Talla Reservoir, Dam

NT12SW 17.01 10451 22820 to 10740 22891

The dam (which has also been termed an embankment) measures up to 600ft (183m) across the base, 20ft (6.1m) across the top, and 350yds (320m) in length. It is of earth construction, being built around a core of clay brought from Carluke (NS c. 84 50) and subsequently 'puddled'; this was put in place by a 'Blondin' or overhead carrier. About 5500 tons (559t) of squared pitching stones were brought from Craigleith Quarry (NT27SW 168) and North Queensferry [name: NT 12 80], and set on the embankment, extending from the top to about 10ft (3m) below top-water level, as a protection against wave action. Rubble pitching was laid at a lower level, being mostly brought from a quarry (NT12SW 36) alongside the railway and nearly opposite Tweedsmuir parish church (NT12SW 2.00). Between the rubble pitching and the toe of the embankment, its face was covered with 'beaching' of broken stones. Apart from the 'puddle' wall and the stone, all the material used in the construction of the dam was derived from within the reservoir, thus adding to its capacity.

A line of cast iron pipes of 36ins (0.91m) diameter carries thewater into the measuring house (NT12SW 17.06) through a tunnel 400yds (366m) long driven through the rock of the hillside near the E end of the dam.

The waste water weir and channel are situated at the E end of the dam. The former measures 200ft (61m) across at the top, and gradually narrows to a width of 40ft (12m). About 350 tons (355t) of Shap granite and 3500 tons (3550) of squared whinstone were used in its construction.

The waste weir channel and the outlet tunnel join the old course of the Talla Water below the dam, where a test basin has been constructed so that the quantity of water being sent down may be checked at any time by direct measurement.

As many as 550 men were employed at any one time on the construction of the dam.

W A Tait 1905.