Volume 2-05, Chapter 3 - City of Wichita

Section 3.1 - Stormwater Management Controls Overview
3.1.6 Using Structural Stormwater Controls in Series
3.1.6.1 Stormwater Treatment Trains
The minimum stormwater management standards are an integrated planning and design
approach whose components work together to limit the adverse impacts of development on
downstream waters and riparian areas. This approach is sometimes called a stormwater
“treatment train.” When considered comprehensively, a treatment train consists of all the
design concepts and nonstructural and structural controls that work to attain water quality and
quantity goals. This is illustrated in Figure 3-6.
Runoff & Load
Generation
(Source Control)
Pretreatment
Control
Standard
Treatment and/or
Quantity Control
Figure 3-6 Generalized Stormwater Treatment Train
Runoff and Load Generation: The initial part of the “train” is located at the source of runoff
and pollutant load generation, and consists of pollution prevention practices and optional
“Preferred Site Design” practices that reduce runoff and stormwater pollutants.
Pretreatment: The next step in the treatment train consists of pretreatment measures. These
measures typically do not provide sufficient pollutant removal to meet the overall TSS target
reduction goal, but do provide calculable water quality benefits that may be applied towards
meeting the WQ v treatment requirement. In addition, pre-treatment may reduce maintenance
and/or improve the performance of downstream facilities. These measures include:
• Structural controls that achieve less than the overall TSS target removal rate, but provide
pretreatment for sources such as hotspots.
• Pretreatment facilities such as sediment forebays.
Standard Treatment and/or Quantity Control: The last step is standard water quality treatment
and/or quantity (channel protection and flood) control. This is achieved through the use of
structural controls to achieve overall water quality and quantity goals.
3.1.6.2 Use of Multiple Structural Controls in Series
Many combinations of structural controls may be used for a site. The following are
descriptions of some examples of how controls and other practices may be combined to
achieve the goals of the integrated design approach.
• Stormwater ponds are often used to achieve overall target TSS removal as well as
channel protection and flood control, thus meeting all of the requirements of the integrated
site design approach in a single facility.
Page 3 - 20
Volume 2, Technical Guidance