For practical reasons, sedimentation shafts are arranged in the inlet area of stormwater tanks, inverted siphons, lifting and pumping stations, prior to flow meter locations, as well as at the end of branch sewers or immediately before their entry into the main sewer. Due to the biochemical decomposition processes, aeration is required when they are used in combined systems [ATVA166].

As a general rule, sedimentation shafts are designed with a length of 2.00 m (6.6 ft) and a width of 1.50 m (4.9 ft). The depth below the pipe invert depends on the sedimentation rate, which, considering the aspect of an economic cleaning frequency, is dimensioned for a sediment quantity of at least 5.0 m³ (176.5 ft³) [FI-VSB].

Generally, it can be observed that although semi-central systems allow for a targeted sedimentation of solids, they cannot contribute to a reduction of the entry of solids and thus, to a standard deposit-free operation of sewage systems.

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