Overview
The Sustainable Sites credit category has 6 common credits between the BD+C Rating Systems. There are 5 other credits for different LEED adaptations. There is one common prerequisite, and one prerequisite specific to Schools and Healthcare.
SS Prerequisite 1 | Construction Activity Pollution Prevention
SS School Prerequisite 2 | Environmental Site Assessment
Only required for School and Healthcare projects
SS Credit 1 | Site Assessment
can earn one point for all BD&C rating systems
SS Credit 2 | Site Development Protect or Restore Habitat
can earn 1 to 2 points for all BD&C rating systems, except for Healthcare which can earn one point
SS Credit 3 | Open Space
can earn one point for all BD&C rating systems
SS Credit 4 | Rainwater Management
can earn 1 to 3 points for all BD&C rating systems, except for Healthcare which can earn 1 to 2 points
SS Credit 5 | Heat Island Reduction
can earn 2 points for all BD&C rating systems, except for Healthcare which can earn 1 point
SS Credit 6 | Light Pollution Reduction
can earn 1 point for all BD&C rating systems
It’s worth remembering which credits have multiple points associated with them. The implication there is that they have a greater environmental benefit. The Architects of LEED v4 have weighted credits based on their contributions to the seven goals mentioned in chapter one of this study guide.
We can see in this section that Rainwater Management is inherently more important than, Light Pollution Reduction. In addition, School and Healthcare projects have extra
sensitivities, which require Environmental Site Assessments, whereas that approach is optional for other rating systems.
These next credits are specific to certain rating systems.
SS School Credit | Site Master Plan
can earn one point for Schools
SS School Credit | Joint Use of Facilities
can earn one point for Schools
SS Core & Shell Credit | Tenant Design and Construction Guidelines
can earn one point for Core & Shell
SS Healthcare Credit | Places of Respite
can earn one point for Healthcare
SS Healthcare Credit | Direct Exterior Access
can earn one point for Healthcare
Bear in mind that, in the end, all rating systems have a total of 110 points, but they distribute them based on what’s important. You’ll hear it over and over again – it’s important to start early with these credits as they affect the size and shape of the footprint of your building.
SS Prerequisite 1 | Construction Activity Pollution Prevention
This prerequisite applies to all of the BD&C rating systems. The intent is to reduce pollution from construction activities by controlling soil erosion, waterway
sedimentation, and airborne dust.
The thing you need to remember is that construction activity pollution refers to erosion and sedimentation. More explicitly, erosion of top soil harms ecosystem services, and sedimentation, or silt in stormwater runoff, impairs waterways. To avoid these negative impacts of construction, teams are required to produce and follow an erosion and sedimentation control plan (ESC).
What is your project site receives little rainfall? If so, then it probably produces a lot of dust, so your pollution source is airborne and your pollution prevention plan must address dust rather than stormwater sedimentation.
Reference Standard
The ESC plan must comply with the 2012 EPA construction general permit or local standards and codes, whichever is more stringent. The EPA’s guidance is a really
common approach in LEED because it’s a national system adopted by many
municipalities. Of course, LEED says if the local codes or standards are more stringent, you have to follow those. If the local jurisdiction requires a construction general permit (CGP) based on National Pollutant Discharge Elimination System (NPDES), then using the CGP is a streamlined path and no additional ESC plan is required. Let’s look at these standards more closely.
Storm water discharges from construction activities (such as clearing, grading,
excavating, and stockpiling) that disturb one or more acres, or smaller sites that are part of a larger common plan of development or sale, are regulated under the NPDES storm water program. Prior to discharging storm water, construction operators must obtain coverage under an NPDES permit, which is administered by either the state (if it has been authorized to operate the NPDES storm water program) or EPA, depending on where the construction site is located.
Where EPA is the permitting authority, construction storm water discharges are almost all permitted under the CGP. The CGP requires compliance with effluent limits and other permit requirements, such as the development of a Storm Water Pollution Prevention Plan (SWPPP). If you have driven by a construction site before you may have seen a SWPPP permit posted on the perimeter right near the entrance to the project. The government takes these very seriously and if a project is found to be in violation of the plan the local agency may shut down construction until the issues are remedied.
For international projects you’ll need to find a local equivalent code.
Prevention Activities
Three different categories of action identified within the CGP must be followed for every project: erosion and sedimentation control, stabilization, and pollution prevention.
Erosion and sedimentation control
Providing natural buffers
Installing perimeter controls
Minimizing sediment track-out
Controlling discharges from stockpiled sediment or soil
Minimizing dust
Minimizing the disturbance of steep slopes
Preserving topsoil
Minimizing soil compaction
Protecting storm drain inlets
Maintaining control measures
Stabilization
Deadlines for initiating and completing stabilization
Criteria for stabilization
Pollution Prevention
Prohibited discharges
General maintenance requirements
Pollution prevention standards
Emergency spill notification
Fertilizer discharge restrictions
Project teams should start by evaluating the site specific needs. Pay attention to slope, rainwater management control (like existing storm sewers), weather conditions, and entrances to local roads. Every project will require different strategies to achieve the above stated actions. For example you could stabilize the soil through temporary seeding, permanent seeding, or mulching. Larger structural controls like an earth dike, terracing, riprap, and a silt fence are frequently used.
You may have driven by a construction site and seen hay bales around sewer drains or next to sidewalks, this prevents sedimentation in runoff water. In addition, gravel at the construction entrance helps keep soils on the site and off the roads. Sometimes vehicles are even washed prior to entering the public right away from a muddy jobsite.
These concepts are not just for LEED compliance. The property owner can be fined for overburdening the public infrastructure and impacting stable environmental conditions.
Weekly inspections from the local municipality enforce the ESC plan. The ESC plan is created by a civil engineer and included in the drawing set used by contractor.
SS Prerequisite 2 | Environmental Site Assessment
This one is for schools and healthcare only, which are what you would call sensitive types of occupancy. The intent is to protect the health of vulnerable populations by ensuring that the site is assessed for environmental contamination and that any environmental contamination has been remediated. The assessment shall cover soil, groundwater, and surface water.
Process
The project team will start with a phase one environmental site assessment (ESA). This assessment is superficial and limited and identifies whether contamination is suspected.
If the conclusion is, “there was a drycleaner here at some point,” that would mean one
can suspect some contamination. The report may state no contamination if the prior use was a greenfield or daycare.
If contamination is suspected, then a phase two environmental assessment is required, including specific and in-depth analysis of soil and water conditions. If contamination is found or perceived to be on the site, then you are mandated to remediate the site.
Referenced Standard
The Phase I ESA must comply with ASTM E1527-05 procedures. Typical actions include review of historical records, site visit, interviews, and a full report documenting findings. No collection of physical samples or chemical analysis is done. LEED considers a Phase I ESA valid for 180 days. If the assessment is between 180 days and one year old certain updates must be made to different sections of the assessment. An assessment older than one year must be redone.
A Phase II ESA must comply with ASTM E1903-11 procedures. It is an investigation that collects original samples of soil, groundwater, or building materials to analyze in a laboratory for quantitative values of various contaminants. Typical findings include:
petroleum hydrocarbons, heavy metals, pesticides, solvents, asbestos, and mold. Sites previously occupied for industrial or manufacturing use commonly have residual contamination.
Remediation
If a site is contaminated according to a Phase II ESA, then it must be remediated prior to re-use. Strategies vary depending on scope and type of contamination. Common
remediation activities include:
Pump and treat
Solar detoxification
Using bioreactors
Land farming
In-situ remediation
On-going monitoring
SS Credit 1 | Site Assessment
This site assessment is about everything else besides contaminants. The intent is to observe site conditions before design, and evaluate sustainable options to inform major decision. You can think of it as the integrative process for the site design. Project teams will need to document a site survey or assessment of the site’s characteristics.
Project teams need to ask – what is happening on the site in terms of soil, habitat, what are the options for space preservation, what are the human uses of the facility? This credit encourages project teams to maximize natural qualities of the site to take advantage of passive water and energy opportunities.
Elements of a Site Assessment:
Topography. Contour mapping, unique topographic features, slope stability risks.
Hydrology. Flood hazard areas, delineated wetlands, lakes, streams, shorelines, rainwater collection and reuse opportunities, TR-55 initial water storage capacity of the site (or local equivalent for projects outside the U.S.).
Climate. Solar exposure, heat island effect potential, seasonal sun angles, prevailing winds, monthly precipitation and temperature ranges.
Vegetation. Primary vegetation types, greenfield area, significant tree mapping, threatened or endangered species, unique habitat, invasive plant species.
Soils. Natural Resources Conservation Service soils delineation, U.S. Department of Agriculture prime farmland, healthy soils, previous development, disturbed soils (local equivalent standards may be used for projects outside the U.S.).
Human use. Views, adjacent transportation infrastructure, adjacent properties, construction materials with existing recycle or reuse potential.
Human health effects. Proximity of vulnerable populations, adjacent physical activity opportunities, proximity to major sources of air pollution.
Timeline
Like the integrative design credit, site assessment is done very on in the process so the findings can influence the design decisions of the project. It begins prior to the
conceptual design, which makes sense, the goal is to have the site influence the design of the project, such as where it is sited on the property, the building orientation, etc. The architect, landscape designer, civil engineer, and owner will need to work closely together early on to gather information and make informed decisions.
Research and Documentation
USGBC provides a spreadsheet project teams can use for the site inventory. The reference guide includes a list of sources for each of the categories to consider. For example the vegetation sources on the project you might bring in someone to physically identify the plant species, aerial maps from google maps for determining the boundaries on the site where vegetation is, species lists from the U.S. and Wildlife Service
Endangered species list, local land use and zoning maps to locate stream buffers and wetlands, etc.
For the other categories consider topographical maps, soil surveys, previous site assessments, and climate data.
In your final narrative, project teams should identify the design opportunities impacted by the site analysis. An example might be “The northwest corner of the property is at a lower elevation where water was more likely to run off, so we located our retention pond in that quadrant. Additionally, a soil analysis and plant inventory guided the landscape architect to create a plan to restore the natural habitats for local bird populations.”
SS Credit 2 | Site Development – Protect or Restore Habitat
The intent of this credit is to conserve existing natural areas and restore damaged areas to provide habitat and promote biodiversity. All of the BD&C rating systems can earn 1 to 2 points for this credit, except for Healthcare which can earn one point.
What’s new in LEED v4 is the setback requirements from LEED 2009 have been replaced with standards for preservation, and percentages to preserve and restore.
Approach
This credit has multiple approaches based on pre-existing site condition. All projects must preserve and protect 40% of the greenfield site condition from development and construction activity.
In addition, projects can choose either: restore on-site 30% of previously developed total area, or financial support of a land trust off-site.
Option 1: On-Site Restoration
If you’re on a previously developed site, the goal is to restore 30% of the total site area, including building footprint, with native or adaptive plants. You can’t use nonnative plants or invasive plants, and you have to restore the soil as well to bring the land closer to its original ecosystem before it was developed.
The soils have to meet the following criteria:
Soils (imported and in situ) must be reused for functions comparable to their original function. Imported topsoils or soil blends designed to serve as topsoil may not include the following:
soils defined regionally by the Natural Resources Conservation Service web soil survey (or local equivalent for projects outside the U.S.) as prime farmland, unique farmland, or farmland of statewide or local importance; or
soils from other greenfield sites, unless those soils are a byproduct of a construction process.
Restored soil must meet the criteria in categories 1 to 3 below, as well as meet either category 4 or 5:
1. organic matter 2. compaction 3. infiltration rates 4. soil biological function 5. soil chemical characteristics
In the beginning of the project you might have to bring in a local soil expert or conduct some soil analysis to see what type of soils exist around the site.
Alternative Landscapes
Projects that achieve a density of 1.5 floor-area ratio may include vegetated roof surfaces in this calculation if the plants are native or adapted, provide habitat, and promote biodiversity.
Project teams may exclude vegetated landscape areas that are constructed to
accommodate rainwater infiltration from the vegetation and soils requirements, provided all such rainwater infiltration areas are treated consistently with SS Credit Rainwater Management.
Option 2: Financial Support
If a project team chooses not to restore the site, or faces other barriers, the building owner can write a check to a land trust. This option is not providing land, or a donation of land, but money for land. It meets the intention of preserving habitat for the life of the building.
Project teams must provide financial support equivalent to at least $0.40 per square foot ($4 U.S. per square meter) for the total site area (including the building footprint).
Financial support must be provided to a nationally or locally recognized land trust or conservation organization within the same EPA Level III ecoregion or the project’s state.
For U.S. projects, the land trust must be accredited by the Land Trust Alliance. For projects outside of the U.S., the financial support must be provided to a land trust within 100 miles of the project (160 kilometers).
Strategies
Meet local zoning requirements, or if not needed, apply for a waiver. Identify areas for vegetation. Replace paved areas with landscaped areas. That’s the key for this credit - that you’re restoring a previously developed site to a native habitat condition. On a greenfield site, you would establish non-disturbance boundaries during construction.
That’s saying, “Okay, general contractor, where can you stage your equipment, your trailer, your debris bins so they’re not going to encroach on the existing habitat?” That’s part of reducing disturbance of construction activity. Heavy machinery compacts soil and weakens its ability to perform its role of filtration in the ecosystem. Consider using paved areas for staging.
Furthermore, think about the building’s placement (if you have that opportunity), and even the building plan. Look at things like stacked program, tuck-under parking or sharing facilities with neighboring buildings.
Calculation Examples
Scenario 1If you had a 20,000 sf site that was 10,000 sf previously developed and 10,000 sf greenfield, the requirements apply to both portion. First, protect 40% of the 10,000 sf greenfield area, or 4,000 sf. In addition, for the previously developed portion of the site, 30% of it must be restored, or 3,000 sf.
All together, the project will contain 7,000 sf of native and adaptive landscaping, or 35%
of total site area. That leaves 13,000 sf for the building footprint, parking, hardscapes, and roads. Remember, if a site contains both greenfield and previously developed conditions, it must meet both requirements.
Scenario 2
A project site is 10 acres (4 hectares). 5 acres (2 hectares) of the site have been previously developed, including a 1 acre (0.4 hectare) building footprint. How much money must be contributed to a land trust? (Hint: There are 43,560 square feet in an acre, and 10,000 square meters in a hectare.)
10 x 43,560 sf x 0.4$/sf = $174,240 or 4 ha x 10,000 x 4$/ha = $160,000. For large projects, it will be more cost effective to restore on-site.
Rating System Adaptations
In the schools rating system, dedicated athletic fields that are solely for athletic uses are exempted from the soil restoration criteria. These areas may not count toward the minimum required area.
Case Study
Ball Horticultural Company wanted to set an example for other corporations by restoring areas on their corporate headquarters in West Chicago to an ecologically stable
landscape.
This included improving erosion control, wildlife habitat, diversity, aesthetics, and air and water quality. In planning the project, the property was divided into a wetland mitigation area, south woods, west woods, Oak savanna, existing lawn, tall-grass prairie, and an old field.
To gain acceptance within the community the company began restoration of the tall-grass prairie. This area needed the least amount of invasive plant removal and gave the
quickest results with flowers blooming the following spring. To connect the prairie to the wetland, the west woods and old-field were restored next. With the opening of the canopy in the west woods, more sunlight reached the ground stimulating the growth of native trees, shrubs, wildflowers, and grasses. Seed and woody plants were installed within the woods to enhance the remnant populations.
The wetland mitigation area was vegetated in a year later, and it required a DuPage County Stormwater permit. A new detention basin and the existing lawn were seeded with native species, while clearing and seeding began in the South woods as well.
After installation was complete, interpretive signs were installed as well as houses for Blue Birds, Wood Ducks, and Tree Swallows.
SS Credit 3 | Open Space
The intent of this credit is to create exterior open space that encourages interaction with the environment, social interaction, passive recreation, and physical activities.
It’s crucial that you differentiate credits with similar names. The last credit was called protect or restore habitat; this one is open space. What’s the difference?
Both are vegetated landscapes. Open space is a generic description for any kind of tree, shrub, groundcover, water, and minimal pavement. Habitat is a specific type of
landscape that supports the native ecology and habitats for indigenous plants and animals.
Habitat is generally for the animals and not people. Open spaces must be usable to the project, as defined by the intent of the credit.
Habitat is generally for the animals and not people. Open spaces must be usable to the project, as defined by the intent of the credit.