Concurrent Session G. Rain and Tides – How communities are addressing evaluation, engagement, planning, and mitigation in an age of unpredictable water
Afternoon Session
* 2 Training Contact Hours are available for this session.
* 2 AICP CM credits are available for this session.
Coastal Counties, Cities and Towns across the country are retaining planners and engineers to assess and mitigate flooding caused by aging infrastructure, intense and more frequent rainfall, storm surge, sea level rise and extreme tides. The causes and consequences of flooding on land, property, and human health, varies depending on geography, geology, infrastructure, and landuse activities. Stakeholders engage in collaborative processes to help define the problem and develop socially, economic, and environmental solutions. As a result, definition of the problem and solutions to flooding vary widely across the coastal landscape.
The City of Miami Beach, Florida is spending $400 million dollars to address flooding that occurs with regularity. Here in Maine, the City of Portland is embarking on an adaptation study in Bayside, and mid-coast island towns of Vinalhaven and Islesboro are engaging in vulnerability studies to evaluate critical locations and infrastructure.
This session explores the problems identified in several communities and the solutions these communities are seeking to understand and begin to mitigate flooding caused by aging infrastructure, intense and more frequent rainfall, storm surge, sea level rise and extreme tides.
Session Chair:
Lissa Robinson
Senior Civil Engineer, Hydrogeologist, Land Planner, GEI Consultants, Inc.
Speakers:
1:30pm – 1:55pm
Flood Vulnerability on Maine Islands: An Advanced Circulation (ADCIRC) Model of Penobscot Bay
Leila Pike, Nathan Dill
Ransom Consulting, Inc.; nathan.dill@ransomenv.com
Vulnerability to flooding due to storm surge and sea level rise is being studied on Islesboro and Vinalhaven using the latest NOAA and IPCC sea level rise projections and the advanced modeling storm surge data from the USACE’s North Atlantic Coast Comprehensive Study (NACCS). Planning around the ocean—tides, currents, water levels, and wave conditions—is inherent to the island community. Information on the vulnerability of coastal flood hazards that can be used for planning purposes is currently only available from regional numerical modeling studies that do not provide a sufficient level of detail to assess the flood hazard for individual communities, particularly in areas with highly complex coastal features like the Maine coast, or very specific locations, such as the ferry terminal of an island. The regional numerical modeling studies available for the Maine coast include recent flood hazard mapping undertaken by the Federal Emergency Management Agency (FEMA) and the USACE. When it is necessary to evaluate the hazard at specific locations, communities can benefit from additional local-scale analyses based on refined modeling driven by the regional model results. Along the Maine coast, the best available coastal flood hazard information comes from the USACE NACCS, which utilizes tightly coupled ADCIRC and STWAVE modeling to simulate tides, storm surge, and waves for extreme events including both tropical and extratropical cyclones. Here we present an example application utilizing the model output data from the NACCS to drive local-scale modeling and analysis of the storm surge and wave hazard in Penobscot Bay.
2:00pm-2:25pm
Designing Infrastructure in an Uncertain Future: Assessing Lifecycle Costs of Culvert Designs
Alex Gray
GEI Consultants, Inc.; agray@geiconsultants.com
The increasing frequency and intensity of storms is prompting many communities and state agencies to design and build infrastructure that is more resilient to our changing climate. This usually means making culverts wider and bridges higher so that larger riverine flows and higher coastal surges can pass safely under our roads. Construction costs for larger structures are generally more expensive than simply replacing in kind, and thus limit the number of capital improvement projects that can be undertaken in any given year under pre-established budgets. Is this trade-off (larger structures and fewer improvement projects) simply the price we pay for living in a changing climate?
This presentation will examine this question through a case study that sought to optimize culvert management by testing whether or not aging structures should always be replaced with larger alternatives. Replacement designs for six Maine DOT culverts were analyzed by incorporating long-term repair costs across a range of climate scenarios in addition to their initial construction costs. These total lifecycle costs were then compared across design options in order to identify the lowest cost design. When this process is replicated for an entire portfolio of culverts, decision-makers can replace more culverts over time – a necessity as our infrastructure ages.
Qualitative information about community and agency values and preferences can also emerge during this process – metrics that are often difficult to identify and define. Understanding the ways in qualitative and quantitative information interact will be important as we learn how to adapt to our changing climate.
2:30m – 3:00pm
Afternoon Break
3:00pm – 3:25pm
How Harpswell is Promoting Resilience to Changing Weather
Wendy Batson and Paul Ciesielski
Town of Harpswell Conservation Commission; rockgator@me.com
Harpswell is a coastal community, with many coves, and approximately 216 miles of shoreline. A large network of roads is needed to serve its residents, however, over 65% of the roads are private and not maintained by public funds. Some of these roads regularly top over on a King Tide.
To raise awareness of the need to begin planning, the Commission gleaned data from interactive maps and contacted all homeowners living on private roads affected by up to a two-foot rise in sea level and invited them to a set of workshops.
The first workshop addressed additional road maintenance that will result from higher tides. Discussion included the need to consider data projections in future maintenance projects and to develop an awareness of what future costs may be if their road would need extensive work to stay passable.
The second hinged on the first and spoke about the importance of a statutory road association as maintenance costs rise. If grant money were to become available to help offset costs – would they be eligible to receive?
Many road associations and individuals attended each workshop. Shortly thereafter, a few took advantage of the engineering services discussed at the first. One updated their by-laws in consideration of the topics discussed and another is upgrading to a statutory road association.
Since most of our roads are private, property owners may be bearing significant costs to keep their road passable. Statutory road associations will be an important tool as coastal resiliency grants become available.
3:30pm – 3:55pm
Bayside Adapts: Addressing Climate Change One Step at Time
Bill Needelman
Waterfront Coordinator, City of Portland, Maine; wbn@portlandmaine.gov
The Bayside Neighborhood of Portland is a growing urban redevelopment district that includes opportunities for diverse housing, employment, and entrepreneurialism. Located between the interstate highway and Portland’s Downtown, the area lies well positioned for sustainable growth with pedestrian friendly proximity to services, amenities, transit, and open space.
However, Bayside faces an uncertain future.
Challenged by low topography, aging public infrastructure, and a highly urbanized (impermeable) landscape, Bayside is vulnerable to flooding today. Ponding water impacts small areas of streets during today’s highest tides. Intense rain storms that coincide with higher than normal tides expand these low lying areas into wide spread flooding disrupting travel and business, and causing vehicle and property damage.
The City of Portland is facing these challenges with no specific policies or plans regarding sea level rise, future storm surge adaptation, or increased intense rainfall events. However, the needs of the neighborhood are being address in an ongoing iterative process: Bayside Adapts.
The process takes a phased approach to ask the questions: How does Bayside grow and succeed in a future with more water? What should the neighborhood look like in the future? What actions can property owners, residents, and City government take to create a neighborhood that intentionally addresses its relationship with more water?
The first phase, currently underway, recognizes that good data and stakeholder buy-in underlie all transformational change. The city has contracted with engineering consultants to identify key “data gaps” in the City’s infrastructure knowledge and understanding of potential climate change impacts. Simultaneously with the Data Gap Analysis, the City is partnering with the New England Environmental Finance Center to undertake a stakeholder and public outreach program to establish “goals for adaptation” to climate change impacts. Using funds provided by the National League of Cities, the City is additionally initiating a “design challenge” to energize activism, generate creative ideas, and to inform the goal setting process. The results of Bayside Adapts, Phase I, will lay a solid foundation for the city to later, in Phase II, establish sensible design parameters for future adaptation, to inform policies and regulatory amendments, and to undertake the difficult work of planning infrastructure and land use interventions that set the course for Bayside in the future. The presentation will provide a mid-process check in, describe the learning to date, and reflect on applications of the process to other neighborhoods in Portland and for other communities facing similar challenges.