There are a number of problems with the proposed siphon control system. This is not really a good application for a siphon either. A siphon system should be used when you want to water to flow continuously for irrigation type projects.
1. It seems that you are wasting 10 meters of static head with this scheme by placing the sump at the bottom of the slope. If you are pumping 12 hours per day, that would cost an additional $4-5,000 per year in energy costs. That means that you are wasting 20% of the power cost.
2. Your discharge line is oversized. The pump is shown as 60 l/s and you only need a 250 mm pipe to carry that flow rate.
3. It seems that submersible pumps are proposed from the schematic. This is not a good application for submersible pumps. Submersible pumps are also somewhat less energy efficient than other pumps. Submersible pumps are more commonly used on sewage, not water treatment applications.
4. How do you propose to keep the sump from overflowing? If the valves fail, the sump is going to overflow.
5. Is it possible that the sump is located in a flood zone? If the area floods, will the sump be contaminated? The electrical components would have to be mounted above flood level.
6. The valves SCV-1 and SCV-2 will not function as planned because the operating water head is so low. Throttling valves should be sized such that the flow rate is within the valve’s optimum operating range.
7. Steel piping is not going to stand up to the corrosive effects of the water in this application. You will also be susceptible to MIC (microbiologically influenced corrosion). You need disinfection as well.
8. Why not put the pumps at the top of the slope?
You need to carefully evaluate other water intake structures. Nobody would build a siphon structure like this.
