Principles for Ecological Landscape Design in Brownfield Business Parks

Transcription

1 Principles for Ecological Landscape Design in Brownfield Business Parks Part of USDA Forest Service research project # 00-JV : Aligning Social and Ecological Drivers of Urban Landscape Change School of Natural Resources & Environment, University of Michigan Note: All images that appear in this document are computer imaging simulations by A Chiesa. USDA FS Project 00-JV Principles for #Ecological Landscape Design in Brownfield Business Parks

2 These principles draw from research in landscape perception, landscape ecology, wildlife biology, toxicology, remediation techologies, and industrial ecology (Nassauer, Chiesa, and Corry, [2002] Submitted). They also draw from knowledge gained from focus groups conducted with business leaders in the Calumet Region, City of Chicago professional staff of the Departments of Planning and Development and the Department of Environment; landscape architecture, architecture, and engineering consultants to the City of Chicago; discussions with community leaders in the Calumet area, and brownfield remediation professional staff working in the Calumet area. They are illustrated by digital imaging simulations that will be included in a web-based survey of business decisionmakers, urban citizens, and environmental group members in Chicago and nationally. Results from the survey will be reported in None of the three principles described below can be successfully employed in isolation from the others. In brownfield redevelopment, the three principles should be employed together to achieve both new development that will be both ecologically sustainable and culturally sustainable over time, even when those who have participated in planning and redeveloping brownfield sites are no longer involved. 1

3 Principle 1: CONNECTION Brownfield redevelopment designs should connect flows of clean water, healthy habitats, and useable industrial by-products of energy and materials. This principle draws from landscape ecological knowledge of flows across the landscape, both within brownfield sites and across brownfield sites to and from the larger landscape context. In general, landscape ecology suggests that large, heterogeneous habitat patches and corridors, and redundant networks of habitat connections support healthier, more biologically diverse plant and animal populations by facilitating the movement of species. This principle also draws from the industrial ecology concept of co-location, which suggests that industries that are located near each other can exchange material and energy by-products to reduce waste and pollution and improve efficiency. 2

4 Principle 1: CONNECTION Corollary 1.1. LARGE HABITAT PATCHES Brownfield redevelopment designs should create large habitat patches on clean areas, especially where these clean areas are connected or near off-site habitat patches or corridors, including streams, wetlands, woodlands, or other indigenous ecosystems. Figure 1. This large habitat patch is located to expand on existing habitats adjacent to the brownfield sites. It has been constructed on clean soils, and separated from possibly contaminated groundwater by a perched water table. Formerly contaminated soils occur in the area of mown turf to the right. This principle requires examining the landscape context of the brownfield site to identify larger regional habitat patches and corridors and to identify adjacent patches or corridors that may be locally important. Where soil and water have not been contaminated, habitat patches can be created. New habitat patches are particularly desirable where they would enlarge or connect existing habitats. However, where connecting to or creating large habitat patches could bring wildlife in contact with water or plants that contain contaminants, the precautionary principle (see Principle 2) would suggest erring on the side of creating less habitat to discourage wildlife from using possibly contaminated areas as habitat rather than risking uptake of contaminants by wildlife or the transport of contaminants by plants or animals. 3

5 Principle 1: CONNECTION Corollary 1.2. WIDE, REDUNDANT HABITAT CORRIDORS Brownfield redevelopment designs should create connecting habitat corridors on clean areas, especially where they can broaden existing corridors (for example providing buffers for streams and expanding riparian habitats) or where they can connect nearby habitat patches, including wetlands, woodlands, or other indigenous ecosystems. Figure 2. This streambank is regraded to create a more shallow slope, and soil bioengineering establishes indigenous vegetation where the soil is clean, connecting to upstream and downstream habitats. This principle requires examining the landscape context of the brownfield site to identify larger regional habitat patches and corridors and to identify adjacent patches or corridors that may be locally important. Where soils and water have not been contaminated, wide, connecting corridors can be designed. Multiple connecting corridors that provide redundant species pathways are desirable. Where connecting habitat patches or corridors could bring wildlife in contact with water or plants that contain contaminants, maintaining separation will reduce the risk of transport of contaminants by wildlife (see Principle 2). For example, where creating a stream buffer could capture sediment and surface pollutants before they enter a stream, but wildlife use is not desirable because of possible exposure to contaminants, either structural solutions or soil bioengineering solutions that do not attract wildlife should be used. Soil bioengineering solutions that do not attract wildlife would select plants that do not provide cover, nesting, perching, or food for wildlife. 4

6 Principle 1: CONNECTION Corollary 1.3. CO-LOCATION OF INDUSTRIES Brownfield redevelopment designs should create opportunities for industries to exchange materials and energy by infrastructure designs that allow for industries that could exchange materials or energy to be clustered together. Figure 3. The concentration of industries in the buildings shown could allow waste energy or material by-products of one industry to be used by other industries located nearby. While this design doesn't facilitate flows of species within the riparian corridor, it does prevent pollution by facilitating flows of industrial by-products. If soils or groundwater near the stream retain possible contamination, discouraging flows between the riparian area and the stream may be the most ecologically beneficial design (see Principle 2). This important idea from industrial ecology prevents pollution and reduces demand for reused energy or materials. It also encourages industries that exchange materials and energy and minimize transportation costs to be clustered in a concentrated area. 5

7 Principle 2: SEPARATION Brownfield redevelopment designs should separate flows of possibly contaminated water, sediment, and plants from flows of clean water, sediment, and plants. Landscape ecology suggests that landscape pattern affects flows across the landscape, both within brownfield sites and across brownfield sites to the larger landscape context. Based on this idea, Principle 2 employs the precautionary principle of ecological design. It assumes that brownfield remediation that is intended to limit human risks from exposure to toxic substances will not eliminate risks to wildlife and risks to humans, and that formerly contaminated areas that have been remediated can pose potential long-term risks for humans and wildlife. Wildlife, wind, or water could spread remaining contaminants to the surrounding landscape. Principle 2 also assumes that some phytoremediation areas that are used by wildlife could pose risks for wildlife health and the larger landscape. Employing landscape ecology, this principle directs planning and design attention to protect the landscapes surrounding brownfield sites from flows of remaining contaminants. At the same time, Principle 2 assumes that brownfield redevelopment presents some excellent opportunities for creating habitat, cleaning and detaining storm water, and enhancing community and business landscape amenities (see Principle 1). It shows how flows of water and species can be designed to reduce risk of people, pets, and wildlife, and to discourage flows of contaminants to the larger landscape. 6

8 Principle 2: SEPARATION Corollary 2.1. CLEAN STORM WATER AND CONTAMINATED GROUND WATER Brownfield redevelopment designs should detain storm water on the surface in areas where it could infiltrate to contact possibly contaminated groundwater. Figure 4. The impervious paving of this parking lot could be located on possibly contaminated soils. The rainwater garden detention islands in the parking lot are designed with below-grade barriers to separate storm water from contact with possibly contaminated soils and ground water. This approach to storm water management is intended to keep storm water clean after it falls on roof tops or clean areas of business parks. Paving, rooftops, or a below-grade barrier that creates a perched water table can separate storm water from ground water. Surface detention also encourages evapotranspiration back to the atmosphere and movement to local streams or wetlands. Roof run-off may be cleaner than surface water run-off from roads and parking lots, so a three-tier system of storm water detention (roofs, roads, and ground water) that directs roof run-off to habitat areas but keeps road run-off separate from possibly contaminated ground water may be ideal. 7

9 Principle 2: SEPARATION Corollary 2.2. PAVING, TURF, AND HABITAT Both paving and mown turf discourage wildlife from using an area as habitat. In areas where contamination may remain, paving or turf may be the most ecologically beneficial landcover. Figure 5. While this area has been remediated for commercial and industrial uses, shallow -rooted turf and paving discourage movement of remaining contaminants to the surface. Carefully choose plants to discourage wildlife in areas that could continue to have low levels of contamination. Avoid toxic effects on wildlife or pets and animals becoming vectors for contaminants. Non-turf vegetation that could attract wildlife may not be appropriate for areas that contain even low levels of contamination; impervious surfaces (parking or buildings sealed from contaminants) may be more suitable for such areas. In addition, mown turf or impervious surfaces can be used to separate "clean" larger habitats from less clean areas and discourage movement of wildlife into low level contamination areas (see Corollaries 1.1 and 1.2). Concentrations of buildings and paved surfaces that are often needed for co-location or for large manufacturing industries may be appropriately located where contaminants must be sealed below ground. For low level contamination areas, impervious surfaces of paving and buildings may be more appropriate choices than natural-looking patches, which can attract people, pets, and wildlife (see Corollary 1.3). 8

10 Principle 2: SEPARATION Corollary 2.3. EXOTIC PLANTS AND HABITAT Where flowering plants, trees, and shrubs are located where contamination could remain, use exotic rather than indigenous plants. Exotic plants that do not provide food or cover for wildlife are most appropriate. Use indigenous plants only where soil contains no contaminants. Figure 6. This storm water detention area is designed to discourage wildlife use by the steep pond edge that discourages indigenous aquatic emergent vegetation. While some non-native, or exotic, plants provide wildlife habitat, some provide little food or cover. These plants may be very appropriate for brownfield redevelopment because they are often widely perceived as amenities and enhance the public image of a business park without attracting wildlife. 9

11 Principle 2: SEPARATION Corollary 2.4. NATIVE PLANTS AND HABITAT Brownfield redevelopment designs should anticipate that areas of native plants may invite human, pet, and wildlife use even if that use is not intended by the design. Design should discourage unintended use of areas that look natural, including phytoremediation areas, rainwater gardens, or habitat patches and corridors. Figure 7. Fences or other design cues should be used around natural-looking habitat to prevent unintended use by people and pets. The fence on the far left side surrounds this large habitat patch, preventing disturbance and defining the garden's edge. In order to protect wildlife in large habitat patches that are clean, design cues may be employed to discourage entry by humans or pets. While fencing can be used, more subtle cues also are useful. They include separating large patch habitat from neighborhoods or other human use areas by streams or wetlands, or by roads. Design should actively discourage entry by humans, pets, or wildlife into remediated areas where some contamination remains. For humans and pets, fencing may help prevent entry where possible low level contamination remains and that also may look like nature. Areas where contamination remains may pose less risk to wildlife if they are designed to 1) be distant and disconnected from clean habitat patches, 2) as very small patches, and 3) without combinations of shallow surface water and plants that could be used for cover, nesting, or food. In addition, to help discourage specialist species from using large patches where contamination remains, these should be fragmented into smaller patches and designed to maximize edge. 10

12 Principle 2: SEPARATION Corollary 2.5. REMEDIATION AND HABITAT Design phytoremediation areas to discourage their perception or use as natural areas or wildlife habitat, and to discourage wildlife, pets, or humans from coming in contact with phytoremediation plants. While the plants and wetland ecosystems that contribute to phytoremediation strategies can look like nature - to people and to wildlife, phytoremediation is intended to take soil and water contaminants into plant parts. Design for phytoremediation should be cautious to discourage contact and possible bioaccumulation of these contaminants in plant and animal tissues. In addition, design should discourage contact in order to prevent wildlife or pets from being vectors for possibly contaminated plant parts that they might eat or carry on their bodies to other parts of the landscape. 11

13 Principle 3. AMENITY Brownfield business park redevelopment designs should create amenity landscapes for businesses and nearby neighborhoods. Their maintenance should be obvious to neighbors and others who visit the site, understandable to maintenance staff, and cost effective for the business. These amenities should be both ecologically and culturally sustainable: beneficial to ecological health and immediately attractive to those who see the landscape. Regular care of the landscape should be immediately apparent to visitors and employees in the business park. Building facades, entries, and signs identifying businesses should be clearly visible from roads and parking lots. In addition, to complement Principle 2, amenities should be designed to: Discourage perception of possibly contaminated areas as natural landscapes, Encourage perception that possibly contaminated areas should not be entered, and Discourage informal recreational use where contamination remains. 12

14 Figure 8. The design and maintenance of habitat and non-habitat patches should make the amenity value of the landscape immediately apparent. This building facade and entry are framed with mown turf over half the area. Habitat patches include flowering plants and crisp, clearly defined edges. Figure 9. The unpaved area here is entirely indigenous plants. Making one-half of the unpaved area mown turf would demonstrate good care. Corollary 3.1: VISIBLE MOWN TURF Mown turf should be visible from the road, from the parking lot, and leading to the entrance of the business. Mown turf should occupy at least 50% of the front of the unpaved areas of the business site and at least 25% of the back of the unpaved area of the business site. For some businesses, mown turf may be necessary in additional locations for business reasons. For example, some food industries may require mown turf in a zone around buildings to discourage entry to the building by animal pests. Corollary 3.2 : FLOWERS AND TREES Flowering plants, and trees should dominate patches that are not mown turf. Flowering trees and other plants are most widely perceived as attractive and are more likely to be associated with good care. 13

15 Figure 10. The design and maintenance of habitat and non-habitat patches should make the amenity value of the landscape immediately apparent. This building facade and entry are framed with mown turf, and indigenous plants are chosen for their amenity and ecosystem values. Corollary 3.3: ENTRY VIEWS Design non-turf patches to frame the entry view to the building façade and entrance from roads and parking lots. Turf or low-growing plants can lead the eye to the entry from the street or parking lot. Corollary 3.4: CRISP EDGES Design crisp, clearly defined edges between turf patches and non-turf patches. Crisp edges also convey good care. They can be achieved by a continuous mown edge or be structural materials, like pavers or fences. Corollary 3.5: NATURAL VERSUS INDIGENOUS ECOSYSTEM Figure 11. Indigenous plants should be chosen to contribute to the appearance of care and order. Plants of some ecosystems, like Great Lakes alvars, may be difficult to design to achieve this appearance. Not all indigenous ecosystems are equally amenable to being designed to be perceived as amenity landscapes. Prairie, savanna, and stream may be most easily adapted to brownfield redevelopment designs where habitat is desirable. Wetland ecosystems also can be designed to create amenity. While Great Lakes alvar ecosystems make strong ecological analogues to some well-drained, highly alkaline brownfield sites, they may be more difficult to design for amenity values, particularly on smaller sites. 14

16 GLOSSARY Exposed to toxins. A possibility of exposure exists in plant parts, exposed soils, or by surface water connections to contaminated groundwater. Such exposure may be well below designated levels of acceptable human risk for the intended use of the brownfield. Design to discourage exposure to toxins merely assumes that some level of toxins may remain in some areas of the brownfield site. It employs the precautionary principle to minimize unrecognized risks to humans, risks to wildlife or pets, or risks that toxins may be spread by wildlife, pets, or human vectors. Contamination. Exposure to toxins that exceed designated levels of acceptable human risk and requiring remediation. Possible contamination. Low levels of multiple contaminants that aggregate to potential human risk, while no single contaminant is above designated levels and remediation is not required. Patches. A landscape element (frequently described by its ecosystem type - e.g., turf lawn, woodland, prairie, wetland) that is homogeneous at a scale less than the entire landscape and distinct from its surrounding landscape context. Patches can be clearly human-dominated (e.g., mown turf) or can be less intensively disturbed (e.g., a restored wetland). Patches vary widely in size and shape and the landscape can vary in the number and pattern of patches. Corridors. Landscape elements that are long and narrow; linear patches. Corridors often function as conduits to facilitate landscape flows, or they can be filters or barriers. Corridors can be very narrow (like a drainage swale) or much wider (like a railroad right-of-way). Flows. The movement of animals, plants, water, wind, energy, and materials through a patch, among patches, and through landscapes. Flows occur both vertically (like rain water percolating into the soil) and horizontally (like a seed blowing across a field). Clean areas. Relatively uncontaminated soils that are separated from underlying soil or water contamination by natural or constructed barriers. Habitat patches. Uncontaminated soils or areas that have a vegetative cover providing suitable resources (e.g., clean water, nutrients, cover, sunlight) for plants and animals to establish viable populations. Indigenous. Plants and animals that were present in a region of the Americas before European settlement. Plants and animals that tend to be well-adapted to local climate and soil conditions. Phytoremediation. The use of plants to remove, degrade, or sequester contaminants from soil or groundwater. Impervious. A cover type that allows no or negligible rainwater flow through (e.g., rooftops, common asphalt). Soil bioengineering. A method of shoreline and slope soil stabilization that combines mechanical, biological, and ecological concepts to prevent shallow slope failures and excessive streambank erosion. 15