Cleaning Pressure Sewer Hydraulically

[mflam]

We have a 24 inch diam force main on a waste water pump station.
The length of the pressure line is 5,800 lf. In profile the line has two low points before discharge to a chamber. Gravity flow takes over.
From the point of discharge to the most distant low point is 2,200 lf.
There is evidence that the low points are becoming restricted by sedimentation.
It is very difficult to take the force main out of service.
I believe we could clean the line while it is still in service.
If a high pressure hose could be pushed into the force main 2,200 feet, counter to the direction of flow, the jet would suspend the sediment. While the jetting was taking place, the pumping rate could be increased to scour the solids out.
Has anyone done this type of cleaning?

 

[bimr]

Not familiar with that.

The most common method of cleaning force mains is by use of polyurethane swabs, which are better known as “poly pigs.” Poly pigs are available in various densities and surface coatings. To use this method, poly pigs are inserted into the pipeline, which is then pressurized behind the pig. As the device travels through the force main it scours the
inside of the pipe.

Normally, the use of poly pigs requires that the pump station be temporarily shut down. Provisions must be made for handling incoming wastewater, either through bypass pumping or by providing adequate short-term storage.

A launching point must be available for insertion of the pig and access at the discharge end of the force main must be available for removing the pig. Insertion facilities can be located within the pump station. Several launching and retrieval stations are usually provided in long force mains to facilitate cleaning the pipeline.

The following factors should be considered when using poly pigs to clean force mains:

• Provisions must be made for bypassing the pump station or providing alternative wastewater storage while the force main is being cleaned.

• A launching station must be provided, either in the pump station or at the beginning of the force main.

• External pumps and a water supply are needed to propel the pig through the force main.

• The force main must be drained any time it is worked on.

• Provisions must be made to track the pig through the force main in case it gets hung up and can
not be removed except by digging up the pipeline.

• The debris removed by the cleaning operation must be collected and taken to an
appropriate disposal site.

https://www.neiwpcc.org/neiwpcc_docs/WEBOM&R.CH7.pdf

A newer technique is ice pigging.

http://www.utilityservice.com/dwnlds/articles/MiddleburyIcePiggingBoard24x36wLogo.pdf

 

[gerhardl]

I have no direct knowledge of the systems, but the thought have some practical solutions out there. If they might be practical to use in your case is another thing.

http://www.pipeandplant.com/services/large-diameter-sewer-cleaning/

https://www.youtube.com/watch?v=rXGnusUcnU4

 

[MikeHalloran]

Wow! Ice Pigging is a real forehead-slapper of an idea.


Mike Halloran
Pembroke Pines, FL, USA

 

[amlinerrichard]

I have seen demos of Ice Pigging. And if it gets stuck wait a few hours and it has melted.