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Landfill Projects
CLP had been planning this project for some time and had anticipated to the use of at least two rigs to speed the process along. Once the work started however it was apparent, due to the fact we now use one of our mid-sized drilling rigs on these shallower type gas wells, that one rig was easily capable of keeping the project on schedule. 
Viridor needed to remediate some as built leachate chambers on their Beddingham Landfill site but were uncomfortable retro drilling new wells near to the basal liner on such a sensitive site. It was decided to drive specially designed steel casings through the existing chambers using a vibrating percussive technique similar to those used in sheet piling. All four wells were remediated to their original depth without risking a breach of the basal liner.
Biffa required 3 monitoring boreholes to be drilled around their Trecatti Landfill site. A site known for it’s exposure to extreme weather conditions and a reputation for awkward drilling due to the extensive mine workings in the area. The job proved none too straight forward and had to be suspended at one point for extra equipment to be manufactured as our original proposed technique wasn’t too successful. However, everyone involved stuck to the task and the wells were completed successfully before the Autumnal weather could hamper progress further.
Utilising one of Magpie’s three MC3000 drilling rigs, the well was drilled with 450mm barrel auger to 50m, where upon a 406mm plain threaded steel casing was installed. The well was advanced with 350mm barrel auger until basal drainage rock was encountered at the base of the landfill. Depth achieved 74.50m. The secondary 273mm well casing was installed to 74m. Due to the success of the first well, the exercise was repeated and a second identical well drilled and installed. The wells were drilled in two separate phases with a total time on site of three weeks.
WRG were required to install 6 leachate extraction wells to the base of the site at Bubbenhall Landfill. Prior to drilling it was imperative they obtained investigative information as to the base levels. On previously projects they had utilised bespoke Cone Penetration Test (CPT) machines to ascertain the base levels, however these had limited depth capabilities and still required a subsequent mobilisation of a drilling rig to complete the work once the depth was known. To enable WRG to undertake the drilling as well as the investigation we used a sampling probe system which had been developed to find basal drainage layers without piercing membranes. The drilling was carried out to a designated depth then ceased at a “safe” level above the liner. The probing tool was then installed into the drilled well and probed the waste material in 200-300mm increments, whilst taking samples of materials. Once the base layer was intercepted, drilling could continue to the levels ascertained by the probe. Not only did this ensure safe drilling practice avoiding any damage to the base liner, but also had very small financial implications for the client.
We were approached by Biffa to drill 600mm diameter leachate extraction wells to various depths up to 48m. Whilst we would normally advise our clients against attempting these depths at such large diameters, Biffa had already purchased the well liner materials for another drilling contractor who had failed to install the wells. Biffa were aware of our recently purchased MC3000 rigs with 600mm diameter capacity and requested we attempt the scope they required with one of these drilling rigs. We agreed and the project was completed, with 11 leachate extraction wells successfully installed to the sites compliance levels.
With as many as three of Magpie’s rigs on this substantial project, drilling was undertaken using 450mm barrel augers for the installation of 250mm HDPE butt fused welded well liners, incorporating a 315mm perforated telescopic “boot” at the base. The majority of the wells were drilled successfully despite some very difficult drilling conditions. In areas where excessive collapsing was encountered, the client requested the installation of 406mm steel casings to support the wells, to allow for the placement of the permanent HDPE liner.
In late 2001 Magpie Drilling was still a relatively small firm but already starting to build a good reputation for quality and reliability. We were approached by Cleanaway to participate in what was by any scale a massive drilling project. Cleanaway had an agreement in place with the Environment Agency that the gas control system incorporating the gas wells would be operational by April 2002. We were recommended to them as a highly dependable drilling contractor specialising in landfill drilling activities. The work was completed ahead of schedule in March 2002, despite the scope being increased to 690 wells. Since this project Magpie Drilling has become the principal landfill drilling contractor for Cleanaway.
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