Volume 2-05, Chapter 3 - City of Wichita

Section 3.1 - Stormwater Management Controls Overview
Structural
Control
Alternative
TSS
Removal
Suitability
Site
Applicability
Implementation
Considerations
Physiographic
Factors/Soils
Special
Considerations
Other
Issues OK
Bioretention
Area
Stormwater
Wetland
Proprietary
Treatment
Gravity
Separator
Alum
Treatment
Green Roof X
Modular
Porous Paver
System
Porous
Pavement
X
High Cost
High Cost
High Cost
X
To provide additional pollutant removal capabilities in an attempt to better meet the target
removal, bioretention could be used to treat the parking lot and driveway runoff. The
bioretention will provide some TSS removal while improving the aesthetics of the site.
The site drainage system could be designed so the bioretention drains to the extended
detention micropool pond for additional treatment. If milder sloped turf areas are provided,
such as along the sides of the parking lots, vegetated swales and filters could be added to the
list of acceptable controls for additional treatment if not restricted by soil permeability.
Finally, modular porous pavers would be a good choice for the occasional overflow parking
that a church typically receives during weekly services. The low infiltration rate of site soils
could be overcome by adding an underdrain to the pavers.
3.1.4 On-Line Versus Off-Line Structural Controls
3.1.4.1 Introduction
Structural stormwater controls are designed to be either “on-line” or “off-line.” Figure 3-1
shows an example of an off-line sand filter and an on-line enhanced swale.
On-line facilities may provide treatment of all or part of the WQ v and may provide control of all
or part of the CP v . They may be designed to control flood flows; if not, they are designed to
receive and safely pass the entire range of storm flows up to the 100-year discharge.
Off-line facilities are designed to receive only a specified flow rate or volume through the use
of a flow regulator (i.e. diversion structure, flow splitter, etc). Flow regulators are typically
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Volume 2, Technical Guidance