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
• Tier 2 (2501-10,000 gallons): $5000/AF
• Tier 3 (over 10,000 gallons): $7200/AF
[4] Santa
Catalina Island Final Municipal Service Review, Prepared by Burr
Consulting, May 4, 2004, p. 45.
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