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| {{Wikipedia p|Swale (geographical feature)}} | | {{cat header| Diggingtrenchswales.jpg | Swales| Swales are shallow troughlike depressions created to carry water during rainstorms and allow it to be absorbed by the soil.}} |
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| Swales, also know as bioswales are a shallow troughlike depression that's created to carry water during rainstorms or snow melts. -- Wiktionary. They are rapidly becoming a staple in the design of sustainable urban landscapes due to their number of advantages. Many governments are begining to require bioswales along with other "best management practices"
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| = Advantages =
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| * A means of [[groundwater recharge]], a favorite of [[Bill Mollison]] [[permaculture]] pioneer.
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| * Asthetically pleasing
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| * They treat water flowing through them
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| :* oils in the water stick to the foliage where they break down over time.
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| :* sediments are trapped and filtered out
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| =Design Recommendations=
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| * Single swales can not treat areas greater than 10 acres.
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| * Impractical on steep slopes.
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| * Requires thick vegitation.
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| * The swale should have a treatment area larger than 4% of the impervious surface it treats.
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| * The treatment depth should not exceed 2/3 the depth of the grass in the swale
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| * The dimensions of the swale should be checked with Manning's equation and a value of .25 for "Manning's n"
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| * Care should be taken in the design of the inlet and outlet of the swale
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| * A 6% down slope grade is ideal to insure that the velocity of the water in the swale does not become excessive.
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| * the side slopes of the swale should not exceed 3 to 1 (three feet over for every one foot down)
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| * The swale should have a maximum treatment width of 10ft, parallel swales should be used if greater widths are necessary.
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| == External links ==
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| * [http://www.hialeahfl.gov/dept/streets/stormwater/related-info/swale.htm Save the Swales - WHY MANAGE RUNOFF?] (the site of a local government in Florida).
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| * http://www.wikihow.com/Dig-Swales
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| *[http://www.eoainc.com/download/ACCWP_C3_Technical_Guidance_090506-300dpi.pdf Alameda County Stormwater Technical Guidance] has more details for the design of Bioswales and other best management practices.
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| {{stub}}
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| [[Category:Groundwater recharge]] | | [[Category:Groundwater recharge]] |
Parking lot swale.JPG 199 × 321; 20 KB
Street swale in seattle.JPG 432 × 235; 31 KB
