I am reviewing a big water pump station with the main suction and delivery steel pipes of 2000 mm (yes 2 meter)and 1400 mm respectively. There are five pumps in parallel and take their suction lines as branches from the mail suction line.

I asked for an air valve at the end of the main suction line (right before the pipe cap)and another at the beginning of the main delivery side, again before the cap. Now the designer has returned with the answer that there is no need for these valves as there are air vents on the pumps.

I have never seen a water pump station without these A.Vs before. I am concern for the filling and the proper air release especially at the pipe dead ends. I'm also concern for the negative surge at the discharge side and the A.V need.

looking to AWWA M11 manual, there is a recommendation to install air valves on the discharge of pumps. So here's the question:
Any other reference or standard to fortify my recommendation for having these valves?

Rather than looking for a source to backup your arguments, why not look for a reason to have them, or not.  Its more interesting than looking for backups to arguments that are only baased on a "suggestion" and may not have any other legs to stand on.

I would assume that the pump vents would be sufficient for priming and starting and the air valves were only suggested for ease of remote autostart when pumps were without automatic vent valves, or no operators were present to vent manually.

Once the start question is decided, I would tend to only place air valves where air valves would be necessary.  Offhand, I would think that air valves might have more typical need on the pump suction lines, as you may not have control of the take source and air may or may not be present, and air through the pump would also reduce efficiency.  Once the air is removed at the suction, why would you need air valves on the pump discharge, provided that vents were there to handle priming.

Now we're getting somewhere.

Of course, if there is a way to trap air in the suction line, it would need to be vented somehow, either manually, or by some other means.  

Surge vessels 150 meters away?  You probably have more surge volume in your piping than in the vessels themselves.  That's a fair piece away with a lot of fluid mass in there that needs to be accelerated too, which will tend to slow down the release of any surge pressure in your discharge line.

Are they surge relief vessels (one way flow), or are they surge vessels (two-way flow)?

The discharge line: 2m diameter. Will it be designed for full vacuum?  If not, DEFINITELY use a vacuum breaker valve in the discharge line.  You will most likely get a complete vacuum, ie. vapor pressure remaining only, surge when the pumps trip.  If the surge vessels are full, you might could take water back from them to eliminate that negative pressure, or perhaps only from the lines going to them would be sufficient, in place of letting in air through a vacuum breaker valve.  Your surge analysis should tell you if you can or not.  Other than that, please have someone that knows what the surge analysis means, not just a "data entry clerk", doing the analysis.  Ask for some hard evidence of experience, and/or some good questions.

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