In-situ Lining of Ash Basins via Segmented Cell Construction
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Solution Overview
Problem
Existing methods for addressing contaminated ash basins and landfills, such as excavation and transportation, capping, or constructing new lined sites, face challenges like high costs, regulatory hurdles, and environmental risks, and do not effectively prevent groundwater contamination.
Innovation Solution
A method involving the division of disposal sites into cells, installation of perimeter and interior barrier walls, transfer of waste to form empty cells, removal of contaminated material, and in-situ lining with a barrier liner layer to create lined cells without relocating waste, using engineering and construction techniques to manage the site's geometry and soil conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excavation and transportation of ash is performed to relocate it to a lined landfill, then the ash disposal site can be cleaned up, but high transportation costs and environmental risks from spills occur
Solution Approach 1:
The ash basin is divided into multiple cells by installing interior barrier walls, allowing selective access to different sections. This segmentation enables lining operations in isolated cells without requiring complete ash removal, thereby eliminating the need for expensive and risky transportation while still achieving groundwater protection goals.
Solution Approach 2:
Barrier walls and liners are installed in advance within the ash basin to create isolated lined cells before any ash removal or relocation occurs. This preliminary action establishes protective measures in situ, preventing the need for subsequent transportation and eliminating associated environmental risks.
2Reliability
If a new lined ash basin is constructed at the power plant site, then groundwater contamination is prevented, but land acquisition and regulatory permits are required
Solution Approach 1:
The existing ash basin is segmented into multiple cells using interior barrier walls, allowing portions of the basin to be lined and isolated without requiring complete reconstruction or new land acquisition. This reduces regulatory complexity by working within the existing site boundaries.
Solution Approach 2:
Liners and barrier walls are preliminarily installed within the existing ash basin structure, creating lined cells in place. This approach utilizes the existing land footprint and avoids the complex regulatory process of acquiring new land and obtaining permits for a completely new facility.
3Object-affected harmful factors
If the ash basin is capped in place, then rainwater input is eliminated, but groundwater flow through the ash remains uncontrollable
Solution Approach 1:
The ash basin is divided into isolated cells by interior barrier walls, allowing specific cells to be lined and sealed off. This segmentation enables control over groundwater flow paths within individual cells while maintaining the ability to address rainwater input through targeted capping of specific areas.
Solution Approach 2:
Liners are preliminarily installed within isolated cells before capping operations. This preliminary lining ensures that when caps are placed, the underlying groundwater flow paths are already controlled, preventing contamination even as rainwater management is implemented.
4Ease of manufacture
If ash is pushed to expose native soil for liner installation, then lining can be performed, but wet ash behaves like liquid mud and continuously falls back
Solution Approach 1:
The ash basin is divided into cells with defined boundaries created by barrier walls. This segmentation allows for controlled access to specific areas for liner installation without requiring large-scale ash movement. The confined cell structure provides stability during liner installation operations.
Solution Approach 2:
Barrier walls are preliminarily installed to create confined cells before any ash redistribution or liner installation occurs. This preliminary structuring provides stable boundaries that prevent wet ash from flowing back, creating a controlled environment for subsequent liner installation without requiring ash to be pushed or exposed.
Data Source
AI summary
A method for lining an existing waste disposal site having a waste level includes, for example: installing perimeter barrier walls about the site and interior barrier walls within the perimeter barrier walls to define cells; transferring waste, such as for example ash, from one of the cells to one or more other cells to form an empty cell with a layer of contaminated material at the bottom of the empty cell; removing the layer of contaminated material from the empty cell to form a clean cell with a noncontaminated bottom layer; installing a barrier liner layer in the clean cell to form a lined cell; and transferring waste from other cells into the lined cell.