Case Studies

Repairing a collapsed borehole

Published:

We repaired a collapsed borehole for a textile company near Mansfield. Our investigation showed that the borehole wall had collapsed at depth, possibly caused by ground movements due to historical coal mining activities in the area.

About the collapsed commercial borehole:

760mm diameter to 85m deep
Cased to 28m with steel casing – open hole below
Pumping rates of 56m3/hr
Geology: Sherwood Sandstone

The problem encountered:

The main issue was dirty water being encountered during borehole pumping.

Investigation by WB+AB Morgan using CCTV showed that the borehole wall had collapsed at depth, possibly caused by ground movements due to historical coal mining activities in the area.

How we repaired a collapsed water borehole:

  • We removed the existing pump and old steel riser pipe
  • Then we cleared the borehole using airlift eductor technique
  • Our team installed a new casing string using Bridge Slot Carbon steel screens at 406mm
  • And they installed 3-8mm gravel pack to stabilise the borehole wall
  • We developed the borehole using airlift to settle gravel pack
  • Then a new pump on new PVC rising main was installed
  • Finally, the team carried out a step test to check borehole performance.

Now the water runs clear after the borehole pump is turned on – and a pumping rate of 60m3/hr with minimal drawdown shows that the borehole is still hydraulically efficient.

Bridge slot screens

Image: Bridge Slot Screens

Many commercial companies - from farmers to factories, from golf courses to global drinks producers - rely on their own boreholes. If you have an underperforming or blocked borehole affecting your company, call us for an immediate and comprehensive response.

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