Construction engineering expert Holemasters was contracted by geotechnical specialists BAM Ritchies to strengthen the dam walls of Seathwaite Tarn, a distinctive and outstanding feature in the Lake District, Cumbria, using specialist Diamond Drilling techniques

This gravity dam, opened in 1907, is a gentle arc 138m long and 9m high, situated just outside the original margin of the tarn. It is composite in construction being formed of a concrete gravity section on the right side (north) and an embankment section on the left side (south) with a concrete core. The dam is entirely solid, with no internal walk-way.
Seathwaite Tarn is a reservoir that provides drinking water for the town of Barrow in Furness Cumbria and is accessed via a service road from the Duddon Valley which is actually for walkers only.

Holemaster’s Project manager, Tony Mason, who works out of the company’s Cumbrian office said: “This project involved the drilling of 37 large diameter holes each 500mm diameter by a depth of 500mm. A ‘top hat’ section measuring 550mm diameter x 50mm deep formed head pits for BAM Ritchies to follow behind and rock drill to a depth of 6mtrs. Reinforcing bars and high strength grout were then inserted as a robust strengthening method.


“In addition to this we were required to carry out 37 passive drainage holes which were 50mm diameter x 1500mm deep.
“The difficulty with this particular project was firstly the location, this being in the Cumbrian Fells where access to the actual works could only be achieved by the use of a 4×4 vehicle.

“Secondly, as this project was carried out in November we had a daily battle with the elements and our operatives had to work in what I can only describe as horrendous conditions.
“However, despite all of this, the project was brought to a successful conclusion within time and budget and to the delight of our client.”