Download Climate Adaptation Challenges for Boston`s Water and

National Association of Flood &
Stormwater Management Agencies
Climate Adaptation Challenges for
Boston’s Water and Sewer Systems
John P Sullivan P.E.
October 15,2014
Boston
1630
Boston
1630 -2012
Boston
2100?
Boston Water and Sewer Commission
• Provides water and sewer services to more than
one million residents, workers, students, shoppers,
conventioneers, hospital patients and visitors each
and every day.
• Owns and operates a system for the distribution of
potable water to approximately 88,000 active
accounts throughout the City of Boston.
• Owns and operates a system for the collection and
transport of wastewater and storm drainage in the
City of Boston.
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
BWSC Infrastructure:
Wastewater and Storm Drainage Systems
• 1,455 linear miles of sewers:
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622 miles of sanitary sewers
595 miles of storm drains
235 miles of combined sewers
3 miles of combined sewer overflow outfalls
8 pumping stations
35,934 catch basins
47,413 manholes
174 combined sewer regulators
430 CSO and stormwater outfalls
202 tide gates
8 rainfall gauges
Tide gates on CSO outfalls in Fort
Point Channel prevent high tides
from entering combined sewers
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Climate Change Risks
• Increased Rainfall
• Average annual rainfall will increase
• Storms will become more intense
• Storm drains and combined sewer systems will have to convey
more runoff
• Increased river flows and flooding
• Charles River, Neponset River and Mystic River may flood areas of
the City during storms
• Sea Level Rise and Storm Surge
• Storm surge with hurricanes and nor’easters will flood city streets
now.
• Sea level rise will increase the elevation of the storm surge and the
areas that will flood.
• Sewer systems may be inundated in flooded areas.
• Pump stations may be flooded and disabled.
• More streets may be flooded if the water has nowhere to go.
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Sewer and River Monitoring Systems
• Sewer Metering:
• Six permanent metering stations located near the
downstream end of BWSC’s sanitary sewer system prior to
discharge to the MWRA system.
• More than 20 other metering stations moving around the City
to identify problems and plan solutions.
• Characterize flow throughout the system and determine how
it reacts to climate change conditions.
• Identify and eliminate extraneous flow to increase capacity to
convey increased storm flows.
• River Data Analysis
• Rivers are regulated by dams and water levels by pumping.
• As annual rainfall and the intensity of storms increase, the
frequency of river flooding may increase as well.
• Account for more frequent and higher future river stages in
planning.
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Climate Change Scenarios for Planning
• Using information consistent with the IPCC and
National Climate Assessments
• Managing the uncertainty of the risks by
considering at the range of climate change
scenarios
• Looking ahead 25, 50 and 100 years in the future
Forecasted
Greenhouse
Gas
Emissions
Forecasted
Sea Level Rise
Source: Vermeer & Rahmstorf, 2009
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Analyzing Rainfall Data
Forecasted vs. Observed
Annual Rainfall
Storm Volume and Intensity
Forecasts
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Increased Monitoring
Changes in Rainfall
• Average annual rainfall is increasing, it is now about
52 inches per year – could be 65 inches by 2100.
• The Commission designs its storm sewers and
combined sewers based on a design storm.
• The design storm is statistically calculated based on
historical data.
• The current design storm is 4.8 inches in 24 hours, which
conveys 90% of daily storms in an average year.
• Climate change is increasing the size and intensity of this
statistical storm and it could be 6.65 inches by 2100.
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Evaluating Flooding Risks to Infrastructure
• Running 2-dimensional computer inundation models of
current and future storm surge conditions
• Identifying pump stations and other critical BWSC
infrastructure at risk of inundation
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Boston Harbor Sea Level Rise Trend
• Historical sea level rise is 0.1 inch/year
• Sea levels could rise from 3.8 to 7.2 feet by 2100.
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Risks Of Flooding With Sea Level Rise And Storm
Surge – Year 2060
Year 2060 Rain
Sea Level Rise, No Storm Surge
Year 2060 Rain
Sea Level Rise, With Storm Surge
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Risks Of Flooding With Sea Level Rise And Storm
Surge – Year 2100
Year 2100 Rain
Sea Level Rise, No Storm Surge
Year 2100 Rain
Sea Level Rise, with Storm Surge
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Boston Harbor Hotel
Boston Harbor Hotel
Boston Back Bay
Copyright © 2014 Boston Water and Sewer Commission 980 Harrison Ave. Boston, MA 02119 617-989-7000
Boston Back Bay
Mean High High Water +2.5 feet
Projected to occur by mid-century
Similar to flooding from Hurricane Sandy
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Mean High High Water +5’
Projected to occur by mid- to
late-century
Equivalent to flooding from
Hurricane Sandy if it hit during
high tide
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Mean High High Water + 7.5’
Could occur by late-century
Charles River Dam is over-topped
Sandy at mid-century
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Winter Storm Hercules, 2014
Christopher Columbus Park
Hurricane Sandy, 2012
Long Wharf & Morrisey Blvd
High Tide, 2011
Long Wharf
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Communication with the Public
The Beginning