Sidewalk Stormwater Management Practices

The most common type of Planted Stormwater Management Practice is typically an area located along the curb of a sidewalk, graded to capture stormwater, and planted with an understory of shrubs and herbaceous material, and sometimes trees. Inlet structures such as curb cuts and grates allow for stormwater from the adjacent roadway to enter the planted area and overflow to exit. Consisting of right-of-way Rain Gardens and Infiltration Basins, the City will install and maintain these practices. Other entities may also install these practices and should consult with DEP and DOT accordingly. Any practice not maintained by the City will require an agreement. Review DEP’s interactive map.

Dean Street, Brooklyn
Lafayette Avenue, Bronx

Benefits

Review Benefits of Plantings in the ROW

  • Reduced stormwater entering sewers during storms
  • Can help to improve water quality in local waterways
  • Healthier plants and greater survival rates when appropriate plants are used
  • Can improve street drainage and may reduce ponding on streets and sidewalks

Considerations

Review Key Considerations

Reference Standards

Environmental and Existing Conditions

  • Designers should perform environmental due diligence to ensure installations will not exacerbate preexisting subsurface contamination, including, but not limited to, researching current and past uses of the site, and reviewing publicly available local, state, and federal databases. Additional environmental analysis, and potentially site remediation, may be necessary
  • Retrofitting existing plantings may be feasible if there is limited grade change and in situ soils are appropriate; special care must be given to tree roots
  • Where retrofitting, existing species must be able to tolerate higher levels of water
  • Avoid in areas adjacent to retaining structures, structural foundations, critical infrastructure, or on roadways elevated atop a retaining wall structure; cannot be sited within 25 feet of above or below-ground MTA structures

Performance

  • Plants should tolerate salts, sediment, contamination, and highly variable levels of water availability
  • Leaves, litter, and other material may clog inlets or outlets and could impact overall performance and aesthetics of the installation. Locations with heavy sediment or trash and debris loading will require frequent cleaning and should be avoided

Maintenance

  • Stormwater management practices funded and approved by DEP will be maintained by DEP; all other installations are encouraged, but will require a maintenance agreement

Application

  • Install in all areas with Tree Beds, Roadway Plantings, Sidewalk Plantings, Plaza Plantings, and Limited-Access Arterial Plantings
  • Right-of-way Rain Gardens are the most frequently used and generally mimic the siting criteria used for Tree Beds
  • Right-of-way Infiltration Basins are used in areas with narrower sidewalks or higher pedestrian volumes where plants are not feasible or an existing grass strip should be maintained; they are not recommended for areas where vehicles frequently mount the sidewalk
  • Installations can be pursued in partnership with DEP, Parks, or another maintenance partner

Design

DEP Standards for right-of-way Bioswales, Rain Gardens, Infiltration Basins, Stormwater Greenstreets, and other practices such as Precast Porous Concrete Panels are available on the DEP website.

Review Key Considerations.

Review design guidance for Sidewalk Plantings.

Siting

  • Green Infrastructure Siting Criteria is available on the DEP website.
  • Locate treatments at least 7 feet from any below-ground vaults or basements to prevent water damage to these structures.
  • A minimum 8-foot clear path must generally be maintained. DOT may require a lesser or greater clear path on specific corridors based on the Pedestrian Mobility Plan. Exceptions may be approved by DOT and DEP on a case-by-case basis.

Sizing and Water Flow

  • Stormwater management areas should be sized in relation to the tributary drainage area to handle the volume of water entering them; consult DEP’s latest Green Infrastructure Standards.
  • Direct runoff into planted areas via porous pavement, curb inlets, stormwater inlets with sub-surface pipes, or other methods approved by DEP. Review Permeable Interlocking Concrete Paver and Precast Porous Concrete Panels.
  • Utilize a pre-treatment system such as grates, a vegetative filter, or weirs to filter and collect sediment and floatables into a concentrated area; this system should be easy to clean out and will reduce the frequency of maintenance visits.
  • Water entering the planted area should be detained and allowed to infiltrate into the soil; grade soil as a swale or depress the soil level below the inlet and outlet structures.
  • Select soils that allow more rapid infiltration than typical horticultural soils and resist compaction while still supporting plant material.
  • Overflow must be allowed to flow to an existing catch basin; consider the use of graded outlet structures or overflow drains to direct excess water from larger storms into the sewer system.

Planting

  • Review the Plant Finder for DEP-approved green infrastructure plantings and other plants that perform well in the right-of-way. All selections must be made based on specific site considerations.
  • Use canopy trees, low shrubs, and groundcover to maintain visibility.
  • Surface treatment may be plantings, lawn, or concrete depending on context and community feedback.
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