Thursday, April 2, 2015

Catalina Island & Drinking Water

A sustainable, reasonably priced supply of fresh water is the resource most critical to residents, as well as private land owners and developers planning to build an 18-hole golf course, luxury hotels, restaurants and other amenities. Southern California Edison Company's water service on Santa Catalina Island serves 1,923 customers (2005).[1]

            Rainwater is stored in reservoirs throughout the island's interior, which is subsequently purified then piped to the towns of Avalon and Two Harbors. A desalination plant also services Avalon.[2]   Since 1975, most of the island’s interior and 48 miles of coastline have been managed by the Catalina Island Conservancy (Conservancy lands total 88 percent of Catalina Island). This organization is tasked with protecting the island’s biological communities and managing the recreational use of the island.   The Wrigley Reservoir is in the middle of the Conservancy and is surrounded by natural areas.[3]

            Groundwater is relatively clean as it has already been filtered through its natural production process; the groundwater is filtered and chlorinated before being distributed to consumers.  Saltwater used for toilet-flushing and fire suppression purposes is simply filtered as it is not intended to be potable.  Seawater is desalinated using the reverse osmosis principle. After about 30-35 percent of the original saltwater is converted, the balance is returned to the ocean through an outfall. The fresh water resulting from the reverse osmosis process is chlorinated and then pumped into the water mains located just outside the SCE facility.[4]

Reverse Osmosis Membranes

     Southern California Edison and Whitehawk Catalina, Inc. completed construction of a 132,000 gpd desalination plant on Santa Catalina Island in June 1991. The plant produces 25 to 30% of the Island's water supply, including the potable water supply for the Hamilton Cove condominium development.   The desalination plant is located adjacent to SCE's Pebbly Beach Generating Station, and brine is discharged through the station's existing cooling water outfall. Feedwater is taken from two feedwater wells. Product recovery is about 27%. The size of the plant is about 2,100 square feet. The cost of the water produced is about $2,000/AF ($6/1,000 gals).[5]

            Dual pipe infrastructure already exists on Catalina.  Saltwater is employed in the toilet system and other facilities in Avalon.[6]  Unique issues for wastewater treatment include the high salt content of the wastewater resulting from the City’s use of salt water for toilet flushing throughout the system; and very large differences between average and peak flow loadings resulting from the varying tourist population at this popular resort.[7]  The Center proposes to separate the pipe infrastructure and to eliminate the use of salt water in the wastewater system.

            On Catalina Island, in an effort to preserve fresh water, all wastewater in homes is flushed into the sewer laterals and City mainlines using saltwater. It was discovered that the use of saltwater for wastewater purposes leads to corrosion of the laterals. A majority of the laterals were broken or cracked, causing wastewater from the homes in Avalon to enter the groundwater system.[8]

            Desalination. The Center is proposing to arrange for the construction of a new desalination plant.  The new plant will utilize distillation [See Attachment 8] instead of the reverse osmosis process utilized in the current plant. We are proposing to utilize a distillation desalination system that utilizes photovoltaic panels with natural gas backup as the heat source.  This heating system could be supplemented with a biomass to heat and biomass to electricity system.  Biomass will come from clearing brush throughout California to reduce the incidences of wildfires.

            California PUC resolution granting Southern California Edison a 2007 rate increase showed that Catalina Island desalinated water accounted for 25% of total water production in 2005, but desalination accounted for approximately 70% of total electricity usage. The CPUC resolution report noted  that the overall energy intensity (75% local water/25% ocean desalination) of Catalina’s water system is approximately 4000 kwh/AF (acre feet). The CPUC approved a 3 tiered rate, roughly calculated below:[9]

• Tier 1 (up to 2500 gallons): $2000/AF
• Tier 2 (2501-10,000 gallons): $5000/AF
• Tier 3 (over 10,000 gallons): $7200/AF

[1] Water Roadmap, California Public Utilities Commission, Filed December 13, 2005, p. 24
[2] Visiting Catalina Island, History
[3] Geosynthetics, "Reviving the Wrigley Reservoir on Catalina Island."
[4] Santa Catalina Island Final Municipal Service Review, Prepared by Burr Consulting, May 4, 2004, p. 45.
[9] The Oil Drum, "Desalination: Energy Down The Drain," Essay by Debbie Cook, March 2, 2009.

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