Phase SI were recently called in to help resolve the slightly unusual problem of a missing well!
A large Victorian industrial complex was being redeveloped and it was known that a well was present under one of the buildings. Records indicated that the well had been capped and then covered by the current concrete floor but the only record of its position was a sketch plan which was referenced to internal walls that were no longer present!
The well needed locating so that the shaft could be examined and a new cap put on to ensure that it was safe and also that there would be no risk of contaminating the water table during the redevelopment. The well is now located under a building and so carrying out an excavation to locate it would be relatively difficult as well as potentially creating a contaminant pathway if the cap was damaged.
Phase SI were called in to carry out an non-intrusive survey. Ground penetrating radar (GPR) was ideal for this survey as it is not affected by above ground buildings and is a relatively manoeuvrable system. Two rooms were scanned using the GPR and within 30 minutes a buried area of ‘rebar’ was identified. Detailed scans around this area confirmed the presence of a 1.0 m square reinforced slab at a depth of 0.2 m to 0.3 m. The position and extent of the feature were marked out on site.
The remainder of the survey area was scanned and no other features suggestive of a well or cap were identified. The GPR anomaly could be interpreted as the well cap with a high degree of confidence, particularity given the lack of other features or variations, and the subsequent removal of the floor slab in this area confirmed this.
Geophysics provided a rapid, safe and cost-effective solution to the slightly unusual problem of locating a buried well.