SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I'm looking for some creative ways to expand my current system. I want to add 8-10 valves to my system by extending my current trunk line. My current system uses a pump for the water supply and has two Orbit 12-station timers located at the same location. The end of my trunk line where I want to expand the system is 300 ft from the timers and 400 ft from the pump, so I'm trying to do this without running any wires back to either the timers or the pump. I have two valves installed in the current system that I am not using and one of them is near the end of my trunk line.

The best approach I've been able to come up with is to install a new timer near the expansion, which will be a long distance from the existing timers and would not be connected to them or the pump. I would set the new timer to run the new valves and use one of the unused valves in the existing timers to run the pump. I will need to be careful to open the valves with the new timer before starting the pump with the existing timer or I'll run the risk of damaging the pump by running it without any valves open. My main concern is the new timer will stop functioning (circuit breaker trips for some reason) and the pump will start without any valves open. I'm looking into perhaps putting a pressure relief valve on the trunk line near the new expansion to open if the pressure exceeds the expected operating pressure with the valves open, but I don't know if I could get a sufficient volume of water through it to really protect the pump.
I'd appreciate any ideas on how to do the expansion better or how to protect the pump against a new timer shutdown.

Thanks,
Mudman