Intent: Conserve existing natural areas and restore damaged areas to provide habitat and promote biodiversity.
On greenfield sites, limit all site disturbance to 40 feet beyond the building perimeter; 10 feet beyond surface walkways, patios, surface parking and utilities less than 12 inches in diameter; 15 feet beyond primary roadway curbs and main utility branch trenches; and 25 feet beyond constructed areas with permeable surfaces (such as pervious paving areas, stormwater detention facilities and playing fields) that require additional staging areas in order to limit compaction in the constructed area.
On previously developed or graded sites, restore or protect a minimum of 50% of the site area (excluding the building footprint) with native or adapted vegetation. Native/adapted plants are plants indigenous to a locality or cultivars of native plants that are adapted to the local climate and are not considered invasive species or noxious weeds. Projects earning SS Credit 2 and using vegetated roof surfaces may apply the vegetated roof surface to this calculation if the plants meet the definition of native/adapted.
Greenfield sites are those that are not previously developed or graded and remain in a natural state. Previously developed sites are those that previously contained buildings, roadways, parking lots, or were graded or altered by direct human activities.
Response: Segmented retaining wall units or stacked landscaping blocks can reduce site disturbance in landscaping projects by allowing the natural contours of the site to be respected and provide an overall natural look. Retaining wall units or landscape blocks can also be used when replacing existing (rotting) timbers without having to disturb much surrounding soil.
Intent: Limit disruption of natural water hydrology by reducing impervious cover, increasing on-site infiltration, reducing or eliminating pollution from stormwater runoff, and eliminating contaminants.
CASE 1 — EXISTING IMPERVIOUSNESS IS LESS THAN OR EQUAL TO 50%
Implement a stormwater management plan that prevents the post-development peak discharge rate and quantity from exceeding the pre-development peak discharge rate and quantity for the one- and two-year 24-hour design storms.
Implement a stormwater management plan that protects receiving stream channels from excessive erosion by implementing a stream channel protection strategy and quantity control strategies.
CASE 2 — EXISTING IMPERVIOUSNESS IS GREATER THAN 50%
Implement a stormwater management plan that results in a 25% decrease in the volume of stormwater runoff from the two-year 24-hour design storm.
Response: Landscaping pavers can help contain stormwater. Permeable pavers can function as hard surfaces while allowing water to percolate into the soil recharging local aquifers.1
Intent: Limit disruption and pollution of natural water flows by managing stormwater runoff.
Requirements: Implement a stormwater management plan that reduces impervious cover, promotes infiltration,
and captures and treats the stormwater runoff from 90% of the average annual rainfall1 using
acceptable best management practices (BMPs).
BMPs used to treat runoff must be capable of removing 80% of the average annual post
development total suspended solids (TSS) load based on existing monitoring reports. BMPs are considered to meet these criteria if (1) they are designed in accordance with standards and specifications from a state or local program that has adopted these performance standards, or (2) there exists in-field performance monitoring data demonstrating compliance with the criteria. Data must conform to accepted protocol (e.g., Technology Acceptance Reciprocity Partnership [TARP], Washington State Department of Ecology) for BMP monitoring.
Response: Recommended best management practices for achieving this credit include the use of porous pavements.2 Landscaping pavers can help contain stormwater. Permeable pavers can function as hard surfaces while allowing water to percolate into the soil recharging local aquifers.1
Intent: Reduce heat islands (thermal gradient differences between developed and undeveloped areas) to minimize impact on microclimate and human and wildlife habitat.
Provide any combination of the following strategies for 50% of the site hardscape (including roads, sidewalks, courtyards and parking lots): Shade (within 5 years of occupancy), Paving materials with a Solar Reflectance Index (SRI)2 of at least 29, Open grid pavement system.
Place a minimum of 50% of parking spaces under cover (defined as under ground, under deck, under roof, or under a building). Any roof used to shade or cover parking must have an SRI of at least 29.
Response: Light colored, high albedo of high reflectance (0.30 or greater) paving blocks such as Turfstone or an open lattice type paver can reduce the amount of on-site heat generated when the sun hits the pavement.