TABLE OF CONTENTS A network of sewers or the science of sewers.
Investigations into sewer rehabilitation include assessment of the structural condition, hydraulic performance and environmental impact of the sewer system. The deficiencies and causes of deficiencies are identified so that a rehabilitation plan (known as a drainage area plan) can be developed and implemented in order to achieve efficient operation and maintenance of the sewer network.
A back drop.
Cleaning of sewers may use a large flow of water (flushing) or high pressure water (jetting). Mechanical cleaning methods are common, such as pigging or rodding. Prior to sewer rehabilitation, rack feed boring or drag scraping may be used.
This usually starts with the formation of initial defect during sewer construction or placement (e.g. bad bedding, leaking joints). The defect causes water to flow out of or into the sewer. The joint material may be eroded and the soil may be lost from around the sewer reducing support. Finally the weakened structure collapses. See also below.
See sulphide corrosion.
Any gas in a sewer, including petrol vapour, carbon monoxide, carbon dioxide, hydrogen sulphide, methane or combinations of them.
Computer programmes for the analysis, simulation and design of sewerage systems have been available since the 1970s. Complex models are now readily available. The input to these models includes data on the pipe system, catchment area,...
