CON/SPAN<sup>®</sup> Concrete Detention and Infiltration

CON/SPAN® Concrete Detention and Infiltration

CON/SPAN is a modular, precast concrete arch system designed to provide economical, large volume stormwater detention or infiltration below grade. CON/SPAN’s distinctive arch top and vertical side walls maximize storage volume while providing enhanced structural integrity.

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Large Volume Stormwater Storage

CON/SPAN is a modular precast system designed to provide economic, large volume stormwater detention or infiltration below grade.  CON/SPAN’s distinctive arch top and vertical side walls maximize storage volume and provide structural integrity. Combining the CON/SPAN arch unit with precast walls and cast-in-place foundations allows for an array of configurations to meet nearly any site need.

Construction of cast-in-place strip footings beneath CON/SPAN legs and end walls allow for a large open area in the center of each cell. These cells can be filled with crushed stone or granular material to allow for stormwater infiltration or recharge by percolating runoff through the granular material inside of the foundation.

CON/SPAN system provides efficient stormwater detention in a variety of footprints. Installation on a base slab foundation can be made watertight, which is ideal when dealing with high water table issues or subgrade soils sensitive to water infiltration.

COM/SPAN can be combined with the Stormwater Management StormFilter to provide high-volume stormwater treatment.

CON/SPAN Detention and Infiltration Features and Benefits



  1. Distinctive shape; arch top and vertical side walls
  1. Maximizes storage space; superior durability and structural integrity
  1. Full range of span & heights
  1. Versatile design capabilities
  1. Precast continuous foundation
  1. Ensures structural integrity and eliminates differential settlement
  1. Manufactured in quality controlled environment
  1. Superior quality over cast-in-place
  1. Base slab, strip, or pedestal wall foundations
  1. Foundation versatility

CON/SPAN Detention and Infiltration Installation

  • The CON/SPAN precast elements are three-sided arch units that offer rapid set-in place construction.
  • Systems are installed on top of cast-in-place concrete foundations.  Precast elements are set in a keyway that is cast into the foundation.
  • The system can also be installed on top of a pedestal wall foundation if additional vertical rise is required.

CON/SPAN Detention and Infiltration Maintenance

  • Manhole and other access openings can be located in the center of the units or along walls to allow for ladder access.
  • CON/SPAN can be equipped with a large opening between units that allow for maintenance equipment to be lowered into the system.

Design Your Own Detention or Infiltration System

The Contech DYODS is an exclusive online design tool to that allows users to quickly and easily design a detention or infiltration system. Just input your required storage volume to calculate the quantity of the material needed for your Contech CMP, CON/SPAN, or ChamberMaxx  system.


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Precast Systems for Stormwater Detention and Infiltration

Our CON/SPAN and Terre Arch concrete stormwater detention and infiltration solutions provide the versatility to accommodate any footprint needed. These patented precast structures are engineered to the highest degree – ensuring structural integrity.