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CITY OF SANTA ANA Well No. 32 Nitrate Miliaation and Rehabilitation Study 3. Pressure surges will be created as the ground water discharge is diverted from Garthe Reservoir to the distribution system. In order to mitigate pressure surges the following will need to be considered: Surge pressure anticipator valve to discharge to the waste to discharge pipeline A surge tank if the pressure fluctuations are so severe a surge anticipator valve does not satisfactorily mitigate the fluctuations Type of valves used for transitions valve — A valve made to throttle such as a ball or plug type valve — Motor operated valve electric actuator with valve opening and closing speed control 4. The line to Garthe needs provisions to keep it full at all times. • Goose neck at the Garthe reservoir site A pressure reducing /sustaining valve located at the Garthe reservoir site (if back pressure is also required to keep the pump operating on its curve) 5. A variable frequency drive should be considered for control of the well, maintain a constant discharge pressure of 65 psi. This will allow the pump to discharge between 800 gpm and 2,700 gpm before locking on a speed curve. This may allow the City to operate the well for longer durations instead of shutting off at high discharge pressure due to low system demands as would happen with a constant speed pump. 6. Pipe sizing based on: Maintaining a velocity of approximately 5 feet per second, which is an industry standard and recommended for pumping practice. This results in a 16 -inch diameter pipe Utilizing the pipe itself to increase headless so that a pressure sustaining valve is not required but at the same time the pump stays on its pumping curve. A 12 -inch pipe would result in an increase of headless and keep the pump on the pump curve. The resulting velocity in the 12 -inch pipe is approximately 9 feet per second. This is velocity is high compared to the 5 feet per second that typically governs this type of application. However, it is considered reasonable as the use at this velocity is infrequent and temporary (only during well start-up) 7. A provision for routine flushing schedule of the fill line to the Garthe reservoir site will be required to mitigate the potential of the stagnant water losing its chlorine residual and causing a water quality issue. Alternative 2 — Fill Garthe Reservoir 1. Well pump horsepower of 150 hp with a design flow rate of 2,500 gpm. 2. The line to Garthe needs provisions to keep it full at all times. Recommend using a gooseneck similar to what is constructed at the Garthe site to keep the other well fill line full. 3. Results in the ground water being pumped twice; once to storage and then a second to the system. 4. Surge provisions will not be required as the ground water will be pumped directly to storage. 5. Pipe sizing based on maintaining a velocity of approximately 5 feet per second which is an industry standard and recommended for pumping practice. This results in a 16 -inch diameter pipe. 6. Specific pump control is not required (i.e. a variable frequency drive is not required). P.N00599\00W]Egmna,i,\05N_ We11- 32- Nit,mt Mitj,fl Omit R,.M021w done -8- TETRA TECH 251 -26