Developing Brackish Water Desalination in the San Francisco Bay Area

CA/NV AWWA

Annual ConferenceOctober 1, 2013

Strategies for Developing Water Supply Projects

1. Use Less, Conserve More

- By 2035, conservation savings are projected to be

equivalent to the water needs of 450,000 households

2. Recycle and Reuse

- By 2035, use of recycled water is projected to free up

drinking water supplies for 180,000 households;

other non-potable reuse is also being developed

3. Acquire New Supplies

- Focus on regional partnerships

- Maximize use of existing facilities/assets (unused

capacities)

2

EBMUD

CCWD

SFPUC

Zone 7

SCVWD

48,000 acre-feet

200,000 people

330,000 acre-feet

1.8M people

300,000 acre-feet

2.6M people

200,000 acre-feet

1.3M people

120,00 acre-feet

500,000 people

A partnership between

Bay Area’s 5 largest

water supply agencies.

Bay Area Regional Desalination Project

Together, our

agencies serve over

5.6 million residents

and businesses in the

Bay Area.

3

Study Site: East Contra Costa County

Mallard Slough site in East

Contra Costa (ECC) selected

for Pilot Test/further analysis.

Benefits of Mallard Slough:

• Brackish water source

- Less power

- Less cost

• Permitted CCWD water intake

(Mallard Slough Pump Station)

- Existing intake facilities

(w/permitted fish screen)

• Ability to connect to CCWD or

EBMUD networks

4

San Francisco Bay Water Salinity (26,000)

Pacific Ocean Salinity (34,000)

Brackish Water Source: Mallard Slough

5

Drinking Water Standard (1,000)

Mallard Slough

Site Salinity

Starting Assumptions for Analysis

Facility

• Produce up to 20 MGD of desalinated water at Mallard

Slough (up to 25 MGD from Mallard Slough)

Operations

• Year-round operations at full capacity (with no April

diversions); SFPUC taking up to 9 MGD and Zone 7 taking

up to 5 MGD every year

• Storage available at Los Vaqueros via exchange with CCWD

• Optimize use of existing facilities:

− Direct connections to EBMUD, CCWD

− Wheeled through EBMUD system to Zone 7, SFPUC, SCVWD

CCWD

6

Regional Setting

7

ECC Site

Zone 7

Intertie

Los Vaqueros

Reservoir

Hayward

Intertie

Questions Agencies Need to Answer Before

Deciding to Proceed to Next Step

• What are the potential Delta water quality

and water supply impacts?

• What are the potential impacts to fisheries?

• Are there opportunities to optimize the project

by using storage in Los Vaqueros?

• What are the Greenhouse Gas emissions

and what can we do to mitigate them?

• Does EBMUD have the capacity to deliver

water to partner agencies?

• What are the full costs to each agency?

Greenhouse Gas

Analysis

Storage

Optimization

Delta Modeling

Hydraulic

Computer

Modeling

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DELTA MODELING STUDY(Storage Optimization)

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Delta Modeling: Water Quality & Supply

• Findings:

- Modeled ambient water quality changes

are <0.25% in existing and future conditions

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Brine Blending with Central Contra Costa Sanitary

District (CCCSD) Effluent

0

2,000

4,000

6,000

8,000

10,000

12,000

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Ambient Water CCCSD Effluent Combined

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Brine Blending with Central Contra Costa Sanitary

District (CCCSD) Effluent

0

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6,000

8,000

10,000

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Delta Modeling: Fisheries

- Sensitive Fish Species are present in

the MSPS vicinity.

- Applied a DWR regional-scale

computer model to predict larvae

entrainment

Findings:

- Entrainment at BARDP was less than

0.5% of total particles released

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Storage Optimization

Findings:

• Storage increases reliability and dry year

supplies

• With Storage, the project delivers 84%

of drought year partner demands

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GREENHOUSE GAS STUDY

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Delivery Alternatives Analyzed

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225 85 1,250-1,800 100 600-1,500 kWh/AF

2,260 - 3,700 kWh/AF(1,660 – 2,210 kWh/AF without EBMUD conveyance)

Energy Use of the Desal Facilities

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0

1000

2000

3000

4000

5000

6000

7000

Average Annual Total Energy Use Per Household

Average Refrigerator (80

Watts)

Household Desalinated Water Supply (100% of

Supply)

Household Desalinated Water

Supply (8% of Supply - Zone 7)

6600

701

1314

105

An

nu

al

En

erg

y U

se

(k

Wh

/Ye

ar)

Comparison of Energy Consumption

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GHG Reduction Goal Examples

Carbon-Free: offset all GHG emissions (9,240 MT CO2e/yr)

No Net Increase: offset the difference between GHG

emissions with and without the BARDP (5,810 MT CO2e/yr)

Estimated Costs for GHG reduction: $10 to $50/AF

CCWD 5% EBMUD 11%

SCVWD 12%

SFPUC 46%

Zone 7 26%

Partner

Projected Annual

Indirect Emissions

(MT CO2e/year)

30-Yr Average

CCWD 470

EBMUD 1,060

SCVWD 1,070

SFPUC 4,280

Zone 7 2,360

Total

Indirect

Emissions9,240

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HYDRAULIC MODELING STUDY(Wheeling Cost Estimate)

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EBMUD System - Key Wheeling Facilities

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Hydraulic Modeling Results (MGD)

EBMUD can deliver (normal years, 2040 conditions):

- 10 mgd to Zone 7: 95% of the time (peak day is exceeded 20 days in a year)

- 20 mgd to SFPUC/SCVWD: 90% of the time

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20 MGD Desalination Facility at MSPS - (2013 $/AF)

PRELIMINARY SFPUC Zone 7 SCVWD EBMUD CCWD

Mallard Slough Pump Station $125 $125 $125 $125 $125

Desalination Facility $900 $900 $900 $900 $900

Wheeling (EBMUD) $420 $360 $420 -- --

Hayward Intertie Costs $60 -- $60 -- --

GHG Reduction $50 $50 $50 $50 $50

Total ($/AF) $1,555 $1,435 $1,555 $1,075 $1,075

Note: Does not include cost of fisheries mitigation (??), or storage in LV ($100/AF)

Cost Estimates – $/Acre-Foot

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Questions?

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