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{{alert|Filter strips, when vegetated, provide water quality benefits, may provide some stormwater volume reduction, and may provide typical benefits of vegetation, such as habitat, depending on the vegetation type.|alert-success}} | {{alert|Filter strips, when vegetated, provide water quality benefits, may provide some stormwater volume reduction, and may provide typical benefits of vegetation, such as habitat, depending on the vegetation type.|alert-success}} | ||
− | This page provides supplemental information on operation and maintenance (O&M) of vegetated filter strips. For basic information on O&M for filter strips, see [[Operation and maintenance (O&M) of filter strips]]. | + | This page provides supplemental information on operation and maintenance (O&M) of vegetated <span title="an area of permanent vegetation or other material used to reduce sediment, organics, nutrients, pesticides, and other contaminants from runoff and to maintain or improve water quality.> '''[https://stormwater.pca.state.mn.us/index.php?title=Overview_for_pretreatment_vegetated_filter_strips filter strips]'''</span>. For basic information on O&M for filter strips, see [[Operation and maintenance (O&M) of filter strips]]. |
==Maintenance activities== | ==Maintenance activities== | ||
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===Removing sediment and debris buildup=== | ===Removing sediment and debris buildup=== | ||
− | As sediment is deposited after rain events, it can alter the uniform slope and result in channelized flow, which reduces the effectiveness of the pretreatment vegetated filter strip and can result in additional maintenance such as regrading and replanting. Removing sediment should occur when deposited sediment creates channelized flow through the pretreatment vegetated filter strip, sediment accumulation reaches the level of the contributing ground surface or level spreader, or when the sediment increases the water depth above the height the vegetation. Sediment removal should be completed by sweeping with a stiff bristle broom or using a vacuum truck. If a significant amount of sediment accumulates on the pretreatment vegetated filter strip (more than 2 inches) and is not removed in a timely manner, the vegetation will die off and require reseeding/replanting. | + | As sediment is deposited after rain events, it can alter the uniform slope and result in <span title="Water flow focused into individual straight pathways rather than across a broad area (sheet flow)"> '''channelized flow'''</span>, which reduces the effectiveness of the pretreatment vegetated filter strip and can result in additional maintenance such as regrading and replanting. Removing sediment should occur when deposited sediment creates channelized flow through the pretreatment vegetated filter strip, sediment accumulation reaches the level of the contributing ground surface or <span title="Level Spreaders are measures that reduce the erosive energy of concentrated flows by distributing runoff as sheet flow to stabilized vegetative surfaces."> '''level spreader'''</span>, or when the sediment increases the water depth above the height the vegetation. Sediment removal should be completed by sweeping with a stiff bristle broom or using a vacuum truck. If a significant amount of sediment accumulates on the pretreatment vegetated filter strip (more than 2 inches) and is not removed in a timely manner, the vegetation will die off and require reseeding/replanting. |
− | Along with removing sediment buildup, removing trash and debris is required in the maintenance process. Trash and debris buildup, like sediment buildup, can increase the chance of channelized flows, cause clogging in downstream pipe or intake structures, and negatively impact the aesthetics. If cleaning is not conducted, this trash and debris can be flushed into the full-treatment BMP during a larger rain event, which will reduce its effectiveness and result in a costlier cleanup. | + | Along with removing sediment buildup, removing trash and debris is required in the maintenance process. Trash and debris buildup, like sediment buildup, can increase the chance of channelized flows, cause clogging in downstream pipe or intake structures, and negatively impact the aesthetics. If cleaning is not conducted, this trash and debris can be flushed into the full-treatment <span title="One of many different structural or non–structural methods used to treat runoff"> '''best management practice'''</span> (BMP) during a larger rain event, which will reduce its effectiveness and result in a costlier cleanup. |
===Preventing or minimizing washouts and erosion of the pretreatment vegetated filter strip=== | ===Preventing or minimizing washouts and erosion of the pretreatment vegetated filter strip=== | ||
− | To ensure that washout and erosion damage of the pretreatment vegetated filter strip does not occur, maintaining sufficient vegetation and a moderate slope per the design specifications is critical. Maintaining distribution of inflow (level spreader or otherwise), a slope of 6 percent or less, vegetation cover of at least 80 percent, and grass that is at least 3 inches long is recommended. | + | To ensure that <span title"the removal or erosion of material captured by a stormwater device, typically a result of subsequent high flow volumes or rates or inadequate maintenance of the device"> '''washout'''</span> and erosion damage of the pretreatment vegetated filter strip does not occur, maintaining sufficient vegetation and a moderate slope per the design specifications is critical. Maintaining distribution of inflow (level spreader or otherwise), a slope of 6 percent or less, vegetation cover of at least 80 percent, and grass that is at least 3 inches long is recommended. |
===Vegetation establishment=== | ===Vegetation establishment=== | ||
− | Establishing full and healthy vegetation is vital to ensuring that the pretreatment vegetated filter strip will perform as designed. For the best results, weeds should be removed from the bare soil before planting. To ensure that vegetation will become established and survive the winter freeze, a minimum of 60 days before the first expected frost should be allowed for the vegetation to grow. Soil stabilization practices such as erosion | + | Establishing full and healthy vegetation is vital to ensuring that the pretreatment vegetated filter strip will perform as designed. For the best results, weeds should be removed from the bare soil before planting. To ensure that vegetation will become established and survive the winter freeze, a minimum of 60 days before the first expected frost should be allowed for the vegetation to grow. Soil stabilization practices such as <span title="typically biodegradable, open-weave blankets that provide temporary cover and support for establishing vegetation on bare soil areas."> [https://stormwater.pca.state.mn.us/index.php?title=Erosion_prevention_practices_-_erosion_control_blankets_and_anchoring_devices '''erosion control blankets''']</span> should be used during vegetation establishment. To avoid damaging the emerging vegetation and causing site compaction, vehicle and foot traffic should not be allowed during the vegetation establishment phase. Achieving a minimum of 80 percent cover on the pretreatment vegetated filter strip, per the design guidelines, will ensure that the site is stabilized after construction. Following rain events, additional inspections and possible maintenance on the full-treatment BMP downstream of the pretreatment vegetated filter strip is recommended during the vegetation establishment phase. |
===Maintaining vegetation=== | ===Maintaining vegetation=== | ||
Maintaining adequate vegetation cover is critical to sustaining the design effectiveness and mitigating erosion of the pretreatment vegetated filter strip. As previously mentioned, a minimum of 80 percent vegetation and uniform cover is needed for the pretreatment vegetated filter strip to be effective. | Maintaining adequate vegetation cover is critical to sustaining the design effectiveness and mitigating erosion of the pretreatment vegetated filter strip. As previously mentioned, a minimum of 80 percent vegetation and uniform cover is needed for the pretreatment vegetated filter strip to be effective. | ||
− | Vegetation maintenance includes cleanup, mowing, invasive plant and weed removal, and quality checks. Cleanup, as mentioned above, requires removing excess sediment, debris, and trash. Large debris and trash can be removed by hand; smaller debris and sediment require sweeping with a stiff bristle broom or using a vacuum truck. To maintain the proper length for the vegetation, regular mowing must be conducted. Mowing should not be done when the ground is wet to reduce the chance of rutting from the wheels. The party in charge of mowing the pretreatment vegetated filter strip should be made aware that it is a BMP and that they should check for any signs of degradation (e.g., erosion, lack of vegetation) or need for additional maintenance. Mowing should be done as necessary to achieve grass heights of 3 to 4 inches. For additional mowing information, see the University of Minnesota website. Removing invasive plants and weeds will ensure that the planted vegetation remains healthy and full. Fertilizers should only be used in the vegetation establishment phase, because adding additional nutrients is counterproductive to using the pretreatment vegetated filter strip and permanent BMP. Establishing vegetation as quickly as possible and having healthy, dense vegetation is important. | + | Vegetation maintenance includes cleanup, mowing, <span title="An invasive species is an organism, including plants, that is not indigenous, or native, to a particular area and that can cause great economic and environmental harm."> '''invasive plant'''</span> and weed removal, and quality checks. Cleanup, as mentioned above, requires removing excess sediment, debris, and trash. Large debris and trash can be removed by hand; smaller debris and sediment require sweeping with a stiff bristle broom or using a vacuum truck. To maintain the proper length for the vegetation, regular mowing must be conducted. Mowing should not be done when the ground is wet to reduce the chance of rutting from the wheels. The party in charge of mowing the pretreatment vegetated filter strip should be made aware that it is a BMP and that they should check for any signs of degradation (e.g., erosion, lack of vegetation) or need for additional maintenance. Mowing should be done as necessary to achieve grass heights of 3 to 4 inches. For additional mowing information, [https://extension.umn.edu/lawns-and-landscapes/lawn-care see the University of Minnesota website]. Removing invasive plants and weeds will ensure that the planted vegetation remains healthy and full. Fertilizers should only be used in the vegetation establishment phase, because adding additional nutrients is counterproductive to using the pretreatment vegetated filter strip and permanent BMP. Establishing vegetation as quickly as possible and having healthy, dense vegetation is important. |
===Snow Storage=== | ===Snow Storage=== | ||
BMP areas generally should not be used as dedicated snow storage areas. If this is not possible, follow the following guidelines. | BMP areas generally should not be used as dedicated snow storage areas. If this is not possible, follow the following guidelines. | ||
− | Snow storage should not occur in areas designated as potential stormwater hotspots for road salt. | + | *Snow storage should not occur in areas designated as potential stormwater hotspots for road salt. |
− | + | *Areas designed for <span title="Infiltration Best Management Practices (BMPs) treat urban stormwater runoff as it flows through a filtering medium and into underlying soil, where it may eventually percolate into groundwater. The filtering media is typically coarse-textured and may contain organic material, as in the case of bioinfiltration BMPs."> [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_infiltration_Best_Management_Practices '''infiltration''']</span> should be protected from excessive snow storage where sand and salt is applied. | |
− | Areas designed for infiltration should be protected from excessive snow storage where sand and salt is applied. | + | *Specific snow storage areas should be assigned that will provide some <span title="Filtration Best Management Practices (BMPs) treat urban stormwater runoff as it flows through a filtering medium, such as sand or an organic material. They are generally used on small drainage areas (5 acres or less) and are primarily designed for pollutant removal. They are effective at removing total suspended solids (TSS), particulate phosphorus, metals, and most organics. They are less effective for soluble pollutants such as dissolved phosphorus, chloride, and nitrate."> [https://stormwater.pca.state.mn.us/index.php?title=Filtration '''filtration''']</span> before the stormwater reaches the practice areas. Note that chloride will not be removed or attenuated in filtration practices. |
− | Specific snow storage areas should be assigned that will provide some filtration before the stormwater reaches the practice areas. Note that | + | *When used for snow storage, or if used to treat parking lot runoff, the practice area should be planted with salt tolerant and non-woody plant species. |
− | + | *Practices should always be inspected for sand build-up on the surface following the spring melt event. | |
− | When used for snow storage, or if used to treat parking lot runoff, the practice area should be planted with salt tolerant and non-woody plant species. | ||
− | Practices should always be inspected for sand build-up on the surface following the spring melt event. | ||
==Maintenance agreements== | ==Maintenance agreements== | ||
− | Maintenance agreements (similar to site easements) are required for one party to define and enforce maintenance by another party and may be necessary to access the site to conduct maintenance on the pretreatment vegetated filter strip. A maintenance agreement is a legally binding agreement between two parties and is defined as “a nonpossessory right to use and/or enter onto the real property of another without possessing it.” Maintenance agreements are often required for the issuance of a permit for constructing a stormwater management feature and are written and approved by legal counsel. These maintenance agreements can be established for a defined period of time and often define the types of inspections and maintenance that are required for the pretreatment vegetated filter strip. If maintenance needs to be conducted because the party in charge of the maintenance failed per the maintenance agreement, the party responsible for routine maintenance must follow the agreed-upon reimbursement terms. Examples of three site maintenance agreements can be found at this link. | + | Maintenance agreements (similar to site easements) are required for one party to define and enforce maintenance by another party and may be necessary to access the site to conduct maintenance on the pretreatment vegetated filter strip. A maintenance agreement is a legally binding agreement between two parties and is defined as “a nonpossessory right to use and/or enter onto the real property of another without possessing it.” Maintenance agreements are often required for the issuance of a permit for constructing a stormwater management feature and are written and approved by legal counsel. These maintenance agreements can be established for a defined period of time and often define the types of inspections and maintenance that are required for the pretreatment vegetated filter strip. If maintenance needs to be conducted because the party in charge of the maintenance failed per the maintenance agreement, the party responsible for routine maintenance must follow the agreed-upon reimbursement terms. Examples of three site maintenance agreements [https://stormwater.pca.state.mn.us/index.php?title=Example_O%26M_plans,_checklists,_reports,_and_maintenance_agreements_for_vegetated_filter_strips can be found at this link]. |
==Additional References== | ==Additional References== | ||
− | *Abu-Zreig, M., R. P. Rudra, M. N. Lalonde, H. R. Whiteley, and N. K. Kaushik, 2004. Experimental Investigation of Runoff Reduction and Sediment Removal by Vegetated Filter Strips. Hydrological Processes, Vol. 18, No. 11, pp. 2029–2037. | + | *Abu-Zreig, M., R. P. Rudra, M. N. Lalonde, H. R. Whiteley, and N. K. Kaushik, 2004. ''Experimental Investigation of Runoff Reduction and Sediment Removal by Vegetated Filter Strips''. Hydrological Processes, Vol. 18, No. 11, pp. 2029–2037. |
*Barrett, M. E.; P. M. Walsh; J. F. Malina, Jr.; R. J. Charbeneau, 1998. Performance of Vegetative Controls for Treating Highway Runoff. Journal of Environmental Engineering, Vol. 124, No. 11, pp. 1121–1128. | *Barrett, M. E.; P. M. Walsh; J. F. Malina, Jr.; R. J. Charbeneau, 1998. Performance of Vegetative Controls for Treating Highway Runoff. Journal of Environmental Engineering, Vol. 124, No. 11, pp. 1121–1128. | ||
*Barret, M. E., A. Lantin, and S. Austrheim-Smith, 2004. Storm Water Pollutant Removal in Roadside Vegetated Buffer Strips. Transportation Research Record: Journal of the Transportation Research Board 1890, No. 1, pp. 129-140. | *Barret, M. E., A. Lantin, and S. Austrheim-Smith, 2004. Storm Water Pollutant Removal in Roadside Vegetated Buffer Strips. Transportation Research Record: Journal of the Transportation Research Board 1890, No. 1, pp. 129-140. |
This page provides supplemental information on operation and maintenance (O&M) of vegetated filter strips. For basic information on O&M for filter strips, see Operation and maintenance (O&M) of filter strips.
When inspections indicate that maintenance is necessary, the following sections provide guidelines to conduct the proper maintenance activities to restore the pretreatment vegetated filter strip to its design efficiency.
As sediment is deposited after rain events, it can alter the uniform slope and result in channelized flow, which reduces the effectiveness of the pretreatment vegetated filter strip and can result in additional maintenance such as regrading and replanting. Removing sediment should occur when deposited sediment creates channelized flow through the pretreatment vegetated filter strip, sediment accumulation reaches the level of the contributing ground surface or level spreader, or when the sediment increases the water depth above the height the vegetation. Sediment removal should be completed by sweeping with a stiff bristle broom or using a vacuum truck. If a significant amount of sediment accumulates on the pretreatment vegetated filter strip (more than 2 inches) and is not removed in a timely manner, the vegetation will die off and require reseeding/replanting.
Along with removing sediment buildup, removing trash and debris is required in the maintenance process. Trash and debris buildup, like sediment buildup, can increase the chance of channelized flows, cause clogging in downstream pipe or intake structures, and negatively impact the aesthetics. If cleaning is not conducted, this trash and debris can be flushed into the full-treatment best management practice (BMP) during a larger rain event, which will reduce its effectiveness and result in a costlier cleanup.
To ensure that washout and erosion damage of the pretreatment vegetated filter strip does not occur, maintaining sufficient vegetation and a moderate slope per the design specifications is critical. Maintaining distribution of inflow (level spreader or otherwise), a slope of 6 percent or less, vegetation cover of at least 80 percent, and grass that is at least 3 inches long is recommended.
Establishing full and healthy vegetation is vital to ensuring that the pretreatment vegetated filter strip will perform as designed. For the best results, weeds should be removed from the bare soil before planting. To ensure that vegetation will become established and survive the winter freeze, a minimum of 60 days before the first expected frost should be allowed for the vegetation to grow. Soil stabilization practices such as erosion control blankets should be used during vegetation establishment. To avoid damaging the emerging vegetation and causing site compaction, vehicle and foot traffic should not be allowed during the vegetation establishment phase. Achieving a minimum of 80 percent cover on the pretreatment vegetated filter strip, per the design guidelines, will ensure that the site is stabilized after construction. Following rain events, additional inspections and possible maintenance on the full-treatment BMP downstream of the pretreatment vegetated filter strip is recommended during the vegetation establishment phase.
Maintaining adequate vegetation cover is critical to sustaining the design effectiveness and mitigating erosion of the pretreatment vegetated filter strip. As previously mentioned, a minimum of 80 percent vegetation and uniform cover is needed for the pretreatment vegetated filter strip to be effective.
Vegetation maintenance includes cleanup, mowing, invasive plant and weed removal, and quality checks. Cleanup, as mentioned above, requires removing excess sediment, debris, and trash. Large debris and trash can be removed by hand; smaller debris and sediment require sweeping with a stiff bristle broom or using a vacuum truck. To maintain the proper length for the vegetation, regular mowing must be conducted. Mowing should not be done when the ground is wet to reduce the chance of rutting from the wheels. The party in charge of mowing the pretreatment vegetated filter strip should be made aware that it is a BMP and that they should check for any signs of degradation (e.g., erosion, lack of vegetation) or need for additional maintenance. Mowing should be done as necessary to achieve grass heights of 3 to 4 inches. For additional mowing information, see the University of Minnesota website. Removing invasive plants and weeds will ensure that the planted vegetation remains healthy and full. Fertilizers should only be used in the vegetation establishment phase, because adding additional nutrients is counterproductive to using the pretreatment vegetated filter strip and permanent BMP. Establishing vegetation as quickly as possible and having healthy, dense vegetation is important.
BMP areas generally should not be used as dedicated snow storage areas. If this is not possible, follow the following guidelines.
Maintenance agreements (similar to site easements) are required for one party to define and enforce maintenance by another party and may be necessary to access the site to conduct maintenance on the pretreatment vegetated filter strip. A maintenance agreement is a legally binding agreement between two parties and is defined as “a nonpossessory right to use and/or enter onto the real property of another without possessing it.” Maintenance agreements are often required for the issuance of a permit for constructing a stormwater management feature and are written and approved by legal counsel. These maintenance agreements can be established for a defined period of time and often define the types of inspections and maintenance that are required for the pretreatment vegetated filter strip. If maintenance needs to be conducted because the party in charge of the maintenance failed per the maintenance agreement, the party responsible for routine maintenance must follow the agreed-upon reimbursement terms. Examples of three site maintenance agreements can be found at this link.