Strategies for Long-Term Monitoring
and Stewardship
Craig H. Benson, PhD, PE, NAE
Wisconsin Distinguished Professor
Director of Sustainability Research and Education
University of Wisconsin-Madison/CRESP
Madison, Wisconsin 53706 USA
chbenson@wisc.edu
National Academy of Sciences Workshop
9-10 January 2014
Example: Waste Containment System
Cover system
Gas vent or
collection well
Groundwater
monitoring well
Waste
Native
soil
Groundwater
Barrier
system
Leachate
collection system
Why Monitor? - Monitor for Compliance
Compliance: the common monitoring strategy
• Why: because somebody made us do it.
• Where: where they tell us to monitor
• When: when they tell us to monitor
Shortcomings of Compliance Monitoring
• Impact of deficiency detected long after inception
• Causal deficiency ambiguous
• Limited or no information about mechanisms (no lessons
learned)
Why Monitor? – Monitoring by Function
Monitor by Function: uncommon strategy
• Why: to confirm that feature is functioning as expected
• Where: at location near feature
• When: adequate frequency to characterize behavior
Advantages of Monitoring by Function
• Confidence in methods and procedures
• Evaluate and/or calibrate predictive capability
Disadvantages of Monitoring by Function
• Not meet regulatory requirements
• May not understand mechanisms (requires more info)
ACAP Lysimeter
10 x 20 m lysimeter; 20 x 30 m top deck
Aerial view of completed test sections at Kiefer
Landfill, Sacramento County, California.
Example: Water Balance Cover
• 1.2 m monolithic cover
at Sacramento Cty
Landfill near Rancho
Cordova, CA
Cover designed for
percolation < 1 mm/yr
• Originally vegetated
with perennial
vegetation, including
oleanders, uncommon
in surrounding lands.
Water Balance Data: Sacramento
500
Precipitation
400
1500
300
1000
200
Percolation
500
100
0
7/1/99
7/21/00
8/12/01
9/2/02
9/24/03
0
10/15/04
Percolation (mm)
Cumulative Precipitation (mm)
2000
500
2000
1500
Precipitation
400
Soil
Water
Storage
300
ET
1000
200
Percolation
Surface Runoff
500
100
0
7/1/99
7/21/00
8/12/01
9/2/02
9/24/03
0
10/15/04
Soil Water Storage, Percolation, & Runoff (mm)
Cumulative Precipitation and Evapotranspiration (mm)
Water Balance: With Ancillary Data
Sacramento – Water Content Data
0.4
99-00
00-01
01-02
02-03
03-04
04-05
Volumetric Water Content
Water Year
0.3
0.2
0.1
0-150 mm
150-600 mm
600-900 mm
900-1200 mm
0.0
7/1/99
7/1/00
7/1/01
7/1/02
7/1/03
7/1/04
Decrease in storage capacity ~ 75 mm.
7/1/05
Vegetation Forensics
Soil Water Pressure Potential (- MPa)
Gravimetric Water Content (%)
5% 10% 15% 20% 25% 30% 35% 40%
0.1
1.0
10.0
100.0
0
0
200
Depth Below Ground Surface (mm)
200
400
Thin Test Section
400
Thick Test Section
600
600
Coyote Brush
800
800
Star Thistle and
Prickly Lettuce
1000
1000
1200
Thin Test Section
1200
Other native vegetation can be used to manage
water effectively at this site. Study the natural
analog and infuse it into the design.
1400
Thick Test Section
1400
Coyote Brush
1600
1800
1600
Star Thistle and
Prickly Lettuce
1800
Depth Below Ground Surface (mm)
0%
Some Salient Features of Automated
Monitoring Systems
Monitor remotely if at all possible
• Relying on people to visit site and collect data can be problematic
• Viewing data on demand helps diagnose monitoring problems.
• Depends on frequency at which data must be collected.
Use well-established and reliable hardware
• Savings with low cost vendor lost in data collection &
interpretation
• Consistency in hardware leads to consistency in data
Use flexible and adaptable hardware and deployment
• Long-term monitoring requires revision and updating
• Fernald example
Fernald’s OSDF Double Liner
Fernald’s OSDF Final Cover
14
Monitoring Objective
• Provide data to verify performance of OSDF related
systems
- Are functional requirements being satisfied?
- Design criteria being achieved?
• Provide early warning that will direct problem
mitigation and corrective action
• Provide ability to detect problems that can be corrected
with minor maintenance activities before they become
major problems with costly remedial solutions
• Ensure stakeholder confidence
15
Surface Access
Rod from
settlement plate
Pressure transducer
access (see cabling)
Pressure transducer
16
Sensors: Root Zone Monitoring
Thermal
dissipation
sensor
Water content
reflectometer
Datalogger/Multiplexer Enclosure
Open enclosure showing
datalogger, fiber optic link, etc.
Enclosure mounted on sliders for
easy access from surface location
18
Web-Based Data Presentation
19
20
21
22
23
Decision Flow Chart
u
ud
t
Data record
Drain
Pressure, u
u < ud
Drain Functioning
as Intended
(NO ACTION)
u > ud
Drain NOT Functioning
as Intended
Soil Water
Storage
Distribution
of Pressure
Visual
Observations
See
following
pages
Stewardship
Biggest challenge going forward
• Ensuring surveillance and maintenance with highly constrained
resources – vigilance required
• Create credible and reasonably priced monitoring strategy
• Define credible end point/exit strategy
• Define appropriate budget requirements at onset.
Design systems that require minimal maintenance and
intervention
• Compliant with and mimic sustainable natural systems
• Remotely monitored with monitor-by-function capability
Engage local stakeholders when possible
• Manual data collection
• Inspection
30 cm
Rock Riprap
15 cm
Drainage
45 cm
Protection
Layer
45 cm
UMTRA Disposal Cell
Grand Junction, CO
Precip < 200 mm/yr
Compacted
Soil Layer
(Rn Barrier)
Tailings
Fourwing saltbush
Fourwing Saltbush
26
Monticello Disposal Cell
Water Balance Cover
Water Storage Layer (Sponge)
163 cm
Vegetation (ET)
Gravel Admixture
in Upper 20 cm
61.0 cm
Topsoil
41.0 cm
Growth Medium and
Frost Protection
(Fine-Grained Soil)
30.5 cm
Animal Intrusion Layer
(Cobbles Filled w/ Soil)
30.5 cm
Fine-Grained Soil
38.0 cm
Geotextile Separator
Capillary Barrier
(Coarse Sand)
Cover Monitoring
(3-hectare embedded lysimeter)
Fine Soil
Percolation and Runoff:
Dosing siphons
Capillary
Barrier
Drainage collection
system
28
Soil Moisture Monitoring:
- Water content TDR
- Water potential HDU
Monticello Water Balance
600
NWS
Precipitation
Monticello Water Balance Cover
500
On-Site
Precipitation
4000
Soil Water Storage
NWS
Evapotranspiration
400
3000
300
2000
200
On-Site
Evapotranspiration
1000
Surface Runoff
100
Percolation
0
0
8/1/00
6/19/02
5/7/04
3/25/06
2/11/08 12/29/09 11/17/11 10/5/13
Cumulative Percolation and Surface Runoff,
and Soil Water Storage (mm)
Cumulative Precipitation and Evapotranspiration (mm)
5000
Percolation
< 0.5 mm/y
on average