1. Applicability and purpose.
(i) A Preliminary Drainage Plan shall be prepared for the following developments:
(1) New nonresidential construction or subdivision.
(2) New multi-family subdivision or construction (3+ units),
(3) New single-family residential subdivision or construction, or
(4) Any development or construction if impervious surface is increased unless exempted by the City Engineer.
(5) Any development or construction requiring Preliminary Plat.
(ii) The Preliminary Drainage Plan shall depict the watershed(s) that the property or development will impact and how the runoff from the fully-developed watershed will be conveyed to, through, and from the development.
(1) The Preliminary Drainage Plan must comply with the standards outlined in this UDC, Engineering Technical Manual, and other City codes.
(iii) The Preliminary Drainage Plan shall demonstrate the intent of the Developer or Property Owner with regard to conveyance and proper handling of stormwater runoff. The preliminary drainage plan shall show preliminary inlet and storm drain placement and sizing, preliminary water quality/detention pond location and sizing, and any necessary open channels that are required for the conveyance of stormwater runoff.
(iv) The Preliminary Drainage Plan may satisfy the stormwater management portion of the Storm Water Pollution Prevention Plan (SWPPP) that is required for construction activities; however, the Preliminary Drainage Plan is not a substitution for the SWPPP.
(v) The review of the Preliminary Drainage Plan does not constitute final drainage plan approval or authorize a waiver to any of the Subdivision Regulations and Development Standards.
2. Plan required and previous plans.
(i) A Preliminary Drainage Plan shall be provided, at the Applicant’s expense, for the area proposed for development. The Preliminary Drainage Plan shall depict any property impacted by the development, including those not planned for earth disturbance.
(ii) For property with a previously accepted Preliminary Drainage Plan, the accepted Preliminary Drainage Plan may be submitted and enforced unless a revised Preliminary Drainage Plan is required by the City due to lot reconfiguration or other conditions created by the new development.
3. Submittal.
(i) A copy of the Preliminary Drainage Plan shall be submitted in a format specified by the City with the submittal of a Preliminary Plat or Replat for review and acceptance.
(ii) The Preliminary Drainage Plan shall be labeled as "Preliminary."
(iii) The Preliminary Drainage Plan shall be sealed by and dated by the engineer.
