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…

Pilot project at Niland, CA

Solid salt beds forming

in crystallizers

…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 1Concentrator

Pond 2Concentrator

Pond 3

Solid salt

ponds

Water volume

Concentration

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

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

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

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

Pond 1 Pond 2 Pond 3 Pond 4 Pond 5 Pond 6 Pond 8 Pond 9 Pond 10

5 foot

10foot

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

1001.1

25

1.1

30

1.2

53

1.2

69

1.2

98

1.2

51

1.2

78

1.2

76

1.2

85

1.2

99

1.3

10

1.3

11

1.2

90

1.2

91

1.2

85

1.2

93

1.3

18

1.2

97

1.3

23

1.3

26

1.3

19

1.3

32

1.3

40

Perc

en

t

EntrainNaClCarnaliteEpsomSaltCake

Entrain Brine

NaCl NaCl

Carnalite KCl*MgCl2*6H20

Epsom MgSO4*7H20

SaltCake Na2SO4

Growth Rate

of SaltTotal 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 non-

proprietary, and is available for

review by any interested parties.

Design parameters include differences in

seasonal performanceYield: Cubic Feet Brine per Acre

-

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

CF In

To Crystal

To bittern

Salt Production in Crystalizers and MgSO4 Pond expressed

as TDS Tons per Acre of Concentrator

-

10.0

20.0

30.0

40.0

50.0

60.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

-

10.0

20.0

30.0

40.0

50.0

60.0To Crystalizer

Discharge

Salt Formation

Bittern Salts

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

Exposed Organisms

• American avocets

• Black-necked stilts

• Curlews

• Plovers

• Ducks

Risk Characterization

Food

intake

Water

intake

Sediment

intake

Total

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.