Model drainage system for coastal development on Maui
LOW IMPACT DEVELOPMENT
The Mākena Golf & Beach Club, with the expert direction of leading ecological engineering firm, EcoSolutions, is proud to offer the first completely Low Impact Development (LID) in Maui and one of the most comprehensive in the State of Hawaii.
LID was selected as best management practices (BMP) to provide both retention and treatment of stormwater runoff. LID is an approach to development (or re-development) that mimics the pre-development hydrology and uses ecological engineering to remove pollutants in the stormwater, so it can be re-used onsite and/or to replenish groundwater supplies.
The project uses ecological design techniques such as Green Stormwater Infrastructure (GSI). Some of the GSI techniques used on this project include permeable pavement, vegetated swales, and bioretention systems (also known as rain gardens).
STORMWATER MANAGEMENT PLAN
LOW IMPACT DEVELOPMENT (LID)
A comprehensive drainage plan with Low-Impact Development (LIDs) techniques will be implemented as part of the project. Kāʻeo was designed to address a 100-year, one-hour storm event, which the equivalent to three inches of rainfall per hour, which will exceed the 50-year, one-hour storm event requirements set forth by the County of Maui, Department of Public Works.
This project includes a LID stormwater management plan consisting of Green Stormwater Infrastructure (GSI) techniques including permeable pavement, vegetative swales, and bioretention (rain gardens). This plan has been viewed as a "Model for Maui" by engineers and water quality experts. Pollutants that are commonly in stormwater and cause damage to nearshore environments (bacteria, nutrients, sediment, heavy metals, etc) will be removed through biofiltration, before the clean water infiltrates into the ground. This environmentally friendly stormwater treatment methodology is championed by the Environmental Protection Agency, The Sierra Club, The Nature Conservancy, U.S. Green Building Council, the American Institute of Architects, the Urban Land Institute, and many other local, state and federal environmental protection groups. Most importantly, it will protect the nearshore environment and improve marine water quality.
This project will showcase the first "green streets" concept on Maui. Common roadways will be constructed of permeable materials (e.g., permeable asphalt, concrete, or interlocking concrete pavers). Adjacent vegetative swales will be used to direct surface runoff into bioretention features (rain gardens) distributed across the site. These systems work as a water quality "treatment train," retaining large storm events while also removing harmful pollutants. The landscape plan will utilize drought-tolerant coastal and native plants to reduce water consumption and restore the natural habitat.
Concept Renderings of Future Green Streets
CONSTRUCTION RUNOFF MANAGEMENT AND MONITORING
The contractor is dedicated to minimizing construction runoff on this project. The BMPs they have in place are robust and prepared to handle a heavy rain event. They will be inspecting all BMPs, discharge locations, and piles of soil/rock prior to a rain event and as part of their daily construction site routine. A regular inspection of BMPs will catch any issues prior to an unexpected rain event.
As an additional safeguard, a third-party will be conducting random quarterly inspections of the BMPs on the construction site, per the SMA requirements for the project. This helps ensure good housekeeping.
Lastly, monitoring of near-shore water will be occurring during construction. A monitoring buoy has been installed in the ocean directly makai of the Kāʻeo project area, and collects turbidity data in real-time. The automated probes will send a notification if the turbidity levels exceed a pre-programmed threshold. If this occurs, the developer and contractor will be notified so that any unintentional malfunctions in BMPs may be immediately addressed. The turbidity data will be reported out monthly.