The Makena Residential development is located above one of Hawaii’s ecological treasures, Makena Bay. The highest level of stormwater treatment was sought to protect this precious resource.
The engineer, Austin Tsutsumi & Associates, selected a treatment train concept that combines a number of stormwater BMP’s into one integrated system to both improve the quality and manage the quantity of runoff. The treatment train uses a Contech Stormwater Management StormFilter® followed by CON/SPAN® detention vaults, and an infiltration basin. Stormwater drains convey stormwater to a Contech
Stormwater Management StormFilter, a passive media filtration system that removes fine solids, soluble heavy metals, oil and total nutrients from urban runoff. The site called for four StormFilter vaults and a total of 30 filter cartridges.
Filtered water is then conveyed to two 2 Con/SPAN detention vaults used to reduce the quantity of stormwater runoff flowing into the retention basin by temporarily storing the runoff and releasing it slowly over time. CON/SPAN is an economical, modular precast system designed to provide economic concrete below grade stormwater detention.
Lastly, the filtered water flows to the retention basin where it infiltrates the soil.
This system, the first of its kind installed in Hawaii, is now favored by the LID regulations recently adopted by the City and County of Honolulu. The project is being certified under the Leadership n Energy and Environmental Design (LEED) Green Building Rating System.