Published on February 18, 2014
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
The Problem - Acid Rock Drainage (ARD) 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 Gusek, 2004 Stumm and Morgan, 1981
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)
Active Mining - 1993
Post Mining - 2006 Coal Refuse Area #5 Coal Refuse Area #4 Coal Refuse Area #6 Treatment Plant
Existing ARD Treatment 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 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
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 BioMost, Inc A-Mixer 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: firstname.lastname@example.org Office: 206.812.8265 Cell: 406.471.0436 Sovereign Consulting Inc. 2101 Fourth Ave, Suite 2130 Seattle, WA 98121 www.sovcon.com
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News article: Replacing an Aged Lime Treatment Plant with Passive and Semi-Passive Treatment Techniques
Presentation by Tyler Chatriand, PE, Sovereign Consulting Inc. Seattle, Washington branch. "Replacing an Aged Lime Treatment Plant with Passive and Semi-Passiv
Replacing an Aged Lime Treatment Plant with Passive and Semi-Passive Treatment Techniques... Presentation by Tyler Chatriand, PE, Sovereign Consulting I...
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