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Fluid dynamic processes within a closed repository with or without long-term monitoring
7th US/German Workshop on Salt Repository Research, Design, and Operation
R. Wolters, K.-H. Lux, U. Düsterloh
Chair in Waste Disposal and GeomechanicsClausthal University of Technology
September 7-9, 2016Washington, DC
2Fluid dynamic processes within a closed repository
with or without long-term monitoring
Outline
• Long-Term Monitoring Options
• Fluid Dynamic Processes within a Closed Repository
• TH2M-Coupled Simulation Tool FTK
• Numerical Simulation Results
• Conclusions
3Fluid dynamic processes within a closed repository
with or without long-term monitoring
Outline
• Long-Term Monitoring Options
• Fluid Dynamic Processes within a Closed Repository
• TH2M-Coupled Simulation Tool FTK
• Numerical Simulation Results
• Conclusions
4Fluid dynamic processes within a closed repository
with or without long-term monitoring
Long-Term Monitoring Options
Motivation
In Germany, according to its recommendations, the Repository Commission prefers the disposal of high-level waste within a repository built in deep geological formations.
But:
Reversibility of decisions as well as retrievability of the waste canisters should be possible for future generations because there might be a significant improvement of scientific knowledge and technology concerning the handling of high-level waste or there might occur an unexpected development of the repository system.
For this reason, a long-term monitoring option should be implemented into the repository concept to provide data about the time-dependent physical as well as chemical situation within the repository system.
How could a long-term monitoring option be realized?
5Fluid dynamic processes within a closed repository
with or without long-term monitoring
Long-Term Monitoring Options
Swiss Monitoring ConceptSource: Nagra-Webpage
How can the measured data be transferred from the pilot facility to the main facility?How to be sure that the main facility works correctly if the pilot facility works correctly?
1 Main facility SF/HLW2 ILW repository3 Pilot facility4 Test zones5 Access tunnel6 Ventilation shaft and construction shaft
6Fluid dynamic processes within a closed repository
with or without long-term monitoring
Long-Term Monitoring Options
2-Level Repository Concept
Emplacement Level Monitoring Level Monitoring Boreholes
Monitoring of every single emplacement drift is possible!
7Fluid dynamic processes within a closed repository
with or without long-term monitoring
Long-Term Monitoring Options
2-Level Repository Concept
Emplacement Level- backfilled and sealed like in repository concept without monitoring option
Monitoring Level- access to monitoring boreholes- kept open during monitoring phase- backfilled and sealed after monitoring phase (including shaft closure)
Monitoring Boreholes- drilled to emplacement drifts and instrumented before waste emplacement- provide access to measurement equipment for repair, energy supply, and data
transfer- kept internally open during monitoring phase, but covered by some kind of moveable
sealing construction at the upper end of the boreholes- lined to prevent borehole convergence during monitoring phase- (unlined?,) backfilled, and sealed after monitoring phase
8Fluid dynamic processes within a closed repository
with or without long-term monitoring
Outline
• Long-Term Monitoring Options
• Fluid Dynamic Processes within a Closed Repository
• TH2M-Coupled Simulation Tool FTK
• Numerical Simulation Results
• Conclusions
9Fluid dynamic processes within a closed repository
with or without long-term monitoring
Fluid Dynamic Processes within a Closed Repository
Mechanical Processes Salt rock mass:
- Creep behaviour- Thermomechanically induced damage leading to an increase of secondary porosity as well
as of secondary permeability- Sealing/healing of microfissures- Stress redistribution
Crushed salt:- Compaction leading to a reduction of porosity and permeability as well as to increasing
compaction stresses
Hydraulic Processes Flow of liquids and gases (2-phase flow) Increase of gas pressure due to temperature increase, gas compression, and gas
generation Hydraulically induced damage in salt rock mass / pressure-driven fluid infiltration
Thermal Processes Heat conduction considering non-constant thermal properties
10Fluid dynamic processes within a closed repository
with or without long-term monitoring
Outline
• Long-Term Monitoring Options
• Fluid Dynamic Processes within a Closed Repository
• TH2M-Coupled Simulation Tool FTK
• Numerical Simulation Results
• Conclusions
11Fluid dynamic processes within a closed repository
with or without long-term monitoring
, ,, ,
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P : pore pressureT : temperatureSl : liquid saturation
k : permeabilityf : porosity
s : stresse : straint : time
Legend:
TH2M-Coupled Simulation Tool FTK
The TH2M-coupled simulation tool FTK is based on the two numerical codes FLAC3D and TOUGH2.
Mechanical and thermohydraulic processes are sequentally simulated.
12Fluid dynamic processes within a closed repository
with or without long-term monitoring
Constitutive Model Lux/Wolters
Dilatancy Boundary ss ,3 332 JF ds
Additional Creep Rate in Sealed/Healed Zones
modLubby2: D 1ss
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DamageRate
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Additional CreepRate in Damaged Zones
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Sealing/Healing Boundary
Sealing/Healing Rate
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no further damage orsealing/healing
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TH2M-Coupled Simulation Tool FTK
13Fluid dynamic processes within a closed repository
with or without long-term monitoring
Outline
• Long-Term Monitoring Options
• Fluid Dynamic Processes within a Closed Repository
• TH2M-Coupled Simulation Tool FTK
• Numerical Simulation Results• Process Modelling• System Modelling
• Conclusions
14Fluid dynamic processes within a closed repository
with or without long-term monitoring
Numerical Simulation Results – Process Modelling
3D-Simulation of TSDE-Experiment FLAC3D-Berechnungsmodell Voronoi-Diskretisierung für TOUGH2
FLAC3D-Berechnungsmodell Voronoi-Diskretisierung für TOUGH2
Blanco-Martín, L., Wolters, R., et al. (2016)
FLAC3D-Model
Voronoi-Discretization for TOUGH2
15Fluid dynamic processes within a closed repository
with or without long-term monitoring
3D-Simulation of TSDE-ExperimentBlanco-Martín, L., Wolters, R., et al. (2016)
Numerical Simulation Results – Process Modelling
16Fluid dynamic processes within a closed repository
with or without long-term monitoring
3D-Simulation regarding the Monitoring Borehole Concept
Numerical Simulation Results – Process Modelling
z = -560 m
z = -800 m
z = -400 m
z = -600 m
L = 50 mB = 11 m
Monitoringstrecke
Bohrlöcher
Einlagerungsstrecke
Stahlmann et al. (2016)
Shape of Emplacement Drift Shape of Monitoring Drift
Emplacement Drifts
Monitoring Boreholes
Monitoring Drift
17Fluid dynamic processes within a closed repository
with or without long-term monitoring
3D-Simulation regarding the Monitoring Borehole Concept
Numerical Simulation Results – Process Modelling
1 Waste Canister (5,5m) 1/2 Waste Canister
Backfill Material
(5,5m)
Monitoring Borehole
Monitoring Borehole (0,1m2)
Crushed Salt
Main Components of the 3D-Model Monitoring Drift
Emplacement Drift
A
B
1/2 Waster Canister
Crushed Salt
B
A
Emplacement DriftMonitoring Borehole
Crushed Salt
18Fluid dynamic processes within a closed repository
with or without long-term monitoring
Outline
• Long-Term Monitoring Options
• Fluid Dynamic Processes within a Closed Repository
• TH2M-Coupled Simulation Tool FTK
• Numerical Simulation Results• Process Modelling• System Modelling
• Conclusions
19Fluid dynamic processes within a closed repository
with or without long-term monitoring
3D-Simulation of a Repository System in Rock Salt Masswithout Monitoring Level
Numerical Simulation Results – System Modelling
20Fluid dynamic processes within a closed repository
with or without long-term monitoring
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
2. Panel 3. Panel1. Panel
→ Schachtt = 0,274 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 0,671 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 1,05 at = 0,85 a
2. Panel 3. Panel1. Panel
→ Schacht
21Fluid dynamic processes within a closed repository
with or without long-term monitoring
2. Panel 3. Panel1. Panel
→ Schacht
t = 1,23 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 1,57 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 1,76 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 1,94 a
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
22Fluid dynamic processes within a closed repository
with or without long-term monitoring
2. Panel 3. Panel1. Panel
→ Schacht
t = 2,13 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 2,47 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 2,81 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 3,15 a
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
23Fluid dynamic processes within a closed repository
with or without long-term monitoring
2. Panel 3. Panel1. Panel
→ Schacht
t = 3,28 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 3,41 a
2. Panel 3. Panel1. Panel→ Schacht
t = 3,54 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
24Fluid dynamic processes within a closed repository
with or without long-term monitoring
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
25Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 6,24 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 6,37 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 5,53 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 5,67 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
26Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 7,66 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 7,79 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 6,95 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 7,08 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
27Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 9,07 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 9,21 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 8,37 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 8,50 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
28Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 10,49 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 10,62 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 9,78 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 9,91 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
29Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 11,90 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 12,04 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 11,20 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 11,33 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
30Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 13,32 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 13,45 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 12,61 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 12,74 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
31Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 14,74 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 15,31 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 14,03 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 14,16 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
32Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 17,04 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 19,04 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 15,89 a
2. Panel 3. Panel1. Panel
→ Schacht
t = 16,46 a
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
33Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 30 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 40 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 10 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 20 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
34Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 70 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 80 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 50 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 60 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
35Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 200 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 300 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 90 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 100 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
36Fluid dynamic processes within a closed repository
with or without long-term monitoring
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
t = 600 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 700 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 400 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 500 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
37Fluid dynamic processes within a closed repository
with or without long-term monitoring
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
t = 600 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 700 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 400 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 500 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 1.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 2.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 800 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 900 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
38Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 5.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 6.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 3.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 4.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
39Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 9.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 10.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 7.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 8.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
40Fluid dynamic processes within a closed repository
with or without long-term monitoring
t = 9.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 10.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 7.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
t = 8.000 a nach Verschluss
2. Panel 3. Panel1. Panel
→ Schacht
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
41Fluid dynamic processes within a closed repository
with or without long-term monitoring
0
20
40
60
80
100
120
140
160
1 10 100 1000 10000 100000 1000000
Tem
pera
tur [�C
]
Zeit nach Verschluss [a]
Time-dependent Temperature Evolution
Numerical Simulation Results – System Modelling
1
4
5
2 3
42Fluid dynamic processes within a closed repository
with or without long-term monitoring
Time-dependent Porosity Evolution
Numerical Simulation Results – System Modelling
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
1 10 100 1000 10000 100000 1000000
Poro
sitä
t [-]
Zeit nach Verschluss [a]
1
4
5
2 3
43Fluid dynamic processes within a closed repository
with or without long-term monitoring
0
2
4
6
8
10
12
14
16
18
20
1 10 100 1000 10000 100000 1000000
Pore
ngas
druc
k [M
Pa]
Zeit nach Verschluss [a]
Time-dependent Gas Pressure Evolution
Numerical Simulation Results – System Modelling
1
4
5
2 3
44Fluid dynamic processes within a closed repository
with or without long-term monitoring
Gas Flow within Repository System (t = 10 a after repository closure)
Numerical Simulation Results – System Modelling
↑ Schacht
↓ 1. & 2. Einlagerungsfeld← weitere Einlagerungskammern im 3. Einlagerungsfeld
ca. 0,0043 N-m³/a/m²
ca. 0
,057
N-m
³/a/m
²
ca. 0
,0 N
-m³/a
/m²
45Fluid dynamic processes within a closed repository
with or without long-term monitoring
ca. 0,1356 N-m³/a/m²
ca. 0
,072
2 N
-m³/a
/m²
ca. 0
,035
N-m
³/a/m
²↑ Schacht
↓ 1. & 2. Einlagerungsfeld← weitere Einlagerungskammern im 3. Einlagerungsfeld
Gas Flow within Repository System (t = 1.000 a after repository closure)
Numerical Simulation Results – System Modelling
46Fluid dynamic processes within a closed repository
with or without long-term monitoring
ca. 0,046 N-m³/a/m²
ca. 0
,041
N-m
³/a/m
²
ca. 0
,023
N-m
³/a/m
²↑ Schacht
↓ 1. & 2. Einlagerungsfeld← weitere Einlagerungskammern im 3. Einlagerungsfeld
Gas Flow within Repository System (t = 10.000 a after repository closure)
Numerical Simulation Results – System Modelling
47Fluid dynamic processes within a closed repository
with or without long-term monitoring
ca. 0,00159 N-m³/a/m²
ca. 0
,0 N
-m³/a
/m²
ca. 0
,001
13 N
-m³/a
/m²↑ Schacht
↓ 1. & 2. Einlagerungsfeld← weitere Einlagerungskammern im 3. Einlagerungsfeld
Gas Flow within Repository System (t = 200.000 a after repository closure)
Numerical Simulation Results – System Modelling
48Fluid dynamic processes within a closed repository
with or without long-term monitoring
Gas Infiltration into Salt Rock Mass (t = 8.000 a after repository closure)
Numerical Simulation Results – System Modelling
t = 8.000 Jahrenach Verschluss des Endlagers
t = 80.000 Jahrenach Verschluss des Endlagers
0
2
4
6
8
10
12
14
16
18
20
1 10 100 1000 10000 100000 1000000
Pore
ngas
druc
k [M
Pa]
Zeit nach Verschluss [a]
49Fluid dynamic processes within a closed repository
with or without long-term monitoring
Gas Infiltration into Salt Rock Mass (t = 20.000 a after repository closure)
Numerical Simulation Results – System Modelling
0
2
4
6
8
10
12
14
16
18
20
1 10 100 1000 10000 100000 1000000
Pore
ngas
druc
k [M
Pa]
Zeit nach Verschluss [a]
50Fluid dynamic processes within a closed repository
with or without long-term monitoringt = 8.000 Jahrenach Verschluss des Endlagers
t = 80.000 Jahrenach Verschluss des Endlagers
Gas Infiltration into Salt Rock Mass (t = 80.000 a after repository closure)
Numerical Simulation Results – System Modelling
0
2
4
6
8
10
12
14
16
18
20
1 10 100 1000 10000 100000 1000000
Pore
ngas
druc
k [M
Pa]
Zeit nach Verschluss [a]
51Fluid dynamic processes within a closed repository
with or without long-term monitoring
3D-Simulation of a Repository System with Monitoring Level
Numerical Simulation Results – System Modelling
52Fluid dynamic processes within a closed repository
with or without long-term monitoring
Gas Flow within Repository System (t = 900 a after repository closure)
Numerical Simulation Results – System Modelling
ca. 0,0014 N-m³/a/m²
ca. 0
,24
N-m
³/a/m
²
ca. 0
,238
N-m
³/a/m
²
ca. 0,000885 N-m³/a/m²
ca. 0,0144 N-m³/a/m²
Einlagerungssohle
Überwachungssohle
Bohrlöcher
53Fluid dynamic processes within a closed repository
with or without long-term monitoring
Outline
• Long-Term Monitoring Options
• Fluid Dynamic Processes within a Closed Repository
• TH2M-Coupled Simulation Tool FTK
• Numerical Simulation Results
• Conclusions
54Fluid dynamic processes within a closed repository
with or without long-term monitoring
Conclusions
Capabilities of the simulation tool FTK to evaluate the barriers integrity over time including TH2M-coupled processes like rock mass convergence, backfill compaction, heat production, gas production, 2-phase flow, and pressure-driven infiltration have already been demonstrated in former works, e.g. at SaltMech 8 or at 5th US/German Workshop on Salt Repository Research, Design, and Operation.
The simulation tool FTK can be used to analyze the long-term TH2M-coupled behaviour of a repository system in salt rock mass without or with monitoring option.
Numerical simulation of fluid dynamics in a closed repository in rock salt without monitoring option shows:
- Maximum temperature stays below .- Temperature field reaches primary temperature after about 10,000 years.- Primary pore air within crushed salt as well as corrosion gases are squeezed out through drifts and
shafts as well as through the geologic barrier due to the pressure-driven gas infiltration process.
Numerical simulation of fluid dynamics in a closed repository in rock salt with monitoring option via monitoring boreholes shows:
- Temperature at monitoring level amounts about in maximum.- Gas escapes from the emplacement level to the monitoring level through the monitoring boreholes
resulting in a less intensive gas pressure build-up within the repository system.
55Fluid dynamic processes within a closed repository
with or without long-term monitoring
Conclusions
Some benefits of the implementation of a monitoring level in combination with monitoring boreholes:
Monitoring boreholes enable direct measurement of physical parameters during post-closure transition phase.
Monitoring boreholes give a possibility to indicate measurement errors and to replace measurement equipment in case of cancellation.
Direct monitoring may increase confidence as well as public acceptance.
But:
Direct monitoring via monitoring level in combination with monitoring boreholes may influence the site selection criteria (e.g. thickness as well as lateral extension of geological barrier formation) and has therefore to be implemented in the site selection process.