Contech Filterra® Bioretention Systems

Conditions of use 

All configuration options for the Filterra^® Bioretention Systems are approved for pollution reduction. Selection of a specific configuration is the responsibility of the project designer.

1. Use of Filterra Bioretention Systems does not exempt a project or site from required flow control requirements, operations and maintenance requirements, or other applicable requirements of the Stormwater Management Manual.
2. For use in the public right-of-way, the following conditions must be met: 
   • Units must meet City of Portland street design requirements, including but not limited to H-20 vehicle load rating, non-slip surface, and American with Disabilities Act tolerances specific to surface grates or vault lids.
   • The Operations & Maintenance Plan must call for an assessment during the two-year warranty period of project-specific maintenance and watering requirements, including frequency.
   • The following Zone 8 or Northwest region plants are allowed: 
     • Big-Pod Ceanothus - Ceanothus megacarpus  
     • Buttonbush - Cephalanthus occidentalis  
     • Cherry, Purpleleaf Sand - Prunus x cisterna
     • Coyote Bush - Baccharis pilularis ssp. Consanquinea
     • Euonymus, Chollipo - Euonymus japonicus 'Chollipo'
     • Euonymus, Winged (Burning Bush) - Alatus 'compactus'
     • Fringe Tree, White - Chionanthus virginicus
     • Hawthorn, Yedda 'Majestic Beauty' - Raphiolepis umbellata
     • Heavenly Bamboo - Nandina domestica (non-fruiting varieties)
     • Holly, Inkberry - Ilex glabra
     • Holly, Meserve - Ilex meservae
     • Holly, Winterberry - Ilex verticillata
     • Lilac, Dwarf - Syringa meyeri
     • Magnolia Star - Magnolia stellate
     • Willow, Japanese tree form - Salix integra 'Hakuro Nisjiki'
3. Contech-certified providers must be utilized for activation, inspection, and maintenance of the system. 

Project designer responsibilities

1. Ensuring that the conditions of use are met.
2. Ensuring that the project meets all applicable requirements of the City of Portland Stormwater Management Manual, such as the Stormwater Infiltration and Discharge Hierarchy, in order to use Filterra Bioretention Systems.
3. Ensuring that the design and installation of the units are appropriate for the project goals, site conditions, long-term maintenance requirements, and any other site-specific design requirements on private property or for use in the public right-of-way.
4. Sizing units to meet the current City of Portland Stormwater Management Manual presumptive design approach and pollution reduction requirements. The pollution reduction capacity is flow-based and assumes a treatment flow intensity of 0.19 inches per hour and a 0.90 runoff coefficient using the Rational Method with a treatment rate of 100 inches per hour. The treatment capacity for Filterra units are provided in Table 1.  

5. Each site plan must undergo Contech review before the City of Portland can approve the unit(s) for site installation. A letter that certifies that the project has been designed to manufacturer's specification must be submitted to the Bureau of Environmental Services prior to the appropriate design milestone. For public improvements, including public works permits, the letter must be submitted to the Bureau of Environmental Services prior to 60% plan review. For installation on private property, the letter must be submitted prior to building permit plan approval. The project designer is highly encouraged to work with Contech prior to the appropriate review milestone in order to maximize placement and performance of the unit(s).
6. If the project designer wants to use plants in public facilities not approved under the Conditions of Use, the project designer is required to get written approval from the City of Portland Environmental Services Revegetation Program and Contech prior to 90% plan review.
7. If the project designer wishes to vary from these conditions of approval, the project designer must use the Performance Design Approach.

Approval Conditions

1. The Bureau of Environmental Services may at any time suspend or revoke approval if the performance of the technology does not meet performance criteria, or if the performance criteria change due to the local, state, or federal pollution reduction standards.
2. If any changes, updates, or revisions have occurred to the Filterra^® Bioretention Systems, the applicant must obtain Washington State Department of Ecology Technology Assessment Protocol Technology General Use Level Designation certification and re-apply following submission guidelines in effect at the time of application.  

More information on the product can be found on the manufacturer's product website. 

Approved: July 2015 under the requirements of the 2014 Stormwater Management Manual.