I I - part - usaid

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(2, Embankment StLUctUre (Dike). This is a
stczage pond which is -'me -E -ZT-Hg --avantage of natural
siopes which direct run-off waters to the pond area, and
constructing a dike to hold those run-off flows for latter
dry season use. A study must be made to determine that the
proposed pond bottom is reiatively impervious. This being
the case it is sometimes possible to utilize a combination
of digging materials rrom the proposed pond bottom and using
these materials to form a homogeneous embankment. Often,
however, the materials are not structuraliy sound and
materiais must be imported to construct the dike, A close
estimate of cost can be deveioped when the haul distance is
known. If impervious soais are expensive to bring to site a
zoned embankment can ne designed where the expensive
impervious soils are only utilized in the central section of
the dike. The run-otl area must be caiculated so the spillway
may be designed to dischaige excess flood run-off and
prevent breaching of the diKe. For this and numerous other
reasons, each site requires a thorough engineering study.
Each project has to be individually designed based on site
conditions including soils, and potential run-off during
heavy rainy seasons.
t3) Submerged Embankment Dikes;. These
projects are constructed in areas which are periodically
deeply flooded. The concept is to build a dike to retain
water ,n selected areas after I-food waters recede. The
structure, which is unde water during floods, must be
caretuily designed for similar reasons to those noted in (2)
above, but design must also take into account the pressure
which develops as waters recede fiom one side of the
embankment as the food waters diminish. The rate of the
drop in elevation determines the pore pressure which
develops, and the erbankment must ne designed to withstand
these forces. Hign forces could requ±re very expensive
construction and may preclude economic viability of a
project. However, if the water recedes slowly, a less
expensive structure can De successtlu.. Here again, each
project requires a complete engineering study.
(4) Pi.ter -,ystems and iJeii.s
Filtet systems wili be generally
composed of a filter box airangement of sand,;,j:a-,el/
charcoal connected to an inlet pipe ari outlet pipe to a
storage well. These systems are easily c3nstr'ucted by local
villagers with some minor technical assistance ron the
technical engineering staff. Likewise shallow wells are