Requirements, recommendations and information for using bioretention BMPs in the MIDS calculator Revision as of 16:23, 6 May 2013 by Mtrojan (talk | contribs) (Created page with "#Required *3 foot separation from the bottom of the bioretention system to seasonal high water table *Use most restrictive infiltration rate within 3 feet of the bottom of the...")(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff) Requirements, recommendations and information for using bioretention BMPs in the MIDS calculator

1. Required

• 3 foot separation from the bottom of the bioretention system to seasonal high water table
• Use most restrictive infiltration rate within 3 feet of the bottom of the BMP
• Drawdown time of 24 hours for trout streams
• For measured infiltration rates, apply a safety factor of 2 (2.5 for permeable pavement)
• Pretreatment

1. Recommend

• 5 acre or less for contributing area
• Maximum ponding depth of 18 inches, reduced to 6 inches if there is no site information (4 feet for infiltration basin)
• Field tested infiltration rates over table values

1. Information – provide links to the following*Guidance on determining infiltration rates

• Information site constraints (shallow soil, karst, etc.)
• Information on assessing BMPs
• Information on design metrics (high flow bypass, ponding depths, drawn down)
• Guidance on pretreatment
• Information on soil mixes
• Plant information, including species list that show water tolerance, potential effects of different species on infiltration rates, planting guidance
• Construction specifications
• Information on operation and maintenance

• 3 foot separation from the bottom of the bioretention system to seasonal high water table
• Use most restrictive infiltration rate within 3 feet of the bottom of the BMP
• Drawdown time of 24 hours for trout streams
• For measured infiltration rates, apply a safety factor of 2 (2.5 for permeable pavement)
• Pretreatment

1. Recommend

• 5 acre or less for contributing area
• Maximum ponding depth of 18 inches, reduced to 6 inches if there is no site information (4 feet for infiltration basin)
• Field tested infiltration rates over table values

1. Information – provide links to the following

• Guidance on determining infiltration rates
• Information site constraints (shallow soil, karst, etc.)
• Information on assessing BMPs
• Information on design metrics (high flow bypass, ponding depths, drawn down)
• Guidance on pretreatment
• Information on soil mixes
• Plant information, including species list that show water tolerance, potential effects of different species on infiltration rates, planting guidance
• Construction specifications
• Information on operation and maintenance