managing wastewater in a changing climate
TRANSCRIPT
Managing Wastewater in a Changing Climate
Caitrin Chappelle
Research supported by the California Association of Sanitation Agencies, the S. D. Bechtel, Jr. Foundation, and the US Environmental Protection Agency
April 22, 2019
California’s wastewater sector is at a turning point
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Wastewater management helps protect public health and the environment, is source for recycled water
Shifts in policies, better planning can help sector prepare for drought, changing water demands, climate change
New report based on first-hand information from agencies– Surveyed wastewater managers on experiences before, during,
after latest drought (133 responses) – Focus groups with local and state agencies helped define
challenges, innovations
Drought and changing climate complicate wastewater management
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Reduced indoor water use reduces volumes into treatment plants Shifts to alternative water sources can affect influent quality Lower flows, higher temperatures in rivers and streams will further
stress ecosystems that depend on treated wastewater More “atmospheric rivers” will increase flood risk to treatment
plants, bring unplanned spills Sea level rise will affect wastewater treatment plants on the coast
A shift is needed in how we manage wastewater
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Key Challenges: Maintaining water quality in the
face of reduced indoor water use Making smart recycled water
investments Balancing conflicting objectives
within watersheds
Outline
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Maintaining water quality in the face of reduced indoor water use Making smart recycled water investments Balancing conflicting objectives within watersheds
Maintaining water quality in the face of reduced indoor water use
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Wastewater managers must adapt to:
– Periodic short-term water conservation in response to droughts
– Long-term increases in urban water use efficiency
The unusually warm drought of 2012–16 was a window into the future
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Urban water use rapidly declined during mandated conservation period
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50
75
100
125
150
175
200
225
250
Jun14
Oct14
Feb15
Jun15
Oct15
Feb16
Jun16
Oct16
Feb17
Jun17
Oct17
Feb18
June18
Oct18
Feb19
Wat
er u
se p
er c
apita
(gpc
d)
San Joaquin Valley
Northern California
Statewide
Southern California
Central Coast
San Francisco Bay
Governor'smandate
announced
End of drought emergency declared
Reduced indoor water use led to reduced influent flow, changes to influent quality
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61
85
0 20 40 60 80 100
Change in influent oreffluent quality
Reduced influent flows
Share of surveyed wastewater agencies (%)
Wastewater agencies experienced problems with collection and treatment during the drought
10
6
37
18
19
27
0 20 40 60 80 100
Damaged infrastructure
Processing issues
Increased odor problem
Increased corrosion
Increased solids deposition
Share of surveyed wastewater agencies (%)
Treatment challenges
Collection challenges
Agencies must adapt to long-term reductions in indoor water use
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Long-term indoor water use efficiency will impact amount, quality of influent
Per capita water use is declining, further declines likely as a result of state, local policies
Recommendations for building resilience
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Increase information sharing and coordination with water suppliers
Plan for future droughts Improve understanding of
wastewater system vulnerability
Maintain its current
levels31%
Increase slightly
31%
Increase significantly
38%
“Coordination between water suppliers and wastewater agencies needs to ______.”
Outline
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Maintaining water quality in the face of reduced indoor water use Making smart recycled water investments Balancing conflicting objectives within watersheds
Wastewater is the source for recycled water, a growing water supply
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Reduced influent flows during drought cut into recycled water production
Changing influent characteristics creates challenges
Evolving regulations and state policies will change demand
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
1970 1977 1987 2001 2009 2015
Rec
ycle
d W
ater
Use
(acr
e-fe
et)
UrbanAgricultureGroundwater rechargeOther
Recycled water use is growing
Recommendations for building resilience
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Regional plans for recycled water investments are needed
Focus on flexible recycled water investments
Clovis Water Reuse Facility
Outline
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Maintaining water quality in the face of reduced indoor water use Making smart recycled water investments Balancing conflicting objectives within watersheds
Most plants discharge treated wastewater into inland watersheds
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Adapting to declining water use and meeting increased demand for recycled water may mean less treated wastewater for:
– Environmental water needs– Downstream users
Climate change exacerbates these conflicts
Salton Sea
Recommendations for building resilience
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Identify watersheds vulnerable to changes in wastewater management
Develop science to support management and regulatory decisions
Evaluate tradeoffs caused by the interplay of state policies
LA River
Awareness of these challenges is growing, providing an opportunity for action
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Thank you!
These slides were created to accompany a presentation. They do not include full documentation of sources, data samples, methods, and interpretations. To avoid misinterpretations, please contact:
Caitrin Chappelle ([email protected]; 415-291-4435)
Thank you for your interest in this work.
Managing Wastewater in a Changing Climate
Caitrin Chappelle
Research supported by the California Association of Sanitation Agencies, the S. D. Bechtel, Jr. Foundation, and the US Environmental Protection Agency
April 22, 2019