R&D Project 7 – Lining Materials for Sea Water Pumped Storage Dams

One of the most important sources of water is groundwater, and it is not impervious to pollution. The main source of pollution is the leakage of polluted streams such as open drains for channels. The purpose of this study is to minimise the contaminant to protect ground water of channel and dams. To investigate the contaminant flow and the efficiency of different materials of lining, MODFLOW is used. This study tells us about the different lining materials such as geomembranes, clay, concrete and bentonite. 

A method which includes the formation of a membrane with the lamination of butyl sheet and different layers of synthetic fibers. It helps in preventing the water to escape through different holes or cracks in a reservoir or waterway. The lining of reservoir or waterway with the help of membrane and sheets is done to seal the joints in between sheets and sprayed of high density concrete on the fiber layer. The word waterway is referred to canals, rivers, aqua ducts and underground channels of irrigation. One of the main existing method of lining includes the excavation of ponds, channel and dams out of the ground level and then provide lining the base and walls of ponds, channel with concrete. (Christakis, 2013) 

Figure 3 – Dam and Pond liners 

Geomembranes

Geomembrane is generally used in this paper to replace the other terms which are used for lining systems. It is basically consists of different layers of synthetic sheet to make an impermeable barrier. These are generally produced in the form of rolls of different sizes such as 1000 feet long and range of width is 6 feet to 33 feet. The thickness of geomembranes ranging between 30-100 mil. There are some common geomembranes which are used for the lining purposes. 

Polyvinyl Chloride 

PVC is the most common geomembrane which is used to fill the lands such as rock fill and earth fill. Generally, it is a thermoplastic liner material. These membranes have successful results on the performances of different dams throughout the world. In 1960, PVC geomembrane is applied onto the dam for lining in the first time in history. It is a superior lining product among all the geomembranes due to its service life of approximately 30 years without any replacement. The main advantage of polyvinyl chloride is its successful performance around the worldwide. It also allows the visual inspection for repairing in future if something is exposed. They have better elongation, tensile, resistant and puncture properties. To increase the frictional resistance, special type of PVC liners are used. (Young, 1978) 

Elestomeric 

The material which is formed by the group of different geomembranes thermostat rubbers, is known as elestomeric. According to previous research, ethylene propylene diene monomer is one of the most useful elestomeric geomembrane for various evaluations and applications of dams. Butyl rubber would also be used in this context. Back in 2006, there are only eleven dams around the world which uses geomembrane of elestomeric system. The elestomeric geomembrane was used in 1982 for the first time in history. The main advantage of elestomeric is the characteristics of their strength, control of seepage and also having good appearance. These materials have high puncture resistance and better elasticity. The life span of elestomeric materials are less as compared to PVC and bituminious. (Murabayashi, 2001) 

Figure 5 – Elastomeric Geomembrane 

Compacted Clay Liner 

Compacted clay liner are generally composed of very small clay sized particles which are obtained from the onsite. CCLs have been primarily used to reduce the seepage for a long time by using the soil. The thickness of compacted clay liner is according to their hydraulic conductivity and can be determined by laboratory tests extensively. The thickness of CCLs are up to three feet and yield permeability is about 10-7 cm/sec which depends upon the compaction effect and the percentage of clay. Compacted clay liners are extensively used as a liners mostly in dams. Is can easily be constructed with simple earth moving equipment. (Christakis, 2013) 

Geosynthetic Clay Liner

Geosynthetic clay liner are basically composed of granulated or powdered bentonite clay which is bonded between non-woven textiles. These are the most popular liner used in the lining of dams because their 4 to 6 mm thickness of geosynthetic clay liner has equal or greater yield permeability than the three feet thick compacted clay liners. In 2001, GCLs are used for the first time. They are generally easy to install and having high characteristics of seepage control other than all of the liners. The main advantage of using the GCLs is that it has the ability of self-healing because of hydration of the bentonite. In United States, installation of geosynthetic clay liner is very limited. (Pepper, 2000) 

Conclusion

Generally, this invention helps a lot in the lining of reservoir or waterway to laminate. In this method, lining of reservoir or waterway also includes the laminating layer of fibrous material with the layer of liquid and flexible material. It should be applied to the outer surface of rigidly or semi rigidly fibrous material. After the lining, there are less chances in the leakage of water in cracks of concrete lining. Due to fluctuation in temperature, cracking and movement of the concrete could be occur. To avoid this, precast concrete slabs are used which are joined by casting the concrete with the help of shuttering. 

Specific Milestone Objectives

The project comprises 3 milestones, where: 

Milestone 1 is divided into 3 milestones: 

Milestone 1A – Identify specific materials requirements across pumped storage project solution 

Milestone 1B – Classify potential surface materials used globally for each application 

Milestone 1C – Categorise by cost, effectiveness, anti-erosion, prevention of adhesion of marine organisms and other technical considerations 

Milestone 2 is divided into 3 milestones: 

Milestone 2A – Systematic verification tests to investigate corrosion characteristics of metallic materials 

Milestone 2B – Systematic verification tests to investigate the effects of corrosion preventative paints and cathodic protection 

Milestone 2C – Systematic verification tests under simulated running conditions of adhesion characteristics of marine organisms endemic to the Cape West coast 

Milestone 3 is divided into 4 milestones: 

Milestone 3A – Investigate the effect of sea water and sodium chloride on the compressibility behaviour of clay soil 

Milestone 3B – Investigate effectiveness of bags partially filled with stimuli-responsive highly absorbent polymers for lining dams

Milestone 3C – Investigate the effectiveness of a drainage layer constructed of gravel materials of 20mm or less as an effective lining structure based on commonly available local materials 

Milestone 3D – Final report providing comparison matrix of materials 

References

1) Katsaprakakis, D.A., Christakis, D.G., Stefanakis, I., Spanos, P. and Stefanakis, N., 2013. Technical details regarding the design, the construction and the operation of seawater pumped storage systems. Energy, 55, pp.619-630. 

2) Young, D.A., 1978. Method of lining a waterway or reservoir. U.S. Patent 4,065,924. 

3) Murabayashi, E.T. and Fok, Y.S., 1983. WRRCTR No. 152 Stream-Water Storage in the Ocean by Using an Impermeable Membrane. 

4) Pepper, R.G. and Burke, K.L., 1990. Clay lining of leaking earth dams. Agricultural water management, 17(4), pp.379-390.