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will then adhere to the wall of the sewer, causing a reduction in capacity. Grease may be removed by jetting, rodding, winching or hand excavation. Grease removal from sewer systems and pumping stations is an expensive operation and it is often more cost-effective to identify the source and take action to prevent further discharge of greasy effluents. |
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This is the build-up of material typically found on the walls of sewers. The consistency and thickness of the material build up on the sewer wall can vary significantly, either as a result of chemical reaction between the sewer material and the sewage, or due to infiltration into the sewer. The encrustation should only be removed if it is causing a problem, as removal always carries a risk of damage to the fabric of the sewer. |
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Full or partial collapse will obviously result in problems. The structural integrity of the sewer can be severely weakened by the loss of part of the pipe fabric, which may collapse into the sewer, and result in a blockage. This situation may be made worse if repairs are carried out to the sewer, and the defective pipe, surplus construction material or fill is not removed from the sewer, inspection chamber or manhole. |
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Defects in the sewer fabric or jointing can lead to the ingress or egress of water and solids. Fines, or other solids which may be carried in by the infiltration water, can settle out and reduce the hydraulic capacity of the sewer or cause blockages. |
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Under the specific by-laws of individual countries, discharges of 'trade effluent' should be controlled so as to reduce their impact on the sewer system, the sewage treatment facility and therefore the environment. Therefore, trade effluent should not normally cause cleaning problems other than when a pre-treatment plant |
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