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Maximizing specific green infrastructure (GI) benefits requires design considerations prior to constructing the practice. While site limitations cannot always be overcome, the following recommendations maximize the GI benefit of bioretetnion. | Maximizing specific green infrastructure (GI) benefits requires design considerations prior to constructing the practice. While site limitations cannot always be overcome, the following recommendations maximize the GI benefit of bioretetnion. | ||
− | *Water quality | + | *[https://stormwater.pca.state.mn.us/index.php?title=Water_quality_benefits_of_Green_Stormwater_Infrastructure Water quality] |
**Maximize infiltration by designing with the maximum ponded depth that can be infiltrated in 48 hours, up to 1.5 feet (to protect vegetation). Where space allows, surface area can also be increased. Utilize multiple bioretention practices in series. On lower permeability soils where an underdrain is used, raise the underdrain to the maximum extent possible, allowing water stored in the bioretention media below the underdrain to drain in 48 hours. Use an upturned elbow in underdrained systems. | **Maximize infiltration by designing with the maximum ponded depth that can be infiltrated in 48 hours, up to 1.5 feet (to protect vegetation). Where space allows, surface area can also be increased. Utilize multiple bioretention practices in series. On lower permeability soils where an underdrain is used, raise the underdrain to the maximum extent possible, allowing water stored in the bioretention media below the underdrain to drain in 48 hours. Use an upturned elbow in underdrained systems. | ||
**For bioinfiltration (bioretention without an underdrain), use a high organic matter media to maximize pollutant removal | **For bioinfiltration (bioretention without an underdrain), use a high organic matter media to maximize pollutant removal | ||
**For biofiltration (bioretention with an underdrain), use a [https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_bioretention#Addressing_phosphorus_leaching_concerns_with_media_mixes media mix that does not export phosphorus] or [https://stormwater.pca.state.mn.us/index.php?title=Soil_amendments_to_enhance_phosphorus_sorption use an amendment to attenuate phosphorus]. | **For biofiltration (bioretention with an underdrain), use a [https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_bioretention#Addressing_phosphorus_leaching_concerns_with_media_mixes media mix that does not export phosphorus] or [https://stormwater.pca.state.mn.us/index.php?title=Soil_amendments_to_enhance_phosphorus_sorption use an amendment to attenuate phosphorus]. | ||
− | *Water quantity/supply | + | *[https://stormwater.pca.state.mn.us/index.php?title=Water_quantity_and_hydrology_benefits_of_Green_Stormwater_Infrastructure Water quantity/supply] |
**Maximize infiltration | **Maximize infiltration | ||
**Utilize [http://chesapeakestormwater.net/wp-content/uploads/downloads/2014/03/Internal-Water-Storage-for-Bioretention-2009.pdf internal water storage] | **Utilize [http://chesapeakestormwater.net/wp-content/uploads/downloads/2014/03/Internal-Water-Storage-for-Bioretention-2009.pdf internal water storage] | ||
**Maximize water storage in media | **Maximize water storage in media | ||
− | *Climate resiliency | + | *[https://stormwater.pca.state.mn.us/index.php?title=Climate_benefits_of_Green_Stormwater_Infrastructure Climate resiliency] |
**Select species that are more likely to survive in the anticipated future climate | **Select species that are more likely to survive in the anticipated future climate | ||
**Select species that efficiently sequester carbon | **Select species that efficiently sequester carbon | ||
**Ensure trees receive adequate water | **Ensure trees receive adequate water | ||
**To reduce heat island effects, select vegetation that reflects solar energy, absorbs solar energy and releases it slowly, or that maximizes evapotranspiration [http://www1.nyc.gov/assets/orr/images/content/header/ORR_ClimateResiliencyDesignGuidelines_PRELIMINARY_4_21_2017.pdf NYC Mayor’s Office of Recovery and Resiliency] | **To reduce heat island effects, select vegetation that reflects solar energy, absorbs solar energy and releases it slowly, or that maximizes evapotranspiration [http://www1.nyc.gov/assets/orr/images/content/header/ORR_ClimateResiliencyDesignGuidelines_PRELIMINARY_4_21_2017.pdf NYC Mayor’s Office of Recovery and Resiliency] | ||
− | **Oversize storage area to account for increased precipitation. [http://wildlife.ohiodnr.gov/portals/wildlife/PDFs/Public%20Areas/BRC%20and%20PP%20Climate%20Change%20(US%20units).pdf Winston (2016)] recommends oversizing by 33-45% for bioretention in northern Ohio. Oversizing can also be accomplished by reducing loading to individual bioretention practices. | + | **Oversize storage area to account for increased precipitation. [http://wildlife.ohiodnr.gov/portals/wildlife/PDFs/Public%20Areas/BRC%20and%20PP%20Climate%20Change%20(US%20units).pdf Winston (2016)] recommends oversizing by 33-45% for bioretention in northern Ohio. Oversizing can also be accomplished by reducing loading to individual bioretention practices. ([https://www.hort.cornell.edu/uhi/research/articles/Maple%20paper.pdf], [https://academic.oup.com/forestry/article/88/1/13/2756020], [http://www.righttrees4cc.org.uk/], [http://www.mortonarb.org/files/Managing%20Urban%20Forests%20Schedule%20only.pdf], [https://www.fs.usda.gov/ccrc/topics/urban-forests-and-climate-change], [https://toolkit.climate.gov/case-studies/fortifying-chicagos-urban-forest]) |
− | [https://www.hort.cornell.edu/uhi/research/articles/Maple%20paper.pdf] | + | *[https://stormwater.pca.state.mn.us/index.php?title=Wildlife_habitat_and_biodiversity_benefits_of_Green_Stormwater_Infrastructure Habitat] |
− | [https://academic.oup.com/forestry/article/88/1/13/2756020] | ||
− | [http://www.righttrees4cc.org.uk/] | ||
− | [http://www.mortonarb.org/files/Managing%20Urban%20Forests%20Schedule%20only.pdf] | ||
− | [https://www.fs.usda.gov/ccrc/topics/urban-forests-and-climate-change] | ||
− | [https://toolkit.climate.gov/case-studies/fortifying-chicagos-urban-forest] | ||
− | |||
− | *Habitat | ||
**Utilize native, perennial vegetation, including shrubs and trees if space allows. For more information, see [[Minnesota plant lists]]. | **Utilize native, perennial vegetation, including shrubs and trees if space allows. For more information, see [[Minnesota plant lists]]. | ||
**Incorporate landscape features, such as form, plant layering, and plant density. For more information on landscape factors, see [https://scisoc.confex.com/scisoc/2015am/webprogram/Paper91320.html this presentation] by Dr. Steven Rodie (University of Nebraska at Omaha) | **Incorporate landscape features, such as form, plant layering, and plant density. For more information on landscape factors, see [https://scisoc.confex.com/scisoc/2015am/webprogram/Paper91320.html this presentation] by Dr. Steven Rodie (University of Nebraska at Omaha) | ||
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*Health benefits | *Health benefits | ||
**Choose locations for bioretention that enhance aesthetics | **Choose locations for bioretention that enhance aesthetics | ||
− | **Perennial vegetation, particularly shrubs and trees, provide health | + | **Perennial vegetation, particularly shrubs and trees, provide health benefits related to filtering [https://stormwater.pca.state.mn.us/index.php?title=Air_quality_benefits_of_Green_Stormwater_Infrastructure air pollutants]. See [https://www.theatlantic.com/health/archive/2014/07/trees-good/375129/ The Health Benefits of Trees] (Hamblin, 2014) |
*Economic benefits | *Economic benefits | ||
**Choose the correct BMP. There is no comprehensive guidance on this, but an important factor in selecting BMPs is cost per unit treatment. This depends on the goal of the project, but examples of costs may be dollars per cubic foot of water treated or per pound of pollutant. Barr Engineering [https://www.pca.state.mn.us/sites/default/files/p-gen3-13x.pdf completed a report] that provides information on construction costs, maintenance costs, and land requirements for several stormwater BMPs. The report includes references to other useful reports. Information in the report can be used to match the site goals (e.g. infiltration vs. filtration) and site conditions (e.g. large vs. small site) to the most cost-efficient BMP. | **Choose the correct BMP. There is no comprehensive guidance on this, but an important factor in selecting BMPs is cost per unit treatment. This depends on the goal of the project, but examples of costs may be dollars per cubic foot of water treated or per pound of pollutant. Barr Engineering [https://www.pca.state.mn.us/sites/default/files/p-gen3-13x.pdf completed a report] that provides information on construction costs, maintenance costs, and land requirements for several stormwater BMPs. The report includes references to other useful reports. Information in the report can be used to match the site goals (e.g. infiltration vs. filtration) and site conditions (e.g. large vs. small site) to the most cost-efficient BMP. |
Tree trenches and tree boxes are vegetated engineered landscape practices designed to filter or infiltrate stormwater runoff. They can be incorporated into a wide variety of landscaped areas, including ultra-urban landscapes. Technically, tree boxes and tree trenches are bioretention practices, but their design, construction, maintenance, and benefits merit a separate discussion. Note that this page does not discuss urban forests and use of trees in natural landscape settings. These are discussed on a separate page.
Benefit | Effectiveness | Notes |
---|---|---|
Water quality | Benefits are maximized for bioinfiltration. Biofiltration may export phosphorus if not designed properly. | |
Water quantity/supply | Bioinfiltration helps mimic natural hydrology. Some rate control benefit. | |
Energy savings | ||
Climate resiliency | Provides some rate control. Impacts on carbon sequestration are uncertain. | |
Air quality | ||
Habitat improvement | Use of perennial vegetation and certain media mixes promote invertebrate communities. | |
Community livability | Aesthetically pleasing and can be incorporated into a wide range of land use settings. | |
Health benefits | ||
Economic savings | Generally provide cost savings vs. conventional practices over the life of the practice. | |
Macroscale benefits | Individual practices are typically microscale, but multiple practices, when incorporated into a landscape design, provide macroscale benefits such as wildlife corridors. | |
Level of benefit: ◯ - none; ◔; - small; ◑ - moderate; ◕ - large; ● - very high |
Because of their diversity and use of vegetation, tree trench and tree box practices provide multiple green infrastructure benefits.
Tree trenches and tree boxes are bioretention practices. Therefore, design considerations to enhance green infrastructure benefits of tree trenches and tree boxes are similar to design recommendations for bioretention.
Maximizing specific green infrastructure (GI) benefits requires design considerations prior to constructing the practice. While site limitations cannot always be overcome, the following recommendations maximize the GI benefit of bioretetnion.
A tree ordinance is a tool to help protect and manage a community’s trees. It can be designed to regulate various aspects of tree planting, removal, and maintenance on public and private property within a municipality. For more general information on tree ordinances, link here: [8], [9], or [10].
An urban forest master plan provides a road map for managing trees and the tree canopy in an urban area. The master plan typically includes detailed information, recommendations, and resources needed to manage an urban forest. An important component of a good forest master plan is engaging citizens and other stakeholders in the value and care of the urban forest.
A master plan may contain some or all of the following elements.
Example master plans are found at the following links.