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Alternative suburban storm water management : Cranston, Calgary, Alberta Wei, Gillian Marie 1999

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ALTERNATIVE SUBURBAN STORM WATER MANAGEMENT: CRANSTON, CALGARY, ALBERTA by GILLIAN MARIE WEI B.Comm., The University of Alberta, 1994 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF LANDSCAPE ARCHITECTURE in THE FACULTY OF AGRICULTURAL SCIENCES THE FACULTY OF GRADUATE STUDIES We accept this thesis as corrforming to the reauired standard THE UNIVERSITY OF BRITISH COLUMBIA May 1999 © Gillian Marie Wei, 1999 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y sha l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s m a y b e g r a n t e d b y t h e h e a d o f m y d e p a r t m e n t o r b y h i s o r h e r r e p r e s e n t a t i v e s , i t is u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n sha l l n o t b e a l l o w e d w i t h o u t m y w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f Q^r^0^f>C kcH^C T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r , C a n a d a D a t e D E - 6 ( 2 / 8 8 ) ABSTRACT The alterations in the site layout design and economic cost implications of implementing storm water best management practices or BMPs on a suburban site in Calgary, Alberta were compared to the traditional suburban layout and storm water management used in new developments. The most suitable BMPs for the site were selected after analysis of the site's climate, topography, soil type and hydrology. An alternative site layout that integrated the BMPs into the community's design and function was proposed for comparison to the conventional site layout. The alternative site design and storm water management plan proposed for Cranston made extensive use of dry swales, pervious surfaces, and permanent wet ponds. The open space design sought to connect the suburb to the larger regional landscape and to create a distinct community identity based on landscape type while also functioning as part of the storm water management system. In comparison with the conventional site design, the alternative design reduced impervious surfaces by 3.5% or 5.1 hectares of the total site, while public open space increased by approximately 6% or 7.69 hectares. The number of house lots in each design was kept relatively even, with the alternative plan having a higher density due to a lower net developable area. Infrastructure capital costs of the alternative plan were found to be slightly lower than the conventional plan due to the reduction in paved surfaces such as roads and curbs and gutters. These findings imply that the monetary costs of implementing alternative storm water management techniques are comparable to the conventional storm water systems. However, the ultimate benefits of storm water BMPs are realized in the local ecology and the regional landscape as a whole. Key Words: alternative storm water management, best management practices, BMPs, suburbs, suburban development, Cranston, Calgary ii TABLE OF CONTENTS Page ABSTRACT i i LIST OF FIGURES vi LIST OF DRAWINGS vii ACKNOWLEDGEMENTS vii i 1.0 STATEMENT OF PROJECT INTENT 1 1.1 Project Goal 3 1.2 Project Objectives 4 2.0 METHODOLOGY 4 3.0 SITE CONTEXT - CALGARY, ALBERTA 5 3.1 Calgary, Alberta Canada 5 3.1.1 Climate 6 3.1.2 Sustainable Suburbs Study 7 3.1.3 Storm Water Management 8 4.0 CRANSTON, C A L G A R Y 9 4.1 Topography and Drainage 15 4.2 Vegetation and Wildlife 16 4.3 Soils and Geology 16 4.4 Site Servicing and Utilities 17 4.5 Storm Water 18 5.0 PRECEDENT CASE STUDIES 19 5.1 Rocky Ridge, Calgary 19 5.2 Village Homes at UC Davis, California 22 5.3 Mackenzie Towne, Calgary 24 5.4 Nance Canyon 26 5.5 Parking Lot Runoff, Portland Oregon 28 6.0 STORM WATER BEST M A N A G E M E N T TECHNIQUES (BMFs) 31 6.1 Impacts of Urbanization 31 6.2 Storm Water Best Management Practices 32 6.2.1. Non-Structural BMPs 34 6.2.2. Structural BMPs 36 6.2.3. Operational and Maintenance BMPs 43 iii Page 7.0 ENVIRONMENTAL IMPACTS OF BMPs 44 7.1 Control of Peak Discharges 44 7.2 Removal of Sediments and Pollutants 45 7.3 Promote Infiltration 47 7.4 Creation of Wildlife Habitat 49 8.0 ECONOMIC IMPACTS OF BMPs 49 8.1 Property Value 50 8.2 Infrastructure Costs 51 8.3 Maintenance Costs 52 9.0 SOCIAL IMPACTS OF BMPs 54 9.1 Recreation 54 9.2 Aesthetics and a Sense of Place 55 10.0 BMP TYPOLOGIES FOR CRANSTON : 56 10.1 Prairie Grassland 57 10.2 Prairie "Pothole" or Wetland 58 10.3 Prairie Waterway 61 11.0 CRANSTON SITE DESIGN 62 11.1 Alternative Site Layout Design 62 11.2 Zoning 63 11.3 Open Space 63 11.4 Storm Water Management 64 11.5 Streets 67 12.0 OPEN SPACE DESIGN 69 12.1 The Middle Green 70 12.2 The Prairie Pothole Park 71 12.3 The Southern Greenway 72 12.4 The Northern Greenway 72 13.0 INFRASTRUCTURE COSTS 73 14.0 CONCLUSION 75 BIBLIOGRAPHY 77 APPENDIX 1: RUNOFF VOLUMES 81 APPENDIX 2: VEGETATION A N D WILDLIFE SPECIES 84 iv Page APPENDIX 3: CONVENTIONAL A N D ALTERNATIVE P L A N 87 COMPARISONS APPENDIX 4: SWALE CAPACITIES 94 APPENDIX 5: INFRASTRUCTURE COSTS 96 APPENDIX 6: REAL ESTATE VALUES 99 APPENDIX 7: DRAWINGS 101 v LIST OF FIGURES Page Figure 1 Effects of Urbanization 2 Figure 2 Site Context Map 10 Figure 3 Aerial Photo of Site 11 Figure 4 Ownership Map of Site 13 Figure 5 Site Layout Design 14 Figure 6 Vegetation and Landscape Types 60 vi LIST OF DRAWINGS Drawing S1 Drawing S 2 Drawing S 3 Drawing S 4 Drawing S 5 Drawing S 6 Drawing S 7 Drawing S 8 Drawing S 9 Drawing S10 Drawing S11 Drawing S12 Drawing S13 Drawing S14 Drawing S15 Drawing S16 Drawing S17 Drawing S18 Drawing S19 Drawing S 20 Suburban Calgary Images Cranston Site Images Conventional Site Layout Alternative Site Layout Conventional Open Space Alternative Open Space Conventional Storm Water Management Alternative Storm Water Management Collector Street Residential Street Dry Swale Detail and Street Sketch Lot Drainage Conceptual Grading Plan The Middle Green Plan Middle Green Sections Prairie Potholes Plan Prairie Pothole Sections The Southern Greenway Southern Greenway Sections The Northern Greenway vii ACKNOWLEDGEMENTS During the process of completing this design thesis, the help and direction of my design coirirnittee members, Patrick Condon and Don Luymes of the Landscape Architecture department along with Dr. Ken Hall of IRE (Institute of Resources and Environment), was invaluable. I would also like to acknowledge the help and information given by Carma on the project site of Cranston. The information provided by the City of Calgary and the River Valley's Commission was also of great benefit to this thesis report. viii 1.0 STATEMENT OF PROJECT INTENT - INTRODUCTION As we enter into the next century and as our cities and towns continue to expand and grow, society is becoming more aware that such growth cannot continue indefinitely. In considering this "urban sprawl" one must look at the ultimate causes of the development - government standards, demand/supply economics, adherence to outdated building standards and even societal preferences. Why are the developments built the way they are? Are there opportunities for changing out-dated standards and preferences? Where do we even start? This thesis will look at one of the utilities that support our cities, storm water management, and how this utility may be altered in the suburban context to provide a more environmentally sensitive way of managing storm water in our cities. As well the concept of "beautiful infrastructure" will also be explored as it relates to storm water management in the landscape. Is it possible that a process we rely upon, a utility, be aesthetically pleasing in the landscape? Suburban housing developments often occur on the outskirts of cities and towns where there are still large tracts of open space available for development. Usually this open land is agricultural land that has been gradually been surrounded by other developments. Any new development alters the natural hydrological regime of a site (Figure 1). Impervious materials such as asphalt and concrete forbid natural systems from handling surface water runoff. It has been noted that a change of as little as 10% imperious cover on a site drastically alters the hydrologic cycle (Figure 1). We have engineered complex systems to whisk the storm water away - out of sight, out of mind. Along the way the storm water runoff collects and carries along with it the residues of our urban life such as oils and traces of heavy metals. But awareness has been growing as to the various negative environmental impacts of this practice. 1 25% Storm rvrvoff 43"*. Groundwater A 32% < 13% V Figure 1: Effects of Urbanization In most municipalities it is the engineering bylaws and zoning standards that ultimately dictate the form of new suburban developments - the profile of the street that must be maintained to provide the services demanded in any new development. One of the major utilities to be accommodated is the storm sewer system that will remove storm water runoff from the new development. When the other utilities and setbacks are taken in to account the result is a wide boulevard given over to the automobile. These wide streets are also designed to collect vehicles and move them around and out of the development as quickly as possible. Work, shopping and recreational facilities are often outside the community, requiring numerous car trips to provide the necessities of life. Roads that are engineered to move people as quickly as possible are also designed to move storm water away as quickly as possible. A complex system of pipes and drains collect storm water runoff from impervious surfaces and carries it away from the development. This reduces the risk of flooded basements and streets and inconvenience to the community. 7 Recently, a set of "took" has been developed to manage storm water in an alternative manner. These "tools" are typically called best management practices or BMPs for storm water management. The BMPs seek to manage storm water in a "sustainable" manner by: i) preventing non-point source pollution from occrurring in the first place, ii) using natural processes to treat the runoff, iii) allowing water to be in contact with the ground, where it can infiltrate and replenish groundwater supplies and maintain base flows for creeks, streams and rivers, iv) and by emulating natural systems in function and appearance . In order to move towards environmental "sustainability" in our urban and suburban developments, changes must be made in the way we build in the environment and in the way we relate to our surroundings. By altering the way in which storm water is managed, we may also provide ancillary benefits to the environment and the community. It may be argued that altering one piece of the sustainability "puzzle" also impacts other pieces in unanticipated ways. 1.1 Project Goal On a new suburban development site, to determine the form of the development if storm water best management practices (BMPs) are implemented into the community. As well, the impacts this new design would have on the social, economic and environmental aspects of the community. 3 1.2 Project Objectives • To graphically illustrate how the design of a new suburb in south Calgary would change when a set of storm water best management practices are implemented into the site layout. • To assess the economic implications of the new form within the community in terms of capital emplacement costs and economic cost-benefit. • To compare and contrast the conventional and alternative site layout designs with regard to imperviousness and open space. 2.0 METHODOLOGY The methodology for this design thesis will employ research and intuition in developing an alternative suburban design for Cranston. The methodology is comprised of the following steps: • Conduct a literature review of • available storm water management BMPs; • concept of "sustainable suburbs"; • City of Calgary context; • Current City of Calgary storm sewer management; • Economic costs of implementing BMPs. • From the literature available, select and analyze case studies of storm water BMP implementation; • From available literature, select the most suitable BMP types for the Calgary site; • Apply the selected BMPs to the street profile and site layout design of the site, creating an alternative site layout design; 4 • Compare and contrast the alternative site design to the conventional site design. This methodology, while following along the lines of a formal research paper, provides a foundation of information on which the graphic design of the site is laid upon. The information gathered in the methodology is applied to the design to make the design "richer" and more detailed. The final products of the above methodology will demonstrate how a community would look like and function if designed to manage storm water only in an alternative manner. Unless otherwise stated, all other utilities will not be altered in this thesis. 3.0 SITE CONTEXT - CALGARY, ALBERTA The project site is a new suburban community, called Cranston currently under construction in southeast Calgary, Alberta. 3.1 Calgary, Alberta, Canada The larger context for the project is the city of Calgary. Calgary is a city of almost 1 mulion people located in the western Canadian province of Alberta. Located in the foothills to the east of the Rocky Mountains, Calgary is in close proximity major recreational areas such as Banff National Park and the Kananaskis, which provide year-round recreational opportunities (skiing, hiking, rock climbing, etc.). Two major rivers, the Bow and the Elbow, run through the city, providing topographical relief in the city boundaries (Klivokitis & Thomson, 1987). Most of the land surrounding the city is or has been under agricultural cultivation. The slightly rolling Prairie terrain, combined with the rich Chernozemic soils of the mixed grassland ecology, have made the region prime agricultural land. 5 The past few years have seen the city's rapid growth due to the resurgence of the natural resources sector in the province, namely oil and gas. Calgary's population is expected to grow to 1.25 million by the year 2024 (CCP, 1998). This rapid growth has caused a huge demand for housing, resulting in housing shortages and sharp price increases in real estate. Calgary is long on its north-south axis, roughly 34 kilometers long, with developments now reaching to the extreme north and south boundaries of the city. Calgary has several "satellite" communities surrounding its boundaries such as Airdrie, Cochrane, Okotoks and Chestermere that are also expanding out into the prairie landscape. 3.1.1 Climate Calgary is a winter city; the winter season runs to over 180 days per year, longer than any other Canadian city. The winter however, is broken up by the presence of chinooks, warm westerly winds that bring unseasonable wanning to the region. The temperature ranges during a chinook can be extreme. For example: one day in 1988 the mean morning temperature was +14°C and mean afternoon temperature was -24°C (Klivokioits & Thomson, 1987). Chinooks can last anywhere from one day to two weeks and also create large amounts of meltwater that must be handled by the storm sewer system. The chinooks reduce the amount of snow that accumulates on the ground and often during the winter there are periods of time where there is no snow cover on the ground. These extreme temperature changes also wreak havoc on the vegetation in the region as the plants begin to deacclimate in the warmer temperatures and are damaged by the following cold temps. 6 Summers in the city are generally dry, but summer thunderstorms and hailstorms do occur. Summer temperatures routinely reach into the mid-twenties (Celsius) with plenty of sunshine (Environment Canada, 1999). The average annual precipitation in Calgary is approximately 400mm. Average annual rainfall is 30TJmm (Environment Canada, 1999), with June being typically the wettest month of the summer. Ehiring the average large rain event (thunderstorm or hailstorm), approximately 15mm-20mm of rain falls to the ground. The storms in Calgary tend to be quick and heavy, with most of the rain falling within 30 minutes (Appendix 1). 3.1.2 Sustainable Suburbs Study In 1995, the City of Calgary adopted the Sustainable Suburbs Study, which sets out a "comprehensive package of planning policies, requirements and guidelines that respond to these issues [long term fiscal, social and environmental sustainabiHty]" (CCP, 1998). As a planning document for new suburban developments the Study provides policies and design guidelines for creating more "sustainable" developments in Calgary (SSS, 1995). Some objectives of the Study are to create more livable communities with employment opportunities and recreational facilities and to create more varied communities in terms of housing types and population. These "sustainable" communities attempt to develop living spaces that are still desirable to people from an economic standpoint while lessening the overall impact of suburban development on the surrounding environment and region as a whole. 7 3.1.3 Storm Water Management Currently, the City of Calgary requires storm sewer systems to be designed for the once-in-five-year event. The conventional storm sewer system of pipes, drains and catchbasins is in use throughout most of the city. Storm sewer discharges must be in accordance with the regulations laid out by the Province of Alberta. According to regulations set out by Alberta Environment, on most new developments, the post-development rate of runoff must not exceed the predevelopment rate of runoff. In Calgary, this is achieved through the use of wet and dry detention ponds to retain storm water runoff and to control the release of the runoff into the main system. These ponds do not treat or remediate the storm water in any way but rather only hold it for later release. Many of these ponds have been turned into "lakes" and are often prominent features in the landscape. The City does recognize the need to manage storm water runoff so as to reduce the negative impacts of runoff in the environment. As stated in the City's "Policy on Stormwater Lakes" (1981), some major objectives of storm water management are: " T o encourage e v o l v e m e n t o f s to rm w a t e r m a n a g e m e n t so lu t ions w h i c h w i l l m i n i m i z e de t r imen ta l impac t s o n s t ream wa te r q u a l i t y f rom res ident ia l surface d ra inage . . . T o ensure that the s to rm wate r d ra inage s tudies assess the re la t ive impac t s o f a l te rnat ive d e s i g n so lu t ions w i t h i n bo th the p r o p o s e d s u b d i v i s i o n a n d the o v e r a l l b a s i n - w i d e d ra inage sys tem." As well, in the Sustainable Suburbs Study, there is a policy regarding storm water management in the new suburbs. "Alternative methods to traditional storm water management techniques must be examined in terms of appropriateness and cost, for us in new communities." (SSS, 1995). Recently, two or three pilot constructed wetlands have been implemented in Calgary and the city continues to monitor those projects. The use of wetlands to remediate storm water is 8 relatively new to Calgary and thus the verdict is not in as to their overall success. One developer was attracted to the wetland as it was an extra marketing tool for the new community as well as being an existing natural feature of the site. However, on a citywide scale, alternative storm water management techniques are not widespread. 4.0 CRANSTON, CALGARY In June, 1998 the city approved the Community Plan for Cranston and construction on the site is under way. The site is on the extreme south end of Calgary, just south of the Fish Creek Provincial Park (Figure 2). The site is bounded to the north by Highway 22X (Marquis of Lome Trail), to the west by a prominent escarpment and the Bow River Valley and to the east by a future extension of the Deerfoot Trail (Figure 3). 9 Figure 3 Aerial Photo of Site Source: Stanley Tech Report Cranston Phase 1,1998 1 ! The total Cranston site will be developed in phases, Phase 1 being the site for this project. Ownership of the total Cranston community site is divided among three (3) owners: Carma Developers, Burns West Corp. and Soutzo. The total planning area for the Cranston community is approximately 661 hectares and will accommodate over 22,000 people (Figure 4). Phase 1 of Cranston is approximately 153 hectares of land at the northern edge of the site owned by Carma Developers. Carma, who also planned the nearby neotraditional community of Mackenzie Towne are also developing Cranston Phase 1. Cranston, however, will not be developed along the same lines as Mackenzie Towne as the sites are very close to one another and competition may arise due to this close proximity. Population projections for Phase 1 are 9,900 people in mainly single-family residential dwellings, with some low and medium density dwellings (CCP, 1998). Two elementary/junior high schools (public and Catholic) have also been planned in the site. Each school site is approximately 4 hectares in area and serve as "neighbourhood nodes" (Figure 5). The Community Plan for Cranston calls for the development of a community core along with smaller neighborhood nodes as a means of creating a community identity and to reduce to amount of automobile trips within the community. The neighborhood nodes would consist of higher density housing, a transit stop, recreational open space and in some nodes, commercial space. The Plan calls for no residence to be farther than 400m away (approximately 5 minute walking distance) from a neighborhood node, therefore providing access to the larger community and providing a destination point for residents. 12 Figure 4 O w n e r s h i p M a p of Crans ton Source: City of Calgary, Cranston Community Plan, 1998 13 The escarpment will be maintained as public open space and a trail along the escarpment edge will be part of a larger regional greenway. 4.1 Topography and Drainage The major feature of this site is the noruVsouth escarpment that runs along the community's entire western edge. The escarpment provides spectacular views to the Bow River valley below the site and to the Rocky Mountains in the west. Calgary's downtown core may also be seen from the site. The site is relatively flat with some rolling terrain and gently slopes from the southeast to the northwest with elevations ranging from 1,040m to 1,058m above sea^ level (CCP, 1998). Some natural depressions on the site appear to be seasonal wetlands. There are permanent wetlands just to the north of the site boundary . The site naturally drains towards the river valley as the escarpment drops significantly from the plateau to the valley bottom. The escarpment is quite steep with slope in excess of 45%. The large ravine on the escarpment is the result of natural drainage processes; all water on the site wants to go the escarpment. There are also several permanent springs within the ravines of the escarpment (CCP, 1998). No development is planned for the escarpment as it has been classified as an environmentally significant landscape feature within the city. 15 4.2 Vegetation and Wildlife The predevelopment vegetation on the site is mainly grass. The site had been under agricultural cultivation and therefore already disturbed by human activity. Tall shrubs and trees occur on the sides of the escarpment and in the river valley bottom. Given the climate of the region, the larger shrubs and trees generally occur in areas where moisture is present. Trembling aspen (Populus tremuloides) and balsam poplar (Populus balsamifera) are the dominant native trees in the area. In exposed areas where sun and lack of moisture combine to create a harsher microclimate, prairie grasses dominate. Most of the plant cover on the site has been removed due to construction activity on the site. This requires the addition of plant material such as street trees to be added once development has occurred on the site. Carma gives each new homeowner one tree to begin their landscaping but otherwise has no other input into the landscaping. The overall landscape plan is done by a landscape architect - in this case Lombard North in Calgary. The Bow River valley below the site is an important wildlife corridor for both mammals and bird species. As well, the Bow River has significant fisheries value for brown trout and rainbow trout. The regional pathway along the escarpment connects to Fish Creek Provincial Park. The land in the river valley is owned by the provincial government and has been classified as environmentally significant and will not be developed. 4.3 Soils and Geology 16 The soils on the site are mainly gravel, silt, sand and some clay, providing for a well-drained site. (CCP, 1998) The layer of topsoil on the site is classified as Loamy Sand and therefore drains quickly and is suitable for agriculture. Although generally flat, the pre-development landscape also consisted of small hummocks and depressions on the site. Previous use of the plateau was mainly limited to fanning and some parts are still under cultivation. The valley bottom south of the project site has been the site of extensive gravel extraction activity and some of the valley floor has been reclaimed from this activity. The subsurface geology on the site is stable and generally poses no constraints to development on the site. It is generally composed of silty clay soil and the depth to the groundwater table is generally 16m to 17m below the surface (Whitford, 1998). 4.4 Site Servicing and Utilities Cranston will be serviced by extending existing services into the site. Water, electricity, sanitary sewers will be extended from the existing community of Mackenzie Lake into Cranston. Future expansion of the sanitary sewer system will be handled by the proposed Pine Creek Sewage Station to the southwest of the site (CCP, 1998). A section of land to the adjacent to the north edge of the site will maintained as part of the Province's Transportation and Utility Corridor. This TUC provides for the future expansion of roads and utilities that may be required as the city continues to grow. 17 ConuTtunity services such as fire and police protection, medical care, libraries and social services will be handled by existing facilities at the southern end of Calgary. 4.5 Storm Water Storm water on the site will be collected on site through conventional pipes and drains and conveyed to a 2.4m diameter outfall pipe into the Bow River. The catchment area of this outfall pipe actually extends beyond the boundary of the site to encompass 1200-1400 acres. The outfall pipe is located in the prominent ravine on the edge of the site and is one of three that is planned for the entire Cranston community. The outfall pipe actually crosses provincially-owned land on its way to the Bow River (Morrison, 1999). The original owners of the land had an agreement with the city that allowed them to direct water into the Bow River; this original agreement was "grandfathered" into Carina's development plans, thereby eliminating the requirement for the development to manage storm water on site (Froese, 1998). A wet pond was originally considered for the site but studies done by Carma found that the most likely spot for a wet pond would be along the edge of the escarpment (following natural drainage patterns). This raised concerns as to the stability of the escarpment if a wet pond was placed there, but more importantly, the land along the escarpment is the most valuable in real estate terms due to the expansive landscape views and location adjacent to the escarpment edge. Locating a wet pond on the escarpment would reduce the amount of prime real estate available along the escarpment. Storm water management on the Cranston site is limited to an 18 oil skimmer that has been installed at the last manhole connection before the outfall (Morrison, 1999). Given that some alternative storm water methods (wet ponds) have been studied by the developer and found to be less cost effective and otherwise unsuitable to the site, other best management techniques should be explored on this site. At present, storm water management is minimal and any improvement in the system would have a corresponding improvement in the environmental condition of the region. For example, implementing a BMP that removes the large sediment pollutants from the storm water runoff before it enters the Bow River has a definite impact on the river's health. In order to be attractive to the developer and the city, proposed storm water BMPs should be both economically and environmentally feasible. 5.0 PRECEDENT CASE STUDIES As the use of storm water best management practices is a fairly recent occurrence, projects that have implemented these BMPs should be studied to evaluate the success or failure of these BMPs in the "real world" and to evaluate the place of these BMPs in the community. 5.1 Rocky Ridge, Calgary, Alberta This case study concerns a new subdivision in northwest CalgaryrSinular to the Cranston subdivision, Rocky Ridge also has extensive views of the Rocky Mountains to the west of the city and the development of the site took advantage of these spectacular views (Van Duin, et al, 1995). 19 However, unlike other subdivisions in the city, Rocky Ridge utilized an existing natural feature as part of its storm water management system. The predevelopment topography included numerous depressions or wetlands. These wetlands provided important wildlife habitat and nesting grounds for waterfowl. Rather than fill these wetlands and replace them with more standard dry or wet ponds, the wetlands were integrated in to the community's storm water plans. Retaining the wetlands also provided more economic, environmental and social benefits for the community than a standard dry pond. The economic benefits include the lot premium that could be realized from the lots closest to the natural feature, the reduction in the earthworks costs when compared to installing a wet or dry pond and the natural area as a marketing tool for the community. The wetlands provide environmental benefits in the form of improved water quality and wildlife habitat. Rather than simply holding the runoff, the wetlands also serve as biological filter for the water. Although development and the changes in the hydrologic cycle have impacted the biodiversity of the wetlands, there is still some wildlife present in the area. It could be argued that less wildlife is still preferable to no wildlife at alL Social benefits for the community include recreational and educational benefits and the perception of being "kinder" to the environment. This type of storm water management plan requires site sensitivity: what's happening on the site and how can the natural feature of a site be integrated, enhanced or utilized. 20 As with other cases of alternative storm water management, cooperation between all stakeholders is imperative. In the Rocky Ridge case, the developer was willing to try this method, as it would provide them with economic savings and a unique market niche. The City of Calgary was also willing to consider storm water management alternatives, as the wetlands The delicate ecological balance of the wetlands required the input of specialists such as biologists as well as the structural input of engineers to ensure that the wetlands would be affected as little as possible. Future residents of the subdivision were given an information package from the developer as part of a public education on the environmental benefits of having the wetlands within the commuruty. All of these stakeholders must cooperate in order for a project such as this to come into fruition. This case study also emphasizes the importance of on-going maintenance and monitoring of the system to ensure long-term efficiency and viability. The system has 5 years in which to prove its effectiveness; if it is not effective, the City will require the installation of a standard dry detention pond in place of the wetlands. Another point raised in the case study was who will ultimately pay for the maintenance and monitoring of the project. In this case the City of Calgary will monitor the wetlands on a limited basis. But there is no funding available for more in-depth studies to be done. were a unique feature worthy of preservation. 21 5.2 Village Homes at UC Davis, California The Village Homes community as a whole combines a number of sustainable systems within a small area (Thayer, 1994). The community seeks to be "restorative" or "regenerative" (Lyle, 1994) by creating living spaces that seek to limit the impacts on the surrounding environment. The storm water management system within the community is a more "natural" one compared to the traditional methods of conveyance such as storm drains and pipes. A system of vegetated swales run throughout the community to collect storm water runoff (Lyle, 1994) and hold the water until it either infiltrates into the soil or evaporates. This system provides economic, environmental and social benefits to the entire community. Economically, this "natural" runoff collection system costs less to implement than the traditional conveyance method of pipes and drains. The costs of the pipes and the costs of the excavation to install those pipes are not applicable in this type of system; there simply isn't anything structural to install other than small check dams and weirs within the swales to encourage ponding. The environmental benefits of the "natural" system over the traditional method are also notable. The vegetation around the swales provide habitat for a number of bird species as well as amphibians and insects (Thayer, 1994). The vegetated swales also filter any sediments or pollutants from the runoff thereby improving water quality before it enters the groundwater table. By allowing the water back into the earth, the underlying groundwater supplies are replenished. 22 The runoff from the paved surfaces is directed to one of the many curb cuts along the road and from the road into the swale system. The water does not have to travel long distances before it is collected thus decreasing the velocity of the water as it enters the swale. Lower water velocity reduces the likelihood of erosion in the swale. The velocity of the water is further reduced through the use of check dams and weirs that encourage ponding of the water. The roofs of the homes drain on to vegetated surfaces that allow the water to infiltrate into the soil rather than runoff into the street. The swales are close to the back doors of the houses, bringing this natural function closer to the people of the community. As the swales are not deep, they provide recreational opportunities when they are wet (after a rain event) and dry for the children of the community (Thayer, 1994). Bike paths that run parallel to the swales connect open spaces such as playgrounds (Ferguson, 1998). The residents of the community undertake maintenance of the "natural" system. The community is divided into clusters of 8 houses; each housing cluster manages their own section of the swale system, experimenting with the design, vegetation and surfaces (Ferguson, 1998). This "hands-on" approach to maintenance gives the residents a sense of ownership and provide the community with a diverse array of open spaces to enjoy (Ferguson, 1998). It must be stated that the Village Homes community is quite unique as a housing development. It arose from a combination of events and people that favored the development of a more "sustainable" community. Community involvement is crucial to the success of Village Homes; often this is not possible in other housing developments. However, from the standpoint of a storm water management system, Village Homes demonstrates that storm water management 23 practices do not have to be large to be effective. By allowing the water to do what water does best - infiltrate and evaporate and by keeping the water in contact with the ground as long as possible, the storm water system in Village Homes has no runoff leaving the site (Ferguson, 1998). The water that falls on the community is used within the community to nurture the ecological systems and enhance the social systems of the place. 5.3 Mackenzie Towne, Calgary, Alberta Mackenzie Towne is the first neotraditional community planned in Canada by Duany-Plater-Zyberk and also developed by Carma in Calgary, Alberta. The community was first planned in 1990, with the first phase of Mackenzie Towne finished in 1995. The total site encompasses 970 hectares with the first phase covering 88 hectares (Epp, et al., 1999). Mackenzie Towne is unique in the Calgary suburban context as it was planned and designed to emulate a "New Town", complete with town center and a grid street system. The community plan for Mackenzie Towne calls for employment, recreational and retail opportunities to eventually be built within the community, in essence creating a "complete community". Like any other suburban development though, the neighbourhood will be phased in over time, so it will be at least 10 years before the community's vision will come into fruition. The community's main street is laid out in formal axis and terminated by a major civic space on either end (Epp, et al., 1999). The town center contains some retail and commercial services in the form of a corner convenience store and a dental office a short walk from anywhere in the existing neighbourhood. However, once the entire community is built, the town center will NOT be within an easy walking distance to approximately 40% of the residents (Epp, et al., 24 1999). The town center is positioned to take advantage of the close proximity to the rnain road into the commiinity and is therefore not in the geographical "center" of the commiinity. While still a predominantly smgle-family residential neighbourhood. Mackenzie Towne offers a variety of housing types not usually found in Calgary suburbs. Housing choices range from smgle-family detached homes, to low-rise apartments and townhouses. The building form is regulated by architectural guidelines that seek to promote the appearance of an old-fashioned town: front porches, verandas, white picket fences. There are no garages fronting the streets; all covered parking is in the rear of the lot accessed by back lanes. A large wet pond, called Inverness Pond, handles storm water for the Mackenzie Towne community. This pond has been landscaped with trees and shrubs and also provides the community with some recreational benefits. A pathway circles the pond and a large sign informs the community of the pond's function in the landscape. The community greenways and sports fields within the community are also available for ponding water during large rain events (Epp, et al., 1999). Residential streets are somewhat narrower in Mackenzie Towne and the homes have reduced setbacks from the street compared to typical suburban developments. Sidewalks are on both sides of the streets for pedestrian accessibility rather than only on one side of the street. Shorter street blocks also serve to slow traffic while creating better connections through the community. Consumer response to Mackenzie Towne has been good. The community seems to be popular with young families who are looking for the sense of community provided by the neofradmonaUy-planned neighbourhood. With the diversity of housing options comes the 25 opportunity for population and income diversity. Mackenzie Towne is an example of an alternative suburban development type that can be accepted by developers and municipalities. 5.4 Nance Canyon, Chico, California : Moving towards an environmentally sustainable "New Town" In 1991, Robert Thayer's design firm CoDesign and DPZ Associates (Duany Plater Zyberk) began to plan and design a "'New Town" in Nance Canyon. From the outset, the owners and developers of the project sought to produce the most environmentally responsible town possible (Thayer, 1994). Most of the design challenges arose from water: how to handle it on site, how to maintain the delicate ecological balance of the site and how to make the most of this scarce resource. The designers had to take into balance the desire to preserve the ecological integrity of the site with the need to protect the community from fire (Thayer, 1991). The site layout of the New Town was kept away from the most ecologically sensitive areas such as the mesa tops and the vernal pools that captured rainwater after storms and allowed the water to infiltrate back into the soil. The design of the community and the design of the water systems had to work in conjunction with the natural processes of the site. Storm water would be captured and used entirely on the site. The storm water would be part of the water supply for the constructed wetlands and would be allowed to infiltrate into the soil or evaporate naturally. The drainage network would be maintained as open space, to link together the community through bike and footpaths and also providing more wildlife habitat and opportunities for recreation (Thayer, 1991). 26 Human wastewater from the community would be treated in the constructed wetlands that also double as wildlife habitat. The cleansed water would then be used to irrigate lawns, school grounds and parks. The concept of "hydrozoning" was used to detenrtine the landscape water use within the community therefore the amount of land to be irrigated in the community was kept to a minimum, limited to those areas that were to have the most human activity occurring in them. "Primary hydrozones" are the areas where people live and play and have the most direct contact with the land: lawns, gardens, and schools. "Secondary hydrozones" are areas that have less direct people contact but still provide aesthetic enjoyment such as flower beds. These hydrozones need half as much water as primary hydrozones. "Minimal hydrozones" are those areas that use drought-tolerant or native vegetation, which require minimal watering to be viable. "Elemental hydrozones" are those area that do not need any irrigation such as gravel lots and undisturbed natural areas (Thayer, 1991). By determining hydrozones in the planning stage of a development, the overall demand for water may be significantly reduced. The water used for irrigation can be reclaimed water from greywater or storm water sources which reduces the need to use high-quality drinking water to irrigate the landscape (Thayer, 1994). Unfortunately, the Nance Canyon development was not built as originally planned due to an economic downturn in the region. However, it demonstrates that a more sustainable type of living is possible. It is an example of site planning that is site-specific and sensitive, using the unique characteristic of the site to inform the design and function of the community. 27 5.5 Parking Lot Runoff: Portland, Oregon Conventional parking lots are constructed of impervious materials such as asphalt and concrete. The surface of the land is efficiently sealed off from the rest of the environment, particularly water. Rainwater, instead of infiltrating into the soil, now runs along the impervious surface of the parking lot, picking up pollutants and urban debris and carrying them along to the nearest storm sewer drain. The volume of water that used to sink into the ground to replenish natural systems is now whisked away, polluted, to another location. Large expanses of asphalt surrounding suburban malls and developments provide parking for the shoppers. The parking lots are usually designed to hold the maximum amount of cars for peak shopping seasons such as Christmas. So for most of the year, a large portion of the parking lot is not used. An example of a "greener" parking lot can be found at the Oregon Museum of Science and Industry (OMSI). The aim of the parking lot design is to filter the storm water runoff of pollutants before it can enter into the groundwater. Instead of the usual catchbasins and drains that carry away storm water runoff, the water is channeled to seven bioswales within the parking lot. These bioswales are designed to hold runoff and convey it as slowly as possible to an outlet drain at the lowest point of the bioswale. This outlet drain empties into the nearby Willamette River. The linear bioswales features such as river rocks and small check dams that slow the water, encouraging it to pond, which gives the water time to soak into the ground (Thompson, 1996). As the water infiltrates into the ground, the poUutant<:arrying sediments are left behind and do 28 not enter the groundwater. The vegetation in the bioswales is mainly native wetland species such as cattails and bulrushes that also help to filter out the pollutants in the runoff. This parking lot was made possible by the design of Tom Liptan, ASIA and Murase Associates. The Museum requested that the vegetation in the swales would richly interpret the water that fell on the site (Thompson, 1996). The design called for the shortening of the parking stalls to create more space to devote to the bioswales. Computer modeling of the site revealed that the bioswales could infiltrate .83 inches (2.1 cm) of rainfall in a 24-hour period (Thompson, 1996). Given this amount of water, the bioswales would be able to handle over 75% Portland's annual rain events. The runoff from larger storms is carried to the Willamette River through the outlet drain in each bioswale. This alternative parking lot design saved $78,000 when compared to a conventional parking lot (Thompson, 1996). This cost saving makes the parking lot bioswale economically attractive to other developments. The bioswales must be properly designed and maintained in order to be both cost effective and environmentally effective. As well, the bioswales may not be suited to every site. Much depends upon the existing soil condition and climate of each site. Another method of handling the runoff from parking lots is permeable paving. Permeable paving could be used in those areas of the parking lot that receive limited use throughout most of the year. Permeable paving could help to reduce the amount of runoff that leaves a parking lot and may also provide some filtering benefits. 29 These alternative methods of parking lot drainage still need to be accepted by the public. These methods need the interest and the commitment of the landowner and developer as well as the technical expertise of landscape architects and engineers in order to be successful. 3 0 6.0 STORM WATER BEST MANAGEMENT PRACTICES (BMPs) 6.1 Impacts of Urbanization The urbanization of a site can have far-reaching impacts for the rest of the natural environment. The increase in impervious ground cover in new developments such as asphalt and concrete, hampers the ability of the soil to accept water through infiltration and also increases the amount of surface water runoff leaving a site. Excess storm water is carried away from buildings and roads through an efficient system of pipes, drains and catchbasins. Between rain events, these impervious surfaces accumulate traces of heavy metals and other pollutants such as oil and grease. During rain events, these pollutants are washed away by the storm water runoff into the system of underground pipes and drains. Once the runoff has entered a pipe, it is carried to a "receiving body of water" or discharge point and is always dirtier than when it fell to the ground. This "non-point source" pollution has had a devastating effect on natural ecosystems throughout North America (USEPA, 1995). The increase in the volume of runoff can cause erosion in the downstream receiving bodies of water as well as aid in the transportation of an increased pollutant load (USEPA, 1995). All of the runoff from a site is concentrated and the velocity of the water discharging into the receiving body of water can be very high. The smooth pipes of the storm sewer system do not slow the water; in fact they are designed to transport the water away as quickly as possible. The increased velocity of the water increases its erosive power which can damage the receiving body of water's ecosystem. Along with increased erosion, there is also the increased risk of downstream flooding that is also connected to the increased volume of water that leaves developed sites. The runoff must go 31 somewhere when it is discharged. In natural systems, most of the water that falls to the ground is able to infiltrate into the soil. Little of it leaves as surface runoff and natural systems can handle these small amounts of runoff. With more impervious surfaces there is less pervious areas on the site that can allow water to soak back into the ground, thereby creating more runoff than natural systems can effectively handle. Impervious surfaces also alter the hydrologic regime of a site. With less water being able to infiltrate into the soil, groundwater tables are not replenished to predevelopment levels. Water that would have soaked into the ground is now transported away from the site. Groundwater levels are important in mamtaining the base flows for creeks, streams and rivers. When the groundwater supply is reduced or depleted, then the water features that rely upon them are also impacted. In the short term, natural systems may be able to compensate for the changes in the hydrological regime but in the long term, they will inevitably be destroyed. Remediation of these ecosystems will be fruitless unless the ultimate cause of the degradation has been addressed. 6.2 Storm Water Best Management Practices Storm water "best management practices" or BMPs are a set of tools intended to provide alternative methods of controlling and mitigating the impacts of storm water runoff listed above. These BMPs, as they are commonly known, can be classified into three broad areas: operational and maintenance, structural and non-structural BMPs (Dayton & Knight, et al., 1998). 32 These three broad areas contain a variety of methods to aid in the quest for improved water quality in our increasingly urban world. Examples of operational and maintenance BMPs include the maintenance plan for structural BMPs and monitoring of the storm sewer system to prevent illicit discharges. Structural BMPs are the actual facilities used to control and mitigate storm water, for example wet and dry detention ponds, oil/grit separators and constructed wetlands. Nonstructural BMPs take the form of legislation and education to prevent the pollution of the runoff even before it happens. BMPs are not 100% effective on their own; for the maximum benefit to the environment and for maximum efficiency, a combination of nonstructural, structural and operational BMPs must be used as part of an integrated storm water management plan. Without one part of the total three, the integrated storm water management system wil l not function at its maximum potential. It is not enough to simply install a wet pond without also implementing a regular maintenance plan. As well, if there are no legislative controls to prevent the pollution from occurring the first place, then the BMPs simply become a stopgap measure with no long-term benefits to be gained for water quality and quality of life for the community at large. Selection of BMPs for a site is primarily dependent on the site's unique conditions such as climate, soil, and hydrology. It is these site conditions that wi l l ultimately dictate the type and scope of the BMPs that may be utilized. For example, the underlying soils and geology of a site wil l limit the amount of infiltration that may take place. Soils may also affect the selection of the most suitable location for certain BMPs. Economic constraints also dictate which BMPs may be used; some BMPs require large amounts of land (example: wet and dry detention ponds) that may not be available in a preexisting development and would be cost-prohibitive to implement. 33 Selection of BMPs requires detailed site analyses to be done as to the physical constraints that may limit the choice of structural BMPs but also entails a knowledge of the municipal regulations and legislation surrounding storm water management. Selection of BMPs is also dependent upon economic and social factors. The addition of some structural BMPs like wet ponds and constructed wetlands often offer economic and recreational benefits to the community. Property values of homes near to such features are often higher than those of homes farther away from the water feature and without a view (USEPA, 1995). However, the same structural BMPs may be unattractive to the community due to perceptions of "messiness" and the presence of pests such as mosquitoes (USEPA, 1995; Tourbier, 1994; Nassauer, 1995). BMPs do not exist or function within a vacuum. They require the interest and the input of the legislators, developers and the community at large to be the most effective and to have a positive impact on the environment. The BMPs work together as a set; one BMP alone cannot provide all of the environmental, economic and social benefits of BMPs. 6.2.1 Non-Structural BMPs Nonstructural Best Management Practices are implemented to prevent the environmentally harmful effects of non-point source pollution from occurring in tire first place (Dayton & Knight, et al., 1998). The nonstructural BMPs rely mainly on design interventions in the initial stages of development planning and construction. These types of decisions must occur at the planning stage in order to have the most environmental benefit and for the developer to realize any cost savings. Sensitive site planning can result in the creation of a unique community and 34 may also be used as a selling point for the developer. Listed below are common types of non-structural BMP policies: • Preserve and protect key natural drainage and habitat features A detailed site inventory and analysis should be completed and the development site should be evaluated as to the existing environmental regime: existing watercourses, wet spots, vegetation, soil type and so on. These existing features may be used as part of an integrated storm water management system, instead of being considered constraints to development. They should be seen as opportunities for water quality protection and storm water mitigation while also providing quality of life benefits for the community. (See Section 5.1 Rocky Ridge case study). • Minimize the amount of impervious surfaces and eliminate direct connections between impervious surfaces Minimizing the amount of impervious surfaces reduces the amount of surfaces that generate storm water runoff in the development. Less impervious surfaces mean more pervious surfaces that allow water infiltration into the ground. More infiltration into the ground translates into less water leaving the site as runoff. Elimmating directly connected impervious surfaces lessens the velocity of the runoff flow: as the water flows over longer distances the velocity and the volume of water also increases, ultimately picking up more pollutants and sediments and causing the erosion of the receiving body of water. By eliminating long lengths of connected imperviousness, the runoff must flow over pervious surfaces such as lawns, through vegetated swales and filter strips before reaching another impervious area such as the storm sewer system (Urbonas, 1993). The water therefore has more opportunities to be in contact with the ground, thereby increasing the chances of 35 irifiltration into the soil (Ferguson, 1998). The vegetation provides some filtering benefits for the storm water runoff such as the removal of large sediments and evapotranspiration. These methods generally work best for the smaller, more frequent rain events rather than for the large design storm events. The larger storms would overwhelm these small systems. But in smaller rain events, less runoff would reach the storm sewer system - some of the volume having been mfiltrated into the ground. However, if the BMPs could handle 80% to 90% of rain events in a more "natural" manner, the negative environmental impacts of storm water would be limited to 10% or 20% of rain events rather than 100% of events as in a conventional storm sewer system. 6.2.2 Structural BMPs Structural BMPs are the physical devices used in mitigating the damaging effects of storm water runoff. There are numerous devices that aid in improving water quality, controlling peak water flows and reducing erosion caused by runoff. The use of theses structural BMPs assumes that the "damage" has already occurred and that the water entering these BMPs is already polluted or of enough velocity and quantity to harm the receiving body of water (Dayton & Knight, et al, 1998). Structural BMPs are the most visible BMPs in the landscape as they are commonly placed within communities and neighborhoods as permanent features (for example, wet ponds, dry basins, and swales). Structural BMPs can range in size from a large wet pond or constructed wetland of a half-acre in surface area to a small roadside wet swale only 2 meters wide. Structural BMPs can be vegetated or completely man-made, as in the case of oil/grit separators and water quality inlets (Dayton & Knight, et al., 1998). Examples of structural BMPs are wet 36 and dry detention ponds, vegetated filter strips, grassed swales, man-made wetlands, sediment traps and porous pavement. Wet retention ponds and dry detention basins are the most common structural BMP used in suburban developments. Dry Detention Basins Often dry detention basins are grass-surfaced and serve as play fields when not inundated with water during storm events. Typically dry detention basins hold the runoff for a period of 24 to 48 hours and release the water slowly, thereby reducing the volume of water entering the receiving body of water during the "first flush" of the storm. The "first flush" of storm water runoff usually carries the highest content of pollutants and sediments into the receiving body of water. The first 5 minutes of a rain event collect the sediments and pollutants that have accumulated on impervious surfaces such as roads and driveways and transport them quickly into the storm sewer system. Dry ponds can collect this "first flush" runoff and provide a short period of time for some of the sediments to settle out and sink to the bottom of the basin. Generally though, dry detention basins are not designed to hold the water for a long enough period of time to allow for significant water quality improvements (Dayton & Knight, et al., 1998). A dry pond simply holds the runoff from the subdivision and slows the water's release into the receiving system. The amount of runoff leaving the site will not change, only the amount and time over which it is released is altered through the use of dry basins. Wet Ponds Similar to dry detention basins, wet ponds are designed to collect and hold storm water runoff from rain events. However, wet ponds maintain a permanent pool of water between storm 37 events (Dayton & Knight, et aL, 1998). Similar to the dry basin, the excess water in the pond is released slowly over a period of time, usually 24 to 48 hours, so as to not overwhelm the receiving body of water. Wet ponds are able to hold water for a prolonged period of time thus allowing for sediment removal in the form of settling and pollutant removal in the form of biofiltering through aquatic vegetation that may inhabit the pond. However, also like dry basins, the total amount of runoff is not affected by the use of wet pond. The permanent pool of water allows for the opportunity for the pond to become a multi-purpose facility, not only providing water quality benefits but also providing the surrounding community with recreational and aesthetic value. Wet ponds may or may not be landscaped, but if the pond is landscaped, the vegetation surrounding and within the wet pond may also provide wildlife habitat within the community. An aesthetically pleasing wet pond may also add to the property value of adjacent homes and provide recreational opportunities in the form of walking and biking trails around its perimeter for the community (Lyle, 1994; USEPA, 1995). There are safety concerns with wet ponds. There have been reports of young children drowning in the standing pool of water (Ferguson, 1998). As well, without proper maintenance the wet pond may become a breeding ground for pests such as mosquitoes. Man-made Wetlands Man-made wetlands are similar in appearance to wet ponds in that both maintain a permanent pool of water between storm events. They do differ in the manner in which they receive their supply of water: man-made wetlands are generally not connected to the rest of the storm water management system; they are an "off-line" system (Kadlec, 19%). The flow control device that 38 is connected to the rest of the system controls the amount of water entering the wetland during rain events. The variations in the water level that could occur if the wetland was on-line could be very damaging to the delicate ecological balance of the wetland. Man-made wetlands provide many water quality benefits over those of wet ponds. There are a variety of wetland types such as surface flow, subsurface flow and the use of natural wetlands (Kadlec, 1996). Man-made wetlands treat storm water runoff through the use of vegetation and bacteria that use the pollutants in the water for their growth processes. Treatment wetlands for wastewater are more prevalent than wetlands only for storm water remediation but the biological processes are the same. There are a number of case studies that show the effectiveness of this BMP in removing many pollutants and treating wastewater (Kadlec, 19%). Man-made wetlands have higher construction and maintenance costs than most other structural BMPs but also provide many environmental, recreational and aesthetic returns. A man-made wetland may look very similar to a natural wetland and may attract many wildlife species and provide an area for passive recreation. Wetlands are very complex and are highly designed. Professionals such as engineers, biologists, hydrologists and other wetland specialists should only undertake the design and implementation of a man-made wetland. Infiltrariori: Vegetated Filter Strips and Grassed Swales Infiltration allows water to soak into the soil. Decreased infiltration of water into the soil is one result of development and one that ultimately affects the underlying hydrology of the site. The aim of vegetated filter strips and swales is to keep water in contact with the soil for as long as 39 possible to allow for the maximum amount of infiltration (Urbonas, 1993; Ferguson, 1998). Although these two BMPs are similar in that they both allow for infiltration, they differ in the fact that swales are designed to act as a channel conveyance system for water and filter strips are designed to hold water until it infiltrates or evaporates (Dayton & Knight, et al., 1998). Swales Swales are essentially an open conveyance ditch for storm water. Swales channel the runoff to another BMP such as a dry detention basin and are usually grass surfaced. They are commonly used at the edges of roads and lanes to collect street runoff and may take the place of conventional pipes in a storm sewer system, therefore reducing some of the infrastructure costs associated with irotalling a conventional system (Dayton & Knight, et al., 1998). Swales can also provide significant amounts of water storage due to the sheer quantity of swale length. There are 4 main types of swales that are currently used: i) Drainage channel - for conveyance of water only; ii) Grass Swale - normally dry between rain events; some infiltration of water; iii) Dry Swale - provides for more infiltration of water than a grassed channel; dry between storms; iv) Wet Swale - channel contains standing water between rain events; may be planted with aquatic vegetation. A relatively new type of swale that provides biofiltration benefits to the runoff is the dry swale with underdrain (Claytor & Schueler, 1996; Dayton & Knight, et al, 1998). The underdrain system removes excess water to prevent saturation of the soil surrounding the gravel-filled trench under the swale. This trench serves to store water underground until it can infiltrate naturally into the soil. The water level in the storage trench must reach a certain capacity before 4 0 the water can enter the underdrain and then to a secondary storm sewer system. However, the quality of the water that reaches the underdrain is improved from typical storm water runoff because it has been filtered through a layer of vegetation and soiL which removes large sediments and some pollutants. Swales can be very useful in emulating predevelopment hydrologic conditions. The volume of water held in swales can reduce the amount of water that leaves a site directly after a rain event. The water is in contact with the soil, promoting infiltration and the movement of the soil through the soil removes pollutants from the water. Filter Strips Filter strips are broad areas of vegetation that collect and hold runoff until it soaks into the ground (Dayton & Knight, et aL, 1998). Runoff from streets and driveways can be directed to these strips or channels in an even flow, to be dispersed across the surface of the filter strip. Water may be directed to these filter strips as a means of disconnecting impervious areas. The vegetation - grass, shrubs, even trees, slow the velocity of the water thus allowing infiltration to take place. As water is absorbed into the ground, there is less water that leaves the strip thus reducing the total amount of runoff from the site. Filter strips also help to remove some pollutants from the runoff. The filter strips may be areas of existing vegetation retained on the site after development and may create some wildlife habitat in the area (Dayton & Knight, et al., 1998). Retention of existing vegetation may also reduce some of the infrastructure costs of development by reducing excavation and removal costs. The strips may also be new vegetation strategically sited within the development to function at maximum efficiency. 41 Porous Pavement Porous pavement also allows infiltration to occur while providing a stable surface for human use. Porous pavement may be used in areas of infrequent or light vehicles use such as the edges of parking lots or back lanes. Porous or pervious pavement may be as simple as crushed gravel instead of asphalt for road paving or may be modular concrete blocks with grass growing in the cells. The goal of porous pavement is to reduce the amount of imperviousness in a development while still providing the structural support and functionality of those surfaces. The above list of structural BMPs is only a small sample of the took available to be used in developing an alternative storm water management plan. The implementation of any these structural BMPs requires detailed site analysis and inventory to select the most effective BMPs for the site's unique conditions. Common limitations of the structural BMPs are peraieability of the site's soil, watershed area to be served available land area, depth to water table, slope of the site and economic feasibility (Schueler, 1987). These structural BMPs are often more easily implemented into new developments rather than into existing neighborhoods due to costs of retrofitting the existing infrastructure. Each structural BMP does NOT accomplish all the objectives of water quality improvement, erosion protection and volume and velocity reduction. Structural BMPs are typically one part of an integrated system that utilizes a variety of structural, non-structural and operational BMPs to achieve the objectives. 42 6.2.3 Operational and Maintenance BMPs Operational and maintenance BMPs are essentially "good housekeeping" practices. These BMPs are an integral part of the long-term efficiency and effectiveness of structural BMPs. Operational BMPs are aimed at detecting and eliminating sources of pollution before they can contaminate the water. Whereas non-structural BMPs seek to prevent the pollution from occxuring on a planning level, operational and maintenance BMPs seek physical solutions in preventing pollution, removing sources of pollution on the ground, reducing opportunities for slope erosion and containing toxic spills before they come into contact with water bodies. Examples of operational and maintenance BMPs include a regular maintenance schedule for structural BMPs, street cleaning, detection of illicit connections to the storm sewer system and the reporting of any spills. These BMPs are effective in reducing or removing sources of pollution that may be picked up by storm water runoff. Regular maintenance of structural BMPs such as catch basins and sediment traps ensure that they function as designed. A maintenance schedule should be an integral part of any storm water management plan. For instance, a build-up of polluted sediments at the bottom of a sediment trap decreases the holding capacity of the trap. Less sediment can be settled out of mcoming runoff and the velocity of the runoff may actually scour out some of the collected sediment and carry the extra sediments to the receiving body of water along with the "regular" sediment load that was not settled out in the trap. It is evident that a combination of the three types of storm water best management practices can result in significant water quality improvement. By reducing the amount of pollutants created, 43 combined with methods to return water to the soil and to filter the water naturally and with regular maintenance and enforcement of the BMPs, the negative environmental impacts of storm water runoff can be mitigated. 7.0 ENVIRONMENTAL IMPACTS OF BMPs As implied in the above section, storm water BMPs can have a significant positive impact on the environment. The use of BMPs seeks to somewhat restore natural systems to their predevelopment state. These natural systems will never be exactly the same as before development but they can be less damaged by human intervention. It is our human development that alters the environment; to be "sustainable" it is also our responsibility to ensure that those impacts are as murimal as possible. 7.1 Control of peak discharges Some BMPs, structural and non-structuraL can control the amount of water being discharged downstream. The water is collected and held during a storm event and released in a controlled manner over a period of a few hours or days. In nature, bankfull discharges only occur once or twice a year but after development, bankfull discharges may occur as many as 6 times a year, jeopardizing the ecological stability of a downstream receiving body of water. (Schueler, 1987). "Bankfull" is essentially a flooding situation where the runoff entirely fills the stream channel. Such a scenario can cause the erosion of the stream banks or slopes thereby increasing the amount of sediments in the water and ultimately contributing to the ecological degradation of the ecosystem. 44 By controlling the peak discharge and releasing the water after the storm events helps to reduce the number of bankfull occurrences. The water is released slowly, avoiding the huge first "flush" of water from a storm. The water does not overwhelm the receiving body of water and the velocity of the water is slowed to prevent erosion from occurring. However, it has been argued that releasing the water over a period of time degrades the stream integrity by increasing the period of high flows through the stream. Instead of one huge gush there are several medium (but still detrimental) flushes over a period of days which does not . give the receiving body of water sufficient time to recover. Confrolling the peak flows also assumes that there is no reduction in the post-development volume of runoff. The increased amount of runoff from a development is only spread out over a period of time rather than being released all at once. 7.2 Removal of sediments and pollutants The storm water runoff is also contaminated with urban residues such as oiL grease and heavy metals from roads, driveways and parking lots. During a rain event, the water travelling along these smooth impervious surfaces picks up the accumulated oils and sediments that were deposited by human activity since the last rainfall. The runoff then carries these pollutants with it to the nearest storm water drain and once in the drain, to the downstream receiving body of water. Since this pollution is only carried when there is excess storm water runoff during rain events, it is classified as ''intermittent" pollution. Pollution on impervious surfaces can build up if there is a extended period of no rainfall, thereby creating concentrations of pollutants. 45 Some pollutants are only transportable when they have attached themselves to sediments such as dust and dirt particles. The sediment load carried by storm water runoff can also have negative impacts on the receiving body of water. Increased sediments in the water can decrease the amount of light for aquatic plants which also impacts the aquatic life that depends on those plants. Some BMPs can aid in the reduction of the amount of pollutants reaching the receiving body of water and can also aid in the removal of these pollutants through biofiltrarion. Some structural BMPs hold the storm water runoff long enough to allow some of the pollutants and sediments to settle out. Even detaining the storm water runoff for only 24 hours still allows for some water quality improvement as the larger sediments carried in the runoff settle out with the basins or ponds (Schueler, 1987). Other BMPs skim off the floating pollutants such as oil and others trap sediments and the pollutants that are carried on sediments before they reach the receiving body of water. The resulting "sludge" at the bottom of these BMPs must be cleaned out regularly in order to maintain maximum design efficiency. Such BMPs include water quality inlets, oil/grit separators, sediment traps and wet ponds. Vegetation may also be utilized to increase the amount of pollutants taken from the storm water runoff. Certain aquatic and marsh plants can filter the runoff and remove some pollutants. This process is also known as biofiltrarion and is commonly used in man-made wetlands to treat wastewater (Kadlec, 1996). 46 Non-stractural BMPs and operational BMPs can aid in minimizing the amount of pollutants on the impervious surfaces. Public education and legislation can make the community aware of the negative effects of pollutants in our water bodies. Street cleaning can reduce the concentrations of pollutants on the roads that can be picked up by storm water runoff. Minimizing the amount of impervious surfaces also minimizes the amount of surfaces that collect pollutants. But as Bruce Ferguson (1998) states: "Ultimately, the only way to prevent pollutants from accumulating somewhere in the environment is to stop generating them in the first place - the pollution problem is, at source, a problem of our way of life." 7.3 Promote Infiltration The ability of the soil to infiltrate water is impacted by the presence of impervious surfaces with urban and suburban developments. The total amount of water falling on the site is the same post-development as it was pre-development but the development's impervious surfaces prevent water from contact with the soiL reducing the amount of water that infiltrates into the soil. With less infiltration into the soil, the pre-development hydrologic regime is negatively impacted. Less water is available in the underground water tables as they are not be recharged from above. Lower groundwater tables translates into lower base flows for streams and other water features that are dependent upon groundwater sources for their flows (Schueler, 1987). Less water in streams and other water features leads to a reduction in the amount of vegetation and aquatic life sustained in those water features. Combined with an increase in polluted overland flows, the ecological balance of these water features is severely disrupted. 4 7 Some structural BMPs allow the storm water runoff to remain in contact with the soil for as long as possible in order to promote infiltration. Allowing some of the storm water to infiltrate into the ground promotes the recharge of groundwater tables and limits the negative impact on the site's hydrological regime Vegetated filter strips, swales, infiltration trenches, porous pavement and water harvesting are a few structural BMPs that allow infiltration to occur. To a certain extent dry basins and wet ponds also allow infiltration to occur, but on a more limited scale. Infiltration into the soil also reduces the amount or volume of water leaving a site. The amount of infiltration is dependent upon the BMP and depending on the siting of the BMP, infiltration may be minimal. Also, the soil acts as a filter for the storm water runoff, removing sediments and pollutants before they can contaminate the groundwater. Water soaks into the ground, leaving sediments and pollutants behind. Some pollutants may be taken up by the vegetation for use in biological processes (Kadlec, 1994). Most of the filtering in soils occurs in the top few inches of the soil layer (Ferguson, 1998). However, soil suitability and stability should be tested before the implementation of infiltration measures (Schueler, 1987). Some soils allow water to drain very quickly which does not allow for filtration of very soluble pollutants such as nitrates and gasoline (Schueler, 1987). Other soils, such as clayey soils are difficult to infiltrate into and would create undesirable pools of standing water. Increased amounts of water in the soil may lead to slop slumping and other stability problems. 48 Non-structural BMPs also play a part in encouraging infiltration. By minimizing the amount of impervious surfaces within a development, there would be an automatic increase in more pervious areas such as lawns and gardens to allow for infiltration. Minimizing the connections between impervious surfaces forces the storm water runoff to flow over pervious areas, thereby allowing for infiltration to occur and also slowing the velocity of the runoff. 7.4 Creation of Wildlife Habitat Wildlife habitat can be created by the sensitive landscape design of BMPs. Aquatic vegetation in wet ponds and wetlands, while serving a water quality improvement function by filtering the water, can also serve as food and shelter for species of waterfowl, amphibians and insects. Vegetated filter strips can also provide habitat and could be a means of retaining some of the existing vegetation on the site. As well, by controlling peak flows of water into delicate riparian areas, BMPs may also help to reduce the opportunities for erosion and stream corridor damage, thereby mamtaining ecological health and balance. The creation or maintenance of natural areas also benefits humans. People use natural areas for recreation and aesthetic pleasure. 8.0 ECONOMIC IMPLICATIONS OF BMPs All three types of BMPs can all have economic implications for a new or existing development. The implementation of BMPs is not necessarily more expensive than the conventional system, but rather takes more time in the planning and design stage. There is no fixed "formula" to apply BMPs on a site; every site is different and therefore the' BMPs used on one site will not necessarily be the most suitable ones to use on another site. As well, the same type of BMP, for 49 example, wet ponds, may have a completely different appearance from one development to another, making economic comparisons of property value and implementation costs more difficult. 8.1 Property Value The most common economic measure of storm water BMPs is property value. BMPs can have one of three effects on property value: raise property value, decrease property value and have no impact on value (USEPA, 1995). The BMPs usually measured for property value impacts are wet ponds and wetlands as they are permanent and unique features in the landscape. When sensitively designed and managed, these two BMPs may have the appearance of a natural system which then makes the BMP more attractive to people. Humans tend to prefer water features in the landscape; water features can, provide aesthetic pleasure and recreational opportunities for the community (Tourbier, 1994; Ferguson, 1998). As well the proximity of a property to a water feature does have a measurable economic impact on the value of that property. Lots located adjacent to water features and lots with views of water features often sell for a premium over those lots that do not have these amenities (Tourbier, 1994; USEPA, 1995). The supply of such lots is limited and demand is high therefore increasing the value of the property. A study done by the National Association of Home Builders in the United States indicates that "whether a beach, pond or stream, the proximity to water raises the value of a home by up to 28 percent" (USEPA, 1995). In a case study of the Sale Lake subdivision in Boulder, Colorado revealed that lots located adjacent to a wetland sold for up to a 30 percent premium over lots that were not close to the wetland (USEPA, 1995). 50 Another case study involved the use of a wet pond from Alexandria, Virginia. The "lake" was used as a marketing tool for the new development of Chancery on the Lake. It was found that lots fronting onto the lake were selling for a $7,500 premium and that they were the only lots being sold (USEPA, 1995). The premium prices charged for lots with water amenities combined with the added marketing tool of a "natural" water feature can provide economic benefits for the developer. The most desirable and expensive lots - the one nearest to the water feature - sell first therefore allowing the developer to recoup some of the initial costs of the development. As many municipalities are requiring new developments to handle storm water runoff on site, the developers would be amiss if they did not take advantage of the opportunity to create and market a unique feature in the landscape. 8.2 Infrastructure Costs Another economically tangible benefit to the developer would be potentially lower costs of mstalling infrastructure (capital emplacement) such as earthworks excavation and lower materials costs (fewer and smaller pipes, manholes, drains). However these lower costs are offset by the higher costs of certain BMPs such as oil/grit separators and sediment traps which are expensive in both installation and maintenance costs. Economies of scale can also be realized when implementing numerous BMPs on a site (Brown, 1997):— Some of the cost savings can be passed on to the homeowners. The case study of China Lake in Maine found that a system of infiltration trenches and vegetated buffer strips to catch runoff from the roof of a house cost $750 to install rather than $800 for a conventional gutters and 51 downspouts. The infiltration trenches had the added environmental benefit of filtering phosphorus from the water that had been causing algal blooms in the lake (Feuka, 1995). The draft report prepared for the greater Vancouver Sewerage and Drainage District did prepare some cost benefit estimates that were gathered from various sources such as municipalities and government agencies (Dayton & Knight, et al., 1998). Cost benefit reviews for structural BMPs were done for a hypothetical 15-hectare residential development, a 0.5 ha municipal works yard and a 2 ha office complex. The selected BMPs were chosen for their suitability within a development type as well as for their capacity to handle the type and amounts of pollutants generated in a particular development. The cost benefit figures are meant only as a guide, not as firm dollar values. Comparisons to conventional storm water management costs would have to be done on a per-region basis to measure the infrastructure costs savings of BMPs. However, the environmental benefits of improved water quality, improved or retained wildlife habitat, recreational opportunities and aesthetic enjoyment cannot be given a dollar amount. These "intangible" benefits of storm water BMPs should also be considered when a full-cost accounting is done for an alternative storm water management plan. The economic costs of implementing BMPs may be higher, but the ancillary and intangible benefits may be well worth the added monetary costs. 8.3 Maintenance Costs Cost benefit figures were also completed for non-structured and operational BMPs (Dayton & Knight, et al., 1998). These were more difficult to quantify as limited information was available 52 with regard to the impact of public education programs, environmental studies, municipal bylaws and other legislation on the overall costs of a development. On-going maintenance of structural BMPs and the general "good housekeeping practices" of a community are an integral part of controlling and limiting the negative impacts of storm water runoff. A regular maintenance schedule is mandatory if the BMPs are to function as designed. For most of the structural BMPs listed, the maintenance costs seem to average between 3% and 6% of the BMP construction costs per year. For example, using the construction costs listed by Dayton & Knight (1998), the construction costs for a 100-m long grass swale would be $5,000 (100m X $50/linear m). Maintenance costs for the swale would be approximately 6% of the construction costs per year or $300. For the swale, maintenance would consist of mowing the grass surface, removal of debris and reseeding bald patches. Replacement costs of BMPs are also difficult to quantify as the total life spans of many BMPs have not been determined. For the conventional storm sewer system, estimates could be made as to the life expectancy of the infrastructure (pipes, drains). The typical life span of a conventional system is 75 years and capital emplacement and replacement costs can be amortized over that period of time (CMHC, 1997). Storm water BMPs have not been in existence for that length of time and cannot therefore be compared on that basis. 53 9.0 SOCIAL IMPACTS OF BMPs Storm water BMPs affect the human social environment as well as the natural environment. Functioning as a piece of "beautiful infrastracture", BMPs in the landscape can affect our quality of life in our communities while also serving us as a utility. i 9.1 Recreation When BMPs are integrated into the design and function of a community they may serve as the "backbone" of a recreational system of parks and greenways (Tourbier, 1994). Open space in communities would not only serve a recreational purpose but also be part of the storm water management system. When there is no rain or snow, these open spaces would serve as playfields for sports such as soccer, football and baseball. During a rain event, when sports activities are unlikely to occur, the fields may be flooded with excess runoff an allowed to infiltrate (Thayer, 1994). In the case study of the Village Homes at UC Davis, the sandy surfaced infiltration basins serve as sandboxes for the community's children when dry and let water soak into the ground after rain events (Thayer, 1994; Ferguson, 1998). To the children, the BMP is a fun part of the landscape. As well as being the open space 'backbone", some BMPs can provide passive recreational opportunities. Constructed wetlands can attract wildlife, particularly avian species, which in turn attracts people who may enjoy bird-watching and walking around the wetland. Permanently wet features such as man-made wetlands and wet retention ponds are a unique feature in the landscape and therefore attract people to them. Many wet ponds have paths 54 around them to encourage people to walk and cycle near the pond. The essential function of the ponds is forgotten when people use them for recreation. 9.2 Aesthetics and a Sense of Place The prevailing suburban aesthetic desires neat, well-maintained landscapes (Nassauer, 1995). The neatly mown front yard of many suburban homes is an indication to outsiders that the homeowner takes pride in his or her possessions and is a "good neighbor" (Nassauer, 1995). The well-kept home may also been seen as an indication of the homeowner's socioeconomic status and becomes a part of the entire neighbourhood's image. The neighbourhood's image to outsiders can be a powerful signal as to that community's prestige and even safety (Perks & Clark, 1996). This suburban aesthetic also impacts the public realm. Utilities are often hidden away underground or masked by vegetation or false building fronts. Overhead electrical wires and exposed drains are generally though of as "unattractive" and "ugly" to suburban residents. In order for a utility to be accepted into the prevailing suburban aesthetic, it must be see as "neat" and "well-maintained"; it must not look like a utility. Therefore storm water BMPs should be designed to "fit" into the community's image and any aesthetic guidelines developed for the community. The BMPs must blend into the community and almost become invisible - to just be seen as open space or a stand of trees and shrubs rather than STORM WATER MANAGEMENT. As stated in a previous section, the presence of some BMPs may be used as a marketing tool for developers to attract potential home buyers. Storm water BMPs can contribute to the aesthetic appeal of a community. When properly designed and maintained, some BMPs such as wet ponds and man-made wetlands can be marketed as "natural" feature of the site. The "natural" 55 feature would contribute to the image of the development being close to "nature" and be a positive selling point for the community. A series of wet ponds may distinguish a suburb from surrounding developments of the same type and may be marketed as "Cranston Lakes". The community's image would be linked to the ponds and would also be distinguished from other communities without ponds. The BMPs provide a "sense of place" for the community, a feature they can call their own and one that also provides them with environmental benefits whether they realize it or not. Storm water BMPs, while providing obvious environmental benefits, can also impact the social and economic spheres of our lives. The potential benefits of BMPs is huge, however the implementation of these alternative storm water management techniques requires careful design, construction and maintenance in order for that potential to be realized. 10.0 BMP TYPOLOGIES FOR CRANSTON After considering the site biophysical information and the design constraints already placed on the development as well as the "toolbox" of BMPs currently available, the most appropriate BMPs to use on the site were decided upon. These included dry swales, wet ponds, dry basins, infiltration trenches and vegetated filter strips (Dayton & Knight, et al., 1998). The next step in the process was to integrate the selected BMPs into the landscape without compromising their function and without compromising the aesthetic appearance of the suburb. In essence, the integration of the BMPs into the landscape sought to create a "beautiful infrastructure" - a utility that did not look like a conventional utility but would still function as 56 a utility (Sheppard, 1999). Storm water would be managed by the landscape rather than being a separate part of the landscape. In considering the integration of the BMPs into the site, it was also appropriate to consider the site's regional landscape context and ways to integrate the development back into this regional context. The integration of the BMPs into the community design could also serve to enhance the community's landscape link to the region. This gave rise to the development of the site's BMP landscape typologies. The typologies use the BMPs to emulate a particular landscape type. In the natural environment, these landscape types are distinct due to variations in vegetation, moisture regime and wildlife. The use of BMPs would then be used as the "backbone" of these landscape types to create open space within the community while also providing the function of a utility (Tourbier, 1994). The landscape types for this project were adapted from the regional landscape surrounding the site and have been grouped as the: • Prairie Grassland • Prairie "Pothole" or Wetland • Prairie Waterway or River Valley 10.1 Prairie Grassland Calgary is situated in the Mixed Prairie region which is characterized by "seasonal moisture and temperature extremes of a typical continental climate" (Bragg & Steuter, 1996). The 57 d o m i n a n t f o r m s of vegetat ion are perenn ia l grasses such as wheatgrass a n d needlegrass, a n d forbs a n d herbs such as pra i r ie crocus, sage a n d go lden rod ( N A M P , 1994). The grasses domina te w h e n mois tu re a n d solar cond i t ions are too extreme fo r other types of vegetat ion such as trees a n d shrubs. Mos t of the nat ive grassland areas w i t h i n the c i t y o f Ca lgary a n d s u r r o u n d i n g areas have been dest royed due to agr i cu l tu ra l c u l t i v a t i o n a n d u rban iza t ion . The largest piece of na t ive grassland r e m a i n i n g i n Ca lgary is i n Nose H i l l Park ( N A M P , 1994). A r o u n d the Crans ton site, there are st i l l some patches of na t ive grassland. These patches are f o u n d m a i n l y o n the steep slopes of the escarpment a n d w i t h i n ravines. H o w e v e r most o f the l a n d a r o u n d the site has been d i s tu rbed t h r o u g h h u m a n use such as agr icu l ture . 10.2 Prair ie " P o t h o l e " o r W e t l a n d I n a serniar id c l imate such as Calgary 's , the presence of wa te r is genera l ly l i m i t e d to r ivers, creeks, sma l l lakes a n d wet lands . These wet lands , also cal led "po tho les " due to thei r sma l l size, are also l i m i t e d i n n u m b e r i n their na tu ra l state due to the deve lopment a n d cu l t i va t i on of the Prairies. I n the Calgary reg ion, there are 2 m a i n types of wet lands : permanent a n d seasonal wet lands . The permanent we t lands have a p o o l o f s tand ing wate r w i t h i n t h e m yea r - round w h i l e the seasonal we t lands d o no t con ta in a permanent p o o l of wa te r a n d m a y be d r y fo r ex tended per iods of time t h r o u g h o u t the year. There are some sma l l we t lands just n o r t h o f the site (F igure 58 6), but normally the presence of wetlands within the city boundaries is rare outside of parks and protected areas (NAMP, 1994). Cattails, bulrushes, rushes and sedges are the dominant vegetation in the wetlands. Due to the presence of water, shrubs and trees may also grow in the area surrounding these wetlands. The variety of vegetation in the wetlands results in a diversity of wildlife (Appendix 2). These wetlands provide important wildlife habitat for waterfowl and nesting birds such as mallards, blue-winged teaL northern pintail and northern shoveler (Bart, 19%). Series of wetlands (or complexes) provide breeding and stopover points for wildlife (NAMP, 1994). 5 9 Figure 6 Vegetation and landscape types surrounding site Source: City of Calgary, Natural Area Management Plan, 1994 o 60 103 Prairie Waterway The 2 main rivers running through Calgary, the Bow River and the Elbow River, along with Nose Creek, create another distinct landscape type within the city. It is within these river valleys that trees and shrubs dorrtinate due to the abundance of water. The vegetation appears to be lusher compared to the surrounding grasslands and the darker green of the shrubs and trees delineate the watercourse. The most dominant trees in these river valleys are trembling aspen and balsam poplar. Other tree species include white spruce and Douglas-fir. Dorninant shrubs are saskatoon, chokecherry, dogwood and willow (Appendix 2). These three landscape types contribute to the image most people have in their minds when they think of the "Prairies" - tall grasses waving in the wind, few trees and shrubs except in the valleys of meandering rivers and beside small wetlands. This landscape, combined with the views of the Rocky Mountains to the east of the city provides a unique visual setting for the residents of Cranston. 61 11.0 CRANSTON SITE DESIGN When implementing the selected BMPs into the site layout design for Cranston, it became evident that the conventional suburban layout design of cul-de-sacs and dead-end street would not be the most efficient or effective layout to maximize the BMPs' function. In many suburban developments, a "tried-and-true" layout that emphasizes the efficient land use is overlaid onto the site, usually without consideration of the site's unique characteristics. The open space within the suburb is then designed and landscaped as any other park space in any suburb in North America, contributing to the visual conformity of the development with any other development of the same type. The Cranston site is fortunate in the fact that there is a distinct natural feature on the site - the north-south escarpment - that distinguishes the development from any other in the city. However, the layout of the site follows the conventional suburban pattern of development. 11.1 Alternative Site Layout Design The alternative site layout design for Cranston affects only the areas of public dedication such as streets and parks. The built form of the private housing lot has not been altered in this project, although to create an even more sustainable community the private lot must be addressed. 62 112 Zoning (Drawings (S3 & S4) The total number of lots in the alternative plan is 2,375 close to the conventional plan's 2,367. The alternative design is slightly denser due more lots being zoned RS-1 Small Lot (8.5m frontage). As more of the site is designated open space in the alternative plan, the same amount of lots is placed on a smaller amount of land. The net developable area in the alternative plan is 144.67 hectares compared to 151.22 hectares in the conventional plan. The amount of low-density and medium density housing (RM-2 and RM-5) is slightly increased, but on the whole the community is still single-family residential. 11.3 Open Space (Drawings S5 & S6) When considering storm water management, one should examine how and where water moves on the site. Analysis of the pre-development topography of the Cranston site showed that there were natural areas of water collection on the site that contributed to the formation of the large ravine on the escarpment. All water on the site wants to flow to the escarpment and the ravine in particular. The alternative site layout design for Cranston uses these natural areas of water collection by locating green open space in these areas. These park areas will collect the overflow runoff from the roadside swales and streets. Any water that reaches these green spaces will be held on the land until it infiltrates into the soil or evaporates. The park space also provides the community with recreational spaces and serves to connect the community with the larger regional landscape. 63 The alternative design calls for approximately 8 hectares more open space than the conventional plan (Appendix 3). The amount of land along the escarpment edge has been increased to preserve more of the unique character of the escarpment. As well, by moving the housing lots back from the edge, the visual impact of a row of houses along the edge may be reduced. The central open space has been condensed from the radial pattern of interblock local pathways into a large central open space between the two school sites. This "middle green" wil l be the main recreational hub of the community, second only to the escarpment edge. There are also two interblock greenways that connect to the escarpments and the regional pathway. Another small park is located in the northeast section of the site. The street and block layout of the alternative design have also changed in order to direct water to the green open space as well as to provide better connections for both automobiles and pedestrians within the community. The street layout attempts work with the natural flow of water on the site, rriamtaining water flow to the open green space in the areas of water collection. 11.4 Storm Water Management (Drawings S7, S8 & S12) Current storm water management techniques on the site utilize curbs and gutters, pipes and drains to collect and convey storm water away from the site to an outfall that drains into the Bow River. Concrete drainage gutters at the rear of lots collects runoff from the individual lots and transports it to the nearest street drain. 64 There are a variety of storm water best management practices employed in the alternative site design for Cranston. Reduction of impervious surfaces and disconnection of impervious surfaces are two- (2) non-structural BMPs used in the alternative plan. The structural BMPs used are dry swales with underdrains, wet ponds and vegetated filter strips. The surface layer of soil is classified to be loamy sand and is a well-drained soil so infiltration practices such as swales and filter strips is acceptable. This surface layer of topsoil is approximately 20 cm deep and overlays a layer of silty clay soils which are poorly drained. It is therefore important not to overwhelm the infiltration devices as they may only be efficient up to a certain level given the soils. The loamy sand soil can infiltrate 61.2mm of rain per hour while the silty clay subsoil can only infiltrate 1.5mm of rain per hour (Ferguson, 1998). In the alternative design, dry swales with underdrains line all of the streets in the community as well as the rear of lots on those blocks without back lanes. The underdrain system removes excess runoff from the underground infiltration trench to a secondary sewer system to prevent the soil surrounding the infiltration trench from becoming saturated. The trench must fill to capacity before the water reaches the underdrain therefore allowing the maximum amount of water to be stored and infiltrated into the ground. An outfall to the Bow River is still required, however the amount of water that drains from the outfall will be reduced and the water quality of the runoff improved. During the winter months, most infiltration surfaces are frozen. However small amounts of infiltration may still occur during the chinooks., when the weather warms and the top layer of soil may thaw enough to allow for some infiltration. Calgary usually does not have a huge spring thaw to handle as little snow accumulates over the winter due to the chinooks. 65 The roadside swales use the concrete driveways as check dams between swales. During periods of heavy rain, when a swale has reach its capacity, overflow water will flow across the driveway to the next swale. Inuring smaller rain events (typically less than 15 mm of rain), the swales do not reach their overflow capacity and water is therefore ponded in the swale and allowed to infiltrate. The permeability of the soils over the underground trench removes quickly removes water from the surface. The sheer length of the swales gives them tremendous holding capacity. In the alternative design, there is approximately 55,000m of swales. If a lOOmeter swale is 2 meters wide and 0.3 meters deep, it has a capacity of approximately 4 cubic meters. Therefore, on the site, swales can contain 2,200 cubic meters of water. Combined with the storage capacity of the underground trench of approximately 2 cubic meters per 100m length, the total volume of water stored in the dry swales is 3,300 cubic meters (Appendix 4). Therefore for the 2-year rain event, swales can handle over half the runoff amount that occurs in a 15 rninute duration storm (Appendix 1). Cuts in the driveway allow water to pass over the drive with minimum inconvenience to the homeowner. These cuts also allow for frozen water in the winter, particularly after a chinook has passed through the city. The cuts prevent ice build-up on the driveway while also creating an aesthetic pattern along the street. The small wet ponds in the alternative site layout design collect and detain storm water runoff for small drainage areas of the community. The water level in these ponds can fluctuate up to 0.5m above the permanent water level and are an average of 2 meters deep. An impermeable clay liner covers the bottom of the ponds to prevent infiltration from occurring. Loss of water 66 from the ponds should only be through evaporation into the atmosphere, evapotranspiration through plants and during periods of heavy rain, and an outlet pipe that connects to the secondary system. The green open space within the community also functions as part of the storm water management system. In periods of heavy rainfall, the swales will reach their capacity and overflow. As many of the streets in the alternative plan are designed to work with natural drainage patterns, the swales will overflow to the green space. Water will be collected in the green park space and held until it infiltrates. This is only expected to occur in 10-year and above rain event. In case of the 100-year event, water will collect in these green spaces and eventually be directed out to the escarpment edge. The alternative storm water management system relies on vegetated surfaces to collect, convey and treat storm water runoff. The implementation of this alternative plan requires careful site inventory and analysis in order to select the most suitable BMPs for the site and climate. 11.5 Streets (Drawings S9, SIO, Sll) Streets in Cranston fall into two categories: collector and residential. The street right-of-ways have not been altered from the conventional layout however, in the alternative plan, the streets in Cranston have been narrowed to reduce the amount of impervious surfaces in the community. The main collector is the ring road that runs around the community and uses the Prairie Waterway landscape typology to define its presence in the community. The placement of the 67 collector is the same as in the convention plan due to its efficiency of movement and collection. The collector has a center median that also contains a dry swale with underdrain to collect runoff from the street. Street trees line both sides of the collector and also the median, creating a unique space in the development due to the presence of the vegetation. Curb cuts at regular intervals in the curb allow runoff from the roads into the roadside swales while mamtaining the formal and neat appearance of a typical suburban main entrance road. The residential streets are where the most impact is made when reducing impervious surfaces. The conventional plan calls for a variety of street types from Collector, Boulevard Collector to Divided Residential and Residential. The paved lane in residential streets in the conventional plan is wide at 9.0m (approximately 27 feet). In he alternative plan, this paved width is reduced to 7.0m (approximately 21 feet). Therefore, while the total road length in the alternative plan is actually longer than the conventional plan, there is Jess impervious surface (Appendix 3). In the alternative plan, impervious surfaces have been reduced by 3.5% of the total site area, which translates into approximately 5 hectares of land. The residential streets in the alternative plan would look very similar to the streets in the conventional plan with the exception of the roadside dry swales. As well, there would be no curbs and gutters along the residential street. Runoff from the roads would flow directly into a grass filter strip before entering the swale itself. The back lanes of the alternative plan are also narrower than the conventional plan and are surfaced with crushed gravel rather than asphalt. The crushed gravel is pervious and would therefore allow water to penetrate the soil while still providing an adequate driving surface for cars and garbage trucks. 68 The alternative site layout design calls for a change in the suburban street profile as well as the suburban aesthetic. The above changes to the conventional suburban design are site-specific and do not take into consideration the current municipal engineering or zoning regulations of the city of Calgary. 12.0 OPEN SPACE DESIGN The design of the open space is where the BMPs and the landscape truly integrate. There are 4 major open spaces within the alternative site layout design: the Middle Green, the Prairie Pothole Park, the Southern Greenway and the Northern Greenway. As stated before, the location of these open spaces resulted from the site analysis to take advantage of the areas of natural water collection on the site. The open spaces are an integral part of the storm water management system of the alternative plan as they can collect and retain excess runoff from the roadside swales. The conceptual grading for the site seeks to direct water to the green open spaces so in a heavy rain event such as the 5 or 10-year storm, excess runoff would collect in the parks rather than in the streets and in house basements. The large areas of open land also serve to disconnect areas of imperviousness on the site. It is in these open spaces that the combination of storm water BMPs and landscape typologies come together. For example, the wet pond structural BMP is designed to emulate the Prairie "pothole" wetland, rather than simply being a water feature surrounded by mown grass. 69 The application of the landscape type to the BMP adds greater depth to the function of the BMP as well as greater aesthetic value to the community. In the above example of the wet pond as Prairie "pothole", wildlife habitat is added when the wet pond is landscaped and planted to emulate the natural feature. The wet pond then becomes an aesthetic feature in the community, providing recreational opportunities such as bird watching, for the residents. The BMP still functions as a utility - the water level in the ponds will fluctuate during and after rain events, but through the application of a landscape type, has become much more than a utility; it has become a piece of "beautiful infrastructure". The utility does not look like a conventional utility but its overall function has not been impaired. 12.1 The Middle Green (Drawings S14 & S15) This is the largest public open space in the community at approximately 6.0 hectares in area. The Middle Green is the teraiinus for many streets and will receive the excess runoff from the swales along those streets. The elevation of the park is such that it is lower than the surrounding houses to allow for water to collect in the park without flooding over into the adjacent homes. The dominant landscape type in the Middle Green is the Prairie Grassland. There are stands of native trees and shrubs on either end of the park to define the Middle Green from the two schoolyards and play fields. However, the majority of the park is to be planted with native mixed grass species to emulate the native, pre-development landscape and to serve as a visual link to the larger regional context of the site. This grassland meadow will also be 'hummocky" also to emulate the appearance of the pre-development landscape. These small hummocks pr hills within the park offer residents the opportunity to get a larger view of the park space and the community. This type of landscape is familiar to Calgary residents as the Nose Hill Park in 70 the northwest of the city is mostly native grassland prairie and there are patches of this landscape type in the Fish Creek Provincial Park, which is very close to the Cranston site. 122 The Prairie 'Pothole" Park (Drawings S16 & S17) This small park in the northeast corner of the site is unusual in the fact that it does not drain towards the Bow River. This site was a depression according to the pre-development topography and is close to some existing wetlands just north of the site. The presence of these existing wetlands and the topography made this location ideal for creating a wet pond. The wet ponds also serve as another link to the landscape outside the site. As stated before, the wet ponds are designed to emulate the natural landscape type of prairie "pothole" or wetlands. Planted with native wetland species and plants that favor wetter areas, these ponds will attract both people and wildlife while still functioning as part of the alternative storm water management system. A strip of mown grass around the street edge of the park serves as a "cue to care" (Nassauer, 1995). This neatly mown grass signals that the park is maintained and cared for by someone, in this case the municipality. Proper maintenance is vital so that the ponds will not become unsightly sloughs, full of mosquitoes and algae. 71 12.3 The Southern Greenway (Drawings S18 & S19) The Southern Greenway extends for almost the entire width of the site and terminates at the escarpment. For most of its length it is an interblock greenway, providing a link to the escarpment for adjacent houses and connecting neighbourhoods. Most of the greenway is native grassland meadow, similar to that found in the Middle Green. The terrain is slightly hummocky and trees and shrubs define the edges of the greenway sections when they intersect streets. The last section of the greenway, before it reaches the escarpment, contains four (4) small wet ponds, similar to those in the Prairie Pothole Park. This progression from grassland to wetland is similar to the natural landscape surrounding the site as water collects at the edge of the escarpment and is therefore wetter than the upland areas, able to support trees and shrubs. Similar to the Middle Green, the Southern Greenway will collect excess runoff from the roadside swales and detain that water until it infiltrates or evaporates. The elevation of the Greenway is also below that of the adjacent houses to prevent flooding during large rain events. The greenway connections to the escarpment are planted with the natural escarpment vegetation. This vegetation serves to link both physically and visually, the community with the escapement edge and regional pathway. 12.4 The Northern Greenway (Drawing S20) This greenway is similar to the Southern greenway with the omission of wet ponds. The greenway is a shorter interblock greenway that links the two parts of the northwestern neighborhood together while also providing a link to the escarpment. 72 13.0 INFRASTRUCTURE COSTS In this thesis, only the initial infrastructure costs were evaluated and compared. The up-front cost of installing a development's infrastructure is one of the largest costs borne by the developer. After installation of the infrastructure, it becomes the maintenance responsibility of the municipality. In making alternative storm water management economically feasible, the costs savings should be realized in the initial stages of infrastructure emplacement. Alternative storm water management techniques are often thought to be more expensive to install and there is less incentive from an economic standpoint to install these alternative measures when the conventional management techniques are more cost-effective and efficient. In evaluating the infrastructure costs of the alternative site layout design compared to the conventional plan, the gaps in information became very obvious. Storm water BMPs, due to their nature are very site specific. The construction costs for the same BMP on two different sites will often be very different. Construction costs are also typically regionally specific and add to the difficulty in cost comparisons. In comparing the alternative and conventional storm water management plans, a rough cost estimate was obtained from a construction source (Courtenay, 1999). It must be cautioned that the costs figures are for the use of this paper only as they are not adjusted for the Calgary region and are only a general cost guide. The cost estimate for storm sewer mains assumed a 1-meter diameter pipe, however some of the pipes in the Cranston conventional plan are larger. In order to normalize the numbers, the cost for the 1-meter pipe has been applied to the entire site. In the alternative plan, this 1-meter pipe 73 comprises the largest section of the secondary storm sewer system. The cost estimates for the dry swale with underdrain includes the cost of the underdrain pipe. When the total changes in infrastructure such as roads, sidewalks and storm water is calculated, the alternative plan achieves a $459,000 saving over the conventional plan (Appendix 5). This is due to the reduced amount of asphalt paving and curbs and gutters in the street profile. As well, the costs of implementing the dry swales and wet ponds are still less than installing conventional sewer mains. The costs of the storm sewer system have not been completely eliminated due to the presence of the underdrains and secondary system. However, if the secondary system were eliminated, there would be additional savings of almost $1 million in infrastructure costs. The wet ponds, due to their small size have smaller water storage capacity and therefore a lower cost than larger ponds. However there are economies of scale that are realized when one large pond is built rather than several small ones (Brown, 1997). Once again it must be emphasized that these figure are only estimates. On a per lot basis, the savings in infrastructure translates into a $193 saving per household unit. While this amount is not large, when considered along with the intangible aspects of BMPs: environmental benefits of cleaner water, retained ecological habitat and recreational and aesthetic enjoyment, the alternative storm water management plan definitely wins our over the conventional plan. However, when considering the property values of the alternative and conventional plan, the conventional plan is clearly the winner. The alternative plan has almost twice as many RS-1 74 Small lots than the conventional plan and half as many R-l lots. The R-l lots are the most expensive in real estate terms, so even though there are approximately the same number of lots in each plan, the conventional plan has more expensive lots and therefore increased property value. (Appendix 6). Rezoning the alternative plan to allow for more R-l zoning or redesigning the site layout to create another alternative plan may mitigate this property value effect. The design created for this thesis is only one proposal for the site; there could be countless designs that implement BMPs into the site. Additional savings may also be realized if small scale BMPs are installed on the private lots themselves. This may also reduce the amount of runoff from these lots, thereby reducing the amount of runoff that reaches the roadside swales and open space areas. 14.0 CONCLUSION Implementation of alternative storm water management techniques in a suburban context has the potential to realize economic savings as well as environmental benefits. As most suburban developments occur on "new" land - previously undeveloped and pervious, it is here that the effects of urbanization can be seen most clearly. It is also in these new developments that changes in storm water management are more easily integrated into the community. The BMPs could be installed along with other infrastructure such as sanitary sewers at the beginrung of site development. As shown above, there may even be cost savings associated with BMPs over the conventional system. Due to Cranston's proximity to the Bow River, any measures to protect the ecological integrity of this water feature must be examined. Storm water best management practices offer solutions 75 to help protect the water quality of the Bow River while serving as a piece of "beautiful infrastructure" on the site. The integration of the storm water management system into the landscape creates a unique community identity for the suburb and emulates natural hydrologic processes. The creation of BMP landscape typologies further integrates the BMPs into the larger regional context and also serves as a "backbone" for community open space (Tourbier,1994). As our cities and towns continue to grow into the next century, the use of storm water best management practices will become more widespread. Techniques will change and improve as more BMPs are installed and monitored. This alternative plan for Cranston only considers storm water management but there are other countless ways in which our developments could be made more sustainable. Storm water management is only the first step. 76 BIBLIOGRAPHY Argue, John R., 1994, A New Streetscape for Stormwater Management in Mediterranean-Climate Cities: The Concept Explored, Water, Science and Technology, vol. 30, no.l, pp. 23-32. Batt, Bruce D.J., 1996, Prairie Ecology - Prairie Wetlands, In Prairie Conservation: preserving North America's Most Endangered Ecosystem, F.B. Samson and F.L. Knopf (editors), Island Press: Washington, D.C. Bormann, Herbert F., Diana BalmorL Gordon T. Geballe, 1993, Redesigning the American Lawn: A Search for Environmental Harmony, New Haven: Yale University Press. Bragg, Thomas B. and Allen A. Steuter, 1996, Prairie Ecology - The Mixed Prairie, In Prairie Conservation: preserving North America's Most Endangered Ecosystem, F.B. Samson and F.L. 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Morrison, Bill, February 21,1999, Calgary River Valleys Committee, personal communication. Nassauer, Joan Iverson, 1995, Messy Ecosystems, Orderly Frames, Landscape Journal, vol. 14, no. 2, pp. 161-170. New York State Department of Environmental Conservation, 1992, Reducing the Impacts of Storm water Runoff From New Development. Perks, William T., and Andrea Wilton Clark, 19%, Consumer Receptivity to Sustainable Community Design, Calgary: Canada Mortgage and Housing Corporation. Scheaff er, John et al., 1982, Urban Storm Drainage Management, New York: Marcel Decker Inc. Schueler, Thomas R., 1987, Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban BMPs, Washington: Metropolitan Water Resources Planning Board. Sheppards, Stephen, 1999, Visual Resources Management lecture, Vancouver: University of British Columbia. Stanley Urban Land, 1998, Report Accompanying Outline Plan and Land Use Redesignation Applications: Cranston Phase 1, Calgary: Stanley Consulting Group Inc. Taylor, John D., 1992, Take Back the Water, Landscape Architecture, vol. 82, no. 5, pp. 50-55. Thayer, Robert L., 1991, Water Drives a Sustainable New Town, Landscape Architecture, vol. 81, no. 10, pp. 168. Thayer, Robert L., 1994, Gray World, Green Heart. Technology, Nature and the Sustainable Landscape, New York: John Wiley & Sons. Thompson, J. William, 1996, Let That Soak In, Landscape Architectufevol. 86. No. 11, pp. 60-67. Thompson, J. William, 1997, Clean Water Acts, Landscape Architecture vol. 87, no. 5, pp. 40-45. Tourbier, J.T., 1994, Open Space Through Stormwater Management: Helping to Structure Growth on the Urban Fringe, Journal of Soil and Water Conservation, vol. 49, no. 1, pp. 14-21. Trank, Andrea, 1992, Five Green Solutions, Landscape Architecture vol. 82, no. 1, pp. 50-53. 79 Urbonas, B. and Stahre, P., 1993, Stormwater Best Management Practices and Detention. U.S. Environmental Protection Agency, 1995, Economic Benefits of Runoff Controls, EPA 841-S-95-002, Washington: U.S. Environmental Protection Agency. Van Duin, B., Gareau, J., Jalkotzy, P., McAuley, J., 1995, Retention of an Existing Wetland for Stormwater Management: A New Approach for Calgary, Advances in Modeling the Management ofStormwater Impacts pp.239-254, Michigan: Ann Arbor Press. Zastrow, Jane B., 1998, Suburbia Future Tense, Urban Land vol. 57, no. 3, pp. 48-52. REFERENCE Internet Articles www.epa.gov Epp, Eduard, W. Perks, R. Perron, C. Sale, D. Van Vliet, 1999, Sustainable Community Design: Mackenzie Towne Case Study. Feuka, K. and Hanson, S., 1995, Best Management Practices: Cost-Effective Solutions to Protect Maine's Water Quality. 80 APPENDIX 1 RUNOFF VOLUMES TOTAL RAIN VOLUMES Formula: Intensity x Duration x Area x Runoff Co-efficient Area in ml Area: Total site: 151.22 ha 1,512,200 2 Year Storm - Site Intensity Duration Total Runoff VOLUME (mm/hr) (hours) Rain (m) Area (m2) Coefficient (m3) 5 min. s 61.5 0.08 0.0051 1,512,200 0.40 3,100.01 10 min. 46.1 0.17 0.0077 1,512,200 0.40 4,647.49 15 min. 38.0 0.25 0.0095 1,512,200 0.40 5,746.36 30 min 23.2 0.50 0.0116 1,512,200 0.40 7,016.61 1H 13.7 1.0 0.0137 1,512,200 0.40 8,286.86 2H 8.1 2.0 0.0162 1,512,200 0.40 9,799.06 6H 4.0 6.0 0.0240 1,512,200 0.40 14,517.12 12 H 2.6 12.0 0.0312 1,512,200 0.40 18,872.26 24 H 1.5 24.0 0.0360 1,512,200 0.40 21,775.68 5 Year Storm - Site Intensity Duration Total Runoff VOLUME (mm/hr) (hours) Rain (m) Area (m2) Coefficient (m3) 5 min. 110.1 0.08 0.0092 1,512,200 0.45 6,243.50 10 min. 82.5 0.17 0.0138 1,512,200 0.45 9,356.74 15 min. 66.4 0.25 0.0166 1,512,200 0.45 11,296.13 30 min 41.3 0.50 0.0207 1,512,200 0.45 14,052.12 1H 23.6 1.0 0.0236 1,512,200 0.45 16,059.56 2 H 12.7 2.0 0.0254 1,512,200 0.45 17,284.45 6H 4.5 6.0 0.0270 1,512,200 0.45 18,373.23 12 H 2.3 12.0 0.0276 1,512,200 0.45 18,781.52 24 H 1.1 24.0 0.0264 1,512,200 0.45 17,964.94 10 Year Storm - Site Intensity Duration Total Runoff VOLUME (mm/hr) (hours) Rain (m) Area (m2) Coefficient (m3) 5 min. 109.8 0.08 0.0092 1,512,200 0.50 — 6,918.32 10 min. 85.2 0.17 0.0142 1,512,200 0.50 10,736.62 15 min. 69.6 0.25 0.0174 1,512,200 0.50 13,156.14 30 min 42.7 0.50 0.0214 1,512,200 0.50 16,142.74 1H 23.6 1.0 0.0236 1,512,200 0.50 17,843.96 2H 13.1 2.0 0.0262 1,512,200 0.50 19,809.82 6H 5.9 6.0 0.0354 1,512,200 0.50 26,765.94 12 H 4.2 12.0 0.0504 1,512,200 0.50 38,107.44 24 H 2.5 24.0 0.0600 1,512,200 0.50 45,366.00 82 25 Year Storm - Site Intensity Duration Total Runoff V O L U M E (mm/hr) (hours) Rain (m) Area (m2) Coefficient (m3) 5 min. 134.2 0.08 0.0112 1,512,200 0.50 8,455.72 10 min. 104.8 0.17 0.0175 1,512,200 0.50 13,206.55 15 min. 85.5 0.25 0.0214 1,512,200 0.50 16,161.64 30 min 52.5 0.50 0.0263 1,512,200 0.50 19,847.63 I H 28.6 1.0 0.0286 1,512,200 0.50 21,624.46 2 H 15.7 2.0 0.0314 1,512,200 0.50 23,741.54 6 H 6.9 6.0 0.0414 1,512,200 0.50 31,302.54 12 H 5.0 12.0 0.0600 1,512,200 0.50 45,366.00 24 H 3.0 24.0 0.0720 1,512,200 0.50 54,439.20 LOO Year Storm - Site Intensity Duration Total Runoff VOLUME (mm/hr) (hours) Rain (m) Area (m.2) Coefficient (m3) 5 min. 170.1 0.08 0.0142 1,512,200 0.60 12,861.26 10 min. 133.8 0.17 0.0223 1,512,200 0.60 20,233.24 15 min. 109.0 0.25 0.0273 1,512,200 0.60 24,724.47 30 min 67.0 0.50 0.0335 1,512,200 0.60 30,395.22 I H 35.9 1.0 0.0359 1,512,200 0.60 32,572.79 2 H 19.4 2.0 0.0388 1,512,200 0.60 35,204.02 6 H 8.3 6.0 0.0498 1,512,200 0.60 45,184.54 12 H 6.2 12.0 0.0744 1,512,200 0.60 67,504.61 24 H 3.8 24.0 0.0912 1,512,200 0.60 82,747.58 Rainfall Amounts (24 hours) Average daily event: Average thunderstorm: 2 Year event: 5 Year event: 10-Year event: 100 Year event: Sources: Environment Canada 1999; City of Calgary, 1981 6.6mm 15mm -20mm 36mm 50.4mm 60mm 95.3mm 83 APPENDIX 2 VEGETATION and WILDLIFE SPECIES PLANT SPECIES Note: The following lists are by no means complete or comprehensive, but are meant to show the variety of vegetation and wildlife species that exist in the natural Prairie landscape. Balsam Poplar Douglas-fir Trembling Aspen White Spruce TREES Populus balsamifera Psudeotsuga menziesii Populus tremuloides Picea glauca SHRUBS Chokecherry Cotoneaster Dogwood Ground Juniper Manitoba Maple Mountain Ash Rose Saskatoon Shrubby Cinquefoil Water Birch Willow Wolfwillow Prunus virginiana Cotoneaster acutifolia Comus stolonifera Juniperus communis Acernegundo Sorbus aucuparia Rosa acicularis Amelanchier aim'folia Potentilla fruticosa Betuala occidentalis Salixspp. Elaeagnus commutata GRASSES Blue Grama Blue Grass Canada Thistle Goldenrod Green needle grass Kentucky blue grass Needle grass Northern Bedstraw Rough fescue Smooth Aster Western wheat grass Wheat grass Yellow Clover Bouteloua gracilis Poa spp. Cirsium arvense Solidago spathulata Stipa viridula Poa pratensis Stipa comata Galium boreate Festuca scabrella Aster laevis Agropyron smithii Agropyron trachycaulum Trifolium aureum xs AQUATIC PLANTS Cattails Typha latifolia Beaked Sedge Carex rostrata Muskweed Chara vulgaris Sedge Carex spp. ANIMAL SPECIES BIRDS Canada Goose Common goldeneye Common Merganser Swainson's Hawk Red-tailed Hawk Common Merganser Spotted Sandpiper Common Snipe Tree Swallow House Wren Cedar Waxwing Warblin Vireo Northern Oriole Black-capped Chickadee MAMMALS Beaver Black-tailed Prairie Dog Meadow Vole Moose Gray squirrel Elk Mule Deer White-tailed Deer Woodchuck Plains Harvest Mouse APPENDIX 3 CONVENTIONAL AND ALTERNATIVE PLAN COMPARISONS 31 ROAD DIMENSIONS - Conventional Site Layout ROW. Width Pavement Pavement Area Road Classification (m) Width (m) Lehgth (m) ( » 2 ) ROW Area ( m 2 ) Major 36.0 14.8 36 533 1,296 Primary Collector 27.0 14.0 1,233 17,262 33,291 Collector 21.0 11.5 1,971 22,667 41,391 Collector 23.5 11.5 140 1,610 3,290 Grand Boulevard 30.0 14.0 180 2,520 5,400 Divided Residential 23.0 14.0 1,574 22,036 36,202 Residential 15.0 9.0 11,680 105,120 175,200 Back Lane 10.0 10.0 180 1,800 1,800 Back Lane 8.0 8.0 5,289 42,312 42,312 TOTALS 16,994 173,547 340,182 34.02 ha Driveways to Street 1816 lots with front drives (R-l, Rl-A DC(Rl-A)) 908 with sidewalks 6m x 3m 16,344 908 without sidewalks 6m xl.5m 8,172 24,516 TOTAL ROAD AND DRIVEWAY PAVEMENT 198,063 19.8 ha 88 ROAD DIMENSIONS - Alternative Site Layout Road Classification ROW. Width (m) Pavement Width (m) Length (m) Pavement Area («>2) ROW Area (m2) Major 36.0 14.8 36 533 1,296 Boulevard Collector 27.0 13.0 2,235 29,055 60,345 Collector 21.0 9.0 915 8,235 19,215 Residential Streets 1 15.0 7.0 14,862 104,034 222,930 Back Lane 6.0 4.0 5,241 0 31,446 TOTALS 23,289 141,857 335,232 14.1 ha 33.5 ha Driveways to Street 1398 lots with front drives ( R-l, Rl-A, DC(Rl-A)) 1398 with sidewalks 3m x 1.5m 6,291 TOTAL ROAD AND DRIVEWAY PAVEMENT 6,291 148,148 14.8 ha Back lane surface in alternative plan is crushed gravel rather than asphalt, therefore the pavement type is pervious. Road pavement widths are narrower than the conventional plan. Road length is longer than the conventional plan due to the more connected street layout with fewer cul-de-sacs. Driveways to street are narrower than the conventional plan (3.0m compared to 6.0m). The sidewalk pavement has been counted as a separate number, therefore only that part of the street ROW (right-of-way) that is NOT sidewalk was included in the equation. 89 SIDEWALKS Length (m) Width (m) Area(m2) Conventional Plan 20,331 1.5 30,497 Alternative Plan 34,194 1.5 51,291 Alternative Plan: Approximately 75% more sidewalks than the conventional plan due to sidewalks on both sides of all streets within the community. Sidewalks on both sides of the street combined with the more connected site layout should encourage pedestrians within the community. Conventional plan typically only has a sidewalk along one side of most roads. 90 IMPERVIOUS SURFACES Housing - Conventional Plan 'Amount of Frontage (m) Average Lot DepuV (m) Area (m2) % • Impervious (Max: Lot Coverage) 'Impervious Area <m2) R-l - Single Family Res. 10,256 36.0 369,216 45% 166,147 Rl-A - 3,967 33.0 130,911 45% 58,910 DC(Rl-A) 6,912 33.0 228,096 45% 102,643 RS-1 - Small Lot 3,142 30.0 94,260 60% 56,556 R2-A Townhouses 676 33.0 22,308 45% 10,039 RM-5 Med. Density 30,500 60% 18,300 TOTAL Houses 24,953 875,291 412,595 41.2 ha Length (m) Pavement Area (m2) Impervious Area Roads - Conventional Plan 16,994 173,547 173,547 Driveways 24,516 24,516 198,063 Length (m) Width (m) Impervious Area (m2) Sidewalks - Conventional 20,331 1.5 30,497 Building Surface Area (m2) Parking Lot Area::: (m2) Impervious Area (m2) Schools - Conventional 4,536 765 5301 .53 ha TOTAL IMPERVIOUS AREA (m2): 646,455 64.6 ha As a % of total site area (m2): Total site 1,533,200 Housing 412,595 26.9% Roads 198,063 12.9% Sidewalks 30,497 2.0% Schools 5,301 0.3% TOTAL IMPERVIOUSNESS 646,456 42.2% +5% for walkways and greenways 44.3% 91 IMPERVIOUS SURFACES Amount of Frontage Average Lot Depth i.v.'-.-v. ••  ATf*a ( % Impervious (Max. Impervious Area Alternative Plan (m) <m) :• • SM :•).-.- r\ixzci yiii^j •  .v. Lot Coverage) (m2) Houses R-l - Single Family Res. 4,801 36.0 172,836 45% 77,776.2 Rl-A- 7,049 33.0 232,617 45% 104,677.7 DC(Rl-A) 3,889 33.0 128,337 45% 57,751.7 RS-1 - Small Lot 6,771 30.0 203,130 60% 121,878.0 R2-A Townhouses 636 33.0 20,988 45% 9,444.6 RM-5 Med. Density 31,400 60% 18,840.0 TOTAL 23,146 789,308 390^ 68.1 39.04 ha Length (m) Pavement Area (m2) Impervious Area fm2) Roads - Alternative Plan 23,289 141,857 141,857 Driveways 6,291 148,148 14.8 ha Length (m) Width (m) Impervious Area (m2) Sidewalks - Alternative 34,194 1.5 51,291 Budding Surface Area Parking Lot Area ; Impervious; Area;" (m2) (m2) (m2) Schools - Alternative 4,536 765 5,301 .53 ha TOTAL IMPERVIOUS AREA (m2): 595,108 59.5 ha As a % of total site area (m2): Total Site 1,533,200 Housing 390,368 25.5% Roads 148,148 9.7% Sidewalks 51,291 3.3% Schools 5,301 0.3% TOTAL IMPERVOUSNESS 595,108 38.8% +5% for walkways and greenways 40.8% COMPARISON Conventional Plan 44.30% 646,456 Alterntaive Plan 40.80% 595,108 Percentage Difference 3.50% 51,348 5.1 ha Alternative Plan has 5.1 hectares less impervious surfaces: due to narrower road, gravel back lanes. 92 OPEN SPACE Conventional Plan Area (m2) % of Total Site Area Environmental Reserve 21,000 1.4% Schools 88,900 5.8% PE Zoning 88,600 5.8% TOTAL 198,500 12.9% Alternative Plan / Area (m2) % of Total Site Area Environmental Reserve 86,500 5.6% Schools 88,900 5.8% PE Zoning 100,000 6.5% TOTAL 275,400 18.0% Total Site Area (m2) 1,533,200 Increased open space in the alternative plan is due to the larger amount of the escarpment edge dedicated to the environmental reserve. Open space has also been condensed to the large central green space between the two schools. Linear inter-block greenways serve as community connections and recreational space. 93 APPENDIX 4 SWALE CAPACITIES Swale Capacity The average roadside swale in the alternative plan has the following dimensions: Width: 20 meters Depth 0.3 meters Cross-sectional area of a swale: 2/3 WD Cross sectional area = 0.4062 m 2 Average length of swale = 100m Capacity of swale = 4.062 m 3 Underground Trench Dimensions: Width: 1.0 meters Depth (before water reaches underdrain): 0.5 meters Void space of aggregate: 0.4 Cross sectional area = WDV Cross sectional area = 0.2m2 Average length of trench = 100 m Capacity of trench = 2.0m3 9 5 APPENDIX 5 INFRASTRUCTURE COSTS COSTS - C O N V E N T I O N A L A L T E R N A T I V E Roads Curb & Gutter - poured in place $30/linear m Asphalt Paving - $4.65/square m $691,500 $806,994 $191,160 $659,635 T O T A L $1,498,494 $850,795 Storm Sewer Mains Total costs of Installation of 1.0m main $300/ m Catchbasins $3,478,500 $955,800 T O T A L $3,478,500 $955,800 Swales Swale w i th 4 inch/lOOmm pipe $26/linear m Check dams - $75 per dam $0 $1,430,546 $98,369 T O T A L $0 $1,528,915 Wet Ponds Excavation $12/cubic meter Installation Costs $50/cubic meter of water storage $0 $228,732 $953,050 T O T A L $0 $1,181,782 T O T A L S $4,976,994 $4,517,292 97 COST FIGURES Poured in place curbs & gutters: $30/linear meter: Conventional Plan length of road 11,595 m (total length - back lane length) Alternative Plan length of road 3,186 m (only along major roads) Asphalt paving: $4.65/ square meter Conventional Plan Pavement Area 173,547 m 2 Alternative Plan Pavement Area 141,857 m 2 Storm Sewer Mains: $300/meterforal.0mpipe Conventional Plan Length of roads 11,595 m (total length - back lane length) Alternative Plan Major roads 3,186 m E>ry Swales with Underdrains: $26/linear meter Conventional Plan No swales Alternative Plan Major road length x 3 (2 road side swales; 1 center swale) 9,558 m Residential Streets x 2 (2 roadside swales) 29,724 m Rear lot Drainage (behind R-l, Rl-A and DC(Rl-A) zoning 15,739 m Check dams: $75/per dam Conventional Plan 0 Alternative Plan Used in rear lot drainage channel; average distance between dams 12.0m 15,739/ 12.0 Wet ponds: $12/ cubic meter excavation $50/cubuc meter of water storage Conventional Plan 0 Alternative Plan Total volume of all ponds (6 ponds in total) = 19,061m3 APPENDIX 6 REAL ESTATE VALUES REAL ESTATE VALUES Average price for R-l zoned house: $175,000 Average price for Rl-A zoned house: $150,000 Average price for RS-1 zoned house $120,000 CONVENTIONAL R-l Lots 801 $140,175,000 Rl-A Lots 370 $55,500,000 DC(Rl-A) Lots 645 $96,750,000 RS-1 Lots 369 $44,280,000 Total $336,705,000 ALTERNATIVE R-l Lots 377 $65,975,000 Rl-A Lots 658 $98,700,000 DC(Rl-A) Lots 363 $54,450,000 RS-1 Lots 796 $95,520,000 Total $314,645,000 Difference $22,060,000 Alternative plan has lost over $22 million in real estate value. 100 APPENDIX 7 DRAWINGS l o I p CQ 5 I D T I OS I I D i2 Iu5 • • m i i _._L._.L. T i — 1 1 1 T.—n .1—n -< < V 2 R 2 < I Lu i l l l l r Si s u t3 I * M i l III I 1 I If 111 3 o co C o c > c o U H PQ W C4 H cn _) < H 2 w D En w 82 • 3 o >-. co cu . > .*-> CO C T 3 CU cn O P M o H W w PS H CO ,-) < z w Q on w PS * 1 1] is 111 112-115. to ! 1; 2 : i l 0 H % I Li 1 U w 01 2 1 / .«,| os o i i l l ta ? * , : i jp I P -Q ft-D - -% i ten < < U z 5 m 2 < 1 1 I I 6 a i U i u I I" / 1 2 0 1 2- I 

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