SALTON SEA SOLAR PONDS PILOT PROJECT Agrarian Research 162 East Line Street Suite E Bishop, CA 93514 Under contract to:
Goal of Salinity Management Stabilize (or reduce slightly) the salinity of the Salton Sea by permanently removing from the Sea water all the salt that enters the Sea annually through inflowing water Manage and stabilize Sea elevation through selective removal of excess water
Scientific Goals of the Pilot Pond Project Establish the evaporation rate from the brine Determine the leakage rate from unlined ponds Develop a brine concentration path that will determine the salinity at which the Salton Sea brine begins making solid salt, and which will define the chemical composition of the bittern Determine the annual growth rate of the salt
Additional Goals of the Pilot Pond Project Develop cost-effective strategies for design, construction, operation, and maintenance of a salt removal facility Allow for storage of the salt removed in an environmentally benign fashion Conduct research regarding any potential environmental liabilities Public education
WHY DO A PILOT PROJECT? On-the-ground experience Specific data for design Biological monitoring Public education and stakeholder buy-in
Pilot Project demonstrated feasibility in field Solid salt beds forming in crystallizers Pilot project at Niland, CA
developed data with laboratory experiments, Accelerated evaporation of brine in the laboratory resulted in reliable data on brine chemistry and salt precipitation Evaporation data were collected on site, as well as collection and analysis of solid salt samples from the ponds
and created a laboratory for biological monitoring.
GOAL Stabilize (or reduce slightly) the salinity of the Salton Sea by permanently removing from the Sea water all the salt that enters the Sea annually through inflowing water Removal of salt from the Sea is accomplished by pumping Sea brine into a series of evaporation ponds that concentrate the brine to the point where solid salts precipitate Concentrator Pond 1 Water volume Concentration Concentrator Pond 2 Concentrator Pond 3 Solid salt ponds
Scientific data are needed to develop an optimum design for solar ponds Evaporation rates Leakage rates Characteristics of feed brine Brine concentration path
Evaporation rates 12.0 11.0 10.0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec FW 0.135 0.980 4.000 6.250 Normal year evaporation (inches) at various concentrations (expressed as percent magnesium)
Leakage rate Leakage rate from infiltrometer Leakage Inches/day Avg 0.032 Max 0.042 Min 0.022 Change in Depth in Inch/Month (Feb to November ) piezometers 5 foot 10foot 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00 Pond 1 Pond 2 Pond 3 Pond 4 Pond 5 Pond 6 Pond 8 Pond 9 Pond 10
Feed brine composition Feed Brine (in weight percent) SG Be Ca Mg SO4 Cl K Na 1.035 4.9 0.09 0.14 1.03 1.79 0.06 1.24
Brine concentration path 0 10 20 30 40 50 60 70 80 90 100 1.125 1.130 1.253 1.269 1.298 1.251 1.278 1.276 1.285 1.299 1.310 1.311 1.290 1.291 1.285 1.293 1.318 1.297 1.323 1.326 1.319 1.332 1.340 Percent Entrain NaCl Carnalite Epsom SaltCake Entrain Brine NaCl NaCl Carnalite KCl*MgCl2*6H20 Epsom MgSO4*7H20 SaltCake Na2SO4
Growth Rate of Salt Total salt deposition in crystallizers is about 1.5 feet of mixed (dominated by NaCl) salt per year
Develop cost-effective strategies for design, construction, operation, and maintenance of a salt removal facility
From the scientific data, Agrarian developed a model that generates a pond design specific to the brine, climate, and soils. This design is for a module that would remove 1 million tons of salt from the Sea
Agrarian s model was developed from equations that are standardized in the salt industry, and which we validated with literature and calibrated in the field. The model is nonproprietary, and is available for review by any interested parties.
Design parameters include differences in seasonal performance 45,000 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000 - Yield: Cubic Feet Brine per Acre CF In To Crystal To bittern Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Salt Production in Crystalizers and MgSO4 Pond expressed as TDS Tons per Acre of Concentrator 60.0 50.0 40.0 30.0 20.0 10.0 - To Crystalizer Discharge Salt Formation Bittern Salts Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 60.0 50.0 40.0 30.0 20.0 10.0 -
Pond systems with optimum yield can be designed using the data generated from the pilot pond project. Such ponds can effectively remove salt from the Salton Sea. In-sea dikes increase cost, but can minimize extra evaporative surface. In-sea construction was utilized at the Great Salt Lake production facility
Allow for storage of the salt removed in an environmentally benign fashion Solid salts can be stored as landfill, making shallow, low pyramids capped with soil. This strategy is similar to that used for mine tailings. Original salt bed First lift Second lift
Solid salt characteristics may make it possible to construct dikes on top of solid salt, resulting in cost savings
Conduct research regarding any potential environmental liabilities
Biological monitoring is being conducted in the ponds by Tetra-Tech What contaminants are present? What organisms are exposed to the contaminants? How does the exposure occur (food, water, and sediment intake)?
Contaminants Metals: elevated ones are boron, copper, nickel, selenium, and zinc Pesticides: analyzed ones are 20 organochloride compounds PCB s: analyzed ones are 8 aroclors
American avocets Black-necked stilts Curlews Plovers Ducks Exposed Organisms
Risk Characterization Food intake Total Water Sediment intake + + = = intake intake Toxicity value Risk Potential risks will be assessed by TetraTech with standard formulas
Public education and stakeholder buy-in Visits to the ponds by members of the public and the press occur at least 2-3 times per month, and serve to educate the public about on-going projects relating to active initiatives for Salton Sea recovery
Value for Public Relations and Research Frequent visits to the ponds indicate continued public interest in activities being conducted by the Authority for Salton Sea recovery Biological monitoring can be on-going, increasing confidence in the results
CONCLUSIONS Salt can effectively be removed from the Salton Sea using solar evaporation ponds The data inform a model that predicts with confidence the optimum design for a large scale project There are no obvious environmental liabilities associated with evaporation ponds
Project scientific goals have been met but public relations and monitoring values may continue.