Trunk Sewers and Water Mains

[wangedmund]

I ｒｅｃｅｎｔｌｙ　ｒｅｃｅｉｖｅｄ　ａ　ｐｈｏｎｅ　ｃａｌｌ　ｆｒｏｍ　ａ　ｒｅｃｒｕｉｔｉｎｇ　ａｇｅｎｃｙ．　Ｔｈｅｙ　ａｒｅ　ｌｏｏｋｉｎｇ　ｆｏｒ　someone specifically　ｆａｍｉｌｉａｒ　ｗｉｔｈ　ｔｒｕｎｋ　ｓｅｗｅｒｓ　ａｎｄ　water main design. I have some experience in designing water mains, sanitary and storm sewers for subdivisions. So What makes trunk sewers and water mains different? I understand that size could be one factor. What else shall we have to take into account when designing trunk sewers and water mains? Thanks a lot!

 

[edcard]

Well, for starters, the size (diameter) difference between trunk sewers and water mains is very likely to be significant, but you also have materials, gravity vs. pressure flow, etc.

You may very well have the required expertise; the recruiting agency people are just parroting some written material.

 

[wangedmund]

Thank you for your explanation, edCard. For subdivisions, PVC pipes are often seen as trunk water mains and sewers. I would imagine that concrete pipes shall be used as trunk water mains and sewers.

 

[dhengr]

Wangedmund:
Only one of them carries a potable liquid, so interconnection is not a good idea.

 

[cvengr]

Huge difference.

Sewers typically flow half full in underground pipelines with clean-outs and manholes appropriately spaced. If a force main, then calcs have to be run to verify flow rates to insure no stagnation and nothing becomes cementitious.

Water lines focus more on limits of 1500 gpm flow within a network between several hydrants, depending upon network topology. Also water lines might not be fire protection lines. Depends upon the situation.

 

[wangedmund]

Thank all of you for your kind responses. I am sorry that I did not make it clear. I meant to ask what makes a trunk water main different from an average water main, and a trunk sewer from a regular sewer, besides their sizes. Thanks again!

 

[cvg]

I would imagine that concrete pipes shall be used as trunk water mains and sewers.

Concrete is generally not used for any type of water main. steel and iron are far more commonly used. and concrete would not be my first choice for a trunk sewer due to corrosion issues.

 

[Althalus]

There really is no difference between trunk and lateral in the usage of pipe. You have flow volume, thickness, diameter, and geometry. That's it. With these variables might come other issues such as water table, depth of cover, clearances to other pipes, etc.

You also have issues with fittings. You generally want to stay away from gate valves on larger lines. You also have availability of parts in different sizes.

Basically, the difference isn't with the "label" of trunk, main, lateral or so forth (unless specified by the jurisdiction). The difference really comes from the flow requirement and all that is dictated by the same. Apart from that, if you've designed some water lines, you've designed some water lines.

There is, however, quite a difference between individual unit (house, office, other building) piping vs system piping. The principles are the same. But the application, fittings, pieces, etc. are different.


Althalus

 

[Satybarole]

Hi,
I don't think there is different between trunk sewers and water mains, And If there is different between them then that was inflicted.

........................

HSE Engineer LNG

IHI engineering and construction

 

[coloeng]

The normal difference between a trunk water line and regular water line is that a trunk water line typically doesn't have individual services connected to it and is meant to serve a larger area. The same would be true of a trunk sewer. It collects the flow from many regular sewer lines. Think of it as a tree, the trunk is the main part and then it branches out, with the branches being the regular water or sewer lines.