Difference between revisions of "Assessing the performance of swales"
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| − | + | [[File:Pdf image.png|100px|thumb|alt=pdf image|<font size=3>[https://stormwater.pca.state.mn.us/index.php?title=File:Assessing_the_performance_of_swales_-_Minnesota_Stormwater_Manual_May_2022.pdf Download pdf]</font size>]] | |
| + | [[File:General information page image.png|right|100px|alt=image]] | ||
| + | [[File:Swale filled.png|thumb|300px|alt=photo of swale with water|<font size=3>A properly functioning swale should drain within 48 hours of a runoff event</font size>]] | ||
| − | + | {{alert|Swales can be an important tool for retention and detention of stormwater runoff. Because they utilize vegetation, swales provide additional benefits, including cleaner air, carbon sequestration, improved biological habitat, and aesthetic value.|alert-success}} | |
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| − | Level 1 activities do not produce numerical performance data that could be used to obtain a stormwater management credit. BMP owners and operators who are interested in using data obtained from Levels 2 and 3 should consult with the MPCA or other regulatory agency to determine if the results are appropriate for credit calculations. Level 4, | + | <span title="Are configured as shallow, linear channels. They typically have vegetative cover such as turf or native perennial grasses"> [https://stormwater.pca.state.mn.us/index.php?title=Dry_swale_(Grass_swale) '''Swales''']</span> retain solids and associated pollutants by settling and <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 '''filtering''']</span>. A typical method for assessing the performance of of BMPs with underdrains is therefore measuring and comparing pollutant concentrations at the <span title="Influent typically refers to the water entering a stormwater bmp. It refers to water that has not been treated by the device, though the water may have received treatment from an upstream bmp"> '''influent'''</span> and <span title="Effluent typically refers to the water exiting a stormwater BMP"> '''effluent'''</span>. If the swale is designed for infiltration, see [[Assessing the performance of bioretention]]. |
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| + | An [http://stormwaterbook.safl.umn.edu/ online manual] for assessing BMP treatment performance was developed in 2010 by Andrew Erickson, Peter Weiss, and John Gulliver from the University of Minnesota and St. Anthony Falls Hydraulic Laboratory. The manual advises on a four-level process to assess the performance of a Best Management Practice. | ||
| + | *Level 1: [https://stormwaterbook.safl.umn.edu/assessment-programs/visual-inspection Visual Inspection]. This includes assessments for infiltration practices and for [http://stormwaterbook.safl.umn.edu/filtration-practices/visual-inspection-filtration-practices filtration practices]. The website includes links to a downloadable checklist. | ||
| + | *Level 2: [https://stormwaterbook.safl.umn.edu/assessment-programs/capacity-testing Capacity Testing]. Level 2 testing can be applied to both infiltration and filtration practices. | ||
| + | *Level 3: [https://stormwaterbook.safl.umn.edu/assessment-programs/synthetic-runoff-testing Synthetic Runoff Testing] for infiltration and filtration practices. Synthetic runoff test results can be used to develop an accurate characterization of pollutant retention or removal, but can be limited by the need for an available water volume and discharge. | ||
| + | *Level 4: [https://stormwaterbook.safl.umn.edu/assessment-programs/monitoring Monitoring for infiltration] or filtration practices | ||
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| + | Level 1 activities do not produce numerical performance data that could be used to obtain a stormwater management <span title="The stormwater runoff volume or pollutant reduction achieved toward meeting a runoff volume or water quality goal."> [https://stormwater.pca.state.mn.us/index.php?title=Overview_of_stormwater_credits '''credit (stormwater credit)''']</span>. BMP owners and operators who are interested in using data obtained from Levels 2 and 3 should consult with the MPCA or other regulatory agency to determine if the results are appropriate for credit calculations. Level 4, monitoring, is the method most frequently used for assessment of the performance of a BMP. | ||
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| + | The adjacent table summarizes the four levels of assessment. | ||
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| + | {{:Levels of assessment for stormwater best management practices (stormwater control measures)}} | ||
Use these links to obtain detailed information on the following topics related to BMP performance monitoring: | Use these links to obtain detailed information on the following topics related to BMP performance monitoring: | ||
| − | *[http://stormwaterbook.safl.umn.edu | + | *[http://stormwaterbook.safl.umn.edu/developing-assessment-program Developing an Assessment Program] |
| − | *[ | + | *[https://stormwaterbook.safl.umn.edu/water-budget-measurement Water Budget Measurement] |
| − | *[ | + | *[https://stormwaterbook.safl.umn.edu/sampling-methods Sampling Methods] |
| − | *[ | + | *[https://stormwaterbook.safl.umn.edu/analysis-water-and-soils Analysis of Water and Soils] |
| − | *[ | + | *[https://stormwaterbook.safl.umn.edu/data-analysis Data Analysis for Monitoring] |
| + | <noinclude> | ||
| + | ==Related pages== | ||
| + | *[[Overview for filtration]] | ||
| + | *[[Types of filtration]] | ||
| + | *[[Design criteria for filtration]] | ||
| + | *[[Construction specifications for filtration]] | ||
| + | *[[Assessing the performance of swales]] | ||
| + | *[[Assessing the performance of sand (media) filters]] | ||
| + | *[[Operation and maintenance of filtration]] | ||
| + | *[[Calculating credits for sand filter]] | ||
| + | *[[Calculating credits for swale]] | ||
| + | *[[Cost-benefit considerations for filtration]] | ||
| + | *[[References for filtration]] | ||
| − | + | Links to pages discussing assessment of other BMPs can be found at [http://stormwater.pca.state.mn.us/index.php/Category:Assessing_performance this page]. | |
| − | + | [[Category:Level 3 - Best management practices/Specifications and details/Assessing performance]] | |
| − | [[Category:Assessing performance]] | ||
</noinclude> | </noinclude> | ||
Latest revision as of 15:26, 27 December 2022
Green Infrastructure: Swales can be an important tool for retention and detention of stormwater runoff. Because they utilize vegetation, swales provide additional benefits, including cleaner air, carbon sequestration, improved biological habitat, and aesthetic value.
Swales retain solids and associated pollutants by settling and filtering. A typical method for assessing the performance of of BMPs with underdrains is therefore measuring and comparing pollutant concentrations at the influent and effluent. If the swale is designed for infiltration, see Assessing the performance of bioretention.
An online manual for assessing BMP treatment performance was developed in 2010 by Andrew Erickson, Peter Weiss, and John Gulliver from the University of Minnesota and St. Anthony Falls Hydraulic Laboratory. The manual advises on a four-level process to assess the performance of a Best Management Practice.
- Level 1: Visual Inspection. This includes assessments for infiltration practices and for filtration practices. The website includes links to a downloadable checklist.
- Level 2: Capacity Testing. Level 2 testing can be applied to both infiltration and filtration practices.
- Level 3: Synthetic Runoff Testing for infiltration and filtration practices. Synthetic runoff test results can be used to develop an accurate characterization of pollutant retention or removal, but can be limited by the need for an available water volume and discharge.
- Level 4: Monitoring for infiltration or filtration practices
Level 1 activities do not produce numerical performance data that could be used to obtain a stormwater management credit (stormwater credit). BMP owners and operators who are interested in using data obtained from Levels 2 and 3 should consult with the MPCA or other regulatory agency to determine if the results are appropriate for credit calculations. Level 4, monitoring, is the method most frequently used for assessment of the performance of a BMP.
The adjacent table summarizes the four levels of assessment.
Levels of assessment for stormwater best management practices (stormwater control measures)
Link to this table
| Level | Title | Objectives | Relative | Typical elapsed time | Advantages | Disadvantages |
|---|---|---|---|---|---|---|
| 1 | Visual Inspection | Determine if stormwater BMP is malfunctioning | 1 | 1 day | Quick, inexpensive | Limited knowledge gained |
| 2 | Capacity testing | Determine infiltration or sedimentation capacity and rates | 10 | 1 week | Less expensive, no equipment left in field | Limited to infiltration and sedimentation capacity/rates, uncertainties can be substantial |
| 3 | Simulated runoff testing | Determine infiltration rates, capacity, and pollutant removal performance | 10-100 | 1 week to 1 month | Controlled experiments, more accurate with fewer tests required for statistical significance as compared to monitoring, no equipment left in field | Cannot be used without sufficient water supply, limited scope |
| 4 | Monitoring | Determine infiltration rates, capacity, and pollutant removal performance | 400 | 14 months | Most comprehensive. Assess stormwater BMP within watershed without modeling | Uncertainty in results due to lack of control and number of variables, equipment left in field |
Use these links to obtain detailed information on the following topics related to BMP performance monitoring:
- Developing an Assessment Program
- Water Budget Measurement
- Sampling Methods
- Analysis of Water and Soils
- Data Analysis for Monitoring
Related pages
- Overview for filtration
- Types of filtration
- Design criteria for filtration
- Construction specifications for filtration
- Assessing the performance of swales
- Assessing the performance of sand (media) filters
- Operation and maintenance of filtration
- Calculating credits for sand filter
- Calculating credits for swale
- Cost-benefit considerations for filtration
- References for filtration
Links to pages discussing assessment of other BMPs can be found at this page.
This page was last edited on 27 December 2022, at 15:26.