10 April 2019

Derby Underground Mine Finale

Panoramic view of roof fall

I promise this will be the last post on the Derby Mine (at least for a while). We are about to move out to New Mexico for work, so I don't anticipate getting back to Derby any time soon. This time, our main goal was to completely map the accessible underground workings.

Floating haul truck tire
Using a laser measuring device, I was able to determine that both rooms and pillars average 35-40ft across, while the back is around 18ft tall. The relatively shallow depth of the Derby mine eliminates the requirement for colossal pillars to support the column of rock above the mine. The extraction ratio at Derby was probably near to 75%, which is quite excellent.

Truck used to transport explosives
This truck looks to have been parked for quite some time.
Mostly-blind mine turtle
The Derby Mine has a decent population of frogs and turtles. The turtles seem to be mostly blind from living underground for generations.
The worst roof fall I've ever seen

Reports indicate that the Derby Mine shut down around 1983 after a serious roof fall. I believe this may be the roof fall in question, but it's very possible that more falls exist in the flooded portion of the mine. Fortunately, no injuries or loss of life resulted from this roof fall - based on the muckpile in the back of this heading, I think the roof came down about the same time as the heading was shot.

Map of Accessible Underground Workings - Derby Underground Mine
There is doubtlessly more to the Derby mine than we could access. A raft or small boat is needed to access the flooded workings.


08 April 2019

Green Million Extension Mine No. 1

A few months ago, we drove out to the Central Kentucky Mineral District to chase down a couple of mines that had confirmed underground access as of the 1990s. Actually finding them was a colossal pain, and honestly took more luck than anything - MRDS is essentially useless in the CKY district since the data is woefully incomplete. I relied on old documents with vague descriptions of mine locations, and spent several hours in Google Earth until I found an apparent waste dump that roughly corresponded with a published location, and lined up with a mine symbol on an older 1:24,000 topo map. Even more Google-fu gave me a possible owner name and a phone number.

Success! I found the right guy, and managed to get permission to photograph the mines, both of which are on his property. He's had problems with trespassers, so exact locations will not be shared. We'll just call this mine the Green Million Extension No. 1. It produced high-grade calcite, though tonnages and production dates do not seem to have been published.

Adit at Green Million Extension No. 1
The adit at the No. 1 mine has definitely seen better days, but is still sufficiently open. Rail and pipes outside the adit show that compressed air drills were used, and ore and waste were hauled out via ore car. The track looks to have forked outside the portal, with one track running to a waste dump, and the other running to a pile of good-quality calcite ore. I presume the ore would have been trucked to a nearby mill. A vertical shaft is located outside the adit, in line with the vein. A set of foundations nearby probably belonged to an engine/hoist house.

Mine rail in good condition
I was pleasantly surprised by the condition of the mine rail once we crawled inside. This mine is quite damp; the amount of groundwater makes it seem like it's raining in places.

Stope and fallen timbers
The vein in this mine is oriented vertically, or so near to vertical that it makes no difference. Stull stoping techniques were used, and planks were placed between stulls to provide a working platform for the miners. Old-school hard rock mining at its finest - most mines like this in Kentucky are underwater in the western fluorspar district.
A better view of a stull stope in the Green Million Extension No. 1

Flooded winze
Unfortunately, we were unable to reach the end of the drift. The timbers in this flooded winze don't look especially trustworthy, and I didn't feel like getting wetter than I already was at the time. When this photo was taken, I was standing at the bottom of a collapsed stope and my bibs were nearly soaked through with groundwater. It wasn't warm water, either!

Collapse to surface
The miners mined close enough to the surface to trigger a collapse; there was a pile of rock and dirt four or five feet high in the drift. If the pile had been mucked out, I would have assumed the opening to be deliberate, and intended for ventilation.

I was told by the mine owner that there is a dead cow on the crown pillar at the bottom of the photo above - it fell in from the surface!

Surface Map - Green Million Extension No. 1 Mine
Cross-section of Underground Workings - Green Million Extension No. 1 Mine
In order to best communicate the arrangement of surface and underground mine features here, I've prepared the above two drawings. I speculate that a lower level exists directly beneath the upper level, connected to the winze and vertical shaft. This level was likely extensively stoped, with ore and waste hoisted out via the vertical shaft.












Derby Underground Mine Finale

Panoramic view of roof fall I promise this will be the last post on the Derby Mine (at least for a while). We are about to move out to...