Stormwater Management – Above Green

(2 points)

Intent

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

Requirements

Option 1. Flooding Incidences (2 points)

Path 1. No reported flooding¹ incidences in past five years

Provide the following details:

Precipitation volume for which the stormwater infrastructure has been designed.
Strategies adopted to manage stormwater beyond its designed limits.
Trend-line showing reduction in stormwater flooding events over past five years.
Strategies adopted to inspect and ensure maintenance of existing stormwater facilities.

Path 2. Reported flooding incidences in past five years

Report on areas within the city that have faced flooding. In a manner best replicating natural site hydrology processes, retain (i.e. infiltrate, evapotranspirate, or collect and reuse) on site the runoff for, at minimum, the 60th percentile of regional or local rainfall for ten-year 24-hr rainfall event data using low-impact development (LID) and green-infrastructure (GI) practices. 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. Cities or communities that have taken initiatives to manage stormwater, provide data trend-line showing reduction in stormwater flooding events over past five years. Additionally, provide details on strategies adopted to inspect and ensure maintenance of existing stormwater management facilities. Adopt techniques to infiltrate, evapotranspirate, collect and reuse water for areas, such as pavements, walkways, parks, open spaces and others.

References: LEED v4 ND GIB Credit: Rainwater Management SITES v2 Water Prerequisite 3.1: Manage Precipitation on Site LEED v4.1 BD+C SS Credit: Rainwater Management

Option 2. Green Stormwater Infrastructure (2 points)

Demonstrate that 35% of the jurisdiction’s land area has designated green stormwater providing bioretention and infiltration services that are interconnected. Provide details on strategies adopted to inspect and ensure maintenance of existing stormwater management facilities and techniques to infiltrate, evapotranspirate, collect and reuse water for areas, such as pavements, walkways, parks, open spaces, and others.

Reference: STAR NS-1 Green Infrastructure, Outcome 1

For cities or communities following Case 2 of Option 1 or Option 2, adopt techniques² to infiltrate, evapotranspirate, collect and reuse water for areas such as pavements, walkways, parks, open spaces and others within the city.

¹ Flood is the overflowing of the normal confines of a stream or other body of water, or the accumulation of water over areas that are not normally submerged. Floods include river (fluvial) floods, flash floods, urban floods, pluvial floods, sewer floods, coastal floods, and glacial lake outburst floods. https://www.ipcc.ch/pdf/special-reports/srex/SREX-Annex_Glossary.pdf , Accessed on December 17, 2018.

²Examples of acceptable techniques to achieve above requirements: • Planting rain gardens with native or adapted plant material (e.g. trees shrubs); • Installing a vegetated roof; • Using permeable paving, consisting of porous above-ground materials (e.g., open pavers, engineered products), a base layer designed to drain water away from the building, and (often) a 6-inch-deep (150 millimeters) subbase; and • Installing permanent infiltration or collection features (e.g., vegetated swale, rain garden, rainwater cistern) that can retain 100% of the runoff from at minimum, the 80th percentile of regional or local rainfall events. Cities may also refer to Urban Best Management Practice Database and Codes by Maryland Department of Environment that provides a list of BMPs under the category of environmental site design, structural and other practices. https://mde.maryland.gov/programs/water/stormwatermanagementprogram/documents/Urban%20BMP%20Database%20for%20Phase%20II%20MS4s%202016.pdf. Accessed on March 01, 2019.