The road up Castle Hill was closed to traffic on about 12 March 1942 to ensure the construction of military facilities such as this bunker were not obvious. The bunker was completed about 12 weeks later. The bunker was fully air-conditioned during its use in World War II.
There were 17 buildings at Project 81 as follows:-
It is believed that the bunker was used as No. 24 Squadron RAAF Headquarters and by the RAAF Operations and Signals group (Intelligence). The building (120 ft x 60 ft) was built like a fortress, with enormous thick walls and roof. It was apparently capable of sustaining a direct hit with minimal damage.
The rooms in the bunkers were used as follows:-
Two other rooms separated by a walkway were:-
600 cubic yards of concrete and 50 tons of reinforcing steel was used to construct the Green Street bunker.
Four timber buildings were located nearby and one was located on top of the bunker to give it the appearance of a domestic residence from an enemy aerial view. The bunker was well camouflaged and camouflage netting would have been attached from the roofline of the bunker.
The bunker also had its own very large electricity generating plant. A small separate building at the end of the bunker and adjacent to the Generator room, housed the air conditioning plant. It had a sunken floor and you would walk down a small flight of stairs into the room.
WAAAF Helen Ena Suttie worked in the W/T Station, Townsville and 12 Signals Unit in North Eastern Area Command Headquarters in Sturt Street Townsville. On a few occasions Helen was taken by tender on duty to a secret abode (possibly the Green Street bunker).
"The room where I operated the cipher machine also contained a teleprinter which was connected to the main signal station in Townsville. An Air Operators room was adjacent with a hatch between. An aerial photo of this place shows a house with garden gate and fence, a bee hive, looking just like a normal house would look. We worked underground, air conditioned."
Over the years various reports of secret bunkers and tunnels in Castle Hill and Mount Louisa have been received including a tunnel near the Green Street bunker.
Another one of the many rumours about secret tunnels in Castle Hill suggested that there was an entrance in the floor of the Green Street bunker. In 1985 a section of the floor of this bunker was dug up in a forlorn attempt to find the secret tunnel.
Peter DUNN states:
"I have heard many reports that the plant room inside the SES Bunker has a tunnel entrance leading from it. In August 2001, I spoke to a very elderly gentleman who was a foreman with the Civil Construction Corps in Townsville during WW2. He claimed that he had been in the underground part of the Green Street bunker.
I have spoken to another ex RAAF person in late April 2001 who was part of a group inspecting RAAF assets in 1958. His work mate, who was inspecting the Ramsay Street Bunker indicated to him that he had seen a concrete lined underground tunnel at the Ramsay Street bunker heading towards Castle Hill. I have heard other unsubstantiated "stories" of a tunnel connecting the Green Street bunker and the Ramsay Street Bunker.
In April 2003, I met an old acquaintance from my Air Training Corps (ATC) days with No. 1 Flight at Garbutt Air Base in Townsville. He told me that the ATC were considering taking over the Green Street bunker back in the 60's or 70's. It never went ahead, but he told me that there was an underground section of the bunker, which he thought was under the generator room".
Finally in late March 2001, I received information from an ex RAAF member regarding the location of an old WW2 Command Center that he had inspected inside Castle Hill in 1958 beside the Green Street Bunker.
I received a phone call from Wal Moore, Caloundra of 36 Squadron RAAF on 25 July 2001. Wal told me that he went for an interview with North East Area Headquarters at a site in Sidney Street, West End. He said it was a very well camouflaged and secret location. Wal's wife, Fay, was a WAAAF who was living at the WAAAF barracks in Anne Street, Aitkenvale and was taken daily with a cook to the Officer's Mess near the Sidney Street bunker. Fay advised that the bunker at Sidney Street was a Signal Station for North East Area HQ. She also advised that the Headquarters for the Signal Station was located nearby, camouflaged into the side of Castle Hill. Fay's recollection from almost 60 years ago was that this HQ was about 1/4 of a mile up the slopes of Castle Hill and slightly more towards the Belgian Gardens side of the hill.
The Townsville City Council purchased the Green Street bunker from the Department of Defence in about October 2001 for $50,000. In March 2001, the Townsville and Thuringowa Councils approved a joint 5 year plan for a $839,000 upgrade of the old bunker. This included repairs to the leaking roof, internal and external renovations, painting, new carports and the installation of a new generator. This was an initiative of the Townsville and Thuringowa Counter Disaster Committee. The Townsville Amateur Radio Club have occupied the upstairs section for many years.
The Commonwealth Government hired a some premises at 63 Stagpole Street in West End that were possible used for NCO quarters. The sites of 35 and 33 Stagpole St was possible used as Officers quarters and mess.
A bunker of identical design to the Green St. Bunker, but with an external buttress bomb blast wall was built as the Operations and Signals Building (Message Center) at Ramsay Street in Garbutt. No. 2 US Air Command, possibly under the command of Brigadier General Martin F. Scanlon, USAAF was located in that bunker.