Water Testing in Emergencies

Waterborne infectious diseases, in most emergencies, include diarrhoea, typhoid, cholera, dysentery and infectious hepatitis due to transmission of faecal pathogens, due to inadequate sanitation, hygiene and protection of water sources However, some disasters, including those involving damage to chemical and nuclear industrial installations, or involving volcanic activity, may create acute problems from chemical or radiological water pollution.

Whatever the source and type of contamination, decisions on acceptable water quality in emergencies involve balancing short- and long-term risks and benefits to health. At the same time, ensuring access to sufficient quantities of water is vital for health protection.

Many chemicals in drinking-water are of concern only after extended periods of exposure. Thus, it is advisable to supply water in an emergency, even if it significantly exceeds WHO guidelines for some chemical parameters, if the water can be treated to kill pathogens and then supplied rapidly to the affected population. This will reduce the risk of outbreaks of water-borne and water-washed disease. When water sources are likely to be used for long periods, chemical and radiological contaminants of more chronic health importance should be given greater attention. In some situations, this may entail adding treatment processes, or seeking alternative sources.

Bacteriological testing

The principle of bacteriological testing is to identify a “faecal indicator” organism that is always excreted by warm-blooded animals, both healthy and unhealthy, and to take the degree of its presence as an indication of the degree of faecal contamination. Bacteria from the thermotolerant (faecal) coliform group are nearly always present in faeces, so their presence in water is a strong indication of faecal contamination. Typically, most thermotolerant coliforms are of the species Escherichia coli, which is always derived from faeces. The presence of any bacteria from the total coliform group is sometimes tested for, particularly as an indication of the effectiveness of a water-treatment system. Many members of the total coliform group are free-living and their presence does not depend on the presence of faecal contamination, but it can indicate that a treatment process has not removed or killed all bacteria. Other faecal indicator bacteria include faecal streptococci/ intestinal enterococci. Field kits for bacteriological testing usually employ the membrane-filtration technique, where a measured volume of water is filtered through a membrane, which retains the bacteria on its surface. The membrane is then incubated on a suitable medium, using a battery-powered incubator, for 18 hours. During this time, the thermotolerant coliform bacteria reproduce and form colonies. The number of colonies formed provides an index of the degree of faecal contamination in the original sample. This test is generally easy to perform. However, high turbidity caused by clay, algae, etc. (which may be suspended in large quantities after storms and floods) can interfere with the test, but as small volumes are often analysed in these circumstances, this may not be a significant problem. The multiple-tube method is an alternative to membrane-filtration. Quantities of the water to be tested are added to tubes containing a suitable liquid culture medium and incubated, typically for at least 24 hours. The bacteria present in the water reproduce, and the most probable number of bacteria present is determined statistically from the number of tubes giving a positive reaction (colour change and/or gas production). This test can accommodate even turbid samples, containing sewage, sewage sludge, or mud and soil particles.

Bacteriological guidelines

Conventional bacteriological standards may be difficult to achieve in the immediate post-disaster period. The WHO guideline of zero E. coli per 100 ml of water should be the goal (World Health Organization, 1993a) and should be achievable even in emergencies, provided that chemical disinfection is employed. Recognizing that achieving the guideline standards may be difficult in some emergency situations, it is practical to classify water quality results according to the degree of health concern (Lloyd & Helmer, 1991; Delmas & Courvallet, 1994). For example:

— zero E. coli/100ml: guideline compliant;

— 1–10 E. coli/100ml: tolerable;

— 10–100 E. coli/100ml: requires treatment;

— greater than 100 E. coli/100ml: unsuitable for consumption without proper treatment.

An indication of a certain level of a faecal indicator bacteria alone is not a reliable guide to biological water quality. Some faecal pathogens, including many viruses and protozoa, may be more resistant to treatment (such as by chlorine) than the indicator bacteria. More generally, if a sanitary survey suggests the likelihood of faecal contamination, then even a very low level of contamination measured by bacteriological analysis may be considered to be a risk, especially during an outbreak of a disease like cholera that may be water-borne. The parameters most commonly measured to assess microbial safety are: E. coli (thermotolerant coliforms); residual chlorine; pH; and turbidity.

Residual chlorine

Chlorine content should be tested in the field with a colour comparator, generally used in the range of 0.2–1 mg/l of water. Taste does not give a reliable indication of chlorine concentration.

pH

It is necessary to know the pH of water because more alkaline water requires a longer contact time or a higher free residual chlorine level at the end of the contact time for adequate disinfection (0.4–0.5 mg/l at pH 6–8, rising to 0.6mg/litre at pH 8–9, and may be ineffective above pH 9).

Turbidity

Turbidity, or cloudiness, is measured to determine what type and level of treatment is needed. It can be carried out with a simple turbidity tube that allows a direct reading in turbidity units (NTUs). Turbidity adversely affects the efficiency of disinfection

Chemical and radiological guidelines

Water from sources that are considered to have a significant risk of chemical or radiological contamination should be avoided, even as a temporary measure. In the long term, achieving WHO guidelines should be the aim of emergency water-supply programmes based on the progressive improvement of water quality.

Testing kits and laboratories

Portable testing kits allow the determination in the field of water pH (acidity/alkalinity), free residual chlorine, faecal coliform bacteria count, turbidity and filterability. When large numbers of water samples need testing, or a broad range of parameters is of interest, laboratory analysis is usually most appropriate. If laboratories at watertreatment works, environmental health offices and universities no longer function because of the disaster then a temporary laboratory may need to be set up. When samples are transported to laboratories, handling is important. Poor handling may lead to meaningless or misleading results. Workers should be trained in the correct procedures for collecting, labeling, packing and transporting samples, and for supplying supporting information from the sanitary survey to help interpret laboratory results.

Earthquake Impact on Water Systems

To determine earthquake hazards, information about earthquake sources and mean values of their attenuation, displacement rates, uncertainty of these parameters and local design standards are essential and professional personnel having expertise in particular techniques involved in analysis of seismic risk along with technical persons of water supply authority are required. They should have knowledge about system components and their importance in water supply system.

In some region earthquake may sometimes associated with volcanic activity. A violent volcanic activity may generate eruptions which may even block water courses or produce diversions.

The eruption materials like lava flows, ash and gases may severely damage exposed structures. Avalanches and landslides may even produce total collapse of them. Metal structures like valves & tanks and treatment plants may become damaged while acid rain and ashfall.

Severity of earthquake:

Depending on energy released (i.e. magnitude), an earthquake can produce:

• Settlement of ground surface
• Fault propagation in rocks
• Landslides
• Caves-ins
• Mudslides

Vibration in saturated cohesionless soil can produce liquefaction which in combination with seismic waves can result severe damage and even total destruction of water supply system components.

Severity, in other word degree of damage depends usually on:

• Magnitude of earthquake, depth is also important as it defines extent of tremor.

• Behavior of soil as site amplification may enhance earthquake damage. Say a landslide near water system components or failure of dam destructing or reducing reservoir capacity; contamination of existing or treated water may also occur.

2) Elevated tanks.

Elevated tanks of average or large size are usually constructed from steel or reinforced concrete.

a) Tanks supported by steel frames with adequate diagonal bracing perform well in earthquakes. Their most vulnerable point is where pipes (which form the supporting structure) penetrate the ground. However, different kinds of design, construction, and maintenance of steel tanks, combined with diverse earthquake magnitude and response of the supporting soil, can produce:

• Light damage, such as shear of the diagonal supports, which can be repaired or replaced quickly;

• Damage in the supporting structure and/or in the storage tank can vary from minor to very serious. The most severe damage will likely occur in the connection between the supporting structure and the pipes;

• Collapse of the structure.

b) Concrete tanks can be affected by earthquakes in the following ways:

• Loss of exterior stucco. This is easily repaired although scaffolding may be required;

• Damage to pipes entering or leaving the tank or to superimposed elements such as access ladders. These elements do not compromise the structure and their repairs can range from slightly to moderately difficult;

• Cracks in the supporting structure or storage tank which can occur in the areas of overlap of an excessive number of steel reinforcements, at points where the pipes cross the concrete walls, in the connection between the storage tank and support structure, or in the foundation of the support structure;

• Toppling or leaning of the structure, or foundation failure. This is usually of serious significance;

• Collapse of the structure.

According to the UNDRO study (1982), the survival index of elevated reinforced concrete tanks is less than that of steel tanks, and the precautions for their construction are less clearly defined. Reinforced concrete structures can hide more damage than steel structures, so any damage that exceeds superficial loss of stucco should be examined by a specialist. What appear to be simple cracks can cause major problems when a subsequent earthquake occurs.

c) Small elevated tanks.

Small water storage tanks used for individual dwellings, small groups of houses, schools, small industry, etc., are built of a large variety of materials. The support structure may be built of wood, structural steel, reinforced concrete, etc. The tank may be of corrugated or smooth iron, asbestos cement, fiberglass, reinforced concrete, etc.

• Corrugated iron tanks collapse frequently during earthquakes, but experience shows that this is more often due to poor maintenance than to instability.

• Damage in the support structure and/or in the tank may require simple repairs, or if the structure collapses, require tank replacement. It may be possible to salvage part of the material from wooden and metal structures (except where there is corrosion).

iii) Dams and Reservoirs:

Only dams and reservoirs for drinking water supplies are addressed here. Seismic activity in reservoirs can cause large waves that will overtop the dam. Cave-ins or landslides falling into the reservoir can generate damaging “internal” tidal waves. Floods resulting from the rupture of a dam can have very serious and unpredictable consequences for populations located downstream from the dam.

a) Rock-fill dams are more flexible than those of concrete and more resistant than earth dams. However, the clay or concrete used to make these dams water-tight can crack in an earthquake, resulting in leaks. Possible damage would include:

• Small, medium, or large cracks or leaks;

• Collapse of reservoir embankments;

• Total collapse of the dam.

b) In earth dams, earthquakes cause failure of foundations, cracks in the core, landslides in the dams, waves in the reservoir causing landslides in the dykes, and overtopping or collapse of the core wall. Other damages include:

• Small leaks which should be immediately repaired to avoid the increase of erosion;

• Accumulation of soil because of landslides, which may need to be dredged;

• Collapse of the dam.

c) Concrete dams can crack or the foundations can fail. As in all dams, there is the danger that waves will overtop the dam. Possible damage could include:

• Cracks or small leaks that should be repaired immediately;

• Cracks that would require the reservoir to be emptied for repair (implying loss of stored water);

• Accumulation of soil due to slides;

• Collapse of the dam.

B) Earthquake Damage to Underground or Buried Works:

Underground works include:

a) piping and conduits of drinking water, sewage, and storm water; chambers, valves and domestic installations;

b) Underground water intakes such as wells, drains, and galleries.

These works differ significantly from surface works since, for the most part, damage will not be visible, making actual damage assessment much slower and more labor intensive. For example, within 15 days of the Mexico City e a r t h q u a k e, the major damage to the drinking water mains had been repaired, but months were required to complete smaller repairs, and it was much more complex and time-consuming to repair the sewage and storm drain networks.

The earthquake exerts inertial force on above-ground structures, but buried structures such as pipes and rigid connections can be damaged as the earth undergoes deformation. Less damage can be expected in relatively more flexible pipelines (PVC or steel, for example) compared with rigid pipes such as compressed mortar, concrete, cast iron, and asbestos cement, especially if they have rigid joints.

i) Influence of Soil Type on Damage.

I n embankments built of infill, or in soft soils, earthquakes can break buried pipes. Failures also occur in pipelines located in areas where there is a change of soil type, as in changes in density of natural fill. The liquefaction of soil is one of the most damaging effects of the earthquakes since it reduces foundation support. A large part of damage to pipes in alluvial terrain or water saturated sand occurs because of liquefaction. For example, in Japan, in an area of saturated sands, earthquake vibrations practically converted the soil into a liquid in which the pipes and chambers “floated”, causing major damage to the installations. Large diameter pipes placed at a shallow level suffer more damage than those of smaller diameter, since they have less resistance to “Rayleigh waves” which are dispersed over the earth’s surface in a similar, though less obvious, way as waves of water. Another area of potential damage is in the proximity of pipes to buildings that collapse. The rupture of pipes that enter or leave buildings can wash out public network pipelines to which they are connected.

ii) Seismic Risk Maps Showing Ground Quality.

Given the difficulty of locating damage in existing pipelines, a review of seismic risk maps of the areas affected will show the most vulnerable areas, for example:

• Areas with deep layers of soft soils, sands and sedimentary gravel, swamps and infilled areas (i.e., subsoils that do not absorb seismic vibrations as do hard rock);

• Areas with layers of loose sand that are saturated with water and other non-cohesive soil strata in which the soil can soften;

• Faults in the rock strata (pipelines that cross these faults can suffer damage).

iii) Locating Damage in Pipes:

a) Damage to drinking water pipelines. Damage commonly produces water seepage in areas close to the breaks in the pipes or connections. To determine the magnitude and extent of damage and to make urgent repairs, it is necessary to excavate the lines to find the broken pipe. However, where there are highly permeable soils or low water pressure, it is possible that breaks will be detected only after service is restored. Some indications of this kind of damage are as follows:

1) New leaks evidenced by increased pressure in the network after the breaks initially discovered are repaired;

2) Areas of a city or town that continue without water service or have lower pressure after repairs have been made. This might be due to damage in pipes feeding these zones, which should be identified and repaired.

3) Detecting leaks can be very time-consuming, especially if the necessary equipment and expertise are not locally available. It can be difficult to determine which leaks were caused by the earthquake and which existed before the event.

4) Flow meters installed at appropriate points in the mains of the network can detect the existence of leaks.

b) Damage to Sewage Pipes.

Surface seepage of waste water can be indicative of an area of damage. However, since these are usually open channel flow pipelines, without pressure, there may be fewer visible leaks than in drinking water pipes where pressure can facilitate detection of damage. Manholes can facilitate the visual assessment in successive chambers to locate sections with leaks (by comparing the levels of waste water in neighboring chambers). Breaks in the pipes, if they did not exist before, can be a product of the earthquake. Where the drinking water supply is interrupted as a result of the disaster, there will be no return waste water. Normalization of the drinking water supply must occur before final inspection of the waste water system can take place.

c) Storm-water Drainage System

If a disaster occurs during the rainy season, the review of this system would be similar to that discussed for the sewerage system. However, if it occurs in the dry season, a visual inspection of damage could be carried out by following waste water channels and major sewer mains, accessible sewer mains, if they exist, and by inspection of neighboring reaches from adjacent manholes.

iv) Risk of Contamination of the Drinking Water System.

If pipes from the drinking water and waste water systems break simultaneously, the waste water will penetrate the drinking water system (especially if there is a considerable volume of waste water spread on the ground). This occurs because pipes for drinking and waste water are usually built parallel to each other, along the same streets. In certain cases there is ground water that covers the drinking water and sewerage networks. Ground water contaminated by breaks in the sewage system can infiltrate the drinking water system through broken joints. This is likely to occur if there is negative pressure as a result of breaks in the system or because of rationed drinking water.

C) Effects of Earthquakes on Ground Water Collecting Works.

In areas where water is taken from deep wells or filter galleries, the earthquake can cause the ground water to flow into newly opened fissures resulting in a decrease, and even the exhaustion of the flow obtained from these intakes. Contamination is also a hazard when cracks or faults connect surface water or water from latrines with ground water, rendering intakes useless.

1) Damage to Medium, Deep, or Large Diameter Wells:

Given the variety of wells that exist, various types of damage can occur, including:

• Settling of soil around the well, resulting in slight to severe damage;

• Collapse and total loss of the well (for example, as a result of a fault that traverses the well and causes its collapse, or because of cave-ins that cover it);

• Slight to severe damage in the pumping mechanism.

2) Damage to Filter Galleries or Drains:

In underground galleries or drains, the earthquake can cause various types of damage, including:

• Cracks in the walls, pipes or beams that form the drain or filter gallery. Cracks may be relatively easy to repair (if the filter gallery is accessible) or require interior reinforcements or replacement of the facing of the drain.

• Partial cave-in of part of the filter galley, drain, or manholes;

• Total collapse of the filter gallery or drain;

• Damage to pumping equipment (if it exists).

D) Contamination of Drinking Water Sources.

The risk of ground water contamination was mentioned in the previous section, but a more common hazard is the contamination of surface sources of drinking water. This may occur because of the presence of animal carcasses, or the discharge of petroleum, industrial or toxic wastes into bodies of water, posing one of the greatest large-scale hazards to health in the event of an earthquake. In such cases, it will be necessary to immediately identify alternative sources, and construct (or rehabilitate) intakes and distribution systems for drinking water.

To estimate damage as a result of seismic action, special attention should be given to the stability of foundation soils, including the points described above. The typing of components should consider the interaction with other components that could modify their dynamic response during ground shaking.

Table shown below provide a synthesis of the expected performance of pipes during intense earthquakes.

The expected effects of earthquakes on drinking water and sewerage systems can be summarized as follows:

• Total or partial destruction of intakes, conveyance structures, treatment facilities, storage, and distribution;

• Breaks in delivery and distribution pipes and damage in connections between pipes or with tanks, resulting in a loss of water;

• Interruption of electric power, communications, and access routes;

• Change in water quality because of landslides;

• Variation (decrease) in the flow of underground or surface collector works;

• Change in the site of water outlets in springs;

• Damage from interior coastal flooding caused by tsunamis.

Emergency Water Treatment Processes

Emergency or short-term treatment of drinking water may be necessary due to natural disasters, accidents or other situations caused by humans. In these situations, water can be treated by using heat, chemical treatments, or filtration. Each method has certain advantages and disadvantages that must be considered. In some situations, a combination of these methods may be preferred (e.g., filtration and chemical treatment).

Inspect the water before treatment. Microorganisms may be attached to or embedded in soil or other organic particles suspended in the water. The water to be treated should be allowed to stand so suspended material settles to the bottom of the container. Coarse materials like sand will settle more quickly than finer materials suspended in the water. During and after settling, care should be taken not to agitate the water. Water from the top of the container can be gently poured or drawn off into a second clean container. A second option for removing suspended particles is to strain the water through a clean cloth, layers of paper towels or paper coffee filter; do not use a commercially available portable water filter (see discussion on filters in this guide) for this step as the suspended material may rapidly clog such filters.

Contaminants in water which may cause illness or disease include bacteria, such as E. coli, protozoan cysts such as giardia or cryptosporidium, and viruses such as Hepatitis A. Giardia or cryptosporidium are not likely to be present in some groundwaters but may be encountered in contaminated surface waters. Viruses should be suspected in any water that may be contaminated with human waste.

Heat treatment

Heat kills microorganisms and is the oldest effective means of disinfecting drinking water. The process of bringing water to a boil will kill virtually any disease-causing organism including bacteria, cysts such as giardia and cryptospyridium, and viruses. Heat the water to a vigorous boil and then let it cool. There is some variation in recommendations regarding boiling time required for disinfection. It is important to realize that bringing water to a vigorous boil will adequately disinfect it. If fuel is not limited, however, additional boiling for one minute or keeping the water covered and hot for several minutes can provide an additional margin of safety. Since water boils at a lower temperature as elevation increases, the Centers for Disease Control and Prevention (CDC) recommends boiling for 3 minutes at altitudes above 6562 feet (2000 meters) in order to be certain that viruses are killed.

Though boiling effectively disinfects water for drinking, it does not provide a residual (or long-term disinfection). Therefore, care must be taken not to re-contaminate the water Boiled water may taste flat; the taste can be improved by pouring it back and forth between two clean containers to re-oxygenate it or by adding a pinch of salt to each quart after it has cooled.

Chemical treatments

Chlorine and iodine are the most commonly used chemicals for emergency disinfection of water. The killing effectiveness of the chemical depends on the concentration of the chemical in the water, the amount of time the available chemical is in contact with the water prior to use (contact time), the water temperature and the characteristics of the water supply. A de- creased concentration of the disinfectant or a lower temperature will require a longer contact time for adequate disinfection. If the water temperature is less than 410 F (or 50 C), it should be allowed to warm prior to disinfection or the chemical dose should be doubled. If the water is cloudy, it is recommended to strain it through a coffee filter before treatment.

A common objection to chemical disinfection is the flavor it gives to the treated water. If flavorings of any kind are added to the water to improve taste it should be done after the recommended contact time for disinfection. Flavorings added before adequate contact time has been achieved will “tie up” some of the chemical available for disinfection. Adding about 50 mg of vitamin C (ascorbic acid) per liter or quart of water after the contact time can improve the taste. Vitamin C is often avail able in 250 and 500 mg tablets where vitamin supplements are sold. Tablets should be pulverized and divided before adding to the water. In addition, freshness preservatives containing vitamin C are often available where canning supplies are sold.

Bacteria are very sensitive to chemical disinfectants such as chlorine and iodine. Viruses, cryptosporidium, and giardia require very high dosages of disinfectant or longer contact times with the disinfectant than the standard recommendations. Heat treatment is recommended if these pathogens are suspected in the water.

Chlorine

Regular household chlorine bleach that contains 5% to 6% sodium hypochlorite as the only active ingredient can be used for disinfection. Standard household bleaches are 5.25% sodium hypochlorite; those labeled “Ultra” are generally 6% sodium hypochlorite. Bleaches with labels such as “Fresh Wildflowers,” “Rain Clean,” “Advantage,” or labeled as scented may contain fragrances, soaps, surfactants, or other additives and should be avoided for drinking water disinfection. Using a medicine dropper, add 16 drops per gallon (4 drops per quart). Stir the water and let it stand covered for 30 minutes. For adequate disinfection, the water should have a slight chlorine odor to it after the 30 minute waiting period. If this odor is not present after the 30 minutes, repeat the dose and let it stand covered another 15 minutes. If this odor is not present, the bleach may have lost its effectiveness due to age of the product or exposure to light or heat. Present, the bleach may have lost its effectiveness due to age of the product or exposure to light or heat.

Use the freshest chlorine bleach available. If the chlorine taste is too strong in the treated water, taste can be improved by pouring the water from one clean container to another several times.

Halazone tablets are another form of chlorine for drinking water disinfection. The tablets are convenient and inexpensive but may require high doses and longer contact times. Follow manufacturer directions for use. Chemical treatment with chlorine provides some protection against recontamination since some available chemical remains in the water.

Iodine

Two forms of iodine commonly sold for chemical disinfection of drinking water are tincture of iodine (2%) and tetraglycine hydroperiodide tablets (Globaline, Coghlan’s and Potable-Aqua are examples). Iodine was once widely used, but is no longer recommended because health research has shown that as many as 8% of people have hidden or chronic thyroid, liver, or kidney disease which iodine can make worse. Iodine should not be ingested by children younger than age 14. Do not use iodine-containing products unless you have discussed the risks with your physician.

Filtration

Commercially available portable filters provide widely varying degrees of protection against disease-causing contaminants. The better filters provide adequate protection but less sophisticated filters on the market (often lower cost) may not provide protection. The more sophisticated filters typically operate by a hand pump which draws water into the filter through an intake hose or by slow gravity flow through a filter or series of filters. The filtration process works by physically within the filter medium. The size of contaminants retained depends on the pore size or the space between media fibers or granules. Most filters list an average pore size and are rated by the manufacturer according to the smallest particle they can trap. For example, a one micron (one thousandth of a millimeter) filter traps contaminants one micron in diameter or larger. The removal percentage of contaminants is affected by the amount of time the water is in contact with the filter media; shorter contact time with filter media generally results in less contaminant removal. Some filters have a chemical treatment component such as activated carbon, or iodine-impregnated resins which are effective against bacteria and some viruses. The contact time with the iodine in the filter may be too short to kill protozoan cysts, however.

Portable filters do provide immediate access to drinking water without adding unpleasant tastes or odors. However, as with boiling, the water can become re-contaminated after of 0.1 to 0.3 microns may be acceptable for cysts and bacteria but do not have small enough pore sizes to reliably remove viruses. While the filters may be reliable in remote areas where human waste contamination is unlikely, in populated areas filtration should be followed by either chemical disinfection with chlorine or boiling as described previously.

Proper selection, operation, cares and maintenance of portable water filters is essential for producing safe drinking water in emergency or short-term situations. When considering the purchase of a filter, be aware of the filter’s rating for pore size, output, pump strokes per liter, and pump force (how much effort is required to operate the pump). If size and speed are not critical factors, a gravity-fed drip filter that lets water slowly drip from a reservoir down through a filter may be a good option. Be aware that membranes in some filters can be damaged by chlorine in the water. Also, cloudy or turbid water can quickly clog a filter and shorten the life of the unit. When using a portable water filter, always follow the manufacturer’s instructions for use, care, and replacement.

Summary

Alternative drinking water sources for emergency situations and short-term use may include a stored emergency water supply that has been prepared ahead of time, bottled water, hidden sources of water within the home, and outside water sources. When a stored water supply or bottled water supply are unavailable, alternative water sources may be made acceptable for drinking by use of heat, chemical disinfection, filtration or an appropriate combination of these methods. Each method has advantages and disadvantages which should be considered for individual situations. If local public health department (or water utility) information differs from the recommendations in this guide, the local information should be followed. Local officials will be familiar with site- and event-specific conditions.

Earth Materials in Relation to Groundwater

Minerals and Rocks: Rocks and their weathering products are main components of the inorganic part of the earth . A rock, by definition, contains one or more minerals, and a mineral is defined by Hurlbut (1970) as follows:

“In addition to being natural and inorganic, a mineral must meet another requirement: it must be a chemical element or compound. It cannot be a random mixture of elements; the atoms that make it up must have definite ratios to each other, so that its composition can be expressed by a chemical formula. Not only are the proportions of the various atoms of a given mineral fixed, but so are their relative positions. These attributes give to each mineral a set of properties that characterize it so uniquely that one can distinguish it from all other minerals”.

A rock can be composed of one mineral or a mixture of several. For example, sandstone may contain grains of the mineral quartz (silica or SiO2), and a cement between the quartz grains composed of the mineral calcite (CaCO3). Granite is normally composed of crystals of the minerals feldspar, quartz, mica, and others. By definition then, frozen water (ice) is both a mineral and a mono-mineralic rock. The most fundamental of the three classes of rocks are igneous rocks, which are formed as cooling products from the molten state. Igneous rocks are primordial in many parts of the world and are some of the world’s oldest, exceeding three billion years in age. One way they can be formed is when molten rock is intruded into other rock formations and then cooled to the solid state. If the cooling is slow enough, various minerals will crystallize into an interlocking solid mass that is characteristic of particular rocks such as granite.

Extrusive igneous rocks like dense basalt are forced from fissures in the earth’s crust and harden into vast sheets of solid material, usually containing very small crystals (due to the rapid cooling), or perhaps no crystals at all (obsidian glass). Other extrusives like lighter lava or pumice are ejected during volcanic eruptions and are highly charged with gases to form very porous and even frothy glasses resembling a sponge. Some of the ejecta may fall from the air to settle as a sediment. This particular kind of deposit is known as a pyroclastic rock, i.e., both igneous and sedimentary.

A sedimentary rock, the second class, is deposited from either air or water as grains of rocks and minerals. These sediments in turn may have been derived from the weathering of igneous, metamorphic, or other sedimentary rocks.

If any kind of rock, igneous, metamorphic, or sedimentary, is subjected to intense heat and pressure, such as exists at great depths in the earth’s crust, at the edge of tectonic plates, or in rising mountain ranges, the parent rock will be transformed into the third class of rock — a metamorphic rock. A metamorphic rock may contain the same chemical composition as the parent rock, but the mineral composition and structure may be changed drastically from the parent. For example, limestone containing amorphous or cryptocrystalline calcite (CaCO3) is often metamorphosed into marble that has a definite crystal structure and is much harder than the original limestone. Granite may be metamorphosed into gneiss with the same overall chemical composition as the original granite, but with new minerals and mineral structures.

Groundwater can be found in all three classes of rocks, but in general, the sedimentary rocks contain by far the greatest amounts of water due to their greater porosity.

Unconsolidated Materials

Unconsolidated materials are those earth materials which have not been indurated. That is, the grains have not been fused together by heat and pressure, as in the cases of igneous granite or metamorphic gneiss; or cemented together, as in the case of sedimentary rocks. Unconsolidated materials can be the non-indurated products of weathering of all three classes of rocks, or sediments laid down by running water, ponded water, the sea, or ejecta from volcanoes.

Most unconsolidated materials are young, geologically speaking, and are at or near the earth’s surface. Thus, they have not been exposed to pressure, heat, and migrating cementing fluids long enough to become consolidated or hard. Hence, they generally have high porosity and are the sources for much groundwater.

A common unconsolidated deposit in glaciated areas of the world is glacial drift. It is any kind of earth material that was deposited directly by glaciers or by meltwater from glaciers. As such, it can range in size from the finest silt to the largest boulders, and can be mixtures of all sizes. The name “drift” was given to this material when it was believed that it was depositional material, or “drift,” from the great Noachian Flood, described in the Book of Genesis. Drift can generally be subdivided into the more specific lithologies such as till and outwash.

Glacial till is a generally heterogeneous mixture of many different lithologies and particle sizes. Typically in the midwestern U.S., till contains a preponderence of clay and silt with additional amounts of groundup rocks and boulders that may vary in size from small pebbles to erratics the size of a house or larger. On rare occasions, geologists find tills composed of one lithology, indicating local sources of material. Glacial till is not generally utilized as a source of groundwater because of its low permeability.

Glacial outwash is material deposited from high-energy streams of water that originated from melting glaciers. This process can be seen today at the toe of any mountain glacier on different continents.

Glacial ice, more often than not, contains entrained rock and soil material which it has eroded from the surrounding valley sides or the ground beneath it. This material varies widely in size from clay to large boulders. As the ice melts and leaves the toe of the glacier, normally in great flow rates and very turbulent, this material is moved with the flowing water. As the stream loses energy, materials settle out, with larger material coming out first, followed by gradually smaller material. Therefore, along a stretch of an outwash stream one may find coarse gravel and boulders settling out first, followed by finer gravel, then sand and gravel mixtures, then sand, silt, and finally clay (in still water).

Many present-day stream courses were glacial spillways for outwash water and sediment during the Pleistocene Epoch (Ice Age). For example, the Wabash River Valley in Indiana contains outwash sand and gravel deposits in excess of 300 feet in thickness which were deposited by the melting of two and possibly three different ice sheets. The Big Sioux River valley in South Dakota and Iowa is another example. A very extensive deposit of outwash sand is the Cape Cod peninsula which was deposited in an interlobate outwash between two lobes of ice — one to the east and one to the west of the site. Outwash sand and gravel deposits are frequently exploited for groundwater because of their high porosity and permeability. Well yields in many of these deposits often exceed 5500 m3/d.

Other water-lain deposits not directly deposited from glacial meltwater may be comprised of reworked glacial detritus (glacially transported material), or they may be found in areas where glaciers never occurred. The most common example of such deposits is alluvium. Flood plains along large streams are created of this material as the streams flood over their banks and deposit the material. Stream beds also contain alluvium.

In fast-flowing streams with high gradients, as in mountainous areas, alluvium may be absent because the stream is eroding rather than depositing material. If alluvium is found in and along such streams, it is generally very coarse-grained gravel with large boulders. On the other hand, mature streams such as the Ohio, Missouri, and Mississippi Rivers, deposit their loads of fine silt and clay over broad flood plains.

Alluvium deposits may serve as important groundwater sources, but in large river valleys, the yield of such deposits may be low to moderate, depending on the grain size and the resulting permeability and

porosity.

Lacustrine materials are silts and clays that are deposited from relatively still bodies of water such as lakes and lagoons. This material, being so fine-grained, is not utilized for groundwater supplies because of its low permeability.

Peat is the remains mostly of water plants that die and accumulate in ponded water and marshes over long periods of time. The top part of a peat deposit is very porous and permeable, but it becomes more compact with depth. The lower layers of peat are often sticky masses of black organic material with little resemblance to the original plant material.

Peat is not generally utilized as a groundwater source, but it can serve, under the right conditions, as a natural cleansing agent to remove organics and heavy metals from water that passes through it — the large and complex organic molecules in the peat attract such contaminants.

Chemical precipitates of most importance include limestone and marl which precipitate directly from sea water or even from fresh water bodies. Major deposits of limestone were deposited in many parts of the world during the Cretaceous Period (the “Chalk Period”) of the Mesozoic Era. Examples include the Chalk Beds of Dover, England; the limestones of the Balkan Peninsula; and limestones of the High Plains in the United States. Other vast limestone deposits were formed in earlier times and are found across most of the midwestern U.S. and the Appalachians.

Limestone is composed primarily of calcite. Entrained silt and clay and other materials may also be present. After deposition, a process known as diagenesis often takes place in which the rock incorporates magnesium to become dolostone, or CaMg(CO3)2; this is also the formula for the mineral, dolomite. Pure MgCO3 is the mineral, magnesite.

Collectively, limestone and dolostone are called “carbonate rocks,” or “carbonates.” Carbonates, especially limestone, often undergo solution along bedding planes and fractures to form caves and sinkholes, which in an interconnected system, is known as karst terrane, after the Karst region in Yugoslavia. Networks of such caves and tunnels may exceed hundreds of miles in length and may contain large streams which emanate from springs in the rock.

Examples of such systems are found in the Balkan Peninsula, the Mediterranean area, France, Kentucky (Mammoth Caves), and New Mexico (Carlsbad Caverns), to name just a few. Karst systems are often sources of very large quantities of groundwater, and due to the very high permeability, can be productive aquifers. A drawback, though, is the ease with which water in karst systems can be contaminated by surface sources. Thus, care must be taken to protect such sources.

Aeolian deposits are fine-grained materials, such as silt and sand, which may have been deposited originally from water, but which have been reworked and redeposited by wind. Examples of such active deposits today can be found in sand-dune areas of the Sahara, the Middle East, New Mexico, Nevada, and many other places.

Ancient dunes from the geological past are often found as sandstone bodies and may have some potential for groundwater extraction if coarse enough to allow sufficient porosity and permeability. Generally, wind-blown deposits are fine-grained, and when cemented with precipitates from circulating groundwater, may possess low porosity and permeability. The finest-grained aeolian deposits are composed of silt or “rock flour” known as loess. The silt source is usually a wide river bed with braided channels where large dry areas of fine-grained materials are exposed to the wind. In most cases, the silt was deposited in such rivers as the end product in the long chain of deposition of glacial outwash. Prevailing winds then pick up the silt and transport it downwind where it is deposited on the lee sides of river valleys.

Significant loess deposits are found on the east side of the Missouri River, which acted as a glacial spillway during the Pleistocene. North of Sioux City, Iowa, this material forms bluffs which are tens of meters high. Other noteworthy deposits are found along the Mississippi River (another spillway) and in the Gobi Desert of China.

Loess, after deposition, will often be reworked by frost action to form columnar structures with vertical fractures. The grains of silt are then oriented with their long axes vertically to form such features. With this alteration, it will allow fast vertical movement and drainage of water and is fairly solid material to build upon, but its permeability is too low to utilize it for a groundwater supply.

Installation of Gas Pipes

Installation, repair and replacement of gas piping or appliances shall be performed only by a qualified installing agency or gas fitter.

Protection of piping

Piping shall be buried to a sufficient depth or covered in a manner so as to protect the piping from physical damage. Measures should be taken to protect the piping from physical damage when it passes through flower beds, shrub beds and other such cultivated areas.

Protection against corrosion

Gas piping in contact with earth or other materials which will corrode the piping shall be protected against corrosion in an approved manner. When dissimilar metals are joined underground, an insulated coupling shall be used. Metallic piping shall not be laid in contact with cinder or ash.

Piping through foundation wall

Underground gas piping, when installed below grade through the outer foundation or basement wall of building, shall be either encased in a sleeve or otherwise protected against corrosion. The piping or sleeve shall be sealed at the foundation or basement wall to prevent entry of gas or water. 

Piping underground beneath buildings

If the laying of gas piping underground beneath buildings can not be avoided, the piping shall be encased in a conduit. The conduit shall extend into a normally usable and accessible portion of the building and, at the point where the conduit terminates in the building, the space between the conduit and the gas piping shall be sealed to prevent the entrance of gas from any possible leakage. The conduit shall extend at least 100 mm outside the building, be vented above grade to the outside and be installed in such a way as to prevent the entrance of water and moisture.

Building structure

The building shall not be weakened by the installation of any gas piping. Existing beams and joists shall not be cut or notched.

Piping supports

Gas piping in buildings, shall be supported with pipe hooks, metal pipe straps, bands or hangers of an approved type and material suitable for the size of piping, and located at specified intervals so that the piping cannot be moved accidentally from the installed position. Gas piping shall not be supported by other piping.

Piping entrance to buildings

When gas pipe enters a building through a wall or floor of masonry or concrete, it shall be sealed against the entrance of water, moisture or gas.

Piping in floors

Piping in solid floors, such as concrete, shall be laid in a channels in the floor suitably covered to provide access to the piping with a minimum damage to the building.

Changes in direction of gas pipe shall be made by the use of approved fittings, factory bends or field bends. Field bends shall be made by employing approved procedures and equipment.

Gas piping inside any building shall not be run in or through an air duct, chimney or gas vent, ventilation duct or elevator shaft. Gas piping shall not be taken through inaccessible or concealed areas where its condition cannot be inspected and accumulation of gas due to undetected leakage may create a dangerous condition.

Provides Drips Where Necessary

A drip shall be provided at any point in the line of pipe where condensate may collect. When condensation is excessive, a drip should be provided at the outlet of the meter. This drip should be so installed as to constitute a trap wherein an accumulation of condensate will shutoff the flow of gas before it will run back into the meter. All drips installed shall be readily accessible to permit cleaning, inspection or emptying. 

Cap All Outlets

Each outlet, including a valve or cock outlet, shall be firmly closed gas tight with a threaded plug or cap immediately after installation and shall be left closed until an appliance is connected thereto. Similarly, when an appliance is disconnected from an outlet and the outlet is not to be used again immediately, it shall be firmly closed gas-tight. The outlet shall be closed with tin caps, wooden plugs, corks or by other improvised means or objects. Use of a listed quick disconnect device is acceptable.

Prohibited Devices

Any device that will reduce the flow cross-sectional area or otherwise obstruct the free flow of gas shall not be inserted or placed inside the gas pipe or fittings.

Branch Pipe Connection

All branch pipe connections and outlets shall be taken from the top or sides of horizontal lines and not from the bottom.

Electrical Bonding and Grounding

The gas piping shall be electrically continuous throughout its length and earthed except in sections where cathodic protection system is used for protection against corrosion. The piping shall not be used to ground any electrical equipment.

Distance from Electrical Wiring

The distance between the gas piping and electrical wiring system shall be at least 60 mm. They shall be fixed to prevent contact due to movement. The gas piping should be installed below the electrical wiring. 

Distance from Stream piping

The gas piping and stream piping,if installed parallel, shall be at least 150 mm apart. The gas piping should preferably be installed below the steam piping. 

Gas piping to be Graded

All gas piping shall be graded not less than 1 in 750 to prevent accumulation of condensate or liquids in the line. All horizontal lines shall graded to risers, and from the risers, to the meter, or service regulator when there is no meter, or to the appliance.

The gas piping shall be painted red in order to differentiate it from other piping. Where the piping is exposed to sun rays, it shall be painted silver gray.

Documentation shall be maintained for all gas supply installations.

Ventilation Systems

Where required

Every space intended for human occupancy shall be provided with ventilation by natural or mechanical means during the periods when the room or space is occupied.

Natural ventilation

Sources

Natural ventilation of an occupied space shall be through windows, doors, louvers, skylights or other openings to the outdoor. Such ventilating openings shall open to the sky or a public street, space, alley, park, highway, yard, court, plaza or other approved space which comply with the requirements of the building code.

Area of ventilating openings

The minimum ventilating opening to the outdoors shall be 4% of the floor area being ventilated.

    Adjoining spaces

Where rooms and spaces without opening to the out doors are ventilated through an adjoining room, the unobstructed opening to the adjoining rooms shall be at least 8% of the floor area of the interior room or space, but not less than 2.33 m². The ventilation openings to the outdoors shall be based on the total floor area being ventilated.

    Opening below grade

Openings below grade shall be acceptable for natural ventilation provided the out side horizontal clear space measured perpendicular to the opening is one and one-half times the depth below the average adjoining grade.

Contaminants exhausted

Naturally ventilated spaces having contaminants present shall comply with the requirements of Mechanical exhaust will discuss later.

Lp-gas distribution facilities

Lp-gas distribution facilities shall be provided with air inlets and outlets arranged so that air movement across the floor of the facility will be uniform. The total area of both inlet and outlet openings shall be at least 0.7% of the floor area. The bottom of such openings shall not be more than 150 mm above the floor.

Design Considerations for Drainage and Sanitation System

Objective of design

For the design of drainage and sanitation system of different buildings according to building classification, the objective shall be to safeguard against fouling, deposit of solids and clogging and with adequate cleanouts and inspection chambers so arrange that the may be readily cleaned without the risk of health hazard.

a) The plumbing system shall be designed and adjusted to use the minimum quantity of water consistent with proper performance and cleaning.

b) Plumbing fixtures, devices and appurtenances shall be supplied with required volume of water at pressures adequate to enable these to function properly and without undue noise under normal conditions of use.

Different plumbing systems

For the design and installation for drainage piping, one of the following plumbing systems shall be used:

1) Single stack system,

2) One-pipe system, and

3) Two-pipe system.

1) A single stack system may be used with 100mm diameter stack foe buildings up to 5-storey height. The fixtures in each floor shall be connected to a single stack for increasing the rate of discharge in the downward direction. There shall be at least 200 mm vertical distance between the waste branch and the soil branch connection, while the soil pipe will be connected to stack above the waste pipe. The size of soil branch shall not be less than 100mm. The horizontal branch distance for fixtures from stack and bend(s) at the foot of stack to avoid back pressure as well as the vertical distance between the lowest connection and the invert of drain shall be shown in Fig -1. The recommended depth of water seal trap for different fixtures shall be in accordance with Table-1.

Lightning Protection of Buildings

Whether a building needs protection against lighting is matter of judgment on the part of designer; obviously it depends on the probability of a stroke and acceptable risk levels. For example, a higher risk is presumably acceptable for an isolated small bungalow than, say, for a children’s hospital. Whilst no exact rules can be laid down which would eliminate the designer’s judgment entirely, certain steps can be taken for an objective assessment of the risk and of the magnitude of the consequences. As an aid to making a judgment, a set of indices is given in table-1 and elaborated below for the various factors involved.

Usage of structure

The lightning hazard to human being within structure or a building is a very important in deciding how far to go in providing lightning protection. Schools, hospitals, auditoriums, railway stations etc., are places where a large number of people congregate and, therefore, would in general be structures of greater importance than small buildings and houses.

Type of construction

The type of construction of the structure has a large influence upon the extent of protection to be provided. A steel framed building to some extent is self-protecting and may not generally required additional protection, while brick buildings or buildings with thatched roof require greater degree of protection.

Contents or consequential effects

In addition to direct loss due to destruction of buildings by lightning, fire resulting from lightning, killing of livestock etc. there may be indirect losses which sometimes accompany the destruction of buildings and there contents. An interruption to business or to firming operations, especially at certain times of the year, may involve losses quite distinct form, and in addition to losses arising from the direct destruction of property. There are also cases where full community depends for safety and comfort in some respect on the integrity of a single structure, as for instance on the brick chimney of a water pumping plant. A lightning strike to it may have a serious consequence due to disruption of sanitary facilities, drinking water, water for irrigation, fire protection etc. the contents of buildings should also be considered as to whether they are replaceable, explosive, combustible, flammable vapor or explosive dust. These may present a hazard in a building that is otherwise immune to lightning. Contents like hay or cotton may make protection measures especially desirable.