News Article


StormTech® - Open Bottom Stream & Wetland Crossing Structure

Utilizing open bottomed chambers as stream and wetland crossing structures is an excellent, cost-effective alternative to closed bottom structures. The open bottom allows for less disruption to the natural substrates within the streambed, as it is not necessary to embed the invert within the channel.

The open bottom allows for unimpeded stream fl ow, minimizing issues of stream disruption and eliminating the corrosive effects on water quality that can be a result of designing with CMP.

StormTech® chambers are ideal for low velocity waterways. The large interior bottom widths of up to 80” make it easier to maintain streambed continuity and allows for easy placement of the correct bedding materials for the crossing’s hydraulic design.

Maintaining the existing streambed also promotes stream and wetland continuity, normalizes transport, and preserves the natural fl ow regime. A natural streambed within a crossing is ideal for aquatic organism and amphibian passage, minimizing habitat fragmentation. By creating a wide open and well-illuminated crossing, critters and other wildlife are able to safely pass underneath roadways.


With safety, durability and longevity in mind, StormTech® chambers are engineered and manufactured to conform to ASTM F2418, ASTM F2922 and ASTM F2787 standards. They also exceed AASHTO 12.12 LRFD requirements for both live load and dead loads that require a 2-1 safety factor. The chambers are made of polypropylene resin eliminating corrosion which can lead to structural failure and the need for replacement


  • Promotes stream and wetland continuity
  • Provides unimpeded stream flow
  • Normalizes stream transport
  • Minimizes habitat fragmentation
  • Maintains natural streambed substrates • Ideal for aquatic organism & amphibian passage
  • Eliminates embedded culvert invert
  • Reduces likelihood of plunging jet scour hole formation, which create fish breaks


Highway construction, timber harvesting, agricultural conversion, urban/ residential development, and other factors have contributed to habitat loss and fragmentation over time. These issues threaten all species that need to cross roads to meet their biological needs. Utilizing open bottom chambers as underpasses or tunnels can assist with creating critter and wildlife crossings, safely linking habitat areas while enhancing new development.