The San Diego County Water Authority (Water Authority) is the regional water wholesaler
responsible for ensuring a safe and reliable water supply to support San Diego's $130 billion
economy and three million residents. The Water Authority imports 75 to 95 percent of the water
used in the region. The Water Authority's 2030
Regional Water Facilities Master Plan indicated an immediate regional need for an additional 50
to 100 million gallons per day (mgd) of treatment capacity. The Water Authority does not own or
operate water treatment facilities and relies on Metropolitan Water District of Southern California
(MWD) and its member agencies to supply all of the region's treated water demands.
Approximately 45 percent of all imported water is treated and supplied by MWD and the
remaining is supplied by member agency water treatment plants (WTP). Multiple studies
indicated the most effective option for additional regional treatment capacity is to build a new
WTP at the Water Authority's Twin Oaks Valley (TOV) site in northern San Diego county.
The Water Authority plans to implement the TOV-WTP using the design-build-operate (DBO)
procurement method. The type of WTP being implemented, conventional or membrane, will not
be specified in the request for proposals for the project. Therefore, the Water Authority
developed conceptual designs for the WTP to serve as a basis for the California Environmental
Quality Act permitting and included development of budgetary cost opinions for comparison to
DBO bids. They will also serve as a resource for the DBO entities bidding for the project.
Proposed conceptual designs using both conventional and low-pressure membrane technologies
were prepared for the 50 mgd expandable to 100 mgd WTP. To provide adequate information to
potential bidders of this project, the conceptual designs were proposed to satisfy the target water
quality goals for the facility. The conventional design included ozone for primary disinfection
and taste and odor removal. The membrane design included granular activated carbon for taste
and odor removal. The proposed designs indicate that the processes are very comparable with
respect to cost and can meet equivalent water quality goals. However, the membrane treatment
process may be capable of providing a better barrier against microbial pathogens. The Water
Authority is conducting pilot-scale testing of low-pressure membrane treatment processes, with
and without pretreatment, to evaluate its feasibility for this project.
This paper, based on the information developed for the conceptual designs, will present a
comparison of cost, ability to meet water quality goals, potential for future expansion, and other
key criteria. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 240 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 19 |
| Published : | 11/15/2004 |
