An Anon in prior bread posted a photo only. Is there a reason for this drop?
Red Hill Underground
Originally Top Secret, Red Hill’s hidden facility became generally known in the early-1990s, when the facility was declassified.
Prior to the attack on Pearl Harbor all of the Navy’s fuel was stored in unprotected above ground tanks at Pearl Harbor, next to the submarine base.
When RADM Chester Nimitz was Commander of the Bureau of Yards & Docks (in 1940) he wanted the Navy’s 2 ½-year supply of fuel oil protected from aerial attack – existing aboveground unprotected tanks next to the Submarine Base presented a vulnerable enemy target.
Standard practice was to dig a trench and bury the tanks, but this was impractical to store 255-million gallons of fuel oil; here, the Navy’s initial plan was to dig a series of tunnels and insert the tanks
Instead, consulting engineer James P Growden came up with excavating large vertical tank chambers instead of horizontal tunnels. (Nothing like this had ever been attempted before.)
This would increase the volume of material that could be excavated simultaneously and decrease the number of heavy equipment needed for hauling muck. It also decreased the unit cost for rock removal substantially.
Starting the day after Christmas 1940, 20 underground fuel storage tanks were built more that 100-feet below the surface. (The facility was designed as an impenetrable, bombproof reserve of fuel for the military.)
To determine the depth necessary to protect the fuel from Japanese aerial attack, the engineers gathered data from the Army, multiplied it four-fold and rounded the figure off to 100 feet of rock cover.
The attack on Pearl Harbor in 1941 had little effect on the work site – work on the storage facility proceeded virtually without interruption.
Each vertical tank is 100 feet in diameter and 250 feet high, roughly the size of a 20-story building, and lined with quarter-inch steel plates (it has an overall design capacity of 6-million barrels of fuel oil (9.97-billion gallons.))
Dug from the inside, the storage facility is connected with pipes (32-inch-diameter diesel pipe, and 18- and 16-inch jet fuel pipes) and tunnels down to a Pearl Harbor pumping station, more than two-and-a-half miles away.
The tanks were set up in two parallel rows with two main access tunnels, one above the other, bisecting the rows; smaller tunnels branched from these main axis tunnels to the tank cavities.
The upper dome of each fuel chamber was excavated first, starting with a ring tunnel, then working upward, towards the central shaft. They started digging in the upper portion of each tank chamber.
Upon completing the ring tunnel, the miners dug upwards in a hemisphere from all points around the ring, narrowing as they reached the central shaft. As soon as the upper hemisphere was concreted, workers were lowered down the central shaft to begin excavation of the tank chamber.
The miners continued to dig downwards in a cone until they reached the lower hemisphere of the tank chamber; tThe lining for the lower hemisphere was placed similarly to the top.
Then, they steel-lined the walls of the tank chamber. Reinforced concrete was placed against the rock and smooth continuously welded steel plates formed the inner liner. (Rogers)
Think of the scenario: with limited above ground disturbance, hollowing out twenty 20-story building-sized cavities 100-feet underground, lining each with ¼-inch steel (with concrete-backing,) testing and repairing leaks, and tunneling them together and to Pearl Harbor, 2 ½-miles away – in secrecy.
In 1995, the American Society of Civil Engineers placed the facility alongside Hoover Dam, the Eiffel Tower, Panama Canal and Statue of Liberty as a historic landmark.
In 2014, evidence of fuel leakage was noted. The Navy and City & County, State and Federal agencies have come together to evaluate the impact to the environment and community, and to look at solutions in dealing with the leak and strategies to mitigate the impacts.
While at DLNR, I had the opportunity to visit the Red Hill Underground Fuel Storage Facility above Pearl Harbor; it’s a secured facility with no public tours or access.
http://imagesofoldhawaii.com/red-hill-underground/