Contech Engineered Solutions -Modular Wetlands® Linear Stormwater Bioretention


The Modular Wetlands® Linear is the only stormwater bioretention system to utilize patented horizontal flow, allowing for a smaller footprint, higher treatment capacity, and design versatility.

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Contech Engineered Solutions
9100 Centre Pointe Drive
West Chester, OH 45069
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Modular Wetlands® Linear Stormwater Bioretention

The Modular Wetlands® Linear is the only stormwater bioretention system to utilize patented horizontal flow, allowing for a smaller footprint, higher treatment capacity, and design versatility.

Modular Wetlands® Linear - Stormwater Bioretention

The Modular Wetlands Linear is the only biofiltration system to utilize patented horizontal flow, allowing for a smaller footprint, higher treatment capacity, and design versatility. It is also the only biofiltration system that can routinely be installed downstream of storage for additional volume control and treatment.

With numerous regulatory approvals, the system’s aesthetic appeal and superior pollutant removal make it the ideal solution for a wide range of stormwater applications, including urban development projects, commercial parking lots, residential streets, mixed-use developments, streetscapes, and more.

  • Stormwater enters the pretreatment chamber where total suspended solids settle, and trash and debris are contained within the chamber. Stormwater then travels through the pre-filter boxes that provide additional treatment.
  • As water enters the biofiltration chamber, it fills the void space in the chamber’s perimeter. Horizontal forces push the water inward through the biofiltration media, where nutrients and metals are captured. The water then enters the drainpipe to be discharged.
  • The specially designed vertical drainpipe and orifice control plate control the flow of water through the media to a level lower than the media’s capacity, ensuring media effectiveness. The water then enters the horizontal drainpipe to be discharged.
  • During peak flows, an internal weir in the side-by-side configuration allows high flows to bypass treatment, eliminating flooding and the need for a separate bypass structure. Bypass is not provided in the end-to-end configuration.
Modular Wetlands Linear Features and Benefits


Pretreatment chamber

Horizontal flow biofiltration

Performance verified by both the WA DOE and NJ DEP

Built-in high-flow bypass

Available in multiple configurations and sizes


Enhanced pollutant removal, faster maintenance

Greater filter surface area

Superior pollutant capture with confidence

Eliminates flooding and the need for a separate bypass structure

Flexibility to meet site-specific needs

Pollutant Removal Performance

The Modular Wetlands Linear continues to outperform other treatment methods with superior pollutant removal for TSS, heavy metals, nutrients, and hydrocarbons. The Modular Wetlands® Linear is field-tested on numerous sites across the country and is proven to effectively remove pollutants through a combination of physical, chemical, and biological filtration processes.


Total Suspended Solids (TSS)

Total Phosphorus (TP)

Ortho Phosphorus (OP)

Total Nitrogen (TN)

Total Copper (TCu)

Dissolved Copper

Total Zinc (TZn)

Dissolved Zinc

Total Petroleum Hydrocarbons

Median Removal Efficiency










Some jurisdictions recognize higher rates - contact your Contech Stormwater Consultant for performance expectations.

Select Modular Wetlands Linear Approvals

The Modular Wetlands Linear has been evaluated by some of the most stringent stormwater technology evaluation organizations in North America, including, but limited to:

  • Washington Department of Ecology (GULD) - Basic, Enhanced, Phosphorus
  • California Water Resources Control Board, Full Capture Certification
  • New Jersey Department of Environmental Protection (NJDEP)
  • Virginia Department of Environmental Quality (VA DEQ)
  • Maryland Department of the Environment - Environmental Site Design (ESD)
  • Texas Commission on Environmental Quality (TCEQ)
  • Rhode Island Department of Environmental Management (RIDEM)
  • Atlanta, GA Regional Commission
  • City of Portland, Oregon Bureau of Environmental Services
  • Canadian ISO 14034 Environmental Management - Environmental Technology Verified (ETV)
  • Curb Inlet
  • Vault
  • Downspout
The Modular Wetlands Linear is a self-contained treatment train. Maintenance requirements for the unit consist of five simple steps that can be completed using a vacuum truck. The system can also be cleaned by hand.
  • Remove trash from the screening device
  • Remove the sediment from the separation chamber
  • Periodically replace the pretreatment cartridge filter media
  • Replace the drain-down media
  • Trim vegetation (if needed)

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Curb Inlet

The Curb Inlet configuration accepts sheet flow through a curb opening and is commonly used along roadways and parking lots. It can be used in sump or flow-by conditions.


The Vault configuration can be used in end-of-the-line installations. Another benefit of the “pipe-in” design is the ability to install the system downstream of underground detention systems to meet water quality volume requirements, or for traffic-rated designs (no plants).


The Downspout configuration is designed to accept a vertical downspout pipe from rooftop and podium areas. Some models have the option of utilizing an internal bypass, simplifying the overall design. The system can be installed as a raised planter, and the exterior can be stuccoed or covered with other finishes to match the look of adjacent buildings.