Highlights:
- A .6 million-gallons-per-day facility, the plant services a population of 200 businesses, 4,000 people, and as many as 40,000 visitors daily
- Work began on the project in 2007 and completed in 2010 at a cost of $5.2 million
- The design-build contract was awarded through a competitive bidding process
- Chosen for the 2012 WateReuse Association Project of the Year Award – Desalination Facility
Challenge
Historically, and as many west coast jurisdictions experience, Sand City, CA has relied on a regional source of supply shared with other municipalities in the Monterey area. However, some of the local aquifer and surface water sources were reaching an overdrawn capacity limit, thus creating challenges for future water supply needs. Seeking to move forward with redevelopment in order to attract new visitors, Sand City’s plans were put on hold based on the supply limitations. This progressive small city then looked at available alternatives that would enable them to secure a long-term, locally controlled, sustainable water supply source for its growing needs.
Approach
Given their coastal location, Sand City decided to pursue seawater desalination. The City’s initial concept was a 0.3 million-gallon per day facility. However, working collaboratively with the Owner, the CDM project team re-envisioned the project with multiple creative options that made it possible to not only double the installed capacity with only marginally higher capital costs, but also substantially reducing permitting timeframes, energy use and operating costs.
The process steps to transform seawater into potable supplies must consistently consider and protect the natural environment; and, the processes themselves are energy and cost efficient compared with alternatives for new water supply. The plant was also built with a “benign by design” principle whereby the byproduct water proved to be of the same salinity as Monterey Bay. For this, and other reasons, the plant received unanimous approval from the California Coastal Commission.
Results
The 166 million gallons produced by the plant have reduced daily withdrawals from the highly stressed Carmel Valley aquifer, which has historically been over-drafted. Energy savings are achieved through high-efficiency VFDs, premium motors, energy-recovery turbines, high-efficiency lighting, skylights, and day-light controls that, in total, save more than 667 tons of greenhouse gas emissions per year, compared with a more traditional facility design, according to energy utility estimates. Isobaric energy recovery devices recover over 95 percent of the energy input into the RO system from residual pressure. The devices, manufactured by Energy Recovery Inc, are the first municipal installation of this U.S. manufactured equipment in the country. The feed water pumping approach at Sand City has achieved an estimated 53-percent reduction in energy use.
In addition, based on 2 years of reliable operation and nearly continual use, the Sand City Coastal Desalination facility has achieved an exceptional record of meeting or exceeding the rigorous performance criteria under which it was permitted. Innovative design elements have achieved estimated cost and energy-use reductions, including 4.9 kWh/gal energy use and production costs of $2,760 per AF. The Department of Public Health and California Coastal Commission, both known as rigorous regulators, have referenced the project’s treatment process as a model for coastal desalination.
Award Winning Achievement:
The Sand City Coastal Desalination Facility was chosen for the 2012 WateReuse Association Project of the Year Award – Desalination Facility. The WateReuse Project of the Year Award recognizes projects whose significance and contributions to the community continue to advance the water reuse and desalination industry. The Sand City Coastal Desalination Facility has demonstrated continued dedication to the water reuse and desalination community, and the WateReuse Association gratefully acknowledges the contributions you have made. The award was presented to City officials at the Annual Awards Luncheon held Monday, September 10, 2012 in Hollywood, FL. The WateReUse Association received a total of 41 award nominations this year, with 5 in the Desal Category.
