twitter instagram linkedin linkedin
carbon neutral
X close

Who we are

Cognition is a Tier 2 multidisciplinary contractor equipped for it all, from routine works to major infrastructure projects. We deliver innovative, sustainable solutions across the full project lifecycle — from early contractor involvement (ECI) and planning through to delivery. We can solve all civil engineering and remediation problems, helping unlock sites and drive regeneration for our clients.
X close

What we do

We offer our clients comprehensive solutions, providing a wide range of services from civil engineering, to enabling, remediation, earthworks and groundworks. We have the necessary skills and experience to solve your ground engineering challenges and we offer innovative solutions to save time and money.
curve

News

header example
downarrow

Progress Update: Keighley Gas Holder No. 2 DNAPL Remediation

27 April 2026

Cognition Land & Water have been appointed to deliver Dense Non-Aqueous Phase Liquid (DNAPL) removal works at the former Keighley Gas Holder No. 2 site for Northern Gas Networks. The objective is to safely recover DNAPL contamination from the gasholder structure, in line with the project remediation specification and strict HSEQ standards. The works form part of a wider programme to manage legacy contamination at former gasworks sites, protecting the environment and enabling future land use.

Key constraints on this project include:

  • Large volume of DNAPL contamination present within the Gasholder
  • Requirement to work within an operational gas infrastructure environment
  • Need to minimise environmental impacts such as noise, dust and odour
  • Strict regulatory and safety controls, including permit-to-work systems
  • Variable DNAPL viscosity requiring adaptable recovery methods

The remediation programme included:

  • Site mobilisation and compound setup
  • Installation of six supplementary abstraction wells
  • Installation and operation of the FABEX system to target and recover NAPL without the need to pump and treat large volumes of water
  • Recovery potential tests using fabric extraction system to determine the mobility and recoverability of the NAPL
  • NAPL recovery data presented in site clearance/verification reporting
  • Environmental monitoring to ensure nuisance odours did not impact local residents
  • Groundwater monitoring and chemical testing to confirm completion of remediation objectives
  • DNAPL recovery from a total of nine abstraction wells
  • Storage, separation and off-site disposal of DNAPL
  • Weekly monitoring and reporting of DNAPL thickness and recovery rates

Cognition’s NAPL Fabric Extraction Systems (FABEX) treatment method is significantly more cost-effective than conventional techniques for the remediation of NAPL. By targeting NAPL it eliminates the need to remove vast quantities of groundwater. It works by drawing NAPL from the groundwater using a hydrophobic/oleophilic fabric on a continuous motorised loop (pulley system). The NAPL is then desorbed from the fabric by squeeze rollers and drained into containers prior to off-site disposal. This treatment method as many benefits including eliminating the need to pump & treat groundwater, it recovers LNAPL & DNAPL from contaminated groundwater direct from wells and it is significantly cheaper than conventional remediation techniques on a project lifecycle basis.

Cognition have successfully recovered 89m3 of DNAPL so far with almost no water in 7.5 months using the FABEX system!

If you would like to find out more about the benefits of our FABEX system, please visit the following link:

https://www.cognitionlandandwater.com/news/388/142/FabEx-Innovative-and-Efficient-Free-Product-NAPL-Removal/ 

Fabeex small.jpg
small transparent gif for site construction purposes