Old wells


Foundations near old wells


Foundations near old wells

If there is an old well or soft water store near your new foundation, the main concern is that any future deterioration of the well will lead to the migration of the surrounding soil into the well, which could result in foundation subsidence. Therefore foundations near old wells need to be designed to take this into account.

The simplest solution is often to fill the well with concrete to prevent this happening.  However, if the old well has alreadt been partly filled it is often not possible to do this.  A partly filled well is likely to have a high proportion of voids, unless it was filled properly.  If the well is filled, the new foundation shouldn’t sit directly on top of the concrete. There needs to be a layer of compressible material between the new foundation and the infilled well.  This is to prevent creating a hard spot which will lead to cracking in the building as it settles.  The foundations needs to be designed to span over the compressible material.

If the well cannot be filled then the best solution is to reinforce the foundations so that they can span over the well, far enough so that any future subsidence of the ground adjacent to the well will not affect the foundations or the building.

This type of problem is often only discovered when the excavation for the foundations starts on site. Therefore a quick solution is required.

Our designs normally result in only a very small increase in the construction cost.

We need the following information to design foundations near old wells

architectural layouts or sketch drawings with dimensions of the building / extension showing the position of the foundations in relation to the well

the location, diameter and depth of the well

Design information

All designs are carried out in accordance with BS 8110 and BS 8004:1986

You should satisfy yourself that the excavation for the foundations will not undermine any adjacent foundations or neighbouring ground

Excavations may fall under the Party Wall Act Please seek specialist advice.