(3)   Use Regulations.
The following standards shall apply to all Residential Housing Projects in addition to those of the base zoning district, as indicated in § 14-602(4):
(a)   At least twenty percent (20%) of all dwelling units (rounded up, if fractional) shall be provided and maintained as affordable, as regulated in § 14-528(6) (Affordability), and must meet the following conditions:
(.1)   At least ten percent (10%) of all dwelling units (rounded up, if fractional) shall be provided and maintained as affordable and located on the same site as the majority of other dwelling units included in the Residential Housing Project;
(.2)   All dwelling units provided to meet the requirements of this subsection (a) must be located within 1.5 miles of the majority of dwelling units included in the Residential Housing Project;
(.3)   Dwelling units provided pursuant to this subsection (a) may not be used to satisfy the requirements of subsection (b), below.
(b)   For each 5,000 sq. ft. of floor area of group living provided, at least one dwelling unit shall be provided and maintained as affordable, as regulated in § 14-528(6) (Affordability), within 1.5 miles of the site where the group living use is provided. Dwelling units provided pursuant to this subsection (b) may not be used to satisfy the requirements of subsection (a), above.
(c)   Provided, however, subsections (3)(a) and (3)(b) shall not apply if the owner or owners of the Residential Housing Project enters into a binding agreement with the Department of Planning and Development pursuant to which the owner or owners will agree to pay the City a payment in lieu of providing affordable housing in accordance with the following requirements:
(.1)   The payment shall be calculated as one percent (1%) of Hard Construction Costs (as defined in Section 17-108) for construction of the Residential Housing Project, and paid in two installments;
(.2)   The first installment payment shall be equal to a good faith estimate by the owner or owners of the Residential Housing Project of eighty percent (80%) of one percent (1%) of Hard Construction Costs for the construction of the Residential Housing Project. This first payment shall be paid prior to the issuance of a building permit. At the time of the payment, the owner or owners of the Residential Housing Project shall sign a declaration of the good faith estimate of the Hard Construction Costs for the construction of the Residential Housing Project and provide a construction budget to support the calculation of the good faith estimate of Hard Construction Costs;
(.3)   The second installment shall be paid prior to the issuance of a certificate of occupancy for the Residential Housing Project, and shall be equal to the difference between the first payment and one percent (1%) of the actual Hard Construction Costs incurred for the construction of the Residential Housing Project. At the time of the payment, the owner or owners of the Residential Housing Project shall sign a declaration of the actual Hard Construction Costs incurred for the construction of the Residential Housing Project, provide a construction budget to support the calculation of the actual Hard Construction Costs incurred and deliver a third-party certification, from a professional with expertise in managing construction budgets for similar projects, of the amount of the actual Hard Construction Costs incurred; and
(.4)   The Department of Planning and Development shall agree to use such money for the purposes set forth in Section 21-1605 (Trust Fund Assets Held in the Non-Recording Fee Sub-Fund) or Section 21-1603 (Creation, Distribution and Use of the Trust Fund's Assets).
(d)   Further provided, subsections (3)(a) and (3)(b) shall not apply to any development that has received or will receive government financial assistance conditioned upon the provision of fifty-one percent (51%) or more total units in a Residential Housing Project meeting affordability standards of a government program.