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Published byCornelia Thys Modified over 5 years ago
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Coal Waste Storage Area Pond Design/Build Project Stanton Energy Center
Chip Merriam Chief Legislative & Regulatory Compliance Officer
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Background Built in 1987 as part of original SEC construction
Needs replacement Plan to make significant improvements
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SEC WASTE POND LOCATIONS
Text SEC WASTE POND LOCATIONS
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Design Issues Drain Design Liner Design Fabriform Design
Filter sock around drain pipe without gravel pack generally ineffective Drain positioned too far inward Liner Design Tensile Stresses – low frictional resistance between smooth HDPE liner and geotextile on 3:0H to 1:0V slope Gas vent elevation too low, allowed submergence Fabriform Design Tensile Stresses – low frictional resistance between fabriform and smooth HDPE liner
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Technical Approach
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Engineering Design Dike Elevation Pond Footprint Liner System
Liner Thickness Drain Sequence of Construction Water Quality
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EXPANDED POND ( 9.5 Acres) COAL COMBUSTION WASTE AREA RUNOFF POND (4.5 Acres) EXISTING LANDFILL HORIZONTAL EXPANSION CELL 1 (35 Acres) VERTICAL EXPANSION CELL 1 (12 Acres)
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Coal Combustion Waste Area Runoff Pond
NORTH SOUTH ELEVATION 89’ NATURAL GROUND ELEVATION 85’ to 86’ FABRIFORM 18-INCH THICK SOIL COVER HDPE LINER UNDERDRAIN
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Design Selection Serviceability Capital and Operational Cost
Constructability Impact to Operation Site Limitations
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Double Geomembrane Liner System
Soil/Cement Layer Protective Soil Layer Leak Detection System 80-mil Primary HDPE Geomembrane 80-mil Secondary HDPE Geomembrane GCL or Low Permeability Sub-base
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Proposed Expansion of Coal Combustion Waste Area Runoff Pond
SOUTH NORTH ELEVATION 89’ TOP OF HDPE LINER MAX OPERATING WATER LEVEL MUST TREAT/TRANSFER WATER LEVEL MAY TREAT/TRANSFER WATER LEVEL MIN OPERATING WATER LEVEL DOUBLE LINER SYSTEM NEW UNDERDRAIN SYSTEM SOIL COVER WITH 8-INCH THICK SOIL-CEMENT SURFACE
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SOIL-BENTONITE CUT-OFF WALL
Soil-Bentonite Cut-off Wall Option SOUTH NORTH ELEVATION 89’ DOUBLE LINER SYSTEM NEW UNDERDRAIN SYSTEM SOIL COVER WITH 8-INCH THICK SOIL-CEMENT SURFACE SOIL-BENTONITE CUT-OFF WALL EXISTING CLAY LAYER
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Subsurface Soil Conditions
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Finalize Design Prepare Detailed Design Drawings
Prepare Specifications Provide Regulatory and Permitting Support Provide Construction QA/QC Services
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Modification Costs Landfill Expansion $14,175,000
Pond Modification $ 5,675,000 Bentonite Wall $ 1,930,000
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Questions?
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