Research on engineered barrier technology by cresp s landfill partnership
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Research on Engineered Barrier Technology by CRESP's Landfill Partnership. Craig H. Benson, PhD, PE, DGE Wisconsin Distinguished Professor University of Wisconsin-Madison/CRESP [email protected] On-Site Disposal Facility (OSDF): aka LLW or MW Landfill. Final Cover System. MONITORING

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Research on Engineered Barrier Technology by CRESP's Landfill Partnership

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Research on engineered barrier technology by cresp s landfill partnership

Research on Engineered Barrier Technology by CRESP's Landfill Partnership

Craig H. Benson, PhD, PE, DGE

Wisconsin Distinguished Professor

University of Wisconsin-Madison/CRESP

[email protected]


On site disposal facility osdf aka llw or mw landfill

On-Site Disposal Facility (OSDF):aka LLW or MW Landfill

Final

Cover

System

MONITORING

WELLS

Liner

System

Figure courtesy M. Othman, Geosyntec Consultants


The challenge confident design for a millennium

The Challenge – Confident Design for a Millennium

?

?

Current Field

Research &

Experience

?

Engineering Property

As-Built

Analogs

100

1000

1

10

Time (years)


Purpose of landfill partnership

  • Conduct independent applied research to address landfill technology issues that cross-cut the DOE complex.

  • Provide forum to discuss regulatory conflicts and shortcomings, and to recommend technological solutions.

  • Participate in independent technical reviews related to DOE technologies or sites.

Purpose of Landfill Partnership


Relevance

  • OSDFs (landfills) are key step in D&D/restoration at EM sites; stakeholder concerns regarding long-term performance impede acceptance/permitting.

  • NAS (2009) identifies existing knowledge on long-term performance of waste containment structures as a principle science and technology gap for EM. Credibility gap for stakeholders.

  • LP to provide source terms for EM’s ASCEM (analogous to CBP).

Relevance


Technical priorities to build confidence

Technical Priorities to Build Confidence

  • Develop confidence in the long-term (1000 yr) performance of OSDF designs.

  • Understanding of degradation mechanisms affecting containment systems in OSDFs.

  • Understand and quantify how final covers evolve over the design life of OSDFs.

  • Develop confidence in models used for PAs of OSDFs and characterize uncertainty in predictions.

  • Create and evaluate monitoring strategies that build confidence in the performance of OSDFs.


Approach to build technical confidence

Approach to Build Technical Confidence

  • Understand our existing technology – does it work as well as we predict?

  • Understand how barriers degrade or evolve over time so that we can make confident long-term predictions.

  • Develop reliable methods (e.g., computer tools) to predict performance in as-built state, and as barrier degrades.


1 understanding our existing technology

1. Understanding our Existing Technology

  • State-of-the-art: knowledge base from field studies of barrier performance.

    • Resistive barrier technologies

    • Water balance barrier technologies

  • State-of-the-art: lessons learned from field studies of cover soil pedogenesis.

  • Leachate source terms for LLW disposal facilities.


2 developing prediction methods

2. Developing Prediction Methods

  • Mechanistic description of radionuclide sorption and diffusion in barrier systems.

  • Assessing methods to measure radionuclide sorption and diffusion in barrier systems

  • Accounting for large-particle effects in soil water retention.

  • Efficacy of transport models for predicting transport through barrier systems.

  • Evaluating how input uncertainty/sparseness affects uncertainty in model predictions.


3 understanding barrier degradation

3. Understanding Barrier Degradation

  • Geomembrane degradation & life expectancy in LLW facilities.

  • Degradation of bentonite barriers due to ion exchange, hydration-exchange kinetics, and environmental stress (freezing, drying).

  • Degradation of bentonite barriers exposed to concrete surfaces.

  • Design strategies that manage degradation & ensure adequate performance (e.g., evolutionary covers, surface treatments).


Geomembrane degradation

Geomembrane Degradation

Speculative discussion at Paducah in March ‘11.

Literature suggests lifespan may be more than 1000 yr.

No data for conditions in LLW or MW facilities.

No credible scientific data for LLW or MW to draw inference, but methods from solid waste literature


Durability tests in synthetic llw leachate

Durability Tests in Synthetic LLW Leachate

  • Three temperatures (50, 70, & 90 C)

  • Three solutions (DI, LLW, and LLW-Rad)

  • 2 mm HDPE (ERDF, OSDF).


Geomembrane incubators

Geomembrane Incubators


Major cations in llw leachate

Major Cations in LLW Leachate


Radionuclides u and tc

Radionuclides: U and Tc


Temporal behavior u and tc

Temporal Behavior: U and Tc


Temporal behavior sr and tritium

Temporal Behavior: Sr and Tritium


Coupling hydrological erosion control on covers

Coupling Hydrological & Erosion Control on Covers

  • Used Cheney Disposal Facility (Grand Junction, CO) as base case

  • SIBERIA landform evolution model (1000 yr simulation)

  • SVFLUX variably saturated flow model for hydrology.


Erosion on rip rap covers

Erosion on Rip-Rap Covers

Rip-rap surface layer


Coupling hydrological erosion control on covers gravel admixture cover

Coupling Hydrological & Erosion Control on Covers: Gravel Admixture Cover

Gravel Admixture Topsoil Surface Layer


Hydrological prediction for grand junction co

Hydrological Prediction for Grand Junction, CO

  • Gravel admixture covers have net release to atmosphere

  • Rip-rap covers harvest water – collect and drain into waste.

  • Similar efficacy for erosion control!

Flow

Out of Waste

Flow

Into Waste


Transport parameters for barriers

Transport Parameters for Barriers

Diffusion and sorption tests for geomembranes.

Evaluating new geomembrane with exceptionally low radon diffusion coefficient.


Transport prediction for barriers

Transport Prediction for Barriers


Prediction tce transport in clay barrier

Prediction - TCE Transport in Clay Barrier

Forward “Class A” predictions using independently measured input parameters (not calibrated)


Summary remarks

Summary Remarks

  • Independent basic to applied research focused on developing confidence in containment facilities.

  • Focus on topics that our stakeholders indicate are important.

  • Assess full-scale facilities and near full-scale demonstrations, understand fundamental mechanisms, and create/validate predictive models.


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