FINAL REPORT Evaluation of Seawater Desalination Projects ...

EVALUATION OF SEAWATER DESALINATION PROJECTS
PROPOSED FOR THE MONTEREY PENINSULA
In addition to these information gaps, the most significant water quality concerns associated
with the MBRSDP involve the diverse systems owned by the Pajaro/Sunny Mesa
Community Services District (P/SMCSD) that could potentially receive water from the
proposed seawater desalination plant, as well as other systems that could purchase the water,
which have yet to be identified. 32,33 The CDR indicates that the water produced by the
seawater desalination plant will be compatible with the water in the distribution systems to
which it is delivered; however, with customers not yet identified and a variety of disparate
water qualities among the systems owned by the P/SMCSD, this claim cannot be
substantiated. If the water quality is even moderately different among the various systems to
which the desalinated seawater would be delivered, it may be infeasible to treat the
desalinated water to match that of the receiving waters of each system for aesthetics, residual
disinfection, total dissolved solids (TDS), and corrosion control. Moreover, additional pipe
loop and/or coupon testing 34 may need to be conducted for the piping in each receiving
system. If the custom post-treatment conditioning and corrosion testing are not conducted as
a component of the MBRSDP, then any system purchasing desalinated seawater from the
P/SMCSD would have to assume responsibility for these project elements, effectively
increasing the cost of water to the respective ratepayers. This cost, as applicable, should be
factored into the overall cost of desalinated seawater in addition to the purchase price from
the P/SMCSD. 35
The CDR provides discussion of redundancy and peak flow provisions in the design. At
average flow the RO has five duty and one standby train. Similarly, redundancy of the
product pumping facilities is provided. It would appear that a sound redundancy approach is
being applied system wide.
4.3 Sand City Desalination Project (SCDP)
Both the Final Phase 1 Technical Memorandum 36 and the Board Review Draft
Environmental Impact Report (EIR) 37 explicitly indicate that the combination of sand
32 Monterey County Local Agency Formation Commission, North County Municipal Services Review (Revised
Final Draft), February 2006.
33 “PUC OKs Water Systems Sale – Alisal Water Corporation Ordered to Sell Them,” The Salinas Californian,
May 16, 2006.
34 Pipe loop and coupon testing are used to determine the corrosion potential of the material by exposing a
sample of the pipe or pipe material to the water. Highly purified water can be very corrosive to some pipe
materials.
35 In a June 28, 2006 email, Poseidon Resources stated that product water quality control is critical to the
success of the MBRSDP. It intends to follow protocols developed as part of comprehensive studies developed
for other California Poseidon Resources desalination plants for the MBRSDP. No information regarding the
previous studies conducted by Poseidon Resources was provided for the analysis conducted in the report.
36 Camp Dresser & McKee, Monterey Peninsula Water Management District, Monterey Peninsula Water
Supply Project Alternatives – Final Phase 1 Technical Memorandum, March 2003.
Monterey Peninsula Water Management District 4-5