The Design of Drains for a Community (Ayeduase)
DRAINAGE SYSTEM DESIGN
Objective: The drainage system for the project functions to ensure effective transportation of storm water in order to avert the occurrence of flooding of the site. It also helps to safely discharge grey wastewater from buildings to their end points.
NATURE OF SITE, LOCATION AND TOPOGRAPHY:
The sight, predominantly sandy, slopes to the south-western part. Due to this topography, water flows to the southern part of the community and since there are insufficient drains to collect the water especially during heavy downpour, flooding occurs.
Two U-drains are located along the road that joins the storm drain located at point X on the map. One from the Ayeduase gate with the other at a distance Y, away from the storm drains at X. There are no further drains along the road until a culvert at a point, P on the map. The distance of no drains is where most flooding occurs during heavy downpour of rain. From the culvert is a drain that joins the storm drain with double culvert at a point C. This storm drain connects to the main stream behind Nana Adoma Hostel. From the Ayeduase gate downwards is another drain that joins the main stream represented by a blue line on the map. All drains form a network and later join the storm drain which in turn empty into the stream.
STANDARD DESIGN
The Road Design Guide by the Ghana Highway Authority was used as the standard for the design of all drains
DESIGN RETURN PERIOD
A 20 years return period was used in the design of all drains, both secondary and tertiary
IDF CURVE
Using rainfall-intensity-duration curve for Kumasi, obtained from the Kumasi Metropolitan assembly, the rainfall intensities for a chosen return periods can be estimated. The total peak flow for each of the catchment areas can also be estimated with the values from the IDF curve. This is used for the sizing of the drains.
CALCULATION OF DISCHARGE
For the discharge of each drain, the rational formula will be used with the assumption that the same
Objective: The drainage system for the project functions to ensure effective transportation of storm water in order to avert the occurrence of flooding of the site. It also helps to safely discharge grey wastewater from buildings to their end points.
NATURE OF SITE, LOCATION AND TOPOGRAPHY:
The sight, predominantly sandy, slopes to the south-western part. Due to this topography, water flows to the southern part of the community and since there are insufficient drains to collect the water especially during heavy downpour, flooding occurs.
Two U-drains are located along the road that joins the storm drain located at point X on the map. One from the Ayeduase gate with the other at a distance Y, away from the storm drains at X. There are no further drains along the road until a culvert at a point, P on the map. The distance of no drains is where most flooding occurs during heavy downpour of rain. From the culvert is a drain that joins the storm drain with double culvert at a point C. This storm drain connects to the main stream behind Nana Adoma Hostel. From the Ayeduase gate downwards is another drain that joins the main stream represented by a blue line on the map. All drains form a network and later join the storm drain which in turn empty into the stream.
STANDARD DESIGN
The Road Design Guide by the Ghana Highway Authority was used as the standard for the design of all drains
DESIGN RETURN PERIOD
A 20 years return period was used in the design of all drains, both secondary and tertiary
IDF CURVE
Using rainfall-intensity-duration curve for Kumasi, obtained from the Kumasi Metropolitan assembly, the rainfall intensities for a chosen return periods can be estimated. The total peak flow for each of the catchment areas can also be estimated with the values from the IDF curve. This is used for the sizing of the drains.
CALCULATION OF DISCHARGE
For the discharge of each drain, the rational formula will be used with the assumption that the same