This project involves the closure and capping of a landfill that has been operating for several years. Due to adopting a simplistic filling method during construction, significant volumes of leachate are generated during heavy rainfall and flood periods, leading to the discharge of leachate and causing severe pollution to the surrounding environment.
Project Overview
The landfill was constructed and operated early on, with low construction standards and open waste dumping.
Following the decommissioning of this landfill, a soil cover has been applied, and a 12m high wall has been erected outside the waste disposal area. Additionally, a leachate pond has been constructed, measuring 30m in length, 20m in width, and 5m in-depth, with a capacity to hold 3000m³ of leachate.
As per the investigation, the landfill covers an area of approximately 40,000㎡, with an estimated waste volume of around 800,000m³. The landfill was created using a simple dumping method without proper sealing measures, making it a historically non-compliant landfill site.
Due to the limited capacity of the leachate treatment facility at the landfill, a significant amount of leachate is generated during heavy rainfall and flood periods. This leads to leachate discharge, causing severe pollution to the surrounding environment.
Solution
To effectively contain the local landfill pollution source, several measures have been implemented:
Hardening and Horizontal Sealing of the Landfill Cover:
The landfill cover has been hardened, and a horizontal impermeable layer has been added.
Construction of Underground HDPE Geomembrane Flexible Vertical Sealing Curtains:
Flexible vertical impermeable curtains made of HDPE geomembrane have been constructed with a groove depth of approximately 15m. This three-dimensional approach aims to block the pollution source, creating relatively independent hydrogeological conditions within the site to prevent the further spread of pollutants.
For the vertical impermeable layer, a smooth-faced geomembrane with a thickness of 3.0mm and an area of 5600㎡ has been used. For the horizontal impermeable layer (secondary spray with roughening), a double-rough-faced geomembrane with a thickness of 1.5mm and an area of approximately 37,500㎡ has been employed. The connection lock has a length of about 6840LM.
The project has employed HDPE flexible vertical impermeable wall barrier technology, effectively addressing the spread of the pollution source. This approach eliminates safety hazards related to further pollution of the surrounding agricultural environment, achieving the desired remediation effect.
Conclusion
The treatment process for leachate in landfill disposal involves two main approaches:
- Measures have been taken to strengthen the landfill cover, control pollution sources, and cut off their groundwater and surface water supply sources.
- Vertical impermeable curtains have been constructed underground to isolate pollution sources and control the overall water quality of surrounding water bodies.
Through the implementation of these measures, the leachate has been effectively treated to meet emission standards, ultimately achieving the goal of reducing environmental pollution.
