Modular Wetlands® Linear Stormwater Biofiltration

Modular Wetlands® Linear Stormwater Biofiltration

Achieve superior stormwater quality with our biofiltration system. Explore our Modular Wetlands Linear system for efficient biofiltration and biofiltration basins.

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Modular Wetlands® Linear - Stormwater Biofiltration

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

Features Benefits
Pretreatment chamber Enhanced pollutant removal, faster maintenance 

Horizontal flow biofiltration

Greater filter surface area

Performance verified by both the WA DOE and NJ DEP

Superior pollutant capture with confidence

Built-in high-flow bypass

Eliminates flooding and the need for a separate bypass structure

Available in multiple configurations and sizes

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.

Pollutant Median Removal Efficiency    
Total Suspended Solids (TSS) 85%    
Total Phosphorus (TP) 64%    
Ortho Phosphorus (OP) 67%    
Total Nitrogen (TN) 45%    
Total Copper (TCu) 50%    
Dissolved Copper 38%    
Total Zinc (TZn) 69%    
Dissolved Zinc 56%    
Total Petroleum Hydrocarbons 95%    
Source: TAPE Filed Study 2012/2013

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) 

Technical information for this product is located in the technical guide’s section. 

View Technical Information
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.

The Contech Advantage

Agency/Regulatory Guidance

Our team is ready to provide you with expert advice and assistance on local regulatory requirements, resulting in faster approvals.


Solution Development

Our engineers can review your requirements, weigh all options, and recommend the optimal solution to integrate with your site designs.

Technical Expertise

Our engineers can assist by providing product specific engineering calculations such as hydraulics, buoyancy, foundation reactions, and unit sizing.

Cost Estimates

We can quickly provide engineer’s cost
estimates to assist with your solution
selection process.

Site Specific Drawings

Our engineers can provide site-specific drawings for proposals, project meetings, and submittals, helping you be more efficient with your time.

On-site Assistance

Contractors know time is money, so we provide preconstruction meetings, delivery coordination, and on-site installation support to ensure a timely, smooth installation.