Corrwg Minewater Treament Scheme

Site History

Glyncorrwg Colliery was opened in 1904 by Glyncorrwg Colliery Company Ltd and later worked by Glyn Neath Collieries Ltd.

It lay in an isolated valley six miles north of Maesteg and at a point near the northern boundary of the No 2 (Maesteg) area. The Colliery was situated about 900 feet above sea level at the head of a narrow valley.  The surface was restricted for space and road access was poor.  

The sinking of the shafts was undertaken by the Glyncorrwg Colliery Company Ltd, and were completed in 1905.  The No 2 Rhondda, Six Feet and Red Vein seams were then worked to a limited extent. 

The Colliery was closed during the period from 1912-1919, and subsequently re-opened but not worked regularly and 1924 the company went into liquidation.  In 1925 the Colliery was acquired by the Vale of Neath Colliery Company Ltd, who were the owners until 1927, after which it was taken over by the Amalgamated Anthracite Company Ltd, under whose control it continued until 1st January 1947.

The Colliery had large reserves of coal within its "take", which varied from Anthracite to dry steam in quality.  The coals to be developed were generally border-line Anthracite, tending to Anthracite in quality, and were suitable for the majority of the requirements for Anthracite in the inland market.

Increased production of these coals  increased the total availability of Anthracite, enabling more of the better grades of fuel to be exported.  The washed duff was suitable for Briquetting, and for use in some power stations.  The area worked lay for the most part to the north east of the Colliery and had been specifically divided into two parts primary development, secondary development. 

Underground the coal was hauled up a drift of 1 in 6 to the pit bottom.  The underground layout  involved a stone drivage intersecting the Six Feet seam and the lower seams.  Staple shafts at intervals of approximately 800 yards and equipped with spiral chutes were used to transport the coal from the seam above to loading points on the stone drivage. 

Diesel locomotives would haul trains of mine cars from loading points direct to the pit bottom.  The Colliery had a rail link for the transport of the proposed output to Cardiff or Swansea. 

The National Coal Board authorised  reconstruction work in the late 1950s to 1960´s.

The reconstruction layout involved extensive pit top re-arrangements, the extension of sidings, the installation of two electrical winders, the installation of a new coal preparation plant, the operation of all fixed plant by electricity, the erection of a new compressor house with new electrically driven compressors, the improvement of road access to the Colliery, the erection of new offices, lamproom, workshops etc, and the provision of an aerial ropeway of 80 tons per hour capacity to tip on high ground.

The National Coal Board closed  the Colliery in May 1970.

Minewater Scheme

The minewater at Corrwg is generally not alkaline, and consists of 3 separate discharges totalling 7.5 litres per second.  The low dissolved oxygen content necessitated the construction of cascade structures between the reedbeds to provide additional aeration of the water.  The total iron content of each of the three discharges carries between 11.5 and 28 mg/litre.

The scheme at Corrwg is a purely passive system, requiring no electro-mechanical intervention to convey the minewater. The scheme treats 3 iron laden discharge.  The 3rd discharge crosses the adjacent river by means of a small bridge. 

The scheme is made up of 11 reedbeds constructed in such a manner as to take advantage of the contours of the narrow valley where the scheme is located.  The reedbeds total 4800m2 in area.  The effluent contains less than Img/l of iron, an overall treatment efficiency of 95%.