Paving, Paving Everywhere. Not a Drop Will Sink.
The Potential of Green Alleys
I recall standing in awe at the foot of Mount Whitney, the crown of the Sierra Nevada, watching clouds forming off the peaks of Whitney Portal. In the late afternoon sun, its sharp rock formations were analogous to a heat sink using evaporative cooling. Precipitation to the West eventually makes its way into the Pacific Ocean while, to the East, water culminates in the Great Basin. Imagine all the earth traversed, stones tumbled on riverbeds and the water’s slow weave through aquifers. And so, blinded by solar glare from snowy caps and desert browns, I followed the string of mountains, south, to Los Angeles.
Cities, marks of humanity stretching over the epidermis of a planet, are hard, impervious surfaces that disrupt the natural cycle. At the urban scale, in places like Los Angeles, we register notable changes in the microclimate as buildings and streets absorb sunlight throughout the day. They only begin to radiate stored heat into the night sky. Precipitation slips down buildings onto oily and grimy sidewalks and streets. Picking up speed, it seeps through grates, forced into complex stormwater drainage systems. It is then unloaded directly into major bodies of water. As a result, erosion and water contamination are prevalent. The groundwater table lowers and soil no longer slows down and filters out water contaminants.
Porous. Permeable. Pervious. Words that are finally percolating into urban centers as we explore solutions to problems like groundwater recharge and the urban heat-island effect (UHI). Groundwater recharge is the process of water migrating from the surface into the water table. UHI is an abnormal increase in air temperature compared to that of surrounding areas due to retention of heat by urban infrastructure such as buildings and roads.
Artificial drainage methods, once thought to be ideal, interrupt groundwater recharge that once contributed to a given microclimate’s evaporative cycle. The earliest of these—dating back to 3100 BC in the Indus Valley Civilization (now Pakistan and North India)—directed wastewater into drains beneath the civilization’s major streets. Ironically, this ancient system was more effective than many found in modern cities in the same region. Modern methods incorporate geotextiles and perforated plastic pipes into otherwise traditional pipe systems, improving the filtering of soil particles found in runoff.
Seattle's Street Edge Alternative project. Click to enlarge.
However, we can reduce or completely eliminate the demand on stormwater systems through use of permeable paving and water-detention methods such as bioswales. With these, we mimic and reestablish the natural process of filtration and end up with cleaner groundwater.
The first of its kind in major U.S. cities—begun in 1999—Seattle’s Street Edge Alternative project exemplifies these methods. By reducing street widths and offering non-curbed sidewalks on one edge, the project reduces impervious surfaces by 18 percent while directing runoff into bioswales and back into the ground. Studies conducted by the University of Washington have shown that the design successfully reduced 98 percent of stormwater runoff during the wet season.
Chicago Green Alley Program. Click to enlarge.
In 2006, Chicago’s Department of Transportation, with its 1,900 miles of impermeable alleyways, spearheaded an effort to reactivate this neglected urban fabric through the Chicago Green Alley Program. The program implements recycled permeable paving, re-graded properly into detention areas through use of bioswales. Appropriately enough, paving consists of recycled concrete aggregate, slag, and tire rubber. (View the Chicago Green Alley Handbook.)
Los Angeles started its own Green Alley Program on 900 miles of alleys in late 2008, inspired by the work of Jennifer Wolch, a professor of geography and director of the Center for Sustainable Cities at the University of Southern California. Similarly, Green Garage of Detroit, an organization led by Tom and Peggy Brennan, began work on a 220-foot section of an alley that will eventually flow into the two-mile Midtown Greenway Project.
Boston Architectural College’s (BAC) Green Alley Project puts Boston on the map alongside other major cities. Don Hunsicker, head of the BAC’s School of Design Studies and the Green Alley project manager, explains why the BAC is pursuing this project. "The BAC is committed not only to teaching sustainable design practices to our students, but also to making our campus more sustainable. The Green Alley Project is one example of that commitment."
The BAC’s Green Alley, a demonstration project of modest proportion sited on the college’s backyard, improves a section of Alley #444, between Boylston Street and Newbury Street. Interestingly, the project’s roots reside on the roof of the main campus building located on 320 Newbury Street. Initial studies of a green roof design for student use and education led Pat Loheed, head of Landscape Architecture, to suggest incorporating a green alley as a holistic top-down approach to stormwater management. The Green Alley Project took off from there with a grant from the Massachusetts Department of Environmental Protection for Phase I.
Phase I of the project is scheduled to break ground sometime in spring/summer 2011 on 1,600 square feet of alley space abutting the college’s Boylston Street building. Phase II will take on the complexity of 3,600 square feet of the alley’s thoroughfare, coordinating with neighboring businesses as well as meeting the requirements of city agencies and organizations such as the Architectural Access Board, Public Improvements Commission, the Back Bay Architectural Commission, and the Neighborhood Association of Back Bay.
Boston Architectural College's Green Alley Project. Image by Jovan Tanasijevic. Click to enlarge.
Improvements will be similar to those found in previous projects throughout the country—replacing the traditional use of asphalt and concrete with a four-foot deep layering of permeable surfaces. These will eventually mediate runoff from future green roofs, ultimately offsetting stormwater loads by replenishing the groundwater table directly. A monitoring well is also in place from which the Groundwater Trust can track changes as a result of these improvements. To showcase these methods and educate the community, informational components will be integrated into the project. The Green Alley and future green-roof projects reflect the BAC’s commitment to improving the future of Boston and its neighborhoods.
The benefits of using recycled permeable paving, with a high albedo (reflectivity), in conjunction with bioswales are numerous. Groundwater recharge is reestablished, cleaner water results, erosion and heat absorption are reduced, and construction and industrial waste find a new purpose. The long-term cost of installing and maintaining a permeable paving system is comparable to that of traditional stormwater drainage.
In concert, these methods have the potential to eliminate the load of stormwater on existing drainage systems while reducing UHI due to asphalt paving that interrupts the natural evapotranspiration cycle. If we reduce the heat stored by paving, we can carry the same effort onto vertical surfaces of buildings and their roofs. This ultimately lowers the peak demands for cooling buildings and reflects a more energy-conscious city plan.
The BAC’s Green Alley Project hopes to persuade us to take larger stock of our underutilized urban fabric, reimagining its purpose and value in the city’s fabric. If we apply this kind of thinking to areas such as alleys and large swaths of parking, we can create a more vibrant and useful resource for our community.
Put a LID on it
It’s time to think of stormwater as a natural resource. Low Impact Development (LID) offers an alternative to old drain-and-dispose techniques.
New Englanders do not generally think about water scarcity when they look around. Massachusetts receives about 45 inches of precipitation annually — an abundant water supply by national standards. In fact, people are likely to be concerned about too much water, especially when managing stormwater. Over the last century, as development grew more intensive, both in urban centers and suburban shopping areas, the major stormwater problem was how to get water off surfaces during major storms. It was, essentially, a waste-disposal problem. Accordingly, codes, technologies, and standards of practice all coalesced behind methods of moving stormwater offsite, quickly and in large quantities.
By the 1980s, people began connecting downstream flooding, erosion, and pollution problems with the high volumes of stormwater being flushed off developed landscapes. In response, new codes and regulations were established to reduce “peak flows” during storm events. Artificial ponds and other detention structures were built to temporarily store stormwater during heavy rains and release it at a pace that caused less flooding and erosion and filtered out some of the pollutants. These centralized structures relied on networks of drain pipes to collect the runoff from across the property.
Over the last decade, however, concern has been raised about stormwater’s role in a different problem: some of our rivers, streams, and wetlands are exhibiting new, dangerously low water levels between storms. In the Northeast, groundwater is the critical component of streams that enables them to be perennial (continuing to flow during dry weather). Groundwater is water contained in saturated layers of soil and bedrock below the land surface. Where these saturated layers intersect the surface of the land, water seeps out and either pools on the surface, forming wetlands, or runs downhill, forming streams. The frequent replenishment of groundwater by precipitation (“groundwater recharge”) enables a continual feed to streams (“baseflow”).
However, when forests and fields are replaced with roads, buildings, and parking lots, rain and snow have fewer places to soak into the ground. The proficient flushing of stormwater and meltwater off vast areas of pavement — a point of pride for engineers for decades — is now understood to contribute to a drop in groundwater levels. Hydrologists have long understood this connection, but as it has become clear to a wider audience, the importance of groundwater recharge has come to the fore of Massachusetts water policy. Suddenly, the paradigm of treating stormwater like waste is turned on its head. How do we treat stormwater coming off our built landscapes like the important resource it truly is?
Enter LID
Some answers come from looking back at how stormwater was managed before the emphasis on centralized collection. Picture a rural road — no curbs, no catch basins, no detention ponds. The road is simply crowned to shed water off to the sides, into the trees, shrubs, or grass. In retrospect, we call this, quaintly, “country drainage.” The two factors that make this design effective at groundwater recharge are decentralization and the use of planted areas as stormwater receptacles. Decentralizing the places where stormwater is directed makes maximum use of pervious area for recharge. Plants help keep soils loose, which aids infiltration. As it turns out, soils and plants are at least as good at filtering out pollutants as most structural devices designed for this purpose.
The problem, of course, is that this type of design becomes difficult to duplicate when development intensifies and the ratio of paved to unpaved surface increases significantly. But with some design and engineering ingenuity, these older practices form the underpinnings of a new approach to land development called “Low Impact Development” (LID): minimize the area of impervious surface (through cluster designs, narrower roads, shared parking areas, smaller setbacks); use permeable materials for paving (such as porous asphalt and grass pavers); and use open, decentralized planted drainage instead of curbs, catch basins, and detention ponds.
In greenfield development (conversion of forests or fields to developed use), the LID process begins by characterizing a site’s natural grading, laying out a design that uses existing low-lying planted areas for stormwater collection, and minimizing land disturbance overall. Avoiding soil compaction by heavy construction equipment is particularly important, to retain permeability of the soils. This approach contrasts with the conventional practice of beginning a project by clear-cutting and grading a site down to the known quantity of a flat, blank slate. It also means that LID projects are inherently harder to replicate in cookie-cutter fashion. This can add time and expense in the design phase, but often saves money in infrastructure and materials costs during construction. In redevelopment projects, the LID approach may have to rely more on imported soils, newly planted areas, and conversion of pavement to permeable alternatives in order to increase groundwater recharge.
In both greenfield and redevelopment contexts, studies comparing the cost of LID to conventional approaches attempt to balance the higher costs of design and specialized materials often associated with LID against the higher costs of stormwater infrastructure, land alteration, and overall area of impervious surface often associated with conventional development. A recent study from the US Environmental Protection Agency demonstrated that, project-for-project, the LID approach can usually hold its own from a profit perspective and is frequently a cost advantage for developers. As material availability, design know-how, and consumer awareness about the environmental advantages of LID expand, these cost advantages can be expected to grow.
However, LID developers currently face an additional set of hurdles that, in Massachusetts and elsewhere, can trump these advantages. They often have to factor in increased project costs associated with obtaining waivers from local boards and conducting sometimes extensive engineering studies to demonstrate to local boards and officials the advantages of the LID alternative over the “by-right” approach dictated by codes.
In recognition of the substantial obstacles posed by existing laws and regulations, Massachusetts state government has been working with stakeholders over the last several years to revise state stormwater regulations to promote LID, implement incentives, and fund demonstration projects. Government agencies have also been working with nonprofits and private-sector advocates to develop educational materials and provide technical assistance to local communities interested in becoming more LID-friendly.
Next Steps
Outreach efforts, especially those targeting municipal boards and decision-makers, will remain important, as Massachusetts land-use practices are still primarily determined at the local level. Simultaneously, general education is needed to help shift the public aesthetic away from some of the conventions that have come to characterize typical development, such as large lots and setbacks, wide roads, and extensive curbing.
A recent study demonstrated that the LID approach can usually hold its own from a cost perspective and is frequently a cost advantage for developers.
Perhaps just as important, however, is pursuing answers to some of the outstanding scientific questions about LID — especially those that might refine the message itself. How significant are impervious surfaces compared to other factors contributing to low flows in streams and rivers, such as over-pumping of groundwater wells and structural barriers such as dams? Are there places or conditions that are more and less appropriate for the LID approach? How will various LID techniques function in the extreme climate conditions of New England? And perhaps most importantly, how can we be sure that we are not inadvertently creating new problems as we are fixing the old, much as we discovered with the stormwater management philosophies that drove development through most of the 20th century?
New studies are starting to address some of these questions. For example, a recent state-funded analysis by the Horsley Witten Group (with Bridgewater State College) of the Taunton River watershed found that loss of groundwater recharge due to impervious surfaces accounts for a 4 percent drop in annual baseflow over the entire watershed, but caused up to a 25 percent drop in baseflow for some of the small tributaries surrounded by substantial development. A recent study by the US Geological Survey similarly identified scale as an important factor in the impact of impervious surfaces on streamflow. Using a model to simulate the impacts of extensive implementation of LID throughout the Ipswich River watershed, researchers found that even converting half of the impervious surface runoff from all developed areas of the watershed back into soil infiltration would not appreciably improve flows in the river and large tributaries. However, they found that LID could significantly improve flow in small streams in the immediate vicinity of development.
Meanwhile, new research from the University of New Hampshire Stormwater Center has reduced concerns about the effects of cold climate conditions by monitoring a variety of LID features, including porous asphalt, at a demonstration site in Durham, New Hampshire over several winters of freeze-thaw conditions, conventional road sanding/salting regimes, and normal wear-and-tear. Other studies are looking at pollutant removal rates, infiltration rates, groundwater quality impacts, and the effects of varying levels of maintenance.
Paradigm shifts are slow, but momentum is a big factor. As LID starts to enter the mainstream consciousness, the ideas will gain increasing traction and in turn be tested by time, research, and practice — a case study in science shaping politics and policy.
Footnotes
U.S. Environmental Protection Agency, 2007, Reducing Stormwater Costs through Low Impact Development (LID) Strategies and Practices, EPA 841-F-07-006. http://www.epa.gov/owow/nps/lid/costs07/
2 Horsley Witten Group, Inc. (forthcoming, 2010). Taunton River Watershed Management Plan – Phase II: Implementation and Demonstration. Under contract to Bridgewater State College, Bridgewater, MA with funding from the Commonwealth of Massachusetts. http://www.horsleywitten.com/tauntonwatershed.
3 Zimmerman, M. J., Barbaro, J. R., Sorenson, J. R., and Waldron, M. C., 2010, Effects of Selected Low Impact Development Techniques on Water Quality and Quantity in the Ipswich River Basin, Massachusetts: Field and Modeling Studies, U. S. Geological Survey Scientific Investigations Report, 2010-5007.
4 Roseen, R. M., et al., 2009, Seasonal Performance Variations for Storm-Water Management Systems in Cold Climate Conditions, Journal of Environmental Engineering. 135:3(128).
http://www.unh.edu/erg/cstev/pubs_specs_info.htm#pubs
Mapping the Floods
They’re from FEMA and they’re here to help. Really.
In 2003, the Federal Emergency Management Agency, perhaps best known for its response to the New Orleans floods of 2005, began remapping flood plains nationwide, digitizing and updating elevational data that had remained on government maps since the 1970s, and generating new data for densely populated and high-risk areas. This large-scale government effort has several aims: to determine what properties should carry flood insurance, to produce more-accurate assessment tools for flood hazard, to create maps that can be tied to GIS databases and used as planning tools, and, at its core, to guide future development away from high-risk or environmentally sensitive areas.
As the new maps have been released over the past year, they have had sometimes dire financial and design consequences for landowners, developers, and municipalities. Being in a flood zone increases construction and insurance costs substantially, and residents and business owners in a flood zone, whether it is classified as high risk or not, are required to buy flood insurance if they have a federally backed mortgage. Government officials take the maps into account when they establish zoning and building standards, plan infrastructure and transportation, and prepare for and respond to floods. In Massachusetts, about 50,000 properties carry flood insurance, a strong indicator of the number in flood zones.
At their best, the new digital maps factor in topography, hydrology, erosion, and changes in population density, but they ignore climate-change projections. Flood-prone areas are generally defined by one of two hazard levels: 1-percent-annual-chance flood (also known as the 100-year flood) areas and 0.2-percent-annual-chance flood (also known as the 500-year flood) areas. FEMA defines a flood as a condition where two or more acres of normally dry land or two or more properties are inundated by water or mudflow. The previous paper maps were often based on 1960s- and 1970s-era US Geological Survey 10- and 20-foot-interval contour maps, with additional surveying by engineers performed only in those areas historically known to be flood prone.
The maps do not become official until the public-appeal periods expire and FEMA releases them in their final form, but their impact already is being felt across the Commonwealth even in this preliminary phase. For any new construction or substantial improvement (work totaling more than 50 percent of the purchase value of the property), developers or owners are required to build to current flood-zone standards, which usually means raising the lowest level to above the flood level. In Hull, a builder renovating an old rooming house was told that, in order to go forward with the work, he would have to elevate the house by 3 feet and place it on piers. In Provincetown, an estimated 600 properties, including the Town Hall, are being reclassified. In the Alewife area of Cambridge, more than 100 properties have been newly determined to be in a flood plain. In Newburyport and Salisbury, hundreds of properties on both sides of the Merrimack River are affected, and town officials are challenging the FEMA flood map designation. The maps have gone into effect in Suffolk and Bristol counties, and about 80 homes in the Savin Hall neighborhood of Dorchester are now officially in a flood plain.
The impact of the new flood plain maps is already being felt across the Commonwealth.
Following the law of unintended consequences, even structures intended to prevent flooding can subject nearby property owners to FEMA scrutiny. Dams, levees, dikes, and hurricane barriers need to be certified as meeting federal standards. Without this certification, properties adjacent to these public works are officially considered flood prone. In Chicopee, a 7-mile-long riverfront levee system protects the town from floods, but it has to be repaired and recertified by FEMA, at a cost of roughly $6 million, or approximately 5,000 properties will be classified as being in a flood plain. New Bedford’s hurricane barrier, a 3.5-mile-long steel and stone structure from 1966, will have to be recertified as well, and city officials are struggling with how to pay for the necessary engineering studies and recertification of the hurricane barrier. (Similarly, in parts of New Orleans, map certification will be delayed until 2011 due to the ongoing levee reconstruction project.)
As FEMA’s Mike Goetz, chief of New England Risk Analysis Branch, explained, the National Flood Insurance Program (NFIP), of which FEMA flood maps are an integral and necessary part, “tries to make risk management and assessment a part of the everyday life and calculus of communities.” The program, established in 1968, encourages communities to exceed the minimum requirements for flood plain management — building at higher elevations and buying up properties in high-risk areas to create open space. Towns and cities can participate in the NFIP’s voluntary Community Rating System and earn points that reduce their flood insurance premiums. Goetz described its intentions: “We are trying to incentivize communities and show that doing these good things can actually not only improve the environment, but also that those who have to purchase flood insurance won’t be hit as hard financially.” Richard Zingarelli, the NFIP Coordinator of the Massachusetts Department of Conservation and Recreation, commented, “The flood insurance program does not want to burden homeowners, but we don’t want someone to take a summer cottage on a barrier island and turn it into a mansion.”
Thus far, FEMA mapping methods have not been without controversy. At this time, 92 percent of the US has been mapped by the agency, but only 21 percent of the country has maps that fully meet FEMA’s own data quality standards, according to a recent report from the National Research Council. The report, which the Research Council produced at the request of FEMA and the National Oceanic and Atmospheric Administration, argued that the agency could more accurately determine flood risk with newer mapping technologies such as LIDAR (Light Detection and Ranging), which measures elevation using aircraft-mounted lasers. Even more significantly, it noted that the maps must be continually updated to reflect natural and development-related changes.
The findings of the National Research Council point to a larger issue lurking in the muddy waters of the $1 billion FEMA project. Flood plains are dynamic entities, constantly shifting, with every new development producing runoff and erosion capable of impacting rivers and streams for many miles downstream. Just as the original FEMA flood maps of the 1970s were intended to be revised regularly but instead were left in place for 30 years due to the exorbitant cost of sustaining a massive, ongoing, nationwide mapping project, the new maps — already less accurate than they could be due to the reuse of outdated maps — will become increasingly inaccurate as time goes by. According to Zingarelli, “The intent is for the mapping to be a continual, ongoing process,” but this depends on funding from Congress. The maps’ inaccuracy over time will be accelerated by climate change, as sea-level rise (which some current predictions put at 6 feet by the end of this century) will affect not only shoreline sea levels, but also inland river and stream beds and hurricane frequency and severity.
To address these issues, FEMA has launched the next phase of its mapping project: Risk MAP (Mapping, Assessment, and Planning). It has begun to use LIDAR in coastal areas and along rivers and levees to produce more accurate maps, and now has fairly extensive data for parts of New England. As Goetz explained, “Risk MAP is being used to plan mitigation activities: it might mean purchasing flood prone areas (as a community or city or region), or elevating buildings. We’re not trying to add levees and dams. We’re trying to do fairly soft mitigation techniques with less impact on the environment.” In addition, FEMA is beginning to think about stormwater management as an issue that extends far beyond the flood zone itself, taking “a more comprehensive and holistic look at what’s happening in a watershed.”
The proactive, watershed planning approach FEMA is advocating suggests that, in order to keep up with the changing landscape, perhaps it is time to consider new, alternative modes of occupying the water’s edge that are capable of withstanding change and water infiltration. Architects, engineers, and landscape architects may be able to provide guidance and insight into the issue. American Institute of Architects’ Latrobe Prize winners Catherine Seavitt, Guy Nordenson, and Adam Yarinsky, the co-authors of the forthcoming book On the Water: Palisade Bay, have begun to investigate new ways of building on the waterfront. In their publication, they introduce the concept of “resilience,” a strategy focused on soft infrastructure such as constructed islands, reefs, piers, and wetlands that can absorb the impact of natural disasters. (Their work inspired the Rising Currents project and exhibition at the Museum of Modern Art.) As Seavitt explained, “Reframing the debate can create openings for action…. It is interesting to think that you can design something in such a way that it becomes beautiful, or a great amenity to a community, and somehow goes beyond the arguments or the entities that are there. More than just a strategy for mitigation or adaptation, it’s giving something back that’s even better.”
The High Tide of Opportunity
Working with water is a lot better than working against it.
In the space of four centuries, Boston has increased its land area by 39 times, from 1.2 square miles in 1630 to 48 square miles today. The entire area of the city is now 90 square miles, of which 54 percent is land and 46 percent water. Over the past century, the sea level has risen a little over 10 inches. By a conservative estimate, it will have risen a further 30 inches by 2100.
Why Does This Matter?
Boston, no less than Amsterdam, is a water city. In topography and climatology, as in history and culture, the past is prologue. If, as forecast, there is a significant rise in the level of the ocean, the expansionist narrative of the city’s development will be reversed so that by the year 2100, absent immediate and radical action, Bostonians will be revisiting the shoreline of the 1880s.
Boston, much like other coastal cities, has become increasingly aware of the challenges that sea-level rise poses for both existing and future development and the choices to be made — technical, economic, and social. In 2009, the San Francisco Bay Conservation and Development Commission held an international design competition for ideas responding to sea-level rise in San Francisco Bay and beyond. This year, the Museum of Modern Art and PS1 have joined forces to address the challenge of sea-level rise as it would affect New York City: project proposals by architects, artists, engineers, and others are the subject of a workshop and exhibition, Rising Currents. As stimulating as such events may be for ambitious designers, without political leadership, they are simply tinkering at the edge. To understand the gravity of the situation, imagine a replication of the inundation caused by Hurricane Katrina visited upon every coastal community in the United States. The tragedy of New Orleans in 2005 laid bare not only the vulnerability of the city’s physical infrastructure and its critical part in the economy of the nation, but also the social inequities sustained within that fragile crucible.
Facing the Facts
Published jointly by Allianz, a global financial services provider, and the World Wildlife Fund, Major Tipping Points in the Earth’s Climate System and Consequences for the Insurance Sector provides the most recent evaluation of the effects of climate change and the likely effects on the insurance industry. Combined sea-level rise is one of four critical areas addressed in the report, with a focus on exposed assets in port megacities and specifically those on the northeast coast of the United States.
Proposal for Boston Harbor Barrier, 1988. Antonio Di Mambro + Associates.
The financial stakes for Boston are not trivial. Assuming low and high projections of a 20-to-26-inch rise in sea level by 2050 (by the time today’s infant is in mid-career), the report projects an “exposed risk” to property damage and consequential loss ranging from $409 billion to more than $460 billion (think of 20 Big Digs or half the cost of the Iraq war).
In trying to imagine how such a flood might look and feel in Boston, there is some instruction in looking back to the flooding of Paris in 1910. Weeks of heavy rain and swollen watercourses upstream caused the Seine to overflow its banks and submerge the city, including the Île de la Cité and Notre Dame. This had happened 250 years earlier, in 1658, but the difference in modern Paris was that the flood water found new conduits in the sewers laid by Haussman and in the recently constructed Metro lines. So in addition to filling the cellars, the floods permeated the underground infrastructure of the city, water gushing in at every orifice, issuing forth into major railway stations such as the Gare D’Orsay and bringing the city to a halt.
Transpose this scenario to Boston. A relatively modest 12-inch rise in sea level is projected to happen, at the latest, by 2046 and, at worst, by 2016, a mere six years from now. Combined with a stiff northeaster of some days’ duration, the waves of the Atlantic are likely to top the threshold of subway stations such as Aquarium and South Station and to rush down the access ramps of the Central Artery and the Tip O’Neill tunnel to Logan Airport. In most readers’ lifetimes, and within the space of a few hours, high tides, aided and abetted by a full moon and high winds, could drown the modern city of Boston in the bathtub of the Atlantic. The floods of February 1978 (the “Great Blizzard”) and October 1991 (the “Perfect Storm”) not only presage the magnitude of what can be expected, but as “extreme events” they are also predicted to occur with increasing frequency.
What Are the Choices?
There are two choices before us as a city and as a country: to do nothing (or too little, too late); or to do what has to be done, and fast. Contrary to the conclusions of the Tipping Points report, damage to property would in some sense be the least of our problems, the greater being social abandonment, as we have seen in New Orleans.
Consider the do-nothing or “proceed cautiously” approach. Absent government intervention, decisions will be left to individuals and corporations. Some may choose to ignore the warnings, some may take adaptive measures, and others may choose to move inland out of trouble. And some, the poor, will have no choice at all except to bear witness to a generation of disinvestment followed by a catastrophic failure of the infrastructure. In other words, to do nothing is to make an undemocratic and unjust choice. Every man for himself and let the devil take the hindmost is not a strategy — it would be an abdication of leadership and social justice.
This leaves us with having to do something and, if the facts are faced, doing it fast.
What Are Others Doing?
While other cities and metropolitan areas have already taken action, it is worth noting that they have also taken time to accomplish their goals. The most common form of protection is the flood barrier. The floating barriers of Venice will protect the lagoon from storm surges of up to 10 feet. With completion scheduled for 2012, the project has been 25 years in the making. London’s Thames Barrier was a mere 10-year project, completed in 1984 — but in response to the devastating floods of 1953. The Delta Works in the Netherlands is a series of 250 miles of dams, dikes, locks, and barriers started in 1950, accelerated after the same North Sea flooding of 1953, and completed in 1997.
If Bostonians want to preserve their quality of life for the next generation, they had better act now.
The Dutch Delta Commission Report of 2008 is a deeply impressive document outlining the next phase of that country’s defenses through the year 2100. The commission spells out and embraces principles of humanism and sustainability as fundamental values driving its recommendations, committing an average of $2 billion per year through the end of this century.
What Can Boston Do?
Proposal for Boston Harbor Barrier, 1988. Antonio Di Mambro + Associates.
Climate scientists and actuaries have spelled out the probabilities and the consequences of sea-level rise for metropolitan Boston. Other port cities faced with similar challenges have shown us a range of strategies that are transferable to this city. We have learned from these examples that it takes a generation, say 35 years, to see a major civil project through from inception to completion. Within that span, by 2045, the water level of Boston Harbor will have risen somewhere between 12 and 36 inches. If, like the Dutch, Bostonians want to preserve and enhance the quality of life that they have enjoyed to bequeath to the next generation, then they had better act now.
Meeting this challenge requires forceful and visionary leadership at all levels of government to articulate a strategy that looks decades into the future. It is also clear that Boston cannot face this alone but must find common cause, nationally, with other coastal cities and towns.
We propose three parts to an effective strategy to “work together with water,” as the Dutch have put it:
Articulate the Vision. The crisis of sea-level rise obliges us to reexamine the value of the city as the crucible of our economy, our culture, and our community. While Boston may be a world center for medical research, the city is also a leader in social inequality. A vision for preemptive reconstruction is an oppor-tunity to right that wrong. In the words of Governor Winthrop, “the only way to avoid this shipwreck and provide for our posterity…we must be knit together in this work as one man.”
Establish the Scale. Antonio Di Mambro’s 1988 scheme for a protective harbor barrier running from Quincy to Winthrop is as important for establishing the scale and complexity of the response as it is for its physical vision. This multi-layered proposal combines a tidal-surge barrier, reconfigured harbor facility, transit line, highway, reclaimed land, and industrial, commercial, and residential redevelopment. It is an infrastructure that both protects the present and promotes the future.
Act Now. With a clear vision and a long-term goal, there are myriad actions that can be undertaken immediately: protect highway and subway entrances; raise the Harborwalk and create seawalls; establish an elevated datum for buildings; relocate electrical and mechanical equipment out of basements and above the flood levels; and develop storm-surge reservoirs with windmill pumping stations in the lowlands of the South Boston seaport.
The threat of sea-level rise is not immediate but it is urgent. The idea is not to respond to disaster but to preempt it. The challenge is not to succumb to fears (of inundation, decline, or increased taxes) but to see opportunities (of employment, urban revitalization, and social equity). Viewed with vision and discipline, sea-level rise presents the opportunity of a generation to refloat the city, its economy, and its people.
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