Concrete spillway – By building spillways along the slopes, they allow part of the water to run down to the bottom of the lake. In time, this reduces the water from infiltrating below the surface of the ground.
Vegetation Method – Vegetation is a plant ground cover method by which new plants are constructed on an empty patch of land. This method strengths the over all structure of the slope as the root of the plants hold stably on the soil. Plants also help absorb part of the water from beneath the ground surface through the process of transpiration, which also increase the stability of the slope.3
Destination 2 - Tarmac Quarry (Skipton)
Rock Production and Structure
Tarmac Quarry is a limestone production quarry. Limestone is commonly used in many constructed buildings. It is a fairly soft material and easy to cut into blocks. However, it is relatively expensive and heavy to manoeuvre, therefore it is impractical to use on tall buildings. Let us look at some of the properties of limestone.
Limestone
Limestone is classified as a sedimentary rock. It is made up of calcium carbonate, CaCO3. Due to its very fine-grained, variety of colours and smooth texture, therefore it is largely used as a decorative building material, such as tiles and walls.
Limestone is an alkaline material. Therefore, it is fairly reactive to an acid solution, such as acid rain, due to oxidation reaction. As a result of this, some of the rock facings were left with a trail of white marks.
Stability of slopes
During our field trip, we were taken to a disused excavation area to study the folds formation between the rocks.
The fold formations between the rocks are formed under different environments due to stress, pressure and temperature. The angle of the fold can be defined by the terms strike and dip. Strike is when the fold is facing inward towards the rock facing and dip is the fold angle which is ninety degrees from the strike angle. The excavation area was disused due to the unstable layers rocks beneath the mountain. I will explain this further using a sketch on the next page.
Destination 3 - Coldstone Quarry
Rock/ mineral structure and types
Coldstone Quarry consists of two main materials. These are:
- Galena
- Fluorspar
- Limestone
Galena - Galena is a lead sulphide mineral. It is an important lead ore mineral and is usually seen in many crystal cubes. It has a Moh’s hardness of 2.5, therefore it is a very soft material. Most leads are used for making batteries and pipes. It also contains significant amounts of silver sulphide mineral, which creates a silver metallic surface to the material.
Fluorspar - Fluorspar (also known as fluorite) is a mineral composed of calcium fluoride, like Galena it comes in many crystal cubes. It has a Moh’s hardness of 4 and a vitreous lustre. It is widely used in the steel industry for removing impurities from the molten metal once it’s been added into the furnace.
Limestone - Limestone is classified as a sedimentary rock. It is made up of calcium carbonate, CaCO3. Due to its very fine-grained, variety of colours and smooth texture, therefore it is largely used as a decorative building material, such as tiles and walls.
Methods of excavation
One of the main excavation methods is called blasting. This method requires drilling small holes deep under the ground surface by using a drilling machine. The position of each hole is precisely measured at twenty-five meters away from the next and two meters away from the nearest rock facing. These measurements are fairly important because the after effect of blasting may cause the nearest rock face to collapse under the intense vibration.
Explosives are then implanted into the holes and detonated individually with two to three minutes waiting period after the last explosion. This creates less noise pollution to the residents who lives around the area. After the rocks had been excavated from the ground, it is then transferred by a carrier to a plan factory and under goes a series of crushing process and sorts out different sizes of rocks.
Crushing process
The crushing process is as followed:
- Rocks enter the processing machinery.
- A set of rolls of different sizes are applied for sorting out different sizes of rocks.
- The larger pieces of rock are then sent to a primary crushing chamber and the rocks would be crushed by a pair of jaw crushers.
- These rocks are then taken by the conveyer belt and go through another process of sorting. Parts of these rocks would be now taken and piled away according to their sizes.
- The rocks that are still too big to by past the sorting machinery would be taken to a secondary crushing chamber for further process
- Final product
Usage of produced materials
The produced materials from the quarry would be sold to different clients. They would use these materials in many constructions (such as road resurfacing and leisure centre flooring) according to the sizes of the rock.
Destination 4 - Thurscross Reservoir
Geology of the area
Thurscross Reservoir was built on a high and a remote location. Constructing a reservoir and a concrete dam at such a remote area allowed fewer disturbances to the residents.
As the reservoir was built on a very high location, it maximised the water collection and also required no use of energy to transfer the water from the reservoir to the water treatment plans. It relies purely on gravity to transfer the water, conserving energy and money as well as environmental friendly.
Cross-section and Features
The Thurscross dam was supported by seven main beams and it is sealed with a well mended concrete stone wall. The front of the dam wall was tilted at a small inclined angle and the back facing was ninety degrees retaining the water in the reservoir.
The dam has five water exits allowing water to escape when the reservoir is over loaded with water. These exits were constructed at the centre of the dam, allowing the water to escape from a high kinetic energy zone (the top of the dam) to a low kinetic energy zone (the bottom of the dam) and directly into the lake .
During the visit, we found that the water exit towards the centre of the dam was slightly lower in comparison to the side exits. This was said to be the primary exit. As a result of this feature, it guides the water to the main exit. This reduces the chances of unmanageable water flow and also prevents the level of corrosion and damage caused to the structure.
Construction and Materials
The Thurscross dam was made of three major materials
- Granite
- Concrete
- Limestone
All of these materials were used on different parts of the dam. I shall discuss each material individually down below.
Granite – Granite rocks were applied on the back facing of the dam. Due to its rough surface and hard wearing mechanical properties, it reduces the speed and maintains control of the water flow.
Concrete – The concrete blocks were applied to the over all structure of the dam. They make up the heavy weigh to withstand the water pressure from the reservoir and stop the dam from collapsing.
Limestone – Limestone was used on the front facing of the dam. Due to its smooth surface and fine-grained, this increases the speed up of the water flow due to a reduced the amount of friction.
