Transcript Document 7331968

Desalination for Marin County
Paul Helliker
General Manager
Marin Municipal Water District
North Bay Watershed Association
April 5, 2007
2-Minute History of MMWD Water
Annual Rainfall: 1879 through 2001
1971
Measure B Fails
1960
Nicasio
1953
1996
Lagunitas Creek
Settlement
1982
Kent Lake
Raised
1979
Soulajule
1992
Measure V
Passes
Kent
1948
Bon Tempe
1977
Richmond
Bridge Pipeline
1991
Measure W
Fails
1918
Alpine
1912
MMWD formed
1976
First Russian
River Imports
1990
Pilot De-Sal
Plant
Current MMWD Supplies
High
cost
Recycled
2%
Russian River
(via NMWD )
26%
Supply will decrease 25%
Reservoirs
72%
Climate
uncertainties
Projected Supply and Demand
Acre-feet
1987 Demand
35000
Current Yield
30000
25000
Future Yield
20000
15000
10000
5000
0
2002
2005
2010
2015
2020
Projected 2020 Scenario
 Current supply deficit:
 Demand increase:
 Projected loss of NMWD
capacity:
 Total projected deficit:
3,200AF
1,560AF
2,300AF
7,060 AF
MMWD Options
 Conservation
–
–
–
–
Remains first choice
Already achieved 25% savings
BMPs implemented and very aggressive tiered rates
Additional reductions may cost more than other options
 Recycling
– Currently have many innovations in place
– Expansion complicated by cost and water quality issues
 Imports
– Endangered species protection limitations
– Least costly now – likely increase
 Desalination
– Reliable supply
– Cost and energy use are major issues
MMWD Plan
– Proximity to infrastructure
– Mix brine with wastewater
in existing deep water
outfall
– Intake water is less saline
and is warmer than ocean
– No power plant impacts
– Public ownership
– Reduce imports
MMWD Desalination
Pilot Program & EIR
- Nine/Twelve month
demonstration and test
- Conventional/MF/UF
pretreatment, 4 Reverse
Osmosis makes
- Chemical, biological
testing of water streams
- Dilution modeling
- Fisheries studies
- Entrainment analysis
Intake Screening
 Designed to meet
Federal and State
criteria for fish
protection
– 3/32-inch openings
– <0.3 fps velocity
– airburst cleaning
 Located at end of
existing 2000-ft pier
 Multiple screens for
full-scale facility
Reverse Osmosis (RO)
Desalination
 Tested four
manufacturers
 Three RO
elements per train
 Initial problems
with non-standard
sizes
 All performed
acceptably – fewer
cleanings with
MF/UF
Bay Fish Sampling
Summary of Results
 Northern anchovy & Pacific
herring common in midwater trawl
 Bay goby, shiner perch common
in otter trawl
 Dungeness crab most common
invertebrate
 Species composition similar to
CDFG sampling
 Spiny dogfish not collected by
CDFG
 Long-term CDFG data can be
used in the environmental
analysis
Pilot Plant Entrainment Study
 Measurement of species
composition, seasonal distribution,
and densities of icthyoplankton,
crab, shrimp, oysters
 Twice monthly for 12 months
 Use Empirical Transport Model,
Adult Equivalent Loss and
Fecundity Hindcast models to
estimate entrainment impacts
E
n
v
i
r
o
n
m
e
n
t
a
l
Estimated Entrainment
Taxa
Pacific
Herring
Total Annual
Entrainment
Annual 2FH
Estimate
Annual AEL
Estimate
ETM:
Pm Estimate
229,061,594
31,396
67,458
0.000625
1,860,969
4,698
3,089
0.000298
northern
anchovy
615,864
40
45
yellowfin
goby
565,866
200
*
unidentified
gobies
N/A
0.000224
Results to Date
 ETM estimates range from 0.02 – 0.06%,
well below sustainable harvest level of 3040%
 No northern anchovies in source water –
no ETM estimate
 No salmon, steelhead or sturgeon larvae
were collected
Brine Discharge Analysis
 Analyzed near- and far-field dilution of
brine in sewage effluent
 Brine flows stable, up to 15 MGD
 Sewage highly variable flow: 2 – 100 MGD
 Near field dilutions average 200:1, min. of
9:1
 Far field dilutions in San Rafael Bay of
1500:1
Size of the Initial Mixing Zone
Worst Case:
650m x 250m
Mean: 30m x
15m
Brine Mixture Bioassays
 Acute bioassays on mysid
shrimp, topsmelt, marine algae
at 79%, 27% and 5% brine
– No significant impacts
 Chronic bioassays on giant
kelp, bay mussel, inland
silverside at 79% and 27%
brine
– No significant impacts under
EPA protocol (correct salinity)
– Sublethal impacts for highbrine mix
– No major differences from
sewage effluent alone
Water Supply Analysis
 Testing for:
– 100 Regulated compounds or compounds that require
monitoring
– 250 non-regulated compounds
– An additional 100 non-regulated compounds specific
to SF Bay (incl. flame retardants, algal toxins)
– E-screen bioassay
 6,000 Data Points to Evaluate Water Quality
and Treatment Performance
Desalinated Water Quality Results
Detailed List of Constituent Sample Results Available
Constituents
Maximum
Contaminant
Level (MCL)a
SF Bay
Watera
Desalinated
Watera
Existing
MMWD
Sourcesa
Sodium
N/A
7,100
21
18 – 20
Chloride
250b
12,000
20
8 – 21
Total Organic
Carbon (TOC)
2c
0.86
ND
1–2
Boron
1d
2.3
0.2
ND – 0.28
0.00005
0.00002e
ND
ND
0.002
ND
0.0003e
ND
Ethylene
Dibromide
Mercury
a - ppm
b – Federal Secondary (aesthetic) Standard
c – based on MMWD source water quality
d – CA DHS notification level
e – 4 of 5 samples tested non-detect
Energy for Desalting Seawater is Similar
to Common Appliances
On average, MMWD households use 270 gallons of water per day
81 Watts
At 7.15 kWh/1000 gal
seawater desalination
requires only 1.9
kWhr/day of power to
produce 270 gallons
per day.
1.9 kWh/day
100 Watts avg.
2.4 kWh/day
140 Watts
75 Watts
100 Watts
3.4 kWh/day
1.8 kWh/day
2.4 kWh/day
Annual Energy Use, Million kWhr per
year
Desal would be approx. 0.7% to
3% of Annual Marin Energy Use
1800
1600
1400
1200
1000
800
600
400
200
0
Current MMWD
Energy Use
Desal (Avg
Conditions)
Desal
(Drought
Conditions)
Marin County
Energy Use *
* From California Energy Commission for year 2000
Desal Energy is like an extra
lightbulb in every Marin home
 Average operation would be like an extra
compact fluorescent bulb on all the time
 Drought operation would be like a
standard 100-W bulb on all the time
 MMWD will be considering renewable
power to supply this energy need
Cost of Desalination Option
• Desalination facility: $81-121 million
• Non-construction costs (permitting,
construction management, etc.): $7-10 million
• In-system distribution improvements (Phases
IV and V): $22 - 42 million
Total
$110 - 173 million
Annual operating costs: $4 – 12 million
Normalized cost: $2,433 - $2,023 per acrefoot