STORMWATER MANAGEMENT - Baltimore City Department …



The reasons for this check list are:To guide the designer to justify how the criteria of “Environmental Site Design to the Maximum Extent Practicable” has been met . To guide the Baltimore City SWM/ESC Plans Review Section reviewers in their review. Glossary / AbbreviationsDA: drainage area - HSG: hydrologic soil group - SF: square feet- FT: feet-GWT: groundwater tableHotspots: land use or activity that generates higher concentrations of contaminants than are found in typical stormwater. PRACTICECRITERIAREASON NOT USEDMinimize impervious areaGreen RoofRoof Slope < 30% or 4:12Additional structural design necessaryPermeable pavementSlope < 5%HSG A, B, or C Soil boring and infiltration test requiredSub base invert at least 4 FT above GWT10 FT from buildingsNo HotspotsReinforced turfSlope < 5%Not on compacted fillNot suitable for heavy trafficNo HotspotsDisconnection of rooftop runoffSlope < 5%DA < 500 SFPervious area length > 15 FT Disconnection > 10 FT from downgradient impervious areaNot on compacted fillNo HotspotsDisconnection of non-rooftop runoffSlope <5%DA < 1000 SFPervious area length > 10 FT Disconnection > 10 FT from downgradient impervious areaNot on compacted fillNo HotspotsSheetflow to conservation areasSlope < 5%Conservation area > 20,000 SFWidth > 50 FTNot on compacted fillNo HotspotsRainwater harvestingMust allow dewatering by use or discharge to vegetated areaA water balance evaluation may be required.No use on Hotspots if water use is for irrigationSubmerged gravel wetlandsSuitable for high groundwater tableNo HotspotsLandscape infiltrationDA < 10,000 sq ftHSG A or BDepth from bottom to GWT > 4 FTSoil boring and infiltration test requiredNo HotspotsInfiltration bermsSlope < 10%No HotspotsDry wellsDA < 1,000 SFHSG A or B10 FT from buildingsSetback >100 FT from fill slopesSoil boring and infiltration test requiredNo HotspotsMicrobioretentionDA < 0.5 sq ftDepth from bottom to GWT > 4 FT ( >1 FT with underdrain)Soil boring and infiltration test requiredNo HotspotsRain gardensDA < 10,000 SF (2,000 SF for residential)No HotspotsSoil boring an infiltration test requiredDepth from bottom to GWT > 2 FTGrass swalesLinear applications only, must be as long as the treated surfaceNo HotspotsBioswalesHSG A or B unless using an underdrainSoil boring and infiltration test requiredNo HotspotsDepth from bottom to GWT > 2 FTWet swalesHigh groundwater tableNo HotspotsEnhanced filtersPart of bioretention, rain garden, or other infiltration practiceDepth from bottom to GWT > 4 FT ................
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