Irvine Ranch Water District’s (IRWD) Turtle Rock Zone 3 Reservoir (TR Z3 Res) is located in Irvine and supplies water to the surrounding Turtle Rock neighborhood and to the Zone 3 to 4 Pump Station (TR Z4 PS), which serves the uppermost portion of the neighborhood. IRWD has experienced degraded water quality at the TR Z3 Res due to nitrification caused by the loss of chlorine residual, excess free ammonia, and low water supply turnover. Currently, IRWD doses chlorine and ammonia at the Turtle Rock Zone 1 to 3 Pump Station to reduce nitrification in the system but this process is susceptible to chemical precipitation within the pipe where the chemical is injected necessitating multiple replacements of the injection pipe.
This project aims to improve the water quality in Turtle Rock Zone 3 and Zone 4 by upgrading the mixing system inside the TR Z3 Res and constructing a chloramine booster station at the reservoir similar to the chloramine booster stations that are in service at multiple reservoirs throughout IRWD’s potable water system to address the nitrification and in-pipe chemical precipitation issues.
LEE + RO’s design scope includes preliminary design, final design, and bid phase support services.
The design improvements include:
- Chloramine booster station building complete with chemical storage for 12% sodium hypochlorite and aqueous ammonia (19% vs. 29%), chemical metering pumps, chlorine analyzer equipment, reservoir mixing equipment, and related electrical, instrumentation, and control equipment
- Evaluation of potential alternative locations for the station
- Evaluation and recommended improvements to provide adequate mixing of the existing reservoir
- Performing Computation Fluid Dynamics (CFD) analysis to determine the optimal mixer size and location
- Developing a chemical dosing control strategy based on chlorine residual
- Evaluating the existing power supply and identification of required electrical improvements
- Designing the instrumentation and control system for the new chloramine booster station, including SCADA connection
- Addition of sewer service to the new chemical containment drainage system to facilitate drainage for routine cleaning or in the case of a chemical spill
- Providing access to the reservoir from the chloramine building
