|
|
|
|
|
|
|
roots. Mass roots cause the greatest problem, significantly reducing flow capacity, and are the major contribution towards sewer blockages. However, tap roots may be the most difficult to remove. A local excavation is necessary for removing root intrusions. In order to minimize the effects of roots on the sewer, trees should be planted at least 6 m away from the line of sewers. |
|
|
|
|
|
|
|
|
A blockage is a full or partial restriction within the sewer, which may result in flooding or premature operation of overflows. Blockages can occur on any sewer length, but are more frequent in small diameter sewers. Most blockages require a specific maintenance action, e.g. rodding to clear them, but on occasions the flushing action caused by multiple WC operations may move the blockage further down the system to a location where it becomes less significant. |
|
|
|
|
|
|
|
|
Poor constructional practice in Ghana has resulted in numerous instances of new connections being made to existing sewers where the lateral connection protrudes through the pipe wall and into the sewer. This reduces cross-sectional area, and may lead to blockages. In some instances the structural damage caused to the sewer, by a poor connection, may lead to deformation and eventual collapse. Intrusions can also be caused by the careless laying of services through sewers. This also reduces cross-sectional area, and can cause safety problems. Any reduction in cross-sectional area will restrict the flow, and under certain conditions, can result in a build-up of debris which must be removed. Excavation is the most appropriate form of remedial action to remove intruding connections. |
|
|
|
|
|
|
|
|
Grease is generally associated with non-domestic users, e.g. hospitals, schools, restaurants, etc., and is often due to inadequately sized, badly designed, inadequately maintained or missing grease traps. A high-temperature effluent containing grease will usually cause problems as the effluent starts to cool. The grease |
|
|
|
|
|