Building Green in the Virgin Islands
Design and Construction Guidelines
Development and construction activities have the potential to cause extensive and even catastrophic impacts on the surrounding vegetation, adjacent properties and the nearby, downstream marine communities. Loss of plant cover that stabilizes soils, alterations to natural drainage channels and runoff laden with sediment have gross negative impacts on the natural environment.
With careful and comprehensive planning and appropriate construction methods these negative impacts can be reduced or even eliminated. These guidelines, drawn up by IGBA professionals, outline steps to be taken to achieve this result.
Section 1 Subdivisions and Roadways
- Site Design Considerations
- Topographic Features & Drainage Guts
- Surface & Storm Water Management
- Vehicle Access & Parking Areas
- Limiting Site Disturbance
- Land Clearing & Native Plant Conservation
- Responsible Site Excavation
- Paving, Drainage & Storm Water Structures
- Landscaping & Soil Stabilization
- Open Space, Green Belts & Wildlife Habitat
- Long-term Maintenance
Section 2 Construction and Buildings
- Site Planning & Design
- Building Structure
- Water Management
- Energy Conservation & Management
- Waste Minimization & Recycling
- Light Pollution
- Visual Pollution
- Landscaping, Green Belts & Native/Natural Vegetation
Site Design Considerations
· Knowledgeable planning and site design can help avoid creating drainage problems onsite and downstream on a neighboring property. Constructing with the natural contours in mind can cost less and create fewer problems.
· Major subdivision and roadway planning should emphasize larger lot sizes, smaller cleared areas and cluster type development to reduce impacts.
· Developments within national park boundaries, or adjacent to national park lands, should be respectful of the park and establish as low-profile presence as possible.
· Efforts should ensure that visual aesthetics are maintained in harmony with the surrounding community. Subdivision style and layout should blend to preserve the existing viewshed and visual privacy of adjacent properties.
· In areas where clearing and excavation will take place, solid, effective erosion control measures must be installed prior to any site disturbance to reduce sediment deposition. Silt fencesshould be well constructed, dug-in and installed prior to any mechanical excavation work or vegetation clearing. · Attention should be focused on the type and placementof external lighting to avoid negative impacts on residents and on wildlife. Sea turtle nesting behavior, in particular, is adversely affected by coastal lighting.
Topographic Features& Drainage Guts
· The major impacts of subdivision and road construction result from poor land development practices leading to ineffective storm water management and subsequent erosion. St. John and many other Caribbean islands, have very steep topography, creating complex natural drainage guts that carry storm water to the sea.
· Crossing a gut with a road or constructing a building adjacent to a gut, alters the natural path of storm water, creating drainage and erosion problems.
· Proper subdivision and roadway planning begins with understanding the existing topography and drainage system and designing improvements that limit alterations.
Surface & Storm Water Management
· Water flows downhill, across and through the landscape until it reaches low points or guts that collect and carry large volumes to the coast. Existing drainage pathways should be maintained in their original form as much as possible.
· Road cuts and building site work change natural drainage patterns and create new pathways. To reduce erosion and sedimentation problems, avoid altering or crossing drainage guts and when it is unavoidable, culverts must be used to allow storm water to follow its natural course.
Vehicle Access & Parking Areas
· Driveways and parking areas generally require excavation to some degree. Driveways and parking areas should be kept to a minimum to reduce erosion potential.
· In cleared areas, berms and swales should be created to contain runoff. Driveways and parking areas should be surfaced (pavement, permeable pavers or gravel) as soon as possible and equipped with drainage structures that reduce runoff velocity.
Limiting Site Disturbance
· Clearing of vegetation cover should be limited to the minimum area necessary to complete construction so as to create minimum erosion and runoff. This clearing should be limited to the building footprint, sewage disposal and driveway areas.
· All trees should be preserved if at all possible or replaced with appropriate native trees and shrubs. Hand clearing of small areas is preferable to machine clearing as it produces less disturbance.
Land Clearing & Native Plant Conservation
· Brush and waste vegetation should be kept to a minimum and can be used on the perimeter of the site to buffer the adjacent ground from soil loss.
· Brush should be composted or recycled onsite. Every effort should be made to retain native vegetation species as they are better adapted to the climate and soils and generally require less water.
· Native vegetation greenbelts should be kept along all roadways and an effort should be made to create greenbelts and open space areas within the development.
· Plant or mulch bare soils to prevent soil losses.
Responsible Site Excavation
· The width and height of excavations for roads, driveways and buildings should be minimized. All erosion control measures must be in place prior to the start of excavation.
· Proposed grading should not alter or impair existing surface drainage pathways, act as a source of sedimentation to other adjacent properties environments or affect other drainage control structures.
· Excavation should be done in stages to allow for re-vegetation, paving and the building of drainage structures. As soon as possible, excavation cuts should be stabilized with retaining walls, mulched or planted.
· Material staging and storage should be carefully considered and confined on the development site. Construction waste should be removed regularly to appropriate landfills or transfer stations.
Paving, Drainage & Storm Water Structures
· Steps should be taken to manage and control the quantity of polluted water that drains from the development site during heavy rains and tropical storms.
· Efforts should be made to collect and reuse rain/storm water from paved areas within the development where possible on greenbelt and open space lands.
· Permeable surface materials should be considered for use in parking and roadway area. Paved surfaces, retaining walls and drainage structures should be installed prior to, or immediately after excavation.
Landscaping& Soil Stabilization
· As much as possible, native vegetation should be conserved. Native trees and shrubs should be used to re-vegetate and stabilize slopes and cut banks.
· Bare soils should be mulched or re-seeded as soon as possible.
Open Space, Green Belts & Wildlife Habitat
· Subdivisions and roadways should be limited in size and disturbance. Cluster type developments should be considered in order to leave as much land undisturbed as possible.
· Roadways should be built as narrow as safety will allow to reduce disturbance and erosion potential.
· Open space and greenbelts can act as valuable wildlife habitat. Create large core areas of habitat that can support a diversity of plant and animal communities.
· Roadways, drainage structures and other pollution controls require periodic maintenance to function properly. Develop a plan for maintenance and a means of completing the work on a regular basis.
Site Planning & Design
· Design the site to achieve the functional requirements of the development with minimum site disturbance and maximum environmental protection
· Make every effort to retain native/natural vegetation on the site by clearly delineating the areas of the property to be left undisturbed.
· Utilize building setbacks as green belt areas along roads and property lines.
· Develop surfaced onsite parking areas to minimize runoff and eliminate on road parking.
· Develop an Excavation, Storm Water Drainage and Erosion Control Plan to minimize site runoff and pollution of the environment. Maximize collection and retention of storm water on the property through the use of berms, swales, settlement terraces and landscape irrigation. Systems should be designed to handle very heavy rainfall.
· Use cleared brush for down slope diversion berms. Compost on site, rather than burn the remaining cleared brush.
· Design the building to be responsive to and reflective of tropical architectural design considerations, including trade winds and sun paths.
· Use renewable, recyclable, local, sustainably produced, non-toxic materials.
· Design for protection against hurricanes and earthquakes.
· Use Caribbean (vernacular) architectural design elements.
· Design for lifecycle cost considerations with quality, low maintenance materials and systems.
· Develop a water management and conservation plan for each building or structure.
· Use an ecologically balanced Onsite Sewage Disposal System (where not connected to a municipal sewer system).
· Develop rainwater and gray water collection systems to maximize retention onsite and minimize runoff.
· Use non-potable (gray) water for landscape irrigation.
Energy Conservation & Management
· Design an energy system that maximizes the use of renewable energy.
· Use solar hot water heating.
· Include photovoltaic (solar) and wind energy systems for auxiliary electric power where practical.
· Minimize the need for air conditioning by using a building orientation that takes maximum advantage of trade winds and minimizes heat gain within the structure from solar radiation.
· Design energy efficient, sealed, insulated building envelopes for climate-controlled spaces, when air conditioning is required.
Waste Minimization & Recycling
· Develop a process to minimize waste during the construction phase and on-going building operations.
· Design for efficient use of materials during construction.
· Reuse onsite fill material and stone for landscaping.
· Salvage and reuse construction materials when remodeling.
· Design space for onsite composting of kitchen and garden waste.
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· Design an exterior lighting system that minimizes the amount of ambient light visible from outside the property.
· Eliminate outwardly shining lights on buildings, patios and decks.
· Use downward facing light fixtures on decks, pools and patios.
· Use ground level fixtures for driveways, paths and landscape lighting.
· Developments within national park boundaries, or adjacent to national park lands, should be respectful of the park and construct low profile structures and “blend in” to the extent possible.
· Retain vistas on owners property and respect adjacent property vistas.
· Preserve the visual privacy of the property, adjacent properties and those across a valley.
· Create landscape screens to hide on-site parking areas from structures and roads.
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Landscaping, Green Belts & Native/Natural Vegetation
· The preservation of the existing natural vegetation of a site is the simplest and most cost effective form of landscaping. This vegetation is already well established onsite and will survive in our extreme environment without constant irrigation.
· Landscape with native plants that will survive in a dry climate wherever practical.
· Carefully consider and plan for the effective use of imported exotic tropical vegetation which is not self-sustaining (requiring continuous watering), may be invasive, crowding out native species and carry diseases and pests which kill native vegetation. The native century plant, agave missionium, is currently being devastated on St. John by a non-native beetle, probably imported in an exotic Agave.
· If imported tropicals are used in landscaping, it is suggested that their use be concentrated around buildings for ease of watering and where the most environmental disruption has taken place during construction. As landscaping progresses outward from the habitable spaces it can transition from exotic to native. In this way, the perimeter greenbelt around the property can remain undisturbed natural/native vegetation.
· Owners are encouraged to minimize the use of chemical fertilizers, herbicides and pesticides that will leach into the substrata and eventually into the ocean. Natural and organic remedies are recommended.