Reading Reflection 2

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P1: OTA/XYZ P2: ABC c02 JWBT312-Novotny August 11, 2010 7:3 Printer Name: Sheridan

II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 97

of nature). Costs are for capital expenditures and for operation, maintenance, and replacement (OMR) of the facilities and best management practices. Both benefits and costs are affected by the cost of borrowing the funds to implement the facilities and the opportunity cost, which is the value of benefits that would have accrued from spending the money elsewhere, instead of using the borrowed funds on building and operating the facility.

However, current large utilities operating and managing water/stormwater/ wastewater facilities and other urban-water-related infrastructure are designed and operate under mandated environmental goals and standards that must be achieved. According to the National Pollutant Discharge Elimination System (NPDES) and TMDL regulation, and sometimes court injunctions, if the mandated limits are not met, stiff penalties and fines may be imposed whose costs may exceed the cost of meeting the mandate. Consequently, the economics of operating these facilities is reduced to finding the design that would meet the environmental limitations at the least cost. Typically, the financing of large utilities is accomplished by issuing a bond offered to investors who receive interest payments, and the cost of borrowing must also be considered.

When only capital operation and OMR costs are considered, to some degree, the larger the facility becomes, the lower cost is. This is called the economy of scale, which in the 1970s led to the abandonment of many smaller treatment plants, which were replaced with long large interceptors and one or very few large regional treatment plants. Also when increased pollution of municipal wells and local water sources caused their decommissioning, some municipalities were looking for distant large sources and regional water treatment facilities. The result was a regionaliza- tion of the urban water and wastewater systems resulting in large costs of water and wastewater transfers (including clean water inputs). For example, in 2002, the large regional wastewater treatment plant in Fusina near Venice, Italy, was oversized but was operating near capacity because it was receiving infiltrated clean water and hence treating 25% dry-weather sewage flows and 75% clean water inflows that in- filtrated or entered the sewer and interceptor system during rainfall and also due to a high groundwater. Because of the flat topography, the cost of pumping was very large.

In many older cities with legacy infrastructures, the switch to the new paradigm will be gradual. In this case marginal pricing will be employed because the replace- ment of the old infrastructure will start with the existing most costly component; for example, new nutrient, heat, and energy recovery facilities will replace old and very expensive to operate and maintain secondary (activated sludge) and tertiary treat- ments with high energy demand and chemical cost.

II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY

It is now generally agreed that present cities, their landscapes, and their wa- ter/stormwater/wastewater systems are not sustainable; many cities, especially in the developing world, cannot provide an adequate amount of water, and the water that

Novotny, V., Ahern, J., Brown, P., & Ahern, J. (2010). Water centric sustainable communities : Planning, retrofitting, and building the next urban environment. ProQuest Ebook Central <a onclick=window.open('http://ebookcentral.proquest.com','_blank') href='http://ebookcentral.proquest.com' target='_blank' style='cursor: pointer;'>http://ebookcentral.proquest.com</a> Created from asulib-ebooks on 2020-08-19 20:29:04.

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98 URBAN SUSTAINABILITY CONCEPTS

is provided for a few hours a day is contaminated by cross-connections with sewers due to low pressure and damaged pipelines and severe environmental pollution. In the poorest nations, even the basic necessities such as sanitation are not provided. Even in developed countries, infrastructure built decades or even centuries ago is crumbling and will require massive investments for repairs. Traditional subsurface stormwater drainage can only handle smaller storms, with the recurrence intervals ranging from less than two years (e.g., Tokyo) to five years (standards for storm sewer designs in many U.S. and European communities); CSO overflows are al- lowed even with abatement ten or more times per year, which again is unacceptable to the public because after each storm beaches and swimming areas are closed, or are unsuitable for swimming at all times. Hence, these systems are not resilient to extreme events. In Tokyo and Osaka, Japan, large portions of the metropolitan ar- eas are actually located in the floodplain, and city engineers cope with this fact by turning the yards of apartment buildings into flood storage basins, with a forebay and a warning system providing 15 minutes to the tenants to evacuate the yard when floods occur (personal observation by the primary author). The current unsustainable situation will be further exacerbated by:

� Population increases (urban population is expected to increase by 50% in the next 20–30 years; many new cities will be built in Asia and other parts of the world)

� Increasing living standards (more demand on food and, consequently, water resources)

� Global warming (increasing sea levels, changes in drought and water availabil- ity patterns) (ICPP, 2007)

� Emerging new pollutants (endocrine disruptors, pharmaceuticals residuals, more frequent massive cyanobacteria bloom outbreaks)

� Increasing water scarcity; currently about 0.7 billion people experience true water scarcity (they live on less than 25 liters per person per day), which is expected to grow to more than 3 billion people by 2025 if nothing is done (Zhang, 2007; Colwell, 2002)

� Conversion of urban waters into effluent dominated water, which will require management of the total urban water hydrological cycle and decentralization of the urban sewerage

� Increased flooding due to global warming effects, increased imperviousness, and other land use changes in the watershed

� Energy shortages because the world is running out of oil; production of biofuel from corn and other crops is driving food prices up

The new fifth paradigm of urban water/stormwater/used water management is a variant of the fifth paradigm of integrated water resources management (IWRM) de- scribed by Allan (2008) for water resources development. This paradigm is derived from the premise that water is an economic and social resource. Adoption or rejection

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II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 99

of IWRM is closely related to the political system in which water users and policy makers operate, and poverty is the main impediment to the adoption of econom- ically and environmentally sound water management (Allan, 2008). Treating water resources as an abundant social free good is a feature of the third paradigm, or current developed countries, and still is a paramount requirement of developing countries trying to catch up with the developed countries. However, today, it can be argued that even some developing countries, such as China and Singapore, have adopted IWRM concepts that have revolutionized their integrated urban water management and brought them to the forefront of world development, which may save these so- cieties from destruction by pollution and bring them great societal and economic benefits (China). Singapore today must be considered a highly developed country and leader in the area of integrated water management and sustainability.

II.3.1 Emerging Sustainable Urban Water/Stormwater/ Used Water Systems

The concepts of the new paradigm of sustainable water centric ecocities have been emerging for the last 15 years in environmental research and landscape design labo- ratories in Europe(Sweden, Germany, the United Kingdom), Asia (Singapore, China, Japan, and Korea), Australia, the U.S. (Chicago, Portland, Seattle, Philadelphia, San Francisco), and Canada (British Columbia, the Great Lakes region). This paradigm is based on the premise that urban waters are the lifeline of cities and the focus of the movement towards more sustainable cities (Novotny, 2008), and its evolu- tion ranges from the microscale “green” building, subdivision, or “ecoblock” to macroscale ecocities and ecologically reengineered urban watersheds, incorporat- ing transportation, and neighborhood urban living as well. The new paradigm must include consideration of energy and greenhouse gas emission reductions, and must treat stormwater and reclaimed used water as a resource to be reused, rather than wasted (with high disposal costs). Therefore, the Cities of the Future will combine concepts of “smart/green” development and natural landscape systems with control of diffuse pollution and stormwater flows from the landscape. They will reuse highly treated effluents and urban stormwater for various purposes, including landscape and agricultural irrigation; groundwater recharge to enhance groundwater resources and minimize subsidence of historic infrastructure; environmental flow enhancement of effluent dominated and flow-deprived streams; and, ultimately, for water supply. The organic content and energy in used water will be treated as a recoverable resource along with reclamation and reuse of urban stormwater (Rittmann, Love, and Siegrist, 2008). The most obvious differences between the current and future paradigms are summarized in Table 2.1.

Mihelcic et al. (2003) focused on developing sustainability science in the wa- ter/wastewater field and emphasized that just focusing on green engineering, even with pollution prevention and industrial ecology, may not be sufficient to achieve sustainability because the material flow from these systems may still overwhelm the limiting carrying capacity of the ecosystem or may lead to unbalanced situations such as urban sprawl. Mihelcic et al. outlined the evolution from the environmental

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100 URBAN SUSTAINABILITY CONCEPTS

Table 2.1 Comparison of traditional cities and Cities of the Future (fifth paradigm) concepts1

Traditional Cities of the Future

Drainage: Rapid conveyance of stormwater from premises by underground concrete pipes or culverts, curb and gutter street drainage

Storage oriented: Keep, store, reuse, and infiltrate rainwater on-site or locally, extensive use of rain gardens, drainage mostly on surface

Wastewater: Conveyance to distant downstream large treatment plants far from the points of reuse

Local reuse: Treat, reclaim, and keep a significant portion of wastewater locally for local reuse in large buildings, irrigation, and providing ecological low flow to streams

Urban habitat infrastructure: No reuse, energy inefficient, excessive use of water

Green buildings (LEED certified): Water-saving plumbing fixtures, energy efficient, larger buildings with green roofs

Water, stormwater/wastewater infrastructure: Hard structural, independently managed

Local cluster decentralized management: Soft approaches, best management practices as a part of landscape, mimic nature

Transportation, roads: Overloaded with vehicular traffic and polluting

Emphasis on less polluting fuel, urban renewal to bring living closer to cities, good public transportation, bike paths, best management practices to reduce water pollution by traffic

Energy for heating and cooling, carbon emissions: Energy (electricity, gas, oil) brought from large distances, no on-site energy recovery, high carbon emissions

Energy recovery and reduction of use: Part of the heat in wastewater will be recovered and used locally without carbon emissions, biogas production from organics in waste, fuel saving by people traveling shorter distances, use of geothermal, solar, and wind energy that reduces carbon emissions

Overuse of potable water: Drinking water is used for all uses (household, irrigation, street washing, fire protection), large losses in the distribution system

Use of treated drinking water from distant sources should be limited to potable uses only, reused water or water from local sources for other uses, reduced losses in distribution

Economies of scale in treatment cost and delivery are driving the systems—the bigger the better

Triple bottom line pricing and life cycle assessment of the total economic, social, and environmental impact

Community expectation of water quality distorted by hard infrastructure and past abuses such as buried urban streams, fenced-off streams converted to flood conveyance and/or effluent dominated

Daylighting and/or renaturalization of the water bodies with ecotones (parks) connecting them with the built areas enhances the value of the surrounding neighborhoods and brings enjoyment

Low watershed resilience to extreme events, underground stormwater conveyance can handle only smaller storms, infiltration is low or nil, fast conveyance results in large peak flows

Surface drainage with floodplain ecotones, in addition to storage and infiltration, dramatically increases the resilience of the watersheds to handle extreme flows and provide water during times of shortages

1Source: Adapted from Valerie Nelson, unpublished document.

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II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 101

1972 - Clean water act ammended 1977 and 1987 1974 - Safe drinking water act

- Reactive - Reliance on abatement - Driven by regulations - Disregards resource consumption - Limited accountability

- Reduce - Reclaim - Reuse - Recycle

- Proactive - Beyond compliance - Life cycle Analyses - LEED criteria - ISO 1400 - Full cost accounting - Benchmarking

- More than ecoefficiency - Triple Bottom Line Economic Environment Society - Close cooperation of governments, corporations and citizens - Multifaceted accountability for both Public and Private Sectors

1990 - Pollution prevention act

End-of Pipe Treatment

Pollution Prevention

Design for Environment

Sustainable Development

1987 - Brundtland’ Comission on Environmenet and Development 2002 - LEED criteria

2007 - IPCC report on global warming and climatic changes

Figure 2.9 Adaptive progression of water management and urban pollution control from the end-of-pipe control to sustainable systems. Adapted and modified from Mihelcic (2003).

issues typical of the fourth end-of-pipe treatment paradigm to sustainable devel- opment (Figure 2.9). It could be noted that even in the countries that are making the fastest progress toward sustainability of some of their urban areas (Singapore, Sweden, China), the state of sustainable development is still more in design studios than a full reality.

Mihelcic et al. linked progress to the legislative acts that stimulated the activities. This indirectly says that society, by means of a discourse among the major groups of stakeholders and legislators, should decide on the goals. In a parallel process, science must provide the knowledge and support for these societal decisions. The process towards sustainability in a democratic society is stepwise and adaptive. For example, the focus of water pollution abatement after the passage of the Clean Wa- ter Act in 1972 was almost exclusively on point sources of pollution—that is, on polluted discharges from sewer effluents of cities and industries. The CWA included requirements for point sources to apply for discharge permits under NPDES per- mitting regulations, which also contained penalties for noncompliance. However, in less than a decade or so after the passage of the CWA and fast implementation of point source control goals, it became evident that these actions will not be enough to attain the goals of the Act, and it was realized that other sources must be included, such as urban stormwater. In 1983, the U.S. Environmental Protection Agency (EPA) conducted a scientific study of the pollution of urban runoff, the Nationwide Urban Runoff Project (NURP) (U.S. EPA, 1983), that gave the impetus to Congress to ask

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102 URBAN SUSTAINABILITY CONCEPTS

the U.S. EPA to issue regulations for the control of the pollution from urban runoff. In 1990 the Pollution Prevention Act was passed by the U.S. Congress, providing impe- tus for conservation, reclamation, and reuse of reclaimed stormwater and wastewater. In 1987, the Brundtland Commission report was published, making sustainability a global goal, and in 2007 the International Panel on Climatic Change made the need to drastically reduce carbon footprint and GHG emissions another global goal. The drivers for change towards sustainability have been presented in Chapter I.

The fifth paradigm, discussed at the Wingspread Workshop (Novotny and Brown, 2007; Novotny, 2008), offers a promise of adequate amounts of clean water for all beneficial uses. The new paradigm of sustainable urban waters and watersheds is based on the premise that urban waters are the lifeline of cities and the focus of the movement towards more sustainable and “green” cities. Summarizing the discus- sions at the Wingspread Workshop and their literature, the concepts of the new sus- tainable urban water management system and the criteria on which its performance will be judged include:

� Replacing the linear flow-through systems by the integration of water conserva- tion, stormwater management, and wastewater disposal into one system man- aged on the principle of a closed-loop hydrologic balance concept (Figure 2.10) (Heaney, 2007)

Exported water

Evapotranspiration

PRECIPITATION

Water treatment

EVAPO- TRANSPIRATION

Irrigation Return Flow

Roof

Irrigation

Sanitary sewers

Flow deprived (effluent dependent) river Effluent dominated river

E X

T E

R N

A L

S Y

S T

E M

Base flow BLENDING AND STORAGE

SUBSOIL

Waste water treatment

Storm sewers and channels I-I

IN T

E R

N A

L S

Y S

T E

Pervious irrigated

Pervious unirrigated Impervious

Figure 2.10 Total urban hydrologic cycle concept (adapted from Mitchell et al., 1996, and Heaney, 2007). The traditional fourth paradigm linear flow-through system will be replaced or retrofitted by a closed-loop system promoting and enabling conservation, water and energy reclamation, and reuse.

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II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 103

� Considering designs that reduce risks of failure and of catastrophes due to the effects of extreme events and that are adaptable to future anticipated increases of temperature and associated weather and sea level changes (IPCC, 2007);

� Incorporating green buildings (LEED certified) that will reduce water use by water conservation, and reduce storm runoff with best management practices (BMPs), including green roofs, rain gardens, and infiltration

� Incorporating heat energy and cooling water recovery from sewage in cluster water reclamation and energy recovery facilities (Engle, 2007)

� Implementing new innovative and integrated infrastructure for reclamation and reuse of highly treated effluents and urban stormwater for various purposes, including landscape irrigation and aquifer replenishment (Hill, 2007; Ahern, 2007; Novotny, 2007; LEED criteria (U.S. GBC, 2005, 2007))

� Minimization or even elimination of long-distance subsurface transfers of stormwater, wastewater, and mixtures (Heaney, 2007; Anon, 2008)

� Energy recovery from used water (wastewater); environmental flow enhance- ment of effluent dominated and flow-deprived streams; and ultimately a source for safe water supply (Anon, 2008)

� Striving for net zero GHG footprint by incorporating renewable energy sources into the system of the water–energy nexus

� Implementing surface stormwater drainage and hydrologically and ecolog- ically functioning landscape, making the combined structural and natural drainage infrastructure and the landscape far more resilient to extreme mete- orological events than the current underground infrastructure; the landscape design will emphasize interconnected ecotones connected ecologically with a viable interconnected surface water systems; surface stormwater drainage is also less costly than subsurface systems and enhances the aesthetic and recre- ational amenities of the area (Hill, 2007; Ahern, 2007)

� Considering the pollution-loading capacity of the receiving waters as the limit for residual pollution loads (Rees, 1992; Novotny, 2007), as also defined in the TMDL guidelines and documents (U.S. EPA, 2007); striving for zero pollution load systems (Metcalf & Eddy, Inc. 2007)

� Adopting and developing new green urban designs through new or reengineered resilient drainage infrastructure and retrofitted old underground systems inter- linked with the daylighted or existing surface streams (Novotny, 2007)

� Reclaiming and restoring floodplains as ecotones buffering the diffuse (non- point) pollution loads from the surrounding human habitats, and incorporating best management practices that increase attenuation of pollution, such as ponds and wetlands (Novotny, 2007)

� Connecting green cities, transportation needs, and infrastructure with drainage and receiving waters that would be ecologically based, protec aquatic life, pro- vide recreation, and by doing so be acceptable to and desired by the public

� Decentralizing water conservation, stormwater management, and used water treatment to minimize or eliminate long-distance transfer, enable water recla- mation near the use, and recover energy (Heaney, 2007; Anon, 2008)

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104 URBAN SUSTAINABILITY CONCEPTS

� Developing surface and underground drainage infrastructure and landscape that will:

1. Store and convey water for reuse and provide ecological flow to urban flow- deprived rivers, and safe downstream uses

2. Treat and reclaim polluted flows

3. Integrate the urban hydrologic cycle with multiple urban uses and functions to make it more sustainable

II.3.2 Triple Bottom Line—Life Cycle Assessment (TBL—LCA)

Coined in 1994 by John Elkington, the expression “triple bottom line” (TBL) was in- troduced to expand the notion of sustainability from a largely environmental agenda to include social and economic dimensions. Elkington suggested that companies should be using three bottom lines: “One is the traditional measure of corporate profit—the ‘bottom line’ of the profit and loss account. The second is the bottom line of a company’s ‘people account’—a measure in some shape or form of how so- cially responsible an organization has been throughout its operations. The third is the bottom line of the company’s ‘planet’ account—a measure of how environmentally responsible it has been” (Economist.com, 2009). In the simplest terms, the triple bottom line agenda encourages corporations to focus not just on the economic value that they can enhance, but also on the environmental and social values that they can enhance—or degrade (Elkington, 1997, 2001).

Hence, sustainability should also be evaluated using the “triple bottom line” (TBL) criteria which include (1) Environmental/ecological protection and enhance- ment, (2) Social equity, and (3) Economics (Anon, 2008; Brown, 2007; Novotny, 2008). Figure 2.11 is an illustration of the TBL concept. Using the TBL approach over the life cycle of the systems (40 or more years), it should be logically expected that ecocities built according to the fifth paradigm will outperform the current urban developments. To evaluate resiliency to extreme events in a TBL-LCA, consider: (1) flood-causing precipitation, (2) water shortages, and (3) extreme pollution. All three are affected by global warming; therefore, the TBL-LCA must consider emissions of GHGs. Research should increase understanding of how the new integrated urban drainage, water management, transportation, and resource systems work during times of stress, between stresses, and after stresses, and of how they impact population and respond to population increases and other socioeconomic stresses. Urban drainage systems must be clearly reengineered to become more sustainable and resilient to increased stresses.

The TBL-LCA methodology has been used by industries, but its use in the eco- logical domain is still evolving. While the economic and to some degree environ- mental sides of the assessment can build on the traditional analyses, the societal and ecological components are being researched. For one thing, societies in developed countries have already decided through discourse in the political and societal arena (e.g., the Clean Water Act in the U.S. and the Water Framework Directive in E.U. countries) that the components of the TBL are not equal—that is, the integrity of the

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II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 105

Figure 2.11 Triple bottom line assessment concept. Adapted and modified from Elkington (1997).

water resources cannot be compromised to increase economic interests (antidegra- dation rule). All aspects of society are dependent on underlying ecosystem services. Nevertheless, to consider the tangible and intangible benefits and costs in the TBL we have to convert them into a common denominator, which is monetary (see Chap- ter X). Ecology and economics are thus inextricably linked. Very often it also means restoring the ecological function of the system that was damaged by the past third and fourth paradigm developments that focused only on economics. If either sys- tem is unhealthy, social systems fail. Both private and government sectors must be assessed and, obviously, must cooperate in a well-defined regulatory framework (Mihelcic et al., 2003). To some degree, in water resource development, the concept of the triple bottom line is not new, and the trinity of criteria have been incorpo- rated (in a slightly different form) in the water resources development guidelines (Maas et al., 1962). Hence, TBL concepts and criteria are built on the previous eco- nomic concepts by incorporating social and environmental costs into the total cost of

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106 URBAN SUSTAINABILITY CONCEPTS

producing goods, and accounting for all social and ecological tangible and intan- gible benefits of preserving and improving the environment/ecology and providing aesthetic and recreational amenities to the population in the intergenerational con- text, which is sustainability.

II.3.3 Water Reclamation and Reuse

Integrated resource management concepts view urban treated effluents as a resource, not as waste. As a matter of fact, the trend today has been to take “waste” from “wastewater” and replace it by “used,” creating a “used water” resource which can be reclaimed and used for various purposes: phosphorus needed for fertilizers can be recovered, and—because effluents, especially in sanitary separate sewers, maintain a relatively constant temperature—heat and cooling energy can also be extracted (Barnard, 2007). Effluent reuse for irrigation, even in an incompletely treated (or untreated) form, has been practiced in some countries for decades, sometimes for more than one hundred years. Examples include large-scale effluent irrigation in water-poor regions of China (e.g., the Beijing region), Mexico, India, the U.S. (e.g., Tucson), and Israel. Some irrigation systems in developing countries use untreated effluents, and the irrigation practice is a substitute for treatment. For example, 34 m3/s of untreated wastewater from Mexico City irrigates more than 100,000 ha of agricultural land up to 60 kilometers away from the city, with some serious ground- water and surface water contamination consequences and public health concerns be- cause farmers live near the irrigated fields and the watercourses bringing the raw sewage to them (Scott, Zarazua, and Levine, 2000). Treated effluent from Tucson, Arizona, irrigates golf courses and city parks. Use of a highly treated effluent for potable uses was attempted several decades ago in Namibia, in Africa, and is be- ing seriously considered in Los Angeles and other Southern Californian cities (see Chapter VI). An important part of water reclamation, reuse, and energy recovery is flow separation into:

� Black water containing fecal matter that contains most of the biodegradable organic matter that can be converted to biogas; pathogens; and also water from kitchen sinks with grinders (comminutors)

� Urine (yellow) water that contains most of the unoxidized nitrogen and about half of the phosphorus from human-used water (wastewater) in less than 1% of the total flow (without flushing)

� Gray water containing discharges from laundry, bath, and kitchen containing nonfecal organic solids from kitchen dishwasher, soap, and detergents, and some pathogens from showers and baths

� White water which consists of surface street and highway runoff contain- ing most of the toxic, sometimes carcinogenic, compounds such as metals, PAHs, petroleum hydrocarbons, oil and grease, salt, cyanides, and nonhuman pathogens

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II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 107

� Blue water which is clean water that may enter the drainage systems from clean infiltration-illicit inflows (I-I) and rainwater from illegally connected roof downspouts

Each stream contains different reusable resources such as that providing clean wa- ter for recycling (gray, white, and blue); fertilizer recovery (yellow and black); biogas and organic fertilizer/soil conditioner (black); irrigation (treated black, yellow, white, and blue); and raw water for water supply (white and blue). The highly concentrated supernatant from digestion of sludge, other organic solids, and leachate from landfills is a highly valuable resource from which fertilizer struvite (magnesium ammonium phosphate hexahydrate) can be extracted. The advent of smaller often packaged and automated treatment (water reclamation plants, or WRPs), providing high-quality effluent based on membrane bioreactors and filters (Chapter VII) enables the imple- mentation of a distributed and safe water-reclamation-near-the-points reuse, which can be a high-rise building, commercial area, subdivision, one or several city blocks, or a small suburban or even rural community. Reclaimed water for irrigation could retain most of its nutrient content, but the remaining pollutant should be at a level that would not impair the integrity of surface and groundwater resources, and be safe for human contact. In addition to irrigation, the reclaimed high-quality effluent can be used for:

� Toilet flushing in buildings � Street flushing and washing of infrastructure � Flow augmentation to provide ecological flow to streams that have lost their

base flow due to excessive upstream withdrawals and hydrologic modification of the watershed by urbanization

� Cooling � Groundwater recharge for indirect potable and nonpotable reuse

The present technologies that are being developed, tested, and put on the market also provide (Rittmann, Love and Siegrist, 2008) (see Chapters VII, VIII and X):

� Biogas produced by anaerobic decomposition of organic solid wastes � Hydrogen (H2) gas produced by fermentation of organic materials in special

microbial fuel cells or as an intermediate product of digestion in hydrogen fuel cells

� H2 gas can be used as fuel for a conventional chemical fuel cell, which produces combustionless, pollution-free electricity

� Direct electricity production in microbial fuel cells � Heat and cooling energy recovered by heat pumps from warmer effluents � Energy supplements by tapping into geothermal sources, and wind and solar

energy

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108 URBAN SUSTAINABILITY CONCEPTS

Compact treatments providing high BOD, suspended solids, nutrients, and pathogen removals are available, ranging from serving a few houses to populations of up to 20,000. These units provide effluents that could be as clean as the receiving waters into which they may be directed (Furumai, 2007; Barnard, 2007). Ultimately, potable water quality is achievable (Barnard, 2007); however, direct potable reuse is still not recommended (Chapter V). Today, distributed small-scale treatment plants can be installed in neighbourhoods, in the basements of shopping centers buildings (see Figure 10.3 in Chapter X) or large high-rise . Energy can be recovered from both wastewater solid residues (sludge) and organic solid wastes (Anon, 2008). Cur- rently, methane produced by landfills or anaerobic wastewater treatment plants is often flamed out without reuse.

Chapters V, VI, and VII present the most advanced and efficient water, fertilizer, and energy reclamation schemes.

II.3.4 Restoring Urban Streams

Urban streams and lakes in many cases spurred city development by providing hy- dropower for mills, navigation, water supply, flood conveyance, fishing, and recre- ation. Because of excessive pollution and demand for development land, at the end of the 19th century, pollution of urban streams became unbearable and urban surface water bodies began to disappear from the surface by being converted into under- ground storm and combined sewers or placed in culverts (Figure 1.13. Those water bodies that stayed on the surface lost the floodplain and riparian habitat through development. Because of the changed hydrology from imperviousness due to urban- ization, floods increased, and the capacity of the streams was no longer sufficient to handle them. Cities responded to this by lining the surface streams with concrete or masonry and converting them into lifeless flood conveyance channels, often fenced off to prevent public access (see Figures 1.16, 1.17, and 2.12 left).

Today, along with the cleanup of urban runoff and separation of combined sewers, stream restoration and daylighting (bringing a buried stream to the surface) projects

Figure 2.12 Lincoln Creek in Milwaukee, Wisconsin. Left, channelized before restoration; right, after restoration. Photos by V. Novotny.

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II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 109

are being carried out in many cities. It does not make sense to use sewers to carry cleaner treated runoff. Restoration of urban streams is only possible after the ma- jor point sources of pollution, including CSOs and SSOs, have been eliminated. It is a complex process that begins with the identification of the cause of impairment (impaired habitat, insufficient base flow, and erosive high flows), followed by imple- mentation of best management practices to control the stormwater flow and pollution inputs, removal of lining, restoration of natural sinuosity, pool and riffle sequence and habitat restoration, removal of stream fragmentation (bridges, culverts, channel drops, and small dams impassable to fish and other aquatic organisms), and riparian (flood) zone restoration (Novotny, 2003). Habitat degradation is the primary cause of the impairment of the integrity of urban streams (Manolakos et al., 2007; Novotny et al., 2008).

The major reasons for and benefits of restoration and daylighting are:

� Water, fertilizer, and energy reclamation from municipal used water (waste- water) appears to be inefficient if the reclamation unit is located many kilome- ters downstream, and the reclaimed water with or without fertilizers would have to pumped back to the city for reuse. It may be more efficient to install smaller compact reclamation units closer to the points of reuse of both reclaimed water and energy. It would also make a lot of sense to use some of the reclaimed flow to improve base flow conditions in the existing restored or daylighted streams.

� Bringing the streams to the surface provides larger capacity to handle flows (Chapter IX).

� Reclaimed and renaturalized floodplain with storage ponds, wetlands, and buffers provides treatment and attenuation of runoff from surrounding areas and storage of excess flows, and it has many other uses such as wildlife habitat, parks, and recreation (Chapters III and IV).

� The stream corridor is an ecotone that provides ecological and hydrological connectivity needed to sustain aquatic and terrestrial wildlife and provide pub- lic recreation and enjoyment.

� Restored streams are universally known to bring great economic and revitaliza- tion benefits (Lee, 2004).

Figure 2.12 shows the stream restoration in Milwaukee, Wisconsin. Restoration is still more or less an art, rather than a science. Restoration of streams damaged by urbanization—often to the point of conversion into underground sewers—should be a key component of green development. Today, raw sewage inputs into surface streams, or underground culverts carrying the buried streams have been or are be- ing eliminated, and the buried streams are becoming storm sewers (with insufficient capacity to handle flows from extreme storms, in most cases). The restored and day- lighted streams will become technically a part of the surface drainage system, but they should be ecologically viable and functioning, pleasing to the public, and able to provide recreation as well as enjoyment. Surface drainage is also more resilient to flooding, as documented in the case of the buried Stony Brook branch under the

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110 URBAN SUSTAINABILITY CONCEPTS

Two underground culverts

Approximate 100 year flood level Approximate 100 year flood level

Stone masonry culverts 2.5 x 3.2 meters

Base flow

One way traffic with daylighted creek

Figure 2.13 Proposal for daylighting of the historic Stony Book buried under the streets of Boston about one hundred years ago on the Northeastern University campus. The photo on the left shows the current situation; on the right is the daylighting proposal by the Capstone Design student project. The left culvert will carry sewage flows with a portion of stormwater runoff. The channel on the right will carry a portion of the “clean” Stony Brook.

campus of Northeastern University in Boston (Figure 2.13) (see also Chapter 1 for a brief history of Stony Brook). Today, most of the buried Stony Brook is not a combined sewer anymore; it carries relatively clean water from an upstream nature reserve and stormwater from the city. One of the key requirements of daylighting and urban stream restoration is to provide and recreate good base flow that can be from natural sources (springs, wetland), if available, or created or supplemented by highly treated effluent from nearby high-efficiency treatment plants or stormwater runoff stored in ponds, wetlands, and recharged shallow aquifers. Base flow of urban streams has been lost because of the high imperviousness of the surrounding water- shed and shallow groundwater infiltration into sanitary sewers, basement dewatering into sanitary sewers, and leaks into other underground infrastructure (underground garages, subway and freeway tunnels). More discussion on urban stream restoration and daylighting will be covered in Chapter IX.

II.3.5 Stormwater Pollution and Flood Abatement

Since the late 1970s scientists and urban planners have been developing and imple- menting best management practices (BMPs) for controlling pollution and peak flow of urban runoff. Prior to 1970, urban runoff was considered clean and a “diluter” of more concentrated, often untreated, point source pollution. Sewer separation or

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II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 111

building underground storage basins and tunnels were general solutions to the prob- lem. An extensive U.S. Environmental Protection Agency (1983) study, the National Urban Runoff Project (NURP), disputed this policy and found that urban runoff con- tains unacceptable concentrations of pollutants, including extreme concentrations of pollutants from de-icing chemicals in winter flows, such as salinity, sodium, chlo- rides, metals, and cyanides (Novotny et al., 1999), and, in the nonwinter runoff, sus- pended solids, oil and grease, COD, pathogens, toxic metals, and organics. BMPs to control diffuse pollution developed and implemented in the last 30 years can be categorized as (Novotny, 2003):

1. Source control measures (control of atmospheric deposition, reduction of ur- ban erosion, especially from construction; street sweeping; switching from ir- rigated lawns using large quantities of fertilizers to nonirrigated xeriscape)

2. Hydrologic modification focusing on infiltration (porous pavements, landscape infiltration, infiltration trenches)

3. Reduction of delivery (silt fences at construction sites, buffer strips, grass swales, in-line solids separation in sewers)

4. Storage and treatment (wetlands, ponds, underground storage basins with a follow-up treatment)

The BMPs listed above can be divided into structural (hard) and nonstructural (soft) (Chapter IV). Most structural BMPs implemented until the end of the last cen- tury were “engineered” and did not blend with the natural environment, nor did they try to mimic nature. Since one of the requirements of sustainable development is to restore and protect nature, most of the structural BMPs are not considered sustain- able, nor are they appealing.

Landscape architects (Ahern, 2007; Hill, 2007) have proposed that the BMPs listed above also be divided into:

� Those that remedy landscape disturbance and emission of pollutants � Those modifying the landscape and the hydrologic cycle to make them more

ecologically and hydrologically sustainable � Those that remove pollutants from the flow

Developers and landscape architects at the end of the last century realized that BMPs can be an architectural asset that can blend with nature and mimic natural sys- tems. Almost every structural engineered BMP has a natural-looking, hydrologically and ecologically functioning, and nature-mimicking equivalent (Figure 2.14).

With the exception of the source control measures mentioned above, in the past, BMPs were designed and implemented a posteriori—that is, after pollution had been generated from the land. BMPs provided treatment, and use as drainage was sec- ondary. The typical drainage design preference of the fourth paradigm was to di- vert urban runoff and snowmelt collected by street gutters and catch basins from impervious road and parking surfaces into underground conduits (storm sewers).

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112 URBAN SUSTAINABILITY CONCEPTS

Figure 2.14 Landscaped swale providing infiltration and pollutant removal (photo from Marriott, 2007).

Subsequently, the sewer outlets were connected to a pond or a wetland or—directly, without any treatment—to a receiving water body. Traditionally designed geomet- ric ponds were intended to attenuate the peak flows and provide some removal of pollutants, but their ecological worth was minimal.

At the end of the last millennium, the “green movement” began to change BMPs from relatively unappealing in appearance, with little or no ecologic value, to at- tractive and desirable assets of the urban landscape. Hence, mowed grass ditches, swales, and dry detention ponds were converted to rain gardens and bioretention facilities (Chapters III and IV). Now it is being realized that BMPs are not only ad- ditions to the drainage, but can be the drainage itself, in a modified more attractive form (Novotny, 2007). Best management practices can:

� Mimic nature � Provide and enhance surface drainage � Repair unsustainable hydrology by reducing flooding and providing enhanced

infiltration, and provide some ecological base flow to sustain aquatic life, as well

� Remove pollutants from the ecological flow � Provide water conservation and enable water reuse

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II.3 TOWARDS THE FIFTH PARADIGM OF SUSTAINABILITY 113

Figure 2.15 Engineering approaches to urban drainage from traditional to eco-engineering (adapted from Ahern, 2007).

� Buffer and filter pollutants and flow for restored/daylighted streams � Enhance recreation and the aesthetic quality of the urban area � Save money and energy (expensive underground conduits and pumping may not

be needed; swale-type rain gardens combined with green roofs and permeable pavements for parking lots and some streets may dramatically reduce the need for underground storm sewer capacity and reduce energy use)

Ahern (2007) and Lucey and Barraclough (2007) have pointed out the differ- ences between the traditional (civil) engineered and ecologically engineered compo- nents (Figure 2.15). Ecological engineering is becoming a new engineering discipline needed for the paradigm shift towards sustainable ecocities.

II.3.6 Urban Landscape

Landscape ecologists (e.g., Forman, 1995; Forman et al., 2003; Ahern, 2007; Hill, 2007) have proposed an ecologically balanced urban landscape with a river or a chain of urban lakes as a centerpiece. Based on these concepts, the urban landscape of the future will be made of interconnected ecotones preserving or imitating nature, threaded through the inhabited space with the river corridor. In addition to supporting biota and preserving nature and hydrology, the ecotones will also attenuate pollution

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