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--- infiltration_modeling [2022/05/06 10:22] – admin
+++ infiltration_modeling [2025/09/30 14:48] (current) – admin
@@ Line 1: / Line 1: @@
 ====== Infiltration Modeling ======
+:!: 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. :!:
 =====Regulatory Approach to Infiltration=====
@@ Line 22: / Line 24: @@
 Infiltration practices must be designed to meet the average annual infiltration goals included in the Dane County Erosion Control and Stormwater Management Ordinance.  Infiltration practice design takes into account the physical characteristics of the site such as: water table, soil types, limiting layers, and tributary land use.  In addition, infiltration practices may serve a dual purpose by mitigating thermal impacts.  [[bioretention device|Bioretention devices]] are often designed to achieve the county requirement for oil and grease treatment and sediment removal.
-The design of all infiltration practices designed to meet ordinance requirements shall comply with the information in this manual and applicable DNR conservation practice [[https://dnr.wi.gov/topic/stormwater/standards/postconst_standards.html|standards]].
+The design of all infiltration practices designed to meet ordinance requirements shall comply with the information in this manual, the [[infiltration guidance]] page and applicable  [[https://dnr.wi.gov/topic/stormwater/standards/postconst_standards.html|DNR conservation technical standards]].
 =====Target Stay-On Requirement=====
-Before an infiltration practice can be designed and sized the target stay-on requirement must be determined.  The target stay-on is dependent upon the predevelopment curve number (CN).  Target stay-on for residential and non-residential developments, for a range of predevelopment CNs, can be determined using Figure 1.
+Before an infiltration practice can be designed and sized the target stay-on requirement must be determined.  The target stay-on is dependent upon the predevelopment curve number (CN).  Target stay-on for residential and non-residential developments, for a range of predevelopment CNs, can be determined using the figure below.
 \\
-[{{ :wiki:images:target_stay_on.jpg |Figure 1: Target stay-on requirements}}]
+{{:wiki:images:target_stay_on.jpg?800}}
 \\
-The target stay-on requirement is given in depth (inches per year), but it may be advantageous to convert this depth to a volume (cubic feet per year).  A conversion equation is provided below.
+The target stay-on requirement is given in depth (inches per year), but it may be advantageous to convert this depth to a volume (cubic feet per year) using the equation below.
-----
 T<sub>v</sub> = (T<sub>d</sub> / 12) * A<sub>s</sub>
@@ Line 44: / Line 44: @@
 T<sub>d</sub> = Target stay-on depth, inches\\
 A<sub>s</sub> = Area of site, ft<sup>2</sup>
-----
 =====Target Recharge Requirement=====
@@ Line 52: / Line 50: @@
 =====Approved Models for Calculating Infiltration and Recharge=====
+====WinSLAMM====
+WinSLAMM (Source Loading and Management Model for Windows) was developed to evaluate nonpoint source pollutant loading in urban areas using small storm hydrology. The model and parameter files are made available through the DNR [[https://dnr.wi.gov/topic/stormwater/standards/slamm.html|website]].
+The model uses series of normal rainfall events to calculate the pollutant loading and runoff volumes generated. The user is able to route runoff through a  approved control devices, such as [[infiltration basin|infiltration basins]], [[bioretention device|bioretention devices]],  [[wet pond|wet ponds]], [[permeable pavement]], or catchbasins to determine how effectively these devices remove pollutants and infiltrate stormwater.
+WinSLAMM is an approved model for calculating infiltration and sediment control.
 ====RECARGA====
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 ===Calculating Recharge===
 The recharge calculation is based upon the RECARGA model output, ‘Recharge’.  An example recharge calculation is provided below.
-----
 R<sub>Post</sub> = R<sub>F</sub>+R<sub>T</sub>
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 P<sub>p</sub> = Percent pervious\\
 R<sub>Native</sub> = Site recharge rate, in/yr (from LWRD viewer)
-----
-====WinSLAMM====
-WinSLAMM (Source Loading and Management Model for Windows) was developed to evaluate nonpoint source pollutant loading in urban areas using small storm hydrology. The model and parameter files are made available through the DNR [[https://dnr.wi.gov/topic/stormwater/standards/slamm.html|website]].
-The model uses series of normal rainfall events to calculate the pollutant loading and runoff volumes generated. The user is able to route runoff through a  approved control devices, such as [[infiltration basin|infiltration basins]], [[bioretention basin|bioretention basins]],  [[wet basin|wet basins]], [[pervious pavement]], or catchbasins to determine how effectively these devices remove pollutants and infiltrate stormwater.
-WinSLAMM is an approved model for calculating infiltration and sediment control.
 =====Modeling Assumptions and Guidance=====
-*As with the use of any modeling software, it is important to understand the underlying principals and assumptions used to generate the model’s results.  Designers utilizing RECARGA or WinSLAMM modeling software are expected to read and understand the user manual prior to submitting plans that include modeling results.
+As with the use of any modeling software, it is important to understand the underlying principals and assumptions used to generate the model’s results.  Designers utilizing RECARGA or WinSLAMM modeling software are expected to read and understand the user manual prior to submitting plans that include modeling results.
-*The DNR conservation practice standard [[https://dnr.wi.gov/topic/stormwater/documents/1002SiteEvalForInfiltr.pdf|1002]] must be used to determine all design infiltration rates.
+The DNR's Technical Standard [[https://dnr.wisconsin.gov/sites/default/files/topic/Stormwater/1002SiteEvalForInfiltr.pdf|Site Evaluation for Stormwater Infiltration 1002]] must be used to determine all design infiltration rates.
-*Guidance for designing infiltration facilities can be found on the [[infiltration guidance]] page.
+Guidance for designing infiltration facilities can be found on the [[infiltration guidance]] page.