The overall layout of this system seems unusual. Not necessarily bad, just unusual. I think this question deals more with the control system. It seems that the 24/7 chiller has been set up as always the lead unit. A drawing of this system would be useful, as well as a synposis of the control scheme. In the absence of a full description, it will be difficult to suggest alternatives.

Designing the system with the pumps at the top, especially 45 meters up, makes cavitation a concern. a loss of pressure in the the system could result in damage to the pumps. additionally, the extra pressure needed to avoid cavitation, is added stress on the heat exchanger located in the highest pressure area of your system.

if you get to design the system, why not put your cooling tower 45 meters upin positin above your heat source. keep your condensor water pumps on the ground and any other pumps as low as possible in the system.

Perhaps you could make use of natural circulation for the base load, now that your heat source is located below your cooling tower....

benbenben