DIRECTIONAL DRILLING was used to install three horizontal drains under Rainham Landfill in Essex last month, in what is believed to be the first application of its type in the UK.
The work is part of a research project investigating more efficient methods of controlling leachate in old landfills.
Southampton University's department of civil and environmental engineering is running the project in collaboration with waste management operator Cleanaway.
The longest of the three drains is 250m, and was installed by contractor DrillTec using a 100t directional drilling rig.
Instrumentation, including pore pressure transducers and magnetic extensometer settlement gauges, has been installed around each drain to monitor its effect on the surrounding waste and leachate levels.
'Dewatering of landfills using horizontal dewatering systems is a proven technology, ' explains Cleanaway's operational environmental systems manager Darren Cole.
'However installation of horizontal drains can be very difficult and expensive but after two years' research an appropriate drilling technique using overwash drilling has been applied successfully.'
No pumping of the leachate wells has yet been undertaken, but provisional indications indicate that the well yields will be high, Cole predicts.