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