Holistic Approaches to Remediation:

Overcoming Barriers at the Savannah River Site

Jeff Griffin, Ph.D.

Associate Laboratory Director

Environmental Stewardship Directorate

October 30, 2013

Best Practices for Risk-Informed Remedy Selection, Closure, and Post-Closure

Control of Contaminated Sites: A National Academies Workshop

SRNL-MS-2013-00160

Discussion Outline

• Remediation Strategy

oMatch Solution to Problem

o Align Resource Investment to Risk Reduction

oCore Team Process

• Soil and Groundwater Remediation Examples

oContamination with Metals and Radionuclides at SRS F-Area

oContamination with Industrial Solvents at SRS T-Area

• Results

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S&GW Remediation Strategy: Match Solution to Problem

Characteristics • High levels of contamination • Perturbed/complex system • Unstable/evolving conditions • Significant human/

environmental risk

Strategic considerations • Aggressive response • Targeted solutions/technologies • Specialized knowledge and

resources

Characteristics • Moderate levels of contamination • Non-uniform system /environment • Mobile conditions • Long-term risk to humans/ environment

Strategic considerations • Active response • Adaptation of standard solutions • Cost/benefit analysis drives technology

selection • Establish regulatory standards for end

state

Characteristics • Low levels of contamination • Low complexity but large volume or

extended area • Slowly evolving conditions • Small human/ environmental impact

Strategic considerations • Application of finely tuned or passive

solutions • Firm understanding of end-state

criteria • Cost/time balance – impact on

technology selection

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Remediation Examples:

• Low permeability covers minimize the hydraulic spread of

contamination

• Stabilize wastes in place using amendments to alter geochemistry

or reduce permeability

• Thermal technologies evaporate contaminants from solid and liquid

matrices, releasing the gas phase for cost-effective

extraction/capture

• In-situ chemical oxidation chemically destroys organic

contaminants

• Physical removal of waste and contaminated soil/sediment

• Pump and Treat to actively remove or interdict contaminants in

groundwater

Source

D Area Operable Unit

Thermal Detritiation

system treats

contaminated concrete

rubble and soil

excavated from D Area

(“hot rocks”). (Source

material shown is after

treatment.) F Area Seepage Basins During Operations

(top) and After Closure (bottom).

High Impact Zone: Active Remediation

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Intermediate Impact Zone: Enhanced Attenuation

Remediation Examples:

• Hydraulic Control: Modify natural flow

patterns to enable in-situ stabilization of

contaminants

– Barrier walls

o Manage migration of metals,

radionuclides, and tritium

– Phytoremediation pond

o Contain tritiated water as tritium decays

• In-situ Stabilization

– Subsurface amendment injection

o Base injection system neutralizes

acidic groundwater, immobilizing

metals/ radionuclides

o Silver chloride injection captures

radioactive iodine

– Nutrient (“edible oil”) injection decreases

chlorinated compound concentrations by

stimulating anaerobic, abiotic and

cometabolic degradation processes.

February 2011

Hydraulic Barrier to control

groundwater contaminated

with tritium

Funnel and Gate System

with Base Injection

successfully deployed

and operated in F Area

Seepage Basin at SRS,

eliminating active P&T

Funnel Funnel Funnel

Gate

(Base Injection)

“Tan Clay”

Not To Scale

Gate

(Base Injection)

Water Table

Silver Chloride Injection Trailer used

to inject silver chloride amendment for

in-situ treatment of radioactive iodine

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Dilute/Baseline Zone: Passive Monitored Natural Attenuation

Immobilize or detoxify metal or radionuclide contamination in

place in the subsurface

Remediation Examples:

• Passive Soil Vapor Extraction (SVE) in plume fringe & depleted source

zones removes volatile contaminants from soil in the vadose zone

• Monitored Natural Attenuation of organics in plume fringe

Passive SVE: Hundred+ Barometric-Pressure-

Powered Baro Balls in operation across SRS

Solar Powered SVE: Dozens of

Microblowers in operation across SRS;

also Hill AFB

Monitored Natural Attenuation,

Fourmile Branch Seepline

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S&GW Remediation Strategy: Align Resource Investment to Risk Reduction

Low Energy Technologies:

Phytoremediation

Passive Soil Vapor Extraction

(baroballs)

Monitored Natural Attenuation

Highly Aggressive Technologies:

Excavation

Heating (Dynamic Underground Stripping or

Electrical Resistance Heating)

In situ chemical oxidation

Active Soil Vapor Extraction

Less Aggressive Active Technologies:

Air stripping

Recirculation wells

Hydraulic barrier / Phyto-irrigation

Base injection Active Remediation Enhanced Natural Remediation Passive Monitored

Natural Attenuation

High Cost

High Energy Low Cost

Low Energy

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Types

• 78 acre Old Radioactive Waste Burial Ground

• Early Construction Operational Disposal Pits (<1/4 acre)

• Radioactive Seepage Basins & Associated Process Sewer Lines

• Groundwater Operable Units

• Area Operable Units

• Integrator Operable Units

Waste Disposal in the 1950s at the

Burial Ground Complex

Savannah River Site Waste Units

Contaminants

• Metals and Radionuclides

o Sr-90, I-129, U, Pb at SRS

o Cu in SRS outfalls

• Volatile Organics

o Trichloroethylene (TCE) and other solvents at SRS

• Mercury

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Accelerating Closure through Area Completion

• Integrated effort of Area Completion Projects and Savannah River National Laboratory to

address project-specific needs through applied technology

• Provides opportunities for innovative development of holistic strategies

• Results in cost effective, schedule efficient, and improved clean up

14 Consolidated Completion Areas 515 Individual Waste Units

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Core Team Process

A formalized, consensus-based process in which those

individuals with decision-making authority, including DOE,

USEPA, and State, reach agreement on key remediation

decisions

Key Concept: Each organization sends empowered

decision maker and the team makes specific and

actionable agreements.

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DOE US

EPA

State Technical

Staff

Stakeholders

Conventional Approach

DOE US

EPA

State

Technical

Staff

Stakeholders

Cor

e Te

am

Ext

ende

d P

roje

ct T

eam

Core Team Approach • Benefits of a Core Team Approach

o Expedites decision-making

o Improves project focus

o Streamlines documentation

o Minimizes comment/review/revise

process

o Minimizes rework/wasted effort

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Case Study: F-Area

Standard Thinking

Extract contaminated groundwater from natural

environment, treat and dispose of elsewhere

Remediation of Groundwater Contaminated with Metals and Radionuclides at SRS

Innovative Thinking

Work with natural flow patterns rather

than fight against them; sequester and

treat groundwater contaminants in situ

Impact

• Pioneering technology with

potential for worldwide use

• Expends much less energy

• Life-cycle savings of hundreds

of millions of dollars

Standard Practice

Pump and treat of Savannah River Site F-

Area groundwater contaminated with metals

(lead), strontium-90, iodine-129, and uranium

isotopes unsuccessful in achieving return on

investment of energy and expense

Innovative Practice

Develop technologies to employ enhanced natural

attenuation

of contaminants in groundwater using

• Hydrological and flow models

• Engineered structures

• Injection of chemical amendments

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Installation of Funnel and Gate at SRS F Area Seepage Basin

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How the Site Looks Today

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Case Study: T-Area

Context: Anatomy of a Contaminated Plume = f(t)

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Enhanced Attenuation

• An active treatment that results in low risk, plume stability/shrinkage and transition to Monitored Natural Attenuation (MNA)

• Enhanced Attenuation refers to sustainable enhancements designed to be a bridge between active remediation (e.g., pump and treat) and MNA

• SRNL collaborated with a team of the Interstate Technology and Regulatory Council (ITRC) to develop the Flow chart and Technical Regulatory Guidance Document

• Available at www.itrcweb.org

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Six waste pits with over

1 million tons of LLW

BEFORE

8 waste units

29 buildings

TNX (T-Area) Facility, Groundwater, and Vadose Zone Baseline Plan

AFTER

10-acre geosynthetic cover DURING

structures removed

1-2005

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• 15 years of active pump and treat (P&T)/soil vapor extraction (active SVE transitioned to passive SVE)

• Buildings removed, shallow contamination excavated, and site capped

• Continue P&T and PSVE until remedial objectives met (estimated > 30 years at $1M/yr)

Concentrations: 1992: up to 5000 ug/L 2008: up to 600 ug/L

Application of Enhanced Attenuation: Structured Geochemical Zones

• Encourage plume to flow through a series of anaerobic and aerobic treatment zones o Deploy emulsified edible oil in plume core to form multiple treatment & bioreactor zones

o Deploy neat edible oil in vadose zone to form “water table” barrier and limit impact of residual soil sources

• Increase overall attenuation rates in plume

• Take advantage of complementary strengths of anaerobic and aerobic degradation processes

• Take advantage of physical partitioning for near term concentration and mass discharge reduction

• Scientific underpinning for Core Team/regulatory acceptance

• SRS T-Area remediation strategy presently being applied to remediation of other sites, such as the Mound site in Ohio

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T-Area Groundwater Remediation: Enhanced Attenuation

monitor until

remedial objectives

are met

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Emplacement of edible (pure soybean) oil for attenuation

of vadose zone contaminated with chlorinated solvents

Injection of supplemental emulsified oil for attenuation of low-

level contamination below water table

Expect to meet

standards in

plume in 10

years

SRS Soil and Groundwater Remediation Program

SRS has a mature and diverse soil and groundwater remediation program.

SRNL delivers innovation to expedite risk reduction.

• SRS

– Hazardous and radiological contaminants

– All media and a wide variety of settings

– >399 of 515 waste sites closed

– >30 groundwater remediation operating systems

– Extensive and robust environmental multimedia data management system

• Technical Assistance Program

― Builds on success at SRS in developing and applying innovative and efficient technical

solutions to challenging environmental problems

― Have performed independent reviews and recommended diverse remedies at numerous

sites both nationally and internationally

o Since 2006, 25 teams have visited 11 DOE sites and made recommendations yielding

~$100M cost savings

o Ukraine, Japan

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