Vague earthworks mark the line of the shafts along the Herward Vein. The main mine workings and potential processing site were located to the west of the Holywell-Halkyn Road, near a junction with a lane leading to Dolphin. This area has since been cleared, but it is believed to have been the site of the Herward Engine Shaft.

The Herward Vein, located south of Pen-y-pylle Common, ran east to west and was cut to the south-west by the A55. Historical records from the County Record Office in Hawarden mention a 70-inch pumping engine in operation at the Herward shaft in 1833. The Herward United company reporting activity between 1855 and 1865. In 1904, the Sea-Level Tunnel reached the Herward workings, and the mine continued operations until 1912. Later, the Herward mine became part of the Milwr Group.