minimum velocity problem

[WaterGIS]

Greeting
im building sewercad model for a network and im facing minimum velocity problem at the beginning of the line .. the loads are low at the starting point
this is my first model
can anyone help me
many thanks

 

[bimr]

What slope are you using?

c) Slope
1) All sewers shall be designed and constructed to give mean velocities, when flowing full, of not less than 2.0 feet per
second, based on Manning's formula using an "n" value of 0.013. The following minimum slopes shall be provided;
however, slopes greater than these are desirable:

Minimum Slope in Feet
Sewer Size Per 100 Feet Flow (mgd)
8 inch 0.40 0.49
10 inch 0.28 0.75
12 inch 0.22 1.07
14 inch 0.17 1.43
15 inch 0.15 1.61
16 inch 0.14 1.85
18 inch 0.12 2.35
21 inch 0.10 3.23
24 inch 0.08 4.13
27 inch 0.067 5.17
30 inch 0.058 6.37
33 inch 0.050 7.66
36 inch 0.046 9.23
42 inch 0.036 12.41

 

[TerryScan]

As bimr pointed out, most regulations specify minimum velocity when flowing full.

At the top of storm systems, where there is not much flow, it is common to have velocities below the minimum. If one is able, it helps the pipes to stay "self cleaning" if you make the slope steeper for these pipes.

However, in some regions, this is not feasible. As long as they have the minimum slope for full flow, at least it will facilitate cleaning using a water truck if sediment accumulates.

 

[BUGGAR]

As a side note, the new low flush toilets mandated in San Francisco provide inadequate water flow to clear the solids from the lines.

 

[WaterGIS]

many thanks, i appreciate ur feedback ...