Presentation on theme: "EO 011.01 IDENTIFY POTABLE WATER SOURCES TP4. REFERENCES CFP 213 – CF Health Manual Public Health and Preventive Medicine, 14 th Edition, Maxcy-Roseneau-Last."— Presentation transcript:
EO IDENTIFY POTABLE WATER SOURCES TP4
REFERENCES CFP 213 – CF Health Manual Public Health and Preventive Medicine, 14 th Edition, Maxcy-Roseneau-Last
SOURCES OF WATER FIRST STAGE: The original source of all water is from the sea, by evaporation due to solar heat. Water vapour rises and condenses to form clouds, and on further cooling, the clouds precipitate their contents as rain, hail, sleet, or snow.
SOURCES OF WATER SECOND STAGE: All the precipitation falls back upon the earths surface, some of it in direct return to the seas, the remainder falling on land where it will: a.Follow the earths contours to form rivers and streams; b. Collect in hollows to form lakes and ponds; and c. Soak into the earths crust.
SOURCES OF WATER THIRD STAGE: The suns heat again evaporates water from the seas, lakes, ponds, and river surfaces and this water is again precipitated. Many rivers and streams are tributaries of the seas.
CYCLE OF WATER
SOURCES OF WATER Rain Water: In some areas, rain water is a major source of water supply. Such water is collected in cisterns, tanks, or reservoirs by run-off from the roofs of buildings and from mountain or upland areas.
SOURCES OF WATER Rain Water: This water is soft and well suited for laundry purposes. However, soft water will dissolve metals and, for this reason, rain water which has flowed through lead pipes or over lead or copper gutters may be dangerous to consumers.
SOURCES OF WATER Rain Water: Where rain water is in use, all cisterns, etc, should be individually checked for: a. Chemical contaminants; b. Mosquito larvae; c. Dead animals and birds; and d. Cross-connection with septic tanks or cesspools.
SOURCES OF WATER Surface Water: In the cycle of water it has been noted that when precipitation from the clouds falls on land, it will follow the contours to form rivers and streams and collect in hollows forming lakes and ponds.
SOURCES OF WATER Surface Water: Because all surface sources are, for the greater part, maintained by water which has flowed over the ground surface, through a catchment area populated by human and animal life, such sources are readily subject to contamination.
SOURCES OF WATER Aquifer: An underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, silt or clay) from which groundwater can be usefully extracted using a water well.
Aquifers may be considered as falling into two categories - confined and unconfined. A confined aquifer is one sandwiched between two impermeable rocks, and an unconfined aquifer is one where the water-table marks its upper limit. SOURCES OF WATER
SOURCES OF WATER Ground Water: Water which has percolated through the earths crust seeps down until it reaches an impermeable stratum above which it collects. The level of the water above the impermeable stratum is known as the ground water table.
SOURCES OF WATER Ground Water: All wells and springs are fed from ground water sources. This is a point to remember when planning septic tanks or other waste disposal systems which discharge or seep into the ground, for once a ground water source has become contaminated there are no practical means for its rehabilitation.
SOURCES OF WATER Oceans and Brackish Waters: These are unsuitable for water supply but, in conditions of dire necessity, fresh water can be obtained from them by one of several desalination processes.
The most appropriate method for desalination of seawater is thermal distillation. Distillation is widely used in oil- rich areas where water is extremely limited, such as the Middle East and the West Indies. SOURCES OF WATER
With brackish waters, where the salt content is less than 10% that of seawater, reverse osmosis or electrodialysis may be used. SOURCES OF WATER
WELL DESIGN Wells: There are two major classifications of wells: –Shallow –Deep.
WELL DESIGN Shallow wells: Trap ground water below its surface and, of course, above the first impermeable stratum. The level of the water in this type of well will depend upon the season and amount of precipitation, so that the yield is variable.
Shallow wells are readily subject to contamination either from surface water leaking through the top and sides, or from heavy demand depressing the surrounding water table thus entraining pollution from a distance. WELL DESIGN
If the surrounding soil is high in calcium (chalk or limestone), the water will be hard. Water from shallow wells must be disinfected before use. Such wells are seldom more than 30 feet in depth. The quantity of water will be limited. WELL DESIGN
Deep wells: Are sunk below the first impermeable stratum. This means that the supply come from below the first layer and is separated from it. Should water from above the first layer reach the deep well supply it will have, to some extent, been filtered through the interstices of the first layer.
Deep wells are also subject to contamination from remote sources if the geological formation is fissured. Deep well water may be hard but in general, will be of better quality than that from a shallow well. WELL DESIGN
The quantity of water available will be greater than from shallow wells, but may become limited by heavy demand. WELL DESIGN
In both shallow and deep wells the well top and casing should be of impervious construction down to the water level. WELL DESIGN
Artesian wells: Are deep wells in which the water is under natural pressure and which rises under its own head to the surface. The quantity of water will be copious.
WELL DESIGN Springs: Occur where an impervious stratum emerges on to the surface, usually on sloping ground, below a water table. Springs may be polluted in the same way as wells, but may occasionally be of high yield.
WELL DESIGN Dug Well: Excavated by hand or mechanical equipment; may be feet in diameter and 15 – 35 feet deep; not usually dependable source of water and susceptible to contamination when subjected to heavy rains (runoff)
Bored Well: Constructed with hand or machine-driven auger; vary in diameter from 2 – 30 inches and 25 – 60 feet deep; casing of concrete, clay, metal or plastic pipe is necessary to prevent soil formation from caving into the well WELL DESIGN
WELL DESIGN Driven and Jetted Well: Consist of a well point with a screen attached, or a screen with the bottom open, which is driven or jetted into a water-bearing formation found at comparatively shallow depth
WELL DESIGN Drilled Well: Generally superior to all other types of wells; less likely to become contaminated and a more dependable source of water. It is usually 4 – 12 inches in diameter and may reach depths of 750 – 1000 feet
WELL DESIGN Well Development: All well drill methods cause smearing and compaction or cementing of clay, mud and fine material on the bore hole wall and in the crevices of the formations penetrated; reduces sidewall flow of water into the well and thus yield;
various methods used to remove these materials; development continued until discharge is practically clear of sand; final step is testing for yield followed by disinfection WELL DESIGN
Grouting: Common cause of contaminated wells through rock, clay, or hardpan is failure to properly seal the annular space around the well casing; proper seal required to prevent water movement between aquifers.
To protect aquifers, and prevent entry of contaminated surface or near-surface water; proper cement grouting between drill hole and well casing (a ring-like structure known as the annulus) can prevent this. WELL DESIGN
WELL CONTAMINATION Bacteriological Contamination: Treat or boil water used for drinking or culinary purposes
WELL CONTAMINATION Chemical Contamination: Boiling will not remove chemicals except volatiles; treatment (filtration) may remove some
WELL CONTAMINATION Action: Abandonment of well (if practical) and connection to municipal water supply; determine cause of contamination and rectify; drill new well
WELL CONTAMINATION Probable Causes of Bacteriological Contamination: –Lack of or improper disinfection following repair or construction –Failure to seal the annulus (annular space around the casing)
–Failure to provide tight, sanitary seal where pump lines pass through casing –Wastewater pollution through polluted strata or a fissured or channelled formation Note! Chemical contamination usually means the aquifer has been polluted. WELL CONTAMINATION
Sewage Disposal Systems is suspected of Contamination: Use of a dye such as water-soluble sodium or potassium fluorescein (orange dye) or ordinary salt can be used as a tracer; solution flushed into suspected source may appear in well water within hrs; may be detected by sight, taste or analysis.
WELL CONTAMINATION Underground seal is suspected of contamination: Use a dye or salt solution or even plain water can be poured around the casing. The seal might also be excavated for inspection.
WELL CONTAMINATION The side of the casing is suspected of contamination: When holes in the side of the casing, channels along the length of the casing leading to the well source, crevices or channels connecting surface pollution with the water-bearing stratum, or the annulus. Use a dye or salt solution or even plain water can be used to trace the pollution.
WELL CONTAMINATION Well sidewalls not watertight: If a dug well shoes evidence of contamination, the well sidewalls may be found to consist of stone or brick lining which is far from being watertight. In such cases the upper 6 to 10 ft should be removed and replaced with a poured concrete lining and platform.
WELL CONTAMINATION Chemical contamination is suspected: Chemical contamination of a well and the groundwater aquifer can result from spills, leaking gasoline and oil tanks or improper disposal of chemical wastes such as by dumping on the ground in landfills, lagooning (artificial pool to accommodate overspill) or similar methods.
WELL CONTAMINATION Once a stratum is contaminated, it is very difficult to prevent future pollution of the well unless all water from such a stratum is effectively sealed off.
Moving the offending sewage disposal system to a safe distance or replacing a leaking oil or gasoline tank is possible but evidence of the pollution may persist for some time. WELL CONTAMINATION
Unless all the sources of pollution can be found and removed, it is recommended that the well be abandoned and filled with neat cement grout, puddled clay or concrete to prevent the pollution from travelling to other aquifers or wells.
EO FIELD WATER SUPPLY TP 7
REFERENCE CFP CF Health Manual
FIELD WATER SUPPLY WATER SUPPLY IN THE FIELD: In the field, water point operation is a responsibility of the Engineer Field Squadron. The selection of a water point will always be subject to the tactical situation.
This may prevent the use of one ideal water source in favour of another which is, possibly, less desirable from the hygienic standpoint, but better suited to the operational plan. FIELD WATER SUPPLY
Water point selection: The selection of water points is decided by the force commander, usually represented by a staff officer in consultation with an engineer officer and a CFHS officer.
This enables a decision to be made which includes the tactical engineering, and medical aspects of the situation. Water points are sited wherever water exists in sufficient quantity to meet the actual, or anticipated demand. FIELD WATER SUPPLY
Water point selection: They should: –be accessible by road and as close as possible to the unit areas to be served; –provide sufficient space for vehicles to turn around;
–be provided with equipment of adequate capacity to rapidly filter, disinfect, and fill tanks and containers; and –be provided, where necessary, with sedimentation tanks for preliminary settlement of suspended matter. FIELD WATER SUPPLY
Types of Water Points: A mobile water treatment unit set up at an available source provides a water point which is limited only by the yield from the source and the capacity of the treatment unit.
The operation of these units is, as noted, an engineering responsibility the object of which is to produce drinking water which has been clarified, filtered, and disinfected to the satisfaction of the CFMS. FIELD WATER SUPPLY
Types of Water Points: Municipal water works systems may be utilized as water points on active service, provided that such water satisfies, or can be made to satisfy, medical requirements Any industrial or privately owned water source may be utilized as a water point provided that medical requirements can be met.
FIELD WATER SUPPLY Types of Water Points: A filled tank vehicle may furnish the water point at its destination. Bulk Milk trucks, for example, can be easily converted to water carrying vehicles, however Gasoline tank trucks must not be used for this purpose. At all times, it must be assured that the tanks have been cleaned and disinfected prior to use, and that the water conveyed has been disinfected.
FIELD WATER SUPPLY Number of Water Points: The number of water points to be provided will depend on: a. The availability of water sources such as lakes, rivers, ponds, streams, wells, and springs; b. The tactical situation as previously noted; c. The scale of water issue as advised by the medical service; d. The strength of the force to be supplied; e. The disposition of units in the area; f. The capacity of delivery vehicles and other equipment available; and g. The farthest distance to which water must be delivered.
FIELD WATER SUPPLY Civilian Water Supplies: The respective responsibilities commanders, the medical and engineering services with regard to water supplies are not lessened where supplies are obtained from a treated municipal water supply system under contract between the municipality as the supplier and DND as the consumer.
Samples taken from the municipal supply must have shown, and continue to show, satisfactory water quality on bacteriological examination. FIELD WATER SUPPLY
EO PROTECTION OF SOURCES TP 8
REFERENCE CFP CF Health Manual
PROTECTION OF SOURCES General Principles: In any program of water sanitation: First consideration is the protection from pollution of available sources of water supply;
PROTECTION OF SOURCES Second consideration, and almost equally important, principle is to protect unsuitable sources from unauthorized use by troops, or by civilians for whose care troops may be temporarily responsible.
PROTECTION OF SOURCES Catchment Areas: Usually a civilian function which includes restriction of the land area involved for building development or use by campers; fencing of certain portions of the area to exclude animals; and patrolling to prevent unauthorized access and swimming.
PROTECTION OF SOURCES Purification: The process of water treatment, including filtration and disinfection, is of paramount basic importance as a protective measure against disease.
PROTECTION OF SOURCES Surface Waters: Where lakes or ponds are used as sources of water supply, the water should be taken from the deepest part, where possible.
When using rivers or streams, a point upstream from habitation or other source of pollution should be selected. In either case, strict attention must be given to disinfection of the supply. PROTECTION OF SOURCES
Protection of Wells: Pollution of wells occurs from two sources: underground and surface and both must be guarded against.
PROTECTION OF SOURCES Protection of Wells: Sources of underground pollution include drainage from outhouses, livestock operations, etc. Wells should not be located in the path of drainage from these like sources of contamination.
Setback distances cannot be accurately defined but a generally accepted minimum distance is 50 feet, preferably 100 feet between a well and a known source of contamination. This distance factor, however, is not in itself a guarantee of safety. PROTECTION OF SOURCES
Protection of Wells: Surface control of pollution is largely a function of proper design such as sufficient clearance above grade of the well cap and adequate grading of soil around the well cap to allow surface water from rainfall to drain away and not pool.
EO CISTERNS TP 9
REFERENCE CFP CF Health Manual
PROTECTION OF SOURCES Cisterns: Rain water cisterns are a source of supply in rural homes in Canada, and in those regions where other natural supplies do not exist.
Cisterns are usually fed by roof run-off. In general, rain water collected from a tiled or slated roof will be safe to use after disinfection, provided NBC contamination is absent. PROTECTION OF SOURCES
EO CROSS-DONNECTION TP 10
REFERENCE CFP CF Health Manual
PROTECTION OF SOURCES Cross-connection: A cross-connection is any physical connection or arrangement between two otherwise separate piping systems, one of which contains potable water and the other unsafe water or other liquid, steam, or gas causing a flow from one system to the other.
EO BACK-SIPHONAGE TP 11
REFERENCE CFP CF Health Manual
PROTECTION OF SOURCES Back-siphonage: Again, heavy demand upon a water service beyond its capacity, will result in a drop in pressure to an extent where the water instead of flowing towards a fixture begins to flow away from it.
PROTECTION OF SOURCES Back-siphonage: This is call a negative pressure. Negative pressure sets up a suction in the fixture and can result in used, contaminated, or polluted water from the fixture, eg; a toilet or urinal, flowing back into the water service pipe.
This is know as a back-siphonage. It is a situation which can arise when an accommodation is occupied by more persons than it was designed for.
It is likely to be a health hazard when a normal community population is increased by refugees from war or natural disaster. PROTECTION OF SOURCES