A Pittsburgh-area model demonstrates it’s possible to solve problems of sewer overflows, stormwater runoff, and urban revitalization at the source–in the urban areas where the rain falls and the people live–by absorbing costs into incremental redevelopment.

By Bruce Ferguson, Richard Pinkham,
and Timothy Collins

This article presents a model for resolving a history of chronic sewer overflows into the public streets, parks, and waters of the Pittsburgh region, while simultaneously restoring and revitalizing the region’s urban communities and watersheds.

In the past, Pittsburgh’s rivers and streams failed to meet the "fishable and swimmable" objectives of the federal Clean Water Act. In the 1990s, pollution control agencies took legal action against 82 communities and the Allegheny County Sanitary Authority (ALCOSAN), which estimated the costs to fix sewer overflows and rehabilitate collector systems at nearly $3 billion.

Local proposals to fix the problems include big public works projects–storage tanks, detention basins, pipelines, and treatment plants. These facilities would treat the downstream symptoms by increasing capacity and throughput; upstream sources would still be generating the same amount of runoff and pollutants. The proposed projects would incur substantial long-term treatment and maintenance costs, and the public would pay off hundreds of millions of dollars in construction bonds. Large regional storage facilities, treatment plants, and high-capacity pipelines might also conflict with preestablished urban land uses. Such projects add nothing to the civic life of the community and typically provide no new habitat or other added value to the ecosystem.

Restorative Redevelopment

Map: STUDIO for Creative Inquiry

The Nine Mile Run model presents a "restorative redevelopment" approach to the sewers, ecosystem, and communities of the Pittsburgh region. Retrofit and redevelopment projects that are technically and economically feasible can improve the value and livability of the city while effectively restoring the watershed’s natural functions. The technical key to doing so involves removing stormwater from sewer systems and reintroducing it to the soil and vegetation. The humanistic and economic key is to integrate infrastructure improvements, community development desires, and ecosystem needs.

A panel of 60 local and national designers, engineers, landscape architects, artists, planners, and policy analysts developed the Nine Mile Run model, with participation from local citizens. Focusing on the 6.5-mi.² watershed of Nine Mile Run in central Allegheny County, participants sought to develop proposals capable of offering immediate benefit, but they also looked decades into the future, using all appropriate technically and financially feasible approaches to restore the watershed’s natural processes and revitalize its communities.

Sources and Solutions

The outfall of the main Nine Mile Run culvert at low flow (top) and after a rainstorm (bottom), when the runoff carries raw sewage and other urban pollutants with erosive power.

Sewer overflows and high stream flows begin with the excessive stormwater runoff in the watershed. Urban watersheds are characteristically heavily covered–40% or more–with impervious surfaces that deflect rainwater into surface channels and culverts, where it concentrates into erosive downstream floods. The runoff water carries with it oils from cars, parking lots, maintenance yards, and storage areas, and heavy metals from old construction materials. Stormwater is routed into sanitary sewers in many places, often producing overflows of raw sewage into streams.

If we think of our overflowing sewer system as a bucket spilling over, we have two options: (1) buy a larger bucket or (2) reduce the amount and slow the flow of water going into the bucket. Investing in increased sewer conveyance and treatment capacity without carefully examining the many ways of removing water from the system would be unwise. Reducing stormwater flows into the sewers can cost less, and it can produce additional benefits to the environment and the quality of life.

Because the soil in Pittsburgh’s watersheds is porous and permeable, it can infiltrate most of the water coming into contact with it, filtering out solid particles and incorporating them into the soil matrix. Microorganisms decompose pollutants and turn them into nutrients for the living system. Storage in the soil and the deeper groundwater turns intermittent pulses of rainfall into a perennial moisture supply discharging slowly, almost steadily, months after the rain falls, to the streams and wetlands where aquatic organisms survive over dry summers. Even after a soil has been churned and compacted by construction, nature tends to restore these kinds of processes wherever it is allowed to work freely. Recently environmental economists began referring to such natural conditions and processes as "natural capital" and "environmental services," assigning dollar values to them.

Taking advantage of natural processes to store and treat stormwater brings additional benefits. Recharging the groundwater supports riparian vegetation, providing wildlife habitat and opportunities for human interaction with the natural world. Reductions in impervious surfaces and increased tree plantings help moderate urban temperatures. Porous pavements can be designed to improve pedestrian access to desirable places. Revegetation of landscapes beautifies neighborhoods.

The informed, creative retrofit and redevelopment of urban places could solve many of Pittsburgh’s watershed problems at the source while revitalizing older communities. Many of greater Pittsburgh’s buildings, streets, land uses, and infrastructure have been in place for years. Their functions and performance proved adequate for the standards of their time. Today the region is reevaluating the obsolete technical systems it inherited and counting the mounting costs of potential reconstruction. This is a technical problem involving hydrology and engineering; it is also a social, economic, and aesthetic problem involving the communities of people and the way they live. While substantial conventional infrastructure improvements are clearly needed, restorative redevelopment provides an opportunity to reduce some of those costs, to produce multiple benefits from stormwater and sewer system investments, and to recruit new talents, energies, and budgets into the resolution of wet weather problems.

The interdisciplinary Nine Mile Run panel met in a "charrette"–a short, intense design and problem-solving event–and divided into teams to create four sample designs. We present two in this article: the designs for Hunter Park and Edgewood Crossroads. Each design integrates several stormwater management strategies into the built environment of its site. Each exemplifies restorative redevelopment by integrating the physical strategies into the social and economic life of the site and its neighborhood.

The designs were to be sympathetic with existing land uses and community values; consequently they involve few significant demolitions or replacements of structures. Instead, through combinations of incremental retrofitting and redevelopment, they selectively implement stormwater management techniques shaped by and embedded in the revitalization of the place.

Hydrologic Performance

The sample designs resolve existing site-specific issues, adapting techniques of construction and stormwater management to Pittsburgh’s fine-textured soil, frequent frosts, steep hillsides, and unstable geology. Each team had access to detailed soil and geologic data from published sources and participating scientists.

All the designs infiltrate or detain (in that order of preference) and treat the runoff from a two-year, 24-hour storm on-site, which in the Pittsburgh area has 2.5 in. of precipitation. Typically about 60 smaller storms take place between occurrences of a two-year storm. A facility with the capacity for the two-year storm also adequately manages the runoff from all the smaller, more frequent storms. This design threshold encompasses most of the rain that falls during a year, most of the erosive high flows, and essentially all of the "first-flush" pollution events. Managing this volume of runoff reduces the frequency and extent of sewer overflows, restores water quality, and replenishes groundwater aquifers. On the other hand, storms larger and less frequent than the two-year storm exceed the capacity of the onsite systems; to anticipate these occurrences, the designs provide overflow to streams or sewers. This approach is consistent with standards in the Monongahela River Watershed Stormwater Management Plan adopted by Allegheny County in 1993. Some of the sites also receive runoff from off-site; the plans manage this extra water in appropriate ways. Given the short design time of the charrette, the engineering of the recommended stormwater and sewer measures remains preliminary and would require careful validation and specification prior to implementation.

Budget

All designs meet the hydrologic performance criterion within a construction budget of $15/ft.³ ($2/gal.) of hydraulic capacity for onsite infiltration, detention, or treatment. This amount is within the range of costs for conventional detention tanks, basins, and bypass systems in the Pittsburgh region in recent years. The accomplishment of hydrologic objectives on-site yields a cost savings in downstream conveyance, storage, and treatment.

In addition to this stormwater management budget, each design utilizes an unspecified retrofit and redevelopment budget proportional to the nonstormwater benefit foreseen for each site-specific design. The nonstormwater budget would come from a housing, public works, or urban redevelopment agency or a homeowner or developer interested in supporting or investing in other aspects of each site-specific proposal.

For example, proposals for porous pavements can take advantage of pavement rehabilitation schedules necessary during the life of almost any street, sidewalk, or parking lot. When property owners or municipalities replace deteriorated impervious pavements, the owner bears the bulk of the cost for reasons other than stormwater management. The stormwater management budget funds the incremental cost of porous materials over those of nonporous materials that would not have a stormwater management benefit.

Multipurpose parks agencies, street departments, and homeowners associations maintain the dispersed, onsite, multifunctional facilities. These nonstormwater agencies are motivated to maintain their facilities as amenities for functional, aesthetic, and recreational reasons; the maintenance cost is covered by those budgets.

The short, intense charrette process did not allow time for detailed cost estimates that would have to take into account, among other things, the costs of design, land acquisition, legal work, maintenance, operations, and replacement. Instead, the charrette procedure placed trust in the experience and judgment of the team members to assess the rough magnitude of potential costs and to calibrate their designs to the given budget.

Hunter Park

Construction of Hunter Park's swales for stormwater infiltration, storage, and water-quality improvement

Hunter Park lies near the headwaters of the Nine Mile Run watershed. It is a neighborhood park in Wilkinsburg, at the northern terminus of Swissvale Avenue. This is a low income area, with neighborhood streets and sidewalks in poor condition. The park’s ball field, wading pool, basketball courts, and small playground are in disrepair, although all are heavily used in season.

The bulk of the park is in pervious turf, although it hides the culverted remains of a natural stream. In contrast, the surrounding residential blocks are mostly impervious with densely built houses, streets, and sidewalks. Most of the runoff from the impervious surfaces drains into sewers, contributing to downstream flood pulses, sewer overflows, water pollution, and reduced base flow. Diverting runoff out of Wilkinsburg’s sanitary and storm sewers and into its soil and groundwater would contribute to cleaner water downstream in the Nine Mile Run watershed.

Plan for Hunter Park rehabilitation

Despite the currently neglected condition of the Hunter Park area, it has a vigorous past that symbolizes the industrial development of the region. Before settlement of the area, the site was a V-shape headwater stream valley. In the 19th century a coal mine filled and flattened the site with yards and spoil piles; the stream was diverted around the periphery.

In the early part of the 20th century, the industrially created land forms served as a baseball field for the Negro League. Some of the best baseball players in the country played as semi-pros at Hunter Field. Beginning in the 1950s, a series of developments gradually transformed the site into a recreational park. The stream was culverted. By 1980 Hunter Park was one of four parks under the responsibility of Wilkinsburg’s Recreation Department. Today the local neighborhood depends on its park. The "dolphin" fountain is popular with neighborhood children. The bold landforms present unique open spaces and potential for multiple use. However, the park’s edges are ambiguous, parking is inadequate, and there are no formally defined entry points.

The site is in a valley with a drainage area of 59 ac., of which impervious roads and rooftops cover approximately 9 ac., or 16%. Additional impervious surfaces include driveways, sidewalks, parking lots, and park playing courts. Sediment clogs most drainage inlets; some drainage pipes are broken. Some grass swales in the park improve water quality to a degree but are undersized even for the small amount of water they carry. Concentrated runoff from nearby impervious surfaces has eroded some of the park’s drainage swales and steep sideslopes.

The underlying geology of the "Casselman Formation" forms the site’s steep valley slopes and the coal seams that fed the nineteenth century mine. This formation is a mixture of shale, sandstone, and other sedimentary rocks typical of large parts of the Pittsburgh region. Its considerable modification over the years by earthmoving and construction is typical of old urban and industrial areas.

The proposed design is a convergence of history, hydrology, recreation, and neighborhood revitalization. The design filters, detains, and infiltrates runoff to remove pollutants, reduce runoff contributions to sewers, and solve drainage and erosion problems. Because the site is at the headwaters of the Wilkinsburg and Nine Mile Run sewer systems, everything done on this site to reduce and treat runoff reduces overload and improves water quality in all the systems downstream.

The design uses complementary strategies for various portions of the catchment. At the upper end of the park, a woodland bioretention area consists of sand and soil mixtures planted with native plants. It includes a pretreatment area to dissipate the energy of inflowing runoff and to collect coarse sediment. A constructed wetland treats water at the upstream end of the ball field. It is planted with emergent and scrub-shrub plants in a complex microtopography. It filters pollutants, reduces peak flow rates, and stabilizes the flow of water into the grass swales below.

The Hunter Park site, catchment, and surrounding area

Swales take overflow drainage from the wetlands and runoff from the fields and surrounding slopes around the ball field and through the lower part of the park. The swales have grass and other vegetation, which help remove pollutants from runoff. For further infiltration and filtering, they are enhanced with beds made of sand and topsoil 1-2 ft. deep and 10-15 ft. wide.

At the bottom of the park, the area where coal mine shanty houses once stood transforms into a public square for the neighborhood. The once-culverted stream is reopened ("daylighted") through the square to convey stormwater in restored stream habitat as an amenity and focal point for the park. The stream is expected to carry 45 cfs during the two-year storm. The stream’s meanders are dimensioned for natural "dynamic equilibrium" with the flow. Bioengineering techniques will stabilize and protect the banks during two-year and 10-year storms. The daylit portion of the stream could continue into the residential block immediately south of the plaza.

Around the edges of the park, narrowing street pavements will reduce impervious cover and allow infiltration while adding more parking spaces on permeable edges. The pervious parking stalls are made of concrete pavers with grass, over a gravel bed. The open-celled paver surface and the deep gravel storage basin beneath it adapt the pavement construction to the region’s frequent frosts and fine-textured, slowly permeable soil. Although porous pavement removes and treats some water from the site’s drainage, the amount was not counted in the total capacity of the site’s restoration features or in establishing the capacity of downstream swales; it is an "extra" benefit.

In the residential areas all around and above the park, roof leaders, street gutters, and drainage inlets end up disconnected from the storm sewer system. This diverts their drainage into swales and across vegetated slopes in and around the park. Excess runoff remaining in the streets is conveyed to the park’s wetlands and swales for treatment.

Stone "traces" through the park mark lines of old mining features. Adding street trees results in air- and water-quality improvement. The combination of strategies preserves and celebrates the natural and cultural history of the area. The improved access to the park promotes its use. There are opportunities to learn about the hydrologic strategies through interpretative signs and guided tours.

Edgewood Crossroads

The design for Edgewood Crossroads illustrates restorative redevelopment at the other end of the income scale from Hunter Park. It also illustrates the aggregate economic benefits possible by repeating on-lot measures in many small, individual retrofit projects.

The train station as seen from the intersection of Maple and Edgewood Avenues. This intersection floods during large storms.

Edgewood Crossroads sits near the center of the Nine Mile Run watershed. It is the public center of the Borough of Edgewood, where a historic train station fronts on busy Swissvale Avenue. Across the street are old storefront commercial buildings, a church, and a school. Nearby are Edgewood’s town hall, public library, community swimming pool, and numerous well-kept old residences. Residential streets converge from several directions. Many pedestrians move through the area. Edgewood has dozens of civic groups and the social closeness almost of a village, and the residents consider the cluster of streets, structures, and open spaces around the old train station the unified center of their community. Protecting and enhancing the sense of community is the central task of any urban design here.

The underlying geology at the crossroads is based on an ancient river bed that left behind a relatively level "terrace" of gravel, sand, and clay over large areas in the central part of the Pittsburgh region. In the catchment uphill from the crossroads, the land is characterized by steep slopes; a geology of shale, siltstone, sandstone, and other sedimentary rocks; and fine-textured soil that typify the rest of the Pittsburgh region. The modification of the soil over the years by construction is typical of old urban places.

The impervious streets, roofs, and sidewalks of the site and its catchment generate runoff that ponds up in the street intersection, disrupting pedestrian and vehicular traffic. Eventually it flushes into storm sewers, carrying oils and other pollutants, while denying recharge of groundwater. As in many parts of the Pittsburgh region, some roof leaders here connect to sanitary sewers, contributing to sewer overflows downstream.

The Edgewood Crossroads site, catchment, and surrounding area. Click here for an enlarged view

The design for this site integrates the following community issues: reinforcing the social and physical sense of community, preserving public open spaces, reinforcing pedestrian access, eliminating street flooding, and bringing Edgewood into compliance with federal water-quality standards by separating storm drainage from the sanitary sewer system.

In the small community park facing the train station, a developed plaza becomes the gateway to the public greenway being developed in the new transit corridor. Here a prominent stormwater restoration facility integrates stormwater solutions and public education with urban design. The center is a depressed bowl, with a porous block bottom that retains and infiltrates stormwater. During rainfall, about 30 days per year, the depression diverts floodwaters off the street and the surrounding plaza; it fills and then slowly drains over a one- or two-day period through an infiltration bed beneath the plaza. On dry days, the plaza and the bowl serve for communal gathering and play; the wall around the bowl functions for sitting. Permeable unit pavers continue from the plaza across the street intersection to strengthen pedestrian connections. In the rest of the park, reforested steep slopes increase infiltration. Tree canopies absorb some rainfall before it reaches the ground and reduce air pollution and the cooling energy requirements of nearby buildings.

For the railroad right of way, a public agency currently proposes to pave a 40-ft. width for express bus service to downtown Pittsburgh. An alternative greenway option would emphasize nonvehicular transportation, which would eliminate vehicular emissions and minimize the demand for paved streets and parking areas throughout the greenway region. The greenway right of way would hold a 5-ft.-wide pedestrian path, a 10-ft.-wide cycle path, and two rows of trees and plantings. This would maximize infiltration for the full length of the right of way. Another alternative would emphasize light rail. Light rail tracks would allow infiltration across the entire right of way width; the permeable surface could be planted with grass to reduce ambient temperature. The light rail vehicles’ ability to accept riders from both sides would allow a central island for embarkation, which would leave enough space for a pedestrian greenway within the remaining right of way space.

The street intersection receives stormwater runoff from a catchment around and uphill from the crossroads. While some of the local storm sewers currently divert stormwater out of the catchment, the proposed design manages all stormwater within the catchment. Open lawns and playing fields in the catchment’s small parks and institutional grounds can serve the dual purposes of recreation and runoff control. Groundwater recharge beds could be constructed under these areas while maintaining their surface uses for sports and parks. For example, retrofit of a playing field to maximize infiltration would include aggregate beneath the turf. If a bed of gravel 18 in. deep with 40% storage volume were supplied over the entire 6.2 ac. of reasonably available area, it could infiltrate the entire volume of a two-year storm collected from an area of 18 ac. An alternative construction of preformed "infiltrator" chambers could provide the same capacity.

An additional strategy diverts the runoff of residential roofs into on-lot infiltration basins to significantly reduce stormwater inflows to the sewers. Infiltration and recharge features can be shaped to each individual lot. For example, a large residence has half of its 2,500-ft.² roof area draining to the front and rear yards, respectively. For each half of the roof, a bed of aggregate or infiltrator chambers with a storage capacity of 208 ft.³ (1,560 gal.) would infiltrate all the runoff from all rain events up to and including the two-year storm. The bed or trench must be properly spaced away from the house to avoid leaking of water into the basement.

During an average year, residential roofs yield runoff from more than 40 in. of precipitation. If 50% of the residential roofs in the catchment–an estimated 2.5 ac. of rooftop surface–are currently connected to sanitary sewers (the precise proportion of roof leaders connected to sanitary lines is unknown), then the proposed residential recharge beds would remove from sanitary sewer lines 372,000 ft.³ (2.78 million gal.) of stormwater per year. This could yield the sewage treatment plant an annual cost savings of about $5,500, based on treatment costs of $2 per 1,000 gal. This long-term annual savings would justify subsidizing the installation of private recharge beds. A one-time 3-R (Rooftop, Retention, and Recharge) grant of $1,000 per home would cover most or all of the installation cost. The cash value of the investment would be paid off in eight years and would continue to be paid again every eight years thereafter. Moreover, a program to disconnect roof leaders from sanitary sewers and properly manage these flows will address a recent Pennsylvania Department of Environmental Protection order, under the Pennsylvania Clean Streams law, for reduction of stormwater inflows to sanitary sewers. Where the savings accrue depends on institutional structures and sewerage systems. Currently, area municipalities do not pay wet-weather surcharges to ALCOSAN, and much of the wet-weather flow does not reach the treatment plant because of combined and sanitary sewer overflows.

Porous pavements at the parking lots of churches and other public places infiltrate additional stormwater. Alternatives in porous pavement construction suitable for local soils, frosts, and traffic loads include masonry pavers with open joints, a bituminous mix with open-graded aggregate, or gravel with a layer 4 in. deep of No. 89 fines over a layer 24 in. deep of uniform-graded aggregate 2 in. in diameter.

Throughout the catchment, drainage inlets can be modified to permit infiltration by adding a gravel bed or a perforated PVC pipe that extends away from the basin to infiltrate water into the surrounding soil. An open grate design and a slight berm in the pavement help the inlet capture a large proportion of the surface runoff.

Finally, increasing the urban forest reduces runoff, moderates urban climate, improves air quality, and reduces noise. A dense vegetative structure, such as that of trees, shrubs, and native ground covers, absorbs more rainwater than a turf slope and is more resistant to erosion during intense storms.

Plan for Edgewood Crossroads' Restoration and Redevelopment

Patterns of Restorative Redevelopment

We can make some general observations about the physical techniques and design processes that can produce integrated, restorative, sustainable approaches to infrastructure, ecosystem, and community objectives.

Make Components Multifunctional. Everything undertaken in a retrofit or redevelopment project should produce multiple, mutually reinforcing benefits. For instance, stormwater has traditionally been moved off city roofs and streets through a single-purpose system of underground pipes. Instead we can keep it on the surface, re-creating a lost creek, or infiltrate it into the soil to recharge the groundwater and nourish vegetation–in either case providing ecosystem benefits in terms of habitat for wildlife, human benefits in experiencing the beauty and wonder of natural systems, and financial benefits in reduced municipal costs of maintaining hidden infrastructure.

Whenever an important component of a project appears to be an undesirable "cost," seek ways to shape it so that it acquires additional desirable benefits. This enlarges the project and maintenance budget as the cost becomes absorbed into the provision of other necessary functions. Multiple functions as various as water-quality improvement, employment, housing, separation of storm drainage from sanitary sewers, parking improvements, noise reduction, pedestrian safety, temperature moderation, and social equity can and should be found in the design of every building, street, sidewalk, park, water course, drainage system, residential yard, and institutional landscape.

One crucial function of every restorative redevelopment is the education of people about natural processes and onsite connections to the watershed. Stormwater systems should be a visible and tangible part of the urban framework of the watershed.

During large storms, the demonstration infiltration basin in Edgewood Crossroads' public plaza captures runoff, which percolates into the subsoil within one or two days.

Use Every Square Inch. Cities are crowded places. The solution to a watershedwide problem has to be on-site, on every site, because there is nowhere else to go. Successful restoration and revitalization depends on utilizing every square inch of a retrofit or redevelopment project for positive, multiple functions. Every component is in the midst of community life and must have positive community benefit in addition to technical function.

As our older cities grew, the cumulative impacts of transforming the landscape mounted, and municipalities had to replace natural systems with cost-intensive infrastructure. Now, when much of the older infrastructure fails to perform to today’s or even yesterday’s standards, we have an opportunity to reconsider the form and function of the urban landscape-and ultimately integrate each site into a seamlessly operating whole.

The retrofit or redevelopment of every site can contribute incrementally to the restoration of watershed process. For example, retrofitting a single house with separation of roof drainage from sanitary sewers contributes only a small amount to the reduction of sewer overflows somewhere downstream, but the impact is both immediate and maintainable over generations. The solution to a watershedwide problem requires the contribution of many similar projects throughout the watershed. The cumulative public benefits are enormous. There must be a constant search for restoration and revitalization opportunities on additional sites. Once started, the endeavor must be maintained with purpose over many human generations.

Use Freely Available Natural Processes. Freely available natural processes can work for the great benefit of watershed restoration. Vegetated soil absorbs rainwater, and the chemical and microbial processes of the soil capture and degrade many pollutants that might be present. The infiltrated water recharges groundwater tables and restores flows to streams. These processes reduce peak flows and erosion, eliminate sewer overflows, prevent and mitigate pollution, and sustain watershed ecosystems.

The regenerative capacity of soils and ecosystems is strong everywhere in the Pittsburgh region. Natural processes are waiting to perform essential services. Taking advantage of them enacts a new concept of stormwater infrastructure. The idea of "green infrastructure" broadens the conception of stormwater infrastructure to include the capacities of soil and vegetation to absorb water and filter pollutants. This is a smarter, cheaper approach to infrastructure because it puts nature to work and reduces the work humans must do, in contrast to the more active systems of pipes and facilities for conveyance and mechanically dependent treatment.

Use Disconnections and Reconnections. Sewer overflows are usually the biggest pollutant sources in the watersheds where they exist, such as Nine Mile Run. The more one diverts stormwater out of sewers, the more downstream overflows and sewage pollution are eliminated. Separating stormwater drainage from sanity sewage conveyance is a basic and essential task for restoring old urban watersheds.

In particular, the drainage from impervious surfaces should be disconnected from sewers at every opportunity, no matter how small. In urban areas the drainage from impervious surfaces is the great bulk of runoff, and it carries significant amounts of urban pollutants. To disconnect rooftop drainage, each downspout can be detached from sewers and routed to dry wells, water gardens, and cisterns. To disconnect pavement runoff, the drainage from driveways and walkways can be pitched away from street gutters and onto vegetated soil; large parking areas can be broken up with "infiltration islands" or served by underground storage or recharge beds; and street drainage inlets can be detached from combined sewers and their stormwater diverted into vegetated swales.

Drainage "disconnected" from sewers in these ways is "reconnected" with its natural path in contact with soil and vegetation. The reconnection with natural processes reduces the volume of surface runoff, filters the pollutants, replenishes the groundwater, and maintains stream base flows. The volume of stormwater, which once seemed a hazard and a nuisance, turns into a resource and a productive public benefit.

Cooperate Among Disciplines. In conceiving and implementing retrofit and redevelopment projects, members of different professions–engineering, landscape architecture, the arts, policy, hydrology, economic development, and more–have insight into different problems and opportunities of watersheds and communities and different types of skills for analyzing and developing them. All of them need to be members of the project team. The choice of individual participants can be important to a project’s success. Individuals must be open to the unanticipated insights of members of other disciplines and willing to work with them in design.

Find Out What Is Possible. Diverse, flexible, economical techniques for treating and storing stormwater within urban retrofit and redevelopment projects have been proven in applications throughout the United States. Developers, public officials, and citizens in each locality need to be aware of the available alternatives.

The Nine Mile Run charrette brought together experts in restorative design and policy from various parts of the country with Pittsburgh natives profoundly experienced in unique local conditions. The results demonstrate that numerous techniques, old and new, can be applied in the Pittsburgh region, and specifically in the old urban neighborhoods, in ways that are economical, effective, and supportive of economic vitality and quality of life. Infiltration or detention of the two-year storm is possible within budgets no bigger than the already-accepted cost of "doing business" in the region, when the design process is informed of the full range of what is possible. These techniques also contribute to progress on other local agendas, including ecosystem restoration and community social and economic development.

Engage the Community. Most leaders and professionals recognize that decisions having profound impacts on people and places–infrastructure choices, facility sitings, provision of public amenities, policy development, and more–should be made with the full substantive participation of those who will bear the fruits (or potentially the costs) of those decisions. Moreover, each city (and its respective communities) has a unique social and political history, style of governance, method of public discourse, and capacity for action. We must carefully define local application of potential solutions and seek locally integrated forms of innovation. In that process we build cohesive cultural forces invested in long-term success.

How to Make These Things Happen

The patterns of restorative redevelopment exemplified in the Nine Mile Run model will solve watershedwide problems only if they are followed in many places across the watershed for many years into the future.

In Pittsburgh, as in many other cities, policies and institutions that monitor and guide infrastructure, environmental quality, and community vitality have developed over time in a piecemeal manner in response to specific local needs and momentary crises. Their accumulation over the years left a mishmash of laws, codes, regulations, departments, and districts that do not work well together. Many agencies are reactive rather than proactive in approach, and their actions often ignore important problems and solutions that are outside the scope of their responsibilities.

Today the Pittsburgh region faces a sewer overflow "crisis" caused by historical ways of doing business. We now know how to do better. The fixing of problems that once seemed narrow, technical, and frustratingly costly can in fact be a low-cost investment in long-term, multiple, mutually reinforcing benefits.

The vision of the Nine Mile Run model calls for resolving today’s problems in ways that make the city and its watershed live again. The ultimate goal is to restore human conditions and the natural ecosystem in the Nine Mile Run watershed to health and vitality. Meeting this vision requires both ambitious long-term objectives and realistic, affordable short-term initiatives. It also requires an integrated program of information generation, discussion, and planning on the part of citizens, elected representatives, and public agency staff. Policies intended to follow this type of model must be comprehensive and mutually reinforcing.

The charrette developed detailed action plans for each of the following policy objectives to support restorative redevelopment:

Establish a permanent coordinating body with the authority and financial security to plan, maintain, and manage the watershed’s interrelated infrastructure, natural processes, and urban land uses. The organization must transcend municipal boundaries. It unites the responsibilities of infrastructure management and ecosystem protection.

Manage the watershed’s sewer and stormwater infrastructure for efficiency, reduced costs, and reinforcement of natural processes and community vitality. For instance, using the capacities of soil and vegetation to absorb water and filter pollutants, as restorative redevelopment does, would focus limited community resources on effective systems that produce multiple benefits.

Restore the watershed’s hydrologic and ecological processes in a manner that utilizes and supports infrastructure rehabilitation and community redevelopment. This includes rehabilitating urban runoff by reconnecting storm drainage with the natural capacities of the watershed. It also includes restoring natural stream, wetland, and forest habitats in critical areas.

Enable, support, and require economic revitalization that reinforces infrastructure management and watershed restoration. Communities, agencies, and developers can structure redevelopment programs and projects in ways that support sewer rehabilitation and restoration of beneficial natural processes.

Status and Conclusions

The restorative redevelopment concept is slowly taking root in greater Pittsburgh. Wilkinsburg officially designated Hunter Park and its surrounding neighborhood as a redevelopment zone and now seeks funding for projects there. Edgewood Crossroads continues to be bound up in debates over the proposed regional mass transit system through the site, but the municipality and the Pennsylvania Environmental Council secured funding for a stormwater infiltration retrofit demonstration project at a municipal parking lot not far from the site. Meanwhile, the Nine Mile Run model includes informed broad environmental and infrastructure management initiatives and understandings. Ecological restoration is a major component of the new Pittsburgh Parks master plan. In Nine Mile Run’s Frick Park, downstream of the charrette sites, the US Army Corps of Engineers will initiate a $7.7 million aquatic ecosystem restoration program in the summer of 2001, funded by the City of Pittsburgh and the federal government under Section 206 of the Water Resources Development Act of 1996. Rivers Wet Weather Inc., a nationally funded wet-weather management demonstration program, notified Allegheny County communities that it will entertain funding requests for projects incorporating techniques illustrated by the charrette designs.

It makes good sense to manage precipitation as close to where it falls as is physically and economically feasible, using freely available natural processes to do the work of stormwater storage and treatment. By embedding sewer and watershed restoration in community revitalization, restorative redevelopment reduces or eliminates problems that public works agencies would otherwise struggle to solve in isolated efforts by downstream engineering.

Bruce Ferguson is a professor of landscape architecture at the University of Georgia School of Environmental Design. Richard Pinkham is an adjunct research scholar and consultant with the Rocky Mountain Institute in Snowmass, CO. Timothy Collins is a research fellow with the STUDIO for Creative Inquiry at Carnegie Mellon University in Pittsburgh.

This article is condensed from the report Re-Evaluating Stormwater: The Nine Mile Run Model for Restorative Redevelopment, published by the Rocky Mountain Institute, www.rmi.org. The complete report and a technical appendix are available at the Web site.

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