Design site features to minimize erosion and runoff from the home site.
Note: Certain surface water management strategies may be regulated, restricted, or even prohibited by local water authorities or code requirements.
4.1 Permeable lot (maximum 4 points, as specified in Table 1). Design the lot such that at least 70% of the buildable land, not including area under roof, is permeable or designed to capture water runoff for infiltration on-site. Area that can be counted toward the minimum includes the following:
- Vegetative landscape (e.g., grass, trees, shrubs).
- Permeable paving, installed by an experienced professional. Permeable paving must include porous above ground materials (e.g., open pavers, engineered products) and a 6-inch porous subbase, and the base layer must be designed to ensure proper drainage away from the home.
- Impermeable surfaces that are designed to direct all runoff toward an appropriate permanent infiltration feature (e.g., vegetated swale, on-site rain garden, or rainwater cistern).
4.2 Permanent erosion controls (1 point). Design and install one of the following permanent erosion control measures:
a) If portions of the lot are located on a steep slope, reduce long-term runoff effects through use of terracing and retaining walls.
b) Plant one tree, four 5-gallon shrubs, or 50 square feet of native groundcover per 500 square feet of disturbed lot area (including area under roof ).
4.3 Management of runoff from roof (maximum 2 points). Design and install one or more of the following runoff control measures:
a) Install permanent stormwater controls (e.g., vegetated swales, on-site rain garden, dry well, or rainwater cistern) designed to manage runoff from the home (1 point).
b) Install vegetated roof to cover 50% of the roof area (0.5 point).
c) Install vegetated roof to cover 100% of the roof area (1 point).
d) Have the site designed by a licensed or certified landscape design or engineering professional such that all water runoff from the home is managed through an on-site design element (2 points).
Table 1. Permeable Area
|Percentage of buildable lot (excluding area under roof) that is permeable||Points|