The provisions of this Section shall apply to the street wall of the ground floor and second floor level enlargement. For the purposes of this Section, a building wall that faces a publicly accessible open area or through block arcade shall also be considered a street wall, and the provisions of this Section for new building walls fronting on a publicly accessible open area shall also apply to new building walls fronting on a through block arcade, except as otherwise specified. The City Planning Commission may authorize a modification of the provisions of this Section pursuant to Section 91-842 (Authorization to modify design requirements).

(a)        Location of enlargement

(1)        Location of new building walls

All new building walls shall extend to the full height of the arcade. New building walls may only be located between the column face closest to an existing street wall and the column face furthest from an existing street wall or the street wall location of the floor above, except that new building walls within an existing through block arcade that do not face a street may extend past the column face furthest from the existing street wall provided that the standards for through block arcades set forth in Section 12-10 (DEFINITIONS) and all other provisions of this Section are met. New building walls within an existing through block arcade that do not face a street shall not be required to extend for the full height of the through block arcade.

(2)        Length of new building walls

An enlargement shall extend for the full length of the street wall, except for the locations specified on Map 9 in Appendix A of this Chapter and except if a corner arcade that adjoins the Water Street street line and another street line or publicly accessible open area is provided in accordance with the provisions of paragraph (c) of Section 37-53 (Design Standards for Pedestrian Circulation Spaces) which may provide a clear path 10 feet wide. However, an enlargement shall not be required along the length of the street wall occupied by an existing parking or loading entrance. Where an enlargement within an arcade extends along two or more street walls, the enlargement shall also include the area where the arcade areas intersect, except as otherwise provided in this Section, and the location of new building walls in such area shall be subject to the provisions of paragraph (a)(1) of this Section.

(b)        Permitted uses within an enlargement

(1)        Requirements for all frontages

(i)        Retail uses

The street frontage or frontage along a publicly accessible open area of the enlarged portion of the ground floor level shall be allocated exclusively to indoor public spaces that are provided in accordance with the provisions of Section 91-834 or the uses permitted by Sections 91-111 (Additional uses in C5 Districts) and 91-12 (Uses on Designated Retail Streets), except that Use Groups 5A, 7A, 7B, 8B, 9A, 10A, 12A, 12B, or 12C shall not be permitted. However, bicycle rental or repair shops and studios for art, music, dancing or theater shall be permitted. Residential uses shall be limited to lobbies permitted by paragraph (c)(2) of this Section.

All uses permitted by this paragraph shall occupy a height no less than that of the ground floor level, and shall occupy a depth no less than that of the enlargement.

(ii)        Parking, loading and mechanical equipment

No garage entrances, driveways, parking spaces or loading berths shall be permitted within an enlargement. No exhaust vents or mechanical equipment shall be permitted on any new building wall unless such exhaust vents are more than 15 feet above the level of the curb.

(iii)        Maximum street wall width

On the ground floor portion of an enlargement for the following Use Group 6 uses: the maximum street wall width of a bank or loan office shall not exceed 30 feet; and the maximum street wall width of a drug store shall not exceed 50 feet.

(2)        Additional use requirement for a publicly accessible open area or through block arcade

At least 50 percent of the total frontage of all new building walls fronting on a publicly accessible open area or through block arcade, excluding such frontage occupied by building lobbies, shall be occupied by retail or service establishments permitted by paragraph (b)(1) of this Section. As an alternative, the amount of frontage required by this paragraph for occupancy by retail or service establishments may be partially or fully located along existing building walls fronting on the publicly accessible open area or through block arcade and the transparency requirements of paragraph (c)(3) of this Section shall apply to such frontage.

Libraries, museums and art galleries are permitted uses that may front on a publicly accessible open area. Banks shall not be a permitted use on any publicly accessible open area or through block arcade. Uses required by this paragraph shall be directly accessible from the publicly accessible open area or through block arcade.

(c)        Frontage

(1)        Number of establishments

Along the longest street wall of the ground floor level enlargement, at least two establishments permitted by paragraph (b) of this Section shall be provided on the ground floor level. Frontage that is solely dedicated to access a use on a level other than the ground floor level shall not constitute an establishment for the purposes of this paragraph.

(2)        Access, entrances and lobbies

The street wall frontage of an enlarged portion of the ground floor level may be occupied by the primary entrance for the principal use of the building, provided that such primary entrance shall not exceed a street wall width of 50 feet along Water Street, or, along other streets, a street wall width of 40 feet, or 25 percent of the aggregate width of street wall along such street frontage, whichever is less.

For a primary entrance that fronts on a publicly accessible open area, such entrance shall occupy a minimum frontage length of 20 feet or a length equal to the distance between the two closest columns adjacent to the publicly accessible open area, whichever is less. A primary entrance for the principal use of the building may be located along a through block arcade or indoor public space provided in accordance with Section 91-834 (Indoor public spaces), but may only occupy a maximum frontage length of 25 feet.

Where more than 50 percent of the length of the enlargement is occupied by a primary entrance permitted by this paragraph, retail or service establishments with an aggregate frontage length equal to at least 50 percent of the length of the enlargement shall be required along new or existing building walls along the same street frontage as the enlargement, and the transparency requirements of paragraph (c)(3) of this Section shall apply to such frontage along existing building walls.

(3)        Transparency and flood resilience

The ground floor level street wall between existing columns shall be glazed with transparent materials, which may include show windows, transom windows or glazed portions of doors, except for certain uses set forth in Section 37-31 (Applicability). Such transparent materials shall occupy at least 70 percent of the surface area of such ground floor level street wall between a height above grade of two feet and 14 feet or the height of the ground floor ceiling, whichever is lower.

Where the use located within the ground floor level enlargement fronts on an arcade that remains open and accessible, the length of such frontage shall be glazed with transparent materials in accordance with the provisions of this paragraph.

Permanent fixtures for temporary flood control devices and associated emergency egress systems that are assembled prior to a storm and removed thereafter and are affixed to a column may obstruct any transparent portion of a new building wall. Such permanent fixtures may be considered a transparent portion of a new building wall. Additionally, such permanent fixtures shall be encased in a decorative material. Temporary flood control devices and associated emergency egress systems shall be permitted in front of any new building wall for a reasonable period of time prior to and after a storm event, as determined by the Department of Buildings.