From the Roof to the Cup: Harvesting Rainwater in a Masai Community School in Kenya

Transcription

1 Night Bank Initiative Outline From the Roof to the Cup: Harvesting Rainwater in a Masai Community School in Kenya 12 September 2017

2 From the Roof to the Cup: Harvesting Rainwater in a Masai Community School in Kenya Duration of Implementation 2 months Area / Village / City Olare Olok Region / state Narok County Country Kenya Summary The population of Olare Olok currently consumes unsafe polluted water directly from the Talek river or temporary unprotected springs which dry out in the dry season. Children are particularly hit by water-related diseases such as typhoid fever, hepatitis A and diarrhoea which can be easily prevented with access to safe water, sanitation and improved hygiene practices. The initiative aims to provide access to safe drinking water for the 325 students of Olare Olok school by building a rainwater harvest system. Budget 12 September ,497 euros are needed to build a water tank on the school roof to provide fresh water to the school children, teachers and other community members.

3 Target Group Environment The initiative will directly provide all-year round access to safe drinking water to the 325 students of Olare Olok school aged 5 to 13 and the 9 school staff. The surplus of water harvested during the rainy season months will also provide a safe and more accessible source of drinking water for the whole population Olare Olok area estimated to 1,000 people (170 households). Cattle and sheep herding are the principal livelihood of this predominantly Masai community, increasingly threatened by erratic rainfall patterns and pressure over scarce natural resources. Some individuals are employed in the safari tourism sector in the area or benefit from tourism-related income generating activities such as handcrafting. Located in the Talek river sub-basin, very close to the border of the Masai Mara Reserve and the Olare Motorogi Conservancy, Olare Olok area belongs to the larger Serengeti-Mara ecosystem, rich in biodiversity and the iconic savanna wildlife. The Masai community customs, lifestyle and livelihoods are intrinsically connected to the natural environment. Wildlife, domestic animals and humans coexist in Olare Olok area. Testimonies of the people living in this area recount for increasingly unpredictable rainfall patterns, lower precipitation, increased temperatures and longer dry seasons. They attribute this to the effect of climate change, which they say is directly impacting on the availability of water resources for human uses and to maintain ecosystems healthy. Climate variability, along with population growth and economic activity development such as tourism and livestock production, are threatening the equilibrium of the ecosystem and thus impacting negatively on biodiversity and Masai livelihoods. The initiative will contribute to build communities resilience to drought, lessen the abstraction of surface water resources and limit the risks of direct human contact with wildlife during water collection trips to the river, ponds and natural springs.

4 Description of the Initiative 1. Current problem and effects The communities living in the Talek river sub-basin in Narok County are affected by water scarcity as well as poor water quality. In some areas groundwater is naturally very saline, creating problems such as skeletal and dental fluorosis when used for drinking purposes. The rural areas in the Talek river sub-basin have witnessed little development in water supply infrastructure. According to the report Exploring Kenya Inequality, Narok County has the poorest access of all the counties in Kenya, with only 20.1% of the population having access to improved water sources, the majority of them in the urban areas of the county. (p , KNBS and SID, 2013) Link Olare Olok is a cluster of settlements with an estimated population of 1,000 individuals who have no access to any source of water safe for human consumption. The school does not have any safe water facility either. The community relies on the daily collection of water directly from the Talek river, ponds and unprotected seasonal springs. Women and older girls, who take the responsibility of water collection in the community, carry on their backs an average of 20 litres in walking round trips of 30 to 45 minutes. Besides the physical burden and the time invested per day for water fetching, women and children are also exposed to the risk of wildlife attacks, particularly in the areas close to the water points which are also gathering places for wildlife. During the 5 months of the dry season, from June to October, the natural spring dries out. The river flow severely decreases and due to high evaporation rates, it dries up completely in some areas. The only water resources available during the dry months are stagnant ponds of water scattered along the river basin which are highly contaminated with organic matter as well as bacteria and virus from wildlife excrements and decomposing animal bodies. Competition over the shallow surviving water ponds also increases risks of attacks from hippos, crocodiles and other animals. The consumption of unsafe polluted water without appropriate treatment (filtration and disinfection) results in the exposure to life-threatening diseases, which are aggravated by poor access to distant health services. The community experiences frequent cases of typhoid, hepatitis A and diarrhoea. All of them are water related diseases affecting children most severely. Children are more vulnerable to infection and death if not treated quickly and adequately. The spread of these diseases can be easily prevented with access to sufficient and safe water supply, sanitation and

5 Description (continued) improved hygiene. 2. The Initiative proposed Access to a safe and sufficient water supply is a priority concern for the Olare Olok community. Without any prospect of water supply development projects in the area by government or nongovernmental agencies, the community is willing to find quick and tangible solutions to tackle the problem. A few small projects of rainwater harvesting have been implemented in other villages of Narok County, but so far Olare Olok community has not received any support to develop the infrastructure that will allow them to use rainwater as a complementary source of safe water. Rainwater is considered a suitable low-cost solution by the community, particularly since groundwater is less exploitable due to high salinity and more expensive infrastructure requirements. Traditional housing or bomas with thatched roofing do not allow for rainwater harvesting at household level. However, the school building, with a sloping corrugated steel roof provides a very suitable catchment area of 785 m2 for rainwater harvesting. The Initiative aims to install the infrastructure required to collect rainwater runoff during the two rainy seasons from March to May and from November to December. Water collected in the tank will provide a safe source of drinking water all year round, bridging the gap between the two rainy seasons. This initiative aims to fund the complete design and installation of the rainwater harvest system which includes the following components: Durable gutter and pipes system to collect the roof rainwater runoff. Filter unit located before the entry to the storage tank to remove debris and solid particles in the rainwater runoff. Durable masonry storage water tank with a minimum total capacity of 55 m3. The tank is equipped with an overflow pipe, a drain pipe and an outlet pipe with a high-quality and durable tap. Drainage system to safely dispose excess water and avoid flooding, preventing damage to the storage tank and breeding of flies and mosquitoes. The project technical specifications at the end of this form can be consulted for further details. Operation and maintenance of the systems is easy and does not require specific technical skills. The school management staff, who will be in charge of running the system, will be trained on key maintenance activities to preserve the quality of the water supply such as:

6 Description (continued) Roof and gutters cleaning before the rains. Use of the first flush pipe to discard the first water collected from a rainstorm. Cleaning and replacement of the filter unit. Cleaning and maintenance of the tank. Water treatment options in case of water contamination. 3. Expected immediate results and longterm impacts As an immediate result of the installation of the rainwater harvest system the 325 children of Olare Olok school will gain direct access to a safe water supply within the school facility. An initial storage capacity of 55 m 3, will be able to provide at least 1 litre of safe drinking water per children per day during the 5 months of the dry season from June to October, which is the minimum volume required for full hydration in average conditions for children (p.7, WHO, 2003) Link The rest of the year, from November to May, the system has the potential to provide 4-5 litres per person per day. The excess safe water harvested during these rainy season months which is not consumed in the school will be taken home by the school students in small jerry cans, inverting the current situation whereby the students bring unsafe water from their households to drink in the school. This will result in an improvement in access to safe water for the entire members of the household, including children under 5 not attending school. The design of the system will also allow for a future scale-up of the system with a second tank m 3, thus providing 2 litres of drinking water per student during the 5 months of the dry season. The rainwater harvest system in the school will result in the following immediate positive changes in the community: Decrease in the prevalence of waterrelated diseases such as typhoid fever, hepatitis A and diarrhoea among children. Reduction of the number of trips to river, ponds and springs for water collection, limiting risks associated to direct contact with wildlife and alleviating water transport burden for women and older girls. Expected medium and long-term positive impacts of the initiative include: Overall children health condition and well-being is improved. Access to safe drinking water all year round improves children s physical and cognitive development and thus their performance in school.

7 Description (continued) School attendance is encouraged by the presence of a safe source of water. Girls school attendance and performance improves as the time spent for water collection is reduced, thus improving equality between boys and girls. Reduction in the number of water collection trips limits disturbance to wildlife and the risks of attacks, thus mitigating human/wildlife conflict. Reduced pressure and competition over scarce surface water sources. Potential of rainwater harvesting to build community resilience to drought and adapt to climate change is developed, favouring the scale-up of the system and replication of rainwater harvesting in neighbouring communities. No negative social, economic or environmental impacts have been identified.

8 Relavance Complementarity Human Right to Water and Sanitation (HRWS) was recognised as a human right by the United Nations (UN) General Assembly on 28 July 2010 and is recognized in international legal instruments. It provides for sufficient safe, acceptable, physically accessible and affordable water for personal and domestic uses and accessible sanitation facilities. Kenya s 2010 Constitution acknowledges access to clean and safe water as a basic human right. Despite positive overall progress made in the country in the last decades, there are still very significant inequalities within the country: 81.6% or the population in urban areas have access to improved water versus only 56.8% in rural areas (WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation, 2015). Link Narok county is far below the country average, with only 20.1% of the population having access to improved water sources in 2013, majority of them in the urban areas of the county (p , KNBS and SID, 2013). Rainwater harvesting is a suitable solution in this context because operation and maintenance is easy and low-cost, the water supply is safe for drinking if the system is well operated and maintained and it is a culturally acceptable option for Olare Olok community. Rainwater harvesting could be further developed in the area to provide sufficient amounts of safe water for the entire community population. This initiative represents a significant first step for Olare Olok community in their path to gain access to this basic right. The school rainwater harvest system proposed will alleviate the current water problems but alone it does not solve the problem of water availability for the entire community. Further complementary investments in water supply infrastructure are necessary to guarantee that all members of Olare Olok community have access to sufficient safe, acceptable, physically accessible and affordable water for personal and domestic uses.

9 Coverage Social Equity & Gender Equality Sustainability The initiative directly targets the totality of the children attending Olare Olok school. The rest of the community of Olare Olok will also benefit of the excess safe water harvested during the rainy season months. The school staff commit themselves to ensure that all the school children have equal access to the water facility, particularly during consumption restrictions in the dry season, avoiding discrimination of any kind (gender, tribe, disability, etc.). A reduction in the number of water collection trips is likely to improve girls school attendance and performance, thus reducing inequalities between boys and girls in access to education and opportunities. The rainwater harvest system is environmentally sustainable, it uses an unlimited and renewable source of water and no energy input is required. Rainwater is free and the operation of the system does not require any financial input, only regular voluntary labour work to keep the roof and the system clean to avoid water contamination. The school staff and community members are committed to the good functioning of the system and to ensure its regular maintenance, including financial contributions for future repairs of the tank or other components of the system. The materials proposed for the infrastructure have been selected for their durability, ex. galvanized steel gutters instead of PVC. The experience in similar projects and the quality of materials are key criteria in the selection of the engineering company in charge of the works. The system has an estimated lifespan of 30 years but can be much longer if its well-maintained and the community invests in its conservation.

10 Risks Risk of water contamination with pathogens (bacteria, virus, protozoa) during the 5 months of the dry season in which temperatures are high and the water in the tank is not renewed. Even in the event of some microbiological contamination, it is expected that the tank water will still be of better quality and represent less health risks than the water from river and ponds which is currently consumed untreated in Olare Olok community. Mitigation measures: The school staff will be trained on key operation and maintenance procedures to keep the water free from contamination: regular cleaning of roof and gutters, use of first flush diverter, regular cleaning and replacement of filter material and tank cleaning. The staff will also be trained on how to identify contamination and available water treatment options (boiling and chlorination). Risk of tank leakage or collapse. Mitigation measures: The construction works will be entrusted to reliable and licenced engineering companies able to propose high quality materials, suitable technical designs and proof of experience in similar projects. The lifespan and correct functioning of the system will be closely linked to the correct regular maintenance of the system as well the investment in future restorations such as leakage and cracks repair or renewal waterproof lining. The school staff and the community have committed to regularly maintain the system according to the engineer specifications and to financially contribute for the future conservation of the tank. Risk of severe drought resulting in insufficient water storage and unavailability of safe water in the school during the 5 months of the dry season. Mitigation measures: The system has potential to be upgraded with a second storage tank of similar dimensions. Further development of water supply infrastructure, including rainwater harvesting, will increase resilience to drought by increasing storage capacity and diversifying water resources.

11 Resources Available Resources Needed The initiator and the school management board will monitor the works of the engineering company on-site and the community will provide volunteering labour for non-skilled works as required. The community also counts with the voluntary support and advice from a development project manager with experience in rural water supply projects for the preparation, implementation and monitoring of the initiative. Night Bank support is required to fund the engineering works required to implement the rainwater harvest system in the school, including the installation of the gutter/pipes network and construction of the masonry 55 m3 water tank. The engineering company in charge of the works will be selected through independent evaluation of quotes and technical proposals from at least 6 suppliers. The suppliers are ranked against the following criteria: compliance with regulations, experience in similar projects, quality of technical design, quality of materials proposed and price.

12 Night Bank Initiative Outline Budget 12 September 2017

13

14 Night Bank Initiative Outline Technical Specifications 12 September 2017

15 1. SUPPLY AND DEMAND CALCULATIONS 1.1 Maximum supply Average annual precipitation Narok county, Kenya : 771 mm Annual distribution: source:climate-data.org source: sdwebx-worldbank 2

16 The pattern of precipitation is classically bimodal, with the long rains March to the end of May and the short rains October to December. The driest period runs from June to October (5 months) with another shorter dry period on January and February (2 months). The rain will be collected using the roof surface catchment area in the school: 132ft x 64 ft= 8448 ft sq / 40,23m x 19,50 m = 785m 2 The roof is made corrugated steel with no-lead paint and is in good condition. Estimated runoff coefficient for this material = 0.85 Considering possible leakages from gutters, water overshooting gutters and water lost in the first flush of poorer water quality, the runoff coefficient is decreased to 0.80 (80% of rainfall falling in the roof is expected to enter the tank). Total annual supply = 785m 2 x 0.80 x 771 mm = litres/year or 484 m 3 /year 1.2 Maximum demand The system aims to provide water for drinking purpose only for the 325 students in the school (+ 5 teachers/staff) Daily drinking water consumption in school = 2 litres/per capita/per day Annual drinking water demand = 2 litres x 330 students x 365 days = litres/year or 241 m 3 /year Remark: The calculation is based on 365 days, thus including school holiday periods as this will be a source of safe drinking water which is more accessible than other existing sources (temporary spring and river) which are further away and are less safe. Considering a coefficient of 10% for loses (cleaning the tanks, some small loses at taps ) the annual drinking water demand is estimated to: 265 m 3 Rainwater harvesting using the school roofing as catchment area is therefore a feasible option as the total annual amount of water available from the roof catchment (484 m 3 /year) is much larger than the total annual maximum demand for drinking purposes (265 m 3 /year) based on 2L/p/day for all students and staff in the school. The storage capacity of the tank will be the limiting factor to the harvesting of the maximum total annual amount of water available from the roof catchment. 1.3 Storage calculations Initial calculation of the storage volume required at the start of the dry season to supply water before the next rains start (maximum dry period of 5 months=153 days): Storage volume required: to provide 1 L/p/day = (1 litres x 330 students x 153 days) +10% = litres or 55 m 3 to provide 2 L/p/day = (2 litres x 330 students x 153 days) +10% = litres or 111 m 3 Ideally two or more tanks with a total storage capacity of 111m 3 would be necessary to ensure a minimum of 2 litres per day per person during the 153 days of the dry season. 3

17 For this first phase of the project the objective is to install one or several tanks with a total capacity of 55 m 3, able to provide at least 1 litre of safe water per person per day during the 5 months of the dry season and 4-5 litres per person per day during the rest of the year as shown in the table below. Annual variaton of rainfall captured and drinking water supply VOLUME (L) NOV (start) DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT Rainfall captured Rainfall captured Available water supply 4

18 2. SPECIFICATIONS FOR THE DESIGN OF THE RAINWATER HARVEST SYSTEM The design of the rainwater harvest system should observe the following criteria: - High quality and durability of the equipment used (including the gutters, pipes, tap, etc.) Specification of equipment guarantee. - Water tank design ensuring durability, impermeability, easy maintenance/cleaning and protection from water contamination. - Easy daily use, maintenance and cleaning by users (including children). - Consideration of locally available materials and labor force. - Good quality-cost relationship. Example showing main components of a basic roof catchment rainwater harvest system (Ken Chatterton WEDC Loughborough University) Note that the figure above is just for example of the different components. The information below provides measurements and specifications to consider in the preliminary technical design and quote. 5

19 Roof measurements: Plan view: 64ft (19,5m) 132 ft (40,23m) Height floor to roof =9ft (2,74m) Main components of the Material Dimensions/Location Quantity system: 1 Semi-circular gutters for Galvanized steel Roof length= +132ft (40,23m) 2 rainwater collection along the length of the roof and mount hardware, straps and brackets. Gutter diameter = 150 mm minimum 2 End-caps for the gutters Galvanized steel Diameter = gutter diameter 4 3 First flush diverter or First rain separator (vertical downpipes with cap/valve to dispose water from first flush) and fixation/mount hardware. 4 Main downpipe to collect runoff from both gutters and into the tank and fixation/mount hardware. 5 Filter unit above the point of discharge into the tank 6 Storage tank or tanks (*see specifications below) Galvanized steel Height floor to roof= 9ft (2,74m) 2 Galvanized steel Roof width = 64 ft (19,50 m) Option A : 1 downpipe collecting water from both gutters Option B: 2 downpipes, one for each gutter Coarse gravel and netlon mesh filter units Reinforced cement concrete (RCC) Number, dimension and composition of the filter to determine according to the maximum runoff flow rate Option A: 1 downpipe collecting water from both gutters and 1 filter unit Option B: 2 downpipes, one for each gutter and 2 filter units Water tight tank with total storage capacity of 55m 3 and foundation or base of 10-15cm height. Semi-buried base with 5 cm above ground. 7 Overflow pipe Galvanized steel At the top of the tank Minimum diameter 150mm With removable mesh 1 or 2 1 or

20 8 Drain pipe with valve Galvanized steel Located at the bottom of the tank 1 9 Outlet pipe with tap Galvanized steel Located 100mm above the bottom of the tank 10 Cement base and cement Cement/sand/grava Design to drain water from the drain drain channel to drainage pipe, overflow pipe and water spillage trench from outlet pipe and (7,8 and 9) 1 1 Specifications to consider in the technical design 1.Gutter and pipes system: 1.1 The gutter and pipes will be in good quality galvanized steel for longer durability. 1.2 Gutters should slope (approx 0,2% slope) in the direction of the storage tank and not away from it. 1.3 Gutters need to be supported so they do not sag or fall off when loaded with water. The way in which gutters are fixed will depend on the specific characteristics of the school building. 1.4 The gutters should have a diameter of at least 150mm and end caps to avoid water spillage. 1.5 The first rain separators or first flush pipes have a valve or an end cap to discard the first water collected from a rainstorm (propose cost of two options, valve or end cap). 1.6 The down pipes should be clamped firmly to the wall. 2.Filter unit: 2.1 A filter unit will be located before the entry to the storage tank to remove debris and solid particles in the rainwater runoff. 2.2 It is recommended to have 2 interchangeable mesh grids between the inlet pipe and the filter, to allow easy collection of leafs, insects, debris. They should be easy to remove, clean and fix again. 2.3 The proposed filter unit should have a filtration rate according to the maximum rainwater flow rate from the roof catchment area considering high intensity precipitation episodes to avoid water overflow in the filter if filtration rate is too slow. An alternative option can be to have 2 filter units, one for each gutter and downpipe into the tank, to reduce the water volume and flow rate and avoid overflow in the filter (see options A and B in table above). 2.4 The design options should include the dimensions, filter materials (Ex. grava size) and height of each filtration layer. 3.Storage infrastructure: 3.1 The total storage capacity required is 55m 3. Considering that the area surrounding the school is relatively flat and that the dimensions of the roof are 9ft height, 64ft width and 132ft length, the supplier can propose different tank designs. For long-term sustainability purposes, the storage tank is proposed to be built in reinforced cement concrete (RCC kg/m3 + anti-leakage additive type Sikatex). It is recommended that the tank has a foundation or base of 10-15cm height that could be semiburied in the ground. The supplier will provide in his offer a detail plan of the structure, measurements and material quantities for the technical design proposed. 3.2 The floor of the tank should slope gently towards the drain pipe and outlet pipe. The top of the tank will have a slight slope to avoid stagnant water at the top. 7

21 3.3 The tank will be water tight and completely closed, with a lockable metal manhole at the top of the tank to allow for cleaning. 3.4 A water tightness test will be conducted by the supplier after construction and before delivery. 3.5 The outside walls of the tank will be painted in white non-lead paint. 3.6 The overflow pipe (7) should be minimum 150 mm diameter and have a removable mesh at the bottom to prevent insects from coming in. 3.7 The drain pipe with valve (8) is located exactly at the bottom of the tank floor (sloping side), the offer should specify the size of outlet pipe proposed and the valve type. 3.8 The outlet pipe with a high-quality and durable tap (9) is located 10cm above the bottom of the tank floor (sloping side). The offer should specify the size of the outlet pipe proposed and the tap model. Drainage: 4.1 The offer should include in the design a drainage system to safely dispose water from the tank overflow, drainage water from tank cleaning and water loss from water collection at the tap. 4.2 It is recommended that the area just below the tap and drain valve is a cemented platform with a cement drain connected to a drainage trench that should have an appropriate design to avoid flooding around the tank and nuisance/breeding of flies/mosquitos. The dimensions of the drain proposed should be specified in the offer. Different device options can be proposed for the use of the drained water (animal drinking, irrigation, soak away (ground infiltration), etc). 8