STRATEGIES FOR THE
RESTORATION AND ENHANCEMENT
4.2 Alternative 1: Diked Area/Solar Power Generation/Constructed Wetlands
This approach, as depicted in Figure 5, incorporates several earlier proposals with one additional concept and consists of three main components:
1. An enhanced evaporation system (E.E.S.) to reduce and control salinity levels, would be combined with a solar pond power plant to generate electricity.
Such a system was previously proposed by ORMAT, an Israeli geothermal development company. It combined E.E.S. utilizing spray nozzles to "mist" water, thus increasing the evaporation rate while decreasing the necessary surface area, with a power generation system in which solar heated brine evaporates organic fluid which drives a turbine to produce mechanical work which is then converted to electricity.
Cost reductions from the original concept are possible by locating it adjacent to the Salton Sea, utilizing evaporative ponds to concentrate approximately half of the salt brine and thereby reducing the capitol and operating cost of the EES system and clustering the solar ponds so as to reduce grading. The system could potentially be located between Bombay Beach and the Wister Wildlife Refuge.
2.Two diked areas, which would be used to stabilize the elevation of the Sea, would be constructed at the south end of the Sea near the Alamo River and the New River. A third area might be constructed at the north end near the Whitewater River. These areas would help stabilize the Sea's elevation by compensating for withdrawals needed to reduce salinity. In addition, the dikes would reclaim land from the Sea which might then be used for other purposes such as agriculture, wildlife habitat, or water harvesting.
3.Constructing wetlands at or near the mouths of the New, Alamo and Whitewater Rivers would address the pollutants issue. Constructed wetlands utilize natural biological processes to purify wastewater. Water is funneled through aquatic plant systems which absorb and biodegrade organics. Plants will also uptake heavy metals.
4.2.1 Benefits of this Alternative
This combination of diking, E.E.S./solar pond power plant, and constructed wetlands remediates the identified problems at the Salton Sea and provides additional benefits as follows:
a. SalinityThe E.E.S./solar pond power plant has the capacity to lower the salinity level of the Sea to 35,000 ppm in approximately 10 years. This would require pumping approximately 250,000 acre feet of water out of the Sea per year. Assuming historic levels of inflow to the Sea, the surface elevation could drop over 10 feet during this period without diking off a portion of the Sea.
b. Surface Elevation StabilizationThe construction of a diked area would reduce the total volume of the Sea thus compensating for the withdrawal of water to the E.E.S./solar pond power plant. The diked area would also provide a mechanism to stabilize the surface elevation at a drop of about 5 feet from existing levels by providing an area into which water could be diverted from the Sea or in which storm water and/or diverted agricultural run-off treated in the constructed wetlands could be stored to release into the Sea.
c. Pollutant ControlThe constructed wetlands at the mouths of the New and Alamo Rivers would assist in filtering pollutants such as selenium and remove excess nutrients through biological processes. Should constructed wetlands be inadequate to completely address nutrient loading and pollutant issues, other approaches could be explored as adjuncts. Such approaches could include pumping water with high concentrations of selenium into an aquifer to fix the selenium into the soil as selenite under anaerobic conditions. Other potential approaches include pumping water from under high selenium lands, reverse osmosis treatment at selected locations where selenium concentrations are highest, and selectively retiring farm lands where the concentrations of selenium are highest.
d. Additional Benefits
- Up to 15,000 megawatts of power could be generated for sale. This creates not only useful energy, but also a revenue stream to help offset the cost of restoring the Sea.
- Desalination of water may be combined with the E.E.S./solar pond power plant and blended with agricultural return water and utilized for irrigation (utilizing distillation of cooling water). The irrigation water thus saved could be sold to water purveyors for use elsewhere in southern California. This provides an additional revenue source to help offset remediation costs.
- Diked areas might be used to capture storm runoff which could then be treated and sold along with desalinized water.
- Diked areas could also be utilized to create additional wetlands habitat or could be reclaimed for agricultural uses. Lease of this land for agricultural purposes would be another revenue source.
- Dikes could provide access for fishing and other recreational opportunities such as wildlife viewing.
- Wetlands habitat, whether in the diked area or in the constructed wetlands, could be established as a mitigation bank and credits sold.
- Stabilization of the surface elevation would create new development opportunities by eliminating the threat of inundation.
4.2.2 Issues Requiring Additional Consideration
Issues requiring further study include disposal of brine, potential environmental impacts, market demand for the energy produced, and demand for water harvested for sale.
4.2.3 Long Term Management
In exploring ways to address the major threats to the Sea, it is important to also think about the opportunities which are created for long term management. Activities and enterprises made possible by the rehabilitation of the Sea ought to help pay for the costs of remediation and long term management. What are some of these activities and enterprises?
The constructed wetlands would provide expanded wildlife habitat which could increase visitation by birders and others interested in viewing nature. If dike areas were also managed, at least in part, for wildlife habitat, this too could expand visitation. A wildlife viewing area could possibly be established at the northern end of the Sea to augment the viewing areas at the southern end. Restoration and enhancement of a sport fishery would also attract additional visitors. This would encourage state park improvements and could create additional demand for services, including camping facilities, motels, restaurants, etc.
Stabilization of the surface elevation would create opportunities to restore and enhance existing marina/recreation areas at the Sea and potentially create new facilities. Additional residential, commercial, and resort development, including golf course development might also result.
Collectively, these opportunities could lead to the realization of the Salton Sea's tourism potential. Such potential ought to be encouraged and planned for since revenues from these various improvements could help pay remediation and management costs for the Sea.
The development of a comprehensive plan would enable the Authority to evaluate remediation alternatives in the context of longer term goals and objectives, and to identify opportunities created by the rehabilitation of the Sea and the best strategies for capitalizing on them. Accompanying environmental documents would provide a sound basis for decision-making and might function as a program EIR for later project specific planning.
Alternative # 1 Diked Area/Solar Power Generation/Constructed Wetlands