7. spring boxes
DESCRIPTION
7. Spring BoxesTRANSCRIPT
Spring Box Design and Construction
CE 5993
Acknowledgment:Acknowledgment: Lauren Fry
Civil & Environmental EngineeringCivil & Environmental EngineeringMichigan Technological University
Unprotected SpringUnprotected Spring
Figure 1. Unprotected spring in the village of Bilik‐Bikot, Cameroon. Before i f h i b h i ll d ll i hiconstruction of the springbox, the spring water was allowed to collect in this
open pool. Water stagnated, people were able to dip dirty buckets in the pool, and the spring was a mosquito breeding area.
Water‐Related Diseases
(Cairncross and Feachem, 1993)
Choosing a SpringChoosing a Spring
• Why people choose a specific source:Why people choose a specific source:– Water looks cleaner and tastes better.– It is closer than other sources.– The flow is constant and sufficient.
• Other considerations:Other considerations:– Actual water quality (bacteria free? Taste, odor)– Ability for water to drainy– Reliability through dry season– Accessibilityy
Preparation of the SpringPreparation of the Spring
A typical arrangement of an unimproved spring. To prepare for springboxconstruction, the impermeable layer of sand or soil should be removed at the spring pool, down to the impermeable layer.
Spring Box Design: Profile ViewSpring Box Design: Profile View
(Filter may be omitted from design.)
Spring Box Design: Plan ViewSpring Box Design: Plan View
(Filter may be omitted from design.)
Slow Sand FiltrationSlow Sand Filtration
• For a slow sand filter to function, the sand should have an effective grain size of 0.15 to 0.30 mm and uniformity coefficient (D60/D10) less than 5. – D60 is the sieve size that allows 60% of the sand to pass and
D10 i th i i th t ll 10% tD10 is the sieve size that allows 10% to pass. • Minimum height of the sand layer should be 0.5 m, and the
rate of filtration should be no faster than 0.1 to 0.2 3/ 2/h (Vi h t l 1987)m3/m2/h (Visscher et al, 1987).
• For a filtration rate of 0.1 m/h through a clean filter, the minimum head over the filter is 5 cm (Tchobanoglous and B t 2003)Burton, 2003).
• Even with a small spring output like 1.7 L/min, the surface area of the filter must still be at least 1.0 m2.
Rapid Sand FiltrationRapid Sand Filtration
• Filter may be omitted to save money or as aFilter may be omitted to save money, or as a compromise, rapid sand filtration may be usedused.
• For rapid filtration, very coarse sand or small gravel is usedgravel is used.
• In this case the filter is designed to be i l 0 5 l b 1 5 id b 1approximately 0.5 m long by 1.5 m wide by 1
m high, with filter media height of 0.4 m.
ReservoirReservoir• The reservoir should be sized based on the output of th i d t i i th t f tthe source in order to maximize the amount of water that is stored overnight. – For example, if a spring has a maximum output of 6 L/min, p , p g p / ,
assuming that no one draws water between 6:30pm and 5:30am (11 hours of filling), the reservoir size would be 3.96 m3.
– Size may be restricted by available materials and funds, however.Size may be restricted by available materials and funds, however.
• Reservoir walls are made of steel reinforced concrete.• Floor should be sloped and made with smoothed concrete.
• All surfaces inside the reservoir should be smoothed t ll f i l ito allow for easier cleaning.
Typical Construction BudgetTypical Construction Budget
Typical Construction BudgetTypical Construction Budget
Typical Maintenance ScheduleTypical Maintenance Schedule
It is very important that the community and management committee are y p y geducated and trained on the importance of maintenance so the project is sustainable in the long term.
Measuring Spring DischargeMeasuring Spring Discharge
Weir used to determine the output of the springs. A welder was hired to produce this weir from a flat piece of metal roofing materialhired to produce this weir from a flat piece of metal roofing material. All yield and head markings were also engraved on the metal (Mann and Williamson, 1973).
ConstructionConstruction
(Filter sizelimited bymaterials.)
Typical Construction ScheduleTypical Construction Schedule
Completed SpringboxCompleted Springbox
Completed SpringboxCompleted Springbox
Overflow pipe bends down to prevent children from breaking it.
Common Construction ProblemsCommon Construction Problems• Accidentally digging through the impermeable layer may cause
water to be lost from the springwater to be lost from the spring. • When filling the wooden forms with concrete, uneven pressure may
cause the walls to gradually tilt during placement. • When filling the primary filtration and capture area there is a• When filling the primary filtration and capture area, there is a
possibility for blocking the veins augmenting the spring. Be sure that the veins are not blocked by mud. C i th i filt ti d t ith th ft it• Covering the primary filtration and capture area with earth after it is filled with rocks may be appropriate in some places, but where soil is very fine, the earth may end up filtering through the rocks d bl k h l l h hand blocking the gravel layer entrance. In this case, the primary
filtration and capture area can be filled with rocks and covered with a plastic tarp or other impermeable material before covering with earth.
ReferencesReferences• Cairncross, S., and R.G. Feachem. Environmental Health Engineering in the Tropics: an
Introductory Text, Second Edition. Chichester: John Wiley and Sons, 1993.• Fry, L. "Spring Improvement as a Tool for Prevention of Water-Related Illness in Four
Villages of the Center Province of Cameroon," M.S. Report, Civil & Environmental Engineering, Michigan Technological University, 137 pages, 2004.
• Fry, L., J.R. Mihelcic, D.W. Watkins, Improving public health by improving water supply: y, , , , p g p y p g pp yresults from springbox projects in Cameroon. Journal of Engineering for Sustainable Development: Energy, Environment, Health, 2006.
• Huisman L., De Azevedo Netto J.M., Sundaresan B.B., Lanoix J.N., and Hofkes E.H. SmallCommunity Water Supplies: Technology of Small Water Supply Systems in DevelopingCommunity Water Supplies: Technology of Small Water Supply Systems in DevelopingCountries. IRC Technical Paper Series #18. The Hague, The Netherlands: IRC InternationalWater and Sanitation Centre, 1981.
• Tchobanoglous, G. and F. L. Burton. Wastewater Engineering: Treatment and Reuse. Metcalf& Eddy Boston: McGraw Hill 2003& Eddy. Boston: McGraw Hill, 2003.
• Visscher J.T., Paramasiram R., Raman A., and Heijnen H.A. Slow Sand Filtration forCommunity Water Supply: planning, design, construction, operation, and maintenance.Technical Paper Series #24. The Hague, The Netherlands: IRC International Water andS i i C 1987Sanitation Centre, 1987.