1.4.2Sources of water supply
Source of water supply should provide necessary amount of water taking into account perspective increasing of water consumption, uninterrupted water supplying, give water, which needs minimum expenses on its cleaning and its feeding to consumer. Besides, source power should be like that to selection of water to consumer needs doesn’t destroy complicated ecological system. There are surface and underground sources of water supply.
Surface sources of water (rivers, lakes, channels, storage reservoirs) are characterized by significant changes of water quality in different year periods. Water quality of rivers, lakes, reservoirs significantly depends on intensity of atmospheric precipitations, snow thawing, agricultural and production activity of a human in the water-intake zone.
River water has significant turbidity, especially in the period of spring floods and rains, rich by organic admixtures and contains great amount of microorganisms. At the same time content of salts and water stiffness, as a rule, is insignificant. Waters of lakes and reservoirs are characterized by the less turbidity, but can have significant colorations a result of alga and plankton development. The water quality of the surface sources doesn`t fulfill the demands of the state norms, that`s why it has to be purified and disinfected. Using the surface water they have to take into account the demands of sanitary-and-epidemiological services, the fishery conservation service, water transport and water conservation service.
Ground water by their position divides into unconfined groundwater and pressure middle water (deep-well). Natural rises of the ground water creates spring water. Infiltration water also label as ground water. It is surface water that is percolated through the bottom and bangs of the rivers and reservoirs and is drainages from the stratum by the intake.
Ground water (underground, deep-well, spring) in general don`t include insoluble, doesn`t has any color, excel by high level of transparence and usually can be used without purification for household water using. Comparing with surface water ground is more mineralized and, as a rule, have bigger iron contain.
Choosing source of water supply according to the sanitary reliability should be preferred (in the same sequence) usage of artesian, underground, under river bed rivers, and also surface river waters, lakes, water reservoirs. In all cases should be performed technical-economical calculations and bases.
Drawing 1.6. Scheme of underground waters lying.
Zone of pressure less waters
Zone of spouted water
Zone of pressure water: 1 – permeable to water layers; 2- interlayer artesian water; 3-underground water; 4- piezometric level of pressured water; 5 – ocks; 6 – level of free surface of pressured water; 7 water feeding field; 8 – sources area; 9,10 – wells of pressured and pressure less waters.
On all water supply sources and plumbing constructions of economical-drinking purpose for providing of sanitary-epidemiological reliability of systems of centralized and local water supply of settlements are installed zones of sanitary security according to the requirements according to the СНіП 2.04.02-84.
On all water supply sources and plumbing constructions of economical-drinking purpose for providing of sanitary-epidemiological reliability of systems of centralized and local water supply of settlements are installed zones of sanitary security according to the requirements according to the СНіП 2.04.02-84.
Zone of sanitary security of water-supply surface sources in the point of water-intake consists on 3 zones. First zone – is zone of strict regime. Source of water supply and plumbing constructions for intake, cleaning and reservation belong to it. Borders of the first zone of river sanitary security should be: up against of the river stream – not less than 200 m from water-intake, down on the stream – not less than 100 m from water-intake. For water reservoirs (lake, reservoirs) borders of the first zone should be not less than 100 m in all directions.
Territory of the first zone of the sanitary-security territory of the source of water supply, areas of plumbing constructions are enclosed, regulated and planted. Planning of this territory should provide drainage of the surface layer beyond zone’s territory. On the territory of the first zone forbidden all types of building (except plumbing), man dwelling, flow issuance, bathing, drinking and pasturing of cattle. Forbidden to use the territory for kitchen garden areas, washing of clothes, catch fish, and apply to plants chemical poisons, organic and mineral manures. This territory should be protected from coming of foreign persons.
Third and second zones of sanitary protection – are zones of limitation. On this territory doesn’t allow to let out flows and perform works which can led to the decreasing of quantity or worsening of quality of water in the water-supply sources. Sizes of the second zone are determined taking into account that water arriving from the border to the water-intake was not earlier than 5 days with average monthly water consumption 95-% provision. Down of the flow should be not less than 250 m. Third zone has the same parameters as the second one.
Ground sources of water-supply should also have 3 areas of the zone of sanitary protection. Borders of the first area of the sanitary protection zone (strict regime) are determined dependently on the degree of protection of water-bearing horizons from pollution from the earth surface and hydrogeological conditions on the certain distance from water-intake: for reliably protected horizons not less than 30 m; for not enough protected horizons – not less than 50m.
Borders of the second zone are determined taking into account that while microbes pollution of the water time of its movement from the border to the water-intake should be 100-400 days. Third zone takes into account chemical pollution of the water-supply source. Duration of chemical pollutions movement should be the same as duration of water-intake exploitation, but not less than 25 years.
During water-intake infiltrative and under-channel water borders of the sanitary-protection zone are determined, as for surface water-supply sources.
Limitations and prohibitions in zones of sanitary protection of underground water-supply sources are the same as in zones of sanitary protection of surface water-supply sources.