Apache Tailin g Impoundments Operable Unit 7 Proposed Plan

Public Meeting January 25, 2000

PRESENTATION PACKET

Prepared by:

Asarco Incorporated

130 West 9

th

 Street 495 East 51

st

 Ave.

Leadville, CO 80461 Denver, CO 80216

M ASAfiCO

consultin g

scientist s and

engineers
Color Map

T he followin g map contains

color that does not appear on

scanned image.
• Denver Georgetown

DENVER AND RIO GRANOE WESTERN

CANTERBUR Y TUNNE L

J

LEADVILL E DRAINAG E TUNNE L

Evens Gulch

Stra y Horse Gulch Storr Ditch OU7-APACJ^E TAILING S

Y / K TUNNE L

CALIFORNI A GULC H

CALIFORNIA GULCH . SUPERFUN D SIT E BOUNDAR YN

ASARCO O U7 - APACHE TAILINGS

FIGURE 1-1 GENERA L SIT E LOCATION MAP

PROJECT: 5344.4 DATE : SEPTEMBER 1999 B Y : SCG I CHECKED : DL L MFC, Inc .

consulting scientists and engineers
RI/F S PROCES S FOR OPERABL E UNIT 7

Superfun d Listin g

1983

Site-Wide Remedial Investigation s (Rl )

1991-1993

Consent Decree

1994

i

Draf t Feasibilit y Stud y

1996

Supplemental Investigatio n & Evaluation , Interim Rl & FS Submittal s

1997-1999

Removal Action s

1997 & 1999

Final Focused Feasibilit y Stud y

2000

Proposed Plan/Publi c Comment

2000

Record of Decision (ROD)

2000

Remedial Action

2000-2001 ASAfiCO
Site Description Tailin g Impoundment s

• Four distinct tailing impoundments

• Main Impoundment:

11.3 acres

- 630,000 cy

maximum thickness of 50 ft

• North Impoundment:

1.8 acres

- 14,500 cy

maximum thickness of 12.5 ft

• Tailin g Ponds 2 and 3:

2.0 acres total

- 41,200cy

- 6 to 14 ft thick ASARCO
Site Description (cont.)

Surface Water

• California Gulch channel below Main Impoundment tailing via two 24-inch claytile culverts

• Wooden box culvert drains upgradient

surface water

• Starr Ditch conveys runoff from Stray Horse Gulch and east Leadville

Groundwater

• Pore water within tailing

• Alluvial aquifer - in unconsolidated

sedimentary deposits beneath

impoundments

• Bedrock aquifer - in consolidated bedrock

• Numerous springs in area

ASAfiCO
Color Map

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color that does not appear on

scanned image.
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EXPLANATION

SURFACE WATER SAUPt l LOCATION

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UINI-REZOUETER

PIEZOUETER LOCATION

ASARCO O U7 - APACHE TAILINGS

SIT E MAP OPERABLE UNIT 7 APACH E TAILING S IMPOUNDMEN T

PROJECT: 5344.4 REV: DATE : JANUAR Y 2000 B Y : JMK | CHECKE

MFC, Inc.

consulting scientists and engineers
Summary of Remedial Investigations

Objective - evaluate the nature and

extent of contamination

Characterization of sources,

groundwater, and surface water

1

 Activities:

groundwater sampling/analysis

groundwater level monitoring

geotechnical testing

surface water sampling/analysis

geochemical testing/analysis

pond water sampling/analysis

rainfall-runof f sampling/analysis

1

 Surface water and groundwater mass

loading analyses to identify sources ASARCO
RI Summary

Main Impoundment (MI):

acid-generating at and near surface

acid-neutralizing at base

North Impoundment (NI) :

highly acid-generating tailing

high infiltration

Tailin g Ponds Nos. 2 and 3 (TP2/3)

highly acid-generating tailing

removed in 1997

Groundwater loading mechanisms:

runoff from MI embankments

percolation through TP2/3

percolation through NI tailing

ASARCO
RI Summary

Surface Water

• Flow/loads vary seasonally and

yearly

• Loads predominantly from

upstream inflows

• Loading from springs

downgradient of TP2/3

decreased substantially after

tailing removal in 1997

ASflfiCO
Removal Actions

1997-1999

1997

• Removed Tailin g Pond Nos . 2 and 3

• Backfilled/regraded excavation areas

• Regraded unstable area and placed

rock protection along toe of SW

slope of Main Impoundment

1999

• Regrading/placement of pre-load fill

on southern portion of Main Impoundment

• Installed wick drains in pre-load fill

area

• Placed fill over North Impoundment

ASARCO
Remedial Action Ob j ectives

Control airborne transport of

tailing particles

Control erosion of tailing materials and deposition into

local water courses

Control leaching and migration

of metals from tailing into

surface water

Control leaching and migration

of metals from tailing into

groundwater ASARCO
Cultural Resources

Considerations

T wo resources (sites) evaluated:

Apache Mill/Tailin g Pile

Possible stamp mill

Mill/tailin g ineligible and noncontributing Stamp mill is potentially eligible for

nomination to the NHRP, but is not

contributing as a landscape feature

Data recovery plan submitted to SHP O

Implement Data Recovery Plan and

perform mitigation, if necessary,

prior to disturbance ASARCO
Remedial Action

Alternatives

• #1: No Action

• #2A: Simple Soi l Cover

• #2B: #2A + Groundwater Controls

• #2C: #2A with Alt. Channel Alignment

> #3A: Soi l Cover with Geosynthetic Barrier

• #3B: #3 A + Groundwater Controls

• #3C: #3 A with Alt. Channel Alignment

• #4A: Removal/On-Site Consolidation

• #4B: Removal/Placement in Repository

> Preferred Alternative ASffiG O
Alternative #1

No Action

No further cleanup or

remediation

No action provides a baseline

for comparison of other

alternatives

ASARCO
Alternative #2A

Simple Soil Cover

> Regrade impoundment surface and

embankment

> Excavate channel for California Gulch to carry 500-year flood event

> Create a single combined tailing area

• Place 18" cover soil over 6" coarse

sand and 12" compacted tailings

> Revegetate capped surface

> Construct run-on diversion ditches

> Evaluate effectivenes s via

monitoring program

> Common to all in-place closure alternatives

ASAfiCO
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ALTERNATIV E 3 : MULTI-LAYE R COVER SECTION

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ALTERNATIV E 2 : SIMPL E SOI L COVER SECTION

NOTE :

1. THI S DRAWIN G I S NOT T O SCALE . APACH E TAILING S IMPOUNDMEN T

ALTERNATIVE COVER SECTION S

PROJECT: 5344.4 REV: DATE : SEPTEMBER 1999 B Y : CAA | CHECKED : FL C MFC, Inc.

consulting scientists and engineers
Color Map

T he followin g map contains

color that does not appear on

scanned image.
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POND NO. 2

APCROXIWATE LOCA Of RE-CONSTRUCTED 500-YEAR CALIFORNIA

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SURFAC E WATER SAMPL E LOCATION

GROUNOWATER MONITORING WEL L

SOIL BORING

MINI-PIEZOMETE R

PIEZOMETER LOCATION

A

-iPAVED ROAD

GRAVEL ROAD

WATER

BUILDING/STRUCTUR E

POWER POLE

ASARCO APACH E TAIUNG S IMPOUNDMEN T

ALTERNATIVES 2A, 2B, 3A, & 3B: REGRADING PLAN

PROJECT: 5344.4 REV: DATE : JANUARY 2000 B Y : JMK | CHECKED 

MFG , Inc.

consulting scientists and engineers
TEMPORAR Y HAUL ROAD

TEMPORARY HAUL ROAD S.:.:;:

GUUCH TAILIN G IMPOUNDMEN T

ASARCO O U 7 - APACHE TAILING S

COVER SOIL BORROW AREA

PROJECT: 5344.4 DATE : JANUAR Y 2000 B Y : JMK j CHECKED : MFG , Inc .

consulting scientists and engineers
Alternatives #2B & 2C

•2B: Simple Soil Cover with Groundwater Controls

• Same as Alternative #2A, with

addition of groundwater controls

• Instal l trench drain immediately

downgradient of Main Impoundment

•2C: Simple Soil Cover with Channel Alignment

• Same as Alternative #2A, with

alternate channel alignment

• Construct channel to convey

California Gulch farther to the north

ASAfiCO
Plo t time: 12:30 pm Plo t dote: 01-21-2000 JMK D:\5344\5344-283.dwg 01-20-2000 01:44 pm

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ALTERNATIV E 2A/3A ALTERNATIV E 2C/3C

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ASARCO O U 7 - APACHE TAILING S

CHANNE L ALIGNMEN T

2A/3A VS. 2C/3C

PROJECT: 5344.4 REV:

DATE : JANUAR Y 2000 B Y : JMK I CHECKED : MFC, Inc.

consulting scientists and engineers
Alternative #3A

Soil Cover with Geosynthetic Barrier

Same as Alternative #2A,

except multi-layer cover instead

of simple soil cover

Construct multi-layer cover

system, with 18" cover soil over

geotextile drainage net and

geosynthetic barrier

ASWCO
Alternatives #3B & 3C

•3B: Soil Cover with Geosynthetic Barrier with Groundwater Controls

• Same as Alternative #3A, with

addition of groundwater controls

• Instal l trench drain immediately

downgradient of Main Impoundment

•3C: Soil Cover with Geosynthetic Barrier with Channel Alignment

• Same as Alternative #3 A, with

alternate channel alignment

• Construct channel to convey

California Gulch farther to the north

ASARCO
Alternative #4A

Removal and On-Site Consolidation

• Completely remove tailing material

from Main and North Impoundments

• Transport material to on-site

consolidation area at the Hecla (Malta Gulch) Tailin g Impoundments (prepare areas first)

• Cap consolidation area with simple

soil cover

• Regrade excavation area and/or

place import material, as needed

• Revegetate consolidation site and

removal area

ASAROO
Alternative #4B

Removal and Disposal in On-Site Repository

Completely remove tailing material

from Main and North Impoundments

Develop new repository in upper Oregon Gulch, along with haul roads

and runon/runoff controls

Transport material to new repository

C ap repository with multi-layer

cover

Revegetate repository and removal

areas

ASflfiCO
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ALTERNATIV E 4A : POTENTIA L ROUTES T O MALTA GULCH

ALTERNATIV E 4B : POTENTIA L ROUTES T O OREGON GULCH

APPROXIMAT E LOCATION O F MINERA L BEL T BIK E TRAI L

ASARCO O U 7 - APACHE TAILING S

POTENTIAL TRANSPORT ROUTES TO

CONSOLIDATION AN D REPOSITOR Y SITES

PROJECT: 5344.4 DATE : JANUARY 2000 REV: B Y : JMK | CHECKED 

MFC, Inc .

consulting scientists and engineers
Evaluation Criteria

Overall protection of human health

and the environment

Compliance with ARARs

Long-term effectivenes s and

permanence

Reduction of toxicity, mobility., or

volume through treatment

Short-term effectivenes s

Implementability Cost

State acceptance

Community acceptance

ASARCO
TABL E 7-1 Summar y of Comparative Analysi s of Remedial Alternative s OU7- Apache Tailings

evaluation Criterion Dverall protection

of human health and

t he environment

"ompliance

wilt i

ARARs

.XMig-lerm

effectiveness and

permanence

deduction of

toxicity , mobility ,

or volume

Sliort-lurm

effectivenes s

niplcmcn labilit y

Cost

State

acceptance *

Community

acceptance *

No Action Alternative #1

N ol protective of human

health and the

environment Does not comply with

ARARs

No long-term decrease

in loading to groundwater

Minimal reduction (16%)

of mobility. No reduction

of toxicity or volume No short-term reduction

in risk

Readily implementable

$0

Simpl e Soi l Cover

Alon e Alternative #2A

Protective, would meet

RAOs for impounded tailin g

Would comply with ARARs

Very good long-term

effectiveness and

permanence Mobilit y reduced by 88%. No reduction of toxicity

or volume Moderate short-term

effectivenes s due to

risk during regrading

Good to moderate

mptemen lability,

excavation and access

considerations

$3,641.883

With Groundwater Controls Alternative #2B

Protective, would meet

RAOs for impounded tailin g

Would comply with ARARs

Very good long-term

effectiveness and

permanence Mobility reduced by 88%. No reduction of toxicity

or volume Moderate short-term

effectiveness due to

risk during regrading

Moderate technical

implementability ;

difficul t trenching

due to large depth

13,973,383

Alternate Channel Alignmen t

Alternative #2C Protective, would meet

RAOs for impounded tailin g

Would comply with ARARs

Good long-term

effectiveness and

perm an en co Mobility reduced by 88%. No reduction of toxicity

or volume

Low short-term

effectiveness due to

risk during regrading

and working with wet

tailing

Moderate to low

implementability , due to

difficultie s excavating

and working with large

volume of wet tailings.

$4,127,057

Mult i Layer Cover

Alon e Alternative #3 A

Protective, would meet

RAOs for impounded tailin g

Would comply with ARARs

Very good long-term

effectiveness and

permanence Mobilit y reduced by 96%. No reduction of toxicity

or volume Moderate short-term

effectiveness due to

risk during regrading

Good to moderate

implementability ,

excavation and access

considerations

$4.077.736

With Groundwater Control s Alternative #3 B

Protective, would meet

RAOs for impounded tailin g

Would comply with ARARs

Very good long-term

effectiveness and

permanence Mobilit y reduced by 96%. No reduction of toxicity

or volume Moderate short-term

effectiveness due to

risk during regrading

Moderate technical

mplementability ;

difficul t trenching

due to large depth

$4,409.236

Alternate Channel Alignmen t

Alternative #3C Protective, would meet

RAOs for impounded tailin g

Would comply with ARARs

Good long-term

effectiveness and

permanence Mobilit y reduced by 96%. No reduction of toxicity

or volume

Low short-term

effectivenes s due to

risk during regrading

and working with wet

tailin g

Moderate to low

mplementability , due to

difficultie s excavating

and working with large

volume of wet tailings.

$4,562,910

Removal

With On-site Consolidatio n Alternative #4A

Protective, would meet

RAOs for impounded tailin g

Would comply with ARARs

Very good long-term

effectiveness and

permanence Mobilit y reduced by 96%. No reduction of toxicit y

or volume

Low short-term

effectiveness due to risk

during removal and

transport, higher potential

T or releases and increased

duration Difficulties associated with

arge volume, excavation/

water handling, and

development of

consolidation site

$12,060.100

Deposit in On-site Repository

Alternative M4B

Protective, would meet

RAOs for impounded tailin g

Would comply with ARARs

Very good long-term

effectiveness and

permanence Mobilit y reduced by 96%. No reduction of toxicity

or volume

Low short-term

effectivenes s due to risk

during removal and

transport, higher potential

for releases and increased

duration Difficulties associated with

arge volume, excavation/

water handling, and

developmen t of

repository site

$13,177.200

NOTES : Alternative #1: No Action (beyond removal of Tailin g Ponds Nos. 2 and 3) Alternative W2A: Cover soil + 6" drainage layer + 12" compacted tailings over tailings Alternative #2B: Alternative #2A plus graundwaler controls Alternative #2C: Alternative #2A with alternate channel alignment for California Gulch

Alternative //3A: Cover soil + drainage net + geosynthelic clay liner over tailings Alternative #3B: Alternative #3A plus groundwater controls Alternative #3C: Alternative #3A with alternate channel alignment for California Gulch

Alternative W4A: Removal and on-site consolidation Alternative #4B: Removal and disposal in an on-site repository

* Those criteria will be evaluated after the public comment period.

J:\5344\5344-4\FS\TAB7-1 .WB2 Page 1 of 1 MFG . Inc.
Proposed Plan

Alternative #3A

Soil Cover with

Geosynthetic Barrier

flSflfiCO
Alternative #3A - Proposed Plan

Provides overall protection of human

health and the environment

Achieves RAOs

Complies with ARARs

Provides permanence and long-term

effectivenes s

Can be implemented with standard

technologies

Reduces existing metal loading to

surface water and groundwater

Eliminates risk to terrestrial

ecosystem ASARCO
Cost Summary

Alternative #3A

• Estimated Capital Costs

$2,504,000

• Annual O&M Costs

$85,000

• Five-Year Review Costs

$41,500

• Total Present Worth

$4,078,000

ASARCO
OU7 Schedule of Work

Initiate construction in 2000

Anticipated completion in

2001

ASARCO