Talla Reservoir and Dam

In the 1890’s a need to expand the water supply to Edinburgh was identified. The site at Talla Loch, some 28 miles south of Edinburgh was selected for development.

Starting in 1895 the project included building a rail link for the transport of material and construction ran from 1897 to 1905 when the reservoir was officially opened. The design included an embankment type dam using Puddle Clay as the water barrier.

In 2008 Robertson Geo were contracted in to collect images of the interior of the dam and associated brickworks. Some 59 boreholes were drilled, many at shallow inclinations and a CCTV camera with side and front imaging capability was deployed to record the condition of the internal structures.

Five years later Robertson Geo were again contracted in to provide information on some specific points of interest within the brickworks. Three horizontal boreholes up to 7m in length were drilled and a High Resolution Optical Televiewer (Hi-OPTV) deployed to capture an unwrapped image of the borehole wall. As the boreholes were underground at a remote distance, portable equipment was deployed via the control tower and wheeled several hundred metres into position on a bogey. The information collected was vital for ascertaining the condition of the brickwork and stonework after more than a century and to delineate the internal cavities.