Comparing the Imhoff/ Faustformel minimum slope curve to that of Macke / ATVA 110 (1988), it is clear that large diameter pipes (> DN 800 (32'')) as per Imhoff require significantly greater slope than that of ATVA 110 (1988). The results of Macke were further refined by Pecher et al. In 1991, in the form of differentiated calculations based on a variation of the sediment transport equation with partial filling (h_{t} / d = 0.05 to 0.3). It is worth noting that part of the fill factor has a significant influence on the size of the minimum slope. The lower the partial filling degree, the greater the slope needs to be in order to allow, under otherwise identical conditions, a depositfree operation ATVA110:2001 [Peche1991c].
Similar conclusions by Sander came in 1994 on the basis of new findings on sedimentation. It therefore recommended to dimension pipes with a diameter of d ≤ 1000 mm (40 in) with a larger specified minimum slope as in ATVA 110 (1988). He also confirmed the mean particle diameter of the sediment as d_{50} = 0.35 mm [Sande1994].
All the above analyses and suggestions were reflected in the new edition of the ATVA 110 in 2001. Thus, there are now formulas and tables for determining the limits I_{C}, v_{c}, τ_{min} for circular pipes DN 1504000 with a partial filling h_{t}/d >0,1 , for both combined and storm sewers [ATVDVWKA 110:2001].
The picture shows the limit curves thus determined for the required minimum slope for a depositfree operation for h_{t} / d ≥ 0.1 and h_{t} / d ≥ 0.5. From this it can be deduced that the required minimum slope is significantly influenced by:

the degree of capacity utilization (filling height),

the circular pipe diameter of the sewers d,

the dewatering process and thus indirectly on the characteristics of the transported solids within the wastewater.
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