Help: Surge pressure in Fresh water pipeline

[convitco]

My dear friends,
we are performing the Fresh water supply system for a 1200 MW thermal power plant with some basic information as below:
- pumping station: 3 pumps, each pump Q = 560 m3/h, 2 pumps run and 1 standby. H = 80 m, v = 1.5 m/s
- different of elevation from the pump to the raw water tank: + 5 m
- underground pipeline, we are oriented using material HDPE, size DN 560 with pressure nominal PN 12.5(in economic terms)
- pipeline length: ~15 km
Owner required us to determine and prevent the surge pressure(or water-hammer, transient in other word as i know) affect. Our design sub-contractor submitted us the surge pressure calculation with result about 23.5 bar. The problem is we cant evaluate their calculation is correct or not; how to control the surge to not exceed the design pressure by more than 10%(require by ASME B31.4) to ensure the using of PN 12.5 pipe .
i found in our forum the handbook "Fluid transient in pipeline system", a helpful document and try to research base on it and some relevant AWWA, ASME codes but i really lack of actually experience in order to fix this issue. Please share your knowledge about the water pipeline in any aspect especially regarding to determine surge, protective equipment to control surge pressure.
Thank you for your kindly attention and sharing.

[Abo Khaled]

You can see the following:

1. See AWWA M55 for PE piping design and installations for calculating the surge and transient pressures.
2. Use soft starters for drive the pumps like variable frequency drives.
3. Use pressure relief valves on the pumps discharge side to water source side and many points of the line or network (lower points) and air release on the higher points.
4. The pressure relief valve setting shall be around the shutoff head of the pumps and less than any surge or transient pressure values.
5. Use expansion vessels to absorb part of the transient pressure beside pumps and lower points of the line or network.
6. Use Motorized valves to shut off valves to close smoothly during any shutoff or emergency.
7. Use soft seat (or spring action check valves) on the discharge side of pumps.
8. Coordinate pumps operation with motorized valves operation ( Motorized valve shall open after pumps operation and shutoff smoothly after pump stop).
9. Coordinate pump operation VFD with motorized valve operation i.e. pump partial supply shall be coordinated with partial opening of the motorized vale until the full opening, all flows at constant pressure.
10. See this book also water transmission and distribution AWWA (I did not have the book) on google book.

Greetings

Abo Khaled

[convitco]

thanks Abo Khaled. i hope you will continue help me on my next stage.