El Toro Water District Disinfection System Improvements

Laguna Hills, CA


The El Toro Water District (ETWD) existing 2-million-gallon and 3-million-gallon potable water tank reservoirs had difficulty with chlorine residual due to temperature stratification. ETWD contracted PACE to design new tank mixing systems with a residual sampling system, a liquid chemical injection system and storage facility, and a new building with automation and site security. Civil, mechanical, electrical, and controls design plans, specifications, and cost estimates were produced for construction.


PACE evaluated numerous mixing equipment manufacturers and ranked each manufacturer based on several criteria, including capital cost, mixing rate, and energy consumption. The tank mixer chosen was an external pump, which is easily accessible when the system requires maintenance. The high mixing rate of 7,500 gallons per minute mixes the tank within 12 hours and features built-in chemical monitoring.


PACE provided calculations for disinfection storage requirements, as well as a process flow diagram for routing of flows of water, chemicals, analyzer lines, and the flow for mixing. The 300-square-foot liquid chemical storage facility houses a 500-gallon ammonium hydroxide tank and a 2,000-gallon sodium hypochlorite tank.


Key Features:

  • New storage facility design
  • Automation and site security
  • Calculations for disinfection storage requirements
  • Liquid chemical injection system
  • Residual sampling system
  • New tank mixing systems

El Toro Water District

Water Infrastructure