Community Meeting Presenting Engineering Design for Saginaw Hill Remediation

1
Community Meeting Presenting Engineering Design
for Saginaw Hill Remediation

• Presented by
• ecology and environment, inc.
• On behalf of
• Bureau of Land Management
• October 25, 2007

2
Goals of Presentation

• Brief Overview of Site History and Previous
  Studies
• Brief Summary of EE/CA Report
• Presentation of Engineering Design
• Discussion of Phased Implementation
• Community Involvement
• Next Steps How BLM Will Move Forward

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Site History Overview
4
Site Location
0
1000
Joseph Ave.
Harriet Johnson Elementary School
Valencia Road
5
Mining and Smelting Processes and the
Wastes Created

• Two Processes took place from the late 1800s to
  mid-1900s
• Mining for mineral compounds took place at both
  Saginaw and Palo Verde Mines.
• Smelting, or extracting metal from ore by
  melting, was performed at the Saginaw Mine only.
• Waste Material Left Behind
• Waste rock rock that is not ore (does not
  contain economic metal), but was extracted to
  access the ore
• Slag waste material from the chemical actions
  of smelter operations
• Tailings fine grained remains of ore generated
  during processing

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Investigations and Remediation Efforts
------Without clear authority to apply CERCLA
further investigations were dormant------
In 2001 Pima County submitted an application
to acquire the land under the Recreation
and Public Purposes Act (remediation required)
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The EE/CA Report
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Summary of EE/CA Results

• Engineering Evaluation/Cost Analysis
• Identify the problem (Site Characterization)
• Conduct an evaluation of the risk to public
  health and the environment (Risk Assessment)
• Identify the objectives of the alternatives
  (Removal Action Objectives)
• Identify Alternatives and Evaluate (Alternative
  Development) and
• Select an Alternative (Recommended Removal
  Action).

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Site Characterization Results
WP 2
Saginaw

• Auxiliary Waste Piles and Sediment in Arroyo

Palo Verde
WP 1
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Site Characterization Results (contd)

• Surface Sources

Groundwater
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Risk Assessment Results

• Potential human health risk associated with
  arsenic and lead in mine waste materials,
  surrounding soils, and the arroyo.
• No immediate human health risk from groundwater
  to offsite drinking water users.

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Removal Action Objectives

• Prevent or reduce human exposure (through
  inhalation, ingestion, and dermal contact) to
  arsenic, lead, and other metals of concern in
  material at the Site
• Prevent or reduce ecological exposure (through
  inhalation, ingestion, and dermal contact) to
  arsenic, lead, and other metals of concern in
  waste material at the Site and
• Prevent or reduce potential migration of arsenic,
  lead, and other metals of concern
• Response Actions
• The proposed removal actions address not only the
  RAOs, but also accommodate the planned future use
  of the property
• The removal criteria for the primary COCs,
  arsenic and lead, have been selected to meet the
  human health site-specific cleanup standards.

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Alternative Development

• Alternative 1 No Action
• Alternative 2 Removal of Contaminated Surface
  Materials and Consolidation in On-Site Repository
• Alternative 3 Excavation of All Material from
  Palo Verde Mine, Auxiliary Waste Piles, and
  Arroyo Partial Removal of Material at Saginaw
  Mine Consolidation in On-Site Repository and
  Capping of Remaining Surface Materials
• Alternative 4 Removal of Contaminated Surface
  Materials to Off-Site Facility (either Hazardous
  Waste Facility or Commercial Landfill)
• Alternative 5 Groundwater Administrative Action
  and Long-Term Monitoring
• Alternative 6 Groundwater Treatment through
  Precipitation and Optional Immobilized Ligand

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Alternative 3 Excavation of All Material
from Palo Verde Mine, Auxiliary Waste Piles, and
Arroyo Partial Removal of Material at Saginaw
Mine Consolidation in On-Site Repository and
Capping of Remaining Surface Materials

• The waste rock and tailings from both the Palo
  Verde Mine and the Saginaw Mine, auxiliary waste
  piles and arroyo would be removed, as would the
  surrounding soils around Palo Verde, into an
  engineered repository at the Saginaw Mine near
  the location of the slag heap.
• This alternative involves five basic actions
• Removal
• Consolidation
• Capping the Repository
• Capping all excavated portions and the
  surrounding soil around Saginaw
• Revegetation on Repository Cap

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Removal

• The following volumes of materials will be
  excavated
• approximately 7,000 cubic yards of waste from
  Palo Verde Mine
• approximately 4,900 cubic yards of waste from
  Saginaw Mine
• approximately 1,450 cubic yards of surrounding
  surface soils in direct contact with waste from
  Saginaw Mine
• approximately 735 cubic yards of surrounding
  surface soils around Palo Verde
• approximately 5,325 cubic yards of arroyo
  sediments
• approximately 150 cubic yards of waste from
  Waste Pile 1 and
• approximately 900 cubic yards of waste from
  Waste Pile 2

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Consolidation in Repository, Repository Capping,
and Repository Revegetation

• Construction of an engineered repository within
  the Saginaw Mine area
• The engineered cover system that has been
  designed to deflect runoff will greatly reduce
  the risk of release of arsenic and lead from the
  contaminated material.
• Repository cap would be vegetated to protect it
  from gullying and scouring by surface water,
  thereby minimizing erosion of the repository.

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Additional Crushed Rock Capping
Repository

• Crushed rock will be placed on all excavated
  areas (except the arroyo) as well as the
  surrounding soil around the Saginaw Mine.
• Rock will be placed in a way to preserve any
  existing vegetation and to a thickness of
  6-inches.
• The repository will be revegetated to prevent
  erosion, and crushed rock may also be used on
  side slopes to aid in the process.

Surface Water Controls
Crushed Rock Cap
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Alternative 5 Groundwater Administrative
Action and Long-Term Monitoring

• Restriction of future use of the site
  (administrative action) Groundwater onsite will
  not be used for drinking water sources
• Nine monitoring wells installed on site

Recommended Monitoring Scheme
Quarterly monitoring first 5 years
Semi-annual monitoring for next 10 years
Annual monitoring for subsequent 15 years, or
longer, as necessary
10 years
5 years
15 years
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Recommended Removal Action

• Alternative 3 for Surface Material Excavation
  of All Material from Palo Verde Mine, Auxiliary
  Waste Piles, and Arroyo Partial Removal of
  Material at Saginaw Mine Consolidation in
  On-Site Repository and Capping of Remaining
  Surface Materials
• Most protective of people
• Does not leave scar on land that must be
  revegetated over a long period of time (crushed
  rock cap instead of scraping all surface soil)
• On-site repository is a safe and cost effective
  way to enclose highly contaminated material, will
  require revegetation but is designed to blend
  with surrounding environment
• Alternative 5 for Groundwater Administrative
  Action and Long-Term Monitoring
• No people are being exposed to groundwater
• Treatment options may not work
• Monitoring will enable BLM to respond to any
  changes
• Treatment can be considered at a later date if
  high levels of metals are observed to be migrating

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Engineering Design
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Auxiliary Piles

• Waste material will be excavated and transported
  to Saginaw mine repository area
• Dust control
• Stabilization of excavated area (soil binder or
  revegetation)
• Existing roads will be used where possible

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Arroyo

• Contaminated sediment will be excavated and moved
  to Saginaw mine repository area
• Existing vegetation will be maintained wherever
  possible
• Saguaro cacti will be transplanted when needed

• Access road along arroyo will be constructed and
  reclaimed
• Arroyo will be armored with riprap to prevent
  erosion

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Palo Verde Excavation

• Excavation of waste material and transport to
  Saginaw mine repository
• Crushed rock cap to be placed on excavated area
  for stabilization

• Existing vegetation maintained where possible
• Use of existing roads where possible
• Dust control
• Confirmation sampling after excavation

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Saginaw Excavation

• Excavation of waste material not currently in
  repository footprint
• Crushed rock cap to be placed on excavated area
  for stabilization

• Existing vegetation maintained where possible
• Use of existing roads where possible
• Dust control
• Confirmation sampling after excavation

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Repository

• Stable slope configuration
• Cap design to minimize / eliminate exposure to
  receptors
• Run-on / Run-off controls
• Revegetation design for repository cap

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Crushed Rock Cap

• Maintain Existing Vegetation wherever possible
• Place crushed rock in excavated areas and on
  surrounding soils elevated above remediation
  levels (6-inches)

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Groundwater Engineering Design

• Currently underway
• Five additional wells installed (9 monitoring
  wells now onsite)
• First round of groundwater sampling completed
• Second round of groundwater sampling being
  conducted in November 2007

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Phased Implementation
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Phase I
WP 2

• Consolidate materials from auxiliary waste piles
  at Saginaw mine repository site
• Excavate contaminated sediments from arroyo and
  consolidate at Saginaw mine repository site
• Stabilize new material placed at Saginaw mine
  repository site with soil binder
• Armor arroyo to prevent erosion
• Stabilize excavated areas with soil binder or
  revegetate

Saginaw
Palo Verde
WP 1
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Phase II
Repository

• Excavate waste material from Palo Verde
• Excavate waste material from Saginaw
• Construct Repository
• Place crushed rock cap on excavated areas and
  surrounding soils
• Construction run-on / run-off controls around
  repository and Palo Verde

Surface Water Controls
Crushed Rock Cap
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Protective Measures During Construction

• Dust monitoring and control
• Air sampling
• Decontamination of all equipment
• Confirmation sampling
• Maintenance of fence

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Groundwater Monitoring Ongoing

• Long term monitoring will continue (not phase
  dependent)

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Community Involvement
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Staying Involved

• www.saginawhill.ene.com
• www.blm.gov/az

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Moving Forward

• James Maes, BLM

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Taking the Next Steps

• Construction for Phase I begins next week
• Duration Approximately 2-3 months
• Phase II Funding Requested

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Thank you

• ecology and environment, inc.
• and
• Bureau of Land Management