#Creating a storm pcswmm series#

#Creating a storm pcswmm series#

Cells may be scattered throughout a subdivision a swale may run alongside the access road or a series of planter boxes may serve the road. The Ecology approval is meant to be used for I-2.5.6 Minimum Requirement #6: Runoff Treatment, where appropriate.Р”Р‡igure V-7.4.2 Example of a Bioretention PlanterР”В«ecause bioretention facilities use an imported soil mix that has a moderate design infiltration rate, they are best applied for small drainages, and near the source of the stormwater. Such systems are not considered LID BMPs and are not options for meeting the requirements of I-2.5.5 Minimum Requirement #5: On-site Stormwater Management. Note: Ecology has approved use of certain patented treatment systems that use specific, high rate media for treatment. (See Figure V-7.4.2 Example of a Bioretention Planter) These designs are often used in ultra-urban settings. Planters have an open bottom and allow infiltration to the subgrade. Planter boxes are completely impervious and include a bottom (must include an underdrain). (See Figure V-7.4.1a Typical Bioretention, Figure V-7.4.1b Typical Bioretention w/Underdrain, and Figure V-7.4.1c Typical Bioretention w/Liner (Not LID))Р”В«ioretention planters and planter boxes: Designed soil mix and a variety of plant material including trees, shrubs, grasses, and/or other herbaceous plants within a vertical walled container usually constructed from formed concrete, but could include other materials. Bioretention swales have relatively gentle side slopes and ponding depths that are typically 6 to 12 inches. (See Figure V-7.4.1a Typical Bioretention, Figure V-7.4.1b Typical Bioretention w/Underdrain, and Figure V-7.4.1c Typical Bioretention w/Liner (Not LID))Р”В«ioretention swales: Incorporate the same design features as bioretention cells however, bioretention swales are designed as part of a system that can convey stormwater when maximum ponding depth is exceeded. Bioretention cells may or may not have an underdrain and are not designed as a conveyance system. The following terminology is used in this manual:Р”В«ioretention cells: Shallow depressions with a designed planting soil mix and a variety of plant material, including trees, shrubs, grasses, and/or other herbaceous plants. The term, bioretention, is used to describe various designs using soil and plant complexes to manage stormwater. However, designs utilizing underdrains provide less flow control benefits.Р”В«ioretention areas are shallow landscaped depressions, with a designed soil mix and plants adapted to the local climate and soil moisture conditions, that receive stormwater from a contributing area. Where the native soils have low infiltration rates, underdrain systems can be installed and the facility used to filter pollutants and detain flows that exceed infiltration capacity of the surrounding soil.

Where the surrounding native soils have adequate infiltration rates, bioretention can help comply with flow control and treatment requirements. To provide effective removal of many stormwater pollutants, and provide reductions in stormwater runoff quantity and surface runoff flow rates. BMP T7.30: Bioretention Cells, Swales, and Planter Boxes