/PACIFI C W 1142161-R 8 SDM S

PACIFI C WESTER N TECHl5oLOGIE S LTD L1.9.f.?.yy:.fy.'.'?..^y.?-.L.?*?;..?.°?;.)V.h.?.?.lR!«!9?.C^^ ^

February 23 , 201 0 Unite d State s Environmenta l Protectio n Agenc y ATTN : Sta

n Christensen , WAM/CO R U S EP A Regio n 8 159 5 Wynkoo p Stree t Denver , Colorad o 80202-112 9 Subject : Californi a Gulc h Operabl e Uni t5

Arkansa s Valle y Smelter/Colorad o Zin c Lea d Mil l Sit e Fina l Remedia l Actio n Report , Revisio n 1 Wor k Assignmen tNo . 009-RARA-082 9 Contrac tNo . EP-W-06-00 6 Dea r Mr
. Christensen : Pacifi c Weste mTechnologies , Lt d (PWT ) i s please d t o provid e Revisio n 1 ofth e Final Remedia l Actio n (RA ) Repor t

for th e Califomi aGulc h Operabl e Uni t 5 , Arkansa s Valle y Smelter/Colorad o Zin c Lea d Mil l Site
. Thi s RA Repor t i s submitte d i n accordanc e wit h PWT' s Wor k Plan , date d Februar y 5 , 2009
. Revisio n 1 update d th e coordinate s o n Figur e 2 an d Appendi x C t o Colorad o Stat e Plan e coordinates , Centra l Zone
. Ifyo u hav e an y question s o r comment s regardin g thi s RA Report , pleas e cal l m e at (303 ) 274

- 540 0 x48
. Sincerely ,

Lev i Todd , P.E
. Califomi aGulc h 0U 5 AV/CZ L Sit e Projec t Manage r Pacifi c Weste mTechnologies , Ltd
. Attachmen t
cc : Jame s Bush , PW T Dou g Jamison , CDPH E Thoma s Roberts , PW T Fil e
www.pwt.co mFINA L REMEDIA L ACTIO N REPOR T

Revisio n 1
REMEDIA L ACTIO N CALIFORNI A GULC H - OPERABL E UNI T 5 ARKANSA S VALLE Y / COLARAD O ZIN C LEA D SITE S LAK E COUNTY , COLORAD O Prepare d for : 

# ^v /

U S Environmenta l Protectio n Agency , Regio n 8

159 5 Wynkoo p Street , Denver , C O 80202-112 9
Prepare d by :

^PACIFI C WESTER N TECHNOLOGIES , LTO , Pacifi c Wester n Technologies , Lt d 1104 9 W
. 44 * Avenue , Suit e 20 0 Whea t Ridge , C O 8003 3 U.S , EP A Contrac t

No
. Wor k Assignmen t

No
. Wor k Assignmen t

Name :
Date : EP-W-06-00 6 009-RARA-082 9 Californi aGulc h OU S (AV/CZ L Sites ) Februar y 23,201 0



### www.pwt.co m

### Tabl e o f Content s 1. 0 INTRODUCTIO

N / OPERABL

E UNI T BACKGROUN

D 1 2. 0 CONSTRUCTIO

N ACTIVITIES 2 2. 1 Historica

l Activitie s 2 2. 2 2009 Activitie s 2 2.2. 1 AVSit e 2 2.2. 2 CZ

L Sit e 3 2.2. 3 A V Consolidatio n Are aCove r 4 2.2. 4 Revegetatio n 5 3. 0 CHRONOLOG

Y O F EVENTS 5 4. 0 PERFORMANC

E STANDARD S AN

D CONTRUCTIO

N QUALIT

Y CONTRO

L 6 5. 0 FINA

L INSPECTIO

N AN D CERTIFICATION S 7 6. 0 OPERATIO

N & MAINTENANC

E ACTIVITE S 7 6. 1 Cove

r Syste mInspectio

n an d Maintenanc e 7 6. 2 Institutiona

l Control s 7 6. 3 Groundwate

r an d Surfac e Wate r Monitoring 8 7. 0 SUMMAR

Y O F PROJEC

T COST S 8 8. 0 FIVE-YEA

R REVIE W 8 9. 0 OBSERVATIONS AN D LESSONS LEARNE

D 8 10. 0 OPERABL

E UNI T CONTAC

T INFORMATIO

N 8 11. 0 REFERENCES 9
Table s Table 1 Figure s Figur e 1 Figur e 2 Figur e 3 Figur e 4 Figur e 5
APDendice s Appendix A Appendix B Appendix C Chronology of Events

Sit e Locatio n Ma p Fina l As-Buil t Surve y OU- 5 A V Excavation Areas CZ L Excavation Area s 200 9 Revegetation/Soi l Amendmen t Area s

Soi l Analytica

l Results Fina l Remedia l Actio n Inspectio n For

m Stampe d As-Buil t Surve y

R A repor t 009-RARA-082 9 Fina l re v 1 February 23 , 201 0 RA Report , Rev
. 1LIS T O F ACRONYM S AN D ABBREVIATION S

Asarc o Asarc o Incorporate d ARA R Applicabl e o r

relevan t an d appropriate requirements AV Arkansa s Valle y bg s Belo w groun d surfac e CDPHE Colorad o Departmen t o f Publi c Health an d Environmen t CERCL A Comprehensiv e Environmenta l Response , Compensation , an d Liabilit y Ac t COC s Contaminant s o f Conce m CQA P Constructio n Qualit y Assuranc e Pla

n CZ L Colorad o Zinc-Lea d EP A U.S
. Environmenta l Protectio n Agenc y HAS P Healt

h an d Safet

y Plan IC s Institutiona l control s MFG McCulley Fric k &Gihna n mg/kg Milligram s pe r kilogra m O& M Operatio n an d maintenanc e O U Operabl e Uni t Platinu mPlatinu mEnvironmental , LL C PM Projec t

manage r PW T Pacifi c Weste mTechnologies , Ltd
. R A Remedia l Actio n R D Remedia l Desig n RF E Residen t

fiel d enginee r RO D Recor d ofDecisio n RP M Remedia l Projec t Manage r SA L Soi l Actio n Level s SA P Samplin g an d Analysi s Plan SO W Statemen t o f Wor k TS P Tota l Suspende d Particulat e TTM M Tetr aTec h M M 

# D D D

D D

R A repor t009-RARA-082 9 Fina

l re v 1 1 1 Februar y 23 , 201 0 R A Report , Rev . 1 

# DU 1.

0 INTRODUCTIO N / OPERABLE UNI T BACKGROUN D
r- ] Leadville , Colorado , i s locate d i n aminera l ric h are aofth e Rock

y Mountain s wher

e copper , gold , silver , i lead , an

d zinc have bee

n mine d intermittentl

y sinc e 1859 , whe

n place r gold wa s discovered i

n Califomi a Gulch
. Du

e t o pas t mining , milling , an

d smeltin g activities , wast

e rock, tailings , slag , an

d smelte r wast e hav e bee n disperse d throughou

t th e community
. Previou s investigation s b y th e EP A an d other s indicat

e tha t minin g waste s hav

e adversel y affecte d groundwater , surfac e water , an d soil
. O n Septembe

r 8,1983 , EP A place d th e Califomi aGulc h Superfun d Site , comprised ofth e tow n o f Leadvill e an

d th e adjacen

t minin g district , o

n th e Nationa

l Prioritie s List
. Califomi aGulc h Operable Uni

t 5 (0U5 ) i s comprise

d of th e Arkansa s Valle

y Smelte r (AV ) an d Colorad o Zinc-Lea

d Mil l (CZL ) sites , a s well a s additiona

l site s throughou t th e Leadvill e area . The are ao f OU S consistin g ofth e A

V an d CZ L site s i s show

n o n Figur e 1
. 

# n 

# D

U Th

e Recor d ofDecisio n (ROD ) fo

r th e Califomi aGulc

h O U 5 AV/CZ

L Site s wa s signed i

n Septembe

r 2000
. The selecte d remed

y fo r th e OU S AV/CZ L site s i s excavation o

f contaminated soil s an

d tailings , n consolidatio n i

n a n on-sit e repositor y an d placemen

t of asoi l cove r ove r th e consolidate d material , an d [ J ancillar

y remedia l activities , suc

h a s demolitio n o f

selecte d stractures . Constractio n activitie s associated wit h th e selecte d remed

y consis t o f excavation an

d consolidatio n o f

flu e dus t int o a n on-site , [- 1 geomembrane-lined , full y encapsulated repository ; demolition t o grad e o f al l smelte r stracture s withi

n the I remediated area s except th e easternmos t

oftw o or e bins , th e bas e oftw o smokestacks , an d aconcret e arc h (th e Dewe y Arch) ; consolidation o f

tailings , non-residentia

l are asoils , an

d non-salvageabl e material s a t 

# O the A

V an d CZ L sites ; an d placemen

t ofa n 18-inc

h thick vegetated soi

l cove r ove r bot h th e flu e dus t repositor y an d th e consolidated tailing/non-residentia l soils
. Th e mai n contaminant s ofconce m(COCs ) a t the sit e ar e lea d an d arseni c i n soil an d tailings , and , a

t muc h highe r concentrations , i

n flu e dust
. Th e Remedia l Design (RD ) {Fina

l Remedia l Desig n Report , Arkansa s Valle y Smelte r an d Colorad o Zin

c Lea d ] Mil

l Sit e Operabl e Uni

t 5 , Califomi aGulc

h Superfun d Site ) wa s complete

d b y McCulley , Frick , an

d U Gilman , Inc
. (MFG ) (now Tetr

aTec h M M (TTMM) ) i

n April 200 5 fo

r Asarco , Incorporated (whic h becam e Asarco , LLC , hereafte

r collectively denoted simpl

y a s Asarco)
. U MFG, unde

r contrac t t o Asarco , conducted remedial activitie s a t th e sit e during th e 2004 , 2005,2006 , an d 200 7 constractio n seasons . A

t th e A V site , MF G excavated an

d consolidated approximatel y S O percen t of n the soil an

d tailing s contaminated wit

h lea d an d arseni c above commercial/industria l standard s (non

- {

_residentia

l standards) , constmcte d aflu e dus t repository , excavated an

d placed al l identified flu

e dus t withi n th e repository , an

d cappe d th e repository
. A

t th e CZ L site , MF G excavated an

d consolidated r- | approximatel

y 2,00 0 cubi c yard s o f

non-residentia

l contaminated tailings
. I

n addition , i

n 2007 , borro

w soi l fo r th e cove r to b e placed ove

r th e consolidate d contaminated soil an d tailin g wa s stockpiled o

n the site
. I Th

e descriptio n ofth e wor

k completed prio

r to th e involvemen

t of Pacifi c Weste mTechnologies , Ltd. , L^(PWT) is included in MFC's Construction Status Report, Operable Unit 5, Arkansas Valley Smelter and Colorad o Zinc-Lea

d Mil l Site , Califomi aGulc

h Superfun d Site , Leadville , Colorado , Decembe r 2006 ; r an

d i n atechnica

l memorandu

mfro mTTM M t o Asarco , LLC , dated Januar y 8 , 2008
. Th

e Januar y 200 8 U mem

o als o include s adescriptio n ofth e wor k needed to complet

e th e Remedia

l Actio n (RA)
. MF

G previousl y completed approximatel

y 5 0 percen

t ofth e RA
. J I

n 2009 , EP

A directe d PW

T t o complet e the R A a t th e Sit e unde r PWT' s RAC2 Contrac t

EP-W-06-006 , an d Wor k Assignmen

t 009-RARA-0829
. PWT' s Statemen t o f Wor k (SOW ) included updating th e R

D to r i reflec

t th e wor k conducted to dat

e an d remaining wor

k to b e completed , procuremen t ofth e I subcontractor , implementation ofth e RA , an d clos e ou t ofth e RA
. PW

T retaine d TTMM' s service s t o suppor t th e design efforts becaus e of thei r familiarit y an d experienc e wit

h the Site
. O

n Ma y 6 , 2009 , r- , PW

T issue d aReques t

fo r Proposa l to prospectiv e bidder s to complet e th e remaining R

A a t the Site
. O

n 

# U R

A repor t 009-RARA-082 9 Fina l re v 1 1 February 23 , 201 0 1 U RA Report , Rev
. 1

# D

Jun e 17 , 2009 , PW

T selected an

d awarde d th e remediatio n subcontract fo r implementin

g th e R A to the lo w bidder
. Platinu

mEnvironmental , LL

C (Platinum)
. 2. 0 CONSTRUCTIO

N ACTIVITIE S 2. 1 Historica

l Activitie s Asarco , through thei

r contracto r MFG , conducted remedia

l action s a t th e sit e during th e 200

4 throug h 2007 constractio n seasons . I n 2004 , demolitio n activities , primaril y associated wit

h th e weste

mor e bi n • - an d the Blas t Fumace/Or

e Hous e buildings , wer

e conducted
. I

n 2005 , th e flu

e dus t repositor y wa s constmcted , flu

e dus t wa s excavated an

d placed withi

n th e repository , a s wa s som e ofth e non-residentia

l T soil s i n the consolidatio n area , an d flue-dus t repositoi y monitorin g well s wer e installed
. I

n 2006 , the L contaminated tailing s fro

mth e CZ L sit e wer e excavated an

d consolidated i

n th e A V consolidatio n area . Durin g th e 2007 constractio n season , approximatel y 67,00 0 loos e cubi c yard s o f borro w soi

l fro mth e R Lak e Count y Airpor t borrow are awer

e hauled an

d stockpile d nea

r the cente r ofth e A V consolidation are a[ J o n to p of previousl y consolidate d soil an

d tailings
. Th

e Lak e Count y Airpor t borrow soi l ha

d bee n identifie d a s asuitabl e sourc e fo

r th e consolidatio n are acove r soil
. A description ofth e wor k completed n prio r t o PWT' s involvemen

t i s included i

n MFC' s Constructio n Statu s Report , Operabl e Uni t 5 , Arkansa s J Valle y Smelte r an d Colorad o Zinc-Lea

d Mil l Site , Califomi aGulc

h Superfun d Site , Leadville , Colorado , Decembe r 200 6 (MF G 2006) ; an

d u i atechnica

l memorandu

mfro mTTM M t o Asarc o date

d Januar y 8 , r- , 200 8 (TTM

M 2008)
. 2. 2 200 9 Activitie s Platinum , PWT' s R

A constractio n subcontractor , conducte d an d complete d constractio n activitie s durin g th e perio d fro

mJul y 6 , 2009 , throug

h Octobe r 23,2009
. Th

e R A constractio n i

n 200 9 wa s completed U using th e commercial/industria l us e standard s fo

r Soi l Actio n Level s (SALs ) fo

r the COC s lea

d an d arseni c tha t ha d bee n identified i

n MFC' s 200 5 R

D (MF G 2005)
. Thes e SAL

s ar e 6,500 milligram s pe

r f kilogra m(mg/kg ) fo

r lead , an d 65 0 mg/k

g fo r arsenic
. Th

e SALs identifie

d i n th e RO D fo r L commercial/industria

l us e wer e 6,100 to 7,70

0 mg/k g fo r lea d an d 61 0 to 69 0 mg/k

g fo r arsenic , an

d fo r recreationa

l us e th e RO

D SALs wer

e 16,00 0 mg/k g fo r lead , an d 1,40 0 t o 3,20 0 mg/k g arseni c (EP

A T 2000)
. Al l concentration s o f

COC s tha t wer e les s tha n th e SAL s use

d fo r th e 2009 constractio n activitie s |
_ wer e als o below th e lowe

r limi t ofth e rang e o f

commercial/industria

l us e SALs identified i

n th e ROD
. 2.2. 1 A V Sit e Afte r Asarco' s remedial activitie s i n 200 4 throug h 2007 , MF

G identifie d si x area s (Area s 1 , 2 , 3 , 4 , 5 an d 6 ) a t th e A V sit e a s remaining o

r potentiall y remainin g t o b e excavated
. Soi l i n Area s 1,5 , an

d 6 ha d p previousl y bee n excavated , bu

t additiona l confumator

y sampling neede

d t o b e conducted (MF

G 2006)
. Therefore, PWT

sampled and analyzed the soil

from these areas in accordance with the California Gulch Operabl e Uni

t 5 , Arkansa s Valle

y Smelte r cm d Colorad o Zin

c Lea d Site , Remedia

l Action , Construction |— , Qualit y Assuranc e Plan , (PW

T 2009b ) to determine i f

remediatio n woul

d b e required. Eac

h are awa s subdivided int

o approximatel

y one-half acr e decision area s a s necessary , an d fou r randomsubsample s o f soil , collecte d fro

mzer o to si x inche s i n depth , wer

e composite d fro

meac h decision area . Th

e sample s wer e analyzed fo

r lea d an d arseni c b y IC P analysis , using EP

A metho d 60 1 OB
. Concentration s o f lea d an d arseni c i n Area s 1,5 , an

d 6 wer e below SALs , s o n o additiona l remediatio

n activitie s wer

e conducte d ^ i n thes e area s (se e Appendi

x A fo r results)
. Base d o n previou s samplin

g result s conducted b

y MF G (MF G 2006) , an

d a s reflecte

d o n the 2009 U constractio n drawing s (PW

T 2009a) , Are a2 required excavatio n of aminimu m1.5-fee t of soil
. Are a3 required excavatio n of

aminimu m1 -foo t of soil , an d Are a4 require d excavatio n of aminimu mo f 2-fee t H o f soil
. Al l contaminated A

V soi l wa s excavated to th e design exten t an d nomina l depth , an d placed i n j J th e A V consolidation are aan

d grade d t o provid e positiv e drainage
. Post-excavation survey s indicate d tha t th e design excavation depth s wer e no t achieved i n limited or

isolated areas . However , i

t wa s decide

d p
R A repor t009-RARA-082 9 Fina

l re v 1 2 Februar y 23,201 0 R A Report , Rev . 1to conduc

t confirmator

y samplin g o n th e excavate d surfac e rathe r tha n conduc t "surgical " excavation
. I

f an y sample d are ashowe

d concentration s above SALs , the n furthe r excavation woul

d b e considered
. Afte r the initia l excavation activitie s ofth e A V sit e wer e completed
. Are a2 wa s split int o subarea s o f approximatel

y 0.5-acre s eac

h fo r confirmator

y sampling purpose s (Figur e 3)
. Confirmator

y samplin g an d analyse s wa s conducted i

n thes e subarea s i

n accordanc e wit

h th e Constractio n Qualit

y Assuranc e Pla

n (CQAP)
. One composit

e sample , comprised o f

4 subsample s collected fromth e uppe r six inches , wa s collected fromeac

h subare aan

d analyzed fo

r lea d an d arseni c (PW

T 2009b)
. Composit

e soi l sample s fo

r eac h of thes e area s demonstrated tha t COC s concentration s i

n th e remaining soil withi

n al l o f Are a2 wer

e below SALs
. Are a3 wa s als o split

int o subarea s of

approximately 0.5-acre s eac h fo r confirmator

y samplin g purpose s (Figur e 3)
. Concentration s of

arseni c i n subarea s 3 A , 3B , an

d 3 E wer e above SALs
. Subareas 3 A , 3B , an d 3 E wer e excavated b

y a n additiona

l 1. 5 feet
. Afte

r completion ofth e additiona l excavation , subarea s 3A , 3 B an d 3 E wer e resample d an d analyze d fo

r th e COCs
. Th

e concentration s o f

arseni c wer

e still highe r tha n th e SA L prescribe

d i n th e RO D fo r al l thre e subareas
. Base

d o n sit e knowledg e an

d th e suppositio n tha

t i t wa s likel y tha t th e contaminatio n extended deepe r tha n anothe r one foot, the U.S
. Environmenta

l Protection Agenc

y (EPA) Remedia

l Projec t Manage r (RPM ) directe d tha

t subarea s 3A , 3B , an d 3 E not b e excavated fiirther, bu

t rathe r backfilled wit

h borro w soil t

o aminimu

mdept h of six inches
. Thi s approac

h wa s implemente

d wit h th e understanding tha

t thes e subarea s d

o no t themselve s constitut e a n exposur e unit , an d tha t averag e lea

d an d arseni c concentration s a

t th e sit e ar e les s tha n the SALs
. Placemen

t o f backfil l i s a n additiona

l measur e tha t break s an y immediat

e an d localized exposur

e pathway
. Subare a3 E receive d anomina

l six inche s o f

soil cover , wherea s subarea s 3 A an d 3 B received a nomina l thicknes s o f

1 2 inche s o f

soi l cover . Thi s backfil

l wa s als o placed t

o ensur e positiv e drainag e of

f subarea s 3 B an

d 3E
. Afte r initia l excavation , samplin

g result s indicated tha

t concentration s o f

arseni c i n Are a4 wer

e above SALs
. Th e soi l i n Are a4 wa

s excavated b

y a n additiona

l tw o fee t an d resampled
. Are a4 resampling result s indicate d tha

t the concentration o f

arseni c wa s still above th e SAL
. Upo n directio n fromth e EP

A RPM , thi s are awa s als o backfille d wit h borro w soi l tha

t wa s aminimu

mtwo-fee t thick)
. 2.2. 2 CZ

L Sit e Thre e differen

t area s ofth e CZ

L sit e wer e addresse d a s par

t ofth e R A (Figur e 4) : (1 ) slop e area , (2 ) fluvia l tailing s area , an

d (3 ) the designed CZ

L consolidatio n area . Bot

h th e RO D an d MFC' s desig

n indicated tha

t additiona l samplin g shoul d b e conducted i

n th e slop e are at o mor

e clearl y defin e th e exten t o f contaminatio n (EP

A 2000 , MF

G 2006)
. A s a

n initia l samplin g screening effort , seve

n discree t sample s wer e collecte d fromth e surfac e ofth e slop e are aan d analyzed fo

r lea d an d arsenic
. Onl

y on e discree t sampl e ha d concentration s o

f eithe r lea d or arseni c tha

t exceeded SALs ; howeve

r result s fromsevera

l othe r sample s wer

e clos e to the SALs
. Based o n thos e results , th e CZ

L slop e are awa s divided int o nomina l 0.5-acr e subareas , consisten

t wit h th e siz e ofth e sampl

e subarea s previousl

y establishe d an

d use d a t th e sit e i n 200 5 - 2007 , an

d adjuste d t o includ

e simila r vegetatio n o

r disturbanc e condition s withi n a subare a(se e Figur

e 4)
. Fo r example , th e od

d shap e fo r CZL-E3 wa s partiall

y drive n b y th e fac t tha t thi s shap e comprised a

n are atha t wa s vegetate d a

t th e time of

sampling
. I

n accordanc e wit

h th e CQA P (PW T 2009b) , composit

e sample s wer

e collecte d fromthes e subareas , eac h composit

e comprising generall

y fou r subsample s (projec t

record s provid

e detaile d sampling information ) collected fromth e to p si

x inche s of th e surface , an

d analyze d fo r lea d an d arseni c b y ICP analysis , EP

A method 60 1 OB
. Th

e samplin g result s indicate d tha

t concentration s o

f lea d exceeded SAL s i

n subarea s CZL-W2 , CZL-W5 , CZL-E2 , an d CZL

E6
. Contaminate d CZ

L soil i n thes e fou

r subarea s wa s excavated to the exten t show n o n Figur e 4 , an d t o anomina l dept h o f on e foot
. Upo

n directio n fromth e EP

A RPM , th e excavated soil wa s place d i n th e A V consolidatio n area .

R A repor t009-RARA-082 9 Fina

l re v I 3 Februar y 23 , 201 0 R A Report, Rev . 1Durin

g implementation ofth e R

A i n th e summe

r o f 2009 , th e CZ

L consolidatio n are awa s eliminated fromthe design an

d th e R A b y th e EP A RPM
. Thi s wa s possibl e an d appropriat e because :

• Th

e sampling results indicated tha t soil s fromonl

y par t ofth e CZ L slop e wer

e contaminated , whic

h greatl y reduced th e volum

e o f CZ L soil s tha t required consolidation

• Excavation o f

contaminated A

V soil s an d placemen

t i n th e A V consolidation are aha

d progressed t

o th e poin t wher e i t wa s recognized tha

t placemen t of CZ L soil s i n th e A V consolidatio n are acoul

d b e accommodated ther

e withou t materiall y affectin g th e desig n o r implementatio

n

• Subsurfac e tailing s still presen t i n th e CZ L consolidatio n are acould b e excavated an d consolidate d a

t the A V site , thereb y eliminating or reducing apotentia

l sourc e of meta l loading to Califomi aGulc

h

• Elimination ofth e CZ L consolidatio n are aeliminated contaminated soil s frombeing consolidate d adjacen

t to , an d within th e historica

l flood plai n o f Califomi aGulch
.



# D Afte r completion ofth e 2009 excavation activities , confirmator y sampling wa

s conducted i

n accordanc e wit h the CQA P (PW T 2009b)
. Result s ar

e presente d i

n Appendi x A
. Confirmator

y samplin g result s indicated tha

t concentration s o f

lea d i n th e "bench " are a(comprised ofth e uppe r part s o f CZL-E2 , CZL

E6 , CZL-W

S an d CZL-W6 , a s show

n o n Figur e 4 ) wer e above SALs
. Upo

n directio n fromth e EP

A RPM , thi s are awa s als o backfilled wit h borro w soi l to aminimu

mthicknes s of

one foot
. Thi s approac

h wa s implemente

d wit h th e understanding tha

t th e benc h are adoe s no t

itself constitut e a n exposur e unit , an d tha t averag e lea

d an d arseni c concentration s a

t th e sit e ar e les s tha n th e SALs
. Placemen

t o f backfil l i s a n additiona

l measur e tha t breaks an y immediat

e an d localized exposur

e pathway
. Al

l area s disturbed i n the CZ L slop e durin g th e 2009 constractio n activitie s wer e surveyed afte

r excavation
. A s provided b

y th e design , an

d a t the directio n ofth e EP

A RPM , soil s fromth e fluvia l tailing s are a (Figur e 4 ) wer e als o excavated an

d placed i n th e A V consolidation area . Tailing s an d othe r residua l evidenc e o f

tailing s wer

e presen t i n th e fluvia

l tailing s area , including visua l impacts , suc

h as lac k o f vegetation
. Thi s excavation wa s conducted i n orde r t o remove visuall

y impacte d soi l tha t wa s suspected of being asourc e o f

meta l loading t o Califomi aGulch
. Therefore , confirmator y samplin g ofthi s are awa

s not conducted
. Visually-eviden

t tailing s fromthe CZ

L "consolidatio n area " wer

e excavated upo

n directio n fromth e EP

A RPM
. Thes e tailing s wer

e presen t a t adept h of approximatel

y 2 t o 3 fee

t belo w groun d surface (bgs ) an

d extended to adept

h of approximatel

y 3 to 6 fee

t bgs , wit h th e dept h being greate

r to th e west

an d shallowe r t o th e east . A six-inc

h thick cla y zone wa s observed beneat h som e ofth e tailings , whic

h migh t hav e bee n evidenc e tha

t th e historica

l tailing s are aha

d bee n lined
. Th

e excavated soil wa s place

d i n the ^

J A V consolidatio n area . Th

e CZ L consolidatio n are awa s backfilled wit h borrow soil an

d grade d to provid e positiv e drainag e int

o th e Califomi aGulc

h channel
.
— 2. 2 J AV Consolidation Are a Cover Afte r completion ofth e excavation activities , th e A V consolidatio n are awa

s covered wit

h aminimu

mo f 1 8 inche s of

screene d cove

r soil
. Th e cove r soil wa s fromone oftw o sources , eithe r Lak e Count y L unscreene d borro w soi l tha

t wa s stockpiled o

n th e cove r during Asarc o activities , o

r borrow pi t soi l (se e Figur e 2)
. Bot h type s of borro w soi

l wer e screened suc

h tha t no particl e siz e greate

r tha n 3 inche s i

n n diamete r wa s allowed fo

r th e cove r soil
. Th e cove r soil wa s placed using excavators , dozers , an d | J scrapers . The eastemhalf

o f th e southe mboundar y ofth e A V consolidation cove

r wa s grade d wit h a3: 1 (horizonta l t o vertical ) slop e wit

h adiversion ber

ma t th e to p ofth e slope
. Thi s ber mi s intende

d to direct r
R A repor t009-RARA-082 9 Fina

l re v 1 4 Februai y 23 , 201 0 R A Report , Rev . 1 I

### u 

## n stormwate

r shee t flo w fromth e uppe

r eas t sid e ofth e cove

r int o acontro l swale tha

t drain s th e sout h easte mquadran t ofth e cove

r (Figur e 2)
. The sit

e wa s grade d i

n accordanc e t o th e design t o ensur e adequat e drainag e an

d preven t soi l erosio n (2 % minimu

mslope , 3: 1 maximu

mslope)
. T o preven t stormwate

r fromentering th e A

V consolidatio n are aan

d to collec t

stormwate r runnin g of f th e cover , aperimete

r stormwate

r ranon/ranoff

ditc h wa s installed
. Al

l area s disturbed i

n th e 200 4 throug h 200 9 constractio n activitie s wer e graded t o ensur

e positiv e drainage
. 2.2. 4 Revegetatio n Upo n completio n o f

grading activities , th e A

V an d CZ L site s wer

e ripped an

d tille d fo r revegetation
. Approximatel

y twent y sample s wer

e collecte d a

t variou s location s fo

r agronomi c characteristic s t

o provid e dat ause d i n th e evaluation o f

whethe r compos t additio n o r p H mitigation of

soil s wa s necessar y a s par t of revegetatio n activities
. Soi l wa s analyzed fo

r th e following : p H electrica l conductivit

y sodiu mabsorptio n rati o catio n exchang e capacit

y Lim e estimat e (qualitative ) or

(calciu mcarbonat

e equivalency ) organi c matte

r nitrate-nitroge

n phosphora s potassiu m magnesiu m zin c iro n manganes e coppe r boro n sulfate-sulfu

r textur e estimate s fertilize r suggestion s fo

r agricultural , horticultura

l o r reclamation applications
. Th e concentration s o

f organi c carbo

n wer e typically on e percen

t o r greater , whic

h ar e sufficien t t o suppor t revegetation withou

t addition o f

compost . The value s o f

p H wer e typicall y les s tha n 5 , excep t fo r th e borro w soi l (neutra

l pH) , o r i n area s wher

e borro w soil ha

d alread y bee n placed
. Numerou s soil area s exhibite d low p

H value s unsuitable fo

r revegetation
. I

t wa s determined tha

t significan t cos t saving s coul

d b e realize d b

y utilizin g exces s borro w soi l rather tha n lim e fo r amendin g th e lo w pH-value soils
. Therefore , screened borrow soi l wa s placed i n area s containin g low p

H soil s t o th e exten t tha t borrow soi

l wa s available
. A minimu

mof 6 inche s of

screened borro w soil wa s placed i n th e area s show

n i n Figur e 5
. Are a2 a t th e A V sit e wa s th e onl

y are awher

e lim e wa s added
. Pelletized lim e wa s adde d an d tille d int o the soi l i n Are a2 a t arat e o f 3 0 ton s pe r acr e The sit e wa s fertilized wit

h 24:4:1 2 (nifrogen:phosphate:potash) slow releas e fertilize r a t arat e o f 10 0 pound s pe

r acre . Th e cove r an d excavate d area s wer

e revegetated i

n accordanc e wit

h th e RD
. 3. 0 CHRONOLOG Y O F EVENT S Table 1 present s th e chronolog y of event s a t the OU- 5 site
.

R A repor t009-RARA-082 9 Fina

l re v 1 Februar y 23,201 0 R A Report , Rev . 1Tabl e 1 - Chronolog y o f Event s Dat e Septembe r 2000 200 4 Apri l 200 5 2004-200 7 Jun e 19,200 9 July 200 9 Octobe r 23,200 9 Januar y 201 0 Even t Recor d ofDecisio n signe d fo

r Operable Uni

t 5 AV/CZ L Sites , Califomi aGulch Superfim d Sit e Asarc o conducte d demolitio n activitie s a t the sit e MF G remedia

l desig n approve d - Fina

l Remedia

l Desig n Report , Arkansa s Valle

y Smelte r an d Colorad o Zinc-Lea

d Mil l Sit e Operable Unit 5 , Califomi aGulch Superfun d Sit e Asarc o conducte d remedia l action s a

t the sit e (se e narrative ) 200 9 PW T desig n approved

- Califomi aGulc h Operable Uni

t 5 , Arkansa s Valle

y Smelte r an d Colorad o Zin c Lea d Site , Remedia

l Action , Constmctio n Packag e (PW T 2009a ) 200 9 remedia

l actio n constmctio n mobilizatio n Fina l Inspection , site remedia l actio n field wor

k completed Fina l Remedia

l Actio n Repor

t 

# D

4. 0 PERFORMANC

E STANDARD S AN

D CONTRUCTIO

N QUALIT

Y CONTRO

L Approximatel

y 4 1 acre s of

lan d wa s remediated a

t th e A V sit e an d approximatel

y fou r acre s of lan d wa s remediate d a

t the CZ L area . Al l excavated contaminated soi l wa s place d i n th e 14-acr

e A V consolidation are a(Figur

e 2)
. Th e overal l goa l ofth e project

wa s to cleanu

p OU S AV/CZ L site s t o a t o r belo w the SAL s prescribe d i

n th e ROD
. Upo

n completio n ofth e prescribe d remed y i n th e constractio n documents , confirmator

y soi l samplin g fo r th e COC s wa s conducted
. Th e soi l i n th e excavated area s me

t SALs afte r initia l an d additiona

l excavation , i

f necessaiy , wit

h mino r exceptions
. Concentration s of arseni c i n soil i n fou r area s remained above actio n levels
. Al l fou r area s ar e located i n th e A V site : Are a3A , Area3B , Are a3E , an

d Are a4 (Figur

e 3)
. Subarea s 3 A & 3 B wer e backfilled wit

h aminimu

mof 1 2 inche s o f borro w soil , subare a3 E wa s backfille d wit h aminimu

mo f 6 inche s o f borro w soil , an d Are a4 wa s backfilled wit

h aminimu

mo f 2 fee t of borro w soil , a s directe d b

y th e EP A RPM
. Averag e concentration s ofth e COC s fo r th e entir e A V sit e ar e below th e SALs fo

r the COCs
. Environmenta

l samplin g an d analysi s wa s conducted i

n accordanc e wit

h EP A guideline s an

d the CQA P (PW T 2009b)
. Soi

l sampl e result s fo r bot h th e A V an d CZ L area s ar e include d i n Appendi x A
. Real

time air monitoring fo

r tota l suspende d particulate s (TSP) wa s conducted dail y using aMiniRAM® durin g constractio n activities
. Ai r monitoring result s neve

r exceeded actio

n levels
. Al

l samplin g method s an

d datawer e verifie d an d 2 0 percen t wer e validated
. Excavatio n o

n sit e wa s performanc e based
. A V an d CZ L area s ha d t o b e excavated t

o differen t depth s pe r th e constractio n drawings
. Th e residen t field enginee

r (RFE) field-verified excavation depths
. I n addition , pre - an

d post-excavatio n survey s wer e conducted o

n th e individua

l areas . Surve

y dat awer e independentl

y reviewed b

y PWT' s project

enginee r to verif y soi l depths
. Th

e A V consolidated are awa s field-verified b

y th e RFE , an

d surve y dat awa s verified b

y PWT' s projec

t enginee r to ensur e tha t final gradin g provided positiv e drainage
. Th e final cove

r ofth e A V consolation are arequire d positiv e drainag e an d a n 18-inc h thick cove r o f screene d borrow soil
. Cove r soil particl e siz e wa s field-verified throughou t th e screening proces s b

y the RFE
. Soi l dept h thicknes s o

n th e cove r wa s confirme

d o n sit e b y th e RF E an d confirme d b y PWT' s
R A repor t009-RARA-082 9 Fina

l re v 1 Februar y 23 , 201 0 R A Report , Rev . 1projec t

enginee r base d o n pre - an d pos t

constractio n survey s preforme d b y th e subcontractor
. Density testin g (AST M D-292 2 an d AST M D-698 ) wa s performe d o n th e place d cove r soi l at afrequency o f every 1.5 acre s b y th e Remediatio n Subcontractor , an d wimesse d b y th e RFE
. Al l densit y test s result s wer e abov e th e require d density requirements
. Th e contro l swale , ditches , an d drainag e stracture s wer e constructe d pe r

th e constractio n documents
. Al l wate r diversio n feature material s an d gradin g wa s verifie d b y RFE
. 5. 0 FINA L EVSPECTIO N AN D CERTIFICATION S Informal prefina l inspection s wer e conducte d o n al l area s a s excavatio n an d othe r constractio n activitie s wer e complete d in individua l subareas
. Punch-lis t item s identifie d a s par

t o f thes e prefinal inspection s wer e addresse d a s constractio n progressed
. A final sit e inspectio n wa s complete d o n Octobe r 23 , 2009
. Th e EP A RPM , PWT' s projec t manage r (PM) , RFE , an d th e remediatio n subcontracto r wer e presen t

for th e final inspection
. A t

th e tim e ofth e final inspectio n n o item s wer e foun d tha t require d resolution
. EP A accepte d th e wor k a s complete
. Th e Remedia l Actio n Inspectio n for mi s presente d in Appendi x B
. Healt h an d safet

y wa s amajo r

conce mfo r

th e project
. PWT , th e remediatio n subcontractor , al l othe r subconfractors , an d al l othe r personne l wer e require d t o follo w th e provision s in thei r respectiv e HASP s (o n file at PWT)
. Durin g th e 200 9 constractio n activitie s n o health an d safet y incidents , los t

tim e accidents , o r

near-misse s wer e recorded
. 6. 0 OPERATIO N & MAINTENANC E ACTIVITE S Thi s sectio n present s abrie f outlin e o f

recommendation s fo r

long-ter moperatio n an d maintenanc e (O&M ) ofth e remedy , includin g cover-syste minspectio n an d maintenance , non-cove r remediatio n are a inspectio n an d maintenance , surface-drainag e confrol s inspectio n an d maintenance , an d groundwate r monitorin g an d institutiona l control s (ICs)
. Recommendation s fo

r O& M fo r th e consolidatio n are aar e summarize d i n Sectio n 6. 1 below
. However , th e non-cove r area s tha t were remediated a s apar

t ofth e remedial actio n fo

r OU S projec t shoul d als o b e inspected
. Th e run-o n an d run-of

f contro l feature s associate d wit h th e A V and CZ L site s shoul d b e inspecte d periodically
. Visua l inspectio n shoul d b e conducte d o f al l drainag e ditches , berms , chutes , swales , channels , and culvert s t o verif y operation , capacity , an d th e effectivenes s o f erosio n contro l measures . 6. 1 Cove r Syste m Inspectio n an d Maintenanc e Th e primar

y exposure-pathwa

y barrier for th e AV consolidatio n site i s a n 18-inch soi l cover . I

n addition , flue dus t material s ar e containe d withi n afull y encapsulate d geomembran e liner , covere d b y betwee n 4 an d 8 fee t o f nonresidentia l are asoils , an d th e fina l 18-inc h clea n soi l cover . Th e boundar y ofth e repositor y i s represente d b y th e flue dus t monument s a s show n o n Figur e 2
. Th e soi l cove r shoul d b e inspecte d fo r

indication s o f

excessiv e differentia

l settlement , erosion , cracking , sloughing , ponding , o r othe r potentia l problem s tha t

ma y affec t th e integrit

y o r performanc e ofth e cove r system . Th e succes s o f vegetatio n effort s shoul d als o b e assessed
. 6. 2 Institutiona l Control s Th e RO D require s implementatio n o f IC s a s acomponen t

ofth e remedy t o provid e notificatio n tha t abarrie r i s in place , an d t o restrict

lan d us e t o protec t

th e integrit

y ofth e remedy i

n th e cover

area s (EPA 2000)
. I

t i s understoo d that

th e EPA , Colorad o Departmen t o f Publi c Health an d Environmen t (CDPHE ) and Lak

e Count y Commissioner s ar e workin g t o develo p IC s for th e Califomi aGulch OU S AV/CZL sites
. RA report 009-RARA-082 9 Fina l re v 1 7 Februar y 23 , 201 0 R A Report , Rev
. 1

# D

6.3 Groundwater an

d Surfac e Water Monitoring A n elemen t ofth e RO D remedy i s t

o establis h along-ter

mmonitoring progra

mt o asses s th e qualit

y o f surface wate

r an d groundwate

r followin g implementation ofth e remed y (EP A 2000)
. Three groundwate r well s (on e upgradien

t an d tw o downgradien

t ofth e repository) wer

e installed b

y MF G an d extende d b y PW T (Figur e 2)
. Groundwate

r an d surfac e wate

r fo r th e overall Califomi aGulc

h Superfun d site s wer e include d within aseparat

e operabl e unit , 0U12
. An

y groundwate

r an d surfac e wate

r monitoring requirement s fo

r OU S shoul d b e integrated wit

h monitoring requirement s fo r OUl2
. 7. 0 SUMMAR

Y O F PROJECT COST S Th e RO D identifie d the estimate

d remedy capita

l cost of approximatel

y $2.8 5 million
. Wor

k performe d i n 2009 unde r th e PW T contrac t wa s approximatel

y $1. 5 million
. Th

e cos t fo r R A wor k performe d i n previou s years b y Asarc o i s no

t publi c information
. 8. 0 FIVE-YEAR REVIE W Becaus e the contaminated tailings , flue dust , an d non-residentia

l are asoil s wil

l remai n o n site , th e Selected Remed

y require s afive-year

revie w unde r Section 12 1 o f

CERCLA , an

d Sectio n 300.430(f)(4)(ii ) ofth e Nationa l Contingency Plan
. Th

e five-year

revie w include s areview ofth e groundwate

r an d surfac e wate

r monitoring dataan

d a n evaluatio n a s t

o ho w wel l th e Selecte

d Remed y i s '- ' achieving th e R

A objective s an

d applicabl e or

relevan t an d appropriat

e requirement s (ARARs ) tha t i t wa s designed to meet . 9. 0 OBSERVATION

S AN D LESSON

S LEARNE

D Th e presenc e o f

previousl y stockpile d borro w soil o n top o f previousl y consolidate

d contaminate

d soi l an d withi n the consolidatio

n are acreate

d placemen

t issue s fo r the additiona

l contaminate

d soi l tha t neede d t o b e place d withi n the consolidatio

n area , surve

y issue s to properl

y documen t th e to p ofth e consolidate

d soi l surfac e an d thicknes s of

soi l cover ; an d logistica l issue s wit h respect t o sequencin

g o f consolidation , cove

r placement, an

d surveying
. Whe

n wor k i s conducte

d a t aprojec t ove r multipl e years , i t i s importan

t t o conside r ho w curren t actions , whic

h ma y nee d to b e take

n immediatel

y becaus e of

schedul e constraints , affec t th e overal l pla n fo r executio n ofth e wor

k thoug h completio

n ofth e project
. 10. 0 OPERABL

E UNI T CONTAC

T INFORMATIO

N

• Sta n Christensen , EP

A RPM
. U S EP A Regio n EPR-S R 1595 Wynkoo

p Stree t Denve r C O 80202-112 9 Christensen.Stanley@epa.go v (303 ) 312-669 4 phon e (303)312-715 1 fa

x

• Lev i Todd , P.E. , Projec

t Manage r Pacifi c Weste

mTechnologies , Ltd
. 1104 9 Wes t 44 * Avenu

e Suit e 20 0 Whea t Ridg e C O 8003 3 LTodd@pwt.co

m (303 ) 274-540 0 x4 8 phon

e

R A repor t009-RARA-082 9 Fina

l re v 1 8 Februai y 23 , 201 0 R A Report , Rev . 1(303 ) 274-616 0 fa x

• Ric k Anacleto , Remediatio n Subconfracto r Platinu mEnvironmental , LL C 40 1 Wes t Count y Road 1 6 Lovelan d CO , 8053 7 (970)-669-227 7 phon e (970)-669-238 2 fa

x 

### 11. 0 REFERENCE S MFG , Inc
. 2005
. Fina l Remedia l Desig n Report , Arkansa s Valle y Smelte r an d Colorado , Zinc-Lea d Mil l Site , Californi aGulc h Superfun d Site
. April
. MFG , Inc
. 2006
. Constructio n Statu s Report , Operabl e Uni t 5 , Arkansa s Valle

y Smelte r an d Colorad o Zinc-Lea d Mil l Sit e Califomi aGulc h Superfun d Site , Leadville , Colorado
. December
. Pacifi c Weste mTechnologies , Ltd
. (PWT)
. 2009a
. Californi aGulc h Operabl e Uni t 5 , Arkansa s Valle

y Smelte r an d Colorad o Zinc-Lea d Mil l Site , Remedia l Action , Constructio n Package
. June
. Pacifi c Weste mTechnologies , Ltd
. (PWT)
. 2009b
. Califomi aGulc h Operabl e Uni t 5 , Arkansa s Valle

y Smelte r an d Colorad o Zinc-Lea d Mil l Site , Remedia l Action , Constructio n Quality Assuranc e Plan
. July
. Tetra Tech. (TT), January 8,2008. Technical Memorandum to Asarco, LLC. California Gulch Superfund Site, OUS

- A V Smelter Site and CZL Mill 2008 Construction Activities. U.S
. Environmenta l Protectio n Agenc y (EPA)
. 2000
. Recor d o f Decisio n - Operabl e Uni t 5 , A V/CZ

L Sites , Californi aGulc h Superfun d Site , Leadville , Colorado
. September
.

R A report 009-RARA-082 9 Fina

l re v 1 9 Februar y 23 , 201 0 R A Report , Rev
. 1

## r Figure s

n

u



## U r

R

A repor t009-RARA-082 9 Fina

l re v 1 Februar y 23 , 201 0 R A Report , Rev . 1h APPROXIMAT E ALIFORNI A GULC H r ^ OUS . AV/CZ L v

BOUNDAR Y / ' 

# ] 200 0 f t

] /TACIRCWESTERNTECHNOLOGES.LTD . 1104 9 Wes

t 44t h Avenue , Suit

e 20 0 Whea t Ridge , C

O 8003 3 303-274-540 0 WWW.PWT.CO M 

# SIT E LOCATIO N MA P CALIFORNI A GULC H OPERABL E UNI T 5 AV/CZ L SITE S LEADVILLE , C O FIGUR E 1 NO . I BY IDATEibtefct^lPTIOT T PROJECT : Californi a Gulc h OU S 0 ^ B^TGNE D BY : I-12-2Q 1 APPR6VE D BY : 201 C


# n LLEGEND:

2009 DESIGN

EXCAVATION

AREAS 2009 DESIGN

AREA NOTATION CONFIRMATORY

SAMPLING DESIGNATION ASARCO

EXCAVATION

AREAS

PRIOR TO 2009 CONSTRUCTION ACTIVITIES

NOT REQUIRING ADDITIONALEXCAVATION 5 

## ® * CONCENTRATIONS OF ARSENIC

IN THESE DESIGNATED

AREAS EXCEEDED

THE SOILACTION

LEVELS

AT THE FINALEXCAVATION DEPTH. THESE

AREAS WERE BACKFILLED

WITH BORROW

SOILTO

A DEPTH

OF 6 TO 24 INCHES.

/PACIFI C WESTER N TECHNOLOGIES , LTO . 1104 9 Wes

t 44t h Avenue , Suit e 20 0 Wtiea t Ridge , C

O 8003 3 303-274-540 0 WWW.PWT.CO M 

## A V EXCAVATIO N AREA S CALIFORNI A GULC H OPERABL E UNI T 5 AV/CZ L SITE S LEADVILLE , C O NO

. B Y I DAT E I DESCRIPTIO N PROJECT : Californi a Gulc h OU S DATE : DESIGNE D BY : 1-12-201 0 APPROVE D BY : JM B j j m 20 0 f t

FIGUR E 3APPROXIMAT E CALIFORNI A GULC H OUS , AV/CZ L BOUNDAR Y

/ 

# y / LEGEHD: EXCAVATED

FLUVIALTAILING

AREA EXCAVATED

TAILINGS

AREA EXCAVATED

SLOPE AREA SAMPLING

AREA BOUNDARY SAMPLIN G ARE

A DES/GNATIO N EXCAVATION CRITERIA: SAL VISUALTAILINGS VISUALTAILINGS

CZL-E 1



# N NOTE : SOI L I N SAMPLIN G AREA S CZL-W2 , CZL-W5 , CZL-E 2 AN D CZL-E 6 CONTAINE D CONCENTRATION S O F COC s ABOV E SALs

. EXCAVATIO N I N THES E AREA S WER E FIEL D FI T AROUN D EXISTIN G MIL L STRUCTURES

. EXCAVATIO N I N CZL-E 3 OCCURRE D A S A RESUL T O F PUSHIN G CONTAMINATE D SOI L FRO M CZL-E 6 DOWNSLOPE

.

1104 9 WM t 44tt i AMiHit . Sult

a 20 0 WhMtRMo* . C

O 8003 3 303-274-640

0 WWW.PVIT.CO

M 

# CZ L EXCAVATIO N AREA S 200 9 CALIFORNI A GULC H OPERABL E UNI T 5 AV/CZ L SITE S LEADVILLE , CO NO

. I B Y I DAT E I DESCRIPTTO

N PROJECT : Californi a Gulc h OU S DATE : DESIGNE D BY : 1-12-201 0 APPROVE D BY : TW R 

### JM 10 0 f t

FIGUR E 4BORROW AREAS

LEGEND: NO REVEGETATION AREA WITH

A MINIMUM

6" SOIL BACKFILL& STANDARD SEED MIX AREA WITH

NO SOILAMENDMENT & STANDARD

SEED MIX AREA WITH

LIME SOILTREATMENT & STANDARD

SEED MIX AREA WITH

A MINUMUM

6" SOIL BACKFILL& DITCH

SEED MIX AREA WITH

SOILBACKFILL& DITCH SEED MIX AREA WITH

A MINIMUM

6" SOIL BACKFILL& WETLAND MIX OVERSIZED

ROCK AREA ^ii'^.)i:-y.ii

1104 0 WM t 44l h AvMwa . Suttt 20 0 WhMtRMga . C O 8003 3 303-274440 0 WWW.PWr.CO M 

# REVEGETATION/SOI L

AMENDMEN T AREA

S CALIFORNI A GULC H OPERABL E UNI T 5 AV/CZ L SITE S LEADVILLE . CO NO. I B Y IDATEIDESCRIPTRU R PROJECT : Californi a Gulc h OU S PATE ; DESIGNE D BY : 1-12-201 0 APPROVE D BY : J3/ff i



### Am 30 0 f t

FIGUR E 5

### Appendi x A Soi l Analytica l Result s

RA report 009-RARA-082 9 Fina l re v 1 February 23 , 201 0 R A Report , Rev
. 1

### Arkansa s Valle y Sit e - Soi l Analytica l Result s Pre-Excavatio n A V Are a Sampl e I D AV I AV 1-0 2 AV5 E AV5 W AV 6 Dat e Sample d

7/9/200 9 7/9/200 9 7/10/200 9 7/10/200 9 7/10/200 9 Arseni c

44 8 34 1 20 4 45. 9 36. 8 Lea d

5,83 0 5,02 0 2,51 0 12 8 20 5 Post-Excavatio n A V Are a Sampl e I D AV 4 AV 4 AV2 A AV 2A-0 2 AV2 B A V 2B-0 2 AV2 C AV2 D AV2 E AV2 F AV2 G AV2 H AV2 I AV2 J AV2 K AV3 A AV3 A AV3 B AV3 B AV3 C AV3 D AV3 E AV 3 E-0 2 AV3 E BORRO W 1 BORRO W 2 Dat e Sample d

8/17/200 9 9/15/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/18/200 9 8/27/200 9 9/3/200 9 8/27/200 9 9/15/200 9 8/27/200 9 8/27/200 9 8/27/200 9 8/27/200 9 9/15/200 9 8/27/200 9 8/27/200 9 Arseni c

1,30 0 77 0 4.8 6 3.5 5 12. 8 15. 2 4.0 1 6.9 4 26. 8 11 6 9.5 4 11 2 33. 3 10 0 3 0 2,01 0 1,46 0 1,570 1, 1 7 0 49 1 25 7 2,02 0 2,10 0 42 8 18 2 11 3 Lea d

N D 24 9 81. 7 5 8 15 0 22 1 32. 8 • 52. 5 27 9 33 0 28 4 1,33 0 10 4 1,03 0 15 2 1,090 18 3 76 7 13 7 13 1 72. 9 31 0 38 6 99. 2 1,18 0 62 1 Notes : 1
. Se e Figur e 3 fro msamplin g area s 2
. Eac h sampl e generall y wa s acomposit e o f fou r subsample s for

mth e samplin g area . Specifi c subsampl e location s are in th e projec t files. 3
. Al l sample s ar e expresse d i n mg/kg 4
. All item s identifie d in re d ar e abov e Soi l Actio n Level s

Pag e 1 o f 1

### Colorad o Zin c Lea d Sit e - Soi l Analytica l Result s Pre-Excavatio n CZ L Are a - Discree tScreenin g Sample s Sampl e I D CZL l CZ L 2 CZ L 3 CZ L 4 CZ L 5 CZ L 6 CZ L 7 Dat e Sample d

7/9/200 9 7/9/200 9 7/9/200 9 7/9/200 9 7/9/200 9 7/9/200 9 7/9/200 9 Arseni c

30. 2 62 1 22. 3 8 6 160 27 4 86. 6 Lea d

1,73 0 9,67 0 62 4 1,18 0 5,60 0 6,18 0 1,19 0 Pre-Excavatio n CZ L Are a - Co m Sampl e I D CZ L E- 1 CZ L E- 2 CZ L E-3 CZ L E- 4 CZ L E-5 CZ L E- 6 CZ L W- 1 CZ L W-1-0 2 CZ L W- 2 CZ L W-3 CZ L W- 4 CZ L W-5 CZ L W- 6 Dat e Sample d

8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 8/3/200 9 posit e Sample s

Arseni c 80. 3 15 2 64. 1 5 3 30. 8 13 5 129 160 14 5 25 7 125 23. 5 85. 2 Lea d

3,75 0 10,90 0 1,34 0 1,55 0 4,59 0 7.55 0 4,63 0 5,72 0 8.22 0 5,46 0 2,78 0 14,40 0 4,23 0 Post-Excavatio n CZ L Are a Sampl e I D CZ L S-B CZ L Slope- E CZ L Slope- W Dat e Sample d

9/1/200 9 9/8/200 9 9/8/200 9 Arseni c

93. 3 33. 8 26. 4 Lea d

H.\W 1,12 0 1,24 0 Notes : 1
. Se e Figur e 4 fromsamplin g area s

2
. Eac h sampl e generall y wa s acomposit e o f fou r subsample s for

mth e samplin g area . Specifi c subsampl e location s ar e in th e projec t files. 3
. Al l sample s ar e expresse d i n mg/k g 4
. Al l item s identifie d in re d ar e abov e Soi l Actio n Levels
. 5
. CZ L S-B i s asampl e collecte d fro mth e benc h ofth e CZ L slope
.

Pag e 1 o f 1

### Appendi x B Fina l Remedia l Actio n Inspectio n For m 

# D n u 

# n

n



# n L n

R A repor t 009-RARA-082 9 Fina l re v 1 February 23 , 201 0 RA Report , Rev
. 1

# n
U

n CtaUfomi a Guic h OV 5 Arkansa s Vallcy/Colonido,2%i 6 Lea d Sits s

Lai n Covniy * Colond o 

### Fina l RaniMilai Aciio n Inspectio n bGtDlier.23,20a 9 AiElMl y ftiinpllniawl analywsit f Atfaniw^vaMwiiibaw M 15, 6 Excavatio n o f AVsubaraa s odntaMniKGoiioenftratip m o f faa d brarrani c •nwla r tJw n sctft

w teweb Ramad M Actio n J Canmhiad ? Ye s Ye s Cpnllnnator

y wmpHngan d aiialwesir f AVsufaea s t S i and 4 Ad»BtlonalwgawattirfcfiWsiifcWBM.9iind> r ConsoHdattenofeMBwaiBdAVaoBliiconwiMatlonaie a

Stwenftit t ofMocfcplled cewaol l 

### Hacamenta f ttrliich aoii ^ Ye s 

### ve s Ye s Ye s 

### ConnnictionofteimandiHwIeonco w Gonstructto n o f A

V iMnminterninoq/ifund f contro l inteii , Includin g InttallalioniBftwfDadMeft s SaiamllB t antf-anahieesaf'Ca.ilop e Ye s Ye s ve s Ye s Buavatlo n o f GE

L subaraa

s containin g eoheentfttlon s o f (aa d o r anenlfriTBalierthi n actio n tewh ConflrnBaterywmpHn g en d analwe s o f WBawatrtiCa . area s AtfWonal^vaBonofCaa.wdiaieBS '

- Ekcawatlo

n o f catamns s are a base d o n visua l obserwatton s Ye

s Ye s Ye s BackBI I o f ca.talBni s aw e t o ftcilltala dralneg a AironbmlcsainpllBgefAVandClLeiea s Mitigation

of low pH aoAs by Ome amendnieht

or placemiint

of 6-Inch lift of bonow soil ., Ye s Ve s



### L Rev^talio n o f A

V an d O L area s iHsturiia d durin g 200 9 an d previou s

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v imri c •bo w ictloi n tavais Wi s taft t h plic e II I M M 4an d portto m o f Aie a 9 at a dept

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f irarfe w MIltmialaaitflmiatlonareaplhofaallcBMrwasMaHlMrnaairanlplHestaeai ^ rMfMibil i Iwfn a andift w p!|pm« ^ aii d sehedi*fe r oampMbi g tfniafvrriMunNiy. Sol i eoiitalpln g laa

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PW T Platlnun i

### Appendi x C Stampe d As-Buil tSurve y

R A repor t 009-RARA-0829 Fina

l re v 1 Februar y 23 , 201 0 

## n h R A Report , Rev
. 1a . 

# I

o o c n 

# I