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EWB-MN Kyetume, Uganda Critical Design Review

EWB-MN Kyetume, Uganda Critical Design Review. March 5, 2008. Introduction. Location – rural village 40 km south of Masaka, Uganda Community of 2000 where 19% of the children are orphans Partnership – Uganda Rural Fund

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EWB-MN Kyetume, Uganda Critical Design Review

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  1. EWB-MN Kyetume, Uganda Critical Design Review March 5, 2008

  2. Introduction • Location – rural village 40 km south of Masaka, Uganda • Community of 2000 where 19% of the children are orphans • Partnership – Uganda Rural Fund • All volunteer 501(c)3 non profit started in 2005 to provide education and support for disadvantaged children, AIDs orphans, and marginalized communities throughout Uganda

  3. The School • Uganda Rural Fund is building the Hope Integrated Academy • This school is designed to provide young people and adults with education and technical skills as a primary school, vocational school, community library, community center; and health clinic • Currently a after school program for 200 children • Future development will provide housing for 300 AIDS orphans and teach 200 children and adults from the community.

  4. Current and Future Layout

  5. Needs • Water supply • Currently water is not provided to after school students. • Closest water supply is 1 km away from school • Sanitation System • Currently using deep pit latreens • Need system for up to 300 children • System • Rainwater harvesting • Ecological sanitation system with dry composting • Future work on Well drilling

  6. Water Storage • Capacity for next two years – 250 after school children • Usage – 5 L/day • Size estimate 100,000-120,000 L

  7. Storage Tank • Options • Ferrocement tanks • Polytanks

  8. Ferrocement Construction • Tank Size • Height 8 ft • Diameter 18 ft • 57,000 L • Steps • Outline tank placement • Dig and Level ground with 1o slope • Lay mesh rebar for floor • Extend Rebar for walls • Outline with wire mesh • Pour concrete for floor keep wet for days • Bend rebar for roof • Plaster walls • After week Seal it • Total Time 2 weeks

  9. Ferrocement Tank • 5/16 rebar (40’ pieces) - > 30 pieces @ 5.71 = $171.30 • 6x6x10x10 Welded Wire Mesh (7’x200’ rolls) -> 1.5 @ ? = ? • ½” Hardwire Cloth (4’x100’ rolls) -> 2 @ ? = ? • Tie Wire (big loop bundles) -> 3 @ ? = ? • Cement (50 lb bag) - > 80 @ 13.14 = $1051 • Sand (yd3) -> 5.5 @ 34.29/truck = $68.58 ? • Water (L) -> 3800 @ ? = ? • Aggregate (yd3) -> 4.5 @ 40/truck = $80.00 ? • Hog ring staples (boxes of 10,000) -> 2 @ ? = ? • Supporting poles for ceiling -> 15 @ ? = ? • Spacers for floor -> 65 @ ? = ? • Labor -> 2 weeks = ? Total/tank = ~$3000

  10. Poly Tanks • 24,000 L Tanks -> 4 @ 3,439 = $13,756 • PVC Pipe connectors, Hand pump?, drain • Steps • Dig and level ground, sight slope for first tank • Place tanks • Connect with pipes 3.22 m – 10.5 ft Inflow 3.4 m – 11 ft Outflow Sludge Drain Settling Tank

  11. Comparison of Tanks Ferrocement Advantages Cheaper Larger Capacity Disadvantages Construction time Complexity of construction Could crack Permanent Poly tank Allows for a settling tank Can be improved or easily expanded Can be moved/not permanent Cost UV degradation

  12. Tank Placement

  13. 11 ft 2 ft

  14. Rainwater Flow

  15. Elevations

  16. Elevations

  17. Elevations

  18. Collection system Debris collection- leaf screen Gutter system- facia, gutter attachment Disinfection- chlorination

  19. Large particle collection • 3 ft sections • $1 • $6

  20. Fascia

  21. disinfection • Boiling • Rapid sand filter • Slow sand filter • SODIS-solar disinfection • Filtron- porous clay filter • Electrical Ultraviolet • Chemical disinfection-chorlination

  22. Chlorination • sanitization with 20-ppm chlorine for 30 to 60 minutes. Higher concentrations or longer soak times will increase effectiveness of sanitization, but we do not recommend using higher than 50-ppm chlorine in any case. Repeated sanitization at higher concentrations can cause corrosion of stainless steel drinking valves, manifolds, and room distribution piping in an automated watering system. • Bacteria- Effective at reasonable CT values for IWPD use. • Viruses -Effective at reasonable CT values for IWPD use. Use EPA SWTR CT table for recommended CT values (Table 1). Giardia Cysts Effective at reasonable CT values for IWPD use. Use EPA SWTR CT tables for recommended CT values (Appendix B). Cryptosporidium Oocysts Ineffective, even at high CT values. Not practical for IWPD use. • Effect of pH- Disinfection efficiency increases with decreasing pH. Recommend pH less than 8.0 to ensure presence of hypochlorous acid (HOCl). • Effect of Turbidity- Higher turbidity generally reduces disinfection capability. Higher dosages may be necessary to ensure the presence of free chlorine after oxidation of organic matter. • Health Effects- Chlorine, THMs and HAAs have potential health concerns at elevated levels. IWPD manufacturer-recommended dosages are not likely to cause adverse health effects for healthy adults.

  23. Clean Water Supply • The Hope Integrated Academy is located in an area of Uganda that lacks significant available groundwater, yet the area experiences two major rainy seasons per year. • Given the annual rainfall data and the large collection area afforded by the academy building, the EWB-UMN design team has chosen to implement a rainwater harvesting system for the Hope Integrated Academy.

  24. Clean Water Supply: System Overview • The system consists of: • Rainwater catchment system to collect the water from the roof with protected gutters. The gutters will attach to the roof frame. Downspouts and piping will convey the collected water to the storage structures. • First flush system to prevent the solids and contaminants from the roof entering the storage tanks and to clean the gutters. • Initial filtration to separate additional solids from entering the storage tanks. • In-line chlorination treatment to ensure potable drinking water • Water storage structures to hold 120,000 liters of water in two above ground concrete tanks located behind the school. These tanks will gravity feed water to distribution outlets.

  25. Attachments • Current resources are boards from the frame that extend to the edge of the roof. The type of timber, age, and expected time duration Is unknown. • The picture shows John Mary looking at the roof frame. The arrows are not real.

  26. Gutter System Expenses • Numbers supplied by Uganda Rural Fund

  27. First Flush System As the chamber fills, the ball floats up and seals on the seat, trapping first-flush water and routing the balance of the water to the tank. Ref: The Texas Manual on Rainwater Harvesting. Texas Water Development Board. 2005

  28. Sizing the First Flush System • The recommended diversion of first flush ranges from one to two gallons of • first-flush diversion for each 100 square feet of collection area. • If using a roof for a collection area that drains into gutters, calculate the amount of rainfall area that will be drained into every gutter feeding your system. • There will be 3 downspouts on each side. • The PVC pipe will be 4 inches diameter, 8 feet long leading into 1 ft cubed holding tank. Sixteen gallons will be collected at each location.

  29. Roof Washer • The roof washer, placed just ahead of the • storage tank, filters small debris for • potable systems and also for systems • using drip irrigation. • All roof washers must be cleaned. • Without proper maintenance they become clogged and may become breeding grounds for pathogens. • The box is placed atop a • ladder-like stand beside the tank, from • which the system owner accesses the • box for cleaning via the ladder. Ref: The Texas Manual on Rainwater Harvesting. Texas Water Development Board. 2005

  30. In-Line Chlorinator • CTI 8 Chlorinator is an inexpensive, low-maintenance, non-electrical, appropriate-technology apparatus. • It is capable of delivering a controlled dosage of chlorine sufficient to inactivate most pathogens • The CTI 8 accomplishes disinfection by directing water flow over solid chlorine tablets in a simple configuration of PVC tubing. Compatible Technology International (CTI)

  31. In-Line Chlorinator • Costs • A CTI 8 chlorinator can be built and installed for around $100.00 US per unit. • For a typical community of 200 people, monthly operational costs including chlorine can be expected to be between $5 and $10 US, depending on various factors such as temperature, level of contamination and quantity of water flow. • Materials • The chlorinator is constructed of 3-inch and 4-inch PVC pipe and fittings, and ¼-inch PVC plate. • The CTI 8 can be built in a matter of hours using basic hand tools. • It uses chlorine in the form of calcium hypochlorite tablets approximately 2 ½ inches / 6.35 cm in diameter.

  32. In-Line Chlorinator Criteria • Requires pretreatment • Settling tank and filtration • Requires zero water pressure • Chlorine concentration measurements at outlet with color coded chlorine detection kit

  33. In-Line Chlorinator • Training program on construction, installation and maintenance of the equipment • Include training programs on alternative treatments such as UV light and sand filters

  34. SANITATION • Ecological Sanitation – Dry Composting

  35. Design Objectives • (1) Prevent disease • (2) Protect environment • (3) Return nutrients to earth via composting and agricultural application • (4) Provide culturally accepted sanitation • (5) Maintainable • (6) Convenient to use • (7) Affordable • (8) Sufficient for capacity (250 people, ~80% Children) • (9) Constructible • (10) Prevent Odor (anaerobic processes)

  36. System Components • Elevated masonry sanitation structure • Low-cost urine diverting toilets with separate collection systems Temporary storage space directly underneath toilets • Movable collection containers (>.25 m3) • Long-term storage area adjacent to sanitation structure • Composting education, hygiene education

  37. Design: System Use • 250 daily users within 1 year • School to house 300 orphans within 2 years • 20% adults (50) • 80% children (200) • Density of faeces: 1000kg/m3

  38. Design: System Use • Solid waste volume • Adult Saturated vol: 1.37x10-4 m3/day x 50 adults = .00685 m3/day (conservative as saturated) • 50kg/adult/yr (saturated); 11kg/adult/yr (dry) • Child Saturated vol: 9.60x10-5 m3/day x 200 children = .0192 m3/day (conservative as saturated) • 35kg/child/yr (saturated); 7.5 kg/child/yr (dry) • Based on conservative weight ratio of 30 yr to 10 yr old (M 170lb:85lb = .5; F 135lb:88lb=.65) • TOTAL DAILY VOLUME = 0.02605 m3/day • TOTAL MONTHLY VOLUME = .7815 m3/month • TOTAL 6 MONTH VOLUME = 4. 7 m3/6 month Resource: World Health Organization

  39. Design: System Use • Liquid waste volume • Adult Vol: 400L/yr (.4 m3)= 1.10 L/day (.001 m3/day)(conservative as saturated) • Child Vol: 322L/yr (.322 m3)= 0.77 L/day (7.7x10-4 m3/day)(conservative as saturated) • TOTAL DAILY VOLUME = 467.5 L/day (.4675 m3/day)

  40. Design: Storage • Solid: 4.75 m3/6 month • .25-.5L ash per use • As solids dry, volume reduces 80%, so ash addition is countered by reduction • Design assumes solid waste is always saturated, so assumptions remain conservative

  41. Design: Storage • Containers: To store 4.75 m3 for • 40 gal (80% of 50 gal cans) = .189 m333 containers • 2’ x 2’ x 3’(garbage can) = .34 m3  14 containers • 2’ x 2’ x 4’ (large garbage can) = .45 m3  11 containers • Storage Area required = 6.5 m x 2.5 m

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