PULELEHUA
Strategies for a liveable and connected community that can restore, connect and protect the watershed and sensitive reef ecosystems.
ABOUT THE SITE
The proposed Pulelehua development is situated in West Maui, mauka of Honoapiilani Highway between Kaanapali and Napili.
Pulelehua is also the Hawaiian name for the Kamehameha butterfly, which is endemic to Hawai'i and is the Hawaiian state insect.
According to the plans, the Pulelehua development is intended to be a “green residential and retail community designed for the local workforce as well as residents who wish to rent on a long-term basis.”
The proposed Pulelehua development is bordered by two drainage gulches, the Mahinahina Gulch and the smaller Pohaku-Ka'anapali Gulch. The Mahinahina Gulch has an existing sediment removal system, which ultimately drains through culverts and discharges directly into the ocean.
On the mauka side of the highway, West Maui is undergoing a transition from plantation agriculture to real estate development.
Sediment flows triggered by rainfall can activate accumulated sediment from fallow agricultural lands, existing dirt roads, and new development. These sediment flows impact the coral reefs in the lower watershed.
CHALLENGES ON SITE
THE NEED TO REDUCE ON-SITE RUNOFF FOR SEDIMENT CAPTURE
Coral reefs are declining due to global and local pressures. West Maui has significant sediment management challenges, including beach erosion; sediments washing onto the coral from legacy agriculture; and sediment disturbance and runoff attributable to new development projects. As a result, the health of the reefs is in significant decline and beaches face regular brown-water events.
ANALYSES OF FLOW DIRECTION AND FLOW PATHS
RECOMMENDATIONS
RECOMMENDED CHANGES
Overview of Recommended Changes (with corresponding points on plan or map)
Recommended Change 01:
Relocate certain buildings to maintain at least a 100’ buffer zone alongside Mahihina Gulch.
This will entail moving 2 housing units from the North side to the South side (with no net loss of units); switching the public park and commercial space on the south side; and relocating the south entry road slightly.
Recommended Change 02:
The moved housing unit sites will instead become community space (Gulch Park North)
Recommended Change 03:
For Gulch Park South, we suggest reconfiguring the entrance road, as well as placing the public park amenities next to the Mahinahina Gulch. Additional parking near the retail zone.
SUGGESTED REVISED MASTER PLAN
Rendered Master Plan of Pulelehua
New Improvement 01:
Buffer zones between roads, buildings, and the gulches are needed to maintain bank stability, limit erosion, reduce flooding, and manage sediment.
New Improvement 02:
Gulch Park North and Gulch Park South are on either side of the Mahinahina Gulch.
Gulch Park North will have a pavilion, BBQ area, and open space for gathering. Gulch Park North will be landscaped with native plants, community taro terraces, and other BMP sediment controls.
Gulch Park South will include the community athletic park that was already proposed in the Pulelehua plan, but realigned along the Mahinahina Gulch. It will also include buffer planting, a pedestrian and bike trail, interpretive signs, and traditional shade structures.
Gulch Park will supplement the sedimentation and stormwater retention capacity of the Gulch, and connect people with the watershed and beauty of the Gulch while reinforcing the connection between mauka and makai.
New Improvement 03:
Terrace Gardens will take use of the land within the contours of the development to provide stormwater retention, groundwater recharge, trapping of sediments, habitat for beneficial plants, and community space such as picnic tables and play areas for children.
Rain gardens "use plants, soil and mulch to capture dirty runoff and naturally break up pollutants. The result is less water pollution and an attractive, low-maintenance garden that also helps to reduce erosion." - Lahaina News, 21 Nov 2013
New Improvement 04:
Best Management Practices. The use of vetiver eyebrows and contour planting of vetiver to trap fine sediment, with complimentary planting of native species, is recommended as part of a mix of best management practices (BMPs) to stabilize soil and establish plants that are adapted to local conditions. Native species are also likely to need minimal maintenance after establishment. A suggested plant palette is available. We also recommend a bioswale between the development project and the main road.
New Improvement 05:
Education. Along the buffer zone and pavilions of Gulch Park, there can be interpretive signs to help people understand the water treatment functions of the Gulch (for example, when looking down on the sediment dam); raise awareness in the community that caring for the middle of the watershed helps to protect the reef from further degradation; teach about the butterflies; provide education about the importance of protecting the coral reefs from sediment and other pollution; and highlight the important steps that Pulelehua is taking to respect the reefs.
New Improvement 06:
Community resilience areas. Beneficial use of the area within the airport noise/building restriction areas, to include planting native trees, citrus trees, taro terraces, a community garden, and solar panels.
ON-SITE STORMWATER MANAGEMENT STRATEGIES
PLANTING MATRICES
The Pulelehua butterfly depends on the māmaki plant. Known as Pipturis albidus, māmaki is a perennial shrub or small tree that can grow to 15-feet tall and live for five years or longer. The leaves are fairly large and pretty and grow from 2 to 12-inches long. They also have attractive purple-red veins. Māmaki occurs on all of the major Hawaiian Islands. We recommend planting māmaki along the gulches to provide habitat for the Pulelehua butterfly.
Design Interventions
PHASE 1
As early as possible in the site development, put in place sediment control measures including theTerrace Gardens, bioswales along the road, the buffer zones along the gulches, and other BMPs, such as planting of vetiver.
PHASE 2
Construction of the homes, roads, additional bioswales for road switchbacks, community park, community gardens.
PHASE 3
Pedestrian bridge, installation of the solar farm.
