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Presentation by Tyler Chatriand, PE, Sovereign Consulting Inc. Seattle, Washington branch. "Replacing an Aged Lime Treatment Plant with Passive and Semi-Passive Treatment Techniques." Presented during Energy and Waste Management Session to the American Waste Management Association - Pacific Northwest International Section at the 53rd Annual Conference on November 8, 2013.
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Replacing an Aged Lime Treatment Plant with Passive and Semi-Passive
Treatment Techniques
Presented by:
Tyler Chatriand, PE
Sovereign Consulting Inc.
Mine Water Treatment Options
Active Treatment Uses chemicals, energy, labor, & infrastructure to produce clean water in the
shortest time & smallest possible footprint
Passive Treatment Capitalizes on the low-energy dynamics employed in natural biological and
geochemical processes at ambient temperatures
No moving parts or power requirements => Simple to operate Resilient to quantity variations (flow rates, temp, chemistry) Blends into landscape, wildlife habitat Low O&M Large footprint, long HRT, high capital
Semi-Passive Treatment Utilizes moving parts and chemicals WITHOUT continuous power and labor
required for active treatment systems
ARD is formed by the oxidation of sulfide minerals when exposed to air and water.
Acidithiobacillus ferrooxidans – metabolizes iron and sulfur to produce sulfuric acid
The Problem - Acid Rock Drainage (ARD)
Stumm and Morgan, 1981 Gusek, 2004
Project Background
Inactive Coal Mine in Western PA
Surface Mine
2 Underground Mines
Upper Freeport coal seam
Kiskiminetas coal seam
3 Coal Refuse Disposal Areas
Waste rock piles – Acid Rock Drainage (ARD)
Vicinity Map
Active Mining - 1993
Post Mining - 2006
Treatment Plant
Coal Refuse Area #5
Coal Refuse Area #4
Coal Refuse Area #6
Hydrated Lime Feed Plant
• 25+ yrs old
• Weak structural integrity
• Inadequate pump system
• Single stage treatment
• Insufficient Mn/Al removal
• Clean stormwater routed below compliance point
Existing ARD Treatment
Treatment Alternatives Analyses
Passive vs. Active? Hybrid
Site Characterization
Review Historical Data
Inventory ARD Sources
Establish Monitoring and Gaging Stations
Evaluate Water Chemistry and Contaminant Loadings
Identify Treatment Alternatives
ARD Sources
Conceptual Site Model
Proposed Semi-Passive System
Alternatives Analysis
Economic Analyses
New Active Plant vs. Semi-Passive
Treatment
Option
Capitol
Cost
Annual
O&M
Total Cost
Year 1
Total Cost
Year 5
Total Cost
Year 10
Total Cost
Year 20
Total Cost
Year 30
Hybrid Passive
Train $2,419,568 $120,360 $2,539,928 $3,021,367 $3,623,167 $4,826,766 $6,030,364
Lime Treatment
Plant $1,922,845 $400,000 $2,322,845 $3,922,845 $5,922,845 $9,922,845 $13,922,845
Pebble Quicklime at ARD Source
Aquafix – water wheel driven chemical feed system
Pond 14 Lime Dosing Footprint
400 sf
Passive Mixing/Aeration – BioMost, Inc
MixWell A-Mixer
BioMost, Inc BioMost, Inc
Passive Aeration - Trompe
Water-powered air compressor
For every 4’ TDH,
= 1 cfm/25 gpm
Pond 14 Outfall = 13’
3 Trompes in series
= 4 CFM at base flow
Field Pilot Testing
Source Control
Back to the ARD Tetrahedron
Remove the Source
Circulating Fluidized Bed Combustion
Impermeable cap – high cost
In-situ treatment
pHoamTM injection technology Waste milk, Biosolids, Surfactants (SLS)
Biochemical reactor (BCR) effluent
Source Control – BCR Effluent
BCR - uses sulfate-reducing bacteria to produce sulfide and bicarbonate, allowing metals to precipitate as metal sulfides.
Excess alkalinity generated by sulfate reducing bacteria and limestone dissolution in the BCR substrate
Excess dissolved sulfide ion, which can bind with dissolved ferrous iron to form iron mono-sulfide coatings/deposits, and
Dissolved manganese which could coat pyritic refuse in deeper, more aerobic zones of the refuse area with manganese oxide.
Recap
Semi-Passive Treatment is a viable, cost-effective alternative to solely active or passive treatment Treat at the source - reduce SW impacts, flow flux, reclaim stream
Small footprint
Increased chemical utilization
No power required - reliable
Minimal labor – periodic inspections
Low capital and O&M
Effective – meet stringent discharge permit limits
Innovative Source Control Methods Water treatment in perpetuity
Eliminate the source Only walk-away solution
Stage 3 Reclamation Bond Release
Questions?
Tyler Chatriand, PE, CFM
Environmental Engineer | email: [email protected]
Office: 206.812.8265
Cell: 406.471.0436
Sovereign Consulting Inc.
2101 Fourth Ave, Suite 2130
Seattle, WA 98121
www.sovcon.com
