|
|
|
|
|
|
|
rodents. The objectives of rodent control in sewers are to institute control programmes to minimize rodent damage to the fabric of the sewer system, damage to the environment, and any risk to health and safety. |
|
|
|
|
|
|
|
|
5.4.10
Sewer Tracing Procedures |
|
|
|
|
|
|
|
|
The technique of adding a dye to the flow in order to be able to identify it downstream is well known. The method is primarily used for determining the route of a sewer by adding dye to the upstream flow and observing where it appears downstream. Whenever flows are low it may be necessary to add water from a tanker or hose to temporarily increase the flow. An alternative method, which is commonly used in Ghana, where dye is not readily available, is to use noise. One operative will gently but repeatedly tap the inside of an inspection chamber while a colleague will listen at another; with experience an operative can readily distinguish a directly connected chamber from an unconnected one. |
|
|
|
|
|
|
|
|
5.4.11
Inspection Chambers and Manholes |
|
|
|
|
|
|
|
|
Inspection chambers and manholes are constructed in sewers to provide access for maintenance and inspection of the sewer. They are generally constructed in sandcrete blocks or in-situ concrete, and are sometimes provided with step irons or ladders for access to the sewer. The sewerage manager should ensure that: |
|
|
|
|
|
|
|
|
manholes and inspection chambers are structurally sound; |
|
|
|
|
|
|
|
|
authorised persons can enter manholes in a safe manner, and in compliance with the sewerage undertaker's safety procedures; and |
|
|
|
|
|
|
|
|
manhole and inspection chamber covers are not a hazard. |
|
|
|
|
|
|
|
|
A reactive maintenance strategy will generally be most appropriate for the maintenance of manholes and inspection chambers. Maintenance work will therefore only be carried out when a problem is reported or otherwise discovered. The routine replacement of manhole covers and frames because of age, expected asset life, etc. to a routine programme, is unlikely to receive |
|
|
|
|
|