Project Description

The San Diego County Water Authority is building its first regional water treatment facility in Twin Oaks Valley, located north of San Marcos. The Twin Oaks Valley Water Treatment Plant will produce up to 100 million gallons of treated water per day -- enough to supply up to 220,000 typical four-person households each year. Currently, San Diego County’s existing treatment plants barely meet the demand for water during warm periods when water use is highest. The new facility will prevent treated water shortages in San Diego County and reduce the region’s reliance on treated water from outside the county.

The Twin Oaks Valley Water Treatment Plant will be one of the largest submerged membrane treatment plants in the world and is attracting the attention of national and international water professionals.

The first treated water from the Twin Oaks plant is anticipated to flow in the spring of 2008.

Why the Twin Oaks Valley Location?

The Water Authority selected Twin Oaks Valley for a new regional water treatment plant for several reasons:

• Water treated at this location can be made available to water users in North County, where the need for additional treated water is the greatest.
• Treated water from the plant at this site can be placed in the Water Authority’s aqueduct system without the need to construct new pipelines or pumping facilities.
• The Water Authority property at this location is large enough for a treatment plant that can produce enough water to meet the region’s expected water demands in the future.
• Having the plant at this location will enable the Water Authority to provide treated water instead of untreated water in an emergency situation. In the event of an earthquake or other disruption in the delivery of imported water to region, the plant in Twin Oaks will deliver treated water to the Water Authority’s emergency water delivery system, avoiding the need to instruct the public to boil water before using it.

Project Schedule

Fall 2006 – spring 2008	Work hours from 7 a.m. to 7 p.m. Monday through Saturday
Mid-September 2006 - spring 2007	Installation of concrete, water pipelines
Spring 2007 – winter 2007	Mechanical and electrical work and equipment testing
April 2008	Water treatment begins
Fall 2008	Landscaping and clean-up activities completed

Location Map

Printable version

Twin Oaks Valley Groundbreaking Event

On Dec. 6, 2005, more than 100 residents, contractors, and staff joined the San Diego County Water Authority at the groundbreaking ceremony at the site of the future Twin Oaks Valley Water Treatment Plant. This facility is the first-ever Water Authority owned water treatment plant located just north of San Marcos. Once completed, the facility will deliver 100-million gallons a day of treated water to the county to help meet increasing demand during warm-weather months, and reduce the region’s reliance on treated water from outside the county.

Program participants included: Maureen Stapleton, general manager; Jim Bond, chairman; Tim Suydam, project manager; Margaret Ferguson, chairman, Vallecitos Water District; Tom Searle, CH2M HILL; and Ben Morris, resident and member of the Water Treatment Plant Working Group. At the conclusion of the event, each attendee received a xeriscape plant as a memento of this important milestone for the Water Authority.

Subcontracting Opportunities

CH2M HILL is currently building the Water Authority's Twin Oaks Valley Water Treatment Plant Design-Build-Operate project. Construction began in January 2006.

For more information on subcontracting opportunities for this project, including upcoming bid packages and prequalification, visit CH2M HILL's SCOOP Website at http://ch2mhillscoop.com.

Publications

Project Fact Sheet

Submerged Membrane Fact Sheet

Twin Oaks Valley View Newsletter

Spring 2008
Summer 2007
Fall 2006
Fall 2005
Winter 2005

 

 

Community Outreach

Letters and postcards to community

• Postcard Update - January 11, 2008
• Grading work Postcard April 2007
• 24-hour Work Notification Letter – November 14, 2006
• Construction Update Meeting Invitation – June 24, 2006
• Construction Postcard - January 18, 2006
• Construction Notification Letter – December 13, 2005
• EIR Approval Meeting Postcard – August 23, 2005
• First Working Group Meeting Postcard - March 23, 2005
• Geotechnical Work Postcard – February 4, 2005
• Sept. 1, 2004 Letter
• July 14, 2004 Letter
• Project Open House Postcard - June 30, 2004
• June 16, 2004
• April 9, 2004

Twin Oaks Valley Working Group
To address concerns raised by members of the Twin Oaks Valley community about the treatment plant’s potential impacts on the area, the Water Authority convened the Twin Oaks Valley Working Group. Members include residents, a business owner and representatives from the Twin Oaks Valley Community Sponsor Group and the Twin Oaks Valley Property Owners’ Association. During meetings with the Water Authority project team, the working group prioritized their ideas for addressing the potential project impacts. The Water Authority incorporated some of the suggestions into the project specifications for CH2M HILL the design, build and operate team for the water treatment plant.

Working Group - Summary Report (November 2004)

Meeting summaries:

• Oct. 12, 2004
• Sept. 28, 2004
• Sept. 14, 2004

Twin Oaks Valley Community Sponsor Group

Meeting summaries:

• Oct. 17, 2007
• Nov. 15, 2006
• Nov. 17, 2004
• July 21, 2004

About Water Treatment

Water from rivers and reservoirs can contain a variety of organisms and inorganic material that must be removed at a water treatment plant before the water is safe for drinking and other uses. Different treatment plants can vary in the specific processes they use, but they generally follow the same basic steps.

Larger particles such as sand, vegetation and other materials must be screened out first, then smaller particles are removed in a separate process. To eliminate organisms that can cause disease or unpleasant odors and taste in water, disinfecting chemicals are added. In many treatment plants, water passes through an additional filtering medium such as sand, gravel, carbon or anthracite, to remove any remaining tiny particles. The last step is to apply an additional, long-lasting disinfectant that will keep water safe and healthy for the days or weeks it may travel through pipelines to reach homes and businesses.

The Water Authority selected the submerged membrane method for treating water at the plant. This method of separating water molecules from contaminants is safe and highly effective in producing high-quality treated water.

Environmental Studies

The Water Authority prepared an environmental impact report for the Twin Oaks Valley Water Treatment Plant to identify and address potential environmental impacts of construction and operation of the facility. The final report was certified by the Water Authority board of directors in spring 2005.

Final Environmental Impact Report

Contact Us
For more information, please call the 24-hour toll-free project information line at (877) 682-9283, ext. 7010 or email CIPinfo@sdcwa.org. Your call will be returned within one business day.