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In all districts, rear yard equivalents shall be provided on through lots in accordance with this Section. 

1. Exceptions
   
   No rear yard equivalent regulations shall apply:
   1. to any through lots that extend less than 110 feet in maximum depth from street to street; 
   2. to large sites;
   3. to any zoning lot that includes a through lot portion that is contiguous on one side to two corner lot portions and such zoning lot occupies the entire block frontage of a street; or 
   4. to any zoning lot occupying an entire block. 
2. Depth requirement 
   1. For standard lots
      
      On any through lot that is 190 feet or more in maximum depth from street to street, for buildings or portions thereof at or below a height of 75 feet, a rear yard equivalent consisting of an open area with a minimum depth of 40 feet shall be provided, and above a height of 75 feet, where permitted, a rear yard equivalent of 60 feet shall be provided. 
   2. For shallow lots
      
      The depth of a rear yard equivalent may be reduced where a through lot is less than 190 feet deep at any point, and the shallow lot condition was in existence on December 15, 1961, and, subsequently, such shallow lot condition has neither increased nor decreased in depth.
      
      For such shallow through lots, or portions thereof, the depth of a required rear yard equivalent set forth for standard through lots in this Section, may be reduced by one foot by which the depth of a zoning lot, or portion thereof, is less than 190 feet. However, in no event shall the minimum depth of a required yard, or portion thereof, be reduced to less than 20 feet.
3. Location requirement
   1. Standard location
      
      A rear yard equivalent shall be provided midway, or within 10 feet of being midway, between the two street lines upon which such through lot fronts.
   2. Alternative location allowances
      
      Alternatively, for zoning lots utilizing the height and setback provisions for eligible sites in Section 23-434, the tower regulations of Section 23-435, or other height and setback provisions of this Resolution that modify or supersede the underlying provisions for R10 Districts without a letter suffix, or for shallow lots eligible for the provisions of paragraph (b)(2) of this Section, the following options may be applied: 
      1. open areas adjoining and extending along the full length of either or both street lines, where the combined depth of such open areas is equivalent to the depth of the required rear yard equivalent;  
      2. open areas adjoining and extending along the full length of either or both side lot lines, where the combined width of such open areas is equivalent to the depth of the required rear yard equivalent. If any open area extending along a side lot line is provided at any level, it shall have a minimum width of five feet, measured perpendicular to the side lot line, and extend along the entire side lot line. The allowances for permitted obstructions in any yard or rear yard equivalent set forth in Sections 23-311 and 23-312 shall be permitted in such open areas.

Any such rear yard equivalent shall be unobstructed from its lowest level to the sky, except as provided in Section 23-341 (Permitted obstructions in required yards or rear yard equivalents).