Filterra® Bioretention Systems Approved by Washington State Department of Ecology for General Use Level Designation

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The Washington State Department of Ecology has Approved Filterra® for General Use Level Designation

Filterra is an advanced high flow rate bioretention system for stormwater treatment. The Washington State Department of Ecology has approved the sizing of the Filterra units as listed below.

Table 1: WWHM Sizing for Basic Treatment - TSS, Oil/Grease and Phosphorous* Treatment - Western Washington Only

Available Filterra Box Sizes (feet)	Approximate Contributing Drainage Area (acres)
4 x 4	0.195
4 x 6 or 6 x 4	0.285
4 x 8 or 8 x 4	0.375
6 x 6	0.430
6 x 8 or 8 x 6	0.575
6 x 10 or 10 x 6	0.720
6 x 12 or 12 x 6	0.865

*Conditional use only.

Sizing table intended for planning level use. The design engineer must use the latest version of WWHM to calculate the appopriately sized facility. (91% Stormwater Filtered)

Table 2: WWHM Sizing for Enhanced Treatment - Dissolved Metals - Western Washington Only

Available Filterra Box Sizes (feet)	Approximate Contributing Drainage Area (acres)
4 x 4	0.140
4 x 6 or 6 x 4	0.210
4 x 8 or 8 x 4	0.275
6 x 6	0.310
6 x 8 or 8 x 6	0.415
6 x 10 or 10 x 6	0.520
6 x 12 or 12 x 6	0.630

Sizing table intended for planning level use. The design engineer must use the latest version of WWHM to calculate the appopriately sized facility. (91% Stormwater Filtered)

For sizing in other areas of Washington State please contact us.

Washington Study Findings of Fact for Test Sites

TSS removal was >80% for concentrations >20mg/l
Dissolved Zinc removal >54%
Dissolved Copper removal >40%
Total Petroleum Hydrocarbon removal 93%
Infiltration rates up to 133 in/hr were observed

An engineer's Design Assistance Kit is available by e-mail. Your DAKit includes Sizing Made Easy, Project Information Form, specifications, detailed drawings, placement scenarios, etc.

For more details about the approval contact us or visit the Washington State Department of Ecology website.

Filterra

A Growing Idea In Stormwater Filtration

Products

The Washington State Department of Ecology has Approved Filterra® for General Use Level Designation

Table 1: WWHM Sizing for Basic Treatment - TSS, Oil/Grease and Phosphorous* Treatment - Western Washington Only

Table 2: WWHM Sizing for Enhanced Treatment - Dissolved Metals - Western Washington Only

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