PACE was contracted by the City of Anaheim to study and recommend optimal operation of the Walnut Canyon Reservoir, a large 920-million gallon raw water reservoir, and the Lenain Water Treatment Plant. The reservoir is used as a feed source for one of the City’s water treatment plants. Specifically, PACE performed monthly field water quality monitoring and water sampling for dissolved constituents, collected water and sediment samples and measured water and sediment oxygen demands, and constructed a water quality model and databases useful in identifying the reservoir water quality characteristics, such as macronutrients (i.e., nitrogens and phosphorus), iron and manganese release, sulfate reduction, and dissolved oxygen depletion. In addition, PACE conducted rigorous water quality studies including water chemistry analysis, algae counts and identification, and bench-scale water treatment tests during periodic taste and odor events occurred in 2010 and provided the City a series of expert consultation and recommendations on their reservoir and water treatment plant operations.
PACE also developed concepts to improve the current conditions at Walnut Canyon Reservoir including:
- Prevention of foul odor releases during lake turnovers in fall and winter months
- Various treatment alternatives for taste and odor compounds, including algal metabolites (geosmin and 2-MIB) and hydrogen sulfide, generated within the reservoir
- Alternative lake aeration scenarios to prevent stratification and to minimize the bottom dead zones during summer months
- Best management of zebra and quagga mussels proliferation in the reservoir, especially within the water intake structure
- Detailed water chemistry analysis for spatial-temporal lake water quality monitoring
- Chemical and biological analyses for taste and odor management
- Algae quantification and identification
- Macro and micronutrient
- Destruction of odorous hydrogen sulfide (H2S) without purchasing additional chemicals or equipment, but using an exisiting ozonation facility in the Lenain Water Treatment Plant
- A bench-scale study was conducted to determine an optimal ozone-sulfide ratio to achieve sulfide and manganese removal below their secondary MCL or reported odor threthold (both <0.05 mg/L), while minimizing the formation of bromate, a potentially carcinogenic disinfection by-product of ozonation (<0.01 mg/L).
- Dilution of bottom water with the reservoir inlet water to have appropriate sulfide concentration for ozone treatment.
- Water and sediment core analysis for oxygen demand calculations
- DYRESM-CAEDYM hydrodynamic model for reservoir water quality