LFP Landfill - Whinney Hill - LFP Environmental Group

LFP Landfill – Whinney Hill

Whinney Hill Landfill, Lancashire, North West England

The Story

We were appointed to deliver a temporary and permanent capping system at the largest landfill site in the North West, Whinney Hill. This would protect the site and prevent contamination caused by landfill gas egress and the infiltration of water, in turn creating leachate.

Strategy

The process involved the general trim of waste through surface regrade ready for the placement of a 300mm thick regulating layer to smooth out the surface and achieve liner formation levels. This was the first step in achieving the formation levels for the liner.

The team laid out and fully welded, 1mm thick, double textured geomembrane. This comprised of both linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) geomembrane. It was installed over the regulated surface tying into the current lining system to help maximise the reuse of the site’s existing materials and infrastructure. This is a stage that is vital to building our sustainably focused ethos in the project’s DNA.

Over the newly installed capping geomembrane, our team then added a protective geotextile. This helps to separate different types of soil whilst its porous materials allow water to travel between the layers. The team ran a stability analysis which, together with engineering specifications, indicated the requirement for a drainage geocomposite (GDL) to be installed.

In order to protect the exposed geomembrane covers against adverse weather conditions causing wind damage and displacement, a net down system was installed. This defuses wind flows, avoiding any potential health and safety incidents. Above the net down system, the team installed 1000mm of restoration soils. As the finishing touch to restoring the land, these soils will ensure growth of vegetation, reduce rainfall infiltration, mitigate soil erosion and improve the overall ecological diversity.

Key Highlights

• Installed geomembrane tying into the current lining system to reuse the site’s existing materials
• Restoration of soils above the geotextile to improve ecological diversity
• Welding and jointing membranes in an environmentally friendly way

Solutions

The main challenge presented in this project was the design of a system that would prevent gas and leachate leakage from the landfill site. This required novel techniques to combine different membrane systems that would work to protect and restore the land. The team was successful in joining the varied materials together, forming the capping membrane to prevent contamination to the ground. This incorporated a drainage geocomposite to enable effective drainage within the restoration soils.

A variety of welding techniques and construction methods which had not previously been installed in this manner were used at this location. This assisted development of an overall installation methodology which passed construction quality assurance requirements and delivered the design objectives. In addition, our learnings in welding and jointing membranes with the ability to deploy these techniques at other locations is a win for environmental sustainability nationwide.