Safe landfill capping with Bentofix®
Beneficial reuse: from landfill to a country park
The seaside town of Grimsby is located in the northeast of England, situated on the south side of the Humber Estuary. Grimsby is famous for its fishing heritage and remains today an important fish and food processing centre. The town also boasts a thriving chemical and gas power industry.
In 2013, the North East Lincolnshire Planning Committee approved the application by landowner Millennium Park to decontaminate a 23.7-hectare former landfill site and convert it into an exemplary, beneficial reuse project: a country park.
The development, located in the centrally located West Marsh area of Grimsby, promised 23 hectares of parks, wild life zones, fountains, children’s play areas, and open spaces.
Remediation work started in November 2014.
NAUE worked closely with design engineers Grontmij in advising an optimum Bentofix® GCL capping system. Due to the end use being a recreational area, it was important to make sure the capping system was robust, flexible, self-sealing and a proven gas barrier and low permeability barrier to infiltration of water. Also, the beneficial reuse of the site and the enhanced protections that came with that approval meant that multiple types of GCLs were specified. Each type was selected according to the specific zone’s design and functional needs.
For 6.5 hectares of the site, Bentofix® BFG 5000 was installed to secure the land on which the main recreation facilities would be constructed. All Bentofix® products contain high-swelling, high-quality powdered sodium bentonite and are manufactured with needlepunch and Thermal Lock (enhanced shear strength) technologies; but Bentofix® BFG 5000 was specified for the recreational facility area for its complete impregnation of bentonite in the nonwoven geotextile, its self-sealing overlaps to ensure a continuous barrier and its independent BBA Certification for waterproofing and methane/ radon barrier performance under confining pressure.
For 16.5 hectares, Bentofix® X2 NSP 4900, was used as the low permeability capping system. Bentofix® X, which has a special polymeric coating installed facing up, was specifically chosen for this application due its heightened performance against desiccation (which enables a hydrated, restoration soil depth of 450mm), its protection against ion exchange, its root barrier performance and its higher gas barrier characteristics.
An additional benefit of the polymeric coating is that it is extruded onto the GCL, so there is no risk of the critical polymer layer delaminating (Some products use glues instead of extrusion).
This was an important advantage for the Grimsby site. It offered extra assurance for the environmental protection plan.
Selecting different types of GCLs for specific roles within a design, rather than simply selecting a single barrier, may seem costly because each product is used in a lower volume; but, it isn’t really. Specifying based on unique needs at particular project zones ultimately makes for a more precise, cost-efficient project up front and in the long term, as each material performs exactly to the barrier needs where it has been installed. This takes place of other measures that may be needed to make a less-specific barrier system work where it is not ideal.
Also, NAUE’s strength in logistics and client communication yielded savings, as the rolls of Bentofix® were delivered to the site on time, per the main contractor Bay Construct’s delivery specifications. The project works were able to unfold as planned and site costs were controlled. This made all parties involved in the construction and installation phase happy.
Further adding value to the project, NAUE provided quality assurance support, installation details, tie-in details, and subgrade cover soil compatibility testing.
All materials were independently tested by a third-party laboratory in accordance with the requirements of the government regulator in England, the Environment Agency.
The Bentofix® GCL capping work has been fully completed, and as this issue of NAUE News goes to press, the country park continues to take shape in Grimsby’s city centre.