8. Sanitation - World Health Organization
Contents
1. Once a month check tank outflow pipe and Water clean it Brush tools to open the access hole Once every 6 12 months switch to another drainage field Bricks or other material to block pipes Tools to open the diversion box Occasionally unblock the delivery pipe Water piping glue Brush shovel long stick or flexible brush knife saw 8 11 5 Potential problems overflowing leachlines unpleasant odours groundwater contamination and so cial conflict over siting of the drainage fields odours etc there is not enough water to use or maintain the system there is not enough space or financial resources for construction the permeability of the soil is poor the bedrock or groundwater are close to the surface 8 12 Small bore sewerage system 8 12 1 The technology Small bore sewerage or settled sewerage systems are designed to receive only the liquid fraction of household wastewater The solid component of the wastewater is kept in an interceptor tank basically a single compartment septic tank and settles out Periodi cally the interceptor tank will need to be desludged Because small bore sewers only 1 Reed 1995 Mara 1996 8 SANITATION 6 122 127 receive liquid sewage they are designed differently from conventional sewers and have the following advantages the system uses less water since solids do not need to be tr2. Water Basic mechanical tool set When needed repairs and removal of blockages Water specialized materials and spare parts Rodding tool mechanical tool set 8 12 5 Potential problems the interceptor tanks overflow because they have not been desludged in time the system becomes blocked because of illegal connections that by pass the inter ceptor tank small bore sewerage systems are basically only suitable where there are septic tanks or other on site systems the need to desludge the interceptor tank regularly requires the involvement of a well organized sewerage department
3. carry out regular maintenance according to the service manual including chang ing the engine oil oil filter and fuel filter and greasing all points change the hydraulic oil hydraulic filter and cooling oil clean the cooling oil filter after one year or sooner if required The vacuum truck service and its O amp M are usually organized and executed by a profes sional organization normally under the responsibility of the municipality User fees for the service are usually set officially and often heavily subsidized either by the organiza tion or the government There is very little involvement of the households being served Management and supervision of the services are often ineffective In many areas for example there are not enough vacuum tankers which results in poor service 8 8 3 Actors and their roles Actors Roles Skills required Truck driver Driving the truck simple checks and maintenance of the truck K Crew member Some maintenance activities operating the vacuum pump and K desludging Mechanic Major maintenance and repairs KK Government or Organizing the service ensuring that the sludge is disposed of KEK private organization hygienically Basic skills 44 Technical skills 4 44 Highly qualified 8 SANITATION 8 8 4 O amp M technical requirements 121 Activity and frequency Materials and spare parts Tools and equipment Daily before work
4. After each defecation or whenever available add ashes or other organic Wood ashes and organic material Pot to contain the material small material shovel Monthly inspect the floor superstructure and vaults When necessary repair the floor superstructure or Cement sand water nails local Bucket or bowl trowel saw vaults building materials hammer knife use humus as fertilizer Humus Shovel bucket wheelbarrow Depending on size and number of users close the full vault after levelling Water absorbent organic material Shovel and bucket and adding soil empty the other vault open its squat hole and add 10 cm of absorbent organic material before using store the humus or use it directly 8 4 5 Potential problems users do not understand how to operate the system properly and leave the latrine contents too wet which makes the vault malodorous and difficult to empty users are too eager to use the latrine contents as fertilizer and do not allow suffi cient time for the compost to become pathogen free the double vault compost latrine can only be used where people are motivated to use human excreta as a fertilizer the double vault compost latrine is not appropriate where water is used for anal cleansing 8 SANITATION 8 5 8 5 1 8 5 2 n5 Bored hole latrine The technology Mainly used in emergency situations A bored hole
5. 103 8 Sanitation 8 1 Introduction Sanitation includes solid waste disposal including medical wastes wastewater disposal wastewater reuse human excreta disposal and drainage of surface rain water This section deals mainly with systems for human excreta disposal in line with the scope of this document A distinction is made between systems that do not need water dry sys tems and systems that need water to function waterborne systems The following sys tems are described in the Fact Sheets and they cover a wide range of technologies for disposing of human excreta from simple improved traditional latrines to complex sew erage systems basic improved traditional latrine ventilated improved pit latrine double vault compost latrine bored hole latrine pour flush latrine with leaching pit septic tank and aqua privy vacuum tanker manual latrine pit emptying technology MAPET soakaway drainage field small bore or settled sewerage Sludge and effluent treatment technologies such as stabilization ponds and aeration ponds are not included as they are beyond the scope of this publication Bucket collec tion of excreta also has not been included because the collection transportation and disposal of excreta by this method are usually uncontrolled and unhygienic and pose health risks both to the collectors and to the community Safe human excreta disposal is crucial
6. keep insects out of the pit n Porous lining afloor raised at least 0 15 m above ground level to prevent flooding i an adequately lined pit to prevent Figure 8 2 Traditional pit latrine the pit collapsing e g when the soil is unstable an adequate foundation to prevent damage of the slab and superstructure The pits can be square rectangular or circular usually 1 0 1 5 m wide The depth usu ally 3 5 m depends on the soil and groundwater conditions In unstable soil or when the pit is going to be emptied some kind of lining e g old oil drums or stones is needed A foundation may be needed to support the slab and superstructure As a general rule pits should be at least 15 30 m from sources of drinking water The actual distance will depend on local hydrogeological conditions such as soil characteris tics and groundwater depth and flow When groundwater levels are high or when the soil is too hard to dig the pit latrine may have to be raised above ground level Initial cost Initial costs of construction should include materials 50 80 transporta tion 0 25 and local labour 15 35 Actual costs will depend on the pit volume the quality of the pit lining slab and superstructure whether materials are available locally and the local costs of materials and labour Area of use Rural and low income urban areas Mainly used as a household facility and for rural institutions
7. Initial cost A single pit system costs US 30 100 and a double pit system US 75 212 The prices include costs for labour Diversion Leach pits chamber and materials and for a brick liningand fa a concrete platform the superstructure was not included in most cases Organi zational costs are also not included The lowest prices were in Asia the highest in Africa and those in South America were between the two Area of use Rural or periurban areas where sufficient water is available and the soil is permeable Figure 8 6 Pour flush latrine Flushing About 2 5 litres per flush mainly depending on the pan design and the distance to the pit Main O amp M activities Before use the pan is wetted with a little water to prevent faeces sticking to the pan After use the pan is flushed with a few litres of water If water is scarce water already used for laundry bathing etc may be used No material that could obstruct the U trap should be thrown into the pan The floor squatting pan or seat door handles and other parts of the superstructure should be cleaned daily with brush soap and water Wastewater from bathing or washing clothes should not be drained into the pit except when used for flushing but disposed of elsewhere Monthly the pan and U trap should be checked for cracks and the diversion box for blockage If the excreta does not flush quickly the PVC pipes or diversion box may b
8. Main O amp M activities Operation of pit latrines is quite simple and consists of regularly cleaning the slab with water and disinfectant to remove any excreta and urine The tight fitting lid over the drop hole should be replaced after use to ensure insect control and to reduce odours In 1 Sources Wegelin Schuringa 1991 Franceys Pickford amp Reed 1992 LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 106 TABLE 8 1 WHAT TO DO WITH A FULL PIT LATRINE 1 Stop using the latrine 2 Empty latrine by hand 3 Empty by simple mechanical means 4 Empty using a tanker Back fill the top of the latrine with soil and build another If possible build twin pit latrines which are shallow and reusable Dig out the contents of the latrine using a spade and bucket Use a simple device e g MAPET with a manpowered suction pump that is easy to manoeuvre in narrow streets and courtyards Use a motorized tanker with a vacuum pump Limitation s e Many families or schools do not have sufficient space to build another latrine and they continue to use the one they have This creates very high health risks Limitation s e This method involves very high health risks e If the pit is not lined with walls of stones bricks or concrete it might collapse when it is emptied e Sludge could be deposited in an unsafe place Limitation s e The informal sector does not
9. buckets wheelbarrow etc empty the old pit if applicable By hand water By hand shovel bucket By mechanical means water and By mechanical means equipment spare parts for the machinery for emptying the pit 8 3 5 Potential problems the quality of the floor slab is poor because inappropriate materials were used in its construction or because the concrete was not properly cured inferior quality fly screens are easily damaged by the effects of solar radiation and foul gases badly sited latrines can get flooded or undermined children may be afraid to use the latrine because of the dark or out of fear of falling into the pit if the superstructure allows too much light to come in flies will be attracted to the light coming through the squat hole and may fly out into the superstructure which can jeopardize the whole VIP concept in latrines that rely on solar radiation for the air flow in the vent pipe rather than on wind odour problems may occur during the night and early morning hours leakage between pits occurs because the dividing wall is not impermeable or the soil is too permeable in hard soils it may be impossible to dig a proper pit pits should preferably not reach the groundwater level and must be 15 30 m from ground and surface water sources VIP latrines do not prevent mosquitoes from breeding in the pits VIP latrines cost more to construct than simple pit latrines and the community may not be able to
10. If sullage is also collected in the tank the capacity of both the tank and the liquid effluent disposal system will need to be larger If the soil has a low perme ability or if the water table is high it may be necessary to connect the tank to a sewer system if available Every tank must have a ventilation system to allow methane and malodorous gases to escape The gases are generated by bacteria during sewage decomposition and methane in particular is highly flammable and potentially explosive if confined in the tank Septic tanks are more expensive than other on site sanitation systems and require higher amounts of water Aqua privies are slightly less expensive and need less water for flushing Initial cost US 90 375 including labour and materials Area of use In rural or periurban areas where water is available Water needed per flush 2 5 litres if a pour flush pan or aqua privy is used 1 Kaplan 1991 Wegelin Schuringa 1991 Franceys Pickford amp Reed 1992 LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 118 8 7 2 Main O amp M activities Regular cleaning of the toilet with normal amounts of soap is unlikely to be harmful but large amounts of detergents or chemicals may disturb the biochemical processes in the tank In aqua privies the amount of liquid in the tank should be kept high enough to keep the bottom of the drop pipe at least 75 mm below the liquid level A bucket of water should be poured
11. always have the necessary equipment e The suction pump may not be powerful enough to raise sludge from a deep latrine e If the pit is not lined with walls of stones bricks or concrete it could collapse when it is emptied e Sludge could be deposited in an unsafe place Limitation s e Large vehicles have problems manoeuvring in narrow streets and courtyards e Motorized tankers are expensive to buy e Users pay more for the service v Adapted from Pickford amp Shaw 1997 A full pit latrine is defined as one that is filled to within one half metre of ground level TABLE 8 2 WHAT TO DO WITH SLUDGE FROM PIT LATRINES AND SEPTIC TANKS Possible solutions Method Disposal into water Sludge can be disposed into water if it is left untouched for about 2 years However untreated sludge poses very high risks to health and the environment Disposal onto land Sludge can be disposed onto land if it is left untouched for about 2 years However untreated sludge poses very high risks to health and the environment Composting Mix the sludge with 2 3 times its volume of vegetable waste Turn it several times in the first few weeks then heap it into a pile and leave it for several weeks After this it can be used as fertilizer Household bio gas units Add latrine or septic tank sludge to bio gas units mainly used with animal waste Drying beds Sludge flows into a sha
12. check oil levels water levels and cooling radiator for the hydraulic oil and pump oil Oil water oil filters and other simple spare parts for the truck Simple tool set for truck maintenance Daily after work drain the sludge and oil separators Simple tool set for truck maintenance bucket Daily or more frequently fill in forms carry out administrative tasks Paper Pen empty the tank Weekly weekly checks Oil water grease oil filters and other simple spare parts for the truck Simple tool set for truck maintenance Every 1 2 weeks depending on tanker type superstructure clean the vacuum Water soap Brush bucket pump remove and clean washwater filter After one year or when required change the hydraulic oil hydraulic Oil filters etc Simple tool set for truck filter and cooling oil and clean the cooling oil filter maintenance According to manual service truck chassis and engine Standard and specialized spare parts for trucks Simple mechanics workshop grease the points clean and grease the safety valves Grease Simple tool set for truck maintenance Occasionally repair the superstructure Standard and specialized spare parts for superstructure Mechanical workshop tools check vacuum pump bearings Grease water Mechanical workshop tools 8 8 5 Potential probl
13. densities and areas where pour flush latrines with soakpits can be upgraded to a small bore sewerage system Main O amp M activities The main operational requirements for the household are to ensure that no solids enter the system and that the interceptor tank functions properly This should be checked by the local sewerage authority because the system will be at risk if solids can enter The sludge in the interceptor tank also needs to be removed regularly and blockages in the sewage pipes removed The system will also need to be flushed periodically The per formance of the pipeline system components such as cleanouts manholes lift stations possibly and ventilation points should be regularly checked and maintained The main organizational activity with the system is to provide desludging services for the interceptor tanks The principal problems related to desludging revolve around re sponsibility Normally this lies with the property owners since the interceptor tanks are on their property But residents who are not owners have no incentive to desludge the tanks regularly since this costs money and is inconvenient and the overflowing sludge in the sewerage system does not directly affect them even though it will affect the commu nal sewerage system downstream If the sewer system is to work effectively therefore LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 128 responsibility for tank desludging must fall on
14. density settle ments with narrow streets where conventional vacuum tankers have no access The maxi mum width of the MAPET for example is 0 8 m Motor driven vacuum tankers built on small tractors are available and they use the same principle as the MAPET Initial cost US 3000 in Dar es Salaam Tanzania in 1992 dollars Muller amp Rijnsburger 1994 The price included the costs of procuring all the parts and materials locally gas welding rods paint transportation and labour for assembly Area of use In unplanned and low income urban areas especially where access for motor vehicles is poor and where double pit systems cannot be applied Cost of operation In 1992 US 2 50 per tank load of 200 litres in Dar es Salaam Tanza nia Muller amp Rijnsburger 1994 Main O amp M activities The emptying job starts with contacting the customer negotiating the price picking up the MAPET equipment from its parking place and taking it to the customer s house which may take from 30 60 minutes A hole is dug for sludge disposal and the latrine sludge is prepared for pumping This preparation entails mixing the sludge with water to make it more liquid and paraffin to reduce the smell After connecting the hosepipes the sludge can be pumped Depending on the viscosity of the sludge and the pumping head it can take 5 20 minutes to fill up one 200 litre tank with sludge When a tank is full the hosepipes are disconnected and the t
15. for preventing the spread of infectious dis eases Communities and planners need to realize that safe human excreta disposal brings about huge health benefits The control and management of wastes are an essential part of O amp M In rural areas the users themselves are largely involved in preventive mainte nance activities for wastewater and solid waste disposal Awareness campaigns and in volving the community in sanitation problems can both help to change behaviour in communities and improve the O amp M of basic sanitation systems Factors to consider when choosing a sanitation system for excreta disposal include the initial cost of the technology and the costs of O amp M demand and use what is the population density and will the system be used in homes schools market places climate temperature humidity and rainfall soil and topography infiltration properties of the soil and what is the direction of the groundwater flow water availability for waterborne systems cultural beliefs values and practices around sanitation LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 104 the availability of technical skills are there local craftsmen or technicians with the necessary skills to install and or carry out O amp M of the system agriculture what are the characteristics of the local agriculture and home gar dening 8 1 1 Waterborne systems for excreta disposal 8
16. latrine is similar to a basic im proved traditional latrine but the pit is a hole bored with a soil auger either me chanically or manually The borehole diameter is at least 0 4 m and the pit is 4 10 m deep The relatively small diam eter permits a simpler smaller lighter and cheaper floor slab and foundation Mouna but limits the storage capacity A bored hole latrine is suitable for stable perme tining AA able soils free of stones and where the groundwater is deep beneath the sur face The top 0 5 m of the pit is often Bore hole lined to provide support for the slab but the pit is not lined all the way to the bot tom oe Figure 8 5 Bored hole latrine Initial cost There are no hard data on prices Costs would depend on the soil and other local conditions labour costs the materials used in building the latrine and the efficiency of organization Area of use Emergency areas with permeable stable soils low groundwater and no stones Main O amp M activities Operation of the latrines is quite simple and consists of regularly cleaning the slab with water and disinfectant The tight fitting lid should be replaced after use to control in sects and reduce smell In addition appropriate anal cleansing materials should be avail able in or near the latrine Ash or sawdust can be sprinkled in the pit to reduce odours and insect breeding Nonbiodegradable materials such as stones glass plastic r
17. not suitable if it is common practice to use bulky materials such as corncobs or stones for anal cleansing because they cannot be flushed through the U trap an offset system requires more water for flushing than a direct pit system 8 7 Septic tank and aqua privy 8 7 1 The technology Septic tanks and aqua privies have a wa ter tight settling tank with one or two compartments Waste is flushed into the tank by water from a pipe that is con nected to the toilet If the septic tank is under the latrine the excreta drop di rectly into the tank through a pipe sub merged in the liquid layer aqua privy i If the tank is away from the latrine sep tic tank the toilet usually has a U trap Neither system disposes of wastes they only help to separate the solid matter from the liquid Some of the solids float Septic tank Soakaway eh on the surface where they are known as __ Figure 8 7 Septic tank scum while others sink to the bottom where they are broken down by bacteria to form a deposit called sludge The liquid effluent flowing out of the tank is as dangerous to health as raw sewage and should be disposed of normally by soaking it into the ground through a soakaway or by connect ing the tank to sewer systems The accumulated sludge in the tank must be removed regularly usually once every 1 5 years depending on the size of the tank number of users and kind of use
18. repairs x committee Health department Monitor latrines and hygiene behaviour of users train users in KKK hygienic practices Simple often requires gender specific awareness raising and training activities to change behaviour and build capacity Basic skills 4 Highly qualified 8 5 4 O amp M technical requirements Activity and frequency Materials and spare parts Tools and equipment Daily clean the drop hole and Water soap Brush superstructure Monthly inspect the floor slab and lid Occasionally repair the slab lid or Cement sand water nails local Bucket or bowl trowel saw superstructure building materials hammer knife 8 5 5 Potential problems the small diameter of the hole increases the chance of blockage the sides of the hole become soiled near the top leading to fly infestation the pit cannot be bored because the soil is too hard or too stony etc in which case a dug latrine may be more appropriate as bored holes are relatively deep there is a risk of groundwater contamination 8 6 Pour flush latrine 8 6 1 The technology Pour flush leaching pit latrines overcome the problems of flies mosquitoes and odour by having a pan with a water seal a U shaped conduit partly filled with water in the defeca tion hole After using the latrine it is flushed by pouring water in the pan The latrine pits are usually lined to strengthen the wa
19. saw hammer knife Depending on size and users close a full pit with soil and dig a new pit in the case of a single pit system Soil several local building materials and nails Shovels picks bucket hammer knife saw etc or empty the pit By hand water By mechanical means water spare parts for machinery By hand shovel bucket By mechanical means pit emptying equipment divert excreta flush to the other pit in the case of a double pit Water sand cement bricks clay etc Shovel bucket 8 6 5 Potential problems the U trap becomes blocked because of bad design or improper use the U trap is damaged because the unblocking was not done correctly sometimes U traps are broken on purpose to prevent blockage 8 SANITATION 117 diversion boxes or PVC pipes become blocked excreta in double pits may not decompose completely because the pits are too close to each other without an effective seal between them and liquids percolate from one pit to the other full flush pans are sometimes used when pour flush pans are not available but they require more water 7 12 litres per flush which may be a problem if water is limited leaching pits only function in permeable soils latrines must be 15 30 m from water sources pour flush latrines should only be used in areas with adequate water for flushing pour flush latrines are
20. seat and shelter Water soap Brush clean the handle of the lid Water soap Brush Monthly inspect the floor slab and lid Occasionally repair the slab lid seat or Cement sand water nails local Bucket or bowl trowel saw superstructure building materials hammer knife Depending on size and number of users close the pit with soil dig a new Soil local building materials and nails Shovels picks bucket hammer pit shift cover and superstructure if available knife saw etc empty the pit if applicable By hand water By hand shovel bucket By mechanical means water spare By mechanical means equipment parts for machinery for emptying the pit LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 108 8 2 5 Potential problems the slab floor cracks because it was constructed with unsuitable materials or be cause the concrete was not cured properly and the cracks provide a habitat for parasites the latrine lid gets damaged or falls into the pit in hard soils it may be impossible to dig a proper pit pits often fill up too quickly in soils with low infiltration and leaching capacity when children are afraid of using a latrine special children s latrines may be con structed with a smaller drop hole 8 3 Ventilated improved pit latrine 8 3 1 Brief description of the technology Ventilated Improved Pit VIP latrines are designed to red
21. use In rural or periurban areas where sufficient water is available the soil is permeable and there is no bedrock or groundwater near the surface Main O amp M activities Hardly any activities are required to operate the system except when the soakaway or septic tank overflows Then the tank outflow should be cleaned and the delivery pipe unblocked if necessary 8 10 3 Actors and their roles Actor Roles Skills required Householder user Check the outflow tank and performance of the soakaway K or local caretaker Local artisan Repair broken parts remove obstructions in delivery pipes KM Agency department Monitor performance of the systems train users caretakers and KEK local artisans provide assistance with big problems Basic skills 56 Technical skills 3 Highly qualified 8 10 4 O amp M technical requirements Activity and freq uency Materials and spare parts Tools and equipment Once a month check the outflow of the tank Water boxes and clean them Brush tools to open the access Whenever necessary repair the pipe connection to the Water materials for soakaway dismantling pipes Brush shovel and tools to open the access and to dismantle connector pipes 1 National Environmental Health Association 1979 Kaplan 1991 Franceys Pickford amp Reed 1992 8 SANITATION 125 8 10 5 Potential problems the soakaway overflows th
22. 1 2 Wastewater coming from kitchens and bathrooms is termed sullage or grey water Sewage or black water includes sullage and human excreta from waterborne facili ties Sewage is called sludge when it becomes a thick mud In areas of high population density wastewater can pose a serious public health threat such as when it surfaces dur ing flooding or when there is no proper drainage Not only would it cause foul odours but it would also be a source of pathogens If sewer pipes break or if wastewater stagnates because the soil absorbs poorly the wastewater could seep into the drinking water supply and contaminate it The problems associated with waterborne waste disposal are the high water consump tion the sewer system often becomes blocked and the high capital and O amp M costs Some O amp M considerations associated with four options for dealing with a full pit latrine are shown in Table 8 1 Disposal options are considered in Table 8 2 Dry sanitation systems for excreta disposal One dry sanitation method is to dehydrate the human faeces Special collection devices which divert urine into a separate container for storage allow faeces to be dehydrated fairly easily The urine can be used directly as a fertilizer since urine contains most of the nutrients and the risks from pathogens are relatively low The classic example of an eco logical sanitation system based on dehydration is the Vietnamese double vault t
23. E WITH OPERATION AND MAINTENANCE 116 perform these tasks themselves If these tasks are carried out by the private often infor mal sector the labourers should also be educated in the concept of the system and its O amp M requirements 8 6 3 Actors and their roles Actors Roles Skills required User Use the latrine flush it keep it clean and inspect it and perform small repairs Sanitation worker Use the latrine flush it keep it clean and inspect it and perform KM small repairs Local mason Build and repair latrines KK Health department Monitor latrines and the hygienic behaviour of users train users KM MK in hygienic behaviour Simple often requires gender specific awareness raising and training activities to change behaviour and build capacity K Technical skills 4 4 Highly qualified 8 6 4 O amp M technical requirements Activity and frequency Materials and spare parts Tools and equipment Daily clean the squatting pan or seat Water soap Brush water container and shelter Monthly inspect the floor squatting pan or seat and U trap for cracks inspect the diversion box for blockage Occasionally unblock the U trap PVC pipes or Water Flexible stick or other flexible tools diversion box repair the squatting pan or seat U trap or shelter Cement sand water nails local building materials Bucket or bowl trowel
24. ags etc should not be thrown in the pit as they reduce the effective volume of the pit and hinder mechanical emptying Monthly maintenance includes checking the slab for cracks check ing the superstructure for structural damage ensuring that the lid remains tight fitting and ensuring that the surface water continues to drain away from the latrine Before the latrine becomes full a decision must be made as to the location of a new pit Time must be allowed for digging the new pit and transferring the slab and superstructure to it The contents of the old pit must then be covered with at least 0 5 m of top soil to hygienically seal it off In emergencies sanitation programmes tend to be more top down oriented and us ers are instructed on how to build their latrines or the latrines are built for them In most emergency situations people have ample time and opportunity and are very moti vated to be involved but strict hygiene control is essential Often several families use the same latrine and a caretaker or responsible committee should be appointed to organize cleaning and maintenance and to motivate proper use 1 Wegelin Schuringa 1991 Franceys Pickford amp Reed 1992 LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 114 8 5 3 Actors and their roles Actors Roles Skills required User Use latrine close lid keep latrine clean Caretaker or latrine Clean latrine motivate proper use perform small
25. ank is manoeuvred next to the dug hole in its discharge position The sludge is then discharged into the hole by opening a pressure release valve After putting the tank back in its original position it can be used to pump sludge again This routine is repeated until the required amount of sludge has been taken out of the pit The equipment is then cleaned and returned to the neigh bourhood parking place Minor repairs such as spot welding loose parts and repairing tyre punctures are carried out in small workshops in the area where the MAPET team operates and are paid for by the team Costs reach a maximum of US 25 per month Larger repairs and special maintenance mainly involve repairing or replacing bearings valves and guides 1 Muller amp Rijnsburger 1994 8 SANITATION 1253 replacing the piston leather once a year and replacing the tyres The jobs are done by trained mechanics in a specialized workshop Although the service can be provided privately it is more normal for the service to be provided by the local sewerage departments The responsibilities of a sewerage depart ment include training and licensing the pit emptiers manufacturing the MAPET equipment and providing the specialized maintenance for it monitoring the team s performance and making adjustments in the event of poor functioning particularly when it concerns public health 8 9 3 Actors and their roles Actors Roles Skills requir
26. ans outfow ported excavation costs are cheaper be cause the pipes can be laid at shal low depths the sewage flow rates in small bore pipes do not have to be self cleans ing rates material costs are lower because the pipe diameter can be small peak flow is reduced by the in terceptor tanks and there is no need for large manholes Figure 8 12 Small bore sewerage system there are fewer treatment require ments because the solids are kept in interceptor tanks The small bore sewer system consists of house connections an interceptor tank sewers cleanouts manholes vents a sewage treatment plant and lift stations where gravity flow is not possible The system is most appropriate for areas that already have septic tanks but where the soil cannot or can no longer absorb the effluent or where the population is too dense and there is no room for soakaways Small bore sewerage systems also provide an eco nomical way of upgrading existing sanitation facilities to a level more comparable to conventional sewers Initial cost No recent data were available but the cost of the system in Brotas Brazil was estimated to be 78 cheaper than conventional sewerage in Australia and USA the savings on construction costs were 25 35 but this excluded the cost of the interceptor tanks Area of use In areas where individual soakaways are not appropriate due to soil condi tions or
27. bear the higher costs cultural resistance against handling human waste may prevent households from emptying their own pit latrines but usually local labour can be hired to do the job 8 SANITATION 8 4 8 4 1 8 4 2 111 Double vault compost latrine The technology The double vault compost latrine con sists of two vaults watertight chambers to collect the faeces Urine is collected T separately because the contents of the vault should be kept relatively dry Ini tially a layer of absorbent organic mate rial is put in the vault and after each use the faeces are covered with ash or saw dust shredded leaves or vegetable mat ter to reduce smells and soak up SS SENSES excessive moisture The organic material NJE also ensures that sufficient nitrogen is earth retained in the compost to make it good compost fertilizer When the first vault is three quarters full it is completely filled with sana dry powdered earth and sealed and the oe contents allowed to decompose anaero bically The second vault is then used and Figure 8 4 Double vault compost latrine when it is three quarters full the first Straw vault can be emptied even by hand and the contents used as fertilizer The vaults should be large enough to keep the faeces long enough for them to become pathogen free at least two years A superstructure is built over both vaults and ea
28. ch has a squat hole that can be sealed off The latrine can be built anywhere since the vaults are watertight and there is no risk of polluting the surroundings Where there is rock or a high water table the vaults can be placed above ground A ventilation pipe keeps the aerobic system ac tive which is essential for composting Double vault latrines have been successfully used in Vietnam and Central America El Salvador Guatemala Honduras Nicaragua Main O amp M activities Initially some absorbent organic material is put into the empty vault layer of ashes or lime to ensure that liquids are absorbed and to prevent the faeces from sticking to the floor After each use or whenever available wood ash and organic material are added When urine is collected separately it is often diluted with 3 6 parts of water and used as a fertilizer Water used for cleaning should not be allowed to go into the latrine as it will make the contents too wet When the vault is three quarters full the contents are lev elled with a stick the vault is filled to the top with dry powdered earth and the squat hole is sealed The second vault is then emptied with a spade and bucket after which the vault it is ready for use The contents dug out of the second vault can be safely used as ferti lizer To help keep down the number of flies and other insects insect repelling plants such as citronella could be grown around the latrine Potential users of a vault latr
29. ck the delivery pipe Diversion boxes should be cleaned from time to time based on experience from operating the system Plant growth should be controlled to prevent roots from entering the pipes or trenches Minor O amp M and book keeping may be organ National Environmental Health Association 1979 Kaplan 1991 Franceys Pickford amp Reed 1992 LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 126 ized and carried out by households groups of households or the community organiza tion The responsible government department needs to monitor the performance of drainage fields and train users organizations artisans and caretakers on the technical aspects of their O amp M 8 11 3 Actors and their roles Actors Roles Skills required Householder user Check the outflow tank and performance of the drainage field and K or local caretaker control plant growth Local artisan Repair broken parts remove obstructions in delivery pipes KM Agency Monitor system performance train users caretakers and local artisans KKK in the use of the system provide assistance with major problems Basic skills 44 Technical skills 4 Highly qualified 8 11 4 O amp M technical requirements Activity and frequency Materials and spare parts Tools and equipment Regularly control plant growth Shovel bucket machete etc Every month clean the diversion boxes Water Shovel brush
30. down the drop pipe daily to maintain the water seal and to clear scum from the bottom of the drop pipe in which flies may breed Adding some sludge to a new tank will ensure the presence of microorganisms and enhance the anaerobic digestion of the excreta Routine inspection is necessary to check whether desludging is needed and to ensure that there are no blockages at the inlet or outlet The tank should be emptied when solids occupy between one half and two thirds of the total depth between the water level and the bottom of the tank Organizational aspects involve providing reliable services for emptying the tanks ensuring that skilled contractors are available for construction and repairs and controlling sludge disposal 8 7 5 Actors and their roles Actors Roles Skills required User Flush the toilet keep it clean inspect vents control contents of K the tank contact municipality or other organization for emptying when necessary and record dates tank was emptied Sanitation service Empty the tank control tank and vents repair if needed KM Agency Monitor the performance of the tank and the teams that empty it KKK train the teams Basic skills 56 Technical skills 3 Highly qualified 8 7 4 O amp M technical requirements Activity and frequency Materials and spare parts Tools andequipment Daily clean the squatting pan or seat Water Brush water container and shelter Monthl
31. ecome choked and they must be unblocked immediately using scoops and long sticks When full single pits should be abandoned and covered with at least 0 5 m of soil and a new pit dug If they are not to be abandoned they should be emptied by mechani cal means A pit can only be emptied manually if the excreta have been left to decom pose for at least 12 18 months In this time the excreta will have decomposed into harmless humus which makes a good fertilizer In a double pit system users should regu larly monitor the level of the pit contents If one pit is almost full the second pit should be emptied Again this can safely be done by hand but only if the pit to be emptied has been properly closed for at least 12 18 months The pipe leading to the full pit should then be sealed and the flow diverted to the emptied pit If latrines are used by a single household O amp M tasks are carried out by the house hold itself or by hired labour If several households use the latrine arrangements should be made to rotate cleaning tasks among the households The users need to understand the concept of the system fully to be able to operate it properly User education must include the reasons for using one pit at a time the need to leave a full pit for about two years before emptying and the use of excreta as manure The users also need to know how to switch from one pit to another and how to empty a pit even if they do not LINKING TECHNOLOGY CHOIC
32. ed Latrine user owner Contact the MAPET team negotiate the number of tank loads to be x removed negotiate the cost MAPET team Empty the pits stay in contact and negotiate with users organize SKM carry out and pay for minor maintenance and contact the workshop when major repairs are needed Mechanic Carry out the more specialized repairs and maintenance of the KM equipment Sewerage Monitor performance of the MAPET team train the pit emptiers and KKK department mechanics organize transportation and maintain equipment Basic skills Technical skills 4 Highly qualified 8 9 4 O amp M technical requirements for MAPET Activity and frequency Materials and spare parts Tools and equipment Regularly minor repairs such as tyre Rubber glue welding rods spokes Basic bicycle repair equipment punctures or small welding jobs basic welding equipment bucket Occasionally repair or replace handpump parts Timber gas pipe water valves Basic mechanical workshop tools repair the wheels Bearings tyres Basic mechanical workshop tools Annually replace the leather cup in the Leather cup Basic mechanical workshop tools handpump 8 9 5 Potential problems flat tyres broken metal parts that require welding wheel bearings that wear out rapidly a damaged wheel worn out pump elements bearings valves pistons a corroded tank the system is not suitable if t
33. ell designed constructed and operated septic tank additives such as yeast bacteria and enzymes which are often sold for digesting scum and sludge and for avoiding expensive pumping are not effective 8 8 Vacuum tanker 8 8 1 The technology A vacuum tanker is a motor vehicle equipped with a vacuum pump and tank for emptying or desludging pit latrines v septic tanks or sewers and for hauling sludge to a disposal station Conven tional vacuum tankers built on a regu lar 10 ton truck chassis have a hauling capacity of 4 6 m of sludge and mini tankers on a small chassis less than 2 m All vacuum tanker systems use a pump to create a vacuum in the tank and suction hose The vacuum then lifts the sludge into the tanker If the bottom lay Figure 8 8 Vacuum tanker ers of sludge are compacted they can be broken up with a long spade or jetted with a water hose before being pumped out Water hoses with their own water tanks are often fitted to the tankers Some tankers have high powered vacuum pumps and an air stream into the suction hose that acts as a transport medium for the sludge air drag or plug and drag techniques These tank ers can deal with heavy sludge in pit latrines especially at the bottom where solids have settled out and organic material has broken down A small amount of sludge should always be left in the pit to ensu
34. ems usual vehicle problems the main problems are not primarily due to technical failures but more to the lack of preventive maintenance not replacing spare parts and to the bad state of the roads the final disposal of sludge is often not supervised adequately tankers are not suitable for narrow streets steep slopes or wherever large vehicles cannot reach the tank or pit many tankers cannot handle the heavy sludge often found in dry latrines LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 122 8 9 8 9 1 8 9 2 Manual pit emptying technology MAPET The technology The Manual Pit Emptying Technology MAPET uses manually operated equip x ment to empty the latrine pit Its main components are a piston handpump and a 200 litre vacuum tank both mounted on pushcarts and connected by a 3 4 inch 2 cm hosepipe A 4inch 10 cm hosepipe is used to drain the sludge from the pit When the handpump wheel is rotated air is sucked out of the vacuum tank which sucks sludge from the pit through the 4inch hosepipe and into the tank The effective pumping head is 3 m depending on the viscosity of the sludge The sludge is usually bur Figure 8 9 MAPET system ied in a hole close to the pit or taken to a nearby disposal point e g a disposal field or sludge transfer station The equipment is small and hand operated and is therefore particularly suitable for high
35. from the latrine When the contents of the pit are 0 5 m below the slab a new pit should be dug and the old one covered with soil Alternatively the pit could be emptied mechani cally Where latrines are used by a single household O amp M tasks are implemented by the household or by hired labour If several households use the latrine arrangements have to be made to rotate the cleaning tasks to avoid social conflicts If pits are not emptied mechanically they can be emptied manually but only after their contents have been left to decompose for about two years Otherwise new pits must be dug when a pit is full If double pit latrines are used the users need to understand the concept of the system fully to operate it properly User education has to cover topics such as the reasons for using only one pit until the time for switch over the use of excreta as manure and the need to leave the full pit for about two years before emptying The users must also know how to switch pits and how to empty them even if they do not do these tasks themselves If these tasks are carried out by the private informal sector the workers have to be educated about the system and its operational requirements 8 3 3 Actors and their roles Actors Roles Skills required User Keep the latrine clean inspect and perform small repairs empty the full pit and switch to the new one dig a new pit and replace the latrine Local unskilled Dig pit
36. he sludge has to be transported more than 0 5 km to the burying site or transfer station transfer stations are only feasible if the municipalities facilitate the secondary col lection and treatment of the sludge potential demand for MAPET service is high but the system needs to be marketed more aggressively LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 124 8 10 8 10 1 8 10 2 Soakaway The technology A soakaway is a pit for collecting the liq uid effluent from a septic tank which is then allowed to infiltrate the ground The capacity of the pit should be at least equal to that of the septic tank The pit may be filled with stones broken bricks etc in which case no lining is needed or it may be lined with open jointed masonry often with a filling of sand or gravel between the lining and the soil to improve infiltration The top 0 5 m of the pit should be lined solidly to pro vide firm support for the reinforced con crete cover The cover is sometimes buried by 0 2 0 3 m of soil to keep in Lining Porous lining Figure 8 10 Soakaway sects out of the pit The size of the soakaway is determined mainly by the volume of liquid effluents produced and by local soil conditions With large effluent flows drainage trenches may be more economical than soakaways Planting trees adjacent to or over a soakaway can improve both transpiration and permeability Area of
37. hey should be made aware of the importance of maintaining the technol ogy in good working order and of the consequences should the technology malfunc tion The most common problems with dry sanitation are m The faeces become wet gt 25 humidity and therefore smells persist flies breed and pathogens survive This could be caused by leaking urine conduits or blocked vent pipes or poor maintenance of the system Absorbents like ash lime sawdust husks crushed dry leaves peat moss and dry soil are used to absorb excess mois 8 SANITATION 8 2 8 2 1 8 2 2 105 ture as well as to reduce smells and make the pile less compact Ventilation also helps to dry the contents and also removes smells allows flies to escape and in the case of composting toilets provides oxygen for the decomposition process E Cleaning material is used inappropriately after defecation Improved traditional pit latrine The technology Traditional latrines usually consist of a single pit covered by a slab with a drop hole and a superstructure The slab may v be made of wood sometimes covered y with mud or reinforced concrete The superstructure provides shelter and pri vacy for the user Basic improvements include Cover slab floor a hygienic self draining floor made ofsmooth durable material AANA IN Am and with raised foot rests ES a tight fitting lid that covers the drop hole to reduce smells and
38. illed up This alternating cycle can be repeated indefinitely Initial cost A single pit VIP family latrine costs US 70 400 while the double pit VIP version costs US 200 600 These costs include materials 60 80 transportation 5 30 and local labour 10 25 Actual costs will depend on the pit volume the quality of the lining slab and superstructure whether materials are available locally and local prices Area of use Household and community level in rural and periurban areas 1 Sources Smet et al 1988 Wegelin Schuringa 1991 Franceys Pickford amp Reed 1992 8 SANITATION 109 8 3 2 Main O amp M activities Operation of pit latrines is quite simple and consists of regularly cleaning the slab with water and disinfectant to remove any excreta and urine The door must always be closed so that the superstructure remains dark inside The drop hole should never be covered as this would impede the airflow Appropriate anal cleaning materials should be avail able for the latrine users Nonbiodegradable materials such as stones glass plastic rags etc should not be thrown into the pit as they reduce the effective volume of the pit and hinder mechanical emptying Every month the floor slab should be checked for cracks and the vent pipe and fly screen inspected for corrosion or damage and repaired if necessary The superstructure may also need to be repaired especially light leaks Rainwater should drain away
39. ine technology should be consulted extensively to find out if the system is culturally acceptable and if they are motivated and capable of operat ing and maintaining the system properly The project agency will need to provide sus tained support to ensure that users understand the system and operate it properly 1 Winblad amp Kilama 1985 Franceys Pickford amp Reed 1992 LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 112 8 4 3 Actors and their roles Actors Roles Skills required User household Use latrine remove urine help keep latrine clean inspect and perform small repairs help to empty the pit and switch over to the new pit Local mason Build and repair latrines KK Local pit emptier Empty the pit and switch over to the new pit check the system SKM and perform small repairs External support Investigate whether the double vault technology is appropriate SKM MK organization monitor users O amp M and hygienic behaviour and provide feedback train users and local artisans Simple often requires gender specific awareness raising and training activities to change behaviour and build capacity K Technical skills 4 Highly qualified 8 4 4 O amp M technical requirements Activity and frequency Materials and spare parts Tools and equipment Daily clean the toilet and superstructure Water lime ashes Brush water container empty the urine collection pot
40. is is a particular problem if both toilet wastes and sul lage are collected in the septic tank and the tank was designed for toilet wastes only the system not suitable if there is not enough space or water or sufficient financial resources for construction where the soil is not permeable enough or is too hard to dig out bedrock or where the groundwater is close to the surface 8 11 Drainage field 8 11 1 The technology Drainage fields consist of gravel filled Future diversion box underground trenches called leachlines or drainage trenches that allow the liquid effluent from a septic tank to in filtrate the ground Open jointed stone overflows in A A undisturbed earth ware or perforated PVC pipes lead the beep a e y liquid effluent into the drainage field Future replacement trenches Initially infiltration may be fast but af p4 i Overflow line Section A A ter several years the soil clogs and an e Backfill equilibrium infiltration rate is reached TO Silt barier ajar ne ne Bs et If the sewage flow exceeds the equilib rium rate of the soil sewage will eventu x af le rg ally surface over the drainage field pa aay i Pressure can be taken off drainage fields Ec RR by reducing the amount of water and l E solids flowing into the solids interceptor tank e g by installing toilets that use less Figure 8 11 Drainage field water
41. ll a decision must be made as to the location of a new pit Time must be allowed for digging the new pit and transferring the slab and superstructure to it The contents of the old pit must then be covered with at least 0 5 m of top soil to hygienically seal it off When latrines are used by a single household O amp M tasks are implemented by the household or by hired labour If several households use the latrine arrangements for rotating the cleaning tasks have to be made to avoid social conflict Pits can only be emptied manually if their contents have been left to decompose for about two years Otherwise when a pit is full it must be emptied mechanically or a new pit has to be dug 8 2 3 Actors and their roles Actors Roles Skills required User Use the latrine close the lid keep the latrine clean inspect the latrine and perform small repairs on it User or local labour Dig a new pit shift or transfer the slab and superstructure Local mason Build and repair the latrine SKK Health department Monitor latrines and hygienic behaviour of users and train users KKK in hygienic behaviour Simple often requires gender specific awareness raising and training activities to change behaviour and build capacity K Technical skills Highly qualified 8 2 4 O amp M technical requirements Activity and frequency Materials and spare parts Tools and equipment Daily clean the drop hole
42. llow tank that allows drainage and is covered with a layer of sand The sludge is then lifted after about one week Solid liquid separation Solids are separated from the liquid wastes by sedimentation or rough filtering The solids are then lifted Anaerobic digestion Sludge from the latrine is added to wastewater sludge and separated by sedimentation at wastewater treatment plants Extended aeration The sludge is aerated O amp M is expensive Sewerage system Sludge is discharged into wastewater treatment plants The rate of discharge is impor tant for this method to work properly Waste stabilization ponds The sludge is treated in waste stabilization ponds either with municipal wastewater or separately a Adapted from Pickford amp Shaw 1997 8 SANITATION 107 addition appropriate anal cleansing materials should be available in or near the latrine Ash or sawdust can be sprinkled into the pit to reduce the smell and insect breeding Nonbiodegradable materials such as stones glass plastic rags etc should not be thrown into the pit as they reduce the effective volume of the pit and hinder mechanical empty ing Monthly maintenance includes checking the slab for cracks checking the superstruc ture for structural damage ensuring that the lid remains tight fitting and ensuring that the surface water continues to drain away from the latrine Before the pit latrine be comes fu
43. lls and the soil should be adequately perme able for infiltration The concrete floor slab with the pan is either on top of the leaching pit direct system or a short distance from one pit single offset or two pits double offset In offset systems a short length of PVC tubing slopes down from the U trap to the pit or in case of a double pit system to a diversion box which diverts the flush into one of the two pits The double offset system enables the two pits to be used alternately When the first pit is full it should be left for at least 12 18 months to allow time for the patho gens to be destroyed After this time the contents of the first pit can be safely removed even by hand and used as organic fertilizer The first pit is then ready to be used when the second pit fills up Double offset pits are usually smaller than single pits because they need to last for only 12 18 months Pour flush latrines are most suitable where people 1 Winblad amp Kilama 1985 Wegelin Schuringa 1991 1993 Bakhteari amp Wegelin Schuringa 1992 Franceys Pickford amp Reed 1992 van de Korput amp Langendijk 1993 8 SANITATION 8 6 2 115 use water for anal cleansing and squat to defecate but they are also popular in countries where other cleansing materi iP als are common Pour flush latrines may be upgraded to a septic tank with a drain age field or soakaway or may be con nected to a small bore sewerage system
44. low flush toilets or by prevent ing sullage from entering the tank The drainage trenches are usually 0 3 0 5 m wide and 0 6 1 0 m deep from the top of the pipes The trenches are laid with a 0 2 0 3 gradient of gravel 20 50 mm diam eter and a 0 3 0 5 m layer of soil on top A barrier of straw or building paper prevents the soil from washing down The trenches should be laid in series so that as each trench fills it overflows to the next one This ensures that each trench is used either fully or not at all The trenches should be 2 m apart or twice the trench depth if this is greater than 1 m The bottom of a trench should be at least 0 5 1 m above groundwater bedrock or impermeable soil and the slope of the land should not exceed 10 An area of land equal in size to the drainage field should be kept in reserve either to allow the field to be extended in the future or to allow another drainage field to be dug if the first becomes clogged Drainage fields are often used instead of soakaways where larger quantities of liquid effluent are produced 8 11 2 Main O amp M activities Hardly any activities are required to operate the system except to watch for field over flows switching to a second drainage field every 6 12 months and determining the dates of switching if applicable The tank outflow should be cleaned and checked that it is in good working order if not it should repaired Sometimes it may be necessary to un blo
45. oilet In Northern Vietnam a common practice was to fertilize rice fields with fresh excreta To combat this hazardous practice in 1956 the health authorities started campaigns to con struct double vault dry latrines and followed this up with health education programmes It is now widely used in Vietnam and to some extent in Central America Mexico and Sweden A second dry sanitation method is to compost the human faeces This involves a bio logical process in which bacteria and worms break down the organic material under controlled conditions e g temperature moisture and airflow and make humus If the composting conditions are properly controlled the humus is free of human pathogens and is an excellent soil conditioner A drawback of this method is that in many develop ing countries it is likely that the composting conditions would not be controlled prop erly which could lead to humus contaminated with pathogens The health aspects of dry sanitation systems either by dehydration or composting are not well understood yet and these technologies cannot be recommended without a clear understanding of how they function especially where O amp M are unlikely to be ad equate In addition the most unfamiliar aspect of dry sanitation is that it requires some handling of human faeces at household level which for many is still taboo and may involve health risks Nevertheless if communities wish to consider ecological sanitation technologies t
46. re that decomposition continues rapidly Vacuum tankers can be emptied by pressure discharge or by tipping the tank Initial cost the cost of a vacuum tanker can vary enormously and depends on the manu facturer the condition of the equipment the country of use etc Prices can vary from US 20 000 100 000 or more Area of use Urban or periurban areas with roads conventional system or with reason able access for mini tankers 1 Boesch amp Schertenleib 1985 LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 120 8 8 2 Main O amp M activities Daily checks before work the oil levels in the vacuum pump oil cooling tank hydraulic tank and tanker engine the tanker fuel level the water levels in the tanker engine the windscreen water bottle the wash tank and the water tank for the vacuum pump are all the necessary materials present the cooling radiator for the hydraulic oil and pump oil is the rear door closed and secured Daily operation after work drain the sludge and oil separators Weekly checks tyre pressures lights indicators horns valves that prevent the tank from being overfilled contacts between gaskets and seats and performance steel balls leaks in the hydraulic system tighten couplings and power take off shafts de pending on type Two yearly check vacuum pump bearings after 3000 hours or two years Chassis and engine
47. s transfer structures empty full pits in double pit systems KK labour sweepers perform small repairs solve small problems scavengers Local mason Build repair and transfer latrines KM Health department Monitor latrines and the hygienic behaviour of users educate users SKM MK in good hygiene practices Simple often requires gender specific awareness raising and training activities to change behaviour and build capacity KK Technical skills 4 4 Highly qualified LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE 110 8 3 4 O amp M technical requirements Activity and frequency Materials and spare parts Tools and equipment Daily clean the drop hole seat and Water soap Brush bucket superstructure Monthly inspect the floor slab and fly screen vent pipe Every 1 6 months clean the fly screen and the inside Water A twig or long flexible brush of the vent Occasionally repair the slab seat vent pipe fly Cement sand water nails local Bucket or bowl trowel saw screen or superstructure building materials hammer knife Depending on size and number of users dig anew pit and transfer latrine Sand possibly cement bricks nails Shovels picks buckets hammer slab and superstructure if and other local building materials saw etc applicable switch to the new pit when the old pit is full Shovels
48. the organization responsible for commu nal sewer maintenance This organization should also bear responsibility for treating liquids from the sewers 8 12 3 Actors and their roles Actors Roles Skills required Householder Check household plant and equipment and help the community K organization inspect the tanks and common sewer line Local labour Check on site plant and equipment perform small repairs and SKM mechanic remove blockages in the sewer pipes Community Organize the regular checking of the community sewer notify the K organization agency of problems that cannot be solved and collect sewer charges Agency Monitor the system s performance keep regular contacts with KKK community organizations and monitor their performance train teams and mechanics organize staff and community members operate and maintain the collector sewer pumping station and treatment plant Basic skills 44 Technical skills 444 Highly qualified 8 12 4 O amp M technical requirements Activity and frequency Materials and spare parts Tools and equipment Daily weekly clean the grease trap Specialized tools and equipment Regularly inspect the street sewers Specialized spare parts and materials Specialized tools and equipment At least annually check the inspection chambers plant and equipment pumps controls vacuum chamber surge chamber and valves
49. uce two problems fre quently encountered with traditional la trine systems bad odours and insect proliferation A VIP latrine differs from a traditional latrine by having a vent pipe that is covered with a fly screen Wind blowing across the top of the vent pipe creates a flow of air which draws out odours from the pit As a result fresh Cover ele air is drawn into the pit through the drop Pow xe hole and the superstructure is kept free of smells The vent pipe also has an im portant role to play in fly control Flies are attracted by light and if the latrine is Porous lining suitably dark inside they will fly up the vent pipe towards the outside light where they are trapped by the fly screen Figure 8 3 Ventilated improved pit latrine and die of dehydration Female flies searching for an egg laying site are attracted by the odours from the vent pipe but are prevented from flying down the pipe by the fly screen at its top VIP latrines can also be constructed with a double pit The latrine has two shallow pits each with its own vent pipe but only one superstructure The cover slab has two drop holes one over each pit but only one pit is used at a time When one becomes full the drop hole is covered and the second pit is used After about two years the contents of the first pit can be removed safely and used as soil condi tioner The first pit can be used again when the second pit has f
50. y inspect the floor squatting pan or seat and U trap Regularly ensure that the entry pipe is still Water Stick submerged for aqua privies Occasionally unblock the U trap Water Flexible brush or other flexible material repair the squatting pan or seat Cement sand water nails local Bucket or bowl trowel saw U trap or shelter building materials hammer knife Annually control the vents Rope or wire screen materials Scissors or wire cutting tool pliers pipe parts saw Every one to five years empty the tank Water fuel lubricants etc Vacuum tanker large or mini or MAPET equipment 8 SANITATION 119 8 7 5 Potential problems many problems arise because inadequate consideration is given to liquid effluent disposal large excreta flows entering the tank may disturb solids that have already settled and temporarily increase the concentration of suspended solids in the effluent if the water seal is not maintained in an aqua privy the tanks will leak and cause insect and odour problems this system is not suitable for areas where water is scarce where there are insuffi cient financial resources to construct the system or where safe tank emptying can not be carried out or afforded if there is not enough space for soakaways or drainage fields small bore sewers should be installed aqua privies only function properly when they are w
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