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Environmental Engineering

by Engineering KingsEngineering Kings
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Engineering Kings
Engineering Kings
UNIT-I PLANNING FOR WATER SUPPLY SYSTEM Public Water Supply System A public water system (PWS) is a system for the provision to the public of water for human consumption through pipes or other constructed conveyances, if such system has at least fifteen service connections or regularly serves at least twenty-five individuals. Planning Analysis is performed to identify water availability with sufficient quantity in desirable quality Design consists of collection, transportation, treatment and distribution For collection, source of water may be as near as possible to the town or city If water is not sufficient, then more sources are to be searched out Water requirement is ascertained on the basis of population forecast and per capita demand Quality of collected water should be as per requirements specified (Drinking or Industrial) Water treatment varies depending on source Flexible distribution system should be planned for future development which costs less with minimum effort for distribution Uninterrupted water supply during repairs and maintenance Objectives (i) To supply safe and wholesome water to consumers (ii) To supply water in adequate quantity (iii) To make water easily available for encouraging personal and household cleanliness. IMPORTANCE AND NECESSITY FOR PLANNED WATER SUPPLIES Next to the air, the other important requirement for human life to exists is water. Water is available in various forms such as rivers, lake, streams etc. The earliest civilizations organized on the banks of major river systems and required water for drinking, bathing, cooking etc. But with the advancement of civilization the utility of water enormously increased and now such a stage has come that without well organized public water supply scheme, it is impossible to run the present civic life and the develop the towns. The importance of water from only a quantity viewpoint was
recognized from the earliest days and the importance of quality come to be recognized gradually in the later days. The earliest recorded knowledge of water quality and its treatment are found in Sanskrit literature “Sushuri Sanhita” compiled about 2000 B.C. It deals with storage of drinking water in copper vessels, exposure to sunlight, filtering through charcoal, sand etc. The correlation between water quality and incidence of diseases was first established in 1849 by Dr. John snow when cholera appeared in London during the summer and 14,600 deaths were reported. But Dr. snow unable to convince the authorities and public with the evidence of available data. The water borne diseases like typhoid, dysentery, cholera etc the concept of water borne diseases was well accepted by 1900. Another striking example was reported from Uttarpradesh by W.H.O (World Health Organisation) in 1963, there the death rate by chorera decreased by 74.1%, Thyphoid fever by 63.6% , by dysentery 23.1% and diarria by 63.6%. All these were achieved by drinking water treatment. NEED FOR PROTECTED WATER SUPPLY Protected water supply means the supply of water that is treated to remove the impurities and made safe to public health. Water may be polluted by physical and bacterial agents. Water is also good carrier of disease causing germs. The causes of outbreak of epidemics are traced to pollute water and poor sanitation hospital are continued to be flooded with the sick due to ignorance about health continues to be profound. However during the last few decades, improvements in the public health protection by supplying safe water and sanitation to all the people in the developing countries. In 1977, united nations declare to launch a movement known as “HEALTH FOR ALL BY THE YEAR 2000 A.D.” India is also a signatory to that conference. The working group appointed by the planning commission while suggesting strategies for achieving the above goal emphasized that potable water from protected water supply should be made available to the entire population. Pure and whole some water is to be supplied to the community alone can bring down the morbidity rates At present, only 16 percent of towns in our country are equipped with water supply works serving about five percent of population of the whole of country. India has get to make serious efforts to make the treated water available to the most of its population so as to minimise the water borne diseases. Therefore protected water supply is a SIN QUO NON of public health of a community. The objectives of the community water supply system are 1. to provide whole some water to the consumers for drinking purpose. 2. to supply adequate quantity to meet at least the minimum needs of the individuals 3. to make adequate provisions for emergencies like fire fighting, festivals, meeting etc 4. to make provision for future demands due to increase in population, increase in standard of living, storage and conveyance 5. to prevent pollution of water at source, storage and conveyance
6. to maintain the treatment units and distribution system in good condition with adequate staff and materials 7. to design and maintain the system that is economical and reliable PLANNING AND EXECUTION OF MODERN WATER SUPPLY SCHEMES After british rule in our country, investments made in successive five year plans for planned development towards urban and Rural water supply and sanitation. Because of shortage of funds and some other reasons were responsible for slow growth of water supply facilities during the last five year plans. There are many central, state and International agencies coordinating and executing the urban and rural water supply schemes in the country 1. Central public health and environment organization under the ministry of works and housing formulates schemes and provide assistance to states planning and development. 2. National environment engineering research institute (NEERI) is a research institute of Govt. of India, conducts water quality surveys and suggests treatment processes and also provides design of treatment and distribution system 3. CSIR laboraties (council of scientific and industrial research) provide testing facilities for water quality maintenance. 4. Central ground water bound, Geological survey of India, national geographical research institute (NGRI) arte engaged afflicted by fluoride Iron, Manganese etc. 5. Technology missions were launched by Govt. of India in 1986 with submissions on control of flows 6. Bharat Heavy Electricals Limited is providing technology in such special processes like Reverse Electro-Dialysis. 7. Public Health Engineering Departments undertake execution of large schemes for water supply and sanitation. 8. State ground water department evaluates the quality and quantity of ground water all over the state. 9. Panchayat Raj Engineering department of state Govt. is the model agency for providing water supply and sanitation facilities in rural and urban panchayats. 10. A.P. State council of science and technology is engaged in assessing the status and quality of drinking water availability and requirements in selected areas. 11. Medium and major irrigation departments of Govt. undertake multipurpose schemes in the state with component of water supply along with Hydroelectric, irrigation, navigation, tourism and other services. 12. Educational institutions – many engineering colleges offer course in environmental engineering water supply and sanitary engineering at degree and
postgraduate levels. Polytechnics and vocational courses conduct courses in water supply engineering to train the technicians and engineers to the growing demand 13. International organizations like UNICEF (United Nations Health Organization) provide technical assistance and knowledge on water supply schemes working in specific problem areas. 14. There are many Non-Governmental organizations (N.G.O) like water development society, environmental protection societies operating in limited areas with donations and contributions by public and Govt. DESIGN PERIOD The complete water supply project includes huge and costly constructions such as dams, reservoirs, treatment works and network of distribution pipelines. These all works cannot be replaced easily or capacities increased conveniently for future expansions. While designing and constructing these works, they should have sufficient capacity to meet future demand of the town for number of years. The number of years for which the designs of the water works have been done is known as design period. Mostly water works are designed for design period of 22-30 years, which is fairly good period. Design Period It is the number of years in FUTURE for which the proposed facility would meet the demand of the community. OR This is the period into the FUTURE for which estimation is to be made. Factors affecting Design Period Selection of an appropriate design period for a particular facility / component of water supply system is very important and dependent upon following factors: 1.Length or Life of Structures. 2.Ease of Extension. 3.First Cost 4.Economy of Scale 5.Lead Time This time after completion of the project is called “design period”. It is expressed in years. During design period, the structures, equipment and components should be adequate to serve the requirements. As per normal procedure water works is designed for a period of 30 years. Influencing factors: i) Useful life of pipes, equipment and structures. ii) The anticipated rate of growth. If rate is more, design period will be less.

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