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--- bioretention_device [2022/05/06 09:14] – created admin
+++ bioretention_device [2025/09/30 14:49] (current) – admin
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 ====== Bioretention Device ======
+:!: The current version of WinSLAMM (10.5.0) overestimates evapotranspiration (ET) volume. Until a fix is implemented, ET may not be turned on in the model. :!:
 Bioretention devices are infiltration devices used for the treatment and infiltration of stormwater runoff.  A bioretention basin is made up of several layers, which treat stormwater as it is filtered.  These basins remove pollutants and reduce runoff volume and temperature.  Bioretention basins can be used as a stand-alone method of stormwater treatment or in conjunction with other stormwater management practices.
-=====Advantages=====
+{{ :wiki:photos:bioretention2.jpg?600 |}}
+**Advantages**
   *Promotes infiltration of stormwater
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   *Reduces temperature impacts of runoff
-=====Disadvantages=====
+**Disadvantages**
   *Not suitable for construction site erosion control
@@ Line 21: / Line 25: @@
 =====Design=====
-For complete design of bioretention basins, please refer to DNR Standard 1004.  Bioretention basins should be designed with careful consideration given to each of the following key components: drainage area and pretreatment, ponding zone, vegetation and mulch layer, engineered soil layer, storage layer, underdrain, and sand/native soil interface layer (refer to Figure 1).
+For complete design of bioretention basins, please refer to DNR Standard 1004.  Bioretention basins should be designed with careful consideration given to each of the following key components: drainage area and pretreatment, ponding zone, vegetation and mulch layer, engineered soil layer, storage layer, underdrain, and sand/native soil interface layer.
+{{ :wiki:images:schematics:bioretention_basin.png?1000 |}}
 ====Drainage Area And Pretreatment====
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 ====Storage Layer====
-The storage layer promotes infiltration.  Since infiltration is the only way water is able to exit the storage layer, it is an important component of the bioretention facility.  A storage layer is necessary when the native soil has an infiltration rate of less than 3.6 inches per hour.  The maximum depth of the storage area is 48 inches and must be such that the total device drain time is 72 hours or less.  The storage layer may be composed of sand or clear double-washed stone of uniform size (i.e. WisDOT coarse aggregate #2).
+The storage layer promotes infiltration.  Since infiltration is the only way water is able to exit the storage layer, it is an important component of the bioretention facility.  A storage layer is necessary when the native soil has an infiltration rate of less than 3.6 inches per hour.  The maximum depth of the storage area is 48 inches and must be such that the total device drain time is 72 hours or less.  The storage layer may be composed of sand or clear double-washed stone of uniform size (e.g. WisDOT coarse aggregate #2).
 ====Underdrain====
@@ Line 52: / Line 58: @@
 An interface layer is necessary when the infiltration rate of the native soil is less than 3.6 inches per hour.  The interface layer shall be formed by a layer of sand three inches deep, which is vertically mixed with the native soil to a depth of 2 to 4 inches.
-=====Other Considerations=====
+====Other Considerations====
 To regulate the maximum ponding depth of the basin, overflow devices such as a weir or standpipe should be installed.  The discharge from these overflow devices must be directed to a stable outlet.
@@ Line 58: / Line 64: @@
 =====Construction=====
-*Runoff shall not be allowed in the basin until after the tributary area is stabilized
+  *Runoff shall not be allowed in the basin until after the tributary area is stabilized
-*Construction of the basin should only occur during suitable site conditions - if construction of the basin occurs during saturated soil conditions, the soil in the device could be unnecessarily compacted
+  *Construction of the basin should only occur during suitable site conditions - if construction of the basin occurs during saturated soil conditions, the soil in the device could be unnecessarily compacted
-*Compaction of the soils used for the bioretention device must be avoided - heavy equipment may not be used in the construction of the basin
+  *Compaction of the soils used for the bioretention device must be avoided - heavy equipment may not be used in the construction of the basin
-*The engineered soil shall be premixed before placement and be dry enough to prevent clumping and compaction
+  *The engineered soil shall be premixed before placement and be dry enough to prevent clumping and compaction
-*The engineered soil should be placed in several 12-inch deep lifts
+  *The engineered soil should be placed in several 12-inch deep lifts
-*The basin should be mulched before the planting of the vegetation in order to prevent compaction
+  *The basin should be mulched before the planting of the vegetation in order to prevent compaction
 =====Maintenance=====
-*Accumulated sediment in pretreatment devices should be removed as needed
+  *Accumulated sediment in pretreatment devices should be removed as needed
-*Bioretention basins should be inspected semi-annually
+  *Bioretention basins should be inspected semi-annually
-*Additional mulch should be added at least once a year and as needed to maintain 2-3 inches of cover
+  *Additional mulch should be added at least once a year and as needed to maintain 2-3 inches of cover
-*Bioretention basins should be inspected monthly for signs of erosion and sediment accumulation - all necessary repairs should be performed immediately
+  *Bioretention basins should be inspected monthly for signs of erosion and sediment accumulation - all necessary repairs should be performed immediately
 =====Method to Determine Practice Efficiency=====
-A properly designed bioretention basin that has been sized to meet the applicable infiltration performance standard is assumed to have a sediment reduction efficiency of 80% and oil and grease removal that meets county treatment standards.
+[[http://www.winslamm.com/|WinSLAMM]], [[https://dnr.wi.gov/topic/stormwater/standards/recarga.html|RECARGA]] or other approved model must be used to determine the performance of this practice.  Additional information on the modeling of infiltration practices is found on the [[Infiltration Guidance]] page.
-In order to determine the infiltration performance of this practice [[http://www.winslamm.com/|WinSLAMM]], [[https://dnr.wi.gov/topic/stormwater/standards/recarga.html|RECARGA]] or other approved models may be used.  Additional information regarding acceptable modeling of infiltration practices is found on the [[Infiltration Guidance]] page.
 ===References===
-* [[https://dnr.wi.gov/topic/stormwater/documents/1004Bioretention.pdf|Wisconsin DNR Bioretention for Infiltration Conservation Practice Standard 1001]]
+[[https://dnr.wisconsin.gov/sites/default/files/topic/Stormwater/1004Bioretention.pdf|Wisconsin DNR Bioretention for Infiltration Conservation Practice Standard 1004]]
+{{ :wiki:flyers:bioretention_basin_flyer.pdf | Bioretention Basin Guidance for Owners}}
+{{ ::identification_of_common_wisconsin_weeds.pdf |Identification of Common Wisconsin Weeds}}