The Trethewey Pit is located on private land. It produces 25 millimetres Well Graded Base from an outwash deposit. Technical data: Pit run; 3 per cent fines, 12 per cent sand, 10 per cent fine gravel, 7 per cent coarse gravel. Petrography of the aggregate from the pit is derived from 43 per cent igneous and volcanics, 30 per cent granodiorite, 27 per cent feldspar porphyry.