Current operations at Durnford Quarry
With three million tonnes of stone remaining, and with demand falling, the decision was made in 2007 to decommission the large aggregate processing plant and replace it with modern mobile crushing and screening equipment. Planning permission was granted to allow more time for the remaining stone to be removed and also for the amount of aggregate recycling to increase.
The photograph above left shows the old fixed processing plant.
The photograph above right shows the new mobile crushing and screening equipment sited in the base of the quarry previously occupied by the large primary crusher and transfer house buildings.
An advantage of mobile crushers and screens is that they're much smaller and hence visually less intrusive. Operationally, they are more energy efficient than the old static plant that used to be at the quarry and they are also cheaper to maintain, repair and operate. In addition, it is much easier to change the processing arrangements so that the size of the aggregates produced is consistent with the market demand. This means that the stock piles of aggregates for which there is less market demand is much smaller.
The photograph above left shows the old secondary processing plant, being the large structures toward sthe top left of the image.
The more recent photograph above right shows the current layout of the secondary Recycling processing site, with the aggregates recycling operations being undertaken in the area, previously occupied, by the large secondary plant house.
In 2008, the production of stone at the quarry (known as primary aggregate) was 250,000 tonnes, together with 70,000 tonnes of recycled aggregates. All of the products from Durndford quarry, some of which are listed below, are manufactured in accordance with British Standards. All our BSi certification can be seen on Tarmac's website.
Dry stone
A variety of sized products are produced, depending upon market demand.
Recycled aggregates
These are produced from the inert waste materials which mainly come from construction and demolition sites, and include material from utility trenches, concrete, blocks, brick, tiles etc. In addition, road planings, produced when old road surfaces are replaced, are also processed on site to produce a secondary aggregate. Some of our recycled products are then blended with the dry stone to form special products.
Asphalt
The asphalt plant at Durnford can produce over 200 different mixes, however around 20 mixes are regularly used, depending on the customers’ requirements. Much of the asphalt produced at the site uses limestone from the quarry, with imported sand, bitumen and blending materials. In 2008 the quarry produced around 50,000 tonnes of asphalt, the majority of which was used in maintaining the road network in Bristol and North Somerset.
Concrete
The concrete plant at the site is operated by a third party and uses limestone produced at the quarry with imported sand and cement. In previous years in excess of 50,000 tonnes of concrete has been produced but the current economic climate saw this fall to 35,000 tonnes in 2008.
