Honolulu Vegetated Bio-Filter Requirements

This Honolulu Ordinance requires that engineered vegetated bio-filters have a flat base, ponding depth ≤12 inches, 2–4 inches of mulch, and 2–4 feet of planting soil with permeability ≥1 foot/day to ensure drainage within 48 hours. Non-vegetated media can be substituted. Proprietary systems must be TAPE-certified by Washington State for treatment of the relevant pollutants (e.g., dissolved metals, phosphorus, or oil).