Protection of water pipeline against contamination 2

[mayor610]

Dear All,
I am dealing with laying of MS pipe for raw water in Chhattisgarh. Now at a few places the raw water pipeline has been laid in drains which get completely full right upto the top of the culvert level with rainwater during monsoon which last for 03 months.

In such a scenario to protect the raw water gravity main from possible contamination ---Is encasing the 1275 mm MS pipe with 150 mm thick M20 Concrete all round the pipe a fool proof solution.

Thanks & regards

 

[cvg]

probably not

 

[bimr]

No, it is not a solution.

Is it possible to use a smaller diameter pipe as a pressure pipe?

 

[mayor610]

No the gravity Main has already been laid.

At places where the Raw Water gravity Main runs close to existing RCC open drain [ Say about 2m horizontal distance away and almost at the same elevation], the Raw Water Gravity Main has been provided with the 150 mm thick coarse sand encasing all round in the form of a box. That is fine.

But the real concern is where we run our MS pipeline through open drain.

 

[cvg]

when you say open drain, my understanding that would be a ditch or canal?
mild steel with what kind of joints?

so you have a couple of issues to consider:

scour - high flows (depth and velocity) may undermine the pipe. scour protection would be required. the 150 encasement will not prevent scouring or protect against damage caused by it

floatation - the high water level could move the pipe vertically or horizontally. heavy anchors or backfill would prevent that.

Debris - debris in the canal might damage the pipe. a thin concrete coating would provide only minimal protection against debris

Corrosion - your method will not prevent corrosion

leakage through joints - water might leak through the joints and a better encasement, either steel casing pipe or thick reinforced concrete could protect against that. 150 is probably too thin and would need a lot of steel to prevent large cracks that would allow water to penetrate.