All open parking areas with 18 spaces or more or 6,000 square feet or more in area that front upon a street shall be screened at the street line by a perimeter landscaped area at least seven feet in width measured perpendicular to the street line. Such perimeter landscaped area may be interrupted only by vehicular entrances and exits. Walkways may also traverse the perimeter landscaped area in order to provide a direct connection between the public sidewalk and a walkway within or adjacent to the open parking area. In the event a perimeter landscaped area is greater than seven feet in width, the first seven feet adjacent to the open parking area must comply with paragraphs (a) and (b) of this Section. The remainder of the landscaped perimeter area may comply with paragraphs (a) and (b) or be comprised of any combination of grass, groundcover, shrubs, trees or other living plant material.
The perimeter landscaped area shall comply with the following requirements:
(a) Grading, drainage and soil
The open parking area shall be graded to allow stormwater runoff to drain into all required perimeter landscaped areas and planting islands required pursuant to Section 37-922 (Interior landscaping). The perimeter landscaped area shall be comprised of soil with a depth of at least two feet, six inches, measured from the adjoining open parking area. Beneath such soil, filter fabric and one foot of gravel shall be provided. Proper drainage rates shall be attained through underdrains that are connected to detention storage that meets the drainage and flow requirements of the Department of Environmental Protection or through infiltration through the surrounding soil volume. If underdrains are not provided, soil boring tests shall be conducted by a licensed engineer to ensure that ponded surface water is drained in at least 24 hours. The perimeter landscaped area shall have an inverted slope to allow a minimum of six inches and a maximum of one foot of stormwater ponding, and surface ponding must drain in at least 24 hours. To allow for adequate drainage, elevated catchbasins shall be placed in the planting island above the ponding level. A raised curb shall edge the perimeter landscaped area, shall be at least six inches in height and shall contain inlets at appropriate intervals to allow stormwater infiltration from the open parking area.
However, where the Commissioner of Buildings determines that due to the natural sloping topography of the site the drainage provisions of this paragraph, (a), would be infeasible for a perimeter landscaped area, such drainage provisions may be waived. In lieu thereof, such perimeter landscaped area shall be comprised of soil with a depth of at least three feet measured from the adjoining open parking area. A raised curb shall edge the perimeter landscaped area and be at least six inches in height. The planting requirements of paragraph (b) of this Section shall apply to such perimeter landscaped areas, except that plantings need not be selected from the lists in Section 37-963.
(1) Parking lot frontage
The first two feet of the planting island fronting the open parking area shall be comprised of mulch and densely planted with groundcover above jute mesh to stabilize the inverted slope. This area may be used as an automobile bumper overhang area and may be included in calculating the required depth of an abutting parking space. All required groundcover shall be selected from the list in Section 37-963.
(2) Sidewalk frontage
The remainder of the perimeter landscaped area shall be densely planted with shrubs at a distance of 24 inches on center and maintained at a maximum height of three feet above the surface of the adjoining public sidewalk. All required shrubs shall be selected from the list in Section 37-963.
One two-inch caliper tree shall be provided for every 25 feet of open parking area street frontage. Fractions equal to or greater than one-half resulting from this calculation shall be considered to be one tree. Such perimeter trees shall be staggered wherever possible with street trees, but in no event shall perimeter trees be planted closer than 15 feet on center or within three feet to a perimeter screening area curb. Furthermore, a radius distance of at least 20 feet shall be maintained between trunks of perimeter trees and street trees. If such distances cannot be maintained, the perimeter tree shall be waived in that location. However, if a street tree cannot be planted in the public sidewalk adjacent to the perimeter screening area because the Department of Parks and Recreation has determined that it is infeasible to plant a tree in such location, such tree shall be planted instead within the perimeter screening area adjacent to such portion of the public sidewalk and credited towards the amount of perimeter trees required pursuant to this paragraph. However, any perimeter tree within 15 feet of an elevated rail line or elevated highway shall be waived. All required perimeter trees shall be selected from the list in Section 37-961.
Utilities and signs permitted in Sections 32-62, 32-63 or 42-52 may be located in the perimeter screening area. Ornamental fencing, excluding chain link fencing, with a surface area at least 50 percent open is permitted in the perimeter screening area, provided such fencing does not exceed four feet in height and is located at least five feet from the street line.