To control under-seepage through the natural foundation below the dam, the Pennines embankments generally constructed a puddle clay-filled cutoff trench in rock directly below the central core.
12.
In a further attempt to prevent water loss, at King's Reach, the section immediately east of Sapperton Tunnel, the canal was lined with concrete rather than puddle clay.
13.
As developed by James Brindley and practiced elsewhere later, puddled clay was used to seal the canal; it brought in with difficulty by cart and took four months to build and cost the Stevenston Coal Company ?857 / 4s.
14.
Gilbert, realising that Brindley had placed too much weight on the sides of the arch, removed the clay and laid layers of straw and freshly puddled clay; when the water was allowed to flow in again the masonry held firm.
15.
The river bed is protected against erosion for a width of upstream by a stone paving laid on a puddle clay blanket to check infiltration, and on the downstream side for the same width by a stone paving having an inverted filter bed underneath, so that any springs that may be caused by the water above the sluices shall not carry sand with them from beneath the paving.
