20200348 Ver 1_Appendix F - Filterra - Stormwater Biofiltration Info & Sizing_20200306

FILTERRA SIZING CALCULATIONS
The Filterra system is a product from Contech that utilizes biofiltration to remove nutrients and
pollution from surface runoff. A key component in the software used for sizing the system is the
percentage of impervious area within the drainage area studied. Based on the information available,
sizing the Filterra structure to reduce nutrient loading from turf areas requires converting a runoff from
the grass area to a proportional amount of impervious area. Using the “rough” as the limit of the
concentration for the fertilizer application as the study area. A ratio for the surfaces is determined by
using the ‘C’ factor in the rational formula (Q=CIA). The ‘C’ for asphalt is 0.95 and a ‘C’ factor of 0.15 for
grass in sandy loam soil, the resulting ratio is 0.15/0.95 = 15.8%. This ratio is a percentage to convert a
portion of the study area from an actual “grass” surface to a theoretical “impervious” surface area. The
ratio is multiplied by the total study area to determine an equivalent amount of impervious surface area
within the study area for use in the design software.

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Description
How Filterra Works
Stormwater runoff enters the Filterra system through a curb-inlet opening or pipe and flows through a specially designed
filter media mixture contained in a landscaped concrete container. The filter media captures and immobilizes pollutants;
those pollutants are then decomposed, volatilized and incorporated into the biomass of the Filterra system’s
micro/macro fauna and flora. Stormwater runoff flows through the media and into an underdrain system at the bottom
of the container, where the treated water is discharged.
Filterra Features and Benefits
Features Benefits
High media flow rate (up to 140" per hour)Reduced footprint compared with
traditional bioretention
Technical Info Configurations Brochures
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Features Benefits
Third party field testing confirmed that Filterra meets state regulator y requirements for
pollutant removal under TAPE and TARP testing
Regulator y Compliance
Filterra offers the most cost effective stormwater treatment system featuring low cost, easy
installation and simple maintenance
Value
Landscaping enhances the appearance of your site making it more attractive while
removing pollutants
Adds aesthetic appeal to your site
Available in multiple configurations and sizes Flexibility to meet site-specific nee
No confined space access, and the first year of maintenance is included with the purchase
of every system
Simple and easy maintenance
Configurations
Inline
Offline
Peak Diversion
Bioscape Vault
Filterra Bioscape
Custom Configurations
Filterra Media – Proven Pollutant Removal
 At the heart of all Filterra systems is Filterra engineered media; a specified gradation of washed aggregate and organic
material homogeneously blended under strict quality controlled conditions. Using data from studies conducted by the
University of Virginia, the filter media has been optimized to operate under high flow rates (up to 140 inches/hour) while
maintaining pollutant removal performance. Filterra media is tested for hydraulic functionality, fertility, and particle size
distribution to ensure uniform performance.
MEASURED POLLUTANT REMOVAL PERFORMANCE
Pollutant Median Removal
Efficiency
Median Effluent
Concentration (mg /L)
Third Party Reference Studies
Total Suspended Solids 86%3.3 UVA 2006, Herrera 2009, Herrera 2014
State 2015
Total Phosphorus
(TAPE)
70%0.05 Herrera 2014, NC State 2015
Total Nitrogen 34%0.54 NC State 2015
Total Copper 55%0.004 UVA 2006, Herrera 2009
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Dissolved Copper 43%0.003 Herrera 2009
Total Zinc 56%0.04 UVA 2006, Herrera 2009, NC State 201
Dissolved Zinc 54%0.1 Herrera 2009
Total Petroleum
Hydrocarbons
87%0.71 Herrera 2009
Information above is based on results from third party field studies following industry recognized protocols such as TAPE
and TARP. Relevant studies are noted for each pollutant, and corresponding data was aggregated to provide realistic and
repeatable performance expectations.
Some jurisdictions recognize higher removal rates - see your Contech Stormwater Consultant for performance
expectations.
Select Filterra Approvals
Washington Department of Ecolog y (GULD) – Basic, Enhanced,Phosphorus, and oil
New Jersey Department of Environmental Protection (NJDEP)
Maine Department of Environmental Protection
Maryland Department of the Environment - Environmental Site Design (ESD)
North Carolina Department of Environmental Quality (NC DEQ)
Texas Commission on Environmental Quality
City of Portland, Oregon Bureau of Environmental Ser vices
Virginia Department of Environmental Quality
Sacramento Stormwater Quality Partnership (SSQP) 
Applications
Low Impact Development, Green Infrastructure, and Environmental Site Design
High pollutant removal requirements
New construction and urban retrofits
Pretreatment for above-ground or shallow below-ground storage
Shallow, decentralized treatment
Installation and Maintenance
We make it easy for you...
Vegetation selection guidance based on your climate zone.
On-site planting and activation included with ever y system.
The first year of maintenance is included with the purchase of ever y system.
Ongoing maintenance is simple.
Clean biofiltration bay with simple landscape tools (rake and shovel).
No confined space entry required.
Ever ything can be accessed from the surface.
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