This structure was completely below ground with raised entrances level with the surface and was roughly aligned east to west. Both entrances were 40cm above the chamber roof and capped with corrugated iron and concrete. The lip for the concrete cap on the eastern entrance was 5cm deep at the sides and chamber end of the entrance. The lip on the west entrance was 5cm deep at the sides and entrance. The eastern entrance was 6.45m long by 1m wide, the west entrance 6.6m long by 1m wide. Both entrances descended eleven steps to a corridor that was 70cm wide and terminated in an 87cm-deep recess with a centrally-positioned 10cm-diameter exhaust vent. Both had poured concrete floors with five 60cm by 46cm concrete slabs set into them.
The central chamber measured externally 7.4m by 1.85m by 2.45m high with an internal measurement of 1.54m at its widest point. The chamber was of unpainted concrete and had a bench extending along the external wall on either side. These benches were 46cm high by 35cm deep and were formed of the same concrete as the entire structure. Evidence of shuttering is clear, with the construction technique identical to that of shelters F1-F7. Sixteen 60cm by 46cm rectangular slabs extended down the centre of the chamber. Three more exhaust vents were located at equal intervals within the roof.
Both the recess and the internal doorways had the remains of iron hinges and the internal door had the remains of an iron latch, indicating doors were at one time present. Iron hook latches were affixed to the external wall of the entrance approximately 1m off the floor. <1>