Volume 2-05, Chapter 3 - City of Wichita

Section 3.2.8 - Surface Sand Filter
• Compute V f = water volume within filter bed/gravel/pipe = A f * d f * n
Where: n = porosity = 0.4 for most applications
• Compute V f-temp = temporary storage volume above the filter bed = 2 * h f * A f
• Compute V s = volume within sediment chamber = V min - V f - V f-temp
• Compute h s = height in sedimentation chamber = V s /A s
• Ensure h s and h f fit available head and other dimensions still fit; change as
necessary in design iterations until all site dimensions fit.
• Size orifice from sediment chamber to filter chamber to release V s within 24-
hours at average release rate with 0.5 h s as average head.
Step 9
Step 10
Design inlets, pretreatment facilities, underdrain system, and outlet structures
See Chapter 5 for more details.
Compute overflow weir sizes
• Size overflow weir at elevation h s in sedimentation chamber (above perforated
stand pipe) to handle surcharge of flow through filter system from storms
producing more than WQ v design event.
• Plan inlet protection for overflow from sedimentation chamber and size
overflow weir at elevation h f in filtration chamber (above perforated stand pipe)
to handle surcharge of flow through filter system from storms producing more
than WQ v design event.
3.2.8.7 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 layout and location of the facility, and also
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