Stormwater Quality Design Manual (May 2007) - City of Sacramento ...

Runoff Treatment Control Measure Fact SheetStormwater PlanterDescriptionA stormwater planter is a low-lying vegetated planterthat receives runoff from roof drains or adjoiningpaved areas. A shallow surcharge zone above thevegetated surface temporarily stores stormwater (thewater quality volume, WQV). The accumulated runoffgradually infiltrates into an underlying sand/peat bedand then into a gravel layer. If the planter is a flowthroughstormwater planter, it has an impermeablebottom liner and an underdrain pipe to collect thetreated water and discharge it to the municipal stormdrain. Planters without an impermeable bottom liner(infiltration planters) will also require an underdrainwhen the underlying soils are less permeable than theplanter’s sand/peat layer.Photo Credit: City of PortlandSiting Considerations• Tributary Drainage area: Typically ≤ 1 acre.• Depth to Groundwater: > 10 ft from planter soil surface (onlyapplies to infiltration planter without underdrain).• Slope: Relatively flat.• Soils: For soil types C and D, use a flow-through planter with abottom liner and underdrain. For soil types A and B, aninfiltration-type planter may be used, but an underdrain may berequired if the underlying soils have lower permeability than theplanter’s sand/peat layer.• Setback: Flow-through planter is required if within 10 ft. ofbuilding foundation unless otherwise specified by localpermitting agency.POLLUTANT REMOVALEFFECTIVENESSSedimentNutrientsTrashMetals*Bacteria*Oil and GreaseOrganics*HighLowMediumHighMediumHighHigh*The following are target pollutants forSacramento area: copper; lead; mercury;pathogens; diazinon; and chlorpyrifos.Source: CASQA California StormwaterBMP Handbook, January 2003Vector Considerations• Potential for mosquitoes due to standing water will be greatly reduced or eliminated if the planteris properly designed, constructed, and maintained.Advantages• Relatively inexpensive when integrated into site landscaping.• Suitable for parking lots and sites with limited space.• Reduces peak flows during small storm events.• Attractive and relatively easy to maintain.Limitations• Not appropriate for industrial sites or locations where spills may occur, unless infiltration isprevented.• Not suitable for steeply sloping areas.General Maintenance Recommendations (Low to Moderate)• Periodically remove debris and sediment from planter.• Repair/replace vegetation as necessary to maintain full cover.• See table SP-2 for additional vegetation maintenance recommendation.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007SP-1