High temperatures experienced in the Gulf Cooperation Council (GCC) countries during summer makes consumption of water straight from the taps impossible. Many homes use multiple water coolers and refrigerators 24 hours a day to cool the water. The amount of power consumed this way leads to a large additional electric load on the grid. Because of the PLC Controlled Water Cooling System design, it is possible to cool all the water used in a home centrally in the main storage tank thereby eliminating multiple cooling systems. Through a control panel that can be installed anywhere in the home, users set the desired water temperature. The panel controls a compressor, which cools water to the desired temperature. The compressor goes offline once the temperature falls to the desired level.
Introduction
TEMPERATURES in Gulf Countries rise up to 500C during summer. This makes consumption of water from tanks and reservoirs by residents extremely difficult if not impossible at all. The need for palatable water necessitates use of water coolers. Typically, a single home has several of water cooling units in addition to refrigerators used for cooling and storing cold water. With the application of a PLC Controlled Water Cooling design as proposed in this paper, it would be possible to eliminate the use of multiple water coolers and refrigerators used purposely for the cooling and storage of drinking water.
Previous Inventions
In 1974, Robert C. Webber designed a system for simultaneously cooling a building and warming water in a swimming pool. Webbers’ system employed a refrigerant running through conduits that connected the compressors and condensers. He used thermostatically controlled valves to regulate the action of the compressors and the condensers. When the building temperatures dropped below preset levels, the thermostatic valves made it possible for the refrigerant to bypass the buildings evaporator and to conduct the refrigerant through an auxiliary evaporator.
Industries employ several other systems for water chilling. One of methods used is the waterwall water cooling system designed by Kohring, F. C. He demonstrated that this method had an enhanced cooling efficiency among other advantages when compared to conventional cooling systems. Interstand cooling, runout table cooling, work roll cooling and descaling are hot strip mill applications that use this method. In addition, the system was useful in plate mills and bar mills.
Scope
This project’s design compares closely to Webbers design. The scope of the project is to design and build a system for cooling and heating water in tanks/reservoirs for domestic customers. In this design, an electronic control panel (SD-94M) has replaced the thermostatically controlled valves in Webbers design. The user uses the panel for input of the desired water temperature. The compressor is operated by a low cost SIEMENS PLC (LOGO module) which turns the compressor ‘ON’ or ‘OFF’ depending on prevailing and desired water temperature as set by the user. This paper reports on the design procedure employed and the results that were been obtained during the first semester. A brief outline of upcoming work in the next semester is included.
System Design and Implementation
Top Level design
A 150-litre water tank with a temperature sensor (PT100) with an evaporator mounted inside provided water storage. The sensor provided an analogue voltage signal proportional to the system’s water temperature. An Electronic Control panel (SD 94M) as user interface, was used to provide the set point temperature. The control panel provided the signal required by the PLC, which had a 45-second delay, to operate the compressor. If the water temperature fell lower than the set point temperature, the compressor remained off but if it rose higher, then the compressor turned ON until the set point temperature was reached.
Figure 1. Top Level System Diagram.
The evaporator was connected to the compressor through an expansion valve, which allowed the water to heat up each time the water cooled by more than 5°C below the set point temperature as shown in Figure 1.
Cooling System
The cooling system resembled that of air conditioning systems, which employ a condensable refrigerant that interconvert’s between liquid and gaseous state depending on the attendant temperatures. This change of state makes it possible for the refrigerant to transport heat from one section to another and releases it usually through a condenser where it liquefies. The key components of a cooling system are compressor, condenser, expansion valve, and evaporator. In this design, the compressor and condenser were located outside the reservoir while the evaporator was located inside. The evaporator connects the two portions as shown in Fig 2.
Figure 2. Cooling system.
System Operation
The input temperature range for the control panel is 0°C to 50°C. This input voltage is converted into a voltage level of (200mV per °C), which yields a set point voltage level of between 0V and 10V.
The sensors’ working temperature range is between -50°C to +200°C [3] in units of 1°C. Its output voltage ranges 0-10V in units of 40mV. The sensor is limited by poor resolution of the control panel’s analogue to digital converter and line noise, reducing the minimum detectable voltage to 50mV (40mV*1.25)
Since we are only concerned about temperatures between 0°C and 50°C as this is the limit of the set-point temperature we can set from the control panel, a voltage level converter in the control panel changes the sensor’s output voltage (50mV per °C) to the same level as the set-point voltage level (200mV °C). This is done by first multiplying the sensor’s voltage level by 4 to get 200mV increment per °C and then removing the -50°C to 0°C offset that is (40mV*50 = 2.5V). By doing this, the sensor’s output voltage now changes from 0V-10V with an increment of 200mV per °C that is same as the set-point voltage increment. The sensor’s voltage level (after conversion) was converted to °C by dividing by 200mV and this temperature in °C was displayed on the control panel. In this way, the user can monitor the set point and the actual water temperature on the same display.
Figure 3. System Operation.
The control panel uses a relay system to operate the compressor, turning it ON whenever the set point voltage level is lower than the sensors output and turns it off if the voltages are equal or lower than the set point voltage. The Siemens LOGO PLC provides the interlink between the relay and the compressor and, turning the compressor on each time the relay is ON and turns it OFF each time the relay is OFF.
Software Description
The software used to develop the ladder diagram was LOGO! Soft Comfort, Version 4.0.51.
A 240V supply comes through the main power source labelled I1, indicated by the coming ON of pilot lamp Q1. The desired water temperature is then set through Input sensor I4 (Sensor PT100) which connects to the controller which regulates its functioning. The controller’s screen displays water temperature when the system turns ON. If the reading exceeds set temperature (e.g. 20c°~30c°) , Input I4 is triggered, sending a signal to delay timer T002, set at 45 seconds, as a compressor safety measure. After the delay time lapses the compressor comes on line to lower the water temperature. Upon attaining the set temperature value, Input I4 opens, stopping the compressor.
In addition to the green coloured pilot light (Q1) which indicates whether the system is on, there are also two other pilot light Q3 and Q4 which indicate whether the system is heating or cooling , respectively.
Figure 4. PLC ladder diagram.
The project schedule used to conduct this project is indicated below.
Testing Results & Conclusion
The prototype was assembled on a wooden frame, which carried the 150-litre tank used, compressor, control panel, and PLC. The evaporator and the sensor were mounted inside the reservoir tank included the. All tests were undertaken at RMIT labs. The key test for the cooling system involved adjusting the set point temperature between 5°C and 20°C, which successfully caused the compressor to turn ON whenever the actual temperature was higher than the set point temperature, and OFF otherwise. These measurements were however not tested against any other temperature sensor.
Future Work
The design of the PLC Controlled water Cooling System features a closed loop structure. It does not operate in real time however because the PLC timer has a 45 second safety delay to curb sudden switching. There are plans to fit a PID controller on the same assembly in the coming semester. This will necessitate a new pole assignment design to accommodate the controller’s parameter requirements. With the PID controller online, it will be possible to activate the heating functionality with a set point of 25°C. The systems’ sensor will require calibration against different temperature sensors available in the market to enable in-depth system performance analysis. The addition of a hysteresis level to restrict the compressor to turning ON only under minor temperature changes will improve performance. Finally, the study of power consumption of the system earmarked for the next stage. This will be one of the areas for exploration in the coming semester, comparing the systems power consumption with and without a PID controller. This analysis will also include a comparison of power consumption between this system and other systems in the market.
References
Webber R.C., Building Cooling and Pool heating system, (1975).
Water conservation and drought issues are inevitable in some resorts. The primary reason refers to the fact that demand for fresh water increases with the growth of population and urbanization while supply decreases. The tourism industry is closely connected with water issues due to several reasons. First, most resorts are situated near large rivers and sources of fresh water. Their operation is often dependent on the natural resources of water. Second, the inappropriate water management leads to pollution. Finally, tourism depends on the availability of sources. Several cases exemplify instances when resorts’ activity has been damaged by severe droughts. In the following paper, the water conservation and drought issues in resorts will be investigated and evaluated. Theoretical background on ecotourism and water conservation and real life examples have been used for the paper.
Introduction
Weather conditions and climate changes affect tourism industry drastically. The availability of water is crucial for particular types of tourism. The primary reason for this is global. The scarcity of water resources is terrifying. Also, the ability to save natural resources increases the potential competitiveness in the sphere. Although the implementation of the proper water management is a time-consuming process, it is of primary significance for the future development of tourism as far as most resorts face problems with water consumption.
Background and History
The idea of the conservation of natural resources and water, in particular, became popular in the previous century. It was the time when the notion of ecotourism appeared. Before providing specific examples, it is necessary to examine reasons that predetermined the development of ecotourism.
According to Ballantyne and Packer (2013), natural resources have always served as a major attraction for people. The understanding of the need for nature protection commenced in the 1960s. In those years, people became aware of such issues as environmental protection, pollution, extinction of animals, and scarcity of resources. The mass tourism became popular in the same period. As far as tourism was always based on natural resources, the questions about nature protection became urgent. Consequently, the International Union of Official Travel Organizations has introduced the environmental tourism policy. In 1972, the Ecodevelopment Strategy was initiated at the United Nations Conference on the Human Environment.
The other reason for changes in tourism is connected with expectations about water availability. The demand for water increases annually while supply decreases. By 2015, the demand for water is expected to rise by 55% (Gossling, Hall, & Scott, 2015). Gossling et al. (2015) also write, “as a result of increased water demand over the coming decades, UN Water (2014) estimate that as much as 40% of the global population may live in areas of severe water stress by 2050, as aquifers are overexploited and groundwater supplies decline” (p. 15).
Finally, numerous examples prove the necessity to conserve water and find solutions for dealing with droughts. For instance, the State of Colorado experienced a severe season of spring and summer droughts. Conditions in wildlife became dangerous, and the number of visitors decreased by 40%. Also, drought influenced the fishing industry. Fishing was prohibited as far as fish species were in poor condition due to the low level of water (Scott, Hall, & Gossling, 2012).
Literature Review
The investigation of environmental issues and their relation to tourism should start from the identification of tourism-environment relations. According to Holden (2012), it is rather a challenge to evaluate relationships between tourism and environment. Tourism is a system that includes a variety of aspects such as stakeholders, the private sector, government, non-governmental organizations, and tourists. In general, tourism-nature relationships define the human attitude towards the environment.
As human activity, tourism may influence environment differently. Holden (2012) examines the positive and negative impact of tourism on nature. Adverse effects of tourism may be viewed at two levels: global and local. On the global scale, scholars argue that tourism facilities, such as airplanes, negatively influence environment. The primary concern refers to the emission to carbon dioxide. Although air companies claim that the level of emission from airplanes is much lower in comparison to other activities, the threat exists. One may assume that there is no connection between air pollution and water conservation in resorts. On the contrary, there is a direct connection.
The emission of carbon dioxide enhances the greenhouse effect. It leads to the changes in climate, and that, in its turn, modifies water demand and supply in the world. The other global issue concerns water pollution. This problem is typical of many resorts in the world. Holden (2012) writes that “in the most visited tourist area of the world, the Mediterranean, only 30 percent of over 700 towns and cities on the coastline treat sewage before discharging it into the sea” (p. 20).
Tourism may also affect the natural environment on the local level. In most cases, it deals with the destruction of local habitats for the development of tourism business. The treatment of coral reefs may serve as the first example. The diversity of species on coral reefs can be compared to that of the rain forests. The building of new tourism facilities often destroys reefs. For example, the inadequate system of sewage and rubbish discharging as well as the building of new tourism constructions undermine the security of almost seventy percent of all coral reefs at the coast in Egypt (Holden, 2012). The other local threat refers to the individual treatment of tourists. Most of them do not realize the significance of coral reefs from the environmental perspective. Even if they do, they just neglect it. Consequently, tourists or divers may break reef to get a souvenir or walk on it. Such damage is devastating for coral reefs.
Nevertheless, tourism has positive effects on the environment as well. Holden (2012) expresses the idea that tourism should be regarded as an agent of conservation. In comparison to other types of human activity such as forestry or agriculture (that require the modification of soil and destroying of habitat), tourism aims at the maximum protection of the environment. Its success depends on the preservation of nature. Thus, such terms as ecotourism, nature tourism, responsible or sustainable tourism are becoming more and more popular nowadays.
According to Buckley (2013), the concept of ecotourism remains rather controversial until nowadays. There is no exact definition of ecotourism although there are several principles that can be met in most definitions. The first opinion is that ecotourism is a sub-type of tourism. The second component of ecotourism refers to the notion of the environmental management. This kind of management is often used together with the term “sustainability”.
Another view concerning ecotourism relates to the fact that it is nature-based. Thus, ecotourism may be realized only in natural settings. The next constituent of the definition is about education. Ecotourism should educate travelers to use water appropriately, for instance. The following aspect of ecotourism is conservation of resources. It is essential for the creation of harmonic relations with nature. Some scholars also consider that ecotourism brings social benefits, especially to residents. As a result, people live in safe places and do not worry about the deterioration of their health conditions (Buckley, 2013). Still, the concept of ecotourism is extremely controversial because it is in the process of development. Nevertheless, water conservation should be regarded as a part of ecotourism as far as it aims at improvement of the environment.
The functionality of almost all tourism facilities depends on the sufficient supply of water. According to Cole (2013), there is little research concerning the relations between water availability and tourism. The lack of adequate research results in improper water management in resorts. One should also differentiate two types of relationships between water and tourism: consumptive and non-consumptive. A non-consumptive type refers to the usage of water for recreational activities. Consumptive relationships occur when there is a need to manage wastes and provide comfortable accommodation.
Scientific investigations of the water consumption and tourism were based either in the Mediterranean region or in Australia — places where tourism comprised a significant part of the infrastructure. Cole (2013) considers that there are several reasons for water inequity in developing countries. The growth of population, rapid deforestation, urbanization create a tension in the tourist sector as well. Besides, water infrastructure has many deficiencies. Water is used to make tourism attractive and comfortable. Consequently, the adequate water management is necessary for the development of business in the pressuring environment.
The primary reason for water conservation refers to the global issue of water scarcity. A demand for water is estimated to exceed supply by forty percent by 2030 (Tuppen, 2013). It means that half of world’s population will be living in places where water scarcity will be an urgent problem. Ninety-seven percent of all water are in oceans. Fresh water comprises only three percent of total water supply. Only one percent of fresh water is in rivers, lakes, atmosphere and underground. The other two percent are in glaciers.
Growing population and urbanization require a lot of water. Climate changes are becoming more and more unpredictable nowadays. According to Gossling et al. (2012), water use tripled in the last fifty years. The term “water stress” is used to describe a condition when people suffer from the water scarcity. In 1995, almost fifty million people faced the problem of water availability. Scientists consider that more than three billion people will live under water stress by 2100 in case the climate change reaches four degrees (Gossling et al., 2012).
These findings prove the need to save water resources and improve water management. As it has been already mentioned, the increasing need for water usage is connected with the growth of population and demands. Agriculture is regarded as the most water consuming activity. Gossling et al. (2012) find that tourism is another significant factor that requires a substantial consumption of water. For instance, tourists need water when using the toilet, taking a shower, going into swimming pools. Fresh water is also necessary for maintaining tourism attractions including landscapes, gardens, and other facilities. Owners of resorts have commercial reasons for water conservation as well. Water comprises up to ten percent of unity bills in most resorts (Tuppen, 2013).
Mei-feng, Jian-chao, and Sheng-he (2014) examined the connection between the tourism industry and water environment. According to their study, three reasons predetermine the significant influence of tourism on the water environment. First, many tourism bases are situated at large water reserves. Second, tourism has adverse effects on the water usage in particular areas. It is necessary to mention that residents of some local areas face problems with water usage due to the extensive development of tourism zones (Mei-feng et al., 2014). Finally, owners of resorts may establish an advanced system of water management, and, in such a way, improve the situation with water pollution in particular areas.
The development of water management plans is of great significance for resorts that are situated in water-stressed regions in the world. Pacific islands are popular tourist attractions. This popularity usually results in the lack of fresh water for the local population. In tropics, the problem of water management in related to season changes in climate. For instance, long-lasting droughts are usually accompanied by increased usage of water reserves. Such treatment is harmful to the environment. Bromberek (2009) emphasizes that all resorts produce water on their own though do not treat it adequately. The author writes about gray and black water.
Gray water comes from bathrooms, sinks, washing machines, and showers while dark water — toilets and dishwashers. In most resorts, these wastes are just discharged into the natural environment without treatment. Discharging of water waste may lead to the pollution of local habitats. Also, resorts may save a lot of water with the help of systems for water management (Bromberek, 2009).
Kuoni Group developed “Kuoni Water Management Manual for Hotels” that can serve as a useful guide for every resort. According to Kuoni Group (n.d.), water management is a prolonged process that comprises of several steps. Considering the usage of innovative technologies for water management is important. Thus, gray water can be used as a renewable source of water. Also, the installation of water-saving technologies such as low-flow showerheads, tap aerators, flow regulators, and flushing volumes can reduce the water consumption substantially. Finally, it is of particular significance to train staff and develop consumers’ understanding of the need. For instance, tourists may be asked to keep taps closed while brushing teeth or use the same pool towel during the day (Kuoni Group, n.d.).
Best Practices in Industry and Solutions
Numerous researchers have discussed the significance of water conservation and drought issues. Nowadays, the status of the discussed subject is of primary importance for water-stressed regions. The following real life examples demonstrate best practices to overcome water consumption issues:
Starwood Hotels & Resorts Worldwide, Inc. This company is one of the most reputable providers of leisure facilities in more than one hundred countries over the world. The consumption of water by Starwood was immense as the company began expanding. As a result, the company realized the need to reduce water usage almost ten years ago. Starwood has an advanced system of water reduction and spares no means on further development of water conservation technologies. The following infographics represents Starwood’s initiative (Our Water Story: Thinking Beyond Conservation, 2015).
Disneyland Resort in California. California’s climate is known for prolonged periods of drought. During droughts, the whole area faces a challenge of proper water management. Disneyland Resort in Anaheim needs plenty of water for the creation of Disneyland’s wonders. In 2008, the company installed Groundwater Replenishment System for water recycling. This system purifies already used water. Hotels in Resort are equipped with low-flow showerheads and toilets, urinals, and aerators. Various innovative systems control irrigation. For instance, drip irrigation and cut-off valves assist in timely identification of leaks (Water Conservation, n.d.). Authorities of Disneyland Resort also prefer planting drought-tolerant plants that do not need a lot of water for survival. In such a way, Disneyland Resort attracts even more visitors by stating that the park is environmentally friendly.
Boutiquehotel Stadthalle in Vienna. Hotel’s initiatives are considered to be one of the best practices in Europe. Hotel owners became interested in ecotourism since 2000. They acknowledged the need to save energy, water, and enhance sustainability in general. Boutiquehotel Stadthalle received many awards including EU Ecolabel and Austrian Ecolabel. In 2015, the hotel was awarded the Green Hotelier Award in Europe. The primary accomplishment of the hotel is the building of the passive house. The passive house operates on its own energy produced from renewable sources such as solar power and water. Also, visitors decide about the frequency of changing their linens and towels in the hotel. Water from the local well is used for the activation of the passive house (O’Neil, 2015).
Lady Elliot Island in Australia. This resort is located on the southern side of the Great Barrier Reef. The location of resort predetermines the need to implement the effective water management strategies. Thus, the island is isolated from rivers and runoffs. Water around the island is exceptionally clean. A proper wastewater management is necessary in such location. The direct disposal of sewage would result in water pollution. The supply of fresh water is realized via the Dunlop IBC reverse osmosis desalination system. The system converts sea water into fresh water. It should be mentioned, that the resort has a solar power station for this system (Water Conservation, n.d.). Lady Elliot Island promotes environmental awareness of their guests and asks them to control the change of towels and everyday water use.
Pebble Beach Golf Resort in Northern California. Drought in California hindered the activities of numerous resorts. The principal problem of the resort concerned the water discharge system. Thus, a resort discharged all water waste into Camel Bay. Recently, resort invested 67$ million into the project for the reduction of discharge. The proper irrigation system predetermines the popularity of the golf resort. “An irrigation system is based on evapotranspiration rates, soil probing, visual inspection and the weather” (From Disneyland to golf resorts, California tourism adapts to drought, 2015, para. 12).
Resources and Future Implications
The following web sources can be useful for the further research on the subject:
kuoni.com/docs/kuoni_wmp_manual_0_0_4.pdf — it is the link to the Kuoni Water Management Manuals for Hotels. This manual provides a comprehensive description of all necessary steps towards the efficient water management. A visitor may read about every stage of the plan starting from planning and ending with the creation of customer awareness. One can see various tables and graphs that provide useful information.
Greenhotelier.org is the principal online source when it comes to the developing of sustainability in tourist resorts. A visitor may find many useful articles concerning water issues. Besides, there is a rubric describing best ecotourism practices in the world.
Thetravelfoundation.org.uk is the official website of the charity organization that aims at providing best services for people as well as taking care of the environment. One can read about current projects and news relating not only to water conservation and drought issues but tourism industry in general.
Ecotourism.com is one more source that is useful for gathering information concerning a sustainable tourist industry. One can choose the region of interest and find more information about the particular destination.
The topic of water conservation and drought issues is significant as far as it is directly connected to the well-being of the humankind. Tourism is a factor that influences the environment and water reserves drastically. Climate change and inappropriate management may result in little interest among visitors. Ecotourism is a new kind of tourism, and it is the way to future success. People become more environmentally aware. Consequently, they will prefer environmentally friendly resorts. Besides, ecotourism is a good way to save money and protect nature at the same time. Thus, most resorts should consider the idea of implementing water conservation plans for their future development.
Conclusion
The necessity to promote water conservation and address drought issues is proved by real life examples. Global issues such as water scarcity and local pollution of water are exact examples of the negative impact of tourism on the environment. The notion of ecotourism has been introduced to present a new age of ecologically friendly resorts. Nowadays, water management is becoming more and more significant for many resorts. The recycling of water, usage of low-flow showerheads and toilets, and economical irrigation systems are the most popular ways to conserve water and retain functionality during droughts.
References
Ballantyne, R., & Packer, J. (2013). International Handbook on Ecotourism. Cheltenham, United Kingdom: Edward Elgar Publishing. Web.
Bromberek, Z. (2009). Eco-resorts. London, United Kingdom: Routledge. Web.
Buckley, R. (2013). Defining ecotourism: consensus on core, disagreement on detail. In R. Ballantyne & J. Packer (Eds.), International Handbook on Ecotourism (pp. 9-15). Cheltenham, United Kingdom: Edward Elgar Publishing. Web.
Cole, S. (2013). Tourism and water: from stakeholders to rights holders, and what tourism businesses need to do. Journal of Sustainable Tourism, 22(1), 89-106. Web.
Gossling, G., Hall, M., & Scott, D. (2015). Tourism and Water. Bristol, United Kingdom: Channel View Publications. Web.
Gossling G., Peeters, P., Hall, M., Ceron, J., Dubois G., Lehmann, V., & Scott. D. (2012). Tourism and water use: Supply, demand, and security. An international review. Tourism Management, 33(1), 1-15. Web.
Holden, A. (2012). An Introduction to Tourism-Environment Relationships. In J. Hill & T. Gale (Eds.), Ecotourism and Environmental Sustainability (pp. 17-30). Farnham, United Kingdom: Ashgate Publishing, Ltd. Web.
Kuoni Group. (n.d.). Kuoni Water Management Manual for Hotels. Web.
Mei-feng, Z., Jian-chao, X., & Sheng-he, L. (2014). Simulating the saturation threshold of a water environment’s response to tourist activities: A case study in the Liupan mountain eco-tourism area. Journal of Mountain Science, 11(1), 156-166. Web.
O’Neil, S. (2015). Boutiquehotel Stadthalle: a unique passive house hotel. Web.
Forward osmosis and vacuum membrane distillation are common tailing water treatment methods. In forward osmosis, the solvent is passed through a tube of varying concentrations. During the process, solutes move from a region of low concentration to high concentrations. In thermal membrane distillation, a combination of membrane technology and phase change is used. As a result, volatile organic compounds are separated from the aqueous region. The solid organic compounds are redirected to the tailing ponds. Vacuum membrane distillation is applied in water tailing and purification processes (Howe & Hand, 2012).
Despite the benefits of the two water tailing treatment technologies, a number of challenges limit their application. The two techniques are affected by technical, safety, and environmental concerns. These challenges remain the major setbacks to the adoption of the two technologies in water tailing treatment. This report will discuss the technical, environmental, economic, and safety concerns facing water tailing technologies (Xie & Nghiem, 2013).
Environmental challenges
There are many environmental impacts and challenges associated with the treatment of tailings water. For example, the need for a tailings pond affects the environment. Existing tailing ponds cover a large surface area. This is a major environmental hazard to the people living near the treatment plants. Other environmental challenges also arise during the operation of the tailings pond. For example, the bottom that consists of clay and water takes longer to settle.
The prolonged solidification process affects the growth of planktons on the water surface. The extraction stage also contaminates the remaining water portion with oil and natural chemicals. This affects the survival of aquatic organisms, such as fish in the tailing pond. Oil masks the upper surface of the pond and reduces air circulation in the water. Some extraction chemicals are poisonous to fish and the aquatic planktons (Howe & Hand, 2012).
Tailing water increases the contamination of other potable water surfaces around the pond. At the beginning of the process, water is channeled to the tailings pond. Improper construction of the ponds allows deep seepage of the water to other ponds around the area. The natural chemicals in the tailings water contaminate the potable water within the ecosystem. As a result, the potable water becomes unfit for both human and animal consumption. Such water must first be treated and decontaminated before human consumption (Howe & Hand, 2012).
Tailings water from the ponds contains 70% contaminants such as oil, heavy metals, and hydrocarbons. In most facilities, the wastes are released to nearby water bodies. This presents a major environmental challenge to the local inhabitants and the government. With forward osmosis and vacuum distillation, the tailing water must be treated before being released to the environment. Most agencies involved in water tailing have faced environmental sanctions due to a lack of proper treatment of tailing discharge. The environmental concerns have affected the adoption of forwarding osmosis and vacuum distillation in tailing water treatment (Fane & Matsuura, 2011).
The adoptions of the two technologies have also faced resistance to environmental lobby groups. Despite the measures adopted to improve the efficiency of the approaches, lobby groups have openly expressed their opposition. This has affected the successful implementation of the two technologies in the treatment of tailing water. Forward osmosis and vacuum distillation are not sustainable to the environment. The energy consumption of forwarding osmosis and vacuum distillation is unsustainable. With focus shifting to green and renewable energy, operating machines with high energy consumption is uneconomical (Howe & Hand, 2012).
Technical challenges
Tailing water treatment using forward osmosis and vacuum distillation has a number of technical challenges. First, the available designs of the two approaches do not allow the level of water to be increased. As a result, waste materials float on top of the ponds and cannot be removed to maintain the safety of the water. To solve this challenge, the size of the plant must be increased. This allows for the accommodation of a large volume of water and the elimination of challenges associated with waste removal (Xie & Nghiem, 2013).
Manufacturing designs for tailing water treatment equipment have similar sizes. An increase in water volume and overflow is not factored during manufacturing. This affects the economic viability and adoption of devices by different companies. Storage facilities during tailing water treatment are not designed to accommodate the volume for most companies. The design of the treatment equipment for the two methods does not consider the impact of the exhaust. Lack of proper exhaust consideration has caused leakages of the tailing water. This presents a technical and environmental challenge to the use of the two methods (Fane & Matsuura, 2011).
Safety concerns
The design of industrial equipment must consider the safety of the operators and other employees within the facility. The environmental concerns raised affect the operators of the equipment before filtering to the environment. Chemicals released during the treatment of tailing water have carcinogenic properties. Though studies have not been conducted to determine the epidemiology of tumor conditions, there is evidence that the chemical components of the wastes are toxic (Howe & Hand, 2012).
Improper treatment of the waste by the two methods presents significant health challenges to the public. Such toxic chemicals affect fetal development due to their teratogenicity. Exhaust wastes released into the air must be properly cleaned to safeguard the health of the locals. Though treated tailing water has been used for domestic purposes, their safety cannot be ascertained. Adequate measures must be put in place to ensure that tailing water treated through forwarding osmosis and vacuum distillation are examined. Chlorination and sieving can be used to purify the water and kill pathogenic microorganisms (Fane & Matsuura, 2011).
Economic challenges
Despite being efficient, hybrid forward osmosis is costly to acquire and install. Companies that intend to install the hybrid forward osmosis and vacuum distillation incur extra cost as compared to traditional technologies. Product manufacturers have argued that returns on investment using the two technologies is short. However, the cost of installation and operation affects their use in different organizations (Howe & Hand, 2012).
The dykes are also affected by constant blockages and breakdown. This arises from the high suspension nature of the water treated. Constant repair, maintenance and employment of qualified engineers must be done to enhance performance. As a result, the maintenance costs of the treatment plants are very high. Cost is also incurred due to the need to clean the membranes and pipes or channels. This is done to ensure that clean water is channeled to the reservoir (Howe & Hand, 2012).
These two technologies also require highly skilled professionals to operate. This increases the wage gap of organizations that adopt them in the treatment of tailing water. The process is also very expensive to monitor because it requires constant evaluation and monitoring to ensure efficiency. Exhaust wastes released into the air must be properly cleaned to safeguard the health of the locals. Though treated tailing water has been used for domestic purposes, their safety cannot be ascertained (Xie & Nghiem, 2013).
Environmental liabilities also increase the cost of operating the two technologies. For example, the construction of the tailing pond demands for compensation of the displaced. Environmental agencies must also be involved in ensuring that the process meets the set standards. For companies who have limited land, the adoption of forward osmosis and vacuum distillation for tailing water treatment increase the cost of acquiring more capital (Fane & Matsuura, 2011).
The emerging environmental regulations make the two techniques uneconomical. Organizations that increase carbon emission are denied carbon credit and forced to pay for the greenhouse effect caused. This increases the operational cost of such companies. The cost of health hazards and complications arising from the installation of tailing water treatment equipment is high. The introduction of the two technologies must, therefore, be based on the financial strength of the organization and availability of funds (Xie & Nghiem, 2013).
Conclusion
Tailing water treatment has a number of applications in the manufacturing sector. The introduction of forward osmosis and vacuum distillation is believed to have enhanced the process. However, a number of challenges have negatively affected their adoption in different sectors of the economy. This paper has highlighted the economic, technical, and environmental and safety challenges of tailing water treatment using forward osmosis and vacuum distillation methods.
References
Fane, G., & Matsuura, T. (2011). Advanced membrane technology and applications. New York: John Wiley & Sons.
Howe, J., & Hand, W. (2012). Principles of water treatment. New York: John Wiley & Sons.
Xie, M., & Nghiem, D. (2013). A Forward Osmosis-Membrane Distillation Hybrid Process for Direct Sewer Mining: System Performance and Limitations. Environmental Science & Technology, 47(23), 13486-13493. Web.
The group developed an efficient project plan and was able to show a clear understanding of the assignment’s learning outcome. In this assignment, the main areas for group work were the creation of a project plan and the identification, as well as the demonstration of its importance. This entailed highlighting all the essential components that were required for a project plan.
Completing the task needed a thorough plan and fixed parameters for the study. In this case, the group used Pakistan and the project area, which was in 2011 when the actual work took place. Issues of complexity and time limitation emerged after starting out with a drip irrigation system used as part of a Water Management Demonstration Farm, which led to the simplification of the project. It was possible to use the project for the assignment after simplification, where its main parts were two disjointed zones in a drip irrigation system. The project was about the installation of the system with two zones named A and B. Zone A held a mini spray system while zone B had an online dripper system, which facilitated the answering of the project’s research question. The research question was to highlight the working of different systems. Besides, the project entailed the demonstration of benefits associated with either system, with an apparent show of the better one.
Inputs for the projects included information about the location and the nature of the project, as well as the background information about the systems used. In addition, a work breakdown structure, PERT, and Grant charts helped in the preparation. In completing this report, the group made assumptions on the cost of equipment using conventional pricing. Overall, the group was able to highlight its abilities to undertake a real-life project management assignment.
Introduction
The success of project management is only realised when the required tools, techniques, and knowledge combine effectively according to the expectations and demands of large-scale engineering development. It is possible to improve the chance of success of any project, something that can be achieved by being diligent in the use of a consistent methodology and ensuring that there is the commitment to a well-developed plan. This must be considered at the start of the project and while it goes on (Blanchard, 2004). The tools available for project management also help in planning, and they help the manager capture relevant details and the cost associated with different equipment and choices.
A project management plan has a scope, a work breakdown, and charts, with the basic charts being the Gantt and PERT. Each piece of the plan outlines critical parts and brings out the objectives, limitations, and precincts for the project, in addition to the itemisation of the work needed and the time required (Haughey, 2015). Efficient use of the components and following the conceptual considerations of their creation leads to a clearly outlined and organised project.
Demonstrating the usage of these tools and components needed their application in a real project, which was the primary goal of the assignment. The group task led to the choice and implementation of the design, construction, and commissioning of a drip irrigation system that was going to form part of a water management demonstration project as a fictitious project, whose costs would be estimated and some unknown parameters at the time of planning would be assumed. For high credibility, a real project implemented in 2011 was selected as the basis of the assumed one. It was a project implemented in Pakistan by High-Efficiency Irrigation System Consultants (HEISCON), which was considered as an ideal project that would be easily replicated in the fictitious project’s location of remote Western Australia.
Project highlights
Title: Water Administration Demo Park Drip Irrigation System.
Client: Ministry of Food, Agriculture, and Livestock.
Project Cost: $100,000.
Duration: 19 Days.
Company: HEISCON.
Project Scope
Project objectives
The project sought to design, install, and commission a drip irrigation system with the intention of irrigating 12 acres of land divided into two zones of 6 acres each. A borehole would be used as the water source to run the system, which would be developed on the site to sustain water supply and reduce operating costs. Overall, the project cost has an estimated value of $100,000 and aims to reach completion in 17 days.
Project scope description
This project, upon completion, will water land in a conservative way, thereby ensuring that overall consumption of water is minimal and other resources are also used sparingly for maximum benefit. Based on these intentions, the project uses bore water and a drip irrigation delivery system. Besides, food planted in the irrigated area will receive water throughout as the system can run 24/7.
Project requirements
The first requirement is surveying of the land to ensure it is suitable for use in the project and to come up with a preliminary report on what modifications are needed to make it appropriate. After surveying, the design process will begin, and it will encompass two stages of the project, which will add up to two separate areas for meeting the project’s objectives. The two parts of design differ because they are meant for different irrigation systems. Besides, there will be an installation of a filtration system that will be ahead unit for overall water supply to the cultivation field. The completion of the filtration system will mark a significant part of project completion. It will be on the basis of the system using a design that cannot let pipe blockages to occur. Therefore, there will be no design to facilitate draining of blocked pipes because the expectation is to have a blockage-proof system. Other important details are that zone A and zone B will be using similar plot layouts such that it will be possible to provide a measured opinion on the efficiency of resources in both field zones. However, since the two zones use differentiated irrigation systems, their designs will also have variations in pipe diameters and drip fittings to accommodate different requirements of water flow and to bring out efficient gains in water flow before the handover. The objective of the design process and modification of pipe diameters during implementation and design phases is to make sure that the best overall design is implemented and handed over to the client, thereby avoiding recalls and other unwanted interruptions in the system.
Project boundaries
Limitations of the project are presented by its location, which is a remote area. The expectation is that handling and transporting materials will be difficult, given that there is missing access for a container truck or a tipper truck that could unload materials to the site. The other strenuous tasks will be excavation trenching and backfilling because of the nature of the job, but the construction team has the required knowledge and well equipped. The team will be able to pull through with the task as required. Civil works, concrete works, brickworks, and construction work that relate to water tank placement in the project will happen through sourcing third party professionals who are equipped in the respective areas of development. They will work under the supervision of the project management team. Underground pipework will be preferred in case there is a need for a road crossing, although it poses difficulties in its construction due to the need to perform drilling, excavation, and refilling on a tunnel without disturbing road surfaces. The team will handle the job successfully.
Project deliverables
The project comes with four main parameters to fulfil, which are design, water filtration and pump system, zone A, and zone B. For each deliverable, the client will accept the design and cost estimates before installation starts, in addition to the approval of the overall design for the project. The project intends to have a hydro cyclone filter technology used for the water filtration system. It will also use a disk cleaning filter, water meter, and a non-return valve to complete the system. For zone A and zone B, the project will have four control valves and four sub-mains. Moreover, there will be 200 laterals that cover the designated 6 acres of land for each zone.
Project constraints
The project expects constraints to affect the delivery time and the cost of implementation. The constraints will also jeopardise the reliability of the initial design, thereby necessitating modification. One of the limitations is the time taken by the client to approve the project and particular states of implementation. Delays will affect the entire project. Another constraint is the restriction of electricity use from 9 am to 11 am and from 2 pm to 4 pm, which will compel all electrical works to be scheduled at these times. This will negatively affect the speed of other related tasks and may also cause delays in the overall project time. Sites works are limited to commence at 7 am and end at 6 pm, meaning that there will be unnecessary stops of batched work that exceeds the specified time.
Initially identified risks
The project team identifies minor risks that can affect implementation and delivery. Despite their classification as minor, they are still notable. The main ones include excavation and trip hazards. Excavation can affect underground power cables that are not labelled or piping that is unknown at the time of design. The implementing team will work closely with the local authorities to ensure that all service plans are availed before any excavation works commence. At the same time, there will be cautionary calls for workers to be careful at the construction site and the management will insist on the use of safety procedures and clothing when working to avoid trip accidents.
Scheduled milestones
The project relies on fundamental aspects of its implantation, which signify progress and help to make implementation or design improvements to achieve maximum efficacy. The following are the principal milestones:
Designing 31 May 2011.
Installation of water a filtration system and a head unit 13 May 2011.
Installation of zone A and commissioning 15 May 2011.
Installation of zone B and commissioning 18 May 2011.
Training of local operators 18 May 2011.
Handing over18 May 2011.
Cost estimates
The project will cost $100,000 as of its estimated value. The figure includes design, construction and commission, together with the first year of maintenance. Before construction, the survey and design of the project amount to $12,000, which is enough to provide sufficient resources and guidelines for progression to the construction stage. Construction covers the pump station building, which is the most delicate and expensive part of the project, requiring an estimated $28,000 to complete. Two last stages of developing zone A and zone B will cost $18,260 and $17,930 respectively. Thereafter, the project will be ready for commissioning.
Configuration management
The project team emphasises on configuration management because it understands the role it plays in improving the efficiency of construction. For this project, the identified areas of improvement will be the water filtration system installation job, and the marking out of construction zones A and B. These tasks will happen concurrently to save time and utilise all idle resources. When constructing the two zones, a team will be laying out the pipework to have irrigation components connected. The connection of the components will take place immediately zone construction ends. In essence, the plan is to make sure that the next part of the project commences as soon as another part ends, and the delays associated with waiting or transferring work teams through projects will not be experienced.
Approval requirements
The project needs the approval of the client and any local authorities concerned with the licensing of construction, design, and implementation. The project also depends on approval by legal authorities for its commencement, payment, and handing over. The local authority’s approval is necessary before the project begins. The project will have a go-ahead after attaining the approval.
Work breakdown structure
Work breakdown chart
Figure 1: Work breakdown schedule (WBS) chart (Source: author).
Activities and Costs of the project
Table 1: Activities and associated costs (Source: author).
Activity
Project Area
Activity Cost
Initial survey
A&B
$3,200.00
Outlining & design
A&B
$7,500.00
Pumping System setup
A&B
$29,000.00
Delineation of main lines
A
$900.00
Delineation of sub mains (4)
B
$950.00
Excavation (main & 4 sub-mains)
A
$4,000.00
Levelling (main & 4 sub-mains)
A
$2,950.00
Excavation 4 sub-mains
B
$4,000.00
Levelling of 4 sub-mains
B
$2,150.00
Assembly of 4 (60 mm) valve
A
$2,400.00
laying & jointing of (60 mm) pipe
A
$4,100.00
laying & jointing of (75 mm) pipe
B
$4,500.00
Assembly of 3 (75 mm) valves
B
$2,600.00
Simple lateral laying (200 nos)
A
$2,300.00
Simple lateral laying (250 nos)
B
$2,480.00
Mini sprinkler fitting
A
$1,400.00
Online dripper fitting
B
$2.100.00
TOTAL
A&B
$76,230.00
Cost estimates
Figure 2: Cost estimates (Source: author).
PERT Chart
Figure 3: Project PERT Chart (Source: author).
GANTT chart
Figure 4: Project Gantt chart (Source: author).
Recommendations
This project made assumptions and other considerations based on an already implemented project in Pakistan, which presented the case with some information and work-related constraints that should be dealt with in an improved way. Nevertheless, the project has made significant variations to the assumptions to make the project relevant to its adapted remote location of Western Australia. One constraint revealed in the project was the limitation of working hours to 11, which would reduce to 7 hours when electricity would be available. Since many of the tasks cannot take place without electrical power, this limitation serves as the biggest constraint worth manipulating to improve other aspects of the project delivery timeline (Mathis, 2014). The project assumes that remote locations of Australia have power supply issues; therefore, it has to put up with power rationing at times. Given that the power schedule is predictable, it is possible to plan for alternative power sources for the project to ensure that the maximum available hours for work are utilised well. A potential solution is to have a portable generator to provide electricity when the main power goes off.
The generator will have an impact on the overall cost of the project, as it has to use fuel to produce power. However, the team can alter the configuration management to ensure that light electrical works happen when the mains electricity is off whenever possible. This will have an effect of easing the load on the generator to provide lighting on the project location and cover basic electrical needs like powering appliances and tools. Efficient management of the utilisation of the two electricity sources will ensure that the project overhead costs attributed to the inclusion of the generator remain within a small fraction of the total budget. Failure to manage the costs associated with the generator or the switching time from electricity from the mains to electricity from the generator can have a significant negative impact on the total cost and the project timelines.
The project’s WBS chart and Gantt chart present an outlook of work division in its two zones. It is important to show that work on either zone depends on similar work on the other zone. An additional consideration is that this project has only two zones, yet the original one in Pakistan had six zones. In this regard, it is possible to condense works for each zone to similar batches so that the days needed for completing them are cut and the cost involved in using human resources, especially the contracted labour, remains low. An example of batching can be the demarcation of pipelines that at present is indicated as work for two days, yet it can be a single day’s work. This can happen when work on both zones is done concurrently. The task will require a higher number of workers, but it will take only a day, instead of two. Reducing the days creates additional room for shifting other work schedules throughout the project.
For example, the excavation task breaks down into several days so that the excavation team will finish early on each day. One of the reasons is to comply with the restriction on the present working hours. However, there is an opportunity of having the excavation works happening as a single task maximised with enough resources to ensure that it takes the least time possible. Targeting excavation works for condensing is important because it is a groundwork task that is a prerequisite for other tasks. Improving its completion time will reduce overall project time. The rationale of reducing the excavation time is that excavators and their operators will likely be a service billable hourly. It will make little difference in costs to have many excavators and servicemen working at the same time and using less time than to have one working for long. However, the time savings are significant (Wysocki, 2004).
Overall, increasing labourers should lead to the completion of work at an earlier time than scheduled, especially on scalable tasks like laying and joining pipelines, where unskilled labour and semi-skilled labour is required. The expectation is that implementation of these recommendations will lead to significant cost savings and time savings. Saving up for three days for the project can be a required window for the company to move into other projects (Kerzner, 2001). At the same time, the three days can be a buffer used for any delays caused by identified project risks. This could ensure that the project stays on course and meets its timelines as scheduled.
Challenges
The group gave in to many challenges in the course of carrying out the assigned task. One of the challenges was on selecting the project that would be the basis for the assignment. It was necessary to move past this hurdle to accomplish the task.
The group faced difficulties in convening meetings about the project because members had different timetables and would only be available when they had breaks from other obligations. The fact that members of the group had different semester plans did not help. However, after rescheduling of activities and obligations, it was possible to have one day for meetings, wherewith all members comfortable. In the case of absentees, meeting deliberations and conclusions were passed on to the absent members. Overall, most members prioritised the group meetings over other activities to ensure the project succeeded.
The second challenge was finding a project that would provide members with sufficient information resources to use for different parameters of the project. While reviewing potential projects, the group settled for Moomba Gas Plant project that involved construction and commissioning of a compressor station at the project site, but it became apparent that realistic cost estimates based on this project were impossible. The group moved on to the Pakistan project that would allow members to use easily public information to estimate costs.
As the group changed the project midway, it encountered another challenge of time. The time spent on the previous project was a sunken cost, which also became a demoralising factor in the group. However, the time constraint was eased by the availability of all relevant data on irrigation systems around the world, which reduced the time demand for research. At the same time, group members were experienced in research due to their involvement in the previous project. They improved their speed when using research tools to come up with a good project plan.
The original plan employed in Pakistan was complicated, and there was a need to simplify it to meet the time and project constraints of the group and the assignment. There were six zones in the original project, but the group shrunk the project into two zones, so that tasks associated with its design and implementation would be simpler and take less time to accomplish. A simplified project also promised to allow deeper focus into its components and facilitate a greater understanding of the tools used in the project. The group would also avoid the task of analysing a large amount of data at the expense of project completion.
Coming up with accurate cost estimates was tough, but having experienced the difficulties of the research and facing a time constraint after abandoning the previous project seemed to motivate group members to work efficiently. The group settled for quotes of similar tasks online to ensure that there was a unified criterion used in estimating costs. In some cases, elements of the project lacked quotes online, and the group relied on conventional information about service or component costs in the market. The prices came from quotations of farming and agricultural supply companies.
Lesson learned
The group learned some lessons as a result of undertaking this assignment. The lessons included organisational and research skills. Members learned individual and group lessons, which they will be able to use in future study and work assignments.
Organisation and collaboration emerged as important lessons, which were also addressed in the challenges section of this assignment. The group members have learned the importance of effective communication, which should be consistent and considerate of the circumstances affecting the recipient of the message. There was also a lesson in organisation and the need to make self-sacrifices to ensure the completion of a complex task is possible in a group setting. The fact that the group completed most of the final project details in less than the time that was initially allocated was commendable. The team members appreciated the importance of focus, sacrifice, and proper objectives for the group assignment.
The members also learned the importance of delegation of tasks and peered supervision to ensure that the project commences as scheduled and reaches completion in time. Peer monitoring was instrumental in keep members active on their assignments and allowed members not to overlook any aspect of the project. Consistent communication by group members about the project helped to keep the project going at different stages when individual members faced difficulties in their assigned duties. Besides, it allowed members who completed their assigned tasks early to identify areas where they could help in other members’ tasks.
The group learned the need for a well-detailed project plan, which was possible after using a project plan as the basis of planning required tasks. Time allocation and association for each task, together with their respective costs provided project leaders with a detailed perspective on the work at hand. A project plan is an important tool because it serves as a checklist for all the tasks needed and their priority at different times of project implementation. The project plan ensures that all the work planned in a project is completed. It also gauges whether the project implementation team will honour completion times. The team can also use the plan to have a precise cost estimate in a detailed way so that the available funds are allocated in a judicious way and only used when required (Melton, 2008).
The use of a visual method in displaying the work breakdown schedule was instrumental in improving the understanding of tasks and their time allocation, as well as the importance in the overall project. Readers can easily use the graphical representation to visually attach costs and resources to different tasks without having to interpret large blocks of text. In this regard, the WBS Chart and PERT or Gantt charts for the whole project are useful tools for disseminating project information to different audiences in a succinct way. Moreover, the Gantt chart works well to keep all project members updated and involved in a project because it eases any confusion that might arise about project deliverables and work allocation (Lester & Lester, 2007). Members can see how individual tasks play an independent or collective role in moving the project forward. A PERT chart complements the Gantt chart and extends the details on particular tasks in a project, with an emphasis on scheduling so that a technical team can have the necessary information for proceeding with other aspects of project planning and implementation. The PERT chart highlights dependencies of tasks presented in the WBS (Lock, 2007).
Conclusion
Accomplishing the project as a group allowed group members to learn an important lesson in project management practically. The main lesson was that there was a need for routine group interaction and collective effort. This assignment required the group to come up with a detailed project plan for either an existing project or makeup one. Group 31 opted to come up with a fictional project plan. The plan was based on an existing project in Pakistan. However, the fictitious plan only used the core elements of the copied project and scaled it down to meet the group’s project constraints.
The completion of this assignment impacted the group members positively. The group had practical lessons on fundamentals of a project plan and the role it plays in the field of engineering, as well as the successful application of learned lessons and theories into practice. This happened through the implementation of the various components of project planning as required by the assignment. The result has been a clear understanding of project planning, which will be instrumental in ensuring the success of other project done by the group or its members.
References
Blanchard, B. S. (2004). System engineering management. Hoboken, NJ: John Wiley & Sons.
A general-purpose assembly is an enclosed region occupied by at least fifty people and above performing special functions such as entertainment, worship, and deliberations. Due to the large number of people who are usually hosted in a general-purpose assembly, safety is of great importance.
Proper water flow requirements in a general-purpose assembly begin with regular inspection of sprinklers so that any impairment can be noted in advance. While some impairment in the water flow system may not go for too long, there are instances when such impairments may be experienced for over 10 hours (NFPA, 2004). If the latter happens, it is highly advisable to evacuate occupants from the affected spots. In addition, the affected area should be supplied with a temporary flow of water alongside keeping a strict vigil on any possible fire outbreaks. Moreover, an assessment of the fire control program should be initiated and approved whenever impairments are noted within the water flow systems.
Typical inspection of water sprinklers for an NFPA 25 fire protection system is also part and parcel of requirements for proper water flow. For instance, water sprinklers may be leaking thereby exposing room occupants to more dangers in the event of fire outbreaks. Any leakage in the sprinklers also reduces the optimum pressure required (for water) when putting out fires. Leakages may equally cause dampness in halls used by occupants.
Water sprinklers should also be free of corrosion. Corroded sprinklers are not effective for use in any water flow system because they may cause serious leakages during the fire fighting operations (Koffel, 2011). This implies that metallic sprinklers ought to be painted regularly. Water sprinklers should also undergo inspection to ensure that they are properly loaded and well oriented. In other words, sprinklers should be fully loaded with the right volume of water and positioned in such a way that they can be accessed easily during fire outbreak emergencies. Clearance below sprinklers and empty bulbs are part of the proper water flow requirement within a general-purpose assembly.
In order to ascertain the proper flow of water, standard typical sprinkler testing should be carried out on all the established water systems. For example, after installing and using a new sprinkler for 50 years, it should be tested by the concerned experts. Similar tests should follow at intervals of 10 years. Unless such measures are put in place, proper water flow in fire protection systems cannot be guaranteed. For fast-response sprinklers, testing should be carried out 20 years after the first installation. If the system is found to be faulty, it may be replaced or repaired. Similar tests or replacements should follow 10 years later for fast-response water sprinklers (Fire Sprinkler System Maintenance and Testing, n.d). For dry sprinklers, it is highly recommended that testing or replacements should be carried out within an interval of ten years. However, outdoor sprinklers that may be subjected to harsh environmental conditions such as extreme heat or cold are supposed to be tested or replaced after every five years.
When carrying out the tests, the focus is on either 1% of the sample region or four sprinklers (Beattie, 2012). The test sample which is larger is usually preferred. In the case of antifreeze solutions, yearly tests are recommended. Water systems should be located in strategic locations to sprinklers. Other core requirements include the concentration of water being used, system pressure, and spray distribution pattern.
This method was chosen for the Arzaville neighborhood stormwater runoff because it is simpler to implement, less expensive, and environmentally acceptable. It was taken into account because it provides greater imperiousness, where the rising development of Arzaville community structures and roadways disrupts the local water cycle and floods bays and guts with significant amounts of stormwater and associated toxins. In addition to preventing the runoff of stormwater, rain gardens provide a habitat and food for wildlife, which include insects such as butterflies, enhancing the beautification of Arzaville yards (Sheffield et al., 2018). Generally, rain gardens were fit for implementation as they would enhance soil moisture, prevent flooding, and beautify the Arzaville area.
This design element was picked because it does not produce “heat islands,” areas of pavement that appear to be significantly warmer than the surrounding regions. The concept was accounted for because it allows for using recycled materials in its construction, reducing the need for the external landscape to produce resources to build roadways and pavements. Some benefits of the permeable pavement system include catching precipitation and surface runoff, allowing the water to slowly infiltrate the soil through drain tiles (Sheffield et al., 2018). This system can be integrated into Arzaville parking lots, sidewalks, traffic roads, and driveways as it promotes water storage in reservoirs.
This solution was chosen because it is a practical and popular water recycling system for the expanding Arzaville community. Additionally, it provides advantages like cost savings because installation is less expensive, a reduction in snowfall, and proof of industrial expansion. Moreover, gray water is essential as it contains vital nutrients which can be channeled to the plants that grow in Arzaville (Sheffield et al., 2018). Some of the gray water might be from fertilizer industries, which might boost the soil quality in Arzaville if the water’s runoff is maintained within environmental standards, such as the 2-inch-height-above-the-ground runoff trench construction.
Groundwater quality in many countries has special significance and needs great attention of all concerned since it is the major alternate source of domestic, industrial and drinking water supply. The present study monitors the ground water quality, relates it to the land use / land cover and maps such quality using Remote sensing and GIS techniques for a part of Western Cape, South Africa metropolis. Thematic maps for the study are prepared by visual interpretation of SOI topo-sheets and linearly enhanced fused data of IRS-ID PAN and LISS-III imagery on 1:50,000 scale using AutoCAD and ARC/INFO software.
Physico-chemical analysis data of the groundwater samples collected at predetermined locations forms the attribute database for the study, based on which, spatial distribution maps of major water quality parameters are prepared using curve fitting method in Arc View GIS software. Water Quality Index (WQI) was then calculated to find the suitability of water for drinking purpose. The overall view of the water quality index of the present study area revealed that most of the study area with > 50 standard rating of water quality index exhibited poor, very poor and unfit water quality except in places like Banjara Hills, Erragadda and Tolichowki. Appropriate methods for improving the water quality in affected areas have been suggested.
Introduction
The urban environment quality is fading day by day with the largest cities reaching saturation points and unable to cope with the increasing pressure on their infrastructure. Rooiberg Winery is situated on the scenic R60 route that connects the Western Cape (South Africa) towns of Robertson and Worcester. North latitude is facing a rapid change in the environmental quality. Rapid urbanization brings with it many problems as it places huge demands on land, water, housing, transport, health, education etc. Environmental pollution has reached alarming levels in the last 5-6 years mainly due to industries and automobiles.
The city witnessed an increase in population from 0.448 million in 1901 – 1.429 million in 1961, between 1981 and 1991 the population went upto 4.34 million and the growth rate so far is 67.04%. As per the population estimates,This rising population density will continue to have an impact on the quality and quantity of local water resources.
Fresh water being one of the basic necessities for sustenance of life, the human race through the ages has striven to locate and develop it. Water, a vital source of life in its natural state is free from pollution but when man tampers the water body it loses its natural conditions. Ground water has become an essential resource over the past few decades due to the increase in its usage for drinking, irrigation and industrial uses etc. The quality of ground water is equally important as that of quantity.
Remote sensing and GIS are effective tools for water quality mapping and land cover mapping essential for monitoring, modelling and environmental change detection. GIS can be a powerful tool for developing solutions for water resources problems for assessing water quality, determining water availability, preventing flooding, understanding the natural environment, and managing water resources on a local or regional scale. Keeping this in view, we have Integrated Remote Sensing, GIS and field studies for the evaluation of the impacts of land use changes on the ground water quality of zone-V under MCH.
So How Much Ground-Water Do We Have?
In total, some 235,5 billion cubic metres of groundwater may be stored in aquifers in South Africa. Of course, not all of it is usable and can be abstracted. There are many limitations to the possible abstraction of groundwater for use, for example, restrictions to ensure enough water for the environment (the Ecological Reserve), and restrictions on the maximum level drawdown in dolomitic aquifers due to the hazard of sinkhole formation or avoiding intrusion of saline water.
The groundwater resource potential is the maximum volume (m3) of groundwater that can be abstracted per unit area per annum without causing any long-term ‘mining’ of the aquifer system (i.e. without continued long-term declining water levels). It is not equivalent to the sustainable or optimal yield of the system, which normally takes into account issues such as intrusion of poor quality water, practical and cost issues relating to extracting the water and so forth. The average groundwater resource potential of aquifers in South Africa is estimated under normal rainfall conditions at 49 billion m3/a, which decreases to 42 billion m3/a during a drought.
For general planning purposes, it is recommended that the average utilisable groundwater exploitation potential volume be adopted. It is interesting to note that only about 20% of this volume is currently being abstracted on an annual basis
Groundwater Resource Potential
The Groundwater Resource Potential (GRP) is defined as the maximum volume (m3) of groundwater that can be abstracted per unit area per annum without causing any long-term ‘mining’ of the aquifer system (i.e. without continued long-term declining water levels). The GRP is based purely on physical inputs / outputs and aquifer storage. It is therefore not equivalent to the ‘sustainable’ or ‘optimal’ yield of the system, which normally takes into account factors such as intrusion of poor quality water, variable aquifer permeability, practical and cost issues relating to extracting the water etc.
Two basic algorithms have been developed to determine the GRP based on the
average or steady-state (AGRP) and
dynamic or transient-state aquifer conditions.
The steady-state Groundwater Resource Potential dataset is similar to DWAF’s Harvest Potential map in that they both provide estimates of the maximum volumes of groundwater that are potentially available for abstraction on a sustainable basis, and only take into consideration the volumes of water held in aquifer storage and the recharge from rainfall. The feasibility of abstracting this water is limited by many factors due mainly to the physical attributes of a particular aquifer system, economic and/or environmental considerations.
One of the most important of these is the inability to establish a network of suitably spaced production boreholes to ‘capture’ all the available water in an aquifer system or on a more regional scale (Water Systems Management, 2001). The factors limiting the ability to develop such a network of production boreholes, include, inter alia, the low permeability or transmissivity of certain aquifer units, accessibility of terrain to drilling rigs, unknown aquifer boundary conditions.
Groundwater Exploitation Potential
In order to account for the pumping limitations discussed above, the GRA2 project made use of Haupt’s (2001) concept of an ‘Exploitability Factor’ or EF and Vegter’s (1995) national ‘Borehole Prospects’ coverage to generate a 1x1km EF grid for the country. Vegter stated that the prospects of obtaining a groundwater supply from a particular lithological unit may be judged by analysis of the yield distribution of an adequate number of randomly spaced boreholes drilled into this unit. He classified the lithostratigraphic units of the country into 16 water-bearing categories and analysed the yield information from 120,000 boreholes obtained from DWAF’s NGDB. The Borehole Prospects coverage is therefore an indication of the extent to which various lithological units are able to act as aquifers.
The EF factor was applied to the AGRP grid to produce the so-called ‘Average Groundwater Exploitation Potential’ or AGEP coverage. The total AGEP of aquifers in South Africa is estimated at 19,073 Mm3/a, which declines to 16,253 Mm3/a during a drought. It is likely that, with an adequate and even distribution of production boreholes in accessible portions of most catchments or aquifer systems, these volumes of groundwater may be annually abstracted on a sustainable basis.
Groundwater quality is one of the main factors restricting the development of available groundwater resources. Although there are numerous problems associated with groundwater quality, some of which are relatively easily remediated, high concentration of total dissolved solids, nitrates and fluoride are considered to be the most common and serious problems associated with water quality on a regional scale.
Potable Groundwater Exploitation Potential
The Potable Groundwater Exploitation Potential (PGEP) of aquifers in South Africa is estimated at 14,802 Mm3/a, which declines to 12,626 Mm3/a during a drought. Nationally, this represents almost a 30% reduction in the annual volumes of available groundwater for domestic supply due to water quality constraints.
The volume of water that may be abstracted from a groundwater resource may ultimately be limited by anthropogenic, ecological and/or legislative considerations, which ultimately is a management decision that will reduce the total volume of groundwater available for development – referred in the GRA2 project as the Utilisable Groundwater Exploitation Potential (UGEP). This includes the important legislative restriction imposed on the volumes of groundwater available for utilisation by the requirements of the ‘Groundwater Component’ of the Reserve as stipulated in the South African National Water Act of 1998. Other aspects such as protection against the hazards of saline intrusion or sinkhole formation, conserving important groundwater dependant ecosystems, maintaining base flow to rivers etc. can all be factored in using this approach.
The Utilisable Groundwater Exploitation Potential (UGEP) under normal rainfall conditions and under drought conditions is estimated at 10,353 and 7,536 Mm3/a, respectively. The UGEP represents a management restriction on the volumes that may be abstracted based on the defined ‘maximum allowable water level drawdown’ and therefore it is always less than or equal the AGEP. It is likely that, with an adequate and even distribution of production boreholes in accessible portions of most catchments or aquifer systems, these volumes of groundwater may be annually abstracted on a sustainable basis.
Study Area
The mapping area lies between latitudes 33° 40′ 45″ – 33° 30′ 12″ N and longitudes 21° 22′ 24″ – 21° 23′ 05″ E and covers an area approximately 766 km2. Ladismith is located in the Western cape region about 400 km east of Cape Town. The Rooiberg Mountain range sits in the Klein Karoo region Between the Groot Swartberg and the Lange Berg. The area was chosen because of its environment and its dependency on groundwater, especially by the many farms located within the Rooiberg catchments. The Rooiberg Mountain range is part of the centrepiece of the Cape Fold Belt (CFB) and represents an anticlinal structure. Geologically the mapping area comprises of the harder Table Mountain Sandstone (TMS) and the softer shale’s of the Bokkeveld groups.
Table 1: Important features relating to the study area.
Geographic Location
Lat. 33° 40′ – 33° 30′ Lon. 21° 22′ – 21° 23′
Mapping Area
766 km2
Climate
Semi-arid with Winter rainfall. Avg. 300 mm/a. Hot Summers Avg. 32°c – Winters Avg. 15°c
Physiography
High Relief with gentle to steep rising slopes. Varied elevation, ranges from 170m – 1490m above MSL
Lithology
Mainly quartzitic sandstone, shales and siltstones of the Permo-Triassic Cape Fold Belt Orogeny
Economic Activity
Agriculture, Horticulture and Conservation
Methodology
In this present study, the methods used follows a combination of techniques already used in previous studies of a similar nature. Various datasets and maps (Table 2) of different scales were used. In order to demarcate groundwater potential zones, thematic maps were created either from remote sensed or from conventional field data. All the data that wasn’t in a digital format was digitized and spatial database was developed. Those thematic maps created from remote sensing included:
geology,
Landforms and
Lineaments.
The remote sensing data was acquired from the NASA Multispectural Scanner Landsat 2000 Geocover collection (spectral range 0.450 – 2.35 µm), path 173 / row 83. The secondary base maps of
Drainage density,
Slope and
elevation were prepared from 1:50 000 scale topographic maps of the Ladismith region (3322CB).
Digital topographic maps of the area were acquired from the Chief Directive Survey and Mappings based in Cape Town, South Africa. Other supportive data such as boreholes and spring locations (GPS) were collected out in the field. Other miscellaneous data like borehole levels and rainfall data (appendices) were collected from the local farmers. All suitable field data was digitized and included during the preparation of the thematic maps.
In order to create the spatial database, the ESRI ArcGIS (ArcMap 9.2, ArcCatalog and ArcScene) software was utilised during the integrated analysis. ArcCatalog was used extensively in building and managing the spatial database. ArcMap 9.2 with the ‘Spatial Analyst’ extension was used for creation and analysis of the thematic maps. ArcSecne was used to build a 3D representation of the study area in conjunction with the topography. The development of the thematic maps follows the similar methods used by Kumar et al. (2007), Krishnamurthy et al. (1996) and Saraf et al. (2000), all the base maps were geo-referenced to a common reference point.
This was done by using the 1:50 000 topographic map of the Ladismith region, using ground control points common to all maps (ESRI 2008). Thematic maps such as geology, lineaments and landforms were derived by visual interpretation of the Landsat 2000 Geocover. All the thematic maps were digitized in the vector format whereby the values of the polygons were edited and labelled. After this a multi-criteria evaluation technique (Chi & Lee, 1994) was used to assign weightings and scores to the various thematic map themes depending on the features influence on groundwater occurrence (Table 3).
The suitable weights were determined by the various groundwater-controlling parameters (Table 4). For example, in this study geology plays a vital role in groundwater storage followed by landforms, lineaments, drainage density, slope and then elevation. The total weight of 100 was divided between the themes, whereby geology was assigned a maximum of 45 and a minimum of 5 was assigned to elevation and so on (See map algebra). All the themes and features were then converted into raster format using the ‘Spatial Analyst’ extension of ArcMap 9.2. The scores of the individual features were entered in the value field and all the themes were overlaid two at time by using the ‘Weighted Sum’ tool in ArcMap 9.2. The final groundwater potential zone map was classified from very good to very poor. The location of boreholes and springs were used to correlate this output. The steps for the methodology are shown in flowchart (figure 3).
Groundwater Potential Map (GPM) = (Geology) x 0.45 + (Landforms) x 0.25 + (Lineaments) x 0.10 + (Drainage De Methodology.
Table 2: Various datasets used in the study.
Type of Data
Description of data
Source of data
Topographical maps
3321CB of Van wyksdorp 3322CB of Ladismtih Surveyed: 1981-1982 Digital format. Scale 1:50 000
University of Maryland: Global Land Cover Facility
Borehole and spring Locations
Field work, acquired July – August 2007
12 Channel GPS receiver
Geology
In the study area, the Table Mountain and Bokkeveld groups underlie most of the Klein Karoo. The majority of the rocks that form the Table Mountain Group (TMG) are made up of medium-grained quartzites and sandstones. The TMG comprises of the Upper and Lower Table Mountain Sandstones and that of the Pakhuis formations. The Pakhuis formation is situated between the lower and upper TMS and comprises mainly of shales and diamictites. The Pakhuis formation is less competent than the TMS sandstone and quartzite and so is more susceptible to weathering.
In contrast to the TMS, the rocks of the Bokkeveld are also less competent than the TMS. They consist mainly of sandstone, shales and massive quartzites that make up most of the ridges seen in remote sensing. On the mapping area the Bokkeveld group is divided into eight subdivisions, field information and the geological map were used to distinguish the different rock units from each other. Very few of the formations are made up of one type of rock, the sandstones, shales and quartzites appear in many formations but in different orders, ratio and relation.
The different geologic units were outlined from the remote sensing images by the distinct characteristics. On the False Colour Composite (FCC) image, the TMG was identified on the image by areas of reddish-brown to blue colour/tone with medium to fine texture, very distinct on the northern slope of the Rooiberg. The Bokkeveld formations were demarcated by the bluish-brown to green in colour and tone. The presence of shale shows up to medium to coarse in texture, owing to weathering and surfaces of the shale composition. Alluvium was clearly outline by the reddish colour from the vegetation and the light-yellow colour/tone of the sediments. Bare surfaces such as roads and low lying areas appeared white on the FCC image.
Borehole information
Most of the previous work has been in the western and central parts of the Karoo Basin, which has only a small fraction of the population of the eastern part. Although thousands of boreholes have been drilled in the eastern parts, the data, such as borehole depths, depths of water strikes, drilling yields, etc, does not exist in a useful and readily available format. In order to develop reasonable conceptual models describing the occurrence and flow dynamics of groundwater in the Eastern Karoo Basin, this data will need to be captured in a manner that enables spatial and statistical analysis.
Borehole and groundwater information (data capture and analysis)
The collection of appropriate data is essential not only for research purposes but also for the day-today aquifer management, as well as for developing long-term water resource planning strategies. In relation to groundwater occurrence, borehole information including depths, water strikes, drilling yields, geology and water quality needs to be captured in a spatially and statistically useable format.
This will require updating and integrating various data sets, including the older National Groundwater Database (NGDB) and its replacement the National Groundwater Archive (NGA), as well as local initiatives such as the Eastern Cape Province’s Groundwater Information (GRIP) Project. In relation to sustainability, water level, abstraction and water quality time-series data needs to collected. This information is crucial if aquifers are to be developed to their maximum capacity and managed in a sustainable manner. The following types of questions need to be addressed: What data should be collected, and how often? How should the data be assessed and presented in order to
Groundwater Research Needs i n the Eastern Karoo Bas in of South Africa
May 2006 provide useful information for Water Service Authorities? What other support in terms of data collection and analysis can groundwater professionals provide to the Water Service Authorities?
Landforms
Effectively, landforms act as surficial indicators to groundwater potential. Each landform is different physiographically and the genesis and processes of different geomorphic units is determined by the underlying lithology, slope and the type of drainage pattern that exists (Saraf, 1999). Again the recognition of the various landforms were outlined according to tone, texture, size and shape. In total seven geomorphological units were identified. In the centre of the mapping area is the eastern section of the Rooiberg range with steep rising slopes that represents an anticlinal structure caused by compression during the CFB orogeny. To the south and north are the undulating hills of the Bokkeveld.
The landforms that were mapped from the remote sensing images: Linear Ridges, Denudo-Structural Hills, Structural Hills, Residual Hills, Residual Mount Complexes, Pediplains, Valley Fill and Alluvial Fill.
Linear Ridges: Very few linear ridges are found in the mapping area, those that fall within the mapping area were located in the upper TMS of the Rooiberg. Its linear feature, steep slopes and reddish-brown to blue in colour and tone identified this landform on the FCC. Anticlinal and synclinal folding shows up as long linear parallel ridges and valleys.
Denudo-Structural Hills: A main linear ridge that runs in an E-W trend separates the denudation-structural hills, which is present only in Rooiberg itself. These features can be separated into a southern complex and a northern complex. These were delineated by the homogenous structural shape, ruggedness and reddish-brown to bluish-purple in colour/tone on the FCC. Other identifiable features from this landform are its medium to fine texture and areal extent in terms of its drainage density.
Structural Hills: Structural hills at the base of the Rooiberg to north and south are made up Boplaas Bokkeveld and Witterberg formations. The section of hills in the northwest corner of the mapping area consists of Wagen Drift Witterberg. Since the major rock types of these subdivision consists of sandstones, quartzites and siltstones with thin interlayers of shale, on the FCC the colour/tone of these features show up as reddish-brown. Theses hills are also identified by the medium texture with bedding traces, saddles strike ridges and structurally controlled drainage.
Residual Hills: These are found mostly in the southern part of the mapping area. Delineated by their detached, isolated nature with gentle slopes that show little folding. Residual hills are features from the end process of pediplination; they represent the reduction of the original mountain masses in the form of scattered hillocks on the Pediplains (Thornbury, 1990). Their structural shape, coarse to medium texture and dark red-green in colour and tone on the FCC, determined the identification of residual hills.
Residual Mount Complexes: These mount complexes are formed by the prolonged erosion and weathering of pre-existing surfaces and original complex tectonic mountains. Collectively they form a complex of hills whereby the lithology varies in accordance with the competency of the rock. These complexes are found to the northwest and south of the mapping area. They were identified by variation of colour/tone from bluish-green to red. Again the textured also varied, those complexes in the south were found to be coarser owing to the lack of vegetation, whereas those complexes in the northwest were coarse to medium indicating more vegetation coverage. Structure and shape show the mount complexes not to have a structurally controlled drainage pattern although faulting is present.
Pediplains: These features are gently undulating landscapes that sit between isolated residual hills and complexes. They vary in material and thickness covered by soil that originates from weathered material from the surrounding uplands. On the FCC the colour and tone of the Pediplains varied from white to greenish-blue and even from reddish-black owing to the soil cover. Again the texture is seen to be coarse-medium to even fine in the north section of the mapping area. These plains are situated mostly in lower-lying areas of the Bokkeveld, below the TMS.
Valley Fill: This feature is characterised by unconsolidated alluvial and or colluvial material. Mostly situated within the Rooiberg itself on both the northern and southern flanks of the range. These areas are characterised by their broad to narrow structural drainage patterns. The dense vegetation that shows up to be bright red on the FCC with a coarse texture easily distinguishes the identification of valleys.
Alluvial Fill: Characterised by meandering river channels that are perennial in the mapping area. These are found in the northwest/east corner and directly south of the Rooiberg in the mapping area. The unit shows up on the FCC with a smooth greyish-white texture from the sediments and also red in colour/tone from vegetation.
Lineaments
Lineaments act as pathways for ground water movement and are very important hydrogeologically (Kumar et al. 2007). They appear as large-scale linear features that are generally manifested by topography. The geological structure normally encountered in hardrock areas of places such as Africa and India is granite or granite gneiss overlain by a variable thickness of weathered material (Barker, 2001). Area and zones of hard rock terrain that contain lineaments, represents faulting and fracturing that results in increased secondary porosity and permeability. Hence this is why the majority of the large-scale lineaments are found within the TMS due to intense deformation. They pose as important structures for governing recharge, migration, and discharge of groundwater (Fetter, 1994).
A total of 86 major lineaments were identified in the mapping area with lengths varying from hundreds of meters to tens of kilometres. The lineaments can be broken up into those in north of the Bokkeveld (total = 23, NW-SE trend), that of Rooiberg TMG (total = 49, EW, NW-SE and NE-SW trend) and the rest in the south of the Bokkeveld (total = 14, NW-SE trend). By observing the lineament directions and lineaments intersections, it is evident that the structural patterns of the landforms are directly influenced.
Drainage Density
Significance of drainage pattern
The drainage system, which develops in an area, is strictly dependent on the slope, the nature and attitude of bedrock and on the regional and local fracture pattern. Drainage, which is easily visible on remote sensing imagery, therefore reflects to varying degrees the lithology and structure of a given area and can be of great value for groundwater resources evaluation. Drainage is studied according to its pattern type and its texture (or density of dissection) (Way, 1973).
Whilst the first parameter is associated to the nature and structure of the substratum, the second is related to rock/soil permeability (and, thus, also to rock type). Actually, the less a rock is permeable, the less the infiltration of rainfall, which conversely tends to be concentrated in surface runoff. This gives origin to a well-developed and fine drainage system. On the other hand, in karst regions, where the underground circulation of water is much more developed than the surficial one, drainage is less developed or missing altogether.
Six basic types of drainage patterns were identified, namely: dendritic, trellis, parallel, radial, anular and rectangular. Their features and occurrence are as follows (Way, 1973):
In the dendritic pattern, a tree-like branching of tributaries join the mainstream at acute angles. Usually this pattern occurs in homogeneous rocks such as soft sedimentary or volcanic tuffs.
Trellis is a modification of dendritic, with parallel tributaries converging at right angles. It is indicative of bedrock structure rather than material of bedrock. It can be associated to tilted or interbedded sedimentary rocks, where the main channels follow the strike of beds.
In the parallel pattern, major tributaries are parallel to major streams and join them at approximately the same angle. It can occur in homogeneous, gentle and uniformly sloping surfaces whose main streams may indicate a fault or fracture zone. Common in pediment zones.
The radial pattern is a circular network of approximately parallel channels flowing away from a central high point. It usually occurs in volcanoes or domelike structures characterized by resistant bedrock.
Anular pattern is a concentric network of channels flowing down and around a central high point. This pattern is usually controlled by layered, jointed and fractured bedrock, in granitic or sedimentary domes.
The rectangular is a modification of the dendritic pattern, with tributaries joining mainstream at right angles, forming rectangular shapes. It is controlled by bedrock jointing, foliation and fracturing, indicative of slate, schist, gneiss and resistant sandstone.
Further modifications of the six basic schemes give origin to more than 20 other patterns that cover almost all the possible existing cases.
In addition to the pattern characterization, drainage can also be described in terms of texture or density of dissection. On this basis, three types can be identified: 1) fine, which is indicative of high levels of runoff, suggesting impervious bedrock and/or fine textured soils scarcely permeable; 2) medium, which can be related to a medium runoff and mixed lithology, and 3) coarse, which indicates little runoff and consequently resistant, permeable bedrock and coarse, permeable soil materials.
Data interpretation
Data Used
Different data products required for the study include the 56K/7 and 56K/11 toposheets which are obtained from Survey of India (1:50,000) and fused data of IRS – 1D
PAN and LISS-III satellite imagery of path 100 and row 60 from National Remote Sensing Agency (NRSA), south Africa.
Database Creation
IRS-ID PAN and LISS-III satellite imageries are geo-referenced using the ground control points with SOI toposheets as a reference and further merged to obtain a fused, high resolution (5.8m of PAN) and coloured (R,G,B bands of LISS-III) output in EASI/PACE v6.3 Image processing software. The study area is then delineated from the fused data based on the latitude and longitude values and a final hard copy output prepared which is further interpreted visually for the generation of thematic maps.
These thematic maps (Raster data) are converted to vector format by scanning using an A0-Flatbed DeskJet scanner and digitized in AUTOCAD 2000. The map is further edited in ARC/INFO v3.5.1 and final hardcopy output is prepared using ARC/VIEW v3.1 GIS software. The methodology adopted for creation of database is given in
Figure 1: Flow chart showing the methodology adopted for the generation of database.
Spatial database
Thematic maps like base map and drainage network maps are prepared from the SOI toposheets on 1:50,000 scale using AutoCAD and Arc/Info GIS software to obtain a baseline data. All the maps are scanned and digitized to generate a digital output. Land use/Land cover map of the study area was prepared using visual interpretation technique from the fused satellite imagery (IRS-ID PAN + LISS-III) and SOI toposheets along with ground truth analysis.
Attribute database
Fieldwork was conducted and groundwater samples were collected from predetermined locations based on the land use change and drainage network maps of the study area. Map showing sampling points overlaid on satellite imagery as shown in Fig 2. The water samples were then analyzed for various physico-chemical parameters adopting standard protocols.
Figure 2: Sampling points overlaid on satellite imagery.
Integration of Spatial and Attribute Database
The spatial and the attribute database generated are integrated for the generation of spatial distribution maps of selected water quality parameters like pH, alkalinity, chlorides, sulphates, nitrates, TDS, total hardness, fluorides and Water Quality Index (WQI) and overlaid on satellite imagery. The water quality data (attribute) is linked to the sampling location (spatial) in ARC/INFO and maps showing spatial distribution are prepared to easily identify the variation in concentrations of the above parameters in the ground water at various locations of the study area using curve fitting technique of ARC/VIEW GIS software. Spatial Modelling and Surface Interpolation through IDW
GIS can be a powerful tool for developing solutions for water resources problems for assessing water quality, determining water availability, preventing flooding, understanding the natural environment, and managing water resources on a local or regional scale. Though there are a number of spatial modelling techniques available with respect to application in GIS, spatial interpolation technique through Inverse Distance Weighted (IDW) approach has been used in the present study to delineate the locational distribution of water pollutants or constituents. This method uses a defined or selected set of sample points for estimating the output grid cell value. It determines the cell values using a linearly weighted combination of a set of sample points and controls the significance of known points upon the interpolated values based upon their distance from the output point thereby generating a surface grid as well as thematic isolines.
Results and Discussion
The GIS-Based model in the present study uses logical conditioning and follows that of other models used in previous and similar studies (Chi & Lee, Krishnamurthy et al. 1996, Saraf et al., 1999 and Murthy, 2000). Before the thematic layers could be integrated with one another, each theme had to be weighted and scored. This relative ranking was based on pros and cons of the particular themes characteristic in terms of groundwater occurrence. The scores and weights ranged from
50 – Very good,
40 – Good,
30 – Moderate,
20 – Poor and
10 – Very poor.
For instance, an area that varies in landforms can be assigned various scores, such as for a level surface with unconsolidated material will be given a higher importance than an area with a steep impermeable slope. Similarly, areas that are characterised by more weathered /fractured geology is scored higher than that with compact and less weathered/fractured rock. After the categorisation, all the themes were converted to raster format using the ‘Spatial analyst’, tool in the ArcMap 9.2 software.
During the raster conversion, all the scores and weights assigned to the individual features were logged in the value field. In order to demarcate different groundwater potential zones, the six thematic layers were integrated according to their importance by a technique called ‘combinatorial method’. This is a type union function, whereby the function combines multiple rasters so that a unique output value is assigned to each unique combination of input values.
The names of the input rasters are assigned to the item names. Each of these items carries the unique input combination of values from the input rasters that produce the output value. These items retain the parentage that was used to produce the values for the output raster (ESRI, 2008). Finally by dividing theme weights by 100 based on importance normalized the individual themes, this was done instead of just dividing the maximum and minimum values into different categories. The outline for the combine sequence is shown in table 5.
In the first step, geology (L1) and the landforms (L2) layers were overlaid with one another to create the (R1) layer (Basically the resultant output of the two). The (R1) layer was then joined with the lineaments (L3) layers to produce (R2). The resultant layer of R2 was integrated with drainage density (L4) and so on until all six layers had been combined. The end product layer was that of (R5) which had a maximum score of 300 and a minimum of 60. Again the attribute values were checked and labelled in the final raster layer.
The final thematic map score values were then reclassified to show five classes of groundwater potential zones. These zones were very good, good, moderate, poor and very poor. Each of the five classes fell between an upper limit and a lower limits, this is shown in table 6.
The zones classed as ‘very good’ for groundwater potential fall between the upper limits of 300 and the lower limits of 240. Similarly the zones classed as ‘good’ were delineated between 240 and 180. This process was then repeated for the rest of the classes.
Table 5: Grouping of layers and total weights.
Thematic Layers
L1
L2
L3
L4
L5
L6
Total Weights
Category
50
50
50
50
50
50
300
Very good
40
40
40
40
40
40
240
Good
30
30
30
30
30
30
180
Moderate
20
20
20
20
20
20
120
Poor
10
10
10
10
10
10
60
Very poor
The final thematic map shows the study area with all the integrated layers. In the north, it indicates that the area in and around the structural hills, lineaments and mount complexes tends to have ‘very good to ‘good’ groundwater potential. Moving east along the north section of the map, it changes from ‘good’ to moderate where it reaches a Denudation hill in the northeast. Here the geology and slope alters from the Bokkeveld groups to TMS with a rise in elevation of around 500m to 1000m. There is also a decrease in the amount of lineaments in this section o the map. Focusing on the centre of the map and that mainly of the Rooiberg mountain range, groundwater potential starts to drop.
The predominant landforms here are Denudational structures with steep slopes and linear ridges. Here the geology is TMS with elongated, fractured and jointed features. These structures form much of the Rooiberg catchments area, valleys are present in-between them. Many of the valleys are situated on top of or around large substantial lineaments. The groundwater potential ranges from ‘poor’ to ‘very poor’ on the slopes of the Rooiberg and the high peaks of linear ridges.
However, the valleys offer ‘moderate’ to ‘good’ groundwater potential based on the drainage density and lineaments zone of influence. South of the Rooiberg the groundwater potential varies. Towards the southwest of the study area moving down from the Rooiberg into the lower formations of the Bokkeveld, the majority of the area is covered with residual hills with some structural hills and a residual mount complex farther south. Residual hills are far less spatially extensive than that of structural hills and the areas in-between these landforms are pediplains that are undulating surfaces consisting of broken up material of varying thickness.
These landscapes offer high permeability and porosity owing to the unconsolidated material. The groundwater potential here ranges from ‘moderate’ to ‘good’. In the southwest of the map, an alluvial plain that consist of Tertiary to Quaternary material (Le Roux, 1983) offers the potential to be ‘good to very good’ whereas the surrounding area is then a mixture of Wuppertal and Wagen Drift Bokkeveld formations dropping the potential from ‘poor to very poor’. Moving to the southeast section of the map, a mixture of potential ‘moderate to poor to very poor’ groundwater is present. Although there is a relatively high drainage percentage in this area, the geology varies from TMS to Bokkeveld mount complexes with the majority of these landforms having steep slopes.
The total area calculated for the groundwater potential zones were:
Very Good – 124.4 km2,
Good – 179.47 km2,
Moderate – 114.77,
Poor – 170.9 km2 and
Very Poor – 92.9 km2.
Table 6: Upper and lower limits the final weights.
No.
Category
Upper Weight
Lower Weight
1
Very Good
300
240
2
Good
240
180
3
Moderate
180
120
4
Poor
120
60
5
Very Poor
60
0
Module evaluation and field checks
Filed checks were carried out to ascertain the validity of the studies ‘groundwater model’. The model was checked against borehole and spring-seepage data (appendices), which reflects the status of the current groundwater potential. In total, seven borehole and two natural spring locations were recorded by acquiring their GPS coordinates, the local farmers gave the historic data for their own boreholes and springs. Other such data that was included in the observation was taken from groundwater abstraction test carried out on the Outspan farm in 2001 (21 15 17.77” E, 33 36 35.95”S) by the Ground Water Consulting Services. However, this data only reflects the groundwater potential to a certain extent in the study area and doses not represent all the groundwater potential ‘classes’.
The boreholes to the east and north of the Rooiberg are drilled to around 70m – 150m in the depth. Groundwater levels here are pumped at around 100m plus. The remaining four boreholes south of Rooiberg are drilled between 70m – 200m where the groundwater is pumped at depths ranging from 45m plus.
The amount of water that can be pumped is determined by the type of pumps been used. The majority of the pumps used in the region are solar pumps capable of pumping up to 14 000 Litres/24hr, depending on the depth. The pumps located to the north and east of the Rooiberg fall within the ‘moderate’ zone for potential groundwater and these are limited to pumping at 2 500 – 3 000 Litres/hr. The Outspan test (East Rooiberg) concluded that a maximum of 7 200 Litres/hr could be pumped within this zone (GCS, 2001). In comparison with the boreholes to the south of the mountain, the pumps are located within the ‘good’ zone on the map and the yield is around 1 400 – 5 000 Litres/hr.
The two springs are located south of the Rooiberg and are situated right against the mountain itself. The springs originate out from the TMS where there is a change in slope. Both are near large lineaments and valleys higher up in the mountain that suggest that any water there could contribute to the seepage. Both yielded in and around 500 Litres/hr, however this amount drops during dry periods.
Conclusion
Through this study, a methodological approach of using remote sensing and GIS techniques to demarcate groundwater potential zones was established. The preparation of different thematic maps that included geology, landforms, lineaments, drainage density, slope and elevation was derived from remote sensing data and by conventional methods (topographic maps and field checks). By integrating the thematic maps using logically conditions and GIS techniques of that used in previous studies, a final demarcation map of the east catchment section of the Rooiberg was produced. Field checks and yield data from borehole and springs were used to verify the validity of the model.
The study area showed that north of the catchment, prospect zones are demarcated as very good to good and moderate constituting about 40% of the mapped area. About 50% of the study area falls under the prospects zones of poor to very poor, apart from about 10% just south of the catchment area. Valleys fill, pediplains, the bases of structural and residual hills are found to be favourable geomorphic units for groundwater demarcation. Geomorphic units of complex mounts, residual mounts and linear ridges are found to be poor indicators for groundwater potential. However, slope, elevation, geology and lineaments play key roles in location of springs and groundwater. Thus the current study has shown, to an extent, the means of using remote sensing and GIS to demarcate groundwater potential in the semi-arid environment of the Rooiberg.
Further studies
Although the above study has demonstrated the capabilities of using remote sensing and GIS techniques as a platform in demarcating groundwater, the study can be refined and changed to include other geohydrological sources and techniques. Other sources of data such as maps of landuse/land cover, soils and weathered/fracture thickness zones can be incorporated into the GIS model and therefore improve the accuracy of determining the groundwater potential. Again, filed checks were only carried out in the ‘good to moderate’ zones of groundwater potential and so further investigation to the groundwater yield in the other classes should be carried out in validating the GIS model.
Other reliable tests that can be used include geophysical surveys and Vertical Electrical Sounding (VES) that produce geoelectrical profiles of the subsurface lithology and to an extent even water quality (Murthy, 1999). Other factors that could be included as further studies are the nature and extent of groundwater recharge. Although the current study revolved around delineating groundwater zones, further investigation should be carried out into understating the nature of aquifers and groundwater resources of the Rooiberg
References
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Dept of Water Affairs (1986). Management of Water Resources of the Republic of South Africa.
Dept of Water Affairs & Forestry, 2002, A Groundwater Mapping Strategy for South Africa, Directorate Geohydrology publication, Pretoria, South Africa.
Dept of Water Affairs and Forestry (2004). Groundwater Use. Report 5E.
Dept of Water Affairs and Forestry (2005). Groundwater Quantification: Report 1D.
Dept of Water Affairs and Forestry (2005). Planning Potential Map: Report 2C.
Dept of Water Affairs and Forestry (2005). Recharge: Report 3aE.
Enslin, J.P., 1970. Die grondwaterpotensiaal van Suid-Afrika. Convention: Water for the future.
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Haupt, C.J. 2001. Water Resources Situation Assessment. Directorate of Water Resource Planning. Dept of Water Affairs and Forestry. Groundwater Resources of South Africa. Compiled by WSM Engineers.
Rosewarne, P.N. 2005. Groundwater Use and Availability in South Africa. Biennial Groundwater Conference, Pretoria.
Vegter, J.R. (1995). An explanation of a set of national groundwater maps. Water Research Commission Report No TT 74/95, Pretoria, South Africa.
Vegter JR, Seymour AJ and Simonic M (1995). Groundwater resources of the Republic of South Africa. A set of 7 maps. Water Research Commission and Dept of Water Affairs and Forestry.
Vegter, J.R. 2001. Groundwater Development in South Africa and an Introduction to the Hydrogeology of Groundwater Regions. Water Research Commission. Report No TT134/00.
In many areas of the Middle East, the proper functioning of the vital social mechanism depends on the stable supply of fresh water. In the case of Qatar, this supply is provided by the implementation of advanced desalination plants. However, despite the technological superiority of modern stations, they still remain subject to adverse external influence. This degree of vulnerability is entailed by the vital nature of desalination plants. As such, the oil spills in the Gulf remain one of the most serious hazards for Qatar’s freshwater supply in the 21st century. The contamination of water entails adverse consequences in several ways. First of all, it pollutes the Gulf itself, thus affecting the very source of such a vital resource. At the same time, oil-polluted water changes its physical properties, meaning that the essential elements of the equipment can be damaged. In order to mitigate the complications of oil spills, desalination plants devise various techniques of oil and water separation. This paper discusses the implementation of these approaches in desalination plants in Qatar.
Desalination in Qatar
The question of access to clean, potable water remains topical in the 21st century. Despite the unprecedented level of technological and social development, certain parts of the world continue to exhibit a serious shortage of stable freshwater supply. Qatar is one of the nations that retain such a need, as enabled by the geographical and climate conditions. According to Rahman and Zaidi (2018), the desalination campaign in Qatar has been developing since 1955. Evidently, across more than a half-century, the technology has evolved. Throughout this period, the desalination plant function has been associated with serious environmental concerns related to the increasing brine discharge (Rahman & Zaidi, 2018). However, the industry has currently been implementing reverse osmosis (RO) technology. One of the benefits of this approach consists of the advanced processing of brine, thus mitigating the environmental impact of the process (Darwish et al., 2012).
On the other hand, the expansion of the RO-based desalination industry entails a higher degree of vulnerability of the system itself. With a higher number of stations, potential oil spills in the Gulf and Arabian sea pose serious risks of malfunctioning through pollution. As a result, the industry’s decision-makers are prompted to work on efficient solutions that allow them to maintain a stable supply of freshwater in Qatar despite possible hazards.
Oil and Water Separation Techniques
One of the key objectives in terms of the anti-spill protection of desalination plants is to separate water from oil. In this regard, the removal of suspended solids and oil particles is the primary yet difficult objective (Judd et al., 2014). Saththasivam et al. (2016) discuss the existing variety of separation procedures that can be implemented in different settings, including desalination plants. First of all, some enterprises utilize the principle of a hydro cyclone, meaning that centrifugal forces move the water mass, allowing physics to remove from the core of the vortex due to its lower density. According to Saththasivam et al. (2016), this approach enables a “high throughput with very low retention time” (p. 674). However, it struggles to maintain a similar level of effectiveness in the case of heavy oil and stable emulsions. Modern scientists provide a chemical alternative, which consists of adding coagulants and flocculants to coalesce and aggregate the particles of oil in the water mass. Nevertheless, the costs of its implementation, namely the purchasing of chemical solutions and maintenance of pumps, are rather expensive. As a result, the use of chemical separation entails serious expenditures.
At the same time, there exist other approaches to oil removal from water that are based on physics. Gravity is the central force of this process, namely the specific gravity affecting immiscible fluids (Saththasivam et al., 2016). The gravity-based techniques enable the separation of large quantities of suspended oil in considerable water masses. The methodology of this approach relies on the differences in fluid density, which, under the right circumstances, enables an effective solution to the discussed issue. The equipment requirements are also not as significant as for the previously mentioned approaches. Consequently, the gravity settling in all its variety is a cost-effective method of water and oil separation.
Considering the continuous development of the industry and the remaining hazards, the field continues to work in constant pursuit of new techniques. As such, Saththasivam et al. (2016) discuss the specific details of the gas flotation method. According to the authors, this technique consists of using a floating mechanism that reduces the density of oil particles by concealing them within gas bubbles. The method effectively removes lighter and smaller particles that would otherwise evade the means of gravity. In addition, the systems are compact and easily transported in case of necessity. The disadvantages of the method consist of its reduced cost-effectiveness, which makes it less favorable for the industry of water desalination.
Oil and Water Separation Procedure
In spite of the existing variety of oil and water separation techniques, the area of water desalination continues to rely on well-tested, cost-effective methods. In Qatar, desalination facilities execute uninterrupted monitoring of the seawater intake in order to detect the first traces of oil contamination. Once such traces are observed, operators urgently reduce the speed and volume of the intake. Simultaneously, certified experts take seawater samples and conduct the analysis to determine the scale of contamination. Using the laboratory-obtained data, forecasts are made regarding the development of the situation. Subsequently, some intake gates are disabled, and the contaminated water is pushed toward them with special jets. This procedure serves to prevent the entry of oil-mixed water into the potable water tanks.
In order to ensure its proper execution, the staff members search for the signs of contamination in the treated water chambers. The specific smell of oil is one of the primary signs indicating that the integrity of potable water has been breached. Starting from the 0.50PPM contamination level, the advisory board may recommend disabling the desalination plant in its entirety. Simultaneously, mechanical skimmers are deployed on sight, gathering the droplets and gradually reducing the degree of contamination. Following these procedures, the staff uses oil booms and adsorbing pads to eradicate the remaining traces of the unwanted substance. All available resources remain in standby mode while the lab experts continue to run contamination tests. The operations of the plant can be resumed only once the multi-level analysis confirms the absence of oil or any risks of further contamination of potable water.
Conclusion
Ultimately, the vital status of desalination plants for the people of Qatar makes it necessary to create and maintain effective oil and water separation techniques. In this context, the decision-makers’ arsenal includes methods that are based on physical, chemical, or other principles. However, while the variety of separation techniques is considerable, the desalination industry of Qatar values cost-effectiveness above all. As a result, the gravity-based skimming procedures complemented by absorbing pads and oil booms remain at the core of the emergency protocol. Its proper implementation, combined with further rigorous research, can ensure a stable supply of potable fresh water to the residents of Qatar and other regions.
Judd, S., Qiblawey, H., Al-Marri, M., Clarkin, C., Watson, S., Ahmed, A. & Bach, S. (2014). The size and performance of offshore produced water oil-removal technologies for reinjection. Separation and Purification Technology, 134, 241–246.
Rahman, H., & Zaidi, S. J. (2018). Desalination in Qatar: Present status and future prospects. Civil Engineering Research Journal, 6(5), 1–7.
For a number of reasons, the consequence of sea water on concrete as a building material calls for extra interest. To begin with, buildings and other structures bordering or located offshore are open to the co-occurring processes of a number of physical and chemical wear and tear courses of action.
This presents an exceptional occasion to be aware of the intricacy of concrete resilience tribulations in practical applications. Secondly, seas constitute eighty percent of the earth’s surface and as a result, a huge number of constructions are accessible to marine water both in direct and indirect manners. While the structures along the coastline get in direct contact with the water, the ones that are inland also get contact with ocean water when strong winds carry the water inland in the form of spray.
When putting up of ports and docks, concrete is the material majorly used in wharfs, decks, retaining walls, and seawalls. Metropolitan overcrowding and contamination is a major problem that has led to the consideration(s) of putting up floating seaward platforms made mainly from concrete for placement of facilities like airfields, power plants, and throw away discarding installations (Threlfall, 4). Application of concrete seaward boring platforms and fuel storage reservoirs is also on an upward trend.
Concrete is a combination of rock or block fragments and sand aggregates with a binder substance, which is normally Portland cement. When muddled up with a correct proportion of water, the binder material hydrates resulting in tiny opaque gem webs encapsulating and bolting the collection into a stiff formation.
Archetypal concrete blends bear elevated resistance to compacting pressures, with typical values standing at approximately 28 Mega Pascal or 4000 psi. On the other hand, substantial tautness, for instance due to meandering will shatter the tiny firm pattern, ending up in fracturing and disjointing of the concrete. As a result of this, archetypal non-fortified concrete should be adequately propped up to put to a stop the advancement of tension.
If a component having elevated potency in tension is set in concrete, then the resultant substance, fortified concrete, stands firm against compaction forces, meandering forces and other direct tensile forces. A strengthened concrete segment where the concrete stands firm against compaction and reinforcement stands firm against tension can be cast into just about any form and dimension for the building sector (Portland Cement Association, 3).
Reinforced concrete refers to concrete within which fortification ingots, fortification meshes, laminates or twines have been set in to toughen the construction material under conditions of tautness. It was formulated by Joseph Monier in 1849. The reference Ferro Concrete means concrete that is strengthened using cast-iron or steel.
Other bits and pieces used to fortify concrete can be natural and amorphous fibers as well as composites in various kinds. Concrete as a construction material is tough in compression but frail in tension, as a result, incorporating fortification adds to its might in tension. What is more, the malfunction strain of concrete in tension is so little that the fortification has to cleave to the cracked segments together.
To end up with a strong, supple and long-lasting structure the fortification needs to have the following attributes; elevated strength, elevated tautness strain, superior tie to the concrete, thermal congenial combination, and hardiness in the concrete set up.
Fortified concrete can take in several forms of constructions and parts, together with slabs, partitions, beams, pillars, towers, foundations, among others. This form of concrete can be preformed or formed in place.
The way in which ocean water affects concrete was for the first time talked about in 1840. From that time the amount of information on the topic has gone up by a great deal, which is an implication of the significance of the topic.
For the most part, ocean water is fairly consistent in element composition, which is typified by the being there of approximately 3.5% soluble salts by weight. The concentrations of sodium and chloride ions are normally the utmost. They stand at 11,000 and 20,000 milligrams per liter, in that order. On the other hand, from the point of view of destructive activity to cement hydration products, adequate quantities of magnesium and sulfate are at hand.
They stand at 1400 and 2700 milligrams per liter, in that order. The pH (the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter) of ocean water ranges between 7.5 and 8.4. On the other hand, the mean value in balance with the atmospheric carbon dioxide stands at 8.2.
There are the particular environments like those in secluded bays and estuaries where pH measures of below 7.5 may be stumbled upon (Clear, 358). Such phenomena results from an elevated concentration of liquefied carbon dioxide, which in turn makes the ocean water more destructive to concrete made from Portland cement.
Concrete open to sea environment depreciates as a result of various activities. These include collective effects of chemical exploit of ocean water compounds on cement hydration products, base-cumulative spreading out in situations where rash conglomerations are existent, crystallizing action of salts inside concrete if one side of the construction is exposed to wetting and others to drying, ice activity in cold conditions, oxidization of set in steel in toughened or pre-stressed structural parts, and physical wearing down as a result of wave activity and floating matter.
Action on concrete as a result of any of the mentioned activities has a tendency to add to its permeability. This means the structure can be easily pervaded by sea water and this serves to make the material more and more predisposed to additional deterioration by the similar disparaging force and also other forms of destruction. For that reason, a network of interlinked chemical processes and physical forces are at hand to wear down concrete structures open to sea water.
The effect of corrosion on concrete constructions
From the point of view of chemical attack on hydrous Portland cement in unsupported concrete, in cases where base rash aggregates are lacking, sulfate and magnesium are the destructive elements in ocean water. In the case of well water, sulfate attack is referred to as rigorous when the concentration of sulfate ions is above 1500 milligrams per liter. In the same way, Portland cement mixture can wear down through swapping over of positively charged ions when ions of magnesium surpass 500 milligrams per liter.
Captivatingly, regardless of the lamentably elevated sulfate concentration of marine water, it is a widespread phenomenon that even when an elevated C3A Portland cement has been utilized and high volumes of ettringite are there as a consequence of sulfate attack on the cement mixture, the wear and tear of concrete is not set apart by spreading out. In its place, it more often than not takes the form of wearing away or loss of the solid elements from the volume (ACI Committee 222, 23).
It is strongly thought that ettringite spreading out is held back in settings where hydroxide (OH) ions have for all intents and purposes been substituted by chloride ions. While we are on the subject, this observation is in line with the proposition that an alkaline setting is crucial for the enlargement of ettringite by surface assimilation.
No matter the system by which the sulfate swelling linked with ettringite is held back in elevated C3A Portland cement concretes bare to marine water, the effect of chloride on the set up makes obvious the inaccuracy too many a time. This results in reproducing the performance of matter when, for the sake of plainness, the consequence of a single aspect on an occurrence is seen coming minus satisfactory regard to the other aspects existent. These effects may transform the outcome considerably.
It is worth noting that in accordance to the ACI Building Code 318-83, contact of sulfate with marine water is categorized as temperate, a case for which the use of ASTM Type II Portland cement is allowed.
The actuality that the existence of disjointed calcium hydroxide in concrete can result in wear and tear by a swap over effect concerning magnesium ions was identified as a early as 1818. This was from explorations on degeneration of lime-pozzolan concretes carried out by Vicat, without a doubt one of the originators of the expertise of modern cement and concrete (Clear and Hay, 67).
Depreciated structure members show evidence of a reduced amount of lime than the others when examined. What is lacking then has been liquefied and wiped off. Nature works to attain correct percentages, and to achieve them, rights the faults of force(s) which has fiddled with the measures. As a result, the upshot gets more discernible the more there is a move away from these correct fractions.
Quite a lot of high-tech assessments on the performance of constructions in sea settings bear out that Vicat’s analysis is by the same token suitable for Portland cement concrete. From long-standing researches of Portland cement mixtures and concretes bare to marine water, the verification of magnesium ion attack is well founded by the being there of white set downs of magnesium hydroxide and magnesium silicate hydrate.
In marine water, sufficiently-cured concretes having huge quantities of slag or pozzolan in cement normally go one better than orientation concrete having only Portland cement, to a certain extent since the former has not as much of disjointed calcium hydroxide following curing. The entailment of loss of lime by cement mixture, whether by magnesium ion attack or by carbon dioxide attack is illustrated in figure 1.
Figure 1 Loss strength in porous concrete as a result of lime leaching (adopted from I. Biczok, Concrete Corrosion and Concrete Protection, Chemical Publishing Company, Inc., New York, 1967, p.291
In view of the fact that marine water investigations rarely take account of the liquefied carbon dioxide substance, the prospect for loss of concrete volume through percolating away of calcium from hydrated cement mixture as a result of carbonaceous acid attack is in most times ignored.
In porous concrete the usual quantity of carbon dioxide existent in marine water is enough to putrefy the cementitious compounds in the long run. The existence of calcium silica-carbonate, calcium carbo-aluminate and calcium carbonate have been cited in cement mixtures drawn from depreciated concretes open to marine water for protracted times.
Permeability is the main solution to the durability of any concrete structure exposed to sea water or any other type of water (Song & Saraswathy). Injurious contacts of severe outcome involving components of hydrated Portland cement and marine water comes about in instances where the water is not put off from make a way into the interior of the concrete.
Archetypal foundations of not enough water protection are inadequately balanced concrete mixtures, lacking of adequately entrained air in instances where the construction is situated in a frosty type of weather, insufficient integration and curing, inadequate concrete cover on set in steel, poorly devised or put up joints, and mini fissures in consolidated concrete traceable to deficiency of power of stack circumstances and other aspects like thermal contraction, curing contraction, and base collection spreading out.
It is attention-grabbing to call to attention that engineers on the front position of concrete expertise are getting all the time more wide awake of the importance of permeability to resilience of concrete open to destructive waters. For instance, concrete stipulations for seaward constructions in Norway at present spell out the upper limit allowable permeability directly.
It is also worth noting that the nature and rigorousness of wear and tear may not necessarily be the same all the way through the structure. As illustrated in figure 2, with a concrete structure of cylindrical form, the segment that for all time remains higher than the high wave line will be more vulnerable to chill and ice wear and corrosion of set in steel. The segment that lays between high and low wave stripes will be susceptible to fracturing, not only as a consequence of chill action and steel oxidization but also from damp-dried up sequences. Substance attacks as a result of base-collection chemical reaction and marine water cement mixture contact will also be in operation here (Campbell & Folk).
Concrete that has been weakened by mini fracturing and chemical wear and tear will ultimately go to wrack and ruin by action and affect of sand, grate and frost. As a result, utmost wear and tear takes place in the tidal area. Then again, the completely sunken section of the construction will only be exposed to substance wear and tear by ocean water.
This is for the fact that it is not open to subfreezing temperatures and as a consequence there will be no dangers of ice smash up, and as a result of deficiency in oxygen only a slight corrosion can be expected. It comes into view that continuous chemical wear and tear of cement mixture by marine water from the outside to the core of the concrete tags on a common outline.
Figure 2 Diagrammatic representation of deterioration of concrete cylinder exposed to seawater.
The configuration of aragonite and bicarbonate by carbon dioxide deterrioration is normally restrained to the outside of concrete, the configuration of brucite by magnesium ion deterioration is located under the exterior of concrete, and proof of ettringite development in the inside illustrates that sulfate ions have the ability to make way even deeper.
Except if concrete is very pervious, no smash up comes about from chemical deterioration of marine water on cement mixture for the reason that the chemical reaction resulting compounds (aragonite, brucite, and ettringite) are insolvable and they have a propensity to reduce the permeability and bring to a close additional way in of marine water into the interior of the concrete. This form of defensive action would not be on hand under circumstances of active stacking and in the tidal area, where the chemical reaction resultant compounds are taken away by tide action as soon as they are established (LMI Draft Report to the DoD).
Oxidization of set in steel is, by and large, the main foundation of concrete corrosion in toughened and pre-stressed concrete constructions open to marine water, save for little-permeability concrete this does not occur to be the primary foundation of cracking. The corrosion pace on a structure counts on the cathode/anode area.
Oxidization and spreading out going along with the corrosion does not take place pending enough availability of oxygen at the exterior of the strengthening steel, that is, an augment in the cathode area. Results from several case studies seem to suggest that cracking oxidization exchanges in all probability tag along the course diagrammatically shown in Figure 3 below.
Figure 3 Diagrammatic representations of the cracking-corrosion-cracking cycles in concrete.
This does not take place as much as the permeability of steel-cement mixture bonding area remains low. Apertures and mini fissures by now are present in the bonding area, although their expansion by way of an array of events other than oxidization seems to be essential ahead of the setting for noteworthy corrosion of the set in steel. When the settings for noteworthy oxidization are set up, a more and more shooting up sequence of cracking oxidization commences, ultimately directing to full wear and tear of concrete.
Measurement tools for corrosion
The plan, putting into place and functioning of corrosion examination equipment requires know how in material science and electrical engineering. Thus, collection of data in this field has to be understood well. Oxidization probes are essential tools that cannot be serviced. They are planned and produced to go well with the particular construction. Essential aspects taken into consideration in the plan are the strengthening compactness and plaster, kind of form work, position of enduring examination apparatus, contact in the process and the period after construction.
There are the probe type tools and the M3 probe is the common one used. It is a multi-component feeler used to examine the pace of oxidization and state of toughened concrete constructions. It is designed to be set up at some stage in concrete erection and the probes are planned and produced to go well with the particular structure (Marusin, 58). A typical M3 probe consists of the following fundamentals: A carbon steel operational conductor, silver chloride/potassium chloride orientation conductor, stainless steel back up conductor and a thermostat hotness feeler.
Figure 4 Modified M3 probes all set for casting into a reinforced concrete structure.
The C4 probe is another multi-component feeler used to examine the corrosion pace and state of toughened concrete. It is modified for utilization in channel constructions but it is as well perfect for putting in place into any toughened concrete construction. The typical capacities the C4 probe gives touch on corrosion and hotness details for interiors and exteriors of curved constructions with respect to an orientation conductor at the same time as using an central hoop as an secondary conductor.
This probe is normally linked to the Rate of Corrosion in Concrete Concerto and gives the subsequent lay down of dimensions: corrosion prospective, oxidization pace, concrete resistivity, concrete temperature and concrete humidity.
Figure 4 C4 probe.
The M9 probe is another multifaceted component for use in aggressive settings like structures submerged in water where the capability to take readings at a range of depths giving timely caution of wear and tear is essential. Another example of such structures is nuclear storeroom plants.
Figure 5 M9 probe.
Another very important tool used in monitoring corrosion is the Concerto HTP engine that offers state-of-the-art monitoring for various purposes be it for field or research lab. Electrochemistry is applied in the instrument and the typical output from the tool is open-access information set up appropriate for straight transfer into catalog or worksheet functions. Adjustment software is made available to let users to fiddle with the dimension series for their specific application (ISO 7031).
Figure 6 Concerto RCC- NT Networked Monitoring Unit.
The Concerto RCC offers asset proprietors and sustainers with an incessant state account for the steel fortification and concrete mold in the face of compound wear and tear coercion from chloride dissemination, sulfate attack, permeation, thermal, and natural well water outcomes. When set up using DL or NT settings the dimensions permit straight correspondence with equipped and ecological bounds making it possible for performance developments to be set up and creating timely cautions of wear and tear with enough time to map and carry out corrective practices. The schemes are similar in temperament with upcoming cathodic safeguard application and can alter operation to bear out CP performance.
The RCC-DL undeviating data cataloguing set up is used to offer oxidization monitoring data for vital concrete constructions in both harmless and risky area settings where moveable components cannot be used and far-flung interactions are not necessary or achievable. At the same time as the RCC-DL set up is devised to function with the M3 and M9 probes, other set ups and probe kinds may be used.
The cost of corrosion on constructions and water front buildings
The cost of corrosion on concrete constructions exposed to marine water is enormously high and, thus, the focus on how the process takes place and how it can be slowed down or eliminated altogether. Following 21 years of use, the concrete stacks and tops of the supporting tower corners of the James River Bridge at Newport News, Virginia, called for a 1.4 million US Dollars patch up and substitution work.
This job entailed 70 percent of the total of 2500 stacks of the bridge. In the same way, 750 pre-formed concrete stacks driven back in 1932 in close proximity to Ocean City, New Jersey had to be patched up later in 1957 following 25 years of use (Nilson, 80).
A number of the stacks had been trimmed down from the initial 550 millimeters diameter to 300 millimeters. In both of these instances, the deprivation of matter was kinked with elevated levels of dissolved carbon dioxide existing in the marine water. Much later on, the 2002 findings of the research of the price tag of corrosion in the United States stood at the vale of three percent of the Gross National Product, GDP. This was an equivalent of 276 billion dollars.
Materials used for corrosion prevention
Majorly there are two kinds of up-and-coming expertise to take the edge off oxidization in strengthened concrete constructions. The first one comprises of exterior-applied oxidization inhibitors. These are substances that retard the process of oxidization. The other method involves an exterior-applied sacrificial cathodic safeguard outside layer. The oxidization inhibitor set up consists of three main components (US Patent 6627065).
These are; an ionic-anode form of inert piercing oxidization inhibitor, an unrefined steam part piercing oxidization inhibitor, and a rash silicone exterior safeguard means. The mutual utilization of these three oxidization-barring conceptualizations offers a long-lasting and multifunctional oxidization-barring setting. It also goes a long way in trimming down the water infiltration pace.
The sacrificial cathodic outside layer set up consists of an inert salt medium having zinc, aluminum, magnesium, and indium metals in the form of powder. This is applied to strengthened concrete on the outside along with titanium lattice stripes that are linked to the rebar to carry on cathodic electric current.
Tests carried out point out that oxidization rates of the rebar are trimmed down by a figure of 3.5 for the piercing oxidization inhibitor and 2.7 for the sacrificial cathodic safeguard outer layer. Water infiltration rates were also drastically went down. These outcomes show that appropriately picked and instituted piercing oxidization inhibitors or sacrificial cathodic outside layer set ups can be effectively utilized to lengthen the life of toughened concrete constructions by trimming down oxidization rates.
Other than the two ways of inhibiting corrosion in concrete discussed here, there also exist other methods of going about the exercise. Corrosion of set in reinforcing bars can be to a great extent trimmed down by setting crack-free concrete with little permeability and enough concrete plaster (Schiecl & Raupach, 56).
Reduced permeability concrete can be achieved by reducing the water to cementitious substances percentage of the concrete and use of materials like pozzolana and dross. These materials add to the concrete strength and trim down the corrosion rate even after it commences. Reinforcements can also be covered, for instance, using an epoxy resin, and use of sealants and casings on the concrete exterior. Sealants and casings, if applied, have to be from time to time reapplied.
The reinforcing steel can be set in at appropriate depths such that corrosion compounds from the outside do not get in touch. The water/cement relation can be kept lower than 0.4 and adequate detailing done to put off fracturing. Counteractive act for corroded concrete can consist of patch up the fractured part, and covering the exterior to bar additional entrance of corroding substances into the segment.
Construction designers have to mull over the amount of metal that is required to hold up the expected stress for a specific application. Due to the fact that they can make errors, the use of the construction can be altered, or the set up can be used wrongly, they normally are obligated to over design the construction by a factor of safety between 20 – 30%. A corrosion allowance is essential to maintain the construction secure if it does corrode.
Conclusion
Coastal regions and other areas bordering water bodies are very important to humanity and as a result have to be developed with various constructions like ports, harbors and hotels. The main construction material used is concrete. As a result, the way in which this material fairs on when subjected to water and marine conditions has to be fully understood so that structures set up in these areas can be put up to stand the tests of time.
This research has established that with proper set up and reinforcement, concrete constructions can last for long periods of time even when subjected to sea water. For that reason, the high costs associated with corrosion of concrete constructions can be significantly reduced with the proper procedures as a result of adequate knowledge on the matter.
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The ancient pump was designed to have a low-speed all-welded impeller with the suction bell trimmed so as to fit into the undersized pump. It also had a lightweight pump column that comprised of thin welded carbon steel plates. In order to provide resistance to erosion, Dent notes that the bearings were made of very hard carbides. It is also seen pump had a long unsupported shaft making its design and shape look very inferior. However, with time, modifications were made in a bid to correct the inefficiencies of the pump.
The Original Sump Design
The sump dimensions of the original pump were not in accordance with the Hydraulic Institute Standard recommendations. This was concluded to be because of the many vortices that were generated as a result of the hindrance in the flow of water due to the shape defect. The many defects in the sump design called for modifications so as to improve its performance as Dent suggests.
The Program to Correct The System
In a bid to correct the problem of the pump it is noted that a program was developed to review the entire circulating water system. The first correction was that of replacement with a titanium condenser that had a higher tube velocity alongside other pump modifications. Despite the many options such as the dual-speed pumps, variable pitch propellers and variable speed each of the options was weighed in terms of their pros and cons before settling on the best.
Pump Design Features
According to Dent, the new modifications resulted in different designs although there were similarities. For instance, the variable pump design closely resembled the single-speed pump with the only difference being the low-speed bearings of the latter. Nevertheless, the new pumps were made of cast aluminum bronze which was made into three sections bolted together. Their water supply was improved as bearings were of rubber and water lubricated.
The New Pump Design
The new pump had a modified sump which had a flat bottom under the suction bell, curtains, and comer filters all of which were to stabilize and improve the water flow.
The Impact on Condenser and Turbine
Although the modification improved the functioning of the pump, it can be seen that the excessive temperature reduction resulted in efficiency loss. Dent suggested that this shortcoming could be corrected by lowering the speed of the pump. However, Dent notes that before any corrective measure is taken, it is important to determine the type of fouling used.
