Stormwater Management – Above Green

(3-5 points)

Intent

To reduce runoff volume, prevent erosion, flooding and recharge groundwater.

Requirements

Option 1: Rainfall event based (3-5 points)

Provide adequate infrastructure to manage stormwater within the city to demonstrate reduction in runoff, maximum capture, treatment and reuse of stormwater for a minimum of 60th percentile of local or regional rainfall event for ten year 24-hr rainfall event data. Refer the methodology given in Part I, Section E of U.S. EPA Section 438 Technical Guidance on Implementing the Stormwater Runoff Requirements for Federal Projects of the Energy Independence and Security Act to obtain 60th percentile rainfall event. Points are awarded according to Table 4. Table 4 Points for retaining percentile of rainfall retained in the city or community

Percentile rainfall retained	Points
60th percentile	3
80th percentile	4
90th percentile	5

References: LEED v4 ND GIB Credit: Rainwater Management SITES v2 Water Prerequisite 3.1: Manage Precipitation on Site SITES v2 Water Credit 3.3: Manage Precipitation beyond Baseline

Option 2. Reducing post-development stormwater run-off¹ (3-5 points)

Reduce post-development stormwater run-off by preserving pre-development runoff conditions in the planned city or community. The post-construction rate, volume, duration and temperature of runoff should not exceed the pre-development rates and the predevelopment hydrology should be replicated through design and other appropriate strategies. These goals should be accomplished through the use of infiltration, evapotranspiration, and/or rainwater harvesting and reuse.

Table 5: Points for preserving pre-development to post-development run-off conditions in the city or community

Pre-development to post-development runoff percentage	Points
15%	3
10%	4
Lesser than 10%	5

Option 3: Green Stormwater Infrastructure (3-5 points)

Ensure that 35% of the jurisdiction’s land area has designated green stormwater infrastructure providing bioretention and infiltration services that are interconnected. Provide details on strategies planned to be adopted to inspect and maintain the stormwater management facilities.

Table 6 Points for percentage of land area with designated stormwater infrastructure

% of land area with designated stormwater infrastructure	Points
35%	3
40%	4
50%	5

Reference: STAR NS-1 Green Infrastructure, Outcome 1: Green Stormwater Infrastructure

In a manner best replicating natural site hydrology processes, retain (i.e. infiltrate, evapotranspirate, or collect and reuse) on site the runoff² from the developed site for Option 1, Option 2 and Option 3. For all cities and communities, the use of coal tar sealants shall be prohibited in any application exposed to stormwater, wash waters, condensates, irrigation water, snowmelt, or icemelt. A combination of Low Impact Development (LID) approaches are recommended (but not required) as they are holistic measures which maximize benefits. In contrast to LID, conventional stormwater techniques include grey infrastructure, such as detention or retention ponds, pipes, and vaults. Conventional grey infrastructure devices may be accepted only if integrated within a holistic LID system (i.e. a combination of LID techniques).