The CRESP Landfill Partnership focuses on understanding and predicting the long-term performance of landfill containment systems through laboratory, field, and modeling work. It develops sustainable and economical containment technologies and solutions to address challenging waste issues like mercury and technetium-99. The partnership also provides site-specific problem solving for containment issues at on-site disposal facilities.

1. CRESP’s Landfill Partnership:
Applied Research to Solve Challenging
Problems for On-Site Disposal Facilities
Craig H. Benson, PhD, PE, NAE
University of Virginia/CRESP
chbenson@virginia.edu
Waste Management 2019

2. Engineered Barriers and Containment Systems
Waste
Radon Flux
Water
Percolation
Flux to groundwater
Landfill Partnership focuses on:
- Understand and predict long-term performance (lab, field, modeling).
- Develop and demonstrate sustainable, effective, and economic strategies.
- Develop innovative solutions to address difficult problems (Hg, Tc-99).
- Provide site-specific problem solving on containment issues.

3. Challenges – Predicting the Future
1 10 100 1000
EngineeringProperty
Time (years)
As-Built
ACAP
Exhumations
?
?
?
Analogs
Radon Flux
Project
Authoritative information to shape, parameterize, & justify PAs for on-site disposal facilities.

4. Perspectives Change Based on Data

5. 5
Service Life of Engineered Barriers

6. Sustainable & Economical Containment Technologies
U Tailings
Rip Rap
Clay Radon
Barrier
Frost
Protection
Layer
Bedding
305 mm
610 mm
610 mm
150 mm
Armored Cover with
Clay Rn Barrier
Vegetation on the surface is controlled with herbicide – no vegetation on cover
Two identical test sections, C & R

7. Transforming Covers for Improved Long-Term
Performance with Less Maintenance
0
500
1000
1500
0
5
10
15
20
25
30
10/31/07 12/10/08 1/21/10 3/3/11 4/13/12 5/24/13 7/5/14
Cheney (R)
CumulativePrecipitation,ET,and
SoilWaterStorage(mm)
CumulativeRunoffandPercolation(mm)
Soil Water Storage
Surface Runoff
Percolation
Precipitation
Evapotranspiration
Percolation into waste is increasing over time
due to structural development in barrier.
Strategies Being Explored:
- Stop spraying & allow
vegetation to establish,
providing root water
uptake from cover.
- Blending/mixing of surficial
layers to deliberately
transform cover into a
vegetated water
balance/ET cover
- Radionuclide uptake?
U Tailings
Rip Rap
Clay Radon
Barrier
Frost
Protection
Layer
Bedding
305 mm
610 mm
610 mm
150 mm
Improves performance, reduces long-term cost and maintenance.

8. • Multi-sorbing bentonite barriers have very low
hydraulic conductivity (hydraulic barrier) and are highly
effective in binding metals, non-polar organic
compounds, and oxyanions (contaminant
sequestration).
• Blend of conventional bentonite, organoclay, and
zeolite.
0
50000
100000
150000
200000
0 10 20 30 40 50 60 70
DI water
LLW
SolidphaseTc-99concentrationon
mutlisorbingclay(pCi/g)
Equilibrium Tc-99 concentration (pCi/mL)
Kd
= 5066 mL/g
Kd
= 2945 mL/g
Tian, K. and Benson, C. (2018), Containing Tc-99
Using a Multi-Sorbing Barrier Material, Proc.
Waste Management ’18.
Innovation to Solve Complex Disposal Problems:
Multi-Sorbing Low Conductivity Bentonite Barrier

9. Site-Specific Problem Solving:
Elevated Pressures at Oak Ridge’s EMWMF
PP-01
Uh-ho! We were not expecting
positive pore water pressures!!
Session 122, 8 AM Thursday, Room 106C

10. 10
CRESP’s Landfill Partnership focuses on:
-Understand and predict long-term performance (lab, field,
modeling). Data are good!
-Develop and demonstrate sustainable, effective, and economic
strategies.
-Develop innovative solutions to address difficult problems (Hg,
Tc-99).
-Site-specific problem solving for on-site disposal facility issues.