Volume 2-05, Chapter 3 - City of Wichita

Section 3.2.4 - Grassed Channel
Grass Channels for Pretreatment
A number of other structural controls, including bioretention areas and infiltration trenches,
may utilize a grass channel as a pretreatment measure. The length of the grass channel
depends on the drainage area, land use, and channel slope. Table 3-6 provides sizing
guidance for grass channels for a 1 acre drainage area. The minimum grassed channel
length should be 20 feet.
Table 3-6 Bioretention Grass Channel Sizing Guidance When Used as Pretreatment
Parameter
Slope
(max = 4%)
Grass channel minimum length (feet)
assumes 2-foot wide bottom width
≤ 33% Impervious
Between 34% and
66% Impervious
≥ 67%
Impervious
≤ 2% > 2% ≤ 2% > 2% ≤ 2% > 2%
25 40 30 45 35 50
(Source: Claytor and Schueler, 1996)
3.2.4.4 Inspection and Maintenance Requirements
Regular inspection and maintenance is critical to the effective operation of stormwater
management facilities. An operation and maintenance plan is required and shall include:
1. “Covenants for Permanent Maintenance of Stormwater Management Facilities” (also
called the “Maintenance Covenants”). An example covenants document can be found in
Volume 3.
2. “Inspection Checklist and Maintenance Guidance” for each type of stormwater facility that
is located on the property. Templates for each stormwater management facility can be
found in Volume 3 of this manual. These templates can be amended slightly for use in
more customized O&M plans.
3. As-built drawings must accurately identify the location and layout of the facility, and clearly
identify reserves and access easements.
All stormwater management facilities must be maintained in accordance with the O&M Plan.
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Volume 2, Technical Guidance