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CHAPTER 5
DISCUSSION, CONCLUSION AND RECOMMENDATION
5.1. Discussion
Within doing the design of drainage system for Talychaung, the preliminary
investigations and surveying are needed and first carried out. In order to estimate the
design discharge, storm water are considered and determined. For the estimation of
storm water, the rational equation is used. In this study, maximum rainfall data from
2013-2017 is used. Impermeability is used from site surveying.By using the the
Manning formula (n=0.015), the design of drainage system is manually calculated.
After determining the discharge of storm water, proper sizes and the slopes of the
main drain and access drains are calculated. The main are trapezoidal- shape in lined
concrete and access drains are rectangular-shape in lined concrete. If existing drains
are correctly designed, they should not require expensive or major repair. The existing
design is not enough to store the rainfall and the unlined drain is not convenient to
flow: The new design is convenient to store the maximum rainfall data and the lined
drain is convenient to flow. And the new design will present flooding and slipping on
roads.
5.2. Conclusion
To design the storm water drain, first we determine the storm water runoff or
discharge. To determine the discharge, we need the catchment area , rainfall data and
impermeability factor. The catchment area data was collected from the Department of
Agricultural Land Management and Statistics. The rainfall data was collected from
the Department of Meteorology and Hydrology. And choose the maximum rainfall
data. This data is not convenient for calculating. So, we used the rainfall intensity of
100mm per hour. If no local IDF curves are available, a rainfall intensity of 100 mm
per hour can be assumed.( This value is for tropical countries, when catchment areas
smaller than 150 ha). Impermeability factor was collected by surveying. Check the
existing main drain design and access drains (24 drains) design. Next, design the main
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drain and access drains. The total capacity of access drains is used for redesign the
main drain. Finally, we check the volume of main drain and access drains. Main drain
1
is redesigned the size of the main drain, 9 m width, 2 m depth, slope ,freeboard
1023
0.5 m are designed with trapezoidal shaped in lined concrete. Access drains is
1
redesigned the size (8 drains, 0.55 m width, 0.9 m depth, slope freeboard 0.3 m,
88
1
6 drains, 0.6 m width, 0.9 m depth, slope freeboard 0.3 m,10 drains, 0.35 m
100
1
width, 0.55 m depth, slope freeboard 0.3 m) are designed with rectangular shape
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in lined concrete. The new design is sufficient enough to store the max: rainfall and
prevent for flooding and don’t slip on roads.
5.3. Recommendation
In this study, the Rational Method is used for storm water discharge and the
Manning’s Formula is used for storm water drain design. The recommendations are as
follows;
(i) If rainfall intensity duration curve is used, this design is perfect.
(ii) To stand on the curb and use a rake or pitch fork to clear leaves, limbs, and debris
from the catch basin.
(iii) To inspect the storm drain in front of your house or business is before a rain
storm.
(iv)To monitor and clean the catch basin in the fall when the trees are shedding their
leaves.
(v) To maintain the opening to catch basin by clearing away garbage.
(vi)Grass or other vegetation should be planted along the sides of the drains to prevent
erosion and to maintain the existing drain system and facilities.
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