Siphon drain installation
Siphon drain outlet
Siphon system section
- Client
- Highways Agency
- Consultants
- Mouchel
- Siphon wells contractor
- WJ Groundwater Ltd
- Siphon system supplier
- TP Geo
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A section of the M25 motorway, close to Junction 6, has suffered repeated damage over recent years due to slippage of the natural slope on which it is founded. A slip-plane 200 m long at 8–10 m depth had a history of movement, leading to the need for regular resurfacing of the hard shoulder and nearside lanes of the carriageway. In order to improve the slope stability WJ designed and installed a siphon system to lower the groundwater levels which was a significant driver to the slope movement. The installation comprised of 48 siphon wells at 5 m spacing. The system was constructed in manhole chambers and trenches for frost protection. This scheme achieved a significant reduction in the need and frequency of carriageway resurfacing.
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Key words
- roads, infrastructure, green sand, Gault clay, siphon wells