Underground Drain Installation in Reigate Using Directional Drilling for a Trenchless Drain Installation
A complex trenchless drainage installation over 60 meters with a steep fall
Challenge
Our client approached us because they were struggling with a solution for underground drain installation for a new build property. An extremely complex site needed specialist trenchless drainage installation solutions – in particular to deal with the steep incline and the severe chalk and flint ground conditions.
Drilling
A trenchless drainage installation was specified by the architect (Reigate Architects) because of extremely restrictive site access, and the fact that the road to the site needed to remain open for other residents. Precise planning was required from the architect for every aspect of the build.
“We gave Mole a challenge in lots of different ways. A steep slope with difficult access that meant we couldn’t use a large rig, a relatively hard material (chalk) and a 70m distance. With some help from our groundworks contractor and architect and a lot of hard work all round, they made it! As a result we avoided installing a septic tank, which would have required lots of permits due to the environmentally sensitive nature of the area, and avoided the associated high ongoing maintenance costs. Every time I use bleach to clean the toilet I will be grateful that the connection went in. I called Mole on the off chance they could help us, not really imagining that the connection would be achievable. But they were happy to talk with me as a non specialist, explain the process and risks clearly to us. This can do attitude and willingness to consider a tricky project isn’t found everywhere. They were great at engaging with us on all the paperwork and permits required and liaising with the other professionals on the project.”
On site: The Mole Utilities team provided an initial estimate based on a remote survey of the location and ground conditions, and followed up by several onsite surveys by our senior engineers. The ground conditions (chalk and flint) and extremely steep incline over the drilling run (a fall of 30 – 40%) made this project extremely technically challenging. A fall of this magnitude is much higher than directional drilling is typically specified for, making this underground drainage installation high risk and requiring a high level of drilling expertise. However, our specialist underground drain installers were confident and once planning permissions were in place and the foundations were dug, they were ready for the drilling to begin.
Completion: The underground drain installers successfully and quickly drilled 60m of 110mm drain pipe to schedule with minor issues caused by access, ground conditions and fall quickly resolved on site. The team were able to drill accurately to where the drainage connection was required, ready for the accuracy ready for the connection to be made by our subcontracted drainage connection company.
Over the past year, we have developed a good working relationship with the customer and are very excited to see the finished project!