 1992a ) SAMPL E LOCATIO N • SOILS/SMELTE R

R l PRIMAR Y GRI D PG-62 1 (COM

, 1994 ; WALSH

. 1993 ) • SOILS/SMELTE R

R l DISCRET E S09-00 3 (COM

, 1994 ; WALSH

, 1993 ) X SMELTE R SUPPLEMENTA L R l SEL0 1 (WESTEC

, 1997b ) SEL0 2



### , o-r 1-2 " 2-6 " 6-12 " A s 6 4 3 8 2 6 2 3 P b 71 9 20 9 5 7 2 4

,PG-64 3 

### I
, o- r | 1-2 " I 2-6 " j 6-12 " I 12-18 " A s N O 20. 1 24. 5 14. 6 3. 7 C d N D 1. 8 N D N D N D P b 353. 6 154. 9 17 3 37. 4 61. 4 Z n 41 0 20 2 16 3 76. 4 14 9

.SEL0 3 0-1 1-2 " 2-6 6-12 " A s 4 8 5 7 104 10 5 P b 71 5 92 1 1.49 0 1,570

PG-62 0


### o-r 1-2 " 2-6 " 6-12 " 12-18 " A

s <250/an 18 6 27 2 15. 1 7. 7 1 7 <2m m 20 2 10 7 9. 5 5 9 C d <250M m 25. 7 39. 3 7. 3 5. 9 7. 7 <2m m 59. 6 26. 7 5. 9 4. 7 6 P b <250/im 5,08 0 7,45 0 38 3 95. 3 42 9 <2m m 6,660 3,93 0 293 67. 4 2 1 2 Z n <250/im 2,39 0 4,95 0 69 3 63 6 93 9 <2m m 7,09 0 2,31 0 58 5 45 0 70 9 200

NOTES : AL L CONCENTRATION

S AR E I N mg/k g SOLI D MATERIAL UNLESS IDENTIFIE D OTHERWISE

, AL L SAMPLE S AR E SOIL

. N D = NO T DETECTED

. SCAL E

2 0 0 FEE T 

## Figur e 8 RESULT S O F INVESTIGATION S A T 

### T H E ELGI N SMELTE R SIT E OPERABL E UNI T 5 Californi a Gulc h Superfun d Sit e Leadvilte

, Colorad oC O

M PAT H P:\3280-015\Oy5\ROO\ECWA\Rg0.dw g 08/08/0 0 SGU0 1 

### o- r 1-2 " 2-6 6-12 " A s 130 13 6 1 1 5 1 1 6 C d N A N A N A N A P b 4,91 0 4,34 0 4,50 0 4,47 0 Z n N A N A N A N A PG-23 2



### o-r 1-2 " 2-6 6-12 " 12-18 " A s N D N D N D N D N D C d 35. 3 40. 4 35. 8 6. 4 2. 7 P b 5.173. 6 5.575. 6 5,370. 1 6.318. 7 6.451. 0 , Z n '6,224. 7 |6,3 1 1

. 8 6,908. 2 J 1 1,366

, 1 1 ,66 5 I

PG-21 7 

### o-r 1-2 " 2-6 " 6-12 " 12-18 " A s 27. 4 42. 2 79. 3 5 0 6. 3 C d N D

. 5. 9 N D 8.8 4. 9 P b 1,360. 3 1,334. 5 1.377. 0 1,680. 0 1.322. 0 Z n 500. 7 538. 2 626. 2 634. 1 521. 4
PG-21 6 

### o-r 1-2 " - 2-6 " 6-12 " 12-18 " A s N D N D N D 6. 2 24. 1 C d 6.5 4. 6 1. 4 N D 0. 5 P b 642. 7 419. 4 162. 0 69. 2 32. 7 Z n 370. 2 232. 9 132. 3 79. 7 63. 2 . . .'SGUf-01

, f PG-/2 3 G S 1 GGS10 T 0- 3 F T A s 27 2 ,C d P b <0.4 16,00 0 18,30 0 Z n

* COMPOSIT E SLA G SAMPLE

. PG-27 5 

### o- r 1-2 " 2-6 " 6-12 " 12-18 " A s N D N D N D N D N D C d N D 13. 1 N D 6.2 N D P b 2J274. 0 t 2.'061. 7 i 1 ,943. 9

. 1 5J869. 1 981. 1 Z n 1 .650. 2 1,113. 7 923. 6 861. 7 639. 0 PG-25 2 

### o-r 1-2 " 2-6 " 6-12 " 12-18 " A s N D N D 23. 3 N D 7. 5 C d 15. 4 12. 3 9. 8 N D N D j P b 1.32 2 97 1 1,135. 0 556. 0 i J12 5 Z n 2.42 4 1,79 7 1094 55 1 20 5

PG-21 5


### o- r 1-2 " 2-6 " 6-12 " 12-18 " A

s <250/im 88. 5 44.2 18. 2 11. 4 7 <2m m 4 3 31. 1 11. 7 5. 6 5. 3 I C d <250iun '13. 3 1 2 i4. 4 1. 3 0. 6 <2m m 12. 8 10. 1 3. 3 1. 2 0. 6 P b <250/t m 2.12 0 1 .29 0 35 5 14 8 85. 6 <2m m 1.90 0 99 7 228 8 7 67. 4 Z n <250M m 50 5 49 2 28 3 15 6 10 9 <2m m 49 1 43 3 23 3 130 10 2 

### § SCAL E

[

.... . | SIT E FEATURE S SLA G PIL E SLA G VENEE R COK E AND/O R COA L FORME R GRANT/UNIO N

SMELTE R LOCATIO N CALIFORNI A GULC H O U 9 - RESIDENTIAL

POPULATE D

AREAS SAMPL E LOCATION S A LEA D SLA G R l (MK

, 1992a) GGS10 1 SAMPL E LOCATIO N • SOILS/SMELTE R

R l PRIMAR Y GRI D PG-21 7 (COM

, 1994 ; WALSH

, 1993 ) SWELTE R SUPPLEMENTAL

R l (WESTEC

, 1997b ) 30 0 3 0 0

FEE T NOTES : AL L CONCENTRATION

S AR E I N mg/k g SOLI D MATERIAL

. UNLESS IDENTIFIE D OTHERWISE

, AL L SAMPLE S AR E SOIL

. N D = NO T DETECTED

. N A = NO T ANALYZED

.

* SOURCE : MK

, 1992a

. 

## Figur e 9 RESULT S O F INVESTIGATION S A T 

### T H E GRANT/UNIO N SMELTE R SIT E OPERABL E UNI T 5 Californi a Gulch Superiun d Sit e Leadville

, Colorad oC OM PAT H P:\3280-015\QU5\RQD\EGWA\Fig1Q.dwg 08/09/0 0 HSS104 *
0- 3 F T A s 1 1 2 C d 18. 9 P b 79 3 Z n 67.80 0 * COMPOSIT E SLA G SAMPLE

. HSSIO f 0- 3 F T A s 41 4 C d 29. 5 

### P b 73 9 Z n 63,20 0 * COMPOSIT E SLA G SAMPLE

. HSS102 *
0- 3 F T A s 27 7 C d 28. 6 P b 925 Z n 63.30 0 • COMPOSIT E SLA G SAMPLE

. PG-22 3 

### o-r 1-2 2-6 " 6-12 " 12-18 " A s 130. 2 25. 9 31. 9 8. 4 4. 9 C d N D 20. 5 22. 6 N D 4.14 P b 794. 2 60 0 717. 2 121. 4 23. 5 Z n 8,366. 6 4.911. 8 4.706. 7 873. 4 426. 7 HSS103 *
0- 3 F T A s 15 4 C d 2 5 P b 19 2 Z n 70.00 0 • COMPOSIT E SLA G SAMPLE

. PG-20 8 0-1 " 1-2 " 2-6 " 6-12 " 12-18 " A s N D N D N D N D N D C d 19. 6 15. 7 N D 13. 6 13. 5 P b 1.461. 0 1.423. 7 1.529. 5 1.435. 3 1.342. 7 Z n 2,116. 0 2.024. 5 2,016. 9 2.126. 5 1,742. 5 LAKE COUNT Y FAIR GROUND S

APPROXIMA T O F SOI/IDIFIE D B A G HOUSE/ F DUST/MATER I

SIT E FEATURE S £ g ] SLA G PIL E 

### [TIT J SMELTE R DEBRI S ARE A $ 8 & COK E AND/O R COA L SAMPL E

LOCATION S A ZIN C SLA G R l (MK

, 1992b ) HSS10 1 SAMPL E LOCATIO N • SOILS/SMELTE R

R l PRIMAR Y GRI D PG-22 2 (COM

, 1994 ; WALSH

, 1993 ) • SOILS/SMELTE R

R l DISCRET E S22-02 2 (COM

, 1994 ; WALSH

, 1993 ) SMELTE R SUPPLEMENTAL

R l (WESTEC

. 1997b ) X SWZ0 1 S22-00 2
0-1 " 1-2 " 2-6 " 6-12 " A s <250/i m 7 1 5 8 7 5 7 2 <2m m 1 1 2 8 3 5 4

8 3 C d <250fim 3 0 3 1 1 2 6 <2m m 2 0 19 7 4 P b <250jtim 41 0 21 4 135 31 9 <2m m 29 5 13 9 2 9 13 9 Z n <250jim 6.76 5 7,00 5 3,60 6 2,158 <2m m 5.48 3 4,44 4 2.25 7 4,44 4 PG-23 8 

### o-r 1-2 " 2-6 " 6-12 " 12-18 " A s 62 7 125. 7 N D 14. 5 1. 9 C d 4. 8 1'5. 1 6. 6 n

^D N D P b 2,271. 3 1.481. 2 489. 8 21 3 18 6 Z n 14,342. 6 5,637. 5 1,572. 7 245. 1 222. 3


## swzo r GRA B A s 6 0 j C d 4 1 P b 26 0 Z n 5,10 0 SAMPL E O F POTENTIA L FLUE DUS T MATERIAL

. 522-00 1
0-1 " 1-2 " 2-6 " 6-12 " A s <250(i m 261 24 5 13 6 12 2 <2m m 10 7 142 16 4 10 8 C d <250M m 287 33 3 22 9 4 4 <2m m 14 6 207 17 5 3 7 P b <250M m 2,41 5 1.923 1.11 2 536 <2m m 94 1 923 92 9 27 6 Z n <250yu m 53,49 3 63,35 0 37.96 6 1 1 .74 9 <2m m 30,21 3 40,62 9 32,758 8,79 5 PG-22 2 

### o-r 1-2 " 2-6 " 6-12 " 12-18 " A s N D 3. 3 5.6 5 11. 6 N D J G d J N D 

### ; N O

.1 •1. 9 U. 4 \ N D P b 251. 5 82.9 105. 6 415. 6 296. 3 Z n 740. 1 166. 1 164. 5 839. 4 471. 1

SCAL E NOTES : AL L CONCENTRATION

S AR E I N mg/k g SOLI D MATERIAL

. UNLESS IDENTIFIE D OTHERWISE

, AL L SAMPLE S AR E SOI L N D = NO T DETECTED

. 20 0 2 0 0

FEE T 

## Rgurel O RESULT S O F INVESTIGATION S A T T H E WESTER N ZIN C SMELTE R SIT E 

### OPERABL E UNI T 5 Californi a Gulct i Superfun d Sit e Leadvilte

, Colorad oC OM PAT H P:\3280-015\OU5\ROD\EGWA\Fig1 1

.dw g 08/09/0 0 SME-14 7


### o-r 1-2 " 2-6 " 6-12 " SME-14 7


### o-r 1-2 " 2-6 " 6-12 " A s <250/im 19 4 18 1 24 7 18 9 <2m m 142 12 3 1 65 9 9 P b <250/i m 1.49 4 1.17 0 1,59 3 1.299 <2m m 1.63 2 1,11 4 1,49 7 900 

### C d <250/im N D 1 5 N D 2 3 <2m m N D N D N D N D Z n
. <250jim 26 1 17 9 19 2 20 0 <2m m 16 2 N D 13 3 13 3

SIT E

FEATURE S SLA G PIL E

— ••

— CALIFORNI

A GULC H «

SMELTE R

R l (WASH

, 1993 ) SME-U 7 SAMPL E LOCATIO N • SOIL S

INVESTIGATIO N PG-62 1 PRIMAR Y GRI D (COM

, 1994 ) NOTES : AL L CONCENTRATION

S AR E I N mg/k g SOLID MATERIA L UNLESS IDENTIFIE D OTHERWISE

, AL L SAMPLE S AR E SOIL

. N D = NO T DETECTE D PG-04 6 

### o- r 1-2 " 2-6 " 6-12 " 12-18 " A s 397. 5 179. 1 34. 6 10. 9 4.9 C d
14. 1 3. 0 7. 2 N D 0.2 4 P b
2.404. 7 1,323. 1 24 9 37. 8 35. 5 Z n 318. 1 177. 0 112. 8 225. 0 82. 0 LEADVILL E WATE R TREATMEN T PLAN T PG-07 6 

### o-r 1-2 " 2-6 " 6-12 " 12-18 " A s 15 82. 9 39. 3 91. 3 237. 9 C d
4. 1 3.5 7. 6 15. 5 8.3 P b 359. 6 1,315. 6 886. 9 1,479. 3 1,850. 1 Z n 392. 9 768. 8 719. 2 723. 3 431. 4 PG-06 5 

### o- r 1-2 " 2-6 " 6-12 " 12-18 " A s 357. 2 274. 2 33. 3 22. 2 1. 3 C d 16. 5 18. 4 0.2 4 12. 9 10. 0 P b 2,86 5 1.703 490. 8 103. 3 40. 7 Z n 488. 1 378. 1 315. 1 213. 6 157. 6 SME-15 2 0-1 " 1-2 " 2-6 " 6-12 SME-15 2
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— V///////A Figur e 1 3 CONCEPTUAL SIT E MODEL FO R RESIDENTIA L EXPOSUR E Californi a Gulc h Superfun d Site

, Leadville

, Colorad oPRIMAR Y

SOURCE PRIMAR Y

RELEAS E PRIMAR Y TRANSPOR T SECONDAR Y

SECONDAR Y EXPOSUR E SOURCE RELEAS E MEDI A So

l Bd M SpotU d Vountd n *>}« 1 9u « *TMriO T TdU d Od d Uer i Td M Hu b R« l OU M Cn^U r Sampci v Bkj^r t Btoctt- d Groat laird Hnr k Co^ > fhlpmr t Vot e D« v F

IECEN D [ | INCOUPLCT I POrtKtWLL Y COMPLO E

SOURCE : Ecologica l Ris k Assessmen t fo r Terrestria l Ecosyste m (WESTON

, 1997 ) Figur e 1 4 CONCEPTUA L SIT E MODEL ECOLOGICA L RIS K ASSESSMEN T FO R TH E TERRESTRIA L ECOSYSTE M Californi a Gulc h Superfun d Site

, Leadville

, Colorad oTABLE STABL E 1 RESULT S O F SURFAC E WATE R ANALYSE S FO R GEORGI A GULC H AN D EVAN S GULCH O U 5 EGW A SITE S CALIFORNI A GULC H SUPERFUN D SIT E
Tota l Metal s Aluminu m Antimon y Arseni c Bariu m Cadmiu m Chromiu m Coppe r Iro n Lea d Manganes e Mercury Nicke l Seleniu m Silve r Zin c Unit s ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L GG- 1 (Ice-Off

. 1991 ) 279 0 U 40. 6 10 9 4. 6 U 80. 8 400 0 93 2 32 5 U U U 2. 3 118 0 EG- 1 (Sprin g 1991 ) 80. 7 U 1. 3 50. 6 0.8 0 U 7. 5 94. 2 8. 6 U U U U U 1 1 3 EG- 1 (Fal l 1991 ) U U U 75. 5 0.48 U U U U U U U U U 60. 9 EG- 2 (Sprin g 1991 ) 58. 6 U 2. 7 52. 1 0.8 7 U 8. 1 86. 1 8. 2 13. 8 U U U U 10 1 Dissolve d Metal s Aluminu m Antimon y Arseni c Bariu m Cadmiu m Chromiu m Coppe r Iro n Lea d Manganes e Mercury Nicke l Seleniu m Silve r Zin c ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L u.g/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L ug/ L 85. 8 U 11. 2 U 1. 9 U 9. 7 6 1 15. 5 U U U U U 3 4 U

U U 50. 8 0.5 4 U 4. 0 U U U U U U U U U

4. 1 U 69. 3 0.3 2 U U U U U U U U U U U

U U 49. 6 0.46 U 3. 6 U U U U U U U U Majo r Constituent s p H (field ) Alkalinity Calciu m Chlorid e Cyanid e DO C Fluoride Magnesiu m Nitrat e -t

- nitrite as N Potassiu m Silic a Sodiu m Specifi c Conductanc e Sulfat e T D S T SS Tota l Phosphoru s as P S.U

. mg/ L mg/ L mg/ L mg/ L mg/ L mg/ L mg/ L mg/ L mg/ L mg/ L mg/ L umhos/c m mg/ L mg/ L mg/ L mg/ L 8.46 1 9 5 U U U U U 0.0 2 U 3 U 3 5 U 5 0 13 8 0.26 7.7

6 5 8 1 7 U U 1 5 U 8 0.0 4 U 3 U 13 7 5 4 9 6 4 U 8.46

9 8 2 4 U N A 2 0. 1 1 2 U U 1 U 18 9 U 9 6 U U 8.3

2 5 6 1 6 U U 1 6 U 8 0.0 5 U 3 U 13 6 3 5 8 2 4 U Source : Colder

, 1996b

. EG- 1 an d EG-2 : Eva n Gulc h surfac e wate r monitoring locations

. GG-1 : Georgi a Gulc h surfac e wate r monitoring location

. N A : No t analyze d U : No t detecte d ug/ L : microgram s pe r lite r mg/L : milligram s pe r lite r TDS : tota l dissolve d solid s TSS: tota l suspende d solid s umhos/cm : micromho s pe r centimete rTABL E 2 SUMMAR Y O F COMPARATIV

E ANALYSI S O F REMEDIAL ALTERNATIVE S O U5 EGW A SITE S CALIFORNIA GULC H SUPERFUN D SIT E

Evaluatio n Criteri a Alternativ e 1 N o Actio n Alternativ e 2 Institutiona l Control s Alternativ e

3 N o Actio n fo r Slag ; Containmen t fo r Non-Residentia l Are a Soils an d Residentia l Are a Soils ; an d Institutiona l Control s Alternativ e

4 N o Actio n fo r Slag ; Rcmuval/Transport/Disposa l

o f Non

- Residentia l Are a Soils an d Residentia l Are a Soils t o a n On-Sit e Repository ; a n d Institutiona l Control s OVERAL L PROTECTIVENES

S Huma n Healt h Protectio n Airborn e transpor t o f contaminate d material s Erosio n o f contaminate d material s int o loca l wate r courses Metal s leachin g an d migratio n fro m soil int o surfac e wate r Metals leachin g an d migratio n fro m soi l int o groundwale r Contaminan t exposur e t o animal s a n d aquati c lif e N o significan t pathways fo r transpor t o f constituent s fro m sla g o r soil t o othe r environmenta l media hav e bee n identified

. N o significan t pathway s fo r transpor t o f constituent s fro m sla g o r soil t o othe r environmenta l medi a have bee n identified

. N o significan t pathway s fo r transpor t o f constituent s fro m slag o r soil t o othe r environmenta l medi a hav e been identifie d N o significan t pathway s fo r transpor t o f constituent s fro m sla g o r soil t o othe r environmenta l medi a hav e bee n identified

. Potentia l risk t o th e terrestria l receptor s throug h direc t contac t o f certai n sources a t O U 5 ar e considere d low

. N

o significan t pathway s fo r transpor t o f constituent s fro m sla g or soil t o othe r environmenta l media have bee n identified

. N o significan t pathway s fo r transpor t o f constituent s fro m sla g or soi l t o othe r environmenta l media have bee n identified

. N o significan t pathway s fo r transpor t o f constituent s fro m sla g or soil t o othe r environmenta l medi a have bee n identified

. N o significan t pathway s fo r transpor t o f constituent s fro m sla g o r soi l t o othe r environmenta l medi a hav e bee n identified

. Potentia l ris k t o th e terrestria l receptor s throug h direc t contac t o f certai n source s at OU 5 are considere d low

. Containmen t

woul d virtuall y eliminat e potentia l fo r airborn e transpor t o f particle s fro m th e isolate d area s o f soil wit h elevate d metal s concentration

. Containmen t woul d virtuall y eliminat e potentia l fo r erosio n o f material s int o surfac e o r groundwate r fro m th e isolate d
area s o f soi l wit h elevate d metal s concentration

. Conlaiiunen t woul d virtuall y eliminate potentia l fo r metal s leachin g int o surfac e wate r fro m th e isolate d area s o f soil wit h elevate d metal s concentration

. Containmen t woul d virtuall y eliminate potentia l fo r metal s leachin g int o groundwate r fro m th e isolate d area s o f soil wit h elevate d metal s concentration

. Incrementa l reductio n o f risk throug h eliminatio n o f direc t contac t o f limite d
sources
. Remova l woul d virtuall y eliminat e potentia l fo r airborne transpor t o f particle s fro m th e isolate d area s o f soil wit h elevate d metal s concentration

. Remova l woul d virtuall y eliminat e potentia l fo r erosio n o f material s int o surfac e o r groundwate r fro m th e isolate d
area s o f soil wit h elevate d metal s concentration

. Remova l woul d virtuall y eliminate potentia l fo r metal s leachin g int o surfac e wate r fro m th e isolate d area s o f soil wit h elevate d metal s concentration

. Remova l woul d virtuall y eliminate potentia l fo r metal s leachin g int o groundwate r fro m th e isolate d area s o f soil wit h elevate d metal s concentration

. Incrementa l reductio n o f ris k throug h eliminatio n o f direc t contac t o f limite d
sources
. Pag e 1 o f 6TABL E 2 (continued ) SUMMAR Y O F COMPARATIV

E ANALYSI S O F REMEDIA L ALTERNATIVE S O U5 EGW A SITE S CALIFORNIA GULC H SUPERFUND SIT E

Evaluatio n Criteri a Preven t direc t exposur e o f th e populatio n t o elevate d concentratio n o f contaminant s in th e surfac e soil Environmenta l Protectio n Alternativ e

1 N o Actio n Unde r curren t lan d use, averag e metal s concentration s i n soi l d o no t excee d risk

base d actio n leve l fo r a recreationa l use
. Unde r futur e lan d use, n o actio n ma y resul t in unacceptabl e exposure

. N o significan t risk associate d wit h exposur e t o source materials

. Alternativ e 2 Institutiona l Control s Unde r current lan d use , averag e metal s concentration s i n soil d o no t excee d risk-base d actio n leve l fo r a recreationa l use
. Unde r futur e lan d use, Institutiona l Control s woul d maintai n prolectiveness

. Simila r t o Alternativ e 1 , excep t institutiona l control s hel p ensure protectio n unde r futur e lan d use
. Alternativ e

3 N o Actio n fo r Slag ; Containmen t fo r Non-Residentia l Are a Soils an d Residentia l Are a Soils ; an d Institutiona l Control s Containmen t woul d reduc e potentia l risk associate d wit h th e isolate d area s o f soil wit h elevate d metal s concentratio n i f a sit e wer e developed

. Unde r futur e lan d use, Institutiona l Control s woul d maintai n protectiveness

. Simila r t o Alternativ e 1 , excep t institutiona l control s hel p ensur e protectio n unde r futur e lan d use
. Containmen t an d maintenanc e woul d virtuall y eliminat e potentia l fo r ris k t o environment

. Alternativ e 4 N o Actio n fo r Slag ; Removal/Transport/Disposa l

o f Non

- Residentia l Are a Soils an d Residentia l Are a Soils t o a n On-Sit e Repository ; a n d Institutiona l Control s Remova l woul d reduc e potentia l risk associate d wit h th e isolate d area s o f soil wit h elevate d metal s concentratio n i f a sit e wer e developed

. Unde r futur e lan d use , Institutiona l Control s woul d maintai n protectiveness

. Simila r t o Alternativ e 1 , excep t institutiona l control s hel p ensur e protectio n unde r futur e lan d use
. Disposa l woul d virtuall y eliminat e potentia l fo r risk t o environment

. COMPLIANC E WIT H ARAR s Chemical-Specifi c ARAR s Location-Specifi c ARAR s Action-Specifi c ARAR s Othe r Criteri a an d Guidanc e Chemical-specifi c

ARAR s ar e met

. Location-specifi c ARAR s ar e met

. Action-Specifi c ARAR s ar e met

. Non e identified

. Chemical-specifi c ARAR s ar e met

. Location-specifi c ARAR s ar e met

. Action-Specifi c ARAR s ar e met

. Non e identified

. Chemical-specifi c ARARs ar e met

. Location-specifi c ARAR s ar e mel

. Action-Specifi c ARAR s ar e me t Non e identified

. Chemical-specifi c ARAR s ar e met

. Location-specifi c ARAR s ar e me t Action-Specifi c ARAR s ar e met

. Non e identified

.

Pag e 2 o f 6TABL E 2 (continued ) SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVE S O U5 EGW A SITE S CALIFORNIA GULC H SUPERFUN D SIT E

Evaluatio n Criteri a Alternativ e

1 N o Actio n Alternativ e 2 Institutiona l Control s Alternativ e

3 N o Actio n fo r Slag ; Containmen t fo r Non-Residentia l Are a Soils an d Residentia l Are a Soils ; an d Institutiona l Control s Alternativ e

4 N o Actio n fo r Slag ; Removal/Transport/Disposa l

o f Non

- Residentia l Are a Soils an d Residentia l Are a Soils t o a n On-Sit c Repository ; a n d Institutiona l Control s LONG-TER M EFFECTIVENES

S AN D PERMANENC E Airborn e transpor t o f particle s llrosio n ot " material s int o surfac e wate r or groundwale r Metal s leachin g int o surfac e wate r Metals leachin g int o groundwale r Contaminan t exposur e t o animal s a n d aquati c lif e Adequac y an d Reliabilit y o f Control s N

o chang e i n long-ter m effectiveness

. N o chang e i n long-ter m effectiveness

. N o chang e i n long-ter m effectiveness

. Minima l leachin g potential

. N o chang e i n long-ter m effectiveness

. Minima l leachin g potential

. N o chang e i n long-ter m effectiveness

. N o control s over remainin g contamination

. N o reliability

. Simila r

t o Alternativ e 1 , excep t tha t institutiona l control s hel p ensure protectio n unde r futur e lan d use
. Simila r t o Alternativ e 1 , excep t tha t institutiona l control s hel p ensur e protectio n unde r futur e lan d use
. Simila r t o Alternativ e 1 , excep t tha t institutiona l control s hel p ensure protectio n unde r futur e lau d use
. Simila r t o Alternativ e 1 , excep t tha t institutiona l control s hel p ensur e protectio n unde r futur e lan d use
. Simila r t o Alternativ e 1 , excep t Institutiona l control s hel p ensur e protectio n unde r futur e lan d use
. Simila r t o Alternativ e 1 , excep t Institutiona l control s hel p ensur e protectio n unde r futur e lan d use
. Containmen t

woul d provid e goo d long

term effectivenes s an d permanenc e i f maintained

. Containmen t woul d provid e good long

term effectivenes s an d permanenc e i f maintained.

. Containmen t woul d provid e good long

term effectivenes s an d permanenc e i f maintained

. Minima l leachin g potential

. Containmen t woul d provid e good long

term effectivenes s an d permanenc e i f maintained

. Minima l leachin g potential

. Containmen t an d institutiona l control s woul d provid e good long-ter m effectivenes s an d permanence

. Containmen t woul d provid e goo d contro l
o f source materials

. Reliability ca n be hig h i f maintained

. Failur e t o maintai n cover ca n increas e potentia l fo r airborn e transport , erosion , an d leaching

. Institutiona l control s ar e limite d i n effectivenes s du e t o enforceability

. Disposa l

woul d provid e good long-ter m effectivenes s an d permanence

. Disposa l repositor y woul d hav e t o be erosio n resistant

. Long-ter m maintenanc e required

. Disposa l repositor y woul d provid e goo d long-ter m effectivenes s an d permanence

. Long-ter m maintenanc e required

. Minima l leachin g potential

. Disposa l repositor y woul d provid e good long-ter m effectivenes s an d permanence

. Long-ter m maintenanc e required

. Minima l leachin g potential

. Disposa l an d institutiona l control s woul d provid e goo d long-ter m effectivenes s an d permanence

. Disposa l woul d provid e good contro l o f source materials

. Reliability ca n b e hig h i f maintained

. Failur e t o maintai n repositor y ca n increas e potentia l fo r airborn e transport , erosion , an d leaching

. Institutiona l control s ar e limite d i n effectivenes s du e t o enforceabililv

. Pag e 3 o f 6TABL E 2 (continued ) SUMMAR Y O F COMPARATIV

E ANALYSI S O F REMEDIA L ALTERNATIVE S O U5 EGW A SITE S CALIFORNIA GULC H SUPERFUN D SITE

Evaluatio n Criteri a Alternativ e

1 N o Actio n Alternativ e 2 Institutiona l Control s Alternativ e

3 N o Actio n fo r Slag ; Containmen t fo r Non-Residentia l Are a Soil s an d Residentia l Are a Soils ; an d Institutiona l Control s Alternativ e

4 N o Actio n fo r Slag ; Rcrnoval/Transport/Disposa l

o f Non

- Residentia l Are a Soils an d Residentia l Are a Soils t o a n On-Sit e Repository ; a n d Institutiona l Control s REDUCTIO N O F TOXICITY

, MOBILITY

, O R VOLUM E THROUG H TREATMEN T Reductio n o f Toxicily

, Mobility
, o r Volum e Doe

s no t includ e treatment

. Doe

s no t includ e treatment

. Doe

s no t includ e treatment

. Doe

s no t includ e treatment

. SHORT-TER M EFFECTIVENES S Communit y Prelectio n N

o disturbanc e t o th e community

. Unde r

current lan d use, no disturbanc e t o th e community

. Unde r futur e lan d use, potentia l mino r risk t o communit y du e t o increas e i n dus t emission s an d exposur e o f contaminants

. Controllabl e throug h standar d constructio n practices

. Mino r

risk t o communit y du e t o increas e in dus t emission s an d exposur e o f contaminants

. Controllable throug h standar d constructio n practices

. Roa d traffi c woul d increas e over th e short

term

. Mino r risk t o communit y du e t o increas e i n dus t emission s an d exposur e o f contaminants

. Controllable throug h standar d constructio n practices

. Roa d traffi c woul d increas e ove r th e short

term

. Worke r Protectio n N

o risk t o workers

. Unde r

current lan d use , no ris k t o workers

. Unde r futur e lan d use , potentia l fo r inhalatio n o f airborn e particle s an d contac t wit h contaminate d material s durin g respons e activities

. Potentia l

fo r inhalatio n o f airborn e particle s an d contac t wit h contaminate d material s during remedia l activities

. Potentia l

fo r inhalatio n o f airborn e particle s an d contac t wit h contaminate d material s durin g remedia l activities

.
Environmenta l Impact s N

o chang e in short-ter m risk t o th e environment

. Unde r

current lan d use, n o chang e in short-ter m ris k t o th e environment

. Unde r futur e lan d use, potentia l mino r risk t o communit y du e t o increas e in dus t emission s an d exposur e o f contaminants

. Controllabl e tliroug h standar d constructio n practices

. Mino r

risk t o communit y du e t o increas e in dus t emission s an d exposur e o f contaminants

. Controllable throug h standar d constructio n practices

. Road traffi c woul d increas e ove r th e short

term

. Mino r risk t o communit y du e t o increas e in dus t emission s an d exposur e o f contaminants

. Controllable throug h standar d constructio n practices

. Road traffi c woul d increas e over th e short

term

. Pag e 4 o f 6TABL E 2 (continued ) SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVE S O U5 EGW A SITE S CALIFORNIA GULC H SUPERFUN D SITE

Evaluatio n Criteri a Tim e Unti l Actio n is Complete Alternativ e

1 N o Actio n N o t applicable

. Alternativ e 2 Institutiona l Control s Immediate

. Alternativ e 3 N o Actio n fo r Slag ; Containmen t fo r Non-Residentia l Are a Soils an d Residentia l Are a Soils ; an d Institutiona l Control s Immediate

. Alternativ e 4 N o Actio n fo r Slag ; Rcmoval/Transport/Disposa l

o f Non

- Residentia l Are a Soil s an d Residentia l Are a Soil s t o a n On-Sit e Repository ; a n d Institutiona l Control s Immediate

. IMPLEMENTABIL1TY Abilit y t o Construc t an d Operat e Ease o f Doin g Mor e Actio n i f Neede d Abilit y t o Monito r Effectivenes s Abilit y t o Obtai n Approval s an d Coordinat e wit h Othe r Agencie s Availabilit y o f Equipment

, Specialists

, an d Material s Availabilit y o f Technologie s N

o constructio n o r operation

.
Ma y requir e RO D amendmen t i f futur e actio n is taken

. N o monitoring

. N o approva l necessary
.
Non e required

.
Non e require d Unde r

current lan d use, no constructio n o r operation

. Unde r futur e lan d use, relativel y standar d construction , i f needed

. Institutiona l control s allow s fo r futur e respons e actions , i f needed

. Land us e plans/proposal s fo r futur e lan d use woul d b e monitore d a s par t o f th e five-yea r revie w process

. Coordinatio n an d cooperatio n wit h propert y owner s an d loca l agencie s woul d b e necessary
. Non e require d fo r current lan d use
. Standar d equipmen t is readil y availabl e fo r futur e actio n a s required

. Non e require d fo r current lan d use
. Technolog y fo r screenin g an d respons e action s is readil y available

. Relativel y standar d construction

.
Institutiona l control s allow s fo r futur e respons e actions , i f needed

. Monitorin g an d maintenanc e inspection s woul d giv e notic e o f failur e befor e significan t exposur e occurs
. Coordinatio n an d cooperatio n wit h propert y owner s an d loca l agencie s woul d b e necessary
. Standar d equipmen t i s readil y available

.
Containmen t technolog y i s readil y available

. Relativel y standar d construction

.
Institutiona l control s allow s fo r futur e respons e actions , i f needed

. Lan d us e plans/proposal s fo r futur e lan d use woul d b e monitore d a s par t o f the five-yea r revie w process

. Coordinatio n an d cooperatio n wit h properl y owner s an d loca l agencie s woul d be necessary
. Sam e as Alternativ e 2

. Standar d equipmen t i s readil y availabl e

Removal

, transport , an d disposa l tecluiolog y i s readil y available

.
Pag e 5 o f 6TABL E 2 (continued ) SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVE S O U 5 EGW A SITE S CALIFORNIA GULC H SUPERFUN D SIT E

Evaluatio n Criteri a Alternativ e

1 N o Actio n Alternativ e 2 Institutiona l Control s Alternativ e

3 N o Actio n fo r Slag ; Containmen t fo r Non-Residentia l Are a Soils an d Residentia l Are a Soils ; an d Institutiona l Control s Alternativ e

4 N o Actio n fo r Slag ; Removal/Transport/Disposa l

o f Non

- Residentia l Are a Soils an d Residentia l Are a Soil s t o a n On-Sit e Repository ; a n d Institutiona l Control s COS T Capita l Cos t Annua l O& M Cos t Present Wort h Cos t (5 % Ral e o f Return

, 3 0 year period ) $

0 $ 0 $ 0 $33,60 0

$2,50 0 $85,49 6 $83,44 5

$3,50 0 $150,71 4 $129,875 $3,00 0 $181,66 8 STATE ACCEPTANC E Stat e Acceptanc e Alternativ e

no t preferre d b y t h e State

. T h e

Slat e i s awar e o f EPA' s selecte d remed y an d ha s chose n t o mak e no furthe r comment

. T h e

Stat e i s awar e o f EPA' s selecte d remed y an d ha s chose n t o mak e n o furthe r comment

. T h e

Stat e i s awar e o f IZPA' s selecte d remed y an d ha s chose n t o mak e n o furthe r comment

. COMMUNIT Y ACCEPTANC E Communit y Acceptanc e Alternativ e

no t preferre d b y t h e communit y Alternativ e

preferre d b y th e community

. Alternativ e no t preferre d b y th e communit y Alternativ e no t preferre d b y th e communit y

Pag e 6 o f 6TABL E 3 SUMMAR Y O F POTENTIA L CHEMICAL-SPECIFI

C ARAR S O U S EGW A SITE S CALIFORNI A GULC H SUPERFUN D SIT E Standard

, Requirement

, Criteria

, o r Limitatio n Citatio n Potentiall y Applicabl e Potentiall

y Relevan t an d Appropriat e Descriptio n FEDERA L RCR A Subtitl e C 4 0

CF R Par t 261.4(b)(7)an d Sectio n 300 1 (b ) (Bevill Amendment ) N o Y e s T h e

sources o f contaminatio n a t th e OU S EGW A Site s ar e variou s combination s o f t h e following : tailing
, wast e rock
, slag
, an d baghous e flu e dus t fro m processin g o f primary lea d ore
. Based o n 4 0 CF R 261.4(b)(7 ) an d Sectio n 300 1 (b ) (Bevil l Amendments)
, tailing
, wast e rock
, an d slag wast e ar e exclude d fro m RCR A Subtitl e C

. However
, ba g house/flu e dus t identifie d a t th e Wester n Zin c Smelte r sit e i s potentiall y subjec t t o RCR A i f thes e material s fai l TCLP ar e disposed

. Consolidatio n o r on-sit e managemen t o f flu e dus t withi n are a o f contaminatio n woul d no t constitute disposa l and
, therefore
, RCR A subtitle C woul d no t b e applicable

. However
, provision s o f RCR A ar e potentiall y relevan t an d appropriate t o flu e dust

. (Se e action-specifi c ARAR s below)

. Clea n Ai r Act
, Nationa l Primar y an d Secondar y Ambien t Ai r Qualit y Standards 4 0

CF R Par t 5 0 N o N

o Nationa l

ambien t ai r qualit y standard s (NAAQS ) ar e implemente d throug h th e N e w Sourc e Revie w Progra m an d Slat e Implementatio n Plan s (SIP)

. Th e federa l N e w Sourc e Revie w Progra m addresse s onl y majo r sources
. Emission s associate d wit h propose d remedia l actio n a t th e OU 5 EGW A Site s wil l b e limite d t o fugitiv e dus t emission s associate d wit h eart h movin g activitie s durin g construction

. Thes e activitie s wil l no t constitute a majo r source
. Therefore

, attainmen t an d maintenanc e o f NAAQ S pursuan t t o th e Ne w Sourc e Revie w Progra m ar e no t ARARs

. Se e Colorad o Ai r Pollutio n Preventio n an d Contro l Ac t concernin g applicability o f requirement s implemente d throug h th e SIP

.

Pag e 1 o f 2TABL E 3 (continued ) SUMMAR Y O F POTENTIA L CHEMICAL-SPECIFI

C ARAR S O U 5 EGW A SITE S CALIFORNI A GULCH SUPERFUN D SIT E

Standard

, Requirement

, Criteria

, o r Limitatio n Citatio n Potentiall y Applicabl e Potentiall

y Relevan t an d Appropriat e Descriptio n STAT E O F COLORAD O Colorad o Ai r Pollutio n Preventio n an d Contro l A c t 5CC R

1001-14 ; 5CC R 1001-1 0 Par t C (I ) Regulatio n 8 Y e s Pursuan t t o th e Colorad o Ai r Pollutio n Preventio n an d Contro l Act
, applicants fo r constructio n permit s ar e require d t o evaluat e whethe r th e propose d sourc e will
excee d NAAQS

. Applicant s ar e als o require d t o evaluat e whethe r th e propose d activitie s woul d cause a n exceedanc e o f th e Colorad o ambien t standar d fo r paniculat e 1 0 microns o r les s i n aerodynami c diamete r (PM10)

. Constructio n activitie s associate d wit h propose d remedia l actio n a t th e OU 5 EGW A Site s will b e limite d t o generatio n o f fugitiv e dus t emissions

. Colorad o regulate s fugitiv e emission s throug h Regulatio n No

. 1

. Complianc e wit h applicabl e provision s o f t h e Colorad o ai r qualit y requirement s will b e achieve d b y adherin g t o a fugitiv e emission s dus t contro l pla n prepare d i n accordanc e wit h Regulatio n No

. 1

. Thi s pla n wil l discus s monitorin g requirements , i f any , necessar y t o achiev e thes e standards

. Regulatio n No

. 8 set s emissio n limits fo r lead

. Applicant s ar e require d t o evaluat e whethe r th e propose d activitie s woul d resul t i n a n exceedanc e o f thes e standards

. T h e propose d remedia l actio n a t th e OU 5 EGW A Site s is no t expecte d t o excee d t h e emissio n level s fo r lead
, althoug h som e lea d emission s may occur
. Complianc e wit h Regulatio n No

. 8 will b e achieve d b y adherin g t o a fugitiv e emission s dus t contro l pla n prepare d i n accordanc e wit h Regulatio n No

. 1

. Thi s pla n wil l discus s monitorin g requirements , i f any , necessar y t o achiev e thes e standards

.

Pag e 2 o f 2TABL E 4 SUMMAR Y O F POTENTIA L LOCATION-SPECIFI

C ARAR S O U 5 EGW A SITE S CALIFORNI A GULCH SUPERFUN D SIT E Standard

, Requirement

, Criteria

, o r Limitatio n Citatio n Potentiall y Applicabl e Potentiall

y Relevan t an d Appropriat e Descriptio n FEDERA L Nationa l Histori c Preservatio n Ac t (NHPA )
Executiv e Orde r 1159 3 Protectio n an d Enhancemen t o f th e Cultura l Environmen t T h e Histori c an d Archaeologica l Dat a Preservatio n Ac t o f 197 4 Histori c Site s Ac t o f 193 5 T h e Archeologica l Resource s Protectio n Ac t o f 197 9 Executiv e Orde r No

. 1199 0 Protectio n o f Wetlands Executiv e Orde r No

. 1198 8 Floodplai n Managemen t 16USC§470e t

sea.. ; 4 0 CF R § 6.301(b);36CF R Par t 63, Par t 65 , Part 80 0 1 6 US C § 47 0

1 6 US C 46 9 4 0 CF R §6.301(c)

1 6 US C §461-46 7

1 6 US C §§470aa

4701 1
4 0 CF R § 6.302(a )
a n d Appendi x A

4 0 CF R § 6.30 2 & Appendi x A Y e s

N o

N o N o N o Y e s Y e s — N o Y e s Expand

s histori c preservatio n programs ; require s preservatio n o f resources include d i n o r eligible fo r listin g o n th e Nationa l Registe r fo r Histori c Place s (NRHP)

. Th e OU 5 EGW A Site s hav e bee n recommende d a s no t eligible fo r listin g o n th e NRH P an d ar e no t considere d contributing t o th e Leadville Histori c Minin g District

. Direct s federa l agencie s t o institut e procedure s t o ensur e tha t program s contribut e t o th e preservatio n an d enhancemen t o f non-federall y owne d histori c resources
. Consultatio n wit h ih e Advisor y Counci l o n Histori c Preservatio n is require d i f
remova l activitie s shoul d threate n cultura l resources
. Establishe s procedure s t o preserv e historica l an d archeologica l dat a tha t migh t b e destroye d throug h alteratio n o f terrai n a s a resul t o f a federa l constructio n projec t o r a federall y license d activit y program

. Preserve s fo r publi c us e histori c sites , buildings
, an d object s o f natura l significance

. Require s a permi t fo r an y excavatio n o r remova l o f archeologica l resources fro m publi c land s o r India n lands

. May b e relevan t an d appropriate i f archeologica l resources ar e encountere d durin g remedia l activities

. Minimize s advers e impact s o n area s designate d as wetlands

. Pertain s t o floodplai n managemen t an d constructio n o f impoundment s i n suc h areas
.

Pag e 1 o f 3TABL E 4 (continued ) SUMMAR Y O F POTENTIA L LOCATION-SPECIFI

C ARAR S O U 5 EGW A SITE S CALIFORNI A GULC H SUPERFUN D SIT E Standard

, Requirement

, Criteria

, o r Limitatio n Citatio n Potentiall y Applicabl e Potentiall

y Relevan t an d Appropriat e Descriptio n Sectio n 404 , Clea n Wate r A c t (CWA ) 3 3

US C 125 1 et seq.
. 3 3 CF R Par t 33 0 Y e s Regulate s discharg e o f dredge d o r fil l material s int o waters o f th e Unite d States

. Portion s o f th e OU 5 EGW A Site s ar e adjacen t t o water s o f th e U.S

. Substantiv e requirement s o f portion s o f Nationwide Permi t No

. 3 8 (Genera l an d Specifi c Conditions) ar e applicable t o OU 5 EGW A Site s remedia l activitie s conducte d withi n water s o f th e Unite d States

, althoug h none ar e anticipated

. Fis h an d Wildlif e Coordinatio n Ac t 1 6

US C §66 1 e t seq. ; 4 0 CF R § 6.30 2 N o N o Require s coordinatio n wit h federa l an d stat e agencie s t o provid e protectio n o f fis h
a n d wildlif e i n wate r resourc e developmen t programs ; regulate s action s tha t impound
, divert
, control
, o r modif y any bod y o f water

. However
, propose d remedia l actio n activitie s a t th e OU 5 EGW A Site s wil l no t affec t fis h o r wildlife

. I f i t appear s tha t remedia l activitie s ma y impac t wildlif e resources , EP A wil l coordinat e wit h bot h th e U.S

. Fis h an d Wildlif e Servic e an d th e Colorad o Departmen t o f Natura l Resources

. Endangere d Specie s Ac t 1 6 US C § 153 1 et seq..;50CF R §§20 0 an d 40 2 N

o N o Provide s protectio n fo r threatene d an d endangere d specie s an d thei r habitats

. However
, site-specifi c studie s di d no t documen t th e presenc e o f threatene d o r endangere d species

. I f threatene d o r endangere d specie s ar e encountere d durin g remedia l activitie s a t th e OU 5 EGW A Sites

, the n requirement s o f thi s Ac t woul d b e applicable

. Wildernes s Ac t 16US C

1311 ; 1 6 U S C 668 ; 5 0 CF R 53; 5 0 CF R 2 7 N o N o Limits activitie s withi n area s designate d a s wildernes s area s o r Nationa l Wildlif e Refug e Systems

. Remedia l activitie s planne d fo r OU 5 EGW A Site s wil l no t impac t any designate d areas
. Th e Ac t is , therefore
, no t a potentia l ARAR

. Resourc e Conservatio n a n d Recover y Ac t (RCRA)

, Subtitle D 4 0

CF R Par t 257 , Subpar t A
, §257.3- 1 Floodplains

, paragrap h (a ) N o N o Provide s genera l classificatio n criteri a fo r soli d wast e disposa l facilitie s pertainin g t o floodplains

. Remedia l activitie s planne d fo r OU 5 EGW A Site s will no t involv e establishmen t o f a soli d wast e disposa l facility

. STAT E O F COLORAD O Colorad o Historical
, Prehistorical

, an d Archaeologica l Resource s A c t C R S

§§24-80-40 1 t o 41 0 130 1 t o 1305 N

o Y e s Concern s

historical
, prehisiorical
, an d archaeologica l resources ; applie s onl y t o area s owne d b y th e Stat e o r it s politica l subdivisions

. May b e relevan t an d appropriat e i f remova l actio n impact s a n archaeologica l site

. Pag e 2 o f 3TABL E 4 (continued ) SUMMAR Y O F POTENTIA L LOCATION-SPECIFI

C ARAR S O U 5 EGW A SITE S CALIFORNI A GULC H SUPERFUN D SIT E Standard

, Requirement

, Criteria

, o r Limitatio n Citatio n Potentiall y Applicabl e Potentiall

y Relevan t an d Appropriat e Descriptio n Colorad o Registe r o f Histori c Place s CRS§ §

24-80.1-10 1 t o 10 8 N

o N o Authorize s

th e Stat e Historica l Societ y t o nominat e propertie s fo r inclusio n o n th e State Registe r o f Histori c Places

. Applicabl e onl y i f remova l actio n activitie s impac t a n are a liste d o n th e Register

. Nongame
, Endangere d o r Threatene d Specie s Ac t CRS§ §

33-2-10 1 to 10 8 N

o N o Standard

s fo r regulatio n o f nongam e wildlife an d threatene d an d endangere d species

. Site-specifi c studie s di d no t documen t th e presenc e o f threatene d o r endangere d species

. I f threatene d o r endangere d specie s ar e encountere d during remedia l activitie s a t th e OU 5 EGW A Sites

, the n requirement s o f th e Ac t wil l b e applicable

. Colorad o Specie s o f Specia l Concer n an d Specie s o f Undetermine d Statu s Colorad

o Divisio n o f Wildlif e Administrativ e Directiv e E-l

, 1985 , modifie d N

o N o Protect s specie s liste d o n th e Colorad o Divisio n o f Wildlif e generate d list

. Urge s coordinatio n wit h th e Divisio n o f Wildlif e i f wildlife specie s ar e t o b e impacted

. N o evidenc e o f specie s o f specia l concer n have been identifie d a t th e OU 5 EGW A Sites

. Colorad o Natura l Area s Colorad

o Revise d Statutes

, Titl e 3 3 Article 33, § 10 4 N o N o Maintain s

a lis t o f plan t specie s o f specia l concern
. Althoug h no t protecte d b y Stat e statue , coordinatio n wit h Divisio n o f Park s an d Outdoo r Recreatio n is recommende d i f activitie s wil l impac t liste d species

. Colorad o Soli d Waste Disposa l Site s an d Facilitie s Ac t 6

CC R 1007- 2 6 CC R 1007-2 , Par t 1 Y e s N

o Establishe s

regulation s fo r soli d wast e managemen t facilities
, includin g locatio n standards

. Non e o f th e propose d remedia l action s i n OU 5 will establis h a soli d wast e managemen t facility

. Selecte d portion s potentiall y applicable i f futur e activitie s establis h a soli d wast e managemen t facility

. Colorad o Nois e Abatemen t A c t C R S

§§25-12-10 1 t o 108 Y e s Establishe s maximu m permissibl e nois e level s fo r particula r tim e period s an d lan d us e relate d t o constructio n projects.________________________

_

Pag e 3 o f 3TABL E 5 SUMMAR Y O F POTENTIA L ACTION-SPECIFI

C ARAR S O U S EGW A SITE S CALIFORNI A GULCH SUPERFUN D SIT E Standard

, Requirement

, Criteria

, o r Limitatio n Citatio n Potentiall y Applicabl e Potentiall

y Relevan t an d Appropriat e Descriptio n FEDERA L Soli d Waste Disposa l Ac t
a s amende d b y the Resourc e Conservatio n a n d Recover y Ac t o f 1976 (RCRA ) Hazardou s Material s Transportatio n Ac t 4 0

CF R Par t 257 , Subpar t A : § 257.3

- 1 Floodplains

, paragrap h (a) ; § 257.3- 7 Air
, paragrap h (b ) 4 9 US C § 1801-181 3 4 9 CF R 107 , 171

- 17 7 Y e s

Y e s N

o Selecte d portion s o f Part 25 7 pertaining t o floodplain s an d ai r ar e applicable

. Thes e provision s establis h criteri a fo r classificatio n o f soli d wast e disposa l facilitie s an d practices

. Regulate s transportatio n o f hazardou s materials

. Woul d b e applicable i f futur e remedia l actio n a t th e OU 5 EGW A Site s involve d th e of f sit e disposa l o f flu e dust

. STAT E OF COLORAD O Colorad o Ai r Qualit y Contro l Ac t Colorad o Ai r Qualit y Contro l Ac t Colorad o Ai r Quality

. Contro l Ac t
Colorad o Soli d Wast e Disposa l Site s an d Facilitie s Ac t 5CC R

1001- 4 Regulatio n No

. 2 , Odors 5 CC R 1001- 5 Regulatio n No

. 3 , APEN s 5 CC R 1001-3 ; § lll.D.l.b.c.d

. § III.D.2.a,b,c,e,f,g

. Regulatio n No

. 1 6 CC R 1007- 2 Y e s

Y e s Y e s

N o —

—

Y e s Applicabl e

onl y i f remedia l actio n activitie s cause objectionabl e odors

. Remedia l actio n a t ih e OU 5 EGW A Site s i s no t expecte d t o produc e odors

. Substantiv e provision s o f APEN S wil l b e met

. Establishe s emission s contro l regulation s fo r constructio n o r modificatio n o f stationar y sources
. A n APE N wil l b e file d i f futur e remedia l action s distur b contaminate d soils

. Regulatio n No

. 1 provision s concernin g fugitiv e emission s fo r constructio n activities , storag e an d stockpiling activities , haul roads
, haul trucks
, an d tailin g pond s ar e applicable ( 5 CC R 1001-3 ; Section s III.D.2.a,b,c,e,f,g.)

.

Constructio n activitie s a t th e OU S EGW A Sites

, i f any , will b e conducte d i n accordanc e wit h a fugitiv e emission s dus t contro l plan

. Establishe s standard s fo r licensing
, locating
, constructing an d operating soli d wast e disposa l facilities

. Futur e remedia l activitie s planne d fo r OU S EGW A Site s m a y involv e th e disposa l o f soli d waste

.
Pag e 1 o f 2TABL E 5 (continued ) SUMMAR Y O F POTENTIA L ACTION-SPECIFI

C ARAR S O U 5 EGW A SITE S CALIFORNI A GULC H SUPERFUN D SIT E Standard

, Requirement

, Criteria

, o r Limitatio n Colorad o Wate r Qualit y Contro l Act
, Stor m Wate r Discharg e Regulation s Colorad o Mine d Land Reclamatio n Ac t

Colorad o Nois e Abatemen t Ac t Regulation s o n th e Collectio n o f Aquati c Lif e Citatio n
5 CC R 1002- 2 C R S 34-32-10 1 t o 125 ; Rul e 3 o f Minera l Rule s an d Regulation s C R S §§25-12-10 1 t o 10 8 2 CC R 406-8 , Ch

. 1 3 , Article III
, § 131 6 Potentiall

y Applicabl e Y e s N o

Y e s N o Potentiall

y Relevan t an d Appropriat e

— Y e s

— N o Descriptio n Establishe s requirement s fo r stor m wate r discharge s (excep t portion s relatin g t o Site-wide Surfac e an d Groundwater)

. Substantiv e requirement s fo r stor m wate r discharge s associate d wit h constructio n activitie s ar e applicable

. Regulate s al l aspect s o f lan d us e fo r mining , including th e locatio n o f minin g operation s an d relate d reclamatio n activitie s an d othe r environmenta l an d socio

economi c impacts

. Substantiv e requirement s o f portion s o f Rul e 3 regardin g Reclamatio n Measures
, Wate r - Genera l Requirement s (excep t portion s relatin g t o Site-wide Surfac e an d Groun d Water)
, Wildlife
, an d Revegetatio n ar e potentiall y relevan t an d appropriate

. . Establishe s maximu m permissibl e nois e level s fo r particula r tim e period s an d lan d u s e relate d t o constructio n projects

. Requirement s governin g th e collectio n o f aquati c lif e sample s fo r scientifi c purposes

. Remedia l actio n activitie s withi n th e OU 5 EGW A Site s wil l no t includ e biologica l monitoring

.

Pag e 2 o f 2TABL E 6 DETAILE D COS T ESTIMATE : ALTERNATIV

E 2 - INSTITUTIONA

L CONTROLS O U 5 EGW A SITE S CALIFORNI A GULC H SUPERFUN D SIT E Item/Descriptio n DIREC T CAPITA L COST S Institutiona l Control s Progra m Developmen t Progra m Implementatio n Quantit y

8 0 20 0 Uni t

h r h r Uni t Cos t

8 0 8 0 SUBTOTA L DIREC T CAPITA L COST S INDIREC T CAPITAL COST S Indirec t Capita l Cost s Administratio n Cost s Constructio n Managemen t Cost s Permi t Cost s 15 % 0 % 0 % SUBTOTAL INDIRECT CAPITAL COST S Capita l Cos t Contingenc y (Applie d t o bot h Direc t an d Indirec t Costs) 20 % TOTA L ESTIMATE D CAPITAL COST S ANNUA L OPERATIO N & MAINTENANC E

COST S Administrativ e Cost s 1 I s 2,50 0 Tota l

Cos t

$6.40 0 $16,00 0 $22,40 0

$3.360 $ 0 $ 0 $3,360 S7.84 0 $33,60 0
$2,50 0 TOTA L ANNUA L O& M COST S | | $2,50 0 FIV E YEA R REVIE W COST S Labo r - 1 Engineer s ($100/hr ) & 1 Technician s ($70/hr )
- 1 wee k @ 4 0 hrs/wk Trave l Per die m Laborator y Cost s Office/Administrativ e 4 0 2 2 0 2 0 m h

eac h mnd y eac h

m h 80.00 100.0 0 50.00 0.0 0 45.0 0 SUBTOTA L FIV E YEA R REVIE W COST S Fiv e Yea r Revie w Contingenc y 0.1 0 TOTA L FIV E YEA R REVIE W COST S $3,20 0 $20 0 $10 0 $ 0 $90 0 S4.40 0 $44 0 $4,84 0 TOTA L PRESEN T WORT H $85,49 6 ( 5 % rat e o f return

. 3 0 vea r period )TABLE ?

PRESEN T WORT H ANALYSIS

: ALTERNATIV

E 2 - INSTITUTIONA

L CONTROLS O U 5 EGW A SITE S CALIFORNI A GULC H SLPERFUN D SIT E
Yea r
0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 Capita l Cost s 533,60 0 O &

M Cost s

52.50 0 52,50 0 52.50 0 $2,50 0 57,34 0 52.50 0 52.50 0 52,50 0 52.50 0 57,34 0 52,50 0 52.50 0 52,50 0 52,50 0 57,34 0 52.50 0 52.50 0 52.50 0 52.50 0 57,34 0 52.50 0 S2.50 0 52.50 0 52.50 0 57.34 0 52.50 0 52,50 0 52,50 0 52,50 0 57,34 0 Tota l Annua l Expenditur e S33.60 0 S2.50 0 $2.50 0 $2.50 0 $2,50 0 57,34 0 $2.50 0 $2.50 0 52.50 0 52,50 0 57.34 0 52,50 0 $2,50 0 $2,50 0 $2,50 0 $7,34 0 $2,50 0 $2,50 0 52.50 0 52.50 0 $7,34 0 $2.50 0 $2,50 0 $2,50 0 52,50 0 57,34 0 52,50 0 $2.50 0 $2,50 0 $2,50 0 $7,34 0 TOTAL PRESEN T WORT H Rat

e o f Return = 3 % Discount Facto r 1.000 0 0.970 9 0.9426 0.915 1 0.8885 0.862 6 0.837 5 0.813 1 0.7894 0.766 4 0.744 1 0.722 4 0.701 4 0.681 0 0.661 1 0.6419 0.623 2 0.605 0 0.587 4 0.5703 0.553 7 0.537 5 0.521 9 0.506 7 0.491 9 0.477 6 0.463 7 0.450 2 0.4371 0.4243 0.412 0 Presen

t Wort h $33.60 0 52,42 7 $2,356 $2,28 8 $2,22 1 $6,33 2 S2.09 4 $2,03 3 $1,97 4 $1,91 6 $5,46 2 $1,80 6 $1,75 3 $1,70 2 $1,65 3 $4,71 1 $1,55 8 $1,51 3 $1,468 $1,42 6 $4,06 4 51.34 4 $1.30 5 $1,26 7 $1.23 0 i $3,50 6 $1,15 9 $1,12 5 $1,09 3 ! $1.06 1 $3,02 4 @3 % $100,470 Rat

e o f Retur n = 5 % Discoun t Facto r 1.000 0 0.9524 0.907 0 0.863 8 0.822 7 0.783 5 0.746 2 0.710 7 0.676 8 0.6446 0.613 9 0.584 7 0.556 8 0.530 3 0.5051 0.481 0 0.458 1 0.436 3 0.415 5 0.3957 0.376 9 0.358 9 0.341 8 0.325 6 0.310 1 0.295 3 0.281 2 0.267 8 0.255 1 0:242 9 0.231 4 Presen

t Wort h S33,60 0 $2.38 1 $2.26 8 $2.16 0 52,057 $5,75 1 51,86 6 $1,777 $1,69 2 $1.612 $4.506 51,46 2 $1,39 2 $1,32 6 $1,26 3 $3,53 1 $1,14 5 $1.09 1 $1.03 9 $98 9 $2,76 6 S89 7 $85 5 $81 4 $77 5 $2,16 8 $70 3 $67 0 $638 $60 7 $1,69 8 ©5 % $85,49 6 Rat

e o f Retur n = 10 % Discoun t Facto r 1.000 0 0.909 1 0.826 4 0.751 3 0.683 0 0.620 9 0.564 5 0.513 2 0.466 5 0.424 1 0.385 5 0.350 5 0.318 6 0.289 7 0.263 3 0.239 4 0.2176 0.1978 0.179 9 0.163 5 0.148 6 0.135 1 0.122 8 0.111 7 0.101 5 0.092 3 0.083 9 0.076 3 0.0693 0.0630 0.057 3 Presen t Wort h $33,60 0 $2.27 3 $2.06 6 $1.87 8 $1.70 8 $4.558 S1.41 1 $1,28 3 $1,16 6 51.06 0 52.83 0 S87 6 S79 7 572 4 $658 $1.75 7 $54 4 $495 S45 0 $40 9 $1.09 1 $33 8 $30 7 $27 9 $254 $67 7 521 0 519 1 $173 $15 8 $42 1 @ 10 % 564,64 1APPENDI X A RESPONSIVENES

S SUMMAR Y

### RESPONSIVENES S SUMMAR Y O U 5 EGVV A SITE S CALIFORNI A GULC H SUPERFUN D SIT E LEADVILLE

, COLORAD O

1. 0 OVERVIE W 

### T h e U.S

. Environmenta l Protectio n Agency (EPA ) ha s prepare d this Responsivenes s Summar y t o documen t an d respon d t o issue s an d comment s raise d b y th e publi c regardin g th e Propose d Pla n f o r th e Operabl e Uni t 5 (OU5 ) fo r Elgi n Smelter

, Grant/Unio n Smelter

, Wester n Zin c Smelte r an d 

### Arkansa s Valle y Sout h Hillsid e Sla g Pil e site s (collectivel y known a s th e "EGWA " sites ) o f th e Californi a Gulc h Superfun d Site

. EPA' s preferre d alternativ e an d th e remed y selecte d i n th e Record o f Decisio n (ROD ) involve s institutiona l controls
, whic h consist s o f measure s t o provid e informatio n t o curren t and/o r futur e lan d owner s regardin g th e environmenta l condition s a t th e 

### sit e throug h a zonin g "overla y district,"
, an d t o ensure tha t i f th e sit e i s develope d an y necessar y specia l precaution s o r requirement s ar e followed

. An y sampling o r respons e action s wil l be conducte d o r funde d b y ASARCO

, Inc.
, consisten t wit h th e developmen t plans

. A publi c meetin g 

### wa s hel d o n Augus t 1, 2000 at 7:00 p.m

. at the Minin g Hal l o f Fam e and Museu m i n Leadville

, Colorad o t o presen t th e preferre d alternativ e t o th e public

. Comment s wer e receive d durin g th e publi c comment period
, whic h wa s fro m Jul y 2 7 throug h Augus t 28 , 2000

. 

### Comment s receive d durin g th e publi c comment perio d an d EPA' s responses , ar e outline d i n thi s document

. B y law
, th e EP A an d th e Colorad o Departmen t o f Publi c Healt h an d Environmen t 

### (CDPHE ) mus t conside r publi c inpu t prio r t o makin g a fina l decisio n o n a cleanu p remedy

. Onc e publi c comment i s reviewe d an d considered
, th e fina l decisio n o n a cleanu p remed y i s documente d in th e ROD

. Thi s documen t include s th e followin g sections : 

### • Backgroun d

o n Recent Communit y Involvemen t 

### • Summary o f Publi c Comment s Receive d Durin g Publi c Commen t Perio d an d Agenc y Response s •

. Remainin g Concerns 2 . 0 BACKGROUN

D ON RECEN T COMMUNIT

Y INVOLVEMEN T T h e OU 5 EGW A Propose d Pla n wa s publishe d i n Jul y 200 0 an d describe s th e preferre d cleanu p 

### alternativ e fo r EGW A sites

. Based upo n consideratio n o f Nationa l Oi l an d Hazardou s Substance s 

### Pollutio n Contingenc y Pla n (NCP ) criteria , EP A determine d tha t Alternativ e 2 - Institutiona l Control s i s th e appropriate remed y fo r sla g an d non-residentia l an d residentia l are a soil s a t th e O U 5 EGW A sites

. A portio n o f th e publi c meetin g hel d o n Augus t 1 , 200 0 was dedicate d t o 

### acceptin g forma l oral comment s fro m th e public
, however
, n o ora l comment s wer e received

. Th e onl y writte n comment s receive d durin g th e publi c comment perio d wer e fro m th e CDPH E in a lette r date d Augus t 28 , 2000

.

A - l

### 3 . 0

SUMMAR Y OF PUBLI C COMMENT S RECEIVE D DURIN G PUBLI C COMMEN T PERIO D AN D AGENCY RESPONS E 

### T h e followin g writte n comment s wer e receive d fro m th e CDPH E durin g th e publi c comment period

. N o oral comment s wer e received

. Th e comment s ar e presente d in italicize d typ e an d th e response s ar e presente d i n regula r type

. N o

. 1 : As previously presented in draft Proposed Plan comments submitted to EPA dated JO/25/99, 

### 7/5/00, 7/11/00, and the CDPHE proposed Hot Spot Removal Plan, 3/28/00, since contamination has been identified above EPA 's action levels for reasonably anticipated uses, CDPHE believes that there are advantages to expeditiously removing the hot spots and 

### proceeding with immediate deletion of the EGWA sites. If the proposed Institutional Control Overlay (ICO) District is selected, it is not clear when these sites would be eligible for deletion. It should also be noted that the proposal for the use of the overlay district is currently in the developmental stage, making it impossible at this time for the state or public to provide meaningful comments on the adequacy of this approach. If EPA consistently applied this logic of deferring clean-up to sites nation-wide, contamination would simply remain in-place indefinitely awaiting development. This is clearly not the approach contemplated in the NCP and CERCLA (as discussed in our previous comments submitted by EPA). 

### Response : Unde r current lan d use, ther e i s n o unacceptabl e risk associate d wit h th e contaminatio n lef t in plac e a t th e EGW A smelte r sites

. I t i s possibl e tha t lan d us e coul d chang e fo r som e o f th e propertie s associate d wit h thes e sites

. Th e propose d institutiona l contro l overla y distric t woul d 

### insur e tha t an y futur e lan d us e wil l follo w an y necessar y precaution s o r requirement s associate d wit h th e wast e lef t in place

. Th e requirement s woul d includ e condition s tha t must be me t t o ensure protectivenes s an d ma y requir e additiona l sampling an d respons e action s consisten t wit h t h e futur e us e o r developmen t plans

. 

### E P A i s currentl y preparin g a n institutiona l contro l analysis an d design
, whic h include s th e propose d institutiona l contro l overla y district

. Thi s documen t wil l b e availabl e fo r publi c revie w 

### a n d comment

. I t i s anticipate d tha t onc e th e institutiona l contro l progra m i s in place
, thes e site s m ay b e delete d fro m th e Nationa l Prioritie s List

. Note tha t thi s approac h is consisten t wit h th e 

### institutiona l contro l overla y distric t propose d fo r Residentia l Soils withi n Operabl e Uni t 9 o f thi s Superfun d Sit e a s wel l a s othe r area s o f th e Sit e where wast e i s lef t in place

. E P A disagree s tha t removal o f thes e "ho t spots " offer s significan t advantage s ove r th e selecte d institutiona l contro l remedy

. Removal woul d b e limite d t o a dept h o f tw o fee t an d woul d stil l likel y requir e institutiona l control s t o ensur e tha t an y futur e developmen t remain s protectiv e o f human healt h an d th e environment

.

A- 2No

.

2 : 

### / i s no t clear ho w costs were determined. More explanation i s needed (such a s a n itemized breakout of capital costs and O&M activities) for what constitutes "capital costs" and what activities would be covered by O&M. Please clarify if developer or county costs for 

### sampling/analysis and review/approval activities have been determined and are included. Response : 

### A s shown o n Tabl e 7 , Detaile d Cos t Estimate : Alternativ e 2 - Institutiona l Controls

, o f th e OU 5 EGW A ROD

, direc t capita l cost s includ e progra m developmen t an d progra m implementatio n o f institutiona l controls

. Indirec t capita l cost s includ e administratio n costs , constructio n 

### managemen t costs , an d permit costs

. A contingency i s applie d t o bot h direc t an d indirec t capita l costs

. Th e operatio n an d maintenanc e (O&M ) cost s includ e annual administrativ e cost s an d fiv e year review costs , whic h include s labor
, travel
, pe r diem
, laboratory
, an d office/administrativ e 

### costs

. A contingency i s applie d t o th e fiv e yea r review costs

. ASARC O Inc

. (Asarco)
, th e responsibl e party , wil l b e responsibl e fo r any sampling
, laborator y analysis
, an d respons e costs

. EP A wil l review an d approv e an y respons e plans

. Th e samplin g an d 

### respons e cost s funde d b y Asarc o an d th e cos t fo r EPA' s review an d approva l effor t wer e no t include d in th e cost estimat e becaus e o f th e man y uncertaintie s associate d wit h thes e activities

.
4 . 0 REMAININ

G CONCERN S 

### Remainin g Concern s Based o n revie w o f th e writte n comment s receive d durin g th e publi c comment perio d (n o ora l 

### comment s wer e received)
, ther e ar e n o outstandin g issues associate d wit h implementatio n o f th e propose d remedia l action

.

A- 3