SURFACE STORM SEWAGE DRAINAGE SYSTEM, NIGERIAN CITIES CHOICE FOR STORM DISCHARGE
1Arc.Boyce A. Odoko 2Olokpo Morgan I. 3Ealefoh Dominic E. 4Onwuka Okechukwu
1Department of Architecture, National Institute of Construction Technology, Uromi, Edo state.
2,3,4Department of Building Technology, National Institute of Construction Technology Uromi, Edo State.
Email: odokoarch@yahoo.com
ABSTRACT
Throughout Nigeria, from small to large cities, surface open channel storm sewage drainage system is the choice for rain water disposal. Even municipals with flat terrain, with all constrains in sloping the storm drain, they invest on the open channel storm drainage system, still. These open channels accumulates debris, solid materials, some of the solid objects are deposited into the channels by the city inhabitants. Besides the solid objects, there are also large deposits of silt and sand that flows into these open drain channels. The debris, silt and sand deposited into the open drain channels stays there permanently with no attempt of removing them by the local city authorities. In effect, you have stagnant water with solid objects, silt and sand deposit in the open channels, this becomes permanent home for mosquito, frogs and all types of insects. At some point, the stagnant water generates extreme bad odor, circulating through the wind around the community. At this point, it has become environmental pollution issue, a public health problem for the inhabitants. This is the situation in most Nigerian cities with the surface storm sewage drainage system. People get infected by malaria every day from mosquito attack, yet municipal government authorities allow these surface storm sewage drainage system to stay with stagnant water without cleaning them. Take for example, Yenagua, the capital city of Bayelsa State, Nigeria, a coastal city with major flooding problem due to seasonal heavy rain fall. The city’s choice for storm drain is the surface open storm sewage drainage system. Throughout the city, wherever there is any storm drainage, it is the open channel storm sewage drainage system. The city has a flat landscape and therefore, it is almost impossible to slope the surface storm sewage drainage system to enable the water drain away into the river and creeks. In addition to this problem, the roads in the city are constructed and elevated above ground level for the convenience of the automobile. As a result, there is constant stagnant ground water on both sides of the roads in the city. These elevated roads seems to imply a construction that gives preference to the automobile. This is constantly creating flooding whenever it rains heavy, the rain water backs-up to the buildings and flows into the river as well. The buildings get flooded time after time from the heavy rain fall. As it happens in other cities with surface storm sewage drainage system, the surface storm drainage in Yenagua are constantly receiving debris, solid objects sometimes from human inhabitants, depositing them and when heavy rain falls, these solid objects are injected into the drain channels along with the rain water. Therefore, most of these surface storm sewage drainage systems are clogged with solid objects with rain water.
They become very good home for mosquitos, frogs, snakes and all types of insects. This is a major health problem and financial cost on the city inhabitants, they facing with constant malaria infections, due to the presence of the mosquitos. The stagnant water generates diseases and each time the city inhabitants are infected with disease, they bear the financial cost for treatment.
When people get sick, they do not go to work as a result, it reduces work productivity and subsequently, it lowers the economic base of the city. Therefore, this letting of debris, solid objects, silt, sand and stagnant water to stay in the surface storm sewage drainage system must be properly addressed by the local municipal authorities. They need to periodically clean up the surface drain channels to avoid the constant environmental pollution in the community. Better yet, they should invest in underground storm sewage drainage system.
Keywords: Surface Storm Drainage, Open Channel Drainage, Storm water Overflow, Flooding, Blockage, Debris