Based on Kailua’s existing stormwater collection system, water cleansing structures of three diminishing sizes are proposed. All share the goal of filtering, by various means, stormwater which would otherwise flow directly into the Hamakua Wetlands.
1) Coconut Grove Outfalls – Coconut Grove currently has four Stormwater Outfalls along the Kailua side of the levee. Each is nicely suited for a Bio-Retention Pond. (The end of the canal itself could be designed as a fifth Pond.) Coconut Grove’s existing storm drains and collection network would continue to direct water to these refitted Ponds. Litter is trapped and stormwater cleaned as it flows through the Pond Systems. — Coconut Grove’s current storm drains are not well suited for Curbline Planter Filtration (see below.) It’s fortunate these Pond locations already exist.
2) Wetland Bio-Remediation Sites –
3) Curbline Planter/Bio-Filters –
Raingarden Plant Trials System – Much work has been done on the mainland to discover which plant species function to clean water most effectively in their more temperate raingardens, bio-swales, retention ponds, etc. Pictured below is a monitoring set-up which could be used to compare various plant species in our Hawaiian climate. It provides a) the ability to assess different species’ side-by-side ability to cleanse a particular type of polluted water, or b) how well a single species thrives and functions when exposed to waters of differing side-by-side pollution loads.
