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
 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
2
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.
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Current and Future Layout
4
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
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Water Storage
 Capacity for next two years – 250 after school children
 Usage – 5 L/day
 Size estimate
100,000-120,000 L
Rainfall per month
160000
140000
120000
Rain (L)
100000
80000
60000
40000
20000
0
Month
Etembe 1984-2000
6
Masaka 1920 -1944
Storage Tank
 Options
 Ferrocement tanks
 Polytanks
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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
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Ferrocement Tank
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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
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
3.22 m – 10.5 ft
 Connect with pipes
Inflow
3.4 m – 11 ft
Settling Tank
Sludge Drain
10
Outflow
Comparison of Tanks
Ferrocement
Advantages
Cheaper
Larger Capacity
Disadvantages
Construction time
Complexity of construction
Could crack
Permanent
11
Poly tank
Allows for a settling tank
Can be improved or easily
expanded
Can be moved/not permanent
Cost
UV degradation
Tank Placement
12
11 ft
2 ft
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Rainwater Flow
Elevations
Elevations
Elevations
Collection system
Debris collection- leaf screen
Gutter system- facia, gutter attachment
Disinfection- chlorination
Large particle collection
• 3 ft
sections
• $1
• $6
Fascia
Gutter Price list
PVC piping
downspouts
90 deg elbow
45 deg elbow
10 ft of gutter
PVC cement
downspout adapter
hanger system
epoxy paint
leaf guard
size
5"
5"
5"
5"
5"
1 gal
5"
quantity
6
16
6
24.05
2
6
22
1
2.5
$cost/ unit $cost
5.88
35.28
6.39
102.24
3
18
12.88 309.764
4
8
0
2.98
65.56
44
44
63
157.5
total
740.344
disinfection
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Boiling
Rapid sand filter
Slow sand filter
SODIS-solar disinfection
Filtron- porous clay filter
Electrical Ultraviolet
Chemical disinfection-chorlination
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.
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.
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.
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.
Gutter System Expenses
Material
•Numbers supplied by
Uganda Rural Fund
Gutters
Face
Boards
Value
Units
1,200,000
UGX
700000
UGX
Brackets
320000
UGX
Nails
Painted
Fascia
60000
UGX
100000
UGX
500000
UGX
120000
UGX
3000000
UGX
1900
USD
Labor
Unexpecte
d
Total
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
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.
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
In-Line Chlorinator
•CTI 8 Chlorinator is an
inexpensive, low-maintenance,
non-electrical, appropriatetechnology 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)
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.
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
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
SANITATION
 Ecological Sanitation – Dry Composting
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)
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
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
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
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)
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
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
 Budget
 Rainwater collection $1900
 Water Treatment
$500
 Water Storage
$15000
 Sanitation
$5000
 Hydrogeology
$700
 Total
$23,100
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Implementation Plan
 Future phases
 Well
 Water tower
 Expansion as school grows
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