Dyffryn adda drainage adit
|In 2001 the group decided to explore an old drainage adit to the North East
of the mountain. The adit had not been entered for about 40 years. The flow
of water out from the adit was very slow due to the build up of "Ochre" a
thick mud formed by the oxidation of iron.The joint level at Dyffryn Adda was driven for 3000 feet into the mountain
by the Parys and Mona mine companies around 1850 to help dewater the mines
below the 45 fathom level.
||Once the entrance had been cleared it was possible to wade through the thick mud and water. .|
|In the 19th century, when
deep mining had ceased , a dam was constructed across the level to allow the
stoops and levels in the mountain to flood up to the 25 fathom level of the
mine. This allowed many millions of gallons of water to pond up behind the
dam and absorb the copper minerals remaining in the worked out mineral
veins. After many weeks work we where able to find the dame again. The
concrete and valves were in a very poor state of repair.
It was immediately realised that the hold up of water behind the rotting dam was a great hazard to the people of Amlwch. A dewatering project was set up to try and deal with the problem.