CHAPTER ONE

INTRODUCTION AND METHODOLOGY

THE DESIGN OF URBAN OPEN SPACE SYSTEMS FOR STORMWATER MANAGEMENT

Urban open spaces along stream corridor, and associated wetlands have the potential to fulfill multiple purposes. The use of these areas for SWM and recreation are primarily explored in this study. Two case study communities are used to illustrate how innovative urban open space networks may be planned and designed by preserving or creating open drainage systems. The two case study sites are Bellevue Washington and Albertslund Denmark within the Store Yejlea Yalley. As stormwater management {SWM) facilities, the primary concern for the use of both open space systems was to control water quantity. In light of emerging concerns for non-point source pollution in urban runoff, specifically in the case of Bellevue, Washington, greater emphasis is now being placed upon stormwater quality. Through a review of the current literature this study discusses the benefits of using natural and low structural elements such as streams, lakes, and wetlands for stormwater quality management. This study observes and explores how the two communities have (or have not) taken advantage of these elements for multi purpose open spaces.

Methodology

Intent

The intent of this study is to explore and gain an underatanding of the use of urban open space systems as used in the two study sites for the purposes of stormwater management and recreation. A basic premise of this work is that multiple uses of urban open space can and should be pursued. Through a literature search the means in which urban open space may accommodate multiple purposes, most specifically that of stormwater management, are discussed. Through the observation of two cases the extent to which these techniques are being applied is explored.

Study Process

The study process first included a literature search to gain knowledge in the areas of:

1. Urban open space - its values, history and what has traditionally shaped it, and when natural determinants have played a role in its formation.

2. Stormwater management - its traditional and state-of-the-art practices using low and non structural approaches.

3. The use of wetlands and streams for urban runoff water quality control.

During the literature search a set of general concepts and design criteria were found which address (1) the development of naturally determined urban open space systems and (2) the means in which natural, low, and nonstructural elements may be used for stormwater management. These concepts, listed below, and the design criteria listed in Chapter Three were used to guide the case study analyses and to find how or whether they have been applied.

1. Natural drainage ways and wetlands within and urban setting have been preserved primarily because they are least favorable to develop. This situation has resulted in the incidental preservation of wildlife habitat, informal recreation areas and the potential use of these areas for swm.

2. Drainage ways and low structural areas built to accommodate stormwater have the potential to to be designed for additional purposes such as parks and wildlife habitat.

3. The use of wetlands has not traditionally been a primary component in open space planning or in storm water management; yet, if properly managed, may be employed for these multiple purposes.

The Case Study Selections

The case study selections are the City of Bellevue in the State of Washington and the community of Albertslund, Denmark within the Store Yejlea Yalley. The case study sites were selected because that these sites maintain a network of open space which incorporate stormwater management facilities and because of their availability. Bellevue was chosen because it is nationally recognized as a leading example in implementing a successful and innovative stormwater management approach primarily using open natural systems. As well, Bellevue is close to the University of Washington and was therefore accessible for direct observation. The second study area, the Store Yejlea Yalley, Denmark, is an example within the greater Copenhagen region where the open space system was designed to incorporate both recreation and stormwater management for four adjoining communities while preserving and, in some instances, creating open water channels and lakes. Denmark was chosen due to the availability of the Valle Scholarship which funds graduate study in the Scandinavian Countries. The Country of Denmark has a rich design tradition and the opportunity to draw from another country's perspective in open space planning and stormwater management was seen as a positive addition to the study.

Initially a third case site was to be used in this study; South Richmond on Staten lsland in the City of New York where the preservation of the island's wetlands and stream corridors for stormwater management and a public trail network is being considered. A summer internship with the Department of City Planning on Staten lsland gave the author the opportunity to explore the open space plan for this area. Because this network is far from being physically realized (during the summer of 1988), this site was eliminated.

The Data Collection

The data collected were physical descriptions of how the study communities planned and designed for urban open space and stormwater management using natural process and sytems. The data was collected through the use of written material describing systems and through personal interviews with community planners and water management engineers (a list of contacts for both case studies are in Appendix D). The cases are not intended to be compared directly to each other but rather to be used as sources and means of gaining more direct knowledge as to how principles of designing for open space and stormwater management have been and may be applied.

Organization of the Thesis

An overview of the topics of open space planning, stormwater management, and the use of natural processes, most specifically that of wetlands, for the improvement of water quality are discussed in Chapters Two, Three, and Four respectively. Chapter Five describes the case study examples in two separate sections, presenting background material and the extent and use of structural and nonstructural and natural systems. Chapter Six, the analysis and conclusion, draws from the previous chapters, reviewing the general concepts formed earlier and giving possible design implications as to how the case study communities have or could combine stormwater management and recreation areas in urban open space planning.

The following outline was used to guide the observations and data collection for each of the case studies.

Case Study Outline

1. Why this community

A. who instigated O.S./stormwater plan?

B. when?

11. Description of Community

A. Physical

1. Location maps

2. Size; population; recent growth

3. Climate: rainfall

4. Topography

5. Drainage system locations

B. Political - Governmental bodies in charge

1. departments

a. who does open space planning

b. who covers stormwater management

c. who covers wetland protection

2. consultants

111. Description of Open Space Plan and Stormwater system

A. Major Goals and components of Open Space Plan

B. Major Goals and components of SWM Plan

1. Regulations

2. Low structural and natura1 elements

3. Studies

C. Actual plan (maps; photos)

IV. Analysis/Discussion

A. Use of wetlands and other natural features within open space/stormwater plans

1. for what purpose??

2. how designed for

a. flood control

b. water quality improvement

3. how effective

B. Design tools used

1. detention basins/ponds

2. catch basins

3. swales

4. wetlands? etc.

C. Possible inferences/suggestions/improvements