Volume 2-05, Chapter 3 - City of Wichita

Section 3.2.7 - Soakage Trench
3.2.7 Soakage Trench Primary Water Quality Facility
Description: Soakage trenches are a variation of
infiltration trenches. Soakage trenches drain through a
perforated pipe buried in gravel. They are used in
highly impervious areas where conditions do not allow
surface infiltration and where pollutant concentrations
in runoff are minimal (i.e. non-industrial rooftops).
They may also be used in conjunction with local
unregulated stormwater devices, such as residential
roof downspouts.
KEY CONSIDERATIONS
DESIGN CRITERIA:
• Intended for space-limited applications
• Like other infiltration devices, soakage trenches should not
be used for stormwater containing high sediment loads to
minimize clogging
ADVANTAGES / BENEFITS:
• Filtration provides pollutant removal capability
• Reservoir decreases peak flow rates
DISADVANTAGES / LIMITATIONS:
• Subsurface pipe considered an injection well and may
require special permit
MAINTENANCE REQUIREMENTS:
• Remove sediment and oil/grease from pre-treatment
devices, as well as overflow structures
• Mow grass filter strips as necessary
H
M
H
POLLUTANT REMOVAL
Total Suspended Solids
Nutrients – Total Phosphorus & Total Nitrogen
Metals – Cadmium, Copper, Lead & Zinc
STORMWATER MANAGEMENT
SUITABILITY
Water Quality Protection
Channel Protection
On-Site Flood Control
Downstream Flood Control
IMPLEMENTATION CONSIDERATIONS
M
H
H
Land Requirements
Relative Capital Costs
Maintenance Burden
Residential Subdivision Use: Yes
High Density/Ultra-Urban: Yes
Drainage Area: 5 acres max.
Soils: Pervious soils required
(0.5 in/hr or greater)
L=Low M=Moderate H=High
H
Pathogens – Coliform, Streptococci & E. Coli
Volume 2, Technical Guidance Page 3 - 93